March 2006 arXiv papers — page 40

Dietrich Stauffer, Xavier Castello, Victor M. Eguiluz, Maxi San Miguel

The differential equations of Abrams and Strogatz for the competition between two languages are compared with agent-based Monte Carlo simulations for fully connected networks as well as for lattices in one, two and three dimensions, with up to 10^9 agents.

Maria del Pilar Monsivais-Alonso

One of the most active areas of physics in the last decades has been that of critical phenomena, and Monte Carlo simulations have played an important role as a guide for the validation and prediction of system properties close to the critical points. The kind of phase transitions occurring for the Betts lattice (lattice constructed removing 1/7 of the sites

S. Pustelny, D. F. Kimball, S. M. Rochester, V. V. Yashchuk

Specific types of atomic coherences between Zeeman sublevels can be generated and detected using a method based on nonlinear magneto-optical rotation with frequency modulated light. Linearly polarized, frequency modulated light is employed to selectively generate ground-state coherences between Zeeman sublevels for which $Δm=2$ and $Δm=4$ in $^{85}$Rb and $^

V. Shaidurov

When analyzing the mean-year trend of the Earth's surface temperature for the past 140 years one can discern two sections of monotone linear increase of temperature during two last industrial centuries. The first one begins somewhere in the period 1906-1909. The previous segment demonstrates a weak decrease in the temperature trend, not increase. For exp

G. Hagen, J. S. Vaagen

Solution of the momentum space Schrödinger equation in the case of deformed fields is being addressed. In particular it is shown that a complete set of single particle states which includes bound, resonant and complex continuum states may be obtained by the Contour Deformation Method. This generalized basis in the complex energy plane is known as a Berggren

F. M. Steffens, W. Melnitchouk

We propose a new implementation of target mass corrections to nucleon structure functions which, unlike existing treatments, has the correct kinematic threshold behavior at finite Q^2 in the x -> 1 limit. We illustrate the differences between the new approach and existing prescriptions by considering specific examples for the F_2 and F_L structure functions,

Lothar Tiator, Sabit Kamalov

MAID is a unitary isobar model for a partial wave analysis of pion photo- and electroproduction in the resonance region. It is fitted to the world data and can give predictions for multipoles, amplitudes, cross sections and polarization observables in the energy range from pion threshold up to W=2 GeV and photon virtualities Q^2 < 5 GeV^2. Using more recent

J. H. O. Sales, T. Frederico, B. M. Pimentel, B. V. Carlson

We developed the formal connection of the field theoretical Bethe-Salpeter equation including the ladder approximation with its representation on the light-front for a bosonic model. We use the light-front Green&#39;s function for the N-particle system for two-particles plus N-2 intermediate bosons. We derived an infinite set of coupled hierarchy equations o

V. E. Viola, K. Kwiatkowski, S. J. Yennello, J. B. Natowitz

In [1,2]the observed decrease in spectral peak energies of IMFs emitted from hot nuclei was interpreted in terms of a breakup density that decreased with increasing energy. Subsequently, Raduta et al. [3] performed MMM simulations that showed decreasing spectral peaks could be obtained at constant density. In this letter we examine this apparent inconsistenc

Martin Hammele, Walter Zimmermann

The effects of a spatially periodic forcing on an oscillating chemical reaction as described by the Lengyel-Epstein model are investigated. We find a surprising competition between two oscillating patterns, where one is harmonic and the other subharmonic with respect to the spatially periodic forcing. The occurrence of a subharmonic pattern is remarkable as

Daniel Scholz, Michael Weyrauch

We provide a simple method for the calculation of the terms c_n in the Zassenhaus product $e^{a+b}=e^a e^b \prod_{n=2}^{\infty} e^{c_n}$ for non-commuting a and b. This method has been implemented in a computer program. Furthermore, we formulate a conjecture on how to translate these results into nested commutators. This conjecture was checked up to order n=

Dikanaina Harrivel

We define covariantly a deformation of a given algebra, then we will see how it can be related to a deformation quantization of a class of observables in Quantum Field Theory. Then we will investigate the operator order related to this deformation quantization.

