This thesis investigates the interplay between explanatory issues in special relativity and the theory's metaphysical foundations. Special attention is given to the 'dynamical approach' to relativity, promoted primarily by Harvey Brown and collaborators, according to which the symmetries of dynamical laws are explanatory of relativistic effects, inertial motion, and even the Minkowskian geometrical structure of a specially relativistic world. The thesis begins with a review of Einstein's 1905 introduction to special relativity, after which brief historical introductions are given for the standard 'geometrical' approach to relativity and the unorthodox 'dynamical' approach. After a critical review of recent literature on the topic, the dynamical approach is shown to be in need of a metaphysical package that would undergird the explanatory claims mentioned above. It is argued that the dynamical approach is best understood as a form of relationalism - in particular, as a relativistic form of 'regularity relationalism', promoted recently by Nick Huggett. According to this view, some portion of a world's geometrical structure actually supervenes upon the symmetries of the best-system dynamical laws for a material ontology endowed with a primitive sub-metrical structure. To explore the plausibility of this construal of the dynamical approach, a case study is carried out on solutions to the Klein-Gordon equation. Examples are found for which the field values, when purged of all spatiotemporal structure but their induced topology, are still arguably best-systematized by the Klein-Gordon equation itself. This bolsters the plausibility of the claim that some system of field values, endowed with mere sub-metrical structure, might have as its best-systems dynamical laws a (set of) Lorentz-covariant equation(s), on which Minkowski geometrical structure would supervene. The upshot is that the dynamical approach to special relativity can be defended as what might be called an ontologically and ideologically relationalist approach to Minkowski spacetime structure. The chapters refer regularly to three appendices, which include a brief introduction to topological and differentiable spaces.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-10-10T19:33:25Z No. of bitstreams: 1 EDME VALE PEREIRA – DISSERTAÇÃO (PPGFísica) 2016.pdf: 765741 bytes, checksum: 06e478d901631d57a3c3905fb212d89c (MD5) / Made available in DSpace on 2018-10-10T19:33:25Z (GMT). No. of bitstreams: 1 EDME VALE PEREIRA – DISSERTAÇÃO (PPGFísica) 2016.pdf: 765741 bytes, checksum: 06e478d901631d57a3c3905fb212d89c (MD5) Previous issue date: 2016-08-11 / Capes / Neste trabalho, estudamos um escalonamento de Horava-Lifshitz destinado a reescrever uma eletrodinâmica que viola a invariância de Lorentz com operadores derivativos controlados por um quadrivetor constante n . Esse método foi usado inicialmente para escalonar a lagrangiana de Maxwell e depois a lagrangiana de altas ordens derivativas, conhecida como modelo Myers-Pospelov. Após o processo de escalonamento, obtivemos que ambas as lagrangianas são descritas em função de um expoente crítico z, que insere um caráter anisotrópico para ambas as teorias. Foram obtidos os propagadores de Feynman e as relações de dispersão para ambos os modelos. Devido ao caráter irrefringente atribuído ao modelo de altas ordens derivativas, usamos os modos de propagação associados, como as soluções por frequências, e efetuamos os cálculos de polarização para determinar os limites superiores de ocorrências dos efeitos da quebra da invariância de Lorentz. Tais operações estão de acordo com as observações de explosões de raios gama, mais especificamente, o evento GRB051218A. O parâmetro que controla a quebra da invariância de Lorentz, apresenta-se superior em 8 (oito) ordens de magnitude, se comparado com alguns resultados da literatura. O atraso temporal na propagação de dois fótons também foi determinado. / In this work, we study a Horava-Lifshitz scaling which can be used to rewrite an electrodynamics which breaks the Lorentz invariance with derivatives operators controlled by a constant four-vector, n . This method was initially used to scale the Maxwell lagrangian and then the high orders derivatives lagrangian, known as Myers-Pospelov model. After of the process, we obtained that both the lagrangian are described in terms of a critical exponent z, which can be inserted as anisotropic character for both theories. The of Feynman propagators and dispersion relations for both models were obtained. Due to the birefringent character attributed to Myers-Pospelov model, we use the associate propagation modes, as solutions for frequencies, and we perform the polarization calculations to determine the upper limits of occurrences related with e ects of Lorentz invariance breaking. Such operations are consistent with the recent observations of gamma-ray bursts, more speci cally, the GRB 051218A event. The parameter which controls of the Lorentz invariance violation, it presents superior in eight (8) orders of magnitude, compared with some results of literature. The time delay in the propagation of two photons was also determined.

