May 2006 arXiv papers — page 35

Vassilios G. Papageorgiou, Anastasios G. Tongas, Alexander P. Veselov

A connection between the Yang-Baxter relation for maps and the multi-dimensional consistency property of integrable equations on quad-graphs is investigated. The approach is based on the symmetry analysis of the corresponding equations. It is shown that the Yang-Baxter variables can be chosen as invariants of the multi-parameter symmetry groups of the equati

Valentin D. Irtegov, Tatyana N. Titorenko

The paper presents some results of qualitative analysis of Kirchhoff's differential equations describing motion of a rigid body in ideal fluid in Sokolov's case. The research methods are based on Lyapunov's classical results. Methods of computer algebra implemented in the computer algebra system (CAS) "Mathematica" were also used. Combina

Vladimir Shchigolev

For an algebraically closed base field of characteristic p>0, a new algorithm to construct some non-zero GL(n-1)-high weight vectors of irreducible rational GL(n)-modules is suggested. It is based on successively applying Kleshchev's lowering operators to GL(n-1)-high weight vectors already obtained.

German A. Enciso, Morris W. Hirsch, Hal L. Smith

Classical results in the theory of monotone semiflows give sufficient conditions for the generic solution to converge toward an equilibrium or towards the set of equilibria (quasiconvergence). In this paper, we provide new formulations of these results in terms of the measure-theoretic notion of prevalence. For monotone reaction-diffusion systems with Neuman

Maurice Duits, Arno Kuijlaars

We study polynomials that are orthogonal with respect to a varying quartic weight \exp(-N(x^2/2+tx^4/4)) for t<0, where the orthogonality takes place on certain contours in the complex plane. Inspired by developments in 2D quantum gravity, Fokas, Its, and Kitaev, showed that there exists a critical value for t around which the asymptotics of the recurrence c

J. F. Jardine

Gerbes are locally connected presheaves of groupoids. They are classified up to local weak equivalence by path components in a 2-cocycle category taking values in all sheaves of groups, their isomorphisms and homotopies. If F is a full presheaf of sheaves of groups, isomorphisms and homotopies, then [*,BF] is isomorphic to equivalence classes of gerbes local

Eric Cator, Sergei Dobrynin

In the case of a rarefaction fan in a non-stationary Hammersley process, we explicitly calculate the asymptotic behavior of the process as we move out along a ray, and the asymptotic distribution of the angle within the rarefaction fan of a second class particle and a dual second class particle. Furthermore, we consider a stationary Hammersley process and us

J. F. Jardine

A cocycle category H(X,Y) is defined for objects X and Y in a model category, and it is shown that the set of morphisms [X,Y] is isomorphic to the set of path components of H(X,Y) provided the ambient model category is right proper and satisfies the extra condition that weak equivalences are closed under finite products. Various applications of this result a

M. Levine, R. Pandharipande

We define a cobordism theory in algebraic geometry based on normal crossing degenerations with double point singularities. The main result is the equivalence of double point cobordism to the theory of algebraic cobordism previously defined by Levine and Morel. Double point cobordism provides a simple, geometric presentation of algebraic cobordism theory. As

F. J. Herrera Govantes, M. A. Olalla Acosta, M. Spivakovsky

Let $K\to L$ be an algebraic field extension and $ν$ a valuation of $K$. The purpose of this paper is to describe the totality of extensions $\left\{ν&#39;\right\}$ of $ν$ to $L$ using a refined version of MacLane&#39;s key polynomials. In the basic case when $L$ is a finite separable extension and $rk ν=1$, we give an explicit description of the limit key p

Thomas Branson, A. Rod Gover

On pseudo-Riemannian manifolds of even dimension $n\geq 4$, with everywhere vanishing (Fefferman-Graham) obstruction tensor, we construct a complex of conformally invariant differential operators. The complex controls the infinitesimal deformations of obstruction-flat structures, and, in the case of Riemannian signature the complex is elliptic.

Mario Paschke, Andrzej Sitarz

We find and classify possible equivariant spin structures with Dirac operators on the noncommutative torus, proving that similarly as in the classical case the spectrum of the Dirac operator depends on the spin structure.

Kota Yoshioka

We show that the Fourier-Mukai transfortm on an abelian surface induces a birational map of the moduli space of stablke sheaves.

