690 research outputs found

    Cuantificación de deformaciones recientes en el este de la Península Ibérica mediante la comparación de datos de nivelación de precisión

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    The comparison of the Instituto Geográfico Nacional of Spain high precision levelling data measured during the present century allows us to quantify the ve rtical deformations occurred within this period. The vertical displacements are shown as recent ve rtical movement profiles. We studied the eastern Iberian Peninsula due to its historical and instrumental seismicity and because of the presence a moderate tectonic activity. The magnitude of the vertical movements are according to the recent tectonic activity of each zone, thus the greatest deformations are located at the most tectonic active zones. In the central zone (Valencia Through) tectonic deformations are almost inappreciable, but in the northern (Eastern Pyrenees) and southern (Eastern Betics) zones the average vertical velocities range between 1 and 4 mm/year. In the northern zone the ve rtical anomalies are associated with NW-SE and NE-SW faults with a normal component of movement. In the Eastern Betics the anomalies are related to nearly E-W inverse faults and to NE-SW or NW-SE normal faults. These movements agree with the present day stress tensor (NNW-SSE horizontal compression together with ENE-WSW extension). To confirm the obtained results and to have a better understanding on the main active faults we must carry out new levelling lines and more geological studies

    Orbital phase resolved spectroscopy of 4U1538-52 with MAXI

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    4U 1538-52, an absorbed high mass X-ray binary with an orbital period of 3.73 days, shows moderate orbital intensity modulations with a low level of counts during the eclipse. Several models have been proposed to explain the accretion at different orbital phases by a spherically symmetric stellar wind from the companion. The aim of this work is to study both the light curve and orbital phase spectroscopy of this source in the long term. Particularly, the folded light curve and the changes of the spectral parameters with orbital phase to analyse the stellar wind of QV Nor, the mass donor of this binary system. We used all the observations made from the Gas Slit Camera on board MAXI of 4U 1538-52 covering many orbits continuously. We obtained the good interval times for every orbital phase range which were the input to extract our data. We estimated the orbital period of the system and then folded the light curves and we fitted the X-ray spectra with the same model for every orbital phase spectrum. We also extracted the averaged spectrum of all the MAXI data available. The MAXI spectra in the 2-20 keV energy range were fitted with an absorbed Comptonization of cool photons on hot electrons. We found a strong orbital dependence of the absorption column density but neither the fluorescence iron emission line nor low energy excess were needed to fit the MAXI spectra. The variation of the spectral parameters over the binary orbit were used to examine the mode of accretion onto the neutron star in 4U 1538-52. We deduce a best value of M˙/v=0.65×109\dot{M}/v_\infty=0.65\times 10^{-9} Myr1/(kms1)M_{\odot} \, yr^{-1}/(km \, s^{-1}) for QV Nor.Comment: 12 pages, 5 figures, accepted to be published by A&A, corrected typos (changing bold font to normal one

    An XMM-Newton view of FeK{\alpha} in HMXBs

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    We present a comprehensive analysis of the whole sample of available XMM-Newton observations of High Mass X-ray Binaries (HMXBs) until August, 2013, focusing on the FeK{\alpha} emission line. This line is a key tool to better understand the physical properties of the material surrounding the X-ray source within a few stellar radii (the circumstellar medium). We have collected observations from 46 HMXBs, detecting FeK{\alpha} in 21 of them. We have used the standard classification of HMXBs to divide the sample in different groups. We find that: (1) FeK{\alpha} is centred at a mean value of 6.42 keV. Considering the instrumental and fits uncertainties, this value is compatible with ionization states lower than FeXVIII. (2) The flux of the continuum is well correlated with the flux of the line, as expected. Eclipse observations show that the Fe fluorescence emission comes from an extended region surrounding the X-ray source. (3) FeK{\alpha} is narrow (width lower than 0.15keV), reflecting that the reprocessing material does not move at high speeds. We attempt to explain the broadness of the line in terms of three possible broadening phenomena: line blending, Compton scattering and Doppler shifts (with velocities of the reprocessing material V=1000-2000 km/s). (4) The equivalent hydrogen column (NH) directly correlates with the EW of FeK{\alpha}, displaying clear similarities to numerical simulations. It highlights the strong link between the absorbing and the fluorescent matter. The obtained results clearly point to a very important contribution of the donors wind in the FeK{\alpha} emission and the absorption when the donor is a supergiant massive star.Comment: Accepted for publication in A&A. 13 pages, 16 figures + Appendice

