February 2005 arXiv papers — page 6

Thomas A. Gardiner, James M. Stone

In these proceedings we present recent efforts to understand the energetics of magnetohydrodynamic (MHD) turbulence driven by the magneto-rotational instability (MRI). These studies are carried out in the local (shearing box) approximation using the Athena simulation code. Athena is a higher order Godunov algorithm based on the piecewise parabolic method (PP

Jeremy S. Heyl

Rossby waves (or r-modes) on the surface of a neutron star have become a leading model for the oscillations observed during the tail of Type-I X-ray bursts. Their frequency evolution matches well with the observed frequency drifts of the oscillations in the bursts, and the burning appears to excite these waves quite naturally. This paper addresses the detail

Martin Cohen, Duane F. Carbon, William J. Welch, Tanya Lim

We have imaged two normal, non-coronal, infrared-bright K giants, Alpha Tau and Alpha Boo, in the 1.4-mm and 2.8-mm continuum using the Berkeley Illinois Maryland Association millimeter array. These stars have been used as important absolute calibrators for several infrared infrared satellites. Our goals are: (1) to establish whether these stars radiate as s

David Merritt, Julio F. Navarro, Aaron Ludlow, Adrian Jenkins

We explore similarities in the luminosity distribution of early type galaxies and the mass profiles of LCDM halos. The spatial structure of these systems may be accurately described by a simple law where the logarithmic slope of the projected density is a power law of radius; the Sersic law. We show that this law provides a significantly better fit than a th

Nicolas Dauphas

Comparisons between the predicted abundances of short-lived r-nuclides (107Pd, 129I, 182Hf, and 244Pu) in the interstellar medium (ISM) and the observed abundances in the early solar system (ESS) conclusively showed that these nuclides cannot simply be derived from galactic chemical evolution (GCE) if synthesized in a unique stellar environment. It was thus

Asim Mahmood, R. Rajesh

In the ellipsoidal collapse model, the critical density for the collapse of a gravitationally bound object is a function of its mass. In the excursion set formalism, this translates into a moving barrier problem such that the mass function of dark matter haloes is given by the first crossing probability of a random walker across the barrier. In this paper, w

A. R. King, M. E. Beer, D. J. Rolfe, K. Schenker

We consider the population of black widow pulsars (BWPs). The large majority of these are members of globular clusters. For minimum companion masses < 0.1 Msun, adiabatic evolution and consequent mass loss under gravitational radiation appear to provide a coherent explanation of all observable properties. We suggest that the group of BWPs with minimum compan

C. Babusiaux, G. Gilmore, M. Irwin

We present here a detailed study of the Sculptor dSph galaxy red giant branch (RGB) and horizontal branch (HB) morphology, combining new near-infrared photometry from CIRSI, with optical data from the ESO WFI. For a Sculptor-like old and generally metal-poor system, the position of RGB stars on the colour-magnitude diagram is mainly metallicity dependent. Th

L. Di Fabrizio, A. Bragaglia, M. Tosi, G. Marconi

We present deep CCD BVI photometry of the distant, old open cluster Berkeley 22, covering from the red giants branch (RGB) to about 6 magnitudes below the main sequence (MS) turn-off. Using the synthetic Colour - Magnitude Diagram method with three different types of stellar evolutionary tracks, we estimate values and theoretical uncertainty of distance modu

Andreja Gomboc, Andrej Cadez

To complement hydrodynamic studies of the tidal disruption of the star by a massive black hole, we present the study of stellar luminosity and its variations, produced by the strong gravitational field of the black hole during a close encounter. By simulating the relativistically moving star and its emitted light and taking into account general relativistic

A. Gomboc, A. Monfardini, C. Guidorzi, C. G. Mundell

The 2-m robotic Liverpool Telescope (LT) is ideally suited to the rapid follow-up of unpredictable and transient events such as GRBs. Our GRB follow-up strategy is designed to identify optical/IR counterparts in real time; it involves the automatic triggering of initial observations, on receipt of an alert from Gamma Ray Observatories HETE-2, INTEGRAL and Sw

