July 2002 arXiv papers — page 23

Pierluigi Novi Inverardi, Alberto Petri, Giorgio Pontuale, Aldo Tagliani

We outline an efficient method for the reconstruction of a probability density function from the knowledge of its infinite sequence of ordinary moments. The approximate density is obtained resorting to maximum entropy technique, under the constraint of some fractional moments. The latter ones are obtained explicitly in terms of the infinite sequence of given

H. Reinholz, G. Roepke, A. Wierling, V. Mintsev

Experimental results for the reflection coefficient of shock-compressed dense Xenon plasmas at pressures of 1.6 - 17 GPa and temperatures around 30 000 K using a laser beam with λ= 1.06 10^-6 m are compared with calculations based on different theoretical approaches to the dynamical collision frequency. It is found that a reasonable description can be given

P. Boutachkov, A. Aprahamian, Y. Sun, J. A. Sheikh

The Triaxial Projected Shell Model (TPSM) has been successful in providing a microscopic description of the energies of multi-phonon vibrational bands in deformed nuclei. We report here on an extension of the TPSM to allow, for the first time, calculations of B(E2) values connecting gamma- and gamma-gamma-vibrational bands and the ground state band. The meth

A. Capella, C. A. Salgado, D. Sousa

We compute the mid-rapidity densities of pions, kaons, baryons and antibaryons in $Au$--$Au$ collisions at $\sqrt{s}$ = 130 GeV in the Dual Parton Model supplemented with final state interactions, and we present a comparison with available data.

Yasuro Funaki, Hisashi Horiuchi, Akihiro Tohsaki, Peter Schuck

In order to study non-zero spin excitations of the recently proposed alpha-cluster condensation in the self-conjugate 4n nuclei, spatial deformation is introduced into the model wave function of the alpha-cluster condensate. The rotational band states of 8Be are investigated as a first step of a test case for the study of the deformation of the alpha-cluster

Zhong-yu Ma, Ling Liu

A new decomposition of the Dirac structure of nucleon self-energies in the Dirac Brueckner-Hartree-Fock (DBHF) approach is adopted to investigate the equation of state for asymmetric nuclear matter. The effective coupling constants of $σ$, $ω$, $δ$ and $ρ$ mesons with a density dependence in the relativistic mean field approach are deduced by reproducing the

R. E. Zimmermann, A. Schlemm, D. Zeilinger, V. G. Budanov

Following the results and the general methodological framework of a preceeding paper (Models and Metaphors, part I, henceforth: MM), we develop some results on the epistemological state of natural laws and ask for explicit possibilities of mediating the contexts of nature (in terms of the sciences) and aesthetics.

R. E. Zimmermann, S. Ley, V. G. Budanov, V. E. Voitsekhovitch

The explicit relationship among perception, communication, and design is being discussed in some detail, in order to relate it to characteristic details of the modeling of the world which defines the scientific and artistic activities of humans, in the first place, but also the philosophical grasping of the world and its foundations in order to position huma

C. I. Siettos, A. Armaou, A. G. Makeev, I. G. Kevrekidis

Coarse timesteppers provide a bridge between microscopic / stochastic system descriptions and macroscopic tasks such as coarse stability/bifurcation computations. Exploiting this computational enabling technology, we present a framework for designing observers and controllers based on microscopic simulations, that can be used for their coarse control. The pr

Aristophanes Dimakis, Folkert Muller-Hoissen

In a series of publications we developed "differential geometry" on discrete sets based on concepts of noncommutative geometry. In particular, it turned out that first order differential calculi (over the algebra of functions) on a discrete set are in bijective correspondence with digraph structures where the vertices are given by the elements of the

Marek Biskup, Lincoln Chayes, Roman Kotecky

We consider liquid-vapor systems in finite volume $V\subset\R^d$ at parameter values corresponding to phase coexistence and study droplet formation due to a fixed excess $δN$ of particles above the ambient gas density. We identify a dimensionless parameter $Δ\sim(δN)^{(d+1)/d}/V$ and a \textrm{universal} value $\Deltac=\Deltac(d)$, and show that a droplet of

Ali Tahzibi

In this paper we show the relation between robust transitivity and robust ergodicity for conservative diffeomorphisms. In dimension 2 robustly transitive systems are robustly ergodic. For the three dimensional case, we define it almost robust ergodicity and prove that generically robustly transitive systems are almost robustly ergodic, if the Lyapunov expone

David McKinnon

In this paper, we prove a general result computing the number of rational points of bounded height on a projective variety $V$ which is covered by lines. The main technical result used to achieve this is an upper bound on the number of rational points of bounded height on a line. This upper bound is such that it can be easily controlled as the line varies, a

Tahl Nowik

We classify all finite order invariants of immersions of a closed orientable surface into R^3, with values in any Abelian group. We show that they are all functions of order one invariants.

