July 2007 arXiv papers — page 12

K. M. Graczyk, J. T. Sobczyk

Vector and axial form factors in the quark resonance model are analyzed with a combination of theoretical and phenomenological arguments. The new form of form factors is deduced from $Δ$(1232) excitation models and available data. The vector part is shown to agree with the resonant contribution to electron-proton inclusive $F_2$ data. The axial part is obtai

M. Aichhorn, E. Arrigoni, M. Potthoff, W. Hanke

Cooperation and competition between the antiferromagnetic, d-wave superconducting and Mott-insulating states are explored for the two-dimensional Hubbard model including nearest and next-nearest-neighbor hoppings at zero temperature. Using the variational cluster approach with clusters of different shapes and sizes up to 10 sites, it is found that the doping

M. Heydari-Fard, H. Razmi, H. R. Sepangi

Using a confining potential, we consider spherically symmetric vacuum (static black hole) solutions in a brane-world scenario. Working with a constant curvature bulk, two interesting cases/solutions are studied. A Schwarzschild-de Sitter black hole solution similar to the standard solution in the presence of a cosmological constant is obtained which confirms

J. Gluza, F. Haas, K. Kajda, T. Riemann

Feynman diagrams may be evaluated by Mellin-Barnes representations of their Feynman parameter integrals in d=4-2\eps dimensions. Recently, the Mathematica toolkit AMBRE has been developed for the automatic derivation of such representations with a loop-by-loop approach. We describe the package and exemplify its use with the \eps-expansion of the massive one-

Paul S. Muhly, Dana P. Williams

We provide an exposition and proof of Renault's equivalence theorem for crossed products by locally Hausdorff, locally compact groupoids. Our approach stresses the bundle approach, concrete imprimitivity bimodules and is a preamble to a detailed treatment of the Brauer semigroup for a locally Hausdorff, locally compact groupoid.

Rudi Schäfer, Markus Sjölin, Andreas Sundin, Michal Wolanski

We set up a structural model to study credit risk for a portfolio containing several or many credit contracts. The model is based on a jump--diffusion process for the risk factors, i.e. for the company assets. We also include correlations between the companies. We discuss that models of this type have much in common with other problems in statistical physics

A. J. Hudson, R. M. Stevenson, A. J. Bennett, R. J. Young

We study the effect of the exciton fine-structure splitting on the polarisation-entanglement of photon pairs produced by the biexciton cascade in a single quantum dot. The entanglement is found to persist despite separations between the intermediate energy levels of up to 4 micro-eV. Measurements demonstrate that entanglement of the photon pair is robust to

J. Elbs, Yu. M. Bunkov, E. Collin, H. Godfrin

Deformation of aerogel strongly modifies the orientation of the order parameter of superfluid 3He confined in aerogel. We used a radial squeezing of aerogel to keep the orbital angular momentum of the 3He Cooper pairs in the plane perpendicular to the magnetic field. We did not find strong evidence for a "polar" phase, with a nodal line along the equ

Christophe Mourougane, Shigeharu Takayama

Using the harmonic theory developed by Takegoshi for representation of relative cohomology and the framework of computation of curvature of direct images bundles by Berndtsson, we prove that the higher direct images by a smooth morphism of the relative canonical bundle twisted by a semi-positive vector bundle are locally free and semi-positively curved, when

Matthias Baenninger, Arindam Ghosh, Michael Pepper, Harvey E. Beere

We report an universal behaviour of hopping transport in strongly interacting mesoscopic two-dimensional electron systems (2DES). In a certain window of background disorder, the resistivity at low perpendicular magnetic fields follows the expected relation $ρ(B_\perp) = ρ_{\rm{B}}\exp(αB_\perp^2)$. The prefactor $ρ_{\rm{B}}$ decreases exponentially with incr

F. Bassetti, M. Cosentino Lagomarsino, S. Mandrá

We introduce and study a class of exchangeable random graph ensembles. They can be used as statistical null models for empirical networks, and as a tool for theoretical investigations. We provide general theorems that carachterize the degree distribution of the ensemble graphs, together with some features that are important for applications, such as subgraph

C. Sliwa, T. Dietl

Spin splitting of photoelectrons in p-type and electrons in n-type III-V Mn-based diluted magnetic semiconductors is studied theoretically. It is demonstrated that the unusual sign and magnitude of the apparent s-d exchange integral reported for GaAs:Mn arises from exchange interactions between electrons and holes bound to Mn acceptors. This interaction domi

Steven Gottlieb, Heechang Na, Kazuhiro Nagata

In the staggered fermion formulation of lattice QCD, we construct diquark operators which are to be embedded in singly heavy baryons. The group theoretical connections between continuum and lattice staggered diquark representations are established.

