615 research outputs found

    Mean-Field Approximation to the Master Equation for Sympathetic Cooling of Trapped Bosons

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    We use the mean-field approximation to simplify the master equation for sympathetic cooling of Bosons. For the mean single-particle occupation numbers, this approach yields the same equations as the factorization assumption introduced in an erlier paper. The stationary or equilibrium solution of the resulting master equation for the one-body density matrix shows that the mean-field approximation breaks down whenever the fraction of condensate Bosons exceeds ten percent or so of the total. Using group-theoretical methods, we also solve the time-dependent master equation for the one-body density matrix. Given the time dependence of the mean single-particle occupation numbers, this solution is obtained by quadratures. It tends asymptotically towards the equilibrium solution.Comment: submitted to PR

    Main characteristics and genesis of the Vale de Pães skarn (Cuba-Vidigueira, Ossa Morena Zone, Portugal)

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    The Vale de Pães (Cuba-Vidigueira) mineralisation is composed of magnetite ± sulphides and hosted in a Pre-Variscan metamorphic sequence intruded by igneous rocks belonging to the Beja Igneous Complex. Its mineral and chemical features are compatible with a zoned Fe-skarn: Mg-rich (Fo + Di90, oxidised) and Ca-rich (Grs + Di81-39, oxidised or relatively reduced). In the Fe-Mg skarn, magnetite deposition occurred along with the anhydrous mineral assemblage at ≈ 600 °C; sulphides precipitated from the retrograde stage onset (≤ 550 °C) and during the hydrated and carbonate phases formation period (< 420 °C). In the Fe-Ca skarn, magnetite precipitated during the retrograde stage (< 550 °C) together with the hydrated mineral association, and was followed by sulphides at ≈ 400°C. The mineralising process involved moderate-high salinity fluids and was controlled by variations in redox potential and pH.info:eu-repo/semantics/publishedVersio

    Principales características y génesis del skarn de Vale de Pães (Cuba-Vidigueira, Ossa Morena Zone, Portugal)

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    The Vale de Pães (Cuba-Vidigueira) mineralisation is composed of magnetite ± sulphides and hosted in a Pre-Variscan metamorphic sequence intruded by igneous rocks belonging to the Beja Igneous Complex. Its mineral and chemical features are compatible with a zoned Fe-skarn: Mg-rich (Fo + Di90, oxidised) and Ca-rich (Grs + Di81-39, oxidised or relatively reduced). In the Fe-Mg skarn, magnetite deposition occurred along with the anhydrous mineral assemblage at ≈ 600 °C; sulphides precipitated from the retrograde stage onset (≤ 550 °C) and during the hydrated and carbonate phases formation period (< 420 °C). In the Fe-Ca skarn, magnetite precipitated during the retrograde stage (< 550 °C) together with the hydrated mineral association, and was followed by sulphides at ≈ 400°C. The mineralising process involved moderate-high salinity fluids and was controlled by variations in redox potential and pH.La mineralización del Vale de Pães (Cuba-Vidigueira), compuesta de magnetita ± sulfuros, se produce dentro de una secuencia metamórfica ante-Varisca intruida por el Complejo Ígneo de Beja (Beja Igneous Complex). Sus características químicas y mineralógicas son consistentes con un skarn de Fe zonificado: rico en Mg (Fo + Di≈90, oxidado) y rico en Ca (Grs + Di81-39, oxidado o relativamente reducido). En el skarn de Fe-Mg, la deposición de magnetita acompaña a la paragénesis mineral anhidra (≈ 600 °C); la precipitación de sulfuros se produce desde el comienzo de la etapa retrógrada (≤ 550 °C) y continuó durante la formación de fases hidratadas y carbonatadas (< 420 °C). En el skarn de Fe-Ca, la magnetita se genera en la fase de retroceso (< 550 °C), en relación con la asociación de minerales hidratados, seguido de sulfuro (≈ 400 °C). El proceso de mineralización de los fluidos de salinidad moderada-alta era controlado por los cambios en el potencial redox y el pH

    Remembering Parotitis in SARS-CoV-2 era

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    New 2019-Coronavirus (SARS-CoV-2) pandemic is presenting daily diagnostic challenges to emergency departments (ED) doctors, especially as an increasing number of atypical clinical presentations have been reported, including acute sialadenitis (most of parotid). We present a case of a 46-year-old obese caucasian woman, with no relevant medical history, that presented in ED with complaints suggesting parotitis, with normal laboratory tests, at first with no virus isolation, confirmed by computed tomography. One week later, anosmia and dysgeusia were notice, and SARS-CoV-2 was tested and confirmed. Authors want to alert that SARS-CoV-2 should be excluded as parotitis etiology, highly important, especially in this pandemic phase, as a way of transmission controinfo:eu-repo/semantics/publishedVersio

    Modelling the Recoherence of Mesoscopic Superpositions in Dissipative Environments

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    A model is presented to describe the recently proposed experiment (J. Raimond, M. Brune and S. Haroche Phys. Rev. Lett {\bf 79}, 1964 (1997)) where a mesoscopic superposition of radiation states is prepared in a high-Q cavity which is coupled to a similar resonator. The dynamical coherence loss of such state in the absence of dissipation is reversible and can in principle be observed. We show how this picture is modified due to the presence of the environmental couplings. Analytical expressions for the experimental conditional probabilities and the linear entropy are given. We conclude that the phenomenon can still be observed provided the ratio between the damping constant and the inter-cavities coupling does not exceed about a few percent. This observation is favored for superpositions of states with large overlap.Comment: 13 pages, 6 figure

    Papéis de liderança de Quinn: um estudo realizado em serviços de saúde portugueses com recurso à análise factorial confirmatória

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    Purpose: To assess the psychometric properties of Quinn’s leadership questionnaire (CFV questionnaire; 1988) in Portuguese health services. Design: Cross-sectional study, using Quinn’s leadership questionnaire, administered to registered nurses and physicians in Portuguese health services (N = 687). Method: Self-administered survey applied to two samples. In the first sample (convenience; N = 249 Portuguese health professionals), exploratory factor and reliability analyses were performed to the CFV questionnaire. In the second sample (stratified; N = 50 surgical units of 33 Portuguese hospitals), confirmatory factor analyses were performed using LISREL 8.80. Findings: In the first sample, an eight-factor solution emerged accounting for 65.46% of the total variance, in an interpretable factor structure (loadings> .50), with Cronbach’s ? greater than .79. This factor structure, replicated in the second sample, showed reasonable goodness-of-fit of the model to each of the leadership roles, that is, to the eight quadrants and global model. Overall, the models showed nomological validity, with scores between good and acceptable (.235 < x2/df < 2.055 and .00 < RMSEA < .077). Conclusions: Quinn’s leadership questionnaire showed good reliability and validity for the eight leadership roles, proving to be suitable for use in health care/hospital settings.info:eu-repo/semantics/publishedVersio
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