January 2006 arXiv papers — page 17

Qiu-Bo Fan, Shou Zhang

We investigate probabilistic dense coding in non-symmetric Hilbert spaces of the sender's and the receiver's particles. The sender and the receiver share the multipartite non-maximally quantum channel. We also discuss the average information.

Ila R. Fiete, H. Sebastian Seung

We present a method of estimating the gradient of an objective function with respect to the synaptic weights of a spiking neural network. The method works by measuring the fluctuations in the objective function in response to dynamic perturbation of the membrane conductances of the neurons. It is compatible with recurrent networks of conductance-based model

Ronald Jackups,, Jie Liang

$β$-barrel membrane proteins are found in the outer membrane of gram-negative bacteria, mitochondria, and chloroplasts. We have developed probabilistic models to quantify propensities of residues for different spatial locations and for interstrand pairwise contact interactions involving strong H-bonds, side-chain interactions, and weak H-bonds. The propensit

Xiang Li, Jie Liang

This chapter discusses theoretical framework and methods for developing knowledge-based potential functions essential for protein structure prediction, protein-protein interaction, and protein sequence design. We discuss in some details about the Miyazawa-Jernigan contact statistical potential, distance-dependent statistical potentials, as well as geometric

Jesus Gomez-Gardenes, Yamir Moreno, Luis Mario Floria

A simple model of activatory-inhibitory interactions controlling the activity of agents (substrates) through a "saturated response" dynamical rule in a scale-free network is thoroughly studied. After discussing the most remarkable dynamical features of the model, namely fragmentation and multistability, we present a characterization of the temporal (

Nicholas P. Linthorne

Optimum projection angles for achieving maximum horizontal range in throwing and jumping events are considerably less than 45 degrees. This unexpected result arise because an athlete can generate a greater projection velocity at low projection angles than at high angles. The range of a projectile is strongly dependent on projection speed and so the optimum p

Stephen P. Nighswander-Rempel

This article demonstrates that a commonly-made assumption in quantum yield calculations may produce errors of up to 25% in extreme cases and can be corrected by a simple modification to the analysis.

Daniel M. Kaplan

Ionization cooling of a muon beam is a key technique for a Neutrino Factory or Muon Collider. An international collaboration is mounting an experiment to demonstrate muon ionization cooling at the Rutherford Appleton Laboratory. We aim to complete the experiment by 2010.

Daniel M. Zuckerman, Edward Lyman

Because of growing interest in temperature-based sampling methods like replica exchange, this note aims to make some observations and raise some potentially important questions which we have not seen addressed sufficiently in the literature. Mainly, we wish to call attention to limits on the maximum speed-up to be expected from temperature-based methods, and

Leon Danon, Albert Diaz-Guilera, Alex Arenas

Identifying community structure can be a potent tool in the analysis and understanding of the structure of complex networks. Up to now, methods for evaluating the performance of identification algorithms use ad-hoc networks with communities of equal size. We show that inhomogeneities in community sizes can and do affect the performance of algorithms consider

S. Burger, R. Köhle, L. Zschiedrich, W. Gao

An extremely fast time-harmonic finite element solver developed for the transmission analysis of photonic crystals was applied to mask simulation problems. The applicability was proven by examining a set of typical problems and by a benchmarking against two established methods (FDTD and a differential method) and an analytical example. The new finite element

R. Barille, S. Dabos-Seignon, J. -M. Nunzi, S. Ahmadi Kandjani

Nonlocal communication between two laser light beams is experimented in a photochromic polymer thin films. Information exchange between the beams is mediated by the self-induction of a surface relief pattern. The exchanged information is related to the pitch and orientation of the grating. Both are determined by the incident beam. The process can be applied

Eric Lewin Altschuler, Antonio Perez-Garrido, Richard Stong

Inspired by, and using methods of optimization derived from classical three dimensional electrostatics, we note a novel beautiful symmetric four dimensional polytope we have found with 80 vertices. We also describe how the method used to find this symmetric polytope, and related methods can potentially be used to find good examples for the kissing and packin

Reginald D. Smith

The social network formed by the collaboration between rappers is studied using standard statistical techniques for analyzing complex networks. In addition, the community structure of the rap music community is analyzed using a new method that uses weighted edges to determine which connections are most important and revealing among all the communities. The r

