December 2007 arXiv papers — page 8

Shun-ichiro Koh

In liquid helium 4, many features associated to Bose statistics have been masked by the strongly interacting nature of the liquid. As an example of these features, we examine the shear viscosity of liquid helium 4 above the lambda point. Applying the linear-response theory to Poiseuille's formula for the capillary flow, the reciprocal of the shear viscos

Roman Linares, Hugo A. Morales-Tecotl, Omar Pedraza

In looking for imprints of extra dimensions in brane world models one usually builts these so that they are compatible with known low energy physics and thus focuses on high energy effects. Nevertheless, just as submillimeter Newton's law tests probe the mode structure of gravity other low energy tests might apply to matter. As a model example, in this w

Xin-Hui Zhang, Yi-Shi Duan, Yu-Xiao Liu, Li Zhao

Based on the $\phi$-mapping theory, we obtain an exact Bogomol'nyi self-dual equation with a topological term, which is ignored in traditional self-dual equation, in the fractional quantum Hall system. It is revealed that there exist self-dual vortices in the system. We investigate the inner topological structure of the self-dual vortices and show that the t

Yuri A. Serebrennikov

We investigate the hole spin-3/2 relaxation process induced by nonadiabatic stochastic modulations of the instantaneous Luttinger Hamiltonian. The theory allows to consider fluctuations of both the direction and the magnitude of a hole wave vector in all regimes of momentum scattering: from collision-dominated to ballistic.

Samuel Fiorini, Gwenaël Joret

Sewell and Trotter [J. Combin. Theory Ser. B, 1993] proved that every connected alpha-critical graph that is not isomorphic to K_1, K_2 or an odd cycle contains a totally odd K_4-subdivision. Their theorem implies an interesting min-max relation for stable sets in graphs without totally odd K_4-subdivisions. In this note, we give a simpler proof of Sewell an

Jeffrey C. Lagarias

This paper considers solutions (x_1, x_2, ..., x_n) to the cyclic system of n simultaneous congruences r (x_1x_2 ...x_n)/x_i = s (mod |x_i|), for fixed nonzero integers r,s with r>0 and gcd(r,s)=1. It shows this system has a finite number of solutions in positive integers x_i >1 having gcd(x_1x_2...x_n, s)=1, obtaining a sharp upper bound on the maximal size

Yuri Bakhtin

We consider a white noise perturbation of dynamics in the neighborhood of a heteroclinic network. We show that under the logarithmic time rescaling the diffusion converges in distributon in a special topology to a piecewise constant process that jumps between saddle points along the heteroclinic orbits of the network. We also obtain precise asymptotics for t

Eugen J. Ionascu

In this note we characterize all regular tetrahedra whose vertices in R^3 have integer coordinates. The main result is a consequence of the characterization of all equilateral triangles having integer coordinates contained in previous work. Then we use this characterization to point out some corollaries. The number of such tetrahedra whose vertices are in th

Basudeb Dasgupta, Amol Dighe

Neutrinos and antineutrinos emitted from a core collapse supernova interact among themselves, giving rise to collective flavor conversion effects that are significant near the neutrinosphere. We develop a formalism to analyze these collective effects in the complete three-flavor framework. It naturally generalizes the spin-precession analogy to three flavors

E. Minguzzi

The non-imprisonment conditions on spacetimes are studied. It is proved that the non-partial imprisonment property implies the distinction property. Moreover, it is proved that feeble distinction, a property which stays between weak distinction and causality, implies non-total imprisonment. As a result the non-imprisonment conditions can be included in the c

Satadeep Bhattacharjee, Eric Bousquet, Philippe Ghosez

The structural, dielectric and dynamical properties of the low temperature antiferromagnetic orthorhombic phase of CaMnO$_3$ have been computed from first principles using a density functional theory approach within the local spin density approximation. The theoretical structural parameters are in good agreement with experiment. The full set of infrared and

Anzhong Wang, N. O. Santos

Orbifold branes in string theory are investigated, and the general field equations on the branes are given explicitly for type II and heterotic string. It is shown that the effective cosmological constant on each of the two branes can be easily lowered to its current observational value, using large extra dimensions. This is also true for type I string. The

