April 2008 arXiv papers — page 15

Smitha Vishveshwara, Courtney Lannert

We investigate the static and dynamic properties of bosonic lattice systems in which condensed and Mott insulating phases co-exist due to the presence of a spatially-varying potential. We formulate a description of these inhomogeneous systems and calculate the bulk energy at and near equilibrium. We derive the explicit form of the Josephson coupling between

R. Alvarez-Rodriguez, H. O. U. Fynbo, A. S. Jensen, E. Garrido

We discuss the three-body decay mechanisms of many-body resonances. Sequential decays proceed via two-body configurations after emission of the third particle. In direct decay all three particles leave simultaneously their interaction regions. The intermediate paths within the interaction regions are not observables and only accessible through models. The mo

A. Borras, M. Casas, A. R. Plastino, A. Plastino

We explore some basic entanglement features of multiqubit systems that are relevant for the development of algorithms for searching highly entangled states. In particular, we compare the behaviours of multiqubit entanglement measures based (i) on the von Neumann entropy of marginal density matrices and (ii) on the linear entropy of those matrices.

Konstantine Zelator

In the beginning of this paper, we present the general solution to the trigonometric equation asinx+bcosx=c. After that, we focus on the case when a^2+b^2=c^2. In this case, the general solution is expressed in terms of the acute angle theta which satisfies tan(theta)=a/b+c .From the right trianle with leglengths a and b, and hypotenuse length c, we construc

Oren Kurland, Lillian Lee

We present an approach to improving the precision of an initial document ranking wherein we utilize cluster information within a graph-based framework. The main idea is to perform re-ranking based on centrality within bipartite graphs of documents (on one side) and clusters (on the other side), on the premise that these are mutually reinforcing entities. Lin

S. Blondin, T. M. Davis, K. Krisciunas, B. P. Schmidt

We present multiepoch spectra of 13 high-redshift Type Ia supernovae (SNe Ia) drawn from the literature, the ESSENCE and SNLS projects, and our own separate dedicated program on the ESO Very Large Telescope. We use the Supernova Identification (SNID) code of Blondin & Tonry to determine the spectral ages in the supernova rest frame. Comparison with the obser

J. Mendez-Abreu, E. M. Corsini, Victor P. Debattista, S. De Rijcke

We present the results of high resolution absorption-line spectroscopy of 3 face-on galaxies, NGC 98, NGC 600, and NGC 1703 with the aim of searching for box/peanut (B/P)-shaped bulges. These observations test and confirm, for the first, time the prediction that face-on B/P-shaped bulges can be recognized by two minima in the profile along the bar's majo

A. P. Balachandran, A. Pinzul, A. R. Queiroz

In the absence of gauge fields, quantum field theories on the Groenewold-Moyal (GM) plane are invariant under a twisted action of the Poincare group if they are formulated following [1, 2, 3, 4, 5, 6]. In that formulation, such theories also have no UV-IR mixing [7]. Here we investigate UV-IR mixing in gauge theories with matter following the approach of [3,

S. -K. Lee

An ensemble of spins oriented along the $z$ direction exhibits nonzero fluctuation in the transverse ($x$- and $y$-) components of the spin angular momentum in accordance with the uncertainty principle. When the spins obey a spin temperature distribution, the mean square fluctuation in $S_{x}$ can be calculated by ensemble average of the expectation value of

Rico Zenklusen

In the matching interdiction problem, we are given an undirected graph with weights and interdiction costs on the edges and seek to remove a subset of the edges constrained to some budget, such that the weight of a maximum weight matching in the remaining graph is minimized. In this work we introduce the matching interdiction problem and show that it is stro

Graham Ellis, Roman Mikhailov

We recall a group-theoretic description of the first non-vanishing homotopy group of a certain (n+1)-ad of spaces and show how it yields several formulae for homotopy and homology groups of specific spaces. In particular we obtain an alternative proof of J. Wu's group-theoretic description of the homotopy groups of a 2-sphere.

Bao-An Li, Lie-Wen Chen, Che Ming Ko

The ultimate goal of studying isospin physics via heavy-ion reactions with neutron-rich, stable and/or radioactive nuclei is to explore the isospin dependence of in-medium nuclear effective interactions and the equation of state of neutron-rich nuclear matter, particularly the isospin-dependent term in the equation of state, i.e., the density dependence of t

Keitaro Takahashi

Several mechanisms have been proposed to generate primordial magnetic fields and it is often assumed that magnetic fields are not affected by a sharp drop in ionization rate due to the cosmic recombination. We investigate the validity of the assumption by studying the behavior of magnetic fields and fluid motion around recombination. Fluid equations includin

Caucher Birkar

Following Shokurov's ideas, we give a short proof of the following klt version of his result: termination of terminal log flips in dimension d implies that any klt pair of dimension d has a log minimal model or a Mori fibre space. Thus, in particular, any klt pair of dimension 4 has a log minimal model or a Mori fibre space.

