December 2006 arXiv papers — page 40

K. S. D. Beach, Anders W. Sandvik

We report on a valence bond projector Monte Carlo simulation of the cubic lattice quantum Heisenberg model with additional higher-order exchange interactions in each unit cell. The model supports two different valence bond solid ground states. In one of these states, the dimer pattern is a three-dimensional analogue of the columnar pattern familiar from two

H. -W. Hammer

Physical systems with a large scattering length have universal properties independent of the details of the interaction at short distances. Such systems can be realized in experiments with cold atoms close to a Feshbach resonance. They also occur in many other areas of physics such as nuclear and particle physics. The universal properties include a geometric

Eric Braaten, H. -W. Hammer

Atoms with a large scattering length have universal low-energy properties that do not depend on the details of their structure or their interactions at short distances. In the 2-atom sector, the universal properties are familiar and depend only on the scattering length. In the 3-atom sector for identical bosons, the universal properties include the existence

K. J. Alvine, O. G. Shpyrko, P. S. Pershan, K. Shin

The filling behavior of a room temperature solvent, perfluoromethylcyclohexane, in approximately 20 nm nanoporous alumina membranes was investigated in situ with small angle x-ray scattering. Adsorption in the pores was controlled reversibly by varying the chemical potential between the sample and a liquid reservoir via a thermal offset, $Δ$T. The system exh

Clément Faugeras, Gérard Martinez, A. Riedel, Rudolf Hey

Experimental results on the absolute magneto-transmission of a series of high density, high mobility GaAs quantum wells are compared with the predictions of a recent magnetoplasmon theory for values of the filling factor above 2. We show that the magnetoplasmon picture can explain the non-linear features observed in the magnetic field evolution of the cyclot

I. Carusotto, S. X. Hu, L. A. Collins, A. Smerzi

We study the density modulation that appears in a Bose-Einstein condensate flowing with supersonic velocity against an obstacle. The experimental density profiles observed at JILA are reproduced by a numerical integration of the Gross-Pitaevskii equation and then interpreted in terms of Cerenkov emission of Bogoliubov excitations by the defect. The phonon an

Zhi-Pan Li, Casey W. Miller, Igor V. Roshchin, Ivan K. Schuller

The dependence of thermally induced spontaneous magnetization reversal on time-dependent cooling protocols was studied. Slower cooling and longer waiting close to the Nèel temperature of the antiferromagnet ($T_N$) enhances the magnetization reversal. Cycling the temperature around $T_N$ leads to a thermal training effect under which the reversal magnitude i

Pierre Jop, Yoël Forterre, Olivier Pouliquen

A continuum description of granular flows would be of considerable help in predicting natural geophysical hazards or in designing industrial processes. However, the constitutive equations for dry granular flows, which govern how the material moves under shear, are still a matter of debate. One difficulty is that grains can behave like a solid (in a sand pile

T. Jeong, T. Jarlborg

The properties of Cu$_{x}$TiSe$_{2}$ are studied by band structure calculation based on the density functional theory for supercells. The density-of-states (DOS) for $x$=0 has a sharply raising shoulder in the neighborhood of the Fermi energy, $E_F$, which can be favorable for spacial charge modulations. The Cu impurity adds electrons and brings the DOS shou

Sébastien Aumaître, Angel Alastuey, Stephan Fauve

Using simple scaling arguments and two-dimensional numerical simulations of a granular gas excited by vibrating one of the container boundaries, we study a double limit of small $1-r$ and large $L$, where $r$ is the restitution coefficient and $L$ the size of the container. We show that if the particle density $n_0$ and $(1-r^2)(n_0 Ld)$ where $d$ is the par

E. Cappelluti, C. Grimaldi, F. Marsiglio

Strong spin-orbit coupling can have a profound effect on the electronic structure in a metal or semiconductor, particularly for low electron concentrations. We show how, for small values of the Fermi energy compared to the spin-orbit splitting of Rashba type, a topological change of the Fermi surface leads to an effective reduction of the dimensionality in t

C. S. Lue, C. N. Kuo, T. H. Su, G. J. Redhammer

We report the results of a $^{45}$Sc nuclear magnetic resonance (NMR) study on the quasi-one-dimensional compound Cu$_2$Sc$_2$Ge$_4$O$_{13}$ at temperatures between 4 and 300 K. This material has been a subject of current interest due to indications of spin gap behavior. The temperature-dependent NMR shift exhibits a character of low-dimensional magnetism wi

