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Arxiv.org
by George Kastrinakis
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In previous reports (arXiv:0901.2487, arXiv:1007.0745), we introduced a new fermionic variational wavefunction, suitable for interacting multi-species systems and sustaining superfluidity. This disentangled wavefunction contains a new quantum index. Here we introduce a general spin triplet version of this wavefunction.
Source: http://arxiv.org/abs/1007.3421v3
Arxiv.org
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We give a presentation of the centralizer algebras for tensor products of spinor representations of quantum groups via generators and relations. In the even-dimensional case, this can be described in terms of non-standard q-deformations of orthogonal Lie algebras; in the odd-dimensional case only a certain subalgebra will appear. In the classical case q = 1 the relations boil down to Lie algebra relations.
Source: http://arxiv.org/abs/1107.4183v2
Arxiv.org
by Nathan Cooper; James Bateman; Alexander Dunning; Tim Freegarde
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We demonstrate a simple and robust technique for removal of the carrier wave from a phase-modulated laser beam, using a non-interferometric method that is insensitive to the modulation frequency and instead exploits the polarization-dependence of electro-optic modulation. An actively stabilized system using feedback via a liquid crystal cell yields long-term carrier suppression in excess of 28 dB at the expense of a 6.5 dB reduction in sideband power.
Source: http://arxiv.org/abs/1203.3676v1
The melting of the magnetic vortex lattice has been observed in high-Tc superconductors in many experiments by different groups and is regarded as confirmed. To date, only one group claims to have observed the vortex-lattice melting in the low-Tc superconductor Nb3Sn in specific-heat measurements. We measured the same Nb3Sn single crystal with a differential-thermal analysis method. We report on the absence of any sign of vortex-lattice melting in our data and discuss the possible reasons for...
Source: http://arxiv.org/abs/1203.1848v2
Arxiv.org
by Stephen Serjeant
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Bright submm-selected galaxies have been found to be a rich source of strong gravitational lenses. However, strong gravitational lensing of extended sources leads inevitably to differential magnification. In this paper I quantify the effect of differential magnification on simulated far-infrared and submm surveys of strong gravitational lenses, using a foreground population of Navarro-Frenk-White plus de Vaucouleurs' density profiles, with a model source resembling the Cosmic Eyelash and QSO...
Source: http://arxiv.org/abs/1203.2647v2
Arxiv.org
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We propose a modified procedure for extracting the numerical value for the strong coupling constant $\alpha_s$ from the $\tau$ lepton hadronic decay rate into non-strange particles in the vector channel. We employ the concept of the quark-hadron duality specifically, introducing a boundary energy squared $s_{\rm p}>0$, the onset of the perturbative QCD continuum in Minkowski space \cite{BLR,Rafa,PPR}. To approximate the hadronic spectral function in the region $s>s_{\rm p}$, we use...
Source: http://arxiv.org/abs/1005.2674v3
Arxiv.org
by Tankut Can; Hui Dai; Dirk K. Morr
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Using the non-equilibrium Keldysh Green's function formalism, we show that the non-equilibrium charge transport in nanoscopic quantum networks takes place via {\it current eigenmodes} that possess characteristic spatial patterns. We identify the microscopic relation between the current patterns and the network's electronic structure and topology and demonstrate that these patterns can be selected via gating or constrictions, providing new venues for manipulating charge transport at the...
Source: http://arxiv.org/abs/1203.3198v1
Arxiv.org
by Robert F. Bailey; José Cáceres; Delia Garijo; Antonio González; Alberto Márquez; Karen Meagher; María Luz Puertas
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A set of vertices $S$ in a graph $G$ is a {\em resolving set} for $G$ if, for any two vertices $u,v$, there exists $x\in S$ such that the distances $d(u,x) \neq d(v,x)$. In this paper, we consider the Johnson graphs $J(n,k)$ and Kneser graphs $K(n,k)$, and obtain various constructions of resolving sets for these graphs. As well as general constructions, we show that various interesting combinatorial objects can be used to obtain resolving sets in these graphs, including (for Johnson graphs)...
Source: http://arxiv.org/abs/1203.2660v2
Arxiv.org
by Per Berglund; Jishnu Bhattacharyya; David Mattingly
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We study electromagnetically charged dilatonic black brane solutions in arbitrary dimensions with flat transverse spaces, that are asymptotically AdS. This class of solutions includes spacetimes which possess a bulk region where the metric is approximately invariant under Lifshitz scalings. Given fixed asymptotic boundary conditions, we analyze how the behavior of the bulk up to the horizon varies with the charges and derive the extremality conditions for these spacetimes.
Source: http://arxiv.org/abs/1107.3096v2
Arxiv.org
by R. Parthasarathy
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The apparent violation of causality in the brane Universe can be avoided by taking the bulk spacetime modelled by a 5-dimensional Kaluza theory with factorizable ansatz for the 5-dimensional metric whose components do not depend on the fifth coordinate and with $G_{55}$ not a constant. The geodesic in the bulk does not correspond to a free particle. The Kaluza scalar makes it non-inertial. The implication on the neutrino experiment is that there is no superluminal propagation even after...
Source: http://arxiv.org/abs/1203.6192v1
Arxiv.org
by Friedrich Götze; Andrei Yu. Zaitsev
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The aim of this paper is to investigate, which infinite dimensional consequences follow from the main results of recently published paper of the authors (2009) (see Theorems 2 and 3). We show that the finite dimensional Theorem 3 implies meaningful estimates for the rate of strong Gaussian approximation of sums of i.i.d. Hilbert space valued random vectors $\xi_j$ with finite moments $E |\xi_j|^\gamma$, $\gamma>2$. We show that the rate of approximation depends substantially on the rate of...
Source: http://arxiv.org/abs/1203.5695v1
Arxiv.org
by Luke Barclay; Ruth Gregory; Susha Parameswaran; Gianmassimo Tasinato; Ivonne Zavala
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We compute string theoretic black hole solutions having Lifshitz asymptotics with a general dynamical exponent z>1. We start by constructing solutions in a flux compactification of six dimensional supergravity, then uplift them to massive type IIA supergravity. Alongside the Lifshitz black holes we study the simpler anti-de Sitter solutions, of which there are a 1-parameter family in this supergravity, and compare and contrast their properties. The black holes are characterized by a two-form...
Source: http://arxiv.org/abs/1203.0576v2
Arxiv.org
by Yoichi Motohashi
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This is my talk delivered at the workshop 'Automorphic L-Functions and related prpblems' (March 10--13, 2012, Tokyo University). We showed an instance of applications of the theory of automorphic representations to a genuinely traditional problem in the theory of the zeta and allied functions. We restricted ourselves to very basic issues and results, because of the purpose of the workshop.
