January 2006 arXiv papers — page 19

Ruggero Maria Santilli

This paper presents nine inconsistency theorems for general relativity theory (GRT), and shows that they ultimately originate from the use of Riemannian curvature and the abandonment of universal invariance (which is stronger than the customary covariance). These features cause GRT to be non-canonical at the classi-cal level and non-unitary at the operator l

Nelson Augusto Alves, Alexandre Souto Martinez

Topological properties of native folds are obtained from statistical analysis of 160 low homology proteins covering the four structural classes. This is done analysing one, two and three-vertex joint distribution of quantities related to the corresponding network of amino acid residues. Emphasis on the amino acid residue hydrophobicity leads to the definitio

GabJin Oh, Cheol-Jun Um, Seunghwan Kim

We investigate statistical properties of daily international market indices of seven countries, and high-frequency $S&P500$ and KOSDAQ data, by using the detrended fluctuation method and the surrogate test. We have found that the returns of international stock market indices of seven countries follow a universal power-law distribution with an exponent of $ζ\

Feng Wu

The physical foundation of the main mathematical concepts in the nonstandard analysis theory of turbulence are presented and discussed. The basic fact is that there does not exist the absolute zero fluid-volume. Therefore, the corresponding physical object to the absolute point is just the uniform fluid-particle. The fluid-particle, in general, corresponds t

Andrey E. Miroshnichenko, Igor Pinkevych, Yuri S. Kivshar

We suggest that tunable orientational nonlinearity of nematic liquid crystals can be employed for all-optical switching in periodic photonic structures with liquid-crystal defects. We consider a one-dimensional periodic structure of Si layers with a local defect created by infiltrating a liquid crystal into a pore, and demonstrate, by solving numerically a s

Nicolas Delerue, Fred Gannaway, David Howell, Grahame Blair

A new laser-wire is being installed in the extraction line of the ATF at KEK. This device aims at demonstrating that laser-wires can be used to measure micrometre scale beam size.

Vadim A. Markel

I have re-calculated the extinction spectra of aggregates of two silver nanospheres shown in Figs.~2 and 3 of Ref.~8. I have used the approximate method of images according to Ref.~8 and an exact numerical technique. I have found that the three sets of data (those I have obtained by the method of images, the numerical results, and the results published in Re

Manuel Cardona, Werner Marx

The availability of a number of databases, in particular the Science Citation Index (SCI), have encouraged the development and use of bibliometric techniques to analyze and evaluate the production and impact of scientists. To avoid pitfalls and their sometimes serious consequences, however, considerable experience with the method is needed. The case of Georg

S. Ahmadi Kandjani, R. Barille, S. Dabos-Seignon, J. -M. Nunzi

Although coherent light is usually required for the self-organization of regular spatial patterns from optical beams, we show that peculiar light matter interaction can break this evidence. In the traditional method to record laser-induced periodic surface structures, a light intensity distribution is produced at the surface of a polymer film by an interfere

J. Rotureau, J. Okolowicz, M. Ploszajczak

We formulate theory of the two-proton radioactivity based on the real-energy continuum shell model. This microscopic approach is applied to describe the two-proton decay of the $1^-_2$ state in $^{18}$Ne.

N. Michel, W. Nazarewicz, M. Ploszajczak, J. Rotureau

The nucleus is a correlated open quantum many-body system. The presence of states that are unbound to particle emission may have significant impact on spectroscopic properties of nuclei, especially those close to the particle drip lines. In the framework of the continuum shell model in the complex momentum-plane, we discuss salient effects of the continuum c

P. J. Borycki, J. Dobaczewski, W. Nazarewicz, M. V. Stoitsov

We discuss methods used in mean-field theories to treat pairing correlations within the local density approximation. Pairing renormalization and regularization procedures are compared in spherical and deformed nuclei. Both prescriptions give fairly similar results, although the theoretical motivation, simplicity, and stability of the regularization procedure

Denis Lacroix, Dominique Durand, Gregory Lehaut, Olivier Lopez

Some prescriptions for in-medium complex particle production in nuclear reactions are proposed. They have been implemented in two models to simulate nucleon-nucleus (nIPSE) and nucleus-nucleus (HIPSE) reactions around the Fermi energy \cite{Lac04,Lac05}. Our work emphasizes the effect of randomness in cluster formation, the importance of the nucleonic Fermi