Oliver Cooley, Daniela Kühn, Deryk Osthus

Let K_r^- denote the graph obtained from K_r by deleting one edge. We show that for every integer r\ge 4 there exists an integer n_0=n_0(r) such that every graph G whose order n\ge n_0 is divisible by r and whose minimum degree is at least (1-1/chi_{cr}(K_r^-))n contains a perfect K_r^- packing, i.e. a collection of disjoint copies of K_r^- which covers all

Randy Cogill, Sanjay Lall

In this paper we study a dynamic resource allocation problem which we call the stochastic k-server problem. In this problem, requests for some service to be performed appear at various locations over time, and we have a collection of k mobile servers which are capable of servicing these requests. When servicing a request, we incur a cost equal to the distanc

Viktor L. Ginzburg

In this paper we make the first steps towards developing a theory of intersections of coisotropic submanifolds, similar to that for Lagrangian submanifolds. For coisotropic submanifolds satisfying a certain stability requirement we establish persistence of coisotropic intersections under Hamiltonian diffeomorphisms, akin to the Lagrangian intersection proper

Christopher J. Hillar, Darren Rhea

We give an accessible and modern description of the automorphisms of a finite abelian group $G$. Included is an explicit formula for the cardinality of $Aut(G)$.

Alexandru D. Ionescu Carlos E. Kenig

We prove that the Benjamin-Ono initial-value problem is locally well-posed for small, complex-valued data in Sobolev spaces with special low-frequency structure.

Michel Benaim, Raphael Rossignol

We extend a Gaussian functional inequality to a countable product of Gaussian measures. This inequality improves on the classical Poincare inequality for Gaussian measures. As an application, we prove that First Passage Percolation has sublinear variance when the edge times distribution belongs to a wide class of continuous distributions, including the expon

Stefan Kebekus, Luis Sola Conde

This survey paper discusses some of the recent progress in the study of rational curves on algebraic varieties. It was written for the survey volume of the priority programme &#34;Global Methods in Complex Geometry&#34;, supported by the DFG. To start, we discuss existence results for rational curves on foliated manifolds. We construct the tangent morphism,

Noemi Kurt

Consider the centered Gaussian field on the lattice $\mathbb{Z}^d,$ $d$ large enough, with covariances given by the inverse of $\sum_{j=k}^K q_j(-Δ)^j,$ where $Δ$ is the discrete Laplacian and $q_j \in \mathbb{R},k\leq j\leq K,$ the $q_j$ satisfying certain additional conditions. We extend a previously known result to show that the probability that all spins

Stefan Friedl, Taehee Kim

Every element in the first cohomology group of a 3--manifold is dual to embedded surfaces. The Thurston norm measures the minimal `complexity&#39; of such surfaces. For instance the Thurston norm of a knot complement determines the genus of the knot in the 3--sphere. We show that the degrees of twisted Alexander polynomials give lower bounds on the Thurston

Stephanie Cupit-Foutou, Dan Zaffran

Bosio generalized the construction by Meersseman of a family of non-algebraic compact complex manifolds of any dimension. We establish a link between Bosio&#39;s construction and GIT quotients. We show that his generalization parallels exactly the extension from Mumford&#39;s GIT to the more general GIT developed by Bialynicki-Birula and Swiecicka. This give

Kota Yoshioka

We construct the moduli of twisted sheaves on a projective variety. Then we generalize known results on the moduli space of usual sheaves on a K3 surface to the twisted case. Thus we consider the non-emptyness, the deformation type and the Fourier-Mukai transformation. As an application of our results, Daniel Huybrechts and Paolo Stellari prove Caldararu&#39

Daniel Grunberg

We present an overview of Gromov-Witten theory and its links with string theory compactifications, focussing on the GW potential as the generating function for topological string amplitudes at genus $g$. Restricting to Calabi-Yau target spaces, we give a complete derivation of the GW potential, discuss problems of multicovers and the infinite product express

David S. Berman, Neil B. Copland

This note covers various aspects of recent attempts to describe membranes ending on fivebranes using fuzzy geometry. In particular, we examine the Basu-Harvey equation and its relation to the Nahm equation as well as the consequences of using a non-associative algebra for the fuzzy three-sphere. This produces the tantalising result that the fuzzy funnel solu

B. H. Lavenda

No bootstrap assumption is needed to derive the exponential growth of the Hagedorn hadron mass spectrum: It is a consequence of the second law applied to a relativistic gas, and the relativistic equivalence between inertial mass and its heat content. The Hagedorn temperature occurs in the limit as the number of particles and their internal energy diverge suc

