September 2002 arXiv papers — page 20

Cristian Micheletti, Fabio Cecconi, Alessandro Flammini, Amos Maritan

An exactly solvable model based on the topology of a protein native state is applied to identify bottlenecks and key-sites for the folding of HIV-1 Protease. The predicted sites are found to correlate well with clinical data on resistance to FDA-approved drugs. It has been observed that the effects of drug therapy are to induce multiple mutations on the prot

J. Marro, J. M. Cortes, Pablo I. Hurtado

We comment on some recent, yet unpublished results concerning instabilities in complex systems and their applications. In particular, we briefly describe main observations during extensive computer simulations of two lattice nonequilibrium models. One exhibits robust and efficient processes of pattern recognition under synaptic coherent activity; the second

Jordi Marcos, Eduard Vives, Lluis Manosa, Mehmet Acet

Measurements of magnetic hysteresis loops in Cu-Al-Mn alloys of different Mn content at low temperatures are presented. The loops are smooth and continuous above a certain temperature, but exhibit a magnetization discontinuity below that temperature. Scaling analysis suggest that this system displays a disorder induced phase transition line. Measurements all

A. Siber, H. Buljan

We calculate the energy-band structure of a He atom trapped within the interstitial channel between close-packed nanotubes within a bundle and its influence on the specific heat of the adsorbed gas. A robust prediction of our calculations is that the contribution of the low-density adsorbed gas to the specific heat of the nanotube material shows pronounced n

X. S. Chen, V. Dohm

We present the results of a one-loop calculation of the effect of a van der Waals type interaction potential $\sim | {\bf x} |^{-d-σ}$ on the critical Casimir force and specific heat of confined $^4$He near the superfluid transition. We consider a $^4$He film of thickness $L$. In the region $L \gtrsim ξ$ (correlation length) we find that the van der Waals in

Palash Das, Jayanta K. Bhattacharjee

We arrange the loopwise perturbation theory for the critical viscosity exponent $x_η$, which happens to be very small, as a power series in $x_η$ itself and argue that the effect of loops beyond two is negligible. We claim that the critical viscosity exponent should be very closely approximated by $x_η=\frac{8}{15 π^2}(1+\frac{8}{3 π^2})\simeq 0.0685$.

Alexander N. Gorban, Iliya V. Karlin, Hans Christian Ottinger

There exists only one generalization of the classical Boltzmann-Gibbs-Shannon entropy functional to a one-parametric family of additive entropy functionals. We find analytical solution to the corresponding extension of the classical ensembles, and discuss in some detail the example of the deformation of the uncorrelated state.

Degang Zhang, C. S. Ting

Motivated by the recent scanning tunneling microscopy (STM) experiment [J. E. Hoffman, {\it et al.}, Science {\bf 297}, 1148 (2002)], we investigate the energy-dependent modulation induced by a weak and extended defect in a d-wave superconductor. The Fourier component of the local density of states (LDOS) is calculated up to the first order in the defect par

Ling Miao, Michael A. Lomholt, Jesper Kleis

In this paper, the dynamics of spontaneous shape fluctuations of a single, giant quasi-spherical vesicle formed of a single lipid species is revisited theoretically. A coherent physical theory for the dynamics is developed based on a number of fundamental principles and considerations and a systematic formulation of the theory is also established. From the s

D. Vion, A. Aassime, A. Cottet, P. Joyez

We present a superconducting tunnel junction circuit which behaves as a controllable atom, and whose ground and first excited state form an effective spin 1/2. By applying microwave pulses, we have performed on this circuit experiments demonstrating the controlled manipulation of the spin : Rabi precession, Ramsey interferences, and spin echoes.

Pablo I. Hurtado, J. Marro, E. V. Albano

We studied phase separation in a particle interacting system under a large drive along x. We here identify the basic growth mechanisms, and demonstrate time self-similarity, finite-size scaling, as well as other interesting features of both the structure factor and the scaling function. We also show that, at late t in two dimensions, there is a unique t-depe

L. Ravagnan, F. Siviero, C. Lenardi, P. Piseri

Nanostructured carbon films produced by supersonic cluster beam deposition have been studied by in situ Raman spectroscopy. Raman spectra show the formation of a sp2 solid with a very large fraction of sp-coordinated carbyne species showing a long-term stability under ultra high vacuum. Distinct Raman contribution from polyyne and cumulene species have been

