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Search Results: 1 - 10 of 17703 matches for " Miguel Cardenas-Montes "
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Application of GPUs for the Calculation of Two Point Correlation Functions in Cosmology
Rafael Ponce,Miguel Cardenas-Montes,Juan Jose Rodriguez-Vazquez,Eusebio Sanchez,Ignacio Sevilla
Physics , 2012,
Abstract: In this work, we have explored the advantages and drawbacks of using GPUs instead of CPUs in the calculation of a standard 2-point correlation function algorithm, which is useful for the analysis of Large Scale Structure of galaxies. Taking into account the huge volume of data foreseen in upcoming surveys, our main goal has been to accelerate significantly the analysis codes. We find that GPUs offer a 100-fold increase in speed with respect to a single CPU without a significant deviation in the results. For comparison's sake, an MPI version was developed as well. Some issues, like code implementation, which arise from using this option are discussed.
Glass transition and effective potential in the hypernetted chain approximation
Miguel Cardenas,Silvio Franz,Giorgio Parisi
Physics , 1997, DOI: 10.1088/0305-4470/31/9/001
Abstract: We study the glassy transition for simple liquids in the hypernetted chain (HNC) approximation by means of an effective potential recently introduced. Integrating the HNC equations for hard spheres, we find a transition scenario analogous to that of the long range disordered systems with ``one step replica symmetry breaking''. Our result agree qualitatively with Monte Carlo simulations of three dimensional hard spheres.
Constrained Boltzmann-Gibbs measures and effective potential for glasses in hypernetted chain approximation and numerical simulations
Miguel Cardenas,Silvio Franz,Giorgio Parisi
Physics , 1998, DOI: 10.1063/1.478028
Abstract: By means of an effective potential associated to a constrained equilibrium measure and apt to study frozen systems, we investigate glassy freezing in simple liquids in the hypernetted chain (HNC) approximation. Differently from other classical approximations of liquid theory, freezing is naturally embedded in the HNC approximation. We get a detailed description of the freezing transition that is analogous to the one got in a large class of mean-field long range spin glass. We compare our findings with Monte Carlo simulations of the same system and conclude that many of the qualitative features of the transition are captured by the approximated theory.
Perfil biopsicosocial de la madre y su relación con el abandono de lactancia materna exclusiva
Cardenas,M.H.; Montes,E.; Varon,M.; Arenas,N.; Reina,R.;
Enfermería Global , 2010, DOI: 10.4321/S1695-61412010000300004
Abstract: exclusive maternal lactation is a form of infant nutrition without equal. nevertheless, in spite of the importance of exclusive maternal lactation; at the present time a problem of its early abandonment exists due to the lack of effective policies for its promotion. the objective of this investigation was to establish if a relation between the bio-psychosocial profile of the mother and the abandonment of exclusive maternal lactation exists. the methodology was framed within the quantitative design, of cross section correlation type. the population was 106 mothers of children under the age of six months that visited the pediatrics department of the health unit dr. diaz carballo and the medical group miranda, the sample was representative of the whole conformed by 60 mothers, distributed in two groups: 30 mothers who gave exclusive maternal lactation and 30 that had stopped. data appear in graphs of percentages using statistics of the square of chi with correction of yates. results: the age, the psychological aspect, the habits of the mother maintain a statistically significant relation with the abandonment of exclusive maternal lactation. one concludes that the bio-psychosocial factors (age, parity, psychological aspect, and culture) can become obstacles to the mother practicing exclusive a maternal lactation. the social aspect (social status) does not have relevance to the abandonment of exclusive maternal lactation, similarly to the origin of the mother.
A unified approach to pricing and risk management of equity and credit risk
Claudio Fontana,Juan Miguel A. Montes
Quantitative Finance , 2012, DOI: 10.1016/j.cam.2013.04.047
Abstract: We propose a unified framework for equity and credit risk modeling, where the default time is a doubly stochastic random time with intensity driven by an underlying affine factor process. This approach allows for flexible interactions between the defaultable stock price, its stochastic volatility and the default intensity, while maintaining full analytical tractability. We characterise all risk-neutral measures which preserve the affine structure of the model and show that risk management as well as pricing problems can be dealt with efficiently by shifting to suitable survival measures. As an example, we consider a jump-to-default extension of the Heston stochastic volatility model.