Gianluca Grignani, Marta Orselli, Bojan Ramadanovic, Gordon W. Semenoff

The one string-loop correction to the energies of two impurity BMN states are computed using IIB light-cone string field theory with an improved 3-string vertex that has been proposed by Dobashi and Yoneya. As in previous published computations, the string vertices are truncated to the 2-impurity channel. The result is compared with the prediction from non-p

Xiangdong Ji, Yingchuan Li, R. N. Mohapatra, S. Nasri

We study the origin of baryonic matter via leptogenesis in realistic SO(10) models, in particular, in a new lopsided mass matrix model introduced recently by three of the authors. By introducing simple CP-violating phases in the mass matrix of the right-handed neutrinos, the model generates sufficient baryon asymmetry without fine-tuning. We compare this res

Redamy Perez Ramos

We discuss correlations between two particles in jets at high energy colliders and exactly solve the MLLA evolution equations in the small x limit. We thus extend the Fong-Webber analysis to the region away from the hump of the single inclusive energy spectrum. We give our results for LEP, Tevatron and LHC energies, and compare with existing experimental dat

Namit Mahajan, Sukanta Panda

We investigate the impact of finite temperature effects on axions in the context of cosmology. The temperature dependence of the decay constant is modeled analogous to pions. For the two interesting cases considered here, we find that the temperature effects do lead to changes relevant for detailed and precise abundance and rate calculations. We also find th

Wei-Shu Hou, Makiko Nagashima, Andrea Soddu

Currently there are New Physics hints in mixing-induced CP violation S(phi K0), S(pi0 K0) < S(J/psi K0), unequal direct CP violation A(K+ pi-) differs A(K+ pi0), and maybe even in measured S(J/psi K0) vs prediction from global fit to other data. However, these hints either suffer from experimental uncertainties, or uncertain hadronic corrections, and are not

J. O. Eeg J. A. Macdonald Sørensen

The various decay modes of the type $B \to γD^* $ are dynamically different. In general there are factorizable contributions, and there are pole diagrams and pseudoscalar exchange contributions at meson level. The purpose of this paper is to point out that the decay modes $\bar{B_{d,s}^0} \to γD^{*0} $ have negligible contributions from such mechanisms, in c

J. A. Gracey

We use the Gribov-Zwanziger Lagrangian in QCD to evaluate the one loop correction to the gluon propagator as a function of the Gribov volume and verify that the propagator vanishes in the infrared limit. Using the corresponding correction to the Faddeev-Popov ghost propagator we construct the renormalization group invariant coupling constant, alpha^eff_S(p^2

J. Bernabeu, N. E. Mavromatos, J. Papavassiliou, A. Waldron-Lauda

We present a combined treatment of quantum-gravity-induced effects and intrinsic CPT violation in entangled neutral-Kaon states. Our analysis takes into consideration two types of effects: first, those associated with the loss of particle-antiparticle identity, as a result of the ill-defined nature of the CPT operator, and second, effects due to the non-unit

Yuri F. Orlov, William M. Morse, Yannis K. Semertzidis

A resonance method of measuring the electric dipole moment (EDM) of nuclei in storage rings is described, based on two new ideas: (1) Oscillating particles&#39; velocities in resonance with spin precession, and (2) alternately producing two sub-beams with different betatron tunes--one sub-beam to amplify and thus make it easier to correct ring imperfections

L3 Collaboration

The reactions gamma gamma -> pi^+pi^-pi^+pi^- and gamma gamma -> pi^+pi^0pi^-pi^0 are studied with the L3 detector at LEP in a data sample collected at centre-of-mass energies from 161GeV to 209GeV with a total integrated luminosity of 698/pb. A spin-parity-helicity analysis of the rho^0 rho^0 and rho^+ rho^- systems for two-photon centre-of-mass energies be

A Misaki, E Konishi, N Takahashi, Y Minorikawa

We examine neutrino events occurring inside the SuperKamiokande (SK) detector and those occurring outside the same detector using computer simulations. We analyze the zenith angle distribution of Fully Contained Events and show the method for the determination of the incident neutrino by the SK group is unreliable. The analysis of the neutrino events occurri

Filip Radlinski, Thorsten Joachims

This paper evaluates the robustness of learning from implicit feedback in web search. In particular, we create a model of user behavior by drawing upon user studies in laboratory and real-world settings. The model is used to understand the effect of user behavior on the performance of a learning algorithm for ranked retrieval. We explore a wide range of poss

