January 2006 arXiv papers — page 29

Peter M. Weilbacher, Pierre-Alain Duc

The galaxy pair AM 1353-272 nicknamed "The Dentist's Chair" shows two ~30 kpc long tidal tails. Previous observations using multi-slit masks showed that they host up to seven tidal dwarf galaxies. The kinematics of these tidal dwarfs appeared to be decoupled from the surrounding tidal material. New observations of the tip of the southern tidal ta

I. Georgantopoulos, K. Nandra, M. Brotherton, A. Georgakakis

We present Chandra and XMM observations of 12 bright (f(2-10 keV) > 10^-13 cgs) sources from the ASCA SHEEP (Search for the High Energy Extragalactic Population) survey. Most of these have been either not observed or not detected previously with the ROSAT mission and therefore they constitute a sample biased towards hard sources. The Chandra observations are

Rodrigo Fernández, Alexis Brandeker, Yanqin Wu

(Abridged) The main sequence star beta Pictoris hosts the best studied circumstellar disk to date. Nonetheless, a long-standing puzzle has been around since the detection of metallic gas in the disk: radiation pressure from the star should blow the gas away, yet the observed motion is consistent with Keplerian rotation. In this work we search for braking mec

R. Ramachandran, P. Demorest, D. C. Backer, I. Cognard

We report here on variable propagation effects in over twenty years of multi-frequency timing analysis of pulsar PSR B1937+21 that determine small-scale properties of the intervening plasma as it drifts through the sight line. The phase structure function derived from the dispersion measure variations is in remarkable agreement with that expected from the Ko

M. Chernyakova, A. Neronov, A. Lutovinov, J. Rodriguez

PSR B1259-63 is in a highly eccentric 3.4 year orbit with a Be star and crosses the Be star disc twice per orbit, just prior to and just after periastron. Unpulsed radio, X-ray and gamma-ray emission observed from the binary system is thought to be due to the collision of pulsar wind with the wind of Be star. We present here the results of new XMM-Newton obs

Christophe Martayan, Yves Fremat, Anne-Marie Hubert, Michele Floquet

Spectroscopic observations of hot stars belonging to the young cluster LMC-NGC 2004 and its surrounding region were carried out with the VLT-GIRAFFE facilities in MEDUSA mode. We determine fundamental parameters (Teff, logg, vsini, and radial velocity), for all B and Be stars in the sample thanks to a code developed in our group. The effect of fast rotation

S. Randich, P. Sestito, F. Primas, R. Pallavicini

We determined the metallicity ([Fe/H]), together with O, Na, Mg, Al, Si, Ca, Ti, Cr and Ni abundances for a sample of 10 unevolved or slightly evolved stars belonging to the open cluster M 67. We find an average metallicity [Fe/H]=0.03 +/- 0.01, in very good agreement with previous determinations. All the [X/Fe] abundance ratios are very close to solar. The

M. Dall'ora, G. Bono, J. Storm, F. Caputo

We present new observational results on the RR Lyrae K-band Period-Luminosity relation (PLK). Data on the Galactic globular clusters NGC 3201 and NGC 4590 (M68), and on the Large Magellanic Cloud cluster Reticulum are shown. We compare the observed slopes of the PLK relations for these three clusters with those predicted by pulsational and evolutionary model

J. Iglesias-Paramo, V. Buat, T. T. Takeuchi, K. Xu

This work presents the main ultraviolet (UV) and far-infrared (FIR) properties of two samples of nearby galaxies selected from the GALEX ($λ= 2315$Å, hereafter NUV) and IRAS ($λ= 60μ$m) surveys respectively. They are built in order to get detection at both wavelengths for most of the galaxies. Star formation rate (SFR) estimators based on the UV and FIR emis

J. Robrade, J. H. M. M. Schmitt

We present results from a comparative study of XMM-Newton observations of four classical T Tauri stars (CTTS), namely BP Tau, CR Cha, SU Aur and TW Hya. In these objects coronal, i.e. magnetic, activity and as recently shown, magnetically funneled accretion are the processes likely to be responsible for the generation of X-ray emission. Variable X-ray emissi

Katrin Heitmann, Zarija Lukic, Salman Habib, Paul M. Ricker

We study the evolution of the mass function of dark matter halos in the concordance LCDM model at high redshift. We employ overlapping (multiple-realization) numerical simulations to cover a wide range of halo masses, 10^7-10^{15}h^{-1}M_\odot, with redshift coverage beginning at z=20. The Press-Schechter mass function is significantly discrepant from the si

