March 2006 arXiv papers — page 28

Sean P. Meyn

Consider the normalized partial sums of a real-valued function $F$ of a Markov chain, \[ϕ_n:=n^{-1}\sum_{k=0}^{n-1}F(Φ(k)),\qquad n\ge1.\] The chain $\{Φ(k):k\ge0\}$ takes values in a general state space $\mathsf {X}$, with transition kernel $P$, and it is assumed that the Lyapunov drift condition holds: $PV\le V-W+b\mathbb{I}_C$ where $V:\mathsf {X}\to(0,\i

D. R. McDonald, J. Reynier

RED (Random Early Detection) has been suggested when multiple TCP sessions are multiplexed through a bottleneck buffer. The idea is to detect congestion before the buffer overflows by dropping or marking packets with a probability that increases with the queue length. The objectives are reduced packet loss, higher throughput, reduced delay and reduced delay

Cedric Boutillier

In this paper, we introduce a family of observables for the dimer model on a bi-periodic bipartite planar graph, called pattern density fields. We study the scaling limit of these objects for liquid and gaseous Gibbs measures of the dimer model, and prove that they converge to a linear combination of a derivative of the Gaussian massless free field and an in

Martin Dyer, Leslie Ann Goldberg, Mark Jerrum

We address the problem of sampling colorings of a graph $G$ by Markov chain simulation. For most of the article we restrict attention to proper $q$-colorings of a path on $n$ vertices (in statistical physics terms, the one-dimensional $q$-state Potts model at zero temperature), though in later sections we widen our scope to general ``$H$-colorings''

C. Bouzar, R. Chaili

We give a microlocal version of the theorem of iterates in multi-anisotropic Gevrey classes for multi-anisotropic hypoelliptic differential operators

Toshiyuki Kobayashi

This article gives an up-to-date account of the theory of discrete group actions on non-Riemannian homogeneous spaces. As an introduction of the motifs of this article, we begin by reviewing the current knowledge of possible global forms of pseudo-Riemannian manifolds with constant curvatures, and discuss what kind of problems we propose to pursue. For pseud

Toshiyuki Kobayashi, Salma Nasrin

We consider the deformation of a discontinuous group acting on the Euclidean space by affine transformations. A distinguished feature here is that even a `small' deformation of a discrete subgroup may destroy proper discontinuity of its action. In order to understand the local structure of the deformation space of discontinuous groups, we introduce the c

Jaime A. Londoño

We propose a new approach to utilities that is consistent with state-dependent utilities. In our model utilities reflect the level of consumption satisfaction of flows of cash in future times as they are valued when the economic agents are making their consumption and investment decisions. The theoretical framework used for the model is one proposed by the a

Denis G. Gaidashev

The boundary of the Siegel disk of a quadratic polynomial with an irrationally indifferent fixed point with the golden mean rotation number has been observed to be self-similar. The geometry of this self-similarity is universal for a large class of holomorphic maps. A renormalization explanation of this universality has been proposed in the literature. Howev

Bruno Lombard, Joël Piraux

The propagation of elastic waves in a fractured rock is investigated, both theoretically and numerically. Outside the fractures, the propagation of compressional waves is described in the simple framework of one-dimensional linear elastodynamics. The focus here is on the interactions between the waves and fractures: for this purpose, the mechanical behavior

Johan Jonasson

The overhand shuffle is one of the ``real'' card shuffling methods in the sense that some people actually use it to mix a deck of cards. A mathematical model was constructed and analyzed by Pemantle [J. Theoret. Probab. 2 (1989) 37--49] who showed that the mixing time with respect to variation distance is at least of order $n^2$ and at most of order

Bertrand Toen, Gabriele Vezzosi

This is the second part of a series of papers devoted to develop Homotopical Algebraic Geometry. We start by defining and studying generalizations of standard notions of linear and commutative algebra in an abstract monoidal model category, such as derivations, etale and smooth maps, flat and projective modules, etc. We then use the theory of stacks over mod

V. Elias, T. G. Steele

We consider in detail the analytic behaviour of the non-interacting massless scalar field two-point function in H.S. Snyder's discretized non-commuting spacetime. The propagator we find is purely real on the Euclidean side of the complex $p^2$ plane and goes like $1/p^2$ as $p^2\to 0$ from either the Euclidean or Minkowski side. The real part of the prop

Benjamin A. Burrington, James T. Liu, Leopoldo A. Pando Zayas

Many conformal quiver gauge theories admit nonconformal generalizations. These generalizations change the rank of some of the gauge groups in a consistent way, inducing a running in the gauge couplings. We find a group of discrete transformation that acts on a large class of these theories. These transformations form a central extension of the Heisenberg gro

