July 2009 arXiv papers — page 47

Shu-Chiuan Chang, Robert Shrock

We determine the general structure of the partition function of the $q$-state Potts model in an external magnetic field, $Z(G,q,v,w)$ for arbitrary $q$, temperature variable $v$, and magnetic field variable $w$, on cyclic, Möbius, and free strip graphs $G$ of the square (sq), triangular (tri), and honeycomb (hc) lattices with width $L_y$ and arbitrarily grea

Patrick Brosnan, Zinovy Reichstein, Angelo Vistoli, Najmuddin Fakhruddin

In this paper we address questions of the following type. Let k be a base field and K/k be a field extension. Given a geometric object X over a field K (e.g. a smooth curve of genus g) what is the least transcendence degree of a field of definition of $X$ over the base field k? In other words, how many independent parameters are needed to define X? To study

Julien Randon-Furling, Satya N. Majumdar, Alain Comtet

We compute exactly the mean perimeter and area of the convex hull of N independent planar Brownian paths each of duration T, both for open and closed paths. We show that the mean perimeter < L_N > = α_N, \sqrt{T} and the mean area <A_N> = β_N T for all T. The prefactors α_N and β_N, computed exactly for all N, increase very slowly (logarithmically) with incr

Norihiko Minami

We compute the &#34;moments&#34; and its continuous analogue of the random variable $\N \ni l \mapsto \gcd(l,n_1) \gcd(l, n_2) ... \gcd(l, n_k) \in \N$ by a purely elementary method. This generalizes a result of Deitmar-Koyama-Kurokawa, which computed its &#34;average&#34; using some analysis involving L-function. We show this average is nothing but the inva

Kohei Yoshida

Measurement of Higgs branching ratio is necessary to investigate Higgs coupling to particle masses. Especially, it is the most important program to measure the branching ratio of H->bb and H->cc at the international linear collider (ILC). We have studied the measurement accuracy of Higgs branching ratio at ILC with Sqrt(s) = 250 GeV by using ZH->vvH events.

Y. Kabashima, T. Wadayama, T. Tanaka

We consider the problem of reconstructing an $N$-dimensional continuous vector $\bx$ from $P$ constraints which are generated by its linear transformation under the assumption that the number of non-zero elements of $\bx$ is typically limited to $ρN$ ($0\le ρ\le 1$). Problems of this type can be solved by minimizing a cost function with respect to the $L_p$-

Dorin Popescu, Muhammad Imran Qureshi

Let $Q$ and $Q&#39;$ be two monomial primary ideals of a polynomial algebra $S$ over a field. We give an upper bound for the Stanley depth of $S/(Q\cap Q&#39;)$ which is reached if $Q$,$Q&#39;$ are irreducible. Also we show that Stanley&#39;s Conjecture holds for $Q_1\cap Q_2$, $S/(Q_1\cap Q_2\cap Q_3)$, $(Q_i)_i$ being some irreducible monomial ideals of $S

Varun Awasthi, Yogesh M Joshi

We have studied the effect of temperature on aging dynamics of laponite suspensions by carrying out the rheological oscillatory and creep experiments. We observed that at higher temperatures the mechanism responsible for aging became faster thereby shifting the evolution of elastic modulus to lower ages. Significantly, in the creep experiments, all the aging

Yu-Xiao Liu, Chun-E Fu, Li Zhao, Yi-Shi Duan

A three-parameter (positive odd integer $s$, thickness factor $λ$, and asymmetry factor $a$) family of asymmetric thick brane solutions in five dimensions were constructed from a two-parameter ($s$ and $λ$) family of symmetric ones in [R. Guerrero, R.O. Rodriguez, and R. Torrealba, Phys. Rev. D \textbf{72}, 124012 (2005).]. The values $s=1$ and $s\geq3$ corr

Sariel Har-Peled

We present a simple randomized incremental algorithm for building compressed quadtrees. The resulting algorithm seems to be simpler than previously known algorithms for this task.

Anan Fang, Thomas Koschny, Costas M Soukoulis

A self-consistent computational scheme is presented for one dimensional (1D) and two dimensional (2D) metamaterial systems with gain incorporated into the nanostructures. The gain is described by a generic four-level system. The loss compensation and the lasing behavior of the metamaterial system with gain are studied. A critical pumping rate exists for comp

Yanling Shao, Jian Shen, Yubin Gao

In this paper, we study the kth upper bases of primitive non-powerful signed digraphs. A bound on the kth upper bases of all primitive non-powerful signed digraphs is obtained, and the equality case of the bound is characterized. We also show that there exists &#34;gap&#34; in the kth upper base set of primitive non-powerful signed digraphs.