C. Hoffmann, F. Lefloch, M. Sanquer

We studied electronic relaxation in long diffusive superconductor / normal metal / superconductor (S/N/S) junctions by means of current noise and transport measurements down to very low temperature (100mK). Samples with normal metal lengths of 4, 10 and 60 micrometer have been investigated. In all samples the shot noise increases very rapidly with the voltag

Ferenc Kun, Raul Cruz Hidalgo, Hans J. Herrmann, Karoly F. Pal

We study the creep rupture of fiber composites in the framework of fiber bundle models. Two novel fiber bundle models are introduced based on different microscopic mechanisms responsible for the macroscopic creep behavior. Analytical and numerical calculations show that above a critical load the deformation of the creeping system monotonically increases in t

J. Oitmaa, W. Zheng

Strong-coupling expansions, to order $(t/J)^8$, are derived for the Kondo lattice model of strongly correlated electrons, in 1-, 2- and 3- dimensions at arbitrary temperature. Results are presented for the specific heat, and spin and charge susceptibilities.

Ph. Bronlet, M. Ausloos

We have translated fractional Brownian motion (FBM) signals into a text based on two ''letters'', as if the signal fluctuations correspond to a constant stepsize random walk. We have applied the Zipf method to extract the $ζ'$ exponent relating the word frequency and its rank on a log-log plot. We have studied the variation of the Zipf ex

W. Zheng, J. Oitmaa

We present new results for the Kondo lattice model of strongly correlated electrons, in 1-, 2-, and 3-dimensions, obtained from high-order linked-cluster series expansions. Results are given for varies ground state properties at half-filling, and for spin and charge excitations. The existence and nature of the predicted quantum phase transition are explored.

F. A. B. F. de Moura, M. D. Coutinho-Filho, E. P. Raposo, M. L. Lyra

We study the nature of collective excitations in harmonic chains with masses exhibiting long-range correlated disorder with power spectrum proportional to $1/k^α$, where $k$ is the wave-vector of the modulations on the random masses landscape. Using a transfer matrix method and exact diagonalization, we compute the localization length and participation ratio

Mahesh Chandran

This report discusses the implementation of two parallel algorithms on a distributed memory system for studying vortex dynamics in type-II superconductors. These algorithms are the same as that implemented for classical molecular dynamics simulation with short-range forces (Plimpton, J. Comp. Phys. Vol.117, 1 (1995)). The run time for parallel algorithm is t

S. Wolf

The influence of a dust grain mixture consisting of spherical dust grains with different radii and/or chemical composition on the resulting temperature structure and spectral energy distribution of a circumstellar shell is investigated. The comparison with the results based on an approximation of dust grain parameters representing the mean optical properties

Karen T. Lewis, David N. Burrows, John P. Hughes, Patrick O. Slane

We report on the results from a Chandra ACIS observation of the young, compact, supernova remnant N103B. The unprecedented spatial resolution of Chandra reveals sub-arcsecond structure, both in the brightness and in spectral variations. Underlying these small-scale variations is a surprisingly simple radial structure in the equivalent widths of the strong Si

Neal Katz, Dusan Keres, Romeel Dave, David H. Weinberg

Not the way one might have thought. In hydrodynamic simulations of galaxy formation, some gas follows the traditionally envisioned route, shock heating to the halo virial temperature before cooling to the much lower temperature of the neutral ISM. But most gas enters galaxies without ever heating close to the virial temperature, gaining thermal energy from w

N. Panagia, M. Stiavelli, H. C. Ferguson, H. S. Stockman

We present the first results of a study of the expected properties of the first stellar generations in the Universe. In particular, we consider and discuss a series of properties that, on the basis of the emission from associated HII regions, permit one to discern {\it bona fide} primeval stellar generations from the ones formed after pollution from supernov

G. D. Schmidt, P. S. Smith, C. B. Foltz, D. C. Hines

An infrared-selected, narrow-line QSO has been found to exhibit an extraordinarily broad Halpha emission line in polarized light. Both the extreme width (35,000 km/sec full-width at zero intensity) and 3,000 km/sec redshift of the line centroid with respect to the systemic velocity suggest emission in a deep gravitational potential. An extremely red polarize

Robert W. Bass

In a planetary or satellite system, idealized as n small bodies in initially coplanar, concentric orbits around a large central body, obeying Newtonian point-particle mechanics, resonant perturbations will cause dynamical evolution of the orbital radii except under highly specific mutual relationships, here derived analytically apparently for the first time.