G. Arutyunov, A. A. Tseytlin

We consider the highest-energy state in the su(1|1) sector of N=4 super Yang-Mills theory containing operators of the form tr(Z^{L-M} ψ^M) where Z is a complex scalar and ψis a component of gaugino. We show that this state corresponds to the operator tr(ψ^L) and can be viewed as an analogue of the antiferromagnetic state in the su(2) sector. We find perturba

Matthias Blau, Denis Frank, Sebastian Weiss

We propose a formulation of the Penrose plane wave limit in terms of null Fermi coordinates. This provides a physically intuitive (Fermi coordinates are direct measures of geodesic distance in space-time) and manifestly covariant description of the expansion around the plane wave metric in terms of components of the curvature tensor of the original metric, a

Inaki Garcia-Etxebarria, Fouad Saad, Angel M. Uranga

The gauge theory on a set of D3-branes at a toric Calabi-Yau singularity can be encoded in a tiling of the 2-torus denoted dimer diagram (or brane tiling). We use these techniques to describe the effect on the gauge theory of geometric operations partially smoothing the singularity at which D3-branes sit, namely partial resolutions and complex deformations.

A. Aguirre, T. Banks, M. Johnson

In a previous paper, two of the authors presented a "regulated" picture of eternal inflation. This picture both suggested and drew support from a conjectured discontinuity in the amplitude for tunneling from positive to negative vacuum energy, as the positive vacuum energy was sent to zero; analytic and numerical arguments supporting this conjecture

Nikos Irges, Mirian Tsulaia

We develop a method for relating the boundary effective action associated with an orbifold of the D+1 dimensional theory of a p-form field to D dimensional fluxed Chern-Simons type of terms. We apply the construction to derive from twelve dimensions the Chern-Simons terms of the eleven dimensional supergravity theory in the presence of flux.

Kazuya Koyama, Federico Piazza, David Wands

We investigate whether enhanced gravitational scattering on small scales (< 0.1mm), which becomes possible in models with large extra dimensions, can establish statistical equilibrium between different particle species in the early Universe. We calculate the classical relativistic energy transfer rate for two species with a large ratio between their masses f

T. J. Battefeld, S. P. Patil, R. H. Brandenberger

In this report, we study within the context of general relativity with one extra dimension compactified either on a circle or an orbifold, how radion fluctuations interact with metric fluctuations in the three non-compact directions. The background is non-singular and can either describe an extra dimension on its way to stabilization, or immediately before a

Vladimir A. Petrov

On the basis of the RG invariance we show, in particular, that the Regge trajectory intercept cannot be calculated as a function of the coupling constant.

Ezequiel Alvarez

In this work we study the T, CP and CPT symmetries in the B-meson system. Our analysis and results are addressed to the case of correlated mesons in the B-factories. In the first set of theory and results we investigate the consequences of these discrete symmetries in the B-mixing and interference between mixing and decay. With the help of the CP-tag we comp

Hirotsugu Fujii, Francois Gelis, Raju Venugopalan

A consistent treatment of both multiple scattering and small x quantum evolution effects on pair production in high energy pA collisions is feasible in the framework of the Color Glass Condensate (hep-ph/0402257). We first discuss the properties of quark pair production in the classical effective theory where only multiple scattering effects are included. Ex

Darwin Chang, Hoang Ngoc Long

We investigate a simple model of neutrino mass based on SU(3)_C X SU(3)_L X U(1)_X gauge unification. The Yukawa coupling of the model has automatic lepton-number symmetry which is broken only by the self-couplings of the Higgs boson. At tree level, neutrino spectrum contains three Dirac fermions, one massless and two degenerate in mass. At the two loop-leve

Wei-Shu Hou, Makiko Nagashima, Guy Raz, Andrea Soddu

The fourth generation can give the correct trend of S_{phi K^0}, S_{pi^0 K^0} < sin2phi_1/beta, as indicated by data, and the effect, being largely leading order, is robust against hadronic uncertainties. The effect on S_{eta&#39; K^0}, however, is diluted away by hadronic effects, and S_{eta&#39; K^0} \simeq sin2phi_1/beta is expected. The near maximal arg[

Yousuke Nakamura, Yoshinobu Kuramashi

We calculate one-loop renormalization factors of generic DeltaS=2 four-quark operators for domain-wall QCD with the plaquette gauge action and the Iwasaki gauge action. The renormalization factors are presented in the modified minimal subtraction (MS-bar) scheme with the naive dimensional regularization. As an important application we show how to construct t

