June 2009 arXiv papers — page 23

F. V. Kyrychenko, C. A. Ullrich

The static conductivity of the dilute magnetic semiconductor GaMnAs is calculated using the memory function formalism and time-dependent density-functional theory to account for impurity scattering and to treat Hartree and exchange interactions within the hole gas. We find that the Coulomb scattering off the charged impurities alone is not sufficient to expl

R. L. Oldershaw

Discrete Scale Relativity proposes a new symmetry principle called discrete cosmological self-similarity which relates each class of systems and phenomena on a given Scale of nature's discrete cosmological hierarchy to the equivalent class of analogue systems and phenomena on any other Scale. The new symmetry principle can be understood in terms of discr

V. Rivasseau

In this pedagogical note we propose to wander through five different methods to compute the number of connected graphs of the zero-dimensional $ϕ^4$ field theory,in increasing order of sophistication. The note does not contain any new result but may be helpful to summarize the heart of constructive resummations, namely a replica trick and a forest formula.

Marcin Kaźmierczak

The minimal coupling procedure, which is employed in standard Yang-Mills theories, appears to be ambiguous in the case of gravity. We propose a slight modification of this procedure, which removes the ambiguity. Our modification justifies some earlier results concerning the consequences of the Poincaré gauge theory of gravity. In particular, the predictions

C. Almeida, C. M. Baugh, C. G. Lacey, C. S. Frenk

We introduce a new technique based on artificial neural networks which allows us to make accurate predictions for the spectral energy distributions (SEDs) of large samples of galaxies, at wavelengths ranging from the far-ultra-violet to the sub-millimetre and radio. The neural net is trained to reproduce the SEDs predicted by a hybrid code comprised of the G

Alessandra Silvestri

Viable models of modified gravity designed to produce cosmic acceleration at the current epoch, closely mimic the $Λ$CDM model at the level of background cosmology. However, this degeneracy is generically broken at the level of linear perturbations, where the modifications induce a peculiar scale-dependent pattern. A similar pattern is expected in models of

H. Wadati, D. G. Hawthorn, J. Geck, T. Z. Regier

We present an x-ray absorption study of the dependence of the V oxidation state on the thickness of LaVO$_3$ (LVO) and capping LaAlO$_3$ (LAO) layers in the multilayer structure of LVO sandwiched between LAO. We found that the change of the valence of V as a function of LAO layer thickness can be qualitatively explained by a transition between electronically

Motohiko Kusakabe, Toshitaka Kajino, Takashi Yoshida, Grant J. Mathews

It has been suggested that relic long-lived strongly interacting massive particles (SIMPs, or $X$ particles) existed in the early universe. We study effects of such long-lived unstable SIMPs on big bang nucleosynthesis (BBN) assuming that such particles existed during the BBN epoch, but then decayed long before they could be detected. The interaction strengt

Marshall W. Bautz, Eric D. Miller, Jeremy S. Sanders, Keith A. Arnaud

We report Suzaku observations of the galaxy cluster Abell 1795 that extend to r_200 ~ 2 Mpc, the radius within which the mean cluster mass density is 200 times the cosmic critical density. These observations are the first to probe the state of the intracluster medium in this object at r > 1.3 Mpc. We sample two disjoint sectors in the cluster outskirts (1.3

M. Kacprowicz, R. Demkowicz-Dobrzanski, W. Wasilewski, K. Banaszek

When standard light sources are employed, the precision of the phase determination is limited by the shot noise. Quantum entanglement provides means to exceed this limit with the celebrated example of N00N states that saturate the ultimate Heisenberg limit on precision, but at the same time are extremely fragile to losses. In contrast, we provide experimenta

Caleb Eckhardt

Let $ϕ:M_n\to B(H)$ be an injective, completely positive contraction with $\Vϕ^{-1}:ϕ(M_n)\to M_n\V_{cb}\leq1+δ(ε).$ We show that if either (i) $ϕ(M_n)$ is faithful modulo the compact operators or (ii) $ϕ(M_n)$ approximately contains a rank 1 projection, then there is a complete order embedding $ψ:M_n\to B(H)$ with $\Vϕ-ψ\V_{cb}<ε.$ We also give examples sho

A. V. Odesskii, V. V. Sokolov

We review the role of Gibbons-Tsarev-type systems in classification of integrable multi-dimensional hydrodynamic-type systems. Our main observation is an universality of Gibbons-Tsarev-type systems. We also constract explicitly a wide class of 3-dimensional hydrodynamic-type systems corresponding to the simplest possible Gibbons-Tsarev-type system.

