May 2008 arXiv papers — page 31
Showing 3,001–3,100 of 4,900 papers
Todor Stanev
We examine the anisotropy of the arrival directions of twenty seven ultra high energy cosmic rays detected by the Pierre Auger Collaboration. We confirm the anisotropy of the arrival directions of these events and find a significant correlation with the updated definition of the supergalactic plane at distances up to 70 Mpc, A Monte Carlo calculation of isot
Yoshinori Honma, Satoshi Iso, Yoske Sumitomo, Sen Zhang
Based on the recent proposal of N=8 superconformal gauge theories of the multiple M2 branes, we derive (2+1)-dimensional supersymmetric Janus field theories with a space-time dependent coupling constant. From the original Bagger-Lambert model, we get a supersymmetric field theory with a similar action to the N D2 branes, but the coupling varies with the spac
Ari Pakman, Andrei Parnachev
We study the entanglement entropy in confining theories with gravity duals using the holographic prescription of Ryu and Takayanagi. The entanglement entropy between a region and its complement is proportional to the minimal area of a bulk hypersurface ending on their border. We consider a disk in 2+1 dimensions and a ball in 3+1 dimensions and find in both
A brief survey of the renormalizability of four dimensional gravity for generalized Kodama states
gr-qcEyo Eyo Ita
We continue the line of research from previous works in assessing the suitability of the pure Kodama state both as a ground state for the generalized Kodama states, as well as characteristic of a good semiclassical limit of general relativity. We briefly introduce the quantum theory of fluctuations about DeSitter spacetime, which enables one to examine some
Instanton representation of Plebanski gravity: XIII. Canonical structure of the Petrov classification of nondegenerate spacetimes
gr-qcEyo Ita
The instanton representation of Plebanski gravity admits a natural canonical structure where the (densitized) eigenvalues of the CDJ matrix are the basic momentum space variables. Canonically conjugate configuration variables exist for six distinct configurations in the full theory, referred to as quantizable configurations. The CDJ matrix relates to the Pet
Denys I. Bondar
The Yudin-Ivanov formula [Phys. Rev. A 64, 013409 (2001)] is generalized such that the most general analytical expression for single-electron spectra, which includes the dependence on the instantaneous laser phase, is obtained within the strong field approximation. No assumptions on the momentum of the electron are made. Previously known formulas for single-
John McDonald
We discuss the physical interpretation of unparticles and review the constraints from cosmology. Unparticles may be understood in terms of confined states of a strongly-coupled scale-invariant theory, where scale-invariance implies that the confined states have continuous masses. This picture is consistent with the observation that unparticle operators can b
Tommaso de Fernex, Christopher D. Hacon
In this paper we generalize the definitions of singularities of pairs and multiplier ideal sheaves to pairs on arbitrary normal varieties, without any assumption on the variety being Q-Gorenstein or the pair being log Q-Gorenstein. The main features of the theory extend to this setting in a natural way.
Leandro G. Almeida, George Sterman, Werner Vogelsang
We study the QCD charge asymmetry in t\bar{t} production at the Tevatron. We investigate the role of higher orders in perturbation theory by considering the resummation of potentially large logarithmic corrections that arise near partonic threshold. This requires us to employ the rapidity-dependent anomalous dimension matrices that describe color mixing due
T. J. Booth, P. Blake, R. R. Nair, D. Jiang
The properties of suspended graphene are currently attracting enormous interest, but the small size of available samples and the difficulties in making them severely restrict the number of experimental techniques that can be used to study the optical, mechanical, electronic, thermal and other characteristics of this one-atom-thick material. Here we describe
Alejandro Egido, Giulio Ruffini, Marco Caparrini, Cristina Martin
The use of GNSS signals as a source of opportunity for remote sensing applications, GNSS-R, has been a research area of interest for more than a decade. One of the possible applications of this technique is soil moisture monitoring. The retrieval of soil moisture with GNSS-R systems is based on the variability of the ground dielectric properties associated t
Influence of the polarization in grazing scattering of fast hellium atoms from LiF(001) surfaces
