June 2009 arXiv papers — page 25
Showing 2,401–2,500 of 5,471 papers
$σ$-Set Theory: Introduction to the concepts of $σ$-antielement, $σ$-antiset and Integer Space
math.LOIvan Gatica Araus
In this paper we develop a theory called $σ$-Set Theory, in which we present an axiom system developed from the study of Set Theories of Zermelo-Fraenkel, Neumann-Bernays-Godel and Morse-Kelley. In $σ$-Set Theory, we present the proper existence of objects called $σ$-antielement, $σ$-antiset, natural numbers, antinatural numbers and generated $σ$-set by two
Johan Bijnens, Ilaria Jemos
We report on a search of relations valid at order $p^6$ in Chiral Perturbation Theory. We have found relations between $ππ$, $πK$ scattering, $K_{\ell4}$ decays, masses and decay constants and scalar and vector form factors. In this paper we give the relations and a first numerical check of them.
E. Paladino, A. Mastellone, A. D'Arrigo, G. Falci
We present a general route to reduce inhomogeneous broadening in nanodevices due to 1/f noise. We apply this method to a universal two-qubit gate and demonstrate that for selected optimal couplings, a high-efficient gate can be implemented even in the presence of 1/f noise. Entanglement degradation due to interplay of 1/f and quantum noise is quantified via
Michael Gabler, Ulrich Sperhake, Nils Andersson
The effects of nonlinear oscillations in compact stars are attracting considerable current interest. In order to study such phenomena in the framework of fully nonlinear general relativity, highly accurate numerical studies are required. We present a numerical scheme specifically tailored for studies, based on formulating the time evolution in terms of devia
Is the misalignment of the Local Group velocity and the 2MASS Redshift Survey dipole typical in a LambdaCDM model?
astro-ph.COPirin Erdogdu, Ofer Lahav
We predict the acceleration of the Local Group generated by the 2MASS Redshift Survey within the framework of LambdaCDM and the halo model of galaxies. We show that as the galaxy fluctuations derived from the halo model have more power on small scales compared with the mass fluctuations, the misalignment angle between the CMB velocity vector and the 2MRS dip
Amalendu Krishna
For a smooth quasi-projective scheme $X$ over a field $k$ with an action of a reductive group, we establish a spectral sequence connecting the equivariant and the ordinary higher Chow groups of $X$. For $X$ smooth and projective, we show that this spectral sequence degenerates, leading to an explicit relation between the equivariant and the ordinary higher C
Selman Akbulut
Starting with the Dolgachev surface E(1)_{2,3} we construct an infinite family of distinct exotic copies of the rational surface E(1), each of which admits a handlebody decomposition without 1- and 3- handles, and we draw these handlebodies.
The long-wavelength emission of interstellar PAHs: characterizing the spinning dust contribution
astro-ph.GANathalie Ysard, Laurent Verstraete
The emission of cold dust grains at long wavelengths will soon be observed by the Planck and Herschel satellites and provide new constraints on the nature of interstellar dust. The microwave anomalous emission, proposed to be due to spinning PAHs, should help to better define these species. Moreover, understanding the fluctuations of the anomalous emission o
Fabien Buisseret, Vincent Mathieu, Claude Semay
The relativistic flux tube model is an effective description of confined quarks and gluons in which the confining interaction is carried by the flux tube, a Nambu-Goto string. We first show that the relativistic flux tube model can be applied to glueballs seen as bound states of transverse constituent gluons. After a comparison of that approach with usual sp
Patrick O. Perry, Patrick J. Wolfe
Rank estimation is a classical model order selection problem that arises in a variety of important statistical signal and array processing systems, yet is addressed relatively infrequently in the extant literature. Here we present sample covariance asymptotics stemming from random matrix theory, and bring them to bear on the problem of optimal rank estimatio
J. A. Bergstra, C. A. Middelburg
This paper concerns instruction sequences that contain probabilistic instructions, i.e. instructions that are themselves probabilistic by nature. We propose several kinds of probabilistic instructions, provide an informal operational meaning for each of them, and discuss related work. On purpose, we refrain from providing an ad hoc formal meaning for the pro
S. Sridhar, Kandaswamy Subramanian
We study large-scale dynamo action due to turbulence in the presence of a linear shear flow. Our treatment is quasilinear and equivalent to the standard `first order smoothing approximation'. However it is non perturbative in the shear strength. We first derive an integro-differential equation for the evolution of the mean magnetic field, by systematic use o
