April 2008 arXiv papers — page 35

Oleg V. Gutik, Dušan Pagon, Dušan Repovš

We study chains in an $H$-closed topological partially ordered space. We give sufficient conditions for a maximal chain $L$ in an $H$-closed topological partially ordered space such that $L$ contains a maximal (minimal) element. Also we give sufficient conditions for a linearly ordered topological partially ordered space to be $H$-closed. We prove that any $

Gareth Hughes

Some problems with the mathematical analysis on which the UK Non-Native Organism Risk Assessment Scheme is based are outlined.

Ratthachat Chatpatanasiri, Teesid Korsrilabutr, Pasakorn Tangchanachaianan, Boonserm Kijsirikul

This paper focuses on the problem of kernelizing an existing supervised Mahalanobis distance learner. The following features are included in the paper. Firstly, three popular learners, namely, "neighborhood component analysis", "large margin nearest neighbors" and "discriminant neighborhood embedding", which do not have kernel version

Oleg Gutik, Jimmie Lawson, Dušan Repovš

We introduce the notion of semigroup with a tight ideal series and investigate their closures in semitopological semigroups, particularly inverse semigroups with continuous inversion. As a corollary we show that the symmetric inverse semigroup of finite transformations $\mathscr{I}_λ^n$ of the rank $\leqslant n$ is algebraically closed in the class of (semi)

Valery Van Kerrebroeck, Enzo Marinari

We introduce Loop Ranking, a new ranking measure based on the detection of closed paths, which can be computed in an efficient way. We analyze it with respect to several ranking measures which have been proposed in the past, and are widely used to capture the relative importance of the vertices in complex networks. We argue that Loop Ranking is a very approp

Jan Maas, Jan van Neerven

Let (E,H,mu) be an abstract Wiener space and let D_V := VD, where D denotes the Malliavin derivative and V is a closed and densely defined operator from H into another Hilbert space G. Given a bounded operator B on G, coercive on the closure of the range of V, we consider the realisation of the operator D_V* B D_V in L^p(E,mu) for 1<p<\infty. Our main result

Henning Krause

These are the notes for a course on representations of quivers for second year students in Paderborn in summer 2007. My aim was to provide a basic introduction without using any advanced methods. It turns out that a good knowledge of linear algebra is sufficient for proving Gabriel&#39;s theorem. Thus we classify the quivers of finite representation type and

A. Bandini, I. Longhi, S. Vigni

If F is a global function field of characteristic p>3, we employ Tate&#39;s theory of analytic uniformization to give an alternative proof of a theorem of Igusa describing the image of the natural Galois representation on torsion points of non-isotrivial elliptic curves defined over F. Along the way, using basic properties of Faltings heights of elliptic cur

Nimish A. Shah

We show that a multiplicative form of Dirichlet's theorem on simultaneous Diophantine approximation as formulated by Minkowski, cannot be improved for almost all points on any analytic curve on R^k which is not contained in a proper affine subspace. Such an investigation was initiated by Davenport and Schmidt in the late sixties. The Diophantine problem is t

Tomasz Paterek, Borivoje Dakic, Caslav Brukner

We introduce a hierarchical classification of theories that describe systems with fundamentally limited information content. This property is introduced in an operational way and gives rise to the existence of mutually complementary measurements, i.e. a complete knowledge of future outcome in one measurement is at the expense of complete uncertainty in the o

Herman Bayem, Yannick Phulpin, Philippe Dessante, Julien Bect

This paper addresses the problem of predicting a wind farm&#39;s power generation when no or few statistical data is available. The study is based on a time-series wind speed model and on a simple dynamic model of a DFIG wind turbine including cut-off and cut-in behaviours. The wind turbine is modeled as a stochastic hybrid system with three operation modes.

