Foi aplicado à geometria anular um tratamento matemático para análise e projeto de circuladores planares que faz uso das funções de Green para estruturas planares generalizadas com condições de contorno contínuas na fronteira ferrita-dielétrico. Com base no tratamento acima, foi projetado um circulador de ferrita com núcleo anular em estrutura "Stripline" e construiu-se um protótipo que apresentou desempenho, na melhor das portas, de: 0,25 dB de perda de inserção, com largura de faixa de 16% na frequência de circulação de 2.544 GHz e com isolação não inferior a 20 dB. Operou-se na frequência em que a permeabilidade magnética efetiva é aproximadamente igual a zero - abaixo do nível de saturação da ferrita, - com campo magnetizante externo de 880 Oe. Os resultados obtidos encorajam a previsão do desenvolvimento de circuladores anulares em estrutura "Stripline" com circuito de magnetização miniaturizada que apresentarão desempenho competitivo com os de núcleo circular. É também apresentada uma extensão dessa "análise de Miyoshi" para permeabilidade magnética efetiva menor ou igual a zero, bem como é fornecido um programa computacional para auxílio ao dimensionamento do dispositivo.

este trabalho são analisadas antenas de microfita retangulares, alimentadas por prova de corrente e moldadas sobre superfícies cilíndricas, utilizando-se o modelo da cavidade ressonante e a técnica da transformada dupla de Fourier. Inicialmente, expressões gerais para os campos irradiados por uma abertura eletromagnética em um cilindro perfeitamente condutor e de comprimento infinito são estabelecidas no domínio de Fourier. Formas assintóticas para os campos distantes são também determinadas empregando-se o método da fase estacionária. Os campos eletromagnéticos irradiados por uma antena de microfita retangular conformada sobre uma superfície cilíndrica são determinados usando-se um modelo equivalente constituído por uma rede de quatro fendas retangulares localizadas ao longo de sua circunferência. Diagramas de irradiação para os dois modos dominantes TM10 e TM01 são traçados e discutidos. Utilizando-se a formulação desenvolvida são determinadas expressões para o cálculo da impedância de entrada e da razão axial da onda irradiada pela antena. Equações para a síntese de antenas circularmente polarizadas são também estabelecidas. Um exemplo de aplicação é apresentado para o caso de uma antena operando em 2,25 GHz, que se encontra dentro da faixa alocada para telemetria de veículos espaciais. Em seguida apresenta-se a análise de redes de antenas moldadas em superfícies cilíndricas. O efeito do acoplamento entre duas antenas linearmente polarizadas é estudado através do cálculo da impedância mútua entre dois desses elementos. As expressões para os campos irradiados por redes de antenas conformadas são estabelecidas e diagramas de irradiação são traçados para várias configurações de redes circularmente polarizadas. Experimentos realizados na freqüência de 2,25 GHz são discutidos e seus resultados comparados com a teoria. São apresentadas medidas de impedância de entrada e de diagramas de irradiação para o caso de uma antena retangular circularmente polarizada moldada sobre uma superfície cilíndrica, verificando-se boa concordância entre resultados teóricos e experimentais. O projeto e a medida da impedância de entrada de duas redes circularmente polarizadas conformadas sobre uma superfície cilíndrica são descritos. Fotografias dos protótipos construídos são apresentadas ao longo do trabalho.

