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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
421

Phenomenology of neutrino properties, unification, and Higgs couplings beyond the Standard Model

Riad, Stella January 2017 (has links)
The vast majority of experiments in particle physics can be described by the Standard Model of particle physics (SM). However, there are indications for physics beyond it. The only experimentally demonstrated problem of the model is the difficulty to describe neutrino masses and leptonic mixing. There is a plethora of models that try to describe these phenomena and this thesis investigates several possibilities for new models, both full theories and effective frameworks.   The values of the parameters in a model are dependent on the energy scale and we say that the parameters run. The exact behavior of the running depends on the model and it provides a signature of the model. For a model defined at high energies it is necessary to run the parameters down to the electroweak scale in order to perform a comparison to the known values of observed quantities. In this thesis, we discuss renormalization group running in the context of extra dimensions and we provide an upper limit on the cutoff scale. We perform renormalization group running in two versions of a non-supersymmetric SO(10) model and we show that the SM parameters can be accommodated in both versions. In addition, we perform the running for the gauge couplings in a large set of radiative neutrino mass models and conclude that unification is possible in some of them.   The Higgs boson provides new possibilities to study physics beyond the SM. Its properties have to be tested with extremely high precision before it could be established whether the particle is truly the SM Higgs boson or not. In this thesis, we perform Bayesian parameter inference and model comparison. For models where the magnitude of the Higgs couplings is varied, we show that the SM is favored in comparison to all other models. Furthermore, we discuss lepton flavor violating processes in the context of the Zee model. We find that these can be sizeable and close to the experimental limits. / <p>QC 20170221</p>
422

An Analysis of the Physical and Cultural Landscape of Grand Isle, Louisiana

Thomas, Alexis 13 May 2016 (has links)
The town of Grand Isle, Louisiana, and its rich geographic history, can offer insight into the early history of the State of Louisiana and the establishment of the United States as a country, as well as the study of the formation of barrier islands and methods of land use with such areas. The following thesis presents a geographic, as well as a historical, analysis of Grand Isle’s history. It attempts to answer the following questions: What is the shape, form, and origin of the physical landscape of Grand Isle? How have humans interacted with the land and surrounding areas of Grand Isle? And what impacts, if any, have these interactions had on the island and its landscape? These questions include research into both the built environment and the natural environment.
423

Morphodynamique de la zone de "swash" : étude en canal à houle par une méthode de stéréoscopie optique / Swash zone morphodynamics : wave flume investigation by an optical stereoscopic method