Dikanaina Harrivel

In a first part we study the phi^{p+1}--field theory from the classical point of view. Using Butcher series we compute explicitly the perturbative expansion of the solutions and we prove that this expansion converges if the coupling constant is small enough. Then we show that we can formally recover the Heisenberg&#39;s interacting quantum field directly fro

M. Gubinelli

We establish a representation of a class of solutions of 3d Navier-Stokes equations in $\R^3$ using sums over rooted trees. We study the convergence properties of this series recovering in a simplified manner some results obtained recently by Sinai and other known results for solutions in spaces of pseudo-measures introduced initially by Le Jan and Sznitman.

Carlos Castano-Bernard

In this paper we study a geometric coding algorithm for indefinite binary quadratic forms Q for the congruence subgroup Γ^0(N), with respect to the usual fundamental domain FN, where N is assumed prime. The cycles Q_1, . . ., Q_n that this algorithm produces are such that the the corresponding paths γ_1, . . ., γ_n in the Riemann surface X0(N)(C) have a nice

Jose F. Alves, Vilton Pinheiro

We consider both hyperbolic sets and partially hyperbolic sets attracting a set of points with positive volume in a Riemannian manifold. We obtain several results on the topological structure of such sets for diffeomorphisms whose differentiability is bigger than one. We show in particular that there are no partially hyperbolic horseshoes with positive volum

Stefania Gabelli, Giampaolo Picozza

We introduce and study the notion of $\star$-stability with respect to a semistar operation $\star$ defined on a domain $R$; in particular we consider the case where $\star$ is the $w$-operation. This notion allows us to generalize and improve several properties of stable domains and totally divisorial domains.

Iana I. Anguelova

In this paper we use a bicharacter construction to define an $H_D$-quantum vertex algebra structure corresponding to the quantum vertex operators describing certain classes of symmetric polynomials.

Taekyun Kim

Recently (see [1]) I has introduced an interesting the Euler-Barnes multiple zeta function. In this paper we construct the q-analogue of Euler-Barnes multiple zeta function which interpolates the q-analogue of Frobenius-Euler numbers of higher order at negative integers.

Haisheng Li

We use a result of Barron, Dong and Mason to give a natural isomorphism between the category of twisted modules and the category of quasi-modules of a certain type for a general vertex operator algebra.

Antonio J. Di Scala Andrea Loi

With the aid of the theory of Jordan triple systems, we construct an explicit bi-symplectomorphism between a Hermitian symmetric space of non-compact type and $\C^n$ equipped with both the flat Kaehler-form and the Fubini-Study form. Our symplectomorphism is an explicit version of the symplectomorphism between Kaehler manifolds with non positive radial curva

Franz Luef

Around 1980 Connes extended the notions of geometry to the non-commutative setting. Since then {\it non-commutative geometry} has turned into a very active area of mathematical research. As a first non-trivial example of a non-commutative manifold Connes discussed subalgebras of rotation algebras, the so-called {\it non-commutative tori}. In the last two dec

E. Carlini, M. V. Catalisano

In this paper we study existence and uniqueness of rational normal curves in $\PP^n$ passing through $p$ points and intersecting $l$ codimension two linear spaces in $n-1$ points each. If $p+l=n+3$ and the points and the linear spaces are generic, one expects the curve to exist, but this is not always the case. Our main result precisely describes in which ca

Jean-François Angers, Peter T. Kim

Bayesian methods are developed for the multivariate nonparametric regression problem where the domain is taken to be a compact Riemannian manifold. In terms of the latter, the underlying geometry of the manifold induces certain symmetries on the multivariate nonparametric regression function. The Bayesian approach then allows one to incorporate hierarchical

P. E. Jupp

Classes of coordinate-invariant omnibus goodness-of-fit tests on compact Riemannian manifolds are proposed. The tests are based on Giné&#39;s Sobolev tests of uniformity. A condition for consistency is given. The tests are illustrated by an example on the rotation group $\mathit{SO}(3)$.

