March 2000 arXiv papers — page 3

Le-Man Kuang, Zhong-Wen Ouyang

We present a new theoretical treatment of macroscopic quantum self-trapping (MQST) and quantum coherent atomic tunneling in a zero-temperature two-species Bose-Einstein condensate system in the presence of the nonlinear self-interaction of each species, the interspecies nonlinear interaction, and the Josephson-like tunneling interaction. It is shown that the

A. Keren, Y. J. Uemura, G. Luke, P. Mendels

We investigate the spin dynamics of SrCr$_{9p}$Ga$_{12-9p}$O$_{19}$ for p below and above the percolation threshold p_c using muon spin relaxation. Our major findings are: (I) At T->0 the relaxation rate is T independent and proportional to p^3, (II) the slowing down of spin fluctuation is activated with an energy U which is also a linear function of p^3 and

Ch. Haeussler, J. Oppenlaender, N. Schopohl

A theoretical study is presented on a number N of resistively shunted Josephson junctions connected in parallel as a disordered 1D array by superconducting wiring in such a manner that there are N-1 individual SQUID loops with arbitrary shape formed.

M. Hart, P. Jefferies, N. F. Johnson, P. M. Hui

We provide a theoretical description of the Minority Game in terms of crowd effects. The size of the fluctuations arising in the game is controlled by the interplay between crowds of like-minded agents and their anti-correlated partners (anticrowds). The theoretical results are in good agreement with the numerical simulations over the entire parameter range

Munetaka Sasaki, Koji Nemoto

A new dynamics more natural than that proposed by Bouchaud and Dean is introduced to the Generalized Random Energy Model, and the master equation for the dynamics is solved exactly to calculate the time correlation function. Although our results are very similar to those obtained by Bouchaud and Dean qualitatively, the exponents for power law relaxation are

W. Pan, T. Jungwirth, H. L. Stormer, D. C. Tsui

We have measured magnetotransport at half-filled high Landau levels in a quantum well with two occupied electric subbands. We find resistivities that are {\em isotropic} in perpendicular magnetic field but become strongly {\em anisotropic} at $ν$ = 9/2 and 11/2 on tilting the field. The anisotropy appears at an in-plane field, $B_{ip} \sim$ 2.5T, with the ea

Mauro Bologna, Constantino Tsallis, Paolo Grigolini

We consider the $d=1$ nonlinear Fokker-Planck-like equation with fractional derivatives $\frac{\partial}{\partial t}P(x,t)=D \frac{\partial^γ}{\partial x^γ}[P(x,t) ]^ν$. Exact time-dependent solutions are found for $ ν= \frac{2-γ}{1+ γ}$ ($-\infty<γ\leq 2$). By considering the long-distance {\it asymptotic} behavior of these solutions, a connection is establ

A. K. Rajagopal, Sumiyoshi Abe

Probability distributions defined on the half space are known to be quite different from those in the full space. Here, a nonextensive entropic treatment is presented for the half space in an analytic and self-consistent way. In this development, the ordinary first moment of the random variable X is divergent in contrast to the case of the full space. A gene

P. Kurlberg, Z. Rudnick

We study semi-classical limits of eigenfunctions of a quantized linear hyperbolic automorphism of the torus (&#34;cat map&#34;). For some values of Planck&#39;s constant, the spectrum of the quantized map has large degeneracies. Our first goal in this paper is to show that these degeneracies are coupled to the existence of quantum symmetries. There is a comm

Chris J. Willott, Steve Rawlings, Katherine M. Blundell, Mark Lacy

Low-frequency radio surveys are ideal for selecting orientation-independent samples of extragalactic sources because the sample members are selected by virtue of their isotropic steep-spectrum extended emission. We use the new 7C Redshift Survey along with the brighter 3CRR and 6C samples to investigate the fraction of objects with observed broad emission li

S. Corbel, R. P. Fender, A. K. Tzioumis, M. Nowak

We report the results of a long-term campaign of radio, soft- and hard- X-ray observations of the galactic black hole candidate GX 339-4. In the Low-Hard X-ray state the system displays a strong 3-way linear correlation between soft- and hard-X-rays and radio emission, implying a coupling between the Comptonising corona and a radio-emitting compact jet. In t

D. B. Cline, F. W. Stecker

Astronomy at the highest energies observed must be performed by studying neutrinos rather than photons because the universe is opaque to photons of these energies. By making observations of neutrinos with energies above 10 EeV one can deduce information about the distribution and cosmological history of cosmic rays which may have been accelerated to energies