Astier, Jessica 28 April 2014 (has links)
Ce travail porte sur l’étude de l’évolution morphologique dans la zone de swash à haute résolution spatiale et temporelle afin de pouvoir analyser l’influence de la houle. Cette étude s’appuie sur deux campagnes de mesures menées dans le grand canal à houle CIEM (Barcelone), l’une avec application d’un forçage aléatoire érosif de type JONSWAP et l’autre avec application d’une série de forçages bichromatiques. L’originalité de l’étude proposée ici consiste en l’analyse, par une méthode de stéréoscopie optique, de l’évolution du fond avec une excellente précision tout en quantifiant précisément l’évolution des fronts d’eau sur une surface continue, la majorité des techniques de mesure ne donnant en général accès qu’à des relevés ponctuels dans cette zone. La position du lit de sable est estimée avec une précision de quelques centaines de μm. Sur des temps longs, le forçage JONSWAP érosif engendre un recul global et quasi-homogène dans la zone de swash. Cependant, cette évolution ne semble pas influencer la réponse hydrodynamique qui reste similaire dans la zone de swash lorsque l’on répète la série. Ceci a été confirmé dans le cas des forçages bichromatiques, répétés sur des fonds différents. Au sein d’une série d’un forçage aléatoire, différentes échelles de temps sont observées : l’échelle gravitaire (période caractéristique du signal) et les ondes infragravitaires (large gamme d’événements plus longs). Cette coexistence de plusieurs échelles de temps a pu être associée à la forte variabilité du profil de plage, notamment dans la direction cross-shore. Le cas bichromatique montre quant à lui une convergence du profil de plage vers un état qui ne dépendrait que du forçage en entrée. L’interaction d’une seule onde infragravitaire avec l’onde gravitaire ne peut donc pas être responsable de la variabilité du fond observée avec le forçage aléatoire. En revanche, cette étude semble confirmer la présence d’événements particuliers à l’origine d’une forte modification du fond sableux. Le lien entre ces événements et l’interaction entre des événements hydrodynamiques spécifiques et la forme du fond n’est pas encore complètement établi. Enfin, pour le forçage aléatoire la variabilité transverse induite par les ondes courtes est forte alors qu’elle semble plus faible à l’échelle de l’onde longue. Pour le forçage bichromatique, cette variabilité transverse a également pu être observée mais son lien avec le forçage reste encore à élucider. / This study investigates the morphological evolution in the swash zone at high spatial and temporal resolution to be able to analyze the swell influence. The study is here based on two measurement campaigns in the large CIEM wave flume (Barcelona), using both a random erosive JONSWAP and bichromatics forcing. The originality of the proposed study lies on analysis, by an optical stereoscopic method, of bottom evolution with a very good precision while getting an accurate quantification of water fronts evolution on a continuous area, most of the measurement techniques generally allowing only to obtain punctual measurements in this area. The sand bed position is estimated with an accuracy of a few hundred μm. Over long periods, erosive JONSWAP forcing generates an overall and almost homogeneous backward movement in the swash area. However, this trend does not appear to influence the hydrodynamics response that remains similar in the swash area when the series is repeated. This was confirmed in the bichromatic forcings case, repeated on different bottoms. During a random forcing series, different time scales are observed : the gravity scale (characteristic period of the signal) and infragravity waves (wide range of longer events). This coexistence of several time scales could be associated with the observation of a strong variability of the beach profile, especially in the cross-shore direction. The bichromatic case shows meanwhile convergence of beach profile to a state that would depend only on forcing conditions. The interaction of a single infragravity wave with the gravitational wave can therefore not be responsible for the observed bottom variability with the random forcing. In contrast, the present study seems to confirm the presence of specific events responsible of a strong change in the sandy bottom. The link between these events and the hydrodynamic interaction between specific events and the bottom shape is not yet completely established. Finally, for the random forcing the transverse variability induced by short wave is strong as it seems weak at long wave time scale. For bichromatic forcing, the transverse variability has also been observed but its link with the forcing still remains to be elucidated.
424

Facteurs de contrôle extrinsèques des dépôts microbiens récents en domaine de transition continental-marin / External controlling factors of modern microbial deposits at the transition between continental and marine environments

Bouton, Anthony 13 May 2016 (has links)
Les microbialites, dépôts lithifiés d’origine microbienne, sont des structures organosédimentaires documentées depuis plus de 3,5 milliards d’années. La compréhension de ces structures, des conditions et des modalités de leur mise en place, nous apporte des informations précieuses sur l’origine de la vie sur Terre. Cette thématique de recherche est également en plein essor du fait de ses implications économiques majeures concernant les hydrocarbures. La reconstitution des environnements associés aux structures microbiennes fossiles reste incertaine, notamment entre milieux de dépôts marins ou continentaux. Ces deux environnements contrastés ont été étudiés à travers deux exemples modernes, Cayo Coco (Cuba) en domaine marin lagunaire et le Grand Lac Salé (Utah, USA) en domaine lacustre continental dans le but d’identifier des critères diagnostiques pour discriminer ces environnements dans le registre fossile.La formation des microbialites résulte de la minéralisation et de la lithification d’un tapis microbien sous l’influence d’une composante métabolique (intrinsèque) liée à l’activité du tapis microbien, et d’une composante environnementale (extrinsèque). L’objectif de ce travail était de replacer à différentes échelles les dépôts microbiens dans leur contexte environnemental et de comprendre les influences directes des paramètres extrinsèques sur : (1) les processus de minéralisation des tapis microbiens et la formation de microbialites, (2) la morphologie des structures microbiennes, (3) la distribution spatio-temporelle des microbialites et des sédiments associés, et enfin (4) les relations entre les tapis microbiens et microbialites et leur environnement. / Lithified microbial deposits, considered as microbialites, are organosedimentary structures observed since 3.5 billion years. Understanding the mechanisms and environmental conditions leading to their formation may provide valuable information about the origin of life on Earth. Our interest on this research topic has increased owing to the economic implications of these deposits, especially concerning the hydrocarbons. The reconstruction of the environments associated with microbial structures remains uncertain in the fossil record, especially between marine and continental domains. These two contrasting environments were studied through two modern examples: (1) a marine-fed lagoon area in Cayo Coco (Cuba), and the continental lake of the Great Salt Lake (Utah, USA) in order to identify diagnostic criteria allowing to distinguish both environments in the fossil record.Microbialite result from mineralization and lithification of microbial mats under the influence of metabolic chemical reactions (intrinsic) related to the activity of the microbial biomass and environmental (extrinsic) conditions. The objective of this PhD is to replace microbial deposits, at different scales, in their context of formation to highlight the significance of extrinsic parameters on: (1) the mineralization processes and the formation of microbialites, (2) the morphologies of observed microbial structures, (3) their spatial distribution, and (4) the relationship between microbial mats and microbialite and their environment.
425

