July 2006 arXiv papers — page 38

Luca Sguanci, Pietro Lio', Franco Bagnoli

Our work stems from the consideration that the spreading of a disease is modulated by the individual's perception of the infected neighborhood and his/her strategy to avoid being infected as well. We introduced a general ``cellular agent'' model that accounts for a hetereogeneous and variable network of connections. The probability of infection i

Ryan M. Camacho, Michael V. Pack, John C. Howell

We consider group delay and broadening using two strongly absorbing and widely spaced resonances. We derive relations which show that very large pulse bandwidths coupled with large group delays and small broadening can be achieved. Unlike single resonance systems, the dispersive broadening dominates the absorptive broadening which leads to a dramatic increas

Luca Dall'Asta, Andrea Baronchelli, Alain Barrat, Vittorio Loreto

The Naming Game is a model of non-equilibrium dynamics for the self-organized emergence of a linguistic convention or a communication system in a population of agents with pairwise local interactions. We present an extensive study of its dynamics on complex networks, that can be considered as the most natural topological embedding for agents involved in lang

Miroslaw Kozlowski, Janina Marciak-Kozlowska

In this paper we investigate the diffusion of the thermal pulse in Planck Gas. We show that the Fourier diffusion equation gives the speed of diffusion, v > c and breaks the causality of the thermal processes in Planck gas .For hyperbolic heat transport v<c and causality is valid

Xiaodong Yang, Chee Wei Wong

We demonstrate the dynamics of stimulated Raman scattering in designed high-Q/Vm silicon photonic band gap nanocavities through the coupled-mode theory framework towards optically-pumped silicon lasing. The interplay of other chi(3) effects such as two-photon absorption and optical Kerr, related free-carrier dynamics, thermal effects, as well as linear losse

J. M. Aguirregabiria, A. Hernández, M. Rivas

We analyze a simple problem in elasticity: the \emph{initial} motion of an elastic bar that after being hanged from an end is suddenly released. In a second problem a point mass is attached on the top of the bar. The analytical solutions uncover some unexpected properties, which can be checked, with a digital camera or camcorder, in an alternative setup in w

J. R. Mureika

An interdisciplinary physical theory of emergent consciousness has previously been proposed, stemming from quantum computation-like behavior between 10^9 or more entangled molecular qubit states (microtubulin). This model relies on the Penrose-Diosi gravity-driven wavefunction collapse framework, and thus is subject to any secondary classical and quantum gra

R. J. de Meijer, F. D. Smit, F. D. Brooks, R. W. Fearick

The programme Earth AntineutRino TomograpHy (EARTH) proposes to build ten underground facilities each hosting a telescope. Each telescope consists of many detector modules, to map the radiogenic heat sources deep in the interior of the Earth by utilising direction sensitive geoneutrino detection. Recent hypotheses target the core-mantle boundary (CMB) as a m

Bernhard Rothenstein, Stefan Popescu

Following an approach proposed by Rosser for deriving the transformation equations of volume charge density and current density we derive the transformation equations for the space-time coordinates of the same event, for the mass and the momentum of the same particle and for the electric and the magnetic field generated by the same distribution of electric c

A. Ya. Bekshaev

Expressions are obtained for the Wigner function moments of a paraxial light beam represented by arbitrary coherent superposition of Hermite-Gaussian beams with plane wave fronts. Possibilities are discussed for application of the obtained results to modeling real laser beams and to design of optical systems implementing prescribed transformations of a beam

Hong Zhao, Tao Jin

We present a global algorithm for training multilayer neural networks in this Letter. The algorithm is focused on controlling the local fields of neurons induced by the input of samples by random adaptations of the synaptic weights. Unlike the backpropagation algorithm, the networks may have discrete-state weights, and may apply either differentiable or nond

K. K. Gudima, S. G. Mashnik

The Los Alamos version of the Quark-Gluon String Model implemented in the code LAQGSM03 was extended to describe photonuclear reactions at energies up to tens of GeV. We have incorporated 56 channels to consider gamma+p elementary interactions during the cascade stage of reactions and 56 channels for gamma+n interactions, in addition to absorption of photons

Govind Menon, Robert L. Pego

We establish necessary and sufficient conditions for the shock statistics to approach self-similar form in Burgers turbulence with Lévy process initial data. The proof relies upon an elegant closure theorem of Bertoin and Carraro and Duchon that reduces the study of shock statistics to Smoluchowski&#39;s coagulation equation with additive kernel, and upon ou

