June 1994 arXiv papers — page 9

N. J. Cornish, J. W. Moffat

A non-singular, static spherically symmetric solution to the nonsymmetric gravitational and electromagnetic theory field equations is derived, which depends on the four parameters m, l^2, Q and s, where m is the mass, Q is the electric charge, l^2 is the NGT charge of a body and s is a dimensionless constant. The electromagnetic field invariants are also sin

S. Carlip, R. Cosgrove

In (2+1)-dimensional general relativity, the path integral for a manifold $M$ can be expressed in terms of a topological invariant, the Ray-Singer torsion of a flat bundle over $M$. For some manifolds, this makes an explicit computation of transition amplitudes possible. In this paper, we evaluate the amplitude for a simple topology-changing process. We show

Gary Kleppe

We solve for the retarded Greens function for linearized gravity in a background with a negative cosmological constant, anti de Sitter space. In this background, it is possible for a signal to reach spatial infinity in a finite time. Therefore the form of the Greens function depends on a choice of boundary condition at spatial infinity. We take as our condit

M. Yu. Konstantinov

The causality properties of space-time models with traversable wormholes are considered. It is shown that relativity principle cannot be applied to the motion of the wormhole's mouths in the outer space and the dynamical wormhole transformation into the time machine is impossible. The examples of both causal and noncausal space-time models with traversab

C. Quitmann, P. Almeras, Jian Ma, R. J. Kelley

Doping Bi2Sr2Ca1Cu2O8+y with Co causes a superconductor-insulator transition. We study correlations between changes in the electrical resistivity RHOab(T) and the electronic bandstructure using identical single crystalline samples. For undoped samples the resistivity is linear in temperature and has a vanishing residual resistivity. In angle resolved photoem

R. Rajaraman, S. L. Sondhi

We calculate the lowest Landau level (LLL) current by working in the full Hilbert space of a two dimensional electron system in a magnetic field and keeping all the non-vanishing terms in the high field limit. The answer a) is not represented by a simple LLL operator and b) differs from the current operator, recently derived by Martinez and Stone in a field

Morten Holm Pedersen, Toni Schneider

Using the Monte Carlo technique we study the dependence of transition temperature, penetration depth and specific heat singularity on the pair concentration in the Bose Hubbard model. We observe remarkable agreement with the corresponding properties of cuprates. This points uniquely to Bose condensation of hard-core pairs on a lattice as the mechanism that d

J. J. Rodríguez-Núñez, S. Schafroth, R. Micnas, T. Schneider

We explore the occurrence of pairing effects above $T_{\rm c}$ in the 2D attractive Hubbard model. The presence of pairs above $T_{\rm c}$ goes beyond the BCS approximation, in which pair formation and condensation occur at the same temperature. Using the fully self-conserving $T$-matrix formalism, which is valid above $T_{\rm c}$, we find that (1) the distr

Patrick Juola

With the advent of faster computers, the notion of doing machine translation from a huge stored database of translation examples is no longer unreasonable. This paper describes an attempt to merge the Example-Based Machine Translation (EBMT) approach with psycholinguistic principles. A new formalism for context- free grammars, called *marker-normal form*, is

Lance A. Ramshaw, Mitchell P. Marcus

Eric Brill has recently proposed a simple and powerful corpus-based language modeling approach that can be applied to various tasks including part-of-speech tagging and building phrase structure trees. The method learns a series of symbolic transformational rules, which can then be applied in sequence to a test corpus to produce predictions. The learning pro

Karl Fisher, Ofer Lahav, Yehuda Hoffman, Donald Lynden-Bell

We present a new method for recovering the cosmological density, velocity, and potential fields from all-sky redshift catalogues. The method is based on an expansion of the fields in orthogonal radial (Bessel) and angular (spherical harmonic) functions. In this coordinate system, peculiar velocities introduce a coupling of the radial harmonics describing the

A. P. Bakulev, S. V. Mikhailov

We calculate the contribution from nonlocal vacuum condensates of quark fields to the hadronic part of the photon structure function $F_2(x)$ in the operator product expansion approach to QCD. The result is a smooth function of $x$ and its magnitude is comparable with one of gluon condensate. Extrapolation to the case of real photon is realized with the help

Laszlo E. Szabo

A b s t r a c t It will be argued that 1) the Bell inequalities are not equivalent with those inequalities derived by Pitowsky and others that indicate the Kolmogorovity of a probability model, 2) the original Bell inequalities are irrelevant to both the question of whether or not quantum mechanics is a Kolmogorovian theory as well as the problem of determin

