February 2007 arXiv papers — page 7

E. Agliari, R. Burioni, D. Cassi, F. M. Neri

A model for information spreading in a population of $N$ mobile agents is extended to $d$-dimensional regular lattices. This model, already studied on two-dimensional lattices, also takes into account the degeneration of information as it passes from one agent to the other. Here, we find that the structure of the underlying lattice strongly affects the time

Keisuke Yamada, Shinya Kasai, Yoshinobu Nakatani, Kensuke Kobayashi

A magnetic vortex is a curling magnetic structure realized in a ferromagnetic disk, which is a promising candidate of a memory cell for future nonvolatile data storage devices. Thus, understanding of the stability and dynamical behaviour of the magnetic vortex is a major requirement for developing magnetic data storage technology. Since the experimental proo

Y. Zhang, H. X. Yang, C. Ma, H. F. Tian

The structural features of the charge ordering states in LuFe2O4 are characterized by in-situ cooling TEM observations from 300K down to 20K. Two distinctive structural modulations, a major q1= (1/3, 1/3, 2) and a weak q2=q1/10 + (0, 0, 3/2), have been well determined at the temperature of 20K. Systematic analysis demonstrates that the charges at low tempera

Yoshiki Imai, Tetsuro Saso

Magnetic properties under the external field are investigated in low-carrier two-band systems, which may explain the nontrivial phase boundary found in temperature vs. magnetic field diagram discovered in some materials, such as filled-skutterudite compound CeOs$_{4}$Sb$_{12}$. Analysis is made both for the periodic Anderson model with the small-dispersive $

Satoshi Fujimoto

This article is a pedagogical review of theoretical studies of noncentrosymmetric superconductors with particular emphasis on the role played by electron correlation, which is important for heavy fermion systems. We survey unique properties of parity-violated superconductivity such as the admixture of spin singlet and triplet states, unusual paramagnetism, l

Katsuhiro Nishinari, Ken Sugawara, Toshiya Kazama, Andreas Schadschneider

Models for the behavior of ants and pedestrians are studied in an unified way in this paper. Each ant follows pheromone put by preceding ants, hence creating a trail on the ground, while pedestrians also try to follow others in a crowd for efficient and safe walking. These following behaviors are incorporated in our stochastic models by using only local upda

H. J. Chang, T. W. Chen, J. W. Chen, W. C. Hong

The lateral current-induced spin polarization in InGaN/GaN superlattices (SLs) without an applied magnetic field is reported. The fact that the sign of the nonequilibrium spin changes as the current reverses and is opposite for the two edges provides a clear signature for the spin Hall effect. In addition, it is discovered that the spin Hall effect can be st

Jize Zhao, Kazuo Ueda, Xiaoqun Wang

We study a one-dimensional SU(N) Hubbard model with an attractive on-site interaction and $N>2$ at half-filling on the bipartite lattice using density-matrix renormalization-group method and a perturbation theory. We find that the ground state of the SU(N) Hubbard model is a charge density wave state with two-fold degeneracy. All the excitations are found to

Stefan Scheel, Rachele Fermani, E. A. Hinds

We investigate the feasibility of using ultracold neutral atoms trapped near a thin superconductor to study vortex noise close to the Kosterlitz-Thouless-Berezinskii transition temperature. Alkali atoms such as rubidium probe the magnetic field produced by the vortices. We show that the relaxation time $T_1$ of the Zeeman sublevel populations can be convenie

I. H. Inoue, S. Yasuda, H. Akinaga, H. Takagi

Exotic features of a metal/oxide/metal (MOM) sandwich, which will be the basis for a drastically innovative nonvolatile memory device, is brought to light from a physical point of view. Here the insulator is one of the ubiquitous and classic binary-transition-metal oxides (TMO), such as Fe2O3, NiO, and CoO. The sandwich exhibits a resistance that reversibly

Dmitri A. Uzdensky

I present a novel view on the problem of solar coronal heating. In my picture, coronal heating should be viewed as a self-regulating process that works to keep the coronal plasma marginally collisionless. The self-regulating mechanism is based on the interplay between two effects: (1) Plasma density controls coronal energy release via the transition between

Matthew Bailes

Binary and Millisecond pulsars have a great deal to teach us about stellar evolution and are invaluable tools for tests of relativistic theories of gravity. Our understanding of these objects has been transformed by large-scale surveys that have uncovered a great deal of new objects, exquisitely timed by ever-improving instrumentation. Here we argue that the

