3,578 research outputs found

    Can we always get the entanglement entropy from the Kadanoff-Baym equations? The case of the T-matrix approximation

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    We study the time-dependent transmission of entanglement entropy through an out-of-equilibrium model interacting device in a quantum transport set-up. The dynamics is performed via the Kadanoff-Baym equations within many-body perturbation theory. The double occupancy <n^R↑n^R↓>< \hat{n}_{R \uparrow} \hat{n}_{R \downarrow} >, needed to determine the entanglement entropy, is obtained from the equations of motion of the single-particle Green's function. A remarkable result of our calculations is that <n^R↑n^R↓>< \hat{n}_{R \uparrow} \hat{n}_{R \downarrow} > can become negative, thus not permitting to evaluate the entanglement entropy. This is a shortcoming of approximate, and yet conserving, many-body self-energies. Among the tested perturbation schemes, the TT-matrix approximation stands out for two reasons: it compares well to exact results in the low density regime and it always provides a non-negative <n^R↑n^R↓>< \hat{n}_{R \uparrow} \hat{n}_{R \downarrow} >. For the second part of this statement, we give an analytical proof. Finally, the transmission of entanglement across the device is diminished by interactions but can be amplified by a current flowing through the system.Comment: 6 pages, 6 figure

    Real-Time Context-Aware Microservice Architecture for Predictive Analytics and Smart Decision-Making

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    The impressive evolution of the Internet of Things and the great amount of data flowing through the systems provide us with an inspiring scenario for Big Data analytics and advantageous real-time context-aware predictions and smart decision-making. However, this requires a scalable system for constant streaming processing, also provided with the ability of decision-making and action taking based on the performed predictions. This paper aims at proposing a scalable architecture to provide real-time context-aware actions based on predictive streaming processing of data as an evolution of a previously provided event-driven service-oriented architecture which already permitted the context-aware detection and notification of relevant data. For this purpose, we have defined and implemented a microservice-based architecture which provides real-time context-aware actions based on predictive streaming processing of data. As a result, our architecture has been enhanced twofold: on the one hand, the architecture has been supplied with reliable predictions through the use of predictive analytics and complex event processing techniques, which permit the notification of relevant context-aware information ahead of time. On the other, it has been refactored towards a microservice architecture pattern, highly improving its maintenance and evolution. The architecture performance has been evaluated with an air quality case study

    ¿Qué hay detrás del miedo a los exámenes?

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    Introducción: Se analizan las características psicológicas de una muestra de 32 estudiantes de medicina que solicitan ayuda para afrontar el miedo a los exámenes. Material y método: Las pruebas seleccionadas para el análisis de esta población son el GHQ-28, el STAI de rasgo, la escala de percepción de estrés del UNCAHS y la Sensibilidad al Castigo y a la Recompensa (SCRS). Los puntajes obtenidos se compararon con los de un grupo control de estudiantes de primer curso. Resultados: 90 % de los sujetos de la muestra fueron mujeres y el 2 5 % recibieron o estaban recibiendo atención psicológica o psiquiátrica. Entre los estudiantes que solicitaron ayuda había un nivel más alto de psicopatología, una más alta sensibilidad al castigo y una más baja sensibilidad a la recompensa que en el grupo control. Conclusiones: Los estudiantes con ansiedad ante los exámenes presentan más sensibilidad al castigo y menos sensibilidad a la recompensa, y muestran más síntomas depresivos y obsesivos que los estudiantes del grupo control

    Giant vortex state in perforated aluminum microsquares

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    We investigate the nucleation of superconductivity in a uniform perpendicular magnetic field H in aluminum microsquares containing a few (2 and 4) submicron holes (antidots). The normal/superconducting phase boundary T_c(H) of these structures shows a quite different behavior in low and high fields. In the low magnetic field regime fluxoid quantization around each antidot leads to oscillations in T_c(H), expected from the specific sample geometry, and reminiscent of the network behavior. In high magnetic fields, the T_c(H) boundaries of the perforated and a reference non-perforated microsquare reveal cusps at the same values of Phi/Phi_0 (where Phi is the applied flux threading the total square area and Phi_0 is the superconducting flux quantum), while the background on T_c(H) becomes quasi-linear, indicating that a giant vortex state is established. The influence of the actual geometries on T_c(H) is analyzed in the framework of the linearized Ginzburg-Landau theory.Comment: 14 pages, 6 PS figures, RevTex, accepted for publication in Phys. Rev.

    Cord serum cotinine as a biomarker of fetal exposure to cigarette smoke at the end of pregnancy.

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    This study investigated the association between biomarkers of fetal exposure to cigarette smoke at the end of pregnancy, cotinine in cord serum and in maternal and newborn urine samples, and quantitative measurement of smoking intake and exposure evaluated by maternal self-reported questionnaire. Study subjects were 429 mothers and their newborns from a hospital in Barcelona, Spain. A questionnaire including smoking habits was completed in the third trimester of pregnancy and on the day of delivery. Cotinine concentration in cord serum was associated with daily exposure to nicotine in nonsmokers and with daily nicotine intake in smokers. The geometric mean of cotinine concentration in cord serum statistically discriminated between newborns from nonexposed and exposed nonsmoking mothers, and between these two classes and smokers, and furthermore was able to differentiate levels of exposure to tobacco smoke and levels of intake stratified in tertiles. Urinary cotinine levels in newborns from nonsmoking mothers exposed to more than 4 mg nicotine daily were statistically different from levels in two other categories of exposure. Cotinine concentration in urine from newborns and from mothers did not differentiate between exposure and nonexposure to environmental tobacco smoke (ETS) in nonsmoking mothers. Cord serum cotinine appeared to be the most adequate biomarker of fetal exposure to smoking at the end of pregnancy, distinguishing not only active smoking from passive smoking, but also exposure to ETS from nonexposure

    Biology and ecology of the non-indigenous goby Acentrogobius pflaumii (Bleeker 1853) in the Swan-Canning Estuary

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    Non-indigenous species can have significant deleterious impacts on the ecosystems in which they become established. Following the recent establishment of the Striped Sandgoby Acentrogobius pflaumii in the Swan-Canning Estuary, south-western Australia, a study was initiated to determine its spatial and temporal distribution and biological characteristics. Although A. pflaumii was not recorded in the coarse sandy sediment present in the nearshore, shallow waters of the estuary, substantial numbers were recorded on soft muddy sediments in the deeper waters, where it comprised 55% of the total number of gobies. While A. pflaumii dominated the gobiid fauna in Lower Melville Water (~98%), its contributions declined progressively upstream, indicating a preference for waters with a salinity close to that of full strength sea water. Size and age compositions determined that the oldest individual was 3.9 years old and 89 mm in total length, but that the population is dominanted by 1+ individuals. Population mortality and turn-over rates are therefore likely to be very high. Both males and females attained > 87% of their asymptotic lengths (L∞) of 74.9 and 69.3 mm, respectively, during the first year of life, which is characteristic of smaller, shorter-lived species of fish. The results from gonadosomatic indices and the histological examination of gonads suggest that A. pflaumii is able to spawn throughout most of the year, with a peak from November to February. The presence of mature, spawning and depleted gonads in A. pflaumii suggests that this species spawns within the Swan-Canning Estuary. Acentrogobius pflaumii can be thus considered an estuarine & marine species like Favonigobius lateralis. As A. pflaumii attains high densities over a relatively large part of the estuary and can breed within the system, it is likely to be a permanent resident and further work is needed to determine its impact on the native gobiid fauna
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