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November 2008 arXiv papers — page 33

Showing 3,2013,300 of 4,899 papers

  1. Tsuguhiko Asakawa, Masashi Mori, Satoshi Watamura

    In a previous paper, we investigated the Hopf algebra structure in string theory and gave a unified formulation of the quantization of the string and the space-time symmetry. In this paper, this formulation is applied to the case with a nonzero B-field background, and the twist of the Poincare symmetry is studied. The Drinfeld twist accompanied by the B-fiel

  2. Dong-han Yeom, Heeseung Zoe

    Recently, there have been discussions that black hole complementarity is inconsistent and that the firewall is required to prohibit the observation of duplicated information. It is thought that if the Horowitz-Maldacena proposal works as a selection principle, then this may be an alternative to the firewall. In this paper, we first point out that the Horowit

  3. Thomas Butler, David Reynolds

    The existence of beyond mean field quasi-cycle oscillations in a simple spatial model of predator prey interactions is derived from a path integral formalism. The results agree substantially with those obtained from analysis of similar models using system size expansions of the master equation. In all of these analyses, the discrete nature of predator prey p

  4. Zoran S. Popović, Sashi Satpathy, Richard M. Martin

    Transport measurements of the two-dimensional electron gas (2DEG) at the LaAlO$_3$/SrTiO$_3$ interface have found a density of carriers much lower than expected from the "polar catastrophe" arguments. From a detail density-functional study, we suggest how this discrepancy may be reconciled. We find that electrons occupy multiple subbands at the inter

  5. Yusuke Nishida

    We investigate a two-species Fermi gas with a large mass ratio interacting by an interspecies short-range interaction. Using the Born-Oppenheimer approximation, we determine the interaction energy of two heavy fermions immersed in the Fermi sea of light fermions as a function of the s-wave scattering length. In the BCS limit, we recover the perturbative calc

  6. Paul J. Steinhardt, Daniel Wesley

    We consider how accelerated expansion, whether due to inflation or dark energy, imposes strong constraints on fundamental theories obtained by compactification from higher dimensions. For theories that obey the null energy condition (NEC), we find that inflationary cosmology is impossible for a wide range of compactifications; and a dark energy phase consist

  7. T. M. McQueen, Q. Huang, V. Ksenofontov, C. Felser

    The recently discovered iron arsenide superconductors, which display superconducting transition temperatures as high as 55 K, appear to share a number of general features with high-Tc cuprates, including proximity to a magnetically ordered state and robustness of the superconductivity in the presence of disorder. Here we show that superconductivity in Fe1+dS

  8. Jennifer Burke, Qi S. Zhang

    We obtain a pointwise, a priori bound for the vorticity of axis symmetric solutions to the 3 dimensional Navier-Stokes equations. The bound is in the form of a reciprocal of a power of the distance to the axis of symmetry. This seems to be the first general pointwise estimate established for the axis symmetric Navier-Stokes equations.

  9. Nataliya V. Malyshkina, Fred L. Mannering, Andrew P. Tarko

    In this paper, two-state Markov switching models are proposed to study accident frequencies. These models assume that there are two unobserved states of roadway safety, and that roadway entities (roadway segments) can switch between these states over time. The states are distinct, in the sense that in the different states accident frequencies are generated b

  10. A. Yu. Olshanskii, M. V. Sapir

    A $k$-free like group is a $k$-generated group $G$ with a sequence of $k$-element generating sets $Z_n$ such that the girth of $G$ relative to $Z_n$ is unbounded and the Cheeger constant of $G$ relative to $Z_n$ is bounded away from 0. By a recent result of Benjamini-Nachmias-Peres, this implies that the critical bond percolation probability of the Cayley gr

  11. Z. Li, R. V. Krems

    We present a formalism for rigorous calculations of cross sections for inelastic and reactive collisions of ultracold atoms and molecules confined by laser fields in quasi-2D geometry. Our results show that the elastic-to-inelastic ratios of collision cross sections are enhanced in the presence of a laser confinement and that the threshold energy dependence

  12. Prateek Agrawal, Ethan M. Dolle, Christopher A. Krenke

    One of the simplest extensions of the Standard Model that explains the observed abundance of dark matter is the inert doublet model. In this theory a discrete symmetry ensures that the neutral component of an additional electroweak doublet scalar is stable, and constitutes a dark matter candidate. As massive bodies such as the Sun and Earth move through the

