Hot carrier and hot phonon coupling during ultrafast relaxation of photoexcited electrons in graphene

We study, by means of a Monte Carlo simulator, the hot phonon effect on the relaxation dynamics in photoexcited graphene and its quantitative impact as compared to considering an equilibrium phonon distribution. Our multi-particle approach indicates that neglecting the hot phonon effect significantly underestimates the relaxation times in photoexcited graphene. The hot phonon effect is more important for a higher energy of the excitation pulse and photocarrier densities between $1$ and $3\times 10^{12} \mathrm{~cm}^{-2}$. Acoustic intervalley phonons play a non-negligible role, and emitted phonons with wavelengths limited up by a maximum (determined by the carrier concentration) induce a slower carrier cooling rate. Intrinsic phonon heating is damped in graphene on a substrate due to additional cooling pathways, with the hot phonon effect showing a strong inverse dependence with the carrier density.Comment: 12 pages, 5 figure

Almacenamiento de información sobre fondos audiovisuales subtitulados y audiodescritos: la importancia de una estructuración adecuada del conocimiento

Actas de: II Congreso de Accesibilidad a los Medios Audiovisuales para Personas con Discapacidad (AMADIS'07), celebrado en Granada del 21 al 22 de Junio de 2007.Publicad

Construyendo un Sistema de Educación Adaptativo e Inteligente en Web para aprendizaje de Diseño de Bases de Datos

VIII Jornadas de Ingeniería del Software y Bases de Datos (JISBD'03). Celebradas en la Universitat d'Alacant (Alicante) del 12 al 14 de noviembre de 2003En este artículo se presenta la arquitectura de un Sistema de Educación Adaptativo e Inteligente en web (SEAI en web) para la enseñanza de Diseño de Bases de Datos. Este sistema se enmarca dentro del proyecto de investigación PANDORA, cuyo objetivo principal es definir métodos y técnicas para el desarrollo de bases de datos implementadas en una herramienta CASE, donde uno de los módulos del proyecto se centra en la enseñanza de esta materia vía web. Además se proporciona una breve descripción de los módulos del dominio y del módulo del interfaz del SEAI.Este trabajo es parte del proyecto de investigación PANDORA (Plataforma CASE para el Desarrollo de Bases de Datos y Aprendizaje vía Internet), proyecto CICYT (TIC99-0215).Publicad

Repertorios bibliográficos (XVII) Ensayo de una bibliográfia comentada de manuales de artes, ciencias, oficios, costumbres públicas y privadas de España (Siglos XVI al XIX)

Estudio del “Ensayo de una bibliografía comentada de manuales …” realizado por Vicente Castañeda y publicado en el año 1955 por la Real Academia de la Historia. El ensayo recoge las obras que coleccionaba el autor de libros de divulgación, tratados y manuales de todo tipo sobre conocimientos populares en materia científica, artística, costumbres, diversiones y oficios manuales que se publicaban en 8º principalmente

Compact loaded PIFA for multifrequency applications

A new multifrequency microstrip patch antenna is presented. The antenna can be considered a PIFA since it has a metallic wall on one of its sides. The different bands of operation are independent of each other, and different radiation patterns for each band can be achieved if desired. In addition, a circuital model is introduced to explain the operation of the antenna. This model presents some similarities with composite right left handed models presented in the literature. Some prototypes have been manufactured and measurements of return losses, efficiencies and radiation patterns, have been performed for a thorough characterization of the antenna as well as to validate the simulation results

New Microstrip Gap Waveguide on Mushroom-Type EBG for Packaging of Microwave Components

The gap waveguide has been recently presented as a new transmission line technology using artificial magnetic conductors (AMCs) to allow the wave propagation only along a desired path. The first validation has been provided using a lid of metal pins as AMC for high frequency applications. In this letter, simulations and measurement results are presented for another version called microstrip gap waveguide, working as inverted microstrip line and realized using a mushroom-type EBG surface. The transmission line is surrounded by mushrooms which create a parallel plate stop band, suppressing cavity modes and unwanted radiations compared to standard packaged microstrip transmission lines. The field propagates in the air gap between the upper lid and the mushrooms layer, providing a low loss compact circuit made in printed technology

Automatic Identification of Biomedical Concepts in Spanish Language Unstructured Clinical Texts

[Poster]. IHI'10 ACM International Health Informatics Symposium Arlington, VA, USA - November 11-12, 2010The processing of health information from medical records and, especially, clinical notes is a complex task due to the nature of the texts themeselves (i.e., hand-written and containing semi-structured or unstructured data) and the diversity of the terminology used. While certain technologies exist to process these types of texts and data in the English language, only a few such initiatives exist for similar texts and data in the Spanish language. This paper presents a new proposal for the semantic annotation of Spanish-language clinical notes, implementing an automated tool similar to the UMLS MetaMap Transfer (MMTx) for the identification of biomedical concepts in the Spanish-language SNOMED CT ontology. Moreover, an assessment of the tool using 100 Spanish-language clinical notes is presented. Using the clinical notes manually annotated by specialists of a Spanish hospital as the gold standard, it is concluded that precision scores are sufficiently good for the several types of matching achieved by the automated tool proposed. The research presented in this contribution offers a launching point for the establishment of semantic relationships between concepts and the application of mining techniques to Spanish-language clinical notes.This study has been partially supported by the MAVIR Consortium (S2009/TIC-1542) and by the TIN2007-67407-C03-01 project BRAVOPublicad