E. Minguzzi

The subject of limit curve theorems in Lorentzian geometry is reviewed. A general limit curve theorem is formulated which includes the case of converging curves with endpoints and the case in which the limit points assigned since the beginning are one, two or at most denumerable. Some applications are considered. It is proved that in chronological spacetimes

Simon DeDeo, Dimitrios Psaltis

Modifications to gravity that add additional functions of the Ricci curvature to the Einstein-Hilbert action -- collectively known as $f(R)$ theories -- have been studied in great detail. When considered as complete theories of gravity they can generate non-perturbative deviations from the general relativistic predictions in the solar system, and the simples

A. G. Akeroyd, Abdesslam Arhrib, Qi-Shu Yan

The charged Higgs boson decays $H^\pm\to W^\pm A_1$ and $H^\pm\to W^\pm h_i$ are studied in the framework of the next-to Minimal Supersymmetric Standard Model (NMSSM). It is found that the decay rate for $H^\pm\to W^\pm A_1$ can exceed the rates for the $τ^\pmν$ and $tb$ channels both below and above the top-bottom threshold. The dominance of $H^\pm\to W^\pm

G. Forst

This submission has been removed because 'G. Forst' is an apparent pseudonym, in violation of arXiv policies.

Fedor Simkovic, Rastislav Dvornicky, Amand Faessler

We present the relativistic calculation of the beta-decay of tritium in a hadron model. The elementary particle treatment of the transition 3H -> 3He + e^- + nu_e is performed in analogy with the description of the beta-decay of neutron. The effects of higher order terms of hadron current and nuclear recoil are taken into account in this formalism. The relat

Debra A. Fischer, Geoffrey W. Marcy, R. Paul Butler, Steven S. Vogt

We report 18 years of Doppler shift measurements of a nearby star, 55 Cancri, that exhibit strong evidence for five orbiting planets. The four previously reported planets are strongly confirmed here. A fifth planet is presented, with an apparent orbital period of 260 days, placing it 0.78 AU from the star in the large empty zone between two other planets. Th

Takahiro Hasebe, Izumi Ojima, Hayato Saigo

In White Noise Analysis (WNA), various random quantities are analyzed as elements of $(S)^{\ast}$, the space of Hida distributions ([1]). Hida distributions are generalized functions of white noise, which is to be naturally viewed as the derivative of the Brownian motion. On $(S)^{\ast}$, the Wick product is defined in terms of the $\mathcal{S}$-transform. W

S. Mahmoudian, A. Langari

The one dimensional anisotropic Kondo-necklace model has been studied by several methods. It is shown that a mean field approach fails to gain the correct phase diagram for the Ising type anisotropy. We then applied the spin wave theory which is justified for the anisotropic case. We have derived the phase diagram between the antiferromagnetic long range ord

Carl M. Bender

For any pair of quantum states, an initial state |I> and a final quantum state |F>, in a Hilbert space, there are many Hamiltonians H under which |I> evolves into |F>. Let us impose the constraint that the difference between the largest and smallest eigenvalues of H, E_max and E_min, is held fixed. We can then determine the Hamiltonian H that satisfies this

Peter Fiebig

We show that Lusztig's conjecture on the irreducible characters of a reductive algebraic group over a field of positive characteristic is equivalent to the generic multiplicity conjecture, which gives a formula for the Jordan-H"older multiplicities of baby Verma modules over the corresponding Lie algebra. Then we give a short overview of a recent pro

Tamás Szabados, Balázs Székely

A new approach to stochastic integration is described, which is based on an a.s. pathwise approximation of the integrator by simple, symmetric random walks. Hopefully, this method is didactically more advantageous, more transparent, and technically less demanding than other existing ones. In a large part of the theory one has a.s. uniform convergence on comp

Thomas P. Branson, Luigi Fontana, Carlo Morpurgo

We derive sharp Moser-Trudinger inequalities on the CR sphere. The first type is in the Adams form, for powers of the sublaplacian and for general spectrally defined operators on the space of CR-pluriharmonic functions. We will then obtain the sharp Beckner-Onofri inequality for CR-pluriharmonic functions on the sphere, and, as a consequence, a sharp logarit

V. S. Fadin, R. Fiore

The dipole (Möbius) representation of the colour singlet BFKL kernel in the next-to-leading order is found in supersymmetric Yang--Mills theories. Ambiguities of this form and its conformal properties are discussed.