Yacine Amarouchene, Daniel Bonn, Hamid Kellay, Ting-Shek Lo

We present experimental and theoretical results addressing the Reynolds number (Re) dependence of drag reduction by sufficiently large concentrations of rod-like polymers in turbulent wall-bounded flows. It is shown that when Re is small the drag is {\em enhanced}. On the other hand when Re increases the drag is reduced and eventually the Maximal Drag Reduct

M. C. Navarro, A. M. Mancho, H. Herrero

We study from the numerical point of view, instabilities developed in a fluid layer with a free surface, in a cylindrical container which is non-homogeneously heated from below. In particular we consider the case in which the applied heat is localized around the origin. An axysimmetric basic state appears as soon a non-zero horizontal temperature gradient is

Nasir Ganikhodjaev, Farrukh Mukhamedov, Jose F. F. Mendes

In the present paper the three state Potts model with competing binary interactions (with couplings $J$ and $J_p$) on the second order Bethe lattice is considered. The recurrent equations for the partition functions are derived. When $J_p=0$, by means of a construction of a special class of limiting Gibbs measures, it is shown how these equations are related

Janet Striuli

In this note we give a simple proof of the fact that local rings of dimension one have the strong uniform Artin-Rees property. Moreover, we give two examples of rings of dimension two where the property fails.

Dimitri Bormotov, Robert Gilman, Alexei Myasnikov

Equations in free groups have become prominent recently in connection with the solution to the well known Tarski Conjecture. Results of Makanin and Rasborov show that solvability of systems of equations is decidable and there is a method for writing down in principle all solutions. However, no practical method is known; the best estimate for the complexity o

Geoffrey L. Price, Shoichuro Sakai

Let Γbe the convex set consisting of all marginal tracial states on the tensor product B \otimes B of the algebra B of nxn matrices over the complex numbers. We find necessary and sufficient conditions for such a state to be extremal in Γ. We also give a characterization of those extreme points in Γwhich are pure states. We conjecture that all extremal margi

Klaus Altmann, Georg Hein

We study the relation between projective T-varieties and their affine cones in the language of the so-called divisorial fans and polyhedral divisors. As an application, we present the Grassmannian Grass(2,n) as a ``fansy divisor&#39;&#39; on the moduli space of stable, n-pointed, rational curves.

Alexander Kelmans

We give a simple proof of MacLane&#39;s algebraic planarity criterion for graphs. This proof does not use any other known planarity criteria. Keywords: graph, planarity, cycle space, a simple basis of a graph.

Gaiane Panina

We wish to draw attention to an interesting and promising interaction of two theories. On the one hand, it is the theory of \textbf{pseudo-triangulations} which was useful for implicit solution of thecarpenter&#39;s rule problem and proved later to give a nice tool for graph embeddings. On the other hand, it is the theory of hyperbolic virtual polytopes whic

K. A. Brown, I. G. Gordon, C. H. Stroppel

We show how the existence of a PBW-basis and a large enough central subalgebra can be used to deduce that an algebra is Frobenius. This is done by considering the examples of rational Cherednik algebras, Hecke algebras, quantised universal enveloping algebras, quantum Borels and quantised function algebras. In particular, we give a positive answer to \cite[P

M. Z. Garaev, V. C. Garcia, S. V. Konyagin

Let $τ(n)$ be the Ramanujan $τ$-function. We prove that for any integer $N$ the diophantine equation $$ \sum_{i=1}^{74000}τ(n_i)=N $$ has a solution in positive integers $n_1, n_2,..., n_{74000}$ satisfying the condition $$ \max_{1\le i\le 74000}n_i\ll |N|^{2/11}+1. $$ We also consider similar questions in the residue ring modulo a large prime $p.$

Werner Hurlimann

On the occasion of the 125-th anniversary of Newcomb&#39;s paper, a bibliography of academic work related to Benford&#39;s law from its year of origin 1881 to 2006 has been compiled.

