January 2007 arXiv papers — page 9

Kyo Nishiyama

We study the null fiber of a moment map related to dual pairs. We construct an equivariant resolution of singularities of the null fiber, and get conormal bundles of closed $ K_C $-orbits in the Lagrangian Grassmannian as the categorical quotient. The conormal bundles thus obtained turn out to be a resolution of singularities of the closure of nilpotent $ K_

Kyo Nishiyama

We consider two linear reductive algebraic groups $ G $ and $ G' $ over $ C $. Take a finite dimensional rational representation $ W $ of $ G \times G' $. Let $ Y = W // G := Spec C[W]^G $ and $ X = W // G' := \Spec C[W]^{G'} $ be the affine quotients. The quotient space $ X $ (respectively $ Y $) naturally inherits the action of $ G $ (respe

Michael Botros Shenouda, T. N. Davidson

We consider joint transceiver design for general Multiple-Input Multiple-Output communication systems that implement interference (pre-)subtraction, such as those based on Decision Feedback Equalization (DFE) or Tomlinson-Harashima precoding (THP). We develop a unified framework for joint transceiver design by considering design criteria that are expressed a

Bendong Lou

In this note, we propose Bernstein's problem and De Giorgi's conjecture for spatially inhomogeneous equations, as well as De Giorgi's conjecture for system of reaction-diffusion equations.

Juan Martin Mombelli

We establish a bijective correspondence between gauge equivalence classes of dynamical twists in a finite-dimensional Hopf algebra $H$ based on a finite abelian group $A$ and equivalence classes of pairs $(K, \{V_λ\}_{λ\in \hat{A}})$, where $K$ is an $H$-simple left $H$-comodule semisimple algebra and $\{V_λ\}_{λ\in \hat{A}}$ is a family of irreducible repre

T. B. Pittman, B. C. Jacobs, J. D. Franson

We report on an experimental investigation of a single-photon source based on a quantum interference effect first demonstrated by Koashi, Matsuoka, and Hirano [Phys. Rev. A 53, 3621 (1996)]. For certain types of measurement-based quantum information processing applications this technique may be useful as a high rate, but random, source of single photons.

Samuel A. Kutin, David Petrie Moulton, Lawren M. Smithline

We consider a model of computation motivated by possible limitations on quantum computers. We have a linear array of n wires, and we may perform operations only on pairs of adjacent wires. Our goal is to build a circuits that perform specified operations spanning all n wires. We show that the natural lower bound of n-1 on circuit depth is nearly tight for a

Daowen Qiu

{\it Two-way finite automata with quantum and classical states} (2qcfa's) were introduced by Ambainis and Watrous. Though this computing model is more restricted than the usual {\it two-way quantum finite automata} (2qfa's) first proposed by Kondacs and Watrous, it is still more powerful than the classical counterpart. In this note, we focus on deali

Sebastián Risau-Gusman, Guillermo Abramson

We analyze general two-species stochastic models, of the kind generally used for the study of population dynamics. We show that the conditions for the stochastic (microscopic) model to display approximate sustained oscillatory behavior are governed by the parameters of the corresponding deterministic (macroscopic) model. We provide a quantitative criterion f

Robert Rovetti, Kunal K. Das, Alan Garfinkel, Yohannes Shiferaw

Calcium (Ca) plays an important role in regulating various cellular processes. In a variety of cell types, Ca signaling occurs within microdomains where channels deliver localized pulses of Ca which activate a nearby collection of Ca-sensitive receptors. The small number of channels involved ensures that the signaling process is stochastic. The aggregate res

H. Soula, C. C. Chow

We present a simple Markov model of spiking neural dynamics that can be analytically solved to characterize the stochastic dynamics of a finite-size spiking neural network. We give closed-form estimates for the equilibrium distribution, mean rate, variance and autocorrelation function of the network activity. The model is applicable to any network where the

I. Z. Shkurchenko

These examples are absent in the text of "Mechanics of liquids and gas, or mechanics of the inertless mass", as it was said in "Foreword of the editor" (Part I of this monograph). The editor places the missing text separately since some theoretical and practical positions, including most examples, were developed by the author himself in two h

Pedro Chaves De Souza Segundo, Ismahène Hamdi, Michèle Fichet, Daniel Bloch

We report on the analysis of FM selective reflection experiments on the 6S1/2->8P3/2 transition of Cs at 388 nm, and on the measurement of the surface van der Waals interaction exerted by a sapphire interface on Cs(8P3/2). Various improvements in the systematic fitting of the experiments have permitted to supersede the major difficulty of a severe overlap of