T. Tony Cai, Mark G. Low

Estimation of a quadratic functional over parameter spaces that are not quadratically convex is considered. It is shown, in contrast to the theory for quadratically convex parameter spaces, that optimal quadratic rules are often rate suboptimal. In such cases minimax rate optimal procedures are constructed based on local thresholding. These nonquadratic proc

Dikanaina Harrivel

We show how solutions of a non--linear differential equation can be written as sum indexed by planar trees: the Butcher series. Then we use that property in order to control non--linear differential equation. We show that if the linearized system is controllable then the system itself is controllable if the nonlinear term is small enough and we express expli

Fang Yao, Hans-Georg Müller, Jane-Ling Wang

We propose nonparametric methods for functional linear regression which are designed for sparse longitudinal data, where both the predictor and response are functions of a covariate such as time. Predictor and response processes have smooth random trajectories, and the data consist of a small number of noisy repeated measurements made at irregular times for

Peter Hall, Joel L. Horowitz

We suggest two nonparametric approaches, based on kernel methods and orthogonal series to estimating regression functions in the presence of instrumental variables. For the first time in this class of problems, we derive optimal convergence rates, and show that they are attained by particular estimators. In the presence of instrumental variables the relation

Mong Lung Lang

We determine the normalisers of congruence subgroups of $G_5$.

Thomas Y. Hou, Ruo Li

We prove the nonexistence of local self-similar solutions of the three dimensional incompressible Navier-Stokes equations. The local self-similar solutions we consider here are different from the global self-similar solutions. The self-similar scaling is only valid in an inner core region which shrinks to a point dynamically as the time, $t$, approaches the

Carlos Gutierrez, Roland Rabanal

The main result given in Theorem~1.1 is a condition for a map $X$, defined on the complement of a disk $D$ in R^2 with values in R^2, to be extended to a topological embedding of R^2, not necessarily surjective. The map $X$ is supposed to be just differentiable with the condition that, for some $e>0,$ at each point the eigenvalues of the differential do not

Alexander Burstein, Isaiah Lankham

Patience Sorting is a combinatorial algorithm that can be viewed as an iterated, non-recursive form of the Schensted Insertion Algorithm. In recent work the authors have shown that Patience Sorting provides an algorithmic description for permutations avoiding the barred (generalized) permutation pattern $3-\bar{1}-42$. Motivated by this and a recently formul

Shinzo Bannai, Hiro-o Tokunaga

In this paper we introduce two versal $S_4$ coverings, and show that the two are birationaly distinct, i.e. there exists no $S_4$ equivariant birational map between them. We also introduce two versal $A_5$ coverings and show that the two are birationaly distinct also. As a corollary we obtain that there are at least three non-conjugate embbedings of $S_4$ (r

David Hernandez

We prove the Kirillov-Reshetikhin conjecture for all untwisted quantum affine algebras : we prove that the character of Kirillov-Reshetikhin modules solve the Q-system and we give an explicit formula for the character of their tensor products. In the proof we show that the Kirillov-Reshetikhin modules are special in the sense of monomials and that their q-ch

Takeo Nishinou, Bernd Siebert

We show that the counting of rational curves on a complete toric variety that are in general position to the toric prime divisors coincides with the counting of certain tropical curves. The proof is algebraic-geometric and relies on degeneration techniques and log deformation theory. This generalizes results of Mikhalkin obtained by different methods in the

M. Buric, T. Grammatikopoulos, J. Madore, G. Zoupanos

A gravitational field can be defined in terms of a moving frame, which when made noncommutative yields a preferred basis for a differential calculus. It is conjectured that to a linear perturbation of the commutation relations which define the algebra there corresponds a linear perturbation of the gravitational field. This is shown to be true in the case of

Nikolay Gromov, Vladimir Kazakov, Kazuhiro Sakai, Pedro Vieira

We study the quantum Bethe ansatz equations in the O(2n) sigma-model for hysical particles on a circle, with the interaction given by the Zamolodchikovs&#39; S-matrix, in view of its application to quantization of the string on the S^{2n-1} x R_t space. For a finite number of particles, the system looks like an inhomogeneous integrable O(2n) spin chain. Simi

J. Grain, A. Barrau

Quantum fields exhibit non-trivial behaviours in curved space-times, especially around black holes or when a cosmological constant is added to the field equations. A new scheme, based on the Wentzel-Kramers-Brillouin (WKB) approximation is presented. The main advantage of this method is to allow for a better physical understanding of previously known results

Alexander A. Chernitskii

Electromagnetic particle is considered as appropriate particle solution of nonlinear electrodynamics. Mass, spin, charge, and dipole moment for the electromagnetic particle are defined. Classical motion equations for massive charged particle with spin and dipole moment are obtained from integral conservation laws for the field.