  13. K Manouchehri, J. B. Wang

    Advances in recent years have made it possible to explore quantum dots as a viable technology for scalable quantum information processing. Charge qubits for example can be realized in the lowest bound states of coupled quantum dots and the precision control of the confinement potential allows for the realization of a full set of universal qubit gates, includ

  14. Florent Jouve

    Applying E. Kowalski's recent generalization of the large sieve we prove that certain properties expected to be typical (irreducibility of the characteristic polynomial, absence of squares among the matrix coefficients...) are indeed verified by most (in a very explicit sense) of the elements of GL(n,A) with fixed determinant (where A is an intermediate

  15. Sanjib S. Gupta, Toshihiko Kawano, Peter Möller

    In our calculation of neutron star crust heating we include several key new model features. In earlier work electron capture (EC) only allowed neutron emission from the daughter ground-state; here we calculate, in a deformed QRPA model, EC decay rates to all states in the daughter that are allowed by Gamow-Teller selection rules and energetics. The subsequen

  16. Huan Xu, Constantine Caramanis, Shie Mannor

    Lasso, or $\ell^1$ regularized least squares, has been explored extensively for its remarkable sparsity properties. It is shown in this paper that the solution to Lasso, in addition to its sparsity, has robustness properties: it is the solution to a robust optimization problem. This has two important consequences. First, robustness provides a connection of t

  17. David Easdown, Mark Sapir, Michael Volkov

    We show that every periodic element of the free idempotent generated semigroup on an arbitrary biordered set belongs to a subgroup of the semigroup.

  18. Paul Nunez, Marek Nowakowski

    When rotation is not taken into account, the measurement of the Gravitational Redshift can provide unique information about the compactness ($M/R$) of the star. Rotation alters the gravitational redshift rendering thereby a unique determination of the compactness parameter impossible. Nevertheless, it can be shown that by using some theoretical input, useful

  19. Jan Pruess, Gieri Simonett, Rico Zacher

    We show convergence of solutions to equilibria for quasilinear and fully nonlinear parabolic evolution equations in situations where the set of equilibria is non-discrete, but forms a finite-dimensional $C^1$-manifold which is normally stable.

  20. A. Greilich, S. Spatzek, I. A. Yugova, I. A. Akimov

    We show that the spins of all electrons, each confined in a quantum dot of an (In,Ga)As/GaAs dot ensemble, can be driven into a single mode of precession about a magnetic field. This regime is achieved by allowing only a single mode within the electron spin precession spectrum of the ensemble to be synchronized with a train of periodic optical excitation pul

  21. Kentaro Somiya

    Thermal noise of a mirror is one of the most important issues in high precision measurements such as gravitational-wave detection or cold damping experiments. It has been pointed out that thermal noise of a mirror with multi-layer coatings can be reduced by mechanical separation of the layers. In this paper, we introduce a way to further reduce thermal noise

  22. M. Deka, T. Streuer, T. Doi, S. J. Dong

    We extend the study of lowest moments, $<x>$ and $<x^2>$, of the parton distribution function of the nucleon to include those of the sea quarks; this entails a disconnected insertion calculation in lattice QCD. This is carried out on a $16^3 \times 24$ quenched lattice with Wilson fermion. The quark loops are calculated with $Z_2$ noise vectors and unbiased

  23. Lucianne M. Walkowicz, Suzanne L. Hawley

    We report on our observing program to capture simultaneous spectra of Ca II and Balmer lines in a sample of nearby M3 dwarfs. Our goal is to investigate the chromospheric temperature structure required to produce these lines at the observed levels. We find a strong positive correlation between instantaneous measurements of Ca II K and the Balmer lines in act

  24. S. Feltzing, T. Bensby

    The study of the Milky Way stellar discs in the context of galaxy formation is discussed. In particular we explore the properties of the Milky Way disc using a new sample of about 550 dwarf stars for which we have recently obtained elemental abundances and ages based on high resolution spectroscopy. For all the stars we also have full kinematic information a

  25. Daniel J. B. Smith, Matt J. Jarvis, Chris Simpson, Alejo Martinez-Sansigre

    We announce the discovery of an extended emission line region associated with a high redshift type-2 QSO. The halo, which was discovered in our new wide-field narrow-band survey, resides at z = 2.85 in the Spitzer First Look Survey region and is extended over ~80 kpc. Deep VLBI observations imply that approximately 50 per cent of the radio emission is extend