Um novo método para avaliação do tamanho de gotas de chuva e sua distribuição é apresentado. O método é baseado no processamento de imagens com o uso da transformada de Hough circular em conjunto com as técnicas de Backmapping e análise de vizinhança. Esta metodologia trás vantagens, uma vez que viabiliza medidas diretas e de forma automática para identificação e contagem de gotas de chuva. A calibração do método foi desenvolvida utilizando padrões de gotas conhecidos. Gotas, na faixa de 1 &#956m a 85 mm de diâmetro, foram automaticamente reconhecidas e medidas com sucesso. Resultados mostram erro médio percentual não maior que 3,61%. Adicionalmente é apresentado uma comparação de resultados obtidos com um método de análise de correlação em frequência e contagem direta. Resultados mostram a potencialidade da metodologia desenvolvida para aplicações agrícolas. / A new method for evaluating raindrop size and distribution has been developed. It is based on image processing with circular Hough fast transform composed with the Backmapping and neighborhood analysis techniques. This methodology has the advantage of being a direct measurement method that automatically identifies and counts raindrops. Calibration was carried out using standard patterns with known raindrop sizes. Drops sizes ranging from 1 &#956m sizes to 85 mm in diameter has been automatically recognized and successfully measured. Results show perceptual average error not larger than 3,61%. In addition a comparison of results with the correlation analysis in the frequency domain and directed counts methods are presented. Results show the suitability of developed methodology.

Resumo: Peptídeos bioativos são de elevado interesse como substitutos de antibióticos convencionais já que alguns destes apresentam atividade antimicrobiana. Eles são predominantemente catiônicos e tem sido mostrado que sua atividade antimicrobiana é modulada por interações eletrostáticas, hidrofóbicas e por características elásticas das membranas, seu alvo. Neste trabalho analisou-se a importância da carga elétrica líquida (Q) e hidrofobicidade na interação de quatro peptídeos com membranas modelo de caráter aniônico e zwitteriônico utilizando medidas de potencial eletrocinético, dicroísmo circular e espectroscopia de fluorescência. Estes peptídeos denominados mastoparanos apresentam carga liquida de +1 a +4, devido à presença de resíduos ácidos e básicos, foram extraídos do veneno de vespas, três dos quais de espécie nativa da bodiversidade nacional, mostraram intensa atividade antimicrobiana. Nos peptídeos com Q = +1 e +2 predomina o caráter hidrofóbico enquanto nos demais o caráter hidrofílico; o peptídeo com Q = +4 tem sua estrutura resolvida por NMR e devido à alta homologia entre essa seqüência e dos demais se supõe que eles também sejam anfipáticos. A atividade lítica é caracterizada por uma razão [P]/[L] crítica entre as concentrações totais de peptídeo e lipídeo, acima da qual ocorre um processo cooperativo de liberação de corante do interior das vesículas. A razão crítica, a eficiência do vazamento e a cooperatividade mostraram ser dependentes na densidade superficial de carga da vesícula e da carga liquida do peptídeo. Observaram-se razões [P]/[L] críticas da ordem de sub-micromolar tanto em vesícula zwitteriônica quanto em vesícula aniônica. As curvas dose-resposta tornaram-se menos cooperativas com o aumento da carga líquida dos peptídeos, mostrando que a razão crítica aumenta com a carga. Os espectros... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Bioactive peptides are of high interest as substitutes of conventional antibiotics since some of them present antimicrobial action. They are predominantly cationic and it has been shown that their antimicrobial activity is modulated by electrostatic interactions, hydrophobic contributions and the elastic features of the membranes they target. In this work we analyzed the importance of charge and hidrofobicity to the interaction of four peptides with anionic and zwitterionic model membranes using electrokinetics potential, circular dicrohism and fluorescence spectrsocopy. These peptides named mastoparans, have exhibit a net charge ranging from +1 to +4 due to the presence of acidic and basic residues, and three of them, extracted from the venom of wasps native of the brazilian biodiversity showed intense antibacterial activity. The peptides with Q= +1 and +2, are hydrophobic and the other two are hydrophilic. Lytic activity of peptides, accessed by the release of fluorescent dye entrapped in lipid vesicles, showed sigmoid dose-response curves either in zwitterionic or in anionic vesicles with sub-micromolar threshold ratios. The lytic activity was characterized by a threshold [P]/[L] value, above which cooperative dye release takes place. The threshold ratio, the leakage efficiency and cooperativity were found to be dependent on the vesicle surface charge density and on the peptide net charge. Roughly the threshold ratios increase with the peptide net charge and as the net charge increases the dose response curves become less cooperative. Circular dichroism spectra of the peptides in vesicles exhibit two negative dichroic bands at 222 and 208 nm characteristic of helical structure, while they were observed to be random coil in buffer. At peptide and lipid concentrations near the threshold ratio the CD spectra have the... (Complete abstract click electronic access below) / Orientador: João Ruggiero Neto / Coorientador: Márcia Perez dos Santos Cabrera / Banca: Antônio José da Costa Filho / Banca: Karin do Amaral Riske / Mestre