Joanna Jaroszewska, Michal Rams

We consider measures which are invariant under a measurable iterated function system with positive, place-dependent probabilities in a separable metric space. We provide an upper bound of the Hausdorff dimension of such a measure if it is ergodic. We also prove that it is ergodic iff the related skew product is.

Alessandro D'Adda, Issaku Kanamori, Noboru Kawamoto, Kazuhiro Nagata

We propose a lattice formulation of three dimensional super Yang-Mills model with a twisted N=4 supersymmetry. The extended supersymmetry algebra of all the eight supercharges is fully and exactly realized on the lattice with a modified "Leibniz rule". The formulation we employ here is a three dimensional extension of manifestly gauge covariant metho

Nansen Petrosyan

There are characteristic classes that are the obstructions to the vanishing of the differentials in the Lyndon-Hochischild-Serre spectral sequence of an extension of an integral lattice L by a group G. These characteristic classes exist in a given page of the spectral sequence provided the differentials in the previous pages are all zero. When L decomposes i

Lorenzo Iorio

In this paper we explore the consequences of the recent determination of the mass m=(8.7 +/- 0.8)M_Sun of Cygnus X-1, obtained from the Quasi-Periodic Oscillation (QPO)-photon index correlation scaling, on the orbital and physical properties of the binary system HDE 226868/Cygnus X-1. By using such a result and the latest spectroscopic optical data of the HD

Camille Bonvin, Ruth Durrer, Pedro G. Ferreira, Glenn Starkman

It has been shown that generalized Einstein-Aether theories may lead to significant modifications to the non-relativistic limit of the Einstein equations. In this paper we study the effect of a general class of such theories on the Solar System. We consider corrections to the gravitational potential in negative and positive powers of distance from the source

Corneliu Sochichiu

Given a renormalizable theory we construct the dilatation operator, in the sense of generator of RG flow of composite operators. The generator is found as a differential operator acting on the space of normal symbols of composite operators in the theory. In the spirit of AdS/CFT correspondence, this operator is interpreted as the Hamiltonian of the dual theo

H. W. Liu, T. Fujisawa, Y. Ono, H. Inokawa

We present measurements of resonant tunneling through discrete energy levels of a silicon double quantum dot formed in a thin silicon-on-insulator layer. In the absence of piezoelectric phonon coupling, spontaneous phonon emission with deformation-potential coupling accounts for inelastic tunneling through the ground states of the two dots. Such transport me

Alberto Bernacchia

A recent experiment suggests that neural circuits may alternatively implement continuous or discrete attractors, depending on the training set up. In recurrent neural network models, continuous and discrete attractors are separately modeled by distinct forms of synaptic prescriptions (learning rules). Here, we report a solvable network model, endowed with He

Julia Goedecke, Tim Van der Linden

It is well known that Barr and Beck's definition of comonadic homology makes sense also with a functor of coefficients taking values in a semi-abelian category instead of an abelian one. The question arises whether such a homology theory has the same convenient properties as in the abelian case. Here we focus on independence of the chosen comonad: condit

Frank Klinker

We construct a geometric structure on deformed supermanifolds as a certain subalgebra of the vector fields. In the classical limit we obtain a decoupling of the infinitesimal odd and even transformations, whereas in the semiclassical limit the result is a representation of the supersymmetry algebra. In the case of mass preserving structure we describe all hi

Nicolas Champagnat, Sylvie Roelly

A multitype Dawson-Watanabe process is conditioned, in subcritical and critical cases, on non-extinction in the remote future. On every finite time interval, its distribution is absolutely continuous with respect to the law of the unconditioned process. A martingale problem characterization is also given. Several results on the long time behavior of the cond

Li Cheng, Shiping Feng

The doping and energy evolution of the magnetic excitations of the electron-doped cuprate superconductor Pr$_{0.88}$LaCe$_{0.12}$CuO$_{4-δ}$ in the superconducting state is studied based on the kinetic energy driven superconducting mechanism. It is shown that there is a broad commensurate scattering peak at low energy, then the resonance energy is located am

Helge Krueger, Gerald Teschl

We extend relative oscillation theory to the case of Sturm--Liouville operators $H u = r^{-1}(-(pu')'+q u)$ with different $p$'s. We show that the weighted number of zeros of Wronskians of certain solutions equals the value of Krein's spectral shift function inside essential spectral gaps.