K. Kitagawa, R. Higashinaka, K. Ishida, Y. Maeno

We have performed nuclear quadrupole resonance (NQR) experiments on $^{47}$Ti nuclei in Dy$_2$Ti$_2$O$_7$ in the temperature range 70 -- 300 K in order to investigate the dynamics of $4f$ electrons with strong Ising anisotropy. A significant change of the NQR frequency with temperature was attributed to the variation of the quadrupole moment of Dy $4f$ elect

V. N. Minasyan

First, it is shown that the creation of the spinless ion pairs in the lattice, which are hold by the binding with neighbor ion pairs together regarded as covalent. These ion pairs are created by the repulsive potential interaction of two ions which is bound as linear oscillator. The repulsive S-wave scattering between ion pairs and electrons is transformed t

Chady Elmir, Jacques Lafontaine

The systole of a compact non simply connected Riemannian manifold is the smallest length of a non-contractible closed curve ; the systolic ratio is the quotient $(\mathrm{systole})^n/\mathrm{volume}$. Its supremum on the set of all the riemannian metrics, is known to be finite for a large class of manifolds, including the $K(π,1)$. We study the optimal systo

Bernd Ammann, Mattias Dahl, Emmanuel Humbert

We prove a surgery formula for the smooth Yamabe invariant $σ(M)$ of a compact manifold $M$. Assume that $N$ is obtained from $M$ by surgery of codimension at least 3. We prove the existence of a positive number $Λ_n$, depending only on the dimension $n$ of $M$, such that $$ σ(N) \geq \min{σ(M),Λ_n}. $$

Joel K. Fridriksson, Jeroen Homan, Walter H. G. Lewin, Albert K. H. Kong

We analyze data from five Chandra observations of the spiral galaxy NGC 6946 and from three Chandra observations of the irregular/spiral interacting galaxy pair NGC 4485/4490, with an emphasis on investigating the long-term variability exhibited by the source populations. We detect 90 point sources coincident with NGC 6946 down to luminosities of a few times

Masanori Kyo, Tomohiro Harada, Hideki Maeda

We investigate self-similar solutions which are asymptotic to the Friedmann universe at spatial infinity and contain a scalar field with potential. The potential is required to be exponential by self-similarity. It is found that there are two distinct one-parameter families of asymptotic solutions,one is asymptotic to the proper Friedmann universe, while the

Ken-ichi Maruno, Yasuhiro Ohta

A new integrable (2+1)-dimensional nonlocal nonlinear Schrödinger equation is proposed. The $N$-soliton solution is given by Gram type determinant. It is found that the localized N-soliton solution has interesting interaction behavior which shows change of amplitude of localized pulses after collisions.

J. P. Lestone

If stimulated emission could be turned off then only uncorrelated photons would be emitted from black bodies and the photon counting statistics would be Poissonian. Through the process of stimulated emission, some fraction of the photons emitted from a black body are correlated and thus emitted in clusters. This photon clustering can be calculated by semi-cl

Mark M. Wilde, Todd A. Brun

We provide several formulas that determine the optimal number of entangled bits (ebits) that a general entanglement-assisted quantum code requires. Our first theorem gives a formula that applies to an arbitrary entanglement-assisted block code. Corollaries of this theorem give formulas that apply to a code imported from two classical binary block codes, to a

Oleg Titov

The motion of relativistic jets from the active extragalactic nuclei can reach several hundred microseconds per year and mimic proper motion of the distant radio sources observed by VLBI. Such motion of individual quasar is not correlated and its magnitude exceeds the small systematic effects induced by the rotation of the Solar system around the centre of t

Alexei Bazavov, Bernd A. Berg, Santosh Dubey

Using multicanonical Metropolis simulations we estimate phase transition properties of 3D Potts models for q=4 to 10: The transition temperatures, latent heats, entropy gaps, normalized entropies at the disordered and ordered endpoints, interfacial tensions, and spinodal endpoints.

Takashi Matsuoka

We compute the generalized Lefschetz number of orientation-preserving self-homeomorphisms of a compact punctured disk, using the fact that homotopy classes of these homeomorphisms can be identified with braids. This result is applied to study Nielsen-Thurston canonical homeomorphisms on a punctured disk. We determine, for a certain class of braids, the rotat

Ming-Hao Liu, Son-Hsien Chen, Ching-Ray Chang

The well-known experimentally observed \textit{sp}-derived Au(111) Shockley surface states with Rashba spin splitting are perfectly fit by an effective tight-binding model, considering a two-dimensional hexagonal lattice with $p_{z}$-orbital and nearest neighbor hopping only. The extracted realistic band parameters are then imported to perform the Landauer-K

Xinjia Chen

In this paper, we develop a general approach for probabilistic estimation and optimization. An explicit formula and a computational approach are established for controlling the reliability of probabilistic estimation based on a mixed criterion of absolute and relative errors. By employing the Chernoff-Hoeffding bound and the concept of sampling, the minimiza

Behtash Behin-Aein, Sayeef Salahuddin, Supriyo Datta

Power dissipation in switching devices is believed to be the single most important roadblock to the continued down scaling of electronic circuits. There is a lot of experimental effort at this time to implement switching circuits based on magnets and it is important to establish power requirements for such circuits and their dependence on various parameters.