Piet Hut

Galactic nuclei and globular clusters act as laboratories in which nature experiments with normal stars, neutron stars and black holes, through collisions and through the formation of bound states, in the form of binaries. The main difference with the usual Earth-based laboratories is that we cannot control the experiments. Instead, we have no choice but to

Yuri Aikawa, Hideko Nomura

We calculate the physical structure of protoplanetary disks by evaluating the gas density and temperature self-consistently and solving separately for the dust temperature. The effect of grain growth is taken into account by assuming a power-law size distribution and varying the maximum radius of grains a_max. In our fiducial model with a_max=10um, the gas i

Miguel A. de Avillez, Dieter Breitschwerdt

The statistical properties of interstellar turbulence are studied by means of three-dimensional high-resolution HD and MHD simulations of a SN-driven ISM. It is found that the longitudinal and transverse turbulent length scales have time averaged (over a period of 50 Myr) ratios of 0.5-0.6, almost similar to the one expected for isotropic homogeneous turbule

Daniel B. Nestor, David A. Turnshek, Sandhya M. Rao

We present the results from a spectroscopic survey for intervening MgII absorption in the spectra of 381 background QSOs conducted at the Multiple Mirror Telescope. This survey complements our earlier SDSS EDR MgII survey, extending our results to lower redshift ($z \simeq 0.15$) and weaker MgII $\lambda2796$ rest equivalent width ($W_0^{\lambda2796} \simeq

Charles Shapiro, Asantha Cooray

We revisit the estimation of higher order corrections to the angular power spectra of weak gravitational lensing. Extending a previous calculation of Cooray and Hu, we find two additional terms to the fourth order in potential perturbations of large-scale structure corresponding to corrections associated with the Born approximation and the neglect of line-of

Ping He, Jiren Liu, Long-Long Feng, Chi-Wang Shu

We investigate the statistical properties of cosmic baryon fluid in the nonlinear regime, which is crucial for understanding the large-scale structure formation of the universe. With the hydrodynamic simulation sample of the Universe in the cold dark matter model with a cosmological constant, we show that the intermittency of the velocity field of cosmic bar

Ching-Ming Chen, Tianjun Li, Dimitri V. Nanopoulos

We show that for supersymmetric AdS vacua on Type IIA orientifolds with flux compactifications, the RR tadpole cancellation conditions can be completely relaxed, and then the four-dimensional N=1 supersymmetry conditions are the main constraints on consistent intersecting D6-brane model building. We construct two kinds of three-family Pati-Salam models. In t

Roderik A. Overzier, R. J. Bouwens, N. J. G. Cross, B. Venemans

We present deep HST/ACS observations in g,r,i,z towards the z=4.1 radio galaxy TN J1338-1942 and its overdensity of >30 spectroscopically confirmed Lya emitters (LAEs). We select 66 g-band dropouts to z=27, 6 of which are also a LAE. Although our color-color selection results in a relatively broad redshift range centered on z=4.1, the field of TN J1338-1942

Bjorn Garbrecht, Apostolos Pilaftsis

We study F-term hybrid inflation in a novel supersymmetric extension of the SM with a subdominant Fayet-Iliopoulos D-term. We call this particular form of inflation, in short, F_D-term hybrid inflation. The proposed model ties the mu-parameter of the MSSM to an SO(3)-symmetric Majorana mass m_N, through the vacuum expectation value of the inflaton field. The

Sebastian Franco, David Vegh

Recently, a new way of deriving the moduli space of quiver gauge theories that arise on the world-volume of D3-branes probing singular toric Calabi-Yau cones was conjectured. According to the proposal, the gauge group, matter content and tree-level superpotential of the gauge theory is encoded in a periodic tiling, the dimer graph. The conjecture provides a

Maria Rodriguez Martinez, Tsvi Piran

Gamma ray bursts are excellent candidates to constrain physical models which break Lorentz symmetry. We consider deformed dispersion relations which break the boost invariance and lead to an energy-dependent speed of light. In these models, simultaneously emitted photons from cosmological sources reach Earth with a spectral time delay that depends on the sym

Sebastien Viscardy

In the second half of the 19th century, the kinetic theory of gases has probably raised one of the most impassioned debates in the history of science. The so-called reversibility paradox around which intense polemics occurred reveals the apparent incompatibility between the microscopic and macroscopic levels. While classical mechanics describes the motion of

L. S. Schulman, D. Tolkunov, E. Mihokova

Using two methods we show that a quantized discrete breather in a 1-D lattice is stable. One method uses path integrals and compares correlations for a (linear) local mode with those of the quantum breather. The other takes a local mode as the zeroth order system relative to which numerical, cutoff-insensitive diagonalization of the Hamiltonian is performed.

