Nesta tese são desenvolvidos três estudos sobre as reservas internacionais brasileiras, utilizando diferentes técnicas econométricas, com o objetivo de determinar a influência de medidas absolutas e relativas de reservas sobre o rating soberano de crédito e o spread soberano, bem como o nível adequado para garantir a liquidez externa. As análises foram feitas com dados mensais do período jan/2000-jun/2008. No primeiro estudo, mostrou-se que diferentes medidas de reservas internacionais apresentam efeito significativo na explicação do rating soberano de crédito, através de modelos ordered logit para a média dos ratings emitidos pelas três principais agências (Moody's, Standard & Poors e Fitch). Entretanto, o indicador de maior poder explicativo não foi o nível absoluto de reservas, mas a razão entre dívida pública externa líquida e PIB. Outras variáveis de destacada importância na maioria dos modelos foram o percentual da dívida interna de curto prazo, investimento estrangeiro direto/PIB e inflação. Variáveis tradicionalmente utilizadas como indicadores de liquidez, como razão reservas/importações e conta corrente/PIB, não foram significativas na maioria dos modelos. Os resultados confirmam os indícios contidos no discurso das agências de rating, quanto à importância das reservas internacionais em sua avaliação, embora alertando que outras variáveis, como perfil de endividamento do governo e perspectivas de crescimento, são também fundamentais. O segundo estudo de caso encontrou relação significativa entre as reservas internacionais e o spread soberano, através de modelos de correção de erros. O efeito estimado do rating soberano foi não-significativo ou pouco explicativo, comparado aos fundamentos, provavelmente devido à volatilidade do spread soberano em resposta a variações nas condições do mercado, ao contrário do rating. O melhor modelo obtido utilizou o nível absoluto de reservas, evidenciando também efeitos significativos da aversão global ao risco, taxas de juros internacionais e crises políticas internas. Os resultados desse estudo indicam custo marginal decrescente das reservas internacionais e a necessidade de considerá-lo endógeno em modelos de minimização de custos para determinação do nível ótimo de reservas. O terceiro estudo implementou a metodologia de Liquidity-at-Risk sugerida por Greenspan (1999) para avaliar a adequação do nível de reservas internacionais para a manutenção da liquidez externa. Para a medida de liquidez reservas/dívida externa de curto prazo (razão de Guidotti), estimou-se que o nível de reservas internacionais mantidas pelo Brasil em jun/2008 (US$200 bilhões) era aproximadamente o dobro do necessário para garantir uma razão de Guidotti superior a 1, com 99% de probabilidade, durante 24, 36 ou 48 meses. Em diversos cenários alternativos de percentual das dívidas externa e interna de curto prazo, meta de superávit primário, índice de aversão ao risco e taxas de juros externas, as reservas iniciais necessárias situaram-se em US$85-105 bilhões. A análise de custos revela que o aumento das reservas diminui os juros médios da dívida, embora efeito maior pudesse ser alcançado através do aumento do superávit primário. As evidências sugerem que a motivação das autoridades brasileiras para a manutenção de reservas em torno de US$200 bilhões não é puramente precaucionária, admitindo as hipóteses de ganho de credibilidade e flexibilidade para a execução da política fiscal. / This thesis developed three case studies on the Brazilian international reserves, using various econometric techniques in order to determine the influence of absolute and relative measures of reserves over both the sovereign credit rating and the sovereign spread, as well as to assess the adequate reserves level to ensure external liquidity. Analyses were carried out on monthly data from Jan/2000 to Jun/2008. The first case study found significant effects of different reserves measures in explaining the sovereign credit rating, by fitting ordered logit models to the average of the ratings issued by the three main agencies (Moody's, Standard & Poors and Fitch) for the Brazilian long term external debt. However, the best explaining variable was not the absolute level of reserves, but the ratio "net public external debt/GDP" instead. It was noteworthy the significance of the following variables in most of the models tested: short term internal debt (%), foreign direct investment/GDP and inflation. Variables traditionally used as external liquidity measures, like reserves/imports and current account/GDP, are not statistically significant in most of the models fitted in this study. Results support the evidence found in the rating agencies' reports, as to the importance of international reserves in their credit quality assessment, although pointing to other variables, like government debt profile and growth perspectives, as equally critical. The second case study found significant relationship between the Brazilian international reserves and its sovereign spread, using error correction models. The estimated effect of sovereign rating was either non-significant, or poorly explanatory when compared to macroeconomic fundamentals, probably due to the volatility of sovereign spread in response to changes in market conditions, unlike the sovereign rating. The best model obtained included the absolute level of reserves, showing also significant effect of the global risk aversion, external interest rates and internal political crises. The results of this study point to a decreasing marginal cost of international reserves and the need of considering it as endogenous in optimal reserves models based in cost minimization. Finally, the third case study implemented the Liquidity-at-Risk methodology suggested by Greenspan (1999), in order to assess the Brazilian reserves level adequacy in maintaining external liquidity. For the liquidity measure adopted - the ratio "reserves/short term external debt" (Guidotti's ratio) - it was found that the Brazilian reserves level held in Jun/2008 (US$200 billion) was roughly twice the necessary one to ensure a Guidotti's ratio above 1, with 99% probability, within 24, 36 or 48 months. In several alternative scenarios varying the short term external debt, short term internal debt, primary surplus, global risk aversion and external interest rates, the required initial reserves was in the range US$85-105 billion. An analysis of alternative policies' costs revealed the expected effect of higher reserves in decreasing the average debt service, although a dramatically higher impact would be obtained by an increase in primary surplus. Evidence suggest that the Brazilian authorities motivation for holding international reserves as high as US$200 billion may not be purely precautionary, pointing to the hypotheses of credibility gains and fiscal flexibility issues.