Filip Radlinski, Thorsten Joachims

This paper presents a novel approach for using clickthrough data to learn ranked retrieval functions for web search results. We observe that users searching the web often perform a sequence, or chain, of queries with a similar information need. Using query chains, we generate new types of preference judgments from search engine logs, thus taking advantage of

Srinivas Shakkottai, R. Srikant

Internet worms, which spread in computer networks without human mediation, pose a severe threat to computer systems today. The rate of propagation of worms has been measured to be extremely high and they can infect a large fraction of their potential hosts in a short time. We study two different methods of patch dissemination to combat the spread of worms. W

Mihaela Dinsoreanu, Cristian Godja, Claudiu Anghel, Ioan Salomie

E-learning is nowadays one of the most interesting of the &#34;e- &#34; domains available through the Internet. The main problem to create a Web-based, virtual environment is to model the traditional domain and to implement the model using the most suitable technologies. We analyzed the distance learning domain and investigated the possibility to implement s

Tudor Marian, Bogdan Dumitriu, Mihaela Dinsoreanu, Ioan Salomie

Mobile agents research is clearly aiming towards imposing agent based development as the next generation of tools for writing software. This paper comes with its own contribution to this global goal by introducing a novel unifying framework meant to bring simplicity and interoperability to and among agent platforms as we know them today. In addition to this,

Mihaela Dinsoreanu, Ioan Salomie, Kalman Pusztai

The Unified Software Development Process (USDP) and UML have been now generally accepted as the standard methodology and modeling language for developing Object-Oriented Systems. Although Agent-based Systems introduces new issues, we consider that USDP and UML can be used in an extended manner for modeling Agent-based Systems. The paper presents a methodolog

Randy Cogill, Sanjay Lall

In this paper we analyze the average queue backlog in a combined input-output queued switch using a maximal size matching scheduling algorithm. We compare this average backlog to the average backlog achieved by an optimal switch. We model the cell arrival process as independent and identically distributed between time slots and uniformly distributed among in

F. Carbone, A. B. Kuzmenko, H. J. A. Molegraaf, E. van Heumen

We present the ab-plane optical conductivity of four single crystals of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+δ}$ (Bi2212) with different carrier doping levels from the strongly underdoped to the strongly overdoped range with $T_c$=66, 88, 77, and 67 K respectively. We focus on the redistribution of the low frequency optical spectral weight (SW) in the superconduc

Andor Kormanyos, Henning Schomerus

When a quantum-chaotic normal conductor is coupled to a superconductor, random-matrix theory predicts that a gap opens up in the excitation spectrum which is of universal size $E_g^{\rm RMT}\approx 0.3 \hbar/t_D$, where $t_D$ is the mean scattering time between Andreev reflections. We show that a scarred state of long lifetime $t_S\gg t_D$ suppresses the exc

Thomas J. Zega, Aubrey T. Hanbicki, Steven C. Erwin, Igor Zutic

We combine Z-contrast scanning transmission electron microscopy with density-functional-theory calculations to determine the atomic structure of the Fe/AlGaAs interface in spin-polarized light-emitting diodes. A 44% increase in spin-injection efficiency occurs after a low-temperature anneal, which produces an ordered, coherent interface consisting of a singl

E. Zaccarelli, I. Saika-Voivod, A. J. Moreno, E. La Nave

Recently we have studied, using numerical simulations, a limited valency model, i.e. an attractive square well model with a constraint on the maximum number of bonded neighbors. Studying a large region of temperatures $T$ and packing fractions $ϕ$, we have estimated the location of the liquid-gas phase separation spinodal and the loci of dynamic arrest, wher

Tommaso Roscilde, Stephan Haas

The interplay between site dilution and quantum fluctuations in S=1 Heisenberg antiferromagnets on the square lattice is investigated using quantum Monte Carlo simulations. Quantum fluctuations are tuned by a single-ion anisotropy D. In the clean limit, a sufficiently large D>D_c = 5.65(2) J forces each spin into its m_S=0 state, and thus destabilizes antife

Enrico Lipparini, Manuel Barranco, Francesc Malet, Martí Pi

The interplay between Rashba, Dresselhaus and Zeeman interactions in a quantum well submitted to an external magnetic field is studied by means of an accurate analytical solution of the Hamiltonian, including electron-electron interactions in a sum rule approach. This solution allows to discuss the influence of the spin-orbit coupling on some relevant quanti