Denis J. Evans, Debra J. Searles

Recently there has been considerable interest in the Fluctuation Theorem (FT). The FT shows how time reversible microscopic dynamics leads to irreversible macroscopic behavior as the system size or observation time increases. We show that the argument of the Evans-Searles FT, the dissipation function, plays a central role in nonlinear response theory and der

Beata J. Dabrowska-Wuester, Elena A. Ostrovskaya, Tristram J. Alexander, Yuri S. Kivshar

We model the nonlinear behaviour of spin-1 Bose-Einstein condensates (BECs) with repulsive spin-independent interactions and either ferromagnetic or anti-ferromagnetic (polar) spin-dependent interactions, loaded into a one-dimensional optical lattice potential. We show that both types of BECs exhibit dynamical instabilities and may form spatially localized m

Chih-Chun Chien, Qijin Chen, Yan He, K. Levin

We present phase diagrams for population imbalanced, trapped Fermi superfluids near unitarity. In addition to providing quantitative values for the superfluid transition temperature, the pairing onset temperature and the transition line (separating the Sarma and phase separation regimes), we study experimental signatures of these transitions based on density

Seung-Yeop Lee

We calculate the boundary correlation function of fixed-to-free boundary condition changing operators in the square-lattice Ising model. The correlation function is expressed in four different ways using $2\times2$ block Toeplitz determinants. We show that these can be transformed into a scalar Toeplitz determinant when the size of the matrix is even. To kno

Julia S. Meyer, K. A. Matveev, A. I. Larkin

Upon increasing the electron density in a quantum wire, the one-dimensional electron system undergoes a transition to a quasi-one-dimensional state. In the absence of interactions between electrons, this corresponds to filling up the second subband of transverse quantization, and there are two gapless excitation modes above the transition. On the other hand,

E. Majernikova, Serge Shpyrko

We studied complex spectra of a two-level electron system coupled to two phonon (vibron) modes represented by the E$\otimes$e Jahn-Teller model. For particular rotation quantum numbers we found a coexistence of up to three regions of the spectra, (i) the dimerized region of long-range ordered (extended) pairs of oscillating levels, (ii) the short-range-order

B. Scott Gaudi

The yields from transit surveys can be used to constrain the frequency and statistical properties of extrasolar planets. Conversely, planet frequencies can be used to estimate expected detection rates, which are critical for the planning and execution of these surveys. Here I review efforts to accomplish these two related goals, both of which generally requi

Gelys Trancho, Nate Bastian, Francois Schweizer, Bryan W. Miller

We present Gemini optical spectroscopy of three young star clusters in the western tidal tail of NGC3256. Compact star clusters (as opposed to dwarf-galaxy candidates) in tidal tails are rare, with these three clusters the first for which detailed quantitative spectroscopy has ever been obtained. We find that two of these clusters appear to be coeval, while

M. Zhao, J. D. Monnier, G. Torres, A. F. Boden

Lambda Virginis (LamVir) is a well-known double-lined spectroscopic Am binary with the interesting property that both stars are very similar in abundance but one is sharp-lined and the other is broad-lined. We present combined interferometric and spectroscopic studies of LamVir. The small scale of the LamVir orbit (~20 mas) is well resolved by the Infrared O

J. M. C. Grave, M. S. N. Kumar

Aims: We test the technique of spectro-astrometry as a potential method to investigate the close environment of massive young stars. Method: Archival VLT near infrared K band spectra (R=8900) of three massive young stellar objects and one Wolf-Rayet star are examined for spectro-astrometric signatures. The young stellar objects display emission lines such as

F. Weber, R. Negreiros, P. Rosenfield, Andreu Torres i Cuadrat

There has been much recent progress in our understanding of quark matter, culminating in the discovery that if such matter exists in the cores of neutron stars it ought to be in a color superconducting state. This paper explores the impact of superconducting quark matter on the properties (e.g., masses, radii, surface gravity, photon emission) of compact sta

V. Casasola, L. Piovan, G. Galletta, D. Bettoni

We collected data for two samples of normal and interacting galaxies for a total of 2953 galaxies having fluxes in one or more of the following wavebands: FIR, 21 cm line, CO(1-0) lines and soft X-ray. The large set of data obtained allowed us to revisit some of the already known relations between the different tracers of the interstellar medium (ISM), such

Y. Ascasibar

In the current paradigm of cosmic structure formation, dark matter plays a key role on the formation and evolution of galaxies through its gravitational influence. On microscopic scales, dark matter particles are expected to annihilate amongst themselves into different products, with some fraction of the energy being transferred to the baryonic component. It