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abstract: Researchers who conduct longitudinal studies are inherently interested in studying individual and population changes over time (e.g., mathematics achievement, subjective well-being). To answer such research questions, models of change (e.g., growth models) make the assumption of longitudinal measurement invariance. In many applied situations, key constructs are measured by a collection of ordered-categorical indicators (e.g., Likert scale items). To evaluate longitudinal measurement invariance with ordered-categorical indicators, a set of hierarchical models can be sequentially tested and compared. If the statistical tests of measurement invariance fail to be supported for one of the models, it is useful to have a method with which to gauge the practical significance of the differences in measurement model parameters over time. Drawing on studies of latent growth models and second-order latent growth models with continuous indicators (e.g., Kim & Willson, 2014a; 2014b; Leite, 2007; Wirth, 2008), this study examined the performance of a potential sensitivity analysis to gauge the practical significance of violations of longitudinal measurement invariance for ordered-categorical indicators using second-order latent growth models. The change in the estimate of the second-order growth parameters following the addition of an incorrect level of measurement invariance constraints at the first-order level was used as an effect size for measurement non-invariance. This study investigated how sensitive the proposed sensitivity analysis was to different locations of non-invariance (i.e., non-invariance in the factor loadings, the thresholds, and the unique factor variances) given a sufficient sample size. This study also examined whether the sensitivity of the proposed sensitivity analysis depended on a number of other factors including the magnitude of non-invariance, the number of non-invariant indicators, the number of non-invariant occasions, and the number of response categories in the indicators. / Dissertation/Thesis / Doctoral Dissertation Psychology 2016

We introduce the historical context and motivation for the search for magnetic monopoles or monopole-like objects. Beginning the theoretical part we investigate the properties of groups as they relate to symmetries in physical theories. Using this as a basis we investigate the requirements for global and local gauge invariance for a scalar field, the latter giving the non-trivial connection to a gauge field. From this we present the Georgi-Glashow model and develop its particle spectrum using the connected Higgs field and its associated Higgs mechanism. We then present the electromagnetic duality by extending the Maxwell's equations toinclude magnetic sources. Using the assumption of magnetic sources we present the Dirac quantization condition, motivating the quantization of electric charge. Returning to our model we present the 't Hooft-Polyakov ansatz and investigate its defining properties as a finite energy soliton in our Higgs field. We show the magnetic properties and motivate its validity as a monopole like object. Continuing we define BPS-states on the lower bound for the mass of a monopole like object with magnetic and electric charge. Giving a BPS monopole as a solution in the vein of 't Hooft and Polyakov. Returning to the electromagnetic duality we propose the Montonen-Olive conjecture by exchanging massive vector bosons in our model with the BPS monopoles we developed. We shortly comment on evident problems and present supersymmetry as a possible solution. Finally we present the Witten Effect by allowing a CP violating term in our Lagrangian. From this we extend the Montonen-Olive conjecture to include invariance under the SL(2,Z) group.

abstract: Investigation of measurement invariance (MI) commonly assumes correct specification of dimensionality across multiple groups. Although research shows that violation of the dimensionality assumption can cause bias in model parameter estimation for single-group analyses, little research on this issue has been conducted for multiple-group analyses. This study explored the effects of mismatch in dimensionality between data and analysis models with multiple-group analyses at the population and sample levels. Datasets were generated using a bifactor model with different factor structures and were analyzed with bifactor and single-factor models to assess misspecification effects on assessments of MI and latent mean differences. As baseline models, the bifactor models fit data well and had minimal bias in latent mean estimation. However, the low convergence rates of fitting bifactor models to data with complex structures and small sample sizes caused concern. On the other hand, effects of fitting the misspecified single-factor models on the assessments of MI and latent means differed by the bifactor structures underlying data. For data following one general factor and one group factor affecting a small set of indicators, the effects of ignoring the group factor in analysis models on the tests of MI and latent mean differences were mild. In contrast, for data following one general factor and several group factors, oversimplifications of analysis models can lead to inaccurate conclusions regarding MI assessment and latent mean estimation. / Dissertation/Thesis / Doctoral Dissertation Educational Psychology 2018

