May 2005 arXiv papers — page 10

M. Woods, R. Erickson, J. Frisch, C. Hast

The SLAC Linac can deliver damped bunches with ILC parameters for bunch charge and bunch length to End Station A. A 10Hz beam at 28.5 GeV energy can be delivered there, parasitic with PEP-II operation. We plan to use this facility to test prototype components of the Beam Delivery System and Interaction Region. We discuss our plans for this ILC Test Facility

Annalisa Fabretti, Marcel Ausloos

Recurrence Plot (RP) and Recurrence Quantification Analysis RQA) are signal numerical analysis methodologies able to work with non linear dynamical systems and non stationarity. Moreover they well evidence changes in the states of a dynamical system. It is shown that RP and RQA detect the critical regime in financial indices (in analogy with phase transition

A Jannetta, J C Jackson, C J Kotre, I P Birch

An image restoration approach based on a Bayesian maximum entropy method (MEM) has been applied to a radiological image deconvolution problem, that of reduction of geometric blurring in magnification mammography. The aim of the work is to demonstrate an improvement in image spatial resolution in realistic noisy radiological images with no associated penalty

D. Mugnai

The oblique incidence of a Bessel beam on a dielectric slab with refractive index n1 surrounded by a medium of a refractive index n>n1 may be studied simply by expanding the Bessel beam into a set of plane waves forming the same angle with the axis of the beam. In the present paper we examine a Bessel beam that impinges at oblique incidence onto a layer in s

Chang-Kui Duan, Michael F. Reid

For emitters in a medium, different macroscopic or microscopic theoretical models predict substantially different dependencies of the spontaneous emission lifetime on refractive index. Various measurements have been carried out on Eu$^{3+}$, Ce$^{3+}$ and Nd$^{3+}$ ions, and quantum dots in different surrounding medial. The dependence of the spontaneous emis

Jones T. K. Wan, C. T. Chan

Ordinary metallic photonic crystals (PCs) have photonic band gaps in which the density of states (DOS) is strongly modified. Thermal emission of photons can be suppressed and enhanced accordingly. We consider the thermal emission characteristics of a metallic photonic crystal slab with a tunable thickness which in the thick limit approaches that of a photoni

Ch. Hoffmann, M. Lücke, A. Pinter

We present numerical simulations of vortices that appear via primary bifurcations out of the unstructured circular Couette flow in the Taylor-Couette system with counter-rotating as well as with co-rotating cylinders. The full, time dependent Navier-Stokes equations are solved with a combination of a finite difference and a Galerkin method for a fixed axial

Chang-Kui Duan, Yungui Gong, Hui-Ning Dong, Michael F. Reid

Effective interaction operators usually act on a restricted model space and give the same energies (for Hamiltonian) and matrix elements (for transition operators etc.) as those of the original operators between the corresponding true eigenstates. Various types of effective operators are possible. Those well defined effective operators have been shown being

Chang-Kui Duan, Michael F. Reid, Gang Ruan, hui-Ning Dong

Effective operators needed in single-beam two-photon transition calculations have been represented with modified Goldstone diagrams similar to the type suggested by Duan and co-workers [J. Chem. Phys. 121, 5071 (2004) ]. The rules to evaluate these diagrams are different from those for effective Hamiltonian and one-photon transition operators. It is verified

Chang-Kui Duan, Gang Ruan, Michael F. Reid

Perturbative contributions to single-beam two-photon transition rates may be divided into two types. The first, involving low-energy intermediate states, require a high-order perturbation treatment, or an exact diagonalization. The other, involving high energy intermediate states, only require a low-order perturbation treatment. We show how to partition the

John D. Perreault, Alexander D. Cronin

The development of nanotechnology and atom optics relies on understanding how atoms behave and interact with their environment. Isolated atoms can exhibit wave-like (coherent) behaviour with a corresponding de Broglie wavelength and phase which can be affected by nearby surfaces. Here an atom interferometer is used to measure the phase shift of Na atom waves

V. I. Abrosimov, A. Dellafiore, F. Matera

A semiclassical theory of linear response in finite Fermi systems, based on the Vlasov equation, and its applications to the study of isoscalar vibrations in heavy nuclei are reviewed. It is argued that the Vlasov equation can be used to study the response of small quantum systems like (heavy) nuclei in regimes for which the finite size of the system is more

T. Christiansen, P. D. Hislop

We show that the resonance counting function for a Schrödinger operator has maximal order of growth for generic sets of real-valued, or complex-valued, $L^\infty$-compactly supported potentials.