Lorenzo N. Mazzoni, Lapo Casetti

A geometric analysis of the global properties of the energy landscape of a minimalistic model of a polypeptide is presented, which is based on the relation between dynamical trajectories and geodesics of a suitable manifold, whose metric is completely determined by the potential energy. We consider different sequences, some with a definite protein-like behav

G. Cocozza, F. R. Ferraro, A. Possenti, G. Beccari

We report on the optical identification of the companion to the eclipsing millisecond pulsar PSR J1701$-$3006B in the globular cluster NGC 6266. A relatively bright star with an anomalous red colour and an optical variability ($\sim$ 0.2 mag) that nicely correlates with the orbital period of the pulsar ($\sim$ 0.144 days) has been found nearly coincident wit

Jesse Miner, Jim Rose, Sheila Kannappan

We present a study of the relationship between the deficiency of neutral hydrogen and the local three-dimensional number density of spiral galaxies in the Arecibo catalog of global HI measurements (Springob et al. 2005). We find that the dependence on density of the HI content is weak at low densities, but increases sharply at high densities where interactio

John Ellis, N. E. Mavromatos, D. V. Nanopoulos

It has been suggested that energetic photons propagating in vacuo should experience a non-trivial refractive index due to the foamy structure of space-time induced by quantum-gravitational fluctuations. The sensitivity of recent astrophysical observations, particularly of AGN Mk501 by the MAGIC Collaboration, approaches the Planck scale for a refractive inde

Rubik Poghossian, Marine Samsonyan

In this paper we compute the partition function of 5D supersymmetric U(1) gauge theory with extra adjoint matter in general $Ω$-background. It is well known that such partition functions encode very rich topological information. We show in particular that unlike the case with no extra matter, the partition function with extra adjoint at some special values o

Stanley J. Brodsky, Guy F. de Teramond

Light-Front Holography is a remarkable consequence of the correspondence between string theory in AdS space and conformal field theories in physical-space time. It allows string modes $Φ(z)$ in the AdS fifth dimension to be precisely mapped to the light-front wavefunctions of hadrons in terms of a specific light-front impact variable $ζ$ which measures the s

Maurizio Fagotti, Pasquale Calabrese

The non-equilibrium evolution of the block entanglement entropy is investigated in the XY chain in a transverse magnetic field after the Hamiltonian parameters are suddenly changed from and to arbitrary values. Using Toeplitz matrix representation and multidimensional phase methods, we provide analytic results for large blocks and for all times, showing expl

Codruta Stoica

The paper emphasizes the properties of exponential dichotomy and exponential trichotomy for skew-evolution semiflows in Banach spaces, by means of evolution semiflows and evolution cocycles. The approach is from uniform point of view. Some characterizations which generalize classic results are also provided.

Christian Miebach

Let $X=G/K$ be an irreducible Hermitian symmetric space of the non-compact type and let $S\in G^\mbb{C}$ be the associated compression semi-group. Let $Γ$ be a discrete subgroup of $G$. We give a sufficient condition for $Γ\backslash S$ to be a Stein manifold. Moreover, we show that in general $Γ\backslash S$ is not Stein, which disproves a conjecture by Ach

B. Dybiec, E. Gudowska-Nowak, I. M. Sokolov

We consider the motion of an overdamped particle in a periodic potential lacking spatial symmetry under the influence of symmetric Lévy noise, being a minimal setup for a ``Lévy ratchet.'' Due to the non-thermal character of the Lévy noise, the particle exhibits a motion with a preferred direction even in the absence of whatever additional time-depen

J. Sykora, J. Vorel, T. Krejci, M. Sejnoha

Evaluation of effective or macroscopic coefficients of thermal conductivity under coupled heat and moisture transfer is presented. The paper first gives a detailed summary on the solution of a simple steady state heat conduction problem with an emphasis on various types of boundary conditions applied to the representative volume element -- a periodic unit ce

Marian F. Anton

We formulate a "correct" version of the Quillen conjecture on linear group homology for certain arithmetic rings and provide evidence for the new conjecture. In this way we predict that the linear group homology has a direct summand looking like an unstable form of Milnor K-theory and we call this new theory "homological symbols algebra". As