A Quasi-Periodic Oscillation of ~ 30 Minutes in the X-ray Light Curve of the BL Lac S5 0716+714
astro-ph.COAlok C. Gupta, Paul J. Wiita, Jeewan C. Pandey, A. K. Srivastava
We withdraw our claim that a component in an XMM-Newton satellite light curve of the BL Lacertae object S5 0716 + 714 shows quasi-periodic oscillations (QPOs) of $\sim$30 minutes. Although both our original periodogram and wavelet analyses gave consistent results, the data do not lead to a statistically significant result once red-noise at low frequencies is
Yaozhong Hu, David Nualart, Jian Song
We establish a version of the Feynman-Kac formula for the multidimensional stochastic heat equation with a multiplicative fractional Brownian sheet. We use the techniques of Malliavin calculus to prove that the process defined by the Feynman-Kac formula is a weak solution of the stochastic heat equation. From the Feynman-Kac formula, we establish the smoothn
Global regularity for a logarithmically supercritical hyperdissipative Navier-Stokes equation
math.APTerence Tao
Let $d \geq 3$. We consider the global Cauchy problem for the generalised Navier-Stokes system \partial_t u + (u \cdot \nabla) u &= - D^2 u - \nabla p \nabla \cdot u &= 0 u(0,x) &= u_0(x) for $u: \R^+ \times \R^d \to \R^d$ and $p: \R^+ \times \R^d \to \R$, where $u_0: \R^d \to \R^d$ is smooth and divergence free, and $D$ is a Fourier multiplier whose symbol
Claude Cibils, Maria Julia Redondo, Andrea Solotar
The main purpose of this paper is to provide explicit computations of the fundamental group of several algebras. For this purpose, given a $k$-algebra $A$, we consider the category of all connected gradings of $A$ by a group $G$ and we study the relation between gradings and Galois coverings. This theoretical tool gives information about the fundamental grou
Seokcheon Lee
We investigate the exact analytic solutions for the growths of the dark matter and the baryon in sub-horizon scale. The growth of the dark matter $δ_{\DM}$ is related to that of the halos. Thus, the exact solution for the growth of the dark matter is important to obtain the proper properties of dark matter halos. However, the dark energy model dependence of
Tianshu Luo, Yimu Guo
In this paper an approach is proposed to represent a class of dissipative mechanical systems by corresponding infinite-dimensional Hamiltonian systems. This approach is based upon the following structure: for any non-conservative classical mechanical system and arbitrary initial conditions, there exists a conservative system; both systems share one and only
Model for twin electromagnons and magnetically induced oscillatory polarization in multiferroic RMnO$_3$
cond-mat.str-elMarkku P. V. Stenberg, Rogerio de Sousa
We propose a model for the pair of electromagnon excitations observed in the class of multiferroic materials {\it R}MnO$_3$ ({\it R} is a rare-earth ion). The model is based on a harmonic cycloid ground state interacting with a zone-edge magnon and its twin excitation separated in momentum space by two times the cycloid wave vector. The pair of electromagnon
S. J. Seltzer, M. V. Romalis
Antirelaxation surface coatings allow long spin relaxation times in alkali-metal cells without buffer gas, enabling faster diffusion of the alkali atoms throughout the cell and giving larger signals due to narrower optical linewidths. Effective coatings were previously unavailable for operation at temperatures above 80 C. We demonstrate that octadecyltrichlo
P. M. Chesler, A. Gynther, A. Vuorinen
We study thermal corrections to the dispersion relations of massive fundamental particles immersed in weakly coupled non-Abelian plasmas. The cases covered include quarks in the QCD (quark-gluon) plasma, as well as N=2 quarks and scalars in an N=4 Super Yang-Mills plasma. We perform the calculations to leading order in a weak coupling expansion, and consider
Marcelo Botta Cantcheff
We study the entanglement of closed strings degrees of freedom in order to investigate the microscopic structure and statistics of objects as D-branes. By considering the macroscopic pure state (MPS) limit, whenever the entanglement entropy goes to zero (in such a way that the macroscopic properties of the state are preserved), we show that boundary states m
Andriy Myronenko, Xubo Song
We introduce an adaptive regularization approach. In contrast to conventional Tikhonov regularization, which specifies a fixed regularization operator, we estimate it simultaneously with parameters. From a Bayesian perspective we estimate the prior distribution on parameters assuming that it is close to some given model distribution. We constrain the prior d