Jérôme Margueron, Stéphane Goriely, Marcella Grasso, Gianluca Colo

We study the effect of time-odd components of the Skyrme energy density functionals on the ground state of finite nuclei and in nuclear matter. The spin-density dependent terms, which have been recently proposed as an extension of the standard Skyrme interaction, are shown to change the total binding energy of odd-nuclei by only few tenths of keV, while the

Steven A. Frank

We typically observe large-scale outcomes that arise from the interactions of many hidden, small-scale processes. Examples include age of disease onset, rates of amino acid substitutions, and composition of ecological communities. The macroscopic patterns in each problem often vary around a characteristic shape that can be generated by neutral processes. A n

Eladio Ocana Anaya, Michel De Lara, Ricardo Oliveros--Ramos, Jorge Tam

We consider sustainable management issues formulated within the framework of control theory. The problem is one of controlling a discrete--time dynamical system (e.g. population model) in the presence of state and control constraints, representing conflicting economic and ecological issues for instance. The viability kernel is known to play a basic role for

Michael Shaughnessy, C. Y. Fong, Ryan Snow, Kai Liu

Recently, the magnetic moment/Mn, $M$, in Mn$_x$Si$_{1-x}$ was measured to be 5.0 $μ_B$/Mn, at $x$ =0.1%. To understand this observed $M$, we investigate several Mn$_x$Si$_{1-x}$ models of alloys using first-principles density functional methods. The only model giving $M = 5.0$ was a 513-atom cell having the Mn at a substitutional site, and Si at a second-ne

Debashis Paul, Jie Peng, Prabir Burman

In this paper, we propose a semi-parametric model for autonomous nonlinear dynamical systems and devise an estimation procedure for model fitting. This model incorporates subject-specific effects and can be viewed as a nonlinear semi-parametric mixed effects model. We also propose a computationally efficient model selection procedure. We prove consistency of

A. Farhoodfar, X. Chen, R. J. Gooding, W. A. Atkinson

Partially-projected Gutzwiller variational wavefunctions are used to describe the ground state of disordered interacting systems of fermions. We compare several different variational ground states with the exact ground state for disordered one-dimensional chains, with the goal of determining a minimal set of variational parameters required to accurately desc

Paul J. Groot, K. Verbeek, R. Greimel, M. Irwin

The UV-Excess Survey of the Northern Galactic Plane images a 10x185 degree wide band, centered on the Galactic Equator using the 2.5m Isaac Newton Telescope in four bands (U,g,r,HeI5875) down to ~21st-22nd magnitude (~20th in HeI5875). The setup and data reduction procedures are described. Simulations of the colours of main-sequence stars, giant, supergiants

N. Peretto, G. A. Fuller

The majority of stars form in clusters. Therefore a comprehensive view of star formation requires understanding the initial conditions for cluster formation. The goal of our study is to shed light on the physical properties of infrared dark clouds (IRDCs) and the role they play in the formation of stellar clusters. This article, the first of a series dedicat

Xavier Allamigeon, Stephane Gaubert, Ricardo D. Katz

The celebrated upper bound theorem of McMullen determines the maximal number of extreme points of a polyhedron in terms of its dimension and the number of constraints which define it, showing that the maximum is attained by the polar of the cyclic polytope. We show that the same bound is valid in the tropical setting, up to a trivial modification. Then, we s

Mugurel Ionut Andreica, Madalina Ecaterina Andreica, Costel Visan

In this paper we consider multiple constrained resource allocation problems, where the constraints can be specified by formulating activity dependency restrictions or by using game-theoretic models. All the problems are focused on generic resources, with a few exceptions which consider financial resources in particular. The problems consider low-risk circums

David Andrieux, Takaaki Monnai

We derive analytical formulae for the firing rate of integrate-and-fire neurons endowed with realistic synaptic dynamics. In particular we include the possibility of multiple synaptic inputs as well as the effect of an absolute refractory period into the description.