Wei-Bing Zhang, Xiao-Bing Xiao, Wei-Yang Yu, Na Wang

Based on First-principles calculation, we have investigated electronic structure of a ZrCuSiAs structured superconductor LaNiPO. The density of states, band structures and Fermi surfaces have been given in detail. Our results indicate that the bonding of the La-O and Ni-P is strongly covalent whereas binding property between the LaO and NiP blocks is mostly

Xinjia Chen

In this paper, we develop an approach for optimizing the explicit binomial confidence interval recently derived by Chen et al. The optimization reduces conservativeness while guaranteeing prescribed coverage probability.

Xinjia Chen

In this paper, we develop an exact method for computing the minimum coverage probability of Wald interval for estimation of binomial parameters. Similar approach can be used for other type of confidence intervals.

Emmanuel Breuillard

We show a global adelic analog of the classical Margulis Lemma from hyperbolic geometry. We introduce a conjugation invariant normalized height $\hat{h}(F)$ of a finite set of matrices $F$ in $GL_{n}(\bar{\Bbb{Q}})$ which is the adelic analog of the minimal displacement on a symmetric space. We then show, making use of theorems of Bilu and Zhang on the equid

Yoshihiro Nishiyama

The low-lying spectrum of the three-dimensional Ising model is investigated numerically; we made use of an equivalence between the excitation gap and the reciprocal correlation length. In the broken-symmetry phase, the magnetic excitations are attractive, forming a bound state with an excitation gap m_2(<2m_1) (m_1: elementary excitation gap). It is expected

Belle Collaboration

We report a fully inclusive measurement of the flavor changing neutral current decay $B\to X_sγ$ in the energy range $1.7 \GeV\le E^\mathrm{c.m.s}_γ\le 2.8 \GeV$, covering 97% of the total spectrum, where c.m.s is the center of mass system. Using $605\ifb$ of data, we obtain in the rest frame of the $B$-meson ${\mathcal B}(B\to X_sγ: E^B_γ>1.7 \mathrm{GeV})=

C. Hess

Transport properties provide important information about the mobility, elastic and inelastic of scattering of excitations in solids. Heat transport is well understood for phonons and electrons, but little is known about heat transport by magnetic excitations. Very recently, large and unusual magnetic heat conductivities were discovered in low-dimensional qua

Stefanie Wachter

We present preliminary results from our archival Spitzer Space Telescope program aimed at characterizing the mid-IR properties of compact objects, both isolated and in binary systems, i.e. white dwarfs, X-ray binaries, cataclysmic variables, and magnetars. Most of these sources are too faint at mid-IR wavelengths to be observable from the ground, so this stu

R. D. Somma, S. Boixo, H. Barnum, E. Knill

We describe a quantum algorithm that solves combinatorial optimization problems by quantum simulation of a classical simulated annealing process. Our algorithm exploits quantum walks and the quantum Zeno effect induced by evolution randomization. It requires order $1/\sqrtδ$ steps to find an optimal solution with bounded error probability, where $δ$ is the m

Patrick B. Hall, Piotr M. Kowalski, Hugh C. Harris, Akshay Awal

We report the discovery of a nearby, old, halo white dwarf candidate from the Sloan Digital Sky Survey. SDSS J110217.48+411315.4 has a proper motion of 1.75 arcsec/year and redder optical colors than all other known featureless (type DC) white dwarfs. We present SDSS imaging and spectroscopy of this object, along with near-infrared photometry obtained at the

Paolo Ghiggini, Ko Honda

We explain the effect of applying a full Lutz twist along a pre-Lagrangian torus in a contact 3-manifold, on the contact invariant in Heegaard Floer homology with twisted coefficients.