Ray Jayawardhana, Subhanjoy Mohanty, Gibor Basri

We present high-resolution optical spectra of 15 objects near or below the sub-stellar limit in the Upper Scorpius and $ρ$ Ophiuchus star-forming regions. These spectra, obtained with the HIRES instrument on the Keck I telescope, are used to investigate disk accretion, rotation and activity in young very low mass objects. We report the detection of a broad,

Maqbool Ahmed, Scott Dodelson, Patrick B. Greene, Rafael Sorkin

A variety of observations indicate that the universe is dominated by dark energy with negative pressure, one possibility for which is a cosmological constant. If the dark energy is a cosmological constant, a fundamental question is: Why has it become relevant at so late an epoch, making today the only time in the history of the universe at which the cosmolog

Marc Kamionkowski

Recent results from cosmic microwave background (CMB) experiments verify several of the predictions of inflation, while ruling out a number of alternative structure-formation scenarios. Given the successes of the theory, the obvious next step is to press ahead and test inflation to the edge of all our current and forthcoming observational abilities. Accordin

M. Jura

We find that the infrared excess around HD 233517, a first ascent red giant, can be naturally explained if the star possesses an orbiting, flared dusty disk. We estimate that the outer radius of this disk is 45 AU and that the total mass within the disk is about 0.01 the mass of the Sun. We speculate that this disk is the result of the engulfment of a low ma

Philippe B. Marty, Jean-Paul Kneib, Rachida Sadat, Harald Ebeling

In this paper, a review is given of methods useful for XMM-Newton EPIC data analysis of extended sources, along with some applications to a bright massive cluster of galaxies at z=0.2, Abell 209. This may constitute an introduction to that kind of advanced analysis, complementing cookbooks that can be found over the internet, the XMM-Newton EPIC calibration

S. V. Bogovalov, D. V. Khangoulian

The formation of the toroidal and jet-like structures in the central part of the Crab Nebula is explained in the framework of Kennel & Coroniti theory. The only new element introduced by us in this theory is the initial anisotropy of the energy flux in the wind. We estimate the X-ray surface brightness of the Crab Nebula from the region of interaction of thi

Roberto P. Mignani, Richard N. Manchester, George G. Pavlov

We present the results of first deep optical observations of the field of the old ($\sim 10^8$ yr), nearby, isolated pulsar J0108-1431, in an attempt to detect its optical counterpart. The observations were performed using the FORS1 instrument at the focus of the European Southern Observatory Antu Telescope of the VLT. Observations with the Australia Telesco

F. Combes, S. Leon

We present CO(1-0) and CO(2-1) maps of the Seyfert galaxy NGC 5728. Although a stellar nuclear bar structure is clearly identified in the near-infrared images in the central 10", inside the ring identified as the ILR of the primary bar, there is no nuclear bar structure in the molecular gas. Instead, the CO emission reveals an elongated structure, 15&#34

F. Combes, S. Garcia-Burillo, F. Boone, L. K. Hunt

We present CO(1-0) and CO(2-1) maps of the Seyfert galaxy NGC 7217, obtained with the IRAM interferometer, at 3" and 1.5" resolution respectively. The nuclear ring (at r=12"=0.8kpc) is predominant in the CO maps, with a remarkable surface density gradient between the depleted region inside the ring and the inner border of the ring. The CO nuclear

Kevin A. Pimbblet

The model of the Big Bang is an integral part of the national curriculum for England. Previous work (e.g. Baxter 1989) has shown that pupils often come into education with many and varied prior misconceptions emanating from both internal and external sources. Whilst virtually all of these misconceptions can be remedied, there will remain (by its very nature)

Remo J. Ruffini

The idea that the vacuum polarization process occurring during gravitational collapse to a black hole endowed with electromagnetic structure (EMBH) could be the origin of gamma ray bursts (GRBs) is further developed. EMBHs in the range 3.2 -- 10$^6$ solar masses are considered. The formation of such an EMBH, the extraction of its mass-energy by reversible tr