Gregory Arone

For smooth manifolds $M$ and $N$, let $\Ebar(M, N)$ be the homotopy fiber of the map $\Emb(M, N)\longrightarrow \Imm(M, N)$. Consider the functor from the category of Euclidean spaces to the category of spectra, defined by the formula $V\mapsto Σ^\infty\Ebar(M, N\times V)$. In this paper, we describe the Taylor polynomials of this functor, in the sense of M.

Zeng Jiwen

Let $G$ be a finite group and $N$ be a normal subgroup of $G$. Let $J=J(F[N])$ denote the Jacboson radical of $F[N]$ and $I={\rm Ann}(J)=\{α\in F[G]|Jα=0\}$. We have another algebra $F[G]/I$. We study the decomposition of Cartan matrix of $F[G]$ according to $F[G/N]$ and $F[G]/I$. This decomposition establishs some connections between Cartan invariants and c

J. Brodzicka, H. Palka

We report the observation of a new $D_{sJ}$ meson produced in $B^{+} \to \bar{D}^{0} D_{sJ} \to \bar{D}^{0} D^{0} K^{+}$. This state has a mass of $M=2708 \pm 9 ^{+11}_{-10} \rm{MeV}/{\it c}^{2}$, a width $Γ= 108 \pm 23 ^{+36}_{-31} ~\rm{MeV}/ {\it c}^{2}$ and a $1^{-}$ spin-parity. The results are based on an analysis of 449 million $B\bar{B}$ events collec

Jason Kumar, Arvind Rajaraman, James D. Wells

We investigate the phenomenology of new abelian gauge bosons, which we denote as $X$ bosons, that suffer a mixed anomaly with the Standard Model, but are made self-consistent by the Green-Schwarz mechanism. A distinguishing aspect of the resulting effective theory is the decay of $X$ bosons into Standard Model gauge bosons, $X\to ZZ, WW, γZ$. We compute the

W. Struyve, H. Westman

We present a way to construct a pilot-wave model for quantum electrodynamics. The idea is to introduce beables corresponding only to the bosonic degrees of freedom and not to the fermionic degrees of freedom of the quantum state. We show that this is sufficient to reproduce the quantum predictions. The beables will be field beables corresponding to the elect

Bei Jia, Xi-Guo Lee

We study a mechanism, inspired from the mechanism for generating the gauge hierarchy in Randall-Sundrum model, to investigate the cosmological constant problem. First we analyze the bulk cosmological constant and brane vacuum energies in RS model. We show that the five-dimensional bulk cosmological constant and the vacuum energies of the two branes all obtai

G. Lavaux, R. Mohayaee, S. Colombi, R. B. Tully

Lagrangian reconstruction of large-scale peculiar velocity fields can be strongly affected by observational biases. We develop a thorough analysis of these systematic effects by relying on specially selected mock catalogues. For the purpose of this paper, we use the MAK reconstruction method, although any other Lagrangian reconstruction method should be sens

Taras Yavors'kii, Tom Fennell, Michel J. P. Gingras, Steven T. Bramwell

Dy2Ti2O7 is a geometrically frustrated magnetic material with a strongly correlated spin ice regime that extends from 1 K down to as low as 60 mK. The diffuse elastic neutron scattering intensities in the spin ice regime can be remarkably well described by a phenomenological model of weakly interacting hexagonal spin clusters, as invoked in other geometrical

A. E. Shabad, V. V. Usov

In an external constant magnetic field, so strong that the electron Larmour length is much shorter than its Compton length, we consider the modification of the Coulomb potential of a point charge owing to the vacuum polarization. We establish a short-range component of the static interaction in the Larmour scale, expressed as a Yukawa-like law, and reveal th

Derrick Hart, Alex Iosevich, Doowon Koh, Misha Rudnev

We prove a point-wise and average bound for the number of incidences between points and hyper-planes in vector spaces over finite fields. While our estimates are, in general, sharp, we observe an improvement for product sets and sets contained in a sphere. We use these incidence bounds to obtain significant improvements on the arithmetic problem of covering