Neste trabalho, discutem-se aspectos das transformações conformes na eletrodinâmica clássica com ênfase na invariância e nas leis de conservação. Inicialmente, abordaram-se aspectos gerais das transformações conformes e fez-se um resumo histórico da evolução dessas transformações. Procurou-se fazer uma apresentação didática, revisando-se a formulação Lagrangiana e o Teorema de Noether para campos aplicado à eletrodinâmica. Estudaram-se as transformações conformes no espaço plano, onde se mostrou que para dimensões maiores ou iguais a três o número de transformações é finito. A partir das equações de Maxwell em coordenadas curvilíneas, chegou-se à condição para que essas equações mantivessem sua forma cartesiana. Com essa condição, mostrou-se que a eletrodinâmica clássica é invariante para o grupo de transformações conformes. Foram discutidas as leis de conservação associadas à invariância conforme da eletrodinâmica clássica a partir do teorema de Noether. Das simetrias por translações no espaço-tempo, obtiveram-se as leis de conservação do momento linear e da energia. Das simetrias associadas às rotações, obtiveram-se seis quantidades conservadas: três delas ligadas à conservação do momento angular e, com relação às três restantes, observou-se, a partir de analogias com a mecânica, que estavam associadas ao movimento do centro de energia do campo. Para a interpretação da grandeza conservada por simetria de escala, verificou-se, também a partir de uma analogia mecânica, que essa simetria somente é verificada para partículas não massivas ou para partículas massivas a altas energias. Finalmente, para as transformações conformes especiais, verificou-se que as leis de conservação resultantes são consequências das leis anteriores de conservação para o campo eletromagnético, e neste caso, essa simetria também somente se manifesta para partículas de massa nula ou para altas energias. / In this work, aspects of conformal transformations in classical electrodynamics are discussed with emphasis on the invariance and conservation laws. Initially, a general view of conformal transformations was shown and a summary of the historical evolution of those transformations was presented. The work was approached didactically, and Noethers theorem based on the electrodynamics Lagrangian formulation was revised. The conformal transformations were studied in plane spaces and it was shown that, for dimensions greater than or equal to three, the number of transformations is finite. Starting from Maxwells equations in curvilinear coordinates, a condition for maintaining those equations in Cartesian form was established. With that condition, it was shown that the classical electrodynamics laws are invariant for the group of conformal transformations. The conservation laws associated with the conformal invariance of classical electrodynamics were discussed, based on Noethers theorem. From the space-time translation symmetry, the laws of conservation of linear momentum and of energy were obtained. From rotational symmetry, six conserved quantities were obtained: three of them associated with angular momentum and the remaining three, observed, starting from analogies with mechanics, were associated with the movement of the center of energy of the field. For the interpretation of the quantity conserved by scale symmetry, it was verified, also from a mechanical analogy, that that symmetry is only valid for null mass particles or for high energies. Finally, for the special conformal transformations, it was verified that the resultant laws of conservation are consequences of the previous laws, and in that case, symmetry is also valid only for particles of null mass or for high energies.

Nesta tese estudamos as propriedades críticas dos modelos anisotrópicos (isotrópicos) de Heisenberg com spin s arbitrário. O espectro das Hamiltonianas, com condições periódicas de contorno, foi calculado para redes finitas, resolvendo-se as equações do Bethe ansatz associadas. Nossos resultados indicam que a anomalia conforme destes modelos tem o valor c=3s/(1+s), independente da anisotropia, e os expoentes críticos variam continuamente com a anisotropia assim como no modelo de 8-vértices. O conteúdo de operadores destes modelos indica que a teoria de campos que governa a criticalidade destes modelos de spin é descrita por operadores formados pelo produto de um operador Gaussiano por outro com simetria Z(2s). Estudando estes modelos, com certas condições especiais de contorno, mostramos que eles são relacionados com uma nova classe de teorias unitárias recentemente propostas / This thesis is concerned with the critical properties of anisotropic (isotropic) Heisenberg chain,with arbitrary spin-s. The eigenspectrum of these Hamiltoniana, with periodic boundaries, are calculated for finite chains by solving numerically their associated Bethe ansatz equations. The results indicate that the conformal anomaly hás the value c=3s/1+s, independently of the anisotropy, and the exponentes vary continuously with the anisotropy like in the 8-vertex model. The operator content of these models indicate that the underlying field theory governing these critical spin-s models are described by composite fields formed by the product of Gaussian and Z(2s) fields. Studying these models, with some special boundary conditions, we show that they are related with a large class of unitary conformal field theories recntly introduced