The SAURON Project - XIV. No escape from V$_{\mathrm{esc}}$: a global and local parameter in early-type galaxy evolution
astro-ph.GANicholas Scott, Michele Cappellari, Roger L. Davies, R. Bacon
We present the results of an investigation of the local escape velocity (Vesc) - line strength index relationship for 48 early type galaxies from the SAURON sample, the first such study based on a large sample of galaxies with both detailed integral field observations and extensive dynamical modelling. Values of Vesc are computed using Multi Gaussian Expansi
C A Holmes, G J Milburn
We describe an opto-mechanical system in which the coupling between optical and mechanical degrees of freedom takes the form of a fully quantised third-order parametric interaction. Two physical realisations are proposed: a harmonically trapped atom in a standing wave and the `membrane in the middle' model. The dominant resonant interaction corresponds t
R. Navarro, R. Carretero-Gonzalez, P. G. Kevrekidis
We study the interactions between two atomic species in a binary Bose-Einstein condensate to revisit the conditions for miscibility, oscillatory dynamics between the species, steady state solutions and their stability. By employing a variational approach for a quasi one-dimensional, two-atomic species, condensate we obtain equations of motion for the paramet
L. L. Samojeden, G. M. Kremer, F. P. Devecchi
In this work we analyze the effects produced by bosonic and fermionic constituents, including quantum corrections, in two-dimensional (2D) cosmological models. We focus on a gravitational theory related to the Callan-Giddings-Harvey-Strominger model, to simulate the dynamics of a young, spatially-lineal, universe. The cosmic substratum is formed by an {\it i
Radial thresholding to mitigate Laser-Guide-Star aberrations on Centre-of-Gravity-based Shack-Hartmann wavefront sensors
astro-ph.IMOlivier Lardiere, Rodolphe Conan, Colin Bradley, Kate Jackson
Sodium Laser Guide Stars (LGSs) are elongated sources due to the thickness and the finite distance of the sodium layer. The fluctuations of the sodium layer altitude and atom density profile induce errors on centroid measurements of elongated spots, and generate spurious optical aberrations in closed--loop adaptive optics (AO) systems. According to an analyt
Salvador Barraza-Lopez, Peter M. Albrecht, Joseph W. Lyding
We present a study on the mechanical configuration and the electronic properties of semiconducting carbon nanotubes supported by partially depassivated silicon substrates, as inferred from topographic and spectroscopic data acquired with a room-temperature ultrahigh vacuum scanning tunneling microscope and density-functional theory calculations. A mechanical
Toru Okuda, Galina V. Lipunova, Diego Molteni
We examine the jets and the disc of SS 433 at super-Eddington luminosities with 600 times Eddington critical accretion rate by time-dependent two-dimensional radiation hydrodynamical calculations, assuming alpha-model for the viscosity. One-dimensional supercritical accretion disc models with mass loss or advection are used as the initial configurations of t
B. Sibthorpe, P. Chanial, M. Griffin
Instrument simulators are becoming ever more useful for planning and analysing large astronomy survey data. In this paper we present a simulator for the Herschel-SPIRE photometer. We describe the models it uses and the form of the input and output data. The SPIRE photometer simulator is a software package which uses theoretical models, along with flight mode
Matthew J. Patitz, Scott M. Summers
We review some recent results related to the self-assembly of infinite structures in the Tile Assembly Model. These results include impossibility results, as well as novel tile assembly systems in which shapes and patterns that represent various notions of computation self-assemble. Several open questions are also presented and motivated.
B. Shklyar
The exact controllability to the origin for linear evolution control equation is considered.The problem is investigated by its transformation to infinite linear moment problem. Conditions for the existence of solution for infinite linear moment problem has been obtained. The obtained results are applied to the zero controllability for control evolution equat
Rafael López
In this paper we review some author's results about Weingarten surfaces in Euclidean space $\r^3$ and hyperbolic space $\h^3$. We stress here in the search of examples of linear Weingarten surfaces that satisfy a certain geometric property. First, we consider Weingarten surfaces in $\r^3$ that are foliated by circles, proving that the surface is rotation
Zheng Gan, Helge Krueger
We construct examples, that log Hölder continuity of the integrated density of states cannot be improved. Our examples are limit-periodic.
