July 2004 arXiv papers — page 10

O. V. Man'ko, V. I. Man'ko

Both the set of quantum states and the set of classical states described by symplectic tomographic probability distributions (tomograms) are studied. It is shown that the sets have common part but there exist tomograms of classical states which are not admissible in quantum mechanics and vica versa, there exist tomograms of quantum states which are not admis

Fernando. G. S. L. Brandao, Reinaldo O. Vianna

We express the optimization of entanglement witnesses for arbitrary bipartite states in terms of a class of convex optimization problems known as Robust Semidefinite Programs (RSDP). We propose, using well known properties of RSDP, several new sufficient tests for the separability of mixed states. Our results are then generalized to multipartite density oper

Andrei Khrennikov

The probabilistic structure of quantum mechanics is investigated in the frequency framework. Such an approach can be interpreted as a contextual approach to quantum probabilities. By using rather complicated frequency calculations we reproduce the EPR-Bohm correlation function which is typically derived by using the calculus of probabilities in a Hilbert spa

Carlos Aguirre, Joao Martins, R. Vilela Mendes

A four-node network consisting of a negative loop controlling a positive one is studied. It models some of the features of the p53 gene network. Using piecewise linear dynamics with thresholds, the allowed dynamical classes are fully characterized and coded. The biologically relevant situations are identified and conclusions drawn concerning the effectivenes

V. D. Rusov, A. V. Glushkov, V. N. Vaschenko, V. N. Pavlovich

The energy-balance model of global climate, which is taking into account a nontrivial role of solar and galactic protons, is presented. The model is described by the equation of fold catastrophe relative to increment of temperature, where the variation of a solar insolation and cosmic rays are control parameters. It is shown that the bifurcation equation of

D. A. Glazov, V. M. Shabaev, I. I. Tupitsyn, A. V. Volotka

Calculations of various corrections to the g factor of Li-like ions are presented, which result in a significant improvement of the theoretical accuracy in the region Z = 6-92. The configuration-interaction Dirac-Fock method is employed for the evaluation of the interelectronic-interaction correction of order 1/Z^2 and higher. This correction is combined wit

Roman Schmied, Pierre Carcabal, Adriaan M. Dokter, Vincent P. A. Lonij

We report spectra of various benzene isotopomers and their dimers in helium nanodroplets in the region of the first Herzberg-Teller allowed vibronic transition 610 1B2u<-1A1g (the A00 transition) at ~260 nm. Excitation spectra have been recorded using both beam depletion detection and laser-induced fluorescence. Unlike for many larger aromatic molecules, the

Wei Wang, Jean-Jacques E. Slotine

This letter studies synchronization conditions for distributed dynamic networks with different types of leaders. The role of a leader specifying a desired global state trajectory through local interactions (the power leader) has long been recognized and modeled. This paper introduces the complementary notion of a knowledge leader holding information on the t

Claudio Conti

The generation of finite energy packets of X-waves is analysed in normally dispersive cubic media by using an X-wave expansion. The 3D nonlinear Schroedinger model is reduced to a 1D equation with anomalous dispersion. Pulse splitting and beam replenishment as observed in experiments with water and Kerr media are explained in terms of a higher order breathin

K. D. Sviratcheva, A. I. Georgieva, J. P. Draayer

We explore, within the framework of an algebraic sp(4) shell model, discrete approximations to various derivatives of the energies of the lowest isovector-paired 0^+ states of atomic nuclei in the 40 <A < 100 mass range. The results show that the symplectic model can be used to successfully interpret fine structure effects driven by the proton-neutron (pn) a

L. Mornas

The contribution of Lambda hyperons to neutrino scattering rates is calculated in the random phase approximation in a model where the interaction is described by a Skyrme potential. Finite temperature and neutrino trapping are taken into account in view of applications to the deleptonization stage of protoneutron star cooling. The hyperons can remove the pro

L. Mornas

Available Skyrme parametrizations with hyperons are examined from the point of view of their suitability for applications to neutron stars. It is shown that the hyperons can attenuate or even remove the problem of ferromagnetic instability common to (nearly) all Skyrme parametrizations of the nucleon-nucleon interaction. At high density the results are very

Yutaka Utsuno, Takaharu Otsuka, Thomas Glasmacher, Takahiro Mizusaki

The onset of intruder ground states in Na isotopes is investigated by comparing experimental data and shell-model calculations. This onset is one of the consequences of the disappearance of the N=20 magic structure, and the Na isotopes are shown to play a special role in clarifying the change of this magic structure. Both the electromagnetic moments and the

