February 2007 arXiv papers — page 4

M. Gersborg-Hansen, S. Balslev, N. A. Mortensen, A. Kristensen

We have investigated the bleaching dynamics that occur in optofluidic dye lasers where the liquid laser dye in a microfluidic channel is locally bleached due to optical pumping. We find that for microfluidic devices, the dye bleaching may be compensated through diffusion of dye molecules alone. By relying on diffusion rather than convection to generate the n

J. Taruna, J. Piekarewicz, M. A. Perez-Garcia

Quantum simulations of complex fermionic systems suffer from a variety of challenging problems. In an effort to circumvent these challenges, simpler ``semi-classical'' approaches have been used to mimic fermionic correlations through a fictitious ``Pauli potential''. In this contribution we examine two issues. First, we address some of the in

William A. Horowitz

We present the LHC predictions for the WHDG model of radiative, elastic, and path length fluctuating energy loss. We find the pT dependence of RAA is qualitatively very different from AWS-based energy loss extrapolations to the LHC; the large pT reach of the year one data at the LHC should suffice to distinguish between the two. We also discuss the importanc

V. K. Magas, L. P. Csernai, E. Molnar

The freeze out of the expanding systems, created in relativistic heavy ion collisions, will be discussed. We combine kinetic freeze out equations with Bjorken type system expansion into a unified model. Such a model is a more physical generalization of the earlier simplified non-expanding freeze out models. We shall see that the basic freeze out features, po

Chiho Nonaka

We give a short review of hydrodynamic models at heavy ion collisions from the point of view of initial conditions, an equation of states (EoS) and freezeout process. Then we show our latest results of a combined fully three-dimensional macroscopic/microscopic transport approach. In this model for the early, dense, deconfined stage relativistic 3D-hydrodynam

Pedro R. del Santoro, Raul O. Vallejos, Alfredo M. Ozorio de Almeida

We define a coupling of two baker maps through a pi/2 rotation both in position and in momentum. The classical trajectories thus exhibit spiraling, or loxodromic motion, which is only possible for conservative maps of at least two degrees of freedom. This loxodromic baker map is still hyperbolic, that is, fully chaotic. Quantization of this map follows on si

Yavuz Nutku

By Magri's theorem the bi-Hamiltonian structure of Plebanski's second heavenly equation proves that (anti)-self-dual gravity is a completely integrable system in four dimensions.

D. V. Makarov, M. Yu. Uleysky

Motion of an ensemble of particles in a space-periodic potential well with a weak wave-like perturbation imposed is considered. We found that slow oscillations of wavenumber of the perturbation lead to occurrence of directed particle current. This current is amplifying with time due to giant acceleration of some particles. It is shown that giant acceleration

Peter D. Hislop, Eric Soccorsi

Devices exhibiting the integer quantum Hall effect can be modeled by one-electron Schroedinger operators describing the planar motion of an electron in a perpendicular, constant magnetic field, and under the influence of an electrostatic potential. The electron motion is confined to bounded or unbounded subsets of the plane by confining potential barriers. T

Peter D. Hislop, Eric Soccorsi

Devices exhibiting the integer quantum Hall effect can be modeled by one-electron Schroedinger operators describing the planar motion of an electron in a perpendicular, constant magnetic field, and under the influence of an electrostatic potential. The electron motion is confined to unbounded subsets of the plane by confining potential barriers. The edges of

Joakim Arnlind, Martin Bordemann, Jens Hoppe, Choonkyu Lee

We relate free vector dynamics to the eigenvalue motion of a time-dependent real-symmetric NxN matrix, and give a geodesic interpretation to Ruijsenaars Schneider models.

Francesco Mezzadri

We discuss how to generate random unitary matrices from the classical compact groups U(N), O(N) and USp(N) with probability distributions given by the respective invariant measures. The algorithm is straightforward to implement using standard linear algebra packages. This approach extends to the Dyson circular ensembles too. This article is based on a lectur

G. Sardanashvily

In contrast with differential operators on modules over commutative and graded commutative rings, there is no satisfactory notion of a differential operator in noncommutative geometry.