Laura Covi

We have evaluated the observational constraints on the spectral index $n$, in the context of a $Λ$CDM model. For $n$ scale-independent, as predicted by most models of inflation, present data require $n\simeq 1.0 \pm 0.1$ at the 2-$σ$ level. We have also studied the two-parameter scale-dependent spectral index, predicted by running-mass inflation models. Pres

H. W. W. Spoon, J. Koornneef, A. F. M. Moorwood, D. Lutz

We have observed the central region of the nearby starburst galaxy NGC4945 with the mid-infrared spectrometers SWS and PHT-S aboard ISO. We do not find any evidence for the existence of the powerful AGN, inferred from hard X-ray observations. The upper limits on our AGN tracers [NeV] 14.32um & 24.32um and [NeVI] 7.65um imply an A(V)>160 towards the NLR, assu

C. P. Dullemond, R. Turolla

We present an algorithm for two-dimensional radiative transfer in axisymmetric, circumstellar media. The formal integration of the transfer equation is performed by a generalization of the short characteristics (SC) method to spherical coordinates. Accelerated Lambda Iteration (ALI) and Ng&#39;s algorithm are used to converge towards a solution. By taking a

Mirt Gramann, Gert H&#34;utsi

We investigate the properties of clusters of galaxies in the $Λ$CDM models with a steplike initial power spectrum. We examine the mass function, the peculiar velocities and the power spectrum of clusters in models with different values of the density parameter $Ω_0$, the normalized Hubble constant h and the spectral parameter p, which describes the shape of

R. Cornelisse, J. Heise, E. Kuulkers, F. Verbunt

A long flux enhancement, with an exponential decay time of 86 min, is detected in 4U 1735-44 with the BeppoSAX Wide Field Cameras. We argue that this is a type-I X-ray burst, making it the longest such burst ever observed. Current theories for thermonuclear bursts predict shorter and more frequent bursts for the observed persistent accretion rate.

A. V. Zasov, A. Y. Kniazev, S. A. Pustilnik, A. G. Pramsky

Among the galaxies which were included in the Atlas and Catalogue of Interacting galaxies by Vorontsov-Velyaminov (hereafter VV) as multiple systems (&#34;nests&#34;, &#34;chains&#34; and similarly looking systems), there are many objects, where the interaction is not evident. Some of them are single objects, including low-mass galaxies with active star form

A. V. Fedorova, D. V. Bisikalo, A. A. Boyarchuk, O. A. Kuznetsov

We suggest a new mechanism to account for the loss of angular momentum in binaries with non-conservative mass exchange. It is shown that in some cases the loss of matter can result in increase of the orbital angular momentum of a binary. If included into consideration in evolutionary calculations, this mechanism appreciably extends the range of mass ratios o

M. Mouhcine, A. Lancon

We present new modelling of the spectrophotometric properties of intermediate age stellar populations in the near-infrared (NIR). We take into account the evolutionary and spectroscopic properties of the Asymptotic Giant Branch (AGB) stars which dominate the integrated NIR emission of those populations. The predictions of spectrophotometric narrow-band molec

M. Sugizaki, K. Kinugasa, K. Matsuzaki, Y. Terada

A new pulsating X-ray source, AX J183220-0840, with a 1549.1-s period was discovered at R.A.= 18h32m20s and Dec.=-8d40&#39;30&#39;&#39; (J2000, uncertainty=0.6degree) during an ASCA observation on the Galactic plane. The source was observed two times, in 1997 and in 1999. A phase-averaged X-ray flux of 1.1E-11 ergs cm-2 s-1 and pulsation period of 1549.1+/-0

Abraham Loeb, Eli Waxman

The universe is filled with a diffuse and isotropic extragalactic background of gamma-ray radiation, containing roughly equal energy flux per decade in photon energy between 3 MeV-100 GeV. The origin of this background is one of the unsolved puzzles in cosmology. Less than a quarter of the gamma-ray flux can be attributed to unresolved discrete sources, but

A. Roberge, P. D. Feldman, A. M. Lagrange, A. Vidal-Madjar

High resolution FUV echelle spectra showing absorption features arising from CI and CO gas in the Beta Pictoris circumstellar (CS) disk were obtained on 1997 December 6 and 19 using the Space Telescope Imaging Spectrograph (STIS). An unsaturated spin-forbidden line of CI at 1613.376 A not previously seen in spectra of Beta Pictoris was detected, allowing for