B. Acke, M. E. van den Ancker, C. P. Dullemond

We present high spectral-resolution optical spectra of 49 Herbig Ae/Be stars in a search for the [O I] 6300A line. The vast majority of the stars in our sample show narrow (FWHM < 100 km/s) emission lines, centered on the stellar radial velocity. In only three sources is the feature much broader (~400 km/s), and strongly blueshifted (-200 km/s) compared to t

Maxim Lyutikov

In binary radio pulsar system J0737-3039, slow pulsar B shows orbital modulations of intensity, being especially bright at two short orbital phases. We propose that these modulations are due to distortion of pulsar B magnetosphere by pulsar A wind which produces orbital phase-dependent changes of the direction along which radio waves are emitted. In our mode

Umin Lee, Tod E. Strohmayer

We calculate light curves produced by $r$-modes with small azimuthal wavenumbers, $m$, propagating in the surface fluid ocean of rotating neutron stars. We include relativistic effects due to rapid rotation, and propagate photons from the stellar surface to a distant observer using the Schwarzschild metric. The wave motions of the surface $r$-modes are confi

Mario Rabinowitz

The Black Hole enigma has produced many paradoxes. A consensus regarding the resolution of some conundrums such as the Naked Singularity Paradox and the Black Hole Lost Information Paradox (LIP) has still not been achieved. Black hole complementarity as related to the LIP and the LIP itself are challenged by gravitational tunneling radiation. Where possible,

B. Kyung, S. S. Kancharla, D. Sénéchal, A. -M. S. Tremblay

We study the evolution of a Mott-Hubbard insulator into a correlated metal upon doping in the two-dimensional Hubbard model using the Cellular Dynamical Mean Field Theory. Short-range spin correlations create two additional bands apart from the familiar Hubbard bands in the spectral function. Even a tiny doping into this insulator causes a jump of the Fermi

L. M. Feher, A. Nemethi, R. Rimanyi

We present a formula for the degree of the discriminant of irreducible representations of a Lie group, in terms of the roots of the group and the highest weight of the representation. The proof uses equivariant cohomology techniques, namely, the theory of Thom polynomials, and a new method for their computation. We study the combinatorics of our formulas in

Qingjuan Yu, Youjun Lu, Guinevere Kauffmann

Observations have shown that the Eddington ratios (the ratio of the bolometric luminosity to the Eddington luminosity) in QSOs/active galactic nuclei (AGNs) cover a wide range. In this paper we connect the demography of AGNs obtained by the Sloan Digital Sky Survey with the accretion physics around massive black holes and propose that the diversity in the Ed

Lei Ni

In this paper we prove a new matrix Li-Yau-Hamilton estimate for Kähler-Ricci flow. The form of this new Li-Yau-Hamilton estimate is obtained by the interpolation consideration originated in \cite{Ch1}. This new inequality is shown to be connected with Perelman&#39;s entropy formula through a family of differential equalities. In the rest of the paper, We sh

M. A. Caprio, F. Iachello

The phase diagram of a two-fluid bosonic system is investigated. The proton-neutron interacting boson model (IBM-2) possesses a rich phase structure involving three control parameters and multiple order parameters. The surfaces of quantum phase transition between spherical, axially-symmetric deformed, and SU*(3) triaxial phases are determined, and the evolut

Kaustubh Agashe, Roberto Contino, Raman Sundrum

The evolution of Standard Model gauge couplings is studied in a non-supersymmetric scenario in which the hierarchy problem is resolved by Higgs compositeness above the weak scale. It is argued that massiveness of the top quark combined with precision tests of the bottom quark imply that the right-handed top must also be composite. If, further, the Standard M

Monica Valluri, Laura Ferrarese, David Merritt, Charles L. Joseph

Hubble Space Telescope (HST) images and spectra of the nucleated dwarf elliptical galaxy NGC 205 are combined with 3-integral axisymmetric dynamical models to constrain the mass (M_BH) of a putative nuclear black hole. This is only the second attempt, after M33, to use resolved stellar kinematics to search for a nuclear black hole with mass below 10^6 solar

F. Matteucci, F. Calura

In this paper the role of very massive pop III stars in the chemical enrichment of the early universe is discussed. We first compare our predictions with the abundance ratios measured in the high redshift Lyman-alpha forest to check whether they are compatible with the values predicted by assuming that the early universe was enriched by massive pop III stars

