July 2006 arXiv papers — page 40

Michael Skeide

We show that every continuous product system of correspondences over a unital C*-algebra occurs as the product system of a strictly continuous E_0-semigroup.

Alexander Plakhov

A body moves in a medium composed of noninteracting point particles; interaction of particles with the body is absolutely elastic. It is required to find the body's shape minimizing or maximizing resistance of the medium to its motion. This is the general setting of optimal resistance problem going back to Newton. Here, we restrict ourselves to the two-d

Paolo Aluffi, Jean-Paul Brasselet

We give a short proof of the fact that the Chern classes for singular varieties defined by Marie-Helene Schwartz by means of "radial frames" agree with the functorial notion defined by Robert MacPherson.

Boris Chorny

Given a simplicial idempotent augmented endofunctor $F$ on a simplicial combinatorial model category $M$, under the assumption of Vopenka's principle, we exhibit a set $A$ of cofibrant objects in $M$ such that $F$ is equivalent to $\CW_A$, the cellularization with respect to $A$.

Said El Baghdadi, Stefania Gabelli

We extend to Prüfer $v$-multiplication domains some distinguished ring-theoretic properties of Prüfer domains. In particular we consider the $t##$-property, the $t$-radical trace property, $w$-divisoriality and $w$-stability.

Johan Jonasson

Recently Wilson [Ann. Appl. Probab. 14 (2004) 274--325] introduced an important new technique for lower bounding the mixing time of a Markov chain. In this paper we extend Wilson's technique to find lower bounds of the correct order for card shuffling Markov chains where at each time step a random card is picked and put at the top of the deck. Two classe

Yuri Kifer

We justify and give error estimates for binomial approximations of game (Israeli) options in the Black--Scholes market with Lipschitz continuous path dependent payoffs which are new also for usual American style options. We show also that rational (optimal) exercise times and hedging self-financing portfolios of binomial approximations yield for game options

Jose Blanchet, Peter Glynn

Consider a random walk $(S_n:n\geq0)$ with drift $-μ$ and $S_0=0$. Assuming that the increments have exponential moments, negative mean, and are strongly nonlattice, we provide a complete asymptotic expansion (in powers of $μ>0$) that corrects the diffusion approximation of the all time maximum $M=\max_{n\geq0}S_n$. Our results extend both the first-order co

Lothar Heinrich, Hendrik Schmidt, Volker Schmidt

We derive a central limit theorem for the number of vertices of convex polytopes induced by stationary Poisson hyperplane processes in $\mathbb{R}^d$. This result generalizes an earlier one proved by Paroux [Adv. in Appl. Probab. 30 (1998) 640--656] for intersection points of motion-invariant Poisson line processes in $\mathbb{R}^2$. Our proof is based on Ho

Luc Devroye, Hsien-Kuei Hwang

We propose a new, direct, correlation-free approach based on central moments of profiles to the asymptotics of width (size of the most abundant level) in some random trees of logarithmic height. The approach is simple but gives precise estimates for expected width, central moments of the width and almost sure convergence. It is widely applicable to random tr

Massimo Giulietti

All sets of lines providing a partition of the set of internal points to a conic C in PG(2,q), q odd, are determined. There exist only three such linesets up to projectivities, namely the set of all nontangent lines to C through an external point to C, the set of all nontangent lines to C through a point in C, and, for square q, the set of all nontangent lin

Boris Chorny, William G. Dwyer

Let $D$ be a large category which is cocomplete. We construct a model structure (in the sense of Quillen) on the category of small functors from $D$ to simplicial sets. As an application we construct homotopy localization functors on the category of simplicial sets which satisfy a stronger universal property than the customary homotopy localization functors

Jean-Baptiste Meilhan, Akira Yasuhara

A C_n-move is a local move on links defined by Habiro and Goussarov, which can be regarded as a `higher order crossing change'. We use Milnor invariants with repeating indices to provide several classification results for links up to C_n-moves, under certain restrictions. Namely, we give a classification up to C_4-moves of 2-component links, 3-component Brun

L. Barbieri-Viale, A. Bertapelle

We introduce the "sharp" (universal) extension of a 1-motive (with additive factors and torsion) over a field of characteristic zero. We define the "sharp de Rham realization" by passing to the Lie-algebra. Over the complex numbers we then show a (sharp de Rham) comparison theorem in the category of formal Hodge structures. For a free 1-motiv

