Made available in DSpace on 2014-12-17T15:25:10Z (GMT). No. of bitstreams: 1 RicardoJVC.pdf: 1963869 bytes, checksum: df6d037b66a42df9fd62e79997d2d6db (MD5) Previous issue date: 2008-08-22 / Analyses the presence of new standards of habitation detected in the construction of the region called Cidade Nova, in the first s years of the XX century. Associates the presence of these new patterns with the historical moment lived by the capital, marked by the urban modernization and by the changes of local life. Map voices that, introduced by the republican groups since 1889, pronounced the overcome of the old city of the XIX century asseverated a new model of town. Make use, as fundamental fonts of research, of the urban chronicles produced by the local intellectuals and the newspapers, like A Rep?blica. Dialog with chronics that includes since propositions about the colonial past until the preoccupations about the acting of the State on how to order the public space. Identifies on those texts the political motivations and the elements whose where inherent to capitalism that accelerated the changes occurred in the urban space. Demonstrates the gradual occupation of Cidade Nova as an important modification happened in the city from that time on. That neighborhood adopted a new model on how to construct the houses of their citizens and helped to promote the urban life as a whole. From now on, Natal has a space meant for the home of their richest families. Recognizes, from many ways, many discourses, manners of living that was legitimized by the changing of the XIX to the XX century and has his highest point in the 1920?s. And it was representative of the strong attachment about the habits of refinery and order in the essence of the private life of the local urban elites / Analisa a presen?a de novos padr?es de moradia em Natal, detectados na constru??o da regi?o da Cidade Nova, nos primeiros anos do s?culo XX. Associa a presen?a desses novos padr?es habitacionais ao momento hist?rico vivido pela capital, marcado pela moderniza??o urbana e pela mudan?a nos modos de vida. Mapeia as vozes que, consolidadas nos grupos republicanos desde 1889, pronunciavam a supera??o da cidade antiga do s?culo XIX e afirmavam um novo modelo de cidade. Utiliza como fontes principais cr?nicas urbanas produzidas por intelectuais locais e por peri?dicos, destacadamente A Rep?blica. Trabalha com cr?nicas que incluem desde enunciados sobre o passado colonial at? as preocupa??es sobre a atua??o do Estado na ordena??o do espa?o publico. Identifica nas cr?nicas as motiva??es pol?ticas e os elementos inerentes ao pr?prio capitalismo que favoreceram para as mudan?as ocorridas no espa?o urbano. Demonstra que a gradual ocupa??o da Cidade Nova, com um padr?o inovador na arquitetura das casas e na organiza??o do espa?o p?blico, representou importante muta??o na cidade, que passou a dispor de uma ?rea estritamente residencial e destinada a abrigar as fam?lias de maior poder econ?mico. Identifica, a partir dos v?rios discursos, maneiras de viver que se afirmaram na transi??o do s?culo desde o in?cio do s?culo XX e atingiram seu auge a partir da d?cada de 1920, sendo estas representativas do apego ao refinamento e ? ordena??o no ?mbito da vida privada de suas elites urbanas

Made available in DSpace on 2014-12-17T15:25:17Z (GMT). No. of bitstreams: 1 AdrianaGA_DISSERT.pdf: 2159364 bytes, checksum: 5631ae6adf44f0337d03ec915ab34035 (MD5) Previous issue date: 2011-08-26 / Cette dissertation a pour but d?analyser la ville de S?o Lu?s do Maranh?o pendant la Premi?re Republique, d?apr?s le roman Vencidos e Degenerados, de Jos? do Nascimento Moraes, publi? en 1915. ? partir des rapports entre l?Histoire et la Litt?rature, nous nous int?ressons ? la fa?on dont l?auteur ?crit l?histoire d?une ville qui, apr?s la fin de l?esclavage et l?installation de la Republique, conserve des anciens pr?jug?s de race et reste plong?e dans l?immobilit? economique. Le roman fait partie