October 2008 arXiv papers — page 8

Subhashish Banerjee, V. Ravishankar, R. Srikanth

We analyze the dynamics of entanglement in a two-qubit system interacting with an initially squeezed thermal environment via a quantum nondemolition system-reservoir interaction, with the system and reservoir assumed to be initially separable. We compare and contrast the decoherence of the two-qubit system in the case where the qubits are mutually close-by (

Vigleik Angeltveit

We show that there is an essentially unique S-algebra structure on the Morava K-theory spectrum K(n), while K(n) has uncountably many MU or \hE{n}-algebra structures. Here \hE{n} is the K(n)-localized Johnson-Wilson spectrum. To prove this we set up a spectral sequence computing the homotopy groups of the moduli space of A-infinity structures on a spectrum,

Kiyotomo Ichiki, Masahiro Takada, Tomo Takahashi

The weak lensing (WL) distortions of distant galaxy images are sensitive to neutrino masses by probing the suppression effect on clustering strengths of total matter in large-scale structure. We use the latest measurement of WL correlations, the CFHTLS data, to explore constraints on neutrino masses. We find that, while the WL data alone cannot place a strin

Nobuhiro Uekusa

We investigate the Lagrangian terms of scalar-gauge interactions in a weakly-coupled gauge theory beyond the ultraviolet momentum cutoff of models where the collective symmetry breaking mechanism protects the Higgs mass squared against having quadratic divergence. We also propose a five-dimensional model in which the gauge symmetry breaking is achieved by bo

Rafael I. Nepomechie, Eric Ragoucy

We prove an inversion identity for the open AdS/CFT SU(1|1) quantum spin chain which is exact for finite size. We use this identity, together with an analytic ansatz, to determine the eigenvalues of the transfer matrix and the corresponding Bethe ansatz equations. We also solve the closed chain by algebraic Bethe ansatz.

Nicholas D. Alikakos, Giorgio Fusco

We consider the system Δu - W_u (u) = 0, for u: R^2 -> R^2, W: R^2 -> R, where W_u (u) is a smooth potential, symmetric with respect to the u_1, u_2 axes, possessing two global minima a^\pm := (\pma,0) and two connections e^\pm(x_1) connecting the minima. We prove that there exists an equivariant solution u(x_1, x_2) satisfying u(x_1, x_2) -> a^\pm, as x_1 -

S. V. Anathpindika

It has long been suggested that shocks might play an important role in altering the form of the interstellar medium (ISM). Shocks enhance gas density and sufficiently dense regions may become self gravitating. Potential star forming clouds within larger molecular clouds, move randomly at supersonic speeds. Depending on the precollision velocity, colliding mo

Jens Zamanian, Gert Brodin, Mattias Marklund

We consider a dusty plasma, in which the dust particles have a magnetic dipole moment. A Hall-MHD type of model, generalized to account for the intrinsic magnetization, is derived. The model is shown to be energy conserving, and the energy density and flux is derived. The general dispersion relation is then derived, and we show that kinetic Alfvén waves exhi

Dietmar Zeiler

Preliminary results on azimuthal asymmetries in leptoproduction of real photons on an unpolarized hydrogen target measured at the HERMES experiment are presented. The analysis of data taken with different beam charges and helicities allows for a simultaneous extraction of asymmetries originating from the interference term and the squared DVCS amplitude. Size

Kazunari Shima, Motomu Tsuda

We point out the possibility that the magnitude of the bare gauge coupling constant is determined theoretically in a composite model of all particles in SUSY theories. We show explicitly in two space-time dimensions that the NL/L SUSY relation (i.e., a SUSY compositeness condition for all particles) between N = 2 LSUSY QED and N = 2 NLSUSY determines the mag

Akihiro Nishiyama

We study non-equilibrium quantum dynamics of the single-component scalar field theory in 1+1 space-time dimensions on the basis of the Kadanoff-Baym equation including the next-to-leading-order (NLO) skeleton diagrams. As an extension of the non-relativistic case, we derive relativistic kinetic entropy at the first order in the gradient expansion of the Kada

A. Avgoustidis, I. Zavala

We propose a novel inflationary scenario in string theory in which the inflaton field is a 'Wilson line' degree of freedom in the worldvolume of a probe Dp-brane, in a warped flux compactification. Kinetic terms for Wilson line fields on the world volume of a D-brane take a nonstandard Dirac-Born-Infeld (DBI) form. Thus, we work in the framework of D

M. Varagnolo, E. Vasserot

Using the orbifold KZ connection we construct a functor from an affine parabolic category O of type A to the category O of a cyclotomic rational double affine Hecke algebra. We give several results concerning this functor.