Large-scale acoustic and prosodic investigations of french / Analyses acoustiques et prosodiques du français à partir de grandes masses de données orales

Nemoto, Rena 16 November 2011 (has links)
Cette thèse porte sur des analyses acoustiques et prosodiques du français à partir de grandes masses de données orales illustrant différents styles de parole (préparée et spontanée). Nous nous sommes intéressées aux attributs acoustiques et prosodiques qui pourraient caractériser la prononciation. En français, de nombreuses erreurs de reconnaissance automatique de la parole (RAP) sont dues à des mots fréquents homophones. Pour ces mots, la solution correcte dépend du modèle de langage. Une classification automatique (CA) a été effectuée pour discriminer deux paires homophones (‘et/est’ et ‘à/a’) par des propriétés acoustiques et prosodiques. Les résultats de la CA ont montré que le paire ‘et/est’ était plus dissociable. La CA par des attributs prosodiques et inter-segmentaux (15 attributs) s’est avérée aussi performante que celle utilisant la totalité des 62 attributs. Un test perceptif a été également effectué pour vérifier si les humains utilisaient eux aussi ces paramètres. Les résultats ont suggéré que des informations acoustiques et prosodiques pourraient être utiles pour effectuer un choix correct de mots dans des structures syntaxiquement ambigües. Ensuite, nous avons examiné des propriétés prosodiques globales aux niveaux du nom et du syntagme nominal. La comparaison entre mots lexicaux et grammaticaux a montré que la fréquence fondamentale (F0) montante et l’allongement vocalique de la dernière syllabe caractérisent les mots lexicaux, par opposition aux mots grammaticaux. Ainsi, le profil de F0 moyenne d’un syntagme nominal de longueur n pourrait être différent de celui du nom avec une valeur de F0 basse au début du syntagme. Les profils prosodiques peuvent être utiles pour localiser frontières de mots. Les résultats de ce travail pourront servir à localiser le focus et les entités-nommées par des classifieurs discriminants, et de manière plus générale à améliorer les techniques de localisation des frontières des mots pour la RAP. / This thesis focuses on acoustic and prosodic (fundamental frequency (F0), duration, intensity) analyses of French from large-scale audio corpora portraying different speaking styles: prepared and spontaneous speech. We are interested in particularities of segmental phonetics and prosody that may characterize pronunciation. In French, many errors caused by automatic speech recognition (ASR) systems arise from frequent homophone words, for which ASR systems depend on language model weights. Automatic classification (AC) was conducted to discriminate homophones by only acoustic and prosodic properties depending on their part-of-speech function or their position within prosodic words. Results from AC of two homophone pairs, et/est (and/is) and à/a (ton/has), revealed that the et/est pair was more discriminable. A selection of prosodic and inter-phoneme attributes, that is 15 attributes, performed as good results as with 62 attributes. Then corresponding perceptual tests have been conducted to verify if humans also use acoustico-prosodic parameters for the discrimination. Results suggested that acoustic and prosodic information might help in operating the correct choice in similar ambiguous syntactic structures. From the hypothesis that pronunciation variants were due to varying prosodic constraints, we examined overall prosodic properties of French on a lexical and phrase level. The comparison between lexical and grammatical words revealed F0 rise and lengthening at the end of final syllable on lexical words, while these phenomena were not observed for grammatical words. Analyses also revealed that the mean profile of a n length noun phrase could be different from that of a n length noun with a low F0 at the beginning of a noun phrase. The prosodic profiles can be helpful to locate word boundaries. Findings in this thesis will lead to localize focus and named-entity using discriminative classifiers, and to improve word boundary locations by an ASR post-processing step.
426

Recherche de gluons scalaires avec le détecteur ATLAS auprès du LHC / Search for scalar gluons with the ATLAS detector at the LHC

