April 2008 arXiv papers — page 33

S. Y. Zhou, D. A. Siegel, A. V. Fedorov, F. El Gabaly

We studied the effect of quantum confinement on the size of the band gap in single layer epitaxial graphene. Samples with different graphene terrace sizes are studied by using low energy electron microscopy (LEEM) and angle-resolved photoemission spectroscopy (ARPES). The direct correlation between the terrace size extracted from LEEM and the gap size extrac

V. R. Misko, B. Xu, F. M. Peeters

Recent experiments [I.V. Grigorieva et al., Phys. Rev. Lett. 96, 077005 (2006)] on visualization of vortices using the Bitter decoration technique revealed vortex shells in mesoscopic superconducting Nb disks containing up to L=40 vortices. Some of the found configurations did not agree with those predicted theoretically. We show here that this discrepancy c

M. Berberan-Santos, E. N. Bodunov, B. Valeur

The first use of the stretched exponential function to describe the time evolution of a non-equilibrium quantity is usually credited to Rudolph Kohlrausch (1809-1858), who in 1854 applied it to the discharge of a capacitor. Attention is drawn to a set of pioneering works on the Kohlrausch function, one of which published 101 years ago, and that are not menti

M. A. Guerrero, L. F. Miranda, A. Riera, P. F. Velazquez

With its remarkable double-S shape, IC 4634 is an archetype of point-symmetric planetary nebulae (PN). In this paper, we present a detailed study of this PN using archival HST WFPC2 and ground-based narrow-band images to investigate its morphology, and long-slit spectroscopic observations to determine its kinematics and to derive its physical conditions and

K. Raj Kumar, Giuseppe Caire

We present constructions of Space-Time (ST) codes based on lattice coset coding. First, we focus on ST code constructions for the short block-length case, i.e., when the block-length is equal to or slightly larger than the number of transmit antennas. We present constructions based on dense lattice packings and nested lattice (Voronoi) shaping. Our codes ach

H. Khiabanian, I. P. Dell'Antonio

Motivated by the limitations encountered with the commonly used direct reconstruction techniques of producing mass maps, we have developed a multi-resolution maximum-likelihood reconstruction method for producing two dimensional mass maps using weak gravitational lensing data. To utilize all the shear information, we employ an iterative inverse method with a

I. Paul, C. Pepin, M. R. Norman

We study the Kondo-Heisenberg model using a fermionic representation for the localized spins. The mean-field phase diagram exhibits a zero temperature quantum critical point separating a spin liquid phase where the f-conduction hybridization vanishes, and a Kondo phase where it does not. Two solutions can be stabilized in the Kondo phase, namely a uniform hy

Hiroko Shinnaga, Thomas G. Phillips, Ray S. Furuya, Riccardo Cesaroni

We used the CSO 10.4 meter telescope to image the 350 micron and 450 micron continuum and CO J=6-5 line emission of the IRAS 20126+4104 clump. The continuum and line observations show that the clump is isolated over a 4 pc region and has a radius of ~ 0.5 pc. Our analysis shows that the clump has a radial density profile propto r ^{-1.2} for r <~ 0.1 pc and

G. Seregin, V. Sverak

Local regularity of axially symmetric solutions to the Navier-Stokes equations is studied. It is shown that under certain natural assumptions there are no singularities of Type I.

Seth Redfield, Ross E. Falcon

We present a comprehensive survey of CII* absorption detections toward stars within 100 pc in order to measure the distribution of electron densities present in the local interstellar medium (LISM). Using high spectral resolution observations of nearby stars obtained by GHRS and STIS onboard the Hubble Space Telescope, we identify 13 sight lines with 23 indi

V. R. Misko, S. Savel&#39;ev, A. L. Rakhmanov, Franco Nori

We study theoretically the effects of heating on the magnetic flux moving in superconductors with a periodic array of pinning sites (PAPS). The voltage-current characteristic (VI-curve) of superconductors with a PAPS includes a region with negative differential resistivity (NDR) of S-type (i.e., S-shaped VI-curve), while the heating of the superconductor by

Raghunath Sahoo

Transverse energy ($E_T$) has been measured with both of it&#39;s components, namely hadronic ($E_T^{had}$) and electromagnetic ($E_T^{em}$) at mid-rapidity, for 62.4 GeV Au+Au collisions by the STAR experiment. In the common phase space of TPC and BEMC ($0 < η< 1$ and full $ϕ$), we have obtained $E_T^{had}$ from the TPC reconstructed tracks and $E_T^{em}$ f

Stephon Alexander, Nicolas Yunes

We study the tetrad formulation of Chern-Simons (CS) modified gravity, which adds a Pontryagin term to the Einstein-Hilbert action with a spacetime-dependent coupling field. We first verify that CS modified gravity leads to a theory with torsion, where this tensor is given by an antisymmetric product of the Riemann tensor and derivatives of the CS coupling.