Rafael López
It is known that planar disks and small spherical caps are the only constant mean curvature graphs whose boundary is a round circle. Usually, the proof invokes the Maximum Principle for elliptic equations. This paper presents a new proof of this result motivated by an article due to Reilly. Our proof utilizes a flux formula for surfaces with constant mean cu
Jeffrey A. Rich, Ann Merchant Boesgaard
The abundance of beryllium in the oldest, most metal-poor stars acts as a probe of early star formation and Galactic chemical evolution. We have analyzed high-resolution, high signal-to-noise Keck/HIRES spectra of 24 stars with [Fe/H] from -2.3 to -3.5 in order to determine the history of Be abundances and explore the possibility of a Be plateau. We have det
Andrey V. Kravtsov
A decade ago cosmological simulations of increasingly higher resolution were used to demonstrate that virialized regions of Cold Dark Matter (CDM) halos are filled with a multitude of dense, gravitationally-bound clumps. These dark matter subhalos are central regions of halos that survived strong gravitational tidal forces and dynamical friction during the h
Robert Roloff, Walter Pötz
A process tomography based optimization scheme for open quantum systems is used to determine the performance limits of Josephson charge qubits within current experimental means. The qubit is modeled microscopically as an open quantum system taking into account state leakage, as well as environment-induced dephasing based on experimental noise spectra. Within
Probing the IGM-Galaxy Connection at z < 0.5 I: A Galaxy Survey in QSO Fields and a Galaxy-Absorber Cross-Correlation Study
astro-ph.COHsiao-Wen Chen, John S. Mulchaey
(Abridged) We present an imaging and spectroscopic survey of galaxies in fields around QSOs HE0226-4110, PKS0405-123, and PG1216+069. The fields are selected to have ultraviolet echelle spectra available, which uncover 195 Lya absorbers and 13 OVI absorbers along the three sightlines. We obtain robust redshifts for 1104 galaxies of rest-frame absolute magnit
Heidi Jo Newberg, Brian Yanny, Benjamin A. Willett
We show that there is a low metallicity tidal stream that runs along l=143 deg. in the South Galactic Cap, about 34 kpc from the Sun, discovered from SEGUE stellar velocities. Since the most concentrated detections are in the Cetus constellation, and the orbital path is nearly polar, we name it the Cetus Polar Stream (CPS). Although it is spatially coinciden
Rafael F. Lang, Wolfgang Seidel
The search for direct interactions of dark matter particles remains one of the most pressing challenges of contemporary experimental physics. A variety of different approaches is required to probe the available parameter space and to meet the technological challenges. Here, we review the experimental efforts towards the detection of direct dark matter intera
The Star Formation Histories of Red-Sequence Galaxies, Mass-to-Light Ratios and the Fundamental Plane
astro-ph.COSteven P. Allanson, Michael J. Hudson, Russell J. Smith, John R. Lucey
This paper addresses the challenge of understanding the typical star formation histories of red sequence galaxies, using linestrength indices and mass-to-light ratios as complementary constraints on their stellar age distribution. We construct simple parametric models of the star formation history that bracket a range of scenarios, and fit these models to th
The Pagoda Sequence: a Ramble through Linear Complexity, Number Walls, D0L Sequences, Finite State Automata, and Aperiodic Tilings
cs.DMFred Lunnon
We review the concept of the number wall as an alternative to the traditional linear complexity profile (LCP), and sketch the relationship to other topics such as linear feedback shift-register (LFSR) and context-free Lindenmayer (D0L) sequences. A remarkable ternary analogue of the Thue-Morse sequence is introduced having deficiency 2 modulo 3, and this pro
Eric Goles, Pierre-Etienne Meunier, Ivan Rapaport, Guillaume Theyssier
The goal of this paper is to show why the framework of communication complexity seems suitable for the study of cellular automata. Researchers have tackled different algorithmic problems ranging from the complexity of predicting to the decidability of different dynamical properties of cellular automata. But the difference here is that we look for communicati
Ai-Hua Fan, Lingmin Liao, Ji-Hua Ma
We consider sets of real numbers in $[0,1)$ with prescribed frequencies of partial quotients in their regular continued fraction expansions. It is shown that the Hausdorff dimensions of these sets, always bounded from below by $1/2$, are given by a modified variational principle.
A. Gomez-Marin, J. M. Sancho
Here we study a pumping device capable of maintaining a density gradient and a flux of particles across a membrane. Its driving mechanism is based on the flashing ratchet effect powered by the random telegraph process in the presence of thermal fluctuations. Unlike Brownian motors, the concentrations at both reservoir boundaries need to be implemented as bou
Fiber Structure and Local Coordinates for the Teichmueller Space of a Bordered Riemann Surface
math.CVDavid Radnell, Eric Schippers
We show that the infinite-dimensional Teichmueller space of a Riemann surface whose boundary consists of n closed curves is a holomorphic fiber space over the Teichmueller space of n-punctured surfaces. Each fiber is a complex Banach manifold modeled on a two-dimensional extension of the universal Teichmueller space. The local model of the fiber, together wi
M. Daniel, W. J. de Wit, D. Dravins, D. Kieda
The imminent availability of large arrays of large light collectors deployed to exploit atmospheric Cherenkov radiation for gamma-ray astronomy at more than 100GeV, motivates the growing interest in application of intensity interferometry in astronomy. Indeed, planned arrays numbering up to one hundred telescopes will offer close to 5,000 baselines, ranging
Resonant structures based on amorphous silicon sub-oxide doped with Er3+ with silicon nanoclusters for an efficient emission at 1550 nm
physics.opticsD. S. L. Figueira, D. Mustafa, L. R. Tessler, N. C. Frateschi
We present a resonant approach to enhance 1550nm emission efficiency of amorphous silicon sub-oxide doped with Er3+ (a-SiOx<Er>) layers with silicon nanoclusters (Si-NC). Two distinct techniques were combined to provide a structure that allowed increasing approximately 12x the 1550nm emission. First, layers of SiO2 were obtained by conventional wet oxidation
M. V. Fedorov, Yu. M. Mikhailova, P. A. Volkov
A double-Gaussian model and the Schmidt modes are found for the biphoton wave function characterizing spontaneous parametric down-conversion with the degenerate collinear phase-matching of the type I and with a pulsed pump. The obtained results are valid for all durations of the pump pulses, short, long and intermediately long.
