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The Ginzburg - Landau theory is used for the superconducting structures free energy fluctuations study. On its basis, we have defined the value of the heat capacity jump in the macroscopic zero-dimensional sample and in the zero-dimensional microstructures ensemble of the total volume equal to the macroscopic sample volume. The inference is made that in the Ginzburg - Landau methodology frameworks, it is essential to take into account the superconducting clean sample effective dimensionality only on the last stage of its thermodynamical characteristics calculation.
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arxiv:0910.4641
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Let $K$ be a field and $S=K[x_1,...,x_n]$. In 1982, Stanley defined what is now called the Stanley depth of an $S$-module $M$, denoted $\sdepth(M)$, and conjectured that $\depth(M) \le \sdepth(M)$ for all finitely generated $S$-modules $M$. This conjecture remains open for most cases. However, Herzog, Vladoiu and Zheng recently proposed a method of attack in the case when $M = I / J$ with $J \subset I$ being monomial $S$-ideals. Specifically, their method associates $M$ with a partially ordered set. In this paper we take advantage of this association by using combinatorial tools to analyze squarefree Veronese ideals in $S$. In particular, if $I_{n,d}$ is the squarefree Veronese ideal generated by all squarefree monomials of degree $d$, we show that if $1\le d\le n < 5d+4$, then $\sdepth(I_{n,d})= \floor{\binom{n}{d+1}\Big/\binom{n}{d}}+d$, and if $d\geq 1$ and $n\ge 5d+4$, then $d+3\le \sdepth(I_{n,d}) \le \floor{\binom{n}{d+1}\Big/\binom{n}{d}}+d$.
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arxiv:0910.4645
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The presence of tau leptons in the final state is an important signature in searches for physics beyond the Standard Model. Hadronically decaying tau leptons can be reconstructed over a wide kinematic range at ATLAS. The reconstruction algorithm for hadronically decaying tau leptons and the performance of tau lepton identification is described. A review of physics processes with tau lepton final states is given, ranging from Standard Model processes in early data, such as W and Z boson production, to searches for new phenomena beyond the Standard Model.
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arxiv:0910.4727
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The authors found necessary and sufficient conditions for Samuelson's web to be of maximum rank.
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arxiv:0910.4749
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We report a first measurement of inclusive B -> X_s eta decays, where X_s is a charmless state with unit strangeness. The measurement is based on a pseudo-inclusive reconstruction technique and uses a sample of 657 x 10^6 BB-bar pairs accumulated with the Belle detector at the KEKB e^+e^- collider. For M_{X_s} < 2.6 GeV/c^2, we measure a branching fraction of (26.1 +/- 3.0 (stat) +1.9 -2.1 (syst) +4.0 -7.1 (model)) x 10^-5 and a direct CP asymmetry of A_{CP} = -0.13 +/- 0.04 +0.02 -0.03. Over half of the signal occurs in the range M_{X_s} > 1.8 GeV/c^2.
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arxiv:0910.4751
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We consider the dynamics of finite-size disordered systems as defined by a master equation satisfying detailed balance. The master equation can be mapped onto a Schr\"odinger equation in configuration space, where the quantum Hamiltonian $H$ has the generic form of an Anderson localization tight-binding model. The largest relaxation time $t_{eq}$ governing the convergence towards Boltzmann equilibrium is determined by the lowest non-vanishing eigenvalue $E_1=1/t_{eq}$ of $H$ (the lowest eigenvalue being $E_0=0$). So the relaxation time $t_{eq}$ can be computed {\it without simulating the dynamics} by any eigenvalue method able to compute the first excited energy $E_1$. Here we use the 'conjugate gradient' method to determine $E_1$ in each disordered sample and present numerical results on the statistics of the relaxation time $t_{eq}$ over the disordered samples of a given size for two models : (i) for the random walk in a self-affine potential of Hurst exponent $H$ on a two-dimensional square of size $L \times L$, we find the activated scaling $\ln t_{eq}(L) \sim L^{\psi}$ with $\psi=H$ as expected; (ii) for the dynamics of the Sherrington-Kirkpatrick spin-glass model of $N$ spins, we find the growth $\ln t_{eq}(N) \sim N^{\psi}$ with $\psi=1/3$ in agreement with most previous Monte-Carlo measures. In addition, we find that the rescaled distribution of $(\ln t_{eq})$ decays as $e^{- u^{\eta}}$ for large $u$ with a tail exponent of order $\eta \simeq 1.36$. We give a rare-event interpretation of this value, that points towards a sample-to-sample fluctuation exponent of order $\psi_{width} \simeq 0.26$ for the barrier.
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arxiv:0910.4833
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SuperAGILE is the hard X-ray monitor of the AGILE gamma ray mission, in orbit since 23$^{rd}$ April 2007. It is an imaging experiment based on a set of four independent silicon strip detectors, equipped with one-dimensional coded masks, operating in the nominal energy range 18-60 keV. The main goal of SuperAGILE is the observation of cosmic sources simultaneously with the main gamma-ray AGILE experiment, the Gamma Ray Imaging Detector (GRID). Given its $\sim$steradian-wide field of view and its $\sim$15 mCrab day-sensitivity, SuperAGILE is also well suited for the long-term monitoring of Galactic compact objects and the detection of bright transients. The SuperAGILE detector properties and design allow for a 6 arcmin angular resolution in each of the two independent orthogonal projections of the celestial coordinates. Photon by photon data are continuously available by the experiment telemetry, and are used to derive images and fluxes of individual sources, with integration times depending on the source intensity and position in the field of view. In this paper we report on the main scientific results achieved by SuperAGILE over its first two years in orbit, until April 2009.
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arxiv:0910.4895
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We classify static manifolds which admit more than one static decomposition whenever a condition on the curvature is fullfilled. For this, we take a standard static vector field and analyze its associated one parameter family of projections onto the base. We show that the base itself is a static manifold and the warping function satisfies severe restrictions, leading us to our classification results. Moreover, we show that certain condition on the lightlike sectional curvature ensures the uniqueness of static decomposition for Lorentzian manifolds.
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arxiv:0910.4933
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The symmetry properties of the Cooper pairing problem for multi-component ultra-cold dipolar molecular systems are investigated. The dipolar anisotropy provides a natural and robust mechanism for both triplet and singlet Cooper pairing to first order in the interaction strength. With a purely dipolar interaction, the triplet $p_z$-like polar pairing is the most dominant. A short-range attractive interaction can enhance the singlet pairing to be nearly degenerate with the triplet pairing. We point out that these two pairing channels can mix by developing a relative phase of $\pm\frac{\pi}{2}$, thus spontaneously breaking time-reversal symmetry. We also suggest the possibility of such mixing of triplet and singlet pairing in other systems.
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arxiv:0910.4940
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We present a catalogue of 17 filamentary X-ray features located within a 68\times34 arcmin^2 view centred on the Galactic Centre region from images taken by Chandra. These features are described by their morphological and spectral properties. Many of the X-ray features have non-thermal spectra that are well fitted by an absorbed power law. Of the 17 features, we find six that have not been previously detected, four of which are outside the immediate 20\times20 arcmin^2 area centred on the Galactic Centre. Seven of the 17 identified filaments have morphological and spectral properties expected for pulsar wind nebulae (PWNe) with X-ray luminosities of 5\times10^32 to 10^34 erg s^-1 in the 2.0-10.0 keV band and photon indices in the range of \Gamma = 1.1 to 1.9. In one feature, we suggest the strong neutral Fe K\alpha emission line to be a possible indicator for past activity of Sgr A*. For G359.942-0.03, a particular filament of interest, we propose the model of a ram pressure confined stellar wind bubble from a massive star to account for the morphology, spectral shape and 6.7 keV He-like Fe emission detected. We also present a piecewise spectral analysis on two features of interest, G0.13-0.11 and G359.89-0.08, to further examine their physical interpretations. This analysis favours the PWN scenario for these features.
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arxiv:0910.4944
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Electroweak interactions need three Nambu-Goldstone bosons to provide a mass to the W and the Z gauge bosons but they also need an ultra-violet moderator or new physics to unitarize the gauge boson scattering amplitudes. In this talk, I will present various recent models of physics at the Fermi scale: several deformations of the Minimal Supersymmetric Standard Model, Little Higgs models, holographic composite Higgs models, 5D Higgsless models.
