Survey propagation (SP) has recently been discovered as an efficient algorithm in solving classes of hard constraint-satisfaction problems (CSP). Powerful as it is, SP is still a heuristic algorithm, and further understanding its algorithmic nature, improving its effectiveness and extending its applicability are highly desirable. Prior to the work in this thesis, Maneva et al. introduced a Markov Random Field (MRF) formalism for k-SAT problems, on which SP may be viewed as a special case of the well-known belief propagation (BP) algorithm. This result had sometimes been interpreted to an understanding that “SP is BP” and allows a rigorous extension of SP to a “weighted” version, or a family of algorithms, for k-SAT problems. SP has also been generalized, in a non-weighted fashion, for solving non-binary CSPs. Such generalization is however presented using statistical physics language and somewhat difficult to access by more general audience. This thesis generalizes SP both in terms of its applicability to non-binary problems and in terms of introducing “weights” and extending SP to a family of algorithms. Under a generic formulation of CSPs, we first present an understanding of non-weighted SP for arbitrary CSPs in terms of “probabilistic token passing” (PTP). We then show that this probabilistic interpretation of non-weighted SP makes it naturally generalizable to a weighted version, which we call weighted PTP. Another main contribution of this thesis is a disproof of the folk belief that “SP is BP”. We show that the fact that SP is a special case of BP for k-SAT problems is rather incidental. For more general CSPs, SP and generalized SP do not reduce from BP. We also established the conditions under which generalized SP may reduce as special cases of BP. To explore the benefit of generalizing SP to a wide family and for arbitrary, particularly non-binary, problems, we devised a simple weighted PTP based algorithm for solving 3-COL problems. Experimental results, compared against an existing non-weighted SP based algorithm, reveal the potential performance gain that generalized SP may bring.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-06-30T13:08:52Z No. of bitstreams: 1 ELVIRA BEZERRA PESSOA - DISSERTAÇÃO PPGEA 2004..pdf: 25315444 bytes, checksum: 5be953c0f57dcad2cd5d4fb9e7795cdb (MD5) / Made available in DSpace on 2018-06-30T13:08:52Z (GMT). No. of bitstreams: 1 ELVIRA BEZERRA PESSOA - DISSERTAÇÃO PPGEA 2004..pdf: 25315444 bytes, checksum: 5be953c0f57dcad2cd5d4fb9e7795cdb (MD5) Previous issue date: 2004-04 / Dentre as pragas associadas às sementes e grãos armazenados no Brasil, o gorgulho, Sitophilus zeamais, destaca-se como um dos principais responsáveis na queda da produção, devido as perdas e danos provocado por este inseto praga. Com bases nessas considerações e dentro de um alinhamento ecológico, realizou-se o presente trabalho, objetivando avaliar a eficácia de sete extratos vegetais, com propriedades inseticidas, no controle do inseto na fase imatura (ovo) e a mortalidade do inseto adulto. Os extratos hidroálcoolicos foram obtidos pelo método de extração a frio por percolação. Os trabalhos foram realizados no Laboratório de Armazenamento e Processamento de Produtos Agrícolas do DEAg da UFCG e no Laboratório de Farmacotécnica (LF) do Departamento de Farmácia e Biologia do CCBS da UEPB, ambos sediados em Campina Grande, PB. Inicialmente, realizou-se a multiplicação do inseto a partir de exemplares coletados em grãos armazenados. Posteriormente, foram aplicados, pelo método do vapor, aos insetos adultos contidos em recipientes plásticos na dose estabelecida para cada tratamento (4, 8, 12 e 16 ml). Em uma segunda fase, selecionou-se os quatros melhores extratos e as duas doses que mataram os insetos adultos na primeira fase, os quais foram levados aos carunchos, previamente inoculados em uma massa de milho pipoca, pelo método do vapor e diretamente sobre as sementes, que depois de homogeneizadas eram secas a sombra por 24 horas. Em uma terceira etapa, testou-se os dois melhores extratos, aplicados diretamente sobre as sementes de