B. V. Vasiliev

From a minimum of total energy of celestial bodies, their basic parameters are obtained. The steady-state values of the mass, radius, and temperature of stars and white dwarfs, as well as masses of pulsars are calculated. The luminosity and giromagnetic ratio of celestial bodies are estimated. All the obtained values are in a satisfactory agreement with obse

J. E. Williams, A. Griffin

We consider the damping of condensate collective modes at finite temperatures arising from lack of equilibrium between the condensate and the non-condensate atoms, an effect that is ignored in the usual discussion of the collisionless region. As a first approximation, we ignore the dynamics of the thermal cloud. Our calculations should be applicable to colle

Sergey Bravyi, Alexei Kitaev

We define a model of quantum computation with local fermionic modes (LFMs) -- sites which can be either empty or occupied by a fermion. With the standard correspondence between the Foch space of $m$ LFMs and the Hilbert space of $m$ qubits, simulation of one fermionic gate takes $O(m)$ qubit gates and vice versa. We show that using different encodings, the s

Christoph Hanhart, Daniel R. Phillips, Sanjay Reddy

Neutrino and axion production in neutron stars occurs mainly as bremsstrahlung from nucleon-nucleon (NN) scattering. The energy radiated via neutrinos or axions is typically very small compared to other scales in the two-nucleon system. The rate of emission of such &#34;soft&#34; radiation is directly related to the on-shell NN amplitude, and thereby to the

Takeo Kato

Soliton-pair nucleation rates Gamma = A exp(-B) are studied in highly-biased sine-Gordon systems with a local inhomogeneity for both a thermal activation regime and a quantum tunneling regime. It is found that the local inhomogeneity strongly affects the nucleation rates by modifying the bias-dependence of the exponent B. This change in the exponent B is exp

S. Martinez, F. Nicolas, F. Pennini, A. Plastino

The proper way of averaging is an important question with regards to Tsallis&#39; Thermostatistics. Three different procedures have been thus far employed in the pertinent literature. The third one, i.e., the Tsallis-Mendes-Plastino (TMP) normalization procedure, exhibits clear advantages with respect to earlier ones. In this work, we advance a distinct (fro

Huseyin Kaya, Hue Sun Chan

The experimental calorimetric two-state criterion requires the van&#39;t Hoff enthalpy $ΔH_{\rm vH}$ around the folding/unfolding transition midpoint to be equal or very close to the calorimetric enthalpy $ΔH_{\rm cal}$ of the entire transition. We use an analytical model with experimental parameters from chymotrypsin inhibitor 2 to elucidate the relationshi

Anders Johansen, Didier Sornette

The fracture of materials is a catastrophic phenomenon of considerable technological and scientific importance. Here, we analysed experiments designed for industrial applications in order to test the concept that, in heterogeneous materials such as fiber composites, rocks, concrete under compression and materials with large distributed residual stresses, rup

C. L. Pryke

A comparative study of simulated air shower longitudinal profiles is presented. An appropriate thinning level for the calculations is first determined empirically. High statistics results are then provided, over a wide energy range, (10^14.0 to 10^20.5 eV), for proton & iron primaries, using four combinations of the MOCCA & CORSIKA program frameworks, and th

J. L. Alonso, L. A. Fernandez, F. Guinea, V. Laliena

It is shown that the double exchange Hamiltonian, with weak antiferromagnetic interactions, has a rich variety of first order transitions between phases with different electronic densities and/or magnetizations. For band fillings in the range $0.3 \le x \le 0.5$, and at finite temperatures, a discontinuous transition between phases with similar electronic de

Hiroshi Shimahara

Quasi-low-dimensional type II superconductors in parallel magnetic fields are studied when singlet pairing interactions and relatively weak triplet pairing interactions coexist. Singlet and triplet components of order parameter are mixed at high fields, and at the same time an inhomogeneous superconducting state called a Fulde-Ferrell-Larkin-Ovchinnikov stat

A. Hebecker, C. Wetterich

We construct a time dependent adjustment mechanism for the cosmological &#34;constant&#34; which could be at work in a late Friedmann-Robertson-Walker universe dominated by quintessence and matter. It makes use of a Brans-Dicke field that couples to the evolving standard-model vacuum energy density. Our explicit model possesses a stable late-time solution wi

William R. B. Lionheart, Jari Kaipio, Christopher N. McLeod

There are a number of constraints which limit the current and voltages which can be applied on a multiple drive electrical imaging system. One obvious constraint is to limit the maximum Ohmic power dissipated in the body. Current patterns optimising distinguishability with respect to this constraint are singular functions of the difference of transconductanc

