September 2007 arXiv papers — page 24

J. P. Lansberg, B. Pire, L. Szymanowski

We give a brief overview of the theoretical status of the Transition Distribution Amplitudes and discuss their experimental near future.

C. Casiraghi, S. Pisana, K. S. Novoselov, A. K. Geim

We report strong variations in the Raman spectra for different single-layer graphene samples obtained by micromechanical cleavage, which reveals the presence of excess charges, even in the absence of intentional doping. Doping concentrations up to ~10^13 cm-2 are estimated from the G peak shift and width, and the variation of both position and relative inten

Michael Blank

For a class of expanding maps with neutral singularities we prove the validity of a finite rank approximation scheme for the analysis of Sinai-Ruelle-Bowen measures. Earlier results of this sort were known only in the case of hyperbolic systems.

O. Absil, V. Coude du Foresto, M. Barillot, M. R. Swain

Detecting the presence of circumstellar dust around nearby solar-type main sequence stars is an important pre-requisite for the design of future life-finding space missions such as ESA's Darwin or NASA's Terrestrial Planet Finder (TPF). The high Antarctic plateau may provide appropriate conditions to perform such a survey from the ground. We investig

Marcel Blattner, Alexander Hunziker, Paolo Laureti

Recommender systems are crucial tools to overcome the information overload brought about by the Internet. Rigorous tests are needed to establish to what extent sophisticated methods can improve the quality of the predictions. Here we analyse a refined correlation-based collaborative filtering algorithm and compare it with a novel spectral method for recommen

K. C. Rule, A. U. B. Wolter, S. Süllow, D. A. Tennant

We present a specific heat and inelastic neutron scattering study in magnetic fields up into the 1/3 magnetization plateau phase of the diamond chain compound azurite Cu$_3$(CO$_3$)$_2$(OH)$_2$. We establish that the magnetization plateau is a dimer-monomer state, {\it i.e.}, consisting of a chain of $S = 1/2$ monomers, which are separated by $S = 0$ dimers

Didier Henrion, Jean Bernard Lasserre, Johan Lofberg

We describe a major update of our Matlab freeware GloptiPoly for parsing generalized problems of moments and solving them numerically with semidefinite programming.

Didier Henrion, Jerome Malick

This document is an introduction to the Matlab package SDLS (Semi-Definite Least-Squares) for solving least-squares problems over convex symmetric cones. The package is shortly presented through the addressed problem, a sketch of the implemented algorithm, the syntax and calling sequences, a simple numerical example and some more advanced features. The imple

Elie Feder, David Garber

In this paper, we cope with the following problem: compute the size of the convex hull of a configuration C, where the given data is the number of separating lines between any two points of the configuration (where the lines are generated by pairs of other points of the configuration). We give an algorithm for the case that the convex hull is of size 3, and

W. N. Cottingham

This paper is concerned with the physics of meson decays to J/psi and phi.These decays have been observed at the Tevatron [7] and, in particular, should be copiously observed at the LHCb detector. This paper gives a concise presentation of the basic physics analysis and a general formalism for analyzing the signals of CP violation.

P. Di Matteo, F. Combes, I. Chilingarian, A. -L. Melchior

We have undertaken a large set of simulations of galaxy interactions and mergers (GalMer Project) in order to study the physical processes related to galaxy encounters. All morphological types along the Hubble sequence are considered in the initial conditions of the two colliding galaxies, with varying bulge-to-disk ratios and gas mass fractions. Different t

G. Beskin, A. Biryukov, S. Karpov, V. Plokhotnichenko

General properties of accretion onto isolated stellar mass black holes in the Galaxy are discussed. An analysis of plasma internal energy growth during the infall is performed. Adiabatic heating of collisionless accretion flow due to magnetic adiabatic invariant conservation is 25% more efficient than in the standard non-magnetized gas case. It is shown that

Eli Bagno, David Garber, Toufik Mansour

We define new statistics, (c, d)-descents, on the colored permutation groups Z_r \wr S_n and compute the distribution of these statistics on the elements in these groups. We use some combinatorial approaches, recurrences, and generating functions manipulations to obtain our results.

