Radiação emitida por uma carga elétrica orbitando um buraco negro de Schwarzschild segundo Teoria Quântica de Campos

Desenvolvemos a quantização do campo vetorial não massivo no espaço-tempo de Schwarzschild, e calculamos a potência irradiada por uma carga elétrica em órbita circular em torno de um objeto com massa M em ambos os espaços-tempos. Em Minkowski é encontrada a expressão analítica da potência irradiada utilizando teoria quântica de campos e assumindo gravitação newtoniana. O resultado obtido é equivalente ao resultado clássico, dado que o cálculo é realizado em nível de árvore. Dadas as dificuldades matemáticas encontradas ao se tentar obter soluções expressas em termos de funções especiais conhecidas, em Schwarzschild o problema é abordado de duas formas: solução analítica no limite de baixas freqüências, e resolução numérica. O primeiro caso serviu como cheque de consistência para o método numérico. Em Schwarzschild, o cálculo também é realizado utilizando teoria quântica de campos em nível de árvore, e a expressão da potência é encontrada analiticamente na aproximação de baixas freqüências e através de métodos numérico. Após a comparação dos resultados, concluímos que, para uma mesma velocidade angular de rotação da carga (medida por observadores estatísticos assintóticos), a potência irradiada em Minkowski é maior que a potência irradiada em Schwarzschild.

Utopias pedagógicas no ensino de ciências: idéias docentes que expressam o futuro para reencantar o presente

Este estudo é concernente a uma pesquisa qualitativa na modalidade narrativa, que tem como objetivo investigar em que termos repercutem proposições teórico metodológicas e epistemológicas do presente como expressão de utopias de Educação e da Educação em Ciências. Foram ouvidas vozes dos sujeitos, coletadas sob a forma de relatos orais, por meio de entrevistas semi-estruturadas gravadas em áudio, realizadas individualmente com cada um dos sete alunos-professores participantes de um curso de educação continuada, em nível de especialização em Ensino de Ciências, no qual o pesquisador se inclui. Os sujeitos da pesquisa foram selecionados segundo a natureza ideacional de suas manifestações nas interações em aulas. Como critério de seleção dos sujeitos foi levado em conta o teor das idéias por eles geralmente manifestas em aulas, de forma tal que foram escolhidos (a) três sujeitos com idéias de inclinação utópica, (b) outros três com idéias que se aproximam do ceticismo e (c) um sujeito com traços ideacionais aproximados ao niilismo. Os dados obtidos foram tratados sob a forma de episódios narrativos, que foram organizados em função de três princípios utópicos – princípios de conhecimento, de ensino e de vida - que constituíram, cada um, uma seção de análise sob o título de: I) Aprender a conhecer para poder projetar o futuro; II) Aprender a saber-fazer: redesenhando horizontes no ensino de ciências; III) Aprender a ser: a invenção de si num mundo dinâmico. O tratamento dos episódios narrativos em termos de princípios utópicos representa um modo de organizar as questões de maior destaque para os sujeitos num contexto de inter-relações. Sendo assim, esses princípios mantêm as interconexões que constituem um processo multidimensional de resignificação permanente daquilo que, para os sujeitos, torna-se relevante manter ou projetar COMO UTOPIAS no âmbito do Ensino de Ciências. A análise dos dados revela que a perspectiva de construção de um conhecimento compreensivo no Ensino de Ciências, voltado para o desenvolvimento de uma cidadania crítica e reflexiva constitui-se uma das principais aspirações docentes, em termos de utopias pedagógicas e, para isso, torna-se necessária a superação da visão cartesiana e positivista de ensino e formação. Além disso, pressupõe, entre outros, uma articulação entre diferentes modos de ser e de fazer o ensino de ciências com base em parâmetros emergentes de compreensão da realidade, tendo em vista a construção das utopias de redes de conhecimento. Tais redes explicitam a natureza compreensiva do conhecimento, a resignificação da relação professor-aluno, a construção de um modo de conhecer que se traduza na maneira de se autoconhecer, o reconhecimento do aluno como centro da aprendizagem, as quais envolvem todos os sujeitos na dinâmica do processo educativo em termos de um processo ao longo da vida. Utopias como essas reencantam o presente na busca da construção de um futuro promissor.