L. Fernández-Jambrina
In this lecture a new formalism for constructing electromagnetic surface sources for static axisymmetric electrovacs is presented. The electrostatic and magnetostatic sources are derived from the discontinuities of the scalar potentials. This formalism allows the inclusion of two kinds of dipole sources: Sheets of dipoles and the dipole moment of a distribut
Convergence of Polynomial Ergodic Averages of Several Variables for some Commuting Transformations
math.DSMichael C. R. Johnson
Let $(X,\mathcal{B},μ)$ be a probability space and let $T_1,..., T_l$ be $l$ commuting invertible measure preserving transformations \linebreak of $X$. We show that if $T_1^{c_1} ... T_l^{c_l}$ is ergodic for each $(c_1,...,c_l)\neq (0,...,0)$, then the averages $\frac{1}{|Φ_N|}\sum_{u\inΦ_N}\prod_{i=1}^r T_1^{p_{i1}(u)}... T_l^{p_{il}(u)}f_i$ converge in $L
Tian-Jun Li, Yongbin Ruan
This is a survey on symplectic birational geometry. In arbitrary dimension, this subject is centered around the notion of uniruledness. In low dimensions, we will also discuss Kodaira dimension and minimality.
L. Fernández-Jambrina
In this talk it is shown a way for constructing magnetic surface sources for stationary axisymmetric electrovac spacetimes possessing a non-smooth electromagnetic Ernst potential. The magnetic moment density is related to this lack of smoothness and its calculation involves solving a linear elliptic differential equation. As an application the results are us
Byung-Yoon Park, Vicente Vento
We review an approach, developed over the past few years, to describe hadronic matter at finite density and temperature, whose underlying theoretical framework is the Skyrme model, an effective low energy theory rooted in large $N_c$ QCD. In this approach matter is described by various crystal structures of skyrmions, classical topological solitons carrying
Roberto Fontana, Giovanni Pistone
The joint use of counting functions, Hilbert basis and Markov basis allows to define a procedure to generate all the fractions that satisfy a given set of constraints in terms of orthogonality. The general case of mixed level designs, without restrictions on the number of levels of each factor (like primes or power of primes) is studied. This new methodology
Vassilios G. Papageorgiou, Anastasios G. Tongas
We present Yang-Baxter maps associated to elliptic curves. They are related to discrete versions of the Krichever-Novikov and the Landau-Lifshits equations. A lifting of scalar integrable quad-graph equations to two-field equations is also shown.
Grégory Lafitte
We show some incompleteness results a la Chaitin using the busy beaver functions. Then, with the help of ordinal logics, we show how to obtain a theory in which the values of the busy beaver functions can be provably established and use this to reveal a structure on the provability of the values of these functions.
Olivier Bournez, Jérémie Chalopin, Johanne Cohen, Xavier Koegler
Population protocols have been introduced as a model of sensor networks consisting of very limited mobile agents with no control over their own movement: A collection of anonymous agents, modeled by finite automata, interact in pairs according to some rules. Predicates on the initial configurations that can be computed by such protocols have been characteriz
Nick Ramsey
We construct a rigid-analytic map from the the author's half-integral weight cuspidal eigencurve to its integral weight counterpart that interpolates the classical Shimura lifting.
