WorldWideScience

Sample records for acopladas entre si

  1. ACOPLAMIENTO EXCITATORIO E INHIBITORIO DE NEURONAS PULSANTES ACOPLADAS

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    Francis Armando Segovia Chaves

    2012-05-01

    Full Text Available La información es representada como patrones de actividad neuronal o pulsos, lo que crea una diferencia significante entre las redes neuronales pulsantes y las redes neuronales clásicas. Una característica diferente de las redes neuronales pulsantes es que la información es codificada en patrones de actividad neuronal y estas se comunican usando trenes de pulsos en lugar de valores individuales. Además, este tipo de redes neuronales pulsantes trabajan con una gran cantidad de neuronas donde se requiere grandes recursos computacionales para ser simuladas. En el presente trabajo se realiza un análisis teórico de las redes neuronales pulsantes,  para el caso de dos neuronas acopladas. Se logra obtener teóricamente las condiciones para acoplamiento excitatorio e inhibitorio en las neuronas.

  2. Produção de sentidos entre adolescentes sobre o cuidado de si na gravidez

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    Nayara Bueno de Araujo

    2016-06-01

    Full Text Available No pré-natal, profissionais comumente desconsideram a rede de produção de sentidos de adolescentes sobre o cuidado de si na gravidez. Busca-se evidenciá-la em uma situação concreta, com foco nas fontes e comunidades de referência para adolescentes de áreas pobres de Cuiabá-MT, Brasil, sintetizadas em um mapa. Trata-se de estudo qualitativo, realizado entre 2014-2015, com 12 adolescentes grávidas, por meio de: grupo focal, entrevista individual, consulta a prontuários e análise baseada em preceitos e categorias da Análise de Discurso Crítica. A principal comunidade discursiva de referência das adolescentes é a família, embora profissionais de saúde, mídia e conhecidos também intermedeiem a construção de seus discursos. A cultura biomédica e o cuidado, como controle de riscos via comportamentos, são, respectivamente, as fontes e as vozes mais relevantes dentre outras concorrentes. Entender essas peculiaridades propicia ao profissional buscar melhores formas de relacionar-se com adolescentes e ampliar sua autonomia.

  3. ACOPLAMIENTO EXCITATORIO E INHIBITORIO DE NEURONAS PULSANTES ACOPLADAS

    OpenAIRE

    Francis Armando Segovia Chaves; Silvia Catalina Corrales Martínez

    2012-01-01

    La información es representada como patrones de actividad neuronal o pulsos, lo que crea una diferencia significante entre las redes neuronales pulsantes y las redes neuronales clásicas. Una característica diferente de las redes neuronales pulsantes es que la información es codificada en patrones de actividad neuronal y estas se comunican usando trenes de pulsos en lugar de valores individuales. Además, este tipo de redes neuronales pulsantes trabajan con una gran cantidad de neuronas donde s...

  4. Base nacional curricular comum: a falsa oposição entre conhecimento para fazer algo e conhecimento em si

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    Elizabeth Macedo

    2016-06-01

    Full Text Available RESUMO: Assumindo uma visão da política como processo de signifiXação a partir da teoria do discurso de Ernesto Laclau e Chantal Mouffe, foco o atual debate sobre bases nacionais curriculares comuns no Brasil. Sendo o antagonismo social inerradicável, defendo que o terreno político é sempre marcado por articulações entre uma pluralidade de demandas. Utilizo a experiência da Austrália como ponto de partida para destacar duas ideias que se antagonizam nas discussões sobre base curricular comum no Brasil, quais sejam: conhecimento para fazer algo e conhecimento em si. Após analisar a oposição entre elas, argumento que a disputa naturaliza o sentido de currículo como controle, ideia que tento deslocar entendendo educação, justiça e democracia como porvir.

  5. Entre Freud e Foucault: a resistência como afirmação de si

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    Fernanda Canavêz

    2015-07-01

    Full Text Available O artigo dedica-se ao tema da resistência para extrapolar seu entendimento como ponto de estagnação da experiência da análise. Ao contrário, o objetivo é sustentá-la como movimento de afirmação de si, de subjetivação. Para a consecução dessa proposta considera-se a multiplicidade das resistências colocada no momento mais tardio da obra freudiana para a realização de uma leitura acerca da noção no pensamento de Foucault. Nesse contexto, a resistência apresenta-se intimamente atrelada ao poder - que na perspectiva foucaultiana ultrapassa o modelo jurídico para se capilarizar nas malhas do social -, relação cujos termos não se anulam dialeticamente. A resistência figura, assim, como operador da liberdade do sujeito ante as estruturas de dominação. Por fim, aposta-se na potência da experiência psicanalítica como movimento de construção permanente dos mais diversos modos de si. As resistências seriam, portanto, o elemento a assegurar a insubmissão a uma subjetividade forjada.

  6. Estudo de associação entre o Gene da Sucrase-Isomaltase (SI) e Diabetes mellitus tipos 1,2 e gestaqcional

    OpenAIRE

    Josviak, Nalini Drieli

    2012-01-01

    Resumo: A Sucrase - Isomaltase é uma glicoproteína integral de membrana codificada pelo gene Sucrase - Isomaltase ( SI ; 3q25 - q26 ) , exclusivamente expressa nas microvilosidades do intestino delgado e responsável pela digestão terminal de sacarose e amido . Sabe-se que em Diabetes Mellitus há um aumento na atividade de dissacaridases, incluindo a sucrase-isomaltase , mas até agora nenhum estudo de associação foi descrito entre a expressão aumentada e / ou atividade da sucrase - isomaltase ...

  7. Les relations entre les acteurs locaux et le Conseil des bâtiments civils dans la première moitié du XIXe siècle à Bourges, Colmar et Laval.

    OpenAIRE

    Bondon, Anne

    2013-01-01

    Cet article présente les relations complexes entre le Conseil des bâtiments civils et les acteurs locaux (municipalités, architectes) autour de la question des transformations architecturales et urbaines dans la première moitié du XIXe siècle.

  8. OPTIMIZACIÓN DEL MÉTODO DE MICROEXTRACCIÓN EN FASE SÓLIDA ACOPLADA A CROMATOGRAFÍA GASEOSA PARA ANÁLISIS DE METANOL EN AGUA

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    Fidel Granda

    2011-12-01

    Full Text Available Se optimizó la técnica de microextracciónen fase sólida acoplada a cromatografíagaseosa con detector de ionizaciónde flama (HS-SPME/GC-FID por sunombre en inglés para análisis de metanolen agua utilizando diferentes microfibras,una fibra de poliacrilato y una fibrade polidimetilsiloxano y una columnaRTX-5. Las variables evaluadas fuerontiempo de absorción del contaminante enla fibra, volumen libre en el vial, tiempoy temperatura de desorción y efecto dela agitación y presencia de sal en el sistema.De acuerdo con los resultados, eltiempo óptimo de absorción es 15 minutos,el volumen de muestra es 5 mL. Seencontró que existe una íntima relaciónentre la temperatura de desorción y el área del pico cromatográfico, y una correlaciónR2 = 0,99965 para la curva decalibración elaborada en un rango entre0 y 50%, considerando el origen, con unlímite de detección de 0,01% y un límitede cuantificación del 0,04%.

  9. CONTROLE DE SI, DOR E REPRESENTAÇÃO FEMININA ENTRE LUTADORES(AS DE MIXED MARTIAL ARTS (MMA

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    Samuel Oliveira Thomazini

    2008-12-01

    Full Text Available This papers aims to present results of a seven months ethnographic research in three gyms of Mixed Marcial Arts (MAA, focusing the identity construction of the fighters. Observations and interviews were done, as well as pictures and film takes in traing ans competition were also important. The results suggest the existence of bioidentities processes in sense of selfcontrol and rationalization of pain. The representations of the presence of females is quite ambiguous in this universe of masculinity. La investigación se ocupó de tres gimnasios especializados en Mixed Marcial Arts (MAA, analizando rasgos esenciales de la construcción de las identidades de luchadores y luchadoras. Fueran hecahs durante siete meses observaciones participantes (registradas en diario de campo y entrevistas semi-dirigidas. Fotos y filmages de entrenamientos y competiciones fueran también importantes. Los resultados sugieren la presencia de procesos bioidentitários vinculados al control de si mismo, a la racionalización del dolor y, además, representaciones ambiguas sobre la presencia femenina en este universo que es sobretodo masculino. Trata-se de uma pesquisa realizada em três academias especializadas em Mixed Marcial Arts (MMA. Analisa alguns elementos indispensáveis à forja identitária de lutadores(as desta modalidade. A etnografia durou sete meses, oportunidade para combinar uma observação participante (devidamente registrada no diário de notas com a realização de entrevistas semi-estruturadas com os(as atletas. Fotografias e filmagens dos locais de treinamento e de competição foram recursos metodológicos também úteis. Os resultados indicam a existência de processos bioidentitários vinculados ao controle de si e à racionalização da dor, apontando, além disso, para uma representação ambígua em relação à presença feminina em um universo ainda predominantemente masculino.

  10. Entre ville et campagne, la villégiature à Angers (Maine-et-Loire au XIXe siècle

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    Dominique Letellier-d'Espinose

    2009-11-01

    Full Text Available Quelles formes prend au XIXe siècle la villégiature dans les proches abords d’une ville de taille moyenne comme Angers ? Le sujet est particulièrement riche durant cette période de forte urbanisation où s’interpénètrent une campagne de proximité avec son héritage patrimonial et les quartiers suburbains, nouveaux espaces « résidentiels ». La frontière mouvante entre espace rural et urbain, comme la notion floue et évolutive de temporalité qui met à mal la distinction entre résidences permanentes et temporaires, rejoint les désirs de nature du citadin ou de confort moderne du châtelain bien analysés par le théoricien Daly. Ce phénomène sociétal se traduit par des expressions architecturales souvent ambivalentes, que différencie surtout la relation au lieu. Du front urbain au chemin rural, du jardin paysager miniature au parc domanial, le paramètre contextuel est évidemment déterminant dans l’appréhension d’une villégiature de bord de ville.What are the forms of countryside retreat during the nineteenth century in the immediate vicinity of a medium-sized town such as Angers? The subject is a remarkably stimulating one during this period which saw the expansion of the town into the surrounding countryside where an existing heritage of country houses was now joined by new ‘residential’ spaces of suburban neighbourhoods. The fluctuating frontier between urban and rural space, along with evolving notions of the occupation of time, making the distinction between a permanent and a holiday residence uncertain, find an echo in the theories of Daly about the town-based desires for modern comfort shared by the class of country house owners. The societal phenomenon finds expression in architectural terms which is often ambivalent, producing differences in relation to specific places. From the urban street front to the rural lane, from the miniature landscaped garden to the estate park, contextual parameters are

  11. Les réseaux économiques dans le secteur de la mode vestimentaire à Shanghai entre la fin du XIXe siècle et les années 1930

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    Brasó-Broggi, Carles

    2015-01-01

    L’industrie de la mode à Shanghai s’est développée entre les dernières décennies du XIXe siècle et les années 1930, et a joué un rôle important dans l’industrialisation du pays. Cet article tente de définir la relation entre la production et la consommation dans l’industrie textile de Shanghai. Une des caractéristiques de la mode est sa capacité à innover en créant de nouvelles tendances distinctes tout en absorbant différentes influences et la mode shanghaïenne au début du XXe siècle était u...

  12. Modelación acoplada de aguas superficiales y subterráneas para la gestión conjunta del recurso hídrico.

    OpenAIRE

    Estrada Restrepo, Óscar Andrés; Vélez Upegui, Jaime Ignacio; Restrepo Tamayo, Carlos Augusto; Vélez Otálvaro, María Victoria

    2010-01-01

    Se presenta una metodología de modelación acoplada de aguas superficiales y subterráneas a partir de la integración de un modelo de flujo subterráneo (MODFLOW) con un modelo hidrológico que permite estimar la producción de escorrentía superficial y la recarga de los acuíferos, para tener una aproximación cuantitativa de la interacción río-acuífero y que sirva como herramienta de apoyo para tomar decisiones en la gestión del uso conjunto de aguas superficiales y subterráneas.

  13. Le réformateur, le prince et l’infidèle, entre Aragon et Silésie (XIVe-XVe siècles

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    Ludovic Viallet

    2010-06-01

    Full Text Available A partire dal libro di Paolo Evangelisti, l'Autore si sofferma, nell'ambito del contributo dato dai Francescani alla costruzione dello Stato, sulla questione degli usi del "paradigma" Passio Christi e corpo mistico, della riforma, per quanto attiene il controllo sociale e i simboli identitari, e del sacro.

  14. Le réformateur, le prince et l’infidèle, entre Aragon et Silésie (XIVe-XVe siècles)

    OpenAIRE

    Ludovic Viallet (a cura di)

    2010-01-01

    A partire dal libro di Paolo Evangelisti, l'Autore si sofferma, nell'ambito del contributo dato dai Francescani alla costruzione dello Stato, sulla questione degli usi del "paradigma" Passio Christi e corpo mistico, della riforma, per quanto attiene il controllo sociale e i simboli identitari, e del sacro.

  15. Comparison of energy expenditure and closed-loop performance of thermal and reactive distillation sequences coupled for biodiesel production; Comparacion de gasto energetico y desempeno a lazo cerrado de secuencias de destilacion reactiva y termicamente acopladas para produccion de biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Cornejo-Jacob, J.L [Universidad Michoacana de San Nicolas de Hidalgo, Morelia, Michoacan (Mexico); Vazquez-Ojeda, M; Segovia-Hernandez, J.G; Hernandez, S [Universidad de Guanajuato, Guanajuato, Guanajuato (Mexico); Maya-Yescas, R. [Universidad Michoacana de San Nicolas de Hidalgo, Morelia, Michoacan (Mexico)]. E-mail: rmayay@umich.mx

    2013-03-15

    Biodiesel is the common name for fatty acid methyl esters, obtained by esterification (basic catalysis) or trans-esterification (acid catalysis) of vegetable or animal oils with alcohols, and used as liquid fuel. Production involves the reaction, under mild conditions, between the oil and, typically, excess of methanol. Traditional production of biodiesel exhibits some handicaps, such as the shift of equilibrium to fatty acids by using excess of alcohol that must be separated and recycled. As alternative, it is possible to integrate reaction/separation operations into a single intensified unit, a reactive distillation column, followed by a second separation unit. These configurations exhibit several advantages such as shifting equilibrium in the reactive region and, because of the thermal integration with the second unit, energy savings during products separation. In order to design these production sequences taking advantage of steady state knowledge (energy savings) and considering dynamic performance, this work performs a controllability analysis for six possible configurations; open-loop control properties, evaluated by single value decomposition, are probed by implementing PI controllers to the system. The reactive distillation column coupled to a stripper, without reboilers, shows to be the best option in terms of closed-loop performance and energy savings. [Spanish] Biodiesel es el nombre comun dado a metil esteres de acidos grasos obtenidos por esterificacion (catalisis basica) o trans-esterificacion (catalisis acida) de aceites animales o vegetales con alcoholes, y usados como combustibles liquidos. Su produccion involucra la reaccion entre el aceite y, tipicamente, exceso de metanol a condiciones moderadas. La produccion tradicional de biodiesel exhibe algunas desventajas como el desplazamiento del equilibrio hacia acidos grasos debido al exceso de alcohol, que debe ser separado y reciclado. Alternativamente, es posible integrar las operaciones reaccion

  16. Le diplomate vénitien entre les XVIe et XVIIIe siècles : statut, rôles et fonctions

    OpenAIRE

    Antonio TRAMPUS

    2013-01-01

    Le but de cet article est de présenter la figure du diplomate vénitien, ses caractéristiques et ses fonctions, pour comprendre dans quelle mesure et pourquoi ces ambassadeurs sont devenus un modèle pour les Etats européens. Le modèle théorique de la diplomatie vénitienne aux XVIIe et XVIIIe siècles est comparé avec son fonctionnement pratique dans le cadre de la politique de neutralité et du déclin économique de la République. La description du cas de Venise offre des preuves pour une relectu...

  17. Art et autoreprésentation : la figure du pape entre le xie et le xive siècle

    OpenAIRE

    Paravicini Bagliani, Agostino

    2013-01-01

    Les études de ces dernières décennies ont montré que les papes des xie au xiiie siècles ont élaboré une autoreprésentation très riche en recourant à une créativité métaphorique, symbolique et rituelle qui a placé au centre de l’attention le corps du pape lui-même. Les études sur le mécénat artistique ont mis en évidence la place centrale de la Rome pontificale dans le panorama artistique européen, grâce à la présence d’artistes tels que Pietro Cavallini, Jacopo Torriti et Arnolfo di Cambio. I...

  18. Via Lyon: Parcours de romans et mutations éditoriales au XVIe siècle. Partie II. La circulation des textes entre Lyon et Paris

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    Gaëlle Burg

    2015-07-01

    Full Text Available La première partie du dossier Via Lyon (Carte Romanze 2/2 [2014] analysait le rôle de carrefour économique et culturel de la ville de Lyon dans la constitution d’une identité éditoriale des romans publiés en France au XVIe siècle. L’étude de ces «parcours de romans» conduit à replacer, en cette seconde partie du dossier, la notion d’«étape lyonnaise» dans la dynamique qui anime les deux principaux centres d’imprimerie français de la Renaissance. L’étude des pérégrinations éditoriales, de Paris à Lyon et de Lyon à Paris, de Lancelot du Lac (G. Burg, de Valentin et Orson (M. Colombo Timelli et de Méliadus chevalier de la Croix (A. Réach-Ngô met ainsi au jour les diverses formes de circulation, d’adaptation et de réappropriation que les ateliers parisiens et lyonnais confèrent aux œuvres romanesques qui passent sous leurs presses tout au long du siècle. The first part of the file Via Lyon (Carte Romanze 2/2 [2014] analyzed the role of economic and cultural crossroad of Lyon city in the constitution of an editorial identity of novels published in France in the sixteenth century. The study of these «novels’ route» leads to situate the concept of «Lyon step» in the dynamics which animates the two major French printing centers of the Renaissance. The editorial peregrinations, from Paris to Lyon and from Lyon to Paris, of three french novels, Lancelot du Lac (G. Burg, Valentin and Orson (M. Colombo Timelli and Méliadus chevalier de la Croix (A. Réach-Ngô, shows the various forms of circulation, adaptation and reappropriation that various Parisian and Lyon workshops give to novels they print throughout the century. 

  19. La patria criolla entre localisme exacerbé et solidarité continentale dans la vice-royauté de Lima au XVIIe siècle

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    Bernard Lavallé

    2012-01-01

    Full Text Available Cet article montre comment le créolisme andin du XVIIe siècle fonctionnait et s’affirmait notamment par rapport à une relation très forte à son environnement immédiat, la patria, d’où sa forte coloration localiste et la faible présence dans son discours, voire l'absence, de référents géographiques plus vastes. Il lui était cependant possible d’élargir son regard, et lorsqu’il devait faire face en Espagne aux préjugés péninsulaires, il pouvait aussi faire preuve d'une conscience américaine continentale.Este artículo muestra como el criollismo andino del siglo XVII funcionaba y se afirmaba a partir de une relación muy fuerte con su entorno inmediato, la patria. De ahí su fuerte coloración localista y la escasa presencia, o la ausencia, en su discurso de referentes geográficos más amplios. Sin embargo le era posible ensanchar su mirada, y cuando tenía que enfrentarse en España con los prejuicios peninsulares podía también manifestar una conciencia continental.

  20. Le corps entre sacré et profane : la réforme des pratiques pèlerines en Égypte (xixe-xxe siècles

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    Catherine Mayeur-Jaouen

    2006-11-01

    Full Text Available Les pèlerinages annuels aux tombes des saints, les mouleds, sont l’un des phénomènes saillants de la culture religieuse égyptienne, aussi bien pour les coptes que pour les musulmans. Nés à la fin de l’époque mamelouke, les mouleds n’ont été décrits soigneusement que par leurs détracteurs, notamment les réformistes musulmans de la fin du xixe siècle et de l’entre-deux-guerres, ou par les voyageurs européens du xixe siècle, épris de pittoresque et de scandale. Tous s’entendent pour relever ou dénoncer l’exaltation du corps qu’entraînent les mouleds, et pour relever le “mélange de sacré et de profane” qui caractérise ces fêtes et où le corps est le véhicule principal du sacré. Ce qui choque, c’est de voir les pèlerins associer les dévotions à la danse, les prières à la fête foraine, l’élan vers Dieu à la pantomime obscène, le pèlerinage aux satisfactions du corps dans ses besoins les plus triviaux, le miracle à la prostitution.Les efforts conjugués de l’État égyptien et des clercs musulmans réformistes se sont donc employés, depuis la fin du xixe siècle, à “spiritualiser” les pèlerinages. Les tenants du Renouveau copte, plus récemment mais encore plus efficacement, se sont joints aux musulmans pour “épurer” les mouleds. Chez les coptes comme chez les musulmans, distinguer profane et sacré revient à séparer corps et âme. Le refus de la culture folklorique où s’ancraient les usages pèlerins du corps est devenu le discours officiel : il renvoie à une conception sécularisée du sacré où le corps n’a plus sa place.

  1. Relation entre l’environnement politique et économique et la production architecturale dans la ville de Dubrovnik aux XVIIème et XVIIIème siècles

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    Anita Ruso

    2014-06-01

    Full Text Available Durant les debuts dé la période moderne, Dubrovnik (Ragusa en latine, une ville entre l'Orient et l'Occident, fonda sa richesse sur le commerce. Malgré sa position géographique favorable, la ville se situe dans une zone sismique complexe. Le grand séisme qui ravagea Raguse en 1667 tua environ 2000 de ses habitants et détruisit un grand nombre de bâtiments. Cet article porte sur les relations entre la production artistique et l’environnement économique dans la ville de Dubrovnik après le grand séisme qui fournit l’occasion de procéder à une rénovation architecturale de grand envergure. Jusqu'à présent, la vaste bibliographie pourtant sur ce sujet n’a pas encore mis l'accent sur ce rapport. La question se pose de savoir combien et comment furent payés les architectes qu’y vénèrent à l’instigation d'ambassadeurs et d'agents commerciaux ragusain. En outre l’article cherche à éclairer la situation économique de Dubrovnik à partir du milieu du 17ème jusqu'au début du 18ème siècle.   During the Early Modern period, Dubrovnik (Latin Ragusa managed to benefit from its geographical position between the East and the West, making trade the base of its wealth.  Unfortunately, the city was also in the zone subject to seismic activity, and the strong earthquake that struck the city in 1667 killed around 2000 people and physically damaged most of its architecture. Therefore, this article discusses the relationship between artistic production and the economic environment in the city of Dubrovnik after 1667. The consequences of the so called “Great Earthquake” have been partially investigated in terms of importation of architectural projects and architects, but there is no scholarly work on the economy of rebuilding of the city on the periphery of catholic Europe. The article includes a list of repaired and rebuilt architecture as well as information about the payments for it and the general economic situation in

  2. Correlação entre permeabilidade e resistência mecânica de filtros cerâmicos no sistema Al2O3-SiC Relationship between permeability and mechanical strength of Al2O3-SiC ceramic filters

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    V. R. Salvini

    2000-06-01

    Full Text Available Tem sido crescente o uso de cerâmicas reticulares em processos de refino e purificação de metais fundidos, filtração de gases quentes e combustão catalítica. A aplicação depende da composição química e das propriedades físicas do material (número de poros por polegada linear (ppi, porosidade e diâmetro de poro. Há um consenso de que a melhoria das propriedades dos filamentos resulta em um melhor desempenho mecânico do filtro cerâmico. Entretanto, a análise dos valores de resistência mecânica não pode ser considerada isoladamente, uma vez que para filtros cerâmicos esta tem que estar associada à permeabilidade. Neste trabalho é feita uma análise entre as propriedades fluidodinâmicas e mecânicas de filtros cerâmicos no sistema Al2O3-SiC na faixa de 8 a 90 ppi. Os resultados obtidos permitem considerações tanto no aspecto do processamento cerâmico quanto no modelamento mecânico apresentado na literatura.Reticulate ceramics have been increasingly employed in purification of gases, liquid metals and in catalytic processes. The application area usually depends on the chemical composition and the physical properties (porosity, pore size and pore counting (ppi. In most cases, reticulate ceramics are submitted to compression loads at high temperatures, which makes the durability of these cellular materials be ultimately related to the mechanical quality of the struts. In filtration applications, it is also important the evaluation of fluid dynamic properties of the ceramic, specifically its permeability to fluid flow. In this work, a relationship between mechanical properties and permeability constants of Al2O3-SiC ceramic foam filters with 8 to 90 ppi is presented. Results were associated with the processing technique and with the mechanical modeling presented in the literature.

  3. Scènes de plage dans la peinture hollandaise du XVIIe siècle: l'entrée de la plage dans l'espace des citadins

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    Rémy Knafou

    2000-06-01

    Full Text Available Les scènes de plage sont une catégorie de la peinture hollandaise, inventée au XVIIe siècle. L'analyse d'un corpus de tableaux peints durant le Siècle d’Or permet de montrer que le «désir de rivage» analysé par Alain Corbin est apparu sur le littoral de la mer du Nord dès le XVIIe siècle avec l'ouverture de la plage aux citadins oisifs venus des villes voisines.

  4. Correlations between thermogravimetric analysis and gas chromatography techniques with mass spectrometry in fuels analysis; Correlacao entre as tecnicas termogravimetrica e cromatografia gasosa acoplada a espectrometria de massas na analise de combustiveis

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, Marcelo Marques da; Yoshida, Maria Irene; Fortes, Isabel Cristina Pereira [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Quimica]. E-mail: mmfon@terra.com.br; mirene@dedalus.lcc.ufmg.br; fortesic@dedalus.lcc.ufmg.br

    2003-07-01

    Gasoline is a complex mixture of paraffinic, naphtenic, olefinic and aromatic hydrocarbons, whose ebullition strip varies of 30 to 220 deg C. Its composition is function of the types of processes used for its production. The increase of the consumption of this fuel requests larger control to guarantee the quality and safety of the population that it is committed for the adulteration by solvent addition. Monitoring of the quality of the gasoline is made, mainly, for the distillation - ASTM D86. This work has as objective to evaluate the thermal behavior of the gasoline automotive, type C(with and without adulteration) by Thermal analysis (TG, DTG) and to got parameters that allow to certify the adulteration for comparison with the standard curve. Beyond that samples were analyzed by CG/EM seeking a correlation among both . Samples were prepared for addition of 22% of alcohol ethyl anhydrous to reference gasoline produced by the Gabriel Passos Refinery (REGAP) and adulterated with solvents of several natures. TG curves were obtained in equipment model SHIMADZU-TGA- 50H .Chromatographic features and their respective mass spectra were obtained in the equipment CG/MSQP5050 of Shimadzu. The observation of the data experimental exhibition a displacement of the TG curve in relation to the standard sample. Variation happens in function of the type of mixture of solvents used in the adulteration and of the amount added to the fuel. (author)

  5. Entre la vigne et la croix. Dionysos dans les discours littéraires et figurés chrétiens (iie-ive siècles)1

    OpenAIRE

    Massa, Francesco

    2013-01-01

    Mon doctorat est consacré à l'analyse du rôle du dieu grec Dionysos dans la production littéraire et figurée chrétienne des premiers siècles de l'époque impériale romaine (iie-ive siècles). La recherche s'inscrit dans deux courants d'études principaux : le premier renouvelle l'analyse des contacts religieux pendant les premiers siècles de notre ère, en proposant d'éclairer comment les situations de contact interviennent dans la formation et la définition des identités religieuses ; le deuxièm...

  6. (E-2-Nonenal determination in brazilian beers using headspace solid-phase microextraction and gas chromatographic coupled mass spectrometry (HS-SPME-GC-MS Determinação de (E-2-nonenal em cervejas brasileiras utilizando microextração em fase sólida do headspace e cromatografia gasosa acoplada a espectrometria de massas

    Directory of Open Access Journals (Sweden)

    Rodrigo Scherer

    2010-05-01

    Full Text Available (E-2-nonenal is considered an important off-flavor of beer, related to the flavor of beer staling. In this study, a new method for determination of (E-2-nonenal in beer using headspace solid-phase microextraction and gas chromatographic coupled mass spectrometry (HS-SPME-GC-MS was developed and applied in Brazilian beer samples. The extractions were carried out in CAR-PDMS (carboxen-polydimethylsiloxane fiber and the best results were found with 15 minutes of equilibrium and 90 minutes of extraction at 50 °C. The method was linear in the range from 0.02 to 4.0 μg.L-1 with correlation coefficient of 0.9994. The limits of detection and quantification were 0.01 and 0.02 μg.L-1, respectively. 96.5% of recovery and 4% precision (RSD were obtained in the fortification of beer samples with 2.0 μg.L-1 of (E-2-nonenal. The developed method proved to be simple, efficient and highly sensitive to the determination of this analyte being easily applied in the quality control of the brewery. (E-2-nonenal was found in all beer samples analyzed with levels between 0.17 and 0.42 μg.L-1.O (E-2-nonenal é considerado um importante off-flavor da cerveja, sendo relacionado ao sabor de cerveja envelhecida. Neste estudo, um novo método para determinação de (E-2-nonenal em cerveja usando microextração em fase sólida do headspace e cromatografia a gás acoplada à espectrometria de massa (HS-SPME-GC-MS foi desenvolvido e aplicado em amostras de cerveja brasileira. As extrações foram realizadas utilizando a fibra CAR/PDMS (carboxen/polidimetilsiloxano, com 15 minutos de tempo de equilíbrio e 90 minutos de exposição da fibra a 50 °C. O método foi linear na faixa de 0,02 e 4,0 μg.L-1, com coeficiente de correlação de 0,9994. Os limites de detecção e quantificação foram 0,01 e 0,02 μg.L-1, respectivamente. Foram obtidos 96,5% de recuperação e 4% de variação entre replicatas de amostras de cerveja fortificadas com 2,0 μg.L-1 de (E-2-nonenal. O m

  7. Transferts culturels entre l'Allemagne et la France dans le domaine de la musique instrumentale au XIXe siècle : La musique à programme et l'influence allemande en France. 1870-1914

    OpenAIRE

    Ehrhardt, Damien

    2004-01-01

    The works presented in my habilitation file are concerning different aspects of 19th Century German and French instrumental music : the works of Schumann , the typology of variation form, the Riemannian theory and program music . The subject of the unpublished memorandum is: "The program music and the German influence in France 1870-1914 "; Les travaux présentés dans mon dossier d'HDR concernant différents aspects des musiques instrumentales allemand et française du XIXe siècle: les oeuvres d...

  8. Aude Mairey, Une Angleterre entre rêve et réalité. Littérature et société dans l’Angleterre du 14e siècle

    OpenAIRE

    Doudet, Estelle

    2008-01-01

    Depuis une trentaine d’années, les études inspirées par le New Historicism ont fait évoluer le statut des textes littéraires dans la recherche historique. D’objets marginaux, ils sont devenus de véritables sources. Par un mouvement complémentaire, la Nouvelle Philologie a orienté plus résolument les études littéraires vers le couple désormais indissociable « texte/contexte ». L’historienne Aude Mairey propose ici une étude socio-culturelle de l’Angleterre au 14e siècle. On sait qu’outre les t...

  9. Pratiques de l’espace hospitalier par les religieuses au XIXe siècle dans les hôpitaux parisiens : préserver un entre-soi religieux et féminin ?

    OpenAIRE

    Jusseaume, Anne

    2016-01-01

    Au XIXe siècle, les sœurs hospitalières, bien que théoriquement séparées du monde et disposant d’espaces et de temps propres à leur vie religieuse, sont pourtant quotidiennement au contact d’ecclésiastiques, d’hommes et de femmes laïques qu’ils soient malades ou personnels hospitaliers. Il ne s’agit pas ici de questionner la clôture avec le monde extérieur, ou l’enfermement des sœurs et des malades au sein des hôpitaux, déjà abordés par l’historiographie, mais plutôt de déplacer le regard ver...

  10. Entre itinéraires et trajets : représentations des déplacements dans les guides de voyage au tournant du XIXe siècle

    Directory of Open Access Journals (Sweden)

    Ariane Devanthéry

    2011-06-01

    Full Text Available Un itinéraire est plus qu’une route : c’est une route sélectionnée, choisie par une époque et jalonnée de savoirs, de devoirs et d’émotions. Le Grand Tour ayant connu des itinéraires fortement codés, comment se fait le passage au tourisme ? En douceur ou avec fracas ? Y a-t-il alors abandon de tout itinéraire, invention de nouveaux cheminements ou redéfinition ? Et si la transformation du Grand Tour en tourisme se jouait aussi dans les manières de mettre en scène l’espace des voyages ?An itinerary is more than a route: it is a selected route, chosen by a time and lined with knowledge and emotions. As the Grand Tour had known some strongly coded itineraries, how does the transition to tourism happen? Smoothly or with a crash? Is then a giving up of all itineraries, new ways invented, or redefinition? And what if the Grand Tour converting into tourism was also been acted in the way of displaying the travelling space?

  11. L’irresponsabilité pénale dans la première moitié du XIXe siècle, entre classicisme et défense sociale

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    Laurence Guignard

    2005-07-01

    Full Text Available Nous tentons de saisir, dans cet article, l’évolution de la doctrine pénale du xixe siècle concernant la question de l’irresponsabilité des déments exprimée dans l’article 64 du code pénal. La doctrine, initialement fondée sur la théorie classique d’un sujet doté d’une volonté libre, qui impose des peines fixes à fonction principalement rétributive, voit émerger progressivement une conception graduée de la responsabilité dont la mesure se fait en fonction de la santé mentale des accusés. Ce nouveau système suppose la mise en place de peines individualisées dans le cadre d’une justice dont la protection de la société est le premier souci. Dans ce processus, les doctrines libérales des néoclassiques ont joué un rôle clef.This abstract deals with the transformation of the penal doctrine during the xixth century. The question of irresponsiblity of the insane contained in the article 64 of the penal code changed during this periode from retributive justice to preventive justice. At the beginning of the century, the legal anthropology of the penal Code of 1810 is founded on the classical theory of a subject with free will. In consequence, no possibility for gradual punishment existed. Progressively, we see emerging a conception of graduated responsability which is a function of the mental sanity of the accused. This new penal system takes place within a legal frame that aimes primarily to protect the society. In this process, liberal neoclassical doctrines play a major role.

  12. Entre exotisme et nostalgie

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    Caroline Rozenholc

    2008-03-01

    agglomération et à promouvoir l’identité globalisée de la ville ? Pour répondre à cette question, et pour contribuer à celle plus vaste de l’attachement au lieu dans la mondialisation, Florentin sert d’ancrage à une réflexion sur le quartier qui permet d’alimenter, entretiens et observations à l’appui, le débat entre tenants de l’hyper-mobilité et des nons-lieux et ceux d’une territorialité au fondement de la géographie et de l’urbanité. Florentin, espace complexe et stimulant, et dont on peut multiplier les « entrées », semble alors indiquer une troisième voie ; celle d’un lieu défini et ouvert où s’articulent, sans s’effacer, des temporalités et des perceptions du lieu distincts et propres, même si parfois partagées, à chacun.Florentin between exoticism and nostalgia.Globalization of an 'authentic' neighborhoodAt the beginning of the 90s, the Municipality of Tel-Aviv, approached by a small group of inhabitants of Florentin neighborhood, decides to invest in it. Florentin, at the time, is one of the poorest areas of the city and alike the whole South of Tel-Aviv, it is in an advanced state of deterioration. Over the last twenty years, buildings had fallen apart and all the population who had opportunities to leave the neighborhood found better dwellings. At the time, the potential of the neighborhood is nevertheless clear to the authorities – due to its peculiar architecture and the interesting mixture of residential and commercial activities – and the successful rehabilitations of both Neve Tseddek (the first Jewish neighborhood out the walls of the ancient Jaffa and Sheinkin street (today a very hype place to hang out stimulate the Municipality to “put Florentin back on the map”. This is a radical step as for few decades Florentin remained very much at the margins of the city, in between Tel-Aviv and Jaffa, only loosing population and gaining in polluting activities, such as small industries and manufactures. After few

  13. La communication entre parents migrants et enseignants

    OpenAIRE

    Frei, Nathalie; Schertenleib, Georges-Alain

    2014-01-01

    La communication entre l’école et la famille semble être une composante essentielle (parmi tant d’autres d’ailleurs !) qui permettrait à l’enfant d’apprendre et d’évoluer sereinement. Elle n’est pourtant pas toujours bien vécue de part et d’autre car il arrive que certains malentendus surviennent. En effet, les enseignants de nos jours ont des contacts avec des familles d’origines très variées et doivent savoir faire preuve d’adaptation face à cette diversité. Même si la tâche est quelques fo...

  14. Interacciones entre plantas y microorganismos del suelo: Consecuencias para la dinámica de comunidades vegetales

    OpenAIRE

    Lozano Bernal, Yudi M.

    2014-01-01

    En esta tesis doctoral pretendemos aclarar aspectos fundamentales relacionados con la interacción entre plantas y microorganismos del suelo y sus consecuencias para la dinámica de las comunidades vegetales. Pretendemos comprobar si las comunidades microbianas están determinando interacciones negativas y/o positivas entre plantas; si tras el abandono de tierras dedicadas al cultivo, las plantas y los microorganismos del suelo siguen patrones sucesionales, y si los microorganismo...

  15. Burnout entre audiologistas

    OpenAIRE

    Ferreira, Ana Luísa Simões Marques

    2015-01-01

    A escassez de recursos e a pressão das instituições para obter resultados estão a levar cada vez mais profissionais ao esgotamento físico e emocional. Um estudo da OCDE, evidência a ligação entre problemas psicológicos e condições de trabalho em 15% a 20% da população ativa. Portugal ocupa o sétimo pior lugar, entre os 34 países pertencentes a esta organização. O burnout é a fase final de uma situação de stresse profissional crónico, apresentando o seu foco principal na exaustã...

  16. Percepções sobre cuidar de si, promoção da saúde e sobrepeso entre acadêmicos de enfermagem Percepciones sobre el cuidado de si mismo, promoción de la salud y sobrepeso en estudiantes de enfermería Perceptions of Self-care, health promotion and overweight among nursing students

    Directory of Open Access Journals (Sweden)

    Luciara Fabiane Sebold

    2011-09-01

    Full Text Available Pesquisa qualitativa, Convergente Assistencial (PCA, desenvolvida com 42 acadêmicos de enfermagem, em uma Universidade Pública da Região Sul do Brasil. Objetivou identificar as percepções dos acadêmicos de enfermagem sobre o cuidar de si, para a promoção da saúde e a evitabilidade do sobrepeso. A coleta dos dados deu-se durante quatro encontros, através de dinâmicas de grupo, confecções de cartazes, atividades lúdicas, utilização de instrumento. A análise dos dados seguiu PCA. Categorias: Atividades físicas; Alimentação saudável; Ambiente familiar; Autoestima e autoimagem. Resultados: Os acadêmicos reconhecem a importância de Cuidar de Si; apresentam conhecimento e relacionam à temática; percebem o Cuidar de Si como forma de manter peso e/ou buscar peso adequado. As contribuições estão no sentido de novas reflexões sobre a realidade dos acadêmicos, e subsídios para inovação do ensino e aprendizagem, sensibilização dos futuros profissionais da área.Investigación cualitativa, Convergente Asistencial (PCA, desarrollada con 42 estudiantes de enfermería en una universidad pública en el sur de Brasil. El objetivo fue identificar las percepciones de los estudiantes de enfermería sobre el cuidado consigo mismo, para promover la salud y prevenir el sobrepeso. La recopilación de datos tuvo lugar durante cuatro sesiones: a través de dinámicas de grupo, de la producción de carteles, de actividades lúdicas, del uso de instrumentos. El análisis de datos siguió PCA. Categorías: actividades físicas, alimentación saludable, ambiente familiar, autoestima y autoimagen. Resultados: los académicos reconocen la importancia de cuidar de si mismos; presentan conocimientos y los relacionan con el tema; perciben el Cuidar de Si mismo como una manera de mantener el peso y / o buscar un peso adecuado. Las contribuciones son a un nuevo pensamiento sobre la realidad de los estudiantes, y subvenciones para la enseñanza y

  17. Amor entre mulheres

    OpenAIRE

    Costa, Vera de Sá Nogueira Botelho da

    2014-01-01

    Dissertação de Mestrado apresentada ao ISPA - Instituto Universitário A literatura psicanalítica evidencia a falta de estudos sobre o amor na homossexualidade feminina. No âmbito de um estudo qualitativo, esta dissertação pretendeu explorar as relações amorosas de seis mulheres homossexuais, com idades compreendidas entre os 36 e os 53 anos, tendo em conta o desenvolvimento da sua identidade, os seus objectos internos, as suas relações de objecto e as suas identificações. O mét...

  18. Entre monos y centauros

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    Serge Gruzinski

    2005-02-01

    Full Text Available    ¿Qué relación puede existir entre Ovidio, Tiziano y unos tlacuilo indios de la sierra otomí ? ¿Qué tienen en comun  el pintor mas famoso del siglo XVI , el veneciano Tiziano (+ 1576,  un poeta latino del primer siglo despues de Cristo, Publio Ovidio Nasón (-43/17 ,  y unos artistas indígenas anónimos del pueblo otomi de Ixmiquilpan?   Aunque la reunión de estos tres nombres parezca extraña y sorprendente, los hilos que los unen no son nada anecdóticos.  Permiten entender mejor la manera...

  19. Relaciones entre la Inteligencia Emocional y el Bienestar en estudiantes universitarios: Diferencias entre titulaciones

    OpenAIRE

    Fraile Diego, Elena

    2014-01-01

    La presente investigación tiene como objetivo analizar la relación entre Inteligencia Emocional y Bienestar en una muestra del alumnado universitario compuesta por 168 participantes de cuatro titulaciones diferentes. Y analizar si existen diferencias en estas variables en función de la titulación y el sexo. Recogimos datos sociodemográficos y evaluamos: a) Inteligencia Emocional con la escala rasgo de metaconocimiento (TMMS-24), b) Bienestar y sus diferentes elementos con la escala de Bienest...

  20. Detecção de resíduos de enrofloxacina por ensaio imunoenzimático e cromatografia líquida acoplada à espectrometria de massas em ovos comerciais de galinha após tratamento

    Directory of Open Access Journals (Sweden)

    R. Gouvêa

    2014-12-01

    Full Text Available A enrofloxacina é um dos antimicrobianos mais utilizados na avicultura industrial, e a deposição de resíduos em produtos avícolas, como os ovos, são de grande importância para a saúde pública. Na legislação brasileira não existe padronização do período de carência para o seu uso na produção avícola e não há Limite Máximo de Resíduo (LMR fixado para enrofloxacina em ovos. Neste estudo, foi utilizado o kit de ELISA comercial (Bioo Scientific(r e a LC-MS/MS na pesquisa de enrofloxacina em ovos de 30 galinhas tratadas previamente via água de bebida, com 10mg/kg de enrofloxacina, durante cinco dias. Seis ovos foram coletados diariamente e analisados durante o tratamento e após a sua suspensão, durante 15 dias. A deposição de resíduos obteve níveis máximos no quinto dia de tratamento das aves, declinando gradativamente até não ser detectada a partir do nono dia de suspensão do tratamento. Considerando como base o LMR de 100µg/kg fixado pelo Brasil para tecidos comestíveis de aves e pela União Europeia para músculo, gordura e pele, após seis dias de suspensão do tratamento, os níveis de resíduos foram inferiores a esse limite, tendo como médias 37,43µg/kg na LC-MS/MS e 14,731µg/kg no ELISA. Dentro das condições deste estudo, um período de carência de seis dias seria mais adequado para utilização dos ovos para consumo humano. Foram detectados valores de resíduos nos ovos menores no ELISA em relação à LC-MS/MS para a mesma amostra, mas os dois métodos apresentaram concordância estatística entre si. A LC-MS/MS é o teste recomendado pela legislação brasileira para a análise de resíduos em alimentos; entretanto, pelos resultados obtidos, o kit de ELISA utilizado também pode ser aplicado na detecção de resíduos de enrofloxacina em ovos, com as vantagens de rapidez e simplicidade.

  1. Espectros biológicos florísticos de Campos Rupestres de afloramento e Campos Úmidos diferem entre si e em relação ao Espectro Biológico Normal de Raunkiaer. Floristic biological spectra of Rock outcrops and Wet grasslands differ between themselves and in relation to the Raunkiaer’s Normal Biological Spectrum.

    Directory of Open Access Journals (Sweden)

    Natalia de Oliveira COSTA

    2012-12-01

    Full Text Available A distribuição de frequência de classes de formas de vida em uma flora, conhecida como espectro biológico florístico, varia em função das condições climáticas e edáficas em que as plantas se desenvolvem. Neste trabalho comparamos os espectros biológicos médios (n = 3 de equivalentes a Campo Rupestre de afloramento e a Campo Úmido no Estado de São Paulo na expectativa de encontrar diferenças significativas entre os dois tipos de comunidade. Os Campos Rupestres (G-corrigido = 23,41; p-valor = 0,0001 e os Campos Úmidos (G-corrigido = 80,34; p < 0,0001 diferiram do Espectro Biológico Normal de Raunkiaer, bem como diferenciaram-se entre si (χ2 = 24,23; p < 0,0001. Uma Análise de Correspondência Distendida separou Campos Rupestres de Campos Úmidos devido às maiores frequências de fanerófitos nos primeiros e de hemicriptófitos e terófitos nos últimos. Sugerimos como hipóteses que os micro-habitats favoráveis ao desenvolvimentode fanerófitos sejam mais comuns nos Campos Rupestres de afloramento do que nos Campos Úmidos, ocorrendo o contrário com os micro-habitats favoráveis aos hemicriptófitos. Esta forma de vida pode apresentar melhor ajustamento ao encharcamento do solo do que os caméfitos e geófitos. A estratégia de escape apresentada pelos terófitos seria pouco eficiente em Campos Rupestres de afloramento devido à escassez de solo para proteção das sementes. The frequency distribution of life forms in a flora, called floristic biological spectrum, varies according to the climatic and edaphic conditions under which plants grow. In this work we compared the average (n = 3 biological spectra of Rock outcrop and Wet grassland like communities in São Paulo state expecting to find significant differences between the two community types. Rock outcrops (G-corrected = 23.41; p-value = 0.0001 and Wet grasslands (G-corrected = 80.34; p < 0.0001 differed from the Raunkiaer’s Normal Biological Spectrum, as did between

  2. Pour un dialogue mondial entre traditions philosophiques

    OpenAIRE

    Dussel, Enrique

    2013-01-01

    Nous allons essayer de réfléchir à un sujet qui, je crois, occupera une bonne partie du xxie siècle : l’acceptation par chacune des traditions régionales philosophiques de la planète (européenne, nord-américaine, chinoise, hindoue, arabe, africaine, latino-américaine, etc.) du sens, de la valeur et de l’histoire de chacune d’entre elles. Pour la première fois dans l’histoire de la philosophie, différentes traditions entameraient un dialogue authentique et symétrique grâce auquel elles découvr...

  3. ????????????-???????????? ?????? ? ????????????? ????????? ???????? ??????? Ge-Si

    OpenAIRE

    ????????, ?. ?.; ???????????, ?. ?.; ???, ?. ?.; ?????????, ?. ?.

    2003-01-01

    ?????????? ????????????-???????????? ?????? ? ????????????? ????????? (??) ???????? ??????? GexSi1-x (? = 0.01 - 0.03) p-???? ??????????? ? ?????????????? ????????? (4,2 ... 300 K). ????????????? ????? ?????????? ?? ?????-??? ?? ?????????????????? ??. ??????????? ?????????? ??????? ????????? ??????? ??? ?????????? ??. ???????? ?????????? ??????????? ?'???-??????? ?? ??????????????? ? ?? Ge-Si ??????? ???????? ?????-?????????? ?? ???????? ???????????. ?????????? ?????????? ??????????? ???...

  4. Communication entre deux mondes: relations amicales entre sourds et entendants

    OpenAIRE

    Favre, Cynthia; Pitarelli, Emilio

    2008-01-01

    Ce travail de recherche aborde la problématique de la surdité. Il souhaite étudier plus particulièrement les relations entre personnes sourdes et entendantes. Il permet de bousculer certaines fausses conceptions concernant les personnes sourdes et donne des informations au sujet de leur histoire, de leur mode de vie et de leur communauté. Cette recherche recense également les facteurs qui peuvent influencer la communication ainsi que les relations amicales entre les personnes sourdes et enten...

  5. Generación de materia orgánica acoplada a la eliminación de CO2 por Anabaena sp. ATCC 33047 y su utilización para la remoción de cadmio

    OpenAIRE

    Esteban Clares, Marta

    2011-01-01

    El incremento del nivel atmosférico de dióxido de carbono, gas de efecto invernadero, y la necesidad de reducir el mismo constituye un problema global de ingentes proporciones. Una aproximación a este problema consiste en la utilización de microorganismos fotosintéticos para la retirada del CO2. Microalgas y cianobacterias se encuentran entre los más efectivos fijadores de CO2 del planeta, con rendimientos considerablemente superiores a los de los cultivos agrícolas más productivos. En este t...

  6. ANÁLISIS DE RESIDUOS DE PLAGUICIDAS EN TOMATE MEDIANTE EL USO DE QuEChERS Y CROMATOGRAFÍA LÍQUIDA ULTRARRÁPIDA ACOPLADA A ESPECTROMETRÍA DE MASAS

    Directory of Open Access Journals (Sweden)

    Diego A. Ahumada

    2011-12-01

    Full Text Available Se desarrolló un método multirresiduopara la determinación de 24 plaguicidasde diferentes características fisicoquímicasen tomate. El proceso de extracciónse basó en el método QuEChERS y la determinaciónde los compuestos se realizómediante cromatografía líquida ultrarrápidaacoplada a espectrometría de masas.Los resultados de la validación indicaronque el método presenta porcentajes derecuperación de entre el 71,3 y el 114%,coeficientes de variación inferiores al20%, límites de detección entre 0,002 y0,225 mg/kg, límites de cuantificaciónentre 0,009 y 0,750 mg/kg. En los estudiosde linealidad, para todos los parámetrosevaluados, se obtuvieron resultados adecuados en los rangos de trabajo. Paraprobar la metodología desarrollada, seevaluaron muestras de frutos de tomateprovenientes del departamento de Boyacáy se halló indoxacarb en cantidadesinferiores al límite máximo de residuos.

  7. Algunas diferencias entre universidades europeas

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    Belén Pascual

    2009-07-01

    Full Text Available Es un breve texto sobre algunas de las diferencias más notables que hay entre nuestra Universidad y las Universidades del Reino Unido. Basadas en la experiencia personal, estas diferencias muestran que los dos sistemas difieren en varios aspectos.

  8. Relación entre Inteligencia Emocional y rendimiento escolar

    OpenAIRE

    Vicente-Pérez, Minerva

    2014-01-01

    Actualmente, la Inteligencia Emocional es un tema de plena actualidad, y es creciente el número de estudios que se publican al respecto. Su influencia en los procesos de enseñanza-aprendizaje y su importancia en el entorno escolar son bien conocidas, sin embargo, aún resulta necesario indagar en el papel de las emociones en el rendimiento académico de los alumnos. El presente estudio trata de comprobar si existe relación entre la Inteligencia Emocional y el rendimiento académico en los alu...

  9. El periodista, entre el Poder

    Directory of Open Access Journals (Sweden)

    JL Dader

    2014-10-01

    Full Text Available El periodismo se debate, desde sus orígenes, entre la reproducción servil de versiones interesadas o la distorsión de propio cuño, por conocimiento insuficiente de una realidad que sólo puede entrever. Los poderes que amenazan la independencia periodística no han hecho más que crecer o aumentar su habilidad con el paso del tiempo. Surgido como ‘oficio de esclavos’ en la época romana, muchos indicadores actuales parecen retornarle al punto de partida: relaciones públicas estratégicas a gran escala, auge de los ‘spin doctors’, extorsión descarnada en las democracias más débiles y populismo de las redes sociales, entre otros. Todo ello, unido o alentado por la degradación interna y el desaliento de la propia institución periodística incapaz de distanciarse de todas esas fuerzas. Su respuesta no puede ser de alianza o competencia con los poderes que la circundan, sino de hábil distanciamiento para moverse entre todos ellos sin dejar de ejercer la vigilancia que los ciudadanos siguen necesitando de su ejercicio profesional.

  10. 与Si工艺兼容的Si/SiGe/Si HBT研究%The Study of Si/SiGe/Si HBT and Its Compatibility with Si Process

    Institute of Scientific and Technical Information of China (English)

    廖小平

    2001-01-01

    我们对Si/SiGe/Si HBT及其Si兼容工艺进行了研究,在研究了一些关键的单项工艺的基础上,提出了五个高速Si/SiGe/Si HBT结构和一个低噪声Si/SiGe/Si HBT结构,并已研制成功台面结构Si/SiGe/Si HBT和低噪声Si/SiGe/Si HBT,为进一步高指标的Si/SiGe/Si HBT的研究建立了基础.

  11. Causalidade entre as principais bolsas de valores do mundo

    Directory of Open Access Journals (Sweden)

    Hiron Pereira Farias

    2010-04-01

    Full Text Available O objetivo deste trabalho foi analisar os mercados dos países emergentes que fazem parte do Bric, com exceção da Índia, buscando mostrar como os mercados do Brasil, da Rússia e China se comportam entre si e em relação ao mercado dos Estados Unidos. Analisou-se também como alguns países desenvolvidos do grupo G8, Estados Unidos, Reino Unido e Japão, se comportam. Em cada análise, ajustou-se um modelo VAR e buscou-se verificar o grau de dependência dentro e entre cada grupo, utilizando teste de causalidade de Granger, critérios de seleção de modelos, função resposta a impulso e decomposição da variância do erro de previsão. Nas análises realizadas, os mercados brasileiro e americano mostraram forte influência sobre os demais mercados, e, na análise entre os grupos, consideraram-se o mercado dos Estados Unidos do grupo ERJ e todos os mercados emergentes do grupo BRC. O mercado americano mostrou forte influência sobre os outros mercados.

  12. La Vocación entre los Aspirantes a Maestro

    Directory of Open Access Journals (Sweden)

    Encarnación Sánchez Lissen

    2003-01-01

    Full Text Available El contenido que ofrecemos en este artículo hace referencia a la dimensión vocacional de los aspirantes a maestro. Tradicionalmente, la enseñanza se ha considerado como una profesión genuinamente vocacional; una circunstancia que, sin embargo, no siempre le ha favorecido. En estos momentos, a pesar de las dificultades que rodean la tarea docente, existe un alto número de estudian-tes que optan por la enseñanza y acceden a las Escuelas de Magisterio. Real-mente, nos podríamos preguntar si el docente -nace o se hace- vocacional hacia esta actividad profesional. Aportamos para ello, los datos de una investigación realizada entre estu-diantes de la Universidad de Sevilla, donde se viene a demostrar por un lado que, muchos eligieron la carrera sin tener un verdadero interés por ella; y por otro, que las Escuelas de Magisterio son en muchos casos, un motor esencial para llegar a despertar o, a descubrir entre los estudiantes, su verdadero interés e inclinación por la enseñanza. Posiblemente, desarrollar actitudes vocaciona-les entre tos aspirantes a maestro es, también, una labor implícita de la Forma-ción Inicial de Maestros

  13. Application of the SPA in the design of a hydrogen producer plant coupled to a nuclear reactor; Aplicacion del APS en el diseno de una planta productora de hidrogeno acoplada a un reactor nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz S, T.; Nelson, P. F.; Francois, J. L. [UNAM, Facultad de Ingenieria, Departamento de Sistemas Energeticos, Paseo Cuauhnahuac No. 8532, Col. Progreso, 62550 Jiutepec, Morelos (Mexico); Cruz G, M. J., E-mail: truizsmx@yahoo.com.mx [UNAM, Facultad de Quimica, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

    2013-10-15

    At the present time, one of the processes that is broadly investigated and that, theoretically demonstrates to be one of the most efficient for the hydrogen production, is the thermal-chemistry cycle Sulfur-Iodine (S-I) coupled to a nuclear reactor of very high temperature (VHTR). Because this chemical process of hydrogen production requires of a great inventory of toxic materials (sulphide compounds, hydriodic acid and iodine), is necessary the design of emergency systems with the purpose of protecting the facilities and the equipment s, the environment, as well as the near population. Given the impact of an accidental liberation of the process materials, as well as the proximity with the nuclear plant, is necessary that these emergency systems are the most reliable possible. This way, the results of the consequences analysis are utilized for the optimal localization of the gas sensors that activate the emergency systems, and the flows of the substances that are used for the leakage control. For all this, the use of the Safety Probabilistic Analysis methodology, as well as some standards of the nuclear industry, can be applied to the chemical installation to determine the fault sequences that can take to final states of not controlled leakage. This way, the use of methodologies of Event Tree Analysis and Fault Trees show in their results the components that but contribute in fault of such systems. In this work, is presented the evaluation of the joined models of event and fault trees and like with the obtained results, some proposals to increase the safety of the facilities are exposed. Also, the results of the evaluations of these proposals, and their impact of the probability of the not controlled fault sequences in a plant that is still in design stage are showed. (Author)

  14. Identificação de compostos orgânicos e farmacêuticos em esgoto hospitalar utilizando cromatografia gasosa acoplada a espectrometria de massa Identification of organic and pharmaceutical compositions in hospital wastewater using a gas chromatograph coupled to mass spectrometry

    Directory of Open Access Journals (Sweden)

    Francisco Vieira Paiva

    2011-03-01

    Full Text Available Os resíduos líquidos provenientes dos estabelecimentos assistenciais de saúde são mais complexos do que os esgotos domésticos. Sua composição contém inúmeros compostos farmacêuticos, saneantes, elementos radiativos e de laboratórios. O conhecimento desses compostos pode auxiliar na escolha do tratamento adequado para esses esgotos e diminuir os impactos ambientais nos corpos receptores. A pesquisa foi realizada utilizando um sistema combinado (UASB e lodos ativados para tratar a água residuária de um hospital. Neste trabalho, foram realizadas análises físico-químicas para caracterização do esgoto e cromatografia gasosa acoplada à espectrometria de massa para identificação de compostos químicos farmacêuticos, podendo-se constatar a presença de inúmeros elementos residuais dos fármacos usados no hospital.Liquid waste residues from health care establishments are more complex than those from residential sewage. Their composition contains several pharmaceutical chemical composites, sanitizers, radioactive, and laboratorial elements. Knowing about these composites may aid in choosing the proper treatment for these sewages, and diminish the environmental impact in receptors. The study was carried out in a combined system (UASB and activated sludge to treat a hospital wastewater. In this experiment, material and chemical analyses were employed to trace sewage characteristics and gas chromatography associated with mass spectrometry to identify pharmacologic chemical composites, where innumerous residual elements were found in chromatographs.

  15. Interface structure between epitaxial NiSi2 and Si

    Institute of Scientific and Technical Information of China (English)

    Wei-Long Liu; Wen-Jauh Chen; Ting-Kan Tsai; Hsun-Heng Tsai; Shu-Huei Hsieh

    2006-01-01

    The interface structure between the Si and NiSi2 epitaxially grown on the ((-1)12) Si substrate was studied using high resolution transmission electron microscopy and computer image simulation. The results showed that the interface between Si and NiSi2 epitaxially grown on the ((-1)12) Si substrate has six different types: type A NiSi2 ((-1)11 )/( (-1)11 ) Si, type A NiSi2 (001)/(001) Si, type B NiSi2 (1(-1)(-1))/(1(-1)1) Si, type B NiSi2 ((-1)12)/(1(-1)2) Si, type B NiSi2 (2(-2)1)/(001) Si, and type B NiSi2 (1(-1)(4))/( 1(-1)0 ) Si. And there are one or more different atomic structures for one type of interface.

  16. 射频 Si/SiGe/Si HBT的研究%Studies on RF Si/SiGe/Si HBT

    Institute of Scientific and Technical Information of China (English)

    廖小平; 殷刚毅

    2003-01-01

    Si/SiGe/Si HBT与Si工艺兼容的研究基础上,对射频Si/SiGe/Si HBT的射频特性和制备工艺进行了研究,分析了与器件结构有关的关键参数寄生电容和寄生电阻与Si/SiGe/Si HBT的特征频率fT和最高振荡频率fmax的关系,成功地制备了fT为2.5 GHz、fmax为2.3 GHz的射频Si/SiGe/Si HBT,为具有更好的射频性能的Si/SiGe/Si HBT的研究建立了基础.

  17. La telecolaboración entre grupos heterogéneos en la clase de lengua extranjera

    OpenAIRE

    López Santiago, Mercedes; Ballez, Michèle

    2014-01-01

    [es] En la enseñanza de lenguas extranjeras, numerosos profesores trabajan las competencias lingüísticas y comunicativas por medio de actividades que incluyen las TIC. Entre ellas, se encuentran los proyectos de telecolaboración por Internet, intercambios asincrónicos y sincrónicos, entre grupos de estudiantes pertenecientes a diferentes comunidades lingüísticas distantes geográficamente. Nuestro objetivo ha consistido en comprobar si un proyecto de telecolaboración sincrónico entre grupos he...

  18. La telecolaboración entre grupos heterogéneos en la clase de lengua extranjera

    OpenAIRE

    López Santiago, Mercedes; Ballez, Michèle

    2014-01-01

    En la enseñanza de lenguas extranjeras, numerosos profesores trabajan las competencias lingüísticas y comunicativas por medio de actividades que incluyen las TIC. Entre ellas, se encuentran los proyectos de telecolaboración por Internet, intercambios asincrónicos y sincrónicos entre grupos de estudiantes pertenecientes a diferentes comunidades  lingüísticas distantes geográficamente. Nuestro objetivo ha consistido en comprobar si un proyecto de telecolaboración sincrónico entre grupos heterog...

  19. A importância das interacções entre fungos do solo em agroecologia

    OpenAIRE

    Baptista, P; Pereira, Eric; Tavares, R. M.; Neto, T. Lino

    2011-01-01

    Os microrganismos vivem no solo sob a forma de comunidades complexas, sendo constantes as interacções que estabelecem entre si e com as raízes das plantas. Esta enorme diversidade de interacções contribui, de forma preponderante, para a fertilidade do solo, desenvolvimento, nutrição e sanidade das plantas. Ao nível da comunidade fúngica do solo é possível observar vários tipos de interacção entre diferentes espécies fúngicas, sendo o antagonismo um dos mais comuns. Os fungos do solo são igual...

  20. Relación entre habilidades de lectura de palabras y comprensión lectora

    OpenAIRE

    Vieiro, Pilar; Amboage, Isabel

    2016-01-01

    La lectura es un aprendizaje instrumental que debe ser enseñado con un método específico. En este sentido es importante conocer la interrelación entre los distintos subprocesos implicados. En este contexto el objetivo general de este estudio es analizar si existe una asociación o disociación entre las habilidades de lectura de palabras y los procesos de comprensión en alumnos de 2º ciclo de Educación Primaria y a partir de aquí analizar las implicaciones educativas de los resultad...

  1. Ordering at Si(111)/o-Si and Si(111)/SiO2 Interfaces

    DEFF Research Database (Denmark)

    Robinson, I. K.; Waskiewicz, W. K.; Tung, R. T.;

    1986-01-01

    X-ray diffraction has been used to measure the intensity profile of the two-dimensional rods of scattering from a single interface buried inside a bulk material. In both Si(111)/a-Si and Si(111)/SiO2 examples there are features in the perpendicular-momentum-transfer dependence which are not expec...... are not expected from an ideal sharp interface. The diffraction profiles are explained by models with partially ordered layers extending into the amorphous region. In the Si(111)/a-Si case there is clear evidence of stacking faults which are attributed to residual 7×7 reconstruction....

  2. O conhecimento de si como possibilidade para a transformação de si e do coletivo

    Directory of Open Access Journals (Sweden)

    Rosemary Silva da Silveira

    1999-12-01

    Full Text Available Para promover a discussão e reflexão em grupo sobre o significado do trabalho da enfermagem numa unidade cirúrgica e diante da constatação da necessidade dos trabalhadores de enfermagem conhecerem-se mais a si e entre si, como participantes e construtores de um trabalho coletivo, implementou-se uma prática, entendida como uma tecnologia do eu, que favorecesse o conhecimento de si e do outro na tentativa de transformar a si e, conseqüentemente, o coletivo. A partir da exposição verbal e individual, ao grupo, da percepção de si, propôs-se o registro escrito de qualidades e conselhos que poderiam ser atribuídos a cada membro da equipe de enfermagem. Sistematizadas as contribuições, cada participante recebeu, individualmente, o conjunto de percepções do grupo sobre si. Tais estratégias constituíram-se em espaços mobilizadores para o diálogo, a reflexão crítica e uma maior aproximação entre os trabalhadores, representando uma possibilidade de cuidado de si e de aperfeiçoamento pessoal e grupal.

