April 2010 arXiv papers — page 25

Praveen Chaddah, Alok Banerjee

Metallic glasses are formed by splat-cooling; this ensures that atomic motions are arrested before the latent heat of solidification can be extracted. Glass is defined as a higher disorder metastable state with arrested kinetics. Arrested kinetics is a defining property of a glass, rather than structural disorder as, e.g., in amorphous silicon [1]. `Magnetic

Zoltan Kadar, Zoltan Zimboras

We investigate the entanglement entropy of a block of L sites in quasifree translation-invariant spin chains concentrating on the effect of reflection symmetry breaking. The majorana two-point functions corresponding to the Jordan-Wigner transformed fermionic modes are determined in the most general case; from these it follows that reflection symmetry in the

M. Iskin, A. L. Subasi

Similar to what has recently been achieved with Bose-Bose mixtures [Lamporesi et al., Phys. Rev. Lett. 104, 153202 (2010)], mixed-dimensional Fermi-Fermi mixtures can be created by applying a species-selective one-dimensional optical lattice to a two-species Fermi gas ($σ\equiv \{\uparrow, \downarrow \}$), such a way that only one of the species feel the lat

Alexander Getmanenko

The Witten Laplacian in one dimension is studied further by methods of resurgent analysis in order to approach Fukaya's conjectures relating WKB asymptotics and disc instantons. In this paper more precise connection formulae are presented, which allows the calculation of a subdominant exponential term in the hyperasymptotic expansion of a low-lying eigen

Richard P. Brent

Random number generators are widely used in practical algorithms. Examples include simulation, number theory (primality testing and integer factorization), fault tolerance, routing, cryptography, optimization by simulated annealing, and perfect hashing. Complexity theory usually considers the worst-case behaviour of deterministic algorithms, but it can also

Roumen Tsekov

A stochastic Langevin equation is derived, describing the thermal motion of a molecule immersed in a rested fluid of identical molecules. The fluctuation-dissipation theorem is proved and a number of correlation characteristics of the molecular Brownian motion are obtained.

Daniel Plaumann

Real algebraic geometry provides certificates for the positivity of polynomials on semi-algebraic sets by expressing them as a suitable combination of sums of squares and the defining inequalitites. We show how Putinar's theorem for strictly positive polynomials on compact sets can be applied in the case of strictly positive piecewise polynomials on a si

Hiroki Matui

We prove that all strongly outer Z^N-actions on a UHF algebra of infinite type are strongly cocycle conjugate to each other. We also prove that all strongly outer, asymptotically representable Z^N-actions on a unital simple AH algebra with real rank zero, slow dimension growth and finitely many extremal tracial states are cocycle conjugate to each other.

Daniele Rosso

In this paper we generalize to the case of partial flags a result proved both by Spaltenstein and by Steinberg that relates the relative position of two complete flags and the irreducible components of the flag variety in which they lie, using the Robinson-Schensted-Knuth correspondence.

Tatsuro Nishine, Akito Kobayashi, Yoshikazu Suzumura

The polarization function of electrons with the tilted Dirac cone found in organic conductors is studied using the tilted Weyl equation. The dynamical property is explored based on the analytical treatment of the particle-hole excitation. It is shown that the polarization function as the function of both the frequency and the momentum exhibits cusps and nonm

D. D. Xu, S. Mao, A. Cooper, J. Wang

Lensing flux-ratio anomalies have been frequently observed and taken as evidence for the presence of abundant dark matter substructures in lensing galaxies, as predicted by the cold dark matter (CDM) model of cosmogony. In previous work, we examined the cusp-caustic relations of the multiple images of background quasars lensed by galaxy-scale dark matter hal

Hideo Kodama, Keiki Saito, Akihiro Ishibashi

The local void model has recently attracted considerable attention because it can explain the apparent accelerated expansion of the present universe without introducing dark energy. However, in order to justify this model as an alternative to the standard $Λ$CDM cosmology, the model should be tested by various observations, such as the CMB temperature anisot

S. Brendle, F. C. Marques, A. Neves

Consider a compact Riemannian manifold M of dimension n whose boundary \partial M is totally geodesic and is isometric to the standard sphere S^{n-1}. A natural conjecture of Min-Oo asserts that if the scalar curvature of M is at least n(n-1), then M is isometric to the hemisphere S_+^n equipped with its standard metric. This conjecture is inspired by the po