Dmitry B. Rokhlin

This paper deals with the notion of a large financial market and the concepts of asymptotic arbitrage and strong asymptotic arbitrage (both of the first kind), introduced by Yu.M. Kabanov and D.O. Kramkov. We show that the arbitrage properties of a large market are completely determined by the asymptotic behavior of the sequence of the numéraire portfolios,

Andrea Altomani

Let M be an orbit of a real semisimple Lie group G_0 acting on a complex a flag manifolds G/Q of its complexification G. We study the space of global CR functions on M and characterize those M which are strictly locally CR separable, i.e. those for which global CR functions induce local embeddings in C^n.

J. A. D. Aston

It has been shown that some macroeconomic time series, especially those where outliers could be present, can be well modelled using heavy tailed distributions for the noise components. Methods for deciding when and where heavy-tailed models should be preferred are investigated. These investigations primarily focus on automatic methods for model identificatio

C. S. Jones, J. M. Finn, N. Hengartner

This paper discusses linear regression of strongly correlated data that arises, for example, in magnetohydrodynamic equilibrium reconstructions. We have proved that, generically, the covariance matrix of the estimated regression parameters for fixed sample size goes to zero as the correlations become unity. That is, in this limit the estimated parameters are

Daniel Grau

Capability indices are dimensionless quantities measuring the aptitude of a process to manufacture items whose characteristics must be within a specified tolerance ranges. The usual indices $C_p$, $C_{pk}$, $C_{pm}$, and $C_{pmk}$ are used for a process of normal distribution and a target located at the center of the tolerance interval. Various indices deriv

Javier Aramayona, Hugo Parlier, Kenneth J. Shackleton

Our main theorem identifies a class of totally geodesic subgraphs of the 1-skeleton of the pants complex, each isomorphic to the product of two Farey graphs. We deduce the existence of many convex planes in the 1-skeleton of the pants complex.

Santiago Encinas, Orlando Villamayor

Embedded principalization of ideals in smooth schemes, also known as Log-resolutions of ideals, play a central role in algebraic geometry. If two sheaves of ideals, say $I_1$ and $I_2$, over a smooth scheme $V$ have the same integral closure, it is well known that Log-resolution of one of them induces a Log-resolution of the other. On the other hand, in case

A. E. Frazho, S. ter Horst, M. A. Kaashoek

This paper presents a few additions to commutant lifting theory. An operator interpolation problem is introduced and shown to be equivalent to the relaxed commutant lifting problem. Using this connection a description of all solutions of the former problem is given. Also a new application, involving bounded operators induced by $H^2$ operator-valued function

Marta Casanellas, Jesus Fernandez-Sanchez

The Kimura 3-parameter model on a tree of n leaves is one of the most used in phylogenetics. The affine algebraic variety W associated to it is a toric variety. We study its geometry and we prove that it is isomorphic to a geometric quotient of the affine space by a finite group acting on it. As a consequence, we are able to study the singularities of W and

Yi-Ching Yao

We consider the Gittins index for a normal distribution with unknown mean $θ$ and known variance where $θ$ has a normal prior. In addition to presenting some monotonicity properties of the Gittins index, we derive an approximation to the Gittins index by embedding the (discrete-time) normal setting into the continuous-time Wiener process setting in which the

T. S. T. Wong, W. K. Li

The maximum product of spacings (MPS) is employed in the estimation of the Generalized Extreme Value Distribution (GEV) and the Generalized Pareto Distribution (GPD). Efficient estimators are obtained by the MPS for all $γ$. This outperforms the maximum likelihood method which is only valid for $γ<1$. It is then shown that the MPS gives estimators closer to

Pierre-Emmanuel Chaput

A subvariety of a complex projective space has a well-known dual variety, which is the set of its tangent hyperplanes. The purpose of this paper is to generalise this notion for a subvariety of a quite general partial flag variety. A similar biduality theorem is proved, and the dual varieties of Schubert varieties are described.