Daniel Waltner, Klaus Richter

We illustrate how classical chaotic dynamics influences the quantum properties at mesoscopic scales. As a model case we study semiclassically coherent transport through ballistic mesoscopic systems within the Landauer formalism beyond the so-called diagonal approximation, i.e. by incorporating classical action correlations. In this context we review and expl

András Pál

Among the group of extrasolar planets, transiting planets provide a great opportunity to obtain direct measurements for the basic physical properties, such as mass and radius of these objects. These planets are therefore highly important in the understanding of the evolution and formation of planetary systems: from the observations of photometric transits, t

Mugurel Ionut Andreica, Nicolae Tapus

In this paper we consider several problems concerning packet routing in distributed systems. Each problem is formulated using terms from Graph Theory and for each problem we present efficient, novel, algorithmic techniques for computing optimal solutions. We address topics like: bottleneck paths (trees), optimal paths with non-linear costs, optimal paths wit

Julie O&#39;Donovan

We study the problem of when a Brownian motion in the unit ball has a positive probability of avoiding a countable collection of spherical obstacles. We give a necessary and sufficient integral condition for such a collection to be avoidable.

Osama Terra, Gesine Grosche, Katharina Predehl, Ronald Holzwarth

We have explored the performance of two &#34;dark fibers&#34; of a commercial telecommunication fiber link for a remote comparison of optical clocks. The two fibers, linking the Leibniz University of Hanover (LUH) with the Physi-kalisch-Technische Bundesanstalt (PTB) in Braunschweig, are connected in Hanover to form a total fiber length of 146 km. At PTB the

A. Kadeer, J. G. Korner

We provide a pedagogical introduction to the subject of Standard Model decays of unpolarized top quarks into unpolarized and polarized $W$-bosons including their QCD and electroweak radiative corrections.

J. -G. Caputo, E. Kazantseva, A. Maimistov

We consider the propagation of extremely short pulses through a dielectric thin film containing resonant atoms (two level atoms) with permanent dipole. Assuming that the film width is less than the field wave length, we can solve the wave equation and reduce the problem to a system of generalized Bloch equations describing the resonant atoms. We compute the

Yorck Sommerhaeuser, Yongchang Zhu

For a semisimple factorizable Hopf algebra over a field of characteristic zero, we show that the value that an integral takes on the inverse Drinfel&#39;d element differs from the value that it takes on the Drinfel&#39;d element itself at most by a fourth root of unity. This can be reformulated by saying that the central charge of the Hopf algebra is an inte

Francis Halzen

After a brief review of the status of the kilometer-scale neutrino observatory IceCube, we discuss the prospect that such detectors discover the still-enigmatic sources of cosmic rays. After all, this aspiration set the scale of the instrument. While only a smoking gun is missing for the case that the Galactic component of the cosmic-ray spectrum originates

Panos Giannopoulos, Christian Knauer, Gunter Rote, Daniel Werner

We study the parameterized complexity of the following fundamental geometric problems with respect to the dimension $d$: i) Given $n$ points in $\Rd$, compute their minimum enclosing cylinder. ii) Given two $n$-point sets in $\Rd$, decide whether they can be separated by two hyperplanes. iii) Given a system of $n$ linear inequalities with $d$ variables, find

Andrew N. Jordan, Alexander N. Korotkov

We review and expand on recent advances in theory and experiments concerning the problem of wavefunction uncollapse: Given an unknown state that has been disturbed by a generalized measurement, restore the state to its initial configuration. We describe how this is probabilistically possible with a subsequent measurement that involves erasing the information

Bernhard G. Bodmann, My Le, Letty Reza, Matthew Tobin

We develop the theory of frames and Parseval frames for finite-dimensional vector spaces over the binary numbers. This includes characterizations which are similar to frames and Parseval frames for real or complex Hilbert spaces, and the discussion of conceptual differences caused by the lack of a proper inner product on binary vector spaces. We also define

Mihai Halic

In an unpublished preprint, A. King conjectured that there are tilting bundles over projective varieties which are obtained as invariant quotients of affine spaces for linear actions of reductive groups. The goal of this paper is to give further examples of strong exceptional sequences of vector bundles on certain projective varieties. These are obtained as

James E. Sprittles, Yulii D. Shikhmurzaev

Numerical issues arising in computations of viscous flows in corners formed by a liquid-fluid free surface and a solid boundary are considered. It is shown that on the solid a Dirichlet boundary condition, which removes multivaluedness of velocity in the `moving contact-line problem&#39; and gives rise to a logarithmic singularity of pressure, requires a cer

Martin Drozda, Sven Schaust, Helena Szczerbicka

A sensor network is a collection of wireless devices that are able to monitor physical or environmental conditions. These devices (nodes) are expected to operate autonomously, be battery powered and have very limited computational capabilities. This makes the task of protecting a sensor network against misbehavior or possible malfunction a challenging proble