Jungyoon Byun

``Bonsai'' Hopf algebras, introduced here, are generalizations of Connes-Kreimer Hopf algebras, which are motivated by Feynman diagrams and renormalization. We show that we can find operad structure on the set of bonsais. We introduce a new differential on these bonsai Hopf algebras, which is inspired by the tree differential. The cohomologies of the

Jenny Harrison

These draft notes are from a graduate course given by the author in Berkeley during the spring semester of 2005. They cover the basic ideas of a new, geometric approach to geometric measure theory. They begin with a new theory of exterior calculus at a single point. This infinitesimal theory extends, by linearity, to a discrete exterior theory, based at fini

George Panasyuk, John C. Schotland, Vadim A. Markel

A novel method for solving the linear radiative transport equation (RTE) in a three-dimensional homogeneous medium is proposed and illustrated with numerical examples. The method can be used with an arbitrary phase function A(s,s') with the constraint that it depends only on the angle between the angular variables s and s'. This corresponds to spheri

Luc Lapointe, Jennifer Morse

We study k-Schur functions characterized by k-tableaux, proving combinatorial properties such as a k-Pieri rule and a k-conjugation. This new approach relies on developing the theory of k-tableaux, and includes the introduction of a weight-permuting involution on these tableaux that generalizes the Bender-Knuth involution. This work lays the groundwork neede

Jerry E. Vaughan

S. Garcia-Ferreira and H. Ohta gave a construction that was intended to produce a tau-pseudocompact space, which has a regular-closed zero set A and a regular-closed C-embedded set B such that neither A nor B is tau-pseudocompact. We show that although their sets A, B are not regular-closed, there are at least two ways to make their construction work to give

E. L. Allgower, D. J. Bates, A. J. Sommese, C. W. Wampler

Nonlinear two-point boundary value problems arise in numerous areas of application. The existence and number of solutions for various cases has been studied from a theoretical standpoint. These results generally rely upon growth conditions of the nonlinearity. However, in general, one cannot forecast how many solutions a boundary value problem may possess or

Dragos Ghioca

We prove that the group of rational points of a non-isotrivial elliptic curve defined over the perfect closure of a function field in one variable over a finite field is finiteley generated.

Martin R Bridson, James Howie

Let $\G$ be a limit group, $S\subset\G$ a subgroup, and $N$ the normaliser of $S$. If $H_1(S,\mathbb Q)$ has finite $\Q$-dimension, then $S$ is finitely generated and either $N/S$ is finite or $N$ is abelian. This result has applications to the study of subdirect products of limit groups.

Murray Elder, Vince Vatter

We recount problems, questions and conjectures that arose during a problem session of the Third International Conference on Permutation Patterns, University of Florida, March 7-11, 2005.

B. V. Rajarama Bhat, Santanu Dey, Joachim Zacharias

Given a contractive tuple of Hilbert space operators satisfying certain $A$-relations we show that there exists a unique minimal dilation to generators of Cuntz-Krieger algebras or its extension by compact operators. This Cuntz-Krieger dilation can be obtained from the classical minimal isometric dilation as a certain maximal $A$-relation piece. We define a

Daniel Azagra, Juan Ferrera

We show how an operation of inf-convolution can be used to approximate convex functions with $C^{1}$ smooth convex functions on Riemannian manifolds with nonpositive curvature (in a manner that not only is explicit but also preserves some other properties of the original functions, such as ordering, symmetries, infima and sets of minimizers), and we give som

Victor Rivero

We prove that the upward ladder height subordinator $H$ associated to a real valued Lévy process $ξ$ has Laplace exponent $ϕ$ that varies regularly at $\infty$ (resp. at 0) if and only if the underlying Lévy process $ξ$ satisfies Sinai's condition at 0 (resp. at $\infty$). Sinai's condition for real valued Lévy processes is the continuous time analog

Yelena Smagina, Moshe Sheintuch

This paper considers new approach to control a stationary inhomogeneous planar front solution of a nonlinear parabolic two-dimensional distributed (reaction-diffusion) system, by using a gain point-sensor control with actuators that have the simplest possible spatial dependence. The method is based on multivariable root-locus technique for the finite-dimensi

Franck Barthe, Patrick Cattiaux, Cyril Roberto

If a random variable is not exponentially integrable, it is known that no concentration inequality holds for an infinite sequence of independent copies. Under mild conditions, we establish concentration inequalities for finite sequences of $n$ independent copies, with good dependence in $n$.

