September 2000 arXiv papers — page 23

S. N. Dorogovtsev, J. F. F. Mendes

Motivated by data on the evolution of the Internet and World Wide Web we consider scenarios of self-organization of the nonlinearly growing networks into free-scale structures. We find that the accelerating growth of the networks establishes their structure. For the growing networks with preferential linking and increasing density of links, two scenarios are

Pedro Pereyra

In this letter new, closed and compact analytic expressions for the evaluation of resonant energies, resonant bound-states, eigenvalues and eigenfunctions for both scattering and bounded $n$-cell systems are reported. It is shown that for (scattering and bounded) 1-D systems the eigenfunctions $Ψ_{μ,ν}(z)$ are simple and well defined functions of the Chebysh

Gus L. W. Hart, Alex Zunger

Boron arsenide, the typically-ignored member of the III-V arsenide series BAs-AlAs-GaAs-InAs is found to resemble silicon electronically: its Gamma conduction band minimum is p-like (Gamma_15), not s-like (Gamma_1c), it has an X_1c-like indirect band gap, and its bond charge is distributed almost equally on the two atoms in the unit cell, exhibiting nearly p

N. B. Wilding, A. D. Bruce

We describe a Monte Carlo procedure which allows sampling of the disjoint configuration spaces associated with crystalline and fluid phases, within a single simulation. The method utilises biased sampling techniques to enhance the probabilities of gateway states (in each phase) which are such that a global switch (to the other phase) can be implemented. Equi

M. Leadbeater, T. Winiecki, D. C. Samuels, C. F. Barenghi

By performing numerical simulations of superfluid vortex ring collisions we make direct quantitative measurements of the sound energy released due to vortex reconnections. We show that the energy radiated expressed in terms of the loss of vortex line length is a simple function of the reconnection angle. In addition, we study the temporal and spatial distrib

W. P. Orrick, B. G. Nickel, A. J. Guttmann, J. H. H. Perk

We report computations of the short-distance and the long-distance (scaling) contributions to the square-lattice Ising susceptibility in zero field close to T_c. Both computations rely on the use of nonlinear partial difference equations for the correlation functions. By summing the correlation functions, we give an algorithm of complexity O(N^6) for the det

Michele Cini, Gianluca Stefanucci

We introduce a local formalism to deal with the Hubbard model on a N times N square lattice (for even N) in terms of eigenstates of number operators, having well defined point symmetry. For U -> 0, the low lying shells of the kinetic energy are filled in the ground state. At half filling, using the 2N-2 one-body states of the partially occupied shell S_{hf},

G. Gomila, L. Reggiani, J. M. Rubi

We give a theoretical interpretation of the noise properties of Schottky barrier diodes based on the role played by the long range Coulomb interaction. We show that at low bias Schottky diodes display shot noise because the presence of the depletion layer makes negligible the effects of the Coulomb interaction on the current fluctuations. When the device pas

Henk W. Ch. Postma, Mark de Jonge, Zhen Yao, Cees Dekker

Using an atomic force microscope we have created nanotube junctions such as buckles and crossings within individual single-wall metallic carbon nanotubes connected to metallic electrodes. The electronic transport properties of these manipulated structures show that they form electronic tunnel junctions. The conductance shows power-law behavior as a function

Han-Oh Lee, Han-Yong Choi

The Korringa ratio, $\cal K$, obtained by taking an appropriate combination of the Knight shift and nuclear spin-lattice relaxation time, is calculated at finite temperature, $T$, in the three-dimensional electron gas model, including the electron-electron interaction, $U$, and non-magnetic impurity scatterings. $\cal K$ varies in a simple way with respect t

W. C. Barber, D. P. Belanger

The specific heat (Cm) and optical birefringence (Δn) for the magnetic percolation threshold system Fe(0.25)Zn(0.75)F2 are analyzed with the aid of Monte Carlo (MC) simulations. Both Δn and the magnetic energy (Um) are governed by a linear combination of near-neighbor spin-spin correlations, which we have determined for Δn using MC simulations modeled closel

R. Haslinger, Andrey V. Chubukov, Ar. Abanov

We study the spectral function $A_k (ω)$ and the optical conductivity $σ_1 (ω)$ for a system of fermions interacting with their collective spin fluctuations (the spin-fermion model), and apply the results to optimally doped cuprates in the normal state. We show that there is no qualitative distinction between hot and cold regions in the Brillouin zone - in b