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arxiv:0910.4976
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We present axisymmetric hydrodynamical simulations of the long-term accretion of a rotating GRB progenitor star, a "collapsar," onto the central compact object. The simulations were carried out with the adaptive mesh refinement code FLASH in two spatial dimensions and with an explicit shear viscosity. The evolution of the central accretion rate exhibits phases reminiscent of the long GRB gamma-ray and X-ray light curve, which lends support to the proposal that the luminosity is modulated by the central accretion rate. After a few tens of seconds, an accretion shock sweeps outward through the star. The formation and outward expansion of the accretion shock is accompanied with a sudden and rapid power-law decline in the central accretion rate Mdot ~ t^{-2.8}, which resembles the L_X ~ t^{-3} decline observed in the X-ray light curves. The collapsed, shock-heated stellar envelope settles into a thick, low-mass equatorial disk embedded within a massive, pressure-supported atmosphere. After a few hundred seconds, the inflow of low-angular-momentum material in the axial funnel reverses into an outflow from the surface of the thick disk. Meanwhile, the rapid decline of the accretion rate slows down, or even settles a in steady state with Mdot ~ 5x10^{-5} Msun/s, which resembles the "plateau" phase in the X-ray light curve. While the duration of the "prompt" phase depends on the resolution in our simulations, we provide an analytical model taking into account neutrino losses that estimates the duration to be ~20 s. The model suggests that the steep decline in GRB X-ray light curves is triggered by the circularization of the infalling stellar envelope at radii where the virial temperature is below ~10^{10} K, such that neutrino cooling shuts off and an outward expansion of the accretion shock becomes imminent.
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arxiv:0910.4989
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In a recent work, Dancs and He found an Euler-type formula for $\,\zeta{(2\,n+1)}$, $\,n\,$ being a positive integer, which contains a series they could not reduce to a finite closed-form. This open problem reveals a greater complexity in comparison to $\zeta(2n)$, which is a rational multiple of $\pi^{2n}$. For the Dirichlet beta function, the things are `inverse': $\beta(2n+1)$ is a rational multiple of $\pi^{2n+1}$ and no closed-form expression is known for $\beta(2n)$. Here in this work, I modify the Dancs-He approach in order to derive an Euler-type formula for $\,\beta{(2n)}$, including $\,\beta{(2)} = G$, the Catalan's constant. I also convert the resulting series into zeta series, which yields new exact closed-form expressions for a class of zeta series involving $\,\beta{(2n)}$ and a finite number of odd zeta values. A closed-form expression for a certain zeta series is also conjectured.
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arxiv:0910.5004
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Let X be a projective surface, let \sigma be an automorphism of X, and let L be a \sigma-ample invertible sheaf on X. We study the properties of a family of subrings, parameterized by geometric data, of the twisted homogeneous coordinate ring B(X, L, \sigma). In particular, we find necessary and sufficient conditions for these subrings to be noetherian. We also study their homological properties, their associated noncommutative projective schemes, and when they are maximal orders. In the process, we produce new examples of maximal orders; these are graded and have the property that no Veronese subring is generated in degree 1. Our results are used in a companion paper to give defining data for a large class of noncommutative projective surfaces.
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arxiv:0910.5016
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The stationary isotropic Poisson line process was used to derive upper bounds on mean excess network geodesic length in Aldous and Kendall [Adv. in Appl. Probab. 40 (2008) 1-21]. The current paper presents a study of the geometry and fluctuations of near-geodesics in the network generated by the line process. The notion of a "Poissonian city" is introduced, in which connections between pairs of nodes are made using simple "no-overshoot" paths based on the Poisson line process. Asymptotics for geometric features and random variation in length are computed for such near-geodesic paths; it is shown that they traverse the network with an order of efficiency comparable to that of true network geodesics. Mean characteristics and limiting behavior at the center are computed for a natural network flow. Comparisons are drawn with similar network flows in a city based on a comparable rectilinear grid. A concluding section discusses several open problems.
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arxiv:0910.5115
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It is shown that the Foldy-Wouthuysen transformation for relativistic particles in strong external fields provides the possibility of obtaining a meaningful classical limit of the relativistic quantum mechanics. The full agreement between quantum and classical theories is proved. The coincidence of the semiclassical equations of motion of particles and their spins with the corresponding classical equations is established. The Niels Bohr's correspondence principle is valid not only in the limit of large spin quantum numbers but also for particles with any spin as well as for spinless particles.
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arxiv:0910.5155
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Diffractive physics program for ATLAS and CMS is discussed with emphasis on measurements of central exclusive processes. At low luminosities, a L1 trigger based on requiring rapidity gaps can be used, while at high luminosities, the use of proton taggers proposed to be placed at 220 m and 420 m from the interaction point is foreseen.
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arxiv:0910.5205
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The classical two-capacitor problem shows a mysterious lose of energy even under lossless conditions and questions the basic understanding of energy relation in a capacitor. Here, we present a solution to the classical two-capacitor problem. We find that by reinterpreting the energy calculations we achieve no lose of energy thereby obeying the conservation of energy law.
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arxiv:0910.5279
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We construct vertex operators for massless higher spin fields in RNS superstring theory and compute some of their three-point correlators, describing gauge-invariant cubic interactions of the massless higher spins. The Fierz-Pauli on-shell conditions for the higher spins (including tracelessness and vanishing divergence) follow from the BRST-invariance conditions for the vertex operators constructed in this paper. The gauge symmetries of the massless higher spins emerge as a result of the BRST nontriviality conditions for these operators, being equivalent to transformations with the traceless gauge parameter in the Fronsdal's approach. The gauge invariance of the interaction terms of the higher spins is therefore ensured automatically by that of the vertex operators in string theory. We develop general algorithm to compute the cubic interactions of the massless higher spins and use it to explicitly describe the gauge-invariant interaction of two $s=3$ and one $s=4$ massless particles.
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arxiv:0910.5338
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We consider spin Hall effect in a system of massless Dirac fermions in a graphene lattice. Two types of spin-orbit interaction, pertinent to the graphene lattice, are taken into account - the intrinsic and Rashba terms. Assuming perfect crystal lattice, we calculate the topological contribution to spin Hall conductivity. When both interactions are present, their interplay is shown to lead to some peculiarities in the dependence of spin Hall conductivity on the Fermi level.
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arxiv:0910.5352
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The magnetic properties of graphene on finite geometries are studied using a self-consistent mean-field theory of the Hubbard model. This approach is known to predict ferromagnetic edge states close to the zig-zag edges in single-layer graphene quantum dots and nanoribbons. In order to assess the accuracy of this method, we perform complementary exact diagonalization and quantum Monte Carlo simulations. We observe good quantitative agreement for all quantities investigated provided that the Coulomb interaction is not too strong.
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arxiv:0910.5360
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We study the $SIG$ dimension of trees under $L_{\infty}$ metric and answer an open problem posed by Michael and Quint (Discrete Applied Mathematics: 127, pages 447-460, 2003). Let $T$ be a tree with atleast two vertices. For each $v\in V(T)$, let leaf-degree$(v)$ denote the number of neighbours of $v$ that are leaves. We define the maximum leaf-degree as $\alpha(T) = \max_{x \in V(T)}$ leaf-degree$(x)$. Let $S = \{v\in V(T) |$ leaf-degree$(v) = \alpha\}$. If $|S| = 1$, we define $\beta(T) = \alpha(T) - 1$. Otherwise define $\beta(T) = \alpha(T)$. We show that for a tree $T$, $SIG_\infty(T) = \lceil \log_2(\beta + 2)\rceil$ where $\beta = \beta (T)$, provided $\beta$ is not of the form $2^k - 1$, for some positive integer $k \geq 1$. If $\beta = 2^k - 1$, then $SIG_\infty (T) \in \{k, k+1\}$. We show that both values are possible.
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arxiv:0910.5380
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We investigate entanglement transfer from a system of two spin-entangled electron-hole pairs, each placed in a separate single mode cavity, to the photons emitted during their recombination process. Dipole selection rules and a splitting between the light-hole and the heavy-hole subbands are the crucial ingredients establishing a one-to-one correspondence between electron spins and circular photon polarizations. To account for the measurement of the photons as well as dephasing effects, we choose a stochastic Schroedinger equation and a conditional master equation approach, respectively. The influence of interactions with the environment as well as asymmetries in the coherent couplings on the photon-entanglement is analyzed for two concrete measurement schemes. The first one is designed to violate the Clauser-Horne-Shimony-Holt (CHSH) inequality, while the second one employs the visibility of interference fringes to prove the entanglement of the photons. Because of the spatial separation of the entangled electronic system over two quantum dots, a successful verification of entangled photons emitted by this system would imply the detection of nonlocal spin-entanglement of massive particles in a solid state structure.
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arxiv:0910.5382
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We prove the existence and uniqueness of a strong solution of a stochastic differential equation with normal reflection representing the random motion of finitely many globules. Each globule is a sphere with time-dependent random radius and a center moving according to a diffusion process. The spheres are hard, hence non-intersecting, which induces in the equation a reflection term with a local (collision-)time. A smooth interaction is considered too and, in the particular case of a gradient system, the reversible measure of the dynamics is given. In the proofs, we analyze geometrical properties of the boundary of the set in which the process takes its values, in particular the so-called Uniform Exterior Sphere and Uniform Normal Cone properties. These techniques extend to other hard core models of objects with a time-dependent random characteristic: we present here an application to the random motion of a chain-like molecule.