physics.atom-phM. S. Gravielle, J. E. Miraglia
Grazing scattering of neutral atoms from insulator surfaces is investigated in the intermediate velocity range, in which interference effects have been recently observed. To describe this process we introduce a distorted-wave method, based on the use of the eikonal wave function, which takes into account the phase of the scattering state along the classical
Danny Calegari, Koji Fujiwara
A function on a discrete group is weakly combable if its discrete derivative with respect to a combing can be calculated by a finite state automaton. A weakly combable function is bicombable if it is Lipschitz in both the left and right invariant word metrics. Examples of bicombable functions on word-hyperbolic groups include (i) homomorphisms to Z (ii) word
Maurizio A. Bonuccelli, Francesca Lonetti, Francesca Martelli
Radio Frequency IDentification (RFID) systems are becoming more and more popular in the field of ubiquitous computing, in particular for objects identification. An RFID system is composed by one or more readers and a number of tags. One of the main issues in an RFID network is the fast and reliable identification of all tags in the reader range. The reader i
Erling J. Brynjolfsson, Larus Thorlacius
We use the global embedding of a black hole spacetime into a higher dimensional flat spacetime to define a local temperature for observers in free fall outside a static black hole. The local free-fall temperature remains finite at the event horizon and in asymptotically flat spacetime it approaches the Hawking temperature at spatial infinity. Freely falling
Superluminal problem in diffusion of relativistic particles and its phenomenological solution
astro-phR. Aloisio, V. Berezinsky, A. Gazizov
We discuss the superluminal problem in the diffusion of ultra high energy protons with energy losses taken into account. The phenomenological solution of this problem is found with help of the generalized Jüttner propagator, originally proposed for relativization of the Maxwellian gas distribution. It is demonstrated that the generalized Jüttner propagator g
Reference-less detection, astrometry, and photometry of faint companions with adaptive optics
astro-phSzymon Gladysz, Julian C. Christou
We propose a complete framework for the detection, astrometry, and photometry of faint companions from a sequence of adaptive optics corrected short exposures. The algorithms exploit the difference in statistics between the on-axis and off-axis intensity. Using moderate-Strehl ratio data obtained with the natural guide star adaptive optics system on the Lick
On the applicability of bosonization and the Anderson-Yuval methods at the strong-coupling limit of quantum impurity problems
cond-mat.str-elL. Borda, A. Schiller, A. Zawadowski
The applicability of bosonization and the Anderson-Yuval (AY) approach at strong coupling is investigated by considering two generic impurity models: the multichannel interacting resonant-level and the anisotropic Kondo models. The two methods differ in the renormalization of the conduction-electron density of states (DoS) near the impurity site. Reduction o
Vincent Bansaye
We consider a branching model for a population of dividing cells infected by parasites. Each cell receives parasites by inheritance from its mother cell and independent contamination from outside the population. Parasites multiply randomly inside the cell and are shared randomly between the two daughter cells when the cell divides. The law of the number of p
Massimo Marino
We investigate the possible existence of nonradiating motions of systems of point charges, according to classical electrodynamics with retarded potentials. We prove that two point particles of arbitrary electric charges cannot move for an infinitely long time within a finite region of space without radiating electromagnetic energy. We show however with an ex
Mohsen Alishahiha, Farhad Ardalan
We study 2D Maxwell-dilaton gravity on AdS(2). We distinguish two distinctive cases depending on whether the AdS(2) solution can be lifted to an AdS(3) geometry. In both cases, in order to get a consistent boundary condition we need to work with a twisted energy momentum tensor which has non-zero central charge. With this central charge and the explicit form
Pandelis Dodos, Jordi Lopez Abad, Stevo Todorcevic
We study the problem of the existence of unconditional basic sequences in Banach spaces of high density. We show, in particular, the relative consistency with GCH of the statement that every Banach space of density $\aleph_ω$ contains an unconditional basic sequence.