Jesus Gomez-Gardenes, Pablo Echenique, Yamir Moreno

Most communication networks are complex. In this paper, we address one of the fundamental problems we are facing nowadays, namely, how we can efficiently protect these networks. To this end, we study an immunization strategy and found that it works as good as targeted immunization, but using only local information about the network topology. Our findings are

E. Padilla-Rodal, O. Castanos, R. Bijker, A. Galindo-Uribarri

The low-energy spectra, electric quadrupole transitions and moments for the germanium isotopes are studied in the formalism of the IBM-2 with configuration mixing. The calculated observables reproduce well the available experimental information, including the newly obtained data for radioactive neutron-rich 78, 80, 82 Ge isotopes. A geometric interpretation

W. F. Mueller, M. P. Carpenter, J. A. Church, D. C. Dinca

$B(E3; 0_1^+ \to 3_1^-)$ transition matrix elements have been measured for even-mass $^{124-134}$Xe nuclei using sub-barrier Coulomb excitation in inverse kinematics. The trends in energy $E(3^-)$ and $B(E3; 0_1^+ \to 3_1^-)$ excitation strengths are well reproduced using phenomenological models based on a strong coupling picture with a soft quadrupole mode

Rachid Nouicer

Charged particles produced in Cu+Cu collisions at \sqrt{s_{NN}} = 200 and 62.4 GeV have been measured in the PHOBOS experiment at RHIC. The comparison of the results for Cu+Cu and Au+Au for the most central collisions at the same energy reveals that the particle density per nucleon participant pair and the extended longitudinal scaling behavior are similar i

Romain Bachelard, Cristel Chandre, Xavier Leoncini

A method to reduce or enhance chaos in Hamiltonian flows with two degrees of freedom is discussed. This method is based on finding a suitable perturbation of the system such that the stability of a set of periodic orbits changes (local bifurcations). Depending on the values of the residues, reflecting their linear stability properties, a set of invariant tor

Felipe Barra, Thomas Gilbert, Mauricio Romo

We study the dynamics of classical particles in different classes of spatially extended self-similar systems, consisting of (i) a self-similar Lorentz billiard channel, (ii) a self-similar graph, and (iii) a master equation. In all three systems the particles typically drift at constant velocity and spread ballistically. These transport properties are analyz

Nicolae C. Panoiu, Richard M. Osgood, Boris A. Malomed

We demonstrate that an array of discrete waveguides on a slab substrate, both featuring the $χ^{2}$ nonlinearity, supports stable solitons composed of discrete and continuous components. Two classes of fundamental composite solitons are identified: ones consisting of a discrete fundamental-frequency (FF) component in the waveguide array, coupled to a continu

Anatoliy Klimyk, Jiri Patera

In the paper, properties of orbit functions are reviewed and further developed. Orbit functions on the Euclidean space $E_n$ are symmetrized exponential functions. The symmetrization is fulfilled by a Weyl group corresponding to a Coxeter-Dynkin diagram. Properties of such functions will be described. An orbit function is the contribution to an irreducible c

Timor Saffary

The purpose of this paper is to shed more light on the transition from the known massless modular action to the wanted massive one in the case of forward light cones and double cones. The infinitesimal generator of the massive modular automorphism group is investigated, in particular, some assumptions on its structure are verified explicitly for two concrete

Ricardo A. Mosna

Although it is well known that the Seiberg-Witten equations do not admit nontrivial $L^2$ solutions in flat space, singular solutions to them have been previously exhibited -- either in $R^3$ or in the dimensionally reduced spaces $R^2$ and $R^1$ -- which have physical interest. In this work, we employ an extension of the Hopf fibration to obtain an iterativ

Roberto Fernandez, Juerg Froehlich, Daniel Ueltschi

We use mathematically rigorous perturbation theory to study the transition between the Mott insulator and the conjectured Bose-Einstein condensate in a hard-core Bose-Hubbard model. The critical line is established to lowest order in the tunneling amplitude.