Tzuu-Shuh Chiang, Shang-Yuan Shiu, Shuenn-Jyi Sheu

In a market with transaction costs, the price of a derivative can be expressed in terms of (preconsistent) price systems (after Kusuoka (1995)). In this paper, we consider a market with binomial model for stock price and discuss how to generate the price systems. From this, the price formula of a derivative can be reformulated as a stochastic control problem

C. J. Cotter, D. D. Holm, P. E. Hydon

We construct multisymplectic formulations of fluid dynamics using the inverse of the Lagrangian path map. This inverse map -- the ``back-to-labels&#39;&#39; map -- gives the initial Lagrangian label of the fluid particle that currently occupies each Eulerian position. Explicitly enforcing the condition that the fluid particles carry their labels with the flo

Burra G. Sidharth, B S Lakshmi

Two types of population models are well known -- the continuous and the discrete types.The two have very different characteristics and methods of solutions and analysis.In this note, we point out that an iterative technique when applied to the continuous case mimics, surprisingly the discrete theory. The implication is that techniques and conclusions of the

Carme Cascante, Joaquin M. Ortega

We obtain characterizations of positive Borel measures $μ$ on $\B^n$ so that some weighted holomorphic Besov spaces $B_s^p(w)$ are imbedded in $L^p(dμ)$, where $w$ is a $B_p$ weight in the unit ball of $\C^n$.

Eva Trenklerova

Given a compact set K in the plane, which contains no triple of points forming a vertical and a horizontal segment, and a continuous real-valued map f on K, we give a construction of real-valued continuous maps of one variable g,h such that f(x,y)=g(x)+h(y) for all points (x,y) from K. This provides a constructive proof of a part of Sternfeld&#39;s theorem o

Dmitrij Celov, Remigijus Leipus, Anne Philippe

We study the aggregation/disaggregation problem of random parameter AR(1) processes and its relation to the long memory phenomenon. We give a characterization of a subclass of aggregated processes which can be obtained from simpler, &#34;elementary&#34;, cases. In particular cases of the mixture densities, the structure (moving average representation) of the

Louis H. Y. Chen, Aihua Xia

This exposition explains the basic ideas of Stein&#39;s method for Poisson random variable approximation and Poisson process approximation from the point of view of the immigration-death process and Palm theory. The latter approach also enables us to define local dependence of point processes [Chen and Xia (2004)] and use it to study Poisson process approxim

Hock Peng Chan, Cheng-Der Fuh, Inchi Hu

Consider a multi-phase project management problem where the decision maker needs to deal with two issues: (a) how to allocate resources to projects within each phase, and (b) when to enter the next phase, so that the total expected reward is as large as possible. We formulate the problem as a multi-armed bandit problem with precedence relations. In Chan, Fuh

Alessandra Cutri, Nicoletta Tchou

The aim of this article is the explicit construction of some barrier functions (&#34;fundamental solutions&#34;) for the Pucci-Heisenberg operators. Using these functions we obtain the continuity property, up to the boundary, for the viscosity solution of fully non-linear Dirichlet problems on the Heisenberg group, if the boundary of the domain satisfies som

Stefan A. G. De Wannemacker

We present a set of generators of the full annihilator ideal for the Witt ring of an arbitrary field of characteristic unequal to two satisfying a non-vanishing condition on the powers of the fundamental ideal in the torsion part of the Witt ring. This settles a conjecture of Ongenae and Van Geel. This result could only be proved by first obtaining a new low

Ruey S. Tsay

Correlations between asset returns are important in many financial applications. In recent years, multivariate volatility models have been used to describe the time-varying feature of the correlations. However, the curse of dimensionality quickly becomes an issue as the number of correlations is $k(k-1)/2$ for $k$ assets. In this paper, we review some of the

Tze Leung Lai, Samuel Po-Shing Wong

This paper describes a new approach to time series modeling that combines subject-matter knowledge of the system dynamics with statistical techniques in time series analysis and regression. Applications to American option pricing and the Canadian lynx data are given to illustrate this approach.

Cheng Hsiao

We review the advancement of nonstationary time series analysis from the perspective of Cowles Commission structural equation approach. We argue that despite the rich repertoire nonstationary time series analysis provides to analyze how do variables respond dynamically to shocks through the decomposition of a dynamic system into long-run and short-run relati

Hwai-Chung Ho

The Sharpe ratio, which is defined as the ratio of the excess expected return of an investment to its standard deviation, has been widely cited in the financial literature by researchers and practitioners. However, very little attention has been paid to the statistical properties of the estimation of the ratio. Lo (2002) derived the $\sqrt{n}$-normality of t