S. Bellucci, E. Ivanov, S. Krivonos

Based on the concept of the partial breaking of global supersymmetry (PBGS), we derive the worldvolume superfield equations of motion for $N=1, D=4$ supermembrane, as well as for the space-time filling D2- and D3-branes, from nonlinear realizations of the corresponding supersymmetries. We argue that it is of no need to take care of the relevant automorphism

P. M. Garnavich, S. Jha, M. A. Pahre, K. Z. Stanek

We present near-infrared and optical observations of the afterglow to the Gamma-Ray Burst (GRB) 991216 obtained with the F. L. Whipple Observatory 1.2-m telescope and the University of Hawaii 2.2-m telescope. The observations range from 15 hours to 3.8 days after the burst. The temporal behavior of the data is well described by a single power-law decay with

Hale Bradt, Alan Levine, Ronald Remillard, Donald A. Smith

We present a tabulation of 46 transient x-ray sources monitored with the All-Sky Monitor (ASM) on the Rossi X-ray Timing Explorer (RXTE). They fall into four broad categories: short (~d), intermediate, and long (>500 d) duration of outbursts, and long period binary systems that flare up at periastron (e.g., Be systems). The mixture of outburst/quiescent cycl

Gregor Veble, Marko Robnik, Junxian Liu

In this work we present the results of a numerical and semiclassical analysis of high lying states in a Hamiltonian system, whose classical mechanics is of a generic, mixed type, where the energy surface is split into regions of regular and chaotic motion. As predicted by the principle of uniform semiclassical condensation (PUSC), when the effective $\hbar$

J. C. Montero, C. A. de S. Pires, V. Pleitez

We consider the contributions to the neutrinoless double beta decays in a $SU(3)_L\otimes U(1)_N$ electroweak model. We show that for a range of the parameters in the model there are diagrams involving vector-vector-scalar and trilinear scalar couplings which can be potentially as contributing as the light massive Majorana neutrino exchange one. We use these

Ken Haste Andersen, Marie-Line Chabanol, Martin van Hecke

We introduce order parameter models for describing the dynamics of sand ripple patterns under oscillatory flow. A crucial ingredient of these models is the mass transport between adjacent ripples, which we obtain from detailed numerical simulations for a range of ripple sizes. Using this mass transport function, our models predict the existence of a stable b

Yoshimi Tanaka, Koji Fukao, Yoshihisa Miyamoto

To clarify effects of crack speed and cross-link density on fracture energy of acrylamide gels, we evaluated the roughness of the fracture surface and measured the fracture energy taking into account the roughness. The fracture energy increases linearly with crack speed $V$ in a fast crack speed region, and the increasing rate of fracture energy with $V$ dec

Juan Crisostomo, Ricardo Troncoso, Jorge Zanelli

Gravitation theories selected by requiring that they have a unique anti-de Sitter vacuum with a fixed cosmological constant are studied. For a given dimension d, the Lagrangians under consideration are labeled by an integer k=1,2,...,[(d-1)/2]. Black holes for each d and k are found and are used to rank these theories. A minimum possible size for a localized

Juergen Dietel

We reconsider energy calculations of the spin polarized $ν=1/2$ Chern-Simons theory. We show that one has to be careful in the definition of the Chern-Simons path integral in order to avoid an IR divergent magnetic ground state energy in RPA as in \cite{di1}. We correct the path integral and get a well behaved magnetic energy by considering the energy of the

Masud Chaichian, Archil B. Kobakhidze

We consider Randall-Sundrum model with localized gravity, replacing the extra compact space-like dimension by a time-like one. In this way the solution to the hierarchy problem can be reconciled with a correct cosmological expansion of the visible universe, just as a trivial result of the sign flip of cosmological constants in the bulk and on the 3-branes re

Ahmed Jellal, Haru-Tada Sato

The q-deformed super Virasoro algebra proposed by Chaichian and Presnajder is examined. Presented is the realizations by the FFZ algebra (the magnetic translation algebra) defined on a two-dimensional lattice with a supersymmetric Hamiltonian.

