June 2007 arXiv papers — page 31

G. Cecil, J. A. Rose

We review knowledge of galaxy structures obtained by their emitted light and in the local universe where they can be studied in great detail. We discuss the shapes of, and stellar motions within, galaxies, compositional clues derived from their spectra, and what luminous matter implies about their dark matter content. Implications on the current theory of hi

Andrei Mikhailov, Sakura Schafer-Nameki

Quantum non-local charges are central to the quantum integrability of a sigma-model. In this paper we study the quantum consistency and UV finiteness of non-local charges of string theory in AdS(5)xS(5). We use the pure spinor formalism. We develop the near-flat space expansion of the transfer matrix and calculate the one-loop divergences. We find that the l

Mark Hannam, Sascha Husa, Jose A. Gonzalez, Ulrich Sperhake

We analyze numerical-relativity (NR) waveforms that cover nine orbits (18 gravitational-wave cycles) before merger of an equal-mass system with low eccentricity, with numerical uncertainties of 0.25 radians in the phase and less than 2% in the amplitude; such accuracy allows a direct comparison with post-Newtonian (PN) waveforms. We focus on one of the PN ap

Chiara Cammarota, Andrea Cavagna

We introduce a novel method for calculating the size of the critical nucleus and the value of the surface tension in systems with first order phase transition. The method is based on classical nucleation theory, and it consists in studying the thermodynamics of a sphere of given radius embedded in a frozen metastable surrounding. The frozen configuration cre

Evert Rol, Alexander van der Horst, Klaas Wiersema, Sandeep K. Patel

GRB051022 was undetected to deep limits in early optical observations, but precise astrometry from radio and X-ray showed that it most likely originated in a galaxy at z~0.8. We report radio, optical, near infra-red and X-ray observations of GRB051022. Using the available X-ray and radio data, we model the afterglow and calculate the energetics of the afterg

Kai P. Schmidt, J. Dorier, Andreas Laeuchli, Frederic Mila

We show that correlated hopping of triplets, which is often the dominant source of kinetic energy in dimer-based frustrated quantum magnets, produces a remarkably strong tendency to form supersolid phases in a magnetic field. These phases are characterized by simultaneous modulation and ordering of the longitudinal and transverse magnetization respectively.

Anastasia Doikou, Davide Fioravanti, Francesco Ravanini

The generalized (1+1)-D non-linear Schrodinger (NLS) theory with particular integrable boundary conditions is considered. More precisely, two distinct types of boundary conditions, known as soliton preserving (SP) and soliton non-preserving (SNP), are implemented into the classical $gl_N$ NLS model. Based on this choice of boundaries the relevant conserved q

Cecilia B. M. H. Chirenti, Luciano Rezzolla

Gravastars have been recently proposed as potential alternatives to explain the astrophysical phenomenology traditionally associated to black holes, raising the question of whether the two objects can be distinguished at all. Leaving aside the debate about the processes that would lead to the formation of a gravastar and the astronomical evidence in their su

Jeremy Avigad, Philipp Gerhardy, Henry Towsner

The mean ergodic theorem is equivalent to the assertion that for every function K and every epsilon, there is an n with the property that the ergodic averages A_m f are stable to within epsilon on the interval [n,K(n)]. We show that even though it is not generally possible to compute a bound on the rate of convergence of a sequence of ergodic averages, one c

Sergio Caracciolo, Alan D. Sokal, Andrea Sportiello

Given a hypergraph G, we introduce a Grassmann algebra over the vertex set, and show that a class of Grassmann integrals permits an expansion in terms of spanning hyperforests. Special cases provide the generating functions for rooted and unrooted spanning (hyper)forests and spanning (hyper)trees. All these results are generalizations of Kirchhoff's matr

Jeffrey T. Buboltz, Charles Bwalya, Krystle Williams, Matthew Schutzer

For some time now, we have been using a FRET-based strategy to make high-resolution studies of phase behavior in ternary lipid-raft membrane mixtures. Our FRET experiments can be carried out on ordinary, polydisperse multilamellar vesicle suspensions, so we are able to prepare our samples according to a procedure that was designed specifically to guard again

MAGIC Collaboration, J. Albert

We report on the results from the observations in very high energy band (VHE, E_gamma > 100 GeV) of the black hole X-ray binary (BHXB) Cygnus X-1. The observations were performed with the MAGIC telescope, for a total of 40 hours during 26 nights, spanning the period between June and November 2006. Searches for steady gamma-ray signals yielded no positive res

