January 2009 arXiv papers — page 29

Chad Groft

Let X be a finite CW complex or compact Lipschitz neighborhood retract with universal cover Z; let M be a compact orientable manifold of dimension at least 2 and nonempty boundary. We establish the existence of an isoperimetric profile for functions from M to Z, in the metric and cellular senses, and show that they are equivalent up to scaling factors when X

Jeremy Bailin, William E. Harris

We develop a model for stochastic pre-enrichment and self-enrichment in globular clusters (GCs) during their formation process. GCs beginning their formation have an initial metallicity determined by the pre-enrichment of their surrounding protocloud, but can also undergo internal self-enrichment during formation. Stochastic variations in metallicity arise b

Miloslav Havlíček, Edita Pelantová, Jiří Tolar

The paper extends existing Lie algebra representation theory related to Lie algebra gradings. The notion of a representation compatible with a given grading is defined and applied to finite-dimensional representations of $sl(n,\mathbb{C})$ in relation with its $\mathbb{Z}_2$-gradings. For representation theory of $sl(n,\mathbb{C})$ the Gel'fand-Tseitlin

J. A. Lorenzo Fernandez, M. R. Osorio, J. A. Veira, F. Vidal

High-temperature superconducting microbridges implemented with YBa(2)Cu(3)O(7-delta) thin-films are shown to be possible fault current limiters for microelectronic devices with some elements working at temperatures below the superconducting critical temperature and, simultaneously, under very low power conditions (below 1W). This is the case in the important

A. V. Roiter, S. A. Kryglyak, L. A. Nazarova

As it is known, finitely presented quivers correspond to Dynkin graphs (Gabriel, 1972) and tame quivers -- to extended Dynkin graphs (Donovan and Freislich, Nazarova, 1973). In the article "Locally scalar reresentations of graphs in the category of Hilbers spaces" (Func. Anal. and Appl., 2005) authors showed the way to tranfer these results to Hilber

Giancarlo Jug

Puzzling observations of both thermal and dielectric responses in multi-silicate glasses at low temperatures $T$ to static magnetic fields $B$ have been reported in the last decade and call for an extension of the standard two-level systems tunneling model. An explanation is proposed, capable of capturing at the same time the $T$- and $B$-dependence of the s

R Matthews, A. A. Louis, J. M. Yeomans

We present a numerical study of the effect of knotting on the ejection of flexible and semiflexible polymers from a spherical, virus-like capsid. The polymer ejection rate is primarily controlled by the knot, which moves to the hole in the capsid and then acts as a ratchet. Polymers with more complex knots eject more slowly and, for large knots, the knot typ

Oren Kolman

Examples are given of non-elementary properties that are preserved under C-filtrations for various classes C of Abelian groups. The Baer-Specker group is never the union of a chain of proper subgroups with cotorsionfree quotients. Cotorsion-free groups form an abstract elementary class (AEC). The Kaplansky invariants of the Baer-Specker group are used to det

Yan Guo, Juhi Jang, Ning Jiang

Based on a recent $L^{2}{-}L^{\infty}$ framework, we establish the acoustic limit of the Boltzmann equation for general collision kernels. The scaling of the fluctuations with respect to Knudsen number is optimal. Our approach is based on a new analysis of the compressible Euler limit of the Boltzmann equation, as well as refined estimates of Euler and acous

Alessia Cattabriga, Michele Mulazzani, Andrei Vesnin

We deal with Matveev complexity of compact orientable 3-manifolds represented via Heegaard diagrams. This lead us to the definition of modified Heegaard complexity of Heegaard diagrams and of manifolds. We define a class of manifolds which are generalizations of Dunwoody manifolds, including cyclic branched coverings of two-bridge knots and links, torus knot

Ivana Agnolin, Jean-Noël Roux

Elastic properties and internal states of isotropic sphere packings are studied by numerical simulations. Several numerical protocols to assemble dense configurations are compared. One, which imitates experiments with lubricated contacts, produces well coordinated states, while another, mimicking the effect of vibrations, results, for the same density, in a

F. Bruckmann, F. Gruber, C. B. Lang, M. Limmer

We systematically compare filtering methods used to extract topological excitations from lattice gauge configurations. We show that there is a strong correlation of the topological charge densities obtained by APE and Stout smearing. Furthermore, a first quantitative analysis of quenched and dynamical configurations reveals a crucial difference of their topo

Elliot Leader, Alexander V. Sidorov, Dimiter B. Stamenov

The present status of the longitudinal polarized parton densities (PDFs) and the contribution of their first moments to the nucleon spin is discussed. Special attention is paid to the role of higher twist effects in determining the PDFs and to the polarized strange quark and gluon densities, which are still not well determined from the present data.