Didier Fraix-Burnet, Emmanuel Davoust, Corinne Charbonnel

We perform an evolutionary multivariate analysis of a sample of 54 Galactic globular clusters with high-quality colour-magnitude diagrams and well-determined ages. The four parameters adopted for the analysis are: metallicity, age, maximum temperature on the horizontal branch, and absolute V magnitude. Our cladistic analysis breaks the sample into three nove

Luis Alfredo Muñoz

I study variations of the standard leptogenesis scenario that can arise if an additional mass scale related to the breaking of some new symmetry is present below the mass $M_{N_1}$ of the lightest right-handed Majorana neutrino. I present a particular realization of this scheme that allows for leptogenesis at the TeV scale. In this realization the baryon asy

Cyril Demarche

Let G be a connected linear algebraic group over a number field k. We establish an exact sequence describing the closure of the group G(k) of rational points of G in the group of adelic points of G. This exact sequence describes the defect of strong approximation on G in terms of the algebraic Brauer group of G. In particular, we deduce from those results th

Jianhai Bao, Xuerong Mao, Chenggui Yuan

In this paper, we are interested in the numerical solutions of stochastic functional differential equations (SFDEs) with {\it jumps}. Under the global Lipschitz condition, we show that the $p$th moment convergence of the Euler-Maruyama (EM) numerical solutions to SFDEs with jumps has order $1/p$ for any $p\ge 2$. This is significantly different from the case

Su-Yong Lee, Jiyong Park, Se-Wan Ji, C. H. Raymond Ooi

We examine nonclassical properties of the field states generated by applying the photon annihilation-then-creation operation (AC) and creation-then-annihilation operation (CA) to the thermal and coherent states. Effects of repeated applications of AC and of CA are also studied. We also discuss experimental schemes to realize AC and CA with a cavity system us

Cyril Demarche

We consider a complex of tori of length 2 defined over a number field k. We establish here some local and global duality theorems for the (étale or Galois) hypercohomology of such a complex. We prove the existence of a Poitou-Tate exact sequence for such a complex, which generalizes the Poitou-Tate exact sequences for finite Galois modules and tori. In parti

Oleg Zaitsev, Lev Deych

We review recent extensions of semiclassical multimode laser theory to open systems with overlapping resonances and inhomogeneous refractive index. An essential ingredient of the theory are biorthogonal quasimodes that describe field decay in an open passive system and are used as a basis for lasing modes. We discuss applications of the semiclassical theory,

R. M. Nicol, S. C. Chapman, R. O. Dendy

The power spectrum of the evolving solar wind shows evidence of a spectral break between an inertial range of turbulent fluctuations at higher frequencies and a &#34;$1/f$&#34; like region at lower frequencies. In the ecliptic plane at $\sim 1$ AU, this break occurs approximately at timescales of a few hours, and is observed in the power spectra of component

A. Möller, M. Schmitt, W. Schnelle, T. Förster

We present a joint experimental and computational study of the recently synthesized spin 1/2 system silver-copper-orthovanadate AgCuVO4 [A. Möller and J. Jainski, Z. Anorg. Allg. Chem. 634, 1669 (2008)] exhibiting chains of trans corner-sharing [CuO4] plaquettes. The static magnetic susceptibility and specific heat measurements of AgCuVO4 can be described to

Alexander Yu. Cherny, Joachim Brand

Recently, Imambekov and Glazman [Phys. Rev. Lett. 100, 206805 (2008)] showed that the dynamic structure factor (DSF) of the 1D Bose gas demonstrates power-law behaviour along the limiting dispersion curve of the collective modes and calculated the corresponding exponents exactly. Combining these recent results with a previously obtained strong-coupling expan

Jean-Christophe Aval, Philippe Duchon

The aim of this work is to enumerate alternating sign matrices (ASM) that are quasi-invariant under a quarter-turn. The enumeration formula (conjectured by Duchon) involves, as a product of three terms, the number of unrestricted ASM&#39;s and the number of half-turn symmetric ASM&#39;s.