Lorenzo J. Diaz, Anton Gorodetski

We prove that for a generic $C^1$-diffeomorphism existence of a homoclinic class with periodic saddles of different indices (dimension of the unstable bundle) implies existence an invariant ergodic non-hyperbolic (one of the Lyapunov exponents is equal to zero) measure of $f$.

Juan José Downes, César Briceño, Jesús Hernández, Nuria Calvet

We report the initial results of a large-scale optical-near infrared survey to extend the known young population of the entire Orion star-forming region down to the substellar domain. Using deep optical I-band photometry and data from the 2MASS survey, we selected candidates across ~14.8 deg^2 in the ~8 Myr old Ori OB1a subassociation and over ~6.7 deg^2 in

L. R. Bedin, M. Salaris, G. Piotto, S. Cassisi

In this paper we demonstrate that the puzzling bright peak in the luminosity function of the white dwarf (WD) cooling sequence of NGC6791 can be naturally accounted for if ~34% of the observed WDs are WD+WD binary systems.

Avery E. Broderick, Ramesh Narayan, Eric Keto, Charles J. Lada

In a previous paper we demonstrated that non-radial hydrodynamic oscillations of a thermally-supported (Bonnor-Ebert) sphere embedded in a low-density, high-temperature medium persist for many periods. The predicted column density variations and molecular spectral line profiles are similar to those observed in the Bok globule B68 suggesting that the motions

Domingo Gomez-Perez, Jaime Gutierrez, Alvar Ibeas, David Sevilla

Let p be a prime and a, c be integers such that a<>0 mod p. The quadratic generator is a sequence (u_n) of pseudorandom numbers defined by u_{n+1}=a*(u_n)^2+c mod p. In this article we probe that if we know sufficiently many of the most significant bits of two consecutive values u_n, u_{n+1}, then we can compute the seed u_0 except for a small number of exce

Ryan T. Glasser, Hugo Cable, Jonathan P. Dowling, Francesco De Martini

The study of optical parametric amplifiers (OPAs) has been successful in describing and creating nonclassical light for use in fields such as quantum metrology and quantum lithography [Agarwal, et al., J. Opt. Soc. Am. B, 24, 2 (2007)]. In this paper we present the theory of an OPA scheme utilizing an entangled state input. The scheme involves two identical

Néstor Aguilera, Pedro Morin

Many problems of theoretical and practical interest involve finding a convex or concave function. For instance, optimization problems such as finding the projection on the convex functions in $H^k(Ω)$, or some problems in economics. In the continuous setting and assuming smoothness, the convexity constraints may be given locally by asking the Hessian matrix

Guoqing Fan, J. R. Manson

When gas atoms or molecules collide with clean and ordered surfaces, under many circumstances the energy-resolved scattering spectra exhibit two clearly distinct features due to direct scattering and to trapping in the physisorption well with subsequent desorption. James Clerk Maxwell is credited with being the first to describe this situation by invoking th

I. Boztosun, D. Bonatsos, I. Inci

Analytical solutions of the Bohr Hamiltonian are obtained in the $γ$-unstable case, as well as in an exactly separable rotational case with $γ\approx 0$, called the exactly separable Morse (ES-M) solution. Closed expressions for the energy eigenvalues are obtained through the Asymptotic Iteration Method (AIM), the effectiveness of which is demonstrated by so

Troy A. Porter, Igor V. Moskalenko, Andrew W. Strong, Elena Orlando

A recent re-determination of the non-thermal component of the hard X-ray to soft gamma-ray emission from the Galactic ridge, using the SPI instrument on the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) Observatory, is shown to be well reproduced as inverse-Compton emission from the interstellar medium. Both cosmic-ray primary electrons and seco