Riccardo Argurio, François Dehouck, Laurent Houart

We study how the supersymmetry algebra copes with gravitational duality. As a playground, we consider a charged Taub-NUT solution of D=4, N=2 supergravity. We find explicitly its Killing spinors, and the projection they obey provides evidence that the dual magnetic momenta necessarily have to appear in the supersymmetry algebra. The existence of such a modif

T. Harada, A. Umeya, Y. Hirabayashi

We examine theoretically production of the neutron-rich $^{10}_Λ$Li hypernucleus by a double-charge exchange ($π^-$, $K^+$) reaction on a $^{10}$B target with distorted-wave impulse approximation calculations. The result shows that the magnitude and shape of the calculated spectrum at 1.20 GeV/c by a one-step mechanism $π^-p \to K^+ Σ^-$ via $Σ^-$ doorways c

Alexander Esterov

For a system of polynomial equations, whose coefficients depend on parameters, the Newton polyhedron of its discriminant is computed in terms of the Newton polyhedra of the coefficients. This leads to an explicit formula (involving mixed fiber polyhedra and Euler obstructions of toric varieties) in the unmixed case, suggests certain open questions in general

Albrecht Klemm, Piotr Sułkowski

We derive a family of matrix models which encode solutions to the Seiberg-Witten theory in 4 and 5 dimensions. Partition functions of these matrix models are equal to the corresponding Nekrasov partition functions, and their spectral curves are the Seiberg-Witten curves of the corresponding theories. In consequence of the geometric engineering, the 5-dimensi

O. Adriani, G. C. Barbarino, G. A. Bazilevskaya, R. Bellotti

A new measurement of the cosmic ray antiproton-to-proton flux ratio between 1 and 100 GeV is presented. The results were obtained with the PAMELA experiment, which was launched into low-earth orbit on-board the Resurs-DK1 satellite on June 15th 2006. During 500 days of data collection a total of about 1000 antiprotons have been identified, including 100 abov

Vincent Bansaye, Julien Berestycki

A branching process in random environment $(Z_n, n \in \N)$ is a generalization of Galton Watson processes where at each generation the reproduction law is picked randomly. In this paper we give several results which belong to the class of {\it large deviations}. By contrast to the Galton-Watson case, here random environments and the branching process can co

G. Cognola, E. Elizalde, S. D. Odintsov, P. Tretyakov

Viable models of modified gravity which satisfy both local as well as cosmological tests are investigated. It is demonstrated that some versions of such highly non-linear models exhibit multiply de Sitter universe solutions, which often appear in pairs, being one of them stable and the other unstable. It is explicitly shown that, for some values of the param

J. Vijande, A. Valcarce, F. Fernandez

Within a theoretical framework that accounts for all open-charm mesons, including the $D_0^*(2308)$, the $D_{sJ}^*(2317)$ and the $D_{sJ}(2460)$, we analyze the structure and explore possible quantum number assignments for the $D_{sJ}(2860)$ and the $D_{sJ}(2700)$ mesons reported by BABAR and Belle Collaborations. The open-charm sector is properly described

Baris Coskunuzer

We show that for a generic nullhomotopic simple closed curve C in the boundary of a compact, orientable, mean convex 3-manifold M with trivial second homology, there is a unique area minimizing disk D embedded in M where the boundary of D is C. We also show that the same is true for absolutely area minimizing surfaces.

S. Kettemann, E. R. Mucciolo, I. Varga

It is well-known that magnetic impurities can change the symmetry class of disordered metallic systems by breaking spin and time-reversal symmetry. At low temperature these symmetries can be restored by Kondo screening. It is also known that at the Anderson metal-insulator transition, wave functions develop multifractal fluctuations with power law correlatio

Kiel Howe, Aristeu R. P. Lima, Axel Pelster

Motivated by recent experiments on rotating Bose-Einstein condensates, we investigate a rotating, polarized Fermi gas trapped in an anharmonic potential. We apply a semiclassical expansion of the density of states in order to determine how the thermodynamic properties depend on the rotation frequency. The accuracy of the semiclassical approximation is tested

Yu Shi

We examine the practical feasibility of the experimental realization of the so-called entangled Bose-Einstein condensation (BEC), occurring in an entangled state of two atoms of different species. We demonstrate that if the energy gap remains vanishing, the entangled BEC persists as the ground state of the concerned model in a wide parameter regime. We estab

