April 2007 arXiv papers — page 5

Paul Lasky, Anthony Lun

We utilize a recent formulation of a spherically symmetric spacetime endowed with a general decomposition of the energy momentum tensor [Phys. Rev. D, 75, 024031 (2007)] to derive equations governing spherically symmetric distributions of electromagnetic matter. We show the system reduces to the Reissner-Nordstrom spacetime in general, spherically symmetric

R. Valdés Aguilar, A. B. Sushkov, C. L. Zhang, Y. J. Choi

We report the spectra of magnetically induced electric dipole absorption in Eu$_{0.75}$Y$_{0.25}$MnO$_3$ from temperature dependent far infrared spectroscopy (10-250 cm$^{-1}$). These spectra, which occur only in the $e||a$ polarization, consist of two relatively narrow electromagnon features that onset at $T_{FE}=30$ K and a broad absorption band that persi

M. Stewart Siu

We introduce the idea of using adiabatic rotation to generate superpositions of a large class of quantum states. For quantum computing this is an interesting alternative to the well-studied "straight line" adiabatic evolution. In ways that complement recent results, we show how to efficiently prepare three types of states: Kitaev's toric code sta

Alastair Craw

We give a new moduli construction of the minimal resolution of the singularity of type 1/r(1,a) by introducing the Special McKay quiver. To demonstrate that our construction trumps that of the G-Hilbert scheme, we show that the induced tautological line bundles freely generate the bounded derived category of coherent sheaves on X by establishing a suitable d

Mariana Frank, Ismail Turan, Lorric Ziegler

We discuss and compare the effects of one extra dimension in the Randall Sundrum models on the evaluation of the Casimir force between two parallel plates. We impose the condition that the result reproduce the experimental measurements within the known uncertainties in the force and the plate separation, and get an upper bound kR < 20 if the curvature parame

Kenji Fukushima

Color Glass Condensate (CGC) provides a classical description of dense gluon matter at high energies. Using the McLerran-Venugopalan (MV) model we calculate the initial energy density ε(τ) in the early stage of the relativistic nucleus-nucleus collision. Our analytical formula reproduces the quantitative results from lattice discretized simulations and leads

Masato Minamitsuji

We discuss Casimir effect of a massless, minimally coupled scalar field in a 6D warped flux compactification model and its implications for the hierarchy and cosmological constant problems, which are longstanding puzzles in phenomenology and cosmology. Due to the scale invariance of the background theory, the 4D effective theory contains a volume modulus. To

C. Reichhardt, C. J. Olson Reichhardt

We show numerically that in a binary system of Yukawa particles, a dispersity driven disordering transition occurs. In the presence of quenched disorder this disordering transition coincides with a marked increase in the depinning threshold, known as a peak effect. We find that the addition of poorly pinned particles can increase the overall pinning in the s

Paul E. Reimer

The Drell-Yan process is a standard tool for probing the partonic structure of hadrons. Since the process proceeds through a quark-antiquark annihilation, Drell-Yan scattering possesses a unique ability to selectively probe sea distributions. This review examines the application of Drell-Yan scattering to elucidating the flavor asymmetry of the nucleon&#39;s

Samir Salim, R. Michael Rich, Stéphane Charlot, Jarle Brinchmann

We measure star formation rates of ~50,000 optically-selected galaxies in the local universe (z~0.1), spanning a range from gas-rich dwarfs to massive ellipticals. We obtain dust-corrected SFRs by fitting the GALEX (UV) and SDSS (optical) photometry to a library of population synthesis models that include dust attenuation. For star-forming galaxies, our UV-b

M. R. Becker, T. A. McKay, B. Koester, R. H. Wechsler

The distribution of galaxies in position and velocity around the centers of galaxy clusters encodes important information about cluster mass and structure. Using the maxBCG galaxy cluster catalog identified from imaging data obtained in the Sloan Digital Sky Survey, we study the BCG-galaxy velocity correlation function. By modeling its non-Gaussianity, we me

J. R. Williams, L. DiCarlo, C. M. Marcus

We report on the fabrication and transport studies of a single-layer graphene p-n junction. Carrier type and density in two adjacent regions are individually controlled by electrostatic gating using a local top gate and a global back gate. A functionalized Al203 oxide that adheres to graphene and does not significantly affect its electronic properties is des