Source: http://arxiv.org/abs/1203.2694v1
Arxiv.org
by Franco Buccella; Domenico Falcone; Chee Sheng Fong; Enrico Nardi; Giulia Ricciardi
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We consider the see-saw mechanism within a non-supersymmetric SO(10) model. By assuming the SO(10) quark-lepton symmetry, and after imposing suitable conditions that ensure that the right-handed (RH) neutrino masses are at most mildly hierarchical (compact RH spectrum) we obtain a surprisingly predictive scenario. The absolute neutrino mass scale, the Dirac and the two Majorana phases of the neutrino mixing matrix remain determined in terms of the set of already measured low energy observables,...
Source: http://arxiv.org/abs/1203.0829v2
Arxiv.org
by Subhamoy Ghatak; Atindra Nath Pal; Arindam Ghosh
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We present low temperature electrical transport experiments in five field effect transistor devices consisting of monolayer, bilayer and trilayer MoS2 films, mechanically exfoliated onto Si/SiO2 substrate. Our experiments reveal that the electronic states in all films are localized well up to the room temperature over the experimentally accessible range of gate voltage. This manifests in two dimensional (2D) variable range hopping (VRH) at high temperatures, while below \sim 30 K the...
Source: http://arxiv.org/abs/1203.5656v1
Arxiv.org
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Random coding, along with various standard techniques such as coded time-sharing, rate-splitting, superposition coding, and binning, are traditionally used in obtaining achievable rate regions for multi-terminal networks. The error analysis of such an achievable scheme relies heavily on the properties of strongly joint typical sequences and on bounds of the cardinality of typical sets. In this work, we obtain an achievable rate region for a general (i.e. an arbitrary set of messages shared...
Source: http://arxiv.org/abs/1107.4705v2
Arxiv.org
by Mitsuyasu Hashimoto
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Let $p$ be a prime number. We define the notion of $F$-finiteness of homomorphisms of $\mathbb F_p$-algebras, and discuss some basic properties. In particular, we prove a sort of descent theorem on $F$-finiteness of homomorphisms of $\mathbb F_p$-algebras. As a corollary, we prove the following. Let $g:B\to C$ be a homomorphism of Noetherian $\mathbb F_p$-algebras. If $g$ is faithfully flat reduced, and $C$ is $F$-finite, then $B$ is $F$-finite. This is a generalization of Seydi's result on...
Source: http://arxiv.org/abs/1203.3640v2
Arxiv.org
by Satoshi Takagi
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In this paper, we introduce a new algebraic type of `convexoid rings', and we give the definition of (weak) convexoid schemes, which share similar properties with ordinary schemes. As a result, we give a purely-algebraic construction of the compactification of Spec Z (in Arakelov's sense) which is realized as the Zariski-Riemann space in the category of weak convexoid schemes.
Source: http://arxiv.org/abs/1203.4914v2
Arxiv.org
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A nonlinear electromagnetic scattering problem is studied in the presence of bound states in the radiation continuum. It is shown that the solution is not analytic in the nonlinear susceptibility and the conventional perturbation theory fails. A non-perturbative approach is proposed and applied to the system of two parallel periodic arrays of dielectric cylinders with a second order nonlinear susceptibility. This scattering system is known to have bound states in the radiation continuum. In...
Source: http://arxiv.org/abs/1107.0468v2
Arxiv.org
by S. H. P. Alencar; J. Bouvier; F. M. Walter; C. Dougados; J. -F. Donati; R. Kurosawa; M. Romanova; X. Bonfils; G. H. R. A. Lima; S. Massaro; M. Ibrahimov; E. Poretti
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We analyze the photometric and spectroscopic variability of the classical T Tauri star V2129 Oph over several rotational cycles to test the dynamical predictions of magnetospheric accretion models. The photometric variability and the radial velocity variations in the photospheric lines can be explained by rotational modulation due to cold spots, while the radial velocity variations of the He I (5876 \AA) line and the veiling variability are due to hot spot rotational modulation. The hot and...
Source: http://arxiv.org/abs/1203.6331v1
Arxiv.org
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We realize the integral Specht modules for the symmetric group $S_n$ as induced modules from the subalgebra of the group algebra generated by the Jucys-Murphy elements. We deduce from this that the simple modules for $FS_n$ are generated by reductions modulo $p$ of the corresponding Jucys-Murphy idempotents.
Source: http://arxiv.org/abs/1107.3076v3
Arxiv.org
by Yi Huang
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We prove a McShane-type identity - a series, expressed in terms of geodesic lengths, that sums to 2\pi for any closed hyperbolic surface with one distinguished point. To do so, we prove a generalized Birman-Series theorem showing that the set of complete geodesics on a hyperbolic surface with large cone angles is sparse.
Source: http://arxiv.org/abs/1203.3860v4
Arxiv.org
by C. S. Lopez-Monsalvo; F. Nettel; A. Sanchez
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We comment on the conclusions found by Larra\~naga and Mojica regarding the consistency of the Geoemtrothermodynamics programme to describe the critical behaviour of a Gibbons-Maeda-Garfinkle-Horowitz-Strominger charged black hole. We argue that making the appropriate choice of metric for the thermodynamic phase space and, most importantly, considering the homogeneity of the thermodynamic potential we obtain consistent results for such a black hole.
Source: http://arxiv.org/abs/1203.6444v1
Arxiv.org
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We consider perturbations of Dirac type operators on complete, connected metric spaces equipped with a doubling measure. Under a suitable set of assumptions, we prove quadratic estimates for such operators and hence deduce that these operators have a bounded functional calculus. In particular, we deduce a Kato square root type estimate.
Source: http://arxiv.org/abs/1107.3905v2
Arxiv.org
by M. Berciu; R. Chakarvorty; Y. Y. Zhou; M. T. Alam; K. Traudt; R. Jakiela; A. Barcz; T. Wojtowicz; X. Liu; J. K. Furdyna; M. Dobrowolska
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We present a unified interpretation of experimentally observed magnetic circular dichroism (MCD) in the ferromagnetic semiconductor (Ga,Mn)As, based on theoretical arguments, which demonstrates that MCD in this material arises primarily from a difference in the density of spin-up and spin-down states in the valence band brought about by the presence of the Mn impurity band, rather than being primarily due to the Zeeman splitting of electronic states.
Source: http://arxiv.org/abs/1203.1853v1
Arxiv.org
by Gil R. Cavalcanti
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We use the procedure of reduction of Courant algebroids to reduce strong KT, hyper KT and generalized Kaehler structures on Courant algebroids. This allows us to recover results from the literature as well as explain from a different angle some of the features observed there in. As an example, we prove that the moduli space of instantons of a bundle over a SKT/HKT/generalized K\"ahler manifold is endowed with the same type of structure as the original manifold.
