September 2006 arXiv papers — page 33

Jonas Reitz

A new axiom is proposed, the Ground Axiom, asserting that the universe is not a nontrivial set forcing extension of any inner model. The Ground Axiom is first-order expressible, and any model of ZFC has a class forcing extension which satisfies it. The Ground Axiom is independent of many well-known set-theoretic assertions including the Generalized Continuum

Kausik Sengupta, Kartik K Iyer, E. V. Sampathkumaran

The results of dc magnetization, electrical and magnetoresistance and heat capacity measurements (2-300 K) on Tb7Rh3, crystallizing in Th7Fe3-type hexagonal structure, are reported. In this compound, magnetic ordering sets in around 90 K with additional transitions at low temperatures and the temperature coefficient of resistivity (R), dR/dT, is negative ove

Belle colaboration

We present the first observation of tau lepton decays to hadronic final states with a phi-meson. This analysis is based on 401 fb^-1 of data accumulated at the Belle experiment. The branching fraction obtained is B(tau- -> phi K- nu) = (4.05 +- 0.25 +- 0.26) x 10^-5.

Stuart White

In 1960 Pukánszky introduced an invariant associating to every masa in a separable $\mathrm{II}_1$ factor a non-empty subset of $\mathbb N\cup\{\infty\}$. This invariant examines the multiplicity structure of the von Neumann algebra generated by the left-right action of the masa. In this paper it is shown that every non-empty subset of $\mathbb N\cup\{\infty

O. Hudak, F. Cordero, F. Craciun

The PZT material near the morphotropic phase boundary where a monoclinic phase was observed is studied. A theory of the tetragonal to monoclinic phase transition was developed within the Landau free energy approach. The phase transition from the tetragonal to the monoclinic phase is of the first order near the second order. Dielectric response near the phase

Gideon Amir, Christopher Hoffman

Benjamini,Haggstrom, Peres and Steif introduced the model of dynamical random walk on Z^d. This is a continuum of random walks indexed by a parameter t. They proved that for d=3,4 there almost surely exist t such that the random walk at time t visits the origin infinitely often, but for d > 4 there almost surely do not exist such t. Hoffman showed that for d

Xiancong Lu, Yue Yu

We study the thermodynamics of ultracold Bose atoms in optical lattices by numerically diagonalizing the mean-field Hamiltonian of the Bose-Hubbard model. This method well describes the behavior of long-range correlations and therefore is valid deep in the superfluid phase. For the homogeneous Bose-Hubbard model, we draw the finite-temperature phase diagram

Lars Samuelsson, Nils Andersson

Recent observations of quasi-periodic oscillations in the aftermath of giant flares in soft gamma-ray repeaters suggest a close coupling between the seismic motion of the crust after a major quake and the modes of oscillations in a magnetar. In this paper we consider the purely elastic modes of oscillation in the crust of a neutron star in the relativistic C

F. Dolcini, B. Trauzettel, I. Safi, H. Grabert

The electrical current noise of a quantum wire is expected to increase with increasing applied voltage. We show that this intuition can be wrong. Specifically, we consider a single channel quantum wire with impurities and with a capacitive coupling to nearby metallic gates and find that its excess noise, defined as the change in the noise caused by the finit

Nikolai Mnev

Pure combinatorial models for BPL_n and Gauss map of a combinatorial manifold are described.

J. Q. You, Xuedong Hu, S. Ashhab, Franco Nori

A flux qubit can have a relatively long decoherence time at the degeneracy point, but away from this point the decoherence time is greatly reduced by dephasing. This limits the practical applications of flux qubits. Here we propose a new qubit design modified from the commonly used flux qubit by introducing an additional capacitor shunted in parallel to the

Bhalchandra D. Thatte

A pedigree is a directed graph in which each vertex (except the founder vertices) has two parents. The main result in this paper is a construction of an infinite family of counter examples to a reconstruction problem on pedigrees, thus negatively answering a question of Steel and Hein. Some positive reconstruction results are also presented. The problem of c

Jian-da Wu, Jian-lan Chen, Yong-de Zhang

In this paper we show a new way to generate entanglement via two identical three-level atoms splitting in the magnetic field interacting with the cavity field. By the system we investigate, We can acquire the EPR state, multi-dimensional entangled states etc. which are more stable than usual realization by high-energy-level Rydberg atoms and we can realize t

D. A. Kulikov, R. S. Tutik

A recursion technique for the renormalization of semiclassical expansions for the Regge trajectories of bound states of the Schrödinger equation is developed. As an application of the proposed technique, the two-parameter renormalization scheme of the Regge trajectories for the bound states in the Martin potential is considered.