  3. La retractación arbitraria, entre principios y remedios

    Directory of Open Access Journals (Sweden)

    Matteo Dellacasa

    2012-06-01

    Full Text Available En la jurisprudencia italiana se ha consolidado el enfoque según la cual el juez está legitimado para controlar el ejercicio del derecho de retractación discrecional. Ante una solicitud expresa de la parte, el juez, incluso, está obligado a verificar la conformidad de la conducta de quien ejerce el derecho con el canon de la buena fe contractual. La reflexión de la doctrina italiana se concentra prevalentemente en la dialéctica entre autonomía privada y control judicial, mientras es menos frecuentado el terreno de los remedios que siguen a la retractación arbitraria. En este segundo perfil se concentra el presente escrito. En primer lugar, se afirma que el control jurisdiccional de la retractación ad nutum es oportuno en relación con todos los contratos, y no solo en aquellos caracterizados por la asimetría de poderes entre las partes. El remedio generalmente aplicable a favor de la parte que sufre la retractación arbitraria se identifica con el resarcimiento del interés negativo: el contratante desilusionado puede obtener el reembolso de los gastos asumidos y el resarcimiento de las oportunidades de ganancias perdidas como consecuencia de la confianza depositada en la realización del negocio. En segundo lugar, se delinean los criterios que permiten identificar la retractación arbitraria. En fin, se analiza si la existencia de una relación de dependencia económica entre la empresa que se retracta arbitrariamente y su contraparte contractual puede justificar la aplicación de un remedio diferente del resarcimiento del interés negativo. El autor está orientado a responder afirmativamente. Si la empresa que sufre la retractación ilegítima ha realizado inversiones específicas –centradas en las exigencias de la contraparte y, por esto, difícilmente recuperables–, el resarcimiento del interés negativo ofrece una tutela parcial e inadecuada. Los remedios aplicables, en cambio, deben salvaguardar el interés positivo de la

  4. Relaciones entre patrimonio y territorio

    Directory of Open Access Journals (Sweden)

    Horacio Torrent Schneider

    2006-01-01

    Full Text Available Las relaciones entre patrimonio arquitectónico y territorio no son frecuentes. La ampliación de la consideración patrimonial al territorio y al paisaje se ha incrementado en los últimos años. Así muchos territorios se reconocen hoy como patrimonio porque de alguna manera se configuran por la existencia en su ámbito de situaciones u objetos considerados patrimonio. La relación entre arquitectura y patrimonio se pone en evidencia en la lectura de las extensiones territoriales por la vigencia de una cierta densidad de arquitecturas patrimoniales y relaciones históricas, pero también paisajísticas. La repetición de signos patrimoniales semejantes hace que el lugar donde ello se produce pueda ser objeto de lectura patrimonial en tanto territorio. Pero también es necesario que esas arquitecturas tengan un grado de definición en relación con el lugar para ser consideradas bajo la categoría de patrimoniales. Es decir, debe ser posible leer en la propia arquitectura alguna serie de rasgos que permitan entender que las obras fueron concebidas en una relación particular con el sitio o con su emplazamiento. Ese puede ser el caso del territorio de Chiloé, donde la densidad y repetición de ejemplares de templos de la escuela chilota habilita su consideración; pero también es en las propias iglesias que se puede leer su relación con el sitio, a través de la torre, del pórtico, del emplazamiento y su relación con el borde mar. Esta condición del patrimonio también puede surgir de una intervención que pretendidamente haya asumido ambas escalas. Es decir que la acción sobre el territorio rural y urbano pueda ser entendida desde un punto de vista arquitectónico. Este ha sido el caso del Plan Serena.

  5. Interrelaciones entre caries y sobrepeso en una población infantil

    OpenAIRE

    Sanjurjo Trigueros, Silvia

    2013-01-01

    La caries y el sobrepeso son enfermedades de etiología multifactorial, con un factor común, la dieta. Nos planteamos si los escolares que padecen sobrepeso u obesidad presentan más caries que los escolares con peso adecuado, es decir, si existe una relación entre la caries dental y el sobrepeso u obesidad. Además, consideramos que los escolares con sobrepeso u obesidad pueden tener una mayor frecuencia en la ingesta y un consumo más elevado de alimentos azucarados, pudiendo tener una ma...

  6. Privacy and Yin Si

    Institute of Scientific and Technical Information of China (English)

    胡迪

    2007-01-01

    <正>“Privacy” is translated as yin si in Chinese.Traditionally,in the Chinese mind,yin si is associated with something that is closed or unfair.If someone is said to have yin si,meddlers(好事者) will be attracted to pry(打探) into his or her affairs.So people always state that they don’t have yin si.

  7. Le ballet pantomime et l'Antiquité : quelques notes de réflexion : Le recours à l'Antiquité dans le ballet d'action au XVIII siècle: Sources et modèles entre reconstruction, interprétation et création.

    OpenAIRE

    Fabbricatore, Arianna

    2014-01-01

    Dans son processus de légitimation, le nouveau genre de danse théâtrale tente de trouver ses fondements théoriques dans l'Antiquité : le retour à la tradition antique, c'est-à-dire la recherche d'un modèle à imiter, apparaît comme une stratégie de justification du nouveau genre. Cependant ce retour à la tradition n'est pas sans ambigüité. Si les maîtres de ballets nourrissent l'aspiration à un modèle qui peut fournir au ballet d'action la légitimité recherchée, ils n'ignorent pas que ce modèl...

  8. PROEJA: ENTRE DESAFIOS E POSSIBILIDADES

    Directory of Open Access Journals (Sweden)

    D. H. Moura

    2012-05-01

    Full Text Available Neste trabalho, pesquisa-se a gênese e os anos iniciais de vigência do Programa de Integração da Educação Profissional à Educação Básica na Modalidade Educação de Jovens e Adultos – PROEJA – que visa oferecer oportunidades educacionais que integrem, na modalidade educação de jovens e adultos, o ensino médio à educação profissional técnica de nível médio ou o ensino fundamental à formação inicial e continuada de trabalhadores. Por meio de revisão bibliográfica e análise de documentos, analisa-se o Programa, enfocando os equívocos em sua implantação, suas possibilidades e desafios. Vale salientar que apesar de o PROEJA abranger a integração da educação profissional à educação básica, neste trabalho, a análise está concentrada na integração entre os cursos técnicos de nível médio e o ensino médio.

  9. Resonances in 28Si+28Si. II

    CERN Document Server

    Uegaki, Eiji

    2012-01-01

    Resonances observed in the 28Si+28Si collision are studied by the molecular model. In the preceding paper, it is clarified that at high spins in 28Si+28Si (oblate-oblate system), the stable dinuclear configuration of the system is equator-equator touching one, and that the axially asymmetric shape of the stable configuration of 28Si+28Si gives rise to a wobbling motion ($K$-mixing). There, the normal modes around the equilibrium have been solved and various excited states have been obtained. Those states are expected to be the origin of a large number of resonances observed. Hence their physical quantities are analyzed theoretically. The results are compared with the recent experiment performed in Strasbourg and turn out to be in good agreement with the data. Disalignments between the orbital angular momentum and the spins of the constituent 28Si nuclei in the resonance state are clarified. Moreover the analyses of the angular correlations indicate characteristic features for each normal-mode excitation. Thus...

  10. Propuesta de comunicación entre un ambiente inmersivo y el mundo real

    OpenAIRE

    Garcia, Jose Manuel; Sutz, Guillermo; Monti, Hernan; Sattolo, Iris; Lipera, Liliana; Romero, Juan Carlos; Benito, Patricia

    2015-01-01

    En este trabajo de investigación, se planteó la utilización de los mundos virtuales inmersivos a la Educación a distancia, usando el aplicativo opensouce: OpenSim. Si bien las plataformas existentes ofrecen comunicación bidirecccional entre el alumno y el profesor, estas no son en tiempo real. Para achicar esta brecha es que se presenta esta propuesta.

  11. Relación entre la Enfermedad Periodontal y Parto Prematuro

    OpenAIRE

    Quevedo García, Rodrigo

    2013-01-01

    Entender la posible relación entre una enfermedad infecciosa local muchas veces subliminar como la enfermedad periodontal y una de las complicaciones más frecuentes del embarazo como es el parto prematuro. También se intentan describir los mecanismos de esta interacción y si el tratamiento de la EP reduce el PP. Finalmente resaltar la importancia de la salud oral y especialmente periodontal en la salud istémica del individuo.

  12. Burnout e intenciones de jubilación anticipada entre empleados mayores - Burnout and early retirement intentions among older employees

    NARCIS (Netherlands)

    Henkens, C.J.I.M.; Leenders, M.

    2009-01-01

    El tema central de este artículo es la jubilación y el burnout de los empleados mayores. Analizamos si existe una relación entre las dimensiones de agotamiento emocional y despersonalización características del burnout y las intenciones de jubilación de los empleados mayores. Asimismo, se investiga

  13. Si/SiO2和Si/SiNx/SiO2超晶格的能带结构%Band structure of Si/SiO2 and Si/SiNx/SiO2 superlattices

    Institute of Scientific and Technical Information of China (English)

    魏屹; 董成军; 徐明

    2010-01-01

    利用Kronig-Penney模型从理论上计算了Si/SiO2和Si/Si/SiNx/SiO2多层膜结构中量子阱的能带结构,进一步分析了各亚层薄膜厚度对能带结构和有效质量的影响.结果发现,适当减少亚层的厚度都能使得纳米Si薄膜的带隙发生明显宽化.在Si/SiO2超晶格中,Si量子阱层带隙能量随着Si层厚度的变化符合EPLL(eV)=1.6+0.7/d2关系,与我们的计算结果十分吻合.在Si/SiNdSiO2超晶格系统中,可以通过控制各亚层厚度,尤其是Si和SiNx层厚度,均能够有效地控制发光.

  14. Como si fuera posible recoger sentimientos

    OpenAIRE

    Vayreda Puigvert, Marian; Vallès Villanueva, Joan

    2011-01-01

    Se trata de una propuesta como resultado del trabajo conjunto entre la escuela de Arte Pigment y el ESPAI ZERO1 del Museu Comarcal de la Garrotxa, destinado exclusivamente a exposiciones temporales de creación contemporánea y como continuidad de propuestas anteriores de colaboración: REPLICA23 y SONESNAT JUNIOR. Com si fos possible recollir el sofriment es un proyecto de la artista Anna Manel.la, y se consideró una propuesta interesante y un reto para conversar, intercambiar y crear con los a...

  15. La telecol.laboració en la classe de llengua extranjera entre grups heterogenis d’estudiants

    Directory of Open Access Journals (Sweden)

    Mercedes López Santiago

    2014-06-01

    Full Text Available En l'ensenyament de llengües estrangeres, nombrosos professors treballen les competències lingüístiques i comunicatives mitjançant d'activitats que inclouen les TIC. Entre algunes, es troben els projectes de telecol·laboració per Internet, intercanvis asincrònics i sincrònics entre grups d'estudiants que pertanyen a diferents comunitats lingüístiques allunyades geogràficament. El nostre objectiu ha consistit a comprovar si un projecte de telecol·laboració sincrònic entre grups heterogenis d'estudiants, és factible i si contribueix al desenvolupament de les competències comunicatives, interculturals i tecnològiques.

  16. Diferencias entre homosexuales y heterosexuales en comportamiento y personalidad

    Directory of Open Access Journals (Sweden)

    Mirta Granero

    1984-01-01

    Full Text Available La autora informa de los resultados de 120 sujetos (30 varones heterosexuales, 30 varones homosexuales, 30 mujeres heterosexuales y 30 mujeres homosexuales, a los que se aplicaron cuestionarios y tests para averiguar comportamientos y rasgos de personalidad. Para el análisis de cada rasgo o comportamiento, los datos fueron clasificados por dos variables: Orientación sexual y Sexo. Se encontraron algunas diferencias significativas entre homosexuales y heterosexuales, como así también entre varones y mujeres, independientes de su orientación sexual. Se cuestiona si algunos tests tienen validez para algunos de estos grupos. Se piensa que puede haber respuestas determinadas por la presión social en la que vive el homosexual, en vez de por la variable que se supone que mide en él. Este primer informe, es parte de un trabajo más ambicioso, que la autora está realizando en la ciudad de Rosario (Argentina

  17. L’approche sociopsychologique de Horkheimer, entre Fromm et Adorno

    Directory of Open Access Journals (Sweden)

    Katia Genel

    2010-08-01

    Full Text Available Le cadre du programme interdisciplinaire de recherche défini par Max Horkheimer dans les années 1930 doit beaucoup à Erich Fromm, qui a introduit la psychologie sociale dans la Théorie critique de la société. Or, une décennie plus tard, Fromm est la cible privilégiée des attaques et sa théorie apparaît désormais comme incompatible avec les positions défendues par Horkheimer et Adorno. Partant de ces tensions qui ont marqué l’histoire de l’École de Francfort, le présent article vise à éclaircir le déplacement qu’elles traduisent sur le plan épistémologique. Si Horkheimer et Fromm partagent des prémisses communes, le premier, dans son travail avec Adorno, se rapproche de manière croissante de la doctrine freudienne alors que le second s’en éloigne. Nous voudrions montrer que l’accord entre Fromm et Horkheimer fut surtout négatif puisqu’il portait sur la critique de Freud : les divergences entre les deux penseurs apparaissent clairement, dès lors qu’on pose en profondeur la question de l’usage de la psychanalyse pour analyser l’un des problèmes centraux de la théorie de la société, l’antagonisme entre individu et société.

  18. Evaluation of the security of a hydrogen producing plant by means of the S I cycle coupled to a nuclear reactor of high temperature; Evaluacion de la seguridad de una planta productora de hidrogeno mediante el ciclo SI acoplada a un reactor nuclear de alta temperatura

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz S, T.; Francois, J. L.; Nelson, P. F. [UNAM, Facultad de Ingenieria, Departamento de Sistemas Energeticos, Paseo Cuauhnahuac No. 8532, Col. Progreso, 62550 Jiutepec, Morelos (Mexico); Cruz G, M. J., E-mail: truizsmx@yahoo.com.mx [UNAM, Facultad de Quimica, Ciudad Universitaria, 04510 Mexico D. F. (MX)

    2011-11-15

    At the present one of the processes that demonstrates, theoretically, to be one of the most efficient for the hydrogen production is the thermal-chemistry cycle Sulfur-Iodine. One way of obtaining the temperature ranges required by the process is through the helium coming from a very high temperature reactor. The coupling of the chemical plant with the nuclear plant presents aspects of security that should be analyzed; among them the analysis of the danger of the process materials is, with the purpose of implementing security measures to protect the facilities and equipment s, the environment and the population. These measures can be: emergency answer plans of the stations, definition of the minimum distance required among facilities, determination of the exclusion area, etc. In this study simulations were made with the computer code Phast in order to knowing the possible affectation areas due to the liberation of a great quantity of energy due to a helium leak to very high temperature, of toxic materials or by a possible hydrogen combustion. The results for the liberations of sulfuric acid, hydrogen, iodine, helium and sulfur dioxide are shown, specially. The operation conditions were taken of a combination of the preliminary design proposed by General Atomics and the optimized conditions by the Korea Advanced Institute of Science and Technology, considering a production of 1 kg-mol/s of hydrogen. The iodine was the material that presented a major affectation area. (Author)

  19. La frontière entre le bilād al-islām et le bilād al-Nūba : enjeux et ambiguïtés d’une frontière immobile (VIIe-XIIe siècle The frontier between bilād al-islām and bilād al-Nūba: issues and ambiguities of fixed boundary (seventh-twelfth century

    Directory of Open Access Journals (Sweden)

    Robin Seignobos

    2011-03-01

    Full Text Available Le bilād al-Nūba occupe dans la nomenclature juridique et idéologique arabo-musulmane une position particulière. L’échec de la conquête de la Nubie au viie siècle a débouché sur la signature d’un traité de paix unique qui a fait de cet espace un territoire à part. Ces spécificités ne resteront pas sans effet sur l’appréhension de la frontière qui sépare les pays d’Islam de la Nubie. S’efforçant de définir la limite du bilād al-islām, les géographes arabes semblent unanimes à désigner Assouan comme la dernière ville frontière de l’islam chargée de défendre l’Égypte de l’ennemi latent que demeure, malgré la paix, le pays des Nubiens. Néanmoins, en examinant plus attentivement ces témoignages, ce dispositif frontalier se révèle en réalité plus complexe. Il se structure autour d���un élément naturel, la première cataracte, qui, loin de constituer la barrière infranchissable que certains de ces auteurs souhaiteraient y voir, forme plutôt un espace de transition entre ces deux mondes. Or, c’est justement en tirant parti des porosités de cette frontière que l’islam parvient, sans que cette démarcation soit véritablement remise en question, à étendre son influence bien au-delà de celle-ci.Bilād al-Nūbaholds a special place in the Arab-Islamic juridical and ideological nomenclature. As a consequence of the failure to conquer Nubia in the 7th century, a peace treaty was signed that singled out this territory. These specificities were not devoid of consequences on the perception of the frontier between Islamic countries and Nubia. When delimiting bilād al-islām, Arabic geographers unanimously agreed in designating Aswan as the last frontier-town of Islam, in charge of defending Egyptian territory from potential Nubian enemies.A closer examination of the sources brings to light the unexpected complexity of this frontier system. It was apparently shaped around a geographical

  20. L’effet de présence : entre image fixe et image animée, les représentations de la Passion (fin XIXe-début XXe siècle In search of presence: Representations of the Passion between the fixed and moving image (late 19th, early 20th century

    Directory of Open Access Journals (Sweden)

    Isabelle Saint-Martin

    2008-06-01

    Full Text Available Les représentations de la Passion et de la Vie de Jésus ont figuré parmi les premiers titres des débuts du cinéma. A posteriori, la critique des films religieux, notamment dans les années soixante, a été sévère pour ces tentatives jugées plus commerciales que très inspirées. L’intérêt pour le cinéma des premiers temps s’est approfondi dans les dernières décennies et favorise une autre approche de ces productions des années 1895-1920. Restituer l’univers visuel dans lequel ces films ont pris naissance permet de préciser les modalités de représentation des sujets biblique, en lien avec l’historicisme et l’orientalisme. Outre les liens étroits avec la peinture et la photographie, ces premiers films retrouvent certains effets narratifs des jeux de la Passion ou des projections d’images fixes encore abondantes au tournant du XXe siècle. S’attacher à la conception de la figuration contribue à cerner le « désir de voir » et l’effet de présence christique qui se manifestent dans ces premières Passion filmées.Representations of the Passion and the Life of Jesus Christ were a popular topic in early cinema. Retrospective criticism, especially in the 1960’s, was judgmental towards the first religious films, insofar as they were regarded more as commercially driven reenactments than inspired works. Interest in early cinema deepened in recent decades, and has led to a different reading of productions from the period 1895-1920. By restoring the universe of visual references in which these films arose, we are able to relate representations of biblical subjects to movements in historicism and Orientalism. Beyond their close relationship with painting and photography, these early films also reproduced the narrative effects of Passion plays or projections of fixed images that were still widespread at the turn of the 20th century. A focus on figurative conception will help us reconnect with the "need to see" and

  1. Aplicación del bioensayo EROD-H4IIE para la determinación de dioxinas en carnes de pollos broiler: un estudio de equivalencia con la cromatografía de gases de alta resolución acoplada a espectrometría de masas de alta resolución Application of the EROD-H4IIE bioassay for the determination of dioxins in broiler chicken meat: an equivalence study with high resolution gas chromatography coupled to high resolution mass spectrometry

    Directory of Open Access Journals (Sweden)

    JT Schoffer

    2011-01-01

    Full Text Available En el presente estudio se aplicó el bioensayo EROD con línea celular H4IIE para determinar la equivalencia de resultados para carnes de pollo, entre el bioensayo EROD-H4IIE en pg TCDD-EQ/g de tejido y los resultados de la cromatografía de gases de alta resolución acoplada a espectrometría de alta resolución (HRGC/HRMS en pg WHO-TEQ/g de grasa. Para lo anterior se utilizaron 41 muestras compuestas de trutros de pollo. Éstas fueron obtenidas en la planta faenadora de 4 planteles diferentes de Chile, durante el beneficio de animales (38 y 43 días de edad entre los años 2004 y 2007. Cada muestra fue analizada mediante ambas técnicas analíticas. Con los resultados se determinó un modelo de regresión para la equivalencia de ambas técnicas. De esta forma el modelo obtenido fue: HRGC/HRMS = 0,481 + 0,051[EROD-H4IIE]², R² = 0,885, en que para un valor en EROD-H4IIE de 2,2 pg TCDD-EQ/g de tejido se estima que corresponderá a 0,73 pg WHO-TEQ/g de grasa en HRGC/HRMS. Además, para el mismo valor de EROD-H4IIE con un 95% de confianza, se obtendrá una estimación como límite superior que equivaldrá a 0,83 pg WHO-TEQ/g de grasa en HRGC/HRMS. Al tomar el mismo valor de EROD-H4IIE con un 99% de confianza, se estima un límite superior que equivaldrá a 0,88 pg WHO-TEQ/g de grasa en HRGC/HRMS. De esta manera se concluye que el bioensayo EROD-H4IIE puede ser aplicado como método de cribado en sistemas de producción animal y específicamente en producción de pollos broiler.The EROD bioassay with H4IIE cell line was applied in this study to determine the equivalence of the results for chicken meat between the EROD-H4IIE Bioassay in pg TCDD-EQ/g of tissue, and the results of the gas chromatography coupled to high resolution spectrometry (HRGC/HRMS in pg WHO-TEQ/g of fat of TEQs. 41 compound samples of chicken drumsticks were used. The samples were obtained in slaughtering plants of 4 different production facilities of Chile, during the

  2. Estudio descriptivo y comparativo entre padres y madres que participan en un programa de prevención sobre consumo de drogas y conductas de riesgo

    OpenAIRE

    Vilaregut Puigdesens, Anna; Mateu Martínez, Clara; Virgili Tejedor, Carles; Rusiñol Estragués, Jordi; Estrada Ocón, Maria; Cabra Soler, Quim

    2012-01-01

    Objetivos: describir y analizar las competencias o habilidades parentales que tienen los padres y las madres que acuden a un programa de prevención sobre el consumo de drogas y otras conductas de riesgo, comprobar si existen diferencias entre los padres y las madres en referencia al rol parental y, por último, conocer si existen diferencias entre el rol parental y el nivel de escolarización de los hijos. Método: la muestra estuvo formada de 89 participantes (22 padres y 67 madr...

  3. Determinação de esteróides androgênicos anabólicos em urina por cromatografia gasosa acoplada à espectrometria de massas Detection of androgenic anabolic steroids (AAS in urine samples by gas chromatography-mass spectrometry

    Directory of Open Access Journals (Sweden)

    Daniel Rossi de Campos

    2005-12-01

    Full Text Available Esteróides androgênicos anabólicos (EAA são substâncias naturais, sintéticas ou semi-sintéticas derivadas da testosterona, utilizadas em atividades esportivas com o objetivo de melhorar o desempenho físico pelo aumento de massa e força muscular. Apesar de causarem efeitos tóxicos graves, principalmente sobre os sistemas cardiovascular, hepático e neuro-endócrino, os EAA têm sido amplamente utilizados no âmbito esportivo. Desta forma, o presente trabalho teve como objetivo a validação de um método para a determinação de esteróides e/ou seus produtos de biotransformação em amostras de urina por cromatografia gasosa acoplada à espectrometria de massas (CG-EM. O método baseou-se na hidrólise enzimática de esteróides conjugados, no emprego da extração líquido-líquido e na derivação do extrato para posterior análise por CG-EM, no modo de monitoramento seletivo de íons (SIM. O método validado cumpriu com os princípios de confiança necessários para a determinação de EAA em amostras de urina com a finalidade de controle de dopagem no esporte. Os limites de detecção dos esteróides analizados variaram de 0,5 a 15 ng/mL. Bons valores de precisão (intra e interensaio também foram obtidos (CVAndrogenic anabolic steroids (AAS are defined as natural, synthetic or semi-synthetic drugs chemically derived from testosterone, used with the aim to improve physical performance by increasing both muscle strength and mass. Despite their reported toxicological effects on the cardiovascular, hepatic and neuro-endocrine systems, the AAS have been extensively used in sports activities. The objective of this study was to validate an analytical method for the detection of AAS and/or their metabolites in urine samples. The method was based on enzymatic hydrolysis, liquid-liquid extraction, derivatization and further analysis by gas chromatography-mass spectrometry (GC-MS operated in the selected ion monitoring mode (SIM. The

  4. Electroluminescence from Si/SiO2 films deposited on p-Si substrates

    Institute of Scientific and Technical Information of China (English)

    马书懿; 萧勇; 陈辉

    2002-01-01

    The structure of Au/Si/SiO2/p-Si has been fabricated using the magnetron sputtering technique. It has a verygood rectifying behaviour. Visible electroluminescence (EL) has been observed from the Au/Si/SiO2/p-Si structureat a forward bias of 5V or larger. A broad band with one peak around 650-660 nm appears in all the EL spectra ofthe structure. The effects of the thickness of the Si layer in the Si/SiO2 films and of the input electrical power on ELspectra are studied systematically.

  5. Influence of Si on Interfacial Combination of SiCp/Al-Mg-Si Composite

    Institute of Scientific and Technical Information of China (English)

    Han Jianmin; Li Ronghua; Li Mingwei; Cui Shihai; Li Weijing; Wang Jinhua

    2004-01-01

    The scanning electron microscopy (SEM) analysis results of Si distribution in the interface between SiC reinforcements and aluminum matrix of a stir casting SiCp/Al-Mg-Si composite were presented. Results show that there is Si precipitation deposit on the interface of the composite and Si connects with SiC reinforcements in one side and connects with aluminum matrix in the other side. Si phase plays as a connecting bridge, which contributes to the interfacial combination of SiCp/Al composite.

  6. Asociación entre hipertensión arterial y el exceso de peso en niños y adolescentes entre los 8 y 18 años de colegios de Bogotá

    OpenAIRE

    González Huérfano, María Alejandra

    2015-01-01

    La epidemia global de obesidad se ha visto relacionada con el aumento de la prevalencia de hipertensión arterial en la edad pediátrica. Objetivo: Determinar la frecuencia de hipertensión arterial y obesidad en niños y adolescentes de Bogotá y establecer si existe asociación entre hipertensión arterial y el exceso de peso. Metodología: Estudio descriptivo transversal que incluyó 270 niños y adolescentes entre 8 y 18 años de dos colegio de Bogotá. Se obtuvo información sobre edad, peso, t...

  7. "El retablo de Maese Pedro" de Manuel de Falla: un diálogo entre música, literatura y política

    OpenAIRE

    Sevilla Llisterri, Inés

    2015-01-01

    En este trabajo hemos desarrollado el análisis de la ópera "El retablo de maese Pedro" (1923) de Manuel de Falla como lectura del "Quijote" (1605 y 1615) de Cervantes, desde las relaciones que establece el compositor entre música, literatura y política. Se trata, por tanto, de un estudio comparado entre ambas obras, si bien centrado en definir el diálogo que establece el compositor con Miguel de Cervantes. El título de esta tesis doctoral habla de "diálogo" entre música, literatura y polí...

  8. Correlações entre caracteres quantitativos em milho pipoca Correlation among quantitative traits in popcorn maize

    OpenAIRE

    Valéria Carpentieri-Pípolo; Hideaki Wilson Takahashi; Romeu Munashi Endo; Marcos Rafael Petek; Adilson Luiz Seifert

    2002-01-01

    Em um programa de melhoramento, o conhecimento da grandeza das associações entre caracteres de interesse, é de fundamental importância na obtenção de populações melhoradas. O presente trabalho teve como objetivo determinar as correlações genotípicas, fenotípicas e ambientais entre caracteres quantitativos em milho pipoca. Foram avaliados nove genótipos de milho pipoca dispostos no campo em delineamento em blocos casualizados com oito repetições. Os genótipos UEL ZP, UEL SI e UEL PAP revelaram...

  9. Relaciones entre gratitud y variables de personalidad

    OpenAIRE

    Alarcón,Reynaldo; Morales de Isasi,Carmen

    2012-01-01

    Se aborda la probable relación entre la gratitud, medida por la Escala de Gratitud, desarrollada por el primer autor, y variables de personalidad, medidas con el Inventario de Personalidad NEO PI-R, de P.T. Costa & R. R. McCrae. Encontramos una alta correlación positiva entre Gratitud y el factor A. Amabilidad (r = .293; p < .01). A esta asociación contribuyen cinco de sus facetas: Confianza, Franqueza, Sensibilidad hacia los demás, Altruismo y Actitud Conciliadora, con correlaciones esta...

  10. Introduction of atomic H into Si3N4/SiO2/Si stacks

    Institute of Scientific and Technical Information of China (English)

    JIN Hao; WEBER K.J.; LI Weitang; BLAKERS A.W.

    2006-01-01

    Atomic H generated by a plasma NH3 source at 400 ℃ was demonstrated to passivate dehydrogenated Si3N4/SiO2/Si stacks effectively by bonding with defectsin the Si3N4 film and at the Si-SiO2 interface. A subsequent anneal in N2 after atomic H reintroduction was demonstrated to further improve passivation of the Si-SiO2 interface. Isothermal and isochronal anneals in N2 were carried out in order to determine the optimized annealing conditions.

  11. SiC Technology

    Science.gov (United States)

    Neudeck, Philip G.

    1998-01-01

    Silicon carbide (SiC)-based semiconductor electronic devices and circuits are presently being developed for use in high-temperature, high-power, and/or high-radiation conditions under which conventional semiconductors cannot adequately perform. Silicon carbide's ability to function under such extreme conditions is expected to enable significant improvements to a far-ranging variety of applications and systems. These range from greatly improved high-voltage switching [1- 4] for energy savings in public electric power distribution and electric motor drives to more powerful microwave electronics for radar and communications [5-7] to sensors and controls for cleaner-burning more fuel-efficient jet aircraft and automobile engines. In the particular area of power devices, theoretical appraisals have indicated that SiC power MOSFET's and diode rectifiers would operate over higher voltage and temperature ranges, have superior switching characteristics, and yet have die sizes nearly 20 times smaller than correspondingly rated silicon-based devices [8]. However, these tremendous theoretical advantages have yet to be realized in experimental SiC devices, primarily due to the fact that SiC's relatively immature crystal growth and device fabrication technologies are not yet sufficiently developed to the degree required for reliable incorporation into most electronic systems [9]. This chapter briefly surveys the SiC semiconductor electronics technology. In particular, the differences (both good and bad) between SiC electronics technology and well-known silicon VLSI technology are highlighted. Projected performance benefits of SiC electronics are highlighted for several large-scale applications. Key crystal growth and device-fabrication issues that presently limit the performance and capability of high temperature and/or high power SiC electronics are identified.

  12. Mechanical instabilities and piezoresistivity of SiGe/Si microtubes

    Science.gov (United States)

    Zhang, Li; Dong, Lixin; Nelson, Bradley J.

    2007-10-01

    Mechanical instabilities and piezoresistivity of individual rolled-up SiGe/Si microtubes are investigated using nanorobotic manipulation. By applying this technique, as-fabricated one-end-fixed SiGe/Si microtubes can be cut and picked up from the substrate to examine their mechanical and electromechanical properties in a free space. Individual SiGe/Si microtubes show typical Euler buckling when the uniaxial compressive load is larger than a critical value. Moreover, experiments show that 1.6-turn rolled-up SiGe/Si microtubes have similar mechanical stability to ideal seamless tubes though the former ones have a spiral-like cross sectional area instead of an ideal ring. According to the measured I-V properties, SiGe/Si microtubes show positive piezoresistivity under compressive loads.

  13. Relación entre los movimientos oculares, la comprensión lectora y el rendimiento escolar

    OpenAIRE

    Montero-Rodríguez, Carmen María

    2013-01-01

    Las dificultades de lectura que manifiestan algunos alumnos es una cuestión preocupante para docentes y profesionales de la enseñanza. Si bien, es habitual que, de manera preventiva no se evalúen las dificultades neurológicas relacionadas con la funcionalidad visual. En este trabajo se pretende comprobar si existe algún tipo de relación entre el rendimiento escolar que obtienen alumnos de educación primaria, la comprensión lectora y la motilidad ocular. La investigación que se lleva a cabo...

  14. Electronic Structure of Si1-xIVx/Si Superlattices on Si(001)

    Institute of Scientific and Technical Information of China (English)

    CHEN Jie; L(U) Tie-Yu; HUANG Mei-Chun

    2007-01-01

    We have preformed systematical ab initio studies of the structural and electronic properties of short-period Si1-xIVx/Si (x = 0.125, 0.25, 0.5,IV=Ge, Sn) superlattices (SLs) grown along the [001] direction on bulk Si. The present calculations reveal that the Si0.875 Ge0.125/Si, Si0.75 Ge0.25/Si and Si0.875Sn0.125/Si axe the Γ-point direct bandgap semiconductors. The technological importance lies in the expectation that the direct gap Si1-xIVx/Si SLs may be used as components in integrated optoelectronic devices, in conjunction with the already well-established and highly advanced silicon technology.

  15. Photoelectric properties of n-SiC/n-Si heterojunctions

    Directory of Open Access Journals (Sweden)

    Semenov A. V.

    2012-10-01

    Full Text Available Photovoltaic effect in isotype heterotructure formed by nanocrystalline silicon carbide films on single crystal n-Si substrates (n-SiC/n-Si heterojunction was studied. The films were produced by direct ionic deposition method. The model that takes into account the quantum wells and potential barriers caused by band offsets was proposed to explain the current-voltage characteristics and photovoltaic properties of the heterostructure n-SiC/n-Si.

  16. RELACIÓN ENTRE LOS NIVELES DE AUTOESTIMA Y ESTRÉS EN ESTUDIANTES UNIVERSITARIOS

    Directory of Open Access Journals (Sweden)

    Leticia Ancer Elizondo

    2011-01-01

    Full Text Available El presente estudio exploró la relación entre el estrés y la autoestima en 219 jóvenes de una universidad privada del área metropolitana de Monterrey (México, además de determinar si hay diferencias por género y por estatus laboral. Se utilizó la Escala de Estrés Percibido de Cohen y la Escala de Autoestima de Rosenberg, ambas en formato electrónico. Los resultados obtenidos indican la presencia de una correlación negativa entre estrés y autoestima, incrementándose en los jóvenes que solamente estudian. Asimismo, se encontraron diferencias significativas en estrés y autoestima en la muestra en función del estatus laboral.

  17. RELACIÓN ENTRE LOS NIVELES DE AUTOESTIMA Y ESTRÉS EN ESTUDIANTES UNIVERSITARIOS

    OpenAIRE

    Leticia Ancer Elizondo; Cecilia Meza Peña; Edith G. Pompa Guajardo; Francisco Torres Guerrero; René Landero Hernández

    2011-01-01

    El presente estudio exploró la relación entre el estrés y la autoestima en 219 jóvenes de una universidad privada del área metropolitana de Monterrey (México), además de determinar si hay diferencias por género y por estatus laboral. Se utilizó la Escala de Estrés Percibido de Cohen y la Escala de Autoestima de Rosenberg, ambas en formato electrónico. Los resultados obtenidos indican la presencia de una correlación negativa entre estrés y autoestima, incrementándose en los jóvenes que solamen...

  18. Correlation between Light Emissions from Amorphous-Si:H/SiO2 and nc-Si/SiO2 Multilayers

    Institute of Scientific and Technical Information of China (English)

    MA Zhong-Yuan; HUANG Xin-Fan; CHEN Kun-Ji; FENG Duan; HAN Pei-Gao; LI Wei; CHEN De-Yuan; WEI De-Yuan; QIAN Bo; LI Wei; XU Jun; XU Ling

    2007-01-01

    We investigate the properties of light emission from amorphous-Si:H/SiO2 and nc-Si/SiO2 multilayers (MLs). The size dependence of light emission is well exhibited when the a-Si:H sublayer thickness is thinner than 4nm and the interface states are well passivated by hydrogen. For the nc-Si/SiO2 MLs, the oxygen modified interface states and nanocrystalline silicon play a predominant role in the properties of light emission. It is found that the light emission from nc-Si/SiO2 is in agreement with the model of interface state combining with quantum confinement when the size of nc-Si is smaller than 4 nm. The role of hydrogen and oxygen is discussed in detail.

  19. A comparative study of electroluminescence from Ge/SiO2 and Si/SiO2 films

    Institute of Scientific and Technical Information of China (English)

    Ma Shu-Yi; Chen Hui; Xiao Yong; Ma Zi-Jun; Sun Ai-Min

    2004-01-01

    Ge/SiO2 and Si/SiO2 films were deposited using the two-target alternation magnetron sputtering technique. The Au/Ge/SiO2/p-Si and Au/Si/SiO2/p-Si structures were fabricated and their electroluminescence (EL) characteristics were comparatively studied. Both Au/Ge/SiO2/p-Si and Au/Si/SiO2/p-Si structures have rectifying property. All the EL spectra from the two types of the structure have peak positions around 650-660 nm. The EL mechanisms of the structures are discussed.

  20. Incrementando las relaciones comerciales entre Colombia y China

    Directory of Open Access Journals (Sweden)

    JAIME RAFAEL AHCAR OLMOS

    2008-01-01

    Full Text Available Después de las reformas de fi nales de los años setenta, China consiguió su despegue económico a tal punto que, en la actualidad, se consolida como uno de los mercados más importantes del mundo, recibiendo la atención de investigadores y hombres de negocios a lo largo del planeta. En Colombia existen pocos estudios que hayan explorado las relaciones comerciales con China; en tal sentido, el presente artículo ofrece una amplia revisión de fuentes estadísticas y referencias bibliográfi cas, dando luces sobre las características y los factores que afectan las relaciones comerciales bilaterales. Los resultados muestran que, si bien China es un valioso proveedor de mercancías para Colombia, las exportaciones hacia ese país aún se encuentran por debajo de su potencial, y se genera un défi cit comercial enorme. También muestra que las exportaciones colombianas hacia China se hallan concentradas en unos pocos productos y que dado el tamaño y potencialidad de esta economía, se deberían comenzar negociaciones comerciales que busquen la fi rma de un acuerdo de libre comercio que permita incrementar el comercio entre ambos países.

  1. Integração entre epidemiologia e internet

    Directory of Open Access Journals (Sweden)

    Sérgio Ribeiro dos Santos

    2000-12-01

    Full Text Available O presente estudo tem como objetivo apresentar algumas reflexões teóricas sobre a Internet como uma ferramenta de integração no serviço de epidemiologia. Nessa perspectiva, focaliza a epidemiologia e a Internet, a Internet e a pesquisa cooperativa, e, por fim, a importância da Internet no processo de comunicação epidemiológica. A integração entre o saber epidemiológico e o uso da Internet para divulgação do conhecimento é enfatizada como um dos maiores beneficios dessa tecnologia que globaliza a informação e transcende as formas tradicionais de comunicação. Todavia, ressalta-se que essa tecnologia, por si só, não é a solução para resolver os problemas funcionais dos sistemas de informação em saúde.

  2. Relación entre movimientos sacádicos, lectura y rendimiento escolar

    OpenAIRE

    Alonso-Gutiérrez, Miriam

    2013-01-01

    La lectura es un elemento fundamental para el aprendizaje escolar. Para poseer una lectura eficaz es necesario combinar alta velocidad con alta comprensión y, si no se lleva a cabo como se debe, es necesario mejorarla conociendo todos los procesos que intervienen. Den tro de los procesos de percepción de la lectura se encuentra la visión, de la que el siguiente estudio destaca la importancia de los movimientos sacádicos. En este trabajo se analiza la relación existente entre los movi...

  3. Xopan y Tonalco, los colores de las estaciones entre los antiguos nahuas

    OpenAIRE

    Dupey García, Elodie

    2013-01-01

    Note portant sur l’auteur COLORES, LUCES Y ESTACIONES EN LA COSMOVISIÓN NAHUA En las culturas indígenas de México, como en muchas sociedades antiguas y tradicionales, los colores mantienen relaciones esenciales con los elementos del medio ambiente y entre ellos los fenómenos meteorológicos y astronómicos. Esto parece lógico si recordamos que el primer contacto del ser humano con el cromatismo se da en la naturaleza donde se producen deslumbrantes manifestaciones celestes y coloreadas como el ...

  4. Features of Mg2Si Layer Growth in Si/Mg2Si Multilayers

    Directory of Open Access Journals (Sweden)

    L.E. Konotopskyi

    2016-06-01

    Full Text Available Features of magnesium siliced layer growth in Si/Mg2Si multilayers in initial state and after thermal annealing were studied by methods of transmission electron microscopy and X-Ray scattering. As-deposited magnesium silicide layers are amorphous with nanocrystal inclusions of metastable h-Mg2Si. Formation of Mg2Si in hexagonal modification occurs under the influence of stress produced by silicon layers. At T = 723 К Mg2Si layers finished crystallizes in hexagonal modification, with some coarsening of grains. That is accompanied with 7.3 % reduction in period of the Si/Mg2Si multilayer.

  5. Photoreflectance Spectroscopy for Study of Si/SiGe/Si Heterostructure

    Institute of Scientific and Technical Information of China (English)

    Liu Zhihong; Chen Changchun; Lin Huiwang; Xiong Xiaoyi; Dou Weizhi; Tsien Pei-Hsin

    2004-01-01

    UHVCVD-grown Si/Si1- xGex/Si heterostructure was investigated by Photoreflectance spectroscopy (PR). The principle of PR used in semiconductor film was thoroughly described. According to the E1 transition energy in the Si1- xGex alloy, the Ge content in SiGe film with constant composition can be accurately characterized. In this study, determine the composition uniformity of larger diameter SiGe epiwafer by PR mapping technique was determined. These results show PR is very promising for Si1- xGex epilayer characterization with constant Ge content and can provide film measurements for production-worthy line monitor.

  6. a-Si/c-Si heterojunction solar cells on SiSiC ceramic substrates

    Institute of Scientific and Technical Information of China (English)

    LI Xudong; XU Ying; CHE Xiaoqi

    2006-01-01

    Silicon thin-film solar cells are considered to be one of the most promising cells in the future for their potential advantages, such as low cost, high efficiency, great stability, simple processing, and none-pollution. In this paper, latest progress on poly-crystalline silicon solar cells on ceramic substrates achieved by our group was reported. Rapid thermal chemical vapor deposition (RTCVD) was used to deposited poly-crystalline silicon thin films, and the grains of as-grown film were enlarged by Zone-melting Recrystallization (ZMR). As a great changein cell's structure, traditional diffused pn homojunction was replaced by a-Si/c-Si heterojunction, which lead is to distinct improvement in cell's efficiency.A conversion efficiency of 3.42% has been achieved on 1cm2 a-Si/c-Si heterojunction solar cell ( Isc =16.93 mA, Voc =310.9 mV, FF =06493, AM =1.5 G,24 ℃), while the cell with diffused homojunction only gotan efficiency of 0.6%. It indicates that a-Si emitter formed at low temperature might be more suitable for thin film cell on ceramics.

  7. The property of Si/SiGe/Si heterostructure during thermal budget characterized by HRXRD

    Institute of Scientific and Technical Information of China (English)

    CHEN Chang-Chun; LIU Zhi-Hong; HUANG Wen-Tao; DOU Wei-Zhi; ZHANG Wei; TSIEN Pei-Hsin; ZHU De-Zhang

    2003-01-01

    Si/SiGe/Si heterostructures grown by ultra-high-vacuum chemical vapor deposition (UHVCVD) werecharacterized by Rutherford backscattering/Channeling (RBS/C) together with high resolution X ray diffraction(HRXRD). High quality SiGe base layer was obtained. The Si/SiGe/Si heterostructures were subject to conventionalfurnace annealing and rapid thermal annealing with temperature between 750 ℃ and 910 ℃. Both strain and its re-laxation degree in SiGe layer are calculated by HRXRD combined with elastic theory, which are never reported inother literatures. The rapid thermal annealing at elevated temperature between 880 ℃ and 910 ℃ for very short timehad almost no influence on the strain in Si0.84Ge0. 16 epilayer. However, high temperature (900℃) furnace annealingfor 1h prompted the strain in Si0.84Ge0.16 layer to relax.

  8. Si/SiGe/Si HBT的直流特性和低频噪声%Si/SiGe/Si HBT's DC Characterization and Its Low-frequency Noise

    Institute of Scientific and Technical Information of China (English)

    廖小平; 张中平

    2003-01-01

    在对Si/SiGe/Si HBT及其Si兼容工艺的研究基础上,研制成功低噪声Si/SiGe/Si HBT,测试和分析了它的直流特性和低频噪声特性,为具有更好的低噪声性能的Si/SiGe/Si HBT的研究建立了基础.

  9. La violence verbale entre catholiques et protestants au XVIe siècle

    Directory of Open Access Journals (Sweden)

    Georges Farid

    2006-09-01

    Il ne s’agit point d’identifier qui est le champion de l’expression injurieuse mais bien de décrire simplement les termes en question et d’interpréter ce que traduisent ces paroles véhémentes : incompréhension de l’autre, rejet, haine. Y aurait-il une leçon à tirer dans l’utilisation d’un tel langage qui nous offre toute la latitude d’humilier les autres par l’expression la plus vulgaire (mots grossiers ou l’expression la plus subtile (ironie, sarcasme.

  10. Commentaire du Concordat de 1801 entre la France et le Saint-Siège

    OpenAIRE

    Jeangène Vilmer, Jean-Baptiste

    2007-01-01

    International audience; We offer here a commentary on the text of the 1801 Concordate between Bonaparte and Pius VII, a classical and oft discussed subject. We seek a clear and synthetic presentation of the 17 articles that brought religious peace to France in a troubled time. In two parts, we will show why the Concordate is a dexterous compromise that, on the one hand, satisfied religion and the Republic by recognizing that the religion of « the vast majority of the French » has the right to...

  11. El rostro bifronte de la ciencia: notas sobre la relación entre ciencia e ideología en Habermas y Althusser

    OpenAIRE

    Martínez, Lisandro Alejo

    2015-01-01

    El presente trabajo aborda la relación entre ciencia e ideología a través de la revisión crítica de las perspectivas de Jürgen Habermas y Louis Althusser. Nos interesa indagar sobre el carácter difuso de los límites entre ambos conceptos en el contexto del capitalismo tardío, de donde surge la pregunta acerca de si es posible pensar la ciencia como ideología. Si fuera así, ¿cuáles son los rasgos de la ideología y de la ciencia orientados a trascender la oposición entre verdad y falsedad? Para...

  12. Flexible micromorph tandem a-Si/µc-Si solar cells

    OpenAIRE

    Söderström, Thomas; Haug, Franz-Joseph; Terrazzoni-Daudrix, Vanessa; Ballif, Christophe

    2010-01-01

    The deposition of a stack of amorphous (a-Si:H) and microcrystalline (µc- Si:H) tandem thin film silicon solar cells (micromorph) requires at least twice the time used for a single junction a-Si:H cell. However, micromorph devices have a higher potential efficiency, thanks to the broader absorption spectrum of µc-Si:H material. High efficiencies can only be achieved by mitigating the nanocracks in the µc-Si:H cell and the light-induced degradation of the a- Si:H cell. As a result,...

  13. Effect of Si/Si1-yCy/Si Barriers on the Characteristics of Si1-xGex/Si Resonant Tunneling Structures

    Institute of Scientific and Technical Information of China (English)

    HAN Ping; CHENG Xue-Mei; Masao Sakuraba; YoungCheon Jeong; Takashi Matsuura; Junichi Murota

    2000-01-01

    P-type double barrier resonant tunneling diodes (RTD) with the single Si0.6Ge0.4 quantum well and double Si0.6 Ge0.4 spacer have been realized by using an ultra clean low-pressure chemical vapor deposition system. The effect of Si1-yCy layer on the characteristics of the devices was shown by comparing the current-voltage (Ⅰ-Ⅴ) characteristics of RTD's of the barriers of Si layers with that of Si/Si1-yCy/Si structures. The peak voltage was gradually increased and the resonant current decreased obviously with increasing C content in the Si/Si1-yCy/Si barriers. The origin of the phenomena above can be attributed to the C related deep acceptor levels in the Si/Si1-yCy/Si barriers. The possible mechanism for the observed Ⅰ-Ⅴcharacteristics was shown more clearly by increasing C content to 3% and changing the thicknesses of Si and Si1-yCy layers in the Si/Si1-yCy/Si barriers.

  14. EntreComp: The Entrepreneurship Competence Framework.

    OpenAIRE

    BACIGALUPO MARGHERITA; KAMPYLIS PANAGIOTIS; Punie, Yves; VAN DEN BRANDE Lieve

    2016-01-01

    The development of the entrepreneurial capacity of European citizens and organisations is one of the key policy objectives for the EU and Member States. Ten years ago, the European Commission identified sense of initiative and entrepreneurship as one of the 8 key competences necessary for a knowledge-based society. The EntreComp framework presented in this report proposes a shared definition of entrepreneurship as a competence, with the aim to raise consensus among all stakeholders and to est...

  15. A desnecessidade do trabalho entre pescadores artesanais

    Directory of Open Access Journals (Sweden)

    Cristiano Wellington Norberto Ramalho

    2015-04-01

    Full Text Available As relações socioculturais e econômicas, entre alguns grupos de pescadores artesanais, não colocam como entes antagônicos trabalho e tempo livre. Do contrário, tais relações celebram aproximações entre saber-fazer pesqueiro, lazer e vida, formando e conformando um todo societário. Inseridos nesse quadro, estão os pescadores artesanais do mar-de-fora da praia de Suape, no município do Cabo de Santo Agostinho, litoral sul de Pernambuco, distante 50 km de Recife. Este artigo busca desvelar a mencionada moral do trabalho e do tempo livre no fazer cotidiano de pescadores dessa Praia, com base na pesquisa etnográfica e na história de vida de 13 pescadores. No geral, identificou-se que há uma moral do trabalho que se confunde à moral do tempo livre, pois o cerceamento de uma delas representa limites à outra. Assim, para esses homens, definir o que é um ser liberto ou cativo liga-se ao encontro indissociável, em termos práticos e simbólicos, entre as referidas morais, o que é essencial para classificar o fazer-se pescador artesanal em seu sentido pleno fundamentado na desnecessidade do trabalho.

  16. Si-to-Si wafer bonding using evaporated glass

    DEFF Research Database (Denmark)

    Reus, Roger De; Lindahl, M.

    1997-01-01

    Anodic bonding of Si to Si four inch wafers using evaporated glass was performed in air at temperatures ranging from 300°C to 450°C. Although annealing of Si/glass structures around 340°C for 15 minutes eliminates stress, the bonded wafer pairs exhibit compressive stress. Pull testing revealed...

  17. Si nanoparticle interfaces in Si/SiO solar cell materials

    DEFF Research Database (Denmark)

    Kilpeläinen, S.; Kujala, J.; Tuomisto, F.;

    2013-01-01

    Novel solar cell materials consisting of Si nanoparticles embedded in SiO2 layers have been studied using positron annihilation spectroscopy in Doppler broadening mode and photoluminescence. Two positron-trapping interface states are observed after high temperature annealing at 1100 °C. One...... of the states is attributed to the (SiO2/Si bulk) interface and the other to the interface between the Si nanoparticles and SiO2. A small reduction in positron trapping into these states is observed after annealing the samples in N2 atmosphere with 5% H2. Enhanced photoluminescence is also observed from...

  18. Aplicación de extracción en fase sólida magnética acoplada a sistemas de separación instrumentales para el análisis de residuos de antibióticos en leche

    OpenAIRE

    Ibarra Ortega, Israel Samuel

    2013-01-01

    El uso de antibióticos como promotores del crecimiento en animales destinados al consumo humano representa una práctica frecuente, dentro de los antibioticos más usados con esta finalidad se encuentran las sulfamidas, quinolonas y tetraciclinas. Su aplicación indiscriminada puede ocacionar que residuos de estos persistan y puedan ocasionar problemas al consumidor (alergias, problemas gastrointestinales, desarrollo de resistencias, entre otros), a causa de esta problemática se han desarrollado...

  19. Electronic states at Si-SiO2 interface introduced by implantation of Si in thermal SiO2

    International Nuclear Information System (INIS)

    Interface traps due to excess Si introduced into the Si-SiO2 system by ion implantation are investigated. Implanted oxides are shown to have interface traps at or slightly above the Si conduction band edge with densities proportional to the density of off-stoichiometric Si at the Si-SiO2 interface. Diluted oxygen annealing is shown to result in physical separation of interface traps and equilibrium substrate electrons, demonstrating that ''interface'' states are located within a 0.5 nm thick layer of SiO2. Possible charge trapping mechanisms are discussed and the effect of these traps on MOS transistor characteristics is described using a sheet charge model. (author)

  20. Resonant Tunnelling and Storage of Electrons in Si Nanocrystals within a-SiNx/nc-Si/a-SiNx Structures

    Institute of Scientific and Technical Information of China (English)

    WANG Xiang; HUANG Jian; ZHANG Xian-Gao; DING Hong-Lin; YU Lin-Wei; HUANG Xin-Fan; LI Wei; XU Jun; CHEN Kun-Ji

    2008-01-01

    @@ The a-SiNx/nanocrystalline silicon (nc-Si)/a-SiNx sandwiched structures with asymmetric double-barrier are fabricated in a plasma enhanced chemical vapour deposition (PECVD) system on p-type Si substrates. The nc-Si layer in thickness 5nm is fabricated from a hydrogen-diluted silane gas by the layer-by-layer deposition technique. The thicknesses of tunnel and control SiNx layers are 3nm and 20nm,respectively. Frequency-dependent capacitance spectroscopy is used to study the electron tunnelling and the storage in the sandwiched structures.Distinct frequency-dependent capacitance peaks due to electrons tunnelling into the nc-Si dots and capacitance-voltage (C- V) hysteresis characteristic due to electrons storage in the nc-Si dots are observed with the same sample.

  1. GUVERNAREA DIGITALA SI MODELELE SALE

    OpenAIRE

    Mihaela SAVA; Sofia Elena COLESCA

    2007-01-01

    Aceasta lucrare descrie modele alternative de guvernare electronica, in concordanta cu abordarile diferite ale guvernului In legatura cu posibilitatile oferite de ICT (suport pentru informatii, comunicare si interactiune, managementul cunostintelor). Mai precis, este vorba de o trecere in revista si o analiza a modelelor de guvernare dezvoltate de o initiativa internationala orientata spre cresterea si sustinerea utilizarii ICT (tehnologiile informatiei si comunicatiilor) in contextul guverna...

  2. Photoluminescence from SiO sub 2 /Si/SiO sub 2 structures

    CERN Document Server

    Photopoulos, P

    2003-01-01

    Si layers were developed on pre-oxidized Si wafers by decomposition of silane in a low pressure chemical vapour deposition reactor. By keeping the deposition time constant (2 min) three sets of samples were fabricated at deposition temperatures equal to 580, 610 and 625 deg C. The deposited Si layers were thinned by high temperature dry oxidation thus forming SiO sub 2 /Si/SiO sub 2 structures. Room temperature photoluminescence (PL) measurements showed that for those samples in which the thickness of the remaining Si layer was greater than approx 6 nm, the spectra exhibited a peak at approx 650 nm. Prolonged oxidations led to the formation of SiO sub 2 /nanocrystalline-Si/SiO sub 2 structures in which the thickness of the remaining nanocrystalline Si (nc-Si) layer was smaller than 3 nm. The PL spectra obtained from these structures were at least ten times stronger compared to the previous ones. The PL peak wavelength exhibited a weak dependence on the nc-Si layer thickness shifting from 800 to 720 nm for nc-...

  3. Peces de Entre Ríos

    OpenAIRE

    Miquelarena, Amalia M.

    2013-01-01

    Esta contribución forma parte de los resultados del PICT 153 de la Agencia Nacional de Promoción Científica y Técnica, dirigido por la autora, entre cuyos objetivos se encuentra la transferencia del conocimiento. Es así, que la presente iconografía, tiene como propósito difundir a diferentes niveles de la sociedad la ictiofauna de una de nuestras provincias mesopotámicas contribuyendo de esta manera a la educación ambiental y al manejo y conservación de los recursos naturales.

  4. Relación entre variables neurocognitivas y personalidad en delincuentes

    Directory of Open Access Journals (Sweden)

    Juan Antonio Becerra García

    2014-12-01

    Full Text Available Recientes estudios muestran que rasgos de personalidad del Modelo de los Cinco Factores y funciones neurocognitivas frontales comparten una misma base neurobiológica. En población penitenciaria las relaciones entre estas funciones y rasgos ha sido poco explorada. Este estudio pretende examinar la relación entre personalidad y funciones neurocognitivas en delincuentes y determinar si las medidas de funcionamiento neurocognitivo frontal contribuyen a predecir algún porcentaje de varianza en rasgos de personalidad de muestras penitenciarias. Noventa y nueve hombres (distribuidos en grupos: agresores sexuales de adultos, delincuentes no sexuales y grupo control realizaron el Inventario de Personalidad NEO de Cinco Factores (NEO-FFI y el Trail Making Test (TMT, partes A y B. La ejecución en la parte A del TMT se relaciono con el nivel de Extraversión de los delincuentes sexuales y con el nivel de Neuroticismo de delincuentes no sexuales y explica un porcentaje significativo de la varianza de estos dominios de personalidad en ambos grupos. En conclusión, la relación entre el funcionamiento neurocognitivo y la personalidad parece ser diferente en función del tipo de delito cometido, aunque los resultados deben ser interpretados de forma preliminar.

  5. RITUAL E XAMANISMO ENTRE OS KAINGANG: O TEMPO E A SOCIOCOSMOLOGIA DOS ESPAÇOS RITUAIS

    Directory of Open Access Journals (Sweden)

    Alexandre Magno Aquino

    2014-06-01

    Full Text Available A conexão espaço-tempo é interpretada a partir de dados etnográficos e de análise de (espaços rituais que indicam formas de relação social entre os Kaingang fundadas na reciprocidade de kamë e kanhru krë, as metades patrilineares e exogâmicas. Essa reciprocidade é constantemente afirmada no contexto intra e interaldeão por meio de regras de etiqueta e arranjos institucionais que envolvem, principalmente, o parentesco, o xamanismo e a liderança. De fato, os Kaingang relacionam-se entre si e com os Outros, que compõem seu cosmos, a partir da interação entre os que pertencem a uma ou outra metade, dos kujá (xamã e dos pa i (cacique, que se articulam, nesse caso, para fundar aldeias na região litorânea.

  6. XI. Si Heidegger…

    OpenAIRE

    2012-01-01

    C’est avec raison que Lyotard a refusé l’alternative : « si grand penseur, alors pas nazi ; si nazi, pas grand penseur. » Schirmacher, un apologète de Heidegger qui a la malchance de ne pas être pris en compte par l’apologie officielle de Heidegger, répète l’alternative avec sa question : « Est-ce qu’un salaud [Charakterschwein] peut être un grand philosophe ? » Il trouve certes « consternant que Heidegger ait été nazi », mais demande à la fin : « Heidegger était-il nazi ? » Pourtant, ce n’es...

  7. Entre foi et compromis tribal : 

    Directory of Open Access Journals (Sweden)

    Dridi Moez

    2007-03-01

    Full Text Available On comprend mieux l’adhésion d’Oman à l’islam, entre 628 et 633 si on l’étudie dans son contexte historique et  en relation avec les enjeux politiques et économiques de l’époque. Depuis le ive siècle de l’ère chrétienne, la côte orientale de la péninsule arabique se trouvait dans l’aire d’influence de l’empire sassanide, et la région d’Oman, Mâzun, était administrée par un gouverneur perse, marzubân, contrôlant un « roi » arabe local. Centré sur les ports de Dabâ et Suhar (Suhâr, cette entité politique bénéficiait des revenus du commerce international avec l’Asie occidentale. Les premiers contacts épistolaires du Prophète Muhammad avec les chefs de tribus et rois locaux furent suivis par une série d’accords de reconnaissance de sa tutelle spirituelle nominale, sans que l’on puisse encore parler d’ « islamisation ». C’est seulement à la mort du Prophète, que la révolte de la ridda (« apostasie » provoqua, avec une intervention militaire directe de l’État mecquois, le départ des Perses et l’entrée véritable d’Oman dans l’islam.Between Faith and Tribal Compromise: How the Region of Oman entered IslamThe adhesion of Oman to Islam between 628 and 633 is better understood when it is studied in its historical context along with its relation to the major political and economic events of the period. Starting from the 4th c. of the Christian era, the Eastern coast of the Arabic peninsula was under the influence of the Sassanid Empire, the region of Oman, Mâzun, being administrated by the Persian government, marzubân, which controlled a local Arab « king ». This political entity, centered on the ports of Dabâ and Suhar, was deriving benefit from the revenue from international trade with West Asia. The first epistolary contacts of the prophet Muhammad with the local tribal leaders and kings were followed by a series of agreements recognizing his nominal spiritual

  8. Entre la Venadita y la Medusa

    Directory of Open Access Journals (Sweden)

    Valcárcel, Amelia

    2008-06-01

    Full Text Available Feminism has made in the last decades relevant advances towards equity between men and women in western societies. However, both mysogyny and gynophobia are still at work, giving as a result a «deflation of expectations» among women who enter the worlds of politics, information, corporations, economic power, knowledge, religion or art, and find a glass ceiling in full operation. The paper focuses on women artists, examines the anger expressed in feminist art as an answer to exclusion, and argues for feminist strategies of analysis and correction of inequalities.

    El feminismo ha conseguido en los últimos años importantes avances hacia la igualdad entre hombres y mujeres en las sociedades occidentales. Y, sin embargo, tanto la misoginia como la ginofobia siguen vigentes, provocando una «deflación de expectativas » entre las mujeres que se incorporan a los mundos de la política, la información, las organizaciones empresariales, el poder económico, el saber, la religión o la creatividad, y se topan con el techo de cristal a pleno funcionamiento. El artículo se centra en las mujeres creadoras para examinar la cólera expresada en el arte feminista como respuesta a la exclusión y defender estrategias feministas de análisis y corrección de desigualdades.

  9. Funciones: traducción entre representaciones

    Directory of Open Access Journals (Sweden)

    Modesto SIERRA VÁZQUEZ

    2009-11-01

    Full Text Available RESUMEN: La traducción entre diferentes formas de representación es un aspecto esencial en la enseñanza y en el aprendizaje de las funciones, ya que permite que el alumno capture el comportamiento de una función desde diversos ángulos enriqueciendo su comprensión. En este trabajo se expone el concepto de representación en matemáticas, su evolución histórica referida al concepto de función, la traducción entre diferentes representaciones y se proponen actividades didácticas para el trabajo en el aula.ABSTRACT: The translation between differents systems of representation is an important aspect in the teaching and learning of functions, because it allows the student to acquire the behaviour of functions from differents points of view, enriching its understanding. In this paper, we expose the concept of representation in Mathematic Education, its historie evolution in relation with the concept of function, the translation between different forms of representation and we propose didactical activities for the work in the classroom.

  10. ARTICULAÇÕES ENTRE VERDADE E SUBJETIVIDADE NOS ÚLTIMOS ESTUDOS DE MICHEL FOUCAULT: SOBRE A SEPARAÇÃO ENTRE VERDADE E ESPIRITUALIDADE

    Directory of Open Access Journals (Sweden)

    Daniel Verginelli Galantin

    2012-07-01

    Full Text Available Resumo: Neste artigo apresentamos algumas características concernentes à vinculação entre verdade e subjetividade nos estudos de Michel Foucault realizados durante a década de 1980. Para isso, iniciamos com uma breve introdução onde apresentamos o novo eixo das pesquisas de nosso autor, as técnicas de si. Em seguida nos concentramos em algumas aulas do curso Hermenêutica do Sujeito, onde Foucault aponta para uma separação entre filosofia e espiritualidade no decorrer da história da filosofia, separação que tem como marco a emergência da teologia. Após fazermos uma breve contraposição entre o modo como se articulam verdade e sujeito nos estudos de Foucault (realizados na década de 1970 sobre a época moderna, em comparação com as filosofias clássicas e helênicas, defendemos que tal separação entre filosofia e espiritualidade pode ser tomada como um dos pontos significativos a partir dos quais podemos entender a articulação entre verdade e subjetividade nos últimos estudos de Foucault, assim como suas implicações políticas.Abstract: In this article our goal is to present some of the characteristics which concern the vinculation between truth and subjectivity on Michel Foucault’s 1980 research. So we begin by a short introduction where it’s presented the new axis of our author’s work, the technics of the self. After that we focus in some of the classes from Hermeneutics of the Subject on which Foucault points out a separation between philosophy and spirituality in the middle of the history of philosophy; that separation is due to the emergence of theology. After a quick contraposition between the way which truth and subject are articulated on Foucault’s studies on modernity (made on the 1970’s, and the way they are articulated on classic and hellenic philosophies, we defend that such separation between truth and spirituality may be taken as a significant point by which we can understand the articulation

  11. Radiation-induced plasmons in Si-SiO2

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The first level plasmons of Si in the pure Si state (corresponding to bonding energy (BE) of 116.95 eV) and in the SiO2 state (corresponding to BE of 122.0 eV) of Si-SiO2 prepared by irradiation hard and soft processing were studied with XPS before and after 60Co radiation.The experimental results indicate thatthere was an interface consisting of the two plasmons,this interface was extended by 60Co radiation, the fractions of the plasmon for Si in the Si-SiO2 werechanged with the variation of radiation dosage,the difference of the change in fraction of plasmonsfor the two kinds of samples was that the soft variedfaster than hard, the change of concentrations inplasmons for both hard and soft Si-SiO2 irradiatedin positive bias field were greater than that in bias-free field.The experimental results are explained from the view point of energy absorbed in form of quantization.

  12. Relaciones entre asertividad y estilos cognitivos

    OpenAIRE

    Aníbal Meza Borja

    2013-01-01

    Universitarias de nivel socio-económico alto y bajo fueron comparadas en su asertividad (general, AG, defensiva, AD; y expansiva, AE) y en su estilo cognitivo (dependencia-independencia de campo DC-IC). Las de nivel alto tuvieron mayor independencia de campo no difirieron de las de nivel bajo en AG aunque respondían diferencialmente a ciertos ítems. No difirieron en AE pero si en AD, siendo las de nivel alto más asertivas. Los estilos cognitivos y la AD correlacionaban, siendo más asertivas l...

  13. Semiosfera: pliegue entre mundo y lenguaje

    OpenAIRE

    López Cedeño, Francisco

    2014-01-01

    El hombre no puede estructurar la realidad haciendo abstracción de la lengua y de la cultura. Estas mantienen a la realidad en un movimiento continuo. La cultura es capaz de aislar este dinamismo y de ayudar al hombre a actuar porque refleja a la realidad en sí misma, la organiza ideológicamente, y hace mitos de la aventura humana. Si conociéramos los antagonismos que agitan la cultura, podríamos comprender mejor su naturaleza y su función.