S. V. Aksenov, M. A. Savageau, U. D. Jentschura, J. Becher

We discuss several applications of the recently proposed combined nonlinear-condensation transformation (CNCT) for the evaluation of slowly convergent, nonalternating series. These include certain statistical distributions which are of importance in linguistics, statistical-mechanics theory, and biophysics (statistical analysis of DNA sequences). We also dis

David Blanc, Martin Markl

We provide a general definition of higher homotopy operations, encompassing most known cases, including higher Massey and Whitehead products, and long Toda brackets. These operations are defined in terms of the W-construction of Boardman and Vogt, applied to the appropriate diagram category; we also show how some classical families of polyhedra (including si

William Cherry

A non-Archimedean analog of the classical Big Picard Theorem, which says that a holomorphic map from the punctured disc to a Riemann surface of hyperbolic type extends accross the puncture, is proven using Berkovich's theory of non-Archimedean analytic spaces.

Hiroshige Kajiura

It is known that the physics of open strings on a D2-brane on a two-torus is realized from the viewpoint of deformation quantization in the Seiberg-Witten limit. We study its T-dual theory, i.e. D1-brane physics on two-tori. Such theory is described by Kronecker foliation. The algebra of open strings on the D1-brane is then identified with the crossed produc

Sylvain Ribault

I review some recent progress in understanding the properties of AdS2 branes in AdS3. Different methods - classical string motion, Born-Infeld dynamics, boundary states - are evocated and compared.

Kayoko Fujimura

We show that a partition function on the not-flat D1-brane can be written in the same form as that on the flat one in $α^\prime$-order. In this case the information of the curvature of the brane configuration is included in tachyon beta function.

Dmitri Antonov

String representation of the $[U(1)]^{N-1}$ gauge-invariant dual Abelian-Higgs-type theory, which is relevant to the SU(N)-QCD with the $Θ$-term and provides confinement of quarks, is derived. The N-dependence of the Higgs vacuum expectation value is found, at which the tension of the string joining quarks becomes N-independent, similarly to the real QCD. Co

Mark Srednicki

We propose a resolution to the black-hole information-loss paradox: in one formulation of physical theory, information is preserved and macroscopic causality is violated; in another, causality is preserved and pure states evolve to mixed states. However, no experiments can be performed that would distinguish these two descriptions. We explain how this could

A. Havare, K. Sogut

This article illustrates a completely algebraic method to obtain the energy levels of a massive spin-1 particle moving in a constant magnetic field. In the process to obtain the energy levels the wave function was written by harmonic oscillator solutions.

Ben Freivogel, Steven B. Giddings, Matthew Lippert

To better understand the possible breakdown of locality in quantum gravitational systems, we pursue the identity of precursors in the context of AdS/CFT. Holography implies a breakdown of standard bulk locality which we expect to occur only at extremely high energy. We consider precursors that encode bulk information causally disconnected from the boundary a

B. L. Cerchiai, A. F. Pasqua, B. Zumino

The Seiberg-Witten map for noncommutative Yang-Mills theories is studied and methods for its explicit construction are discussed which are valid for any gauge group. In particular the use of the evolution equation is described in some detail and its relation to the cohomological approach is elucidated. Cohomological methods which are applicable to gauge theo

Nikolaos Kidonakis

I discuss recent progress in the calculation of two-loop QCD corrections in the eikonal approximation. I present specific results for the UV structure of the corrections.