Hiroshi Fukuyama, Isamu Iwanari

In this paper we prove that a morphism between schemes or stacks naturally corresponds to a symmetric monoidal functor between stable infinity-categories of quasi-coherent complexes. It can be viewed as a derived analogue of Tannaka duality. As a consequence, we deduce that an algebraic stack satisfying a certain condition can be recovered from the stable in

Tina Kahniashvili, Axel Brandenburg, Alexander G. Tevzadze, Bharat Ratra

We perform direct numerical simulations of forced and freely decaying 3D magnetohydrodynamic turbulence in order to model magnetic field evolution during cosmological phase transitions in the early Universe. Our approach assumes the existence of a magnetic field generated either by a process during inflation or shortly thereafter, or by bubble collisions dur

A. A. Lopatin

A minimal (by inclusion) generating set for the algebra of semi-invariants of a quiver of dimension (2,...,2) is established over an infinite field of arbitrary characteristic. The mentioned generating set consists of the determinants of generic matrices and the traces of tree paths of pairwise different multidegrees, where in the case of characteristic diff

Antonio H. Castro Neto

Graphene research is currently one of the largest fields in condensed matter. Due to its unusual electronic spectrum with Dirac-like quasiparticles, and the fact that it is a unique example of a metallic membrane, graphene has properties that have no match in standard solid state textbooks. In these lecture notes, I discuss some of these properties that are

Andrew Hodges

An account is given of how the 'box integrals', as used for one-loop calculations in massless field theory, appear in momentum-twistor geometry. Particular attention is paid to the role of compact contour integration in representing the Feynman propagator in twistor space. An explicit calculation of all the box integrals, using only elementary method

Motokazu Takizawa, Ryo Nagino, Kyoko Matsushita

We investigate the impact of mergers on the mass estimation of galaxy clusters using $N$-body + hydrodynamical simulation data. We estimate virial mass from these data and compare it with real mass. When the smaller subcluster's mass is larger than a quarter of that of the larger one, virial mass can be larger than twice of the real mass. The results str

Matt Gibson, Imran A. Pirwani

We consider the problem of finding a lowest cost dominating set in a given disk graph containing $n$ disks. The problem has been extensively studied on subclasses of disk graphs, yet the best known approximation for disk graphs has remained $O(\log n)$ -- a bound that is asymptotically no better than the general case. We improve the status quo in two ways: f

Kyle F. Kaplan, J. Xavier Prochaska, Stephane Herbert-Fort, Sara L. Ellison

With the Blue Channel Spectrograph (BCS) on the MMT telescope, we have obtained spectra to the atmospheric cutoff of quasars previously known to show at least one absorption system at z>1.6 with very strong metal lines (candidate metal-strong damped Lya systems; cMSDLAs). The BCS/MMT spectra yield precise estimates of the HI column densities (NHI) of the sys

Edmund R. Meyer, John L. Bohn

We consider ultracold, chemically reactive scattering collisions of the diatomic molecules KRb. When two such molecules collide in an ultracold gas, we find that they are energetically forbidden from reacting to form the trimer species K$_2$Rb or Rb$_2$K, hence can only react via the bond-swapping reaction 2KRb $\to$ K$_2$ + Rb$_2$. Moreover, the tiny energy

L. M. Chasman

The vibrational frequencies of a plate under tension are given by the eigenvalues $ω$ of the equation $Δ^2u-τΔu=ωu$. This paper determines the eigenfunctions and eigenvalues of this bi-Laplace problem on the ball under natural (free) boundary conditions. In particular, the fundamental modes --- the eigenfunctions of the lowest nonzero eigenvalue --- are iden

V. V. Dobrovitski, G. de Lange, D. Ristè, R. Hanson

Long-time dynamical decoupling and quantum control of qubits require high-precision control pulses. Full characterization (quantum tomography) of imperfect pulses presents a bootstrap problem: tomography requires initial states of a qubit which can not be prepared without imperfect pulses. We present a protocol for pulse error analysis, specifically tailored

Guillermo Gonzalez, Melody Carlson, Ryan W. Tobin

We report the results of abundance analyses of new samples of stars with planets and stars without detected planets. We employ these data to compare abundance-condensation temperature trends in both samples. We find that stars with planets have more negative trends. In addition, the more metal-rich stars with planets display the most negative trends. These r

Iván Angiono, Agustín García Iglesias

We show that any finite-dimensional pointed Hopf algebra over an abelian group $Γ$ such that its infinitesimal braiding is of standard type is generated by group-like and skew-primitive elements. This fact agrees with the long-standing conjecture by Andruskiewitsch and Schneider. We also show that the quantum Serre relations hold in any coradically graded po