Tommy Wiklind, Danielle Alloin

With today's millimeter and submillimeter instruments observers use gravitational lensing mostly as a tool to boost the sensitivity when observing distant objects. This is evident through the dominance of gravitationally lensed objects among those detected in CO rotational lines at z>1. It is also evident in the use of lensing magnification by galaxy clu

A. M. Soltan, M. J. Freyberg, G. Hasinger

The X-ray background intensity around Lick count galaxies and rich clusters of galaxies is investigated in three ROSAT energy bands. It is found that the X-ray enhancements surrounding concentrations of galaxies exhibit significantly softer spectrum than the standard cluster emission and the average extragalactic background. The diffuse soft emission accompa

Ulrich Hopp, Laura Greggio

Due to their star formation history (SFH), the stellar population in Dwarf Galaxies (DG) is likely to have a metallicity spread which is best traced by the morphology of the Red Giant Branch (RGB). We probe here a purely empirical approach aimed at estimating average metallicity (Z) and Z spread by comparing the Color-Magnitude Diagrams (CMD) of galactic Glo

H. Schild, P. A. Crowther, J. B. Abbott, W. Schmutz

We have detected 58 Wolf-Rayet candidates in the central region of the nearby spiral galaxy NGC 300, based on deep VLT-FORS2 narrow-band imaging. Our survey is close to complete except for heavily reddened WR stars. Of the objects in our list, 16 stars were already spectroscopically confirmed as WR stars by Schild & Testor and Breysacher et al., to which 4 s

Panayotis Boumis, Fotis Mavromatakis, Euthimios V. Paleologou, Werner Becker

Deep Halpha+[N II] CCD images have been obtained in the area of the Pegasus Constellation. The resulting mosaic covers an extent of ~7.5 degr x ~8.5 degr and filamentary and diffuse emission is discovered. Several long filaments (up to ~1 degr) are found within the field, while diffuse emission is present mainly in the central and northern areas. The filamen

Chris Churchill, Chuck Steidel

Comparisons of the kinematics of Mg II absorbing gas and the stellar rotation curves in 0.5 < z < 1.0 spiral galaxies suggests that, at least in some cases, the extended gaseous envelopes may be dynamically coupled to the stellar matter. A strong correlation exists between the overall kinematic spread of Mg II absorbing gas and C IV absorption strength, and

D. M. Smith, W. A. Heindl, J. H. Swank

Five years of Rossi X-ray Timing Explorer (RXTE) observations of the Galactic black-hole candidates 1E 1740.7-2942 and GRS 1758-258 show a periodic modulation with amplitude 3-4% in each source at 12.73 +/- 0.05 dy and 18.45 +/- 0.10 dy, respectively. We interpret the modulations as orbital, suggesting that the objects have red-giant companions. Combining th

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

The recent discovery, based on a search of public OGLE data, of Be star candidates in the Small Magellanic Cloud showing spectacular photometric variations (Mennickent et al. 2002), has motivated further analysis of their light curves. Here we report the results of a statistical study of the light curves of Type-1, Type-2 and Type-3 stars. Type-3 stars show

P. Berczik, G. Hensler, Ch. Theis, R. Spurzem

We present our recently developed 3-dimensional chemodynamical code for galaxy evolution. It follows the evolution of all components of a galaxy such as dark matter, stars, molecular clouds and diffuse interstellar matter (ISM). Dark matter and stars are treated as collisionless $N$-body systems. The ISM is numerically described by a smoothed particle hydrod

David T. Gay

We study neighborhoods of configurations of symplectic surfaces in symplectic 4-manifolds. We show that suitably `positive&#39; configurations have neighborhoods with concave boundaries and we explicitly describe open book decompositions of the boundaries supporting the associated negative contact structures. This is used to prove symplectic nonfillability f

Peter Kleban, Don Zagier

We examine crossing probabilities and free energies for conformally invariant critical 2-D systems in rectangular geometries, derived via conformal field theory and Stochastic Löwner Evolution methods. These quantities are shown to exhibit interesting modular behavior, although the physical meaning of modular transformations in this context is not clear. We

Daniel Thomas, Claudia Maraston, Ralf Bender

We provide the whole set of Lick indices from CN1 to TiO2 of Simple Stellar Population models with, for the first time, variable element abundance ratios, [alpha/Fe]=0.0, 0.3, 0.5, [alpha/Ca]=-0.1, 0.0, 0.2, 0.5, and [alpha/N]=-0.5, 0.0. The models cover ages between 1 and 15 Gyr, metallicities between 1/200 and 3.5 solar. Our models are free from the intrin

M. C. B. Abdalla, M. A. De Andrade, M. A. Santos, I. V. Vancea

The Dirac eigenvalues form a subset of observables of the Euclidean gravity. The symplectic two-form in the covariant phase space could be expressed, in principle, in terms of the Dirac eigenvalues. We discuss the existence of the formal solution of the equations defining the components of the symplectic form in this framework.