Source: http://arxiv.org/abs/1203.0497v1
Arxiv.org
by B. Parise; F. Du; F. -C. Liu; A. Belloche; H. Wiesemeyer; R. Güsten; K. M. Menten; H. W. Hübers; B. Klein
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Although water is an essential and widespread molecule in star-forming regions, its chemical formation pathways are still not very well constrained. Observing the level of deuterium fractionation of OH, a radical involved in the water chemical network, is a promising way to infer its chemical origin. We aim at understanding the formation mechanisms of water by investigating the origin of its deuterium fractionation. This can be achieved by observing the abundance of OD towards the low-mass...
Source: http://arxiv.org/abs/1203.2825v1
Arxiv.org
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We investigate femtoscopic $\pi \pi$ correlations using the UrQMD approach combined with a correlation afterburner. The dependence of $\pi \pi$ correlations on the charged particle multiplicity and formation time in p+p collisions at $\sqrt{s_{NN}}$= 7 TeV is explored and compared to present ALICE data. The data allows to constrain the formation time in the string fragmentation to $\tau_f \leq 0.8$ fm/c.
Source: http://arxiv.org/abs/1203.4421v1
Arxiv.org
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Mishchenko's theorem states that piecewise smooth and Lie algebroid cohomology of a transitive Lie algebroid defined over a combinatorial manifold are isomorphic. In this paper, we describe two applications of that result. The first application consists in the relationship between piecewise de Rham cohomology of a Lie groupoid and piecewise smooth cohomology of its Lie algebroid. For the second application, we combine the classical result dealing with invariant cohomology in Lie algebroids with...
Source: http://arxiv.org/abs/1203.6699v1
Arxiv.org
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We analyze gradient flows with jumps generated by a finite set of complete vector fields in involution using some Radon measures $u\in \mathcal{U}_a$ as admissible perturbations. Both the evolution of a bounded gradient flow $\{x^u(t,\l)\in B(x^*,3\g)\subseteq \mbn: \,t\in[0,T],\,\l\in B(x^*,2\g)\}$ and the unique solution $\l=\psi^u(t,x)\in B(x^*,2\g)\subseteq \mbn$ of integral equation $x^u(t,\l)=x\in B(x^*,\g), \,t\in[0,T]$, are described using the corresponding gradient representation...
Source: http://arxiv.org/abs/1203.1741v1
Arxiv.org
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We prove a formal power series identity, relating the arithmetic sum-of-divisors function to commuting triples of permutations. This establishes a conjecture of Franklin T. Adams-Watters.
Source: http://arxiv.org/abs/1203.5079v1
Arxiv.org
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The secondary-to-primary B/C ratio is widely used to study the cosmic ray (CR) propagation processes in the Galaxy. It is usually assumed that secondary nuclei such as Li-Be-B are entirely generated by collisions of heavier CR nuclei with the interstellar medium (ISM). We study the CR propagation under a scenario where secondary nuclei can also be produced or accelerated from galactic sources. We consider the processes of hadronic interactions inside supernova remnants (SNRs) and...
Source: http://arxiv.org/abs/1203.6094v2
Arxiv.org
by Andreas Andresen; Peter Imkeller; Nicolas Perkowski
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Ciesielski's isomorphism between the space of alpha-H\"older continuous functions and the space of bounded sequences is used to give an alternative proof of the large deviation principle for Wiener processes with values in Hilbert space.
Source: http://arxiv.org/abs/1203.4596v1
Arxiv.org
by Sonia De Cosmis; Renato De Leone
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The concepts of infinity and infinitesimal in mathematics date back to anciens Greek and have always attracted great attention. Very recently, a new methodology has been proposed by Sergeyev for performing calculations with infinite and infinitesimal quantities, by introducing an infinite unit of measure expressed by the numeral grossone. An important characteristic of this novel approach is its attention to numerical aspects. In this paper we will present some possible applications and use of...
Source: http://arxiv.org/abs/1107.5681v2
Arxiv.org
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Kagan and Shepp (2005, Amer. Statist.) presented an elegant example of a mixture model for which an insufficient statistic preserves Fisher information. This note uses the regularity property of differentiability in quadratic mean to provide another explanation for the phenomenon they observed. Some connections with Le Cam's theory for convergence of experiments are noted.
Source: http://arxiv.org/abs/1107.3797v2
Arxiv.org
by Mingxing Luo; Liucheng Wang; Guohuai Zhu
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By using recent data, we directly determine the dark matter (DM) induced $e^\pm$ spectrum at the source from experimental measurements at the earth, without reference to specific particle physics models. The DM induced gamma rays emitted via inverse Compton scattering are then obtained in a model independent way. However the results depend on the choice of the astrophysical $e^\pm$ background, which is not reliably known. Nevertheless, we calculate, as an illustration, the fluxes of gamma rays...
Source: http://arxiv.org/abs/1107.3024v4
Arxiv.org
by Holger Brenner; Axel Stäbler
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Let $Y \to B$ be a relative smooth projective curve over an affine integral base scheme $B$ of positive characteristic. We provide for all prime characteristics example classes of vector bundles $\mathcal{S}$ over $Y$ such that $\mathcal{S}$ is generically strongly semistable and semistable but not strongly semistable for some special fibre. This also provides new examples of the behaviour of Hilbert-Kunz multiplicities in geometric families.
Source: http://arxiv.org/abs/1107.0877v4
A corrector theory for the strong approximation of gradient fields inside periodic composites made from two materials with different power law behavior is provided. Each material component has a distinctly different exponent appearing in the constitutive law relating gradient to flux. The correctors are used to develop bounds on the local singularity strength for gradient fields inside micro-structured media. The bounds are multi-scale in nature and can be used to measure the amplification of...
Source: http://arxiv.org/abs/1107.3181v2
Arxiv.org
by R. Margutti; E. Zaninoni; M. G. Bernardini; G. Chincarini; F. Pasotti; C. Guidorzi; L. Angelini; D. N. Burrows; M. Capalbi; P. A. Evans; N. Gehrels; J. Kennea; V. Mangano; A. Moretti; J. Nousek; J. P. Osborne; K. L. Page; M. Perri; J. Racusin; P. Romano; B. Sbarufatti; S. Stafford; M. Stamatikos
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We present a comprehensive statistical analysis of Swift X-ray light-curves of Gamma-Ray Bursts (GRBs) collecting data from more than 650 GRBs discovered by Swift and other facilities. The unprecedented sample size allows us to constrain the REST FRAME X-ray properties of GRBs from a statistical perspective, with particular reference to intrinsic time scales and the energetics of the different light-curve phases in a common rest-frame 0.3-30 keV energy band. Temporal variability episodes are...