Stefan Kretzer

Including the effects of the ${\cal{O}}(\gtrsim 1 {\rm GeV})$ masses of the charm quark, $τ$ lepton and target nucleon in DIS phenomenology is discussed with applications to CC neutrino DIS: Neutrino data for $F_2$ are revisited within the global analysis framework. A fully differential calculation refines the CC charm production process as a gate to extract

Ruben Flores-Mendieta

We compute nonanalytical pion-loop corrections to baryon masses in a combined expansion in chiral symmetry breaking and 1/N_c, where N_c is the number of colors. Specifically, we compute flavor-27 baryon mass splittings at leading order in chiral perturbation theory. Our results, at the physical value N_c=3, are compared with the expressions obtained in heav

Hu Li, C. M. Shakin

Recent years have seen extensive applications of the Nambu--Jona-Lasinio (NJL) model in the study of matter at high density. There is a good deal of interest in the predictions of diquark condensation and color superconductivity, with suggested applications to the study the properties of neutron stars. As the researchers in this field note, the NJL model doe

Massimo Di Pierro, Adam K. Leibovich

In this paper we compute, within in the context of a relativistic quark model, the Isgur-Wise functions for exclusive semileptonic $\bar B \to X_c$ decays, where $X_c$ is any charmed mesons with total spin $J=0,1,2$ or one of their first excited states. The relevant matrix elements are computed by a direct numerical integration, in coordinate space, of the c

Andrzej J. Buras, Mikolaj Misiak

Several years ago, Stefan Pokorski, Manfred Muenz and us outlined a program for calculation of the NLO QCD corrections to the weak radiative B meson decay B -> X_s gamma. Very recently, just before the 60th birthday of Stefan Pokorski, this program has been formally completed. In the present paper, we summarize the existing results and discuss perspectives f

John P. Ralston, Pankaj Jain

For a long time people made the mistake of thinking the proton was understood. New experiments, ranging from form factors to deeply virtual Compton scattering, promise a new era of highly informative studies. Among the controversial topics of the future may be such basic features as the physical size of the proton, the role of quark orbital angular momentum,

H. Baer, J. Ferrandis, K. Melnikov, X. Tata

The value of the bottom quark mass at M_Z in the DR-bar scheme is an important input for the analysis of supersymmetric models with a large value of tan(beta). Conventionally, however, the running bottom quark mass extracted from experimental data is quoted in the MS-bar scheme at the bottom mass scale. We describe a two loop procedure for the conversion of

L. Favart

Results on Deeply Virtual Compton Scattering at HERA measured by the H1 and ZEUS Collaborations are presented. The cross section, measured for the first time, is reported for by H1 and ZEUS for $Q^2$ above a few GeV$^2$ in the low $x$ region. The measured cross section is discussed and compared to different predictions.

Murray Moinester

The electric alpha and magnetic beta pion Compton polarizabilities characterize the pion's deformation in the electromagnetic field of the gamma during gamma-pi Compton scattering. The chi_PT effective Lagrangian, using data from radiative pion beta decay, predicts the pion electric and magnetic polarizabilities alpha = -beta = 2.7 +- 0.4. The polarizabi

R. Aldrovandi, A. L. Barbosa

The cosmological constant Lambda, which has seemingly dominated the primaeval Universe evolution and to which recent data attribute a significant present-time value, is shown to have an algebraic content: it is essentially an eigenvalue of a Casimir invariant of the Lorentz group which acts on every tangent space. This is found in the context of de Sitter sp

B. Kleihaus, J. Kunz, F. Navarro-Lerida

We construct rotating hairy black holes in SU(2) Einstein-Yang-Mills theory. These stationary axially symmetric black holes are asymptotically flat. They possess non-trivial non-Abelian gauge fields outside their regular event horizon, and they carry non-Abelian electric charge. In the limit of vanishing angular momentum, they emerge from the neutral static

W. Chen

This paper is concerned with the two new boundary-type radial basis function collocation schemes, boundary knot method (BKM) and boundary particle method (BPM). The BKM is developed based on the dual reciprocity theorem, while the BPM employs the multiple reciprocity technique. Unlike the method of fundamental solution, the wto methods use the nonsingular ge

Ralf Schweimeier, Michael Schroeder

This paper defines an argumentation semantics for extended logic programming and shows its equivalence to the well-founded semantics with explicit negation. We set up a general framework in which we extensively compare this semantics to other argumentation semantics, including those of Dung, and Prakken and Sartor. We present a general dialectical proof theo

Masataka Tanaka, W Chen

This paper presents the first coupling application of the dual reciprocity BEM (DRBEM) and dynamic programming filter to inverse elastodynamic problem. The DRBEM is the only BEM method, which does not require domain discretization for general linear and nonlinear dynamic problems. Since the size of numerical discretization system has a great effect on the co