Ben Craps, Arvind Rajaraman, Savdeep Sethi

We study the leading quantum effects in the recently introduced Matrix Big Bang model. This amounts to a study of supersymmetric Yang-Mills theory compactified on the Milne orbifold. We find a one-loop potential that is attractive near the Big Bang. Surprisingly, the potential decays very rapidly at late times, where it appears to be generated by D-brane eff

P. M. Ferreira, R. Santos

We study the effects of dimension six effective operators on the production of single top quarks at the LHC. The operator set considered includes terms with effective gluon interactions and four-fermion terms. Analytic expressions for the several partonic cross sections of single top production will be presented, as well as the results of their integration o

Jeff Crowder, Neil J. Cornish, Lucas Reddinger

This work presents the first application of the method of Genetic Algorithms (GAs) to data analysis for the Laser Interferometer Space Antenna (LISA). In the low frequency regime of the LISA band there are expected to be tens of thousands galactic binary systems that will be emitting gravitational waves detectable by LISA. The challenge of parameter extracti

Richard J. Cool, Daniel J. Eisenstein, David W. Hogg, Michael R. Blanton

In this paper, we present Sloan Digital Sky Survey (SDSS) photometry and spectroscopy in the fields of 24 gamma-ray bursts (GRBs) observed by Swift, including bursts localized by Swift, HETE-2, and INTEGRAL, after December 2004. After this bulk release, we plan to provide individual releases of similar data shortly after the localization of future bursts fal

Sergio Benvenuti, Leopoldo A. Pando Zayas, Yuji Tachikawa

The triangle anomalies in conformal field theory, which can be used to determine the central charge a, correspond to the Chern-Simons couplings of gauge fields in AdS under the gauge/gravity correspondence. We present a simple geometrical formula for the Chern-Simons couplings in the case of type IIB supergravity compactified on a five-dimensional Einstein m

G. Kaniadakis

In special relativity the mathematical expressions, defining physical observables as the momentum, the energy etc, emerge as one parameter (light speed) continuous deformations of the corresponding ones of the classical physics. Here, we show that the special relativity imposes a proper one parameter continuous deformation also to the expression of the class

Krzysztof M. Graczyk, Cezary Juszczak, Jan T. Sobczyk

Quark-hadron duality in neutrino-nucleon reactions is investigated under the assumption that cross sections in the resonance region are given by the Rein-Sehgal model. The quantitative analysis of the duality is done by means of appropriate integrals of the structure functions in the Nachtmann variable. We conclude that with the definition of the resonance r

Jing-Jing Li, Jie Ren, Zhi Liang, Meng Xu

This paper contains some immature results. It have been withdrawn.

Georg Biedermann, Boris Chorny, Oliver Röndigs

The category of small covariant functors from simplicial sets to simplicial sets supports the projective model structure. In this paper we construct various localizations of the projective model structure and also give a variant for functors from simplicial sets to spectra. We apply these model categories in the study of calculus of functors, namely for a cl

Mordehai Milgrom

I show that massive-particle dynamics can be simulated by a weak, spherical, external perturbation on a potential flow in an ideal fluid. The effective Lagrangian is of the form mc^2L(U^2/c^2), where U is the velocity of the particle relative to the fluid and c the speed of sound. This can serve as a model for emergent relativistic inertia a la Mach's pr

A. S. Alexandrov

Significantly different normal state Lorenz numbers have been found in two independent direct measurements based on the Righi-Leduc effect, one about 6 times smaller and the other one about 2 times larger than the Sommerfeld value in single cuprate crystals of the same chemical composition. The controversy is resolved in the model where charge carriers are m

David A. Lowe, Larus Thorlacius

String theory provides numerous examples of duality between gravitational theories and unitary gauge theories. To resolve the black hole information paradox in this setting, it is necessary to better understand how unitarity is implemented on the gravity side. We argue that unitarity is restored by nonlocal effects whose initial magnitude is suppressed by th