David Lafreniere, Christian Marois, Rene Doyon, Daniel Nadeau

Direct imaging of exoplanets is limited by bright quasi-static speckles in the point spread function (PSF) of the central star. This limitation can be reduced by subtraction of reference PSF images. We have developed an algorithm to construct an optimized reference PSF image from a set of reference images. This image is built as a linear combination of the r

N. A. Patel, S. Curil, Q. Zhang, T. K. Sridharan

Using the Submillimeter Array (SMA) we have imaged for the first time the 321.226 GHz, 10_{29}-9_{36} ortho-H2O maser emission. This is also the first detection of this line in the Cepheus A high-mass star-forming region. The 22.235 GHz, 6_{16}-5_{23} water masers were also observed with the Very Large Array 43 days following the SMA observations. Three of t

Simon Portegies Zwart, Evghenii Gaburov, Hui-Chen Chen, M. Atakan Gürkan

We study the evolution of the mass function in young and dense star clusters by means of direct N-body simulations. Our main aim is to explain the recent observations of the relatively flat mass function observed near the centre of the Arches star cluster. In this region, the power law index of the mass function for stars more massive than about 5-6 solar ma

M. Tafalla

Dense cores are the simplest star-forming sites that we know, but despite their simplicity, they still hold a number of mysteries that limit our understanding of how solar-type stars form. ALMA promises to revolutionize our knowledge of every stage in the life of a core, from the pre-stellar phase to the final disruption by the newly born star. This contribu

A. Janiuk, B. Czerny

We develop a two-flow model of accretion onto a black hole which incorporates the effect of the local magneto-rotational instability. The flow consists of an accretion disk and an accreting corona, and the local dynamo affects the disk/corona mass exchange. The model is aimed to explain the power spectrum density of the sources in their soft, disk-dominated

F. Massi, M. De Luca, D. Elia, T. Giannini

The Vela Molecular Ridge is one of the nearest intermediate-mass star forming regions, located within the galactic plane and outside the solar circle. Cloud D, in particular, hosts a number of small embedded young clusters. We present the results of a large-scale map in the dust continuum at 1.2 mm of a ~ 1deg x 1deg area within cloud D. The main aim of the

R. W. Goosmann, B. Czerny, V. Karas, M. Dovciak

We discuss implications of a strong flare event observed in the Seyfert galaxy MCG-6-30-15 assuming that the emission is due to localized magnetic reconnection. We conduct detailed radiative transfer modeling of the reprocessed radiation for a primary source that is elevated above the disk. The model includes relativistic effects and Keplerian motion around

R. W. Goosmann, B. Czerny, V. Karas, G. Ponti

We propose a reflection model of the time delays detected during an exceptionally bright, single flare in MCG-6-30-15. We consider a scenario in which the delays of the hard X-rays with respect to the soft X-rays are caused by the presence of the delayed reflection component. We employ a model of the flare, which is accompanied by reprocessed emission. We co

Yongquan Xue, Wei Cui

[Context] The broadband spectral energy distribution of microquasars has proven to be a valuable tool for assessing the roles of jets and accretion flows in microquasars, as well as the coupling between the two. The coupling might manifest itself observationally in the correlated radio and X-ray variabilities of a source. Such a radio/X-ray correlation has i

Edward Pope, Christian Kaiser, Georgi Pavlovski, Hans Fangohr

The results of hydrodynamic simulations of the Virgo and Perseus clusters suggest that thermal conduction is not responsible for the observed temperature and density profiles. As a result it seems that thermal conduction occurs at a much lower level than the Spitzer value. Comparing cavity enthalpies to the radiative losses within the cooling radius for seve

A. Voegler, M. Schuessler

Context: Observations indicate that the `quiet' solar photosphere outside active regions contains considerable amounts of magnetic energy and magnetic flux, with mixed polarity on small scales. The origin of this flux is unclear. Aims: We test whether local dynamo action of the near-surface convection (granulation) can generate a significant contribution

Felix Aharonian

The undisputed galactic origin of cosmic rays at energies below the so-called knee implies an existence of a nonthemal population of galactic objects which effectively accelerate protons and nuclei to TeV-PeV energies. The distinct signatures of these cosmic accelerators are high energy neutrinos and gamma-rays produced through hadronic interactions. While g