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arxiv:0910.5394
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We theoretically study the polarization entanglement of photons generated by the biexciton cascade in a GaAs/InAs semiconductor quantum dot (QD), located in a nano cavity. A detailed analysis of the complex interplay between photon- and carrier coherences and phonons which occurs during the cascade allows us to clearly identify where the entanglement is generated and destroyed. A quantum state tomography is performed for varying exciton fine structure splittings. By constructing an effective multi-phonon Hamiltonian which couples the continuum of the wetting layer states to the QD we investigate the relaxation of the biexciton and exciton states. This consistently introduces a temperature dependence to the cascade. Considering typical Stranski-Karastanov grown QDs, for temperatures around 80 K the degree of entanglement starts to be affected by the dephasing of the exciton states and is ultimately lost above 120 K.
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arxiv:0910.5445
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Conditional independence in a multivariate normal (or Gaussian) distribution is characterized by the vanishing of subdeterminants of the distribution's covariance matrix. Gaussian conditional independence models thus correspond to algebraic subsets of the cone of positive definite matrices. For statistical inference in such models it is important to know whether or not the model contains singularities. We study this issue in models involving up to four random variables. In particular, we give examples of conditional independence relations which, despite being probabilistically representable, yield models that non-trivially decompose into a finite union of several smooth submodels.
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arxiv:0910.5447
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We propose and apply the finite-element discrete variable representation to express the nonequilibrium Green's function for strongly inhomogeneous quantum systems. This method is highly favorable against a general basis approach with regard to numerical complexity, memory resources, and computation time. Its flexibility also allows for an accurate representation of spatially extended hamiltonians, and thus opens the way towards a direct solution of the two-time Schwinger/Keldysh/Kadanoff-Baym equations on spatial grids, including e.g. the description of highly excited states in atoms. As first benchmarks, we compute and characterize, in Hartree-Fock and second Born approximation, the ground states of the He atom, the H$_2$ molecule and the LiH molecule in one spatial dimension. Thereby, the ground-state/binding energies, densities and bond-lengths are compared with the direct solution of the time-dependent Schr\"odinger equation.
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arxiv:0910.5458
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Recent analyses suggest that in TeV scales that will be made accessible at the LHC copious amounts of color scalar parton bound states may be produced. Would this be the case, the scalars would leave long enough to interact and this could lead to new physics. These interaction could be direct, but also take place with a mediation of the dense parton medium through which they propagate. Since multiple processes would have to be included, the latter case is too convoluted to be treated with perturbative methods applied to the Standard Model. We explore a possibility of describing such interaction by a nonlocal Lagrangian which is an infinite polynomial in the field variables, momentum and mass. We treat all scalars as identical, use a O(N)-symmetric Lagrangian, where N is the number of scalars and discuss the problem in 1/N expansion. Nonrenormalizable by all traditional criteria, such model still requires only a limited set of multiplicative renormalizations, provided that the parameters in the Lagrangian are not treated as an infinite set of independent coupling constants, but as finite expansion coefficients of the Lagrangian in powers of field variables, mass and momenta. The necessary constraints on the relative magnitudes of these coefficients can be determined order by order in a double series in the single coupling constant and 1/N.
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arxiv:0910.5506
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Recent discoveries, as well as open questions, in experimentally realized correlated electron materials are reviewed. In particular, high temperature superconductivity in the cuprates and in the recently discovered iron pnictides, possible chiral p-wave superconductivity in strontium ruthenate, the search for quantum spin liquid behavior in real materials, and new experimental discoveries in topological insulators are discussed.
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arxiv:0910.5513
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Gene regulatory circuits show significant stochastic fluctuations in their circuit signals due to the low copy number of transcription factors. When a gene circuit component is connected to an existing circuit, the dynamic properties of the existing circuit can be affected by the connected component. In this paper, we investigate modularity in the dynamics of the gene circuit based on stochastic fluctuations in the circuit signals. We show that the noise in the output signal of the existing circuit can be affected significantly when the output is connected to the input of another circuit component. More specifically, the output signal noise can show significantly longer correlations when the two components are connected. This equivalently means that the noise power spectral density becomes narrower. We define the relative change in the correlation time or the spectrum bandwidth by stochastic retroactivity, which is shown to be directly related to the retroactivity defined in the deterministic framework by del Vecchio et al. This provides an insight on how to measure retroactivity, by investigating stochastic fluctuations in gene expression levels, more specifically, by obtaining an autocorrelation function of the fluctuations. We also provide an interesting aspect of the frequency response of the circuit. We show that depending on the magnitude of operating frequencies, different kinds of signals need to be preferably chosen for circuit description in a modular fashion: at low enough frequency, expression level of transcription factor that are not bound to their specific promoter region needs to be chosen, and at high enough frequency, that of the total transcription factor, both bound and unbound, does.
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arxiv:0910.5522
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The construction (by Kapranov) of the space of infinitesimal paths on a manifold is extended to include higher dimensional infinitesimal objects, encoding contractions of infinitesimal loops. This full infinitesimal groupoid is shown to have the algebra of polyvector fields as its non-linear cohomology.
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arxiv:0910.5525
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A detailed chemical composition analysis based on a high-resolution (R=35,000) CCD spectrum is presented for a newly discovered post-AGB star in the globular cluster M79 for the first time. The elemental abundance results of M79 Post-AGB star are found to be [C/Fe]=-0.7, [O/Fe]=+1.4, [alpha- process/Fe]=0.5, and [s-process/Fe]=-0.1. The surprising result is that the iron abundance of the star is apparently about 0.6 dex less than that of the cluster's red giants as reported by published studies including a recent high-resolution spectroscopic analysis by Carretta and colleagues.
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arxiv:0910.5567
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We report the analysis of a binary blue straggler in NGC 6752 with a short orbital period of 0.315 d and a W UMA-type light curve. We use photometric data spanning 13 years to place limits on the mass ratio (0.15<q<0.35), luminosity ratio (L1/L2 about 4.0) and the ratio of the radii of the components (r1/r2 about 2.0). The effective temperatures of the components are nearly identical, and the system is detached or semi-detached (in the latter case the component filling its Roche lobe is the secondary). Such a configuration is unusual given the shortness of the orbital period, and it must have resulted from substantial mass exchange. We suggest that some secondaries of W UMa-type stars, normally regarded as main sequence objects which fill their Roche lobes to different degrees, in fact may be shell-burning cores of originally more massive components.
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arxiv:0910.5609
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We deal here with the geometry of the twistor fibration $\mathcal{Z} \to \bb{S}^3_1$ over the De Sitter 3-space. The total space $\mathcal{Z}$ is a five dimensional reductive homogeneous space with two canonical invariant almost CR structures. Fixed the normal metric on $\mathcal{Z}$ we study the harmonic map equation for smooth maps of Riemann surfaces into $\mathcal{Z}$. A characterization of spacelike surfaces with harmonic twistor lifts to $\mathcal{Z}$ is obtained. It is also shown that the harmonic map equation for twistor lifts can be formulated as the curvature vanishing of an $\bb{S}^1$-loop of connections i.e. harmonic twistor lifts exist within $\bb{S}^1$-families. Special harmonic maps such as holomorphic twistor lifts are also considered and some remarks concerning (compact) vacua of the twistor energy are given.
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arxiv:0910.5626
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In this paper we introduce the elementary notion of Pl\"ucker form of a pair $(E,S)$, where $E$ is a vector bundle of rank $r$ on a smooth, irreducible, complex projective variety $X$ and $S \subset H^0(E)$ is a subspace of dimension $rm$. We apply this notion to the study of theta map $\theta_r$ on the moduli space $SU_X(r,0)$ of semistable vector bundles of rank $r$ and trivial determinant on a curve $X$ of genus $g$. We prove that $\theta_r$ is generically injective if $X$ is general and $g >> r$.
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arxiv:0910.5630
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We have studied the correlation effects in Cs and Fr arising from the interplay of the residual Coulomb interaction to all orders and the neutral weak interaction which gives rise to the parity violating electric dipole transition to first order, within the framework of the relativistic coupled-cluster theory which circumvents the constrain of explicitly summing over the intermediate states. We observe that, the contributions arising from the perturbed doubly excited states are quite significant and hence, any calculation should not be considered accurate unless it includes the perturbed double excitations comprehensively. In this article, we have reported a comparative study of various results related to the parity violation in Cs and Fr.
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arxiv:0910.5661
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A new entanglement measure, which is called D-concurrence, is proposed. Then the upper and lower bounds for D-concurrence are obtained and the relationship between D-concurrence and the usual concurrence of Wootters was established. In addition, comparing with the usual concurrence, D-concurrence has some special merits.