R. G. H. Robertson

KATRIN is a very large scale tritium-beta-decay experiment to determine the mass of the neutrino. It is presently under construction at the Forschungszentrum Karlsruhe, and makes use of the Tritium Laboratory built there for the ITER project. The combination of a very large retarding-potential electrostatic-magnetic spectrometer and an intense gaseous molecu

Moses Fayngold

Relativistic kinematics is usually considered only as a manifestation of pseudo-Euclidean (Lorentzian) geometry of space-time. However, as it is explicitly stated in General Relativity, the geometry itself depends on dynamics, specifically, on the energy-momentum tensor. We discuss a few examples, which illustrate the dynamical aspect of the length-contracti

J. Y. Fu, M. Q. Weng, M. W. Wu

We study the spin-orbit coupling in the whole Brillouin zone for GaAs using both the $sp^3s^{\ast}d^5$ and $sp^3s^{\ast}$ nearest-neighbor tight-binding models. In the $Γ$-valley, the spin splitting obtained is in good agreement with experimental data. We then further explicitly present the coefficients of the spin splitting in GaAs $L$ and $X$ valleys. Thes

J. J. Zirbel, K. -K. Ni, S. Ospelkaus, T. L. Nicholson

We report on the creation and characterization of heteronuclear KRb Feshbach molecules in an optical dipole trap. Starting from an ultracold gas mixture of K-40 and Rb-87 atoms, we create as many as 25,000 molecules at 300 nK by rf association. Optimizing the association process, we achieve a conversion efficiency of 25%. We measure the temperature dependenc

Robert R. Tucci

This paper introduces QuanTree v1.1 and QuanLin v1.1, two Java applications available for free. (Source code included in the distribution.) Each application compiles a different type of input quantum evolution operator. The applications output a quantum circuit that is approximately equal to the input evolution operator. QuanTree compiles an input evolution

D. Narbutis, A. Bridzius, R. Stonkute, V. Vansevicius

We study the capability of the UBVRI photometric system to quantify star clusters in terms of age, metallicity, and color excess by their integrated photometry. The well known age-metallicity-extinction degeneracy was analyzed for various parameter combinations, assuming different levels of photometric accuracy. We conclude that the UBVRI photometric system

D. Narbutis, V. Vansevicius, K. Kodaira, A. Bridzius

A study of aperture size effects on star cluster photometry in crowded fields is presented. Tests were performed on a sample of 285 star cluster candidates in the South-West field of the M31 galaxy disk, measured in the Local Group Galaxy Survey mosaic images (Massey et al. 2006). In the majority of cases the derived UBVRI photometry errors represent the acc

I. Sableviciute, V. Vansevicius, K. Kodaira, D. Narbutis

The King and the EFF (Elson, Fall & Freeman 1987) analytical models are employed to determine the structural parameters of star clusters using an 1-D surface brightness profile fitting method. The structural parameters are derived and a catalogue is provided for 51 star cluster candidates from the survey of compact star clusters in the South-West field of th

O. E. Alon, A. I. Streltsov, L. S. Cederbaum

When initially-independent subsystems are made to contact, {\it coherence} can develop due to interaction between them. We exemplify and demonstrate this paradigm through several scenarios of two initially-independent Bose-Einstein condensates which are allowed to collide. The build-up of coherence depends strongly on time, interaction strength and other par

Oleg Ogievetsky, Todor Popov

The ice Ansatz on matrix solutions of the Yang-Baxter equation is weakened to a condition which we call rime. Generic rime solutions of the Yang-Baxter equation are described. We prove that the rime non-unitary (respectively, unitary) R-matrix is equivalent to the Cremmer-Gervais (respectively, boundary Cremmer-Gervais) solution. Generic rime classical r-mat

Huirong Yan, A. Lazarian

Numerical simulations shed light onto earlier not trackable problem of magnetohydrodynamic (MHD) turbulence. They allowed to test the predictions of different models and choose the correct ones. Inevitably, this progress calls for revisions in the picture of cosmic ray (CR) transport. It also shed light on the problems with the present day numerical modeling

David Callan

The title identity appeared as Problem 75-4, proposed by P. Barrucand, in Siam Review in 1975. The published solution equated constant terms in a suitable polynomial identity. Here we give a combinatorial interpretation in terms of card deals.