A. A. Smirnova, N. Gavrilovic, A. V. Moiseev, L. C. Popovic

We present an analysis of 3D spectra of Mrk 533, observed with the integral-field spectrograph MPFS and using the Fabry Perot Interferometer (FPI) of the SAO RAS 6-m telescope. We found emissions of gas from the active Sy 2 nucleus in the centre and also from the HII regions in a spiral structure and a circumnuclear region. The gas kinematics shows regular n

Yoshiaki Hagiwara

Sub-arcsecond observations using the Very Large Array (VLA) are presented for low-luminosity water maser in M82, M51, and NGC4051. New maser features have been detected within the M82 starburst complex. They are largely associated with star-forming activity, such as optically identified starburst-driven winds, H II regions, or the early phase of star formati

Kun Ma, W. Y. Cui, B. Zhang

The primary nature of the $^{13}$C neutron source is very significant for the studies of the s-process nucleosynthesis. In this paper we present an attempt to fit the element abundances observed in 16 s-rich stars using parametric model of the single neutron exposure. The calculated results indicate that almost all s-elements were made in a single neutron ex

W. Y. Cui, B. Zhang, K. Ma, L. Zhang

The s-enhanced and very metal-poor star CS 30322-023 shows a puzzling abundance pattern of the neutron-capture elements, i.e. several neutron-capture elements such as Ba, Pb etc. show enhancement, but other neutron-capture elements such as Sr, Eu etc. exhibit deficient with respect to iron. The study to this sample star could make people gain a better unders

Y. B. Kang, S. -L. Kim, S. -C. Rey, C. -U. Lee

Time-series CCD photometric observations of the intermediate-age open cluster NGC 2099 were performed to search for variable stars. We also carried out BV photometry to study physical properties of variables in the cluster. Using V-band time-series data, we carefully examined light variations of about 12,000 stars in the range of 10 < V < 22 mag. A total of

Donald C. Ellison, Daniel J. Patnaude, Patrick Slane, Pasquale Blasi

If highly efficient, cosmic ray production can have a significant effect on the X-ray emission from SNRs as well as their dynamical evolution. Using hydrodynamical simulations including diffusive shock acceleration, we produce spectra for both the thermal and nonthermal forward shock emission. For a given ambient density and explosion energy, we find that th

S. L. Breen, S. P. Ellingsen, M. Johnston-Hollitt, S. Wotherspoon

We report the results of a blind search for 22-GHz water masers in two regions, covering approximately half a square degree, within the giant molecular cloud associated with RCW 106. The complete search of the two regions was carried out with the 26-m Mount Pleasant radio telescope and resulted in the detection of nine water masers, five of which are new det

Xue-Guang Zhang, Dultzin-Hacyan D., Ting-Gui Wang

In this paper we study the object SDSS J1130+0058 which is the only AGN known to have both double-peaked low-ionization broad emission lines, and also X-shaped radio structures. Emission from an accretion disk can reproduce the double-peaked line profile of broad H$α$, but not the radio structure. Under the accretion disk model, the period of the inner emiss

Sabino Matarrese, Massimo Pietroni

A semi-analytic approach to the computation of the non-linear power-spectrum of dark matter density fluctuations is proposed. The method is based on the Renormalization Group technique and can be applied to any underlying cosmological model. Our prediction on the baryonic acoustic oscillations in a LambdaCDM model accurately fits the results of N-body simula

Elisabetta Bissaldi, Francesco Calura, Francesca Matteucci, Francesco Longo

It has been established that Gamma-Ray Bursts (GRBs) are connected to Supernovae (SNe) explosions of Type Ib/c. We intend to test whether the hypothesis of Type Ib/c SNe from different massive progenitors can reproduce the local GRB rate as well as the GRB rate as a function of redshift. We aim to predict the GRB rate at very high redshift under different as

Sergei Treil, Brett Wick

The main result of the paper is the theorem giving a sufficient condition for the existence of a bounded analytic projection onto a holomorphic family of (generally infinite-dimensional) subspaces (a holomorphic sub-bundle of a trivial bundle). This sufficient condition is also necessary in the case of finite dimension or codimension of the bundle. A simple

Igor Savukov, Dmitry Budker

We describe procedures for constructing inexpensive waveplates of desired retardation out of ordinary commercially available transparencies. Various relevant properties of the transparencies are investigated: the dependence of retardation on rotation of the film, tilt, wavelength, position, and temperature. Constructing waveplates out of combinations of tran