milho pipoca, contendo ovos do S. zeamais, na dose de 16 ml, para a avaliação da eficácia dos mesmos sobre a emergência do inseto depois de 40 dias da instalação dos ensaios. Em um quarto experimento, avaliou-se o efeito desses mesmos extratos e dose, empregados na etapa anterior, sobre a eficácia dos mesmos no controle do S. zeamais e seus efeitos na germinação, teor de umidade e sementes infestadas. Tendo sido constatado, mediante os resultados de cada bioensaio, que os insetos adultos de Sitophilus zeamais são controlados igualmente com os extratos de Citrus cinensis (98,62%), Cymbopogon citratus (97,87%) e Nicotiana tabacum (96,50%), em todas as doses testadas e aplicadas pelo método do vapor. Os extratos de Nicotiana tabacum e Cymbopogon citratus, demonstraram ação ovicida, controlando esta fase imatura do gorgulho em 96,55 e 95,07%, respectivamente, e que a qualidade fisiológica da semente de milho pipoca não foi afetada pelos extratos, durante o período de armazenamento. / Among the pests associated with seeds and grains stored in Brazil, the weevil, Sitophilus zeamais, stands out as one of the main responsible in the fall of the production, due to the losses and damages caused by this insect pest. Based on these considerations and within an ecological alignment, the present work was carried out, aiming to evaluate the efficacy of seven plant extracts, with insecticidal properties, in the control of the insect in the immature phase (egg) and adult insect mortality. The hydroalcoholic extracts were obtained by the cold extraction method by percolation. The work was carried out at the Laboratory of Storage and Processing of Agricultural Products of the DEAg of the UFCG and in the Laboratory of Pharmacotechnics (LF) of the Department of Pharmacy and Biology of CCBS of UEPB, both based in Campina Grande, PB. Initially, the insect multiplication was performed from specimens collected in stored grains. Subsequently, they were applied by the steam method to adult insects contained in plastic containers at the dose established for each treatment (4, 8, 12 and 16 ml). In a second phase, the four best extracts were selected and the two doses that killed the adult insects in the first phase were selected, which were then fed to the weevils previously inoculated in a popcorn mass by the steam method and directly on the seeds , which after homogenates were dried in the shade for 24 hours. In a third step, the two best extracts were applied directly to the seeds of popcorn, containing eggs of S. zeamais, in the dose of 16 ml, for the evaluation of their efficacy on the emergence of the insect after 40 days of installation of the tests. In a fourth experiment, the effect of these same extracts and dose, employed in the previous stage, on the efficacy of the same in the control of S. zeamais and its effects on germination, moisture content and infested seeds were evaluated. It was observed that adult insects of Sitophilus zeamais are also controlled with extracts of Citrus cinensis (98.62%), Cymbopogon citratus (97.87%) and Nicotiana tabacum (96.50% ), at all doses tested and applied by the steam method. The extracts of Nicotiana tabacum and Cymbopogon citratus demonstrated ovicidal action, controlling this immature stage of the weevil in 96.55 and 95.07%, respectively, and that the physiological quality of the seed of popcorn corn was not affected by the extracts during the period of storage.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-10T22:37:45Z No. of bitstreams: 1 AldeniseReginaLiraDaSilva_DISSERT.pdf: 1225923 bytes, checksum: 748bfafb2fbad5c91c7505feee13a063 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-05-17T20:44:11Z (GMT) No. of bitstreams: 1 AldeniseReginaLiraDaSilva_DISSERT.pdf: 1225923 bytes, checksum: 748bfafb2fbad5c91c7505feee13a063 (MD5) / Made available in DSpace on 2016-05-17T20:44:11Z (GMT). No. of bitstreams: 1 AldeniseReginaLiraDaSilva_DISSERT.pdf: 1225923 bytes, checksum: 748bfafb2fbad5c91c7505feee13a063 (MD5) Previous issue date: 2015-08-18 / Em 1970, foi desativada a Casa de Deten??o de Natal, localizada no bairro de