Dentro da área Ensino de Ciências identificamos diversos trabalhos que defendem a utilização de obras literárias no contexto de ensino-aprendizagem. Nesta pesquisa pretendemos contribuir com o diálogo entre a literatura e o ensino de ciências, utilizando referenciais da linguística e da linguagem na análise de três romances de ficção, escritos por físicos: -Sonhos de Einstein? de Alan Lightman (1992); -Tau Zero? de Poul Anderson (1970) e -O Tempo e o Espaço do Tio Albert? (1989) de Russel Stannard. O elemento motivador de nosso trabalho surge a partir das possibilidades da inserção da Física Moderna no ensino de física, assim como a possibilidade da interface entre Física e Literatura em sala de aula. Entretanto, como veremos adiante, o diálogo entre a física do início do século XX e as obras literárias é presente na obra de diversos autores, portanto havia a necessidade de um recorte temático que possibilitasse um recurso educacional para o ensino de física moderna. Dessa forma, a Teoria da Relatividade configura-se como uma teoria da física moderna que permite essa pesquisa por conta: do entendimento da TER como um fenômeno cultural; do diálogo histórico entre a Teoria da Relatividade e a Literatura; da necessidade de novos recursos para o ensino de TER e da exploração da TER para além dos conceitos. Os romances mencionados são caracterizados por tratar dos fenômenos inerentes à TER tanto em nível conceitual, quanto epistemológico. Portanto sua utilização no ensino de Física possibilita a discussão das esferas conceituais, sócio-histórica e filosófico-epistemológica em sala de aula. Para a análise da instância da produção e do discurso externo às obras, utilizaremos a análise de discurso derivada dos trabalhos de Mikhail Bakhtin, quanto à estrutura interna do texto, utilizamos a semiótica estruturalista de A.J. Greimas. A utilização da semiótica e da análise do discurso para analisar um romance a ser levado em sala de aula, possibilita identificar elementos textuais que auxiliem na construção dos conceitos junto aos estudantes. As diferentes percepções dos personagens se relacionam com as próprias ansiedades que a sociedade verifica na ciência, que dependendo da forma como é divulgada possui conotações eufóricas ou disfóricas. Além disso, a instância da produção do texto, que identifica o seu público-alvo e o discurso ideológico, possibilita a reflexão por questões sócio-históricas inerentes à ciência e ao papel do cientista. Quanto ao ensino de TER, tal análise, propicia uma reflexão sobre a abordagem dos conceitos e fenômenos relativísticos, norteando as novas visões sobre espaço e tempo que a teoria propõe. / It is possible to identify in Sciences Education several studies that advocate the use of literary works in the context of teaching and learning. In this research, we intend to contribute to the dialogue between literature and science teaching, using references from linguistics and language in the analysis of three fictional novels, written by physicists: \"Einstein\'s Dreams\" by Alan Lightman (1992); \"Tau Zero\" Poul Anderson (1970) and \"Time and Space of Uncle Albert\" (1989) by Russell Stannard. Our work motivation comes from the possibility of integration of modern physics in physics education, as well as the possibility of the interface between physics and literature in the classroom. However, as we shall see, the dialogue between the physics of the early twentieth century literary works and literature is present in the work of many authors, so there was need for a thematic focus that would enable an educational resource for teaching modern physics. Thus the special theory of relativity is configured as a theory of modern physics that enables this research because of: the understanding of the STR as a cultural phenomenon, the historical dialogue between the Theory of Relativity and Literature, the need for new resources for teaching STR and explored this theory beyond the concepts. The novels mentioned are characterized by treating the phenomena inherent in STR at both the conceptual and epistemological. Therefore its use in the teaching of physics allows the discussion of conceptual spheres, socio-historical and philosophical-epistemological classroom. For the analysis of the fictional text, we use benchmarks for Discursive Studies. For instance the analysis of speech production and external to the works, we use discourse analysis derived from the works of Mikhail Bakhtin, the internal structure of the text, use structuralist semiotics of AJ Greimas. The use of semiotics and discourse analysis to analyze a novel to be brought into the classroom enabling to identify textual elements, what helps in constructing the concepts together with students. As different perceptions of the characters relate to their own anxieties that society finds in science, depending on how it is disclosed has connotations euphoric or dysphoric. Furthermore, the instance of text production, identifying your target audience, as well as the ideological discourse, allows the reflection of socio-historical issues related to science and the scientific role. As for teaching STR, this analysis provides a reflection on the approach to relativistic concepts and relativistic phenomena, guiding the new views on space and time that the theory proposes.