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arxiv:0910.5769
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We analyze the dynamics of the entanglement in two independent non-Markovian channels. In particular, we focus on the entanglement dynamics as a function of the initial states and the channel parameters like the temperature and the ratio $r$ between $\omega_0$ the characteristic frequency of the quantum system of interest, and $\omega_c$ the cut-off frequency of Ohmic reservoir. We give a stationary analysis of the concurrence and find that the dynamic of non-markovian entanglement concurrence $\mathcal{C}_{\rho}(t)$ at temperature $k_BT=0$ is different from the $k_BT>0$ case. We find that "entanglement sudden death" (ESD) depends on the initial state when $k_BT=0$, otherwise the concurrence always disappear at finite time when $k_BT>0$, which means that ESD must happen. The main result of this paper is that the non-Markovian entanglement dynamic is fundamentally different from the Markovian one. In the Markovian channel, entanglement decays exponentially and vanishes only asymptotically, but in the non-Markovian channel the concurrence $\mathcal{C}_{\rho}(t)$ oscillates, especially in the high temperature case. Then an open-loop controller adjusted by the temperature is proposed to control the entanglement and prolong the ESD time.
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arxiv:0910.5793
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We demonstrate in theory that it is possible to all-electrically manipulate the RKKY interaction in a quasi-one-dimensional electron gas embedded in a semiconductor heterostructure, in the presence of Rashba and Dresselhaus spin-orbit interaction. In an undoped semiconductor quantum wire where intermediate excitations are gapped, the interaction becomes the short-ranged Bloembergen-Rowland super-exchange interaction. Owing to the interplay of different types of spin-orbit interaction, the interaction can be controlled to realize various spin models, e.g., isotropic and anisotropic Heisenberg-like models, Ising-like models with additional Dzyaloshinsky-Moriya terms, by tuning the external electric field and designing the crystallographic directions. Such controllable interaction forms a basis for quantum computing with localized spins and quantum matters in spin lattices.
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arxiv:0910.5800
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The detection of rotational transitions of the AlO radical at millimeter wavelengths from an astronomical source has recently been reported. In view of this, rotational transitions in the ground X^2 Sigma^+ state of AlO have been reinvestigated. Comparisons between Fourier transform and microwave data indicate a discrepancy regarding the derived value of gamma_D in the v = 0 level of the ground state. This discrepancy is discussed in the light of comparisons between experimental data and synthesized rotational spectra in the v = 0, 1 and 2 levels of X^2 Sigma^+. A list of calculated rotational lines in v = 0, 1 and 2 of the ground state up to N' = 11 is presented which should aid astronomers in analysis and interpretation of observed AlO data and also facilitate future searches for this radical.
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arxiv:0910.5813
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We have used the zCOSMOS-bright 10k sample to identify 3244 Spitzer/MIPS 24-micron-selected galaxies with 0.06< S(24um)< 0.50 mJy and I(AB)<22.5, over 1.5 deg^2 of the COSMOS field, and studied different spectral properties, depending on redshift. At 0.2<z<0.3, we found that different reddening laws of common use in the literature explain the dust extinction properties of around 80% of our infrared (IR) sources, within the error bars. For up to 16% of objects, instead, the Halpha/Hbeta ratios are too high for their IR/UV attenuations, which is probably a consequence of inhomogenous dust distributions. In only a few of our galaxies at 0.2<z<0.3 the IR emission could be mainly produced by dust heated by old rather than young stars. Besides, the line ratios of ~22% of our galaxies suggest that they might be star-formation/nuclear-activity composite systems. At 0.5<z<0.7, we estimated galaxy metallicities for 301 galaxies: at least 12% of them are securely below the upper-branch mass-metallicity trend, which is consistent with the local relation. Finally, we performed a combined analysis of the Hdelta equivalent-width versus Dn(4000) diagram for 1722 faint and bright 24um galaxies at 0.6<z<1.0, spanning two decades in mid-IR luminosity. We found that, while secondary bursts of star formation are necessary to explain the position of the most luminous IR galaxies in that diagram, quiescent, exponentially-declining star formation histories can well reproduce the spectral properties of ~40% of the less luminous sources. Our results suggest a transition in the possible modes of star formation at total IR luminosities L(TIR)=(3 +/-2)x10^11 Lsun.
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arxiv:0910.5824
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Let F1 and F2 be independent copies of correlated fractal percolation, with Hausdorff dimensions dimH(F1) and dimH(F2). Consider the following question: does dimH(F1)+dimH(F2)>1 imply that their algebraic difference F1-F2 will contain an interval? The well known Palis conjecture states that `generically' this should be true. Recent work by Kuijvenhoven and the first author (arXiv:0811.0525) on random Cantor sets can not answer this question as their condition on the joint survival distributions of the generating process is not satisfied by correlated fractal percolation. We develop a new condition which permits us to solve the problem, and we prove that the condition of (arXiv:0811.0525) implies our condition. Independently of this we give a solution to the critical case, yielding that a strong version of the Palis conjecture holds for fractal percolation and correlated fractal percolation: the algebraic difference contains an interval almost surely if and only if the sum of the Hausdorff dimensions of the random Cantor sets exceeds one.
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arxiv:0910.5865
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For the electromagnetic interaction of two particles the relativistic quantum mechanics equations are proposed. These equations are solved for the case when one particle has a small mass and moves freely. The initial wave functions are supposed to be concentrated at the coordinates origin. The energy spectrum of another particle wave function is defined by the initial wave function of the free moving particle. Choosing the initial wave function of the free moving particle it is possible to obtain a practically arbitrary energy spectrum.
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arxiv:0910.5939
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We present the full source catalogue from the Australia Telescope 20 GHz (AT20G) Survey. The AT20G is a blind radio survey carried out at 20 GHz with the Australia Telescope Compact Array (ATCA) from 2004 to 2008, and covers the whole sky south of declination 0 deg. The AT20G source catalogue presented here is an order of magnitude larger than any previous catalogue of high-frequency radio sources, and includes 5890 sources above a 20 GHz flux-density limit of 40 mJy. All AT20G sources have total intensity and polarisation measured at 20 GHz, and most sources south of declination -15 deg also have near-simultaneous flux-density measurements at 5 and 8 GHz. A total of 1559 sources were detected in polarised total intensity at one or more of the three frequencies. We detect a small but significant population of non-thermal sources that are either undetected or have only weak detections in low-frequency catalogues. We introduce the term Ultra-Inverted Spectrum (UIS) to describe these radio sources, which have a spectral index alpha(5, 20) > +0.7 and which constitute roughly 1.2 per cent of the AT20G sample. The 20 GHz flux densities measured for the strongest AT20G sources are in excellent agreement with the WMAP 5-year source catalogue of Wright et al. (2009), and we find that the WMAP source catalogue is close to complete for sources stronger than 1.5 Jy at 23 GHz.
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arxiv:0911.0002
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The order submission and cancelation processes are two crucial aspects in the price formation of stocks traded in order-driven markets. We investigate the dynamics of order cancelation by studying the statistical properties of inter-cancelation durations defined as the waiting times between consecutive order cancelations of 22 liquid stocks traded on the Shenzhen Stock Exchange of China in year 2003. Three types of cancelations are considered including cancelation of any limit orders, of buy limit orders and of sell limit orders. We find that the distributions of the inter-cancelation durations of individual stocks can be well modeled by Weibulls for each type of cancelation and the distributions of rescaled durations of each type of cancelations exhibit a scaling behavior for different stocks. Complex intraday patterns are also unveiled in the inter-cancelation durations. The detrended fluctuation analysis (DFA) and the multifractal DFA show that the inter-cancelation durations possess long-term memory and multifractal nature, which are not influenced by the intraday patterns. No clear crossover phenomenon is observed in the detrended fluctuation functions with respect to the time scale. These findings indicate that the cancelation of limit orders is a non-Poisson process, which has potential worth in the construction of order-driven market models.
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arxiv:0911.0057
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We prove that for any operator $T$ on $ \ell^\infty(H^1 (\bT))$, the identity factores through $T$ or $\Id - T$. We re-prove analogous results of H.M. Wark for the spaces $\ell^infty(H^p(\bT))$, $1<p <\infty$. In the present paper direct combinatorics of colored dyadic intervals replaces the dependence on Szemeredi's theorem in the work of H. M. Wark.