Byoung Hee Hong, Kyoung Eun Lee, Jae Woo Lee

We consider the scaling behaviors for fluctuations of the number of Korean firms bankrupted in the period from August 1 2002 to October 28 2003. We observe a power law for the distribution of the number of the bankrupted firms. The Pareto exponent is close to unity. We also consider the daily increments of the number of firms bankrupted. The probability dist

Ralf Rapp

Electromagnetic probes promise to be direct messengers of (spectral properties of) hot and dense matter formed in heavy-ion collisions, even at soft momentum transfers essential for characterizing possible phase transitions. We examine how far we have progressed toward this goal by highlighting recent developments, and trying to establish connections between

N. Paar, D. Vretenar, E. Khan, G. Colo

We review recent studies of the evolution of collective excitations in atomic nuclei far from the valley of $β$-stability. Collective degrees of freedom govern essential aspects of nuclear structure, and for several decades the study of collective modes such as rotations and vibrations has played a vital role in our understanding of complex properties of nuc

H. Oeschler, J. Cleymans, K. Redlich, S. Wheaton

The recently discovered sharp peak in the excitation function of the K+/pi+ ratio around 30 A GeV in relativistic heavy-ion collisions is discussed in the framework of the Statistical Model. In this model, the freeze-out of an ideal hadron gas changes from a situation where baryons dominate to one with mainly mesons. This transition occurs at a temperature T

Tapan K. Nayak

The ALICE experiment has several unique features which makes it an important contributor to proton-proton physics at the LHC, in addition to its specific design goal of studying the physics of strongly interacting matter in heavy-ion collisions. The unique capabilities include its low transverse momentum (\pT) acceptance, excellent vertexing, particle identi

David Verney, C. Bourgeois, C. Donzaud, S. Essabaa

Excited levels were attributed to $^{81}_{31}$Ga$_{50}$ for the first time which were fed in the $β$-decay of its mother nucleus $^{81}$Zn produced in the fission of $^{nat}$U using the ISOL technique. We show that the structure of this nucleus is consistent with that of the less exotic proton-deficient N=50 isotones within the assumption of strong proton Z=

A. Huke, K. Czerski, P. Heide

The investigation of the d+d fusion reactions in metallic environments at sub-Coulomb energies demands especially adapted techniques beyond standard procedures in nuclear physics. The measurements which were performed with an electrostatic accelerator at different self-implanted metallic target materials show an enhancement of the reaction cross-section comp

Gabor I. Veres

New results on antiparticle to particle ratios in Cu+Cu and Au+Au collisions at sqrt(s_NN) = 62.4 and 200 GeV from the PHOBOS experiment at RHIC are presented. Transverse momentum spectra of pions, kaons, protons and antiprotons from Au+Au collisions at sqrt(s_NN) = 62.4 GeV close to mid-rapidity are also discussed. Antiparticle to particle ratios are found

T. Kolokolnikov, M. J. Ward, J. Wei

Certain two-component reaction-diffusion systems on a finite interval are known to possess mesa (box-like) steadystate patterns in the singularly perturbed limit of small diffusivity for one of the two solution components. As the diffusivity D of the second component is decreased below some critical value Dc, with Dc = O(1), the existence of a steady-state m

Aristophanes Dimakis, Folkert Muller-Hoissen

In case of the KP hierarchy where the dependent variable takes values in an (arbitrary) associative algebra A, it is known that there are solutions which can be expressed in terms of quasideterminants of a Wronski matrix which solves the linear heat hierarchy. We obtain these solutions without the help of quasideterminants in a simple way via solutions of ma

Ian Marquette

We consider a superintegrable Hamiltonian system in a two-dimensional space with a scalar potential that allows one quadratic and one cubic integral of motion. We construct the most general associative cubic algebra and we present specific realizations. We use them to calculate the energy spectrum. All classical and quantum superintegrable potentials separab

Tepper L Gill, Woodford W. Zachary

A well-known unsolved problem (in the classical theory of fluid mechanics) is to identify a set of initial velocities, which may depend on the viscosity, the body forces and possibly the boundary of the fluid that will allow global in time solutions to the three-dimensional Navier-Stokes equations. (These equations describe the time evolution of the fluid ve