Yue Yu

We study an array of cigar-like Bose atom condensates confined in a cylinder and examine the competition between the dipole-dipole and the short range interactions. The system is effectively reduced to a one-dimensional boson one with a contact and inverse square interactions. We call this system the Calogero-Sutherland-Lieb-Liniger gas. The universal proper

K. Winkler, G. Thalhammer, F. Lang, R. Grimm

Throughout physics, stable composite objects are usually formed via attractive forces, which allow the constituents to lower their energy by binding together. Repulsive forces separate particles in free space. However, in a structured environment such as a periodic potential and in the absence of dissipation, stable composite objects can exist even for repul

A. Agliolo Gallitto, G. Bonsignore, G. Giunchi, M. Li Vigni

We discuss the microwave second-harmonic generation in high-density bulk MgB2, prepared by the reactive liquid Mg infiltration technology. The intensity of the harmonic signal has been investigated as a function of temperature and amplitudes of the DC and microwave magnetic fields. The results are discussed in the framework of a phenomenological theory, base

Tobias J. Osborne

We present a certifiable algorithm to calculate the eigenvalue density function -- the number of eigenvalues within an infinitesimal interval -- for an arbitrary 1D interacting quantum spin system. Our method provides an arbitrarily accurate numerical representation for the smeared eigenvalue density function, which is the convolution of the eigenvalue densi

M. Babadi, M. R. Ejtehadi, R. Everaers

We derive exact expressions for the forces and torques between biaxial molecules interacting via the RE-squared potential, a recent variant of the Gay-Berne potential. Moreover, efficient routines have been provided for rigid body MD simulations, resulting in 1.6 times speedup compared to the two-point finite difference approach. It has also been shown that

D. Litvinov, D. Gerthsen, A. Rosenauer, M. Schowalter

We have investigated InGaAs layers grown by molecular-beam epitaxy on GaAs(001) by transmission electron microscopy (TEM) and photoluminescence spectroscopy. InGaAs layers with In-concentrations of 16, 25 and 28 % and respective thicknesses of 20, 22 and 23 monolayers were deposited at 535 C. The parameters were chosen to grow layers slightly above and below

D. Sanchez, L. E. Hueso, L. Granja, P. Levy

The physical properties of manganites depend strongly on sample morphology, probably due to strain. We investigate the influence of NdGaO3 substrates on the limit of the ferromagnetic-metallic phase field in La1-xCaxMnO3, doping with x=1% resolution. Films with x=0.40 show a metal-insulator transition, but the ferromagnetic volume fraction is half the spin a

Hiroshi Kohno, Gen Tatara, Junya Shibata

Effects of conduction electrons on magnetization dynamics, represented by spin torques, are calculated microscopically in the first order in spatial gradient and time derivative of magnetization. Special attention is paid to the so-called $β$-term and the Gilbert damping, $α$, in the presence of electrons&#39; spin-relaxation processes, which are modeled by

Hidetsugu Sakaguchi

A simple tight-coupling model of a molecular chemical engine is proposed. The efficiency of the chemical engine and its average velocity can be explicitly calculated. The diffusion constant is evaluated approximately using the fluctuation theorem. Langevin simulations with stochastic boundary conditions are performed and the numerical results are compared wi

Adolfo Avella, Ferdinando Mancini, Roland Hayn

The recently developed energy-scale-dependent Composite Operator Method is applied to the single-impurity Anderson model. A fully self-consistent solution is given and analyzed. At very low temperatures, the density of states presents, on the top of the high-energy background, a Kondo-like peak whose parameter dependence is discussed in detail. The proposed

Adolfo Avella, Ferdinando Mancini, Volodymyr Turkowski

The charge and spin dynamics of the two-dimensional Hubbard model in the paramagnetic phase is first studied by means of the two-pole approximation within the framework of the Composite Operator Method. The fully self-consistent scheme requires: no decoupling, the fulfillment of both Pauli principle and hydrodynamics constraints, the simultaneous solution of

Y. H. Pong, C. K. Law

We examine the basic mode structure of atomic Cooper pairs in an inhomogeneous Fermi gas. Based on the properties of Bogoliubov quasi-particle vacuum, the single particle density matrix and the anomalous density matrix share the same set of eigenfunctions. These eigenfunctions correspond to natural pairing orbits associated with the BCS ground state. We inve

