March 2006 arXiv papers — page 23

Gil I. Shamir

Universal compression of patterns of sequences generated by independently identically distributed (i.i.d.) sources with unknown, possibly large, alphabets is investigated. A pattern is a sequence of indices that contains all consecutive indices in increasing order of first occurrence. If the alphabet of a source that generated a sequence is unknown, the inev

Evgeniy Grigoriev

The OverRelational Manifesto (below ORM) proposes a possible approach to creation of data storage systems of the next generation. ORM starts from the requirement that information in a relational database is represented by a set of relation values. Accordingly, it is assumed that the information about any entity of an enterprise must also be represented as a

Peter E. Falloon, Rodolfo A. Jalabert, Dietmar Weinmann, Robert L. Stamps

We study electron transport through a domain wall in a ferromagnetic nanowire subject to spin-dependent scattering. A scattering matrix formalism is developed to address both coherent and incoherent transport properties. The coherent case corresponds to elastic scattering by static defects, which is dominant at low temperatures, while the incoherent case pro

Kensuke Inaba Akihisa Koga

We investigate the two-orbital Hubbard model in infinite dimensions by means of the self-energy functional method. By calculating the entropy, susceptibility, and quasi-particle weight at zero temperature, we determine the phase diagram for the system with same and different bandwidths, which is compared with that obtained recently. It is clarified that orbi

H. K. Choi, W. O. Lee, Y. S. OH, K. H. Kim

We report on the anomalous Hall coefficient and longitudinal resistivity scaling relationships on a series of annealed Ga1-xMnxAs epilayers (x~0.055). As-grown samples exhibit scaling parameter n of ~ 1. Near the optimal annealing temperature, we find n ~ 2 to be consistent with recent theories on the intrinsic origins of anomalous Hall Effect in Ga1-xMnxAs.

Allan D. Boardman, Neil King, Yuriy Rapoport, Larry Velasco

Surface wave propagation at the interface between different types of gyrotropic materials and an isotropic negatively refracting medium, in which the relative permittivity and relative permeability are, simultaneously, negative is investigated. A general approach is taken that embraces both gyroelectric and gyromagnetic materials, permitting the possibility

Alexander Borisenko, Alexander Bakai

A generalized tunneling model of multicomponent insulating glasses is formulated, considering tunneling states to be paramagnetic centers of the electronic hole type. The expression for magnetic field dependent contribution into the free energy is obtained. The derivation is made of the expression for the nonmonotonic magnetic field dependence of dielectric

T. A. Pasquini, M. Saba, G. Jo, Y. Shin

We studied quantum reflection of Bose-Einstein condensates at normal incidence on a square array of silicon pillars. For incident velocities of 2.5-26 mm/s observations agreed with theoretical predictions that the Casimir-Polder potential of a reduced density surface would reflect slow atoms with much higher probability. At low velocities (0.5-2.5 mm/s), we

I. Nagy, M. J. Puska, N. Zabala

We study numerically the existence and character of bound states for positive and negative point charges shielded by the response of a two-dimensional homogeneous electron gas. The problem is related to many physical situations and has recently arisen in experiments for impurities on metal surfaces with Schockley surface states. Mathematical theorems ascerta

Peter P. Vasil'ev, Igor V. Smetenin

It has been theoretically shown that in large-density semiconductor plasma there exist an energy level of a bound electron-hole pair (a composite boson) at the band gap. Filling this level up occurs through the condensation of electron-hole pairs with the use of mediating photons of a resonant electromagnetic field. We have demonstrated that in the case of a

M. K. Ramazanoglu, P. S. Clegg, S. Wakimoto, R. J. Birgeneau

Ba$_2$Cu$_3$O$_4$Cl$_2$ has two inter-penetrating square Cu sublattices, one with square root 2 times the in-plane spacing of the other. Isotropic magnetic interactions between the two sublattices are completely frustrated. Quantum fluctuations resolve the intrinsic degeneracy in the ordering direction of the more weakly coupled sublattice in favor of collin

J Krawczyk, T Prellberg, AL Owczarek, A Rechnitzer

We introduce a new class of models for polymer collapse, given by random walks on regular lattices which are weighted according to multiple site visits. A Boltzmann weight $ω_l$ is assigned to each $(l+1)$-fold visited lattice site, and self-avoidance is incorporated by restricting to a maximal number $K$ of visits to any site via setting $ω_l=0$ for $l\geq