Werner Hurlimann

A simple method to derive parametric analytical extensions of Benford&#39;s law for first digits of numerical data is proposed. Two generalized Benford distributions are considered, namely the two-sided power Benford distribution and the new Pareto Benford distribution. The fitting capabilities of these generalized Benford distributions are illustrated and c

R. Cluckers, M. Edmundo

Following recent work of R. Cluckers and F. Loeser [Fonctions constructible et integration motivic I, C. R. Math. Acad. Sci. Paris 339 (2004) 411 - 416] on motivic integration, we develop a direct image formalism for positive constructible functions in the globally subanalytic context. This formalism is generalized to arbitrary first-order logic models and i

Alexei Panchishkin

We discuss modular forms as objects of computer algebra and as elements of certain p-adic Banach modules. Problem-solving approach in number theory is discussed which is based on the use of generating functions and their links with modular forms. In particular, the critical values of various L-functions of modular forms produce non-trivial but computable sol

Craig Huneke, Mordechai Katzman, Rodney Y. Sharp, Yongwei Yao

This paper studies Frobenius powers of parameter ideals in a commutative Noetherian local ring $R$ of prime characteristic $p$. For a given ideal $\fa$ of $R$, there is a power $Q$ of $p$, depending on $\fa$, such that the $Q$-th Frobenius power of the Frobenius closure of $\fa$ is equal to the $Q$-th Frobenius power of $\fa$. The paper addresses the questio

Daniel Soll, Volkmar Welker

For $n\geq 3$, let $Ω_n$ be the set of line segments between the vertices of a convex $n$-gon. For $j\geq 2$, a $j$-crossing is a set of $j$ line segments pairwise intersecting in the relative interior of the $n$-gon. We identify line-segments in $Ω_{2n}$ which can be transformed into each other by a $180^\circ$-rotation of the $2n$-gon. Let $\F_n$ be the se

Sundaram Thangavelu

We formulate and prove a version of Paley-Wiener theorem for the inverse Fourier transform on non-compact Riemannian symmetric spaces and Heisenberg groups. The main ingredient in the proof is the Gutzmer&#39;s formula.

Victor Bovdi

Let K be a field of positive characteristic p and KG the group algebra of a group G. It is known that, if KG is Lie nilpotent, then its upper (or lower) Lie nilpotency index is at most |G&#39;|+1, where |G&#39;| is the order of the commutator subgroup. Previously we determined the groups G for which the upper/lower nilpotency index is maximal or the upper ni

Marco Avarucci, Domenico Marinucci

n this paper we consider polynomial cointegrating relationships among stationary processes with long range dependence. We express the regression functions in terms of Hermite polynomials and we consider a form of spectral regression around frequency zero. For these estimates, we establish consistency by means of a more general result on continuously averaged

Jouko Mickelsson, Sylvie Paycha

We provide local expressions for Chern-Weil type forms built from superconnections associated with families of Dirac operators previously investigated in work by S. Scott and later work by S. Scott and the second author. When the underlying fibration of manifolds is trivial, the even degree forms can be interpreted as renormalised Chern-Weil forms in as far

Pierre-André Zitt

We consider a continuous analogue of the simulated annealing algorithm in $R^d$. We prove a convergence result, under hypotheses weaker than the usual ones. In particular, we cover cases where the gradient of the potential goes to zero at infinity. The proof follows an idea of L. Miclo, but we replace the Poincar\'e and log-Sobolev inequalities (which do not

Matthew M. Peet

This thesis addresses the question of stability of systems defined by differential equations which contain nonlinearity and delay. In particular, we analyze the stability of a well-known delayed nonlinear implementation of a certain Internet congestion control protocol. We also describe a generalized methodology for proving stability of time-delay systems th

A. N. Dranishnikov, J. Smith

For a large class of metric space X including discrete groups we prove that the asymptotic Assouad-Nagata dimension AN-asdim X of X coincides with the covering dimension $\dim(ν_L X)$ of the Higson corona of X with respect to the sublinear coarse structure on X. Then we apply this fact to prove the equality AN-asdim(X x R) = AN-asdim X + 1. We note that the

Arnaud Debussche, Cyril Odasso

We construct a Markov family of solutions for the 3D Navier-Stokes equation perturbed by a non degenerate noise. We improve the result of [DPD-NS3D] in two directions. We see that in fact not only a transition semigroup but a Markov family of solutions can be constructed. Moreover, we consider a state dependant noise. Another feature of this work is that we

Cyril Odasso

We consider stationary solutions of the three dimensional Navier--Stokes equations (NS3D) with periodic boundary conditions and driven by an external force which might have a deterministic and a random part. The random part of the force is white in time and very smooth in space. We investigate smoothness properties in space of the stationary solutions. Class

Cyril Odasso

We study the Navier-Stokes equations in dimension 3 (NS3D) driven by a noise which is white in time. We establish that if the noise is at same time sufficiently smooth and non degenerate in space, then the weak solutions converge exponentially fast to equilibrium. We use a coupling method. The arguments used in dimension two do not apply since, as is well kn

Ron M. Adin, Francesco Brenti, Yuval Roichman

An axiomatic approach to the representation theory of Coxeter groups and their Hecke algebras was presented in [1]. Combinatorial aspects of this construction are studied in this paper. In particular, the symmetric group case is investigated in detail. The resulting representations are completely classified and include the irreducible ones.

