July 2000 arXiv papers — page 15

Marie E. Machacek, Greg L. Bryan, Tom Abel

We present results from three-dimensional hydrodynamic simulations of the high redshift collapse of pregalactic clouds including feedback effects from a soft H2 photodissociating UV radiation field. The simulations use an Eulerian adaptive mesh refinement technique to follow the nonequilibrium chemistry of nine chemical species with cosmological initial cond

Donald Lynden-Bell

Although magnetic fields in interstellar matter were postulated almost fifty years ago, magnetohydrodynamic theory was then much hampered by our inability to see what the magnetic field configurations were like and, after a decade of innovative development, cynics, not without some justification, began to claim that anything can happen when magnetism and an

Andrew W. Blain

The Planck Surveyor cosmic microwave background (CMB) imaging mission will make very sensitive maps of the whole sky at microwave, millimetre (mm) and sub-mm wavelengths. The steep source counts expected in the highest frequency Planck bands are likely to be associated with a strong magnification bias, and so the fraction of galaxies magnified by a factor of

Chul-Sung Choi, Tadayasu Dotani, Insu Yi, ChulHee Kim

We present results from analysis of the X-ray archive data of MCG-2-58-22, acquired with ROSAT from 1991 to 1993 and with ASCA from 1993 to 1997. By analyzing light curves, we find that MCG-2-58-22 shows a clear time variability in X-ray flux. The time scales of the variations range widely from about 1000 s to more than years. Among the variations, a flare-l

A. Kawachi, Y. Hayami, J. Jimbo, S. Kamei

A new imaging atmospheric Cherenkov telescope (CANGAROO-II) with a light-weight reflector has been constructed. Light, robust, and durable mirror facets of containing CFRP (Carbon Fiber Reinforced Plastic) laminates were developed for the telescope. The attitude of each facet can be adjusted by stepping motors. In this paper, we describe the design, manufact

H. Roussel, R. Sadat, A. Blanchard

We have analyzed the properties of a sample of 33 groups and clusters of galaxies and examine the baryon content to check for trends over a decade in temperature down to 1 keV. We examine the relative contribution of galaxies and ICM to baryons in clusters through the gas-to-stellar mass ratio and find that the typical stellar contribution to the baryonic ma

E. L. Afraimovich, N. P. Perevalova, A. V. Plotnikov, A. M. Uralov

We investigate the form and dynamics of shock-acoustic waves generated by earthquakes. We use the method for detecting and locating the sources of ionospheric impulsive disturbances, based on using data from a global network of receivers of the GPS navigation system and requiring no a priori information about the place and time of associated effects. The pra

Heath B. O'Connell

The Stanford Linear Accelerator Center (SLAC) and Deutsches Elektronen Synchrotron (DESY) libraries have been comprehensively cataloguing the High Energy Particle Physics (HEP) literature online since 1974. The core database, SPIRES-HEP, now indexes over 400,000 research articles, with almost 50% linked to fulltext electronic versions (this site now has over

Riazuddin

By a simple extension of the standard model in which ($e-\mu -\tau $) universality is not conserved, we present a scenario within the framework of see-saw mechanism in which the neutrino mass matrix is strictly off-diagonal in the flavor basis. We show that a version of this scenario can accomodate the atmospheric $\nu_\mu -\nu_\tau $ neutrino oscillations a

Hirosi Ooguri, J. Rahmfeld, Harlan Robins, Jonathan Tannenhauser

The AdS/CFT correspondence identifies the coordinates of the conformal boundary of anti-de Sitter space with the coordinates of the conformal field theory. We generalize this identification to theories formulated in superspace. As an application of our results, we study a class of Wilson loops in N=4 SYM theory. A gauge theory computation shows that the expe

W. Hollik, E. Kraus, D. Stöckinger

The renormalization of supersymmetric Yang-Mills theories with soft supersymmetry breaking is presented using spurion fields for introducing the breaking terms. It is proven that renormalization of the fields and parameters in the classical action yields precisely the correct counterterms to cancel all divergences. In the course of the construction of higher

M. E. J. Newman, S. H. Strogatz, D. J. Watts

Recent work on the structure of social networks and the internet has focussed attention on graphs with distributions of vertex degree that are significantly different from the Poisson degree distributions that have been widely studied in the past. In this paper we develop in detail the theory of random graphs with arbitrary degree distributions. In addition

