Orientador: Alberto Vazquez Saa / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-22T06:52:24Z (GMT). No. of bitstreams: 1 Freitas_VanessaPachecode_M.pdf: 1200814 bytes, checksum: 8b3bfadc5901d2f7c992d013c3957d07 (MD5) Previous issue date: 2013 / Resumo: Podemos utilizar o conhecido m'etodo "Deslocar, cortar e refletir¿ para construir soluc¿oes exatas das Equac¿oes de Einstein correspondentes 'a espacos-tempo com distribuic¿oes discoidais de materia. Esse metodo consiste na introduc¿ao de uma descontinuidade na primeira derivada do tensor metrico. O resultado é uma soluc¿ao com uma singularidade do tipo delta de Dirac na hipersuperficie z = 0. Nosso estudo se restringiu a discos finos estaticos utilizando as soluc¿oes de Schwarzschild e Gutsunaev-Manko, sendo esta a representac¿ao de um objeto massivo com configurac¿ao de campo magnetico com simetria dipolar. Incluiu-se tambem o estudo da estabilidade da orbita de particulas-teste no disco, generalizando os criterios de estabilidade de Rayleigh e uma segunda analise para testar a estabilidade do disco atraves de uma perturbac¿ao no tensor energia-momento. / Abstract: We can use the well-known "Displace, cut and reflect¿ method to construct exact solutions of Einstein Equations that correspond to space-times with disklike distribution of matter. This method consists on the introduction of a discontinuity in the first-order derivative of the metric tensor. The result is a solution with a singularity of the Dirac delta type in the hypersurface Z = 0. Our study was restricted to static thin disks using Schwarzschild and Gutsunaev-Manko solutions, being the last the representation of a massive object with magnetic field configuration with dipolar symmetry. We include also the stability study of test-particles orbits at the disk, generalizing the Rayleigh criteria of stability and a second analysis to test the stability of the disk through a perturbation in the energy-momentum tensor / Mestrado / Física / Mestra em Física

Submitted by Haroudo Xavier Filho (haroudo.xavierfo@ufpe.br) on 2016-04-08T18:59:56Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_PatriciaTenório_BC.pdf: 884166 bytes, checksum: 0a78095c224981af6d91420fd610f878 (MD5) / Made available in DSpace on 2016-04-08T18:59:56Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_PatriciaTenório_BC.pdf: 884166 bytes, checksum: 0a78095c224981af6d91420fd610f878 (MD5) Previous issue date: 2015-09-17 / Dissertação resultado da pesquisa de Mestrado em Letras, área de concentração Teoria da Literatura, linha de pesquisa Intersemiose, no Programa de Pós-Graduação em Letras da Universidade Federal de Pernambuco, tendo como objetivo relacionar o romance O retrato de Dorian Gray, de Oscar Wilde, com três pilares teóricos: o índice fotográfico de Charles Sanders Peirce, o tempo de Agostinho de Hipona e a prefiguração no conceito de figura de Erich Auerbach. A cada capítulo, outros teóricos são convidados a dialogar, tais como John R. Searle, Susan Sontag, Philippe Dubois, Roland Barthes, Albert Einstein, Henri Bergson, Georges Didi-Huberman e Gaston Bachelard. / Dissertation result of Master’s research in Literature, area of concentration Literary Theory, line of research Intersemiosis, in the Postgraduate Program in Literature from the Federal University of Pernambuco, having as objective order to relate the novel The Picture of Dorian Gray, by Oscar Wilde, with three theoretical pillars: the photographic index of Charles Sanders Peirce, the time of Augustine from Hippona and the foreshadowing in the concept of figure from Erich Auerbach. Each chapter, other theorists are invited to dialogue, such as John R. Searle, Susan Sontag, Philippe Dubois, Roland Barthes, Albert Einstein, Henri Bergson, Georges Didi-Huberman and Gaston Bachelard.

