April 2002 arXiv papers — page 16

Paul S. Wesson

A null path in 5D can appear as a timelike path in 4D, and for a certain gauge in 5D the motion of a massive particle in 4D obeys the usual quantization rule with an uncertainty-type relation. Generalizations of this result are discussed in regard to induced-matter and membrane theory.

J. D. Brown, S. R. Lau, J. W. York

We present a detailed examination of the variational principle for metric general relativity as applied to a ``quasilocal'' spacetime region $\M$ (that is, a region that is both spatially and temporally bounded). Our analysis relies on the Hamiltonian formulation of general relativity, and thereby assumes a foliation of $\M$ into spacelike hypersurfa

Joseph R. Kiniry

Building complex software systems necessitates the use of component-based architectures. In theory, of the set of components needed for a design, only some small portion of them are "custom"; the rest are reused or refactored existing pieces of software. Unfortunately, this is an idealized situation. Just because two components should work together d

Joseph R. Kiniry

Semantic properties are domain-specific specification constructs used to augment an existing language with richer semantics. These properties are taken advantage of in system analysis, design, implementation, testing, and maintenance through the use of documentation and source-code transformation tools. Semantic properties are themselves specified at two lev

Joseph R. Kiniry

A major part of debugging, testing, and analyzing a complex software system is understanding what is happening within the system at run-time. Some developers advocate running within a debugger to better understand the system at this level. Others embed logging statements, even in the form of hard-coded calls to print functions, throughout the code. These tec

Krzysztof C. Kiwiel

We show that several versions of Floyd and Rivest's algorithm Select for finding the $k$th smallest of $n$ elements require at most $n+\min\{k,n-k\}+o(n)$ comparisons on average and with high probability. This rectifies the analysis of Floyd and Rivest, and extends it to the case of nondistinct elements. Our computational results confirm that Select may

Daniel Lehmann

Tarski gave a general semantics for deductive reasoning: a formula a may be deduced from a set A of formulas iff a holds in all models in which each of the elements of A holds. A more liberal semantics has been considered: a formula a may be deduced from a set A of formulas iff a holds in all of the "preferred" models in which all the elements of A h

Matthias Schmidt, Alan R. Denton

The influence of poor solvent quality on fluid demixing of a model mixture of colloids and nonadsorbing polymers is investigated using density functional theory. The colloidal particles are modelled as hard spheres and the polymer coils as effective interpenetrating spheres that have hard interactions with the colloids. The solvent is modelled as a two-compo

Clécio C. de Souza Silva, Gilson Carneiro

Melting of moving vortex lattices in clean superconducting films with periodic pinning is studied by a dynamical "cage" model, based on a mean-field treatment of Langevin's equations for the whole vortex lattice, assuming elastic flow. In the frame moving with the velocity of the vortex lattice center of mass, the model describes forced vibration

C. Brechignac, Ph. Cahuzac, F. Carlier, C. Colliex

Formation and evolution of fragmentation instabilities in fractal islands, obtained by deposition of silver clusters on graphite, are studied. The fragmentation dynamics and subsequent relaxation to the equilibrium shapes are controlled by the deposition conditions and cluster composition. Sharing common features with other materials' breakup phenomena,

S. Gluzman, D. Sornette, V. I. Yukalov

We apply the technique of self-similar exponential approximants based on successive truncations of continued exponentials to reconstruct functional laws of the quasi-exponential class from the knowledge of only a few terms of their power series. Comparison with the standard Padé approximants shows that, in general, the self-similar exponential approximants p

Wolfgang R. Bauer, Walter Nadler

For Markovian dynamics of field fluctuations we present here an extended strong collision approximation, thereby putting our previous strong collision approach (Phys. Rev. Lett. 83 (1999) 4215) into a systematic framework. Our new approach provides expressions for the free induction and spin echo magnetization decays that may be solved analytically or at lea

V. L. Kulinskii, N. P. Malomuzh

The model of dipole fluid for the ionic liquids similar to the molten NaCl is proposed. The estimates for the critical parameters are obtained with the help of the van der Waals equation of state. The influence of the rotation on the characteristics of a dipole pair and the location of the critical point is discussed. The dissociation of such fluid near the

O. Usmani, E. Lutz, M. Buttiker

We consider a classical overdamped Brownian particle moving in a symmetric periodic potential. We show that a net particle flow can be produced by adiabatically changing two external periodic potentials with a spatial and a temporal phase difference. The classical pumped current is found to be independent of the friction and to vanish both in the limit of lo