Jie-Yun Yan, Ping Zhang, Bo Sun, Hai-Zhou Lu

We investigate theoretically the electronic transport properties in narrow graphene ribbons with an adatom-induced defect. It is found that the lowest conductance step of a metallic graphene nanoribbon may develop a dip even down to zero at certain values of the Fermi energy due to the defect. Accompanying the occurrence of the conductance dip, a loop curren

Yong-Lu Liu, Ming-Qiu Huang, Dao-Wei Wang

We present the light-cone QCD sum rules up to twist 6 for the electromagnetic form factors of the $Λ$ baryon. To estimate the magnetic moment of the baryon, the magnetic form factor is fitted by the dipole formula. The numerical value of our estimation is $μ_Λ=-(0.64\pm0.04)μ_N$, which is in accordance with the experimental data and the existing theoretical

Yunping Jiang

We introduce a function model for the Teichm\"uller space of a closed hyperbolic Riemann surface. Then we introduce a new metric by using the maximum norm on the function space on the Teichm\"uller space. We prove that the identity map from the Teichm\"uller space equipped with the usual Teichm\"uller metric to the Teichm\"uller space equipped with this new

Yi-Kai Liu

The curvelet transform is a directional wavelet transform over R^n, which is used to analyze functions that have singularities along smooth surfaces (Candes and Donoho, 2002). I demonstrate how this can lead to new quantum algorithms. I give an efficient implementation of a quantum curvelet transform, together with two applications: a single-shot measurement

Tomoyuki Arakawa, Dmytro Chebotarov, Fyodor Malikov

We propose a notion of algebra of {\it twisted} chiral differential operators over algebraic manifolds with vanishing 1st Pontrjagin class. We show that such algebras possess families of modules depending on infinitely many complex parameters, which we classify in terms of the corresponding algebra of twisted differential operators. If the underlying manifol

Aaron A. Dutton, Frank C. van den Bosch

We use a disk galaxy evolution model to investigate the impact of mass outflows (a.k.a. feedback) on disk galaxy scaling relations. Our model follows the accretion, cooling, star formation and ejection of baryonic mass inside growing dark matter haloes, with cosmologically motivated specific angular momentum distributions. Models without feedback produce dis

Ki-Myeong Lee, Erick J. Weinberg

We explore the characteristics of spherical bags made of large numbers of BPS magnetic monopoles. There are two extreme limits. In the Abelian bag, $N$ zeros of the Higgs field are arranged in a quasiregular lattice on a sphere of radius $R_{\rm cr} \sim N/v$, where $v$ is the Higgs vacuum expectation value. The massive gauge fields of the theory are largely

John Dubinski, Ingo Berentzen, Isaac Shlosman

We examine the bar instability in galactic models with an exponential disk and a cuspy dark matter (DM) halo with a Navarro-Frenk-White (NFW) cosmological density profile. We construct equilibrium models from a 3-integral composite distribution function that are subject to the bar instability. We generate a sequence of models with a range of mass resolution

Q. E. Hoq

It is known that there are nonlinear wave equations with localized solitary wave solutions. Some of these solitary waves are stable (with respect to a small perturbation of initial data) and have nonzero spin (nonzero intrinsic angular momentum in the center of momentum frame). In this paper we consider vector-valued solitary wave solutions to a nonlinear Kl

Donald Marolf, Ian A. Morrison

Perturbative gravity about global de Sitter space is subject to linearization-stability constraints. Such constraints imply that quantum states of matter fields couple consistently to gravity {\it only} if the matter state has vanishing de Sitter charges; i.e., only if the state is invariant under the symmetries of de Sitter space. As noted by Higuchi, the u

Ana Júlia Mizher, Eduardo S. Fraga

We study the effects of CP violation on the nature of the chiral transition within the linear sigma model with two flavors of quarks. The finite-temperature effective potential containing contributions from nontrivial values for the parameter $θ$ is computed to one loop order and their minima structure is analyzed. Motivated by the possibility of observing t

Ron Lifshitz

After providing a concise overview on quasicrystals and their discovery more than a quarter of a century ago, I consider the unexpected interplay between nanotechnology and quasiperiodic crystals. Of particular relevance are efforts to fabricate artificial functional micro- or nanostructures, as well as efforts to control the self-assembly of nanostructures,

C. MacLeod, Z. Ivezic, W. de Vries, B. Sesar

Significant progress in the description of quasar variability has been recently made by employing SDSS and POSS data. Common to most studies is a fundamental assumption that photometric observations at two epochs for a large number of quasars will reveal the same statistical properties as well-sampled light curves for individual objects. We critically test t