Esta dissertação visa realizar um estudo acerca dos modelos de mundo brana no contexto proposto por Randall e Sundrum. O trabalho focaliza as perturbações de spin 0 no espaço-tempo de Kerr tomado como um mundo brana 4-dimensional. Para isso apresentamos os principais aspectos da Relatividade Geral de Einstein, bem como perturbações em métricas que descrevem buracos negros. Fizemos uma revisão dos modelos de Randall-Sundrum, suas motivações e tentativas de descrever buracos negros na brana. Por m a perturbação escalar da corda negra em rotação (Kerr-Randall-Sundrum) e o fenômeno de super-radiação são analisados. / This dissertation aims at studying the braneworld models in the context proposed by Randall and Sundrum. The focus is on the spin-0 perturbations in the Kerr space-time as a 4- dimensional braneworld. The work deals the main aspects of Einstein General Relativity as well as perturbations of black holes metrics. We also review the Randall-Sundrum models and their motivations and attempts to describe braneworld black holes. In the end the Kerr-Randall-Sundrum black string scalar perturbation and superradiance are obtained.

Extracting knowledge from user-generated content (UGC) in social media platforms is a very hot research topic in the area of machine learning, nonetheless, the main challenge resides in the fact that UGC carries inference, abstraction and subjectivity alongside objectivity. With the aim of recognising the importance of subjectivity as an influential aspect for providing humanoid results from a machine learning algorithm, this study proposes a novel approach to improve Instagram hashtag recommendation by considering sentiment that can be expressed for images. Two main points are studied in this thesis; evaluating the relativity of Instagram image to hashtag for both objective and subjective features of an image and the effect of sentiment on said relativity. This work examines three machine learning methods for hashtag recommendation: AWS service, developed algorithms with and without sentiment considerations. The models are tested on a collected dataset of de-identified Instagram posts in location London gathered from public profiles. The results show that considering sentiment significantly improves Instagram hashtag recommendation.

General relativity (GR) has stood as the most accurate description of gravity for the last 100 years, weathering a barrage of rigorous tests. However, attempts to derive GR from a more fundamental theory or to capture further physical principles at high energies has led to a vast number of alternative gravity theories. The individual examination of each gravity theory is infeasible and as such a systematic method of examining modified gravity theories is a necessity. Studying generic classes of gravity theories allows for general statements about observables to be made independent of explicit models. Take, for example, those models described by the Horndeski action, the most general class of scalar-tensor theory with at most second-order derivatives in the equations of motion, satisfying theoretical constraints. But these constraints alone are not enough for a given modified gravity model to be physically viable and hence worth studying. In particular, observations place incredibly tight constraints on the size of any deviation in the solar system. Hence, any modified gravity would have to mimic GR in such a situation. To accommodate this requirement, many models invoke screening mechanisms which suppress deviations from GR in regions of high density. But these mechanisms really upon non-linear effects and so studying them in complex models is mathematically complex. To constrain the space of actions of Horndeski type to those which pass solar-system tests, a set of conditions on the four free functions of the Horndeski action are derived which indicate whether a specific model embedded in the action possesses a GR limit. For this purpose, a new and surprisingly simple scaling method is developed, identifying dominant terms in the equations of motion by considering formal limits of the couplings that enter through the new terms in the modified gravity action. Solutions to the dominant terms identify regimes where nonlinear terms dominate and Einstein's field equations are recovered to leading order. Together with an efficient approximation of the scalar field profile, one can determine whether the recovery of Einstein's field equations can be attributed