As técnicas de análise de estabilidade transitória em sistemas elétricos de potência desenvolveram-se significativamente nas últimas duas décadas. Atualmente, o principal desafio dos pesquisadores é a obtenção de técnicas que sejam adequadasa análises em tempo real. Neste sentido, as idéias de Liapunov associadas ao Princípio de Invariância de LaSalle têm sido utilizadas para estimar a bacia de atraçãoo dos sistemas de potência. Embora esta filosofia seja bastante adequada a análises de estabilidade em tempo real, existem alguns obstáculos que impedem a aplicação da mesma à análise de sistemas reais. Dentre estes obstáculos poder-se-ia destacar a impossibilidade de utilização de modelos mais realísticos e a limitação da análise ao primeiro "swing". Em verdade, estes obstáculos estão intimamente relacionados com as limitações do Princípio de Invariância de LaSalle. Para superar estes problemas, propõe-se, neste trabalho, uma extensão deste princípio que é mais geral e portanto mais flexível do que o original. Aproveitando esta maior flexibilidade, duas aplicações em análise de estabilidade transitória são abordadas, ambas com o objetivo de reduzir os obstáculos anteriormente mencionados. Na primeira, propõe-se uma nova função energia para sistemas de potência com perdas nas linhas de transmissão. Mostra-se que esta é uma função de Liapunov no sentido mais geral da extensão do Princípio de Invariância de LaSalle, podendo portanto ser empregada para estudos de estabilidade. Na segunda, uma metodologia de análise de estabilidade multi-"swing" é proposta com base em uma análise de coerência de geradores.

Muitos sistemas físicos são modelados por sistemas dinâmicos discretos. Com o advento da tecnologia digital os sistemas discretos tornaram-se ainda mais importantes, sendo assim, o desenvolvimento de ferramentas analíticas para este tipo de sistema é de grande importância. Neste trabalho, estudam-se alguns dos principais resultados relacionados à estabilidade de sistemas dinâmicos discretos, e alguns novos são propostos. É bem conhecido na literatura que a estabilidade de um ponto de equilíbrio pode ser caracterizada pelo Método Direto de Lyapunov, via uma função auxiliar denominada função de Lyapunov. LaSalle, ao estudar a teoria de Lyapunov, estabeleceu uma importante relação entre função de Lyapunov e conjuntos limites de Birkhoff, que deu origem ao Princípio de Invariância de LaSalle. Este, entre outras coisas, permite a análise de estabilidade assintótica. Tanto o Método Direto de Lyapunov quanto o Princípio de Invariância requerem que a variação da função de Lyapunov seja não positiva ao longo das trajetórias do sistema. Em sistemas com comportamentos mais complexos, dificilmente encontra-se uma função com esta propriedade. Neste trabalho, propõe-se uma versão mais geral do Princípio de Invariância para sistemas discretos, a qual não exige que a variação da função de Lyapunov seja sempre não positiva. Com isto, a obtenção de funções deste tipo torna-se mais simples e muitos problemas, que antes não poderiam ser tratados com a teoria convencional, passam a ser tratados através deste novo resultado. Os resultados desenvolvi- dos, neste trabalho, são úteis para encontrar estimativas de atratores de sistemas não-lineares discretos. / Many physical systems are modeled by discrete dynamic systems. With the evolution digital technology, the discrete systems became still more important, so the development of analytic tools for this type of system has high importance nowadays. ln this work, some of the main results in stability of discrete dynamic systems are studied and some new ones are proposed. lt is well known in the literature that the stability of an equilibrium point may be characterized by the Lyapunov\'s Direct Method, with a function known as Lyapunov auxiliary function. LaSalle, when studying the Lyapunov theory, established an important relationship between Lyapunov function and Birkhoff limit sets. Then, he created the Lasalle\'s lnvariance Principle. This, among other features, allows the analysis of asymptotically stability. Both the Lyapunov\'s Direct Method and the lnvariance Principle request the variation of the Lyapunov function to be negative semidefinite along the system trajectory. In systems with more complex behaviors, a function is hardly found with this property. This work developed a more general version of the lnvariance Principle for discrete systems, which does not require the variation of the Lyapunov function to be always negative semidefinite. This new theory enables to find these functions easily and many insoluble problems, which could not be treated with the conventional theory before, become treatable by this new result. The results of this work are useful to find estimates of discrete nonlinear systems atractors.