794 research outputs found

    Opciones estratégicas de las agencias de noticias europeas: Reuters, France Presse y EFE

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    Las agencias de noticias se enfrentan a una nueva realidad internacional y de mercado en el siglo XXI. Los cambios políticos, económicos, tecnológicos y sociales que ya ha provocado y sigue produciendo la globalización obligan a estas empresas de comunicación a adaptarse a un entorno muy diferente del que han vivido en el último siglo. Cuestiones clave que deben resolver de un modo estratégico son su relación con los gobiernos; su independencia editorial, comercial y financiera; y la apertura a nuevos productos y clientes distintos de los medios de comunicación tradicionales

    Mating system in a natural population of Theobroma grandiflorum (Willd. ex Spreng.) Schum., by microsatellite markers.

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    The aim of this research was to study the mating system of a natural population of Theobroma grandiflorum (cupuassu) from Nova Ipixuna, Pará state, using microsatellite markers. Eight polymorphic microsatellite loci were analyzed in eight families, each represented by 10 six-month old seedlings derived from open-pollinated pods. The estimation for the multilocus outcrossing rate (tm=1.0)andindividualoutcrossingrate(tm= 1.0) and individual outcrossing rate (t= 1.0) for this population suggests that T. grandiflorum may be a perfect outbreeding (allogamous) species. Likewise, for the studied population the estimate for single locus outcrossing rate (ts)waselevated(0.946),butlowerthants) was elevated (0.946), but lower than tm, confirming the likely outcrossing character of the species and suggesting the occurrence of 5.4% biparental inbreeding rate (tmtm-ts). The estimation of genetic divergence (FST)betweenallelicfrequenciesinovulesandpollenrevealedadeviationfromrandommatingin75FST) between allelic frequencies in ovules and pollen revealed a deviation from random mating in 75% of the evaluated loci. Likewise, the estimate of correlation of paternity (rp= 0.930) and the mean coefficient of co-ancestrality within families ($?xy= 0.501) indicated that the outcrossings were predominantly correlated, and the offspring were full-sibs. These results suggested that for this particular population of T. grandiflorum, the sampling strategy for genetic conservation and breeding should adopt specific models for families derived from correlated outcrossing (full-sibs) and not the ones usually adopted in classic outcrossing species breeding programs (half-sibs)

    A nanoporous surface is essential for glomerular podocyte differentiation in three-dimensional culture.

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    Although it is well recognized that cell-matrix interactions are based on both molecular and geometrical characteristics, the relationship between specific cell types and the three-dimensional morphology of the surface to which they are attached is poorly understood. This is particularly true for glomerular podocytes - the gatekeepers of glomerular filtration - which completely enwrap the glomerular basement membrane with their primary and secondary ramifications. Nanotechnologies produce biocompatible materials which offer the possibility to build substrates which differ only by topology in order to mimic the spatial organization of diverse basement membranes. With this in mind, we produced and utilized rough and porous surfaces obtained from silicon to analyze the behavior of two diverse ramified cells: glomerular podocytes and a neuronal cell line used as a control. Proper differentiation and development of ramifications of both cell types was largely influenced by topographical characteristics. Confirming previous data, the neuronal cell line acquired features of maturation on rough nanosurfaces. In contrast, podocytes developed and matured preferentially on nanoporous surfaces provided with grooves, as shown by the organization of the actin cytoskeleton stress fibers and the proper development of vinculin-positive focal adhesions. On the basis of these findings, we suggest that in vitro studies regarding podocyte attachment to the glomerular basement membrane should take into account the geometrical properties of the surface on which the tests are conducted because physiological cellular activity depends on the three-dimensional microenvironment

    The effects of environment on Arctica islandica shell formation and architecture

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    Mollusks record valuable information in their hard parts that reflect ambient environmental conditions. For this reason, shells can serve as excellent archives to reconstruct past climate and environmental variability. However, animal physiology and biomineralization, which are often poorly understood, can make the decoding of environmental signals a challenging task. Many of the routinely used shell-based proxies are sensitive to multiple different environmental and physiological variables. Therefore, the identification and interpretation of individual environmental signals (e.g., water temperature) often is particularly difficult. Additional proxies not influenced by multiple environmental variables or animal physiology would be a great asset in the field of paleoclimatology. The aim of this study is to investigate the potential use of structural properties of Arctica islandica shells as an environmental proxy. A total of 11 specimens were analyzed to study if changes of the microstructural organization of this marine bivalve are related to environmental conditions. In order to limit the interference of multiple parameters, the samples were cultured under controlled conditions. Three specimens presented here were grown at two different water temperatures (10 and 15 °C) for multiple weeks and exposed only to ambient food conditions. An additional eight specimens were reared under three different dietary regimes. Shell material was analyzed with two techniques; (1) confocal Raman microscopy (CRM) was used to quantify changes of the orientation of microstructural units and pigment distribution, and (2) scanning electron microscopy (SEM) was used to detect changes in microstructural organization. Our results indicate that A. islandica microstructure is not sensitive to changes in the food source and, likely, shell pigment are not altered by diet. However, seawater temperature had a statistically significant effect on the orientation of the biomineral. Although additional work is required, the results presented here suggest that the crystallographic orientation of biomineral units of A. islandica may serve as an alternative and independent proxy for seawater temperature