Graeme Mitchison, Richard Jozsa, Sandu Popescu

The notion of weak measurement provides a formalism for extracting information from a quantum system in the limit of vanishing disturbance to its state. Here we extend this formalism to the measurement of sequences of observables. When these observables do not commute, we may obtain information about joint properties of a quantum system that would be forbidd

M. Bache, J. Moses, F. W. Wise

We present a detailed study of soliton compression of ultra-short pulses based on phase-mismatched second-harmonic generation (\textit{i.e.}, the cascaded quadratic nonlinearity) in bulk quadratic nonlinear media. The single-cycle propagation equations in the temporal domain including higher-order nonlinear terms are presented. The balance between the quadra

John P Robinson, Henning Schomerus

We investigate the conductance of normal-conductor/graphene/normal-conductor (NGN) junctions for arbitrary on-site potentials in the normal and graphitic parts of the system. We find that a ballistic NGN junction can display insulating behavior even when the charge-carrier density in the graphene part is finite. This effect originates in the different k inte

Violetta Bernyk, Robert C. Dalang, Goran Peskir

Let $X=(X_t)_{t\ge0}$ be a stable Lévy process of index $α\in(1,2)$ with no negative jumps and let $S_t=\sup_{0\le s\le t}X_s$ denote its running supremum for $t>0$. We show that the density function $f_t$ of $S_t$ can be characterized as the unique solution to a weakly singular Volterra integral equation of the first kind or, equivalently, as the unique sol

S. Lo, A. V. Korol, A. V. Solov'yov

This is an investigation on the dynamical screening of an atom confined within a fullerene of finite width. The two surfaces of the fullerene lead to the presence of two surface plasmon eigenmodes. It is shown that, in the vicinity of these two eigenfrequencies, there is a large enhancement of the confined atom's photoabsorption rate.

Xuehan Cheng, Wu Jing

We prove that every multiplicative bijective map, Jordan bijective map, and Jordan triple bijective map from a triangular algebra onto any ring is automatically additive.

Xuehan Cheng, Wu Jing

In this note we prove that elementary maps on triangular algebras are automically additive.

M. Feito, F. J. Cao

Closed-loop or feedback control ratchets use information about the state of the system to operate with the aim of maximizing the performance of the system. In this paper we investigate the effects of a time delay in the feedback for a protocol that performs an instantaneous maximization of the center-of-mass velocity. For the one and the few particle cases t

A. E. Ruiz-Velasco, H. Swan, E. Troja, D. Malesani

We report on follow-up observations of the GRB 060927 using the ROTSE-IIIa telescope and a suite of larger aperture ground-based telescopes. An optical afterglow was detected 20 s after the burst, the earliest rest-frame detection of optical emission from any GRB. Spectroscopy performed with the VLT about 13 hours after the trigger shows a continuum break at

R. Cote, M. -A. Lemonde, C. B. Doiron, A. M. Ettouhami

In a quantizing magnetic field, the two-dimensional electron (2DEG) gas has a rich phase diagram with broken translational symmetry phases such as Wigner, bubble, and stripe crystals. In this paper, we derive a method to get the dynamical matrix of these crystals from a calculation of the density response function performed in the Generalized Random Phase Ap

D. S. Novikov

Electron properties of graphene are described in terms of Dirac fermions. Here we thoroughly outline the elastic scattering theory for the two-dimensional massive Dirac fermions in the presence of an axially symmetric potential. While the massless limit is relevant for pristine graphene, keeping finite mass allows for generalizations onto situations with bro

Mariano A. Ruiz, Demetrio Stojanoff

We study the relationship between operators, orthonormal basis of subspaces and frames of subspaces (also called fusion frames) for a separable Hilbert space $\mathcal{H}$. We get sufficient conditions on an orthonormal basis of subspaces $\mathcal{E} = \{E_i \}_{i\in I}$ of a Hilbert space $\mathcal{K}$ and a surjective $T\in L(\mathcal{K}, \mathcal{H})$ in

Dorin Ervin Dutkay, Palle E. T. Jorgensen, Gabriel Picioroaga

For points in $d$ real dimensions, we introduce a geometry for general digit sets. We introduce a positional number system where the basis for our representation is a fixed $d$ by $d$ matrix over $\bz$. Our starting point is a given pair $(A, \mathcal D)$ with the matrix $A$ assumed expansive, and $\mathcal D$ a chosen complete digit set, i.e., in bijective

T. J. Oliveira, F. D. A. Aarao Reis

We study numerically finite-size corrections in scaling relations for roughness distributions of various interface growth models. The most common relation, which considers the average roughness $<w_2>$ as scaling factor, is not obeyed in the steady states of a group of ballistic-like models in 2+1 dimensions, even when very large system sizes are considered.