  26. Jacob Linder, Asle Sudbø

    We construct a theory for low-energy quantum transport in normal$\mid$superconductor junctions involving the recently discovered iron-based high-$T_c$ superconductors. We properly take into account both Andreev bound surface states and the complex Fermi surface topology in our approach, and investigate the signatures of the possible order parameter symmetrie

  27. Orly Gnat, Amiel Sternberg

    In this paper we present computations of the integrated metal-ion column densities produced in the post-shock cooling layers behind fast, radiative shock-waves. For this purpose, we have constructed a new shock code that calculates the non-equilibrium ionization and cooling; follows the radiative transfer of the shock self-radiation through the post-shock co

  28. V. Karas, O. Kopacek

    Magnetic layers are narrow regions where the field direction changes sharply. They often occur in the association with neutral points of the magnetic field. We show that an organised field can produce these structures near a rotating black hole, and we identify them as potential sites of magnetic reconnection. To that end we study the field lines affected by

  29. T. Banakh, M. Vovk, M. R. Wojcik

    We construct an example of a real-valued continuous non-constant function $f$ defined on a connected complete metric space $X$ such that every point of $X$ is a point of local minimum or local maximum for $f$. The space $X$ is connected but fails to be separably connected.

  30. Satish Babu Korada, Eren Sasoglu

    A generalization of Arıkan&#39;s polar code construction using transformations of the form $G^{\otimes n}$ where $G$ is an $\ell \times \ell$ matrix is considered. Necessary and sufficient conditions are given for these transformations to ensure channel polarization. It is shown that a large class of such transformations polarize symmetric binary-input memor

  31. Nick Laskin

    A path integral approach to quantum physics has been developed. Fractional path integrals over the paths of the Lévy flights are defined. It is shown that if the fractality of the Brownian trajectories leads to standard quantum and statistical mechanics, then the fractality of the Lévy paths leads to fractional quantum mechanics and fractional statistical me

  32. Anna N. Morozovska, Eugene A. Eliseev, Sergei V. Svechnikov, Peter Maksymovych

    Thermodynamics of tip-induced nanodomain formation in scanning probe microscopy of ferroelectric films and crystals is studied using the Landau-Ginzburg-Devonshire phenomenological approach. The local redistribution of polarization induced by the biased probe apex is analyzed including the effects of polarization gradients, field dependence of dielectric pro

  33. N. Ni, M. E. Tillman, J. -Q. Yan, A. Kracher

    Single crystalline samples of Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ with $x < 0.12$ have been grown and characterized via microscopic, thermodynamic and transport measurements. With increasing Co substitution, the thermodynamic and transport signatures of the structural (high temperature tetragonal to low temperature orthorhombic) and magnetic (high temperature non

  34. Richard W. Kenyon, David B. Wilson

    A grove is a spanning forest of a planar graph in which every component tree contains at least one of a special subset of vertices on the outer face called nodes. For the natural probability measure on groves, we compute various connection probabilities for the nodes in a random grove. In particular, for &#34;tripartite&#34; pairings of the nodes, the probab

  35. Murray Peshkin

    It has been suggested that the reported temporal oscillations in the weak decay of H-like ions circulating in the GSI storage ring may be accounted for by interference between two different momentum components of the wave function of the parent ions. In that model, the interference is said to come about through coupling of those two momentum components to th

  36. M. I. Ostrovskii

    A necessary and sufficient condition for existence of a Banach space with a finite dimensional decomposition but without the $π$-property in terms of norms of compositions of projections is found.

  37. Zhaohuan Zhu, Lee Hartmann, Charles Gammie

    Observations indicate that mass accretion rates onto low-mass protostars are generally lower than the rates of infall to their disks; this suggests that much of the protostellar mass must be accreted during rare, short outbursts of rapid accretion. We explore when protostellar disk accretion is likely to be highly variable. While constant $α$ disks can in pr

  38. J. J. Honrubia, J. Meyer-ter-Vehn

    We present hybrid PIC simulations of fast electron transport and energy deposition in pre-compressed fusion targets, taking full account of collective magnetic effects and the hydrodynamic response of the background plasma. Results on actual ignition of an imploded fast ignition configuration are shown accounting for the increased beam divergence found in re

  39. M. I. Ostrovskii, V. S. Shulman, L. Turowska

    We show that the open unit ball of the space of operators from a finite dimensional Hilbert space into a separable Hilbert space (we call it &#34;operator ball&#34;) has a restricted form of normal structure if we endow it with a hyperbolic metric (which is an analogue of the standard hyperbolic metric on the unit disc in the complex plane). We use this resu