S. M. Soskin, R. Mannella, O. M. Yevtushenko, I. A. Khovanov

We consider time-periodically perturbed 1D Hamiltonian systems possessing one or more separatrices. If the perturbation is weak, then the separatrix chaos is most developed when the perturbation frequency lies in the logarithmically small or moderate ranges: this corresponds to the involvement of resonance dynamics into the separatrix chaos. We develop a met

M. R. Soltani, S. Mahdavifar, Alireza Akbari, A. A. Masoudi

We study the 1D ferromagnetic Ising (spin-1/2) model with the Dzyaloshinskii-Moriya (DM) interaction. We analyze the low energy excitation spectrum and the ground state magnetic phase diagram using the Lanczos method. The DM interaction-dependency is calculated for the low-energy excitation spectrum, spiral order parameter and spin-spin correlation functions

M. Amouch, H. Zguitti

Let $X$ a Banach space and $T$ a bounded linear operator on $X.$ We denote by $S(T)$ the set of all $λ\in \cit$ such that $T$ does not have the single-valued extension property at $λ$. In this note we prove equality up to $S(T)$ between the left Drazin spectrum and the left B-Fredholm spectrum and between the semi-essential approximate point spectrum and the

A. Feito, J. S. Lundeen, H. Coldenstrodt-Ronge, J. Eisert

Recent efforts have applied quantum tomography techniques to the calibration and characterization of complex quantum detectors using minimal assumptions. In this work we provide detail and insight concerning the formalism, the experimental and theoretical challenges and the scope of these tomographical tools. Our focus is on the detection of photons with ava

Jens Geissler, Bernd Hofmann

This paper addresses Tikhonov like regularization methods with convex penalty functionals for solving nonlinear ill-posed operator equations formulated in Banach or, more general, topological spaces. We present an approach for proving convergence rates which combines advantages of approximate source conditions and variational inequalities. Precisely, our tec

B. Rossi, I. Badhress, A. Ereditato, S. Haug

This paper describes the design, realization and operation of a prototype liquid Argon Time Projection Chamber (LAr TPC) detector dedicated to the development of a novel online monitoring and calibration system exploiting UV laser beams. In particular, the system is intended to measure the lifetime of the primary ionization in LAr, in turn related to the LAr

G. Dissertori, A. Gehrmann-De Ridder, T. Gehrmann, E. W. N. Glover

We present a determination of the strong coupling constant from a fit of QCD predictions for six event-shape variables, calculated at next-to-next-to-leading order (NNLO) and matched to resummation in the next-to-leading-logarithmic approximation (NLLA). These event shapes have been measured in e+e- annihilations at LEP, where the data we use have been colle

Thierry Coquand, Erik Palmgren, Bas Spitters

We show that the set of points of an overt closed subspace of a metric completion of a Bishop-locally compact metric space is located. Consequently, if the subspace is, moreover, compact, then its collection of points is Bishop compact.

Michele Cantiello, Enzo Brocato, John P. Blakeslee

Aims.We study the photometric and structural properties of the star cluster system in the late type Sc spiral NGC 3370. Methods. BVI observations from the Advanced Camera for Surveys on board of HST are used to analyse in detail the colours, magnitudes and spatial properties of cluster candidates. The final catalogue of sources used for the study is composed

Prakash Sarkar, Jaswant Yadav, Biswajit Pandey, Somnath Bharadwaj

The assumption that the Universe, on sufficiently large scales, is homogeneous and isotropic is crucial to our current understanding of cosmology. In this paper we test if the observed galaxy distribution is actually homogeneous on large scales. We have carried out a multifractal analysis of the galaxy distribution in a volume limited subsample from the SDSS

M. Coraddu, M. Lissia, P. Quarati, A. M. Scarfone

Experimental measurements in terrestrial laboratory, space and astrophysical observations of variation and fluctuation of nuclear decay constants, measurements of large enhancements in fusion reaction rate of deuterons implanted in metals and electron capture by nuclei in solar core indicate that these processes depend on the environment where take place and

M. K. Abubekerov, E. A. Antokhina, A. I. Bogomazov, A. M. Cherepashchuk

We have analyzed the observed radial-velocity curve for the X-ray binary M33 X-7 in a Roche model. We have analyzed the dependence between the component masses and the degree of filling of the optical star&#39;s Roche lobe to obtain the ratio of the masses of the optical star and compact object. For the most probable mass of the optical star, $m_v=70M_{\odot

