216 research outputs found
Predictability of the monthly North Atlantic Oscillation index based on fractal analyses and dynamic system theory
The predictability of the monthly North Atlantic Oscillation, NAO, index is analysed from the point of view of different fractal concepts and dynamic system theory such as lacunarity, rescaled analysis (Hurst exponent) and reconstruction theorem (embedding and correlation dimensions, Kolmogorov entropy and Lyapunov exponents). The main results point out evident signs of randomness and the necessity of stochastic models to represent time evolution of the NAO index. The results also show that the monthly NAO index behaves as a white-noise Gaussian process. The high minimum number of nonlinear equations needed to describe the physical process governing the NAO index fluctuations is evidence of its complexity. A notable predictive instability is indicated by the positive Lyapunov exponents. Besides corroborating the complex time behaviour of the NAO index, present results suggest that random Cantor sets would be an interesting tool to model lacunarity and time evolution of the NAO index
Lacunarity, predictability and predictive instability of the daily pluviometric regime in the Iberian Peninsula
The complexity of the daily pluviometric regime of the Iberian Peninsula is analysed from the point of view of its lacunarity, predictability and predictive instability. The database consists of daily pluviometric records obtained from 43 rain gauges in Spain and Portugal for the period 1950–1990. Five different series are generated for every rain gauge. The first series is constituted by the consecutive daily amounts. The other four consist of dry spell lengths with respect to daily amount thresholds of 0.1, 1.0, 5.0 and 10.0 mm/day. A dry spell length is defined as the number of consecutive days with rainfall amounts below one of these thresholds. The empirical lacunarity for every rain gauge is well reproduced by two power laws, the exponents varying notably from one gauge to another. The spatial distribution of the lacunarity is characterised by a north to south or southeast gradient, thus suggesting that this parameter can be a useful tool to distinguish between different pluviometric regimes. The predictability of the five series is quantified by means of the rescaled analysis and the interpretation of the Hurst exponent. Its patterns reveal that most part of the Iberian Peninsula shows signs of persistence for the daily rainfall and the dry spell series, although persistence is only clearly manifested in some small domains. The instability of possible predictive algorithms is analysed through the Lyapunov exponents. They are only computed for the series of daily amounts and for dry lengths respect to the threshold level of 0.1 mm/day due to the short number of dry spells for larger threshold levels. The series of daily amounts depict the highest instability along the Mediterranean coast. The series of dry spells show an increasing instability from NE to SW Spain, with a relevant nucleus of high Lyapunov values in the south-western Atlantic coast. As a summary, lacunarity and Hurst and Lyapunov exponents depict a relevant spatial variation, which is in agreement with well known patterns of the pluviometric regime, such as annual amount spatial distribution and return periods of dry spells
Palatability of Alfalfa (\u3cem\u3eMedicago sativa\u3c/em\u3e L.) and Orchard Grass (\u3cem\u3eDactylis glomerata\u3c/em\u3e L.) Silages
The objective was to compare palatability with different methodologies for characterizing silages at Chapingo Autonomous University, México. Eight silages were used resulting from an experiment which evaluated effects of cutting time (08:00 and 14:00), time of wilting (0, 1 and 2 h) and use of lactic bacteria inoculant on properties of alfalfa (Medicago sativa L.) and orchard grass (Dactylis glomerata L.) silages. Organoleptic properties (odor, color, texture, moisture) were assessed by trained observers, using as categories: excellent, good, fair and poor. Dry matter content, CO2 rate of production and pH were also measured. For the evaluation of palatability with ewes, the experiment encompassed 18 days of adaptation and 14 days of measurement. In each of the 14 days of evaluation, four combinations of silages were evaluated (three silages per combination), each one assigned to experimental units formed by three ewes allotted by means of ratified random; each experimental unit was housed during 2.5 h in a pen with three feeders. The silages to be evaluated daily by each experimental unit were allotted randomly to these feeders. Silages harvested at 14:00 achieved highest scores in organoleptic, preference and intake evaluations. Results of preference and intake were similar and the results of PCA ordering of treatments resembled those of odor and texture and were opposite to those of pH and in a lesser extent also to those of aerobic deterioration. The organoleptic evaluation resulted an easy and cheap method to characterize silages, which results were reliable predictors of preference and intake (and hence quality) of alfalfa and orchard grass silages
Generalidades de la familia Filoviridae y el virus del Ébola: una actualización de sus implicaciones en la población humana