Joel R. Primack

The cosmological parameters that I emphasize are the age of the universe $t_0$, the Hubble parameter $H_0 \equiv 100 h$ km s$^{-1}$ Mpc$^{-1}$, the average matter density $Ω_m$, the baryonic matter density $Ω_b$, the neutrino density $Ω_ν$, and the cosmological constant $Ω_Λ$. The evidence currently favors $t_0 \approx 13$ Gyr, $h \approx 0.65$, $Ω_m \approx

E. Gourgoulhon, P. Grandclement, K. Taniguchi, J. -A. Marck

We present a numerical method to compute quasiequilibrium configurations of close binary neutron stars in the pre-coalescing stage. A hydrodynamical treatment is performed under the assumption that the flow is either rigidly rotating or irrotational. The latter state is technically more complicated to treat than the former one (synchronized binary), but is e

G. Brunthaler, A. Prinz, G. Bauer, V. M. Pudalov

The temperature and density dependence of the phase coherence time $τ_ϕ$ in high-mobility silicon inversion layers was determined from the magnetoresistivity due to weak localization. The upper temperature limit for single-electron quantum interference effects was delineated by comparing $τ_ϕ$ with the momentum relaxation time $τ$. A comparison between the d

C. S. Lam, Gregory Mahlon

We extend the McLerran-Venugopalan model for the gluon distribution functions of very large nuclei to larger values of the longitudinal momentum fraction xF. Because gluons with larger values of xF begin to resolve the longitudinal structure of the nucleus, we find that it is necessary to set up a fully three-dimensional formalism for performing the calculat

Zhi-zhong Xing

The significance of final-state interactions in B_d-->ππdecays is phenomenologically demonstrated by taking elastic ππ--ππand inelastic ππ--D\bar{D} rescattering effects into consideration. We find that the present experimental data on B^0_d-->π^+π^- can well be understood in this approach without fine-tuning of the input parameters, and large CP-violating a

A. Gal, E. Friedman, C. J. Batty

Recent measurements of very low-energy ($p_{L}<100$ MeV/c) $\bar p$ annihilation on light nuclei reveal apparent suppression of annihilation upon increasing the atomic charge $Z$ and mass number $A$. Using $\bar p$-nucleus optical potentials $V_{\rm opt}$, fitted to $\bar p$-atom energy-shifts and -widths, we resolve this suppression as due to the strong eff

A. Freitas, S. Heinemeyer, W. Hollik, W. Walter

The computation of the correction Δr in the W-Z mass correlation, derived from muon decay, is described at the two-loop level in the Standard Model. Technical aspects which become relevant at this level are studied, e.g. gauge-parameter independent mass renormalization, ghost-sector renormalization and the treatment of γ_5. Exact results for Δr and the W mas

Valentin D. Ivanov, George H. Rieke, Christopher E. Groppi, Almudena Alonso-Herrero

We use the CO band at 2.3 micron to constrain the populations of young stars in the central regions of Seyfert galaxies. We report new CO band spectroscopy of 46 Seyfert galaxies. In most cases, the observed CO indices appear diluted by the presence of a non-stellar component (most likely, warm dust surrounding the active nucleus). We used JHKL aperture phot

T. Kawai, K. Shibata, I. Tanaka

In extended new general relativity, which is formulated as a reduction of $\bar{Poincaré} $gauge theory of gravity whose gauge group is the covering group of the Poincaré group, we study the problem of whether the total energy-momentum, total angular momentum and total charge are equal to the corresponding quantities of the gravitational source. We examine t

A. J. Barger, L. L. Cowie, R. F. Mushotzky, E. A. Richards

With recent Chandra observations, at least 60% of the 2-10 keV background is now resolved into discrete sources. Here we present deep optical, NIR, submm, and 20 cm (radio) images, as well as high-quality optical spectra, of a complete sample of 20 hard X-ray sources in a deep Chandra observation of the SSA13 field. The thirteen I<23.5 galaxies have redshift

Xiwen Zhu, Ximing Fang, Mang Feng, Fei Du

The highly structured search algorithm proposed by Hogg[Phys.Rev.Lett. 80,2473(1998)] is implemented experimentally for the 1-SAT problem in a single search step by using nuclear magnetic resonance technique with two-qubit sample. It is the first demonstration of the Hogg&#39;s algorithm, and can be readily extended to solving 1-SAT problem for more qubits i

E. L. Afraimovich, E. A. Kosogorov, N. P. Perevalova, A. V. Plotnikov

This paper is concerned with the form and dynamics of shock-acoustic waves (SAW) generated during rocket launchings. We have developed a method for determining SAW parameters (including angular characteristics of the wave vector, and the SAW phase velocity, as well as the direction towards the source) using GPS-arrays whose elements can be chosen out of a la

