July 2005 arXiv papers — page 6

Adam Paszkiewicz

We characterize sequences of numbers $(a_n)$ such that $\sum_{n\geq 1} a_nΦ_n$ converges a.e. for any orthonormal system $(Φ_n)$ in any $L_2$-space. In our criterion, we use the set $B =\{\sum_{m\geq n} |a_m|^2; n\geq 1\}$ and its information function $$h_B(t) = -\log_3(β-α)$$ for $t\in (α, β]$, $[α, β]\cap B =\{α, β\}.$

Sergei V. Gusev, Igor A. Makarov

The paper considers a motion control problem for kinematic models of nonholonomic wheeled systems. The class of maneuverable wheeled systems is defined consisting of systems that can follow any sufficiently smooth non-stop trajectory on the plane. A sufficient condition for maneuverability is obtained. The design of control law that stabilizes motion along t

Gregory J. Morrow, Yu Zhang

Let L_n denote the lowest crossing of the 2n \times 2n square box B(n) centered at the origin for critical site percolation on Z^2 or critical site percolation on the triangular lattice imbedded in Z^2, and denote by Q_n the set of pivotal sites along this crossing. On the event that a pivotal site exists, denote the minimum height that a pivotal site attain

Eric Babson, Isabella Novik, Rekha R. Thomas

A short new proof of the fact that all shifted complexes are fixed by reverse lexicographic shifting is given. A notion of lexicographic shifting, $Δ_{\lex}$ -- an operation that transforms a monomial ideal of $S=\field[x_i: i\in\N]$ that is finitely generated in each degree into a squarefree strongly stable ideal -- is defined and studied. It is proved that

Scott Baldridge, Paul Kirk

In this paper we construct a family of symplectic 4--manifolds with positive signature for any given fundamental group $G$ that approaches the BMY line. The family is used to show that one cannot hope to do better than than the BMY inequality in finding a lower bound for the function $f=χ+bσ$ on the class of all minimal symplectic 4-manifolds with a given fu

Tristram Bogart, Anders Jensen, David Speyer, Bernd Sturmfels

The tropical variety of a $d$-dimensional prime ideal in a polynomial ring with complex coefficients is a pure $d$-dimensional polyhedral fan. This fan is shown to be connected in codimension one. We present algorithmic tools for computing the tropical variety, and we discuss our implementation of these tools in the Gr\"obner fan software \texttt{Gfan}. Ever

Michel Deza, Mathieu Dutour, Mikhail Shtogrin

We consider the following generalization of the decomposition theorem for polycycles. A {\em $(R,q)$-polycycle} is, roughly, a plane graph, whose faces, besides some disjoint {\em holes}, are $i$-gons, $i \in R$, and whose vertices, outside of holes, are $q$-valent. Such polycycle is called {\em elliptic}, {\em parabolic} or {\em hyperbolic} if $\frac{1}{q}

Yahya Ould Hamidoune, Oriol Serra, Gilles Zemor

Let A and B be subsets of Z/pZ such that |A+B| < |A|+|B|+2. We prove that, if |A|>3, |B|>4, |A+B|<p-4 and p > 52, then A and B are included in arithmetic progressions with the same difference and of size |A|+2 and |B|+2 respectively. This extends the well-known theorem of Vosper and a recent result of Rodseth and one of the present authors.

Ioan Bucataru

Consider $L$ a regular Lagrangian, $S$ the canonical semispray, and $h$ the horizontal projector of the canonical nonlinear connection. We prove that if the Lagrangian is constant along the integral curves of the Euler-Lagrange equations then it is constant along the horizontal curves of the canonical nonlinear connection. In other words $S(L)=0$ implies $d_

J. Carlos Diaz-Ramos, Eduardo Garcia-Rio, Ramon Vazquez-Lorenzo

A complete description of Osserman four-manifolds whose Jacobi operators have a nonzero double root of the minimal polynomial is given.

M. Brozos-Vazquez, P. Gilkey

We characterize Riemannian manifolds of constant sectional curvature in terms of commutation properties of their Jacobi operators.