Gabriele Scheler

We are looking at local protein interaction networks from the perspective of directed, labeled graphs with quantitative values for monotonic changes in concentrations. These systems can be used to perform stability analysis for a stable attractor, given initial values. They can also show re-configuration of whole system states by dynamic insertion of links,

Daniel Lawson, Henrik Jeldtoft Jensen

Models relating to the Species-Area curve are usually defined at the species level, and concerned only with ecological timescales. We examine an individual-based model of co-evolution on a spatial lattice based on the Tangled Nature model, and show that reproduction, mutation and dispersion by diffusion in an interacting system produces power-law Species-Are

Ivailo S. Atanasov, Oleg I. Yordanov

We suggest a class of direct sample estimates for the two-point quadratic statistical functions of multidimensional data, which includes: estimates of the sample autocovariance function (AcF), sample mean square increment (also, structure) function, and the estimate of the power spectrum. The central estimate for the class is the sample AcF, which is constru

R. Graebeldinger, P. Schust, M. Mattes, M. Sorg

The practical usefulness of Relativistic Schrödinger Theory (RST) is tested by calculating approximately the energy difference between the excited singlet state $1s2s {}^1S_0$ and the ground state $1s^2 {}^1S_0$ of the helium-like ions with arbitrary charge number $z_{\rm ex} (2\le z_{\rm ex}\le 100)$. The results are compared to the corresponding prediction

S Abd El-Samad, R. Bilger, K. -Th. Brinkmann, H. Clement

The single-pion production reactions $pp\to dπ^+$, $pp\to npπ^+$ and $pp\to ppπ^0$ were measured at a beam momentum of 0.95 GeV/c ($T_p \approx$ 400 MeV) using the short version of the COSY-TOF spectrometer. The implementation of a central calorimeter provided particle identification, energy determination and neutron detection in addition to time-of-flight a

Clemens Foerster

We consider a linear elastic plate with stress-free boundary conditions in the limit of vanishing Poisson coefficient. We prove that under a local change of Young's modulus infinitely many eigenvalues arise in the essential spectrum which accumulate at a positive threshold. We give estimates on the accumulation rate and on the asymptotical behaviour of t

Tadafumi Ohsaku

The deformation quantization of Moyal-Weyl star product of functions of quaternions is investigated.

Dennis DeTurck, Herman Gluck, Daniel Pomerleano, David Shea Vick

The Four Vertex Theorem, one of the earliest results in global differential geometry, says that a simple closed curve in the plane, other than a circle, must have at least four "vertices", that is, at least four points where the curvature has a local maximum or local minimum. In 1909 Syamadas Mukhopadhyaya proved this for strictly convex curves in th

Aditya Mahajan, Demosthenis Teneketzis

A discrete time stochastic feedback control system with a noisy communication channel between the sensor and the controller is considered. The sensor has limited memory. At each time, the sensor transmits encoded symbol over the channel and updates its memory. The controller receives a noisy version of the transmitted symbol, and generates a control action b

Greg Markowsky

In this paper we will examine the derivative of intersection local time of Brownian motion and symmetric stable processes in $R^2$. These processes do not exist when defined in the canonical way. The purpose of this paper is to exhibit the correct rate for renormaliztion of these processes.

Lin Chen, Yi Li, Kefeng Liu

In this note, we use the method of [3] to give a simple proof of famous Witten conjecture. Combining the coefficients derived in our note and this method, we can derive more recursion formulas of Hodge integrals.