Petr?polis, sendo substitu?da pela Col?nia Penal ?Doutor Jo?o Chaves?, situada em um ambiente de caracter?sticas rurais, o distrito de Igap?. Por?m, o processo que levou a esse afastamento da pris?o em rela??o ao espa?o urbano de Natal havia come?ado tr?s d?cadas antes. A funda??o da Col?nia Penal ?Doutor Jo?o Chaves? no munic?pio de Maca?ba, e posteriormente, sua transfer?ncia para Igap?, no munic?pio de Natal, envolvem quest?es pol?ticas e sociais que agem sobre a defini??o do lugar que a pris?o deveria ocupar na cidade. Neste trabalho, pretendemos analisar o fen?meno do afastamento da pris?o em rela??o ao espa?o urbano da cidade de Natal, entre 1940 e 1975. Buscaremos investigar as rela??es que se estabeleciam entre a pris?o e a cidade de Natal, com base no modo como as pris?es aqui estudadas s?o enunciadas nos jornais e pensadas por seus planejadores, o que sofre interfer?ncias, entre outros fatores, das diferentes identidades espaciais contidas no territ?rio da cidade. Mas tamb?m buscaremos perceber a maneira como os sujeitos ligados ? pris?o, sobretudo os presos, interagem com o espa?o urbano. Abordaremos a pris?o enquanto institui??o planejada por parte do Estado, cujas expectativas envolvem rela??es pol?ticas locais e nacionais, mas tamb?m envolvem um projeto de como deveria ser a cidade. Contudo, este trabalho tamb?m ? uma tentativa de analisar o preso como sujeito em intera??o com a sociedade intra e extramuros, atrav?s de suas formas de adapta??o e resist?ncia ao encarceramento. / In 1970, the penal colony called Casa de Deten??o de Natal was disabled, located in the neighborhood of Petropolis, replaced by the penal colony called Col?nia Penal Doutor Jo?o Chaves, located in an environment of rural characteristics, the neighborhood of Igap?. However, this process of replacing had begun three decades earlier. The foundation of the Penal Colony "Jo?o Chaves" in the city of Maca?ba, and later its transfer to Igap?, in Natal, has political and social questions which act on the definition of the place that the prison should take in the city. In this thesis, we intend to analyze the phenomenon of the prison removal in relation to the urban space of the city of Natal, between 1940 and 1975. We will seek to investigate the relationships established between the prison and the city of Natal, based on how the prisons here are studied and set out in the newspapers and thought by its planners, it may be interfered, among other factors, in the different spatial identities contained in the city. But we also seek to understand how the subjects linked to prison, especially the prisoners, interact with the urban space. We address the prison as an institution planned by the state, whose expectations involve local and national political, but also involve a project as it should be the city. However, this study is also an attempt to analyze the prisoner as a subject in coordination with the intra and extramural society through their ways of adaptation and resistance to incarceration.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-06-06T20:55:25Z No. of bitstreams: 1 JoaoFernandoBarretoDeBrito_DISSERT.pdf: 2471954 bytes, checksum: 24ab2a4a8dc4485717beddd01e7b454f (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-06-08T20:21:34Z (GMT) No. of bitstreams: 1 JoaoFernandoBarretoDeBrito_DISSERT.pdf: 2471954 bytes, checksum: 24ab2a4a8dc4485717beddd01e7b454f (MD5) / Made available in DSpace on 2016-06-08T20:21:34Z (GMT). No. of bitstreams: 1 JoaoFernandoBarretoDeBrito_DISSERT.pdf: 2471954 bytes, checksum: 24ab2a4a8dc4485717beddd01e7b454f (MD5) Previous issue date: 2015-10-05 / No ano de 1878, na prov?ncia do Rio Grande do Norte, entre Cear?