J. R. Mureika

A quasi-physical model (having both physical and mathematical roots) of sprint performances is presented, accounting for the influence of drag modification via wind and altitude variations. The race time corrections for both men and women sprinters are discussed, and theoretical estimates for the associated drag areas are presented. The corrections are consi

Gerald L. Fitzpatrick

A new internal description of fundamental fermions (quarks and leptons), based on a matrix-generalization (F) of the scalar fermion-number f, predicts that only three families of quarks and leptons, and their associated neutrinos (nu_e, nu_mu and nu_tau), exist. Moreover, this description places important topological constraints on neutrino mixing. For examp

Gerald L. Fitzpatrick

An &#34;analytic continuation&#34; of a Hermitian matrix representing the conventional fermion-number operator, leads to a new, and unconventional, internal description of quarks and leptons. This phenomenological description, unlike the conventional standard-model description, is capable of explaining, among other things, why there are just three families o

A. Kim, F. Cattani, D. Anderson, M. Lisak

It is shown that penetration of relativistically intense laser light into an overdense plasma, accessible by self-induced transparency, occurs over a finite length only. The penetration length depends crucially on the overdense plasma parameter and increases with increasing incident intensity after exceeding the threshold for self-induced transparency. Exact

O. Scavenius, A. Mocsy, I. N. Mishustin, D. H. Rischke

We investigate the chiral phase transition at nonzero temperature $T$ and baryon-chemical potential $μ_B$ within the framework of the linear sigma model and the Nambu-Jona-Lasinio model. For small bare quark masses we find in both models a smooth crossover transition for nonzero $T$ and $μ_B=0$ and a first order transition for T=0 and nonzero $μ_B$. We calcu

J. E. Garcia-Ramos, J. M Arias, P. Van Isacker

Double-$γ$ vibrations in deformed nuclei are analyzed in the context of the interacting boson model. A simple extension of the original version of the model towards higher-order interactions is required to explain the observed anharmonicities of nuclear vibrations. The influence of three- and four-body interactions on the moments of inertia of ground- and $γ

H. J. Woertche

Our collaboration has set up a focal plane detection system and a focal plane polarimeter at the large acceptance Big-Bite Spectrometer at AGOR. The detector systems are equipped with a high performance readout and online data processing system, which allows polarization transfer and charge transfer measurements at extreme forward angles with high precision.

Nils Berglund, Turgay Uzer

We treat the classical dynamics of the hydrogen atom in perpendicular electric and magnetic fields as a celestial mechanics problem. By expressing the Hamiltonian in appropriate action-angle variables, we separate the different time scales of the motion. The method of averaging then allows us to reduce the system to two degrees of freedom, and to classify th

Bob Rink

The symmetry and resonance properties of the Fermi Pasta Ulam chain with periodic boundary conditions are exploited to construct a near-identity transformation bringing this Hamiltonian system into a particularly simple form. This `Birkhoff-Gustavson normal form&#39; retains the symmetries of the original system and we show that in most cases this allows us

Olivier Grandjean, Arthur Jaffe, Jon Tyson

We prove twist positivity and positivity of the pair correlation function for combined spatial and internal symmetries of free bosonic Lagrangians. We work in a general setting, extending the results obtained in Twist Positivity [1].

M. Mekhfi

In a recent paper we investigated the internal space of Bessel functions associated with their orders. We found a formula (new) unifying Bessel functions of integer and of real orders. In this paper we study the deformed exterior derivative system $H=d_λ$ on the puctured plane as a tentative to understand the origin of the formula and find that indeed simila

Nathan M. Dunfield

For a 3-manifold M, McMullen derived from the Alexander polynomial of M a norm on H^1(M, R) called the Alexander norm. He showed that the Thurston norm on H^1(M, R), which measures the complexity of a dual surface, is an upper bound for the Alexander norm. He asked if these two norms were equal on all of H^1(M,R) when M fibers over the circle. Here, I give e

William G. McCallum

In this paper we prove Greenberg&#39;s pseudo-null conjecture for the field of p-th roots of unity in the case that p exactly divides the class number and the index of the global units in the local units. We also generalize to the case of multiple Z_p-extensions a theorem of Iwasawa on the Kummer extension of the cyclotomic Z_p-extension generated by p-power