Volodymyr Mazorchuk, Catharina Stroppel

This paper presents categorifications of (right) cell modules and induced cell modules for Hecke algebras of finite Weyl groups. In type $A$ we show that these categorifications depend only on the isomorphism class of the cell module, not on the cell itself. Our main application is multiplicity formulas for parabolically induced modules over a reductive Lie

Ngai Hang Chan, Chi Tim Ng

This paper develops a European option pricing formula for fractional market models. Although there exist option pricing results for a fractional Black-Scholes model, they are established without accounting for stochastic volatility. In this paper, a fractional version of the Constant Elasticity of Variance (CEV) model is developed. European option pricing fo

J. Q. Adashev, B. A. Omirov, A. Kh. Khudoyberdiyev

In this work nul-filiform and filiform Zinbiel algebras are described up to isomorphism. Moreover, the classification of complex Zinbiel algebras is extended from dimensions $\leq 3$ up to the dimension $4.$

Neil S. Trudnger, Xu-Jia Wang

This note concerns the relationship between conditions on cost functions and domains and the convexity properties of potentials in optimal transportation and the continuity of the associated optimal mappings. In particular, we prove that if the cost function satisfies the condition (A3), introduced in our previous work with Xinan Ma, the densities and their

Sergei Treil

The paper deals with the problem of ideals of $H^\infty$: describe increasing functions $ϕ\ge 0$ such that for all bounded analytic functions $f_1,f_2,...,f_n, τ$ in the unit disc $D$ the condition $|τ(z) | \le ϕ(\sum_k |f_k(z)|)$ for all $z\in D$, implies that $τ$ belong to the ideal generated by $f_1,f_2,...,f_n$. It was proved earlier by the author that t

Marcus Hutter

We introduce a new principle for model selection in regression and classification. Many regression models are controlled by some smoothness or flexibility or complexity parameter c, e.g. the number of neighbors to be averaged over in k nearest neighbor (kNN) regression or the polynomial degree in regression with polynomials. Let f_D^c be the (best) regressor

Seoktae Koh, Robert H. Brandenberger

We compute the spectrum of cosmological perturbations in a scenario in which inflation is driven by radiation in a non-commutative space-time. In this scenario, the non-commutativity of space and time leads to a modified dispersion relation for radiation with two branches, which allows for inflation. The initial conditions for the cosmological fluctuations a

M. Cadoni, R. De Leo, G. Gaeta

We propose a mechanism for fixing the velocity of relativistic soliton based on the breaking of the Lorentz symmetry of the sine-Gordon (SG) model. The proposal is first elaborated for a molecular chain model, as the simple pendulum limit of a double pendulums chain. It is then generalized to a full class of two-dimensional field theories of the sine-Gordon

Stephon Alexander

I propose a reinterpretation of cosmic dark matter in which a rigid network of cosmic strings formed at the end of inflation. The cosmic strings fulfill three functions: At recombination they provide an accretion mechanism for virializing baryonic and warm dark matter into disks. These cosmic strings survive as configurations which thread spiral and elliptic

L. G. Aldrovandi, F. A. Schaposnik

Non-Abelian vortices for a supersymmetric {\cal N}=2 Chern-Simons-Higgs theory are explicitly constructed. We introduce N Higgs fields in the fundamental representation of the U(N) gauge group in order to have a color-flavor SU(N) group remaining unbroken in the asymmetric phase. Bogomol&#39;nyi-like first order equations are found and rotationally symmetric

P. O. Hess, W. Greiner

A scenario is presented on how to shift the predicted cutoff in the cosmic ray spectrum at 10**20 eV, called the Greisen-Zatsepin-Kuzmin limit (GKZ), to larger energies without breaking the Lorentz invariance. The formulation is based on a pseudo-complex extension of standard field theory. The dispersion relation of particles can be changed, leading to a mod

Stanley J. Brodsky, Guy F. de Teramond

The AdS/CFT correspondence between string theory in AdS space and conformal field theories in physical space-time leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. Although QCD is not conformally invariant, one can nevertheless u

G. Calderon, D. Delepine, G. Lopez Castro

Based on the description of unstable $K_{L,S}$ particles in quantum field theory (QFT), we compute the time-dependent probabilities for transitions between asymptotic states in $τ^{\pm} \to [π^+π^-]_Kπ^{\pm}ν$ decays, where the pair $[π^+π^-]_K$ is the product of (intermediate state) neutral kaon decays. Then we propose a definition of $τ$ decays into $K_L$