Jiangfeng Zhou, Jianfeng Dong, Thomas Koschny, Maria Kafesaki

We demonstrate experimentally and numerically that metamaterials based on bilayer cross wires give giant optical activity, circular dichroism, and negative refractive index. The presented chiral design offers a much simpler geometry and more efficient way to realize negative refractive index at any frequency. We also developed a retrieval procedure for chira

Jiangfeng Zhou, Thomas Koschny, Maria Kafesaki, Costas M. Soukoulis

e present a detailed study of the retrieved optical parameters, electrical permittivity, magnetic permeability and refractive index, of the coupled fishnet metamaterial structures as a function of the separation between layers. For the weak coupling case, the retrieved parameters are very close to the one-functional-layer results and converge relatively fast

Ciprian Tudor

Using recent results on the behavior of multiple Wiener-Itô integrals based on Stein&#39;s method, we prove Hsu-Robbins and Spitzer&#39;s theorems for sequences of correlated random variables related to the increments of the fractional Brownian motion.

Thiago O. Maciel, Reinaldo O. Vianna

We explore procedures to detect entanglement of unknown mixed states, which can be experimentally viable. The heart of the method is a hierarchy of simple feasibility problems, which provides sufficient conditions to entanglement. Our numerical investigations indicate that the entanglement is detected with a cost which is much lower than full state tomograph

Anan Fang, Thomas Koschny, Costas M. Soukoulis

We design three-dimensional (3D) metallic nanowire media with different structures and numerically demonstrate that they can be homogeneous effective indefinite anisotropic media by showing that their dispersion relations are hyperbolic. For a finite slab, a nice fitting procedure is exploited to obtain the dispersion relations from which we retrieve the eff

S. Tongay, J. Hwang, D. B. Tanner, H. K. Pal

Exposure of highly oriented pyrolytic graphite to bromine vapor gives rise to in-plane charge conductivities which increase monotonically with intercalation time toward values (for ~6 at% Br) that are significantly higher than Cu at temperatures down to 5 K. Magnetotransport, optical reflectivity and magnetic susceptibility measurements confirm that the Br d

Nikos Bagis

In this note we evaluate multiple integrals that play a crucial role in the theory of irrationality of zeta function

Nicolae Manolache

We give the construction of a class of multiple locally complete intersection structures on a smooth algebraic variety as support. This class contains the structures defined locally by equations of the form $x^n=0$, $y^2=0$, $z=0, >..., u=0$.

Rossen I. Ivanov

Integrable equations with second order Lax pair like KdV and Camassa-Holm (CH) exhibit interesting conformal properties and can be written in terms of the so-called conformal invariants (Schwarz form). These properties for the CH hierarchy are discussed in this contribution. The squared eigenfunctions of the spectral problem, associated to the Camassa-Holm e

Mihai Patrascu

The rank problem in succinct data structures asks to preprocess an array A[1..n] of bits into a data structure using as close to n bits as possible, and answer queries of the form rank(k) = Sum_{i=1}^k A[i]. The problem has been intensely studied, and features as a subroutine in a majority of succinct data structures. We show that in the cell probe model wit

Rennan Barkana, Abraham Loeb

Gravitational lensing observations of massive X-ray clusters imply a steep characteristic density profile marked by a central concentration of dark matter. The observed mass fraction within a projected radius of 150 kpc is twice that found in state-of-the-art dark matter simulations of the standard Lambda-CDM cosmology. A central baryon enhancement that coul

Niranjay Ravindran, Nihar Jindal

In a multiple transmit antenna, single antenna per receiver downlink channel with limited channel state feedback, we consider the following question: given a constraint on the total system-wide feedback load, is it preferable to get low-rate/coarse channel feedback from a large number of receivers or high-rate/high-quality feedback from a smaller number of r

D. Kranich, D. Paneque, A. Cesarini, A. Falcone

The well-studied VHE (E >100 GeV) blazar Mrk 501 was observed between March and May 2008 as part of an extensive multiwavelength observation campaign including radio, optical, X-ray and VHE gamma-ray instruments. Mrk 501 was in a low state of activity during the campaign, with a low VHE flux of about 20% the Crab Nebula flux. Nevertheless, significant flux v