Petko Nikolov, Tihomir Valchev

We give an algorithm to write down all conformally invariant differential operators acting between scalar functions on Minkowski space. All operators of order k are nonlinear and are functions on a finite family of functionally independent invariant operators of order up to k. The independent differential operators of second order are three and we give an ex

Thomas Lam, Mark Shimozono

David Little developed a combinatorial algorithm to study the Schur-positivity of Stanley symmetric functions and the Lascoux-Schützenberger tree. We generalize this algorithm to affine Stanley symmetric functions.

Mihaela Neamtu, Raul Florin Horhat, Dumitru Opris

In this paper we analyze a simple mathematical model which describes the interaction between the proteins p53 and Mdm2. For the stationary state we discuss the local stability and the existence of the Hopf bifurcation. Choosing the delay as a bifurcation parameter we study the direction and stability of the bifurcating periodic solutions. Some numerical exam

Pengzi Miao

Motivated by problems on apparent horizons in general relativity, we prove the following theorem on minimal surfaces: Let $g$ be a metric on the three-sphere $S^3$ satisfying $Ric(g) \geq 2 g$. If the volume of $(S^3, g)$ is no less than one half of the volume of the standard unit sphere, then there are no closed minimal surfaces in the asymptotically flat m

Jan O. Kleppe

The purpose of this paper is to study families of Artinian or one dimensional quotients of a polynomial ring $R$ with a special look to level algebras. Let $\GradAlg^H(R)$ be the scheme parametrizing graded quotients of $R$ with Hilbert function $H$. Let $B \to A$ be any graded surjection of quotients of $R$ with Hilbert function $H_B$ and $H_A$, and h-vecto

Camil Muscalu

We prove L^p estimates for a tri-linear operator, whose symbol is given by the product of two standard symbols, satisfying the well known Marcinkiewicz-Hormander-Mihlin condition. Our main result contains in particular the classical Coifman-Meyer theorem. This tri-linear operator is the simplest example of a large class of multi-linear operators, which we ca

Vitaly Bergelson, Michal Misiurewicz, Samuel Senti

We consider actions of the free semigroup with two generators on the real line, where the generators act as affine maps, one contracting and one expanding, with distinct fixed points. Then every orbit is dense in a half-line, which leads to the question whether it is, in some sense, uniformly distributed. We present answers to this question for various inter

Ben L. Cox, Thomas J. Enright

In this article we study the structure of highest weight modules for quantum groups defined over a commutative ring with particular emphasis on the structure theory for invariant bilinear forms on these modules.

Ben L. Cox, Vyacheslav Futorny

We show that our construction of boson type realizations of affine $\mathfrak{sl}(n+1)$ in terms of intermediate Wakimoto modules gives representations that are generically isomorphic to certain Verma type modules. We then use this identification to obtain information about the submodule structure of intermediate Wakimoto modules

C. Boubel, P. Mounoud, C. Tarquini

We study transversely Lorentzian foliations on the closed 3-manifolds. We classify them under a completeness hypothesis and we deduce the dual classification of codimension 1 geodesically complete timelike totally geodesic foliations. Besides we provide an example of a Lorentzian foliation on a compact 3-manifold which is equicontinuous on a proper dense ope

Sylvie Corteel

We introduce the notion of crossings and nestings of a permutation. We compute the generating function of permutations with a fixed number of weak exceedances, crossings and nestings. We link alignments and permutation patterns to these statistics. We generalize to the case of decorated permutations. Finally we show how this is related to the stationary dist

Jaroslaw Kosiorek, Andrzej Matras

The aim of the paper is to give a synthetic proof that in a symmetric Minkowski plane the Benz's (G) axiom holds (without using the algebraic representation).

David Dos Santos Ferreira, Carlos Kenig, Johannes Sjoestrand, Gunther Uhlmann

In this paper we show, in dimension n >=3, that knowledge of the Cauchy data for the Schroedinger equation in the presence of a magnetic potential, measured on possibly very small subsets of the boundary, determines uniquely the magnetic field and the electric potential.

I. Kopshaev

This paper is devoted to the study of the family of morphisms of vector bundle, defined by the systems equivalence to linear differential equations. It is proved, that the specified families of the morphisms of vector bundle is not saturated.