  14. Synthesis and characterization of laminated Si/SiC composites

    Directory of Open Access Journals (Sweden)

    Salma M. Naga

    2013-01-01

    Full Text Available Laminated Si/SiC ceramics were synthesized from porous preforms of biogenous carbon impregnated with Si slurry at a temperature of 1500 °C for 2 h. Due to the capillarity infiltration with Si, both intrinsic micro- and macrostructure in the carbon preform were retained within the final ceramics. The SEM micrographs indicate that the final material exhibits a distinguished laminar structure with successive Si/SiC layers. The produced composites show weight gain of ≈5% after heat treatment in air at 1300 °C for 50 h. The produced bodies could be used as high temperature gas filters as indicated from the permeability results.

  15. Argentina: entre o Mercosul e a Alca

    Directory of Open Access Journals (Sweden)

    Raúl Bernal-Meza

    2001-12-01

    Full Text Available Este artigo procura mostrar que a Argentina não está numa encruzilhada na sua política externa, tendo que escolher entre Mercosul ou Alca. Ao contrário, a Argentina vê o Mercosul como um caminho que leva à Alca, afirmando uma posição que se tornou possível depois da confluência de outros fatores, como a posição brasileira frente a Alca e o modelo de integração regional proposta para o Mercosul.This article seeks to show that Argentina is not in crossroads in your foreign policy, having to choose between Mercosur and FTAA. In contrast, Argentina sees Mercosur as a way that leads to FTAA, affirming a position that become possible after a confluence of others factors, as the Brazilian position front Alca and the model of regional integration proposal for Mercosur.

  16. INTERFACE ENTRE MEMÓRIA E LEITURA

    Directory of Open Access Journals (Sweden)

    Pedro Nunes de Castro

    2008-04-01

    Full Text Available Leitura e memória são realidades que se coadunam, na medida em que são interdependentes. Esse artigo nasce a partir de uma afirmação de Ivan Izquierdo, neurologista e especialista em memória. Ele assevera que a leitura é a forma mais completa de exercitar a memória. Busco subsídios, essencialmente na Psicologia Cognitiva, para entender essa categórica afirmação. Relaciono alguns aspectos sobre o processamento de textos, e classifico as memórias conforme a função, conteúdo e tempo de duração. A partir disso, delineio a interface comum e intrínseca entre essas duas realidades.

  17. Las relaciones compositivas entre cine y arquitectura

    Directory of Open Access Journals (Sweden)

    Luis Villareal Ugarte

    2011-07-01

    Full Text Available El presente texto presenta la cinematografía y, en particular, sus técnicas de creación (construcción como un referente para la proyección de la obra arquitectónica. Se hace una lectura sobre las posibilidades que surgen en el encuentro entre estas dos disciplinas, siempre desde una perspectiva del proyecto arquitectónico, es decir, desde su concepción-composición. El texto se construyó a partir de las técnicas propias del lenguaje cinematográfico, más relacionadas con la proyección espacial arquitectónica, para ir encontrando paralelos entre ambas expresiones artísticas. Con esta intención, se ha echado mano de bibliografía que, desde una perspectiva compositiva, ayude a comprender las posibilidades que representa esta relación. Igualmente, el texto hace referencia a reconocidas obras arquitectónicas que por su misma composición (y experiencia son muestra de esta actitud creadora. Estas obras ayudan a demostrar la propuesta del autor, y el texto trata de ser una invitación para releer su arquitectura desde otra perspectiva que pueda dar pie para la creación de nuevas obras arquitectónicas. Más que expositiva, la intención principal del texto es propositiva para el lector-compositor de los nuevos espacios.

  18. Un pequeño aumento en el espaciado entre letras favorece la lectura en niños disléxicos

    OpenAIRE

    Victoria Panadero; Manuel Perea; Pablo Gómez

    2012-01-01

    Varias investigaciones recientes han mostrado que un ligero aumento del espaciado entre las letras (respecto al espaciado estándar) produce tiempos de lectura más rápidos en los niños con dislexia, así como mejoras en la comprensión de los textos. Si bien el aumento en el espaciado de las letras no “cura” la dislexia, sí permite una mejora en el proceso de lectura. Es importante remarcar que la posibilidad de modificar el espaciado entre letras se encuentra disponible en los programas de proc...

  19. Relación entre la heterogeneidad del paisaje y la riqueza de especies de flora en cuencas costeras del estado de Veracruz, México

    OpenAIRE

    Ángel G. Priego; Patricia Moreno Casasola; José Luis Palacio Prieto; Jorge López Portillo; Daniel Geissert Kientz

    2003-01-01

    La heterogeneidad del paisaje varía en el espacio dependiendo de la proporción entre polígonos y unidades tipológicas. La alta variabilidad del espacio geográfico le confiere una elevada connotación ecológica, lo cual sugiere una estrecha relación con la distribución de la biodiversidad. El objetivo de este estudio es conocer si se puede predecir la riqueza de especies a través de indicadores de variabilidad espacial. Para esclarecer esto, se exploró la relación entre heterogeneidad del paisa...

  20. As impossibilidades da “lusofonia” e as narrativas acerca do “outro e do “eu” entre Brasil e Portugal

    Directory of Open Access Journals (Sweden)

    Túlio de Souza Muniz

    2015-05-01

    Full Text Available A relação Brasil e Portugal é pautada pelo distanciamento recíproco entre dois países que tantas semelhanças guardam entre si, mas que não conseguem aproximar-se nas suas diferenças. Este ensaio visa refletir sobre esse distanciamento, a partir de uma análise da construção do estereotipo do “outro” por ambas as partes para concluir sobre as impossibilidades da “lusofonia”, um conceito que so tem operacionalidade do lado lusitano

  1. Rehabilitació del magatzem de xarxes al Moll de Pescadors : la gastronomia com a articulació entre la ciutat i la pesca

    OpenAIRE

    Roig Malaret, Agustí

    2015-01-01

    L’exercici proposa l’aproximació de la ciutat al Moll de Pescadors a partir del tractament dels diferents espais, articulats per la gastronomia. Un bar de pescadors, unes societats gastronòmiques i el restaurant d’alta cuina de la Llotja de Barcelona. Aquesta acull la confraria i una escola de cuina, creant en tot moment una contraposició entre el món pesquer i la ciutat que s’explicita al llarg del moll, culminant a l’interior de la Llotja amb un joc de volums enfrontats entre si.

  2. Educational Selection Between Public School and Private School in Galicia Elección Educacional Entre Escuela Pública y Escuela Privada en Galicia

    OpenAIRE

    Prof. María Jesús Freire; Prof. José Venancio Salcines

    1999-01-01

    Este trabajo tiene como objeto analizar la elección educativa entre escuela pública y escuela privada para los siguientes niveles educativos: infantil, primaria y secundaria en el contexto de los hogares de Galicia (España). Este artículo también analiza en que medida está relacionado el tipo de centro educativo al que asisten los niños con la renta familiar y, la educación recibida por los padres; de esta forma, esperamos aprender algo mas acerca de la desigualdad que existe entre los dos si...

  3. El liderazgo de hombres y mujeres : diferencias en estilos de liderazgo, relaciones entre estilos y predictores de variables de resultado organizacional

    OpenAIRE

    Cuadrado Guirado, Isabel; Molero Alonso, Fernando; Navas Luque, Marisol

    2003-01-01

    El objetivo de nuestro trabajo es averiguar si hombres y mujeres líderes perciben que adoptan diferentes estilos de liderazgo. Se incluyen los estilos más investigados desde la perspectiva psicosocial: «autocrático»-«democrático», «orientación a la tarea»-«orientación a las relaciones» y «transformacional»-«transaccional». Asimismo, pretendemos conocer las diferencias entre líderes de distinto sexo en dos aspectos: a) las relaciones existentes entre los comportamien...

  4. La Interacción Mutua entre Fuentes y las Aparentes Anomalías en el Fenómeno de Interferencia

    OpenAIRE

    Reinaldo Welti

    2002-01-01

    En la mayoría de los textos de física del nivel básico universitario al tratar el fenómeno de interferencia suponen que las fuentes irradian de la misma forma cualquiera sea la distancia entre ellas. En algunas situaciones esta suposición puede llevar a aparentes anomalías en la conservación de la energía. En este trabajo se muestra que estas anomalías se resuelven solamente si el fenómeno de interferencia se presenta en un contexto que tenga en cuenta las interacciones entre las fuentes y el...

  5. Relación entre producción y precios de alimentos con la subnutrición en América Latina

    OpenAIRE

    Andrés Morales Alquicira; Araceli Rendón Trejo

    2008-01-01

    Para generar un modelo explicativo se requiere conocer si existe relación entre las variables involucradas. Este trabajo tiene como objetivo ilustrar, mediante un estudio de caso, el proceso seguido para identificar y validar estadísticamente las posibles relaciones que existen entre variables. Se analiza el comportamiento de la proporción de población subnutrida en América Latina y su relación con dos variables: 1. la producción de alimentos; y 2. sus precios en los países de la región en el...

  6. Entre angústia e desamparo

    Directory of Open Access Journals (Sweden)

    Jacques André

    2001-12-01

    Full Text Available Em sua discussão, o autor diz que a angústia é o motor da análise e de seu progresso: em si mesma é abertura para os enigmas do interior. O desamparo, por sua vez, indica que a vida psíquica continua a ser vivida fora de si, na desesperada abertura para um outro que não responde. Então, na análise, se uma mobiliza, o outro paralisa. O amor (compreendido em sua parte não narcísica é "agarrar-se" aos objetos do mundo exterior, é abertura mantida para o outro e, nesse ponto, homogênea do estado de desamparo do bebê.Between anxiety and helplessness. In this paper the author states that anxiety is the engine of both analysis and its progress: in itself it is an opening to the puzzles of the interior. Helplessness, on the other hand, points out that psychic life is still being lived out of oneself, in a desperate opening to an unresponsive other. So, under the analysis point of view, while one mobilizes, the other paralyses. Love (out of its narcissistic part is "to cling" to objects of the external world, it is an opening to the other and, at that point, homogeneous to the baby's state of helplessness.

  7. Recherche sur la situation linguistique de Biarritz au XVIIIème siècle

    OpenAIRE

    Iglesias, Hector

    1996-01-01

    Version revue et corrigée Il s'agit d'un article offrant une meilleure connaissance des relations tant historiques que linguistiques, nouées au cours des siècles entre les cultures basque et occitane, notamment gasconne, dans le territoire de Biarritz. L'étude de l'onomastique bas-aturienne du territoire biarrot y est réalisée à partir, entre autres, de minutes notariales très souvent encore inexploitées. Iragan denboretako Biarritzeko egoera linguistikoa aztertzen da.

  8. SiC/SiC composites and application%SiC/SiC复合材料及其应用

    Institute of Scientific and Technical Information of China (English)

    李崇俊

    2013-01-01

    日本开发的Nicalon和Tyranno两种品牌的SiC纤维占有世界上绝对性的市场份额.SiC/SiC复合材料典型的界面层是500 nm厚的单层热解碳(PyC)涂层或多层(PyC-SiC)n涂层,在湿度燃烧环境及中高温条件下界面层的稳定性是应用研究的重点.SiC/SiC复合材料,包括CVI-SiC基体和日本开发的Tyranno hex和NITE-SiC基体等,具有耐高温、耐氧化性和耐辐射性的特点,在航空涡轮发动机部件、航天热结构部件及核聚变反应堆炉第一壁材料等方面正开展工程研制应用.%The two trademarks of Nicalon and Tyranno SiC fibers,developed in Japan,occupy the overwhelming world market.The typical interlayer in SiC/SiC composites is either a single pyrolytic carbon (PyC) coating with a thickness of 500nm or multilayered (PyC-SiC)n coatings.The fiber/matrix interlayer stabilities in SiC/SiC composites are a key research topic for applications in the wet combustion environment with high temperature.The CVI-SiC matrix based SiC/SiC composites,as well as Japan produced Tyranno-hex composites and NITESiC matrix,perform the characteristics of high temperature,anti-oxidation and anti-irradiation,and are having been progressed into engineering application in the fields of aircraft turbine engine components,aerospace thermostructural parts and fusion reactor thermo-structural materials.

  9. Entre dos fuegos: el arte-ciencia y la guerra entre ciencia y humanidades

    OpenAIRE

    Galanter, Philip

    2011-01-01

    Peer reviewed Hi ha una divisió fonamental d'ordre filosòfic entre la cultura moderna de la ciència i la cultura postmoderna de les humanitats. Aquest distanciament cultural és, entre altres coses, la causa subjacent que explica la poca acceptació de l'art científic i de l'art tecnològic en el món de l'art majoritari. No obstant això, en les dues últimes dècades, l'estudi de la complexitat ha comportat una revolució en les ciències. En aquest treball es postula la viabilitat d'ampliar el p...

  10. Entre Pauline Kergomard et Maria Montessori

    OpenAIRE

    Moussy, Bernadette

    2007-01-01

    Au XIXe siècle les références concernant l’éducation de la petite enfance ont pris deux orientations différentes. L’une donne comme modèle la mère éducatrice. Dans l’autre référence,  l’éducatrice très respectueuse de la dynamique de l’enfant, intervient le moins possible. Deux femmes pédagogues sont représentatives de ces courants : D’une part, Pauline Kergomard (inspectrice des écoles maternelles, 1838-1925) auteur de « L’éducation maternelle à l’école » présente comme référence « la mère ...

  11. Methods of radiation effects evaluation of SiC/SiC composite and SiC fibers

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, G.E.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-03-01

    This report covers material presented at the IEA/Jupiter Joint International Workshop on SiC/SiC Composites for Fusion structural Applications held in conjunction with ICFRM-8, Sendai, Japan, Oct. 23--24, 1997. Several methods for radiation effects evaluation of SiC fibers and fiber-reinforced SiC/SiC composite are presented.

  12. Louisiana Story, entre nature et cultures

    Directory of Open Access Journals (Sweden)

    Christine Louveau de la Guigneraye

    2001-12-01

    Full Text Available Dans Louisiana Story, Robert Flaherty a choisi l'opulente nature louisianaise comme lieu de rencontre entre deux cultures: une culture industrielle anglophone et une culture rurale francophone. Ce film, qui est commandé et financé par la compagnie pétrolière Standard Oil devait à l'origine montrer les difficultés et les dangers de l'extraction pétrolière pour ses équipes tout en les mettant en scène dans une réalisation destinée au grand public. Le problème posé à Flaherty était que de telles manœuvres étaient souterraines, qu'elles échappaient à l'objectif de la caméra. Après avoir parcouru des milliers de kilomètres aux Etats-Unis à la recherche de l'inspiration, son choix se porta sur le pays des Acadiens de Louisiane où il fut marqué par l'image d'une plate-forme se déplaçant par voie d'eau sur l'un des multiples bayous de cette région. Ce lieu lui permettait de mêler et de confronter dans la même image la modernité des derricks et une nature sauvage, une population étrange par ses traditions et son langage à une population ouvrière plus typiquement américaine. Louisiana Story reste un film étrange et ambigu. Les hommes y apparaissent secondaires dominés par le gigantisme des équipements pétroliers et la grandeur de la nature. Il semble que lors du tournage Flaherty ait été fasciné par la faune et la flore au détriment du scénario qui était la rencontre entre deux cultures à travers les découvertes et les liens d'amitié d'un petit garçon cajun.

  13. Coocurrencia entre ansiedad y autismo: Las hipótesis del error social y de la carga alostática

    OpenAIRE

    Paula Pérez, Isabel, 1970-

    2013-01-01

    Introducción. El concepto de comorbilidad en trastornos del neurodesarrollo como el autismo resulta, en ocasiones, ambiguo. La coocurrencia entre ansiedad y autismo es clínicamente signifi cativa; sin embargo, no siempre es fácil diferenciar si se trata de una comorbilidad"real", donde las dos condiciones comórbidas son fenotípica y etiológicamente idénticas a lo que supondría dicha ansiedad en personas con un desarrollo neurotípico; si se trata de una ansiedad fenotípicamente alterada por lo...

  14. Joining of SiC ceramics and SiC/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Rabin, B.H. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1995-08-01

    This project has successfully developed a practical and reliable method for fabricating SiC ceramic-ceramic joints. This joining method has the potential to facilitate the use of SiC-based ceramics in a variety of elevated temperature fossil energy applications. The technique is based on a reaction bonding approach that provides joint interlayers compatible with SiC, and excellent joint mechanical properties at temperatures exceeding 1000{degrees}C. Recent efforts have focused on transferring the joining technology to industry. Several industrial partners have been identified and collaborative research projects are in progress. Investigations are focusing on applying the joining method to sintered a-SiC and fiber-reinforced SiC/SiC composites for use in applications such as heat exchangers, radiant burners and gas turbine components.

  15. Joining of SiC ceramics and SiC/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Rabin, B.H. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1996-08-01

    This project has successfully developed a practical and reliable method for fabricating SiC ceramic-ceramic joints. This joining method will permit the use of SiC-based ceramics in a variety of elevated temperature fossil energy applications. The technique is based on a reaction bonding approach that provides joint interlayers compatible with SiC, and excellent joint mechanical properties at temperatures exceeding 1000{degrees}C. Recent emphasis has been given to technology transfer activities, and several collaborative research efforts are in progress. Investigations are focusing on applying the joining method to sintered {alpha}-SiC and fiber-reinforced SiC/SiC composites for use in applications such as heat exchangers, radiant burners and gas turbine components.

  16. Al versus Si competition in FeSiAl alloys

    Energy Technology Data Exchange (ETDEWEB)

    Legarra, E. [Dpto. Electricidad y Electronica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco (UPV/EHU), CP 644, 48080 Bilbao (Spain)], E-mail: estibaliz.legarra@ehu.es; Apinaniz, E. [Dpto. Fisica Aplicada I, Escuela de Ingenieria Tecnica Superior, Universidad del Pais Vasco, Alameda de Urquijo s/n 48013 Bilbao (Spain); Plazaola, F. [Dpto. Electricidad y Electronica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco (UPV/EHU), CP 644, 48080 Bilbao (Spain); Jimenez, J.A. [Centro Nacional de Investigaciones Metalurgicas (CENIM), Avda. Gregorio del amo 8, 28040 Madrid (Spain); Pierna, A.R. [Chemical Engineering and Environmental Department, UPV/EHU, Box 1379, 20008 San Sebastian (Spain)

    2008-10-15

    In FeSiAl alloys, when Si substitutes for Al, important changes take place in the magnetism as well as in the structural properties. Alloys in the two composition series Fe{sub 75}Al{sub 25-x}Si{sub x} (x=0, 7.5, 12.5, 17.5, 25) and Fe{sub 70}Al{sub 30-x}Si{sub x} (x=0, 9, 15, 21, 30) were prepared by induction melting; afterwards they were crushed and then annealed in order to recover the DO{sub 3} stable phase. The deformed FeAl samples show larger lattice parameters than the ordered ones; however, this difference ({delta}a) decreases when Si substitutes for Al until it becomes zero (i.e. until the ordered samples and the deformed ones have the same lattice parameters). This trend is the same for both sample series and does not depend on the Fe content of the alloy. However, the magnetization has a different behaviour depending on the Fe content. For deformed Fe{sub 75}Al{sub 25-x}Si{sub x} alloys the saturation magnetization decreases with increasing Si content while for Fe{sub 70}Al{sub 30-x}Si{sub x} deformed alloys the saturation magnetization has a plateau in which the saturation magnetization values do not vary.

  17. Stress and stress monitoring in SiC-Si heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Pezoldt, Joerg; Niebelschuetz, Florentina; Cimalla, Volker; Stauden, Thomas [FG Nanotechnology, Institute of Micro- and Nanotechnologies, TU Ilmenau, Postfach 100565, 98684 Ilmenau (Germany); Nader, Richard; Masri, Pierre [Groupe d' Etudes des Semiconducteurs, CNRS cc074, UMR 5650, Universite Montpellier 2, Place E. Bataillon, 34095 Montpellier Cedex 5 (France); Zgheib, Charbel [Department of Electrical, Computer Communication Engineering, Notre Dame University, 5725 Deir El Kamar (Lebanon)

    2008-04-15

    Infrared ellipsometry is a valuable tool to investigate the average stress and the stress distribution in thin silicon carbide layers grown on silicon as well as to monitor the changes in the stress state during device processing. It was obtained that low temperature carbonization in combination with low temperature epitaxial growth led to a compressive stress component in the SiC-Si interface region, whereas the average stress state is tensile. Ge incorporation in the interface lowered the tensile residual stress component. Metallization of SiC increases the tensile stress in the SiC on Si. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Advanced SiC fibers and SiC/SiC composites toward industrialization

    International Nuclear Information System (INIS)

    In order to establish the industrialization basis of advanced SiC fibers and SiC/SiC composites to be used in nuclear fusion reactors, R and D of Tyranno-SA grade fibers (Cef-NITETM) and NITE-SiC/SiC with sufficient quality control has been carried out. The important elements in this effort are fiber structure control and matrix density and homogeneity control. From the continuous heat treatments of pre-crystallized SiC fibers, the improved uniformity of grain size for radial position in 7-10 μm diameter SiC fibers has been confirmed with the fiber strength over 2.0 GPa. In order to establish stable mass production of NITE-SiC/SiC (Cera-NITETM), with sufficient quality control, efforts on production of mid-products, such as green sheets, prepreg sheets and preforms, have been extensively carried out. The important elements were to improve the homogeneity and density of preform so that the following sintering process has been modified for improving structure control.

  19. Acidentes de trabalho ocorridos entre adolescentes

    Directory of Open Access Journals (Sweden)

    Aline Alcântara Pimenta

    2013-01-01

    Full Text Available Este estudio tuvo como objetivo identificar los accidentes de trabajo producidos entre los adolescentes en una fundación de educación para el trabajo. Estudio descriptivo, cuantitativo que investigó 117 adolescentes trabajadores a través de un cuestionario multidimensional. De los encuestados, el 72,6% eran mujeres, el 80,3% tenían 15 años, el 60% eran pardos y el 62,4% no trabajaba anteriormente. Las actividades más populares realizadas fueron las siguientes: Recepcionista (46,2% y auxiliar administrativo (37,6%. Sufrieron accidentes en el trabajo o antes de llegar a este el 11% de los encuestados, de los cuales 76,9% eran típicos y se produjeron en la tarde (61,5%. Las piernas y los pies fueron los miembros mas heridos (46,2%, seguido por abrasiones y lesiones graves (30,8%. El trabajo de niños y adolescentes pueden presentar agravios, que se clasifican como accidentes. El enfrentamiento de este problema no puede ser pensado sólo en términos de vigilancia de los lugares de trabajo y de las políticas dirigidas a la salud del trabajador; hay una necesidad de una mayor transformación en la estructura de la sociedad, de modo que el trabajo perjudique la salud.

  20. Heterogeneidade entre Leitores Julgados Competentes pelas Professoras

    Directory of Open Access Journals (Sweden)

    Pinheiro Ângela Maria Vieira

    2001-01-01

    Full Text Available O desempenho de leitura de um grupo de crianças de quarta série, julgadas pela professora como leitoras com desenvolvimento normal, foi investigado. Uma medida de desempenho deficiente/competente - baixos níveis de erros e tempos de reação rápidos para as respostas corretas para a leitura em voz alta de palavras reais (variando em familiaridade, regularidade e comprimento e não-palaras (com a mesma estrutura ortográfica das palavras reais e variando em comprimento - foi obtida com o objetivo de estabelecer uma definição de desempenho eficiente de leitura que, por sua vez, serviu de base para a identificação de deficiências, em crianças do mesmo grupo, cujos resultados situaram-se fora da amplitude estabelecida como normal. Dentre esses participantes houve um exemplo de dislexia fonológica e vários casos apresentando danos que afetaram ambos os processos, lexical e fonológico, com uma tendência para o padrão fonológico. A discrepância entre a avaliação da professora e a avaliação cognitiva de leitura conduzida é discutida.

  1. EUTANASIA, ENTRE LA VIDA Y LA MUERTE ¿QUIÉN Y QUÉ LA DECIDE?

    OpenAIRE

    Araque, Olga Ligia

    2014-01-01

    La eutanasia significa entre varios aspectos la inducción de la muerte sin dolor en interés del destinatario y supone una reducción en laduración de la vida de un enfermo terminal.El daño que se infringe al destinatario es la reducción del tiempo de vida; si el enfermo no es terminal entonces no es caso de eutanasia.Esta se fundamenta en el principio de que nadie puede ser cruel con los demás. La idea más básica de la eutanasia está relacionada con labenevolencia. La vida humana es un valor p...

  2. Entre a Filosofia e a Ciência: Merleau-Ponty e a Psicologia

    Directory of Open Access Journals (Sweden)

    Danilo Saretta Verissimo

    2007-12-01

    Full Text Available Merleau-Ponty abordou um problema da tradição filosófica que se agudizou após o desenvolvimento das ciências humanas: a discordância entre a visão que o homem pode ter de si mesmo pela reflexão ou consciência e aquela que se obtém relacionando suas condutas às condições externas das quais elas dependem. Merleau-Ponty procurou resolver essa discordância à luz das próprias experiências das ciências, particularmente, da psicologia. Segundo ele, essas experiências demandam uma revisão da ontologia moderna. Neste contexto, no presente artigo, abordamos algumas facetas do diálogo estabelecido por Merleau-Ponty com a psicologia. Apresentamos uma leitura de questões tratadas, sobretudo em seus trabalhos iniciais.

  3. Relación entre síndrome de burnout, estrategias de afrontamiento y engagement

    Directory of Open Access Journals (Sweden)

    Paula Andrea Montoya Zuluaga

    2012-01-01

    Full Text Available Este artículo tiene como finalidad analizar, a partir de las teorías existentes, la relación entre las estrategias de afrontamiento, el síndrome de burnout y el engagement. El síndrome de burnout si bien se desarrolla en un contexto organizacional, es individual y ello ya implica la existencia de factores de riesgo que llegan a activarse (ya sea para posibilitar su aparición por las estrategias de afrontamiento que se asumen o evitar su desarrollo, cuando hay engagement en contextos laborales donde hay presencia de alta carga laboral, bajas recompensas por el oficio llevado a cabo y ambientes laborales en los que no se posibilita la participación para la toma de decisiones.

  4. Análisis de la relación entre contabilidad y fiscalidad en Colombia

    Directory of Open Access Journals (Sweden)

    Ernesto María Sierra González

    2008-06-01

    Full Text Available La relación entre contabilidad y fiscalidad ha sido una tradición en Colombia, pues es notable la influencia ejercida por las instituciones de carácter público encargadas del control impositivo, en la normativa sobre la cual descansa la práctica contable del país. Si bien se han hecho esfuerzos por separar las dos dimensiones, aún hoy estas permanecen. Con la propuesta de adoptar Normas Internacionales de Contabilidad (NIC, se hace necesario separar las dos esferas. Pero las diferencias en los métodos de cálculo y valoración afectan los resultados de la empresa y por tanto su efecto impositivo. Se trata pues del análisis de esta problemática en aras de garantizar los niveles de recaudo y evitar distorsiones en el mercado.

  5. CIUDADANÍA FISCAL Y NUEVAS FORMAS DE RELACIÓN ENTRE CONTRIBUYENTES Y ADMINISTRACIÓN TRIBUTARIA

    OpenAIRE

    Alejandro M. Estévez; Susana C. Esper

    2009-01-01

    Usualmente, el cumplimiento fiscal ha sido explicado por el riesgo de la coerción. Este artículo analiza la nueva orientación de las administraciones tributarias, a fin de comprender cómo este hecho puede alentar la cultura tributaria de las sociedades, a través de la autorregulación y el cumplimiento voluntario. Aunque la mejora de la relación entre administración tributaria y el contribuyente no asegura en su totalidad, ni es la única manera para lograr el cumplimiento tributario, si consti...

  6. Perfil psicológico de los jugadores profesionales de balonmano y diferencias entre puestos específicos

    OpenAIRE

    Aurelio Olmedilla; Enrique Ortega; Enrique Garcés de los Fayos; Lucía Abenza; Amador Blas; María Laguna

    2015-01-01

    En este estudio se pretende determinar las características psicológicas para el rendimiento deportivo de los jugadores de balonmano de alto nivel y establecer si existen diferencias entre el perfil psicológico de estos jugadores en función del puesto táctico ocupado. La muestra estuvo compuesta por 80 jugadores profesionales de balonmano, con una edad media de 24.83 (± 5.21) a˜nos. Respecto al puesto de juego, el 30% jugaban de extremo, el 25% de lateral, el 16.3% de central, el 18.7% de pivo...

  7. Paso a paso con Beauvoir en el debate entre materialismo histórico, psicoanálisis y feminismo

    OpenAIRE

    Soza Rossi, Paula V.; Rodríguez Durán, Adriana

    2008-01-01

    Releyendo El segundo sexo de Simone de Beauvoir, nos interesó retomar el debate entre materialismo histórico, psicoanálisis y feminismo a fin de reflexionar sobre sus aportes y las derivaciones actuales de lo inicialmente planteado por la autora. Nuestra inquietud respecto a esa articulación es si establece una continuidad con trabajos anteriores donde ya se hubiera intentado revisar los dualismos y el sesgo de género, ambos presentes en las teorizaciones de nuestras disciplinas de origen: Ps...

  8. Relación entre la inteligencia emocional y el rendimiento académico en segundo de primaria

    OpenAIRE

    Nieto-Pedescoll, Anna Maria

    2015-01-01

    La educación emocional es una de las grandes olvidadas actualmente en los centros educativos, sin embargo es uno de los ámbitos que favorece el desarrollo integral de las personas. Este trabajo tiene como objetivo proponer un plan de intervención para fomentar la inteligencia emocional, para aquellos alumnos/as que tengan dificultades y para mantenerla en los que la tienen desarrollada. Pero antes queremos analizar si hay una relación entre la inteligencia emocional y el rendimiento académico...

  9. Development and validation of a method for the determination of valproic acid in pharmaceutical formulations by high performance liquid chromatography with diode array detection (HPLC-DAD / Desenvolvimento e validação de um método para a determinação de ácido valpróico em formulações farmacêuticas por cromatografia líquida de alta eficiência acoplada com detector de conjunto de fotodiodos

    Directory of Open Access Journals (Sweden)

    Paulo Ricardo de Souza e Souza

    2013-02-01

    Full Text Available Valproic acid (VA is used as an anticonvulsant and is used in the treatment of bipolar disorder and depression. The offi cial analytical method for this drug in the compendia is gas chromatography, which is unavailable in many quality control laboratories. Here, we report a validated alternative method using high performance liquid chromatography with diode array detection (HPLC-DAD. The optimized parameters and conditions were as follows: C18 column (5 μm; 250 x 4 mm d.i.; fl ow 1.0 mL.min-1; wavelength: 210 nm; mobile phase: 55% acetonitrile (ACN in water containing 0.05% v/v trifl uoroacetic acid (TFA (v/v. The analytical parameters that were validated included the selectivity and matrix effects, linearity, repeatability and intermediate, precision, accuracy, recovery and robustness. This method identifi es VA unambiguously. In validation, the following results were obtained: good linearity in concentrations between 0.7 and 1.3 mg.mL-1 (r2 = 0.9998, relative standard deviations (RSDs of 0.68% for repeatability and 1.23% for intermediate precision, a recovery of 99.42 to 101.55% (RSD 0.14 to 0.74% and an accuracy of 100.68% (RSD = 0.79%. This method is robust to small variations in procedure. ------------------------------------------------------------------------------------- O ácido valpróico (VA é utilizado como anticonvulsivante e também na terapêutica da desordem bipolar e depressão. O método de análise deste medicamento nos compêndios ofi ciais é por cromatografi a gasosa e muitos laboratórios ofi ciais de controle de qualidade não possuem tal equipamento. A proposta deste estudo foi desenvolver e validar um método analítico por cromatografi a líquida de alta efi ciência acoplada com detector de conjunto de fotodiodos para a análise deste fármaco. Os parâmetros e condições otimizados foram: coluna C18 (5 μm; 250 x 4 mm d.i., fl uxo de 1,0 mL min-1, comprimento de onda 210 nm, fase móvel 55% ACN e 45

  10. Development and validation of a method for detection and quantification of ochratoxin A in green coffee using liquid chromatography coupled to mass spectrometry Desenvolvimento e validação de metodologia na detecção e na quantificação de Ocratoxina A no café verde utilizando cromatografia líquida acoplada à espectrometria de massas

    Directory of Open Access Journals (Sweden)

    Raquel Duarte da Costa Cunha Bandeira

    2012-12-01

    Full Text Available A method using Liquid Chromatography Tanden Mass Spectrometry (LC-MS/MS with matrix-matched calibration curve was developed and validated for determining ochratoxin A (OTA in green coffee. Linearity was found between 3.0 and 23.0 ng.g-1. Mean recoveries ranged between 90.45% and 108.81%; the relative standard deviation under repeatability and intermediate precision conditions ranged from 5.39% to 9.94% and from 2.20% to 14.34%, respectively. The limits of detection and quantification were 1.2 ng.g-1 and 3.0 ng.g-¹, respectively. The method developed was suitable and contributed to the field of mycotoxin analysis, and it will be used for future production of the Certified Reference Material (CRM for OTA in coffee.Um método utilizando Cromatografia Líquida de Alta Eficiência-Espectrometria de Massas Sequencial (CLAE-EM/EM com curva de calibração em matriz foi desenvolvido e validado para a determinação de ocratoxina A (OTA em café verde. A linearidade foi demonstrada entre 3,0 e 23,0 ng.g-1. As recuperações médias variaram entre 90,45% e 108,81%; o desvio padrão relativo sob condições de repetitividade e precisão intermediária foram de 5,39% e 9,94% e de 2,20% e 14,34%, respectivamente. Os limites de detecção e quantificação foram 1,2 ng.g-1 e 3,0 ng.g-, respectivamente. O método desenvolvido foi adequado, contribuiu para o campo de análises em micotoxinas e será usado para a futura produção de Material de Referência Certificado (MRC para OTA em café.

  11. Max Weber entre liberalismo y republicanismo

    Directory of Open Access Journals (Sweden)

    Villacañas Berlanga, José Luis

    2005-12-01

    Full Text Available This article attempts to analyze the differences between social democracy and political democracy as modern processes, as these were understood by Max Weber. The archetype of modernity resides, from this point of view, in a convergence of both processes, as occurred in countries like the USA and Great Britain. Weber's diagnosis is that, whereas social democracy can be organized around liberal arguments, political democracy cannot advance without republican concepts like those of virtue, rigour, responsability and representation. For Weber, these values could only become present in Germany thanks to an adequate and democratic reception of Nietzsche, and in some way this reception could make sense of the former's work.

    Este artículo pretende analizar las diferencias entre democracia social y democracia política como procesos modernos, tal y como fueron comprendidos por Max Weber. Lo arquetípico de la modernidad reside, desde este punto de vista, en una convergencia de ambos procesos, tal y como se dio en países como USA y Gran Bretaña. El diagnóstico de Weber es que, mientras la democracia social puede organizarse sobre argumentos liberales, la democracia política no puede avanzar sin conceptos republicanos como el de virtud, rigor, responsabilidad y representación. Para Weber, estos valores sólo podrían hacerse presentes en Alemania a partir de una recepción adecuada y democrática de Nietzsche y en cierto modo esta recepción daría sentido a su obra.

  12. Biomorphous SiSiC/Al-Si ceramic composites manufactured by squeeze casting: microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Zollfrank, C.; Travitzky, N.; Sieber, H.; Greil, P. [Department of Materials Science, Glass and Ceramics, University of Erlangen-Nuernberg (Germany); Selchert, T. [Advanced Ceramics Group, Technical University of Hamburg-Harburg (Germany)

    2005-08-01

    SiSiC/Al-Si composites were fabricated by pressure-assisted infiltration of an Al-Si alloy into porous biocarbon preforms derived from the rattan palm. Al-Si alloy was found in the pore channels of the biomorphous SiSiC preform, whereas SiC and carbon were present in the struts. The formation of a detrimental Al{sub 4}C{sub 3}-phase was not observed in the composites. A bending strength of 200 MPa was measured. The fractured surfaces showed pull-out of the Al-alloy. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  13. Thermal stability of Nb-Si-N and Ta-Si-N as diffusion barriers between Cu and Si

    International Nuclear Information System (INIS)

    In this study, Nb-Si-N and Ta-Si-N films were deposited on (100)Si wafers using a reactive sputtering technique and their thermal stability indispensable for a barrier metal against Cu was investigated using sheet resistance measurement, X-ray diffraction, and Auger electron spectroscopy depth profiling. The N2/Ar gas flow ratio for the sputter deposition of the Nb-Si-N and Ta-Si-N films with the highest thermal stability were found to be 5 % and 15 %, respectively. The Nb-Si-N film failed at 700 .deg. C, while the Ta-Si-N film failed at 900 .deg. C. the failure mechanism of the Nb-Si-N was found to be as follows : Cu atoms move to the Nb-Si-N/Si interface through the Nb-Si-N film and react with Si atoms in the Si substrate resulting in the formation of Cu3Si at the Nb-Si-N/Si interface. Also the failure mechanism of Ta-Si-N was found to be nearly the same as that of Nb-Si-N

  14. La sociologie clinique entre psychanalyse et socioanalyse

    Directory of Open Access Journals (Sweden)

    Vincent de Gaulejac

    2008-04-01

    Full Text Available L'introduction de la démarche clinique en sociologie conduit à réinterroger les différences et les complémentarités entre la psychanalyse et la sociologie sur trois points : leur façon d'appréhender la question de l'inconscient; le poids respectif des déterminations psychiques et sociales, le travail qu'un sujet peut effectuer sur son histoire pour en modifier le cours. Ces questions ont été l'objet de nombreux débats. Le présent article met en perspective les positions de Sigmund Freud et de Pierre Bourdieu. L'un et l'autre incarnent et défendent des points de vue théoriques qui articulent une théorie de l'homme en société étayée sur une pratique de changement. Confrontation intéressante dans la mesure où les postulats de départ de ces deux auteurs sont très éloignés. Sigmund Freud cherche la clé explicative des comportements humains du côté du registre intra psychique, alors que Pierre Bourdieu la pose du côté de l'intériorisation des structures sociales. Pourtant à partir de prémisses différents ils se rejoignent sur bien des points. Ces convergences permettent de s'appuyer sur leurs approches pour définir les contours d'une méthodologie qui s'inspire tout à la fois de la psychanalyse et de la socioanalyse.Clinical sociology between psychoanalysis and socioanalysisThe introduction of the clinical approach in sociology lead us to reconsider the differencies and complementarities between psychoanalysis and sociology on three aspects: their way of taking into account the unconscious; the relative weight of social and psychic predeterminations; the work that can be done by somebody on his/her own history in order to modify its course. Those questions have been largely debated. The purpose of this article is to compare on those topics the positions of Sigmund Freud and Pierre Bourdieu. Both develop theories which include a conception of man in society supported by a change practice. The interest of this

  15. Diferencias de personalidad entre matutinos y vespertinos

    Directory of Open Access Journals (Sweden)

    Virginia Dresch

    2005-01-01

    Full Text Available El objetivo de este estudio era determinar si los sujetos con distinta tipología circadiana (matutinidad-vespertinidad tenían un perfil de personalidad diferencial, trascendiendo el intento de relacionar la tipología circadiana con variables de personalidad aisladas y más generales, como Extraversión-Introversión. La investigación se llevó a cabo con 804 participantes, universitarios de una universidad del sur de Brasil (Novo Hamburgo-RS/BR de 33 carreras distintas, utilizándose el MIPS Inventario de Estilos de Personalidad de Millon (Millon, 1994 y la CS Escala Compuesta (Smith, Reilly y Midkiff, 1989 como medida de los estilos de personalidad y cronotipos, respectivamente. Los resultados apuntaron a un perfil de personalidad más deseable socialmente para los matutinos (mayor puntuación en las escalas Expansión, Sistematización y Conformismo, mientras que los vespertinos se caracterizaron por estar menos adaptados a su entorno (mayor puntuación en las escalas Preservación, Innovación, Indecisión, Discrepancia y Descontento

  16. Relaciones entre asertividad y estilos cognitivos

    Directory of Open Access Journals (Sweden)

    Aníbal Meza Borja

    2013-09-01

    Full Text Available Universitarias de nivel socio-económico alto y bajo fueron comparadas en su asertividad (general, AG, defensiva, AD; y expansiva, AE y en su estilo cognitivo (dependencia-independencia de campo DC-IC. Las de nivel alto tuvieron mayor independencia de campo no difirieron de las de nivel bajo en AG aunque respondían diferencialmente a ciertos ítems. No difirieron en AE pero si en AD, siendo las de nivel alto más asertivas. Los estilos cognitivos y la AD correlacionaban, siendo más asertivas las mujeres con independencia de campo. Two female samples from high (HS and low (LS social-economic level were evaluated in Assertiveness (General GA, Defensive DA and Expansive EA and in Cognitive Styles (Field Depedence-Independence FD-FI. Both samples differed on cognitive styles, being HS more field independent; both samples did not differed cuantitatively on GA but it could be noted some difference in the kind of assertiveness items to which they responded diferently. No difference was observed on EA but significant differences were found on DA, being HS more assertive.

  17. Low loss Si(3)N(4)-SiO(2) optical waveguides on Si.

    Science.gov (United States)

    Henry, C H; Kazarinov, R F; Lee, H J; Orlowsky, K J; Katz, L E

    1987-07-01

    We have developed an optical integrated circuit waveguide technology based on conventional Si processing. We demonstrate waveguide losses of <0.3 dB/cm in the 1.3-1.6-microm wavelength range. We use a high refractive-index core of Si(3)N(4) surrounded by SiO(2) cladding layers, which provides a highly confined optical mode adequate for butt coupling to channel substrate buried heterostructure lasers. We report the first IR transmission experiments in these waveguides and find two absorption peaks associated with H in SiO(2) and Si(3)N(4) layers at 1.40 and 1.52 microm, respectively. The peak absorptions are 2.2 and 1.2 dB/cm, respectively, and these peaks can be largely removed by annealing at 1100-1200 degrees C. PMID:20489931

  18. CONSTRUÇÃO SOCIAL DE SENTIDOS SOBRE A RAVIDEZMATERNIDADE ENTRE ADOLESCENTES

    Directory of Open Access Journals (Sweden)

    Nayara Bueno de Araujo

    2015-01-01

    Full Text Available Se buscó comprehender la construcción social de sentidos sobre embarazo-maternidad entre adolescentes embarazadas. Estudio explicativo, realizado en 2014, con 12 adolescentes, por medio de entrevista individual y grupal, observación del contexto local, consulta al documentos y preceptos de Análisis de Discurso Crítica de Fairclough. Se encontró el sentido de compatibilidad entre el embarazo y adolescencia y de contraposición al discurso dominante de embarazo como un problema. El evento respondía al que las adolescentes proyectaban para si, en uno contexto restringido de oportunidades sociales. Lo valoran con base en un ideal social de maternidad y de constitución familiar, prebendo reconocimiento social, comprobación de feminidad y mayor poder y autonomía. Sin embargo, esas ganancias se muestran atravesados por dificultades percibidas, como enfrentar el juicio familiar y el “doloroso” parto. La comprensión contextualizada de estos sentidos y su contenido social y ideológico es esencial al desenvolvimiento de mayor grado de autonomía-responsabilidad de adolescentes.

  19. Inteligência emocional: validade discriminante entre MSCEIT e 16 PF

    Directory of Open Access Journals (Sweden)

    Marilda Aparecida Dantas

    2006-04-01

    Full Text Available O objetivo do presente estudo foi investigar evidências de validade discriminante do Mayer Salovey Caruso Emotional Intelligence Test (MSCEIT, comparando-o com os 16 Fatores de Personalidade. O construto de inteligência emocional tem sido definido como a capacidade de perceber, entender e usar precisamente as emoções em si e em relação aos outros, bem como gerenciá-las para facilitar os processos cognitivos e promover o crescimento pessoal e intelectual. Participaram 270 universitários de diferentes cursos -Psicologia, Educação Física, Matemática e Biologia, sendo utilizados o MSCEIT e o 16 PF em aplicação coletiva. Os resultados indicaram correlações significativas baixas positivas e negativas entre IE e personalidade, tais como; Extroversão (r = 0,125*, Brandura (r = 0,253**, Rigidez de Pensamento (r = -0,193**. A análise dos resultados indica que não houve equivalência entre construtos de inteligência emocional e personalidade, embora algumas dimensões deste último possam contribuir para um adequado desempenho em IE.

  20. CORRELATOS ENTRE BIENESTAR SUBJETIVO Y REGULACIÓN EMOCIONAL DEL ENOJO: DIFERENCIAS POR SEXO

    Directory of Open Access Journals (Sweden)

    Magali Martínez Pérez

    2014-01-01

    Full Text Available Las experiencias emocionales negativas se asocian con el bienestar subjetivo, pero se ignora si la manera de regularlas se relaciona con los reportes de bienestar. El presente estudio exploró la asociación entre el bienestar percibido y ciertas variables culturales (premisas histórico-socio-culturales e individuales (automonitoreo, estrategias y autoeficacia involucradas en la regulación del en ojo, así como las posibles diferencias sexuales. Participaron 220 residentes que respondieron voluntariamente una batería de pruebas. Se encontró que las creencias culturales y el uso de estrategias que disminuyen la intensidad del enojo se asocian positivamente con el bienestar con amigos y trabajo, y que hay más similitudes que diferencias entre hombres y mujeres en las variables evaluadas. Los hallazgos señalan la importancia de regular apropiadamente emociones negativas como el enojo, a fin de incrementar el bienestar subjetivo de hombres y mujeres.

  1. Fabrication and evaluation of propagation loss of Si/SiGe/Si photonic-wire waveguides for Si based optical modulator

    International Nuclear Information System (INIS)

    We have characterized photonic-wire waveguides with Si/SiGe/Si heterostructure ribs for Si-based optical modulators. The Si (80 nm)/Si0.72Ge0.28 (40 nm) layers grown on Si-on-insulator by molecular beam epitaxy for optical modulators were evaluated by in-situ reflection high-energy electron diffraction, atomic force microscope, X-ray diffraction and Raman spectroscopy, exhibiting that the fully-strained highly-crystalline SiGe layer was obtained. We have evaluated the propagation loss of the Si/strained SiGe/Si photonic-wire waveguides. The wavelength dependence of the propagation loss exhibits the bandgap narrowing of the strained Si0.72Ge0.28, while the optical absorption of the strained Si0.72Ge0.28 is not significant for the optical modulator application at 1.55-μm wavelength. - Highlights: • We have characterized photonic-wire waveguides with Si/SiGe/Si heterostructure ribs. • The Si/Si0.72Ge0.28 grown on Si-on-insulator were evaluated to be fully strained. • We have fabricated and evaluated the Si/strained SiGe/Si photonic-wire waveguides. • The wavelength dependence exhibits bandgap narrowing of the strained Si0.72Ge0.28. • Optical absorption of the SiGe is not significant for optical modulators at 1.55 μm

  2. Premisas socioculturales y violencia en la pareja: diferencias y semejanzas entre hombres y mujeres

    Directory of Open Access Journals (Sweden)

    José Moral de la Rubia

    2013-01-01

    Full Text Available Esta investigación tuvo como objetivos: 1 contrastar diferencias entre hom- bres y mujeres en el conformismo hacia premisas socioculturales y en la frecuencia autorreportada de violencia en la pareja, y 2 estudiar la relación entre ambas variables. Los cuestionarios de Premisas Histórico-Sociocultu- rales (Díaz-Guerrero, 2003 y Violencia en la Pareja (Vargas, 2008 fueron aplicados a una muestra no probabilística de 223 mujeres y 177 hombres con pareja heterosexual; 48.5% estaban casados o unión libre y 51.5% eran novios. Se observó mayor machismo y consentimiento con los aspectos tradiciona- les de género en los hombres. Los promedios de violencia ejercida fueron equivalentes entre ambos sexos. Los hombres reportaron recibir significati- vamente más violencia de sus parejas. En el hombre la violencia femenina, sobre todo por aspectos de machismo masculino, genera reacción violenta, especialmente si hay mayor consentimiento con aspectos tradicionales de género (justificación ideológica. En mujeres la violencia masculina produce una reacción violenta con menor frecuencia, pero su respuesta a la misma genera el círculo de violencia, en el cual los valores machistas de la mujer contribuyen a crear situaciones de conflicto. Así la cultura machista genera violencia. Se sugiere persistir en el cambio de valores para la prevención de la violencia en la pareja.

  3. Asociación entre enfermedad cardiovascular y anticuerpos contra Chlamydia pneumoniae

    Directory of Open Access Journals (Sweden)

    García-Elorriaga Guadalupe de los A

    2002-01-01

    Full Text Available Objetivo. Precisar si existe asociación entre enfermedad cardiovascular (ECV y anticuerpos contra Chlamydia en población mexicana. Material y métodos. Estudio transversal, realizado en la Unidad de Investigación en Inmunología e Infectología -Hospital de Infectología del Centro Médico Nacional La Raza (CMNR- y en el Servicio de Cirugía Cardiovascular y Asistencia Circulatoria, del Hospital General del CMNR, Instituto Mexicano del Seguro Social (IMSS, de agosto de 1998 a abril de 2000. Se determinaron anticuerpos IgG e IgM contra C. psittaci, C. trachomatis y C. pneumoniae mediante microinmunofluorescencia, en suero de 70 pacientes con ECV hospitalizados en el CMNR, mayores de 30 años, de uno u otro sexo, y se compararon con 140 sanos, pareados por edad y sexo. Se utilizaron muestras aleatorias simples, con un tamaño poblacional de 110, una prevalencia de 50% y un nivel de confianza de 99%. Para establecer la diferencia entre las proporciones de los títulos se utilizó ji cuadrada y se calculó la razón de momios. Resultados. El 94.3% (66/70 de los pacientes presentó IgG en contra de C. pneumoniae vs 37% (52/140 de los individuos sanos (p<0.001. Conclusiones. Existe una fuerte asociación entre anticuerpos IgG hacia C. pneumoniae y ECV.

  4. Synthesis and structural property of Si nanosheets connected to Si nanowires using MnCl2/Si powder source

    Science.gov (United States)

    Meng, Erchao; Ueki, Akiko; Meng, Xiang; Suzuki, Hiroaki; Itahara, Hiroshi; Tatsuoka, Hirokazu

    2016-08-01

    Si nanosheets connected to Si nanowires were synthesized using a MnCl2/Si powder source with an Au catalyst. The synthesis method has benefits in terms of avoiding conventionally used air-sensitive SiH4 or SiCl4. The existence of the Si nanosheets connected to the Si nanowires, like sprouts or leaves with petioles, was observed, and the surface of the nanosheets was Si{111}. The nanosheets were grown in the growth direction of perpendicular to that of the Si nanowires. It was evident from these structural features of the nanosheets that the nanosheets were formed by the twin-plane reentrant-edge mechanism. The feature of the observed lattice fringes, which do not appear for Si bulk crystals, of the Si(111) nanosheets obtained by high resolution transmission electron microscopy was clearly explained due to the extra diffraction spots that arose by the reciprocal lattice streaking effect.

  5. Organic thin film transistors with a SiO2/SiNx/SiO2 composite insulator layer

    Institute of Scientific and Technical Information of China (English)

    Liu Xiang; Liu Hui

    2011-01-01

    We have investigated a SiO2/SiNx/SiO2 composite insulation layer structured gate dielectric for an organic thin film transistor (OTFT) with the purpose of improving the performance of the SiO2 gate insulator.The SiO2/SiNx/SiO2 composite insulation layer was prepared by magnetron sputtering.Compared with the same thickness of a SiO2 insulation layer device,the SiO2/SiNx/SiO2 composite insulation layer is an effective method of fabricating OTFT with improved electric characteristics and decreased leakage current.Electrical parameters such as carrier mobility by field effect measurement have been calculated.The performances of different insulating layer devices have been studied,and the results demonstrate that when the insulation layer thickness increases,the off-state current decreases.

  6. The production and growth of monocrystalline Si/CoSi2/Si heterostructures after high dose ion implantation

    International Nuclear Information System (INIS)

    CoSi2 is a favourable candidate for low ohmic interconnects in integrated circuits with high temperature stability. Its CaF2 structure is very similar to the diamond structure of Si with a lattice mismatch of only -1.2%. This allows epitaxial growth of Si/CoSi2/Si heterostructures required for three dimensional device applications. High dose Co+ implantation with subsequent annealing is a valuable method to form buried epitaxial CoSi2 layers with sharp interfaces both in (111)- and (100)-Si. The excellent crystalline quality of the surface Si layer enables the epitaxial growth of an additional Si layer to bury the silicide layer deeper into the substrate. Buried CoSi2 lines of several microns width were fabricated by implanting the Co+ ions through a thermally grown SiO2 mask patterned by photolithography. Both steps are necessary for the application of ion beam synthesis to microelectronics. (orig./BHO)

  7. AMPLEX-SiCAL

    International Nuclear Information System (INIS)

    This paper reports on an analog signal processor using commercial 3 μm CMOS technology which has been designed and produced for the silicon luminosity calorimeter SiCAL of the ALEPH experiment. This processor is a modified version of the AMPLEX integrated circuit designed for the inner silicon detector of the UA-2 experiment. The output voltage swing has been increased to more than 5.5 Volt as required for the large dynamic range of 1000 MIPs or 3.8 pC2. A fast analog summation, based on a neural network principle called follower aggregation, computes the average input charges for triggering purposes. The chip contains 16 channels, with a charge amplifier, shaper, track-and-hold stage, multiplexer, fast analog sum and a calibration system. The power consumption of the overall chip is 100 mW. The equivalent noise charge is less than 0.13MIP (0.5 fC rms) for a 50 pF detector capacitance, and the peaking time is about 250ns

  8. Si Isotopes of Brownleeite

    Science.gov (United States)

    Nakamura-Messenger, K.; Messenger, Scott R.; Ito, M.; Keller, L. P.; Clemett, S. J.; Jones, J. H.; Tatsuoka, H.; Zolensky, M. E.; Tatsuoka, H.

    2010-01-01

    Brownleeite is a manganese silicide, ideally stoichiometric MnSi, not previously observed in nature until its discovery within an interplanetary dust particle (IDP) that likely originated from a comet [1]. Three discrete brownleeite grains in the IDP L2055 I3 (4 microns in size, hereafter IDP I3) were identified with maximum dimensions of 100, 250 and 600 nm and fully analyzed using scanning-transmission electron microscopy (STEM) [1]. One of the grains (100 nm in size) was poikilitically enclosed by low-Fe, Mn-enriched (LIME) olivine. LIME olivine is epitaxial to the brownleeite with the brownleeite (200) parallel to the olivine c* [1]. LIME olivine is an enigmatic phase first reported from chondritic porous IDPs and some unequilibrated ordinary chondrites [ 2], that is commonly observed in chondritic-porous IDPs. Recently, LIME olivine has been also found in comet Wild-2 (Stardust) samples [3], indicating that LIME olivine is a common mineral component of comets. LIME olivine has been proposed to form as a high temperature condensate in the protosolar nebula [2]. Brownleeite grains also likely formed as high-temperature condensates either in the early Solar System or in the outflow of an evolved star or supernova explosion [1]. The isotopic composition of the brownleeite grains may strongly constrain their ultimate source. To test this hypothesis, we performed isotopic analyses of the brownleeite and the associated LIME olivine, using the NASA/JSC NanoSIMS 50L ion microprobe.

  9. Entre/vista a Langdon Winner

    Directory of Open Access Journals (Sweden)

    Andrés Lomeña

    2011-12-01

    Full Text Available La ballena y el reactor: Una búsqueda de los límites en la era de la alta tecnología se reeditó en 2008 con un prólogo de Javier Bustamante. Su autor, el politólogo Langdon Winner, ha sido uno de los pioneros en criticar la fascinación tecnológica de Occidente y en reflexionar sobre las consecuencias políticas, sociales y filosóficas de la tecnología. Su preocupación se ha centrado en cómo casi todos los aspectos de la vida humana han quedado sometidos a consideraciones de coste-beneficio. Esto le llevó a escribir un libro cuyo título nace de la epifanía que le hizo entender los problemas más acuciantes de las sociedades altamente tecnologizadas.Winner cuestionó tempranamente el dogma de la neutralidad tecnológica y expuso cómo los artefactos pueden tener intencionalidad política. Para ello usó varios y poderosos ejemplos: los pasos elevados de Long Island, denunciando los propósitos segregacionistas del planeamiento urbano en Nueva York, o la cosechadora mecánica de tomates, que alteró drásticamente la distribución del poder de la agricultura californiana.Si Lewis Mumford puede considerarse el antecesor directo de Winner, muchos otros autores han sido deudores indirectos de sus escritos. Los estudios de la ciencia (con la teoría del actor-red a la cabeza han heredado esa concepción de la tecnología como algo inherentemente político, no como un actor pasivo, frío e imparcial.

  10. Fabrication and characterization of CuxSi1-x films on Si (111) and Si (100) by pulsed laser deposition

    Science.gov (United States)

    Zhang, Song; Wu, Jun; He, Zhiqiang; Xie, Jun; Lu, Jingqi; Tu, Rong; Zhang, Lianmeng; Shi, Ji

    2016-05-01

    The CuxSi1-x thin films have been successfully fabricated by pulsed laser deposition (PLD). The influences of laser energy fluency (I0) and deposition temperature (Td) on the phase structure were investigated. The results show that Cu deposited on Si (001) at I0 = 0.5-2.0 J/cm2, and η"-Cu3Si formed on Si (111) at I0 = 1.0-2.0 J/cm2. The films were consisted of Cu, η'-Cu3Si, ɛ-Cu15Si4 and δ-Cu0.83Si0.17 at Td = 100-500 °C on Si (001). The films were the single phase of η-Cu3Si at Td = 700 °C. In the case of Si (111), the phase structures transformed from Cu to Cu + η'-Cu3Si to η'-Cu3Si to η'-Cu3Si + η-Cu3Si with the increasing of Td. Rectangular grains were formed on Si (001), whereas triangular grains on Si (111). Cu (001) film was epitaxially grown on Si (001) at I0 = 1.5 J/cm2 and Td = 20 °C. η-Cu3Si (001) epitaxial layer was formed on Si (111) at I0 = 1.5 J/cm2 and Td = 700 °C. The epitaxial relationships of Cu (001)[100]//Si (001)[110] and η-Cu3Si (001)[-110]//Si (111)[11-2] were identified.

  11. Nonlinear Modeling of Si/SiGe HBT Using ANN

    OpenAIRE

    Taher, H.; Schreurs, D; Vestiel, E.; Gillon, R; Nauwelaers, B.

    2004-01-01

    We present a large signal model for Si/SiGe HBTs using an Artificial Neural Network (ANN). The ANN is used to model the DC non-linearities of the intrinsic device. In this way, physical phenomena such as nonideal leakage currents and the Kirk effect can be modeled without time-consuming extraction. Capacitive nonlinearities are modeled by the well-known relationship between the capacitance and the junction voltage, ignoring the diffusion capacitance. By comparing ANN mode...

  12. Study of New Way about Si/Si Bonding

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A new set of technique was adopted in bonding Si-Si by using Ge (Ⅳ element),which is used as the substitute for the common hydrophilic method. The bond layer has no holes, and the edge bond-rate amounts to above 98%, and the bond strength is above 2156 Pa. By doping the same kind of dopant with low-resistance in Ge, the stress compensation was realized.

  13. Low-loss rib waveguides containing Si nanocrystals embedded in SiO2

    OpenAIRE

    Pellegrino, Paolo; Garrido Fernández, Blas; García Favrot, Cristina; Arbiol i Cobos, Jordi; Morante i Lleonart, Joan Ramon; Melchiorri, Mirko; Daldosso, Nicola; Pavesi, Lorenzo; Scheid, E; Sarrabayrouse, G.

    2005-01-01

    We report on the study and modeling of the structural and optical properties of rib-loaded waveguides working in the 600-900-nm spectral range. A Si nanocrystal (Si-nc) rich SiO2 layer with nominal Si excess ranging from 10% to 20% was produced by quadrupole ion implantation of Si into thermal SiO2 formed on a silicon substrate. Si-ncs were precipitated by annealing at 1100°C, forming a 0.4-um-thick core layer in the waveguide. The Si content, the Si-nc density and size, the Si-nc emission, a...

  14. The origin of blue photoluminescence from nc-Si/SiO2 multilayers

    Institute of Scientific and Technical Information of China (English)

    Ma Zhong-Yuan; Xu Ling; Huang Xin-Fan; Chen Kun-Ji; Feng Duan; Guo Si-Hua; Chen De-Yuan; Wei De-Yuan; Yao Yao; Zhou Jiang; Huang Rui; Li Wei; Xu Jun

    2008-01-01

    Intensive blue photoluminescence (PL) was observed at room temperature from the nanocrystalline-Si/SiO2 (ncSi/SiO2) multilayers (MLs) obtained by thermal annealing of SiO/SiO2 MLs for the first time.By controlling the size of nc-Si formed in SiO sublayer from 3.5 to 1.5 nm,the PL peak blueshifts from 457 to 411 nm.Combining the analysis of TEM,Raman and absorption measurement,this paper attributes the blue PL to multiple luminescent centres at the interface of nc-Si and SiO2.

  15. SiC/Si's CRYSTALLOGRAPHIC ORIENTATION RELATIONSHIP IN SiCp/Al-Si COMPOSITES%SiCp/Al-Si复合材料中SiC/Si的晶体学位向关系

    Institute of Scientific and Technical Information of China (English)

    隋贤栋; 罗承萍; 欧阳柳章; 骆灼旋

    2000-01-01

    用TEM研究了离心铸造和挤压铸造的SiCp/ZL109复合材料,发现Si优先在SiC表面上形核、长大,并形成大量"界面Si"及SiC/Si界面.SiC与Si之间不存在固定的晶体学位向关系,但存在(1101)sic//(111)si,[1120]sic∥[112]si优先出现的位向关系,而(0001)sic∥(111)si不是优先出现的位向关系.

  16. SiC表面处理对Si3N4-SiC材料显微结构的影响%Influence of SiC Surface Treatment on Microstructure of Si3N4-SiC

    Institute of Scientific and Technical Information of China (English)

    黎军

    2004-01-01

    在用反应烧结法制备Si3N4结合SiC复合材料时,如在反应前对SiC原料进行高温表面处理,可使SiC颗粒表面生成一层SiO2氧化层,该氧化层在高温、氮气气氛中会生成Si3N4颗粒或纤维,从而有效连接各SiC颗粒.

  17. Diversidad genética, entre y dentro de los mayores grupos humanos

    Directory of Open Access Journals (Sweden)

    Barbujani, G.

    2003-01-01

    Full Text Available Varios estudios están de acuerdo cuando reportan que cerca del 85% de la diversidad del ADN autosomal y de los loci de las proteínas se debe a diferencias entre individuos dentro de la misma población, mientras que las diferencias entre los grupos de diferentes continentes son responsables de solamente 10% de la variación genética total. Estos resultados están en conflicto con nociones populares de razas humanas claramente distintas y relativamente homogéneas, y nos hacen cuestionar la utilidad de clasificaciones étnicas en diagnósticos médicos, en el campo forense y en genética farmacológica. Nuevos datos obtenidos de inserciones polimórficas de Alu y del cromosoma Y confirman los resultados previos, aunque indican una diversidad mayor en algunos (pero no todos los loci del cromosoma Y. Estos datos nos permiten investigar dos preguntas: (1 si las diferencias continentales, aunque pequeñas, son suficientemente grandes como para asignar a individuos a sus continentes basados en sus genotipos; (2 si los genotipos observados se agrupan en grupos de población o continentales cuando el origen de la muestra se ignora. Usando varios métodos estadísticos, veremos que los errores de clasificación son por lo menos de un 30% para los polimorfismos autosomales bi-alélicos, y de un 27% para el cromosoma Y. Cuatro series de datos genéticos de todo el mundo sugieren la existencia de grupos de genotipos diferentes, pero que éstos cuatro grupos no coinciden el uno con el otro. Adicionalmente, estudios de bloques de ADN del genoma humano indican que la mayor parte de dichos bloques es compartida entre los continentes, con solamente un pequeño porcentaje siendo específico a ciertos continentes. Estos resultados no indican que haya una base clara para subdividir a los humanos en grupos biológicamente definidos. Este puede no ser un problema en áreas aplicadas de genéticas, dado que los métodos rápidos para obtener genotipos individuales

  18. Wallada Bint al Mustakfi entre dos culturas

    Directory of Open Access Journals (Sweden)

    shreen Mahmoud Al Refai

    2013-10-01

    Full Text Available La princesa cordobesa Wallada Bint al Mustakfi bil-lah, hija del califa al Mustakfi Muhammad Ibn Abdel Rahman Ibn Obaidil-lah Ibn Al Nasir lidin Al-lah era una poetisa estimable, a quien los grandes poetas no podían superar. Era una mujer única, guapa y decente. Mantenía una relación sentimental con el  poeta y visir Ibn Zaydún. Dicha pasión, narrada por los poemas escritos por ambos amantes, se terminó por la separación debida a los celos, también de ambos;  al poeta le gustó la voz de una esclava de la princesa. Eso dio rabia a la última. Movido también por los celos, Ibn Zaydún dedicó una epístola satírica al visir Ibn Abdús, que estaba enamorado de Wallada. Tal hecho también irritó a la princesa. A pesar de tener amantes y admiradores, Wallada murió sin casarse al  día 2 de safar de 480 (o 484 de la Híjira pasando los ochenta años Me han llamado la atención el carácter tan culto, independiente y liberal de aquella mujer, su relación amorosa con Ibn Zaydún que no acabó felizmente y los muchos años que vivió sin casasre. Parece que la vida de la princesa hispano-musulmana llamó también la atención de muchos escritores árabes y españoles. Prueba de ello son varias obras literarias escritas en árabe y en español sobre Wallada e Ibn Zaydún. Por consiguiente, me resulta muy interesante realizar un estudio comparativo sobre este tema averiguando si, o no, la diferencia de culturas influiría en las opiniones  de los autores sobre la vida sentimental de aquella poetisa cordobesa.