Alberto Bravo Garcia, Sarira Sahu

We have calculated the 1/M^4 (M the vector boson mass) order correction to the neutrino self-energy in a medium. The possible application of this higher order contribution to the neutrino effective potential is considered in the context of the Early Universe hot plasma and of the cosmological Gamma Ray Burst fireball. We found that, depending on the medium p

M. Tentyukov, J. A. M. Vermaseren

We present TFORM, the version of the symbolic manipulation system FORM that can make simultaneous use of several processors in a shared memory architecture. The implementation uses Posix threads, also called pthreads, and is therefore easily portable between various operating systems. Most existing FORM programs will be able to take advantage of the increase

Jihn E. Kim, Ji-Hun Kim, Bumseok Kyae

We construct a supersymmetric standard model in the context of the $Z_{12-I}$ orbifold compactification of the heterotic string theory. The gauge group is $SU(3)_c\times SU(2)_L\times U(1)_Y\times U(1)^4\times[SO(10)\times U(1)^3]&#39;$. We obtain three chiral families, $3\times\{Q,d^c,u^c,L,e^c,ν^c\}$, and Higgs doublets. There are numerous neutral singlets

Sarira Sahu

The long and short gamma-ray bursts are believed to be produced due to collapse of massive stars and merger of compact binaries respectively. All these objects are rich in neutron and the jet outflow from these objects must have a neutron component in it. By postulating the neutron anti-neutron oscillation in the gamma-ray burst fireball, we show that, 19-38

E. Jennings

The electromagnetic form factors of hadrons as measured both in the space like and time like domains provide fundamental information on the nucleon structure and internal dynamics. General expressions, including the lepton mass, for the spin averaged differential cross section for the annihilation reaction lepton antilepton to proton antiproton are given, as

K. Hamaguchi, T. Hatsuda, M. Kamimura, Y. Kino

If the gravitino mass is in the region from a few GeV to a few 10&#39;s GeV, the scalar lepton X such as stau is most likely the next lightest supersymmetry particle. The negatively charged and long-lived X^- may form a Coulomb bound state (A X) with a nucleus A and may affect the big-bang nucleosynthesis through catalyzed fusion process. We calculate a prod

D. J. Antonio, P. A. Boyle, C. Dawson, T. Izubuchi

We present the latest results from the UKQCD/RBC collaborations for the K_l3 form factor with 2+1 flavours of dynamical domain wall quarks. Simulations are performed on 16^3x32x16 and 24^3x64x16 lattices with three values of the light quark mass, allowing for an extrapolation to the chiral limit. After interpolating to zero momentum transfer, we obtain the p

Yuri V. Stenkin

A new method to study Extensive Air Shower (EAS) hadronic component is proposed. It is shown that addition of specific detectors for thermal neutron detection to a standard array for EAS study can significantly improve its performance. Results of CORSIKA based Monte Carlo simulations as well as preliminary experimental data are presented. A proposal of novel

Manfred Paulini

This paper reviews the spectroscopy and decay of B hadrons at the Tevatron. We discuss the spectroscopy of excited B states (B**, Bs**) and the observation of the Sigma_b baryon at the Tevatron. The second part of this review discusses the decays of B hadrons and measurements of branching fractions. We focus on charmless two-body decays of B->hh.

WA89 Collaboration, M. I. Adamovich, Yu. A. Alexandrov, D. Barberis

We report on the observation of a K$_s$p resonance signal at a mass of 1765$\pm$5 MeV/c$^2$, with intrinsic width $Γ= 108\pm 22$ MeV/c$^2$, produced inclusively in $Σ^-$-nucleus interactions at 340 GeV/c in the hyperon beam experiment WA89 at CERN. The signal was observed in the kinematic region $x_F>0.7$, in this region its production cross section rises ap

I. Dawson, K. Prokofiev

Described in this paper is a new method for determining the non-diffractive part of the inelastic proton-proton cross section, at the LHC centre of mass energy of 14TeV. The method is based on counting the number of inelastic proton-proton interactions in the collision regions. According to preliminary investigation, this measurement will be best suited for