to a genuine screening effect. The parameterised post-Newtonian (PPN) formalism has enabled stringent tests of static weak-field gravity in a theory-independent manner. This is through parameterising common perturbations of the metric found when performing a post-Newtonian expansion. The framework is adapted by introducing an effective gravitational coupling and defining the PPN parameters as functions of position. Screening mechanisms of modified gravity theories can then be incorporated into the PPN framework through further developing the scaling method into a perturbative series. The PPN functions are found through a combination of the scaling method with a post-Newtonian expansion within a screened region. For illustration, we show that both a chameleon and cubic galileon model have a limit where they recover GR. Moreover, we find the effective gravitational constant and all PPN functions for these two theories in the screened limit. To examine how the adapted formalism compares to solar-system tests, we also analyse the Shapiro time delay effect for these two models and find no deviations from GR insofar as the signal path and the perturbing mass reside in a screened region of space. As such, tests based upon the path light rays such as those done by the Cassini mission do not constrain these theories. Finally, gravitational waves have opened up a new regime where gravity can be tested. To this end, we examine how the generation of gravitational waves are affected by theories of gravity with screening to second post-Newtonian (PN) order beyond the quadrupole. This is done for a model of gravity where the black hole binary lies in a screened region, while the space between the binary's neighbourhood and the detector is described by Brans-Dicke theory. We find deviations at both 1.5 and 2 PN order. Deviations of this size can be measured by the Advanced LIGO gravitational wave detector highlighting that our calculation may allow for constraints to be placed on these theories. We model idealised data from the black hole merger signal GW150914 and perform a best fit analysis. The most likely value for the un-screened Brans-Dicke parameter is found to be ω = -1:42, implying on large scales gravity is very modified, incompatible with cosmological results.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-12-20T16:23:34Z No. of bitstreams: 1 Feng Du_.pdf: 2029574 bytes, checksum: 4eb36acb7cf2e7ff3ef83c72262105ac (MD5) / Made available in DSpace on 2016-12-20T16:23:34Z (GMT). No. of bitstreams: 1 Feng Du_.pdf: 2029574 bytes, checksum: 4eb36acb7cf2e7ff3ef83c72262105ac (MD5) Previous issue date: 2016-09-16 / Nenhuma / The globally growth of smartphone sales seems inevitable, and it opens new challenges and opportunities for businesses. Understanding consumer behavior in smartphone purchase in a cross cultural context is important for both marketers and consumers. For the development of this research, a theoretical model was proposed and tested in order to understand the impact of consumer’s innovativeness and frugal behavior on smartphone purchase intention in a cross-cultural context. To this end, it was conducted a survey that covers analyzing the antecedents of innovativeness and frugal behavior, as well as understanding the cultural difference among consumer’s smartphone purchase intention. In detail, the survey was developed in Qualtrics and distributed to participants from three countries (Brazil, China and India). The valid sample size was 349 participants in total. We used structural equation modeling to verify the proposed model and analyze the collected data. After adjustment of theoretical model, the study results indicated satisfactory indexes. The final model showed that opinion leadership, product involvement and symbolic value are factors that positively lead to domain specific innovativeness; as well as intrinsic religiosity is positive antecedent of frugal behavior; materialism also positively related to frugal behavior under economic pressure background; both consumer’s domain specific innovativeness and frugal behavior are positively lead to smartphone purchase behavioral intention; the cultural orientation value such as collectivism, uncertainty avoidance and power distance have moderate effects on relations among consumer’s Innovativeness, frugal and behavioral intention; other moderators such as status consumption and economic strain also showed significant moderate effects in the final model.