William D. Banks, Igor E. Shparlinski

We study the function $Θ(x,y,z)$ that counts the number of positive integers $n\le x$ which have a divisor $d>z$ with the property that $p\le y$ for every prime $p$ dividing $d$. We also indicate some cryptographic applications of our results.

L. Berezansky, L. Idels

We introduce a delay nonlinear differential equation model which describes how fish are harvested. In our previous studies we investigated the persistence of that equation and existence of a periodic solution for this equation. Here we study the stability (local and global) of the periodic solutions of that equation.

Jeffrey Morton

Interest in combinatorial interpretations of mathematical entities stems from the convenience of the concrete models they provide. Finding a bijective proof of a seemingly obscure identity can reveal unsuspected significance to it. Finding a combinatorial model for some mathematical entity is a particular instance of the process called ``categorification&#39

Yu. V. Brezhnev

We present some new results in theory of classical theta-functions of Jacobi and sigma-functions of Weierstrass: ordinary differential equations (dynamical systems) and series expansions. The paper is basically organized as a stream of new formulas.

Patrick Boily, Victor G. LeBlanc, Eric T. Matsui

The spiral is one of Nature's more ubiquitous shape: it can be seen in various media, from galactic geometry to cardiac tissue. In the literature, very specific models are used to explain some of the observed incarnations of these dynamic entities. Barkley first noticed that the range of possible spiral behaviour is caused by the Euclidean symmetry that

Axel Hultman

We prove that the weak order on an infinite Coxeter group contains infinite antichains if and only if the group is not affine.

Philippe Gaucher

A flow is homotopy continuous if it is indefinitely divisible up to S-homotopy. The full subcategory of cofibrant homotopy continuous flows has nice features. Not only it is big enough to contain all dihomotopy types, but also a morphism between them is a weak dihomotopy equivalence if and only if it is invertible up to dihomotopy. Thus, the category of cofi

Viviane Baladi, Masato Tsujii

(Revised version, January 2006. S. Gouezel pointed out that, when 1<r<2, the proof in the previous version was incomplete. In fixing this gap, we simplified the argument in Section 6. In addition, there is a new appendix, with an alternative description of the norms. We also corrected a few minor flaws.) We study spectral properties of transfer operators for

Vincent Guedj, Ahmed Zeriahi

We study the complex Monge-Amp\` ere operator on compact Kähler manifolds. We give a complete description of its range on the set of $ω-$plurisubharmonic functions with $L^2$ gradient and finite self energy, generalizing to this compact setting results of U.Cegrell from the local pluripoltential theory. We give some applications to complex dynamics and to th

V. Metaftsis, M. Sykiotis

We show that every virtually torsion-free subgroup of the outer automorphism group of a conjugacy separable hyperbolic group is residually finite. As a result, we are able to prove that the group of outer automorphisms of every finitely generated Fuchsian group and of every free-by-finite group is resudually finite. We also generalize the main result for rel

Stéphane Launois

Let g be a complex simple Lie algebra of type B_2 and q be a non-zero complex number which is not a root of unity. In the classical case, a theorem of Dixmier asserts that the simple factor algebras of the positive part U^+(g) of the enveloping algebra of g, whose Gelfand-Kirillov dimension is equal to 2, are isomorphic to the first Weyl algebra. In order to

A. S. Buch, R. Rimanyi

We prove a positive combinatorial formula for the equivariant class of an orbit closure in the space of representations of an arbitrary quiver of type $A$. Our formula expresses this class as a sum of products of Schubert polynomials indexed by a generalization of the minimal lace diagrams of Knutson, Miller, and Shimozono. The proof is based on the interpol

Giovanni Alessandrini, Luca Rondi

We prove that a sound-soft polyhedral scatterer is uniquely determined by the far-field pattern corresponding to an incident plane wave at one given wavenumber and one given incident direction.