José P. S. Lemos

Black holes monopolize nowadays the center stage of fundamental physics. Yet, they are poorly understood objects. Notwithstanding, from their generic properties, one can infer important clues to what a fundamental theory, a theory that includes gravitation and quantum mechanics, should give. Here we review the classical properties of black holes and their as

A. M. Badalian, Yu. A. Simonov, M. A. Trusov

The mass shifts of the $P$-wave $D_s$ and $B_s$ mesons due to coupling to $DK$, $D^*K$ and $BK$, $B^*K$ channels are studied using the chiral quark-pion Lagrangian without fitting parameters. The strong mass shifts down $\sim 140$ MeV and $\sim 100$ MeV for $D^*_s(0^+)$ and $D_s(1^{+'})$ and $\sim 100$ MeV for $B^*_s(0^+)$ and $B_s(1^{+'})$ are calcu

Dmitri A. Uzdensky

I propose a new paradigm for solar coronal heating viewed as a self-regulating process keeping the plasma marginally collisionless. The mechanism is based on the coupling between two effects. First, coronal density controls the plasma collisionality and hence the transition between the slow collisional Sweet-Parker and the fast collisionless reconnection reg

Mathieu Colin, David Lannes

We derive various approximations for the solutions of nonlinear hyperbolic systems with fastly oscillating initial data. We first provide error estimates for the so-called slowly varying envelope, full dispersion, and Schrödinger approximations in a Wiener algebra; this functional framework allows us to give precise conditions on the validity of these models

Pieter Thijs Eendebak

In this paper we analyze the tangential symmetries of Darboux integrable decomposable exterior differential systems. The decomposable systems generalize the notion of a hyperbolic exterior differential system and include the classic notion of Darboux integrability for first order systems and second order scalar equations. For Darboux integrable systems the g

Julián Mestre

Lagrangian relaxation has been used extensively in the design of approximation algorithms. This paper studies its strengths and limitations when applied to Partial Cover.

Anar Akhmedov, John B. Etnyre, Thomas E. Mark, Ivan Smith

In this note we construct infinitely many distinct simply connected Stein fillings of a certain infinite family of contact 3--manifolds.

Youngki Yoon, James Fodor, Jing Guo

A vertical partial gate carbon nanotube (CNT) field-effect transistor (FET), which is amenable to the vertical CNT growth process and offers the potential for a parallel CNT array channel, is simulated using a self-consistent atomistic approach. We show that the underlap between the gate and the bottom electrode (required for isolation between electrodes) is

Supriya Jana, Arunava Chakrabarti

We report electronic transmission properties of a tight binding Aharonov-Bohm ring threaded by a magnetic flux, to one arm of which a finite cluster of atoms has been attached from one side. we demonstrate that, by suitably choosing the number of scatterers in each arm of the quantum ring and, by decoupling the ring from the atomic cluster, the transmission

Ivan Osorio, Mark G. Frei, Didier Sornette, John Milton

The concept of universality proposes that dynamical systems with the same power law behaviors are equivalent at large scales. We test this hypothesis on the Earth's crust and the epileptic brain, and discover that power laws also govern the distributions of seizure energies and recurrence times. This robust correspondence is extended over seven statistic

Youngki Yoon, Jing Guo

The effects of edge irregularity and mixed edge shapes on the characteristics of graphene nanoribbon transistors are examined by self-consistent atomistic simulations based on the non-equilibrium Green's function formalism. The minimal leakage current increases due to the localized states induced in the band gap, and the on-current decreases due to small

S. Mendach, S. Kiravittaya, A. Rastelli, M. Benyoucef

We consider a pair of artificial atoms with different ground state energies. By means of finite element calculations we predict that the ground state energies can be tuned into resonance if the artificial atoms are placed into a flexible ring structure, which is elastically deformed by an external force. This concept is experimentally verified by embedding a

Pascal Heus, Richard Gomez

While Quantum Information Science (QIS) is still in its infancy, the ability for quantum based hardware or computers to communicate and integrate with their classical counterparts will be a major requirement towards their success. Little attention however has been paid to this aspect of QIS. To manage and exchange information between systems, today's cla

