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Search Results: 1 - 10 of 889 matches for " Nuria Duffo "
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Polarimetric Emission of Rain Events: Simulation and Experimental Results at X-Band
Nuria Duffo,Mercedes Vall llossera,Adriano Camps,Ignasi Corbella,Francesc Torres
Remote Sensing , 2009, DOI: 10.3390/rs1020107
Abstract: Accurate models are used today for infrared and microwave satellite radiance simulations of the first two Stokes elements in the physical retrieval, data assimilation etc. of surface and atmospheric parameters. Although in the past a number of theoretical and experimental works have studied the polarimetric emission of some natural surfaces, specially the sea surface roughened by the wind (Windsat mission), very limited studies have been conducted on the polarimetric emission of rain cells or other natural surfaces. In this work, the polarimetric emission (four Stokes elements) of a rain cell is computed using the polarimetric radiative transfer equation assuming that raindrops are described by Pruppacher-Pitter shapes and that their size distribution follows the Laws-Parsons law. The Boundary Element Method (BEM) is used to compute the exact bistatic scattering coefficients for each raindrop shape and different canting angles. Numerical results are compared to the Rayleigh or Mie scattering coefficients, and to Oguchi’s ones, showing that above 1-2 mm raindrop size the exact formulation is required to model properly the scattering. Simulation results using BEM are then compared to the experimental data gathered with a X-band polarimetric radiometer. It is found that the depolarization of the radiation caused by the scattering of non-spherical raindrops induces a non-zero third Stokes parameter, and the differential phase of the scattering coefficients induces a non-zero fourth Stokes parameter.
Localized corrosion of zirconium and zircaloy- 4 in iodine alcoholic solutions
Farina,S. B.; Duffo,G. S; Galvele,J. R.;
Latin American applied research , 2002,
Abstract: the stress corrosion cracking (scc) susceptibility of zirconium and one of its alloys, zircaloy-4, was studied in 10 g/l iodine dissolved in various alcohols: methanol, ethanol, 1-propanol, 1-butanol and 1-pentanol. scc was observed in all the systems studied and the crack propagation rate was found to vary depending on the size of the solvent molecule. when the molecular weight of the solvent molecule increased, the crack propagation rate decreased. intergranular attack was also found in all the solutions tested, and the rate of intergranular corrosion also varied with the size of the solvent molecule. this behavior is attributed to a steric effect, which hinders the access of the corrosive species to the tip of the crack. the results found agree with the predictions of the surface mobility-scc mechanism.
Localized corrosion of zirconium and zircaloy- 4 in iodine alcoholic solutions
S. B. Farina,G. S Duffo,J. R. Galvele
Latin American applied research , 2002,
Abstract: The stress corrosion cracking (SCC) susceptibility of zirconium and one of its alloys, Zircaloy-4, was studied in 10 g/L iodine dissolved in various alcohols: methanol, ethanol, 1-propanol, 1-butanol and 1-pentanol. SCC was observed in all the systems studied and the crack propagation rate was found to vary depending on the size of the solvent molecule. When the molecular weight of the solvent molecule increased, the crack propagation rate decreased. Intergranular attack was also found in all the solutions tested, and the rate of intergranular corrosion also varied with the size of the solvent molecule. This behavior is attributed to a steric effect, which hinders the access of the corrosive species to the tip of the crack. The results found agree with the predictions of the surface mobility-SCC mechanism.
Consideraciones metodológicas para la interpretación de procesos de interacción en el aula de matemáticas
Planas, Nuria;Iranzo, Nuria;
Revista latinoamericana de investigación en matemática educativa , 2009,
Abstract: in this article, a part of model to analyze the description and interpretation of interactions inside the mathematics classroom is presented. the importance of real classroom cases that contribute to the deconstruction and interpretation of the mathematics classroom is argued from the double prospective of the mathematical content and the social interactions. to do so, the operational use and the integration of notions associated with different theoretical traditions, especially the ones related to mathematical practices, sociomathematical norms, and conflict of meanings are presented. once the analytical model is described, its use is applied to a transcribed episode of a lesson in a secondary classroom of barcelona, spain. finally, reflections about the interest and potential of the model to generate scientific knowledge about the interaction in teaching and learning mathematics situations are discussed.
Infinitesimal initial part of a singular foliation
Corral, Nuria;
Anais da Academia Brasileira de Ciências , 2009, DOI: 10.1590/S0001-37652009000400002
Abstract: this work provides a necessary and sufficient condition to assure that two generalized curve singular foliations have the same reduction of singularities and same camacho-sad indices at each infinitely near point.