R. N. Baranov, D. V. Bykov, A. A. Slavnov

It is shown that gauge invariance of the operator \int dx tr(A_μ^{2}-\frac{2}{g ξ} x^ν θ_{μν} A^μ) in noncommutative gauge theory does not lead to gauge independence of its vacuum condensate. Generalized Ward identities are obtained for Green&#39;s functions involving operator \underset{Ω\to \infty}{lim}\frac{1}Ω \int\limits_Ω dx tr(A_μ^{2}) in noncommutativ

David S. Berman, Malcolm J. Perry

The partition function of the membrane is investigated. In particular, the case relevant to perturbative string theory of a membrane with topology $S^1 \times Σ$ is examined. The coupling between the string world sheet Euler character and the dilaton is shown to arise from a careful treatment of the membrane partition function measure. This demonstrates that

Gianguido Dall&#39;Agata, Sergio Ferrara

We give a basic review of some recent developments in local supersymmetry breaking in 4-dimensional effective theories coming from compactifications of string and M-theory in the presence of non-trivial form and geometrical fluxes.

Miao Li, Wei Song, Tower Wang

We discuss a few examples in 2+1 dimensions and 1+1 dimensions supporting a recent conjecture concerning the relation between the Planck scale and the coupling strength of a non-gravitional interaction, unlike those examples in 3+1 dimensions, we do not have to resort to exotic physics such as small black holes. However, the result concerning these low dimen

Aba Teleki, Milan Noga

Relations and isomorphisms between quantum field theories in operator and functional integral formalisms are analyzed from the viewpoint of inequivalent representations of commutator or anticommutator rings of field operators. A functional integral in quantum field theory cannot be regarded as a Newton-Lebesgue integral but rather as a formal object to which

Eugen Radu

We consider static, nonabelian solutions in N=4, D=5 Romans&#39; gauged supergravity model. Numerical arguments are presented for the existence of asymptotically anti-de Sitter configurations in the $N=4^+$ version of the theory, with a dilaton potential presenting a stationary point. Considering the version of the theory with a Liouville dilaton potential,

Mohsen Alishahiha, Hossein Yavartanoo

We study singular 1/2 BPS solutions in M-theory using 11-dimensional superstar solutions. The superstar solutions and their corresponding plane wave limits could give an insight how one may deform the boundary conditions to get singular, but still physically acceptable, solutions. Starting from M-theory solutions with an isometry, we will also study 10-dimen

V. V. Skokov, V. D. Toneev

A hybrid model is put forward for describing relativistic heavy ion collisions. The early interaction stage responsible for entropy creation is calculated within the transport Quark-Gluon String Model resulting in an initial state. The passage to subsequent isoentropic expansion proceeds with exact account for all conservation laws. Relativistic 3D hydrodyna

M. Chemtob, P. N. Pandita

We carry out a detailed analysis of the nonminimal supersymmetric standard model with lepton number violation. The model contains a unique trilinear lepton number violating term in the superpotential which can give rise to neutrino masses at the tree level. We search for the gauged discrete symmetries realized by cyclic groups which preserve the structure of

Yu. N. Pokotilovski

Constraints for the constants of hypothetical Yukawa-type corrections to the Newtonian gravitational potential are obtained from analysis of neutron scattering experiments. Restrictions are obtained for the interaction range between 10^{-12} and 10^{-7} cm, where Casimir force experiments and atomic force microscopy are not sensitive. Experimental limits are

T. Hattori, M. Hayashi, T. Inagaki, Y. Kitadono

We study the thermal and curvature effect to spontaneous symmetry breaking in phi^4 theory. The effective potential is evaluated in D-dimensional static universe with positive curvature R X S^{D-1} or negative curvature R X H^{D-1}. It is shown that temperature and positive curvature suppress the symmetry breaking, while negative curvature enhances it. To co

Kazuo Koike

The problem of elementarity of electric charge is investigated. It is known that possible proton decay is caused by $X$ and $Y$ bosons which are characteristic in GUTs. The charge structure of GUTs is, however, not simple, and the five types of charge units appear. We investigate the problem of elementarity in taking into account of the simplest model of the

B. B. Deo, P. K. Mishra

We make a systematic theoretical analysis of the masses and their variation with energy by solving the renormalization group equation (RGE) in the Minimal Supersymmetric Standard Model (MSSM). The unification fermion masses of around 115 GeV at GeV scale has been derived by Deo and Maharana. Here we undertake the unfinished but the important task of calculat