Elias Bareinboim, Valmir C. Barbosa

The load of a node in a network is the total traffic going through it when every node pair sustains a uniform bidirectional traffic between them on shortest paths. We show that nodal load can be expressed in terms of the more elementary notion of a node's descents in breadth-first-search (BFS or shortest-path) trees, and study both the descent and nodal-

Yunfei Wu, Da-Xin Zhang

We analyze the branching ratio and spectrum for the decay mode $K^+ \toπ^++{\not}E$(missing energy) in the unparticle model, where an unparticle can also serve as the missing energy. A vector unparticle can even mediate the $K^+ \to π^+ +ν\barν$, resulting complicated interference with the Standard Model.

Swarnali Bandopadhyay, Debasish Chaudhuri, Arun M. Jayannavar

We compare two phenomenological models of dephasing that are in use recently. We show that the stochastic absorption model leads to reasonable dephasing in series (double barrier) and parallel (ring) quantum resistors in presence and absence of magnetic flux. For large enough dephasing it leads to Ohm's law. On the other hand a random phase based statist

V. Tarigopula, O. S. Hopperstad, M. Langseth, A. H. Clausen

Tensile tests were conducted on dual-phase high-strength steel in a Split-Hopkinson Tension Bar at a strain-rate in the range of 150-600/s and in a servo-hydraulic testing machine at a strain-rate between 10-3 and 100/s. A novel specimen design was utilized for the Hopkinson bar tests of this sheet material. Digital image correlation was used together with h

Jerry L. Bona, David Lannes, Jean-Claude Saut

We derived here in a systematic way, and for a large class of scaling regimes, asymptotic models for the propagation of internal waves at the interface between two layers of immiscible fluids of different densities, under the rigid lid assumption and with a flat bottom. The full (Euler) model for this situation is reduced to a system of evolution equations p

Vladimir Pascalutsa

I discuss the problem of formulating the baryon chiral perturbation theory ($χ$PT) in the presence of a light resonance, such as the $Δ(1232)$, the lightest nucleon resonance. It is shown how to extend the power counting of $χ$PT to correctly account for the resonant contributions. Recent applications of the resulting chiral effective-field theory to the des

François Hild, Stéphane Roux

A continuous pathway from digital images acquired during a mechanical test to quantitative identification of a constitutive law is presented herein based on displacement field analysis. From images, displacement fields are directly estimated within a finite element framework. From the latter, the application of the equilibrium gap method provides the means f

Andreas Enge

A survey on algorithms for computing discrete logarithms in Jacobians of curves over finite fields.

Jan-Christopher Winter, Frank Krauss

A parton-shower model for hadronic collisions based on the emission properties of QCD dipoles is proposed. This proposal therefore extends the well-known radiation pattern of pure final-state colour dipoles to QCD initial-state radiation, both of which are treated perturbatively. Corresponding dipole splitting functions are derived and the kinematics of all

Shunsuke Yoshimura, Aya Comuta, Noburo Ishii

Enge and Schertz gave the method of using the double eta-quotient for the construction of elliptic curves over finite fields. In their method, it is necessary to count the number of rational points of elliptic curves corresponding to solutions of the modular equation over a finite field, because in advance we can not know which solution of the modular equati

Hirotaka Yoshino

By analyzing the apparent horizon (AH) formation in the collision of two pp-waves with rectangular sources in four dimensions, we study to what extent the AH can be distorted without violating the energy conditions. It is shown that the highly distorted AH can form in this system although it cannot be arbitrarily long. The hoop conjecture is examined for the

L. Dall'Asta, M. Marsili, P. Pin

We discuss the collective behavior of a network of individuals that receive, process and forward to each other tasks. Given costs they store those tasks in buffers, choosing optimally the frequency at which to check and process the buffer. The individual optimizing strategy of each node determines the aggregate behavior of the network. We find that, under ge

V. M. Biryukov

Tabrizi et al. [physics/0701342] discuss the feasibility of an electron-based crystal undulator (e-CU) by planar channeling of 50 GeV electrons through a periodically bent crystal. We show that their scheme is not feasible. First, their undulator parameter is K >> 1 always, which destroys photon interference. Second, they overestimate the electron dechanneli