A. Guionnet, D. Shlyakhtenko

We study solutions to the free stochastic differential equation $dX_t = dS_t - \half DV(X_t)dt$, where $V$ is a locally convex polynomial potential in $m$ non-commuting variables. We show that for self-adjoint $V$, the law $μ_V$ of a stationary solution is the limit law of a random matrix model, in which an $m$-tuple of self-adjoint matrices are chosen accor

Luca Barbieri-Viale, Bruno Kahn

Let X be an n-dimensional smooth proper variety over a field admitting resolution of singularities, and Y,Z two disjoint closed subsets of X. We establish an isomorphism M(X-Z,Y) isomorphic to M(X-Y,Z)^*(n)[2n] in Voevodsky's triangulated category of geometric motives. Here, M(X-Z,Y) is the motive of X -Z relative to its closed subset Y.

Ahmad El Soufi, Said Ilias

In this paper, we investigate critical points of the Laplacian's eigenvalues considered as functionals on the space of Riemmannian metrics or a conformal class of metrics on a compact manifold. We obtain necessary and sufficient conditions for a metric to be a critical point of such a functional. We derive specific consequences concerning possible locall

Amanda Folsom

We provide an exact formula for the complex exponents in the modular product expansion of the modular units, and deduce a characterization of the modular units in terms of the growth of these exponents, answering a question of W. Kohnen.

Yi Zhou, Zhen Lei

In this paper we prove the global existence and uniqueness of the low regularity solutions to the Cauchy problem of quasi-linear wave equations with radial symmetric initial data in three space dimensions. The results are based on the end-point Strichartz estimate together with the characteristic method.

Ahmad El Soufi, Mustapha Jazar, Régis Monneau

In this paper we study a simple non-local semilinear parabolic equation with Neumann boundary condition. We give local existence result and prove global existence for small initial data. A natural non increasing in time energy is associated to this equation. We prove that the solution blows up at finite time $T$ if and only if its energy is negative at some

Ahmad El Soufi, Hector Giacomini, Mustapha Jazar

We prove the following conjecture recently formulated by Jakobson, Nadirashvili and Polterovich \cite{JNP}: on the Klein bottle $\mathbb{K}$, the metric of revolution $$g_0= {9+ (1+8\cos ^2v)^2\over 1+8\cos ^2v} (du^2 + {dv^2\over 1+8\cos ^2v}),$$ $0\le u <\fracπ2$, $0\le v <π$, is the \emph{unique} extremal metric of the first eigenvalue of the Laplacian vi

Andrea Ferretti, Umberto Zannier

Let k be a number field. It is well known that the set of sequences composed by Taylor coefficients of rational functions over k is closed under component-wise operations, and so it can be equipped with a ring structure. A conjecture due to Pisot asks if (after enlarging the field) one can take d-th roots in this ring, provided d-th roots of coefficients can

Luis A. Caffarelli, Ulisse Stefanelli

We address the self-similar solvability of a singular parabolic problem and show that solutions to parabolic fully nonlinear equations are not expected to be $C^{2,1}$.

Ezra Getzler

Operads may be represented as symmetric monoidal functors on a small symmetric monoidal category. We discuss the axioms which must be imposed on a symmetric monoidal functor in order that it give rise to a theory similar to the theory of operads: we call such functors patterns. We also develop the enriched version of the theory, and show how it may be applie

Hongbo Li

In symbolic computing, a major bottleneck is middle expression swell. Symbolic geometric computing based on invariant algebras can alleviate this difficulty. For example, the size of projective geometric computing based on bracket algebra can often be restrained to two terms, using final polynomials, area method, Cayley expansion, etc. This is the &#34;binom

Yingcun Xia

In this paper, we propose two new methods to estimate the dimension-reduction directions of the central subspace (CS) by constructing a regression model such that the directions are all captured in the regression mean. Compared with the inverse regression estimation methods (e.g. Li, 1991, 1992; Cook and Weisberg, 1991), the new methods require no strong ass

Johan Ernest Mebius

The general 4D rotation matrix is specialised to the general 3D rotation matrix by equating its leftmost top element (a00) to 1. Its associate matrix of products of the left-hand and right-hand quaternion components is specialised correspondingly. Inequalities involving the angles through which the coordinate axes in 3D space are displaced are used to prove