A. F. Dethlefsen, R. J. Haug, K. Vyborny, O. Certik

The dependence of the activated gap on magnetic field is studied for the fractional filling factor~1/3. By comparing the experimental results with results from exact diagonalization calculations we are able to identify the excitation of a small antiskyrmion in the low-field regime and a cross-over to spinless excitations at higher magnetic fields. The effect

Krzysztof Sacha, Eddy Timmermans

We consider the self-localization of neutral impurity atoms in a Bose-Einstein condensate in a 1D model. Within the strong coupling approach, we show that the self-localized state exhibits parametric soliton behavior. The corresponding stationary states are analogous to the solitons of non-linear optics and to the solitonic solutions of the Schroedinger-Newt

R. Fetzer, M. Rauscher, A. Münch, B. A. Wagner

In this study, we present a novel method to assess the slip length and the viscosity of thin films of highly viscous Newtonian liquids. We quantitatively analyse dewetting fronts of low molecular weight polystyrene melts on Octadecyl- (OTS) and Dodecyltrichlorosilane (DTS) polymer brushes. Using a thin film (lubrication) model derived in the limit of large s

Karel Vyborny

A system at filling factor 2/3 could be a candidate for a quantum Hall ferromagnet at integer filling factor of composite fermions. Using exact diagonalization with electrons on a torus we study the transition from the singlet ground state to the polarized ground state at this filling and look for signatures of quantum Hall ferromagnetism. Differences betwee

Akinori Awazu

The transport phenomena of a nonequilibrium lattice gas system are investigated. We consider a simple system that consists of two particles interacting repulsively and the potential forces acting on these particles. Under an external driving field applied to only one particle, we found the following relation between the mean velocity of the driven particle a

Choong H. Kim, Hyun C. Lee

The infinite-$U$ Anderson model coupled to a Jahn-Teller phonon is studied using the slave boson method on the basis of the large degeneracy expansion (1/N) scheme. The model Hamiltonian acts on the orbital degrees of freedom. The main focus is on the interplay between strong local electron correlation and weak Jahn-Teller electron-phonon interaction. The Ko

K. Sasaki, S. Murakami, R. Saito

It has been known that edge states of a graphite ribbon are zero-energy, localized eigen-states. We show that next nearest-neighbor hopping process decreases the energy of the edge states at zigzag edge with respect to the Fermi energy. The energy reduction of the edge states is calculated analytically by first-order perturbation theory and numerically. The

C. Hess, P. Ribeiro, B. Büchner, H. ElHaes

The magnon thermal conductivity $κ_{\mathrm{mag}}$ of the spin ladders in $\rm Sr_{14}Cu_{24-x}Zn_xO_{41}$ has been investigated at low doping levels $x=0$, 0.125, 0.25, 0.5 and 0.75. The Zn-impurities generate nonmagnetic defects which define an upper limit for $l_{\mathrm{mag}}$ and therefore allow a clear-cut relation between $l_{\mathrm{mag}}$ and $κ_{\m

Ted von Hippel, William H. Jefferys, James Scott, Nathan Stein

We demonstrate a new Bayesian technique to invert color-magnitude diagrams of main sequence and white dwarf stars to reveal the underlying cluster properties of age, distance, metallicity, and line-of-sight absorption, as well as individual stellar masses. The advantages our technique has over traditional analyses of color-magnitude diagrams are objectivity,

Rajib Ganguly, Kenneth R. Sembach, Todd M. Tripp, Blair D. Savage

We present FUSE and HST/STIS observations of the absorption line system near the emission redshift of the radio-quiet, X-ray bright quasar HE0226-4110 (z = 0.495, V=15.2). The spectra cover the rest-frame wavelength range 610--1150 A, and we detect a wide range of ionization species, including four adjacent stages of oxygen (O III-VI), which reveal a strikin

Dennis Zaritsky, Anthony H. Gonzalez, Ann I. Zabludoff

The fundamental manifold (FM), an extension of the fundamental plane formalism, incorporates all spheroid-dominated stellar systems from dwarf ellipticals up to the intracluster stellar populations of galaxy clusters by accounting for the continuous variation of the mass-to-light ratio within the effective radius r_e with scale. Here, we find that Local Grou

T. V. Smirnova, C. R. Gwinn, V. I. Shishov

We studied the turbulence spectrum of the local interstellar plasma in the direction of PSR J0437-4715, on the basis of our observations and those reported earlier by others. We combine these data to form a structure function for the variations of phase along the line of sight to the pulsar. For observations that did not report them, we infer modulation indi