Alec Pawling, Ping Yan, Julián Candia, Tim Schoenharl

In this chapter we consider a cell phone network as a set of automatically deployed sensors that records movement and interaction patterns of the population. We discuss methods for detecting anomalies in the streaming data produced by the cell phone network. We motivate this discussion by describing the Wireless Phone Based Emergency Response (WIPER) system,

Z. Ivezic, T. Axelrod, A. C. Becker

The Large Synoptic Survey Telescope (LSST) will be a large, wide-field ground-based system designed to obtain, starting in 2015, multiple images of the sky that is visible from Cerro Pachon in Northern Chile. About 90% of the observing time will be devoted to a deep-wide-fast survey mode which will observe a 20,000 deg$^2$ region about 1000 times during the

V. Suneeta

We briefly review studies of off-shell stability of vacuum geometries in semiclassical gravity. We propose a study of off-shell stability of vacua in string theory by a distinct, though somewhat related approach -- by studying their stability under suitable world-sheet sigma model renormalization group (RG) flows. Stability under RG flow is a mathematically

A. J. Daley, J. M. Taylor, S. Diehl, M. Baranov

We discuss how large three-body loss of atoms in an optical lattice can give rise to effective hard-core three-body interactions. For bosons, in addition to the usual atomic superfluid, a dimer superfluid can then be observed for attractive two-body interactions. The non-equilibrium dynamics of preparation and stability of these phases are studied in 1D by c

K. M. Schure, J. Vink, A. Achterberg, R. Keppens

Supernova remnants (SNR) are now widely believed to be a source of cosmic rays (CRs) up to an energy of 1 PeV. The magnetic fields required to accelerate CRs to sufficiently high energies need to be much higher than can result from compression of the circumstellar medium (CSM) by a factor 4, as is the case in strong shocks. Non-thermal synchrotron maps of th

Francesca Di Patti, Duccio Fanelli

A stochastic model is here introduced to investigate the molecular mechanisms which trigger the perception of pain. The action of analgesic drug compounds is discussed in a dynamical context, where the competition with inactive species is explicitly accounted for. Finite size effects inevitably perturb the mean-field dynamics: Oscillations in the amount of b

Jerome Le Ny, Eric Feron, Munther A. Dahleh

A set of N independent Gaussian linear time invariant systems is observed by M sensors whose task is to provide the best possible steady-state causal minimum mean square estimate of the state of the systems, in addition to minimizing a steady-state measurement cost. The sensors can switch between systems instantaneously, and there are additional resource con

Lei Zhang

We consider a sequence of blowup solutions of a two dimensional, second order elliptic equation with exponential nonlinearity and singular data. This equation has a rich background in physics and geometry. In a work of Bartolucci-Chen-Lin-Tarantello it is proved that the profile of the solutions differs from global solutions of a Liouville type equation only

C. C. Joggerst, S. E. Woosley, Alexander Heger

Two-dimensional simulations of mixing and fall back in non-rotating massive stars have been carried out using realistic initial models for the presupernova star and assuming standard spherically symmetric explosions of 1.2*10^51ergs. Stars of 15 and 25 solar masses with both primordial and solar composition were modeled. The zero metallicity supernova progen

Huey-Wen Lin, Saul D. Cohen, Robert G. Edwards, Kostas Orginos

There is an extensive history of form factor calculations on the lattice, primarily with ground states for both initial and final states. However, there have never been any radially excited transition form factor calculations. Furthermore, the lattice faces difficulty in extracting signal from noise at large transfer momenta ($Q^2$). These measurements could

Lei Zhang

We consider positive solutions of $Δu-μu+Ku^{\frac{n+2}{n-2}}=0$ on $B_1$ ($n\ge 5$) where $μ$ and $K>0$ are smooth functions on $B_1$. If $K$ is very sub-harmonic at each critical point of $K$ in $B_{2/3}$ and the maximum of $u$ in $\bar B_{1/3}$ is comparable to its maximum over $\bar B_1$, then all positive solutions are uniformly bounded on $\bar B_{1/3}

A. Reiners, G. Basri, M. Browning

We present magnetic flux measurements in seven rapidly rotating M dwarfs. Our sample stars have X-ray and H-alpha emission indicative of saturated emission, i.e., emission at a high level independent of rotation rate. Our measurements are made using near-infrared FeH molecular spectra observed with HIRES at Keck. Because of their large convective overturn ti

