Doctorat en sciences sociales, politiques et économiques / info:eu-repo/semantics/nonPublished

On étudie les théories de Yang-Mills. Pour ce faire, nous appliquons une nouvelle procédure de fixation de jauge qui vise à prendre en compte la présence des copies de Gribov. Ces copies correspondent à des solutions supplémentaires de la condition de jauge et ne sont pas prises en compte dans la procédure standard de Faddeev-Popov. Cette nouvelle procédure de fixation de jauge a d'abord été implémenté dans la jauge de Landau, où le régime de basse énergie a pu être étudié simplement par la théorie de perturbation et les propagateurs des gluons et des ghosts ont été trouvé en bon accord avec les résultats du réseau. Dans une première partie, nous appliquons cette procédure à une classe de jauges covariantes et non-linéaires (les jauges de Curci-Ferrari-Delbourgo-Jarvis). Nous montrons que ces jauges sont renormalisables en dimension quatre et donnons explicitement les expressions des constantes de renormalisation à une boucle. Nous calculons en théorie de perturbation les propagateurs de la théorie à l'ordre d'une boucle et implémentons le groupe de renormalisation. La seconde partie concerne l'étude du cas à température finie et de la transition de phase confinement-déconfinement. Nous travaillons dans une extention massive de la jauge de Landau-DeWitt. Nous calculons les propagateurs à une boucle et montrons qu'ils présentent de clairs signaux de la transition de phase à la différence de la jauge de Landau. / We investigate Yang-Mills theories. In particular, we follow a recently proposed new gauge-fixing procedure that aims at dealing with the presence of the so-called Gribov copies. These copies correspond to additional solutions to the gauge equation that are disregarded in the standard Faddeev-Popov procedure. This novel gauge-fixing approach was first implemented in the Landau gauge, where the low momentum regime was investigable by means of simple perturbation theory and the one-loop gluon and ghost propagators were found in good agreement with lattice results. In a first part, we extend this proposal to a class of nonlinear covariant (the Curci-Ferrari-Delbourgo-Jarvis) gauges . We prove that these gauges are renormalizable in four dimensions. We provide explicit expression of the renormalization constants at one-loop order. Then we compute the various propagators of the theory at one-loop order with and without renormalization group improvement. The second part of the thesis concerns the finite temperature case and in particular the study of the confinement-deconfinement phase transition. We work in the Landau-DeWitt gauge (a background extention of the Landau gauge) which allows for an explicit presence of an order parameter of the phase transition. This gauge is implemented following the previous gauge-fixing procedure. In particular it has been shown that the phase transition can be studied in perturbation theory. Here, we compute at one-loop order the gluon and ghost propagators (for SU(2) gauge group) and show that they display strong signals of the phase transition. This is to be put in regards with the results obtained for the Landau gauge propagators.

Os manguezais estão localizados na interface entre o continente e o oceano em regiões intertropicais, possuindo condições ambientais únicas. O objetivo deste trabalho foi avaliar a diversidade e o potencial biotecnológico da comunidade de Pseudomonas spp. em sedimentos de manguezais com diferentes estágios de preservação, no Estado de São Paulo. A diversidade de Pseudomonas spp. foi avaliada por meio da detecção do gene 16S rRNA e do gene gacA de isolados de Pseudomonas, como também por métodos independentes de cultivo. Dos 83 isolados obtidos, 55 foram positivos para o gene gacA. De acordo com as análises de DGGE e da biblioteca de clones, os diferentes manguezais apresentam comunidades de Pseudomonas bem distintas. Entre as espécies caracterizadas, P. nitroreducens e P. fluorescens foram predominantes. Pseudomonas de manguezais halotolerantes produzem AIA, ACC deaminase, NH3, solubilizam fosfato e fixam nitrogênio. Estudos demonstraram o potencial de Pseudomonas para promoção de crescimento de milho e redução dos efeitos do estresse salino sobre a planta. / Mangroves are located at the interface of continent and ocean in intertropical regions, possessing unique environmental conditions. The objective of this study was to evaluate the diversity and biotechnological potential of Pseudomonas spp. community in mangrove sediments under different stages of preservation in the São Paulo state. Pseudomonas spp. diversity was analyzed through the detection of 16S rRNA gene and gacA gene of Pseudomonas isolates, as well as through cultive independent methods. Of the 83 isolates, 55 were positive for gacA gene. According to DGGE and clone library analysis, the different mangroves showed very distinct Pseudomonas communities. Among the characterized species by 16S rRNA gene, P. nitroreducens and P. fluorescens were dominant. Pseudomonas mangrove halotolerant produce IAA, ACC deaminase, NH3, solubilize phosphate and fix nitrogen. Studies demonstrated the potential of Pseudomonas for maize growth promotion and reduce the effects of salt stress on the plant.