A. L. Subasi, S. Sevincli, P. Vignolo, B. Tanatar

Using mean-field theory, we study the equilibrium properties of boson-fermion mixtures confined in a harmonic pancake-shaped trap at zero temperature. When the modulus of the s-wave scattering lengths are comparable to the mixture thickness, two-dimensional scattering events introduce a logarithmic dependence on density in the coupling constants, greatly mod

Łukasz Marcinowski, Katarzyna Roszak, Paweł Machnikowski

We discuss pure dephasing of singlet-triplet superpositions in two-electron double quantum dots due to elastic phonon scattering. We generalize our previous results to a system built of two non-identical dots. We show that the asymmetry must be very strong in order to considerably affect the dephasing rate.

Nikos Bagis

In this work we derive results concerning Elliptic Functions using as tools general formulas from previus work.

C. J. Cyganowski, C. L. Brogan, T. R. Hunter, E. Churchwell

We present the results of a high angular resolution Very Large Array (VLA) Class I 44 GHz and Class II 6.7 GHz methanol maser survey of a sample of ~20 massive young stellar object (MYSO) outflow candidates selected on the basis of extended 4.5 micron emission in Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) images. These 4.5 mic

Jeff Wagg, Emmanuel Momjian

We present Expanded Very Large Array and Arecibo observations of two lensed submm galaxies at z~2.5, in order to search for redshifted 22.235 GHz water megamaser emission. Both SMM J14011+0252 and SMM J16359+6612 have multi-wavelength characteristics consistent with ongoing starburst activity, as well as CO line emission indicating the presence of warm molec

Jenny E. Greene, Nadia L. Zakamska, Xin Liu, Aaron J. Barth

Obscured or narrow-line active galaxies offer an unobstructed view of the quasar environment in the presence of a luminous and vigorously accreting black hole. We exploit the large new sample of optically selected luminous narrow-line active galaxies from the Sloan Digital Sky Survey at redshifts 0.1 < z < 0.45, in conjunction with follow-up observations wit

J. A. Hodge, G. R. Zeimann, R. H. Becker, R. L. White

We detect and study the properties of faint radio AGN in Luminous Red Galaxies (LRGs). The LRG sample comprises 760,000 objects from a catalog of LRG photometric redshifts constructed from the Sloan Digital Sky Survey (SDSS) imaging data, and 65,000 LRGs from the SDSS spectroscopic sample. These galaxies have typical 1.4 GHz flux densities in the 10s-100s of

Matt Gibson, Gaurav Kanade, Erik Krohn, Kasturi Varadarajan

We consider the problem of tracking $n$ targets in the plane using $2n$ cameras. We can use two cameras to estimate the location of a target. We are then interested in forming $n$ camera pairs where each camera belongs to exactly one pair, followed by forming a matching between the targets and camera pairs so as to best estimate the locations of each of the

Paulo E. G. Assis, Andreas Fring

We provide a novel procedure to obtain complex PT-symmetric multi-particle Calogero systems. Instead of extending or deforming real Calogero systems, we explore here the possibilities for complex systems to arise from real nonlinear field equations. We exemplify this procedure for the Boussinesq equation and demonstrate how singularities in real valued wave

M. C. Bertin, B. M. Pimentel, G. E. R. Zambrano

In this work we will develop the canonical structure of Podolsky&#39;s generalized electrodynamics on the null-plane. This theory has second-order derivatives in the Lagrangian function and requires a closer study for the definition of the momenta and canonical Hamiltonian of the system. On the null-plane the field equations also demand a different analysis

W. Selke, G. Bannasch, M. Holtschneider, I. P. McCulloch

We study classical and quantum Heisenberg antiferromagnets with exchange anisotropy of XXZ-type and crystal field single-ion terms of quadratic and cubic form in a field. The magnets display a variety of phases, including the spin-flop (or, in the quantum case, spin-liquid) and biconical (corresponding, in the quantum lattice gas description, to supersolid)

J. Sauter, S. Wolf, R. Launhardt, D. L. Padgett

Circumstellar discs are expected to be the nursery of planets. Grain growth within such discs is the first step in the planet formation process. The Bok globule CB 26 harbours such a young disc. We present a detailed model of the edge-on circumstellar disc and its envelope in the Bok globule CB 26. The model is based on HST near-infrared maps in the I, J, H,