J. Bloch, A. Frommer, B. Lang, T. Wettig

The overlap Dirac operator in lattice QCD requires the computation of the sign function of a matrix. While this matrix is usually Hermitian, it becomes non-Hermitian in the presence of a quark chemical potential. We show how the action of the sign function of a non-Hermitian matrix on an arbitrary vector can be computed efficiently on large lattices by an it

D. A. Abanin, L. S. Levitov

Recent experimental work on locally gated graphene layers resulting in p-n junctions have revealed quantum Hall effect in their transport behavior. We explain the observed conductance quantization which is fractional in the bipolar regime and integer in the unipolar regime in terms of quantum Hall edge modes propagating along and across the p-n interface. In

Dale Li, Yanqun Dong, R. G. Ramos, J. D. Murray

In spectroscopy, it is conventional to treat pulses much stronger than the linewidth as delta-functions. In NMR, this assumption leads to the prediction that pi pulses do not refocus the dipolar coupling. However, NMR spin echo measurements in dipolar solids defy these conventional expectations when more than one pi pulse is used. Observed effects include a

Cyril Houdayer

In the context of Free Probability Theory, we study two different constructions that provide new examples of factors of type ${\rm II_1}$ with prescribed fundamental group. First we investigate state-preserving group actions on the almost periodic free Araki-Woods factors satisfying both a condition of mixing and a condition of free malleability in the sense

Tapan Naskar, John Ward

We consider the future dynamics of a transient phantom dominated phase of the universe in LQC and in the RS braneworld, which both have a non-standard Friedmann equation. We find that for a certain class of potentials, the Hubble parameter oscillates with simple harmonic motion in the LQC case and therefore avoids any future singularity. For more general pot

Mustafa Sarisaman

We discuss the current conservation laws in sigma models based on a compact Lie groups of the same dimensionality and connected to each other via pseudoduality transformations in two dimensions. We show that pseudoduality transformations induce an infinite number of nonlocal conserved currents on the pseudodual manifold.

Elchanan Mossel, Allan Sly

In this work we show that for every $d < \infty$ and the Ising model defined on $G(n,d/n)$, there exists a $β_d > 0$, such that for all $β< β_d$ with probability going to 1 as $n \to \infty$, the mixing time of the dynamics on $G(n,d/n)$ is polynomial in $n$. Our results are the first polynomial time mixing results proven for a natural model on $G(n,d/n)$ fo

Abhik Kumar Sanyal

The expansion rate of `Intermediate inflation' lies between the exponential and power law expansion but corresponding accelerated expansion does not start at the onset of cosmological evolution. Present study of `Intermediate inflation' reveals that it admits scaling solution and has got a natural exit form it at a later epoch of cosmic evolution, leading to

Allal Ghanmi

A class of generalized complex polynomials of Hermite type, suggested by a special magnetic Schrodinger operator, is introduced and some related basic properties are discussed.

Hans-Joachim Drescher, Adrian Dumitru, Clement Gombeaud, Jean-Yves Ollitrault

We show that the centrality and system-size dependence of elliptic flow measured at RHIC are fully described by a simple model based on eccentricity scaling and incomplete thermalization. We argue that the elliptic flow is at least 25% below the (ideal) ``hydrodynamic limit&#39;&#39;, even for the most central Au-Au collisions. This lack of perfect equilibra

F. M. Souza, S. A. Leao, R. M. Gester, A. P. Jauho

We study spin-polarized transient transport in a quantum dot coupled to two ferromagnetic leads subjected to a rectangular bias voltage pulse. Time-dependent spin-resolved currents, occupations, spin accumulation, and tunneling magnetoresistance (TMR) are calculated using both nonequilibrium Green function and master equation techniques. Both parallel and an

Eyo Eyo Ita

In this paper we derive 4-dimensional General Relativity from three dimensions, using the intrinsic spatial geometry inherent in Yang--Mills theory which has been exposed by previous authors as well as as some properties of the Ashtekar variables. We provide various interesting relations, including the fact that General Relativity can be written as a Yang--M

Roberto Galván-Madrid, Enrique Vázquez-Semadeni, Jongsoo Kim, Javier Ballesteros-Paredes

We present measurements of the mean dense core lifetimes in numerical simulations of magnetically supercritical, turbulent, isothermal molecular clouds, in order to compare with observational determinations. &#34;Prestellar&#34; lifetimes (given as a function of the mean density within the cores, which in turn is determined by the density threshold n_thr use