Ruslan Belikov, N. Jeremy Kasdin, Robert J. Vanderbei

Pupil mapping is a promising and unconventional new method for high contrast imaging being considered for terrestrial exoplanet searches. It employs two (or more) specially designed aspheric mirrors to create a high-contrast amplitude profile across the telescope pupil that does not appreciably attenuate amplitude. As such, it reaps significant benefits in l

Dario Fadda, F. R. Marleau, L. J. Storrie-Lombardi, D. Makovoz

We present the reduction of the 24 micron data obtained during the first cosmological survey performed by the Spitzer Space Telescope (First Look Survey, FLS). The survey consists of a shallow observation of 2.5x2 sq deg centered at 17h18m +59d30m (main survey) and a deeper observation of 1x0.5 sq deg centered at 17h17m +59d45m(verification survey). Issues w

Ingo Berentzen, Isaac Shlosman

We study the growth of galactic disks in live triaxial DM halos. The halos have been assembled through constrained realizations method and evolved from the linear regime using cosmological simulations. The `seed' disks have been inserted at redshift z=3 and increased in mass tenfold over various time periods, ~1-3 Gyr, with the halo responding quasi-adia

Beth Willman, Morad Masjedi, David W. Hogg, Julianne J. Dalcanton

SDSSJ1049+5103, commonly known as Willman 1, is an extremely low-luminosity Milky Way companion whose properties are intermediate between those of globular clusters and dwarf spheroidals. In this paper, we use deep photometry to show that this object is old and moderately metal-poor, has a distance of 38 +/- 7 kpc, has an M_V of -2.5 mag, and has a half-ligh

Franck Delahaye, Anil K. Pradhan, Claude J. Zeippen

Helium-like ions provide the most important X-ray spectral diagnostics in high temperature fusion and astrophysical plasmas. We previously presented computed collision strengths for O~VII including relativistic fine structure, levels up to the $n=4$ complex and radiation damping of autoionizing resonances. We have extended this work to other He-like ions (N,

N. Bucciantini, L. Del Zanna

We present here a series of numerical simulations of the development of Kelvin-Helmholtz instability in a relativistically hot plasma. The physical parameters in the unperturbed state are chosen to be representative of local conditions encountered in Pulsar Wind Nebulae (PWNe), with a main magnetic field perpendicular to a mildly relativistic shear layers. B

B. Nikolic, P. Alexander, D. Ford

We have combined up-to-date stellar population synthesis models, a simple radiative transfer approach, and a fully comprehensive dust model with the aim of developing a simple but quantitative way of interpreting the mid-infrared spectra of galaxies. We apply these models to the observed correlations of mid-infrared luminosities (at 8 and 24 micron) with the

S. Campana, G. Tagliaferri, D. Lazzati, G. Chincarini

Short duration (<2 s) Gamma-ray bursts (GRBs) have been a mystery since their discovery. Until May 2005 very little was known about short GRBs, but this situation has changed rapidly in the last few months since the Swift and HETE-2 satellites have made it possible to discover X-ray and optical counterparts to these sources. Positional associations indicate

D. Ward-Thompson, P. Andre, R. Crutcher, D. Johnstone

We review the properties of low mass dense molecular cloud cores, including starless, prestellar, and Class 0 protostellar cores, as derived from observations. In particular we discuss them in the context of the current debate surrounding the formation and evolution of cores. There exist several families of model scenarios to explain this evolution (with man

Federica Govoni

The existence of magnetic fields associated with the intracluster medium in clusters of galaxies is now well established through different methods of analysis. The most detailed evidence for the presence of cluster magnetic fields comes from radio observations. Magnetic fields can be investigated through the synchrotron emission of cluster-wide diffuse sourc

A. D. Mackey, M. J. Payne, G. F. Gilmore

We present the results of photometric measurements from images of the LMC cluster ESO 121-SC03 taken with HST/ACS. Our resulting CMD reaches 3 magnitudes below the main-sequence turn-off, representing the deepest observation of this cluster to date. We also present similar photometry from ACS imaging of the accreted Sagittarius dSph cluster Pal. 12, used in

Emilio Donoso, Ana L. O&#39;Mill, Diego G. Lambas

We analyse a high redshift sample ($0.4<z<0.5$) of LRG&#39;s extracted from the Sloan Digital Sky Survey Data Release 4 and their surrounding structures to explore the presence of alignment effects of these bright galaxies with neighbor objects. In order to avoid projection effects we compute photometric redshifts for galaxies within $3~\mpc$ in projection o