T. Klose, K. Zarembo

We compute the exact S-matrix and give the Bethe ansatz solution for three sigma-models which arise as subsectors of string theory in AdS(5)xS(5): Landau-Lifshitz model (non-relativistic sigma-model on S(2)), Alday-Arutyunov-Frolov model (fermionic sigma-model with su(1|1) symmetry), and Faddeev-Reshetikhin model (string sigma-model on S(3)xR).

S. E. M. Nooij

This thesis provides a classification of the chiral content of the heterotic $\mathbbm{Z}_2 \times \mathbbm{Z}_2$ orbifold models. We show that the chiral content of the heterotic $\mathbbm{Z}_2 \times \mathbbm{Z}_2$ orbifold models at any point in the moduli space can be described by a free fermionic model. We present a direct translation between the orbifo

S. Bellucci, D. O&#39;Reilly

We reconsider the well-known issue of string corrections to Supergravity theory. Our treatment is carried out to second order in the string slope parameter. We establish a procedure for solving the Bianchi identities in the non minimal case, and we solve a long standing problem in the perturbative expansion of D=10, N=1 string corrected Supergravity, obtaini

Y. M. Cho, D. G. Pak, M. L. Walker

The effects of light propagation in constant magnetic and electric backgrounds are considered in the framework of the effective action approach. We use the exact analytic series representation for the one-loop effective action of QED and apply it to the birefringence effect. Analytical results for the light velocity modes are obtained for weak and strong fie

C. Aydin, M. Bayar, A. H. Yilmaz

The coupling constant of a0-->rho-gamma and f0-->rho-gamma decays are calculated using 3-point sum rule. We estimate the coupling constant g_a0-rho-gamma and g_f0-rho-gamma which are an essential ingredient in the analysis of physical processes involving isoscalar f0(980) and isovector a0(980) mesons.

V. Ravindran

We present threshold enhanced QCD corrections to inclusive processes such as Deep inelastic scattering, Drell-Yan process and Higgs productions through gluon fusion and bottom quark annihilation processes using the resummed cross sections. The resummed cross sections are derived using renormalisation group invariance and mass factorisation theorem that these

A. Jakovac, P. Petreczky, Konstantin Petrov, A. Velytsky

We study charmonium correlators and spectral functions at zero and finite temperature using anisotropic lattices at several different lattice spacings. We find evidence for survival of 1S charmonia states at leas till $1.5T_c$ and dissolution of 1P states at $1.16T_c$.

M. Battaglia, T. Barklow, M. Peskin, Y. Okada

This note presents a list of physics processes for benchmarking the performance of proposed ILC detectors. This list gives broad coverage of the required physics capabilities of the ILC experiments and suggests target accuracies to be achieved. A reduced list of reactions, which capture within a very economical set the main challenges put by the ILC physics

Thomas Marlow

We attempt a justification of a generalisation of the consistent histories programme using a notion of probability that is valid for all complete sets of history propositions. This consists of introducing Cox&#39;s axioms of probability theory and showing that our candidate notion of probability obeys them. We also give a generalisation of Bayes&#39; theorem

Siddharth Ray, Michelle Effros, Muriel Medard, Ralf Koetter

We examine the issue of separation and code design for networks that operate over finite fields. We demonstrate that source-channel (or source-network) separation holds for several canonical network examples like the noisy multiple access channel and the erasure degraded broadcast channel, when the whole network operates over a common finite field. This robu

Joy Mukherjee, Srinidhi Varadarajan

We recommend a programming construct - availability check - for programs that need to automatically adjust to presence or absence of segments of code. The idea is to check the existence of a valid definition before a function call is invoked. The syntax is that of a simple &#39;if&#39; statement. The vision is to enable customization of application functiona

L. Brey, M. J. Calderon, S. Das Sarma, F. Guinea

A mean field approximation of a model for double perovskites that takes into account the coupling between itinerant electron spins and localized spins is developed. As in previously reported theoretical results, and contrary to experimental observation, the critical temperature is suppressed for large electron density. An effective Heisenberg model reveals t

Chang-Yu Hou, Claudio Chamon

We study a tunneling geometry defined by a single point-contact constriction that brings to close vicinity two points sitting at the same edge of a quantum Hall liquid, shortening the trip between the otherwise spatially separated points along the normal chiral edge path. This ``wormhole&#39;&#39;-like geometry allows for entrapping bulk quasiparticles betwe