Jiangyong Jia

PHENIX has measured the two particle azimuth correlation in Au + Au at $\sqrt{s}$ = 200 GeV. Jet shape and yield at the away side are found to be strongly modified at intermediate and low $p_T$, and the modifications vary dramatically with $p_T$ and centrality. At high $p_T$, away side jet peak reappears but the yield is suppressed. We discuss the possible p

Pawan Kumar Netrakanti

The transverse momentum ($p_{\mathrm T}$) spectra for identified charged pions, protons and anti-protons from $p$+$p$ and $d$+Au collisions are measured around midrapidity ($\mid$y$\mid$ $<$ 0.5) over the range of 0.3 $<$ $p_{\mathrm T}$ $<$ 10 GeV/$c$ at $\sqrt{s_{\mathrm {NN}}}$ = 200 GeV. The charged pion and proton+anti-proton spectra at high p_{T} in p+

K. Fuchss, A. Wurm, A. Apte, P. J. Morrison

The breakup of shearless invariant tori with winding number $ω=[0,1,11,1,1,...]$ (in continued fraction representation) of the standard nontwist map is studied numerically using Greene&#39;s residue criterion. Tori of this winding number can assume the shape of meanders (folded-over invariant tori which are not graphs over the x-axis in $(x,y)$ phase space),

Jonathan J Crofts, Ruslan L Davidchack

An algorithm for detecting periodic orbits in chaotic systems [Phys. Rev. E, 60 (1999), pp.~6172--6175], which combines the set of stabilising transformations proposed by Schmelcher and Diakonos [Phys. Rev. Lett., 78 (1997), pp.~4733--4736] with a modified semi-implicit Euler iterative scheme and seeding with periodic orbits of neighbouring periods, has been

Ambedkar Dukkipati, Shalabh Bhatnagar, M Narasimha Murty

The measure-theoretic definition of Kullback-Leibler relative-entropy (KL-entropy) plays a basic role in the definitions of classical information measures. Entropy, mutual information and conditional forms of entropy can be expressed in terms of KL-entropy and hence properties of their measure-theoretic analogs will follow from those of measure-theoretic KL-

Gianluca Panati

In the framework of the theory of an electron in a periodic potential, we reconsider the longstanding problem of the existence of smooth and periodic quasi-Bloch functions, which is shown to be equivalent to the triviality of the Bloch bundle. By exploiting the time-reversal symmetry of the Hamiltonian and some bundle-theoretic methods, we show that the prob

J. Gutierrez, T. Shaska

The purpose of this paper is to study hyperelliptic curves with extra involutions. The locus $Ł_g$ of such genus $g$ hyperelliptic curves is a $g$-dimensional subvariety of the moduli space of hyperelliptic curves $\H_g$. We discover a birational parametrization of $Ł_g$ via dihedral invariants and show how these invariants can be used to determine the field

Paolo Aluffi

We introduce a notion of `proChow group&#39; of varieties, agreeing with the notion of Chow group for complete varieties and covariantly functorial with respect to arbitrary morphisms. We construct a natural transformation from the functor of constructible functions to the proChow functor, extending MacPherson&#39;s natural transformation. We illustrate the

Galin Jones, Murali Haran, Brian Caffo, Ronald Neath

Markov chain Monte Carlo is a method of producing a correlated sample in order to estimate features of a target distribution via ergodic averages. A fundamental question is when should sampling stop? That is, when are the ergodic averages good estimates of the desired quantities? We consider a method that stops the simulation when the width of a confidence i

Wolfgang Ebeling, Sabir M. Gusein-Zade

We discuss different generalizations of the classical notion of the index of a singular point of a vector field to the case of vector fields or 1-forms on singular varieties, describe relations between them and formulae for their computation.

Michael Hochman

Results of Wyner and Ziv and of Ornstein and Weiss show that if one observes the first k outputs of a finite-valued ergodic process, then the waiting time until this block appears again is almost surely asymptotic to $2^{hk}$, where $h$ is the entropy of the process. We examine this phenomenon when the allowed return times are restricted to some subset of ti

Alexander Makin

We consider the Sturm-Liouville operator Lu=u&#39;&#39;-q(x)u with periodic or antiperiodic boundary conditions. It is shown that depending of Fourier coefficients of the potential q(x) the system of root functions may have or may not have the basis property.