d?un ensemble d?oeuvres scientifiques et litt?raires d?une g?neration connue sous le nom de Novos Atenienses (nouveaux ath?niens), laquelle discutait la crise ?conomique et culturelle v?cue par le Maranh?o au tournant des XIXe et XXe si?cles. Le discours formul? par les nouveaux-ath?niens comprennait des el?ments nostalgiques associ?s au culte des lettres envisageant la conqu?te de la r?conaissance litt?raire et le d?sir d?adapter la ville de S?o Luis aux mod?les de progr?s et modernisation de la p?riode r?publicaine. Dans ce contexte, Moraes introduit les th?mes li?s ? la discrimination raciale qui demerait apr?s la fin de l?esclavage, qu?il consid?rait un obstacle au progr?s de la capitale de Maranh?o, et aussi la cause des p?rsecutions litt?raires dont il ?tait victime. On a analis? le roman en cherchant compreendre les rapports entre les individus et les rapports qui?ils entretienent avec les spaces de la ville, ? partir de questions d?ordre litt?raire, raciale et urbaine. En guise de conclusion, la narration de l?oeuvre est d?vellop?e de fa?on que la ville, peupl?e de gens de couleurs, sert ? legitim?e l?oeuvre litt?raire de Moraes, dont le nom a ?t? oubli? dans les principaux cercles litt?raires de la capitale pendant la p?riode examin?e / O presente trabalho tem por objetivo analisar a cidade de S?o Lu?s do Maranh?o na Primeira Rep?blica presente do romance Vencidos e Degenerados de Jos? do Nascimento Moraes, publicado em 1915. A partir do di?logo entre Hist?ria e Literatura, investigamos de que maneira o autor elabora a hist?ria de uma cidade que ap?s a liberta??o dos escravos e a chegada da Rep?blica permanece atrelada a antigos preconceitos de cor e mergulhada em uma letargia econ?mica devido a perman?ncias de ordem social e cultural. O romance faz parte de um conjunto de obras cient?ficas e liter?rias de uma gera??o conhecida como Novos Atenienses, que pretendia problematizar e propor solu??es para a crise econ?mica e cultural pela qual passava o Maranh?o na virada do s?culo XIX para o XX. O discurso elaborado pelos neoatenienses combinava elementos saudosistas relacionados ao cultivo das letras para a obten??o do reconhecimento liter?rio e os anseios de tornarem a cidade de S?o Lu?s condizente com os ideais de progresso e moderniza??o caracter?sticos do per?odo republicano. A esse contexto, Moraes insere discuss?es relacionadas aos preconceitos racial e social que persistiram ap?s a Aboli??o da Escravid?o e a Proclama??o da Rep?blica, considerados, por ele, as causas do atraso no desenvolvimento urbano da capital maranhense e das persegui??es liter?rias sofridas por ele. Analisamos o romance buscando compreender as rela??es dos indiv?duos entre si e com os espa?os da cidade a partir dessas quest?es liter?rias, raciais e urbanas. Entendemos que a narrativa da obra ? constru?da de maneira que a cidade, povoada por personagens negros, serve para legitimar a obra liter?ria de Moraes , cujo nome foi silenciado nos principais c?rculos liter?rios da capital durante o per?odo por n?s estudado

Made available in DSpace on 2014-12-17T15:25:17Z (GMT). No. of bitstreams: 1 AndersonDSB_DISSERT.pdf: 4868485 bytes, checksum: 66fb82a21534bbaa6e3f0e444688eef7 (MD5) Previous issue date: 2012-08-31 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This paper has the imaginary names as a theme, from which we aim to analyze the imaginaries and invested interests that characterized the implementation and the legitimation of the First Republic in Rio Grande do Norte (1889 1930), making the process of registering names history in that place. For the construction of our object, we studied laws and provincial, state and municipal decrees; annual messages of governors; articles of the following newspapers O Povo, A Rep?blica, Di?rio do Natal, O Seridoense, A Not?cia and Jornal das Mo?as; the local cartography and historiography that talk about the study of names. The use of these resources, allied to the empiric method, was driven