H. Tian, C. -Y. Tu, L. -D. Xia, J. -S. He

The radiance and Doppler-shift distributions across the solar network provide observational constraints of two-dimensional modeling of transition-region emission and flows in coronal funnels. Two different methods, dispersion plots and average-profile studies, were applied to investigate these distributions. In the dispersion plots, we divided the entire sca

Anthony Réveillac

In this Note we consider a quadratic backward stochastic differential equation (BSDE) driven by a continuous martingale $M$ and whose generator is a deterministic function. We prove (in Theorem \ref{theorem:main}) that if $M$ is a strong homogeneous Markov process and if the BSDE has the form \eqref{BSDE} then the unique solution $(Y,Z,N)$ of the BSDE is red

H. Tian, W. Curdt, E. Marsch, U. Schuehle

We extend earlier work by studying in the quiet Sun the line profiles of the hydrogen Lyman-alpha and Lyman-beta lines, which were obtained quasi-simultaneously in a raster scan near disk center. The self-reversal depths of the Ly-a and Ly-b profiles are quantified by measuring the maximum spectral radiances of the two horns and the minimum spectral radiance

Andre M. C. Souza, Francisco A. G. Almeida

We show that the thermal entanglement in a spin system using only magnetic susceptibility measurements is restricted to the insulator materials. We develop a generalization of the thermal entanglement witness that allows us to get information about the system entanglement with variable local spin lengths that can be used experimentally in conductor or insula

Marta Lewicka, Piotr B. Mucha

We extend earlier work on traveling waves in premixed flames in a gravitationally stratified medium, subject to the Boussinesq approximation. For three-dimensional channels not aligned with the gravity direction and under the Dirichlet boundary conditions in the fluid velocity, it is shown that a non-planar traveling wave, corresponding to a non-zero reactio

Ramasuri Narayanam, Y. Narahari

Nodes in an ad hoc wireless network incur certain costs for forwarding packets since packet forwarding consumes the resources of the nodes. If the nodes are rational, free packet forwarding by the nodes cannot be taken for granted and incentive based protocols are required to stimulate cooperation among the nodes. Existing incentive based approaches are base

Jose A. Diaz-Garcia, Ramon Gutiérrez Jáimez

Some tools and ideas are interchanged between random matrix theory and multivariate statistics. In the context of the random matrix theory, classes of spherical and generalised Wishart random matrix ensemble, containing as particular cases the classical random matrix ensembles, are proposed. Some properties of these classes of ensemble are analysed. In addit

Pedro Sancho, Luis Plaja

We analyse the influence of entanglement on the emission properties of atoms. To this end, first, we propose a scheme for the preparation of a pair of entangled Helium atoms, one in the ortho and the other in the para spin configuration. We discuss a realistic scenario for this process, based in the double ionization of He by intense laser fields. These stat

G. Gogoberidze, S. M. Mahajan, S. Poedts

It is shown that in the framework of the weak turbulence theory, the autocorrelation and cascade timescales are always of the same order of magnitude. This means that, contrary to the general belief, any model of turbulence which implies a large number of collisions among wave packets for an efficient energy cascade (such as the Iroshnikov-Kraichnan model) a

Ricardo Lima, Arnaud Meyroneinc, Edgardo Ugalde

We study the dynamical properties of small regulatory networks treated as non autonomous dynamical systems called modules when working inside larger networks or, equivalently when subject to external signal inputs. Particular emphasis is put on the interplay between the internal properties of the open systems and the different possible inputs on them to dedu

M. M. Sharma, J. K. Sharma

N=Z nuclei above Ni are understood to be waiting-point nuclei in the rp-process nucleosynthesis. Investigating the experimental isotope shifts in Kr isotopes near the proton drip-line, we have discovered that N=Z rp-process nuclei $^{68}$Se, $^{72}$Kr, $^{76}$Sr and $^{80}$Zr exhibit a significant shell gap both at the proton and neutron numbers in the defor

M. B. Erdogan, N. Tzirakis, V. Zharnitsky

Near linear evolution in Korteweg de Vries (KdV) equation with periodic boundary conditions is established under the assumption of high frequency initial data. This result is obtained by the method of normal form reduction.