Leo van Iersel, Steven Kelk
A phylogenetic network is a directed acyclic graph that visualises an evolutionary history containing so-called reticulations such as recombinations, hybridisations or lateral gene transfers. Here we consider the construction of a simplest possible phylogenetic network consistent with an input set T, where T contains at least one phylogenetic tree on three l
Use of group theory and Clifford algebra in the study of generalized Dirac equation for particles with arbitrary spin
physics.gen-phI. I. Guseinov
Using condition of relativistic invariance, group theory and Clifford algebra the component Lorentz invariance generalized Dirac equation for a particle with arbitrary mass and spin is suggested, where In the case of half-integral spin particles, this equation is reduced to the sets of two-component independent matrix equations. It is shown that the relativi
Technical report: Adaptivity and optimality of the monotone least squares estimator for four different models
math.STEric Cator
In this paper we will consider the estimation of a monotone regression (or density) function in a fixed point by the least squares (Grenander) estimator. We will show that this estimator is fully adaptive, in the sense that the attained rate is given by a functional relation using the underlying function $f_0$, and not by some smoothness parameter, and that
Alexandre Noma, Ana B. V. Graciano, Luis Augusto Consularo, Roberto M. Cesar-Jr
This paper proposes a novel algorithm for the problem of structural image segmentation through an interactive model-based approach. Interaction is expressed in the model creation, which is done according to user traces drawn over a given input image. Both model and input are then represented by means of attributed relational graphs derived on the fly. Appear
Manfried Faber, Jeff Greensite, Urs M. Heller, Roman Höllwieser
We study correlations between center vortices and the low-lying eigenmodes of the Dirac operator, in both the overlap and asqtad formulations. In particular we address a puzzle raised some years ago by Gattnar et al. [Nucl. Phys. B 716, 105 (2005)], who noted that the low-lying Dirac eigenmodes required for chiral symmetry breaking do not appear to be presen
Satyabrata Bhattacharya, Suman Kumar Banik, Sudip Chattopadhyay, Jyotipratim Ray Chaudhuri
Based on a microscopic system reservoir model,where the associated bath is not in thermal equilibrium, we simulate the nonstationary Langevin dynamics and obtained the generalized nonstationary fluctuation dissipation relation (FDR) which asymptotically reduces to the traditional form. Our Langevin dynamics incorporates non-Markovian process also, the origin
L. Campanelli, P. Cea, G. L. Fogli
We analyze the generation of primordial magnetic fields during de Sitter inflation in a Lorentz-violating theory of Electrodynamics containing a Chern-Simons term which couples the photon to an external four-vector. We find that, for appropriate magnitude of the four-vector, the generated field is maximally helical and, through an inverse cascade caused by t
I. V. Panov, H. -Th. Janka
We study here the formation of heavy r-process nuclei in the high-entropy environment of rapidly expanding neutrino-driven winds from compact objects. In particular, we explore the sensitivity of the element creation in the A>130 region to the low-temperature behavior of the outflows. For this purpose we employ a simplified model of the dynamics and thermody
Biswajit Chakraborty, Jean Pierre Gazeau, Ahmed Youssef
The domain of application of quantization methods is traditionally restricted to smooth classical observables. We show that the coherent states or "anti-Wick" quantization enables us to construct fairly reasonable quantum versions of irregular observables living on the classical phase space, such as the angle function, the time function of a free par
Hajime Tsuji
In this article, we construct the canonical semipositive current or the canonical measure ($=$ the potential of the canonical semipositive current) on a smooth projective variety of nonnegative Kodaira dimension in terms of a dynamical system of Bergman kernels. This current is considered to be a generalization of a Kähler-Einstein metric and coincides the o
The extragalactic optical-infrared background radiations, their time evolution and the cosmic photon-photon opacity
astro-phAlberto Franceschini, Giulia Rodighiero, Mattia Vaccari
The background radiations in the optical and the infrared constitute a relevant cause of energy loss in the propagation of high energy particles through space. In particular, TeV observations with Cherenkov telescopes of extragalactic sources are influenced by the opacity effects due to the interaction of the very high-energy source photons with the backgrou
Patrick Popescu-Pampu, Jose Seade
Consider a fixed connected, finite graph $Γ$ and equip its vertices with weights $p_i$ which are non-negative integers. We show that there is a finite number of possibilities for the coefficients of the canonical cycle of a numerically Gorenstein surface singularity having $Γ$ as the dual graph of the minimal resolution, the weights $p_i$ of the vertices bei
Nikolaos Tetradis
The properties of strongly gravitating systems suggest that field theory overcounts the states of a system. Reducing the number of degrees of freedom, without abandoning the notion of effective field theory, may be achieved through a connection between the ultraviolet and infrared cutoffs. We provide an implementation of this idea within the Wilsonian approa
Ivan Calvo, Raul Sanchez, Benjamin A. Carreras
Fractional Levy motion (fLm) is the natural generalization of fractional Brownian motion in the context of self-similar stochastic processes and stable probability distributions. In this paper we give an explicit derivation of the propagator of fLm by using path integral methods. The propagators of Brownian motion and fractional Brownian motion are recovered