Source: http://arxiv.org/abs/1203.1059v2
Arxiv.org
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Fermion production in an external Coulomb field on de Sitter expanding universe is studied. The amplitude and probability of pair production in an external Coulomb field are computed and the cases of large/small values of the expansion factor comparatively with the particle mass are studied. We obtain from our calculations that the modulus of the momentum is no longer a conserved quantity. We find that in the de Sitter space there are probabilities for production processes where the helicity is...
Source: http://arxiv.org/abs/1203.0151v1
Arxiv.org
by H. F. Chau; C. -K. Li; Y. -T. Poon; N. -S. Sze
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Recently, Chau [Quant. Inform. & Comp. 11, 721 (2011)] showed that one can define certain metrics and pseudo-metrics on U(n), the group of all $n\times n$ unitary matrices, based on the arguments of the eigenvalues of the unitary matrices. More importantly, these metrics and pseudo-metrics have quantum information theoretical meanings. So it is instructive to study this kind of metrics and pseudo-metrics on U(n). Here we show that any symmetric norm on ${\mathbb R}^n$ induces a metric on...
Source: http://arxiv.org/abs/1107.1047v2
Arxiv.org
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We study the dynamics of galactic disk formation and evolution in 'realistic' LambdaCDM haloes with idealized baryonic initial conditions. We add rotating spheres of hot gas at z=1.3 to two fully cosmological dark-matter-only halo (re)simulations. The gas cools according to an artificial and adjustable cooling function to form a rotationally supported galaxy. The simulations evolve in the full cosmological context until z=0. We vary the angular momentum and density profiles of the initial gas...
Source: http://arxiv.org/abs/1203.1190v2
Arxiv.org
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In this paper we obtain new properties of a signal generated by the Riemann zeta-function on the critical line. At the same time we obtain an asymptotic formula for a new class of transcendental integrals connected with the Riemann zeta-function.
Source: http://arxiv.org/abs/1203.0159v1
Arxiv.org
by Weiyu Xu; Alex Dimakis; Babak Hassibi
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In this paper, we study the mixing time of Markov Chain Monte Carlo (MCMC) for integer least-square (LS) optimization problems. It is found that the mixing time of MCMC for integer LS problems depends on the structure of the underlying lattice. More specifically, the mixing time of MCMC is closely related to whether there is a local minimum in the lattice structure. For some lattices, the mixing time of the Markov chain is independent of the signal-to-noise ($SNR$) ratio and grows polynomially...
Source: http://arxiv.org/abs/1203.2213v1
Arxiv.org
by H. Bruntt; S. Basu; B. Smalley; W. J. Chaplin; G. A. Verner; T. R. Bedding; C. Catala; J. -C. Gazzano; J. Molenda-Zakowicz; A. O. Thygesen; K. Uytterhoeven; S. Hekker; D. Huber; C. Karoff; S. Mathur; B. Mosser; T. Appourchaux; T. L. Campante; Y. Elsworth; R. A. Garcia; R. Handberg; T. S. Metcalfe; P. -O. Quirion; C. Regulo; I. W. Roxburgh; D. Stello; J. Christensen-Dalsgaard; S. D. Kawaler; H. Kjeldsen; R. L. Morris; E. V. Quintana; D. T. Sanderfer
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We present a detailed spectroscopic study of 93 solar-type stars that are targets of the NASA/Kepler mission and provide detailed chemical composition of each target. We find that the overall metallicity is well-represented by Fe lines. Relative abundances of light elements (CNO) and alpha-elements are generally higher for low-metallicity stars. Our spectroscopic analysis benefits from the accurately measured surface gravity from the asteroseismic analysis of the Kepler light curves. The log g...
Source: http://arxiv.org/abs/1203.0611v1
Arxiv.org
by Sebastian Casalaina-Martin; Radu Laza
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A key tool in the study of algebraic surfaces and their moduli is Brieskorn's simultaneous resolution for families of algebraic surfaces with simple (du Val or ADE) singularities. In this paper we show that a similar statement holds for families of curves with at worst simple (ADE) singularities. For a family $\mathscr X\to B$ of ADE curves, we give an explicit and natural resolution of the rational map $B\to \bar M_g$. Moreover, we discuss a lifting of this map to the moduli stack $ \bar...
Source: http://arxiv.org/abs/1007.0265v2
Arxiv.org
by Mugurel Ţolea; Bogdan Ostahie; Marian Niţă; Felicia Ţolea; Alexandru Aldea
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The phase of the electronic wave function is not directly measurable but, quite remarkably, it becomes accessible in pairs of isospectral shapes, as recently proposed in the experiment of Christopher R. Moon {\it et al.}, Science {\bf 319}, 782 (2008). The method is based on a special property, called transplantation, which relates the eigenfunctions of the isospectral pairs, and allows to extract the phase distributions, if the amplitude distributions are known. We numerically simulate such a...
Source: http://arxiv.org/abs/1203.0717v1
Arxiv.org
by César Ayala; Carlos Contreras; Gorazd Cvetič
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In contrast to perturbative QCD, the analytic QCD models have running coupling whose analytic properties correctly mirror those of spacelike observables. The discontinuity (spectral) function of such running coupling is expected to agree with the perturbative case at large timelike momenta; however, at low timelike momenta it is not known. In the latter regime, we parametrize the unknown behavior of the spectral function as a sum of (two) delta functions; while the onset of the perturbative...
Source: http://arxiv.org/abs/1203.6897v2
Arxiv.org
by E. R. Bezerra de Mello; A. A. Saharian
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We investigate the Wightman function, the vacuum expectation values of the field squared and the energy-momentum tensor for a massive scalar field with general curvature coupling in the generalized cosmic string geometry with a compact dimension along its axis. The boundary condition along the compactified dimension is taken in general form with an arbitrary phase. The vacuum expectation values are decomposed into two parts. The first one corresponds to the uncompactified cosmic string geometry...
Source: http://arxiv.org/abs/1107.2557v2
Arxiv.org
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In a central potential the usual resolution of the Schr\"odinger equation in spherical coordinates consists in determining the solutions R(r) or u(r) of the radial equations considered as the radial parts of the Schr\"odinger equation. However, the solutions must be supplemented with the boundary condition u(0) = 0 in order to rule out singular solutions. There is still no consensus to justify this condition, with good reason. It is based on a misunderstanding that comes from the fact...