Arsham Farzinnia, Duane A. Dicus, Wayne W. Repko, Todd M. Tinsley

In a previous paper, we showed that the decay rate of a muon is only slightly affected by the presence of a circularly polarized laser and we gave an analytic expression for the correction. In this paper, we present the analytical result for the case of a linearly polarized laser. Again the effect of the laser is small.

M. I. Kumsiashvili, K. B. Chargeishvili

Results of three-color photoelectric UBV observations of UU Cas performed at Abastumani Astrophysical Observatory in 1972-1984 are presented.

T. Duguet, T. Lesinski

First, we briefly outline some aspects of the starting project to design non-empirical energy functionals based on low-momentum vacuum interactions and many-body perturbation theory. Second, we present results obtained within an approximation of such a scheme where the pairing part of the energy density functional is constructed at first order in the nuclear

Lucas Lacasa, Miguel Cea, Massimiliano Zanin

In this work we present a model of an air transportation traffic system from the complex network modelling viewpoint. In the network, every node corresponds to a given airport, and two nodes are connected by means of flight routes. Each node is weighted according to its load capacity, and links are weighted according to the Euclidean distance that separates

A. A. Shylau, J. W. Klos, I. V. Zozoulenko

We present an analytical theory for the gate electrostatics and the classical and quantum capacitance of the graphene nanoribbons (GNRs) and compare it with the exact self-consistent numerical calculations based on the tight-binding p-orbital Hamiltonian within the Hartree approximation. We demonstrate that the analytical theory is in a good qualitative (and

J. F. Carinena, X. Gracia, E. Martinez, G. Marmo

We present a new setting of the geometric Hamilton-Jacobi theory by using the so-called time-evolution operator K. This new approach unifies both the Lagrangian and the Hamiltonian formulation of the problem developed in a previous paper [7], and can be applied to the case of singular Lagrangian dynamical systems.

Alexander Stoimenow

It is a conjecture that the signature of a positive link is bounded below by an increasing function of its negated Euler characteristic. In relation to this conjecture, we apply the generator description for canonical genus to show that the boundedness of the genera of positive knots with given signature can be algorithmically partially decided. We relate th

Ke Zhang, Biwei Jiang, Aigen Li

A large number of carbon-rich evolved objects (asymptotic giant branch stars, protoplanetary nebulae, and planetary nebulae) in both the Milky Way galaxy and the Magellanic Clouds exhibit an enigmatic broad emission feature at 30 micron. This feature, extending from 24 micron to 45 micron, is very strong and accounts for up to 30% of the total infrared lumin

Nataly Tyurina, Vladimir Lipunov, Victor Kornilov, Evgeny Gorbovskoy

There are the results of gamma-ray bursts observations obtained using the MASTER robotic telescope in 2007 - 2009. We observed 20 error-boxes of gamma-ray bursts this period.The limits on their optical brightnesses have been derived. There are 5 prompt observations among them, obtained at our very wide field cameras. Also we present the results of the earlie

Cecilia Fariña, Guillermo L. Bosch, Nidia I. Morrell, Rodolfo H. Barbá

We present a spectroscopic study of the N159/N160 massive-star forming region south of 30 Doradus in the Large Magellanic Cloud, classifying a total of 189 stars in the field of the complex. Most of them belong to O and early B spectral classes; we have also found some uncommon and very interesting spectra, including members of the Onfp class, a Be P Cygni s

F. Becattini, R. Fries

We review the foundations and the applications of the statistical and the quark recombination model as hadronization models.

Vittoria Demozzi, Viatcheslav Mukhanov, Hector Rubinstein

We consider the possibility of generation of the seeds of primordial magnetic field on inflation and show that the effect of the back reaction of this field can be very important. Assuming that back reaction does not spoil inflation we find a rather strong restriction on the amplitude of the primordial seeds which could be generated on inflation. Namely, thi

R. C. Albers, N. E. Christensen, A. Svane

The last decade has seen a large increase in the number of electronic-structure calculations that involve adding a Hubbard term to the local density approximation band-structure Hamiltonian. The Hubbard term is then solved either at the mean-field level or with sophisticated many-body techniques such as dynamical mean field theory. We review the physics unde

Naoto Tsuji, Takashi Oka, Hideo Aoki

In order to investigate photoinduced insulator-metal transitions observed in correlated electron systems, we propose a new theoretical method, where we combine a Floquet-matrix method for AC-driven systems with the dynamical mean-field theory. The method can treat nonequilibrium steady states exactly beyond the linear-response regime. We have applied the met

Ricardo Almeida, Delfim F. M. Torres

We prove Euler-Lagrange fractional equations and sufficient optimality conditions for problems of the calculus of variations with functionals containing both fractional derivatives and fractional integrals in the sense of Riemann-Liouville.