Stephen Gustafson, Kyungkeun Kang, Tai-Peng Tsai

We present new interior regularity criteria for suitable weak solutions of the 3-D Navier-Stokes equations: a suitable weak solution is regular near an interior point $z$ if either the scaled $L^{p,q}_{x,t}$-norm of the velocity with $3/p+2/q\leq 2$, $1\leq q\leq \infty$, or the $L^{p,q}_{x,t}$-norm of the vorticity with $3/p+2/q\leq 3$, $1 \leq q < \infty$,

Friedrich Hubalek, Jan Kallsen, Leszek Krawczyk

We determine the variance-optimal hedge when the logarithm of the underlying price follows a process with stationary independent increments in discrete or continuous time. Although the general solution to this problem is known as backward recursion or backward stochastic differential equation, we show that for this class of processes the optimal endowment an

Laurent Denis, Claude Martini

The aim of this work is to evaluate the cheapest superreplication price of a general (possibly path-dependent) European contingent claim in a context where the model is uncertain. This setting is a generalization of the uncertain volatility model (UVM) introduced in by Avellaneda, Levy and Paras. The uncertainty is specified by a family of martingale probabi

Peter Brockwell, Erdenebaatar Chadraa, Alexander Lindner

A family of continuous-time generalized autoregressive conditionally heteroscedastic processes, generalizing the $\operatorname {COGARCH}(1,1)$ process of Klüppelberg, Lindner and Maller [J. Appl. Probab. 41 (2004) 601--622], is introduced and studied. The resulting $\operatorname {COGARCH}(p,q)$ processes, $q\ge p\ge 1$, exhibit many of the characteristic f

Panagiotis Stinis

In a recent paper \cite{CHSS06}, an infinitely long memory model (the t-model) for the Euler equations was presented and analyzed. The model can be derived by keeping the zeroth order term in a Taylor expansion of the memory integrand in the Mori-Zwanzig formalism. We present here a collection of models for the Euler equations which are based also on the Mor

Ser Peow Tan, Yan Loi Wong, Ying Zhang

We survey some of our recent results on length series identities for hyperbolic (cone) surfaces, possibly with cusps and/or boundary geodesics; classical Schottky groups; representations/characters of the one-holed torus group to $SL(2, \mathbf C)$; and hyperbolic 3 manifolds obtained by hyperbolic Dehn surgery on punctured torus bundles over the circle. The

Wladimir G. Boskoff, Bogdan D. Suceava

Barbilian spaces are metric spaces with a metric induced by a special procedure of metrization which is inspired by the study of the models of non-Euclidean geometry. In the present material we discuss the history of Barbilian spaces and the evolution of the theory. We point out that some of the current references to the work done in Barbilian spaces refer t

Xiangdong Xie

We show that if a domain D in a geodesic metric space is quasimobius to a uniform domain in some metric space, then D is also uniform.

Gautam Bharali

We begin with the following question: given a closed disc $\bar{D}$ in the complex plane and a complex-valued function F in $C(\bar{D})$, is the uniform algebra on $\bar{D}$ generated by z and F equal to $C(\bar{D})$ ? When F is in $C^1(\bar{D})$, this question is complicated by the presence of points in the surface S:=graph(F) that have complex tangents. Su

Alison Etheridge, Peter Pfaffelhuber, Anton Wakolbinger

For a genetic locus carrying a strongly beneficial allele which has just fixed in a large population, we study the ancestry at a linked neutral locus. During this ``selective sweep&#39;&#39; the linkage between the two loci is broken up by recombination and the ancestry at the neutral locus is modeled by a structured coalescent in a random background. For la

Ivan Marin

This work presents an approach towards the representation theory of the braid groups $B_n$. We focus on finite-dimensional representations over the field of Laurent series which can be obtained from representations of infinitesimal braids, with the help of Drinfeld associators. We set a dictionary between representation-theoretic properties of these two stru

Kenneth S. Alexander, Vladas Sidoravicius

We consider a polymer, with monomer locations modeled by the trajectory of a Markov chain, in the presence of a potential that interacts with the polymer when it visits a particular site 0. Disorder is introduced by, for example, having the interaction vary from one monomer to another, as a constant $u$ plus i.i.d. mean-0 randomness. There is a critical valu