A. Fiasson, J. A. Hinton, Y. Gallant, A. Marcowith

The H.E.S.S. telescope array has observed the complex Monoceros Loop SNR/Rosette Nebula region which contains unidentified high energy EGRET sources and potential very-high-energy (VHE) gamma-ray source. We announce the discovery of a new point-like VHE gamma-ray sources, HESS J0632+057. It is located close to the rim of the Monoceros SNR and has no clear co

Anton Biryukov, Gregory Beskin, Sergey Karpov, Lisa Chmyreva

The measurements of pulsar frequency second derivatives have shown that they are 1e2...1e6 times larger than expected for standard pulsar spin-down law. Moreover, the second derivatives as well as braking indices are even negative for about half the pulsars. We explain these paradoxical results on the basis of the statistical analysis of the rotational param

Yoav Berlatzky, Shachar Klaiman

An ab initio analytical model for Fano resonances in two-channel systems is presented. We find that the lineshape parameter q factors into a background contribution q_b that depends only on the uncoupled channels and an interaction contribution q_i that is affected by the coupling between the channels, revealing how the overall lineshape parameter q may be c

J. M. Butterworth

The ATLAS and CMS experiments will take first data soon. I consider here the prospects for new physics (excluding SUSY) with a few inverse fb of data. This means processes with signal cross sections of a few 100 fb or less, with clear and fairly simple signatures - precision comparison of data to Standard Model tails will take longer, needing more luminosity

A. A. Yurova, A. V. Yurov

We show that $(1+2)$ nonlinear Klein-Gordon equation with negative coupling admits an exact solution which appears to be the linear superposition of the plane wave and the nonsingular rational soliton. We show that the same approach allows to construct the solution of similar properties for the Euclidean $ϕ^4$ model with broken symmetry. Interestingly, this

Sascha Bornhauser, Manuel Drees, Herbi K. Dreiner, Jong Soo Kim

In this paper we compute electroweak contributions to the production of squark pairs at hadron colliders. These include the exchange of electroweak gauge bosons in the s-channel as well as electroweak gaugino exchange in the t- and/or u-channel. In many cases these can interfere with the dominant QCD contributions. As a result, we find sizable contributions

S. -K. Lee, M. V. Romalis

High-permeability magnetic shields generate magnetic field noise that can limit the sensitivity of modern precision measurements. We show that calculations based on the fluctuation-dissipation theorem allow quantitative evaluation of magnetic field noise, either from current or magnetization fluctuations, inside enclosures made of high-permeability materials

Wen-Rong Dai, De-Xing Kong, Kefeng Liu

In this paper we introduce and study a new kind of hyperbolic geometric flows --dissipative hyperbolic geometric flow. This kind of flow is defined by a system of quasilinear wave equations with dissipative terms. Some interesting exact solutions are given, in particular, a new concept-- hyperbolic Ricci soliton is introduced and some of its geometric proper

Ben M. Leith, Alex B. Nielsen

We study the static, spherically symmetric black hole solutions for a non-minimally coupled multi-scalar theory. We find numerical solutions for values of the scalar fields when a certain constraint on the maximal charge is satisfied. Beyond this constraint no black hole solutions exist. This constraint therefore corresponds to extremal solutions, however, t

T. A. Larsson

Canonical quantization of gravity requires knowledge about the representation theory of its constraint algebra, which is physically equivalent to the algebra of arbitrary 4-diffeomorphisms. All interesting lowest-energy representations are projective, making the relevant algebra into a four-dimensional generalization of the Virasoro algebra. Such diffeomorph

T. A. Larsson

I review the multi-dimensional generalizations of the Virasoro algebra, i.e. the non-central Lie algebra extensions of the algebra vect(N) of general vector fields in N dimensions, and its Fock representations. Being the Noether symmetry of background independent theories such as N-dimensional general relativity, this algebra is expected to be relevant to th

Omar Benhar

I discuss the relation between the nuclear response and the Green function describing the propagation of a nucleon in the nuclear medium. Within this formalism, the widely used expressions in terms of spectral functions can be derived in a consistent and rigorous fashion. The results of recent applications to the study of the inclusive electron-nucleus cross

Munazza Zulfiqar Ali, Tariq Abdullah

The linear properties of the angular gap in a one dimensional photonic band gap structure containing single negative material layers are investigated. This gap forms at oblique incidence due to total internal reflection into air when the Snell's law breaks down and its lower edge occurs at the frequency where the refractive index of one or both layers of

