Cette thèse se compose de trois parties. La première partie est consacrée aux partitions planes cylindriques, la deuxième aux lambda-déterminants et enfin la troisième aux commutateurs dans les systèmes semi-circulaires. La classe des partitions planes cylindriques est une généralisation naturelle de celle des partitions planes inverses. Borodin a donnée récemment une série génératrice pour les partitions planes cylindriques. Notre premier résultat est une preuve bijective de cette identité utilisant les diagrammes de croissance de Fomin for la correspondance RSK généralisée. Le deuxième résultat est un (q, t)-analogue de la formule de Borodin, qui généralise un résultat d'Okada. Enfin le troisième résultat de la première partie est une description combinatoire explicite du poids de Macdonald intervenant dans cette formule, qui utilise un modèle de chemins non-intersectant pour les partitions planes cylindriques. Les matrices à signes alternants ont ́été découvertes par Robbins et Rumsey alors qu’ils étudiaient les λ-déterminants. Dans la deuxième partie de cette thèse nous démontrons une généralisation à plusieurs paramètres de ce λ-déterminant, généralisant un résultat récent de di Francesco. Comme le λ-déterminant, notre formule est un exemple du phénomène de Laurent. Les systèmes semi-circulaires ont ́été introduits par Voiculescu afin d' ́étudier les algèbres de von Neumann des groupes libres. Dans la troisième partie de la thèse, nous étudions les commutateurs dans l'algèbre engendré par un système semi-circulaire. Nous avons mis en ́évidence une matrice possédant une structure auto-similaire intéressante, qui nous permet de donner une formule explicite pour la projection sur l'espace des commutateurs de degré donnée. En utilisant cette expression, nous donnons une preuve simple du fait que les systèmes semi-circulaires engendrent des facteurs / This thesis is divided into three parts. The first part deals with cylindric plane partitions. The second with lambda-determinants and the third with commutators in semi-circular systems. Cylindric plane partitions may be thought of as a natural generalization of reverse plane partitions. A generating series for the enumeration of cylindric plane partitions was recently given by Borodin. The first result of section one is a new bijective proof of Borodin's identity which makes use of Fomin's growth diagram framework for generalized RSK correspondences. The second result is a (q, t)-analog of Borodin's identity which extends previous work by Okada in the reverse plane partition case. The third result is an explicit combinatorial interpretation of the Macdonald weight occuring in the(q, t)-analog using the non-intersecting lattice path model for cylindric plane partitions. Alternating sign matrices were discovered by Robbins and Rumsey whilst studying λ-determinants. In the second part of this thesis we prove a multi-parameter generalization of the λ-determinant, generalizing a recent result by di Francesco. Like the original λ-determinant, our formula exhibits the Laurent phenomenon. Semicircular systems were first introduced by Voiculescu as a part of his study of von Neumann algebras. In the third part of this thesis we study certain commutator sub algebras of the semicircular system. We find a projection matrix with an interesting self-similar structure. Making use of our projection formula we given an alternative, elementary proof that the semicircular system is a factor

Fundamentado na inter-relação dos sistemas naturais, sociais e culturais, esse estudo procurou compreender como se organiza a pesca da manjuba (Anchoviella lepidentostole) em Iguape/ SP, as dinâmicas de apropriação dos espaços produtivos e os conhecimentos envolvidos na prática dessa atividade. Do mesmo modo, objetivou compreender quais os fundamentos que viabilizam o uso compartilhado dos recursos pesqueiros. A partir dessas concepções foram descritas as lógicas comunitárias que permeiam as formas de acesso e exercem a manutenção e a gestão desses espaços.Os contornos do trabalho foram delimitados pelos conhecimentos tradicionais dos pescadores, que, fomentaram, juntamente com as inclinações teóricas utilizadas, o diálogo com o conhecimento cientifico. Buscou-se, dessa forma, valorizar a articulação dos saberes, a interação entre Sociedade e Natureza a fim de colaborar com as discussões contemporâneas sobre o manejo dos recursos naturais. / Based on the ecological, social and cultural interaction, this work has searched for the understanding of Manjuba fishing organization (Anchoviella lepidentostole) in the city of Iguape, (São Paulo Brazil), the dynamic of productive marine space appropriation and the knowledge involved in this practice. At the same time, looked for a comprehension of the fishing resource sharing fundamentals. These concepts were the foundation to the description of the local rules for management that are used by artisanal fishers, and for aspects of territoriality. This work borders were limited by the traditional fishers knowledge, that, together with the theory inclinations foment the scientific knowledge dialog. The final objective was demonstrating the interaction value of the human and nature, include the importance in using local rules for natural fishing resources management.

