1,388 research outputs found

    Mesoscopic, Non-equilibrium Fluctuations of Inhomogeneous Electronic States in Manganites

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    By using the dark-field real-space imaging technique of transmission electron microscopy (TEM), we have observed slow 200 A-scale fluctuations of charge-ordered (CO) phase in mixed-valent manganites under a strong electron beam irradiation. In addition to these unusual fluctuations of the CO phase, we observed the switching-type fluctuations of electrical resistivity in the same sample, which were found to be as large as several percents. Systematic analysis indicates that these two different types of fluctuations with a similar time scale of the order of seconds are interconnected through a meta-stable insulating charge-disordered state. Current dependence of the fluctuations suggests a non-equilibrium nature of this slow dynamics.Comment: To appear in Europhysics Letter

    Deterministic models of quantum fields

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    Deterministic dynamical models are discussed which can be described in quantum mechanical terms. -- In particular, a local quantum field theory is presented which is a supersymmetric classical model. The Hilbert space approach of Koopman and von Neumann is used to study the classical evolution of an ensemble of such systems. Its Liouville operator is decomposed into two contributions, with positive and negative spectrum, respectively. The unstable negative part is eliminated by a constraint on physical states, which is invariant under the Hamiltonian flow. Thus, choosing suitable variables, the classical Liouville equation becomes a functional Schroedinger equation of a genuine quantum field theory. -- We briefly mention an U(1) gauge theory with ``varying alpha'' or dilaton coupling where a corresponding quantized theory emerges in the phase space approach. It is energy-parity symmetric and, therefore, a prototype of a model in which the cosmological constant is protected by a symmetry.Comment: 6 pages; synopsis of hep-th/0510267, hep-th/0503069, hep-th/0411176 . Talk at Constrained Dynamics and Quantum Gravity - QG05, Cala Gonone (Sardinia, Italy), September 12-16, 2005. To appear in the proceeding

    Mapa de la Mutilación Genital Femenina en España 2016

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    Esta publicación forma parte del Proyecto «La prevención de la Mutilación Genital Femenina (MGF) en España», apoyado por el Ministerio de Empleo y Seguridad Social (MEYSS) y cofinanciado por el Fondo de Asilo, Migración e Integración (FAMI). Su contenido es responsabilidad exclusiva de los autores y no refleja necesariamente la opinión del MEYSS

    On two-dimensional surface attractors and repellers on 3-manifolds

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    We show that if f:M3M3f: M^3\to M^3 is an AA-diffeomorphism with a surface two-dimensional attractor or repeller B\mathcal B and MB2 M^2_ \mathcal B is a supporting surface for B \mathcal B, then B=MB2\mathcal B = M^2_{\mathcal B} and there is k1k\geq 1 such that: 1) MB2M^2_{\mathcal B} is a union M12...Mk2M^2_1\cup...\cup M^2_k of disjoint tame surfaces such that every Mi2M^2_i is homeomorphic to the 2-torus T2T^2. 2) the restriction of fkf^k to Mi2M^2_i (i{1,...,k})(i\in\{1,...,k\}) is conjugate to Anosov automorphism of T2T^2

    Desensitizing Inflation from the Planck Scale

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    A new mechanism to control Planck-scale corrections to the inflationary eta parameter is proposed. A common approach to the eta problem is to impose a shift symmetry on the inflaton field. However, this symmetry has to remain unbroken by Planck-scale effects, which is a rather strong requirement on possible ultraviolet completions of the theory. In this paper, we show that the breaking of the shift symmetry by Planck-scale corrections can be systematically suppressed if the inflaton field interacts with a conformal sector. The inflaton then receives an anomalous dimension in the conformal field theory, which leads to sequestering of all dangerous high-energy corrections. We analyze a number of models where the mechanism can be seen in action. In our most detailed example we compute the exact anomalous dimensions via a-maximization and show that the eta problem can be solved using only weakly-coupled physics.Comment: 34 pages, 3 figures

    Étude a méthodes mixtes explorant les connaissances, les attitudes et les practiques des professionels/lles de santé en matière de mutilation génital féminine en Casamance, Sénégal

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    Ajudes: Projet financé par: Garapenerako Lankidetzaren Euskal Agentzia / Agencia Vasca de Cooperación para el Desarrollo (Agence Basque de Coopération au Développement

    Quantum chromodynamics with advanced computing

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    We survey results in lattice quantum chromodynamics from groups in the USQCD Collaboration. The main focus is on physics, but many aspects of the discussion are aimed at an audience of computational physicists.Comment: 17 pp. Featured presentation at Scientific Discovery with Advanced Computing, July 13-17, Seattl