Balázs Dóra, Kazumi Maki, Bojana Korin-Hamzic, Mario Basletic

In spite of extensive experimental studies of the angular dependent magnetoresistance (ADMR) of the low temperature phase (LTP) of alpha-(BEDT-TTF)_2KHg(SCN)_4 about a decade ago, the nature of LTP remains elusive. Here we present a new study of ADMR of LTP in alpha-(ET)_2 salts assuming that LTP is unconventional charge density wave (UCDW). In the presence

J. V. Alvarez, Claudius Gros

We discuss zero-frequency transport properties of various spin-1/2 chains. We show, that a careful analysis of Quantum Monte-Carlo (QMC) data on the imaginary axis allows to distinguish between intrinsic ballistic and diffusive transport. We determine the Drude weight, current-relaxation life-time and the mean-free path for integrable and a non-integrable qu

Geza Toth, Colin Denniston, J. M. Yeomans

We formulate a lattice Boltzmann algorithm which solves the hydrodynamic equations of motion for nematic liquid crystals. The applicability of the approach is demonstrated by presenting results for two liquid crystal devices where flow has an important role to play in the switching.

Kunal K. Das, M. D. Girardeau, E. M. Wright

We develop a variational theory of the crossover from the one-dimensional (1D) regime to the 3D regime for ultra-cold Bose gases in thin waveguides. Within the 1D regime we map out the parameter space for fermionization, which may span the full 1D regime for suitable transverse confinement.

Takashi Yanagisawa, Shigeru Koikegami, Hajime Shibata, Shinji Kimura

Opticcal conductivity spectra $σ_1(ω)$ of Nd2-xCexCuO4 thin films, measured by the reflectance-transmittance method (R-T method) which has been proposed to investigate far-infrared spectroscopy, are investigated based on the anisotropic pairing model. Precise measurements of the frequency-dependent conductivity enable us to examine quantitatively the nature

Toshimasa Fujisawa, David Guy Austing, Yasuhiro Tokura, Yoshiro Hirayama

We investigate non-equilibrium transport in the absence of spin-flip energy relaxation in a few-electron quantum dot artificial atom. Novel non-equilibrium tunneling processes involving high-spin states which cannot be excited from the ground state because of spin-blockade, and other processes involving more than two charge states are observed. These process

K. Bernardet, G. G. Batrouni, M. Troyer, A. Dorneich

We use quantum Monte Carlo simulations to study the effect of disorder, in the form of a disordered chemical potential, on the phase diagram of the hard core bosonic Hubbard model in two dimensions. We find numerical evidence that in two dimensions, no matter how weak the disorder, it will always destroy the long range density wave order (checkerboard solid)

Michele Cini, Gianluca Stefanucci

In two-dimensional systems possessing a high degree of symmetry, the repulsive electron-electron interaction produces a pairing force; the mechanism would fail in the presence of strong distortions. We have studied this in the one-band and three-band Hubbard Model. From partially occupied orbitals one obtains pair eigenstates of the Hamiltonian with no on-si

P. Sindzingre, J. -B. Fouet, C. Lhuillier

Exact diagonalizations indicate that the effective 1-dimensional behavior (sliding Luttinger liquid phase) of the frustrated spin-1/2 crossed chain model, predicted by Starykh, Singh and Levine [Phys. Rev. Lett. 88, 167203 (2002)], persists for a wide range of transverse couplings. The extension of the other phases (plaquette valence bond crystal and Néel lo

Peter Rupp, Reinhard Richter, Ingo Rehberg

A new experimental system showing a transition to spatiotemporal intermittency is presented. It consists of a ring of hundred oscillating ferrofluidic spikes. The measured critical exponents of the system agree with those obtained from a theoretical model of directed percolation.

K. Goral, L. Santos, M. Lewenstein

The ground state of dipolar bosons placed in an optical lattice is analyzed. We show that the modification of experimentally accessible parameters can lead to the realization and control of different quantum phases, including superfluid, supersolid, Mott insulator, checkerboard, and collapse phases.