A. G. Kozorezov, A. A. Golubov, J. K. Wigmore, D. Martin

In a superconductor with magnetic impurities, Kondo scattering results in the formation of localized states inside the superconducting gap. We show that inelastic electronic transitions involving quasiparticle scattering into and out of the localized states may result in significant changes in the non equilibrium properties of the superconductor. Using the m

Aneta Siemiginowska, Stephanie LaMassa, Thomas L. Aldcroft, Jill Bechtold

We present {\it Chandra} X-ray Observatory observations of Giga-Hertz Peaked Spectrum (GPS) and Compact Steep Spectrum (CSS) radio sources. The {\it Chandra} sample contains 13 quasars and 3 galaxies with measured 2-10 keV X-ray luminosity within $10^{42} - 10^{46}$ erg s$^{-1}$. We detect all of the sources, five of which are observed in X-ray for the first

J. -F. Gerbeau, T. Lelievre

We consider two-fluid flow problems in an Arbitrary Lagrangian Eulerian (ALE) framework. The purpose of this work is twofold. First, we address the problem of the moving contact line, namely the line common to the two fluids and the wall. Second, we perform a stability analysis in the energy norm for various numerical schemes, taking into account the gravity

Sergei Gukov, Edward Witten

Surface operators in gauge theory are analogous to Wilson and &#39;t Hooft line operators except that they are supported on a two-dimensional surface rather than a one-dimensional curve. In a previous paper, we constructed a certain class of half-BPS surface operators in N=4 super Yang-Mills theory, and determined how they transform under S-duality. Those su

Sofia Quaglioni, Petr Navratil

We develop a new ab initio many-body approach capable of describing simultaneously both bound and scattering states in light nuclei, by combining the resonating-group method with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters. This approach preserves translational symmetry and Pauli principle. We prese

Elvira Gamiz, Junko Shigemitsu, Howard Trottier

We present one-loop matching coefficients between continuum and lattice QCD for the heavy-light four-fermion operators relevant for neutral B meson mixing both within and beyond the Standard Model. For the lattice theory we use nonrelativistic QCD (NRQCD) to describe b quarks and improved staggered fermions (AsqTad) for light quarks. The gauge action is the

T. Senthil

We study theoretically the zero temperature phase transition in two dimensions from a Fermi liquid to a paramagnetic Mott insulator with a spinon Fermi surface. We show that the approach to the bandwidth controlled Mott transition from the metallic side is accompanied by a vanishing quasiparticle residue and a diverging effective mass. The Landau parameters

Gregory B. Poole, Arif Babul, Ian G. McCarthy, A. J. R. Sanderson

(Abridged) We use the simulations presented in Poole et al. 2006 to examine the effects of mergers on compact cool cores in X-ray clusters. We propose a scheme for classifying the morphology of clusters based on their surface brightness and entropy profiles. Three dominant morphologies emerge: two hosting compact cores and central temperatures which are cool

Marshall D. Perrin, James R. Graham, James P. Lloyd

We have upgraded IRCAL, the near-infrared science camera of the Lick Observatory adaptive optics system, to add a dual-channel imaging polarimetry mode. This mode uses an optically contacted YLF (LiYF_4) Wollaston prism to provide simultaneous images in perpendicular linear polarizations, providing high resolution, high dynamic range polarimetry in the near

Catarina Alves de Oliveira, Mark Casali

Variability is a common characteristic of pre-main-sequence stars (PMS). Near-IR variability surveys of young stellar objects (YSOs) can probe stellar and circumstellar environments and provide information about the dynamics of the on going magnetic and accretion processes. Furthermore, variability can be used as a tool to uncover new cluster members in star

D. Milisavljevic, R. Fesen, B. Leibundgut, R. Kirshner

We present late-time optical images and spectra of the Type IIn supernova SN 1986J. HST ACS/WFC images obtained in February 2003 show it to be still relatively bright with m(F606W) = 21.4 and m(F814W) = 20.0 mag. Compared against December 1994 HST WFPC2 images, SN 1986J shows a decline of only <1 mag in brightness over eight years. Ground-based spectra taken

Kaden R. A. Hazzard, Erich J. Mueller

We show that helium film-mediated hydrogen-hydrogen interactions account for a two orders of magnitude discrepancy between previous theory and recent experiments on cold collision shifts in spin-polarized hydrogen adsorbed on a helium film. These attractive interactions also explain the anomalous dependence of the cold collision frequency shifts on the $^3$H

Régis Guégan, Denis Morineau, Ronan Lefort, Wilfried Béziel

We present a neutron and X-rays scattering study of the phase transitions of 4-n-octyl-4&#39;-cyanobiphenyl (8CB) confined in unidirectional nanopores of porous alumina and porous silicon (PSi) membranes with an average diameter of 30 nm. Spatial confinement reveals a rich polymorphism, with at least four different low temperature phases in addition to the s