D. Roglic

This work exposes which mechanisms and procesess in the Nature of evolution compute a function not computable by Turing machine. The computer with intelligence that is not higher than one bacteria population could have, but with efficency to solve the problems that are non-computable by Turing machine is represented. This theoretical construction is called U

Derek Homeier, Nicole F. Allard, France Allard

Ultracool stellar atmospheres show absorption by alkali resonance lines severely broadened by collisions with neutral perturbers. In the coolest and densest atmospheres, such as those of T dwarfs, Na I and K I broadened by molecular hydrogen and helium can come to dominate the entire optical spectrum. Their profiles have been successfully modelled with accur

Huey-Wen Lin

I review recent progress in calculating |V_{us}| from lattice QCD kaon and hyperon systems. A preliminary result from the first dynamical calculation in the hyperon channel is included.

Athanasios N. Chantis, Kirill D. Belashchenko, Darryl L. Smith, Evgeny Y. Tsymbal

A minority-spin resonant state at the Fe/GaAs(001) interface is predicted to reverse the spin polarization with voltage bias of electrons transmitted across this interface. Using a Green's function approach within the local spin density approximation we calculate spin-dependent current in a Fe/GaAs/Cu tunnel junction as a function of applied bias voltage

Wenshan Cai, Uday K. Chettiar, Alexander V. Kildishev, Graeme W. Milton

In an electromagnetic cloak based on a transformation approach, reduced sets of material properties are generally favored due to their easier implementation in reality, although a seemingly inevitable drawback of undesired reflection exists in such cloaks. Here we suggest using high-order transformations to create smooth moduli at the outer boundary of the c

Donald Yau

The deformation bicomplex of a module-algebra over a bialgebra is constructed. It is then applied to study algebraic deformations in which both the module structure and the algebra structure are deformed. The cases of module-coalgebras, comodule-(co)algebras, and (co)module-bialgebras are also considered.

Bradley E. Warren, Helmut Jerjen, Bärbel S. Koribalski

We present an analysis of the atomic hydrogen and stellar properties of 38 late-type galaxies in the local Universe covering a wide range of HI mass-to-light ratios (M_HI/L_B), stellar luminosities, and surface brightnesses. From these data we have identified an upper envelope for the M_HI/L_B as a function of galaxy luminosity. This implies an empirical rel

V. Hinze-Hoare

The History of HCI is briefly reviewed together with three HCI models and structure including CSCW, CSCL and CSCR. It is shown that a number of authorities consider HCI to be a fragmented discipline with no agreed set of unifying design principles. An analysis of usability criteria based upon citation frequency of authors is performed in order to discover th

Roman Rafikov

In the initial formation stages young stars must acquire a significant fraction of their mass by accretion from a circumstellar disk that forms in the center of a collapsing protostellar cloud. Throughout this period mass accretion rates through the disk can reach 10^{-6}-10^{-5} M_Sun/yr leading to substantial energy release in the vicinity of stellar surfa

David Eichler, Hadar Manis

Gamma ray bursts (GRB's) often feature subpulses that have a distinctively asymmetric profile -- they rise quickly and decay much more slowly, while their spectrum softens slightly with observer time. It is suggested that these subpulses are caused by slow baryonic clouds embedded within a primary $γ$-ray beam, which scatter the $γ$-radiation into our li

David R. Law, Charles C. Steidel, Dawn K. Erb, James E. Larkin

We present early results from an ongoing study of the kinematic structure of star-forming galaxies at redshift z ~ 2 - 3 using integral-field spectroscopy of rest-frame optical nebular emission lines in combination with Keck laser guide star adaptive optics (LGSAO). We show kinematic maps of 3 target galaxies Q1623-BX453, Q0449-BX93, and DSF2237a-C2 located

M. Cramer, S. Ospelkaus, C. Ospelkaus, K. Bongs

Mixtures of bosonic and fermionic atoms in optical lattices provide a promising arena to study strongly correlated systems. In experiments realizing such mixtures in the quantum degenerate regime the temperature is a key parameter. In this work, we investigate the intrinsic heating and cooling effects due to an entropy-preserving raising of the optical latti

Deqiang Sun, Ar. Abanov, V. L. Pokrovsky

The problem of molecular production from degenerate gas of fermions at a wide Feshbach resonance, in a single-mode approximation, is reduced to the linear Landau-Zener problem for operators. The strong interaction leads to significant renormalization of the gap between adiabatic levels. In contrast to static problem the close vicinity of exact resonance does

X. Ke, R. S. Freitas, B. G. Ueland, G. C. Lau

Water ice and spin ice are important model systems in which theory can directly account for zero point entropy associated with quenched configurational disorder. Spin ice differs from water ice in the important respect that its fundamental constituents, the spins of the magnetic ions, can be removed through replacement with non-magnetic ions while keeping th

Carlos H. Grossi

We prove a conjecture of R. Schwartz about the type of some complex hyperbolic triangle groups.