Maja Volkov

This paper is devoted to the study of the $\ell$-adic representations of the absolute Galois group $G$ of ${\mathbb Q}_p$, $p\geq 5$, associated to an elliptic curve over ${\mathbb Q}_p$, as $\ell$ runs through the set of all prime numbers (including $\ell =p$, in which case we use the theory of potentially semi-stable $p$-adic representations). For each pri

Aaron Bertram

A simple corollary of the localization theorem (due to the author and, independently, to Lian-Liu-Yau) is applied to several problems in enumerative geometry. New formulas for Schubert calculus on flag manifolds, due to Kong, and a new reconstruction theorem for genus-zero Gromov-Witten invariants, due to Bertram-Kley, are discussed, as well as some simple f

Aaron Bertram, Holger P. Kley

New relations among the genus-zero Gromov-Witten invariants of a complex projective manifold $X$ are exhibited. When the cohomology of $X$ is generated by divisor classes and classes ``with vanishing one-point invariants,&#39;&#39; the relations determine many-point invariants in terms of one-point invariants.

D. O. Gunter, H. G. Kaper, G. K. Leaf

This article is concerned with the integration of the time-dependent Ginzburg--Landau (TDGL) equations of superconductivity. Four algorithms, ranging from fully explicit to fully implicit, are presented and evaluated for stability, accuracy, and compute time. The benchmark problem for the evaluation is the equilibration of a vortex configuration in a superco

Boris Shoikhet

We prove that the Kontsevich integrals (in the sense of the formality theorem) of all even wheels are equal to zero. We deduce this theorem from the result of \cite{FSh} on the deformation quantization with traces.

Tom H. Koornwinder

This paper gives some further details of proofs of some theorems related to the quantum dynamical Yang-Baxter equation. This mainly expands proofs given in &#34;Lectures on the dynamical Yang-Baxter equation&#34; by P. Etingof and O. Schiffmann, math.QA/9908064. This concerns the intertwining operator, the fusion matrix, the exchange matrix and the differenc

F. Bastianelli, O. Corradini, P. van Nieuwenhuizen

We use dimensional regularization to evaluate quantum mechanical path integrals in arbitrary curved spaces on an infinite time interval. We perform 3-loop calculations in Riemann normal coordinates, and 2-loop calculations in general coordinates. It is shown that one only needs a covariant two-loop counterterm (V_{DR} = R/8) to obtain the same results as obt

S. Andrea, A. Sotomayor, A. Restuccia

An extension of the Super KdV integrable system in terms of operator valued functions is obtained. Following the ideas of Gardner, a general algebraic approach for finding the infinitely many conserved quantities of integrable systems is presented. The approach is applied to the above described system and infinitely many conserved quantities are constructed.

J. Lukierski, P. C. Stichel, W. J. Zakrzewski

We consider the gauging of space translations with time-dependent gauge functions. Using fixed time gauge of relativistic theory, we consider the gauge-invariant model describing the motion of nonrelativistic particles. When we use gauge-invariant nonrelativistic velocities as independent variables the translation gauge fields enter the equations through a d

Ulf Lindstrom, Harald Svendsen

In this article we study limits of models that contain a dimensionful parameter such as the mass of the relativistic point-particle. The limits are analogous to the massless limit of the particle and may be thought of as high energy limits. We present the ideas and work through several examples in a (hopefully) pedagogical manner. Along the way we derive sev

Elena Gubankova

Flow equations method of continuous unitary transformations is used to eliminate the minimal quark-gluon interaction in the light-front quantized QCD Hamiltonian. The coupled differential equations in the two lowest Fock sectors correspond to the renormalization of the light-front gluon mass and the generation of effective quark-antiquark interaction. The in

Carl H. Albright, S. M. Barr

A complete set of Higgs and matter superfields is introduced with well-defined SO(10) properties and U(1) \times Z_2 \times Z_2 family charges from which the Higgs and Yukawa superpotentials are constructed. The Higgs fields solve the doublet-triplet splitting problem, while the structures of the four Dirac fermion mass matrices obtained involve just six eff

B. Pasquini, D. Drechsel, M. Gorchtein, A. Metz

A dispersion relation formalism for the virtual Compton scattering (VCS) reaction on the proton is presented, which for the first time allows a dispersive evaluation of 4 generalized polarizabilities at a four-momentum transfer $Q^2 \leq$ 0.5 GeV$^2$. The dispersive integrals are calculated using a state-of-the-art pion photo- and electroproduction analysis.