Fatihcan M. Atay, Sarika Jalan, Jürgen Jost
We use symbolic dynamics to study discrete-time dynamical systems with multiple time delays. We exploit the concept of avoiding sets, which arise from specific non-generating partitions of the phase space and restrict the occurrence of certain symbol sequences related to the characteristics of the dynamics. In particular, we show that the resulting forbidden
Huichao Song, Ulrich W. Heinz
Using numerical results from ideal and viscous relativistic hydrodynamic simulations with three different equations of state, for Au+Au and Cu+Cu collisions at different centralities and initial energy densities, we explore the dependence of the eccentricity-scaled elliptic flow, v_2/epsilon, and the produced entropy fraction, Delta S/S_0, on the final charg
Akira Ishida, Shunsuke Teraguchi
We reconstruct boundary superstring field theory via boundary states. After a minor modification of the fermionic two-form, all the equations needed for Batalin-Vilkovisky formulation are simply represented by closed string oscillators and the proof of gauge invariance is drastically simplified. The general form of the action of boundary superstring field th
Manuel Valiente, David Petrosyan
We consider a pair of bosonic particles in a one-dimensional tight-binding periodic potential described by the Hubbard model with attractive or repulsive on-site interaction. We derive explicit analytic expressions for the two-particle states, which can be classified as (i) scattering states of asymptotically free particles and (ii) interaction-bound dimer s
Thomas Aichele, Adrien Tribu, Catherine Bougerol, Kuntheak Kheng
We report on the growth of ZnSe nanowires and nano-needles using molecular beam epitaxy (MBE). Different growth regimes were found, depending on growth temperature and the Zn--Se flux ratio. By employing a combined MBE growth of nanowires and nano-needles without any post-processing of the sample, we achieved an efficient suppression of stacking fault defect
Atom Chip Diffraction of Bose-Einstein Condensates: The Role of Inter-Atomic Interactions
cond-mat.otherT. E. Judd, R. G. Scott, T. M. Fromhold
We use supercomputer simulations to show that inter-atomic interactions can strongly affect the phase evolution of Bose-Einstein condensates that are diffracted from atom chips, thereby explaining recent experiments. Interactions broaden and depopulate non-central diffraction orders and so, counter-intuitively, they actually reduce the spatial width of the d
J. L. Zdunik, M. Bejger, P. Haensel
We calculate parameters A and B of the Baym-Pines model of the hydro-elastic equilibrium of rotating neutron stars. Parameter A determines the energy increase of a non-rotating star due to a quadrupolar deformation of its shape. Parameter B determines residual quadrupolar deformation due to the crustal shear strain, in a neutron star that spun-down to a non-
Synthesis, Infra-red, Raman, NMR and structural characterization by X-ray Diffraction of [C12H17N2]2CdCl4 and [C6H10N2]2Cd3Cl10 compounds
cond-mat.mtrl-sciIskandar Chaabane, Faouzi Hlel, Kamel Guidara
The synthesis, infra-red, Raman and NMR spectra and crystal structure of 2, 4, 4- trimethyl-4, 5- dihydro-3H-benzo[b] [1, 4] diazepin-1-ium tetrachlorocadmate, [C12H17N2]2CdCl4 and benzene-1,2-diaminium decachlorotricadmate(II) [C6H10N2]2Cd3Cl10 are reported. The [C12H17N2]2CdCl4 compound crystallizes in the triclinic system (P-1 space group) with Z = 2 and
The role of the N*(1535) resonance and the pi^- p --> KY amplitudes in the OZI forbidden pi N --> phi N reaction
nucl-thM. Döring, E. Oset, B. S. Zou
We study the pi N --> phi N reaction close to the phi N threshold within the chiral unitary approach, by combining the pi^- p --> K^+ Sigma^-, pi^- p --> K^0 Sigma^0 and pi^- p --> K^0 Lambda amplitudes with the coupling of the phi to the K components of the final states of these reactions via quantum loops. We obtain a good agreement with experiment when th
Pierre Lescanne
In order to better understand reasoning involved in analyzing infinite games in extensive form, we performed experiments in the proof assistant Coq that are reported here.
T. Harko, W. F. Choi, K. C. Wong, K. S. Cheng
The emergence of the cosmological composition (the reheating era) after the inflationary period is analyzed in the framework of the braneworld models, in which our Universe is a three-brane embedded in a five-dimensional bulk, by assuming the possibility of the brane-bulk energy exchange. The inflaton field is assumed to decay into normal matter only, while
Entangled photon pairs from a quantum dot cascade decay: the effect of time-reordering
cond-mat.mes-hallF. Troiani, C. Tejedor
Coulomb interactions between confined carriers remove degeneracies in the excitation spectra of quantum dots. This provides a which path information in the cascade decay of biexcitons, thus spoiling the energy-polarization entanglement of the emitted photon pairs. We theoretically analyze a strategy of color coincidence across generation (AG), recently propo
S. A. Silotri, D. Angom, H. Mishra, Amruta Mishra
We discuss on the pairing mechanism of fermions with mismatch in their fermi momenta due to a mass asymmetry. Using a variational ansatz for the ground state we also discuss the BCS -BEC crossover of this system. It is shown that the breached pairing solution with a single fermi surface is stable in the BEC regime. We also include the temperatures effect on
Jorge Zanelli
The role of Chern-Simons (CS) actions is reviewed, starting from the observation that all classical actions in Hamiltonian form can be viewed as 0+1 CS systems, in the same class with the coupling between the electromagnetic field and a point charge. Some suggestions are derived that could shed some light on the quantization problem in D=2n-1>3 dimensions.