J. E. Dale, I. A. Bonnell, A. P. Whitworth

We conduct Smoothed Particle Hydrodynamics simulations of the `collect and collapse' scenario (Elmegreen and Lada, 1977) for star formation triggered by an expanding HII region. We simulate the evolution of a spherical uniform molecular cloud with an ionising source at its centre. The gas in the cloud is self-gravitating, although the cloud is prevented

K. A. Pounds, K. L. Page, J. N. Reeves

The narrow line QSO PG1211+143 has been a focus of recent attempts to understand the soft excess in AGN, while the 2001 XMM-Newton observation of this luminous AGN also provided evidence for a massive and energetic outflow. Here we consider a physical link between the energetic outflow and the variable soft excess.

J. Alves, M. Lombardi, C. Lada

Context: Stars form in the cold dense cores of interstellar molecular clouds and the detailed knowledge of the spectrum of masses of such cores is clearly a key for the understanding of the origin of the IMF. To date, observations have presented somewhat contradictory evidence relating to this issue. Aims: In this paper we propose to derive the mass function

L. Sbordone, P. Bonifacio, R. Buonanno, G. Marconi

The Sagittarius dwarf Spheroidal galaxy is the nearest neighbor of the Milky Way. Moving along a short period quasi-polar orbit within the Halo, it is being destroyed by the tidal interaction with our Galaxy, losing its stellar content along a huge stellar stream. We study the detailed chemical composition of 12 giant stars in the Sagittarius dwarf Spheroida

Thomas Wiegelmann

We describe a newly developed code for the extrapolation of nonlinear force-free coronal magnetic fields in spherical coordinates. The program uses measured vector magnetograms on the solar photosphere as input and solves the force-free equations in the solar corona. The method is based on an optimization principle and the heritage of the newly developed cod

S. Aalto, M. Spaans, M. C. Wiedner, S. Huttemeister

We find that the HNC J=3-2 emission is brighter than the HCN 3-2 emission by factors of 1.5 to 2.3 in the ultraluminous mergers Arp220 and Mrk231 and the luminous IR galaxy NGC4418. We furthermore report the detection of HNC J=4-3 in Mrk231. Overluminous HNC emission is unexpected in warm molecular gas in ultraluminous galaxies since I(HNC)>I(HCN) is usually

Guido Chincarini, Alberto Moretti, Patrizia Romano, Sergio Campana

The detection of flares with the Swift satellite triggered a lot of bservational and theoretical interest in these phenomena. As a consequence a large analysis effort started within the community to characterize the phenomenon and at the same time a variety of theoretical speculations have been proposed to explain it. In this presentation we discuss part of

O. Cucciati, A. Iovino, C. Marinoni, O. Ilbert

We investigate the redshift and luminosity evolution of the galaxy colour-density relation using the data from the First Epoch VIMOS-VLT Deep Survey (VVDS) on scales of R=5 h^(-1)Mpc up to redshift z ~ 1.5. While at lower redshift we confirm the existence of a steep colour-density relation, with the fraction of the reddest(/bluest) galaxies of the same lumin

C. Carretero, A. Vazdekis, J. E. Beckman, .

We present a detailed stellar population analysis of 27 massive elliptical galaxies within 4 very rich clusters at redshift z~0.2: A115, A655, A963 and A2111. Using the new, high-resolution stellar populations models developed in our group, we obtained accurate estimates of the mean luminosity-weighted ages and relative abundances of CN, Mg and Fe. We have f

Lee Clewley, Caroline van Breukelen, David Bonfield

We present a new cluster-finding algorithm based on a combination of the Voronoi Tessellation and Friends-Of-Friends methods. The algorithm utilises probability distribution functions derived from a photometric redshift analysis and is tested on simulated cluster-catalogues. We use a 9 band photometric catalogue over 0.5 square degrees in the Subaru XMM-Newt

Marcin Sawicki, Ikuru Iwata, Kouji Ohta, David Thompson

We study the properties of very faint, sub-L* Lyman break galaxies at z~2-5 - thus far a largely neglected but numerically and energetically very important population. We find that the LBG luminosity function undergoes luminosity-dependent evolution: the number of luminous galaxies remains constant while the number of faint ones grows with time. The total UV