Source: http://arxiv.org/abs/1203.0551v1
Arxiv.org
by Casper Drukier; Lorenz Bartosch; Aldo Isidori; Peter Kopietz
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Using functional renormalization group methods, we study an effective low-energy model describing the Ising-nematic quantum critical point in two-dimensional metals. We treat both gapless fermionic and bosonic degrees of freedom on equal footing and explicitly calculate the momentum and frequency dependent effective interaction between the fermions mediated by the bosonic fluctuations. Following earlier work by S.-S. Lee for a one-patch model, Metlitski and Sachdev [Phys. Rev. B {\bf{82}},...
Source: http://arxiv.org/abs/1203.2645v2
Arxiv.org
by A. Fête; S. Gariglio; A. D. Caviglia; J. -M. Triscone; M. Gabay
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We report measurements of the normal state in-plane magnetoconductance in gated LaAlO$_3$-SrTiO$_3$ samples. As the orientation of the magnetic field changes within the plane of the interface, the signal displays periodic oscillations with respect to the angle between the field and the direction of the current. We show that in the underdoped to optimally doped range, a Fermi surface reconstruction takes place due to the Rashba spin-orbit term and that the oscillations are due to a magnetic...
Source: http://arxiv.org/abs/1203.5239v2
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by Michele Cicoli; Anshuman Maharana; F. Quevedo; C. P. Burgess
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We consider a novel scenario for modulus stabilisation in IIB string compactifications in which the Kahler moduli are stabilised by a general set-up with two kinds of non-perturbative effects: (i) standard Kahler moduli-dependent non-perturbative effects from gaugino condensation on D7-branes or E3-instantons wrapping four-cycles in the geometric regime; (ii) dilaton-dependent non-perturbative effects from gaugino condensation on space-time filling D3-branes or E(-1)-instantons at...
Source: http://arxiv.org/abs/1203.1750v2
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by Lei Li; Sihai Zhang; Kaiwei Wang; Wuyang Zhou
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In cognitive radio networks, channel aggregation (CA) and channel fragmentation (CF) techniques have been proposed to enhance the spectrum utilization. While most of the literature studies CA and CF independently, in this paper we combine CA and CF innovatively and present a new spectrum sharing strategy named CAF (Channel Aggregation and Fragmentation). We elaborate on the proposed CAF strategy and derive the balance equation by a continuous time Markov chain (CTMC) model. Then various system...
Source: http://arxiv.org/abs/1203.4913v2
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by I. Gonzalez; A. Deppman; S. Duarte; F. Krmpotić; M. S. Hussein; C. Barbero
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We study the nonmesonic weak decay (NMWD) $\Lambda N \to nN$ of the ${}^{12}_{\Lambda} C$ hypernucleus induced by the nucleon $N=n,p$ with transition rate $\Gamma_N$. The nuclear process is described by the interplay of two models; one describing the NMWD of hyperon $\Lambda$ in the nuclear environment, and the other taking into account the Final State Interaction (FSI) of the two outgoing nucleons with the residual nucleus. The first one is done in the framework of the Independent-Particle...
Source: http://arxiv.org/abs/1203.3214v1
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In this paper, we prove that the inverse problems for 2D elasticity and for the thin plate with boundary data (finite or full measurements) are equivalent. Having proved this equivalence, we can solve inverse problems for the plate equation with boundary data by solving the corresponding inverse problems for 2D elasticity, and vice versa. For example, we can derive bounds on the volume fraction of the two-phase thin plate from the knowledge of one pair of boundary measurements using the known...
Source: http://arxiv.org/abs/1203.3833v1
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by Chung-Hsing Chen; Wen-Chi Su; Chih-Yu Chen; Jing-Ying Huang; Fang-Yu Tsai; Wen-Chang Wang; Chao A. Hsiung; King-Song Jeng; I-Shou Chang
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RNA interference (RNAi) is an endogenous cellular process in which small double-stranded RNAs lead to the destruction of mRNAs with complementary nucleoside sequence. With the production of RNAi libraries, large-scale RNAi screening in human cells can be conducted to identify unknown genes involved in a biological pathway. One challenge researchers face is how to deal with the multiple testing issue and the related false positive rate (FDR) and false negative rate (FNR). This paper proposes a...
Source: http://arxiv.org/abs/1203.4445v1
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by Sophie J. Underwood; Joel Giedt; Anthony W. Thomas; Ross D. Young
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We provide a scan of the parameter space for neutralino-hadron scattering in the next-to-minimal supersymmetric standard model using an updated value for the strange quark sigma commutator. These results also take into account constraints from WMAP data on the relic density and new constraints from the Large Hadron Collider. We find that the resultant spin-independent cross sections are smaller in magnitude than those found in recent results obtained within the constrained minimal...
Source: http://arxiv.org/abs/1203.1092v1
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Magnetic Resonance Imaging (MRI) is one of the fields that the compressed sensing theory is well utilized to reduce the scan time significantly leading to faster imaging or higher resolution images. It has been shown that a small fraction of the overall measurements are sufficient to reconstruct images with the combination of compressed sensing and parallel imaging. Various reconstruction algorithms has been proposed for compressed sensing, among which Augmented Lagrangian based methods have...
Source: http://arxiv.org/abs/1203.4587v1
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by Alexandre Lung-Yut-Fong; Céline Lévy-Leduc; Olivier Cappé
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Detecting and locating changes in highly multivariate data is a major concern in several current statistical applications. In this context, the first contribution of the paper is a novel non-parametric two-sample homogeneity test for multivariate data based on the well-known Wilcoxon rank statistic. The proposed two-sample homogeneity test statistic can be extended to deal with ordinal or censored data as well as to test for the homogeneity of more than two samples. The second contribution of...
Source: http://arxiv.org/abs/1107.1971v3
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Galaxy groups are the least massive systems where the bulk of baryons begin to be accounted for. Not simply the scaled-down versions of rich clusters following self-similar relations, galaxy groups are ideal systems to study baryon physics, which is important for both cluster cosmology and galaxy formation. We review the recent observational results on the hot gas in galaxy groups. The first part of the paper is on the scaling relations, including X-ray luminosity, entropy, gas fraction, baryon...
Source: http://arxiv.org/abs/1203.4228v1
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by Jacek Graczyk; Peter W. Jones; Nicolae Mihalache
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We study lower and upper bounds of the Hausdorff dimension for sets which are wiggly at scales of positive density. The main technical ingredient is a construction, for every continuum K, of a Borel probabilistic measure \mu with the property that on every ball B(x,r), with x in K, the measure is bounded by a universal constant multiple of r\exp(-g(x,r)), where g(x,r) > 0 is an explicit function. The continuum K is mean wiggly at exactly those points x in K where g(x, r) has a logarithmic...