George D. Tsibidis

A non-covariant but approximately relativistic two-body wave equation (Breit equation) describing the quantum mechanics of two fermions interacting with one another through a potential containing scalar, pseudoscalar and vector parts is presented. After expressing the sixteen component two-body wavefunction in terms of a radial and an angular function by mea

S. Catani, M. Grazzini

We study the soft limit of one-loop QCD amplitudes and we derive the process-independent factorization formula that controls the singular behaviour in this limit. This is obtained from the customary eikonal factorization formula valid at tree (classical) level by introducing a generalized soft-gluon current that embodies the quantum corrections. We compute t

S. Kuhlmann, J. Huston, J. Morfin, F. Olness

Reliable knowledge of parton distributions at large x is crucial for many searches for new physics signals in the next generation of collider experiments. Although these are generally well determined in the small and medium x range, it has been shown that their uncertainty grows rapidly for x>0.1. We examine the status of the distributions in light of new qu

S. Kuhlmann, J. Huston, J. Morfin, F. Olness

Reliable knowledge of parton distributions at large x is crucial for many searches for new physics signals in the next generation of collider experiments. Although these are generally well determined in the small and medium x range, it has been shown that their uncertainty grows rapidly for x>0.1. We examine the status of the gluon and quark distributions in

Debajyoti Choudhury, Dilip Kumar Ghosh

We study the pair-production and decay of right handed selectrons within a Gauge Mediated Supersymmetry Breaking Model in polarised $e^-e^-$ interaction. Detailed analyses of the possible signals and backgrounds are performed for a few selected points in the parameter space. A judicious choice for polarisation of the initial electron beam helps eliminate alm

H. Arthur Weldon

The thermal Wightman functions for free, massless particles of spin 0, 1/2, 1, 3/2, and 2 are computed directly in coordinate space by solving the appropriate differential equation and imposing the Kubo-Martin-Schwinger condition. The solutions are valid for real, imaginary, or complex time. The Wightman functions for spin 1 gauge bosons and for spin 2 gravi

Zhi-zhong Xing

Within the framework of three lepton families I present a transparent analytical relationship between the neutrino mixing and CP-violating parameters in vacuum and thos in matter. Such a model- and parametrization-independent result will be particularly useful to recast the fundamental lepton flavor mixing matrix from the future long-baseline neutrino experi

S. Fajfer, P. Singer

The $ΔS = 2$ $b \to \bar d ss$ transition proceeds via the box - diagram in the Standard Model with a branching ratio calculated to be below $10^{-11}$, thus providing an appropriate testing ground for physics beyond the Standard Model. We analyze the $ΔS = 2$ two - body $B^- \to K^{*-} \bar K^{*0}$, $B^- \to K^- \bar K^{0}$, $B^- \to K^{*-} \bar K^{0}$ and

D. Ebert, M. Nagy, M. K. Volkov, V. L. Yudichev

Ground-state scalar isoscalar mesons and a scalar glueball are described in a U(3)xU(3) chiral quark model of the Nambu--Jona-Lasinio (NJL) type with &#39;t Hooft interaction. The latter interaction produces singlet-octet mixing in the scalar and pseudoscalar sectors. The glueball is introduced into the effective meson Lagrangian as a dilaton on the base of

M. V. Savina, S. V. Shmatov, N. V. Slavin, P. I. Zarubin

The global observable distributions of nucleus-nucleus collisions at high energy are studied. It is shown that these distributions are sensitive to interaction dynamics and can be used to investigate the evolution of dense nuclear matter. At the LHC energy scale ($\sqrt{s_{NN}}=5$ TeV in the heavy ion mode), a central bump over pseudorapidity plateau in the

M. V. Savina, S. V. Shmatov, N. V. Slavin, P. I. Zarubin

HIJING generator simulation of nucleus-nucleus collisions at ultrarelativistic energies are presented. Is shown, that the global characteristics of nucleus-nucleus collisions, such as of distribution of a charge multiplicity, total and electromagnetic transverse energy over pseudorapidity are rather sensitive to some predictions of formation models of high-e

Daisuke Jido, Atsushi Hosaka, Makoto Oka

Double meson production of the eta and pion at the threshold region is investigated in order to determine chiral property of the nucleon. The eta can be used as a probe for the negative parity nucleon $N^* \equiv N^*(1535)$ produced in the intermediate state. The coupling of the low energy pion in the final state is then used to extract the sign of the Yukaw