Y. Wiaux, L. Jacques, P. Vandergheynst

Wavelets on the sphere are reintroduced and further developed independently of the original group theoretic formalism, in an equivalent, but more straightforward approach. These developments are motivated by the interest of the scale-space analysis of the cosmic microwave background (CMB) anisotropies on the sky. A new, self-consistent, and practical approac

Hirosi Ooguri, Cumrun Vafa, Erik Verlinde

We argue that the topological string partition function, which has been known to correspond to a wave-function, can be interpreted as an exact ``wave-function of the universe&#39;&#39; in the mini-superspace sector of physical superstring theory. This realizes the idea of Hartle and Hawking in the context of string theory, including all loop quantum correcti

Elias P. Gyftopoulos

On the occasion of the 100th anniversary of the beginning of the revolutionary contributions to physics by Einstein, I am happy to respond to a problem posed by him in 1905. He said: In this paper it will be shown that according to the molecular-kinetic theory of heat, bodies of microscopically-visible size suspended in a liquid will perform movements of suc

Vittorio Giovannetti, Rosario Fazio

A new class of state transformations that are quantum mechanically prohibited is introduced. These can be seen as the generalization of the universal-NOT transformation which, for all pure inputs state of a given Hilbert space produces pure outputs whose projection on the original state is fixed to a value smaller than one. The case of not pure output states

A. M. Grundland, A. Strasburger, W. J. Zakrzewski

We study some geometrical aspects of two dimensional orientable surfaces arrising from the study of CP^N sigma models. To this aim we employ an identification of R^(N(N+2)) with the Lie algebra su(N+1) by means of which we construct a generalized Weierstrass formula for immersion of such surfaces. The structural elements of the surface like its moving frame,

A. M. Read

(abridged) High spatial and spectral resolution Chandra X-ray observations of the anomalous merging galaxy NGC520, a similarly-evolved system to the well-known Antennae galaxies, are presented here. Of great interest is the fact that NGC520, on account of it being due to the result of an encounter between one gas-rich disk and one gas-poor disk, appears in X

Torben Jabben, Norbert Grewe, Frithjof Anders

The ionic Hubbard model on a cubic lattice is investigated using analytical approximations and Wilson&#39;s renormalization group for the charge excitation spectrum. Near the Mott insulating regime, where the Hubbard repulsion starts to dominate all energies, the formation of correlated bands is described. The corresponding partial spectral weights and local

Francisco S. N. Lobo

It has been suggested that a possible candidate for the present accelerated expansion of the Universe is &#39;&#39;phantom energy&#39;&#39;. The latter possesses an equation of state of the form $ω\equiv p/ρ<-1$, consequently violating the null energy condition. As this is the fundamental ingredient to sustain traversable wormholes, this cosmic fluid present

F. Freire, N. D. Antunes, P. Salmi, A. Achucarro

We study the symmetry breaking pattern of an O(4) symmetric model of scalar fields, with both charged and neutral fields, interacting with a photon bath. Nagasawa and Brandenberger argued that in favourable circumstances the vacuum manifold would be reduced from S^3 to S^1. Here it is shown that a selective condensation of the neutral fields, that are not di

Martin Hasenbusch

We study the classical XY (plane rotator) model at the Kosterlitz-Thouless phase transition. We simulate the model using the single cluster algorithm on square lattices of a linear size up to L=2048.We derive the finite size behaviour of the second moment correlation length over the lattice size xi_{2nd}/L at the transition temperature. This new prediction a

Frank C. van den Bosch, Simone M. Weinmann, Xiaohu Yang, H. J. Mo

The brightest galaxy in a dark matter halo is expected to reside at rest at the center of the halo. In this paper we test this `Central Galaxy Paradigm&#39; using group catalogues extracted from the 2dFGRS and the SDSS. For each group we compute a parameter, R, defined as the difference between the velocity of the brightest group galaxy and the average veloc

Dinesh Singh, Nader Mobed, Giorgio Papini

We discuss the propagation of neutrino wave packets in a Lense-Thirring space-time using a gravitational phase approach. We show that the neutrino oscillation length is altered by gravitational corrections and that neutrinos are subject to helicity flip induced by stellar rotation. For the case of a rapidly rotating neutron star, we show that absolute neutri

G. Ramachandran, M. S. Vidya, J. Balasubramanyam

A new approach to identify the independent amplitudes along with their partial wave multipole expansions, for photo and electro-production is suggested,which is generally applicable to mesons with arbitrary spin-parity. These amplitudes facilitate direct identification of different resonance contributions.