B. Jungnitsch, J. Evers

The realization of negative refraction in atomic gases requires a strong magnetic response of the atoms. Current proposals for such systems achieve an enhancement of the magnetic response by a suitable laser field configuration, but still rely on high gas densities. Thus further progress is desirable, and this requires an understanding of the precise mechani

Alexander Kiselev, Fedor Nazarov, Roman Shterenberg

The paper is a comprehensive study of the existence, uniqueness, blow up and regularity properties of solutions of the Burgers equation with fractional dissipation. We prove existence of the finite time blow up for the power of Laplacian $α< 1/2,$ and global existence as well as analyticity of solution for $α\geq 1/2.$ We also prove the existence of solution

Nathan Habegger, Jean-Baptiste Meilhan

We use an action, of 2l-component string links on l-component string links, defined by the first author and Xiao-Song Lin, to lift the indeterminacy of finite type link invariants. The set of links up to this new indeterminacy is in bijection with the orbit space of the restriction of this action to the stabilizer of the identity. Structure theorems for the

Rafael Ramirez, Carlos P. Herrero, Eduardo R. Hernandez, Manuel Cardona

Molecular dynamics simulations of 3C-SiC have been performed as a function of pressure and temperature. These simulations treat both electrons and atomic nuclei by quantum mechanical methods. While the electronic structure of the solid is described by an efficient tight-binding Hamiltonian, the nuclei dynamics is treated by the path integral formulation of s

V. P. Mineev

The symmetry approach to the description of the (P,T) phase diagram of ferromagnet superconductors with triplet pairing is developed. Taking into account the recent experimental observations made on UCoGe it is considered the case of a crystal with orthorhombic structure and strong spin-orbital coupling. It is shown that formation of ferromagnet superconduct

Gus L. W. Hart, Rodney W. Forcade

We present an algorithm for generating all derivative superstructures--for arbitrary parent structures and for any number of atom types. This algorithm enumerates superlattices and atomic configurations in a geometry-independent way. The key concept is to use the quotient group associated with each superlattice to determine all unique atomic configurations.

Fabio Sciarrino, Eleonora Nagali, Francesco De Martini, Miroslav Gavenda

Quantum entanglement, a fundamental property ensuring security of key distribution and efficiency of quantum computing, is extremely sensitive to decoherence. Different procedures have been developed in order to recover entanglement after propagation over a noisy channel. However, besides a certain amount of noise, entanglement is completely lost. In this ca

Martin Knor, Primoz Potocnik

We show that a 2-subset-regular self-complementary 3-uniform hypergraph with $n$ vertices exists if and only if $n\ge 6$ and $n$ is congruent to 2 modulo 4.

E. Kuznetsov, V. Krasnoselskikh

We consider the problem of spectra for acoustic type of turbulence generated by shocks being randomly distributed in space. We show that for turbulence with a weak anisotropy such spectra have the same dependence in $k$-space as the Kadomtsev-Petviashvili (KP) spectrum: $E(k)\sim k^{-2}$. However, the frequency spectrum has always the falling $\sim ω^{-2}$,

Alejandro Luque, Valeria Ratushnaya, Ute Ebert

We simulate short positive and negative streamers in air at standard temperature and pressure. They evolve in homogeneous electric fields or emerge from needle electrodes with voltages of 10 to 20 kV. The streamer velocity at given streamer length depends only weakly on the initial ionization seed, except in the case of negative streamers in homogeneous fiel

S. Prunet, C. Pichon, D. Aubert, D. Pogosyan

This technical paper describes a software package that was designed to produce initial conditions for large cosmological simulations in the context of the Horizon collaboration. These tools generalize E. Bertschinger&#39;s Grafic1 software to distributed parallel architectures and offer a flexible alternative to the Grafic2 software for ``zoom&#39;&#39; init

J. J. van der Bij

I discuss the question whether it is possible that the LHC will find no signal for the Higgs particle. It is argued that in this case singlet scalars should be present that could move in extra, even fractional, dimensions. A critical view at the existing electroweak data shows that this possibility might be favored over the simplest standard model. In this c

Andrea Alu, Mario G. Silveirinha, Nader Engheta

Following our recent interest in metamaterial-based devices supporting resonant tunneling, energy squeezing and supercoupling through narrow waveguide channels and bends, here we analyze the fundamental physical mechanisms behind this phenomenon using a transmission-line model. These theoretical findings extend our theory, allowing us to take fully into acco