Mark Friesen, Asoka Biswas, Xuedong Hu, Daniel Lidar

We propose an experimentally feasible architecture with controllable long-range couplings built up from local exchange interactions. The scheme consists of a spin-bus, with strong, always-on interactions, coupled dynamically to external qubits of the Loss and DiVincenzo type. Long-range correlations are enabled by a spectral gap occurring in a finite-size ch

Maria A. Avino-Diaz

In this paper we introduce the idea of probability in the definition of Sequential Dynamical Systems, thus obtaining a new concept, Probabilistic Sequential System. The introduction of a probabilistic structure on Sequential Dynamical Systems is an important and interesting problem. The notion of homomorphism of our new model, is a natural extension of homom

Manuela Campanelli, Carlos O. Lousto, Yosef Zlochower, David Merritt

Recent calculations of gravitational radiation recoil generated during black-hole binary mergers have reopened the possibility that a merged binary can be ejected even from the nucleus of a massive host galaxy. Here we report the first systematic study of gravitational recoil of equal-mass binaries with equal, but anti-aligned, spins parallel to the orbital

Amit Kashi, Noam Soker

We assume that the helium-I lines emitted by the massive binary system Eta Carinae are formed in the acceleration zone of the less-massive secondary star. We calculate the Doppler shift of the lines as a function of orbital phase and of several parameters of the binary system. We find that a good fit is obtained if the helium lines are formed in the region w

M. W. Krasny, F. Fayette, W. Placzek, A. Siodmok

In this paper we propose a strategy for measuring the inclusive W-boson production processes at LHC. This strategy exploits simultaneously the unique flexibility of the LHC collider in running variable beam particle species at variable beam energies, and the configuration flexibility of the LHC detectors. We propose their concrete settings for a precision me

Vladimir Braverman, Rafail Ostrovsky, Carlo Zaniolo

A streaming model is one where data items arrive over long period of time, either one item at a time or in bursts. Typical tasks include computing various statistics over a sliding window of some fixed time-horizon. What makes the streaming model interesting is that as the time progresses, old items expire and new ones arrive. One of the simplest and central

Jason Fox Manning

We study the variety of actions of a fixed (Chevalley) group on arbitrary geodesic, Gromov hyperbolic spaces. In high rank we obtain a complete classification. In rank one, we obtain some partial results and give a conjectural picture.

Mikhail Khovanov, Volodymyr Mazorchuk, Catharina Stroppel

This article contains a review of categorifications of semisimple representations of various rings via abelian categories and exact endofunctors on them. A simple definition of an abelian categorification is presented and illustrated with several examples, including categorifications of various representations of the symmetric group and its Hecke algebra via

Ofer Aharony, Zohar Komargodski, Assaf Patir

We discuss the moduli space of nine dimensional N=1 supersymmetric compactifications of M theory / string theory with reduced rank (rank 10 or rank 2), exhibiting how all the different theories (including M theory compactified on a Klein bottle and on a Mobius strip, the Dabholkar-Park background, CHL strings and asymmetric orbifolds of type II strings on a

Fumio Hiai, Takuho Miyamoto, Yoshimichi Ueda

Motivated by Voiculescu&#39;s liberation theory, we introduce the orbital free entropy $χ_orb$ for non-commutative self-adjoint random variables (also for &#34;hyperfinite random multi-variables&#34;). Besides its basic properties the relation of $χ_orb$ with the usual free entropy $χ$ is shown. Moreover, the dimension counterpart $δ_{0,orb}$ of $χ_orb$ is d

Martin Dyer, Leslie Ann Goldberg, Mark Jerrum

We give a systematic development of the application of matrix norms to rapid mixing in spin systems. We show that rapid mixing of both random update Glauber dynamics and systematic scan Glauber dynamics occurs if any matrix norm of the associated dependency matrix is less than 1. We give improved analysis for the case in which the diagonal of the dependency

M. Hirai, S. Kumano, T. -H. Nagai, K. Sudoh

Fragmentation functions and their uncertainties are determined for pion, kaon, and proton by a global $χ^2$ analysis of charged-hadron production data in electron-positron annihilation and by the Hessian method for error estimation. It is especially important that the uncertainties of the fragmentation functions are estimated in this analysis. The results in

Gershon Wolansky

Given a probability measure $μ$ on the $n-$torus $T^n$ and a rotation vector $k\in R^n$, we ask wether there exists a minimizer to the integral $\int_{T^n} |\gradϕ+k|^2 dμ$. This problem leads, naturally, to a class of elliptic PDE and to an optimal transportation (Monge-Kantorovich) class of problems on the torus. It is also related to higher dimensional Au