Simone Giombi, Alexander Maloney, Xi Yin

We consider the one-loop partition function of free quantum field theory in locally Anti-de Sitter space-times. In three dimensions, the one loop determinants for scalar, gauge and graviton excitations are computed explicitly using heat kernel techniques. We obtain precisely the result anticipated by Brown and Henneaux: the partition function includes a sum

T. P. Waterhouse, J. P. Zibin

How much can we know about our Universe? All of our observations are restricted to a finite volume, and therefore our estimates of presumably global cosmological parameters are necessarily based on incomplete information. Even assuming that the Standard Model of cosmology is correct, this means that some cosmological questions may be unanswerable. For exampl

J. H. Groh, A. S. Oliveira, J. E. Steiner

The enigmatic object HD 45166 is a qWR star in a binary system with an orbital period of 1.596 day, and presents a rich emission-line spectrum in addition to absorption lines from the companion star (B7 V). As the system inclination is very small (i=0.77 +- 0.09 deg), HD 45166 is an ideal laboratory for wind-structure studies. The goal of the present paper i

P. Avogadro, F. Barranco, R. A. Broglia, E. Vigezzi

The structure of a vortex in the inner crust of neutron stars is calculated within the framework of quantum mean field theory taking into account the interaction with the nuclei composing the Coulomb lattice. Making use of the results obtained with different nuclear interactions, the pinning energy, relevant in the study of glitches, is worked out. Quantal s

Cristina Draper, Cándido Martín, Antonio Viruel

We describe all the fine group gradings, up to equivalence, on the Lie algebra $\mathfrak d_4$. This problem is equivalent to finding the maximal abelian diagonalizable subgroups of the automorphism group of $\mathfrak d_4$. We prove that there are fourteen by using two different viewpoints. The first approach is computational: we get a full description of t

Christophe Labreuche, Michel Grabisch

This paper addresses the question of which models fit with information concerning the preferences of the decision maker over each attribute, and his preferences about aggregation of criteria (interacting criteria). We show that the conditions induced by these information plus some intuitive conditions lead to a unique possible aggregation operator: the Choqu

Dmitry B. Rokhlin

For a $d$-dimensional stochastic process $(S_n)_{n=0}^N$ we obtain criteria for the existence of an equivalent martingale measure, whose density $z$, up to a normalizing constant, is bounded from below by a given random variable $f$. We consider the case of one-period model (N=1) under the assumptions $S\in L^p$; $f,z\in L^q$, $1/p+1/q=1$, where $p\in [1,\in

Michel Grabisch

We propose an extension of the Sugeno integral for negative numbers, in the spirit of the symmetric extension of Choquet integral, also called \Sipos\ integral. Our framework is purely ordinal, since the Sugeno integral has its interest when the underlying structure is ordinal. We begin by defining negative numbers on a linearly ordered set, and we endow thi

Dieter Denneberg, Michel Grabisch

We develop a purely ordinal model for aggregation functionals for lattice valued functions, comprising as special cases quantiles, the Ky Fan metric and the Sugeno integral. For modeling findings of psychological experiments like the reflection effect in decision behaviour under risk or uncertainty, we introduce reflection lattices. These are complete linear

Joerg M. Colberg, Tiziana Di Matteo

We make use of the first high--resolution hydrodynamic simulations of structure formation which self-consistently follows the build up of supermassive black holes introduced in Di Matteo et al. (2007) to investigate the relation between black holes (BH), host halo and large--scale environment. There are well--defined relations between halo and black hole mas

Garnet Kin-Lic Chan

We introduce a Lagrangian formulation of the Density Matrix Renormalization Group (DMRG). We present Lagrangians which when minimised yield the optimal DMRG wavefunction in a variational sense, both within the general matrix product ansatz, as well as within the canonical form of the matrix product that is constructed within the DMRG sweep algorithm. Some of

E. Loubeau, Y. -L. Ou

Inspired by the all-important conformal invariance of harmonic maps on two-dimensional domains, this article studies the relationship between biharmonicity and conformality. We first give a characterization of biharmonic morphisms, analogues of harmonic morphisms investigated by Fuglede and Ishihara, which, in particular, explicits the conditions required fo

M. S. Svanidze, Yu. G. Verbetsky

The properties of measuring systems of the Extensive Air Showers arrival directions (EAS goniometers), consisting of the set of spatially separated detectors registering the moments of EAS frontal passage, are considered. The advantage of volumetric goniometers in comparison with the commonly used flat ones is shown. The proper points selection method for de