Christian Koenigsdoerffer, Achamveedu Gopakumar

We obtain an efficient description for the dynamics of nonspinning compact binaries moving in inspiralling eccentric orbits to implement the phasing of gravitational waves from such binaries at the 3.5 post-Newtonian (PN) order. Our computation heavily depends on the phasing formalism, presented in [T. Damour, A. Gopakumar, and B. R. Iyer, Phys. Rev. D \text

Vladimir S. Mashkevich

The treatment of the principle of general covariance based on coordinate systems, i.e., on classical tensor analysis suffers from an ambiguity. A more preferable formulation of the principle is based on modern differential geometry: the formulation is coordinate-free. Then the principle may be called ``principle of geometricity.&#39;&#39; In relation to coor

David Eppstein, Michael T. Goodrich, Nodari Sitchinava

Motivated by secure wireless networking, we consider the problem of placing fixed localizers that enable mobile communication devices to prove they belong to a secure region that is defined by the interior of a polygon. Each localizer views an infinite wedge of the plane, and a device can prove membership in the secure region if it is inside the wedges for a

Ashfaq N Shaik

This paper presents watermarking algorithms using d-sequences so that the peak signal to noise ratio (PSNR) is maximized and the distortion introduced in the image due to the embedding is minimized. By exploiting the cross correlation property of decimal sequences, the concept of embedding more than one watermark in the same cover image is investigated.

Martin Grohe, Oleg Verbitsky

Our starting point is the observation that if graphs in a class C have low descriptive complexity in first order logic, then the isomorphism problem for C is solvable by a fast parallel algorithm (essentially, by a simple combinatorial algorithm known as the multidimensional Weisfeiler-Lehman algorithm). Using this approach, we prove that isomorphism of grap

A. Ai T -Bouziad, Irene Guessarian, L. Vieille

Given a constraint $c$ assumed to hold on a database $B$ and an update $u$ to be performed on $B$, we address the following question: will $c$ still hold after $u$ is performed? When $B$ is a relational database, we define a confluent terminating rewriting system which, starting from $c$ and $u$, automatically derives a simplified weakest precondition $wp(c,

Francesco Ranzato, Francesco Tapparo

Standard abstract model checking relies on abstract Kripke structures which approximate concrete models by gluing together indistinguishable states, namely by a partition of the concrete state space. Strong preservation for a specification language L encodes the equivalence of concrete and abstract model checking of formulas in L. We show how abstract interp

Denis D. Sheka

Very recently Fonseca and Pires [Phys. Rev. B 73, 012403(2006)] have studied the soliton--magnon scattering for the isotropic antiferromagnet and calculated ``exact&#39;&#39; phase shifts, which were compared with the ones obtained by the Born approximation. In this Comment we correct both the soliton and magnon solutions and point out the way how to study c

Y. Jung, S. Torquato

It has recently been shown that triply periodic two-phase bicontinuous composites with interfaces that are the Schwartz primitive (P) and diamond (D) minimal surfaces are not only geometrically extremal but extremal for simultaneous transport of heat and electricity. The multifunctionality of such two-phase systems has been further established by demonstrati

Diego Kienle, Jorge I. Cerda, Kirk H. Bevan, Gengchiau Liang

In this second paper, we develop transferable semi-empirical parameters for the technologically important material, silicon, using Extended Huckel Theory (EHT) to calculate its electronic structure. The EHT-parameters areoptimized to experimental target values of the band dispersion of bulk-silicon. We obtain a very good quantitative match to the bandstructu

M. Le Tacon, A. Sacuto, A. Georges, G. Kotliar

The superconducting state of underdoped cuprates is often described in terms of a single energy-scale, associated with the maximum of the (d-wave) gap. Here, we report on electronic Raman scattering results, which show that the gap function in the underdoped regime is characterized by two energy scales, depending on doping in opposite manners. Their ratios t

Ron Bourgoin

Several surprises are beginning to emerge from studies of nanostructures: whereas increased resistance with decreased thickness has been expected, the exact opposite in several instances has been found. It is beginning to seem we are in the process of wedging open the way to a superconductor that will operate at least at room temperature. This paper will exa

