Termodinâmica de um gás de fótons no contexto de eletrodinâmicas não-lineares

The objective of this dissertation is the development of a general formalism to analyze the thermodynamical properties of a photon gas under the context of nonlinear electrodynamics (NLED). To this end it is obtained, through the systematic analysis of Maxwell s electromagnetism (EM) properties, the general dependence of the Lagrangian that describes this kind of theories. From this Lagrangian and in the background of classical field theory, we derive the general dispersion relation that photons must obey in terms of a background field and the NLED properties. It is important to note that, in order to achieve this result, an aproximation has been made in order to allow the separation of the total electromagnetic field into a strong background electromagnetic field and a perturbation. Once the dispersion relation is in hand, the usual Bose-Einstein statistical procedure is followed through which the thermodynamical properties, energy density and pressure relations are obtained. An important result of this work is the fact that equation of state remains identical to the one obtained under EM. Then, two examples are made where the thermodynamic properties are explicitly derived in the context of two NLED, Born-Infelds and a quadratic approximation. The choice of the first one is due to the vast appearance in literature and, the second one, because it is a first order approximation of a large class of NLED. Ultimately, both are chosen because of their simplicity. Finally, the results are compared to EM and interpreted, suggesting possible tests to verify the internal consistency of NLED and motivating further developement into the formalism s quantum case

Bioquímica quântica na diferenciação dos níveis de ativação de receptores AMPA por agonistas parciais Wilardina

In the central nervous system (CNS) of mammalian, fast synaptic transmission between nerve cells is performed primarily by α-amino-3-hydroxy-5-methyl-4- isoxazolepropionic acid (AMPA) receptors, an ionotropic glutamate receptor that is related with learning, memory and homeostasis of the nervous system. Impairments in their functions are correlated with development of many brain desorders, such as epilepsy, schizophrenia, autism, Parkinson and Alzheimer. The use of willardiine analogs has been shown a powerful tool to understanding of activation and desensitization mechanisms of this receptors, because the modification of a single ligand atom allows the observation of varying levels of efficacy. In this work, taking advantage of Fluorine Willardiine (1.35Å), Hydrogen Willardiine (1.65Å), Bromine Willardiine (1.8Å) and Iodine Willardiine (2.15Å) structures co-crystalized with GluA2 with codes 1MQI, 1MQJ, 1MQH and 1MQG, we attempted to energetically differentiate the four ligands efficacy. The complexes were submitted to energetic calculations based on density functional theory (DFT), under the optics of molecular fractionation with conjugate caps (MFCC) method. Obtained results show a relationship between the energetic values and willardiines efficacy order (FW> HW > BrW > IW), also show the importance of E705, R485, Y450, S654, T655, T480 e P478 as the amino acids that contribute most strongly with the interaction of four partial agonists. Furthermore, we outlined the M708 behaviour, attracted by FW and HW ligands, and repels by BrW and IW. With the datas reported on this work, it is possible for a better understanding of the AMPA receptor, which can serve as an aid in the development of new drugs for this system.

Estudo da estrutura subsuperficial da província Borborema com correlação de ruído sísmico

Ambient seismic noise has traditionally been considered as an unwanted perturbation in seismic data acquisition that "contaminates" the clean recording of earthquakes. Over the last decade, however, it has been demonstrated that consistent information about the subsurface structure can be extracted from cross-correlation of ambient seismic noise. In this context, the rules are reversed: the ambient seismic noise becomes the desired seismic signal, while earthquakes become the unwanted perturbation that needs to be removed. At periods lower than 30 s, the spectrum of ambient seismic noise is dominated by microseism, which originates from distant atmospheric perturbations over the oceans. The microsseism is the most continuous seismic signal and can be classified as primary – when observed in the range 10-20 s – and secondary – when observed in the range 5-10 s. The Green‘s function of the propagating medium between two receivers (seismic stations) can be reconstructed by cross-correlating seismic noise simultaneously recorded at the receivers. The reconstruction of the Green‘s function is generally proportional to the surface-wave portion of the seismic wavefield, as microsseismic energy travels mostly as surface-waves. In this work, 194 Green‘s functions obtained from stacking of one month of daily cross-correlations of ambient seismic noise recorded in the vertical component of several pairs of broadband seismic stations in Northeast Brazil are presented. The daily cross-correlations were stacked using a timefrequency, phase-weighted scheme that enhances weak coherent signals by reducing incoherent noise. The cross-correlations show that, as expected, the emerged signal is dominated by Rayleigh waves, with dispersion velocities being reliably measured for periods ranging between 5 and 20 s. Both permanent stations from a monitoring seismic network and temporary stations from past passive experiments in the region are considered, resulting in a combined network of 33 stations separated by distances between 60 and 1311 km, approximately. The Rayleigh-wave, dispersion velocity measurements are then used to develop tomographic images of group velocity variation for the Borborema Province of Northeast Brazil. The tomographic maps allow to satisfactorily map buried structural features in the region. At short periods (~5 s) the images reflect shallow crustal structure, clearly delineating intra-continental and marginal sedimentary basins, as well as portions of important shear zones traversing the Borborema Province. At longer periods (10 – 20 s) the images are sensitive to deeper structure in the upper crust, and most of the shallower anomalies fade away. Interestingly, some of them do persist. The deep anomalies do not correlate with either the location of Cenozoic volcanism and uplift - which marked the evolution of the Borborema Province in the Cenozoic - or available maps of surface heat-flow, and the origin of the deep anomalies remains enigmatic.