Takeyoshi Ohashi, Haruhisa Kitano, Astutaka Maeda, Hiroyuki Akaike

We have measured the frequency and temperature dependences of complex ac conductivity, σ(ω)=σ_1(ω)-iσ_2(ω), of NbN films in zero magnetic field between 0.1 to 10 GHz using a microwave broadband technique. In the vicinity of superconducting critical temperature, Tc, both σ_1(ω) and σ_2(ω) showed a rapid increase in the low frequency limit owing to the fluctua

D. Balamurugan, R. Prasad

Using ab-initio electronic structure methods we have investigated the ground state structures and properties of neutral and charged SiH$_{m}$(m=1-4) and Si$_{2}$H$_{n}$(n=1-6) clusters which are produced in the plasma enhanced chemical vapor deposition process used in the preparation of hydrogenated amorphous silicon({\it{a}}-Si:H). Our results show that cha

C. A. Marianetti, G. Kotliar

Increasing experimental evidence is building which indicates that signatures of strong correlations are present in the Na rich region of Na$_x$CoO$_2$ (ie. $x\approx0.7$) and absent in the Na poor region (ie. $x\approx0.3$). This is unexpected given that NaCoO$_2$ is a band insulator and CoO$_2$ has an integer filled open shell making it a candidate for stro

Seiji Miyoshi, Tatsuya Uezu, Masato Okada

Conventional ensemble learning combines students in the space domain. On the other hand, in this paper we combine students in the time domain and call it time domain ensemble learning. In this paper, we analyze the generalization performance of time domain ensemble learning in the framework of online learning using a statistical mechanical method. We treat a

T. Yamamoto, Y. Nakamura, Yu. A. Pashkin, O. Astafiev

We propose a novel method for suppression of quasiparticle poisoning in Al Coulomb blockade devices. The method is based on creation of a proper energy gap profile along the device. In contrast to the previously used techniques, the energy gap is controlled by the film thickness. Our transport measurements confirm that the quasiparticle poisoning is suppress

S. Schmult, M. J. Manfra, A. Punnoose, A. M. Sergent

We present low temperature magnetoconductivity measurements of a density-tunable and high mobility two-dimensional electron gas confined in the wide bandgap GaN/AlGaN system. We observed pronounced anti-localization minima in the low-field conductivity, indicating the presence of strong spin-orbit coupling. Density dependent measurements of magnetoconductivi

Nicolay Korslund, Susanne Viefers

We study the composite fermion construction at and below the single vortex ($L=N$) state of weakly interacting rotating Bose gases, presenting a new method for handling the large number of derivatives typically occurring via the Slater determinant. Remarkably, the CF wave function at $L=N$ becomes {\em exact} in the large $N$ limit, even though this construc

Subir Sachdev, Kun Yang

We discuss ground state properties of a mixture of two fermion species which can bind to form a molecular boson. When the densities of the fermions are unbalanced, one or more Fermi surfaces can appear: we describe the constraints placed by Luttinger&#39;s theorem on the volumes enclosed by these surfaces in such Bose-Fermi mixtures. We also discuss the natu

Takahiro Hatano

Dynamical process where an edge dislocation in fcc copper bypasses an impenetrable precipitate is investigated by means of molecular dynamics simulation. A mechanism which is quite different from the Orowan mechanism is observed, where a dislocation leaves two prismatic loops near a precipitate: i.e. the Hirsch mechanism. It is found that the critical stress

Peter Foldi, Orsolya Kalman, Mihaly G. Benedict, F. M. Peeters

Quantum interference and spin-orbit interaction in a one-dimensional mesoscopic semiconductor ring with one input and two output leads can act as a spin beam splitter. Different polarization can be achieved in the two output channels from an originally totally unpolarized incoming spin state, very much like in a Stern-Gerlach apparatus. We determine the rele

F. Najarro, D. J. Hillier, J. Puls, T. Lanz

Recent calculations and analyses of O star spectra have revealed discrepancies between theory and observations, and between different theoretical calculations, for the strength of optical HeI singlet transitions.We investigate the source of these discrepancies. Using a non-LTE radiative transfer code we have undertaken detailed test calculations for a range

Duncan A. Forbes

We first discuss recent progress in using the Milky Way globular cluster (GC) system as a `test-bed&#39; for properties derived from integrated spectra and stellar population models. Standard techniques may give rise to spuriously high alpha-element ratios at low metallicities. We then discuss evidence for early epoch (z > 2) formation for most GCs in galaxi