    Production of gaseous and liquid chemicals by aqueous phase reforming of crude glycerol: Influence of operating conditions on the process

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    The present work studies the influence of the temperature (200-240 °C), pressure (38-50 bar), glycerol concentration (10-50 wt.%) and mass of catalyst/ glycerol mass flow rate ratio (W/mglycerol = 10-40 g catalyst min/g glycerol) during the aqueous phase reforming (APR) of a glycerol solution obtained from the production of biodiesel. The operating conditions exerted a statistically significant influence on the reforming results. Specifically, the global glycerol conversion and the carbon converted into gas and liquid products varied as follows: 4-100%, 1-80% and 16-93%, respectively. The gas phase was made up of H2 (8-55 vol.%), CO2 (34-66 vol.%), CO (0-4 vol.%) and CH4 (6-45 vol.%). The liquid phase consisted of a mixture of alcohols (monohydric: methanol and ethanol; and polyhydric: 1, 2-propanediol, 1, 2-ethanediol, 2, 3-butanediol), aldehydes (acetaldehyde), ketones (C3-ketones: acetone and 2-propanone-1-hydroxy; C4-ketones: 2-butanone-3-hydroxy and 2-butanone-1-hydroxy; and cyclic ketones), carboxylic acids (acetic and propionic acids) and esters (1, 2, 3-propanetriol-monoacetate), together with unreacted glycerol and water. The relative amount (free of water and un-reacted glycerol) of these compounds in the liquid phase was as follows: monohydric alcohols: 4-47%, polyhydric-alcohols: 14-68%, aldehydes: 0-5%, C3-ketones: 2-33%, C4-ketones: 0-10%, ciclo-ketones: 0-6%, carboxylic acids: 2-43%, and esters: 0-46%. This process turned out to be highly customisable for the valorisation of crude glycerol for the production of either gaseous or liquid products. Gas production is favoured at a low pressure (39 bar), high temperature (238 °C), high W/mglycerol ratio (38 g catalyst min/g glycerol) and employing a 15 wt.% glycerol solution. A high pressure (45 bar), medium temperature (216 °C), medium W/mglycerol ratio (22 g catalyst min/g glycerol) and the feeding of a 16 wt.% glycerol solution favours the production of liquid products

    3x2 Achievement Goals, Friendship and Affectivity in Physical Education: Age-Gender Differences

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    Se persiguen tres objetivos: (a) analizar las diferencias relativas a la edad y sexo en las metas de logro 3x2, metas de amistad, y afectividad en Educación Física, (b) estudiar las relaciones entre esas variables, y (c) explorar el valor predictivo de las metas de logro 3x2 y amistad sobre la afectividad. La muestra estuvo formada por 1610 alumnos (855 varones y 755 mujeres) de 10 a 17 años. Se realizaron MANOVAS, análisis univariados (Scheffé), y regresiones lineales. Los resultados mostraron un descenso significativo de las metas de logro (excepto aproximación-otro), metas de amistad y afecto positivo debido al desarrollo. Los varones puntuaron más alto las metas de aproximación-tarea, aproximación-otro, y evitación-otro. Las metas de aproximación-tarea y aproximación-amistad fueron los principales predictores positivos del afecto positivo. La franja de 13 a 14 años muestra una gran sensibilidad a los tres estándares de competencia de logro, competencia social e inestabilidad afectivaThe objectives of the study are three: (a) to analyze the differences related to age and sex in the 3x2 achievement goals, the friendship goals, and the affectivity in Physical Education, (b) to study the relationships between these variables, and c) to explore the predictive value of the 3x2 achievement goals and friendship on affectivity. The sample consisted of 1610 students (855 males and 755 females), aged between 10 and 17 years. MANOVAS, univariate analyzes (Scheffé), and linear regressions were performed. The results showed a significant decrease in achievement goals (except other-approach), friendship goals, and positive affect due to development. Males scored higher on task-approach, other-approach, and other-avoidance goals than women. Task-approach and friendship-approach were the main positive predictors of positive affect. The range of 13 to 14 years shows a great sensitivity to the three competences of achievement, social competence, and affective instabilit

    Agroecological analysis of cucumber (Cucumis sativus L.) crops in orchards in a Mediterranean environment