Pavlos B. Konstadinidis

In this work, we introduce another extension U of the 3n+1 function to the real line. We propose a conjecture about the U-trajectories that generalizes the famous 3n+1 (or Collatz) conjecture. We then prove our main result about the iterates of U (which is directly related to both of these conjectures). We also introduce the &#34;flipped 3x+1&#34; function \

Arnaud Debussche, Cyril Odasso

We study a damped stochastic non-linear Schrödinger (NLS) equation driven by an additive noise. It is white in time and smooth in space. Using a coupling method, we establish convergence of the Markovian transition semi-group toward a unique invariant probability measure. This kind of method was originally developped to prove exponential mixing for strongly

Cyril Odasso

We study a stochastic complex Ginzburg--Landau (CGL) equation driven by a smooth noise in space and we establish exponential convergence of the Markovian transition semi-group toward a unique invariant probability measure. Since Doob Theorem does not seem not to be useful in our situation, a coupling method is used. In order to make this method easier to und

Jarah Evslin, Hisham Sati

Sometimes a homology cycle of a nonsingular compactification manifold cannot be represented by a nonsingular submanifold. We want to know whether such nonrepresentable cycles can be wrapped by D-branes. A brane wrapping a representable cycle carries a K-theory charge if and only if its Freed-Witten anomaly vanishes. However some K-theory charges are only car

G. Benfatto, P. Falco, V. Mastropietro

We present the first rigorous construction of the QFT Thirring model, for any value of the mass, in a functional integral approach, by proving that a set of Grassmann integrals converges, as the cutoffs are removed, to a set of Schwinger functions verifying the Osterwalder-Schrader axioms. The massless limit is investigated and it is shown that the Schwinger

Philip D. Mannheim

For the Randall-Sundrum brane world where a positive tension Minkowski brane is embedded in AdS5, two candidate propagators have been suggested in the literature, one being based on the normalized mode solutions to the source-free volcano potential fluctuation equation, and the other being the Giddings, Katz and Randall outgoing Hankel function based one. We

Inyong Cho, Eung Jin Chun, Hang Bae Kim, Yoonbai Kim

The D-brane world is an idea that we are living on the D-brane imbedded in a 10- or 11-dimensional spacetime of string theories, aiming at the construction of realistic models from string theories. We investigate the cosmological aspects of the D-brane world, focusing on homogeneous anisotropic cosmology driven by the dilaton and the NS-NS 2-form field which

Dominic Joyce

Let X be a Calabi-Yau 3-fold, T=D^b(coh(X)) the derived category of coherent sheaves on X, and Stab(T) the complex manifold of Bridgeland stability conditions Z on T. It is conjectured that one can define rational numbers J^a(Z) for Z in Stab(T) and a in the numerical Grothendieck group K(T) generalizing Donaldson-Thomas invariants, which `count&#39; Z-semis

Matteo Cacciari

Two main classes of jet clustering algorithms, cone and k_t, are briefly discussed. It is argued that the former can be often cumbersome to define and implement, and difficult to analyze in terms of its behaviour with respect to soft and collinear emissions. The latter, on the other hand, enjoys a very simple definition, and can be easily shown to be infrare

Alexander A. Osipov, Brigitte Hiller, Alex H. Blin, Joao da Providencia

The combined effective low energy QCD Lagrangians of Nambu -- Jona-Lasinio (NJL) and &#39;t Hooft are supplemented with eight-quark interactions. This work is a follow-up of recent findings, namely (i) the six quark flavour determinant &#39;t Hooft term destabilizes the NJL vacuum, (ii) the addition of a chiral invariant eight-fermion contact term renders th

Jorgen Randrup, Jean Cleymans

Using simple parametrizations of the thermodynamic freeze-out parameters extracted from the data over a wide beam-energy range, we reexpress the hadronic freeze-out line in terms of the underlying dynamical quantities, the net baryon density rhoB and the energy density epsilon, which are subject to local conservation laws. This analysis makes it apparent tha

Yutaka Hosotani

In the dynamical gauge-Higgs unification, it is shown that the mass of the Higgs boson (4D scalar field) in U(1) gauge theory in $M^4 \times T^n$ ($n=1,2,3,...$) is finite to all order in perturbation theory as a consequence of the large gauge invariance. It is conjectured that the Higgs boson mass is finite in non-Abelian gauge theory in $M^4 \times S^1$, $

M. Hirai, S. Kumano, N. Saito

We investigate the polarized gluon distribution Δg(x) by a global analysis of current DIS data and the π^0 data from RHIC-Spin experiments. The π^0 data provide a strong constraint on Δg(x), so that its uncertainty is reduced. Furthermore, new DIS data of COMPASS and HERMES play an important role in determining Δg(x) at large x.