  40. Christopher A. Merchant, Nina Markovic

    Low-temperature measurements of asymmetric carbon nanotube (CNT) quantum dots are reported. The CNTs are end-contacted with one ferromagnetic and one normal-metal electrode. The measurements show a spin-dependent rectification of the current caused by the asymmetry of the device. This rectification occurs for gate voltages for which the normal-metal lead is

  41. Eef van Beveren, George Rupp

    We argue that the resonance-like structures Y(4260) (arXiv:hep-ex/0506081,arXiv:0707.2541), Y(4360), Y(4660) (arXiv:0707.3699) and Y(4635) (arXiv:0807.4458), which were recently reported to have been observed in experiment, are non-resonant manifestations of the Regge zeros that appear in the production amplitude of the Resonance-Spectrum Expansion. Charmoni

  42. M. Spavone, E. Iodice, R. Calvi, D. Bettoni

    In this paper we present a detailed study of the peculiar early-type galaxy NGC1947. The main goal of this work is to constrain the dynamical status and the formation history of NGC1947 by comparing the observed properties with the predictions derived from different galaxy formation scenarios. To this aim, we derived the photometric and kinematical propertie

  43. Thayne Currie, Nancy Remage Evans, Brad Spitzbart, Jonathan Irwin

    We describe Chandra/ACIS-I observations of the massive ~ 13--14 Myr-old cluster, h Persei, part of the famous Double Cluster (h and chi Persei) in Perseus. Combining the list of Chandra-detected sources with new optical/IR photometry and optical spectroscopy reveals ~ 165 X-ray bright stars with V < 23. Roughly 142 have optical magnitudes and colors consiste

  44. W. Plessas, T. Melde

    Latest results from a study of baryon ground and resonant states within relativistic constituent quark models are reported. After recalling some typical spectral properties, the description of ground states, especially with regard to the nucleon and hyperon electromagnetic structures, is addressed. In the following, recent covariant predictions for pion, eta

  45. M. D. Scherbin

    In this paper we conjecture that some specific properties of an electroactive region of thunderclouds play the major role in an initiation of a lightning flash. The electroactive region is modeled here as a quantum two-level system of oxygen molecules which are assumed to have two (ground and excited) states, where transitions from ground to excited states c

  46. Z. Bagoly, L. Borgonovo, A. Meszaros, L. G. Balazs

    We study statistically 197 long gamma-ray bursts, detected and measured in detail by the BATSE instrument of the Compton Gamma-Ray Observatory. In the sample 10 variables, describing for any burst the time behavior of the spectra and other quantities, are collected. The factor analysis method is used to find the latent random variables describing the tempora

  47. Yurii Averboukh

    In this paper the set of value functions of all-possible zero-sum differential games with terminal payoff is characterized. The necessary and sufficient condition for a given function to be a value of some differential game with terminal payoff is obtained.

  48. D. Salabert, A. Eff-Darwich, R. Howe, S. G. Korzennik

    We used the m-averaged spectrum technique (&#34;collapsogram&#34;) to extract the low-frequency solar p-mode parameters of low- and intermediate-angular degrees (l \leq 35) in long time series of GONG and MDI observations. Rotational splittings and central frequencies have been measured down to ~850\muHz, including predicted modes which have not been measure

  49. R. Winkler, Dimitrie Culcer, S. J. Papadakis, B. Habib

    This paper reviews the spin orientation of spin-3/2 holes in quantum wells. We discuss the Zeeman and Rashba spin splitting in hole systems that are qualitatively different from their counterparts in electron systems. We show how a systematic understanding of the unusual spin-dependent phenomena in hole systems can be gained using a multipole expansion of th

  50. Hans Vernaeve

    We study Banach $\widetilde{\mathbb C}$-algebras, i.e., complete ultra-pseudo-normed algebras over the ring $\widetilde{\mathbb C}$ of Colombeau generalized complex numbers. We develop a spectral theory in such algebras. We show by explicit examples that important parts of classical Banach algebra theory do not hold for general Banach $\widetilde{\mathbb C}$

  51. M. Jura, J. Farihi, B. Zuckerman

    Spitzer Space Telescope spectra reveal 10 micron silicate emission from circumstellar dust orbiting six externally-polluted white dwarfs. Micron-size glasses with an olivine stoichiometry can account for the distinctively broad wings that extend to 12 microns; these particles likely are produced by tidal-disruption of asteroids. The absence of infrared PAH f