Beijerinckia sp., bactéria de vida livre fixadora de nitrogênio, comumente encontrada em solos tropicais lateríticos. A cianoficina produzida por cianobactérias é a única reserva nitrogenada intracelular descrita até hoje. O presente trabalho teve como principal objetivo verificar o acúmulo de material nitrogenado intracelular associado à Fixação Biológica de Nitrogênio em cinco isolados de Beijerinckia da rizosfera de cana-de-açúcar (Saccharum sp.). Os resultados mostraram um aumento na concentração de proteína celular total concomitantemente a atividade da nitrogenase durante a fase estacionária de todos os isolados. A fixação de nitrogênio durante esta fase sugere que o destino do nitrogênio fixado seriam os grânulos de armazenamento. A análise química desta reserva confirmou a presença de arginina em teor muito elevado em relação aos demais aminoácidos sugerindo uma reserva nitrogenada diferente da cianoficina. Em recombinantes de Escherichia coli confirmou-se um possível gene envolvido no armazenamento de material nitrogenado em Beijerinckia sp. / Beijerinckia sp. bacteria free-living nitrogen-fixing, commonly found in tropical lateritic soils. The cyanophycin produced by cyanobacteria is the only intracellular nitrogen reserve described to date. This study aimed to verify the intracellular buildup of nitrogen associated with Biological Nitrogen Fixation in five Beijerinckia isolated from the rhizosphere of sugarcane (Saccharum sp.). The results showed an increase in total cellular protein concentration concomitantly nitrogenase activity during the stationary phase of all isolates. The nitrogen fixation during this phase suggests that the fate of fixed nitrogen would be the storage granules. Chemical analysis of the reserve confirmed the presence of very high content of arginine in relation to other amino acids suggesting a different reserve of cyanophycin. In recombinant Escherichia coli confirmed a possible gene involved in nitrogen storage material in Beijerinckia sp.

Made available in DSpace on 2016-05-02T13:55:22Z (GMT). No. of bitstreams: 1 Marcio de Souza Dias Dissertacao.pdf: 1130526 bytes, checksum: 33886098250a3d16ad0626a969014e45 (MD5) Previous issue date: 2015-03-06 / Coordenacao de Aperfeicoamento de Pessoal de Nïvel Superior / The objective of this research was to analyze the diversity of nitrogen fixing bacteria associated and endophytic B. brizantha, study the potential the solubility of inorganic phosphates of iron and aluminum, produce acid-3-indole acetic (AIA) and to evaluate the effect of inoculation of these isolates in Brachiaria brizantha cv MG 05 Victoria. The bacteria were isolated from soil samples grown under Brachiaria and parts of plant tissue this grass, the dry and wet periods in the municipalities of Alfenas and Machado, southern Minas Gerais. Five semisolid culture media and semi-selective were used: FAM (Azospirillum amazonense), JMV (Burkholderia sp.), JNFb (Herbaspirillum spp.), LGI (A. amazonense) and NFb (Azospirillum spp.). The phosphate solubilization tests and AIA production were performed in vitro and were used as of 22 bacterial isolates selection criteria used in the inoculation of B. brizantha cv MG 5 Victoria, grown in pots containing 20 dm3 of soil. There were two cuts, in what form evaluated the following parameters: height (Al), width (LF) and leaf length (CF), number of tillers (NP), length (CR) and root dry mass (MSR) dry matter (DM), dry matter yield (PMS), neutral detergent fiber (NDF) and acid (ADF) and crude protein in dry matter (PBMS). A total of 332 isolates were obtained, most endophytic. The greatest number and diversity were from the city of Alfenas. During the rainy season was verified greater number and diversity of isolates in both municipalities, when compared to the dry season. Thirty-five isolates solubilized iron phosphate and 78 produced AIA, especially the isolated UNIFENAS 100-17, 21, 40 and 78, able to do both simultaneously. The inoculation of nitrogen fixing strains of endophytic origin and rhizospheric influenced the development of B. brizantha cv MG 5 victory, contributing to the production of MS, PMS and PBMS in the two cutting heights highlighting the UNIFENAS-100-16 isolated, 21, PBMS 78 whose content was more than 7%. / O objetivo desta pesquisa foi analisar a diversidade de bactérias diazotróficas associadas e endofíticas de Brachiaria brizantha, estudar o potencial destas em solubilizar fosfatos inorgânicos de ferro e alumínio, produzir ácido-3-indolacético (AIA) e avaliar o efeito da inoculação destes isolados em Brachiaria brizantha cv MG 05 Vitória. As bactérias foram isoladas de amostras de solos cultivados sob B. brizantha e partes de tecido vegetal desta gramínea, nos períodos seco e