Cosmology is an attempt to mathematically describe the behaviour of the universe, the most commonly used models are the Friedmann-Lemaître-Robertson-Walker solutions. These models seem to be accurate for an old universe, which is homogeneous with low anisotropy. However for an earlier universe these models might not be that accurate or even correct. The almost non-existent anisotropy observed today might have played a bigger role in the earlier universe. For this reason we will study another model known as Bianchi Type I, where the universe is not necessarily isotropic. We utilize a 1+3-covariant formalism to obtain the equations that determine the behaviour of the universe and then use a tetrad formalism to complement the 1+3-covariant equations. Using these equations we examine the geometry of space-time and its dynamical properties. Finally we briefly discuss the different singularities possible and examine some special cases of geodesic movement.

Made available in DSpace on 2016-06-02T20:28:22Z (GMT). No. of bitstreams: 1 DissSCC.pdf: 580893 bytes, checksum: 668c123be16c687965e925ea0bd5d17b (MD5) Previous issue date: 2004-04-15 / Universidade Federal de Minas Gerais / In this work we develop the transformation theory for isothermic surfaces in Euclidean space IR3 due to Darboux and Bianchi. As a consequence, we describe a method for constructing new solutions of the nonlinear system of partial diferential equations associated to an isothermic surface in IR3 starting from a given one. / Neste trabalho apresentamos a teoria de transformações entre superfícies isotérmicas no espaço Euclidiano IR3 devida a Darboux e Bianchi. Descrevemos, como consequência, um método de obter novas soluções do sistema não linear de equações diferenciais parciais associado a uma superfície isotérmica em IR3, a partir de uma dada.

Orientadora : Profª Drª Rosane Kaminski / Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Humanas, Programa de Pós-Graduação em História. Defesa: Curitiba, 27/06/2017 / Inclui referências : f. 147-153 / Resumo: A proposta desta pesquisa é realizar uma análise fílmica de Quanto vale ou é por Quilo? (2005), dirigido por Sérgio Bianchi, buscando fundamentar uma reflexão crítica a respeito da forma como o diretor estrutura o discurso fílmico, e como este se relaciona com seu presente. Busca-se entender como o filme se situa diante dos problemas sociais e políticos, bem como a forma pela qual o filme sugere uma leitura do passado (e das fontes históricas) com a finalidade de pautar uma interpretação crítica e irônica do presente. A narrativa aproxima a escravidão colonial ao tempo presente, apresentando de maneira crítica sua leitura a respeito da corrupção e exploração da miséria humana efetuada pelas ONGs, com o auxílio do poder público. Ao aproximar a escravidão com o contexto contemporâneo, o filme abre espaço para reflexões sobre o racismo na sociedade brasileira e, a partir disso, sobre a participação de homens e mulheres negras no cinema. A metodologia analítica tem por objetivo perceber as múltiplas escolhas e definições que dão conformação ao filme, tanto no campo estético quanto ideológico. Para isso, se faz necessária uma pesquisa contextual, que observe os problemas inerentes ao período de produção da obra, bem como uma análise estética, que nos ajude a compreender a estrutura da narrativa fílmica e suas implicações semânticas, que tem um impacto na sociedade receptora desse objeto artístico. Palavras-chave: Sérgio Bianchi. Cinema Brasileiro. Protagonismo Negro. História Contemporânea. Terceiro Setor. / Abstract: The purpose of this research is to analyze the film Quanto vale ou é por quilo? (2005), directed by Sérgio Bianchi. Therefore, the main goal here is to understand the ways in which the director structures his filmic discourse, and how it relates to his present. For this, we will interpret how the film faces some social and political problems, as well as the way in which the film suggests a reading of the past (and of historical sources) with the purpose of guiding a critical and ironic interpretation of the present. The narrative approaches colonial slavery to the present time, critically presenting its reading about the corruption and exploitation of human misery carried out by the NGOs, with the aid of the public Power. By bringing slavery closer to the contemporary context, the film suggests reflections on racism in Brazilian society and, from this, on the black men and women participation in cinema. The analytical methodology aims to perceive the multiple choices and definitions that shape the film, both in aesthetic and ideological fields. For this, it is necessary a contextual research which observes the problems from period of production of the work, as well as an aesthetic analysis that helps us to understand the structure of the filmic narrative and its semantic implications, that has an impact on the receiving society of this artistic object. Key Words: Sérgio Bianchi. Brazilian Cinema. Black protagonism. Contemporary History. Third Sector