Constantinos Pallis

The cosmological relic density of a Bino-like Lightest Supersymmetric Particle is calculated in the framework of the Minimal Supersymmetric Standard Model. We include annihilation and coannihilation effects of the Bino with the lightest stau and with the other sleptons, which happen to have comparable masses with it. Coannihilation turns out to be crucial fo

Dmitri Antonov

In this talk, various approaches to the problem of evaluation of the field strength correlators in the SU(3)-gluodynamics, which play the major role in the Stochastic Vacuum Model, are reviewed. This is done in the framework of the effective Abelian-projected theories under the various assumptions implied on the properties of the ensemble of Abelian-projecte

R. Aloisio, V. Azcoiti, G. Di Carlo, A. Galante

Unquenched lattice SU(2) is studied at nonzero chemical potential in the strong coupling limit. The topic of diquark condensation is addressed analyzing the probability distribution function of the diquark condensate. We present results at zero external source without using any potentially dangerous extrapolation procedure. We find strong evidences for a (hi

Harold G. Evans

Higgs hunting is a world-wide sport and the Tevatron is set to become the next field of play when Run II starts in March 2001. To set the stage, we summarize results of searches for standard and non-standard Higgs bosons by CDF and Dzero in Run I at the Tevatron. Progress has been made in quantifying the requirements on the Tevatron Collider and on the upgra

N H Brook

The distribution of the azimuthal angle for the charged hadrons has been studied in the hadronic centre-of-mass system for neutral current deep inelastic positron-proton scattering at HERA. Measurements of the dependence of the moments of this distribution on the transverse momenta of the charged hadrons are presented. Asymmetries that can be unambiguously a

V. V. Kassandrov

The generalized Cauchy-Riemann equations (GCRE) in biquaternion algebra appear to be Lorentz-invariant. The Laplace equation is in this case replaced by a nonlinear (complexified) eikonal equation. GCRE contain the 2-spinor and the gauge structures, and their integrability conditions take the form of free-source Maxwell and Yang-Mills equations. For the valu

V. V. Kassandrov, V. N. Trishin

Foundations of algebrodynamics based on earlier proposed equations of biquaternionic holomorphy are briefly expounded. Free Maxwell and Yang-Mills Eqs. are satisfied identically on the solutions of primary system which is also related to the Eqs. of shear-free null congruences (SFC), and through them - to the Einstein-Maxwell electrovacuum system. Kerr theor

Christian Glasser, Lane A. Hemaspaandra

We discuss the history and uses of the parallel census technique---an elegant tool in the study of certain computational objects having polynomially bounded census functions. A sequel will discuss advances (including Cai, Naik, and Sivakumar [CNS95] and Glasser [Gla00]), some related to the parallel census technique and some due to other approaches, in the c

David Graff, Steven Bird

This paper discusses the challenges that arise when large speech corpora receive an ever-broadening range of diverse and distinct annotations. Two case studies of this process are presented: the Switchboard Corpus of telephone conversations and the TDT2 corpus of broadcast news. Switchboard has undergone two independent transcriptions and various types of ad

Steven Bird, Peter Buneman, Wang-Chiew Tan

The multidimensional, heterogeneous, and temporal nature of speech databases raises interesting challenges for representation and query. Recently, annotation graphs have been proposed as a general-purpose representational framework for speech databases. Typical queries on annotation graphs require path expressions similar to those used in semistructured quer

Steven Bird, David Day, John Garofolo, John Henderson

We describe a formal model for annotating linguistic artifacts, from which we derive an application programming interface (API) to a suite of tools for manipulating these annotations. The abstract logical model provides for a range of storage formats and promotes the reuse of tools that interact through this API. We focus first on ``Annotation Graphs,&#39;&#

Erik D. Demaine, Martin L. Demaine, Anna Lubiw, Joseph O&#39;Rourke

We investigate how to make the surface of a convex polyhedron (a polytope) by folding up a polygon and gluing its perimeter shut, and the reverse process of cutting open a polytope and unfolding it to a polygon. We explore basic enumeration questions in both directions: Given a polygon, how many foldings are there? Given a polytope, how many unfoldings are t

Jakub Zavrel, Walter Daelemans

This paper describes a new method, Combi-bootstrap, to exploit existing taggers and lexical resources for the annotation of corpora with new tagsets. Combi-bootstrap uses existing resources as features for a second level machine learning module, that is trained to make the mapping to the new tagset on a very small sample of annotated corpus material. Experim

