1,831 research outputs found

    The uncoupling limit of identical Hopf bifurcations with an application to perceptual bistability

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    We study the dynamics arising when two identical oscillators are coupled near a Hopf bifurcation where we assume a parameter Ï”\epsilon uncouples the system at Ï”=0\epsilon=0. Using a normal form for N=2N=2 identical systems undergoing Hopf bifurcation, we explore the dynamical properties. Matching the normal form coefficients to a coupled Wilson-Cowan oscillator network gives an understanding of different types of behaviour that arise in a model of perceptual bistability. Notably, we find bistability between in-phase and anti-phase solutions that demonstrates the feasibility for synchronisation to act as the mechanism by which periodic inputs can be segregated (rather than via strong inhibitory coupling, as in existing models). Using numerical continuation we confirm our theoretical analysis for small coupling strength and explore the bifurcation diagrams for large coupling strength, where the normal form approximation breaks down

    Toward CP-even Neutrino Beam

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    The best method of measuring CP violating effect in neutrino oscillation experiments is to construct and use a neutrino beam made of an ideal mixture of Μˉe\bar{\nu}_e and Îœe\nu_e of monochromatic lines. The conceptual design of such a beam is described, together with how to measure the CP-odd quantity. We propose to exploit an accelerated unstable hydrogen-like heavy ion in a storage ring, whose decay has both electron capture and bound beta decay with a comparable fraction.Comment: 6 pages, 2 figures, Published versio

    Numerical modelling of concrete curing, regarding hydration and temperature phenomena

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    A numerical model that accounts for the hydration and aging phenomena during the early ages of concrete curing is presented in a format suitable for a finite element implementation. Assuming the percolation of water through the hydrates already formed as the dominant mechanism of cement hydration, the model adopts an internal variable called hydration degree, whose evolution law is easily calibrated and allows an accurate prediction of the hydration heat production. Compressive strength evolution is related to the aging degree, a concept that accounts for the influences of the hydration and curing temperature on the final mechanical properties of concrete. The model capabilities are illustrated by means of a wide set of experimental tests involving ordinary and high performance concretes, and through the simulation of the concrete curing on a viaduct deck of the Öresund Link

    Hydrogen-free SiCN films obtained by electron cyclotron resonance plasma: a study of composition, optical and luminescent properties

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    The Electrochemical Society, Inc. 2007. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in Journal of the Electrochemical Society Vol. 154 Issue 4 (2007): H325-H33

    Analytic Approximations for Three Neutrino Oscillation Parameters and Probabilities in Matter

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    The corrections to neutrino mixing parameters in the presence of matter of constant density are calculated systematically as series expansions in terms of the mass hierarchy \dm{21}/\dm{31}. The parameter mapping obtained is then used to find simple, but nevertheless accurate formulas for oscillation probabibilities in matter including CP-effects. Expressions with one to one correspondence to the vacuum case are derived, which are valid for neutrino energies above the solar resonance energy. Two applications are given to show that these results are a useful and powerful tool for analytical studies of neutrino beams passing through the Earth mantle or core: First, the ``disentanglement problem'' of matter and CP-effects in the CP-asymmetry is discussed and second, estimations of the statistical sensitivity to the CP-terms of the oscillation probabilities in neutrino factory experiments are presented.Comment: 17 pages, 3 figure

    Morphological and Molecular Characterization of Grapevine Accessions Known as Albillo

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    Twenty-eight accessions identified under the name of Albillo or cited as a synonym of this ancient Spanish grapevine variety were characterized using 43 morphological descriptors, four different isozyme systems (CO, ACPH, GOT, and SOD) and two Amplified Fragment Length Polymorphism (AFLP) primer combinations. Genetic similarity data resulting from these analyses allowed three different groups of Albillo to be distinguished that corresponded with geographical and historical origin of representative varieties: Turruntés, Malvasía de El Bierzo, and the classical Albillo de Madrid, related to the oldest Albillo ampelographical descriptions. In addition, homonyms as well as varieties incorrectly cited as Albillo synonyms were identified. To ensure accurate variety identification, association among historical descriptions based on morphological descriptors and molecular fingerprints was required. Isozymes proved to be useful markers for varietal identification. However, only AFLP allowed distinction among closely related varieties as well as the analysis of intravarietal variation.M.T.C. was funded by a Ministerio de Educación y Cultura contract; I.R., J.A.C., and J.C. were funded by predoctoral fellowships from the European Union, Instituto Nacional de Investigaciones Agrarias y Agroalimentarias, and Agencia Española de Cooperación Internacional, respectively. This research was funded in part by projects INIA SC96-010, SC94-092, and CM 07B-0010-1997. Support for research activity at the Centro Nacional de Biotecnología is provided by a CSIC-INIA specific agreement.Peer reviewe

