499 research outputs found

    O Projeto Rondon e os impactos na vida dos acadêmicos da PUCPR

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    Trabalho apresentado no II Congresso Nacional do PROJETO RONDON, realizado em Florianópolis, SC, no período de 23 a 25 de setembro de 2015 - Universidade Federal de Santa Catarina.O Brasil possui 202.033.670 habitantes distribuídos em 8.515.767,049 km² (IBGE, 2014). Esses são 2 indicadores utilizados amplamente para se definir o contexto físico do país. Porém é necessário ir além, pois nesse território tão grande e diversificado encontram-se muitas etnias, culturas e povos. É preciso aprender a história do Brasil, mas também percorrê-lo, conhecer de perto a sua realidade. Em função disso, o Projeto Rondon foi criado, e durante as décadas de 1970 e 1980 permaneceu em plena atividade, levando desenvolvimento para as regiões mais afastadas do país, além de permitir aos acadêmicos de todo o Brasil a visão real de sua nação. Em 1989 o programa foi extinto, voltando somente 15 anos depois e com uma nova forma, a qual a Pontifícia Universidade Católica do Paraná (PUCPR) participa enviando projetos desde 2011. Em razão desses 5 anos de atuação é que o objetivo do trabalho se encontra, avaliando de que forma a ação dos acadêmicos têm se dado e os impactos que foram observados após o retorno. De acordo com o histórico das operações têm-se informações referentes ao ano de atuação, conjunto e curso do acadêmico, onde se pode analisar através de gráficos e tabelas como se deu a atuação da universidade e o perfil do acadêmico que procura o Projeto Rondon na instituição. Primeiramente, pode-se constatar que durante os 5 anos a PUCPR participou de 11 operações, nos conjuntos A e B. A universidade tem um núcleo que é responsável por selecionar os acadêmicos interessados em fazer parte do Projeto Rondon, pois há uma procura muito significativa. Na seleção avalia-se o aluno de acordo com o perfil descrito no guia do rondonista. A PUCPR adota a metodologia onde quem elabora integralmente o projeto são os acadêmicos selecionados, o qual exige muito estudo e pesquisa, procurando mostrar ao aluno que é possível colocar seus conhecimentos em prol da cidadania, despertando profissionais protagonistas e lideranças comprometidas. Procurou-se analisar como foi e esta sendo a atuação dos acadêmicos após a experiência e foi instigante perceber o espírito de cidadania preconizado pelo projeto, pois é possível evidenciar o envolvimento em outras iniciativas sociais, ONG’s e até mesmo como isso implica no projeto de vida e suas escolhas profissionais

    Hawking Radiation as Tunneling: the D-dimensional rotating case

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    The tunneling method for the Hawking radiation is revisited and applied to the DD dimensional rotating case. Emphasis is given to covariance of results. Certain ambiguities afflicting the procedure are resolved.Comment: Talk delivered at the Seventh International Workshop Quantum Field Theory under the influence of External Conditions, QFEXT'05, september 05,Barcelona, Spain. To appear in Journal of Phys.

    Oxygen Consumption in South African Sauvignon Blanc Wines: Role of Glutathione, Sulphur Dioxide and Certain Phenolics

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    The aim of this research was to investigate the interaction between sulphur dioxide, glutathione (GSH) andcertain phenols in the presence of oxygen in a synthetic wine and in clarified Sauvignon blanc wine. In thisstudy, the clarified wine, from which most of the phenols had been removed, was compared to syntheticwine solution, with both mediums being enriched with caffeic acid to investigate the effect of different levelsof sulphur dioxide and GSH on oxygen consumption. Moreover, thirteen young South African Sauvignonblanc wines with different levels of sulphur dioxide were oxygenated, and the oxygen consumption andphenolic and colour changes were monitored over time. The results show that oxygen consumption wasinfluenced greatly by the presence of sulphur dioxide and, to a lesser extent, by the presence of GSH,with both compounds decreasing during the course of the experiment. During oxidation, an increasewas observed in glutathionyl caffeic acid, as well as in oxidised glutathione (GSSG); however, this didnot coincide with the percentage decrease in GSH. Oxidation further led to an increase in absorbancemeasurements at 420 and 440 nm (yellow-orange colour), which were reduced by the presence of SO2. Alarge variation was also observed in the oxygen consumption of the young wines, with this rate increasingwith an increase in SO2 concentration. Positive correlations were also observed between oxygen, SO2, GSHand Cu concentrations, which were again negatively correlated with absorbance at 420 and 440 nm andGSSG concentrations

    Hawking Radiation as Tunneling for Extremal and Rotating Black Holes

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    The issue concerning semi-classical methods recently developed in deriving the conditions for Hawking radiation as tunneling, is revisited and applied also to rotating black hole solutions as well as to the extremal cases. It is noticed how the tunneling method fixes the temperature of extremal black hole to be zero, unlike the Euclidean regularity method that allows an arbitrary compactification period. A comparison with other approaches is presented.Comment: 17 pages, Latex document, typos corrected, four more references, improved discussion in section

    Oxygen Consumption in South African Sauvignon Blanc Wines: Role of Glutathione, Sulphur Dioxide and Certain Phenolics