M. Villar-Martin, A. Humphrey, C. De Breuck, R. Fosbury

About 54% of radio galaxies at z>3 and 8% of radio galaxies at 2<z<3 show unusually strong Ly-alpha emission, compared with the general population of high redshift (z>2) radio galaxies. These Ly-alpha excess objects (LAEs) show Ly-alpha/HeII values consistent with or above standard photoionization model predictions. We show that the most successful explanati

C. J. Evans, F. Bresolin, M. A. Urbaneja, G. Pietrzynski

We have obtained multi-object spectroscopy of luminous blue supergiants in NGC 3109, a galaxy at the periphery of the Local Group at ~1.3 Mpc. We present a detailed catalog including finding charts, V and I magnitudes, spectral classifications, and stellar radial velocities. The radial velocities are seen to trace the rotation curves obtained from studies of

Wei Wang, Yuanxing Gui, Ying Shao

Considering that the universe is filled with the nonrelativistic matter and dark energy and each component is respectively satisfied with its conservation condition in the absence of their interaction, we give the change rate of the fractional density and the density of dark energy from the conservation condition. It is clear that the fractional density of d

A. Kwang-Hua Chu

We make corrections on the paper by Frampton and Takahashi [{\it Astropart. Phys.} {\bf 22} (2004) 307]. Our focus is especially upon Eqs. (12-15) therein.

Ryan Barnett, Ari Turner, Eugene Demler

We respond to S.-K. Yip&#39;s criticism of our work on the classification of spinor condensates. We explain why his criticism is unfounded, emphasizing that the phases he mentions have been addressed in our paper cond-mat/0611230. To provide a constructive aspect to this response, we use it as an opportunity to show how our classification scheme makes explic

Brian Sharpee, Yong Zhang, Robert Williams, Eric Pellegrini

The s-process should occur in all but the lower mass progenitor stars of planetary nebulae, and this should be reflected in the chemical composition of the gas which is expelled to create the current planetary nebula shell. Weak forbidden emission lines are expected from several s-process elements in these shells, and have been searched for and in some cases

Emiliano Imeroni, Asad Naqvi

We study extended objects in the gravity dual of the N=1 beta-deformation of N=4 Super Yang-Mills theory. We identify probe brane configurations corresponding to giant gravitons and Wilson loops. In particular we identify a new class of objects, given by D5-branes wrapped on a two-torus with a world-volume gauge field strength turned on along the torus. Thes

Kaushik Majumdar

In this paper phase of a signal has been viewed from a different angle. According to this view a signal can have countably infinitely many phases, one associated with each Fourier component. In other words each frequency has a phase associated with it. It has been shown that if two signals are phase synchronous then the difference between phases at a given c

Ofer Aharony, Eva Silverstein

Highly supercritical strings (c much greater than 15) with a time-like linear dilaton provide a large class of solutions to string theory, in which closed string tachyon condensation is under control (and follows the worldsheet renormalization group flow). In this note we analyze the late-time stability of such backgrounds, including transitions between them

R. W. Crane, N. P. Armitage, A. Johansson, G. Sambandamurthy

We report a comprehensive study of the complex AC conductivity of thin effectively 2D amorphous superconducting InO_x films at zero applied field. Below a temperature scale T_c0 where the superconducting order parameter amplitude becomes well defined, there is a temperature where both the generalized superfluid stiffness acquires a frequency dependence and t

K. Soundararajan

Assuming the Riemann Hypothesis we obtain an upper bound for the moments of the Riemann zeta-function on the critical line. Our bound is nearly as sharp as the conjectured asymptotic formulae for these moments. The method extends to moments in families of $L$-functions.

Daniel Podolsky, Srinivas Raghu, Ashvin Vishwanath

When a superconductor is warmed above its critical temperature $T_c$, long range order is destroyed by fluctuations in the order parameter. These fluctuations can be probed by measurements of conductivity, diamagnetism, and of the Nernst effect. Here, we study a regime where superconductivity is destroyed by phase fluctuations arising from a dilute liquid of

Denis Borisov

We consider a singularly perturbed second order elliptic system in the whole space. The coefficients of the systems fast oscillate and depend both of slow and fast variables. We obtain the homogenized operator and in the uniform norm sense we construct the leading terms of the asymptotics expansion for the resolvent of the operator described by the system. T

M. J. Calderon, Belita Koiller, S. Das Sarma

We analyze several important issues for the single- and two-qubit operations in Si quantum computer architectures involving P donors close to a SiO2 interface. For a single donor, we investigate the donor-bound electron manipulation (i.e. 1-qubit operation) between the donor and the interface by electric and magnetic fields. We establish conditions to keep a