Martin Bojowald

Although there is general agreement that a removal of classical gravitational singularities is not only a crucial conceptual test of any approach to quantum gravity but also a prerequisite for any fundamental theory, the precise criteria for non-singular behavior are often unclear or controversial. Often, only special types of singularities such as the curva

Valerio Faraoni

It has been claimed in several papers that a phantom energy-dominated universe can undergo a ``big trip&#39;&#39;, i.e., tunneling through a wormhole that grows faster than the cosmic substratum due to the accretion of phantom energy, and will reappear on the other mouth of the wormhole. We show that such claims are unfounded and contradict the Einstein equa

J. Mark Heinzle, Claes Uggla, Niklas Rohr

This article is devoted to a study of the asymptotic dynamics of generic solutions of the Einstein vacuum equations toward a generic spacelike singularity. Starting from fundamental assumptions about the nature of generic spacelike singularities we derive in a step-by-step manner the cosmological billiard conjecture: we show that the generic asymptotic dynam

Eitan Bachmat

We survey some results about the asymptotic behavior of discrete spacetime models, which appeared in diverse settings in the physics and math literature. We then discuss some recent applications, including scheduling in disk drives and analysis of airplane boarding strategies.

Fabiano C. Botelho, Rasmus Pagh, Nivio Ziviani

Perfect hash functions can potentially be used to compress data in connection with a variety of data management tasks. Though there has been considerable work on how to construct good perfect hash functions, there is a gap between theory and practice among all previous methods on minimal perfect hashing. On one side, there are good theoretical results withou

Yunxia Chen, Qing Zhao, Ananthram Swami

We address the design of opportunistic spectrum access (OSA) strategies that allow secondary users to independently search for and exploit instantaneous spectrum availability. Integrated in the joint design are three basic components: a spectrum sensor that identifies spectrum opportunities, a sensing strategy that determines which channels in the spectrum t

Matei Ripeanu, Adriana Iamnitchi, Ian Foster, Anne Rogers

Multicast communication primitives have broad utility as building blocks for distributed applications. The challenge is to create and maintain the distributed structures that support these primitives while accounting for volatile end nodes and variable network characteristics. Most solutions proposed to date rely on complex algorithms or global information,

Maurice Margenstern

In this paper, we look at the extention of Hedlund&#39;s characterization of cellular automata to the case of cellular automata in the hyperbolic plane. This requires an additionnal condition. The new theorem is proved with full details in the case of the pentagrid and in the case of the ternary heptagrid and enough indications to show that it holds also on

Lawrence Ong, Mehul Motani

In this paper, we derive the information theoretic capacity of a special class of mesh networks. A mesh network is a heterogeneous wireless network in which the transmission among power limited nodes is assisted by powerful relays, which use the same wireless medium. We investigate the mesh network when there is one source, one destination, and multiple rela

H. J. Mamin, M. Poggio, C. L. Degen, D. Rugar

Magnetic resonance imaging, based on the manipulation and detection of nuclear spins, is a powerful imaging technique that typically operates on the scale of millimeters to microns. Using magnetic resonance force microscopy, we have demonstrated that magnetic resonance imaging of nuclear spins can be extended to a spatial resolution better than 100 nm. The t

F. D. Klironomos, S. -W. Tsai

We study a mixture of fermionic and bosonic cold atoms on a two-dimensional optical lattice, where the fermions are prepared in two hyperfine (isospin) states and the bosons have Bose-Einstein condensed (BEC). The coupling between the fermionic atoms and the bosonic fluctuations of the BEC has similarities with the electron-phonon coupling in crystals. We st

A. M. Prudan, A. V. Mezenov, S. A. Ktitorov

Results of the experimental study of the electromagnetic pumping of frequency 0.3 THz upon the soft mode phonons in the (Ba, Sr)TiO3 film are presented. Some features of the phonon state are revealed using the capacitor thermometer and the thermocouple. The soft mode phonon overheating estimated comparing changes of the planar capacitor capacitance was obser

Frédéric Datchi, Agnès Dewaele, Yann Le Godec, Paul Loubeyre

We report accurate measurements of the equation of state (EOS) of cubic boron nitride by x-ray diffraction up to 160 GPa at 295 K and 80 GPa in the range 500-900 K. Experiments were performed on single-crystals embedded in a quasi-hydrostatic pressure medium (helium or neon). Comparison between the present EOS data at 295 K and literature allows us to critic

S. A. Ktitorov, V. K. Zaitsev, M. I. Fedorov

A quantum limit of the thermoelectric efficiency for heterogeneous media with weak links is established with a use of the Landauer-type formulae.