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    If adaptability is defined as the ability of a crop (or variety) to respond positively to changes in agricultural conditions, the purpose of this study was to explore the adaptability and relative influence of environmental factors on Cucumber Sativus L. to a specific Mediterranean environmental and agroecological site: Huete (Cuenca, Central Spain). Cucumber requires high temperatures and soil moisture for a satisfactory yield and maintaining an optimum level of humidity is very favorable, which is easy to achieve for farmers in Huete. Abundant sunshine is needed and this is another reason to cultivate during the summer period; it is estimated that there were between 2700 and 2800 hours of sunshine in the Huete area. The study described here revealed that the soils are poorly developed and evolved, with a simple Ap-C or Ap-Bw-C morphology. The soils are friable, slightly adherent and somewhat dry and hard. A significant feature is the presence of good drainage and appreciable effective depth. Like other crops, cucumber plants are preferably grown on loose, well-drained soils, such as the soils studied here. Huete cucumber seems able to tolerate certain levels of soil salinity when compared to other species. The cucumbers are irrigated with water with moderate electrical conductivity without an appreciable decrease in yield. Small doses of salinity may be one of the factors that leads to the characteristics associated with Huete cucumber, an aspect that would need to be investigated more deeply. Substrate nutrients and moisture management are two major concerns regarding Cucumber Sativus L. crops in Huete. Elemental chemical analysis revealed that strontium abounds and this is attributed to the presence of this element in the gypsums. The results of this study open a new horizon in the study of the aptitude of the land and represent a useful step towards the specific site and, consequently, the sustainable management of land under cucumber cultivation. Further research into a wider range of soils, fertilizer compositions and release rates is require

    Influence of flower head order on phenolic content and quality of globe artichoke at harvest and during twenty-one days of cold storage

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    Artichoke is one of the vegetables with higher content in phenolic compounds, which are responsible for their taste, flavor and health beneficial effects. However, phenolic profile and concentration depends on many factors, such as genotype, harvest date, and environmental and agronomical conditions. The main aim of this study was to perform a phytochemical characterization of artichoke heads, based on their position on plant (main, secondary and tertiary head) and harvest date, during a complete growing season. Results showed that total identified polyphenol concentration was higher in tertiary heads than secondary and main heads, due to their higher concentration in hydroxycinnamic acid and luteolin derivatives. On the other hand, two postharvest storage experiments with main, secondary and tertiary artichoke heads, harvested in winter and spring, were performed. In addition, tertiary head showed the lowest weight, firmness losses and respiration rate during cold storage which could be attributed to their higher antioxidant compounds. In conclusion, tertiary heads have a greater aptitude to be stored at low temperature from harvesting to consumption since they maintained the quality properties for longer period of time and had higher content of bioactive compounds. However, main artichokes are the most appreciated by consumers due to their larger siz

    Cuantificación de ácidos grasos a partir de biomasa microalgal

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    Long chain polyunsaturated fatty acids are focusing the interest of researchers as long as analytical techniques are being improved. The Lepage and Roy direct transesterification method is being widely used to measure fatty acid content of microalgae which are proposed as potential sources of these products. In this paper, the physical state of the biomass to be analyzed is studied. Comparison has been stated between lyophilized biomass and wet biomass just harvested. Furthermore, the amount of sample and the number of methyl ester extractions have also been studied. From the statistical analysis carried out, wet biomass to fatty acid determination and the adequate range of sample are proposed. Three methyl ester extractions improve the resolution of GC analysis.El interés creciente por los ácidos grasos poliinsaturados de cadena larga viene favorecido por la mejora de las técnicas de análisis. La metodología de transesterificación directa propuesta por Lepage y Roy está siendo ampliamente utilizada para la determinación del contenido en ácidos grasos de microalgas, consideradas como potenciales fuentes de estos productos. En el presente trabajo, se analiza la influencia del estado físico de la biomasa analizada, seca, normalmente por liofilización, o húmeda recién cosechada del cultivo. Asimismo, se analiza el efecto de la cantidad de biomasa empleada y del número de extracciones de los esteres metílicos obtenidos. Del estudio estadístico realizado se pone de manifiesto la importancia del estado físico de la muestra, aconsejándose el uso de biomasa directamente obtenida del cultivo. Se proponen los intervalos de cantidad de biomasa para metilación, así como la conveniencia de realizar tres extracciones previas a la inyección en el cromatógrafo, que favorece la resolución del análisis
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