4,800 research outputs found

    The Notostigmata, a new suborder of Acari

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    The following studies on this new suborder have been made on material included in the famous French Arachnologist E. Simon's rich collection and lent by him to Drs. H. J. Hansen and W. Sørensen. ..

    A magistrate's view on achieving compliance

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    This conference presentation was given as part of the Achieving Compliance with Road Traffic Law: What can enforcement, prosecution and sentencing contribute? Conference by Chris Hunt Cooke, Magistrate and Chairman of the Magistrates' Association Road Traffic Committee. The conference, jointly organised by PACTS and the Criminal Justice Research Centre with Brunel Law School, was hosted at Brunel University on the 13th June 2012, and was the first opportunity to review the evidence about how to improve compliance with road traffic law. Its aim was to set out the challenges facing the government over the next few years and the steps that need to be taken to improve levels of compliance on our roads. It took a wide look at the process of compliance from initial choices about enforcement through to the effectiveness of the court system

    Spectroscopy of Hadrons with b Quarks from Lattice NRQCD

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    Preliminary results from an extensive lattice calculation of the B, B_c, and \Upsilon spectrum at quenched \beta = 6.0 are presented. The study includes radially and orbitally excited mesons, and baryons containing b quarks. The b quarks are formulated using NRQCD; for light and c quarks, a tadpole-improved clover action is used.Comment: talk given at LATTICE98(heavyqk), 3 pages LaTeX, 2 Postscript figure

    The scaling dimension of low lying Dirac eigenmodes and of the topological charge density

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    As a quantitative measure of localization, the inverse participation ratio of low lying Dirac eigenmodes and topological charge density is calculated on quenched lattices over a wide range of lattice spacings and volumes. Since different topological objects (instantons, vortices, monopoles, and artifacts) have different co-dimension, scaling analysis provides information on the amount of each present and their correlation with the localization of low lying eigenmodes.Comment: Lattice2004(topology), Fermilab, June 21 - 26, 2004; 3 pages, 3 figure

    An apprach to generate large and small leptonic mixing angles

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    We take up the point of view that Yukawa couplings can be either 0 or 1, and the mass patterns of fermions are generated purely from the structure of the Yukawa matrices. We utilize such neutrino as well as charged leptonic textures which lead to (maximal) mixing angles of π/4\pi/4 in each sector for relevant transitions. The combined leptonic CKM mixing angles are π/4±π/4\pi/4 \pm \pi/4 which lead to very small sin22Θ\sin^2 2 \Theta relevant to solar neutrino and LSND experiments. We propose that on the other hand the absence of the charged leptonic partner of the sterile neutrino maintains the angle π/4\pi/4 from the neutrino sector for the transition νμνs\nu_\mu \leftrightarrow \nu_s and hence atmospheric neutrino anomaly is explained through maximal mixing

    Canonical General Relativity on a Null Surface with Coordinate and Gauge Fixing

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    We use the canonical formalism developed together with David Robinson to st= udy the Einstein equations on a null surface. Coordinate and gauge conditions = are introduced to fix the triad and the coordinates on the null surface. Toget= her with the previously found constraints, these form a sufficient number of second class constraints so that the phase space is reduced to one pair of canonically conjugate variables: \Ac_2\and\Sc^2. The formalism is related to both the Bondi-Sachs and the Newman-Penrose methods of studying the gravitational field at null infinity. Asymptotic solutions in the vicinity of null infinity which exclude logarithmic behavior require the connection to fall off like 1/r31/r^3 after the Minkowski limit. This, of course, gives the previous results of Bondi-Sachs and Newman-Penrose. Introducing terms which fall off more slowly leads to logarithmic behavior which leaves null infinity intact, allows for meaningful gravitational radiation, but the peeling theorem does not extend to Ψ1\Psi_1 in the terminology of Newman-Penrose. The conclusions are in agreement with those of Chrusciel, MacCallum, and Singleton. This work was begun as a preliminary study of a reduced phase space for quantization of general relativity.Comment: magnification set; pagination improved; 20 pages, plain te

    Generalized stochastic Schroedinger equations for state vector collapse

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    A number of authors have proposed stochastic versions of the Schr\"odinger equation, either as effective evolution equations for open quantum systems or as alternative theories with an intrinsic collapse mechanism. We discuss here two directions for generalization of these equations. First, we study a general class of norm preserving stochastic evolution equations, and show that even after making several specializations, there is an infinity of possible stochastic Schr\"odinger equations for which state vector collapse is provable. Second, we explore the problem of formulating a relativistic stochastic Schr\"odinger equation, using a manifestly covariant equation for a quantum field system based on the interaction picture of Tomonaga and Schwinger. The stochastic noise term in this equation can couple to any local scalar density that commutes with the interaction energy density, and leads to collapse onto spatially localized eigenstates. However, as found in a similar model by Pearle, the equation predicts an infinite rate of energy nonconservation proportional to δ3(0)\delta^3(\vec 0), arising from the local double commutator in the drift term.Comment: 24 pages Plain TeX. Minor changes, some new references. To appear in Journal of Physics

    Fourth order indirect integration method for black hole perturbations: even modes

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    On the basis of a recently proposed strategy of finite element integration in time domain for partial differential equations with a singular source term, we present a fourth order algorithm for non-rotating black hole perturbations in the Regge-Wheeler gauge. Herein, we address even perturbations induced by a particle plunging in. The forward time value at the upper node of the (r,t)(r^*,t) grid cell is obtained by an algebraic sum of i) the preceding node values of the same cell, ii) analytic expressions, related to the jump conditions on the wave function and its derivatives, iii) the values of the wave function at adjacent cells. In this approach, the numerical integration does not deal with the source and potential terms directly, for cells crossed by the particle world line. This scheme has also been applied to circular and eccentric orbits and it will be object of a forthcoming publication.Comment: This series of papers deals with EMRI for LISA. With the respect to the v1 version, the algorithm has been improved; convergence tests and references have been added; v2 is composed by 23 pages, and 6 figures. Paper accepted by Class. Quantum Gravity for the special issue on Theory Meets Data Analysis at Comparable and Extreme Mass Ratios (Capra and NRDA) at Perimeier Institute in June 201
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