Angela Kopp, Karyn Le Hur

We study the entanglement between a qubit and its environment from the spin-boson model with Ohmic dissipation. Through a mapping to the anisotropic Kondo model, we derive the entropy of entanglement of the spin $E(α,Δ,h)$, where $α$ is the dissipation strength, $Δ$ is the tunneling amplitude between qubit states, and $h$ is the level asymmetry. For $1-α\gg

Greg Bothun, Stephen D. H. Hsu, Brian Murray

Using recent precision measurements of cosmological paramters, we re-examine whether these observations alone, independent of type Ia supernova surveys, are sufficient to imply the existence of dark energy. We find that best measurements of the age of the universe $t_0$, the Hubble parameter $H_0$ and the matter fraction $Ω_m$ strongly favor an equation of s

Alexandra Pope, Ranga-Ram Chary, Mark Dickinson, Douglas Scott

Submillimetre (sub-mm) galaxies have very high infrared (IR) luminosities and are thousands of times more numerous at z~2 than local ultra-luminous IR galaxies. They therefore represent a key phase in galaxy evolution which can be missed in optical surveys. Determining their contribution to the global star formation rate requires dissecting their IR emission

Dirk Grupe, John A. Nousek, Daniel E. vanden Berk, Peter W. A. Roming

We remark on the utility of an observational relation between the absorption column density in excess of the Galactic absorption column density, $ΔN_{\rm H} = N_{\rm H, fit} - N_{\rm H, gal}$, and redshift, z, determined from all 55 Swift-observed long bursts with spectroscopic redshifts as of 2006 December. The absorption column densities, $N_{\rm H, fit}$,

Eric V. Linder

The cosmological constant and many other possible origins for acceleration of the cosmic expansion possess variations in the dark energy properties slow on the Hubble time scale. Given that models with more rapid variation, or even phase transitions, are possible though, we examine the fineness in redshift with which cosmological probes can realistically be

Ram Sriharsha

I discuss some aspects of the moduli space of hyper-K{ä}hler four-fold compactifications of type II and ${\cal M}$- theories. The dimension of the moduli space of these theories is strictly bounded from above. As an example I study Hilb$^2(K3)$ and the generalized Kummer variety $K^2(T^4)$. In both cases RR-flux (or $G$-flux in ${\cal M}$-theory) must be tur

Steve K. Lamoreaux

A new neutron lifetime experiment employing frozen Fomblin has produced a result in significant disagreement with previous experiments that used liquid Fomblin near room temperature. This new experiment is subject to very few corrections, so the source of the discrepancy is a mystery. Here we theoretically investigate several possible systematic effects for

Jens Erler

After briefly reviewing the status of the standard model, I will focus mainly on polarized electron scattering and other tests of the weak neutral current. I will also address other low energy tests in which polarization degrees of freedom play a crucial role, including precision muon physics and searches for electric dipole moments.

Rodrigo Aros, Mauricio Romo, Nelson Zamorano

We explicitly calculate the induced gravity theory at the boundary of an asymptotically Anti-de Sitter five dimensional Einstein gravity. We also display the action that encodes the dynamics of radial diffeomorphisms. It is found that the induced theory is a four dimensional conformal gravity plus a scalar field. This calculation confirms some previous resul

Borut Bajc, Goran Senjanovic

We study the implementation of the type III seesaw in the ordinary nonsupersymmetric SU(5) grand unified theory. This allows for an alternative definition of the minimal SU(5) model, with the inclusion of the adjoint fermionic multiplet. The main prediction of the theory is the light fermionic SU(2) triplet with mass at the electroweak scale. Due to their ga

Françoise Détienne, Jean-François Rouet, Jean-Marie Burkhardt, Catherine Deleuze-Dordron

This paper presents a cognitive typology of reuse processes, and a cognitive typology of documenting processes. Empirical studies on design with reuse and on software documenting provide evidence for a generalized cognitive model. First, these studies emphasize the cyclical nature of design: cycles of planning, writing and revising occur. Second, natural lan

Daniel Robles-Llana, Martin Rocek, Frank Saueressig, Ulrich Theis

We find the D(-1) and D1-brane instanton contributions to the hypermultiplet moduli space of type IIB string compactifications on Calabi-Yau threefolds. These combine with known perturbative and worldsheet instanton corrections into a single modular invariant function that determines the hypermultiplet low-energy effective acction.