Daniel Barlet, Morihiko Saito

We study the Brieskorn modules associated to a germ of holomorphic function with non-isolated singularities, and show that the Brieskorn module has naturally a structure of a module over the ring of microdifferential operators of nonpositive degree, and that the kernel of the morphism to the Gauss-Manin system coincides with the torsion part for the action o

Daniel Jafferis

We show that the index of BPS bound states of D4, D2 and D0 branes in IIA theory compactified on a toric Calabi Yau are encoded in the combinatoric counting of restricted three dimensional partitions. Using the torus symmetry, we demonstrate that the Euler character of the moduli space of bound states localizes to the number of invariant configurations that

Supriya Kar

We obtain dS and AdS generalized Reissner-Nordstrom like black hole geometries in a curved D3-brane frame-work, underlying a noncommutative gauge theory on the brane-world. The noncommutative scaling limit is explored to investigate a possible tunneling of an AdS vacuum in string theory to dS vacuum in its low energy gravity theory. The Hagedorn transition i

Aleksey Cherman, Thomas D. Cohen

In the large $N_c$ limit of QCD, baryons can be modeled as solitons, for instance, as Skyrmions. This modeling has been justified by Witten's demonstration that all properties of baryons and mesons scale with $N_c^{-1/2}$ in the same way as the analogous meson-based soliton model scales with a generic meson-meson coupling constant $g$. An alternative large $

Giuseppe Mussardo

In this paper we present an elementary derivation of the semi-classical spectrum of neutral particles in a field theory with kink excitations. In the non-integrable cases, we show that each vacuum state cannot generically support more than two stable particles, since all other neutral exitations are resonances, which will eventually decay. A phase space esti

G. Belanger, F. Boudjema, A. Pukhov, A. Semenov

micrOMEGAs2.0 is a code which calculates the relic density of a stable massive particle in an arbitrary model. The underlying assumption is that there is a conservation law like R-parity in supersymmetry which guarantees the stability of the lightest odd particle. The new physics model must be incorporated in the notation of CalcHEP, a package for the automa

R. Rattazzi

I review recent theoretical work on electroweak symmetry breaking.

Claude Duhr, Stefan Hoeche, Fabio Maltoni

Remarkable progress inspired by twistors has lead to very simple analytic expressions and to new recursive relations for multi-parton color-ordered amplitudes. We show how such relations can be extended to include color and present the corresponding color-dressed formulation for the Berends-Giele, BCF and a new kind of CSW recursive relations. A detailed com

R. Rattazzi

I give a pedagogical introduction to the concepts and the tools that are necessary to study particle physics models in higher dimensions. I then give a more detailed presentation of warped compactifications and discuss their possible relevance to the hierarchy problem.

Giulia Ricciardi

I discuss some aspects of the universality of soft gluon dynamics in semileptonic and radiative decays at the threshold region.

C. Wetterich

Antisymmetric tensor fields with chiral couplings to quarks and leptons may induce spontaneous electroweak symmetry breaking in a model without a ``fundamental&#39;&#39; Higgs scalar. No microscopic local mass term for the chiral tensors or ``chirons&#39;&#39; is allowed by the symmetries and our model exhibits only dimensionless couplings. However, the chir

Rajiv V. Gavai

I review a few selected topics in Lattice Quantum Chromo Dynamics, focusing more on the recent results. These include i) the equation of state and speed of sound, ii) J/ψsuppression, iii) flavour correlations and iv) the QCD phase diagram in the μ-T plane.

T. Hahn, J. I. Illana

Programming techniques which extend the capabilities of FeynArts and FormCalc are introduced and explained using examples from real applications.

M. I. Wanas, A. B. Morcos

In the present work, we prove the validity of two theorems on null-paths in a version of absolute parallelism geometry. A version of these theorems has been originally established and proved by Kermak, McCrea and Whittaker (KMW) in the context of Riemannian geometry. The importance of such theorems is their use, in applications, to derive a general formula f

Valerio Faraoni

The dynamical equivalence between modified and scalar-tensor gravity theories is revisited and it is concluded that it breaks down in the limit to general relativity. A gauge-independent analysis of cosmological perturbations in both classes of theories lends independent support to this conclusion. As a consequence, the PPN formalism of scalar-tensor gravity

Juan C. Valle-Lisboa, Eduardo Mizraji

Latent Semantic Analysis (LSA) is a well known method for information retrieval. It has also been applied as a model of cognitive processing and word-meaning acquisition. This dual importance of LSA derives from its capacity to modulate the meaning of words by contexts, dealing successfully with polysemy and synonymy. The underlying reasons that make the met