G. Barbatis

We provide sufficient conditions under which the difference of the resolvents of two higher-order operators acting in $\R^N$ belongs to trace classes $\cC^p$. We provide explicit estimates on the norm of the resolvent difference in terms of $L^p$ norms of the difference of the coefficients. Such inequalities are useful in estimating the effect of localized p

Petre Birtea, Mircea Puta, Tudor S. Ratiu, Răzvan Micu Tudoran

We investigate the problem of symmetry breaking in the framework of dynamical systems with symmetry on a smooth manifold. Two cases will be analyzed: general and Hamiltonian dynamical systems. We give sufficient conditions for symmetry breaking in both cases.

Alexander Arbieto, Carlos Matheus

We prove that in a compact manifold of dimension $n\geq 2$, a $C^{1+α}$ volume-preserving diffeomorphisms that are robustly transitive in the $C^1$-topology have a dominated splitting. Also we prove that for 3-dimensional compact manifolds, an isolated robustly transitive invariant set for a divergence-free vector field can not have a singularity. In particu

Michael Hochman

We investigate the connection between the abelian rank of a countable amenable group and the existence of good averaging sequences (e.g. for the pointwise ergodic theorem). We show that if $G$ is a group of abelian rank $r(G)$ then any Tempel&#39;man sequence must have constant at least $2^{r(G)}$ and if $G$ is abelian this constant is achieved. On the other

Abdelkader Mokkadem, Mariane Pelletier, Baba Thiam

In this paper we prove large and moderate deviations principles for the recursive kernel estimator of a probability density function and its partial derivatives. Unlike the density estimator, the derivatives estimators exhibit a quadratic behavior not only for the moderate deviations scale but also for the large deviations one. We provide results both for th

Ken-Ichi Yoshikawa

We consider an equivariant analogue of a conjecture of Borcherds. Let $Y$ be a real $K3$ surface without real points. Let $g$ be a Ricci-flat Kaehler metric on $Y$ invariant under the complex conjugation. We shall prove that the equivariant determinant of the Laplacian of $(Y,g)$ with respect to the complex conjugation is expressed as the norm of the Borcher

Ken-Ichi Yoshikawa

We study the singularity of Quillen metrics for one-parameter degenerations of compact Kaehler manifolds.

Ziting Zeng

We present modules for the extended affine Lie algebra $\widetilde{\frak{gl}_{3}(\bc_q)}$ by using the idea of free fields. A necessary and sufficient condition for the modules being unitary is given.

Taeyoung Lee, Melvin Leok, N. Harris McClamroch

An efficient and accurate computational approach is proposed for optimal attitude control of a rigid body. The problem is formulated directly as a discrete time optimization problem using a Lie group variational integrator. Discrete necessary conditions for optimality are derived, and an efficient computational approach is proposed to solve the resulting two

Hitoshi Murakami

This paper has been withdrawn by the author. The author found that the main results here were already obtained by K. Taniyama and A. Yasuhara `On $C$-distance of knots. Kobe J. Math. 11 (1994), no. 1, 117--127. MR1309997 (95j:57010)&#39;. He would like to thank M. Ozawa for the information.

Marina Logares

Let X be a compact Riemann surface together with a finite set of marked points. We use Morse theoretic techniques to compute the Betti numbers of the parabolic U(2,1)-Higgs bundles moduli spaces over X. We give examples for one marked point showing that the Poincare polynomials depend on the system of weights of the parabolic bundle.

Kefeng Liu, Xiaonan Ma

In this note we verify certain statement about the operator $Q\_K$ constructed by Donaldson in [3] by using the full asymptotic expansion of Bergman kernel obtained in [2] and [4].

Tao Mei

Denote by $M_n$ the algebra of $n\times n$ matrices. We consider the dyadic paraproducts $π_b$ associated with $M_n$ valued functions $b$, and show that the $L^\infty (M_n)$ norm of $b$ does not dominate $||π_b||_{L^2(\ell _n^2)\to L^2(\ell_n^2)}$ uniformly over $n$. We also consider paraproducts associated with noncommutative martingales and prove that thei

Raluca Dumitru, Costel Peligrad, Bogdan Visinescu

We obtain some results that relate the Connes spectrum with the innerness of automorphisms in the fixed point local multiplier algebra. The results are variants and/or extensions of corresponding results of Olesen, Pedersen and Stormer [6], [7], [9] and Ara and Mathieu [1] to the case of local multiplier algebras.