BABAR Collaboration, B. Aubert

Using 385 fb^-1 of e^+e^- collisions at the CM energies of around 10.6 GeV recorded by the BaBar experiment, we study the amplitudes of the singly Cabibbo-suppressed decay D^0 --> K^- K^+ pi^0. We measure the strong phase difference between the D0bar and D0 decays to the K^*(892)^+ K^- state to be -35.5 +/- 1.9 (stat) +/- 2.2 (syst) degrees, and their amplit

A. V. Kotikov, L. N. Lipatov, A. Rej, M. Staudacher

We prove that the validity of the recently proposed dressed, asymptotic Bethe ansatz for the planar AdS/CFT system is indeed limited at weak coupling by operator wrapping effects. This is done by comparing the Bethe ansatz predictions for the four-loop anomalous dimension of finite-spin twist-two operators to BFKL constraints from high-energy scattering ampl

Hugh Denoncourt, Brant C. Jones

The maximally clustered permutations are characterized by avoiding the classical permutation patterns 3421, 4312, and 4321. This class contains the freely-braided permutations and the fully-commutative permutations. In this work, we show that the generating functions for certain fully-commutative pattern classes can be transformed to give generating function

Thomas Becher, Kirill Melnikov

We obtain a simple relation between massless and massive scattering amplitudes in gauge theories in the limit where all kinematic invariants are large compared to particle masses. We use this relation to derive the two-loop QED corrections to large-angle Bhabha scattering.

Silvia Picozzi, Kunihiko Yamauchi, Biplab Sanyal, Ivan A. Sergienko

Using first principles calculations, we study the microscopic origin of ferroelectricity (FE) induced by magnetic order in the orthorhombic HoMnO3. We obtain the largest ferroelectric polarization observed in the whole class of improper magnetic ferroelectrics to date. We find that the two proposed mechanisms for FE in multiferroics, lattice- and electronic-

Alexander Odesskii

We construct a family of integrable hydrodynamic type systems with three independent and n>1 dependent variables in terms of solutions of linear system of PDEs with rational coefficients. We choose the existence of a pseudopotential as a criterion of integrability. In the case n=2 this family is a general solution of the classification problem for such syste

Thomas G. Rizzo

In an extension of the Standard Model(SM) based on the ideas of Lee and Wick, Grinstein, O&#39;Connell and Wise have found an interesting way to remove the usual quadratically divergent contributions to the Higgs mass induced by radiative corrections. Phenomenologically, the model predicts the existence of Terascale, negative-norm copies of the usual SM fiel

M. L. Plumer

Biquadratic {\it antisymmetric} exchange terms of the form $ - [C_{ij} e^α_{ij}({\bf s}_i\times{\bf s}_j)_z]^2$, where ${\bf e}_{ij}$ is the unit vector connecting sites $i$ and $j$ and $α= x,y$, due partially to magnetoelectric coupling effects, are shown to be responsible for the spin-flop helical phase in CuFeO$_2$ at low magnetic field and temperature. U

Rupert L. Frank, Christian Hainzl, Serguei Naboko, Robert Seiringer

For the BCS equation with local two-body interaction $λV(x)$, we give a rigorous analysis of the asymptotic behavior of the critical temperature as $λ\to 0$. We derive necessary and sufficient conditions on $V(x)$ for the existence of a non-trivial solution for all values of $λ>0$.

Jean Alexandre, Konstantinos Farakos

We quantize scalar fluctuations in 1+1 dimensions above a classical background kink. The properties of the effective action for the corresponding classical field are studied with an exact functional method, alternative to exact Wilsonian renormalization, where the running parameter is a bare mass, and the regulator of the quantum theory is fixed. We extend t

ZEUS Collaboration, S. Chekanov

Charm production in deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 82 pb^{-1}. Charm has been tagged by reconstructing D^{*+}, D^0, D^{+} and D_s^+ (+ c.c.) charm mesons. The charm hadrons were measured in the kinematic range p_T(D^{*+},D^0,D^{+}) > 3 GeV, p_T(D_s^+)>2 GeV and |η(D)| < 1.6 for 1.5

Martin Bays, Boris Zilber

We show that algebraic analogues of universal group covers, surjective group homomorphisms from a $\mathbb{Q}$-vector space to $F^{\times}$ with &#34;standard kernel&#34;, are determined up to isomorphism of the algebraic structure by the characteristic and transcendence degree of $F$ and, in positive characteristic, the restriction of the cover to finite fi

Christian Blum, Willem L. Vos, Vinod Subramaniam

We theoretically discuss how to tune the competition between Forster transfer and spontaneous emission in a continuous and nondestructive fashion. The proposed approach is especially suitable for delicate biological systems like light harvesting complexes and fluorescent protein oligomers. We demonstrate that the manipulation of the density of photonic state