Hai-Yang Cheng

An overview of exclusive two-body and three-body baryonic B decays is given. The threshold enhancement effect in the dibaryon invariant mass and the angular distributions in the dibaryon rest frame are stressed and explained. Weak radiative baryonic B decays mediated by the electromagnetic penguin process $b\to sγ$ are discussed. Apart from the first observa

A. Bredenstein, A. Denner, S. Dittmaier, M. M. Weber

Extending earlier work, we provide predictions obtained with the Monte Carlo generator PROPHECY4f for the decays H-->ZZ/WW-->4l including the complete electroweak O(alpha) corrections and some higher-order improvements. The gauge-boson resonances are described in the complex-mass scheme. Here, particular attention is paid to a comparison of different final s

G. J. Gounaris, J. Layssac, F. M. Renard

We present a complete analysis of the one loop electroweak corrections to $e^-e^+\toγγ, ~Zγ, ~ZZ$ in the Standard (SM) and the Minimal Supersymmetric Standard Model (MSSM). Analytic expressions are written for the contributions to the helicity amplitudes. Several observables accessible for polarized or unpolarized beams and transverse, longitudinal or unpola

David Brizuela, Jose M. Martin-Garcia, Guillermo A. Mena Marugan

The Gerlach and Sengupta (GS) formalism of coordinate-invariant, first-order, spherical and nonspherical perturbations around an arbitrary spherical spacetime is generalized to higher orders, focusing on second-order perturbation theory. The GS harmonics are generalized to an arbitrary number of indices on the unit sphere and a formula is given for their pro

R. Aloisio, A. Galante, A. F. Grillo, S. Liberati

It was recently proposed that deformations of the relativistic symmetry, as those considered in Deformed Special Relativity (DSR), can be seen as the outcome of a measurement theory in the presence of non-negligible (albeit small) quantum gravitational fluctuations [1,2]. In this paper we explicitly consider the case of a spacetime described by a flat metric

Vladimir Popov

The relativistic kinetic theory of the phonon gas in superfluids is developed. The technique of the derivation of macroscopic balance equations from microscopic equations of motion for individual particles is applied to an ensemble of quasi-particles. The necessary expressions are constructed in terms of a Hamilton function of a (quasi-)particle. A phonon co

Damien Martin

In this thesis three separate problems relevant to general relativity are considered. Methods for algorithmically producing all the solutions of isotropic fluid spheres have been developed over the last five years. A different and somewhat simpler algorithm is discussed here, as well as algorithms for anisotropic fluid spheres. The second and third problems

Jun Chen, Da-ke He, Ashish Jagmohan

We consider Slepian-Wolf code design based on LDPC (low-density parity-check) coset codes for memoryless source-side information pairs. A density evolution formula, equipped with a concentration theorem, is derived for Slepian- Wolf coding based on LDPC coset codes. As a consequence, an intimate connection between Slepian-Wolf coding and channel coding is es

Stephen Luttrell

This paper introduces an objective function that seeks to minimise the average total number of bits required to encode the joint state of all of the layers of a Markov source. This type of encoder may be applied to the problem of optimising the bottom-up (recognition model) and top-down (generative model) connections in a multilayer neural network, and it un

Fabrice Portier, Jean-Yves Baudais, Jean-François Hélard, the Projet europeen IST-MATRICE Collaboration

The paper deals with orthogonal space-time block coded MC-CDMA systems in outdoor realistic downlink scenarios with up to two transmit and receive antennas. Assuming no channel state information at the transmitter, we compare several linear single-user detection and spreading schemes, with or without channel coding, achieving a spectral efficiency of 1-2 bit

Andreas Laeuchli, Guido Schmid, Simon Trebst

We present an extensive numerical study of spin quadrupolar correlations in single and coupled bilinear-biquadratic spin one chains, using several methods such as Exact Diagonalization, Density Matrix Renormalization Group and strong coupling series expansions. For the single chain we clarify the dominant correlation function in the enigmatic gapless period-