Jens Schneider, Hartmut Wallis

The superfluid fraction of an atomic cloud can be defined using the cloud&#39;s response to a rotation of the external potential, i.e. the moment of inertia. In this paper we derive analytical results for the moment of inertia of a small number of non-interacting Bosons using the canonical ensemble. The required symmetrized averages are obtained via a repres

Horacio E. Camblong, Luis N. Epele, Huner Fanchiotti, Carlos A. Garcia Canal

A thorough analysis is presented of the class of central fields of force that exhibit: (i) dimensional transmutation and (ii) rotational invariance. Using dimensional regularization, the two-dimensional delta-function potential and the $D$-dimensional inverse square potential are studied. In particular, the following features are analyzed: the existence of a

T. Kise, T. Ogasawara, M. Ashida, Y. Tomioka

Ultrafast spin dynamics in ferromagnetic half-metallic compound Sr_2FeMoO_6 is investigated by pump-probe measurements of magneto-optical Kerr effect. Half-metallic nature of this material gives rise to anomalous thermal insulation between spins and electrons, and allows us to pursue the spin dynamics from a few to several hundred picoseconds after the optic

M. Matsuda, M. Fujita, K. Yamada, R. J. Birgeneau

Neutron scattering experiments reveal that a diagonal spin modulation, which is a one-dimensional modulation rotated away by 45$^\circ$ from that in the superconducting phase, occurs universally across the insulating spin-glass phase in La$_{2-x}$Sr$_x$CuO$_4$ (0.02$\le x\le$0.055). This establishes an intimate relation between the magnetism and the transpor

Masamichi Ishihara

We study the effects of the expansion of the system and the friction on the parametric amplification of mesonic fields in high energy heavy ion collisions within the linear $σ$ model . The equation of motion which is similar to Mathieu equation is derived to describe the time development of classical fields in the last stage of a heavy ion collision after th

J. Oppenheim, B. Reznik, W. Unruh

We examine the measurability of the temporal ordering of two events, as well as event coincidences. In classical mechanics, a measurement of the order-of-arrival of two particles is shown to be equivalent to a measurement involving only one particle (in higher dimensions). In quantum mechanics, we find that diffraction effects introduce a minimum inaccuracy

I. L. Buchbinder, A. Yu. Petrov

We investigate the low-energy effective action in N=4 super Yang-Mills theory with gauge group SU(n) spontaneously broken down to its maximal torus. Using harmonic superspace technique we prove an absence of any three- and four-loop corrections to non-holomorphic effective potential depending on N=2 superfield strengths. A mechanism responsible for vanishing

Andris Ambainis, Leonard J. Schulman, Umesh Vazirani

We consider quantum computing in the k-qubit model where the starting state of a quantum computer consists of k qubits in a pure state and n-k qubits in a maximally mixed state. We ask the following question: is there a general method for simulating an arbitrary m-qubit pure state quantum computation by a quantum computation in the k-qubit model? We show tha

Donatella Cassettari, Björn Hessmo, Ron Folman, Thomas Maier

We have designed and experimentally studied a simple beam splitter for atoms guided on an Atom Chip, using a current carrying Y-shaped wire and a bias magnetic field. This beam splitter and other similar designs can be used to build atom optical elements on the mesoscopic scale, and integrate them in matterwave quantum circuits.

M. Durdevich, H. E. Makaruk, R. Owczarek

A generalization of the results of Rasetti and Zanardi concerning avoiding errors in quantum computers by using states preserved by evolution is presented. The concept of the dynamical symmetry is generalized from the level of classical Lie algebras and groups, to the level of a dynamical symmetry based on quantum Lie algebras and quantum groups (in the sens

Per K Rekdal, Bo-Sture K Skagerstam

Phase diagrams of the micromaser system are mapped out in terms of the physical parameters at hand like the atom cavity transit time, the atom-photon frequency detuning, the number of thermal photons and the probability for a pump atom to be in its excited state. Critical fluctuations are studied in terms of correlation measurements on atoms having passed th

Denis Crottet

Project of an undergraduate student in physics (4th year) about the concept of quantum computers (QC) and its social impact. After a thourough theoretical introduction (chap. 2), the recent debate about NMR-based QC is dealt with in detail (chap. 3). Chapter 4 comments on the figure of the number of articles published on the subject, showing the dramatic gro

D. T. Pope, P. D. Drummond, W. J. Munro

Intracavity and external third order correlations in the damped nondegenerate parametric oscillator are calculated for quantum mechanics and stochastic electrodynamics (SED), a semiclassical theory. The two theories yield greatly different results, with the correlations of quantum mechanics being cubic in the system&#39;s nonlinear coupling constant and thos

Danny Summers, Chunyu Ma

During major megnetic storms, enhanced flux of relativistic electrons in the inner magnetosphere have been observed to correleated with ULF waves. The enhancements can take place over a period of several hours. In order to account for such a rapid generation of relativistic electrons, we examine the mechanism of transit-time acceleration of electrons by low-

O. M. Ritter, F. C. Santos, A. C. Tort

A method of obtaining vector constants of motion for time-independent as well as time-dependent central fields is discussed. Some well-established results are rederived in this alternative way and new ones obtained.