T. Tsuribe, K. Omukai

Dynamical collapse and fragmentation of low-metallicity cloud cores is studied using three-dimensional hydrodynamical calculations, with particular attention devoted whether the cores fragment in the dust-cooling phase or not. The cores become elongated in this phase, being unstable to non-spherical perturbation due to the sudden temperature decrease. In the

L. Kuiper, W. Hermsen, P. R. den Hartog, W. Collmar

We report on the discovery of hard spectral tails for energies above 10 keV in the total and pulsed spectra of anomalous X-ray pulsars 1RXS J1708-4009, 4U 0142+61 and 1E 2259+586 using RXTE PCA (2-60 keV) and HEXTE (15-250 keV) data and INTEGRAL IBIS ISGRI (20-300 keV) data. Improved spectral information on 1E 1841-045 is presented. The pulsed and total spec

Wolfgang Reich

Following the detection of polarized diffuse Galactic emission in 1962 a number of surveys were undertaken at low frequencies in the following years resulting in important insights on the local magnetic field, polarization of the giant radio loops and other Galactic structures, as well as on the properties of the diffuse magnetized interstellar medium. This

J. Steinacker, A. Bacmann, Th. Henning

We present a ray-tracing technique for radiative transfer modeling of complex three-dimensional (3D) structures which include dense regions of high optical depth like in dense molecular clouds, circumstellar disks, envelopes of evolved stars, and dust tori around active galactic nuclei. The corresponding continuum radiative transfer problem is described and

Alexandre Marcowith, Martin Lemoine, Guy Pelletier

Supernovae remnant shock waves could be at the origin of cosmic rays up to energies in excess of the knee ($E\simeq3\cdot 10^{15} $eV) if the magnetic field is efficiently amplified by the streaming of accelerated particles in the shock precursor. This paper follows up on a previous paper \citep{pell05} which derived the properties of the MHD turbulence so g

Guy Pelletier, Martin Lemoine, Alexandre Marcowith

This paper investigates the nature of the MHD turbulence excited by the streaming of accelerated cosmic rays in a shock wave precursor. The two recognised regimes (non-resonant and resonant) of the streaming instability are taken into account. We show that the non-resonant instability is very efficient and saturates through a balance between its growth and n

Hiroyuki Hirashita, Hiroshi Shibai, Tsutomu T. Takeuchi

We investigate the possibility to search for metal-poor high column density (> 10^{23} cm^{-2}) clouds at high redshift (z) by using gamma ray burst (GRB) afterglows. Such clouds could be related to primeval galaxies which may cause a burst of star formation. We show that a large part of hydrogen is in molecular form in such a high column density environment

Sukyoung K. Yi, Suk-Jin Yoon

The UV upturn is the rising flux with decreasing wavelength between the Lyman limit and 2500Åfound virtually in all bright spheroidal galaxies. It has been a mystery ever since it was first detected by the OAO-2 space telescope (Code & Welch 1979) because such old metal-rich populations were not expected to contain any substantial number of hot stars. It was

N. A. Tikhonov, O. A. Galazutdinova, I. O. Drozdovsky

Aims. The extraplanar stellar populations of highly-inclined disk galaxies IC 2233, IC 5052, NGC 4631 and NGC 5023 are analyzed with the goal to quantify their vertical extent and structure. Methods. Based on the single-star photometry, we separate different stellar populations and analyze their spatial distribution. Results. On archival images obtained with

Masahiro N. Machida, Shu-ichiro Inutsuka, Tomoaki Matsumoto

The stellar core formation and high speed jets driven by the formed core are studied by using three-dimensional resistive MHD nested grid simulations. Starting with a Bonnor-Ebert isothermal cloud rotating in a uniform magnetic field, we calculate the cloud evolution from the molecular cloud core (n = 10^6 cm^-3, r_c = 4.6 times 10^4 AU) to the stellar core

David B. Fisher

I use Spitzer 3.6-8.0 μm color profiles to compare the radial structure of star formation in pseudobulges and classical bulges. Pseudobulges are ``bulges&#39;&#39; which form through secular evolution, rather than mergers. In this study, pseudobulges are identified using the presence of disk-like structure in the center of the galaxy (nuclear spiral, nuclear

S. Katsuda, H. Tsunemi

We present the detailed X-ray spectroscopy of Vela shrapnel A with the XMM-Newton satellite. Vela shrapnel A is one of several protrusions identified as bullets from Vela supernova explosion. The XMM-Newton image shows that shrapnel A consists of a bright knot and a faint trailing wake. We extracted spectra from various regions, finding a prominent Si Ly$_α$