D. Hernandez Ruiperez, A. C. Lopez Martin, F. Sancho de Salas

We extend to singular schemes with Gorenstein singularities or fibered in schemes of that kind Bondal and Orlov's criterion for an integral functor to be fully faithful. We also contemplate a criterion for equivalence. We offer a proof that is new even if we restrict to the smooth case. In addition, we prove that for locally projective Gorenstein morphis

Feride Tiglay

We prove that the periodic initial value problem for a modified Euler-Poisson equation is well-posed for initial data in $H^{s} (T^{m})$ when $s>m/2+2$ and we improve the Sobolev index to $s>3/2$ for $m=1$. We also study the analytic regularity of this problem and prove a Cauchy-Kowalevski type theorem. After presenting a formal derivation of the equation on

Stephon H. S. Alexander, Deepak Vaid

It is well known that the covariant coupling of fermionic matter to gravity induces a four-fermion interaction. The presence of this term in a homogenous and isotropic space-time results in a BCS-like Hamiltonian and the formation of a chiral condensate with a mass gap. We calculate the gap ($Δ$) via a mean-field approximation for minimally coupled fermionic

G. V. Dunne, A. Huet, D. Rivera, C. Schubert

We obtain closed-form expressions, in terms of the Faulhaber numbers, for the weak-field expansion coefficients of the two-loop Euler-Heisenberg effective Lagrangians in a magnetic or electric field. This follows from the observation that the magnetic worldline Green's function has a natural expansion in terms of the Faulhaber numbers.

F. Bazzocchi, J. W. F. Valle

Neutrino mass generation may affect the basic structure of the electroweak symmetry breaking sector. We consider a broad class of elementary particle theories where neutrinos get mass at a low mass scale. We show how these can be made natural up to few TeV or so, in the absence of supersymmetry or other possible stabilizing mechanisms. Although the standard

P. D. Welch

We analyse the extent of possible computations following Hogarth in Malament-Hogarth (MH) spacetimes, and Etesi and Németi in the special subclass containing rotating Kerr black holes. Hogarth had shown that any arithmetic statement could be resolved in a suitable MH spacetime. Etesi and Nemeti had shown that some \forall \exists relations on natural numbers

V. N. Zavaritsky

Our comprehensive analysis suggests the heating origin of key findings by the authors of the commented letter, hence rendering irrelevant their conclusions.

Kausik Sengupta, E. V. Sampathkumaran

The compound, Nd7Rh3, crystallizing in Th7Fe3-type hexagonal structure, has been shown recently by us to exhibit a signature of magnetic phase-coexistence phenomenon below 10 K after a field cycling, uncharacteristic of stoichiometric intermetallic compounds, bearing a relevance to the trends in the field of electronic phase-separation. In order to character

V. A. Trepakov, M. L. Savinov, V Zelezny, P. P. Syrnikov

Dielectric permittivity and infrared reflectivity spectra of Li doped KNbO3 single crystals have been studied for the first time for K1-xLixNbO3 (KLN) with x = 0.015, 0.02, 0.065. It was found that like in KTaO3, Li admixture results in appearance of dielectric relaxation with the relaxation parameters very close to those in KTaO3 quantum paraelectric. It wa

Anders Mathias Lunde, Karsten Flensberg, Leonid I. Glazman

We study the effect of electron-electron interaction on the transport properties of short clean quantum wires adiabatically connected to reservoirs. Interactions lead to resonances in a multi-channel wire at particular values of the Fermi energy. We investigate in detail the resonance in a two-channel wire. The (negative) conductance correction peaks at the

Eran Bouchbinder, Itamar Procaccia

The stability of a rapid dynamic crack in a two dimensional infinite strip is studied in the framework of Linear Elasticity Fracture Mechanics supplemented with a modified principle of local symmetry. It is predicted that a single crack becomes unstable by a finite wavelength oscillatory mode at a velocity $v_c$, $0.8c_R<v_c<0.85c_R$, where $c_R$ is the Rayl

Kevin Krisciunas, Peter M. Garnavich, Vallery Stanishev, Nicholas B. Suntzeff

We present optical (UBVRI) and near-infrared (YJHK) photometry of the normal Type Ia supernova 2004S. We also present eight optical spectra and one near-IR spectrum of SN 2004S. The light curves and spectra are nearly identical to those of SN 2001el. This is the first time we have seen optical and IR light curves of two Type Ia supernovae match so closely. W

