556 research outputs found

    Shot Noise in Linear Macroscopic Resistors

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    We report on a direct experimental evidence of shot noise in a linear macroscopic resistor. The origin of the shot noise comes from the fluctuation of the total number of charge carriers inside the resistor associated with their diffusive motion under the condition that the dielectric relaxation time becomes longer than the dynamic transit time. Present results show that neither potential barriers nor the absence of inelastic scattering are necessary to observe shot noise in electronic devices.Comment: 10 pages, 5 figure

    RGS10 shapes the hemostatic response to injury through its differential effects on intracellular signaling by platelet agonists.

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    Platelets express ≥2 members of the regulators of G protein signaling (RGS) family. Here, we have focused on the most abundant, RGS10, examining its impact on the hemostatic response in vivo and the mechanisms involved. We have previously shown that the hemostatic thrombi formed in response to penetrating injuries consist of a core of fully activated densely packed platelets overlaid by a shell of less-activated platelets responding to adenosine 5\u27-diphosphate (ADP) and thromboxane A2 (TxA2). Hemostatic thrombi formed in RGS10-/- mice were larger than in controls, with the increase due to expansion of the shell but not the core. Clot retraction was slower, and average packing density was reduced. Deleting RGS10 had agonist-specific effects on signaling. There was a leftward shift in the dose/response curve for the thrombin receptor (PAR4) agonist peptide AYPGKF but no increase in the maximum response. This contrasted with ADP and TxA2, both of which evoked considerably greater maximum responses in RGS10-/- platelets with enhanced Gq- and Gi-mediated signaling. Shape change, which is G13-mediated, was unaffected. Finally, we found that free RGS10 levels in platelets are actively regulated. In resting platelets, RGS10 was bound to 2 scaffold proteins: spinophilin and 14-3-3γ. Platelet activation caused an increase in free RGS10, as did the endothelium-derived platelet antagonist prostacyclin. Collectively, these observations show that RGS10 serves as an actively regulated node on the platelet signaling network, helping to produce smaller and more densely packed hemostatic thrombi with a greater proportion of fully activated platelets

    Geomorphological evolution of the western piedmont of Cumbres Calchaquíes (Tucumán Province, NW Argentina)

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    The aim of this paper is to present a detailed geomorphological map of the western piedmont of Cumbres Calchaquíes (Tucumán Province, NW Argentina) bounded by the Amaicha River to the south and the administrative border with Salta Province to the north. It contains information about geomorphological units, their relative ages, and morphogenetic processes. The main map shows the presence of seven aggradation stages separated by incision phases. The first three stages (St1, St2, and St3) were modeled on a thick accumulation located in the upper piedmont from the Late Pliocene and Early Pleistocene. Intermediate stages (St4 and St5) are alluvial fans and pediments with less thickness and gradient. They cover the Early Pleistocene (St4) and the Late Pleistocene-Middle Holocene (St5). Finally, stages St6 and St7 are from the Upper Holocene

    Riesgos geomorfológicos pasados y presentes y pérdidas de patrimonio cultural en el escarpe del castillo de El Castellar (Cuenca Central del Ebro, España)