William Y. C. Chen, Christian M. Reidys

We study two variations of the Brauer algebra $B_n(x)$. The first is the algebra $A_n(x)$, which generalizes the Brauer algebra by considering loops. The second is the algebra $L_n(x)$, the $A_n(x)$-subalgebra generated by diagrams without horizontal arcs. $A_n(x)$ and $L_n(x)$ have for $x \neq 0$ an hereditary-chain indexed by all integers. Following the id

F. Kaiser, V. Jacques, A. Batalov, P. Siyushev

In this report, the polarization properties of the photoluminescence emitted by single nitrogen-vacancy (NV) color centers in diamond are investigated using resonant excitation at cryogenic temperature. We first underline that the two excited-state orbital branches are associated with two orthogonal transition dipoles. Using selective excitation of one dipol

Laetitia Andrieu, Michel De Lara, Babacar Seck

We provide an economic interpretation of the practice consisting in incorporating risk measures as constraints in a classic expected return maximization problem. For what we call the infimum of expectations class of risk measures, we show that if the decision maker (DM) maximizes the expectation of a random return under constraint that the risk measure is bo

Ziyuan Wang, Lars Kulik, Kotagiri Ramamohanarao

Traffic Congestions and accidents are major concerns in today&#39;s transportation systems. This thesis investigates how to optimize traffic flow on highways, in particular for merging situations such as intersections where a ramp leads onto the highway. In our work, cars are equipped with sensors that can detect distance to neighboring cars, and communicate

Atzmon Hen-Tov, David H. Lorenz, Lior Schachter

Developing and maintaining complex, large-scale, product line of highly customized software systems is difficult and costly. Part of the difficulty is due to the need to communicate business knowledge between domain experts and application programmers. Domain specific model driven development (MDD) addresses this difficulty by providing domain experts and de

Sz. Mészáros, E. H. Avrett, A. K. Dupree

Chromospheric model calculations of the Halpha line for selected red giant branch (RGB) and asymptotic giant branch (AGB) stars in the globular clusters M13, M15, and M92 are constructed to derive mass loss rates. The model spectra are compared to the observations obtained with the Hectochelle on the MMT telescope. These stars show strong Halpha emissions an

Deepak Parashar, Bruce W. Westbury

We calculate a two-parameter R-matrix which specialises to the trigonometric R-matrix of the minimal affinisation of the adjoint representation of each of the classical simple Lie algebras so(n) and sp(n).

Borge ten Hagen, Sven van Teeffelen, Hartmut Löwen

The overdamped Brownian motion of a self-propelled particle which is driven by a projected internal force is studied by solving the Langevin equation analytically. The &#34;active&#34; particle under study is restricted to move along a linear channel. The direction of its internal force is orientationally diffusing on a unit circle in a plane perpendicular t

Stefano Galatolo

We prove that if a system has superpolynomial (faster than any power law) decay of correlations (with respect to Lipschitz observables) then the time $τ(x,S_{r})$ needed for a typical point $x$ to enter for the first time a set $S_{r}=\{x:f(x)\leq r\}$ which is a sublevel of a Lipschitz funcion $f$ scales as $\frac{1}{μ(S_{r})}$ i.e. \begin{equation*} \under

Hua-Lin Huang, Gongxiang Liu, Yu Ye

We study finite quasi-quantum groups in their quiver setting developed recently by the first author in arXiv:0902.1620 and arXiv:0903.1472. We obtain a classification of finite-dimensional pointed Majid algebras of finite corepresentation type, or equivalently a classification of elementary quasi-Hopf algebras of finite representation type, over the field of

A. M. S. Smith, L. Hebb, A. Collier Cameron, D. R. Anderson

We present results from a search for additional transiting planets in 24 systems already known to contain a transiting planet. We model the transits due to the known planet in each system and subtract these models from lightcurves obtained with the SuperWASP survey instruments. These residual lightcurves are then searched for evidence of additional periodic

Ma. Louise Antonette N. De Las Penas, Ma. Carlota B. Decena, Glenn R. Laigo

In this work, we derive the low index subgroups of the extended Hecke, Hecke and the Picard groups using tools in color symmetry theory. We also present the low index subgroups of the modular group.

J. L. Skilton, M. Pandey-Pommier, J. A. Hinton, C. C. Cheung

The few known gamma-ray binary systems are all associated with variable radio and X-ray emission. The TeV source HESS J0632+057, apparently associated with the Be star MWC148, is plausibly a new member of this class. Following the identification of a variable X-ray counterpart to the TeV source we conducted GMRT and VLA observations in June-September 2008 to

Christian Spagnol, Marta Rossi, Massimiliano Sala

We study a class of quasi-cyclic LDPC codes. We provide precise conditions guaranteeing high girth in their Tanner graph. Experimentally, the codes we propose perform no worse than random LDPC codes with their same parameters, which is a significant achievement for algebraic codes.