Probabilistic machine learning and circular statistics—the branch of statistics concerned with data as angles and directions—are two research communities that have grown mostly in isolation from one another. On the one hand, probabilistic machine learning community has developed powerful frameworks for problems whose data lives on Euclidean spaces, such as Gaussian Processes, but have generally neglected other topologies studied by circular statistics. On the other hand, the approximate inference frameworks from probabilistic machine learning have only recently started to the circular statistics landscape. This thesis intends to redress the gap between these two fields by contributing to both fields with models and approximate inference algorithms. In particular, we introduce the multivariate Generalised von Mises distribution (mGvM), which allows the use of kernels in circular statistics akin to Gaussian Processes, and an augmented representation. These models account for a vast number of applications comprising both latent variable modelling and regression of circular data. Then, we propose methods to conduct approximate inference on these models. In particular, we investigate the use of Variational Inference, Expectation Propagation and Markov chain Monte Carlo methods. The variational inference route taken was a mean field approach to efficiently leverage the mGvM tractable conditionals and create a baseline for comparison with other methods. Then, an Expectation Propagation approach is presented drawing on the Expectation Consistent Framework for Ising models and connecting the approximations used to the augmented model presented. In the final MCMC chapter, efficient Gibbs and Hamiltonian Monte Carlo samplers are derived for the mGvM and the augmented model.

This thesis provides a case study on how the wind direction plays an important role in the amount of rainfall, in the village of Somi$acute{o}$. The primary goal is to illustrate how a meta-analysis, together with circular data analytic methods, helps in analyzing certain environmental issues. The existing GLS meta-analysis combines the merits of usual meta-analysis that yields a better precision and also accounts for covariance among coefficients. But, it is quite limited since information about the covariance among coefficients is not utilized. Hence, in my proposed meta-analysis, I take the correlations between adjacent studies into account when employing the GLS meta-analysis. Besides, I also fit a time series linear-circular regression as a comparable model. By comparing the confidence intervals of parameter estimates, covariance matrix, AIC, BIC and p-values, I discuss an improvement on the GLS meta analysis model in its application to forecasting problem in Environmental study.

Zinc is the second most abundant transition metal in biological systems. This cation is required for the catalytic activity of hundreds of enzymes which mediate protein synthesis, DNA replication and cell division. Despite the central importance of zinc in cellular homeostasis, the mechanism of zinc uptake, compartmentalization and efflux is unknown. Recently, a family of proteins, called ZIP, has been shown to control zinc uptake. Mutations in one of the genes coding for these proteins (ZIP4) can lead to potentially life-threatening diseases like Acrodermatitis Enteropathica and high levels of ZIP4 have been detected in patients suffering from pancreatic cancer. Therefore our goal is to investigate the mechanism of ZIP4 transport and regulation. It was previously shown that the intracellular loop between transmembrane III and IV (M3M4) of ZIP4 is ubiquitinated in the presence of high intracellular zinc which lead to protein degradation. Our initial hypothesis was that the large intracellular domain of ZIP4 (M3M4) is a sensor which detects the intracellular concentration of zinc and regulates the surface expression of ZIP4. In order to test this hypothesis we expressed and purified the M3M4 domain to examine the ability of M3M4 to bind zinc. Our results have demonstrated that M3M4 binds zinc with a 2:1 zinc:protein stoichiometry with nanomolar affinity. We have also shown that upon binding of zinc, M3M4 undergoes a large conformational change.