Damir Becirevic, Svjetlana Fajfer, Jernej F. Kamenik

We determine the chiral corrections to the matrix elements of the Delta B=0 four-quark operators which are relevant to the studies of the ratios of lifetimes of heavy-light mesons as well as to the power corrections to the inclusive semileptonic heavy-to-light decays. The chiral logarithmic corrections computed here can be combined with the forthcoming estim

D. N. Voskresensky

Exact and approximate expressions for thermodynamic characteristics of heated matter, which consists of particles with finite mass-widths, are constructed. They are expressed in terms of Fermi/Bose distributions and spectral functions, rather than in terms of more complicated combinations between real and imaginary parts of the self-energies of different par

Giuseppe Durisi, Ulrich G. Schuster, Helmut Bölcskei, Shlomo Shamai

We derive bounds on the noncoherent capacity of wide-sense stationary uncorrelated scattering (WSSUS) channels that are selective both in time and frequency, and are underspread, i.e., the product of the channel&#39;s delay spread and Doppler spread is small. For input signals that are peak constrained in time and frequency, we obtain upper and lower bounds

LIGO Scientific Collaboration, B. Abbott

A search for periodic gravitational waves, from sources such as isolated rapidly-spinning neutron stars, was carried out using 510 hours of data from the fourth LIGO science run (S4). The search was for quasi-monochromatic waves in the frequency range from 50 Hz to 1500 Hz, with a linear frequency drift f-dot (measured at the solar system barycenter) in the

F. Hautmann, H. Jung

Experimental measurements of angular correlations in three-jet final states have recently been performed in DIS. Next-to-leading-order QCD results for these observables are affected by large theoretical uncertainties in the kinematic region of the data. We discuss the effects of multiple QCD radiation at higher order using parton-shower methods based on tran

Dmitry Anchishkin, Stanislav Yezhov

The partition function of nonequilibrium distribution which we recently obtained [arXiv:0802.0259] in the framework of the maximum isotropization model (MIM) is exploited to extract physical information from experimental data on the proton rapidity and transverse mass distributions. We propose to partition all interacting nucleons into ensembles in accordanc

Ginestra Bianconi

We derive the spectral properties of adjacency matrix of complex networks and of their Laplacian by the replica method combined with a dynamical population algorithm. By assuming the order parameter to be a product of Gaussian distributions, the present theory provides a solution for the non linear integral equations for the spectra density in random matrix

Gabriella De Lucia, Bianca M. Poggianti

We present recent results on the evolution of the colour-magnitude relation and of the star formation activity in galaxy clusters since z~0.8. Results are based on the ESO Distant Cluster Survey (EDisCS) - an ESO large programme aimed at the study of cluster structure and cluster galaxy evolution over a significant fraction of cosmic time - and are discussed

Ying Xu, Hosho Katsura, Takaaki Hirano, Vladimir E. Korepin

We study the inhomogeneous generalization of a 1-dimensional AKLT spin chain model. Spins at each lattice site could be different. Under certain conditions, the ground state of this AKLT model is unique and is described by the Valence-Bond-Solid (VBS) state. We calculate the density matrix of a contiguous block of bulk spins in this ground state. The density

Carl Bracken

We define a pseudo quasi-3 design as a symmetric design with the property that the derived and residual designs with respect to at least one block are quasi-symmetric. Quasi-symmetric designs can be used to construct optimal self complementary codes. In this article we give a construction of an infinite family of pseudo quasi-3 designs whose residual designs

I. Antoniadis, J. P. Derendinger, T. Maillard

Nonlinear supersymmetry is used to compute the general form of the effective D-brane action in type I string theory compactified to four dimensions in the presence of internal magnetic fields. In particular, the scalar potential receives three contributions: (1) a nonlinear part of the D-auxiliary component, associated to the Dirac-Born-Infeld action; (2) a

Larry McLerran

These two lectures concern the Color Glass Condensate and the Glasma. These are forms of matter which might be studied in high energy hadronic collisions. The Color Glass Condensate is high energy density gluonic matter. It constitutes the part of a hadron wavefunction important for high energy processes. The Glasma is matter produced from the collision of t