Jean-Paul Blaizot, Maciej A. Nowak

Many features of large N_c transition that occurs in the spectral density of Wilson loops as a function of loop area (observed recently in numerical simulations of Yang-Mills theory by Narayanan and Neuberger) can be captured by a simple Burgers equation used to model turbulence. Spectral shock waves that precede this asymptotic limit exhibit universal scali

M. N. Makhonin, J. Skiba-Szymanska, M. S. Skolnick, H. -Y. Liu

Sharp threshold-like transitions between two stable nuclear spin polarizations are observed in optically pumped individual InGaAs self-assembled quantum dots embedded in a Schottky diode when the bias applied to the diode is tuned. The abrupt transitions lead to the switching of the Overhauser field in the dot by up to 3 Tesla. The bias-dependent photolumine

A. Piscitelli, F. Corberi, G. Gonnella, A. Pelizzola

Fluctuation relations for the entropy production in non equilibrium stationary states of Ising models are investigated by Monte Carlo simulations. Systems in contact with heat baths at two different temperatures or subject to external driving will be studied. In the first case, by considering different kinetic rules and couplings with the baths, the behavior

A. E. Nikolaenko, E. A. Chekhovich, M. N. Makhonin, I. W. Drouzas

Nuclear spin polarization dynamics are measured in optically pumped individual GaAs/AlGaAs interface quantum dots by detecting the time-dependence of the Overhauser shift in photoluminescence (PL) spectra. Long nuclear polarization decay times of ~ 1 minute have been found indicating inefficient nuclear spin diffusion from the GaAs dot into the surrounding A

Markus Hunziker, Mark R. Sepanski, Ronald J. Stanke

We give a uniform realization of the minimal representation of a double cover of the conformal group SO(2,n+1)_0 in the kernel of the wave operator on flat Minkowski space as a positive energy representation H^+ for n even and odd. Using this realization, we obtain an explicit orthonormal basis for H^+ that is well behaved with respect to energy and angular

Ibrar Hussain, Asghar Qadir

Using Lie symmetry methods for differential equations we have investigated the symmetries of a Lagrangian for a plane symmetric static spacetime. Perturbing this Lagrangian we explore its approximate symmetries. It has a non-trivial first-order approximate symmetry.

M. Emprechtinger, M. C. Wiedner, R. Simon, G. Wieching

NGC 2024, a sites of massive star formation, have complex internal structures caused by cal heating by young stars, outflows, and stellar winds. These complex cloud structures lead to intricate emission line shapes. The goal of this paper is to show that the complex line shapes of 12 CO lines in NGC 2024 can be explained consistently with a model, whose temp

Gilles Zumbach

For a given time horizon DT, this article explores the relationship between the realized volatility (the volatility that will occur between t and t+DT), the implied volatility (corresponding to at-the-money option with expiry at t+DT), and several forecasts for the volatility build from multi-scales linear ARCH processes. The forecasts are derived from the p

Laura Magrini, Letizia Stanghellini, Eva Villaver

The Planetary Nebula (PN) population of M33 is studied via multi-fiber spectroscopy with Hectospec at the MMT. In this paper we present the spectra of 102 PNe, whereas plasma diagnostic and chemical abundances were performed on the 93 PNe where the necessary diagnostic lines were measured. About 20% of the PNe are compatible with being Type I; the rest of th

P. Bozek

A very early start up time of the hydrodynamic evolution is needed in order to reproduce observations from relativistic heavy-ion collisions experiments. At such early times the systems is still not locally equilibrated. Another source of deviations from local equilibrium is the viscosity of the fluid. We study these effects at very early times to obtain a d

Robert Morelos-Zaragoza

This paper deals with superposition coding for cooperative broadcasting in the case of two coordinated source nodes, as introduced in the seminal work of Bergmans and Cover in 1974. A scheme is introduced for two classes of destination (or relay) nodes: Close nodes and far nodes, as ranked by their spatial distances to the pair of transmitting nodes. Two lin

M. J. Coe, M. Schurch, V. A. McBride, R. H. D. Corbet

Optical and X-ray observations are presented here of a newly reported X-ray transient system in the Small Magellanic Cloud - SXP7.92. A detailed analysis of the X-ray data reveal a coherent period of 7.9s. A search through earlier X-ray observations of the SMC reveal a previously unknown earlier detection of this system. Follow-up X-ray observations identifi

D. Kotschick, S. Terzic

We provide examples of homogeneous spaces which are neither symmetric spaces nor real cohomology spheres, yet have the property that every invariant metric is geometrically formal. We also extend the known obstructions to geometric formality to some new classes of homogeneous spaces and of biquotients, and to certain sphere bundles.