The challenge of tackling global climate change and our increasing reliance on power means that new and diverse renewable energy generation technologies are a necessity for the future. From a number of technologies reviewed at the outset, the cross-flow tidal turbine was chosen as the focus of the research. The numerical investigation begins by choosing to model flow around a circular cylinder as a challenging benchmarking and evaluation case to compare two potential solvers for the ongoing research, ANSYS CFX and OpenFOAM. A number of meshing strategies and solver limitations are extracted, forming a detailed guide on the topic of cylinder lift, drag and Strouhal frequency prediction in its own right. An introduction to cross-flow turbines follows, setting out turbine performance coefficients and a strategy to develop a robust numerical modelling environment with which to capture and evaluate hydrodynamic phenomena. The validation of a numerical model is undertaken by comparison with an experimentally tested lab scale turbine. The resultant numerical model is used to explore turbine performance with varying Reynolds number, concluding with a recommended minimum value for development purposes of Re = 350 × 103 to avoid scalability errors. Based on this limit a large scale numerical simulation of the turbine isconducted and evaluated in detail, in particular, a local flow sampling method is proposed and presented. The method captures flow conditions ahead of the turbine blade at all positions of motion allowing local velocities and angles of attack to be interrogated. The sampled flow conditions are used in the final chapter to construct a novel blade pitching strategy. The result is a highly effective optimisation method which increases peak turbine power coefficient by 20% for only two further case iterations of the numerical solution.

The work presented in this thesis deals with the structural and functional properties of peptides at surfaces. The interaction of peptides with surfaces is an ever so common occurrence in our every day life, from the bug squashed on the windshield of our car to the barnacle on our boat, and from the blood plasma used in the hospital to the proteins in our cells. The effect these occurrences has on our lives is diverse, the bug is annoying whereas the barnacle settlement of ship hull is costly for marine transportation, the blood plasma contains components of vital importance for our immunological defense system and the proteins in our cells are crucial for regulatory processes and life.One part of this thesis, performed as a part of the EU-founded project AMBIO, deals with the concept of marine biofouling. A number of short peptides have been designed, synthesized, and used to investigate their effect on the settlement on marine biofoulers, such as the Ulva linza algae and the Navicula diatom, on template surfaces coated with thin layers of these molecules. The surfaces have been thoroughly investigated with respect of their physio-chemical properties before and after submersion in artificial seawater and ultimately in suspensions containing the organisms. The most interesting results were obtained with an arginine-rich peptide coating that when introduced to Ulva linza zoospores, displayed extensive settlement, compared to reference surfaces. In addition, a large fraction of the settled spores had an abnormal morphology.The other part of this thesis is focused on designed peptides that when adsorbed on a negatively charged surface adopts a well-defined secondary structure, either α-helical or β-sheet. Precisely placed amino acids in the peptides will strongly disfavor structure in solution, primarily due to electrostatic repulsion, but when the peptides are adsorbed on the negatively charged surfaces, they adopt a well-defined secondary structure due to ion pair bonding. These interactions have been thoroughly investigated by systematic variations of the side-chains. In order to determine the factors contributing to the induced structure, several peptides with different amino acid sequences have been synthesized. Factors that have been investigated include 1) the positive charge density, 2) distribution of positive charges, 3) negative charge density, 4) increasing hydrophobicity, and 5) incorporating amino acids with different helix propensities. Moreover, pH dependence and the effect of different interaction partners have also been investigated. It has also been shown that the system can be modified to incorporate a catalytic site that is only active when the helix is formed. This research will increase our understanding of peptide-surface interactions and might be of importance for both bionanotechnology and medicine.