E. Martinez-Moro, I. F. Rua

The structure of multivariate semisimple codes over a finite chain ring $R$ is established using the structure of the residue field $\bar R$. Multivariate codes extend in a natural way the univariate cyclic and negacyclic codes and include some non-trivial codes over $R$. The structure of the dual codes in the semisimple abelian case is also derived and some

Jurgen Berndt, Hiroshi Tamaru

We classify, up to orbit equivalence, all cohomogeneity one actions on the hyperbolic planes over the complex, quaternionic and Cayley numbers, and on the complex hyperbolic spaces of dimension greater than two. For the quaternionic hyperbolic spaces of dimension greater than two we reduce the classification problem to a problem in quaternionic linear algebr

Vyacheslav M. Abramov

The paper studies a closed queueing network containing two types of node. The first type (server station) is an infinite server queueing system, and the second type (client station) is a single server queueing system with autonomous service, i.e. every client station serves customers (units) only at random instants generated by strictly stationary and ergodi

Mark B. Villarino

We prove that there are thirteen Archimedean/semiregular polyhedra by using Euler's polyhedral formula.

Vladimir Shpilrain, Alexander Ushakov

Recently, several public key exchange protocols based on symbolic computation in non-commutative (semi)groups were proposed as a more efficient alternative to well established protocols based on numeric computation. Notably, the protocols due to Anshel-Anshel-Goldfeld and Ko-Lee et al. exploited the conjugacy search problem in groups, which is a ramification

YanYan Li

We establish Liouville type theorems for degenerate conformally invariant equations.

Arnaud Beauville

We classify, up to conjugacy, the subgroups of the Cremona group isomorphic to (Z/p)^r, where p is prime and r is maximal.

Bo-Hae Im, Michael Larsen

We give local conditions at the infinite places of a number field K ensuring that the intersection of n quadrics in projective N-space over K, N >> n, satisfies weak approximation.

M. Cvetic, H. Lu, Don N. Page, C. N. Pope

In this paper, which is an elaboration of our results in hep-th/0504225, we construct new Einstein-Sasaki spaces L^{p,q,r_1,...,r_{n-1}} in all odd dimensions D=2n+1\ge 5. They arise by taking certain BPS limits of the Euclideanised Kerr-de Sitter metrics. This yields local Einstein-Sasaki metrics of cohomogeneity n, with toric U(1)^{n+1} principal orbits, a

Jerzy A. Przeszowski

The gauge invariant formulation of Maxwell's equations and the electromagnetic duality transformations are given in the light-front (LF) variables. The novel formulation of the LF canonical quantization, which is based on the kinematic translation generator $P^{+}$ rather then on the Hamiltonian $P^{-}$, is proposed. This canonical quantization is applie

Chris Ford, Jan M. Pawlowski

Fermionic zero modes associated with doubly periodic SU(2) instantons of unit charge are considered. In cases where the action density exhibits two `instanton cores' the zero mode peaks on one of four line-segments joining the two constituents. Which of the four possibilities is realised depends on the fermionic boundary conditions; doubly periodic, doub

Adi Armoni, Timothy J. Hollowood

In pure N=1 supersymmetric Yang-Mills with gauge group SU(N), the domain walls which separate the N vacua have been argued, on the basis of string theory realizations, to be D-branes for the confining string. In a certain limit, this means that a configuration of k parallel domain walls is described by a 2+1-dimensional U(k) gauge theory. This theory has bee

Margaret E Wessling

Recent experimental evidence for the Theta^+(1540) has given rise to much theoretical interest in exotic baryons. The Theta^+ is a baryon that has strangeness S=+1, meaning that it contains an anti-strange quark. Thus it cannot be constructed from three quarks, unlike all other known baryons; it needs at least an extra quark-antiquark pair. It is usually mod

Yu. P. Goncharov

Structure of exact solutions modelling confinement is discussed for SU(3)-Yang-Mills equations and uniqueness of such confining solutions is proved in a certain sense. Relationship of the obtained results to QCD and the confinement mechanism is considered. Incidentally the Wilson confinement criterion for the found solutions is verified and also numerical es

