Os sistemas biológicos interagem com o ambiente em que vivem de muitas formas, e uma das principais formas na qual essa interação se dá é pela transmissão de mensagens, de diversas maneiras. A transmissão de mensagens por vias sonoras, em animais, é uma questão muito abordada em muitos estudos por ser uma importante via de comunicação utilizada por diversos tipos de sistemas biológicos. Este trabalho tem como objetivo verificar, pelo viés da Teoria da Informação de Shannon, se através da organização das séries temporais referentes à comunicação é possível observar a diminuição de geração de entropia no sistema nervoso referente ao processamento dos sinais sonoros de comunicação. Para tanto, utilizou-se, como sistemas-modelo, três espécies de anuros, Scinax perpusillus e Hypsiboas faber e Hypsiboas pardalis. Ferramentas de análise não-lineares, como a Entropia Aproximada Volumétrica, Análise de Potência Espectral e Plot de Poincaré, foram utilizados para caracterizar a variabilidade tanto do sinal emitido por um único animal quanto dos sinais trocados entre indivíduos da mesma espécie. Foi verificado que as séries temporais analisadas são altamente variáveis, com os intervalos entre vocalizações sendo descritos por distribuições de Lévy. As séries temporais relativas à interação entre indivíduos da mesma espécie apresentam uma alta variabilidade, porém menor que as individuais. Devido ao controle neural exercido na vocalização em anuros, é possível que a variabilidade apresentada pelas séries otimize o processo de emissão sonora, diminuindo a sobreposição de vocalizações entre indivíduos. A diminuição da variabilidade da interação entre indivíduos pode ser um indicativo da diminuição da geração de entropia no processo de comunicação destes animais. / Biological systems interact with their environment in many forms. The way these interactions occur can be assigned, ultimately, as the transmission of messages. Transmission of messages by sound waves, in animals, is a well studied subject because they are an important way of communication used by many groups. The objective of the present work is to verify whether the central nervous system presents entropy generation minimization in processing communicating sound signals. The approach employed is derived from Shannons Information Theory. The temporal organization of the time intervals between successive vocalizations was the subject of analysis. Recordings of three anuran species, Scinax perpusillus, Hypsiboas faber and Hypsiboas pardalis were used. Non-linear analyses were performed by tools as Volumetric Approximated Entropy, Power Spectrum Analysis and Poincaré Plot in order to address the variability of the signals emitted by a single animal, as well as the signals exchanged among individuals of the same species. The time-series data analyzed present highly variability and can be adequately described by Lévys distributions. The time-series data of the interactions among individuals also present high variability, however such a variability is not as high as the variability of single individuals. The results suggest that the neural system works in a way that reduces the probability of vocalizations overlapping. The reduction in variability of the interactions among individuals is, perhaps, linked to a minimization of entropy generation in the communication process of these animals.

Estudamos o efeito de uma tangência homoclínica na variação da entropia topológica. Provamos que um difeomorfismo com uma tangência homoclínica associada a uma peça básica com máxima entropia é um ponto de variação da entropia na topologia \'C POT. INFINITO\'. Além disso, discutimos o problema variacional na topologia \'C POT.1\' e apresentamos um exemplo de descontinuidade da entropia em dimensão três. Um resultado devido a Newhouse afirma que um difeomorfismo genérico sobre uma superfície com um conjunto homoclínico que contém uma tangência correspondente a um ponto periódico dissipativo, não pode ter medidas de SRB suportadas no conjunto homoclínico. Generalizamos este resultado para dimensões maiores, no caso em que a tangência homoclínica está associada com uma sela seccionalmente dissipativa / We study the effect of a homoclinic tangency in the variation of the topological entropy. We prove that a diffeomorphism with a homoclinic tangency associated to a basic hyperbolic set with maximal entropy is a point of entropy variation in the \'C POT THE INFINITE\' topology. We also discuss variational problem in \'C POT.1\' topology and we show an example of discontinuity of the entropy in dimension three. A result due to Newhouse states that a generic surface diffeomorphism with a homoclinic set containing a tangency associated to a dissipative periodic point, can not have SRB (Sinai-Ruelle-Bowen) measures supported on the homoclinic set. We generalize this result to higher dimensions, in the case where the homoclinic tangency is associated to a sectionally dissipative saddle