Estructura de propiedad y composición de los consejos de administración de los principales grupos de comunicación europeos en 2009
Almiron,Nuria;
Observatorio (OBS*) , 2011,
Abstract: la independencia y autonomía real de los medios de comunicación, especialmente en su quehacer periodístico, está estrechamente vinculada a diversos factores, entre los que destacan la naturaleza de la propiedad empresarial y la libertad o presión bajo la que toman las decisiones los órganos de gobierno corporativos. estos factores, tradicionalmente estudiados principalmente en relación a los lazos y dependencias establecidos por las empresas de comunicación con los grandes anunciantes, asumen una nueva dimensión con la financiarización de los grandes grupos de comunicación. esto es, con la preeminencia de los objetivos financieros -supeditando a los profesionales o vinculados a la responsabilidad democrática- que experimenta la empresa periodística a partir del momento en que ésta empieza a cotizar en bolsa. esta comunicación presenta datos recabados a principios de 2009 sobre la estructura de propiedad y los consejos de administración de los grupos propietarios de medios de comunicación más importantes de europa. la finalidad de este ejercicio es identificar quienes son los sectores económicos conectados con la propiedad y los órganos de gobierno de los propietarios de los principales medios de comunicación que ofrecen contenidos periodísticos en europa.
Estudio clínico-epidemiológico de los brotes de gastroenteritis víricas en Catalu?a
Torner,Nuria;
Revista Espa?ola de Salud Pública , 2009, DOI: 10.1590/S1135-57272009000500007
Abstract: acute gastroenteritis is an important health problem that it affects children and adults, especially the elderly. it is estimated that virus can account for 80% of totality of gastroenteritis. the true magnitude of these processes is difficult to consider since the more or less slight cases usually pass through the systems of notification and monitoring unnoticed. in catalonia 261,222 cases of enteritis and diarrhoeas were declared during 2006, which is equivalent to an incidence rate of 3,661/100,000 persons/year. in order to contribute to a better knowledge of the relevance of gastroenteritis outbreaks caused by norovirus in catalonia, a study was carried out to assess the clinical-epidemiological features of viral gastroenteritis outbreaks occurring during one year. the results obtained indicate that although salmonella is still the most frequent causal agent implied (41%; 74 of 180) in gastroenteritis outbreaks of known aetiology, the second causal agent is norovirus (33.3%; 60 of 180). the greater knowledge of the characteristics and the ascertainment of molecular methods in the diagnosis of these outbreaks translated in a reduction in the number of gastroenteritis outbreaks of any aetiology and especially of those caused by norovirus.
Displayed Dexterity and Distorted Knowledge: Amateurism and Precision in late 18th century Spain
Valverde, Nuria
Asclepio : Revista de Historia de la Medicina y de la Ciencia , 2010,
Abstract: This paper explores the links between scientific practice and precision both in expert networks and popular literature in the second half 18th century Spain. It will be argued that scientific instruments were used and understood in different ways in these two networks, which required opposing strategies for visualizing the degree and goodness of users’ dexterities, thereby fostering the emergence of different collective and individual (epistemic) subjects. I will also argue that these subjects’ differences and affinities were constructed around three themes: firstly, the degree of precision needed to establish a correlation between data and the world, or, in other words, the degree of fluidity admitted in connecting material and cultural worlds; secondly, the relevance attributed to body and bod(il)y knowledge in producing reliable data and stabilizing expertise; and thirdly, the weight attributed to opinion in leaning towards ephemeral or lasting data. The first part of the paper looks at the epistemological and political confluences which in late 18th century Spain nurtured the emergence of both a culture of precision and a sphere of public opinion, and to the strained relationship that existed between them. The other three sections explore how Spanish people used different sets of practices to construct different images of themselves as supporters of a moral of precision. En este artículo se analiza la relación entre el ejercicio científico y la precisión científica tanto en las redes de expertos como en la literatura popular en la Espa a de la segunda mitad del siglo XVIII. Se mostrará que los instrumentos científicos fueron utilizados y comprendidos de diferentes maneras en estas dos redes, lo cual requirió aplicar unas estrategias opuestas para visualizar el grado y la eficacia de las destrezas de los usuarios, y por lo tanto impulsó la emergencia de diferentes sujetos colectivos e individuales (epistémicos). También demostraré cómo estas diferencias y afinidades de sujetos se construyeron alrededor de tres temas: en primer lugar, el grado de precisión necesario para establecer una correlación entre los datos y el mundo o, en otras palabras, el grado de fluidez admitido para conectar el mundo material y el mundo cultural; en segundo lugar, la importancia atribuida al cuerpo y al conocimiento del cuerpo para producir datos fiables y establecer la experiencia; y en tercer lugar, el peso atribuido a la opinión al respaldarse en datos efímeros o duraderos. La primera parte del artículo se centra en las confluencias epistemológicas y políticas que en l
When people live with multiple chronic diseases: a collaborative approach to an emerging global challenge
Nuria Toro
International Journal of Integrated Care , 2011,
Abstract:
María Inés Barbero y Raúl Jacob (eds.), La nueva historia de empresas en América Latina y Espa a
Nuria Puig
América Latina en la historia económica , 2010,
Abstract:
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