Eliahu Levy

Taking matrix as a synonym for a numerical function on the Cartesian product of two (in general, infinite) sets, a simple purely algebraic &#34;reciprocity property&#34; says that the set of rows spans a finite-dim space iff the set of columns does so. Similar topological reciprocity properties serve to define strongly compact and weakly compact matrices, fe

Simon Moulin

We prove dispersive estimates at low frequency in dimensions n greater or equal to 4 for the wave equation for a very large class of real-valued potentials, provided the zero is neither an eigenvalue nor a resonance.

Diego Conti

We develop a method, initially due to Salamon, to compute the space of ``invariant&#39;&#39; forms on an associated bundle X=P\times_G V, with a suitable notion of invariance. We determine sufficient conditions for this space to be d-closed. We apply our method to the construction of Calabi-Yau metrics on TCP^1 and TCP^2.

Annika Wedemeier, Holger Merlitz, Chen-Xu Wu, Jörg Langowski

In this paper a lattice model for diffusional transport of particles in the interphase cell nucleus is proposed. Dense networks of chromatin fibers are created by three different methods: randomly distributed, non-interconnected obstacles, a random walk chain model, and a self avoiding random walk chain model with persistence length. By comparing a discrete

Thibault Damour, Alessandro Nagar

We update the analytical estimate of the final spin of a coalescing black-hole binary derived within the Effective-One-Body (EOB) approach. We consider unequal-mass non-spinning black-hole binaries. It is found that a more complete account of relevant physical effects (higher post-Newtonian accuracy, ringdown losses) allows the {\it analytical} EOB estimate

S. Banerjee, K. Rajendran, N. Gayathri, M. Sardar

We present in this paper the changes in the room temperature magnetic property of ZnO on Mn doping prepared using solvo-thermal process. The zero field cooled (ZFC) and field cooled (FC) magnetisation of undoped ZnO showed bifurcation and magnetic hysteresis at room temperature. Upon Mn doping the magnetic hysteresis at room temperature and the bifurcation i

R. Bernabei

DAMA is an observatory for rare processes and it is operative deep underground at the Gran Sasso National Laboratory of the I.N.F.N. (LNGS). Here some arguments will be presented on the investigation on dark matter particles by annual modulation signature and on some of the realized double beta decay searches.

A. V. Razumov, Yu. G. Stroganov, P. Zinn-Justin

Integral formulae for polynomial solutions of the quantum Knizhnik-Zamolodchikov equations associated with the R-matrix of the six-vertex model are considered. It is proved that when the deformation parameter q is equal to e^{+- 2 pi i/3} and the number of vertical lines of the lattice is odd, the solution under consideration is an eigenvector of the inhomog

Mingxing Luo, Guohuai Zhu

Fermionic unparticles are introduced and their basic properties are discussed. Some phenomenologies related are exploited, such as their effects on charged Higgs boson decays and anomalous magnetic moments of leptons. Also, it has been found that measurements of $B^0-\bar B^0$ mixing could yield interesting constraints on couplings between unparticle operato

C. Galindo, F. Monserrat

We introduce the concept of $δ$-sequence. A $δ$-sequence $Δ$ generates a well-ordered semigroup $S$ in $\mathbb{Z}^2$ or $\mathbb{R}$. We show how to construct (and compute parameters) for the dual code of any evaluation code associated with a weight function defined by $Δ$ from the polynomial ring in two indeterminates to a semigroup $S$ as above. We prove

M. Danilov, R. Mizuk

The experimental evidence for pentaquarks is reviewed and compared with the experiments that do not see any sign of pentaquarks. This paper is based on a lecture given at the 33rd ITEP Winter School of Physics in the beginning of 2005. Results obtained since then are summarized in the epilogue.