F. C. Montenegro, D. P. Belanger, Z. Slanic, J. A. Fernandez-Baca

The highly diluted antiferromagnet Mn(0.35)Zn(0.65)F2 has been investigated by neutron scattering for H>0. A low-temperature (T<11K), low-field (H<1T) pseudophase transition boundary separates a partially antiferromagnetically ordered phase from the paramagnetic one. For 1<H<7T at low temperatures, a region of antiferromagnetic order is field induced but is

Xiaoguang Wang, Uwe Grimm, Michael Schreiber

We study aperiodic systems based on substitution rules by means of a transfer-matrix approach. In addition to the well-known trace map, we investigate the so-called `antitrace&#39; map, which is the corresponding map for the difference of the off-diagonal elements of the 2x2 transfer matrix. The antitrace maps are obtained for various binary, ternary and qua

J. S. Sa&#39; Martins, S. Cebrat

The concept of random deaths in a computational model for population dynamics is critically examined. We claim that it is just an artifact, albeit useful, of computational models to limit the size of the populations and has no biological foundation. Alternative implementations of random deaths strategies are discussed and compared.

James M. Schombert

There is tremendous scientific potential in a National Virtual Observatory, particularly for projects that need to mine large databases for rare or unusual objects. However, the NVO will also make an impact on any project, large or small, the requires a mixture of datasets to explore a wide range of astrophysical phenomenon. In this article I discuss the inf

J. J. Bock, G. Neugebauer, K. Matthews, B. T. Soifer

Mid-infrared observations of the central source of NGC 1068 have been obtained with a spatial resolution in the deconvolved image of 0.1&#34; (~ 7pc). The central source is extended by ~1&#34; in the north-south direction but appears unresolved in the east-west direction over most of its length. About two-thirds of its flux can be ascribed to a core structur

Timothy M. Heckman

In this contribution I summarize our current knowledge of the nature and significance of starburst-driven galactic superwinds. These flows are driven primarily by the kinetic energy supplied by supernovae. Superwinds are complex, multiphase phenomena requiring a panchromatic observational approach. They are ubiquitous in galaxies in which the global star-for

J. A. Sellwood, A. Kosowsky

The success of the Lambda-CDM model on large scales does not extend down to galaxy scales. We list a dozen problems of the dark matter hypothesis, some of which arise in specific models for the formation of structure in the universe, while others are generic and require fine tuning in any dark matter theory. Modifications to the theory, such as adding proper

A. M. Hopkins, A. J. Connolly, A. S. Szalay

We present an analysis of the star formation rate in galaxies between 0.7<z<1.8 using Near Infrared Camera and Multi-Object Spectrograph (NICMOS) grism spectral observations. We detect 163 galaxies in an area of ~4.4 square arcminutes, 37 of which show possible H-alpha emission. We extend the observed H-alpha luminosity function (LF) in this redshift range t

Ken D. Olum, J. J. Blanco-Pillado, Xavier Siemens

In about half of all near-cusp events in superconducting cosmic strings with chiral currents (and probably with general currents as well), the string intersects itself near the cusp. Intercommutation causes the conversion of the string near the cusp into a vorton (in the chiral case) with very high Lorentz boost. We demonstrate how to analyze the cusp shape

B. Hoeneisen

We develop a simple, fast and predictive model of the hierarchical formation of galaxies which is in quantitative agreement with observations. Comparing simulations with observations we place constraints on the density of the universe and on the power spectrum of density fluctuations.

L. M. Young

The distribution and kinematics of the molecular gas in elliptical galaxies give information on the origin and history of the gas and the rate of star formation activity in ellipticals. I describe some preliminary results of a survey which will more than double the number of elliptical galaxies with resolved molecular distributions.