Aaron B. Wagner, Pramod Viswanath, Sanjeev R. Kulkarni

We consider the problem of estimating the total probability of all symbols that appear with a given frequency in a string of i.i.d. random variables with unknown distribution. We focus on the regime in which the block length is large yet no symbol appears frequently in the string. This is accomplished by allowing the distribution to change with the block len

Jan Chomicki

We present here a formal foundation for an iterative and incremental approach to constructing and evaluating preference queries. Our main focus is on query modification: a query transformation approach which works by revising the preference relation in the query. We provide a detailed analysis of the cases where the order-theoretic properties of the preferen

Anne-Marie Vercoustre, Mounir Fegas, Saba Gul, Yves Lechevallier

This paper reports on the INRIA group&#39;s approach to XML mining while participating in the INEX XML Mining track 2005. We use a flexible representation of XML documents that allows taking into account the structure only or both the structure and content. Our approach consists of representing XML documents by a set of their sub-paths, defined according to

Vinod Krishna

A first-principles treatment of the vibrational dynamics of molecular chemisorbates on metal surfaces is presented. It is shown that the mean field quantum evolution of the vibrational position operator is determined by a quantum Langevin equation with an electronic friction. In the mean field limit, the quantum noise and friction are related by the quantum

Yu. E. Kuzovlev

An one-dimensional model of magnetic flux penetration into thin strip-like superconductive film is subject to numerical analysis which combines explicit account for specific oblate geometry of magnetic field lines around the film and a simplest phenomenology of the flux flow resistance under rigid pinning of vortices with temperature-dependent critical curre

G. Chaudhuri, S. Das Gupta, M. Sutton

Consider a model of particles (nucleons) which has a two-body interaction which leads to bound composites with saturation properties. These properties are : all composites have the same density and the ground state energies of composites with k nucleons are given by -kW+σk^{2/3} where W and σare positive constants. W represents a volume term and σa surface t

K. Morimoto, Y. Itoh, K. Yoshimura, M. Kato

We report the magnetic susceptibility and NMR studies of a spin-gapped layered compound Na2Cu2TeO6 (the spin gap $Δ\sim$ 250 K), the hole doping effect on the Cu2TeO6 plane via a topochemical Na deficiency by soft chemical treatment, and the static spin vacancy effect by nonmagnetic impurity Zn substitution for Cu. A finite Knight shift at the $^{125}$Te sit

E. Granado, B. Uchoa, A. Malachias, R. Lora-Serrano

The magnetic structure and fluctuations of tetragonal GdRhIn5 were studied by resonant x-ray diffraction at the Gd LII and LIII edges, followed by a renormalization group analysis for this and other related Gd-based compounds, namely Gd2IrIn8 and GdIn3. These compounds are spin-only analogs of the isostructural Ce-based heavy-fermion superconductors. The gro

Yuhong Wang, Kapilanjan Krishan, Michael Dennin

We characterize the kinematics of bubbles in a sheared two-dimensional foam using statistical measures. We consider the distributions of both bubble velocities and displacements. The results are discussed in the context of the expected behavior for a thermal system and simulations of the bubble model. There is general agreement between the experiments and th

Stephen D. Wilson, Pengcheng Dai, Shiliang Li, Songxue Chi

In conventional superconductors, the interaction that pairs the electrons to form the superconducting state is mediated by lattice vibrations (phonons). In high-transition temperature (high-Tc) copper oxides, it is generally believed that magnetic excitations play a fundamental role in the superconducting mechanism because superconductivity occurs when mobil

J. S. Parker, D. E. Read, A. Kumar, P. Xiong

Superconducting quantum phase transitions tuned by disorder (d), paramagnetic impurity (MI) and perpendicular magnetic field (B) have been studied in homogeneously disordered ultrathin a-Pb films. The MI-tuned transition is characterized by progressive suppression of the critical temperature to zero and a continuous transition to a weakly insulating normal s

S. Sahrakorpi, Hsin Lin, R. S. Markiewicz, A. Bansil

We discuss doping dependencies of the electronic structure and Fermi surface of the monolayer Tl$_{2-x}$Cu$_x$Ba$_2$CuO$_{6+δ}$ (Tl2201). The TlO bands are found to be particularly sensitive to doping in that these bands rapidly move to higher energies as holes are added into the system. Such doping effects beyond the rigid band picture should be taken into