Inseok Song, A. Weinberger, E. Becklin, B. Zuckerman

We carried out a search for M-type Vega-like stars by correlating the IRAS Faint Source Catalog with Hipparcos selected M-type stars. Three stars with apparent IRAS 25mu excess emission are shown instead to be non-IR-excess stars from ground-based 11.7 and 17.9mu photometry. Two stars previously suggested to have Vega-like mid-IR excess are also shown to be

Mikhail V. Medvedev, Norman Murray

We study the structure and properties of hot MHD accretion onto a Kerr black hole. In such a system, the hole is magnetically coupled to the inflowing gas and exerts a torque onto the accretion flow. A hot settling flow can form around the hole and transport the angular momentum outward, to the outer edge of the flow. Unlike other hot flows, such as advectio

C. Carilli, P. Cox, F. Bertoldi, K. M. Menten

We present observations of CO 1-0 and CO 2-1 emission from the z = 4.12 QSO PSS 2322+1944 using the Very Large Array. The CO emission is extended on a spatial scale of 2''. This extension could reflect the double nature of the QSO as seen in the optical, or could be diffuse emission with a (redshift corrected) mean brightness temperature of 2.8 K for

Konstantin V. Getman, Eric D. Feigelson, Leisa Townsley, John Bally

NGC 1333, a highly active star formation region within the Perseus molecular cloud complex, has been observed with the ACIS-I detector on board the Chandra X-ray Observatory. In our image with a sensitivity limit of ~ 1e28 erg/s, we detect 127 X-ray sources, of which, 95 are known cluster members. The X-ray luminosity function of the discovered YSO populatio

M. Brusa, A. Comastri, E. Daddi, A. Cimatti

We present preliminary results of a 25 ks XMM-Newton observation of the largest sample of Extremely Red Objects (EROs) available to date (about 450 sources), selected in a contiguous area of 700 arcmin^2 (Daddi et al. 2000). Five of the 36 hard X-ray selected sources brighter than 7x10^{-15} erg cm^{-2} s^{-1} in the 2-10 keV band are associated with EROs. A

Luis J. Goicoechea

Q0957+561A,B is a double-imaged quasar that has been intensively observed during the last 10 years in different optical bands and with several telescopes, and we concentrated on recent public data obtained at the Apache Point Observatory (APO) and the Teide Observatory (TO). When an intrinsic event appears in the light curve of Q0957+561A, its twin event (a

H. R. Schmitt, J. E. Pringle, C. J. Clarke, A. L. Kinney

We use HST broad band images, VLA and VLBI continuum data to study the three dimensional orientation of jets relative to nuclear dust disks in 20 radio galaxies. The comparison between the position angles of the jets with those of the dust disks major axes shows a wide distribution, suggesting that they are not aligned preferentially perpendicular to each ot

F. Derue, J. B. Marquette, S. Lupone, C. Afonso

We present the results of a massive variability search based on a photometric survey of a six square degree region along the Galactic plane at ($l = 305^\circ$, $b = -0.8^\circ$) and ($l = 330^\circ$, $b = -2.5^\circ$). This survey was performed in the framework of the EROS II (Expérience de Recherche d'Objets Sombres) microlensing program. The variable

J. M. Girart, S. Viti, D. A. Williams, R. Estalella

We present a CSO and BIMA molecular line survey of the dense, quiescent molecular environment ahead of HH2. The molecular gas is cold, 13 K, and moderately dense, 3x10^5 cm^-3. A total of 14 species has been detected (including different isotopes and deuterated species). The relative abundances of the clump are compared with other dense molecular environment

G. Bono, F. Caputo, V. Castellani, M. Marconi

We show that a straightforward application of the predicted relation connecting the absolute K magnitude of fundamental RR Lyrae variables to their period and metal content, together with current evolutionary predictions on the mass and luminosity of Horizontal Branch stars, supply a distance estimate to the prototype star RR Lyr in close agreement with the

K. Dennerl, U. G. Briel, M. J. Freyberg, F. Haberl

The pn camera of EPIC is inherently robust against radiation damage effects. Nevertheless, the knowledge of charge transfer inefficiency (CTI) of the pn camera is crucial for obtaining the correct energy scale. We describe detailed in-orbit monitoring of this effect, utilizing the internal calibration source. We find that during the first two years in orbit

A. Contursi, M. J. Kaufman, G. Helou, D. J. Hollenbach

(Abridged) We present the analysis of the main FIR fine structure lines emission in NGC1313 and NGC6946. We calculate that a component probably associated with the diffuse disks contributes <~40% in N6946 and ~30 % in N1313 to the total [CII] emission. The main PDR physical parameters responsible for the neutral atomic gas emission in N1313 and N6946 do not