Antonina N. Fedorova, Michael G. Zeitlin

We present applications of variational-wavelet approach to nonlinear (rational) rms envelope equations. We have the solution as a multiresolution (multiscales) expansion in the base of compactly supported wavelet basis. We give extension of our results to the cases of periodic beam motion and arbitrary variable coefficients. Also we consider more flexible va

Alex Kaivarainen

1. Role of inter-domain water clusters in large-scale dynamics of proteins; 2. Description of large-scale dynamics of proteins based on generalized Stokes-Einstein and Eyring-Polany equation; 3. Dynamic model of protein-ligand complexes formation; 4. The life-time of quasiparticles and frequencies of their excitation; 5. Mesoscopic mechanism of enzyme cataly

U. Leonhardt, P. Piwnicki

Slow light generated by Electromagnetically Induced Transparency is extremely susceptible with respect to Doppler detuning. Consequently, slow-light gyroscopes should have ultrahigh sensitivity.

Yasushi Nara

The baryon distribution is studied by using a parton cascade model which is based on pQCD incorporating hard partonic scattering and dynamical hadronization scheme. In order to study baryon distribution,baryonic cluster formation is newly implemented as well as hadronic higher resonance states from parton/beam cluster decay. The net baryon number and charged

A. Steiner, M. Prakash, J. M. Lattimer

The mixed phase of quarks and hadrons which might exist in the dense matter encountered in the varying conditions of temperature and trapped neutrino fraction in proto-neutron stars is studied. The extent that the mixed phase depends upon the thermodynamical parameters as well as on the stiffness of matter in the hadronic and quark phases is discussed. We sh

L. E. Marcucci, R. Schiavilla, M. Viviani, A. Kievsky

The astrophysical factor for the proton weak capture on 3He is calculated with correlated-hyperspherical-harmonics bound and continuum wave functions corresponding to a realistic Hamiltonian consisting of the Argonne v18 two-nucleon and Urbana-IX three-nucleon interactions. The nuclear weak charge and current operators have vector and axial-vector components

T. -Y. Saito, J. Haidenbauer

The contribution of a $ππ$-exchange three-body force to the three-nucleon binding energy is calculated in terms of a $πN$ amplitude. The latter is based on a meson-theoretical model of $πN$ interaction developed by the Jülich group. Similar to a previous study based on simple phenomenological $πN$ potentials a very small effect of the resulting three-body fo

V. E. Bunakov, I. B. Ivanov, R. B. Panin

The earlier suggested criterion of quantum chaoticity, borrowed from the nuclear compound resonance theory, is used in the analysis of the quantum diamagnetic Kepler problem (the spinless charged particle motion in the Coulomb and homogenious magnetic fields).

Marko Robnik, Luca Salasnich, Marko Vranicar

By using the WKB quantization we deduce an analytical formula for the energy splitting in a double--well potential which is the usual Landau formula with additional quantum corrections. Then we analyze the accuracy of our formula for the double square well potential, the inverted harmonic oscillator and the quartic potential.

Cristobal Lopez, Alberto Alvarez, Emilio Hernandez-Garcia

A technique to forecast spatiotemporal time series is presented. it uses a Proper Ortogonal or Karhunen-Loève Decomposition to encode large spatiotemporal data sets in a few time-series, and Genetic Algorithms to efficiently extract dynamical rules from the data. The method works very well for confined systems displaying spatiotemporal chaos, as exemplified

John F. McGowan

A system-level genetic code is a hypothetical genetic code that exclusively or preferentially codes systems of interacting coadapted parts. System-level genetic codes differ from part-level genetic codes in which each discrete part is coded independently. In general, a system-level genetic code requires coding discrete interacting parts such as organs or pro

L. Pastur, V. Vasilchuk

Normalized eigenvalue counting measure of the sum of two Hermitian (or real symmetric) matrices $A_{n}$ and $B_{n}$ rotated independently with respect to each other by the random unitary (or orthogonal) Haar distributed matrix $U_{n}$ (i.e. $A_{n}+U_{n}^{\ast}B_{n}U_{n}$) is studied in the limit of large matrix order $n$. Convergence in probability to a limi