G. A. Shields, E. W. Bonning, S. Salviander

Mergers of spinning black holes can give recoil velocities from gravitational radiation up to several thousand km/s. A recoiling supermassive black hole in an AGN can retain the inner part of its accretion disk, providing fuel for continuing AGN activity. Using AGN in the Sloan Digital Sky Survey (SDSS) that show velocity shifts of the broad emission lines r

A. Ganguly, L. M. Nieto

Second order supersymmetric approach is taken to the system describing motion of a quantum particle in a potential endowed with position-dependent effective mass. It is shown that the intertwining relations between second order partner Hamiltonians may be exploited to obtain a simple shape-invariant condition. Indeed a novel relation between potential and ma

J. Hwang, T. Timusk, J. P. Carbotte

The study of bosonic modes that couple to the charge carriers is a key element in understanding superconductivity. Lee et al. have used atomic-resolution scanning tunneling spectroscopy (STM) in an attempt to extract the spectrum of of these modes in the high temperature superconductor Bi2Sr2CaCu2O8+d and they found a mode whose frequency did not depend on d

Igor Markov, Yaoyun Shi

Many hard algorithmic problems dealing with graphs, circuits, formulas and constraints admit polynomial-time upper bounds if the underlying graph has small treewidth. The same problems often encourage reducing the maximal degree of vertices to simplify theoretical arguments or address practical concerns. Such degree reduction can be performed through a seque

P. D. Mininni, A. Pouquet

We present a numerical analysis of an incompressible decaying magnetohydrodynamic turbulence run on a grid of 1536^3 points. The Taylor Reynolds number at the maximum of dissipation is ~1100, and the initial condition is a superposition of large scale ABC flows and random noise at small scales, with no uniform magnetic field. The initial kinetic and magnetic

Rene Bellwied

I will review RHIC data with respect to the intriguing possibility that the hadron production mechanism in the produced partonic medium might be different than in vacuum. I will use the measurements of collective features, such as flow and quenching of identified particles, to show that different regions of the particle momentum spectrum are likely populated

P. Liebing

Hermes has measured longitudinal double spin asymmetries as a function of transverse momentum pT using charged inclusive hadrons from electroproduction off a deuterium target. At pT>1 GeV, the asymmetries are sensitive to the spin dependent gluon distribution Delta g. To extract the gluon polarization Delta g/g, information on the background asymmetry and th

François Ladieu, Caroline Thibierge, Denis L'Hôte

We have measured the linear dielectric susceptibility of two molecular glass formers close to Tg in order to estimate the size of the dynamically correlated clusters of molecules which are expected to govern the physics of glass formation. This size has been shown to be related to the dynamic dielectric susceptibility dEps(w)/dT (Eps : dielectric susceptibil

Chris Cicotta, Joel Foisy, Tom Reilly, Sara Revzi

A graph G is intrinsically S^1-linked if for every embedding of the vertices of G into S^1, vertices that form the endpoints of two disjoint edges in G form a non-split link in the embedding. We show that a graph is intrinsically S^1-linked if and only if it is not outer-planar. A graph is outer-flat if it can be embedded in the 3-ball such that all of its v

A. Pimenov, A. Loidl, A. A. Mukhin, V. D. Travkin

Dielectric permittivity spectra of yttrium-doped EuMnO$_3$ in the composition range 0 =< x =< 0.5 have been investigated in the terahertz frequency range. Magnetoelectric contributions to the permittivity were observed in all compositions for ac electric fields parallel to the crystallographic a-axis. Well defined electromagnons exist for x >= 0.2 close to ν

H. Ingerslev Jørgensen, T. Novotný, K. Grove-Rasmussen, K. Flensberg

We report on quantum dot based Josephson junctions designed specifically for measuring the supercurrent. From high-accuracy fitting of the current-voltage characteristics we determine the full magnitude of the supercurrent (critical current). Strong gate modulation of the critical current is observed through several consecutive Coulomb blockade oscillations.