M. E. Putman, J. E. G. Peek, F. Heitsch

We discuss the support for the cooling of gas directly at the disk-halo interface as a mechanism to continually fuel a galaxy. This may be an important reservoir as there is not enough cold gas observed in galaxy halos and simulations indicate the existing cold clouds will be rapidly destroyed as they move through the surrounding halo medium. We show possibl

Keiko Kawamuro

It has been conjectured that the algebraic crossing number of a link is uniquely determined in minimal braid representation. This conjecture is true for many classes of knots and links. The Morton-Franks-Williams inequality gives a lower bound for braid index. And sharpness of the inequality on a knot type implies the truth of the conjecture for the knot typ

Guido Bell, Volker Pilipp

The approximate tree decays B- -> pi- pi0/rho- rho0 may serve as benchmark channels for testing the various theoretical descriptions of the strong interaction dynamics in hadronic B meson decays. The ratios of hadronic and differential semileptonic B -> pi l nu/rho l nu decay rates at maximum recoil provide particularly clean probes of the QCD dynamics. We c

Bruin Benthem, Yuri Levin

Braginsky, Gorodetsky, and Vyatchanin have shown that thermo-refractive fluctuations are an important source of noise in interferometric gravitational-wave detectors. In particular, the thermo-refractive noise in the GEO600 beamsplitter is expected to make a substantial contribution to the interferometer's total noise budget. Here we present a new computatio

N. Armesto, L. Cunqueiro, C. A. Salgado

We present a Monte Carlo implementation, within PYTHIA, of medium-induced gluon radiation in the final state branching process. Medium effects are introduced through an additive term in the splitting functions computed in the multiple-soft scattering approximation. The observable effects of this modification are studied for different quantities as fragmentat

David M. Blei, John D. Lafferty

We describe a new method for visualizing topics, the distributions over terms that are automatically extracted from large text corpora using latent variable models. Our method finds significant $n$-grams related to a topic, which are then used to help understand and interpret the underlying distribution. Compared with the usual visualization, which simply li

M. C. Cassidy, A. S. Dzurak, R. G. Clark, K. D. Petersson

We report on charge sensing measurements of a GaAs semiconductor quantum dot device using a radio frequency quantum point contact (rf-QPC). The rf-QPC is fully characterized at 4 K and milli-Kelvin temperatures and found to have a bandwidth exceeding 20 MHz. For single-shot charge sensing we achieve a charge sensitivity of 2x10^-4 e/(sqrt)Hz referred to the

B. Chanteau, J. Fresnais, J. -F. Berret

Applications of nanoparticles in biology require that the nanoparticles remain stable in solutions containing high concentrations of proteins and salts, as well as in cell culture media. In this work, we developed simple protocols for the coating of sub-10 nm nanoparticles and evaluated the colloidal stability of dispersions in various environments. Ligands

Thomas Hambye, Michel H. G. Tytgat

We argue that the lightest vector bound states of a confining hidden sector communicating with the Standard Model through the Higgs portal are stable and are viable candidates of dark matter. The model is based on an SU(2) gauge group with a scalar field in its fundamental representation and the stability of the lightest vector bound state results from the e

Julien Cohen

Browsing is a way of finding documents in a large amount of data which is complementary to querying and which is particularly suitable for multimedia documents. Locating particular documents in a very large collection of multimedia documents such as the ones available in peer to peer networks is a difficult task. However, current peer to peer systems do not

Matthieu Josuat-Vergès

A classical result of Euler states that the tangent numbers are an alternating sum of Eulerian numbers. A dual result of Roselle states that the secant numbers can be obtained by a signed enumeration of derangements. We show that both identities can be refined with the following statistics: the number of crossings in permutations and derangements, and the nu