B. Semelin, F. Combes

The formation and evolution of galactic disks are complex phenomena, where gas and star dynamics are coupled through star formation and the related feedback. The physical processes are so numerous and intricate that numerical models focus, in general, on one or a few of them only. We propose here a numerical model with particular attention to the multiphase

D. J. Morris, G. Hobbs, A. G. Lyne, I. H. Stairs

The Parkes multibeam pulsar survey is a sensitive survey of a strip of the Galactic plane with $|b|<5\degr$ and $260\degr < l < 50\degr$ at 1374 MHz. Here we report the discovery of 120 new pulsars and subsequent timing observations, primarily using the 76-m Lovell radio telescope at Jodrell Bank. The main features of the sample of 370 published pulsars disc

K. Dennerl, V. Burwitz, J. Englhauser, C. Lisse

On January 10 and 13, 2001, Venus was observed for the first time with an X-ray astronomy satellite. The observation, performed with the ACIS-I and LETG/ACIS-S instruments on Chandra, yielded data of high spatial, spectral, and temporal resolution. Venus is clearly detected as a half-lit crescent, with considerable brightening on the sunward limb. The morpho

J. M. Pittard, I. R. Stevens

We investigate which shocked wind is responsible for the majority of the X-ray emission in colliding wind binaries, an issue where there is some confusion in the literature, and which we show is more complicated than has been assumed. We find that where both winds rapidly cool (typically close binaries), the ratio of the wind speeds is often more important t

Thomas J. Maccarone, Paolo S. Coppi

We present three spectra of Cygnus X-1 in the low/hard state from 3-1000 keV produced with RXTE and OSSE. We demonstrate that a pure thermal Comptonization model, with Compton reflection fits the data well, with coronal temperatures of about 90 keV, optical depths of about 1.3, and reflection fractions of about 0.25 $\times$ 2$π$. We find that no additional

P. M. Garnavich, K. Z. Stanek, L. Wyrzykowski, L. Infante

We present the discovery and follow-up observations of the afterglow of the GRB 011121 and its associated supernova SN 2001ke. Images were obtained with the OGLE 1.3m telescope in BVRI passbands, starting 10.3 hours after the burst. The temporal analysis of our early data indicates a steep decay, independent of wavelength with power-law index alpha=-1.72+/-0

Andrew Gould, Samir Salim

We outline the construction of an updated version of the New Luyten Two-Tenths (NLTT) catalog of high proper motion stars, which will contain improved astrometry and photometry for the vast majority of the ~59,000 stars in NLTT. The bright end is constructed by matching NLTT stars to Hipparcos, Tycho-2, and Starnet; the faint end by matching to USNO-A and 2M

Maulik K. Parikh

We introduce a simple coordinate system covering half of de Sitter space. The new coordinates have several attractive properties: the time direction is a Killing vector, the metric is smooth at the horizon, and constant-time slices are just flat Euclidean space. We demonstrate the usefulness of the coordinates by calculating the rate at which particles tunne

Bhag C. Chauhan

Assuming the solar neutrino deficit is resolved by the resonant interaction of the neutrino magnetic moment with the solar magnetic field --in the framework of Resonant Spin Flavour Precession (RSFP) scenario-- the solar magnetic field profile function has been derived from the scenario in the light of solar neutrino data. An approximate qualitative analysis

Matthias Vojta

Motivated by recent neutron scattering and scanning tunneling microscopy (STM) experiments on cuprate superconductors, we discuss charge-ordered states, in particular with two-dimensional charge modulation patterns, co-existing with superconductivity. We extend previous studies of a large-N mean-field formulation of the t-J model. In addition to bond-centere

Helmut G. Katzgraber

In this paper I report results for simulations of the three-dimensional gauge glass and the four-dimensional XY spin glass using the parallel tempering Monte Carlo method at low temperatures for moderate sizes. The results are qualitatively consistent with earlier work on the three- and four-dimensional Edwards-Anderson Ising spin glass. I find evidence that

Z. G. Wang

In this article, we calculate the dressed quark propagator with the flat bottom potential in the framework of the rain-bow Schwinger-Dyson equation, which is determined by mean field approximation of the global colour model lagrangian. The dressed quark propagator exhibits a dynamical symmetry breaking phenomenon and gives a constituent quark mass about 392

S. Bondarenko, E. Levin, J. Nuiri

We use the Constituent Quark Model (CQM) to describe CDF data on double parton cross section and HERA data on the $ J / Ψ$ ratio cross section of elastic and inelastic diffractive productions. Our estimate shows that the radius of the constituent quark turns out to be rather small, $R^2_{quark} \approx 0.1 Gev^{-2}$, in accordance with the assumption on whic

Mahendra K. Verma, Arvind Ayyer, Olivier Debliquy, Shishir Kumar

In this paper we analytically compute the strength of nonlinear interactions in a triad, and the energy exchanges between wavenumber shells in incompressible fluid turbulence. The computation has been done using first-order perturbative field theory. In three dimension, magnitude of triad interactions is large for nonlocal triads, and small for local triads.