Temitope Gbolahan Jaiyeola

A new condition called ${\cal T}$ condition is introduced for the first time and used to study a pair of isotopic loops. Under this condition, a loop in the pair is a WIPL if and only if the other loop is a WIPL. Furthermore, such WIPLs are isomorphic. The translation elements $f$ and $g$ of a CIPL with the ${\cal T}$ condition(such that its $f,g$-isotope is

Temitope Gbolahan Jaiyeola

Every quasigroup $(S,\cdot)$ belongs to a set of 6 quasigroups, called parastrophes denoted by $(S,π_i)$, $i\in \{1,2,3,4,5,6\}$. It is shown that isotopy-isomorphy is a necessary and sufficient condition for any two distinct quasigroups $(S,π_i)$ and $(S,π_j)$, $i,j\in \{1,2,3,4,5,6\}$ to be parastrophic invariant relative to the associative law. In additio

Luigi Del Debbio, Haralambos Panagopoulos, Ettore Vicari

We review recent results on the theta dependence of the ground-state energy and spectrum of four-dimensional SU(N) gauge theories, where theta is the coefficient of the CP-violating topological term F-Fdual in the Lagrangian. In particular, we discuss the results obtained by Monte Carlo simulations of the lattice formulation of QCD, which allow the investiga

Temitope Gbolahan Jaiyeola

LC-loops, RC-loops and C-loops are collectively called central loops. It is shown that an LC(RC)-loop is a left(right) universal loop. But an LC(RC)-loop is a universal loop if and only if it is a right(left) universal loop. It is observed that not all RC-loops or LC-loops or C-loops are universal loops. But if an RC-loop(LC-loop, C-loop) is universal, then

Artur Sergyeyev, Maciej Blaszak

We present a multiparameter generalization of the Stäckel transform (the latter is also known as the coupling-constant metamorphosis) and show that under certain conditions this generalized Stäckel transform preserves the Liouville integrability, noncommutative integrability and superintegrability. The corresponding transformation for the equations of motion

Raquel Caseiro, Joana M. Nunes da Costa

Jacobi-Nijenhuis algebroids are defined as a natural generalization of Poisson-Nijenhuis algebroids, in the case where there exists a Nijenhuis operator on a Jacobi algebroid which is compatible with it. We study modular classes of Jacobi and Jacobi-Nijenhuis algebroids.

Hui Li

Let $M$ be a connected compact quantizable Kähler manifold equipped with a Hamiltonian action of a connected compact Lie group $G$. Let $M//G=ϕ^{-1}(0)/G=M_0$ be the symplectic quotient at value 0 of the moment map $ϕ$. The space $M_0$ may in general not be smooth. It is known that, as vector spaces, there is a natural isomorphism between the quantum Hilbert

S. Bellucci, S. Krivonos, V. Ohanyan

Proceeding from the superfield action for $N=4, d=1$ nonlinear supermultiplet, equipped with the most general potential term, we find the action describing a charged particle on the sphere $S^3$ in the field of $n$ fixed Dirac dyons. We construct the supercharges and Hamiltonian and analyze some particulary interesting potentials corresponding to the N=4 sup

Srubabati Goswami, Werner Rodejohann

The MiniBooNE and LSND experiments are compatible with each other when two sterile neutrinos are added to the three active ones. In this case there are eight possible mass orderings. In two of them both sterile neutrinos are heavier than the three active ones. In the next two scenarios both sterile neutrinos are lighter than the three active ones. The remain

Christos A. Athanasiadis, Myrto Kallipoliti

The absolute order is a natural partial order on a Coxeter group W. It can be viewed as an analogue of the weak order on W in which the role of the generating set of simple reflections in W is played by the set of all reflections in W. By use of a notion of constructibility for partially ordered sets, it is proved that the absolute order on the symmetric gro

C. Schill

New results on single spin asymmetries of identified charged pion and kaon pairs produced in deep-inelastic scattering of muons on a transversely polarized 6LiD target are presented. The data were taken in the years 2003 and 2004 with the COMPASS spectrometer at CERN with a 160 GeV muon beam from the CERN SPS accelerator. The asymmetries can be interpreted i