-Mirim e Extremoz, foi fundada a Col?nia Agr?cola de Sinimb?. Neste lugar chegaram a reunir-se cerca de 6.600 homens e mulheres pobres livres, fugindo da terr?vel seca de 1877, mas tamb?m motivados pela promessa de acesso aos g?neros de primeira necessidade, moradia e cuidados m?dicos, mediante trabalho, como defendiam os representantes do poder local e central. No entanto, n?o foi isso que os retirantes efetivamente encontraram, j? que as condi??es dentro do estabelecimento agr?cola chamavam aten??o pela pen?ria e viol?ncia, conforme den?ncia apresentada nos relat?rios presidenciais daquela ?poca. Este trabalho tem o objetivo de analisar os conflitos ocorridos na Col?nia Sinimb?, procurando enfatizar as tens?es e interesses dos representantes das elites locais e do governo central, relacionados ? constru??o e posterior fechamento desse espa?o, num contexto marcado pelos debates acerca do controle do trabalhador pobre livre. Assim, procuraremos demonstrar que, se por um lado, foram criados espa?os institucionalizados que visavam submeter o nacional livre a uma l?gica de trabalho pautada na disciplina do corpo, no controle do tempo e no ordenamento do espa?o, por outro n?o se pode desconsiderar as diferentes formas de resist?ncia impostas pelos homens e mulheres pobres livres, submetidos ao processo de reordenamento do mundo do trabalho. / In 1878, at the province of Rio Grande do Norte, between Cear?-Mirim and Extremoz, was founded the Agricultural Colony of Sinimb?. On this location, about 6,600 freed men and women had gathered. They were not only fleeing from the terrible 1877 drought but also encouraged by the promise of accessing basic necessities, i.e. housing and medical assistance, upon work, as required by local and central representatives of power. However, the migrants faced otherwise reality, since conditions within the agricultural facility were of shortage and violence, as denounced on the presidential reports of that time. This work aims at analyzing the conflicts that took place at the Sinimb? Colony, while it seeks to emphasize how the tensions and interests of both local elite and central government representatives relate to the opening and closure of this space, on a context where the debate on the control over freed poor workers was on the rise. Thus, we intend to demonstrate that on the one hand, institutionalized places provided the native freed a sense of work guided by the discipline of the body, control of time and arrangement of space. On the other hand, unlike forms of resistance enacted by freed working men and women undergoing the rearranging process of labor world cannot be disregarded.

Made available in DSpace on 2014-12-17T15:37:17Z (GMT). No. of bitstreams: 1 AilaSF_DISSERT.pdf: 2602874 bytes, checksum: 17786cedd4c6cf455a1bade82e0156e9 (MD5) Previous issue date: 2013-03-25 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Collembola is one of the most abundant and diverse group of terrestrial arthropods, being at the base of the food chain operating in the decomposition process. They have a wide distribution in the world and can be found in practically all habitats. The knowledge of this distinctive fauna is still deficient in brazilian territory, especially in semi-arid region. The aim of this study was to investigate which climatic variables may act as predictors of species richness, abundance of individuals and compositional structure of the taxocenose of Collembola over 12 months in an area dominated by semi-arid Caatinga vegetation, northeastern Brazil and describe new species of the genus Seira found, more diverse taxon of Collembola in Brazil. Samples were collected in Jo?o C?mara, Rio Grande do Norte. Ten plots of 20 x 20 meters were established and the specimens were collected with collection effort of one hour/people using entomological aspirator. The identification and description of the species was carried out by studying the morphology and chaetotaxy. Was performed a multiple regression analysis between species richness and abundance of individuals with climatic variables. A total of 1231 individuals belonging to 15 species, 12 genera and nine families. The greatest richness and abundance of Collembola were found during the rainy season. The genus Seira was the most abundant. Rainfall explained the temporal variation in species richness and abundance of Collembola in the semi-arid region, which is consistent with the biology of these animals. The populations of Collembola showed grouped distribution. Three new