Thesis (Ph. D.)--University of Washington, 2008. / Vita. Includes bibliographical references (leaves 609-638).

Thesis (M.S. in Defense Analysis)--Naval Postgraduate School, June 2005. / Thesis Advisor(s): George Lober. Includes bibliographical references (p. 47-51). Also available online.

L’exploration des interactions fondamentales entre les particules subatomiquesa abouti à la construction du Modèle Standard de la physique des particules qui n’a été misen défaut par aucune expérience en laboratoire. Cependant, de sérieuses indications théoriqueset cosmologiques révèlent des insuffisances au Modèle Standard et des déviationssont attendues. Cette nouvelle physique est recherchée auprès des grands collisionneursmettant en jeu des énergies de l’ordre de l’échelle électrofaible et au-delà. A contre-courant,la nouvelle physique pourrait aussi se manifester à très basse énergie, nécessitant des techniquesexpérimentales atypiques. Cette thèse traite des nouvelles forces de courte portéedépendantes du spin, sujet au coeur de la physique de précision à basse énergie. Un gazd’hélium 3 hyperpolarisé a été utilisé comme sonde de cette nouvelle interaction de portéesubmillimétrique. Ce manuscrit présente la meilleure exclusion sur l’intensité du couplagescalaire-pseudoscalaire gsgp pour des portées entre 1 μm et 100 μm correspondant à desmasses inférieures à 1 eV. / The exploration of fundamental interactions between subatomic particles ledto the particle physics Standard Model which remains unchallenged by any lab experiment.However, some serious theoretical and cosmological clues reveal shortcomings inthe Standard Model and deviations are expected. This new physics is searched for at largecolliders with energies of the order of the electroweak scale and beyond. With a differentphilosophy, one can expect the new physics to show up at very low energy using atypicalexperimental techniques. This thesis deals with short-range spin-dependent new forceswhich are at the heart of the low energy precision physics. A hyperpolarized helium 3 gaswas used as a probe of this new sub-mm interaction. This manuscript present the bestexclusion limit on the strength of a scalar-pseudoscalar coupling gsgp for ranges between1 μm and 100 μm, which correspond to sub-eV masses.

La capacité des cellules à sentir les propriétés physiques de leur environnement est un facteur déterminant de l'homéostasie tissulaire. Ainsi, la rigidité de la matrice extracellulaire (forces exogènes) et les tensions du cytosquelette (forces endogènes) coopèrent de manière fonctionnelle modulant les transformations phénotypiques. Les cellules perçoivent et transmettent des forces en développant des structures d'adhérences appelées adhésions focales. Ces adhésions sont composées de protéines transmembranaires, les intégrines, qui font le lien entre le cytosquelette et la matrice extracellulaire.La partie centrale de mon projet de thèse aborde la question du couplage des intégrines b1 et b3 dans la mécanotransduction. Les données actuelles plaident fortement en faveur d'une relation bidirectionnelle entre l'adhésion intégrine-dépendante et les forces mécaniques générées dans ce processus. Les approches génétiques classiques ont souligné le rôle majeur des intégrines b1 et b3 dans mécanosensibilité cellulaire, sans préciser leur contribution relative. Par exemple, la manière dont la modulation de l'expression de l'intégrine b3 affecte la génération des forces de traction cellulaires et la distribution des adhésions intégrines-dépendantes reste à être explorées. Dans ce travail de thèse nous avons montré que les intégrines b1 ont un rôle essentiel dans la génération de forces cellulaires, que les intégrines b1 sont régulées négativement par les intégrines b3 en affectant la distribution spatiale des intégrines b1 à travers leur capacité à lier à la fois la taline et la kindline. Et enfin, nous avons montré que les intégrines b3 régulent temporellement l'activité contractile de la cellule.J'ai également participé à deux autres études dans le cadre de collaborations avec le Pr. Holmgren et le Dr. Debili, au cours desquelles j'ai utilisé la microscopie à traction de forces comme un outil diagnostique afin d'observer l'effet des forces contractiles dans la formation de la lumen aortique et de la formation des plaquettes sanguines. J'ai ainsi pu confirmer que la protéine amotL2, reliant les fibres contractiles aux VE-cadhérines, est impliquée dans la force intercellulaire nécessaire à la formation de la lumen aortique. Et lors d'une deuxième collaboration, j'ai pu montrer que la contractilité des mégacaryocytes, via leur système actomyosine, est nécessaire pour la formation des proplaquettes. / Cell ability to sense mechanical properties of their microenvironment is crucial for tissue homeostasis which means their capacity to maintain mechanical integrity as they are submitted to external forces.Integrins have been highlighted as mechanotransducers able to form micro-scale structures called focal adhesion sites which mechanically link cells to the extracellular matrix by recruiting various adaptors. Both b1 and b3 integrins have been identified as the principal actors of tensional homeostasis. However as the resulting mechanotransduction processes are intrinsically dynamic, the respective and cooperative roles b1 and b3 integrins need to be addressed over time and space.In the present work, coupling time-resolved traction force microscopy and genetics approaches, we investigated the respective role of b1 and b3 integrins in active force generation at the single cell level. Our findings show that b1 integrins has an essential role in generation of cellular traction forces, b1 integrin-generated force is negatively regulated by b3 integrins which impacts the redistribution of b1 integrin containing adhesion through its ability to bind to talin and kindlin, b3 integrin supports min-scale temporal regulation of cellular contractile activity generated by b1 integrin. Finally, cell mechanical equilibrium relies on the ability of cells to maintain a fixed contractile moment.I also participated in two others studies in the framework of collaborations in which I used the traction force microscopy as a diagnostic tool to observe the effect of contractile forces in the formation of the aortic lumen and the formation of proplatelets. I was able to confirm that the protein amotL2 connecting the contractile fibers to VE-cadherin, is involved in intercellular forces necessary for the formation of the aortic lumen. And in a second collaboration, where I found by using traction force microscopy that the contractility of megakaryocytes via its actomyosin system, is necessary for the formation proplatelets.