Nos últimos anos a discussão acerca da autonomia da política monetária esteve polarizada entre dois grupos de autores. Baseados numa concepção arqueológica da moeda (Cencini, 1997), alguns afirmam que os Bancos Centrais, diante da integração entre os mercados financeiros, teriam perdido a autonomia para praticar políticas monetárias em favor do crescimento econômico. Em contraste, outro grupo de autores sustenta que mesmo no atual contexto de “perfeita mobilidade do capital”, sob certas condições, a autoridade monetária conserva amplos graus de liberdade para definir o nível da taxa de juros doméstica, em qualquer contexto considerado. O objetivo principal do estudo é analisar teoricamente a questão da autonomia da política monetária nos termos em que a mesma vem sendo discutida na atualidade, e subseqüentemente, através de um modelo macroeconômico de simulação, examinar as conseqüências de uma política de juros alternativa àquela que o Banco Central do Brasil vem adotando. Constatou-se que em uma economia de mercado, em que muitos insumos produtivos são reproduzíveis, incluindo a força de trabalho e os bens de capital, emerge uma relação definida entre a dimensão do consumo produtivo da força de trabalho, visando a preservação das condições materiais da economia, e a magnitude dos meios de pagamento existentes: os meios de pagamento podem ser criados e destruídos no sistema bancário por causa do pagamento de salários aos trabalhadores, sob demanda das empresas. Sob essa ótica há certa dificuldade analítica para se conceber os meios de pagamento exogenamente determinados. Ao contrário, o caráter institucional, discricionário da taxa monetária de juros segue simples e logicamente. O mercado financeiro atua no sentido de restaurar a liquidez das empresas de negócios facilitando a liquidação de seus empréstimos passados junto aos bancos comerciais. Através da aplicação de um modelo macroeconômico de simulação dois cenários alternativos foram gerados para os próximos oito anos de política (2008-2015). No cenário de mudança uma política de redução progressiva da taxa de juros para o patamar de 3,66% ao ano resulta em uma taxa de inflação muito similar ao cenário de continuidade, caracterizado por uma taxa de juros de 15,39% ao ano. Porém, no primeiro caso ocorre um aumento substancial no crescimento da capacidade produtiva da economia com uma taxa cambial mais competitiva, que estaria situada, em média, em R$/US$ 2,51. Por outro lado, no cenário de continuidade a perda anual, em média, no acréscimo da capacidade produtiva da economia é de 7,44%, associada a uma taxa cambial não competitiva, que em média estaria situada em R$/US$ 2,35. A estabilidade de preços foi preservada em todos os cenários. / In recent years several authors have questioned the power of monetary authority to fix domestic money rate of interest at lower levels of their neighbors. The main reason would be the increasing financial integration of markets, and their “capital flows”. The “Flow Theory” (Branson, 1970) asserts that in a world where capital is perfectly mobile the power of Central Bank would be reduced at minimal levels, because of the exogenous character of money. So, active monetary policies to attain and maintain full employment would be not possible in that world, as a low and still positive interest rate. The aim of this study is to evaluate theoretical and empirically this claim for a market economy, considering the case of Brazilian economy. The main theoretical conclusion does not confirm that claim. On the contrary, in a market economy where several inputs are reproducible, including labor force and capital equipment, a definite relation comes about between the length of productive consumption, to guarantee material conditions of the economy, and means of payment: immaterial means of payment can be created and destroyed by banks because of wages, on demand of enterprises in money market. In this way there are some analytical difficulties to conceive money as a stock of wealth, as a material and exogenous object. Yet, the institutional and conventional character of money rate of interest, in any context, follows simple and direct because of the social and circular nature of production. The power of monetary authority is reinforced this way. By applying a macroeconomic simulation model designed to Brazilian economy to investigate the effect of an interest rate at an international level over the accumulation rate, inflation and exchange rate, alternative scenarios were obtained to the next eight years of policy (2008-2015). The main results suggest that if Central Bank would decide to fix the money rate of interest at 3,66% per year, the accumulation rate would be substantially greater and the exchange rate would stabilize around R$/US$ 2,51. But, if the monetary authority chooses to fix politically a higher rate, say 15,39% per year, the accumulation rate would be substantially lower and the exchange rate would be around R$/US$ 2,35 for the next eight years. The stable prices were maintained in all scenarios. There is no trade-off between growth and stability. So, the best choice of monetary authority would be a low but still positive money rate of interest to permit a greater production level and competitiveness at international arena.