7,122 research outputs found

    Probabilistic prediction of raw and BMA calibrated AEMET-SREPS: the 24 of January 2009 extreme wind event in Catalunya

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    At 00:00 UTC of 24 January 2009 (24Jan09) an explosive cyclogenesis placed at the Gulf of Vizcaya, reached its maximum intensity with observed surface pressures below 970 hPa on its center. During its path through the south of France there were strong westerly and north-westerly winds over Iberian Peninsula (above 150 km/h). These extreme winds leaved 8 casualties in Catalunya, the north-east region of Spain. <br><br> The aim of this work is validating the skill of the Spanish Meteorological Agency (AEMET) Short Range Ensemble Prediction System (SREPS) in forecasting this event. Two probabilistic forecasts of wind are compared, a non-calibrated (or raw) and a calibrated one using the Bayesian Model Averaging (BMA). <br><br> AEMET runs a daily experimental SREPS twice a day (00:00 and 12:00 UTC). This system consists on 25 members that are constructed by integrating five different Limited Area Models (LAMs) at 0.25 degrees of horizontal resolution. Each model uses five different initial and boundary conditions from five Global Models (GMs). Thus it is obtained a probabilistic forecast that takes into account initial, contour and model uncertainties. <br><br> BMA is a statistical tool for combining predictive Probability Distribution Functions (PDFs) from different sources. BMA predictive PDF is a weighted average of PDFs centered on the individual bias-corrected forecasts. Each weight is a measure of the corresponding forecast skill. Here BMA is applied to calibrate probabilistic forecasts of wind speed. <br><br> In this work two time forecast ranges (H+60 and H+36) of 10-m wind speed over Catalonia are verified subjectively at 12:00 UTC of 24Jan09 valid time. We focus on the location and intensity of 10-m wind speed maximum values. Observations at 29 automatic ground stations of AEMET are used for the verification. <br><br> On one hand results indicate that raw AEMET-SREPS is able to forecast 60 h ahead mean winds higher than 36 and 54 km/h and that it correctly locates them in three different areas. On the other hand, predicted probability loses its skill after BMA calibration of the ensemble. This is due to the fact that BMA bias correction underestimates the intensity of wind

    Tunneling mechanism of light transmission through metallic films

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    A mechanism of light transmission through metallic films is proposed, assisted by tunnelling between resonating buried dielectric inclusions. This is illustrated by arrays of Si spheres embedded in Ag. Strong transmission peaks are observed near the Mie resonances of the spheres. The interaction among various planes of spheres and interference effects between these resonances and the surface plasmons of Ag lead to mixing and splitting of the resonances. Transmission is proved to be limited only by absorption. For small spheres, the effective dielectric constant can be tuned to values close to unity and a method is proposed to turn the resulting materials invisible.Comment: 4 papges, 5 figure

    Quantum Magnetic Deflagration in Mn12 Acetate

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    We report controlled ignition of magnetization reversal avalanches by surface acoustic waves in a single crystal of Mn12 acetate. Our data show that the speed of the avalanche exhibits maxima on the magnetic field at the tunneling resonances of Mn12. Combined with the evidence of magnetic deflagration in Mn12 acetate (Suzuki et al., cond-mat/0506569) this suggests a novel physical phenomenon: deflagration assisted by quantum tunneling.Comment: 4 figure

    Injectable hydrogels based on pluronic/water systems filled with alginate microparticles: Rheological characterization

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    In this paper the rheological characterization of Pluronic/water systems filled with alginate microparticles is presented. The rheological characterization of the Pluronic/water systems allowed for the choice of the best Pluronic concentration taking into account its applications as injectable hydrogels for tissue repair. The effect on the rheological behavior of the addition of alginate microparticles, to be loaded with the drug, was analyzed and the maximum concentration of microparticles determined.Spanish Ministerio de Economia y CompetitividadV Plan Propio Universidad de SevillaEuropean Union (EU)Portuguese Foundation for Science and Technology 288 UID/CTM/50025/201

    Climatic vulnerabilities and ecological preferences of soil invertebrates across biomes.

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    Unlike plants and vertebrates, the ecological preferences, and potential vulnerabilities of soil invertebrates to environmental change, remain poorly understood in terrestrial ecosystems globally. We conducted a cross-biome survey including 83 locations across six continents to advance our understanding of the ecological preferences and vulnerabilities of the diversity of dominant and functionally important soil invertebrate taxa, including nematodes, arachnids and rotifers. The diversity of invertebrates was analyzed through amplicon sequencing. Vegetation and climate drove the diversity and dominant taxa of soil invertebrates. Our results suggest that declines in forest cover and plant diversity, and reductions in plant production associated with increases in aridity, can result in reductions of the diversity of soil invertebrates in a drier and more managed world. We further developed global atlases of the diversity of these important soil invertebrates, which were cross-validated using an independent database. Our study advances the current knowledge of the ecological preferences and vulnerabilities of the diversity and presence of functionally important soil invertebrates in soils from across the globe. This information is fundamental for improving and prioritizing conservation efforts of soil genetic resources and management policies