Spectral Energy Distribution of Radio Sources in Nearby Clusters of Galaxies: Implications for Sunyaev-Zel'dovich Effect Surveys
astro-phYen-Ting Lin, Bruce Partridge, J. C. Pober, Khadija El Bouchefry
To explore the high frequency radio spectra of galaxies in clusters, we used NRAO's Very Large Array at four frequencies, 4.9-43 GHz, to observe 139 galaxies in low redshift (z<0.25), X-ray detected, clusters. The clusters were selected from the survey conducted by Ledlow & Owen, who provided redshifts and 1.4 GHz flux densities for all the radio sources
A. E. Rastegin
Uncertainty relations for a pair of arbitrary measurements and for a single measurement are posed in the form of inequalities using the Renyi entropies. The formulation deals with discrete observables. Both the relations with state-dependent and state-independent bounds are presented. The entropic bounds are illustrated within the distinction between non-ort
D. Csontos, U. Zülicke, P. Brusheim, H. Q. Xu
We have analyzed theoretically the Zeeman splitting of hole-quantum-wire subband edges. As is typical for any bound state, their g factor depends on both an intrinsic g factor of the material and an additional contribution arising from a finite bound-state orbital angular momentum. We discuss the quantum-confinement-induced interplay between bulk-material an
One-dimensional anyons with competing $δ$-function and derivative $δ$-function potentials
cond-mat.stat-mechM. T. Batchelor, X. -W. Guan, A. Kundu
We propose an exactly solvable model of one-dimensional anyons with competing $δ$-function and derivative $δ$-function interaction potentials. The Bethe ansatz equations are derived in terms of the $N$-particle sector for the quantum anyonic field model of the generalized derivative nonlinear Schrödinger equation. This more general anyon model exhibits riche
Regularised Tripartite Continuous Variable EPR-type States with Wigner Functions and CHSH Violations
quant-phSol H. Jacobsen, P. D. Jarvis
We consider tripartite entangled states for continuous variable systems of EPR type, which generalise the famous bipartite CV EPR states (eigenvectors of conjugate choices X1 - X2, P1+ P2, of the systems' relative position and total momentum variables). We give the regularised forms of such tripartite EPR states in second-quantised formulation, and deriv
The MiniBooNE Collaboration
This article presents the compatibility of experimental data from neutrino oscillation experiments with a high-$\dmsq$ two-neutrino oscillation hypothesis. Data is provided by the Bugey, Karlsruhe Rutherford Medium Energy Neutrino Experiment 2 (KARMEN2), Los Alamos Liquid Scintillator Neutrino Detector (LSND), and MiniBooNE experiments. The LSND, KARMEN2, an
Alexander Engstrom
Cut ideals are used in algebraic statistics to study statistical models defined by graphs. Intuitively, topological restrictions on the graphs should imply structural statements about the corresponding cut ideals. Several theorems and many computer calculations support that. Sturmfels and Sullivant conjectured that the cut ideal is generated by quadrics if a
Jiri Lebl
We study singular real-analytic Levi-flat hypersurfaces in complex projective space. We define the rank of an algebraic Levi-flat hypersurface and study the connections between rank, degree, and the type and size of the singularity. In particular, we study degenerate singularities of algebraic Levi-flat hypersurfaces. We then give necessary and sufficient co
Andrew Kricker, Daniel Moskovich
We consider knots equipped with a representation of their knot groups onto a dihedral group D_{2n} (where n is odd). To each such knot there corresponds a closed 3-manifold, the (irregular) dihedral branched covering space, with the branching set over the knot forming a link in it. We report a variety of results relating to the problem of passing from the in
Hyerim Noh, Jai-chan Hwang
Is Newton's gravity sufficient to handle the weakly nonlinear evolution stages of the cosmic large-scale structures? Here we resolve the issue by analytically deriving the density and velocity power spectra to the second order in the context of Einstein's gravity. The recently found pure general relativistic corrections appearing in the third-order p
Universality in the Large N_c Dynamics of Flavour: Thermal Vs. Quantum Induced Phase Transitions
hep-thVeselin G. Filev, Clifford V. Johnson
We show how two important types of phase transition in large N_c gauge theory with fundamental flavours can be cast into the same classifying framework as the meson-melting phase transition. These are quantum fluctuation induced transitions in the presence of an external electric field, or a chemical potential for R-charge. The classifying framework involves
Lisandro J. Fermin
The aim of this paper is to extend the aggregation convergence results given in (Dacunha-Castelle and Fermin 2005, Dacunha-Castelle and Fermin 2008) to doubly stochastic linear and nonlinear processes with weakly dependent innovations. First, we introduce a weak dependence notion for doubly stochastic processes, based in the weak dependence definition given
Svend Erik Rugh, Henrik Zinkernagel