S. A. Ktitorov

A new approach to the stochastic theory of turbulence is suggested. The coloured noise that is present in the stochastic Navier-Stokes equation is generated from the delta-correlated noise allowing us to avoid the nonlocal field theory as it is the case in the conventional theory. A feed-back mechanism is introduced in order to control the noise intensity.

A. Mughal, M. A. Moore

We study the ground state properties of classical Coulomb charges interacting with a 1/r potential moving on a plane but confined either by a circular hard wall boundary or by a harmonic potential. The charge density in the continuum limit is determined analytically and is non-uniform. Because of the non-uniform density there are both disclinations and dislo

Lucio Isa, Rut Besseling, Wilson C K Poon

We image the flow of a nearly random close packed, hard-sphere colloidal suspension (a `paste&#39;) in a square capillary using confocal microscopy. The flow consists of a `plug&#39; in the center while shear occurs localized adjacent to the channel walls, reminiscent of yield-stress fluid behavior. However, the observed scaling of the velocity profiles with

V. V. Lebedev, K. S. Turitsyn, S. S. Vergeles

We analytically derive an equation describing vesicle evolution in a fluid where some stationary flow is excited regarding that the vesicle shape is close to a sphere. A character of the evolution is governed by two dimensionless parameters, $S$ and $Λ$, depending on the vesicle excess area, viscosity contrast, membrane viscosity, strength of the flow, bendi

A. A. Houck, D. I. Schuster, J. M. Gambetta, J. A. Schreier

Electromagnetic signals in circuits consist of discrete photons, though conventional voltage sources can only generate classical fields with a coherent superposition of many different photon numbers. While these classical signals can control and measure bits in a quantum computer (qubits), single photons can carry quantum information, enabling non-local quan

Vladimir Gritsev, Ehud Altman, Anatoli Polkovnikov, Eugene Demler

Interference experiments with independent condensates provide a powerful tool for analyzing correlation functions. Scaling of the average fringe contrast with the system size is determined by the two-point correlation function and can be used to study the Luttinger liquid liquid behavior in one-dimensional systems and to observe the Kosterlitz-Thouless trans

M. M. Zemljic, P. Prelovsek, T. Tohyama

Spectral functions are evaluated numerically within the t-t&#39;-J model as relevant for electron-doped cuprates. The Fermi surface develops from a pocket-like into a large one with doping. The corresponding pseudogap in the nodal direction is well resolved at low doping and vanishes at intermediate doping. Its presence is strongly temperature dependent and

J. P. Hague

I investigate band and Mott insulating states in a two-band Hubbard model, with the aim of understanding the differences between the idealised one-orbital model and the more realistic multi-band case. Using a projection ansatz I show that additional orbitals suppress the metal-insulator transition, leading to a critical coupling of approximately eight times

Peter Hamm, G. P. Tsironis

Crystalline acetanilide is a an organic solid with peptide bond structure similar to that of proteins. Two states appear in the amide I spectral region having drastically different properties: one is strongly temperature dependent and disappears at high temperatures while the other is stable at all temperatures. Experimental and theoretical work over the pas

Yanxia Xing, Qing-feng Sun, Jian Wang

The response of a quantum dot coupled with one normal lead and a superconductor lead driven by a step-like pulse bias $V_L$ is studied using the non-equilibrium Green function method. In the linear pulse bias regime, the responses of the upwards and downwards bias are symmetric. In this regime the turn-on time and turn-off time are much slower than that of t

Yanxia Xing, Qing-feng Sun, Jian Wang

We study the spin current induced spin-Hall effect that a longitudinal spin dependent chemical potential $qV_{s=x,y,z}$ induces a transverse spin conductances $G^{ss&#39;}$. A four terminal system with Rashba and Dresselhaus spin-orbit interaction (SOI) in the scattering region is considered. By using Landauer-B$\ddot u$ttiker formula with the aid of the Gre