Alison E. Parker

Let G be a linear algebraic group over an algebraically closed field of characteristic p whose corresponding root system is irreducible. In this paper we calculate the Weyl filtration dimension of the induced G-modules, \nabla(λ) and the simple G-modules L(λ), for λa regular weight. We use this to calculate some Ext groups of the form Ext^*(\nabla(λ),Δ(μ)),

K. R. Goodearl, E. S. Letzter

In previous work, the second author introduced a topology, for spaces of irreducible representations, that reduces to the classical Zariski topology over commutative rings but provides a proper refinement in various noncommutative settings. In this paper, a concise and elementary description of this refined Zariski topology is presented, under certain hypoth

J. A. Arteaga, M. A. Malakhaltsev

We prove that the Ricci flow equation for left invariant metrics on Lie groups reduces to a first order ordinary differential equation for a map $Q : (-a,a) \to UT$, where $UT$ is the group of upper triangular matrices. We decompose the matrix $R_{ij}$ of Ricci tensor coordinates with respect to an orthonormal frame field $E_{i}$ into a sum $\overset{1}{R}_{

Hisanobu Shinya

The paper was withdrawn by the author. It contained various errors.

Mark Kambites

We consider blind, deterministic, finite automata equipped with a register which stores an element of a given monoid, and which is modified by right multiplication by monoid elements. We show that, for monoids M drawn from a large class including groups, such an automaton accepts the word problem of a group H if and only if H has a finite index subgroup whic

Juergen Klueners

We prove that the number of quartic $S_4$--extensions of the rationals of given discriminant $d$ is $O_\eps(d^{1/2+\eps})$ for all $\eps>0$. For a prime number $p$ we derive that the dimension of the space of octahedral modular forms of weight 1 and conductor $p$ or $p^2$ is bounded above by $O(p^{1/2}\log(p)^2)$.

Matthew Baker, Robert Rumely

We study the Laplacian on a metrized graph, and its eigenfunctions.

Matthew Baker, Robert Rumely

If phi(z) is a rational function on P^1 of degree at least 2 with coefficients in a number field k, we compute the homogeneous transfinite diameter of the v-adic filled Julia sets of phi for all places v of k by introducing a new quantity called the homogeneous sectional capacity. In particular, we show that the product over all places of these homogeneous t

Achill Schuermann, Frank Vallentin

We describe algorithms which address two classical problems in lattice geometry: the lattice covering and the simultaneous lattice packing-covering problem. Theoretically our algorithms solve the two problems in any fixed dimension d in the sense that they approximate optimal covering lattices and optimal packing-covering lattices within any desired accuracy

Piotr T. Chrusciel, Erwann Delay, John M. Lee, Dale N. Skinner

We show that C^2 conformally compact Riemannian Einstein metrics have conformal compactifications that are smooth up to the boundary in dimension 3 and all even dimensions, and polyhomogeneous in odd dimensions greater than 3.

G. Duffy, C. Harris, P. Kanti, E. Winstanley

In this work, we study the `scalar channel&#39; of the emission of Hawking radiation from a (4+n)-dimensional, rotating black hole on the brane. We numerically solve both the radial and angular part of the equation of motion for the scalar field, and determine the exact values of the absorption probability and of the spheroidal harmonics, respectively. With

Stefano Bolognesi

We present a new vortex solution made of a domain wall compactified into a cylinder and stabilized by the magnetic flux within. When the thickness of the wall is much less than the radius of the vortex some precise results can be obtained, such as the tension spectrum and profile functions. This vortex can naturally end on the wall that has created it, makin

Th. M. Nieuwenhuizen, I. V. Volovich

In a recent paper Hawking has argued that there is no information loss in black holes in asymptotically AdS spacetimes. We remind that there are several types of information (entropy) in statistical physics -- fine grained (microscopic) and coarse grained (macroscopic) ones which behave differently under unitary evolution. We suggest that the coarse grained

Piero Nicolini

The phenomenology of a radiating Schwarzschild black hole is analyzed in a noncommutative spacetime. It is shown that noncommutativity does not depend on the intensity of the curvature. Thus we legitimately introduce noncommutativity in the weak field limit by a coordinate coherent state approach. The new interesting results are the following: i) the existen

Nobuyuki Ishibashi, Tsunehide Kuroki, Atsushi Yamaguchi

Nonperturbative effects in c<1 noncritical string theory are studied using the two-matrix model. Such effects are known to have the form fixed by the string equations but the numerical coefficients have not been known so far. Using the method proposed recently, we show that it is possible to determine the coefficients for (p,q) string theory. We find that th

Stoytcho S. Yazadjiev

We systematically derive the asymptotically flat five dimensional black rings in EMd gravity by using the sigma model structure of the dimensionally reduced field equations. New non-asymptotically flat EMd black ring solutions in five dimensions are also constructed and their physical properties are analyzed.