chuvoso, nos municípios de Alfenas e Machado, Sul de Minas Gerais. Foram utilizados cinco meios de cultura semissólidos e semisseletivos: FAM (Azospirillum amazonense), JMV (Burkholderia sp.), JNFb (Herbaspirillum spp.), LGI (A. amazonense) e NFb (Azospirillum spp.). Os testes de solubilização de fosfato e produção de AIA foram realizados in vitro e foram utilizados como critério de seleção dos 22 isolados bacterianos utilizados na inoculação de B. brizantha cv MG 5 Vitória, cultivada em vasos contendo 20 dm3 de solo. Foram realizados dois cortes, em que foram avaliados os seguintes parâmetros: altura (Al), largura (LF) e comprimento da folha (CF), número de perfilhos (NP), comprimento (CR) e massa seca da raiz (MSR), matéria seca (MS), produtividade de matéria seca (PMS), fibra em detergente neutro (FDN) e ácido (FDA) e a proteína bruta na matéria seca (PBMS). Foi obtido um total de 332 isolados, sendo a maioria endofíticos. O maior número e diversidade foram provenientes do município de Alfenas. No período chuvoso foi verificado maior número e diversidade de isolados em ambos os Municípios, quando comparado ao período da seca. Trinta e cinco isolados solubilizaram fosfato de ferro e 78 produziram AIA, destacando-se os isolados UNIFENAS 100-17, 21, 40 e 78, capazes de desempenhar ambas as funções simultaneamente. A inoculação de estirpes diazotróficas de origem endofíticas e rizosféricas influenciaram no desenvolvimento de B. brizantha cv MG 5 Vitória, contribuindo para a produção de MS, PMS e PBMS nas duas alturas de corte destacando-se os isolados UNIFENAS-100-16, 21, 78 cujo teor de PBMS foi superior a 7%.

A presente dissertação visa a analisar a cláusula de redução equitativa da indenização, introduzida no ordenamento jurídico brasileiro por meio do artigo 944, parágrafo único, do Código Civil de 2002. A aplicação da referida norma suscita intensos debates na doutrina e jurisprudência brasileiras, em especial no que tange à possibilidade de aplicação aos casos de responsabilidade objetiva. Nesse sentido, poder-se-ia argumentar que a redução da indenização impactaria na finalidade da norma expressa no artigo 927, parágrafo único, do Código Civil, inclusive no que tange aos incentivos para prevenção de danos. A partir de uma análise do contexto, evolução jurídica do conceito e seus elementos e funções, é realizada uma avaliação da possibilidade de aplicação e respectivos requisitos para a utilização do instituto de forma sistêmica e em consonância com o ordenamento jurídico vigente. Considerando que a Law and Economics permite ao intérprete antever os impactos da aplicação da norma na conduta dos agentes econômicos, em especial na internalização dos custos de prevenção, que são consequência direta de uma análise de custo e beneficio entre a prevenção e o pagamento da indenização pela causação de um dano, consiste em importante ferramenta à disposição da comunidade jurídica para a análise do terna proposto. Deste modo, o terna será analisado à luz da doutrina da Law and Economics, que traz importantes contribuições para a discussão do tema, que afeta de forma direta o comportamento dos agentes de mercado que desenvolvem atividades consideradas de risco. / The present dissertations aims at analyzing the equitable reduction o f indemnification, introduced in Brazilian legal system tbrough article 944, sole paragraph, o f the Civil Code of 2002. The application o f such rule raises intense debates in the Brazilian doctrine and case law, especially with regard to the possibility of application to cases of strict liability. In this sense, it could be argued that the reduction of indemnification would affect the purpose of the rule foreseen in article 927, sole paragraph, o f the Civil Code, including with regard to incentives to the prevention of damage. From an analysis ofthe context, legal evolution ofthe concept and its elements and functions, an evaluation is conducted to assess the applicability and respective requirements for the use of the institute in a systemic way and in accordance with the current legal system. Given that Law and Economics allows the interpreter to foresee the impacts that the application of the rule will have on the conduct of economic agents, especially regarding the internalization of prevention costs, which are a direct consequence of a cost and benefit analysis between prevention and payment of compensation due to a damage caused, it is an important tool available to the legal co=unity for the analysis of the proposed theme. Therefore, the subject will be analyzed in light ofthe Law and Economics doctrine that brings important contributions to the discussion, which directly affects the behavior of market agents who carry out activities considered risky.