    Characterization of genetic variation within table grape varieties (Vitis vinifera L.) based on AFLP markers

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    AFLPs were used to characterize a collection of 35 table grape varieties. A single AFLP reaction with a single combination of selective primers yielded an average of 50 polymorphic and scorable amplified bands in this collection and was enough to unequivocally identify each analyzed variety, Genetic similarity between different varieties was estimated, based on the results obtained with two primer combinations, to be between 0.65 and 0.90, while sibling varieties derived from the same cross showed a genetic similarity higher than 0.80, The analysis of several samples belonging to the same varieties, yet from different origins, showed stability of the AFLP patterns as to unequivocally and reproducibly identify them. Furthermore, some specific primer combinations detected a low level of variation that could be due to somatic variation and would be useful in clonal identification

    The role of matter density uncertainties in the analysis of future neutrino factory experiments

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    Matter density uncertainties can affect the measurements of the neutrino oscillation parameters at future neutrino factory experiments, such as the measurements of the mixing parameters Ξ13\theta_{13} and \deltacp. We compare different matter density uncertainty models and discuss the possibility to include the matter density uncertainties in a complete statistical analysis. Furthermore, we systematically study in which measurements and where in the parameter space matter density uncertainties are most relevant. We illustrate this discussion with examples that show the effects as functions of different magnitudes of the matter density uncertainties. We find that matter density uncertainties are especially relevant for large \stheta \gtrsim 10^{-3}. Within the KamLAND-allowed range, they are most relevant for the precision measurements of \stheta and \deltacp, but less relevant for ``binary'' measurements, such as for the sign of \ldm, the sensitivity to \stheta, or the sensitivity to maximal CP violation. In addition, we demonstrate that knowing the matter density along a specific baseline better than to about 1% precision means that all measurements will become almost independent of the matter density uncertainties.Comment: 21 pages, 7 figures, LaTeX. Final version to be published in Phys. Rev.

    Varietal diversity within grapevine accessions of cv. Tempranillo

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    Intra-varietal diversity of 31 accessions named as Tempranillo or described as synonyms of this representative Spanish grapevine variety was assessed using 48 morphological descriptors and 95 AFLP markers obtained using 2 primer combinations. We could identify homonyms as well as accessions belonging to varieties which, depending on their regional origin, are incorrectly cited as Tempranillo synonyms. Genetic analysis revealed a high level of genetic similarity between Tempranillo accessions (SG >0.97), which could correspond to three highly related genotypes. This narrow genetic variation supports a monophyletic origin of Tempranillo, and could be the result of rapid multiplication and distribution of a very low number of clones.

    Zygomycosis in Two Hematologic Cases

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    Zygomycosis are invasive mould infections, rarely diagnosed in hematologic patients. Most of the cases published are in patients with prolonged neutropenia, along with other risk factors such as the use of prior broad-spectrum antibiotics (including new antifungal agents, such as voriconazole), diabetes mellitus (with or without ketoacidosis), malnutrition, iron overload (with or without the use of deferoxamine). These infections have poor prognosis due to the involvement of vital anatomic structures and late diagnosis. Until recent years, the treatment was based on high doses of amphotericin B plus surgical debridement. Here we present two patients with hematologic diseases (one with leukemia, the second with aplastic anemia) with an impaired immune system and the diagnosis of zygomycosis. The survival of one of them was mainly due to early diagnosis and surgical debridement; unfortunately the second was misdiagnosed as an extensive ecchymosis due to thrombocytopenia and died with CNS involvement
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