Chan-Chi Chiou, Otto C. W. Kong, Rishikesh D. Vaidya

We present a detailed analysis together with numerical calculations on one-loop contributions to the neutron electric dipole moment from supersymmetry without R parity, focusing on the quark-scalar loop contributions. Complete formulas are given for the various contributions through the quark dipole operators. Analytical expressions illustrating the explicit

Shin Ishida, Muneyuki Ishida, Tomohito Maeda, Masuho Oda

The narrow mesons, DsJ*(2317) and DsJ(2460), observed recently in the final states Ds+ pi0 and Ds*+ pi0 are pointed out to be naturally assigned as the ground-state scalar and axial-vector chiral states in the csbar system, which would newly appear in the covariant U~(12) hadron-classification scheme proposed a few years ago. We predict the comparatively lar

Kostas Orginos, Thomas Blum, Shigemi Ohta

We present a quenched lattice QCD calculation of the first few moments of the polarized and un-polarized structure functions of the nucleon. Our calculations are done using domain wall fermions and the DBW2 gauge action with inverse lattice spacing ~1.3GeV, physical volume approximatelly (2.4 fm)^3, and light quark masses down to about 1/4 the strange quark

J. L. Rosner, CLEO Collaboration

The h_c(1P1) state of charmonium has been observed in the reaction ψ(2S) -> \pi0 h_c -> (γγ)(γη_c) using 3.08 million ψ(2S) decays recorded in the CLEO detector. Data have been analyzed both for the inclusive reaction, where the decay products of the η_c are not identified, and for exclusive reactions, in which η_c decays are reconstructed in seven hadronic

K. Miknaitis

The Sudbury Neutrino Observatory (SNO) has recently completed an analysis of data from the salt phase of the experiment, in which NaCl was added to the heavy-water neutrino target to enhance sensitivity to solar neutrinos. Results from the 391-day salt data set are summarized, including the measured solar neutrino fluxes, the electron energy spectrum from ch

Valery Dryuma

Some properties of eight-dimensional Riemann extension of Minkowsky space-time metric in rotating coordinate system are studied.

Udayan Khuarana

In this paper, a sorting technique is presented that takes as input a data set whose primary key domain is known to the sorting algorithm, and works with an time efficiency of O(n+k), where k is the primary key domain. It is shown that the algorithm has applicability over a wide range of data sets. Later, a parallel formulation of the same is proposed and it

P. C. McGuire, J. Fritsch, J. J. Steil, F. Roethling

A major challenge for the realization of intelligent robots is to supply them with cognitive abilities in order to allow ordinary users to program them easily and intuitively. One way of such programming is teaching work tasks by interactive demonstration. To make this effective and convenient for the user, the machine must be capable to establish a common f

Ravi S. Veerubhotla, Ashutosh Saxena, V. P. Gulati, A. K. Pujari

This work presents two new construction techniques for q-ary Gossip codes from tdesigns and Traceability schemes. These Gossip codes achieve the shortest code length specified in terms of code parameters and can withstand erasures in digital fingerprinting applications. This work presents the construction of embedded Gossip codes for extending an existing Go

Dragos Trinca

Adaptive variable-length codes associate a variable-length codeword to the symbol being encoded depending on the previous symbols in the input string. This class of codes has been recently presented in [Dragos Trinca, arXiv:cs.DS/0505007] as a new class of non-standard variable-length codes. New algorithms for data compression, based on adaptive variable-len

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. Detection of such outliers is important for many applications such as fraud detection and customer migration. Most such applications are high dimensional domains in which the data may contain hundreds of dimensions. However

K. -W. Lee, W. E. Pickett

The study of the strength of correlations in Na$_x$CoO$_2$ is extended to the x=0 end of the phase diagram where Mott insulating behavior has been widely anticipated. Inclusion of correlation as modeled by the LDA+U approach leads to a Mott transition in the $a_g$ subband if U is no less than U$_c$=2.5 eV. Thus U smaller than U$_c$ is required to model the m

Luis A. F. Almeida, D. Dalmazi

We carry out a numerical and analytic analysis of the Yang-Lee zeros of the 1D Blume-Capel model with periodic boundary conditions and its generalization on Feynman diagrams for which we include sums over all connected and non-connected rings for a given number of spins. In both cases, for a specific range of the parameters, the zeros originally on the unit