Characteristics of the family Filoviridae and the Ebola virus: an update of its implications in the human population The family Filoviridae is integrated by a group of filamentous RNA viruses that cause severe hemorrhagic fevers in primates and other mammals, including humans, mainly in the African continent. Ebolavirus, arburgrvirus and Lloviu cuevavirus are the members of this family, and their main reservoirs are bats from the family Pteropodidae. The present review describes the main characteristics of the Filoviruses, pathophysiology and epidemiology on the human population, with a focus on the Ebolavirus, a pathogen of great epidemiological importance responsible for the death of 13 293 people since 1976. The Ebola outbreak of 2014-2016 was the largest in history, with 28 652 cases, representing more than 90% of the total number of cases reported since the origin of the disease (31 685). The transmission of the virus between humans can happen directly, through ontaminated fluids, or indirectly, by parenteral transmission and fomites. The incubation period ranges from 2 to 21 days and the symptomatology is divided in four phases: a febrile phase with nonspecific symptoms, a phase characterized by gastrointestinal symptoms, and two with the presence of critical symptoms. Although there is no specific treatment for the Ebola virus disease, the development of potential vaccines is currently underway, and some have showed positive results in animal models. This could lead to the appearance of an effective treatment that increases the survival of infected patients, and better epidemiological control
Activation of nucleus accumbens NMDA receptors differentially affects appetitive or aversive taste learning and memory
Taste memory depends on motivational and post-ingestional consequences; thus, it can be aversive (e.g., conditioned taste aversion, CTA) if a novel, palatable taste is paired with visceral malaise, or it can be appetitive if no intoxication appears after novel taste consumption, and a taste preference is developed.The nucleus accumbens (NAc) plays a role in hedonic reactivity to taste stimuli, and recent findings suggest that reward and aversion are differentially encoded by the activity of NAc neurons. The present study examined whether the requirement for N-methyl-D-aspartate (NMDA) receptors in the NAc core during rewarding appetitive taste learning differs from that during aversive taste conditioning, as well as during retrieval of appetitive vs. aversive taste memory, using the taste preference or CTA model, respectively. Bilateral infusions of NMDA (1 μg/μl, 0.5 μl) into the NAc core were performed before acquisition or before retrieval of taste preference or CTA. Activation of NMDA receptors before taste preference training or CTA acquisition did not alter memory formation. Furthermore, NMDA injections before aversive taste retrieval had no effect on taste memory; however, 24 h later, CTA extinction was significantly delayed. Also, NMDA injections, made before familiar appetitive memory retrieval, interrupted the development of taste preference and produced a preference delay 24 h later. These results suggest that memory formation for a novel taste produces neurochemical changes in the NAc core that have differential requirements for NMDA receptors during retrieval of appetitive or aversive memory
Ensiling Alfalfa (Medicago sativa L.) and Orchard Grass (Dactylis glomerata L.) Forage Harvested at 08:00 or 14:00, without Wilting or 1 or 2 h Wilting and with or without Use of Bacterial Inoculant
Alfalfa forage is difficult to ensile due to low water-soluble carbohydrate content and high buffering capacity. The objective was to assess at Chapingo, Mexico, during the rainy season effects of combinations of harvest hours (08:00, 14:00), wilting time (0, 1, 2 h) and bacterial inoculants on the quality of silage made of alfalfa and orchard grass forage, made in 200-L containers. The experiment was conducted in three phases with two replicates per phase. Variables measured in freshly cut forage and silages were dry matter content (DM), buffer capacity, pH, and alcohol soluble carbohydrates (ASC). Silos remained sealed during 60 d, and additional variables measured in silage were aerobic stability, NH3 -N and in vitro disappearance of DM. In forage harvested at 14:00 h, DM and ASC contents were higher; pH and buffering capacity were not affected by harvest hour; in silages made of that forage, NH3-N levels were lower, while ASC contents and in vitro disappearance of MS were unaffected by harvest hour. Treatments with inoculants were less aerobic stable for 5 days when made of forage harvested at 08:00 h but more stable when made of forage harvested at 14:00 h. Harvesting at 14:00 h was advantageous as silage presented higher DM and ASC contents
Fístula arteriovenosa postraumática: tratamiento endovascular. Revisión de la literatura y presentación de un caso clínico
ResumenLas fístulas arteriovenosas en la cabeza y el cuello son entidades poco frecuentes. La mayoría es secundaria a heridas penetrantes por arma blanca. Se describe el tratamiento exitoso mediante cirugía endovascular de una fístula postraumática tras una herida penetrante entre la arteria maxilar interna izquierda y la vena yugular externa. A través de este caso clínico y la revisión de la literatura se ilustran las causas, manifestaciones, estudio radiológico y tratamiento de una fístula postraumática entre la arteria maxilar interna y la vena yugular externa. A través de este caso clínico se demuestra la utilidad de los procedimientos endovasculares en el tratamiento de estas complicaciones.AbstractTraumatic arteriovenous fistulas of the head and neck region are uncommon. The majority are due to penetration of blunt injury. We describe a successful endovascular treatment of a posttraumatic fistula between the left maxillary artery and the external jugular vein due to a penetration injury. This case and a review of the literature illustrate the causes, manifestations, image studies and treatment for a posttraumatic fistula between the maxillary artery and the external jugular vein. This case demonstrate the utility of endovascular treatment of head and neck injuries complications
Issues to resolve with the use of extracorporeal membrane oxygenation during interfacility transportation.