Petrus H. R. dos Anjos, Paulo A. Faria da Veiga

We obtain the low-lying energy-momentum spectrum for the imaginary-time lattice four-Fermi or Gross-Neveu model in $d+1$ space-time dimensions ($d=1,2,3$) and with $N$-component fermions. Let $κ>0$ be the hopping parameter, $λ>0$ the four-fermion coupling and $M>0$ denote the fermion mass; and take $s\times s$ spin matrices, $s=2,4$. We work in the $κ\ll 1$

R. D&#39;Auria, S. Ferrara, M. Trigiante

We derive the complete supergravity description of the N=2 scalar potential which realizes a generic flux-compactification on a Calabi-Yau manifold (generalized geometry). The effective potential V_{eff}=V_{(\partial_Z V=0)}$, obtained by integrating out the massive axionic fields of the special quaternionic manifold, is manifestly mirror symmetric, i.e. inv

Riccardo Apreda, Johanna Erdmenger, Dieter Lust, Christoph Sieg

We motivate and summarize our analysis of hep-th/0610276 in which we consider D7-brane probe embeddings in the Polchinski-Strassler background with N=2 supersymmetry. The corresponding dual gauge theory is given by the N=2* theory with fundamental matter.

M. R. Setare

In the present paper we consider the interacting holographic model of dark energy to investigate the validity of the generalized second laws of thermodynamics in non-flat (closed) universe enclosed by the event horizon measured from the sphere of the horizon named $L$. We show that for $L$ as the system&#39;s IR cut-off the generalized second law is respecte

Kazuya Koyama, Andrew Mennim, V. A. Rubakov, David Wands

In this paper we quantise scalar perturbations in a Randall-Sundrum-type model of inflation where the inflaton field is confined to a single brane embedded in five-dimensional anti-de Sitter space-time. In the high energy regime, small-scale inflaton fluctuations are strongly coupled to metric perturbations in the bulk and gravitational back-reaction has a d

J. L. Diaz-Cruz, John Ellis, Keith A. Olive, Yudi Santoso

We analyze the possibility that the lighter stop {\tilde t_1} could be the next-to-lightest supersymmetric particle (NLSP) in models where the gravitino is the lightest supersymmetric particle (LSP). We do not find any possibility for a stop NLSP in the constrained MSSM with universal input soft supersymmetry-breaking masses at the GUT scale (CMSSM), but do

A. V. Kuznetsov, N. V. Mikheev

The fermion spin-flip conversion f_L -> f_R + gamma is considered, caused by the difference of the additional energies of the electroweak origin, acquired by left- and right-handed fermions (neutrino, electron) in medium. An accurate taking account of the fermion and photon dispersion in medium is performed. It is shown that the threshold arises in the proce

E. Santopinto, R. Bijker

We present the formalism for a new generation of unquenched quark models in which quark-antiquark pair effects are taken into account in an explicit form via a microscopic QCD-inspired quark-antiquark creation mechanism. No truncation in the sum over all the big tower of states is necessary since these states are automatically generated by means of powerful

V. A. Okorokov, S. B. Nurushev

Motivated by the present extensive RHIC (BNL) spin program and further PAX project at FAIR, we study the possibility of explicit reconstruction of full set of helicity amplitudes by joint consideration of elastic proton-proton and proton-antiproton scattering. Procedure is based on the derivative relations for the helicity amplitudes, explicit parametrizatio

Francois Gelis

At large collision energy sqrt(s) and relatively low momentum transfer Q, one expects a new regime of Quantum Chromo-Dynamics (QCD) known as &#34;saturation&#34;. This kinematical range is characterized by a very large occupation number for gluons inside hadrons and nuclei; this is the region where higher twist contributions are as large as the leading twist

S. Ceci, A. Svarc, B. Zauner

For last two decades different quark models have predicted diverse, sometimes contradictory collections of resonant states. To choose the best among them, the obtained sets had to be compared to available experimental values. In the absence of a more thorough understanding, quark-model resonant states have been directly identified with scattering-matrix sing

M. Cristoforetti, P. Faccioli, M. Traini

We use the Interacting Instanton Liquid Model (IILM) as a tool to study the role played by the chiral interactions in the lowest-lying vector and axial vector meson resonances. We find that narrow a1 and rho meson resonances can be generated by instanton-induced chiral forces, even in the absence of confinement. In the IILM, these hadrons are found to have m

Jae Sik Lee, Stefano Scopel

We discuss the lower bound to the lightest Higgs boson H_1 in the minimal supersymmetric extension of the standard model (MSSM) with explicit CP violation, and the phenomenology of the lightest relic neutralino in the same scenario. In particular, adopting the CPX benchmark scenario, we find that the combination of experimental constraints coming from LEP, T