F. Cuisinier, P. Westera, E. Telles, R. Buser

In this paper, we investigate the behaviour of the number of Lyman continuum ionizing photons as compared to the actual number of hydrogen recombinations in HII galaxies. We evaluate the number of ionizing photons from the population synthesis of spectra observed in the visible, extrapolating the spectra to the extreme ultraviolet (EUV), beyond the Lyman lim

Tomotsugu Goto

Ever since the co-existence of an active galactic nucleus (AGN) and a starburst was observationally discovered, there has been a significant controversy over whether there is a physical connection between starbursts and AGNs. If yes, it is a subject of interest to reveal which one triggers another. Here we bring a unique insight onto the subject by identifyi

P. Weltevrede, R. T. Edwards, B. W. Stappers

We present the statistical results of a systematic, unbiased search for subpulse modulation of 187 pulsars performed with the Westerbork Synthesis Radio Telescope (WSRT) in the Netherlands at an observing wavelength of 21 cm (Weltevrede et al. 2006). We have increased the list of pulsars that show the drifting subpulse phenomenon by 42, indicating that more

Randall K Smith, T. M. Dame, Elisa Costantini, Peter Predehl

Using Chandra observations we have measured the energy-resolved dust-scattered X-ray halo around the low-mass X-ray binary GX5-1, which shows signs of both singly- and multiply-scattered X-rays. We compared the observed X-ray halo at various energies to predictions from a range of dust models. These fits used both smoothly-distributed dust as well as dust in

M. Yildiz, K. Yakut, H. Bakis, A. Noels

We present our findings based on a detailed analysis for the binaries of the Hyades, in which the masses of the components are well known. We fit the models of components of a binary system to the observations so as to give the observed total V and B-V of that system and the observed slope of the main-sequence in the corresponding parts. According to our fin

M. Mathioudakis, D. S. Bloomfield, D. B. Jess, V. S. Dhillon

High time resolution observations of a white--light flare on the active star EQ PegB show evidence of intensity variations with a period of approximately 10 s. The period drifts to longer values during the decay phase of the flare. If the oscillation is interpreted as an impulsively--excited, standing--acoustic wave in a flare loop, the period implies a loop

Fumiharu Yamoto, Minoru Sekiya

Nonlinear numerical simulations are performed to investigate the density evolution in the dust layer of a protoplanetary disk due to the gravitational instability and dust settling toward the midplane. We assume the region where the radial pressure gradient at equilibrium is negligible so that the shear-induced instability is avoided, and also restrict to an

Takaya Nozawa, Takashi Kozasa, Asao Habe

We investigate the destruction of dust grains by sputtering in the high-velocity interstellar shocks driven by supernovae (SNe) in the early universe to reveal the dependence of the time-scale of dust destruction on the gas density $n_{{\rm H}, 0}$ in the interstellar medium (ISM) as well as on the progenitor mass $M_{\rm pr}$ and explosion energy $E_{\rm 51

Li-Feng Xing, Xiao-Bin Zhang, Jian-Yan Wei

We monitored the light variations of 22 weak-line T Tauri stars (WTTS) discovered among the X-ray sources in the field of the Taurus-Auriga cloud. The photometric variability of 12 out of these WTTS samples is confirmed. They are all proved to be in periodic variations. By using the methods of the Phase Dispersion Minimization (PDM) and Fourier analysis, the

Rene A. Ong

This paper presents a summary of the status of the field of very high-energy (VHE) gamma-ray astronomy, as of early 2006. The paper is based on the Rapporteur Talk given at the 29th International Cosmic Ray Conference in Pune, India (ICRC 2005). It covers astrophysical results from observations made by high-energy and very high-energy telescopes operating at

Ender Tekin, Aylin Yener

We consider the Gaussian Multiple Access Wire-Tap Channel (GMAC-WT). In this scenario, multiple users communicate with an intended receiver in the presence of an intelligent and informed wire-tapper who receives a degraded version of the signal at the receiver. We define suitable security measures for this multi-access environment. Using codebooks generated

Paola Gori-Giorgi, Julien Toulouse, Andreas Savin

The formalism of Kohn and Sham uses a specific (model) hamiltonian which highly simplifies the many-electron problem to that of noninteracting fermions. The theorem of Hohenberg and Kohn tells us that, for a given ground state density, this hamiltonian is unique. In principle, this density can be chosen as that of the real, interacting system. To obtain the