Maria C. Babiuc, Bela Szilagyi, Jeffrey Winicour

Computational techniques which establish the stability of an evolution-boundary algorithm for a model wave equation with shift are incorporated into a well-posed version of the initial-boundary value problem for gravitational theory in harmonic coordinates. The resulting algorithm is implemented as a 3-dimensional numerical code which we demonstrate to provi

Luc Molinet

We prove that the Benjamin-Ono equation is globally well-posed in $ H^s(\T) $ for $ s\ge 0 $. Moreover we show that the associated flow-map is Lipschitz on every bounded set of $ {\dot H}^s(\T) $, $s\ge 0$, and even real-analytic in this space for small times. This result is sharp in the sense that the flow-map (if it can be defined and coincides with the st

Indrajit Mitra, Raghunath Ratabole, H. S. Sharatchandra

Instability in the scalar channel of the fermion-antifermion scattering amplitude in massless QED_3 for number of flavours less than the critical value 128/3π^2 is demonstrated. The anomalous dimensions of gauge-invariant composite operators are determined to O(1/N). Exponentiation of the O(1/N) infrared logarithm is explicitly demonstrated by evaluating the

Hermann Zangerle, Jens Könemann, Brigitte Mackrodt, Ralf Dolata

We present investigations of Josephson charge-phase qubits inductively coupled to a radio-frequency driven tank-circuit enabling the readout of the states by measuring the Josephson inductance of the qubit. The circuits including junctions with linear dimensions of 60 nm and 80 nm are fabricated from Nb trilayer and allowing the determination of relevant sam

Kacper Kornet, Sebastian Wolf

We have investigated the problem of the distribution of both masses and orbital radii of planets resulting from the gas-accretion, gas-capture model. First we followed the evolution of gas and solids from the moment where all solids are in the form of small grains to the stage when most of them are in the form of planetesimals for a set of different initial

Matias Aiello, Gabriel Bengochea, Rafael Ferraro

Born-Infeld electromagnetic waves interacting with a static magnetic background are studied in an expanding universe. The non-linear character of Born-Infeld electrodynamics modifies the relation between the energy flux and the distance to the source, which gains a new dependence on the redshift that is governed by the background field. We compute the lumino

Jeffrey Diller, Vincent Guedj

For meromorphic maps of complex manifolds, ergodic theory and pluripotential theory are closely related. In nice enough situations, dynamically defined Green's functions give rise to invariant currents which intersect to yield measures of maximal entropy. `Nice enough' is often a condition on the regularity of the Green's function. In this paper

Dalia Chakrabarty

The observed radial and transverse velocities of individual stars in M15 are implemented as inputs to a fully non-parametric code (CHASSIS) in order to estimate the equilibrium stellar distribution function and the three-dimensional mass density profile. In particular, the paper explores the possibility of the existence of a central black hole in M15 via sev

Bo Hu, Yi Ling, Hongbao Zhang

Quantum inequalities have been established for various quantum fields in both flat and curved spacetimes. In particular, for spin-3/2 fields, Yu and Wu have explicitly derived quantum inequalities for massive case. Employing the similar method developed by Fewster and colleagues, this paper provides an explicit formula of quantum inequalities for massless sp

Hermann Freire, Eberth Correa, Alvaro Ferraz

We analyze the one-dimensional (1D) and the two-dimensional (2D) repulsive Hubbard models (HM) for densities slightly away from half-filling through the behavior of two central quantities of a system: the uniform charge and spin susceptibilities. We point out that a consistent renormalization group treatment of them can only be achieved within a two-loop app

Alberto Della Vedova, Roberto Paoletti

The study of the volume of big line bundles on a complex projective manifold M has been one of the main veins in the recent interest in the asymptotic properties of linear series. In this article, we consider an equivariant version of this problem, in the presence of a linear action of a reductive group on M. The results in this paper extend and improve thos

F. A. Majeed, A. A. Auda

The level schemes and transition rates {\em B}({\em E}2;$\uparrow$) of eve-even $^{48-56}$Ti isotopes were studied by performing large-scale shell model calculations with FPD6 and GXPF1 effective interactions. Excellent agreement were obtained by comparing the first 2$^{+}$ level for all isotopes with the recently available experimental data, but studying th