  52. P. Zasche

    Twenty eclipsing binaries were selected for an analysis from a huge database of observations made by the INTEGRAL/OMC camera. The photometric data were processed and analyzed, resulting in a first light-curve study of these neglected eclipsing binaries. Most of the selected systems are the detached ones. The system ET Vel was discovered to be an eccentric on

  53. Vitor O. Ferreira, Lucia S. I. Murakami

    As an instance of a linear action of a Hopf algebra on a free associative algebra, we consider finite group gradings of a free algebra induced by gradings on the space spanned by the free generators. The homogeneous component corresponding to the identity of the group is a free subalgebra which is graded by the usual degree. We look into its Hilbert series a

  54. Claudio M. Horowitz, Federico Roma, Ezequiel V. Albano

    The growth of ballistic aggregates on deterministic fractal substrates is studied by means of numerical simulations. First, we attempt the description of the evolving interface of the aggregates by applying the well-established Family-Vicsek dynamic scaling approach. Systematic deviations from that standard scaling law are observed, suggesting that significa

  55. Joerg Kampen

    We compute the length of geodesics on a Riemannian manifold by regular polynomial interpolation of the global solution of the eikonal equation related to the line element $ds^2=g_{ij}dx^idx^j$ of the manifold. Our algorithm approximates the length functional in arbitrarily strong Sobolev norms. Error estimates are obtained where the geometric information is

  56. Suzy Collin

    The main properties of AGN are reviewed, focussing on the accretion process and on the question of whether AGN are the best factories of ultra high energy particles and photons. I recall the large differences between the accretion/ejection flows in strong and weak accretors, and I conclude that, since low luminosity AGN and even &#34;dormant&#34; massive bla

  57. J. C. Phillips

    The realization of high-transition-temperature superconductivity (HTSC) confined to nanometre-sized interfaces has been a long-standing goal because of potential applications and the opportunity to study quantum phenomena in reduced dimensions. Here we discuss HTSC at free surfaces, interfaces, and nanoscale cluster surfaces, and show that the percolative se

  58. Giovanni Peccati, Murad S. Taqqu

    This survey provides a unified discussion of multiple integrals, moments, cumulants and diagram formulae associated with functionals of completely random measures. Our approach is combinatorial, as it is based on the algebraic formalism of partition lattices and Möbius functions. Gaussian and Poisson measures are treated in great detail. We also present seve

  59. V. A. Shcherbacov

    It is proved that any left F-quasigroup is isomorphic to the direct product of a left F-quasigroup with a unique idempotent element and isotope of a special form of a left distributive quasigroup. The similar theorems are proved for right F-quasigroups, left and right SM- and E-quasigroups. Information on simple quasigroups from these quasigroup classes is g

  60. M. R. Ramezanali, M. M. Vazifeh, Reza Asgari, Marco Polini

    At low energies, electrons in doped graphene sheets are described by a massless Dirac fermion Hamiltonian. In this work we present a semi-analytical expression for the dynamical density-density linear-response function of noninteracting massless Dirac fermions (the so-called &#34;Lindhard&#34; function) at finite temperature. This result is crucial to descri

  61. Lokesh Bharti, Chandan Joshi, S. N. A. Jaaffrey, Rajmal Jain

    We present spectropolarimetric analysis of umbral dots and a light bridge fragment that show dark lanes in G-band images. Umbral dots show upflow as well as associated positive Stokes V area asymmetry in their central parts. Larger umbral dots show down flow patches in their surrounding parts that are associated with negative Stokes V area asymmetry. Umbral

  62. Dganit Meidan, Yuval Oreg

    We study theoretically orbital effects of a parallel magnetic field applied to a disordered superconducting film. We find that the field reduces the phase stiffness and leads to strong quantum phase fluctuations driving the system into an insulating behavior. This microscopic model shows that the critical field decreases with the sheet resistance, in agreeme

  63. Anthony J. Creaco, Nikos Kalogeropoulos

    We point out that a special case of an ideal gas exhibits concentration of the volume of its phase space, which is a sphere, around its equator in the thermodynamic limit. The rate of approach to the thermodynamic limit is determined. Our argument relies on the spherical isoperimetric inequality of Lévy and Gromov.