J. E. Steiner, R. B. Menezes, T. V. Ricci, A. S. Oliveira

Astronomy has evolved almost exclusively by the use of spectroscopic and imaging techniques, operated separately. With the development of modern technologies it is possible to obtain datacubes in which one combines both techniques simultaneously, producing images with spectral resolution. To extract information from them can be quite complex, and hence the d

S. -J. Paardekooper, J. C. B. Papaloizou

We study the torque on low mass protoplanets on fixed circular orbits, embedded in a protoplanetary disc in the isothermal limit. For low mass protoplanets and large viscosity the corotation torque behaves as expected from linear theory. However, when the viscosity becomes small enough to enable horseshoe turns to occur, the linear corotation torque exists o

Nobuhiro Honda, Fuminori Nakata

In this paper we show that the space of nodal rational curves, which is so called a Severi variety (of rational curves), on any non-singular projective surface is always equipped with a natural Einstein-Weyl structure, if the space is 3-dimensional. This is a generalization of the Einstein-Weyl structure on the space of smooth rational curves on a complex su

S. -J. Paardekooper, J. C. B. Papaloizou

We study the coorbital flow for embedded, low mass planets. We provide a simple semi-analytic model for the corotation region, which is subsequently compared to high resolution numerical simulations. The model is used to derive an expression for the half-width of the horseshoe region, x_s, which in the limit of zero softening is given by x_s/r_p = 1.68(q/h)^

Alexander Laschka, Norbert Kaiser, Wolfram Weise

The heavy quark-antiquark potential in perturbative QCD is subject to ambiguities. We show how to derive a well-defined and stable short-distance potential that can be matched to results from lattice QCD simulations at intermediate distances. The static potential as well as the order 1/m potential are discussed.

Zuqiang Ma, Junliang Cai

As a natural generalization of chromatic number of a graph, the circular chromatic number of graphs (or the star chromatic number) was introduced by A.Vince in 1988. Let $M^t(G)$ denote the $t$th iterated Mycielski graph of $G$. It was conjectured by Chang, Huang and Zhu(Discrete mathematics,205(1999), 23-37) that for all $n \ge t+2, χ_c(M^t(K_n))=χ(M^t(K_n)

Beike Hiemstra, Paolo Soleri, Mariano Mendez, Tomaso Belloni

We analyzed simultaneous archival XMM-Newton and RXTE observations of the X-ray binary and black hole candidate Swift J1753.5-0127. In a previous analysis of the same data a soft thermal component was found in the X-ray spectrum, and the presence of an accretion disk extending close to the innermost stable circular orbit was proposed. This is in contrast wit

O Foda, M Wheeler, M Zuparic

We observe that the partition function of the six vertex model on a finite square lattice with domain wall boundary conditions is (a restriction of) a KP tau function and express it as an expectation value of charged free fermions (up to an overall normalization).

Manuel Morillo, José Gómez-Ordóñez, José M. Casado, Jesús Casado-Pascual

In this article, we investigate the stochastic resonance (SR) effect in a finite array of noisy bistable systems with nearest-neighbor coupling driven by a weak time-periodic driving force. The array is characterized by a collective variable. By means of numerical simulations, the signal-to-noise ratio (SNR) and the gain are estimated as functions of the noi

H. B. Nersisyan, A. K. Das

The results of a theoretical investigation on the stopping power of ions moving in a disordered two-dimensional degenerate electron gas are presented. The stopping power for an ion is calculated employing linear response theory using the dielectric function approach. The disorder, which leads to a damping of plasmons and quasiparticles in the electron gas, i

O. P. Zhelenkova, A. I. Kopylov

Radio sources of the RC catalog produced in 1980--1985 at RATAN-600 radio telescope based on a deep survey of a sky strip centered on the declination of the SS 433 source are optically identified in the region overlapping with FIRST and SDSS surveys (about 132 square degrees). The NVSS catalog was used as the reference catalog for refining the coordinates of

