February 2002 arXiv papers — page 24

Ian Hayes, Robert Colvin, David Hemer, Paul Strooper

Existing refinement calculi provide frameworks for the stepwise development of imperative programs from specifications. This paper presents a refinement calculus for deriving logic programs. The calculus contains a wide-spectrum logic programming language, including executable constructs such as sequential conjunction, disjunction, and existential quantifica

Harry Buhrman, Alessandro Panconesi, Riccardo Silvestri, Paul Vitanyi

We show that Naming-- the existence of distinct IDs known to all-- is a hidden but necessary assumption of Herlihy's universality result for Consensus. We then show in a very precise sense that Naming is harder than Consensus and bring to the surface some important differences existing between popular shared memory models.

Johnpierre Paglione, C. Lupien, W. A. MacFarlane, J. M. Perz

The six independent elastic constants of Sr$_2$RuO$_4$ were determined using resonant ultrasound spectroscopy on a high-quality single-crystal specimen. The constants are in excellent agreement with those obtained from pulse-echo experiments performed on a sample cut from the same ingot. A calculation of the Debye temperature using the measured constants agr

Valery N. Marachevsky

A new formula for the Casimir energy of a dispersive dilute dielectric ball is discussed. The formula for the Casimir energy of a polarizable particle situated in a perfectly conducting wedge-shaped cavity is derived by a path-integral coordinate space method in quantum field theory.

S. Cruz-Barrios, M. C. Nemes, A. F. R. de Toledo Piza

Entanglement of spin and position variables produced by spatially inhomogeneous magnetic fields of Stern-Gerlach type acting on spinor Bose-Einstein condensates may lead to interference effects at the level of one-boson densities. A model is worked out for these effects which is amenable to analytical calculation for gaussian shaped condensates. The resultin

Joachim Krug, Christian Karl

Biological evolution in a sequence space with random fitnesses is studied within Eigen's quasispecies model. A strong selection limit is employed, in which the population resides at a single sequence at all times. Evolutionary trajectories start at a randomly chosen sequence and proceed to the global fitness maximum through a small number of intermittent

M. Cristiani, O. Morsch, J. H. Müller, D. Ciampini

We report experimental results on the properties of Bose-Einstein condensates in 1D optical lattices. By accelerating the lattice, we observed Bloch oscillations of the condensate in the lowest band, as well as Landau-Zener (L-Z) tunneling into higher bands when the lattice depth was reduced and/or the acceleration of the lattice was increased. The dependenc

Emmanuel Sunyer, Philippe Jund, Remi Jullien

We study the structural and dynamical characteristics of the sodium atoms inside and outside the ``diffusion channels'' in glassy Na$_2$O-4SiO$_2$ (NS4) using classical molecular dynamics. We show that on average neither energetic arguments nor local environment considerations can explain the increased density of sodium atoms inside the subspace made

O. Betbeder-Matibet, M. Combescot

Pauli exclusion between the carriers of $N$ excitons induces novel many-body effects, quite different from the ones generated by Coulomb interaction. Using our commutation technique for interacting close-to-boson particles, we here calculate the hamiltonian expectation value in the $N$-ground-state-exciton state.Coulomb interaction enters this quantity at fi

C. Proust, A. Audouard, L. Brossard, S. Pesotskii

Interlayer magnetoconductance of the quasi-two dimensional organic metal (BEDT-TTF)8Hg4Cl12(C6H5Cl)2 has been investigated in pulsed magnetic fields extending up to 36 T and in the temperature range from 1.6 to 15 K. A complex oscillatory spectrum, built on linear combinations of three basic frequencies only is observed. These basic frequencies arise from th

Matt Hall, Kim Christensen, Simone A. di Collobiano, Henrik Jeldtoft Jensen

We present an individual based model of evolutionary ecology. The reproduction rate of individuals characterized by their genome depends on the composition of the population in genotype space. Ecological features such as the taxonomy and the macro-evolutionary mode of the dynamics are emergent properties. The macro-dynamics exhibit intermittent two mode swit

P. Schmidt, H. Monien

We present a generalized dynamical mean-field approach for the nonequilibrium physics of a strongly correlated system in the presence of a time-dependent external field. The Keldysh Green's function formalism is used to study the nonequilibrium problem. We derive a closed set of self-consistency equations in the case of a driving field with frequency Ome