Doron Cohen, Diego A. Wisniacki

We study the evolution of the energy distribution for a stadium with moving walls. We consider one period driving cycle, which is characterized by an amplitude $A$ and wall velocity $V$. This evolving energy distribution has both &#34;parametric&#34; and &#34;stochastic&#34; components. The latter are important for the theory of quantum irreversibility and d

Kazuya Koyama

We investigate the effect of the radion on cosmological perturbations in the brane world. The S^1/Z_2 compactified 5D Anti-de Sitter spacetime bounded by positive and negative tension branes is considered. The radion is the relative displacement of the branes in this model. We find two different kinds of the radion at the linear perturbation order for a cosm

Henric Krawczynski, Paolo S. Coppi, Felix Aharonian

If the high-energy emission from TeV blazars is produced by the Synchrotron Self-Compton (SSC) mechanism, then simultaneous X-ray and Gamma-ray observations of these objects are a powerful probe of the electron (and/or positron) populations responsible for this emission. Understanding the emitting particle distributions and their evolution in turn allow us t

Masato Ito

We consider a single brane embedded in five dimensions with vanishing and positive bulk cosmological constant. In this setup, the existence of $dS_{4}$ brane is allowed. We explore the gravitational fluctuations on the brane, and we point out that the usual four-dimensional gravity can be reproduced by a normalizable zero mode and that the continuous massive

P. L. Chapovsky, L. J. F. Hermans

Except for ortho- and para-H2, very little is known about nuclear spin isomers (or spin modifications) of molecules. The main reason is the lack of practical enrichment techniques. Recently a few enrichment methods were developed, which opened up new possibilities in the field. These methods are briefly reviewed. Substantial progress in the field has been ma

Mahendra K. Verma, Gaurav Dar, V. Eswaran

Biskamp and Schwarz [Phys. Plasmas, 8, 3282 (2001)] have reported that the energy spectrum of two-dimensional magnetohydrodynamic turbulence is proportional to $k^{-3/2}$, which is a prediction of Iroshnikov-Kraichnan phenomenology. In this comment we report some earlier results which conclusively show that for two-dimensional magnetohydrodynamic turbulence,

Hiraku Nakajima

We give a tableaux sum expression of $t$--analog of $q$--characters of finite dimensional representations (standard modules) of quantum affine algebras $\Ul$ when $\g$ is of type $A_n$, $D_n$.

Mikhail Katz

We prove the simultaneous (k,n-k)-systolic freedom, for a pair of adjacent integers k smaller than n/2, of a simply connected n-manifold X. Our construction, related to recent results of I. Babenko, is concentrated in a neighborhood of suitable k-dimensional submanifolds of X. We employ calibration by differential forms supported in such neighborhoods, to pr

Victor Bangert, Mikhail Katz

Multiplicative relations in the cohomology ring of a manifold impose constraints upon its stable systoles. Given a compact Riemannian manifold (X,g), its real homology H_*(X,R) is naturally endowed with the stable norm. Briefly, if h\in H_k(X,R) then the stable norm of h is the infimum of the Riemannian k-volumes of real cycles representing h. The stable k-s

Alexandre V. Borovik, Alexei G. Myasnikov, Vladimir N. Remeslennikov

We introduce a family of atomic measures on free groups generated by no-return random walks. These measures are shown to be very convenient for comparing &#34;relative sizes&#34; of subgroups, context-free and regular subsets (that, subsets generated by finite automata) of free groups. Many asymptotic characteristics of subsets and subgroups are naturally ex

Hiraku Nakajima

Let us consider a specialization of an untwisted quantum affine algebra of type $ADE$ at a nonzero complex number, which may or may not be a root of unity. The Grothendieck ring of its finite dimensional representations has two bases, simple modules and standard modules. We identify entries of the transition matrix with special values of ``computable&#39;&#3