L. Kaltenegger, C. Eiroa, C. V. M. Fridlund

In order to evaluate and develop mission concepts for a search for Terrestrial Exoplanets, we have prepared a list of potential target systems. In this paper we present and discuss the criteria for selecting potential target stars suitable for the search for Earth like planets, with a special emphasis on the aspects of the habitable zone for these stellar sy

D. Rubi, C. de Graaf, C. J. M. Daumont, D. Mannix

Thin films of TbMnO3 have been grown on SrTiO3 substrates. The films grow under compressive strain and are only partially clamped to the substrate. This produces remarkable changes in the magnetic properties and, unlike the bulk material, the films display ferromagnetic interactions below the ordering temperature of ~40K. X-ray photoemission measurements in

Miguel F. Morales

This proceeding concentrates on the BAO signature of dark energy, and how the SKA dark energy case has been complicated by the emergence of HI structure experiments modeled after the Epoch of Reionization observatories. The purpose of the conference talk was to review the current status of the Murchison Widefield Array (MWA), and show the applications of HI

M. -H. Julien

In a recent NMR investigation of the iron-based superconductor (La0.87Ca0.13)FePO [Phys. Rev. Lett. 101, 077006 (2008)] Y. Nakai et al. reported an anomalous behavior of the nuclear spin-lattice relaxation of 31P nuclei in the superconducting state: The relaxation rate 1/T1 strongly depends on the measurement frequency and its T dependence does not show the

Philip Kaaret, Hua Feng, Mark Gorski

We detected a major X-ray outburst from M82 with a duration of 79 days, an average flux of 5E-11 erg cm^-2 s^-1 in the 2-10 keV band, and strong variability. The X-ray spectrum remained hard throughout the outburst. We obtained a Chandra observation during the outburst that shows that the emission arises from the ultraluminous X-ray source X41.4+60. This sou

Alessandro Melchiorri, Olga Mena, Sergio Palomares-Ruiz, Silvia Pascoli

Light sterile neutrinos might mix with the active ones and be copiously produced in the early Universe. In the present paper, a detailed multi-flavor analysis of sterile neutrino production is performed. Making some justified approximations allows us to consider not only neutrino interactions with the primeval medium and neutrino coherence breaking effects,

Janice C. Lee, Robert C. Kennicutt, José G. Funes S. J., Shoko Sakai

An unresolved question in galaxy evolution is whether the star formation histories of low mass systems are preferentially dominated by starbursts or modes that are more quiescent and continuous. Here, we quantify the prevalence of global starbursts in dwarf galaxies at the present epoch, and infer their characteristic durations and amplitudes. The analysis i

Eric D. Miller, Joel N. Bregman, Bart P. Wakker

We present deep HI 21-cm and optical observations of the face-on spiral galaxy M 83 obtained as part of a project to search for high-velocity clouds (HVCs) in nearby galaxies. Anomalous-velocity neutral gas is detected toward M 83, with 5.6x10^7 Msolar of HI contained in a disk rotating 40-50 km/s more slowly in projection than the bulk of the gas. We interp

J. E. Hirsch

Superconductivity occurs in systems that have a lot of negative charge: the highly negatively charged $(CuO2)^{--}$ planes in the cuprates, negatively charged $(FeAs)^-$ planes in the iron arsenides, and negatively charged $B^-$ planes in magnesium diboride. And, in the nearly filled (with negative electrons) bands of almost all superconductors, as evidenced

M. Kirchbach, C. Compean

Non-perturbative methods of effective field theory such like Lattice QCD have allowed to establish connection between the QCD Lagrangian and quark potential models, a prominent outcome being the Cornell (linear plus Coulomb) potential. In being quite successful in explaining properties of heavy flavor hadrons, be them quarkonia or baryons, this potential has

Ying Ran, Yi Zhang, Ashvin Vishwanath

Topological defects, such as domain walls and vortices, have long fascinated physicists. A novel twist is added in quantum systems like the B-phase of superfluid helium He$_3$, where vortices are associated with low energy excitations in the cores. Similarly, cosmic strings may be tied to propagating fermion modes. Can analogous phenomena occur in crystallin

Guillermo Torres, Claud H. Sandberg Lacy

We present new V-band differential photometry and radial-velocity measurements of the unevolved 1.18-day period F+G-type double-lined eclipsing binary VZ Cep. We determine accurate values for the absolute masses, radii, and effective temperatures as follows: M(A) = 1.402 +/- 0.015 M(Sun), R(A) = 1.534 +/- 0.012 R(Sun), T(eff) = 6690 +/- 160 K for the primary