O “Oriente” no “Ocidente”: observando o islã no Suriname

Esta dissertação trata do islã surinamês de origem javanesa, distante (não apenas geograficamente) do centro irradiador árabe-islâmico. O Suriname, país sul-americano e caribenho, abriga considerável comunidade muçulmana, a maior em termos percentuais fora da Ásia, África e Europa Oriental. Nele, encontra-se em curso a oposição entre o reformismo e o tradicionalismo no islã. A tendência reformista preza mais por um islã árabe puritano, universalista, com destaque para os valores morais; a tradicional prioriza a comunidade javanesa local e a tradição muçulmana oriunda de Java. A pesquisa envolveu discussões acerca da construção da identidade, da memória à qual os grupos encontram-se vinculados e das “negociações” entre o pertencimento étnico javanês e o pertencimento religioso. Um aspecto que emerge ao longo do trabalho é a diversidade do islã. No Suriname são praticadas cerimônias islâmicas semelhantes às descritas por Clifford Geertz em suas pesquisas realizadas em Java, na década de 1950, como é o caso do slametan, um rito de passagem pós-morte que expressa o momento de transição entre o mundo dos vivos e o dos mortos.

Silêncio, arte e educação transformadora

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Approximate controllability for the semilinear heat equation in RN involving gradient terms

We prove the approximate controllability of the semilinear heat equation in R^N, when the nonlinear term is globally Lipschitz and depends both on the state u and its spatial gradient Ñu. The approximate controllability is viewed as the limit of a sequence of optimal control problems. In order to avoid the difficulties related to the lack of compactness of the Sobolev embeddings, we work with the similarity variables and use weighted Sobolev spaces.

Comportamento fractal de superfície da zona de estiramento em aço 300M temperado

Fracture surfaces are the fracture process marks, taht it is characterized by energy release guieded by failure mode. The fracture toughness express this energy em stress and strain terms in pre-cracked samples. The strectch zone is the characteristic region forms by the transition of fatigue fracture and final fracture and it width demonstrate the relation with failure energy release.The quantitative fractography is a broadly tool uses in failure surfaces characterization that it can point to a material’s aspect or a fracture process. The image processing works like an investigation tool, guinding a lot of studies in this area. In order to evaluate the characterization effectivity and it respectivity studies, it used 300M steel that it was thermal treated by an aeronautical process known and it characterized by tensile test and energy dispersive spectroscopy (EDS). The tensile test of this material, made by ASTM E8, allowed the head treatment effectivity confirmation, beyond of mechanics porperties determination. The EDS confirmed the material composition, beyond of base the discussion about fracture mechanism presence. The fracture toughness test has also made, that it works to obtain the fracture surfeaces studies below self-similarity and self-affinity approaches. In front of all the exposed it was possible to conclude that the fractal dimension works like a study parameter of fracture process, allowinf the relation of their values with changes in thickness, which interferes directly in material’s behaviour in fracture toughness approach

Tailoring the refractive index of Ge-S based glass for 3D embedded waveguides operating in the mid-IR region

The photosensitivity of GeSx binary glasses in response to irradiation to femtosecond pulses at 800 nm is investigated. Samples with three different molecular compositions were irradiated under different exposure conditions. The material response to laser exposure was characterized by both refractometry and micro-Raman spectroscopy. It is shown that the relative content of sulfur in the glass matrix influences the photo-induced refractive index modification. At low sulfur content, both positive and negative index changes can be obtained while at high sulfur content, only a positive index change can be reached. These changes were correlated with variations in the Raman response of exposed glass which were interpreted in terms of structural modifications of the glass network. Under optimized exposure conditions, waveguides with positive index changes of up to 7.8x10−3 and a controllable diameter from 14 to 25 μm can be obtained. Direct inscription of low insertion losses (IL = 3.1 – 3.9 dB) waveguides is demonstrated in a sample characterized by a S/Ge ratio of 4. The current results open a pathway towards the use of Ge-S binary glasses for the fabrication of integrated mid-infrared photonic components.

Power quality, smart meters and additional information from different power terms

This paper shows how the detailed examination of active and nonactive power components may produce new information for modern smart meters. For this purpose, a prototype of electronic power meter has been implemented and applied to the evaluation of the Conservative Power Theory (CPT). Considering five sorts of loads, under four different operating conditions, the experimental results indicate that the CPT is able to provide a good methodology for load characterization, which could possibly benefits consumers and power utilities in several different ways. The results also show that depending on the situation, the analysis of nonactive power terms may be more important than the observation of traditional power quality indices, such as total harmonic distortion, unbalance factors or the fundamental positive sequence power factor.

Semi-supervised learning for relevance feedback on image retrieval tasks

Relevance feedback approaches have been established as an important tool for interactive search, enabling users to express their needs. However, in view of the growth of multimedia collections available, the user efforts required by these methods tend to increase as well, demanding approaches for reducing the need of user interactions. In this context, this paper proposes a semi-supervised learning algorithm for relevance feedback to be used in image retrieval tasks. The proposed semi-supervised algorithm aims at using both supervised and unsupervised approaches simultaneously. While a supervised step is performed using the information collected from the user feedback, an unsupervised step exploits the intrinsic dataset structure, which is represented in terms of ranked lists of images. Several experiments were conducted for different image retrieval tasks involving shape, color, and texture descriptors and different datasets. The proposed approach was also evaluated on multimodal retrieval tasks, considering visual and textual descriptors. Experimental results demonstrate the effectiveness of the proposed approach.