Hua Zhong Li

In a recent letter [Phy. Rev. Lett. 95, 080502 (2005)], it is claimed that based on a new kind of quantum mechanical phase of wave function which is neither dynamical nor geometrical a new kind of phase gate for quantum computation is discovered. The origin of this phase is the adiabatic evolution of a dark state. I would like to point out that these claims

C. Burrage, A. C. Davis

P-term potentials can give rise to Nielsen-Olesen or semi-local cosmic strings. We present a general analysis of these cosmic strings where we derive the Bogomol&#39;nyi equations and field profiles for both types of string and discuss their stability. We give an analysis of the fermionic zero modes that could live on the strings and a brief discussion of th

Tao Hu, B. I. Shklovskii

Proteins are known to locate their specific targets on DNA up to two orders of magnitude faster than predicted by the Smoluchowski three-dimensional diffusion rate. One of the mechanisms proposed to resolve this discrepancy is termed &#34;intersegment transfer&#34;. Many proteins have two DNA binding sites and can transfer from one DNA segment to another wit

Salman S. Rogers, Thomas A. Waigh, Xiubo Zhao, Jian R. Lu

We present a new particle tracking software algorithm designed to accurately track the motion of low-contrast particles against a background with large variations in light levels. The method is based on a polynomial fit of the intensity around each feature point, weighted by a Gaussian function of the distance from the centre, and is especially suitable for

Bernt Tore Jensen, Xiuping Su, Rupert W. T. Yu

In this paper, we study the set of $Δ$-filtered modules of quasi-hereditary algebras arising from quotients of the double of quivers of type $A$. Our main result is that for any fixed $Δ$-dimension vector, there is a unique (up to isomorphism) exceptional $Δ$-filtered module. We then apply this result to show that there is always an open adjoint orbit in the

M. J. Wright, S. Riedl, A. Altmeyer, C. Kohstall

We report on experimental studies on the collective behavior of a strongly interacting Fermi gas with tunable interactions and variable temperature. A scissors mode excitation in an elliptical trap is used to characterize the dynamics of the quantum gas in terms of hydrodynamic or near-collisionless behavior. We obtain a crossover phase diagram for collision

C. J. Efthimiou

The author&#39;s method (math-ph/9804010) that uses the Laplace transform to find exact values for a large class of convergent series is extended to trigonometric series.

Saul Rappaport, Josiah Schwab, Scott Burles

Using standard big-bang nucleosynthesis and present, high-precision measurements of light element abundances, we place constraints on the self-gravity of radiation pressure in the early universe. The self-gravity of pressure is strictly non-Newtonian, and thus the constraints we set are a direct test of this aspect of general relativity.

A. Aibéo, J. M. Ferreira, J. J. G. Lima

The concentration of magnetic flux near the poles of rapidly rotating cool stars has been recently proposed as an alternative mechanism to dynamo saturation in order to explain the saturation of angular momentum loss. In this work we study the effect of magnetic surface flux distribution on the coronal field topology and angular momentum loss rate. We invest

Chiranjib Sur, Rajat K Chaudhuri

We study the branching ratios of the allowed and forbidden radiative transitions among the first few (9) fine structure levels of O VI using relativistic coupled cluster theory. We find irregular patterns for a number of transitions with in $n$-complexes with $n\le4$. We have used the exisiting values of the allowed electric dipole ($E1$) transition as a ben

Chiranjib Sur, Rajat K Chaudhuri

In this article we study the effects of higher body excitations in the relativistic CC calculations for atoms and ions with one valence electron using Fock-space CCSD, CCSD(T) and its unitary variants. The present study demonstrates that CCSD(T) estimates the ionization potentials (IPs) and the valence electron removal energies quite accurately for alkali at

Steven Weber, Jeffrey G. Andrews, Nihar Jindal

This paper addresses three issues in the field of ad hoc network capacity: the impact of i)channel fading, ii) channel inversion power control, and iii) threshold-based scheduling on capacity. Channel inversion and threshold scheduling may be viewed as simple ways to exploit channel state information (CSI) without requiring cooperation across transmitters. W

Peter Landesman

A Galois theory of differential fields with parameters is developed in a manner that generalizes Kolchin&#39;s theory. It is shown that all connected differential algebraic groups are Galois groups of some appropriate differential field extension.

