555 resultados para Gan
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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A partir de uma seleção de dezesseis poemas metalinguísticos dos livros Liturgia da Matéria (1982), Mínima Lírica (1989), Trovar Claro (1997), Macau (2003), Tarde (2007) e Formas do Nada (2012) pretendeu-se chegar ao que se chama aqui de A Poética de Paulo Henriques Britto. Tal poética compreende as características e temas mais frequentes em sua poesia, bem como quais recursos expressivos são mais evidentes em cada um dos livros. Paulo Henriques Britto, tradutor, professor e escritor com sete livros publicados (sendo um deles de contos), lançou seu primeiro livro de poesias, Liturgia da Matéria, em 1982 e vem ganhando destaque no cenário da poesia brasileira contemporânea. Em 2004 ganhou um dos maiores prêmios literários do Brasil, o Prêmio Portugal Telecom, com o livro Macau lançado em 2003. Pretende-se que o estudo aqui feito acerca da poesia de Britto não fique restrito a si, mas que traga contribuições para a crítica da poesia brasileira contemporânea, já que ainda se carece de uma quantidade de material critico relevante, o que muitas vezes dificulta o ensino e a aprendizagem de tal poesia. Assim, a análise da poesia metalinguística de Paulo Henriques Britto pretende descobrir, em parte, quais os novos rumos que a produção de poesia tomou no Brasil. Nosso corpus é composto por dezesseis poemas, sendo eles: “I”, da série “Dez Sonetos Sentimentais”, “III”, da série “Três Lamentos” e “Profissão de Fé” do livro Liturgia da Matéria; “I” e “II”, da série “Minima Poética” do livro Mínima Lírica; “II” e “VII” da série “Sete Estudos para a Mão Esquerda” e “Sonetilho de Verão” do livro Trovar Claro; “II” da série “Fisiologia da Composição” e “Biodiversidade” do livro Macau; “I” e “II” da série “Art Poétique” e “5” da série “Crepuscular” do livro Tarde e “I” e “III” da série “Oficina” e o poema “Pós” do ...
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Perioperative fluid therapy remains a highly debated topic. Its purpose is to maintain or restore effective circulating blood volume during the immediate perioperative period. Maintaining effective circulating blood volume and pressure are key components of assuring adequate organ perfusion while avoiding the risks associated with either organ hypo- or hyperperfusion. Relative to perioperative fluid therapy, three inescapable conclusions exist: overhydration is bad, underhydration is bad, and what we assume about the fluid status of our patients may be incorrect. There is wide variability of practice, both between individuals and institutions. The aims of this paper are to clearly define the risks and benefits of fluid choices within the perioperative space, to describe current evidence-based methodologies for their administration, and ultimately to reduce the variability with which perioperative fluids are administered. Based on the abovementioned acknowledgements, a group of 72 researchers, well known within the field of fluid resuscitation, were invited, via email, to attend a meeting that was held in Chicago in 2011 to discuss perioperative fluid therapy. From the 72 invitees, 14 researchers representing 7 countries attended, and thus, the international Fluid Optimization Group (FOG) came into existence. These researches, working collaboratively, have reviewed the data from 162 different fluid resuscitation papers including both operative and intensive care unit populations. This manuscript is the result of 3 years of evidence-based, discussions, analysis, and synthesis of the currently known risks and benefits of individual fluids and the best methods for administering them. The results of this review paper provide an overview of the components of an effective perioperative fluid administration plan and address both the physiologic principles and outcomes of fluid administration. We recommend that both perioperative fluid choice and therapy be individualized. Patients should receive fluid therapy guided by predefined physiologic targets. Specifically, fluids should be administered when patients require augmentation of their perfusion and are also volume responsive. This paper provides a general approach to fluid therapy and practical recommendations.