F. T. Brandt, F. A. Chishtie, D. G. C. McKeon

The effective potential $V$ is considered in massless $λϕ^4_4$ theory. The expansion of $V$ in powers of the coupling $λ$ and of the logarithm of the background field $ϕ$ is reorganized in two ways; first as a series in $λ$ alone, then as a series in $\lnϕ$ alone. By applying the renormalization group (RG) equation to $V$, these expansions can be summed. Usi

Bhaskar Dutta, Yukihiro Mimura, R. N. Mohapatra

During the past year, a minimal renormalizable supersymmetric SO(10) model has been proposed with the following properties: it predicts a naturally stable dark matter and neutrino mixing angles theta_atm and theta_13 while at the same time accommodating CKM CP violation among quarks with no SUSY CP problem. Suppression of proton decay for all allowed values

Peter Petreczky, Derek Teaney

We study the diffusion of heavy quarks in the Quark Gluon Plasma using the Langevin equations of motion and estimate the contribution of the transport peak to the Euclidean current-current correlator. We show that the Euclidean correlator is remarkably insensitive to the heavy quark diffusion coefficient and give a simple physical interpretation of this resu

Richard J. Gonsalves, Nikolaos Kidonakis, Agustin Sabio Vera

We study the production of W bosons at large transverse momentum in pp collisions at the Large Hadron Collider (LHC). We calculate the complete next-to-leading order (NLO) corrections to the differential cross section. We find that the NLO corrections provide a large increase to the cross section but, surprisingly, do not reduce the scale dependence relative

D. Anchishkin, R. Naryshkin

We revise the pion-pion and quark-quark annihilation mechanisms of dilepton production during relativistic heavy-ion collisions. We focus on the modifications caused by the specific features of intramedium pion states rather than by medium modification of the rho-meson spectral density. The main ingredient emerging in our approach is a form-factor of the mul

Amitava Datta, Jyoti Prasad Saha, Anirban Kundu, Abhijit Samanta

Within the framework of R-parity violating minimal supergravity model, at least three relatively large lepton-number violating $ł&#39;$ type trilinear couplings at the GUT scale, not directly related to neutrino physics, can naturally generate via renormalization group (RG) evolution and/or CKM rotation the highly suppressed bilinear and trilinear parameters

Benjamin Portheault

Using deep inelastic $e^{\pm}p$ charged and neutral current scattering cross sections previously published, a combined electroweak and QCD analysis is performed to determine electroweak parameters accounting for their correlation with parton distributions. The data used have been collected by the H1 experiment in 1994-2000 and correspond to an integrated lum

Charles D. Lane

We analyze Doppler-effect experiments in terms of a general framework for violations of Lorentz symmetry: the Standard-Model Extension. These experiments are found to be sensitive to heretofore unprobed combinations of Lorentz-violation coefficients associated with protons and electrons. New bounds at the level of $10^{-11}$ and $10^{-8}$ for proton coeffici

M. Matsumori, A. I. Sanda, Y. -Y. Keum

The radiative B -> K* gamma mode is caused by a penguin operator which is a quantum correction. Thus this mode may be useful in the search for physics beyond the standard model. In this paper, we compute the branching ratio, direct CP asymmetry, and isospin breaking effects within the Standard Model in the framework perturbative QCD, and discuss how new phys

CDF Collaboration, A. Abulencia

A search for new particles (X) that decay to electron or muon pairs has been performed using approximately 200 pb**(-1) of pbarp collision data at sqrt(s)=1.96 TeV collected by the CDF II experiment at the Fermilab Tevatron. Limits on sigma(ppbar -> X)*BR(X -> ll) are presented as a function of dilepton invariant mass m(ll) > 150 GeV/c**2, for different spin

J. M. Link

We apply a genetic programming technique to search for the double Cabibbo suppressed decays $Λ_c^+ \to p K^+ π^-$ and $D_s^+ \to K^+ K^+ π^-$. We normalize these decays to their Cabibbo favored partners and find $\text{BR}($Λ_c^+ \to p K^+ π^-$)/\text{BR}($Λ_c^+ \to p K^- π^+$) = (0.05 \pm 0.26 \pm 0.02)%$ and $\text{BR}($D_s^+ \to K^+ K^+ π^-$)/\text{BR}($D

Daniel Wicke

The heaviest known Fermion particle -- the top quark -- was discovered at Fermilab in the first run of the Tevatron in 1995. However, besides its mere existence one needs to study its properties precisely in order to verify or falsify the predictions of the Standard Model. With the top quark&#39;s extremely high mass and short lifetime such measurements prob