James Demmel, Ioana Dumitriu, Olga Holtz

Given a multivariate real (or complex) polynomial $p$ and a domain $\cal D$, we would like to decide whether an algorithm exists to evaluate $p(x)$ accurately for all $x \in {\cal D}$ using rounded real (or complex) arithmetic. Here ``accurately&#39;&#39; means with relative error less than 1, i.e., with some correct leading digits. The answer depends on the

Michael T Lacey

Let $ M_b$ be the operator of pointwise multiplication by $b$, that is $\operatorname M_b f=bf$. Set $[ A,B]={} AB- BA$. The Reisz potentials are the operators $$ R_αf(x)=\int f(x-y)\frac{dy}{\abs y ^α},\qquad 0<α<1. $$ They map $L^p\mapsto L^q$, for $1-α+\frac1q=\frac1p$, a fact we shall take for granted in this paper. A Theorem of Chanillo \cite{MR84j:4202

Leonardo Biliotti

We obtain the full classification of coisotropic and polar actions of compact Lie group on irreducible Hermitian symmetric spaces.

Leonardo Biliotti

We prove the Focal Index Lemma and the Rauch and Berger comparison theorems on a weak Riemannian Hilbert manifold with a smooth Levi-Civita connection and we apply these results to the free loop spaces of a compact manifold with the L^2 metrics

A. Gorsky, M. Shifman, A. Yung

We address two distinct but related issues: (i) the impact of (two-dimensional) axions in a two-dimensional theory known to model confinement, the CP(N-1) model; (ii) bulk axions in four-dimensional Yang-Mills theory supporting non-Abelian strings. In the first case n, \bar n kinks play the role of &#34;quarks.&#34; They are known to be confined. We show tha

Riccardo Apreda, Johanna Erdmenger, Nick Evans, Johannes Grosse

Recent work on adding flavour to the generalized AdS/CFT correspondence is reviewed. In particular, we consider instanton configurations on two coincident D7 brane probes. These are matched to the Higgs branch of the dual field theory. In AdS_5 x S^5, the instanton generates a flow of the meson spectrum. For non-supersymmetric gravity backgrounds, the Higgs

Johannes Aastrup, Jesper M. Grimstrup

An intersection of Noncommutative Geometry and Loop Quantum Gravity is proposed. Alain Connes&#39; Noncommutative Geometry provides a framework in which the Standard Model of particle physics coupled to general relativity is formulated as a unified, gravitational theory. However, to this day no quantization procedure compatible with this framework is known.

A. A. Slavnov

A renormalizable model of electroweak interaction which coincides with Weinberg-Salam model in the gauge boson - fermion sector but does not require the existence of fundamental scalar fields is proposed.

Burkhard Kleihaus, Jutta Kunz, Kari Myklevoll

We construct globally regular gravitating solutions, which possess only discrete symmetries. These solutions of Yang-Mills-dilaton theory may be viewed as exact (numerical) solutions of scalar gravity, by considering the dilaton as a kind of scalar graviton, or as approximate solutions of Einstein-Yang-Mills theory. We focus on platonic solutions with cubic

Z. Haba

We consider quantum theory of fields ϕdefined on a D dimensional manifold (bulk) with an interaction V(ϕ) concentrated on a d<D dimensional surface (brane). Such a quantum field theory can be less singular than the one in d dimensions with the interaction $V(ϕ)$. It is shown that scaling properties of fields on the brane are different from the ones in the bu

H. Kohyama, A. Niegawa

Within the framework of Tsallis statistics with q ~ 1, we construct a perturbation theory for treating relativistic quantum field systems. We find that there appear initial correlations, which do not exist in the Boltzmann-Gibbs statistics. Applying this framework to a quark-gluon plasma, we find that the so-called thermal masses of quarks and gluons are sma

Dirk Roder

After a brief introduction on QCD and effective models in the first chapter, I analyze the dependence of the QCD transition temperature on the quark (or pion) mass in the second chapter. I found that a linear sigma model, which links the transition to chiral symmetry restoration, predicts a much stronger dependence of T_c on m_pi than seen in present lattice

A. Gehrmann-De Ridder, T. Gehrmann, E. W. N. Glover

We describe the antenna subtraction method for treating real emission singularities in the calculation of jet observables at NNLO accuracy, in particular in view of the computation $e^+e^- \to 3$ jets at NNLO.