In this manuscript we initiate a systematic examination of the physical basis for the time concept in cosmology. We discuss and defend the idea that the physical basis of the time concept is necessarily related to physical processes which could conceivably take place among the material constituents available in the universe. It is common practice to link the
E. Sauvan
The high energy program of the HERA collider ended in March 2007. In total the H1 and ZEUS experiments collected an integrated luminosity of about 1 fb$^{-1}$. Recent results of model independent searches for new physics from both experiments are presented. Specifically, studies of the events with an isolated lepton and missing transverse momentum and multi-
Commissioning of CMS and early standard model measurements with jets, missing transverse energy and photons at the LHC
hep-exT. Christiansen
We report on the status and history of the CMS commissioning, together with selected results from cosmic-ray muon data. The second part focuses on strategies for optimizing the reconstruction of jets, missing transverse energy and photons for early standard model measurements at ATLAS and CMS with the first collision data from the Large Hadron Collider at CE
Bradley W. Hindman, Rekha Jain
Recent observations of coronal-loop waves by TRACE and within the corona as a whole by CoMP clearly indicate that the dominant oscillation period is 5 minutes, thus implicating the solar p modes as a possible source. We investigate the generation of tube waves within the solar convection zone by the buffeting of p modes. The tube waves--in the form of longit
A. De Rosa, L. Bassani, P. Ubertini, A. Malizia
We present the broadband analysis of the powerful quasar 4C04.42 (z=0.965) observed by XMM and INTEGRAL. The 0.2--200 keV spectrum is well reproduced with a hard power-law component ($Γ\sim$1.2), augmented by a soft component below 2 keV (observer frame), which is described by a thermal blackbody with temperature kT$\backsimeq$ 0.15 keV. Alternatively, a bro
Todd D. Beaudet, Michele Casula, Jeongnim Kim, Sandro Sorella
We present a quantum Monte Carlo study of the hydrogen-benzene system where binding is very weak. We demonstrate that the binding is well described at both variational Monte Carlo (VMC) and diffusion Monte Carlo (DMC) levels by a Jastrow correlated single determinant geminal wave function with an optimized compact basis set that includes diffuse orbitals. Ag
The Role of Electrical and Thermal Contact Resistance for Joule Breakdown of Single-Wall Carbon Nanotubes
cond-mat.mes-hallEric Pop
Several data sets of electrical breakdown in air of single-wall carbon nanotubes (SWNTs) on insulating substrates are collected and analyzed. A universal scaling of the Joule breakdown power with nanotube length is found, which appears independent of the insulating substrates used or their thickness. This suggests the thermal resistances at the interface bet
Hendrik De Bie
A superspace version of the Schrödinger equation with a delta potential is studied using Fourier analysis. An explicit expression for the energy of the single bound state is found as a function of the super-dimension M in case M is smaller than or equal to 1. In the case when there is one commuting and 2n anti-commuting variables also the wave function is gi
Claudia del P. Lagos, Sofia A. Cora, Nelson D. Padilla, .
We study the effects of Active Galactic Nuclei (AGN) feedback on the formation and evolution of galaxies in a semi-analytic model of galaxy formation. This model is an improved version of the one described by Cora (2006), which now considers the growth of black holes (BHs) as driven by (i) gas accretion during merger-driven starbursts and mergers with other
Cristina Espana-Bonet, Pilar Ruiz-Lapuente
We investigate the equation of state w(z) in a non-parametric form using the latest compilations of distance luminosity from SNe Ia at high z. We combine the inverse problem approach with a Monte Carlo to scan the space of priors. On the light of these high redshift supernova data sets, we reconstruct w(z). A comparison between a sample including the latest
Rosemary A. Mardling
In order to explain the significant orbital eccentricity of the short-period transiting Neptune-mass planet GJ 436b and at the same time satisfy various observational constraints and anomalies, Ribas, Font-Ribera and Beaulieu have proposed the existence of an eccentric low-mass companion planet at the position of the outer 2:1 resonance. The authors demonstr
M. E. Cates, S. M. Fielding, D. Marenduzzo, E. Orlandini
We study numerically the rheological properties of a slab of active gel close o the isotropic-nematic transition. The flow behavior shows strong dependence on sample size, boundary conditions, and on the bulk constitutive curve, which, on entering the nematic phase, acquires an activity-induced discontinuity at the origin. The precursor of this within the me
Rustem Khasanov, Hubertus Luetkens, Alex Amato, Hans-Henning Klauss
Measurements of the in-plane magnetic field penetration depth λ_{ab} in Fe-based superconductors with the nominal composition SmFeAsO_0.85 (T_c\simeq52K) and NdFeAsO_0.85 (T_c\simeq51K) were carried out by means of muon-spin-rotation. The absolute values of λ_{ab} at T=0 were found to be 189(5)nm and 195(5)nm for Sm and Nd substituted samples, respectively.