Cezary Juszczak, Jaroslaw A. Nowak, Jan T. Sobczyk

We have analyzed the consequences of introducing the local density approximation combined with an effective nuclear momentum-dependent potential into the CC quasi-elastic neutrino-nucleus scattering. We note that the distribution of the recoil nucleons momenta becomes smooth for low momentum values and the sharp threshold is removed. Our results may be relev

J. W. Harris, R. Bellwied, N. Smirnov, P. Steinberg

A case is presented for compelling physics at a high luminosity RHIC II collider and a comprehensive new detector system to address this physics. The experimental focus is on detailed jet tomography of the quark gluon plasma (QGP), measuring gluon saturation in the nucleus, investigating the color glass condensate, measuring effects of the QCD vacuum on part

P. Moylan

We make use of a well-know deformation of the Poincaré Lie algebra in $p+q+1$ dimensions ($p+q>0$) to construct the Poincaré Lie algebra out of the Lie algebras of the de Sitter and anti de Sitter groups, the generators of the Poincaré Lie algebra appearing as certain irrational functions of the generators of the de Sitter groups. We have obtained generaliza

Nicolau C. Saldanha

We discuss the homotopy type and the cohomology of spaces of locally convex parametrized curves gamma: [0,1] -> S^2, i.e., curves with positive geodesic curvature. The space of all such curves with gamma(0) = gamma(1) = e_1 and gamma&#39;(0) = gamma&#39;(1) = e_2 is known to have three connected components X_{-1,c}, X_1, X_{-1}. We show several results conce

Delfim F. M. Torres

We obtain a generalization of Noether&#39;s invariance principle for optimal control problems with equality and inequality state-input constraints. The result relates the invariance properties of the problems with the existence of conserved quantities along the constrained Pontryagin extremals. A result of this kind was posed as an open question by Vladimir

A. Eremenko, A. Gabrielov, M. Shapiro, A. Vainshtein

We single out some problems of Schubert calculus of subspaces of codimension 2 that have the property that all their solutions are real provided that the data are real. Our arguments explore the connection between subspaces of codimension 2 and rational functions of one variable.

Arnold W. Miller

A classical theorem of Luzin is that the separation principle holds for the Pi^0_alpha sets but fails for the Sigma^0_alpha sets. We show that for every Sigma^0_alpha set A which is not Pi^0_alpha there exists a Sigma^0_alpha set B which is disjoint from A but cannot be separated from A by a Delta^0_alpha set C. Assuming Pi^1_1-determancy it follows from a t

I. Birindelli, F. Demengel

Through the Maximum principle we define the principal eigenvalue for a class of fully-nonlinear operators that are the non-variational equivalent of the p-Laplacian. We also obtain some a priori Holder estimates for non-negative solutions below that eigenvalue.

Joan S. Birman, William W. Menasco

The purpose of this erratum is to fill a gap in the proof of the `Composite Braid Theorem&#39; in the manuscript &#34;Studying Links Via Closed Braids IV: Composite Links and Split Links (SLVCB-IV)&#34;, Inventiones Math, \{bf 102\} Fasc. 1 (1990), 115-139. The statement of the theorem is unchanged. The gap occurs on page 135, lines $13^-$ to $11^-$, where w

Bruno Chiarellotto, Marianna Fornasiero

In this article, we analyze the connection between the Log De Rham Cohomology of an fs (not necessary log smooth) log scheme $Y$ over $\mathbb C$ (for $Y$ admitting an exact closed immersion into an fs log smooth log scheme over $\mathbb C$), its Log Infinitesimal Cohomology $H^{^.}(Y^{log}_{inf}, \mathcal O_{Y^{log}_{inf}})$, and its Log Betti Cohomology, w

Eric Leichtnam, Paolo Piazza

We discuss the behaviour of the signature index class of closed foliated bundles under the operation of cutting and pasting. Along the way we establish several index theoretic results: we define Atiyah-Patodi-Singer (APS) index classes for Dirac-type operators on foliated bundles with boundary; we prove a relative index theorem for the difference of two APS-

Valerij G. Bardakov

We study the structure of the virtual braid group. It is shown that the virtual braid group is a semi--direct product of the virtual pure braid group and the symmetric group. Also, it is shown that the virtual pure braid group is a semi--direct product of free groups. From these results we obtain a normal form of words in the virtual braid group. We introduc