Samir Chopra, Aditya Ghose, Thomas Meyer

The axiom of recovery, while capturing a central intuition regarding belief change, has been the source of much controversy. We argue briefly against putative counterexamples to the axiom--while agreeing that some of their insight deserves to be preserved--and present additional recovery-like axioms in a framework that uses epistemic states, which encode pre

Samir Chopra, Johannes Heidema, Thomas Meyer

The introduction of explicit notions of rejection, or disbelief, into logics for knowledge representation can be justified in a number of ways. Motivations range from the need for versions of negation weaker than classical negation, to the explicit recording of classic belief contraction operations in the area of belief change, and the additional levels of e

N. Allen, T. Terriberry

We describe an efficient and fault-tolerant algorithm for distributed cyclic garbage collection. The algorithm imposes few requirements on the local machines and allows for flexibility in the choice of local collector and distributed acyclic garbage collector to use with it. We have emphasized reducing the number and size of network messages without sacrific

Paul G. Dommersnes, Yacov Kantor, Mehran Kardar

The interplay of topological constraints and Coulomb interactions in static and dynamic properties of charged polymers is investigated by numerical simulations and scaling arguments. In the absence of screening, the long-range interaction localizes irreducible topological constraints into tight molecular knots, while composite constraints are factored and se

G. Korniss, P. A. Rikvold, M. A. Novotny

It has been well established that spatially extended, bistable systems that are driven by an oscillating field exhibit a nonequilibrium dynamic phase transition (DPT). The DPT occurs when the field frequency is on the order of the inverse of an intrinsic lifetime associated with the transitions between the two stable states in a static field of the same magn

C. E. Aguiar, T. Kodama

The multiplicity distribution of particles in relativistic gases is studied in terms of Tsallis' nonextensive statistics. For an entropic index q>1 the multiplicity distribution is wider than the Poisson distribution with the same average number of particles, being similar to the negative binomial distribution commonly used in phenomenological analysis o

Marta Sales, Jean-Philippe Bouchaud, Felix Ritort

We study analytically and numerically the role of temperature shifts in the simplest model where the energy landscape is explicitely hierarchical, namely the Sinai model. This model has both attractive features (there are valleys within valleys in a strict self similar sense), but also one important drawback: there is no phase transition so that the model is

J. van Duijn, B. D. Gaulin, M. A. Lumsden, W. J. L. Buyers

Critical neutron scattering measurements have been performed on CsCo$_{0.83}$Mg$_{0.17}$Br$_3$, a dilute stacked triangular lattice (STL) Ising antiferromagnet (AF). A two component lineshape associated with the critical fluctuations appears at a temperature coincident with T$_{N1}$ observed in pure CsCoBr$_3$. Such scattering is indicative of fluctuations i

F. Ould Kaddour, D. Levesque

By using the Kirkwood formula, the friction coefficient of a solvated Brownian particle is determined from the integration on time of the autocorrelation function of the force that the solvent exerts on this particle. Extensive molecular dynamics simulations show that above a definite size of the studied systems the value of the integral defining the frictio

Ramandeep S. Johal

Within the nonextensive framework, it is shown that zeroth law of thermodynamics determines not only the mapping between Lagrange multipliers and intensive variables, but also the mapping between nonextensive and extensive entropy. The form of constraints decides the form of the extensive entropy, standard averages lead to Boltzmann-Shannon-Gibbs entropy whi

Alain Barrat, Emmanuel Trizac

We present molecular dynamics simulations of mono- or bidisperse inelastic granular gases driven by vibrating walls, in two dimensions (without gravity). Because of the energy injection at the boundaries, a situation often met experimentally, density and temperature fields display heterogeneous profiles in the direction perpendicular to the walls. A general

A. Nauen, I. Hapke-Wurst, F. Hohls, U. Zeitler

We investigate the noise properties of a GaAs-AlAs-GaAs tunneling structure with embedded self-assembled InAs quantum dots in the single-electron tunneling regime. We analyze the dependence of the relative noise amplitude of the shot noise on bias voltage. We observe a non-monotonic behaviour of the Fano-factor $α$ with an average value of $α\approx 0.8$ con