Michael Köhl, Anton Öttl, Stephan Ritter, Tobias Donner

We report on the experimental investigation of two-particle correlations between neutral atoms in a Hanbury Brown and Twiss experiment. Both an atom laser beam and a pseudo-thermal atomic beam are extracted from a Bose-Einstein condensate and the atom flux is measured with a single atom counter. We determine the conditional and the unconditional detection pr

T. Campey, C. J. Vale, M. J. Davis, S. Kraft

We analyse photoionisation and ion detection as a means of accurately counting ultra-cold atoms. We show that it is possible to count clouds containing many thousands of atoms with accuracies better than $N^{-1/2}$ with current technology. This allows the direct probing of sub-Poissonian number statistics of atomic samples. The scheme can also be used for ef

Sadhan K. Adhikari

Employing a time-dependent mean-field-hydrodynamic model we study the generation of black solitons in a degenerate fermion-fermion mixture in a cigar-shaped geometry using variational and numerical solutions. The black soliton is found to be the first stationary vibrational excitation of the system and is considered to be a nonlinear continuation of the vibr

Gassem M. Alzoubi Norman O. Birge

We have measured the phase decoherence rate, $τ_ϕ^{-1}$ of conduction electrons in disordered Ag wires implanted with 2 and 10 parts per million Fe impurities, by means of the weak localization magnetoresistance. The Kondo temperature of Fe in Ag, $T_K \approx 4$ K, is in the ideal temperature range to study the progressive screening of the Fe spins as the t

T. Sato, T. Ishiyama, T. Nikuni

We study vortex lattice structures of a trapped Bose-Einstein condensate in a rotating lattice potential by numerically solving the time-dependent Gross-Pitaevskii equation. By rotating the lattice potential, we observe the transition from the Abrikosov vortex lattice to the pinned lattice. We investigate the transition of the vortex lattice structure by cha

Peter Fulde, Peter Thalmeier, Gertrud Zwicknagl

We review theoretical concepts and models for materials with strongly correlated d- or f electrons. We discuss low-energy effective models and the renormalized band method for Ce-based Kondo lattice systems. They are applied to the analysis of associated magnetic and superconducting instabilities. In addititon quantum phase transitions are investigated. Spec

Pankaj Mishra, Yashwant Singh

We develop a free energy functional for an inhomogeneous system that contains both symmetry conserved and symmetry broken parts of the direct pair correlation function. These correlation functions are found by solving the Ornstein- Zernike equation with the Percus-Yevick closure relation. The method developed here gives the pair correlation functions in the

Z. Vörös, D. W. Snoke, L. Pfeiffer, K. West

We have trapped a gas of long-lifetime, high-mobility excitons in an in-plane harmonic potential. Trapping is an important step toward the goal of a controlled Bose-Einstein condensate of excitons. We show that the repulsive interaction between the excitons plays a dominant role in the behavior of the excitons, in contrast to the weak interactions in atomic

J Torok, T. Unger, J. Kertesz, D. E. Wolf

We introduce a model to describe the wide shear zones observed in modified Couette cell experiments with granular material. The model is a generalization of the recently proposed approach based on a variational principle. The instantaneous shear band is identified with the surface that minimizes the dissipation in a random potential that is biased by the loc

A. Pioda, S. Kicin, D. Brunner, T. Ihn

A quantum point contact (QPC) patterned on a two-dimensional electron gas is investigated with a scanning gate setup operated at a temperature of 300 mK. The conductance of the point contact is recorded while the local potential is modified by scanning the tip. Single electron charging of impurities induced by the local potential is observed as a stepwise co

Jun-ichiro Ohe, Tomi Ohtsuki, Bernhard Kramer

A Hall effect due to spin chirality in mesoscopic systems is predicted. We consider a 4-terminal Hall system including local spins with geometry of a vortex domain wall, where strong spin chirality appears near the center of vortex. The Fermi energy of the conduction electrons is assumed to be comparable to the exchange coupling energy where the adiabatic ap

Sebastien Blaineau, Philippe Jund

We present a study of the structural properties of (x)Na$_2$S-(1-x)GeS$_2$ glasses through DFT-based molecular dynamics simulations, at different sodium concentrations ($0<x<0.5$). We computed the radial pair correlation functions as well as the total and partial structure factors. We also analyzed the evolution of the corner- and edge-sharing intertetrahedr

S. K. Pandey, Ashwani Kumar, S. Khalid, A. V. Pimpale

Room temperature Co K- and La L-edges X-ray absorption studies have been carried out on LaCoO$_3$. Experimental near edge structures have been analysed by theoretical LDA+U density of states (DOS) and multiple scattering (MS) calculations. Use of both MS and DOS calculations yield additional information about hybridization of the states of central atom with