Mahdi Momeni, Wolf-Christian Müller

Probability density functions (PDFs) of scale-dependent energy fluctuations, $P[δE(\ell)]$, are studied in high-resolution direct numerical simulations of Navier-Stokes and incompressible magnetohydrodynamic (MHD) turbulence. MHD flows with and without a strong mean magnetic field are considered. For all three systems it is found that the PDFs of inertial ra

Bo Li, Xing Li

We present multicomponent solar wind models self-consistently incorporating the contribution from dissipationless, monochromatic, finite-wavelength (non-WKB), hydromagnetic, toroidal Alfvén waves, which are coupled to the flow only through the ponderomotive forces. We find that the non-WKB effects are significant, for the fast and slow solar wind solutions a

Niels Groenbaek

Let A be a Banach algebra and let X be a Banach A -bimodule. In studying the bounded Hochschild cohomology groups H^1(A,X) it is often useful to extend a given derivation D: A-> X to a Banach algebra B containing A as an ideal, thereby exploiting (or establishing) hereditary properties. This is usually done using (bounded/unbounded) approximate identities to

Richard Atkins

We consider when a smooth vector bundle endowed with a connection possesses non-trivial, local parallel sections. This is accomplished by means of a derived flag of subsets of the bundle. The procedure is algebraic and rests upon the Frobenius Theorem.

Cong Ren, Zhao-Sheng Wang, Huan Yang, Xiyu Zhu

We present the first experimental results of the lower critical field $H_{c1}$ of the newly discovered F-doped superconductor LaO$_{0.9}$F$_{0.1}$FeAs (F-LaOFeAs) by global and local magnetization measurements. It is found that $H_{c1}$ showed an clear linear-$T$ dependence down to a temperature of 2 K, indicative of an unconventional pairing symmetry with a

Ariel Blanco, Niels Groenbaek

We give a necessary and sufficient condition for amenability of the Banach algebra of approximable operators on a Banach space. We further investigate the relationship between amenability of this algebra and factorization of operators, strengthening known results and developing new techniques to determine whether or not a given Banach space carries an amenab

Sudipto Guha, Kamesh Munagala, Saswati Sarkar

A wireless system with multiple channels is considered, where each channel has several transmission states. A user learns about the instantaneous state of an available channel by transmitting a control packet in it. Since probing all channels consumes significant energy and time, a user needs to determine what and how much information it needs to acquire abo

Lucie Baudouin, Denis Arzelier, Christophe Prieur, Fabien Guignard

We apply robust control technics to an adaptive optics system including a dynamic model of the deformable mirror. The dynamic model of the mirror is a modification of the usual plate equation. We propose also a state-space approach to model the turbulent phase. A continuous time control of our model is suggested taking into account the frequential behavior o

Cheng-Wei Chiang, Eibun Senaha

We study the Higgs sector of the secluded $U(1)&#39;$-extended MSSM (sMSSM) focusing on CP violation. Using the one-loop effective potential that includes contributions from quarks and squarks in the third generation, we search for the allowed region under theoretical and experimental constraints. It is found that the possible region for the electroweak vacu

Leonid Galtchouk, Serguey Pergamenshchikov

An adaptive nonparametric estimation procedure is constructed for the estimation problem of heteroscedastic regression when the noise variance depends on the unknown regression. A non-asymptotic upper bound for a quadratic risk (an oracle inequality) is constructed.

Leonid Galtchouk, Serguey Pergamenshchikov

Asymptotic efficiency is proved for the constructed in part 1 procedure, i.e. Pinsker&#39;s constant is found in the asymptotic lower bound for the minimax quadratic risk. It is shown that the asymptotic minimax quadratic risk of the constructed procedure coincides with this constant.

Lucie Baudouin, Alberto Mercado

This paper concerns the inverse problem of retrieving a stationary potential for the Schrödinger evolution equation in a bounded domain of RN with Dirichlet data and discontinuous principal coefficient a(x) from a single time-dependent Neumann boundary measurement. We consider that the discontinuity of a is located on a simple closed hyper-surface called the

P. N. Timonin

Phenomenological thermodynamic theory describing the properties of metastable states in disordered ferromagnets and ferroelectrics with frustrative random interactions is developed and its ability to describe various nonergodic phenomena in real crystals is demonstrated.