R. Masini, C. Artini, M. R. Cimberle, G. A. Costa

A systematic study on the synthesis of the Ru-1212 compound by preparing a series of samples that were annealed at increasing temperatures and then quenched has been performed. It results that the optimal temperature for the annealing lies around 1060-1065 C; a further temperature increase worsens the phase formation. Structural order is very important and t

A. P. F. Atman, Ronald Dickman

We construct the {\it quasi-stationary} (QS) probability distribution for the Domany-Kinzel stochastic cellular automaton (DKCA), a discrete-time Markov process with an absorbing state. QS distributions are derived at both the one- and two-site levels. We characterize the distribuitions by their mean, and various moment ratios, and analyze the lifetime of th

J. Karpinski, M. Angst, J. Jun, S. M. Kazakov

Single crystals of MgB2 with a size up to 1.5x0.9x0.2 mm3 have been grown with a high pressure cubic anvil technique. The crystal growth process is very peculiar and involves an intermediate nitride, namely MgNB9. Single crystals of BN and MgB2 grow simultaneously by a peritectic decomposition of MgNB9. Magnetic measurements in fields of 1-5 Oe show sharp tr

S. R. Krishnakumar, N. Shanthi, D. D. Sarma

We investigate the electronic structure of Nickel sulphide (NiS) in the millerite phase using electron spectroscopic measurements and band structure as well as model Hamiltonian calculations. While band structure calculations are found to be relatively more successful in describing the experimental valence band spectrum of this highly conducting phase compar

L. Viverit, S. Giorgini

We investigate the properties of a dilute boson-fermion mixture at zero temperature. The ground-state energy of the system is calculated to second order in the Bose-Fermi coupling constant. The Green's function formalism is applied to obtain results for the effect of Bose-Fermi interactions on the spectrum of phonon excitations, the momentum distribution

M. Moskalets, M. Buttiker

We consider the effect of an oscillating potential on the single-particle spectrum and the time-averaged persistent current of a one-dimensional phase-coherent mesoscopic ring with a magnetic flux. We show that in a ring with an even number of spinless electrons the oscillating potential has a strong effect on the persistent current when the excited side ban

T. Brandes, T. Vorrath

We investigate the influence of dissipation on one- and two-qubit rotations in coupled semiconductor quantum dots, using a (pseudo) spin-boson model with adiabatically varying parameters. For weak dissipation, we solve a master equation, compare with direct perturbation theory, and derive an expression for the `fidelity loss' during a simple operation th

T. Brandes, T. Vorrath

We compare standard perturbation theory with the polaron transformation for non-linear transport of electrons through a two-level system. For weak electron-phonon coupling and large bias, there is good agreement between both approaches. This regime has recently been explored in experiments in double quantum dots.

Akiyoshi shibuya, Yukio Saito, Hiroyuki Hyuga

The shape deformation of a three-dimensional axisymmetric vesicle with encapsulated filaments or impurities is analyzed by integrating a dissipation dynamics. This method can incorporate systematically the constraint of a fixed surface area and/or a fixed volume. The filament encapsulated in a vesicle is assumed to take a form of a rod or a ring so as to imi

Jordi Marcos, Antoni Planes, Lluís Mañosa, Amílcar Labarta

We have studied the effect of ageing within the miscibility gap on the electric, magnetic and thermodynamic properties of a non-stoichiometric Heusler Cu-Al-Mn shape-memory alloy, which undergoes a martensitic transition from a $bcc$-based ($β$-phase) towards a close-packed structure ($M$-phase). Negative magnetoresistance which shows an almost linear depend

Taisei Kaizoji, Stefan Bornholdt, Yoshi Fujiwara

The dynamics of a stock market with heterogeneous agents is discussed in the framework of a recently proposed spin model for the emergence of bubbles and crashes. We relate the log returns of stock prices to magnetization in the model and find that it is closely related to trading volume as observed in real markets. The cumulative distribution of log returns

J. Matsuno, T. Mizokawa, A. Fujimori, Y. Takeda

Iron perovskites CaFeO_3 and La_{0.33}Sr_{0.67}FeO_3 show charge disproportionation, resulting in charge-ordered states with Fe^{3+}:Fe^{5+} =1:1 and =2:1, respectively. We have made photoemission and unrestricted Hartree-Fock band-structure calculation of CaFeO_3 and compared it with La_{0.33}Sr_{0.67}FeO_3. With decreasing temperature, a gradual decrease o