Garcia de Andrade

Analytical solution of $α$-dynamo equation representing strongly torsioned helical dynamo is obtained in the thin twisted Riemannian flux tubes approximation. The $α$ factor possesses a fundamental contribution from torsion which is however weaken in the thin tubes approximation. It is shown that assuming that the poloidal component of the magnetic field is

Mourad E. H. Ismail, Jiang Zeng

We show connections between a special type of addition formulas and a theorem of Stieltjes and Rogers. We use different techniques to derive the desirable addition formulas. We apply our approach to derive special addition theorems for Bessel functions and confluent hypergeometric functions. We also derive several additions theorems for basic hypergeometric

Jérémie Bourdon, Damien Eveillard, Samuel Gabillard, Theo Merle

Despite recent molecular technique improvements, biological knowledge remains incomplete. Reasoning on living systems hence implies to integrate heterogeneous and partial informations. Although current investigations successfully focus on qualitative behaviors of macromolecular networks, others approaches show partial quantitative informations like protein c

Vincent Laude, Davy Gérard, Naima Khelfaoui, Carlos F. Jerez-Hanckes

We propose and demonstrate experimentally the concept of the annular interdigital transducer that focuses acoustic waves on the surface of a piezoelectric material to a single, diffraction-limited, spot. The shape of the transducing fingers follows the wave surface. Experiments conducted on lithium niobate substrates evidence that the generated surface waves

Probhas Raychaudhuri

The effective photon hypothesis of Panarella and Raychaudhuri shows that the self focusing of photon in the laser beam is inherent and it also shows that the the cause of phenomena of self focusing of intense laser radiation in solids is not actually the nonlinear intensity dependent refractive index. In the effective photon hypothesis the laser photon have

Yu. Dabaghian, A. G. Cohn, L. Frank

We discuss the task of reconstructing the topological map of an environment based on the sequences of locations visited by a mobile agent -- this occurs in systems neuroscience, where one runs into the task of reconstructing the global topological map of the environment based on activation patterns of the place coding cells in hippocampus area of the brain.

Jiangping Wang

This paper proposes new bounds for Marcum Q-function, which prove extremely tight and outperform all the bounds previously proposed in the literature. What is more, the proposed bounds are good and stable both for large values and small values of the parameters of the Marcum Q-function, where the previously introduced bounds are bad and even useless under so

Yeow Meng Chee, Petteri Kaski

Let $Ψ(t,k)$ denote the set of pairs $(v,λ)$ for which there exists a graphical $t$-$(v,k,λ)$ design. Most results on graphical designs have gone to show the finiteness of $Ψ(t,k)$ when $t$ and $k$ satisfy certain conditions. The exact determination of $Ψ(t,k)$ for specified $t$ and $k$ is a hard problem and only $Ψ(2,3)$, $Ψ(2,4)$, $Ψ(3,4)$, $Ψ(4,5)$, and $

Toshiki Nakashima

We obtain the affirmative answer to the conjecture in [15]. More precisely, let X be the affine geometric crystal of type G^(1)_2 in [15] and UD(X,T,θ) a ultra-discretization of X with respect to a certain positive structure θ. Then we show that UD(X,T,θ) is isomorphic to the limit of coherent family of perfect crystals of type D^(3)_4 in [7].

J. Harnad, A. Yu. Orlov

We give a simple algebraic derivation of a useful determinantal identity for multilevel systems such as random matrix chains and finite determinantal point processes, with applications to the calculation of point correlators, gap probabililties and Janossy densities.

Sergey N. Savenkov, Yaroslav V. Aulin

The conditions under which a linear anisotropic polarization element orthogonalizes several polarization states of input totally polarized light were studied in the paper. The criterion for orthogonalization was obtained in the form of inequality for anisotropy parameters. Orthogonalization properties of polarization elements with the most important anisotro

Qayum Khan

Cappell's unitary nilpotent groups UNil(R;R,R) are calculated for the integral group ring R=Z[C_2] of the cyclic group C_2 of order two. Specifically, they are determined as modules over the Verschiebung algebra V using the Connolly--Ranicki isomorphism and the Connolly--Davis relations.