Renaud, Adrien 30 November 2012 (has links)
Cette thèse décrit la recherche de nouvelles particules scalaires octets de couleur dans les données de l'expérience ATLAS auprès du Grand Collisionneur de Hadrons (LHC). Pour une large gamme de masse, la désintégration de ces scalaires en deux partons du MS domine. Cela motive la recherche de ces nouveaux scalaires dans des états finaux multijet, où ils se signaleraient comme des résonances dijet. Comme les nouveaux scalaires sont produits par paires, un état final contenant au moins quatre jets est utilisé comme environnement de recherche. Une méthode est développée pour extraire une possible résonance multijet scalaire du grand fond QCD et est utilisée pour chercher de tels scalaires dans les données de l'expérience ATLAS collectées en 2010 et 2011. Les données sont en accord avec l'estimation du fond et des limites sont posées sur la section efficace de production des scalaires en fonction de leur masse. En interprétant ces limites dans des modèles de supersymétrie, le gluon scalaire du MRSSM et du modèle hybride N=1/N=2 est exclu à 95 % CL entre 100 et 287 GeV. Les limites sont aussi interprétées dans un modèle de symétrie de jauge à la QCD, où le sgluon est remplacé par l'hyperpion qui est exclu dans une gamme de masse légèrement plus restreinte de part sa section efficace plus faible. / This thesis describes the search for new color-octet scalar particles in the ATLAS experiment data at the Large Hadron Collider (LHC). For a wide range of mass, the decay of the scalar to two SM partons dominates. This motivates the search for these new scalars in multijet final states, where they would manifest as dijet resonances. As the new scalars are products in pairs, a final state containing at least four jets is used as a search environment. A method is developed to extract a possible scalar resonance from the multijet QCD background and is used to search for such scalar in the data from the ATLAS experiment collected in 2010 and 2011. The data are in agreement with the estimation of the background and limits are set on the scalar production cross section as a function of the scalar mass. Interpreting these limits in models of supersymmetry, the scalar gluon of the MRSSM and of the hybrid N=1/N=2 model is excluded at the 95 % CL between 100 and 287 GeV. Limits are also interpreted in a model of gauge symmetry à la QCD, where the sgluon is replaced by the hyperpion excluded in a mass range slightly smaller because of its smaller cross section.
427

Luciano di Samosata e la civiltà ellenistica : imitazione e “ri-creazione / Lucien de Samosate et la civilisation hellénistique : imitation et "ré-création" / Lucian of Samosata and the Hellenistic civilisation : imitation and "re-creation"

Marcinnò, Micol 07 April 2017 (has links)
Comme le titre le suggère, la thèse s’inspire du "Lucien écrivain. Imitation et création de Jacques Bompaire". Dans l’introduction nous reparcourons l’histoire de l’Hellenismus de Droysen et nous surlignons le poids du mélange culturel gréco-oriental dans la vie et dans l’œuvre de Lucien. Le premier chapitre consiste en un corpus commenté de passages lucianesques contenant des éléments hellénistiques évidents. Dans le deuxième chapitre nous analysons plusieurs aspects de la civilisation hellénistique présents dans l’œuvre de Lucien comme la politique, l’art, le mythe, les programmes littéraires. Dans le troisième chapitre nous étudions l’influence de la poésie alexandrine dans l’œuvre de l’A., alors que le quatrième chapitre analyse l’influence que des formes littéraires relevant d’un substrat culturel de sagesse populaire ont eue sur l’A. L’approche textuelle et philologique adoptée permet d’affirmer que Lucien connaissait la civilisation hellénistique et sa littérature. / As the title suggests, the thesis takes inspiration from Jacques Bompaire’s Lucien écrivain. Imitation et creation. In the introduction we retrace the history of Droysen’s Hellenismus and we detect the importance of the greco-oriental cultural fusion in Lucian’s life and works. The first chapter consists of a commented corpus of lucianic passages containing evident hellenistic elements. In the second chapter we analyse different aspects of the hellenistic civilisation which are detectable in Lucian’s works such as politics, arts, myth or literary programs. In the third chapter we compare Lucian’s literary production with Alexandrian poetry, while the forth chapter focuses on the literary influence that hellenistic philosophical and historiographical productions had on Lucian’s composition. This research makes it possible to state that the author of Samosata had a deep knowledge of hellenistic civilisation and that hellenistic literature influenced his way of writing.
428

Etude de la réalisation d'une structure transistor (FET) pour l'observation de l'exciton du ZnO sous champ électrique. / Study of the realization of a FET transistor structure for ZnO exciton observation under electric field