B. Aubert, BABAR Collaboration

We present a measurement of the Cabibbo-Kobayashi-Maskawa CP-violating phase gamma with a Dalitz plot analysis of neutral D-meson decays to the Ks pi- pi+ final state from B-+ -> D(*) K-+ and B-+ -> D K*-+ decays, using a sample of 227 million BBbar pairs collected by the BaBar detector. We measure gamma = 67 +/- 28 +/- 13 +/- 11, where the first error is st

M. Ablikim

Using 58 million J/ψevents accumulated with the BES II detector, branching fractions for the η_{c} ->VV decays, η_{c} -> ρρ, η_{c} -> K^{*}{\bar K}^{*}, η_{c} -> ωω, and η_{c} -> ϕϕ, are measured. The branching fractions are Br(η_{c} -> ρρ) = (1.25 \pm 0.37 \pm 0.51) \times 10^{-2}, Br(η_{c} -> \K^{*}{\bar K}^{*}) = (10.4 \pm 2.6\pm 4.3) \times 10^{-3}, Br(η

Gavin Duffy, Adrian C. Ottewill

We show that the pathology which afflicts the Hartle-Hawking vacuum on the Kerr black hole space-time can be regarded as due to rigid rotation of the state with the horizon in the sense that when the region outside the speed-of-light surface is removed by introducing a mirror, there is a state with the defining features of the Hartle-Hawking vacuum. In addit

Sunder Lal, Atul Chaturvedi

In this paper we proposed two identification schemes based on the root problem. The proposed schemes are secure against passive attacks assuming that the root problem (RP) is hard in braid groups.

Zengyou He, Xiaofei Xu, Shengchun Deng

The task of outlier detection is to find small groups of data objects that are exceptional when compared with rest large amount of data. In [38], the problem of outlier detection in categorical data is defined as an optimization problem and a local-search heuristic based algorithm (LSA) is presented. However, as is the case with most iterative type algorithm

Gleb Yakovlev, John B. Rundle, Robert Shcherbakov, Donald L. Turcotte

We derive an analytical expression of the inter-arrival time distribution for a non-homogeneous Poisson process (NHPP). This expression is exact and is applicable to any time interval, finite or infinite. As an illustration, we present simulation results for three different intensity functions.

Péter Major, V. M. García-Suárez, S. Sirichantaropass, József Cserti

We propose a mixed analytical-ab-initio method for the accurate calculation of the conductance in monovalent atomic wires. The method relies on the most general formula for ballistic transport through a monovalent wire, whose parameters can be determined from first-principles calculations. Our central result is the demonstration of the highly non-universal b

Tonica Valla

Recent observation of a &#34;kink&#34; in single-particle dispersion in photoemission experiments on cuprate superconductors has initiated a heated debate over the issue of a boson that mediates the pairing in cuprates. If the &#34;kink&#34; is indeed caused by interaction with a bosonic excitation, then there are two possible candidates: phonons and spin fl

S. K. Chen, K. A. Yates, M. G. Blamire, J. L. MacManus-Driscoll

The influence of the nature of the boron precursor on the superconducting properties of polycrystalline MgB2 was studied. Critical current densities for the MgB2 made from high purity amorphous boron are at least a factor of three higher than typical values measured for standard MgB2 samples made from amorphous precursors. Two possible mechanisms are propose

Zhenyu Li, D. S. Kosov

We present a plane wave/pseudopotential implementation of the method to calculate electron transport properties of nanostructures. The conductance is calculated via the Landauer formula within formalism of Green&#39;s functions. Nonorthogonal Wannier-type atomic orbitals are obtained by the sequential unitary rotations of virtual and occupied Kohn-Sham orbit

C. Beisbart, M. S. Barbosa, H. Wagner, L. da F. Costa

Minkowski valuations provide a systematic framework for quantifying different aspects of morphology. In this paper we apply vector- and tensor-valued Minkowski valuations to neuronal cells from the cat&#39;s retina in order to describe their morphological structure in a comprehensive way. We introduce the framework of Minkowski valuations, discuss their impl

Mikael Fogelstrom, Tomas Lofwander

The thermoelectric coefficient $η(T)$ in unconventional superconductors is enhanced below $T_c$ by intermediate strength impurity scattering that is intrinsically particle-hole asymmetric. We compute $η(T)$ for a strong-coupling d-wave superconductor and investigate the effects of inelastic scattering originating from electron-boson interactions. We show tha

M. P. Blencowe, J. Imbers, A. D. Armour

We present an analysis of the dynamics of a nanomechanical resonator coupled to a superconducting single electron transistor (SSET) in the vicinity of the Josephson quasiparticle (JQP) and double Josephson quasiparticle (DJQP) resonances. For weak coupling and wide separation of dynamical timescales, we find that for either superconducting resonance the dyna