Pengbo Li, Qihuang Gong, Guangcan Guo

We propose a scheme for realizing the Ising spin-spin interaction and atomic cluster states utilizing trapped atoms in coupled microcavities. It is shown that the atoms can interact with each other via the exchange of virtual photons of the cavities. Through suitably tuning the parameters, an effective Ising spin-spin interaction can be generated in this opt

Martin Hairer, Jonathan C. Mattingly

We study the dynamic behavior at high energies of a chain of anharmonic oscillators coupled at its ends to heat baths at possibly different temperatures. In our setup, each oscillator is subject to a homogeneous anharmonic pinning potential $V_1(q_i) =|q_i|^{2k}/2k$ and harmonic coupling potentials $V_2(q_i- q_{i-1}) = (q_i- q_{i-1})^2/2$ between itself and

Izabella Laba, Malabika Pramanik

Let $E\subset\rr$ be a closed set of Hausdorff dimension $α$. We prove that if $α$ is sufficiently close to 1, and if $E$ supports a probabilistic measure obeying appropriate dimensionality and Fourier decay conditions, then $E$ contains non-trivial 3-term arithmetic progressions.

Ely Porat, Amir Rothschild

Group testing is a long studied problem in combinatorics: A small set of $r$ ill people should be identified out of the whole ($n$ people) by using only queries (tests) of the form "Does set X contain an ill human?". In this paper we provide an explicit construction of a testing scheme which is better (smaller) than any known explicit construction. T

Will Dison, Murray Elder, Tim Riley, Robert Young

We prove that the Dehn function of a group of Stallings that is finitely presented but not of type F_3 is quadratic. To appear in Geometric and Functional Analysis.

Thomas W. J. Thompson, Duncan K. Galloway, Richard E. Rothschild, Lee Homer

The low-mass X-ray binary GS 1826-238 is presently unique for its consistently regular bursting behavior. In previous Rossi X-Ray Timing Explorer (RXTE) measurements between 1997 November and 2002 July, this source exhibited (nearly) limit-cycle bursts with recurrence times that decreased proportionately as the persistent flux increased. Here we report addit

Mohsen Asgharzadeh, Massoud Tousi

This paper discusses the connection between the local cohomology modules and the Serre classes of $R$-modules. Such connection provided a common language for expressing some results about the local cohomology $R$-modules, that has appeared in different papers.

Matthias Schuett, Andreas Schweizer

We explicitly determine the elliptic K3 surfaces with a maximal singular fibre. If the characteristic of the ground field is different from 2, for each of the two possible maximal fibre types, $I_{19}$ and $I^*_{14}$, the surface is unique. In characteristic 2 the maximal fibre types are $I_{18}$ and $I^*_{13}$, and there exist two (resp. one) one-parameter

Bruce Hajek

Substitute valuations (in some contexts called gross substitute valuations) are prominent in combinatorial auction theory. An algorithm is given in this paper for generating a substitute valuation through Monte Carlo simulation. In addition, the geometry of the set of all substitute valuations for a fixed number of goods K is investigated. The set consists o

M. Muzychuk, F. Pakovich

In this paper we prove several results about the lattice of imprimitivity systems of a permutation group containing a cyclic subgroup with at most two orbits. As an application we generalize the first Ritt theorem about functional decompositions of polynomials, and some other related results. Besides, we discuss examples of rational functions, related to fin

Pierluigi Contucci, Francesco Unguendoli

We prove two inequalities for the direct and truncated correlation for the nearest-neighboor one-dimensional Edwards-Anderson model with symmetric quenched disorder. The second inequality has the opposite sign of the GKS inequality of type II. In the non symmetric case with positive average we show that while the direct correlation keeps its sign the truncat

Rahul Jain, Ashwin Nayak, Yi Su

The notion of divergence information of an ensemble of probability distributions was introduced by Jain, Radhakrishnan, and Sen in the context of the ``substate theorem''. Since then, divergence has been recognized as a more natural measure of information in several situations in quantum and classical communication. We construct ensembles of probabil

Alessandro Zenesini, Carlo Sias, Hans Lignier, Yeshpal Singh

In this article, we present theoretical as well as experimental results on resonantly enhanced tunneling of Bose-Einstein condensates in optical lattices both in the linear case and for small nonlinearities. Our results demonstrate the usefulness of condensates in optical lattices for simulating Hamiltonians originally used for describing solid state phenome