John F. Beacom

The Diffuse Supernova Neutrino Background (DSNB) is the weak glow of MeV neutrinos and antineutrinos from distant core-collapse supernovae. The DSNB has not been detected yet, but the Super-Kamiokande (SK) 2003 upper limit on the electron antineutrino flux is close to predictions, now quite precise, based on astrophysical data. If SK is modified with dissolv

Zazralt Magic, Aldo Serenelli, Achim Weiss, Brian Chaboyer

The open cluster M67 has solar metallicity and an age of about 4Gyr. The turn-off mass is close to the minimum mass for which solar metallicity stars develop a convective core during main sequence evolution as a result of the development of hydrogen burning through the CNO-cycle. The morphology of the color-magnitude-diagram (CMD) of M67 around the turn-off

Benjamin Gray, Ho Nyung Lee, Jian Liu, J. Chakhalian

Through the utilization of element-resolved polarized x-ray probes, the electronic and magnetic state of an artificial La2FeCrO6 double perovskite were explored. Applying unit-cell level control of thin film growth on SrTiO3 (111), the rock salt double perovskite structure can be created for this system, which does not have an ordered perovskite phase in the

Amit Chakrabarti, Graham Cormode, Ranganath Kondapally, Andrew McGregor

This paper makes three main contributions to the theory of communication complexity and stream computation. First, we present new bounds on the information complexity of AUGMENTED-INDEX. In contrast to analogous results for INDEX by Jain, Radhakrishnan and Sen [J. ACM, 2009], we have to overcome the significant technical challenge that protocols for AUGMENTE

M. E. McCulloch

It has recently been observed that there are no disc galaxies with masses less than 10^9 M_solar and this cutoff has not been explained. It is shown here that this minimum mass can be predicted using a model that assumes that 1) inertia is due to Unruh radiation, and 2) this radiation is subject to a Hubble-scale Casimir effect. The model predicts that as th

S. Frank, C. Péroux

We searched for evidence of reddening of background SDSS QSO spectra due to dust in intervening DLA systems. We utilise the Data Releases 5 and 7 to arrive at sample sizes of 475 (DR5) and 676 (DR7) absorbers, based on two different published lists of SDSS DLAs. Both samples span roughly the redshift range of 2.2 < z_abs < 5.2, with a mean of z~3.0, and the

Bhuvnesh Jain, Justin Khoury

Modifications of general relativity provide an alternative explanation to dark energy for the observed acceleration of the universe. We review recent developments in modified gravity theories, focusing on higher dimensional approaches and chameleon/f(R) theories. We classify these models in terms of the screening mechanisms that enable such theories to appro

Robert Fesen, Dan Milisavljevic

The nebula J222557+601148, tentatively identified by Morris et al. (2006) as a young Galactic supernova remnant (SNR) from Spitzer Galactic First Look Survey images and a follow-up mid-infrared spectrum, is unlikely to be a SNR remnant based on Halpha, [O III], [S II] images and low dispersion optical spectra. The object is seen in Halpha and [O III] 5007 im

Mubdi Rahman, Norman Murray

We examine the thirteen most luminous sources in the WMAP free-free map using the Spitzer GLIMPSE and MSX surveys to identify massive star formation regions, emitting one-third of the Galactic free-free luminosity. We identify star forming regions by a combination of bubble morphology in 8 $\micronm$ (PAH) emission and radio recombination line radial velocit

E. Ricciardelli, A. Franceschini

We present a new semi-analytical model of galaxy formation, GECO (Galaxy Evolution COde), aimed at a better understanding of when and how the two processes of star formation and galaxy assembly have taken place. Our model is structured into a Monte Carlo algorithm based on the Extended Press-Schechter theory, for the representation of the merging hierarchy o

Alex H. Parker, JJ. Kavelaars

Two populations of minor bodies in the outer Solar System remain particularly elusive: Scattered Disk objects and Sedna-like objects. These populations are important dynamical tracers, and understanding the details of their spatial- and size-distributions will enhance our understanding of the formation and on-going evolution of the Solar System. By using new

Alex H. Parker, JJ. Kavelaars

Digital co-addition of astronomical images is a common technique for increasing signal-to-noise and image depth. A modification of this simple technique has been applied to the detection of minor bodies in the Solar System: first stationary objects are removed through the subtraction of a high-SN template image, then the sky motion of the Solar System bodies