Mihai Horoi, B. Alex Brown, Vladimir Zelevinsky

A method of truncating the large shell model basis is outlined. It relies on the order given by the unperturbed energies of the basis states and on the constancy of their spreading widths. Both quantities can be calculated by a simple averaging procedure. The method is tested in the sd shell where the JT dimensions are of the order of a few thousand. It prov

F. N. Loreti, A. B. Balantekin

We develop the Redfield equation for delta-correlated gaussian noise and apply it to the case of two neutrino flavor or spin precession in the presence of a noisy matter density or magnetic field, respectively. The criteria under which physical fluctuations can be well approximated by the delta-correlated gaussian noise for the above cases are examined. Curr

G. Di Cecio, G. Paffuti

We find the explicit operatorial form of renormalon-type singularities in abelian gauge theory. Local operators of dimension six take care of the first U.V. renormalon, non local operators are needed for I.R. singularities. In the effective lagrangian constructed with these operators non local imaginary parts appearing in the usual perturbative expansion at

S. Krivonos, A. Sorin

We show that the Zamolodchikov's and Polyakov-Bershadsky nonlinear algebras $W_3$ and $W_3^{(2)}$ can be embedded as subalgebras into some {\em linear} algebras with finite set of currents. Using these linear algebras we find new field realizations of $W_3^{(2)}$ and $W_3$ which could be a starting point for constructing new versions of $W$-string theori

R. Akhoury, I. Z. Rothstein

In this letter we investigate the proper normalization for the B meson eikonal valence wave function used in exclusive B decays. The normalization appropriate for a hard scattering process renormalized at the scale $μ$ is determined by calculating the short distance contribution to the purely leptonic decay.

T. Barnes

This report summarizes the experimental and theoretical status of hadronic molecules, which are weakly-bound states of two or more hadrons. We begin with a brief history of the subject and discuss a few good candidates, and then abstract some signatures for molecules which may be of interest in the classification of possible molecule states. Next we argue th

M. A. van Eijck, R. Kobes, Ch. G. van Weert

We consider transformations of the $2\times2$ propagator matrix in real-time finite-temperature field theory, resulting in transformed $n$--point functions. As special cases of such a transformation we examine the Keldysh basis, the retarded/advanced $RA$ basis, and a Feynman-like $F\bar F$ basis, which differ in this context as to how ``economically'&#3

C. A. Dominguez, M. Loewe

We address some criticisms by Eletsky and Ioffe on the extension of QCD sum rules to finite temperature. We argue that this extension is possible, provided the Operator Product Expansion and QCD-hadron duality remain valid at non-zero temperature. We discuss evidence in support of this from QCD, and from the exactly solvable two- dimensional sigma model O(N)

T. Gehrmann, W. J. Stirling

In the past year, polarized deep inelastic scattering experiments at CERN and SLAC have obtained structure function measurements off proton, neutron and deuteron targets at a level of precision never before achieved. The measurements can be used to test the Bjorken and Ellis-Jaffe sum rules, and also to obtain information on the parton distributions in polar

G. Colangelo, M. Knecht, J. Stern

We evaluate theoretical uncertainties to the method of Pais and Treiman to measure the $ππ$ phase shifts in $K_{e4}$ decays. We find that they are very small, below $1\%$.

M. Baig H. Fort, J. B. Kogut

The role of monopoles in quenched compact QED has been studied by measuring the cluster susceptibility and the order parameter $n_{max}/n_{tot}$ previously introduced by Hands and Wensley in the study of the percolation transition observed in non-compact QED. A correlation between these parameters and the energy (action) at the phase transition has been obse

M. Baig, H. Fort

We have simulated the pure gauge compact QED with fixed boundary conditions, on lattices from $6^4$ to $16^4$. We argue that a lattice with this fixed boundary imposition corresponds actually to a lattice with spherical topology. We have found the presence of a phase transition without any trace of discontinuity. Moreover, the specific heat and the Binder cu

Colin J. Morningstar

The heavy-quark mass and wave function renormalizations, energy shift, and radiative corrections to two important couplings, the so-called kinetic couplings, in nonrelativistic lattice QCD are determined to leading order in tadpole-improved perturbation theory. The scales at which to evaluate the running QCD coupling for these quantities, except the wave fun

B. Pietrzyk

The lepton and quark asymmetries measured at LEP are presented. The results of the Standard Model fits to the electoweak data presented at this conference are given. The top mass obtained from the fit to the LEP data is $172^{+13+18}_{-14-20}$ GeV; it is $177^{+11+18}_{-11-19}$ when also the collider, $ν$ and $A_{LR}$ data are included.