Yoseph Imry

This note has no new results and is therefore not intended to be submitted to a "research" journal in the foreseeable future, but to be available to the numerous individuals who are interested in this issue. Several of those have approached the author for his opinion, which is summarized here in a hopefully pedagogical manner, for convenience. It is

Jozef Spalek, Pawel Wrobel

We characterize the coexistence of itinerant ferromagnetism and spin-triplet superconductivity within a single mechanism involving local (Hund's rule) exchange among $d$ electrons. The ratio of transition temperatures and the spin anisotropy of the superconducting gap is estimated for $ZrZn_2$. The $A$ phase is stable in very low applied and molecular fi

George Kastrinakis

We make the case for an electronic origin of the strong mode, recently seen in ARPES experiments, and, in this regard, further discuss the physics of the spin resonance peak.

G. Iovane

MEDEA Program (Microlensing Experiment Data-Analysis Software for Event with Amplification) is here presented. It is developed to the pixel lensing analysis used by SLOTT-AGAPE (Systematic Lensing Observation at Toppo Telescope - Andromeda Gravitational Amplification Pixel Experiment) Collaboration. All software components are fully automated and they can be

B. B. Jones

Part I describes the analysis of periodic and transient signals in EGRET data. A method to search for the transient flux from gamma-ray bursts independent of triggers from other gamma-ray instruments is developed. Several known gamma-ray bursts were independently detected, and there is evidence for a previously unknown gamma-ray burst candidate. Statistical

Catherine E. Grant, Mark W. Bautz, Shanil N. Virani

It was observed early on in the Chandra X-ray Observatory mission that the background rates of the Advanced CCD Imaging Spectrometer (ACIS) were highly variable on both short and long timescales. We present analysis of lightcurves of the high energy (> 15 keV) ACIS background spanning most of the mission lifetime. These high energy events are not produced by

D. Leisawitz, T. Armstrong, D. Benford, A. Blain

The question "How did we get here and what will the future bring?" captures the human imagination and the attention of the National Academy of Science's Astronomy and Astrophysics Survey Commitee (AASC). Fulfillment of this "fundamental goal" requires astronomers to have sensitive, high angular and spectral resolution observations in the

Ranga-Ram Chary

I discuss the possibility of differentiating between popular models for gamma-ray bursts by using multiwavelength observations to constrain the characteristics of their host galaxies, in particular the age of the stellar populations.

Niayesh Afshordi

If there was a weak magnetic field in the early universe, cyclotron emission could play an important role in the thermalization of the CMB. We study this process in the tightly coupled primordial electron-photon plasma and find that if the magnetic field is large enough so that the plasma effects allow emission of cyclotron photons, this process will wipe ou

Paul J. Green, Chris Kochanek, Aneta Siemiginowska, Dong-Woo Kim

The components of the wide (7.3") separation quasar pair Q2345+007A,B (z=2.15) have the most strikingly similar optical spectra seen to date (Steidel & Sargent 1991) yet no detected lensing mass, making this system the best candidate known for a massive (1e14 Msun) dark matter lens system. Here we present results from a 65ksec Chandra observation designe

A. Comastri, M. Mignoli, P. Ciliegi, P. Severgnini

Recent X-ray surveys have clearly demonstrated that a population of optically dull, X-ray bright galaxies is emerging at 2-10 keV fluxes of the order of 10^{-14} erg cm^{-2} s^{-1}. Although they might constitute an important fraction of the sources responsible for the hard X-ray background, their nature is still unknown. With the aim to better understand th

E. Piconcelli, L. Bassani, M. Cappi, F. Fiore

We present preliminary results from a XMM-Newton spectroscopic survey of hard (2 -10 keV) X-ray sources detected serendipitously in seven EPIC FOVs. All observations were performed during the performance/verif ication phase. The resulting sample consists of 39 sources with fluxes ranging from 3 to 80 $\t imes$ 10$^{-14}$ erg cm$^{-2}$ s$^{-1}$ in the 2-10 ke

L. Sidoli, A. N. Parmar, T. Oosterbroek, D. Lumb

We report the detection of a complex of narrow X-ray absorption features from the low-mass X-ray binary GX13+1 during 3 XMM-Newton observations in 2000 March and April. The features are consistent with being due to resonant scattering of the K_alpha and K_beta lines of He- and H-like iron (Fe xxv and Fe xxvi) and H-like calcium (Ca xx) K_alpha. Only the Fe x