Martin Bucher, Carla Sofia Carvalho, Kavilan Moodley, Mathieu Remazeilles

We explore the reconstruction of the gravitational lensing field of the cosmic microwave background in real space showing that very little statistical information is lost when estimators of short range on the celestial sphere are used in place of the customary estimators in harmonic space, which are nonlocal and in principle require a simultaneous analysis o

A. B. Klimov, G. Bjork, J. Soderholm, L. S. Madsen

We propose an operational degree of polarization in terms of the variance of the projected Stokes vector minimized over all the directions of the Poincaré sphere. We examine the properties of this degree and show that some problems associated with the standard definition are avoided. The new degree of polarization is experimentally determined using two examp

Hakan Topakkaya, Zhengdao Wang

Network coding and cooperative communication have received considerable attention from the research community recently in order to mitigate the adverse effects of fading in wireless transmissions and at the same time to achieve high throughput and better spectral efficiency. In this work, we design and analyze deterministic and random network coding schemes

Ryan Martin, Brendon Stanton

An $r$-identifying code on a graph $G$ is a set $C\subset V(G)$ such that for every vertex in $V(G)$, the intersection of the radius-$r$ closed neighborhood with $C$ is nonempty and unique. On a finite graph, the density of a code is $|C|/|V(G)|$, which naturally extends to a definition of density in certain infinite graphs which are locally finite. We prese

B. Pritychenko

Recommended 2 $β$ (2 $ν$) half-life values and their systematics were analyzed in the frame- work of a simple empirical approach. T$^{2 ν}$$_{1/2}$ ~ 1/E$^{8}$ trend has been observed for $^{128,130}$Te recommended values. This trend was used to predict T$^{2 ν}$$_{1/2}$ for all isotopes of interest. Current results were compared with other theoretical and e

F. Persson, C. M. Wilson, M. Sandberg, P. Delsing

We have fabricated a single Cooper-pair box (SCB) together with an on-chip lumped element resonator. By utilizing the quantum capacitance of the SCB, its state can be read out by detecting the phase of a radio-frequency (rf) signal reflected off the resonator. The resonator was optimized for fast readout. By studying quasiparticle tunneling events in the SCB

A. Asensio Ramos, A. Lopez Ariste

The image degradation produced by atmospheric turbulence and optical aberrations is usually alleviated using post-facto image reconstruction techniques, even when observing with adaptive optics systems. These techniques rely on the development of the wavefront using Zernike functions and the non-linear optimization of a certain metric. The resulting optimiza

Ezekiel Okike

Chidamber and Kemerer first defined a cohesion measure for object-oriented software - the Lack of Cohesion in Methods (LCOM) metric. This paper presents a pedagogic evaluation and discussion about the LCOM metric using field data from three industrial systems. System 1 has 34 classes, System 2 has 383 classes and System 3 has 1055 classes. The main objective

G. K. Kharate, V. H. Patil

In Image Compression, the researchers&#39; aim is to reduce the number of bits required to represent an image by removing the spatial and spectral redundancies. Recently discrete wavelet transform and wavelet packet has emerged as popular techniques for image compression. The wavelet transform is one of the major processing components of image compression. T

Kruti Dangarwala, Jigar Shah

Just about all the newest living room audio-video electronics and PC multimedia products being designed today will incorporate some form of compressed digitized-audio processing capability. Audio compression reduces the bit rate required to represent an analog audio signal while maintaining the perceived audio quality. Discarding inaudible data reduces the s

Kamal Sarkar, Mita Nasipuri, Suranjan Ghose

Keyphrases provide a simple way of describing a document, giving the reader some clues about its contents. Keyphrases can be useful in a various applications such as retrieval engines, browsing interfaces, thesaurus construction, text mining etc.. There are also other tasks for which keyphrases are useful, as we discuss in this paper. This paper describes a

Chinmay Hegde, Richard G. Baraniuk

Compressive Sensing (CS) is a new technique for the efficient acquisition of signals, images, and other data that have a sparse representation in some basis, frame, or dictionary. By sparse we mean that the N-dimensional basis representation has just K<<N significant coefficients; in this case, the CS theory maintains that just M = K log N random linear sign

Nattapon Pannurat, Nittaya Kerdprasop, Kittisak Kerdprasop

Maintaining a legacy database is a difficult task especially when system documentation is poor written or even missing. Database reverse engineering is an attempt to recover high-level conceptual design from the existing database instances. In this paper, we propose a technique to discover conceptual schema using the association mining technique. The discove