Cette thèse étudie les modèles cosmologiques homogènes mais anisotropes en théories tenseur-scalaire. Son but est de déterminer les propriétés que doivent avoir ces théories afin que ces modèles possèdent asymptotiquement les caractéristiques dynamiques de notre Univers actuel ou apportent une réponse à certains de ses problèmes comme ceux de la constante cosmologique. La première partie de la thèse est consacrée à une introduction historique et à une justification physique des théories tenseur-scalaires de la gravitation et des modèles cosmologiques anisotropes. La seconde partie détaille les notions mathématiques nécessaires à la compréhension de cette thèse, à savoir la classification des cosmologies anisotropes et l'écriture des équations de champs dans le formalisme Lagrangien et Hamiltonien. La troisième partie est composée d'une série de sept articles montrant comment l'on peut parvenir à contraindre les théories tenseur-scalaires à l'aide de solutions exactes, en exigeant que l'Univers possède certains comportements dynamiques (expansion, inflation, etc), soit dépourvu de singularité ou possède une symétrie de Noether. Dans la quatrième partie, le processus d'isotropisation des modèles anisotropes est étudié en détail pour de nombreuses classes de théories tenseur-scalaires. Des contraintes nécessaires à l'isotropisation, les comportements asymptotiques des fonctions métriques et du potentiel au voisinage de cet état sont déterminés et le phénomène de quintessence analysé. Un lien entre les champs scalaires quintessents qui pourraient peupler notre Univers et la matière noire dans les galaxies (1 article) est montré. Les six articles à l'origine de ce chapitre sont reproduits dans la sixième partie qui tient lieu d'appendice. Nous concluons dans la cinquième partie.

<p>Einstein's theory of general relativity is a cornerstone in the process of gaining increased understanding about problems of gravitational nature. It can be applied to problems on the huge length scales of cosmology and as far as we know it does not break down before the Planck scale is approached. Irrespective of scale, a perturbative approach is often a very useful way to reduce the Einstein system to manageable complexity and size.</p><p>The projects included in this thesis can be divided into three subcategories. In the first category the keyword is photon-photon scattering. General relativity predicts that scattering can take place on a flat background due to the curvature of space-time caused by the photons themselves. The coupling equations and cross-section are found and a comparison with the corresponding quantum field theoretical results is done to leading order. Moreover, photon-photon scattering due to exchange of virtual electron-positron pairs is considered as an effective field theory in terms of the Heisenberg-Euler Lagrangian resulting in a possible setup for experimental detection of this phenomenon using microwave cavities. The second category of projects is related to cosmology. Here linear perturbations around a flat FRW universe with a cosmological constant are considered and the corresponding temperature variations of the cosmic microwave background radiation are found. Furthermore, cosmological models of Bianchi type V are investigated using a method based on the invariant scheme for classification of metrics by Karlhede. The final category is slowly rotating stars. Here the problem of matching a perfect fluid interior of Petrov type D to an exterior axisymmetric vacuum solution is treated perturbatively up to second order in the rotational parameter.</p>

<p>We derive the equation linking the Weyl tensor with its Lanczos potential, called the Weyl-Lanczos equation, in 1+3 covariant formalism for perfect fluid Bianchi type I spacetime and find an explicit expression for a Lanczos potential of the Weyl tensor in these spacetimes. To achieve this, we first need to derive the covariant decomposition of the Lanczos potential in this formalism. We also study an example by Novello and Velloso and derive their Lanczos potential in shear-free, irrotational perfect fluid spacetimes from a particular ansatz in 1+3 covariant formalism. The existence of the Lanczos potential is in some ways analogous to the vector potential in electromagnetic theory. Therefore, we also derive the electromagnetic potential equation in 1+3 covariant formalism for a general spacetime. We give a short description of the necessary tools for these calculations and the cosmological formalism we are using.</p>