Orientadores: Alberto Vazquez Saa, Marcus Aloizio Martinez de Aguiar / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-27T13:28:54Z (GMT). No. of bitstreams: 1 Vieira_RonaldoSavioliSume_D.pdf: 9121576 bytes, checksum: eab8bcedfd86d048afd51f4b65fe9501 (MD5) Previous issue date: 2015 / Resumo: Neste trabalho analisamos aspectos dinâmicos de sistemas astrofísicos que possuem uma componente discoidal proeminente. Estudamos o movimento de partículas de teste (estrelas) que cruzam discos galácticos bidimensionais e axialmente simétricos, obtendo uma fórmula para o envelope das órbitas que depende somente da densidade superficial $\Sigma$ do disco. Essa fórmula nos dá uma terceira integral de movimento aproximada para o sistema. Também analisamos a estabilidade das órbitas circulares equatoriais nesses discos, chegando à condição de estabilidade vertical $\Sigma>0$. Esse formalismo é estendido para discos tridimensionais, assim como para a relatividade geral (em que obtivemos que a \textit{condição de energia forte} é suficiente para a estabilidade vertical das órbitas circulares em discos infinitesimais, no caso estático e axialmente simétrico). Trabalhamos também com a aproximação pós-newtoniana (1PN), obtendo o formalismo hamiltoniano para uma distribuição arbitrária de matéria, assim como as correções 1PN nas frequências epicíclicas radial e vertical para configurações estacionárias e axialmente simétricas e a terceira integral de movimento aproximada para discos infinitesimais (estacionários). Outro resultado obtido foi a dependência das frequências epicíclicas com a curvatura riemanniana do espaço-tempo para distribuições suaves de matéria-energia, no caso estático e axialmente simétrico em relatividade geral. A segunda parte desta tese corresponde aos resultados para discos de acreção. Analisamos o movimento de partículas de teste na métrica de Kehagias & Sfetsos (solução esfericamente simétrica da gravitação de Horava no caso em que o espaço-tempo é assintoticamente plano), na região de parâmetros em que a singularidade central é nua. Por fim, estudamos a espessura dos discos de acreção super-Eddington obtida por simulações globais recentes de radiation magnetohydrodynamics em relatividade geral. O resultado foi comparado com modelos de discos slim para taxas de acreção similares, levando à conclusão de que o estado final (estacionário) dos fluxos de acreção gerados por essas simulações é um disco slim, e não um disco espesso, como seria esperado pelas características das configurações iniciais do tipo Polish Doughnuts usualmente adotadas / Abstract: In this work, we analyze dynamical aspects of astrophysical systems containing a prominent discoidal component. We study the motion of test particles (stars) which cross bidimensional, axially symmetric galactic disks, obtaining a formula for the orbits' envelope which depends solely on the disk's surface density. This formula gives us an approximate third integral of motion for the system. We also analyze the stability of equatorial circular orbits in these disks, arriving at the vertical stability condition $\Sigma>0$. This formalism is extended to three-dimensional disks, as well as to general relativity (in which we obtained that the \textit{strong energy condition} is sufficient for vertical stability of circular orbits in infinitesimal disks, in the static and axially symmetric case). We also worked with the post-Newtonian approximation (1PN), obtaining the Hamiltonian formalism for an arbitrary matter distribution, as well as the 1PN corrections to the radial and vertical epicyclic frequencies for stationary and axially symmetric configurations, and the approximated third integral of motion for (stationary) infinitesimal disks. Another result obtained was the dependence of the epicyclic frequencies on the Riemannian spacetime curvature for smooth matter-energy distributions, in the static and axially symmetric case. The second part of this thesis corresponds to the results concerning accretion disks. We analyzed the motion of test particles in the Kehagias & Sfetsos metric (spherically symmetric solution to Horava's gravity in the case in which the spacetime is asymptotically flat), in the parameter region in which the singularity is naked. Finally, we studied the thickness of super-Eddington accretion disks, obtained via recent global radiation magnetohydrodynamics simulations in general relativity. The result was compared with slim-disk models for similar accretion rates, leading to the conclusion that the final (stationary) state of accretion flows generated by these simulations is a slim disk, and not a thick disk, as it would be expected by the characteristics of the usually adopted Polish Doughnuts initial configurations / Doutorado / Física / Doutor em Ciências