A. Maybhate, J. Masiero, J. E. Hibbard, J. C. Charlton

Super star clusters are young, compact star clusters found in the central regions of interacting galaxies. Recently, they have also been reported to preferentially form in certain tidal tails, but not in others. In this paper, we have used 21 cm HI maps and the Hubble Space Telescope Wide Field Planetary Camera 2 images of eight tidal tail regions of four me

Yuan Feng, Yaoyun Shi

Bennett et al. \cite{BDF+99} identified a set of orthogonal {\em product} states in the $3\otimes 3$ Hilbert space such that reliably distinguishing those states requires non-local quantum operations. While more examples have been found for this counter-intuitive ``nonlocality without entanglement&#39;&#39; phenomenon, a complete and computationally verifiab

S. Bellucci, P. Onorato

We propose a new scheme of spin filtering based on nanometric crossjunctions in the presence of Spin Orbit interaction, employing ballistic nanojunctions patterned in a two-dimensional electron gas. We demonstrate that the flow of a longitudinal unpolarized current through a ballistic X junction patterned in a two-dimensional electron gas with Spin Orbit cou

Ahmed Boucenna

The partisans of the hypothesis of the Indian origin of the numerals create confusion between the history of the Indian mathematics and the history of our modern numerals. To argue the thesis of the Indian origin of the numbers they confound between: the &#34;intuitive zero &#34; of Brahmagupta, that means &#39;&#39;nothing&#39;&#39; and which is the differe

N. V. Asari, R. Cid Fernandes, G. Stasinska, J. P. Torres-Papaqui

We study the evolution of 82302 star-forming (SF) galaxies from the SDSS. Our main goals are to explore new ways of handling star formation histories (SFH) obtained with our publicly available spectral synthesis code STARLIGHT, and apply them to investigate how SFHs vary as a function of nebular metallicity (Zneb). Our main results are: (1) A conventional co

Roman Gröger

In this Thesis we first show how the shape of the Peierls barrier and its dependence on the applied loading can be extracted from the data obtained in atomistic studies at 0 K. We consider the Peierls barrier as a two-dimensional periodic function of the position of the intersection of the dislocation line with the perpendicular {111} plane, with adjustable

Chiranjib Sur, Rajat K Chaudhuri

We report the forbidden $6s^{2} ^{1}S_{0}\longrightarrow6s5d ^{3}D_{1}$ magnetic-dipole transition amplitude computed using multi-reference Fock-space coupled-cluster theory. Our computed transition matrix element ($1.34\times10^{-4}μ_{B}$) is in excellent agreement with the experimental value ($1.33\times10^{-4}$ $μ_{B}$). This value in combination with oth

Philipp Mayr, Anne-Kathrin Walter

The paper discusses and analyzes the scientific search service Google Scholar (GS). The focus is on an exploratory study which investigates the coverage of scientific serials in GS. The study shows deficiencies in the coverage and up-to-dateness of the GS index. Furthermore, the study points up which Web servers are the most important data providers for this

Philippe Wenger, Damien Chablat, Félix Majou

This article presents the Orthoglide project. The purpose of this project is the realization of a prototype of machine tool to three degrees of translation. The characteristic of this machine is a parallel kinematic architecture optimized to obtain a compact workspace with homogeneous performance. For that, the principal criterion of design which was used is

J. Creel, J. Carmona-Reyes, J. Kong, Truell W. Hyde

Over the past decade, dust particulate contamination has increasingly become an area of concern within the fusion research community. In a burning plasma machine design like the International Thermonuclear Experimental Reactor (ITER), dust contamination presents problems for diagnostic integration and may contribute to tritium safety issues. Additionally due

J. Kong, T. Hyde, L. Matthews, M. Cook

Wakefield oscillations created by the ion wakefield existing below a dust particle within the plasma sheath generated above a powered lower electrode in a GEC rf reference cell carry information about the plasma sheath, the dust particle charge and the speed of the streaming ions. An experimental method to investigate such wakefield oscillations is discussed

S. Bellucci, P. Onorato

We discuss the Luttinger Liquid behaviour of Large Radius Carbon Nanotube e.g. the Multi Wall ones (MWNT), under the action of a transverse magnetic field $B$. Our results imply a reduction with $B$ in the value of the $bulk$ critical exponent, $α_{bulk}$, for the tunneling density of states, which is in agreement with that observed in transport experiments.