Dans cette thèse, nous étudions dans une première partie l'impact de la contrainte de sécurité en tatouage. Dans le contexte WOA (Watermarked contents Only Attack), un adversaire possède plusieurs contenus tatoués et cherche à estimer la clé secrète d'insertion afin d'accéder aux messages cachés. Une nouvelle manière de tatouer en étalement de spectre est présentée ici. Celle-ci est basée sur la construction de distributions circulaires dans le sous-espace secret de tatouage. Cette technique permet de minimiser la distorsion en moyenne provoquée par l'ajout de la marque dans le contexte WOA en utilisant l'algorithme d'optimisation des Hongrois et la théorie du transport. Nous vérifions ensuite qu'un tatouage sûr est utilisable en pratique en prenant comme exemple le tatouage d'images naturelles. Dans une seconde partie, nous nous intéressons au cadre de l'estampillage d'oe uvres numériques permettant de tracer les redistributeurs de copies illégales. Les codes traçants utilisés sont ceux proposés par Gabor Tardos et sont résistants aux attaques de coalition, c'est-à-dire au groupement d'adversaires mettant en commun leurs contenus numériques afin de forger une version pirate. Puisque les techniques de tatouage permettent l'insertion de codes traçants dans un contenu numérique, nous avons conçu une attaque "au pire cas" qui dépend du niveau de sécurité et qui permet, pour les adversaires, de baisser leur accusation. Nous montrons que pour le cas particulier de l'estampillage un tatouage sûr sera plus efficace qu'un tatouage non-sûr (à robustesse équivalente). Finalement, une implantation des codes traçants dans un contenu vidéo utilisant des méthodes sûres par étalement de spectre est proposée. Nous montrons alors l'efficacité de l'accusation des adversaires dans ce cadre pratique. / In this thesis, we first study the constraint of security in watermarking. In the WOA (Watermarked contents Only Attack) framework, an adversary owns several marked contents and try to estimate the secret key used for embedding in order to have access to the hidden messages. We present a new mean for spread-spectrum watermarking based on circular distributions in the private watermarking subspace. Thanks to this technique, we are able to minimise the distortion (on expectation) caused by the watermark in the WOA framework using the Hungarian optimisation method and the transportation theory. Then, we show that secure watermarking can be used in practical works with the example of still image watermarking. In the second part, we are interested about the problem of active fingerprinting which allows to trace re-distributors of illegal copies of a numerical content. The codes we use here are the ones proposed by Gabor Tardos. These codes are resistant against collusion attacks e.g. a group of malicious users who forges a new content by mixing their copies. Since watermarking techniques allow the embedding of these codes in numerical contents, a new worst case attack taking into account the security level of the watermarking system is proposed to reduce the accusation rate of the coalition. We show that secure watermarking is more efficient that insecure one (with similar robustness) for fingerprinting application. Finally, traitor tracing codes are implemented on video sequences by using spread-spectrum techniques in order to demonstrate that the accusation of adversaries is practically possible.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-05-10T15:32:35Z No. of bitstreams: 1 EMANOELA PEREIRA DE PAIVA - DISSERTAÇÃO PPGHT 2014..pdf: 1247989 bytes, checksum: 71e09e36ef957366d878001bfc7fb6d7 (MD5) / Made available in DSpace on 2018-05-10T15:32:35Z (GMT). No. of bitstreams: 1 EMANOELA PEREIRA DE PAIVA - DISSERTAÇÃO PPGHT 2014..pdf: 1247989 bytes, checksum: 71e09e36ef957366d878001bfc7fb6d7 (MD5) Previous issue date: 2014-02-17 / Objetivou-se neste trabalho avaliar diferentes técnicas de propagação vegetativa da romãzeira. No primeiro momento, objetivou-se testar técnicas de estaquia, com o intuito de avaliar a viabilidade de propagação das variedades ‘Molar’ e ‘Wonderful’ na estação de seca e chuvosa. Posteriormente, verificou-se a viabilidade de produção de mudas enxertadas com estas duas variedades, utilizando-se como porta-enxerto mudas da variedade ‘Molar’ propagadas por estaquia. A pesquisa foi realizada de agosto de 2012 a novembro de 2013, em casa de vegetação, no campus do Centro de Ciências e Tecnologia Agroalimentar da Universidade Federal de Campina Grande, Pombal/PB. Objetivando estudar a propagação por estaquia da romãzeira, foram realizados dois experimentos com cada variedade (‘Molar’ e ‘Wonderful’), um no período seco, que compreendeu de agosto a dezembro de 2012 (Experimento I), e outro no período chuvoso, de janeiro a junho de 2013 (Experimento II), para as duas variedades. Utilizou-se o delineamento inteiramente casualizado, com quatro repetições e cinco mudas por repetição, adotando-se o esquema fatorial composto por dois fatores, o manejos de estacas (Estacas com folhas; Estacas sem folhas e Estacas sem folhas mais incisão na base) e épocas de avaliação (dias após o plantio das estacas), de modo a estudar o crescimento, fisiologia e acúmulo de massa seca das mudas de romãzeira. Com o intuito de estudar a propagação por enxertia, utilizou-se o delineamento inteiramente casualizado, considerando-se o esquema fatorial (4 x 4), quatro métodos de enxertia (Garfagem no topo em fenda cheia; Garfagem em fenda lateral; Borbulhia em placa e Borbulhia em T invertido) x quatro épocas de avaliação (45; 60; 75 e 90 dias após a enxertia), com quatro repetições e cinco mudas por unidade experimental, de modo a avaliar o crescimento, fisiologia e acúmulo de massa seca das mudas de romãzeira. As estacas manejadas com incisão na base proporcionaram o maior crescimento e vigor das mudas de ambas as variedades de