A introdução de uma nova expressão matemática para a entropia permite construir novos ensembles na Teoria das Matrizes Aleatórias. Neste trabalho, apresenta-se uma estrutura geral para construção de todos os possíveis ensemble. Portanto, os elementos das matrizes podem ser números reais, complexos ou mesmo quaternions. O principio da entropia (não-extensiva) máxima e o Cálculo Variacional são usados para realizar essa façanha. Esta tese está comprometida com a construção do Ensemble Ortogonal Generalizado, cujas matrizes aleatórias são simétricas e seus elementos são os números reais, especificamente. As distribuições das matrizes, as distribuições de um elemento da matriz e as estatísticas espectrais são obtidas, estudadas e os resultados apresentados. / The introduction of a new mathematical expression for the entropy allows the construction of new ensembles in Random Matrices Theory. A general structure is presented to the construction of all possible ensembles. Therefore the matrix\'s elements can be real numbers, complex numbers or even quaternions. The generalized of the maximum entropy (nonextensive) principle and the variational calculus are to use to realize this achievement. This thesis concerned with the construction of the Generalized Orthogonal Ensemble, whose random matrices are symetric and its elements are real numbers. The matrix distribuit ion, the distribuition of an element of the matrix and the spectrum statistical were to obtained, studied and the results presented.

Apresenta-se uma definição de sustentabilidade baseada na segunda lei da termodinâmica e mostra-se que, a partir essa definição, é possível desatrelar o crescimento econômico do uso dos recursos naturais, a fim de evitar que as forças do mercado se oponham a uma reestruturação do setor energético que tenha o objetivo de passar da atual matriz energética, que é insustentável, para uma que o seja usando apenas as fontes renováveis de energia de que o Brasil dispõe. A transição da matriz insustentável para uma sustentável implicará uma crescente racionalização do consumo, paralelamente ao emprego de energias renováveis e à redução do emprego de fontes não renováveis, tais como o petróleo e o gás natural. A partir de meados do presente século, a adaptação dos padrões de consumo e o desenvolvimento tecnológico permitirão que o emprego de fontes renováveis vá deslocando mais rapidamente as fontes não-renováveis, levando-as a uma posição tendente à anulação até o fim do século. No corpo da tese discute-se o emprego do princípio da precaução no planejamento energético e demonstra-se que o Brasil tem condições para se tornar praticamente independente de fontes não-renováveis de energia. / Starting with a definition of sustainability based on the entropy law, which enable us to proceed a decoupling of economic growth and exploitation of natural resources, we demonstrate that Brazil has enough renewable energy sources to move away from the present energy matrix, which is unsustainable, to a sustainable one, through a transition process based on the increasing use of renewable energies and rationalization of consumption, simultaneously with gradual decrease in the use of non-renewable energies such as oil and natural gas. From the middle of this century on, the use of non-renewable sources should decrease more rapidly, approaching a marginal position at the end of the century. In the thesis it is discussed the precaution principle in energy planning and it is proved that Brazil has the necessary material conditions to become practically independent of non-renewable energy sources.

Recentemente, uma quantidade de informação/computação quântica chamada complexidade computacional tem adquirido mais e mais importância no estudo de buracos negros.Resumidamente, complexidade mede a dificuldade de alguma tarefa. No contexto de mecânica quântica (ou mesmo para estados em uma CFT), qualquer estado tem uma complexidade associada, uma vez que o processo de preparar algum estado, usando operações unitárias, é uma tarefa por sí só. Propostas holográficas para o cálculo de complexidade tem sido desenvolvidas nos anos recentes. Há duas delas que estão mais desenvolvidas: as conjecturas complexidade=volume e complexidade=ação. No contexto da correspondência AdS/CFT é sabido que o buraco negro de Schwarzschild em AdS é dual à um estado térmico que descreve duas CFTs emaranhadas. Para esse caso em específico, a conjectura complexidade=volume iguala a complexidade do estado que descreve esse par de CFTs emaranhadas com o volume da máxima superfície de codimensão um no espaço-tempo dual. Por outro lado, a conjectura complexidade=ação iguala a complexidade da borda com a ação gravitacional calculada sobre uma região do espaço-tempo conhecida como Wheeler-DeWitt patch. O objetivo dessa tese é proporcionar os requisitos necessários para entender as conjecturas relacionadas com complexidade, monstrando alguns resultados importantes proporcionados pelos cálculos holográficos no lado gravitacional. / In recent years, a quantity from quantum information/computation called computational complexity has been acquiring more and more importance in the study of black holes. Briefly, complexity measures the hardness of some task. In the context of quantum mechanics (or even for states in a CFT), any state has an associated complexity, once the process of to preparing some state, using unitary operations, is a task by itself. Holographic proposals for the computation of complexity have been developed in recent years. There are two of them that are more developed: the complexity=volume and complexity=action conjectures. In the context of the AdS/CFT correspondence, it is known that the two sided AdS-Schwarzschild black hole is dual to some thermal state that describes two entangled CFTs. For this specific case, the complexity=volume conjecture equates the complexity of the state that describes this pair of entangled CFTs with the volume of the maximal codimension-one surface in the dual space-time. On the other hand, the complexity=action conjecture equates the boundary complexity with the gravitational action evaluated on a region of space-time known as the Wheeler-DeWitt patch. The goal of this thesis is to provide the necessary requisites to understand the conjectures related to complexity, showing some important results provided by holographic computations on the gravitational side.