Brian J. Rebel

The results from the initial exposure of the MINOS detectors to neutrinos produced by the Fermilab NuMI beam are reported here. The exposure consisted of 1.27 x 10^{20} 120 GeV protons incident on the NuMI target. The data show the observation of 215 neutrinos with energies below 30 GeV while 336 +/- 14.4 events were expected. The data are consistent with nu

Kieran Boyle

A major goal of the RHIC spin program is to measure Δg, the gluon contribution to the proton&#39;s spin. Measurements by PHENIX of the double longitudinal spin asymmetry, A_LL, of the neutral pion production at mid-rapidity in polarized proton collisions have been shown to constrain Δg. Results from the 2005 RHIC run, as well as high p_T data from the 2006 R

Emanuele Di Marco

We present recent results on CP violation, and the determination of CKM angle beta, with the decay B0->K+K-K0, with BABAR and Belle detectors.

Matthew D. Duez, Yuk Tung Liu, Stuart L. Shapiro, Masaru Shibata

The merger of two neutron stars usually produces a remnant with a mass significantly above the single (nonrotating) neutron star maximum mass. In some cases, the remnant will be stabilized against collapse by rapid, differential rotation. MHD-driven angular momentum transport eventually leads to the collapse of the remnant&#39;s core, resulting in a black ho

Sandro G. Fernandes, Geusa de A. Marques, V. B. Bezerra

We obtain solutions of the Klein-Gordon and Dirac equations in the gravitational fields of vacuumless defects. We calculate the energy levels and the current, respectively, in the scalar and spinor cases. In all these situations we emphasize the role played by the defects on the solutions, energy and current.

Martin Bojowald

Quantum gravity places entirely new challenges on the formulation of a consistent theory as well as on an extraction of potentially observable effects. Quantum corrections due to the gravitational field are commonly expected to be tiny because of the smallness of the Planck length. However, a consistent formulation now shows that key features of quantum grav

Giampiero Sindoni, Claudio Paris, Paolo Ialongo

We show here that the recent claim of a test of the Lense-Thirring effect with an error of 0.5% using the Mars Global Surveyor is misleading and the quoted error is incorrect by a factor of at least ten thousand. Indeed, the simple error analysis of [1] neglects the role of some important systematic errors affecting the out-of-plane acceleration. The prelimi

Alain Frisch, Haruo Hosoya

Macro tree transducers (mtt) are an important model that both covers many useful XML transformations and allows decidable exact typechecking. This paper reports our first step toward an implementation of mtt typechecker that has a practical efficiency. Our approach is to represent an input type obtained from a backward inference as an alternating tree automa

Th. Hadzilacos, D. Kalles, M. Pouliopoulou

The Hellenic Open University has embarked on a large-scale effort to enhance its textbook-based material with content that demonstrably supports the basic tenets of distance learning. The challenge is to set up a framework that allows for the production-level creation, distribution and consumption of content, and at the same time, evaluate the effort in term

Vik Singh, Jim Gray, Ani Thakar, Alexander S. Szalay

The SkyServer is an Internet portal to the Sloan Digital Sky Survey Catalog Archive Server. From 2001 to 2006, there were a million visitors in 3 million sessions generating 170 million Web hits, 16 million ad-hoc SQL queries, and 62 million page views. The site currently averages 35 thousand visitors and 400 thousand sessions per month. The Web and SQL logs

Jim Gray, Alex Szalay, Tamas Budavari, Robert Lupton

Cross-match spatially clusters and organizes several astronomical point-source measurements from one or more surveys. Ideally, each object would be found in each survey. Unfortunately, the observation conditions and the objects themselves change continually. Even some stationary objects are missing in some observations; sometimes objects have a variable ligh

Jim Gray, Maria A. Nieto-Santisteban, Alexander S. Szalay

Zones index an N-dimensional Euclidian or metric space to efficiently support points-near-a-point queries either within a dataset or between two datasets. The approach uses relational algebra and the B-Tree mechanism found in almost all relational database systems. Hence, the Zones Algorithm gives a portable-relational implementation of points-near-point, sp