Christian Hettlage, Karl Mannheim

After briefly reviewing various hadronic neutrino source models, we show how to construct generic upper flux bounds. We then turn to the problem of neutrino propagation through the inner Earth and neutrino detection in water-based Cerenkov detectors. Applying the formalism thus developed to the Mannheim-Protheroe-Rachen and the Waxman&Bahcall flux bounds, we

C. Brocksopp, M. F. Bode, S. P. S. Eyres, M. M. Crocker

We present HST/WFPC2 images of the symbiotic star V1016 Cyg which, for the first time, directly explore the inner regions of the nebula to AU scales at optical wavelengths. They also suggest that the [OIII] 4959,5007 emission takes place in a bipolar outflow. We use these images to determine the position of the two stars and hence a projected binary separati

HEGRA Collaboration, F. Aharonian

The detection of TeV gamma-rays from the blazar H 1426+428 at an integral flux level of (4 +- 2(stat) +- 1(syst)) 10^(-12) erg cm^(-2) s^(-1) above 1 TeV with the HEGRA imaging atmospheric Cherenkov telescope system is reported. H 1426+428 is located at a redshift of z=0.129, which makes it the most distant source detected in TeV gamma-rays so far. The TeV r

C. Badenes, E. Bravo

Supernova remnants are usually analysed in the light of hydrodynamical models of the interaction of supernova ejecta with either a constant density ambient medium or a circumstellar medium produced by a constant presupernova wind. However, the ejection of energetic wind during the presupernova phase changes the ambient medium structure and, consequently, the

A. -C. Donea, R. J. Protheroe

The radiation fields external to the jets and originating from within a few parsecs from the black hole, are discussed in this paper. They are the direct radiation from an accretion disk in symbiosis with jets, the radiation field from the broad line region (BLR) surrounding the accretion disk, and the infrared radiation from a dusty torus. The jet/disk symb

Falk Herwig, Norbert Langer, Maria Lugaro

We discuss the occurrence of the s-process during the radiative interpulse phase of rotating AGB stars. Due to differential rotation, protons are mixed into C12-rich layers after thermal pulses, in the course of the so called third dredge up episode. We follow the time evolution of key isotope abundances in the relevant layers with a post-processing code whi

Daniel J. H. Chung, Katherine Freese

We consider a scenario in which our observable universe is a 3-dimensional surface (3-brane) living in extra dimensions with a warped geometry. We show that ``lensed'' density perturbations from other branes serve as possible seeds for structure formation on our observable brane (without inflation), and, in addition, provide constraints on braneworld

A. K. H. Kong, M. R. Garcia, F. A. Primini, R. Di Stefano

We have been monitoring M31 with HRC and ACIS onboard \chandra regularly in the past two years. By combining eight \chandra ACIS-I observations taken between 1999 to 2001, we have identified 204 X-ray sources within the central $\sim 17\arcmin\times17\arcmin$ region of M31, with a detection limit of $\sim 1.6\times10^{35}$\lum. Of these 204 sources, 21 are i

J. Kennea, F. Cordova, S. Chatterjee, J. Cordes

The pulsar PSR J0631+1036 was discovered during a radio search of Einstein X-ray source error circles. A detection of a 288ms sinusoidal modulation in the ASCA lightcurve, the same period as the radio pulsar, appeared to confirm the association of the X-ray source and the pulsar. Its X-ray spectrum was said to be similar to that of middle aged gamma-ray puls

Jacques Moret-Bailly

The Impulsive Stimulated Raman Scattering (ISRS) is a parametric light-matter interaction which shifts the frequencies of two ultrashort laser light pulses by a non-quantified transfer of energy. As ISRS has no threshold, the laser pulses may be replaced by the pulses which constitute the ordinary incoherent light. This replacement has the expected qualitati

Todd Tilma, Mark S. Byrd, E. C. G. Sudarshan

In this paper we give an explicit parametrization for all two qubit density matrices. This is important for calculations involving entanglement and many other types of quantum information processing. To accomplish this we present a generalized Euler angle parametrization for SU(4) and all possible two qubit density matrices. The important group-theoretical p

Arundhati Dasgupta

We discuss Wick rotations in the context of gravity, with emphasis on a non-perturbative Wick rotation proposed in hep-th/0103186 mapping real Lorentzian metrics to real Euclidean metrics in proper-time coordinates. As an application, we demonstrate how this Wick rotation leads to a correct answer for a two dimensional non-perturbative path-integral.