La quantité croissante des données s’accompagne par l’augmentation du nombre de programmes de transformation de données, généralement des requêtes, et par la nécessité d’analyser et comprendre leurs résultats : (a) pourquoi telle réponse figure dans le résultat ? ou (b) pourquoi telle information n’y figure pas ? La première question demande de trouver l’origine ou la provenance des résultats dans la base, un problème très étudié depuis une 20taine d’années. Par contre, expliquer l’absence de réponses dans le résultat d’une requête est un problème peu exploré jusqu’à présent. Répondre à une question Pourquoi-Pas consiste à fournir des explications quant à l’absence de réponses. Ces explications identifient pourquoi et comment les données pertinentes aux réponses manquantes sont absentes ou éliminées par la requête. Notre travail suppose que la base de données n’est pas source d’erreur et donc cherche à fournir des explications fondées sur (les opérateurs de) la requête qui peut alors être raffinée ultérieurement en modifiant les opérateurs "fautifs". Cette thèse développe des outils formels et algorithmiques destinés au débogage et à la réparation de requêtes SQL afin de traiter des questions de type Pourquoi-Pas. Notre première contribution, inspirée par une étude critique de l’état de l’art, utilise un arbre de requête pour rechercher les opérateurs "fautifs". Elle permet de considérer une classe de requêtes incluant SPJA, l’union et l’agrégation. L’algorithme NedExplain développé dans ce cadre, a été validé formellement et expérimentalement. Il produit des explications de meilleure qualité tout en étant plus efficace que l’état de l’art.L’approche précédente s’avère toutefois sensible au choix de l’arbre de requête utilisé pour rechercher les explications. Notre deuxième contribution réside en la proposition d’une notion plus générale d’explication sous forme de polynôme qui capture toutes les combinaisons de conditions devant être modifiées pour que les réponses manquantes apparaissent dans le résultat. Cette méthode s’applique à la classe des requêtes conjonctives avec inégalités. Sur la base d’un premier algorithme naïf, Ted, ne passant pas à l’échelle, un deuxième algorithme, Ted++, a été soigneusement conçu pour éliminer entre autre les calculs itérés de sous-requêtes incluant des produits cartésien. Comme pour la première approche, une évaluation expérimentale a prouvé la qualité et l’efficacité de Ted++. Concernant la réparation des requêtes, notre contribution réside dans l’exploitation des explications polynômes pour guider les modifications de la requête initiale ce qui permet la génération de raffinements plus pertinents. La réparation des jointures "fautives" est traitée de manière originale par des jointures externes. L’ensemble des techniques de réparation est mis en oeuvre dans FixTed et permet ainsi une étude de performance et une étude comparative. Enfin, Ted++ et FixTed ont été assemblés dans une plate-forme pour le débogage et la réparation de requêtes relationnelles. / With the increasing amount of available data and data transformations, typically specified by queries, the need to understand them also increases. “Why are there medicine books in my sales report?” or “Why are there not any database books?” For the first question we need to find the origins or provenance of the result tuples in the source data. However, reasoning about missing query results, specified by Why-Not questions as the latter previously mentioned, has not till recently receivedthe attention it is worth of. Why-Not questions can be answered by providing explanations for the missing tuples. These explanations identify why and how data pertinent to the missing tuples were not properly combined by the query. Essentially, the causes lie either in the input data (e.g., erroneous or incomplete data) or at the query level (e.g., a query operator like join). Assuming that the source data contain all the necessary relevant information, we can identify the responsible query operators formingquery-based explanations. This information can then be used to propose query refinements modifying the responsible operators of the initial query such that the refined query result contains the expected data. This thesis proposes a framework targeted towards SQL query debugging and fixing to recover missing query results based on query-based explanations and query refinements.Our contribution to query debugging consist in two different approaches. The first one is a tree-based approach. First, we provide the formal framework around Why-Not questions, missing from the state-of-the-art. Then, we review in detail the state-of-the-art, showing how it probably leads to inaccurate explanations or fails to provide an explanation. We further propose the NedExplain algorithm that computes correct explanations for SPJA queries and unions there of, thus considering more operators (aggregation) than the state of the art. Finally, we experimentally show that NedExplain is better than the both in terms of time performance and explanation quality. However, we show that the previous approach leads to explanations that differ for equivalent query trees, thus providing incomplete information about what is wrong with the query. We address this issue by introducing a more general