G. I. Garas'ko

It is shown that in the weak field approximation the new geometrical approach can lead to the linear field equations for the several independent fields. For the stronger fields and in the second order approximation the field equations become non-linear, and the fields become dependent. This breaks the superposition principle for every separate field and prod

R. Vogt

We assess the theoretical uncertainties on the total charm cross section. We discuss the importance of the quark mass, the scale choice and the parton densities on the estimate of the uncertainty. We conclude that due to the small charm quark mass, which amplifies the effect of the other parameters in the calculation, the uncertainty on the total charm cross

Shina Tan

It is shown that the effective interaction strength of three bosons at small collision energies can be extracted from their wave function at zero energy. An asymptotic expansion of this wave function at large interparticle distances is derived, from which is defined a quantity $D$ named three-body scattering hypervolume, which is an analog of the two-body sc

Y. Katsukawa, T. Yokoyama, T. E. Berger, K. Ichimoto

The Solar Optical Telescope (SOT) aboard HINODE successfully and continuously observed a formation process of a light bridge in a matured sunspot of the NOAA active region 10923 for several days with high spatial resolution. During its formation, many umbral dots were observed emerging from the leading edges of penumbral filaments, and intruding into the umb

Alexander Altland, V. Gurarie

We formulate and approximately solve a specific many-body generalization of the Landau-Zener problem. Unlike with the single particle Landau-Zener problem, our system does not abide in the adiabatic ground state, even at very slow driving rates. The structure of the theory suggests that this finding reflects a more general phenomenon in the physics of adiaba

Manabu Miyamoto, Atushi Tanaka

Anholonomies in the parametric dependences of the eigenvalues and the eigenvectors of Floquet operators that describe unit time evolutions of periodically driven systems, e.g., kicked rotors, are studied. First, an example of the anholonomies induced by a periodically pulsed rank-1 perturbation is given. As a function of the strength of the perturbation, the

R. Q. Wu, Y. P. Feng

First principles calculations based on density functional theory (DFT) are performed to study the electronic properties of Mg acceptors in AlN at the presence of oxygen. It is found that Mg and O tend to form complexes like Mg-O, Mg$_2$-O, Mg$_3$-O and Mg$_4$-O which have activation energies about 0.23 eV lower than that of Mg (except of the passive Mg-O). T

Judit X. Madarasz, Istvan Nemeti, Gergely Szekely

Several versions of the Gravitational Time Dilation effect of General Relativity are formulated by the use of Einstein's Equivalence Principle. It is shown that all of them are logical consequence of a first-order axiom system of Special Relativity extended to accelerated observers.

Monica Vazquez Acosta

Contact interactions offer a general framework for describing a new interaction with a scale above the energy scale probed. These interactions can occur if the Standard Model particles are composite or if new heavy particles are exchanged. The discovery potential of contact interactions at the LHC in dimuon and dijet final states at startup and the asymptoti

P. Firth, M. J. Drinkwater, E. A. Evstigneeva, M. D. Gregg

We have obtained spectroscopic redshifts of colour-selected point sources in four wide area VLT-FLAMES fields around the Fornax Cluster giant elliptical galaxy NGC 1399, identifying as cluster members 30 previously unknown faint (-10.5<M_g&#39;<-8.8) compact stellar systems (CSS), and improving redshift accuracy for 23 previously catalogued CSS. By amalgamat

Nu. Komin, S. Carrigan, A. Djannati-Ataï, Y. A. Gallant

The source HESS J1809-193 was discovered in 2006 in data of the Galactic Plane survey, followed by several re-observations. It shows a hard gamma-ray spectrum and the emission is clearly extended. Its vicinity to PSR J1809-1917, a high spin-down luminosity pulsar powerful enough to drive the observed gamma-ray emission, makes it a plausible candidate for a T

C. Barbero, Ling-Fong Li, G. Lopez Castro, A. Mariano

We compute the rates of semileptonic B_A \to B_Bl^-l^- (l=e or μ) hyperon transitions in a model where intermediate states involve loops of baryons and a Majorana neutrino. These rates turn out to be well below present experimental bounds and other theoretical estimates. From the experimental upper limit on the Ξ^- \to pμ^-μ^- decay, we derive the bound <m_{