romãzeira estudadas, e a época chuvosa do ano favorece a propagação vegetativa da romãzeira. Os métodos de enxertia por garfagem proporcionaram melhor desenvolvimento das mudas de romãzeira, sendo as mudas enxertadas por garfagem em fenda lateral as que obtiveram maior crescimento e acúmulo de matéria seca. / The objective of this study was to evaluate different techniques for the vegetative propagation of the pomegranate. In the first moment, our objective was to test techniques for cutting, in order to assess the feasibility propagation varieties 'Molar' and 'Wonderful' in the dry and rainy seasons. Subsequently, we verified the feasibility of production of grafted seedlings with these two varieties, using as rootstock seedlings of the variety 'Molar' propagated by cuttings. The survey was conducted from August 2012 to November 2013, in a greenhouse, in the Campus Center of Science and Agrifood Technology, Federal University of Campina Grande, Pombal-PB, Brazil. Aiming to study the propagation by cuttings of pomegranate, two experiments were conducted with each variety ('Molar' and 'Wonderful'), one in the dry season, which comprised August to December 2012 (Experiment I) and another in the rainy season, from January to June 2013 (Experiment II), for the two varieties. We used a completely randomized design with four replications and five plants per replication, adopting the factorial design consisting of two factors, the managements of cuttings (cuttings with leaves, cuttings without leaves and cuttings without leaves more incision at the base) and evaluation periods (days after planting the cuttings) in order to study the growth, physiology and dry mass of seedlings pomegranate. In order to study the propagation by grafting, we used the randomized design, considering the factorial (4 x 4), four methods of grafting (grafting the top cleft, cleft in lateral slit; budding plate and T budding inverted) x four times of assessment (45, 60, 75 and 90 days after grafting), with four replications and five plants per experimental unit in order to evaluate the growth, physiology and accumulated dry weight of seedlings pomegranate. Cuttings managed with incision at the base gave a higher growth and strength the seedlings of both varieties studied pomegranate and the rainy season favors the vegetative propagation of the pomegranate. The methods of grafting provided better growth of seedlings of pomegranate. Being the grafted seedlings by grafting the left side with the greatest growth and dry matter accumulation.

Ces travaux de thèse ont porté sur le développement d’un modèle de propagation d’un incendie de forêt et son intégration dans une chaîne opérationnelle d'aide à la lutte tactique. C'est un modèle dont la propagation s'effectue sur un réseau de sites combustibles qui prend en compte les mécanismes principaux de transfert de chaleur radiatifs et convectifs des sites en feu vers les sites sains et l'environnement. Ce modèle tient également compte du relief et des conditions locales de vent et végétation. La simulation « temps réel » a nécessité deux développements distincts. Le premier a consisté à combiner la méthode de Monte Carlo à un algorithme génétique pour créer une base de données des facteurs de vue radiatifs de la flamme sur la végétation environnante, pour une large gamme de propriétés de flammes et de conditions environnementales. Le second repose sur une méthode de suivi du front de feu afin de limiter les données manipulées aux seules données utiles au calcul de sa propagation. La phase de validation a porté sur l’analyse comparative des contours de feux calculés par le modèle avec ceux mesurés lors de deux brûlages dirigés, dont un réalisé en Thaïlande dans le cadre de cette thèse, et ceux mesurés lors du feu de Favone de 2009 en Corse et d'un feu de grande ampleur aux États-Unis. Les temps de calcul sont très inférieurs au temps réel. Le modèle a été ensuite étendu pour permettre une évaluation du risque incendie à l’interface forêt-habitat. Dans le cadre du projet TechForFire, porté par la société NOVELTIS, il a été enfin couplé aux différents modules de la chaîne opérationnelle. La chaîne complète a été validée sur le feu historique de Velaux de 2015. / This thesis work is focused on the development of a wildfire spread model and its integration into a decision-making tool for planning firefighting operations. The fire spread model is based on a network model to represent vegetation distribution on land and considers the main heat transfer mechanisms from burning to unburnt vegetation items (i.e. radiation from the flaming zone and embers, surface convection and wind-driven convection through the fuel bed, and radiative cooling from the heated fuel element to the environment). The effects of local conditions of wind, topography, and vegetation are included. To address the challenge of real-time fire spread simulations, the model is also extended in two ways. First, the Monte Carlo method is used in conjunction with a genetic algorithm to create a database of radiation view factors from the flame to the fuel surface for a wide variety of flame properties and environment conditions. Second, the front-tracking method is introduced in order to reduce the amount of data to store and handle during propagation. The fire spread model is validated against data from different fire scenarios, showing it is capable of capturing the trends observed in experiments in terms of rate of spread, and area and shape of the burn, with reduced computational resources. It is then extended to evaluate fire risk at the wildland fire interface. In the frame of the TechForFire project coordinated by the NOVELTIS company, the new version of the fire spread model is coupled with the other modules of the operational chain. Finally, data from the fire of Velaux in 2015 are used to evaluate the TechForFire solution.