Source: http://arxiv.org/abs/1203.6501v1
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In this note we review the construction of topologically gauged M2 branes with 6 supersymmetries and discuss some of its properties. This is done using the 3-algebra formulation thereby covering all possible gauge groups. We will elaborate upon 1) the fundamental identity and its solutions noting, provided these gauged theories describe stacks of branes, the case of a single brane, 2) the chiral point solution to the field equations (occuring even for a single brane) that breaks the...
Source: http://arxiv.org/abs/1203.5090v1
Arxiv.org
by K. Arisaka; P. Beltrame; C. W. Lam; P. F. Smith; C. Ghag; D. B. Cline; K. Lung; Y. Meng; E. Pantic; P. R. Scovell; A. Teymourian; H. Wang
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We study a three stage dark matter and neutrino observatory based on multi-ton two-phase liquid Xe and Ar detectors with sufficiently low backgrounds to be sensitive to WIMP dark matter interaction cross sections down to 10E-47 cm^2, and to provide both identification and two independent measurements of the WIMP mass through the use of the two target elements in a 5:1 mass ratio, giving an expected similarity of event numbers. The same detection systems will also allow measurement of the pp...
Source: http://arxiv.org/abs/1107.1295v3
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by I. P. Ivanov; V. Keus
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In many models, stability of dark matter particles is protected by a conserved Z_2 quantum number. However dark matter can be stabilized by other discrete symmetry groups, and examples of such models with custom-tailored field content have been proposed. Here we show that electroweak symmetry breaking models with N Higgs doublets can readily accommodate scalar dark matter candidates stabilized by groups Z_p with any $p \le 2^{N-1}$, leading to a variety of kinds of microscopic dynamics in the...
Source: http://arxiv.org/abs/1203.3426v1
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by Ralf Aurich; Sven Lustig
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The cosmic microwave background (CMB) anisotropy possesses the remarkable property that its power is strongly suppressed on large angular scales. This observational fact can naturally be explained by cosmological models with a non-trivial topology. The paper focuses on lens spaces L(p,q) which are realised by a tessellation of the spherical 3-space S^3 by cyclic deck groups of order p = 60^\circ suppressed by a factor of two compared to the simply connected S^3 space. The analysis is based on...
Source: http://arxiv.org/abs/1203.4086v2
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by Abhishek Shukla; T. S. Mahesh
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We describe a method for quantitative characterization of radio-frequency (RF) inhomogeneity using NOON states. NOON states are special multiple-quantum coherences which can be easily prepared in star-topology spin-systems. In this method we exploit the high sensitivity of the NOON states for z-rotations. As a result, Torrey oscillations with NOON states decay much faster than that of single quantum coherences. Therefore the present method requires shorter pulse durations, and enables the study...
Source: http://arxiv.org/abs/1203.4414v1
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by M. Arrayás; M. A. Fontelos; U. Kindelán
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We present the first analytical and numerical studies of the initial stage of the branching process based on an interface dynamics streamer model in the fully 3-D case. This model follows from fundamental considerations on charge production by impact ionization and balance laws, and leads to an equation for the evolution of the interface between ionized and non-ionized regions. We compare some experimental patterns with the numerically simulated ones, and give an explicit expression for the...
Source: http://arxiv.org/abs/1203.6790v1
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by A. Maleknejad; M. M. Sheikh-Jabbari
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In this work we revisit Wald's cosmic no-hair theorem in the context of accelerating Bianchi cosmologies for a generic cosmic fluid with non-vanishing anisotropic stress tensor and when the fluid energy momentum tensor is of the form of a cosmological constant term plus a piece which does not respect strong or dominant energy conditions. Such a fluid is the one appearing in inflationary models. We show that for such a system anisotropy may grow, in contrast to the cosmic no-hair conjecture. In...
Source: http://arxiv.org/abs/1203.0219v2
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by Kevin Heng; Pushkar Kopparla
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We investigate the stability of super Earth atmospheres around M stars using a 7-parameter, analytical framework. We construct stability diagrams in the parameter space of exoplanetary radius versus semi-major axis and elucidate the regions in which the atmospheres are stable against the condensation of their major constituents, out of the gas phase, on their permanent nightside hemispheres. We find that super Earth atmospheres which are nitrogen-dominated ("Earth-like") occupy a...
Source: http://arxiv.org/abs/1203.1922v3
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by Yuri Kharlov; for the ALICE collaboration
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The ALICE experiment at the LHC has collected wealthy data in proton-proton and lead-lead collisions. An overview of recent ALICE results is given in this paper. Hadron spectra measured in pp collisions at $\sqrt{s}=0.9$, 2.76 and 7 TeV are discussed. Properties of hot nuclear matter produced in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV, revealed via many observables measured with the ALICE experiment, are shown.
Source: http://arxiv.org/abs/1203.2420v1
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by M. F. Cornelio; O. Jiménez Farías; F. F. Fanchini; I. Frerot; G. H. Aguilar; M. O. Hor-Meyll; M. C. de Oliveira; S. P. Walborn; A. O. Caldeira; P. H. Souto Ribeiro
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We use the classical correlation between a quantum system being measured and its measurement apparatus to analyze the amount of information being retrieved in a quantum measurement process. Accounting for decoherence of the apparatus, we show that these correlations may have a sudden transition from a decay regime to a constant level. This transition characterizes a non-asymptotic emergence of the pointer basis, while the system-apparatus can still be quantum correlated. We provide a...
Source: http://arxiv.org/abs/1203.5068v2
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by Benjamin C. Bromley; Scott J. Kenyon; Margaret J. Geller; Warren R. Brown
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We examine whether disrupted binary stars can fuel black hole growth. In this mechanism, tidal disruption produces a single hypervelocity star (HVS) ejected at high velocity and a former companion star bound to the black hole. After a cluster of bound stars forms, orbital diffusion allows the black hole to accrete stars by tidal disruption at a rate comparable to the capture rate. In the Milky Way, HVSs and the S star cluster imply similar rates of 10^{-5}--10^{-3} yr^{-1} for binary...
Source: http://arxiv.org/abs/1203.6685v1
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by J. de la Cruz Rodríguez; H. Socas-Navarro; M. Carlsson; J. Leenaarts
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The magnetic field of the quiet-Sun chromosphere remains a mystery for solar physicists. The reduced number of chromospheric lines are intrinsically hard to model and only a few of them are magnetically sensitive. In this work, we use a 3D numerical simulation of the outer layers of the solar atmosphere, to asses the reliability of non-LTE inversions, in this case applied to the Ca II 8542 \AA\ line. We show that NLTE inversions provide realistic estimates of physical quantities from synthetic...