Claudio Dib, Amand Faessler, Thomas Gutsche, Sergey Kovalenko

We calculate the electric dipole form factor of the neutron in a perturbative chiral quark model, parameterizing CP-violation of generic origin by means of effective electric dipole moments of the constituent quarks and their CP-violating couplings to the chiral fields. We discuss the relation of these effective parameters to more fundamental ones such as th

J. Vijande, F. Fernandez, A. Valcarce

We present a theoretical framework that accounts for the new $D_J$ and $D_{sJ}$ mesons measured in the open-charm sector. These resonances are properly described if considered as a mixture of conventional $P-$wave quark-antiquark states and four-quark components. The narrowest states are basically $P-$wave quark-antiquark mesons, while the dominantly four-qu

Emanuele Berti, Vitor Cardoso, Clifford M. Will

We provide some considerations on the excitation of black hole quasinormal modes (QNMs) in different physical scenarios. Considering a simple model in which a stream of particles accretes onto a black hole, we show that resonant QNM excitation by hyperaccretion requires a significant amount of fine-tuning, and is quite unlikely to occur in nature. Then we su

Soumya D. Mohanty, Malik Rakhmanov, Sergei Klimenko, Guenakh Mitselmakher

The detection and estimation of gravitational wave burst signals, with {\em a priori} unknown polarization waveforms, requires the use of data from a network of detectors. For determining how the data from such a network should be combined, approaches based on the maximum likelihood principle have proven to be useful. The most straightforward among these use

G. L. Comandi, M. L. Chiofalo, R. Toncelli, D. Bramanti

Recent theoretical work suggests that violation of the Equivalence Principle might be revealed in a measurement of the fractional differential acceleration $η$ between two test bodies -of different composition, falling in the gravitational field of a source mass- if the measurement is made to the level of $η\simeq 10^{-13}$ or better. This being within the r

Yuri N. Obukhov

We describe plane-fronted waves in the Yang-Mills type quadratic metric-affine theory of gravity. The torsion and the nonmetricity are both nontrivial, and they do not belong to the triplet ansatz.

Gordon McCabe

The purpose of this paper is to discuss the various types of physical universe which could exist according to modern mathematical physics. The paper begins with an introduction that approaches the question from the viewpoint of ontic structural realism. Section 2 takes the case of the &#39;multiverse&#39; of spatially homogeneous universes, and analyses the

Jing Jiang, Krishna R. Narayanan

We consider coding schemes for channels with non-uniform inputs (NUI), where standard linear block codes can not be applied directly. We show that multilevel coding (MLC) with a set of linear codes and a deterministic mapper can achieve the information rate of the channel with NUI. The mapper, however, does not have to be one-to-one. As an application of the

Shai Carmi, Reuven Cohen, Danny Dolev

We suggest a method for routing when the source does not posses full information about the shortest path to the destination. The method is particularly useful for scale-free networks, and exploits its unique characteristics. By assigning new (short) names to nodes (aka labelling) we are able to reduce significantly the memory requirement at the routers, yet

Andrej Brodnik, Johan Karlsson, J. Ian Munro, Andreas Nilsson

In this paper we study the Prefix Sum problem introduced by Fredman. We show that it is possible to perform both update and retrieval in O(1) time simultaneously under a memory model in which individual bits may be shared by several words. We also show that two variants (generalizations) of the problem can be solved optimally in $Θ(\lg N)$ time under the com

Ambedkar Dukkipati, M Narasimha Murty, Shalabh Bhatnagar

Though Shannon entropy of a probability measure $P$, defined as $- \int_{X} \frac{\ud P}{\ud μ} \ln \frac{\ud P}{\udμ} \ud μ$ on a measure space $(X, \mathfrak{M},μ)$, does not qualify itself as an information measure (it is not a natural extension of the discrete case), maximum entropy (ME) prescriptions in the measure-theoretic case are consistent with tha

Katherine Luo, Yifan Li, Charis Ermopoulos, William Yurcik

In the UNIX/Linux environment the kernel can log every command process created by every user using process accounting. This data has many potential uses, including the investigation of security incidents. However, process accounting data is also sensitive since it contains private user information. Consequently, security system administrators have been hinde

Riccardo Pucella

The framework of algorithmic knowledge assumes that agents use algorithms to compute the facts they explicitly know. In many cases of interest, a deductive system, rather than a particular algorithm, captures the formal reasoning used by the agents to compute what they explicitly know. We introduce a logic for reasoning about both implicit and explicit knowl