Yogesh N. Joglekar, Allan H. MacDonald

Bilayer quantum Hall system at total filling factor $ν=1$ shows a rich variety of broken symmetry ground states because of the competition between the interlayer and intralayer Coulomb interactions. When the layers are sufficiently close, a bilayer system develops spontaneous interlayer phase-coherence that manifests itself through a spectacular enhancement

Matthew Benacquista

The galactic population of globular clusters are old, dense star systems, with a typical cluster containing $10^4 - 10^6$ stars. As an old population of stars, globular clusters contain many collapsed and degenerate objects. As a dense population of stars, globular clusters are the scene of many interesting close dynamical interactions between stars. These d

A. I. Shoshi, F. D. Steffen, H. J. Pirner

A model combining perturbative and non-perturbative QCD is developed to compute high-energy reactions of hadrons and photons and to investigate saturation effects that manifest the S-matrix unitarity. Following a functional integral approach, the S-matrix factorizes into light-cone wave functions and the universal amplitude for the scattering of two color-di

Eugen Paal

The deformation equation and its integrability condition (Bianchi identity) of a non-(co)associative deformation in operad algebra are found. Based on physical analogies, cogravity equations are proposed.

Aeree Chung, J. H. van Gorkom, K. O'Neil, G. D. Bothun

We present VLA HI imaging of four LSB galaxies which were thought to strongly deviate from the TF relation based on Arecibo single-dish observations. We do not detect three of the four targeted LSB galaxies in HI down to a 4-sigma limit of 0.08Jy km/s. We find that two of the four of these LSBs have bright galaxies which have contaminated the Arecibo signal.

Dagomir Kaszlikowski, Darwin Gosal, E. J. Ling, L. C. Kwek

We present numerical data showing, that three qutrit correlations for a pure state, which is not maximally entangled, violate local realism more strongly than three-qubit correlations. The strength of violation is measured by the minimal amount of noise that must be admixed to the system so that the noisy correlations have a local and realistic model.

V. B. Bezerra, G. L. Klimchitskaya, V. M. Mostepanenko

We investigate the thermodynamical aspects of the Casimir effect in the case of plane parallel plates made of real metals. The thermal corrections to the Casimir force between real metals were recently computed by several authors using different approaches based on the Lifshitz formula with diverse results. Both the Drude and plasma models were used to descr

A. I. Pegarkov

The dynamics of molecular electron excitation and ionisation is studied in real-time for ultra-short IR laser pulses of intensity I>10^{13} W/cm^{2}. The multi-electron molecule is modeled by a system of two active electrons moving in a field of frozen core. The time dependences of electron probability, electron energy, and one-electron/two-electron ionisati

Oscar Bolina

We discuss the interchangeability of the thermodynamic limit β\to \infty and the infinite limit of the Trotter number n \to \infty when Trotter formula e^{H_{0}+V} =\lim_{n \to \infty} (e^{H_{0}/n} e^{V/n}) is used to calculate partition functions with Hamiltonians of the form H=H_{0}+V.

Jianwei Wang, Akhlesh Lakhtakia

The reflection of a normally incident wideband pulse by a half-space whose permittivity and permeability obey the one-resonance Lorentz model is calculated. The results are compared with those from frequency-domain reflection analysis. In the spectral regime wherein the real parts of the permittivity and the permeability are negative, as well as in small adj

B. Saghai, Z. Li

Within a chiral constituent quark formalism, allowing the inclusion of all known resonances, a comprehensive study of the recent eta photoproduction data on the proton up to 2 GeV is performed. This study shows evidence for a new S11 resonances and indicates the presence of an additional missing P13 resonance.

Jiro Soda

It is important to reveal the brane-bulk correspondence for understanding the brane world cosmology. When gravitational waves exist in the bulk, however, it is difficult to make the analysis of the interrelationship between the brane and the bulk. Hence, the minimal model which allows gravitational waves in the bulk would be useful. As for such models, we ad

E. O. Iltan

We study the form factors appearing in the inclusive decay b -> s g^*, in the framework of the noncommutative standard model. Here g^* denotes the virtual gluon. We get additional structures and the corresponding form factors in the noncommutative geometry. We analyse the dependencies of the form factors to the parameter pΘk where p (k) are the four momenta