    La inoculación de Azospirillum brasilense mejora la calidad de las plántulas de un mezquite (Prosopis juliflora)

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    Inoculation of mycorrhizal fungi and rhizobacteria in plants can improve their growth and physiological status, which could be particularly important for agricultural and forestry plants used for the revegetation of arid areas. Prosopis juliflora is a forest pioneer species that is drought resistant and has multiple uses (fodder, shade and shelter for livestock; timber and firewood, live fences and windbreaks in agroforestry systems). Azospirillum brasilense is a rhizobacterium that improves the growth of many agricultural crops. The hypothesis of this study was that P. juliflora seedlings produced in the nursery can respond positively to inoculation with A. brasilense CECT 590. Five months after inoculation, we examined the growth, water relations (osmotic potential at full turgor, osmotic potential at zero turgor, and the modulus of elasticity at full turgor), and concentration and content of macronutrients (N, P, K, Ca and Mg) in the seedlings. Subsequently, a trial was conducted to analyse root growth potential. A. brasilense CECT 590 inoculation caused an osmotic adjustment in P. juliflora seedlings but decreased the elasticity of the cell walls. Inoculation with A. brasilense CECT 590 significantly improved plant growth due in part to an increase of N concentration in the seedlings. A. brasilense CECT 590 inoculation also caused an increase in the root growth potential. The increased growth of P. juliflora seedlings inoculated with A. brasilense was probably caused by more than one mechanism. Inoculation with A. brasilense at the nursery may be a suitable technique for producing improved seedling material for restoration purposes.La inoculación de hongos de micorrizacion y rizobacterias en las plantas puede mejorar su crecimiento y calidad fisiológica, especialmente en plantas agrícolas y forestales empleadas para la regeneración de zonas áridas. Prosopis juliflora es una especie forestal pionera, resistente a la sequía, y de usos múltiples (forraje, sombra y cobijo para el ganado, madera y leña, cercas vivas y cortinas cortavientos en sistemas agroforestales). Azospirillum brasilense es una rizobacteria que mejora el crecimiento de muchos cultivos agrícolas. La hipótesis de este estudio fue que las plántulas de P. juliflora producidas en vivero pueden responder positivamente a la inoculación con A. brasilense CECT 590. Cinco meses después desde la inoculación, se analizó el crecimiento, relaciones hídricas (potencial osmótico en saturación, potencial osmótico en el punto de pérdida de turgencia, y módulo de elasticidad a total turgor), concentración y contenido de macronutrientes (N, P, K, Ca y Mg) en las plántulas. Posteriormente se realizó un ensayo para analizar el Potencial de Crecimiento Radical. La inoculación de A. brasilense CECT 590 causó un ajuste osmótico de las plántulas de P. juliflora, pero disminuyó la elasticidad de las paredes celulares. A. brasilense CECT 590 mejoró significativamente el crecimiento de la planta, debido en parte al incremento de la concentración de N en las plántulas. La inoculación con A. brasilense CECT 590 también causó un incremento del potencial de crecimiento radical. El incremento del crecimiento en las plántulas de P. juliflora inoculadas con A. brasilense fue probablemente debido a más de un mecanismo. La inoculación con A. brasilense en vivero puede ser una técnica adecuada para la producción de material de plántulas mejorado con fines de restauración

    Media Concentration in Spain: National, sectorial, and regional groups

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    In Spain, the media market structure is made up of very different media groups, making it necessary to identify and classify them in a clear and coherent manner. To do so, this article collects secondary information from media companies'' websites and from audience measurement institutions. Results identify 50 media groups with activity in the Spanish market. They are classified into three categories according to the type of outlet, including national, sectorial, and regional. The current structure is based on recent developments in the last four decades of democracy among newspapers, magazines, radio, television and digital media. © 2021 Universidad Complutense de Madrid. All rights reserved

    Utility of international normative 20 m shuttle run values for identifying youth at increased cardiometabolic risk

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    The purpose of this study was to examine the ability of international normative centiles for the 20 m shuttle run test (20mSRT) to identify youth at increased cardiometabolic risk. This was a cross-sectional study involving 961 children aged 10–17 years (53% girls) from the United Kingdom. Receiver operating characteristic (ROC) curves determined the discriminatory ability of cardiorespiratory fitness percentiles for predicting increased cardiometabolic risk. ROC analysis demonstrated a significant but poor discriminatory accuracy of cardiorespiratory fitness in identifying low/high cardiometabolic risk in girls (AUC = 0.58, 95% CI: 0.54–0.63; p = 0.04), and in boys (AUC = 0.59, 95% CI: 0.54–0.63; p = 0.03). The cardiorespiratory fitness cut-off associated with high cardiometabolic risk was the 55th percentile (sensitivity = 33.3%; specificity = 84.5%) in girls and the 60th percentile (sensitivity = 42.9%; specificity = 73.6%) in boys. These 20mSRT percentile thresholds can be used to identify children and adolescents who may benefit from lifestyle intervention. Nonetheless, further work involving different populations and cardiometabolic risk scores comprising of different variables are needed to confirm our initial findings
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