Jung Hoon Kim, Jung Hoon Han

We investigate the influence of the spin-phonon coupling in the triangular antiferromagnet where the coupling is of the exchange-striction type. The magnon dispersion is shown to be modified significantly at wave vector (2pi,0) and its symmetry-related points, exhibiting a roton-like minimum and an eventual instability in the dispersion. Various correlation

Fabio Cipriani, Gabriele Grillo

A suitable notion of hypercontractivity for a nonlinear semigroup $\{T_t\}$ is shown to imply Gagliardo--Nirenberg inequalities for its generator $H$, provided a subhomogeneity property holds for the energy functional $(u,Hu)$. We use this fact to prove that, for semigroups generated by operators of $p$--Laplacian--type, hypercontractivity implies ultracontr

Aimé Lachal, Thomas Simon

Consider the first exit time $T_{a,b}$ from a finite interval $[-a,b]$ for an homogeneous fluctuating functional $X$ of a linear Brownian motion. We show the existence of a finite positive constant $\k$ such that $$\lim_{t\to\infty}t^{-1}\log \p[ T_{ab} > t] = -\k.$$ Following Chung&#39;s original approach, we deduce a &#34;liminf&#34; law of the iterated lo

L. Calibbi, Y. Mambrini, S. K. Vempati

We will consider a SUSY-SU(5) with one right-handed neutrino with a large top like Yukawa coupling. Assuming universal soft masses at high scale we compute the low-energy spectrum and subsequently the neutralino LSP relic density taking also into consideration SU(5) as well as the see-saw running effects above the gauge coupling unification scale. We found t

Maya Chuchem, Doron Cohen

The amount $Q$ of particles that are transported via a path of motion is characterized by its expectation value $<Q>$ and by its variance $Var(Q)$. We analyze what happens if a particle has two optional paths available to get from one site to another site, and in particular what is $Var(Q)$ for the current which is induced in a quantum stirring device. It tu

W. Bednarek

Young open clusters are likely sites of cosmic ray acceleration as indicated by recent detections of the TeV gamma-ray sources in the directions of two open clusters (Cyg OB2 and Westerlund 2) and their directional proximity to some unidentified EGRET sources. In fact, up to now a few different scenarios for acceleration of particles inside open clusters hav

M. T. M. van Kessel

We construct a theory which has the same particle content as softly broken minimal supersymmetric QED (MSQED) and is free of quadratic divergences up to two loops. Also this theory is completely gauge invariant. It appears that MSQED is not at all the only theory without these quadratic divergences. This proves that there exist non supersymmetric theories in

J. Bobroff, S. Hebert, G. Lang, P. Mendels

We present a comparative study of CoO2 layers in the Bi-misfit and NaxCoO2 cobaltates. Co NMR measures the intrinsic susceptibility of the Co layers and is not affected by spurious contributions. At low dopings where room-temperature thermopower (TEP) is large, Curie-Weiss susceptibilities are observed in both materials. But NMR and muSR experiments find nei

Marilena Barnabei, Flavio Bonetti, Matteo Silimbani

We establish a combinatorial connection between the sequence $(i_{n,k})$ counting the involutions on $n$ letters with $k$ descents and the sequence $(a_{n,k})$ enumerating the semistandard Young tableaux on $n$ cells with $k$ symbols. This allows us to show that the sequences $(i_{n,k})$ are not log-concave for some values of $n$, hence answering a conjectur

Jarah Evslin, Chethan Krishnan, Stanislav Kuperstein

We use an argument analogous to that of Kachru, Pearson and Verlinde to argue that cascades in L^{a,b,c} quiver gauge theories always preserve the form of the quiver, and that all gauge groups drop at each step by the number M of fractional branes. In particular, we demonstrate that an NS5-brane that sweeps out the S^3 of the base of L^{a,b,c} destroys M D3-

Satoshi Moriyama, Tomoko Fuse, Tomohiro Yamaguchi, Koji Ishibashi

We investigate the total spin in an individual single-wall carbon nanotube quantum dot with various numbers of electrons in a shell by using the ratio of the saturation currents of the first steps of Coulomb staircases for positive and negative biases. The current ratio reflects the total-spin transition that is increased or decreased when the dot is connect

Alexander E. Dorokhov, Mikhail A. Ivanov

Within the dispersive approach to the amplitude of the rare decay pi0 -> e+e- the nontrivial dynamics is contained only in the subtraction constant. We express this constant, in the leading order in (m_e/Λ)^2 perturbative series, in terms of the inverse moment of the pion transition form factor given in symmetric kinematics. By using the CELLO and CLEO data

TWQCD Collaboration, Ting-Wai Chiu, Tung-Han Hsieh

We determine the masses and decay constants of the pseudoscalar mesons Bs and Bc, and also the masses of the vector mesons Bs^* and Bc^*, in quenched lattice QCD with exact chiral symmetry. For 100 gauge configurations generated with single-plaquette action at beta = 7.2 on the 32^3 x 60 lattice, we compute point-to-point quark propagators for 33 quark masse