Neil A. Butcher, Paul M. Saffin

We investigate the dynamics of the geometric transitions associated to compactified spacetimes. By including the dynamics of gravity we are able to follow the evolution of collapsing cycles as they attempt to undergo a topology changing transition. Rather than achieving this singular geometry we find that one of two scenarios occur, depending on the initial

S. N. Balashov, K. Green, M. G. D. van der Grinten, P. G. Harris

This document is a copy of the original 2003 proposal for the construction grant for the CryoEDM Experiment at ILL, Grenoble. It is here made publicly available as a technical reference source for interested parties. It does not necessarily represent the final configuration of the experiment. Items pertaining to costs, personnel etc. have been removed.

Ichiro Oda

We investigate the Higgs mechanism for gravity, which has been recently put forward by &#39;t Hooft, when the Polyakov-type action for scalar fields is added to the original action. We find that from the Polyakov-type action, it is very natural to derive an &#39;alternative&#39; metric tensor composed of the scalar fields. The positivity condition on the det

Andrew M. C. Dawes, Lucas Illing, Joel A. Greenberg, Daniel J. Gauthier

We demonstrate an all-optical switch that operates at ultra-low-light levels and exhibits several features necessary for use in optical switching networks. An input switching beam, wavelength $λ$, with an energy density of $10^{-2}$ photons per optical cross section [$σ=λ^2/(2π)$] changes the orientation of a two-spot pattern generated via parametric instabi

Masahito Kubo, Takaaki Yokoyama, Yukio Katsukawa, Bruce W Lites

Continuous observations of a flare productive active region 10930 were successfully carried out with the Solar Optical Telescope onboard the Hinode spacecraft during 2007 December 6 to 19. We focus on the evolution of photospheric magnetic fields in this active region, and magnetic field properties at the site of the X3.4 class flare, using a time series of

K. M. Huffenberger, I. J. O&#39;Dwyer, K. M. Gorski, B. D. Wandelt

We present several diverse applications of the spherical fast convolution method suggested by Wandelt and Gorski (2001), which is useful for studies of telescope optical properties and for construction of shaped filters for analysis of all-sky data. We study sidelobe pickup in three design concepts for the CALISTO infrared telescope. The beam convolution all

Bhuvnesh Jain, Pengjie Zhang

Modified gravity theories have richer observational consequences for large-scale structure than conventional dark energy models, in that different observables are not described by a single growth factor even in the linear regime. We examine the relationships between perturbations in the metric potentials, density and velocity fields, and discuss strategies f

Taeyoung Lee, Melvin Leok, N. Harris McClamroch

A time optimal attitude control problem is studied for the dynamics of a rigid body. The objective is to minimize the time to rotate the rigid body to a desired attitude and angular velocity while subject to constraints on the control input. Necessary conditions for optimality are developed directly on the special orthogonal group using rotation matrices. Th

Chao Chen, Daniel Freedman

In the companion paper, we measured homology classes and computed the optimal homology basis. This paper addresses two related problems, namely, localization and stability. We localize a class with the cycle minimizing a certain objective function. We explore three different objective functions, namely, volume, diameter and radius. We show that it is NP-hard

Sergiy Maksymenko

Let $g:\mathbb{R}^2\to\mathbb{R}$ be a homogeneous polynomial of degree $p>1$, $G=(-g&#39;_{y}, g&#39;_{x})$ be its Hamiltonian vector field, and $G_t$ be the local flow generated by $G$. Denote by $E(G,O)$ the space of germs of $C^{\infty}$ diffeomorphisms $(\mathbb{R}^2,O)\to(\mathbb{R}^2,O)$ that preserve orbits of $G$. Let also $E_{\mathrm{id}}(G,O)$ be

F. R. Klinkhamer, M. Risse

A particularly simple Lorentz-violating modification of the Maxwell theory of photons maintains gauge invariance, CPT, and renormalization. This modified-Maxwell theory, coupled to standard Dirac particles, involves nineteen dimensionless &#34;deformation parameters.&#34; Ten of these parameters lead to birefringence and are already tightly constrained by as

Dibyendu Roy, N. Kumar

The Landauer scattering approach to 4-probe resistance is revisited for the case of a d-dimensional disordered resistor in the presence of decoherence. Our treatment is based on an invariant-embedding equation for the evolution of the coherent reflection amplitude coefficient in the length of a 1-dimensional disordered conductor, where decoherence is introdu