Laurens Gunnarsen, Hisa-aki Shinkai, Kei-ichi Maeda

We present a new method for finding principal null directions (PNDs). Because our method assumes as input the intrinsic metric and extrinsic curvature of a spacelike hypersurface, it should be particularly useful to numerical relativists. We illustrate our method by finding the PNDs of the Kastor-Traschen spacetimes, which contain arbitrarily many $Q=M$ blac

O. Venalainen, T. Ala-Nissila, K. Kaski

We have studied the dynamics of spreading of viscous non-volatile fluids on surfaces by MC simulations of SOS models. We have concentrated on the complete wetting regime, with surface diffusion barriers neglected for simplicity. First, we have performed simulations for the standard SOS model. Formation of a single precursor layer, and a density profile with

R. S. Eccleston, T. Barnes, J. Brody, J. W. Johnson

We present results from an inelastic neutron scattering experiment on the candidate Heisenberg spin ladder vanadyl pyrophosphate, (VO)2P2O7. We find evidence for a spin-wave excitation gap of $E_{gap} = 3.7\pm 0.2$ meV, at a band minimum near $Q=0.8 A^{-1}$. This is consistent with expectations for triplet spin waves in (VO)2P2O7 in the spin-ladder model, an

J. M. P. Carmelo, A. H. Castro Neto, D. K. Campbell

We examine and explain the Luttinger-liquid character of models solvable by the Bethe ansatz by introducing a suitable bosonic operator algebra. In the case of the Hubbard chain, this involves two bosonic algebras which apply to {\it all} values of $U$, electronic density, and magnetization. Only at zero magnetization does this lead to the usual charge - spi

N. Schultka, E. Manousakis

We have studied the superfluid density $ρ_{s}$ on various size-lattices in the geometry $L \times L \times H$ by numerical simulation of the $x-y$ model using the Cluster Monte Carlo method. Applying the Kosterlitz-Thouless-Nelson renormalization group equations for the superfluid density we have been able to extrapolate to the $L \to \infty$ limit for a giv

M. Mezard, R. Monasson

The high temperature phase of the three dimensional random field Ising model is studied using replica symmetry breaking framework. It is found that, above the ferromagnetic transition temperature T_f, there appears a glassy phase at intermediate temperatures T_f<T<T_b while the usual paramagnetic phase exists for T>T_b only. Correlation length at T_b is comp

S. V. Kravchenko, Whitney Mason, J. E. Furneaux, J. M. Caulfield

We report the observation of TEMPERATURE-INDUCED transitions between insulator, metal, and quantum-Hall behaviors for transport coefficients in the very dilute high mobility two-dimensional electron system in silicon. We consider the $ν=1$ quantum Hall effect at the border of it&#39;s existence, at very low electron density. Our data show that as the tempera

Deniz Ertas, Mehran Kardar

We study the depinning of a flux line by analytical and numerical methods applied to a phenomenological equation of motion. Transverse fluctuations do not influence the critical behavior of the longitudinal component, justifying ``planar approximations&#34;. In an isotropic medium, longitudinal fluctuations have a roughness exponent $ζ_\parallel=1$, and rela

Henrik Bruus, A. D. Stone

We perform a detailed numerical study of energy-level and wavefunction statistics of a deformable quantum billiard focusing on properties relevant to semiconductor quantum dots. We consider the family of Robnik billiards generated by simple conformal maps of the unit disk; the shape of this family of billiards may be varied continuously at fixed area by tuni

Jürg Fröhlich, Urban M. Studer, Emmanuel Thiran

We briefly review a theoretical picture of the quantum Hall effect in which gauge symmetry of non-relativistic quantum mechanics, the representation theory of U(1)-current algebra, and the study of odd, positive integral quadratic forms on N-dimensional integral lattices play fundamental roles. We present a classification of so-called minimal incompressible