Victor Romero, Enrique Cerda, T. A. Witten, Tao Liang

A thin fiber or sheet curled into a circular container has a detached region whose shape and force ratios are independent of material properties and container radius. We compute this shape and compare it with experiments. The discrete forces acting at either end of the detached region have a ratio that depends only on the length of the fiber or sheet relativ

Guang Ping He, Z. D. Wang

The relationship between the quantum bit commitment (QBC) and quantum seal (QS) is studied. It is elaborated that QBC and QS are not equivalent, but QS protocols satisfying a stronger unconditional security requirement can lead to an unconditionally secure QBC. In this sense, QS is strictly stronger than QBC in security requirements. Based on an earlier prop

Steven Detweiler

A small mass μin orbit about a much more massive black hole M moves along a world line that deviates from a geodesic of the black hole geometry by O(μ/M). This deviation is said to be caused by the gravitational self-force of the metric perturbation h_{ab} from μ. For circular orbits about a non-rotating black hole we numerically calculate the O(μ/M) effects

Julian Moosmann, Ralf Hofmann

We consider coarse-graining applied to nonselfintersecting planar center-vortex loops as they emerge in the confining phase of an SU(2) Yang-Mills theory. Well-established properties of planar curve-shrinking predict that a suitably defined, geometric effective action exhibits (mean-field) critical behavior when the conformal limit of circular points is reac

Hong-Xiang Wei, Jiexuan He, Zhen-Chao Wen, Xiu-Feng Han

We report the observation and micromagnetic analysis of current-driven magnetization switching in nanoscale ring-shaped magnetic tunnel junctions. When the electric current density exceeds a critical value of the order of $6\times 10^{6}$A/cm$^2$, the magnetization of the two magnetic rings can be switched back and forth between parallel and antiparallel oni

D. Moretti, N. Gonzalez, D. Felinto, J. W. R. Tabosa

We report on a detailed investigation of the dynamics and the saturation of a light grating stored in a sample of cold cesium atoms. We employ Bragg diffraction to retrieve the stored optical information impressed into the atomic coherence by the incident light fields. The diffracted efficiency is studied as a function of the intensities of both writing and

K. Lukierska-Walasek, K. Topolski

We use the Mandelbrot-Zipfs power law for the description of the inhomogenity of the spin system. We describe the statistical distributions of the domain&#39;s masses in the Ising model near the phase transition induced by the temperature. The statistical distribution near the critical point appears to be of the Pareto type.

Eva Manthey, Susanne Aalto, Susanne Huettemeister, Tom A. Oosterloo

NGC 4441 is a candidate for a merger between a spiral and an elliptical galaxy (S+E merger), because it shows typical tidal structures such as an optical tail and two shells. With a far-infrared luminosity of $\sim 5\cdot 10^9 L_{\odot}$ this galaxy belongs to the class of moderate luminosity mergers, in which the merging process induces (if at all) only a m

V. K. Magas, L. P. Csernai

The freeze out of the expanding systems, created in relativistic heavy ion collisions, is discussed. We combine kinetic freeze out equations with Bjorken type system expansion into a unified model. The important feature of the proposed scenario is that physical freeze out is completely finished in a finite time, which can be varied from 0 (freeze out hypersu

Markus Boettcher, Charles D. Dermer, Justin D. Finke

Observations of very-high-energy (VHE, E > 250 GeV) gamma-ray emission from several blazars at z > 0.1 have placed stringent constraints on the elusive spectrum and intensity of the intergalactic infrared background radiation (IIBR). Correcting their observed VHE spectrum for gamma-gamma absorption even by the lowest plausible level of the IIBR provided evid

Tapati Sarkar, Barnali Ghosh, A. K. Raychaudhuri, Tapan Chatterji

In this paper we report the structural and property (magnetic and electrical transport) measurements of nanocrystals of half-doped $\mathrm{La_{0.5}Ca_{0.5}MnO_3}$(LCMO) synthesized by chemical route, having particle size down to an average diameter of 15nm. It was observed that the size reduction leads to change in crystal structure and the room temperature

Sumiyoshi Abe, Norikazu Suzuki

The scaling relation derived by Dorogovtsev, Goltsev, Mendes and Samukhin [Phys. Rev. E, 68 (2003) 046109] states that the exponents of the power-law connectivity distribution, gamma, and the power-law eigenvalue distribution of the adjacency matrix, delta, of a locally treelike scale-free network satisfy 2*gamma - delta = 1 in the mean field approximation.