Nevin N. Weinberg, Lars Bildsten, Edward F. Brown

We calculate the thermal and dynamical evolution of the surface layers of an accreting neutron star during the rise of a superburst. For the first few hours following unstable 12C ignition, the nuclear energy release is transported by convection. However, as the base temperature rises, the heating time becomes shorter than the eddy turnover time and convecti

Kunwar Alkendra Pratap Singh

The effects of radiative losses due to Newtonian cooling and MHD turbulence have been considered to examine the spatial damping of linear compressional waves in quiescent prominences and prominence-corona transition region (PCTR). The radiative losses give acceptable damping lengths for the slow mode wave for the radiative relaxation time in the range (10-10

Sofia Feltzing

The current knowledge of the abundance structure in the Milky Way is reviewed. Special emphasis is put on recent results for stars with kinematics typical of the thin and the thick disks, respectively, and how these results can, apart from studying the Milky Way also give information about the origin of the elements. Two on-going studies are high-lighted. On

Pedro F. Gonzalez-Diaz, Alberto Rozas-Fernandez

By using an unmodified Einstein gravity theory it is shown that all of the speeding-up effects taking place in the current universe are entirely due to the quantum effects associated with the background radiation or to the combination of such effects with those derived from the presence of a cosmological constant, without invoking any dynamic dark energy com

I. Rogachevskii, N. Kleeorin, E. Liverts

The nonlinear mean-field dynamo due to a shear-current effect in a nonhelical homogeneous turbulence with a mean velocity shear is discussed. The transport of magnetic helicity as a dynamical nonlinearity is taken into account. The shear-current effect is associated with the ${\bf W} {\bf \times} {\bf J}$ term in the mean electromotive force, where ${\bf W}$

Kristian S. Thygesen, Angel Rubio

Correlation effects within the GW approximation have been incorporated into the Keldysh non-equilibrium transport formalism. We show that GW describes the Kondo effect and the zero-temperature transport properties of the Anderson model fairly well. Combining the GW scheme with density functional theory and a Wannier function basis set, we illustrate the impa

G. A. El, Yu. G. Gladush, A. M. Kamchatnov

Stationary periodic solutions of the two-dimensional Gross-Pitaevskii equation are obtained and analyzed for different parameter values in the context of the problem of a supersonic flow of a Bose-Einstein condensate past an obstacle. The asymptotic connections with the corresponding periodic solutions of the Korteweg-de Vries and nonlinear Schrödinger equat

Ira B. Schwartz, Leah B. Shaw

We consider small network models for mutually delay-coupled systems which typically do not exhibit stable isochronally synchronized solutions. We show that for certain coupling architectures which involve delayed self feedback to the nodes, the oscillators become isochronally synchronized. Applications are shown for both incoherent pump coupled lasers and sp

Clifton Cunningham, Julia Gordon

We give a motivic proof of a character formula for depth zero supercuspidal representations of $p$-adic SL(2). We begin by finding the virtual Chow motives for the character values of all depth zero supercuspidal representations of $p$-adic SL(2), at topologically unipotent elements. Then we find the virtual Chow motives for the values of the Fourier transfo

M. S. Cunha, R. R. Landim, C. A. S. Almeida

In this work we study a nonlinear gauged O(3)-sigma model with both minimal and nonminimal coupling in the covariant derivative. Using an asymmetric scalar potential, the model is found to exhibit both topological and non-topological soliton solutions in the Bogomol&#39;nyi limit.

Brian J. Morsony, Davide Lazzati, Mitchell C. Begelman

We study the long-term evolution of relativistic jets in collapsars and examine the effects of viewing angle on the subsequent gamma ray bursts. We carry out a series of high-resolution simulations of a jet propagating through a stellar envelope in 2D cylindrical coordinates using the FLASH relativistic hydrodynamics module. For the first time, simulations a

Gerardo Adesso, Alessio Serafini, Fabrizio Illuminati

We present a novel, detailed study on the usefulness of three-mode Gaussian states states for realistic processing of continuous-variable quantum information, with a particular emphasis on the possibilities opened up by their genuine tripartite entanglement. We describe practical schemes to engineer several classes of pure and mixed three-mode states that st

W. Oelert, H. -H. Adam, A. Budzanowski, E. Czerwinski

Simple--minded thoughts about the cross sections for the reactions pp-->ppK+K- and pp-->ppK0K0 are presented, which certainly do not account for the complex coupled channel problem but rather provide some ideas into the mutual reaction dynamics.