In the past two decades, Fluorescence microscopy has imparted tremendous impact in Biology and Imaging. Several super-resolution Fluorescence imaging techniques (e.g. PALM, STED, STORM, 4Pi and structured illumination) have enabled diff raction-unlimited imaging. But high resolution is limited to a depth of few tens of microns. Thus, deep tissue imaging and simultaneous volume imaging have become a highly sought after feature in Fluorescence microscopy. The research work in this thesis address these issues by using spatial filtering techniques to tailor the point spread function (PSF) which uniquely characterizes the optical sys-tem. The advantage of this approach lies in the fact that intricate details about the focal region can be computed and designed with the help of well established theory and experimentation. In particular, this technique was applied to both spherical and cylindrical lenses. The former was used to generate Bessel-like, non-diffracting beams which demonstrated the ability to penetrate deep inside tissue-like media and thereby yielded an imaging depth of nearly 650μm as compared to about 200μm for a state-of-the-art confocal microscope. The latter gave rise to light-sheet and it's extended version that is ideal for planar imaging at large penetration depths. Another development is the generation of multiple light-sheet illumination pattern that can simultaneously illuminate several planes of the specimen. The proposed multiple light-sheet illumination microscopy (MLSIM) technique may enable volume imaging in Fluorescence microscopy. The first two chapters of this thesis are introductory in nature and provides a general overview of the principles of Fluorescence microscopy and three state-of-the-art Fluorescence imaging techniques; namely confocal, multi-photon and light-sheet based microscopy. Confocal microscopes are widely considered as a standard tool for biologists and this discussion shows that even though they have made signi ficant contributions in the fields of biophysics, biophotonics and nanoscale imaging, their inability to achieve better penetration depth has prevented their use in thick, scattering samples such as biological tissue. The system PSF of a confocal microscope broadens as it goes deeper in-side a scattering sample resulting in poor-resolution thereby destroying the very concept of high resolution, noise-free imaging. Additionally, confocal microscopy suffers from in-creased photo-bleaching due to o -layer (above and below the focal plane) excitation and low temporal resolution since it requires point-by-point scanning mechanism. On the other hand, multi-photon microscopy offers several advantages over confocal microscopy such as reduced photo-bleaching and inherent optical sectioning ability, however, it still lacks in providing high temporal resolution. Light-sheet based microscopy have gained popularity in recent years and promises to deliver high spatio-temporal resolution with minimized photo-bleaching. Recently, a considerable amount of research has been dedicated to further develop this promising technique for a variety of applications. The ability to look deeper inside a biological specimen has profound implications. How-ever, at depths of hundreds of microns, several effects (such as scattering, PSF distortion and noise) deteriorates the image quality and prohibits detailed study of key biological phenomenon. Chapter 3 of this thesis describes the original research work which experimentally addresses to this issue. Here, Bessel-like beam is employed in conjugation with an orthogonal detection scheme to achieve imaging at large penetration depth. Bessel beams are penetrative, non-di ffracting and have self-reconstruction properties making them a natural choice for imaging scattering prone specimens which are otherwise inaccessible by other microscopy imaging techniques such as, Widefield, CLSM, 4PI, Structural illumination microscopy and others. In this case such a Bessel-like beam is generated by masking the back-aperture of the excitation objective with a ring-like spatial filter. The proposed excitation scheme allow continuous scanning by simply translating the detection optics. Additionally, only a pencil-like region of the specimen can be illuminated at a given instance thereby reducing premature photobleaching of neighboring regions. This illumination scheme coupled with orthogonal detection shows the ability of selective imaging from a desired plane deep inside the specimen. In such a configuration, the lateral resolution of the illumination arm determines the axial resolution of the overall imaging system. Such an imaging system is a boon for obtaining depth information from any desired specimen layer that includes nano-particle tracking in thick tissue. Experiments performed by imaging the Fluorescent polymer tagged-CaCO3 particles and yeast cell in a tissue-like gel-matrix demonstrates penetration depth that extends up to 650 m. This will advance the field of fluorescence imaging microscopy and imaging. Similar to the ability to observe deep inside a sample, simultaneous 3D monitoring of whole specimens play a vital role in understanding many developmental process in Biology. At present, light-sheet based microscopy is the prime candidate amongst the various microscopy techniques, that is capable of providing high signal-to-background-ratio as far as planar imaging is concerned. Since spatial filtering technique was found to successfully give rise to novel features (such as large penetration depth) in a fluorescence microscope setup, a logical extension would be to implement a similar approach with a light-sheet based microscope setup. These implementations are discussed in Chapter 4 of this thesis where spatial filtering is employed with cylindrical lenses. For facilitating computational and experimental studies, a vectorial formalism was derived to give an explicit computable integral solution of the electric field generated at the focal region of a cylindrical lens. This representation is based on vectorial diffraction theory and further enables the computation of the point spread function of a cylindrical lens. Commonly used assumptions are made in the derivation such as no back-scattering and negligible contribution from evanescent fields. Stationary phase approximation along with the Fresnel transmission coefficients are employed for evaluating the polarization dependent electric field components. Computational studies were carried out to determine the polarization effects and calculate the system resolution. Experimental comparison of light-sheet intensity pro les show good agreement with the theoretical calculations and hence validate the model. This formalism was derived as a first step since it gives the essential understanding of tightly focused E-fields of a high N.A. cylindrical lens systems and thereby helps in further understanding the effect of spatial filtering. As the next step, generation of extended light-sheet for fluorescence microscopy is pro-posed by introducing a specially designed double-window spatial filter at the back-aperture of a cylindrical lens. The filter allows the light to pass through the periphery and center of a cylindrical lens. When illuminated with a plane wave, the proposed filter results in an extended depth-of-focus along with side-lobes which are due to other interferences in the transverse focal plane. Computational studies show a maximum extension of light-sheet by 3:38 times for single photon excitation, and 3:68 times for multi-photon excitation as compared to state-of-art single plane illumination microscopy (SPIM) system and essentially implies a larger field of view. Finally, generation of multiple light-sheet pattern is proposed and demonstrated using a different spatial filter placed at the back aperture of a cylindrical lens. A complete imaging setup consisting of multiple light-sheets for illumination and an orthogonal detection arm, is implemented for volume imaging in fluorescence microscopy. This proposed scheme is a single shot technique that enables whole volume imaging by simultaneously exciting multiple specimen layers. Experimental results confirm the generation of multiple light-sheets of thickness 6:6 m with an inter-sheet spacing of 13:4 m. Imaging of 3 5 m sized fluorescently coated Yeast cells (encaged in Agarose gel-matrix) is per-formed and conclusively demonstrates the usefulness and potential of multiple light-sheet illumination microscopy (MLSIM) for volume imaging. As part of the future scope of the research work presented in this thesis, the Bessel-beam based improved depth microscopy technique may attract applications in particle tracking deep inside tissues and optical injection apart from fluorescence imaging applications. The vectorial formalism derived for cylindrical lens can be used to predict other, complex optical setups involving cylindrical lenses. Extended light-sheet generation proposed in this work by using appropriate spatial filtering with a cylindrical lens, complements the existing and popular selective plane illumination microscopy technique and may facilitate the study of large biological specimens (such as, full-grown Zebra sh and tissue) with high spatial resolution and reduced photobleaching. Finally, the MLSIM technique presented in this thesis may accelerate the field of developmental biology, cell biology, fluorescence imaging and 3D optical data storage.

Esta tese propõe um método de avaliação de sistemas de obtenção de imagem radiológica através das Funções de Transferência simuladas para qualquer região do campo de radiação. Esse processo de simulação reflete as mudanças sofridas pelo ponto focal e, portanto, pela Função de Espalhamento de Ponto (FEP) ao longo do campo. A avaliação utiliza informações obtidas de Funções de Transferência ótica bi-dimensionais calculadas através da aplicação de Transformadas de Fourier sobre as Funções de Espalhamento de Ponto simuladas. O método permite realizar um mapeamento da resposta em freqüências espaciais dos sistemas radio1ógicos para todo o campo de radiação, comparar a nitidez da imagem de sistemas distintos com relação a regiões equivalentes e estudar uma região especifica para prever as distorções que serão inseridas na imagem. / In this work a method of evaluation for the radiological imaging systems performance by simulated transfer functions for any X-ray field region is proposed. The simulation procedures provide information of the changes of the focal spot sizes and, therefore, of the Point Spread Function (PSF) along the field. The evaluation yields the bi-dimensional optical Transfer Functions calculated from Fourier Transformation of the simulated PSFs. This method provides: the spatial frequency response for the entire radiation field of the radiological systems; comparisons of the image sharpness relative to equivalent field regions for different systems; and the study of a singular region in order to predict image distortions.