L. M. Young, L. van Zee, R. C. Dohm-Palmer, K. Y. Lo

High spatial and spectral resolution observations of the atomic interstellar medium in nearby dwarf galaxies reveal evidence for warm and cold neutral gas, just like the phases in our own Galaxy. The cold or quiescent phase (about 20% of the HI in the galaxies studied, except for LGS 3) seems to be associated with star formation activity--- it may mark the r

David C. Fox, Ue-Li Pen

We investigate strong lensing of galaxies in the Hubble Deep Field by foreground groups and clusters of galaxies with masses from $10^{13}$ to $10^{15} \MSun$. Over this mass range, groups with the profile of Navarro, Frenk, & White (1995) are less efficient than singular isothermal spheres at producing multiple images of galaxies, by factors of $5 \times 10

Scott C. Chapman, Douglas Scott, Colin Borys, Gregory G. Fahlman

Recent submillimetre surveys have revealed a population of dusty, high redshift sources of great cosmological significance for understanding dust-enshrouded star formation in distant galaxies, and for determining the origin of the far-IR background. In this paper, we analyze nine rich cluster fields mapped at 850 and 450 microns with the SCUBA array on the J

D. Martinez-Delgado, A. Aparicio, M. A. Gomez-Flechoso

We present preliminary results of a long-term project to investigate the process of accretion and tidal disruption of dSph satellites in the Galactic halo and, in particular, to search for new tidal tails in a sample of nearby dSph satellites of the Milky Way. Here we present our finding of extra-tidal debris in the Ursa Minor dS ph and discuss the detection

M. E. Salvo, E. Cappellaro, P. A. Mazzali, S. Benetti

UBVRIJ photometry and optical spectra of the Type Ia SN 1996X obtained at ESO during a one-year-long observational campaign are presented, and supplemented by late time HST photometry. Spectroscopically, SN 1996X appears to be a `normal&#39; SN Ia. The apparent magnitude at maximum was B=13.24 +/- 0.02, and the colour B-V=0.00 +/- 0.03. The luminosity declin

A. B. Koptsevich, G. G. Pavlov, S. V. Zharikov, V. V. Sokolov

We present the results of the broad-band photometry of the nearby middle-aged radio pulsar PSR B0656+14 and its neighborhood obtained with the 6-meter telescope of the SAO RAS and with the Hubble Space Telescope. The broad-band spectral flux $F_ν$ of the pulsar decreases with increasing frequency in the near-IR range and increases with frequency in the near-

C. Adami, B. P. Holden, F. J. Castander, A. Mazure

In this paper, we present an analysis of the dynamics and segregation of galaxies in rich clusters from z~0.32 to z~0.48 taken from the CFHT Optical PDCS (COP) survey and from the CNOC survey (Carlberg et al. 1997). Our results from the COP survey are based upon the recent observational work of Adami et al. (2000) and Holden et al. (2000) and use new spectro

A. R. King, K. Schenker, U. Kolb, M. B. Davies

We show that the usual picture of supersoft X-ray binary evolution as driven by conservative thermal-timescale mass transfer cannot explain the short orbital periods of RX J0537.7-7034 (3.5 hr) and 1E 0035.4-7230 (4.1 hr). Non-conservative evolution may produce such periods, but requires very significant mass loss, and is highly constrained.

W. L. Lee, L. Z. Fang

We investigated the evolution of the primordial density perturbations produced by inflation with thermal dissipation. A full relativistic analysis on the evolution of initial perturbations from the warm inflation era to a radiation-dominated universe has been developed. The emphasis is on tracking the ratio between the adiabatic and the isocurvature mode of

Jelte de Jong, Konrad Kuijken, Mark Neeser

Recent results of microlensing surveys, show that 10-20% of the dark halo mass of the Milky Way consists of compact objects. The masses of these compact objects range from 0.1 to 1 solar mass. New theoretical cooling models for white dwarfs, and the detection of faint blue high proper motion objects, imply that ancient white dwarfs might make up part of this

A. Capetti, H. R. de Ruiter, R. Fanti, R. Morganti

A Hubble Space Telescope snapshot survey of the B2 sample of low luminosity radio galaxies has, at present, produced V and I images of 41 objects. Together with 16 images of B2 sources taken from the HST archive, there are now high resolution optical data for 57 % of the sample. All host galaxies are luminous ellipticals, except one which is a spiral galaxy,

Maarten Baes, Herwig Dejonghe

Disk galaxies contain a large amount of interstellar dust, which affects the projection of kinematic quantities. We investigate in detail the effects of dust extinction on the mean projected velocity and the projected velocity dispersion. We use our results to construct a general strategy to determine the dynamical structure of disk galaxies, with the aim to

G. Dudziak, D. Pequignot, A. A. Zijlstra, J. R. Walsh

Radio continuum observations at 1.4, 4.8 and 8.6 GHz of the two Planetary Nebulae (PNe) in the Sagittarius dwarf galaxy reveal the elongated shape of Wray 16-423 and the extreme compactness of He 2-436. He 2-436 is confirmed as subject to local dust extinction. Photoionization models for both PNe are obtained from two different codes, allowing theoretical un

Yves Revaz, Daniel Pfenniger

Two methods generating warped galaxies with N-body simulations are presented. One uses an external potential as a disturber while the other is based on material accretion. The results of both methods are compared. A particular attention is given on the shape of the line of node (LON).