Omid Nohadani, Stefan Wessel, Stephan Haas

In disordered spin systems with antiferromagnetic Heisenberg exchange, transitions into and out of a magnetic-field-induced ordered phase pass through a unique regime. Using quantum Monte Carlo simulations to study the zero-temperature behavior, these intermediate regions are determined to be a Bose-Glass phase. The localization of field-induced triplons cau

Sadhan K. Adhikari

Using the axially-symmetric time-dependent Gross-Pitaevskii equation we study the Josephson oscillation of an attractive Bose-Einstein condensate (BEC) in a one-dimensional periodic optical-lattice potential. We find that the Josephson frequency is virtually independent of the number of atoms in the BEC and of the inter-atomic interaction (attractive or repu

Niraj Kumar, Goutam Tripathy

We study front propagation in the reversible reaction-diffusion system A + A <-> A on a 1-d lattice. Extending the idea of leading particle in studying the motion of the front we write a master equation in the stochastically moving frame attached to this particle. This approach provides a systematic way to improve on estimates of front speed obtained earlier

L. Yelash, M. Mueller, W. Paul, K. Binder

The recently developed Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) is investigated for a wide range of model parameters including the parameter m representing the chain length and the thermodynamic temperature T and pressure p. This approach is based upon the first-order thermodynamic perturbation theory for chain molecules developed by We

Roy Ceder, Oded Agam, Zvi Ovadyahu

We analyze current-voltage characteristics taken on Au-doped indium-oxide films. By fitting a scaling function to the data, we extract the electron-phonon scattering rate as function of temperature, which yields a quadratic dependence of the electron-phonon scattering rate on temperature from 1K down to 0.28K. The origin of this enhanced electron-phonon scat

B. Si Lakhal, A. Abada

In the context of the antiferromagnetic spin 1/2 Heisenberg quantum spin chain (XXX model), we estimate the contribution of the exact four-spinon dynamic structure factor $S_4$ by calculating a number of sum rules the total dynamic structure factor $S$ is known to satisfy exactly. These sum rules are: the static susceptibility, the integrated intensity, the

Michael Zaiser, Paolo Moretti

On microscopic and mesoscopic scales, plastic flow of crystals is characterized by large intrinsic fluctuations. Deformation by crystallographic slip occurs in a sequence of intermittent bursts (&#39;slip avalanches&#39;) with power-law size distribution. In the spatial domain, these avalanches produce characteristic deformation patterns in the form of slip

C. K. Duan, A. Mejerink, R. J. Reeves, M. F. Reid

Fluorescence lifetimes of Eu$^{2+}$ doped in CaF$_2$ are measured at various temperatures between 4K and 450K. The lifetime increases with between 100K and 300K, in contrast to the usual lifetime-temperature dependence. At higher or lower temperatures the lifetime decreases with increasing temperature. The phenomenon is explained by simulation of the energy

Chang-Kui Duan, Michael F. Reid, Gang Ruan

The $f\to d$ transition model by Duan and co-workers [Phys. Rev. B {\bf 66}, 155108 (2002); J. Solid State Chem. {\bf 171}, 299 (2003)] has been very useful in interpreting the $f\to d$ absorption, emission and nonradiative relaxation of light lanthanide ions in crystals. However, based on the assumption that the $f^{N-1}$ core spin-orbit interaction is weak

Chang-Kui Duan, Michael F. Reid

The $4f-5d$ transition rates for rare-earth ions in crystals can be calculated with an effective transition operator acting between model $4f^N$ and $4f^{N-1}5d$ states calculated with effective Hamiltonian, such as semi-empirical crystal Hamiltonian. The difference of the effective transition operator from the original transition operator is the corrections

Chang-Kui Duan, Michael F. Reid, Zhongqing Wang

For emitters embedded in media of various refractive indices, different macroscopic or microscopic theoretical models predict different dependencies of the spontaneous emission lifetime on refractive index. Among those models are the two most promising models: the virtual-cavity model and the real-cavity model. It is a priori not clear which model is more re

I. G. Deac, L. Giurgiu, A. Darabont, R. V. Tetean

We present a detailed study of the polycrystalline perovskite manganites La0.67Ca0.33AlxMn1-xO3 (x = 0, 0.1, 0.15, 0.5) at low temperatures and high magnetic fields, including electrical resistance, magnetization, ac susceptibility. The static magnetic susceptibility was also measured up to 1000 K. All the samples show colossal magnetoresistance behavior and