Maria Laura Barberis, Isabel G. Dotti, Misha Verbitsky

A nilmanifold is a quotient of a nilpotent group $G$ by a co-compact discrete subgroup. A complex nilmanifold is one which is equipped with a $G$-invariant complex structure. We prove that a complex nilmanifold has trivial canonical bundle. This is used to study hypercomplex nilmanifolds (nilmanifolds with a triple of $G$-invariant complex structures which s

Andrey Bogdanov, Vadim Meshkov, Alexander Omelchenko, Michael Petrov

The paper addresses the $k$-tangle enumeration problem. We introduce a notion of cascade diagram for $k$-tangle projections. An effective enumeration algorithm for projections is proposed based on cascade representation. Tangles projections with up to 12 crossings are tabulated. We provide also pictures of alternating $k$-tangles with 5 crossing or less.

Roman V. Baluev

The role of radial velocity (RV) jitter in extrasolar planet search surveys is discussed. Based on the maximum likelihood principle, improved statistical algorithms for RV fitting and period search are developed. These algorithms incorporate a built-in jitter determination, so that resulting estimations of planetary parameters account for this jitter automat

Kai Behrend, Grégory Ginot, Behrang Noohi, Ping Xu

We establish the general machinery of string topology for differentiable stacks. This machinery allows us to treat on an equal footing free loops in stacks and hidden loops. In particular, we give a good notion of a free loop stack, and of a mapping stack $\map(Y,\XX)$, where $Y$ is a compact space and $\XX$ a topological stack, which is functorial both in $

O. Cakir, K. O. Ozansoy

We investigate the effects of unparticles on gamma gamma--> gamma gamma scattering for photon collider mode of the future multi-TeV e^+e^- linear collider. We show the effects of unparticles on the differential, and total scattering cross sections for different polarization configurations. Considering 1-loop Standard Model background contributions from the c

A. Cetoli, E. Lundh

We investigate the behavior of an array of Bose-Einstein condensate tubes described by means of a Bose-Hubbard Hamiltonian. Using an anisotropic non-polynomial Schrodinger equation we link the macroscopic parameters in the Bose-Hubbard Hamiltonian to the ones that are tunable in experiments. Using a mean field approach we predict that increasing the optical

Sandor Varro

The exact analytic solutions of the energy eigenvalue equation of the system consisting of a free electron and one mode of the quantized radiation field are used for studying the physical meaning of a class of number-phase minimum uncertainty states. The states of the mode which minimize the uncertainty product of the photon number and the Susskind and Glogo

Piotr T. Chruściel, Paul Tod

Following an argument proposed by Mason, we prove that there are no algebraically special asymptotically simple vacuum space-times with a smooth, shear-free, geodesic congruence of principal null directions extending transversally to a cross-section of Scri. Our analysis leaves the door open for escaping this conclusion if the congruence is not smooth, or no

D. M. Maranhão, M. S. Baptista, J. C. Sartorelli, I. L. Caldas

The existence of a special periodic window in the two-dimensional parameter space of an experimental Chua's circuit is reported. One of the main reasons that makes such a window special is that the observation of one implies that other similar periodic windows must exist for other parameter values. However, such a window has never been experimentally obs

KLOE Collaboration

Using a sample of over 600 million phi->K+K- decays collected at the Dafne e+e- collider, we have measured with the KLOE detector the absolute branching ratios for the charged kaon semileptonic decays, K+/- -> p0 e nu (gamma) (Ke3) and K+/- -> p0 mu nu (gamma) (Kmu3). The results, BR(Ke3) = 0.04965 +/- 0.00038_{stat} +/- 0.00037_{syst} and BR(Kmu3) = 0.03233

K. Miwa, S. Dairaku, D. Nakajima

The Theta+ was searched for via the K+p -> pi+X reaction using the 1.2 GeV/c K+ beam at the K6 beam line of the KEK-PS 12 GeV Proton Synchrotron. In the missing mass spectrum of the K+p -> pi+X reaction, no clear peak structure was observed. Therefore a 90 % C.L. upper limit of 3.5 ub/sr was derived for the differential cross section averaged over 2degree to

Giovanni Alessandrini, Vincenzo Nesi

We prove necessary and sufficient criteria of invertibility for planar harmonic mappings which generalize a classical result of H. Kneser, also known as the Radó-Kneser-Choquet theorem.