L. Grandchamp, R. Rapp

The production of charmonia in ultrarelativistic heavy-ion collisions is investigated including two sources. These are a primordial contribution coupled with various phases of dissociation, and a statistical coalescence of $c$ and $\bar{c}$ quarks at the hadronization phase transition. Within a schematic fireball evolution, SPS data on $J/Ψ$ production can b

Joel E. Moore

It is known that the localization length scaling of noninteracting electrons near the quantum Hall plateau transition can be described in a theory of the bosonic density operators, with no reference to the underlying fermions. The resulting ``Liouvillian&#39;&#39; theory has a $U(1|1)$ global supersymmetry as well as a hierarchy of geometric conservation law

F. O. Durães, F. S. Navarra, G. Wilk

We have calculated the mass distribution ($dσ/dM_X$) as observed by UA8 Collaboration in the inclusive reaction $p \bar p \to p X \bar p$ at $\sqrt s = 630 GeV$, using the Interacting Gluon Model (IGM) with Double Pomeron Exchange included. The only new parameter is the $IP IP$ cross section, which we can extract from fitting experimental data. We compare ou

Cristina Chiappini, Agostino Renda, Francesca Matteucci

In this work we present the predictions of the ``two-infall model&#39;&#39; concerning the evolution of D, 3He and 4He in the solar vicinity, as well as their distribution along the Galactic disk. Our results show that, when adopting detailed yields taking into account the extra-mixing process in low and intermediate mass stars, the problem of the overproduc

I. Bena, C. Van den Broeck, R. Kawai, Katja Lindenberg

Dichotomous noise appears in a wide variety of physical and mathematical models. It has escaped attention that the standard results for the long time properties cannot be applied when unstable fixed points are crossed in the asymptotic regime. We show how calculations have to be modified to deal with these cases and present as a first application full analyt

Vadim I. Puller, Lev G. Mourokh, Norman J. M. Horing, Anatoly Yu. Smirnov

A fully microscopic theory of electron spin relaxation by the D&#39;yakonov-Perel&#39; type spin-orbit coupling is developed for a semiconductor quantum well with a magnetic field applied in the growth direction of the well. We derive the Bloch equations for an electron spin in the well and define microscopic expressions for the spin relaxation times. The de

H. Aratyn, J. F. Gomes, A. H. Zimerman

We present a class of three-dimensional integrable structures associated with the Darboux-Egoroff metric and classical Euler equations of free rotations of a rigid body. They are obtained as canonical structures of rational Landau-Ginzburg potentials and provide solutions to the Painleve VI equation.

Michael H. Freedman, Kevin Walker, Zhenghan Wang

The Jones-Witten theory gives rise to representations of the (extended) mapping class group of any closed surface Y indexed by a semi-simple Lie group G and a level k. In the case G=SU(2) these representations (denoted V_A(Y)) have a particularly simple description in terms of the Kauffman skein modules with parameter A a primitive 4r-th root of unity (r=k+2

Peter Ozsvath, Zoltan Szabo

In an earlier paper, we introduced a knot invariant for a null-homologous knot K in an oriented three-manifold Y, which is closely related to the Heegaard Floer homology of Y. In this paper we investigate some properties of these knot homology groups for knots in the three-sphere. We give a combinatorial description for the generators of the chain complex an

I. B. Rutel, S. A. Zvyagin, J. S. Brooks, J. Krzystek

A systematic electron spin resonance (ESR) investigation of the low temperature regime for the (ET)2SF5CF2SO3 system was performed in the frequency range of ~200-700 GHz, using backward wave oscillator sources, and at fields up to 25 T. Newly acquired access to the high frequency and fields shows experimental ESR results in agreement with the nuclear magneti

Gary Steigman

The first observations of deuterium and oxygen in the Local Interstellar Medium (LISM) obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) can be used to search for local abundance variations. While the very limited sample of these first data may be consistent with no variations, they do offer a hint of anti-correlated variations between D/H and