Rogerio de Sousa, Joel E. Moore

Logical devices based on spin waves offer the potential to avoid dissipation mechanisms that limit devices based on either the charge or spin of mobile electrons. Multiferroic magnetoelectrics, which are materials that combine ferroelectric and magnetic order, allow direct switching of magnetic order and thence of spin-wave properties using an applied electr

Nasser Metwally, Abdel-Shafy F. Obada

A new modified version of the Oxford purification protocol is proposed. This version is based on the controlled-controlled NOT gate instead of controlled NOT in the original one. Comparisons between the results of the new version and the original and an earlier modification are given. It is found that the new version converges faster and consumes fewer initi

Susumu Takahashi, Ronald Hanson, Johan van Tol, Mark S. Sherwin

We experimentally demonstrate that the decoherence of a spin by a spin bath can be completely eliminated by fully polarizing the spin bath. We use electron paramagnetic resonance at 240 gigahertz and 8 Tesla to study the spin coherence time $T_2$ of nitrogen-vacancy centers and nitrogen impurities in diamond from room temperature down to 1.3 K. A sharp incre

Vicent J. Martinez

The most popular tools for analysing the large scale distribution of galaxies are second-order spatial statistics such as the two-point correlation function or its Fourier transform, the power spectrum. In this review, we explain how our knowledge of cosmic structures, encapsulated by these statistical descriptors, has evolved since their first use when appl

Patrick Keith-Hynes, H. B. Thacker

The behavior of Wilson loops with fractional charge is used to study the $θ$-dependence of the free energy density $ε(θ)$ for the $CP^1$, $CP^5$, and $CP^9$ sigma models in two spacetime dimensions. The function $ε(θ)$ is extracted from the area law for a Wilson loop of charge $q=θ/2π$. For $CP^1$, $ε(θ)$ is smooth in the region $θ\approxπ$ and well-describe

C. López-Sanjuan, C. E. García-Dabó, M. Balcells

The determination of galaxy merger fraction of field galaxies using automatic morphological indices and photometric redshifts is affected by several biases if observational errors are not properly treated. Here, we correct these biases using maximum likelihood techniques. The method takes into account the observational errors to statistically recover the rea

Y. Jia, T. P. Gorringe, M. D. Hasinoff, M. A. Kovash

We report measurements of the $π^- p \to π^o n$ differential cross sections at six momenta (104-143 MeV/c) and four angles (0-40 deg) by detection of $γ$-ray pairs from $π^o \to γγ$ decays using the TRIUMF RMC spectrometer. This region exhibits a vanishing zero-degree cross section from destructive interference between s-- and p--waves, thus yielding special

K. Bucior, L. Yelash, K. Binder

As a generic model system of an asymmetric binary fluid mixture, hexadecane dissolved in carbon dioxide is considered, using a coarse-grained bead-spring model for the short polymer, and a simple spherical particle with Lennard-Jones interactions for the carbon dioxide molecules. In previous work, it has been shown that this model reproduces the real phase d

B. Aneva

A realization of a deformed Lorentz algebra is considered and its irreducible representations are found; in the limit $q\to 1$, these are precisely the irreducible representations of the classical Lorentz group.

Uli Heber

Hot subluminous stars can be roughly divided into B- and O-types. Unlike the latter many sdBs are found in close binaries, indicating that binary evolution plays a vital role. Recent NLTE spectral analyses revealed that an evolutionary link between sdB stars and sdO stars is plausible only for the helium-deficient sdO stars, i.e. they are the likely successo

Jianmin Tao, John P. Perdew, Luis Miguel Almeida, Carlos Fiolhais

Earlier tests show that the Tao-Perdew-Staroverov-Scuseria (TPSS) nonempirical meta-generalized gradient approximation (meta-GGA) for the exchange-correlation energy yields more accurate surface energies than the local spin density (LSD) approximation for spin-unpolarized jellium. In this study, work functions and surface energies of a jellium metal in the p

Shingo Yonezawa, Shuichi Kusaba, Yoshiteru Maeno, Pascale Auban-Senzier

We have studied the onset temperature of the superconductivity Tc_onset of the organic superconductor (TMTSF)2ClO4, by precisely controlling the direction of the magnetic field H. We compare the results of two samples with nearly the same onset temperature but with different scattering relaxation time tau. We revealed a complicated interplay of a variety of