Alicia M. Sintes, Badri Krishnan

We describe an improved version of the Hough transform search for continuous gravitational waves from isolated neutron stars assuming the input to be short segments of Fourier transformed data. The method presented here takes into account possible non-stationarities of the detector noise and the amplitude modulation due to the motion of the detector. These t

R. Balbinot, A. Fabbri, S. Fagnocchi, R. Parentani

Using the action principle we first review how linear density perturbations (sound waves) in an Eulerian fluid obey a relativistic equation: the d&#39;Alembert equation. This analogy between propagation of sound and that of a massless scalar field in a Lorentzian metric also applies to non-homogeneous flows. In these cases, sound waves effectively propagate

David Wands

Brane-world models, where observers are restricted to a brane in a higher-dimensional spacetime, offer a novel perspective on cosmology. I discuss some approaches to cosmology in extra dimensions and some interesting aspects of gravity and cosmology in brane-world models.

Steve Drasco, Scott A. Hughes

Using black hole perturbation theory, we calculate the gravitational waves produced by test particles moving on bound geodesic orbits about rotating black holes. The orbits we consider are generic - simultaneously eccentric and inclined. The waves can be described as having radial, polar, and azimuthal &#34;voices&#34;, each of which can be made to dominate

Riccardo Pucella, Vicky Weissman

ODRL is a popular XML-based language for stating the conditions under which resources can be accessed legitimately. The language is described in English and, as a result, agreements written in ODRL are open to interpretation. To address this problem, we propose a formal semantics for a representative fragment of the language. We use this semantics to determi

Ming-Yang Kao, Manan Sanghi, Robert Schweller

We consider the problem of efficiently designing sets (codes) of equal-length DNA strings (words) that satisfy certain combinatorial constraints. This problem has numerous motivations including DNA computing and DNA self-assembly. Previous work has extended results from coding theory to obtain bounds on code size for new biologically motivated constraints an

Mukunda P. Das, Frederick Green

In the ballistic limit, the Landauer conductance steps of a mesoscopic quantum wire have been explained by coherent and dissipationless transmission of individual electrons across a one-dimensional barrier. This leaves untouched the central issue of conduction: a quantum wire, albeit ballistic, has finite resistance and so must dissipate energy. Exactly HOW

Masa Ishigami, J. H. Chen, E. D. Williams, D. Tobias

The 1/f noise in individual semiconducting carbon nanotubes (s-CNT) in a field effect transistor configuration has been measured in ultra-high vacuum and following exposure to air. The amplitude of the normalized current spectral noise density is independent of source-drain current, indicating the noise is due to mobility rather than number fluctuations. Hoo

Henry C. Fu, Alexander Seidel, John Clarke, Dung-Hai Lee

We present a theory for a finite-length superconducting nanowire coupled to an environment. We show that in the absence of dissipation quantum phase slips always destroy superconductivity, even at zero temperature. Dissipation stabilizes the superconducting phase. We apply this theory to explain the &#34;anti-proximity effect&#34; recently seen by Tian et. a

Henry C. Fu, Dung-Hai Lee

Angle-resolved photoemission data on optimally- and under-doped high temperature superconductors reveal a dichotomy between the nodal and antinodal electronic excitations. In this paper we propose an explanation of this unusual phenomenon by employing the coupling between the quasiparticle and the commensurate/incommensurate magnetic excitations.

Sanjib Sabhapandit, Satya N. Majumdar, Alain Comtet

We present a formalism for obtaining the statistical properties of functionals and inverse functionals of the paths of a particle diffusing in a one-dimensional quenched random potential. We demonstrate the implementation of the formalism in two specific examples: (1) where the functional corresponds to the local time spent by the particle around the origin

Latha Venkataraman, Yeon Suk Hong, Philip Kim

We have measured electron transport in small bundles of identical conducting Molybdenum Selenide nanowires where the number of weakly interacting one-dimensional chains ranges from 1-300. The linear conductance and current in these nanowires exhibit a power-law dependence on temperature and bias voltage respectively. The exponents governing these power laws

Amit K Chattopadhyay

We show that the energy levels predicted by a 1/N-expansion method for an N-dimensional Hydrogen atom in a spherical potential are always lower than the exact energy levels but monotonically converge towards their exact eigenstates for higher ordered corrections. The technique allows a systematic approach for quantum many body problems in a confined potentia