Carlos Barcelo, Matt Visser

We consider the case of a generic braneworld geometry in the presence of one or more moduli fields (e.g., the dilaton) that vary throughout the bulk spacetime. Working in an arbitrary conformal frame, using the generalized junction conditions of gr-qc/0008008 and the Gauss--Codazzi equations, we derive the effective ``induced&#39;&#39; on-brane gravitational

F. T. Brandt, Ashok Das, J. Frenkel, K. Rao

We study the radiative corrections to the Chern-Simons mass term at two loops in 2+1 dimensional quantum electrodynamics at finite temperature. We show that, in contrast to the behavior at zero temperature, thermal effects lead to a non vanishing contribution at this order. Using this result, as well as the large gauge Ward identity for the leading parity vi

Rajat Kumar Pradhan, Sandeep K. Joshi

We study the quantization of a model proposed by Newton to explain centripetal force namely, that of a particle moving on a regular polygon. The exact eigenvalues and eigenfunctions are obtained. The quantum mechanics of a particle moving on a circle and in an infinite potential well are derived as limiting cases.

Wen-Fa Lu, Sang Koo You, Jino Bak, Chul Koo Kim

In this paper, a variational perturbation scheme for nonrelativistic many-Fermion systems is generalized to a Bosonic system. By calculating the free energy of an anharmonic oscillator model, we investigated this variational expansion scheme for its efficiency. Using the modified Feynman rules for the diagrams, we obtained the analytical expression of the fr

Timothy F. Havel, Yehuda Sharf, Lorenza Viola, David G. Cory

An extension of the product operator formalism of NMR is introduced, which uses the Hadamard matrix product to describe many simple spin 1/2 relaxation processes. The utility of this formalism is illustrated by deriving NMR gradient-diffusion experiments to simulate several decoherence models of interest in quantum information processing, along with their Li

Peter Borrmann, Heinrich Stamerjohanns, Eberhard R. Hilf, David Tomanek

In contrast to the experimentally widely used isentropic demagnetization process for cooling to ultra-low temperatures we examine a particular classical model system that does not cool, but rather heats up with isentropic demagnetization. This system consists of several magnetite particles in a colloidal suspension, and shows the uncommon behavior of disorde

Robert Ehrlich

An earlier prediction of a cosmic ray neutron line right at the energy of the knee of the cosmic ray spectrum was based on the speculation that the electron neutrino is a tachyon whose mass is reciprocally related to the energy of the knee, $E_k$. Given the large uncertainty in $E_k$, the values of ${m_ν}^2$ corresponding to it are consistent with values rec

L. Moriconi, G. S. Dias

We study (1+1)-dimensional turbulence in the framework of the Martin-Siggia-Rose field theory formalism. The analysis is focused on the asymptotic behaviour at the right tail of the probability distribution function (pdf) of velocity differences, where shock waves do not contribute. A BRS-preserving scheme of phase space reduction, based on the smoothness of

David M. Goldberg

In this paper, we apply the Perturbative Least Action Method to model the Local Group of galaxies for various Cosmological models. We show that though the galaxy masses are theoretically good discriminators of $Ω_M$ given some observed MW and M31 separation and radial velocity, current estimates of the masses are insufficient to make any cosmological claims.