R. Kariyappa

Our aim is to identify and trace the X-ray Bright Points (XBPs) over the disk and use them as tracers to determine the coronal rotation. This investigation will help to clarify and understand several issues: whether (i) the corona rotates differentially; (ii) the rotation depends on the sizes of the XBPs; and (iii) dependence on phases of the solar magnetic

Fernando Hernando, Diego Ruano

Sixteen new linear codes are presented: three of them improve the lower bounds on the minimum distance for a linear code and the rest are an explicit construction of unknown codes attaining the lower bounds on the minimum distance. They are constructed using the Plotkin sum of two linear codes, also called $(u|u+v)$ construction. The computations have been a

Irinel Caprini

We investigate the determination of the $σ$ pole from $ππ$ scattering data below the $K\bar{K}$ threshold, including the new precise results obtained from $K_{e4}$ decay by NA48/2 Collaboration. We discuss also the experimental status of the threshold parameters $a_0^0$ and $b_0^0$ and the phase shift $δ_0^0$. In order to reduce the theoretical bias, we use

R. Kariyappa, L. Dame

Our aim is to search for atmospheric g-mode oscillations in UV network, UV bright points and Uv background regions. We have analysed a 6-hours of time sequence of ultraviolet (uv) images obtained on May 24, 2003 in 1600A continuum under high spatial and temporal resolution from Transition Region and Coronal Explorer (TRACE). We have selected an isolated 15 u

M. d&#39;Amico, P. Frosini, C. Landi

This paper studies the properties of a new lower bound for the natural pseudo-distance. The natural pseudo-distance is a dissimilarity measure between shapes, where a shape is viewed as a topological space endowed with a real-valued continuous function. Measuring dissimilarity amounts to minimizing the change in the functions due to the application of homeom

L. Martinez Alonso, E. Medina

Critical points of semiclassical expansions of solutions to the dispersionful Toda hierarchy are considered and a double scaling limit method of regularization is formulated. The analogues of the critical points characterized by the strong conditions in the Hermitian matrix model are analyzed and the property of doubling of equations is proved. A wide family

Dmitry Dolgopyat, Carlangelo Liverani

We consider a random walk with transition probabilities weakly dependent on an environment with a deterministic, but strongly chaotic, evolution. We prove that for almost all initial conditions of the environment the walk satisfies the CLT.

Diana Dorobantu

In this Note we study optimal stopping problems for strong Markov processes and affine functions. We give a justification of the Snell envelope form using standard results of optimal stopping. We also justify the convexity of the value function, and without a priori restriction to a particular class of stopping times, we deduce that the smallest optimal stop

Magali Rocher

Let k be an algebraically closed field of characteristic p>0 and C a connected nonsingular projective curve over k with genus g>1. Let (C,G) be a &#34;big action&#34;, i.e. a pair (C,G) where G is a p-subgroup of the k-automorphism group of C such that |G|/g > 2p / p-1. We first study finiteness results on the values taken by the quotient |G|/g^2 when (C,G)

Abha Dev, Deepak Jain, Daksh Lohiya

A power law cosmology is defined by the cosmological scale factor evolving as $t^α$. In this work, we put bounds on $α$ by using the joint test of the SNe Ia data from Supernova Legacy Survey (SNLS) and H(z) data with curvature constant $ k = 0, \pm 1$. We observe that the combined analysis with SNLS and H(z) data favours the open power cosmology with $α= 1.

C. M. Bender, D. C. Brody, H. F. Jones, B. K. Meister

In this brief comment we attempt to clarify the apparent discrepancy between the papers [1] and [2] on the quantum brachistochrone, namely whether it is possible to use a judicious mixture of Hermitian and non-Hermitian quantum mechanics to evade the standard lower limit on the time taken for evolution by a Hermitian Hamiltonian with given energy dispersion

Tony T. Lee, Lin Dai

This paper studies the buffered Aloha with K-exponential backoff collision resolution algorithms. The buffered Aloha network is modeled as a multi-queue single-server system. We adopt a widely used approach in packet switching systems to decompose the multi-queue system into independent first-in-first-out (FIFO) queues, which are hinged together by the proba

Daniel Campos, Josep E. Llebot, Vicenç Méndez

We present an agent-based model inspired by the Evolutionary Minority Game (EMG), albeit strongly adapted to the case of competition for limited resources in ecology. The agents in this game become able, after some time, to predict the a priori best option as a result of an evolution-driven learning process. We show that a self-segregated social structure ca