Evaluation of losses in microstrip gap waveguide for slot antennas applications

The new microstrip gap waveguide supports a quasi-TEM mode in the air by the use of artificial magnetic conductors which force the field to travel in the air rather than in the substrate. This paper presents an evaluation of losses by measuring the Q-factor of a resonator made in this technology, made using a mushroom-type EBG surface. Losses are crucial when using printed circuits to feed slot antennas, thereby motivating this work. Comparisons with standard microstrip lines will be provided, showing promising results

Patagonia’s diverse but homogeneous early paleocene forests: Angiosperm leaves from the Danian Salamanca and Peñas Coloradas formations, San Jorge Basin, Chubut, Argentina

Early Paleocene macrofloras from the Southern Hemisphere are little known, despite their significance for understanding plant evolution, biogeography, and global variation in recovery after the end-Cretaceous extinction. As a foundation for systematic and paleoecological work, we describe 51 angiosperm leaf morphotypes from three distinct, precisely dated early to late Danian time intervals, using collections from the Salamanca and Peñas Coloradas formations in the San Jorge Basin, Chubut Province, Patagonia, Argentina. These rich floras were previously analyzed but with minimal descriptions. The assemblages comprise the first stratigraphically controlled and quantitatively collected floras for the early Paleocene of the Southern Hemisphere. Botanical affinities of the angiosperm morphotypes are not formally assigned here, but we informally associate some of them with families including Arecaceae, Fabaceae, Cunoniaceae, Lauraceae, Nothofagaceae, Rhamnaceae, and Rosaceae; in addition, leaves of Menispermaceae and other Rhamnaceae were formally described in previous work. Other families potentially present in these assemblages include Akaniaceae, Anacardiaceae, Apiaceae, Araceae, Bixaceae, Juglandaceae, Malvaceae, Sapindaceae, and Urticaceae. Remarkably, there is little floral turnover or change in dominance through the Danian floral sequence spanned by the studied localities, even among estuarine vs. continental depositional environments. This finding indicates a homogeneous, generalist, long-lived floral association following the K-Pg extinction, similar in these respects to many North American Danian floras. However, the richness of the Danian Patagonian floras, from paleolatitudes >50 degrees South, along with other lines of evidence from the region, suggests differences in the response of terrestrial ecosystems in southern South America to the terminal Cretaceous event from those of the Northern Hemisphere. The flora appears to be largely paleo-endemic in nature and shows several compositional links to the Eocene floras of Patagonia, emphasizing the importance of diversification within Patagonia after the end-Cretaceous event as a factor leading to the hyperdiverse Eocene regional floras.Fil: Iglesias, Ari. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Wilf, Peter. State University of Pennsylvania; Estados UnidosFil: Stiles, Elena. State University of Pennsylvania; Estados Unidos. University of Washington; Estados UnidosFil: Wilf, Rebecca. State University of Pennsylvania; Estados Unido

Prevalence of musculoskeletal disorders in children´s foot: preliminary study

A la edad escolar ya se tiene la marcha, la funcionalidad y la morfología del pie característica del adulto pero aún no está completada la madurez esquelética. Esto hace que sea una edad propicia para realizar una adecuada prevención y un diagnóstico precoz de las alteraciones musculoesqueléticas de los pies y miembros inferiores. Hemos realizado un estudio transversal de prevalencia para conocer el estado de salud de los pies de los escolares. Se han evaluado 116 niños mediante una observación clínica y un estudio de la marcha con una plataforma de presiones. Los resultados más llamativos fueron que al 93% nunca se les había realizado una exploración similar, el 95% tenía alterado el reparto de presiones de la huella, un 75% presentaba alguna alteración en la dinámica (la más frecuente excesiva pronación en la fase de propulsión) y el mismo porcentaje de niños llevaban el calzado de talla pequeña. Más de la mitad tenía una huella anormal y el pie excesivamente pronado. Un 40% presentaba dolor, el 35% tenía pie cavo y un 10% pie plano. El 32% tenía alguna patología de antepie. El resto de alteraciones fueron menos frecuentes. Hemos encontrado una alta prevalencia de alteraciones, por lo que se evidencia una vez más la necesidad de hacer controles periódicos a estas edades e incluirlos dentro de los programas de educación para la salud y prevenir futuras complicaciones.At school age, children already have the functionality and foot morphology of adult but have not yet completed skeletal maturity. This makes it a proper age for appropriate prevention and early diagnosis of musculoskeletal disorders of the feet and lower limbs. We conducted a cross-sectional study of prevalence for the health of the feet of the schoolaged children. 116 children have been assessed by clinical observation and a study of gait with a pressure platform. The most striking results were that 93% never had made a similar exploration, 95% had altered pressure distribution footprint, 75% showed some alteration in the dynamics (the most frequent excessive pronation phase propulsion) and the same percentage of children wearing shoes small size. More than half had an abnormal trace excessively pronated foot. Meanwhile, 40% had pain, 35% had pes cavus and flatfoot 10%. Finally, 32% had one forefoot pathology. The remaining changes were less frequent. We found a high prevalence of alterations so it is further evidence of the need for regular checks at this age to prevent complications and implement programs of health education