Katalin Szlavecz, Andreas Terzis, Stuart Ozer, Razvan Musaloiu-E

Wireless sensor networks can revolutionize soil ecology by providing measurements at temporal and spatial granularities previously impossible. This paper presents a soil monitoring system we developed and deployed at an urban forest in Baltimore as a first step towards realizing this vision. Motes in this network measure and save soil moisture and temperatur

Russell Sears, Catharine Van Ingen, Jim Gray

Application designers often face the question of whether to store large objects in a filesystem or in a database. Often this decision is made for application design simplicity. Sometimes, performance measurements are also used. This paper looks at the question of fragmentation - one of the operational issues that can affect the performance and/or manageabili

Maria A. Nieto-Santisteban, Aniruddha R. Thakar, Alexander S. Szalay, Jim Gray

Current and future astronomical surveys are producing catalogs with millions and billions of objects. On-line access to such big datasets for data mining and cross-correlation is usually as highly desired as unfeasible. Providing these capabilities is becoming critical for the Virtual Observatory framework. In this paper we present various performance tests

Jim Gray, Catharine van Ingen

The SATA advertised bit error rate of one error in 10 terabytes is frightening. We moved 2 PB through low-cost hardware and saw five disk read error events, several controller failures, and many system reboots caused by security patches. We conclude that SATA uncorrectable read errors are not yet a dominant system-fault source - they happen, but are rare com

Gordon Bell, Jim Gray, Alex Szalay

Computational science is changing to be data intensive. Super-Computers must be balanced systems; not just CPU farms but also petascale IO and networking arrays. Anyone building CyberInfrastructure should allocate resources to support a balanced Tier-1 through Tier-3 design.

Alexander S. Szalay, Jim Gray, George Fekete, Peter Z. Kunszt

We describe a method to subdivide the surface of a sphere into spherical triangles of similar, but not identical, shapes and sizes. The Hierarchical Triangular Mesh (HTM) is a quad-tree that is particularly good at supporting searches at different resolutions, from arc seconds to hemispheres. The subdivision scheme is universal, providing the basis for addre

Jim Gray, Alex Szalay, Gyorgy Fekete

This article explains how to add spatial search functions (point-near-point and point in polygon) to Microsoft SQL Server 2005 using C# and table-valued functions. It is possible to use this library to add spatial search to your application without writing any special code. The library implements the public-domain C# Hierarchical Triangular Mesh (HTM) algori

Manoj V. Athawale, Gaurav Goel, Tuhin Ghosh, Thomas M. Truskett

We present results from extensive molecular dynamics simulations of collapse transitions of hydrophobic polymers in explicit water focused on understanding effects of lengthscale of the hydrophobic surface and of attractive interactions on folding. Hydrophobic polymers display parabolic, protein-like, temperature-dependent free energy of unfolding. Folded st

L. Zeng, E. Helgren, F. Hellman, R. Islam

The magnetic rare earth element gadolinium (Gd) was doped into thin films of amorphous carbon (hydrogenated \textit{a}-C:H, or hydrogen-free \textit{a}-C) using magnetron co-sputtering. The Gd acted as a magnetic as well as an electrical dopant, resulting in an enormous negative magnetoresistance below a temperature ($T&#39;$). Hydrogen was introduced to con

I. Polyanski, A. G. Andreev, V. Krastev, M. Mladenova

We consider the optical conductivity of carriers scattered by local sombrero potentials associated with hindered planar rotators in solids. Examples for hindered rotators are provided by off-center substitutional Li ions in colored alkali halides and off-site apical oxygens O(A) in layered perovskites. We obtain off-center displacements by solving for the vi

P. M. Sousa, S. A. Dias, A. J. Silvestre, O. Conde

We report on the synthesis of highly oriented a-axis CrO2 films onto (0001) sapphire by atmospheric pressure CVD from CrO3 precursor, at growth temperatures down to 330 degree Celsius, i.e. close to 70 degrees lower than in published data for the same chemical system. The films keep the high quality magnetic behaviour as those deposited at higher temperature

S. Y. Li, Louis Taillefer, G. Wu, X. H. Chen

The in-plane thermal conductivity $κ$ of the layered superconductor Cu$_x$TiSe$_2$ was measured down to temperatures as low as $T_c$/40, at $x$ = 0.06 near where the CDW order vanishes. The absence of a residual linear term at $ T \to 0$ is strong evidence for conventional s-wave superconductivity in this system. This is further supported by the slow magneti