Martin Bojowald, Juan D. Reyes

Spherically symmetric gravity in Ashtekar variables coupled to Yang-Mills theory in two dimensions and its relation to dilaton gravity and Poisson sigma models are discussed. After introducing its loop quantization, quantum corrections for inverse triad components are shown to provide a consistent deformation without anomalies. The relation to Poisson sigma

Rachel Kuzio de Naray, Stacy S. McGaugh, J. Christopher Mihos

We model the NFW potential to determine if, and under what conditions, the NFW halo appears consistent with the observed velocity fields of low surface brightness (LSB) galaxies. We present mock DensePak IFU velocity fields and rotation curves of axisymmetric and non-axisymmetric potentials that are well-matched to the spatial resolution and velocity range o

Anil Raj, Chris H. Wiggins

In this report, we derive a non-negative series expansion for the Jensen-Shannon divergence (JSD) between two probability distributions. This series expansion is shown to be useful for numerical calculations of the JSD, when the probability distributions are nearly equal, and for which, consequently, small numerical errors dominate evaluation.

Jr-Shin Li

In this article, we investigate the problem of simultaneously steering an uncountable family of finite dimensional time-varying linear systems. We call this class of control problems Ensemble Control, a notion coming from the study of spin dynamics in Nuclear Magnetic Resonance (NMR) spectroscopy and imaging (MRI). This subject involves controlling a continu

G. Giusi, G. Iannaccone, U. Ravaioli

In this paper we investigate "Warm Electron Injection" as a mechanism for NOR programming of double-gate SONOS memories through 2D full band Monte Carlo simulations. Warm electron injection is characterized by an applied VDS smaller than 3.15 V, so that electrons cannot easily accumulate a kinetic energy larger than the height of the Si/SiO2 barrier.

Xiao-Liang Qi, Shou-Cheng Zhang

We propose several novel physical phenomena based on nano-scale helical wires. Applying a static electric field transverse to the helical wire induces a metal to insulator transition, with the band gap determined by the applied voltage. Similar idea can be applied to "geometrically" constructing one-dimensional systems with arbitrary external potenti

Elizabeth J. Kupin, Debbie S. Yuster

We give several modifications of the Goulden-Jackson Cluster method for finding generating functions for words avoiding a given set of forbidden words. Our modifications include functions which can take into account various 'weights' on words, including single letter probability distributions, double letter (i.e. pairwise) probability distributions,

Vladimir Chekelian

Measurements of the longitudinal structure function FL at the ep collider HERA are presented. They are derived from inclusive deep inelastic neutral current e+p scattering cross section measurements based on data collected in 2007 with the H1 and ZEUS detectors at a positron beam energy of 27.5 GeV and proton beam energies of 920, 575 and 460 GeV. Employing

Carlos I. Mendoza, Ivan Santamaria-Holek

We propose a simple and general model accounting for the dependence of the viscosity of a hard sphere suspension at arbitrary volume fractions. The model constitutes a continuum-medium description based on a recursive-differential method that assumes a hierarchy of relaxation times. Geometrical information of the system is introduced through an effective vol

Jonathan Irwin, Suzanne Aigrain, Jerome Bouvier, Leslie Hebb

We report on the results of a time-series photometric survey of M50 (NGC 2323), a ~130 Myr open cluster, carried out using the CTIO 4m Blanco telescope and Mosaic-II detector as part of the Monitor project. Rotation periods were derived for 812 candidate cluster members over the mass range 0.2 <~ M/Msol <~ 1.1. The rotation period distributions show a clear

Miguel F. Morales, Michael Matejek

Next generation radio observatories such as the MWA, LWA, LOFAR, CARMA and SKA provide a number of challenges for interferometric data analysis. These challenges include heterogeneous arrays, direction-dependent instrumental gain, and refractive and scintillating atmospheric conditions. From the analysis perspective, this means that calibration solutions can

Oliver Krause, Masaomi Tanaka, Tomonori Usuda, Takashi Hattori

Type Ia supernovae (SNe Ia) are thermonuclear explosions of white dwarf stars in close binary systems. They play an important role as cosmological distance indicators and have led to the discovery of the accelerated expansion of the Universe. Among the most important unsolved questions are how the explosion actually proceeds and whether accretion occurs from

Simon Kors

This is a summary of arXiv:0806.3458, where the low energy effective theory of type IIA AdS_4 N=1 flux compactifications on nilmanifolds and cosets has been analyzed. We compute the superpotential, the Kähler potential and the mass spectrum for the light moduli. For the nilmanifold examples we perform a cross-check on the result for the mass spectrum by calc