Satya N. Majumdar, David S. Dean

We compute exactly the distribution of the occupation time in a discrete {\em non-Markovian} toy sequence which appears in various physical contexts such as the diffusion processes and Ising spin glass chains. The non-Markovian property makes the results nontrivial even for this toy sequence. The distribution is shown to have non-Gaussian tails characterized

S. Lee, T. Masui, H. Mori, Yu. Eltsev

We discuss the important aspects of synthesis and crystal growth of MgB2 under high pressure (P) and temperature (T) in Mg-B-N system, including the optimisation of P-T conditions for reproducible crystal growth, the role of liquid phases in this process, the temperature dependence of crystal size and the effect of growing instabilities on single crystals mo

Rangan Lahiri, Arvind, Anirban Sain

We present an insightful ``derivation'' of the Langevin equation and the fluctuation dissipation theorem in the specific context of a heavier particle moving through an ideal gas of much lighter particles. The Newton's Law of motion ($m{\ddot x}=F$) for the heavy particle reduces to a Langevin equation (valid on a coarser time scale) with the ass

Anatoli Polkovnikov, Subir Sachdev, S. M. Girvin

Motivated by recent experiments on trapped ultra-cold bosonic atoms in an optical lattice potential, we consider the non-equilibrium dynamic properties of such bosonic systems for a number of experimentally relevant situations. When the number of bosons per lattice site is large, there is a wide parameter regime where the effective boson interactions are str

M. Franz, Z. Tesanovic, O. Vafek

High-$T_c$ cuprates differ from conventional superconductors in three crucial aspects: the superconducting state descends from a strongly correlated Mott-Hubbard insulator, the order parameter exhibits d-wave symmetry and superconducting fluctuations play an all important role. We formulate a theory of the pseudogap state in the cuprates by taking the advant

Bradley S. Meyer

The r-process of nucleosynthesis requires a large neutron-to-seed nucleus ratio. This does not, however, that there be an excess of neutrons over protons. If the expansion of the material is sufficiently rapid and the entropy per nucleon is sufficiently high, the nucleosynthesis enters a heavy-element synthesis regime heretofore unexplored. In this extreme r

Heino Falcke, Peter Gorham

We discuss the possibilities of measuring ultra-high energy cosmic rays and neutrinos with radio techniques. We review a few of the properties of radio emission from cosmic ray air showers and show how these properties can be explained by coherent ``geosynchrotron'' emission from electron-positron pairs in the shower as they move through the geomagne

Sultana N. Nahar

Ab initio calculations including relativistic effects employing the Breit-Pauli R-matrix (BPRM) method are reported for fine structure energy levels and oscillator strengths upto n = 10 and 0.leq. l .leq.9 for 15 Li-like ions: C IV, N V, O VI, F VII, Ne VIII, Na IX, Mg X, Al XI, Si XII, S XIV, Ar XVI, Ca XIII, Ti XX, Cr XXII, and Ni XXVI. About one hundred b

Sultana N. Nahar

Most astrophysical plasmas entail a balance between ionization and recombination. We present new results from the powerful R-matrix method which yields in an ab initio manner: (I) self-consistent photoionization and recombination cross sections using identical wavefunction expansions, (II) unified e-ion recombination rates at all temperatures of interest, in

Sultana N. Nahar

Latest developments in theoretical computations since the international Opacity Project (OP), under the new the Iron Project (IP) and extensions, are described for applications to a variety of objects such as stellar atmospheres, nebulae, and active galactic nuclei. The primary atomic processes are: electron impact excitation (EIE), photoionization, electron

A. Sozzetti, S. Casertano, R. A. Brown, M. G. Lattanzi

(abridged) We present results from a detailed set of end-to-end numerical simulations of SIM narrow-angle astrometric measurements and data analysis to illustrate the enormous potential that SIM has for the discovery and characterization of planets outside the Solar System. Utilizing a template observing scenario, we quantify SIM sensitivity to single planet

Julianne J. Dalcanton, Rebecca A. Bernstein

(abridged) We present an analysis of B-R and R-K_s color maps for 47 late-type, edge-on, unwarped, bulgeless disk galaxies spanning a wide range of mass. The color maps show that the thin disks of these galaxies are embedded within a low surface brightness red envelope that is substantially thicker than the thin disk (a/b~4:1 vs a/b>8:1), extends to at least