Sanjay M. Wagh

Spacetimes admitting appropriate spatial homothetic Killing vectors are called spatially homothetic spacetimes. Such spacetimes conform to the fact that gravity has no length-scale for matter inhomogeneities. The matter density for such spacetimes is (spatially) arbitrary and the matter generating the spacetime admits {\it any} equation of state. Spatially h

Yu. P. Sukhorukov, E. A. Gan'shina, B. I. Belevtsev, N. N. Loshkareva

Transport, magnetic, magneto-optical (Kerr effect) and optical (light absorption) properties have been studied in an oriented polycrystalline La_{0.67}Ca_{0.33}MnO_{3} film which shows colossal magneto-resistance. The correlations between these properties are presented. A giant change in IR light transmission (more than a 1000-fold decrease) is observed on c

C. M. Varma, Elihu Abrahams

The equations in cond-mat/0011020 and Phys. Rev, Lett. 86, 4652 (2001) are valid but a numerical estimate in the paper is incorrect.

Emilia La Nave, Stefano Mossa, Francesco Sciortino

Depth, number, and shape of the basins of the potential energy landscape are the key ingredients of the inherent structure thermodynamic formalism introduced by Stillinger and Weber [F. H. Stillinger and T. A. Weber, Phys. Rev. A 25, 978 (1982)]. Within this formalism, an equation of state based only on the volume dependence of these landscape properties is

J. M. Migliazzo, B. M. Gaensler, D. C. Backer, B. W. Stappers

Using the Very Large Array and the Pie Town antenna, we have measured the position of the radio pulsar B1951+32 relative to nearby background radio sources at four epochs between 1989 and 2000. These data show a clear motion for the pulsar of (25 +/- 4) milliarcsec/yr at a position angle (252 +/- 7) degrees (north through east), corresponding to a transverse

Y. Aikawa, E. Herbst

We have investigated the two-dimensional (R,Z) distribution of deuterated molecular species in circumstellar disks around young stellar objects. The abundance ratios between singly deuterated and normal molecules (``D/H ratios'') in disks evolve in a similar way as in molecular clouds. Fractionation is caused by rapid exchange reactions that are exot

Y. Aikawa, N. Ohashi, S. Inutsuka, E. Herbst

We have investigated the evolution and distribution of molecules in collapsing prestellar cores via numerical chemical models, adopting the Larson-Penston solution and its delayed analogues to study collapse. Molecular abundances and distributions in a collapsing core are determined by the balance among the dynamical, chemical and adsorption time scales. Whe

Y. Aikawa, G. J. van Zadelhoff, E. F. van Dishoeck, E. Herbst

We have investigated molecular distributions in protoplanetary disks, adopting a disk model with a temperature gradient in the vertical direction. The model produces sufficiently high abundances of gaseous CO and HCO+ to account for line observations of T Tauri stars using a sticking probability of unity and without assuming any non-thermal desorption. In re

Haldan N. Cohn, Phyllis M. Lugger, Jonathan E. Grindlay, Peter D. Edmonds

We report results from HST-NICMOS imaging of the extremely dense core of the globular cluster Terzan 5. This highly obscured bulge cluster has been estimated to have one of the highest collision rates of any galactic globular cluster, making its core a particularly conducive environment for the production of interacting binary systems. We have reconstructed

Cheongho Han, Myeong-Gu Park

Gaudi, Naber & Sackett pointed out that if an event is caused by a lens system containing more than two planets, all planets will affect the central region of the magnification pattern, and thus the existence of the multiple planets can be inferred by detecting additionally deformed anomalies from intensive monitoring of high magnification events. Unfortunat

R. L. Leheny, Y. S. Lee, G. Shirane, R. J. Birgeneau

Inelastic neutron scattering with high wave-vector resolution has characterized the propagation of transverse spin wave modes near the antiferromagnetic zone center in the metastable domain state of a random field Ising magnet. A well-defined, long wavelength excitation is observed despite the absence of long-range magnetic order. Direct comparisons with the

Fariel Shafee

We have constructed a simple semiclassical model of neural network where neurons have quantum links with one another in a chosen way and affect one another in a fashion analogous to action potentials. We have examined the role of stochasticity introduced by the quantum potential and compare the system with the classical system of an integrate-and-fire model