Antonio Cimino, Francesco Longo, Giovanni Mirabelli

Nowadays there is a large availability of discrete event simulation software that can be easily used in different domains: from industry to supply chain, from healthcare to business management, from training to complex systems design. Simulation engines of commercial discrete event simulation software use specific rules and logics for simulation time and eve

Vishal Sharma, Harsh Kumar Verma

Software effort estimation at early stages of project development holds great significance for the industry to meet the competitive demands of today&#39;s world. Accuracy, reliability and precision in the estimates of effort are quite desirable. The inherent imprecision present in the inputs of the algorithmic models like Constructive Cost Model (COCOMO) yie

E. Ramirez Barreto, Y. A. Coutinho, J. Sá Borges

We search for signatures of the extra neutral gauge boson $ Z^\prime$, predicted in some extensions of the Standard Model, from the analysis of some distributions for $p + p \longrightarrow μ^+ + μ^- + X$, where the only exotic particle involved is $ Z^\prime$. In addition to the invariant mass and charge asymmetry distributions, we propose in our search to

Amir Mollanejad, Leili Mohammad Khanli, Mohammad Zeynali

Wireless sensor networks (WSNs) are commonly used in various ubiquitous and pervasive applications. Due to limited power resources, the optimal dynamic base station (BS) replacement could be Prolong the sensor network lifetime. In this paper we&#39;ll present a dynamic optimum method for base station replacement so that can save energy in sensors and increas

Ramazan Havangi, Mohammad Ali Nekoui, Mohammad Teshnehlab

Extended Kalman Filter (EKF) has been a popular approach to localization a mobile robot. However, the performance of the EKF and the quality of the estimation depends on the correct a priori knowledge of process and measurement noise covariance matrices (Qk and Rk, respectively). Imprecise knowledge of these statistics can cause significant degradation in pe

Nikhil Raj, R. K. Sharma

The Glottal Source is an important component of voice as it can be considered as the excitation signal to the voice apparatus. Nowadays, new techniques of speech processing such as speech recognition and speech synthesis use the glottal closure and opening instants. Current models of the glottal waves derive their shape from approximate information rather th

Richard Cleyton, Gabriela P. Ovando, Yat Sun Poon

A complex symplectic structure on a Lie algebra $\lie h$ is an integrable complex structure $J$ with a closed non-degenerate $(2,0)$-form. It is determined by $J$ and the real part $Ω$ of the $(2,0)$-form. Suppose that $\lie h$ is a semi-direct product $\lie g\ltimes V$, and both $\lie g$ and $V$ are Lagrangian with respect to $Ω$ and totally real with respe

Aissam Berrahou, Mourad Rafi, Mohsine Eleuldj

In this paper, we present Digital Rights Management systems (DRMS) which are becoming more and more complex due to technology revolution in relation with telecommunication networks, multimedia applications and the reading equipments (Mobile Phone, IPhone, PDA, DVD Player,..). The complexity of the DRMS, involves the use of new tools and methodologies that su

Rosmayati Mohemad, Abdul Razak Hamdan, Zulaiha Ali Othman, Noor Maizura Mohamad Noor

The successful execution of a construction project is heavily impacted by making the right decision during tendering processes. Managing tender procedures is very complex and uncertain involving coordination of many tasks and individuals with different priorities and objectives. Bias and inconsistent decision are inevitable if the decision-making process is

A. Mosavi

Real-life engineering optimization problems need Multiobjective Optimization (MOO) tools. These problems are highly nonlinear. As the process of Multiple Criteria Decision-Making (MCDM) is much expanded most MOO problems in different disciplines can be classified on the basis of it. Thus MCDM methods have gained wide popularity in different sciences and appl

Rahul Kala, Harsh Vazirani, Anupam Shukla, Ritu Tiwari

Handwriting Recognition enables a person to scribble something on a piece of paper and then convert it into text. If we look into the practical reality there are enumerable styles in which a character may be written. These styles can be self combined to generate more styles. Even if a small child knows the basic styles a character can be written, he would be

Fatima-Zahra Belouadha, Hajar Omrana, Ounsa Roudies

Composing Web services is a convenient means of dealing with complex requests. However, the number of Web services on the Internet is increasing. This explains the growing interest in composing Web services automatically. Nevertheless, the Web services&#39; semantics is necessary for any dynamic composition process. In this article, we present an MDA approac