C. Albertus, E. Hernández, J. Nieves, J. M. Verde-Velasco

We present results for different observables in weak decays of pseudoscalar and vector mesons with a heavy $c$ or $b$ quark. The calculations are done in a nonrelativistic constituent quark model improved at some instances by heavy quark effective theory constraints. We determine pseudoscalar and vector meson decay constants that within a few per cent satisf

Michael Thies, Konrad Urlichs

Baryons in the large N limit of (1+1)-dimensional Gross-Neveu models with either discrete or continuous chiral symmetry have long been known. We generalize their construction to the case where the symmetry is explicitly broken by a bare mass term in the Lagrangian. In the discrete symmetry case, the exact solution is found for arbitrary bare fermion mass, us

Curtis S. Cooper, Adam P. Showman

We calculate the meteorology of the close-in transiting extrasolar planet HD 209458b using a global, three-dimensional atmospheric circulation model. Dynamics are driven by perpetual irradiation of one hemisphere of this tidally locked planet. The simulation predicts global temperature contrasts of ~500 K at the photosphere and the development of a steady su

Brett McInnes

One of the main virtues of string gas cosmology is that it resolves cosmological singularities. Since the Universe can be approximated by a locally asymptotically de Sitter spacetime by the end of the inflationary era, a singularity theorem implies that these cosmologies effectively violate the Null Energy Condition [not just the Strong Energy Condition]. We

L. Barbieri-Viale

This is an overview and a preview of the theory of &#34;mixed motives of level 1&#34; explaining some results, projects, ideas and indicating a bunch of problems.

Sandro Sorella

An appropriate iterative scheme for the minimization of the energy, based on the variational Monte Carlo (VMC) technique, is introduced and compared with existing stochastic schemes. We test the various methods for the 1D Heisenberg ring and the 2D t-J model and show that, with the present scheme, very accurate and efficient calculations are possible, even f

Olaf Kaczmarek, Felix Zantow

We study the change in free and internal energy due to the presence of a heavy quark anti-quark pair in a thermal heat bath in QCD with 2-flavors of staggered quarks at finite temperature. We discuss string breaking below as well as screening above the transition. Similarities and differences to the quenched case are discussed.

Olaf Kaczmarek, Felix Zantow

We present lattice studies of the running coupling in 2-flavor QCD. The coupling at zero temperature (T=0) is extracted from Wilson loops while the coupling at finite temperature ($T\neq0$) is determined from Polyakov loop correlation functions.

Ginestra Bianconi, Matteo Marsili

Loops are subgraphs responsible for the multiplicity of paths going from one to another generic node in a given network. In this paper we present an analytic approach for the evaluation of the average number of loops in random scale-free networks valid at fixed number of nodes N and for any length L of the loops. We bring evidence that the most frequent loop

A. S. Gupta, A. Pathak

Classical Floyd-Warshall algorithm is used to solve all-pairs shortest path problem on a directed graph. The classical algorithm runs in \mathcal{O} (V^{3}) time where V represents the number of nodes. Here we have modified the algorithm and proposed a quantum algorithm analogous to Floyd-Warshall algorithm which exploits the superposition principle and runs

Moshe Dayan

The Nambu-Gorkov generalized Hartree-Fock theory of superconductivity is further generalized to treat simultaneously two kinds of correlations: the correlations that lead to superconductivity, as well as the correlations that produce the pseudogap in the normal state. The treatment of these simultaneous double correlations is done by enlarging the dimension

Yuri Aisaka, Yoichi Kazama

The pure spinor formalism for the superstring, initiated by N. Berkovits, is derived at the fully quantum level starting from a fundamental reparametrization invariant and super-Poincare invariant worldsheet action. It is a simple extension of the Green-Schwarz action with doubled spinor degrees of freedom with a compensating local supersymmetry on top of th