by a theoretic methodological contribution based on the history of the political imaginary, as discussed by Cornelius Castoriadis, Ren? R?mond, Michel de Certeau and Maria Dick. For the understanding of the imaginaries that (de)limited the spaces of Rio Grande do Norte concerning its names during the First Republic, we bring moment back to the two last imperial decades moment of cleavage between Empire and Republic essential for the fomentation of the imaginary that embodied the organization of our study. From this period, we observe, through the names of some cities, how the northern space would be aligned to the imaginary dynamic of the new political system of the nation, and it had followed to a redirection process of the giving names action, according to the interests of the family organization Albuquerque Maranh?o, revealed while determining the names of cities, towns, streets, schools, buildings, etc., in thankfulness to the memory of its members. In the sequence we verified how a new dynamic of giving names helped to understand the process of political transition from the Coast to the Sert?o, and at the same time affirmed the power of the political and economical seridoense elite towards the government of the state in the two last decades of the First Republic / Esse trabalho tem como tem?tica imagin?rios topon?micos, a partir da qual objetivamos analisar os imagin?rios e interesses investidos que caracterizaram a implanta??o e a legitima??o da Primeira Rep?blica (1889-1930) no Rio Grande do Norte, historicizando o processo de toponimiza??o de tal espa?o. Para a constru??o de nosso objeto perscrutamos leis e decretos provinciais, estaduais, e municipais; mensagens anuais de governadores; artigos dos jornais O Povo, A Rep?blica, Di?rio do Natal, O Serid?ense, A Not?cia, e Jornal das Mo?as; a cartografia, e a historiografia local que trata da topon?mia. A utiliza??o dessas fontes aliadas a empiria foram conduzidas por um aporte te?rico-metodol?gico baseado na hist?ria do imagin?rio pol?tico atrav?s de Cornelius Castoriadis, Ren? R?mond, Michel de Certeau e Maria Dick. Para a compreens?o dos imagin?rios que (de)marcaram toponimicamente os espa?os do Rio Grande do Norte durante a Primeira Rep?blica inicialmente retornaremos ?s duas ?ltimas d?cadas imperiais, enquanto momento de clivagem entre Imp?rio e Rep?blica, fundamental para a fomenta??o dos imagin?rios que corporificaram a organiza??o de nossa problem?tica. Este primeiro olhar trata de observar atrav?s dos nomes de algumas cidades como o espa?o norte-rio-grandense deveria est? alinhado com a din?mica imagin?ria do novo regime pol?tico da na??o, seguindo para um processo de redirecionamento das pr?ticas nomeativas em conformidade com a organiza??o familiar Albuquerque Maranh?o ao enunciar nos nomes de cidades, vilas, ruas, escolas, edif?cios, etc o reconhecimento ? mem?ria de seus membros, para na sequ?ncia verificar como uma nova din?mica nomeativa ajudou a entender o processo de transi??o pol?tica do Litoral para o Sert?o, e ao mesmo tempo afirmando o poder da elite pol?tica e econ?mica seridoense ? frente do governo do estado nas duas ?ltimas d?cadas da Primeira Rep?blica

Submitted by Aline Batista (alinehb.ufpel@gmail.com) on 2018-05-16T13:41:30Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_Aline_de_Oliveira_Rodrigues.pdf: 787004 bytes, checksum: 42043083bf6f4a2ee9080a2164a23e88 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2018-05-16T20:21:01Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_Aline_de_Oliveira_Rodrigues.pdf: 787004 bytes, checksum: 42043083bf6f4a2ee9080a2164a23e88 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2018-05-16T20:21:17Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_Aline_de_Oliveira_Rodrigues.pdf: 787004 bytes, checksum: 42043083bf6f4a2ee9080a2164a23e88 (MD5) / Made available in DSpace on 2018-05-16T20:21:17Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_Aline_de_Oliveira_Rodrigues.pdf: 