Ariel O. Garcia, Roberto C. Trinchero

We consider the representations of Hopf algebras involved in some physical models, namely, factorizable S-matrix models (FSM&#39;s), one-dimensional quantum spin chains (QSC&#39;s) and statistical vertex models (SVM&#39;s). These physical representations have definite hermiticity assignments and lead to star structures on the corresponding Hopf algebras. It

David Miralles, Josep Manel Parra, Jayme Vaz

Given the real Clifford algebra of a quadratic space with a given signature, we define a new product in this structure such that it simulates the Clifford product of a quadratic space with another signature different from the original one. Among the possible applications of this new product, we use it in order to write the minkowskian Dirac equation over the

Jih-Hsin Cheng, Hung-Lin Chiu

We propose the study of some kind of monopole equations directly associated with a contact structure. Through a rudimentary analysis about the solutions, we show that a closed contact 3-manifold with positive Tanaka-Webster curvature and vanishing torsion must be either not symplectically semifillable or having torsion Euler class of the contact structure.

R. S. Laugesen, M. C. Pugh

We study numerically the phase space of the evolution equation h_t = -(h^n h_{xxx})_x - B (h^m h_x)_x . Here h(x,t) is nonnegative, n>0 and m is real, and the Bond number B is positive. We pursue three goals: to investigate the nonlinear stability of the positive periodic and constant steady states; to locate heteroclinic connecting orbits between these stea

R. S. Laugesen, M. C. Pugh

We study the phase space of the evolution equation h_t = -(f(h) h_{xxx})_x - (g(h) h_x)_x by means of a dissipated energy (a Liapunov function). Here h(x,t) is nonnegative, and at h=0 the coefficient functions f>0 and g can either degenerate to 0, or blow up to infinity, or tend to a nonzero constant. We first show all positive periodic steady states are &#3

Siddhartha Bhattacharya

We consider endomorphism actions of arbitrary discrete semigroups on a connected metrizable topological group G. We give necessary and sufficient conditions for expansiveness of such actions when G is a Lie group or a compact finite-dimensional group.

Alex Clark

We generalize Hagopian&#39;s theorem characterizing solenoids to higher dimensions by showing that any homogeneous continuum admitting a fiber bundle projection onto a torus with totally disconnected fibers admits a compatible abelian topological group structure. The higher dimensional exponent group is then introduced.

Norbert Riedel

For certain one-dimensional Schroedinger-type difference operators with a complex potential, a &#34;complete&#34; set of exponentially decaying eigenvectors is shown to exist. &#34;Completeness&#34; entails that the parameters involved are obtained through evaluation of analytic functions on a Riemann surface.

V. M. Gichev

Let $G$ be a semidirect product of a simply connected nilpotent Lie group and $\R$. For a left invariant control system on $G$ with a convex cone as a control domain, it is proved that the attainable sets coincides with a &#34;halfspace&#34; if the degree of contact of the with some special subspaces is sufficiently high.

D. Huybrechts

In general, the product of harmonic forms is not harmonic. We study the top exterior power of harmonic two-forms on compact Kaehler manifolds. Often, it is not harmonic. This phenomenon is related to the geometry of the manifold and to the existence of rational curves in particular. K3 surfaces and hyperkaehler manifolds are discussed in detail.

Nicolas Perrin

In their article [1], L. Gruson and M. Skiti have constructed a birationnal map from the variety $\I$ of mathematical instantons of degree 3 to the variety of nets of quadrics in $\pd$. They describe by this way two irreducible componants of the boundary of $\I$ associated to the divisor of nets which contain a two-plane degenerated quadric and the divisor o

Xiaoping Xu

We find two combinatorial identities on the theta series of the root lattices of the finite-dimensional simple Lie algebras of type $D_{4n}$ and the cosets in their integral duals, in terms of the well-known Essenstein series $E_4(z)$ and Ramanujan series $\Dlt_{24}(z)$. Using these two identities, we determine the theta series of certain infinite families o

Tomasz Brzezinski, S. Caenepeel, G. Militaru, Shenglin Zhu

We study when induction functors (and their adjoints) between categories of Doi-Hopf modules and, more generally, entwined modules are separable, resp. Frobenius. We present a unified approach, leading to new proofs of old results by the authors, as well as to some new ones. Also our methods provide a categorical explanation for the relationship between sepa