notion of explanations, using polynomials. The polynomial captures all the combinations in which the query conditions should be fixed in order for the missing tuples to appear in the result. This method is targeted towards conjunctive queries with inequalities. We further propose two algorithms, Ted that naively interprets the definitions for polynomial explanations and the optimized Ted++. We show that Ted does not scale well w.r.t. the size of the database. On the other hand, Ted++ is capable ii of efficiently computing the polynomial, relying on schema and data partitioning and advantageous replacement of expensive database evaluations by mathematical calculations. Finally, we experimentally evaluate the quality of the polynomial explanations and the efficiency of Ted++, including a comparative evaluation.For query fixing we propose is a new approach for refining a query by leveraging polynomial explanations. Based on the input data we propose how to change the query conditions pinpointed by the explanations by adjusting the constant values of the selection conditions. In case of joins, we introduce a novel type of query refinements using outer joins. We further devise the techniques to compute query refinements in the FixTed algorithm, and discuss how our method has the potential to be more efficient and effective than the related work.Finally, we have implemented both Ted++ and FixTed in an system prototype. The query debugging and fixing platform, short EFQ allows users to nteractively debug and fix their queries when having Why- Not questions.

LLM / Department of Mercantile Law / The study critically analyses the concurrent enforceability of restraint of trade and garden leave in South African Labour law. The study seeks to answer the question of whether or not the simultaneous enforceability of restraint of trade agreements and garden leave is reasonable. Designed within a qualitative paradigm primarily based on a critical literature review, the study employs a doctrinal approach to establish the contemporary legal position in respect of the simultaneous enforceability of restraint of trade agreements and garden leave in South African Labour law. The objectives pursued by the study are to mitigate the controversies and clear the confusion relating to the enforceability of restraint of trade agreements; to justify the doctrine of restraint of trade; assess the reasonableness of the simultaneous enforceability of garden leave and restraint of trade; examine the onus of proof in matters dealing with the enforceability of restraint of trade agreements; test the constitutionality of restraint of trade agreements; evaluate the relationship between restraint of trade agreements and garden leave; and propose practical recommendations that can be employed to address identified legal flaws in the context of the topic. Structurally, the study begins with unpacking the background to the research topic, the history, origin and rationality of restraint of trade agreements together with an assessment of their enforceability. It further examines the effect of garden leave on restraint of trade agreements, outlines comparative perspectives on restraint of trade, including aspects relating to garden leave and highlights lessons South Africa may learn from the selected jurisdictions. Finally, the study recommends that South African jurisprudence should be developed to shift the burden of proof to employers to prove reasonableness of garden leave and restraint of trade agreements, to impose an obligation on employers to pay former employees for rendering them jobless and to set a maximum period that an employee can be prevented to compete or be employed by employer’s competitors. / NRF

Last years, lead time, flexibility, cost, and quality have become significant factors for the manufacturing industry. This also applies to gears, which could be manufactured using hobbing and grinding. Fixing systems are used to precisely center and fully fix gears to reach high quality. These are expensive and not flexible which requires a new one for each gear dimension. This limits the production of prototypes and so new product for the market. Developing a 3D concept for affordable and flexible fixing is the purpose. Through literature research, analyzing the current process, discussions with the company, desk research, and benchmarking, requirements are made for the new concept. Then brainstorming sessions are done to come up with new concepts. The concepts are analyzed, discussed with the company, and combined into two better concepts. Even though the higher flexibility of the other concept, the robustness of the winning concept “CoNut”. The principle is that only a few parts have to be changed instead of the whole system. The concept is further developed in 3D, where design for cost and manufacturing are applied. Finally, test procedures are drafted to validate the concept against therequirements. While some require a prototype, others are already validated by using the 3D model. Ultimately, an affordable and more flexible fixing system is developed as a 3D concept, by using a structural design process, which is likely to meet all the requirements. Since the model is cheaper and easier to change within meeting the other requirements, the purpose is reached.