  64. Mieke Gorissen, Jef Hooyberghs, Carlo Vanderzande

    Cumulants of a fluctuating current can be obtained from a free energy-like generating function which for Markov processes equals the largest eigenvalue of a generalized generator. We determine this eigenvalue with the DMRG for stochastic systems. We calculate the variance of the current in the different phases, and at the phase transitions, of the totally as

  65. Bjorn Gustafsson, Mihai Putinar, Ed Saff, Nikos Stylianopoulos

    Growth estimates of complex orthogonal polynomials with respect to the area measure supported by a disjoint union of planar Jordan domains (called, in short, an archipelago) are obtained by a combination of methods of potential theory and rational approximation theory. The study of the asymptotic behavior of the roots of these polynomials reveals a surprisin

  66. Martin Albrecht, Gregory Bard, William Hart

    We describe an efficient implementation of a hierarchy of algorithms for multiplication of dense matrices over the field with two elements (GF(2)). In particular we present our implementation -- in the M4RI library -- of Strassen-Winograd matrix multiplication and the &#34;Method of the Four Russians&#34; multiplication (M4RM) and compare it against other av

  67. Ö. Açık, Ü. Ertem, M. Önder, A. Verçin

    It has been shown that for each Killing-Yano (KY)-form accepted by an $n$-dimensional (pseudo)Riemannian manifold of arbitrary signature, two basic gravitational currents can be defined. Conservation of the currents are explicitly proved by showing co-exactness of the one and co-closedness of the other. Some general geometrical facts implied by these conserv

  68. Sarah Wright, Tshilidzi Marwala

    This paper investigates the use of different Artificial Intelligence methods to predict the values of several continuous variables from a Steam Generator. The objective was to determine how the different artificial intelligence methods performed in making predictions on the given dataset. The artificial intelligence methods evaluated were Neural Networks, Su

  69. Bulent Gonul, Ebru Bakir, Koray Koksal

    Low-lying energy levels of two interacting electrons confined in a two-dimensional parabolic quantum dot in the presence of an external magnetic field have been revised within the frame of a novel model. The present formalism, which gives closed algebraic solutions for the specific values of magnetic field and spatial confinement length, enables us to see ex

  70. Yacine Mehtar-Tani

    An iterative proceedure is proposed to compute the classical gauge field produced in the collision of two heavy nuclei at high energy. The leading order is obtained by linearizing the Yang-Mills equations in the light-cone gauge, and provides a simple formula for gluon production in nucleus-nucleus collisions. At this order $k_t-$factorization breaks down.

  71. Mary C. Meyer

    Regression splines are smooth, flexible, and parsimonious nonparametric function estimators. They are known to be sensitive to knot number and placement, but if assumptions such as monotonicity or convexity may be imposed on the regression function, the shape-restricted regression splines are robust to knot choices. Monotone regression splines were introduce

  72. Simon Harris, Matthew Roberts

    We give new results on the growth of the number of particles in a dyadic branching Brownian motion which follow within a fixed distance of a path $f:[0,\infty)\to \mathbb{R}$. We show that it is possible to count the number of particles without rescaling the paths. Our results reveal that the number of particles along certain paths can oscillate dramatically

  73. Robert Dunn, Rob Fender, Elmar Koerding, Clement Cabanac

    We present preliminary results on a global study of X-ray binaries using 14 Ms of data from the Rossi X-ray Timing Explorer satellite. Our initial study on GX 339-4 is recapped as an introduction to the methods used. We use a consistent analysis scheme for all objects, with three different spectral models to fit the powerlaw and disc components. We also take

  74. M. I. Ostrovskii

    Let $B_Y$ denote the unit ball of a normed linear space $Y$. A symmetric, bounded, closed, convex set $A$ in a finite dimensional normed linear space $X$ is called a {\it sufficient enlargement} for $X$ if, for an arbitrary isometric embedding of $X$ into a Banach space $Y$, there exists a linear projection $P:Y\to X$ such that $P(B_Y)\subset A$. The main re

  75. Daniela M. Witten, Robert Tibshirani

    We consider the problem of testing the significance of features in high-dimensional settings. In particular, we test for differentially-expressed genes in a microarray experiment. We wish to identify genes that are associated with some type of outcome, such as survival time or cancer type. We propose a new procedure, called Lassoed Principal Components (LPC)

  76. Philip B. Stark

    Post-election audits use the discrepancy between machine counts and a hand tally of votes in a random sample of precincts to infer whether error affected the electoral outcome. The maximum relative overstatement of pairwise margins (MRO) quantifies that discrepancy. The electoral outcome a full hand tally shows must agree with the apparent outcome if the MRO

  77. Yuliya Lashko, Gennady Filippov

    Within the microscopic model based on the algebraic version of the resonating group method the role of the Pauli principle in the formation of continuum wave function of nuclear systems composed of three identical $s$-clusters has been investigated. Emphasis is placed upon the study of the exchange effects contained in the genuine three-cluster norm kernel.