M. Chevallier, D. Polarski

Friedmann-Robertson-Walker universes with a presently large fraction of the energy density stored in an $X$-component with $w_X<-1/3$, are considered. We find all the critical points of the system for constant equations of state in that range. We consider further several background quantities that can distinguish the models with different $w_X$ values. Using

Hui Hu, Dai-Jun Li, Jia-Lin Zhu, Jia-Jiong Xiong

The size effects of an exciton in a nano-ring are investigated theoretically by using an effective-mass Hamiltonian which can be separated in terms of the center-of-mass and relative coordinates. The binding energy and oscillator strength of the ground state are calculated for two different ring radii as a function of the ring width. The resulting linear opt

I. L. Buchbinder, V. D. Pershin

We discuss the problem of consistent description of higher spin massive fields coupled to external gravity. As an example we consider massive field of spin 2 in arbitrary gravitational field. Consistency requires the theory to have the same number of degrees of freedom as in flat spacetime and to describe causal propagation. By careful analysis of lagrangian

Jiri Hoogland, Dimitri Neumann

In this article we present a new approach to the numerical valuation of derivative securities. The method is based on our previous work where we formulated the theory of pricing in terms of tradables. The basic idea is to fit a finite difference scheme to exact solutions of the pricing PDE. This can be done in a very elegant way, due to the fact that in our

M. D. Reid

We suggest to test the premise of ``macroscopic local realism&#39;&#39; which is sufficient to derive Bell inequalities when measurements of photon number are only accurate to an uncertainty of order $n$ photons, where $n$ is macroscopic. Macroscopic local realism is only sufficient to imply, in the context of the original Einstein-Podolsky-Rosen argument, f

R. Kajimoto, H. Yoshizawa, Y. Tomioka, Y. Tokura

The melting process of the orbital order in Pr0.5Ca0.5MnO3 single crystal has been studied in detail as a function of temperature by neutron diffraction. It is demonstrated that a commensurate-incommensurate (C-IC) transition of the orbital ordering takes place in a bulk sample, being consistent with the electron diffraction studies. The lattice structure an

J. M. Diego, E. Martinez-Gonzalez, J. L. Sanz, L. Cayon

We have used recent X-ray and optical data in order to impose some constraints on the cosmology and cluster scaling relations. Generically two kind of hypotheses define our model. First we consider that the cluster population is well described by the standard Press-Schechter (PS) formalism, and second, these clusters are supposed to follow scaling relations

Nobuhito Maru, Norisuke Sakai, Yutaka Sakamura, Ryo Sugisaka

SUSY breaking without messenger fields is proposed. We assume that our world is on a wall and SUSY is broken only by the coexistence of another wall with some distance from our wall. The Nambu-Goldstone fermion is localized on the distant wall. Its overlap with the wave functions of physical fields on our wall gives the mass splitting of physical fields on o

C. Alexandrou, E. Follana, H. Panagopoulos, E. Vicari

We compute the ratio between the scale $Λ_L$ associated with a lattice formulation of QCD using the overlap-Dirac operator, and $Λ_{MS-bar}$. To this end, the one-loop relation between the lattice coupling $g_0$ and the coupling renormalized in the MS-bar scheme is calculated, using the lattice background field technique. We also compute the one-loop renorma

P. Valageas, A. Balbi, J. Silk

We present an analytic model, based on previous works which tackled the reionization history of the universe, which allows us to describe the generation of the secondary CMB anisotropies due to the kinetic SZ effect. We take into account the &#34;patchy pattern&#34; of reionization (HII bubbles), the cross-correlations of these ionized regions, the small-sca

J. A. Bellido, R. W. Clay, B. R. Dawson, M. Johnston-Hollitt

We report on an analysis of data from the southern hemisphere SUGAR cosmic ray detector. We confirm the existence of an excess of $10^{18}$eV cosmic rays from a direction close to the Galactic Centre, first reported by the AGASA group. We find that the signal is consistent with that from a point source, and we find no evidence for an excess of cosmic rays co

Kazuyuki Fujii

In this letter we make a brief review of some basic properties (the matrix elements, the trace, the Glauber formula) of coherent operators and study the corresponding ones for generalized coherent operators based on Lie algebra su(1,1). We also propose some problems.

Olindo Corradini, Zurab Kakushadze

We consider localization of gravity in smooth domain wall solutions of gravity coupled to a scalar field with a generic potential in the presence of the Gauss-Bonnet term. We discuss conditions on the scalar potential such that domain wall solutions are non-singular. We point out that the presence of the Gauss-Bonnet term does not allow flat solutions with l

Yasusada Nambu

We investigate the back reaction of cosmological perturbations on an inflationary universe using the renormalization-group method. The second-order zero mode solution which appears by the nonlinearity of the Einstein equation is regarded as a secular term of a perturbative expansion, we renormalized a constant of integration contained in the background solut