Guillaume Beuf, Robi Peschanski, Sebastian Sapeta

``Geometric scaling&#39;&#39;, i.e. the dependence of DIS cross-sections on the ratio Q/Q_S, where Q_S(Y) is the rapidity-dependent \saturation scale, can be theoretically obtained from universal ``traveling wave&#39;&#39; solutions of the nonlinear Balitsky-Kovchegov (BK) QCD evolution equation at fixed coupling. We examine the similar mean-field prediction

Albert Benveniste, Benoit Caillaud, Roberto Passerone

We present the mathematical foundations of the contract-based model developed in the framework of the SPEEDS project. SPEEDS aims at developing methods and tools to support &#34;speculative design&#34;, a design methodology in which distributed designers develop different aspects of the overall system, in a concurrent but controlled way. Our generic mathemat

Sylvain Landron, Marie-Bernadette Lepetit

We studied the influence of the trigonal distortion of the regular octahedron along the (111) direction, found in the $\rm CoO_2$ layers. Under such a distortion the $t_{2g}$ orbitals split into one $a_{1g}$ and two degenerated $e_g^\prime$ orbitals. We focused on the relative order of these orbitals. Using quantum chemical calculations of embedded clusters

B. Pozsgay, G. Takacs

We describe the volume dependence of matrix elements of local fields to all orders in inverse powers of the volume (i.e. only neglecting contributions that decay exponentially with volume). Using the scaling Lee-Yang model and the Ising model in a magnetic field as testing ground, we compare them to matrix elements extracted in finite volume using truncated

Zongzhu Lin, Jie Xiao, Guanglian Zhang

An integral PBW-basis of type $A_1^{(1)}$ has been constructed by Zhang [Z] and Chen [C] using the Auslander-Reiten quiver of the Kronecker quiver. We associate a geometric order to elements in this basis following an idea of Lusztig [L1] in the case of finite type. This leads to an algebraic realization of a bar-invariant basis of $\uq2$. For any affine sym

P. Bozhilov

We find membrane configurations in AdS_4 x S^7, which correspond to the continuous limit of the SU(2) integrable spin chain, considered as a limit of the SU(3) spin chain, arising in N=4 SYM in four dimensions, dual to strings in AdS_5 x S^5. We also discuss the relationship with the Neumann-Rosochatius integrable system at the level of Lagrangians, comparin

F. Sheidaei, M. Bahmanabadi, M. Khakian Ghomi, S. M. Mahdavi

A new technique has been devised for the analysis of extensive air shower data in observing the effect of the moon on this data. In this technique the number of EAS events with arrival directions falling in error circles centered about the moving moon is compared to the mean number of events falling in error circles with centers randomly chosen in the sky. F

Mark R. Dennis, Nikolay I. Zheludev, F. Javier Garcia de Abajo

The plasmon analog of the self-imaging Talbot effect is described and theoretically analyzed. Rich plasmon carpets containing hot spots are shown to be produced by a row of periodically-spaced surface features. A row of holes drilled in a metal film and illuminated from the back side is discussed as a realizable implementation of this concept. Self-images of

Beniamino Cappelletti Montano, Antonio De Nicola, Giulia Dileo

In the present paper we carry on a systematic study of 3-quasi-Sasakian manifolds. In particular we prove that the three Reeb vector fields generate an involutive distribution determining a canonical totally geodesic and Riemannian foliation. Locally, the leaves of this foliation turn out to be Lie groups: either the orthogonal group or an abelian one. We sh

S. Kim, E. Rosolowsky, Y. Lee, Y. Kim

A 21 cm neutral hydrogen interferometric survey of the Large Magellanic Cloud (LMC) combined with the Parkes multi-beam HI single-dish survey clearly shows that the HI gas is distributed in the form of clumps or clouds. The HI clouds and clumps have been identified using a thresholding method with three separate brightness temperature thresholds ($T_b$). Eac

Segismundo S. Izquierdo, Luis R. Izquierdo

This paper, which commented on Newman and Leicht&#39;s &#34;Mixture models and exploratory analysis in networks&#34; (2007, PNAS 104, 9564-9569), has been withdrawn. The reason for this removal is that we misinterpreted the conceptual framework that the authors of the original paper use. Specifically, it is assumed in our paper that the variable theta_ri den