Hou Hong-Sheng, Ma Wen-Gan, Zhang Ren-You, Jiang Yi

For very large values of $\tanβ$, charged Higgs boson pair production at the Large Hadron Collider (LHC) from the scattering of two bottom quarks can proceed dominantly. We investigated the cross sections of charged Higgs boson pair production via the subprocess $b\bar{b} \to H^+H^-$ at the LHC including the next-to-leading order (NLO) QCD corrections in the

J. -C. Boileau, J. Batuwantudawe, R. Laflamme

We discuss the potential of quantum key distribution (QKD) for long distance communication by proposing a new analysis of the errors caused by dark counts. We give sufficient conditions for a considerable improvement of the key generation rates and the security thresholds of well-known QKD protocols such as Bennett-Brassard 1984, Phoenix-Barnett-Chefles 2000

Tsvi Piran

I review several central open questions concerning GRB Jets. 1) I discuss a new estimates of the beaming correction for the rate of GRBs ~ 75 +- 20. 2) I discuss the universal structured jet (USJ) model and conclude that while jets might be structured they are less likely to be universal. 3) I discuss recent observations of a sideways expansion of a GRB afte

William Gordon Ritter

In the study of d-dimensional quantum channels $(d \geq 2)$, an assumption which is not very restrictive, and which has a natural physical interpretation, is that the corresponding Kraus operators form a representation of a Lie algebra. Physically, this is a symmetry algebra for the interaction Hamiltonian. This paper begins a systematic study of channels de

A. M. Ozorio de Almeida, O. Brodier

The Heisenberg evolution of a given unitary operator corresponds classically to a fixed canonical transformation that is viewed through a moving coordinate system. The operators that form the bases of the Weyl representation and its Fourier transform, the chord representation, are, respectively, unitary reflection and translation operators. Thus, the general

Ugo Boscain, Paolo Mason

On a two-level quantum system driven by an external field, we consider the population transfer problem from the first to the second level, minimizing the time of transfer, with bounded field amplitude. On the Bloch sphere (i.e. after a suitable Hopf projection), this problem can be attacked with techniques of optimal syntheses on 2-D manifolds. Let $(-E,E)$

David J. Fernandez C., Encarnacion Salinas-Hernandez

The confluent second-order supersymmetric quantum mechanics, for which the factorization energies tend to a single value, is studied. We show that the Wronskian formula remains valid if generalized eigenfunctions are taken as seed solutions. The confluent algorithm is used to generate SUSY partners of the Coulomb potential.

Tao Yang, Qiang Zhang, Teng-Yun Chen, Shan Lu

Realistic linear quantum information processing necessitates the ability to synchronously generate entangled photon pairs either at the same or at distant locations. Here, we report the experimental realization of synchronized generation of independent entangled photon pairs. The quality of synchronization is confirmed by observing a violation of Bell&#39;s

K. G. H. Vollbrecht, J. I. Cirac

We show how to perform reversible universal quantum computation on a translationally invariant pure state, using only global operations based on next-neighbor interactions. We do not need not to break the translational symmetry of the state at any time during the computation. Since the proposed scheme fulfills the locality condition of a quantum cellular aut

G. Ivanyos, S. Massar, A. B. Nagy

We study the computation power of lattices composed of two dimensional systems (qubits) on which translationally invariant global two-qubit gates can be performed. We show that if a specific set of 6 global two qubit gates can be performed, and if the initial state of the lattice can be suitably chosen, then a quantum computer can be efficiently simulated

Ingvar Lindgren

The connection between many-body theory (MBPT)--in perturbative and non-perturbative form--and quantum-electrodynamics (QED) is reviewed for systems of two fermions in an external field. The treatment is mainly based upon the recently developed covariant-evolution-operator method for QED calculations [Lindgren et al. Phys. Rep. 389, 161 (2004)], which has a

Feng Pan, Dan Liu, Guoying Lu, J. P. Draayer

A complete analysis of entangled triqubit pure states is carried out based on a new simple entanglement measure. An analysis of all possible extremally entangled pure triqubit states with up to eight terms is shown to reduce, with the help of SLOCC transformations, to three distinct types. The analysis presented are most helpful for finding different entangl