O presente trabalho teve por objetivo registrar os diálogos entre os diferentes campos de conhecimentos, que serviram de postulado para orientar as ações do projeto de pesquisa e extensão, Avaliação Técnica, Econômica e Socioambiental da Atividade Artesanal no Quilombo de Ivaporunduva, Vale do Ribeira (SP), bem como aportar as possíveis contribuições deste Projeto para estreitar o diálogo entre o conhecimento científico e os saberes originários das experiências e das práticas dos componentes do Grupo de Artesanato da comunidade de Ivaporunduva, localizada no município de Eldorado, Vale do Ribeira, estado de São Paulo, Brasil. Realizou-se análise de documentos produzidos pelo Projeto; foram feitas entrevistas com técnicos, professores e/ou pesquisadores e alunos, e com membros do Grupo de Artesanato; além disso, realizaram-se observações das ações do Projeto na academia e na comunidade. Verificouse que as atividades desenvolvidas no âmbito acadêmico contribuíram para construção gradual da prática inter e/ou transdisciplinar, na medida em que as ações do Projeto necessitaram reunir diferentes áreas do saber para resolver dificuldades técnicas encontradas para a consolidação da atividade. Observou-se ainda que há graus de comprometimento variados, entre os diferentes profissionais, de campos disciplinares distintos. Contudo, a abertura por parte do corpo discente vem sendo um veículo importante para a interlocução de saberes, que tem estimulado o exercício da prática inter e/ou transdisciplinar. Constatou-se que a Universidade, enquanto produtora e disseminadora de conhecimentos requer mudanças, no sentido de promover a aproximação dos campos disciplinares, tendo em vista a construção de um conhecimento integrado. Já no âmbito comunitário foi possível constatar que, as ações do Projeto contribuíram para aproximar os saberes técnico-científicos das experiências e das práticas do Grupo de Artesanato, visando a resolução de problemas de ordem técnica, de comercialização e de gestão que inviabilizam a consolidação da atividade artesanal naquela comunidade. Conclui-se, portanto, que a interlocução entre diferentes campos do conhecimento, bem como o diálogo entre o conhecimento científico e outros saberes pode contribuir para o debate epistemológico e, por conseguinte para construção de um conhecimento integrador. / The aim of this research work was to register the dialogues between the different knowledge fields, which served to direct the actions of the research and extension project, Technical, Economic, Social and Environmental evaluation of the Handicraft activities inside the Ivaporunduva Quilombo, Vale do Ribeira (SP), as well as to signed the possible contributions of this project to close the dialogue between scientific knowledge and knowledge came from the experience of the members of the Ivaporunduva community, located in El Dorado, Vale do Ribeira, São Paulo State, Brazil. The documents elaborated by the project were analyzed; as well as were made interviews with technicians, professors and/or researchers and students involved in the project, and with the members of the Handicraft Group. Besides, observations of the project actions inside the academy and the community were made. This analysis checked out the activities developed in the academic sphere that contributed to the grade construction of an inter-disciplinary and/or trans-disciplinary practice, since the project actions needed to bring together different knowledge areas to solve technical difficulties to allow the consolidation of the activity. Hence, this research work, noticed the varied grades of commitment existing among the different professionals from different subject fields. However, the open attitudes of the university students have been an important vehicle to the knowledges dialogue, what have been stimulating the inter-disciplinary and/or trans-disciplinary practice. There were realized that the university, as producer and spreader of knowledge, needs changes, to promote the approximation between subject fields, having in view the construction of an including knowledge. Inside the communitarian sphere was possible to realize that the project actions contributed to approximate the technical-scientific knowledge and the Handicraft Group activities, looking to solve technical, sale and management problems that produced difficulties to establish the craftwork activity with in the community. Therefore, this conclude that the dialogue between different knowledge fields as well as the dialogue between the scientific knowledge and other kinds of knowledge could contribute to the epistemic debate and, therefore, to the construction of an including knowledge.