Elcio Abdalla, Cecilia B. M. H. Chirenti, Alberto Saa

We consider here scalar and electromagnetic perturbations for the Vaidya metric in double-null coordinates. Such an approach allows one to go a step further in the analysis of quasinormal modes for time-dependent spacetimes. Some recent results are refined, and a new non-stationary behavior corresponding to some sort of inertia for quasinormal modes is ident

Viacheslav V. Nikulin

After results by the author (1980, 1981), and by Vinberg (1981), finiteness of the number of maximal arithmetic reflection groups in Lobachevsky spaces was not known in dimensions $2\le n\le 9$ only. Recently (2005), the finiteness was proved in dimension 2 by Long, Maclachlan and Reid, and in dimension 3 by Agol. Here we use these results in dimensions 2 an

Yongcheng Yin, Yu Zhai

In this paper, we prove that a rational map with a Cantor Julia set carries no invariant line fields on its Julia set. It follows that a structurally stable rational map with a Cantor Julia set is hyperbolic.

Liping Guo, Yunbo Zhang, Shu Chen

We investigate the ground state properties of an equal mixture of two species of bosons in its Mott-insulator phase at a filling factor two per site. We identify one type of spin triplet-singlet transition through the competition of ground state. When the on-site interaction is weak ($U<U_c$) the two particles prefer to stay in the lowest band and with weak

Ozgur Cakir, Toshihide Takagahara

Hyperfine interaction of electron spins with nuclear spins, in coupled double quantum dots is studied. Results of successive electron spin measurements exhibit bunching due to correlations induced via the nuclear spins. Further nuclear spins can be purified via conditional electron spin measurements which lead to electron spin revivals in the conditional pro

Mal--Soon Lee, S. Gowtham, Haiying He, Kah--Chun Lau

The first--principles density functional molecular dynamics simulations have been carried out to investigate the geometric, the electronic, and the finite temperature properties of pure Li clusters (Li$_{10}$, Li$_{12}$) and Al--doped Li clusters (Li$_{10}$Al, Li$_{10}$Al$_2$). We find that addition of two Al impurities in Li$_{10}$ results in a substantial

H. Itoyama, H. Kihara, R. Yoshioka

We evaluate partition functions of matrix models which are given by topologically twisted and dimensionally reduced actions of d=4 N=1 super Yang-Mills theories with classical (semi-)simple gauge groups, SO(2N), SO(2N+1) and USp(2N). The integrals reduce to those over the maximal tori by semi-classical approximation which is exact in reduced models. We carry

Qin Lu, Yu-Ping Kuang

Hadronic transitions of the chi(cj)(1P) states have not been studied yet. We calculate the rate of the hadronic transition chi(c1)(1P) to eta(c) plus two pions in the framework of QCD multipole expansion. We show that this process can be studied experimentally at the upgraded Beijing Spectrometer BES III and the Cornell CLEO-c.

Sergio Boixo, Lorenza Viola, Gerardo Ortiz

We investigate the connection between quasi-classical (pointer) states and generalized coherent states (GCSs) within an algebraic approach to Markovian quantum systems (including bosons, spins, and fermions). We establish conditions for the GCS set to become most robust by relating the rate of purity loss to an invariant measure of uncertainty derived from q

Luciano da Fontoura Costa, Francisco Aparecido Rodrigues, Gonzalo Travieso

Even more interesting than the intricate organization of complex networks are the dynamical behavior of systems which such structures underly. Among the many types of dynamics, one particularly interesting category involves the evolution of trails left by moving agents progressing through random walks and dilating processes in a complex network. The emergenc

Eitan Tadmor, Dongming Wei

We prove that the one-dimensional Euler-Poisson system driven by the Poisson forcing together with the usual &gamma;-law pressure, &gamma; &geq; 1, admits global solutions for a large class of initial data. Thus, the Poisson forcing regularizes the generic finite-time breakdown in the 2x2 p-system. Global regularity is shown to depend on whether or not the i