Zihua Weng

The paper studies the validity of Maxwell equation in the case for coexistence of electromagnetic field and gravitational field. With the algebra of quaternions, the Newton&#39;s law of gravitation is the same as that in classical theory of gravitational field. Meanwhile the Maxwell equation is identical with that in classical theory of electromagnetic field

A. Bershadskii

Transition to condensate state in the degenerate gas of bosons is studied using the Gross-Pitaevskii equation. It is shown that adiabatic invariance of an enstrophy (mean squared vorticity) based on a generalized vorticity $curl (|ψ|^2 {\bf v})/|ψ|^2$, controls dynamics of the transitional turbulence just before formation of the condensate with its tangles o

Andrew N. Norris

The model of Zhao and Suo can be readily generalized to predict the critical breakdown electric field $E_c$ value of elastomers with arbitrary elastic strain energy function. An explicit expression for $E_c$ is presented for elastomeric thin films under biaxial strain and comparisons are made with experimental data using a two term Ogden rubber elasticity mo

Michael Greenblatt

The elementary resolution of singularities algorithm of the author&#39;s earlier paper (math.CA/0609217) is developed further, replacing the quasibump functions in the blown up coordinates with the characteristic function of a rectangle times a smooth function. Such functions are easier to deal with, and as application the existence of asymptotic expansions

Tao Ma

The Hamiltonian H of one-body Maryland model is defined as the sum of a linear unperturbed Hamiltonian H_0 and the interaction V, which is a Toeplitz matrix. Maryland model with a doubly infinite Hilbert space are exactly solved. Special cases of one-body Maryland model include the original Maryland model (Phys. Rev. Lett. 49, 833 (1982) and Physica 10D, 369

Luca Mazzucato, Yaron Oz, Shimon Yankielowicz

We consider intersecting brane configurations realizing N=2 supersymmetric gauge theories broken to N=1 by multitrace superpotentials, and softly to N=0. We analyze, in the framework of M5-brane wrapping a curve, the supersymmetric vacua and the analogs of spontaneous supersymmetry breaking and soft supersymmetry breaking in gauge theories. We show that the

Thomas Chen, Juerg Froehlich, Alessandro Pizzo

We construct infraparticle scattering states for Compton scattering in the standard model of non-relativistic QED. In our construction, an infrared cutoff initially introduced to regularize the model is removed completely. We rigorously establish the properties of infraparticle scattering theory predicted in the classic work of Bloch and Nordsieck from the 1

Zaixing huang

As a general rule, it is considered that the global gauge invariance of an action integral does not cause the occurrence of gauge field. However, in this paper we demonstrate that when the so-called localized assumption is excluded, the gauge field will be induced by the global gauge invariance of the action integral. An example is given to support this conc

E. Lakshtanov

We consider quantum scattering from a compactly supported potential $q$. The semiclassical limit amounts to letting the wavenumber $k \to \infty$ while rescaling the potential as $k^2 q$ (alternatively, one can scale Planck&#39;s constant $\hbar \searrow 0$). It is well-known that, under appropriate conditions, for $\om \in \bbS_{n-1}$ such that there is exa

Mehran Bagheri

Using a perturbative approach, the effects of the energy gap induced by the Aharonov-Bohm (AB) flux on the transport properties of defective metallic single-walled carbon nanotubes (MSWCNTs) are investigated. The electronic waves scattered back and forth by a pair of impurities give rise to Fabry-Perot oscillations which constitutes a coherent backscattering

M. C. Kumar, Prakash Mathews, V. Ravindran, Anurag Tripathi

We have considered the di-photon production with unparticle at LHC. The contributions of spin-0 and spin-2 unparticle to the di-photon production are studied in the invariant mass and other kinematical distributions, along with their dependencies on the model dependent parameters. The signal corresponding to the unparticle is significant for moderate couplin

Lucia Di Vizio

We prove an ultrametric q-difference version of the Maillet-Malgrange theorem, on the Gevrey nature of formal solutions of nonlinear analytic q-difference equations. Since °_q and \ord_q define two valuations on {\mathbb C}(q), we obtain, in particular, a result on the growth of the degree in q and the order at q of formal solutions of nonlinear q-difference