F. Caruso, V. Latora, A. Rapisarda, B. Tadic

We study the effects of the topology on the Olami-Feder-Christensen (OFC) model, an earthquake model of self-organized criticality. In particular, we consider a 2D square lattice and a random rewiring procedure with a parameter $0<p<1$ that allows to tune the interaction graph, in a continuous way, from the initial local connectivity to a random graph. The m

Mathias Michel, Jochen Gemmer, Guenter Mahler

We consider chains consisting of several identical subsystems weakly coupled by various types of next neighbor interactions. At both ends the chain is coupled to a respective heat bath with different temperature modeled by a Lindblad formalism. The temperature gradient introduced by this environment is then treated as an external perturbation. We propose a m

Nada Joo, Pascale Auban-Senzier, Claude Pasquier, Denis Jérome

The study of the anion ordered (TMTSF)\_2ClO\_4\_(1-x)ReO\_4\_x, solid solution in the limit of a low ReO\_4- substitution level (0<=x<=17%) has revealed a new and interesting phase diagram. Superconductivity is drastically suppressed as the effect of ReO\_4- non magnetic point defects increases following the digamma behaviour for usual superconductors in th

S. Chakraverty, M. Bandyopadhyay

A typical coercivity versus particle size curve for magnetic nanoparticles has been explained by using the Gilbert equation followed by the corresponding Fokker Plank equation. Kramer&#39;s treatment has been employed to explain the increase in coercivity in the single domain region. The single to multi-domain transformation has been assumed to explain the d

Peter Hantz, Istvan Biro

The formation of regular precipitate stripes in the wake of moving chemical reaction-diffusion fronts is investigated. Experiments on the $NaOH+CuCl_2$ reaction in PVA hydrogel yield stripes parallel or slightly oblique to the front that supplies the precursor of the precipitate. The pattern formation was modeled by phase separation described by the Cahn-Hil

D. R. Daniels, M. S. Turner

Membrane tubes (spicules) arise in cells, or artificial membranes, in the nonlinear deformation regime due to, e.g. the growth of microtubules, actin filaments or sickle hemoglobin fibers towards a membrane. We calculate the axial force exerted by the cylindrical membrane tube, and its average radius, by taking into account steric interactions between the fl

R. Combescot, X. Leyronas, M. Yu. Kagan

We investigate within a self-consistent theory the molecular instabilities arising in the normal state of a homogeneous degenerate Fermi gas, covering the whole BEC-BCS crossover. These are the standard instability for molecular formation, the BCS instability which corresponds to the formation of Cooper pairs and the related Bose-Einstein instability. These

A. Calzolari, A. Ruini, M. J. Caldas, E. Molinari

We present an ab initio study of the structural and electronic properties of styrene molecules adsorbed on the dimerized Si(100) surface at different coverages, ranging from the single-molecule to the full monolayer. The adsorption mechanism primarily involves the vinyl group via a [2+2] cycloaddition process that leads to the formation of covalent Si-C bond

Ram Seshadri

Pyrochlore dielectric materials such as (Bi$_{1.5}$Zn$_{0.5}$)(Nb$_{1.5}$Zn$_{0.5}$)O$_7$ (BZN) have generated interest because they combine high dielectric constants with small dielectric loss tangents and yet are cubic at all temperatures. The recent low-temperature preparation and structural characterization of Bi$_2$Ti$_2$O$_7$, which remains cubic down

Yshai Avishai, Daniel Berend, Luba Bromberg

We analyze the statistics of electrostatic energies (and their differences) for a quantum dot system composed of a finite number $K$ of electron islands (metallic grains) with random capacitance-inductance matrix $C$, for which the total charge is discrete, $Q=Ne$ (where $e$ is the charge of an electron and $N$ is an integer). The analysis is based on a gene

F. M. Izrailev, N. M. Makarov

We review recent results on the anomalous transport in one-dimensional and quasi-one-dimensional systems with bulk and surface disorder. Main attention is paid to the role of long-range correlations in random potentials for the bulk scattering, and in corrugated profiles for the surface scattering. It is shown that with a proper choice of correlations one ca

F. M. Izrailev, N. M. Makarov

We investigate the interplay between amplitude and square-gradient scattering from the rough surfaces in multi-mode waveguides (conducting quantum wires). The main result is that for any (even small in height) roughness the square-gradient terms in the expression for the wave scattering length (electron mean free path) are dominant, provided the correlation