Victor O. Rivelles

The Faddeev-Reshetikhin model arises as a truncation of strings in AdS_5XS^5. Its two particle S-matrix should be obtained by diagonalizing its Hamiltonian. However this does not happen in a straightforward way. There is a Lorentz violating term in the Hamiltonian which prevents its plain diagonalization. We then find out the most general quartic Hamiltonian

M. Hirsch, S. Morisi, J. W. F. Valle

We present a tri-bimaximal lepton mixing scheme where the neutrinoless double beta decay rate (bb0v) has a lower bound which correlates with the ratio alpha = Dmsol/Dmatm well determined by current data, as well as with the unknown Majorana CP phase phi12 characterizing the solar neutrino sub-system. For the special value phi12 = pi/2 (opposite CP-sign neutr

N. Christlieb, T. Schoerck, A. Frebel, T. C. Beers

We present the quantitative methods used for selecting candidate metal-poor stars in the Hamburg/ESO objective-prism survey (HES). The selection is based on the strength of the Ca II K line, B-V colors (both measured directly from the digital HES spectra), as well as J-K colors from the 2 Micron All Sky Survey. The KP index for Ca II K can be measured from t

Ivano Eligio Castelli, Nicola Manini, Rosario Capozza, Andrea Vanossi

Within the idealized scheme of a 1-dimensional Frenkel-Kontorova-like model, a special &#34;quantized&#34; sliding state was found for a solid lubricant confined between two periodic layers [PRL 97, 056101 (2006)]. This state, characterized by a nontrivial geometrically fixed ratio of the mean lubricant drift velocity <v_cm> and the externally imposed transl

Bhavya B, Blesson Mathew, Annapurni Subramaniam

The recent star formation history in the Cygnus region is studied using 5 clusters (IC 4996, NGC 6910, Berkeley 87, Biurakan 2 and Berkeley 86). The optical data from the literature are combined with the 2MASS data to identify the pre-main sequence (pre-MS) stars as stars with near IR excess. We identified 93 pre-MS stars and 9 stars with H$_α$ emission spec

Gao Xianlong, Marco Polini, Diego Rainis, M. P. Tosi

Motivated by the large interest in the non-equilibrium dynamics of low-dimensional quantum many-body systems, we present a fully-microscopic theoretical and numerical study of the &#34;charge&#34; and &#34;spin&#34; dynamics in a one-dimensional ultracold Fermi gas following a quench. Our approach, which is based on time-dependent current-density-functional

Cédric Weber, Kristjan Haule, Gabriel Kotliar

We use the Local Density Approximation in combination with the Dynamical Mean Field Theory to investigate intermediate energy properties of the copper oxides. We identify coherent and incoherent spectral features that results from doping a charge transfer insulator, namely quasiparticles, Zhang-Rice singlet band, and the upper and lower Hubbard bands. Angle

N. Barbosa-Cendejas, M. A. Reyes

Using the isospectral partners of the Bessel functions derived by Reyes et al., we find, on one hand, that these functions show non-typical supersymmetric (SUSY) behavior and, on the other, that the isospectral partner of the classical wave equation is equivalent to that of a damped system whose oscillations do not vanish in time, but show a non-harmonic sha

Christian Böhning

This article is a survey of P. Katsylo&#39;s proof that the moduli space of smooth projective complex curves of genus 3 is rational. We hope to make the argument more comprehensible and transparent by emphasizing the underlying geometry in the proof and its key structural features.

Michel Weber

We give several applications of an identity for sums of weakly stationary sequences due to Ky Fan.

S. K. Lamoreaux, R. Golub

The role of 3He-3He collisions in our diffusion experiment is addressed and shown to not be relevant to the measurement of 3He diffusion against phonons in superfluid helium.

J. -P. Luminet

In 2007 an international conference engaged a reflection on the present conditions for sciences and scientific practice, to initiate a dialogue between science, philosophy, epistemology and sociology. Starting from many examples taken from the history of sciences and the present status of astrophysics, cosmology and fundamental physics, I analyze various iss

Christian Böhning, Hans-Christian Graf v. Bothmer

We prove that the moduli space of plane curves of degree d is rational for all sufficiently large d.