Miljenko Cemeljic, Jose Gracia, Nektarios Vlahakis, Kanaris Tsinganos
Axisymmetric resistive MHD simulations for radially self-similar initial conditions are performed, using the NIRVANA code. The magnetic diffusivity could occur in outflows above an accretion disk, being transferred from the underlying disk into the disk corona by MHD turbulence (anomalous turbulent diffusivity), or as a result of ambipolar diffusion in parti
Andre Nathan, Valmir C. Barbosa
When a neuron fires and the resulting action potential travels down its axon toward other neurons' dendrites, the effect on each of those neurons is mediated by the weight of the synapse that separates it from the firing neuron. This weight, in turn, is affected by the postsynaptic neuron's response through a mechanism that is thought to underlie important p
David Doty, Matthew J. Patitz, Scott M. Summers
We prove that if a subset X of the integer Cartesian plane weakly self-assembles at temperature 1 in a deterministic (Winfree) tile assembly system satisfying a natural condition known as *pumpability*, then X is a finite union of doubly periodic sets. This shows that only the most simple of infinite shapes and patterns can be constructed using pumpable temp
Nick Ramsey
In this paper we define Banach spaces of overconvergent half-integral weight $p$-adic modular forms and Banach modules of families of overconvergent half-integral weight $p$-adic modular forms over admissible open subsets of weight space. Both spaces are equipped with a continuous Hecke action for which $U_{p^2}$ is moreover compact. The modules of families
Matthew Cook
Rule 110 is a cellular automaton that performs repeated simultaneous updates of an infinite row of binary values. The values are updated in the following way: 0s are changed to 1s at all positions where the value to the right is a 1, while 1s are changed to 0s at all positions where the values to the left and right are both 1. Though trivial to define, the b
On Nonoscillation of Mixed Advanced-Delay Differential Equations with Positive and Negative Coefficients
math.DSLeonid Berezansky, Elena Braverman, Sandra Pinelas
For a mixed (advanced--delay) differential equation with variable delays and coefficients $$ \dot{x}(t) \pm a(t)x(g(t)) \mp b(t)x(h(t)) = 0, t\geq t_0 $$ where $$ a(t)\geq 0, b(t)\geq 0, g(t)\leq t, h(t)\geq t $$ explicit nonoscillation conditions are obtained.
Cristina Cachero, Jesús Pardillo
Requirements engineering is known to be a key factor for the success of software projects. Inside this discipline, goal-oriented requirements engineering approaches have shown specially suitable to deal with projects where it is necessary to capture the alignment between system requirements and stakeholders' needs, as is the case of data-warehousing proj
M. R. Calvo, M. J. Caturla, D. Jacob, C. Untiedt
The dynamic deformation upon stretching of Ni nanowires as those formed with mechanically controllable break junctions or with a scanning tunneling microscope is studied both experimentally and theoretically. Molecular dynamics simulations of the breaking process are performed. In addition, and in order to compare with experiments, we also compute the transp
More than mass proportional heating of heavy ions by supercritical collisionless shocks in the solar corona
astro-ph.SRGaetano Zimbardo
We propose a new model for explaining the observations of more than mass proportional heating of heavy ions in the polar solar corona. We point out that a large number of small scale intermittent shock waves can be present in the solar corona. The energization mechanism is, essentially, the ion reflection off supercritical quasi-perpendicular collisionless s
Yuri Bozhkov
We establish a generalization to Riemannian manifolds of the Caffarelli-Kohn-Nirenberg inequality. The applied method is based on the use of conformal Killing vector fields and Enzo Mitidieri's approach to Hardy inequalities.
Minkowski Sum Construction and other Applications of Arrangements of Geodesic Arcs on the Sphere
cs.CGEfi Fogel
We present two exact implementations of efficient output-sensitive algorithms that compute Minkowski sums of two convex polyhedra in 3D. We do not assume general position. Namely, we handle degenerate input, and produce exact results. We provide a tight bound on the exact maximum complexity of Minkowski sums of polytopes in 3D in terms of the number of facet
Leonid Berezansky, Elena Braverman
The Bohl-Perron result on exponential dichotomy for a linear difference equation $$ x(n+1)-x(n) + \sum_{l=1}^m a_l(n)x(h_l(n))=0, h_l(n)\leq n, $$ states (under some natural conditions) that if all solutions of the non-homogeneous equation with a bounded right hand side are bounded, then the relevant homogeneous equation is exponentially stable. According to
Nick Ramsey
We introduce a geometric formalism for studying modular forms of half-integral weight and explore some of its basic properties. Geometric Hecke operators are constructed and some basic spaces of $p$-adic forms are introduced. The $p$-adic theory is greatly expanded in subsequent papers, making that part of this paper largely obsolete.