Sorin Bastea

We present molecular dynamics simulations of aggregation kinetics in a colloidal suspension modeled as a highly asymmetric binary mixture. Starting from a configuration with largely uncorrelated colloidal particles the system relaxes by coagulation-fragmentation dynamics to a structured state of low-dimensionality clusters with an exponential size distributi

Xin Chen, NaiJuan Wu, John Strozier, Alex Ignatiev

We report the direct observation of the electric pulse induced resistance-change (EPIR) effect at the nano scale on La1-xSrxMnO3 (LSMO) thin films by the current measurement AFM technique. After a switching voltage of one polarity is applied across the sample by the AFM tip, the conductivity in a local nanometer region around the AFM tip is increased, and af

H. Mukuda, M. Abe, Y. Araki, Y. Kitaoka

We report a site selective Cu-NMR study on under-doped Hg-based five-layered high-$T_{\rm c}$ cuprate HgBa2Ca4Cu5Oy with a Tc=72 K. Antiferromagnetism (AF) has been found to take place at TN=290 K, exhibiting a large antiferromagnetic moment of 0.67-0.69uB at three inner planes (IP&#39;s). This value is comparable to the values reported for non-doped cuprate

Thomas Petermann, Paolo De Los Rios

Supplementing a lattice with long-range connections effectively models small-world networks characterized by a high local and global interconnectedness observed in systems ranging from society to the brain. If the links have a wiring cost associated to their length l, the corresponding distribution q(l) plays a crucial role. Uniform length distributions have

J. Twamley, D. W. Utami, H. -S. Goan, G. J. Milburn

We study the electrical transport of a harmonically-bound, single-molecule endohedral fullerene shuttle operating in the Coulomb blockade regime, i.e. single electron shuttling. In particular we examine the dependance of the tunnel current on an ultra-small stationary force exerted on the shuttle. We derive a quantum master equation for the full shuttle syst

Matej Komelj Daniel Steiauf Manfred Faehnle

The magnetic anisotropy energy of Fe and Co monatomic nanowires both free-standing and at the step edge of a Pt surface is investigated within the framework of the density-functional theory and local-spin-density (LSDA) approximation. Various types of the analysis of the calculated data reveal that the spin-orbit interaction of the Pt atoms and the hybridiza

A. Cabuz, D. Felbacq

In the homogenization of composite metamaterials the role played by the relative positions of the wires and resonators is not well understood, though essential. We present a general argument which shows that the homogenization of such metamaterials can be seen as the homogenization of 1D single negative stacks. The sensitivity to the geometrical parameters i

M. Yu. Kharitonov, A. F. Volkov, K. B. Efetov

We study a change in the spin magnetization of a superconductor-ferromagnet (SF) heterostructure, when temperature is lowered below the superconducting transition temperature. It is assumed that the SF interface is smooth on the atomic scale and the mean free path is not too short. Solving the Eilenberger equation we show that the spin magnetic moment induce

S. Duhot, R. Mélin

We investigate one dimensional models (the Blonder, Tinkham, Klapwijk model and a tight-binding model) of non local transport at normal metal / superconductor (NS) double interfaces. We find a negative elastic cotunneling crossed conductance, strongly enhanced by additional scatterers away from the interfaces, suggesting the possibility of reflectionless tun

C. Faugeras, G. Martinez, F. Capotondi, G. Biasiol

We have investigated the infrared transmission of a two-dimensional (2DEG) electron gas confined in a $Al_{0.25}In_{0.75}As/Ga_{0.25}In_{0.75}As$ single quantum well in order to study the electron optical phonon interaction in a two phonon mode system. Infrared transmission experiments have been performed in both the perpendicular Faraday (PF) and tilted Far

C. Faugeras, D. K. Maude, G. Martinez, L. B. Rigal

We have investigated the magnetophonon resonance (MPR) effect in a series of single GaAs quantum well samples which are symmetrically modulation doped in the adjacent short period AlAs/GaAs superlattices. Two distinct MPR series are observed originating from the $Γ$ and X electrons interacting with the GaAs and AlAs longitudinal optic (LO) phonons respective