S. H. Park, Y. H. Jeong

The Young&#39;s modulus and the internal friction of amorphous Fe$_{90}$Zr$_{10}$ alloy were measured near the Curie temperature using the vibrating reed technique. The modulus shows softening around $T_c\approx 227K$ and the internal friction undergoes drastic increase at $T_c$. It is found that both the Young&#39;s modulus and the reciprocal of internal fr

Eric Brill

Most recent research in trainable part of speech taggers has explored stochastic tagging. While these taggers obtain high accuracy, linguistic information is captured indirectly, typically in tens of thousands of lexical and contextual probabilities. In [Brill92], a trainable rule-based tagger was described that obtained performance comparable to that of sto

Owen Rambow

This paper defines multiset-valued linear index grammar and unordered vector grammar with dominance links. The former models certain uses of multiset-valued feature structures in unification-based formalisms, while the latter is motivated by word order variation and by ``quasi-trees&#39;&#39;, a generalization of trees. The two formalisms are weakly equivale

Zelal Gungordu, Kemal Oflazer

This paper describes our work on parsing Turkish using the lexical-functional grammar formalism. This work represents the first significant effort for parsing Turkish. Our implementation is based on Tomita&#39;s parser developed at Carnegie-Mellon University Center for Machine Translation. The grammar covers a substantial subset of Turkish including simple a

Dekai Wu

We describe our experience with automatic alignment of sentences in parallel English-Chinese texts. Our report concerns three related topics: (1) progress on the HKUST English-Chinese Parallel Bilingual Corpus; (2) experiments addressing the applicability of Gale & Church&#39;s length-based statistical method to the task of alignment involving a non-Indo-Eur

A. Crisanti, U. Marini Bettolo Marconi

In this paper we present a formulation of the nonlinear stochastic differential equation which allows for systematic approximations. The method is not restricted to the asymptotic, i.e., stationary, regime but can be applied to derive effective equations describing the relaxation of the system from arbitrary initial conditions. The basic idea is to reduce th

F J Summers

The formation of galaxies in hierarchical cosmogonies is studied using high resolution N-body plus SPH hydrodynamics simulations. The collapse of structure is followed self-consistently from Mpc scale filamentary structures to kpc scale galactic objects. The characteristics and formation processes of the galaxy like objects are studied in detail, along with

Ralph A. M. J. Wijers, Bohdan Paczyński

The recent discovery that faint gamma-ray bursts are stretched in time relative to bright ones has been interpreted as support for cosmological distances: faint bursts have their durations redshifted relative to bright ones. It was pointed out, however, that the relative time stretching can also be produced by an intrinsic correlation between duration and lu

Iosif Lapidus, Luciano Nobili, Roberto Turolla

A possible sound origin for the photospheric oscillations in the X--ray bursting sources 1608-522 and 2127+119 is suggested. It is shown that standing sound waves in an expanding spherical envelope can have periods very close to the observed ones. The quite large ratio, $\sim$ 10, of the periods in the two sources is explained in terms of different wave regi

Masashi Chiba, Biman B. Nath

We investigate the effects of the observed UV background radiation on galaxy formation. Photoionization by UV radiation decreases the cooling rate of the gas in halos, so that objects with only large density contrasts can self-shield against the background radiation, thereby allowing the shielded neutral cores to cool and form stars. In the context of the CD

Peter Heeman, James Allen

Interactive spoken dialog provides many new challenges for spoken language systems. One of the most critical is the prevalence of speech repairs. This paper presents an algorithm that detects and corrects speech repairs based on finding the repair pattern. The repair pattern is built by finding word matches and word replacements, and identifying fragments an

S. Narison

This is a short review of the present status of the dynamics of the heavy quarks extracted from QCD spectral sum rules. We discuss the determination of the ``perturbative" quark mass, the decay constants of the $D$ and $B$ mesons, the form factors of the semileptonic and radiative decays of the $B$ mesons, the slope of the Isgur--Wise function and the emerge

A. Angelucci, S. Sorella, D. Poilblanc

We present a novel approach for a systematic large--spin expansion of the $t$-$J$ Hamiltonian which enables us to work without the constraint of no double occupancy. In our scheme we can perform the large--spin limit ensuring that the low energy spin excitations are in {\em exact} correspondence with the physical excitations of the $s={1\over2}$ Hilbert spac

J. S. Dowker

A functorial derivation is presented of a heat-kernel expansion coefficient on a manifold with a singular fixed point set of codimension two. The existence of an extrinsic curvature term is pointed out.