Y. Shi, G. H. Rieke, C. Papovich, P. G. Perez-Gonzalez

We have studied the morphologies of luminous infrared galaxies (LIRGs; L_IR(8-1000um)>10^11 Lsun) at 0.3< z<1.4 in the HST Ultradeep Field (UDF) by calculating concentration and asymmetry indices and comparing the results with similar calculations for: (1) galaxies at similar redshift that are less infrared-active; and (2) local LIRGs. We find that the high-

M. W. Auger, C. D. Fassnacht, A. L. Abrahamse, L. M. Lubin

We report on the results of a spectroscopic survey of the environments of the gravitational lens systems CLASS B1600+434 (z_l = 0.41, z_s = 1.59) and CLASS B2319+051 (z_l = 0.62). The B1600+434 system has a time delay measured for it, and we find the system to lie in a group with a velocity dispersion of 100 km/s and at least six members. B2319+051 has a lar

Ian A. Bonnell, Richard B. Larson, Hans Zinnecker

We review recent advances in our understanding of the origin of the initial mass function (IMF). We emphasize the use of numerical simulations to investigate how each physical process involved in star formation affects the resulting IMF. We stress that it is insufficient to just reproduce the IMF, but that any successful model needs to account for the many o

Mark M. McKinnon

A statistical model of the polarization of pulsar radio emission is used to derive the general statistics of a polarization vector&#39;s orientation angles. The theoretical distributions are compared with orientation angle histograms computed from single-pulse, polarization observations of PSR B2020+28. The favorable agreement between the theoretical and mea

C. D. Fassnacht, J. P. McKean, L. V. E. Koopmans, T. Treu

We report the serendipitous discovery of two strong gravitational lens candidates (ACS J160919+6532 and ACS J160910+6532) in deep images obtained with the Advanced Camera for Surveys on the Hubble Space Telescope, each less than 40 arcsec from the previously known gravitational lens system CLASS B1608+656. The redshifts of both lens galaxies have been measur

I. A. Bonnell, C. J. Clarke, M. R. Bate

We use numerical simulations of the fragmentation of a 1000 solar mass molecular cloud and the formation of a stellar cluster to study how the initial conditions for star formation affect the resulting initial mass function (IMF). In particular, we are interested in the relation between the thermal Jeans mass in a cloud and the knee of the initial mass funct

W. Hofmann

The performance of Cherenkov instruments for the detection of very high energy gamma rays is ultimately limited by the fluctuations in the development of air showers. With particular emphasis on the angular resolution, the ultimate performance limits are investigated on the basis of simulations.

Michael Douglas, Zhiqin Lu

In this paper, we study the Chern classes on the moduli space of polarized Calabi-Yau manifolds. We prove that the integrations of the invariants of the curvature of the Weil-Petersson metric are finite. In some special cases, they are even rational numbers.

Ehud Hrushovski

Let $T$ be a first-order theory. A correspondence is established between internal covers of models of $T$ and definable groupoids within $T$. We also consider amalgamations of independent diagrams of algebraically closed substructures, and find strong relation between: covers, uniqueness for 3-amalgamation, existence of 4-amalgamation, imaginaries of $T^\si$

J. J. Blanco-Pillado, C. P. Burgess, J. M. Cline, C. Escoda

We present a new version of our racetrack inflation scenario which, unlike our original proposal, is based on an explicit compactification of type IIB string theory: the Calabi-Yau manifold P^4_[1,1,1,6,9]. The axion-dilaton and all complex structure moduli are stabilized by fluxes. The remaining 2 Kahler moduli are stabilized by a nonperturbative superpoten

Daniela Bertacchi, Fabio Zucca

We study weak and strong survival for branching random walks on multigraphs. We prove that, for a large class of multigraphs, weak survival is related to a geometrical parameter of the multigraph and that the existence of a pure weak phase is equivalent to nonamenability. Finally we study weak and strong critical behaviors of the branching random walk.

Shiri Artstein-Avidan, Yaron Ostrover

In this work we discuss a conjecture of Viterbo relating the symplectic capacity of a convex body and its volume. The conjecture states that among all 2n-dimensional convex bodies with a given volume the euclidean ball has maximal symplectic capacity. We present a proof of this fact up to a logarithmic factor in the dimension, and many classes of bodies for

Archil Kobakhidze

We describe a theory of gravitation on canonical noncommutative spacetimes. The construction is based on theta-twisted General Coordinate Transformations and Local Lorentz Invariance.