Nobuyoshi Ohta, Dan Tomino

We study D=3 field theories on the D3-branes stretched between two NS5-branes with NS B-field background. The theory is a noncommutative gauge theory. The mirror symmetry and S-duality of the theory are discussed. A new feature is that the mirror of the noncommutative gauge theory is not a field theory but an open string decoupled from the closed string. We

Y. S. Kim

If we reduce coherence in a given quantum system, the result is an increase in entropy. Does this necessarily convert this quantum system into a classical system? The answer to this question is No. The decrease of coherence means more uncertainty. This does not seem to make the system closer to classical system where there are no uncertainties. We examine th

Ernesto F. Galvao

I present a simple two-party quantum communication complexity protocol with higher success rate than the best possible classical protocol for the same task. The quantum protocol is shown to be equivalent to a quantum non-locality test, except that it is not necessary to close the locality loophole. I derive bounds for the detector efficiency and background c

Roberto Onofrio, Carlo Presilla

In quant-ph/9812017v2 M.B. Mensky reviewed our application of the restricted path integral approach to quantum measurements of energy. In this comment we point out that Mensky&#39;s assessment of our results is incorrect.

R. Klippert, H. C. Rosu

A formal SUSY QM procedure for any linear homogeneous second-order differential equation is briefly sketched up and applied to a simple exactly solvable case

Arindam Mitra

We present a perfectly secure cipher system based on the concept of fake bits which has never been used in either classical or quantum cryptography.

R. M. Santilli

We recall that hydrogen combustion does resolve the environmental problems of fossil fuels due to excessive emission of carcinogenic substances and carbon dioxide. However, hydrogen combustion implies the permanent removal from our atmosphere of directly usable oxygen, a serious environmental problem called oxygen depletion, since the combustion turns oxygen

Li-Shing Hou, Wei-Tou Ni

We use a rotatable torsion balance to perform an equivalence principle test on a magnetically shielded spin-polarized body of HoFe_{3}. With a rotation period of one hour, the period of possible signal is reduced from one solar day by 24 times, and hence the 1/f noise is greatly reduced. Our present experimental results gives a limit (0.25 +- 1.26) X 10^{-9}

Li-Shing Hou, Wei-Tou Ni, Yu-Chu M. Li

To test the cosmic spatial isotropy, we use a rotatable torsion balance carrying a transversely spin-polarized ferrimagnetic Dy_{6}Fe_{23} mass. With a rotation period of one hour, the period of anisotropy signal is reduced from one sidereal day by about 24 times, and hence the 1/f noise is greatly reduced. Our present experimental results constrain the cosm

D. E. Malov, A. S. Umar, D. J. Ernst, D. J. Dean

We develop and extend the dynamical string parton model. This model, which is based on the salient features of QCD, uses classical Nambu-Gotō strings with the endpoints identified as partons, an invariant string breaking model of the hadronization process, and interactions described as quark-quark interactions. In this work, the original model is extended to

W. Noerenberg, G. Papp, P. Rozmej

The diabatic approach to collective nuclear motion is reformulated in the local-density approximation in order to treat the normal modes of a spherical nuclear droplet analytically. In a first application the adiabatic isoscalar modes are studied and results for the eigenvalues of compressional (bulk) and pure surface modes are presented as function of densi

Boris Malomed, Andrei Vladimirov, Galina Khodova, Nikolay Rosanov

We introduce the simplest one-dimensional model of a dispersive optical medium with saturable dissipative nonlinearity and filtering (dispersive loss) which gives rise to stable solitary pulses (autosolitons). In the particular case when the dispersive loss is absent, the same model may also be interpreted as describing a stationary field in a planar optical

M. Brack, M. Sieber, S. M. Reimann

We discuss the localization of wavefunctions along planes containing the shortest periodic orbits in a three-dimensional billiard system with axial symmetry. This model mimicks the self-consistent mean field of a heavy nucleus at deformations that occur characteristically during the fission process [1,2]. Many actinide nuclei become unstable against left-rig

E. K. Sklyanin

The course of 5 lectures given at the seminar &#34;Integrable Systems: from Classical to Quantum&#34; (Universite de Montreal, Jul 26 -- Aug 6, 1999) contains a detailed comment on the recently discovered (Gaudin-Pasquier, 1992) connection between Baecklund transformations in the theory of classical integrable systems on one hand, and Baxter&#39;s Q-operator