M. A. Hoefer, M. J. Ablowitz, I. Coddington, E. A. Cornell

A Bose-Einstein condensate (BEC) is a quantum fluid that gives rise to interesting shock wave nonlinear dynamics. Experiments depict a BEC that exhibits behavior similar to that of a shock wave in a compressible gas, eg. traveling fronts with steep gradients. However, the governing Gross-Pitaevskii (GP) equation that describes the mean field of a BEC admits

E. Castro-Camus, J. Lloyd-Hughes, M. D. Fraser, H. H. Tan

We have developed a detector which records the full polarisation state of a terahertz (THz) pulse propagating in free space. The three-electrode photoconductive receiver simultaneously records the electric field of an electromagnetic pulse in two orthogonal directions as a function of time. A prototype device fabricated on Fe+ ion implanted InP exhibited a c

M. A. Bab, G. Fabricius, E. V. Albano

The short-time dynamic evolution of an Ising model embedded in an infinitely ramified fractal structure with noninteger Hausdorff dimension was studied using Monte Carlo simulations. Completely ordered and disordered spin configurations were used as initial states for the dynamic simulations. In both cases, the evolution of the physical observables follows a

M. A. Bab, G. Fabricius, E. V. Albano

The nonequilibrium critical dynamics of the Ising magnet on a fractal substrate, namely the Sierpinski carpet with Hausdorff dimension $d_H$ =1.7925, has been studied within the short-time regime by means of Monte Carlo simulations. The evolution of the physical observables was followed at criticality, after both annealing ordered spin configurations (ground

P. Pierobon, T. Franosch, E. Frey

We investigate the non-equilibrium steady state of a one-dimensional (1D) lattice gas of dimers. The dynamics is described by a totally asymmetric exclusion process (TASEP) supplemented by attachment and detachment processes, mimicking chemical equilibrium of the 1D driven transport with the bulk reservoir. The steady-state phase diagram, current and density

Pierre Gaspard

An overview is given of recent advances in nonequilibrium statistical mechanics on the basis of the theory of Hamiltonian dynamical systems and in the perspective provided by the nanosciences. It is shown how the properties of relaxation toward a state of equilibrium can be derived from Liouville&#39;s equation for Hamiltonian dynamical systems. The relaxati

P. Dalmas de Reotier, A. Yaouanc, L. Keller, A. Cervellino

We report a study of the geometrically frustrated magnetic material Tb2Sn2O7 by the positive muon spin relaxation technique. No signature of a static magnetically ordered state is detected while neutron magnetic reflections are observed in agreement with a published report. This is explained by the dynamical nature of the ground state of Tb2Sn2O7: the Tb3+ m

A. D. Mirlin, Y. V. Fyodorov, A. Mildenberger, F. Evers

Two exact relations between mutlifractal exponents are shown to hold at the critical point of the Anderson localization transition. The first relation implies a symmetry of the multifractal spectrum linking the multifractal exponents with indices $q<1/2$ to those with $q>1/2$. The second relation connects the wave function multifractality to that of Wigner d

Lucia Canova, Michal Jascur

The generalized Fisher super-exchange antiferromagnetic model with uniaxial crystal-field anisotropy is exactly investigated using an extended mapping technique. An exact relation between partition function of the studied system and that one of the standard zero-field spin-1/2 Ising model on the corresponding lattice is obtained applying the decoration-itera

C. A. Kuntscher, S. Frank, A. Pashkin, M. Hoinkis

We studied the transmittance and reflectance of the low-dimensional Mott-Hubbard insulator TiOCl in the infrared and visible frequency range as a function of pressure. The strong suppression of the transmittance and the abrupt increase of the near-infrared reflectance above 12 GPa suggest a pressure-induced insulator-to-metal transition. The pressure-depende

Cyril Dubus, Jean-Baptiste Fournier

We study a Gaussian model of the membrane of red blood cells: a &#34;phantom&#34; triangular network of springs attached at its vertices to a fluid bilayer with curvature elasticity and tension. We calculate its fluctuation spectrum and we discuss the different regimes and non-monotonic features, including the precise crossover at the mesh size between the a

Manuel I. Marques, Carmen Arago

The frequency dependence of the dielectric permitivity&#39;s maximum has been studied for poled and unpoled doped relaxor strontium barium niobate $Sr_{0.61}Ba_{0.39}Nb_{2}O_{6}:Cr^{3+}$ (SBN-61:Cr). In both cases the maximum found is broad and the frequency dispersion is strong. The present view of random fields compensation in the unpoled sample is not sui

D. A. Rowlands

Recently the nonlocal coherent-potential approximation (NLCPA) has been introduced by Jarrell and Krishnamurthy for describing the electronic structure of substitutionally disordered systems. The NLCPA provides systematic corrections to the widely used coherent-potential approximation (CPA) whilst preserving the full symmetry of the underlying lattice. Here

M. Evangelisti, F. Luis, L. J. de Jongh, M. Affronte

We critically review recent results obtained by studying the low-temperature specific heat of some of the most popular molecular magnets. Perspectives of this field are discussed as well.