R. Schweiger, S. Hoelzer, J. Dudeck

Data modeling is one of the most difficult tasks in application engineering. The engineer must be aware of the use cases and the required application services and at a certain point of time he has to fix the data model which forms the base for the application services. However, once the data model has been fixed it is difficult to consider changing needs. Th

Mickael Antoni, Haye Hinrichsen, Stefano Ruffo

We study the Hamiltonian Mean Field (HMF) model, a system of $N$ fully coupled particles, in the microcanonical ensemble. We use the previously obtained free energy in the canonical ensemble to derive entropy as a function of energy, using Legendre transform techniques. The temperature-energy relation is found to coincide with the one obtained in the canonic

R. Kannan, K. P. Ramesh, J. Ramakrishna

We report here the results of $^1$H NMR spin-lattice relaxation time (T$_1$) studies in Glycine phosphite which is a ferroelectric below 224 K. The experiments have been carried out in the temperature range from 200 K to 419 K and at two Larmour frequencies of 11.40MHz and 23.56 MHz. We have noticed a Larmour frequency dependence on the high temperature side

John A. Vaccaro, Ole Steuernagel, Ben Lorimer

We investigate the excited stationary states of Bose-Einstein condensates trapped in harmonic potentials. We derive simple analytical approximations of the first few eigenstates of the associated time-independent one-dimensional Gross-Pitaevskii equation and their energies. Our results are excited state generalizations of the Thomas-Fermi approximation of th

H. C. Rae, J. A. F. Heimel, A. C. C. Coolen

We study the dynamics of on-line learning in large perceptrons, for the case of training sets with a structural bias of the input vectors, by deriving exact and closed macroscopic dynamical laws using non-equilibrium statistical mechanical tools. In sharp contrast to the more conventional theories developed for homogeneously distributed or only weakly biased

M. v. Zimmermann, C. S. Nelson, J. P. Hill, Doon Gibbs

We present the results of a systematic x-ray scattering study of the charge and orbital ordering in the manganite series Pr$_{1-x}$Ca$_x$MnO$_3$ with $x$=0.25, 0.4 and 0.5. The temperature dependence of the scattering at the charge and orbital wavevectors, and of the lattice constants, was characterized throughout the ordered phase of each sample. It was fou

A. Lang, C. N. Likos, M. Watzlawek, H. Lowen

We study the structural and thermodynamic properties of a model of point particles interacting by means of a Gaussian pair potential first introduced by Stillinger [Stillinger F H 1976 J. Chem. Phys. 65, 3968]. By employing integral equation theories for the fluid state and comparing with Monte Carlo simulation results, we establish the limits of applicabili

S. Wessel, B. Normand, M. Sigrist, S. Haas

We consider doping of non-magnetic impurities in the spin-1/2, 1/5-depleted square lattice. This structure, whose undoped phase diagram offers both magnetically ordered and spin-liquid ground states, is realized physically in CaV_4O_9. Doping into the ordered phase results in a progressive loss of order, which becomes complete at the percolation threshold. B

S. Atzkern, M. Knupfer, M. S. Golden, J. Fink

We have measured the energy and momentum dependent loss function of Li_2CuO_2 single crystals by means of electron energy-loss spectroscopy in transmission. Using the same values for the model parameters, the low-energy features of the spectrum as well as published Cu 2p_(3/2) x-ray photoemission data of Li_2CuO_2 are well described by a cluster model that c

R. A. J. van Elburg, K. Schoutens

The non-Fermi liquid physics at the edge of fractional quantum Hall systems is described by specific chiral Conformal Field Theories with central charge c=1. The charged quasi-particles in these theories have fractional charge and obey a form of fractional statistics. In this paper we study form factors, which are matrix elements of physical (conformal) oper

Ryoichi Yamamoto, Akira Onuki

Molecular dynamics simulations were performed for a polymer melt. In quiescent states, the inter-chain interaction energy supported by each particle takes relatively large values persistently for long times if the particle is close to an entanglement. Thus, if the interaction is averaged over appropriate time intervals, we can detect active spots on the chai

E. Orignac, Y. Suzumura, T. Giamarchi

The effect of interchain hopping and interaction on Anderson localization has been investigated for two coupled chains of spinless fermions with nearest neighbor interaction. Using the renormalization group method, we find that interchain hopping plays a significant role when the correlation gap induced by the interplay of interchain hopping and intrachain i

E. K. O. Hellen, T. P. Simula, M. J. Alava

We study the dynamic scaling properties of an aggregation model in which particles obey both diffusive and driven ballistic dynamics. The diffusion constant and the velocity of a cluster of size $s$ follow $D(s) \sim s^γ$ and $v(s) \sim s^δ$, respectively. We determine the dynamic exponent and the phase diagram for the asymptotic aggregation behavior in one