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    The aim of this research was to investigate the interaction between sulphur dioxide, glutathione (GSH) and certain phenols in the presence of oxygen in a synthetic wine and in clarified Sauvignon blanc wine. In this study, the clarified wine, from which most of the phenols had been removed, was compared to synthetic wine solution, with both mediums being enriched with caffeic acid to investigate the effect of different levels of sulphur dioxide and GSH on oxygen consumption. Moreover, thirteen young South African Sauvignon blanc wines with different levels of sulphur dioxide were oxygenated, and the oxygen consumption and phenolic and colour changes were monitored over time. The results show that oxygen consumption was influenced greatly by the presence of sulphur dioxide and, to a lesser extent, by the presence of GSH, with both compounds decreasing during the course of the experiment. During oxidation, an increase was observed in glutathionyl caffeic acid, as well as in oxidised glutathione (GSSG); however, this did not coincide with the percentage decrease in GSH. Oxidation further led to an increase in absorbance measurements at 420 and 440 nm (yellow-orange colour), which were reduced by the presence of SO2. A large variation was also observed in the oxygen consumption of the young wines, with this rate increasing with an increase in SO2 concentration. Positive correlations were also observed between oxygen, SO2, GSH and Cu concentrations, which were again negatively correlated with absorbance at 420 and 440 nm and GSSG concentrations

    Obesity, body fat distribution and eye diseases.

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    Background: The prevalence of obesity, a chronic disease, is increasing, and obesity is now considered a global epidemic. Eye diseases are also increasing worldwide and have serious repercussions on quality of life as well as increasingly high costs for the community. The relationships between obesity and ocular pathologies are not yet well clarified and are not pathologically homogeneous: they seem to be somehow linked to excess body fat, especially to the distribution of adipose tissue and its ectopic deposits. Purpose: Our objective was to examine the associations between obesity and anthropometric indices, including body mass index (BMI), waist circumference (WC), and the waist/hip ratio (WHR), and the risk of most widespread eye diseases, with particular attention given to the most significant metabolic mechanisms. Methods: This article provides a narrative overview of the effect of obesity and anthropometric measurements of body fat on prevalent eye diseases. We used the MEDLINE/PubMed, CINAHL, EMBASE, and Cochrane Library databases from 1984 to 2024. In addition, we hand-searched references from the retrieved articles and explored a number of related websites. A total of 153 publications were considered. Results: There is significant evidence that obesity is associated with several eye diseases. Waist circumference (WC) and the waist/hip ratio (WHR) have been observed to have stronger positive associations with eye diseases than BMI. Conclusions: Obesity must be considered a significant risk factor for eye diseases; hence, a multidisciplinary and multidimensional approach to treating obesity, which also affects ocular health, is important. In the prevention and treatment of eye diseases related to obesity, lifestyle factors, especially diet and physical activity, as well as weight changes, both weight loss and weight gain, should not be overlooked

    Tunnelling Methods and Hawking's radiation: achievements and prospects

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    The aim of this work is to review the tunnelling method as an alternative description of the quantum radiation from black holes and cosmological horizons. The method is first formulated and discussed for the case of stationary black holes, then a foundation is provided in terms of analytic continuation throughout complex space-time. The two principal implementations of the tunnelling approach, which are the null geodesic method and the Hamilton-Jacobi method, are shown to be equivalent in the stationary case. The Hamilton-Jacobi method is then extended to cover spherically symmetric dynamical black holes, cosmological horizons and naked singularities. Prospects and achievements are discussed in the conclusions.Comment: Topical Review commissioned and accepted for publication by "Classical and Quantum Gravity". 101 pages; 6 figure

    Instability of generalised AdS black holes and thermal field theory

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    We study black holes in AdS-like spacetimes, with the horizon given by an arbitrary positive curvature Einstein metric. A criterion for classical instability of such black holes is found in the large and small black hole limits. Examples of large unstable black holes have a B\"ohm metric as the horizon. These, classically unstable, large black holes are locally thermodynamically stable. The gravitational instability has a dual description, for example by using the AdS7×S4AdS_7 \times S^4 version of the AdS/CFT correspondence. The instability corresponds to a critical temperature of the dual thermal field theory defined on a curved background.Comment: 1+16 pages. 1 figure. LaTeX. Minor clarification

    Topological dilaton black holes

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    In four-dimensional spacetime, when the two-sphere of black hole event horizons is replaced by a two-dimensional hypersurface with zero or negative constant curvature, the black hole is referred to as a topological black hole. In this paper we present some exact topological black hole solutions in the Einstein-Maxwell-dilaton theory with a Liouville-type dilaton potential.Comment: 8 pages, Revtex, no figure

    Generalized Painleve-Gullstrand descriptions of Kerr-Newman black holes

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    Generalized Painleve-Gullstrand metrics are explicitly constructed for the Kerr-Newman family of charged rotating black holes. These descriptions are free of all coordinate singularities; moreover, unlike the Doran and other proposed metrics, an extra tunable function is introduced to ensure all variables in the metrics remain real for all values of the mass M, charge Q, angular momentum aM, and cosmological constant \Lambda > - 3/(a^2). To describe fermions in Kerr-Newman spacetimes, the stronger requirement of non-singular vierbein one-forms at the horizon(s) is imposed and coordinate singularities are eliminated by local Lorentz boosts. Other known vierbein fields of Kerr-Newman black holes are analysed and discussed; and it is revealed that some of these descriptions are actually not related by physical Lorentz transformations to the original Kerr-Newman expression in Boyer-Lindquist coordinates - which is the reason complex components appear (for certain ranges of the radial coordinate) in these metrics. As an application of our constructions the correct effective Hawking temperature for Kerr black holes is derived with the method of Parikh and Wilczek.Comment: 5 pages; extended to include application to derivation of Hawking radiation for Kerr black holes with Parikh-Wilczek metho
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