T. Di Salvo, L. Stella

This paper surveys our current knowledge of the hard X-ray emission properties of old accreting neutron stars in low mass X-ray binaries. Hard X-ray components extending up to energies of a few hundred keV have been clearly detected in sources of both the Atoll and Z classes. The presence and characteristics of these hard components are discussed in relation

A. Veronig, B. Vrsnak, B. R. Dennis, M. Temmer

Based on a sample of 1114 flares observed simultaneously in hard X-rays (HXR) by the BATSE instrument and in soft X-rays (SXR) by GOES, we studied several aspects of the Neupert effect and its interpretation in the frame of the electron-beam-driven evaporation model. In particular, we investigated the time differences ($Δt$) between the maximum of the SXR em

Lee Hartmann

The remarkably filamentary spatial distribution of young stars in the Taurus molecular cloud has significant implications for understanding low-mass star formation in relatively quiescent conditions. The large scale and regular spacing of the filaments suggests that small-scale turbulence is of limited importance, which could be consistent with driving on la

T. W. Jones, Francesco Miniati, Dongsu Ryu, Hyesung Kang

Shocks are a ubiquitous consequence of cosmic structure formation, and they play an essential role in heating galaxy cluster media. Virtually all of the gas in clusters has been processed by one or more shocks of at least moderate strength. These are collisionless shocks, so likely sites for diffusive shock acceleration of high energy particles. We have carr

Unal Ertan, M. Ali Alpar

We suggest a new scenario to explain the outburst light curves of black hole soft X-ray transients together with the secondary maximum and the bump seen on their decay phases. Our explanations are based on the disk instability models considering the effect of X-ray irradiation. The scenario is consistent with the observed X-ray delays by a few days with resp

Thomas M. Brown

An 8 m successor to the Hubble Space Telescope (HST) would make incredible gains in the study of stellar populations, especially in the Local Group. If diffraction-limited at 0.5 microns, the "Next HST" could produce high-resolution imaging of faint sources over a wide field in 1 percent of the time needed with the HST. With these capabilities, photo

Thomas M. Brown, Henry C. Ferguson, Allen V. Sweigart, Randy A. Kimble

The compact elliptical galaxy M32 offers a unique testing ground for theories of stellar evolution. Because of its proximity, solar-blind UV observations can resolve the hot evolved stars in its center. Some of these late evolutionary phases are too rapid to study adequately in globular clusters, and their study in the Galactic field is often complicated by

M. J. Rioja, R. W. Porcas, J. -F. Desmurs, W. Alef

We describe, and present preliminary results from the analysis of 1.6 GHz VLBI observations, made in Cluster-Cluster mode between subgroups of antennas from the WSRT, VLA and MERLIN arrays. We observed for two 6-hour periods on consecutive days, simultaneously monitoring 4 compact radio sources with angular separations ranging from ~1 to 9 degrees. The data

Tsutomu TAKAMIYA, Yoshiaki SOFUE

We present an iteration method to derive exact rotation curves (RC) of spiral galaxies from observed position-velocity diagrams (PVD), which comprises the following procedure. An initial rotation curve, RC0, is adopted from an observed PV diagram (PV0), obtained by any simple method such as the peak-intensity method. Using this rotation curve and an observed

Qiusheng Gu Jiehao Huang

We present a compilation of radio, infrared, optical and hard X-ray (2-10kev) data for a sample of 90 Seyfert 2 galaxies(Sy2s) with spectropolarimetric observations (41 Sy2s with detection of polarized broad lines (PBL) and 49 without PBL). Compared to Sy2s without PBL, Sy2s with PBL tend to be earlier-type spirals, and show warmer mid-infrared color and sig

L. Olmi, L. Testi

We have mapped the large-scale structure of the Serpens cloud core using moderately optically thick (13CO(1--0) and CS(2--1)) and optically thin tracers (C18O(1--0), C34S(2--1), and N2H+(1--0)), using the 16-element focal plane array operating at a wavelength of 3mm at the Five College Radio Astronomy Observatory. Our main goal was to study the large-scale d

Aake Nordlund

A magnetically dominated plasma driven by motions on boundaries at which magnetic field lines are anchored is forced to dissipate the work being done upon it, no matter how small the electrical resistivity. Numerical experiments have clarified that dissipation is achieved through the formation of a hierarchy of electrical current sheets. The probability dist