    Real world preventative drug management of migraine among Spanish neurologists

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    BACKGROUND: Many different preventatives have showed efficacy in the treatment of migraine. National guidelines differ in their recommendations and patients' characteristics are usually taken into account in their selection. In Spain, real life use of preventive therapies seems to be heterogeneous. We aimed to evaluate differences in clinical practice and adherence to national guidelines among Spanish neurologists. METHODS: Observational descriptive study. A survey was conducted among neurologists ascribed to the Spanish Society of Neurology. Participants were differentiated in accordance with their dedication to headache disorders. We analysed socio-demographic parameters and evaluated 43 questions considering migraine management as well as therapeutic choices regarding migraine sub-types and finally, neurologists' personal perception. RESULTS: One hundred fifty-five neurologists participated from 17 different regions, 43.4% of them female and 53.3% under 40Âżyears of age. 34.9% confirmed headache disorders as their main interest. The first choice for preventive therapy in chronic migraine among participants was topiramate (57%) followed by amytriptiline (17.9%) and beta-blockers (14.6%). However in episodic migraine, the preferred options were beta-blockers (47.7%), topiramate (21.5%) and amytriptiline (13.4%). Regarding perceived efficacy, topiramate was considered the best option in chronic migraine (42.7%) followed by onabotulinumtoxinA (25.5%) and amitryptiline (22.4%). Where episodic migraine was concerned, surveyed neurologists perceived topiramate (43.7%) and beta-blockers (30.3%) as the best options. When we evaluated the duration of treatment use with a view to adequate therapeutic response, 43.5% of neurologists preferred 3Âżmonths duration and 39.5% were in favour of 6Âżmonths duration in episodic migraine. However, considering the preferred duration of treatment use in chronic migraine, 20.4% recommended 3Âżmonths, 42.1% preferred 6Âżmonths and 12.5% and 22.4% opted for 9 and 12Âżmonths respectively. When considering onabotulinumtoxinA therapy, the number of prior therapeutic failures was zero in 7.2% of neurologists, one in 5.9%, two in 44.1%, three in 30.9% and four or more in 11.9%. Following an initial treatment failure with onabotulinumtoxinA, 49% of subjects decided against a second treatment. The number of OnabotA procedures before considering it as ineffective was two in 18.9% of neurologists, three in 70.8% and four in 10.4%. CONCLUSIONS: The initial management of migraine among Spanish Neurologists is in line with most guidelines, where first choice preventative drugs are concerned. The Management of episodic migraine differed from chronic migraine, both in terms of neurologist preference and in their perceived efficacy

    The action of obestatin in skeletal muscle repair: stem cell expansion, muscle growth, and microenvironment remodeling

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    The development of therapeutic strategies for skeletal muscle diseases, such as physical injuries and myopathies, depends on the knowledge of regulatory signals that control the myogenic process. The obestatin/GPR39 system operates as an autocrine signal in the regulation of skeletal myogenesis. Using a mouse model of skeletal muscle regeneration after injury and several cellular strategies, we explored the potential use of obestatin as a therapeutic agent for the treatment of trauma-induced muscle injuries. Our results evidenced that the overexpression of the preproghrelin, and thus obestatin, and GPR39 in skeletal muscle increased regeneration after muscle injury. More importantly, the intramuscular injection of obestatin significantly enhanced muscle regeneration by simulating satellite stem cell expansion as well as myofiber hypertrophy through a kinase hierarchy. Added to the myogenic action, the obestatin administration resulted in an increased expression of VEGF/VEGFR2 and the consequent microvascularization, with no effect on collagen deposition in skeletal muscle. Furthermore, the potential inhibition of myostatin during obestatin treatment might contribute to its myogenic action improving muscle growth and regeneration. Taken together, our data demonstrate successful improvement of muscle regeneration, indicating obestatin is a potential therapeutic agent for skeletal muscle injury and would benefit other myopathies related to muscle regeneration

    MRQAR: A generic MapReduce framework to discover quantitative association rules in big data problems

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    Many algorithms have emerged to address the discovery of quantitative association rules from datasets in the last years. However, this task is becoming a challenge because the processing power of most existing techniques is not enough to handle the large amount of data generated nowadays. These vast amounts of data are known as Big Data. A number of previous studies have been focused on mining boolean or nominal association rules from Big Data problems, nevertheless, the data in real-world applications usually consist of quantitative values and designing data mining algorithms able to extract quantitative association rules presents a challenge to workers in this research field. In spite of the fact that we can find classical methods to discover boolean or nominal association rules in the most well-known repositories of Big Data algorithms, such repositories do not provide methods to discover quantitative association rules. Indeed, no methodologies have been proposed in the literature without prior discretization in Big Data. Hence, this work proposes MRQAR, a new generic parallel framework to discover quantitative association rules in large amounts of data, designed following the MapReduce paradigm using Apache Spark. MRQAR performs an incremental learning able to run any sequential quantitative association rule algorithm in Big Data problems without needing to redesign such algorithms. As a case study, we have integrated the multiobjective evolutionary algorithm MOPNAR into MRQAR to validate the generic MapReduce framework proposed in this work. The results obtained in the experimental study performed on five Big Data problems prove the capability of MRQAR to obtain reduced set of high quality rules in reasonable time.Ministerio de EconomĂ­a y Competitividad TIN2017-89517-PMinisterio de EconomĂ­a y Competitividad TIN2014-55894-C2-1-RMinisterio de EconomĂ­a y Competitividad TIN2017-88209-C2-2-

    Inflationary models inducing non-Gaussian metric fluctuations

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    We construct explicit models of multi-field inflation in which the primordial metric fluctuations do not necessarily obey Gaussian statistics. These models are realizations of mechanisms in which non-Gaussianity is first generated by a light scalar field and then transferred into curvature fluctuations. The probability distribution functions of the metric perturbation at the end of inflation are computed. This provides a guideline for designing strategies to search for non-Gaussian signals in future CMB and large scale structure surveys.Comment: 4 pages, 7 figure
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