970 research outputs found

    Climatic niche and neutral genetic diversity of the six Iberian pine species: a retrospective and prospective view

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    Quaternary climatic fluctuations have left contrasting historical footprints on the neutral genetic diversity patterns of existing populations of different tree species. We should expect the demography, and consequently the neutral genetic structure, of taxa less tolerant to particular climatic extremes to be more sensitive to long-term climate fluctuations. We explore this hypothesis here by sampling all six pine species found in the Iberian Peninsula (2464 individuals, 105 populations), using a common set of chloroplast microsatellite markers, and by looking at the association between neutral genetic diversity and species-specific climatic requirements. We found large variation in neutral genetic diversity and structure among Iberian pines, with cold-enduring mountain species (Pinus uncinata, P. sylvestris and P. nigra) showing substantially greater diversity than thermophilous taxa (P. pinea and P. halepensis). Within species, we observed a significant positive correlation between population genetic diversity and summer precipitation for some of the mountain pines. The observed pattern is consistent with the hypotheses that: (i) more thermophilous species have been subjected to stronger demographic fluctuations in the past, as a consequence of their maladaptation to recurrent glacial cold stages; and (ii) altitudinal migrations have allowed the maintenance of large effective population sizes and genetic variation in cold-tolerant species, especially in more humid regions. In the light of these results and hypotheses, we discuss some potential genetic consequences of impending climate change

    Ni modélica ni fracasada. La transición a la democracia en España 1975-1982

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    La atención mostrada por los científicos sociales y los historiadores a los procesos de transición a la democracia iniciados en 1974 ha sido muy alta, sobre todo por parte de los primeros. Aunque hoy podemos afirmar que existe una sólida historiografía sobre el tema que combina lo singular y general permitiéndonos realizar análisis comparativos. Las transiciones a la democracia son procesos de naturaleza política donde conviven actitudes e instituciones autoritarias con otras democráticas. A lo largo de los últimos años se ha puesto de manifiesto, en el caso español, el papel protagonista de la «sociedad civil», hasta las elecciones fundacionales de junio de 1977. Ello implica que durante la etapa reformista de la transición el comportamiento de las élites políticas estuvo condicionado por la presión y opinión de la «sociedad civil»The attention shown by social scientists and historians to the transition to democracy began in 1974 and has been very high, especially by the former. Nowadays we can say that there is a strong historiography on the subject that combines particular and general views enabling comparative analysis. Transitions to democracy are political processes where authoritarian attitudes and institutions coexist with democratic ones. In the Spanish case, over the past years, we have shown the importance of the role «civil society» until the elections of June 1977. This means that during the reformist era of transition, the political elites behavior was conditioned by the pressure and opinion of the «civil society

    Linz y la historia

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    La versión del editor está disponible en la página web del Centro de Estudios Políticos y Constitucionales http://www.cepc.gob.es/publicaciones/revistas/revistaselectronicas?IDR=

    Intravenous Thrombolysis for Acute Ischemic Stroke in a High Complex Regional Hospital

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    Background: Intravenous thrombolysis (IVT) with alteplase (tissue plasminogen activator) is the standard pharmacological treatment in acute ischemic stroke (AIS), reducing disability in patients

    Ultrasound-enhanced mass transfer during single-bubble diffusive growth

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    Ultrasound is known to enhance surface bubble growth and removal in catalytic and microfluidic applications, yet the contributions of rectified diffusion and microstreaming phenomena towards mass transfer remain unclear. We quantify the effect of ultrasound on the diffusive growth of a single spherical CO2_2 bubble growing on a substrate in supersaturated water. The time dependent bubble size, shape, oscillation amplitude and microstreaming flow field are resolved. We show and explain how ultrasound can enhance the diffusive growth of surface bubbles by up to two orders of magnitude during volumetric resonance. The proximity of the wall forces the bubble to oscillate non-spherically, thereby generating vigorous streaming during resonance that results in convection-dominated growth.Comment: Accepted in Phys. Rev. Fluid

    Bridging the visual gap in VLN via semantically richer instructions

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    The Visual-and-Language Navigation (VLN) task requires understanding a textual instruction to navigate a natural indoor environment using only visual information. While this is a trivial task for most humans, it is still an open problem for AI models. In this work, we hypothesize that poor use of the visual information available is at the core of the low performance of current models. To support this hypothesis, we provide experimental evidence showing that state-of-the-art models are not severely affected when they receive just limited or even no visual data, indicating a strong overfitting to the textual instructions. To encourage a more suitable use of the visual information, we propose a new data augmentation method that fosters the inclusion of more explicit visual information in the generation of textual navigational instructions. Our main intuition is that current VLN datasets include textual instructions that are intended to inform an expert navigator, such as a human, but not a beginner visual navigational agent, such as a randomly initialized DL model. Specifically, to bridge the visual semantic gap of current VLN datasets, we take advantage of metadata available for the Matterport3D dataset that, among others, includes information about object labels that are present in the scenes. Training a state-of-the-art model with the new set of instructions increase its performance by 8% in terms of success rate on unseen environments, demonstrating the advantages of the proposed data augmentation method.Comment: Accepted in ECCV 2022. Research completed on November 21, 202

    Epidemiology and Management of Intracerebral Hemorrhage in Chile

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    Intracerebral hemorrhage (ICH) is the second cause of stroke in Chile (23% of all strokes). The Araucanía Region has double the mortality rate by stroke compared with most regions in Chile. In developing countries like Chile, it is difficult to admit patients with ICH to the intensive care unit (ICU) for general neuroprotection and an aggressive lowering of blood pressure. The aim is to report the experience in the treatment of patients with ICH in a regional public hospital in Temuco, Chile. A convenience sample of the ICH consultations made during shift # 1 in the emergency room (ER) of the Hospital Dr. Hernán Henríquez Aravena between January 2016 and December 2018 was analyzed. There were 108 consultations for ICH in the period. The average age of the patients was 66.0 years (SD = 14.1). About 56.5% of the patients were male. Regarding the etiology, 70.4% were hypertensive, 18.5% were due to amyloid angiopathy, and 11.1% were for other causes. The implementation of 24/7 neurology shifts in the ER allowed us to reduce the evaluation time and improve the management of ICH patients. On the other hand, our hospital lacks a stroke unit, so ICH patients do not receive the standard care
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