Matthias Christandl

Horn&#39;s problem asks for the conditions on sets of integers mu, nu and lambda that ensure the existence of Hermitian operators A, B and A+B with spectra mu, nu and lambda, respectively. It has been shown that this problem is equivalent to deciding whether the irreducible representation of GL(d) with highest weight lambda is contained in the tensor product

Lucie Baudouin, Julien Salomon

Often considered in numerical simulations related to the control of quantum systems, the so-called monotonic schemes have not been so far much studied from the functional analysis point of view. Yet, these procedures provide an efficient constructive method for solving a certain class of optimal control problems. This paper aims both at extending the results

Luis Miguel Rodrigues

Bidimensional incompressible viscous flows with well-localised vorticity are well-known to develop vortex structures. The purpose of the present paper is to recover the asymptotic profiles describing these phenomena for homogeneous finite-energy flows as asymptotic profiles for near-equilibrium isentropic compressible flows. This task is performed by extendi

Lucie Baudouin, Alberto Mercado, Axel Osses

We consider a transmission wave equation in two embedded domains in $R^2$, where the speed is $a1 > 0$ in the inner domain and $a2 > 0$ in the outer domain. We prove a global Carleman inequality for this problem under the hypothesis that the inner domain is strictly convex and $a1 > a2$ . As a consequence of this inequality, uniqueness and Lip- schitz stabil

Roger Lewandowski, Yves Preaux

We consider a deconvolution model for 3D periodic flows. We show the existence of a global attractor for the model.

Jaime Gutierrez, David Sevilla

In this paper we present an algorithm for computing all algebraic intermediate subfields in a separably generated unirational field extension (which in particular includes the zero characteristic case). One of the main tools is Groebner bases theory. Our algorithm also requires computing computing primitive elements and factoring over algebraic extensions. M

M. Bondi, P. Ciliegi, E. Schinnerer, V. Smolcic

The VLA-COSMOS Large Project has imaged the 2 sq.deg. COSMOS field with a resolution of 1.5 arcsec and a sensitivity of about 11 microJy (1 sigma) yielding to a catalog of about 3600 radio sources. In this paper we present a further analysis of the VLA-COSMOS Large Project catalog of radio sources aimed to: 1) quantify and correct for the effect of bandwidth

Yi Li, Eric Perlman, Minping Wan, Yunke Yang

A public database system archiving a direct numerical simulation (DNS) data set of isotropic, forced turbulence is described in this paper. The data set consists of the DNS output on $1024^3$ spatial points and 1024 time-samples spanning about one large-scale turn-over timescale. This complete $1024^4$ space-time history of turbulence is accessible to users

S. Savo, E. Di Gennaro, C. Miletto, A. Andreone

At the exit surface of a photonic crystal, the intensity of the diffracted wave can be periodically modulated, showing a maximum in the &#34;positive&#34; (forward diffracted) or in the &#34;negative&#34; (diffracted) direction, depending on the slab thickness. This thickness dependence is a direct result of the so-called Pendellosung phenomenon, consisting

Amalendu Krishna

We prove an Artin-Rees type theorem for algebraic cycles and give an application to zero cycles.

G. Royer, H. F. Zhang

New recent experimental $α$ decay half-lives have been compared with the results obtained from previously proposed formulas depending only on the mass and charge numbers of the $α$ emitter and the Q$α$ value. For the heaviest nuclei they are also compared with calculations using the Density-Dependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-So

Shrinivas Kudekar, Ruediger Urbanke

We consider lossy compression of a binary symmetric source by means of a low-density generator-matrix code. We derive two lower bounds on the rate distortion function which are valid for any low-density generator-matrix code with a given node degree distribution L(x) on the set of generators and for any encoding algorithm. These bounds show that, due to the

Carlos P. Herrero

The antiferromagnetic Ising model in small-world networks generated from two-dimensional regular lattices has been studied. The disorder introduced by long-range connections causes frustration, which gives rise to a spin-glass phase at low temperature. Monte Carlo simulations have been carried out to study the paramagnetic to spin-glass transition, as a func

Néstor E. Aguilera, Pedro Morin

Many problems of theoretical and practical interest involve finding an optimum over a family of convex functions. For instance, finding the projection on the convex functions in $H^k(Ω)$, and optimizing functionals arising from some problems in economics. In the continuous setting and assuming smoothness, the convexity constraints may be given locally by ask