Source: http://arxiv.org/abs/1203.4577v1
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by J. W. Maluf; F. F. Faria
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In this work a tetrad theory of gravity, invariant under conformal transformations, is investigated. The action of the theory is similar to the action of Maxwell's electromagnetism. The role of the electromagnetic gauge potential is played by the trace of the torsion tensor of the Weitzenb\"ock spacetime. It is shown that all static, spherically symmetric space-times, are solutions of the vacuum field equations. However, by fixing the gauge in the linearized form of the vacuum field...
Source: http://arxiv.org/abs/1203.0040v2
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by G. Venanzoni
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We review the latest experimental achievements on the hadronic cross section measurements at low energy which are of fundamental importance for a precise evaluation of the hadronic contribution to the g-2 of the muon. We also discuss the new proposed muon g-2 experiments, with particular emphasis on E989 at Fermilab which plans to improve the experimental uncertainty by a factor of 4 with respect to the previous E821 experiment at BNL
Source: http://arxiv.org/abs/1203.1501v1
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by L. D. Anderson; A. Zavagno; L. Deharveng; A. Abergel; F. Motte; Ph. Andre; J. -P. Bernard; S. Bontemps; M. Hennemann; T. Hill; J. A. Rodon; H. Roussel; D. Russeil
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Because of their relatively simple morphology, "bubble" HII regions have been instrumental to our understanding of star formation triggered by HII regions. With the far-infrared (FIR) spectral coverage of the Herschel satellite, we can access the wavelengths where these regions emit the majority of their energy through their dust emission. At Herschel wavelengths 70 micron to 500 micron, the emission associated with HII regions is dominated by the cool dust in their photodissociation...
Source: http://arxiv.org/abs/1203.5721v1
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by Riku Klén; Ville Suomala
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We consider metrics on Euclidean domains $\Omega\subset\R^n$ that are induced by continuous densities $\rho\colon\Omega\rightarrow(0,\infty)$ and study the Hausdorff and packing dimensions of the boundary of $\Omega$ with respect to these metrics.
Source: http://arxiv.org/abs/1005.1808v3
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We solve the inverse problem from the spectral measure and the inverse three-spectra problem for the class of singular Krein strings on a finite interval with trace class resolvents. The solutions of these problems are obtained by approximation with Stieltjes strings.
Source: http://arxiv.org/abs/1203.2271v1
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by W-Y. Pauchy Hwang
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We attempt to answer whether dark-matter galaxies could be formed in a time span of about $1\, Gyr$ or the age of the young Universe. If the dark-matter galaxies would exist in a time span of about 1 Gyr, then they might even dictate the formation of the ordinary-matter galaxies. The implications for the structure of our Universe would be tremendous. Thus, the search for dark-matter galaxies should be under way if possible.
Source: http://arxiv.org/abs/1203.1407v1
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by J. D. Watson; S. Mondal; G. Gardner; G. A. Csáthy; M. J. Manfra
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We report on the growth and electrical characterization of a series of two-dimensional hole systems (2DHSs) used to study the density dependence of low temperature mobility in 20 nm GaAs/AlGaAs quantum wells. The hole density was controlled by changing the Al mole fraction and the setback of the delta-doping layer. We varied the density over a range from 1.8 $\times$ 10$^{10}$ cm$^{-2}$ to 1.9 $\times$ 10$^{11}$ cm$^{-2}$ finding a nonmonotonic dependence of mobility on density at T = 0.3 K....
Source: http://arxiv.org/abs/1203.4312v1
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Learning how proteins fold will hardly have any impact in the way conventional -- active site centered -- drugs are designed. On the other hand, this knowledge is proving instrumental in defining a new paradigm for the identification of drugs against any target protein: folding inhibition. Targeting folding renders drugs less prone to elicit spontaneous genetic mutations which in many cases, notably in connection with viruses like the Human Immunodeficiency Virus (HIV), can block therapeutic...
Source: http://arxiv.org/abs/1203.3315v1
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We show that the distribution of luminosities of Brightest Cluster Galaxies in an SDSS-based group catalog suggests that BCG luminosities are just the statistical extremes of the group galaxy luminosity function. This latter happens to be very well approximated by the all-galaxy luminosity function (restricted to Mr
Source: http://arxiv.org/abs/1107.3652v2
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We consider the zero dissipation limit of the full compressible Navier-Stokes equations with Riemann initial data in the case of superposition of two rarefaction waves and a contact discontinuity. It is proved that for any suitably small viscosity $\varepsilon$ and heat conductivity $\kappa$ satisfying the relation \eqref{viscosity}, there exists a unique global piecewise smooth solution to the compressible Navier-Stokes equations. Moreover, as the viscosity $\varepsilon$ tends to zero, the...
Source: http://arxiv.org/abs/1203.1230v1
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by E. Enochs; S. Estrada
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In this note we extend the main results of [E. Enochs and S. Estrada, Relative homological algebra in the category of quasi-coherent sheaves. Adv. in Math. 194(2005), 284-295] to the category of cartesian modules over a flat presheaf of rings and on an arbitrary small category. This provides with new applications of that paper to the categories of quasi-coherent sheaves on an Artin stack or on a Deligne-Mumford stack.
Source: http://arxiv.org/abs/1203.5724v1
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by Michael A. Hill
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We present an introduction to the equivariant slice filtration. After reviewing the definitions and basic properties, we determine the slice dimension of various families of naturally arising spectra. This leads to an analysis of pullbacks of slices defined on quotient groups, producing new collections of slices. Building on this, we determine the slice tower for the Eilenberg-Mac Lane spectrum associated to a Mackey functor for a cyclic $p$-group. We then relate the Postnikov tower to the...
Source: http://arxiv.org/abs/1107.3582v2
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by Rory Smith; Richard R. Lane; Blair C. Conn; Michael Fellhauer
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We model the formation of Auriga's Wheel - a recently discovered collisional ring galaxy. Auriga's Wheel has a number of interesting features including a bridge of stars linking the neighbouring elliptical to the ring galaxy, and evidence for components of expansion and rotation within the ring. Using N-body/SPH modelling, we study collisions between an elliptical galaxy and a late-type disk galaxy. A near direct collision, with a mildy inclined disk, is found to reasonably reproduce the...
Source: http://arxiv.org/abs/1203.2610v1
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by Nicoló Spagnolo; Chiara Vitelli; Vito Giovanni Lucivero; Vittorio Giovannetti; Lorenzo Maccone; Fabio Sciarrino
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The sensitivity in optical interferometry is strongly affected by losses during the signal propagation or at the detection stage. The optimal quantum states of the probing signals in the presence of loss were recently found. However, in many cases of practical interest, their associated accuracy is worse than the one obtainable without employing quantum resources (e.g. entanglement and squeezing) but neglecting the detector's loss. Here we detail an experiment that can reach the latter even in...