Derek B. Leinweber

Interpolating fields, used to excite hadrons from the QCD vacuum in nonperturbative field-theoretic investigations of hadron properties, are explored with an emphasis on unconventional nucleon interpolators. The QCD continuum model for excited state contributions to QCD correlation functions is a central element in extracting the physics contained in these a

D. J. Navarro, J. Navarro-Salas

It is shown that a static $(1+3)$ anti-de Sitter metric defines, in a natural way, a relativistic harmonic oscillator in Minkowski space. The quantum theory can be solved exactly and leads to wave functions having a significantly different behaviour with respect to the non-relativistic ones. The energy spectrum coincides, up to the ground state energy, with

M. Gourdin, A. M Kamal, Y. Y. Keum, X. Y. Pham

{}From Class I decays : $B^o \ra π^+ ( ρ^+ ) + D^- ( {D^*}^- )$, we determine $a_1$, and from Class III decays : $B^+ \ra π^+ ( ρ^+ ) + \ol{D}^o ( {\ol{D}^*}^o )$, we determine an allowed domain in the $( a_1, a_2 )$ plane. We find that within one standard deviation errors, the allowed band of $a_1$ from Class I decays is at least three standard deviations r

Tomohiro Matsuda

Recently it was shown that discrete R-invariance in superpotential can lead to a successful flat potential in inflation. We suggest that this discrete R-symmetry arises from an underlying supersymmetric gauge theory, which gives rise to a scalar inflaton as a composite field. This discrete R-symmetry is common to the dynamical breaking scenarios in global su

Kevin Cahill

Three techniques for performing gauge-invariant, noncompact lattice simulations of nonabelian gauge theories are discussed. In the first method, the action is not itself gauge invariant, but a kind of lattice gauge invariance is restored by random compact gauge transformations during the successive sweeps of the simulation. This method has been applied to pu

D. J. Summers

We present a simple method of removing the singularities associated with soft photon emission to all orders in perturbation theory through exponentiation, while keeping a consistent description of hard photon emission. We apply this method to the process e+ e- --> mu+ mu- + n photons where we include both Z^0 and photon exchange and retain the muon mass depe

B. Alex Brown, K. Rykaczewski

New calculations are presented for Gamow-Teller beta decay of nuclei near $^{100}$Sn. Essentially all of the $^{100}$Sn Gamow-Teller decay strength is predicted to go to a single state at an excitation energy of 1.8 MeV in $^{100}$In. The first calculations are presented for the decays of neighboring odd-even and odd-odd nuclei which show, in contrast to $^{

Paolo Maraner

A realistic analysis shows that constraining a quantomechanical system produces the effective dynamics to be coupled with {\sl abelian/non-abelian gauge fields} and {\sl quantum potentials} induced by the {\sl intrinsic} and {\sl extrinsic geometrical properties} of the constraint&#39;s surface. This phenomenon is observable in the effective rotational motio

A. Hulsebos, C. P. Korthals-Altes, S. Nicolis

We study abelian gauge theories with anisotropic couplings in $4+D$ dimensions. A layered phase is present, in the absence as well as in the presence of fermions. A line of second order transitions separates the layered from the Coulomb phase, if $D\leq 3$.

Junji Suzuki

We introduce fusion $U_q(G^{(1)}_2)$ vertex models related to fundamental representations. The eigenvalues of their row to row transfer matrices are derived through analytic Bethe ans{ä}tze. By combining these results with our previous studies on functional relations among transfer matrices(the $T$-system), we conjecture explicit eigenvalues for a wide class

T. Schaefer, E. Shuryak, J. Verbaarschot

We explore the idea that the chiral phase transition in QCD can be described as a transition from a disordered instanton liquid to a strongly correlated phase of polarized instanton anti-instanton molecules. We find a number of non perturbative effects caused by the presence of instantons above T_c, among them the fact that instantons contribute to the euqua

Aneesh V. Manohar

The properties of baryons can be computed in a systematic expansion in $1/N_c$, where $N_c$ is the number of colors. Recent results on the axial couplings and masses of baryons (for the case of three flavors) are presented. The results give insight into the structure of flavor $SU(3)$ breaking for baryons. ----------------------------------------------------

Jicai Pan, Charles Gale

We study multiple scatterings of jets on constituents of quark gluon plasma and introduce energy--energy correlations to quantify their effects. The effects from a longitudinally expanding plasma on medium as well as high energy jets are found to be significant at both RHIC and LHC energies. Because jets escape from the plasma long before the completion of m

Kingman Cheung, Robert J. Oakes

Using the recent measurement of the total production rate for $B_s$ and $B_s^*$ mesons in electron-positron annihilation to determine the strange quark mass parameter in the $\bar b\to B_s,\, B_s^*$ fragmentation functions we calculate the momentum distributions of the $B_s$ and $B_s^*$ mesons.