F. M. D. Pellegrino, G. G. N. Angilella, N. H. March, R. Pucci

Using a proposed generalization of the pair distribution function for a gas of non-interacting particles obeying fractional exclusion statistics in arbitrary dimensionality, we derive the statistical correlations in the asymptotic limit of vanishing or low temperature. While Friedel-like oscillations are present in nearly all non-bosonic cases at T=0, they a

Rodrigo Labouriau, Poul Sørensen, Helle R. Juul-Madsen

We consider the problem of detecting and estimating the strength of association between a trait of interest and alleles or haplotypes in a small genomic region (e.g. a gene or a gene complex), when no direct information on that region is available but the values of neighbouring DNA-markers are at hand. We argue that the effects of the non-observable haplotyp

Xavier Waintal, Genevieve Fleury, Kyryl Kazymyrenko, Manuel Houzet

We discuss the sign of the persistent current of N electrons in one dimensional rings. Using a topology argument, we establish lower bounds for the free energy in the presence of arbitrary electron-electron interactions and external potentials. Those bounds are the counterparts of upper bounds derived by Leggett. Rings with odd (even) numbers of polarized el

Jaime Gutierrez, David Sevilla

The classical Ritt&#39;s Theorems state several properties of univariate polynomial decomposition. In this paper we present new counterexamples to Ritt&#39;s first theorem, which states the equality of length of decomposition chains of a polynomial, in the case of rational functions. Namely, we provide an explicit example of a rational function with coeffici

Ralf Schützhold, William G. Unruh

We present an analytic derivation of Hawking radiation for an arbitrary (spatial) dispersion relation $ω(k)$ as a model for ultra-high energy deviations from general covariance. It turns out that the Hawking temperature is proportional to the product of the group $dω/dk$ and phase $ω/k$ velocities evaluated at the frequency $ω$ of the outgoing radiation far

Giorgio Cortiana

Top quark pair production cross section has been measured at the Tevatron by CDF and $DØ$ collaborations using different channels and methods, in order to test standard model predictions, and to search for new physics hints affecting the $t\bar t$ production mechanism or decay. Measurements are carried out with an integrated luminosity of 1.0 to 2.0 fb$^{-1}

M. Ericson, G. Chanfray

Relativistic theories of nuclear matter are discussed in a new pespective. First the chiral character of the scalar nuclear field is introduced in the framework of the linear sigma model. With the assumption that the nucleon mass originates in part from the coupling to the quark condensate it is possible to relate the optical potential for the propagation of

Frederic Campana, Keiji Oguiso, Thomas Peternell

We study the algebraic dimension a(X) of a compact hyperkaehler manfold of dimension 2n. We show that a(X) is at most n unless X is projective. If a compact Kaehler manifold with algebraic dimension 0 and Kodaira dimension 0 has a minimal model, then only the values 0,n and 2n are possible. In case of middle dimension, the algebraic reduction is holomorphic

Prabuddha Sanyal, Sabyasachi Tarat, Pinaki Majumdar

We formulate an effective model for B-B&#39; site ordering in double perovskite materials A_2BB&#39;O_6. Even within the simple framework of lattice-gas type models, we are able to address several experimentally observed issues including nonmonotonic dependence of the degree of order on annealing temperature, and the rapid decrease of order upon overdoping w

Teruhisa Tsuda

We present a unified description of birational representation of Weyl groups associated with T-shaped Dynkin diagrams, by using a particular configuration of points in the projective plane. A geometric formulation of tau-functions is given in terms of defining polynomials of certain curves. If the Dynkin diagram is of affine type ($E_6^{(1)}$, $E_7^{(1)}$ or

Jaime Gutierrez, David Sevilla

One of the main contributions which Volker Weispfenning made to mathematics is related to Groebner bases theory. In this paper we present an algorithm for computing all algebraic intermediate subfields in a separably generated unirational field extension (which in particular includes the zero characteristic case). One of the main tools is Groebner bases theo

S. V. Maleyev

The magneto-elastic interaction in cubic helimagnets with B20 symmetry is considered. It is shown that this interaction is responsible for negative contribution to the square of the spin-wave gap $Δ$ which is alone has to disrupt assumed helical structure. It is suggested that competition between positive part of $Δ^2_I$ which stems from magnon-magnon intera

Petr Seba

During the attempt to park a car in the city the drivers have to share limited resources (the available roadside). We show that this fact leads to a predictable distribution of the distances between the cars that depends on the length of the street segment used for the collective parking. We demonstrate in addition that the individual parking maneuver is gui