  19. Revealing heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys

    OpenAIRE

    Jiehua Li; Hage, Fredrik S.; Xiangfa Liu; Quentin Ramasse; Peter Schumacher

    2016-01-01

    The heterogeneous nucleation of primary Si and eutectic Si can be attributed to the presence of AlP. Although P, in the form of AlP particles, is usually observed in the centre of primary Si, there is still a lack of detailed investigations on the distribution of P within primary Si and eutectic Si in hypereutectic Al-Si alloys at the atomic scale. Here, we report an atomic-scale experimental investigation on the distribution of P in hypereutectic Al-Si alloys. P, in the form of AlP particles...

  20. THE STRUCTURE OF LIQUID LI-SI ALLOYS

    NARCIS (Netherlands)

    DEJONG, PHK; VERKERK, P; VANDERLUGT, W; DEGRAAF, LA

    1993-01-01

    The reverse Monte Carlo method is used to analyse neutron diffraction data on liquid Li65Si35. A well defined Si-Si partial pair correlation function is obtained with strong indications for covalent Si-Si bonds. It is also clear that most of the Si4 stars and Si5 rings occurring in solid Li12Si7 hav

  1. Ionic S(N)i-Si Nucleophilic Substitution in N-Methylaniline-Induced Si-Si Bond Cleavages of Si2Cl6.

    Science.gov (United States)

    Zhang, Jie; Xie, Ju; Lee, Myong Euy; Zhang, Lin; Zuo, Yujing; Feng, Shengyu

    2016-03-24

    N-Methylaniline-induced Si-Si bond cleavage of Si2Cl6 has been theoretically studied. All calculations were performed by using DFT at the MPWB1K/6-311++G(3df,2p)//MPWB1K/6-31+G(d,p) levels. An ionic SN i-Si nucleophilic substitution mechanism, which is a newly found nucleophilic substitution in silicon-containing compounds, is proposed in the N-methylaniline-induced Si-Si bond cleavage in Si2Cl6. Unlike general S(N)i-Si nucleophilic substitutions that go through a pentacoordinated silicon transition state, ionic nucleophilic substitution goes through a tetracoordinated silicon transition state, in which the Si-Si bond is broken and siliconium ions are formed. Special cleavage of the Si-Si bond is presumably due to the good bonding strength between Si and N atoms, which leads to polarization of the Si-Si bond and eventually to heterolytic cleavage. Calculation results show that, in excess N-methylaniline, the final products of the reaction, including (NMePh)(3-n) SiHCl(n) (n=0-2) and (NMePh)(4-n) SiCl(n) (n=2-3), are the Si-Si cleavage products of Si2Cl6 and the corresponding amination products of the former. The ionic S(N)i-Si nucleophilic substitution mechanism can also be employed to describe the amination of chlorosilane by N-methylaniline. The suggested mechanisms are consistent with experimental data.

  2. SiC-SiC and C-SiC Honeycomb for Advanced Flight Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed project builds upon the work done in Phase I with the development of a C-SiC CMC honeycomb material that was successfully tested for mechanical...

  3. Revealing heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys.

    Science.gov (United States)

    Li, Jiehua; Hage, Fredrik S; Liu, Xiangfa; Ramasse, Quentin; Schumacher, Peter

    2016-04-28

    The heterogeneous nucleation of primary Si and eutectic Si can be attributed to the presence of AlP. Although P, in the form of AlP particles, is usually observed in the centre of primary Si, there is still a lack of detailed investigations on the distribution of P within primary Si and eutectic Si in hypereutectic Al-Si alloys at the atomic scale. Here, we report an atomic-scale experimental investigation on the distribution of P in hypereutectic Al-Si alloys. P, in the form of AlP particles, was observed in the centre of primary Si. However, no significant amount of P was detected within primary Si, eutectic Si and the Al matrix. Instead, P was observed at the interface between the Al matrix and eutectic Si, strongly indicating that P, in the form of AlP particles (or AlP 'patch' dependent on the P concentration), may have nucleated on the surface of the Al matrix and thereby enhanced the heterogeneous nucleation of eutectic Si. The present investigation reveals some novel insights into heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys and can be used to further develop heterogeneous nucleation mechanisms based on adsorption.

  4. Revealing heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys

    Science.gov (United States)

    Li, Jiehua; Hage, Fredrik S.; Liu, Xiangfa; Ramasse, Quentin; Schumacher, Peter

    2016-04-01

    The heterogeneous nucleation of primary Si and eutectic Si can be attributed to the presence of AlP. Although P, in the form of AlP particles, is usually observed in the centre of primary Si, there is still a lack of detailed investigations on the distribution of P within primary Si and eutectic Si in hypereutectic Al-Si alloys at the atomic scale. Here, we report an atomic-scale experimental investigation on the distribution of P in hypereutectic Al-Si alloys. P, in the form of AlP particles, was observed in the centre of primary Si. However, no significant amount of P was detected within primary Si, eutectic Si and the Al matrix. Instead, P was observed at the interface between the Al matrix and eutectic Si, strongly indicating that P, in the form of AlP particles (or AlP ‘patch’ dependent on the P concentration), may have nucleated on the surface of the Al matrix and thereby enhanced the heterogeneous nucleation of eutectic Si. The present investigation reveals some novel insights into heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys and can be used to further develop heterogeneous nucleation mechanisms based on adsorption.

  5. Prospective crystallization of amorphous Si films for new Si TFTs

    Energy Technology Data Exchange (ETDEWEB)

    Noguchi, Takashi [University of the Ryukyus, Fuculty of Engineering, Nishihara, Okinawa (Japan)

    2008-07-01

    Prospective crystallization results of amorphous silicon film are reviewed and are discussed. Silicon TFTs are playing an important role for Active-Matrix Flat Panel Displays (AM-FPD) based on amorphous or poly-Si thin-film transistors (TFTs). Poly-Si TFTs provide a possibility to develop highly functional system on pane (SoP) applications. In order to get a high performance TFT, large poly-crystal grains or high cystallinity for the film is required. Two basic crystallization techniques namely solid phase crystallization (SPC) and excimer laser crystallization (ELC) are reviewed and relating issues are described. A grain growth technique has been developed based on the two crystallization techniques, so far. In order to mount a poly-Si TFT system on a flexible panel such as a plastic, an excimer laser of UV pulse beam has an advantage for the TFT channel as well as for the source and drain contacts as a ultra-low temperature poly-Si (U-LTPS) process. To realize a high performance TFT of uniform and high carrier mobility, location control crystallization had been proposed. Some of the distinctive results for crystal orientation control of (100) and (111) face using the laser crystallization techniques are described. In the future, single-crystalline Si TFT of a functional 3D structure is expected to realize an advanced SoP for ubiquitous electronics era. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Motivações do conceito de corpo-si: corpo-si, atividade, experiência = Motivations of the concept of selfbody: selfbody, activity, experience

    Directory of Open Access Journals (Sweden)

    Schwartz, Yves

    2014-01-01

    Full Text Available Este texto busca explicar a função de convergências e questões possibilitadoras do desenvolvimento da tese segundo a qual toda atividade de trabalho é sempre “uso de si, por si e por outros” (SCHWARTZ, 1987. Sucessivas reformulações levaram ao estabelecimento do seguinte princípio: toda atividade industriosa é sempre uma “dramática do uso de um corpo-si” (remetendo “dramática” à necessidade contínua de travar debates com normas. Sendo a atividade humana identificada assim como um contínuo debate de normas cujo lócus é o corpo-si, convém perguntar como, em termos de diferentes medidas temporais, esses debates se encaixam (à maneira das bonecas russas, ou seja, de que maneira as relações valorativas nos meios de vida e de trabalho se incorporam ao âmago do corpo-si, inclusive em termos de temporalidades mais curtas, “escondidas no corpo”. Cabe assim entender qual é a unidade enigmática dessa entidade – o corpo-si – que acumula experiência e saberes de formas extremamente diversas, notadamente em sua relação com a linguagem, que articula patrimônio epistêmico e sensibilidade axiológica, sem deixar de estar disponível para ou restrita por micro-escolhas e reajustamentos que a vida não cessa de lhe propor ou impor. O texto, retomando parcialmente, segundo seus objetivos, a distinção entre idem e ipse (RICOEUR, pretende conceber debates de normas encaixados como o cerne da dialética entre essas dimensões

  7. Synthesis and properties of Si and SiGe/Si nanowires

    Science.gov (United States)

    Redwing, Joan M.; Lew, Kok-Keong; Bogart, Timothy E.; Pan, Ling; Dickey, Elizabeth C.; Carim, A. H.; Wang, Yanfeng; Cabassi, Marco A.; Mayer, Theresa S.

    2004-06-01

    The fabrication of semiconductor nanowires, in which composition, size and conductivity can be controlled in both the radial and axial direction of the wire is of interest for fundamental studies of carrier confinement as well as nanoscale device development. In this study, group IV semiconductor nanowires, including Si, Ge and SixGe1-x alloy nanowires were fabricated by vapor-liquid-solid (VLS) growth using gaseous precursors. In the VLS process, gold is used to form a liquid alloy with Si and Ge which, upon supersaturation, precipitates a semiconductor nanowire. Nanoporous alumina membranes were used as templates for the VLS growth process, in order to control the diameter of the nanowires over the range from 45 nm to 200 nm. Intentional p-type and n-type doping was achieved through the addition of either trimethylboron, diborane or phosphine gas during nanowire growth. The electrical properties of undoped and intentionally doped silicon nanowires were characterized using field-assisted assembly to align and position the wires onto pre-patterned test bed structures. The depletion characteristics of back-gated nanowire structures were used to determine conductivity type and qualitatively compare dopant concentration. SiGe and SiGe/Si axial heterostructure nanowires were also prepared through the addition of germane gas during VLS growth. The Ge concentration in the wires was controllable over the range from 12 % to 25% by varying the inlet GeH4/SiH4 ratio.

  8. Relaciones entre calidad de vida, actividad física, sedentarismo y fitness cardiorrespiratorio en niños

    Directory of Open Access Journals (Sweden)

    Pere Palou

    2012-01-01

    Full Text Available El objetivo de este estudio fue explorar la relación entre algunos dominios de la calidad de vida, relacionada con la salud (CVRS en niños, con el estado cardiorrespiratorio, el nivel de actividad física, el sedentarismo (tiempo de pantalla y el índice de masa corporal de una población de 302 niños de once y doce años de edad, para determinar si la condición física (Fitness cardiorrespiratorio es un factor clave en lugar de la actividad física, para garantizar la futura calidad de vida de los niños. El cuestionario sobre salud infantil y calidad de vida (CHIP-CE / PRF- edición española se utilizó para medir la CVRS, El test de 20m de ida y vuelta para el fitness cardiorrespiratorio, El cuestionario de Salud Escolar de Acción, Planificación y Evaluación (SHAPES, módulo de actividad física, se utilizó para medir la actividad física semanal y el tiempo de pantalla. Los padres reportaron altura y peso. Los resultados muestran una fuerte correlación entre el fitness cardiovascular y la CVRS, y el tiempo de pantalla con la CVRS, pero no existe correlación entre CVRS y la actividad física.

  9. Construction and characterization of spherical Si solar cells combined with SiC electric power inverter

    Science.gov (United States)

    Oku, Takeo; Matsumoto, Taisuke; Hiramatsu, Kouichi; Yasuda, Masashi; Shimono, Akio; Takeda, Yoshikazu; Murozono, Mikio

    2015-02-01

    Spherical silicon (Si) photovoltaic solar cell systems combined with an electric power inverter using silicon carbide (SiC) field-effect transistor (FET) were constructed and characterized, which were compared with an ordinary Si-based converter. The SiC-FET devices were introduced in the direct current-alternating current (DC-AC) converter, which was connected with the solar panels. The spherical Si solar cells were used as the power sources, and the spherical Si panels are lighter and more flexible compared with the ordinary flat Si solar panels. Conversion efficiencies of the spherical Si solar cells were improved by using the SiC-FET.

  10. Si me das a elegir

    OpenAIRE

    Spiga, Claudio

    2012-01-01

    El debate por la despenalización de la marihuana ocupa a diez gobiernos americanos. Como en la versión cannábica de "La cucaracha", el presente canta una puesta al día entre las leyes y la realidad.

  11. Reactive diffusion bonding of SiCp/Al composites by insert layers of mixed Al-Si and Al-Si-SiC powders

    Institute of Scientific and Technical Information of China (English)

    Jihua Huang; Yueling Dong; Yun Wan; Jiangang Zhang; Hua Zhang

    2005-01-01

    Mixed Al-Si and Al-Si-SiC powders were employed as insert layers to reactive diffusion bond SiCp/6063 MMC (metal matrix composites). The results show that SiCp/6063 MMC joints bonded by the insert layer of the mixed Al-Si powder have a dense joining layer with a typical hypoeutectic microstructure. Using the mixed Al-Si-SiC powder as the insert layer, SiCp/6063 MMC can be reactive diffusion bonded by a composite joint. Because of the SiC segregation, however, there are a number of porous zones in the joining layer, which results in the bad shear strength of the joints reactive diffusion bonded by the insert layer of the mixed Al-SiSiC powder, even lower than that of the joints reactive diffusion bonded by the insert layer of the mixed Al-Si powder. Ti and Mg added in the insert layers obviously improve the strength of the joints reactive diffusion bonded by the insert layer of the mixed AlSi-SiC powder, especially, Mg has a more obvious effect.

  12. Les revues littéraires dans l’entre-deux-guerres entre France et Grèce. Réseaux, transferts culturels et traduction

    Directory of Open Access Journals (Sweden)

    Lucile Arnoux-Farnoux

    2015-12-01

    Full Text Available Pendant l’entre-deux-guerres, certaines revues littéraires grecques adoptent uneattitude hellénocentriste, tandis que d’autres s’ouvrent au contraire largement à l’étranger.Cette ouverture se manifeste bien sûr par la publication d’oeuvres en traduction, maisaussi par un intérêt grandissant pour les revues étrangères, et en particulier françaises,qui se marque par l’emprunt d’articles et surtout par la création de rubriques spécialisées.Le but de ce travail est de mettre en lumière l’existence de relations privilégiées entrerevues grecques et revues françaises comme vecteurs de transferts culturels –qu’il s’agissede la reprise de modèles éditoriaux ou de la circulation de textes, d’idées ou même decollaborateurs–, d’évaluer la part que la traduction prend dans l’établissement de cesrelations et enfin de déterminer si on peut ou non parler dans ces cas de “réseau derevues”, comme cela a été fait dans d’autres contextes européens.

  13. Room-temperature formation of Pt$_3$Si/Pt$_2$Si films on poly-Si substrates

    CERN Document Server

    Dubkov, V P; Chizh, K V; Yuryev, V A

    2016-01-01

    We propose a way of formation of thin bilayer Pt$_3$Si/Pt$_2$Si films at room temperature on poly-Si substrates by Pt magnetron sputtering and wet etching, obtain such film, investigate its structure and phase composition and estimate the thickness of its layers. We verify by direct x-ray photoelectron-spectroscopic measurements our previous observation of the Pt$_2$Si layer formaton between Pt and poly-Si films as a result of Pt magnetron sputtering at room temperature. This layer likely appears due to high enough temperature of Pt ions in the magnetron plasma sufficient for chemical reaction of the silicide film formation on the Si surface. The Pt$_3$Si layer likely forms from the Pt--Pt$_3$Si layer (Pt$_{95}$Si$_5$), which arises under Pt film during the magnetron sputtering, as a result of Pt removal by wet etching.

  14. ENTRE DOS INTEMPERIES. APUNTES SOBRE LAS RELACIONES ENTRE EL FORO Y EL MERCADO

    Directory of Open Access Journals (Sweden)

    Antonio Armesto Aira

    2010-05-01

    Full Text Available RESUMEN Este ensayo encadena tres niveles. En el primero, de la pregunta por la utilidad genuina de la arquitectura, definida en los orígenes, se deriva que la arquitectura preserva la vida de dos clases de intemperie: de la intemperie física, procurando un equilibrio con el medio (homeostasis y de la intemperie moral procurando orientación espacio temporal. Esta doble utilidad la cumplen y la expresan unos utensilios concretos y universales, formas necesarias y objetivas, no arbitrarias, arquetipos que fundan la tradición de las formas propias de la arquitectura en la historia. El êthos de la humanidad, cuyo núcleo es la conciencia, para constituirse tomará de la formalidad de estos utensilios su propia sustancia formal, desde el momento en que con ellos es capaz de conjurar el tiempo destructor de la vida (meteorológico y cronológico – un tiempo discontinuo–, y exorcizar el espacio amorfo –un espacio continuo– y desorientador de la naturaleza. Esos utensilios forman un relieve tectónico, superpuesto al de la naturaleza otorgada, al que llamamos paisaje.En el segundo nivel se descubre que la estructura de ese paisaje reposa sobre la similitud entre estas formas objetivas y los caracteres del mercado y del foro que se corresponden, respectivamente, con la idea de homeostasis y con la de orientación.En el tercer nivel se estudian las modalidades de relación entre foro y mercado con el objeto de hallar instrumentos para hacer la crítica del presente. El criterio principal es que foro y mercado deben mantener en la realidad una relación dialógica (conservar su contradicción o composición y no dialéctica pues una síntesis superadora entre ellos, cuando se da, conlleva un decaimiento de la formalidad de la conciencia, menoscaba el êthos de la humanidad y produce la quiebra ética del paisaje.SUMMARYThis essay encompasses three levels. The first, on the question of the genuine utility of architecture, defined in the origins

  15. Recent Progress of SiC-Fibers and SiC/SiC-Composites for Fusion Applications

    Science.gov (United States)

    Noda, T.; Kohyama, A.; Katoh, Y.

    Recent progress in R&D of SiC fibers and reinforced SiC matrix (SiC/SiC) composites in Japan, especially focusing on the activities of CREST-ACE program, is presented. Firstly, the present status of high performance SiC fiber development, such as Hi-Nicalon Type-S and Tyrano-SA, is provided. The high performance SiC matrix production by reaction sintering (RS) method improved in both strength and thermal conductivity are accomplished. The efforts to make appropriate fiber-matrix interfacial microstructure by CVI and PIP methods have been successful, resulting in the production of high strength and high fracture toughness SiC/SiC composites. Several joining processes using PIP, RS and mechanical fastener for composites are introduced. Dimensional stability under radiation damage has been studied by neutron and charged particle irradiation. The SiC/SiC composites prepared with Type-S SiC fiber with a stoichiometric composition did not exhibit mechanical property degradation. Based on the development of SiC composites, test module concepts to verify the advanced fluid systems including SiC/SiC/Be/He coolant blanket are presented.

  16. MATAR, MORRER E CRER EM BOTOPÁSI, ALTO SURINAME

    Directory of Open Access Journals (Sweden)

    Rogério Brittes Pires

    2014-10-01

    Full Text Available Uma reflexão sobre a interação entre o cristianismo e outras práticas e saberes mágico-religiosos afro-americanos, na aldeia maroon saamaka Botopási, no Alto Suriname. Ao buscar entender como a filosofia moral saamaka lida com graves crimes como o assassinato, é aberta uma discussão sobre a agência sobrenatural do Deus criador, dos espíritos vingativos conhecidos como kúnu, das receitas mágicas chamadas óbia e de outras entidades e divindades. A importância da noção de crença, aparece com vigor neste pensamento, bem como uma visão particular da temporalidade e da intencionalidade das ações humanas e não-humanas.

  17. MATAR, MORRER E CRER EM BOTOPÁSI, ALTO SURINAME

    OpenAIRE

    Rogério Brittes Pires

    2014-01-01

    Uma reflexão sobre a interação entre o cristianismo e outras práticas e saberes mágico-religiosos afro-americanos, na aldeia maroon saamaka Botopási, no Alto Suriname. Ao buscar entender como a filosofia moral saamaka lida com graves crimes como o assassinato, é aberta uma discussão sobre a agência sobrenatural do Deus criador, dos espíritos vingativos conhecidos como kúnu, das receitas mágicas chamadas óbia e de outras entidades e divindades. A importância da noção de crença, aparece com vig...

  18. Mo-Si alloy development

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Heatherly, L.; Wright, J.L. [Oak Ridge National Lab., TN (United States)

    1996-06-01

    The objective of this task is to develop new-generation corrosion-resistant Mo-Si intermetallic alloys as hot components in advanced fossil energy conversion and combustion systems. The initial effort is devoted to Mo{sub 5}-Si{sub 3}-base (MSB) alloys containing boron additions. Three MSB alloys based on Mo-10.5Si-1.1B (wt %), weighing 1500 g were prepared by hot pressing of elemental and alloy powders at temperatures to 1600{degrees}C in vacuum. Microporosities and glassy-phase (probably silicate phases) formations are identified as the major concerns for preparation of MSB alloys by powder metallurgy. Suggestions are made to alleviate the problems of material processing.

  19. Irradiation effects on thermal expansion of SiC/SiC composite materials

    International Nuclear Information System (INIS)

    Irradiation-induced dimensional change and thermal expansion of two kinds of composites, self-particle reinforced SiCp/SiC composites and a Hi-Nicalon SiC fiber reinforced SiCf/SiC composite, and monolithic α-SiC were measured after irradiation at 0.2 dpa with irradiation temperatures of 573, 673 and 843 K using the JMTR. From the measurement, swelling was observed for the SiCp/SiC composites and the monolithic α-SiC, on the contrary, the SiCf/SiC composites showed a shrinkage. The measured thermal expansion increased with increasing the specimen temperature below the irradiation temperature, and then rapidly decreased over the irradiation temperature. The so-called 'temperature monitor effect' of the silicon carbide was clearly observed for all specimens, the monolithic α-SiC and both composites

  20. HV/CVD Grown Relaxed SiGe Buffer Layers for SiGe HMOSFETs

    Institute of Scientific and Technical Information of China (English)

    黄文韬; 罗广礼; 史进; 邓宁; 陈培毅; 钱佩信

    2003-01-01

    High-vacuum/chemical-vapor deposition (HV/CVD) system was used to grow relaxed SiGe buffer layers on Si substrates. Several methods were then used to analyze the quality of the SiGe films. X-ray diffraction and Raman spectroscopy showed that the upper layer was almost fully relaxed. Second ion mass spectroscopy showed that the Ge compositions were step-graded. Transmission electron microscopy showed that the misfit dislocations were restrained to the graded SiGe layers. Tests of the electrical properties of tensile-strained Si on relaxed SiGe buffer layers showed that their transconductances were higher than that of Si devices. These results verify the high quality of the relaxed SiGe buffer layer. The calculated critical layer thicknesses of the graded Si1-xGex layer on Si substrate and a Si layer on the relaxed SiGe buffer layer agree well with experimental results.

  1. High thermal conductivity SiC/SiC composites for fusion applications -- 2

    Energy Technology Data Exchange (ETDEWEB)

    Kowbel, W.; Tsou, K.T.; Withers, J.C. [MER Corp., Tucson, AZ (United States); Youngblood, G.E. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-03-01

    This report covers material presented at the IEA/Jupiter Joint International Workshop on SiC/SiC Composites for Fusion Structural Applications held in conjunction with ICFRM-8, Sendai, Japan, Oct. 23--24, 1997. An unirradiated SiC/SiC composite made with MER-developed CVR SiC fiber and a hybrid PIP/CVI SiC matrix exhibited room temperature transverse thermal conductivity of 45 W/mK. An unirradiated SiC/SiC composite made from C/C composite totally CVR-converted to a SiC/SiC composite exhibited transverse thermal conductivity values of 75 and 35 W/mK at 25 and 1000 C, respectively. Both types of SiC/SiC composites exhibited non-brittle failure in flexure testing.

  2. On the structure and chemical bonding of Si62- and Si62- in NaSi6- upon Na+ coordination

    Science.gov (United States)

    Zubarev, Dmitry Yu.; Alexandrova, Anastassia N.; Boldyrev, Alexander I.; Cui, Li-Feng; Li, Xi; Wang, Lai-Sheng

    2006-03-01

    Photoelectron spectroscopy was combined with ab initio calculations to elucidate the structure and bonding in Si62- and NaSi6-. Well-resolved electronic transitions were observed in the photoelectron spectra of Si6- and NaSi6- at three photon energies (355, 266, and 193nm). The spectra of NaSi6- were observed to be similar to those of Si6- except that the electron binding energies of the former are lower, suggesting that the Si6 motif in NaSi6- is structurally and electronically similar to that in Si6-. The electron affinities of Si6 and NaSi6 were measured fairly accurately to be 2.23±0.03eV and 1.80±0.05eV, respectively. Global minimum structure searches for Si62- and NaSi6- were performed using gradient embedded genetic algorithm followed by B3LYP, MP2, and CCSD(T) calculations. Vertical electron detachment energies were calculated for the lowest Si6- and NaSi6- structures at the CCSD(T)/6-311+G(2df ), ROVGF/6-311+G(2df), UOVGF/6-311+G(2d), and time-dependent B3LYP/6-311+G(2df) levels of theory. Experimental vertical detachment energies were used to verify the global minimum structure for NaSi6-. Though the octahedral Si62-, analogous to the closo form of borane B6H62-, is the most stable form for the bare hexasilicon dianion, it is not the kernel for the NaSi6- global minimum. The most stable isomer of NaSi6- is based on a Si62- motif, which is distorted into C2v symmetry similar to the ground state structure of Si6-. The octahedral Si62- coordinated by a Na+ is a low-lying isomer and was also observed experimentally. The chemical bonding in Si62- and NaSi6- was understood using natural bond orbital, molecular orbital, and electron localization function analyses.

  3. Progress of Si-based Optoelectronic Devices

    Institute of Scientific and Technical Information of China (English)

    PENG Ying-cai; FU Guang-sheng; WANG Ying-long; SHANG Yong

    2004-01-01

    Si-based optoelectronics is becoming a very active research area due to its potential applications to optical communications. One of the major goals of this study is to realize ali-Si optoelectronic integrated circuit. This is due to the fact that Si- based optoelectronic technology can be compatible with Si microelectronic technology. If Si-based optoelectronic devices and integrated circuits can be achieved,it will lead to a new informational technological revolution. In the article, the current developments of this exciting field are mainly reviewed in the recent years. The involved contents are the realization of various Si-based optoelectronic devices, such as light-emitting diodes,optical waveguides devices, Si photonic bandgap crystals,and Si laser,etc. Finally, the developed tendency of all-Si optoelectronic integrated technology are predicted in the near future.

  4. Laser annealing of sputter-deposited -SiC and -SiCN films

    Indian Academy of Sciences (India)

    M A Fraga; M Massi; I C Oliveira; F D Origo; W Miyakawa

    2011-12-01

    This work describes the laser annealing of -SiC and -SiCN films deposited on (100) Si and quartz substrates by RF magnetron sputtering. Two samples of -SiCN thin films were produced under different N2/Ar flow ratios. Rutherford backscattering spectroscopy (RBS), Raman analysis and Fourier transform infrared spectrometry (FTIR) techniques were used to investigate the composition and bonding structure of as-deposited and laser annealed SiC and SiCN films.

  5. Analysis of Si/SiGe Heterostructure Solar Cell

    Directory of Open Access Journals (Sweden)

    Ashish Kumar Singh

    2014-01-01

    Full Text Available Sunlight is the largest source of carbon-neutral energy. Large amount of energy, about 4.3 × 1020 J/hr (Lewis, 2005, is radiated because of nuclear fusion reaction by sun, but it is unfortunate that it is not exploited to its maximum level. Various photovoltaic researches are ongoing to find low cost, and highly efficient solar cell to fulfil looming energy crisis around the globe. Thin film solar cell along with enhanced absorption property will be the best, so combination of SiGe alloy is considered. The paper presented here consists of a numerical model of Si/Si1-xGex heterostructure solar cell. The research has investigated characteristics such as short circuit current density (Jsc, generation rate (G, absorption coefficient (α, and open circuit voltage (Voc with optimal Ge concentration. The addition of Ge content to Si layer will affect the property of material and can be calculated with the use of Vegard’s law. Due to this, short circuit current density increases.

  6. Investigation of an a-Si/c-Si interface on a c-Si(P) substrate by simulation

    Institute of Scientific and Technical Information of China (English)

    Wang Jianqiang; Gao Hua; Zhang Jian; Meng Fanying; Ye Qinghao

    2012-01-01

    We investigate the recombination mechanism in an a-Si/c-Si interface,and analyze the key factors that influence the interface passivation quality,such as Qs,δp/δn and Dit.The polarity of the dielectric film is very important to the illustration level dependent passivation quality; when nδn =pδp and the defect level Et equal to Ei (c-Si),the defect states are the most effective recombination center,AFORS-HET simulation and analysis indicate that emitter doping and a-Si/c-Si band offset modulation are effective in depleting or accumulating one charged carrier.Interface states (Dit) severely deteriorate Voc compared with Jsc for a-Si/c-Si HJ cell performance when Dit is over 1 × 1010 cm-2.eV-1.For a c-Si(P)/a-Si(P+) structure,ΦBSF in c-Si and Φo in a-Si have different performances in optimization contact resistance and c-Si(P)/a-Si(P+) interface recombination.

  7. Convergencia de normas contables internacionales entre México y Estados Unidos: evidencia empírica

    Directory of Open Access Journals (Sweden)

    Sergio Demetrio Polo Jiménez

    2015-12-01

    Full Text Available El objetivo de este trabajo es examinar si la adaptación de la normativa contable mexicana a las IFRS ha convertido los principios mexicanos en unas normas de mayor calidad, incrementando su comparabilidad con los US GAAP y reduciendo la manipulación de los resultados. A su vez, nos cuestionamos, de acuerdo con la Teoría de la Agencia, si las diferencias entre las variables contables calculadas bajo la normativa mexicana y americana pueden ser debidas a la interpretación oportunista de los estándares mexicanos por los managers más que a las diferencias en la normativa contable de ambos países. Los resultados sugieren que los esfuerzos para converger las normas contables han incrementado la comparabilidad del resultado contable, si bien esta convergencia se debe también al uso oportunista de la elección de los métodos contables en función de la distinta coyuntura económica.

  8. Structures and relative stability of medium- and large-sized silicon clusters. VI. Fullerene cage motifs for low-lying clusters Si39, Si40, Si50, Si60, Si70, and Si80

    Science.gov (United States)

    Yoo, Soohaeng; Shao, N.; Zeng, X. C.

    2008-03-01

    We performed a constrained search, combined with density-functional theory optimization, of low-energy geometric structures of silicon clusters Si39, Si40, Si50, Si60, Si70, and Si80. We used fullerene cages as structural motifs to construct initial configurations of endohedral fullerene structures. For Si39, we examined six endohedral fullerene structures using all six homolog C34 fullerene isomers as cage motifs. We found that the Si39 constructed based on the C34(Cs:2) cage motif results in a new leading candidate for the lowest-energy structure whose energy is appreciably lower than that of the previously reported leading candidate obtained based on unbiased searches (combined with tight-binding optimization). The C34(Cs:2) cage motif also leads to a new candidate for the lowest-energy structure of Si40 whose energy is notably lower than that of the previously reported leading candidate with outer cage homolog to the C34(C1:1). Low-lying structures of larger silicon clusters Si50 and Si60 are also obtained on the basis of preconstructed endohedral fullerene structures. For Si50, Si60, and Si80, the obtained low-energy structures are all notably lower in energy than the lowest-energy silicon structures obtained based on an unbiased search with the empirical Stillinger-Weber potential of silicon. Additionally, we found that the binding energy per atom (or cohesive energy) increases typically >10meV with addition of every ten Si atoms. This result may be used as an empirical criterion (or the minimal requirement) to identify low-lying silicon clusters with size larger than Si50.

  9. SOBRE LA TENSIÓN ENTRE ONTOLOGÍA E HISTORIA: EL SER DE LO POLÍTICO COMO DIFERENCIA

    Directory of Open Access Journals (Sweden)

    Nuria Yabkowski

    2010-12-01

    Full Text Available Resumen Proponer una ontología de lo político implica preguntarse por la relación que se establece entre ontología e historia. Si ambos términos se presentan como opuestos y excluyentes entre sí, entonces tendríamos que aceptar la posibilidad de que lo político pueda concebirse con plena autonomía de un contexto histórico determinado. Aquí, por el contrario, se trata de pensar una ontología de lo político que mantenga con la historia una relación distinta o, en otras palabras, una ontología política materialista. Para abordar esta problemática partimos de la obra de Nicos Poulantzas, para dar cuenta con ella de las dificultades que enfrentaba un marxismo en crisis a la hora de pensar la autonomía de la política. El posmarxismo enfrenta estos dilemas y elabora algunas respuestas sobre la relación entre ontología e historia. Para exponer lo que muchos de estos desarrollos comparten, recurrimos a la interpretación de Oliver Marchart sobre lo que él denomina el pensamiento político posfundacional (Cf. Lefort, Badiou, Laclau, Rancière. Luego recurrimos a los postulados de Gilles Deleuze, porque con ellos podemos desplazar de otra forma la tradicional antinomia entre ontología e historia. Entonces, asumiendo que el Ser de lo político es un ser que siempre se dice de la diferencia, nos abocamos a analizar críticamente las teorizaciones de Ernesto Laclau sobre la política y su forma hegemónica. Finalmente, la relación que propone Benjamín Arditi entre espectro y populismo permite pensar nuevas relaciones entre la ontología y la historia, lo político y la diferencia, dinamizando los conceptos.

  10. Redundância entre métricas da qualidade ambiental de riachos em paisagem agrícola

    Directory of Open Access Journals (Sweden)

    Marcel Okamoto Tanaka

    2015-11-01

    Full Text Available Indicadores ambientais são amplamente usados para avaliação da qualidade dos corpos d’água. Como o monitoramento envolve alto custo de amostragem, e a construção de índices multimétricos pressupõe métricas não correlacionadas, este estudo avaliou se havia correlação entre métricas que caracterizam o uso e cobertura do solo, composição da zona ripária e estrutura da floresta, bem como correlações entre indicadores das comunidades de macroinvertebrados e peixes. O estudo foi feito em 12 afluentes de baixa ordem dos rios Jacaré-Pepira e Jacaré-Guaçu, formando um gradiente de estresse ambiental no estado de São Paulo. Não houve correlação entre as métricas relacionadas ao uso e cobertura do solo, e apenas a proporção de pastos foi negativamente correlacionada com algumas métricas da estrutura da floresta ripária. Assim, tanto as informações do uso e cobertura do solo quanto sobre a composição da zona ripária e estrutura das florestas podem ser importantes na avaliação ambiental de riachos. As métricas relacionadas às comunidades de macroinvertebrados foram correlacionadas entre si, assim como a maioria das métricas relacionadas às comunidades de peixes. Estudos propondo índices multimétricos não encontraram correlação entre estas variáveis, mas avaliaram riachos em situações extremas (preservados vs. impactados, sendo os riachos impactados influenciados por diferentes condutores de degradação, o que pode resultar em respostas distintas das comunidades biológicas. Os resultados deste estudo sugerem que o desenvolvimento de índices deve ser bastante específico para cada região estudada, e que muitas vezes as avaliações são feitas em relação a condutores de impactos específicos, que podem variar entre diferentes sistemas.

  11. Relação entre estressores, estresse e ansiedade

    Directory of Open Access Journals (Sweden)

    Margis Regina

    2003-01-01

    Full Text Available Os autores apresentam uma breve revisão de literatura sobre a relação entre ansiedade, eventos estressores e estresse. São descritas as diferentes situações estressoras, a definição de evento de vida estressor e os aspectos cognitivos, comportamentais e fisiológicos da resposta frente ao estresse. A neuroanatomia e os principais neurotransmissores envolvidos na resposta fisiológica de ansiedade ao estresse são descritos. Estudos genéticos que evidenciam a relação entre os eventos de vida estressores como fator de risco para ansiedade são apresentados. A relação causal entre os eventos de vida estressores e o aparecimento de ansiedade é abordada a partir de estudos realizados com adultos e adolescentes.

  12. Mejora de la comunicación entre Atención Primaria y Atención Especializada con una Historia Clínica Electrónica compartida.

    OpenAIRE

    Elviro Bodoy, Tirso; Escolar Castellón, Fernando; Martínez-Berganza Asensio, Alberto Jerónimo Santiago

    2009-01-01

    El trabajo describe un sistema de comunicación informatizada, entre los médicos de atención primaria del Centro de Salud y un centro de especialistas ubicados en el mismo centro de salud utilizando la misma historia clínica informatizada. Esta historia clínica electrónica compartida mejora la comunicación entre Atención Primaria y Especializada si las derivaciones se hacían a través del mismo sistema de información. -Los porcentajes de los niveles de cumplimentación tanto de envío de informa...

  13. Microwave joining of SiC

    Energy Technology Data Exchange (ETDEWEB)

    Silberglitt, R.; Ahmad, I.; Tian, Y.L. [FM Technologies, Inc., Fairfax, VA (United States)] [and others

    1997-04-01

    The purpose of this work is to optimize the properties of SiC-SiC joints made using microwave energy. The current focus is on identification of the most effective joining methods for scale-up to large tube assemblies, including joining using SiC produced in situ from chemical precursors. During FY 1996, a new microwave applicator was designed, fabricated and tested that provides the capability for vacuum baking of the specimens and insulation and for processing under inert environment. This applicator was used to join continuous fiber-reinforced (CFCC) SiC/SiC composites using a polymer precursor to form a SiC interlayer in situ.

  14. Interface engineering of photoelectrochemically prepared Si surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lewerenz, H.J.; Murrell, C.; Kanis, M.; Jungblut, H. [Department of Interfaces, Bereich Solarenergie, Hahn-Meitner-Institut Berlin, Glienicker Str. 100, D-14109 Berlin (Germany); Aggour, M. [University of Tofail, Kenitra (Morocco); Hoffmann, P.; Schmeisser, D. [Fakultaet 1, Brandenburgisch-Technische Universitaet, Cottbus (Germany)

    2002-05-01

    The oxide of Si(111) formed by electropolishing in dilute ammonium fluoride solution is analysed by photoelectron spectroscopy using synchrotron radiation. The oxidic layer is about 3.1 nm thick and contains Si-F{sub x} species as well as oxyfluorides. The oxyfluorides are found preferentially at the electropolishing layer surface. SiOH species are concentrated at the oxidic film/substrate interface. The full width half maximum of the Si 2p line indicates that the Si/electropolishing oxide interface is smoother than the Si/natural oxide interface.

  15. Straight β-SiC nanorods synthesized by using C-Si-SiO2

    Science.gov (United States)

    Lai, H. L.; Wong, N. B.; Zhou, X. T.; Peng, H. Y.; Au, Frederick C. K.; Wang, N.; Bello, I.; Lee, C. S.; Lee, S. T.; Duan, X. F.

    2000-01-01

    Straight beta-silicon carbide nanorods have been grown on silicon wafers using hot filament chemical vapor deposition with iron particles as catalyst. A plate made of a C-Si-SiO2 powder mixture was used as carbon and silicon sources. Hydrogen, which was the only gas fed into the deposition system, acts both as a reactant and as a mass transporting medium. The diameter of the β-SiC nanorod ranged from 20 to 70 nm, while its length was approximately 1 μm. A growth mechanism of beta-silicon carbide nanorods was proposed. The field emission properties of the beta-silicon carbide nanorods grown on the silicon substrate are also reported.

  16. Microscopic and macroscopic characterization of the charging effects in SiC/Si nanocrystals/SiC sandwiched structures

    International Nuclear Information System (INIS)

    Microscopic charge injection into the SiC/Si nanocrystals/SiC sandwiched structures through a biased conductive AFM tip is subsequently characterized by both electrostatic force microscopy and Kelvin probe force microscopy (KPFM). The charge injection and retention characteristics are found to be affected by not only the band offset at the Si nanocrystals/SiC interface but also the doping type of the Si substrate. On the other hand, capacitance–voltage (C–V) measurements investigate the macroscopic charging effect of the sandwiched structures with a thicker SiC capping layer, where the charges are injected from the Si substrates. The calculated macroscopic charging density is 3–4 times that of the microscopic one, and the possible reason is the underestimation of the microscopic charging density caused by the averaging effect and detection delay in the KPFM measurements. (paper)

  17. Entre miasmas y microbios: la vivienda popular higienizada

    Directory of Open Access Journals (Sweden)

    Sandra Caponi

    2002-12-01

    Full Text Available Analizando la influencia del primer pasteurianismo en los discursos y las prácticas sanitarias, en este trabajo discuto la tesis que postula una oposición entre la higiene pre y post pasteuriana. Centrando mi análisis en las estrategias sanitarias encaminadas a controlar la vivienda popular que fueron propuestas por higienistas de Brasil y Argentina, muestro las rupturas y las continuidades entre la higiene clásica y aquélla que se reorganizó a partir de la microbiología.

  18. Arquitectura de comunicación entre frameworks jadesymfony

    OpenAIRE

    RODRÍGUEZ C., PAOLA J.; GÓMEZ R., SANTIAGO

    2009-01-01

    La inclusión del uso de Agentes dentro del campo del desarrollo de software es una de las principales áreas de estudio en la actualidad. Específicamente, el desarrollo de aplicaciones Web que aprovechen las ventajas que ofrece la tecnología de agentes y en especial las distintas propuestas de comunicación entre frameworks son esfuerzos importantes dentro de este campo. En este sentido, este artículo describe una arquitectura de comunicación entre dos de los principales frameworks de desarroll...

  19. ¿Relaciones entre metafísica y arte?

    OpenAIRE

    Vélez León, Paulo

    2013-01-01

    [ES] En el presente trabajo nos proponemos hacer visible una posible relación entre metafísica y arte, a partir del presupuesto de que, en cuanto absolutos son lo mismo; es así que, aquello que digamos de la metafísica es válido para el arte. Sin embargo, la distinción entre metafísica y arte no es factible de evidenciar en el mundo, en especial en un acontecimiento artístico, como por ejemplo una muestra o concierto, sino por las distinciones del mundo. Esta cuestión intentaremos abordarla d...

  20. Personalidad Resistente en Carreras de Fondo: comparativa entre ultra fondo y diez kilómetros

    Directory of Open Access Journals (Sweden)

    Ricardo de la Vega

    2011-01-01

    Full Text Available La Personalidad Resistente es una característica individual que permite hacer frente a los estímulos estresores de la vida y convertirlos en oportunidades de crecimiento (Kobasa, 1979; Maddi, 2006. Sus tres componentes: Compromiso, Control y Desafío pueden proteger a los deportistas contra las impredecibles situaciones de las carreras de fondo. El objetivo de este estudio fue comparar por primera vez los niveles de personalidad resistente de dos grupos de corredores de fondo, así como determinar si existe una relación entre los niveles de personalidad resistente y el rendimiento deportivo. 130 voluntarios (69 corredores de ultrafondo y 61 corredores participantes de una prueba de 10.06 kilómetros con un rango de edad de 20 a 56 años (M = 35.4, DT = 7.3, quienes completaron el día de la competición la Escala de Personalidad Resistente en Maratonianos (EPRM (Jaenes, Godoy y Román, 2008. El análisis de comparación de medias, reveló que no existieron diferencias significativas entre ambos grupos de corredores de fondo (Z = .280, p = .77, así mismo las mejores marcas en la prueba de ultra fondo fueron independientes de los niveles de personalidad resistente (r = -.072, p = .30, aquellos corredores que completaron el recorrido de ultrafondo no presentaron niveles mayores de personalidad resistente que los deportistas que abandonaron (p =. 78. Los resultados sugieren que un nivel elevado de personalidad resistente forma parte de las características psicológicas de los corredores de fondo. Por otra parte un nivel elevado de personalidad resistente no tuvo influencia sobre el rendimiento obtenido en una carrera de ultrafondo.

  1. LA EVOLUCIÓN DE LA RSC EN BRASIL ENTRE LAS EMPRES AS COTIZADAS EN BOVESPA

    Directory of Open Access Journals (Sweden)

    Ana Gisbert

    2012-03-01

    Full Text Available El objetivo de este trabajo es analizar los avances en responsabilidad social en Brasil, haciendo énfasis en el tipo de información presentada y el nivel de las inversiones realizadas durante el período 2003-2007. El análisis empírico está basado en el contenido de los informes de RSC publicados por las empresas cotizadas en Bovespa, entre las que se encuentran las compañías que componen la cartera del Índice de Sostenibilidad Empresarial y Responsabilidad Social Corporativa de la bolsa de valores de Sao Paulo (Bovespa. La muestra analizada está compuesta por 48 compañías cotizadas. En el análisis empírico se ha analizado el contenido de los informes anuales de las empresas de la muestra entre los años 2003 a 2007. Todos los proyectos en RSC desarrollados por las compañías de la muestra han sido clasificados en 11 categorías, así como em tres grandes grupos de inversión: externa, interna y medioambiental. Los resultados ponen de manifiesto la necesidad de potenciar la estandarización del formato de presentación de los informes de responsabilidade social corporativa debido a la ausencia de uniformidad. Asimismo, se observa que las empresas invierten em proyectos que en la mayor parte de los casos están muy relacionados con la actividad principal que desarrollan. Respecto al crecimiento de la inversión, el mayor avance durante el periodo temporal analizado se encuentra en la inversión externa, si bien la inversión en proyectos internos ha aumentado de forma considerable. La inversión medioambiental es la que se ha mantenido, debido especialmente a una significativa reducción en el sector petrolífero.

  2. Risco nutricional entre gestantes adolescentes Riesgo nutricional entre gestantes adolescentes Nutritional risks among pregnant teenagers

    Directory of Open Access Journals (Sweden)

    Glayriann Oliveira Belarmino

    2009-01-01

    Full Text Available OBJETIVOS: Identificar o acometimento de risco nutricional em gestantes adolescentes; averiguar hábitos alimentares; e verificar percepções destes quanto à importância de nutrição adequada na gravidez. MÉTODOS: Estudo de campo realizado no Centro de Desenvolvimento Familiar, em Fortaleza-CE, com 40 gestantes adolescentes. A avaliação nutricional foi efetuada com o auxílio do "Gráfico de acompanhamento nutricional da gestante" e os hábitos alimentares foram conferidos pela "Técnica de alimentação diária habitual". RESULTADOS: Vinte (50% adolescentes apresentaram peso adequado, 11(27,5% baixo peso e 9 (22,5% sobrepeso. Prevaleceram massas, carnes, gorduras, doces e baixo consumo de frutas e verduras; 33 (82,5% tinham a percepção de que a alimentação deve ser "diferente" na gravidez e 28 (70% afirmaram ter feito mudanças nos hábitos alimentares no pré-natal. CONCLUSÃO: O acometimento de risco nutricional entre adolescentes gestantes se revelou em situações de sobrepeso, baixo peso, dietas pouco diversificadas e desinformação.OBJETIVOS: Identificar el riesgo nutricional en gestantes adolescentes; averiguar hábitos alimenticios; y verificar percepciones de éstos en cuanto a la importancia de una nutrición adecuada en el embarazo. MÉTODO: Se trata de un estudio de campo realizado en el Centro de Desarrollo Familiar, en Fortaleza-CE, con 40 gestantes adolescentes. La evaluación nutricional se llevó a cabo con el auxilio del "Gráfico de acompañamiento nutricional de la gestante" y los hábitos alimenticios fueron conferidos por la "Técnica de alimentación diaria habitual". RESULTADOS: Veinte (50% adolescentes presentaron peso adecuado, 11(27,5% bajo peso y 9 (22,5% sobre peso. Prevalecieron pastas, carnes, grasas, dulces y bajo consumo de frutas y verduras; 33 (82,5% tenían la percepción de que la alimentación debe ser "diferente" durante el embarazo y 28 (70% afirmaron haber realizado cambios en los h

  3. Three carbon pairs in Si

    Energy Technology Data Exchange (ETDEWEB)

    Docaj, A. [Physics Department, Texas Tech University, Lubbock, TX 79409-1051 (United States); Estreicher, S.K., E-mail: Stefan.Estreicher@ttu.edu [Physics Department, Texas Tech University, Lubbock, TX 79409-1051 (United States)

    2012-08-01

    Carbon impurities in Si are common in floating-zone and cast-Si materials. The simplest and most discussed carbon complex is the interstitial-substitutional C{sub i}C{sub s} pair, which readily forms when self-interstitials are present in the material. This pair has three possible configurations, each of which is electrically active. The less common C{sub s}C{sub s} pair has been studied in irradiated material but has also recently been seen in as-grown C-rich cast-Si, which is commonly used to fabricate solar cells. The third pair consists of two interstitial C atoms: C{sub i}C{sub i}. Although its formation probability is low for several reasons, the C{sub i}C{sub i} pair is very stable and electrically inactive. In this contribution, we report preliminary results of first-principles calculations of these three C pairs in Si. The structures, binding energies, vibrational spectra, and electrical activity are predicted.

  4. Phonon heat transport in superlattices: Case of Si/SiGe and SiGe/SiGe superlattices

    Science.gov (United States)

    Hijazi, M.; Kazan, M.

    2016-06-01

    We present a predictive Boltzmann model for the cross-plane thermal conductivity in superlattices. The developed model considers particle-like phonons exhibiting wave characteristics at the interfaces and makes the assumption that the phonon heat transport in a superlattice has a mixed character. Exact Boltzmann equation comprising spatial dependence of phonon distribution function is solved to yield a general expression for the lattice thermal conductivity. The intrinsic phonon scattering rates are calculated from Fermi's golden rule, and the model vibrational parameters are derived as functions of temperature and crystallographic directions by using elasticity theory-based lattice dynamics approach. The developed theory is then adapted to calculate the cross-plane thermal conductivity of superlattices. It is assumed that the phonons of wavelengths comparable or smaller than the superlattice period or the root mean square irregularity at the superlattice interfaces may be subject to a resistive scattering mechanism at the interfaces, whereas the phonons of wavelengths much greater than the superlattice period undergo ballistic transmission through the interfaces and obey dispersion relations determined by the Brillouin zone folding effects of the superlattice. The accuracy of the concept of mixed phonon transport regime in superlattices is demonstrated clearly with reference to experimental measurements regarding the effects of period thickness and temperature on the cross-plane thermal conductivity of Si/Si0.7Ge0.3 and Si0.84Ge0.16/Si0.76Ge0.3 superlattices.

  5. Palladium transport in SiC

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, E.J., E-mail: jolivier@nmmu.ac.za [Centre for High Resolution Transmission Electron Microscopy, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Neethling, J.H. [Centre for High Resolution Transmission Electron Microscopy, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer We investigate the reaction of Pd with SiC at typical HTGR operating temperatures. Black-Right-Pointing-Pointer The high temperature mobility of palladium silicides within polycrystalline SiC was studied. Black-Right-Pointing-Pointer Corrosion of SiC by Pd was seen in all cases. Black-Right-Pointing-Pointer The preferential corrosion and penetration of Pd along grain boundaries in SiC was found. Black-Right-Pointing-Pointer The penetration and transport of palladium silicides in SiC along grain boundaries was found. - Abstract: This paper reports on a transmission electron microscopy (TEM) and scanning electron microscopy (SEM) study of Pd corroded SiC. The reaction of Pd with different types of SiC at typical HTGR operating temperatures was examined. In addition the high temperature mobility of palladium silicides within polycrystalline SiC was investigated. The results indicated corrosion of the SiC by Pd in all cases studied. The corrosion leads to the formation of palladium silicides within the SiC, with the predominant phase found being Pd{sub 2}Si. Evidence for the preferential corrosion and penetration of Pd along grain boundaries in polycrystalline SiC was found. The penetration and transport, without significant corrosion, of palladium silicides into polycrystalline SiC along grain boundaries was also observed. Implications of the findings with reference to the use of Tri Isotropic particles in HTGRs will be discussed.

  6. Palladium transport in SiC

    International Nuclear Information System (INIS)

    Highlights: ► We investigate the reaction of Pd with SiC at typical HTGR operating temperatures. ► The high temperature mobility of palladium silicides within polycrystalline SiC was studied. ► Corrosion of SiC by Pd was seen in all cases. ► The preferential corrosion and penetration of Pd along grain boundaries in SiC was found. ► The penetration and transport of palladium silicides in SiC along grain boundaries was found. - Abstract: This paper reports on a transmission electron microscopy (TEM) and scanning electron microscopy (SEM) study of Pd corroded SiC. The reaction of Pd with different types of SiC at typical HTGR operating temperatures was examined. In addition the high temperature mobility of palladium silicides within polycrystalline SiC was investigated. The results indicated corrosion of the SiC by Pd in all cases studied. The corrosion leads to the formation of palladium silicides within the SiC, with the predominant phase found being Pd2Si. Evidence for the preferential corrosion and penetration of Pd along grain boundaries in polycrystalline SiC was found. The penetration and transport, without significant corrosion, of palladium silicides into polycrystalline SiC along grain boundaries was also observed. Implications of the findings with reference to the use of Tri Isotropic particles in HTGRs will be discussed.

  7. Diferencias entre la composición sectorial y ocupacional de las principales ciudades chilenas

    Directory of Open Access Journals (Sweden)

    Marcelo Lufín Varas

    2010-08-01

    Full Text Available La planifcación regional y urbana ha tendido a fjarse exclusivamente en la composición sectorial de las economías locales, asumiendo en forma implícita que la estructura de ocupaciones por actividad es similar a lo largo de un país. Si bien este supuesto parece ser cierto para el conjunto del tejido productivo, se encuentran diferencias signifcativas cuando se analizan ocupaciones específcas. Entre ellas destacan aquellas intensivas en conocimiento, las cuales tienden a estar sobrerrepresen-tadas en las principales ciudades. Se propone una metodología para el análisis de la relación existente entre la estructura de ocupaciones y la estructura sectorial y se aplica al estudio de las principales ciudades chilenas en 2002 a partir de la información del Censo de población, con el objetivo de estimar en qué medida estas estructuras divergen y si existen concentraciones relativas de ocupaciones, observándose que aquellas relacionadas con el conocimiento y la toma de decisiones empresariales tienen una presencia mayor que la esperada en el área metropolitana de Santiago.Regional and urban planning have tended to be exclusively focused on the industrial mix of local economies, implicitly assuming that the occupational mix of economic activities is similar throughout a country. Tis assumption seems to be right fom the perspective of the productive system as a whole, however signifcant diferences arise when analyzing certain occupations. Among them, knowledge-intensive occupations stand out and tend to be overrepresented in the main urban areas. A methodolog y is proposed to analyze the relationship between the occupational and industrial structures. Tis methodology is applied to the case of the principal Chilean cities in 2002 using data fom the population Census in order to estimate the extent to which these structures diverge and whether or not there are relative concentrations of occupations. Results show that the presence of managerial

  8. Relaciones cuantitativas entre los contenidos de azufre y de sulfuros en los aceros inoxidables tipo AISI 303: influencia de la composición química de los sulfuros

    Directory of Open Access Journals (Sweden)

    Botella, J.

    1999-06-01

    Full Text Available The work has been done with ten AISI 303 stainless steel rods which have similar chemical compositions, except for sulphur which varies between 0.25 and 0.36%. These steels are studied by Scanning Electron Microscopy (SEM and Energy Dispersive X-Ray Spectrometry (EDX. The sulphides are chemically microanalysed and the occupied volume determined by automatic image analysis. It can be inferred that the chemical composition of sulphides in AISI 303 steels is variable to some extent even though the steel chemistry is almost invariable. This could mean that solidification conditions and thermomechanical transformations are able to affect resulting in variations of sulphide compositions. Quantitative relations between sulphur and sulphide contents are established and the influence of sulphide chemical compositions on those relations is studied. The experimental results are compared with those obtained from theoretical calculations. A good approach is obtained when the difference between chemical compositions of real sulphides and the theoretical one, MnS, is taken into account.

    Se trabaja con una serie de diez redondos de aceros inoxidables tipo AISI 303 de composiciones químicas prácticamente iguales a excepción del azufre que varía entre 0,25 y 0,36%. Se examinan los aceros mediante Microscopía Electrónica de Barrido (MEB y Espectrometría de Dispersión de Energías de Rayos X (EDX acoplada al MEB, analizándose químicamente los sulfuros y determinando, mediante análisis automático de imágenes, los volúmenes ocupados por los sulfuros. Parece deducible que la composición química de los sulfuros en el AISI 303 puede ser discretamente variable aún siendo prácticamente invariable la composición química del acero. Ello podría significar que las condiciones de solidificación y las transformaciones termomecánicas pueden influir, dando como resultado variaciones en la composición química de los sulfuros. Se establecen

  9. The HFIR 14J irradiation SiC/SiC composite and SiC fiber collaboration

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, G.E.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States); Kohyama, Akira; Katoh, Yutai [Kyoto Univ., Uji, Kyoto (Japan); Hasegawa, Akira [Tohoku Univ., Aramaki, Sendai (Japan); Snead, L. [Oak Ridge National Lab., TN (United States); Scholz, R.

    1998-09-01

    A short introduction with references establishes the current status of research and development of SiC{sub f}/SiC composites for fusion energy systems with respect to several key issues. The SiC fiber and composite specimen types selected for the JUPITER 14J irradiation experiment are presented together with the rationale for their selection.

  10. GeSi/Si Resonant Tunneling Diodes%GeSi/Si共振隧穿二极管

    Institute of Scientific and Technical Information of China (English)

    郭维廉

    2008-01-01

    GeSi/Si共振隧穿二极管主要包括空穴型GeSi/Si RTD、应力型GeSi/Si RTD和GeSi/Si带间共振隧穿二极管三种结构.着重讨论了后两种GeSi/Si基RTD结构;指出GeSi/Si异质结的能带偏差主要发生在二者价带之间(即△Ev>△Ec),形成的电子势阱很浅,因此适用于空穴型RTD的研制;n型带内RTD只有通过应力Si或应力GeSi来实现,这种应力型RTD为带内RTD的主要结构;而带间GeSi/Si RITD则将成为更有应用前景的、性能较好的GeSi/Si RTD器件结构.

  11. Nitrogen doping effect upon hole tunneling characteristics of Si barriers in Si1-xGex/Si resonant tunneling diode

    International Nuclear Information System (INIS)

    Nitrogen atomic-layer (N AL) doping effects upon hole tunneling characteristics of double 4 nm-thick Si barriers in the strained Si1−xGex/Si(100) hole resonant tunneling diode (RTD) were investigated. At a Si cap layer on Si1−xGex(100) (x = 0.2 and 0.4) formed at 500 °C, it was found that NH3 reaction was drastically enhanced at 500 °C especially at the Si cap layer thickness less than 0.5 nm, and the fact indicates a possibility of significant intermixing at the Si/Si1−xGex heterointerface. From current–voltage characteristics of the RTDs, drastic current suppression by N AL doping in the Si barriers can be observed with typical degree of current suppression as high as 103–105 at − 10 mV. Moreover, it was found that N AL doping influences, not only upon such current suppression, but slightly upon negative differential conductance characteristics. - Highlights: • NH3 reaction enhancement on a thin Si cap layer on Si1−xGex(100). • Drastic current suppression by N atomic-layer doping in Si barriers. • N atomic-layer doping effect upon negative differential conductance characteristics

  12. Noms de famille, de baptême et surnoms recensés à Bayonne parmi les ressortissants de la "nation juive du bourg Saint-Esprit" au XVIIIème siècle

    OpenAIRE

    Iglesias, Hector

    2002-01-01

    Etude anthroponymique concernant la communauté juive bayonnaise au XVIIIe siècle. Les archives bayonnaises conservent plusieurs documents du XVIIIe siècle concernant la nation juive du bourg Saint-Esprit . Parmi ces documents, on trouve, entre autres, l'enregistrement par le " Sieur rabbin de la nation Juive du bourg Saint-Esprit près Bayonne " de 219 mariages, de 1184 naissances et de 1140 décès entre 1751 et 1788. Nous avons retranscrit et analysé d'un point de vue onomastique ce corpus. Au...

  13. Correlações entre caracteres quantitativos em milho pipoca Correlation among quantitative traits in popcorn maize

    Directory of Open Access Journals (Sweden)

    Valéria Carpentieri-Pípolo

    2002-12-01

    Full Text Available Em um programa de melhoramento, o conhecimento da grandeza das associações entre caracteres de interesse, é de fundamental importância na obtenção de populações melhoradas. O presente trabalho teve como objetivo determinar as correlações genotípicas, fenotípicas e ambientais entre caracteres quantitativos em milho pipoca. Foram avaliados nove genótipos de milho pipoca dispostos no campo em delineamento em blocos casualizados com oito repetições. Os genótipos UEL ZP, UEL SI e UEL PAP revelaram maiores capacidades de expansão (27,50; 27,15 e 24,40 respectivamente e número de grãos por volume (244,75; 248,50 e 248,75 respectivamente. A capacidade de expansão revelou correlação fenotípica positiva com o tamanho da pipoca e com o número de grãos por volume, e correlação negativa com massa de grãos por planta. Os caracteres massa de grãos por planta e peso total da espiga revelaram correlações fenotípicas e genotípicas positivas entre si, o que possibilita a utilização de um ou outro na seleção, optando-se pelo que melhor convier aos propósitos do programa de melhoramento.Knowledge of the size of the association among traits of interest is of fundamental importance in a breeding program to allow genetic progress. The genotypic, phenotypic and environment correlation were studied among quantitative traits of popcorn maize. Nine popcorn maize genotypes were assessed. A randomized complete block design with eight replications was used. The UEL ZP, UEL SI and UEL PAP. genotypes which had greatest expansion capacity (27.50; 27.15 and 24.20, respectively, also had the greatest values for the number of grains per volume (244.75; 248.50 and 248.75, respectively. The expansion capacity correlated positively with the popcorn size and with number of grains per volume and negatively with plant yield. The traits plant yield, and total ear weight showed positive phenotypic and genotypic correlation that permits the choice of

  14. Comparación entre varias poblaciones estándar para el ajuste por edades

    Directory of Open Access Journals (Sweden)

    Llorca Díaz Javier

    2000-01-01

    Full Text Available FUNDAMENTO: Analizar el efecto que tiene la elección de una población de referencia sobre diferentes indicadores derivados de las tasas de mortalidad ajustadas por edad. MÉTODOS: Las tasas de mortalidad por diferentes causas de muerte en España de 1971 a 1992 son ajustadas empleando cuatro poblaciones de referencia: poblaciones españolas de 1971 y 1992, población estándar europea y población estándar mundial. Los resultados obtenidos con las cuatro poblaciones se comparan empleando tres indicadores: diferencia entre las tasas de 1992 y 1971, razón entre las tasas de 1992 y 1971y cambio anual porcentual entre 1971 y 1992. RESULTADOS: En la mayor parte de las causas de muerte estudiadas incluyendo el total de causas, la cardiopatía isquémica y casi todos los tumores, la razón de tasas y el porcentaje de cambio anual son similares con independencia de cuál sea la población estándar empleada. En cambio, la diferencia de tasas es muy diferente en función de la población de referencia. En las enfermedades infecciosas y el cáncer de testículo se produce la situación contraria: la diferencia de tasas es robusta mientras que la razón de tasas varía con la población estándar. Finalmente, la mortalidad por neumonía, enfermedad de Parkinson y cáncer de encéfalo muestra cambios en los tres indicadores utilizados. CONCLUSIONES: Es necesario realizar un análisis de las tasas específicas por edad antes de proceder a su ajuste. Este análisis permite averiguar si el ajuste por edades es correcto y qué indicador (diferencia, razón o cambio porcentual será adecuado para realizar comparaciones.

  15. Consecuencias de la caída de la fecundidad sobre los intercambios entre generaciones

    Directory of Open Access Journals (Sweden)

    Meil Landwerlin, Gerardo

    2007-12-01

    Full Text Available This article analyzes the effects of the number of siblings and their sex composition as well as other indicators of individualization which are intertwined with the development of a beanpole type kin structure on interchanges among generations in Spain. The effects of this development varies according to the point of view adopted, the parents one or that of the adult children. Though this development increases the probability not to have daughters, there are no clear signs of a weakening of intergenerational ties derived from the development of a beanpole type kin structure. The biggest threat for the density of intergenerational relationships derives not as much from this development, but from the geographical dispersion of the generations caused by the lack of professional and employment opportunities for the younger generations.