Extracorporeal membrane oxygenation (ECMO) support is indicated for patients who are refractory to treatment, those with cardiogenic shock or respiratory failure and those with exacerbations eligible for heart and lung transplantation. The practitioner’s experience and quantity of necessary resources are reasons why regionalization could benefit these types of patients, establishing ECMO reference centers and integrating a transportation network specialized in ECMO.
This type of transportation is a challenge for healthcare systems and physicians, given its greater complexity, requiring a multidisciplinary and interterritorial approach.
ECMO transportation is safer than without mechanical support, although there are currently no criteria for starting the therapy on patients being transferred. Criteria of lesser severity might be necessary for these patients. The training and specialization of the team in extracorporeal support therapies, interfacility transport and the systemization of the transfer can improve results.
There are no studies on the conditions that must be met by the transportation media, although space and stability are important characteristics. Air transfer with ECMO is an increasingly frequent option. Although there are data on its safety, there are none on the physiology of patients undergoing ECMO at high altitudes, data that could help with the indication and management of this type of transportation.pre-print916 K
Distributed Model-to-Model Transformation with ATL on MapReduce
International audienceEfficient processing of very large models is a key requirement for the adoption of Model-Driven Engineering (MDE) in some industrial contexts. One of the central operations in MDE is rule-based model transformation (MT). It is used to specify manipulation operations over structured data coming in the form of model graphs. However, being based on com-putationally expensive operations like subgraph isomorphism, MT tools are facing issues on both memory occupancy and execution time while dealing with the increasing model size and complexity. One way to overcome these issues is to exploit the wide availability of distributed clusters in the Cloud for the distributed execution of MT. In this paper, we propose an approach to automatically distribute the execution of model transformations written in a popular MT language, ATL, on top of a well-known distributed programming model, MapReduce. We show how the execution semantics of ATL can be aligned with the MapReduce computation model. We describe the extensions to the ATL transformation engine to enable distribution, and we experimentally demonstrate the scalability of this solution in a reverse-engineering scenario
La necesidad de medir la motivación situacional en el contexto español de la educación física: Psicometría de la Situational Motivation Scale
El objetivo primario de este trabajo fue comparar la estructura factorial de las diversas versiones propuestas (SIMS-16, SIMS-15, SIMS-14 y SIMS-13), así como de explorar la posible sostenibilidad de una nueva estructura para la Situational Motivation Scale (SIMS) en el contexto español de la Educación Física. El objetivo secundario fue aportar evidencias que respalden la invariancia factorial, consistencia interna y validez externa de la mejor estructura factorial identificada. Participaron 644 estudiantes (344 hombres y 300 mujeres; Medad = 15,04, DT = 1,58) de educación secundaria obligatoria y bachillerato en clase de EF. El análisis factorial confirmatorio no respaldó psicométricamente las diferentes versiones (SIMS-16, SIMS-15, SIMS-14 y SIMS-13) identificadas por la investigación previa para la SIMS. No obstante, los hallazgos sustentaron psicométricamente un modelo factorial de cuatro factores correlacionados y 12 ítems, que permaneció invariante respecto al género y nivel educativo. El análisis correlacional apoyó la validez discriminante del instrumento y, a su vez, respaldó el continuum de auto-determinación. El análisis de consistencia interna reflejó adecuados valores para cada factor. Los resultados del modelo de ecuaciones estructurales respaldaron los asertos del Modelo Jerárquico de Motivación Intrínseca/ Extrínseca. Como conclusión, se recomienda la utilización de una nueva estructura factorial para la Situational Motivation Scale (modelo de cuatro factores correlacionados y 12 ítems) para el alumnado de EF de secundaria obligatoria y bachillerato en el contexto español
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