Jose Wudka

In this paper I review several aspects of the use of effective lagrangians in (mainly) electroweak physics. The conditions under which this approach is reliable and useful, as well as the limitations of the formalism are detailed. Various applications are also presented.

A. Denner, S. Dittmaier, G. Weiglein

Application of the background-field method to QCD and the electroweak Standard Model yields gauge-invariant effective actions giving rise to simple Ward identities. Within this method, we calculate the quantities that have been treated in the literature using the pinch technique. Putting the quantum gauge parameter equal to one, we recover the pinch-techniqu

Giancarlo Cella, Giuseppe Curci, Giulia Ricciardi, Andrea Vicere&#39;

In this work we give a detailed description of a method for the calculation of QCD corrections to electroweak processes in dimensional regularization that does not require any definition of the gamma_5 matrix in d dimensions. This method appears particularly convenient in order to limit the algebraic complexity of higher order calculations. As an example, we

Qing Wang, Yu-Ping Kuang, Yu-Ping yi, Tian-Fang Cai

The four-quark condensates appearing in QCD sum rule are calculated nonperturbatively in a realistic QCD motivated extended Nambu-Jona-Lasinio model. The calculation is in the framework of the effective potential for local composite operators up to next-to-the-leading order in the 1/N expansion in which the non-factorized parts of the condensates are include

Elizabeth Jenkins, Aneesh V. Manohar

Relations among the baryon magnetic and transition magnetic moments are derived in the $1/N_c$ expansion. Relations which hold to ALL ORDERS in $SU(3)$ breaking and to leading and first subleading orders in the $1/N_c$ expansion are obtained. Additional relations are found which are valid up to $SU(3)$ breaking at first subleading order in the $1/N_c$ expans

Haret Rosu, Marco Reyes

We discuss the Shannon-Wehrl entropy within the squeezing vocabulary for the cosmological and black hole particle production.

R. Sebastiani

In this paper we describe how to modify GSAT so that it can be applied to non-clausal formulas. The idea is to use a particular ``score&#39;&#39; function which gives the number of clauses of the CNF conversion of a formula which are false under a given truth assignment. Its value is computed in linear time, without constructing the CNF conversion itself. Th

A. Borgida, P. F. Patel-Schneider

This paper analyzes the correctness of the subsumption algorithm used in CLASSIC, a description logic-based knowledge representation system that is being used in practical applications. In order to deal efficiently with individuals in CLASSIC descriptions, the developers have had to use an algorithm that is incomplete with respect to the standard, model-theo

T. Klotz, S. Kobe

All ground states and low-lying excitations of a +/- I Ising spin glass model on a cubic 4 x 4 x 4 lattice with periodical boundary conditions were calculated using a method of combinatorical optimization. The structure of states in the phase space is enlightened by a representation by means of clusters in the configuration space and their connectivity. The

T. Ala-Nissila, O. Venalainen

We present results of numerical simulations to estimate scaling exponents associated with driven surface growth in two spatial dimensions. We have simulated the restricted solid--on--solid growth model and used the time and system size dependent interface width, and the equal time height correlation function to determine the exponents. We also discuss the in

A. Crisanti, H. Rieger

We investigate the zero-temperature quantum phase transition of the random bond Ising chain in a transverse magnetic field. Its critical properties are identical to those of the McCoy-Wu model, which is a classical Ising model in two dimensions with layered disorder. The latter is studied via Monte Carlo simulations and transfer matrix calculations and the c

Stam Nicolis

We study the effect of mixing two rules on the dynamics of one-dimensional cellular automata by large scale numerical simulations. We calculate the decay of the magnetization for the Domany-Kinzel automaton (XOR/AND mixing) to its equilibrium value in the three phases. This requires system sizes in excess of 1 million sites. We also find severe finite size e