S. Robaszkiewicz, G. Pawlowski

We study two effective models developed for description of superconductors with short-coherence length: (i) the extended Hubbard model with on-site attraction and intersite repulsion, (ii) the model of hard-core charged bosons on a lattice. The analysis is concentrated on the problem of phase separations and competition between superconductivity (SS) and cha

I. E. Chupis

The interaction of light in terahertz frequency region with electromagnons in a sinusoidal incommensurate magnetic state in TbMnO3 is studied. A significant change in the frequency dependence of the dielectric constant e_zz near the temperature of the phase transition from sinusoidal magnetic ordering to spiral spin structure with a spontaneous electric poia

M. V. Chubynsky, M. F. Thorpe

A fast computer algorithm, the pebble game, has been used successfully to study rigidity percolation on 2D elastic networks, as well as on a special class of 3D networks, the bond-bending networks. Application of the pebble game approach to general 3D networks has been hindered by the fact that the underlying mathematical theory is, strictly speaking, invali

M. Bonitz, K. Balzer, R. van Leeuwen

It is proven that the center of mass (COM or Kohn) oscillation of a many-body system in a harmonic trap coincides with the motion of a single particle as long as conserving approximations are applied to treat the interactions. The two conditions formulated by Kadanoff and Baym \cite{kb-book} are shown to be sufficient to preserve the COM mode. The result equ

A. Penzev, Y. Yasuta, M. Kubota

We report on experimental confirmation of the non-classical rotational inertia (NCRI) in solid helium samples originally reported by Kim and Chan. The onset of NCRI was observed at temperatures below ~400 mK. The ac velocity for initiation of the NCRI suppression is estimated to be ~10 $μ$m/sec. After an additional annealing of the sample at $T= 1.8$ K for 1

Takashi Shimada, Fumiko Ogushi, Nobuyasu Ito

The distribution function P(j) of the microscopic energy flux, j, in equilibrium state is studied. It is observed that P(j) has a broad peak in small j regime and a stretched-exponential decay for large j. The peak structure originates in a potential advection term and energy transfer term between the particles. The stretched exponential tail comes from the

Erik Einarsson, Hidetsugu Shiozawa, Christian Kramberger, Mark H. Rummeli

A freestanding film of vertically aligned single-walled carbon nanotubes (VA-SWNTs) synthesized by the alcohol catalytic chemical vapor deposition (ACCVD) method was observed directly by transmission electron microscopy (TEM). These observations revealed that the film is comprised primarily of small SWNT bundles, typically containing 3-8 SWNTs. The lack of s

Lorenzo Malavasi, HyunJeong Kim, Simon J. L. Billinge, Thomas Proffen

La2Mo2O9 (LAMOX) is a fast oxygen ion conductor which shows high oxygen ion conductivities comparable to those of yttria-sabilized zirconia (YSZ) . LAMOX is subject to a structural phase transition from the non-conductive monoclinic form to the highly-conductive cubic form at about 580C. The origin of the conductivity in cubic LAMOX has been suggested to be

Yu-Li Lee, Yu-Wen Lee

We study the low energy properties of the one-orbital quantum double-exchange model by using the slave fermion formulation. We construct a mean-field theory which gives a simple explanation for the magnetic and thermodynamic properties of the ferromagnetic metallic phase in manganites at low energy. The resulting electron spectral function and tunneling dens

Peihong Zhang, Susumu Saito, Steven G. Louie, Marvin L. Cohen

Structures for realizing hole-doped MgB$_2$ without appealing to chemical substitutions are proposed. These structures which consist of alternating MgB$_2$ and graphene layers have small excess energy compared to bulk graphite and MgB$_2$. Density functional theory based first-principles electronic structure calculations show significant charge transfer from

Zhenyu Li, D. S. Kosov

Recent experimental realization [J. Am. Chem. Soc., 127 (2005) 7328] of various dithiocarbamate self assembly on gold surface opens the possibility for use of dithiocarbamate linkers to anchor molecular wires to gold electrodes. In this paper, we explore this hypothesis computationally. We computed the electron transport properties of 4,4&#39;-bipyridine (BP

R. M. Briggs, C. V. Ciobanu

The problem addressed here can be concisely formulated as follows: given a stable surface orientation with a known reconstruction and given a direction in the plane of this surface, find the atomic structure of the steps oriented along that direction. We report a robust and generally applicable variable-number genetic algorithm for step structure determinati