Izu Vaisman

We express any Courant algebroid bracket by means of a metric connection, and construct a Courant algebroid structure on any orthogonal Whitney sum $E\oplus C$ where E is a given Courant algebroid and C is a flat, pseudo- Euclidean vector bundle. Then, we establish the general expression of the bracket of a transitive Courant algebroid, i.e., a Courant algeb

Maria Evelina Rossi, Ngo Viet Trung, Giuseppe Valla

The notion of regularity has been used by S. Kleiman in the construction of bounded families of ideals or sheaves with given Hilbert polynomial, a crucial point in the construction of Hilbert or Picard scheme. In a related direction, Kleiman proved that if I is an equidimensional reduced ideal in a polynomial ring S over an algebraically closed field, then t

Daniel Beltiţă

We prove that the classical integrability condition for almost complex structures on finite-dimensional smooth manifolds also works in infinite dimensions in the case of almost complex structures that are real analytic on real analytic Banach manifolds. As an application, we extend some known results concerning existence of invariant complex structures on ho

Xiangdong Xie

We show that if a homeomorphism between the ideal boundaries of two Fuchsian buildings preserves the combinatorial cross ratio almost everywhere, then it extends to an isomorphism between the Fuchsian buildings. It follows that Mostow rigidity holds for Fuchsian buildings: if a group acts properly and cocompactly on two Fuchsian buildings X and Y, then X and

Izabella Laba, Malabika Pramanik

We extend Wolff&#39;s &#34;local smoothing&#34; inequality to a wider class of not necessarily conical hypersurfaces of codimension 1. This class includes surfaces with nonvanishing curvature, as well as certain surfaces with more than one flat direction. An immediate consequence is the L^p boundedness of the corresponding Fourier multiplier operators.

F. Morain

Let E be an elliptic curve having complex multiplication by a given quadratic order of an imaginary quadratic field K. The field of definition of E is the ring class field Omega of the order. If the prime p splits completely in Omega, then we can reduce E modulo one the factors of p and get a curve Ep defined over GF(p). The trace of the Frobenius of Ep is k

A. M. Polyakov

This is a review of topics which haunted me for the last 40 years, starting with spontaneous symmetry breaking and ending with gauge/string/space-time correspondence. While the first part of this article is mostly historical, the second contains some comments, opinions and conjectures which are new. This work is prepared for the volume &#34; Fifty Years of t

A. Kirchberg, J. D. Laenge, A. Wipf

We investigate two-dimensional Wess-Zumino models in the continuum and on spatial lattices in detail. We show that a non-antisymmetric lattice derivative not only excludes chiral fermions but in addition introduces supersymmetry breaking lattice artifacts. We study the nonlocal and antisymmetric SLAC derivative which allows for chiral fermions without double

Masaki Yasue

In strongly coupled supersymmetric SO(N_c) gauge theories with N_f-quarks for N_c-2<=N_f(<=3(N_c-2)/2), their low-energy physics can be described by Nambu-Goldstone superfields associated with dynamical flavor symmetry breaking, which should be compared with the absence of flavor symmetry breaking in the conventional description in terms of magnetic degrees

Hitoshi Nishino, Subhash Rajpoot

We present globally supersymmetric models of gauged scale covariance in ten, six, and four-dimensions. This is an application of a recent similar gauging in three-dimensions for a massive self-dual vector multiplet. In ten-dimensions, we couple a single vector multiplet to another vector multiplet, where the latter gauges the scale covariance of the former.

S. Khalil, E. Kou

We analyze the supersymmetric contributions to the B --> Kπprocess. We show that the simultaneous contributions from the penguin diagrams with chargino and gluino in the loop could lead to a possible solution to the B --> K πpuzzle. Our result indicates that including the stringent constraint from the b --> s γbranching ratio, the supersymmeteric models with

V. M. Braun, A. Lenz

We consider constraints on the momentum fraction of the $K$ and $K^*$ meson carried by the strange quark that follow from exact operator identities, similar to those for the divergence of the quark part of the QCD energy-momentum tensor. The existing QCD sum rule estimates are reanalyzed in this context. Our conclusions essentially support the constituent qu

P. Kroll

The handbag mechanism for wide-angle exlusive scattering reactions is discussed and compared with other theoretical approaches. Its application to Compton scattering, meson photoproduction and two-photon annihilations into pairs of hadrons is reviewed.