Chikara Furusawa, Kunihiko Kaneko

Through extensive studies of dynamical system modeling cellular growth and reproduction, we find evidence that complexity arises in multicellular organisms naturally through evolution. Without any elaborate control mechanism, these systems can exhibit complex pattern formation with spontaneous cell differentiation. Such systems employ a `cooperative&#39; use

Chikara Furusawa, Kunihiko Kaneko

Based on extensive study of a dynamical systems model of the development of a cell society, a novel theory for stem cell differentiation and its regulation is proposed as the ``chaos hypothesis&#39;&#39;. Two fundamental features of stem cell systems - stochastic differentiation of stem cells and the robustness of a system due to regulation of this different

K. -H. Rehren

The relations and differences between various classification problems arising in the context of local two-dimensional conformal QFT, modular invariants, and subfactors are discussed. The extent to which locality implies modular invariance, is exhibited.

V. S. Vladimirov

Regularized adelic formulas for gamma and beta functions for arbitrary quasicharacters (either ramified or not) and in an arbitrary field of algebraic numbers are concretized as applied to one-class quadratic fields (and to the field of rational numbers). Applications to 4-tachyon tree string amplitudes, to the Veneziano (open strings) and Virasoro (closed s

Timo Seppalainen

We study aspects of the hydrodynamics of one-dimensional totally asymmetric K-exclusion, building on the hydrodynamic limit of Seppalainen (1999). We prove that the weak solution chosen by the particle system is the unique one with maximal current past any fixed location. A uniqueness result is needed because we can prove neither differentiability nor strict

Martin Olbrich

Let $Y=Γ\backslash H^n$ be a quotient of the hyperbolic space by the action of a discrete convex-cocompact group of isometries. We describe certain spaces of $Γ$-invariant currents on the sphere at infinity of $H^n$ with support on the limit set of $Γ$. These spaces are finite-dimensional. The main result identifies the cohomology of $Y$ with a quotient of s

Robin Chapman

Recently Zagier proved a remarkable q-series identity. We show that this identity can also be proved by modifying Franklin&#39;s classical proof of Euler&#39;s pentagonal number theorem.

Maria Laura Barberis

Let $g$ be a hyper-Hermitian metric on a simply connected hypercomplex four-manifold $M$. We show that when the isometry group $I(M,g)$ contains a subgroup acting simply transitively on $M$ by hypercomplex isometries then the metric $g$ is conformal to a hyper-Kähler metric. We describe explicitely the corresponding hyper-Kähler metrics and it follows that,

Olav Nygaard

We define the ($w^\ast$-) boundedness property and the ($w^\ast$-) surjectivity property for sets in normed spaces. We show that these properties are pairwise equivalent in complete normed spaces by characterizing them in terms of a category-like property called ($w^\ast$-) thickness. We give examples of interesting sets having or not having these properties

Victor Bovdi, A. L. Rosa

Let KG be a group algebra of a finite p-group G over a finite field K of characteristic p. We compute the order of the unitary subgroup of the group of units when G is either an extraspecial 2-group or the central product of such a group with a cyclic group of order 4 or G has an abelian subgroup A of index 2 and an element b such that b inverts each element

Victor Bovdi

Let $R$ be a ring with unity and $U(R)$ its group of units. Let $ΔU=\{a\in U(R)\mid [U(R):C_{U(R)}(a)]<\infty\}$ be the $FC$-radical of $U(R)$ and let $\nabla(R)=\{a\in R\mid [U(R):C_{U(R)}(a)]<\infty\}$ be the $FC$-subring of $R$. An infinite subgroup $H$ of $U(R)$ is said to be an $ω$-subgroup if the left annihilator of each nonzero Lie commmutator $[x,y]$

Ricardo Perez-Marco

We give a criterium of holomorphy for some type formal power series. This gives a stronger form of a Rothstein&#39;s type extension theorem for a particular ring of holomorphic functions.

Ricardo Perez-Marco

We study the linearization problem of germs of holomorphic diffeomorphisms with resonant linear part. The formal linearization requires in general an infinite number of algebraic relations to be satisfied by the coefficients of the power series defining the holomorphic germ. For a fixed germ, the linearizing mappings are not unique, but the existence of a fi

Ricardo Perez-Marco

We study generic holomorphic families of dynamical systems presenting problems of small divisors with fixed arithmetic. We prove that we have convergence for all parameter values or divergence everywhere except for an exceptional set in the potential theory sense. We illustrate this general principle in different problems of small divisors.

