1,880 research outputs found
May the NAO index be used to forecast rain in Spain?
This paper studies the influence of the North Atlantic Oscillation (NAO) on monthly, seasonal and annual precipitation regimes in continental Spain. The data used for this study include the monthly rain series of 325 meteorological stations distributed homogeneously over the study zone, and the monthly NAO indices from 1961 to 1998. A total of 5525 rain series were employed for the analysis. Simple and multiple linear correlations were established between these variables in different combinations. The main aim was to check whether monthly, seasonal or annual precipitation data could be predicted using earlier precipitation data and the NAO index. The geographical areas where the stations have shown a statistically significant correlation have been represented on maps. The results differ depending on the correlation, but, in general, the best results have been found in the fall and winter months. Finally, a practical application of the method was carried out in the Ebro Valley and it was observed that the combination of the NAO index for spring and summer and the precipitation registered in those two seasons may be useful to forecast rain in the fall.Este trabajo estudia la influencia de la Oscilación del Atlántico Norte (NAO) en el régimen de precipitaciones mensuales, estacionales y anuales de la España Peninsular. Para ello se han utilizado los datos mensuales de precipitación de 325 estaciones pluviométricas repartidas homogéneamente y los índices mensuales del índice NAO desde 1961 a 1998; se han usado un total de 5525 series de precipitación. El estudio se ha realizado mediante correlaciones lineales simples o múltiples entre estas variables utilizando diferentes combinaciones. Se trata de ver si se podría predecir la precipitación mensual, estacional o bien anual a partir de datos previos de precipitación y del índice NAO. Se han representado espacialmente las zonas geográficas cuyos observatorios manifiestan una correlación estadísticamente significativa. Los resultados difieren del tipo de correlación elegido, pero en general los mejores resultados se encuentran en los meses de invierno. Por último, se ha aplicado esta metodología al Valle del Ebro y se ha observado que una combinación del índice NAO de primavera y verano, junto con la precipitación registrada en esas dos estaciones podría ser útil para predecir la precipitación de otoño.publishe
Short-term study of effects of fertilisation and cutting treatments on the vegetation dynamics of mountain heathlands in Spain
P. 181-191La influencia de la gestión y la disponibilidad de nutrientes en la dinámica de la vegetación de páramos caracterizados por Calluna vulgaris y Erica tetralix fueron estudiados en tres sitios de la montaña en el norte de España. En un total de 90 parcelas (1 m2 cada uno) recibieron diferentes combinaciones de corte y dos veces el fondo deposición atmosférica estimada de nitrógeno (56 kg yr_1 ha_1). Una de las dos especies dominantes ericáceas fueron cortados selectivamente a mano a nivel del suelo y su regeneración comparan en la presencia o ausencia de la otra. Los resultados después de 2 años mostraron efectos significativos del fertilizante en la cubierta vegetal, principalmente favoreciendo especies herbáceas perennes. No hubo efectos menos notables en el número de flores y sobre el crecimiento anual de las especies de ericáceas. Se concluye que, en el corto plazo, los nutrientes aumentaron solo, al doble de la deposición atmosférica corriente estimado para la zona, no va a alterar significativamente la composición de los brezales de montaña. Sin embargo, una vez que las gradas llegan a la fase de madurez, la capacidad de la comunidad para regenerar después disminuye una perturbación grave. Un impacto drástico, como el corte no puede dar lugar a la re-crecimiento de las mismas especies de arbustos, sino en sustitución por especies herbáceas, que también se beneficiarán de la mayoría de los nutrientesS
3D 360° surface morphometric analysis of pounding stone tools used by Hadza foragers of Tanzania: A new methodological approach for studying percussive stone artefacts
Surface morphometry comprises a relevant set of techniques that provide objective tools to identify, map, and understand use wear patterns in stone tools. Thus far, these techniques have been applied mainly to 2D or 2.5D data, but their application to 3D 360° data is promising and still underdeveloped. Here, we apply new 3D techniques to calculate morphometric variables and to analyse surficial features and changes in pounding stone tools used for baobab processing among Hadza foragers of Tanzania. Baobab pounding stones were collected after use by Hadza foragers for processing the plant food and then 3D point clouds were acquired from laser scanners and SfM photogrammetry. Morphometry was conducted directly on 3D point clouds to avoid time-consuming and surface modifications related to more complex 3D data, such as meshing. Several morphometric variables were computed for the complete pieces (360° sphere) providing fast and accurate data to identify the detailed morphometric features of the artefacts. Additionally, stone surface changes due to baobab processing were measured by comparing the stone surface before and after use, thus enabling calculation of spatial abrasion patterns. Data were interpreted using multivariate exploratory statistical analysis. Differences in the effect of processing on surface morphology are likely explained by variations in raw source material and use. Results suggest that the traces produced by baobab processing on stone tools should be detectable in the archaeological record