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arxiv:0911.0074
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We revisit the well-known problem of sorting under partial information: sort a finite set given the outcomes of comparisons between some pairs of elements. The input is a partially ordered set P, and solving the problem amounts to discovering an unknown linear extension of P, using pairwise comparisons. The information-theoretic lower bound on the number of comparisons needed in the worst case is log e(P), the binary logarithm of the number of linear extensions of P. In a breakthrough paper, Jeff Kahn and Jeong Han Kim (J. Comput. System Sci. 51 (3), 390-399, 1995) showed that there exists a polynomial-time algorithm for the problem achieving this bound up to a constant factor. Their algorithm invokes the ellipsoid algorithm at each iteration for determining the next comparison, making it impractical. We develop efficient algorithms for sorting under partial information. Like Kahn and Kim, our approach relies on graph entropy. However, our algorithms differ in essential ways from theirs. Rather than resorting to convex programming for computing the entropy, we approximate the entropy, or make sure it is computed only once, in a restricted class of graphs, permitting the use of a simpler algorithm. Specifically, we present: - an O(n^2) algorithm performing O(log n log e(P)) comparisons; - an O(n^2.5) algorithm performing at most (1+ epsilon) log e(P) + O_epsilon (n) comparisons; - an O(n^2.5) algorithm performing O(log e(P)) comparisons. All our algorithms can be implemented in such a way that their computational bottleneck is confined in a preprocessing phase, while the sorting phase is completed in O(q) + O(n) time, where q denotes the number of comparisons performed.
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arxiv:0911.0086
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The purpose of the given work is detailed research of toroidal shock wave movement process to the center of symmetry in air by normal atmosphere pressure. The wave is generated by plazma which is generated by a ring discharger.
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arxiv:0911.0099
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When a ferromagnet is deposited on the surface of a topological insulator the topologically protected surface state develops a gap and becomes a 2-dimensional quantum Hall liquid. We demonstrate that the Hall current in such a liquid, induced by an external electric field, can have a large effect on the magnetization dynamics of the ferromagnet by changing the effective anisotropy field. This change is dissipationless and may be substantial even in weakly spin-orbit coupled ferromagnets. We study the possibility of dissipationless current-induced magnetization reversal in monolayer-thin, insulating ferromagnets with a soft perpendicular anisotropy and discuss possible applications of this effect.
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arxiv:0911.0106
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We propose two algorithms to provide a full preliminary orbit of an Earth-orbiting object with a number of observations lower than the classical methods, such as those by Laplace and Gauss. The first one is the Virtual debris algorithm, based upon the admissible region, that is the set of the unknown quantities corresponding to possible orbits for objects in Earth orbit (as opposed to both interplanetary orbits and ballistic ones). A similar method has already been successfully used in recent years for the asteroidal case. The second algorithm uses the integrals of the geocentric 2-body motion, which must have the same values at the times of the different observations for a common orbit to exist. We also discuss how to account for the perturbations of the 2-body motion, e.g., the $J_2$ effect.
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arxiv:0911.0149
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Obvious view of distribution function of Markovian random evolution is found in terms of Bessel functions of n+1-th order.
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arxiv:0911.0165
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The phase diagram for the interacting fermions in weak coupling is described by the perturbative renormalization group equations. Due to the lack of analytic solutions for these coupled non-linear differential equations, it is rather subtle to tell which couplings are relevant or irrelevant. We propose a powerful classification scheme to build up the hierarchy of the relevant couplings by a scaling Ansatz found numerically. To demonstrate its superiority over the conventional classification for the relevant couplings, we apply this scheme to a controversial phase transition in the two-leg ladder and show that it should be a non-trivial crossover instead. The scaling Ansatz we propose here can classify the relevant couplings in hierarchical order without any ambiguity and can improve significantly how we interpret the numerical outcomes in general renormalization group methods.
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arxiv:0911.0166
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In orthogonal frequency-division multiplexing (OFDM) systems operating over rapidly time-varying channels, the orthogonality between subcarriers is destroyed leading to inter-carrier interference (ICI) and resulting in an irreducible error floor. In this paper, a new and low-complexity maximum {\em a posteriori} probability (MAP) detection algorithm is proposed for OFDM systems operating over rapidly time-varying multipath channels. The detection algorithm exploits the banded structure of the frequency-domain channel matrix whose bandwidth is a parameter to be adjusted according to the speed of the mobile terminal. Based on this assumption, the received signal vector is decomposed into reduced dimensional sub-observations in such a way that all components of the observation vector contributing to the symbol to be detected are included in the decomposed observation model. The data symbols are then detected by the MAP algorithm by means of a Markov chain Monte Carlo (MCMC) technique in an optimal and computationally efficient way. Computational complexity investigation as well as simulation results indicate that this algorithm has significant performance and complexity advantages over existing suboptimal detection and equalization algorithms proposed earlier in the literature.
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arxiv:0911.0183
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Theta 1 Ori E is a young, moderate mass binary system, a rarely observed case of spectral-type G-giants of about 3 Solar masses, which are still collapsing towards the main sequence. We have obtained high resolution X-ray spectra with Chandra and find that the system is very active and similar to coronal sources, having emission typical of magnetically confined plasma: a broad temperature distribution with a hot component and significant high energy continuum; narrow emission lines from H- and He-like ions, as well as a range of Fe ions, and relative luminosity, L_x/L_bol = 0.001. Density, while poorly constrained, is consistent with the low density limits as determined from Mg XI and Ne IX emission lines. Coronal elemental abundances are sub-Solar, with Ne being the highest at about 0.4 times Solar. We find a possible trend in Trapezium hot plasmas towards low relative abundances of Fe, O, and Ne, which is hard to explain in terms of the dust depletion scenarios of low-mass young stars. Variability was unusually low relative to other coronally active stars. The emission is similar to post main-sequence G-stars. Coronal structures could be compact or comparable to the dimensions of the stellar radii. We conclude that the X-rays in theta 1 Ori E are generated by a convective dynamo.
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arxiv:0911.0189
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We prove a central limit theorem for a general class of adaptive Markov Chain Monte Carlo algorithms driven by sub-geometrically ergodic Markov kernels. We discuss in detail the special case of stochastic approximation. We use the result to analyze the asymptotic behavior of an adaptive version of the Metropolis Adjusted Langevin algorithm with a heavy tailed target density.
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arxiv:0911.0221
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We study the implementation of quantum phase measurement in a superconducting circuit, where two Josephson phase qubits are coupled to the photon field inside a resonator. We show that the relative phase of the superposition of two Fock states can be imprinted in one of the qubits. The qubit can thus be used to probe and store the quantum coherence of two distinguishable Fock states of the single-mode photon field inside the resonator. The effects of dissipation of the photon field on the phase detection are investigated. We find that the visibilities can be greatly enhanced if the Kerr nonlinearity is exploited. We also show that the phase measurement method can be used to perform the Gauss sum factorization of numbers (${\geq} 10^4$) into a product of prime integers, as well as to precisely measure both the resonator's frequency and the nonlinear interaction strength. The largest factorizable number is mainly limited by the coherence time. If the relaxation time of the resonator were to be ${\sim} 10$ $\mu$s (${\sim} 1$ ms), then the largest factorizable number can be ${\geq} 10^4N$ (${\geq} 10^{7}N$), where $N$ is the number of photons in the resonator.
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arxiv:0911.0249
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We show that dimensional recurrence relation and analytical properties of the loop integrals as functions of complex variable $\mathcal{D}$ (space-time dimensionality) provide a regular way to derive analytical representations of loop integrals. The representations derived have a form of exponentially converging sums. Several examples of the developed technique are given.
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arxiv:0911.0252
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We examine the known curvature terms in the DBI part of the D-brane action under the T-duality transformation. Using the compatibility of the action with the standard rules of T-duality at the linear order as a guiding principle, we include the appropriate NS-NS $B$-field terms in the action and show that they reproduce the O(\alpha'^2) terms of the corresponding disk-level scattering amplitude.
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arxiv:0911.0255
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This paper proposes a new view to algorithms, Algorithms as defining dynamic systems. This view extends the traditional, deterministic view that an algorithm is a step by step procedure with nondeterminism. As a dynamic system can be designed by a set of its defining laws, it is also desirable to design an algorithm by a (possibly nondeterministic) set of defining laws. This observation requires some changes to algorithm development. We propose a two step approach, the first step is to design an algorithm via a set of defining laws of dynamic system. The second step is to translate these laws (written in a natural language) into a formal language such as linear logic.
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arxiv:0911.0397
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Adaptive control technique is adopted to synchronize two identical non-autonomous systems with unknown parameters in finite time. A virtual unknown parameter is introduced in order to avoid the unknown parameters from appearing in the controllers and parameters update laws. The Duffing equation and a gyrostat system are chosen as the numerical examples to show the validity of the present method.
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arxiv:0911.0457
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A Rydberg gas of NO entrained in a supersonic molecular beam releases electrons as it evolves to form an ultracold plasma. The size of this signal, compared with that extracted by the subsequent application of a pulsed electric field, determines the absolute magnitude of the plasma charge. This information, combined with the number density of ions, supports a simple thermochemical model that explains the evolution of the plasma to an ultracold electron temperature.