Ricardo Perez-Marco

We prove that Birkhoff normal form of hamiltonian flows at a non-resonant singular point with given quadratic part are always convergent or generically divergent. The same result is proved for the normalization mapping and any formal first integral.

Sergey Pekarsky, Anthony D. Blaom, Jerrold E. Marsden

When the phase space P of a Hamiltonian G-system (P, ω, G, J, H) has an almost Kahler structure a preferred connection, called abstract mechanical connection, can be defined by declaring horizontal spaces at each point to be metric orthogonal to the tangent to the group orbit. Explicit formulas for the corresponding connection one-form A are derived in terms

Jeffrey A. Harvey, Gregory Moore

We show that the relation between D-branes and noncommutative tachyons leads very naturally to the relation between D-branes and K-theory. We also discuss some relations between D-branes and K-homology, provide a noncommutative generalization of the ABS construction, and give a simple physical interpretation of Bott periodicity. In addition, a framework for

Konstantin G. Savvidy, George K. Savvidy

In this note we prove the complete stability of the classical fluctuation modes of the rotating ellipsoidal membrane. The analysis is carried out in the full SU(N) setting, with the conclusion that the fluctuation matrix has only positive eigenvalues. This proves that the solution will remain close to the original one for all time, under arbitrary infinitesi

Yuri Makeenko

This is a short review of the relation between the Reduced Models and Noncommutative Yang-Mills Theories (NCYM) based on the work done in collaboration with J. Ambjorn, J. Nishimura and R. Szabo. Contents: 1.Twisted Eguchi-Kawai model (TEK), 2.Mapping onto NCYM, 3.Morita equivalence, 4.Fundamental matter, 5.Wilson loops in NCYM, 6.D-brane interpretation. Tal

R. Vilela Mendes

Phenomenological evidence suggests the existence of non-trivial background fields in the QCD vacuum. On the other hand SU(3) gauge theory possessses three different classes of both non-generic and non-trivial strata that may be used as classical backgrounds. It is suggested that this three-fold multiplicity of non-trivial vacua may be related to the existenc

Bert Janssen, Patrick Meessen

We propose a Chern-Simons term for N coinciding non-BPS D-branes. Demanding full U(N) invariance and compatibility with T-duality, it is shown that it is necessary to introduce new interaction terms, through which the non-BPS D-branes couple to all p-form RR fields.

F. Assaoui, N. Benhamou, T. Lhallabi

The description of the two sets of (4,0) supersymmetric models that are related by non-abelian duality transformations is given. The (4,0) supersymmetric WZNW is constructed and the formulation of the (4,0) supersymmetric sigma model dual to (4,0) supersymmetric WZNW model in the sense of Poisson-Lie T-duality is described.

M. C. Gonzalez-Garcia, C. Peña-Garay

We discuss the status of the solutions of the solar neutrino problem in terms of oscillations of $ν_e$ into active or sterile neutrinos. We present the results of a global fit to the full data set corresponding to the latest data presented at the $ν$-2000 conference. We show the possible solutions in the full parameter space including both MSW and vacuum, as

Yu. S. Surovtsev, D. Krupa, M. Nagy

In the model-independent approach consisting in the immediate application to the analysis of experimental data of such general principles as analyticity and unitarity, a confirmation of the $σ$-meson at $\sim$ 665 MeV and an indication for the glueball nature of the $f_0(1500)$ state are obtained on the basis of a simultaneous description of the isoscalar s-

N. N. Nikolaev, W. Schäfer, G. Schwiete

We formulate the perturbative QCD approach to coherent diffractive dijet production in pion-nucleon and pion-nucleus collisions at high energy. For hard dijets the Pomeron splitting mechanism in which both helicity amplitudes are proportional to the unintegrated gluon structure function of the proton and the pion distribution amplitude is shown to dominate.

B. I. Ermolaev, M. Greco, S. I. Troyan

Infrared evolution equations for small-$x$ behaviour of the non-singlet structure functions $f_1^{NS}$ and $g_1^{NS}$ are obtained and solved in the next-to-leading approximation, to all orders in $α_s$, and including running $α_s$ effects. The intercepts of these structure functions, i.e. the exponents of the power-like small-$x$ behaviour, are calculated.