M. R. Graeber, W. A. Coish, C. Hoffmann, M. Weiss

We report electrical transport measurements through a semiconducting single-walled carbon nanotube (SWNT) with three additional top-gates. At low temperatures the system acts as a double quantum dot with large inter-dot tunnel coupling allowing for the observation of tunnel-coupled molecular states extending over the whole double-dot system. We precisely ext

N. Seferoglu, B. Kutlu

The spin-1 Ising (BEG) model with the nearest-neighbour bilinear and biquadratic interactions and single-ion anisotropy is simulated on a cellular automaton which improved from the Creutz cellular automaton(CCA) for a simple cubic lattice. The simulations have been made for several sets of parameters $K/J$ and $D/J$ in the $-3<D/J\leq 0$ and $-1\leq K/J\leq

Navin Singh, Yashwant Singh

We considered a dsDNA polymer in which distribution of bases are random at the base pair level but ordered at a length of 18 base pairs and calculated its force elongation behaviour in the constant extension ensemble. The unzipping force $F(y)$ vs. extension $y$ is found to have a series of maxima and minima. By changing base pairs at selected places in the

V. Ya. Demikhovskii, D. V. Khomitsky

The Bloch spinors, energy spectrum and spin density in energy bands are studied for the two-dimensional electron gas (2DEG) with Rashba spin-orbit (SO) interaction subject to one-dimensional (1D) periodic electrostatic potential of a lateral superlattice. The space symmetry of the Bloch spinors with spin parity is studied. It is shown that the Bloch spinors

Dario Poletti, Libin Fu, Jie Liu, Baowen Li

We investigate the quantum dynamics of a periodically kicked Bose-Einstein Condensate confined in a one dimensional (1D) Box both numerically and theoretically, emphasizing on the phenomena of quantum resonance and anti-resonance. The quantum resonant behavior of BEC is different from the single particle case but the anti-resonance condition ($T = 2π$ and $α

Suman Chakrabarty, Dwaipayan Chakrabarti, Biman Bagchi

Orientational dynamics in a liquid crystalline system near the isotropic-nematic (I-N) phase transition is studied using Molecular Dynamics simulations of the well-known Lebwohl-Lasher (LL) model. As the I-N transition temperature is approached from the isotropic side, we find that the decay of the orientational time correlation functions (OTCF) slows down n

Hidetsugu Sakaguchi

We study the Schloegl model in a vesicle with semi-permeable membrane. The diffusion constant takes a smaller value in the membrane region, which prevents the outflow of self-catalytic product. A nonequilibrium state is stably maintained inside of the vesicle. Nutrients are absorbed and waste materials are exhausted through the membrane by diffusion. It is i

Paolo Politi

We face the problem to determine the slope dependent current during the epitaxial growth process of a crystal surface. This current is proportional to delta=(p+) + (p-), where (p+/-) are the probabilities for an atom landing on a terrace to attach to the ascending (p+) or descending (p-) step. If the landing probability is spatially uniform, the current is p

L. Sanchez-Palencia, V. Ahufinger, A. Kantian, Jakub Zakrzewski

We investigate theoretically the low-temperature physics of a two-component ultracold mixture of bosons and fermions in disordered optical lattices. We focus on the strongly correlated regime. We show that, under specific conditions, composite fermions, made of one fermion plus one bosonic hole, form. The composite picture is used to derive an effective Hami

David Charbonneau, Timothy M. Brown, Adam Burrows, Greg Laughlin

When extrasolar planets are observed to transit their parent stars, we are granted unprecedented access to their physical properties. It is only for transiting planets that we are permitted direct estimates of the planetary masses and radii, which provide the fundamental constraints on models of their physical structure. In particular, precise determination

G. Beskin, A. Biryukov, S. Karpov

The recent massive measurements of pulsar frequency second derivatives have shown that they are 100-1000 times larger than expected for standard pulsar slowdown low. Moreover, the second derivatives as well as braking indices are even negative for about half of pulsars. We explain these paradoxical results on the basis of the statistical analysis of the rota

Stefano Profumo, Kris Sigurdson, Marc Kamionkowski

We calculate the kinetic-decoupling temperature for weakly interacting massive particles (WIMPs) in supersymmetric (SUSY) and universal-extra-dimension (UED) models that can account for the cold-dark-matter abundance determined from cosmic microwave background measurements. Depending on the parameters of the particle-physics model, a wide variety of decoupli

Chris Quigg

I review the essentials of ultrahigh-energy neutrino interactions, show how neutral-current detection and flavor tagging can enhance the scientific potential of neutrino telescopes, and sketch new studies on neutrino encounters with dark matter relics and on gravitational lensing of neutrinos.