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arxiv:0911.0466
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Online learning algorithms have impressive convergence properties when it comes to risk minimization and convex games on very large problems. However, they are inherently sequential in their design which prevents them from taking advantage of modern multi-core architectures. In this paper we prove that online learning with delayed updates converges well, thereby facilitating parallel online learning.
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arxiv:0911.0491
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Over the recent years, IP and email spoofing gained much importance for security concerns due to the current changes in manipulating the system performance in different online environments. Intrusion Detection System (IDS) has been used to secure these environments for sharing their data over network and host based IDS approaches. However, the rapid growth of intrusion events over Internet and local area network become responsible for the distribution of different threats and vulnerabilities in the computing systems. The current signature detection approach used by IDS, detects unclear actions based on analyzing and describing the action patterns such as time, text, password etc and has been faced difficulties in updating information, detect unknown novel attacks, maintenance of an IDS which is necessarily connected with analyzing and patching of security holes, and the lack of information on user privileges and attack signature structure. Thus, this paper proposes an EADS (Exception agent detection system) for securing the header information carried by IP over online environments. The study mainly concerns with the deployment of new technique for detecting and eliminating the unknown threats attacks during the data sharing over online environments.
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arxiv:0911.0501
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The magnetization reversal in stripe-like exchange bias patterned $\rm Ni_{81}Fe_{19}/IrMn$ thin films was investigated by complementary inductive and high resolution magneto optical magnetometry, magneto optical Kerr microscopy, and polarized neutron reflectometry to clarify the effects of competing interfacial exchange bias and lateral interface contributions. Structures of varying ferromagnetic layer thickness and stripe period were analyzed systematically at the frozen-in domain state of oppositely aligned stripe magnetization. For all samples the mean magnetization of the magnetic hybrid structures was found to be aligned nearly orthogonally with respect to the stripe axis and the set exchange bias direction. Due to the interaction of interfacial coupling, exchange, and magneto-static energy contributions, the opening angle of neighboring stripe magnetizations increases with decreasing ferromagnetic layer thickness and increasing stripe period. The experimental observations are in agreement with an earlier proposed model for designing micro-patterned exchange bias films.
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arxiv:0911.0559
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We present two measures of distance between quantum processes based on the superfidelity, introduced recently to provide an upper bound for quantum fidelity. We show that the introduced measures partially fulfill the requirements for distance measure between quantum processes. We also argue that they can be especially useful as diagnostic measures to get preliminary knowledge about imperfections in an experimental setup. In particular we provide quantum circuit which can be used to measure the superfidelity between quantum processes. As the behavior of the superfidelity between quantum processes is crucial for the properties of the introduced measures, we study its behavior for several families of quantum channels. We calculate superfidelity between arbitrary one-qubit channels using affine parametrization and superfidelity between generalized Pauli channels in arbitrary dimensions. Statistical behavior of the proposed quantities for the ensembles of quantum operations in low dimensions indicates that the proposed measures can be indeed used to distinguish quantum processes.
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arxiv:0911.0567
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Based on a recent communication by the present authors the question of energy dissipation in magneto hydrodynamical waves in an inflating background in general relativity is examined. It is found that the expanding background introduces a sort of dragging force on the propagating wave such that unlike the Newtonnian case energy gets dissipated as it progresses. This loss in energy having no special relativistic analogue is, however, not mechanical in nature as in elastic wave. It is also found that the energy loss is model dependent and also depends on the number of dimensions.
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arxiv:0911.0591
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Results of a numerical simulation concerning the low-lying spectrum of four-dimensional N=1 SU(2) Supersymmetric Yang-Mills (SYM) theory on the lattice with light dynamical gluinos are reported. We use the tree-level Symanzik improved gauge action and Wilson fermions with stout smearing of the gauge links in the Wilson-Dirac operator. The configurations are produced with the Two-Step Polynomial Hybrid Monte Carlo (TS-PHMC) algorithm. We performed simulations on lattices up to a size of 24^3x48 at \beta=1.6. Using QCD units with the Sommer scale being set to r_0=0.5 fm, the lattice spacing is about a~0.09 fm, and the spatial extent of the lattice corresponds to 2.1 fm to control finite size effects. At the lightest simulated gluino mass our results indicate a mass for the lightest gluino-glue bound state, which is considerably heavier than the values obtained for its possible superpartners. Whether supermultiplets are formed remains to be studied in upcoming simulations.
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arxiv:0911.0595
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This is a course on Random Matrix Theory which includes traditional as well as advanced topics presented with an extensive use of classical logarithmic plasma analogy and that of the quantum systems of one-dimensional interacting fermions with inverse square interaction (Calogero-Sutherland model). Certain non-invariant random matrix ensembles are also considered with the emphasis on the eigenfunction statistics in them. The course can also be viewed as introduction to theory of localization where the (non-invariant) random matrix ensembles play a role of the toy models to illustrate functional methods based on super-vector/super-matrix representations.
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arxiv:0911.0639
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The exploration of extragalactic objects with long-baseline interferometers in the near-infrared has been very limited. Here we report successful observations with the Keck interferometer at K-band (2.2 um) for four Type 1 AGNs, namely NGC4151, Mrk231, NGC4051, and the QSO IRAS13349+2438 at z=0.108. For the latter three objects, these are the first long-baseline interferometric measurements in the infrared. We detect high visibilities (V^2 ~ 0.8-0.9) for all the four objects, including NGC4151 for which we confirm the high V^2 level measured by Swain et al.(2003). We marginally detect a decrease of V^2 with increasing baseline lengths for NGC4151, although over a very limited range, where the decrease and absolute V^2 are well fitted with a ring model of radius 0.45+/-0.04 mas (0.039+/-0.003 pc). Strikingly, this matches independent radius measurements from optical--infrared reverberations that are thought to be probing the dust sublimation radius. We also show that the effective radius of the other objects, obtained from the same ring model, is either roughly equal to or slightly larger than the reverberation radius as a function of AGN luminosity. This suggests that we are indeed partially resolving the dust sublimation region. The ratio of the effective ring radius to the reverberation radius might also give us an approximate probe for the radial structure of the inner accreting material in each object. This should be scrutinized with further observations.
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arxiv:0911.0666
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Upcoming gravitational wave (GW) detectors might detect a stochastic background of GWs potentially arising from many possible sources, including bubble collisions from a strongly first-order electroweak phase transition. We investigate whether it is possible to connect, via a semi-analytical approximation to the tunneling rate of scalar fields with quartic potentials, the GW signal through detonations with the parameters entering the potential that drives the electroweak phase transition. To this end, we consider a finite temperature effective potential similar in form to the Higgs potential in the Standard Model (SM). In the context of a semi-analytic approximation to the three dimensional Euclidean action, we derive a general approximate form for the tunneling temperature and the relevant GW parameters. We explore the GW signal across the parameter space describing the potential which drives the phase transition. We comment on the potential detectability of a GW signal with future experiments, and physical relevance of the associated potential parameters in the context of theories which have effective potentials similar in form to that of the SM. In particular we consider singlet, triplet, higher dimensional operators, and top-flavor extensions to the Higgs sector of the SM. We find that the addition of a temperature independent cubic term in the potential, arising from a gauge singlet for instance, can greatly enhance the GW power. The other parameters have milder, but potentially noticeable, effects.
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arxiv:0911.0687
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An overview of our current understanding of the formation and evolution of star clusters is given, with main emphasis on high-mass clusters. Clusters form deeply embedded within dense clouds of molecular gas. Left-over gas is cleared within a few million years and, depending on the efficiency of star formation, the clusters may disperse almost immediately or remain gravitationally bound. Current evidence suggests that a few percent of star formation occurs in clusters that remain bound, although it is not yet clear if this fraction is truly universal. Internal two-body relaxation and external shocks will lead to further, gradual dissolution on timescales of up to a few hundred million years for low-mass open clusters in the Milky Way, while the most massive clusters (> 10^5 Msun) have lifetimes comparable to or exceeding the age of the Universe. The low-mass end of the initial cluster mass function is well approximated by a power-law distribution, dN/dM ~ M^{-2}, but there is mounting evidence that quiescent spiral discs form relatively few clusters with masses M > 2 x 10^5 Msun. In starburst galaxies and old globular cluster systems, this limit appears to be higher, at least several x 10^6 Msun. The difference is likely related to the higher gas densities and pressures in starburst galaxies, which allow denser, more massive giant molecular clouds to form. Low-mass clusters may thus trace star formation quite universally, while the more long-lived, massive clusters appear to form preferentially in the context of violent star formation.