N. E. Mavromatos

I review cosmology within the framework of type-0 non-critical strings, proposed in collaboration with G. Diamandis, B. Georgalas, E. Papantonopoulos and I. Pappa. The instabilities of the tachyonic backgrounds, due to the absence of space-time supersymmetry, are treated in this framework as a necessary ingredient to ensure cosmological flow. The model invol

Dmitri Antonov

The (2+1)D Georgi-Glashow model is explored at finite temperature in the regime when the Higgs boson is not infinitely heavy. The resulting Higgs-mediated interaction of monopoles leads to the appearance of a certain upper bound for the parameter of the weak-coupling approximation. Namely, when this bound is exceeded, the cumulant expansion used for the aver

Harald Appelshäuser

Recent results from the CERES experiment at the SPS are reviewed. Emphasis is put on the centrality and beam energy dependence, and the results are put into perspective with findings at lower and higher beam energies. The rather weak beam energy dependence of the HBT radii maybe understood in terms of a transition from baryon to pion dominated freeze-out. Th

Z. G. Wang, S. L. Wan

In this article, we calculate the dressed quark propagator with the flat bottom potential in the framework of the rain-bow Schwinger-Dyson equation. Then based on the nonperturbative dressed quark propagator, we calculate the $π$ decay constant and the quark condensate. The $π$ decay constant is an important parameter in describing the interplay between dyna

Yu. V. Dumin

Search for the mechanisms suppressing formation of Higgs field defects (e.g. domain walls) during the cosmological phase transitions is one of key problems in explanation of the observed large-scale uniformity of the space-time. One of the possible solutions can be based on accounting for Einstein-Podolsky-Rosen (EPR) correlations. Namely, if a coherent quan

Chongxing Yue, Hong Li, Yanming Zhang, Yong Jia

In the context of flavor-universal topcolor-assisted technicolor (TC2) models, we calculate the lepton flavor violating (LFV) $Z\to l_il_j$ decays. We find that the extra U(1) gauge boson $Z^{\prime}$ can give significant contributions to these LFV processes. With reasonable values of the parameters, the branching ratios of the processes $Z\to τμ$ and $Z\to

Subir Sarkar

From an observational perspective cosmology is today in excellent shape - advances in instrumentation and data processing have enabled us to study the universe in detail back to when the first galaxies formed, map the fluctuations in the cosmic microwave background which provide a measure of the overall geometry, and reconstruct the thermal history reliably

Michael Freund, Daniel Lehmann

The (extended) AGM postulates for belief revision seem to deal with the revision of a given theory K by an arbitrary formula, but not to constrain the revisions of two different theories by the same formula. A new postulate is proposed and compared with other similar postulates that have been proposed in the literature. The AGM revisions that satisfy this ne

Ken Katkin

In 1999, the FCC authorized direct access to INTELSAT, allowing INTELSAT&#39;s U.S. customers and competitors to bypass INTELSAT&#39;s U.S. retail affiliate (COMSAT), and to take satellite capacity at wholesale prices directly from INTELSAT. This policy was modeled in many respects on the access and unbundling requirements applicable to domestic incumbent lo

A. Gozar

Magnetic Raman scattering in two-leg spin ladder materials and the relationship between the anisotropic exchange integrals are analyzed by P. J. Freitas and R. R. P. Singh in Phys. Rev. B, {\bf 62}, 14113 (2000). The angular dependence of the two-magnon scattering is shown to provide information for the magnetic anisotropy in the Sr_14Cu_24O_41 and La_6Ca_8C

Ernst Helmut Brandt, Grigorii P. Mikitik

We show that for a thin superconducting strip placed in a transverse dc magnetic field - the typical geometry of experiments with high-Tc superconductors - the application of a weak ac magnetic field perpendicular to the dc field generates a dc voltage in the strip. This voltage leads to the decay of the critical currents circulating in the strip, and eventu

E. L. Nagaev

The magnetic strings in antiferromagnetic crystals with the spin $S = 1 /2$ differ from the magnetic polarons (ferrons) by the absence of the additional magnetic moment. We show that in the $S > 1 /2$ double exchange crystals with the antiferromagnetic $s-d$ exchange, a new type of magnetic strings appears, which possesses a magnetic moment. It is concentrat

M H Szymanska

The second part of this thesis is concerned with properties of excitons and modelling of excitonic lasing in quasi-one-dimensional quantum wires. I develop a very general numerical method of calculating the properties of wires with different shapes and materials. Using this method I study the properties of very wide range of T-shaped quantum wires.