The motion of neutral test particles, both massive and massless, in the space time of a charged source described by the Reissner-Nordström solution is studied. This solution is characterized by two parameters, mass and charge, which defines the horizons of the source. When the mass is larger than the charge, the solution describes a black hole, with two distinct horizons. When the mass and charge are equal there is an extremal black hole, and both horizons merge to one. Finally, when the charge is larger than the mass there is a naked singularity, with no horizon. The structure and properties of these different type of solution are presented and discussed. A general solution of the equations of motion is presented in function of the Weierstrass elliptic function ℘. In addition, the possible orbits for test particles are discussed, and the conditions for existence of closed, circular or escape orbits are presented. The classifications is made based on the particles energy, and the mass and charge of the source. We find that all mentioned orbits are allowed for the three different type of solutions. In particular, for extremal black holes and naked singularities, we find stable circular orbits located outside the event horizon and hence being visible for an external observer. / O movimento de partículas teste neutras, ambas massivas e sem massa, no espaço-tempo de uma fonte carregada descrita pela solução de Reissner-Nordström é estudada. Essa solução é caracterizada por dois parâmetros, massa e carga, que definem os horizontes da fonte. Quando a massa é maior que a carga tal solução descreve um buraco negro com dois horizontes distintos. Quando a massa e a carga são iguais há um buraco negro extremo, e ambos os horizontes se unem em um. Finalmente, quando a carga é maior que a massa, há uma singularidade nua, sem horizontes. A estrutura e as propriedades dessas diferentes soluções são apresentadas e discutidas. Uma solução geral da equação de movimento é apresentada em termos da função elíptica de Weierstrass, ℘. Além do mais as possiveis órbitas para uma partícula teste são discutidas, e as condições para existência de órbitas fechadas, circulares e de escape são apresentadas. A classificação é feita a partir da energia da partícula, e da massa e carga da fonte. Encontramos que todas as orbitas mencionadas são permitidas nos três diferentes tipos de soluções. Em partícular, para buracos negros extremos e singularidades nuas, encontramos órbitas circulares estáveis localizadas fora do horizonte de eventos e, consequentemente, sendo visível para observadores externos.

The abstract boundary construction of Scott and Szekeres has proven a practical classification scheme for boundary points of pseudo-Riemannian manifolds. It has also proved its utility in problems associated with the re-embedding of exact solutions containing directional singularities in space-time. Moreover it provides a model for singularities in space-time - essential singularities. However the literature has been devoid of abstract boundary results which have results of direct physical applicability.¶ This thesis presents several theorems on the existence of essential singularities in space-time and on how the abstract boundary allows definition of optimal em- beddings for depicting space-time. Firstly, a review of other boundary constructions for space-time is made with particular emphasis on the deficiencies they possess for describing singularities. The abstract boundary construction is then pedagogically defined and an overview of previous research provided.¶ We prove that strongly causal, maximally extended space-times possess essential singularities if and only if they possess incomplete causal geodesics. This result creates a link between the Hawking-Penrose incompleteness theorems and the existence of essential singularities. Using this result again together with the work of Beem on the stability of geodesic incompleteness it is possible to prove the stability of existence for essential singularities.¶ Invariant topological contact properties of abstract boundary points are presented for the first time and used to define partial cross sections, which are an generalization of the notion of embedding for boundary points. Partial cross sections are then used to define a model for an optimal embedding of space-time.¶ Finally we end with a presentation of the current research into the relationship between curvature singularities and the abstract boundary. This work proposes that the abstract boundary may provide the correct framework to prove curvature singularity theorems for General Relativity. This exciting development would culminate over 30 years of research into the physical conditions required for curvature singularities in space-time.

<p>Gravitational waves and electromagnetic waves are important as carriers of energy and information. This thesis is devoted to the study of the propagation and interaction of these waves in plasmas, with emphasis on nonlinear effects and applications within astrophysics.</p><p>The physical systems are described by the Einstein-Maxwell-fluid equations or Einstein-Maxwell-Vlasov equations, when a kinetic treatment is required. The small amplitude and high-frequency approximation is employed for the gravitational waves, such that perturbative techniques can be applied and space-time can be considered locally flat, with a gravitational radiation field superimposed on it. The gravitational waves give rise to coupling terms that have the structure of effective currents in the Maxwell equations and an effective gravitational force in the equation of motion for the plasma. The Einstein field equations describe the evolution of the gravitational waves, with the perturbed energy-momentum density of the plasma and the electromagnetic field as a source.</p><p>The processes that are investigated are gravitational waves exciting electromagnetic waves in plasmas, altering the optical properties of plasmas and accelerating charged particles. The thesis also deals with the propagation propertities of gravitational and electromagnetic waves, e.g. effects due to resonant wave-particle interactions, plasma inhomogeneties and nonlinear self-interactions. It is also shown that plasmas that are not in thermodynamical equilibrium may release their free energy by emitting gravitational waves.</p>