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    The ruins of the Medieval castle and village of El Castellar are located on an abrupt 1.2-km-long scarp of Miocene gypsums, in the central sector of the Ebro depression. The Medieval remains of the main El Castellar castle are perched on a 100 m cliff on the Ebro River. Considering the historical and geoarchaeological relevance of El Castellar settlement, this investigation aimed to study the geomorphological hazards and paleoenvironmental context of the site during and after the settlement and its later evolution, including its current state. To afford this objective the geomorphological context was determined analyzing the dynamics of each scarp sector. Geomorphological data suggest that in Medieval times its constructions were favored by the Medieval Climatic Anomaly (MCA) environmental conditions. During that times, the Ebro River was located in a centered position on its floodplain, and lateral alluvial fans protected the scarp from basal erosion. Later, during the Little Ice Age (LIA), great climatic flows and recurrent floods changed the river dynamics and promoted the river channel movement against the scarp, destabilizing its foot and generating large landslides and rockfalls, thus promoting its retreat. The village buildings and castle at the top of the scarp were seriously damaged. For several reasons, the area is not easily accessible, but it still contains a relevant archaeological heritage that deserves to be studied and preserved.Las ruinas del castillo medieval y villa de El Castellar se sitúan sobre un abrupto escarpe de yesos del Mioceno de 1,2 km de longitud, en el sector central de la Depresión del Ebro. Los restos medievales del castillo principal de El Castellar se alzan sobre un acantilado de 100 m sobre el río Ebro. Teniendo en cuenta la relevancia histórica y geoarqueológica del poblamiento de El Castellar, esta investigación tiene como objetivo estudiar los peligros geomorfológicos y el contexto paleoambiental del yacimiento durante y después del poblamiento y su evolución posterior, incluyendo su estado actual. Para lograr este objetivo se determinó el contexto geomorfológico analizando la dinámica de cada sector del escarpe. Los datos geomorfológicos sugieren que en época medieval sus construcciones se vieron favorecidas por las condiciones ambientales de la Anomalía Climática Medieval (ACM). En esa época, el río Ebro estaba situado en una posición centrada en su llanura de inundación, y los abanicos aluviales laterales protegían el escarpe de la erosión basal. Posteriormente, durante la Pequeña Edad del Hielo (LIA), grandes caudales y recurrentes inundaciones cambiaron la dinámica del río y promovieron el movimiento del cauce contra el escarpe, desestabilizando su pie y generando grandes derrumbes y desprendimientos, favoreciendo así su retroceso. Los edificios del pueblo y el castillo en la parte superior de la escarpa sufrieron graves daños. Por varias razones, la zona no es de fácil acceso, pero aún contiene un importante patrimonio arqueológico que merece ser estudiado y preservado.Fil: Peña Monné, José Luis. Universidad de Zaragoza. Facultad de Filosofía y Letras; EspañaFil: Sampietro Vattuone, Maria Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Laboratorio de Geoarqueología; ArgentinaFil: Espinalt Brillas, Marta. Oficina eSalut; EspañaFil: Gutiérrez González, Francisco J.. Universidad de Zaragoza. Facultad de Filosofía y Letras; Españ

    Readmissions and the quality of care in patients hospitalized with heart failure

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    Objectives. Clinical practice guidelines based on the results of randomized clinical trials recommend that patients with heart failure due to left ventricular systolic dysfunction (LVSD) be treated with angiotensin-converting enzyme inhibitors (ACEI) at doses shown to reduce mortality and readmission. This study examined the relationship between ACEI use at discharge and readmission among patients with heart failure due to LVSD. Methods and results. Data were abstracted from the medical records of 2943 randomly selected patients hospitalized for heart failure in 50 hospitals. The outcome of interest was the number of readmissions occurring up to 21 months after discharge. Six-hundred and eleven patients were eligible for analysis. Compared with patients discharged at a recommended ACEI dose, patients not prescribed an ACEI at discharge had an adjusted rate ratio of readmission (RR) of 1.74 [95% confidence interval (CI) 1.22-2.48], while patients prescribed an ACEI at less than a recommended dose had an RR of 1.24 (95% CI 0.91-1.69) (P = 0.005 for the trend). Conclusion. Our results show that ACEI use at discharge in patients with LVSD is associated with decreased rate of readmission. These findings suggest that compliance with the ACEI prescribing recommendations listed in clinical practice guidelines for patients with heart failure due to LVSD confers benefi

    Fiber-to-waveguide alignment assisted by a transparent integrated light monitor

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    A novel fiber-to-waveguide alignment technique assisted by a transparent integrated light monitor is presented. The waveguide power is measured near the chip input facet by the contactless integrated photonic probe, which provides a feedback electrical signal steering the fiber positioning system. Automated single fiber to silicon nanowaveguide coupling is demonstrated with 40-nm resolution in a time scale of few seconds. The presented approach makes the fiber alignment procedure independent of the optical circuit integrated on the photonic chip, avoiding the need for simultaneous alignment of an output fiber, and thus easing optical chip characterization, wafer-level testing, and packaging of photonic devices
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