Tao Zhou, Bing-Hong Wang, Pei-Ling Zhou, Chun-Xia Yang

A model of Boolean game with only one free parameter $p$ that denotes the strength of herd behavior is proposed where each agent acts according to the information obtained from his neighbors in network and those in the minority are rewarded. The simulation results indicate that the dynamic of system is sensitive to network topology, where the network of larg

Evgeny B. Stukalin, Anatoly B. Kolomeisky

Polymerization dynamics of single actin filaments is investigated theoretically using a stochastic model that takes into account the hydrolysis of ATP-actin subunits, the geometry of actin filament tips, the lateral interactions between the monomers as well as the processes at both ends of the polymer. Exact analytical expressions are obtained for a mean gro

Jian-Xin Zhu, K. McElroy, J. Lee, T. P. Devereaux

We study the $τ_1$-impurity induced $\mathbf{q}$-space pattern of the energy derivative local density of states (LDOS) in a d-wave superconductor. We are motivated in part by the recent scanning tunneling microscopy (STM) observation of strong gap inhomogeneity with weak charge density variation in Bi$_{2}$Sr$_2$CaCu$_2$O$_{8+δ}$ (BSCCO). The hypothesis is t

Yuri A. Serebrennikov

We will show that in zero magnetic field the rate of the geometric spin dephasing of a light hole in two-dimensional nanostructures is equal to the rate of the one-dimensional orientational relaxation of its crystal momentum. In contrast, this process is singularly ineffective for heavy holes.

Gregory A. Fiete, Karyn Le Hur, Leon Balents

We theoretically investigate transport in a spin incoherent one dimensional electron system, which may be realized in quantum wires at low electron density and finite temperature. Both the pure and disordered cases are considered, both in finite wires and in the thermodynamic limit. The effect of Fermi liquid leads attached to the finite length system is als

Y. N. Chen, C. M. Li, D. S. Chuu, T. Brandes

A scheme is proposed to teleport charge qubits via superradiance. Reservoir-induced entanglement is generated between two semiconductor dots in a microcavity where a quantum state encoded in a third quantum dot is then tuned into collective decay with one of the entangled dots. Teleportation is achieved automatically in our scheme which we also extend to qua

A. K. Aringazin, M. I. Mazhitov

Modeling statistical properties of motion of a Lagrangian particle advected by a high-Reynolds-number flow is of much practical interest and complement traditional studies of turbulence made in Eulerian framework. The strong and nonlocal character of Lagrangian particle coupling due to pressure effects makes the main obstacle to derive turbulence statistics

C. S. Tang, Y. H. Tan, C. S. Chu

We have investigated the time-modulated coherent quantum transport phenomena in a ballistic open quantum dot. The conductance $G$ and the electron dwell time in the dots are calculated by a time-dependent mode-matching method. Under high-frequency modulation, the traversing electrons are found to exhibit three types of resonant scatterings. They are intersid

Diego F. Torres, Olaf Reimer

A large fraction of the detections to be made by the Gamma-ray Large Area Space Telescope (GLAST) will initially be unidentified. We argue that traditional methodological approaches to identify individuals and/or populations of $γ$-ray sources will encounter procedural limitations. These limitations will hamper our ability to classify source populations lyin

D. J. Pisano, David C. Koo, Christopher N. A. Willmer, Kai Gerhard Noeske

Blue compact dwarf galaxies (BCDs) are faint (M(B) < -17 mag) compact (R <1 kpc), at least qualitatively very blue galaxies due to active star formation, and have low metallicities. Found serendipitously as part of a redshift survey of faint galaxies with the Keck Telescope (DEEP), SA 68-6597 is at a distance of 80 Mpc, and is one of the faintest, -12.4 mag,

Avanti Tilak, Christopher P. O&#39;Dea, Clive Tadhunter, Karen Willis

We present the results of HST/WFPC2 medium and narrow band imaging and VLA and MERLIN2 radio imaging of three powerful radio galaxies: 3C 171, 3C 277.3, and PKS 2250-41. We obtained images of the rest frame [OIII]$λ$5007 and [OII]$λ$3727 line emission using the Linear Ramp Filters on WFPC2. The correlations between the emission line morphology and the [OIII]

A. L. Hungerford, C. L. Fryer, G. M. Rockefeller

Multi-dimensional simulations of the neutrino-driven mechanism behind core-collapse supernovae have long shown that the explosions from this mechanism would be asymmetric. Recently, detailed core-collapse simulations have shown that the explosion may be strongest in a single direction. We present a suite of simulations modeling these ``single-lobe&#39;&#39;

Antoinette Songaila

We have analyzed the properties of metals in the high redshift intergalactic medium using a novel objective pixel optical depth technique on a sample of extremely high signal-to-noise Keck HIRES and ESI spectra of 26 quasars between redshifts 2.1 and 6.4. The technique relies on using the doublet nature of the common ions CIV and SiIV that are the principal

Lucas M. Macri

I present a review of recent observational work on Cepheid variables and eclipsing binaries in our Galaxy, the Magellanic Clouds, and other members of the Local Group.