D. Chasse, A. -M. S. Tremblay

The Josephson effect is generally described as Cooper pair tunneling, but it can also be understood in a more general context. The DC Josephson effect is the pseudo-Goldstone boson of two coupled systems with a broken continuous abelian U(1) symmetry. Hence, an analog should exist for systems with broken continuous non-Abelian symmetries. To exhibit the gene

Laura De Giusti, Franco Chichizola, Marcelo Naiouf, Armando De Giusti

The AMTHA (Automatic Mapping Task on Heterogeneous Architectures) algorithm for task-to-processors assignment and the MPAHA (Model of Parallel Algorithms on Heterogeneous Architectures) model are presented. The use of AMTHA is analyzed for multicore processor-based architectures, considering the communication model among processes in use. The results obtaine

P. Xu, J. O. Piatek, P. -H. Lin, B. Sipos

When a Mott metal-insulator transition is inhibited by a small amount of disorder in the layered dichalcogenide 1T-TaS$_2$, an inhomogeneous superconducting state arises below T=2.1 K, and coexists with a nearly-commensurate charge-density-wave. By angle-resolved photoelectron spectroscopy (ARPES) we show that it emerges from a bad metal state with strongly

Zaenal Akbar

Software piracy, the illegal using, copying, and resale of applications is a major concern for anyone develops software. Software developers also worry about their applications being reverse engineered by extracting data structures and algorithms from an application and incorporated into competitor&#39;s code. A defense against software piracy is watermarkin

Gintaras Valiukevicius

Algebraic operations are understood as topologiztion of algebra. They become an example of simplest convergence space. In our article the convergence is a arbitrary multivalued appointment. The continuity of some mapping between two convergence spaces is defined as a property of commuting squares. The adherence space is defined as a special convergence. The

Craig V. Spencer, Trevor D. Wooley

Consider a form $g(x_1,...,x_s)$ of degree $d$, having coefficients in the completion $F_q((1/t))$ of the field of fractions $F_q(t)$ associated to the finite field $F_q$. We establish that whenever $s>d^2$, then the form $g$ takes arbitrarily small values for non-zero arguments $x\in F_q[t]^s$. We provide related results for problems involving distribution

Iain K. Cooper, Stephen F. King, Christoph Luhn

We propose a supersymmetric (SUSY) SU(5) Grand Unified Theory (GUT) including a single right-handed neutrino singlet and an adjoint matter representation below the GUT scale and extend this model to include an A4 family symmetry and a gauged anomaly-free Abelian group. In our approach hierarchical neutrino masses result from a combined type I and type III se

James Cheney

Provenance, or information about the sources, derivation, custody or history of data, has been studied recently in a number of contexts, including databases, scientific workflows and the Semantic Web. Many provenance mechanisms have been developed, motivated by informal notions such as influence, dependence, explanation and causality. However, there has been

Benjamin Koch

It is shown that the equations of relativistic Bohmian mechanics for multiple bosonic particles have a dual description in terms of a classical theory of conformally &#34;curved&#34; space-time. This shows that it is possible to formulate quantum mechanics as a purely classical geometrical theory. The results are further generalized to interactions with an e

Pascale Garaud, Gordon I. Ogilvie, Neil Miller, Stephan Stellmach

We propose a closure model for the transport of entropy and momentum in astrophysical turbulence, intended for application to rotating stellar convective regions. Our closure model is first presented in the Boussinesq formalism, and compared with laboratory and numerical experimental results on Rayleigh-Benard convection and Homogeneous Rayleigh-Benard conve

Olga V. Baturina, Alexander V. Bulatov, Vadim F. Krotov

Necessary optimality conditions and numerical methods for solving an optimal control problem for a linear continuous-time dynanical system with controlled coefficients and quadratic goal functional are discussed.

Oyvind Gron, Steinar Johannesen

In the present article we find a new class of solutions of Einstein&#39;s field equations. It describes stationary, cylindrically symmetric spacetimes with closed timelike geodesics everywhere outside the symmetry axis. These spacetimes contain a magnetic field parallel to the axis, a perfect fluid with constant density and pressure, and Lorentz invariant va

Costanza Conti, Luca Gemignani, Lucia Romani

In this paper we describe a general, computationally feasible strategy to deduce a family of interpolatory non-stationary subdivision schemes from a symmetric non-stationary, non-interpolatory one satisfying quite mild assumptions. To achieve this result we extend our previous work [C.Conti, L.Gemignani, L.Romani, Linear Algebra Appl. 431 (2009), no. 10, 197