    El objeto de este trabajo es analizar los efectos de la caída de la fecundidad sobre los intercambios materiales e inmateriales entre las generaciones (adultas y residentes en hogares independientes en España. El análisis atiende, entre otras variables, al número y a la composición por sexos de la generación más joven, analizando los intercambios entre las díadas hijo varón emancipado / padres e hija emancipada / padres. Los efectos de la caída de la fecundidad y otros cambios familiares asociados a la misma dependen del punto de vista que se adopte, esto es, si se analizan desde el punto de vista de los padres o de los hijos. A pesar de que la caída de la fecundidad aumenta la probabilidad de no tener hijas, no hay signos claros de un debilitamiento de las relaciones intergeneracionales derivadas de la caída de la fecundidad. Las mayores amenazas para la densidad de las relaciones intergeneracionales no derivan tanto de la caída de la fecundidad, como de la dispersión de las generaciones como consecuencia de la ausencia de expectativas laborales y profesionales para la generación más joven en

  16. PARALELO ENTRE LA ACTIVIDAD Y LA SUSTANCIA ADICTIVA DESDE UN ENFOQUE SOCIAL Y SUS POSIBLES TRATAMIENTOS

    Directory of Open Access Journals (Sweden)

    Alan Herzberg

    2007-01-01

    Full Text Available El tema de las adicciones ha sido abordado históric amente por la literatura desde múltiples puntos de vista, sin embargo en esta investigación bibliográfica nuestra intenci ón es dimensionar las teorías sobre el origen de la s adicciones, considerando la complementariedad teórica para la q ue se presta el tema, permitiendo un paralelo con l as terapias psicoanalíticas y la visión freudiana. Por otro lado están los tipos de adicción, entre lo s que se encuentran las directas, que se dirigen ha cia un objeto, y manifiestan un fuerte sentido de control (algunos e jemplos de adicciones de este tipo son el alcoholis mo, cocainomanías, heroinómanas, entre otras, y las in directas, caracterizadas por la búsqueda del placer liberado por las endorfinas en la acción generando un fuerte placer (algunos ejemplos de este tipo de adicciones son la s adicciones al sexo, al juego -ludopatía- y a los servicios de Int ernet entre otros A su vez nos encontramos con los tratamientos, y lo primero que sale a la luz es el tratamiento de alc ohólicos anónimos, donde es digna de analizar la dinámica y calidad de las redes sociales, por otro lado la est ructura de red social y su relación con las diferentes alteracione s y por ultimo el enfoque que se da a la integració n del nuevo abstemio. También se analizan los tratamientos desd e la mirada freudiana, junto con el tratamiento y e l control de adicciones. Pero el punto más importante de todo este análisis es la integración que hemos realizado desde la mira da social, ya que si bien es cierto que las diversas teorías apuntan en muchas formas a una raíz biológica, es el factor social el gatillador, ya que uno de los factores de riesgo que se reconoc e ampliamente en la literatura es la red social, as í como también dentro de los tipos de adicción se puede ver que la división que realizamos se basa exclusivamente en el locus de control, y por último se perciben en los tratamient os m

  17. Obtenção de substratos cerâmicos no sistema Si-Al-O-N-C empregando polissiloxanos e carga de Si e Al2O3 Ceramic tapes of Si-Al-O-N-C compounds using mixtures of polyssiloxane and Si-Al2O3 fillers

    Directory of Open Access Journals (Sweden)

    R. M. Rocha

    2005-03-01

    Full Text Available A técnica de processamento de colagem por fita (tape casting tem sido amplamente utilizada na obtenção de cerâmicas para diferentes aplicações: substratos cerâmicos e estruturas planares em multicamadas para circuitos integrados e capacitores; eletrólitos sólidos para células a combustível e sensores; cerâmicas piezoelétricas para atuadores e transdutores; membranas de separação para micro-filtragem; compósitos estruturais e trocadores de calor. Neste trabalho, a técnica convencional de colagem por fita foi adaptada com a utilização do processo de pirólise controlada de misturas de polímeros e carga, empregando-se polissiloxanos e cargas de silício e alumina nas suspensões. Foram preparadas suspensões com 60% vol. de fase polimérica (polissiloxanos e metil-trietoxi-silano e 40% vol. de carga (Si e Al2O3, com diferentes concentrações dos polímeros e das cargas. As amostras na forma de substratos foram pirolisadas em atmosfera de nitrogênio a 1400 °C/2 h e 1500 °C/2 h, sendo convertidas em materiais cerâmicos no sistema Si-Al-O-N-C. O processo de pirólise foi caracterizado até a temperatura de 1000 ºC por análise termogravimétrica. As cerâmicas foram caracterizadas quanto às fases formadas, microestrutura, massa específica aparente e condutividade térmica. Os substratos cerâmicos apresentaram porosidade relativamente alta (entre 12 e 22% e baixa condutividade térmica (entre 3 e 8 W/m.K, sendo constituídos por fases cristalinas de beta-SiC, Si2ON2, O'-SiAlON, Al2O3, mulita e fase amorfa de SiOC; o Si foi observado nas amostras pirolisadas a 1400 ºC.The tape casting technique has been widely used to prepare ceramic tapes for different applications: ceramic substrates and multilayer planar structures for integrated circuits and capacitors, solid electrolytes for fuel cells and sensors, piezoelectric ceramics for actuators and transducers, membrane systems for micro-filtration, structural composites and

  18. DERRIDA E BARTHES: POR ENTRE SINGULARIDADES E PLURALIDADES

    Directory of Open Access Journals (Sweden)

    Raquel Campos

    2015-12-01

    Full Text Available Através da homenagem feita por Derrida a Barthes em seu ensaio “As mortes de Roland Barthes”, o artigo pretende traçar os pontos de encontro entre os dois pensadores em meio à pluralidade de suas ideias e na singularidade das mesmas. “Essa singularidade penetrada me alcança de um golpe, me fere ou me assassina e, em princípio, parece olhar diretamente para mim. […] A mim se dirige a singularidade absoluta do outro” (2008, p.275, como afirma Derrida em seu ensaio. Os pontos intransponíveis entre um indivíduo e outro criam as singularidades, ao mesmo tempo em que contribuem, aporeticamente, à pluralidade de caminhos, possibilidades e ideias. O aparente paradoxo entre esses dois pontos e a coexistência de ambos em um mesmo espaço serão analisados, na tentativa de encontrar consonâncias entre dois tão importantes pensadores, distintos, mas que, por vezes, trabalharam em suas respectivas obras com questões similares.

  19. Estudio de Impacto Ambiental de la Remodelación de la Carretera AB-519 entre los términos municipales de Casas de Lázaro y Peñarrubia (Provincia de Albacete).

    OpenAIRE

    GARCÍA ALCALÁ, ENRIQUE

    2016-01-01

    [ES] Se ha procedido a la redacción del Estudio de Impacto ambiental de la Remodelación de la Carretera AB-519 entre los términos municipales de Casas de Lázaro y Peñarrubia (Provincia de Albacete), que consiste en: Remodelar la carretera que conecta el municipio de Casas de Lázaro con el municipio de Peñarrubia. Se tiene que estudiar si la propuesta es viable medioambientalmente o si sería mejor no realizar ninguna actuación y dejar la infraestructura como está. Este proyecto incrementará la...

  20. Emission efficiency limit of Si nanocrystals

    NARCIS (Netherlands)

    Limpens, R.; Luxembourg, S.L.; Weeber, A.W.; Gregorkiewicz, T.

    2016-01-01

    One of the important obstacles on the way to application of Si nanocrystals for development of practical devices is their typically low emissivity. In this study we explore the limits of external quantum yield of photoluminescence of solid-state dispersions of Si nanocrystals in SiO2. By making use

  1. High Q SiC microresonators

    OpenAIRE

    Cardenas, Jaime; Zhang, Mian; Phare, Christopher T.; Shah, Shreyas Y.; Poitras, Carl B.; Lipson, Michal

    2013-01-01

    We demonstrate photonic devices based on standard 3C SiC epitaxially grown on silicon. We achieve high optical confinement by taking advantage of the high stiffness of SiC and undercutting the underlying silicon substrate. We demonstrate a 20 um radius suspended microring resonator with Q of 18000 fabricated on commercially available SiC-on-silicon substrates.

  2. Microwave joining of SiC

    Energy Technology Data Exchange (ETDEWEB)

    Silberglitt, R.; Ahmad, I. [FM Technologies, Inc., Fairfax, VA (United States); Black, W.M. [George Mason Univ., Fairfax, VA (United States)] [and others

    1995-05-01

    The purpose of this work is to optimize the properties of SiC-SiC joints made using microwave energy. The current focus is on optimization of time-temperature profiles, production of SiC from chemical precursors, and design of new applicators for joining of long tubes.

  3. 3C-SiC nanocrystal growth on 10° miscut Si(001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Deokar, Geetanjali, E-mail: gitudeo@gmail.com [INSP, UPMC, CNRS UMR 7588, 4 place Jussieu, Paris F-75005 (France); D' Angelo, Marie; Demaille, Dominique [INSP, UPMC, CNRS UMR 7588, 4 place Jussieu, Paris F-75005 (France); Cavellin, Catherine Deville [INSP, UPMC, CNRS UMR 7588, 4 place Jussieu, Paris F-75005 (France); Faculté des Sciences et Technologie UPEC, 61 av. De Gaulle, Créteil F-94010 (France)

    2014-04-01

    The growth of 3C-SiC nano-crystal (NC) on 10° miscut Si(001) substrate by CO{sub 2} thermal treatment is investigated by scanning and high resolution transmission electron microscopies. The vicinal Si(001) surface was thermally oxidized prior to the annealing at 1100 °C under CO{sub 2} atmosphere. The influence of the atomic steps at the vicinal SiO{sub 2}/Si interface on the SiC NC growth is studied by comparison with the results obtained for fundamental Si(001) substrates in the same conditions. For Si miscut substrate, a substantial enhancement in the density of the SiC NCs and a tendency of preferential alignment of them along the atomic step edges is observed. The SiC/Si interface is abrupt, without any steps and epitaxial growth with full relaxation of 3C-SiC occurs by domain matching epitaxy. The CO{sub 2} pressure and annealing time effect on NC growth is analyzed. The as-prepared SiC NCs can be engineered further for potential application in optoelectronic devices and/or as a seed for homoepitaxial SiC or heteroepitaxial GaN film growth. - Highlights: • Synthesis of 3C-SiC nanocrystals epitaxied on miscut-Si using a simple technique • Evidence of domain matching epitaxy at the SiC/Si interface • SiC growth proceeds along the (001) plane of host Si. • Substantial enhancement of the SiC nanocrystal density due to the miscut • Effect of the process parameters (CO{sub 2} pressure and annealing duration)

  4. Ultrasound assisted siRNA delivery using PEG-siPlex loaded microbubbles.

    Science.gov (United States)

    Vandenbroucke, Roosmarijn E; Lentacker, Ine; Demeester, Joseph; De Smedt, Stefaan C; Sanders, Niek N

    2008-03-20

    Short interfering RNA (siRNA) attracts much attention for the treatment of various diseases. However, its delivery, especially via systemic routes, remains a challenge. Indeed, naked siRNAs are rapidly degraded, while complexed siRNAs massively aggregate in the blood or are captured by macrophages. Although this can be circumvented by PEGylation, we found that PEGylation had a strong negative effect on the gene silencing efficiency of siRNA-liposome complexes (siPlexes). Recently, ultrasound combined with microbubbles has been used to deliver naked siRNA but the gene silencing efficiency is rather low and very high amounts of siRNA are required. To overcome the negative effects of PEGylation and to enhance the efficiency of ultrasound assisted siRNA delivery, we coupled PEGylated siPlexes (PEG-siPlexes) to microbubbles. Ultrasound radiation of these microbubbles resulted in massive release of unaltered PEG-siPlexes. Interestingly, PEG-siPlexes loaded on microbubbles were able to enter cells after exposure to ultrasound, in contrast to free PEG-siPlexes, which were not able to enter cells rapidly. Furthermore, these PEG-siPlex loaded microbubbles induced, in the presence of ultrasound, much higher gene silencing than free PEG-siPlexes. Additionally, the PEG-siPlex loaded microbubbles only silenced the expression of genes in the presence of ultrasound, which allows space and time controlled gene silencing.

  5. Laser cladding of Al-Si/SiC composite coatings : Microstructure and abrasive wear behavior

    NARCIS (Netherlands)

    Anandkumar, R.; Almeida, A.; Vilar, R.; Ocelik, V.; De Hosson, J.Th.M.

    2007-01-01

    Surface coatings of an Al-Si-SiC composite were produced on UNS A03560 cast Al-alloy substrates by laser cladding using a mixture of powders of Al-12 wt.% Si alloy and SiC. The microstructure of the coatings depends considerably on the processing parameters. For a specific energy of 26 MJ/m2 the mic

  6. Microstructure and wear studies of laser clad Al-Si/SiC(p) composite coatings

    NARCIS (Netherlands)

    Anandkumar, R.; Almeida, A.; Colaco, R.; Vilar, R.; Ocelik, V.; De Hosson, J. Th. M.

    2007-01-01

    Coatings of a composite material consisting of an Al-Si matrix reinforced with SiC particles were produced by laser cladding on UNS A03560 cast Al-alloy substrates from mixtures of powders of Al-12 wt.% Si alloy and SiC. The influence of the processing parameters on the microstructure and abrasive w

  7. Irradiation project of SiC/SiC fuel pin 'INSPIRE': Status and future plan

    International Nuclear Information System (INIS)

    After the March 11 Disaster in East-Japan, Research and Development towards Ensuring Nuclear Safety Enhancement for LWR becomes a top priority R and D in nuclear energy policy of Japan. The role of high temperature non-metallic materials, such as SiC/SiC, is becoming important for the advanced nuclear reactor systems. SiC fibre reinforced SiC composite has been recognised to be the most attractive option for the future, now, METI fund based project, INSPIRE, has been launched as 5-year termed project at OASIS in Muroran Institute of Technology aiming at early realisation of this system. INSPIRE is the irradiation project of SiC/SiC fuel pins aiming to accumulate material, thermal, irradiation effect data of NITE-SiC/SiC in BWR environment. Nuclear fuel inserted SiC/SiC fuel pins are planned to be installed in the Halden reactor. The project includes preparing the NITE-SiC/SiC tubes, joining of end caps, preparation of rigs to control the irradiation environment to BWR condition and the instruments to measure the condition of rigs and pins in operation. Also, basic neutron irradiation data will be accumulated by SiC/SiC coupon samples currently under irradiation in BR2. The output from this project may present the potentiality of NITE-SiC/SiC fuel cladding with the first stage fuel-cladding interaction. (authors)

  8. L’héritage de la principauté d’Orange. Enjeu entre le protecteur des Provinces-Unies et le roi de France

    OpenAIRE

    Porte, Rémy

    2008-01-01

    Mal connue, l’histoire de la principauté d’Orange ne relève pas d’une histoire locale ou régionale traditionnelle. Paradoxalement, alors que sa superficie n’a jamais été considérable, la ville doit à sa position géographique et à un héritage complexe de jouer pendant cinq siècles un rôle important entre le royaume de France et le Saint- Empire germanique, puis entre catholiques et prostestants. Parallèlement aux différentes interventions prononcées aujourd’hui sur les relations franco-irlanda...

  9. La Interacción Mutua entre Fuentes y las Aparentes Anomalías en el Fenómeno de Interferencia

    Directory of Open Access Journals (Sweden)

    Reinaldo Welti

    2002-01-01

    Full Text Available En la mayoría de los textos de física del nivel básico universitario al tratar el fenómeno de interferencia suponen que las fuentes irradian de la misma forma cualquiera sea la distancia entre ellas. En algunas situaciones esta suposición puede llevar a aparentes anomalías en la conservación de la energía. En este trabajo se muestra que estas anomalías se resuelven solamente si el fenómeno de interferencia se presenta en un contexto que tenga en cuenta las interacciones entre las fuentes y el generador que suministra energía a las mismas.

  10. Diferencias del clima laboral entre empleados contratados por outsourcing y empleados directos: evidencia empírica de la zona norte de Colombia.

    Directory of Open Access Journals (Sweden)

    David Juliao Esparragoza

    2014-12-01

    Full Text Available Son pocos los estudios empíricos sobre clima laboral en Colombia que muestran las diferencias entre grupos de trabajadores que, teniendo las mismas funciones en la empresa, cuentan con diferentes tipos de contrato. Esta investigación, a partir de un estudio realizado con empleados de una importante empresa de bebidas ubicada en la costa norte de Colombia, trata de aportar a la resolución de esta carencia, verificando si existen diferencias significativas, en algunas variables del clima laboral, entre los grupos de trabajadores contratados directamente y aquellos vinculados por prestación de servicios. El trabajo es de tipo descriptivo y transversal, se apoya en el método hipotético inductivo y utiliza el instrumento imcoc (evaluando las diferencias inter-grupales en las seis variables que lo componen, a saber: objetivos, cooperación, liderazgo, toma de decisiones, relaciones interpersonales, motivación y control.

  11. Características individuales y actitudes discriminatorias hacia la mujer en México: ¿existen diferencias entre las regiones?

    Directory of Open Access Journals (Sweden)

    Juan José Argaez

    2011-01-01

    Full Text Available Con base en los resultados de la Primera encuesta nacional sobre discriminación en México, en este artículo se examina la relación entre factores individuales y las actitudes discriminatorias hacia la mujer. El objetivo es evaluar empíricamente la influencia de estos factores en lo individual, y descubrir si existe alguna diferencia entre las regiones que lleve a la persistencia de actitudes discriminatorias. Los resultados concuerdan con las expectativas en cuanto a los factores individuales, y revelan que los habitantes del norte y centro de México mantienen actitudes discriminatorias más intensas que la población del sur del país.

  12. INNOVACIÓN EN EL DISEÑO Y EVALUACIÓN DE PROYECTOS: ESTABLECIMIENTO DE LAS RELACIONES LINGÜÍSTICAS ENTRE OBJETIVOS Y PROBLEMAS

    Directory of Open Access Journals (Sweden)

    CARLOS MARIO ZAPATA JARAMILLO

    2011-12-01

    Full Text Available El lenguaje desempeña un papel importante en el diseño y evaluación de proyectos, especialmente cuando se trata de identificar y enunciar problemas y objetivos. Aunque no se propone formalmente, en algunos ámbitos se reconoce que existen estructuras para expresar objetivos y problemas ligados con una organización. Sin embargo, no se suele plantear una relación directa entre ellas o, si se requiere, se plantean de forma intuitiva. Esta relación es importante porque permite a los miembros de la organización plantear soluciones a los problemas que se liguen con sus objetivos estratégicos. Por ello, en este artículo se presenta una propuesta innovadora para establecer las relaciones lingüísticas entre los problemas de una organización y sus objetivos. Además se muestran algunos ejemplos.

  13. Un pequeño aumento en el espaciado entre letras favorece la lectura en niños disléxicos

    Directory of Open Access Journals (Sweden)

    Victoria Panadero

    2012-09-01

    Full Text Available Varias investigaciones recientes han mostrado que un ligero aumento del espaciado entre las letras (respecto al espaciado estándar produce tiempos de lectura más rápidos en los niños con dislexia, así como mejoras en la comprensión de los textos. Si bien el aumento en el espaciado de las letras no “cura” la dislexia, sí permite una mejora en el proceso de lectura. Es importante remarcar que la posibilidad de modificar el espaciado entre letras se encuentra disponible en los programas de procesamiento de texto. Creemos que dicha opción debería estar disponible próximamente en los libros electrónicos.

  14. Efficient Silicon Light-Emitting-Diodes with a p-Si/Ultrathin SiO2/n-Si Structure

    Directory of Open Access Journals (Sweden)

    Shucheng Chu

    2011-01-01

    Full Text Available We report the efficient enhancement of light emission from silicon crystal by covering the silicon surface with an ultrathin (several nm SiO2 layer. The photoluminescence of Si band edge emission (1.14 μm band at room temperature is enhanced by two orders of magnitude. Compared with a p-Si/n-Si diode, light emission from a p-Si/SiO2/n-Si diode by current injection via direct tunneling is enhanced by more than 3 orders of magnitude. The light-emission enhancement is attributed to the diminishment of nonradiation recombination at the surface/interface and to the space confinement of the carrier recombination. The simple structure and low operating bias (approximately 1 volt of our light emitting diodes supply a new choice for realizing efficient current injection light source in silicon compatible with conventional ULSI technology.

  15. Abrupt GaP/Si hetero-interface using bistepped Si buffer

    Energy Technology Data Exchange (ETDEWEB)

    Ping Wang, Y., E-mail: yanping.wang@insa-rennes.fr; Kuyyalil, J.; Nguyen Thanh, T.; Almosni, S.; Bernard, R.; Tremblay, R.; Da Silva, M.; Létoublon, A.; Rohel, T.; Tavernier, K.; Le Corre, A.; Cornet, C.; Durand, O. [UMR FOTON, CNRS, INSA Rennes, Rennes F-35708 (France); Stodolna, J.; Ponchet, A. [CEMES-CNRS, Université de Toulouse, 29 rue Jeanne Marvig, BP 94347, 31055 Toulouse Cedex 04 (France); Bahri, M.; Largeau, L.; Patriarche, G. [Laboratoire de Photonique et Nanostructures, CNRS UPR 20, Route de Nozay, Marcoussis 91460 (France); Magen, C. [LMA, INA-ARAID, and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza (Spain)

    2015-11-09

    We evidence the influence of the quality of the starting Si surface on the III-V/Si interface abruptness and on the formation of defects during the growth of III-V/Si heterogeneous crystal, using high resolution transmission electron microscopy and scanning transmission electron microscopy. GaP layers were grown by molecular beam epitaxy on vicinal Si (001). The strong effect of the Si substrate chemical preparation is first demonstrated by studying structural properties of both Si homoepitaxial layer and GaP/Si heterostructure. It is then shown that choosing adequate chemical preparation conditions and subsequent III-V regrowth conditions enables the quasi-suppression of micro-twins in the epilayer. Finally, the abruptness of GaP/Si interface is found to be very sensitive to the Si chemical preparation and is improved by the use of a bistepped Si buffer prior to III-V overgrowth.

  16. Si quantum dot structures and their applications

    Science.gov (United States)

    Shcherbyna, L.; Torchynska, T.

    2013-06-01

    This paper presents briefly the history of emission study in Si quantum dots (QDs) in the last two decades. Stable light emission of Si QDs and NCs was observed in the spectral ranges: blue, green, orange, red and infrared. These PL bands were attributed to the exciton recombination in Si QDs, to the carrier recombination through defects inside of Si NCs or via oxide related defects at the Si/SiOx interface. The analysis of recombination transitions and the different ways of the emission stimulation in Si QD structures, related to the element variation for the passivation of surface dangling bonds, as well as the plasmon induced emission and rare earth impurity activation, have been presented. The different applications of Si QD structures in quantum electronics, such as: Si QD light emitting diodes, Si QD single union and tandem solar cells, Si QD memory structures, Si QD based one electron devices and double QD structures for spintronics, have been discussed as well. Note the significant worldwide interest directed toward the silicon-based light emission for integrated optoelectronics is related to the complementary metal-oxide semiconductor compatibility and the possibility to be monolithically integrated with very large scale integrated (VLSI) circuits. The different features of poly-, micro- and nanocrystalline silicon for solar cells, that is a mixture of both amorphous and crystalline phases, such as the silicon NCs or QDs embedded in a α-Si:H matrix, as well as the thin film 2-cell or 3-cell tandem solar cells based on Si QD structures have been discussed as well. Silicon NC based structures for non-volatile memory purposes, the recent studies of Si QD base single electron devices and the single electron occupation of QDs as an important component to the measurement and manipulation of spins in quantum information processing have been analyzed as well.

  17. Swarm Intelligence (SI) in Manufacturing

    OpenAIRE

    Molinuevo, Javier Toral

    2010-01-01

    Manufacturing is a field of Engineering which is constantly changing. Due to this fact more and more complicated problems appear and have to be solved by engineers. Some of them are difficult to solve by usual numerical methods, as equations, so a new area is developing at present using Artificial Intelligence (AI) techniques.There are many different tools like Genetic Algorithms, Fuzzy Logic Systems… but in this thesis we are going to focus on the Swarm Intelligence (SI) which tries to mimic...

  18. Nanoporosity of Si (100) bars

    Science.gov (United States)

    Novikov, S. N.; Timoshenkov, S. P.; Minaev, V. S.; Goryunova, E. P.; Gerasimenko, N. N.; Smirnov, D. I.

    2016-09-01

    Si(100) samples cut from a typical bar (100 mm in diameter) prepared using industrial technology are studied. Measurements of the electron work function (EWF) show that the size effects in these samples (a reduction in thickness along with a sample's area and the EWF) detected earlier were due to nanostructure porosity that was buried by the technological treatment of a bar's surface. This hidden nanoporosity is assumed to be a manifestation of the secondary crystal structure.

  19. Formation of Si/SiC multilayers by low-energy ion implantation and thermal annealing

    NARCIS (Netherlands)

    Dobrovolskiy, S.; Yakshin, A.E.; Tichelaar, F.D.; Verhoeven, J.; Louis, E.; Bijkerk, F.

    2010-01-01

    Si/SiC multilayer systems for XUV reflection optics with a periodicity of 10–20 nm were produced by sequential deposition of Si and implantation of 1 keV View the MathML source ions. Only about 3% of the implanted carbon was transferred into the SiC, with a thin, 0.5–1 nm, buried SiC layer being fo

  20. Current–voltage studies on -FeSi2/Si heterojunction

    Indian Academy of Sciences (India)

    A Datta; S Kal; S Basu

    2000-08-01

    – characteristics of both -FeSi2/n-Si and -FeSi2/p-Si were studied at room temperature. The junctions were formed by depositing Fe on Si selectively followed by thermal annealing and some samples were later treated by pulsed laser. Temperature of thermal annealing and diode area were also varied. – studies on all these samples were done and ideality factors were computed. Results obtained were interpreted.

  1. Stability analysis of SiO2/SiC multilayer coatings

    International Nuclear Information System (INIS)

    The stability behaviours of SiC coatings and SiO2/SiC coatings in helium with little impurities are studied by HSC Chemistry 4.1, the software for analysis of Chemical reaction and equilibrium in multi-component complex system. It is found that in helium with a low partial pressure of oxidative impurities under different total pressure, the key influence factor controlling Tcp of SiC depends is the partial pressure of oxidative impurities; Tcp of SiC increases with the partial pressure of oxidative impurities. In helium with a low partial pressure of different impurities, the key influence factor of Tcs of SiO2 are both the partial pressure of impurities and the amount of impurities for l mol SiO2; Tcs of SiO2 increases with the partial pressure of oxidative impurities at the same amount of the impurities for 1 mol SiO2 while it decreases with the amount of the impurities for 1 mm SiO2 at the same partial pressure of the impurities. The influence of other impurities on Tcp of SiC in He-O2 is studied and it is found that CO2, H2O and N-2 increase Tcp of SiC in He-O2 while H2, CO and CH4 decrease Tcp of SiC He-O2. When there exist both oxidative impurities and reductive impurities, their effect on Tcs of SiO2 can be suppressed by the other. In HTR-10 operation atmosphere, SiO2/SiC coatings can keep stable status at higher temperature than SiC coatings, so SiO2/SiC coatings is more suitable to improve the oxidation resistance of graphite in HTR-10 operation atmosphere compared with SiC coatings. (authors)

  2. Effect of Si interface surface roughness to the tunneling current of the Si/Si1-xGex/Si heterojunction bipolar transistor

    Science.gov (United States)

    Hasanah, Lilik; Suhendi, Endi; Tayubi, Yuyu Rahmat; Yuwono, Heru; Nandiyanto, Asep Bayu Dani; Murakami, Hideki; Khairrurijal

    2016-02-01

    In this work we discuss the surface roughness of Si interface impact to the tunneling current of the Si/Si1-xGex/Si heterojunction bipolar transistor. The Si interface surface roughness can be analyzed from electrical characteristics through the transversal electron velocity obtained as fitting parameter factor. The results showed that surface roughness increase as Ge content of virtual substrate increase This model can be used to investigate the effect of Ge content of the virtual substrate to the interface surface condition through current-voltage characteristic.

  3. Effect of Si interface surface roughness to the tunneling current of the Si/Si{sub 1-x}Ge{sub x}/Si heterojunction bipolar transistor

    Energy Technology Data Exchange (ETDEWEB)

    Hasanah, Lilik, E-mail: lilikhasanah@upi.edu; Suhendi, Endi; Tayubi, Yuyu Rahmat; Yuwono, Heru [Department of Physics Education, Universitas Pendidikan Indonesia, Jl. Setiabudhi 229 Bandung 40154 (Indonesia); Nandiyanto, Asep Bayu Dani [Department Kimia, Universitas Pendidikan Indonesia, Jl. Setiabudhi 229 Bandung 40154 (Indonesia); Murakami, Hideki [Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8527 (Japan); Khairrurijal [Physics of Electronic Materials Research Division, Institut Teknologi Bandung, Bandung 40132 (Indonesia)

    2016-02-08

    In this work we discuss the surface roughness of Si interface impact to the tunneling current of the Si/Si{sub 1-x}Ge{sub x}/Si heterojunction bipolar transistor. The Si interface surface roughness can be analyzed from electrical characteristics through the transversal electron velocity obtained as fitting parameter factor. The results showed that surface roughness increase as Ge content of virtual substrate increase This model can be used to investigate the effect of Ge content of the virtual substrate to the interface surface condition through current-voltage characteristic.

  4. Active Oxidation of SiC

    Science.gov (United States)

    Jacobson, Nathan S.; Myers,Dwight L.; Harder, Bryan J.

    2011-01-01

    The high temperature oxidation of silicon carbide occurs in either a passive or active mode, depending on temperature and oxygen potential. Passive oxidation forms a protective oxide film which limits attack of the SiC:SiC(s) + 3/2 O2(g) = SiO2(s) + CO(g.) Active oxidation forms a volatile oxide and leads to extensive attack of the SiC: SiC(s) + O2(g) = SiO(g) + CO(g). The transition points and rates of active oxidation are a major issue. Previous studies are reviewed and the leading theories of passive/active transitions summarized. Comparisons are made to the active/passive transitions in pure Si, which are relatively well-understood. Critical questions remain about the difference between the active-to-passive transition and passive-to-active transition. For Si, Wagner [2] points out that the active-to-passive transition is governed by the criterion for a stable Si/SiO2 equilibria and the passive-to-active transition is governed by the decomposition of the SiO2 film. This suggests a significant oxygen potential difference between these two transitions and our experiments confirm this. For Si, the initial stages of active oxidation are characterized by the formation of SiO(g) and further oxidation to SiO2(s) as micron-sized rods, with a distinctive morphology. SiC shows significant differences. The active-to-passive and the passive-to-active transitions are close. The SiO2 rods only appear as the passive film breaks down. These differences are explained in terms of the reactions at the SiC/SiO2 interface. In order to understand the breakdown of the passive film, pre-oxidation experiments are conducted. These involve forming dense protective scales of 0.5, 1, and 2 microns and then subjecting the samples with these scales to a known active oxidation environment. Microstructural studies show that SiC/SiO2 interfacial reactions lead to a breakdown of the scale with a distinct morphology.

  5. Lattice dislocation in Si nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Omar, M.S., E-mail: dr_m_s_omar@yahoo.co [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq); Taha, H.T. [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq)

    2009-12-15

    Modified formulas were used to calculate lattice thermal expansion, specific heat and Bulk modulus for Si nanowires with diameters of 115, 56, 37 and 22 nm. From these values and Gruneisen parameter taken from reference, mean lattice volumes were found to be as 20.03 A{sup 3} for the bulk and 23.63, 29.91, 34.69 and 40.46 A{sup 3} for Si nanowire diameters mentioned above, respectively. Their mean bonding length was calculated to be as 0.235 nm for the bulk and 0.248, 0.269, 0.282 and 0.297 nm for the nanowires diameter mentioned above, respectively. By dividing the nanowires diameter on the mean bonding length, number of layers per each nanowire size was found to be as 230, 104, 65 and 37 for the diameters mentioned above, respectively. Lattice dislocations in 22 nm diameter wire were found to be from 0.00324 nm for the 1st central lattice to 0.2579 nm for the last surface lattice. Such dislocation was smaller for larger wire diameters. Dislocation concentration found to change in Si nanowires according to the proportionalities of surface thickness to nanowire radius ratios.

  6. Porous SiC/SiC composites development for industrial application

    International Nuclear Information System (INIS)

    Silicon carbide (SiC) is promising structural materials in nuclear fields due to an excellent irradiation resistance and low activation characteristics. Conventional SiC fibers reinforced SiC matrix (SiC/SiC composites) fabricated by liquid phase sintering (LPS-SiC/SiC composites) have been required high cost and long processing time. And microstructure and mechanical property data of finally obtained LPS-SiC/SiC composites are easily scattered, because quality of the composites depend on personal skill. Thus, conventional LPS-SiC/SiC composites are inadequate for industrial use. In order to overcome these issues, the novel “porous SiC/SiC composites” have been developed by means of liquid phase sintering fabrication process. The composites consist of porous SiC matrix and SiC fibers without conventional carbon interfacial layer. The composites don’t have concerns of the degradation interfacial layer at the severe accident. Porous SiC/SiC composites preform was prepared with a thin sheet shape of SiC, sintering additives and carbon powder mixture by tape casting process which was adopted because of productive and high yielding rate fabrication process. The preform was stacked with SiC fibers and sintered in hot-press at the high temperature in argon environment. The sintered preform was decarburized obtain porous matrix structure by heat-treatment in air. Moreover, mechanical property data scattering of the obtained porous SiC/SiC composites decreased. In the flexural test, the porous SiC/SiC composites showed pseudo-ductile behavior with sufficient strength even after heat treatment at high temperature in air. From these conclusions, it was proven that porous SiC/SiC composites were reliable material at severe environment such as high temperature in air, by introducing tape casting fabrication process that could produce reproducible materials with low cost and simple way. Therefore development of porous SiC/SiC composites for industrial application was

  7. Imaginar con tecnologías: relaciones entre tecnologías y conocimiento

    Directory of Open Access Journals (Sweden)

    Depetris, Beatriz

    2006-01-01

    Full Text Available La masiva inclusión de tecnologías en los procesos de enseñanza y de aprendizaje no está, muchas veces, precedida de la necesaria reflexión sobre los tiempos, los modos y los contextos en los que deben incorporarse. Es por ello que todo aporte que la incentive resulta sumamente valioso. Carina Lion es Doctora en Educación de la Universidad de Buenos Aires, Especialista en Formación de Formadores, Licenciada y Profesora en Ciencias de la Educación de la Facultad de Filosofía y Letras de la Universidad de Buenos Aires. Ha desarrollado una importante trayectoria docente en las áreas de educación a distancia y educación y tecnologías. Si bien este libro constituye su primera producción individual, son variadas sus publicaciones sobre las complejas relaciones entre tecnología y educación, tanto en obras colectivas como en revistas (con y sin referato, abarcando tanto cuestiones académicas como de difusión.

  8. Estudio sobre las relaciones filogenéticas entre diversos aislamientos del hongo Paracoccidioides brasiliensis

    Directory of Open Access Journals (Sweden)

    Juan McEwen

    2003-01-01

    Full Text Available Aunque es poco lo que se conoce acerca de la biología evolutiva
    del hongo P. brasiliensis, varios estudios moleculares han demostrado que existen variaciones en secuencias de ADN entre sus aislamientos, las que se correlacionan con el origen geográfico de las mismas y con diferencias en su virulencia para modelos murinos (1,2. Se desconoce si estas variaciones son el resultado final de un proceso de especiación alopátrica que daría origen a especies aisladas genéticamente provistas de características fenotípicas (patogenicidad, inmunogenicidad y genotípicas diferentes, las que podrían ser usadas como una alternativa para mejorar e innovar los métodos actuales de diagnóstico. Por lo tanto, proponemos como objetivo general estudiar un aspecto fundamental de la biología evolutiva del hongo patógeno humano P. brasiliensis como es la especiación.

  9. Las relaciones especiales de sujeción entre el Estado y sus funcionarios

    Directory of Open Access Journals (Sweden)

    Luis Eduardo Ardila Quiroz

    2012-01-01

    Full Text Available Este escrito hace alusión a relaciones que existe entre el Estado y sus funcionarios, desde la obediencia en Grecia, hasta la connotación que adquiere el servidor público en el Estado Social de Derecho; y a su vez, las de estos para con sus asociados, pues bien sabido es que quienes sostienen al Estado y a todo el personal necesario para la exteriorización de aquel, son quienes pagan impuestos y contribuyen para que el presupuesto de gastos en bienes y servicios lleguen a buen puerto.Así como existen obligaciones por parte del Estado, también existen deberes que cumplir por parte de quienes lo habitan, por eso es de obligatorio cumplimiento, so pena de incurrir en un delito, el pago de contribuciones a favor del Estado, pero para que las erogaciones por parte del Estado hacia su población tengan la teleología o el fin propuesto, es necesario de una buena administración, si ello no acontece, se pierde la filosofía de las buenas maneras.

  10. CIUDADANÍA FISCAL Y NUEVAS FORMAS DE RELACIÓN ENTRE CONTRIBUYENTES Y ADMINISTRACIÓN TRIBUTARIA

    Directory of Open Access Journals (Sweden)

    Alejandro M. Estévez

    2009-01-01

    Full Text Available Usualmente, el cumplimiento fiscal ha sido explicado por el riesgo de la coerción. Este artículo analiza la nueva orientación de las administraciones tributarias, a fin de comprender cómo este hecho puede alentar la cultura tributaria de las sociedades, a través de la autorregulación y el cumplimiento voluntario. Aunque la mejora de la relación entre administración tributaria y el contribuyente no asegura en su totalidad, ni es la única manera para lograr el cumplimiento tributario, si constituye un factor determinante para aumentar la voluntad de cooperación de cada contribuyente y su intención en colaborar con su esfuerzo individual al sostenimiento de una sociedad general.

  11. Diferencias del clima laboral entre empleados contratados por outsourcing y empleados directos: evidencia empírica de la zona norte de Colombia.

    OpenAIRE

    David Juliao Esparragoza; Ciro Sánchez Bejarano; Domingo Martínez Díaz

    2014-01-01

    Son pocos los estudios empíricos sobre clima laboral en Colombia que muestran las diferencias entre grupos de trabajadores que, teniendo las mismas funciones en la empresa, cuentan con diferentes tipos de contrato. Esta investigación, a partir de un estudio realizado con empleados de una importante empresa de bebidas ubicada en la costa norte de Colombia, trata de aportar a la resolución de esta carencia, verificando si existen diferencias significativas, en algunas variables del clima labora...

  12. TRANSFERENCIA DE FUNCIONES SINTÁCTICAS ARTIFICIALES ENTRE ESTÍMULOS RELACIONADOS POR EQUIVALENCIA: UN ESTUDIO DE POTENCIALES CEREBRALES RELACIONADOS CON EVENTOS

    OpenAIRE

    ANGEL TABULLO; ALBERTO YORIO; SILVANO ZANUTTO; ALEJANDRO WAINSELBOIM

    2015-01-01

    La formación de clases de equivalencia entreestímulos ha sido propuesta en el campo del Aná-lisis Experimental del Comportamiento como unprerrequisito conductual para el lenguaje. Adi-cionalmente, existe evidencia de que la transfe-rencia de función entre estímulos equivalentespo dría explicar la adquisición de estructuras sin-tácticas simples. No obstante, la simplicidad delas funciones sintácticas estudiadas no capturó lacomplejidad combinatoria de la gramática natu-ral. Si la transferencia...

  13. Relación entre la creatividad y las funciones ejecutivas en alumnos de Educación Infantil. Propuesta de intervención.

    OpenAIRE

    Díaz-Rojas, Irene

    2014-01-01

    El objetivo de la presente investigación es proponer un programa de intervención neuropsicológico para desarrollar la creatividad en un grupo de 30 alumnos de Educación Infantil. Además se ha tratado de identificar si existe correlación entre el nivel de función ejecutiva (asociada a la corteza prefrontal) y el nivel de creatividad en la muestra estudiada. Para medir ambos constructos en la muestra analizada (con edades de 3 a 6 años) se empleó un cuestionario de creatividad y ...

  14. Représentations du rébétiko chez les élites intellectuelles de gauche entre la guerre civile et la dictature des colonels

    OpenAIRE

    Alexopoulos, Christina

    2016-01-01

    Les représentations du rébétiko chez les élites intellectuelles de gauche entre la guerre civile et la dictature sont ambivalentes. Si quelques voix minoritaires mettent en avant l’intérêt musical du genre, la plupart des intellectuels de gauche s’attardent sur ses thématiques pour stigmatiser son manque de combativité, son fatalisme, son apologie de la drogue et de la pornographie, signes selon elles d’une appartenance au lumpenprolétariat ou aux forces réactionnaires. Cette vision, dominant...

  15. Relación entre maltrato fetal, violencia y sintomatología depresiva durante el embarazo de mujeres adolescentes y adultas: Un estudio piloto

    OpenAIRE

    Galicia Moyeda, Iris Xóchitl; Universidad Nacional Autónoma de México; Martínez Sánchez, Brenda; Universidad Nacional Autónoma de México; Ordoñez Cervantes, Dulce María; Universidad Nacional Autónoma de México; Rosales Vega, Heizel Alida; Universidad Nacional Autónoma de México

    2013-01-01

    La adolescencia es una etapa vulnerable para algunas mujeres, pues se ha encontrado que sufren más depresión y violencia que las mujeres adultas, en especial si se encuentran encintas. Estas circunstancias pueden influir para que haya violencia hacia el producto. De ahí que el objetivo de este trabajo fue identificar la relación existente entre la violencia, la depresión y el maltrato fetal en 48 mujeres embarazadas adolescentes y adultas. Participaron mujeres que asistían a control prenatal ...

  16. Cerrando la brecha entre nativos e inmigrantes digitales a través de las competencias informáticas e informacionales

    OpenAIRE

    Ariel Sánchez Espinoza; Diana Castro Ricalde

    2013-01-01

    En este texto hacemos una reflexión acerca de las diferencias entre los llamados “nativos” e “inmigrantes digitales”, y aportamos datos que permiten identificar si un grupo tiene mayores ventajas sobre otro en relación con la enseñanza y el aprendizaje en esta era digital. Proponemos la adquisición y el desarrollo de competencias informáticas e informacionales en ambos grupos como estrategia para reducir la brecha digital “blanda” que priva en el sistema educativo e invitamos a resolver las i...

  17. A colisão entre a tutela dos direitos individuais e os valores fundamentais da sociedade na jurisprudência penal brasileira

    OpenAIRE

    Lopes, Erivan José da Silva

    2015-01-01

    No universo em franco desenvolvimento da dogmática dos direitos fundamentais, uma das evoluções mais produtivas diz respeito a sua dimensão objetiva, que atribui ao Estado um dever de proteção, não apenas sob o ponto de vista dos indivíduos, mas igualmente sob o ponto de vista da sociedade, já que se cuida de valores e fins que esta deve respeitar e concretizar. Por também possuírem natureza de normas principiológicas, as normas de direitos fundamentais, quando entram em colisão entre si, exi...

  18. Grado de Relación e Influencia entre el Desarrollo de Competencias Comunicativas de Alumnos de Tercero de Primaria y la Estrategia de Aprendizaje Basada en Proyectos

    OpenAIRE

    Hernández-Pérez, Dulce T.

    2012-01-01

    La investigación que a continuación se presenta se configura dentro del ámbito de estrategias de aprendizaje innovadoras, es descriptiva y está dirigida fundamentalmente a comprobar si existe grado de relación e influencia entre el desarrollo de competencias comunicativas en alumnos de tercer grado de educación primaria y la estrategia de aprendizaje basada en proyectos. El universo que ha abarcado la investigación es el circunscrito a alumnos y maestros de tercer grado de las escuelas...

  19. La abierta competencia entre el reconocimiento jurídico y la valoración social. El caso de la violencia de pareja

    OpenAIRE

    María Carolina Agoff

    2009-01-01

    Este artículo analiza el proceso de apropiación subjetiva de derechos de parte de las mujeres en el marco de las nuevas legislaciones que promueven la igualdad de género y el derecho a una vida libre de violencia en México. Si bien se observa una incipiente transformación de una cultura de las virtudes femeninas tradicionales en una cultura de derechos emancipatoria, existen aún muchos obstáculos para una tal apropiación. Se trata del conflicto entre normatividades, en particular, las normas ...

  20. El cuidado enfermero del vínculo y el apego entre padres y Madres e hijos prematuros en una unidad neonatal.

    OpenAIRE

    Serret Serret, María

    2014-01-01

    El nacimiento prematuro interrumpe un proceso de vinculación afectiva entre los padres y su hijo iniciado desde la concepción, e implica el ingreso del mismo en una UCIN. Ubicado en el nuevo paradigma de cuidado centrado en el desarrollo y la familia, el objetivo de esta tesis es analizar si las enfermeras dan respuesta a las necesidades de las madres y los padres para establecer una buena vinculación con sus hijos prematuros en una unidad neonatal. Es un estudio cualitativo, c...

  1. Análisis de los huracanes originados entre 1990 y 2011 en el Atlántico Norte y mar Caribe

    OpenAIRE

    Bou Parés, Elisenda

    2012-01-01

    Los objetivos de este trabajo son analizar los Huracanes más significativos habidos entre 1990 y 2011; aquellos digamos “curiosos” por la zona geográfica donde se han originado y los que han incluso llegado a las costas gallegas y europeas; averiguar por qué unos años son más intensos que otros; si tiene influencia el calentamiento global u otros factores (Niño/Niña…), en el aumento de la frecuencia e intensidad de los huracanes; qué nuevas tecnologías hay para su detección; hasta qué punto i...

  2. Pasiones políticas e imperialismo : la polémica entre Ginés de Sepúlveda y Bartolomé de las Casas

    OpenAIRE

    Chaparro, Sandra

    2001-01-01

    Durante siglos el «amor» se ha venido considerando una virtud política, sostenedora de la vida comunitaria y fuente de la solidaridad social. Como tal, se trata de una pasión que se encuentra en la base de los sistemas simbólicos del pensamiento político occidental, si bien hoy, pasiones y política parecen dos conceptos alejados entre sí No obstante, en un mundo en vías de globalización resurgen con fuerza términos como solidaridad o cooperación, conceptos ...

  3. Flujo de potencia entre estructuras complejas sometidas a excitaciones de alta frecuencia y aplicaciones a la detección de daño estructural

    OpenAIRE

    Torrealba Palacios, Manuel

    2009-01-01

    El tema central de investigación en esta Tesis es el estudio del comportamientodinámico de una estructura mediante modelos que describen la distribución deenergía entre los componentes de la misma y la aplicación de estos modelos parala detección de daños incipientes.Los ensayos dinámicos son un modo de extraer información sobre las propiedadesde una estructura. Si tenemos un modelo de la estructura se podría ajustar éstepara que, con determinado grado de precisión, tenga la misma respuesta q...

  4. Reliability study of ultra-thin gate oxides on strained-Si/SiGe MOS structures

    Energy Technology Data Exchange (ETDEWEB)

    Varzgar, John B. [School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle-upon-Tyne, Newcastle-upon-Tyne, NE1 7RU (United Kingdom)]. E-mail: j.b.varzgar@newcastle.ac.uk; Kanoun, Mehdi [School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle-upon-Tyne, Newcastle-upon-Tyne, NE1 7RU (United Kingdom); Uppal, Suresh [School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle-upon-Tyne, Newcastle-upon-Tyne, NE1 7RU (United Kingdom); Chattopadhyay, Sanatan [School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle-upon-Tyne, Newcastle-upon-Tyne, NE1 7RU (United Kingdom); Tsang, Yuk Lun [School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle-upon-Tyne, Newcastle-upon-Tyne, NE1 7RU (United Kingdom); Escobedo-Cousins, Enrique [School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle-upon-Tyne, Newcastle-upon-Tyne, NE1 7RU (United Kingdom); Olsen, Sarah H. [School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle-upon-Tyne, Newcastle-upon-Tyne, NE1 7RU (United Kingdom); O' Neill, Anthony [School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle-upon-Tyne, Newcastle-upon-Tyne, NE1 7RU (United Kingdom); Hellstroem, Per-Erik [KTH, Royal Institute of Technology, Department of Microelectronics and Information Technology, Electrum 229, SE-164 40 Kista (Sweden); Edholm, Jonas; Ostling, Mikael [KTH, Royal Institute of Technology, Department of Microelectronics and Information Technology, Electrum 229, SE-164 40 Kista (Sweden); Lyutovich, Klara; Oehme, Michael; Kasper, Erich [Institute of Semiconductor Engineering, University of Stuttgart, Pfaffenwaldring 47, Stuttgart D-70569 (Germany)

    2006-12-15

    The reliability of gate oxides on bulk Si and strained Si (s-Si) has been evaluated using constant voltage stressing (CVS) to investigate their breakdown characteristics. The s-Si architectures exhibit a shorter life time compared to that of bulk Si, which is attributed to higher bulk oxide charges (Q {sub ox}) and increased surface roughness in the s-Si structures. The gate oxide in the s-Si structure exhibits a hard breakdown (HBD) at 1.9 x 10{sup 4} s, whereas HBD is not observed in bulk Si up to a measurement period of 1.44 x 10{sup 5} s. The shorter lifetime of the s-Si gate oxide is attributed to a larger injected charge (Q {sub inj}) compared to Q {sub inj} in bulk Si. Current-voltage (I-V) measurements for bulk Si samples at different stress intervals show an increase in stress induced leakage current (SILC) of two orders in the low voltage regime from zero stress time to up to 5 x 10{sup 4} s. In contrast, superior performance enhancements in terms of drain current, maximum transconductance and effective channel mobility are observed in s-Si MOSFET devices compared to bulk Si. The results from this study indicate that further improvement in gate oxide reliability is needed to exploit the sustained performance enhancement of s-Si devices over bulk Si.

  5. Hierarchical Cd4SiS6/SiO2 Heterostructure Nanowire Arrays

    Directory of Open Access Journals (Sweden)

    Liu Jian

    2009-01-01

    Full Text Available Abstract Novel hierarchical Cd4SiS6/SiO2 based heterostructure nanowire arrays were fabricated on silicon substrates by a one-step thermal evaporation of CdS powder. The as-grown products were characterized using scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. Studies reveal that a typical hierarchical Cd4SiS6/SiO2 heterostructure nanowire is composed of a single crystalline Cd4SiS6 nanowire core sheathed with amorphous SiO2 sheath. Furthermore, secondary nanostructures of SiO2 nanowires are highly dense grown on the primary Cd4SiS6 core-SiO2 sheath nanowires and formed hierarchical Cd4SiS6/SiO2 based heterostructure nanowire arrays which stand vertically on silicon substrates. The possible growth mechanism of hierarchical Cd4SiS6/SiO2 heterostructure nanowire arrays is proposed. The optical properties of hierarchical Cd4SiS6/SiO2 heterostructure nanowire arrays are investigated using Raman and Photoluminescence spectroscopy.

  6. Modification of eutectic Si in Al–Si alloys with Eu addition

    International Nuclear Information System (INIS)

    Al–5 wt.% Si-based alloys with 0.05 wt.% Eu addition were produced by controlled sand-casting and melt-spinning, respectively. The modification of eutectic Si caused by 0.05 wt.% Eu addition was investigated by thermal analysis, differential scanning calorimetry and multi-scale microstructure characterization techniques. In the case of controlled sand-casting, 0.05 wt.% Eu addition was found to modify the eutectic Si into a fibrous morphology. Multiply twinned Si particles were observed within eutectic Si. Furthermore, the Al2Si2Eu phase was also observed both in the vicinity of eutectic Si and within eutectic Si, which was believed to hinder Si growth. In the case of melt-spun samples, nanometer-sized Al2Si2Eu phases were observed. However, after controlled cooling in a differential scanning calorimeter, multiply twinned Si particles were observed. The formation of multiply twinned Si particles was attributed to the adsorption of Eu atoms along the 〈1 1 2〉Si growth direction of Si and at the intersection of two {1 1 1}Si facets. Twinning was observed in both fundamentally different casting processes: controlled sand-casting and melt-spinning. This is fully consistent with the well-known poisoning of the twin plane re-entrant edge and the impurity-induced twinning modification mechanisms

  7. Comportamento de violência e fatores associados entre estudantes de Barra do Garças, MT

    Directory of Open Access Journals (Sweden)

    Marta de Lima Castro

    2011-12-01

    Full Text Available OBJETIVO: Estimar a prevalência de violência entre adolescentes e jovens adultos e identificar fatores associados. MÉTODOS: Estudo transversal com amostragem aleatória sistemática de 699 estudantes do ensino fundamental e médio da rede pública urbana de Barra do Garças, MT, em 2008. Questionário autopreenchível foi aplicado em sala de aula sem a presença do professor. O desfecho "comportamento violento" foi definido como (1 uso de arma de fogo ou branca, e/ou (2 agressões contra si e ou terceiros, e/ou (3 tentativa de suicídio. As variáveis independentes analisadas foram idade, gênero, condição socioeconômica, uso de álcool, uso de drogas psicoativas, atividade sexual e relacionamento com os pais. Foram realizadas análises univariadas e regressão múltipla ajustada para efeito de agregado. RESULTADOS: A prevalência de violência foi de 18,6%, variando segundo a idade: de 10,1% no grupo de dez e 11 anos; 20,2% dos 12 aos 19 anos; e 4,5% dos 20 e 21 anos. Os fatores associados ao comportamento de violência foram uso de álcool (RP = 2,51, IC95% 1,22;5,15, uso de drogas psicoativas (RP = 2,10, IC95%1,61;2,75, gênero masculino (RP = 1,63, IC95% 1,13;2,35 e relações insatisfatórias entre os pais (RP = 1,64, IC95% 1,25;2,15. CONCLUSÕES: Os resultados indicam alta prevalência de violência entre os adolescentes na faixa etária de 12 a 19 anos, sobretudo entre os usuários de álcool e drogas, do sexo masculino, de família cujos pais não possuem relações satisfatórias. Embora sem significância estatística no modelo final de regressão, a defasagem escolar e nível socioeconômico devem ser considerados em ações educativas de prevenção ao comportamento de violência entre estudantes.

  8. Comparison of the thermal stabilities of NiSi films in Ni/Si, Ni/Pd/Si and Ni/Pt/Si systems

    CERN Document Server

    Wang, R N

    2003-01-01

    The effects of different interlayer materials (Pd and Pt) deposited between Ni films and Si substrates on the NiSi thermal stability are discussed. Ni sub 0 sub . sub 9 sub 4 sub 3 Pd sub 0 sub . sub 0 sub 5 sub 7 Si and Ni sub 0 sub . sub 9 sub 4 sub 5 Pt sub 0 sub . sub 0 sub 5 sub 5 Si solid solutions were formed when the samples were annealed at high temperatures and the lattice parameters of Ni sub 0 sub . sub 9 sub 4 sub 3 Pd sub 0 sub . sub 0 sub 5 sub 7 Si were calculated according to Vegard's law. The NiSi thermal stability was enhanced by interposing a Pd or Pt interlayer, and the sample with the Pt interlayer had the highest NiSi thermal stability among all the samples studied. This is attributed to the reduction of the interface energy between NiSi and Si substrates and the decrease of the driving force for the nucleation of NiSi sub 2 , induced by formation of the NiSi(200) preferred orientation and the solid solution respectively.

  9. Theoretic Study on Band Structure of Si/SiNx Multilayer Film%Si/SiNx多层膜能带结构的理论研究

    Institute of Scientific and Technical Information of China (English)

    徐明; 魏屹; 何贤模; 芦伟

    2010-01-01

    利用Kronig-Penney模型计算了Si/SiNx多层膜结构中Si亚层的能带结构.结果表明,无论是减少Si或Si/SiNx亚层的厚度都将导致Si层的带隙发生宽化,计算结果与实验值符合较好.进而还发现,当Si层厚度减小时,Si/SiNx多层膜结构中载流子(电子和空穴)的有效质量均减小,有利于对载流子复合发光的控制.计算结果对实验上研究发光可控的Si/SiNx多层膜结构有重要指导意义.

  10. Differential cross sections measurement of 28Si(p,p/γ)28Si and 29Si(p,p/γ)29Si reactions for PIGE applications

    Science.gov (United States)

    Jokar, A.; Kakuee, O.; Lamehi-Rachti, M.

    2016-03-01

    Differential cross sections for gamma-ray emission from the 28Si(p,p/γ)28Si (Eγ = 1779 keV) and the 29Si(p,p/γ)29Si (Eγ = 1273 keV) nuclear reactions were measured in the energy range of 2.0-3.2 MeV and 2.0-3.0 MeV, respectively. The thin Si targets were prepared by evaporating natural SiO onto self-supporting Ag films. The gamma-rays and backscattered protons were detected simultaneously. An HPGe detector placed at an angle of 90° with respect to beam direction was employed to collect gamma-rays while an ion implanted Si detector placed at a scattering angle of 165° was used to detect backscattered protons. The great advantage of this work is that differential cross sections were obtained with a procedure irrespective of absolute value of the collected beam charge.

  11. Deformation effects in the 28Si + 12C and 28Si + 28Si reactions

    Indian Academy of Sciences (India)

    C Bhattacharya; M Rousseau; C Beck; V Rauch; R M Freeman; R Nouicer; F Haas; O Dorvaux; K Eddahbi; P Papka; O Stezwski; S Szilner; D Mahboub; A Szanto De Toledo; A Hachem; E Martin; S J Sanders

    2001-07-01

    The possible occurrence of highly deformed configurations is investigated in the 40Ca and 56Ni di-nuclear systems as formed in the 28Si + 12C, 28Si reactions by using the properties of emitted light charged particles. Inclusive as well as exclusive data of the heavy fragments and their associated light charged particles have been collected by using the ICARE charged particle multidetector array. The data are analysed by Monte Carlo CASCADE statistical-model calculations using a consistent set of parameters with spin-dependent level densities. Significant deformation effects at high spin are observed as well as an unexpected large 8Be cluster emission of a binary nature.

  12. Corrosion properties of amorphous Mo-Si-N and nanolayered Mo-Si-Nn/SiC coatings

    Energy Technology Data Exchange (ETDEWEB)

    Torri, P.; Mahiout, A.; Koskinen, J.; Hirvonen, J.P.; Johansson, L.S.

    2000-02-01

    Corrosion properties of sputter deposited MoSi{sub 2}, SiC, Mo-Si-N (MoSi{sub 2.2}N{sub 2.5}) and nanolayered Mo-Si-N/SiC coatings on Fe37 low carbon steel have been studied using electrochemical polarization measurements in 1 N H{sub 2}SO{sub 4} solution. A decrease in both critical current density for passivation and minimum current in passive state was observed in annealed nanolayered Mo-Si-N/SiC coating compared to each of its constituents alone as single layer coating. On contrary to MoSi{sub 2} coating, only slight increase in critical current density was observed in Mo-Si-N coated sample after annealing. Molybdenum disilicide source material has good thermal and electrical conductivity, which allows effective dc-magnetron sputter deposition. Therefore this is a relatively simple method to produce amorphous coatings which have a high crystallization temperature and promising properties for corrosion applications.

  13. Fiber/matrix interfaces for SiC/SiC composites: Multilayer SiC coatings

    Energy Technology Data Exchange (ETDEWEB)

    Halverson, H.; Curtin, W.A. [Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States)

    1996-08-01

    Tensile tests have been performed on composites of CVI SiC matrix reinforced with 2-d Nicalon fiber cloth, with either pyrolitic carbon or multilayer CVD SiC coatings [Hypertherm High-Temperature Composites Inc., Huntington Beach, CA.] on the fibers. To investigate the role played by the different interfaces, several types of measurements are made on each sample: (i) unload-reload hysteresis loops, and (ii) acoustic emission. The pyrolitic carbon and multilayer SiC coated materials are remarkably similar in overall mechanical responses. These results demonstrate that low-modulus, or compliant, interface coatings are not necessary for good composite performance, and that complex, hierarchical coating structures may possibly yield enhanced high-temperature performance. Analysis of the unload/reload hysteresis loops also indicates that the usual {open_quotes}proportional limit{close_quotes} stress is actually slightly below the stress at which the 0{degrees} load-bearing fibers/matrix interfaces slide and are exposed to atmosphere.

  14. A interface entre Saúde Pública e Cibercultura

    OpenAIRE

    Eduardo Jorge Sant Ana Honorato

    2014-01-01

    Este artigo, de caráter opinativo, propõe uma reflexão sobre como está a relação entre a cibercultura e a saúde pública e sua utilização como meio de pesquisa, e não apenas como instrumento. Cibercultura seria então uma nova forma de relação entre sujeitos. É justamente "através" e "pelas" relações sociais que os indivíduos adquirem habilidades técnicas e comunicação. Mudam-se as formas relacionais, os meios, mas os fins permanecem os mesmos: o de estarem em contato com outros humanos. Nas úl...

  15. A ética da palavra entre os Wapishana

    Directory of Open Access Journals (Sweden)

    Farage Nádia

    1998-01-01

    Full Text Available O artigo explora princípios éticos que fundamentam a codificação retórica dos Wapishana, povo de filiação lingüística Maipura/Arawak, habitante no interflúvio Branco/Rupununi, fronteira entre Brasil e República da Guiana. Nesta codificação, uma equação necessária se estabelece entre linguagem e alma, vinculando o uso decoroso daquela - o diálogo, por excelência - à sociabilidade humana. Por esta via, o artigo busca circunscrever a concepção que sustentam os Wapishana quanto à condição humana.

  16. Simulation analysis of the effects of a back surface field on a p-a-Si:H/n-c-Si/n+-a-Si:H heterojunction solar cell

    Institute of Scientific and Technical Information of China (English)

    Hu Yuehui; Zhang Xiangwen; Qu Minghao; Wang Lifu; Zeng Tao; Xie Yaojiang

    2009-01-01

    In order to investigate the effects of a back surface field (BSF) on the performance of a p-doped amorphous silicon (p-a-Si:H)/n-doped crystalline silicon (n-c-Si) solar cell, a heterojunction solar cell with a p-a-Si:H/nc-Si/n+-a-Si:H structure was designed. An n+-a-Si:H film was deposited on the back of an n-c-Si wafer as the BSF.The photovoltaic performance of p-a-Si:H/n-c-Si/n+-a-Si:H solar cells were simulated. It was shown that the BSF of the p-a-Si:H/n-c-Si/n+-a-Si:H solar cells could effectively inhibit the decrease of the cell performance caused by interface states.

  17. Les Affinités électives de Goethe : entre science et littérature

    Directory of Open Access Journals (Sweden)

    Bernard Joly

    2011-03-01

    Full Text Available Par leur titre même, Les affinités électives de Goethe renvoient à la doctrine chimique des rapports entre différents corps qui, à partir des travaux d’Etienne-François Geoffroy en 1718, s’impose comme théorie dominante dans la chimie du XVIIIe siècle. Goethe ne se contente pas d’une simple analogie entre les attirances amoureuses qui font et défont les couples et les opérations chimiques qui règlent les liaisons et les précipitations des substances chimiques. Son excellente connaissance de la tradition chimique et alchimique le conduit à considérer l’affinité comme une loi de la nature produisant aussi bien ses effets en chimie que chez les êtres vivants et dans le psychisme.The title of Goethe’s novel Elective Affinities refer to the chemical tenet of rapports between different bodies which, from Etienne-François Geoffroy’s works in 1718, emerge as a prevailing theory in the eighteenth-century chemistry. Goethe does not limit his views to the analogy between love attractions which made and break up couples and chimical processes which determine bonds and precipitations of chemical substances. His excellent knowledge of chemical and alchemical tradition leads him to consider affinity as a law of nature having effects in chemistry as well as in living being and into mind.

  18. El discurso de la transformación de la universidad, entre la universalidad y la particularidad

    Directory of Open Access Journals (Sweden)

    Ana Leticia Tamayo Salcedo

    2009-01-01

    Full Text Available En el marco de los procesos de la globalización mundial, la demanda y el desafío que se le ha planteado a las universidades ha sido la de su reforma y transformación. Esta necesidad de transformación se ha ubicado en lo relativo a los aspectos curriculares y administrativos, que se plantean en el marco de las políticas educativas, a través del gobierno federal y las recomendaciones emitidas por los organismos internacionales, como el Banco Mundial, presentándose como el ideal de plenitud (la universalidad, es decir, como una propuesta hegemónica. El encuentro entre lo global y lo nacional o local -entiéndase, lo universal y lo particular respectivamente-, no está determinado a priori, si bien las recomendaciones emitidas por los organismos internacionales han operado como lineamientos de las políticas educativas mexicanas, no se puede hablar de una reproducción exacta, sino de su resignificación y adaptación en los contextos particulares dentro de los que pretende implementarse. Así la transformación de la universidad se constituye en un espacio de lucha y negociación constante, en donde se tejen articulaciones y antagonismos entre actores y discursos, en la disputa por la orientación que debe seguir la transformación de la educación superior.

  19. Medidas de desempeño competitivo entre empresas con diferente estructura de la propiedad del capital

    Directory of Open Access Journals (Sweden)

    Josefina Fernández-Guadaño

    2013-01-01

    Full Text Available Este trabajo analiza la evolución del comportamiento económico comparado entre las empresas propiedad de sus trabajadores y las empresas capitalistas convencionales, con la finalidad, en función de los resultados, de potenciar el reconocimiento legal europeo del modelo de sociedad limitada laboral. Se trata de un estudio de corte exploratorio, la metodología utilizada para estudiar si existen diferencias entre los dos tipos de empresas ha sido la realización de pruebas paramétricas. Los resultados del análisis no evidencian de forma empírica los efectos positivos que se presuponían a las empresas propiedad de sus trabajadores, no siendo determinantes, por tanto, para hacer una recomendación regulatoria a nivel europeo, aunque encontrándose motivos suficientes para ampliar el estudio al análisis comparado de otros sujetos con regulación legal propia e, incluso, al análisis comparado de otras formas regulatorias existentes en otros Estados Miembros de la Unión Europea.

  20. Resistência de união entre liga de níquel-cromo e cimentos resinosos

    Directory of Open Access Journals (Sweden)

    FRANÇA Rodrigo de Oliveira

    1998-01-01

    Full Text Available O objetivo do trabalho foi a determinação da retentividade, por ensaio de tração, entre uma liga de níquel-cromo e cimentos resinosos (Comspan, Panavia Ex e All-Bond C & B, com quatro tratamentos superficiais (liso, microjateado, ataque eletrolítico e silicoater e armazenagem por 3 e 30 dias em solução de NaCl a 0,9%, a 37° C e termociclagem intercalada na segunda (a 5 e 55° C, por 1 minuto em cada banho, perfazendo 600 ciclos. Os corpos de prova eram discos, providos de alça fixadora entre si dois a dois. Os resultados permitiram concluir que: superfícies lisas conduzem a baixíssimas retentividades e tratadas com silicoater a altíssimos valores, com qualquer cimento e condição de armazenagem; Panavia Ex com superfícies microjateadas também conduz a altas retentividades; a maior retentividade foi obtida pela combinação silicoater/All-Bond C&B.

  1. Si3N4/SiC nanocomposite powder from a preceramic polymeric network based on poly(methylsilane as the SiC precursor

    Directory of Open Access Journals (Sweden)

    Gozzi Maurício F.