Crecimiento del mejillón verde Perna viridis (Bivalvia: Mytilidae) bajo sistema de cultivo de fondo en la ensenada de Turpialito, Golfo de Cariaco, Venezuela Growth and survival of the green mussel P. viridis (Bivalvia: Mytilidae) in bottom culture conditions in Turpialito, Golfo de Cariaco, Venezuela
Vanessa Acosta,Marbelis Montes,Roraysi Cortez,Miguel Guevara
Revista de Biología Tropical , 2012,
Abstract: Los moluscos representan uno de los grupos más importantes desde el punto de vista económico en la acuicultura marina, debido a los bajos costos de producción y a su alta rentabilidad. En este estudio se planteó probar la hipótesis de un mayor crecimiento de Perna viridis en cultivo de fondo, por un mejor aprovechamiento de alimento presente en el medio, lo cual permitirá descartarla o no como especie de cultivo para el Golfo de Cariaco. En este sentido, se evaluó el crecimiento y la supervivencia del mejillón verde P. viridis en condiciones de cultivo de fondo entre julio 2007 y febrero 2008. Las semillas del mejillón (35.81±1.41mm de longitud) fueron obtenidas en la localidad de Guaca (costa norte del estado Sucre) y trasladadas hasta la Estación Hidrobiológica de Turpialito, golfo de Cariaco, estado Sucre-Venezuela, en donde se sembraron en cestas “espa olas”. Mensualmente se determinó supervivencia así como la longitud máxima de la concha, la masa seca del músculo, resto de tejidos y de la gónada. Los parámetros ambientales (temperatura del agua, salinidad, oxígeno disuelto, clorofila a, seston total y su fracción orgánica), en la zona de cultivo se determinaron cada 15 días. Mensualmente se realizaron determinaciones de proteínas, lípidos y carbohidratos al seston. Durante todo el estudio el mejillón mantuvo un crecimiento continuo, alcanzando al final una longitud máxima de 78.7±4.43mm. Sin embargo, la tasa de crecimiento de la masa seca de los tejidos somáticos (músculo, resto de tejido) y reproductivo, mostraron variabilidad a lo largo del estudio, produciéndose al final un incremento significativo en dichos tejidos. Las variaciones observadas en la tasa de crecimiento de la masa del tejido reproductivo, dependió de las reservas acumuladas y del alimento ofertado por el medio ambiente. El seston orgánico durante toda la experiencia mostró una independencia de la temperatura y de la clorofila a manteniendo valores por encima de 1mg/L, constituyendo de esta manera el principal recurso alimenticio para los mejillones. Los altos contenidos de proteínas, lípidos y carbohidratos observados en el seston al final del estudio, pudieran estar principalmente asociados con la surgencia costera que provee un gran aporte alimenticio de tipo fitoplanctónico y orgánico. El alto porcentaje de supervivencia (>80%), el incremento de la longitud de la concha y la alta producción de tejido reproductivo, sugieren una excelente condición fisiológica de P. viridis, relacionada con la disponibilidad y la calidad del alimento particularmente de tipo orgánico presente en e
Noticias y Experiencias
del Saz, Miguel ángel,Montes López, Evelio
Revista Espa?ola de Documentación Científica , 2000,
Open learning recognition in traditional universities
Rosana Montes Soldado,Miguel Gea Megías,Jeff Haywood
Journal for Educators, Teachers and Trainers , 2013,
Abstract: At present, there is great interest over the concept of Open Educational Resources (OER) in all of its forms: OpenCourseware repositories OCW, spare open resources, or even more recently as Massive Online Open Courses (also called MOOC). This panorama has generated considerable debate about their effectiveness in terms of learning, sustainability and especially the role that higher education institutions play in this context. We understand that most of the students are interested in making the most of their education (formal and informal), and that will require universities to recognize their skills and abilities. In this article we start from the point of view of the university as a certifying OER-based institution, and we describe the different scenarios that arises. First of all the institution should know what is facing and what are the existing scenarios. From the experience of the European project OERtest, in which five higher education institutions have conducted a pilot on this issue, we can offer some conclusions regarding the feasibility of certifying and award credits to a student (internal or external to the institution when this service is requested.