<p dir="ltr">The Global Navigation Satellite System (GNSS) is heavily relied on for the navigation of Earth satellites. For satellites in cislunar space and beyond, GNSS is not readily available. As a result, other sources such as NASA's Deep Space Network (DSN) must be relied on for navigation. However, DSN is overburdened and can only support a small number of satellites at a time. Furthermore, communication with external sources can become interrupted or deprived in these environments. Given NASA's current efforts towards cislunar space operations and the expected increase in cislunar satellite traffic, there will be a need for more autonomous navigation options in cislunar space and beyond.</p><p dir="ltr">In this thesis, a navigation system capable of accurate and computationally efficient orbit determination in these communication-deprived environments is proposed and investigated. The emphasis on computational efficiency is in support of cubesats which are constrained in size, cost, and mass; this makes navigation even more challenging when resources such as GNSS signals or ground station tracking become unavailable.</p><p dir="ltr">The proposed navigation system, which is called GRAVNAV in this thesis, involves a two-satellite formation orbiting a planet. The primary satellite hosts an Extended Kalman Filter (EKF) and is capable of measuring the relative position of the secondary satellite; accurate attitude estimates are also available to the primary satellite. The relative position measurements allow the EKF to estimate the absolute position and velocity of both satellites. In this thesis, the proposed navigation system is investigated in the two-body and three-body problems.</p><p dir="ltr">The two-body analysis illuminates the effect of the gravity model error on orbit determination performance. High-fidelity gravity models can be computationally expensive for cubesats; however, celestial bodies such as the Earth and Moon have non-uniform and highly-irregular gravity fields that require complex models to describe the motion of satellites orbiting in their gravity field. Initial results show that when a second-order zonal harmonic gravity model is used, the orbit determination accuracy is poor at low altitudes due to large gravity model errors while high-altitude orbits yield good accuracy due to small gravity model errors. To remedy the poor performance for low-altitude orbits, a Gravity Model Error Compensation (GMEC) technique is proposed and investigated. Along with a special tuning model developed specifically for GRAVNAV, this technique is demonstrated to work well for various geocentric and lunar orbits.</p><p><br></p><p dir="ltr">In addition to the gravity model error, other variables affecting the state estimation accuracy are also explored in the two-body analysis. These variables include the six Keplerian orbital elements, measurement accuracy, intersatellite range, and satellite formation shape. The GRAVNAV analysis shows that a smaller intersatellite range results in increased state estimation error. Despite the intersatellite range bounds, semimajor axis, measurement model, and measurement errors being identical for both orbits, the satellite formation shape also has a strong influence on orbit determination accuracy. Formations that place both satellites in different orbits significantly outperform those that place both satellites in the same orbit.</p><p dir="ltr">The three-body analysis primarily focuses on characterizing the unique behavior of GRAVNAV in Near Rectilinear Halo Orbits (NRHOs). Like the two-body analysis, the effect of the satellite formation shape is also characterized and shown to have a similar impact on the orbit determination performance. Unlike the two-body problem, however, different orbits possess different stability properties which are shown to significantly affect orbit determination performance. The more stable NRHOs yield better GRAVNAV performance and are also less sensitive to factors that negatively impact performance such as measurement error, process noise, and decreased intersatellite range.</p><p dir="ltr">Overall, the analyses in this thesis show that GRAVNAV yields accurate and computationally efficient orbit determination when GMEC is used. This, along with the independence of GRAVNAV from GNSS signals and ground-station tracking, shows that GRAVNAV has good potential for navigation in cislunar space and beyond.</p>