George Lazarides

Inflationary models with a superheavy scale F-term hybrid inflation followed by an intermediate scale modular inflation are considered. The restrictions on the power spectrum P_R of curvature perturbation and the spectral index n_s from the recent data within the power-law cosmological model with cold dark matter and a cosmological constant can be met provid

J. S. Bhattacharyya, Gautam Bhattacharya

Redefining the vacuum state of a free twofold N=1 covariant supersymmetric string action as the one with all the world sheet fermionic excited states occupied, makes the theory anomaly free in D=4 with Minkowski signature. The theory thus describes a critical string in 3+1 dimensions as opposed to earlier N=2 supersymmetric theories describing a 2+2 dimensio

Stephen Clark

Q-balls arise in particle theories with U(1) global symmetry. The coupling of the corresponding scalar field to fermions leads to Q-ball evaporation. In this paper we consider the oposite problem, the case where a Q-ball absorbs particles to grow. In particular we shall use the exact quantum mechanical description of fermions interacting with a Q-ball to sol

M. R. Ahmady, F. Mahmoudi

The branching ratio for the rare two-body B_s -> rho gamma decay is calculated using the factorization assumption. This transition is dominated by the annihilation diagrams and, in principle, prone to receiving substantial contributions from new physics. We estimate Br(B_s -> rho gamma) = 1.6 x 10^-9 within the Standard Model and investigate the sensitivity

Sanjeev Kumar, Arno P. Kampf

We analyze the effects of both bond- and potential-disorder in the vicinity of a first-order metal insulator transition in a two-band model for manganites using a real-space Monte Carlo method. Our results reveal a novel charge-ordered state coexisting with spin-glass behavior. We provide the basis for understanding the phase diagrams of half-doped manganite

Serban Belinschi, Florent Benaych-Georges, Alice Guionnet

The free convolution is the binary operation on the set of probability measures on the real line which allows to deduce, from the individual spectral distributions, the spectral distribution of a sum of independent unitarily invariant square random matrices or of a sum of free operators in a non commutative probability space. In the same way, the rectangular

Paul Busch, Teiko Heinosaari

Joint measurements of qubit observables have recently been studied in conjunction with quantum information processing tasks such as cloning. Considerations of such joint measurements have until now been restricted to a certain class of observables that can be characterized by a form of covariance. Here we investigate conditions for the joint measurability of

Azhar Iqbal, Taksu Cheon

In evolutionary game theory an Evolutionarily Stable Strategy (ESS) is a refinement of the Nash equilibrium concept that is sometimes also recognized as evolutionary stability. It is a game-theoretic model, well known to mathematical biologists, that was found quite useful in the understanding of evolutionary dynamics of a population. This chapter presents a

Jounghun Lee, Pirin Erdogdu

We report a direct observational evidence for the existence of the galaxy spin alignments with the real space tidal field. We calculate the real space tidal field from the real space density field reconstructed recently from the Two Mass Redshift Survey (2MRS) by Erdogdu et al. in 2006. Using a total of 12122 nearby spiral galaxies from the Tully Galaxy Cata

Arpad Hegedus

In an earlier work [1] J. Suzuki proposed a set of nonlinear integral equations (NLIE) to describe the excited state spectrum of the integrable spin-1 XXZ chain in its repulsive regime. In this paper we extend his equations for the attractive regime of the model, and calculate analytically the conformal spectrum of the spin chain. We also discuss the typical

Ming Yu, Xin Zhang

A supersymmetric Hamiltonian is constructed for the edge excitations of the Moore-Read (Pfaffian) like state, which is a realization of the N=2 supersymmetric CS model. Fermionic generators and their conjugates are introduced to deal with the fermion pairing, whose condensation form a BCS like state. After Bogoliubov transformation, a N=2 supersymmetric and

Jonathan M. Borwein, Bruno Salvy

We provide a proof of a conjecture in (Bailey, Borwein, Borwein, Crandall 2007) on the existence and form of linear recursions for moments of powers of the Bessel function $K_0$.