K. Lukierska-Walasek, K. Topolski

We show that p-adic analysis provides a quite natural basis for the description of relaxation in hierarchical glassy systems. For our purposes, we specify the Markov stochastic process considered by S. Albeverio and W. Karwowski. As a result we have obtained a random walk on p-adic integer numbers, which provide the generalization of Cayley tree proposed by

S N Gvasaliya, B Roessli, R A Cowley, P Hubert

The low-energy part of the vibration spectrum in PbMg$_{1/3}$Nb$_{2/3}$O$_3$ (PMN) relaxor ferroelectric has been studied by neutron scattering above and below the Burns temperature, T$_d$. The transverse acoustic and the lowest transverse optic phonons are strongly coupled and we have obtained a model for this coupling. We observe that the lowest optic bran

A. I. Buzdin

The very special characteristic of the proximity effect in superconductor-ferromagnet systems is the damped oscillatory behavior of the Cooper pair wave function in a ferromagnet. In some sense, this is analogous to the inhomogeneous superconductivity, predicted long time ago by Larkin and Ovchinnikov (1964), and Fulde and Ferrell (1964), and constantly sear

M. Csontos, T. Wojtowicz, X. Liu, M. Dobrowolska B. Jankó

Magnetoresistance measurements on the magnetic semiconductor (In,Mn)Sb suggest that magnetic scattering in this material is dominated by isolated Mn$^{2+}$ ions located outside the ferromagnetically-ordered regions when the system is below $T_{c}$. A model is proposed, based on the $p$-$d$ exchange between spin-polarized charge carriers and localized Mn$^{2+

C. Vignat, A. Plastino, A. R. Plastino

Superstatistics is a &#34;statistics&#34; of &#34;canonical-ensemble statistics&#34;. In analogy, we consider here a similar theoretical construct, but based upon the microcanonical ensemble. The mixing parameter is not the temperature but the index q associated with the non-extensive, power law entropy Sq.

Thomas Vilmin, Elie Raphael, Pascal Damman, Sylvain Gabriele

The study of the dewetting of very thin polymer films has recently revealed many unexpected features (e.g. unusual rim morphologies and front velocities) which have been the focus of several theoretical models. Surprisingly, the most striking feature of all, that is a decrease of the rim width with time, have not yet been explained. In the present letter, we

A. Johansson, G. Sambandamurthy, N. Jacobson, D. Shahar

We present the results from an experimental study of the magneto-transport of superconducting wires of amorphous Indium-Oxide, having widths in the range 40 - 120 nm. We find that, below the superconducting transition temperature, the wires exhibit clear, reproducible, oscillations in their resistance as a function of magnetic field. The oscillations are rem

Q. Wang, L. Sheng, C. S. Ting

The current induced local spin polarization due to weak Rashba spin-orbit coupling in narrow strip is studied. In the presence of longitudinal charge current, local spin polarizations appear in the sample. The spin polarization perpendicular to the plane has opposite sign near the two edges. The in-plane spin polarization in the direction perpendicular to th

Sonic H. Y. Chan, T. S. Lo, P. M. Hui, N. F. Johnson

We aim to study the effects of controlling the resource level in agent-based models. We study, both numerical and analytically, a Binary-Agent-Resource (B-A-R) model in which $N$ agents are competing for resources described by a resource level $1/2 \leq {\cal L} < 1$, where ${\cal L} = L/N$ with $L$ being the maximum amount of resource per turn available to

Y. S. Katharria, V. BAranwal, D. C. Agarwal, R. Krishna

The synthesis of embedded silicon carbide was carried out in N type silicon samples having (100) and (111) orientations using high dose implantation of carbon ions at room temperature. The variation of dose was employed to get dose dependence of silicon carbide formation. Postimplant annealing at 1000 C in order to anneal out the implantion induced defects a

Denis Ullmo, Hong Jiang, Weitao Yang, Harold U. Baranger

When treating interactions in quantum dots within a RPA-like approach, time-reversal symmetry plays an important role as higher-order terms -- the Cooper series -- need to be included when this symmetry is present. Here we consider model quantum dots in a magnetic field weak enough to leave the dynamics of the dot chaotic, but strong enough to break time-rev