Ashfia Huq, Peter W. Stephens

We show that Rb_4C_60 transforms from its ambient pressure orientationally disordered tetragonal structure to an ordered orthorhombic structure (isostructural to Cs_4C_60) at or above 0.4 GPa. This opens the possibility of studying the previously observed metal-insulator transition under pressure in this narrow band system as a function of a continuous varia

M. Georgiev, M. Borissov

The vibronic mixing by an odd-parity vibrational mode of two opposite-parity nearly-degenerate electronic states at a molecular site may drive the small polaron off-center. An associated electric dipole may occur due to broken inversion symmetry which will exert an effect on the electric, optical and transport properties of the host crystal. We first investi

H. B. de Carvalho, M. J. S. P. Brasil, V. Lopez-Richard, I. Camps

We report experimental evidence of excitonic spin-splitting, in addition to the conventional Zeeman effect, produced by a combination of the Rashba spin-orbit interaction, Stark shift and charge screening. The electric-field-induced modulation of the spin-splitting are studied during the charging and discharging processes of p-type GaAs/AlAs double barrier r

A. Carbone, B. K. Kotowska, D. Kotowski

The $f^{-γ}$ sloped current noise power spectra, observed in organic semiconductors, have been interpreted within a {\em variable range hopping} mechanism of the fluctuations. The relative current noise power spectral density ${\cal S}(f)=S_I(f)/I^2$ exhibits a maximum at the {\em trap-filling transition} between the {\em ohmic} and the {\em space-charge-lim

Carlo Pierleoni, Chris Addison, Jean-Pierre Hansen, Vincent Krakoviack

Starting from a microscopic lattice model, we investigate clustering, micellization and micelle ordering in semi-dilute solutions of AB diblock copolymers in a selective solvent. To bridge the gap in length scales, from monomers to ordered micellar structures, we implement a two-step coarse graining strategy, whereby the AB copolymers are mapped onto ``ultra

Ronald Dickman

I report large-scale Monte Carlo studies of a one-dimensional height-restricted stochastic sandpile using the quasistationary simulation method. Results for systems of up to 50 000 sites yield estimates for critical exponents that differ significantly from those obtained using smaller systems, but are consistent with recent predictions derived from a Langevi

R. J. W. Stas, J. M. McNamara, W. Hogervorst, W. Vassen

We present a theoretical and experimental investigation of homonuclear ionizing collisions of laser-cooled metastable helium atoms, considering both the fermionic He-3 and bosonic He-4 isotope. The theoretical description combines quantum threshold behavior, Wigner&#39;s spin-conservation rule and quantum statistical symmetry requirements in a single-channel

Victor Barzykin, Lev P. Gor&#39;kov

We consider competition of Kondo effect and s-wave superconductivity in heavy fermion and mixed valence superconductors, using the phenomenological approach for the periodic Anderson model. Similar to the well known results for single-impurity Kondo effect in superconductors, we have found principal possibility of a re-entrant regime of the superconducting t

K. A. Al-Hassanieh, A. E. Feiguin, J. A. Riera, C. A. Busser

A procedure based on the recently developed ``adaptive&#39;&#39; time-dependent density-matrix-renormalization-group (DMRG) technique is presented to calculate the zero temperature conductance of nanostructures, such as a quantum dots (QD&#39;s) or molecular conductors, when represented by a small number of active levels. The leads are modeled using non-inte

Emilia Witkowska, Mariusz Gajda, Jan Mostowski

We investigate a real scalar field whose dynamics is governed by a nonlinear wave equation. We show that classical description can be applied to a quantum system of many interacting bosons provided that some quantum ingredients are included. An universal action has to be introduced in order to define particle number. The value of this action should be equal

Y. Krivolapov, A. Mann, Joseph L. Birman

A new investigation of the coexistence and competition of ferroelectricity and superconductivity is reported. In particular we show that the starting Hamiltonian of a previous study by Birman and Weger (2001) can be exactly diagonalized. The result differs significantly from mean-field theory. A Hamiltonian with a different realization of the coupling betwee

J. de la Figuera, N. C. Bartelt, K. F. McCarty

The density of two-dimensional Ag adatom gases on W(110) is determined by monitoring local electron reflectivity using low energy electron microscopy (LEEM). This method of adatom concentration measurement can detect changes in adatom density at least as small as 10$^{-3}$ ML for a $μ$m size region of the surface. Using this technique at high temperatures, w