J. O. Eeg, K. Kumericki, I. Picek

New contributions to the short-distance b --> s eta&#39; transition are considered. They correspond to the quark and gluon content of eta&#39;. Although substantially larger than the referent QCD anomaly tail, they still cannot account for the observed eta&#39; enhancement.

Jan T. Sobczyk, Jaroslaw A. Nowak, Krzysztof M. Graczyk

We constructed a new Monte Carlo generator of events for neutrino CC single pion production on free nucleon targets. The code uses dynamical models of the DIS with the PDFs modified according to the recent JLab data and of the Delta excitation. A comparison with experimental data was done in three channels for the total cross sections and for the distributio

E. Nowak

The present-day experimental situation concerning nucleon form factors in the space-like region shows a substantial discrepancy between measurements via the Rosenbluth method and the recoil polarisation technique. More information about nucleon form factors in the time-like region will not only improve poor experimental knowledge there, but it will also shed

Deog Ki Hong, Chaejun Song

We calculate the decay rate of light scalar mesons, using a diquark chiral effective theory, recently proposed to describe exotic hadrons. In the effective theory the light scalar mesons are postulated to be bound states of diquark and anti-diquark. We find our results are in good agreement with experimental data. The axial couplings of diquarks with pions a

H. Perez Rojas, E. Rodriguez Querts

We study vacuum in a strong magnetic field. It shows a nonlinear response, as a ferromagnetic medium. Anisotropic pressures arise, and a negative pressure is exerted in the direction perpendicular to the field. The analogy of this effect with the Casimir effect is analyzed. The vacuum transverse pressure is found to be of the same order of the statistical pr

Yong Zhou

This manuscript has been removed duo to incorrect contents.

Yong Zhou, Cai-Dian Lü

This manuscript has been removed duo to incorrect contents.

F. Csikor, Z. Fodor, S. D. Katz, T. G. Kovacs

The present work is a summary of the status of lattice pentaquark calculations. After a pedagogic introduction to the basics of lattice hadron spectroscopy we give a critical comparison of results presently available in the literature. Special emphasis is put on presenting some of the possible pitfalls of these calculations. In particular we discuss at lengt

Philippe Tourrenc, Marie-Christine Angonin-Willaime, Xavier Ovido

Atomic wave interferometers are tied to a telescope pointing towards a faraway star in a nearly free falling satellite. Such a device is sensitive to the acceleration and the rotation relatively to the local inertial frame and to the tidal gravitational effects too. We calculate the rotation of the telescope due to the aberration and the deflection of the li

Marcus Hutter, Andrej Muchnik

Solomonoff&#39;s central result on induction is that the posterior of a universal semimeasure M converges rapidly and with probability 1 to the true sequence generating posterior mu, if the latter is computable. Hence, M is eligible as a universal sequence predictor in case of unknown mu. Despite some nearby results and proofs in the literature, the stronger

M. Pedicini, F. Quaglia

In this article we present the implementation of an environment supporting Lévy&#39;s \emph{optimal reduction} for the $λ$-calculus \cite{Lev78} on parallel (or distributed) computing systems. In a similar approach to Lamping&#39;s one in \cite{Lamping90}, we base our work on a graph reduction technique known as \emph{directed virtual reduction} \cite{DPR97}

Ryan Barnett, Eugene Demler, Efthimios Kaxiras

We perform a detailed analysis of the band structure, phonon dispersion, and electron-phonon coupling of three types of small-radius carbon nanotubes (CNTs): (5,0), (6,0), and (5,5) with diameters 3.9, 4.7, and 6.8 Årespectively. The large curvature of the (5,0) CNTs makes them metallic with a large density of states at the Fermi energy. The density of state

M. J. Alava, S. N. Dorogovtsev

We introduce evolving networks where new vertices preferentially connect to the more central parts of a network. This makes such networks compact. Finite networks grown under the preferential compactness mechanism have complex architectures, but infinite ones tend towards the opposite, having rapidly decreasing distributions of connections. We present an ana

J. E. Hirsch

Neither BCS theory nor London theory contain any charge asymmetry. However it is an experimental fact that a rotating superconductor always exhibits a magnetic field parallel, never antiparallel, to its angular velocity. This and several other experimental observations point to a special role of charge asymmetry in superconductivity, which is the foundation

J. M. Taylor, G. Giedke, H. Christ, B. Paredes

We describe a technique for quantum information processing based on localized en sembles of nuclear spins. A qubit is identified as the presence or absence of a collective excitation of a mesoscopic ensemble of nuclear spins surrounding a single quantum dot. All single and two-qubit operations can be effected using hyperfine interactions and single-electron