J. Anderson, H. Nordman, R. Singh, J. Weiland

In the present work the generation of zonal flows in collisionless trapped electron mode (TEM) turbulence is studied analytically. A reduced model for TEM turbulence is utilized based on an advanced fluid model for reactive drift waves. An analytical expression for the zonal flow growth rate is derived and compared with the linear TEM growth, and its scaling

M. N. Kiselev, K. Kikoin

The exactly solvable Keldysh model of disordered electron system in a random scattering field with extremely long correlation length is converted to the time-dependent model with extremely long relaxation. The dynamical problem is solved for the ensemble of two-level systems (TLS) with fluctuating well depths having the discrete Z_2 symmetry. It is shown als

M. I. Vysotsky

The final state interactions (FSI) model, in which soft rescattering of low mass intermediate states dominate, is suggested. It explains why the strong interaction phases are large in the $B_d\toππ$ channel and are considerably smaller in the $B_d\toρρ$ one.

M. J. Cantero, F. A. Grünbaum, L. Moral, L. Velazquez

We consider quantum random walks (QRW) on the integers, a subject that has been considered in the last few years in the framework of quantum computation. We show how the theory of CMV matrices gives a natural tool to study these processes and to give results that are analogous to those that Karlin and McGregor developed to study (classical) birth-and-death p

J C Knott, D C Pond, R A Lewis

Of the perovskites, ABX_<3>, a subset of special interest is the family in which the A site is occupied by a lanthanide ion, the B site by a rare earth and X is oxygen, as such materials often exhibit a large change in electrical resistance in a magnetic field, a phenomenon known as &#34;colossal&#34; magnetoresistance (MR). Two additional phenomena in this

Johan Anderson, Eun-jin Kim

A theory of the probability distribution function (PDF) tails of the blob density in plasma edge turbulence is provided. A simplified model of the fast convective radial transport is used. The theoretically predicted PDF tails corroborate earlier measurements of edge transport, further confirming the strongly non-Gaussian feature of edge transport. It is fou

F. Bernardini, G. L. Israel, S. Dall&#39;Osso, L. Stella

XTE J1810-197 is the first transient Anomalous X-ray Pulsar ever discovered. Its highly variable X-ray flux allowed us to study the timing and spectral emission properties of a magnetar candidate over a flux range of about two orders of magnitude. We analyzed nine XMM-Newton observations of XTE J1810-197 collected over a four years baseline (September 2003 -

Sutapa Sen

We present a phenomenological study of neutral gauge bosons and fermions in an extended Standard model with SU(3)C x SU(4)L x U(1)X gauge symmetry.The model includes gauge bosons and fermions without exotic charges and is distinguished by the symmetry-breaking patern SU(4)L->SU(2)L x SU(2)H x U(1)AH. This introduces an extended electroweak symmetry group SU(

Johan Anderson, Eun-jin Kim

The probability distribution function (PDF) tails of the zonal flow structure formation and the PDF tails of momentum flux by incorporating effect of a shear flow in ion-temperature-gradient (ITG) turbulence are computed in the present paper. The bipolar vortex soliton (modon) is assumed to be the coherent structure responsible for bursty and intermittent ev

T. B. S. Jensen, N. B. Christensen, M. Kenzelmann, H. M. Rønnow

Neutron diffraction is used to probe the (H,T) phase diagram of magneto-electric (ME) LiNiPO4 for magnetic fields along the c-axis. At zero field the Ni spins order in two antiferromagnetic phases. One has commensurate (C) structures and general ordering vectors (0,0,0), the other one is incommensurate (IC) with ordering vector (0,q,0). At low temperatures t

Yoshihiko Okamoto, Hiroyuki Yoshida, Zenji Hiroi

A polycrystalline sample of vesignieite BaCu3V2O8(OH)2 comprising a nearly ideal kagome lattice composed of Cu2+ ions carrying spin 1/2 has been synthesized and studied by magnetization and heat capacity measurements. Magnetic susceptibility shows a neither long range order, a spin glass transition nor a spin gap down to 2 K, in spite of a moderately strong

Johan Anderson, Eun-jin Kim

There has been overwhelming evidence that coherent structures play a critical role in determining the overall transport in a variety of systems. We compute the probability distribution function (PDF) tails of momentum flux and heat flux in ion-temperature-gradient turbulence, by taking into account the interaction among modons, which are assumed to be cohere