<p>Asymptotically flat spaces are widely studied because it is one natural way of describing an isolated system in general relativity. In this thesis we study what happens to the Lanczos potential at spacelike infinity in such spacetimes. By transformations of the Weyl-Lanczos equation, we derive expressions for the limiting equations on both the timelike unit hyperboloid, and the timelike unit cylinder. Finally the Newman-Penrose formalism is used to get a component version of the equations.</p>

One of the most exciting predictions of Einstein's theory of gravitation that have not yet been proven experimentally by a direct detection are gravitational waves. These are tiny distortions of the spacetime itself, and a world-wide effort to directly measure them for the first time with a network of large-scale laser interferometers is currently ongoing and expected to provide positive results within this decade. One potential source of measurable gravitational waves is the inspiral and merger of two compact objects, such as binary black holes. Successfully finding their signature in the noise-dominated data of the detectors crucially relies on accurate predictions of what we are looking for. In this thesis, we present a detailed study of how the most complete waveform templates can be constructed by combining the results from (A) analytical expansions within the post-Newtonian framework and (B) numerical simulations of the full relativistic dynamics. We analyze various strategies to construct complete hybrid waveforms that consist of a post-Newtonian inspiral part matched to numerical-relativity data. We elaborate on exsisting approaches for nonspinning systems by extending the accessible parameter space and introducing an alternative scheme based in the Fourier domain. Our methods can now be readily applied to multiple spherical-harmonic modes and precessing systems. In addition to that, we analyze in detail the accuracy of hybrid waveforms with the goal to quantify how numerous sources of error in the approximation techniques affect the application of such templates in real gravitational-wave searches. This is of major importance for the future construction of improved models, but also for the correct interpretation of gravitational-wave observations that are made utilizing any complete waveform family. In particular, we comprehensively discuss how long the numerical-relativity contribution to the signal has to be in order to make the resulting hybrids accurate enough, and for currently feasible simulation lengths we assess the physics one can potentially do with template-based searches. / Eine der aufregendsten Vorhersagen aus Einsteins Gravitationstheorie, die bisher noch nicht direkt durch ein Experiment nachgewiesen werden konnten, sind Gravitationswellen. Dies sind winzige Verzerrungen der Raumzeit selbst, und es wird erwartet, dass das aktuelle Netzwerk von groß angelegten Laserinterferometern im kommenden Jahrzehnt die erste direkte Gravitationswellenmessung realisieren kann. Eine potentielle Quelle von messbaren Gravitationswellen ist das Einspiralen und Verschmelzen zweier kompakter Objekte, wie z.B. ein Binärsystem von Schwarzen Löchern. Die erfolgreiche Identifizierung ihrer charakteristischen Signatur im Rausch-dominierten Datenstrom der Detektoren hängt allerdings entscheidend von genauen Vorhersagen ab, was wir eigentlich suchen. In dieser Arbeit wird detailliert untersucht, wie die komplettesten Wellenformenmodelle konstruiert werden können, indem die Ergebnisse von (A) analytischen Entwicklungen im post-Newtonschen Verfahren und (B) numerische Simulationen der voll-relativistischen Bewegungen verknüpft werden. Es werden verschiedene Verfahren zur Erstellung solcher "hybriden Wellenformen", bei denen der post-Newtonsche Teil mit numerischen Daten vervollständigt wird, analysiert. Existierende Strategien für nicht-rotierende Systeme werden vertieft und der beschriebene Parameterraum erweitert. Des Weiteren wird eine Alternative im Fourierraum eingeführt. Die entwickelten Methoden können nun auf multiple sphärisch-harmonische Moden und präzedierende Systeme angewandt werden. Zusätzlich wird die Genauigkeit der hybriden Wellenformen mit dem Ziel analysiert, den Einfluss verschiedener Fehlerquellen in den Näherungstechniken zu quantifizieren und die resultierenden Einschränkungen bei realen Anwendungen abzuschätzen. Dies ist von größter Bedeutung für die zukünftige Entwicklung von verbesserten Modellen, aber auch für die korrekte Interpretation von Gravitationswellenbeobachtungen, die auf Grundlage solcher Familien von Wellenformen gemacht worden sind. Insbesondere wird diskutiert, wie lang der numerische Anteil des Signals sein muss, um die Hybride genau genug konstruieren zu können. Für die aktuell umsetzbaren Simulationslängen wird die Physik eingeschätzt, die mit Hilfe von Modell-basierten Suchen potentiell untersucht werden kann.