Helge Øystein Maakestad

Notes for some talks given at the seminar on characteristic classes at NTNU in autumn 2006. In the paper a proof of the existence of a Chern-character from complex K-theory to any cohomology theory with values in graded Q-algebras is given. The Chern-character respects the Adams and Steenrod operations.

Vladyslav C. Usenko, Matteo G. A. Paris

We address binary and quaternary communication channels based on correlated multiphoton two-mode states of radiation in the presence of losses. The protocol are based on photon number correlations and realized upon choosing a shared set of thresholds to convert the outcome of a joint photon number measurement into a symbol from a discrete alphabet. In partic

Paul R. Anderson, A. Fabbri

The universality of semiclassical gravity is investigated by considering the behavior of the quantities < ϕ^2 > and < {T^a}_b >, along with quantum corrections to the effective Newtonian potential in the far field limits of static spherically symmetric objects ranging from stars in the weak field Newtonian limit to black holes. For scalar fields it is shown

Thierry Masson

This informal introduction is an extended version of a three hours lecture given at the 6th Peyresq meeting ``Integrable systems and quantum field theory&#39;&#39;. In this lecture, we make an overview of some of the mathematical results which motivated the development of what is called noncommutative geometry. The first of these results is the theorem by Ge

J. F. Zhao, H. W. Ou, G. Wu, B. P. Xie

The electronic structure of a new charge-density-wave/ superconductor system, 1T-CuxTiSe2, has been studied by photoemission spectroscopy. A correlated semiconductor band structure is revealed for the undoped case. With Cu doping, the charge density wave is suppressed by the raising of the chemical potential, while the superconductivity is enhanced by the en

S. Liriano

Hanna Neumann asked whether it was possible for two non-isomorphic residually nilpotent finitely generated (fg) groups, one of them free, to share the lower central sequence. Gilbert Baumslag answered the question in the affirmative and thus gave rise to parafree groups. A group G is termed parafree of rank n if it is residually nilpotent and shares the lowe

S. Poindexter, N. Morgan, C. S. Kochanek, E. E. Falco

The mid-IR flux ratios F_A/F_B = 2.84 +/- 0.06 of the two images of the gravitationally lensed quasar HE 1104-1805 show no wavelength dependence to within 3% across 3.6-8.0 um, no time dependence over 6 months and agree with the broad emission line flux ratios. This indicates that the mid-IR emission likely comes from scales large enough to be little affecte

Mansoor ur Rehman, V. N. Senoguz, Qaisar Shafi

In their minimal form both supersymmetric and smooth hybrid inflation yield a scalar spectral index n_s close to 0.98, to be contrasted with the result n_s=0.951+0.015-0.019 from WMAP3. To realize better agreement, following hep-ph/0604198, we extend the parameter space of these models by employing a non-minimal Kaehler potential. We also discuss non-thermal

Chris Kurth, Ling Long

In this paper, we consider modular forms for finite index subgroups of the modular group whose Fourier coefficients are algebraic. It is well-known that the Fourier coefficients of any holomorphic modular form for a congruence subgroup (with algebraic coefficients) have bounded denominators. It was observed by Atkin and Swinnerton-Dyer that this is no longer

Yuri Bahturin, Michel Goze

The notion of a $Γ$-symmetric space is a generalization of the classical notion of a symmetric space, where a general finite abelian group $Γ$ replaces the group $Z_2$. The case $Γ=\Z_k$ has also been studied, from the algebraic point of view by V.Kac \cite{VK} and from the point of view of the differential geometry by Ledger, Obata, Kowalski or Wolf - Gray

R. H. Sanders

Below a threshold energy, gas in the constant density core of a triaxial galaxy can find no simple non-intersecting periodic orbit to act as an attractor for its trajectory (El-Zant et al. 2003). If a disc of gas arriving from further out in the galaxy dissipates sufficient energy to fall below this threshold, it will thereafter collapse into the very centre

R. S. Costas-Santos, F. Marcellan

It is well known that the classical families of orthogonal polynomials are characterized as eigenfunctions of a second order linear differential/difference operator. In this paper we present a study of classical orthogonal polynomials in a more general context by using the differential (or difference) calculus and Operator Theory. In such a way we obtain a u

Françoise Détienne, Willemien Visser

This paper presents an analysis of various forms of articulation between graphico-gestural and verbal modalities in parallel interactions between designers in a collaborative design situation. Based on our methodological framework, we illustrate several forms of multimodal articulations, that is, integrated and non-integrated, through extracts from a corpus