R. A. Fesen, M. C. Hammell, J. Morse, R. A. Chevalier

HST ACS images of the young SN remnant Cas A are used to explore the expansion and spatial distribution of its highest velocity debris. Proper motions of over 1800 outlying ejecta knots are reported. The distribution of transverse expansion velocities for these knots shows a striking bipolar asymmetry with the highest velocity knots confined to nearly opposi

D. L. Padgett, L. Cieza, K. R. Stapelfeldt, N. J. Evans

Using the Spitzer Space Telescope, we have observed 90 weak-line and classical T Tauri stars in the vicinity of the Ophiuchus, Lupus, Chamaeleon, and Taurus star-forming regions as part of the Cores to Disks (c2d) Spitzer Legacy project. In addition to the Spitzer data, we have obtained contemporaneous optical photometry to assist in constructing spectral en

Alexey Boyarsky, Andrey Neronov, Oleg Ruchayskiy, Mikhail Shaposhnikov

We find restrictions on the mass and mixing angle of the dark matter sterile neutrinos using X-ray observations of Coma and Virgo galaxy clusters.

Y. Wiaux, P. Vielva, E. Martinez-Gonzalez, P. Vandergheynst

We question the global universe isotropy by probing the alignment of local structures in the cosmic microwave background (CMB) radiation. The original method proposed relies on a steerable wavelet decomposition of the CMB signal on the sphere. The analysis of the first-year WMAP data identifies a mean preferred plane with a normal direction close to the CMB

Ian Stewart

A procedure is described for estimating an optimum kernel for the detection by convolution of signals among Poissonian noise. The technique is applied to the detection of x-ray point sources in XMM-Newton data, and is shown to yield an improvement in detection sensitivity of up to 60% over the sliding-box method used in the creation of the 1XMM catalog.

Jacek Niemiec, Michal Ostrowski, Martin Pohl

The present paper is the last of a series studying the first-order Fermi acceleration processes at relativistic shock waves with the method of Monte Carlo simulations applied to shocks propagating in realistically modeled turbulent magnetic fields. The model of the background magnetic field structure of Niemiec & Ostrowski (2004, 2006) has been augmented her

K. Katarzynski, G. Ghisellini, A. Mastichiadis, F. Tavecchio

We analyse the influence of the stochastic particle acceleration for the evolution of the electron spectrum. We assume that all investigated spectra are generated inside a spherical, homogeneous source and also analyse the synchrotron and inverse Compton emission generated by such an object. The stochastic acceleration is treated as the diffusion of the part

Abraham Loeb

The first dwarf galaxies, which constitute the building blocks of the collapsed objects we find today in the Universe, had formed hundreds of millions of years after the big bang. This pedagogical review describes the early growth of their small-amplitude seed fluctuations from the epoch of inflation through dark matter decoupling and matter-radiation equali

E. Hatziminaoglou, J. Fritz, I. Perez-Fournon, A. Franceschini

This work focuses on the properties of dusty tori in active galactic nuclei (AGN) derived from the comparison of SDSS type 1 quasars with mid-Infrared (MIR) counterparts and a new, detailed torus model. The infrared data were taken by the Spitzer Wide-area InfraRed Extragalactic (SWIRE) Survey. Basic model parameters are constraint, such as the density law o

E. A. Bergin, Y. Aikawa, G. A. Blake, E. F. van Dishoeck

In this review we re-evaluate our observational and theoretical understanding of the chemical evolution of protoplanetary disks. We discuss how improved observational capabilities have enabled the detection of numerous molecules exposing an active disk chemistry that appears to be in disequilibrium. We outline the primary facets of static and dynamical theor

J. Ballesteros-Paredes, R. S. Klessen, M. -M. Mac Low, E. Vazquez-Semadeni

We review the properties of turbulent molecular clouds (MCs), focusing on the physical processes that influence star formation (SF). MC formation appears to occur during large-scale compression of the diffuse ISM driven by supernovae, magnetorotational instability, or gravitational instability in galactic disks of stars and gas. The compressions generate tur