Einstein's theory of general relativity is a cornerstone in the process of gaining increased understanding about problems of gravitational nature. It can be applied to problems on the huge length scales of cosmology and as far as we know it does not break down before the Planck scale is approached. Irrespective of scale, a perturbative approach is often a very useful way to reduce the Einstein system to manageable complexity and size. The projects included in this thesis can be divided into three subcategories. In the first category the keyword is photon-photon scattering. General relativity predicts that scattering can take place on a flat background due to the curvature of space-time caused by the photons themselves. The coupling equations and cross-section are found and a comparison with the corresponding quantum field theoretical results is done to leading order. Moreover, photon-photon scattering due to exchange of virtual electron-positron pairs is considered as an effective field theory in terms of the Heisenberg-Euler Lagrangian resulting in a possible setup for experimental detection of this phenomenon using microwave cavities. The second category of projects is related to cosmology. Here linear perturbations around a flat FRW universe with a cosmological constant are considered and the corresponding temperature variations of the cosmic microwave background radiation are found. Furthermore, cosmological models of Bianchi type V are investigated using a method based on the invariant scheme for classification of metrics by Karlhede. The final category is slowly rotating stars. Here the problem of matching a perfect fluid interior of Petrov type D to an exterior axisymmetric vacuum solution is treated perturbatively up to second order in the rotational parameter.

Oggigiorno diversi tipi di chiusure sono disponibili sul mercato e, tra queste, le chiusure a vite che sono molto diffuse nei paesi emergenti nel settore viti-vinicolo. L’uso dei tappi a vite, comunque, non è attualmente diffuso in relazione ai vini da invecchiamento o di alta qualità poiché a tale chiusura è associato un ambiente riducente che viene considerato poco idoneo alla conservazione di vini rossi da invecchiamento. Lo scopo di questo lavoro è stato quello di valutare, tramite analisi chimiche e sensoriali, l’evoluzione del vino tappato con diverse tipologie di chiusure a vite rispetto al sughero tradizionale e la bontà di diverse possibili condizioni di imbottigliamento. Nel corso dei tre anni di attività di dottorato sono state condotte diverse prove per testare capsule in fase di sperimentazione in confronto con chiusure a vite già impiegate in ambito enologico e con tappi sintetici e di sughero. Differenti tipologie di vino, associate a diverse tipologie di imbottigliamento e di tappi, sono state utilizzate. Alcune prove sono state condotte a termine nel breve periodo (9 mesi) mentre altre hanno richiesto tempi più lunghi. In linea generale, i risultati evidenziano, per tutti i vini, che il tempo di conservazione in bottiglia incide in maniera più significativa delle chiusure sull’evoluzione compositiva ed organolettica dei prodotti. Nel caso dei vini bianchi, il breve periodo di maturazione in bottiglia considerato non ha evidenziato differenze di composizione significative imputabili alla chiusura. Nel caso del Barbera Oltrepò Pavese i tempi lunghi di conservazione (36 mesi) hanno evidenziato che la chiusura esercita un effetto di separazione tra i vini. Quando la temperatura di stoccaggio è elevata (ad esempio 45°C) la shelf-life del prodotto si abbrevia in modo più evidente quando il prodotto è giovane. / Nowadays, there are different types of closures available on the market and, behind these, the screwcaps are very diffused in emerging enological countries. Screwcaps, however, are not used for premium or aged wines because their use is linked to a reductive environment in bottle, which is not useful for the maturation of aged red wines. The aim of this work was the evaluation, through chemical and sensorial analysis, of the evolution of wine, bottled with different types of closures and bottling conditions. During the PhD work time, different trails on experimental capsules and classical screwcaps, synthetic closures and cork closures were carried out. Several types of white and red wine, bottled in different conditions and with diverse kinds of closures, were studied. Some of the trials ended in a few months while others were longer. The results showed, for all wines, that the storage period had a significant influence on the wine evolution, more than the closure type had. The closures used for white wines in short periods of storage had no influence on the wine composition. For the Barbera Oltrepò Pavese wine, after the long storage period (36 months), the closure type exhibited a separation effect. The high storage temperature (e.g. 45°C) reduced the shelf-life of the product, particularly in case of young wines.