Cristian S. Calude
Universality is one of the most important ideas in computability theory. There are various criteria of simplicity for universal Turing machines. Probably the most popular one is to count the number of states/symbols. This criterion is more complex than it may appear at a first glance. In this note we review recent results in Algorithmic Information Theory an
Thomas Jagemann
The absolute magnitude of the brightest galaxy of clusters varies remarkably little and is nearly independent of all other physical properties of the cluster as, e.g., its spatial extension or its richness. The question arises whether the observed small scatter is compatible with the assumption of dynamical evolution of the cluster. This is investigated with
Sergey Verlan, Yurii Rogozhin
Symport/antiport P systems provide a very simple machinery inspired by corresponding operations in the living cell. It turns out that systems of small descriptional complexity are needed to achieve the universality by these systems. This makes them a good candidate for small universal devices replacing register machines for different simulations, especially
The Klein-Gordon equation with multiple tunnel effect on a star-shaped network: Expansions in generalized eigenfunctions
math.SPFelix Ali Mehmeti, Robert Haller-Dintelmann, Virginie Régnier
We consider the Klein-Gordon equation on a star-shaped network composed of n half-axes connected at their origins. We add a potential which is constant but different on each branch. The corresponding spatial operator is self-adjoint and we state explicit expressions for its resolvent and its resolution of the identity in terms of generalized eigenfunctions.
V. P. Konchakovski, M. Hauer, M. I. Gorenstein, E. L. Bratkovskaya
Particle number fluctuations and correlations in nucleus-nucleus collisions at SPS and RHIC energies are studied within the statistical hadron-resonance gas model in different statistical ensembles and in the Hadron-String-Dynamics (HSD) transport approach. Event-by-event fluctuations of the proton to pion and kaon to proton number ratios are calculated in t
Klaus Sutner
We introduce a formal definition of Wolfram's notion of computational process based on cellular automata, a physics-like model of computation. There is a natural classification of these processes into decidable, intermediate and complete. It is shown that in the context of standard finite injury priority arguments one cannot establish the existence of an
Nicolas Ollinger, Gaétan Richard
Signals are a classical tool used in cellular automata constructions that proved to be useful for language recognition or firing-squad synchronisation. Particles and collisions formalize this idea one step further, describing regular nets of colliding signals. In the present paper, we investigate the use of particles and collisions for constructions involvin
H. Witala, R. Skibinski, J. Golak, W. Glockle
We extend our approach to incorporate the proton-proton (pp) Coulomb force into the three-nucleon (3N) Faddeev calculations from elastic proton-deuteron (pd) scattering to the breakup process. The main new ingredient is a 3-dimensional screened pp Coulomb t-matrix obtained by a numerical solution of the 3-dimensional Lippmann-Schwinger equation. We demonstra
Jérôme Durand-Lose
This article aims at providing signal machines as small as possible able to perform any computation (in the classical understanding). After presenting signal machines, it is shown how to get universal ones from Turing machines, cellular-automata and cyclic tag systems. Finally a halting universal signal machine with 13 meta-signals and 21 collision rules is
Sergey Andreyev
All the modern day applications have the interface, absolutely defined by the developers. The use of adaptive interface or dynamic layout allows some variations, but even all of them are predetermined on the design stage, because the best reaction (from designer's view) on any possible users' movement was hardcoded. But there is a different world of
F. R. Ford, J. A. Gracey
We compute the two loop MSbar correction to the Gribov mass gap equation in the Landau gauge using the Gribov-Zwanziger Lagrangian with massive quarks included. The computation involves dilogarithms of complex arguments and reproduces the known gap equation when the quark mass tends to zero.