G. Chiappe, J. Fernández-Rossier, E. Louis, E. Anda

We consider the effective coupling of localized spins in a semiconductor quantum dot embedded in a microcavity. The lowest cavity mode and the quantum dot exciton are coupled and close in energy, forming a polariton. The fermions forming the exciton interact with localized spins via exchange. Exact diagonalization of a Hamiltonian in which photons, spins and

E. Zaremba, I. Nagy, P. M. Echenique

We have used density functional theory to study the nonlinear screening properties of a two-dimensional (2D) electron gas. In particular, we consider the screening of an external static point charge of magnitude Z as a function of the distance of the charge from the plane of the gas. The self-consistent screening potentials are then used to determine the 2D

Paulo S. Kuhn, Marcia C. Barbosa

We present a model for describing flexible polyelectrolytes in a good solvent a nd in the presence of monovalent salt . The molecule composed by $N$ monomers is characterized by the end to end distanc e $R_e=b (Z-1)^γ$ and the number of associated counterions $n$. At high tem peratures the polyelectrolyte behaves as a neutral polymer ($γ=0.588$). Dec reasing

I. Yu. Borisenko, V. I. Kuznetsov, V. A. Tulin, D. Esteve

We have found that the thin film aluminum structures shaped into a chain of micron sized islands connected by narrow isthmuses, can modify their electrical and structural properties under microwave radiation. As a result, at the temperature of 4.2 K the film structures turn into a kind of lateral periodic structure N-S-N, where N is for normal islands, S is

E. Sakellari, N. P. Proukakis, C. S. Adams

The stability of a low temperature Bose-Einstein condensate with attractive interactions in one and three dimensional double-well potentials is discussed. In particular, the tunnelling dynamics of a condensate under the influence of a time-dependent potential gradient is investigated. The condensate is shown to collapse at a critical potential gradient which

M. Widom, M. Mihalkovic

Bulk metallic glass forms when liquid metal alloys solidify without crystalization. In the search for Iron-based bulk glass-forming alloys of the metal-metalloid type (Fe-B- and Fe-C-based), crystals based on the structural prototype C6Cr23 often preempt the amorphous phase. Destabilizing this competing crystal structure could enhance glass-formability. We c

S. El Shawish, J. Bonca, C. D. Batista, I. sega

We calculate the electron spin resonance (ESR) spectra of the quasi-two-dimensional dimer spin liquid SrCu2(BO3)2 as a function of magnetic field B. Using the standard Lanczos method, we solve a Shastry-Sutherland Hamiltonian with additional Dzyaloshinsky-Moriya (DM) terms which are crucial to explain different qualitative aspects of the ESR spectra. In part

G. Cao, X. N. Lin, L. Balicas, S. Chikara

We report recent transport and thermodynamic experiments over a wide range of temperatures for the Mott-like system Ca3Ru2O7 at high magnetic fields, B, up to 30 T. This work reveals a rich and highly anisotropic phase diagram, where applying B along the a-, b-, and c-axis leads to vastly different behavior. A fully spin-polarized state via a first order met

S. A. Prosandeev, U. Waghmare, I. Levin, J. Maslar

First principles computations of Raman intensities were performed for perovskite-family compound CaAl$_{1/2}$Nb$_{1/2}$O$_3$ (CAN). This compound features 1:1 (NaCl-type) ordering of Al and Nb superimposed onto the $b^-b^-c+$ octahedral tilting. Raman tensor for CAN was computed using the package for first-principles computations ABINIT (URL \underline {http

Domenico Giuliano, Arturo Tagliacozzo

By properly generalizing Nozie`res&#39; Fermi liquid theory, we construct an Hamiltonian approach to the scattering of conduction electrons off a spin-1/2 impurity in the ovescreneed Kondo regime, as T -> 0. We derive the S-matrix at the interacting fixed point, and the corresponding phase shifts, together with leading energy corrections to the unitary limit

O. C. Martin, M. Mezard, O. Rivoire

The multi-index matching is an NP-hard combinatorial optimization problem; for two indices it reduces to the well understood bipartite matching problem that belongs to the polynomial complexity class. We use the cavity method to solve the thermodynamics of the multi-index system with random costs. The phase diagram is much richer than for the case of the bip

Danuta Makowiec

The cellular automata discrete dynamical system is considered as the two-stage process: the majority rule for the change in the automata state and the rule for the change in topological relations between automata. The influence of changing topology to the cooperative phenomena, namely zero-temperature ferromagnetic phase transition, is observed.