Thomas D. Cohen, Elizabeth S. Werbos

The response of the QCD vacuum to very large static external magnetic fields (q B >> Lambda_QCD^2) is studied. In this regime, the magnetization of the QCD vacuum is naturally described via perturbative QCD. Combining pQCD and the Schwinger proper time formalism, we calculate the magnetization of the QCD vacuum due to a strong magnetic field at leading order

A. Elyiv, O. Melnyk, I. Vavilova

Geometric method based on the high-order 3D Voronoi tessellation is proposed for identifying the single galaxies, pairs and triplets. This approach allows to select small galaxy groups and isolated galaxies in different environment and find the isolated systems. The volume-limited sample of galaxies from the SDSS DR5 spectroscopic survey was used. We conclud

Ozgur Oyman

We consider a linear multi-hop network composed of multi-state discrete-time memoryless channels over each hop, with orthogonal time-sharing across hops under a half-duplex relaying protocol. We analyze the probability of error and associated reliability function \cite{Gallager68} over the multi-hop network; with emphasis on random coding and sphere packing

Zhen-Qing Chen, Masatoshi Fukushima

Let $D$ be an unbounded domain in $\RR^d$ with $d\geq 3$. We show that if $D$ contains an unbounded uniform domain, then the symmetric reflecting Brownian motion (RBM) on $\overline D$ is transient. Next assume that RBM $X$ on $\overline D$ is transient and let $Y$ be its time change by Revuz measure ${\bf 1}_D(x) m(x)dx$ for a strictly positive continuous i

F. Rahoui, S. Chaty, P. O. Lagage

We report mid-infrared observations of SGR 1806-20 and its environment - with the highest spatial resolution in this domain to date - using ESO/VISIR in 2005 and 2006, and we retrieved Spitzer/IRAC-MIPS archival data of the same field. We aimed at studying the mid-infrared emission of the stars associated with the same cluster as SGR 1806-20, to detect varia

F. Weber, A. Kreyssig, L. Pintschovius, R. Heid

We show that the superconducting energy gap $Δ$ can be directly observed in phonon spectra, as predicted by recent theories. In addition, since each phonon probes the gap on only a small part of the Fermi surface, the gap anisotropy can be studied in detail. Our neutron scattering investigation of the anisotropic conventional superconductor YNi$_2$B$_2$C dem

K. Karami

Here the effect of rotation up to third order in the angular velocity of a star on the p, f and g modes is investigated. To do this, the third-order perturbation formalism presented by Soufi et al. (1998) and revised by Karami (2008), was used. I quantify by numerical calculations the effect of rotation on the oscillation frequencies of a uniformly rotating

Ozgur Oyman, Moe Z. Win

The goal of this paper is to understand the key merits of multihop relaying techniques jointly in terms of their energy efficiency and spectral efficiency advantages in the presence of multiuser diversity gains from opportunistic (i.e., channel-aware) scheduling and identify the regimes and conditions in which relay-assisted multiuser communication provides

Miguel Pereira-Santaella, Almudena Alonso-Herrero, George H. Rieke, Luis Colina

We present results of our program Spitzer/IRS Mapping of local Luminous Infrared Galaxies (LIRGs). The maps cover the central 20&#34;x20&#34; or 30&#34;x 30&#34; regions of the galaxies, and use all four IRS modules to cover the full 5-38 microns spectral range. We have built spectral maps of the main mid-IR emission lines, continuum and PAH features, and ex

R. Smith, L. J. Churcher, M. C. Wyatt, M. M. Moerchen

60% of the A star members of the 12 Myr old beta Pictoris moving group (BPMG) show significant excess emission in the mid-infrared, several million years after the proto-planetary disk is thought to disperse. Theoretical models suggest this peak may coincide with the formation of Pluto-sized planetesimals in the disk, stirring smaller bodies into collisional

G. Chabrier, I. Baraffe, J. Leconte, J. Gallardo

In this review, we summarize our present knowledge of the behaviour of the mass-radius relationship from solar-type stars down to terrestrial planets, across the regime of substellar objects, brown dwarfs and giant planets. Particular attention is paid to the identification of the main physical properties or mechanisms responsible for this behaviour. Indeed,

A. L. Wysocki, J. K. Glasbrenner, K. D. Belashchenko

Thermodynamics of itinerant magnets is studied using a classical model with one parameter characterizing the degree of itinerancy. Monte Carlo simulations for bcc and fcc lattices are compared with the mean-field approximation and with the Onsager cavity field approximation extended to itinerant systems. The qualitative features of thermodynamics are similar