Elcio Abdalla, Bertha Cuadros-Melgar

We consider a dynamical membrane world in a space-time with scalar bulk matter described by domain walls. Using the solutions to Einstein field equations and Israel conditions we investigate the possibility of having shortcuts for gravitons leaving the wall and returning subsequently. As it turns out, they usually appear under mild conditions. In the compari

Xiulian Wang, Bo Feng, Mingzhe Li, Xue-Lei Chen

In the ``natural inflation&#39;&#39; model, the inflaton potential is periodic. We show that Planck scale physics may induce corrections to the inflaton potential, which is also periodic with a greater frequency. Such high frequency corrections produce oscillating features in the primordial fluctuation power spectrum, which are not entirely excluded by the c

Zohar Nussinov

We demonstrate that the application of any external uniform non-abelian gauge background, no matter how small, leads to a greatly enhanced degeneracy. This degeneracy is so large that even a non-abelian background field of infinitesimal strength leads to a shocking change in the thermodynamics. The critical temperature might be discontinuously depressed and

D. I. Kazakov

We consider gauge field theories in $D>4$ following the Wilson RG approach and show that they possess the ultraviolet fixed points where the gauge coupling is dimensionless in any space-time dimension. At the fixed point the anomalous dimensions of the field and vertex operators are known exactly. These fixed points are nonperturbative and correspond to conf

V. Krey, K. R. S. Balaji

In the framework of NRQCD and parton model, we estimate in detail,the production cross section for polarized J/psi from B meson decays. In order to contrast with data, we also take into account additional J/psi production due to decay of excited charmonium states. We calculate the helicity parameter, alpha, and as an application, we study our results for the

Geza Odor

The phase transition of the one-dimensional, diffusive pair contact process (PCPD) is investigated by N cluster mean-field approximations and high precision simulations. The N=3,4 cluster approximations exhibit smooth transition line to absorbing state by varying the diffusion rate D with beta_2=2 mean-field order parameter exponent of the pair density. This

Michael Dine, Yosef Nir, Guy Raz, Tomer Volansky

We study the consequences of time variations in the scale of grand unification, $M_U$, when the Planck scale and the value of the unified coupling at the Planck scale are held fixed. We show that the relation between the variations of the low energy gauge couplings is highly model dependent. It is even possible, in principle, that the electromagnetic couplin

V. A. Dolgushev

We present a classical $r$-matrix for the Hitchin system without marked points on an arbitrary non-degenerate algebraic curve of genus $g\ge 2$ using Tyurin parameterization of holomorphic vector bundles.

A. Crepieux, R. Guyon, P. Devillard, T. Martin

Transport through a metallic carbon nanotube is considered, where electrons are injected in the bulk by a scanning tunneling microscope tip. The charge current and noise are computed both in the absence and in the presence of one dimensional Fermi liquid leads. For an infinite homogeneous nanotube, the shot noise exhibits effective charges different from the

T. Aspelmeier, M. A. Moore, A. P. Young

The replica method has been used to calculate the interface free energy associated with the change from periodic to anti-periodic boundary conditions in finite-dimensional spin glasses. At mean-field level the interface free energy vanishes but after allowing for fluctuation effects, a non-zero interface free energy is obtained which is significantly differe

M. Guagnelli, F. Palombi, R. Petronzio, N. Tantalo

We discuss a novel method to calculate fB on the lattice based on the study of the dependence of finite size effects upon the heavy quark mass of flavoured mesons and on a non--perturbative recursive finite size technique. This method avoids the systematic errors related to extrapolations from the static limit or to the tuning of the coefficients of effectiv

Ulf Lindstrom, Maxim Zabzine

We study N=2 nonlinear two dimensional sigma models with boundaries and their massive generalizations (the Landau-Ginzburg models). These models are defined over either Kahler or bihermitian target space manifolds. We determine the most general local N=2 superconformal boundary conditions (D-branes) for these sigma models. In the Kahler case we reproduce the

T. Christodoulakis, G. O. Papadopoulos, A. Dimakis

The automorphisms of all 4-dimensional, real Lie Algebras are presented in a comprehensive way. Their action on the space of $4\times 4$, real, symmetric and positive definite, matrices, defines equivalence classes which are used for the invariant characterization of the 4-dimensional homogeneous spaces which possess an invariant basis.