James Lindesay

Previous work developed a space-time metric with two cosmological scales; one that conveniently describes the classical evolution of the dynamics, and the other describing a scale associated with macroscopic quantum aspects like vacuum energy. The present work expands upon the dynamics of these scales to demonstrate the usefulness of these coordinates for de

Yariv Kafri, Anatoli Polkovnikov

We consider the unbinding of a directed polymer in a random media from a wall in $d=1+1$ dimensions and a simple one-dimensional model for DNA unzipping. Using the replica trick we show that the restricted partition functions of these problems are {\em identical} up to an overall normalization factor. Our finding gives an example of a generalization of the s

Ahmad Idilbi, Xiangdong Ji, Feng Yuan

We apply the effective field theoretic (EFT) approach to resum the large perturbative logarithms arising when partonic hard scattering cross-sections are taken to the threshold limit. We consider deep inelastic scattering, Drell-Yan lepton pair production and the standard model Higgs production through gluon-gluon fusion via heavy-top loop. We demonstrate th

W. F. Kao

The existence and stability analysis of an inflationary solution in a $D+4$-dimensional anisotropic induced gravity is presented in this paper. Nontrivial conditions in the field equations are shown to be compatible with a cosmological model in which the 4-dimension external space evolves inflationary, while, the D-dimension internal one is static. In partic

Aykutlu Dana, Imran Akca, Orcun Ergun, Atilla Aydinli

Understanding charging mechanisms and charge retention dynamics of nanocrystal memory devices is important in optimization of device design. Capacitance spectroscopy on PECVD grown germanium nanocrystals embedded in a silicon oxide matrix was performed. Dynamic measurements of discharge dynamics are carried out. Charge decay is modelled by assuming storage o

Michael J. Kozdron, Gregory F. Lawler

We define multiple chordal SLEs in a simply connected domain by considering a natural configurational measure on paths. We show how to construct these measures so that they are conformally covariant and satisfy certain boundary perturbation and Markov properties, as well as a cascade relation. As an example of our construction, we derive the scaling limit of

Stephen L. Adler

We study lower and upper bounds on the parameters for stochastic state vector reduction, focusing on the mass-proportional continuous spontaneous localization (CSL) model. We show that the assumption that the state vector is reduced whan a latent image is formed, in photography or etched track detection, requires a CSL rate parameter $λ$ that is larger than

T. Koponen, J. Kinnunen, J. -P. Martikainen, L. M. Jensen

We consider pairing in a two-component atomic Fermi gas, in a three-dimensional optical lattice, when the components have unequal densities, i.e. the gas is polarized. We show that a superfluid where the translational symmetry is broken by a finite Cooper pair momentum, namely an FFLO-type state, minimizes the Helmholtz free energy of the system. We demonstr

Xiaotang Bai, Naihong Hu

The presentation of two-parameter quantum groups of type E-series in the sense of Benkart-Witherspoon [BW1] is given, which has a Drinfel&#39;d quantum double structure. The universal $R$-matrix and a convex PBW-type basis are described for type E_6 (as a sample), and the conditions of those isomorphisms from these quantum groups into the one-parameter quant

Y. Brihaye, F. Bakkali Taheri

We study the classical solutions of the Einstein-Yang-Mills model in five dimensions in the presence of a cosmological constant $Λ$. Using a spherically symmetric ansatz and assuming that the fields do not depend on the extra dimension, we transform the equations into a set of differential equations that we solve numerically. We construct new types of regula

Y. Brihaye, T. Delsate

Static and inflating brane world models are considered in $4+n$-dimensions with a non zero bulk cosmological constant and with a hyper-spherically symmetric topological defect residing in the $n$ extra dimensions. Several vacuum solutions can be constructed explicitely when the bulk and inflating constants are non zero. We study how these solutions are defor

Victor L. Chernyak

The &#34;handbag&#34; model was proposed as an alternative, at the present day energies, to the leading term QCD predictions for some hard exclusive processes. The recent precise data from the Belle Collaboration on the large angle cross sections $γγ--> ππ, KK $ allow a check of these two approaches to be performed. It is shown that the handbag model fails t

Ching Hung Lam, Hiroshi Yamauchi

In this paper, we study the structure of a general framed vertex operator algebra. We show that the structure codes (C,D) of a framed VOA V satisfy certain duality conditions. As a consequence, we prove that every framed VOA is a simple current extension of the associated binary code VOA V_C. This result would give a prospect on the classification of framed