Michael Finkelberg, Victor Ginzburg

For any smooth algebraic curve C, Pavel Etingof introduced a `global&#39; Cherednik algebra as a natural deformation of the cross product of the algebra of differential operators on C^n and the symmetric group. We provide a construction of the global Cherednik algebra in terms of quantumn Hamiltonian reduction. We study a category of character D-modules on a

R. Caimmi

Unsustained matter distributions unescapely collapse unless fragmentation and centrifugal or pressure support take place. Starting from the above evidence, supermassive compact objects at the centre of large-mass galaxies are conceived as the end-product of the gravitational collapse of local density maxima around which overdensities are located. At the begi

A. Y. L. Wong, Y. F. Huang, K. S. Cheng

X-ray transients appeared in optically non-active galactic nuclei have been observed in recent years. The most popular model explaining this kind of phenomena is the conventional tidal disruption model. In this model, when a star moves within the tidal radius of a black hole, part of the star materials will fall into the black hole through an accretion disk,

Pengfei Lan, Peixiang Lu, Wei Cao, Yuhua Li

A new method to coherently control the electron dynamics is proposed using a few-cycle laser pulse in combination with a controlling field. It is shown that this method not only broadens the attosecond pulse bandwidth, but also reduces the chirp, then an isolated 80-as pulse is straightforwardly obtained and even shorter pulse is achievable by increasing the

Shu-Yu Hsu

We prove the uniqueness of solutions of the Ricci flow on complete noncompact manifolds with bounded curvatures using the De Turck approach. As a consequence we obtain a correct proof of the existence of solution of the Ricci harmonic flow on complete noncompact manifolds with bounded curvatures.

Masamichi Ishihara

The author studied the growth of the amplitude in a Mathieu-like equation with multiplicative white noise. The approximate value of the exponent at the extremum on parametric resonance regions was obtained theoretically by introducing the width of time interval, and the exponents were calculated numerically by solving the stochastic differential equations by

Anthony Aguirre, Matthew C Johnson, Assaf Shomer

We evaluate the possibility of observable effects arising from collisions between vacuum bubbles in a universe undergoing false-vacuum eternal inflation. Contrary to conventional wisdom, we find that under certain assumptions most positions inside a bubble should have access to a large number of collision events. We calculate the expected number and angular

Kunihito Ioka, Hiroyuki Nakano

Black hole (BH) oscillations known as quasi-normal modes (QNMs) are one of the most important gravitational wave (GW) sources. We propose that higher perturbative order of QNMs, generated by nonlinear gravitational interaction near the BHs, are detectable and worth searching for in observations and simulations of binary BH mergers. We calculate the metric pe

P. Yu. Moshin, J. L. Tomazelli

The non-relativistic limit of the linear wave equation for zero and unity spin bosons of mass $m$ in the Duffin-Kemmer-Petiau representation is investigated by means of a unitary transformation, analogous to the Foldy-Wouthuysen canonical transformation for a relativistic electron. The interacting case is also analyzed, by considering a power series expansio

L. C. Wang, X. L. Huang, X. X. Yi

The Landau-Zener(LZ) transition of a two-level system coupling to spin chains near their critical points is studied in this paper. Two kinds of spin chains, the Ising spin chain and XY spin chain, are considered. We calculate and analyze the effects of system-chain coupling on the LZ transition. A relation between the LZ transition and the critical points of

Jean-Pierre Dedieu, Gregorio Malajovich

We give an upper bound in O(d ^((n+1)/2)) for the number of critical points of a normal random polynomial with degree d and at most n variables. Using the large deviation principle for the spectral value of large random matrices we obtain the bound O(exp(-beta n^2 + (n/2) log (d-1))) (beta is a positive constant independent on n and d) for the number of mini

Roman Werpachowski

We describe a way to approximate the matrix elements of a real power $α$ of a positive (for $α\ge 0$) or non-negative (for $α\in \mathbb{R}$), infinite, bounded, sparse and Hermitian matrix $W$. The approximation uses only a finite part of the matrix $W$.