Neste trabalho estudamos a dinâmica de discos torcidos finos e espessos para compreender melhor a propagação da deformação nestes discos. No caso dos discos finos, estudamos a física do efeito Bardeen-Petterson e aplicamos este modelo para explicar o jato em escalas de parsec e kilo-parsec da galáxia NGC 1275. Encotramos que o efeito Bardeen-Petterson reproduziu muito bem a forma do jato e com isto derivamos os parâmetros do disco como raio, valores das viscosidades azimutal e vertical, lei de potência da densidade superficial e spin do buraco negro. Para uma melhor compreensão da física destes discos, realizamos simulações GRMHD de discos moderadamente finos tanto planos como inclinados para estudar a evolução do ângulo de inclinação entre os momentos angular do buraco negro e do disco de acresção assim como o ângulo de torção que está associado com a precessão do disco. Encontramos que quando o disco de acresção e o buraco negro rotacionam no mesmo sentido, o ângulo de inclinação entre os momentos angular apresentou um comportamento oscilatório na parte interna do disco e permaneceu constante na parte externa em acordo com as previsões teóricas. Já quando o buraco negro rotacina no sentido oposto ao disco de acresção, encontramos pela primeira vez numa simulação GRMHD evidências de alinhamento, ocorrendo um alinhamento de 10\\% do angulo entre os momentos angulares do disco e buraco negro. Além disso, comprovamos pela primeira vez numa simulação GRMHD a não isotropia do stress. Utilizando um modelo semi-analítico, comparamos os resultados de nossas simulações com este modelo, utilizando os dados da simulações de disco plano como entrada e obitivemos os mesmos comportamentos das simulações tanto no caso prógrado quanto no caso retrógrado mostrando que o alinhamento é devido ao regime onda. / In this work we studied the dynamics of twisted thin and thick disks to better understand how the warp propagates in these discs. In the case of thin discs, we studied the physics of the Bardeen-Petterson effect and we applied this model to explain the shape of the jet in both parsec and kilo-parsec scales of the galaxy NGC 1275. We found that the Bardeen-Petterson effect could explain very well the shape of the jet and with that we derived the disc parameters such as its radius, the values of the kinematic azimutal and vertical viscosities, the power-law of the surface density and the spin of the black hole. To better understand the physics of such discs, we have performed GRMHD simulations of moderatelly thin tilted disks to study the evolution of the tilt angle between the angular momentum of the accretion disk and black hole and also the twist angle which is associated with the precession of the disc. We found that when the accretion disc and the black hole are rotating in the same direction, the tilt angle showed an oscillatory behavior in the inner parts of the disk while in the outer parts it remained constant in agreement with the theorical modelos. However, when both rotate in the opposite direction, we found for the very first time in a GRMHD simulation, evidences of alignment of 10\\% of the tilt angle. Besides that, we prove for the first time in a GRMHD simulation that the stress is far from being isotropic. Using a semi-analitic model, we compared the results of our simulations with this model, using the datas of the untilted simulations as inputs and we found the same behaviors found in the simulations even in prograde case as in the retrograde case showing that the alignment is due to bending waves.

Dans cette thèse nous étudions le problème de Cauchy en relativité générale. Motivés par la conjecture de censure cosmique faible formulée par Penrose, nous analysons le problème aux données initiales pour les équations d'Einstein dans le vide en faible régularité. Nous démontrons les deux résultats suivants. o Premièrement, nous nous intéressons aux équations de contrainte pour les données initiales et mettons en place une procédure de prolongement. Plus précisément, étant donné des données initiales pour les équations d'Einstein sur la boule unité dans R3, nous les prolongeons de manière continue en des données globales, asymptotiquement plates sur R3. Les équations de contrainte forment un système couplé d'équations non-lineaires sous-determinées géométriques. La preuve de notre procédure de prolongement repose sur un schéma iteratif où nous séparons ce système en deux problèmes de prolongement decouplés et solubles. Enfin, le résultat de prolongement pour les équations de contrainte est obtenu par un argument de point fixe. o Deuxièment, nous prouvons une version localisée du théorème de courbure L2 de Klainerman-Rodnianski-Szeftel. Nous montrons que, étant données des données initiales pour les équations d'Einstein sur une variété compacte avec bord, le temps d'existence de la solution des équations d'Einstein dans le domaine de dépendance de ces données initiales ne dépend que de normes de basse régularité des données initiales. En particulier, notre résultat est un critère localisé de continuité pour les équations d'Einstein. Notre preuve utilise un argument de localisation où, tout d'abord, nous généralisons la théorie de Cheeger-Gromov de convergence pour les variétés Riemanniennes à notre cas de régularité faible, et ensuite nous appliquons la procédure de prolongement pour les équations de contrainte mentionnée ci-dessus avec un argument de changement d’échelle. / In this thesis we study the Cauchy problem of general relativity. Motivated by the weak cosmic censorship conjecture formulated by Penrose, we analyse the initial value problem for the Einstein vacuum equations in low regularity. We prove the following two results. First, we consider the constraint equations of the initial data and demonstrate an extension procedure. More precisely, given small initial data for the Einstein equations on the unit ball in R3, we continuosly extend it to global, asymptotically flat initial data on R3. The constraint equations for the Einstein vacuum equations are a coupled system of non-linear under-determined geometric elliptic equations. The proof of our extension procedure is based on an iterative scheme where we split this system into two decoupled, solvable extension problems. The extension result for the constraint equations follows then by a fix point argument. Second, we prove a localised version of the bounded L2-curvature theorem by Klainerman-Rodnianski-Szeftel. We show that given low regularity initial data to the Einstein equations on a compact manifold with boundary, the time of existence of the solution to the Einstein equations in the domain of dependence of the initial data depends only on low regularity geometric data. In particular, this result is a localised continuation criterion for the Einstein vacuum equations. Our proof uses a localisation argument where we first generalise the known Cheeger-Gromov convergence theory for Riemannian manifolds to our low regularity setting, and then apply the above extension procedure for the constraint equations with a scaling argument.