D. M. Jezek, M. Barranco, M. Guilleumas, D. M. Jezek

We study a confined mixture of bosons and fermions in the quantal degeneracy regime with attractive boson-fermion interaction. We discuss the effect that the presence of vortical states and the displacement of the trapping potentials may have on mixtures near collapse, and investigate the phase stability diagram of the K-Rb mixture in the mean field approxim

Mesfin Tsige, Gary S. Grest

Large scale molecular dynamics and grand canonical Monte Carlo simulation techniques are used to study the behavior of the interdiffusion of a solvent into an entangled polymer matrix as the state of the polymer changes from a melt to a glass. The weight gain by the polymer increases with time $t$ as $t^{1/2}$ in agreement with Fickian diffusion for all case

V. Janis, J. Kolorenc

We discuss conditions for the existence of the diffusion pole and its consequences in disordered noninteracting electron systems. Using only nonperturbative and exact arguments we find against expectations that the diffusion pole can exist only in the diffusive (metallic) regime. We demonstrate that the diffusion pole in the Anderson localization phase would

Dave Boers, Christoph Weiss, Martin Holthaus

We point out that the velocity of propagation of sound wavepackets in a Bose-Einstein condensate filling a three-dimensional cubic optical lattice undergoes a maximum with increasing lattice depth. For a realistic choice of parameters, the maximum sound velocity in a lattice condensate can exceed the sound velocity in a homogeneous condensate with the same a

V. Janis, L. Zdeborova

We use real replicas to investigate stability of thermodynamic homogeneity of the free energy of the Sherrington-Kirkpatrick (SK) model of spin glasses. Within the replica trick with the replica symmetric ansatz we show that the averaged free energy at low temperatures is not thermodynamically homogeneous. The demand of minimization of the inhomogeneity of t

H. Sakurai, N. Tsujii, E. Takayama-Muromachi

We have performed specific heat and electric resistivity measurements of Na$_{x}$CoO$_{2}$ ($x=0.70$-0.78). Two anomalies have been observed in the specific heat data for $x=0.78$, corresponding to magnetic transitions at $T_{c}=22$ K and $T_{k}\simeq 9$ K reported previously. In the electrical resistivity, a steep decrease at $T_{c}$ and a bending-like vari

H. Sakurai, S. Takenouchi, N. Tsujii, E. Takayama-Muromachi

Powder Na$_{x}$CoO$_{2}$ ($0.70\leq x\leq 0.84$) samples were synthesized and characterized carefully by X-ray diffraction analysis, inductive-coupled plasma atomic emission spectroscopy, and redox titration. It was proved that $γ$-Na$_{x}$CoO$_{2}$ is formed only in the narrow range of $0.70\leq x\leq 0.78$. Nevertheless, the magnetic properties depend stro

Ol&#39;ga V. Dimitrova

We found the universal relationship between frequency-dependent spin-Hall conductivity and magnetic susceptibility in clean 2D electron systems with Rashba coupling: $σ_{sH}(Ω)= \frac{e}{(gμ_B)^2m_b}χ_\parallel(Ω)$ in the presence of an arbitrary two-particle spin-conserving interaction. We show that the Coulomb interaction renormalizes the spin-Hall constan

J. Krawczyk, T. Prellberg, A. Rechnitzer, A. L. Owczarek

In this paper we present simulations of a surface-adsorbed polymer subject to an elongation force. The polymer is modelled by a self-avoiding walk on a regular lattice. It is confined to a half-space by an adsorbing surface with attractions for every vertex of the walk visiting the surface, and the last vertex is pulled perpendicular to the surface by a forc

Takaki Muramatsu, Shigeki Yonezawa, Yuji Muraoka, Zenji Hiroi

Recently new pyrochlore oxides superconductors AOs2O6 (A=K,Rb,Cs) were found and we measured the pressure dependence of magnetization up to 1.2 GPa in order to deduce the pressure effect of Tc in the three beta-pyrochlore oxides. It is found that the initial pressure dependence of Tc is positive for all the compounds. Only KOs2O6 exhibits a saturation in Tc