Istvan Gyöngy, Annie Millet

Stochastic evolution equations in Banach spaces with unbounded nonlinear drift and diffusion operators driven by a finite dimensional Brownian motion are considered. Under some regularity condition assumed for the solution, the rate of convergence of various numerical approximations are estimated under strong monotonicity and Lipschitz conditions. The abstra

S. M. Badalyan, G. Vignale, C. S. Kim

We study the spin Coulomb drag in a quasi-two-dimensional electron gas beyond the random phase approximation (RPA). We find that the finite transverse width of the electron gas causes a significant reduction of the spin Coulomb drag. This reduction, however, is largely compensated by the enhancement coming from the inclusion of many-body local field effects

Matthias R. Brust, Steffen Rothkugel

In the field of tutoring systems, investigations have shown that there are many tutoring systems specific to a specific domain that, because of their static architecture, cannot be adapted to other domains. As consequence, often neither methods nor knowledge can be reused. In addition, the knowledge engineer must have programming skills in order to enhance a

C. S. Lim, Nobuhito Maru

We investigate a 5D SU(6) grand gauge-Higgs unification model compactified on an orbifold S^1/Z_2. Ordinary quarks and leptons, together with right-handed neutrinos, are just accommodated into a minimal set of representations of the gauge group, without introducing any exotic states. The proton decay turns out to be forbidden at least at the tree level. We a

Hiroshi Suzuki

We carry out preliminary numerical study of Sugino&#39;s lattice formulation \cite{Sugino:2004qd,Sugino:2004qdf} of the two-dimensional $\mathcal{N}=(2,2)$ super Yang-Mills theory (2d $\mathcal{N}=(2,2)$ SYM) with the gauge group $\SU(2)$. The effect of dynamical fermions is included by re-weighting a quenched ensemble by the pfaffian factor. It appears that

Yves Colombe, Tilo Steinmetz, Guilhem Dubois, Felix Linke

An optical cavity enhances the interaction between atoms and light, and the rate of coherent atom-photon coupling can be made larger than all decoherence rates of the system. For single atoms, this strong coupling regime of cavity quantum electrodynamics (cQED) has been the subject of spectacular experimental advances, and great efforts have been made to con

Yunkyu Bang

Recent neutron scattering experiments have revealed that the generic form of the magnetic excitations in the high-Tc cuprates of wide range of doping has the so-called &#34;hourglass&#34; shape; it features both upward and downward excitations at the incommensurate (IC) momenta spanning from the resonance peak at the commensurate momentum $(π,π)$. We propose

Bei Zeng, Andrew Cross, Isaac L. Chuang

Certain quantum codes allow logic operations to be performed on the encoded data, such that a multitude of errors introduced by faulty gates can be corrected. An important class of such operations are {\em transversal}, acting bitwise between corresponding qubits in each code block, thus allowing error propagation to be carefully limited. If any quantum oper

Elizabeth Baldwin, David Swinarski

We construct the moduli spaces of stable maps, \bar M_g,n(P^r,d), via geometric invariant theory (GIT). This construction is only valid over Spec C, but a special case is a GIT presentation of the moduli space of stable curves of genus g with n marked points, \bar M_g,n; this is valid over Spec Z. Our method follows that used in the case n=0 by Gieseker to c

Francisco Cutanda-Henriquez, Silvia Vargas-Castrillon

Dose volume histograms are a useful tool in state-of-the-art radiotherapy planning, and it is essential to be aware of their limitations. Dose distributions computed by treatment planning systems are affected by several sources of uncertainty such as algorithm limitations, measurement uncertainty in the data used to model the beam and residual differences be

Cyrille Marquet

Following the Good-and-Walker picture, hard diffraction in the high-energy/small-x limit of QCD can be described in terms of eigenstates of the scattering matrix off a Color Glass Condensate. From the CGC non-linear evolution equations, it is then possible to derive the behavior of diffractive cross-sections at small $x.$ I discuss recent results, in particu

Li Yang, Cheol-Hwan Park, Young-Woo Son, Marvin L. Cohen

We present calculations of the quasiparticle energies and band gaps of graphene nanoribbons (GNRs) carried out using a first-principles many-electron Green&#39;s function approach within the GW approximation. Because of the quasi-one-dimension nature of a GNR, electron-electron interaction effects due to the enhanced screened Coulomb interaction and confinem

V. Ramareddy, G. Behinaein, I. Talukdar, P. Ahmadi

We report the observation of high order resonances of the quantum $δ$-kicked accelerator using a BEC kicked by a standing wave of light. The signature of these resonances is the existence of quantum accelerator modes. For the first time quantum accelerator modes were seen near 1/4 and 1/3 of the Talbot time. Using a BEC enabled us to study the detailed struc

Robert Minchin, Jonathan Davies, Michael Disney, Marco Grossi

Many observations indicate that dark matter dominates the extra-galactic Universe, yet no totally dark structure of galactic proportions has ever been convincingly identified. Previously we have suggested that VIRGOHI 21, a 21-cm source we found in the Virgo Cluster using Jodrell Bank, was a possible dark galaxy because of its broad line-width (~200 km/s) un

A. M. Naveira, A. Tarrio

In this paper a method for the resolution of the differential equation of the Jacobi vector fields in the manifold V1 = Sp(2)/SU(2) is exposed. These results are applied to determine areas and volumes of geodesic spheres and balls.