Erasmo Recami

This writing has been prepared on the occasion of the 75th birthday of E.C.George Sudarshan, who (besides the originator of the V-A theory for weak-forces, of quantum optics --the quantum representation of coherent light--, of dynamical maps for open quantum systems, of the Zeno effect, etc.) was a pioneer, already in the sisties, also of the theory of the s

Christian Spiering

Astroparticle physics has evolved as an interdisciplinary field at the intersection of particle physics, astronomy and cosmology. Over the last two decades, it has moved from infancy to technological maturity and is now envisaging projects on the 100 Million Euro scale. This price tag requires international coordination, cooperation and convergence to a few

Blesson Mathew, Annapurni Subramaniam, Bhuwan Chandra Bhatt

Emission-line stars in young open clusters are identified to study their properties, as a function of age, spectral type and their evolutionary state. 207 open star clusters were observed using slitless spectroscopy method and 157 emission stars were identified in 42 clusters. We have found 54 new emission-line stars in 24 open clusters, out of which 19 clus

Gabriel Molina-Terriza

In this letter a general method for expanding paraxial beams into multipolar electromagnetic fields is presented. This method is applied to the expansion of paraxial modes with orbital angular momentum (OAM), showing how the paraxial OAM is related to the general angular momentum of an electromagnetic wave. This method can be extended to quasi-paraxial beams

Maya Badr, Jean-Claude Belfiore

In this work, we present a construction of a family of space-time block codes for a Multi-Access Amplify-and- Forward Relay channel with two users and a single half-duplex relay. It is assumed that there is no Channel Side Information at the transmitters and that they are not allowed to cooperate together. Using the Diversity Multiplexing Tradeoff as a tool

Francesca Matteucci

This paper contains the lectures I delivered during the 37th Saas-Fee Advanced Course in March 2007. It reviews all the main ingredients necessary to build galactic chemical evolution models with particular attention to the Milky Way and the dwarf spheroidals of the Local Group. Both analytical and numerical models are discussed. Model results are compared t

Jakub Zygadło

We show that the subgroup generated by locally finite polynomial automorphisms of k^n is normal in GA_n. Also, some properties of normal subgroups of GA_n containing all diagonal automorphisms are given.

Maya Badr, Jean-Claude Belfiore

In this work, the Multiple transmit antennas Multiple Access Channel is considered. A construction of a family of distributed space-time codes for this channel is proposed. No Channel Side Information at the transmitters is assumed and users are not allowed to cooperate together. It is shown that the proposed code achieves the Diversity Multiplexing Tradeoff

Min-Su Shin, Michael A. Strauss, Masamune Oguri, Naohisa Inada

We present the first result of a survey for strong galaxy-galaxy lenses in Sloan Digital Sky Survey (SDSS) images. SDSS J082728.70+223256.4 was selected as a lensing candidate using selection criteria based on the color and positions of objects in the SDSS photometric catalog. Follow-up imaging and spectroscopy showed this object to be a lensing system. The

L. Bravina, I. Arsene, J. Bleibel, M. Bleicher

Two microscopic models, UrQMD and QGSM, were employed to study the formation of locally equilibrated hot and dense nuclear matter in heavy-ion collisions at energies from 11.6 AGeV to 160 AGeV. Analysis was performed for the fixed central cubic cell of volume V = 125 fm**3 and for the expanding cell which followed the growth of the central area with uniforml

A. V. Larionov, L. E. Golub

Electron spin dynamics is investigated in n-i-n GaAs/AlGaAs coupled quantum wells. The electron spin dephasing time is measured as a function of an external electrical bias under resonant excitation of the 1sHH intrawell exciton using a time-resolved Kerr rotation technique. It is found a strong electron spin dephasing time anisotropy caused by an interferen

Dragoş-Victor Anghel, Dmitry Churochkin

We apply the model introduced in Phys. Rev. B 75, 064202 (2007), cond-mat/0610469, to calculate the anisotropy effect in the interaction of two level systems with phonons in disordered crystals. We particularize our calculations to cubic crystals and compare them with the available experimental data to extract the parameters of the model. With these paramete

Andrei V. Kanaev, Jean-Pierre Petitet, Luc Museur, Vladimir Marine

Effect of the femtosecond and nanosecond UV laser irradiation (below the ablation threshold) of graphite-like hexagonal boron nitride (hBN) has been studied. Experiments were carried out with the compacted powder under high vacuum at room temperature using excimer KrF laser (248 nm). In the nanosecond operation mode, the laser-induced fluorescence spectra ar