Michael R. Meyer, Julia Greissl

We demonstrate the feasibility of detecting directly low mass stars in unresolved super-star clusters with ages < 10 Myr using near-infrared spectroscopy at modest resolution (R ~ 1000). Such measurements could constrain the ratio of high to low mass stars in these extreme star-forming events, providing a direct test on the universal nature of the initial ma

D. L. Clements, D. Farrah, M. Rowan-Robinson, J. Afonso

We present deep submillimetre photometry for 14 galaxies at z=0.5 that are hosts of type 1a supernovae, with the aim of examining the evolution of dust mass and extinction in normal galaxies. We combine these results with our previous observations of 17 z~0.5 SN1a hosts to look for any evolution in the dust content of normal galaxies between z=0 and z=0.5. T

M. Matsuura, A. A. Zijlstra, M. D. Gray, F. J. Molster

We present high-resolution images of the strongly bipolar planetary nebula NGC 6537, obtained with Hubble Space Telescope and with the infrared adaptive optics system on the Very Large Telescope. The central star is detected for the first time. Using the multi-band photometry and constraints from the dynamical age of the nebula, we derive a temperature in th

C. Guidorzi, A. Monfardini, A. Gomboc, C. G. Mundell

The 2-m robotic Liverpool Telescope reacted promptly to the gamma-ray burst GRB 050502a discovered by INTEGRAL and started observing 3 min after the onset of the GRB. The automatic identification of a bright afterglow of r&#39;~15.8 triggered for the first time an observation sequence in the BVr&#39;i&#39; filters during the first hour after a GRB. Observati

Paul Dobbie, Martin Barstow, Ivan Hubeny, Jay Holberg

We report the detection, from FUSE data, of phosphorus in the atmospheres of GD71 and two similar DA white dwarfs. This is the first detection of a trace metal in the photosphere of the spectrophotometric standard star GD71. Collectively, these objects represent the coolest DA white dwarfs in which photospheric phosphorus has been observed. We use a grid of

Enrique Vazquez-Semadeni, Jongsoo Kim, Javier Ballesteros-Paredes

We present measurements of the star formation efficiency (SFE) in 3D numerical simulations of driven turbulence in supercritical, ideal-MHD, and non-magnetic regimes, characterized by their mean normalized mass-to-flux ratio $μ$, all with 64 Jeans masses and similar rms Mach numbers ($\sim 10$). In most cases, the moderately supercritical runs with $μ= 2.8$

F. Euchner, K. Reinsch, S. Jordan, K. Beuermann

We report time-resolved optical flux and circular polarization spectroscopy of the magnetic DA white dwarf HE 1045-0908 obtained with FORS1 at the ESO VLT. Considering published results, we estimate a likely rotational period of Prot ~ 2.7 h, but cannot exclude values as high as about 9 h. Our detailed Zeeman tomographic analysis reveals a field structure wh

John Southworth, B Smalley, P F L Maxted, A Claret

WW Aurigae is a detached eclipsing binary composed of two metallic-lined A-type stars orbiting each other every 2.5 days. We have determined the masses and radii of both components to accuracies of 0.4 and 0.6 percent, respectively. From a cross-correlation analysis of high-resolution spectra we find masses of 1.964 +/- 0.007 Msun for the primary star and 1.

J D M Dewi, Ph Podsiadlowski, O R Pols

Double neutron stars (DNSs), binary systems consisting of a radio pulsar and a generally undetected second neutron star (NS), have proven to be excellent laboratories for testing the theory of general relativity. The seven systems discovered in our Galaxy exhibit a remarkably well-defined relation between the pulsar spin period and the orbital eccentricity.

