943 resultados para Super-redes Hubbard - Multicamadas magnéticas


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Three new supramolecular assemblies of co-crystallized metal complexes and aliphatic dicarboxylic acids, {[Cu(pic)(2)(H2O)(2)](H(2)mal)}(n) (1), {[Cu(pic)(2)(H2O)(2)](H(2)mal)(2)(H2O)(2)}(n) (2) and {[Cu(pic)(2)(MeOH)](H(2)succ)}(n) (3) {Hpic = 2-picolinic acid, H(2)mal = malonic acid and H(2)succ = succinic acid} have been synthesized and characterized by X-ray single-crystal structure determination. The crystal packings of the complexes reveal that supramolecular associations of the monomeric complex units lead to the formation of layers through hydrogen bonding. In all the complexes, the dicarboxylic acid units connect the 2-D layers to act as pillars. The interaction between water molecules and the dicarboxylic acid plays an important role in the overall supramolecular assembly. (C) 2008 Elsevier Ltd. All rights reserved.

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Esta dissertação analisa os diálogos no Facebook, no perfil do Hemorio, o hemocentro do Estado do Rio de Janeiro, durante duas situações de crise, ambas no ano de 2011: as chuvas na Região Serrana do Rio de Janeiro e o ataque da Escola Municipal Tasso da Silveira, em Realengo. Embora estes períodos registrem aumento de mais de 400% nas doações de sangue voluntárias no Hemorio, não se buscou comprovar a \2018veracidade\2019 dos depoimentos ou mensurar a correlação entre as postagens e a doação efetiva. Nosso objetivo maior foi o de identificar os sentidos associados à doação de sangue, as motivações, as relações de troca e os sentimentos, tal como manifestos na mídia digital. Para alargar a compreensão do universo no qual o ato de doar está inscrito, utilizamos os estudos teóricos sobre a dádiva \2013 tanto o trabalho seminal de Marcel Mauss, o \201CEnsaio sobre a Dádiva\201D, como de autores contemporâneos, como Alain Caillé, Jacques Godbout, Paulo Henrique Martins e Alda Lacerda. Esta vertente foi conjugada com as teorias de redes sociais online (Henry Jenkins, Pierre Lévy, Mark Granovetter, Manuel Castells e Raquel Recuero), explorando as conexões entre a tríade \201Cdar, receber e retribuir\201D, como forma de estabelecer as relações sociais, e o universo digital

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Voluminous rhyolitic eruptions from Toba, Indonesia, and Taupo Volcanic Zone (TVZ), New Zealand, have dispersed volcanic ash over vast areas in the late Quaternary. The ~74 ka Youngest Toba Tuff (YTT) eruption deposited ash over the Bay of Bengal and the Indian subcontinent to the west. The ~340 ka Whakamaru eruption (TVZ) deposited the widespread Rangitawa Tephra, dominantly to the southeast (in addition to occurrences northwest of vent), extending across the landmass of New Zealand, and the South Pacific Ocean and Tasman Sea, with distal terrestrial exposures on the Chatham Islands. These super-eruptions involved ~2500 km^3 and ~1500 km3 of magma (dense-rock equivalent; DRE), respectively. Ultra-distal terrestrial exposures of YTT at two localities in India, Middle Son Valley, Madhya Pradesh, and Jurreru River Valley, Andhra Pradesh, at distances of >2000 km from the source caldera, show a basal ‘primary’ ashfall unit ~4 cm thick, although deposits containing reworked ash are up to ~3 m in total thickness. Exposures of Rangitawa Tephra on the Chatham Islands, >900 km from the source caldera, are ~15-30 cm thick. At more proximal localities (~200 km from source), Rangitawa Tephra is ~55-70 cm thick and characterized by a crystal-rich basal layer and normal grading. Both distal tephra deposits are characterized by very-fine ash (with high PM10 fractions) and are crystal-poor. Glass chemistry, stratigraphy and grain-size data for these distal tephra deposits are presented with comparisons of their correlation, dispersal and preservation. Using field observations, ash transport and deposition were modeled for both eruptions using a semi-analytical model (HAZMAP), with assumptions concerning average wind direction and strength during eruption, column shape and vent size. Model outputs provide new insights into eruption dynamics and better estimates of eruption volumes associ- ated with tephra fallout. Modeling based on observed YTT distal tephra thicknesses indicate a relatively low (<40 km high), very turbulent eruption column, consistent with deposition from a co-ignimbrite cloud extending over a broad region. Similarly, the Whakamaru eruption was modeled as producing a predominantly Plinian column (~45 km high), with dispersal to the southeast by strong prevailing winds. Significant ash fallout of the main dispersal direction, to the northwest of source, cannot be replicated in this modeling. The widespread dispersal of large volumes of fine ash from both eruptions may have had global environmental consequences, acutely affecting areas up to thousands of kilometers from vent.