J. Cuevas, F. Palmero, J. F. R. Archilla, F. R. Romero

We study the properties of moving breathers in a bent DNA-related model with short range interaction, due to the stacking of the base pairs, and long range interaction, due to the finite dipole moment of the bonds within each base pair. We show that the movement of a breather is hindered by the bending of the chain as a particle in a potential barrier. We ha

A. Alvarez, J. F. R. Archilla, J. Cuevas, F. R. Romero

Discrete bright breathers are well known phenomena. They are localized excitations that consist of a few excited oscillators in a lattice and the rest of them having very small amplitude or none. In this paper we are interested in the opposite kind of localization, or discrete dark breathers, where most of the oscillators are excited and one or a few units o

Kunihito Ioka, Takashi Nakamura

We show that if the intrinsic break energy of Gamma-Ray Bursts (GRBs) is determined by the product of more than three random variables the observed break energy distribution becomes almost lognormal including the redshift effect because of the central limit theorem. The excess from the lognormal distribution at the low break energy is possibly due to the hig

Takeshi Nihei, Leszek Roszkowski, Roberto Ruiz de Austri

We derive a full set of exact, analytic expressions for the annihilation of the lightest neutralino pairs into all two-body tree-level final states in the framework of minimal supersymmetry. We make no simplifying assumptions about the neutralino nor about sfermion masses and mixings other than the absence of explicit CP--violating terms. The expressions sho

J. -Y. Lin, P. L. Ho, H. L. Huang, P. H. Lin

The low-temperature specific heat C(T,H) of a new superconductor MgCNi3 has been measured in detail. (C/gammasub_nTc=1.97 is estimated from the anomaly at Tc. At low temperatures, the electronic contribution in the superconducting state follows Ces/gammasub_nTc=7.96exp(-1.46Tc/T). The magnetic field dependence of gamma(H) is found to be linear with respect t

Belle collaboration, K. Abe

The lifetimes of the B0bar and B- mesons are extracted from 29.1/fb of data collected with the Belle detector at the KEK B-factory. A fit to the decay length differences of neutral and charged B meson pairs, measured in events where one of the B mesons is fully reconstructed in several hadronic modes, yields tau_B0bar = 1.554 +/- 0.030(stat) +/- 0.019(syst)

Ikuo Ichinose, Tetsuo Matsui

The quasiexcitations of quantum Hall systems at the filling factor $ν= p/(2pq \pm 1)$ are studied in terms of chargeon and fluxon introduced previously as constituents of an electron at $ν= 1/2$. At temperatures $T < T_{\rm PFS}(ν)$, the phenomenon so-called particle-flux separation takes place, and chargeons and fluxons are deconfined to behave as quasipart

Kim Griest

It is a mystery why the density of matter and the density of vacuum energy are nearly equal today when they scale so differently during the expansion of the Universe. We suggest a paradigm that might allow for a non-anthropic solution to this cosmic coincidence problem. The fact that the half life of Uranium 238 is very near to the age of the solar system is

Srihari Keshavamurthy, Nicholas R. Cerruti, Steven Tomsovic

Numerous experimental and theoretical studies have established that intramolecular vibrational energy redistribution (IVR) in isolated molecules has a heirarchical tier structure. The tier structure implies strong correlations between the energy level motions of a quantum system and its intensity-weighted spectrum. A measure, which explicitly accounts for th

Yurii A. Neretin

Consider the Plancherel decomposition of the tensor product of a highest weight and a lowest weight unitary representations of $SL_2$. We construct explicitly the action of the Lie algebra $sl_2 + sl_2$ in the direct integral of Hilbert spaces. It turns out that a Lie algebra operator is a second order differential operator in one variable and second order d

Michele Grassi

We introduce self-dual manifolds and show that they can be used to encode mirror symmetry for affine-Kähler manifolds and for elliptic curves. Their geometric properties, especially the link with special lagrangian fibrations and the existence of a transformation similar to the Fourier-Mukai functor, suggest that this approach may be able to explain mirror s

Drastich Stanislav

Studying Fermat sequence we can simply find infinitely many other rapidly growing sequences of similar properties. On the other hand this approach allows us simple construction of such sequences.

Corneliu Sochichiu

The role of the gauge invariance in noncommutative field theory is discussed. A basic introduction to noncommutative geometry and noncommutative field theory is given. Background invariant formulation of Wilson lines is proposed. Duality symmetries relating various noncommutative gauge models are being discussed.