K. Conlon, H. Luo, D. Viehland, J. F. Li

Spatially resolved neutron diffraction as a function of crystal depth in Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_{3}$ reveals the presence of a distinct near-surface region. A dramatic change in both the lattice constant and the Bragg peak intensity as a function of crystal depth is observed to occur in this region over a length scale $\sim$ 100 $μ$m. This confirms a pre

A. Bhattacharya, M. Eblen-Zayas, N. E. Staley, A. L. Kobrinskii

The glassy response of thin films of La0.8Ca0.2MnO3 to external magnetic and gated electrostatic fields in a field-effect geometry has been studied at low temperatures. A hierarchical response with irreversible memory effects, non-ergodic time evolution, aging and annealing behavior of the resistance suggest that the dynamics are governed by strain relaxatio

M. Eblen-Zayas, A. Bhattacharya, N. E. Staley, A. L. Kobrinskii

Ultrathin La0.8Ca0.2MnO3 films have been measured in a field-effect geometry. The electric field due to the gate produces a large ambipolar decrease in resistance at low temperatures. This is attributed to the development of a pseudogap in the density of states and the couple of localized charge to strain. The gate effect and mangetoresistance are interprete

J. Bonca, A. Ramsak, T. Rejec

We show that the numerical method [M.E. Torio, K. Hallberg, A.H. Ceccatto, and C.R. Proetto, Phys. Rev. B 65, 085302 (2002), cond-mat/0108167v2] does not reproduce correctly the Kondo physics in quantum dot systems with interaction.

Ivan C. Danchev

We show that the cyclic evolution of an order parameter in a many-body system with spontaneous symmetry breaking in the ground state brings about a dissipative geometric phase. This phase originates from the same mechanism that leads to dissipation in thermo-field dynamics studied earlier by Umezawa and his collaborators and appears to be a manifestation of

Hal Tasaki

We study nonequilibrium steady states of the driven lattice gas with two particles, using the most general stochastic transition rules that satisfy the local detailed balance condition. We observe that i) the universal $1/r^d$ long range correlation may be found already in the two-particle models, but ii) the magnitude (or even the existence/absence) of the

Yuki Kawaguchi, Mikio Nakahara, Tetsuo Ohmi

Topological phase imprinting is a unique technique for vortex formation in a Bose-Einstein condensate (BEC) of alkali metal gas, in that it does not involve rotation: BEC is trapped in a quadrupole field with a uniform bias field which is reversed adiabatically leading to vortex formation at the center of the magnetic trap. The scenario has been experimental

G. H. Tovmassian, R. Napiwotzki, M. G. Richer, G. Stasinska

We report FUSE and new deep optical spectroscopic observations of PN G 135.9+55.9, the most oxygen-poor planetary nebula located in the Galactic halo. These observations allow us to estimate the gravity of the central star by fitting the profile of the observed H I absorption lines with NLTE model atmospheres. Our best fit implies that the central star is st

Remy Indebetouw, Kelsey E. Johnson, Peter Conti

We present a systematic survey for ultracompact HII (UCHII) regions in the Magellanic Clouds. Understanding the physics of massive star formation (MSF) is a critical astrophysical problem. The study of MSF began in our galaxy with surveys of UCHII regions, but before now this has not been done for other galaxies. We selected candidates based on their Infrare

Wenfei Yu, Michiel van der Klis, Rob Fender

We have analyzed {\it Rossi} X-ray timing explorer (RXTE) pointed observations of the outbursts of black hole and neutron star soft X-ray transients in which an initial low/hard state or `island&#39; state, followed by a transition to a softer state, was observed. In three sources, the black hole transient XTE J1550-564, the neutron star transient Aquila X-1

C. G. Bassa, B. W. Stappers

We present optical astrometry of archival ground and space based imaging of the companion to PSR J1740-5340. The optical position of the companion is significantly offset from the timing position of the pulsar. We briefly investigate the effects of this inconsistency on other timing parameters and compare our position with an improved position of PSR J1740-5

Smita Mathur, Dirk Grupe

We show that black holes grow substantially by accretion at close to Eddington rates. Using a complete sample of soft X-ray selected AGNs, Grupe & Mathur (2004) have shown that narrow line Seyfert 1 galaxies, as a class, lie below the M_BH-sigma relation of normal galaxies. Some NLS1s, however, lie on or close to the M_BH-sigma relation. Here we show that no