Karl-Hermann Neeb

In this note we introduce the concept of a semi-bounded unitary representations of an infinite-dimensional Lie group $G$. Semi-boundedness is defined in terms of the corresponding momentum set in the dual $\g&#39;$ of the Lie algebra $\g$ of $G$. After dealing with some functional analytic issues concerning certain weak-$*$-locally compact subsets of dual sp

A. M. Glauser, F. Ménard, C. Pinte, G. Duchêne

We present a study of the circumstellar environment of IRAS 04158+2805 based on multi-wavelength observations and models. Images in the optical and near-infrared, a polarisation map in the optical, and mid-infrared spectra were obtained with VLT-FORS1, CFHT-IR, and Spitzer-IRS. Additionally we used an X-ray spectrum observed with Chandra. We interpret the ob

N. Ghosh, U. K. Roessler, K. Nenkov, C. Hucho

Electrical transport and specific heat properties of Nd_{1-x}Pb_{x}MnO_{3} single crystals for 0.15 < x 0.5 have been studied in low temperature regime. The resistivity in the ferromagnetic insulating (FMI) phase for x < 0.3 has an activated character. The dependence of the activation gap Delta on doping x has been determined and the critical concentration f

A. Mallios, PP Ntumba

It is proved that for any free $\mathcal{A}$-modules $\mathcal{F}$ and $\mathcal{E}$ of finite rank on some $\mathbb{C}$-algebraized space $(X, \mathcal{A})$ a \textit{degenerate} bilinear $\mathcal{A}$-morphism $Φ: \mathcal{F}\times \mathcal{E}\longrightarrow \mathcal{A}$ induces a \textit{non-degenerate} bilinear $\mathcal{A}$-morphism $\barΦ: \mathcal{F}/

R. Kariyappa, B. A. Varghese

Our aim is to investigate the intensity oscillations in coronal X-ray Bright Points (XBPs). We analysed a 7-hours long time sequence of the soft X-ray images obtained on April 14, 2007 with 2-min cadence using X-Ray Telescope (XRT) on-board the Hinode mission. We use SSW in IDL to derive the time series of 14 XBPs and 2 background regions. For the first time

L. Lesniak

We show that the Flatte formula is not adequate to interpret precision data on a resonance production near an inelastic threshold. A unitary parameterization, satisfying generalized Watson&#39;s theorem for the production amplitudes, is proposed to replace the Flatte parameterization in phenomenological analyses of experimental data.

Stefan Thurner, Rudolf Hanel

Hilhorst and Schehr recently presented a straight forward computation of limit distributions of sufficiently correlated random numbers \cite{hilhorst}. Here we present the analytical form of entropy which --under the maximum entropy principle (with ordinary constraints)-- provides these limit distributions. These distributions are not $q$-Gaussians and can n

J. Durand, B. Juliá-Díaz, T. -S. H. Lee, B. Saghai

The reaction $π^{-}p \to ηn$ is investigated within a dynamical coupled-channels model of meson production reactions in the nucleon resonance region. The meson baryon channels included are $πN$, $ηN$, $πΔ$, $σN$, and $ρN$. The non-resonant meson-baryon interactions of the model are derived from a set of Lagrangians by using a unitary transformation method. O

Damir Valiev, Vitaly Bychkov, V&#39;yacheslav Akkerman, Lars-Erik Eriksson

The role of viscous stress in heating of the fuel mixture in deflagration-to-detonation transition in tubes is studied both analytically and numerically. The analytical theory is developed in the limit of low Mach number; it determines temperature distribution ahead of an accelerating flame with maximum achieved at the walls. The heating effects of viscous s

Shiv K Sethi, Biman B. Nath, Kandaswamy Subramanian

We study the implications of primordial magnetic fields for the thermal and ionization history of the post-recombination era. In particular we compute the effects of dissipation of primordial magnetic fields owing to ambipolar diffusion and decaying turbulence in the intergalactic medium (IGM) and the collapsing halos and compute the effects of the altered t

Biman B. nath, Tanmoy Laskar, J. Michael Shull

We consider sputtering of dust grains, believed to be formed in cooling supernovae ejecta, under the influence of reverse shocks. In the regime of self-similar evolution of reverse shocks, we can follow the evolution of ejecta density and temperature analytically as a function of time in different parts of the ejecta, and calculate the sputtering rate of gra