Nesta tese são desenvolvidos três estudos sobre as reservas internacionais brasileiras, utilizando diferentes técnicas econométricas, com o objetivo de determinar a influência de medidas absolutas e relativas de reservas sobre o rating soberano de crédito e o spread soberano, bem como o nível adequado para garantir a liquidez externa. As análises foram feitas com dados mensais do período jan/2000-jun/2008. No primeiro estudo, mostrou-se que diferentes medidas de reservas internacionais apresentam efeito significativo na explicação do rating soberano de crédito, através de modelos ordered logit para a média dos ratings emitidos pelas três principais agências (Moody's, Standard & Poors e Fitch). Entretanto, o indicador de maior poder explicativo não foi o nível absoluto de reservas, mas a razão entre dívida pública externa líquida e PIB. Outras variáveis de destacada importância na maioria dos modelos foram o percentual da dívida interna de curto prazo, investimento estrangeiro direto/PIB e inflação. Variáveis tradicionalmente utilizadas como indicadores de liquidez, como razão reservas/importações e conta corrente/PIB, não foram significativas na maioria dos modelos. Os resultados confirmam os indícios contidos no discurso das agências de rating, quanto à importância das reservas internacionais em sua avaliação, embora alertando que outras variáveis, como perfil de endividamento do governo e perspectivas de crescimento, são também fundamentais. O segundo estudo de caso encontrou relação significativa entre as reservas internacionais e o spread soberano, através de modelos de correção de erros. O efeito estimado do rating soberano foi não-significativo ou pouco explicativo, comparado aos fundamentos, provavelmente devido à volatilidade do spread soberano em resposta a variações nas condições do mercado, ao contrário do rating. O melhor modelo obtido utilizou o nível absoluto de reservas, evidenciando também efeitos significativos da aversão global ao risco, taxas de juros internacionais e crises políticas internas. Os resultados desse estudo indicam custo marginal decrescente das reservas internacionais e a necessidade de considerá-lo endógeno em modelos de minimização de custos para determinação do nível ótimo de reservas. O terceiro estudo implementou a metodologia de Liquidity-at-Risk sugerida por Greenspan (1999) para avaliar a adequação do nível de reservas internacionais para a manutenção da liquidez externa. Para a medida de liquidez reservas/dívida externa de curto prazo (razão de Guidotti), estimou-se que o nível de reservas internacionais mantidas pelo Brasil em jun/2008 (US$200 bilhões) era aproximadamente o dobro do necessário para garantir uma razão de Guidotti superior a 1, com 99% de probabilidade, durante 24, 36 ou 48 meses. Em diversos cenários alternativos de percentual das dívidas externa e interna de curto prazo, meta de superávit primário, índice de aversão ao risco e taxas de juros externas, as reservas iniciais necessárias situaram-se em US$85-105 bilhões. A análise de custos revela que o aumento das reservas diminui os juros médios da dívida, embora efeito maior pudesse ser alcançado através do aumento do superávit primário. As evidências sugerem que a motivação das autoridades brasileiras para a manutenção de reservas em torno de US$200 bilhões não é puramente precaucionária, admitindo as hipóteses de ganho de credibilidade e flexibilidade para a execução da política fiscal. / This thesis developed three case studies on the Brazilian international reserves, using various econometric techniques in order to determine the influence of absolute and relative measures of reserves over both the sovereign credit rating and the sovereign spread, as well as to assess the adequate reserves level to ensure external liquidity. Analyses were carried out on monthly data from Jan/2000 to Jun/2008. The first case study found significant effects of different reserves measures in explaining the sovereign credit rating, by fitting ordered logit models to the average of the ratings issued by the three main agencies (Moody's, Standard & Poors and Fitch) for the Brazilian long term external debt. However, the best explaining variable was not the absolute level of reserves, but the ratio "net public external debt/GDP" instead. It was noteworthy the significance of the following variables in most of the models tested: short term internal debt (%), foreign direct investment/GDP and inflation. Variables traditionally used as external liquidity measures, like reserves/imports and current account/GDP, are not statistically significant in most of the models fitted in this study. Results support the evidence found in the rating agencies' reports, as to the importance of international reserves in their credit quality assessment, although pointing to other variables, like government debt profile and growth perspectives, as equally critical. The second case study found significant relationship between the Brazilian international reserves and its sovereign spread, using error correction models. The estimated effect of sovereign rating was either non-significant, or poorly explanatory when compared to macroeconomic fundamentals, probably due to the volatility of sovereign spread in response to changes in market conditions, unlike the sovereign rating. The best model obtained included the absolute level of reserves, showing also significant effect of the global risk aversion, external interest rates and internal political crises. The results of this study point to a decreasing marginal cost of international reserves and the need of considering it as endogenous in optimal reserves models based in cost minimization. Finally, the third case study implemented the Liquidity-at-Risk methodology suggested by Greenspan (1999), in order to assess the Brazilian reserves level adequacy in maintaining external liquidity. For the liquidity measure adopted - the ratio "reserves/short term external debt" (Guidotti's ratio) - it was found that the Brazilian reserves level held in Jun/2008 (US$200 billion) was roughly twice the necessary one to ensure a Guidotti's ratio above 1, with 99% probability, within 24, 36 or 48 months. In several alternative scenarios varying the short term external debt, short term internal debt, primary surplus, global risk aversion and external interest rates, the required initial reserves was in the range US$85-105 billion. An analysis of alternative policies' costs revealed the expected effect of higher reserves in decreasing the average debt service, although a dramatically higher impact would be obtained by an increase in primary surplus. Evidence suggest that the Brazilian authorities motivation for holding international reserves as high as US$200 billion may not be purely precautionary, pointing to the hypotheses of credibility gains and fiscal flexibility issues.