787004 bytes, checksum: 42043083bf6f4a2ee9080a2164a23e88 (MD5) Previous issue date: 2015-04-30 / Sem bolsa / O setor hoteleiro vem se expandindo mundialmente a cada ano e dentre os serviços oferecidos, a gastronomia é um dos mais requisitados, através da qual busca-se a satisfação do cliente, oferecendo produtos seguros e de qualidade. Paralelamente ao incremento do turismo, a incidência de doenças de origem alimentar está crescendo em todo mundo. Acredita-se que o consumo de alimentos contaminados seja a principal causa de doenças em turistas. Neste contexto o objetivo deste estudo foi avaliar a aplicação das boas práticas em restaurantes hoteleiros da cidade de Pelotas/RS e Rio Grande/RS e relacioná-las com a qualidade microbiológica dos alimentos oferecidos, além de identificar fontes de contaminação. O setor de alimentos e bebidas (A&B) de quatro hotéis foi avaliado quanto às condições higiênicossanitárias em duas visitas, com intervalo mínimo de 30 dias, através de aplicação de check list fundamentado na norma da RDC 216/2004, e de análises microbiológicas de amostras coletadas no local. Foram realizadas coletas de amostras de superfícies de utensílios, equipamentos e mãos de manipuladores para contagem de Staphylococcus coagulase positiva e de coliformes termotolerantes. Isolados obtidos das culturas dessas contagens foram comparados através de perfis de genéticos obtidos por rep-PCR. Considerando as não conformidades observadas no check list, na primeira visita apenas um hotel foi classificado como ótimo, dois foram classificados como bons e um recebeu a classificação ruim. Entretanto, na segunda visita o hotel classificado como ruim passou para bom, devido à realização de melhorias no restaurante. Alguns resultados das análises microbiológicas apresentaram limite acima do permitido para a contagem dos micro-organismos analisados, identificando falha na aplicação das boas práticas. Através da técnica de rep-PCR, foi identificada uma mesma cepa em amostras de queijo e mãos, manteiga e tábua de corte, queijo e tábua de corte e salada de frutas e mãos, evidenciando contaminação cruzada devido falhas no processo de higiene e manipulação dos alimentos. / The hotel industry has been expanding every year and among the services offered, the cuisine is one of the most requested, which seeks customer satisfaction by offering safe and quality products. Parallel to the tourism development, the incidence of foodborne diseases is growing worldwide. It is believed that the consumption of contaminated food is the major cause of disease in tourists. This study goal was to evaluate the application of best practices in hotel restaurants in the cities of Pelotas/RS and Rio Grande/RS and relate it to the microbiological quality of the food offered, besides to identify sources of contamination. The sector of food and beverages (F&B) of four hotels was evaluated in two visits with an interval of 30 days regarding hygiene-sanitary conditions, by application of check list and microbiological analyzes of samples collected on site. Surface, utensils, equipment and hands handlers samples have been collected for counting coagulase positive Staphylococcus and thermotolerant coliform. Isolates obtained from these counting cultures were compared by bands profiles obtained by rep-PCR. According to the non-conformity observed in the check list on the first visit, only one hotel was rated as great, two were classified as good and one received a bad rating. However, on the second visit, the one considered bad got a good rate due to improvements in its unit. Some microbiological analysis showed a limit above the allowed for the count of analyzed microorganisms, identifying failure in the hygiene-sanitary process. By rep-PCR, was identified the same strain in samples of cheese and hands, butter and cutting board, cutting board and cheese and fruit salad and hands, showing cross-contamination due to flaws in the process of care and handling of food.