Nikodem J. Poplawski

The purely affine Lagrangian for linear electrodynamics, that has the form of the Maxwell Lagrangian in which the metric tensor is replaced by the symmetrized Ricci tensor and the electromagnetic field tensor by the tensor of homothetic curvature, is dynamically equivalent to the Einstein-Maxwell equations in the metric-affine and metric formulation. We show

Tatsuma Nishioka, Tadashi Takayanagi

It has been known that the Bekenstein-Hawking entropy of the black hole in AdS_5 * S^5 agrees with the free N=4 super Yang-Mills entropy up to the famous factor 4/3. This factor can be interpreted as the ratio of the entropy of the free Yang-Mills to the entropy of the strongly coupled Yang-Mills. In this paper we compute this factor for infinitely many N=1

Yookyung Noh, Jounghun Lee

We explore the evolution of the large-scale anisotropy in the velocity field caused by the gravitational pancaking effect assuming a LCDM universe. The Millennium Run halo catalogs at four different redshifts, z=0, 0.5, 1 and z=2 are analyzed to find that the pancaking effect starts to intervene the hierarchical structure formation at redshift z=2 when a cha

Wen-Ching Winnie Li, Yotsanan Meemark

In this paper, we study the Drinfeld cusp forms for $Γ_1(T)$ and $Γ(T)$ using Teitelbaum&#39;s interpretation as harmonic cocycles. We obtain explicit eigenvalues of Hecke operators associated to degree one prime ideals acting on the cusp forms for $Γ_1(T)$ of small weights and conclude that these Hecke operators are simultaneously diagonalizable. We also sh

Yongseok Oh, Wei Liu, C. M. Ko

We reinvestigate the $J/ψ$ dissociation processes induced by the reactions with nucleons, $J/ψ+ N \to \bar{D}^{(*)} + Λ_c$, in the meson-exchange model. Main constraints used in this work are vector-meson dominance and charm vector-current conservation. We show that the cross section for $J/ψ+ N \to \bar{D} + Λ_c$ can be larger than that for $J/ψ+ N \to \bar

Luca Fabrizio Di Cerbo

In this article we give a brief survey of breather and soliton solutions to the Ricci flow and prove a no breather and soliton theorem for homogeneous solutions.

Michael Politano, Kevin P. Weiler

We perform population synthesis calculations of present-day post common envelope binaries (PCEBs) and zero-age cataclysmic variables (ZACVs) using a common envelope efficiency parameter, alphaCE, that is a function of secondary mass, Ms. We investigate three basic possibilities: (1) a standard constant alphaCE prescription, with alphaCE = 1.0, 0.6, 0.3, 0.2,

M S Hansen, F Faure, B I Zhilinskii

We present a 1-parameter family of systems with fractional monodromy and adiabatic separation of motion. We relate the presence of monodromy to a redistribution of states both in the quantum and semi-quantum spectrum. We show how the fractional monodromy arises from the non diagonal action of the dynamical symmetry of the system and manifests itself as a gen

Xi Wang, Ali Shakouri, Bin Yu, Xuhui Sun

The observation of pure phonon confinement effect in germanium nanowires is limited due to the illumination sensitivity of Raman spectra. In this paper we measured Raman spectra for different size germanium nanowires with different excitation laser powers and wavelengths. By eliminating the local heating effect, the phonon confinement effect for small size n

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

The proposed analysis of the currently available experimental results concerning the neural cell activity in the brain area known as hippocampus suggests a particular mechanism of spatial information and memory processing. Below it is argued that the spatial information available through the analysis of the hippocampal cell activity is predominantly of topol

David H. Foster, Jens U. Noeckel, Andrew K. Coook

We demonstrate numerically calculated electromagnetic eigenmodes of a 3D dome cavity resonator that owe their shape and character entirely to the Goos-Haenchen effect. The V-shaped modes, which have purely TE or TM polarization, are well described by a 2D billiard map with the Goos-Haenchen shift included. A phase space plot of this augmented billiard map re

Sachin Goyal, Noel C. Perkins

Cables under very low tension may become highly contorted and form loops, tangles, knots and kinks. These nonlinear deformations, which are dominated by flexure and torsion, pose serious concerns for cable deployment. Simulation of the three-dimensional nonlinear dynamics of loop and tangle formation requires a 12th order rod model and the computational effo

Gunnar Nordström

This is the third paper by Nordstr{ö}m on his five dimensional theory. Here Nordstr{ö}m attempts to base a theory of matter on the energy conservation generalized to the five dimensional case. This involves a new fundamental constant related to the elementary electric charge.