Kazuhiro Yamamoto, Gen Nakamura, Gert Huetsi, Tatsuya Narikawa

A constraint on the viable f(R) model is investigated by confronting theoretical predictions with the multipole power spectrum of the luminous red galaxy sample of the Sloan Digital Sky survey data release 7. We obtain a constraint on the Compton wavelength parameter of the f(R) model on the scales of cosmological large-scale structure. A prospect of constra

Atreju Tauschinsky, Rutger M. T. Thijssen, S. Whitlock, H. B. van Linden van den Heuvell

We demonstrate spatially resolved, coherent excitation of Rydberg atoms on an atom chip. Electromagnetically induced transparency (EIT) is used to investigate the properties of the Rydberg atoms near the gold coated chip surface. We measure distance dependent shifts (~10 MHz) of the Rydberg energy levels caused by a spatially inhomogeneous electric field. Th

Steven M. Anlage

We summarize progress in the development and application of metamaterial structures utilizing superconducting elements. After a brief review of the salient features of superconductivity, the advantages of superconducting metamaterials over their normal metal counterparts are discussed. We then present the unique electromagnetic properties of superconductors

Valery Weber, Safir Merchant, Purushottam D. Dixit, D. Asthagiri

In the free energy of hydration of a solute, the chemical contribution is given by the free energy required to expel water molecules from the coordination sphere and the packing contribution is given by the free energy required to create the solute-free coordination sphere (the observation volume) in bulk water. With the SPC/E water model as a reference, we

Karim Kellay, Pascal Lefèvre

We characterize the compactness of composition operators; in term of generalized Nevanlinna counting functions, on a large class of Hilbert spaces of analytic functions, which can be viewed between the Bergman and the Dirichlet spaces

Sergey Kitaev, Jeffrey Remmel

An unlabeled poset is said to be (2+2)-free if it does not contain an induced subposet that is isomorphic to 2+2, the union of two disjoint 2-element chains. Let $p_n$ denote the number of (2+2)-free posets of size $n$. In a recent paper, Bousquet-Mélou et al.\cite{BCDK} found, using so called ascent sequences, the generating function for the number of (2+2)

Bikashkali Midya, Barnana Roy, Rajkumar Roychoudhury

It is shown that the PT symmetric Hamiltonian with the periodic potential V(x) = 4 cos^2 x + 4 i V_0 sin 2x can be mapped into a Hermitian Hamiltonian for $V_0<0.5$, by a similarity transformation. It is also shown that there exist a second critical point of the potential V(x), apart from the known critical point $V_0=0.5$, for $V_0^c ~ .888437$ after which

R. Nepstad, T. Birkeland, M. Førre

Few-photon induced breakup of helium is studied using a newly developed ab initio numerical framework for solving the six-dimensional time-dependent Schroedinger equation. We present details of the method and calculate (generalized) cross sections for the process of two-photon nonsequential (direct) double ionization at photon energies ranging from 39.4 to 5

A. S. Belozerov, A. I. Poteryaev, V. I. Anisimov

The influence of Coulomb correlation on magnetic and spectral properties in metallic rutile phase of vanadium dioxide is studied by state of the art LDA+DMFT method. Calculation results in strongly correlated metallic state with an effective mass renormalization $m^*/m\approx2$. Uniform magnetic susceptibility shows Curie-Weiss temperature dependence with ef

Yuan-Jie Du, G. J. Qiao, J. L. Han, K. J. Lee

Pulsed high energy radiation from pulsars is not yet completely understood. In this paper, we use the 3D self-consistent annular gap model to study light curves for both young and millisecond pulsars observed by the Fermi Gamma-ray Space Telescope. The annular gap can generate high energy emission for short-period pulsars. The annular gap regions are so larg

Jouni Parkkonen, Frédéric Paulin

Given an integral indefinite binary Hermitian form f over an imaginary quadratic number field, we give a precise asymptotic equivalent to the number of nonequivalent representations, satisfying some congruence properties, of the rational integers with absolute value at most s by f, as s tends to infinity.