Noam Soker, Joel H. Kastner

We investigate the consequences of magnetic flares on the surface of asymptotic giant branch (AGB) and similar stars. In contrast to the solar wind, in the winds of AGB stars the gas cooling time is much shorter than the outflow time. As a result, we predict that energetic flaring will not inhibit, and may even enhance, dust formation around AGB stars. If ma

B. V. Ivanov

The stationary gravitational field of two identical counter-moving beams of pure radiation is found in full generality. The solution depends on an arbitrary function and a parameter which sets the scale of the energy density. Some of its properties are studied. Previous particular solutions are derived as subcases.

Alexey V. Shchepetilov

Let $G$ be the identity component of the isometry group for an arbitrary curved two-point homogeneous space $M$. We consider algebras of $G$-invariant differential operators on bundles of unit spheres over $M$. The generators of this algebra and the corresponding relations for them are found. The connection of these generators with two-body problem on two-po

Thomas A. Prince, Massimo Tinto, Shane L. Larson, J. W. Armstrong

The multiple Doppler readouts available on the Laser Interferometer Space Antenna (LISA) permit simultaneous formation of several interferometric observables. All these observables are independent of laser frequency fluctuations and have different couplings to gravitational waves and to the various LISA instrumental noises. Within the functional space of int

Kiyoshi Shiraishi, Kenji Sakamoto, Nahomi Kan

We construct a six-dimensional Maxwell theory using a latticized extra space, the continuum limit of which is a shifted torus recently discussed by Dienes. This toy model exhibits the correspondence between continuum theory and discrete theory, and give a geometrical insight to theory-space model building.

Armen M. Atoyan, Charles D. Dermer

We treat the production of neutrons, photons, and neutrinos through photomeson interactions of relativistic protons with ambient photons in the compact inner jets of blazars. We show that the presence of the external UV radiation field makes possible strong energy losses already for protons with energies > 1 PeV, while without this component effective energy

F. Benatti, H. Narnhofer, A. Uhlmann

We compare some recent computations of the entanglement of formation in quantum information theory and of the entropy of a subalgebra in quantum ergodic theory. Both notions require optimization over decompositions of quantum states. We show that both functionals are strongly related for some highly symmetric density matrices. We discuss the presence of brok

N. Debergh, J. Ndimubandi, B. Van den Bossche

We propose a general method for constructing quasi-exactly solvable potentials with three analytic eigenstates. These potentials can be real or complex functions but the spectrum is real. A comparison with other methods is also performed.

Yu Shi

For a multipartite system, we sort out all possible entanglements, each of which is among a set of subsystems. Each entanglement can be measured by a generalized relative entropy of entanglement, which is conserved on average under reversible local operations and classical communication (LOCC) defined for all the parties. Then we derive a series of inequalit

J. F. Traub, H. Wozniakowski

We study path integration on a quantum computer that performs quantum summation. We assume that the measure of path integration is Gaussian, with the eigenvalues of its covariance operator of order j^{-k} with k>1. For the Wiener measure occurring in many applications we have k=2. We want to compute an $\e$-approximation to path integrals whose integrands ar

M. P. Lorikyan

The results of the study of the multiwire porous dielectric detector and microstrip porous dielectric detector filled with porous CsI are presented. Detectors were exposed to $α$-particles with energy of 5.46 MeV and X-rays with energy of 5.9 keV and operated with a constant applied voltage. It is found that right after thermal deposition of the porous CsI l

A. M. Ignatov

The effect of the conducting electrode on the interaction of dust grains in a an ion flow is discussed. It is shown that two grains levitating above the electrode at the same height may attract one another. This results in the instability of a dust layer in a plasma sheath.