M. Sultan Parvez

Special relativity turns out to be more than coordinate transformations in which the constancy of the speed of light plays the central role between two inertial reference frames. Special relativity, in essence, is a theory of four-dimensional flat spacetime. Euclidian space spans three of the spacetime&#39;s dimensions and time spans the fourth. Properties o

Christoph Gohle, Björn Stein, Albert Schliesser, Thomas Udem

A femtosecond frequency comb provides a vast number of equidistantly spaced narrow band laser modes that can be simultaneously tuned and frequency calibrated with 15 digits accuracy. Our Vernier spectrometer utilizes all of theses modes in a massively parallel manner to rapidly record both absorption and dispersion spectra with a sensitivity that is provided

A. Lesfari

In this paper, we discuss an interaction between complex geometry and integrable systems. Section 1 reviews the classical results on integrable systems. New examples of integrable systems, which have been discovered, are based on the Lax representation of the equations of motion. These systems can be realized as straight line motions on a Jacobi variety of a

Suranjana Ghosh, J. Banerji

We show that the time frequency analysis of the autocorrelation function is, in many ways, a more appropriate tool to resolve fractional revivals of a wave packet than the usual time domain analysis. This advantage is crucial in reconstructing the initial state of the wave packet when its coherent structure is short-lived and decays before it is fully revive

H. R. Dullin, J. D. Meiss

We study the normal forms for incompressible flows and maps in the neighborhood of an equilibrium or fixed point with a triple eigenvalue. We prove that when a divergence free vector field in $\mathbb{R}^3$ has nilpotent linearization with maximal Jordan block then, to arbitrary degree, coordinates can be chosen so that the nonlinear terms occur as a single

Geoffrey Mess

This paper was first written in 1990, but was never published. In it, the author presents a novel approach to the study of constant curvature spacetimes in 2+1 dimensions. A parameterization of flat 2+1-dimensional domains of dependence is given in terms of measured geodesic laminations. There is also an interesting reinterpretation of Thurston&#39;s Earthqu

M. D. Healy

A key step towards the understanding of the origin of ultra-high energy cosmic rays is their mass composition. Primary photons and neutrinos produce markedly different showers from nuclei, while showers of different nuclear species are not easy to distinguish. To maximise the discrimination with the Pierre Auger Observatory ideally all mass-sensitive observa

Zhihui Wang, Le Zhang, Jonathan Sagotsky, Thomas S. Deisboeck

Background The epidermal growth factor receptor (EGFR) is frequently overexpressed in many cancers, including non-small cell lung cancer (NSCLC). In silcio modeling is considered to be an increasingly promising tool to add useful insights into the dynamics of the EGFR signal transduction pathway. However, most of the previous modeling work focused on the mol

Doug Wiedemann, Michael Zieve

We consider n-by-n circulant matrices having entries 0 and 1. Such matrices can be identified with sets of residues mod n, corresponding to the columns in which the top row contains an entry 1. Let A and B be two such matrices, and suppose that the corresponding residue sets S_A and S_B have size at most 3. We prove that the following are equivalent: (1) the

Jaya NN Iyer

In this paper, we investigate Murre&#39;s conjectures on the structure of rational Chow groups and exhibit explicit Chow--Kuenneth projectors for some examples. More precisely, the examples we study are the varieties which have a nef tangent bundle. For surfaces and threefolds which have a nef tangent bundle explicit Chow--Kuenneth projectors are obtained wh

Lucio Mayer, Stelios Kazantzidis, Piero Madau, Monica Colpi

Supermassive black holes (SMBHs) are a ubiquitous component of the nuclei of galaxies. It is normally assumed that, following the merger of two massive galaxies, a SMBH binary will form, shrink due to stellar or gas dynamical processes and ultimately coalesce by emitting a burst of gravitational waves. However, so far it has not been possible to show how two

D. Constantin, Z. S. Siwy

We have investigated ion current rectification properties of a recently prepared bipolar nanofluidic diode. This device is based on a single conically shaped nanopore in a polymer film whose pore walls contain a sharp boundary between positively and negatively charged regions. A semi-quantitative model that employs Poisson and Nernst-Plank equations predicts