Shmuel Friedland, Leonid Gurvits

We derive here the Friedland-Tverberg inequality for positive hyperbolic polynomials. This inequality is applied to give lower bounds for the number of matchings in $r$-regular bipartite graphs. It is shown that some of these bounds are asymptotically sharp. We improve the known lower bound for the three dimensional monomer-dimer entropy. We present Ryser-li

Clovis Hopman, Dafne Guetta, Eli Waxman, Simon Portegies Zwart

Short-hard gamma-ray bursts (SHBs) may arise from gravitational wave (GW) driven mergers of double neutron star (DNS) systems. DNSs may be &#34;primordial&#34; or can form dynamically by binary exchange interactions in globular clusters during core-collapse. For primordial binaries, the time delay between formation and merger is expected to be short, tau~0.1

J. D. Cohn, Tzu-Ching Chang

The recently introduced models of reionization bubbles based on extended Press-Schechter theory (Furlanetto, Zaldarriaga & Hernquist 2004) are generalized to include mergers of ionization sources. Sources with a recent major merger are taken to have enhanced photon production due to star formation, and accretion onto a central black hole if a black hole is p

Elaine M. Sadler, Roberto Ricci, Ronald D. Ekers, J. A. Ekers

We present some first results on the variability, polarization and general properties of radio sources selected in a blind survey at 20 GHz, the highest frequency at which a sensitive radio survey has been carried out over a large area of sky. Sources with flux densities above 100 mJy in the AT20G Pilot Survey at declination -60 to -70 were observed at up to

Mushtaq Loan, Yi Ying

Standard Monte Carlo simulations have been performed for 3-dimensional U(1) lattice gauge model on improved lattices to measure the wavefunction and size of the scalar and the tensor glueballs. Our results show the radii of ~ 0.60 and ~ 1.12 in the units of string tension, or ~0.28 and ~0.52 fm, for the scalar and tensor glueballs, respectively. At finite te

Naoyuki Haba

In the 5D theory in which only 3 generation right-handed neutrinos are in the bulk, the neutrino flavor mixings and the mass spectrum can be constructed through the seesaw mechanism. The 5D seesaw is easily calculated just by a replacement of the Majorana mass eigenvalues, M_i, by 2 M_*tan(h)[πRM_i] (M_*: 5D Planck scale, R: compactification radius). The 5D

Horace W. Crater, Cheuk-Yin Wong, Peter Van Alstine

Two-Body Dirac equations of constraint dynamics provide a covariant framework to investigate the problem of highly relativistic quarks in meson bound states. This formalism eliminates automatically the problems of relative time and energy, leading to a covariant three dimensional formalism with the same number of degrees of freedom as appears in the correspo

E. Arashiro, H. A. Fernandes, J. R. Drugowich de Felicio

We investigate the short-time critical dynamics of the Baxter-Wu (BW) and $n=3$ Turban (3TU) models to estimate their global persistence exponent $θ_{g}$. We conclude that this new dynamical exponent can be useful in detecting differences between the critical behavior of these models which are very difficult to obtain in usual simulations. In addition, we es

A. S. Wilson, David A. Smith, A. J. Young

In this paper, we focus on the limb-brightened, prolate spheroidal cavity of the radio galaxy Cygnus A, as revealed by the Chandra X-ray Observatory. We use the shock heated, thermal intracluster medium around the expanding cavity to infer the properties of the radio synchrotron-emitting gas inside the cavity. The gas along the N and S edges of the cavity is

Rajesh Sundaresan

This paper considers the problem of guessing the realization of a finite alphabet source when some side information is provided. The only knowledge the guesser has about the source and the correlated side information is that the joint source is one among a family. A notion of redundancy is first defined and a new divergence quantity that measures this redund

B. Gendre, A. Galli, A. Corsi, A. Klotz

We analyze optical and X-ray observations of GRB 050904 obtained with TAROT and SWIFT. We perform temporal and spectral analysis of the X-ray and optical data. We find significant absorption in the early phase of the X-ray light curve, with some evidence (3 sigma level) of variability. We interpret this as a progressive photo-ionization. We investigate the e

Robert T. Jantzen, James W. York,

Based on the recent understanding of the role of the densitized lapse function in Einstein&#39;s equations and of the proper way to pose the thin sandwich problem, a slight readjustment of the minimal distortion shift gauge in the 3+1 approach to the dynamics of general relativity allows this shift vector to serve as the vector potential for the longitudinal

Daniel E. Severin

In this article, we study some new characterizations of primitive recursive functions based on restricted forms of primitive recursion, improving the pioneering work of R. M. Robinson and M. D. Gladstone in this area. We reduce certain recursion schemes (mixed/pure iteration without parameters) and we characterize one-argument primitive recursive functions a