M. Gheorghe, R. Gutierrez, N. Ranjan, A. Pecchia

We study the influence of structural lattice fluctuations on the elastic electron transport in single-wall carbon nanotubes within a density-functional-based scheme. In the linear response regime, the linear conductance is calculated via configurational averages over the distorted lattice. Results obtained from a frozen-phonon approach as well as from molecu

Gregoire Misguich, Vincent Pasquier, Frederic Mila, Claire Lhuillier

We consider a quantum dimer model (QDM) on the kagome lattice which was introduced recently [Phys. Rev. Lett. 89, 137202 (2002)]. It realizes a Z_2 liquid phase and its spectrum was obtained exactly. It displays a topological degeneracy when the lattice has a non-trivial geometry (cylinder, torus, etc). We discuss and solve two extensions of the model where

R. Gutierrez, S. Mandal, G. Cuniberti

Electronic transport through DNA wires in the presence of a strong dissipative environment is investigated. We show that new bath-induced electronic states are formed within the bandgap. These states show up in the linear conductance spectrum as a temperature dependent background and lead to a crossover from tunneling to thermal activated behavior with incre

Mike Miller, Denis Ullmo, Harold U. Baranger

Despite considerable work on the energy-level and wavefunction statistics of disordered quantum systems, numerical studies of those statistics relevant for electron-electron interactions in mesoscopic systems have been lacking. We plug this gap by using a tight-binding model to study a wide variety of statistics for the two-dimensional, disordered quantum sy

Sergei Bashinsky

We describe analytically the cosmological evolution of primordial gravity waves (tensor perturbations) taking into account their coupling to relic neutrinos. We prove that as a consequence of causality the neutrino-induced phase shift of subhorizon tensor oscillations tends on small scales to zero. For the tensor modes that reenter the horizon in the radiati

Patrick Slane

With Teragauss magnetic fields, surface gravity sufficiently strong to significantly modify light paths, central densities higher than that of a standard nucleus, and rotation periods of only hundredths of a second, young neutron stars are sites of some of the most extreme physical conditions known in the Universe. They generate magnetic winds with particles

D. N. Friedel, Anthony J. Remijan, L. E. Snyder, M. F. A&#39;Hearn

We present interferometric detections of HCN in comets LINEAR (C/2002 T7) and NEAT (C/2001 Q4) with the Berkeley-Illinois-Maryland Association (BIMA) Array. With a 25.4&#34;x20.3&#34; synthesized beam around Comet LINEAR and using a variable temperature and outflow velocity (VTOV) model, we found an HCN column density of N_T=6.4+-2.1x10^12 cm^-2, and a produ

P. Protopapas, J. M. Giammarco, L. Faccioli, M. F. Struble

We present a methodology to discover outliers in catalogs of periodic light-curves. We use cross-correlation as measure of ``similarity&#39;&#39; between two individual light-curves and then classify light-curves with lowest average ``similarity&#39;&#39; as outliers. We performed the analysis on catalogs of variable stars of known type from the MACHO and OG

R. R. Caldwell, Eric V. Linder

We present evidence that the simplest particle-physics scalar-field models of dynamical dark energy can be separated into distinct behaviors based on the acceleration or deceleration of the field as it evolves down its potential towards a zero minimum. We show that these models occupy narrow regions in the phase-plane of w and w&#39;, the dark energy equatio

P. Garcia-Lario, J. V. Perea Calderon

We present a novel classification scheme for stars evolving in the transition phase between the Asymptotic Giant Branch (AGB) to the Planetary Nebula (PN) stage based on the results obtained with ISO-SWS. With the better sensitivity and higher spatial resolution of Spitzer this analysis can now be extended to a larger number of sources located in the Galacti

Sandro Mereghetti

In the last few years it has been recognized that two apparently distinct classes of peculiar high-energy sources are actually related and can be explained as young neutron stars with magnetic fields as high as 10e14 - 10e15 Gauss. One of these &#39;&#39;magnetars&#39;&#39;, SGR 1806-20, has recently emitted the most powerful giant flare ever recorded. The h