Igor Lesanovsky, Beatriz Olmos, Juan P. Garrahan

We study the coherent quantum evolution of a closed and driven mesoscopic chain of two-level systems that interact via the van-der-Waals interaction in their excited state. The Hamiltonian consists of a part corresponding to a classical lattice gas and an off-diagonal driving term without classical counterpart. We show that in a certain parameter range the l

Dmitry Agafontsev

Extensive numerical simulations were performed to investigate all stages of modulation instability development from the initial pulse of pico-second duration in photonic crystal fiber: quasi-solitons and dispersive waves formation, their interaction stage and the further propagation. Comparison between 4 different NLS-like systems was made: the classical NLS

P. A. Evans, R. Willingale, J. P. Osborne, P. T. O&#39;Brien

Context: Gamma Ray Burst models predict the broadband spectral evolution and the temporal evolution of the energy flux. In contrast, standard data analysis tools and data repositories provide count-rate data, or use single flux conversion factors for all of the data, neglecting spectral evolution. Aims: To produce Swift BAT and XRT light curves in flux units

Luigi Del Debbio, Biagio Lucini, Agostino Patella, Claudio Pica

We study the gauge sector of Minimal Walking Technicolor, which is an SU(2) gauge theory with nf=2 flavors of Wilson fermions in the adjoint representation. Numerical simulations are performed on lattices Nt x Ns^3, with Ns ranging from 8 to 16 and Nt=2Ns, at fixed β=2.25, and varying the fermion bare mass m0, so that our numerical results cover the full ran

David M. Acreman, Kevin A. Douglas, Clare L. Dobbs, Christopher M. Brunt

Using the Torus radiative transfer code we produce synthetic observations of the 21 cm neutral hydrogen line from an SPH simulation of a spiral galaxy. The SPH representation of the galaxy is mapped onto an AMR grid, and a ray tracing method is used to calculate 21 cm line emission for lines of sight through the AMR grid in different velocity channels and sp

J. Peer, A. Kendl

The electromagnetic fields associated with tortuous lightning channels are usually characterised by a pronounced fine structure. This work investigates and quantifies the effects of channel tortuosity on the return stroke electromagnetic field shapes in the close lightning environment (the range up to 100m from the lightning striking point). General equation

I. Pallecchi, L. Pellegrino, N. Banerjee, M. Cantoni

We probe spin transport in Cu_{2}O by measuring spin valve effect in La_{0.7}Sr_{0.3}MnO_{3}/Cu_{2}O/Co and La_{0.7}Sr_{0.3}MnO_{3}/Cu_{2}O/La_{0.7}Sr_{0.3}MnO_{3} epitaxial heterostructures. In La_{0.7}Sr_{0.3}MnO_{3}/Cu_{2}O/Co systems we find that a fraction of out-of-equilibrium spin polarized carrier actually travel across the Cu_{2}O layer up to distan

John Cardy

A review is given of quantum network models in class C which, on a suitable 2d lattice, describe the spin quantum Hall plateau transition. On a general class of graphs, however, many observables of such models can be mapped to those of a classical walk in a random environment, thus relating questions of quantum and classical localization. In many cases it is

Luigi Del Debbio, Biagio Lucini, Agostino Patella, Claudio Pica

We investigate the structure and the novel emerging features of the mesonic non-singlet spectrum of the Minimal Walking Technicolor (MWT) theory. Precision measurements in the nonsinglet pseudoscalar and vector channels are compared to the expectations for an IR-conformal field theory and a QCD-like theory. Our results favor a scenario in which MWT is (almos

Julie Greensmith, Uwe Aickelin, Steve Cayzer

Dendritic cells are antigen presenting cells that provide a vital link between the innate and adaptive immune system. Research into this family of cells has revealed that they perform the role of coordinating T-cell based immune responses, both reactive and for generating tolerance. We have derived an algorithm based on the functionality of these cells, and

M. Novello

A mechanism in which gravity is the responsible for the generation of the mass of scalar bosons and fermions was proposed recently [arXiv:1003.5126]. The purpose of the present paper is to extend this scheme to vector bosons. The main characteristic of this mechanism is that the gravitational field acts really as a catalyzer, once the final expression of the

Luis A. Anchordoqui, Haim Goldberg, Dariusz Gora, Thomas Paul

The Pierre Auger (cosmic ray) Observatory provides a laboratory for studying fundamental physics at energies far beyond those available at colliders. The Observatory is sensitive not only to hadrons and photons, but can in principle detect ultrahigh energy neutrinos in the cosmic radiation. Interestingly, it may be possible to uncover new physics by analyzin

Rachel Baile, Jean-Francois Muzy, Philippe Poggi

This paper describes a statistical method for short-term forecasting of surface layer wind velocity amplitude relying on the notion of continuous cascades. Inspired by recent empirical findings that suggest the existence of some cascading process in the mesoscale range, we consider that wind speed can be described by a seasonal component and a fluctuating pa