Sergio De Carvalho Bezerra, Samy Tindel, Frederi Viens

This paper provides information about the asymptotic behavior of a one-dimensional Brownian polymer in random medium represented by a space-time Gaussian field W assumed to be white noise in time and function-valued in space. According to the behavior of the spatial covariance W, we give a lower bound on the power growth (wandering exponent) of the polymer w

M. Avellino, A. J. Fisher, S. Bose

We calculate the fidelity of transmission of a single qubit between distant sites on semi-infinite and finite chains of spins coupled via the magnetic dipole interaction. We show that such systems often perform better than their Heisenberg nearest-neighbour coupled counterparts, and that fidelities closely approaching unity can be attained between the ends o

Benoit Donnet, Bradley Huffaker, Timur Friedman, kc claffy

In the past few years, the network measurement community has been interested in the problem of internet topology discovery using a large number (hundreds or thousands) of measurement monitors. The standard way to obtain information about the internet topology is to use the traceroute tool from a small number of monitors. Recent papers have made the case that

Zhuo Li, Eli Waxman

Gamma-ray burst (GRB) afterglow emission is believed to be produced by synchrotron emission of electrons accelerated to high energy by a relativistic collisionless shock propagating into a weakly magnetized plasma. Afterglow observations have been used to constrain the post-shock magnetic field and structure, as well as the accelerated electron energy distri

Houri Ziaeepour

In cosmological context, classical scalar fields are important ingredients for inflation models, many candidate models of dark energy, symmetry breaking and phase transition epochs, and their consequences such as baryo and lepto-genesis. We investigate the formation of these fields by studying the production of a light quantum scalar field during the decay o

Le Zhang, Xuelei Chen, Yi-An Lei, Zongguo Si

The recombination history of the Universe provides a useful tool for constraining the annihilation of dark matter particles. Even a small fraction of dark matter particles annihilated during the cosmic dark age can provide sufficient energy to affect the ionization state of the baryonic gas. Although this effect is too small for neutralinos, lighter dark mat

Soumen Basak, Amir Hajian, Tarun Souradeep

We formulate statistical isotropy of CMB anisotropy maps in its most general form. We also present a fast and orientation independent statistical method to determine deviations from statistical isotropy in CMB polarization maps. Importance of having statistical tests of departures from SI for CMB polarization maps lies not only in interesting theoretical mot

Daan Krammer

We define pseudo-Garside groups and prove a theorem about them parallel to Garside&#39;s result on the word problem for the usual braid groups. The main novelty is that the set of simple elements can be infinite. We introduce a group B=B(Z^n) which we call the braid group of Z^n, and which bears some vague resemblance to mapping class groups. It is to GL(n,Z

Piotr Sniady

We study the shape of the Young diagram λassociated via the Robinson-Schensted-Knuth algorithm to a random permutation in S_n such that the length of the longest decreasing subsequence is not bigger than a fixed number d; in other words we study the restriction of the Plancherel measure to Young diagrams with at most d rows. We prove that in the limit n\to\i

Dirk Grupe, Peter Brown, Jay Cummings, Bing Zhang

We report the results of Swift observations of the Gamma Ray Burst GRB 050603. With a V magnitude V=18.2 about 10 hours after the burst the optical afterglow was the brightest so far detected by Swift and one of the brightest optical afterglows ever seen. The Burst Alert Telescope (BAT) light curves show three fast-rise-exponential-decay spikes with $T_{90}$

Julia E. Bergner

In this note we prove that Reedy fibrant Segal categories are fibrant objects in the model category structure SeCat_c. Combining this result with a previous one, we thus have that the fibrant objects are precisely the Reedy fibrant Segal categories. We also show that the analogous result holds for Segal categories which are fibrant in the projective model st

Michele Frigerio, Thomas Hambye, Ernest Ma

Instead of creating the observed baryon asymmetry of the universe by the decay of right-handed (RH) neutrinos to left-handed leptons, we propose to generate it dominantly by the decay of the RH neutrinos to RH leptons. This mechanism turns out to be successful in large regions of parameter space. It may work, in particular, at a scale as low as $\sim$~TeV, w

A. Edery, Luca Fabbri, M. B. Paranjape

We study the theory of Weyl conformal gravity with matter degrees of freedom in a conformally invariant interaction. Specifically, we consider a triplet of scalar fields and SO(3) non-abelian gauge fields, i.e. the Georgi-Glashow model conformally coupled to Weyl gravity. We show that the equations of motion admit solutions spontaneously breaking the conform