Dietrich Stauffer

Suitable assumptions for the Gompertz mortality law take into account the break in the time development observed recently by Wilmoth et al. They show how a drastic reduction in the birth rate and improved living conditions lead to a drastic increase in the fraction of old people in the population, and how immigration of half a percent of the population per y

Roman Krahne, Tali Dadosh, Amir Yacoby, Hadas Shtrikman

Nano-size objects like metal clusters present an ideal system for the study of quantum phenomena and for constructing practical quantum devices. Integrating these small objects in a macroscopic circuit is, however, a difficult task. So far the nanoparticles have been contacted and addressed by highly sophisticated techniques which are not suitable for large

C. Sire, P. -H. Chavanis

We address the thermodynamics (equilibrium density profiles, phase diagram, instability analysis...) and the collapse of a self-gravitating gas of Brownian particles in D dimensions, in both canonical and microcanonical ensembles. In the canonical ensemble, we derive the analytic form of the density scaling profile which decays as f(x)=x^{-α}, with alpha=2.

Tomas Novotny

We consider a model for stationary electronic transport through a one-dimensional chain of two leads attached to a perturbed central region (quantum dot) in the regime where the theory proposed recently by Capek for a similar model of phonon transport predicts the striking phenomenon of a permanent current between the leads. This result based on a rigorous b

Hidefumi Akiyama, Loren N. Pfeiffer, Aron Pinczuk, Ken W. West

We demonstrate strong one dimensional (1-D) many-body interaction effects in photoluminescence (PL) in a GaAs single quantum wire of unprecedented optical quality, where 1-D electron plasma densities are controlled via electrical gating. We observed PL of 1-D charged excitons with large binding energy of 2.3 meV relative to the neutral excitons, and its evol

Y. Japha, Y. B. Band

The dynamics of a Bose-Einstein condensate (BEC) in a time-dependent harmonic trapping potential is determined for arbitrary variations of the position of the center of the trap and its frequencies. The dynamics of the BEC wavepacket is soliton-like. The motion of the center of the wavepacket, and the spatially and temporally dependent phase (which affects t

P. -H. Chavanis

We discuss the statistical mechanics of rotating self-gravitating systems by allowing properly for the conservation of angular momentum. We study analytically the case of slowly rotating isothermal spheres by expanding the solutions of the Boltzmann-Poisson equation in a series of Legendre polynomials, adapting the procedure introduced by Chandrasekhar (1933

C. Garcia-Gomez, E. Athanassoula, C. Barbera

We have compiled a new sample of galaxies with published catalogs of HII region coordinates. This sample, together with the former catalog of Garcia-Gomez and Athanassoula (1991) will form the basis for subsequent studies of the spiral structure in disc galaxies. In this paper we address the problem of the deprojection of the galaxy images. For this purpose

Orsola De Marco, Noam Soker

We construct a speculative scenario for the evolution of Wolf-Rayet central stars of planetary nebula. It is clear from the latest infra-red observations that a new perspective has to be adopted: the simultaneous presence of carbon- and oxygen-rich dust (double dust chemistry), while being a rare phenomenon for H-rich central stars, is found around the vast

Michael Nauenberg

The nonlinear stability domain of Lagrange&#39;s celebrated 1772 solution of a three-body problem is obtained numerically as a function of the masses of the bodies and the common eccentricity of their Keplerian orbits. This domain shows that this solution may be realized in extra-solar planetary systems similar to those that have been discovered recently wit

Kwang Sik Jeong, Taekoon Lee

A new method of estimating higher order perturbative coefficients is discussed. It exploits the rapid, asymptotic growth of perturbative coefficients and the information on the singularities in the complex Borel plane. A comparison with other methods is made in several Quantum Chromodynamics (QCD) expansions.

G. J. Gounaris, C. Le Mouël

We present a new formalism describing the neutralino physics in the context of the minimal supersymmetric model (MSSM), where CP violation induced by complex $M_1$ and $μ$ parameters is allowed. The formalism is based on the construction of neutralino projectors, and can be directly generalized to non-minimal SUSY models involving any number of neutralinos.

