55 research outputs found

    A semi-automatic parallelization tool for Java based on fork-join synchronization patterns

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    Because of the increasing availability of multi-core machines, clusters, Grids, and combinations of these environments, there is now plenty of computational power available for executing compute intensive applications. However, because of the overwhelming and rapid advances in distributed and parallel hardware and environments, today?s programmers are not fully prepared to exploit distribution and parallelism. In this sense, the Java language has helped in handling the heterogeneity of such environments, but there is a lack of facilities and tools to easily distributing and parallelizing applications. One solution to mitigate this problem and make some progress towards producing general tools seems to be the synthesis of semi-automatic parallelism and Parallelism as a Concern (PaaC), which allows parallelizing applications along with as little modifications on sequential codes as possible. In this paper, we discuss a new approach that aims at overcoming the drawbacks of current Java-based parallel and distributed development tools, which precisely exploit these new conceptsFil: Hirsch, Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Tandil. Instituto Superior de Ingenieria del Software; Argentina;Fil: Zunino, Alejandro. Consejo Nacional de Invest.cientif.y Tecnicas. Ctro Cientifico Tecnologico Conicet - Tandil. Instituto Superior de Ingenieria del Software;Fil: Mateos Diaz, Cristian Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Tandil. Instituto Superior de Ingenieria del Software

    Novelty Improves the Formation and Persistence of Memory in a Naturalistic School Scenario

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    One of the top challenges in education and neuroscience consists in translating laboratory results into strategies to improve learning and memory in teaching environments. In that sense, during the last two decades, researchers have discovered specific temporal windows around learning, during which the intervention with some experiences induces modulatory effects on the formation and/or persistence of memory. Based on these results, the aim of the present study was to design a specific strategy to improve the memory of students in a high-school scenario, by assessing the effect of a novel situation experienced close to learning. We found that the long-term memory about a geometrical figure was more precise in the group of students that faced a novel situation 1 h before or after learning the figure than the control group of students who did not face the novelty. This enhancement was probably triggered by processes acting on memory formation mechanisms that remained evident 45 days after learning, indicating that the improvement was sustained over time. In addition, our results showed that novelty no longer improved the memory if it was experienced 4 h before or after learning. However, far beyond this window of efficacy, when it was faced around 10 h after learning, the novel experience improved the memory persistence tested 7 days later. In summary, our findings characterized different temporal windows of the effectiveness of novelty acting on memory processing, providing a simple and inexpensive strategy that could be used to improve memory formation and persistence in high-school students.Fil: Ramírez Butavand, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; ArgentinaFil: Hirsch, Ian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; ArgentinaFil: Tomaiuolo, Micol. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; ArgentinaFil: Moncada, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; ArgentinaFil: Viola, Haydée. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular; ArgentinaFil: Ballarini, Fabricio Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; Argentin

    A Simulation-based Performance Evaluation of Heuristics for Dew Computing

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    The evolution of smartphones allows the continuous exploitation of computing resources. This increasingly applies also to distributed environments as exemplified through utilization of network router loads in edge computing and fog computing. Combining cloud computing and mobile smart devices in dew computing contexts enables new techniques for resource utilization, data collection and data processing. However, new challenges regarding job scheduling arise. Smartphones may be used in ad-hoc networks in this context, but their heterogeneity and energy usage must be considered. We propose novel heuristics for performance measuring of distributed computing systems integrated with mobile devices and compare them with previous heuristics in a simulation environment. Our results show an overall improvement in job completion and load balancing metrics compared to previous approaches. They highlight the usefulness of pursuing this research stream for aiming at industrial implementation and evaluation

    Tri-Bimaximal Neutrino Mixing, A4 and the Modular Symmetry

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    We formulate and discuss a 4-dimensional SUSY version of an A4 model for tri-bimaximal neutrino mixing which is completely natural. We also study the next-to-the-leading corrections and show that they are small, once the ratios of A4 breaking VEVs to the cutoff are fixed in a specified interval. We also point out an interesting way of presenting the A4 group starting from the modular group. In this approach, which could be interesting in itself as an indication on a possible origin of A4, the lagrangian basis where the symmetry is formulated coincides with the basis where the charged leptons are diagonal. If the same classification structure in A4 is extended from leptons to quarks, the CKM matrix coincides with the unit matrix in leading order and a study of non leading corrections shows that the departures from unity of the CKM matrix are far too small to accomodate the observed mixing angles.Comment: 21 pages, 1 figure; added section on a see-saw realization; version to appear on Nucl. Phys.