Han-xin He

The nonperturbative fermion-boson vertex function in four-dimensional Abelian gauge theories is self-consistently and exactly derived in terms of a complete set of normal (longitudinal) and transverse Ward-Takahashi relations for the The nonperturbative fermion-boson vertex function in four-dimensional Abelian gauge theories is self-consistently and exactly

E. G. Adelberger

Sub-mm tests of the gravitational inverse-square law are interesting from several quite different perspectives. This paper discusses work by the Eot-Wash group performed since the publication of our initial result in February 2001. We find no evidence for short-range Yukawa interactions. Our results provide an upper limit of 200 micrometers on the size of th

Mauricio Bellini

I study the possibility of baryogenesis can take place in fresh inflation. I find that it is possible that violation of baryon number conservation can occur during the period out-of-equilibrium in this scenario. Indeed, baryogenesis could be possible before the thermal equilibrium is restored at the end of fresh inflation.

A. Accioly, H. Blas, H. Mukai

It is shown that the exact Foldy-Wouthuysen transformation for spin-0 particles on spacetimes described by the metrics $ds^2 = V^2 dt^2 - W^2 d {\bf{x}}^2$, where $V=V({\bf{x}})$ and $W=W({\bf{x}})$, only exists if the scalar field is nonminimally coupled to the Ricci scalar field with a coupling constant equal to 1/6. The nonminimal coupling term, in turn,

Sanjay M Wagh

Gravity does not provide any scale for matter properties. We argue that this is also the implication of Mach&#39;s hypothesis of the relativity of inertia. The most general spacetime compatible with this property of gravity is that admitting three, independent spatial homothetic Killing vectors generating an arbitrary function of each one of the three spatia

L. V. Verozub

A metric-field approach to gravitation is presented. It is based on an idea of dependency of space-time properties on measuring instruments. Some bimetric equations that realize this idea are considered. They were tested by the binary pulsar PSR1913+16. The spherically - symmetric solution of the equations has no event horizon and no physical singularity in

A. T. Savici, Y. Fudamoto, I. M. Gat, T. Ito

This paper reports muon spin relaxation (MuSR) measurements of two single crystals of the title high-Tc cuprate systems where static incommensurate magnetism and superconductivity coexist. By zero-field MuSR measurements and subsequent analyses with simulations, we show that (1) the maximum ordered Cu moment size (0.36 Bohr magneton) and local spin structure

Dietrich Stauffer

The Sznajd model in less than a year has found several followers. An isolated person does not convince others; a group of people sharing the same opinions influences the neighbours much more easily. Thus on a square lattice, with variables +1 (Democrats) and --1 (Republicans) on every lattice site, a pair (or plaquette) of neighbours convinces its six (eight

Won Woo Kim, Jeong Won Kang, Tae Won Kim, Ho Jung Hwang

We have simulated the tensile testing of cylindrical multi-shell Cu nanowire. Elongated cylindrical multi-shell Cu nanowire was transformed into a pentagonal structure. Pentagonal nanowires are composed of a central atomic strand and pentagonal tubes made of five-times-folded <110>{100} sheets.

Jeong Won Kang, Ho Jung Hwang

In order to understand properties of ultrathin copper nanowires, we have simulated several copper nanowires using classical molecular dynamic simulations. As the temperature increases, copper nanowires were transformed into structures of the lowest surface stresses and surface energy, circular cross-section with {111}-like surface. As thickness of copper nan

A. Bharathi, S. Jemima Balaselvi, S. Kalavathi, G. L. N. Reddy

Successful replacement of B by C in the series MgB2-xCx for values of x upto 0.3 are reported. Resistivity and ac susceptibility measurements have been carried out in the samples. Solubility of carbon, inferred from the observed change in the lattice parameter with carbon content indicates that carbon substitutes upto x=0.30 into the MgB2 lattice. The superc

Markus Deserno, Hans-Hennig von Grunberg

We study theoretically the osmotic pressure of a suspension of charged objects (e.g., colloids, polyelectrolytes, clay platelets, etc.) dialyzed against an electrolyte solution using the cell model and linear Poisson-Boltzmann (PB) theory. From the volume derivative of the grand potential functional of linear theory we obtain two novel expressions for the os

Kaushik Matia, Luis A. Nunes Amaral, Stephen P. Goodwin, H. Eugene Stanley

Price fluctuations of commodities like cotton and wheat are thought to display probability distributions of returns that follow a Lévy stable distribution. Recent analysis of stocks and foreign exchange markets show that the probability distributions are not Lévy stable, a plausible result since commodity markets have quite different features than stock mark