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arxiv:0911.0796
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Given a group G, the conjugacy problem in G is the problem of giving an effective procedure for determining whether or not two given elements f, g of G are conjugate, i.e. whether there exists h belonging to G with fh = hg. This paper is about the conjugacy problem in the group Diffeo(I) of all diffeomorphisms of an interval I in R. There is much classical work on the subject, solving the conjugacy problem for special classes of maps. Unfortunately, it is also true that many results and arguments known to the experts are difficult to find in the literature, or simply absent. We try to repair these lacunae, by giving a systematic review, and we also include new results about the conjugacy classification in the general case.
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arxiv:0911.0804
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Servo lag errors in adaptive optics lead to inaccurate compensation of wavefront distortions. An attempt has been made to predict future wavefronts using data mining on wavefronts of the immediate past to reduce these errors. Monte Carlo simulations were performed on experimentally obtained data that closely follows Kolmogorov phase characteristics. An improvement of 6% in wavefront correction is reported after data mining is performed. Data mining is performed in three steps (a) Data cube Segmentation (b) Polynomial Interpolation and (c) Wavefront Estimation. It is important to optimize the segment size that gives best prediction results. Optimization of the best predictable future helps in selecting a suitable exposure time.
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arxiv:0911.0822
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A large body of spectroscopic data on the cuprate high temperature superconductors (CHTSC) is reviewed in order to determine their order parameter. ASJ, INS, B2g Raman spectra, optical data, NIS "dips", ARPES "dips" and ARPES "kinks" all show the same excitation energy (40 meV for OP95 systems), proportional to the superconducting transition temperature, and it is therefore identified with the order parameter.
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arxiv:0911.0827
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We consider a finite group acting on a vector space and the corresponding skew group algebra generated by the group and the symmetric algebra of the space. This skew group algebra illuminates the resulting orbifold and serves as a replacement for the ring of invariant polynomials, especially in the eyes of cohomology. One analyzes the Hochschild cohomology of the skew group algebra using isomorphisms which convert between resolutions. We present an explicit chain map from the bar resolution to the Koszul resolution of the symmetric algebra which induces various isomorphisms on Hochschild homology and cohomology, some of which have appeared in the literature before. This approach unifies previous results on homology and cohomology of both the symmetric algebra and skew group algebra. We determine induced combinatorial cochain maps which invoke quantum differentiation (expressed by Demazure-BBG operators).
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arxiv:0911.0917
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In this article we first establish a complete characterization of Hardy's inequalities in $\mathbb{R}^n$ involving distances to different codimension subspaces. In particular the corresponding potentials have strong interior singularities. We then provide necessary and sufficient conditions for the validity of Hardy-Sobolev-Maz'ya inequalities with optimal Sobolev terms.
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arxiv:0911.0942
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We discuss the different dust components of a protoplanetary disk with a special emphasis on grain composition, size and structure. The paper will highlight the role dust grains play in protoplanetary disks, as well as observational results supporting this knowledge. First, the path dust travels from the interstellar medium into the CS disk is described. Then dust condensation sequences from the gas are introduced, to determine the most likely species that occur in a disk. The characteristics of silicates are handled in detail: composition, lattice structure, magnesium to iron ratio and spectral features. The other main dust-forming component of the interstellar medium, carbon, is presented in its many forms, from molecules to more complex grains. Observational evidence for PAHs is given for both young stars and solar system material. We show how light scattering theory and laboratory data can be used to provide the optical properties of dust grains. From the observer's point of view, we discuss how infrared spectra can be used to derive dust properties, and present the main spectral analysis methods currently used and their limitations. Observational results, determining the dust properties in protoplanetary disks, are given: first for the bright intermediate-mass Herbig Ae/Be stars, and then for the lower-mass Tauri stars and brown dwarfs. Here we present results from the space observatories ISO and Spitzer, as well as from the mid-infrared interferometer VLTI, and summarise the main findings. We discuss observational evidence for grain growth in both Herbig Ae/Be and T Tauri stars, and its relation with spectral type and dust settling. We conclude with an outlook on future space missions that will open new windows, towards longer wavelengths and even fainter objects.
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arxiv:0911.1010
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Although Luhmann formulated with modesty and precaution, for example in Die Wissenschaft der Gesellschaft (1990a, at pp. 412f.), that his theory claims to be a universal one because it is self-referential, the "operational closure" that follows from this assumption easily generates a problem for empirical research. Can a theory which considers society--and science as one of its subsystems--operationally closed, nevertheless contribute to the project of Enlightenment which Popper (1945) so vigorously identified as the driver of an open society? How can a theory which proclaims itself to be circular and universal nevertheless claim to celebrate "the triumph of the Enlightenment" Luhmann, (1990a, at p. 548)? Is the lack of an empirical program of research building on Luhmann's theory fortuitous or does it indicate that this theory should be considered as a philosophy rather than a heuristic for the explanation of operations in social systems?
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arxiv:0911.1041
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In a previous paper, the general approach for treatment of algebraic equations of different order in gravity theory was exposed, based on the important distinction between covariant and contravariant metric tensor components. In the present second part of the paper it has been shown that a multivariable cubic algebraic equation can also be parametrized by means of complicated, irrational and non-elliptic functions, depending on the elliptic Weierstrass function and its derivative. As a model example, the proposed before cubic algebraic equation for reparametrization invariance of the gravitational Lagrangian has been investigated. This is quite different from the standard algebraic geometry approach, where only the parametrization of two-dimensional cubic algebraic equations has been considered. Also, the possible applications in modern cosmological theories has been commented.
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arxiv:0911.1051
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We determine the polarization of the bulk $^{13}$C nuclear spin system in diamond produced by interaction with optically oriented nitrogen-vacancy (NV-) defect centers. $^{13}$C nuclei are polarized into the higher energy Zeeman state with a bulk-average polarization up to 5.2%, although local polarization may be higher. The kinetics of polarization are temperature independent, and occur within 5 minutes. Fluctuations in the dipolar field of the NV- center spin bath are identified as the mechanism by which nuclear spin transitions are induced near defect centers. Polarization is then transported to the bulk material via spin diffusion, which accounts for the observed kinetics of polarization. These results indicate control over the nuclear spin bath, a methodology to study dynamics of an NV- center ensemble, and application to sensitivity-enhanced NMR.
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arxiv:0911.1098
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We numerically show fractal Weyl law behavior in an open Hamiltonian system that is described by a smooth potential and which supports numerous above-barrier resonances. This behavior holds even relatively far away from the classical limit. The complex resonance wave functions are found to be localized on the fractal classical repeller.
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arxiv:0911.1109
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Let $f(z)=e^{-bz^2}f_1(z)$ where $b \geq 0$ and $f_1(z)$ is a real entire function of genus 0 or 1. We give a necessary and sufficient condition in terms of a sequence of inequalities for all of the zeros of $f(z)$ to be real. These inequalities are an extension of the classical Laguerre inequalities.
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arxiv:0911.1122
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Let $M$ be an $n$-dimensional complete simply connected Riemannian manifold with sectional curvature bounded above by a nonpositive constant $-\kappa^2$. Using the cone total curvature $TC(\Gamma)$ of a graph $\Gamma$ which was introduced by Gulliver and Yamada Math. Z. 2006, we prove that the density at any point of a soap film-like surface $\Sigma$ spanning a graph $\Gamma \subset M$ is less than or equal to $\frac{1}{2\pi}\{TC(\Gamma) - \kappa^{2}\area(p\mbox{$\times\hspace*{-0.178cm}\times$}\Gamma)\}$. From this density estimate we obtain the regularity theorems for soap film-like surfaces spanning graphs with small total curvature. In particular, when $n=3$, this density estimate implies that if \begin{eqnarray*} TC(\Gamma) < 3.649\pi + \kappa^2 \inf_{p\in M} \area({p\mbox{$\times\hspace*{-0.178cm}\times$}\Gamma}), \end{eqnarray*} then the only possible singularities of a piecewise smooth $(\mathbf{M},0,\delta)$-minimizing set $\Sigma$ is the $Y$-singularity cone. In a manifold with sectional curvature bounded above by $b^2$ and diameter bounded by $\pi/b$, we obtain similar results for any soap film-like surfaces spanning a graph with the corresponding bound on cone total curvature.
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arxiv:0911.1144
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We investigate consequences of the discovery that Fe II emission in quasars, one of the spectroscopic signatures of "Eigenvector 1", may originate in infalling clouds. Eigenvector 1 correlates with the Eddington ratio L/L_Edd so that Fe II/Hbeta increases as L/L_Edd increases. We show that the "force multiplier", the ratio of gas opacity to electron scattering opacity, is ~ 10^3 - 10^4 in Fe II-emitting gas. Such gas would be accelerated away from the central object if the radiation force is able to act on the entire cloud. As had previously been deduced, infall requires that the clouds have large column densities so that a substantial amount of shielded gas is present. The critical column density required for infall to occur depends on L/L_Edd, establishing a link between Eigenvector 1 and the Fe II/Hbeta ratio. We see predominantly the shielded face of the infalling clouds rather than the symmetric distribution of emitters that has been assumed. The Fe II spectrum emitted by the shielded face is in good agreement with observations thus solving several long-standing mysteries in quasar emission lines.