Le but à long terme de mon travail de recherche est de trouver une alternative viable à la méthode conforme, qui nous permettrait de mieux comprendre la structure géométrique de l'espace des solutions des équations de contrainte. L'avantage du modèle de Maxwell (the drift model) par rapport aux modèles plus classiques est la présence des paramètres supplémentaires. Le prix à payer, par contre, sera que la complexité analytique du système correspondant. Ma thèse a été structuré en deux parties : a. Existence sous la condition de petitesse des données initiales. Nous avons montré que le système de Maxwell est raisonnable dans le sens où nous pouvons le résoudre, malgré sa forte nonliniarité, sous des conditions de petitesse sur ses coefficients, en dimension 3, 4 et 5. Par conséquent, l'ensemble des solutions est non-vide. b. Stabilité Nous montrons la stabilité des solutions du système: ce résultat est obtenu en dimension 3,4 et 5, dans le cas où la métrique est conformément plate, et le drift et petit / The long-term goal of my work is to find a viable alternative to the conformal method, which would allow us to better understand the geometry of the space of solutions of the constraint equations. The advantage of Maxwell's model (the drift model) is the presence of additional parameters. Its downside, however, is that it proves to be much more difficult from an analytic standpoint. My thesis is structued in two parts: a. Existence under suitable smallness conditions. We show that Maxwell's system is sufficiently reasonable: it can be solved even given the presence of focusing non linearities. We prove this under smallness conditions of its coefficients, and in dimensions 3,4 and 5. An immediate consequence is that the set of solutions is non-empty. b. Stability. We verify that the solutions of the system are stable: this result holds in dimensions 3,4 and 5, when the metric is conformally flat and the drift is small

The last decades have witnessed the resurgence of research on linguistic relativity, which provides empirical evidence of possible language effects on thought across various perceptual domains. This study investigated the linguistic relativity hypothesis in the abstract domain of time by looking at how L1 Chinese - L2 English bilinguals conceptualize time in two-dimensional space. English primarily relies on horizontal spatial items to talk about time (e.g., back to youth); in addition to horizontal spatial metaphors (e.g., ‘front year’), Chinese speakers also commonly use vertical metaphors to describe time (e.g., ‘up week’). If language has an effect on thought, then spatial-temporal metaphors should shape people’s temporal cognition. In this study, we examined whether spatial-temporal metaphors impact online processing of time and long-term habitual thinking about time. Experiment 1 showed that bilinguals could automatically access the timeline which corresponded to the immediate linguistic context. In Experiment 2, a majority of bilinguals demonstrated salient vertical bias for temporal reasoning, whereas a small number of participants relied on the horizontal axis to represent time. The dominant thinking patterns for time documented here (65% prefer a vertical representation of time; 35% horizontal) run counter to the fact that horizontal metaphors are twice as common in Chinese as vertical metaphors. Further, it was found that bilinguals who used English more frequently were more likely to have a less vertical bias, which suggested a role of L2 experience in conceptual representations. Taken together, the evidence in this study showed that spatial-temporal metaphors have both short-term and long-term effects on mental representations of time, but also that space-time mappings do not depend solely on linguistic factors.

We are interested in complex electronic structures of various atomic and ionics systems. We use an ab initioapproach, the multiconfigurational Dirac-Hartree-Fock (MCDHF), to compute atomic structures and properties.We contribute in three main ways to the already existent literature: by developing and implementing originalcomputer programs, by investigating possibilities of alternative computational methodologies and strategies, andfinally by performing accurate atomic structure calculations to support other research fields, i.e. nuclear physics,astrophysics or experimental physics, through the theoretical estimation of relevant atomic data.We raise questions about the choice of the optimal orbital basis by considering finite basis sets, MCDHF orbitalbases and natural-orbital bases. We demonstrate the promising potential of the latter in the context of hyperfinestructures and hope that others will find interest in pursuing our analysis. Ultimately, our work put forward someweaknesses of the traditional optimization strategy based on the layer-by-layer optimization strategy.We also perform large-scale calculations to determine accurate atomic properties such as energy levels, hyperfinestructures, isotope shifts, transition parameters, radiative lifetimes and Landé g factors. We show through thevariety of atomic properties and atomic systems studied, the difficulty of describing, in the relativistic framework,the correlation between the spatial position of electrons due to their Coulomb repulsion.This thesis is organized in two main parts. The first one is dedicated to the theoretical and computationalbackgrounds that are needed to understand the theoretical models and the interpretation of our results. Thesecond part presents and summarizes our articles and manuscripts. They are separated in four groups, A, B, C,and D, around the themes of the atomic orbital bases, the applications to nuclear physics, the applications toastrophysics, and investigations of negative ions. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