A. Bernand-Mantel, P. Seneor, N. Lidgi, M. Munoz

We have fabricated nanometer sized magnetic tunnel junctions using a new nanoindentation technique in order to study the transport properties of a single metallic nanoparticle. Coulomb blockade effects show clear evidence for single electron tunneling through a single 2.5 nm Au cluster. The observed magnetoresistance is the signature of spin conservation dur

C. Faugeras, G. Martinez, A. Riedel, R. Hey

The Frohlich interaction is one of the main electron-phonon intrinsic interactions in polar materials originating from the coupling of one itinerant electron with the macroscopic electric field generated by any longitudinal optical (LO) phonon. Infra-red magneto-absorption measurements of doped GaAs quantum wells structures have been carried out in order to

A. Ruschhaupt, A. del Campo, J. G. Muga

A Bose-Einstein condensate may be prepared in a highly elongated harmonic trap with negligible interatomic interactions using a Feshbach resonance. If a strong repulsive interatomic interaction is switched on and the axial trap is removed to let the condensate evolve freely in the axial direction, a time dependent quantum interference pattern takes place in

T. Gilbert, J. R. Dorfman

We discuss the fluctuation properties of equilibrium chaotic systems with constraints such as iso-kinetic and Nosé-Hoover thermostats. Although the dynamics of these systems does not typically preserve phase-space volumes, the average phase-space contraction rate vanishes, so that the stationary states are smooth. Nevertheless finite-time averages of the pha

Pablo Jarillo-Herrero, Jorden A. van Dam, Leo P. Kouwenhoven

Electronic transport through nanostructures is greatly affected by the presence of superconducting leads. If the interface between the nanostructure and the superconductors is sufficiently transparent, a dissipationless current (supercurrent) can flow through the device due to the Josephson effect. A Josephson coupling, as measured via the zero-resistance su

Sharan Shetty, D. G. Kanhere, Sourav Pal, Anick Goursot

Periodic density functional theory has been employed to characterize the differences in the structural, Lewis acidic and hydrophobic properties of Sn--BEA and Ti--BEA. We show that the incorporation of Sn increases the Lewis acidity of BEA compared to the incorporation of Ti. Hence, the present work gives an insight into the role of Sn in increasing the effi

Osamu Suzuki, Hiroyuki S. Suzuki, Hideaki Kitazawa, Giyuu Kido

We performed ultrasonic measurement on the rare-earth intermetallic compound PrInAg_2 to examine the quadrupolar Kondo effect associated with the non-Kramers Gamma_3 doublet ground state. The characteristic softening of the elastic constant (c_{11}-c_{12})/2 below 10 K in PrInAg_2 is attributed to a Curie term in quadrupolar susceptibility for the quadrupole

R. F. Wang, C. Nisoli, R. S. Freitas, J. Li

We report an artificial geometrically frustrated magnet based on an array of lithographically fabricated single-domain ferromagnetic islands. The islands are arranged such that the dipole interactions create a two-dimensional analogue to spin ice. Images of the magnetic moments of individual elements in this correlated system allow us to study the local acco

T. Motohashi, B. Raveau, M. Hervieu, A. Maignan

The magnetic and magnetotransport properties of the Sr3Fe2-xCoxO7-d system (0.2 <= x <= 1.0) were systematically investigated. This oxide system exhibits a giant magnetoresistance (GMR) effect at low temperatures, reaching up to 80% in 7 T at 5 K. Ac-susceptibility measurements show that there exists a strong competition between ferromagnetic (F) and spin gl

H. Kitatani, A. Aoki

The nature of the probability distribution function of the local energy in the $\pm J$ Ising model has been investigated. At finite temperature, it has been derived that the probability distribution function must satisfy several relations at $p=1/2$ ($p$ is the concentrationof the ferromagnetic bond) and at Nishimori-line, respectively on any lattice in any

Changbong Hyeon, D. Thirumalai

Loop formation between monomers in the interior of semiflexible chains describes elementary events in biomolecular folding and DNA bending. We calculate analytically the interior distance distribution function for semiflexible chains using a mean-field approach. Using the potential of mean force derived from the distance distribution function we present a si