Submitted by Felipe Montenegro (fsmontenegro@bol.com.br) on 2018-09-30T16:50:09Z No. of bitstreams: 1 Dissertação Felipe Santiago Montenegro VF.pdf: 1151283 bytes, checksum: 7f4de8e37ff17ff90e6925d9fc5ffc0a (MD5) / Approved for entry into archive by Joana Martorini (joana.martorini@fgv.br) on 2018-10-01T21:33:33Z (GMT) No. of bitstreams: 1 Dissertação Felipe Santiago Montenegro VF.pdf: 1151283 bytes, checksum: 7f4de8e37ff17ff90e6925d9fc5ffc0a (MD5) / Approved for entry into archive by Suzane Guimarães (suzane.guimaraes@fgv.br) on 2018-10-02T13:24:09Z (GMT) No. of bitstreams: 1 Dissertação Felipe Santiago Montenegro VF.pdf: 1151283 bytes, checksum: 7f4de8e37ff17ff90e6925d9fc5ffc0a (MD5) / Made available in DSpace on 2018-10-02T13:24:09Z (GMT). No. of bitstreams: 1 Dissertação Felipe Santiago Montenegro VF.pdf: 1151283 bytes, checksum: 7f4de8e37ff17ff90e6925d9fc5ffc0a (MD5) Previous issue date: 2018-09-24 / O mercado de títulos de dívida offshore (bonds) é amplamente utilizado por empresas brasileiras a fim de obter recursos a taxas mais atraentes, melhorando seu perfil de endividamento assim como o retorno para o acionista. Outra vantagem neste tipo de captação é a possibilidade de as empresas mitigarem exposições cambiais inerentes ao seu negócio. O principal objetivo deste trabalho é entender como o mercado offshore avalia o risco de crédito das empresas brasileiras exportadoras de celulose. Foram utilizados dados de mercado da Bloomberg para avaliação do risco de crédito dos bonds, câmbio e risco-país. Como proxy para o risco de crédito foram utilizados dados de ZSpread de bonds com duration próxima. No caso do risco-país, foi utilizado o CDS do Brasil de 5 anos, inferior ao vencimento dos bonds analisados. Para o preço da celulose foi utilizada a mensuração da FOEX, amplamente reconhecida como referência de preço nesse mercado. O fator risco-país mostrou-se tão importante quanto o preço da celulose na avaliação do risco de crédito das empresas pelo mercado, conclusão que é condizente com os modelos reduced form. O câmbio mostrou ter uma relação positiva com o Z-Spread. / The bond market is widely used by Brazilian companies in order to obtain resources at attractive rates, improving their debt profile as well as the return to the shareholder. Another advantage in this type of funding is the ability of companies to mitigate currency exposures inherent in their business. The main objective of this work is to understand how the offshore market evaluates the credit risk of Brazilian pulp exporters. Bloomberg market data were used to assess the credit risk of bonds, foreign exchange and country risk. As proxy for credit risk the Z-Spread bond data was used, considering assets with similar durations. In the case of sovereign risk, Brazil’s 5-year CDS was used, lower than the maturity of the bonds analyzed. For the price of pulp, the measurement of FOEX, widely recognized as the reference price in this market, was used. The sovereign risk factor was as important as the price of pulp in the assessment of the companies' credit risk in the market, a conclusion that is consistent with the reduced form models. The exchange rate showed a positive relation with the ZSpread.

Submitted by Walter Gomes da Silva Junior (waltergomesjr@gmail.com) on 2018-08-28T19:07:10Z No. of bitstreams: 1 Spread Bancário América Latina - Walter Gomes.pdf: 1440714 bytes, checksum: 08cd6a32fa157e1bfba38dc04bc018a9 (MD5) / Approved for entry into archive by Joana Martorini (joana.martorini@fgv.br) on 2018-08-28T19:11:14Z (GMT) No. of bitstreams: 1 Spread Bancário América Latina - Walter Gomes.pdf: 1440714 bytes, checksum: 08cd6a32fa157e1bfba38dc04bc018a9 (MD5) / Approved for entry into archive by Isabele Garcia (isabele.garcia@fgv.br) on 2018-08-28T20:59:33Z (GMT) No. of bitstreams: 1 Spread Bancário América Latina - Walter Gomes.pdf: 1440714 bytes, checksum: 08cd6a32fa157e1bfba38dc04bc018a9 (MD5) / Made available in DSpace on 2018-08-28T20:59:33Z (GMT). No. of bitstreams: 1 Spread Bancário América Latina - Walter Gomes.pdf: 1440714 bytes, checksum: 08cd6a32fa157e1bfba38dc04bc018a9 (MD5) Previous issue date: 2018-07-27 / Os spreads bancários na América Latina apresentam altos patamares, quando comparados a outras regiões e economias do mundo. Este trabalho tem por objetivo a análise comparativa dos fatores determinantes do spread bancário, nas principais economias da América Latina, para isso, utilizaram-se dados agregados de 73 economias do mundo, sendo 11 delas países da América Latina. Partindo-se de uma base com 51 variáveis independentes, foram gerados modelos de regressão em painel. Os resultados obtidos evidenciam, que o patamar dos spreads praticados na América Latina, são principalmente impactados pela inadimplência, provisões de crédito, custos administrativos e de pessoal, concentração bancária e diversificação das receitas. / The banking spreads in Latin America show high levels when compared to other regions and economies of the world. This work has the objective of comparative analysis of the determinants factors of the banking spreads in the main economies of Latin America, for that, was used aggregated data of 73 economies in the world, 11 of which are Latin American countries. Starting from a base with 51 independent variables, panel regression models were generated. The results show that the level of spreads in Latin America is mainly impacted by nonperforming loans, the level provisions, administrative and personnel costs, banking concentration and revenues diversification.