C. S. Crawford, N. A. Hatch, A. C. Fabian, J. S. Sanders

We present images of NGC4696, the central galaxy in the Centaurus cluster, showing the large extent of cool filaments which are bright in H-alpha line emission. These filaments share the detailed structure of both the central dust lane and the inner regions of the arc-like plumes seen in soft X-ray emission. The X-ray gas is at its coolest, and most absorbed

B. W. Jiang, Ke Zhang, Aigen Li

The mysterious 21mu emission feature seen in 12 proto-planetary nebulae (PPNe) remains unidentified since its first detection in 1989. Over a dozen of candidate materials have been proposed within the past decade, but none of them has received general acceptance. Very recently, silicon carbide (SiC) grains with impurities were suggested to be the carrier of

Ann Merchant Boesgaard, Alex Stephens, Constantine P. Deliyannis

We have determined Li abundances in 55 metal-poor (3.6 < [Fe/H] < -0.7) stars with extreme orbital kinematics. We find the Li abundance in the Li-plateau stars and examine its decrease in low-temperature, low-mass stars. The Li observations are primarily from the Keck I telescope with HIRES (spectral resolution of ~48,000 and median signal-to-noise per pixel

H. Hernández-Saldaña, A. Robledo

We analyze the fluctuating dynamics at the golden-mean transition to chaos in the critical circle map and find that trajectories within the critical attractor consist of infinite sets of power laws mixed together. We elucidate this structure assisted by known renormalization group (RG) results. Next we proceed to weigh the new findings against Tsallis' entro

Thiago R. de Oliveira, Gustavo Rigolin, Marcos C. de Oliveira

We demonstrate that the Global Entanglement (GE) measure defined by Meyer and Wallach, J. Math. Phys. 43, 4273 (2002), is maximal at the critical point for the Ising chain in a transverse magnetic field. Our analysis is based on the equivalence of GE to the averaged linear entropy, allowing the understanding of multipartite entanglement (ME) features through

C. J. Horowitz, A. Schwenk

We present a model-independent description of low-density neutron matter based on the virial expansion. The virial equation of state provides a benchmark for all nuclear equations of state at densities and temperatures where the interparticle separation is large compared to the thermal wavelength. We calculate the second virial coefficient directly from the

Massimo Boninsegni, Nikolay Prokof&#39;ev

We establish the nature of the supersolid phase observed for hardcore bosons on the triangular lattice near half-integer filling factor, and study the phase diagram of the system at finite temperature. We find that the solid order is always of the (2m,-m&#39;,-m&#39;) with m changing discontinuously from positive to negative values at half-filling, contrary

Robert R. Caldwell, William Komp, Leonard Parker, Daniel A. T. Vanzella

We investigate the properties of a cosmological scenario which undergoes a gravitational phase transition at late times. In this scenario, the Universe evolves according to general relativity in the standard, hot Big Bang picture until a redshift z \lesssim 1. Non-perturbative phenomena associated with a minimally-coupled scalar field catalyzes a transition,

Maxim Lyutikov, Rachid Ouyed

(Abridged)Relativistic outflows carrying large scale magnetic fields have large inductive potential and may accelerate protons to ultra high energies. We discuss a novel scheme of Ultra-High Energy Cosmic Ray (UHECR) acceleration due to drifts in magnetized, cylindrically collimated, sheared jets of powerful active galaxies (with jet luminosity $\geq 10^{46}

Charles L. Epstein

In this paper we show that there is a well defined modified dbar-Neumann problem for a spin_c manifold with a strictly pseudoconvex boundary (in the contact geometry sense). We show that the index of the associated boundary value problem can be computed as the relative index between the Calderon projector on the boundary and the projector defining the bounda

Albert Schliesser, Razmick Mirzoyan

By means of third-order optical theory as well as ray-tracing simulations we have investigated the feasibility of wide-field imaging atmospheric Cherenkov telescopes with a reflective prime-focus design. For a range of desired optical resolutions, we have determined the largest available field-of-view of single-piece spherical, single-piece parabolic, tessel

A. Majumder, Xin-Nian Wang

Gluon bremsstrahlung induced by multiple parton scattering in a finite dense medium has a unique angular distribution with respect to the initial parton direction. A dead-cone structure with an opening angle $θ^2_0 \approx 2(1-z)/(zLE)$ for gluons with fractional energy $z$ arises from the Landau-Pomeranchuck-Migdal (LPM) interference. In a medium where the

Pietro Fre&#39;, Floriana Gargiulo, Ksenya Rulik, Mario Trigiante

In this paper we study the systematics of the affine extension of supergravity duality algebras when we step down from D=4 to D=2. For all D=4 supergravities (with N >= 3) there is a universal field theoretical mechanism promoting the extension, which relies on the coexistence of two non locally related lagrangian descriptions. This provides a Chevalley-Serr