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Drug addiction won dramatic aspects in terms of its dimensions and the effects that it imposes. These chemical agents are able to reduce the immune reactivity and tissue repair, and enhance microbial aggression, aggravating the destruction of the periodontium and other side effects. This study aimed to evaluate the presence of key periodontal pathogens in the mouth of drug addiction patients, comparing it with individuals who do not exhibit this dependence, as well as assess the influence of oral conditions on the occurrence of such microorganisms. For this purpose, data on systemic health conditions, socioeconomic, patterns of licit or illicit drug consumption of 100 patients with chemical dependency kept in rehabilitation clinics and an equal number of non-dependent patients, who formed the control group were obtained. Intra and extraoral clinical examinations were performed and samples of supragingival and subgingival biofilm, saliva and mucous membranes were collected. The presence of the targeted microorganism was assessed by polymerase chain reaction (PCR). It was found that Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola showed close correlation with bone loss and gingival bleeding in drug addiction dependents and control group, but the oral mucous membranes and saliva of addicts showed higher occurrence of these pathogens.
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La popularización de los medios digitales y los recursos de comunicación difunde las narrativas no lineales y agrava la crisis de la enseñanza en el aula, con la expansión de diferentes modelos presenciales virtuales de la educación (PVE). Es evidente la demasificación de los nuevos medios, en un contexto que agudiza la percepción individual y social de los individuos, que son atraídos por el enorme flujo global de mensajes informativos (BRIGGS; BURKE, 2006). La transición de los métodos de enseñanza en el aula para modelar la educación virtual e interactiva ganó un nuevo formato en la educación pública en São Paulo en 2012, con el lanzamiento de cursos electivos de enseñanza de Inglés y Español para estudiantes de la secundaria, con la mediación de el PC y con el contenido producido por la Escuela Virtual de Programas Educativos del Estado de São Paulo - Evesp. Aún continua presencia en los salones de las grandes clases del sistema escolar, la falta de materiales de enseñanza y aprendizaje adecuados en las clases impartidas por los profesores cuyos repertorios están alejados de la vida cotidiana de los estudiantes. En este contexto, se comprueban las actuaciones de aprendizaje cualitativos más bien negativos de las cuatro habilidades comunicativas: escuchar, hablar, leer y escribir (CAMERON, 2001). La investigación que llevamos a cabo es analizar las experiencias de enseñanza de Inglés y Español en la plataforma computarizada Evesp y de la clase de Inglés y Español de los Centros para el Curso de idiomas (CELS), para la escuela secundaria, y el piloto Early Bird, de enseñanza y el aprendizaje de Inglés de la escuela primaria, todos bajo la Junta de Educación de Bauru (SP).
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Background: Antibodies directed against endothelial cell surface antigens have been described in many disorders and have been associated with disease activity. Since the most prominent histopathologic feature in mixed connective tissue disease (MCTD) is the widespread and unique proliferative vascular lesion, our aim was to evaluate the frequency of anti-endothelial cell antibodies (AECA) in this condition. Objectives: To evaluate the frequency of AECA in this disease and assess its clinical and laboratory associations. Methods: Seventy-three sera from 35 patients with MCTD (Kasukawa's criteria), collected during a 7 year period, were tested for immunoglobulins G and M (IgG and IgM) AECA by cellular ELISA, using HUVEC (human umbilical vein endothelial cells). Sera from 37 patients with systemic lupus erythematosus (SLE), 22 with systemic sclerosis (SSc) and 36 sera from normal healthy individuals were used as controls. A cellular ELISA using HeLa cells was also performed as a laboratory control method. Results: IgG-AECA was detected in 77% of MCTD patients, 54% of SLE patients, 36% of SSc patients and 6% of normal controls. In MCTD, IgG-AECA was associated with vasculitic manifestations, disease activity and lymphopenia, and was also a predictor of constant disease activity. Immunosuppressive drugs were shown to reduce IgG-AECA titers. Since antibodies directed to HeLa cell surface were negative, AECA was apparently unrelated to common epitopes present on epithelial cell lines. Conclusions: AECA are present in a large proportion of patients with MCTD and these antibodies decrease after immunosuppressive treatment. IMAJ 2012; 14:84-87