    2001-01-01

    Full Text Available Si3N4/SiC nanocomposite powders were obtained from a preceramic polymeric network based on poly(methylsilane as the in situ quasi-stoichiometric SiC source. These powders were constituted of nanosized SiC particles homogeneously distributed in the Si3N4 particulate matrix. beta-SiC whiskers were grown at 1400 °C in the pores of the matrix. At 1600 °C, the alpha -> beta Si3N4 phase transition took place, but no elemental silicon from Si3N4 decomposition was detected, evidencing the protective effect of the SiC phase.

  2. Fabrication and characterization of Ti3SiC2–SiC nanocomposite by in situ reaction synthesis of TiC/Si/Al powders

    Indian Academy of Sciences (India)

    Baoyan Liang; Mingzhi Wang; Xiaopu Li; Yunchao Mu

    2011-12-01

    The microstructure and mechanical properties of Ti3SiC2–SiC nanocomposite fabricated by in situ hot pressing (HP) synthesis process were studied. The results show that dense Ti3SiC2–SiC composite contained minor TiSi2 obtained by hot sintering at 1350°C for 1 h. The average grain size of Ti3SiC2 was 4 m in length, and the size of SiC grains is about 100 nm. With its fine microstructure, the Ti3SiC2–SiC nanocomposite shows good mechanical properties.

  3. Surface modifying of SiC particles and performance analysis of SiCp/Cu composites

    Science.gov (United States)

    Ming, Hu; Yunlong, Zhang; Lili, Tang; Lin, Shan; Jing, Gao; Peiling, Ding

    2015-03-01

    In this study, the electroless copper plating method was applied to deposit a Cu coating on SiCp in order to improve interface bonding performance. The SiCp surface morphology with uncoated and coated copper was investigated. The SiCp/Cu composite was fabricated by the hot-pressed sintering technology. SiC particles with various contents were used as reinforcement. The results showed that the distribution of reinforced particle with electroless plating copper coating was uniform in the copper matrix. The SiCp content played had an important role on thermal expansion coefficient and wear properties behaviors of the SiCp/Cu composites. The wear resistance capacity and thermal expansion coefficient of the composites decreased with increasing amount of SiC. Compared with the pure Cu matrix, the obtained SiCp/Cu composites had better capacity of the wear resistance. The SiCp/Cu composites increased when compared with the pure Cu material.

  4. Fusion of Si28+Si28,30: Different trends at sub-barrier energies

    Science.gov (United States)

    Montagnoli, G.; Stefanini, A. M.; Esbensen, H.; Jiang, C. L.; Corradi, L.; Courtin, S.; Fioretto, E.; Grebosz, J.; Haas, F.; Jia, H. M.; Mazzocco, M.; Michelagnoli, C.; Mijatović, T.; Montanari, D.; Parascandolo, C.; Scarlassara, F.; Strano, E.; Szilner, S.; Torresi, D.

    2014-10-01

    Background: The fusion excitation function of the system Si28+Si28 at energies near and below the Coulomb barrier is known only down to ≃15 mb. This precludes any information on both coupling effects on sub-barrier cross sections and the possible appearance of hindrance. For Si28+Si30 even if the fusion cross section is measured down to ≃50 μb, the evidence of hindrance is marginal. Both systems have positive fusion Q values. While Si28 has a deformed oblate shape, Si30 is spherical. Purpose: We investigate 1. the possible influence of the different structure of the two Si isotopes on the fusion excitation functions in the deep sub-barrier region and 2. whether hindrance exists in the Si+Si systems and whether it is strong enough to generate an S-factor maximum, thus allowing a comparison with lighter heavy-ion systems of astrophysical interest. Methods: Si28 beams from the XTU Tandem accelerator of the INFN Laboratori Nazionali di Legnaro were used. The setup was based on an electrostatic beam separator, and fusion evaporation residues (ER) were detected at very forward angles. Angular distributions of ER were measured. Results: Fusion cross sections of Si28+Si28 have been obtained down to ≃600 nb. The slope of the excitation function has a clear irregularity below the barrier, but no indication of a S-factor maximum is found. For Si28+Si30 the previous data have been confirmed and two smaller cross sections have been measured down to ≃4 μb. The trend of the S-factor reinforces the previous weak evidence of hindrance. Conclusions: The sub-barrier cross sections for Si28+Si28 are overestimated by coupled-channels calculations based on a standard Woods-Saxon potential, except for the lowest energies. Calculations using the M3Y+repulsion potential are adjusted to fit the Si28+Si28 and the existing Si30+Si30 data. An additional weak imaginary potential (probably simulating the effect of the oblate Si28 deformation) is required to fit the low-energy trend of

  5. Propagation of misfit dislocations from buffer/Si interface into Si

    Science.gov (United States)

    Liliental-Weber, Zuzanna; Maltez, Rogerio Luis; Morkoc, Hadis; Xie, Jinqiao

    2011-08-30

    Misfit dislocations are redirected from the buffer/Si interface and propagated to the Si substrate due to the formation of bubbles in the substrate. The buffer layer growth process is generally a thermal process that also accomplishes annealing of the Si substrate so that bubbles of the implanted ion species are formed in the Si at an appropriate distance from the buffer/Si interface so that the bubbles will not migrate to the Si surface during annealing, but are close enough to the interface so that a strain field around the bubbles will be sensed by dislocations at the buffer/Si interface and dislocations are attracted by the strain field caused by the bubbles and move into the Si substrate instead of into the buffer epi-layer. Fabrication of improved integrated devices based on GaN and Si, such as continuous wave (CW) lasers and light emitting diodes, at reduced cost is thereby enabled.

  6. Study of indentation induced cracks in MoSi2-reaction bonded SiC ceramics

    Indian Academy of Sciences (India)

    O P Chakrabarti; P K Das; S Mondal

    2001-04-01

    MoSi2–RBSC composite samples were prepared by infiltration of Si–2 at.% Mo melt into a preform of commercial SiC and petroleum coke powder. The infiltrated sample had a density > 92% of the theoretical density (TD) and microstructurally contained SiC, MoSi2, residual Si and unreacted C. The material was tested for indentation fracture toughness at room temperature with a Vicker’s indenter and KIC was found to be 4.42 MPa√m which is around 39% higher than the conventional RBSC material. Enhancement in indentation fracture toughness is explained in terms of bowing of propagating cracks through MoSi2/SiC interface which is under high thermal stress arising from the thermal expansion mismatch between MoSi2 and SiC.

  7. High-performance a -Si/c-Si heterojunction photoelectrodes for photoelectrochemical oxygen and hydrogen evolution

    KAUST Repository

    Wang, Hsin Ping

    2015-05-13

    Amorphous Si (a-Si)/crystalline Si (c-Si) heterojunction (SiHJ) can serve as highly efficient and robust photoelectrodes for solar fuel generation. Low carrier recombination in the photoelectrodes leads to high photocurrents and photovoltages. The SiHJ was designed and fabricated into both photoanode and photocathode with high oxygen and hydrogen evolution efficiency, respectively, by simply coating of a thin layer of catalytic materials. The SiHJ photoanode with sol-gel NiOx as the catalyst shows a current density of 21.48 mA/cm2 at the equilibrium water oxidation potential. The SiHJ photocathode with 2 nm sputter-coated Pt catalyst displays excellent hydrogen evolution performance with an onset potential of 0.640 V and a solar to hydrogen conversion efficiency of 13.26%, which is the highest ever reported for Si-based photocathodes. © 2015 American Chemical Society.

  8. Microwave Annealing for NiSiGe Schottky Junction on SiGe P-Channel

    Directory of Open Access Journals (Sweden)

    Yu-Hsien Lin

    2015-11-01

    Full Text Available In this paper, we demonstrated the shallow NiSiGe Schottky junction on the SiGe P-channel by using low-temperature microwave annealing. The NiSiGe/n-Si Schottky junction was formed for the Si-capped/SiGe multi-layer structure on an n-Si substrate (Si/Si0.57Ge0.43/Si through microwave annealing (MWA ranging from 200 to 470 °C for 150 s in N2 ambient. MWA has the advantage of being diffusion-less during activation, having a low-temperature process, have a lower junction leakage current, and having low sheet resistance (Rs and contact resistivity. In our study, a 20 nm NiSiGe Schottky junction was formed by TEM and XRD analysis at MWA 390 °C. The NiSiGe/n-Si Schottky junction exhibits the highest forward/reverse current (ION/IOFF ratio of ~3 × 105. The low temperature MWA is a very promising thermal process technology for NiSiGe Schottky junction manufacturing.

  9. Factores socioculturales y consumo de drogas entre estudiantes universitarios costarricenses

    Directory of Open Access Journals (Sweden)

    Jaime Alonso Caravaca Morera

    2015-01-01

    Full Text Available Investigación cuantitativa de tipo descriptiva-exploratoria, con diseño transversal que examinó el efecto moderador de ciertos factores socio-culturales en el consumo de drogas entre estudiantes universitarios en San José, Costa Rica. La muestra fue conformada por 126 mujeres y 124 hombres de una universidad pública de forma no probabilística. Fue elaborado un cuestionario con cinco escalas ya validadas, que interrogaba sobre la influencia del grupo de pares, las relaciones familiares, el entretenimiento, la espiritualidad y el consumo de drogas. Se utilizó el programa SPSS versión 18 para el análisis estadístico. Se estableció que el 98,4% de los estudiantes reportaron tener por lo menos un amigo que consumía drogas, las drogas más consumidas fueron alcohol, tabaco y marihuana. Se estableció asociación significativa entre algunos factores académicos y culturales con el consumo de drogas legales e ilegales. Se concluye que deben ser implementadas estrategias preventivas considerando la influencia de los factores culturales entre los estudiantes universitarios.

  10. Maltrato entre iguales e intento suicida en sujetos adolescentes escolarizados

    Directory of Open Access Journals (Sweden)

    Isabel Valadez

    2011-01-01

    Full Text Available Objetivo: Conocer la relación entre el maltrato entre iguales y el intento suicida en sujetos adolescentes escolarizados. Método: Aplicación a 723 sujetos adolescentes escolarizados de un cuestionario que incluye escalas Likert que evalúan dificultades escolares (desempeño escolar y maltrato, ideas y pensamientos suicidas, sentimientos de soledad y de abandono, aislamiento, y antecedente de intento suicida. Para estimar la fuerza de asociación entre las dificultades escolares con las variables estudiadas utilizamos el estadístico OR (odds ratio en inglés y razón de momios en español. Consideramos que existe asociación cuando el OR es superior a uno. Resultados: Las dificultades escolares se asociaron con significancia estadística a las variables estudiadas. Conclusiones: Las experiencias de victimización ponen al sujeto adolescente en mayor situación de riesgo de sufrir desajustes psicosociales.

  11. Proyectos educativos: estudio comparativo entre Venezuela y Colombia

    Directory of Open Access Journals (Sweden)

    Mineira Finol

    2005-09-01

    Full Text Available El Proyecto Educativo Integral Comunitario (PEIC y el Proyecto Educativo Institucional constituyen la categoría de comparación entre Venezuela y Colombia; a tal fin, este estudio de tipo comparativo-documental se centró en determinar congruencias y discrepancias entre PEIC y PEI, utilizando el método comparativo estructurado en cuatro fases: descripción, interpretación, yuxtaposición y comparación, propuesto por Hilker y Bereday (1972 Entre los resultados se tienen: congruencias en cuanto surgen sobre las bases de diagnóstico externos efectuados por organismos internacionales UNESCO, CEPAL ante la inefectividad y baja productividad de ambos países; a nivel interno responden a políticas educativas reformadoras de currículum y leyes,. Discrepancias referidas al tiempo de implementación; en Venezuela a partir de 1996; Colombia en 1992; este último, consolidó las bases para la participación a través del gobierno escolar y de un sistema de evaluación institucional, muy incipiente en Venezuela.

  12. Relaciones de equivalencia: competitividad entre la historia preexperimental y experimental

    Directory of Open Access Journals (Sweden)

    José Luis Ybarra Sagarduy

    2002-01-01

    Full Text Available Diversos estudios han mostrado la dificultad en establecer nuevas relaciones entre estímulos debido a la historia preexperimental o bien a la inducida experimentalmente. Eikeseth y Baer (1997 observaron este efecto al tratar de entrenar relaciones de equivalencia entre estímulos (letras del alfabeto que presentaban una relación de orden en un único sentido (® por la historia preexperimental. El presente trabajo tiene como objetivo estudiar este efecto en nuevos estímulos que presentan relaciones de orden en ambos sentidos (« por historia preexperimental (números o relaciones en un único sentido (® pero por historia inducida (versos de un poema. Se expuso a doce niños al entrenamiento en relaciones de equivalencia con tres condiciones experimentales (letras, números y versos de un poema y una control (símbolos griegos aplicadas a nivel intrasujeto. En las condiciones experimentales los ensayos de prueba de equivalencia se dividían entre aquellos donde competían la historia preexperimental o la inducida y la de entrenamiento, y aquellos donde no se producía tal competitividad, con el fin de observar el predominio de una historia u otra. Los resultados indicaron un predominio de la historia preexperimental o la inducida sobre la de entrenamiento en las tres condiciones experimentales. Se discuten las implicaciones de los resultados en el ámbito clínico.

  13. Amistad entre machos adultos de monos aulladores negros y dorados

    Directory of Open Access Journals (Sweden)

    Kowalewski, Martín M.

    2007-01-01

    Full Text Available El éxito reproductivo de los machos depende fundamentalmente del número de hembras que puedan fertilizar. Por lo tanto, los machos deberían competir activamente por las fertilizaciones. Sin embargo, en muchas especies de primates no-humanos, los machos conviven pacíficamente en grupos sociales. En este estudio exploramos las relaciones afiliativas entre machos de Alouatta caraya en la Isla Brasilera (27º 20’ S-58º 40’ W en el Noreste argentino. Dos grupos multimacho fueron estudiados durante 5 días por mes durante el año 2004. Definimos amistad como las interacciones afiliativas en díadas incluyendo proximidad, tolerancia durante la alimentación, interacciones de acicalamiento, y soporte en coaliciones. Por ejemplo, encontramos que los índices de asociación entre individuos basados en distancias y acicalamiento, difieren significativamente de lo esperado por azar a lo largo del año y en diferentes contextos comportamentales (p<0.05. Esto sugiere la existencia de pares de machos que se asociaron con mayor frecuencia que lo esperado por azar en ambos grupos. La existencia de afinidad social entre machos emparentados y no emparentados nos presenta nuevas preguntas en el estudio de la evolución de la amistad en primates no-humanos. Este tipo de estudios permite modelar nuevas ideas acerca de la historia evolutiva de la amistad en humanos.

  14. Evaluation of photovoltaic properties of nanocrystalline-FeSi2/Si heterojunctions

    Science.gov (United States)

    Shaban, Mahmoud; Bayoumi, Amr M.; Farouk, Doaa; Saleh, Mohamed B.; Yoshitake, Tsuyoshi

    2016-09-01

    In this paper, an application of nanocrystalline iron disilicide (NC-FeSi2) combined with nanocrystalline-Si (NC-Si) in a heterostructured solar cell is introduced and numerically evaluated in detail. The proposed cell structure is studied based on an experimental investigation of photovoltaic properties of NC-FeSi2/crystalline-Si heterojunctions, composed of unintentionally-doped NC-FeSi2 thin film grown on Si substrate. Photoresponse measurement of NC-FeSi2/crystalline-Si heterojunction confirmed ability of NC-FeSi2 to absorb NIR light and to generate photocarriers. However, collection of these carriers was not so efficient and a radical improvement in design of the device is required. Therefore, a modified device structure, comprising of NC-FeSi2 layer sandwiched between two heavily-doped p- and n-type NC-Si, is suggested and numerically evaluated. Simulation results showed that the proposed structure would exhibit a relatively high conversion efficiency of 25%, due to an improvement in collection efficiency of photogenerated carriers in the NC-FeSi2 and NC-Si layers. To attain such efficiency, defect densities in NC-FeSi2 and NC-Si layers should be kept less than 1014 and 1016 cm-3 eV-1, respectively. Remarkable optical and electrical properties of NC-FeSi2, employed in the proposed structure, facilitate improving device quantum efficiency spectrum providing significant spectrum extension into the near-infrared region beyond Si bandgap.

  15. In-Plane Si Nanowire Growth Mechanism in Absence of External Si Flux.

    Science.gov (United States)

    Curiotto, Stefano; Leroy, Frédéric; Cheynis, Fabien; Müller, Pierre

    2015-07-01

    We report on a new mechanism of nanowire formation: during Au deposition on Si(110) substrates, Au-Si droplets grow, move spontaneously, and fabricate a Si nanowire behind them in the absence of Si external flux. Nanowires are formed by Si dissolved from the substrate at the advancing front of the droplets and transported backward to the crystallization front. The droplet shape is determined by the Si etching anisotropy. The nanowire formation can be tuned by changing experimental parameters like substrate temperature and Au deposition rate.

  16. Si/SiO2/p-Si结构的电学特性

    Institute of Scientific and Technical Information of China (English)

    马自军; 马书懿

    2008-01-01

    用射频磁控溅射法在p-Si衬底上制备了Si/SiO2薄膜,利用Au/(Si/SiO2)/p-Si结构的I-V特性曲线对其电学特性进行了分析.结果表明,样品具有很好的整流作用,起整流作用的势垒存在于(Si/SiO2)/p-Si界面附近.

  17. Hydrogen Passivation Effect on Enhanced Luminescence from Nanocrystalline Si/SiO2 Multilayers

    Institute of Scientific and Technical Information of China (English)

    XIA Zheng-Yue; HAN Pei-Gao; XU Jun; CHEN De-Yuan; WEI De-Yuan; MA Zhong-Yuan; CHEN Kun-Ji; XU Ling; HUANG Xin-Fan

    2007-01-01

    Nanocrystalline Si/SiO2 multilayers are prepared by thermally annealing amorphous Si/SiO2 stacked structures.The photoluminescence intensity is obviously enhanced after hydrogen passivation at various temperatures. It is suggested that the hydrogen trapping and detrapping processes at different temperatures strongly influence the passivation effect. Direct experimental evidence is given by electron spin resonance spectra that hydrogen effectively reduces the nonradiative defect states existing in the Si nanocrystas/SiO2 system which enhances the radiative recombination probability. The luminescence characteristic shows its stability after hydrogen passivation even after aging eight months.

  18. Excitation wavelength dependent photoluminescence in structurally non-uniform Si/SiGe-island heteroepitxial multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Modi, N.; Tsybeskov, L. [Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102 (United States); Lockwood, D. J.; Wu, X.; Baribeau, J.-M. [Institute for Microstructural Sciences, National Research Council, Ottawa, Ontario K1A 0R6 (Canada)

    2012-06-01

    In nanometer-size Si/SiGe-island heteroepitxial multilayers grown on Si(001), low temperature photoluminescence spectra are observed that strongly depend on the excitation wavelength and show a strong correlation with structural properties revealed by transmission electron microscopy. These experimental results can be explained by assuming that the optically created carriers are strongly localized at Si/SiGe island heterointerfaces. We show that electron-hole pairs are generated and recombine within spatial regions mainly defined by the photoexcitation penetration depth, and that the estimated exciton diffusion length is notably short and comparable with the SiGe-island average size.

  19. High temperature oxidation of SiC under helium with low-pressure oxygen. Part 3: β-SiC-SiC/PyC/SiC

    International Nuclear Information System (INIS)

    In the frame of generation IV gas-cooled fast reactor (GFR), the cladding materials currently considered is a SiC/SiC-based composite with a pyrocarbon interphase and a β-SiC coating on the surface to close the porosity (noted beta-SiC-SiC/PyC/SiC). These elements are subjected to temperatures going from 1300 to 1500 K in nominal operating conditions to 1900-2300 K in accidental conditions. The coolant gas considered is helium pressurized at 7 MPa. After a thermodynamic study carried out on the oxidation of beta-SiC under helium and low oxygen partial pressures, an experimental approach was made on β-SiC-SiC/PyC/SiC composites under active oxidation conditions (1400 ≤ T ≤ 2300 K; 0.2 ≤ pO2 ≤ 2 Pa). This study follows two preceding studies carried out on two polytypes of SiC: α (Part 1) and β (Part 2) under the same conditions. In these studies, the influence of the crystalline structure on the transition temperature between passive and active oxidation and on the mass loss rate was discussed. The experimental study allows to determine the oxidation rates in incidental and accidental conditions under pO2 = 0.2 and 2 Pa. The variation of the mass loss rates according to the temperature for β-SiC-SiC/PyC/SiC oxidized under pO2 = 0.2 and 2 Pa shows the existence of three domains in the zone of active oxidation. These tests also show the weak impact of the oxygen partial pressure on the mass loss rate of the material in this range of pressure for temperatures lower than 2070 K. On the other hand, beyond 2070 K, an increase of the mass loss rate leading to important damage of the material has been observed, at lower temperature under pO2 = 0.2 Pa than under pO2 = 2 Pa. This variation was associated to the effect of the oxygen partial pressure on the sublimation temperature of SiC. Similar experiments were performed on pre-oxidized samples and on the face without CVD β-SiC coating and both the results are close to the ones obtained for the face with the CVD

  20. 非晶硅/晶体硅(a-Si/c-Si)异质结%Property Investigation of a-Si/c-Si Hetero-Junction Structure

    Institute of Scientific and Technical Information of China (English)

    汪建强; 高华; 张剑; 张松; 李晨; 叶庆好; 孟凡英

    2011-01-01

    通过对非晶硅/晶体硅(a-Si/c-Si)异质结能带不连续、发射结掺杂以及界面态密度进行分析,研究它们对a-Si/c-Si异质结的界面特性,以及a-Si(N+)/c-Si(P)结构电池性能的影响.研究发现,能带不连续以及a-Si发射结高掺杂有利于实现界面复合机制由以悬挂键复合主导的复合机制向由少数载流子复合占主导的SRH(Shockly-Read-Hall)复合机制转变,有效降低界面复合速率.AFORS-HET软件模拟显示:在c-Si(P)衬底掺杂浓度为1.6×1016cm-3时,a-Si(N+)发射结掺杂浓度大于1.5×1020cm-3是获得高电池效率的必要条件;与短路电流密度相比,开路电压受a-Si/c-Si界面态密度影响更明显.%T his paper investigated the influence ot a-hi/c-bi band ottset, amorphous silicon emitter doping concentration and interface defects density on interface property of a-Si/c-Si structure. Band offset in a-Si(N+ )/c-Si(P) hetero-junction and a-Si emitter high level doping is very useful for the transformation of recombination mechanism from dangling bond to SRH (Shockly-Read-Hall). AFORS-HET simulation indicates that a-Si(N+ ) emitter doping level of over 1. 5X1020 cm~3 on c-Si(P) is an indispensable condition for achieving high efficiency. Comparing with density of short circuit current, open circuit voltage of a-Si/c-Si structure cell is much more susceptible to interface defect density.

  1. La visión del otro entre igualdad y diferencia

    Directory of Open Access Journals (Sweden)

    Betina Lilián Prenz

    2004-12-01

    Full Text Available Una innegable evidencia rige el universo humano; nos referimos a la irreducible pluralidad de culturas que lo domina. Dado que las culturas son el horizonte de sentido sin el cual toda experiencia humana sería impensable, es decir, el fondo que hace posible la originaria relación del individuo con el mundo (y cada una de las cuales encierra en sí su propia concepción de lo que somos como hombres, no podemos no tomar en cuenta, pues, la multiplicidad de fisonomías con las que se nos presenta el rostro humano, y con ello, el conjunto de problemas, tanto teóricos como prácticos, que semejante cuestión de la diferencia, o si queremos, de la alteridad, lleva consigo. Si una pregunta pudiese contenerlas todas, plantearíamos, en términos muy generales y que permitiesen ulteriores ra- mificaciones, la siguiente cuestión: si las culturas, múltiples y diferentes, representan el ineludible horizonte de significatividad de la experiencia de los hombres y si éstas son tan radicalmente diferentes, como radicalmente diferentes son los hombres que las habi- tan, Ecómo comportarnos entonces con los demás, o sea, en nuestras relaciones con šel otro’? Naturalmente, hay muchas formas de responder a esta pregunta, por ejemplo, en función o de la perspectiva que la enfoca o del aspecto que en ella preferimos privilegiar: en la amplia gama de cuestiones que semejante pregunta implica, podemos, en efecto, distinguir entre las que pertenecen a un plano axiológico (que tiene que ver con los juicios de valor, con términos como superioridad, inferioridad, relatividad, o a un plano praxeológico (en el que es posible hablar de asimilación del otro o al otro, pero también a un plano epistemológico (que contiene la cuestión fundamental de la comprensión del otro, etc. Entre las varias posibilidades, nosotros tomaremos aquí en cuenta una que intenta no perder de vista los diferentes ejes alrededor de los cuales gira la pregunta misma: se tra- ta de

  2. Magnetron-sputter epitaxy of {beta}-FeSi{sub 2}(220)/Si(111) and {beta}-FeSi{sub 2}(431)/Si(001) thin films at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Liu Hongfei; Tan Chengcheh; Chi Dongzhi [Institute of Materials Research and Engineering (IMRE), A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore)

    2012-07-15

    {beta}-FeSi{sub 2} thin films have been grown on Si(111) and Si(001) substrates by magnetron-sputter epitaxy at 700 Degree-Sign C. On Si(111), the growth is consistent with the commonly observed orientation of [001]{beta}-FeSi{sub 2}(220)//[1-10]Si(111) having three variants, in-plane rotated 120 Degree-Sign with respect to one another. However, on Si(001), under the same growth conditions, the growth is dominated by [-111]{beta}-FeSi{sub 2}(431)//[110]Si(001) with four variants, which is hitherto unknown for growing {beta}-FeSi{sub 2}. Photoelectron spectra reveal negligible differences in the valance-band and Fe2p core-level between {beta}-FeSi{sub 2} grown on Si(111) and Si(001) but an apparent increased Si-oxidization on the surface of {beta}-FeSi{sub 2}/Si(001). This phenomenon is discussed and attributed to the Si-surface termination effect, which also suggests that the Si/Fe ratio on the surface of {beta}-FeSi{sub 2}(431)/Si(001) is larger than that on the surface of {beta}-FeSi{sub 2}(220)/Si(111).

  3. Entre propietarios y migrantes: los encuentros y desencuentros entre Colonos y Aguarunas en el alto mayo”

    Directory of Open Access Journals (Sweden)

    Kenneth E. Garces Montes

    2013-10-01

    Full Text Available La dinámica de conflictos entre colonos y nativos en el Alto Mayo, ha dado como producto continuosenfrentamientos entre caseríos de colonos y comunidades nativas colindantes, así como una seriede procesos judiciales por “usurpación de tierras”, en los cuales no se logra una ejecución efectiva dela sentencia a pesar que esta sea favorable a los nativos, debido a la distancia social que existe entrelos operadores estatales y el conflicto real. Por su parte los mecanismos de convivencia entre colonosy nativos se inician mediante el alquiler de tierras, diseñada como una fórmula temporal para quelos colonos se retiren una vez vencido el plazo del alquiler, sin embargo la ampliación de los plazosprovoca que los mismos adquieran vocación de permanencia.Una serie de actores, de primer, segundo y tercer orden interactúan alrededor de las dos dinámicasde relacionamiento mencionadas; tales como las ONGs, el Estado, organizaciones indígenas, einclusive mafias de traficantes de tierras. Ante esta realidad tan compleja conviene hacer el ejerciciode plantear propuestas de adaptabilidad (o subsistencia de las comunidades nativas, en las quese visualice la supervivencia de lo local frente a lo global en lo que a demarcación de tierras de lascomunidades nativas se refiere.

  4. Relación entre el consumo de drogas y maltrato infantil entre estudiantes universitarios de la universidad en Colombia

    Directory of Open Access Journals (Sweden)

    Monica Rosaura Garcia Baquero

    2015-01-01

    Full Text Available Esta investigación examina la relación entre el uso de drogas en estudiantes de una Universidad Pública en Villavicencio, Colombia, y su relación con el maltrato durante la niñez, utilizando como referente teórico la perspectiva bioecológica. Estudio exploratorio retrospectivo, con una muestra de 313 estudiantes de pregrado. El 10.2% de los encuestados refiere haber sido maltratado en la Infancia y la violencia de mayor uso fue la violencia física seguida de la violencia psicológica. El 56.9% de las estudiantes encuestados han consumido sustancias psicoactivas en algún momento de la vida, y su inicio entre los 13 y los 18 años. Se evidencia maltrato en la infancia con manifestaciones de agresiones físicas, al igual que el consumo de sustancias psicoactivas, pero no se observa una relación estadísticamente significativa entre maltrato durante la infancia y el consumo de sustancias psicoactivas en la muestra estudiada.

  5. SiCp/ZL109复合材料中SiC的界面行为%SiC PARTICLES AND THEIR INTERFACIAL BEHAVIOR IN SiCp/ZL109 COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    隋贤栋; 罗承萍; 欧阳柳章; 骆灼旋

    2000-01-01

    以常规TEM为工具,研究了SiCP/ZL109复合材料中数十个SiC颗粒及其界面,Si优先在SiC表面上形核、长大,形成界面Si,并形成大量SiC/Si界面.靠近SiC界面的Al基体中,普遍存在一层厚度小于1μm的"亚晶铝带",其内有大量位错.SiC与Al、SiC与Si之间虽然没有固定的晶体学位向关系,但是存在下列优先关系:(103)SiC//(111)Al,[110]SiC//[110]Al;(101)SiC//(111)Si;[110]SiC//[11]Si.

  6. On the role of heterolayer relaxation in luminescence response of Si/SiGe:Er structures

    Energy Technology Data Exchange (ETDEWEB)

    Krasilnikova, Ludmila; Stepikhova, Margarita; Drozdov, Yurij; Krasilnik, Zakharii [Institute for Physics of Microstructures, Russian Academy of Sciences, GSP-105, 603950 Nizhny Novgorod (Russian Federation); Chalkov, Vadim; Shengurov, Vladimir [Physico-Technical Research Institute, Nizhny Novgorod State University, Gagarin Ave. 23, 603950 Nizhny Novgorod (Russian Federation)

    2011-03-15

    In this contribution we discuss the luminescence properties of Si/Si{sub 1-x}Ge{sub x}:Er/Si structures being of interest for a laser realization. The influence of the strain relaxation processes that take place in such kind of structures on their photoluminescence response at 1.54 {mu}m has been analyzed. The studies were performed for Si/Si{sub 1-x}Ge{sub x}:Er/Si structures with the different thickness of Si{sub 1-x}Ge{sub x}:Er layers, and consequently the degree of strain relaxation. It is shown that the structural defects arising in Si/Si{sub 1-x}Ge{sub x}:Er/Si structures due to the relaxation play only negligible role in their photoluminescence response. The contribution of the structural defects in the photoluminescence response at 1.54 {mu}m became apparent only in thin partially relaxed Si/Si{sub 1-x}Ge{sub x}:Er/Si structures, the photoluminescence spectra of which are represented by the broad ''defect related'' lines. Intense photoluminescence related with the optically active Er centers of different types was observed for the strained and completely relaxed Si/Si{sub 1-x}Ge{sub x}:Er/Si structures containing thick (d > 1 {mu}m) Si{sub 1-x}Ge{sub x}:Er layers. The external quantum efficiency of these structures reaches the value of 6.3 x 10{sup -5} at T =77 K. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Polarization memory effect in the photoluminescence of nc-Si-SiOx light-emitting structures

    Science.gov (United States)

    Michailovska, Katerina; Indutnyi, Ivan; Shepeliavyi, Petro; Sopinskyy, Mykola

    2016-06-01

    The polarization memory (PM) effect in the photoluminescence (PL) of the porous nc-Si-SiOx light-emitting structures, containing nanoparticles of silicon (nc-Si) in the oxide matrix and passivated in a solution of hydrofluoric acid (HF), has been investigated. The studied nc-Si-SiOx structures were produced by evaporation of Si monoxide (SiO) powder in vacuum and oblique deposition on Si wafer, and then the deposited silicon oxide (SiOx) films were annealed in the vacuum at 975 °C to grow nc-Si. It was found that the PM effect in the PL is observed only after passivation of nanostructures: during etching in HF solution, the initial symmetric nc-Si becomes asymmetric elongated. It was also found that in investigated nanostructures, there is a defined orientational dependence of the PL polarization degree ( ρ) in the sample plane which correlates with the orientation of SiOx nanocolumns, forming the structure of the porous layer. The increase of the ρ values in the long-wavelength spectral range with time of HF treatment can be associated with increasing of the anisotropy of large Si nanoparticles. The PM effect for this spectral interval can be described by the dielectric model. In the short-wavelength spectral range, the dependence of the ρ values agrees qualitatively with the quantum confinement effect.

  8. Polarization memory effect in the photoluminescence of nc-Si-SiOx light-emitting structures.

    Science.gov (United States)

    Michailovska, Katerina; Indutnyi, Ivan; Shepeliavyi, Petro; Sopinskyy, Mykola

    2016-12-01

    The polarization memory (PM) effect in the photoluminescence (PL) of the porous nc-Si-SiOx light-emitting structures, containing nanoparticles of silicon (nc-Si) in the oxide matrix and passivated in a solution of hydrofluoric acid (HF), has been investigated. The studied nc-Si-SiOx structures were produced by evaporation of Si monoxide (SiO) powder in vacuum and oblique deposition on Si wafer, and then the deposited silicon oxide (SiOx) films were annealed in the vacuum at 975 °C to grow nc-Si. It was found that the PM effect in the PL is observed only after passivation of nanostructures: during etching in HF solution, the initial symmetric nc-Si becomes asymmetric elongated. It was also found that in investigated nanostructures, there is a defined orientational dependence of the PL polarization degree (ρ) in the sample plane which correlates with the orientation of SiOx nanocolumns, forming the structure of the porous layer. The increase of the ρ values in the long-wavelength spectral range with time of HF treatment can be associated with increasing of the anisotropy of large Si nanoparticles. The PM effect for this spectral interval can be described by the dielectric model. In the short-wavelength spectral range, the dependence of the ρ values agrees qualitatively with the quantum confinement effect.

  9. Polarization memory effect in the photoluminescence of nc-Si-SiOx light-emitting structures.

    Science.gov (United States)

    Michailovska, Katerina; Indutnyi, Ivan; Shepeliavyi, Petro; Sopinskyy, Mykola

    2016-12-01

    The polarization memory (PM) effect in the photoluminescence (PL) of the porous nc-Si-SiOx light-emitting structures, containing nanoparticles of silicon (nc-Si) in the oxide matrix and passivated in a solution of hydrofluoric acid (HF), has been investigated. The studied nc-Si-SiOx structures were produced by evaporation of Si monoxide (SiO) powder in vacuum and oblique deposition on Si wafer, and then the deposited silicon oxide (SiOx) films were annealed in the vacuum at 975 °C to grow nc-Si. It was found that the PM effect in the PL is observed only after passivation of nanostructures: during etching in HF solution, the initial symmetric nc-Si becomes asymmetric elongated. It was also found that in investigated nanostructures, there is a defined orientational dependence of the PL polarization degree (ρ) in the sample plane which correlates with the orientation of SiOx nanocolumns, forming the structure of the porous layer. The increase of the ρ values in the long-wavelength spectral range with time of HF treatment can be associated with increasing of the anisotropy of large Si nanoparticles. The PM effect for this spectral interval can be described by the dielectric model. In the short-wavelength spectral range, the dependence of the ρ values agrees qualitatively with the quantum confinement effect. PMID:27255897

  10. 固相烧结SiC陶瓷%Solid State Sintered SiC Ceramics

    Institute of Scientific and Technical Information of China (English)

    武安华; 曹文斌; 李江涛; 葛昌纯

    2001-01-01

    Solid state sintered SiC ceramics were obtained by hot pressing of α-SiC, β-SiC and 1%α-SiC +99%β-SiC powders with boride and carbon as additives. Two phase transforms of 3C→6H and 6H→4H occurred during sintering process. The in situ toughening SiC ceramics can't be obtained only by rod-like grains without the weak grain-boundary.%实验采用α-SiC、β-SiC和(1%α-SiC +99%β-SiC)作为起始粉末,以B、C为添加剂,热压烧结SiC陶瓷。其烧结过程中尽管发生多型体之间的转变,但其表现形式为α-SiC的6H→4H和β-SiC的3C→6H两种形式。尽管有大量的长柱状颗粒生成,但是由于没有弱的界面结合,不能原位增强。

  11. Study on in-situ Mg2Si/Al-Si composites with different compositions

    Institute of Scientific and Technical Information of China (English)

    Jing Qingxiu; Zhang Caixia; Huang Xiaodong

    2009-01-01

    Effects of chemical composition and heat treatment on microstructures and mechanical properties of in-situ Mg2Si/Al-Si composites were investigated. It was found that, in the microstructure of an Al-5.7wt% Mg2Si composite with 8.2wt% extra Si, the binary eutectic Mg2Si locates at the grain boundaries with an undeveloped Chinese script-like morphology, and the primary α-Al is formed into a cell structure due to the selective modification effect of the modifiers of mischmetal and Strontium salt; whereas in the composite with a near Al-Mg2Si eutectic composition and little extra Si content, the intercrescence eutectic Mg2Si formed with the binary eutectic a-Al grows into integrated Chinese script-like shape. As Si content increases, the eutectic Mg2Si dendrite becomes coarser in morphology but less in volum e fraction. Hardness and tensile strength of the cast Mg2Si/Al-Si composites do not increase with increasing of Mg content, but they are related to the size and morphology of the eutectic and primary Mg2Si phases. Heat treatment with optimal parameters is an effective way to improve the properties of the in-situ composites.

  12. Chemical compatibility issues associated with use of SiC/SiC in advanced reactor concepts

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Dane F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-09-01

    Silicon carbide/silicon carbide (SiC/SiC) composites are of interest for components that will experience high radiation fields in the High Temperature Gas Cooled Reactor (HTGR), the Very High Temperature Reactor (VHTR), the Sodium Fast Reactor (SFR), or the Fluoride-cooled High-temperature Reactor (FHR). In all of the reactor systems considered, reactions of SiC/SiC composites with the constituents of the coolant determine suitability of materials of construction. The material of interest is nuclear grade SiC/SiC composites, which consist of a SiC matrix [high-purity, chemical vapor deposition (CVD) SiC or liquid phase-sintered SiC that is crystalline beta-phase SiC containing small amounts of alumina-yttria impurity], a pyrolytic carbon interphase, and somewhat impure yet crystalline beta-phase SiC fibers. The interphase and fiber components may or may not be exposed, at least initially, to the reactor coolant. The chemical compatibility of SiC/SiC composites in the three reactor environments is highly dependent on thermodynamic stability with the pure coolant, and on reactions with impurities present in the environment including any ingress of oxygen and moisture. In general, there is a dearth of information on the performance of SiC in these environments. While there is little to no excess Si present in the new SiC/SiC composites, the reaction of Si with O2 cannot be ignored, especially for the FHR, in which environment the product, SiO2, can be readily removed by the fluoride salt. In all systems, reaction of the carbon interphase layer with oxygen is possible especially under abnormal conditions such as loss of coolant (resulting in increased temperature), and air and/ or steam ingress. A global outline of an approach to resolving SiC/SiC chemical compatibility concerns with the environments of the three reactors is presented along with ideas to quickly determine the baseline compatibility performance of SiC/SiC.

  13. The Stellar Imager (SI) Vision Mission

    OpenAIRE

    Carpenter, Kenneth G.; Schrijver, Carolus J.; Karovska, Margarita; Team, SI Vision Mission

    2006-01-01

    The Stellar Imager (SI) is a UV-Optical, Space-Based Interferometer designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and of the Universe in general and asteroseismic imaging of stellar interiors. SI is identified as a "Flagship and Landmark Discovery Mission" in the 2005 Sun Solar System Connection (SSSC) Roadmap and as a candidate for a "Pathways to Life Observatory" in the Exploration of the Universe Division (EUD) Roadmap (May, 2005). SI will revolutionize ...

  14. siRNA的应用

    Institute of Scientific and Technical Information of China (English)

    孟立根; 马清河; 王安忠; 秦俊文

    2004-01-01

    RNAi(RNA interference,RNA阻断)当初是在研究绦虫C elegans时观测到的一种现象。当将双链的RNA(double stranded RNA;dsRNA)导人体内后,与这种双链RNA相同性较高的mRNA将被特异性地抑制或者消除。除了绦虫之外,RNAi已被作为一种研究基因功能的有效工具,广泛运用于植物、真菌、线虫、果蝇以及哺乳动物,并获得了好的效果。近来使用短链(21~23碱基对)siRNA(short interfering RNA)也获得了同样的效果。siRNA与传统RNA干涉技术相比具有极大的优越

  15. SiLix-C Nanocomposites

    Science.gov (United States)

    Henry, Francois

    2015-01-01

    For this Phase II project, Superior Graphite Co., in collaboration with the Georgia Institute of Technology and Streamline Nanotechnologies, Inc., developed, explored the properties of, and demonstrated the enhanced capabilities of novel nanostructured SiLix-C anodes. These anodes can retain high capacity at a rapid 2-hour discharge rate and at 0 C when used in Li-ion batteries. In Phase I, these advanced anode materials had specific capacity in excess of 1,000 mAh/g, minimal irreversible capacity losses, and stable performance for 20 cycles at C/1. The goals in Phase II were to develop and apply a variety of novel nanomaterials, fine-tune the properties of composite particles at the nanoscale, optimize the composition of the anodes, and select appropriate binder and electrolytes. In order to achieve a breakthrough in power characteristics of Li-ion batteries, the team developed new nanostructured SiLix-C anode materials to offer up to 1,200 mAh/g at C/2 at 0 C.

  16. Concordância entre citologia, colposcopia e histopatologia cervical Agreement between cytology, colposcopy and cervical histopathology

    Directory of Open Access Journals (Sweden)

    Letícia Maria Correia Katz

    2010-08-01

    Full Text Available OBJETIVO: avaliar a concordância da citologia convencional por Papanicolaou repetida no momento da colposcopia com os achados colposcópicos e a histopatologia. MÉTODOS: o estudo foi realizado no Laboratório Central de Saúde Pública do Estado de Pernambuco (LACEN, de janeiro a julho de 2008, em 397 mulheres com exame citopatológico alterado encaminhadas para avaliação colposcópica. No momento da colposcopia, repetiu-se a citologia em meio convencional, pesquisando-se os achados colposcópicos anormais. A nomenclatura citológica utilizada foi a de Bethesda e a histopatológica, da Organização Mundial de Saúde. A citologia no momento da colposcopia e a colposcopia foram comparadas entre si e com o resultado do histopatológico obtido por biópsia dirigida. A concordância entre os métodos foi avaliada pelo coeficiente Kappa (K, além do teste χ2 a um nível de significância de 5%. RESULTADOS: foi encontrada uma concordância fraca entre a citologia realizada no momento da colposcopia e a colposcopia, K=0,33 (IC95%=0,21-0,45 e entre a colposcopia e a histopatologia, K=0,35 (IC95%=0,39-0,51. Para a concordância entre citologia no momento da colposcopia e histopatologia, o Kappa foi de 0,41 (IC95%=0,29-0,530, considerado moderado. CONCLUSÕES: houve melhor concordância entre citologia e histopatologia do que entre colposcopia e citologia ou colposcopia e histopatologia.PURPOSE: to evaluate the agreement between conventional cytology using the Papanicolaou test, repeated at the time of colposcopy, with colposcopic and histopathological findings. METHODS: the study was carried out at the central public health laboratory of the state of Pernambuco between January and July, 2008, involving 397 women referred for colposcopic evaluation following an abnormal cervical smear test. Cytology was repeated at the time of colposcopy using conventional method, with particular attention being paid to the presence of abnormal colposcopic findings

  17. Pd-Si binary bulk metallic glass

    Institute of Scientific and Technical Information of China (English)

    YAO KeFu; CHEN Na

    2008-01-01

    Pd80+xSi20-x (x=0, 1, and 2) binary metallic glasses with the diameter ranging from 7 to 8 mm were prepared by a combination of fluxing and water quenching or air cooling. Thermal analysis results show that with increasing Si content, the glass transition temperature Tg, the initial crystallization temperature Tx and the onset crystalliza-tion temperature Tp of Pd-Si binary glassy alloys increase. Moreover, the super-cooled liquid region reaches 61 K. It indicates that Pd-Si binary alloys possess large glass forming ability, which can be greatly improved by fluxing treatment.

  18. Pd-Si binary bulk metallic glass

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Pd80+xSi20-x (x=0,1,and 2) binary metallic glasses with the diameter ranging from 7 to 8 mm were prepared by a combination of fluxing and water quenching or air cooling. Thermal analysis results show that with increasing Si content,the glass transition temperature Tg,the initial crystallization temperature Tx and the onset crystalliza-tion temperature Tp of Pd-Si binary glassy alloys increase. Moreover,the super-cooled liquid region reaches 61 K. It indicates that Pd-Si binary alloys possess large glass forming ability,which can be greatly improved by fluxing treatment.

  19. SiD Letter of Intent

    Energy Technology Data Exchange (ETDEWEB)

    Aihara, H., (Ed.); Burrows, P., (Ed.); Oreglia, M., (Ed.); Berger, E.L.; Guarino, V.; Repond, J.; Weerts, H.; Xia, L.; Zhang, J.; /Argonne, HEP; Zhang, Q.; /Argonne, HEP /Beijing, Inst. High Energy Phys.; Srivastava, A.; /Birla Inst. Tech. Sci.; Butler, J.M.; /Boston U.; Goldstein, Joel; Velthuis, J.; /Bristol U.; Radeka, V.; /Brookhaven; Zhu, R.-Y.; /Caltech.; Lutz, P.; /DAPNIA, Saclay; de Roeck, A.; Elsener, K.; Gaddi, A.; Gerwig, H.; /CERN /Cornell U., LNS /Ewha Women' s U., Seoul /Fermilab /Gent U. /Darmstadt, GSI /Imperial Coll., London /Barcelona, Inst. Microelectron. /KLTE-ATOMKI /Valencia U., IFIC /Cantabria Inst. of Phys. /Louis Pasteur U., Strasbourg I /Durham U., IPPP /Kansas State U. /Kyungpook Natl. U. /Annecy, LAPP /LLNL, Livermore /Louisiana Tech. U. /Paris U., VI-VII /Paris U., VI-VII /Munich, Max Planck Inst. /MIT, LNS /Chicago, CBC /Moscow State U. /Nanjing U. /Northern Illinois U. /Obninsk State Nucl. Eng. U. /Paris U., VI-VII /Strasbourg, IPHC /Prague, Inst. Phys. /Princeton U. /Purdue U. /Rutherford /SLAC /SUNY, Stony Brook /Barcelona U. /Bonn U. /UC, Davis /UC, Santa Cruz /Chicago U. /Colorado U. /Delhi U. /Hawaii U. /Helsinki U. /Indiana U. /Iowa U. /Massachusetts U., Amherst /Melbourne U. /Michigan U. /Minnesota U. /Mississippi U. /Montenegro U. /New Mexico U. /Notre Dame U. /Oregon U. /Oxford U. /Ramon Llull U., Barcelona /Rochester U. /Santiago de Compostela U., IGFAE /Hefei, CUST /Texas U., Arlington /Texas U., Dallas /Tokyo U. /Washington U., Seattle /Wisconsin U., Madison /Wayne State U. /Yale U. /Yonsei U.

    2012-04-11

    This document presents the current status of the Silicon Detector (SiD) effort to develop an optimized design for an experiment at the International Linear Collider. It presents detailed discussions of each of SiD's various subsystems, an overview of the full GEANT4 description of SiD, the status of newly developed tracking and calorimeter reconstruction algorithms, studies of subsystem performance based on these tools, results of physics benchmarking analyses, an estimate of the cost of the detector, and an assessment of the detector R and D needed to provide the technical basis for an optimised SiD.

  20. L’image sonore contemporaine : entre misère symbolique et imaginaire sonore

    Directory of Open Access Journals (Sweden)

    Vincent Tiffon

    2007-05-01

    Full Text Available L’histoire de la musique peut s’écrire comme l’évolution progressive mais déterminante de deux grands paradigmes technologiques, celui de l’écriture et celui du son. L’enregistrement sonore modifie en profondeur l’économie de la musique en inventant notamment de nouveaux modes d’invention du sonore et de nouvelles pratiques d’écoute du sonore. On élargit alors le domaine du musical en inventant l’image sonore. À l’instar des autres arts de studio, la photographie, la cinématographie, la vidéo…, la phonographie prend le réel comme matériau immédiat. L’effet de réalité qui en résulte conduit au glissement progressif de la musique comme objet cultuel (avant le xive siècle, à la musique comme objet industriel (depuis 1970 en passant par la musique comme objet culturel (entre le xive siècle et le xxe siècle ; ce faisant, le risque d’une « désorientation » est bien réel. D’où une cartographie floue entre culture, art et phénomènes de société. L’image sonore semble s’inscrire entre « misère symbolique » et imaginaire, entre l’industrie musicale et l’avant-garde.The history of music can be written as the gradual yet decisive evolution of two great technological paradigms: the paradigms of writing and of sound. Sound recording has profoundly altered the organization of music, notably through the invention of new modes of sound invention and new practices of listening to sound phenomena. It is precisely at this point that the field of music has been widened by the invention of the sound image. After the fashion of the other arts of the studio (photography, cinematography, video and so on, phonography has reality itself as its unmediated material. The resulting reality effect has led to the gradual shift from music as liturgical object (before the 14th century to music as industrial object (since 1970 via music as cultural object (between the 14th century and the 20th century. In

  1. Stress-impedance effects in layered FeSiB/Cu/FeSiB films with a meander line structure

    International Nuclear Information System (INIS)

    Stress-impedance (SI) effects were realized in layered FeSiB/Cu/FeSiB films with a meander line structure by magnetron sputtering on thin glass substrate. The SI effects were studied in the frequency range of 1-40MHz for the layered FeSiB/Cu/FeSiB films with different film thickness of FeSiB film and Cu layer. Experimental results show that the values of SI ratio increase nearly linear with the deflection of the layered FeSiB/Cu/FeSiB films at high frequencies, and a large negative SI ratio of -18.3% at a frequency of 25MHz with the deflection of 1000μm is obtained in the layered FeSiB/Cu/FeSiB films with a thicker FeSiB film, which is very attractive for the applications of stress sensors

  2. Optimization of Waveguide Structure for Tunable Optical Switch in Si/SiGe System

    Institute of Scientific and Technical Information of China (English)

    Seongjae; Boo; Won-Taek; Han

    2003-01-01

    A new electro-optical device using Si/SiGe-system with two parallel ridge waveguides is proposed for optical switching and the optimization of the structure for a single mode operation is investigated.

  3. Thermogravimetric and microscopic analysis of SiC/SiC materials with advanced interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Windisch, C.F. Jr.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States); Snead, L.L. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    The chemical stability of SiC/SiC composites with fiber/matrix interfaces consisting of multilayers of SiC/SiC and porous SiC have been evaluated using a thermal gravimetric analyzer (TGA). Previous evaluations of SiC/SiC composites with carbon interfacial layers demonstrated the layers are not chemically stable at goal use temperatures of 800-1100{degrees}C and O{sub 2} concentrations greater than about 1 ppm. No measureable mass change was observed for multilayer and porous SiC interfaces at 800-1100{degrees}C and O{sub 2} concentrations of 100 ppm to air; however, the total amount of oxidizable carbon is on the order of the sensitivity of the TGA. Further studies are in progress to evaluate the stability of these materials.

  4. W-Mo-Si/SiC Oxidation Protective Coating for Carbon/Carbon Composites

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A W-Mo-Si/SiC double-layer oxidation protective coating for carbon/carbon (C/C) composites was prepared by a two-step pack cementation technique. XRD (X-ray diffraction) and SEM (scanning electron microscopy)results show that the coating obtained by the first step pack cementation was a thin inner buffer layer of SiC with some cracks and pores, and a new phase of (WxMo1-x)Si2 appeared after the second step pack cementation. Oxidation test shows that, after oxidation in air at 1773 K for 175 h and thermal cycling between 1773 K and room temperature for 18 times, the weight loss of the W-Mo-Si/SiC coated C/C composites was only 2.06%. The oxidation protective failure of the W-Mo-Si/SiC coating was attributed to the formation of some penetrable cracks in the coating.

  5. Fabrication and characteristics of the nc-Si/c-Si heterojunction MAGFET

    Institute of Scientific and Technical Information of China (English)

    Zhao Xiaofeng; Wen Dianzhong

    2009-01-01

    A MAGFET using an nc-Si/c-Si heterojunction as source and drain was fabricated by CMOS technology, using two ohm-contact electrodes as Hall outputs on double sides of the channel situated 0.7L from the source. The experimental results show that when V_(DS) = -7.0 V, the magnetic sensitivity of the single nc-Si/c-Si heterojunction magnetic metal oxide semiconductor field effect transistor (MAGFET) with an L : W ratio of 2 : 1 is 21.26 mV/T,and that with an L : W ratio of 4 : 1 is 13.88 mV/T. When the outputs of double nc-Si/c-Si heterojunction MAGFETs with an L : W ratio of 4 : 1 are in series, their magnetic sensitivity is 22.74 mV/T, which is an improvement of about 64% compared with that of a single nc-Si/c-Si heterojunction MAGFET.

  6. Strain relaxation in nano-patterned strained-Si/SiGe heterostructure on insulator

    International Nuclear Information System (INIS)

    In order to evaluate the strain stability, arrays of strained Si/SiGe nano-stripes and nano-pillars were fabricated by Electron-Beam Lithography (EBL) and Reactive-Ion Etching (RIE). The strain relaxation in the patterned strained Si on SiGe-on-insulator (SGOI) was investigated by high-resolution UV micro-Raman spectroscopy. The Raman measurements before and after patterning indicate that most of the strain in the top strained Si is maintained until scaling down to 300 nm, and relaxation of <15% is observed in pillars with a dimension of 150 nm x 150 nm. In the nano-patterned heterostructure strained Si/SiGe, the observed relaxation is small, which is mainly attributed to the fully relaxed and dislocation-free SiGe virtual substrate fabricated by modified Ge condensation.

  7. Recycling of Al-Si die casting scraps for solar Si feedstock

    Science.gov (United States)

    Seo, Kum-Hee; Jeon, Je-Beom; Youn, Ji-Won; Kim, Suk Jun; Kim, Ki-Young

    2016-05-01

    Recycling of aluminum die-casting scraps for solar-grade silicon (SOG-Si) feedstock was performed successfully. 3 N purity Si was extracted from A383 die-casting scrap by using the combined process of solvent refining and an advanced centrifugal separation technique. The efficiency of separating Si from scrap alloys depended on both impurity level of scraps and the starting temperature of centrifugation. Impurities in melt and processing temperature governed the microstructure of the primary Si. The purity of Si extracted from the scrap melt was 99.963%, which was comparable to that of Si extracted from a commercial Al-30 wt% Si alloy, 99.980%. The initial purity of the scrap was 2.2% lower than that of the commercial alloy. This result confirmed that die-casting scrap is a potential source of high-purity Si for solar cells.

  8. Nanoscale structure of Si/SiO2/organics interfaces.

    Science.gov (United States)

    Steinrück, Hans-Georg; Schiener, Andreas; Schindler, Torben; Will, Johannes; Magerl, Andreas; Konovalov, Oleg; Li Destri, Giovanni; Seeck, Oliver H; Mezger, Markus; Haddad, Julia; Deutsch, Moshe; Checco, Antonio; Ocko, Benjamin M

    2014-12-23

    X-ray reflectivity measurements of increasingly more complex interfaces involving silicon (001) substrates reveal the existence of a thin low-density layer intruding between the single-crystalline silicon and the amorphous native SiO2 terminating it. The importance of accounting for this layer in modeling silicon/liquid interfaces and silicon-supported monolayers is demonstrated by comparing fits of the measured reflectivity curves by models including and excluding this layer. The inclusion of this layer, with 6-8 missing electrons per silicon unit cell area, consistent with one missing oxygen atom whose bonds remain hydrogen passivated, is found to be particularly important for an accurate and high-resolution determination of the surface normal density profile from reflectivities spanning extended momentum transfer ranges, now measurable at modern third-generation synchrotron sources. PMID:25401294

  9. Relaciones entre el Congreso Nacional y el Poder Judicial: La Importancia de la Apertura

    Directory of Open Access Journals (Sweden)

    Sebastián Soto Velasco

    2007-01-01

    Full Text Available El presente trabajo analiza las relaciones entre el Congreso Nacional y el Poder Judicial a través de dos instituciones existentes en nuestro ordenamiento: el proceso de nombramiento de Ministros de la Corte Suprema y los informes que esta última envía al Congreso Nacional en ciertos proyectos de ley. En el caso de las nominaciones de Ministros a la Corte Suprema se estudia como ha operado el sistema desde la incorporación del Senado en 1997 hasta el año 2005. Se analiza cómo la transparencia del proceso, la posibilidad de conocer la historia profesional del nominado y audiencias abiertas contribuirían a incentivar una decisión centrada en criterios de calidad. El documento también se centra en el contenido y la influencia de los informes que envía la Corte Suprema al Congreso Nacional con ocasión de la tramitación de proyectos de ley que contienen normas que modifican la organización o atribuciones de los tribunales de justicia. En esta instancia, permitir el acceso a los informes también tendría positivas consecuencias. En definitiva, aunque hay otras vías de comunicación entre el Congreso y el Poder Judicial, se profundiza únicamente en las mencionadas pues del estudio se concluye que ambas tenderían a aumentar el potencial que de suyo ya tienen si se incorpora apertura en los procesosThis paper analyzes the relationship between the Chilean Congress and Judicial power, focusing on two institutions: the nomination process to appoint Supreme Court justices and the reports that the Supreme Court is constitutionally obligated to send to the Congress when specific types of bills are introduced. The appointment of Supreme Court candidates is studied from the Senate's incorporation in the process from 1997 until 2005. The author states that a more transparent process, including the publication of the candidate's backgrounds and public hearings, would increase the incentives to nominate the most qualified candidates. The paper also

  10. RELAÇÕES E PARALELOS ENTRE ROUSSEAU E A ECOLOGIA RADICAL CONTEMPORÂNEA

    Directory of Open Access Journals (Sweden)

    Eduardo Cardoso Braga

    2013-12-01

    Full Text Available Verificou-se que, embora haja uma série de publicações contextualizando o pensamento de Rousseau no debate contemporâneo sobre a filosofia ambiental, a participação de seu pensamento é ainda diminuta. Relacionaram-se então alguns conceitos fundamentais da ecologia radical contemporânea com a filosofia rousseauniana. Constatou-se que ambos procedem a uma crítica radical do antropocentrismo, propondo, como alternativa, um ecocentrismo. Concentrou-se no conceito de “valor intrínseco” da natureza e suas implicações éticas no relacionamento entre homem e ambiente. No caso de Rousseau essa relação se desenvolve por meio de uma profunda análise das paixões amor-de-si e amor-próprio. Constatou-se que tanto a ecologia radical como Rousseau não acreditam na possibilidade de uma volta ao estado de natureza, porém é possível recuperar a experiência feliz da ligação com a totalidade da vida, que esse estado proporcionava aos homens. A recuperação somente pode ocorrer em outro registro, em meio à civilização e à tecnologia. Mostrou-se a importância da estratégia rousseauniana nessa questão ao propor a expansão do amor-próprio até uma dimensão de totalidade, recuperando dessa forma a possibilidade de uma vida feliz e significativa (boa-vida. Entretanto, tanto Rousseau como os partidários da ecologia radical consideram as dificuldades em se realizar tanto a experiência da totalidade como da vida ética na relação entre homem e natureza, dada as condições da contemporaneidade.

  11. Traducción automatizada de programas entre lenguajes de operaciones

    Directory of Open Access Journals (Sweden)

    Diego Ordóñez Camacho

    2012-06-01

    Full Text Available Los lenguajes de operaciones se usan para programar, en procedimientos organizados, las instrucciones a ser ejecutadas por una máquina, para realizar distintos tipos de operaciones. Para poder importar procedimientos existentes realizados en un lenguaje de operaciones dado, en frameworks de programación específicos para el diseño de operaciones, es necesario contar con traductores entre el lenguaje en que ha sido programado el procedimiento, y el lenguaje interno utilizado por el framework de diseño. La construcción de estos traductores puede ser automatizada si se establece un mapeo entre producciones equivalentes de las gramáticas de los lenguajes fuente y destino. Las producciones se pueden considerar equivalentes cuando a pesar de tener una sintaxis diferente, tienen la misma intención semántica y pueden ser equiparadas con un árbol de sintaxis abstracta en común. Debido a ciertas diferencias sintácticas, en ocasiones este árbol sintáctico común no puede ser hallado directamente. Esto se vuelve posible, sin embargo, al realizar en primer lugar ciertas transformaciones a los programas. Este artículo presenta un acercamiento específico a la construcción de reglas de transformación para resolver estas diferencias.Abstract:Operations languages are used to program the procedures that instruct machinery to perform specific operations. To import procedures in a given operations language, into a dedicated tool for designing operations, language translators are needed to translate those procedures to the design tool's internal operations language. The construction of these translators can be automated by mapping equivalent productions in the grammar of source and target language. Productions are considered equivalent when, in spite of a differing syntax, they have the same intended semantics and can be matched to a same abstract syntax tree. For some corresponding productions, due to syntactic differences, such a common abstract

  12. P-type poly-Si prepared by low-temperature aluminum-induced crystallization and doping for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Yasuhiro; Yu, Zhenrui; Morales-Acevedo, Arturo [CINVESTAV-IPN, Mexico, D.F. (Mexico)

    2000-07-01

    P-type poly-Si thin films prepared by low temperature aluminum-induced crystallization and doping are reported. The starting material was boron-doped a-Si:H prepared by PECVD on glass substrates. Aluminum layers with different thickness were evaporated on a-Si:H surface and conventional thermal annealing was performed at temperatures ranging from 300 to 550 Celsius degrees. XRD, SIMS, and Hall effect measurements were carried out to characterize the annealed Al could be crystallized at temperature as low as 300 Celsius degrees in 60 minutes. This material has high carrier concentration as well as high Hall mobility and can be used as a p-layer of seed layer for thin film poly-Si solar cells. The technique reported here is compatible with PECVD process. [Spanish] Se informa sobre la preparacion de peliculas delgadas tipo P y Poli-Si mediante la cristalizacion inducida de aluminio a baja temperatura y el dopado. El material inicial era de boro dopado y a-Si:H preparado PECVD sobre substratos de vidrio. Se evaporaron capas de aluminio de diferente espesor sobre una superficie de a-Si:H y se llevo a cabo un destemplado termico convencional a temperaturas que varian entre 300 y 500 grados Celsius. Se llevaron a cabo mediciones de XRB, SIMS y del efecto Hall para caracterizar el aluminio destemplado para que pudiera ser cristalizado a temperaturas tan bajas como 300 grados Celsius en 60 minutos. Este material tiene una alta concentracion portadora asi como una alta movilidad Hall y puede usarse como una capa de semilla para celdas solares de pelicula delgada Poli-Si. La tecnica reportada aqui es compatible con el proceso PECVD.

  13. Raman scattering in Si/SiGe nanostructures: Revealing chemical composition, strain, intermixing, and heat dissipation

    Energy Technology Data Exchange (ETDEWEB)

    Mala, S. A.; Tsybeskov, L., E-mail: tsybesko@njit.edu [Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102 (United States); Lockwood, D. J.; Wu, X.; Baribeau, J.-M. [National Research Council, Ottawa, Ontario K1A 0R6 (Canada)

    2014-07-07

    We present a quantitative analysis of Raman scattering in various Si/Si{sub 1-x}Ge{sub x} multilayered nanostructures with well-defined Ge composition (x) and layer thicknesses. Using Raman and transmission electron microscopy data, we discuss and model Si/SiGe intermixing and strain. By analyzing Stokes and anti-Stokes Raman signals, we calculate temperature and discuss heat dissipation in the samples under intense laser illumination.

  14. Fabrication and Properties of Ti3SiC2/SiC Composites

    Institute of Scientific and Technical Information of China (English)

    YIN Hongfeng; FAN Qiang; REN Yun; ZHANG Junzhan

    2008-01-01

    Ti3SiC2/SiC composites were fabricated by reactive hot pressing method. Effects of hot pressing temperature, the content and panicle size of SiC on phase composition, densification, mechanical properties and behavior of stress-strain of the composites were investigated. The results showed that:(1)Hot-pressing temperature influenced the phase composition of Ti3SiC2/SiC composites. The flexural strength and fracture toughness of composites increased with hot pressing temperature.(2)It became more difficult for the composites to densify when the content of SiC in composites increased. It need be sintered at higher temperature to get denser composite. The flexural strength and fracture toughness of composites increased when the content of SiC added in composites increased. However, when the content of SiC reached 50 wt%, the flexural strength and fracture toughness of composites decreased due to high content of pore in composites.(3)When the content of SiC was same, Ti3SiC2/SiC composites were denser while the particle size of SiC added in composites is 12.8μm compared with the composites that the particle size of SiC added is 3μm.The flexural strength and fracture toughness of composites increased with the increase of particle size of SiC added in composites.(4)Ti3SiC2/SiC composites were non-brittle fracture at room temperature.

  15. Minimum bar size for flexure testing of irradiated SiC/SiC composite

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, G.E.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-03-01

    This report covers material presented at the IEA/Jupiter Joint International Workshop on SiC/SiC Composites for Fusion structural Applications held in conjunction with ICFRM-8, Sendai, Japan, Oct. 23-24, 1997. The minimum bar size for 4-point flexure testing of SiC/SiC composite recommended by PNNL for irradiation effects studies is 30 {times} 6 {times} 2 mm{sup 3} with a span-to-depth ratio of 10/1.

  16. Passivation of surface-nanostructured f-SiC and porous SiC

    DEFF Research Database (Denmark)

    Ou, Haiyan; Lu, Weifang; Ou, Yiyu;

    The further enhancement of photoluminescence from nanostructured fluorescent silicon carbide (f-SiC) and porous SiC by using atomic layer deposited (ALD) Al2O3 is studied in this paper.......The further enhancement of photoluminescence from nanostructured fluorescent silicon carbide (f-SiC) and porous SiC by using atomic layer deposited (ALD) Al2O3 is studied in this paper....