Jun Ohkubo, Muneki Yasuda, Kazuyuki Tanaka

We analyse a preferential urn model with randomness using the replica method. The preferential urn model is a stochastic model based on the concept "the rich get richer." The replica analysis clarifies that the preferential urn model with randomness shows a fat-tailed occupation distribution. The analytical treatments and results would be useful for

V. P. Goncalves, W. K. Sauter

In this Letter we study the double diffractive vector meson production in $e^+e^-$ collisions assuming the dominance of the BFKL pomeron exchange. We consider the non-forward solution of the BFKL equation at high energy and large momentum transfer and estimate the total cross section for the process $e^+e^- \to e^+e^- V_1 V_2$ with antitagged $e^+$ and $e^-$

Adrian Palcu

The unjustly neglected method of exactly solving generalized electro-weak models - with an original spontaneous symmetry breaking mechanism based on the gauge group $SU(n)_{L}\otimes U(1)_{Y}$ - is applied here to a particular class of chiral 3-3-1 models. This procedure enables us - without resorting to any approximation - to express the boson mass spectrum

Jih-Hsin Cheng, Jenn-Fang Hwang, Paul Yang

In \cite{CHMY04}, we studied $p$-mean curvature and the associated $p$-minimal surfaces in the Heisenberg group from the viewpoint of PDE and differential geometry. In this paper, we look into the problem through the variational formulation. We study a generalized $p$-area and associated ($p$-) minimizers in general dimensions. We prove the existence and inv

Eric Bertin, Maxime Clusel

We show that generalised extreme value statistics -the statistics of the k-th largest value among a large set of random variables- can be mapped onto a problem of random sums. This allows us to identify classes of non-identical and (generally) correlated random variables with a sum distributed according to one of the three (k-dependent) asymptotic distributi

Jun'ichi Yokoyama

It is shown that the coherent field oscillation of moduli fields with weak or TeV scale masses can dissipate its energy efficiently if they have a derivative coupling to standard bosonic fields in a thermal state. This mechanism may provide a new solution to the cosmological moduli problem in some special situations.

Fedele Lizzi, Sachindeo Vaidya, Patrizia Vitale

By twisting the commutation relations between creation and annihilation operators, we show that quantum conformal invariance can be implemented in the 2-d Moyal plane. This is an explicit realization of an infinite dimensional symmetry as a quantum algebra.

Slava G. Turyshev, Michael Shao, Kenneth L. Nordtvedt

The Laser Astrometric Test Of Relativity (LATOR) is a Michelson-Morley-type experiment designed to achieve a major improvement in the accuracy of the tests of relativistic gravity in the solar system. By using a combination of independent time-series of gravitational deflection of light in the immediate proximity to the Sun, along with measurements of the re

C. Y. Ryu, C. H. Hyun, S. W. Hong, B. T. Kim

We use the modified quark-meson coupling (MQMC) model to study the composition profile of neutron star matter and compare the results with those calculated by quantum hadrodynamics (QHD). Both MQMC and QHD model parameters are adjusted to produce exactly the same saturation properties so that we can investigate the model dependences of the matter composition

Ezra Miller, David E Speyer

Fix a variety X with a transitive (left) action by an algebraic group G. Let E and F be coherent sheaves on X. We prove that, for elements g in a dense open subset of G, the sheaf Tor_i^X(E, g F) vanishes for all i > 0. When E and F are structure sheaves of smooth subschemes of X in characteristic zero, this follows from the Kleiman-Bertini theorem; our resu

M. Schröter, S. Ulrich, J. Kreft, J. B. Swift

A granular mixture of particles of two sizes that is shaken vertically will in most cases segregate. If the larger particles accumulate at the top of the sample, this is called the Brazil-nut effect (BNE); if they accumulate at the bottom, the reverse Brazil-nut effect (RBNE). While this process is of great industrial importance in the handling of bulk solid

Yong-Geun OH

In this paper, we study the dynamical aspects of the \emph{Hamiltonian homeomorphism group} $Hameo(M,\omega)$ which was introduced by M\"uller and the author. We introduce the notion of autonomous continuous Hamiltonian flows and extend the well-known conservation of energy to such flows. The definitions of the Hofer length and of the spectral invariants $\r