Source: http://arxiv.org/abs/1107.3726v2
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by Raffaella Schneider; Kazuyuki Omukai; Marco Limongi; Andrea Ferrara; Ruben Salvaterra; Alessandro Chieffi; Simone Bianchi
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The relative importance of metals and dust grains in the formation of the first low-mass stars has been a subject of debate. The recently discovered Galactic halo star SDSS J102915+172927 (Caffau et al. 2011) has a mass less than 0.8 Msun and a metallicity of Z = 4.5 10^{-5} Zsun. We investigate the origin and properties of this star by reconstructing the physical conditions in its birth cloud. We show that the observed elemental abundance trend of SDSS J102915+172927 can be well fitted by the...
Source: http://arxiv.org/abs/1203.4234v1
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We investigate the Bose-Einstein Condensation on non homogeneous non amenable networks for the model describing arrays of Josephson junctions on perturbed Cayley Trees. The resulting topological model has also a mathematical interest in itself. The present paper is then the application to the Bose-Einstein Condensation phenomena, of the harmonic analysis aspects arising from additive and density zero perturbations, previously investigated by the author in a separate work. Concerning the...
Source: http://arxiv.org/abs/1203.5522v2
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We show that for every mixing orthogonal representation $\pi : \Z \to \mathcal O(H_\R)$, the abelian subalgebra $\LL(\Z)$ is maximal amenable in the crossed product ${\rm II}_1$ factor $\Gamma(H_\R)\dpr \rtimes_\pi \Z$ associated with the free Bogoljubov action of the representation $\pi$. This provides uncountably many non-isomorphic $A$-$A$-bimodules which are disjoint from the coarse $A$-$A$-bimodule and of the form $\LL^2(M \ominus A)$ where $A \subset M$ is a maximal amenable masa in a...
Source: http://arxiv.org/abs/1203.6743v1
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by Mrinal Kanti Roychowdhury
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The cookie-cutter-like set is defined as the limit set of a sequence of classical cookie-cutter mappings. For this cookie-cutter-like set first we have determined the topological pressure function, and then by Banach limit we have determined a unique Borel probability measure $\mu_h$ with the support the cookie-cutter-like set $E$. With the topological pressure and the measure $\mu_h$, we have shown that the fractal dimensions such as the Hausdorff dimension, the packing dimension and the...
Source: http://arxiv.org/abs/1203.2724v3
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by J. Takata; A. T. Okazaki; S. Nagataki; T. Naito; A. Kawachi; S. -H. Lee; M. Mori; K. Hayasaki; M. S. Yamaguchi; S. P. Owocki
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Temporal changes of X-ray to very-high-energy gamma-ray emissions from the pulsar-Be star binary PSR B1259-63/LS 2883 are studied based on 3-D SPH simulations of pulsar wind interaction with Be-disk and wind. We focus on the periastron passage of the binary and calculate the variation of the synchrotron and inverse-Compton emissions using the simulated shock geometry and pressure distribution of the pulsar wind. The characteristic double-peaked X-ray light curve from observations is reproduced...
Source: http://arxiv.org/abs/1203.2179v2
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by Isamu Iwanari
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In this paper we continue our development of tannakizations of symmetric monoidal infinity-categories, begun in our previous paper. The issue treated in this paper is the calculation of tannakizations of examples of symmetric monoidal stable infinity-categories with fiber functors. We consider the case of symmetric monoidal infinity-categories of perfect complexes on perfect derived stacks. The first main result especially says that our tannakization includes the bar construction for an...
Source: http://arxiv.org/abs/1203.0492v2
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by Johan Helsing; Karl-Mikael Perfekt
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An efficient integral equation based solver is constructed for the electrostatic problem on domains with cuboidal inclusions. It can be used to compute the polarizability of a dielectric cube in a dielectric background medium at virtually every permittivity ratio for which it exists. For example, polarizabilities accurate to between five and ten digits are obtained (as complex limits) for negative permittivity ratios in minutes on a standard workstation. In passing, the capacitance of the unit...
Source: http://arxiv.org/abs/1203.5997v3
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Let F be a finite field and let C be a smooth projective curve over F. For some smooth projective surfaces X over F we establish that the third unramified cohomology of the product of X and C vanishes. This applies in particular to geometrically rational surfaces. Soit F un corps fini et soit C une courbe projective et lisse sur F. Pour certaines surfaces projectives et lisses X sur F on \'etablit la nullit\'e du troisi\`eme groupe de cohomologie non ramifi\'ee du produit de X et C. Cela...
Source: http://arxiv.org/abs/1203.2141v1
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by Rajeev K. Shakya; Yatindra Nath Singh; Nishchal K. Verma
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We study the problem of medium access control in domain of event-driven wireless sensor networks (WSNs). In this kind of WSN, sensor nodes send data to sink node only when an event occurs in the monitoring area. The nodes in this kind of WSNs encounter correlated traffic as a subset of nodes start sending data by sensing a common event simultaneously. We wish to rethink of medium access control (MAC) for this type of traffic characteristics. For WSNs, many existing MAC protocols utilize the...
Source: http://arxiv.org/abs/1203.5874v2
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The game of chess as always been viewed as an iconic representation of intellectual prowess. Since the very beginning of computer science, the challenge of being able to program a computer capable of playing chess and beating humans has been alive and used both as a mark to measure hardware/software progresses and as an ongoing programming challenge leading to numerous discoveries. In the early days of computer science it was a topic for specialists. But as computers were democratized, and the...
Source: http://arxiv.org/abs/1203.3434v1
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by M. Simon; Joshua E. Schlieder; Ana-Maria Constantin; Michele Silverstein
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The Nearby Young Moving Groups (NYMGs) of stars are ideal for the study of evolution circumstellar disks in which planets may form because their ages range from a few Myr to about 100 Myr, about the same as the interval over which planets are thought to form. Their stars are distributed over large regions of the sky. Hence, the Wide Field Infrared Survey Explorer (WISE) which scanned the entire sky in four bands from 3.4 to 22.1 mu provides a database well-suited for the study of members of the...
Source: http://arxiv.org/abs/1203.3202v1
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by Osama Attia; Tamer ElBatt
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In this paper, we analyze the performance of cooperative content caching in vehicular ad hoc networks (VANETs). In particular, we characterize, using analysis and simulations, the behavior of the probability of outage (i.e. not finding a requested data chunk at a neighbor) under freeway vehicular mobility. First, we introduce a formal definition for the probability of outage in the context of cooperative content caching. Second, we characterize, analytically, the outage probability under...
Source: http://arxiv.org/abs/1203.0657v1