Stefan Haufe, Guido Nolte, Klaus-Robert Mueller, Nicole Kraemer

Our goal is to estimate causal interactions in multivariate time series. Using vector autoregressive (VAR) models, these can be defined based on non-vanishing coefficients belonging to respective time-lagged instances. As in most cases a parsimonious causality structure is assumed, a promising approach to causal discovery consists in fitting VAR models with

J. Bellazzini, N. Visciglia

Following the original approach introduced by T. Cazenave and P.L. Lions in \cite{CaLi} we prove the existence and the orbital stability of standing waves for the following class of NLS: \label{intr1} i\partial_t u+ Δu - V(x) u + Q(x) u|u|^{p-2}=0, \hbox{} (t,x) \in \R\times \R^n, \hbox{} 2<p<2+\frac 4n and \label{intr2} i\partial_t u - Δ^2 u - V(x) u + Q(x)

C. W. J. Beenakker, J. W. F. Venderbos, M. P. van Exter

We calculate the statistical distribution P_2(I_2) of the speckle pattern produced by a photon pair current I_2 transmitted through a random medium, and compare with the single-photon speckle distribution P_1(I_1). We show that the purity Tr rho^2 of a two-photon density matrix rho can be directly extracted from the first two moments of P_1 and P_2. A one-to

Christoph Leuenberger Daniel Wegmann Laurent Excoffier

Until recently, the use of Bayesian inference in population genetics was limited to a few cases because for many realistic population genetic models the likelihood function cannot be calculated analytically . The situation changed with the advent of likelihood-free inference algorithms, often subsumed under the term Approximate Bayesian Computation (ABC). A

H. Tashiro, T. Futamase

We investigate the weak gravitational lensing effect on the two-point correlation function of local maxima (hot spots) in the cosmic 21 cm fluctuation map. The intrinsic two-point function has a pronounced depression feature around the angular scale of $θ\sim 40$ arcmin, which depends on the observed frequency and corresponds to the scale of the acoustic osc

Ingrid-Maria Gregor

In this report the test beam requirements for the vertex detector and the tracking detector for ILC are discussed. It focuses on the infrastructure needs of the different subsystems. In the second part of this summary the ideas about future infrastructure above the immediate needs are summarised.

Florian Lipsmeier, Ellen Baake

The problem of \emph{statistical recognition} is considered, as it arises in immunobiology, namely, the discrimination of foreign antigens against a background of the body&#39;s own molecules. The precise mechanism of this foreign-self-distinction, though one of the major tasks of the immune system, continues to be a fundamental puzzle. Recent progress has b

M. Sanz, M. M. Wolf, D. Perez-Garcia, J. I. Cirac

We characterize the conditions under which a translationally invariant matrix product state (MPS) is invariant under local transformations. This allows us to relate the symmetry group of a given state to the symmetry group of a simple tensor. We exploit this result in order to prove and extend a version of the Lieb-Schultz-Mattis theorem, one of the basic re

F P Keenan, P J Crockett, K M Aggarwal, D B Jess

Aims: We generate theoretical ultraviolet and extreme-ultraviolet emission line ratios for O IV and show their strong versatility as electron temperature and density diagnostics for astrophysical plasmas. Methods: Recent fully relativistic calculations of radiative rates and electron impact excitation cross sections for O IV, supplemented with earlier data f

E. Cojocaru

Routines for computation of Weber&#39;s parabolic cylinder functions and their derivatives are implemented in Matlab for both moderate and great values of the argument. Standard, real solutions are considered. Tables of values are included.

K. L. Page, R. Willingale, P. T. O&#39;Brien, N. R. Tanvir

Swift-detected GRB 080307 showed an unusual smooth rise in its X-ray light-curve around 100 seconds after the burst, at the start of which the emission briefly softened. This `hump&#39; has a longer duration than is normal for a flare at early times and does not demonstrate a typical flare profile. Using a two component power-law-to-exponential model, the ri

Mohammad Hossein Yassaee, Mohammad Reza Aref

We present sufficient conditions for multicasting a set of correlated sources over cooperative networks. We propose joint source-Wyner-Ziv encoding/sliding-window decoding scheme, in which each receiver considers an ordered partition of other nodes. Subject to this scheme, we obtain a set of feasibility constraints for each ordered partition. We consolidate

Animesh Mukherjee, Monojit Choudhury, Ravi Kannan

Recent research has shown that language and the socio-cognitive phenomena associated with it can be aptly modeled and visualized through networks of linguistic entities. However, most of the existing works on linguistic networks focus only on the local properties of the networks. This study is an attempt to analyze the structure of languages via a purely str