Zoltan Imre Szabo

This paper evolves a new non-perturbative theory by which the problem of infinities appearing in quantum physics can be handled. Its most important application is an exact derivation of the Lamb shift formula by using no renormalization. The Lamb shift experiment (1947) gave rise to one of the greatest challenges whose explanation brought the modern renormal

Fedor Herbut

Schroedinger&#39;s disentanglement [E. Schroedinger, Proc. Cambridge Phil. Soc. 31, 555 (1935)], i. e., remote state decomposition, as a physical way to study entanglement, is carried one step further with respect to previous work in investigating the qualitative side of entanglement in any bipartite state vector. Remote measurement (or, equivalently, remote

Peter Henselder

Deforming the algebraic structure of geometric algebra on the phase space with a Moyal product leads naturally to supersymmetric quantum mechanics in the star product formalism.

N. L. Chuprikov

The origin of nonlocality in quantum mechanics (QM) is analyzed from the viewpoint of our new model of a one-dimensional (1D) completed scattering. Our study of quantum nonlocality complements those carried out by Volovich and Khrennikov. They pointed to an unphysical character of nonlocality in Bell&#39;s theorem whose context does not contain the very stru

Gerardo Adesso, Marie Ericsson

Gaussian matrix product states are obtained as the outputs of projection operations from an ancillary space of M infinitely entangled bonds connecting neighboring sites, applied at each of N sites of an harmonic chain. Replacing the projections by associated Gaussian states, the &#39;building blocks&#39;, we show that the entanglement range in translationall

T. Pfeifer, M. C. Downer

We report the direct observation of periodic intensity modulation of a laser pulse propagating in a hollow core waveguide. A series of equally spaced plasma sparks along the gas-filled capillary is produced. This effect can be explained by the beating of different fiber modes, which are excited by controlling the size of the focal spot at the capillary entra

Xavier Castelló, Víctor M. Eguíluz, Maxi San Miguel

We consider a modification of the voter model in which a set of interacting elements (agents) can be in either of two equivalent states (A or B) or in a third additional mixed AB state. The model is motivated by studies of language competition dynamics, where the AB state is associated with bilingualism. We study the ordering process and associated interface

Kwang-Hua W. Chu

We make remarks on Fernández Guasti&#39;s paper [{\it J. Phys. A: Math. Gen.} 39 (2006) 11825-11832] by pointing out some mistakes Fernández Guasti derived therein.

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

The problem of Freeze Out (FO) in relativistic heavy ion reactions is addressed. We develop and analyze an idealized one-dimensional model of FO in a finite layer, based on the covariant FO probability. The resulting post FO phase-space distributions are discussed for different FO probabilities and layer thicknesses.

Peter Henselder

Superanalysis can be deformed with a fermionic star product into a Clifford calculus that is equivalent to geometric algebra. With this multivector formalism it is then possible to formulate Riemannian geometry and an inhomogeneous generalization of exterior calculus. Moreover it is shown here how symplectic and Poisson geometry fit in this context. The appl

Andrzej M. Frydryszak

We introduce specific type of hyperbolic spaces. It is not a general linear covariant object, but of use in constructing nilpotent systems. In the present work necessary definitions and relevant properties of configuration and phase spaces are indicated. As a working example we use a D=2 isotropic harmonic oscillator.

Pavel Mnev

We give a new proof of the trace formula for regular graphs. Our approach is inspired by path integral approach in quantum mechanics, and calculations are mostly combinatorial.

Dragomir Z. Djokovic

We work over a field K of characteristic zero. The Poincare series for the algebra C_{n,2} of GL_n-invariants and the algebra T_{n,2} of GL_n-concomitants of two generic n x n matrices x and y are presented for n less than or equal 6. Both simply graded and bigraded cases are included. The cases for n at most 4 were known previously. If n=5 or 6, we show tha

K. Gowri Navada

Here we give a necessary and sufficient condition for a Banach space to be separable.