Y. S. Kim

According to Richard Feynman, the adventure of our science of physics is a perpetual attempt to recognize that the different aspects of nature are really different aspects of the same thing. It is therefore interesting to combine some, if not all, of Feynman&#39;s papers into one. The first of his three papers is on the ``rest of the universe&#39;&#39; conta

Jean-Luc Lehners, Paul McFadden, Neil Turok

We discuss the moduli space approximation for heterotic M-theory, both for the minimal case of two boundary branes only, and when a bulk brane is included. The resulting effective actions may be used to describe the cosmological dynamics in the regime where the branes are moving slowly, away from singularities. We make use of the recently derived colliding b

Jacob Ziv

Consider the case where consecutive blocks of N letters of a semi-infinite individual sequence X over a finite-alphabet are being compressed into binary sequences by some one-to-one mapping. No a-priori information about X is available at the encoder, which must therefore adopt a universal data-compression algorithm. It is known that if the universal LZ77 da

Michele R. Pestalozzi, A. Chrysostomou, J. Collett, V. Minier

Context: Methanol masers at 6.7GHz are recognised markers of high-mass star formation regions. The study of their distribution in the Galaxy gives important insights into the star formation activity of the Milky Way. We present a statistical analysis on the General Catalogue of 6.7GHz methanol masers in the Galaxy with the aim of extracting global properties

Florian Marhauser, Dominik Nickel, Michael Buballa, Jochen Wambach

We investigate the color-spin locked (CSL) phase of spin-one color- superconducting quark matter using a truncated Dyson-Schwinger equation for the quark propagator in Landau gauge. Starting from the most general parity conserving ansatz allowed by the CSL symmetry, the Dyson-Schwinger equation is solved self-consistently and dispersion relations are discuss

Christophe Bahadoran

We consider attractive particle systems in $\Z^d$ with product invariant measures. We prove that when particles are restricted to a subset of $\Z^d$, with birth and death dynamics at the boundaries, the hydrodynamic limit is given by the unique entropy solution of a conservation law, with boundary conditions in the sense of Bardos, Leroux and Nédélec. For th

Nathan Berkovits

In the pure spinor formalism for the superstring and supermembrane, supersymmetric invariants are constructed by integrating over five $θ$&#39;s in d=10 and over nine $θ$&#39;s in d=11. This pure spinor superspace is easily explained using the superform (or &#39;&#39;ectoplasm&#39;&#39;) method developed by Gates and collaborators, and generalizes the standa

Jianqiang Zhao

In this paper we shall define the renormalization of the multiple $q$-zeta values (M$q$ZV) which are special values of multiple $q$-zeta functions $ζ_q(s_1,...,s_d)$ when the arguments are all positive integers or all non-positive integers. This generalizes the work of Guo and Zhang (math.NT/0606076v3) on the renormalization of Euler-Zagier multiple zeta val

Nicolas Leprovost, Eun-Jin Kim

We study the effect of rotation on sheared turbulence, due to differential rotation. By solving quasi-linear equations for the fluctuating fields, we derive turbulence amplitude and turbulent transport coefficients, taking into account the effects of shear and rotation on turbulence. We focus on the regions of the tachocline near the equator and the poles wh

E. O. Kahya, V. K. Onemli

We consider a massless, minimally coupled scalar with a quartic self-interaction which is released in Bunch-Davies vacuum in locally de Sitter background of an inflating universe. It was shown, in this system, that quantum effects can induce a temporary phase of super-acceleration causing a violation of the Weak Energy Condition on cosmological scales. In th

Michael Galperin, Mark A. Ratner, Abraham Nitzan

Introduction (2) Experimental background: Test beds (8) Theoretical approaches: A microscopic model(10) The electron-phonon coupling(14)Time and energy scales(15) Theoretical methods(19)Numerical calculations(28) Incoherent vs. coherent transport (28) Inelastic tunneling spectroscopy: Experimental background(31) Theoretical considerations:the weak coupling l

Pierre Ca Grange, Ernst Werner

Quantum Field Theory with fields as Operator Valued Distributions with adequate test functions, -the basis of Epstein-Glaser approach known now as Causal Perturbation Theory-, is recalled. Its recent revival is due to new developments in understanding its renormalization structure, which was a major and somehow fatal disease to its widespread use in the seve