  17. Nanocrystal Formation in Si Implanted Thin SiO2 Layers under the Influence of an Absorbing Interface

    OpenAIRE

    Mueller, T.; Heinig, K. -H.; Moeller, W.

    2002-01-01

    Kinetic 3D lattice Monte Carlo studies are presented on Si nanocrystal (NC) formation by phase separation in 1 keV Si implanted thin SiO2 films. The simulation start from Si depth profiles calculated using the dynamic, high-fluence binary collision code TRIDYN. From the initial Si supersaturation, NCs are found to form either by nucleation, growth and Ostwald ripening at low Si concentrations. Or at higher concentrations, non-spherical, elongated Si structures form by spinodal decomposition, ...

  18. La disciplina entre las disposiciones legales y los actores escolares

    Directory of Open Access Journals (Sweden)

    Nancy Palacios Mena

    2013-01-01

    Full Text Available Este artículo presenta una descripción del funcionamiento de la disciplina escolar en una institución educativa de secundaria en Colombia. Tiene como objetivo explicar el origen del conflicto disciplinario, las situaciones que lo generan, la forma como la institución trata de lograr y mantener la disciplina, las explicaciones que cada uno de los actores da a las situaciones conflictivas y la manera como son vividas por ellos. El diseño metodológico de la investigación combinó una encuesta, entrevistas y el análisis de documentos de la institución educativa. El análisis de los datos se hace a la luz de planteamientos sociológicos que reconocen la enorme importancia que ejercen las estructuras sociales sobre la forma de pensar y actuar de los individuos, pero también resaltan la gran capacidad de los actores sociales para amoldarse a dichas estructuras y a través de sus ideas y acciones darle una dinámica propia al tipo de relaciones que establecen entre individuos en sus entornos de vida más inmediatos. Se pudo concluir que sobre la disciplina escolar no hay unidad de criterio entre los docentes, los directivos y los estudiantes, ni en su definición, ni en su importancia, ni en los medios para conseguirla; dichas diferencias producen tensiones y desacuerdos entre los miembros de la comunidad educativa.

  19. SiC-Si-ZrSiO4 Multiphase Oxidation Protective Coating for Carbon/Carbon Composites

    Institute of Scientific and Technical Information of China (English)

    Yulei ZHANG; Hejun LI; Qiangang FU; Kezhi LI; Dangshe HOU

    2008-01-01

    In order to improve the anti-oxidation property of carbon/carbon (C/C) composites,a novel SiC-Si-ZrSiO4 multiphase oxidation protective coating was produced on the surface of C/SiC coated carbon/carbon compos-ites by a pack cementation technique.The phase composition and microstructure of the as-prepared coatings were characterized by XRD (X-ray diffraction),SEM (scanning electron microscopy) and EDS (energy dis-persive spectroscopy).Oxidation behavior of the multiphase coated C/C composites was also investigated.It showed that the as-prepared coating characterized by excellent oxidation resistance and thermal shock re-sistance could effectively protect C/C composites from oxidation at 1773 K for 57 h in air and endure the thermal cycle between 1773 K and room temperature for 12 times,whereas the corresponding weight loss is only 1.47%.The excellent oxidation protective ability of the SiC-Si-ZrSiO4 coating could be attributed to the C/SiC gradient inner layer and the multiphase microstructure of the coating.

  20. Structure of Si-capped Ge/SiC/Si (001) epitaxial nanodots: Implications for quantum dot patterning

    Energy Technology Data Exchange (ETDEWEB)

    Petz, C. W.; Floro, J. A. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Yang, D.; Levy, J. [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States)

    2012-04-02

    Artificially ordered quantum dot (QD) arrays, where confined carriers can interact via direct exchange coupling, may create unique functionalities such as cluster qubits and spintronic bandgap systems. Development of such arrays for quantum computing requires fine control over QD size and spatial arrangement on the sub-35 nm length scale. We employ electron-beam irradiation to locally decompose ambient hydrocarbons onto a bare Si (001) surface. These carbonaceous patterns are annealed in ultra-high vacuum (UHV), forming ordered arrays of nanoscale SiC precipitates that have been suggested to template subsequent epitaxial Ge growth to form ordered QD arrays. We show that 3C-SiC nanodots form, in cube-on-cube epitaxial registry with the Si substrate. The SiC nanodots are fully relaxed by misfit dislocations and exhibit small lattice rotations with respect to the substrate. Ge overgrowth at elevated deposition temperatures, followed by Si capping, results in expulsion of the Ge from SiC template sites due to the large chemical and lattice mismatch between Ge and C. Maintaining an epitaxial, low-defectivity Si matrix around the quantum dots is important for creating reproducible electronic and spintronic coupling of states localized at the QDs.

  1. Sr–Al–Si co-segregated regions in eutectic Si phase of Sr-modified Al–10Si alloy

    International Nuclear Information System (INIS)

    The addition of 200 ppm strontium to an Al–10 wt% Si casting alloy changes the morphology of the eutectic silicon phase from coarse plate-like to fine fibrous networks. In order to clarify this modification mechanism the location of Sr within the eutectic Si phase has been investigated by a combination of high-resolution methods. Whereas three-dimensional atom probe tomography allows us to visualise the distribution of Sr on the atomic scale and to analyse its local enrichment, transmission electron microscopy yields information about the crystallographic nature of segregated regions. Segregations with two kinds of morphologies were found at the intersections of Si twin lamellae: Sr–Al–Si co-segregations of rod-like morphology and Al-rich regions of spherical morphology. Both are responsible for the formation of a high density of multiple twins and promote the anisotropic growth of the eutectic Si phase in specific crystallographic directions during solidification. The experimental findings are related to the previously postulated mechanism of “impurity induced twinning”. - Highlights: ► Eutectic microstructure of a Sr-modified Al–10Si alloy was studied by high resolution methods. ► Nano-sized Sr–Al- and Al-enriched regions within the eutectic Si phase have been found ► Sr–Al- and Al-enriched regions are located at the intersections of Si twin lamellae. ► The findings are related to the postulated modification mechanism of impurity induced twinning

  2. Sr–Al–Si co-segregated regions in eutectic Si phase of Sr-modified Al–10Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Timpel, M., E-mail: melanie.timpel@helmholtz-berlin.de [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Wanderka, N. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Schlesiger, R. [Institute of Materials Physics, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster (Germany); Yamamoto, T. [HVEM Laboratory, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395 (Japan); Isheim, D. [Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL 60208-3108 (United States); Schmitz, G. [Institute of Materials Physics, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster (Germany); Matsumura, S. [HVEM Laboratory, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395 (Japan); Banhart, J. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany)

    2013-09-15

    The addition of 200 ppm strontium to an Al–10 wt% Si casting alloy changes the morphology of the eutectic silicon phase from coarse plate-like to fine fibrous networks. In order to clarify this modification mechanism the location of Sr within the eutectic Si phase has been investigated by a combination of high-resolution methods. Whereas three-dimensional atom probe tomography allows us to visualise the distribution of Sr on the atomic scale and to analyse its local enrichment, transmission electron microscopy yields information about the crystallographic nature of segregated regions. Segregations with two kinds of morphologies were found at the intersections of Si twin lamellae: Sr–Al–Si co-segregations of rod-like morphology and Al-rich regions of spherical morphology. Both are responsible for the formation of a high density of multiple twins and promote the anisotropic growth of the eutectic Si phase in specific crystallographic directions during solidification. The experimental findings are related to the previously postulated mechanism of “impurity induced twinning”. - Highlights: ► Eutectic microstructure of a Sr-modified Al–10Si alloy was studied by high resolution methods. ► Nano-sized Sr–Al- and Al-enriched regions within the eutectic Si phase have been found ► Sr–Al- and Al-enriched regions are located at the intersections of Si twin lamellae. ► The findings are related to the postulated modification mechanism of impurity induced twinning.

  3. Steady state creep behavior of two ceramic composites SiCf-SiC and SiCf -MLAS

    OpenAIRE

    Kervadec, D.; Abbe, F.; Chermant, J.-L.

    1993-01-01

    Creep were performed by three-point bending under vacuum on SICf -SiC and SiCf-MLAS composites. The results are compared and discussed according to criteria based on the values of both temperature and stress and on the damaging features observed.

  4. Entre Dios y los hombres: la sexualidad femenina

    OpenAIRE

    Saavedra Ballesteros, Blanca Lida

    2006-01-01

    Entre dios y los hombres: la sexualidad femenina, nos aproximará a la realidad discursiva que sobre la sexualidad femenina tienen las mujeres católicas - perfil obtenido por un estudio de casos basado en grupos de oración - . Se hará relevante, entonces, la influencia que ejerce en ellas el discurso de la Iglesia Católica respecto al tema, a la vez que se notarán, igualmente, las filtraciones que, poco a poco, provocan los discursos de las feministas y teólogas feministas latinoamericanas. As...

  5. Entre ‘terminator’ y ‘frankencell

    OpenAIRE

    García Olmedo, Francisco

    1999-01-01

    Una sola palabra bien buscada puede ser más eficaz que cien argumentos cuando se trata de desacreditar cualquier idea o iniciativa, del mismo modo que las caricaturas guiñolescas están haciendo estragos entre nuestros personajes públicos. Así es el caso del apelativo "terminator", que ha sido elegido con indudable ingenio por los enemigos de una particular receta fitogenética cuyos autores son científicos del Ministerio de Agricultura de Estados Unidos y de la empresa Delta & Pine Land Compan...

  6. Sobre la relación de preferencias entre argumentos

    OpenAIRE

    Cecchi, Laura; Simari, Guillermo Ricardo

    2002-01-01

    Los diferentes modelos de sistemas argumentativos son formalismos de representación y razonamiento no monotónico que permiten caracterizar una de los principales habilidades de la inteligencia humana: la argumentación. Al definir un framework argumentativo se exige un criterio de preferencia entre argumentos, sin restringir la relación que formaliza su comportamiento. Esto motivó el estudio dicha relación, desde el punto de vista matemático, a fin de caracterizarla. El propósito de este...

  7. Relaciones entre trastornos del lenguaje y competencia socioemocional

    OpenAIRE

    Colomer Diago, Carla; Roselló Miranda, Belén; Baixauli-Fortea, Inmaculada

    2015-01-01

    Introducción. Existe una comorbilidad elevada entre los trastornos del lenguaje y los problemas conductuales, emocionales y sociales. Objetivo. Revisar la bibliografía existente sobre las dificultades sociales y emocionales de los niños con trastorno específico del lenguaje desde una perspectiva evolutiva. Desarrollo. En la infancia temprana, los resultados acerca de este tipo de dificultades en niños con un retraso del lenguaje no son concluyentes. Sin embargo, desde el período d...

  8. Relación entre diabetes mellitus y enfermedad periodontal

    Directory of Open Access Journals (Sweden)

    A.B. Navarro Sánchez

    2002-04-01

    Full Text Available La asociación entre diabetes mellitus y la enfermedad periodontal ha sido motivo de estudio durante mucho tiempo. Son varias las hipótesis que se barajan a la hora de explicar dicha relación. El propósito de este artículo es revisar los estudios publicados en la literatura periodontal hasta la fecha.The association between diabetes mellitus und Periodontal. Disease have been studied for a long time. There are several hypothesis which have tried to explain this relation. The purpose of this paper is to review the Periodontal literature up to day.

  9. Oniromancia y perspectiva entre los ette del norte de colombia

    OpenAIRE

    Juan Camilo Niño Vargas

    2009-01-01

    En algunas sociedades la interpretación onírica se considera una labor lógi- ca y significativa. La explicación de este hecho se encuentra en la forma en que el mundo ha sido construido socialmente. El presente artículo se interesa por la particular articulación de estas ideas entre los ette, una sociedad indígena del norte de Colombia que le ha otorgado al fenóme- no del sueño un lugar central dentro de la vida diaria. Para este efecto, ...

  10. ACEITAÇÃO DO "IOGURTE" DE SOJA ENTRE ADOLESCENTES

    Directory of Open Access Journals (Sweden)

    Fernanda Lopes KINOUCHI

    2009-07-01

    Full Text Available

    Os alimentos à base de soja ainda sofrem resistência ao consumo, por causa de seu sabor tido como desagradàvel. O processo da fermentação do extrato hidrossolúvel da soja contribui para a melhoria das características sensoriais, podendo ser melhorado ainda mais com a adição de aromatizantes naturais. Nos últimos anos, a soja vem sendo muito estudada, em razão de seu potencial na prevenção e no tratamento de doenças crônicas. Pesquisas têm mostrado que as isoflavonas, substâncias químicas abundantes nessa leguminosa, inibem a proliferação das células e diminuem o LDL colesterol, atributos relevantes na prevenção e no tratamento de câncer e de doenças cardiovasculares. A aceitação do "iogurte" de soja, entre adolescontes, é de fundamental importância para a divulgação e o incentivo ao consumo de produtos derivados de soja, com vistas aos possíveis benefícios futuros à saúde da população. Com o objetivo de verificar a aceitação dos "iogurtes" de soja sabores pêssego e morango entre adolescentes de escola pública e particular do município de Araraquara, foi realizado um teste de aceitação com oitenta estudantes do ensino médio, sendo quarenta de escola pública e quarenta de escola particular, com idade entre 14 e 17 anos. Os resultados revelaram que não houve diferença significativa entre as médias de aceitação do grupo de estudante da escola pública e da escola particular para as amostras do "iogurte" de soja sabores pêssego e morango. Além disso, esses resultados dão suporte a uma eventual inclusão do "iogurte" de soja na alimentação de adolescentes, o que poderia representar uma contribuição significativa para a prevenção do doenças da vida adulta.

  11. Discapacidad y trabajo. El otro entre discursos y hechos

    OpenAIRE

    Míguez, María Noel; Gómez, Ana Paula; Pinato, Cristian

    2015-01-01

    El objetivo de la presente investigación apunta a deconstruir los conceptos de normalidad e igualdad en el entramado de contingencias que se materializan en la temática de la discapacidad con relación al trabajo como categoría ontológica que media al ser. Así, se intenta dar cuenta de la ideología de la normalidad y los discursos de igualdad en la relación discapacidad-trabajo a través de un análisis correlativo entre Uruguay y Francia.

  12. Risco ocupacional de adquirir tuberculose entre trabalhadores de enfermagem hospitalar

    OpenAIRE

    2001-01-01

    Nos hospitais, os indivíduos tuberculosos são atendidos por vários profissionais e dentre eles os trabalhadores de enfermagem. Esses trabalhadores estão sujeitos a riscos de infecção tuberculosa. O estudo objetivou: levantar o número de trabalhadores de enfermagem do hospital que adquiriram tuberculose, e as características gerais em um período pré determinado; levantar a morbidade dessa doença e discutir o risco ocupacional entre estes trabalhadores. Em um ano os trabalhadores apresentaram r...

  13. Prevalência de hiperidrose entre estudantes de medicina

    Directory of Open Access Journals (Sweden)

    Fernando Luiz Westphal

    2011-12-01

    Full Text Available OBJETIVO: Identificar a prevalência de hiperidrose entre os estudantes de Medicina de Manaus/AM. MÉTODOS: Estudo observacional, transversal, do tipo inquérito que analisou a prevalência de hiperidrose primária entre os alunos de Medicina da Universidade Federal do Amazonas e sua relação com o índice de massa corporal (IMC e o stress. Os alunos foram pesados e entrevistados. Utilizou-se questionários com perguntas preconizadas pela International Hyperhidrosis Society, para relacionar a hiperidrose com as atividades diárias de cada pessoa. A análise dos resultados se deu com o cálculo da razão de prevalências e do intervalo de confiança. RESULTADOS: Entre os 293 estudantes analisados, verificou-se que um total de 16 (5,5% estudantes apresentavam sudorese excessiva dificilmente tolerável ou intolerável, interferindo em suas atividades diárias. Nenhum apresentava causas conhecidas de hiperidrose e 50% possuíam história familiar. Em todos o acometimento foi bilateral, sendo os locais mais afetados: mãos (35,7%, pés (21,4%, axila (17,9, rosto (10,7%, costas (7,1%, tórax (3,6% e abdome (3,6%. Não houve predomínio em relação ao sexo, idade ou IMC. Encontrou-se relação positiva com o IMC evidenciando sobrepeso e obesidade, sendo observado uma razão de prevalências de 2,48 superior em relação aos estudantes com peso normal ou abaixo do peso. CONCLUSÃO: A prevalência de hiperidrose primária entre os estudantes de Medicina de Manaus/AM foi de 5,5%, existindo uma relação positiva não estatística com o sobrepeso e a obesidade. Foi constatada ainda uma relação observacional com o stress.

  14. Relaciones entre autoestima y estresores percibidos en estudiantes universitarios

    OpenAIRE

    Cabanach, Ramón G.; Antonio Souto Gestal; Carlos Freire Rodríguez; María del Mar Ferradás Canedo

    2014-01-01

    Siguiendo la línea de los trabajos que inciden en el papel de los recursos personales como factores de protección frente al estrés, la presente investigación pretende analizar la relación entre la autoestima y la percepción de estresores académicos en el contexto universitario. En concreto, analizamos en qué medida los niveles de autoestima (alto, medio y bajo) influyen diferencialmente en el grado en que el estudiante valora como amenazantes diversas circunstancias propias del día a día acad...

  15. Psiconeuroinmunologia: relaciones entre factores psicologicos e inmunitarios en humanos

    OpenAIRE

    Vera Villarroel, Pablo E.; Gualberto Buela Casal

    1999-01-01

    La Psiconeuroinmunología (PNI) es un campo que estudia las relaciones bidireccionales entre la conducta, el cerebro y el sistema inmune. Desde los estudios iniciales de inmunodepresión e inmunoactivación condicionada realizadaen animales se han llevado acabo una gran cantidad de estudios en humanos, intentando verificar hasta qué punto el sistema inmune está sujeto a las influencias psicosociales. El presente artículo revisa algunos avances en esta área centrándose exclusiva...

  16. Consumo de bebidas alcohólicas entre deficientes visuales.

    OpenAIRE

    Freitas da Silva, G.R.; De Freitas Macêdo, K.N.

    2005-01-01

    Se sabe que el alcohol es una de las drogas más conocidas y usadas, siendo quizá la de mayor popularidad junto al tabaco, a pesar de muchas veces no ser reconocida como tal, por convertirse en un elemento de fácil obtención y estar asociado a la vida cultural y social de las personas. Se trazó un perfil entre deficientes visuales que consumen bebidas alcohólicas. Basándose en una investigación anterior en la se realizaron Consultas de Enfermería a 22 deficientes visuales e...

  17. La cuestión del maltrato entre escolares

    OpenAIRE

    Paladino, Celia Elba; Gorostiaga, Damián

    2010-01-01

    El maltrato entre compañeros o bullying se expresa por intermedio de comportamientos directos, por ejemplo, molestar, hostigar, amenazar, forzar, golpear o robar, que son provocados por uno o más participantes en contra de una víctima. Además de los ataques directos, la intimidación puede ser más sutil: De acuerdo a diversos estudios realizados mientras que los varones se involucran típicamente en los métodos más directos de intimidación, las chicas utilizan métodos más indirectos y sutiles, ...

  18. Empresas excelentes entre las certificadas en las normas ISO 9000

    OpenAIRE

    Climent Serrano, Salvador

    2005-01-01

    En este trabajo se realiza un estudio entre las empresas certificadas en la norma ISO 9000 de la Comunidad Valenciana mediante una encuesta, con el objetivo de diferenciar los resultados sobre incremento de competitividad por la certificación en las normas ISO 9000, dependiendo de la involucración de las empresas en los sistemas de gestión de la calidad total, así como averiguar que factores inciden para que las empresas certificadas se impliquen en mayor medida en estos sistemas

  19. Comportamientos violentos entre pares: estrategias de prevención

    OpenAIRE

    Salas, Marta A.; Carreras, Julia A.; Casacci, María Elena; Garcia, Alicia; Hogas, Alejandro; Medina, Daniel

    2007-01-01

    En este trabajo se articulan dos proyectos de investigaciones llevados a cabo el primero investigó la incidencia en la subjetividad de la manera en que el adulto naturaliza las múltiples y variadas formas de castigo en la familia; el segundo y actual, investiga las manifestaciones de los comportamientos violentos en los niños, y las representaciones sociales de la violencia Objetivos: Identificar a los fines de su prevención las principales manifestaciones e interacciones violentas entre pare...

  20. La controversia entre homosexualidad y familia : el caso cubano

    OpenAIRE

    ROBLEDO DÍAZ, LUIS

    2004-01-01

    El presente artículo constituye un resumen de la tesis Homosexualidad y familia: acoso y simetrías que el autor presentara para obtener el título de máster en Sociología por la Universidad Autónoma de Barcelona y la Universidad de La Habana. En la misma nos propusimos caracterizar algunos aspectos de la relación entre homosexualidad y familia en el contexto cubano. Para ello, nos centramos en describir los aspectos relativos a la «vida gay» en Ciudad de La Habana y en determinar el vínculo es...

  1. Formation of Si/SiC multilayers by low-energy ion implantation and thermal annealing

    NARCIS (Netherlands)

    Dobrovolskiy, S.; Yakshin, A. E.; Tichelaar, F. D.; Verhoeven, J.; E. Louis,; F. Bijkerk,

    2010-01-01

    Si/SiC multilayer systems for XUV reflection optics with a periodicity of 10-20 nm were produced by sequential deposition of Si and implantation of 1 key CHx+ ions. Only about 3% of the implanted carbon was transferred into the SIC, with a thin, 0.5-1 nm, buried SIC layer being formed. We investigat

  2. Scanning capacitance microscope study of a SiO2/Si interface modified by charge injection

    Science.gov (United States)

    Tomiye, H.; Yao, T.

    We have investigated the local electrical properties of an SiO2/Si structure using a scanning capacitance microscope (SCaM) combined with an atomic force and a scanning tunneling microscope (AFM and STM). The electrical properties of the Si substrate and the SiO2/Si interface vary with position. In this experiment we have injected charge into the SiO2 and investigated the nature of charge storage at the SiO2/Si interface. We have used the combined microscope to apply a pulse to the SiO2/Si sample, causing charge to be trapped in the SiO2/Si interface. We could clearly detect the local variation of interface charge in a non-destructive manner using the SCaM and simultaneously by capacitance-voltage (C-V) characterization. The volume of the C-V curve shift along the voltage axis due to trapped charges is dependent upon the density of the trapped charges. In doing this experiment we show one of the many possible applications of the combined SCaM/AFM/STM.

  3. Enhanced electroluminescence from nanocrystallite Si based MOSLED by interfacial Si nanopyramids

    Institute of Scientific and Technical Information of China (English)

    Gong-Ru Lin

    2007-01-01

    The interfacial Si nano-pyramid-enhanced electroluminescence (EL) of an ITO/SiOx/p-Si/Al metal-oxidesemiconductor (MOS) diode with turn-on voltage of 50 V, threshold current of 1.23 mA/cm2, output power of 16 nW, and lifetime of 10 h is reported.

  4. About the International System of Units (SI) Part III. SI Table

    Science.gov (United States)

    Aubrecht, Gordon J., II; French, Anthony P.; Iona, Mario

    2012-01-01

    Before discussing more details of SI, we will summarize the essentials in a few tables that can serve as ready references. If a unit isn't listed in Tables I-IV, it is not part of SI or specifically allowed for use with SI. The units and symbols that are sufficient for most everyday applications are given in bold.

  5. The effect of biaxial strain on impurity diffusion in Si and SiGe

    DEFF Research Database (Denmark)

    Larsen, Arne Nylandsted; Zangenberg, Nikolaj; Fage-Pedersen, Jacob

    2005-01-01

    Results from diffusion studies of different impurities in biaxially strained Si and Si"1"-"xGe"x for low x-values will be presented. The structures are all molecular-beam epitaxy (MBE) grown on strain-relaxed Si"1"-"xGe"x layers, and the impurity profiles are introduced during growth. We have...

  6. Polycrystalline SiC as source material for the growth of fluorescent SiC layers

    DEFF Research Database (Denmark)

    Kaiser, M.; Hupfer, T.; Jokubavicus, V.;

    2013-01-01

    Polycrystalline doped SiC act as source for fluorescent SiC. We have studied the growth of individual grains with different polytypes in the source material. We show an evolution and orientation of grains of different polytypes in polycrystalline SiC ingots grown by the Physical Vapor Transport...

  7. Further Developments in Modeling Creep Effects Within Structural SiC/SiC Components

    Science.gov (United States)

    Lang, Jerry; DiCarlo, James A.

    2008-01-01

    Anticipating the implementation of advanced SiC/SiC composites into turbine section components of future aero-propulsion engines, the primary objective of this on-going study is to develop physics-based analytical and finite-element modeling tools to predict the effects of constituent creep on SiC/SiC component service life. A second objective is to understand how to possibly manipulate constituent materials and processes in order to minimize these effects. Focusing on SiC/SiC components experiencing through-thickness stress gradients (e.g., airfoil leading edge), prior NASA creep modeling studies showed that detrimental residual stress effects can develop globally within the component walls which can increase the risk of matrix cracking. These studies assumed that the SiC/SiC composites behaved as isotropic viscoelastic continuum materials with creep behavior that was linear and symmetric with stress and that the creep parameters could be obtained from creep data as experimentally measured in-plane in the fiber direction of advanced thin-walled 2D SiC/SiC panels. The present study expands on those prior efforts by including constituent behavior with non-linear stress dependencies in order to predict such key creep-related SiC/SiC properties as time-dependent matrix stress, constituent creep and content effects on composite creep rates and rupture times, and stresses on fiber and matrix during and after creep.

  8. Preparation of Si3N4–SiC composites by microwave route

    Indian Academy of Sciences (India)

    M Panneerselvam; K J Rao

    2002-12-01

    Si3N4–SiC composites have been microwave sintered using -Si3N4 and -SiC as starting materials. Si3N4 rich compositions (95 and 90 vol.% Si3N4) have been sintered above 96% of theoretical density without using any sintering additives in 40 min. A monotonic decrease in relative density is observed with increase in SiC proportion in the composite. Decrease in relative density has manifested in the reduction of fracture toughness and microhardness values of the composite with increase in SiC content although the good sintering of matrix Si3N4 limits the decrease of fracture toughness. Highest value of fracture toughness of 6.1 MPa m1/2 is observed in 10 vol.% SiC composite. Crack propagation appears to be transgranular in the Si3N4 matrix and the toughening of the composites is through crack deflection around hard SiC particles in addition to its debonding from the matrix.

  9. siRNAmod: A database of experimentally validated chemically modified siRNAs.

    Science.gov (United States)

    Dar, Showkat Ahmad; Thakur, Anamika; Qureshi, Abid; Kumar, Manoj

    2016-01-01

    Small interfering RNA (siRNA) technology has vast potential for functional genomics and development of therapeutics. However, it faces many obstacles predominantly instability of siRNAs due to nuclease digestion and subsequently biologically short half-life. Chemical modifications in siRNAs provide means to overcome these shortcomings and improve their stability and potency. Despite enormous utility bioinformatics resource of these chemically modified siRNAs (cm-siRNAs) is lacking. Therefore, we have developed siRNAmod, a specialized databank for chemically modified siRNAs. Currently, our repository contains a total of 4894 chemically modified-siRNA sequences, comprising 128 unique chemical modifications on different positions with various permutations and combinations. It incorporates important information on siRNA sequence, chemical modification, their number and respective position, structure, simplified molecular input line entry system canonical (SMILES), efficacy of modified siRNA, target gene, cell line, experimental methods, reference etc. It is developed and hosted using Linux Apache MySQL PHP (LAMP) software bundle. Standard user-friendly browse, search facility and analysis tools are also integrated. It would assist in understanding the effect of chemical modifications and further development of stable and efficacious siRNAs for research as well as therapeutics. siRNAmod is freely available at: http://crdd.osdd.net/servers/sirnamod. PMID:26818131

  10. Advances in SiC/SiC Composites for Aero-Propulsion

    Science.gov (United States)

    DiCarlo, James A.

    2013-01-01

    In the last decade, considerable progress has been made in the development and application of ceramic matrix composites consisting of silicon carbide (SiC) based matrices reinforced by small-diameter continuous-length SiC-based fibers. For example, these SiC/SiC composites are now in the early stages of implementation into hot-section components of civil aero-propulsion gas turbine engines, where in comparison to current metallic components they offer multiple advantages due to their lighter weight and higher temperature structural capability. For current production-ready SiC/SiC, this temperature capability for long time structural applications is 1250 degC, which is better than 1100 degC for the best metallic superalloys. Foreseeing that even higher structural reliability and temperature capability would continue to increase the advantages of SiC/SiC composites, progress in recent years has also been made at NASA toward improving the properties of SiC/SiC composites by optimizing the various constituent materials and geometries within composite microstructures. The primary objective of this chapter is to detail this latter progress, both fundamentally and practically, with particular emphasis on recent advancements in the materials and processes for the fiber, fiber coating, fiber architecture, and matrix, and in the design methods for incorporating these constituents into SiC/SiC microstructures with improved thermo-structural performance.

  11. Microstructure and abrasive wear studies of laser clad Al-Si/SiC composite coatings

    NARCIS (Netherlands)

    Anandkumar, R.; Colaco, R.; Ocelik, V.; De Hosson, J. Th. M.; Vilar, R.; Gyulai, J; Szabo, PJ

    2007-01-01

    Surface coatings of Al-Si/SiC metal-matrix composites were deposited on Al-7 wt. % Si alloy substrates by laser cladding. The microstructure of the coatings was characterized by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The microstructure of the coating mate

  12. Relación entre la ingesta de sal y la presión arterial en pacientes hipertensos

    Directory of Open Access Journals (Sweden)

    Lucía Navas Santos

    2016-03-01

    Full Text Available Introducción: La hipertensión arterial resistente o refractaria al tratamiento supone un serio problema de salud pública y aunque, no están claros los mecanismos por los que se produce esta resistencia, se sospecha que el consumo de sodio puede jugar un papel importante en el mantenimiento de la misma. Objetivo: Determinar si los pacientes con hipertensión resistente toman sodio oculto en los alimentos ingeridos en su dieta; así como relacionar este consumo con sus hábitos dietéticos. Pacientes y Métodos: Se estudiaron 32 pacientes con una media de edad de 74,25±6,38 años, (65,6% hombres y 34,4% mujeres. Se realizó un estudio descriptivo y transversal mediante entrevista estructurada sobre consumo de alimentos. Se estudió: edad, género, estado civil, presión arterial, responsable de la elaboración de las comidas, índice de masa corporal (IMC, consumo de sodio oculto en la dieta y percepción de los pacientes sobre su consumo de sodio. Resultados: Se encontró una ingesta media real de 3693,56±2330,97 mg de sodio. En el 59,4% de los casos las comidas las elaboraba otra persona diferente al paciente, siendo mayor el consumo de sodio en estos pacientes (3.709,44±529,37 frente a 3.677,69±649,27 mg. Respecto a la percepción sobre la cantidad de sodio ingerida, el 9,4% decían no tomar nada, el 56,3% poco, el 21,9% lo normal y el 12,5% bastante. Los que decían no tomar nada de sodio y lo normal, el mayor aporte lo hacían durante la cena; y los que decían tomar poco sodio y bastante, era en el almuerzo. Se encontró correlación significativa entre ingesta de sodio total e IMC (r=0,411, p & lt0,05. No se encontró relación entre consumo de sodio y hipertensión arterial. Conclusiones: Al menos en la muestra estudiada, no existe relación entre ingesta de sodio y presión arterial; existe una relación directa entre consumo de sodio y la persona que cocina. Por otro lado, la percepción que tienen estos pacientes respecto a su

  13. Effect of Nano-SiC Particles on the Performance and Microstructure of Si3N4/SiC Composite Ceramics%纳米SiC对Si3N4/SiC复相陶瓷性能及显微结构的影响

    Institute of Scientific and Technical Information of China (English)

    张伟儒; 李勇; 陈文

    2007-01-01

    In this paper, Si3 N4/SiC composite ceramics were prepared from two different raw materials with nano-SiC particles or organic precursor. Effect of nano-SiC particles on the performance and microstructure of the Si3 N4/SiC ceramics was studied, and the relation between reinforced mechanism and microstructure of materials was also investigated.%本研究通过采用纳米SiC粉体及有机前驱体两种途径,制备了Si3N4/SiC粒子(Si3 N4/纳米SiC)复相陶瓷,研究了纳米SiC对Si3 N4/SiC复相陶瓷性能及显微结构的影响,讨论了材料强化的机制与显微结构的关系.

  14. Quantitative détermination of aluminium and silicon in SiO2 and Al2O3 by X ray fluorescence

    Directory of Open Access Journals (Sweden)

    Sagrera, José Luis

    1966-09-01

    Full Text Available Not availableEn el presente trabajo, se describe la influencia de estos dos elementos entre si cuando se determinan sus contenidos en muestras binarias de Si02 y Al203. por fluorescencia de rayos X. En este mismo artículo se explica la corrección de estas influencias utilizando una fusión con tetraborato sódico, así como el procedimiento práctico para realizarla. Se detalla el procedimiento mediante fotografías tomadas en los momentos más interesantes del proceso de fusión.

  15. Thermochemical instability effects in SiC-based fibers and SiC{sub f}/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, G.E.; Henager, C.H.; Jones, R.H. [Pacific Northwest National Laboratory, Richland, WA (United States)

    1997-08-01

    Thermochemical instability in irradiated SiC-based fibers with an amorphous silicon oxycarbide phase leads to shrinkage and mass loss. SiC{sub f}/SiC composites made with these fibers also exhibit mass loss as well as severe mechanical property degradation when irradiated at 800{degrees}C, a temperature much below the generally accepted 1100{degrees}C threshold for thermomechanical degradation alone. The mass loss is due to an internal oxidation mechanism within these fibers which likely degrades the carbon interphase as well as the fibers in SiC{sub f}/SiC composites even in so-called {open_quotes}inert{close_quotes} gas environments. Furthermore, the mechanism must be accelerated by the irradiation environment.

  16. Silane photoabsorption spectra near the Si 2p thresholds: the geometry of Si 2p excited SiH4

    Institute of Scientific and Technical Information of China (English)

    张卫华; 许如清; 李家明

    2003-01-01

    Based on the multiple-scattering self-consistent-field method, we have studied the photoabsorption spectra near the Si 2p thresholds of silane. According to our calculations, the clear assignments of the inner-shell photoabsorption spectra are provided. In comparison with the high-resolution experimental spectra, the geometric structure of the Si 2p-excited SiH4** is recommended to be of a C2v symmetry. More specifically, the Si 2p-excited Si4** have two bond lengths of 2.50 a.u. and another two bond lengths of 2.77 a.u., and the corresponding two bond angles are 104.0° and 112.5° respectively.

  17. Relação entre o craving por tabaco e o craving por crack em pacientes internados para desintoxicação

    Directory of Open Access Journals (Sweden)

    Taís Cardoso de Zeni

    2011-01-01

    Full Text Available OBJETIVO: Verificar se há relação entre aumento do craving por crack e aumento do craving por tabaco em pacientes internados para desintoxicação. MÉTODO: Ensaio clínico tipo quase-experimental de análise quantitativa. Amostra composta por 32 homens dependentes de cocaína (crack e tabaco, em duas a três semanas de abstinência. Realizou-se intervenção em grupo, no qual, inicialmente, foram aplicados: CCQB (Cocaine Craving Questionnaire-Brief , QSUB (Questionnaire of Smoking Urges-Brief e BAI (Inventário Beck de Ansiedade. Em seguida, foram aplicadas imagens relacionadas ao crack e reaplicados CCQB, QSUB e BAI. Após, foi realizada entrevista individual em que se aplicaram FSD (Ficha com Dados Sociodemográficos e FTND (Fagerström Test for Nicotine Dependence. RESULTADOS: A partir da exposição de imagens relativas ao crack, houve aumento significativo do craving por crack, do craving por tabaco e dos sintomas de ansiedade, estando essas medidas correlacionadas positivamente entre si. CONCLUSÃO: Os resultados indicam uma associação significativa entre craving por crack e craving por tabaco, sugerindo que a abstinência de tabaco pode ajudar na eficácia do tratamento para dependência de crack.

  18. Relación entre la potencia muscular de extremidades inferiores y tronco con la velocidad de salida de la bola en el swing de drive en golf

    Directory of Open Access Journals (Sweden)

    Lorena Torres Ronda

    2010-09-01

    Full Text Available A pesar del interés emergente en el acondicionamiento físico en el golf, se han llevado a cabo pocos estudios para valorar la relación entre la potencia mecánica y el rendimiento en golf. El objetivo de este estudio fue valorar si existía una correlación entre la velocidad de salida de la bola del swing de drive y la potencia muscular de extremidades inferiores y tronco, en un grupo de 8 golfistas (16,8 ± 1,4 años; 2,2 ± 1,8 Handicap; 63,1 ± 6,4 kg.; 172,7 ± 7,5 cm. El test incluyó mediciones de la velocidad de salida de la bola y tests de potencia mecánica (prensa de piernas horizontal, press de banca y rotaciones de tronco. Los resultados de este estudio indican que existe una correlación significativa entre la velocidad de salida de la bola y la potencia piernas (prensa de piernas horizontal: r2=,933; p=,000 y del tronco (press de banca: r2 = 0,66; p = ,014. La prensa de piernas se mostró como el predictor más representativo para la velocidad de salida de la bola (r2 = 0,934; p = ,000.

  19. Advances in wide bandgap SiC for optoelectronics

    DEFF Research Database (Denmark)

    Ou, Haiyan; Ou, Yiyu; Argyraki, Aikaterini;

    2014-01-01

    . This paper will review the advances in fluorescent SiC for white light-emitting diodes, covering the poly-crystalline doped SiC source material growth, single crystalline epitaxy growth of fluorescent SiC, and nanofabrication of SiC to enhance the extraction efficiency for fluorescent SiC based white LEDs....

  20. Monolithic integration of Si-MOSFET and GaN-LED using Si/SiO2/GaN-LED wafer

    Science.gov (United States)

    Tsuchiyama, Kazuaki; Yamane, Keisuke; Utsunomiya, Shu; Sekiguchi, Hiroto; Okada, Hiroshi; Wakahara, Akihiro

    2016-10-01

    In this report, we present a monolithic integration method for a Si-MOSFET and a GaN-LED onto a Si/SiO2/GaN-LED wafer as an elemental technology for monolithic optoelectronic integrated circuits. To enable a Si-MOSFET device process, we investigated the thermal tolerance of a thin top-Si and GaN-LED layer on a Si/SiO2/GaN-LED wafer. The high thermal tolerance of the Si/SiO2/GaN-LED structure allowed for the monolithic integration of a Si n-MOSFET and a GaN-µLED without degrading the performance of either device. A GaN-µLED driver circuit was fabricated using a Si n-MOSFET and a µLED of 30 × 30 µm2, with the modulation bandwidth of the circuit estimated to be over 10 MHz.

  1. Synthesis of Hybrid SiC/SiO2 Nanoparticles and Their Polymer Nanocomposites

    Science.gov (United States)

    Hassan, Tarig A.; Rangari, Vijaya K.; Baker, Fredric; Jeelani, Shaik

    2013-04-01

    In the present investigation, silicon carbide (β-SiC) nanoparticles ( 30 nm) were coated on silicon dioxide (SiO2) nanoparticles ( 200 nm) using sonochemical method. The resultant hybrid nanoparticles were then infused into SC-15 epoxy resin to enhance the thermal and mechanical properties of SC-15 epoxy for structural application. To fabricate an epoxy-based nanocomposite containing SiC/SiO2 hybrid nanoparticles, we have opted a two-step process. In the first step, the silica nanoparticles were coated with SiC nanoparticles using high intensity ultrasonic irradiation. In a second step, 1 wt.% of as-prepared SiC/SiO2 particles were dispersed in epoxy part-A (diglycidylether of bisphenol A) using a high intensity ultrasound for 30 min at 5°C. The part-B (cycloaliphatic amine hardener) of the epoxy was then mixed with part-A-SiC/SiO2 mixture using a high-speed mechanical stirrer for 10 min. The SiC/SiO2/epoxy resin mixture was cured at room temperature for 24 h. The SiC nanoparticles coating on SiO2 was characterized using X-ray diffraction (XRD) and high resolution transmission electron microscope (TEM). The as-prepared nanocomposite samples were characterized using thermo gravimetric analysis (TGA) and differential scanning calorimeter (DSC). Compression tests have been carried out for both nanocomposite and neat epoxy systems. The results indicated that 1 wt.% (SiC) + (SiO2) loading derived improvements in both thermal and mechanical properties when compared to the neat epoxy system.

  2. Modification of Mg{sub 2}Si in Mg–Si alloys with gadolinium

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Lingying; Hu, Jilong, E-mail: hjlong@csu.edu.cn; Tang, Changping; Zhang, Xinming; Deng, Yunlai; Liu, Zhaoyang; Zhou, Zhile

    2013-05-15

    The modification effect of gadolinium (Gd) on Mg{sub 2}Si in the hypereutectic Mg–3 wt.% Si alloy has been investigated using optical microscope, scanning electron microscope, X-ray diffraction and hardness measurements. The results indicate that the morphology of the primary Mg{sub 2}Si is changed from coarse dendrite into fine polygon with the increasing Gd content. The average size of the primary Mg{sub 2}Si significantly decreases with increasing Gd content up to 1.0 wt.%, and then slowly increases. Interestingly, when the Gd content is increased to 4.0 and 8.0 wt.%, the primary and eutectic Mg{sub 2}Si evidently decrease and even disappear. The modification and refinement of the primary Mg{sub 2}Si is mainly attributed to the poisoning effect. The GdMg{sub 2} phase in the primary Mg{sub 2}Si is obviously coarsened as the Gd content exceeds 2.0 wt.%. While the decrease and disappearance of the primary and eutectic Mg{sub 2}Si are ascribed to the formation of vast GdSi compound. Therefore, it is reasonable to conclude that proper Gd (1.0 wt.%) addition can effectively modify and refine the primary Mg{sub 2}Si. - Highlights: ► Proper Gd (1.0 wt.%) addition can effectively modify and refine the primary Mg{sub 2}Si. ► We studied the reaction feasibility between Mg and Si, Gd and Si in Mg–Gd–Si system. ► We explored the modification mechanism of Gd modifier on Mg{sub 2}Si.

  3. La Democracia en América Latina: la alternativa entre populismo y democracia deliberativa

    Directory of Open Access Journals (Sweden)

    Guariglia, Osvaldo

    2011-06-01

    Full Text Available In Politics VI 2, 1317b 1-17, Aristotle defines «democracy» as follows: «the aim of democracy is, ideally, freedom from any interference of government, and, failing that, such freedom as comes from alternation of ruling and being ruled. It contributes, in this way, to a general system of liberty based on equality». Historically, this normative model shaped two possible political regimes, v. gr., popular or extreme democracy, based on direct participation of all citizens, as in Athens, and a «mixed constitution» containing oligarchic as well as democratic features, called «republican» in the roman tradition since Cicero. Modern democracy was the heir of both these Ancient regimes, tempered by the new conception of individual rights belonging to Modern thought from Hugo Grotius to the Universal Declaration of Human Rights. The representative constitution was, thus, the modern solution to the conflict between government of the majority and government of the laws. Since their Independence in the 19th century, Latin American democracies suffer from the unresolved tension between populism and the liberal constitutional regime. The neo-populism that grew in the last years of 20th century appears as a response and defiance to democracy’s unfulfilled promises. Against defenders of authoritarian populism, such as Ch. Mouffe and E. Laclau, I argue that deliberative democracy is a better response to them.

    En Política VI 2, 1317b 1-17, Aristóteles define así la democracia: «el rasgo esencial de la democracia es el vivir como se quiere sin ninguna interferencia y de aquí vino el de no ser gobernado, si es posible por nadie, y si no, por turnos. Esta característica contribuye a un sistema general de la libertad fundada en la igualdad». Este modelo normativo dio lugar, históricamente, a dos posibles regímenes políticos, la democracia popular o extrema, basada en la participación directa de todos los

  4. Relación entre Cultura y Valores Organizacionales

    Directory of Open Access Journals (Sweden)

    Carlos Roberto Rodríguez Castellanos

    2013-01-01

    Full Text Available Las organizaciones son sistemas activos y como cualquier otro sistema, funcionan mejor cuando variables como la cultura y valores organizacionales obran en una misma dirección. Dichas variables son elementales para una organización que pretende que sus trabajadores estén cohesionados, compartan sus objetivos, estén motivados, coordinados, sean leales y más eficientes. Esta investigación tiene como finalidad identificar la cultura y valores organizacionales presentes en los trabajadores de nivel operativo de una empresa de tamaño grande, además de evaluar la relación existente entre estas dos variables. Se aplicó una encuesta en una muestra de 171 trabajadores, los resultados revelan que la cultura organizacional que predomina es la de mercado, mientras que el valor organizacional que destaca en los empleados es el de auto trascendencia. A través de la prueba de hipótesis de Ji cuadrada, se encontró una relación significativa entre la cultura y los valores organizacionales de la empresa. Esta correspondencia representa una oportunidad para conseguir un mejor desarrollo y desempeño organizacional.

  5. Prazer e sofrimento entre os trabalhadores de Call Center

    Directory of Open Access Journals (Sweden)

    Carolina Scolari

    2009-12-01

    Full Text Available Os conceitos de Taylor foram fundamentais para o desenvolvimento industrial no século XX. Ainda hoje, seus ensinamentos estão presentes em diversos ramos da economia, inclusive, no setor de call center. Call center é uma estrutura que visa ao atendimento de clientes com a utilização de um terminal de computador e de um aparelho telefônico. Esse setor sofreu grande expansão e, em 2006, foi responsável pela geração de 60 mil empregos diretos, tornando-se uma forma de contato e negócios atrativa para empresas do ramo público e privado. O objetivo deste artigo foi analisar as vivências de prazer e sofrimento no trabalho entre os operadores de call centers. Foi realizada uma pesquisa qualitativa, estratégia de estudo de caso e método de análise dos dados, análise de conteúdo. Como resultados, foram elaboradas algumas categorias finais, entre elas as mediações no trabalho, analisada no presente artigo sob o referencial teórico da psicodinâmica do trabalho.

  6. Apoio social e saúde entre idosos

    Directory of Open Access Journals (Sweden)

    Ramos Marília P.

    2002-01-01

    Full Text Available O presente artigo trata da relação entre a saúde dos idosos e relacionamentos sociais, bem como na interpretação e entendimento desta problemática sob a luz de dois enfoques teóricos: um macro, centrado na Teoria da Integração Social de Emile Durkheim e outro micro, centrado na Teoria das Trocas, de Peter Blau, com ênfase na Teoria da Eqüidade. A integração social (freqüência de contatos pode ter efeitos negativos na saúde, mas isto tem de ser medido pela qualidade dos contatos. Algumas conclusões apresentadas indicam que as relações sociais têm um efeito na saúde, no sentido de que as pessoas, nas sociedades modernas, esperam a reciprocidade, e, quando isto não é possível, principalmente na fase do envelhecimento, as pessoas sentem-se dependentes, e isso pode afetar a saúde de diferentes maneiras. Por outro lado, quando as pessoas têm problemas de saúde, elas experienciam uma falta de relações sociais balanceadas devido à incapacidade para trocar em bases iguais. Sendo assim, conclui-se que a relação entre relações sociais e saúde na população idosa pode ser uma relação recíproca.

  7. Bogotá: entre la identidad y el marketing urbano

    Directory of Open Access Journals (Sweden)

    Isabel Duque Franco

    2011-01-01

    Full Text Available Durante los últimos años, en el marco de la competitividad entre ciudades, el marketing urbano se ha convertido en un instrumento adicional de la gestión y la planificación estratégicas para responder a la necesidad de atraer inversiones, empresas y turistas. En el presente artículo se abordan, desde una perspectiva crítica, la naturaleza, los tipos y los alcances del marketing urbano. En la parte empírica, se analizan las campañas de promoción interna y externa que han llevado a cabo las diferentes administraciones de Bogotá en los últimos quince años que evidencian cierto grado de continuidad y secuencia lógica en tanto en una primera instancia le apuestan a la promoción y consolidación de una imagen de ciudad interna más o menos compartida por entidades y ciudadanos, para luego proyectarse hacia fuera, asumiendo directamente los requerimientos de la competitividad entre ciudades.

  8. A LIBERDADE EM SARTRE: UNIDADE ENTRE PROJETO E ENGAJAMENTO

    Directory of Open Access Journals (Sweden)

    Josiane Fátima Wambier

    2003-01-01

    Full Text Available O objetivo deste trabalho é refletir a liberdade em Sartre, tendo como base os textos: O existencialismo é um humanismo (1945 e Questão de método, a célebre introdução de Crítica da razão dialética (1960. A liberdade em Sartre é um tema filosófico e literário. No início do processo de sua trajetória intelectual, ela é encerrada dentro do cogito cartesiano: “penso, logo existo”. Apesar de ser concebida como uma pura subjetividade, ela também é entendida como projeto que se realiza na ação através do engajamento do homem no mundo. Posteriormente, ela é remetida para o plano histórico e relacionada com a necessidade no interior de uma tensão dialética entre objetividade e subjetividade. Mesmo nesta fase, o núcleo central do conceito sartreano de liberdade é conservado: a unidade entre projeto e engajamento.

  9. Lócus digital: um lugar entre tantos outros

    Directory of Open Access Journals (Sweden)

    Fabio B. Josgrilberg

    2012-01-01

    Full Text Available El actual periodo técnico articula relaciones sociales y objetos técnicos con una racionalidad que le es propia. Con base en las ideas de Milton Santos, Michel de Certeau y Maurice Merleau-Ponty, se pretende reflexionar acerca de la relación dialéctica entre las determinaciones técnicas y las prácticas cotidianas de los sujetos. Destacamos el concepto de locus digital como un lugar organizado por estrategias que movilizan sistemas digitales de información y comunicación, sostenidos por una infraestructura peculiar de red distribuida. En el locus digital, los ciudadanos y ciudadanas están sometidos a presiones diversas, sino también reinventan la vida, crean espacios. La reflexión sobre la relación dialéctica entre locus digital y la reinvención de espacios busca evitar tanto el relativismo en la comprensión de las prácticas cuotidianas como el determinismo tecnológico.

  10. Desarrollo convergente municipal entre estados contiguos a Nayarit y Sinaloa

    Directory of Open Access Journals (Sweden)

    Eduardo Meza-Ramos

    2010-01-01

    Full Text Available El análisis del crecimiento económico registra disparidades sectoriales que se manifiestan en el interior de los países, entre las áreas urbanas y las rurales; entre las regiones prósperas y las rezagadas. En México la política de liberalización comercial no se ha visto reflejada de manera generalizada en la riqueza de la población. Se evaluó la hipótesis de convergencia en el ámbito municipal de los estados de Chihuahua, Durango, Jalisco, Nayarit, Sinaloa, Sonora y Zacatecas; por los datos considerados en el estudio se puede argumentar la existencia de convergencia ¿ y ¿, pues en promedio, la desviación estándar en el año 1989 fue de 1.73 y disminuyó a 1.31 en 2006. La convergencia ¿ describe una relación negativa con un valor absoluto de su estadístico mayor a 2; con 95% de confianza. Cabe señalar que se cuenta con políticas sociales y sectoriales pero se carece de políticas públicas que promuevan el desarrollo regional.

  11. Bogotá: entre la identidad y el marketing urbano

    Directory of Open Access Journals (Sweden)

    Duque Franco Isabel

    2011-07-01

    Full Text Available Durante los últimos años, en el marco de la competitividad entre ciudades, el marketing urbano se ha convertido en un instrumento adicional de la gestión y la planificación estratégicas para responder a la necesidad de atraer inversiones, empresas y turistas. En el presente artículo se abordan, desde una perspectiva crítica, la naturaleza, los tipos y los alcances del marketing urbano. En la parte empírica, se analizan las campañas de promoción interna y externa que han llevado a cabo las diferentes administraciones de Bogotá en los últimos quince años que evidencian cierto grado de continuidad y secuencia lógica en tanto en una primera instancia le apuestan a la promoción y consolidación de una imagen de ciudad interna más o menos compartida por entidades y ciudadanos, para luego proyectarse hacia fuera, asumiendo directamente los requerimientos de la competitividad entre ciudades.

  12. Para ver entre las sombras: la mirada de Albert Camus

    Directory of Open Access Journals (Sweden)

    Espinosa Rubio, Luciano

    2012-12-01

    Full Text Available There are some free persons that have something like a magnetic needle, so in a dark time we need what Albert Camus offers: a living example (not a list of answers of integrity, compassion and wise judgment. He had to choose (maybe like everybody between nonsense and rebelliousness, and after between a daily attitude of fear or confidence. Finally, Camus tells us that the nature of human being and the beauty of the world must balance the historical ambitions.

    Hay algunas personas libres que tienen algo semejante a una brújula, por eso en tiempos oscuros necesitamos lo que Albert Camus ofrece: un ejemplo vivo (no una lista de respuestas de integridad, compasión y buen juicio. Tuvo que elegir (quizá como todos entre el absurdo y la rebeldía, y después entre una actitud cotidiana de miedo o confianza. Finalmente, Camus nos dice que la naturaleza del ser humano y la belleza del mundo deben equilibrar las ambiciones históricas.

  13. El comercio bilateral de cosméticos entre Argentina y Brasil en el MERCOSUR entre 2009 y 2013

    OpenAIRE

    Odorizzi, Leila Aparecida

    2016-01-01

    Esta investigación tiene como objetivo general analizar el sector industrial de cosméticos entre Brasil y Argentina. Para ello, se valió de metodología cuantitativa y análisis descriptivo, generando gráficos, cuadros y tablas capaces de representar los datos de forma dinámica. Las consideraciones finales responden a los objetivos e hipótesis de este estudio, así como a la pregunta de esta investigación, señalando que el crecimiento del sector de cosméticos alcanza un excelente rendimiento com...

  14. Interactions entre virus ou entre virus et leurs satellites chez un hote commun. II. - Interferences positives : synergie, complementation, assistance

    OpenAIRE

    MARCHOUX, Georges

    1988-01-01

    Deux ou plusieurs virus, apparentés ou non, peuvent se multiplier ensemble dans une même plante et également dans une même cellule. Les interactions entre virus qui en résultent peuvent s’exprimer sur les formes variées allant de l’antagonisme (MARCHOUX 1987) à la synergie. Dans les cas de synergie, les symptômes, la vitesse de multiplication et/ou la distribution d’un virus sont souvent augmentés en présence d’un autre virus. Des interactions structurales nucléoprotéiques, telles que mas...

  15. Alpha-Irradiation-Induced Doping of Si

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun Je; Kong, Young Bae; Hur, Min Goo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    A method to dope Si was presented on the base of the alpha irradiation. After the alpha irradiation, P atoms were created from Si atoms by nuclear transmutation while the microstructure of Si surfaces was almost unchanged. As the fluence increased, the amount of P atoms on the Si surface was also increased. It has been revealed that semiconducting materials can be doped by nuclear reactions. Those reactions can be induced by thermal neutrons, high energy charged particles and photons. Among them, researches on neutron transmutation doping have been intensively performed. Furthermore, this method has been widely used for the production of P-doped Si in semiconductor industries. However, researches on nuclear doping induced by charged particles were rarely carried out relatively.

  16. Comportamiento a la corrosión electroquímica de aleaciones MgAl con recubrimientos de materiales compuestos Al/SiCp mediante proyección térmica

    Directory of Open Access Journals (Sweden)

    Pardo, A.

    2010-04-01

    Full Text Available The corrosion protection of Mg-Al alloys by flame thermal spraying of Al/SiCp composite coatings was evaluated by electrochemical impedance spectroscopy in 3.5 wt.% NaCl solution. The volume fraction of SiC particles (SiCp varied between 5 and 30%. The as-sprayed Al/SiCp composite coatings revealed a high number of micro-channels, largely in the vicinity of the SiC particles, that facilitated the penetration of the electrolyte and the subsequent galvanic corrosion of the magnesium substrates. The application of a cold-pressing post-treatment reduced the degree of porosity of the coatings and improved the bonding at the coating/substrate and Al/SiC interfaces. This resulted in improved corrosion resistance of the coated specimens. The effectiveness of the coatings slightly decreased with the addition of 5-30 vol.% SiCp compared with the unreinforced thermal spray aluminium coatings.

    Se estudia, mediante espectroscopía de impedancia electroquímica en solución 3,5 % NaCl, la protección frente a la corrosión de aleaciones Mg-Al recubiertas por proyección térmica con materiales compuestos Al/SiCp. Se varió la fracción de volumen de las partículas de SiC (SiCp entre 5 y 30 %. Los recubrimientos efectuados por proyección térmica revelan un elevado número de microcanales, en la vecindad de las partículas de SiC, que facilitan la penetración del electrolito originando procesos de corrosión galvánica en los substratos de las aleaciones de magnesio. Un tratamiento posterior mediante la aplicación de una presión en frío reduce el grado de porosidad de los recubrimientos y mejora la unión, tanto entre el substrato y el recubrimiento como entre las partículas de aluminio y SiC, mejorando la resistencia a la corrosión de las aleaciones recubiertas. La efectividad de los recubrimientos disminuye ligeramente con la adición de SiCp cuando se comparan con los mismos recubrimientos de aluminio sin refuerzo.

  17. Entre la realidad y el deseo: Una visión del asesoramiento

    Directory of Open Access Journals (Sweden)

    Lourdes Montero

    2008-01-01

    Full Text Available Este artículo pretende destacar la importancia de aspectos como la colaboración, el trabajo en red y la dinamización de proyectos de innovación, como ejes fundamentales del asesoramiento psicopedagógico en un centro educativo. El trabajo colaborativo entre los distintos agentes implicados dentro y fuera de la institución escolar, así como la figura del asesor como dinamizador de cambios educativos orientados a la mejora, no sólo constituyen el supuesto de partida sino la meta deseada. Comenzaremos el trabajo con una necesaria aclaración de términos, dada la enorme diversidad de sentidos de los términos manejados, tratando de conceptualizar qué entendemos por asesorar y a qué tipo de asesores nos estamos refiriendo. Y si bien haremos una mención al conjunto de figuras que ocupan hoy el amplio paraguas del asesoramiento, nuestra mirada se focalizará en el asesoramiento interno en un centro educativo en el marco de la orientación. Inicialmente, partimos de reconocer el complejo entramado de perfiles y funciones de los distintos profesionales y la labor asesora de todos ellos a distintos niveles. Como hemos mencionado, nos centraremos en la figura del asesor interno (principalmente el orientador escolar y trataremos de ver cuál es su situación, tomando como punto de partida el conocimiento de cerca y desde dentro de la realidad gallega, en un rico y constante devenir de la práctica a la teoría y de ésta a la práctica. Nuestro trabajo se sitúa así en el marco de una perspectiva biográfica en la constitución del asesoramiento.

  18. Entre hybridité et univocité culturelles : aspects du multiculturalisme britannique à Bristol

    Directory of Open Access Journals (Sweden)

    Vincent Latour

    2007-11-01

    Full Text Available Cet article tentera de montrer si la Grande-Bretagne en général et son modèle multiculturel en particulier peuvent s'accommoder de l’hybridité culturelle, voire l’encourager. A contrario le multiculturalisme britannique peut-il générer, sciemment ou non, un refus de cette hybridité ? Des données qualitatives de terrain, glanées entre 2000 et 2005, à la faveur des enquêtes menées à Easton et St Paul's, deux inner cities de Bristol, sont apportées pour appuyer l’analyse. L’évolution récente de ce modèle amènera des interrogations sur son devenir, ainsi que sur l'hybridation d'autres modes de gestion de la diversité en Europe, notamment le modèle républicain français.This article attempts to evaluate whether Britain in general and its multicultural model in particular can accomodate cultural hybridity and even encourage it, or whether British multiculturalism generates, knowingly or not, a refusal of that hybridity. Qualititative fieldwork between 2000 and 2005 in two inner city Bristol wards, Easton and St. Paul’s, is used to back up the analysis. The recent evolution of the British model leads to questions about its future, and the hybridation of other models of the governance of diversity in Europe, in particular the French republican model.

  19. Effects of SiC amount on phase compositions and properties of Ti3SiC2-based composites

    Institute of Scientific and Technical Information of China (English)

    蔡艳芝; 殷小玮; 尹洪峰

    2015-01-01

    The phase compositions and properties of Ti3SiC2-based composites with SiC addition of 5%−30% in mass fraction fabricated by in-situ reaction and hot pressing sintering were studied. SiC addition effectively prevented TiC synthesis but facilitated SiC synthesis. The Ti3SiC2/TiC−SiC composite had better oxidation resistance when SiC added quantity reached 20% but poorer oxidation resistance with SiC addition under 15%than Ti3SiC2/TiC composite at higher temperatures. There were more than half of the original SiC and a few Ti3SiC2 remaining in Ti3SiC2/TiC−SiC with 20% SiC addition, but all constituents in Ti3Si2/TiC composite were oxidized after 12 h in air at 1500 °C. The oxidation scale thickness of TS30, 1505.78μm, was near a half of that of T, 2715μm, at 1500 °C for 20 h. Ti3SiC2/TiC composite had a flexural strength of 474 MPa, which was surpassed by Ti3SiC2/TiC−SiC composites when SiC added amount reached 15%. The strength reached the peak of 518 MPa at 20%SiC added amount.

  20. Gate leakage mechanisms in strained Si devices

    Science.gov (United States)

    Yan, L.; Olsen, S. H.; Kanoun, M.; Agaiby, R.; O'Neill, A. G.

    2006-11-01

    This work investigates gate leakage mechanisms in advanced strained Si /SiGe metal-oxide-semiconductor field-effect transistor (MOSFET) devices. The impact of virtual substrate Ge content, epitaxial material quality, epitaxial layer structure, and device processing on gate oxide leakage characteristics are analyzed in detail. In state of the art MOSFETs, gate oxides are only a few nanometers thick. In order to minimize power consumption, leakage currents through the gate must be controlled. However, modifications to the energy band structure, Ge diffusion due to high temperature processing, and Si /SiGe material quality may all affect gate oxide leakage in strained Si devices. We show that at high oxide electric fields where gate leakage is dominated by Fowler-Nordheim tunneling, tensile strained Si MOSFETs exhibit lower leakage levels compared with bulk Si devices. This is a direct result of strain-induced splitting of the conduction band states. However, for device operating regimes at lower oxide electric fields Poole-Frenkel emissions contribute to strained Si gate leakage and increase with increasing virtual substrate Ge content. The emissions are shown to predominantly originate from surface roughness generating bulk oxide traps, opposed to Ge diffusion, and can be improved by introducing a high temperature anneal. Gate oxide interface trap density exhibits a dissimilar behavior and is highly sensitive to Ge atoms at the oxidizing surface, degrading with increasing thermal budget. Consequently advanced strained Si /SiGe devices are inadvertently subject to a potential tradeoff between power consumption (gate leakage current) and device reliability (gate oxide interface quality).

  1. Nanoscale SiC production by ballistic ion beam mixing of C/Si multilayer structures

    Science.gov (United States)

    Battistig, G.; Zolnai, Z.; Németh, A.; Panjan, P.; Menyhárd, M.

    2016-05-01

    The ion beam-induced mixing process using Ar+, Ga+, and Xe+ ion irradiation has been used to form SiC rich layers on the nanometer scale at the interfaces of C/Si/C/Si/C multilayer structures. The SiC depth distributions were determined by Auger electron spectroscopy (AES) depth profiling and were compared to the results of analytical models developed for ballistic ion mixing and local thermal spike induced mixing. In addition, the measured SiC depth distributions were correlated to the Si and C mixing profiles simulated by the TRIDYN code which can follow the ballistic ion mixing process as a function of ion fluence. Good agreement has been found between the distributions provided by AES depth profiling and TRIDYN on the assumption that the majority of the Si (C) atoms transported to the neighboring C (Si) layer form the SiC compound. The ion beam mixing process can be successfully described by ballistic atomic transport processes. The results show that SiC production as a function of depth can be predicted, and tailored compound formation on the nanoscale becomes feasible, thus leading to controlled synthesis of protective SiC coatings at room temperature.

  2. Influence of Si content and heat treatment on microstructure of Al-Fe-Si alloys

    Institute of Scientific and Technical Information of China (English)

    Zhao Yuhua; Wang Xiubin; Liu Yulin; Wang Chao

    2014-01-01

    The effect of Si addition and heat treatment on the Al-5wt.%Fe al oy has been investigated by OM, SEM-EDS and XRD. The results show that the Si plays a significant role in refining the primary Al3Fe phase. It was found that the addition of 3.0wt.% Si made the al oy present the finest and wel -distributed primary Al3Fe phase, but the Al3Fe phase almost disappeared when 5wt.% Si was added. With further increase in the Si content, some Fe-rich phases appeared in the inter-grains and coarsened. In addition, the heat treatments exert a significant impact on the microstructural evolution of the Al-5wt.%Fe-5wt.%Si al oy. After heat treatment for 28 hours at 590 ºC, the coarse platelet or blocky Fe-rich phase in Al-5wt.%Fe-5wt.%Si al oys was granulated; the phase transformation from metastable platelet Al3FeSi and blocky Al8Fe2Si to stable Al5FeSi had occurred. With the extension of heat treatment, the Si phase coarsened gradual y.