Laird A. Thompson, Scott W. Teare, Samuel L. Crawford, Robert W. Leach

Laser guide star systems based on Rayleigh scattering require some means to deal with the flash of low altitude laser light that follows immediately after each laser pulse. These systems also need a fast shutter to isolate the high altitude portion of the focused laser beam to make it appear star-like to the wavefront sensor. We describe how these tasks are

S. M. Ord, M. Bailes, W. van Straten

We have obtained an HI absorption spectrum of the relativistic binary PSR J1141-6545 and used it to constrain the distance to the system. The spectrum suggests that the pulsar is at, or beyond, the tangent point, estimated to be at 3.7 kpc. PSR J1141-6545 offers the promise of stringent tests of General Relativity (GR) by comparing its observed orbital perio

Max Tegmark

Nerd abstract: Observational constraints on spacetime are reviewed, focusing on how the underlying physics (dark matter, dark energy, gravity) can be tested rather than assumed. Popular abstract: Space is not a boring static stage on which events unfold over time, but a dynamic entity with curvature, fluctuations and a rich life of its own which is a booming

A. De Rujula

The cannonball model of GRBs is very overt (and, thus, falsifiable) in its hypothesis and results: all the considerations I review are based on explicit analytical expressions derived, in fair approximations, from first principles. The model provides a good description of all the data on all GRBs of known redshift, has made correct predictions, and is unprec

J. Groeneveld, R. Klages

We consider a simple model of particle transport on the line defined by a dynamical map F satisfying F(x+1) = 1 + F(x) for all x in R and F(x) = ax + b for |x| < 0.5. Its two parameters a (`slope&#39;) and b (`bias&#39;) are respectively symmetric and antisymmetric under reflection x -> R(x) = -x. Restricting ourselves to the chaotic regime |a| > 1 and there

K. Jimmy Juge, Julius Kuti, Colin Morningstar

Using advanced lattice methods in Quantum Chromodynamics, three distinct scales are established in the excitation spectrum of the gluon field around a static quark-antiquark pair as the color source separation R is varied. On the shortest length scale, the excitations are consistent with states created by local gluon field operators arising from a multipole

J. M. Diego, S. H. Hansen, J. Silk

We study the effect of imperfect subtraction of the Sunyaev-Zel&#39;dovich effect (SZE) using a robust and non-parametric method to estimate the SZE residual in the Planck channels. We include relativistic corrections to the SZE, and present a simple fitting formula for the SZE temperature dependence for the Planck channels. We show how the relativistic corr

S. Jeon, J. Jalilian-Marian, I. Sarcevic

We present results for the large-$p_T$ inclusive $π^0$ production in p-p and A-A collisions at RHIC and LHC energies. We include the full next-to-leading order radiative corrections, $O(α_s^3)$, and nuclear effects such as parton energy loss and nuclear shadowing. We find the next-to-leading order corrections and the parton energy loss effect to be large and

Daniele Oriti, Hendryk Pfeiffer

We propose a spin foam model for pure gauge fields coupled to Riemannian quantum gravity in four dimensions. The model is formulated for the triangulation of a four-manifold which is given merely combinatorially. The Riemannian Barrett--Crane model provides the gravity sector of our model and dynamically assigns geometric data to the given combinatorial tria

F. Ellinghaus

We report the first observation of an azimuthal asymmetry in the hard electroproduction of real photons with respect to the charge of the incoming lepton beam. The asymmetry is attributed to the interference between the Bethe-Heitler process and the deeply-virtual Compton scattering process, which gives access to the latter at the amplitude level. This proce

T. Briant, P. F. Cohadon, M. Pinard, A. Heidmann

We describe an experiment in which the quadratures of the position of an harmonically-bound mirror are observed at the attometer level. We have studied the Brownian motion of the mirror, both in the free regime and in the cold-damped regime when an external viscous force is applied by radiation pressure. We have also studied the thermal-noise squeezing when

Ivan Tyukin, Cees van Leeuwen, Danil Prokhorov

Superposition of sigmoid function over a finite time interval is shown to be equivalent to the linear combination of the solutions of a linearly parameterized system of logistic differential equations. Due to the linearity with respect to the parameters of the system, it is possible to design an effective procedure for parameter adjustment. Stability propert