Ma. Louise N. De Las Penas, Rene P. Felix, Glenn R. Laigo

We present a framework to determine subgroups of tetrahedron groups and tetrahedron Kleinian groups, based on tools in color symmetry theory.

Marc Troyanov

Dans les années 1940-1970, Alexandrov et l&#39;&#34;École de Leningrad&#34; ont développé une théorie très riche des surfaces singulières. Il s&#39;agit de surfaces topologiques, munie d&#39;une métrique intrinsèque pour laquelle on peut définir une notion de courbure, qui est une mesure de Radon. Cette classe de surfaces a de bonnes propriétés de convergenc

Dan Mao, Katie Mussack, Werner Däppen

In the hot, dense plasma of solar and stellar interiors, Coulomb potentials are screened, resulting in increased nuclear reaction rates. Although Salpeter&#39;s approximation for static screening is widely accepted and used in stellar modeling, the question of screening in nuclear reactions has been revisited. In particular the issue of dynamic effects has b

Matan Karklinsky, Dan Romik

Zeilberger proved the Refined Alternating Sign Matrix Theorem, which gives a product formula, first conjectured by Mills, Robbins and Rumsey, for the number of alternating sign matrices with given top row. Stroganov proved an explicit formula for the number of alternating sign matrices with given top and bottom rows. Fischer and Romik considered a different

Hamid Reza Noori

The problem of the transformation of microscopic information to the macroscopic level is an intriguing challenge in computational neuroscience, but also of general mathematical importance. Here, a phenomenological mathematical model is introduced that simulates the internal information processing of brain compartments. Synaptic potentials are integrated over

Johan Hansson, Jesper Lindkvist

When taking the real, inhomogeneous and anisotropic matter distribution in the semi-local universe into account, there may be no need to postulate an accelerating expansion of the universe despite recent type Ia supernova data. Local curvatures must be integrated (over all space) to obtain the global curvature of the universe, which seems to be very close to

Kohei Kamada, J. Yokoyama

We study the fine-tuning problem on the initial condition of inflation in the minimal supersymmetric standard model (MSSM), associated with the narrowness of the slow-roll region. We consider two cases before the onset of the MSSM inflation, namely, the radiation dominated era and preceding inflationary era. We find thermal dissipation does not induce additi

C. J. Wareing, R. Hollerbach

Decaying electron magnetohydrodynamic (EMHD) turbulence in three dimensions is studied via high-resolution numerical simulations. The resulting energy spectra asymptotically approach a k^{-2} law with increasing R_B, the ratio of the nonlinear to linear timescales in the governing equation, consistent with theoretical predictions. No evidence is found of a d

E. Spitoni, F. Matteucci, S. Recchi, G. Cescutti

The majority of galactic chemical evolution models assumes the instantaneous mixing approximation (IMA). This assumption is probably not realistic as indicated by the existence of chemical inhomogeneities, although current chemical evolution models of the Milky Way can reproduce the majority of the observational constraints under the IMA. The aim of this pap

B. G. Konopelchenko, G. Ortenzi

Coisotropic deformations of algebraic varieties are defined as those for which an ideal of the deformed variety is a Poisson ideal. It is shown that coisotropic deformations of sets of intersection points of plane quadrics, cubics and space algebraic curves are governed, in particular, by the dKP, WDVV, dVN, d2DTL equations and other integrable hydrodynamica

M. A. Rodriguez, P. Tempesta, P. Winternitz

We construct complete sets of invariant quantities that are integrals of motion for two Hamiltonian systems obtained through a reduction procedure, thus proving that these systems are maximally superintegrable. We also discuss the reduction method used in this article and its possible generalization to other maximally superintegrable systems.