The paper is located on the border between physics, mathematics and philosophy (ontology). The latter is required to embed the dualistic by nature mathematics into a monistic metatheory. It is shown, that a consequent philosophical monism and an approach which starts from the origin of the universe imposes significant constraints on a physical Theory-of-Everything. This may be helpful for finding such a theory. A philosophical system that is monistic and at the same time structured clear enough to be compatible with mathematical thinking is the Hegelian dialectic logic. With the aid of this logic the necessary existence of a causal chain embedded in the general, unconditional and timeless being is proved constructively. In the causal chain our entire reality is coded. It is termed by Hegel as determinate being in contrast to being. The chain has a beginning, representing the birth of the universe (big bang) and the beginning of time. It is isomorphic to the natural numbers. The half-ring structure of the natural numbers induces a secondary causal network. Thus the ontological approach results in a special version of the theory or causal sets. The causal network is topologically homeo-morphic to an infinite dimensional Minkowski cone. Each prime number corresponds to a dimension. Hypothetical small 'bumps” of 4D spacetime (Brane) in the direction of the extra dimensions of the Minkowski manifold mean topological defects, which can be interpreted as curvature of spacetime. This means a bridge to the general theory of relativity. On the other hand, the bumps may be interpreted as objects with which one can handle similar to the strings in string theory. / Die Arbeit bewegt sich im Grenzgebiet zwischen Physik, Mathematik und Philosophie (Ontologie). Letztere wird benötigt, um die vom Wesen her dualistische Mathematik in eine monistische Metatheorie einzubetten. Es wird gezeigt, dass ein konsequenter philosophischer Monismus und ein Denken vom Ursprung des Universums her einer physikalischen Theorie-von-Allem erhebliche Randbedingungen auferlegen. Für das Auffinden einer solchen Theorie kann das hilfreich sein. Ein philosophisches System, dass monistisch ist und zugleich klar genug strukturiert um mit der mathematischen Denkweise kompatibel zu sein ist die Hegelsche dialektische Logik. Unter Zuhilfenahme dieser Logik wird die notwendige Existenz einer in das allgemeine, unbedingte und zeitlose Sein eingebetteten, aber vom Chaos dieses Seins unbeeinflussten kausalen Kette konstruktiv bewiesen. In dieser kausalen Kette ist unsere gesamte Realität codiert, von Hegel als Dasein im Gegensatz zum Sein bezeichnet. Die Kette hat einen Anfang, der den Anfang des Universums und den Anfang der Zeit darstellt. Sie ist isomorph zu den natürlichen Zahlen. Deren Halbring-Struktur induziert ein sekundäres kausales Netzwerk. Somit ist das Ergebnis der ontologischen Herangehensweise eine spezielle Version der Theorie der kausalen Mengen. Das Netzwerk ist topologisch homöomorph ist zu einem unendlich dimensionalen Minkowski-Kegel. Jeder Primzahl entspricht eine Dimension. Hypothetische kleine „Ausbeulungen“ oder „Bumps“ der 4D-Raumzeit (Brane) in Richtung der Extradimensionen der Minkowski-Mannigfaltigkeit bedeuten topologische Baufehler, die sich als Krümmung der Raumzeit interpretieren lassen und eine Brücke zur allgemeinen Relativi-tätstheorie darstellen. Auf der anderen Seite lassen sich die Ausbeulungen der Brane als Objekte deuten, mit denen man ähnlich umgehen kann wie mit den Strings der Stringtheorie.

The main result of the thesis is the derivation of quantum phenomenological gravi- tational dynamics from the thermodynamics of local causal diamonds. By taking into account logarithmic corrections to entropy implied by quantum gravity effects, we derive new gravitational equations of motion which incorporate quantum corrections. The re- sulting theory appears to be a direct generalisation of the classical unimodular gravity instead of the general relativity. Upon obtaining the equations, we discuss their prop- erties and possible implications. As by-products, we also present a novel derivation of the Einstein equations from the thermodynamics of causal diamonds and a derivation of the logarithmic corrections to black hole entropy from the existence of minimal re- solvable area. Apart from the new results, we also provide an extensive review of the thermodynamics of local causal horizons. 1