Oded Agam, A. V. Andreev, B. Spivak

We develop a general method for calculating statistical properties of the speckle pattern of coherent waves propagating in disordered media. In some aspects this method is similar to the Boltzmann-Langevin approach for the calculation of classical fluctuations. We apply the method to the case where the incident wave experiences many small angle scattering ev

Craig J. Fennie, Karin M. Rabe

We have studied ferroelectricity in Dion-Jacobson CsBiNb$_2$O$_7$ from first principles. Using group-theoretical analysis and first-principles density functional calculations of the total energy and phonons, we perform a systematic study of the energy surface around a paraelectric prototypic phase. Our results suggest that CsBiNb$_2$O$_7$ is a ferroelectric

F. Aryasetiawan, K. Karlsson, O. Jepsen, U. Schonberger

The Hubbard \emph{U} of the \emph{3d} transition metal series as well as SrVO$_{3}$, YTiO$_{3}$, Ce and Gd has been estimated using a recently proposed scheme based on the random-phase approximation. The values obtained are generally in good accord with the values often used in model calculations but for some cases the estimated values are somewhat smaller t

Natascia Andrenacci, Federico Corberi, Eugenio Lippiello

We consider the modified Ising model introduced by de Oliveira et al. [J.Phys.A {\bf 26}, 2317 (1993)], where the temperature depends locally on the spin configuration and detailed balance and local equilibrium are not obeyed. We derive a relation between the linear response function and correlation functions which generalizes the fluctuation-dissipation the

Thomas John, Dirk Rannacher, Andreas Engel

We study the influence of surface tension on the shape of the conical miniscus built up by a magnetic fluid surrounding a current-carrying wire. Minimization of the total energy of the system leads to a singular second order boundary value problem for the function $ζ(r)$ describing the axially symmetric shape of the free surface. An appropriate transformatio

Hannes Raebiger, Maria Ganchenkova, Juhani von Boehm

The Ga vacancy mediated microstructure evolution of (Ga,Mn)As during growth and post-growth annealing is studied using a multi-scale approach. The migration barriers for the Ga vacancies and substitutional Mn together with their interactions are calculated from first principles, and temporal evolution at temperatures ranging from 200 to 350$^\circ$C is studi

Ginestra Bianconi, Tobias Galla, Matteo Marsili

We show that the introduction of Tobin taxes in agent-based models of currency markets can lead to a reduction of speculative trading and reduce the magnitude of exchange rate fluctuations at intermediate tax rates. In this regime revenues for the market maker obtained from speculators are maximal. We here focus on Minority Game models of markets, which are

P. P. Boriskov, A. L. Pergament, A. A. Velichko, G. B. Stefanovich

The proposed switching mechanism is based on an electronically-induced metal-insulator transition occurring in conditions of the excess non-equilibrium carrier density under the applied electric field. First, this mechanism is developed on the basis of a phenomenological approach. This model not only allows the qualitative description of the switching mechan

L. L. Bonilla, R. Escobedo, G. Dell&#39;Acqua

A numerical study of domain wall relocation during voltage switching with different ramping times is presented for weakly coupled, doped semiconductor superlattices exhibiting multistable domain formation in the first plateau of their current-voltage characteristics. Stable self-oscillations of the current at the end of stable stationary branches of the curr

L. Delfini, S. Lepri, R. Livi, A. Politi

In the present Letter we present an analytical and numerical solution of the self-consistent mode-coupling equations for the problem of heat conductivity in one-dimensional systems. Such a solution leads us to propose a different scenario to accomodate the known results obtained so far for this problem. More precisely, we conjecture that the universality cla

David Cubero, Jesús Casado-Pascual, Azucena Alvarez, Manuel Morillo

We investigate a dissipative, deterministic ratchet model in the overdamped regime driven by a {\it rectangular force}. Extensive numerical calculations are presented in a diagram depicting the drift velocity as a function of a wide range of the driving parameter values. We also present some theoretical considerations which explain some features of the menti

N. Stojic, N. Binggeli, M. Altarelli

We report calculations indicating the presence of a surface magnetic moment for Rh(001), motivated by the detection of a finite moment by magnetic linear dichroism experiments. We show that, while the density functional with the local density or generalized gradient approximations (LDA and GGA) for exchange and correlation yields a non-magnetic ground state,