M. L. Terraciano, R. Olson, D. L. Freimund, L. A. Orozco

We study the probe spectrum of light generated by spontaneous emission into the mode of a cavity QED system. The probe spectrum has a maximum on-resonance when the number of inverted atoms for an input drive is maximal. For a larger number of atoms N, the maximum splits and develops into a doublet, but its frequencies are different from those of the so-calle

D. A. R. Dalvit, G. P. Berman, M. Vishik

We consider the problem of decoherence and relaxation of open bosonic quantum systems from a perspective alternative to the standard master equation or quantum trajectories approaches. Our method is based on the dynamics of expectation values of observables evaluated in a coherent state representation. We examine a model of a quantum nonlinear oscillator wit

R. Srikanth

A conceptual difficulty in the foundations of quantum mechanics is the quantum measurement problem (QMP), essentially concerned with the apparent non-unitarity of the measurement process and the classicality of macroscopic systems. In an information theoretic approach proposed by us earlier (Quantum Information Processing 2, 153, 2003), which we clarify and

Filippo Neri

This note is a comment on the "quantum interferometry" section of Reference [1]. It points out that the methods of that section can be applied to more general states than the ones that are discussed in Ref. [1].

R. Simon, S. Chaturvedi, V. Srinivasan, N. Mukunda

Hamilton in the course of his studies on quaternions came up with an elegant geometric picture for the group SU(2). In this picture the group elements are represented by ``turns'', which are equivalence classes of directed great circle arcs on the unit sphere $S^2$, in such a manner that the rule for composition of group elements takes the form of th

Arvind, S. Chaturvedi, N. Mukunda, R. Simon

The well known Poisson Summation Formula is analysed from the perspective of the coherent state systems associated with the Heisenberg--Weyl group. In particular, it is shown that the Poisson summation formula may be viewed abstractly as a relation between two sets of bases (Zak bases) arising as simultaneous eigenvectors of two commuting unitary operators i

M. Sasaki, K. Wakui, J. Mizuno, M. Fujiwara

We present the two kinds of experimental results. One is a continuous variable dense coding experiment, and the other is a photon number detector with high linearity response, the so called charge integration photon detector (CIPD). They can be combined together to be a potential tool for implementing the cubic phase gate which is an important gate element t

Peter Hänggi, Gert-Ludwig Ingold

The quantum thermodynamic behavior of small systems is investigated in presence of finite quantum dissipation. We consider the archetype cases of a damped harmonic oscillator and a free quantum Brownian particle. A main finding is that quantum dissipation helps to ensure the validity of the Third Law. For the quantum oscillator, finite damping replaces the z

T. Chaneliere, D. N. Matsukevich, S. D. Jenkins, T. A. B. Kennedy

A quantum repeater at telecommunications wavelengths with long-lived atomic memory is proposed, and its critical elements are experimentally demonstrated using a cold atomic ensemble. Via atomic cascade emission, an entangled pair of 1530 nm and 780 nm photons is generated. The former is ideal for long-distance quantum communication, and the latter is natura

David O. Kashinski, Paul V. Quinn

In the past, the gravitational acceleration on the surface of the Earth, $g$, has been measured in many ways. Various methods include the use of a pendulum as well as models involving the use of a mass on a spring. We have designed a new method incorporating the mass-spring model with a capacitor, and a capacitance meter. This capacitor model still uses a ha

M. Marklund, P. K. Shukla

The properties of amplitude modulated broadband Alfven waves is investigated. In particular, the dynamics of circularly polarized dispersive Alfven waves, governed by a derivative nonlinear Schroedinger equation, is analyzed using the Wigner formalism. The modulational instability of random phase dispersive pump Alfven waves is investigated, and it is shown

Miroslaw Kozlowski, Janina Marciak-Kozlowska

In this paper the existence of the thermal tachyons i.e. quanta of temperature field, with is described in the theoretical frame of hyperbolic thermal equation. The modified Lorentz transformation are developed. It is argued that thermal tachyons can exist in accordance with modified Lorentz transformation after change . The thermal tachyons fulfill the hype

Gerhard Schmid, Igor Goychuk, Peter Hanggi

Using a stochastic generalization of the Hodgkin–Huxley model, we consider the influence of intrinsic channel noise on the synchronization between the spiking activity of the excitable membrane and an externally applied periodic signal. For small patches, i.e., when the channel noise dominates the excitable dynamics, we find the phenomenon of intrinsic