Ya. S. Greenberg, E. Il&#39;ichev

We use the density matrix formalism to analyze the interaction of interferometer-type superconducting qubits with a high quality tank circuit, which frequency is well below the gap frequency of a qubit. We start with the ground state characterization of the superconducting flux and charge qubits. Then, by making use of a dressed state approach we describe th

Chao-Jun Feng

A general holographic relation between UV and IR cutoff of an effective field theory is proposed. Taking the IR cutoff relevant to the dark energy as the Hubble scale, we find that the cosmological constant is highly suppressed by a numerical factor and the fine tuning problem seems alleviative. We also use different IR cutoffs to study the case in which the

Yasuhide Sota, Osamu Iguchi, Tohru Tashiro, Masahiro Morikawa

We propose the self-organized relaxation process which drives a collisionless self-gravitating system (SGS) to the equilibrium state satisfying local virial (LV) relation. During the violent relaxation process, particles can move widely within the time interval as short as a few free fall times, because of the effective potential oscillations. Since such par

Weimin Chen, Slawomir Kwasik

A study on the relation between the smooth structure of a symplectic homotopy K3 surface and its symplectic symmetries is initiated. A measurement of exoticness of a symplectic homotopy K3 surface is introduced, and the influence of an effective action of a K3 group via symplectic symmetries is investigated. It is shown that an effective action by various ma

Daryl Geller, Azita Mayeli

We show that one can characterize the Besov spaces on a smooth compact oriented Riemannian manifold, for the full range of indices, through a knowledge of the size of frame coefficients, using the frames we have constructed in [8].

K. -W. Lee, W. E. Pickett

The double perovskite \bnoo with heptavalent Os ($d^1$) is observed to remain in the ideal cubic structure ({\it i.e.} without orbital ordering) despite single occupation of the $t_{2g}$ orbitals, even in the ferromagnetically ordered phase below 6.8 K. Analysis based on the {\it ab initio} dispersion expressed in terms of an Os $t_{2g}$-based Wannier functi

C. Carloganu, A. -M. Magnan

The CALICE Si-W electromagnetic calorimeter has been tested with electron beams (1 to 6 GeV) at DESY in May 2006, as well as electrons (6 to 45 GeV) and hadrons (6 to 80 GeV) at CERN in August and October 2006. Several millions of events have been taken at different incident angles and three beam impact positions. The ECAL calibration is performed with muon

A. I. Shapiro, S. V. Berdyugina, D. M. Fluri, J. O. Stenflo

Weak entangled magnetic fields with mixed polarity occupy the main part of the quiet Sun. The Zeeman effect diagnostics fails to measure such fields because of cancellation in circular polarization. However, the Hanle effect diagnostics, accessible through the second solar spectrum, provides us with a very sensitive tool for studying the distribution of weak

Scott A. Wolpert

Convexity properties of Weil-Petersson geodesics on the Teichmüller space of punctured Riemann surfaces are investigated. A normal form is presented for the Weil-Petersson Levi-Civita connection for pinched hyperbolic metrics. The normal form is used to establish approximation of geodesics in boundary spaces. Considerations are combined to establish convexit

Thayne Currie, Scott Kenyon, Zoltan Balog, George Rieke

We describe Spitzer/MIPS observations of the double cluster, h and $χ$ Persei, covering a $\sim$ 0.6 square-degree area surrounding the cores of both clusters. The data are combined with IRAC and 2MASS data to investigate $\sim$ 616 sources from 1.25-24 $μm$. We use the long-baseline $K_{s}$-[24] color to identify two populations with IR excess indicative of

Lorenz Meier, Gian Salis, Ivan Shorubalko, Emilio Gini

Spin-orbit coupling is a manifestation of special relativity. In the reference frame of a moving electron, electric fields transform into magnetic fields, which interact with the electron spin and lift the degeneracy of spin-up and spin-down states. In solid-state systems, the resulting spin-orbit fields are referred to as Dresselhaus or Rashba fields, depen

Iryna Egorova, Johanna Michor, Gerald Teschl

We develop direct and inverse scattering theory for Jacobi operators with steplike coefficients which are asymptotically close to different finite-gap quasi-periodic coefficients on different sides. We give a complete characterization of the scattering data, which allow unique solvability of the inverse scattering problem in the class of perturbations with f