Roger Guimera, Luis A. Nunes Amaral

High-throughput techniques are leading to an explosive growth in the size of biological databases and creating the opportunity to revolutionize our understanding of life and disease. Interpretation of these data remains, however, a major scientific challenge. Here, we propose a methodology that enables us to extract and display information contained in compl

M. Coppey, O. Benichou, R. Voituriez, M. Moreau

It is widely recognized that the cleaving rate of a restriction enzyme on target DNA sequences is several orders of magnitude faster than the maximal one calculated from the diffusion--limited theory. It was therefore commonly assumed that the target site interaction of a restriction enzyme with DNA has to occur via two steps: one--dimensional diffusion alon

Ovidiu Lipan, Wing H. Wong

The structure of a genetic network is uncovered by studying its response to external stimuli (input signals). We present a theory of propagation of an input signal through a linear stochastic genetic network. It is found that there are important advantages in using oscillatory signals over step or impulse signals, and that the system may enter into a pure fl

Martin Howard, Karsten Kruse

We use the oscillating Min proteins of Escherichia coli as a prototype system to illustrate the current state and potential of modeling protein dynamics in space and time. We demonstrate how a theoretical approach has led to striking new insights into the mechanisms of self-organization in bacterial cells and indicate how these ideas may be applicable to mor

Julien Mayor, Wulfram Gerstner

In randomly connected networks of pulse-coupled elements a time-dependent input signal can be buffered over a short time. We studied the signal buffering properties in simulated networks as a function of the networks state, characterized by both the Lyapunov exponent of the microscopic dynamics and the macroscopic activity derived from mean-field theory. If

Julien Mayor, Wulfram Gerstner

We investigate the performance of sparsely-connected networks of integrate-and-fire neurons for ultra-short term information processing. We exploit the fact that the population activity of networks with balanced excitation and inhibition can switch from an oscillatory firing regime to a state of asynchronous irregular firing or quiescence depending on the ra

M. Ravasz, A. Balog, V. Marko, Z. Neda

Studies on distribution, abundance and diversity of species revealed fascinating universalities in macroecology. Many of these patterns, like the species-area and range-abundance relationship or the year-to-year fluctuations in population sizes are expressed as power-law distributions, and indicate thus scale-invariance. The species abundance distribution (S

Albert Fannjiang, Knut Solna

We analyze the time reversal of waves in a turbulent medium using the parabolic Markovian model. We prove that the time reversal resolution can be a nonlinear function of the wavelength and independent of the aperture. We establish a duality relation between the turbulence-induced wave spread and the time-reversal resolution which can be viewed as an uncerta

D. P. Barber, R. Jaganathan, M. Vogt

Snake ``resonances&#39;&#39; are classified in terms of the invariant spin field and the amplitude dependent spin tune. Exactly at snake ``resonance&#39;&#39; there is no continuous invariant spin field at most orbital amplitudes.

G. Gori, F. Ramponi, F. Barranco, P. F. Bortignon

Oscillations of mainly surface character (S=0 modes) give rise, in atomic nuclei, to an attractive (induced) pairing interaction, while spin (S=1) modes of mainly volume character generate a repulsive interaction, the net effect being an attraction which accounts for a sizeable fraction of the experimental pairing gap. Suppressing the particle-vibration coup

F. Barranco, P. F. Bortignon, R. A. Broglia, G. Colo&#39;

The dependence on the single-particle states of the pairing matrix elements of the Gogny force and of the bare low-momentum nucleon-nucleon potential $v_{low-k}$ is studied in the semiclassical approximation for the case of a typical finite, superfluid nucleus ($^{120}$Sn). It is found that the matrix elements of $v_{low-k}$ follow closely those of $v_{Gogny

N. K. Timofeyuk, P. Descouvemont

It has been suggested recently (Phys. Rev. Lett. 91, 232501 (2003)) that charge symmetry of nucleon-nucleon interactions relates the Asymptotic Normalization Coefficients (ANCs) of proton and neutron virtual decays of mirror nuclei. This relation is given by a simple analytical formula which involves proton and neutron separation energies, charges of residua