A. Malizia, L. Bassani, F. Panessa, A. De Rosa

IGR J16351-5806 has been associated with the Seyfert 2 galaxy ESO 137-G34, having been first reported as a high energy emitter in the third INTEGRAL/IBIS survey. Using a new diagnostic tool based on X-ray column density measurements vs softness ratios, Malizia et al. (2007) identified this source as a candidate Compton thick AGN. In the present work we have

L. Pentericci, A. Grazian, A. Fontana

A significant fraction of high redshift starburst galaxies presents strong Ly alpha emission. Understanding the nature of these galaxies is important to assess the role they played in the early Universe and to shed light on the relation between the narrow band selected Lyalpha emitters and the Lyman break galaxies: are the Lyalpha emitters a subset of the ge

P. Szary, O. Petracic, H. Zabel

The magnetization reversal and spin structure in circular Co/insulator/Ni80Fe20 trilayer dots has been investigated numerically. The effect of dipolar coupling between a soft ferromagnetic Permalloy (Py=Ni80Fe20) layer and a hard ferromagnetic Cobalt layer inside one stack is studied. We find either a stabilization or even a triggering of the vortex state in

D. I. Kazakov

The present lectures are a practical guide to the calculation of radiative corrections to the Green functions in quantum field theory. The appearance of ultraviolet divergences is explained, their classification is given, the renormalization procedure which allows one to get the finite results is described, and the basis of the renormalization group in QFT i

M. Auvergne, P. Bodin, L. Boisnard, J. -T Buey

CoRoT is a space telescope dedicated to stellar seismology and the search for extrasolar planets. The mission is led by CNES in association with French laboratories and has a large international participation: the European Space Agency (ESA), Austria, Belgium and Germany contribute to the payload, and Spain and Brazil contribute to the ground segment. Develo

J. Crovisier, N. Biver, D. Bockelée-Morvan, J. Boissier

A fundamental question in cometary science is whether the different dynamical classes of comets have different chemical compositions, which would reflect different initial conditions. From the ground or Earth orbit, radio and infrared spectroscopic observations of a now significant sample of comets indeed reveal deep differences in the relative abundances of

Loïc Foissy

We introduce two operads which own the set of planar forests as a basis. With its usual product and two other products defined by different types of graftings, the algebra of planar rooted trees H becomes an algebra over these operads. The compatibility with the infinitesimal coproduct of H and these structures is studied. As an application, an inductive way

E. Akin, E. Glasner, W. Huang, S. Shao

Let (X,T) be a topologically transitive dynamical system. We show that if there is a subsystem (Y,T) of (X,T) such that (X\times Y, T\times T) is transitive, then (X,T) is strongly chaotic in the sense of Li and Yorke. We then show that many of the known sufficient conditions in the literature, as well as a few new results, are corollaries of this statement.

Brijesh Kumar Rai, Bikash Kumar Dey

We consider directed acyclic {\em sum-networks} with $m$ sources and $n$ terminals where the sources generate symbols from an arbitrary alphabet field $F$, and the terminals need to recover the sum of the sources over $F$. We show that for any co-finite set of primes, there is a sum-network which is solvable only over fields of characteristics belonging to t

L. P. Teo

In this article, we consider the finite temperature Casimir effect in Kaluza-Klein spacetime due the the vacuum fluctuation of massless scalar field with Dirichlet boundary conditions. We consider the general case where the extra dimensions (internal space) can be any compact connected manifold or orbifold without boundaries. Using piston analysis, we show t

Rui Zhang, John Cioffi

This paper studies a new decentralized resource allocation strategy, named iterative spectrum shaping (ISS), for the multi-carrier-based multiuser communication system, where two coexisting users independently and sequentially update transmit power allocations over parallel subcarriers to maximize their individual transmit rates. Unlike the conventional iter

Zhigen Zhao

In this paper, I apply the decision theory and empirical Bayesian approach to construct confidence intervals for selected populations when true parameters follow a mixture prior distribution. A loss function with two tuning parameters $k_1$ and $k_2$ is coined to address the mixture prior. One specific choice of $k_2$ can lead to the procedure in Qiu and Hwa

Ram Brustein, A. J. M. Medved

The near-horizon metric for a black brane in Anti-de Sitter (AdS) space and the metric near the AdS boundary both exhibit hydrodynamic behavior. We demonstrate the equivalence of this pair of hydrodynamic systems for the sound mode of a conformal theory. This is first established for Einstein&#39;s gravity, but we then show how the sound damping constant wil