Relationship between casting modulus and grain size in cast A356 aluminium alloys
Microstructure of Al-Si alloy castings depends most generally on melt preparation and on the cooling rate imposed by the thermal modulus of the component. In the case of Al-Si alloys, emphasis is put during melt preparation on refinement of pro-eutectic (Al) grains and on modification of the Al-Si eutectic. Thermal analysis has been used since long to check melt preparation before casting, i.e. by analysis of the cooling curve during solidification of a sample cast in an instrumented cup. The conclusions drawn from such analysis are however valid for the particular cooling conditions of the cups. It thus appeared of interest to investigate how these conclusions could extrapolate to predict microstructure in complicated cast parts showing local changes in the solidification conditions. For that purpose, thermal analysis cups and instrumented sand and die castings with different thermal moduli and thus cooling rates have been made, and the whole set of cooling curves thus recorded has been analysed. A statistical analysis of the characteristic features of the cooling curves related to grain refinement in sand and die castings allowed determining the most significant parameters and expressing the cube of grain size as a polynomial of these parameters. After introduction of a further parameter quantifying melt refining an excellent correlation, with a R2 factor of 0.99 was obtained
Error in the sampling area of an optical disdrometer: consequences in computing rain variables
The aim of this study is to improve the estimation of the characteristic uncertainties of optic disdrometers in an attempt to calculate the efficient sampling area according to the size of the drop and to study how this influences the computation of other parameters, taking into account that the real sampling area is always smaller than the nominal area. For large raindrops (a little over 6 mm), the effective sampling area may be half the area indicated by the manufacturer. The error committed in the sampling area is propagated to all the variables depending on this surface, such as the rain intensity and the reflectivity factor. Both variables tend to underestimate the real value if the sampling area is not corrected. For example, the rainfall intensity errors may be up to 50% for large drops, those slightly larger than 6 mm. The same occurs with reflectivity values, which may be up to twice the reflectivity calculated using the uncorrected constant sampling area. The Z-R relationships appear to have little dependence on the sampling area, because both variables depend on it the same way. These results were obtained by studying one particular rain event that occurred on April 16, 2006.The authors would like to thank Dr. Noelia Ramón for translating this paper into English. Ana I. Calvo acknowledges Posdoc Grant SFRH/BPD/64810/2009 from the Portuguese Science Foundation (FCT). This study was supported by the Spanish Ministry of Science and Innovation (Grant TEC2010-19241-C02-01).publishe
The role of selenium mineral trace element in exercise: antioxidant defense system, muscle performance, hormone response, and athletic performance. A systematic review
Exercise overproduces oxygen reactive species (ROS) and eventually exceeds the body’s antioxidant capacity to neutralize them. The ROS produce damaging effects on the cell membrane and contribute to skeletal muscle damage. Selenium (Se), a natural mineral trace element, is an essential component of selenoproteins that plays an important role in antioxidant defense. The activity of the enzyme glutathione peroxidase (GPx), a highly-efficient antioxidant enzyme, is closely dependent on the presence of Se. These properties of Se may be potentially applicable to improve athletic performance and training recovery. We systematically searched for published studies to evaluate the effectiveness of Se supplementation on antioxidant defense system, muscle performance, hormone response, and athletic performance among physically active individuals. We used the Preferred Reporting Elements for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and searched in SCOPUS, Web of Science (WOS), and PubMed databases to identify published studies until March 2020. The systematic review incorporated original studies with randomized controlled crossover or parallel design in which intake of Se administered once a day was compared with the same placebo conditions. No exclusions were applied for the type of physical exercise performed, the sex, nor the age of the participants. Among 150 articles identified in the search, 6 met the criteria and were included in the systematic review. The methodological quality of the studies was evaluated using the McMaster Critical Review Form. Oral Se supplementation with 180 µg/day or 240 µg/day (selenomethionine) and 200 µg/day (Sodium Selenite), significantly decreased lipid hydroperoxide levels and increased GPx in plasma, erythrocyte, and muscle. No significant effects were observed on athletic performance, testosterone hormone levels, creatine kinase activity, and exercise training-induced adaptations on oxidative enzyme activities or on muscle fiber type myosin heavy chain expression. In addition, Se supplementation showed to have a dampening effect on the mitochondria changes in chronic and acute exercise. In summary, the use of Se supplementation has no benefits on aerobic or anaerobic athletic performance but it may prevent Se deficiencies among athletes with high-intensity and high-volume training. Optimal Se plasma levels may be important to minimize chronic exercise-induced oxidative effects and modulate the exercise effect on mitochondrial changes