F. Raischel, F. Kun, H. J. Herrmann

We present an extension of the continuous damage fiber bundle model to describe the gradual degradation of highly heterogeneous materials under an increasing external load. Breaking of a fiber in the model is preceded by a sequence of partial failure events occurring at random threshold values. In order to capture the subsequent propagation and arrest of cra

François Shindo, James F. Babb, Kate Kirby, Kouichi Yoshino

We have measured the reduced absorption coefficients occurring in the wings of the potassium 4S-5P doublet lines at 404.414 nm and at 404.720 nm broadened by helium gas at pressures of several hundred Torr. At the experimental temperature of 900 K, we have detected a shoulder-like broadening feature on the blue wing of the doublet which is relatively flat be

C. R. Shrader, P. Reig, D. Kazanas

Using archival RXTE data we derive the 2-16 keV Fourier-resolved spectra of the Atoll source 4U 1728-34 in a sequence of its timing states as its low QPO frequency spans the range between 6 and 94 Hz. The increase in the QPO frequency accompanies a spectral transition of the source from its island to its banana states. The banana-states&#39; Fourier-resolved

D. Paneque

The blazar Markarian 501 (Mrk 501) was observed above 100 GeV with the MAGIC Telescope during May, June and July 2005. The high sensitivity of the instrument made possible the detection of the source with high significance in each of the observing nights. During this observational campaign, the emitted gamma-ray flux from Mkn 501 was found to vary by one ord

M. Lopez-Corredoira, J. Betancort-Rijo, J. E. Beckman

The accretion of the intergalactic medium onto the gaseous disc is used to explain the generation of galactic warps. A cup-shaped distortion is expected, due to the transmission of the linear momentum; but, this effect is small for most incident inflow angles and the predominant effect turns out to be the transmission of angular momentum, i.e. a torque givin

A. J. Skinner, B. -L. Hu

We develop a &#34;chain-boson model&#34; master equation, within the Born-Markov approximation, for a few superconducting quantum interference devices (SQUIDs) coupled into a chain and exchanging their angular momenta with a low temperature phonon bath. Our master equation has four generators; we concentrate on the damping and diffusion and use them to study

Jeremy D. Schnittman

Recent numerical simulations of binary black hole mergers show the possibility of producing very large recoil velocities (> 3000 km/s). Kicks of this magnitude should be sufficient to eject the final black hole from virtually any galactic potential. This result has been seen as a potential contradiction with observations of supermassive black holes residing

Marco Brunella

We investigate the accumulation to singular points of leaves of codimension one foliations whose normal bundle is ample, with emphasis on the nonexistence of Levi-flat hypersurfaces.

Alejandro Cabrera

In this paper, we carry a detailed study of mechanical systems with configuration space $Q\longrightarrow Q/G$ for which the base $Q/G$ variables are being controlled. The overall system&#39;s motion is considered to be induced from the base one due to the presence of general non-holonomic constraints. It is shown that the solution can be factorized into dyn

D. Paneque, A. Borgland, A. Bovier, E. Bloom

The Gamma-ray Large Area Space Telescope (GLAST) is an observatory designed to perform gamma-ray astronomy in the energy range 20 MeV to 300 GeV, with supporting measurements for gamma-ray bursts from 10 keV to 25 MeV. GLAST will be launched at the end of 2007, opening a new and important window on a wide variety of high energy astrophysical phenomena . The

Alice K. Harding

Rotation-powered pulsars are excellent laboratories for study of particle acceleration as well as fundamental physics of strong gravity, strong magnetic fields, high densities and relativity. I will review the outstanding questions in pulsar physics and the prospects for finding answers with GLAST LAT observations. LAT observations should significantly incre

José M. Casado, José Gómez-Ordóñez, Manuel Morillo

We analyze the noise induced synchronization between a collective variable characterizing a complex system with a finite number of interacting bistable units and time periodic driving forces. A random phase process associated to the collective stochastic variable is defined. Its average phase frequency and average phase diffusion are used to characterize the

Geir Agnarsson, Agust Egilsson, Magnus Mar Halldorsson

We consider vertex coloring of an acyclic digraph $\Gdag$ in such a way that two vertices which have a common ancestor in $\Gdag$ receive distinct colors. Such colorings arise in a natural way when bounding space for various genetic data for efficient analysis. We discuss the corresponding {\em down-chromatic number} and derive an upper bound as a function o