Ralf Brüning, Steve Emeneau, Kristopher Bulmer, Rabin Bissessur

A series of molybdenum disulfide intercalation compounds was prepared to study the effect of varying loadings of the samples with intercalated molecules. The molecules, (5,7,7,12,14,14-hexamethyl-1,4,8,11- tetraazacyclotetradeca-4,11-diene) macrocycles, occupy the gallery spaces between the MoS2 layers in a single layer. The samples were characterized by the

F. Pauly, M. Dreher, J. K. Viljas, M. Häfner

Conductance histograms are a valuable tool to study the intrinsic conduction properties of metallic atomic-sized contacts. These histograms show a peak structure, which is characteristic of the type of metal under investigation. Despite the enormous progress in the understanding of the electronic transport in metallic nanowires, the origin of this peak struc

Oleg Zaitsev

Recently semiclassical approximations have been successfully applied to study the effect of a superconducting lead on the density of states and conductance in ballistic billiards. However, the summation over classical trajectories involved in such theories was carried out using the intuitive picture of Andreev reflection rather than the semiclassical reasoni

A. N. Bogdanov, U. K. Roessler

It is shown that magnetic states and field-driven reorientation transitions in synthetic antiferromagnets crucially depend on contributions of higher-order anisotropies. A phenomenological macrospin model is derived to describe the magnetic states of two antiferromagnetically coupled magnetic thin film elements. The calculated phase diagrams show that magnet

D. J. Durian, H. Bideaud, P. Duringer, A. Schroder

The shapes of flat pebbles may be characterized in terms of the statistical distribution of curvatures measured along their contours. We illustrate this new method for clay pebbles eroded in a controlled laboratory apparatus, and also for naturally-occurring rip-up clasts formed and eroded in the Mont St.-Michel bay. We find that the curvature distribution a

J. T. Devreese

An overview is presented of the fundamentals of continuum-polaron physics, which provide the basis of the analysis of polaron effects in ionic crystals and polar semiconductors. The present paper deals with &#34;large&#34;, or &#34;continuum&#34;, polarons, as described by the Froehlich Hamiltonian. The emphasis is on the polaron optical absorption.

Sadhan K. Adhikari

We use a time-dependent dynamical mean-field-hydrodynamic model to study mixing-demixing in a degenerate fermion-fermion mixture (DFFM). It is demonstrated that with the increase of interspecies repulsion and/or trapping frequencies, a mixed state of DFFM could turn into a fully demixed state in both three-dimensional spherically-symmetric as well as quasi-o

M. J. Greenall, Th. Voigtmann

We report idealized mode-coupling theory results for the glass transition of ensembles of model fullerenes interacting via phenomenological two-body potentials. Transition lines are found for C60, C70 and C96 in the temperature-density plane. We argue that the observed glass-transition behavior is indicative of kinetic arrest that is strongly driven by the i

Kristan Temme, Thomas Gasenzer

The dynamical evolution of a Bose-Einstein condensate trapped in a one-dimensional lattice potential is investigated theoretically in the framework of the Bose-Hubbard model. The emphasis is set on the far-from-equilibrium evolution in a case where the gas is strongly interacting. This is realized by an appropriate choice of the parameters in the Hamiltonian

R. Mathieu, M. Uchida, Y. Kaneko, J. P. He

Phase diagrams in the plane of $r_A$ (the average ionic radius, related to one-electron bandwidth $W$) and $σ^2$ (the ionic radius variance, measuring the quenched disorder), or ``bandwidth-disorder phase diagrams&#39;&#39;, have been established for perovskite manganites, with three-dimensional (3$D$) Mn-O network. Here we establish the intrinsic bandwidth-

Tristan Baumberger, Christiane Caroli, David Martina

We present an extensive experimental study of mode-I, steady, slow crack dynamics in gelatin gels. Taking advantage of the sensitivity of the elastic stiffness to gel composition and history we confirm and extend the model for fracture of physical hydrogels which we proposed in a previous paper (Nature Materials, doi:10.1038/nmat1666 (2006)), which attribute

C. M. Horowitz, C. R. Proetto, S. Rigamonti

The behavior of the surface barrier that forms at the metal-vacuum interface is important for several fields of surface science. Within the Density Functional Theory framework, this surface barrier has two non-trivial components: exchange and correlation. Exact results are provided for the exchange component, for a jellium metal-vacuum interface, in a slab g