Cz. Jasiukiewicz, T. Paszkiewicz, S. Wolski

Fourth-rank tensors of complete Voigt&#39;s symmetry, that embody the elastic properties of crystalline anisotropic substances, were constructed for all 2D crystal systems. Using them we obtained explicit expressions for inverse of Young&#39;s modulus E, inverse of shear modulus G and Poisson&#39;s ratio, which depend on components of the elastic compliances

R. Khasanov, A. Shengelaya, K. Conder, E. Morenzoni

The oxygen-isotope (^{16}O/^{18}O) effect (OIE) on the in-plane magnetic penetration depth λ_{ab}(0) in optimally-doped YBa_2Cu_3O_{7-δ} and La_{1.85}Sr_{0.15}CuO_4, and in slightly underdoped YBa_2Cu_4O_8 and Y_{0.8}Pr_{0.2}Ba_2Cu_3O_{7-δ} was studied by means of muon-spin rotation. A substantial OIE on λ_{ab}(0) with an OIE exponent β_O=-d\lnλ_{ab}(0)/d\ln

F. Mallet, J. Ericsson, D. Mailly, S. Unlubayir

We present phase coherence time measurements in quasi-one-dimensional Ag wires doped with Fe Kondo impurities of different concentrations $n_s$. Due to the relatively high Kondo temperature $T_{K}\approx 4.3K$ of this system, we are able to explore a temperature range from above $T_{K}$ down to below $0.01 T_{K}$. We show that the magnetic contribution to th

R. S. Islam, J. R. Cooper, J. W. Loram, S. H. Naqib

The effects of planar hole content, p (= x), on the uniform (q = 0) magnetic susceptibility, c(T), of La2-xSrxCu1-yZnyO4 were investigated over a wide range of Sr (x) and Zn (y) contents. A strongly p-dependent Zn-induced magnetic behavior was observed. The apparent Zn-induced magnetic moment is larger in underdoped La2-xSrxCu1-yZnyO4 and it decreases quite

T. Paszkiewicz, S. Wolski

Using bases of fourth rank tensorial bases of complete Voigt&#39;s symmetry elaborated by Walpole we obtained expressions for inverse of Young&#39;s modulus E, inverse of shear modulus G and Poisson&#39;s ratio, which depend on components of the stiffness tensor S, on direction cosines of vectors n of uniaxial load and the vector m of lateral strain with cry

P. Pfeffer, W. Zawadzki

A five-level {\Pp} model of the band structure for GaAs-type semiconductors is used to describe the spin $g^*$-factor and the cyclotron mass $m^*_c$ of conduction electrons in GaAs/Ga$_{1-x}$Al$_x$As quantum wells in an external magnetic field parallel to the growth direction. It is demonstrated that the previous theory of the $g^*$-factor in heterostructure

R. A. Martinez, A. Karma, M. C. Flemings

A model for diffusion-controlled spherical particle growth is presented and solved numerically, showing how, on cooling at sufficient rate from a given fraction solid, growth velocity first increases, and then decreases rapidly when solute fields of adjacent particles overlap. An approximate analytical solution for the spherical particle growth velocity is t

Iwan Jensen, Robert M. Ziff

The amplitude ratio of the susceptibility (or second size-moment) for two-dimensional percolation is calculated by two series methods and also by Monte-Carlo simulation. The first series method is a new approach based upon integrating approximations to the scaling function. The second series method directly uses low- and high-density series expansions of the

M. M. Fogler, S. V. Malinin, T. Nattermann

A long one-dimensional wire with a finite density of strong random impurities is modelled as a chain of weakly coupled quantum dots. At low temperature T and applied voltage V its resistance is limited by &#34;breaks&#34;: randomly occuring clusters of quantum dots with a special length distribution pattern that inhibits the transport. Due to the interplay o

Parsa Bonderson, Kirill Shtengel, J. K. Slingerland

We examine interferometric experiments in systems that exhibit non-Abelian braiding statistics, expressing outcomes in terms of the modular S-matrix. In particular, this result applies to FQH interferometry, and we give a detailed treatment of the Read-Rezayi states, providing explicit predictions for the recently observed nu=12/5 plateau.