H. Mueller, V. I. Komarov

Data from KEK on subthreshold $\bar{\mrm{p}}$ as well as on $π^\pm$ and $\mrm{K}^\pm$ production in proton-, deuteron- and $α$-induced reactions at energies between 2.0 and 12.0 A GeV for C, Cu and Pb targets are described within a unified approach. We use a model which considers a nuclear reaction as an incoherent sum over collisions of varying numbers of p

S. D. Covrig, E. J. Beise, R. Carr, K. K. Gustafsson

A cryogenic horizontal single loop target has been designed, built, tested and operated for the G$^0$ experiment in Hall C at Jefferson Lab. The target cell is 20 cm long, the loop volume is 6.5 l and the target operates with the cryogenic pump fully immersed in the fluid. The target has been designed to operate at 30 Hz rotational pump speed with either liq

Zahera Jabeen, Neelima Gupte

We study the phase diagram of the sine circle map lattice with random initial conditions and identify the various types of dynamical behaviour which appear here. We focus on the regions which show spatio-temporal intermittency and characterise the accompanying scaling behaviour. Directed percolation exponents are seen at some points in the parameter space in

M. H. Albert, M. Elder, A. Rechnitzer, P. Westcott

We construct a sequence of finite automata that accept subclasses of the class of 4231-avoiding permutations. We thereby show that the Wilf-Stanley limit for the class of 4231-avoiding permutations is bounded below by 9.35. This bound shows that this class has the largest such limit among all classes of permutations avoiding a single permutation of length 4

Bhupinder Singh Anand

We consider the immediate consequence of an arguable addition to the standard Deduction Theorems of first order theories.

Ulrich Goertz, Thomas J. Haines

We study certain nearby cycles sheaves on an affine flag manifold which arise naturally in the Beilinson-Gaitsgory deformation of the affine flag manifold to the affine Grassmannian. We study the multiplicity functions we introduced in an earlier paper, which encode the data of the Jordan-Hoelder series. We prove the multiplicity functions are polynomials in

A. J. Duncan, I. V. Kazatchkov, V. N. Remeslennikov

In this paper we establish results that will be required for the study of the algebraic geometry of partially-commutative groups. We define classes of groups axiomatised by sentences determined by a graph. Among the classes which arise this way we find CSA and CT groups. We study the centraliser dimension of a group, with particular attention to the height o

Giulia Furioli, Camillo Melzi, Alessandro Veneruso

We prove dispersive and Strichartz inequalities for the solution of the wave equation related to the full Laplacian on the Heisenberg group, by means of Besov spaces defined by a Littlewood--Paley decomposition related to the spectral resolution of the full Laplacian. This requires a careful analysis due also to the non-homogeneous nature of the full Laplaci

Inna Bumagin, Olga Kharlampovich, Alexei Miasnikov

We prove that the isomorphism problem for finitely generated fully residually free groups is decidable. We also show that each finitely generated fully residually free group G has a decomposition that is invariant under automorphisms of G, and obtain a structure theorem for the group of outer automorphisms Out(G).

Mihai Ciucu

In 1963 Fisher and Stephenson \cite{FS} conjectured that the monomer-monomer correlation on the square lattice is rotationally invariant. In this paper we prove a closely related statement on the hexagonal lattice. Namely, we consider correlations of two quadromers (four-vertex subgraphs consisting of a monomer and its three neighbors) and show that they are

Barry Simon

We prove that the Szegő function, $D(z)$, of a measure on the unit circle is entire meromorphic if and only if the Verblunsky coefficients have an asymptotic expansion in exponentials. We relate the positions of the poles of $D(z)^{-1}$ to the exponential rates in the asymptotic expansion. Basically, either set is contained in the sets generated from the oth

David Damanik, Barry Simon

We present necessary and sufficient conditions on the Jost function for the corresponding Jacobi parameters $a_n -1$ and $b_n$ to have a given degree of exponential decay.

David Damanik, Barry Simon

We provide necessary and sufficient conditions for a Jacobi matrix to produce orthogonal polynomials with Szegő asymptotics off the real axis. A key idea is to prove the equivalence of Szegő asymptotics and of Jost asymptotics for the Jost solution. We also prove $L^2$ convergence of Szegő asymptotics on the spectrum.