M. Cirasuolo, R. J. McLure, J. S. Dunlop, O. Almaini

We present the most accurate measurement to date of cosmological evolution of the near-infrared galaxy luminosity function, from the local Universe out to z~4. The analysis is based on a large and highly complete sample of galaxies selected from the first data release of the UKIDSS Ultra Deep Survey. Exploiting a master catalogue of K- and z-band selected ga

Ryo Saito, Jun&#39;ichi Yokoyama, Ryo Nagata

We show a text-book potential for single-field inflation, namely, the Coleman-Weinberg model can induce double inflation and formation of primordial black holes (PBHs), because fluctuations that leave the horizon near the end of first inflation are anomalously enhanced at the onset of second inflation when the time-dependent mode turns to a growing mode rath

Thomas Creutzig, Volker Schomerus

We investigate correlation functions for maximally symmetric boundary conditions in the WZNW model on GL(1|1). Special attention is payed to volume filling branes. Generalizing earlier ideas for the bulk sector, we set up a Kac-Wakimoto-like formalism for the boundary model. This first order formalism is then used to calculate bulk-boundary 2-point functions

Biman B. Nath

The distribution of luminous radio galaxies in galaxy clusters has been observed to be concentrated in the inner region. We consider the role of dynamical friction of massive galaxies ($M\sim 10^{12.5}$ M$_{\odot}$), assuming them to be hosts of luminous radio galaxies, and show that beginning with a Navarro-Frenk-White density profile of a cluster of mass $

Pierre Kervella, Armando Domiciano De Souza, Philippe Bendjoya

Context: Be stars are massive dwarf or subgiant stars that present temporary emission lines in their spectrum, and particularly in the Halpha line. The mechanism triggering these Be episodes is currently unknown, but binarity could play an important role. Aims: Previous observations with the VLT/VISIR instrument (Kervella & Domiciano de Souza 2007) revealed

Michael K Murray, Danny Stevenson

We consider the construction of the basic bundle gerbe on SU(n) introduced by Meinrenken and show that it extends to a range of groups with unitary actions on a Hilbert space including U(n), diagonal tori and the Banach Lie group of unitary operators differing from the identity by an element of a Schatten ideal. In all these cases we give an explicit connect

A. Senorita Devi, R. Misra, K. Shanthi, K. Y. Singh

We report variability of the X-ray source, X-7, in NGC 6946, during a 60 ksec Chandra observation when the count rate decreased by a factor of ~1.5 in ~5000 secs. Spectral fitting of the high and low count rate segments of the light curve reveal that the simplest and most probable interpretation is that the X-ray spectra are due to disk black body emission w

Xi-Jun Ren, Wei Jiang, Xingxiang Zhou, Zheng-Wei Zhou

In this work we consider the permutational properties of multipartite entanglement monotones. Based on the fact that genuine multipartite entanglement is a property of the entire multi-qubit system, we argue that ideal definitions for its characterizing quantities must be permutation-invariant. Using this criterion, we examine the three 4-qubit entanglement

J. Wang, I. Cotoros, X. Liu, J. Chovan

We report a femtosecond response in photoinduced magnetization rotation in the ferromagnetic semiconductor GaMnAs, which allows for detection of a four-state magnetic memory at the femtosecond time scale. The temporal profile of this cooperative magnetization rotation exhibits a discontinuity that reveals two distinct temporal regimes, marked by the transiti

I. van der Werf, F. Palmisano, R. De Leo, S. Marrone

After five years of operating, two Aerogel counters: A1 and A2, taking data in Hall A at Jefferson Lab, suffered a loss of performance. In this note possible causes of degradation have been studied. In particular, various chemical and physical analyses have been carried out on several Aerogel tiles and on adhesive tape in order to reveal the presence of cont

M. J. Calderon, J. Salafranca, L. Brey

We study theoretically the magnetic and electric properties of the interface between two antiferromagnetic and insulating manganites: La0.5Ca0.5MnO3, a strong correlated insulator, and CaMnO3, a band-insulator. We find that a ferromagnetic and metallic electron gas is formed at the interface between the two layers. We confirm the metallic character of the in

Lan Zhang, Yan Xin, Ying-Chang Liang

In this paper, we consider a cognitive radio (CR) network in which the unlicensed (secondary) users are allowed to concurrently access the spectrum allocated to the licensed (primary) users provided that their interference to the primary users (PUs) satisfies certain constraints. We study a weighted sum rate maximization problem for the secondary user (SU) m

Masashi Ishida, Hirofumi Sasahira

We shall prove a new non-vanishing theorem for the stable cohomotopy Seiberg-Witten invariant of connected sums of 4-manifolds with positive first Betti number. The non-vanishing theorem enables us to find many new examples of 4-manifolds with non-trivial stable cohomotopy Seiberg-Witten invariants and it also gives a partial, but strong affirmative answer t