  78. J. Freudenberger, K. -H. Mueller, G. Fuchs, M. Wolf

    In this study pseudoquaternary rare-earth nickel borocarbide superconductors RxR&#39;1-xNi2B2C have been investigated predominantly in the diluted limit x << 1 or (1 x) << 1. In all of these materials structural disorder results in a reduction of the superconducting transition temperature Tc . Depending on the selection of the rare earth elements R and R&#39

  79. Salah A. Aly, Ahmed E. Kamal

    In this paper we develop network protection schemes against two link failures in optical networks. The motivation behind this work is the fact that the majority of all available links in an optical network suffer from single and double link failures. In the proposed network protection schemes, NPS2-I and NPS2-II, we deploy network coding and reduced capacity

  80. Kaushik Bhattacharya, Sarira Sahu

    In this work we calculate the decay rate of the electron type neutrinos into $W$ bosons and electrons in presence of an external uniform magnetic field. The decay rate is calculated from the imaginary part of the $W$ exchange neutrino self-energy diagram but in the weak field limit and compare our result with the existing one.

  81. D. Barbato, F. Flandoli, F. Morandin

    A shell-type model of an inviscid fluid, previously considered in the literature, is investigated in absence of external force. Energy dissipation of positive solutions is proved and decay of energy like $t^{-2}$ is established. Self-similar decaying positive solutions are introduced and proved to exist and classified. Coalescence and blow-up are obtained as

  82. Parijat Thakur, H. B. Ann, Ing-Guey Jiang

    We have performed smoothed particle hydrodynamics (SPH) simulations to study the response of the central kiloparsec region of a gaseous disk to the imposition of nonaxisymmetric bar potentials. The model galaxies are composed of the three axisymmetric components (halo, disk, and bulge) and a non-axisymmetric bar. These components are assumed to be invariant

  83. L. Fraser Jackson, Alistair G. Gray, Stephen E. Fienberg

    Large contingency tables arise in many contexts but especially in the collection of survey and census data by government statistical agencies. Because the vast majority of the variables in this context have a large number of categories, agencies and users need a systematic way of constructing tables which are summaries of such contingency tables. We propose

  84. A. V. Nikolaev, A. V. Bibikov, A. V. Avdeenkov, I. V. Bodrenko

    We study one dimensional (1D) carbon ribbons with the armchair edges and the zigzag carbon nanotubes and their counterparts with finite length (0D) in the framework of the Hückel model. We prove that a 1D carbon ribbon is metallic if its width (the number of carbon rings) is equal to $2+3n$. We show that the dispersion law (electron band energy) of a 1D meta

  85. Nina B. Bogdanova, B. M. Terziyska

    Approximation of the previously estimated excess specific heat C^{excess}/T^{5} of two fluoropolymers, PTFE and PCTFE, is presented using Orthonormal Polynomial Expansion Method (OPEM). The new type of weighting functions in OPEM involves the experimental errors in every point of the studied thermal characteristic. The investigated temperature dependence of

  86. Pierre Kervella, Frédéric Thévenin, Monika Petr-Gotzens

    - Context: The triple stellar system delta Vel system presents a significant infrared excess, whose origin is still being debated. A large infrared bow shock has been discovered using Spitzer/MIPS observations. Although it appears as a significant contributor to the measured IR excess, the possibility exists that a circumstellar IR excess is present around t

  87. CLAS Collaboration, M. Battaglieri, R. De Vita, A. P. Szczepaniak

    We report on the results of the first measurement of exclusive $f_0(980)$ meson photoproduction on protons for $E_γ=3.0 - 3.8$ GeV and $-t = 0.4-1.0$ GeV$^2$. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The resonance was detected via its decay in the $π^+ π^-$ channel by performing a partial wave analysis

  88. H. Anderhub, S. Vercellone, I. Donnarumma, F. D&#39;Ammando

    We report upper limits to the very high energy flux (E>100 GeV) of the flat spectrum radio quasar 3C454.3 (z=0.859) derived by the Cherenkov telescope MAGIC during the high states of July/August and November/December 2007. We compare the upper limits derived in both time slots with the available quasi-simultaneous MeV-GeV data from the AGILE gamma-ray satell