S. Amasha, K. MacLean, Iuliana Radu, D. M. Zumbuhl

We measure the relaxation rate $W \equiv T_{1}^{-1}$ of a single electron spin in a quantum dot at magnetic fields from 7 T down to 1.75 T, much lower than previously measured. At 1.75 T we find that $T_{1}$ is 170 ms. We find good agreement between our measurements and theoretical predictions of the relaxation rate caused by the spin-orbit interaction, demo

V. Sokolovsky, V. Meerovich

The stationary thermal state and propagation of a normal zone in a long superconducting film on a wide substrate are analyzed analytically. Expressions describing voltage-current characteristics and temperature-current dependence of the film are derived for the flux creep, flux flow and normal regions. It is shown how the flux creep influences the conditions

Sylvain Bertaina, Roland Hayn

Estimating the intrachain and interchain exchange constants in BaCu2X2O7 (X=Ge,Si) by means of density-functional calculations within the local spin-density approximation (LSDA) we find the Ge compound to be a more ideal realization of a one-dimensional spin chain with Dzyaloshinskii-Moriya interaction than its Si counterpart. Both compounds have a comparabl

P. -M. König, R. Roth, S. Dietrich

We extend the insertion approach for calculating depletion potentials to the case of non-spherical solutes. Instead of a brute-force calculation we suggest to employ the recently developed curvature expansion of density profiles close to complexly shaped walls. The approximations introduced in the calculation by the use of the curvature expansion and of weig

Fabio Cecconi, Carlo Guardiani, Roberto Livi

The WW domain of the human Pin1 protein for its simple topology and the large amount of experimental data is an ideal candidate to assess theoretical approaches to protein folding. The purpose of the present work is to compare the reliability of the chemically-based Sorenson/Head-Gordon (SHG) model and a standard native centric model in reproducing through m

Hiroaki Onishi, Takashi Hotta

We investigate the ground-state property of a one-dimensional two-orbital Hubbard model at quarter filling by numerical techniques such as the density-matrix renormalization group method and the exact diagonalization. When the Hund&#39;s rule coupling $J$ is zero, the model is SU(4) symmetric. In fact, both spin and orbital correlations have a peak at $q=π/2

Marlan O. Scully, Anatoly A. Svidzinsky

A nonequilibrium master equation analysis for N interacting bosons, with Bogoliubov quasiparticles as the reservoir is presented. The analysis is based on a simplified Hamiltonian. The steady state solution yields the equilibrium density matrix. The results are in good agreement with and extend our previous rigorous canonical ensemble equilibrium statistical

Zhi-Ming Gu, Ming Zhao, Tao Zhou, Chen-Ping Zhu

In this paper, by extending the concept of Kuramoto oscillator to the left-invariant flow on general Lie group, we investigate the generalized phase synchronization on networks. The analyses and simulations of some typical dynamical systems on Watts-Strogatz networks are given, including the $n$-dimensional torus, the identity component of 3-dimensional gene

S. Urayama, T. Hatano, H. B. Wang, M. Nagao

To investigate in-phase structures (rectangular lattice) of Josephson vortex lattice (JVL) in intrinsic Josephson junctions (IJJs) of Bi2Sr2CaCu2O8+d, we fabricated IJJs with various lateral sizes down to a size of non-linear core of Josephson vortex using focused-ion-beam etching and measured flux flow resistance (RFF) with in-plane magnetic fields (H). We

K. Sengupta, S. V. Isakov, Yong Baek Kim

We study the superfluid-insulator transitions of bosons on the Kagome lattice at incommensurate filling factors f=1/2 and 2/3 using a duality analysis. We find that at f=1/2 the bosons will always be in a superfluid phase and demonstrate that the T_3 symmetry of the dual (dice) lattice, which results in dynamic localization of vortices due to the Aharanov-Bo

M. Volonteri, M. J. Rees

The Sloan Digital Sky survey detected luminous quasars at very high redshift, z>6. Follow-up observations indicated that at least some of these quasars are powered by supermassive black holes (SMBHs) with masses in excess of billion solar masses. SMBHs, therefore, seem to have already existed when the Universe was less than 1 Gyr old, and the bulk of galaxy