Ya. Tikhomirova, B. Stern, A. Kozyreva, J. Poutanen

We performed the scan of the BATSE DISCLA records inspecting 25-50 keV range to pick up soft GRBs. We applied the same technique as in our previous (Stern et al. 2001) scan in the 50-300 keV range. We scanned about 1.8 year of the data and found 30 new gamma-ray burst (GRB)s. The total number of soft GRBs in the BATSE data, with the count rate in the 25-50 k

E. R. Gaynullina, R. W. Schmidt, T. Akhunov, O. Burkhonov

We present the results of a monitoring campaign of the double quasar SBS1520+530 at Maidanak observatory from April 2003 to August 2004. We obtained light curves in V and R filters that show small-amplitude Δm~0.1 mag intrinsic variations of the quasar on time scales of about 100 days. The data set is consistent with the previously determined time delay of Δ

G. J. Madsen, R. J. Reynolds

Halpha and Hbeta spectroscopy with the Wisconsin H-Alpha Mapper (WHAM) reveals a strong concentration of high velocity emission in a ~ 5 by 5 deg area centered near (l.b) = (27,-3), known as the Scutum Cloud. The high velocities imply that we are detecting optical emission from near the plane of the Galaxy out to the tangent point at heliocentric distances o

M. Jura

The dust tails of comets similar to Hale-Bopp can scatter as much optical light as does the Earth. Space-based observatories such as the Terrestrial Planet Finder or Darwin that will detect extra-solar terrestrial planets also will be able to detect extra-solar comets.

Bernardo Lafuerza-Guillen, Jose L. Rodriguez

In this paper we consider probabilistic normed spaces as defined by Alsina, Sklar, and Schweizer, but equipped with non necessarily continuous triangle functions. Such spaces endow a generalized topology that is Fréchet-separable, translation-invariant and countably generated by radial and circled 0-neighborhoods. Conversely, we show that such generalized to

Y. Z. Fan, Bing Zhang, D. M. Wei

We discuss the high enegry afterglow emission (including high energy photons, neutrinos and cosmic rays) following the 2004 December 27 Giant Flare from SGR 1806-20. If the initial outflow is relativistic with a bulk Lorentz factor Γ_0\sim {\rm tens}, the high-energy tail of the synchrotron emission from electrons in the forward shock region gives rise to a

Weiqun Zhang, Andrew I. MacFadyen

We have developed a new computer code, RAM, to solve the conservative equations of special relativistic hydrodynamics (SRHD) using adaptive mesh refinement (AMR) on parallel computers. We have implemented a characteristic-wise, finite difference, weighted essentially non-oscillatory (WENO) scheme using the full characteristic decomposition of the SRHD equati

Vitor Cardoso, Oscar J. C. Dias, Shijun Yoshida

We study scalar field perturbations on the background of non-supersymmetric black rings and of supersymmetric black rings. In the infinite-radius limit of these geometries, we are able to separate the wave equation, and to study wave phenomena in its vicinities. In this limit, we show that (i) both geometries are stable against scalar field perturbations, (i

Amir-Kian Kashani-Poor, Alessandro Tomasiello

Supergravity analysis suggests that the effect of fluxes in string theory compactifications is to gauge isometries of the scalar manifold. However, isometries are generically broken by brane instanton effects. Here we demonstrate how fluxes protect exactly those isometries from quantum corrections which are gauged according to the classical supergravity anal

Olga Mena, Stephen Parke

We explore the physics potential of the NuMI beamline with a detector located 10 km off-axis at a distant site (810 km). We study the sensitivity to $\sin^2 2 θ_{13}$ and to the CP-violating parameter $\sin δ$ as well as the determination of the neutrino mass hierarchy by exploiting the $ν_μ\to ν_e$ and $\barν_μ\to \barν_e$ appearance channels. The results a

A. M. Yakunin, A. Yu. Silov, P. M. Koenraad, J. -M. Tang

The local density of states of Mn-Mn pairs in GaAs is mapped with cross-sectional scanning tunneling microscopy and compared with theoretical calculations based on envelope-function and tight-binding models. These measurements and calculations show that the crosslike shape of the Mn-acceptor wavefunction in GaAs persists even at very short Mn-Mn spatial sepa

Mark D Hannam

I construct initial data for equal-mass irrotational binary black holes using the conformal thin-sandwich puncture (CTSP) approach. I locate quasi-circular orbits using the effective-potential method, and estimate the location of the innermost stable circular orbit (ISCO). The ISCO prediction is consistent with results for conformal thin-sandwich data produc