R. K. Saito, R. Baptista

We report a study of the spectra and structure of the accretion disk of the dwarf nova V2051 Ophiuchi while the star was in an unusual faint brightness state during 1996. The differences between the UV resonant lines and continuum disk surface brightness distributions indicate a vertically extended disk with the emission from these lines arising from the upp

Paul Goudfrooij, Diane Gilmore, Markus Kissler-Patig, Claudia Maraston

We present accurate integrated-light photometry in Johnson/Cousins V, R, and I for a sample of 28 globular clusters in the Magellanic Clouds. The majority of the clusters in our sample have reliable age and metallicity estimates available in the literature. The sample encompasses ages between 50 Myr and 7 Gyr, and metallicities ([Fe/H]) between -1.5 and 0.0

Andrew Cumming

The last few years have seen the discovery of a number of new aspects of Type I X-ray bursts: the extremely energetic and long duration superbursts, intermediate duration bursts at low luminosities, mHz QPOs, and burst oscillations. These discoveries promise a new understanding of nuclear burning on accreting neutron stars, and offer a chance to use observat

P. Salome, F. Combes, A. C. Edge, C. Crawford

Cold molecular gas has been recently detected in several cooling flow clusters of galaxies where huge optical nebulosities often stand. These optical filaments are tightly linked to the cooling flow and to the related phenomena, like the rising bubbles of relativistic plasma, fed by the radio jets. We present here a map in the CO(2-1) rotational line of the

L. P. Bassino, F. R. Faifer, J. C. Forte, B. Dirsch

We present a Washington C and Kron-Cousins R photometric study of the globular cluster system of NGC 1399, the central galaxy of the Fornax cluster. A large areal coverage of 1 square degree around NGC 1399 is achieved with three adjoining fields of the MOSAIC II Imager at the CTIO 4-m telescope. Working on such a large field, we can perform the first indica

A. Kandus, M. J. Vasconcelos, A. H. Cerqueira

We study in the present paper how Hall effect modifies the quenching process of the electromotive force (e.m.f.) in Mean Field Dynamo (MFD) theories. We write down the evolution equations for the e.m.f. and for the large and small scale magnetic helicity, treat Hall effect as a perturbation and integrate the resulting equations assuming boundary conditions s

D. de Martino, G. Matt, K. Mukai, J. -M. Bonnet-Bidaud

XMM-Newton observations aimed at determining for the first time the broad-band X-ray properties of the faint high galactic latitude Intermediate Polar UU Col are presented. We performed X-ray timing analysis in different energy ranges of the EPIC cameras which reveals the dominance of the 863s white dwarf rotational period. The spin pulse is strongly energy

Seitaro Urakawa, Toru Yamada, Yasushi Suto, Edwin. L. Turner

We report the results of a prototype photometric search for transiting extrasolar planets using Subaru Suprime-Cam. Out of about 100,000 stars monitored around the Galactic plane (l=90 degree,b=0 degree), we find that 7,700 (27,000) stars show the photometric precision below 1% (3%) for 60 second exposures which is required to detect extrasolar planets by th

Alessandro Capetti, Barbara Balmaverde

[ABRIDGED] This is the third in a series of three papers exploring the connection between the multiwavelength properties of AGN in nearby early-type galaxies and the characteristics of their hosts. We selected 116 AGN candidates requiring a radio flux of 1 mJy. We classified the objects with HST images into ``core&#39;&#39; and ``power-law&#39;&#39; galaxies

Motohide Tamura, Misato Fukagawa, Hiroshi Kimura, Tetsuo Yamamoto

High-resolution K band imaging polarimetry of the beta Pic dust disk has been conducted with adaptive optics and a coronagraph using the Subaru 8.2-m telescope. Polarization of ~10 % is detected out to r ~ 120 AU with a centro-symmetric vector pattern around the central star, confirming that the disk is seen as an infrared reflection nebula. We have modeled

Johan Hansson

We make the case for the existence of a, hitherto unknown and unobserved, hierarchy of ever more compact cosmic objects in the universe. This hypothesis is based on i) the assumption of &#34;elementary&#34; particle sub-constituents on several levels below the presently known, inspired by Glashow&#39;s &#34;blooming desert&#34;, ii) the existence of nearly s

CH. Helling, W. -F. Thi, P. Woitke, M. Fridlund

Dust clouds influence the atmospheric structure of brown dwarfs, and they affect the heat transfer and change the gas-phase chemistry. However, the physics of their formation and evolution is not well understood. In this letter, we predict dust signatures and propose a potential observational test of the physics of dust formation in brown dwarf atmosphere ba