species of Seira were described and illustrated and all show similarities with species already registered in the national territory / Collembola constitui um dos grupos mais abundantes e diversos de artr?podes terrestres, estando na base da cadeia alimentar e atuando no processo de decomposi??o. Possuem ampla distribui??o no mundo e podem ser encontrados em praticamente todos os habitats. O conhecimento desta distinta fauna ainda ? deficiente em territ?rio brasileiro, especialmente no semi?rido. O objetivo desse estudo foi investigar quais as vari?veis clim?ticas podem atuar como preditoras da riqueza de esp?cies, abund?ncia de indiv?duos e da estrutura composicional da taxocenose de Collembola ao longo de 12 meses em uma ?rea semi?rido dominada por vegeta??o de Caatinga, Nordeste brasileiro; e descrever novas esp?cies encontradas do g?nero Seira, t?xon mais diverso de Collembola no Brasil. As coletas foram realizadas em Jo?o C?mara, Rio Grande do Norte. Dez parcelas de 20 x 20 metros foram estabelecidas e os esp?cimes foram coletados com esfor?o de coleta de uma hora por pessoa utilizando um aspirador entomol?gico. A identifica??o e descri??o das esp?cies foram realizadas atrav?s do estudo da morfologia e quetotaxia dos exemplares. Foi realizada uma an?lise de regress?o m?ltipla entre a riqueza de esp?cies e a abund?ncia de indiv?duos com as vari?veis clim?ticas. Foi coletado um total de 1231 indiv?duos, distribu?dos em 15 esp?cies, 12 g?neros e nove fam?lias. As maiores riqueza e abund?ncia de Collembola foram encontradas durante a esta??o chuvosa. O g?nero Seira foi o mais abundante. A precipita??o explicou varia??o temporal da riqueza de esp?cies e abund?ncia de Collembola no semi?rido, o que condiz com a biologia desses animais. As popula??es de Collembola apresentaram distribui??o agrupada. Tr?s esp?cies novas de Seira foram descritas e ilustradas e todas apresentam semelhan?as com esp?cies j? registradas em territ?rio nacional

Submitted by Programa de P?s-Gradua??o Engenharia El?trica (ppgee@ifpb.edu.br) on 2018-04-17T14:29:25Z No. of bitstreams: 1 41- Aldeni Sud?rio de Sousa - ALGORITMO BIOINSPIRADO EM COL?NIA DE ABELHAS APLICADO NA SELE??O DE CARACTER?STICAS PARA DETEC??O DE DESVIOS VOCAIS.pdf: 1351824 bytes, checksum: 09fd69be675ff9f0dc04fae3523582cf (MD5) / Approved for entry into archive by Programa de P?s-Gradua??o Engenharia El?trica (ppgee@ifpb.edu.br) on 2018-04-17T14:30:31Z (GMT) No. of bitstreams: 1 41- Aldeni Sud?rio de Sousa - ALGORITMO BIOINSPIRADO EM COL?NIA DE ABELHAS APLICADO NA SELE??O DE CARACTER?STICAS PARA DETEC??O DE DESVIOS VOCAIS.pdf: 1351824 bytes, checksum: 09fd69be675ff9f0dc04fae3523582cf (MD5) / Made available in DSpace on 2018-04-17T14:30:31Z (GMT). No. of bitstreams: 1 41- Aldeni Sud?rio de Sousa - ALGORITMO BIOINSPIRADO EM COL?NIA DE ABELHAS APLICADO NA SELE??O DE CARACTER?STICAS PARA DETEC??O DE DESVIOS VOCAIS.pdf: 1351824 bytes, checksum: 09fd69be675ff9f0dc04fae3523582cf (MD5) Previous issue date: 2018-01-31 / A sele??o de caracter?sticas ? uma etapa importante, empregada em v?rias tarefas de reconhecimento de padr?es, para identificar os atributos mais significativos e descartar aqueles irrelevantes ou redundantes pertencentes a um conjunto original. Algoritmos bioinspirados, baseados no comportamento de organismos, s?o adequados para problemas de otimiza??o e v?m sendo, recentemente, empregados para a sele??o de caracter?sticas em v?rios dom?nios de problemas. Nesta pesquisa, a vers?o bin?ria do algoritmo bioinspirado em col?nia artificial de abelhas ? aplicado na sele??o de caracter?sticas para detec??o de desvios vocais, com o intuito de determinar quais medidas ac?sticas baseadas na an?lise da quantifica??o de recorr?ncia s?o relevantes para a discrimina??o entre vozes saud?veis e vozes com desvios vocais (soprosidade, rugosidade e tens?o). Os resultados apontam que, de forma geral, houve uma redu??o na quantidade de caracter?sticas utilizadas na classifica??o, empregando-se o classificador K-NN, com taxas de acur?cia superiores a 86%, apresentando competitividade quando comparados com outras abordagens.