G. Ghirlanda, L. Nava, G. Ghisellini, C. Firmani

We study the distribution of long Gamma Ray Bursts in the Ep-Eiso and in the Ep,obs-Fluence planes through an updated sample of 76 bursts, with measured redshift and spectral parameters, detected up to September 2007. We confirm the existence of a strong rest frame correlation Ep ~ Eiso^0.54+-0.01. Contrary to previous studies, no sign of evolution with reds

B. H. Lavenda

Special relativity corresponds to hyperbolic geometry at constant velocity while the so-called general relativity corresponds to hyperbolic geometry of uniformly accelerated systems. Generalized expressions for angular momentum, centrifugal and Coriolis forces are found in hyperbolic space, which reduce to the usual expressions of Euclidean space when the ab

A. Chatterjee, A. Sarkar, P. Barat, P. Mukherjee

The Portevin-Le Chatelier(PLC) effect has been investigated by deforming Al-2.5%Mg alloy in the strain rate regime where simultaneously two types (type B and type A) of serrations appear in the stress strain curve. Our analysis reveal that in this strain rate regime the entire PLC dynamics for a particular strain rate experiment is governed by a single band

Sudhir R. Ghorpade, Arunkumar R. Patil, Harish K. Pillai

We discuss the problem of determining the complete weight hierarchy of linear error correcting codes associated to Grassmann varieties and, more generally, to Schubert varieties in Grassmannians. The problem is partially solved in the case of Grassmann codes, and one of the solutions uses the combinatorial notion of a closed family. We propose a generalizati

M. Sigalov, E. O. Kamenetskii, R. Shavit

In confined magnetically ordered structures one can observe vortices of magnetization and electromagnetic power flow vortices. There are topologically distinct and robust states. In this paper we show that in a normally magnetized quasi-2D ferrite disk there exist eigen power-flow-density vortices of magnetic-dipolar-mode oscillations. Because of such circul

Caterina Stoppato

This paper studies the singularities of Cullen-regular functions of one quaternionic variable. The quaternionic Laurent series prove to be Cullen-regular. The singularities of Cullen-regular functions are thus classified as removable, essential or poles. The quaternionic analogues of meromorphic complex functions, called semiregular functions, turn out to be

B. S. González, J. Hernández-Rojas, J. Bretón, J. M. Gomez Llorente

The water-graphite interaction potential proposed recently (González et al.\emph{J. Phys. Chem. C} \textbf{2007}, \emph{111}, 14862), the three TIP$N$P ($N=3,\:4,\:5$) water-water interaction models, and basin-hopping global optimization are used to find the likely candidates for the global potential energy minima of (H$_{2}$O)$_{n}$ clusters with $n\leq21$

J. Roé, J. Ross

Let X be a projective variety of dimension n and L be a nef divisor on X. Denote by e_d(r;X,L) the d-dimensional Seshadri constant of r very general points in X. We prove that e_d(rs;X,L) >= e_d(r;X,L)e_d(s;P^n,O_{P^n}(1)).

Francis Brown

We introduce a new method for computing massless Feynman integrals analytically in parametric form. An analysis of the method yields a criterion for a primitive Feynman graph $G$ to evaluate to multiple zeta values. The criterion depends only on the topology of $G$, and can be checked algorithmically. As a corollary, we reprove the result, due to Bierenbaum

S. Vigni

If E is a non-isotrivial elliptic curve over a global function field F of odd characteristic we show that certain Mordell-Weil groups of E have 1-dimensional eigenspace relative to a fixed complex ring class character provided that the projection onto this eigenspace of a suitable Drinfeld-Heegner point is nonzero. This represents the analogue in the functio

Svante Janson

We study the random graph obtained by random deletion of vertices or edges from a random graph with given vertex degrees. A simple trick of exploding vertices instead of deleting them, enables us to derive results from known results for random graphs with given vertex degrees. This is used to study existence of giant component and existence of k-core. As a v

A. Kanaev, L. Museur, F. Edery, T. Laarmann

The formation of the electronic structure of small Kr_m clusters (m<150) embedded inside Ne_N clusters (1200<N<7500) has been investigated with the help of fluorescence excitation spectroscopy using synchrotron radiation. Electronically excited states, assigned to excitons at the Ne/Kr interface, 1i and 1&#39;i were observed. The absorption bands, which are