Gunnar Nordström

This is the second paper by Nordstr{ö}m on his five dimensional theory. It aims at generalizing the relations $\mathbf{D} = ε\mathbf{E}$, $\mathbf{B} = μ\mathbf{H}$ of electromagnetism to the five dimensional gravito-electric theory and to show that this is consistent with the principle of equivalence. Some steps are taken toward providing a foundation for a

Gunnar Nordström

This is the first paper by Gunnar Nordstr{ö}m (1881--1923) on his five dimensional theory. In his summary he states: &#39;&#39;It is shown, that a unifying treatment of the electromagnetic and gravitational fields is possible, if one considers the four dimensional spacetime world to be a surface in a five dimensional world.&#39;&#39; This paper was followed

Vinod Krishna

This work identifies geometric effects on dynamics due to nonadiabatic couplings in Born Oppenheimer systems and provides a systematic method for deriving corrections to mixed quantum-classical methods. Specifically, an exact path integral formulation of the quantum nonadiabatic dynamics of Born Oppenheimer systems is described. Stationary phase approximatio

P. Achenbach, C. Ayerbe Gayoso, J. Bernauer, R. Böhm

One contribution to the time resolution of a scintillation detector is the signal time spread due to path length variations of the detected photons from a point source. In an experimental study a rectangular scintillator was excited by means of a fast pulsed ultraviolet laser at different positions along its longitudinal axis. Timing measurements with a phot

A. Marinov, I. Rodushkin, A. Pape, Y. Kashiv

Evidence for the existence of long-lived isotopes with atomic mass numbers 261 and 265 and abundance of (1-10)x10$^{-10}$ relative to Au has been found in a study of natural Au using an inductively coupled plasma - sector field mass spectrometer. The measured masses fit the predictions made for the masses of $^{261}$Rg and $^{265}$Rg (Z=111) and for some iso

Roy H. Goodman, Richard Haberman

We present a new and complete analysis of the n-bounce resonance and chaotic scattering in solitary wave collisions. In these phenomena, the speed at which a wave exits a collision depends in a complicated fractal way on its input speed. We present a new asymptotic analysis of collective-coordinate ODEs, reduced models that reproduce the dynamics of these sy

Alan T. Huckleberry, Marek Kus, Patrick Schuetzdeller

We investigate the parameter dynamics of eigenvalues of Hamiltonians (&#39;level dynamics&#39;) defined on symmetric spaces relevant for condensed matter and particle physics. In particular we: 1) identify appropriate reduced manifold on which the motion takes place, 2) identify the correct Poisson structure ensuring the Hamiltonian character of the reduced

Filippo Viviani

In this expository paper, we first review the classification of the restricted simple Lie algebras in characteristic different from 2 and 3 and then we describe their infinitesimal deformations. We conclude by indicating some possible application to the deformations of simple finite group schemes.

Mark C. Wilson

In 1986 S. Sattolo introduced a simple algorithm for uniform random generation of cyclic permutations on a fixed number of symbols. This algorithm is very similar to the standard method for generating a random permutation, but is less well known. We consider both methods in a unified way, and discuss their relation with exhaustive generation methods. We anal

Geoffrey Pritchard, Mark C. Wilson

We consider the problem of manipulation of elections using positional voting rules under Impartial Culture voter behaviour. We consider both the logical possibility of coalitional manipulation, and the number of voters that must be recruited to form a manipulating coalition. It is shown that the manipulation problem may be well approximated by a very simple

Romain Tessera

We introduce a notion of &#34;gradient at a given scale&#34; of functions defined on a metric measure space. We then use it to define Sobolev inequalities at large scale and we prove their invariance under large-scale equivalence (maps that generalize the quasi-isometries). We prove that for a Riemmanian manifold satisfying a local Poincare inequality, our n

J. Lucas M. Barbosa, Jorge H. S. de Lira, Vladimir Oliker

Let $ψ$ be a given function defined on a Riemannian space. Under what conditions does there exist a compact starshaped hypersurface $M$ for which $ψ$, when evaluated on $M$, coincides with the $m-$th elementary symmetric function of principal curvatures of $M$ for a given $m$? The corresponding existence and uniqueness problems in Euclidean space have been i

Assaf Hasson, Alf Onshuus, Ya&#39;acov Peterzil

We prove the Zil&#39;ber Trichotomy Principle for all 1-dimensional structures which are definable in o-minimal ones. In particular, we show that any stable 1-dimensional structure is necessarily locally modular. The main tool is a theory for intersection of curves which we develop.