Vukosi N. Marivate, Fulufhelo V. Nelwamodo, Tshilidzi Marwala

Data collection often results in records that have missing values or variables. This investigation compares 3 different data imputation models and identifies their merits by using accuracy measures. Autoencoder Neural Networks, Principal components and Support Vector regression are used for prediction and combined with a genetic algorithm to then impute miss

Morgan Le Delliou, O. Bertolami, F. Gil Pedro

We find that the Abell Cluster A586 exhibits evidence of the interaction between dark matter and dark energy and argue that this interaction suggests evidence of violation of the Equivalence Principle. This violation is found in the context of two different models of dark energy-dark matter interaction.

Daniel Alpay, Simeon Reich, David Shoikhet

We use reproducing kernel methods to study various rigidity problems. The methods and setting allow us to also consider the non-positive case.

E. Parizot

While the completion of the Pierre Auger Observatory (or simply ``Auger&#39;&#39;) is still underway, the 5165 km^2.sr.yr integrated acceptance accumulated since the January 1st, 2004 is now significantly larger than what was gathered by the previous experiments dedicated to the detection of ultra-high-energy cosmic rays (UHECRs). We report on the developmen

Jack W. Sulentic, Sebastian Zamfir, Paola Marziani, Deborah Dultzin

The 4D Eigenvector 1 parameter space was introduced seven years ago as an attempt at multiwavelength spectroscopic representation of quasars. It appears to be the most effective diagnostic space for unifying the diversity of broad line AGN. This progress report shows that the diagnostic power of 4DE1 is confirmed using optical spectra from the SDSS, UV spect

A. Makarovski, A. Zhukov, J. Liu, G. Finkelstein

We find that electrons in single-wall carbon nanotubes may propagate substantial distances (tens of nanometers) under the metal contacts. We perform four-probe transport measurements of the nanotube conductance and observe significant deviations from the standard Kirchhoff&#39;s circuit rules. Most noticeably, injecting current between two neighboring contac

V. V. Bol&#39;ginov, O. M. Vyaselev, V. N. Shilov

The magnetic and transport properties of $Pd_{0.99}Fe_{0.01}$ thin films have been studied. We have found that the Curie temperature of the films is about 20 K and the magnetic properties strongly depend on temperature below $T_{Curie}$. We have also fabricated the set of superconductor-ferromagnet-superconductor josephson junctions $Nb-PdFe-Nb$. The tempera

Roger A. Horn, Vladimir V. Sergeichuk

It is known that any square matrix over any field F is congruent to its transpose. We show that they are also *congruent with respect to any nonidentity involution on F.

Genrich R. Belitskii, Vladimir V. Sergeichuk

In representation theory, the problem of classifying pairs of matrices up to simultaneous similarity is used as a measure of complexity; classification problems containing it are called wild problems. We show in an explicit form that this problem contains all classification matrix problems given by quivers or posets. Then we prove that it does not contain (b

C. Sasaki, B. Friman, K. Redlich

We briefly summarize the properties of conserved charge fluctuations as a sensitive probe for the QCD phase transitions. We discuss the density fluctuations which play a significant role to search for the critical end point. The importance of spinodal instabilities to distinguish the first-order phase transition is also indicated.

Vladimir V. Sergeichuk

We consider a large class of matrix problems, which includes the problem of classifying arbitrary systems of linear mappings. For every matrix problem from this class, we construct Belitskii&#39;s algorithm for reducing a matrix to a canonical form, which is the generalization of the Jordan normal form, and study the set C(m,n) of indecomposable canonical m-

V. M. Red&#39;kov

The monopole singularity string, infinite direct line in the rest reference frame, is considered as a rigid physical line, and behavior of its geometrical form under the Lorentz transformations is studied. The method to test the form of any rigid line or surface in relativistical terms is based on the use of light signals emitted from the origin of the refer

Ee Chang-Young, Hoil Kim

In this paper we construct quantum theta functions over noncommutative T^d with general embeddings. Manin has constructed quantum theta functions from the lattice embedding into vector space x finite group. We extend Manin&#39;s construction of quantum thetas to the case of general embedding of vector space x lattice x torus. It turns out that only for the v

Genrich Belitskii, Maxim Bershadsky, Vladimir V. Sergeichuk

We give a canonical form of m-by-2-by-2 spatial matrices for equivalence over any field.