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arxiv:0911.1173
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Let X be a smooth projective curve of positive genus defined over a number field K. Assume given a Galois covering map x from X to the projective line over K and a place v of K. We introduce a local canonical height on the set of K_v-valued points of X associated to x as an integral with logarithmic integrand, generalizing Tate's local Neron function on an elliptic curve. The resulting global height can be viewed as a 'Mahler measure' associated to x. We prove that the local canonical height can be obtained by averaging, and taking a limit, over divisors of higher order Weierstrass points on X. This generalizes previous results by Everest-ni Fhlathuin and Szpiro-Tucker. Our construction of the local canonical height is an application of potential theory on Berkovich curves in the presence of a canonical measure.
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arxiv:0911.1271
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The capabilities of the ATLAS, CMS and LHCb detectors to reconstruct jets at forward rapidities (|\eta|> 3) in p-p collisions at the CERN Large Hadron Collider are reviewed. The QCD and Higgs physics motivations for such measurements are summarised. Details are given on studies that provide information on the parton structure and evolution at small values of fractional momenta in the proton.
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arxiv:0911.1273
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We obtain the existence of radially symmetric and decreasing solutions to a general class of quasi-linear elliptic problems by a nonsmooth version of a symmetric minimax principle recently obtained by Jean Van Schaftingen.
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arxiv:0911.1333
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We report the detection of a 115 day periodicity in SWIFT/XRT monitoring data from the ultraluminous X-ray source (ULX) NGC 5408 X-1. Our ongoing campaign samples its X-ray flux approximately twice weekly and has now achieved a temporal baseline of ~485 days. Periodogram analysis reveals a significant periodicity with a period of 115.5 +- 4 days. The modulation is detected with a significance of 3.2 e-4. The fractional modulation amplitude decreases with increasing energy, ranging from 0.13 above 1 keV to 0.24 below 1 keV. The shape of the profile evolves as well, becoming less sharply peaked at higher energies. The periodogram analysis is consistent with a periodic process, however, continued monitoring is required to confirm the coherent nature of the modulation. Spectral analysis indicates that NGC 5408 X-1 can reach 0.3 - 10 keV luminosities of ~2 e40 ergs/s. We suggest that, like the 62 day period of the ULX in M82 (X41.4+60), the periodicity detected in NGC 5408 X-1 represents the orbital period of the black hole binary containing the ULX. If this is true then the secondary can only be a giant or supergiant star.
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arxiv:0911.1339
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The exciting possibility of direct observation of QCD instantons in heavy-ion collisions has recently been proposed by Kharzeev. The underlying phenomenon, known as the chiral magnetic effect, may have been observed recently at RHIC, and a first principles calculation is needed to confirm and understand the results. The chiral magnetic effect is thought to be visible in the symmetric phase, at temperatures above the QCD critical temperature, and in the presence of an external magnetic field. We report on first 2+1 flavor, domain wall fermion, QCD+QED dynamical simulations above the critical temperature, in a fixed topological sector(s), which are used to study the electric charge separation produced by the effect.
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arxiv:0911.1348
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We propose large low-loss cross-phase modulation between two coupled surface polaritons propagating through a double electromagnetically-induced transparency medium situated close to a negative-index metamaterial. In particular a mutual $\pi$ phase shift is attainable between the two pulses at the single photon level.
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arxiv:0911.1372
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A subset V of GF(2)^n is a tile if GF(2)^n can be covered by disjoint translates of V. In other words, V is a tile if and only if there is a subset A of GF(2)^n such that V+A = GF(2)^n uniquely (i.e., v + a = v' + a' implies that v=v' and a=a' where v,v' in V and a,a' in A). In some problems in coding theory and hashing we are given a putative tile V, and wish to know whether or not it is a tile. In this paper we give two computational criteria for certifying that V is not a tile. The first involves impossibility of a bin-packing problem, and the second involves infeasibility of a linear program. We apply both criteria to a list of putative tiles given by Gordon, Miller, and Ostapenko in that none of them are, in fact, tiles.
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arxiv:0911.1388
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We discuss an approximation for the dynamic charge response of nonlinear spin-1/2 Luttinger liquids in the limit of small momentum. Besides accounting for the broadening of the charge peak due to two-holon excitations, the nonlinearity of the dispersion gives rise to a two-spinon peak, which at zero temperature has an asymmetric line shape. At finite temperature the spin peak is broadened by diffusion. As an application, we discuss the density and temperature dependence of the Coulomb drag resistivity due to long-wavelength scattering between quantum wires.
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arxiv:0911.1391
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The dynamic analysis of structural change in the organization of the sciences requires methodologically the integration of multivariate and time-series analysis. Structural change--e.g., interdisciplinary development--is often an objective of government interventions. Recent developments in multi-dimensional scaling (MDS) enable us to distinguish the stress originating in each time-slice from the stress originating from the sequencing of time-slices, and thus to locally optimize the trade-offs between these two sources of variance in the animation. Furthermore, visualization programs like Pajek and Visone allow us to show not only the positions of the nodes, but also their relational attributes like betweenness centrality. Betweenness centrality in the vector space can be considered as an indicator of interdisciplinarity. Using this indicator, the dynamics of the citation impact environments of the journals Cognitive Science, Social Networks, and Nanotechnology are animated and assessed in terms of interdisciplinarity among the disciplines involved.
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arxiv:0911.1437
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The journal set which provides a representation of nanoscience and nanotechnology at the interfaces among applied physics, chemistry, and the life sciences is developing rapidly because of the introduction of new journals. The relevant contributions of nations can be expected to change according to the representations of the relevant interfaces among journal sets. In the 2005 set the position of the USA decreased more than in the 2004-set, while the EU-27 gained in terms of its percentage of world share of citations. The tag "Y01N" which was newly added to the EU classification system for patents, allows for the visualization of national profiles of nanotechnology in terms of relevant patents and patent classes.
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arxiv:0911.1445
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The relation between the interaction parameters for fermions on the spatial lattice and the two-body $T$ matrix is discussed. The presented method allows determination of the interaction parameters through the relatively simple computational scheme which include the effect of finite lattice spacing. In particular the relation between the interaction parameters and the effective range expansion parameters is derived in the limit of large lattices.
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arxiv:0911.1457
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Almost 80 years have passed since Trumpler's analysis of the Galactic open cluster system laid one of the main foundations for understanding the nature and structure of the Milky Way. Since then, the open cluster system has been recognised as a key source of information for addressing a wide range of questions about the structure and evolution of our Galaxy. Over the last decade, surveys and individual observations from the ground and space have led to an explosion of astrometric, kinematic and multiwavelength photometric and spectroscopic open cluster data. In addition, a growing fraction of these data is often time-resolved. Together with increasing computing power and developments in classification techniques, the open cluster system reveals an increasingly clearer and more complete picture of our Galaxy. In this contribution, I review the observational properties of the Milky Way's open cluster system. I discuss what they can and cannot teach us now and in the near future about several topics such as the Galaxy's spiral structure and dynamics, chemical evolution, large-scale star formation, stellar populations and more.
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arxiv:0911.1459
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We present the most recent set of world averages for D0-D0bar mixing and CP violation parameters, as obtained by the Heavy Flavor Averaging Group from a global fit to various measurements. The values obtained for the mixing parameters when allowing for CP violation are x= (0.98 +0.24 -0.26)% and y= (0.83 +-0.16)%; the significance of mixing is 10.2 sigma. There is no evidence for CP violation at the current level of sensitivity.
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arxiv:0911.1464
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We prove in one go that each of the 4 families of Burniat surfaces with K^2 = 6,5,4, is a connected component of the moduli space of surfaces of general type. We prove also the rationality of each component. In the nodal case (one of the two families for K^2_S = 4) a very surprising and new phenomenon occurs. Both the moduli space for the minimal models and the Gieseker moduli space for canonical models are everywhere non reduced. But the nilpotence order is higher for the first.
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arxiv:0911.1466
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We discuss a general result of holomorphic extension of a real analytic function $f$ defined on the boundary $\partial D$ of a real analytic strictly convex subset $D\subset\subset \C^n$. We show that this follows from the hypothesis of separate holomorphic extension along stationary/extremal discs.
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arxiv:0911.1521
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For a given arithmetic scheme, in this paper we will introduce and discuss the monodromy action on a universal cover of the \'etale fundamental group and the monodromy action on an \emph{sp}-completion constructed by the graph functor, respectively; then by these results we will give a proof of the section conjecture of Grothendieck for arithmetic schemes.
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arxiv:0911.1523
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