Codruta Stoica

The paper emphasizes the property of stability for skew-evolution semiflows on Banach spaces, defined by means of evolution semiflows and evolution cocycles and which generalize the concept introduced by us in a previous paper. There are presented several general characterizations of this asymptotic property out of which can be deduced well known results of

Marie-Line Chabanol

We compute the small-tau expansion up to the third order for the form factor of two glued quantum star graphs with Neumann boundary conditions, by taking into account only the most backscattering orbits. We thus show that the glueing has no effect if the number of glueing edges is negligible compared to the number of edges of the graph, whereas it has an eff

Philippe Delorme, Chris J. Willott, Thierry Forveille, Xavier Delfosse

We present the first results of a wide field survey for cool brown dwarfs with the MegaCam camera on the CFHT telescope, the Canada-France Brown Dwarf Survey, hereafter CFBDS. Our objectives are to find ultracool brown dwarfs and to constrain the field-brown dwarf mass function thanks to a larger sample of L and T dwarfs. We identify candidates in CFHT/MegaC

Dragoş-Victor Anghel

We show that fractional exclusion statistics is manifested in general in interacting systems and we discuss the conjecture recently introduced (J. Phys. A: Math. Theor. 40, F1013, 2007), according to which if in a thermodynamic system the mutual exclusion statistics parameters are not zero, then they have to be proportional to the dimension of the Hilbert sp

S. V. Godambe, R. C. Rannot, P. Chandra, K. K. Yadav

In this paper we report on the Markarian 501 results obtained during our TeV $γ$-ray observations from March 11 to May 12, 2005 and February 28 to May 7, 2006 for 112.5 hours with the TACTIC $γ$-ray telescope. During 2005 observations for 45.7 hours, the source was found to be in a low state and we have placed an upper limit of 4.62 $\times$ 10$^{-12}$ photo

Dmitry A. Mazurenko, Agung A. Nugroho, Thomas T. M. Palstra, Paul H. M. van Loosdrecht

YVO3 exhibits a well separated sequence of orbital and spin order transitions at 200 K and 116 K, followed by a combined spin-orbital reorientation at 77 K. It is shown that the spin order can be destroyed by a sufficiently strong optical pulse within less than 4 ps. In contrast, the orbital reordering transition from C-type to G-type orbital order is slower

Wojciech Chacholski, Wolfgang Pitsch, Jerome Scherer, Don Stanley

We show that H-spaces with finitely generated cohomology, as an algebra or as an algebra over the Steenrod algebra, have homotopy exponents at all primes. This provides a positive answer to a question of Stanley.

J. Haidenbauer, Ulf-G. Meißner, A. Sibirtsev

The near-threshold behavior of the ppbar invariant mass spectrum from the J/psi -> omega ppbar decay reported recently by the BES Collaboration is analyzed. Contrary to the statement made by the BES Collaboration itself our study demonstrates that there is indeed a noticeable enhancement in the ppbar invariant mass spectrum near threshold. Moreover, this enh

Martina Dobrincic, Eva Villaver, Martin A. Guerrero, Arturo Manchado

We present the kinematics of a sample of bipolar planetary nebulae (PNe) which cover a wide range of observed morphologies and collimation degrees, from bipolar PNe with a marked equatorial ring and wide lobes to highly collimated objects. We use an empirical model in order to derive the expansion velocity, collimation degree, and inclination angle of the PN

Ronald Blaak, Swen Lehmann, Christos N. Likos

We study the effect of chargeable monomers on the conformation of dendrimers of low generation by computer simulations, employing bare Coulomb interactions. The presence of the latter leads to an increase in size of the dendrimer due to a combined effect of electrostatic repulsion and the presence of counterions within the dendrimer, and also enhances a shel

Luis Alvarez-Gaume, Cesar Gomez, Agustin Sabio Vera, Alireza Tavanfar

We study the possible holographic connection between the Regge limit in QCD and critical gravitational collapse of a perfect fluid in higher dimensions. We begin by analyzing the problem of critical gravitational collapse of a perfect fluid in any number of dimensions and numerically compute the associated Choptuik exponent in d=5, 6 and 7 for a range of val

D. Hennig, L. Schimansky-Geier, P. Hänggi

The nonintegrable Hamiltonian dynamics of particles placed in a symmetric, spatially periodic potential and subjected to a periodically varying field is explored. Such systems can exhibit a rich diversity of unusual transport features. In particular, depending on the setting of the initial phase of the drive, the possibility of a giant transient directed tra