Sergei Nayakshin, Mark I. Wilkinson, Andrew King

It is now well established that many galaxies have nuclear star clusters (NCs) whose total masses correlate with the velocity dispersion (sigma) of the galaxy spheroid in a very similar way to the well--known supermassive black hole (SMBH) M - sigma relation. Previous theoretical work suggested that both correlations can be explained by a momentum feedback a

Dastgeer Shaikh, G. P. Zank

Observations of interstellar scintillations at radio wavelengths reveal a Kolmogorov-like scaling of the electron density spectrum with a spectral slope of -5/3 over six decades in wavenumber space. A similar turbulent density spectrum in the solar wind plasma has been reported. The energy transfer process in the magnetized solar wind plasma over such extend

Johan Öinert, Patrik Lundström

We show that if a groupoid graded ring has a certain nonzero ideal property and the principal component of the ring is commutative, then the intersection of a nonzero twosided ideal of the ring with the commutant of the principal component of the ring is nonzero. Furthermore, we show that for a skew groupoid ring with commutative principal component, the pri

Elemer E Rosinger

Essentials of sheaves are briefly presented, followed by related comments on presheaves, bundles, manifolds and singularities, aiming to point to their differences not only in their different formal mathematical structures, but also in the very purposes for which they were introduced in the first place.

Manel Errando, Elina Lindfors, Daniel Mazin, Elisa Prandini

The MAGIC telescope observed the region around the distant blazar 3C 66A for 54.2 hr in 2007 August-December. The observations resulted in the discovery of a gamma-ray source centered at celestial coordinates R.A. = 2h23m12s and decl.= 43deg 0.7arcmin (MAGIC J0223+430), coinciding with the nearby radio galaxy 3C 66B. A possible association of the excess with

Stefano Covino, Markus Garczarczyk, Markus Gaug, Angelo Antonelli

Gamma-ray bursts are cosmological sources emitting radiation from the gamma-rays to the radio band. Substantial observational efforts have been devoted to the study of GRBs during the prompt phase, i.e. the initial burst of high-energy radiation, and during the longer-lasting afterglows. In spite of many successes in interpreting these phenomena there are st

T. Jogler, N. Puchades, O. Blanch Bigas, V. Bosch-Ramon

The discovery of emission of TeV gamma rays from X-ray binaries has triggered an intense effort to better understand the particle acceleration, absorption, and emission mechanisms in compact binary systems. Here we present the pioneering effort of the MAGIC collaboration to understand the very high energy emission of the prototype system LS I +61 303. We rep

Michel Cristofol, Lionel Roques

We consider the problem of forecasting the regions at higher risk for newly introduced invasive species. Favourable and unfavourable regions may indeed not be known a priori, especially for exotic species whose hosts in native range and newly-colonised areas can be different. Assuming that the species is modelled by a logistic-like reaction-diffusion equatio

Lionel Roques, Mickaël D. Chekroun

There is a gap between single-species model predictions, and empirical studies, regarding the effect of habitat fragmentation per se, i.e., a process involving the breaking apart of habitat without loss of habitat. Empirical works indicate that fragmentation can have positive as well as negative effects, whereas, traditionally, single-species models predict

Lionel Roques, Alain Roques, Henri Berestycki, André Kretzschmar

As a result of climate change, many populations have to modify their range to follow the suitable areas - their &#34;climate envelope&#34; - often risking extinction. During this migration process, they may face absolute boundaries to dispersal, because of external environmental factors. Consequently, not only the position, but also the shape of the climate

M. F. da Silva, G. A. Lobos, V. Ramos Batista

We find the first examples of triply periodic minimal surfaces of which the intrinsic symmetries are all of horizontal type.

Brian E. Forrest, Hun Hee Lee, Ebrahim Samei

In this paper we will study the projetivity of various natural modules associated to operator Segal algebras of the Fourier algebra of a locally compact group. In particular, we will focus on the question of identifying when such modules will be projective in the category of operator spaces. Projectivity often implies that the underlying group is discrete or

Xianbo Xiao, Yuguang Chen

A scheme of spin diode is proposed that uses a step-like quantum wire with Rashba spin-orbit interaction, connected to two leads with different width. It is shown that a very large vertical spin-polarized current can be generated when electrons transmit from the narrow lead to the wide lead, however, it vanishes or becomes very weak when the transport direct