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The results of applying a fragment-based protein tertiary structure prediction method to the prediction of 14 CASP5 target domains are described. The method is based on the assembly of supersecondary structural fragments taken from highly resolved protein structures using a simulated annealing algorithm. A number of good predictions for proteins with novel folds were produced, although not always as the first model. For two fold recognition targets, FRAGFOLD produced the most accurate model in both cases, despite the fact that the predictions were not based on a template structure. Although clear progress has been made in improving FRAGFOLD since CASP4, the ranking of final models still seems to be the main problem that needs to be addressed before the next CASP experiment

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1] We apply a novel computational approach to assess, for the first time, volcanic ash dispersal during the Campanian Ignimbrite (Italy) super-eruption providing insights into eruption dynamics and the impact of this gigantic event. The method uses a 3D time-dependent computational ash dispersion model, a set of wind fields, and more than 100 thickness measurements of the CI tephra deposit. Results reveal that the CI eruption dispersed 250–300 km3 of ash over ∼3.7 million km2. The injection of such a large quantity of ash (and volatiles) into the atmosphere would have caused a volcanic winter during the Heinrich Event 4, the coldest and driest climatic episode of the Last Glacial period. Fluorine-bearing leachate from the volcanic ash and acid rain would have further affected food sources and severely impacted Late Middle-Early Upper Paleolithic groups in Southern and Eastern Europe

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We investigate the super-Brownian motion with a single point source in dimensions 2 and 3 as constructed by Fleischmann and Mueller in 2004. Using analytic facts we derive the long time behavior of the mean in dimension 2 and 3 thereby complementing previous work of Fleischmann, Mueller and Vogt. Using spectral theory and martingale arguments we prove a version of the strong law of large numbers for the two dimensional superprocess with a single point source and finite variance.

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The search for rocky exoplanets plays an important role in our quest for extra-terrestrial life. Here, we discuss the extreme physical properties possible for the first characterised rocky super-Earth, CoRoT-7b (R(pl) = 1.58 +/- 0.10 R(Earth), M(pl) = 6.9 +/- 1.2 M(Earth)). It is extremely close to its star (a = 0.0171 AU = 4.48 R(st)), with its spin and orbital rotation likely synchronised. The comparison of its location in the (M(pl), R(pl)) plane with the predictions of planetary models for different compositions points to an Earth-like composition, even if the error bars of the measured quantities and the partial degeneracy of the models prevent a definitive conclusion. The proximity to its star provides an additional constraint on the model. It implies a high extreme-UV flux and particle wind, and the corresponding efficient erosion of the planetary atmosphere especially for volatile species including water. Consequently, we make the working hypothesis that the planet is rocky with no volatiles in its atmosphere, and derive the physical properties that result. As a consequence, the atmosphere is made of rocky vapours with a very low pressure (P <= 1.5 Pa), no cloud can be sustained, and no thermalisation of the planet is expected. The dayside is very hot (2474 +/- 71 K at the sub-stellar point) while the nightside is very cold (50-75 K). The sub-stellar point is as hot as the tungsten filament of an incandescent bulb, resulting in the melting and distillation of silicate rocks and the formation of a lava ocean. These possible features of CoRoT-7b could be common to many small and hot planets, including the recently discovered Kepler-10b. They define a new class of objects that we propose to name ""Lava-ocean planets"". (C) 2011 Elsevier Inc. All rights reserved.

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We investigate the combined influence of quenched randomness and dissipation on a quantum critical point with O(N) order-parameter symmetry. Utilizing a strong-disorder renormalization group, we determine the critical behavior in one space dimension exactly. For super-ohmic dissipation, we find a Kosterlitz-Thouless type transition with conventional (power-law) dynamical scaling. The dynamical critical exponent depends on the spectral density of the dissipative baths. We also discuss the Griffiths singularities, and we determine observables.

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This essay examines the persuasive side of language in a speech given by Senator Barack Obama on Super Tuesday in February 2008. It studies how Senator Obama utilizes language to convince and persuade his audience. This is done from an Aristotelian point of view, meaning that the study focuses foremost on how the senator’s word choices relate to Aristotle’s three means of persuasion, ethos, pathos and logos. Those basic guiding principles are relevant to use since Aristotle’s work on the subject of rhetoric is still today one of the most relevant works in that field. The analysis is basically performed through personal observations guided by previous studies, within the frame of Aristotelian rhetoric. The results show how Senator Obama enforces the three means of persuasion through language and how it can be considered persuasive. The study might add to rhetoric studies from a linguistic perspective since it reaches a better understanding of language used in the field of politics, where rhetoric is a prominent component.

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Valendo-me das categorias da Economia das trocas simbólicas, propostas por Bourdieu, pretendo desenvolver neste artigo uma breve análise das trocas simbólicas produzidas em um novo ambiente sócio-técnico (a internet) e como ele tornou possível o surgimento de um espaço virtual de coalizões (redes de interagentes). Nesse sentido, torna-se fundamental pensar a complexa integração entre as trocas simbólicas no mundo "off-line" e "on-line" que disputam o acesso à produção, apropriação e distribuição universal de novos tipos de recursos mais ou menos escassos. Procuro analisar,brevemente, a relação entre a promessa de abundância e certos tipos de escassez encontrados no ciberespaço e a colocação de uma questão que considero fundamental: a arquitetura distribuída da rede eliminaria totalmente a necessidade de representação e delegação ou estabeleceria diferentes filtros e modalidades de organização e seleção de porta-vozes em novos tipos de comunidades?

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Dissertação (Mestrado em Administração - Área de Concentração: Gestão de Redes Organizacionais)-USCS, São Caetano do Sul, 2010.

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Dissertação apresentada ao Programa de Mestrado em Administração da Universidade Municipal de São Caetano do Sul - USCS

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El objetivo de esta investigación es registrar la producción académica reciente sobre el uso de las redes sociales como herramientas de comunicación, educación y aprendizaje en el área de la salud, con énfasis en la red social Facebook. La investigación fue recolectada sobre la base de datos del Portal de revistas de Capes, utilizando las palabras clave "Facebook, educación y salud", teniendo como criterio de búsqueda el uso de contenido de acceso abierto más actual, publicado durante el período comprendido entre 2005 y 2011. El estudio señaló 37 trabajos científicos sobre el tema estudiado, 2 brasileños y 35 internacionales.

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Dissertação apresentada ao Programa de Mestrado em Comunicação da Universidade Municipal de São Caetano do Sul - USCS