C. Charlot

Recent studies in ATLAS and CMS experiments for the reconstruction and identification of electrons and photons using full Monte Carlo and testbeam data are reported

WA98 Collaboration, M. M. Aggarwal

Two-proton and two-deuteron correlations have been studied in the target fragmentation region of central Pb+Pb collisions at 158 A GeV. Protons and deuterons were measured with the Plastic Ball spectrometer of the WA98 experiment at the CERN SPS. The results of one-dimensional and multi-dimensional analyses using both the Bertsch-Pratt and Yano-Koonin-Podgor

Dorina Strori, Ahmet Bombaci, Haluk Bingol

Language is one of the most important aspects of human cognition; it represents the way we think, act and communicate with each other. Each language has its own history, background, and form. A language represents a lot of important cultural aspects of the nation speaking it. Languages differ and so do cultures. In this paper we analyze cultural differences

Bishnu P. Lamichhane, Laura Rebollo-Neira

The role of sparse representations in the context of structured noise filtering is discussed. A strategy, especially conceived so as to address problems of an ill posed nature, is presented. The proposed approach revises and extends the Oblique Matching Pursuit technique. It is shown that, by working with an orthogonal projection of the signal to be filtered

C. C. Hsu, A. Dettlaff, D. Fink, F. Goebel

The MAGIC 17m diameter Cherenkov telescope will be upgraded with a second telescope within the year 2007. The camera of MAGIC-II will include several new features compared to the MAGIC-I camera. Photomultipliers with the highest available photon collection efficiency have been selected. A modular design allows easier access and flexibility to test new photod

Roger A. Horn, Vladimir V. Sergeichuk

Canonical forms for congruence and *congruence of square complex matrices were given by Horn and Sergeichuk in [Linear Algebra Appl. 389 (2004) 347-353], based on Sergeichuk&#39;s paper [Math. USSR, Izvestiya 31 (3) (1988) 481-501], which employed the theory of representations of quivers with involution. We use standard methods of matrix analysis to prove di

Ling Li, Giulio Manico, Emanuele Congiu, Joe Roser

Experimental results on the formation of molecular hydrogen on amorphous silicate surfaces are presented and analyzed using a rate equation model. The energy barriers for the relevant diffusion and desorption processes are obtained. They turn out to be significantly higher than those obtained for polycrystalline silicates, demonstrating the importance of gra

Thomas P. Branson

We give an introductory account of functional determinants of elliptic operators on manifolds and Polyakov-type formulas for their infinitesimal and finite conformal variations. We relate this to extremal problems and to the Q-curvature on even-dimensional conformal manifolds. The exposition is self-contained, in the sense of giving references sufficient to

Vladimir V. Sergeichuk

Paul Van Dooren [Linear Algebra Appl. 27 (1979) 103-140] constructed an algorithm for the computation of all irregular summands in Kronecker&#39;s canonical form of a matrix pencil. The algorithm is numerically stable since it uses only unitary transformations. We extend Paul Van Dooren&#39;s algorithm to the matrices of a cycle of linear mappings.

Thomas Brüstle, Vladimir V. Sergeichuk

The problem of classifying modules over a tame algebra A reduces to a block matrix problem of tame type whose indecomposable canonical matrices are zero- or one-parameter. Respectively, the set of nonisomorphic indecomposable modules of dimension at most d divides into a finite number f(d,A) of modules and one-parameter series of modules. We prove that the n

Dmitri Millionschikov

We compute explicitly the adjoint cohomology of two N-graded Lie algebras of maximal class (infinite dimensional filiform Lie algebras) m_0 and m_2. It is known that up to an isomorphism there are only three N-graded Lie algebras of the maximal class. The third algebra from this list is the &#34;positive&#34; part L_1 of the Witt (or Virasoro) algebra and it

Shoji Kato

The amplification of disk oscillations resulting from nonlinear resonant couplings between the oscillations and a disk deformation is examined. The disk is geometrically thin and general relativistic with a non-rotating central source. A Lagrangian formulation is adopted. The author examined the same problem a few years ago, but here we derive a general stab