Filipe Tostevin, Pieter Rein ten Wolde, Martin Howard

Position determination in biological systems is often achieved through protein concentration gradients. Measuring the local concentration of such a protein with a spatially-varying distribution allows the measurement of position within the system. In order for these systems to work effectively, position determination must be robust to noise. Here, we calcula

Han Uitenbroek, Alexandra Tritschler, Thomas Rimmele

We compare the rms contrast in observed speckle reconstructed G-band images with synthetic filtergrams computed from two magneto-hydrodynamic simulation snapshots. The observations consist of 103 bursts of 80 frames each taken at the Dunn Solar Telescope (DST), sampled at twice the diffraction limit of the telescope. The speckle reconstructions account for t

Jinho Baik, Robert Buckingham, Jeffery DiFranco

The Tracy-Widom distribution functions involve integrals of a Painlevé II function starting from positive infinity. In this paper, we express the Tracy-Widom distribution functions in terms of integrals starting from minus infinity. There are two consequences of these new representations. The first is the evaluation of the total integral of the Hastings-McLe

Fulufhelo Vincent Nelwamondo, Tshilidzi Marwala

Many techniques for handling missing data have been proposed in the literature. Most of these techniques are overly complex. This paper explores an imputation technique based on rough set computations. In this paper, characteristic relations are introduced to describe incompletely specified decision tables.It is shown that the basic rough set idea of lower a

Mark Hovey, Keir H. Lockridge

We show that the category of projective modules over a graded commutative ring admits a triangulation with respect to module suspension if and only if the ring is a finite product of graded fields and exterior algebras on one generator over a graded field (with a unit in the appropriate degree). We also classify the ungraded commutative rings for which the c

W. Frank Moore

Let $S$ and $T$ be local rings with common residue field $k$, let $R$ be the fiber product $S \times_k T$, and let $M$ be an $S$-module. The Poincaré series $P^R_M$ of $M$ has been expressed in terms of $P^S_M$, $P^S_k$ and $P^T_k$ by Kostrikin and Shafarevich, and by Dress and Krämer. Here, an explicit minimal resolution, as well as theorems on the structur

John H. Wise, Tom Abel

(Abridged) Galaxies form in hierarchically assembling dark matter halos. With cosmological three dimensional adaptive mesh refinement simulations, we explore in detail the virialization of baryons in the concordance cosmology, including optically thin primordial gas cooling. We focus on early protogalaxies with virial temperatures of 10^4 K and their progeni

Andris Ambainis

We present an O(\sqrt{N}) discrete query quantum algorithm for evaluating balanced binary NAND formulas and an O(N^{{1/2}+O(\frac{1}{\sqrt{\log N}})}) discrete query quantum algorithm for evaluating arbitrary binary NAND formulas.

Alexander D. Hernandez, Arturo Lopez, Daniel Dominguez

In this work we study the ac dissipation of mesoscopic superconductors at microwave frequencies using the time dependent Ginzburg-Landau equations. Our numerical simulations show that the ac dissipation is strongly dependent on the orientation of the ac magnetic field ($h_{ac}$) relative to the dc magnetic field ($H_{dc}$). When $h_{ac}$ is parallel to $H_{d

Luciano da F Costa, Marcus Kaiser, Claus C Hilgetag

The organization of the connectivity between mammalian cortical areas has become a major subject of study, because of its important role in scaffolding the macroscopic aspects of animal behavior and intelligence. In this study we present a computational reconstruction approach to the problem of network organization, by considering the topological and spatial

Tapas Kumar Das

In recent years, strong analogies have been established between the physics of acoustic perturbations in an inhomogeneous dynamical fluid system, and some kinematic features of space-time in general relativity. An effective metric, referred to as the `acoustic metric&#39;, which describes the geometry of the manifold in which acoustic perturbations propagate

Víctor M. Muñoz Marín, Rosa M. González Delgado, Henrique R. Schmitt, Roberto Cid Fernandes

We present an atlas of the central regions of 75 Seyfert galaxies imaged in the near-UV with the Advanced Camera for Surveys of the Hubble Space Telescope at an average resolution of ~10pc. These data complement archival high resolution data from the Space Telescope at optical and near-IR wavelengths, creating an extremely valuable dataset for astronomers wi

Robin Blume-Kohout, Wojciech H. Zurek

We study quantum Darwinism -- the redundant recording of information about a decohering system by its environment -- in zero-temperature quantum Brownian motion. An initially nonlocal quantum state leaves a record whose redundancy increases rapidly with its spatial extent. Significant delocalization (e.g., a Schroedinger&#39;s Cat state) causes high redundan

J. -S. Huang, M. L. N. Ashby, P. Barmby, M. Brodwin

A SST survey in the NOAO Deep-Wide Field in Boötes provides a complete, 8-micron-selected sample of galaxies to a limiting (Vega) magnitude of 13.5. In the 6.88 deg$^2$ field sampled, 79% of the 4867 galaxies have spectroscopic redshifts, allowing an accurate determination of the local (z<0.3) galaxy luminosity function. Stellar and dust emission can be sepa