Wilfrid Gangbo, Vladimir Oliker

In this paper, we consider probability measures $μ$ and $ν$ on a $d$--dimensional sphere in $\Rd, d \geq 1,$ and cost functions of the form $c(\x,\y)=l(\frac{|\x-\y|^2}{2})$ that generalize those arising in geometric optics where $l(t)=-\log t.$ We prove that if $μ$ and $ν$ vanish on $(d-1)$--rectifiable sets, if $|l&#39;(t)|>0,$ $\lim_{t\to 0^+}l(t)=+\infty

Luca Fabrizio Di Cerbo

We derive, under a technical assumption, the first variation formula for the eigenvalues of the Laplacian on a closed manifold evolving by the Ricci flow and give some applications.

Keqin Liu

We prove the extended Hilbert&#39;s Nullstellensatz in the context of Hu-Liu polynomial trirings.

Miklos Abert, Yair Glasner

Let T be a k-regular tree (k>2) and A its automorphism group. We analyze a generic finitely generated subgroup Gamma of A. We show that Gamma is free and establish a trichotomy on the closure of Gamma: it is either discrete, compact or has index at most 2 in A.

Stefan Kunis, Holger Rauhut

We investigate the problem of reconstructing sparse multivariate trigonometric polynomials from few randomly taken samples by Basis Pursuit and greedy algorithms such as Orthogonal Matching Pursuit (OMP) and Thresholding. While recovery by Basis Pursuit has recently been studied by several authors, we provide theoretical results on the success probability of

Harold Blas

The solitons and kinks of the SU(3) generalized sine-Gordon model (GSG) are shown to describe the baryonic spectrum of two-dimensional quantum chromodynamics (QCD$_{2}$). The GSG model arises in the low-energy effective action of bosonized QCD$_{2}$ with unequal quark mass parameters. The GSG potential for $N_{f}=3$ flavors resembles the potential of the eff

Hai-Yang Cheng

Theoretical uncertainties with the time-dependent CP asymmetries $ΔS$ and $A_{\rm CP}$ in $B^0\to K^+K^-K_S$, $K_SK_SK_S$ and $K_Sπ^0π^0$ decays are discussed. In order to have a reliable estimate of CP asymmetries, it is very crucial to understand the underlying mechanism for the nonresonant background which dominates the KKK modes.

Matthew D. Duez, Lawrence E. Kidder, Saul A. Teukolsky

We present a new code for solving the coupled Einstein-hydrodynamics equations to evolve relativistic, self-gravitating fluids. The Einstein field equations are solved on one grid using pseudospectral methods, while the fluids are evolved on another grid by finite differencing. We discuss implementation details, such as the communication between the grids an

Robert M. Gray, Takeshi Hashimoto

Source coding theorems and Shannon rate-distortion functions were studied for the discrete-time Wiener process by Berger and generalized to nonstationary Gaussian autoregressive processes by Gray and by Hashimoto and Arimoto. Hashimoto and Arimoto provided an example apparently contradicting the methods used in Gray, implied that Gray&#39;s rate-distortion e

Roderick V. N. Melnik

In this paper we analyze mathematically how human factors can be effectively incorporated into the analysis and control of complex systems. As an example, we focus our discussion around one of the key problems in the Intelligent Transportation Systems (ITS) theory and practice, the problem of speed control, considered here as a decision making process with l

Roderick V. N. Melnik

In this paper, a general framework for the analysis of a connection between the training of artificial neural networks via the dynamics of Markov chains and the approximation of conservation law equations is proposed. This framework allows us to demonstrate an intrinsic link between microscopic and macroscopic models for evolution via the concept of perturbe

Weiyu Xu, Babak Hassibi

Since the classical work of Berlekamp, McEliece and van Tilborg, it is well known that the problem of exact maximum-likelihood (ML) decoding of general linear codes is NP-hard. In this paper, we show that exact ML decoding of a classs of asymptotically good error correcting codes--expander codes, a special case of low density parity check (LDPC) codes--over

Weiyu Xu

We address the problem,`Is a local tree structure sufficient for the local optimality of message passing algorithm in low density parity check codes?&#39;.It is shown that the answer is negative. Using this observation, we pinpoint a flaw in the proof of Theorem 1 in the paper `The Capacity of Low-Density Parity-Check Codes Under Message-Passing Decoding&#39