Les codes de simulation du cycle du combustible nucléaire sont des outils permettant d’évaluer les stratégies futures du cycle du combustible nucléaire et de comprendre la physique de ce cycle. Dans le contexte d’incertitude entourant l’évolution future du parc nucléaire français, notamment concernant le déploiement de Réacteurs à Neutrons Rapides au sodium (RNR-Na), la problématique de cette thèse est d’étudier des solutions alternatives de gestion du plutonium et des autres noyaux lourds, basées sur les Réacteurs à Eau Pressurisés (REP). Les stratégies étudiées s’appuient sur deux hypothèses. La première suppose un retard important dans le déploiement des RNR-Na, impliquant une stratégie d’attente visant à stabiliser l’inventaire en plutonium. La deuxième hypothèse suppose un abandon de la stratégie de déploiement des RNR. Dans ce cadre, une stratégie d’incinération du plutonium a été étudiée pour quantifier la capacité de réduction de l’inventaire par les REP. Le code de simulation CLASS, développé par le CNRS/IN2P3 et l’IRSN, est utilisé. Le multi-recyclage du plutonium en REP requiert un combustible dédié. Des développements ont été réalisés pour modéliser le combustible étudié, composé de MOX sur un support d'uranium enrichi. Une méthodologie innovante d’évaluation de scénarios nucléaires basée sur l’analyse globale de sensibilité a été appliquée. Cette méthode a permis d’identifier des scénarios de référence pour la stabilisation et la réduction de l’inventaire en plutonium et actinides mineurs. Des simulations du cycle détaillées ont été réalisées afin d'analyser la capacité des REP à gérer le plutonium à l’échelle du cycle. / Nuclear fuel cycle simulation codes are used to evaluate fuel cycle future strategies and understand the nuclear fuel cycle physics. In the context of uncertainty related to the future of French nuclear fleet, especially on theSodium Fast Reactor (SFR) deployment, the present work aims to study alternative solutions for plutonium and heavy isotopes management, based on Pressurized Water Reactor (PWR). Two hypothesis have been formulated to identify strategies. First, a delay has been expected in SFR deployment which induces a stabilization of plutonium inventory before SFR integration. The second hypothesis is based on the assumption that SFR won’t be deployed in France. For this specific case, a plutonium incineration strategy has been studied to quantify the PWR plutonium inventory reduction capacity. Fuel cycle simulations are performed using the fuel cycle simulator CLASS developed by the CNRS/IN2P3 in collaboration with IRSN. Plutonium multi-reprocessing in thermal reactor requires an innovative fuel. Developments have been made to simulate a fuel composed of MOX on enriched uranium support. An innovative methodology for fuel cycle simulation evaluation, based on Global Sensitivity Analysis, has been applied. This methodology leads to reference scenarios identification for plutonium and minor actinides inventories stabilization and reduction. Fuel cycle detailed simulations have been performed to produce fuel cycle data, to analyze PWR plutonium management at the cycle scale.

Tato práce se zabývá simulacemi neholonomních mechanismů, konkrétně robotických hadů. V práci jsou uvedeny základní poznatky geometrické teorie řízení. Tyto poznatky jsou využity k odvození řídících modelů robotických systémů a následně jsou tyto modely simulovány v prostředí V-REP.

The aim of this master thesis is to make research of Open Source software, which are used for simulation autonomous robots. At the begining is performed research of selected robotic simulators. In the first part of this work is to get familiar with robotic simulator Gazebo and robotic framework ROS. The second part of this work deals with simulating and subsequent implementation of choosen robotic tasks through the simulator Gazebo and the ROS framework.

Dans la mucoviscidose, le tableau clinique est dominé par les infections respiratoires qui constituent la cause majeure de morbidité. Diverses espèces fongiques sont décrites dans ces infections, notamment les Scedosporium et le complexe Rasamsonia argillacea pour lesquels les connaissances restent limitées. Dans ce travail, nous avons évalué l’intérêt de l’amplification des séquences répétitives de l’ADN pour la différenciation spécifique et infraspécifique de ces champignons. La rep-PCR a d’abord été appliquée à l’analyse d'isolats du genre Scedosporium. La rep-PCR a produit des résultats concordants avec ceux obtenus par séquençage du gène de la bêta-tubuline, amplification aléatoire de fragments d’ADN polymorphes et séquençage multi-loci. Elle permet également l’identification précise des espèces au sein du complexe R. argillacea. L’analyse des résultats obtenus sur 116 isolats a montré la capacité de ces champignons à coloniser de manière chronique les voies respiratoires, un même profil électrophorétique étant observé généralement chez un même patient. Enfin, nous avons produit de nouvelles données sur l’écologie des Scedosporium en étudiant différents biotopes au Maroc. Comme précédemment rapporté,ces champignons préfèrent les environnements impactés parles activités humaines. On les rencontre dans des sols de pH neutre, riches en matières organiques et pauvres en sels. Enfin, si S. apiospermum était l’espèce la plus abondante, S. boydii, S. aurantiacum et S. dehoogii ont été rencontrés avec des fréquences comparables. En conclusion, les données générées renforcent nos connaissances sur l’épidémiologie des infections causées par ces pathogènes émergents. / In cystic fibrosis (CF), respiratory