Recentemente, tornou-se acessível a análise filogenética com base em caracteres contínuos. Isso amplia a quantidade de caracteres que podem ser utilizados em análises filogenéticas baseadas em morfologia, mas não há ainda um consenso sobre como esse tipo de caráter deve ser codificado e analisado. Este trabalho analisa o uso de caracteres contínuos em filogenias com dois diferentes enfoques: simulações em computador e aplicação em uma análise com dados reais. As simulações realizadas indicam que de fato pode-se recuperar filogenias com base em caracteres contínuos, com alguns cuidados. O mais importante deles é o uso de pesagem implícita. Mesmo com esse cuidado, os ramos pouco suportados podem ser incorretos, provavelmente devido a um efeito de atração de ramos longos. Na análise do gênero Anchylorhynchus, utilizei caracteres discretos e contínuos, em separado e combinados. As árvores obtidas com as matrizes separadas são bastante diferentes, e a árvore da matriz combinada é semelhante àquela obtida somente com os caracteres discretos. O suporte dos ramos, contudo, cresce com a adição dos caracteres contínuos. Os caracteres contínuos, portanto, não devem ser vistos como uma alternativa, mas como um acréscimo às análises tradicionais. A revisão taxonômica de Anchylorhynchus resultou na descrição de nove espécies novas e reconhecimento de quatro sinônimos novos. O gênero resultou ser um grupo monofilético com um total de 24 espécies reconhecidas. Além disso, as informações sobre a biologia e a distribuição geográfica desses gorgulhos foi atualizada. Em conjunto com a filogenia obtida, essas informações basearam reconstruções biogeográficas e da associação histórica com as plantas hospedeiras. / Recently, phylogenetic analysis based on continuous characters was made accessible. This increases the pool of characters available for morphology-based phylogenetic analyses, but there is still no consensus on how this kind of characters should be coded and analyzed. In the present study, I assessed the use of continuous characters in phylogenies from two distinct perspectives: computer simulations and an application to real data. The simulations indicate that one can indeed recover phylogenies based on continuous characters, given some precautions. The most important of them is the use of implied weighting. Even when this is done, poorly supported branches may be incorrect, probably due to long-branch attraction. For the phylogenetic analysis of Anchylorhynchus, I used both continuous and discrete characters, separately or combined. Trees obtained with separate matrices were significantly different, and the combined matrix resulted in a tree very similar to the tree obtained with discrete characters alone. Branch supports, however, increased with the addition of continuous characters. Continuous characters, therefore, should not be considered an alternative to traditional analyses. Rather, they should be added to discrete-character matrices. The taxonomic revision of Anchylorhynchus resulted in nine new species described and four new synonyms recognized. The genus resulted to be a monophyletic group containing 24 recognized species. Moreover, the information on weevils\' biology and geographical distribution was updated. Together with the phylogeny this information embased reconstructions of host relationships and biogeography.