M. E. Zhitomirsky

Magnetic excitations are studied in gapped quantum spin systems, for which spontaneous two-magnon decays are allowed by symmetry. Interaction between one- and two-particle states acquires nonanalytic frequency and momentum dependence near the boundary of two-magnon continuum. This leads to a termination point of single-particle branch for one-dimensional sys

Martino De Prato, Andrea Pelissetto, Ettore Vicari

We study the nature of the two-dimensional quantum critical point separating two phases with and without long-range spin-density-wave order, which has been recently observed in cuprate superconductors. We consider the Landau-Ginzburg-Wilson Hamiltonian associated with the spin-density critical modes, perform a mean-field analysis of the phase diagram, and st

M. R. Bakhtiari, P. Vignolo, M. P. Tosi

Growing interest is being given to transport of ultra-cold atomic gases through optical lattices generated by the interference of laser beams. In this connection we evaluate the phase-coherent transport of a spin-polarized gas of fermionic atoms along linear structures made from potential wells set in four alternative types of sequence. These are periodic ch

Thomas Bickel

The dynamics of a tracer molecule near a fluid membrane is investigated, with particular emphasis given to the interplay between the instantaneous position of the particle and membrane fluctuations. It is found that hydrodynamic interactions creates memory effects in the diffusion process. The random motion of the particle is then shown to cross over from a

Daniel Gandolfo, Lahoussine Laanait, Salvador Miracle-Solé, Jean Ruiz

Within a semi--infinite thre--dimensional lattice gas model describing the coexistence of two phases on a substrate, we study, by cluster expansion techniques, the free energy (line tension) associated with the contact line between the two phases and the substrate. We show that this line tension, is given at low temperature by a convergent series whose leadi

Jin-Wu Jiang, Hui Tang, Bing-Shen Wang, Zhao-Bin Su

In this paper, we provide a detailed expression of the vibrational potential for the lattice dynamics of the single-wall carbon nanotubes (SWCNT) satisfying the requirements of the exact rigid translational as well as rotational symmetries, which is a nontrivial generalization of the valence force model for the planar graphene sheet. With the model, the low

P. Voll, N. apRoberts-Warren, R. J. Zieve

We examine the stability of a pinned superfluid helium vortex line by measuring its persistence at elevated temperatures. Each vortex terminates at the surface of the container, at either a rounded bump or a conical indentation. We find that pinning with the bump termination is much easier to overcome thermally. This behavior would not be expected from consi

Mihail Vladkov, J. -L. Barrat

Using molecular dynamics simulations, we determine the linear and nonlinear viscoelastic properties of a model polymer melt in the unentangled regime. Several approaches are compared for the computation of linear moduli, including Green-Kubo and non equilibrium molecular dynamics (NEMD). An alternative approach, based on the use of the Rouse modes, is also d

K. Malarz

Topology of exponential and scale-free trees and simple graphs is investigated numerically. The numbers of the nearest neighbors, the next-nearest neighbors, the next-next-nearest neighbors, the 4-th and the 5-th neighbors are calculated. The functional dependence of the node-to-node distance d_{ij} on the product of connectivities k_ik_j has been also check

J. E. Prieto, E. Korutcheva, I. Markov

Quantum dots have promising properties for optoelectronic applications. They can be grown free of dislocations in highly mismatched epitaxy in the coherent Stranski-Krastanov mode. In this chapter, some thermodynamic aspects related to the wetting in the growth and self-assembly of three-dimensional (3D) coherent islands are studied using an energy minimizat

Dawn M. Gelino, Solen Balman, Umit Kizilouglu, Arda Yilmaz

We have obtained optical and infrared photometry of the quiescent soft X-ray transient XTE J1118+480. In addition to optical and J-band variations, we present the first observed H- and K_s-band ellipsoidal variations for this system. We model the variations in all bands simultaneously with the WD98 light curve modeling code. The infrared colors of the second

Casey Papovich, GOODS, MIPS GTO teams

I discuss constraints on star--formation and AGN activity in massive galaxies at z~1-3 using observations from the Spitzer Space Telescope. In particular I focus on a sample of distant red galaxies (DRGs) with J-K>2.3 in GOODS-S. Based on their ACS, ISAAC, and IRAC photometry, the DRGs have typical stellar masses >10^11 Msol. Interestingly, the majority (>50