J. R. Cooper

The results of a computer analysis of a simple 2D quantum mechanical tunnelling model are reported. These suggest that the spatial dependence of the superconducting energy gap observed by Scanning Tunnelling Spectroscopy (STS) studies of single crystals of the high Tc superconductor Bi:2212 is not necessarily caused by nanoscale inhomogeneity. Instead the sp

M. Tasinkevych, S. Dietrich

For one-component volatile fluids governed by dispersion forces an effective interface Hamiltonian, derived from a microscopic density functional theory, is used to study complete wetting of geometrically structured substrates. Also the long range of substrate potentials is explicitly taken into account. Four types of geometrical patterns are considered: (i)

Jean-Francois Berret, Regis Cartier

During the past years we have investigated the complexation between nanocolloids and oppositely charged polymers. The nanocolloids examined were ionic surfactant micelles and inorganic oxide nanoparticles. For the polymers, we used homopolyelectrolytes and block copolymers with linear and comb architectures. In general, the attractive interactions between op

J. -F. Berret

We report on the electrostatic complexation between oppositely charged polymers and inorganic nanoparticles investigated by static and dynamical light scattering. The nanoparticles put under scrutiny were citrate-coated nanocrystals of cerium oxide (CeO2, nanoceria), of iron oxide (Fe2O3, maghemite) and of europium-doped yttrium vanadate (Eu:YVO4) with sizes

Hiroyuki Yamase, Walter Metzner

We analyze a mean-field model of electrons on a square lattice with two types of interaction: forward scattering favoring a d-wave Pomeranchuk instability and a BCS pairing interaction driving d-wave superconductivity. Tuning the interaction parameters a rich variety of phase diagrams is obtained. If the BCS interaction is not too strong, Fermi surface symme

Federico Becca, Luca Capriotti, Alberto Parola, Sandro Sorella

We show strong numerical evidence in favor of an unexpected virtually gapless spectrum, with edge states localized at the boundaries, in frustrated spin-1/2 antiferromagnetic ladders with an odd number of legs. These features can be accurately reproduced by using a projected BCS wave function with a non-trivial pairing, that mixes even and odd reflection sym

S. Ihnatsenka, I. V. Zozoulenko

The origin of the 0.7-conductance anomaly in quantum point contacts (QPCs) has been a subject of lively discussions since its discovery more than 10 years ago. In a recent letter, based on spin density functional theory (DFT), Rejec and Meir explained the origin of the 0.7-anomaly as being due to the formation of a magnetic impurity in the QPCs [T. Rejec and

Dvira Segal, David R. Reichman

We investigate the quantum Zeno and anti-Zeno effects in spin bath models: the spin-boson model and a spin-fermion model. We show that the Zeno-anti-Zeno transition is critically controlled by the system-bath coupling parameter, the same parameter that determines spin decoherence rate. We also discuss the crossover in a biased system, at high temperatures, a

I. Pavlyukevich

We solve a problem of non-convex stochastic optimisation with help of simulated annealing of Levy flights of a variable stability index. The search of the ground state of an unknown potential is non-local due to big jumps of the Levy flights process. The convergence to the ground state is fast due to a polynomial decrease rate of the temperature.

M. Pereiro, D. Baldomir, S. V. Man&#39;kovsky, K. Warda

The ab initio full-potential linearized augmented plane-wave method explicitly designed for the slab geometry was employed to elucidate the physical origin of the layer potentials for the trilayers nFe/3Cr/nFe(001), where n is the number of Fe monolayers. The thickness of the transition-metal ferromagnet has been ranged from $n=1$ up to n=8 while the spacer

I. Pavlyukevich

Let L(t) be a Levy flights process with a stability index α\in(0,2), and U be an external multi-well potential. A jump-diffusion Z satisfying a stochastic differential equation dZ(t)=-U&#39;(Z(t-))dt+σ(t)dL(t) describes an evolution of a Levy particle of an `instant temperature&#39; σ(t) in an external force field. The temperature is supposed to decrease pol

C. V. Colin, B. Salameh, C. R. Pasquier, K. Bechgaard

Due to the competition of two anion orders, (TMTSF)2ReO4, presents a phase coexistence between semiconducting and metallic (superconducting) regions (filaments or droplets) in a wide range of pressure. In this regime, the superconducting upper critical field for H parallel to both c* and b&#39; axes present a linear part at low fields followed by a divergenc