Fundamentado na inter-relação dos sistemas naturais, sociais e culturais, esse estudo procurou compreender como se organiza a pesca da manjuba (Anchoviella lepidentostole) em Iguape/ SP, as dinâmicas de apropriação dos espaços produtivos e os conhecimentos envolvidos na prática dessa atividade. Do mesmo modo, objetivou compreender quais os fundamentos que viabilizam o uso compartilhado dos recursos pesqueiros. A partir dessas concepções foram descritas as lógicas comunitárias que permeiam as formas de acesso e exercem a manutenção e a gestão desses espaços.Os contornos do trabalho foram delimitados pelos conhecimentos tradicionais dos pescadores, que, fomentaram, juntamente com as inclinações teóricas utilizadas, o diálogo com o conhecimento cientifico. Buscou-se, dessa forma, valorizar a articulação dos saberes, a interação entre Sociedade e Natureza a fim de colaborar com as discussões contemporâneas sobre o manejo dos recursos naturais. / Based on the ecological, social and cultural interaction, this work has searched for the understanding of Manjuba fishing organization (Anchoviella lepidentostole) in the city of Iguape, (São Paulo Brazil), the dynamic of productive marine space appropriation and the knowledge involved in this practice. At the same time, looked for a comprehension of the fishing resource sharing fundamentals. These concepts were the foundation to the description of the local rules for management that are used by artisanal fishers, and for aspects of territoriality. This work borders were limited by the traditional fishers knowledge, that, together with the theory inclinations foment the scientific knowledge dialog. The final objective was demonstrating the interaction value of the human and nature, include the importance in using local rules for natural fishing resources management.

Why do communal conflicts turn violent in some regions but not in others? Communal conflicts pose a severe threat to human security and kill thousands of people each year, but our understanding of this phenomenon is still limited. In particular, we lack knowledge about why some of these conflicts become violent while others are resolved peacefully. This study addresses this knowledge gap and has a novel approach by addressing subnational variations that are unexplained by previous research. The theoretical framework combines insights from three different perspectives focusing on the role of the state, elite interactions, and conditions for cooperation over common resources. Empirically, the research question is investigated by combining within- and between-region analyses of three Sudanese regions: Darfur, Eastern Sudan, and Greater Upper Nile. Despite sharing several similar characteristics, communal conflicts have killed thousands in Darfur and Greater Upper Nile but only a few dozen in Eastern Sudan. The empirical analysis builds on extensive material collected during fieldwork. This study generates several conclusions about the importance of government conduct and how state behavior contributes to the prevalence of violent communal conflicts. It finds that when governments act in a biased manner – favoring certain communities over others – interactions between central and local elites as well as among local elites are disrupted. Unconstructive elite interactions, in turn, have negative effects on three mechanisms that are crucial for communal cooperation. First, when the regime is biased, communal affiliation, rather than the severity and context of a violation, determines the sanctions that are imposed on the perpetrators. Second, government bias leads to unclear boundaries, which contribute to violent communal conflicts by creating disarray and by shifting power balances between the communities. Third, regime partiality distances rules from local conditions and restricts the influence of local actors who have an understanding of local circumstances. The study also reveals why a regime acts with partiality in some areas but not in others. The answer to this question is found in the complex interplay between the threats and opportunities that a region presents to the regime. Taken together, the findings have important implications for the prevention and management of communal conflict.