Jeremy D. Schnittman

This Thesis describes the basic framework and applications of a relativistic ray-tracing code for analyzing accretion processes around Kerr black holes. We begin in Chapter 1 with a brief historical summary of the major advances in black hole astrophysics over the past few decades. In Chapter 2 we present a detailed description of the ray-tracing code, which

Konstantin V. Getman, Eric D. Feigelson, Leisa Townsley, Patrick Broos

Cepheus B (Cep B) molecular cloud and a portion of the nearby Cep OB3b OB association, one of the most active regions of star formation within 1 kpc, has been observed with the ACIS detector on board the Chandra X-ray Observatory. We detect 431 X-ray sources, of which 89% are confidently identified as clustered pre-main sequence stars. Two main results are o

Inger Jorgensen, Kristin Chiboucas, Kathleen Flint, Marcel Bergmann

We present the Fundamental Plane (FP) for 38 early-type galaxies in the two rich galaxy clusters RXJ0152.7-1357 (z=0.83) and RXJ1226.9+3332 (z=0.89), reaching a limiting magnitude of M_B =-19.8 mag in the rest frame of the clusters. While the zero point offset of the FP for these high redshift clusters relative to our low redshift sample is consistent with p

Marcelo Gleiser, Joel Thorarinson

The development of prebiotic homochirality on early-Earth or another planetary platform may be viewed as a critical phenomenon. It is shown, in the context of spatio-temporal polymerization reaction networks, that environmental effects -- be them temperature surges or other external disruptions -- may destroy any net chirality previously produced. In order t

Karen T. Lewis Michael Eracleous

We have obtained near-IR spectra of five Active Galactic Nuclei that exhibit double-peaked Balmer Emission Lines (NGC 1097, Pictor A, PKS 0921-213, 1E 0450.30-1817, and IRAS 0236.6-3101). The stellar velocity dispersions of the host galaxies were measured from the Ca II 8494,8542,8662 Angstrom absorption lines and were found to range from 140 to 200 km/s. Us

AMANDA Collaboration, M. Ackermann

The Antarctic Muon And Neutrino Detector Array (Amanda) is a high-energy neutrino telescope. It is a lattice of optical modules (OM) installed in the clear ice below the South Pole Station. Each OM contains a photomultiplier tube (PMT) that detects photons of Cherenkov light generated in the ice by muons and electrons. IceCube is a cubic-kilometer-sized expa

E. Fernandez Lajus, V. S. Niemela;

ASAS photometric observations of LS 1135, an O-type SB1 binary system with an orbital period of 2.7 days, show that the system is also eclipsing. This prompted us to re-examine the spectra used in the previously published spectroscopic orbit. Our new analysis of the spectra obtained near quadratures, reveal the presence of faint lines of the secondary compon

R. E. Mennickent, W. Gieren, I. Soszynski, G. Pietrzynski

We have performed a search for variable stars in the dwarf irregular galaxy NGC 6822 using wide-field multi-epoch VI photometry down to a limiting magnitude $V$ $\sim$ 22. Apart from the Cepheid variables in this galaxy already reported in an earlier paper by Pietrzynski et al. (2004), we have found 1019 &#34;non-periodic&#34; variable stars, 50 periodically

Gaspar Galaz, Alvaro Villalobos, Leopoldo Infante, Carlos Donzelli

It is an observational fact that bulges of spiral galaxies contain a high fraction of old and metal-rich stars. Following this observational fact, we have investigated colors of 21 bulges hosted by a selected sample of high surface brightness spirals and low surface brightness galaxies observed in B and R optical bands and in J and Ks near-IR bands. Using st

John Kormendy, Mark E. Cornell, David L. Block, Johan H. Knapen

We present Ks-band surface photometry of NGC 7690 (Hubble type Sab) and NGC 4593 (SBb). We find that, in both galaxies, a major part of the &#34;bulge&#34; is as flat as the disk and has approximately the same color as the inner disk. In other words, the &#34;bulges&#34; of these galaxies have disk-like properties. We conclude that these are examples of &#34

James Etherington, Witold Maciejewski

If supermassive black holes in centres of galaxies form by merging of black-hole remnants of massive Population III stars, then there should be a few black holes of mass one or two orders of magnitude smaller than that of the central ones, orbiting around the centre of a typical galaxy. These black holes constitute a weak perturbation in the gravitational po