Ashok Das, J. Frenkel

We derive the properties of hard thermal effective actions in gauge theories from the point of view of Schwinger&#39;s proper time formulation. This analysis is simplified by introducing a set of generalized energy and momenta which are conserved and are non-local in general. These constants of motion, which embody energy-momentum exchanges between the field

Cheng-ping Huang, Qian-jin Wang, Yong-yuan Zhu

The light transmission through square and rectangular holes in a metal film has been studied. By taking account of plasma response of real metal on hole walls as well as metal surface, an analytical result for the transmission has been deduced, which agrees well with the experiments. We show that the light transmission involves both the diffraction modes and

Jean-Marie Burkhardt, Françoise Détienne, Susan Wiedenbeck

Previous studies on program comprehension were carried out largely in the context of procedural languages. Our purpose is to develop and evaluate a cognitive model of object-oriented (OO) program understanding. Our model is based on the van Dijk and Kintsch&#39;s model of text understanding (1983). One key aspect of this theoretical approach is the distincti

Géraldine Martin, Françoise Détienne, Elisabeth Lavigne

We present an empirical study aimed at analysing the use of viewpoints in an industrial Concurrent Engineering context. Our focus is on the viewpoints expressed in the argumentative process taking place in evaluation meetings. Our results show that arguments enabling a viewpoint or proposal to be defended are often characterized by the use of constraints. On

Françoise Détienne

Empirical studies on design have emphasised the role of memory of past solutions. Design involves the use of generic knowledge as well as episodic knowledge about past designs for analogous problems : in this way, it involves the reuse of past designs. We analyse this mechanism of reuse from a socio-cognitive viewpoint. According to a purely cognitive approa

Wung-Hong Huang

We first apply the transformation of mixing azimuthal and internal coordinate to the 11D M-theory with a stack N M2-branes to find the spacetime of a stack of N D2-branes with Melvin one-form in 10D IIA string theory, after the Kaluza-Klein reduction. Next, we apply the Melvin twist to the spacetime and perform the T duality to obtain the background of a sta

Jairo Z. Goncalves, Angel del Rio

Let $G$ be a finite group and $\Z G$ its integral group ring. We show that if $α$ is a non-trivial bicyclic unit of $\Z G$, then there are bicyclic units $β$ and $γ$ of different types, such that $\GEN{α,β}$ and $\GEN{α,γ}$ are non-abelian free groups. In case that $G$ is non-abelian of order coprime with 6, then we prove the existence of a bicyclic unit $u$

A. F. Krutov, V. M. Muzafarov, V. E. Troitsky

We present a convenient analytical parametrization of the deuteron wave function calculated within dispersion approach as a discrete superposition of Yukawa-type functions, in both configuration and momentum spaces.

Mark Y. Vilensky, Yehiam Prior, Ilya Sh. Averbukh

We propose a generic approach to nonresonant laser cooling of atoms/molecules in a bistable optical cavity. The method exemplifies a photonic version of Sisyphus cooling, in which the matter-dressed cavity extracts energy from the particles and discharges it to the external field as a result of sudden transitions between two stable states.

Sergey A. Melikhov

We review a cochain-free treatment of the classical van Kampen obstruction \theta to embeddability of an n-polyhedron into R^{2n} and consider several analogues and generalizations of \theta, including an extraordinary lift of \theta which in the manifold case has been studied by J.-P. Dax. The following results are obtained. - The mod 2 reduction of \theta

Charanjit S. Aulakh, Sumit K. Garg

The Supersymmetric SO(10) GUT based on the ${\bf{210\oplus 10\oplus 120\oplus 126\oplus {\bar{126}}}}$ Higgs system has 40 real superpotential parameters of which 2 can be fixed by the Light Higgs doublet fine tuning and one by the determination of the unification scale by the RG flow. It provides a minimal framework for the emergence of R-parity exact Super

Nenad Manojlovic, Zoltan Nagy

Elliptic quantum groups can be associated to solutions of the star-triangle relation of statistical mechanics. In this paper, we consider the particular case of the $E_{τ,η}(so_3)$ elliptic quantum group. In the context of algebraic Bethe ansatz, we construct the corresponding Bethe creation operator for the transfer matrix defined in an arbitrary representa

J. Rifà, F. Solov'eva, M. Villanueva

The intersection problem for additive (extended and non-extended) perfect codes, i.e. which are the possibilities for the number of codewords in the intersection of two additive codes C1 and C2 of the same length, is investigated. Lower and upper bounds for the intersection number are computed and, for any value between these bounds, codes which have this gi