High quality epitaxial FeSe0.5Te0.5 thin films grown on SrTiO3 substrates by pulsed laser deposition
cond-mat.supr-conE. Bellingeri, R. Buzio, A. Gerbi, D. Marre'
Superconducting epitaxial FeSe0.5Te0.5 thin films were prepared on SrTiO3 (001) substrates by pulsed laser deposition. The high purity of the phase, the quality of the growth and the epitaxy were studied with different experimental techniques: X-rays diffraction, reflection high energy electron diffraction, scanning tunnelling microscopy and atomic force mic
Narad Rampersad, Jeffrey Shallit
We consider variations on the following problem: given an NFA M and a pattern p, does there exist an x in L(M) such that p matches x? We consider the restricted problem where M only accepts a finite language. We also consider the variation where the pattern p is required only to match a factor of x. We show that both of these problems are NP-complete. We als
Classification of the electronic correlation strength in the Fe-pnictides: The case of the parent compound BaFe2As2
cond-mat.str-elS. L. Skornyakov, A. V. Efremov, N. A. Skorikov, M. A. Korotin
Electronic correlations in the Fe-pnictide BaFe2As2 are explored within LDA+DMFT, the combination of density functional theory with dynamical mean-field theory. While the correlated band structure is substantially renormalized there is only little transfer of spectral weight. The computed k-integrated and k-resolved spectral functions are in good agreement w
Reduction algorithm for the NPMLE for the distribution function of bivariate interval censored data
stat.COMarloes H. Maathuis
We study computational aspects of the nonparametric maximum likelihood estimator (NPMLE) for the distribution function of bivariate interval censored data. The computation of the NPMLE consists of two steps: a parameter reduction step and an optimization step. In this paper we focus on the reduction step. We introduce two new reduction algorithms: the Tree a
A. G. Ramm
The governing equation is $[\nabla^2+k^2-q(x)]u=0$ in $\R^3$. It is shown that any desired potential $q(x)$, vanishing outside a bounded domain $D$, can be obtained if one embeds into D many small scatterers $q_m(x)$, vanishing outside balls $B_m:=\{x: |x-x_m|<a\}$, such that $q_m=A_m$ in $B_m$, $q_m=0$ outside $B_m$, $1\leq m \leq M$, $M=M(a)$. It is proved
Nicolas Ollinger
This talk advocates intrinsic universality as a notion to identify simple cellular automata with complex computational behavior. After an historical introduction and proper definitions of intrinsic universality, which is discussed with respect to Turing and circuit universality, we discuss construction methods for small intrinsically universal cellular autom
Planar polynomial vector fields having a polynomial first integral can be obtained from linear systems
math.CABelen Garcia, Hector Giacomini, Jesus Perez del Rio
We consider in this work planar polynomial differential systems having a polynomial first integral. We prove that these systems can be obtained from a linear system through a polynomial change of variables.
High-resolution inelastic X-ray scattering studies of the state-resolved differential cross-section of Compton excitations in helium atoms
physics.atom-phB. P. Xie, L. F. Zhu, K. Yang, B. Zhou
The state-resolved differential cross sections for both the 1s2 1S0 - 1s2s 1S0 monopolar transition and the 1s2 1S0 - 1s2p 1P1 dipolar transition of atomic helium have been measured over a large momentum transfer region by the high-resolution inelastic X-ray scattering (IXS) for the first time. The almost perfect match of the present measurement with the the
Alexander Okhotin
A restricted case of the Circuit Value Problem known as the Sequential NOR Circuit Value Problem was recently used to obtain very succinct examples of conjunctive grammars, Boolean grammars and language equations representing P-complete languages (Okhotin, http://dx.doi.org/10.1007/978-3-540-74593-8_23 "A simple P-complete problem and its representations
Laura A. Golick, Karen E. Daniels
The size-segregation of granular materials, a process colloquially known as the Brazil Nut Effect, has generally been thought to proceed faster the greater the size difference of the particles. We experimentally investigate sheared bidisperse granular materials as a function of the size ratio of the two species, and find that the mixing rate at low confining
Tackling the Gross-Pitaevskii energy functional with the Sobolev gradient - Analytical and numerical results
quant-phP. Kazemi, M. Eckart
In the first part of this contribution we prove the global existence and uniqueness of a trajectory that globally converges to the minimizer of the Gross-Pitaevskii energy functional for a large class of external potentials. Using the method of Sobolev gradients we can provide an explicit construction of this minimizing sequence. In the second part we numeri
Viktor V. Begun, Mark I. Gorenstein, Walter Greiner
We study a smooth crossover transition in the gas of quark-gluon bags. The equation of state at high temperature is that of the quark-gluon plasma. However, the system consists of the bags with finite volumes which are defined by the model parameters of the mass-volume bag spectrum. Possible structures in this {\it cluster} quark-gluon plasma are classified.
Magnetostructural Effect in the Multiferroic BiFeO3-BiMnO3 Checkerboard from First Principles
cond-mat.mtrl-sciL. Palova, P. Chandra, K. M. Rabe
Using first principles calculations, we present a magnetostructural effect in the BiFeO3-BiMnO3 nanocheckerboard that is not found in either bulk parent compound or in BiFeO3-BiMnO3 superlattices. We also demonstrate that the atomic-scale checkerboard has a multiferroic ground state with the desired properties of each constitutent material: polar and ferrima
Mari Kobayashi, Yingbin Liang, Shlomo Shamai, Merouane Debbah
We study the compound multi-input multi-output (MIMO) broadcast channel with confidential messages (BCC), where one transmitter sends a common message to two receivers and two confidential messages respectively to each receiver. The channel state may take one of a finite set of states, and the transmitter knows the state set but does not know the realization
Manfred Kudlek
The paper puts into discussion the concept of universality, in particular for structures not of the power of Turing computability. The question arises if for such structures a universal structure of the same kind exists or not. For that the construction of universal Turing machines and those with some constraints are presented in some detail.