A. Vershik

We give a new (inductive) proof of the classical Frobenius--Young correspondence between irreducible complex representations of the symmetric group and Young diagrams, using the new approach, suggested in \cite{OV, VO}, to determining this correspondence. We also give linear relations between Kostka numbers that follow from the decomposition of the restricti

Fuquan Fang, Yuguang Zhang, Zhenlei Zhang

In this paper we study non-singular solutions of Ricci flow on a closed manifold of dimension at least 4. Amongst others we prove that, if M is a closed 4-manifold on which the normalized Ricci flow exists for all time t>0 with uniformly bounded sectional curvature, then the Euler characteristic $χ(M)\ge 0$. Moreover, the 4-manifold satisfies one of the foll

Hanspeter Kraft, Gerald W. Schwarz

Let $G$ be a finite group and $ϕ\colon V\to W$ an equivariant morphism of finite dimensional $G$-modules. We say that $ϕ$ is faithful if $G$ acts faithfully on $ϕ(V)$. The covariant dimension of $G$ is the minimum of the dimension of $\bar{ϕ(V)}$ taken over all faithful $ϕ$. In this paper we investigate covariant dimension and are able to determine it for ab

Ural Bekbaev

An differential field $(F;\partial_1,...,\partial_m)$ of characteristic zero, a subgroup $H$ of affine group $ GL(n,C)\propto C^n$ with respect to its identical representation in $F^n$ and the following two fields of differential rational functions in $x=(x_1,x_2,...,x_n)$-column vector, $$C< x, \partial >^H=\{f^{\partial}< x> \in C< x, \partial> : f^{\parti

Ye Li

We obtain a local volume growth for complete, noncompact Riemannian manifolds with small integral bounds and with Bach tensor having finite $L^2$ norm in dimension 4.

Weigen Yan, Yeong-Nan Yeh

In this paper we prove that two quantities relating to the length of permutations defined on trees are independent of the structures of trees. We also find that these results are closely related to the results obtained by Graham and Pollak (Bell System Tech. J. 50(1971) 2495--2519) and by Bapat, Kirkland, and Neumann (Linear Alg. Appl. 401(2005) 193--209).

N. Garofalo, D. Danielli, D. M. Nhieu

We provide a partial solution to the isoperimetric problem in the Heisenberg group.

Zhi-Wei Sun

A positive integer n is called a covering number if there are some distinct divisors n_1,...,n_k of n greater than one and some integers a_1,...,a_k such that Z is the union of the residue classes a_1(mod n_1),...,a_k(mod n_k). A covering number is said to be primitive if none of its proper divisors is a covering number. In this paper we give some sufficient

G. Griffith Elder, Jeffrey J. Hooper

Quaternion extensions are often the smallest extensions to exhibit special properties. In the setting of the Hasse-Arf Theorem, for instance, quaternion extensions are used to illustrate the fact that upper ramification numbers need not be integers. These extensions play a similar role in Galois module structure. To better understand these examples, we catal

Alina Marian, Dragos Oprea

We construct a virtual fundamental class on the Quot scheme parametrizing quotients of a trivial bundle on a curve. We use the virtual localization formula to calculate virtual intersection numbers on Quot. As a consequence, we reprove the Vafa-Intriligator formula; our answer is valid even when the Quot scheme is badly behaved. More intersections are comput

D. Kaledin

We assume given a smooth symplectic (in the algebraic sense) resolution $X$ of an affine algebraic variety $Y$, and we prove that, possibly after replacing $Y$ with an etale neighborhood of a point, the derived category of coherent sheaves on $X$ is equivalent to the dervied category of finitely generated left modules over a non-commutative algebra $R$, a no

Hao Pan, Zhi-Wei Sun

Let A={a_s+n_sZ}_{s=1}^k be a finite system of arithmetic sequences which forms an m-cover of Z (i.e., every integer belongs at least to m members of A). In this paper we show the following sharp result: For any positive integers m_1,...,m_k and theta in [0,1), if there is a subset I of {1,...,k} such that the fractional part of sum_{s in I}m_s/n_s is theta,

Hanspeter Kraft

A classical result from 1861 due to Hermite says that every separable equation of degree 5 can be transformed into an equation of the form x^5 + b x^3 + c x + d = 0. Later this was generalized to equations of degree 6 by Joubert. We show that both results can be understood as an explicit analysis of certain covariants of the symmetric groups S_5 and S_6. In