    Tri-Bimaximal Lepton Mixing and Leptogenesis

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    In models with flavour symmetries added to the gauge group of the Standard Model the CP-violating asymmetry necessary for leptogenesis may be related with low-energy parameters. A particular case of interest is when the flavour symmetry produces exact Tri-Bimaximal lepton mixing leading to a vanishing CP-violating asymmetry. In this paper we present a model-independent discussion that confirms this always occurs for unflavoured leptogenesis in type I see-saw scenarios, noting however that Tri-Bimaximal mixing does not imply a vanishing asymmetry in general scenarios where there is interplay between type I and other see-saws. We also consider a specific model where the exact Tri-Bimaximal mixing is lifted by corrections that can be parametrised by a small number of degrees of freedom and analyse in detail the existing link between low and high-energy parameters - focusing on how the deviations from Tri-Bimaximal are connected to the parameters governing leptogenesis.Comment: 29 pages, 6 figures; version 2: references added, minor correction

    A SUSY SU(5) Grand Unified Model of Tri-Bimaximal Mixing from A4

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    We discuss a grand unified model based on SUSY SU(5) in extra dimensions and on the flavour group A4xU(1) which, besides reproducing tri-bimaximal mixing for neutrinos with the accuracy required by the data, also leads to a natural description of the observed pattern of quark masses and mixings.Comment: 19 page

    New-physics contributions to the forward-backward asymmetry in B -> K* mu+ mu-

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    We study the forward-backward asymmetry (AFB) and the differential branching ratio (DBR) in B -> K* mu+ mu- in the presence of new physics (NP) with different Lorentz structures. We consider NP contributions from vector-axial vector (VA), scalar-pseudoscalar (SP), and tensor (T) operators, as well as their combinations. We calculate the effects of these new Lorentz structures in the low-q^2 and high-q^2 regions, and explain their features through analytic approximations. We find two mechanisms that can give a significant deviation from the standard-model predictions, in the direction indicated by the recent measurement of AFB by the Belle experiment. They involve the addition of the following NP operators: (i) VA, or (ii) a combination of SP and T (slightly better than T alone). These two mechanisms can be distinguished through measurements of DBR in B -> K* mu+ mu- and AFB in B -> K mu+ mu-.Comment: 33 pages, revtex, 9 figures. Paper originally submitted with the wrong figures. This is corrected in the replacement. An incorrect factor of 2 found in a formula. This is corrected and figures modified. Conclusions unchanged. Typos correcte

    A Simplest A4 Model for Tri-Bimaximal Neutrino Mixing

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    We present a see-saw A4A_4 model for Tri-Bimaximal mixing which is based on a very economical flavour symmetry and field content and still possesses all the good features of A4A_4 models. In particular the charged lepton mass hierarchies are determined by the A4×Z4A_4\times Z_4 flavour symmetry itself without invoking a Froggatt-Nielsen U(1) symmetry. Tri-Bimaximal mixing is exact in leading order while all the mixing angles receive corrections of the same order in next-to-the-leading approximation. As a consequence the predicted value of θ13\theta_{13} is within the sensitivity of the experiments which will take data in the near future. The light neutrino spectrum, typical of A4A_4 see-saw models, with its phenomenological implications, also including leptoproduction, is studied in detail.Comment: 20 pages, 2 figure

    Lepton Flavour Violation in Models with A4 Flavour Symmetry

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    We analyze lepton flavour violating transitions, leptonic magnetic dipole moments (MDMs) and electric dipole moments (EDMs) in a class of models characterized by the flavour symmetry A4 x Z3 x U(1)_{FN}, whose choice is motivated by the approximate tri-bimaximal mixing observed in neutrino oscillations. We construct the relevant low-energy effective Lagrangian where these effects are dominated by dimension six operators, suppressed by the scale M of new physics. All the flavour breaking effects are universally described by the vacuum expectation values of a set of spurions. We separately analyze both a supersymmetric and a general case. While the observed discrepancy delta a_mu in the anomalous MDM of the muon suggests M of order of a few TeV, several data require M above 10 TeV, in particular the limit on EDM of the electron. In the general case also the present limit on BR(mu -> e gamma) requires M >10 TeV, at least. The branching ratios for mu -> e gamma, tau -> mu gamma and tau -> e gamma are all expected to be of the same order. In the supersymmetric case the constraint from mu -> e gamma is softened and it can be satisfied by a smaller scale M. In this case both the observed delta a_mu and the current bound on BR(mu -> e gamma) can be satisfied, at the price of a rather small value for ||, of the order of a few percents, that reflects on a similar value for theta_{13}.Comment: 29 pages, 1 figur
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