Frank Froemel, Stefan Leupold, Ulrich Mosel

We present a simple albeit self-consistent approach to the spectral function of light quarks in infinite quark matter. Relations between correlation functions and collision rates are used to calculate the spectral function in an iterative procedure. The quark interactions are described by the SU(2) Nambu--Jona-Lasinio model. Calculations were performed in th

F. Gulminelli, PH. Chomaz

Using information theory we derive a thermodynamics for systems evolving under a collective motion, i.e. under a time-odd constraint. An illustration within the Lattice gas Model is given for two model cases: a collision between two complex particles leading to a incomplete relaxation of the incoming momentum, and a self-similar expansion. A semi-quantitativ

V. L. Korotkikh, K. A. Chikin

A new process of a nuclear excitation to discrete states in peripheral heavy ion collisions is studied. High energy photons are emitted by the exited nuclei with energies up to a few tens GeV at angles of a few hundred microradians with respect to the beam direction. We show that a two stage process where an electron - positron pair is produced by virtual ph

L. G. Moretto, J. B. Elliott, L. Phair, G. J. Wozniak

Recent analyses of multifragmentation in terms of Fisher&#39;s model and the related construction of a phase diagram brings forth the problem of the true existence of the vapor phase and the meaning of its associated pressure. Our analysis shows that a thermal emission picture is equivalent to a Fisher-like equilibrium description which avoids the problem of

Denis I. Borisov

We consider a singular perturbed eigenvalue problem for Laplace operator in a cylinder with frequent interchange of type of boundary condition on a lateral surface. These boundary conditions are prescribed by partition of lateral surface in a great number of narrow strips on those the Dirichlet and Neumann conditions are imposed by turns. We study the case o

Irena Swanson

This paper gives a complete primary decomposition of the first, that is, the smallest, Mayr-Meyer ideal, its radical, and the intersection of its minimal components. The particular membership problem which makes the Mayr-Meyer ideals&#39; complexity doubly exponential in the number of variables is here examined also for the radical and the intersection of th

Klaus Altmann, Bernd Sturmfels

There is a natural infinite graph whose vertices are the monomial ideals in a polynomial ring. The definition involves Gröbner bases or the action of an algebraic torus. We present algorithms for computing the (affine schemes representing) edges in this graph. We study the induced subgraphs on multigraded Hilbert schemes and on square-free monomial ideals. I

Martijn van Manen

Conflict sets are loci of intersecting wavefronts emanating from $l$ different surfaces. We show that generically conflict sets are Legendrian: locally they admit the structure of wavefronts. Simple stable singularities for this problem in $\R^n$ occur when $0 \leq n-l \leq 4$. Other related sets, such as kite curves and centre sets are also defined and disc

Johannes Sjoestrand

We consider resonances in the semi-classical limit, generated by a single closed hyperbolic orbit, for an operator on ${\bf R}^2$. We determine all such resonancess in a domain independent of the semi-classical parameter As an application we determine all resonances generated by a saddle point in a fixed disc around the critical energy.

Omer Angel, Itai Benjamini, Balint Virag

We introduce planar random walk conditioned to avoid its past convex hull, and we show that it escapes at a positive limsup speed. Experimental results show that fluctuations from a limiting direction are on the order of n^(3/4). This behavior is also observed for the extremal investor, a natural financial model related to the planar walk.

Bernhard Krön, Elmar Teufl

It is shown explicitly how self-similar graphs can be obtained as `blow-up&#39; constructions of finite cell graphs $\hat C$. This yields a larger family of graphs than the graphs obtained by discretising continuous self-similar fractals. For a class of symmetrically self-similar graphs we study the simple random walk on a cell graph $\hat C$, starting in a

Alain Connes

We analyse the noncommutative space underlying the quantum group SUq(2) from the spectral point of view which is the basis of noncommutative geometry, and show how the general theory developped in our joint work with H. Moscovici applies to the specific spectral triple defined by Chakraborty and Pal. This provides the pseudo-differential calculus, the Wodzci

A. Duff

In this paper we describe the derivations of orthosymplectic Lie superalgebras over a superring. In particular, we derive sufficient conditions under which the derivations can be expressed as a semidirect product of inner and outer derivations. We then present some examples for which these conditions hold.

Toshihiko Matsuki

It was proved by Huckleberry that the Akhiezer-Gindikin domain is included in the ``Iwasawa domain&#39;&#39; using complex analysis. But we can see that we need no complex analysis to prove it. In this paper, we generalize the notions of the Akhiezer-Gindikin domain and the Iwasawa domain for two associated symmetric subgroups in real Lie groups and prove th

Michael Entov, Leonid Polterovich

We prove that the group of area-preserving diffeomorphisms of the 2-sphere admits a non-trivial homogeneous quasimorphism to the real numbers with the following property. Its value on any diffeomorphism supported in a sufficiently small open subset of the sphere equals to the Calabi invariant of the diffeomorphism. This result extends to more general symplec