infections are the leading cause of morbidity and mortality. Bacteria are the most common causative agents of these infections, but an increasing number of fungal species may also be found, including Scedosporium species and species of the Rasamsonia argillacea complex. In order to improve our knowledge on the epidemiology of these infections, here we evaluated the interest of PCR amplification of repetitive DNA sequences (rep-PCR) for species identification and strain delineation. rep-PCR was applied to the retrospective analysis of a panel of 63 isolates belonging to the Scedosporiumgenus. Results were consistent with those obtained by beta-tubulingene sequencing, random amplification of polymorphic DNA and Multilocus Sequence Typing. rep-PCR also permitted precise species identification in the R. argillacea complex. Analysis of the data obtained on 116 isolates revealed the capacity of these fungi to chronically colonize the airways of patients with CF, a unique electrophoretic profile being observed usually for each patient. Finally, we produced in this thesis new data about the ecology of Scedosporium species by studying different biotopes in Morocco. As previously reported, these fungi are mainly found in human-impacted areas. Also they prefer soils with a neutral pH, a high organic matter content and a very low mineral salts content. In addition, if S. apiospermum was by far the predominant species, S. boydii, S. aurantiacum and S. dehoogii were encountered with similar frequencies. In conclusion, data provided here reinforce our knowledge on the epidemiology of the infections caused by these emerging pathogens.

Les topoisomérases (topos) de type IA jouent un rôle primordial dans le maintien et l’organisation du génome. Cependant, les mécanismes par lesquels elles contrôlent cette stabilité génomique sont encore à approfondir. Chez E. coli, les deux principales topoisomérases de type IA sont la topo I (codée par le gène topA) et la topo III (codée par le gène topB). Il a déjà été montré que les cellules dépourvues des topos I et III formaient de très longs filaments dans lesquels les chromosomes ne sont pas bien séparés. Comme ces défauts de ségrégation des chromosomes sont corrigés par l’inactivation de la protéine RecA qui est responsable de la recombinaison homologue, il a été émis comme hypothèse que les topoisomérases de type IA avaient un rôle dans la résolution des intermédiaires de recombinaison afin de permettre la séparation des chromosomes. D’autre part, des études réalisées dans notre laboratoire démontrent que le rôle majeur de la topoisomérase I est d’empêcher la formation des R-loops durant la transcription, surtout au niveau des opérons rrn. Ces R-loops on été récemment identifiés comme des obstacles majeurs à l’avancement des fourches de réplication, ce qui peut provoquer une instabilité génomique. Nous avons des évidences génétiques montrant qu’il en serait de même chez nos mutants topA. Tout récemment, des études ont montré le rôle majeur de certaines hélicases dans le soutien aux fourches de réplication bloquées, mais aussi une aide afin de supprimer les R-loops. Chez E. coli, ces hélicases ont été identifiées et sont DinG, Rep et UvrD. Ces hélicases jouent un rôle dans la suppression de certains obstacles à la réplication. Le but de ce projet était de vérifier l’implication de ces hélicases chez le mutant topA en utilisant une approche génétique. Étonnamment, nos résultats montrent que la délétion de certains de ces gènes d’hélicases a pour effet de corriger plutôt que d’exacerber des phénotypes du mutants topA qui sont liés à la croissance et à la morphologie des nucléoides et des cellules. Ces résultats sont interprétés à la lumière de nouvelles fonctions attribuées aux topoisomérases de types IA dans la stabilité du génome. / Type 1A topoisomerases (topos) play a vital role in the maintenance and organization of the genome. However, the mechanisms by which they control genome stability still remain to be explored. In E. coli, the two type IA topoisomerases are topo I (encoded by topA) and topo III (encoded by topB). It has been shown that cells lacking topo I and III form very long filaments in which the chromosomes are not well separated. As the chromosome segregation defects are corrected by inactivation of the RecA protein, that is responsible for homologous recombination, it has been hypothesized that type IA topoisomerases have a role in the resolution of recombination intermediates to allow chromosome segregation. On the other hand, studies in our laboratory have shown that the major role of topoisomerase I is to prevent the formation of R-loops during transcription, especially at the rrn operons. These R-loops have been recently identified as major roadblocks to the progression of replication forks, which can cause genomic instability. We have genetic evidence suggesting similar effects may occur in our topA mutants. More recently, studies have shown the important role of certain helicases in eliminating roadblocks for replication forks that could sometimes be R-loops. In E. coli, these helicases have been identified and they are DinG, Rep and UvrD. The purpose of this project was to study the roles of these helicases in our topA mutant, using a genetic approach. Surprisingly, our results show that deletions of some of these genes have the effect of correcting rather than exacerbating topA mutant phenotypes that are related to the growth and cell and nucleoid morphology. These results are interpreted in the light of new functions assigned to the type IA topoisomerases in genome stability.