David Sanders, Chris Riley, Lucien Cremaldi, Don Summers

In today&#39;s marketplace, the cost per Terabyte of disks with EIDE interfaces is about a third that of disks with SCSI. Hence, three times as many particle physics events could be put online with EIDE. The modern EIDE interface includes many of the performance features that appeared earlier in SCSI. EIDE bus speeds approach 33 Megabytes/s and need only be

Vladimir Vovk

Competitive on-line prediction (also known as universal prediction of individual sequences) is a strand of learning theory avoiding making any stochastic assumptions about the way the observations are generated. The predictor&#39;s goal is to compete with a benchmark class of prediction rules, which is often a proper Banach function space. Metric entropy pro

W. Zhou, T. Yildirim

By combining neutron inelastic scattering (NIS) and first-principles calculations, we have investigated the lattice dynamics of MOF5. The structural stability of MOF5 was evaluated by calculating the three cubic elastic constants. We find that the shear modulus, c44 = 1.16 GPA, is unusually small, while two other moduli are relatively large (i.e. c11 = 29.42

X. S. Wu, P. W. Adams, G. Catelani

We present low temperature tunneling density of states measurements of Pauli-limited Al films in which the Zeeman and orbital contributions to the critical field are comparable. We show that films in the thickness range of 6-7 nm exhibit a reentrant parallel critical field transition which is associated with a high entropy superconducting phase, similar to t

Andrea Alu, Mario Silveirinha, Alessandro Salandrino, Nader Engheta

In this work, we investigate the response of epsilon-near-zero (ENZ) metamaterials and plasmonic materials to electromagnetic source excitation. The use of these media for tailoring the phase of radiation pattern of arbitrary sources is proposed and analyzed numerically and analytically for some canonical geometries. In particular, the possibility of employi

Limin Yang, Yunbo Zhang

We study the macroscopic quantum tunneling of magnetization of the F=1 spinor condensate interacting through dipole-dipole interaction with an external magnetic field applied along the longitudinal or transverse direction. We show that the ground state energy and the effective magnetic moment of the system exhibit an interesting macroscopic quantum oscillati

Khee-Kyun Voo, C. S. Chu

It is shown in this paper that for open systems, states which are localized in space, discrete in energy, and embedded in the continuum of extended states, can be sustained by low-dimensional and channeled leads. These states have an origin different from that of analogous states discussed by J. von Neumann and E. Wigner [Phys. Z., vol. 30, 465 (1929)]. A fe

Nikolai V. Brilliantov, Thorsten Poeschel, W. Till Kranz, Annette Zippelius

In a granular gas of rough particles the axis of rotation is shown to be correlated with the translational velocity of the particles. The average relative orientation of angular and linear velocities depends on the parameters which characterise the dissipative nature of the collision. We derive a simple theory for these correlations and validate it with nume

Naoko Nakagawa, Teruhisa S. Komatsu

We show that a mesoscopic system such as Feynman&#39;s ratchet may operate as a heat pump, and clarify a underlying physical picture. We consider a system of a particle moving along an asymmetric periodic structure . When put into a contact with two distinct heat baths of equal temperature, the system transfers heat between two baths as the particle is dragg

Teruhisa S. Komatsu, Naoko Nakagawa

We study a class of heat engines including Feynman&#39;s ratchet, which exhibits a directed motion of a particle in nonequilibrium steady states maintained by two heat baths. We measure heat transfer from each heat bath separately, and average them using a careful procedure that reveals the nature of the heat transfer associated with directed steps of the pa

Herman J. Mosquera Cuesta, Carlos A. Bonilla Quintero, M. Habib Dumet, Cristina Furlanetto

In this {\sl Letter} we construct the Hubble diagram (HD) for the standard Friedmann-Lemaître-Robertson-Walker (FLRW) cosmological model after enforcing it with the general relativistic energy conditions, heeding to investigate whether it still stands on as the leading scenario for cosmology in face of the distance modulus-redshift relation of a sample of GR

S. Karpov, G. Beskin, A. Biryukov, V. Debur

The fine structure and the variations of the optical pulse shape and phase of the Crab pulsar are studied on various time scales. The observations have been carried out on 4-m William Hershel and 6-m BTA telescopes with APD photon counter, photomultiplier based 4-channel photometer and PSD based panoramic spectrophotopolarimeter with 1$μ$s time resolution in