Construction of R4 terms in N = 2 D = 8 superspace

Using linearized superfields, R4 terms in the Type II superstring effective action compactified on T2 are constructed as integrals in N = 2 D = 8 superspace. The structure of these superspace integrals allows a simple proof of the R4 non-renormalization theorems which were first conjectured by Green and Gutperle. © 1998 Elsevier Science B.V.

Efficiency in Brazil's industrial sectors in terms of energy and sustainable development

This article evaluates the efficiency of Brazil's industrial sectors from 1996 to 2009, taking into account energy consumption and respective contributions to the country's economic and social aspects. This analysis used a mathematical programming method called Data Envelopment Analysis (DEA), which enabled, from the SBM model and the window analysis, to evaluate the ability of industries to reduce energy consumption and fossil-fuel CO2 emissions (inputs), as well as to increase the Gross Domestic Product (GDP) by sectors, the persons employed and personnel expenses (outputs). The results of this study indicated that the Textile sector is the most efficient industrial sector in Brazil, according to the variables used, followed by these sectors: Foods and Beverages, Chemical, Mining, Paper and Pulp, Nonmetallic and Metallurgical.

Examining the use of terms "Conservation" "Restoration" and "Preservation" between Natural Resource Professionals and Literature Reviews

ABSTRACT This thesis will determine if there is a discrepancy between how literature defines conservation, preservation, and restoration, and how natural resource professionals define these terms. Interviews were conducted with six professionals from six different agencies that deal with natural resources. These agencies consisted of both government and non-government groups. In addition to interviewing these professionals regarding how they define the terms, they were asked where their work fits into the context of these terms. The interviewees’ responses were then compared with the literature to determine inconsistencies with the use of these terms in the literature and real world settings. The literature and the interviewees have agreed on the term conservation. There are some different points of view about preservation, some see it as ‘no management’ and some others see it as keeping things the same or ‘static.’ Restoration was the term where both the literature and professionals thought of moving an ecosystem from one point of succession or community, to another point on a continuum. The only thing in which they disagree on is the final goal of a restoration project. The literature would suggest restoring the ecosystem to a past historic condition, where the interviewees said to restore it to the best of their abilities and to a functioning ecosystem.

The in vitro antioxidant properties of the Al-quercetin/beta CD and Al-catechin/beta CD inclusion compounds, rationalized in terms of their electrochemical behaviour

Inclusion compounds of Al-quercetin and Al-catechin complexes with beta-cyclodextrin (beta CD) were investigated. The complex and the inclusion compound of quercetin are more effective DPPHaEuro cent scavengers than the corresponding catechin compounds and the inclusion does not compromise their scavenging abilities, with only a slight decrease in the EC50 values. This is in accordance with the electrochemical data, which revealed that the inclusion compounds have lower diffusion coefficients in aqueous solution than the non-included compounds. For the quercetin compounds, some spectroscopic properties were also addressed by means of UV-visible and NMR measurements in aqueous media.

Human Adipose-Derived Mesenchymal Stromal Cells Injected Systemically Into GRMD Dogs Without Immunosuppression Are Able to Reach the Host Muscle and Express Human Dystrophin

Duchenne muscular dystrophy (DMD), a lethal X-linked disorder, is the most common and severe form of muscular dystrophies, affecting I in 3,500 male births. Mutations in the DMD gene lead to the absence of muscle dystrophin and a progressive degeneration of skeletal muscle. The possibility to treat DMD through cell therapy has been widely investigated. We have previously shown that human adipose-derived stromal cells (hASCs) injected systemically in SJL mice are able to reach and engraft in the host muscle, express human muscle proteins, and ameliorate the functional performance of injected animals without any immunosuppression. However, before starting clinical trials in humans many questions still need to be addressed in preclinical studies, in particular in larger animal models, when available. The best animal model to address these questions is the golden retriever muscular dystrophy (GRMD) dog that reproduces the full spectrum of human DMD. Affected animals carry a mutation that predicts a premature termination codon in exon 8 and a peptide that is 5% the size of normal dystrophin. These dogs present clinical signs within the first weeks and most of them do not survive beyond age two. Here we show the results of local and intravenous injections of hASCs into GRMD dogs, without immunosuppression. We observed that hASCs injected systemically into the dog cephalic vein are able to reach, engraft, and express human dystrophin in the host GRMD dystrophic muscle up to 6 months after transplantation. Most importantly, we demonstrated that injecting a huge quantity of human mesenchymal cells in a large-animal model, without immunosuppression, is a safe procedure, which may have important applications for future therapy in patients with different forms of muscular dystrophies.