Arbuscular Mycorhizal Fungi Associated with the Olive Crop across the Andalusian Landscape: Factors Driving Community Differentiation
Miguel Montes-Borrego, Madis Metsis, Blanca B. Landa
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0096397
Abstract: Background In the last years, many olive plantations in southern Spain have been mediated by the use of self-rooted planting stocks, which have incorporated commercial AMF during the nursery period to facilitate their establishment. However, this was practised without enough knowledge on the effect of cropping practices and environment on the biodiversity of AMF in olive orchards in Spain. Methodology/Principal Findings Two culture-independent molecular methods were used to study the AMF communities associated with olive in a wide-region analysis in southern Spain including 96 olive locations. The use of T-RFLP and pyrosequencing analysis of rDNA sequences provided the first evidence of an effect of agronomic and climatic characteristics, and soil physicochemical properties on AMF community composition associated with olive. Thus, the factors most strongly associated to AMF distribution varied according to the technique but included among the studied agronomic characteristics the cultivar genotype and age of plantation and the irrigation regimen but not the orchard management system or presence of a cover crop to prevent soil erosion. Soil physicochemical properties and climatic characteristics most strongly associated to the AMF community composition included pH, textural components and nutrient contents of soil, and average evapotranspiration, rainfall and minimum temperature of the sampled locations. Pyrosequencing analysis revealed 33 AMF OTUs belonging to five families, with Archaeospora spp., Diversispora spp. and Paraglomus spp., being first records in olive. Interestingly, two of the most frequent OTUs included a diverse group of Claroideoglomeraceae and Glomeraceae sequences, not assigned to any known AMF species commonly used as inoculants in olive during nursery propagation. Conclusions/Significance Our data suggests that AMF can exert higher host specificity in olive than previously thought, which may have important implications for redirecting the olive nursery process in the future as well as to take into consideration the specific soils and environments where the mycorrhized olive trees will be established.
Disentangling Peronospora on Papaver: Phylogenetics, Taxonomy, Nomenclature and Host Range of Downy Mildew of Opium Poppy (Papaver somniferum) and Related Species
Hermann Voglmayr, Miguel Montes-Borrego, Blanca B. Landa
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0096838
Abstract: Based on sequence data from ITS rDNA, cox1 and cox2, six Peronospora species are recognised as phylogenetically distinct on various Papaver species. The host ranges of the four already described species P. arborescens, P. argemones, P. cristata and P. meconopsidis are clarified. Based on sequence data and morphology, two new species, P. apula and P. somniferi, are described from Papaver apulum and P. somniferum, respectively. The second Peronospora species parasitizing Papaver somniferum, that was only recently recorded as Peronospora cristata from Tasmania, is shown to represent a distinct taxon, P. meconopsidis, originally described from Meconopsis cambrica. It is shown that P. meconopsidis on Papaver somniferum is also present and widespread in Europe and Asia, but has been overlooked due to confusion with P. somniferi and due to less prominent, localized disease symptoms. Oospores are reported for the first time for P. meconopsidis from Asian collections on Papaver somniferum. Morphological descriptions, illustrations and a key are provided for all described Peronospora species on Papaver. cox1 and cox2 sequence data are confirmed as equally good barcoding loci for reliable Peronospora species identification, whereas ITS rDNA does sometimes not resolve species boundaries. Molecular phylogenetic data reveal high host specificity of Peronospora on Papaver, which has the important phytopathological implication that wild Papaver spp. cannot play any role as primary inoculum source for downy mildew epidemics in cultivated opium poppy crops.
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