Maertens, Alban 13 October 2016 (has links)
Ce manuscrit porte sur la conception d’un transistor à effet de champ destiné à l’observation de la photoluminescence de l’exciton et des complexes excitoniques chargés du ZnO sous l’influence d’un champ électrique. Pour cela, des simulations ont permis de définir un cahier des charges de la structure du transistor afin de bloquer la conductivité dans le canal de ZnO et d’appliquer un champ électrique intense. La seconde partie concerne le choix du matériau de grille et de l’électrode transparente de surface pour l’observation de la photoluminescence dans le canal. L’oxyde de gallium (-Ga2O3) a été choisi car il présente un grand gap, des propriétés d’isolant et de semi-conducteur avec dopage. Cependant les films de Ga2O3 dopés avec Ti, Sn, Zn et Mg élaborés par MOCVD n’ont pas révélé de conductivité. Les films d’alliages (Ga,Sn)2O3 n’ont pas non plus montré de conductivité et leur structure est étudiée intensivement. Des traitements plasma radiofréquence sous flux d’argon, d’oxygène ou d’hydrogène ont permis de montrer que l’implantation de l’hydrogène donne lieu à un niveau donneur avec une énergie d’activation de 7 meV. La conductivité est toutefois modulée par le dopage en Sn et les traitements s’accompagnent d’un changement de la sous-stœchiométrie en oxygène qui diminue la transparence à cause de la formation de niveau profond de lacune d’oxygène. La structure finale de la grille transparente dans l’ultraviolet pour l’observation de la photoluminescence du ZnO peut donc être élaborée par une grille diélectrique de -Ga2O3 puis une électrode conductrice transparente de (Ga,Sn)2O3 traitée superficiellement par un plasma d’hydrogène. / This manuscript covers the design of a field transistor for the observation of photoluminescence of the exciton and the charged excitonic complex of ZnO under the influence of an electric field. For this, simulations have helped to define the specifications of the transistor structure to block the conductivity in the ZnO channel and applying a strong electric field. The second part concerns the choice of gate material and the surface transparent electrode for the observation of photoluminescence in the channel. The gallium oxide (-Ga2O3) was chosen because it has a large gap, insulating properties and semiconductor properties with doping. However, Ga2O3 films doped with Ti, Sn, Zn and Mg MOCVD did not show conductivity. Films of alloys (Ga,Sn)2O3 have not shown either conductivity and their structure is studied intensively. Radio frequency plasma treatment under a flux of argon, oxygen or hydrogen have shown that implantation of hydrogen gives rise to a donor level with 7 meV activation energy. However, the conductivity is modulated by doping Sn and treatments are accompanied by a change of sub-stoichiometry in oxygen, which reduces the transparency due to the formation of deep level of oxygen vacancy. The final structure of the transparent gate in the ultraviolet for the observation of photoluminescence of ZnO can be prepared by a dielectric gate -Ga2O3 and a transparent conductive electrode of (Ga,Sn)2O3 surface treated by a plasma of hydrogen.
429

The police reform process in Kenya, 2008-2014 : a case study of security sector reform in societies emerging from crisis

Ondoro, Nicholas Otieno January 2015 (has links)
Security sector reform has in the recent past been a critical component of peace agreements in countries emerging from armed conflicts or political crisis. In Kenya, the Commission of Inquiry into the 2007/08 Post-Election Violence (CIPEV) established that Kenya’s security sector, particularly the police, bore the greatest responsibility for the violence. Subsequently, the police emerged as one of the major institutions for reforms. ‘How have security sector reforms, particularly police reforms, in Kenya developed since 2007 and how, and to what extent, have they been shaped by Kenya’s wider political transitions and SSR process during this period?’ The research aimed at investigating how the police reform process in Kenya has developed since 2007, and how the process has been shaped by Kenya’s wider political transitions and security sector reform processes in general. Using mixed methods research, we found that despite some progress, there is wider public perception that the reforms are yet to address reform priorities at the national level and still fall short of expectations of ordinary Kenyans. We argue that political power-sharing after the 2007 post-election violence facilitated police reform, while at the same time frustrated its implementation especially in instances where reform seemed to dis-empower political elites.
430

Cooperative security strategy in the South Atlantic : United States internal determinants and region ressignification