E. W. Schmidt, S. Schippers, A. Mueller, M. Lestinsky

Recent spectroscopic models of active galactic nuclei (AGN) have indicated that the recommended electron-ion recombination rate coefficients for iron ions with partially filled M-shells are incorrect in the temperature range where these ions form in photoionized plasmas. We have investigated this experimentally for Fe XIV forming Fe XIII. The recombination r

P. Jiang, J. X. Wang, T. G. Wang

Most Active Galactic Nuclei (AGN) exhibit a narrow Fe Kalpha line at ~ 6.4 keV in the X-ray spectra, due to the fluorescent emission from cold material far from the inner accretion disk. Using XMM-Newton observations, Page et al. found that the equivalent width (EW) of the narrow Fe Kalpha line decreases with increasing luminosity (EW ~ L^-0.17pm0.08), sugge

Tsutomu T. Takeuchi

Dust plays crucial roles in galaxy formation and evolution. In the early epoch of galaxy evolution dust is only supplied by supernovae (SNe). With the aid of a new physical model of dust production by SNe, we constructed a model of dust emission from forming galaxies. We show the evolution of the spectral energy distribution (SED). Then we adopt this model t

Stuart D. Ryder, Clair E. Murrowood, Raylee A. Stathakis

We present images taken with the GMOS instrument on Gemini-South, in excellent (<0.5 arcsec) seeing, of SN 2001ig in NGC 7424, ~1000 days after explosion. A point source seen at the site of the SN is shown to have colours inconsistent with being an H II region or a SN 1993J-like remnant, but can be matched to a late-B through late-F supergiant with A_V<1. We

Hugh R. A. Jones, R. Paul Butler, C. G. Tinney, Geoffrey W. Marcy

We report Doppler measurements of the stars HD187085 and HD20782 which indicate two high eccentricity low-mass companions to the stars. We find HD187085 has a Jupiter-mass companion with a ~1000d orbit. Our formal `best fit&#39; solution suggests an eccentricity of 0.47, however, it does not sample the periastron passage of the companion and we find that orb

Stuart Wyithe, T. Padmanabhan

In the local universe, the masses of Super-Massive Black-Holes (SMBH) appear to correlate with the physical properties of their hosts, including the mass of the dark-matter halo. Using these clues as a starting point many studies have produced models that can explain phenomena like the quasar luminosity function. The shortcoming of this approach is that work

D. E. Welty, S. R. Federman, R. Gredel, J. A. Thorburn

We discuss the abundances of interstellar CH, CH+, and CN in the Magellanic Clouds (MC), derived from spectra of 7 SMC and 13 LMC stars obtained (mostly) with the VLT/UVES. CH and/or CH+ are detected toward 3 SMC and 9 LMC stars; CN is detected toward 2 stars. In the MC, the CH/H2 ratio is comparable to that found for diffuse Galactic molecular clouds in som

T. J. Davidge

The stellar content of the spiral galaxy NGC 247 is investigated. The main sequence turn-off (MSTO) in the inner 12 kpc of the disk corresponds to an age of 6 Myr. A mean star formation rate (SFR) of 0.1 solar masses per year during the past 16 Myr is computed from star counts. The color of the red supergiant plume does not change with radius, suggesting tha

Noelia E. D. Noel, Carme Gallart, Edgardo Costa, Rene A. Mendez

We present ground-based {\it B} and {\it R}-band color-magnitude diagrams (CMDs) of unprecedented depth for twelve fields in the Small Magellanic Cloud (SMC). They reach the oldest main-sequence turnoffs and cover a wide range of galactocentric distances up to $\sim4\arcdeg$ from the SMC center, and are located at different position angles. A picture of the

Igor Bulyzhenkov

The intrinsic metric symmetries for energy-momentum in warped space-time universally reinforce strict spatial flatness in the GR metric formalism. The passive/active energy-charge for the 1686, 1913, and 1915 gravitational laws maintains the universal free fall in non-empty material space of nonlocal elementary (radial) energies. The known planetary periheli

K. Henderson, H. Kelkar, T. C. Li, B. Gutierrez-Medina

We study the effect of different heating rates of a dilute Bose gas confined in a quasi-1D finite, leaky box. An optical kicked-rotor is used to transfer energy to the atoms while two repulsive optical beams are used to confine the atoms. The average energy of the atoms is localized after a large number of kicks and the system reaches a nonequilibrium steady