Barry Simon

We present an expository introduction to orthogonal polynomials on the unit circle.

Nate Harvey, Alexander E. Holroyd, Yuval Peres, Dan Romik

In 1977, Keane and Smorodinsky showed that there exists a finitary homomorphism from any finite-alphabet Bernoulli process to any other finite-alphabet Bernoulli process of strictly lower entropy. In 1996, Serafin proved the existence of a finitary homomorphism with finite expected coding length. In this paper, we construct such a homomorphism in which the c

Ugo Boscain, Yacine Chitour

Consider the control system given by $\dot x=x(f+ug)$, where $x\in SO(3)$, $|u|\leq 1$ and $f,g\in so(3)$ define two perpendicular left-invariant vector fields normalized so that $\|f\|=\cos(\al)$ and $\|g\|=\sin(\al)$, $\al\in ]0,π/4[$. In this paper, we provide an upper bound and a lower bound for $N(α)$, the maximum number of switchings for time-optimal t

Juan Carlos Álvarez Paiva, Carlos E. Durán

We study the geometry of an important class of generic curves in the Grassmannian manifolds of $n$-dimensional subspaces and Lagrangian subspaces of $R^{2n}$ under the action of the linear and linear symplectic group.

Kozhan Roman

In this paper the notion of $\infty$-open-multicommutativity of functors in the category of compact Hausdorff spaces is considered. This property is a generalization of the open-multicommutativity on the case of infinite diagrams. It is proved that every open-multicommutative functor is $\infty$-open-multicommutative.

H. A. Dye

A realization of a virtual link diagram is obtained by choosing over/under markings for each virtual crossing. Any realization can also be obtained from some representation of the virtual link. (A representation of a virtual link is a link diagram on an oriented 2-dimensional surface.) We prove that if a minimal genus representation meets certain criteria th

Allan J. MacLeod

We consider the problem of finding integer-sided triangles with R/r an integer, where R and r are the radii of the circumcircle and incircle respectively. We show that such triangles are relatively rare.

Roman Kozhan

We consider the correspondence assigning to every Radon measure on two Tychonoff coordinate spaces the set of probability measures with these marginals. It is proved that this correspondence is continuous.

Jonathan Barker, Victor Snaith

In the 2-local stable homotopy category the group of left-bu-module automorphisms of bu\wedge bo which induce the identity on mod 2 homology is isomorphic to the group of infinite upper triangular matrices with entries in the 2-adic integers. We identify the conjugacy class of the matrix corresponding to 1\wedgeψ^3, where ψ^3 is the Adams operation.

Victorita Dolean, Frédéric Nataf, Gerd Rapin

We propose new domain decomposition methods for systems of partial differential equations in two and three dimensions. The algorithms are derived with the help of the Smith factorization of the operator. This could also be validated by numerical experiments.

Guillaume Ricotta

In this paper, some asymptotic formulas are proved for the harmonic mollified second moment of a family of Rankin-Selberg L-functions. One of the main new input is a substantial improvement of the admissible length of the mollifier which is done by solving a shifted convolution problem by a spectral method on average. A first consequence is a new subconvexit

Haibao Duan, Chao Liang

Every 1-connected topological 4-manifold M admits a $S^{1}$-covering by $#_{r-1}S^{2}\times S^{3}$, where $r=$rank$H^{2}(M;\QTR{Bbb}{Z})$.

Ivan Marin

In this very short note we show that the residual nilpotence of pure Artin groups of spherical type is easily deduced from the faithfulness of the Krammer-Digne representations.

Mihai Ciucu

In the last decade there have been many results about special families of graphs whose number of perfect matchings is given by perfect or near perfect powers. In this paper we present an approach that allows proving them in a unified way. We use this approach to prove a conjecture of James Propp stating that the number of tilings of the so-called Aztec dunge

Franc Forstneric

Suppose that Y is a complex manifold with the property that any holomorphic map from a compact convex set in a complex Euclidean space C^n (for any n) to Y is a uniform limit of entire maps from C^n to Y. We prove that a holomorphic map from a closed complex subvariety X_0 in a Stein manifold X to the manifold Y extends to a holomorphic map of X to Y provide