Asantha Cooray

The shape of the angular power spectrum of galaxies in the linear regime is defined by the horizon size at the matter-radiation equality. When calibrated by cosmic microwave background measurements, the shape of the clustering spectrum can be used as a standard ruler to estimate angular diameter distance as a function of redshift at which galaxy clustering i

E. I. Vorobyov, Shantanu Basu

We present new numerical simulations in the thin-disk approximation which characterize the burst mode of protostellar accretion. The burst mode begins upon the formation of a centrifugally balanced disk around a newly formed protostar. It is comprised of prolonged quiescent periods of low accretion rate (typically $\la 10^{-7} \Msun$ yr$^{-1}$) which are pun

M. C. Medina, M. Gomez Berisso, I. Allekotte, A. Etchegoyen

The Pierre Auger Observatory has been designed to study the highest-energy cosmic rays in nature (E > 10^{18.5} eV). The determination of their arrival direction, energy and composition is performed by the analysis of the atmospheric showers they produce. The Auger Surface Array will consist of 1600 water Cerenkov detectors placed in an equilateral triangula

D. R. Flower, G. Pineau des Forets, C. M. Walmsley

We have studied the chemistry of nitrogen--bearing species during the initial stages of protostellar collapse, with a view to explaining the observed longevity of N2H+ and NH3 and the high levels of deuteration of these species. We followed the chemical evolution of a medium comprising gas and dust as it underwent free--fall gravitational collapse. Chemical

J. S. Sanders, A. C. Fabian

We perform a detailed spatially-resolved, spectroscopic, analysis of the core of the Centaurus cluster of galaxies using a deep Chandra X-ray observation and XMM-Newton data. The Centaurus cluster core has particularly high metallicity, upto twice Solar values, and we measure the abundances of Fe, O, Ne, Mg, Si, S, Ar, Ca and Ni. We map the distribution of t

A. C. Boley, A. C. Mejia, R. H. Durisen, K. Cai

This paper presents a fully three-dimensional radiative hydrodymanics simulation with realistic opacities for a gravitationally unstable 0.07 Msun disk around a 0.5 Msun star. We address the following aspects of disk evolution: the strength of gravitational instabilities under realistic cooling, mass transport in the disk that arises from GIs, comparisons be

C. Ferrari, R. W. Hunstead, L. Feretti, S. Maurogordato

We present the analysis of our 13 and 22 cm ATCA observations of the central region of the merging galaxy cluster A3921 (z=0.094). We investigated the effects of the major merger between two sub-clusters on the star formation (SF) and radio emission properties of the confirmed cluster members. The origin of SF and the nature of radio emission in cluster gala

A. C. Schroeder, G. A. Mamon, R. C. Kraan-Korteweg, P. A. Woudt

The highly obscured radio-bright galaxy PKS1343-601 (l=309.7, b=+1.8) has been suspected to mark the centre of a hitherto unknown cluster in the Great Attractor region. As such it presents an ideal region for a search of galaxies in the near-infrared (NIR) and an in-depth study of their colours as a function of extinction. A visual search of a ~30 square-deg

S. Puccetti, F. Fiore, V. D&#39;Elia, I. Pillitteri

We have surveyed with XMM-Newton the central ~0.6 deg2 region of the ELAIS-S1 field down to flux limits of ~5.5X10-16 cgs (0.5-2 keV, S band), ~2X10-15 cgs (2-10 keV, H band), and ~4X10-15 cgs (5-10 keV, HH band). We detect a total of 478 sources, 395 and 205 of which detected in the S and H bands respectively. We identified 7 clearly extended sources and es

Payam Davoodi, Francesca Pozzi, Seb Oliver, Mari Polletta

We present the rest-frame optical and infrared colours of a complete sample of 1114 z<0.3 galaxies from the Spitzer Wide-area InfraRed Extragalactic Legacy Survey (SWIRE) and the Sloan Digital Sky Survey (SDSS). We discuss the optical and infrared colours of our sample and analyse in detail the contribution of dusty star-forming galaxies and AGN to optically

M. Dahlem, U. Lisenfeld, J. Rossa

We investigate the relation between the existence and size of radio halos, which are believed to be created by star formation (SF) related energy input into the interstellar medium, and other galaxy properties, most importantly star formation activity and galaxy mass. Based on radio continuum and H-alpha observations of a sample of seven late-type spiral gal

Steen Hannestad, Georg G. Raffelt

We determine the range of neutrino masses and cosmic radiation content allowed by the most recent CMB and large-scale structure data. In contrast to other recent works, we vary these parameters simultaneously and provide likelihood contours in the two-dimensional parameter space of N_eff}, the usual effective number of neutrino species measuring the radiatio