Shin&#39;ichi Nojiri, Sergei D. Odintsov

Thermodynamics of five-dimensional Schwarzschild Anti-de Sitter (SAdS) and SdS black holes in the particular model of higher derivative gravity is considered. The free energy, mass (thermodynamical energy) and entropy are evaluated. There exists the parameters region where BH entropy is zero or negative. The arguments are given that corresponding BH solution

Akihiro Kushino, Yoshitaka Ishisaki, Umeyo Morita, Noriko Y. Yamasaki

We studied the energy spectrum and the large-scale fluctuation of the X-ray background with the ASCA GIS based on the ASCA MSS and LSS observations. A total of 91 fields with Galactic latitude |b|>10 deg were selected with a sky coverage of 50 deg^2 and 4.2 Ms of exposure. For each field, sources brighter than \sim 2\times 10^{-13}\ergs (2-10 keV) were elimi

R. N. Faustov, A. P. Martynenko

The contribution of pseudoscalar pole diagrams to the hadronic light-by-light corrections of order alpha^3 E_F to the ground state hyperfine splitting in hydrogenic atom is calculated in the pseudoscalar pole terms approximation. The vector dominance model for the form factor of the transition of a pseudoscalar meson into two photons is used. With the accoun

XuBo Zou, K. Pahlke, W. Mathis

We propose a scheme to generate nonclassical states of a quantum system, which is composed of the one-dimensional trapped ion motion and a single cavity field mode. We show that two-mode SU(2) Schrödinger-cat states, entangled coherent states, two-mode squeezed vacuum states and their superposition can be generated. If the vibration mode and the cavity mode

Peter Schauenburg

We give a detailed comparison between the notion of a weak Hopf algebra (also called a quantum groupoid by Nikshych and Vainerman), and that of a $\times_R$-bialgebra due to Takeuchi (and also called a bialgebroid or quantum (semi)groupoid by Lu and Xu). A weak bialgebra is the same thing as a $\times_R$-bialgebra in which $R$ is Frobenius-separable. We exte

Manfred Einsiedler, Graham Everest, Thomas Ward

An approach to the calculation of local canonical morphic heights is described, motivated by the analogy between the classical height in Diophantine geometry and entropy in algebraic dynamics. We consider cases where the local morphic height is expressed as an integral average of the logarithmic distance to the closure of the periodic points of the underlyin

O. K. Sheinman

To a generic holomorphic vector bundle on an algebraic curve and an irreducible finite-dimensional representation of a semisimple Lie algebra, we assign a representation of the corresponding affine Krichever--Novikov algebra in the space of semi-infinite exterior forms. It is shown that equivalent pairs of data give rise to equivalent representations and vic

D. Chéniot, C. Eyral

In 1933, van Kampen described the fundamental groups of the complements of plane complex projective algebraic curves. Recently, Chéniot-Libgober proved an analogue of this result for higher homotopy groups of the complements of complex projective hypersurfaces with isolated singularities. Their description is in terms of some &#34;homotopical variation opera

Yan Doumerc

We use a matrix central-limit theorem which makes the Gaussian Unitary Ensemble appear as a limit of the Laguerre Unitary Ensemble together with an observation due to Johansson in order to derive new representations for the eigenvalues of GUE. For instance, it is possible to recover the celebrated equality in distribution between the maximal eigenvalue of GU

Manfred Einsiedler, Thomas Ward

The exact order of mixing for zero-dimensional algebraic dynamical systems is not entirely understood. Here non-Archimedean norms in function fields of positive characteristic are used to exhibit an asymptotic shape in non-mixing sequences for algebraic $Z^2$-actions. This gives a relationship between the order of mixing and the convex hull of the defining p

Graham Everest, Yash Puri, Thomas Ward

An existing dialogue between number theory and dynamical systems is advanced. A combinatorial device gives necessary and sufficient conditions for a sequence of non-negative integers to count the periodic points in a dynamical system. This is applied to study linear recurrence sequences which count periodic points. Instances where the $p$-parts of an integer

Barry Brent

We propose the existence of an infinite class of exact analogues of the 3x+1 conjecture for rational numbers with fixed denominators. For some other denominators, there are several attracting cycles, which exhibit scaling and covariance phenomena. We analyze these phenomena in terms of results of Bohm, Sontacchi and Lagarias.

Nathalie Wahl

Tillmann introduced two infinite loop space structures on the plus construction of the classifying space of the stable mapping class group, each with different computational advantages. The first one uses disjoint union on a suitable cobordism category, whereas the second uses an operad which extends the pair of pants multiplication (i.e. the double loop spa