Christian Miebach, Karl Oeljeklaus

In this paper we investigate proper $\mbb{R}$--actions on hyperbolic Stein surfaces and prove in particular the following result: Let $D\subset\mbb{C}^2$ be a simply-connected bounded domain of holomorphy which admits a proper $\mbb{R}$--action by holomorphic transformations. The quotient $D/\mbb{Z}$ with respect to the induced proper $\mbb{Z}$--action is a

Maziar Nekovee

Cognitive radio is being intensively researched for opportunistic access to the so-called TV White Spaces (TVWS): large portions of the VHF/UHF TV bands which become available on a geographical basis after the digital switchover. Using accurate digital TV (DTV) coverage maps together with a database of DTV transmitters, we develop a methodology for identifyi

David Hochberg

The nonequilibrium effective potential is computed for the Frank model of spontaneous mirror symmetry breaking (SMSB) in chemistry in which external noise is introduced to account for random environmental effects. When these fluctuations exceed a critical magnitude, mirror symmetry is restored. The competition between ambient noise and the chiral bias due to

Renaud Lambiotte, Juan Carlos Gonzalez-Avella

We present a generic threshold model for the co-evolution of the structure of a network and the state of its nodes. We focus on regular directed networks and derive equations for the evolution of the system toward its absorbing state. It is shown that the system displays a transition from a connected phase to a fragmented phase that depends on its initial co

Kazuo Fujikawa

A general separability condition on the second moment (covariance matrix) for continuous variable two-party systems is derived by an analysis analogous to the derivation of the Kennard&#39;s uncertainty relation without referring to the non-negativity of the partially transposed density matrix. This separability criterion is generally more stringent than tha

A. Mazumdar, A. Merand, P. Demarque, P. Kervella

The GIII red giant star epsilon Oph has been found to exhibit several modes of oscillation by the MOST mission. We interpret the observed frequencies of oscillation in terms of theoretical radial p-mode frequencies of stellar models. Evolutionary models of this star, in both shell H-burning and core He-burning phases of evolution, are constructed using as co

Maria Simonetta Bernabei, Horst Thaler

An averaged generating function for coloured hard-dimers is being investigated by proving estimates for the latter. Furthermore, two different enumerating problems and their distributions are studied numerically.

Jacob Sterbenz, Daniel Tataru

In this article we consider large data Wave-Maps from $\mathbb{R}^{2+1}$ into a compact Riemannian manifold $(\mathcal{M},g)$, and we prove that regularity and dispersive bounds persist as long as a certain type of bulk (non-dispersive) concentration is absent. In a companion article we use these results in order to establish a full regularity theory for lar

Georg Feulner

Despite tremendous interest in the topic and decades of research, the origins of the major losses of biodiversity in the history of life on Earth remain elusive. A variety of possible causes for these mass-extinction events have been investigated, including impacts of asteroids or comets, large-scale volcanic eruptions, effects from changes in the distributi

Antonino Sergi

The ratio $R_K=\frac{Γ(K\to e ν_{e} (γ))}{Γ(K\to μν_μ (γ))}$ of leptonic decay rates provides a golden probe for testing the structure of the weak interactions because it can be predicted with high accuracy within the Standard Model. The aim of the NA62 experimental programme based on the 2007 data set is a measurement of $R_K$ reaching a new accuracy level

Françoise Damay, Christine Martin, Vincent Hardy, Antoine Maignan

The crystal and magnetic structures of the S = 3/2 chain antiferromagnet beta-CaCr2O4 have been investigated by means of specific heat, magnetization, muon relaxation and neutron powder diffraction between 300K and 1.5K. Owing to the original topology of the Cr3+ magnetic lattice, which can be described as a network of triangular ladders, equivalent to chain

Bernd Schulze

In this paper, we give a complete self-contained proof that the rigidity matrix of a symmetric bar and joint framework (as well as its transpose) can be transformed into a block-diagonalized form using techniques from group representation theory. This theorem is basic to a number of useful and interesting results concerning the rigidity and flexibility of sy

Zhaoyu Chen, Minfeng Gu, Zhonghui Fan, Xinwu Cao

We have collected all available spectra and photometric data from SDSS catalogue for bright AGNs complied from the first three months of the Fermi large area telescope all-sky survey. Based on the 106 high-confidence and 11 low-confidence association bright AGN list, the photometry data are collected from SDSS DR7 for 28 sources (12 BL Lacs and 16 FSRQs), tw

M. J. H. Luttikhof, A. G. Khachatryan, F. A. van Goor, K. -J. Boller

In recent experiments ultra-relativistic femtosecond electron bunches were generated by a Laser Wakefield Accelerator (LWFA) in different regimes. Here we predict that even attosecond bunches can be generated by an LWFA due to the fast betatron phase mixing within a femtosecond electron bunch. The attosecond bunches are stable outside the LWFA and can propag