Sidney van den Bergh

The satellite systems of M31 and the Galaxy are compared. It is noted that all five of the suspected stripped dSph cores of M31 companions are located within a projected distance of 40 kpc of from the nucleus of this galaxy, whereas the normal dSph companions to this object have distances > 40 kpc from the center of M31. All companions within 200 kpc < D(M31

Michael H. Siegel

We present a catalog of 15 RR Lyrae variable stars in the recently discovered Bootes galaxy -- the most metal-poor simple stellar population with measured RR Lyrae stars. The pulsational properties of the RR Lyrae conform closely to period-abundance trends extrapolated from more metal-rich populations and we estimate the distance of Bootes to be (m-M)_0=18.9

Michael H. Siegel, Howard E. Bond

Insight into the origin of unusual events like the eruption of V838 Mon can be obtained from studies of the stellar populations from which they arise. V838 Mon lies in an intriguing region of the Galaxy, toward the warped outer edge of the disk, with significant contributions from the Galactic thick disk and the recently discovered Monoceros tidal stream. Th

L. J. Hainline, A. W. Blain, T. R. Greve, S. C. Chapman

We report the first detection of CO(1-0) emission from a submillimeter-selected galaxy, using the Green Bank Telescope. We identify the line in the spectrum of SMM J13120+4242 as a broad emission feature at z=3.408, with Delta(V_FWHM)=1040 +/- 190 km/s. If the observed CO(1-0) line profile arises from a single object and not several merging objects, then the

Elizabeth H. Wehner, John S. Gallagher, Polichronis Papaderos, Uta Fritze-von Alvensleben

NGC 3310 is a local galaxy with an intense, ongoing starburst thought to result from a merger with a companion galaxy. It has several known tidal features in the northwest and southern regions around the main galactic disc, as well as a closed, tidal loop emerging from the eastern side of the disc and rejoining in the north. This loop appears to be distinct

Misty C. Bentz, Kelly D. Denney, Edward M. Cackett, Matthias Dietrich

We have undertaken a new ground-based monitoring campaign to improve the estimates of the mass of the central black hole in NGC 4151. We measure the lag time of the broad H beta line response compared to the optical continuum at 5100 A and find a lag of 6.6 (+1.1/-0.8) days. We combine our data with the recent reanalysis of UV emission lines by Metzroth et a

M. P. Muno, J. Mauerhan

We report the discovery of excess 4.5 and 8 micron emission from three quiescent black hole low-mass X-ray binaries, A 0620-00, GS 2023+338, and XTE J1118+480. The mid-infrared emission from GS 2023+338 probably originates in the accretion disk. However, the excess emission from A 0620-00 and XTE J1118+480 is brighter and peaks at longer wavelengths, and so

W. Becker, C. Y. Hui, B. Aschenbach, A. Iyudin

The properties of the presumably young galactic supernova remnant (SNR) RX J0852.0-4622, discovered by ROSAT, are still uncertain. The data concerning the distance to the SNR, its age, and the presence of a compact remnant remain controversial. We report the results of several XMM-Newton observations of CXOU J085201.4-461753, the central compact source in RX

Steven J. Berukoff, Bradley M. S. Hansen

We present results of N-body simulations aimed at understanding the dynamics of young stars near the Galactic center. Specifically, we model the inspiral of a cluster core containing an intermediate mass black hole and $N \sim 50$ cluster stars in the gravitational potential of a supermassive black hole. We first study the elliptic three-body problem to isol

T. P. Krichbaum, D. A. Graham, A. Witzel, J. A. Zensus

We report on new developments in VLBI, with emphasis on experiments performed at the highest frequencies possible to date (so called mm-VLBI). We have observed the nucleus of M 87 (Virgo A) with global VLBI at 3 mm. We show a new image of the inner-most jet region with an angular resolution of approx. 300 x 60 micro-arcseconds. In terms of Schwarzschild radi

Y. C. Liang, S. Y. Yin, F. Hammer, L. C. Deng

Using a large sample of 38,478 star-forming galaxies selected from the Second Data Release of the Sloan Digital Sky Survey database (SDSS-DR2), we derive analytical calibrations for oxygen abundances from several metallicity-sensitive emission-line ratios: [N II]/H_alpha, [O III]/[N II], [N II]/[O II], [N II]/[S II], [S II]/H_alpha, and [O III]/H_beta. This