Following a call from Linton (2010) to think more relationally about water this thesis seeks to explore the infolding and unfolding relations that take-form between bodies around particular characteristics of freshwater. There is a tradition of exploration regarding the sustainability, quality, monitoring and management of water when we encounter research on human associations with fluvial hydrology, and whilst this work is important, this project looks to enrol more nascent and contemporary geographical themes to broaden our understanding of encounters with freshwater landscapes, and take a more relational approach to fluvial geographies. These works then shall address a gap in the geographical literature and describe the personal, pre-personal and affective worlds that emerge when bodies become down by the river. Whilst this is not specifically a walking project, walking the course of the River Severn serves as a trajectory along which processual ideas of bodies on the move shall be mobilised. A series of creatively written segues will link together a sequence of theoretical and conceptually driven site ontologies (Marston et al 2005; Woodward et al 2010) and relations associated with the Severn and freshwater more broadly. The flow and form of the thesis will reflect the multivariant characteristics of water and its varying speeds and slownesses. The chapters will step into puddles, mooch about in a ships graveyard, rethink the source of a river, paddle a coracle and set the scene for how an ontological, relational approach to fluvial landscapes can contribute to geographical thinking. The works will focus on human-nonhuman relations, vibrant materialities and elemental mobilities, in so doing enable further understanding of how we can apprehend sites as moments of coherence in a turbulent world, and contribute to broadening our scope of knowledge of the more-than-human.

We evaluate the security of human voice password databases from an information theoretical point of view. More specifically, we provide a theoretical estimation on the amount of entropy in human voice when processed using the conventional GMM-UBM technologies and the MFCCs as the acoustic features. The theoretical estimation gives rise to a methodology for analyzing the security level in a corpus of human voice. That is, given a database containing speech signals, we provide a method for estimating the relative entropy (Kullback-Leibler divergence) of the database thereby establishing the security level of the speaker verification system. To demonstrate this, we analyze the YOHO database, a corpus of voice samples collected from 138 speakers and show that the amount of entropy extracted is less than 14-bits. We also present a practical attack that succeeds in impersonating the voice of any speaker within the corpus with a 98% success probability with as little as 9 trials. The attack will still succeed with a rate of 62.50% if 4 attempts are permitted. Further, based on the same attack rationale, we mount an attack on the ALIZE speaker verification system. We show through experimentation that the attacker can impersonate any user in the database of 69 people with about 25% success rate with only 5 trials. The success rate can achieve more than 50% by increasing the allowed authentication attempts to 20. Finally, when the practical attack is cast in terms of an entropy metric, we find that the theoretical entropy estimate almost perfectly predicts the success rate of the practical attack, giving further credence to the theoretical model and the associated entropy estimation technique.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by John Adam Keklak. / M.S.

Automatic reading comprehension (RC) systems integrate various kinds of natural language processing (NLP) technologies to analyze a given passage and generate or extract answers in response to questions about the passage. Previous work applied a lot of NLP technologies including shallow syntactic analyses (e.g. base noun phrases), semantic analyses (e.g. named entities) and discourse analyses (e.g. pronoun referents) in the bag-of-words (BOW) matching approach. This thesis proposes a novel RC approach that integrates a set of NLP technologies in a maximum entropy (ME) framework to estimate candidate answer sentences' probabilities being answers. In contrast to previous RC approaches, which are in English-only, the presented RC approach is the first one for both English and Chinese, the two languages used by most people in the world. In order to support the evaluation of the bilingual RC systems, a parallel English and Chinese corpus is also designed and developed. Annotations deemed relevant to the RC task are also included in the corpus. In addition, useful NLP technologies are explored from a new perspective---referring the pedagogical guidelines of humans, reading skills are summarized and mapped to various NLP technologies. Practical NLP technologies, categorized as shallow syntactic analyses (i.e. part-of-speech tags, voices and tenses) and deep syntactic analyses (i.e. syntactic parse trees and dependency parse trees) are then selected for integration. The proposed approach is evaluated on an English corpus, namely Remedia and our bilingual corpus. The experimental results show that our approach significantly improves the RC results on both English and Chinese corpora. / Xu, Kui. / Adviser: Helen Mei-Ling Meng. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3618. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 132-141). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

by Wen Jiang. / c.2 author's name on frame header: Wen, Jiang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (p. 105-[113]). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.