F. Andreev, D. Auckly, L. Kapitanski, A. G. Kelkar

This note describes two problems related to the digital implementation of control laws in the infinite dimensional family of matching control laws, namely state estimation and sampled data induced error. The entire family of control laws is written for an inverted pendulum cart. Numerical simulations which include sampled data and a state estimator are prese

D. Galetti, J. T. Lunardi, B. M. Pimentel, M. Ruzzi

q-Deformed harmonic oscillator algebra for real and root of unity values of the deformation parameter is discussed by using an extension of the number concept proposed by Gauss, namely the Q-numbers. A study of the reducibility of the Fock space representation which explores the properties of the Gauss polynomials is presented. When the deformation parameter

A. C. Tort, F. C. Santos

We evaluate the Casimir vacuum energy at finite temperature associated with the Maxwell field confined by a perfectly conducting rectangular cavity and show that an extended version of the temperature inversion symmetry is present in this system.

Diego Bellisai, Francesco Fucito, Alessandro Tanzini, Gabriele Travaglini

The results obtained by Seiberg and Witten for the low-energy Wilsonian effective actions of N=2 supersymmetric theories with gauge group SU(2) are in agreement with instanton computations carried out for winding numbers one and two. This suggests that the instanton saddle point saturates the non-perturbative contribution to the functional integral. A natura

José F. Cariñena, Arturo Ramos

Shape Invariant potentials in the sense of [Gendenshte\&#34;ın L.É., JETP Lett. 38, (1983) 356] which depend on more than two parameters are not know to date. In [Cooper F., Ginocchio J.N. and Khare A., Phys. Rev. {\bf 36 D}, (1987) 2458] was posed the problem of finding a class of Shape Invariant potentials which depend on n parameters transformed by transl

Paul Watts

We consider the derivatives which appear in the context of noncommutative string theory. First, we identify the correct derivations to use when the underlying structure of the theory is a quasitriangular Hopf algebra. Then we show that this is a specific case of a more general structure utilising the Drinfel&#39;d twist. We go on to present reasons as to why

Mayumi Aoki, Noriyuki Oshimo

A new supersymmetric standard model based on N=1 supergravity is constructed, aiming at natural explanation for the proton stability without invoking an ad hoc discrete symmetry through R parity. The proton is protected from decay by an extra U(1) gauge symmetry. Particle contents are necessarily increased to be free from anomalies, making it possible to inc

Maxim Yu. Khlopov, Sergei G. Rubin, Alexander S. Sakharov

We discuss the evolution of U(1) symmetric scalar field at the inflation epoch with a pseudo Nambu-Goldstone tilt revealing after the end of exponential expansion of the Universe. The U(1) symmetry is supposed to be associated with baryon charge. It is shown that quantum fluctuations lead in natural way to baryon dominated Universe with antibaryon excess reg

X. Calmet

We compute CP asymmetries of one-particle inclusive B(s) --> D(s) X decay rates. We find that the weak angle gamma could in principle be extracted from these asymmetries although they are very small. Taking the decay width difference into account, we find that the time integrated CP asymmetries are of the order A=1.4 10^(-4) sin(gamma). Some large uncertaint

Mariusz Sadzikowski, Wojciech Broniowski

We analyze the phase diagram in effective chiral quark models (the Nambu-Jona-Lasinio model, the sigma-model with quarks) and show that at the mean-field level a phase with a periodically-modulated chiral fields separates the usual phases with broken and restored chiral symmetry. A possible signal of such a phase is the production of multipion jets travellin

Anna Kalliomaki, Jukka Maalampi

The most stringent constraint on the so-called effective electron neutrino mass from the present neutrinoless double beta decay experiments is |M_{ee}| < 0.2 eV, while the planned next generation experiment GENIUS is anticipated to reach a considerably more stringent limit |M_{ee}|< 0.001 eV. We investigate the constraints these bounds set on the neutrino ma

Michail P. Rekalo, Egle Tomasi-Gustafsson, Jacques Arvieux

A general analysis of polarization phenomena for coherent meson electroproduction on deuterons, $e+ d\to e+ d +P^0$, where $P^0$ is a pseudoscalar $π^0$ or $η$-meson, is presented. The spin structure of the electromagnetic current for $P^0$-production at threshold is parametrized in terms of specific (inelastic) threshold electromagnetic form factors which d

R. Foot, S. N. Gninenko

We suggest that the discrepant lifetime measurements of ortho-positronium can be explained by ortho-positronium oscillations into mirror ortho-positronium. This explanation can be tested in future vacuum experiments.