Getting Lucky with Adaptive Optics: Fast AO Image Selection in the Visible with a Large Telescope
astro-phN. M. Law, C. D. Mackay, R. G. Dekany, M. Ireland
We describe the results from a new instrument which combines Lucky Imaging and Adaptive Optics to give the first routine direct diffraction-limited imaging in the visible on a 5m telescope. With fast image selection behind the Palomar AO system we obtained Strehl ratios of 5-20% at 700 nm in a typical range of seeing conditions, with a median Strehl of appro
R. Della Ceca, A. Caccianiga, P. Severgnini, T. Maccacaro
(ABRIDGED) We investigate here the XLF of absorbed (Nh between 4E21 and E24 cm-2) and unabsorbed (Nh < 4E21 cm-2) AGN, the fraction of absorbed AGN as a function of Lx (and z), the intrinsic Nh distribution of the AGN population, and the XLF of Compton Thick (Nh > E24 cm-2) AGN. To carry out this investigation we have used the XMM-Newton Hard Bright Serendip
Hendrik De Bie
In this paper extensions of the classical Fourier, fractional Fourier and Radon transforms to superspace are studied. Previously, a Fourier transform in superspace was already studied, but with a different kernel. In this work, the fermionic part of the Fourier kernel has a natural symplectic structure, derived using a Clifford analysis approach. Several bas
J. B. Sokoloff
It is shown on the basis of scaling arguments that a disordered interface between two elastic solids will quite generally exhibit static and "dry friction" (i.e., kinetic friction which does not vanish as the sliding velocity approaches zero), because of Tomlinson model instabilities that occur for small length scale asperities. This provides a possi
W. D. Kulp, J. L. Wood, P. E. Garrett, C. Y. Wu
The 685 keV excitation energy of the first excited 0+ state in 152Sm makes it an attractive candidate to explore expected two-phonon excitations at low energy. Multiple-step Coulomb excitation and inelastic neutron scattering studies of 152Sm are used to probe the E2 collectivity of excited 0+ states in this "soft" nucleus and the results are compare
Pavel Etingof, John Kim, Xiaoguang Ma
We study the quotient Q_i(A) of a free algebra A by the ideal M_i(A) generated by relation that the i-th commutator of any elements is zero. In particular, we completely describe such quotient for i=4 (for i<=3 this was done previously by Feigin and Shoikhet). We also study properties of the ideals M_i(A), e.g. when M_i(A)M_j(A) is contained in M_{i+j-1}(A)
Cenalo Vaz, K. R. Koehler
We present exact solutions describing rotating, inhomogeneous dust with generic initial data in 2+1 dimensional AdS spacetime and show how they are smoothly matched to the Banados-Teitelboim-Zanelli (BTZ) solution in the exterior. The metrics, which are the rotational analogues of the 2+1 dimensional LeMaitre-Tolman-Bondi (LTB) family, are described by their
Maxim Krikun
We show that the Schaeffer's tree for an infinite quadrangulation only changes locally when changing the root of the quadrangulation. This follows from one property of distances in the infinite uniform random quadrangulation.