Yu. M. Bystritskiy, A. V. Guskov, V. N. Pervushin, M. K. Volkov

The charge pion polarizability is calculated in the Nambu-Jona-Lasinio model, where the quark loops (in the mean field approximation) and the meson loops (in the $1/N_c$ approximation) are taken into account. We show that quark loop contribution dominates, because the meson loops strongly conceal each other. The sigma-pole contribution $(m^2_σ-t)^{-1}$ plays

F. M. Zimmer, S. G. Magalhães, B. Coqblin

The physics of disordered alloys, such as typically the well known case of CeNi1-xCux alloys, showing an interplay among the Kondo effect, the spin glass state and a magnetic order, has been studied firstly within an average description like in the Sherrington-Kirkpatrick model. Recently, a theoretical model (PRB 74, 014427 (2006)) involving a more local des

Josep Elgueta

The regular representation of an essentially finite 2-group $\mathbb{G}$ in the 2-category $\mathbf{2Vect}_k$ of (Kapranov and Voevodsky) 2-vector spaces is defined and cohomology invariants classifying it computed. It is next shown that all hom-categories in $\mathbf{Rep}_{\mathbf{2Vect}_k}(\mathbb{G})$ are 2-vector spaces under quite standard assumptions o

T. Banks

I argue that conventional estimates of the criterion for classical behavior of a macroscopic body are incorrect in most circumstances,because they do not take into account the locality of interactions, which characterizes the behavior of all systems described approximately by local quantum field theory. The deviations from classical behavior of a macroscopic

O. Petruk, F. Bocchino, M. Miceli, G. Dubner

We propose a method to synthesize the inverse Compton (IC) gamma-ray image of a supernova remnant starting from the radio (or hard X-ray) map and using results of the spatially resolved X-ray spectral analysis. The method is successfully applied to SN 1006. We found that synthesized IC gamma-ray images of SN 1006 show morphology in nice agreement with that r

A. Arbieto, R. Markarian, M. J. Pacifico, R. Soares

Since the seminal work of Sinai one studies chaotic properties of planar billiards tables. Among them is the study of decay of correlations for these tables. There are examples in the literature of tables with exponential and even polynomial decay. However, until now nothing is known about mixing properties for billiard tables with non-compact cusps. There i

A. Cangiani

We present here a detailed description of the model of ran-driven nuclear transduction in living cells to be published elswere. The mathematical model presented is the first to account for the active transport of molecules along the cytoplasmic microtubules. All parameters entering the models are thoroughly discussed. The simulations reproduce the behavior o

Yasushi Komori, Kohji Matsumoto, Hirofumi Tsumura

In our previous work, we established the theory of multi-variable Witten zeta-functions, which are called the zeta-functions of root systems. We have already considered the cases of types $A_2$, $A_3$, $B_2$, $B_3$ and $C_3$. In this paper, we consider the case of $G_2$-type. We define certain analogues of Bernoulli polynomials of $G_2$-type and study the ge

Ignasi Reichardt, Javier Rico, Emiliano Carmona, Jose Luis Contreras

The MAGIC I telescope produces currently around 100TByte of raw data per year that is calibrated and reduced on-site at the Observatorio del Roque de los Muchachos (La Palma). Since February 2007 most of the data have been stored and further processed in the Port d&#39;Informacio Cientifica (PIC), Barcelona. This facility, which supports the GRID Tier 1 cent

Zengwei Zhu, Elena Hassinger, Zhu'an Xu, Dai Aoki

In contrast to almost all anisotropic superconductors, the upper critical field of URu$_{2}$Si$_{2}$ is larger when the field is oriented along the less conducting direction. We present a study of resistivity and Seebeck coefficient extended down to sub-Kelvin temperature range uncovering a singular case of anisotropy. When the current is injected along the

Dmitry Gourevitch

This is my PhD thesis submitted to the Weizmann Institute of Science. It is based on the papers [AG08c], [AG08d], [AGRS07], [AGS08], [AGS09], [Aiz08] and [SZ08]. This thesis includes an introduction to Gelfand pairs and invariant distributions, a list of tools to work with invariant distributions oriented towards proving Gelfand property and a proof that the

G. Marmo, G. Morandi, N. Mukunda

We review here some conventional as well as less conventional aspects of the time-independent and time-dependent Hamilton-Jacobi (HJ) theory and of its connections with Quantum Mechanics. Less conventional aspects involve the HJ theory on the tangent bundle of a configuration manifold, the quantum HJ theory, HJ problems for general differential operators and