Adriana Moreo, D. J. Scalapino

Experiments on polarized fermion gases performed by trapping ultracold atoms in optical lattices, allow the study of an attractive Hubbard model for which the strength of the on site interaction is tuned by means of a Feshbach resonance. Using a well-known particle-hole transformation we discuss how results obtained for this system can be reinterpreted in th

G. Seth Roberts, Tiffany A. Wood, William J. Frith, Paul Bartlett

We demonstrate a novel technique for the measurement of the charge carried by a colloidal particle. The technique uses the phenomenon of the resonance of a particle held in an optical tweezers trap and driven by a sinusoidal electric field. The trapped particle forms a strongly damped harmonic oscillator whose fluctuations are a function of $γ$, the ratio of

A. Sarkar, P. Mukherjee, P. Barat

The diffraction peaks of Zircaloy-2 and Zr-2.5%Nb alloys at various deformations are found to be asymmetric in nature. In order to characterize the microstructure from these asymmetric peaks of these deformed alloys, X-Ray Diffraction Line Profile Analysis like Williamson-Hall technique, Variance method based on second and fourth order restricted moments and

A. Sarkar, P. Mukherjee, P. Barat

Zirconium based alloys have been irradiated with 11 and 15 MeV proton and 116 MeV oxygen ions at different doses. The changes in the microstructure have been studied for the ion irradiated alloys as a function of dose using X-Ray Diffraction Line Profile Analysis (XRDLPA) based on the whole powder pattern fitting technique. It was observed that the microstru

C. Iniotakis, N. Hayashi, Y. Sawa, T. Yokoyama

The tunneling characteristics of planar junctions between a normal metal and a non-centrosymmetric superconductor like CePt3Si are examined. It is shown that the superconducting phase with mixed parity can give rise to characteristic zero-bias anomalies in certain junction directions. The origin of these zero-bias anomalies are Andreev bound states at the in

Andreas Rüegg, Sebastian Pilgram, Manfred Sigrist

We present aspects of strong electron correlation in a model of a BI/M/BI heterostructure where BI is a band insulator and M can be tuned from a metal to a Mott insulator by varying the on-site repulsion. An effective one-dimensional Schroedinger equation for the low-energy part is derived in the framework of the Kotliar-Ruckenstein slave-boson mean-field th

Thorsten Emig

We explore the non-linear dynamics of two parallel periodically patterned metal surfaces that are coupled by the zero-point fluctuations of the electromagnetic field between them. The resulting Casimir force generates for asymmetric patterns with a time-periodically driven surface-to-surface distance a ratchet effect, allowing for directed lateral motion of

Eric Sultan, Arezki Boudaoud

Gels are used to design bilayered structures with high residual stresses. The swelling of a thin layer on a compliant substrate leads to compressive stresses. The post-buckling of this layer is investigated experimentally; the wavelengths and amplitudes of the resulting modes are measured. A simplified model with a self-avoiding rod on a Winkler foundation i

Didier Mayou, Guy Trambly De Laissardière

The semi-classical Bloch-Boltzmann theory is at the heart of our understanding of conduction in solids, ranging from metals to semi-conductors. Physical systems that are beyond the range of applicability of this theory are thus of fundamental interest. This is the case of disordered systems which present quantum interferences in the diffusive regime, i.e. An

Ying-Jer Kao, Hae-Young Kee

We study effects of Fermi surface fluctuations on a single-particle life time near the diagonal electronic nematic phase on a two-dimensional square lattice. It has been shown that there exists a quantum critical point (QCP) between the diagonal nematic and isotropic phases. We study the longitudinal fluctuations of the order parameter near the critical poin

Na Sai, Neil Bushong, Ryan Hatcher, Massimiliano Di Ventra

So far transport properties of nanoscale contacts have been mostly studied within the static scattering approach. The electron dynamics and the transient behavior of current flow, however, remain poorly understood. We present a numerical study of microscopic current flow dynamics in nanoscale quantum point contacts. We employ an approach that combines a micr

P. Zaleski-Ejgierd, P. Pyykkö, M. Hakala

The cyanides $M$CN, $M$=Cu, Ag, Au, have experimentally a structure with hexagonally packed, infinite -$M$-CN-$M$-CN- chains. Following our earlier study for AuCN, we now predict that all three $M$CN could have an alternative $M_3$C$_3$N$_3$ sheet structure of comparable energy with the known one. The valence isoelectronic systems $M$C$_2$ versus $M_3$C$_6$,

M. S. Cunha

This paper reviews some of the important advances made over the last decade concerning theory of roAp stars.