C. Providencia, D. P. Menezes, L. Brito, Ph. Chomaz

In the present work we take the non relativistic limit of relativistic models and compare the obtained functionals with the usual Skyrme parametrization. Relativistic models with both constant couplings and with density dependent couplings are considered. While some models present very good results already at the lowest order in the density, models with non-

R. A. Scheepmaker, M. R. Haas, M. Gieles, N. Bastian

We use HST/ACS observations of the spiral galaxy M51 in F435W, F555W and F814W to select a large sample of star clusters with accurate effective radius measurements in an area covering the complete disc of M51. We present the dataset and study the radius distribution and relations between radius, colour, arm/interarm region, galactocentric distance, mass and

S. M. Kanbur, C. Ngeow, A. Nanthakumar, R. Stevens

In this paper, we investigate the linearity versus non-linearity of the Large Magellanic Cloud (LMC) Cepheid period-luminosity (P-L) relation using two statistical approaches not previously applied to this problem: the testimator method and the Schwarz Information Criterion (SIC). The testimator method is extended to multiple stages for the first time, shown

A. Korzenev

A first evaluation of the polarized valence quark distribution $Δu_v(x)+Δd_v(x)$ from the COMPASS experiment (CERN/SPS) is presented. The data were collected by COMPASS in the years 2002--2004 using a 160 GeV polarized muon beam scattered off a large polarized $^6$LiD target and cover the range $1< Q^2 < 100$ GeV$^2$ and $0.006<x<0.7$. The analysis is based

PHENIX Collaboration, A. Adare

The PHENIX experiment presents results from the RHIC 2005 run with polarized proton collisions at sqrt(s)=200 GeV, for inclusive \pi^0 production at mid-rapidity. Unpolarized cross section results are given for transverse momenta p_T=0.5 to 20 GeV/c, extending the range of published data to both lower and higher p_T. The cross section is described well for p

B. L. Frye, D. Coe, D. V. Bowen, N. Benitez

We present results of the HST Advanced Camera for Surveys spectroscopic ground-based redshift survey in the field of A1689. We measure 98 redshifts, increasing the number of spectroscopically confirmed objects by sixfold. We present two spectra from this catalog of the Sextet Arcs, images which arise from a strongly-lensed Lyman Break Galaxy (LBG) at a redsh

Lun-Shin Yao, Dan Hughes

Comment on &#34;Time Step Sensitivity of Nonlinear Atmospheric Models: Numerical Convergence, Truncation Error Growth, and Ensemble Design&#34; Teixeira et al.

H1 Collaboration

A search for narrow baryonic resonances decaying into Xi- pi- or Xi- pi+ and their antiparticles is carried out with the H1 detector using deep inelastic scattering events at HERA in the range of negative photon four-momentum transfer squared 2 < Q^2 < 100 GeV^2. No signal is observed for a new baryonic state in the mass range 1600 - 2300 MeV in either the d

W. Vieser, G. Hensler

To examine the evolution of giant molecular clouds in the stream of a hot plasma we performed two-dimensional hydrodynamical simulations that take full account of self-gravity, heating and cooling effects and heat conduction by electrons. We use the thermal conductivity of a fully ionized hydrogen plasma proposed by Spitzer and a saturated heat flux accordin

Marko Aleksic, Peyman Razaghi, Wei Yu

This paper characterizes the capacity of a class of modulo additive noise relay channels, in which the relay observes a corrupted version of the noise and has a separate channel to the destination. The capacity is shown to be strictly below the cut-set bound in general and achievable using a quantize-and-forward strategy at the relay. This result confirms a

C. Male, G. Le Caer, R. Delannay

A time series delta(n), the fluctuation of the nth unfolded eigenvalue was recently characterized for the classical Gaussian ensembles of NxN random matrices (GOE, GUE, GSE). It is investigated here for the beta-Hermite ensemble as a function of beta (zero or positive) by Monte Carlo simulations. The fluctuation of delta(n) and the autocorrelation function v

L. A. Willson

Mass loss rate formulae are derived from observations or from suites of models. For theoretical models, the following have all been identified as factors greatly influencing the atmospheric structure and mass loss rates: Pulsation with piston amplitude scaling appropriately with stellar L; dust nucleation and growth, with radiation pressure and grain-gas int