Giuseppe Da Prato, Arnaud Debussche
We consider the martingale problem associated to the Navier-Stokes in dimension 2 or 3. Existence is well known and it has been recently shown that markovian transition semi group associated to these equations can be constructed. We study the Kolmogorov operator associated to these equations. It can be defined formally as a differential operator on an infini
H. Esbensen
Fusion data for $^{16}$O+$^{16}$O are analyzed by coupled-channels calculations. It is shown that the calculated cross sections are sensitive to the couplings to the $2^+$ and $3^-$ excitation channels even at low energies, where these channels are closed. The sensitivity to the ion-ion potential is investigated by applying a conventional Woods-Saxon potenti
F. Cianfrani, G. Montani
We discuss properties of particles and fields in a multi-dimensional space-time, where the geometrization of gauge interactions can be performed. As far as spinors are concerned, we outline how the gauge coupling can be recognized by a proper dependence on extra-coordinates and by the dimensional reduction procedure. Finally applications to the Electro-Weak
F. Cianfrani, G. Montani
The implications of restricting the covariance principle within a Gaussian gauge are developed both on a classical and a quantum level. Hence, we investigate the cosmological issues of the obtained Schrödinger Quantum Gravity with respect to the asymptotically early dynamics of a generic Universe. A dualism between time and the reference frame fixing is then
Enrique Cobas, Michael S. Fuhrer
Carbon nanotube Schottky diodes have been fabricated in an all-photolithographic process using dissimilar contact metals on high-frequency compatible substrates (quartz and sapphire). Diodes show near-ideal behavior, and rectify currents of up to 100 nA and at frequencies up to 18 GHz. The voltage and frequency dependence is used to estimate the junction cap
A. T. Araudo, G. E. Romero, V. Bosch-Ramon, J. M. Paredes
Recent radio observations support a picture for star formation where there is accretion of matter onto a central protostar with the ejection of molecular outflows that can affect the surrounding medium. The impact of a supersonic outflow on the ambient gas can produce a strong shock that could accelerate particles up to relativistic energies. A strong eviden
G. Pupillo, A. Micheli, H. P. Büchler, P. Zoller
In this review chapter we focus on the many-body dynamics of cold polar molecules in the strongly interacting regime. In particular, we discuss a toolbox for engineering many-body Hamiltonians based on the manipulation of the electric dipole moments of the molecules, and thus of molecular interactions, using external static and microwave fields. This forms t
Hubble Space Telescope Imaging of Bright Lyman-break Galaxy Candidates from the Sloan Digital Sky Survey: Not LBGs After All
astro-phMisty C. Bentz, Richard W. Pogge, Patrick S. Osmer
We present deep Hubble Space Telescope ACS and NICMOS images of six bright Lyman-break galaxy candidates that were previously discovered in the Sloan Digital Sky Survey. We find that five of the objects are consistent with unresolved point sources. Although somewhat atypical of the class, they are most likely LoBAL quasars, perhaps FeLoBALs. The sixth object
W. Calvert, D. Cenzer, V. S. Harizanov, A. Morozov
Let p be a fixed prime. An Abelian p-group is an Abelian group (not necessarily finitely generated) in which every element has for its order some power of p. The countable Abelian p-groups are classified by Ulm's theorem, and Khisamiev characterized the Abelian p-groups with computable copies. A computable structure A is said to be $Δ^0_α$ categorical if
W. Calvert, D. Cenzer, V. S. Harizanov, A. Morozov
An equivalence structure is a set with a single binary relation, satisfying sentences stating that the relation is an equivalence relation. A computable structure A is said to be $Δ^0_α$ categorical if for any computable structure B isomorphic to A there is a $Δ^0_α$ function witnessing that the two are isomorphic. The present paper gives an exact characteri
Vadim Zaliva
In this paper we will discuss the design of abstract firewall model along with platform-independent policy definition language. We will also discuss the main design challenges and solutions to these challenges, as well as examine several differences in policy semantics between vendors and how it could be mapped to our platform-independent language. We will a
A. R. Yeates, D. H. Mackay, A. A. van Ballegooijen
Current helicity quantifies the location of twisted and sheared non-potential structures in a magnetic field. We simulate the evolution of magnetic fields in the solar atmosphere in response to flux emergence and shearing by photospheric motions. In our global-scale simulation over many solar rotations the latitudinal distribution of current helicity develop
Tim Christiansen
The CMS detector is under construction for imminent operation at the Large Hadron Collider at CERN near Geneva, Switzerland. The installation and commissioning is performed in a surface hall. Thereafter, all the main heavy elements of the detector, the disks and wheels, are lowered in the experimental cavern starting at the end of 2006. The superconducting m
Alan Heavens
In this brief review I consider the advances made in weak gravitational lensing over the last 8 years, concentrating on the large scales - cosmic shear. I outline the theoretical developments, observational status, and the challenges which cosmic shear must overcome to realise its full potential. Finally I consider the prospects for probing Dark Energy and e
Ann Lemahieu, Lise Van Proeyen
The local topological zeta function is a rational function associated to a germ of a complex holomorphic function. This function can be computed from an embedded resolution of singularities of the germ. For nondegenerate functions it is also possible to compute it from the Newton polyhedron. Both ways give rise to a set of candidate poles of the topological
Ann Lemahieu, Lise Van Proeyen
The holomorphy conjecture predicts that the local Igusa zeta function associated to a hypersurface and a character is holomorphic on $\mathbb{C}$ whenever the order of the character does not divide the order of any eigenvalue of the local monodromy of the hypersurface. In this note we propose the holomorphy conjecture for arbitrary subschemes at the level of
K. Benakli, M. D. Goodsell
We compute the two-point functions for chiral matter states in toroidal intersecting D6-brane models. In particular, we provide the techniques to calculate Moebius strip diagrams including the worldsheet instanton contribution.