S. H. W. van der Ploeg, A. Izmalkov, M. Grajcar, U. Huebner

Controllable adiabatic evolution of a multi-qubit system can be used for adiabatic quantum computation (AQC). This evolution ends at a configuration where the Hamiltonian of the system encodes the solution of the problem to be solved. As a first steps towards realization of AQC we have investigated two, three and four flux qubit systems. These systems were c

I. A. Fomin

Effect of the &#34;random anisotropy&#34; type disorder on orientation of the magnetization in an amorphous magnet is considered. It is shown, that the principal corrections to the free energy of the magnet originate from the fluctuations of the order parameter in the direction of its degeneracy. The types of disorder are found, which lift the continuous deg

J. Kroha, S. Kirchner, G. Sellier, P. W&#34;olfle

We consider Kondo impurity systems with multiple local orbitals, such as rare earth ions in a metallic host or multi--level quantum dots coupled to metallic leads. It is shown that the multiplet structure of the local orbitals leads to multiple Kondo peaks above the Fermi energy $E_F$, and to ``shadow&#39;&#39; peaks below $E_F$. We use a slave boson mean fi

Roderick V. N. Melnik, Roy Mahapatra

We demonstrate that the conventional application of linear models to the analysis of optoelectromechanical properties of nanostructures in bandstructure engineering could be inadequate. The focus of the present paper is on a model based on the coupled Schrodinger-Poisson system where we account consistently for the piezoelectric effect and analyze the influe

Zhixin Qian, Viraht Sahni

In local effective potential theories of electronic structure, the electron correlations due to the Pauli exclusion principle, Coulomb repulsion, and correlation-kinetic effects, are all incorporated in the local electron-interaction potential $v_{ee}({\bf r})$. In previous work, it has been shown that for spherically symmetric or sphericalized systems, the

Brandon C. Wood, Nicola Marzari

We present a detailed study of proton dynamics in the hydrogen-bonded superprotonic conductor CsHSO4 from first-principles molecular dynamics simulations, isolating the subtle interplay between the dynamics of the O--H chemical bonds, the O...H hydrogen bonds, and the SO4 tetrahedra in promoting proton diffusion. We find that the Grotthus mechanism of proton

A. Rebei, J. Hohlfeld

The interaction of polarized light with a spin in the presence of dissipation is shown to be equivalent to a spin transfer process that can cause switching. In plasmas, the spin transfer is dominated by a spin-spin exchange term while at lower energy densities it is dominated by an optical Barnett-like effect. This latter effect is used in conjunction with o

Alexander Tselev, Steven M. Anlage, Zhengkun Ma, John Melngailis

We demonstrate that a near-field microwave microscope based on a transmission line resonator allows imaging in a substantially wide range of frequencies, so that the microscope properties approach those of a spatially-resolved impedance analyzer. In the case of an electric probe, the broadband imaging can be used in a direct fashion to separate contributions

R. K. Thakur

The possibility of the existence of quark stars has been discussed by several authors since 1970. Recently, it has been pointed out that two putative neutron stars, RXJ 1856.5 - 3754 in Corona Australis and 3C58 in Cassiopeia are too small and too dense to be neutron stars; they show evidence of being quark stars. Apart from these two objects, there are seve

A. Weiss, D. Downes, R. Neri, F. Walter

We report the detection of the CO 4-3, 6-5, 9-8, 10-9, and 11-10 lines in the Broad Absorption Line quasar APM08279+5255 at z=3.9 using the IRAM 30m telescope. We also present IRAM PdBI high spatial resolution observations of the CO 4-3 and 9-8 lines, and of the 1.4mm dust radiation as well as an improved spectrum of the HCN(5-4) line. Unlike CO in other QSO

Alwyn Wootten

The Atacama Large Millimeter/submillimeter Array (ALMA) combines large collecting area and location on a high dry site to provide it with unparalleled potential for sensitive millimeter/submillimeter spectral line observations. Its wide frequency coverage, superb receivers and flexible spectrometer will ensure that its potential is met. Since the 1999 meetin

V. A. Korol, M. G. Kozlov

We calculate isotope mass shift for several light ions using Dirac wave functions and mass shift operator with relativistic corrections of the order of $(αZ)^2$. Calculated relativistic corrections to the specific mass shift vary from a fraction of a percent for Carbon, to 2% for Magnesium. Relativistic corrections to the normal mass shift are typically smal