Jean-Philippe Laval, Pierre Blaineau, Nicolas Leprovost, Bérengère Dubrulle

We use direct and stochastic numerical simulations of the magnetohydrodynamic equations to explore the influence of turbulence on the dynamo threshold. In the spirit of the Kraichnan-Kazantsev model, we model the turbulence by a noise, with given amplitude, injection scale and correlation time. The addition of a stochastic noise to the mean velocity signific

Ruggero Maria Santilli

It was generally believed throughout the 20-th century that irreversibility is a purely classical event without operator counterpart. However, a classical irreversible system cannot be consistently decomposed into a finite number of reversible quantum particles (and, vice versa), thus establishing that the origin of irreversibility is basically unknown at th

Fred H. Thaheld

Recent experiments appear to have revealed the possibility of quantum entanglement between spatially separated human subjects. In addition, a similar condition might exist between basins containing human neurons adhering to printed circuit boards. In both instances, preliminary data indicates what appear to be non-local correlations between brain electrical

P. Castorina, P. P. Delsanto, C. Guiot

A classification in universality classes of broad categories of phenomenologies, belonging to different disciplines, may be very useful for a crossfertilization among them and for the purpose of pattern recognition. We present here a simple scheme for the classification of nonlinear growth problems. The success of the scheme in predicting and characterizing

Peter Wagner

The data presented here show that human drivers apply a discrete noisy control mechanism to drive their vehicle. A car-following model built on these observations, together with some physical limitations (crash-freeness, acceleration), led to non-Gaussian probability distributions in the speed difference and distance which are in good agreement with empirica

Mika Gustafsson, Anna Lombardi, Michael Hornquist

The issue of partitioning a network into communities has attracted a great deal of attention recently. Most authors seem to equate this issue with the one of finding the maximum value of the modularity, as defined by Newman. Since the problem formulated this way is NP-hard, most effort has gone into the construction of search algorithms, and less to the ques

Pekka Alitalo, Stanislav Maslovski, Sergei Tretyakov

Design and experimental realization of a three-dimensional superlens based on LC-loaded transmission lines are presented. Commercially available components and materials are used in the design. Transmission properties of the designed structure are studied experimentally and the observed lens properties are compared with analytical predictions. Backward-wave

A. K. Popov, Vladimir M. Shalaev

Second harmonic generation and optical parametric amplification in negative-index metamaterials (NIMs) are studied. The opposite directions of the wave vector and the Poynting vector in NIMs results in a "backward" phase-matching condition, causing significant changes in the Manley-Rowe relations and spatial distributions of the coupled field intensi

R. L. Collins

Hubble plots of the distance of stellar objects vs. recession velocity normally assume the red shift is wholly Doppler and ignore any gravitational contribution. This is unwarranted: gravity and Doppler velocity red shifts are found to be separable and contribute about equally. A recent data set, to Z=1.2, by Riess (1), was analyzed. Upon plotting distance v

Rudolph C. Hwa, C. B. Yang

We relate the fragmentation functions of partons into mesons and baryons in the framework of recombination of shower partons. The results are in reasonable agreement with the data. The implication is that the meson and baryon fragmentation functions are not independent when hadronization of the shower partons are taken into account. The conclusion therefore

Reinhard Alkofer, Pedro Bicudo, Stephen R. Cotanch, Christian S. Fischer

We study dynamical mass generation in pure Yang-Mills theory and report on a recently developed ansatz that exactly solves the tower of Dyson-Schwinger equations in Landau gauge at low Euclidean momentum, featuring enhanced gluon-gluon vertices, a finite ghost-gluon vertex in agreement with an old argument of Taylor, and an IR suppressed gluon propagator. Th

A. Schiller, A. Voinov, E. Algin, L. A. Bernstein

The two published literature values [Greenwood et al., Nucl. Phys. A252, 260 (1975) and Gelletly et al., J. Phys. G 11, 1055 (1985)] for absolute primary gamma intensities following thermal neutron capture of 171Yb differ in average by a factor of three. We have resolved this conflict in favor of Greenwood et al. by a measurement of primary versus secondary

Helen Caines

Preliminary results on strange particle production versus collision centrality are presented. STAR measurements from \sqrts = 200 GeV heavy-ion and \pp collisions are compared to SPS measurements. A systematic study of strange particle production is presented with the aim of establishing how the correlation volume of the produced source affects the scale of