Baolin Wang, Guanghou Wang, Jijun Zhao

The structures of free-standing zirconium nanowires with 0.6$-$2.8 nm in diameter are systematically studied by using genetic algorithm simulations with a tight-binding many body potential. Several multi-shell growth sequences with cylindrical structures are obtained. These multi-shell structures are composed of coaxial atomic shells with the three- and four

Sanjay M Wagh

In this paper, we consider the problems of spherical gravitational collapse and accretion using a spherically symmetric, spatially homothetic spacetime, that is, as an exact solution (cqg1) of the field equations of general relativity. Properties of matter like its equation of state determine whether the collapse becomes unstoppable or not since the spacetim

Jack Xin, Yingyong Qi, Li Deng

A nonlinear nonlocal cochlear model of the transmission line type is studied in order to capture the multitone interactions and resulting tonal suppression effects. The model can serve as a module for voice signal processing, it is a one dimensional (in space) damped dispersive nonlinear PDE based on mechanics and phenomenology of hearing. It describes the m

Oleg Y. Gnedin, HongSheng Zhao, J. E. Pringle, S. Michael Fall

Using current observational data and simple dynamical modeling, we demonstrate that Omega Cen is not special among the Galactic globular clusters in its ability to produce and retain the heavy elements dispersed in the AGB phase of stellar evolution. The multiple stellar populations observed in Omega Cen cannot be explained if it had formed as an isolated st

Gustavo A. Lara, Pedro A. Orellana, Enrique V. Anda

Electron tunneling through a non-equilibrium double quantum dot in the Kondo regime is studied. In the region of negative differential resistance, it is shown that this system possesses a complex response to the applied potential characterized by a tristable solution for the current. Increasing the applied potential or reducing the inter-dot coupling, the sy

Massimo Bianchi, Michael B. Green, Stefano Kovacs

It is argued that whereas supersymmetry requires the instanton contribution to the expectation value of a straight Wilson line in the N=4 supersymmetric SU(2) Yang-Mills theory to vanish, it is not required to vanish in the case of a circular Wilson loop. A non-vanishing value can arise from a subtle interplay between a divergent integral over bosonic moduli

F. M. Liu, J. Aichelin, M. Bleicher, H. J. Drescher

The recent data on pp collisions at 158 GeV provide severe constraints on string models: These measurements allow for the first time to determine how color strings are formed in ultrarelativistic proton-proton collisions.

R. E. Rothschild, R. E. Lingenfelter

Two long observations of Cas A supernova remnant were made by the \emph{Rossi X-ray Timing Explorer} in 1996 and 1997 to search for hard X-ray line emission at 67.9 and 78.4 keV from decay of $^{44}$Ti formed during the supernova event. Continuum flux was detected up to 100 keV, but the $^{44}$Ti lines were not detected. The 90% confidence upper limit to the

David Tong

N=2 SQED with several flavors admits multiple, static BPS domain wall solutions. We determine the explicit two-kink metric and examine the dynamics of colliding domain walls. The multi-kink metric has a toric Kahler structure and we reduce the Kahler potential to quadrature. In the second part of this paper, we consider semi-local vortices compactified on ci

F. Ruiz Ruiz

Noncommutative IR singularities and UV/IR mixing in relation with the Goldstone theorem for complex scalar field theory are investigated. The classical model has two coupling constants, $λ_1$ and $λ_2$, associated to the two noncommutative extensions $ϕ^*\starϕ\starϕ^*\starϕ$ and $ϕ^*\starϕ^*\starϕ\starϕ$ of the interaction term $|ϕ|^4$ on commutative spacet

M. Cadoni, P. Carta, S. Mignemi

A model of matter-coupled gravity in two dimensions is quantized. The crucial requirement for performing the quantization is the vanishing of the conformal anomaly, which is achieved by tuning a parameter in the interaction potential. The spectrum of the theory is determined by mapping the model first onto a field theory with a Liouville interaction, then on

Christian Hainzl

We investigate the ground state energy of an electron coupled to a photon field. First, we regard the self-energy of a free electron, which we describe by the Pauli-Fierz Hamiltonian. We show that, in the case of small values of the coupling constant $α$, the leading order term is represented by $2π^{-1} α(Λ- \ln[1 + Λ])$. Next we put the electron in the fie