Hans-Ake Gustafsson

The Large Hadron Collider (LHC) will start operation in the end of 2007 colliding proton and lead beams at \surd S = 14 TeV and \surd S_{NN} = 5.5 TeV, respectively. The accelerator and the experiments are under construction and detailed studies of the physics program are being prepared. I will in this paper review the current status of the ALICE experiment

Gianluca Giovannetti, Serena Margadonna, Jeroen van den Brink

The electronic, magnetic and orbital structures of KCrF_3 are determined in all its recently identified crystallographic phases (cubic, tetragonal, and monoclinic) with a set of {\it ab initio} LSDA and LSDA+U calculations. The high-temperature undistorted cubic phase is metallic within the LSDA, but at the LSDA+U level it is a Mott insulator with a gap of 1

Damien Chablat, Philippe Wenger

The aim of this paper is to present a new six degree-of-freedom (dof) haptic device using two parallel mechanisms. The first one, called orthoglide, provides the translation motions and the second one produces the rotational motions. These two motions are decoupled to simplify the direct and inverse kinematics, as it is needed for real-times control. To redu

Fouad Bennis, Damien Chablat, Philippe Dépincé

Manufacturing is using Virtual Reality tools to enhance the product life cycle. Their definitions are still in flux and it is necessary to define their connections. Thus, firstly, we will introduce more closely some definitions where we will find that, if the Virtual manufacturing concepts originate from machining operations and evolve in this manufacturing

Antoine Rennuit, Alain Micaelli, Xavier Merlhiot, Claude Andriot

The animation of human avatars seems very successful; the computer graphics industry shows outstanding results in films everyday, the game industry achieves exploits... Nevertheless, the animation and control processes of such manikins are very painful. It takes days to a specialist to build such animated sequences, and it is not adaptive to any type of modi

Antoine Rennuit, Alain Micaelli, Xavier Merlhiot, Claude Andriot

The work presented here is aimed at introducing a virtual human controller in a virtual prototyping framework. After a brief introduction describing the problem solved in the paper, we describe the interest as for digital humans in the context of concurrent engineering. This leads us to draw a control architecture enabling to drive virtual humans in a real-t

Wilson Wong

This research hypothesized that a practical approach in the form of a solution framework known as Natural Language Understanding and Reasoning for Intelligence (NaLURI), which combines full-discourse natural language understanding, powerful representation formalism capable of exploiting ontological information and reasoning approach with advanced features, w

A. Russell, Vladimir I. Fal&#39;ko

We propose a kinetic theory to describe the power dependence, $I_{PC}(P)$, of the photocurrent (PC) lineshape in optically pumped quantum dots at low temperatures, in both zero and finite magnetic fields. We show that there is a crossover power $P_c$, determined by the electron and hole tunneling rates, at which the photocurrent spectra become strongly influ

H. N. Nazareno, P. E. de Brito, E. S. Rodrigues

In the present work we deal with the dynamics of wave packets in a two-dimensional crystal under the action of magnetic and electric fields. The magnetic field is perpendicular to the plane and the electric field is on the plane. In the simulations we considered a symmetric gauge for the vector potential while the initial wave packet was assumed to have a ga

Mazen Zein, Philippe Wenger, Damien Chablat

This paper analyses the workspace of the three-revolute orthogonal manipulators that have at least one of their DH parameters equal to zero. These manipulators are classified into different groups with similar kinematic properties. The classification criteria are based on the topology of the workspace. Each group is evaluated according to interesting kinemat

Maher Baili, Damien Chablat, Philippe Wenger

A family of 3R orthogonal manipulators without offset on the third body can be divided into exactly nine workspace topologies. The workspace is characterized in a half-cross section by the singular curves. The workspace topology is defined by the number of cusps and nodes that appear on these singular curves. Based on this classification, we evaluate theses

Damien Chablat, Philippe Wenger

This paper is devoted to the kinematic design of a new six degree-of-freedom haptic device using two parallel mechanisms. The first one, called orthoglide, provides the translation motions and the second one, called agile eye, produces the rotational motions. These two motions are decoupled to simplify the direct and inverse kinematics, as it is needed for r

Sudipto Paul Chowdhury

Computation of superstring partition function for the non-linear sigma model on the product of a two-torus and its dual within the scope of the doubled formalism is presented. We verify that it reproduces the partition functions of the toroidally compactified type--IIA and type--IIB theories for appropriate choices of the GSO projection.