Venta Terauds

In this note, we show that if a Banach space X has a predual, then every bounded linear operator on X with a continuous functional calculus admits a bounded Borel functional calculus. A consequence of this is that on such a Banach space, the classes of finitely spectral and prespectral operators coincide. We also apply this result to give some sufficient con

D. V. Bugg

The formulae needed to parametrise sigma, kappa, a0(980) and f0(980) are reviewed. For sigma and kappa, the Adler zero due to Chiral Symmetry Breaking plays a crucial role. The f0(980) and a0(980) are locked to the KK threshold by a cusp mechanism which leads to a sharp peak in attraction at the threshold. This mechanism may play a wider role. A novel sugges

David Pask, Iain Raeburn, Natasha A. Weaver

Higher-rank graphs (or $k$-graphs) were introduced by Kumjian and Pask to provide combinatorial models for the higher-rank Cuntz-Krieger $C^*$-algebras of Robertson and Steger. Here we consider a family of finite 2-graphs whose path spaces are dynamical systems of algebraic origin, as studied by Schmidt and others. We analyse the $C^*$-algebras of these 2-gr

R. Parthasarathy, K. S. Viswanathan

We have considered the holographic large $N_c$ QCD model proposed by Sakai and Sugimoto and evaluated the non-Abelian DBI-action on the D8-brane upto $(α&#39;)^4$ terms. Restricting to the pion sector, these corrections give rise to four derivative contact terms for the pion field. We derive the Weinberg&#39;s phenemenological lagrangian. The coefficients of

P. Reig, T. Belloni, G. L. Israel, S. Campana

We have performed a timing and spectral analysis of the X-ray pulsar SWIFT J1626.6-5156 during a major X-ray outburst in order to unveil its nature and investigate its flaring activity. Epoch- and pulse-folding techniques were used to derive the spin period. Time-average and pulse-phase spectroscopy were employed to study the spectral variability in the flar

Nikos Kalogeropoulos

We perform a calculation of the first and second order infinitesimal variations, with respect to energy, of the Boltzmann entropy of constant energy hypersurfaces of a system with a finite number of degrees of freedom. We comment on the stability interpretation of the second variation in this framework.

K. Grove-Rasmussen, H. I. Jørgensen, T. Hayashi, P. E. Lindelof

A top-gated single wall carbon nanotube is used to define three coupled quantum dots in series between two electrodes. The additional electron number on each quantum dot is controlled by top-gate voltages allowing for current measurements of single, double and triple quantum dot stability diagrams. Simulations using a capacitor model including tunnel couplin

Bo Gu, Nejat Bulut, Sadamichi Maekawa

We study the ferromagnetism in the compound (Zn,Mn)O within the Haldane-Anderson impurity model by using the quantum Monte Carlo technique and the tight-binding approximation for determining the host band-structure and the impurity-host hybridization. This computational approach allows us to determine how the host crystal structure influences the impurity bo

Maria E. Tejeda-Yeomans, Jorge Navarro, Angel Sanchez, Gabriella Piccinelli

The study of the universe&#39;s primordial plasma at high temperature plays an important role when tackling different questions in cosmology, such as the origin of the matter-antimatter asymmetry. In the Minimal Standard Model (MSM) neither the amount of CP violation nor the strength of the phase transition are enough to produce and preserve baryon number du

Siavash Ekbatani, Hamid Jafarkhani

The goal of combining beamforming and space-time coding in this work is to obtain full-diversity order and to provide additional received power (array gain) compared to conventional space-time codes. In our system, we consider a quasi-static fading environment and we incorporate both high-rate and low-rate feedback channels with possible feedback errors. To

Wei Chen, Manu Sharma, Raffaele Resta, Giulia Galli

We report simulated infrared spectra of deuterated water and ice using Car-Parrinello molecular dynamics with maximally localized Wannier functions. Experimental features are accurately reproduced within the harmonic approximation. By decomposing the lineshapes in terms of intra and intermolecular dipole correlation functions we find that short-range intermo

Stefano Meschiari, Gregory Laughlin

In this letter, we briefly describe the evolution of a variety of self-gravitating protoplanetary disk models that contain annular grooves (e.g. gaps) in their surface density. These grooves are inspired by the density gaps that are presumed to open in response to the formation of a giant planet. Our work provides an extension of the previously studied groov