  3. Investigation on The Properties of Fe-Si3N4 Bonded SiC Composite

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong; FENG Di; PENG Dayan

    2005-01-01

    The mechanical properties of pressureless sintering Fe-Si3N4 bonded SiC and Si3 N4 bonded SiC with same manufacture process have been compared in this paper.The oxidizing mechanism of Fe-Si3 N4 bonded SiC ceramic matrix composite has been investigated especially through TG-DSC (thermo gravimetric analysis-differential scanning calorimeter) experiment. During oxidation procedure the main reaction is the oxidation of SiC and Si3N4, SiO2 which form protecting film to prevent further oxidizing. And residual iron in the samples become Fe2 O3 and Fe3O4, the oxidation kinetics at 1100 ~ 1300℃ of re-Si3 N4 bonded SiC has been studied especially. The weight gain per unit area at initial stage changes according to beeline rule, in the middle according to conic, and in the last oxidation period follows parabola rule.

  4. Nano-SiC/SiC anti-oxidant coating on the surface of graphite

    Science.gov (United States)

    Jafari, H.; Ehsani, N.; Khalifeh-Soltani, S. A.; Jalaly, M.

    2013-01-01

    In this research, a dual-layer coating has been used to improve high temperature oxidation resistance of graphite substrate. For first layer, silicon carbide was applied by pack cementation method. Powder pack consisted of Si, SiC and Al2O3 and heat-treated at 1650 °C in an argon atmosphere. SEM and XRD characterizations confirmed formation of SiC diffusion coating with about 500 μm including compositionally gradient of C and Si elements. Electrophoretic deposition (EPD) was used to deposit nano SiC (SiCn) particles as second layer. Thickness of second layer of SiCn in corresponded optimal situation was 50 μm. Samples with single and dual layers were investigated in oxidation test at 1600 °C. Results showed that an extreme increase was occurred in oxidation resistance after application of second layer of nano SiC. Weight loss value for single layer coating of SiC and dual layer coating of SiCn/SiC after oxidation test for 28 h at 1600 °C were 29 wt.% and 2.4 wt.%, respectively.

  5. Improving Passivation Process of Si Nanocrystals Embedded in SiO2 Using Metal Ion Implantation

    Directory of Open Access Journals (Sweden)

    Jhovani Bornacelli

    2013-01-01

    Full Text Available We studied the photoluminescence (PL of Si nanocrystals (Si-NCs embedded in SiO2 obtained by ion implantation at MeV energy. The Si-NCs are formed at high depth (1-2 μm inside the SiO2 achieving a robust and better protected system. After metal ion implantation (Ag or Au, and a subsequent thermal annealing at 600°C under hydrogen-containing atmosphere, the PL signal exhibits a noticeable increase. The ion metal implantation was done at energies such that its distribution inside the silica does not overlap with the previously implanted Si ion . Under proper annealing Ag or Au nanoparticles (NPs could be nucleated, and the PL signal from Si-NCs could increase due to plasmonic interactions. However, the ion-metal-implantation-induced damage can enhance the amount of hydrogen, or nitrogen, that diffuses into the SiO2 matrix. As a result, the surface defects on Si-NCs can be better passivated, and consequently, the PL of the system is intensified. We have selected different atmospheres (air, H2/N2 and Ar to study the relevance of these annealing gases on the final PL from Si-NCs after metal ion implantation. Studies of PL and time-resolved PL indicate that passivation process of surface defects on Si-NCs is more effective when it is assisted by ion metal implantation.

  6. Atomic diffusion in annealed CU/SiO2/Si (100) system prepared by magnetron sputtering

    International Nuclear Information System (INIS)

    Cu thin films are deposited on p-type Si (100) substrates by magnetron sputtering at room temperature. The interface reaction and atomic diffusion of Cu/SiO2/Si (100) systems are studied by x-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). Some significant results can be obtained. The onset temperature of interdiffusion for Cu/SiO2/Si(100) is 350 °C. With the annealing temperature increasing, the interdiffusion becomes more apparent. The calculated diffusion activation energy is about 0.91 eV. For the CU/SiO2/Si (100) systems copper silicides are not formed below an annealing temperature of 350 °C. The formation of the copper silicides phase is observed when the annealing temperature arrives at 450 °C. (condensed matter: structure, thermal and mechanical properties)

  7. Designing the Si(100) conversion into SiC(100) by Ge

    Energy Technology Data Exchange (ETDEWEB)

    Nader, Richard; Masri, Pierre [Groupe d' Etude des Semiconducteurs, CNRS-UMR 5650, Universite de Montpellier II, CC 074, 34095 Montpellier, Cedex 5 (France); Niebelschuetz, Florentina; Pezoldt, Joerg [FG Nanotechnologie, Institut fuer Mikro- und Nanotechnologien, TU Ilmenau, Postfach 100565, 98684 Ilmenau (Germany); Kulikov, Dmitri V.; Kharlamov, Vladimir V.; Trushin, Yurii V. [Department of Theoretical Bases of Microelectronics, Ioffe Physical Technical Institute, ul. Polytekhnicheskaya 26, St. Petersburg 194021 (Russian Federation); Nanostructures Physics Laboratory, St. Petersburg Research and Education Center of Science and Technology, Khlopina 8/3, St. Petersburg 195220 (Russian Federation)

    2010-02-15

    The deposition of Germanium (Ge) prior to the conversion of Si(100) into 3C-SiC(100) results in changes of the structure and surface morphology of the formed silicon carbide layer. First of all it reduces the thickness of the 3C-SiC layer grown during the conversion process and therefore the probability of voids formation. Secondly, it increases the nucleation density of the formed 3C-SiC nuclei and therefore, decreases the grain size at Ge coverages below two monolayers. These affect the roughness of the SiC surface positively by modifying the width of the SiC-Si interface. If the Ge coverages exceed two monolayers the structural and morphological properties begin to degrade. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. SiO x /SiN y multilayers for photovoltaic and photonic applications

    Science.gov (United States)

    Nalini, Ramesh Pratibha; Khomenkova, Larysa; Debieu, Olivier; Cardin, Julien; Dufour, Christian; Carrada, Marzia; Gourbilleau, Fabrice

    2012-02-01

    Microstructural, electrical, and optical properties of undoped and Nd3+-doped SiO x /SiN y multilayers fabricated by reactive radio frequency magnetron co-sputtering have been investigated with regard to thermal treatment. This letter demonstrates the advantages of using SiN y as the alternating sublayer instead of SiO2. A high density of silicon nanoclusters of the order 1019 nc/cm3 is achieved in the SiO x sublayers. Enhanced conductivity, emission, and absorption are attained at low thermal budget, which are promising for photovoltaic applications. Furthermore, the enhancement of Nd3+ emission in these multilayers in comparison with the SiO x /SiO2 counterparts offers promising future photonic applications. PACS: 88.40.fh (Advanced materials development), 81.15.cd (Deposition by sputtering), 78.67.bf (Nanocrystals, nanoparticles, and nanoclusters).

  9. Light emissions from LiNbO sub 3 /SiO sub 2 /Si structures

    CERN Document Server

    Wu, X L; Tang, N; Deng, S S; Bao, X M

    2003-01-01

    LiNbO sub 3 (LN) films with a high degree of (006) texture were deposited on Si-based dense SiO sub 2 layers by pulsed laser deposition. After annealing, the LN/SiO sub 2 /Si structures were revealed to have ultraviolet-, green-, and red-emitting properties related to self-trapped excitons and E' defect pairs in the SiO sub 2 surface, which are induced by the photorefractive effect of the LN films. The emission wavelength can be tuned by introducing different dopants into the LN films. Waveguiding properties of the structures were demonstrated. The results obtained indicate that the LN/SiO sub 2 /Si structures could be expected to have important applications in modern optoelectronic integration. (letter to the editor)

  10. Time-resolved photoluminescence of SiOx encapsulated Si

    Science.gov (United States)

    Kalem, Seref; Hannas, Amal; Österman, Tomas; Sundström, Villy

    Silicon and its oxide SiOx offer a number of exciting electrical and optical properties originating from defects and size reduction enabling engineering new electronic devices including resistive switching memories. Here we present the results of photoluminescence dynamics relevant to defects and quantum confinement effects. Time-resolved luminescence at room temperature exhibits an ultrafast decay component of less than 10 ps at around 480 nm and a slower component of around 60 ps as measured by streak camera. Red shift at the initial stages of the blue luminescence decay confirms the presence of a charge transfer to long lived states. Time-correlated single photon counting measurements revealed a life-time of about 5 ns for these states. The same quantum structures emit in near infrared close to optical communication wavelengths. Nature of the emission is described and modeling is provided for the luminescence dynamics. The electrical characteristics of metal-oxide-semiconductor devices were correlated with the optical and vibrational measurement results in order to have better insight into the switching mechanisms in such resistive devices as possible next generation RAM memory elements. ``This work was supported by ENIAC Joint Undertaking and Laser-Lab Europe''.

  11. La sauvegarde des grandes oeuvres de l'ingénierie du XXème siècle

    CERN Document Server

    Graf, Franz

    2016-01-01

    Consacré à la sauvegarde des grandes oeuvres de l’ingénierie du XXe siècle, ce premier numéro des Cahiers du TSAM explore le devenir de certaines des plus remarquables et emblématiques structures en béton du siècle passé. A travers les fi gures d’héroïques constructeurs, il interroge l’héritage construit des ingénieurs, convoquant les plus audacieux d’entre eux (Freyssinet, Isler, Maillart, Nervi, Vierendeel, etc.). Alors que la sauvegarde de l’architecture du XXe siècle s’est récemment constituée en discipline à part entière, la préservation des ouvrages de l’ingénierie de cette période est encore balbutiante. Considérés trop souvent sous le seul point de vue de la sécurité ou de la maintenance, ces ouvrages s’avèrent parfois de véritables chefs-d’oeuvre, jalons d’un «art de l’ingénieur» à la frontière entre performance technique et beauté plastique. Ces cahiers sont donc l’occasion d’initier, à l’appui d’exemples et de projets de sauvegarde con...

  12. p-n Junction Diodes Fabricated on Si-Si/Ge Heteroepitaxial Films

    Science.gov (United States)

    Das, K.; Mazumder, M. D. A.; Hall, H.; Alterovitz, Samuel A. (Technical Monitor)

    2000-01-01

    A set of photolithographic masks was designed for the fabrication of diodes in the Si-Si/Ge material system. Fabrication was performed on samples obtained from two different wafers: (1) a complete HBT structure with an n (Si emitter), p (Si/Ge base), and an n/n+ (Si collector/sub-collector) deposited epitaxially (MBE) on a high resistivity p-Si substrate, (2) an HBT structure where epitaxial growth was terminated after the p-type base (Si/Ge) layer deposition. Two different process runs were attempted for the fabrication of Si-Si/Ge (n-p) and Si/Ge-Si (p-n) junction diodes formed between the emitter-base and base-collector layers, respectively, of the Si-Si/Ge-Si HBT structure. One of the processes employed a plasma etching step to expose the p-layer in the structure (1) and to expose the e-layer in structure (2). The Contact metallization used for these diodes was a Cu-based metallization scheme that was developed during the first year of the grant. The plasma-etched base-collector diodes on structure (2) exhibited well-behaved diode-like characteristics. However, the plasma-etched emitter-base diodes demonstrated back-to-back diode characteristics. These back-to back characteristics were probably due to complete etching of the base-layer, yielding a p-n-p diode. The deep implantation process yielded rectifying diodes with asymmetric forward and reverse characteristics. The ideality factor of these diodes were between 1.6 -2.1, indicating that the quality of the MBE grown epitaxial films was not sufficiently high, and also incomplete annealing of the implantation damage. Further study will be conducted on CVD grown films, which are expected to have higher epitaxial quality.

  13. Remote plasma-assisted oxidation of SiC: a low temperature process for SiC-SiO2 interface formation that eliminates interfacial Si oxycarbide transition regions

    International Nuclear Information System (INIS)

    Remote plasma-assisted oxidation of SiC is a low temperature process, 300 deg. C, for the formation of device quality interfaces on SiC. This paper discusses two aspects of the process: (i) the motivation for eliminating high temperature oxidation processes that can generate silicon oxycarbide, Si-O-C, interfacial regions which can be a source of interfacial defects and (ii) the kinetics of the remote plasma-assisted oxidation process that effectively eliminates interfacial Si oxycarbide transition regions. The differences between interfacial relaxation at Si-SiO2 and SiC-SiO2 are based on the relative stabilities of the suboxides of Si and SiC, SiOx and (Si,C)Ox, respectively

  14. Abiologic silicon isotope fractionation between aqueous Si and Fe(III)-Si gel in simulated Archean seawater: Implications for Si isotope records in Precambrian sedimentary rocks

    Science.gov (United States)

    Zheng, Xin-Yuan; Beard, Brian L.; Reddy, Thiruchelvi R.; Roden, Eric E.; Johnson, Clark M.

    2016-08-01

    Precambrian Si-rich sedimentary rocks, including cherts and banded iron formations (BIFs), record a >7‰ spread in 30Si/28Si ratios (δ30Si values), yet interpretation of this large variability has been hindered by the paucity of data on Si isotope exchange kinetics and equilibrium fractionation factors in systems that are pertinent to Precambrian marine conditions. Using the three-isotope method and an enriched 29Si tracer, a series of experiments were conducted to constrain Si isotope exchange kinetics and fractionation factors between amorphous Fe(III)-Si gel, a likely precursor to Precambrian jaspers and BIFs, and aqueous Si in artificial Archean seawater under anoxic conditions. Experiments were conducted at room temperature, and in the presence and absence of aqueous Fe(II) (Fe(II)aq). Results of this study demonstrate that Si solubility is significantly lower for Fe-Si gel than that of amorphous Si, indicating that seawater Si concentrations in the Precambrian may have been lower than previous estimates. The experiments reached ˜70-90% Si isotope exchange after a period of 53-126 days, and the highest extents of exchange were obtained where Fe(II)aq was present, suggesting that Fe(II)-Fe(III) electron-transfer and atom-exchange reactions catalyze Si isotope exchange through breakage of Fe-Si bonds. All experiments except one showed little change in the instantaneous solid-aqueous Si isotope fractionation factor with time, allowing extraction of equilibrium Si isotope fractionation factors through extrapolation to 100% isotope exchange. The equilibrium 30Si/28Si fractionation between Fe(III)-Si gel and aqueous Si (Δ30Sigel-aqueous) is -2.30 ± 0.25‰ (2σ) in the absence of Fe(II)aq. In the case where Fe(II)aq was present, which resulted in addition of ˜10% Fe(II) in the final solid, creating a mixed Fe(II)-Fe(III) Si gel, the equilibrium fractionation between Fe(II)-Fe(III)-Si gel and aqueous Si (Δ30Sigel-aqueous) is -3.23 ± 0.37‰ (2σ). Equilibrium

  15. Experimental and thermodynamic assessments of substitutions in the AlFeSi, FeMnSi, FeSiZr and AlCaFeSi systems (65 wt % Si) - solidification simulation

    International Nuclear Information System (INIS)

    The substitutions of Al Si, Fe Mn and Fe Zr in some intermetallic compounds of the Al-Fe-Si, Fe-Mn-Si and Fe-Si-Zr systems are modelled in the Si-rich corner using a two sublattice model. The solidification paths of the studied alloys are determined at equilibrium. The ascalculated phase volume fractions of the alloys are compared to the experimental ones. Finally, a solidification simulation using the Gulliver-Scheil's model is performed in order to explain the formation of some precipitates experimentally observed. (authors). 14 figs., 19 refs

  16. Morte e pessoa entre os kaxinawá

    Directory of Open Access Journals (Sweden)

    Cecilia McCallum

    1996-10-01

    Full Text Available Este artigo apresenta uma etnografia do pensamento e das práticas relativos à morte, ao processo de morrer e à condição de pessoa entre os Kaxinawá (Huni Kuin da Amazônia Ocidental (Brasil e Peru Oriental. Articula o simbolismo de gênero, resultante das práticas cotidianas, com a forma das relações sociais estabelecidas entre a pessoa agonizante e os espíritos terrestres, aquáticos e celestiais em cada etapa do processo de morrer. A etnografia visa fornecer um contraponto crítico ao modelo que trata dessas mesmas relações e de seus processos, conhecido nos estudos americanistas como "economia simbólica da predação", no qual a "troca" funciona ao mesmo tempo como processo básico e como metáfora. O artigo sugere que uma análise da morte entre os Kaxinawá deve enfatizar o ciclo inteiro da produção consumptiva e não apenas o simbolismo da predação e da troca.This article is an ethnography of thinking and practice about death, the process of dying and personhood among the Cashinahua (Huni Kuin of Western Amazonia (Brazil and Eastern Peru. It relates gender symbolism, arising from the practice of daily life, to the form that social relations between the moribund person and terrestrial, aquatic and celestial spirits take during each stage of dying. This ethnography is provided as a critical counterpoint to the model of such relations and the processes that surround them known in Americanist studies as "the symbolic economy of predation", in which "exchange" functions as the key process and metaphor. The paper suggests that any analysis of death among the Cashinahua must place emphasis on the whole cycle of consumptive production, not just on the symbolism of predation and exchange.

  17. Dos años entre los indios

    Directory of Open Access Journals (Sweden)

    Ardila Ardila Olga Felisa

    1996-06-01

    Full Text Available

    La obra constituye la traducción del alemán publicada originalmente en dos volúmenes por E. Wasmuth en Berlín en 1909. En 1967 la Akademische Druck-u Verlagsanstalt en Graz (Austria publicó la segunda edición de la obra original, sobre la cual se trabajó la presente versión en español. La traducción estuvo a cargo de la antropóloga María Mercedes Ortiz. Koch-Grünberg se dedicó al estudio de la filología clásica pero con el tiempo se fue interesando cada vez más por el estudio de los pueblos autóctonos de Suramérica. En 1903 realizó su primera expedición a partir del noroeste brasilero hasta Colombia, en la región comprendida entre el alto río Negro y el Yapurá, área muy poco explorada hasta el momento. La obra Dos años entre los indios resume los resultados básicos de esta expedición. El autor alemán presenta el relato de sus cuatro viajes e ilustra con un mapa la ruta de su expedición a partir del Amazonas. Además del noroeste brasilero, el autor recorre un área importante del territorio colombiano, especialmente la zona del actual departamento del Vaupés. El libro está escrito en forma de un diario de viaje en el que se destacan sus observaciones etnográficas y lingüísticas, especialmente en lo que respecta a la cultura material, el ritual, el arte, las diferentes lenguas nativas habladas en la región y las relaciones de afinidad existentes entre dichas lenguas.

  18. Peter Shepheard Espacios intermedios entre la arquitectura y el paisaje

    Directory of Open Access Journals (Sweden)

    Juan J. Tuset

    2015-05-01

    Full Text Available ResumenAcabada la Segunda Guerra Mundial, el Movimiento Moderno se debatió entre su continuidad o crisis, lo que llevó a numerosos arquitectos y críticos a formular teorías y adoptar actitudes disciplinares trasgresoras con el momento. Una de ellas fue la del arquitecto, urbanista y paisajista inglés Peter Shepheard quien desarrolló una actividad profesional, teórica y docente de la que se trasluce la relevancia del concepto in between como una de las claves defi nitorias del diseño arquitectónico en la segunda mitad del siglo XX. Para Shepheard el diseño moderno debía ser el encuentro entre la arquitectura, el urbanismo y el paisaje. Aseveración que vino precedida por diferentes tipos de obras arquitectónicas, proyectos urbanos, artículos y publicaciones sobre el diseño del paisaje y del jardínque le convirtieron en una voz de referencia en el contexto británico. Shepheard alentó a los paisajistas a convencerse de que las tres disciplinas anteriores convergen en un sola y que la responsabilidad de la joven profesión de arquitecto del paisaje es asumir el reto del diseño arquitectónico, urbano y paisajístico como un todo en la búsqueda y defi nición de espacios intermedios entre la arquitectura y el paisaje. AbstractAfter the Second World War, Modernism started to debate his continuity or crisis. This led many architects and critics to formulate theories and take up breaking disciplinary attitudes against that time. One of them was the English architect, urban planner and landscape designer Peter Shepheard who developed a professional, theoretical and academic career where the concept in between got relevance as one of the defi ning keys of the architectural design in the second half of the twentieth century. To Shepheard modern design should be the encounter between architecture, urbanism and landscape. This claim was preceded by different types of architectural works, urban projects, articles and publications on

  19. Molecular Structures of Al/Si and Fe/Si Coprecipitates and the Implication for Selenite Removal.

    Science.gov (United States)

    Chan, Ya-Ting; Kuan, Wen-Hui; Tzou, Yu-Min; Chen, Tsan-Yao; Liu, Yu-Ting; Wang, Ming-Kuang; Teah, Heng-Yi

    2016-04-20

    Aluminum and iron oxides have been often used in the coagulation processes during water purification due to their unique surface properties toward anions. In the presence of silica, the coprecipitation of Al/Si or Fe/Si might decrease the efficiency of wastewater purification and reuse. In this study, surface properties and molecular structures of Al/Si and Fe/Si coprecipitates were characterized using spectroscopic techniques. Also, the selenite removal efficiency of Al/Si and Fe/Si coprecipitates in relation to their surface and structural properties was investigated. While dissolved silicate increased with increasing pH from Fe/Si coprecipitates, less than 7% of silicate was discernible from Al/Si samples over the range from acidic to alkaline conditions. Our spectroscopic results showed that the associations between Al and Si were relatively stronger than that between Fe and Si in coprecipitates. In Al/Si coprecipitates, core-shell structures were developed with AlO6/AlO4 domains as the shells and Si frameworks polymerized from the SiO2 as the cores. However, Si framework remained relatively unchanged upon coprecipitation with Fe hydroxides in Fe/Si samples. The Si core with Al shell structure of Al/Si coprecipitates shielded the negative charges from SiO2 and thereby resulted in a higher adsorption capacity of selenite than Fe/Si coprecipitates.

  20. Molecular Structures of Al/Si and Fe/Si Coprecipitates and the Implication for Selenite Removal

    Science.gov (United States)

    Chan, Ya-Ting; Kuan, Wen-Hui; Tzou, Yu-Min; Chen, Tsan-Yao; Liu, Yu-Ting; Wang, Ming-Kuang; Teah, Heng-Yi

    2016-04-01

    Aluminum and iron oxides have been often used in the coagulation processes during water purification due to their unique surface properties toward anions. In the presence of silica, the coprecipitation of Al/Si or Fe/Si might decrease the efficiency of wastewater purification and reuse. In this study, surface properties and molecular structures of Al/Si and Fe/Si coprecipitates were characterized using spectroscopic techniques. Also, the selenite removal efficiency of Al/Si and Fe/Si coprecipitates in relation to their surface and structural properties was investigated. While dissolved silicate increased with increasing pH from Fe/Si coprecipitates, less than 7% of silicate was discernible from Al/Si samples over the range from acidic to alkaline conditions. Our spectroscopic results showed that the associations between Al and Si were relatively stronger than that between Fe and Si in coprecipitates. In Al/Si coprecipitates, core-shell structures were developed with AlO6/AlO4 domains as the shells and Si frameworks polymerized from the SiO2 as the cores. However, Si framework remained relatively unchanged upon coprecipitation with Fe hydroxides in Fe/Si samples. The Si core with Al shell structure of Al/Si coprecipitates shielded the negative charges from SiO2 and thereby resulted in a higher adsorption capacity of selenite than Fe/Si coprecipitates.

  1. Dependence of Morphology of SiOx Nanowires on the Supersaturation of Au-Si Alloy Liquid Droplets Formed on the Au-Coated Si Substrate

    Institute of Scientific and Technical Information of China (English)

    张晗; 李吉学; 张泽; 金爱子

    2001-01-01

    A thermodynamic theory about the dependence of morphology of SiOx nanowires on the super-saturation of alloy liquid droplets has been proposed on the basis of the vapour-liquid-solid growth mechanism and has been supported experimentally. By changing the Si concentration in the Au-Si liquid droplets formed on the Au-coated Si substrate, firework-, tulip- and bud-shaped SiOx nanowires were synthesized by a thermal evaporation method and distributed concentrically around some void defects in the Si substrate. Voids were formed underneath the surface of the Si substrate during the thermal evaporation at 850℃ and resulted in the Si-concentration deficient thus different saturation of Au-Si droplets. Electron microscopy analysis showed that the nanowires had an amorphous structure and were terminated by Au-Si particles.

  2. 微腔中nc-Si/SiN超晶格的光致发光%Photoluminescence of nc-Si/SiN Superlattices Embedded in Optical Microcavities

    Institute of Scientific and Technical Information of China (English)

    陈三; 黄信凡; 钱波; 陈坤基; 岑展鸿; 刘艳松; 韩培高; 马忠元; 徐骏; 李伟

    2006-01-01

    We fabricate a-Si/a-SiNz superlattices and a one-dimensional amorphous silicon nitride photonic crystal microcavity by plasma enhancement chemical vapor deposition (PECVD). To improve the light-emitting efficiency of the nc-Si/a-SiNz superlattices, which are made from a-Si/a-SiNz superlattices by laser annealing, an nc-Si quantum dot array is inserted into the photonic crystal microcavity. Raman spectroscopy and transmission electron microscopy analysis show that nc-Si with a size of 4nm,which is close to the designed thickness of the a-Si sublayers,is formed in the a-Si sublayers. Owing to microcavity effects,the PL peak of the nc-Si/a-SiNz superlattices embedded in the microcavity is strongly narrowed, and the intensity of the PL is enhanced by two orders of magnitude with respect to the emission of λ/2-thick nc-Si/a-SiNz superlattices. Light emission at a cavity-resonant frequency from the nc-Si/a-SiNz superlattices is enhanced while other frequencies are forbidden. This leads to the narrowing of the PL spectrum and enhancement of the intensity.%研究了一维光子晶体微腔结构对nc-Si/a-SiNz超晶格发射的调制.一维光子晶体微腔采用两种具有不同折射率的非化学组分非晶氮化硅的周期调制结构,腔中嵌入采用激光晶化方法制备的硅量子点阵列,从Raman谱和透射电子显微镜分析得到其尺寸约为3~4 nm.从光致发光谱上观察到明显的选模作用、明显变窄的发光峰以及约两个量级的发光强度的增强.微腔对硅量子点阵列发光的调制主要表现在两个方面:共振模式的增强和非共振模式的抑制.硅量子点中位于腔共振模式的辐射跃迁被增强,非共振模式的辐射跃迁被抑制,因此位于腔共振频率处的跃迁通道成为硅量子点中唯一的辐射跃迁通道,导致光致发光谱的窄化和强度的增强.因此,在提高硅材料发光效率方面,光子晶体微腔具有非常大的应用前景.

  3. siRNA and RNAi optimization.

    Science.gov (United States)

    Alagia, Adele; Eritja, Ramon

    2016-05-01

    The discovery and examination of the posttranscriptional gene regulatory mechanism known as RNA interference (RNAi) contributed to the identification of small interfering RNA (siRNA) and the comprehension of its enormous potential for clinical purposes. Theoretically, the ability of specific target gene downregulation makes the RNAi pathway an appealing solution for several diseases. Despite numerous hurdles resulting from the inherent properties of siRNA molecule and proper delivery to the target tissue, more than 50 RNA-based drugs are currently under clinical testing. In this work, we analyze the recent literature in the optimization of siRNA molecules. In detail, we focused on describing the most recent advances of siRNA field aimed at optimize siRNA pharmacokinetic properties. Special attention has been given in describing the impact of RNA modifications in the potential off-target effects (OTEs) such as saturation of the RNAi machinery, passenger strand-mediated silencing, immunostimulation, and miRNA-like OTEs as well as to recent developments on the delivery issue. The novel delivery systems and modified siRNA provide significant steps toward the development of reliable siRNA molecules for therapeutic use. WIREs RNA 2016, 7:316-329. doi: 10.1002/wrna.1337 For further resources related to this article, please visit the WIREs website. PMID:26840434

  4. Microstructures in Centrifugal Casting of SiCp/AlSi9Mg Composites with Different Mould Rotation Speeds

    Institute of Scientific and Technical Information of China (English)

    WANG Kai; SUN Wenju; LI Bo; XUIE Hansong; LIU Changming

    2011-01-01

    Two ingots were produced by centrifugal casting at mould rotational speeds of 600 rpm and 800 rpm using 20 vol% SiCp/AlSi9Mg composite melt, respectively. The microstructure along the radial direction of cross-sectional sample of ingots was presented. SiC particles migrated towards the external circumference of the tube, and the distribution of SiC particles became uniform under centrifugal force. Voids in 20 vol% SiCp/AlSi9Mg composite melt migrated towards the inner circumference of the tube. The quantitative analysis results indicated that not only SiC particles but also primary a phases segregated greatly in centrifugal casting resulting from the transportation behavior of constitutions with different densities in the SiCp/AlSi9Mg composite melt. In addition, the eutectic Si was broken owing to the motion of SiCp/AlSi9Mg composite melt during centrifugal casting.

  5. SiC and their interfacial behavior in SiCp/ZL109 composites%SiC颗粒增强Al-Si复合材料中的SiC及其界面

    Institute of Scientific and Technical Information of China (English)

    隋贤栋; 罗承萍; 骆灼旋; 欧阳柳章

    2000-01-01

    以常规TEM为工具,对SiCp/ZL109复合材料中SiC颗粒及其界面进行了研究,除观察到大量α型六方6H SiC外,还观察到少量α型六方4H和菱形15R SiC.观察到的都是单一的SiC/Al及SiC界面,无论是SiC/Al或SiC/Si界面,界面清洁,结合紧密,无孔洞,无反应过渡层.

  6. Retrovirus-delivered siRNA

    Directory of Open Access Journals (Sweden)

    Devroe Eric

    2002-08-01

    Full Text Available Abstract Background The ability of transfected synthetic small interfering (si RNAs to suppress the expression of specific transcripts has proved a useful technique to probe gene function in mammalian cells. However, high production costs limit this technology's utility for many laboratories and experimental situations. Recently, several DNA-based plasmid vectors have been developed that direct transcription of small hairpin RNAs, which are processed into functional siRNAs by cellular enzymes. Although these vectors provide certain advantages over chemically synthesized siRNAs, numerous disadvantages remain including merely transient siRNA expression and low and variable transfection efficiency. Results To overcome several limitations of plasmid-based siRNA, a retroviral siRNA delivery system was developed based on commerically available vectors. As a pilot study, a vector was designed to target the human Nuclear Dbf2-Related (NDR kinase. Cells infected with the anti-NDR siRNA virus dramatically downregulate NDR expression, whereas control viruses have no effect on total NDR levels. To confirm and extend these findings, an additional virus was constructed to target a second gene, transcriptional coactivator p75. Conclusion The experiments presented here demonstrate that retroviruses are efficient vectors for delivery of siRNA into mammalian cells. Retrovirus-delivered siRNA provides significant advancement over previously available methods by providing efficient, uniform delivery and immediate selection of stable "knock-down" cells. This development should provide a method to rapidly assess gene function in established cell lines, primary cells, or animals.

  7. Encontro entre teleologia e deontologia: uma análise a partir da interpretação contemporânea de Paul Ricoeur

    Directory of Open Access Journals (Sweden)

    Élsio José Corá

    2011-08-01

    Full Text Available http://dx.doi.org/10.5007/1677-2954.2010v9n1p43Este trabalho pretende analisar a relação entre teleologia e deontologia, sob o ponto de vista contemporâneo de Paul Ricoeur. Objetiva, ainda, fazer uma classificação dos conceitos utilizados nessa relação, que incluem a estima de si, respeito de si, vida boa, solicitude e alteridade, conceitos tratados, principalmente no sétimo e oitavo capítulo da obra O si-mesmo como um outro. O estudo revela que para interrelacionar as propostas da ética teleológica (aristotélica e a deontológica (kantiana é preciso retomar a estrutura conceitual desenvolvida por Ricoeur, ou seja a tese da primazia da ética sobre a moral, bem como no desenvolvimento dessa tese, a necessidade da ética passar pelo crivo da norma.

  8. Re-encontro: entre memória e identidade

    OpenAIRE

    Diogo, Dora Maria Tracana

    2012-01-01

    Nesta dissertação, trabalhei sobre a questão de identidade e a sua ligação à memória. Inspirei- me na aldeia dos meus avós, “Panoias”. Aldeia onde passei bons momentos da minha infância, e que tanto peso teve na minha formação como pessoa. A experiencia pessoal do contacto com a aldeia, tão diferente da cidade escolhida por minha mãe para habitar (Coimbra) - e a luta atual com a doença - levou-me a procurar explorar o tema, “RE-ENCONTRO: ENTRE MEMÓRIA E IDENTIDADE”, onde pro...

  9. Risco ocupacional de adquirir tuberculose entre trabalhadores de enfermagem hospitalar

    Directory of Open Access Journals (Sweden)

    Elisabete Takeda

    2001-09-01

    Full Text Available Nos hospitais, os indivíduos tuberculosos são atendidos por vários profissionais e dentre eles os trabalhadores de enfermagem. Esses trabalhadores estão sujeitos a riscos de infecção tuberculosa. O estudo objetivou: levantar o número de trabalhadores de enfermagem do hospital que adquiriram tuberculose, e as características gerais em um período pré determinado; levantar a morbidade dessa doença e discutir o risco ocupacional entre estes trabalhadores. Em um ano os trabalhadores apresentaram risco 3.86 vezes maior e em outro, 1.47 vezes maior de adquirir a doença. Neste estudo a tuberculose foi considerada de risco ocupacional para os trabalhadores de enfermagem.

  10. Cultura organizacional: sinergias e alergias entre Hofstede e Trompenaars

    Directory of Open Access Journals (Sweden)

    Daniel Pacheco Lacerda

    2011-10-01

    Full Text Available Entre os diferentes elementos a serem considerados na gestão atualmente, os aspectos culturais têm se colocado na centralidade das discussões organizacionais. Essa posição deriva do fato de que a vantagem competitiva sustentável se origina da compreensão, respeito e utilização das diferenças de hábitos, práticas, pontos de vistas e competências. Empresas com atuação local ou global precisam atentar para as características oriundas de seu capital humano. O presente trabalho busca apresentar algumas evidências das implicações culturais a partir do prisma das dimensões culturais. Para isso é realizada uma breve revisão sobre o tema, em seguida são discutidas algumas repercussões para as organizações.

  11. Relation entre la microtexture et l'adhérence

    OpenAIRE

    DO, MT

    2005-01-01

    Une synthèse des travaux menés au LCPC depuis 10 ans sur la microtexture des surfaces de chaussée est présentée. Des progrès ont été accomplis dans la mesure et la caractérisation de la microtexture. Les nouveaux descripteurs de la microtexture ont été intégrés dans un modèle de contact pour le calcul d'un coefficient de frottement à basse vitesse. L'apport de la relation entre la microtexture et le frottement à basse vitesse à la prévision de l'adhérence est ensuite traité. La variation de l...

  12. La Cooperación Internacional entre Servicios

    Directory of Open Access Journals (Sweden)

    Pulido Gragera, Julia

    2005-01-01

    Full Text Available Los nuevos requerimientos en materia de seguridad que la comunidad internacional tiene que asumir como consecuencia de las nuevas amenazas y riesgos, obligan a que los Servicios de Inteligencia y de Información, objeto de análisis de este artículo, incrementen y mejoren la colaboración y cooperación entre ellos. En este sentido la aspiración de los Estados por poseer el máximo nivel de seguridad cediendo el mínimo de soberanía, se constituye como uno de los objetivos principales de los mismos, dificultad que se presenta, en la actualidad, para poder lograr una efectiva coordinación multilateral.…

  13. estudo comparativo entre escolas públicas e privadas

    OpenAIRE

    Vieira, Fernanda Maria Mesquita

    2012-01-01

    Este estudo tem como objetivo averiguar se existe satisfação profissional e sócio-organizacional entre membros de Direções de Escolas do Básico e do Secundário, do ensino público e privado, nomeadamente porque a investigação, nos domínios da gestão e da psicologia do trabalho e das organizações, preconiza que a satisfação profissional e a sócio-organizacional, direta ou indiretamente, se encontram ligadas à produtividade e à realização pessoal, aspetos estes que não são alheios às atuais polí...

  14. Coherencia entre el ideario y los valores en el aula.

    OpenAIRE

    Carbó-González, José María

    2013-01-01

    Estamos en tiempos de crisis, y esto es innegable, aunque a parte de las dificultades económicas, mucha gente, entre ellas el Dr. Horacio Krell, director de Ilvem (y creador del método que lleva el mismo nombre) afirman que estamos también ante una crisis de valores, y eso no es nada más que la substitución de unos valores tradicionales por unos de nuevos. El cambio no es nada nuevo, constantemente estamos en proceso de transformación, y como decía Sigmund Freud: “la herejía de una época es l...

  15. Elevages laitiers à bas intrants : entre traditions et innovations

    OpenAIRE

    Delaby, Luc; Fiorelli, Jean-Louis

    2014-01-01

    Après une période de grande stabilité des prix et des volumes produits, encadrée par une politique agricole commune forte, la filière laitière française entre dans une zone de turbulences et d’incertitudes. L’augmentation de la demande alimentaire mondiale, associée à l’abandon imminent des quotas laitiers devraient créer un climat d’enthousiasme et favoriser le développement de la production laitière en Europe. Mais ces dérégulations aboutissent aussi à de fortes tensions sur le marché mondi...

  16. Armaduras de cosido entre hormigones prefabricados y ejecutados in situ

    Directory of Open Access Journals (Sweden)

    Solas, Andrés

    1988-04-01

    Full Text Available This article deals with the study of seam reinforcements between two concretes of different types which make up a compound element prefabricated and made in situ. The advantage of this type of construction is that the individual units can be made, transported and erected more easily, although some problems may arise. These facts receive special reference throughout the article.

    Este artículo trata sobre el estudio de las armaduras de cosido entre dos hormigones, de distinta naturaleza, que componen un elemento compuesto prefabricado y ejecutado in situ. La ventaja de este tipo de construcciones es que unidades individuales pueden ser hechas, transportadas y erigidas con mayor facilidad, pudiéndose derivar también algún problema. De todo ello se hace especial referencia a lo largo del artículo.

  17. Relaciones entre actividad física y salud

    OpenAIRE

    Blasco, Tomás; Capdevila Ortís, Lluís; Cruz Feliu, Jaume

    1994-01-01

    En este trabajo se describe la evolución de las características que han guiado la labor de investigación e intervención en el campo de estudio de las relaciones entre actividad física y salud a lo largo de la última década, señalando las aportaciones realizadas por el grupo de investigación al que pertenecen los autores. Asimismo, se plantean algunas sugerencias respecto a las directrices a seguir en nuestro país en este área de estudio e intervención a partir de la situación actual

  18. Interstitial Functionalization in elemental Si

    Science.gov (United States)

    Kiefer, Boris; Fohtung, Edwin

    Societies in the 21st century will face many challenges. Materials science and materials design will be essential to address and master some if not all of these challenges. Semiconductors are among the most important technological material classes. Properties such as electrical transport are strongly affected by defects and a central goal continues to be the reduction of defect densities as much as possible in these compounds. Here we present results of interstitial Fe doping in elemental Si using first-principles DFT calculations. The preliminary results show that Fe will only occupy octahedral interstitial sites. The analysis of the electronic structure shows that the compounds are ferromagnetic and that a bandgap opens as interstitial Fe concentrations decrease, with a possible intermittent semi-metallic phase. The formation energy for interstitial Fe is unfavorable, as expected, by ~1.5 eV but becomes favorable as the chemical potential of Fe increases. Therefore, we expect that biasing the system with an external electrical field will lead to the formation of these materials. Thus, our results show that interstitial defects can be beneficial for the design of functionalities that differ significantly from those of the host material.

  19. Completely CMOS compatible SiN-waveguide-based fiber coupling structure for Si wire waveguides.

    Science.gov (United States)

    Maegami, Yuriko; Okano, Makoto; Cong, Guangwei; Ohno, Morifumi; Yamada, Koji

    2016-07-25

    For Si wire waveguides, we designed a highly efficient fiber coupling structure consisting of a Si inverted taper waveguide and a CMOS-compatible thin SiN waveguide with an SiO2 spacer inserted between them. By using a small SiN waveguide with a 310 nm-square core, the optical field can be expanded to correspond to a fiber with a 4.0-μm mode field diameter. A coupled waveguide system with the SiN waveguide and Si taper waveguide can provide low-loss and low-polarization-dependent mode conversion. Both losses in fiber-SiN waveguide coupling and SiN-Si waveguide mode conversion are no more than 1 dB in a wide wavelength bandwidth from 1.36 μm to 1.65 μm. Through a detailed analysis of the effective refractive indices in the coupled waveguide system, we can understand mode conversion accurately and also derive guidelines for reducing the polarization dependence and for shortening device length.

  20. Wear mechanism for spray deposited Al-Si/SiCp composites under dry sliding condition

    Institute of Scientific and Technical Information of China (English)

    滕杰; 李华培; 陈刚

    2015-01-01

    Al-Si/15%SiCp (volume fraction) composites with different silicon contents were fabricated by spray deposition technique, and typical microstructures of these composites were studied by optical microscopy (OM). Dry sliding wear tests were carried out using a block-on-ring wear machine to investigate the effect of applied load range of 10−220 N on the wear and friction behavior of these composites sliding against SAE 52100 grade bearing steel. Scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDAX) were utilized to examine the morphologies of the worn surfaces in order to observe the wear characteristics and investigate the wear mechanism. The results show that the wear behavior of these composites is dependent on the silicon content in the matrix alloy and the applied load. Al-Si/15%SiCp composites with higher silicon content exhibit better wear resistance in the applied load range. Under lower loads, the major wear mechanisms are oxidation wear and abrasive wear for all tested composites. Under higher loads, severe adhesive wear becomes the main wear mechanisms for Al-7Si/15%SiCp and Al-13Si/15%SiCp composites, while Al-20Si/15%SiCp presents a compound wear mechanism, consisting of oxidation, abrasive wear and adhesion wear.

  1. Microstructural characteristics of in situ Mg2Si/Al-Si composite by low superheat pouring

    Directory of Open Access Journals (Sweden)

    Wu Xiaofeng

    2013-09-01

    Full Text Available To control the morphology and size of the primary and eutectic Mg2Si phases in in situ Mg2Si/Al-Si composite and achieve a feasible and reliable technique to produce appropriate feedstock for the thixo-casting and rheo-casting of this type of material, three Al-Si matrix composites reinforced by 5wt.%, 9wt.% and 17wt.% Mg2Si with hypoeutectic, eutectic and hypereutectic compositions were prepared by the low superheat pouring (LSP process. The effects of the pouring temperature (superheat on the morphology and size distribution of primary phases (primary α-Al and Mg2Si, binary (α-Al + Mg2Si eutectic cell and eutectic Mg2Si were investigated. The experimental results show that low pouring temperature (superheat not only refines the grain structure of the primary α-Al and binary (α-Al + Mg2Si eutectic cell in three composites and promotes the formation of more non-dendritic structural semi-solid metal (SSM slurry of these phases; but also refines the primary and eutectic Mg2Si phases, which seems to be attributed to the creation of an ideal condition for the nucleation and the acquisition of a high survival of nuclei caused by the LSP process.

  2. Refinement of primary Si grains in Al-20%Si alloy slurry through serpentine channel pouring process

    Science.gov (United States)

    Zheng, Zhi-kai; Mao, Wei-min; Liu, Zhi-yong; Wang, Dong; Yue, Rui

    2016-05-01

    In this study, a serpentine channel pouring process was used to prepare the semi-solid Al-20%Si alloy slurry and refine primary Si grains in the alloy. The effects of the pouring temperature, number of curves in the serpentine channel, and material of the serpentine channel on the size of primary Si grains in the semi-solid Al-20%Si alloy slurry were investigated. The results showed that the pouring temperature, number of the curves, and material of the channel strongly affected the size and distribution of the primary Si grains. The pouring temperature exerted the strongest effect, followed by the number of the curves and then the material of the channel. Under experimental conditions of a four-curve copper channel and a pouring temperature of 701°C, primary Si grains in the semi-solid Al-20%Si alloy slurry were refined to the greatest extent, and the lath-like grains were changed into granular grains. Moreover, the equivalent grain diameter and the average shape coefficient of primary Si grains in the satisfactory semi-solid Al-20%Si alloy slurry were 24.4 μm and 0.89, respectively. Finally, the refinement mechanism and distribution rule of primary Si grains in the slurry prepared through the serpentine channel pouring process were analyzed and discussed.

  3. Flexible micromorph tandem a-Si/μc-Si solar cells

    Science.gov (United States)

    Söderström, T.; Haug, F.-J.; Terrazzoni-Daudrix, V.; Ballif, C.

    2010-01-01

    The deposition of a stack of amorphous (a-Si:H) and microcrystalline (μc-Si:H) tandem thin film silicon solar cells (micromorph) requires at least twice the time used for a single junction a-Si:H cell. However, micromorph devices have a higher potential efficiency, thanks to the broader absorption spectrum of μc-Si:H material. High efficiencies can only be achieved by mitigating the nanocracks in the μc-Si:H cell and the light-induced degradation of the a-Si:H cell. As a result, μc-Si:H cell has to grow on a smooth substrate with large periodicity (>1 μm) and the a-Si:H cell on sharp pyramids with smaller feature size (˜350 nm) to strongly scatter the light in the weak absorption spectra of a-Si:H material. The asymmetric intermediate reflector introduced in this work uncouples the growth and light scattering issues of the tandem micromorph solar cells. The stabilized efficiency of the tandem n-i-p/n-i-p micromorph is increased by a relative 15% compared to a cell without AIR and 32% in relative compared to an a-Si:H single junction solar cells. The overall process (T cell deposited on polyethylene-naphthalate plastic substrate is 9.8% after 1000 h of light soaking at Voc, 1 sun, and 50 °C.

  4. Completely CMOS compatible SiN-waveguide-based fiber coupling structure for Si wire waveguides.

    Science.gov (United States)

    Maegami, Yuriko; Okano, Makoto; Cong, Guangwei; Ohno, Morifumi; Yamada, Koji

    2016-07-25

    For Si wire waveguides, we designed a highly efficient fiber coupling structure consisting of a Si inverted taper waveguide and a CMOS-compatible thin SiN waveguide with an SiO2 spacer inserted between them. By using a small SiN waveguide with a 310 nm-square core, the optical field can be expanded to correspond to a fiber with a 4.0-μm mode field diameter. A coupled waveguide system with the SiN waveguide and Si taper waveguide can provide low-loss and low-polarization-dependent mode conversion. Both losses in fiber-SiN waveguide coupling and SiN-Si waveguide mode conversion are no more than 1 dB in a wide wavelength bandwidth from 1.36 μm to 1.65 μm. Through a detailed analysis of the effective refractive indices in the coupled waveguide system, we can understand mode conversion accurately and also derive guidelines for reducing the polarization dependence and for shortening device length. PMID:27464137

  5. The roles of Eu during the growth of eutectic Si in Al-Si alloys

    Science.gov (United States)

    Li, Jiehua; Hage, Fredrik; Wiessner, Manfred; Romaner, Lorenz; Scheiber, Daniel; Sartory, Bernhard; Ramasse, Quentin; Schumacher, Peter

    2015-09-01

    Controlling the growth of eutectic Si and thereby modifying the eutectic Si from flake-like to fibrous is a key factor in improving the properties of Al-Si alloys. To date, it is generally accepted that the impurity-induced twinning (IIT) mechanism and the twin plane re-entrant edge (TPRE) mechanism as well as poisoning of the TPRE mechanism are valid under certain conditions. However, IIT, TPRE or poisoning of the TPRE mechanism cannot be used to interpret all observations. Here, we report an atomic-scale experimental and theoretical investigation on the roles of Eu during the growth of eutectic Si in Al-Si alloys. Both experimental and theoretical investigations reveal three different roles: (i) the adsorption at the intersection of Si facets, inducing IIT mechanism, (ii) the adsorption at the twin plane re-entrant edge, inducing TPRE mechanism or poisoning of the TPRE mechanism, and (iii) the segregation ahead of the growing Si twins, inducing a solute entrainment within eutectic Si. This investigation not only demonstrates a direct experimental support to the well-accepted poisoning of the TPRE and IIT mechanisms, but also provides a full picture about the roles of Eu atoms during the growth of eutectic Si, including the solute entrainment within eutectic Si.

  6. Un concepto sobre las redes de conocimiento entre organizaciones

    Directory of Open Access Journals (Sweden)

    Lorena Gutiérrez González

    2011-01-01

    Full Text Available En América Latina, los intercambios que se generan entre las organizaciones académicas e industriales son escasos y generalmente no implican la transferencia de innovaciones tecnológicas. Por tal motivo, se considera que para alcanzar una completa explicación de estas relaciones, deben generarse aportes propios, acordes con nuestra realidad socio-económica. Considerando lo anterior, en esta investigación, se procura construir un concepto sobre las redes de conocimiento entre organizaciones. Para ello, se recurrió a un método para generar teoría propuesto por Gutiérrez (2009, el cual se sustenta en el engranaje del método hermenéutico (Dilthey, 1990, la técnica de análisis cualitativo de contenido (Kockelmans, 1975, la abducción (Barrena, 2007 y los criterios establecidos por Rudner (1973 para la construcción de la teoría social. Los resultados destacan la elaboración de un esquema analítico-conceptual, a través del cual se esboza a las redes de conocimiento como un sistema de relaciones organizacionales que se establecen para el fomento del desarrollo endógeno local, la inclusión social y la sustentabilidad. Tal fundamento teórico fue generado a través de un proceso inventivo signado por el rigor de un método científico así como, por la espontaneidad del instinto creativo.

  7. Fabrication of poly-crystalline Si-based Mie resonators via amorphous Si on SiO2 dewetting

    Science.gov (United States)

    Naffouti, Meher; David, Thomas; Benkouider, Abdelmalek; Favre, Luc; Ronda, Antoine; Berbezier, Isabelle; Bidault, Sebastien; Bonod, Nicolas; Abbarchi, Marco

    2016-01-01

    We report the fabrication of Si-based dielectric Mie resonators via a low cost process based on solid-state dewetting of ultra-thin amorphous Si on SiO2. We investigate the dewetting dynamics of a few nanometer sized layers annealed at high temperature to form submicrometric Si-particles. Morphological and structural characterization reveal the polycrystalline nature of the semiconductor matrix as well as rather irregular morphologies of the dewetted islands. Optical dark field imaging and spectroscopy measurements of the single islands reveal pronounced resonant scattering at visible frequencies. The linewidth of the low-order modes can be ~20 nm in full width at half maximum, leading to a quality factor Q exceeding 25. These values reach the state-of-the-art ones obtained for monocrystalline Mie resonators. The simplicity of the dewetting process and its cost-effectiveness opens the route to exploiting it over large scales for applications in silicon-based photonics.

  8. Pattern formation in SiSb system

    OpenAIRE

    Csik, A.; Erdelyi, G.; Langer, G A; Daroczi, L.; Beke, D. L.; Nyeki, J.; Erdelyi, Z.

    2009-01-01

    Thermal annealing of Si/Si1-xSbx/Si amorphous thin film tri-layer samples (x=18 and 24 at%Sb) under 100 bar Ar pressure results in an interesting pattern formation. In pictures, taken by means of cross-sectional transmission electron microscopy (TEM), stripe-shaped contrast, with three maxima, parallel with the interfaces can be seen. Secondary neutral mass spectrometer (SNMS) measurements revealed that the regions with different contrasts correspond to Sb-rich and Sb-depleted regions. Furthe...

  9. Size and Location Control of Si Nanocrystals at Ion Beam Synthesis in Thin SiO2 Films

    OpenAIRE

    Mueller, Torsten; Heinig, Karl-Heinz; Moeller, Wolfhard

    2002-01-01

    Binary collision simulations of high-fluence 1 keV Si ion implantation into 8 nm thick SiO2 films on (001)Si were combined with kinetic Monte Carlo simulations of Si nanocrystal (NC) formation by phase separation during annealing. For nonvolatile memory applications, these simulations help to control size and location of NCs. For low concentrations of implanted Si, NCs form via nucleation, growth and Ostwald ripening, whereas for high concentrations Si separates by spinodal decomposition. In ...

  10. Removal of C and SiC from Si and FeSi during ladle refining and solidification

    Energy Technology Data Exchange (ETDEWEB)

    Klevan, Ole Svein

    1997-12-31

    The utilization of solar energy by means of solar cells requires the Si to be very pure. The purity of Si is important for other applications as well. This thesis mainly studies the total removal of carbon from silicon and ferrosilicon. The decarburization includes removal of SiC particles by stirring and during casting in addition to reduction of dissolved carbon by gas purging. It was found that for three commercial qualities of FeSi75, Refined, Gransil, and Standard lumpy, the refined quality is lowest in carbon, followed by Gransil and Standard. A decarburization model was developed that shows the carbon removal by oxidation of dissolved carbon to be a slow process at atmospheric pressure. Gas stirring experiments have shown that silicon carbide particles are removed by transfer to the ladle wall. The casting method of ferrosilicon has a strong influence on the final total carbon content in the commercial alloy. Shipped refined FeSi contains about 100 ppm total carbon, while the molten alloy contains roughly 200 ppm. The total carbon out of the FeSi-furnace is about 1000 ppm. It is suggested that low values of carbon could be obtained on an industrial scale by injection of silica combined with the use of vacuum. Also, the casting system could be designed to give low carbon in part of the product. 122 refs., 50 figs., 24 tabs.

  11. Impact of Ge content on the gate oxide reliability of strained-Si/SiGe MOS devices

    Energy Technology Data Exchange (ETDEWEB)

    Uppal, Suresh [School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU (United Kingdom)]. E-mail: Suresh.uppal@newcastle.ac.uk; Kanoun, Mehdi [School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU (United Kingdom); Varzgar, John B. [School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU (United Kingdom); Chattopadhyay, Sanatan [School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU (United Kingdom); Olsen, Sarah [School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU (United Kingdom); O' Neill, Anthony [School of Electrical, Electronic and Computer Engineering, Merz Court, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU (United Kingdom)

    2006-12-15

    In this paper we study the impact of the variation of Ge content on the gate oxide reliability of strained-Si/SiGe (s-Si/SiGe) MOS devices. MOS capacitors and n-MOSFET devices were fabricated on Si, and strained Si grown on SiGe virtual substrates with a Ge content of 10 and 30%. The devices had poly-Si gates and were fabricated using thermal oxidation at 800 deg. C giving average oxide thickness of 6.8 nm. Constant voltage stressing (CVS) at 7 V was used to study the breakdown characteristics of different samples. We observe a distinguishably different breakdown phenomenon for Si and s-Si/SiGe samples. Whereas the oxide on Si shows a typical breakdown behavior of a thick oxide, the oxide on s-Si/SiGe samples showed a quasi- or soft breakdown with an abrupt increase in gate leakage which increases after further stressing. The time to breakdown decreased with increase in the Ge content. These behaviors are attributed to poorer quality of the oxide on s-Si/SiGe caused by the high surface roughness, interface and oxide charges. It is pointed that quasi-breakdown may be a stronger reliability limiting factor for s-Si/SiGe devices in the oxide thickness range studied.

  12. Relação entre mudança organizacional e implantação de Sistemas de Informações: um estudo no setor de autopeças

    Directory of Open Access Journals (Sweden)

    Silveira Marco Antonio Pinheiro da

    2002-01-01

    Full Text Available Este trabalho discute a relação entre a implantação de Sistemas de Informações (SI e processos de mudança organizacional. Considerou-se que essa relação pode ser estudada a partir de dois enfoques: tecnológico ou organizacional. O enfoque tecnológico considera a implantação de SI como um elemento desencadeador da mudança, enquanto no enfoque organizacional os SI ocupariam papel secundário. Foram realizadas entrevistas com 27 executivos de 5 empresas de autopeças, observando-se como os processos de mudança estão relacionados com a implantação de SI. O trabalho conclui que nessas empresas o enfoque organizacional é predominante, porém, identificam-se situações em que a implantação de SI tem papel e importância distintos na mudança organizacional.

  13. La relación entre la capacidad de atencion dividida y la estimación prospectiva del tiempo

    Directory of Open Access Journals (Sweden)

    Susana Celeste Azzollini

    2004-01-01

    Full Text Available Se realizó una investigación cuyo objetivo fue determinar si la capacidad de atención dividida resultaba explicativa de la variabilidad de las estimaciones prospectivas del tiempo. Los modelos teóricos sobre dicha estimación postulan que los recursos atencionales de procesamiento están divididos entre un procesador temporal, que cuenta y almacena unidades temporales subjetivas (Subjective Temporal Units - STUs y otras actividades de procesamiento no temporal (Zakay, 1993. Se seleccionó una muestra de 36 estudiantes universitarios que fueron asignados al azar a cada una de las seis condiciones experimentales, determinadas por un diseño factorial 3 x 2, y sus factores básicos fueron: cantidad de tareas y niveles de complejidad del material. Se confeccionaron materiales para las diferentes tareas y otros con el fin de evaluar las aptitudes mnémicas y la capacidad de atención dividida. Se solicitó a los sujetos que mientras realizaban las tareas, detuvieran un cronómetro cuando consideraran que había pasado un período de tiempo predeterminado. La estimación del tiempo se calculó por la diferencia en segundos entre el tiempo real y el tiempo estimado. Los datos se procesaron con análisis de correlación, discriminante y factorial de variancia. Los resultados obtenidos indican que la capacidad de atención dividida se correlaciona con la estimación temporal prospectiva y además, la capacidad de atención dividida resulta un buen predictor de la capacidad estimativa de los sujetos, especialmente de los sobre-estimadores. Las diferencias en las aptitudes mnémicas no explicaron la variabilidad de las estimaciones prospectivas.

  14. Variación antropométrica y nutricional en Susques y Alto Comedero entre 2002-2007

    Directory of Open Access Journals (Sweden)

    Bejarano, Ignacio

    2007-01-01

    Full Text Available Las poblaciones humanas experimentan variaciones de los parámetros antropométricos como expresión de los cambios socioambientales. El objetivo de este trabajo fue analizar la variación temporal de talla, peso y estado nutricional en dos poblaciones jujeñas situadas a distintos niveles altitudinales. Los datos procedieron de mediciones realizadas en 2002 y 2007 en poblaciones de 6 a 17 años de Susques (3500 m y Alto Comedero (1200 m. Se calcularon las categorías nutricionales de Waterlow y las diferencias entre talla y peso y categorías nutricionales se establecieron con ANOVA y prueba de comparación de proporciones (χ2 respectivamente. Para ambas poblaciones se observaron diferencias interanuales estadísticamente significativas de los promedios de talla y peso, siendo menores en Susques en el 2007, lo contrario sucede en Alto Comedero. Las diferencias interanuales de la categorías nutricionales no fueron estadísticamente significativas en Alto Comedero, pero si en Susques para normonutridos y obesos que disminuyeron y aumentaron respectivamente entre 2002 y 2007. En el contexto de las modificaciones socioeconómicas experimentadas por la población susqueña en los últimos años, debido a su mayor conexión e integración con poblaciones vecinas por la apertura del Paso de Jama, los resultados indicarían un empeoramiento de las condiciones nutricionales de su población infanto juvenil.

  15. Movimientos entre cultura escolar y cultura científica: análisis de argumentos en diferentes contextos

    Directory of Open Access Journals (Sweden)

    Daniela Lopes-Scarpa

    2013-01-01

    Full Text Available Para investigar relaciones entre cultura científica y cultura escolar, se analizan las características del argumento enun - ciado en textos científicos y en producciones de alumnos de educación básica. Se usó el patrón del argumento de t oulmin y marcas lingüísticas. El análisis mostró que los alumnos ha - cen argumentos substanciales y que los argumentos científi - cos son analíticos. La utilización diferenciada de los tiempos verbales del discurso sugiere la transformación de la Biología Funcional en narrativa histórica. La selección lexical y el uso de calificadores evidenciaron la presencia de modalidades aléti - cas y epistémicas que asumieron funciones diferenciadas. Ese análisis plantea consideraciones sobre el carácter híbrido de la enseñanza de las ciencias.Los análisis y reflexiones emprendidos en este artículo contri - buyen a las discusiones sobre los objetivos de la enseñanza de las ciencias. Proponemos que el objetivo de la enseñanza de ciencias es un diálogo entre culturas, de forma que los interlocutores tomen una actitud de respuesta ante el cono - cimiento. Si se asumen la argumentación y la práctica de la justificación como centrales en la formación de comunidades comunicacionales y en la construcción de la subjetividad críti - ca, comprender las características del argumento puede con - tribuir a las investigaciones sobre enseñanza de las ciencias, con miras a investigar y desarrollar habilidades involucradas en la argumentación.

  16. Preparation and Characterization of Novel Porous Fe-Si Alloys

    Institute of Scientific and Technical Information of China (English)

    WANG Jiefeng; HE Yuehui; JIANG Yao; GAO Hanyan; YANG Junsheng; GAO Lin

    2016-01-01

    Porous Fe-Si alloys with different nominal compositions ranging from Fe-10wt% Si to Fe-50wt% Si were fabricated through a reactive synthesis of Fe and Si elemental powder mixtures. The effects of Si contents on the pore structure of porous Fe-Si alloy were investigated in detail. The results showed that the open porosity, gas permeability and maximum pore size of the porous Fe-Si alloys increased with increasing Si contents, indicating that the porosity and pore size can be tailored by changing the Si contents. The pore structure parameter including the open porosity, gas permeability, maximum pore size obeyed the Hagen-Poiseuille formula with the constant G=0.035 m-1Pa-1s-1 for the reactively synthesized porous Fe-Si alloys. The mechanical property of the porous Fe-Si alloys showed applicability in the ifltration industries.

  17. Villa Elisa Rice Cooperative, a good example of Entre Rios cooperative tradition (Argentina La Cooperativa Arroceros Villa Elisa, un buen ejemplo de la tradición cooperativista de Entre Ríos (Argentina

    Directory of Open Access Journals (Sweden)

    Graciela Mateo

    2011-01-01

    Full Text Available Historians recognize Entre Rios province as the birthplace of colonization but it is also there that, since the beginning of the twentieth century, agricultural cooperatives providing important services to partners in sourcing, marketing and industrialization have developed. Cooperative aid have brought about a more rational use of the land, increased turnover, improved product quality, efficient use of capital and rising demand due to expanding markets, different services that each farmer by itself could not reach. This article proposes to analyse the trajectory of a rice producers cooperative -founded in the 1970's - located in the town of Villa Elisa, Entre Rios province, which in greater or lesser degree has been giving these benefits and ranks nowadays as the third national rice exporter and occupies the first place in cooperative management. As well as economic issues, particular attention will be given to the institutional articulation of the company and the introduccion of organizational changes.Así como la Historia reconoce a Entre Ríos como cuna de la colonización, es también en esta provincia donde desde el comienzo del siglo XX se desarrolla el cooperativismo agrario que presta importantes servicios al asociado en materia de abastecimiento, comercialización y transformación. Prestación que se traduce en un uso más racional de la tierra, un mayor volumen de negocios, el mejoramiento en la calidad del producto, la utilización eficiente del capital, el aumento de la demanda por la ampliación de los mercados y la introducción de servicios que cada agricultor por si sólo no podría alcanzar. El presente artículo se propone analizar la trayectoria de una cooperativa arrocera -fundada en la década de 1970- ubicada en la localidad entrerriana de Villa Elisa que en mayor o menor media ha ido cumpliendo con esas prestaciones y que hoy se posiciona como el tercer exportador nacional de arroz y el primero de gestión cooperativa

  18. Fabrication of c-Si:H(p)/c-Si(n) Heterojunction Solar Cells with Microcrystalline Emitters

    Institute of Scientific and Technical Information of China (English)

    ZHOU Bing-Qing; LIU Feng-Zhen; ZHANG Qun-Fang; XU Ying; ZHOU Yu-Qin; LIU Jin-Long; ZHU Mei-Fang

    2006-01-01

    The p-type microcrystalline silicon (fj,c-Si) on n-type crystalline silicon (c-Si) heterojunction solar cells is fabricated by radio-frequency plasma enhanced chemical vapour deposition (rf-PECVD). The effect of the pc-Si:H p-layers on the performance of the heterojunction solar cells is investigated. Optimum μcSi:H p-layer is obtained with hydrogen dilution ratio of 99.65%, rf-power of 0.08 W/cm2, gas phase doping ratio of 0.125%, and the p-layer thickness of 15 nm. We fabricate μc-Si:H(p)/c-Si(n) heterojunction solar cells without texturing and obtained an efficiency of 13.4%. The comparisons of the solar-cell performances using different surface passivation techniques are discussed.

  19. Structure and chemistry of passivated SiC/SiO2 interfaces

    Science.gov (United States)

    Houston Dycus, J.; Xu, Weizong; Lichtenwalner, Daniel J.; Hull, Brett; Palmour, John W.; LeBeau, James M.

    2016-05-01

    Here, we report on the chemistry and structure of 4H-SiC/SiO2 interfaces passivated either by nitric oxide annealing or Ba deposition. Using aberration corrected scanning transmission electron microscopy and spectroscopy, we find that Ba and N remain localized at SiC/SiO2 interface after processing. Further, we find that the passivating species can introduce significant changes to the near-interface atomic structure of SiC. Specifically, we quantify significant strain for nitric oxide annealed sample where Si dangling bonds are capped by N. In contrast, strain is not observed at the interface of the Ba treated samples. Finally, we place these results in the context of field effect mobility.

  20. SiC/SiC fuel cladding R and D Project 'SCARLET': Status and future plan

    International Nuclear Information System (INIS)

    This paper provides the recent progress in SiC/SiC development towards early utilisation for LWRs based on NITE method. After the March 11 Disaster in East-Japan, ensuring safe technology for LWR became a top priority R and D in nuclear energy policy of Japan. Along this line, replacement of Zircaloy claddings with SiC/SiC based fuel cladding is becoming one of the most attractive options and a MEXT fund based project, SCARLET, and a METI fund based project have been launched as 5-year termed projects at Muroran Institute of Technology. These projects care for NITE process for making long SiC/SiC fuel pins and connecting technology integration. The SCARLET project also includes coolant compatibility and irradiation effect evaluations as LWR and LMFBR materials. The outline and the present status of the SCARLET project will be briefly introduced in the present paper. (authors)