Toxoplasma gondii est un parasite intracellulaire obligatoire responsable de la toxoplasmose. Il appartient au phylum des Apicomplexes, qui regroupe les espèces de Plasmodium responsables de la malaria. Les Apicomplexes ont un mécanisme d’invasion unique, impliquant la formation d’une interaction étroite entre la membrane plasmique du parasite et celle de la cellule hôte, appelée « jonction mobile » (MJ). Cette jonction est composée de la protéine AMA1 exposée à la surface du parasite qui interagit avec le complexe de protéines parasitaires RON2/RON4/RON5/RON8 injecté dans la cellule hôte. Les objectifs de ma thèse ont été d’étayer la composition moléculaire de la MJ et d’étudier la contribution de la cellule hôte dans l’invasion au travers de la recherche de partenaires de l’hôte pour les RONs. Quatre protéines de l’hôte, ALIX, TSG101, CD2AP et CIN85, ont été identifiées à la MJ. Les sites d’interactions ont été cartographiés sur RON2, RON4 et RON5. Des parasites mutants déficients pour le recrutement de ces partenaires ont été générés, et ont permis de montrer l’importance de l’association d’ALIX, TSG101, CD2AP et CIN85 à la MJ pour l’invasion de T. gondii et sa virulence dans un modèle murin. Le rôle de ces protéines dans le maintien des jonctions intercellulaires mais aussi leur participation à des processus de déformation membranaire, suggère que le parasite les recrute afin de favoriser son attachement et son internalisation. Nous avons également identifié un nouveau membre du complexe de RONs, appelé RON14. RON14 n’est pas essentielle pour la survie du parasite in vitro mais contribue à sa virulence in vivo. / Toxoplasma gondii is an obligate intracellular parasite responsible for toxoplasmosis. It belongs to the phylum Apicomplexa, which include Plasmodium species responsible for malaria. Apicomplexa has developed a unique invasion mechanism, involving the formation of a tight connection between the parasite and the host cell plasma membranes called moving junction (MJ). This junction is composed of AMA1 exposed at the surface of the parasite which interacts with a complex of parasite proteins RON2/RON4/RON5/RON8 injected into the host cell. The objectives of my thesis were to decipher the molecular composition of the MJ and to study the contribution of the host cell during invasion though the search of hosts partners for RONs. Four host proteins, ALIX, TSG101, CIN85 and CD2AP, have been identified at the MJ. Binding sites has been mapped on RON2, RON4 and RON5. By generating mutant parasites deficient for host partners recruitment, we show the importance of ALIX, TSG101, CIN85 and CD2AP association at the MJ for invasion and virulence in a mouse model. The role of these proteins in maintaining the intercellular junctions and inducing membrane deformation suggest that the parasite recruits them in order to favor its attachment and its internalization. We also identified a new member of the RON complex, called RON14. RON14 is not essential for the parasite survival in vitro but contributes to its virulence in vivo.