K. Hamaya, T. Taniyama, T. Koike, Y. Yamazaki

We study the effect of the shape anisotropy on the magnetic domain configurations of a ferromagnetic semiconductor (Ga,Mn)As/GaAs(001) epitaxial wire as a function of temperature. Using magnetoresistance measurements, we deduce the magnetic configurations and estimate the relative strength of the shape anisotropy compared with the intrinsic anisotropies. Sin

A. Gabrielli, T. Baertschiger, M. Joyce, B. Marcos

We study the statistics of the force felt by a particle in the class of spatially correlated distribution of identical point-like particles, interacting via a $1/r^2$ pair force (i.e. gravitational or Coulomb), and obtained by randomly perturbing an infinite perfect lattice. In the first part we specify the conditions under which the force on a particle is a

T. C. Kim, J. -M. Lee, Y. Kim, D. Y. Noh

We study the growth of the Fe films on GaAs(100) at a low temperature, 140 K, by $in$-$situ$ UHV x-ray reflectivity using synchrotron radiation. We find rough surface with the growth exponent, $β_S$ = 0.51$\pm$0.04. This indicates that the growth of the Fe film proceeds via the restrictive relaxation due to insufficient thermal diffusion of the adatoms. The

G. R. Berdiyorov, M. V. Milošević, F. M. Peeters

Novel behavior of the critical current density $j_{c}$ of a regularly perforated superconducting film is found, as a function of applied magnetic field $H$. Previously pronounced peaks of $j_{c}$ at matching fields were always found to decrease with increasing $H$. Here we found a {\it reversal of this behavior} for particular geometrical parameters of the a

Gabriel Autes, Cyrille Barreteau, Daniel Spanjaard, Marie-Catherine Desjonqueres

The magnetic properties of iron (spin and orbital magnetic moments, magnetocrystalline anisotropy energy) in various geometries and dimensionalities are investigated by using a parametrized tight-binding model in an $s$, $p$ and $d$ atomic orbital basis set including spin polarization and the effect of spin-orbit coupling. The validity of this model is well

Gavin E. Crooks

What is the best description that we can construct of a thermodynamic system that is not in equilibrium, given only one, or a few, extra parameters over and above those needed for a description of the same system at equilibrium? Here, we argue the most appropriate additional parameter is the non-equilibrium entropy of the system, and that we should not attem

Gao Xianlong, M. Polini, B. Tanatar, M. P. Tosi

Interacting two-component Fermi gases loaded in a one-dimensional (1D) lattice and subject to harmonic trapping exhibit intriguing compound phases in which fluid regions coexist with local Mott-insulator and/or band-insulator regions. Motivated by experiments on cold atoms inside disordered optical lattices, we present a theoretical study of the effects of a

E. Ben-Naim, P. L. Krapivsky

We study how weak disorder affects the growth of the Fibonacci series. We introduce a family of stochastic sequences that grow by the normal Fibonacci recursion with probability 1-epsilon, but follow a different recursion rule with a small probability epsilon. We focus on the weak disorder limit and obtain the Lyapunov exponent, that characterizes the typica

Gavin E. Crooks, Christopher Jarzynski

We consider the adiabatic and quasi-static compression of a dilute classical gas, confined in a piston and initially equilibrated with a heat bath. We find that the work performed during this process is described statistically by a gamma distribution. We use this result to show that the model satisfies the non-equilibrium work and fluctuation theorems, but n

Tetsuo Deguchi

We discuss irreducible highest weight representations of the sl(2) loop algebra and reducible indecomposable ones in association with the sl(2) loop algebra symmetry of the six-vertex model at roots of unity. We formulate an elementary proof that every highest weight representation with distinct evaluation parameters is irreducible. We present a general crit

R. L. Badzey, P. Mohanty

Stochastic resonance is a counter-intuitive concept[1,2], ; the addition of noise to a noisy system induces coherent amplification of its response. First suggested as a mechanism for the cyclic recurrence of ice ages, stochastic resonance has been seen in a wide variety of macroscopic physical systems: bistable ring lasers[3], SQUIDs[4,5], magnetoelastic rib

Young L. Kim, Prabhakar Pradhan, Hariharan Subramanian, Yang Liu

We exploit low spatial coherence illumination to dephase time-reversed partial waves outside its finite coherence area, which virtually creates a controllable coherence volume and isolates the minimal number of scattering events from higher order scattering in enhanced backscattering (EBS, also known as coherent backscattering) of light. We report the first

A. C. D. van Enter, S. B. Shlosman

In this contribution we discuss the occurrence of first-order transitions in temperature in various short-range lattice models with a rotation symmetry. Such transitions turn out to be widespread under the condition that the interaction potentials are sufficiently nonlinear.