O político nas imagens de A missão de Heiner Müller e O homem que era uma fábrica de Augusto Boal

Augusto Boal (Brasil) y Heiner Müller (Alemania) son dramaturgos del siglo XX que vivieron en países y contextos evidentemente distintos. Sin embargo, con la crisis del teatro burgués y de las condiciones de legitimidad del régimen de producción de este teatro, ambos presentan puntos de contacto en sus líneas y vectores teatrales que, frente a la universalidad cuestionable de la dramatización, llevan a la concepción de un teatro múltiple y perturbador del orden de lo sensible. Los procesos de escenificación contemporánea exige un adelantamiento del sentido político, desviando del juego de representaciones sociales, para dar lugar al trabajo deconstructor de imágenes como cisión entre la palabra y lo representado, entre lo legible y lo visible. Frente al expuesto, las escritas escénicas y, por eso, literarias de estos autores, sitios de singularización – no con ausencia de paradojas – capaces de movilizar manifestaciones e impases cuanto a las imágenes que ordenan o desordenan los textos dramáticos, traen para la contemporaneidad tensiones que llevan al teatro mismo, tanto a interpelarse como, en su fuerza plural, a encontrar pasajes para el nuevo. Llevar a la superficie aspectos políticos en las imágenes de los textos dramáticos, considerándolos en su inscripción literaria: “La misión: recuerdos de una revolución”, de Heiner Müller, y de “El hombre que era una fábrica”, de Augusto Boal, se hace un desafío, una vez que las imágenes pretendidas son aquellas con formas o materialidades todavía no visibles en la escena, podríamos decir, en estado virtual. Como imágenes pensantes, ellas suceden en el plan de inmanencia del lenguaje (Deleuze y Guattari). Siendo lo “político” una perturbación en lo sensible, contrario a la política (Rancière), la dramaturgia se abala en multiplicidades, desplazando y desnaturalizando las funciones de autor/dramaturgo y lector/actor, teatro/literatura. Dramaturgia simultánea, imagen, fragmento y colaje se muestran como procedimientos artísticos y literarios creativos que se encuentran apropiados sea en la teoría del teatro del oprimido (Boal), sea en el teatro pos-dramático (Hans-ThiesLehmann), a pesar de que, al confrontarlas, sobresalían en desentendimientos: la primera coincide con la lógica de la identidad y la segunda, esta se desarticula, movida por la diáfora, contestación, o desacuerdo. Tales relaciones – no apriorísticas – se suceden en cuanto acontecimiento de la lectura o de la literatura como acontecimiento en que lo político en las imágenes se da, antes, en las lagunas y obscuridades, aludiendo a lo que está más allá de lo sentido, de la escena del gesto y de la palabra. El lector no se para para atribuir sentido, se interroga frente a las metamorfosis y formas oblicuas de acontecimientos insospechables que componen lo político estableciendo la gestión colectiva de la enunciación. En este caso, el texto de Boal y el texto de Müller se inscriben en la producción de una literatura menor, o de un teatro menor, o que los califica como agentes de devenires revolucionarios, agitando, a través de la política en las imágenes, e irrumpiendo contra el problema del poder en las artes.