Eun-Ha Kang, Hee-Won Lee, Byeong-Cheol Lee

We present the high resolution spectra of the youn and compact planerary nebula NGC 6790 obtained with the echelle spectrograph at Bohyunsan Optical Astronomy Observatory and report the discovery of Raman scattered He II 6545 in this object. This line feature is formed in a thick neutral region surrounding the hot central star, where He II 1025 line photons

Allen Knutson

Schwede proved very recently in arXiv:0901.1154 that in a quasiprojective scheme X with a fixed Frobenius splitting, there are only finitely many subschemes {Y} that are compatibly split. (A simpler proof has already since been given in arXiv:0901.2098, by Kumar and Mehta.) It follows that their deformations (as compatibly split subschemes) are obstructed. W

F. Aharonian

Very-high-energy (VHE; >~100 GeV) gamma-rays are expected from gamma-ray bursts (GRBs) in some scenarios. Exploring this photon energy regime is necessary for understanding the energetics and properties of GRBs. GRBs have been one of the prime targets for the H.E.S.S. experiment, which makes use of four Imaging Atmospheric Cherenkov Telescopes (IACTs) to det

Katsunori Kawamura, Yoshiki Hayashi, Dan Lascu

We show a correspondence between simple continued fraction expansions of irrational numbers and irreducible permutative representations of the Cuntz algebra ${\cal O}_{\infty}$. With respect to the correspondence, it is shown that the equivalence of real numbers with respect to modular transformations is equivalent to the unitary equivalence of representatio

Surajit Chattopadhyay, Ujjal Debnath

In this letter, we have considered that the universe is filled with normal matter and variable modified Chaplygin gas. Also we have considered the interaction between normal matter and variable modified Chaplygin gas in FRW universe. Then we have considered a correspondence between the holographic dark energy density and interacting variable modified Chaplyg

L. Grenet, M. Jamet, P. Noé, V. Calvo

In this letter, we show efficient electrical spin injection into a SiGe based \textit{p-i-n} light emitting diode from the remanent state of a perpendicularly magnetized ferromagnetic contact. Electron spin injection is carried out through an alumina tunnel barrier from a Co/Pt thin film exhibiting a strong out-of-plane anisotropy. The electrons spin polariz

H. Kuwahara, M. Akaki, J. Tozawa, M. Hitomi

We have investigated temperature and magnetic-field dependence of dielectric properties in the orthorhombic GdMnO$_3$ single crystal which is located near the phase boundary between the ferroelectric/spiral-antiferromagnetic phase and the paraelectric/$A$-type-antiferromagnetic one. In this compound, strong phase competition between these two phases results

Chang-Guang Shi, Minoru Hirayama

The interrelation between Ferreira&#39;s Hopf solitons of a conformal nonlinear $σ$ model and the electromagnetic knots found by Ra$\tilde{\rm{n}}$ada et al. is investigated. It is shown that the electromagnetic knots yield exact solutions of the conformal nonlinear $σ$ model different from those obtained by Ferreira. Conversely, It is discussed that Ferreir

Susumu Hirose

For the oriented 3-dimensional handlebody constructed from a 3-ball by attaching g 1-handles, it is shown that the natural surjection from the group of orientation preserving diffeomorphisms of it to the mapping class group of it has no section when g is at least 6.

Yue Shen, B. T. Draine, Eric T. Johnson

We study the light scattering properties of random ballistic aggregates constructed in Shen et al. (Paper I). Using the discrete-dipole-approximation, we compute the scattering phase function and linear polarization for random aggregates with various sizes and porosities, and with two different compositions: 100% silicate and 50% silicate-50% graphite. We in

Nazish Hoda, Mihailo R. Jovanović, Satish Kumar

Non-modal amplification of disturbances in streamwise-constant channel flows of Oldroyd-B fluids is studied from an input-output point of view by analyzing the responses of the velocity components to spatio-temporal body forces. These inputs into the governing equations are assumed to be harmonic in the spanwise direction and stochastic in the wall-normal di

Hidetsugu Sakaguchi

We perform molecular dynamics simulation of a small number of particles in a box with periodic boundary conditions from a view point of chaotic dynamical systems. There is a transition at a critical energy E_c that each particle is confined in each unit cell for E<E_c, and the chaotic diffusion occurs for E>E_c. We find an anomalous behavior of the jump freq