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Semiconductor nanowhiskers (NWs) made of III-V compounds exhibit great potential for technological applications. Controlling the growth conditions, such as temperature and diameter, it is possible to alternate between zinc-blende (ZB) and wurtzite (WZ) crystalline phases, giving origin to the so called polytypism. This effect has great influence in the electronic and optical properties of the system, generating new forms of confinement to the carriers. A theoretical model capable to accurately describe electronic and optical properties in these polytypical nanostructures can be used to study and develop new kinds of nanodevices. In this study, we present the development of a wurtzite/zinc-blende polytypical model to calculate the electronic band structure of nanowhiskers based on group theory concepts and the k.p method. Although the interest is in polytypical superlattices, the proposed model was applied to a single quantum well of InP to study the physics of the wurtzite/zinc-blende polytypism. By the analysis of our results, some trends can be predicted: spatial carriers' separation, predominance of perpendicular polarization (xy plane) in the luminescence spectra, and interband transition blueshifts with strain. Also, a possible range of values for the wurtzite InP spontaneous polarization is suggested. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4767511]
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Parasitic diseases plague billions of people among the poorest, killing millions annually, and causing additional millions of disability-adjusted life years lost. Leishmaniases affect more than 12 million people, with over 350 million people at risk. There is an urgent need for efficacious and cheap vaccines and treatments against visceral leishmaniasis (VL), its most severe form. Several vaccination strategies have been proposed but to date no head-to-head comparison was undertaken to assess which is the best in a clinical model of the disease. We simultaneously assayed three vaccination strategies against VL in the hamster model, using KMPII, TRYP, LACK, and PAPLE22 vaccine candidate antigens. Four groups of hamsters were immunized using the following approaches: 1) raw extracts of baculovirus-infected Trichoplusia ni larvae expressing individually one of the four recombinant proteins (PROT); 2) naked pVAX1 plasmids carrying the four genes individually (DNA); 3) a heterologous prime-boost (HPB) strategy involving DNA followed by PROT (DNA-PROT); and 4) a Control including empty pVAX1 plasmid followed by raw extract of wild-type baculovirus-infected T. ni larvae. Hamsters were challenged with L. infantum promastigotes and maintained for 20 weeks. While PROT vaccine was not protective, DNA vaccination achieved protection in spleen. Only DNA-PROT vaccination induced significant NO production by macrophages, accompanied by a significant parasitological protection in spleen and blood. Thus, the DNA-PROT strategy elicits strong immune responses and high parasitological protection in the clinical model of VL, better than its corresponding naked DNA or protein versions. Furthermore, we show that naked DNA coupled with raw recombinant proteins produced in insect larvae biofactories -the cheapest way of producing DNA-PROT vaccines-is a practical and cost-effective way for potential "off the shelf" supplying vaccines at very low prices for the protection against leishmaniases, and possibly against other parasitic diseases affecting the poorest of the poor.
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We performed a first principles investigation on the electronic properties of 4f-rare earth substitutional impurities in zincblende gallium nitride (GaN:REGa, with RE=Eu, Gd, Tb, Dy, Ho, Er and Tm). The calculations were performed within the all electron methodology and the density functional theory. We investigated how the introduction of the on-site Hubbard U potential (GGA + U) corrects the electronic properties of those impurities. We showed that a self-consistent procedure to compute the Hubbard potential provides a reliable description on the position of the 4f-related energy levels with respect of the GaN valence band top. The results were compared to available data coming from a recent phenomenological model. (C) 2012 Elsevier B.V. All rights reserved.
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The electrical conductivity σ has been calculated for p-doped GaAs/Al0.3Ga0.7As and cubic GaN/Al0.3Ga0.7N thin superlattices (SLs). The calculations are done within a self-consistent approach to the k → ⋅ p → theory by means of a full six-band Luttinger-Kohn Hamiltonian, together with the Poisson equation in a plane wave representation, including exchange correlation effects within the local density approximation. It was also assumed that transport in the SL occurs through extended minibands states for each carrier, and the conductivity is calculated at zero temperature and in low-field ohmic limits by the quasi-chemical Boltzmann kinetic equation. It was shown that the particular minibands structure of the p-doped SLs leads to a plateau-like behavior in the conductivity as a function of the donor concentration and/or the Fermi level energy. In addition, it is shown that the Coulomb and exchange-correlation effects play an important role in these systems, since they determine the bending potential.