Machado, Luís Rodrigo January 2017 (has links)
Esta dissertação tem como objetivo central discutir a importância do Atlântico Sul para os Estados Unidos da América, a partir da análise das suas políticas de segurança cooperativa para a parcela sul do Oceano Atlântico considerando, principalmente, seus determinantes internos e a própria ressignificação da região entre os anos de 2003 e 2014. Ela se enquadra nas Resoluções nº 114/2014 e 115/2014 da Câmara de Pós-Graduação da UFRGS e, portanto, é dividida em três capítulos, correspondendo a três partes distintas. O Primeiro Capítulo é desenvolvido em três etapas: Primeiro, relaciona o contexto da dissertação na linha de pesquisa “Segurança Internacional” do PPGEEI/UFRGS. Segundo, aborda alguns elementos das políticas externa e de segurança dos EUA, a importância do mar para a condução dessas políticas e uma breve contextualização do Atlântico Sul. Terceiro, ressalta os principais pontos analíticos e considerações desenvolvidos no capítulo seguinte. O Segundo Capítulo traz o artigo publicado na Revista da Escola de Guerra Naval que conduz, primeiro, uma breve discussão de alguns conceitos teóricos importantes para entender a postura dos Estados Unidos na condução de sua política externa e de segurança, recorrendo ao debate da influência da política interna nas suas relações internacionais. Em seguida, discute brevemente a importância do "uso do mar" para a política externa dos EUA, contextualizando o Atlântico Sul como uma região estratégica, discutindo suas fronteiras geográficas, aspectos econômicos e organizações multilaterais. Finalmente, discute alguns dos programas norte-americanos de segurança cooperativa para o Atlântico Sul e a crescente importância da região, em linha com o novo posicionamento estratégico pós-11 de setembro. O Capitulo três faz uma breve análise dos resultados do artigo e também apresenta agendas de pesquisas possíveis de serem conduzias no PPGEEI. Foi verificada a importância do artigo para trazer a discussão da segurança cooperativa, pelo viés estadunidense, no âmbito da pesquisa no PPG e também para fomentar a visibilidade deste problema nos fóruns de discussão e leitores do periódico científico de sua publicação. Assim,foram cumpridos os objetivos de discutir a importância do Atlântico Sul para os Estados Unidos da América, a partir da discussão das políticas de segurança cooperativa, dos determinantes políticos internos e da mudança da relevância da região para a grande estratégia norte-americana. Inferindo então, a pertinência do Atlântico Sul, evidenciada pela busca de iniciativas de segurança colaborativa e combate às ameaças de baixa intensidade, visando conter novas ameaças e enfrentar atores não estatais. / The present dissertation aims to discuss the importance of the South Atlantic to the United States of America, from the analysis of its cooperative security policies for the southern part of the Atlantic Ocean, considering mainly its internal determinants and the re-signification of the region between the years of 2003 and 2014. It is in accordance with Resolutions 114/2014 and 115/2014 of the Universidade Federal do Rio Grande do Sul, and therefore comprises three chapters, corresponding to three distinct parts. Chapter One presents three steps: First, it relates the context of the dissertation in the research line "International Security" of the Post-Graduate Program in International Strategic Studies. Second, it addresses some elements of the U.S. foreign and security policy, the importance of the sea for the conduct of these policies and a brief contextualization of the South Atlantic. Third, it highlights the main analytical points and considerations that developed in the next chapter. Chapter Two brings the article published in the Revista da Escola de Guerra Naval which leads, firstly to, a brief discussion of some important theoretical concepts to understand the U.S. position in the conduct of its foreign and security policy, using the debate of the U.S. internal policy on their international relations. Then, briefly discusses the importance of "use of the sea" for U.S. foreign policy, contextualizing the South Atlantic as a strategic region, discussing its geographical boundaries, economic aspects, and multilateral organizations. Finally, discuss some North American cooperative security programs for the South Atlantic and the region's growing importance, in line with the new strategic post-9/11 position. Chapter Three brings a brief analysis of the paper's impacts and presents possibilities of investigation agendas to follow on PPGEEI. Therefore, it was possible to verify that the article was important to bring the discussion of cooperative security, by the American bias, in the African region to the scope of the research in the PGP and to promote the visibility of this problem in the discussion forums and readers of the scientific journal of its publication, fulfilling its objectives of discussing the importance of the South Atlantic to the United States of America, from the discussion of the cooperative security policies for the African West Coast, through the internal political determinants and the change of the region relevance to the global north American grand strategy. Inferring then, the relevance of the South Atlantic in this grand strategy, evidenced by the search for collaborative security initiatives and to combat low intensity threats such as piracy, aiming to contain new threats and face non-state actors.

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