Andreas Bredthauer, Ulf Lindstrom, Jonas Persson, Maxim Zabzine

We give a physical derivation of generalized Kahler geometry. Starting from a supersymmetric nonlinear sigma model, we rederive and explain the results of Gualtieri regarding the equivalence between generalized Kahler geometry and the bi-hermitean geometry of Gates-Hull-Rocek. When cast in the language of supersymmetric sigma models, this relation maps preci

J. H. Field

Time-like and space-like invariant space-time intervals are used to analyse measurements of spatial and temporal distances defined by two spatially-separated clocks. The time dilatation effect is confirmed, but not `relativity of simultaneity' or `relativistic length contraction'. How these latter, spurious, effects arise from misuse of the Lorentz transform

Qing-Guo Huang, Miao Li, Wei Song

The cosmological observations provide a strong evidence that there is a positive cosmological constant in our universe and thus the spacetime is asymptotical de Sitter space. The conjecture of gravity as the weakest force in the asymptotical dS space leads to a lower bound on the U(1) gauge coupling $g$, or equivalently, the positive cosmological constant ge

Zhenjun Xiao, Fengying Li, Wenjuan Zou

In this paper, we study the upper bounds on the mass insertion parameters $(δ^{q}_{AB})_{ij}$ in the minimal supersymmetric standard model (MSSM). We found that the information from the measured branching ratio of $B \to X_s l^+ l^-$ decay can help us to improve the upper bounds on the mass insertions parameters $\left (δ^{u,d}_{AB})_{3j,i3}$. Some regions a

Subir Ghosh

A particular form of non-linear $σ$-model, having a global gauge invariance, is studied. The detailed discussion on current algebra structures reveals the non-abelian nature of the invariance, with {\it{field dependent structure functions}}. Reduction of the field theory to a point particle framework yields a non-linear harmonic oscillator, which is a specia

A. E. Shalyt-Margolin

In the present work the approach - density matrix deformation - earlier developed by the author to study a quantum theory of the Early Universe (Planck&#39;s scales) is applied to study a quantum theory of black holes. On this basis the author investigates the information paradox problem, entropy of the black hole remainders after evaporation, and consistenc

R. N. Mohapatra, A. Y. Smirnov

We review the present state of and future outlook for our understanding of neutrino masses and mixings. We discuss what we think are the most important perspectives on the plausible and natural scenarios for neutrinos and what may have the most promise to throw light on the flavor problem of quarks and leptons. We focus on the seesaw mechanism which fits int

Luigi Vezzoni

In this paper we give a generalization of the normal holomorphic frames in the symplectic manifolds and find conditions for the integrability of complex structures.

Payal Kaura, Aalok Misra, Pramod Shukla

Following [1] and [2], we discuss the Picard-Fuchs equation for the super Landau-Ginsburg mirror to the super-Calabi-Yau in WCP^(3|2)[1,1,1,3|1,5], (using techniques of [3,4]) Meijer basis of solutions and monodromies (at 0,1 and \infty) in the large and small complex structure limits, as well as obtain the mirror hypersurface, which in the large Kaehler lim

S. A. Mikhailov, N. A. Savostianova

Electromagnetic response of a finite-width two-dimensional electron stripe with attached metallic side contacts is theoretically studied. It is shown that contacts substantially influence the position, the linewidth, and the amplitude of plasmon-polariton resonances in the stripe. In finite magnetic fields, absorption of the wave with the inactive circular p

H. Sellier, G. P. Lansbergen, J. Caro, N. Collaert

We investigate by low-temperature transport experiments the sub-threshold behavior of triple-gate silicon field-effect transistors. These three-dimensional nano-scale devices consist of a lithographically defined silicon nanowire surrounded by a gate with an active region as small as a few tens of nanometers, down to 50x60x35 nm^3. Conductance versus gate vo

Massimo Pica Ciamarra, Antonio Coniglio, Mario Nicodemi

By detailed Molecular Dynamics and Monte Carlo simulations %of a realistic model we show that granular materials at rest can be described as thermodynamics systems. First we show that granular packs can be characterized by few parameters, as much as fluids or solids. Then, in a second independent step, we demonstrate that these states can be described in ter

John G. Hartnett, Michael E. Tobar

The 5D Cosmological General Relativity theory developed by Carmeli reproduces all of the results that have been successfully tested for Einstein&#39;s 4D theory. However the Carmeli theory because of its fifth dimension, the velocity of the expanding universe, predicts something different for the propagation of gravity waves on cosmological distance scales.