Le potentiel invasif et métastatique d'une tumeur est contrôlé par l'angiogenèse via le VEGF (Vascular Endothelial Growth Factor) et les altérations des systèmes impliqués dans l'adhérence cellulaire via les cadhérines. Dans ce travail, nous montrons que le L-165041, agoniste du récepteur nucléaire PPARβ (Peroxisome Proliferator-Activated Receptor) régule l'expression du VEGF dans des cellules dérivées de cancer du col de l'utérus dont le facteur étiologique est un papillomavirus (HPV). Cependant, cet effet est observé uniquement dans des cellules HPV18 indépendamment de l'oncoprotéïne virale E6 et de sa cible p53. De façon intéressante, à la diflérence de ce que nous observons dans des cellules de cancer vésical, le L- 165041 ne contrôle pas la transcription mais stabilise les messagers des isoformes du VEGF (VEGF121, VEGF165, VEGF189) indépendamment du récepteur PPARβ. La stabilisation des ARNm VEGF nécessite la phosphorylation de la p38 MAPK qui conduit, seule ou suite à une cascade de phosphorylations, au déplacement de la protéine HuR du noyau vers le cytoplasme et in fine à la stabilisation des ARNm VEGF. D'autre part, l'agoniste du PPARβ interviendrait dans la« transition épithélio-mésenchymateuse » de cellules urothéliales malignes, puisqu'une augmentation de l'expression de la cadhérine E (marqueur épithélial) et une diminution de l'expression de la cadhérine N (marqueur mésenchymateux) sont observées selon le phénotype cellulaire. Elucider le mécanisme moléculaire d'action des agonistes de PPARβ est d'un intérêt crucial puisque certains ligands sont en cours d'évaluation clinique pour le traitement de maladies métaboliques (dyslipidémies diabète de tvpe II). / Tumor invasive and metastatic potential is controlled by angiogenesis through VEGF (Vascular Endothelial Growth Factor) up-regulation and altered cadherin-mediated cellular adhesion as well. In this work, we show that the L-165041 nuclear receptor PPARβ (Peroxisome Proliferator-Activated Receptor) agonist regulates VEGF expression in cervical cancer derived cells harboring a Human Papilloma Virus (HPV). However, this effect is only observed in HPVl8 positive cells through E6 viral oncoprotein and p53 independent mechanisms. Interestingly, unlike our data obtained in bladder cancer cells, L-165041 does not control VEGF transcription but stabilizes VEGF isoforms mRNA (VEGF121, VEGFl65, VEGFl89) and acts through PPARβ-independent mechanisms. This mRNA stabilization requires p38 MAPK phosphorylation leading to the nuclear/cytoplasmic shuttling ofHuR protein and consequently to the VEGF mRNA stabilization. Furthennore, the PPARβ agonist would be involved in epithelial to mesenchymal transition since it increases E-cadherin expression and decreases N-cadherin one according to the cellular phenotype. To elucidate the molecular mechanism of PPARβ agonists action is crucial because some of ligands are currently in clinical trials for the treatment of metabolic diseases (dyslipidemia, type II diabetes).

Survey propagation (SP) has recently been discovered as an efficient algorithm in solving classes of hard constraint-satisfaction problems (CSP). Powerful as it is, SP is still a heuristic algorithm, and further understanding its algorithmic nature, improving its effectiveness and extending its applicability are highly desirable. Prior to the work in this thesis, Maneva et al. introduced a Markov Random Field (MRF) formalism for k-SAT problems, on which SP may be viewed as a special case of the well-known belief propagation (BP) algorithm. This result had sometimes been interpreted to an understanding that “SP is BP” and allows a rigorous extension of SP to a “weighted” version, or a family of algorithms, for k-SAT problems. SP has also been generalized, in a non-weighted fashion, for solving non-binary CSPs. Such generalization is however presented using statistical physics language and somewhat difficult to access by more general audience. This thesis generalizes SP both in terms of its applicability to non-binary problems and in terms of introducing “weights” and extending SP to a family of algorithms. Under a generic formulation of CSPs, we first present an understanding of non-weighted SP for arbitrary CSPs in terms of “probabilistic token passing” (PTP). We then show that this probabilistic interpretation of non-weighted SP makes it naturally generalizable to a weighted version, which we call weighted PTP. Another main contribution of this thesis is a disproof of the folk belief that “SP is BP”. We show that the fact that SP is a special case of BP for k-SAT problems is rather incidental. For more general CSPs, SP and generalized SP do not reduce from BP. We also established the conditions under which generalized SP may reduce as special cases of BP. To explore the benefit of generalizing SP to a wide family and for arbitrary, particularly non-binary, problems, we devised a simple weighted PTP based algorithm for solving 3-COL problems. Experimental results, compared against an existing non-weighted SP based algorithm, reveal the potential performance gain that generalized SP may bring.