A. L. Cox, L. S. Sparke

We have used the Very Large Array aperture synthesis telescope to conduct a radio continuum survey of polar-ring galaxies, at 20cm and 6cm. Forty objects were observed at 20cm with 5&#34; resolution. Twenty (50%) of the program sources were detected at 20cm, down to our 5-sigma limit of 0.5 mJy/beam. This detection rate is similar to those in surveys with co

V. I. Zhdanov, P. V. Tytarenko, M. S. Borshch

We present a criterion for a shock wave existence in relativistic magnetic hydrodynamics with an arbitrary (possibly non-convex) equation of state. The criterion has the form of algebraic inequality that involves equation of state of the fluid; it singles out the physical solutions and it can be easily checked for any discontinuity satisfying concervation la

A. M. Mason, C. D. Wilson

We present a 9&#39;x9&#39; fully-sampled map of the CO J=1-0 emission in the nearby starburst galaxy Maffei 2 obtained at the Five College Radio Astronomy Observatory. The map reveals previously known strong CO emission in the central starburst region as well as an extended asymmetric distribution with bright CO lines at the ends of the bar and in a feature

B. F. Williams, L. O. Sjouwerman, A. K. H. Kong, J. D. Gelfand

We compare a deep (37 ks) Chandra ACIS-S image of the M31 bulge to Local Group Survey narrow-band optical data and Very Large Array (VLA) radio data of the same region. Our precisely registered images reveal two new optical shells with X-ray counterparts. These shells have sizes, [S II]/H-alpha flux ratios, and X-ray spectral properties typical of supernova

Y. G. Tsamis, D. Pequignot

We present results from dual-abundance photoionization modelling of the planetary nebula SMC N87 (SMC-SMP 27). The models succesfully resolve the observed discrepancy between the heavy-element abundances derived semiempirically from the optical recombination lines and the collisionally excited lines, incorporating a H-poor gaseous component in the main body

Robert Selkowitz, Eric G. Blackman

We reexamine stochastic Fermi acceleration (STFA) in the low energy (Newtonian) regime in the context of solar flares. The particle energization rate depends a dispersive term and a coherent gain term. The energy dependence of pitch angle scattering is important for determining the electron energy spectrum. For scattering by whistler wave turbulence, STFA pr

M. G. Bernardini, C. L. Bianco, P. Chardonnet, F. Fraschetti

We analyze the data of the Gamma-Ray Burst/Supernova GRB030329/SN2003dh system obtained by HETE-2 (GCN [1]), R-XTE (GCN [2]), XMM (Tiengo et al. [3]) and VLT (Hjorth et al. [4]) within our theory (Ruffini et al. [5] and references therein) for GRB030329. By fitting the only three free parameters of the EMBH theory, we obtain the luminosity in fixed energy ba

I. Prandoni, H. R. de Ruiter, P. Parma

The apparent change in the composition of the parent optical objects of radio sources around 1 mJy (at 1.4 GHz) is now well established, although there is still some debate about the relative importance of classical radio galaxies and star-forming galaxies at sub-mJy levels (see e.g. Gruppioni et al. 1999; Prandoni et al. 2001b). It is clear, however, that a

F. De Paolis, G. Ingrosso, A. A. Nucita

Supermassive black hole binaries (SMBHBs) may exist in the centers of galaxies and active galactic nuclei (AGN) and are expected to be fairly common in the Universe as a consequence of merging processes between galaxies. The existence of SMBHBs can be probed by looking for double nuclei in galaxy centers or, more easily, detecting periodic behavior in the ob

D. S. Wiebe, W. D. Watson

(abridged) The polarized thermal radiation at far infrared and submillimeter wavelengths from dust grains in interstellar clouds with irregular magnetic fields is simulated. We show that the polarization properties of quiescent clouds and of star-forming regions are consistent with Kolmogorov-like turbulent magnetic fields that are comparable in magnitude to

R. Bass, A. Del Popolo

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

Diego F. Torres, Gustavo E. Romero, Felix Mirabel

The jets of microquasars with high-mass stellar companions are exposed to the dense matter field of the stellar wind as well as to the photon densities found in the surrounding medium. Photopion and proton-proton interactions could then lead to copious production of neutrinos. In this work, we analyze the hadronic microquasar model, particularly in what conc

Rubén Vigara

A Dehn sphere in a closed 3-manifold M is a 2-sphere immersed in M with only double curve and triple point singularities. The Dehn sphere S fills M if it defines a cell-decomposition of M. The inverse image in S^{2} of the double curves of S is the Johansson diagram of S and if S fills M it is possible to reconstruct M from the diagram. A Johansson represent