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[ES] Los transistores más rápidos se consiguen gracias al crecimiento de diferentes semiconductores apilados. Entre los semiconductores es posible confinar una elevada concentración de electrones de alta movilidad, dando lugar a transistores con gran velocidad de respuesta. Cuando se emplea el sistema AlGaN/GaN, los enlaces interatómicos poseen un elevado carácter iónico. Estos iones generan intensos campos eléctricos internos, que inducen entre el AlGaN y el GaN una concentración de electrones de 1013 cm-2, un orden de magnitud superior a la alcanzada con otras estructuras típicas (AlGaAs/GaAs, AlGaAs/InGaAs/GaAs, GaInP/InGaAs/GaAs, etc.). En este artículo se expone un análisis de los aspectos fundamentales relacionados con la distribución de los electrones bajo la puerta de los transistores basados en nitruros.
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Celebrado el 24 de mayo en el Edificio de Informática y Matemáticas de la ULPGC
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The running innovation processes of the microwave transistor technologies, used in the implementation of microwave circuits, have to be supported by the study and development of proper design methodologies which, depending on the applications, will fully exploit the technology potentialities. After the choice of the technology to be used in the particular application, the circuit designer has few degrees of freedom when carrying out his design; in the most cases, due to the technological constrains, all the foundries develop and provide customized processes optimized for a specific performance such as power, low-noise, linearity, broadband etc. For these reasons circuit design is always a “compromise”, an investigation for the best solution to reach a trade off between the desired performances. This approach becomes crucial in the design of microwave systems to be used in satellite applications; the tight space constraints impose to reach the best performances under proper electrical and thermal de-rated conditions, respect to the maximum ratings provided by the used technology, in order to ensure adequate levels of reliability. In particular this work is about one of the most critical components in the front-end of a satellite antenna, the High Power Amplifier (HPA). The HPA is the main power dissipation source and so the element which mostly engrave on space, weight and cost of telecommunication apparatus; it is clear from the above reasons that design strategies addressing optimization of power density, efficiency and reliability are of major concern. Many transactions and publications demonstrate different methods for the design of power amplifiers, highlighting the availability to obtain very good levels of output power, efficiency and gain. Starting from existing knowledge, the target of the research activities summarized in this dissertation was to develop a design methodology capable optimize power amplifier performances complying all the constraints imposed by the space applications, tacking into account the thermal behaviour in the same manner of the power and the efficiency. After a reminder of the existing theories about the power amplifier design, in the first section of this work, the effectiveness of the methodology based on the accurate control of the dynamic Load Line and her shaping will be described, explaining all steps in the design of two different kinds of high power amplifiers. Considering the trade-off between the main performances and reliability issues as the target of the design activity, we will demonstrate that the expected results could be obtained working on the characteristics of the Load Line at the intrinsic terminals of the selected active device. The methodology proposed in this first part is based on the assumption that designer has the availability of an accurate electrical model of the device; the variety of publications about this argument demonstrates that it is so difficult to carry out a CAD model capable to taking into account all the non-ideal phenomena which occur when the amplifier operates at such high frequency and power levels. For that, especially for the emerging technology of Gallium Nitride (GaN), in the second section a new approach for power amplifier design will be described, basing on the experimental characterization of the intrinsic Load Line by means of a low frequency high power measurements bench. Thanks to the possibility to develop my Ph.D. in an academic spin-off, MEC – Microwave Electronics for Communications, the results of this activity has been applied to important research programs requested by space agencies, with the aim support the technological transfer from universities to industrial world and to promote a science-based entrepreneurship. For these reasons the proposed design methodology will be explained basing on many experimental results.