S. Colafrancesco, S. Profumo, P. Ullio

We explore the possible signatures of dark matter (DM) pair annihilations in the nearby dwarf spheroidal galaxy Draco. After investigating the mass models for Draco in the light of available observational data, we carefully model the DM density profile, taking advantage of numerical simulations of hierarchical structure formation. We then analyze the gamma-r

T. P. Krichbaum, D. A. Graham, M. Bremer, W. Alef

We present and discuss new result from mm-VLBI observations of M87 and SgrA*, using the Global mm-VLBI array (GMVA). New 3mm-VLBI images of the inner jet of M87 are presented, showing details with a spatial resolution down to 15 Schwarzschild radii. This resolution corresponds to a similar spatial resolution (in terms of R_s) obtained for Sgr A*. We discuss

Ann B. Kapusta, John R. Thorstensen

We report spectroscopy of the newly discovered SU Ursae Majoris dwarf nova identified with the x-ray source RXS J053234.9+624755. Radial velocities of the H-alpha emission line in the quiescent state give an orbital period of 0.05620(4) d (80.93 min), which is among the shortest for SU UMa stars with determined periods. We also report UBVI magnitudes of the

M. J. Koop, R. B. Mann

We investigate the equal-mass 3-body system in general relativistic lineal gravity in the presence of a cosmological constant $Λ$. The cosmological vacuum energy introduces features that do not have a non-relativistic counterpart, inducing a competing expansion/contraction of spacetime that competes with the gravitational self-attraction of the bodies. We de

J. Dewi

CXOU J121538.2+361921 is the brightest X-ray source in the galaxy NGC 4214, with an X-ray luminosity of up to 0.7 x 10^39 erg/s. The observed periodicity of 3.62 hr is interpreted as the orbital period of the system. It has been suggested that the system is a low-mass helium star with a lower-mass compact companion. If this idea is correct, then CXOU J121538

Michael D. Audley, Robert W. Barker, Michael Crane, Roger Dace

CLOVER is an experiment which aims to detect the signature of gravitational waves from inflation by measuring the B-mode polarization of the cosmic microwave background. CLOVER consists of three telescopes operating at 97, 150, and 220 GHz. The 97-GHz telescope has 160 horns in its focal plane while the 150 and 220-GHz telescopes have 256 horns each. The hor

Roberto Trotta, Richard Bower

We examine the prospects for the next generation of surveys aimed at elucidating the nature of dark energy. We review the methods that can be used to determine the redshift evolution of the dark energy equation of state parameter w, highlighting their respective strengths and potential weaknesses. All of the attractive methods require surveys covering more t

Masaaki Kusunose, Fumio Takahara

The emission spectra of TeV blazars extend up to tens of TeV and the emission mechanism of the TeV $γ$-rays is explained by synchrotron self-Compton scattering in leptonic models. In these models the time variabilities of X-rays and TeV $γ$-rays are correlated. However, recent observations of 1ES 1959+650 and Mrk 421 have found the ``orphan&#39;&#39; TeV $γ$

M. -R. L. Cioni, L. Girardi, P. Marigo, H. J. Habing

This article compares the distribution of Ks magnitude of Large Magellanic Cloud (LMC) asymptotic giant branch (AGB) stars obtained from the DENIS and 2MASS data with theoretical distributions. These have been constructed using up-to-date stellar evolution calculations for low and intermediate-mass stars, and in particular for thermally pulsing AGB stars. A

L. Freidel, J. Kowalski--Glikman, A. Starodubtsev

Since the work of Mac-Dowell-Mansouri it is well known that gravity can be written as a gauge theory for the de Sitter group. In this paper we consider the coupling of this theory to the simplest gauge invariant observables that is, Wilson lines. The dynamics of these Wilson lines is shown to reproduce exactly the dynamics of relativistic particles coupled t

Y. Aoki, C. Dawson, J. Noaki, A. Soni

Hadronic matrix elements of operators relevant to nucleon decay in grand unified theories are calculated numerically using lattice QCD. In this context, the domain-wall fermion formulation, combined with non-perturbative renormalization, is used for the first time. These techniques bring reduction of a large fraction of the systematic error from the finite l

Sungwook Lee

It is shown that timelike surfaces of constant mean curvature 1 in anti-de Sitter 3-space can be constructed from a pair of Lorentz holomorphic and Lorentz antiholomorphic null curves in PSL(2,R) via Bryant type representation formulae. These formulae are used to investigate an explicit one-to-one correspondence, the so-called Lawson correspondence, between