W. T. Lu, Weiqiao Zeng, S. Sridhar

We establish a duality between the quantum wave vector spectrum and the eigenmodes of the classical Liouvillian dynamics for integrable billiards. Signatures of the classical eigenmodes appear as peaks in the correlation function of the quantum wave vector spectrum. A semiclassical derivation and numerical calculations are presented in support of the results

Michel Destrade, Giuseppe Saccomandi

We show that a model proposed by Rubin, Rosenau, and Gottlieb [J. Appl. Phys. 77 (1995) 4054], for dispersion caused by an inherent material characteristic length, belongs to the class of simple materials. Therefore, it is possible to generalize the idea of Rubin, Rosenau, and Gottlieb to include a wide range of material models, from nonlinear elasticity to

T. Gorin, H. Kohler, T. Prosen, T. H. Seligman

Symmetries as well as other special conditions can cause anomalous slowing down of fidelity decay. These situations will be characterized, and a family of random matrix models to emulate them generically presented. An analytic solution based on exponentiated linear response will be given. For one representative case the exact solution is obtained from a supe

M. Adler, P. van Moerbeke, P. Vanhaecke

In a recent publication, it was shown that a large class of integrals over the unitary group U(n) satisfy difference equations over $n$, involving a finite number of steps; special cases are generating functions appearing in questions of longest increasing subsequences in random permutations and words. The main result of the paper states that these differenc

Andrei Caldararu

We show that fiberwise stable vector bundles are preserved by relative Fourier-Mukai transforms between elliptic threefolds with relative Picard number one. Using these bundles we define new invariants of elliptic fibrations, and we relate the invariants of a space with those of a relative moduli space of stable sheaves on it. As a byproduct, we calculate th

Martin P. W. Zerner

We investigate excited random walks on $\Z^d, d\ge 1,$ and on planar strips $\Z\times\{0,1,...,L-1\}$ which have a drift in a given direction. The strength of the drift may depend on a random i.i.d. environment and on the local time of the walk. We give exact criteria for recurrence and transience, thus generalizing results by Benjamini and Wilson for once-e

Marina Nechayeva, Burton Randol

We study the asymptotic behavior of discrete measures on S^{n-1} that are induced by radially projecting point masses concentrated on the integral lattice-points within dilates of a compact body D, for various classes of D. The results depend sensitively on the differential geometric properties of the boundary of D.

Craig R. Guilbault

In this note we present a characterization of those open n-manifolds (n>4), whose products with the real line are homeomorphic to interiors of compact (n+1)-manifolds with boundary.

M. Skeide

(See detailed abstract in the article.) We single out the correct class of spatial product systems (and the spatial endomorphism semigroups with which the product systems are associated) that allows the most far reaching analogy in their classifiaction when compared with Arveson systems. The main differences are that mere existence of a unit is not it suffic

Jozef H. Przytycki

In this chapter (Chapter V) we present several results which demonstrate a close connection and useful exchange of ideas between graph theory and knot theory. These disciplines were shown to be related from the time of Tait (if not Listing) but the great flow of ideas started only after Jones discoveries. The first deep relation in this new trend was demonst

N. Brodskiy, J. Dydak, J. Higes, A. Mitra

In the first part of the paper we show how to relate several dimension theories (asymptotic dimension with Higson property, asymptotic dimension of Gromov, and capacity dimension of Buyalo \cite{Buyalo1}) to Nagata-Assouad dimension. This is done by applying two functors on the Lipschitz category of metric spaces: microscopic and macroscopic. In the second p

Amaël Broustet

We compute in this note the Seshadri constants of the anticanonical bundle at every point of Del Pezzo surfaces. During the proof, we enlight the role of rational curves in our computations. We present then two exemples where the positivity of the anticanonical bundle cannot be detected using rational curves.

Amos Nevo

The survey presents the main developments obtained over the last decade regarding pointwise ergodic theorems for measure preserving actions of locally compact groups. The survey includes an exposition of the solutions to a number of long standing open problems in ergodic theory, some of which are very recent and have not yet appeared elsewhere.

S. Akesbi, B. Brighi, J. -D. Hoernel

In this paper we are interested with a strongly coupled system of partial differential equations that modelizes free convection in a two-dimensional bounded domain filled with a fluid saturated porous medium. This model is inspired by the one of free convection near a semi-infinite impermeable vertical flat plate embedded in a fluid saturated porous medium.