Bertrand Duplantier

The statistics of a long closed self-avoiding walk (SAW) or polymer ring on a $ d $-dimensional lattice obeys hyperscaling. The combination $ p_N \left\langle R^2 \right\rangle^{ d/2}_Nμ^{ -N}, $ (where $ p_N $ is the number of configurations of an oriented and rooted $ N $-step ring, $ \left\langle R^2 \right\rangle_ N $ a typical average size squared, and

Michael E. Flatte&#39;

A method of measuring the relative phase of the energy gap in a high-temperature superconductor is suggested for electron energy loss spectroscopy. Energy-resolved measurements of off-specular scattering should show a feature similar to the specular feature associated with the gap. Unlike the specular feature, which reflects an average of the gap over the (n

P. I. Tamborenea, S. Das Sarma

We study within the linear response theory the far-infrared optical absorption spectrum and the collective excitations of an asymmetric, wide parabolic Al$_x$Ga$_{1-x}$As quantum well, consisting of two half-parabolas of different curvatures, in the presence of an in-plane magnetic field. We employ a self-consistent-field approach in the local-density approx

Rebecca Bruce, Janyce Wiebe

Most probabilistic classifiers used for word-sense disambiguation have either been based on only one contextual feature or have used a model that is simply assumed to characterize the interdependencies among multiple contextual features. In this paper, a different approach to formulating a probabilistic model is presented along with a case study of the perfo

R. Michael Young, Johanna D. Moore, Martha E. Pollack

We argue that discourse plans must capture the intended causal and decompositional relations between communicative actions. We present a planning algorithm, DPOCL, that builds plan structures that properly capture these relations, and show how these structures are used to solve the problems that plagued previous discourse planners, and allow a system to part

Roberto Pieraccini, Esther Levin

In this paper we propose a learning paradigm for the problem of understanding spoken language. The basis of the work is in a formalization of the understanding problem as a communication problem. This results in the definition of a stochastic model of the production of speech or text starting from the meaning of a sentence. The resulting understanding algori

Katashi Nagao, Akikazu Takeuchi

Human face-to-face conversation is an ideal model for human-computer dialogue. One of the major features of face-to-face communication is its multiplicity of communication channels that act on multiple modalities. To realize a natural multimodal dialogue, it is necessary to study how humans perceive information and determine the information to which humans a

Nicholas Asher, Alex Lascarides

This paper is about the flow of inference between communicative intentions, discourse structure and the domain during discourse processing. We augment a theory of discourse interpretation with a theory of distinct mental attitudes and reasoning about them, in order to provide an account of how the attitudes interact with reasoning about discourse structure.

Kuang-hua Chen, Hsin-Hsi Chen

To acquire noun phrases from running texts is useful for many applications, such as word grouping,terminology indexing, etc. The reported literatures adopt pure probabilistic approach, or pure rule-based noun phrases grammar to tackle this problem. In this paper, we apply a probabilistic chunker to deciding the implicit boundaries of constituents and utilize

Steinn Sigurdsson, Melvyn B. Davies, Michael Bolte

Recent surveys of the blue straggler (BS) population in the galactic globular cluster M3 (NGC 5272) give the first complete characterization of the number density of BSs as a function of radius over an entire globular cluster. The BSs in M3 are overabundant at large radii, and significantly underabundant at intermediate radii. Here we present the result of a

Steinn Sigurdsson

The $\ddot P$ (Backer 1992, Backer et al. 1993, Thorsett et al. 1993) observed for PSR~B1620-26 in the globular cluster M4 is most likely due to external gravitational jerk from a bound companion. Solving for the $\ddot P$ observed, constrained by the observed $\dot P$, two natural solutions are a jovian mass in a $\gtorder 10 \ AU, e=0.3-0.5$ orbit, or a so

J. G. Skibo, C. D. Dermer, R. Ramaty

We show that gamma ray line emission at $\sim$0.4 MeV and $\lsim 0.2$ MeV can be produced by Compton scattering of beamed radiation in the jets of Galactic black hole candidates. This mechanism has the novel feature of not invoking the presence of $e^+$--$e^-$ pairs. To produce the two lines we employ a symmetric double sided jet with bulk flow velocity of a

Enrique Martinez- Gonzalez, Jose L. Sanz, Joseph Silk

The nonlinear evolution of matter clustering induces temperature anisotropies in the cosmic microwave background. The fluctuations in temperature are produced at a relatively low redshift, $z\simlt 10$, and consequently are not affected by the uncertain reionization proccesses that occurred at earlier epochs. The amplitude of the effect depends on the evolut