752 research outputs found

    An exact master equation for the system-reservoir dynamics under the strong coupling regime and non-Markovian dynamics

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    In this paper we present a method to derive an exact master equation for a bosonic system coupled to a set of other bosonic systems, which plays the role of the reservoir, under the strong coupling regime, i.e., without resorting to either the rotating-wave or secular approximations. Working with phase-space distribution functions, we verify that the dynamics are separated in the evolution of its center, which follows classical mechanics, and its shape, which becomes distorted. This is the generalization of a result by Glauber, who stated that coherent states remain coherent under certain circumstances, specifically when the rotating-wave approximation and a zero-temperature reservoir are used. We show that the counter-rotating terms generate fluctuations that distort the vacuum state, much the same as thermal fluctuations.Finally, we discuss conditions for non-Markovian dynamics

    Ornithological bibliography of the Azores

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    Only scientific publications up to 1980 are included in this bibliography. Other old narrations containing information on Azorean ornithology are being assembled for future publication. Certain unpublished works will also be dealt with. The part for consultation has been arranged in three sections. The first presents a numbered list of papers and books in chronological order up to 1980. Last minute alterations obliged us to eliminate some items and to use «bis» for repeated numbers in some cases. The second section consists of the list of papers under their authors in alphabetical order. Finally, the third section consists of an index of the scientific names of the species cited. The index contains three types of entries: - The names of the genera, in capital letters, followed by the specific and subspecific names, which lead to their numbers in the chronological list. The latter are accompanied by the relevant page numbers, in brackets. - The names of the species, in small letters in bold-faced type, lead to the names of the genera. - The names of the subspecies, in normal small letters, lead to the genera and species. Example: Fringilla coelebs moreletti entered under FRINGILLA, coelebs and moreletti, with the bibliographical references only under the complete name. Papers of Nºs. 17, 41, 72, 74, 76 have not been consulted by us; all other works are available in our library

    Heterogeneidade da relação entre produtividade da soja e severidade da ferrugem asiática: uma análise exploratória.

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    This work aimed to conduct an exploratory, prior to meta-analysis, assessment of the heterogeneity of the linear relationship between soybean yield (Y) and the severity (X) of a foliar fungal disease (soybean rust) from 144 fungicide trials conducted in five years and 45 locations in Brazil. We used graphical analysis to explore the within- and between-trial variability of model parameter estimates (effect sizes) and summary measures for model goodness-of-fit and influence analysis. In the estimation of the weighted mean regression coefficients, following the metaanalysis concept, we propose a method that takes into account the magnitude of influence measures as well as the uncertainties of parameters estimates, usually the inverse of the standard error of for the parameter estimate. High between-trial heterogeneity was observed for parameter estimates, standard errors (within trial variability), determination coefficient and influence measures. Graphical analysis suggested influence of timing of disease onset and control yield class on model slope, which will be quantified further using a meta-analytical approach

    Hypersonic jets in astrophysical conditions: focus on spreading and asymmetric stability properties

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    High Mach number jets emanating from young stars show remarkable collimation, low opening angle and resilience against the growth of instabilities, especially the asymmetric ones. In recent laboratory experiments instances of asymmetric three-dimensional low amplitude long waves aligned with the jet axis were observed Belan et al (2013 Astron. Astrophys. 554 A99). To explore the collimation, spreading, and asymmetric stability properties of hypersonic jets we carried out laboratory experiments and numerical simulations in two and three spatial dimensions. We find that laboratory hydrodynamic jets with high Mach numbers remain collimated, for hundreds of jet radii in length and maintain low opening angles. These findings are confirmed by 3D numerical simulations carried out after time-dependent, asymmetric perturbations are applied at the jet inlet. Both experimental and perturbed simulated jets show non-axial modes with long wavelengths, whose growth does not disrupt the jet in the domain considered

    Métodos probabilísticos para quantificar a influência do El Niño/oscilação sul sobre o risco de epidemias.

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    Neste trabalho, apresentamos e discutimos as vantagens e limitações de métodos estatísticos paramétricos e semi-paramétricos para a caracterização da influência do fenômeno El Nino/Oscilação Sul (ENOS) sobre o risco de epidemias de doenças de plantas. Foram utilizados dados simulados de um índice de severidade da ferrugem asiática em soja para Rosário do Sul, RS, local previamente identificado como passível da influência de ENOS na precipitação pluvial no período da safra. A influência ENOS sobre a produtividade agrícola e outras variáveis dependentes da precipitação pluviométrica, como a severidade de doenças, é bem conhecida e documentada em todo o mundo. No entanto, o uso rigoroso de abordagens probabilísticas inferenciais para quantificação da influência de indicadores climáticos sobre o de risco de epidemias ainda é raro

    Electromagnetically induced transparency and dynamic Stark effect in coupled quantum resonators

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    In this work we reproduce the phenomenology of the electromagnetically induced transparency and dynamic Stark effect in a dissipative system composed by two coupled bosonic fields under linear and nonlinear amplification process. Such a system can be used as a quantum switch in networks of oscillators

    Hypersonic jets in astrophysical conditions: focus on spreading and asymmetric stability properties

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    High Mach number jets emanating from young stars show remarkable collimation, low opening angle and resilience against the growth of instabilities, especially the asymmetric ones. In recent laboratory experiments instances of asymmetric three-dimensional low amplitude long waves aligned with the jet axis were observed Belan et al (2013 Astron. Astrophys. 554 A99). To explore the collimation, spreading, and asymmetric stability properties of hypersonic jets we carried out laboratory experiments and numerical simulations in two and three spatial dimensions. We find that laboratory hydrodynamic jets with high Mach numbers remain collimated, for hundreds of jet radii in length and maintain low opening angles. These findings are confirmed by 3D numerical simulations carried out after time-dependent, asymmetric perturbations are applied at the jet inlet. Both experimental and perturbed simulated jets show non-axial modes with long wavelengths, whose growth does not disrupt the jet in the domain considered
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