Xiang Zhou, KongFatt Wong-Lin, Philip Holmes

Several integrate-to-threshold models with differing temporal integration mechanisms have been proposed to describe the accumulation of sensory evidence to a prescribed level prior to motor response in perceptual decision-making tasks. An experiment and simulation studies have shown that the introduction of time-varying perturbations during integration may d

V. E. Didenko, A. S. Matveev, M. A. Vasiliev

We present unfolded description of AdS(4) black hole with generic parameters of mass, NUT, magnetic and electric charges as well as two kinematical parameters one of which is angular momentum. A flow with respect to black hole parameters, that relates the obtained black hole unfolded system to the covariant constancy condition for an AdS(4) global symmetry p

Ishani Roy, Jing-Mei Qiu, Chi-Wang Shu, Li-Zhi Fang

We develop a numerical solver for the integral-differential equations, which describes the radiative transfer of photon distribution in the frequency space with resonant scattering of Lyalpha photons by hydrogen gas in the early universe. The time-dependent solutions of this equation is crucial to the estimation of the effect of the Wouthuysen-Field (WF) cou

Ling Zhu, ShuangNan Zhang, Sumin Tang

We have decomposed the broad H-alpha, H-beta and H-gamma lines of 90 Active Galactic Nuclei (AGNs) into a superposition of a very broad and an intermediate Gaussian components (VBGC and IMGC) and discovered that the two Gaussian components evolve with FWHM of the whole emission lines. We suggest that the VBGC and the IMGC are produced in different emission r

Alwen Tiu

A notion of open bisimulation is formulated for the spi calculus, an extension of the pi-calculus with cryptographic primitives. In this formulation, open bisimulation is indexed by pairs of symbolic traces, which represent the history of interactions between the environment with the pairs of processes being checked for bisimilarity. The use of symbolic trac

T. Kotani, S. Lacour, G. Perrin, G. Robertson

The direct imaging and characterization of Earth-like planets is among the most sought-after prizes in contemporary astrophysics, however current optical instrumentation delivers insufficient dynamic range to overcome the vast contrast differential between the planet and its host star. New opportunities are offered by coherent single mode fibers, whose techn

Vinayak Nagpal, Sameer Pawar, David Tse, Borivoje Nikolic

Cooperation between terminals has been proposed to improve the reliability and throughput of wireless communication. While recent work has shown that relay cooperation provides increased diversity, increased multiplexing gain over that offered by direct link has largely been unexplored. In this work we show that cooperative multiplexing gain can be achieved

Q-Han Park

Optical antenna is a nanoscale miniaturization of radio or microwave antennas that is also governed by the rule of plasmonics. We introduce various types of optical antenna and make an overview of recent developments in optical antenna research. The role of local and surface plasmons in optical antenna is explained through antenna resonance and resonance con

Radha Krishna Ganti, Martin Haenggi

We consider a time-slotted two-hop wireless system in which the sources transmit to the relays in the even time slots (first hop) and the relays forward the packets to the destinations in the odd time slots (second hop). Each source may connect to multiple relays in the first hop. In the presence of interference and without tight coordination of the relays,

Nikesh S. Dattani

Recent developments in the interfacing of neurons with silicon chips may pave the way for progress in constructing scalable neurocomputers. The assembly of synthetic neuronal networks with predefined synaptic connections and controlled geometric structure has been realized experimentally within the last decade. Furthermore, when such neuronal networks are in

Nikolaos Kidonakis

I discuss heavy flavor production at hadronic facilities. I present total cross sections and differential distributions for top quark, bottom quark, and charm quark production at the Tevatron and LHC colliders, and at fixed-target experiments such as HERA-B. The calculations include complete next-to-leading order corrections as well as higher-order soft-gluo

S. Funk, J. A. Hinton

The current generation of Imaging Atmospheric telescopes (IACTs) has demonstrated the power of the technique in an energy range between ~100 GeV up to several tens of TeV. At the high-energy end, these instruments are limited by photon statistics. Future arrays of IACTs such as CTA or AGIS are planned to push into the energy range beyond 100 TeV. Scientifica

S. Funk, J. A. Hinton

The current generation of Imaging Atmospheric telescopes (IACTs) has demonstrated the power of this observational technique, providing high sensitivity and an angular resolution of $\sim0.1^{\circ}$ per event above an energy threshold of $\sim$100 GeV. Planned future arrays of IACTs such as AGIS or CTA are aiming at significantly improving the angular resolu