We derive the equation linking the Weyl tensor with its Lanczos potential, called the Weyl-Lanczos equation, in 1+3 covariant formalism for perfect fluid Bianchi type I spacetime and find an explicit expression for a Lanczos potential of the Weyl tensor in these spacetimes. To achieve this, we first need to derive the covariant decomposition of the Lanczos potential in this formalism. We also study an example by Novello and Velloso and derive their Lanczos potential in shear-free, irrotational perfect fluid spacetimes from a particular ansatz in 1+3 covariant formalism. The existence of the Lanczos potential is in some ways analogous to the vector potential in electromagnetic theory. Therefore, we also derive the electromagnetic potential equation in 1+3 covariant formalism for a general spacetime. We give a short description of the necessary tools for these calculations and the cosmological formalism we are using.

As teorias de gravitação invariante por escala propõem uma variação com relação ao tempo da constante gravitacional ou da massa dos objetos que constituem o universo. Desta forma a intensidade da interação gravitacional também se torna variável, modificando sensivelmente o comportamento do universo. Algumas teorias foram propostas no decorrer do século, porém, descartadas devido a problemas técnicos e de concordância com dados observacionais. trabalho a ser apresentado nesta dissertação está fundamentado em uma teoria de gravitação invariante por escala, a qual vem atualmente sendo desenvolvida e é denominada teoria penta-dimensional Espaço-Tempo-Massa. Tal teoria propõe a quantidade de massa de repouso como uma quantidade extensiva, de maneira a introduzi-la na métrica e torná-la variável. Diversos trabalhos foram realizados com esta teoria, incluindo alguns, o estudo de modelos cosmológicos. Investigaremos aqui a extensão do modelo cosmológico de Bianchi tipo V, que é um dos mais importantes modelos do universo. Duas métricas foram propostas e as soluções das equações de campo da teoria SD-Espaço-Tempo-Massa para tais métricas foram obtidas. Tais soluções correspondem a espaços não-planos. Um estudo sobre singularidades na métrica e na curvatura foi realizado para ambas as métricas, em adição, o tensor de energia-momento induzido foi obtido para as métricas e as suas propriedades investigadas. Através da análise do tensor de Kretschmann verificou-se a ausência de singularidades efetivas nos modelos 5D abordados, sugerindo uma distribuição finita de energia devido a inclusão da massa de repouso. / The scale invariant gravitational theories propose the time variation either in the gravitational constant or in the rest mass of the objects that constitute the universe. By this way the intensity of the gravitational interaction varies as well, changing accordingly the behavior of the universe. Several theories have been proposed in the literature, however most of them have been discharged due to drawbacks in thecnicalities or lack of agreement with observational data. The work conducted here takes into account a 5-dimensional theory called SpaceTime- Mass, which proposes that the rest mass be na extensible quantity that change with time. Severa! investigations have been done so far with this theory, some o f them including cosmological studies. Here we will investigate the 5D extension of the Bianchi type V cosmological model, which is one of the most important model of the universe. Two metrics are proposed and the solution of the corresponding 5D-Spae-Time-Mass field equations are found. Both solutions shown to be non-flat spaces. The singularity behavior of the metric and curvature were done, the induced energy-momentum tensor for both metrics were determined and their properties were investigated. Through the analysis of the Kretschmann tensor, it has been shown that there is no effective singularity in the space, which suggest that there is a finite distribution of energy due to the inclusion of the rest mass variable.