G. Sambandamurthy, K. DasGupta, V. H. S. Moorthy, N. Chandrasekhar

In this communication we report studies of d.c current-voltage (I-V) characteristics of ultra thin films of Bi, quench condensed on single crystal sapphire substrates at T = 15K. The hysteretic I-V characteristics are explained using a resistively and capacitively shunted junction (RCSJ) model of Josephson junction arrays. The Josephson coupling energy($E_J$

A. S. Rinat, M. F. Taragin

We present a new, semi-phenomenologocal method to extract the condensate fraction n_0(T) from two sets of measured responses of ^4He with identical kinematis at T<T_c and T>T_c.

Avner Peleg, Massimo Conti, Baruch Meerson

Globally conserved interface-controlled coarsening of fractal clusters exhibits dynamic scale invariance and normal scaling. This is demonstrated by a numerical solution of the Ginzburg-Landau equation with a global conservation law. The sharp-interface limit of this equation is volume preserving motion by mean curvature. The scaled form of the correlation f

Mamoru Usami, Sei-ichiro Suga

The dynamical structure factor of the S=1/2 bond-alternating spin chain with a next-nearest-neighbor interaction in magnetic field is investigated using the continued fraction method based on the Lanczos algorithm. When the plateau exists on the magnetization curve, the longitudinal dynamical structure factor shows a large intensity with a periodic dispersio

O. Friedt, M. Braden, G. Andre, P. Adelmann

The phase diagram of Ca$_{2-x}$Sr$_x$RuO$_4$ has been studied by neutron diffraction on powder and single-crystalline samples. The experiments reveal antiferromagnetic order and structural distortions characterized by tilts and rotations of the RuO$_6$-octahedra. There is strong evidence that the structural details of the isovalent samples tune the magnetic

Wilson M. Liu, Brian Chaboyer

We determine the relative ages of the open cluster NGC 188 and selected Hipparcos field stars by isochrone fitting, and compare them to the age of the thick disk globular cluster 47 Tuc. The best fit age for NGC 188 was determined to be $6.5 \pm 1.0$ Gyr. The solar metallicity Hipparcos field stars yielded a slightly older thin disk age, $7.5 \pm 0.7$ Gyr. T

Christopher D. Matzner

Magnetic stresses collimate protostellar winds into a common distribution of force with angle. Sweeping into the ambient medium, such winds drive bipolar molecular outflows whose properties are insensitive to the distribution of ambient gas and to the details of how the wind is launched, and how its intensity varies over time. Moreover, these properties are

Rafael A. Araya-Gochez, Alice K. Harding

We assess the impact of radiation anisotropy on the line shapes that result from relativistic magnetic Compton scattering in the low-density/high-field regime. A Monte Carlo implementation of radiation transport allows for spatial diffusion of photons in arbitrary geometries and accounts for relativistic angular redistribution. The cross section includes nat

David R. Alves, Howard E. Bond, Mario Livio

We have obtained observations of the planetary nebula K648 in the Galactic globular cluster M15 with the Hubble Space Telescope&#39;s WFPC2 camera, covering an interval of 7 days. The frames provide both time-sampled broad-band photometry of the central star and high-resolution images of the nebula in the light of H-alpha, [OIII], and [NII]. In the deep narr

G. García-Segura, J. A. López

This work presents three dimensional, magneto-hydrodynamical simulations of the formation and early evolution of a subgroup of planetary nebulae that exhibit a variety of point-symmetric structures. For bipolar nebulae, the formation of point-symmetric nebular shapes along the inner borders of their opposing lobes and/or collimated outflows or jets internal

A. E. Sansom, J. E. Hibbard, Francois Schweizer, .

We investigate trends of the cold and hot gas content of early-type galaxies with the presence of optical morphological peculiarities, as measured by the fine-structure index (Sigma). HI mapping observations from the literature are used to track the cold-gas content, and archival ROSAT PSPC data are used to quantify the hot-gas content. We find that E and S0

Michael Truss, James Murray, Graham Wynn, Richard Edgar

We present a numerical scheme for the evolution of an accretion disc through a dwarf nova outburst. We introduce a time-varying artificial viscosity into an existing smoothed particle hydrodynamics code optimised for two and three-dimensional simulations of accretion discs. The technique gives rise to coherent outbursts and can easily be adapted to include a