4D monitoring of active sinkholes with a Terrestrial Laser Scanner (TLS): A Case study in the evaporite karst of the Ebro Valley, NE Spain
This work explores, for the first time, the application of a Terrestrial Laser Scanner (TLS) and a comparison of point clouds in the 4D monitoring of active sinkholes. The approach is tested in three highly-active sinkholes related to the dissolution of salt-bearing evaporites overlain by unconsolidated alluvium. The sinkholes are located in urbanized areas and have caused severe damage to critical infrastructure (flood-control dike, a major highway). The 3D displacement models derived from the comparison of point clouds with exceptionally high spatial resolution allow complex spatial and temporal subsidence patterns within one of the sinkholes to be resolved. Detected changes in the subsidence activity (e.g., sinkhole expansion, translation of the maximum subsidence zone, development of incipient secondary collapses) are related to potential controlling factors such as floods, water table changes or remedial measures. In contrast, with detailed mapping and high-precision leveling, the displacement models, covering a relatively short time span of around 6 months, do not capture the subtle subsidence (< 0.6-1 cm) that affects the marginal zones of the sinkholes, precluding precise mapping of the edges of the subsidence areas. However, the performance of TLS can be adversely affected by some methodological limitations and local conditions: (1) limited accuracy in large investigation areas that require the acquisition of a high number of scans, increasing the registration error; (2) surface changes unrelated to sinkhole activity (e.g., vegetation, loose material); (3) traffic-related vibrations and wind blast that affect the stability of the scanner
Optimización de las propiedades mecánicas de las aleaciones AlSi7Mg moldeadas en arena
Estudio, medida y mitigación de la concentración de radón en la Escuela Universitaria de Arquitectura Técnica de la Universidade da Coruña
A study of radon concentration has been carried out at the University of A Coruña’s Technical Architecture School. For that purpose, soil and construction materials, as well as building location have been analyzed. After that, measurements have been performed in order to find out radon concentrations. Two techniques have been used to make that enquiry for both short term and long term measurements: for short term, measurements were made using an on-site ionization chamber detector, while, for long term, trace detectors have been employed. Due to the results, and according with the Spanish Law (Spanish Official Bulletin – Boletín Oficial del Estado, of December 21, 2011, IS-33 Instruction), corrective works have taken place (cracks sealing, installation of a forced ventilation system) in order to diminish the high radon concentrations. After works, new measurements proved that radon concentration values lowered about 50 % and 90 %.Se ha llevado a cabo un estudio de la concentración de gas radón en la Escuela Universitaria de Arquitectura Técnica de la Universidade da Coruña. Para ello se ha analizado la ubicación del edificio, el terreno y los materiales de construcción empleados. A continuación se han efectuado mediciones para determinar la concentración de gas radón, empleando dos técnicas: medida in situ con un detector de cámara de ionización (corto espacio de tiempo), y medida con detectores de trazas (largo espacio de tiempo). En función de los resultados obtenidos, y teniendo en cuenta la legislación vigente (BOE, Instrucción IS-33, de 21 de diciembre de 2011), se han efectuado medidas correctoras (sellado de grietas, instalación de un sistema mecánico de ventilación) con el objetivo de mitigar las elevadas concentraciones de radón. Tras la ejecución de dichas medidas correctoras se efectuaron nuevas mediciones, verificándose la mitigación de radón en valores que oscilan entre el 50 y el 90 %
Implementation of the Eclipse Process Framework Composer Tool for the Documentation of Quality Management Systems: A Case Applied in Healthcare Services
This document presents the implementation of the Eclipse Process Framework Composer EPFC tool, in a company in the health sector, which where it were using physical documentation to register the processes QMS Quality Management Systems, in this one it is explained the process of adapting the tool, to migrate the documentary structure of the company, through the application of a model that correlates the attributes of the tool with the documentary structure. The proposed model allows the construction of document structures for the QMS that guide the user in their processes and procedures within the organization. Therefore, it is proposed that by promoting knowledge management and reducing the execution time of the processes, it will be possible for companies to be more productive, improve customer service, failure rates in the development of activities be minimized and, and reduces the lead time in the processes. Finally, it was obtained a documentary platform developed under a process approach that implements interactive diagrams that aim to facilitate the understanding of each of the elements that make up the QMS
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