  89. Jerome H. Friedman, Bogdan E. Popescu

    General regression and classification models are constructed as linear combinations of simple rules derived from the data. Each rule consists of a conjunction of a small number of simple statements concerning the values of individual input variables. These rule ensembles are shown to produce predictive accuracy comparable to the best methods. However, their

  90. Warren Dicks, Makoto Sakuma

    To each once-punctured-torus bundle, $T_ϕ$, over the circle with pseudo-Anosov monodromy $ϕ$, there are associated two tessellations of the complex plane: one, $Δ(ϕ)$, is (the projection from $\infty$ of) the triangulation of a horosphere at $\infty$ induced by the canonical decomposition into ideal tetrahedra, and the other, $CW(ϕ)$, is a fractal tessellati

  91. S. Basak, S. Prunet, K. Benabed

    We present a fast, arbitrarily accurate method to simulate the effect of gravitational lensing of the Cosmic Microwave Background anisotropies and polarization fields by large scale structures. We demonstrate the efficiency and accuracy of the method and exhibit their dependence on the algorithm parameters.

  92. Hiroaki Nishioka, Fu-Cheng Wang, Jiun-Huei Proty Wu, Paul T. P. Ho

    We describe methods used to validate data from the Y.T. Lee Array for Microwave Background Anisotropy (AMiBA), an interferometric array designed to measure the Sunyaev-Zel&#39;dovich effect and the anisotropy of the Cosmic Microwave Background (CMB). We perform several statistical tests on data from pointed galaxy cluster observations taken in 2007 and noise

  93. S. V. Gaponenko, D. V. Guzatov

    We extend the Purcell&#39;s original idea [Phys. Rev. \textbf{69}, 682 (1946)] on modification of photon spontaneous \textit{emission} rate to modification of photon spontaneous \textit{scattering} rate. We find the interplay of local incident field enhancement and local density of photon states enhancement in close proximity to a silver nanoparticle may res

  94. M. Zawada, R. Abdoul, J. Chwedeńczuk, R. Gartman

    We report on our study of the free-fall expansion of a finite-temperature Bose-Einstein condensed cloud of 87Rb. The experiments are performed with a variable total number of atoms while keeping constant the number of atoms in the condensate. The results provide evidence that the BEC dynamics depends on the interaction with thermal fraction. In particular, t

  95. J. -F. Desmurs, C. Codella, J. Santiago-Garcia, M. Tafalla

    We imaged the protostars of the nearby region NGC1333 IRAS 4 in the water maser line at 22.2 GHz by using the VLBA in phase referencing at milliarcsecond scale over four epochs spaced by one month to measure proper motions. We measure the absolute positions and proper motions of the H2O spots to investigate the kinematics of the region from where the jet is

  96. H. M. Guenther, S. P. Matt, Z. -Y. Li

    Some T Tauri stars show a peculiar X-ray spectrum that can be modelled by two components with different absorbing column densities. We seek to explain the soft X-ray component in DG Tau, the best studied of these sources, with an outflow model, taking observations at other wavelengths into consideration. We constrain the outflow properties through spectral f

  97. Marco Faella

    We consider games played on finite graphs, whose goal is to obtain a trace belonging to a given set of winning traces. We focus on those states from which Player 1 cannot force a win. We explore and compare several criteria for establishing what is the preferable behavior of Player 1 from those states. Along the way, we prove several results of theoretical a

  98. Louis Lyons

    Many statistical issues arise in the analysis of Particle Physics experiments. We give a brief introduction to Particle Physics, before describing the techniques used by Particle Physicists for dealing with statistical problems, and also some of the open statistical questions.

  99. Silas Laycock, Jeremy J. Drake

    We report the discovery of a flaring X-ray source with an optical counterpart with Halpha emission and red-excess, in the direction of the SMC. A 100 ksec X-ray observation with Chandra detected a flare lasting 6 ksec in the source CXO J005428.9-723107. The X-ray spectrum during the flare was consistent with a thermal plasma of temperature kT=2.5 keV. In qui

  100. Ken-Ichi Ishikawa

    I review recent machine trends and algorithmic developments for dynamical lattice QCD simulations with the HMC algorithm for Wilson-type fermions. The topics include the trend toward multi-core processors and general purpose GPU (GPGPU) computing, and improvements on the quark determinant preconditioning, molecular dynamics integrator, and quark solvers. I a