Les systèmes de maintien situés sur les structures assemblages-combustibles des réacteurs nucléaires à eau sous pression (REP) sont constitués d'un empilement de lames qui agissent à la fois, comme élément accommodant les incompatibilités thermiques résultant des différences de coefficients de dilatation Acier, alliages de zirconium et principalement, comme système permettant de limiter les effets hydrodynamiques induits par le passage du fluide caloporteur à travers les assemblages. Actuellement, l'alliage 718 est le matériau constitutif de ces ressorts à lames. Il présente les performances en service nécessaires et suffisantes pour répondre aux sollicitations de ces systèmes ainsi qu'aux exigences des autorités de sûreté (dans les conditions actuelles de fonctionnement des REP). Or, dans le cadre de l'augmentation des performances générales des assemblages combustibles, l'emploi d'autres matériaux, dont les propriétés de relaxation sous flux neutronique sont supérieures à celles du 718, est envisagé par AREVA. Les matériaux étudiés sont principalement des superalliages base Ni, tels que les nuances 625+ et 725 qui à l'instar de l'alliage 718 durcissent par précipitation de phases secondaires, ainsi que des nuances d'alliage 718 riche en Molybdène. Cependant, bien que ces nouveaux matériaux présentent une relaxation sous flux neutronique améliorée, ils doivent répondre également à un cahier des charges strict, propre à leur utilisation en centrale : des propriétés mécaniques équivalentes, une bonne résistance à la corrosion sous contrainte (CSC) et une bonne résistance à la fragilisation par l'hydrogène (FPH) en milieu primaire de REP. Chacune de ces propriétés a été étudiée avec attention dans le double but de comparer ces matériaux entre eux et afin de cerner les paramètres clés contrôlant leur différence de comportement aussi bien en CSC qu'en FPH / Hold-down systems used in the fuel assembly of Nuclear Pressurized Water Reactor (PWR) are constituted by stiff springs. The role of the hold-down springs is to ensure the bond between the fuel assembly and the lower plate of the intern structure of the core, thus holding down the assembly on the bottom plate of the reactor, during all the exploitation and maintenance periods. Nowadays, alloy 718 is the constitutive material of these hold-down springs. Its properties in terms of mechanical behaviour, corrosion resistance… fill in the specifications required for such application in the present service conditions. However, in order to improve the common efficiency of fuel assemblies, the upgrading of their design as well as the use of new materials are advocated by the nuclear power plant company, AREVA. Though other Ni-base superalloys known for their good behaviour under neutronic radiation can be proposed as new materials, those superalloys must fill in all the application specifications in order to substitute alloy 718. So, sufficient mechanical properties, good resistance to Stress Corrosion Cracking (SCC) and good resistance to Hydrogen Embrittlement (HE) are also required to allow the replacement. All of these properties are carefully studied with the double aim to characterize and compare different superalloys, and to determine key parameters governing the SCC and HE behaviours of such alloys in primary water of PWR