G. Beuf, C. Royon, D. Salek

The scaling properties at low $x$ of the proton DIS cross section and its charm component are analyzed with the help of the quality factor method. Scaling properties are tested both in the deep inelastic scattering data and in the structure functions reconstructed from CTEQ, MRST and GRV parametrisations of parton density functions. The results for DIS cross

J. Bellazzini, V. Benci, C. Bonanno, E. Sinibaldi

Roughly speaking a solitary wave is a solution of a field equation whose energy travels as a localised packet and which preserves this localisation in time. A soliton is a solitary wave which exhibits some strong form of stability so that it has a particle-like behaviour. In this paper we show a new mechanism which might produce solitary waves and solitons f

Emiliano Ippoliti

The paper analizes a set of issues related to analogy and analogical reasoning, namely: 1) The problem of analogy and its duplicity; 2) The role of analogy in demonstrative reasoning; 3) The role of analogy in non-demonstrative reasoning; 4) The limits of analogy; 5) The convergence, particularly in multiple analogical reasoning, of these two apparently dist

H. N. Mhaskar, F. J. Narcowich, J. Prestin, J. D. Ward

The purpose of this paper is to establish L^p error estimates, a Bernstein inequality, and inverse theorems for approximation by a space comprising spherical basis functions located at scattered sites on the unit n-sphere. In particular, the Bernstein inequality estimates L^p Bessel-potential Sobolev norms of functions in this space in terms of the minimal s

Stanislav Boldyrev, Don Huynh, Vladimir Pariev

We report experimental observation of an instability in a Couette-Taylor flow of a polymer fluid in a thin gap between two coaxially rotating cylinders in a regime where their angular velocity decreases with the radius while the specific angular momentum increases with the radius. In the considered regime, neither the inertial Rayleigh instability nor the pu

Deidre A. Hunter

I address the issue of dust and gas as seeds for metal-poor star formation by reviewing what we know about star formation in nearby dwarf galaxies and its relationship to the gas and dust. I (try to) speculate on the extent to which processes in nearby galaxies mimic star formation in the early universe.

Sally Dawson, C. B. Jackson

We compute the leading chiral-logarithmic corrections to the S parameter in the four-site Higgsless model. In addition to the usual electroweak gauge bosons of the Standard Model, this model contains two sets of heavy charged and neutral gauge bosons. In the continuum limit, the latter gauge bosons can be identified with the first excited Kaluza-Klein states

M. Iskin, C. J. Williams

We use the Bogoliubov-de Gennes formalism to analyze the ground state phases of harmonically trapped two-species fermion mixtures with unequal masses. In the weakly attracting limit and around unitarity, we find that the superfluid order parameter is spatially modulated around the trap center, and that its global maximum occurs at a finite distance away from

Travis Gagie

We show how to build an alphabetic minimax tree for a sequence (W = w_1, >..., w_n) of real weights in (O (n d \log \log n)) time, where $d$ is the number of distinct integers (\lceil w_i \rceil). We apply this algorithm to building an alphabetic prefix code given a sample.

J. F. Helmboldt, R. A. M. Walterbos, G. D. Bothun, K. O&#39;Neil

Using B, R, and H-alpha images of roughly equal-sized samples of low surface brightness (LSB) and high surface brightness (HSB) galaxies (~40 galaxies apiece), we have explored the dependence of HII region properties on local and global disc surface brightness. We have done this by constructing co-added HII region luminosity functions (LFs) according to loca

A. Denning, A. Booth, S. Lee, M. Ammonson

We present measurements of the velocity distribution of calcium atoms in an atomic beam generated using a dual-stage laser back-ablation apparatus. Distributions are measured using a velocity selective Doppler time-of-flight technique. They are Boltzmann-like with rms velocities corresponding to temperatures above the melting point for calcium. Contrary to a

Raffaele Punzi, Mattias N. R. Wohlfarth

We reconsider both the global and local stability of solutions of continuously evolving dynamical systems from a geometric perspective. We clarify that an unambiguous definition of stability generally requires the choice of additional geometric structure that is not intrinsic to the dynamical system itself. While global Lyapunov stability is based on the cho

K. Henneberger

The nonequilibrium photon Green function for a bounded medium surrounded by vacuum is analyzed on the basis of the Dyson equation. As its components, the field-field fluctuations as well as the spectral function split up into parts related to medium and vacuum. Particularly, it is shown that the vacuum-induced fluctuations describe propagation of arbitrary,