Carlo Di Castro, Roberto Raimondi

These lectures provide an introduction to the theory of disordered interacting electron systems. In particular, we concentrate on those aspects which are fundamental for the problem of the metal-insulator transition due to the interplay of disorder and interaction. After reviewing the problem of disordered non-interacting electrons, we examine the past and r

Maria K. Koleva, L. A. Petrov

The properties of the fluctuations large enough to induce bifurcations at open chemical systems at steady constraints are studied. The fluctuations that come from the diffusion-induced noise are considered. It is a generic for the surface reactions driving mechanism of fluctuations whose distinctive property is that it generates bounded fluctuations at any v

Kevin Heng, Richard McCray, Svetozar A. Zhekov, Peter M. Challis

We present new (2004 July) G750L and G140L Space Telescope Imaging Spectrograph (STIS) data of the H-alpha and Ly-alpha emission from supernova remnant (SNR) 1987A. With the aid of earlier data, from Oct 1997 to Oct 2002, we track the local evolution of Ly-alpha emission and both the local and global evolution of H-alpha emission. In addition to emission whi

T. Roy Choudhury, A. Ferrara

The study of cosmic reionization has acquired increasing significance over the last few years because of various reasons. On the observational front, we now have good quality data of different types at high redshifts (quasar absorption spectra, radiation backgrounds at different frequencies, cosmic microwave background polarization, Ly-alpha emitters and so

Jeremy L. Tinker, David H. Weinberg, Michael S. Warren

(Abridged) We investigate the power of void statistics to constrain galaxy bias and the amplitude of dark matter fluctuations. We use the halo occupation distribution (HOD) framework to describe the relation between galaxies and dark matter. After choosing HOD parameters that reproduce the mean space density n_gal and projected correlation function w_p measu

Tristan L. Smith, Elena Pierpaoli, Marc Kamionkowski

Primordial gravitational waves (GWs) with frequencies > 10^{-15} Hz contribute to the radiation density of the Universe at the time of decoupling of the cosmic microwave background (CMB). The effects of this GW background on the CMB and matter power spectra are identical to those due to massless neutrinos, unless the initial density-perturbation amplitude fo

Claude Carignan, Laurent Chemin, Walter K. Huchtmeier, Felix J. Lockman

New HI observations of Messier 31 (M31) obtained with the Effelsberg and Green Bank 100-m telescopes make it possible to measure the rotation curve of that galaxy out to ~35 kpc. Between 20 and 35 kpc, the rotation curve is nearly flat at a velocity of ~226 km/s. A model of the mass distribution shows that at the last observed velocity point, the minimum dar

C. Dickinson, S. Casassus, J. L. Pineda, T. J. Pearson

[LPH96]201.663+1.643, a diffuse H{\sc ii} region, has been reported to be a candidate for emission from rapidly spinning dust grains. Here we present Cosmic Background Imager (CBI) observations at 26-36 GHz that show no evidence for significant anomalous emission. The spectral index within the CBI band, and between CBI and Effelsberg data at 1.4/2.7 GHz, is

John C. Hodge

A derivation of a theoretical, time average, cosmic microwave background (CMB), Planckian temperature V of the universe remains a challenge. A scalar potential model (SPM) that resulted from considerations of galaxy cells is applied to deriving a value for V. The heat equation is solved for a cell with the boundary conditions of SPM Source and Sink character

Andrea Comastri, Marcella Brusa, Roberto Gilli

The shape and the intensity of the 6.4 keV iron line bring unique information on the geometrical and physical properties of the supermassive black hole and the surrounding accreting gas at the very center of Active Galactic Nuclei. While there are convincing evidences of a relativistically broadened iron line in a few nearby bright objects, their properties

Eric M. Huff, Steven Stahler

We examine the pattern of star birth in the Orion Nebula Cluster (ONC), with the goal of discerning the cluster&#39;s formation mechanism. Outside of the Trapezium, the distribution of stellar masses is remarkably uniform, and is not accurately described by the field-star initial mass function. The deconvolved, three-dimensional density of cluster members pe