    Using informative behavior to increase engagement while learning from human reward

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    In this work, we address a relatively unexplored aspect of designing agents that learn from human reward. We investigate how an agent’s non-task behavior can affect a human trainer’s training and agent learning. We use the TAMER framework, which facilitates the training of agents by human-generated reward signals, i.e., judgements of the quality of the agent’s actions, as the foundation for our investigation. Then, starting from the premise that the interaction between the agent and the trainer should be bi-directional, we propose two new training interfaces to increase a human trainer’s active involvement in the training process and thereby improve the agent’s task performance. One provides information on the agent’s uncertainty which is a metric calculated as data coverage, the other on its performance. Our results from a 51-subject user study show that these interfaces can induce the trainers to train longer and give more feedback. The agent’s performance, however, increases only in response to the addition of performance-oriented information, not by sharing uncertainty levels. These results suggest that the organizational maxim about human behavior, “you get what you measure”—i.e., sharing metrics with people causes them to focus on optimizing those metrics while de-emphasizing other objectives—also applies to the training of agents. Using principle component analysis, we show how trainers in the two conditions train agents differently. In addition, by simulating the influence of the agent’s uncertainty–informative behavior on a human’s training behavior, we show that trainers could be distracted by the agent sharing its uncertainty levels about its actions, giving poor feedback for the sake of reducing the agent’s uncertainty without improving the agent’s performance

    A randomized open-label trial on the use of budesonide/formoterol (Symbicort®) as an alternative reliever medication for mild to moderate asthmatic attacks

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    BACKGROUND Conventionally, a nebulized short-acting β-2 agonist like salbutamol is often used as the reliever in acute exacerbations of asthma. However, recent worldwide respiratory outbreaks discourage routine use of nebulization. Previous studies have shown that combined budesonide/formoterol (Symbicort®, AstraZeneca) is effective as both a maintenance and reliever anti-asthmatic medication. METHODS We performed a randomized, open-label study from March until August 2011 to compare the bronchodilatory effects of Symbicort® vs. nebulized salbutamol in acute exacerbation of mild to moderate asthmatic attack in an emergency department. Initial objective parameters measured include the oxygen saturation, peak expiratory flow rate (PEFR) and respiratory rate. During clinical reassessment, subjective parameters [i.e., Visual Analog Scale (VAS) and 5-point Likert scale of breathlessness] and the second reading of the objective parameters were measured. For the 5-point Likert scale, the patients were asked to describe their symptom relief as 1, much worse; 2, a little worse; 3, no change; 4, a little better; 5, much better. RESULTS Out of the total of 32 patients enrolled, 17 patients (53%) were randomized to receive nebulized salbutamol and 15 (47%) to receive Symbicort®. For both treatment arms, by using paired t- and Wilcoxon signed rank tests, it was shown that there were statistically significant improvements in oxygen saturation, PEFR and respiratory rate within the individual treatment groups (pre- vs. post-treatment). Comparing the effects of Symbicort® vs. nebulized salbutamol, the average improvement of oxygen saturation was 1% in both treatment arms (p = 0.464), PEFR 78.67 l/min vs. 89.41 l/min, respectively (p = 0.507), and respiratory rate 2/min vs. 2/min (p = 0.890). For subjective evaluation, all patients reported improvement in the VAS (average 2.45 cm vs. 2.20 cm), respectively (p = 0.765). All patients in both treatment arms reported either "a little better" or "much better" on the 5-point Likert scale, with none reporting "no change" or getting worse. CONCLUSION This study suggests that there is no statistical difference between using Symbicort® vs. nebulized salbutamol as the reliever for the first 15 min post-intervention

    Higgs compositeness in Sp(2N) gauge theories – Determining the low-energy constants with lattice calculations

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    As a first step towards a quantitative understanding of the SU(4)/Sp(4) compositeHiggs model through lattice calculations, we discuss the low energy eective fieldtheory resulting from the SU(4) ! Sp(4) global symmetry breaking pattern. We thenconsider an Sp(4) gauge theory with two Dirac fermion flavours in the fundamental representationon a lattice, which provides a concrete example of the microscopic realisationof the SU(4)/Sp(4) composite Higgs model. For this system, we outline a programmeof numerical simulations aiming at the determination of the low-energy constants of theeective field theory and we test the method on the quenched theory. We also report earlyresults from dynamical simulations, focussing on the phase structure of the lattice theoryand a calculation of the lowest-lying meson spectrum at coarse lattice spacing
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