B. Parise, C. Ceccarelli, A. G. G. M. Tielens, A. Castets

Context : Despite the low cosmic abundance of deuterium (D/H ~ 1e-5), large degrees of deuterium fractionation in molecules are observed in star forming regions with enhancements that can reach 13 orders of magnitude, which current models have difficulties to account for. Aims : Multi-isotopologue observations are a very powerful constraint for chemical mode

N. G. Guseva, Y. I. Izotov, T. X. Thuan

We have used the Balmer and Paschen jumps to determine the temperatures of the H+ zones of a total sample of 47 H II regions. The Balmer jump was used on MMT spectrophotometric data of 22 low-metallicity H II regions in 18 blue compact dwarf (BCD) galaxies and of one H II region in the spiral galaxy M101. The Paschen jump was used on spectra of 24 H II emiss

Cintia Quireza, Robert T. Rood, Dana S. Balser, T. M. Bania

We report radio recombination line (RRL) and continuum observations of a sample of 106 Galactic HII regions made with the NRAO 140 Foot radio telescope in Green Bank, WV. We believe this to be the most sensitive RRL survey ever made for a sample this large. Most of our source integration times range between 6 and 90 hours which yield typical r.m.s. noise lev

S. -J. Paardekooper, G. Mellema

We study the dynamics of gas and dust in a protoplanetary disk in the presence of embedded planets. We investigate the conditions for dust-gap formation in terms of particle size and planetary mass. We also monitor the amount of dust that is accreted by the planet relative to the amount of gas, which is an important parameter in determining the enrichment of

E. Kuulkers, S. Shaw, S. Brandt, J. Chenevez

The Galactic Bulge region is a rich host of variable high-energy point sources. These sources include bright and relatively faint X-ray transients, X-ray bursters, persistent neutron star and black-hole candidate binaries, X-ray pulsars, etc.. We have a program to monitor the Galactic Bulge region regularly and frequently with the gamma-ray observatory INTEG

Thomas H. Reiprich, Daniel S. Hudson, Thomas Erben, Craig L. Sarazin

We report on the status of our effort to constrain the nature of dark energy through the evolution of the cluster mass function. Chandra temperature profiles for 31 clusters from a local cluster sample are shown. The X-ray appearance of the proto supermassive binary black hole at the center of the cluster Abell 400 is described. Preliminary weak lensing resu

R. Smiljanic, B. Barbuy, J. R. De Medeiros, A. Maeder

Many observational results seem to indicate more efficient mixing processes in intermediate mass stars (5-20 M$_{\odot}$) than the expected by the standard models. These processes are usually thought to be caused by stellar rotation. Our recent analysis of 19 evolved intermediate mass stars has found them to display different efficiencies of internal mixing.

S. Van Loo, M. C. Runacres, R. Blomme

We present a model for the non-thermal radio emission from presumably single O stars, in terms of synchrotron emission from relativistic electrons accelerated in wind-embedded shocks. These shocks are associated with an unstable, chaotic wind. The main improvement with respect to earlier models is the inclusion of the radial dependence of the shock velocity

M. Romero-Gomez, J. J. Masdemont, E. Athanassoula, C. Garcia-Gomez

We propose a new theory for the formation of rR_1 ring structures, i.e. for ring structures with both an inner and an outer ring, the latter having the form of ``8&#39;&#39;. We propose that these rings are formed by material from the stable and unstable invariant manifolds associated with the Lyapunov orbits around the equilibrium points of a barred galaxy.

Keith S. Noll

The discovery of binaries in each of the major populations of minor bodies in the solar system is propelling a rapid growth of heretofore unattainable physical information. The availability of mass and density constraints for minor bodies opens the door to studies of internal structure, comparisons with meteorite samples, and correlations between bulk- physi

A. Beelen, P. Cox, D. J. Benford, C. D. Dowell

We report detections of six high-redshift (1.8 < z < 6.4), optically luminous, radio-quiet quasars at 350 micron, using the SHARC II bolometer camera at the Caltech Submillimeter Observatory. Our observations double the number of high-redshift quasars for which 350 micron photometry is available. By combining the 350 micron measurements with observations at