This work presents first-principles calculations of long-range intermolecular dispersion energies between two atoms or molecules as expressed in terms of the C6 dipole-dipole dispersion coefficients. In a series of publications, it has been shown by us that the complex linear polarization propagator method provides accurate ab initio and first-principles density functional theory values of the C6 dispersion coefficients in comparison with those reported in the literature. The selected samples for the investigation of dispersion interactions in the electronic ground state are the noble gases, n-alkanes, polyacenes, azabenzenes, and C60. It has been shown that the proposed method can also be used to determine dispersion energies for species in their respective excited electronic states. The C6 dispersion coefficients for the first π → π* excited state of the azabenzene molecules have been obtained with the adopted method in the multiconfiguration self-consistent field approximation. The dispersion energy of the π → π* excited state is smaller r than that of the ground state. It is found that the characteristic frequencies ω1 defined in the London approximation of n-alkanes vary in a narrow range and that makes it possible to construct a simple structure-to-property relation based on the number of -bonds for the dispersion interaction in these saturated compounds. However, this simple approach is not applicable for the interactions of the π-conjugated systems since their characteristic frequencies ω1 vary strongly depending on the systems. / <p>Report code: LIU-TEK-LIC-2006:2</p>

Doctorat en droit / info:eu-repo/semantics/nonPublished

Notre thèse s’intéresse à la couverture médiatique de la BBC pendant la guerre en Irak (2003) et s’interroge sur son impact politico-militaire dans les médias. Afin d’examiner la délicate relation entre la couverture médiatique des guerres récentes et l’opinion publique, notre thèse s’appuie sur une analyse quantitative et qualitative des bulletins d’informations de la BBC ainsi que sur divers documentaires. Il en découle plusieurs constats : à l’image des médias anglo-américains, la BBC demeure perméable à la propagande de guerre et privilégie la communication propre aux Relations Publiques. Sa complicité avec le gouvernement britannique témoigne de son rôle de garant mais aussi de celui d’acteur politique et public. En effet, notre étude de la couverture de cette guerre démontre un glissement du statut de la BBC qui, d’observateur actif et critique, tend à devenir un observateur partial et sélectif. Bien plus, la gestion de l’information et les contraintes culturelles qui y sont liées ont contribué à faire évoluer la couverture de cette guerre qui devait être « politiquement correcte » du point de vue britannique. Ceci a permis de renforcer ce que l’on pourrait envisager comme la possible illustrationd’une complicité voire d’une allégeance politique de la BBC. La « Corporation », ainsi fidèle serviteur d’une « censure patriotique », est partie prenante dans la construction d’un récit militaire épuré et transforme la couverture médiatique de cette guerre en une propagande volontaire. Dans cette guerre en Irak, à l’image du reste des médias, la BBC ne résiste pas aux pressions politiques. L’utilisation de l’« infotainment » par les forces de coalition vise à reconstituer « la réalité de la guerre » et à mettre en avant le prestige des alliés en présentant leur victoire comme indéfectible et incontestée, dans un cadre bien circonscrit, afin de répondre aux attentes du public mais aussi de renforcer son récit patriotique et d’éradiquer toute déception politique et/ou culturelle. Enfin, la couverture de ce conflit par la BBC tend à minimiser l’impact des révélations émanant des médias adversaires et propose une présentation apparemment plus objective de penser la guerre / This dissertation explores the BBC’s coverage of the 2003 Iraq War. It investigates the implications of the politico-military intervention in Iraq for the media system. In examining the sensitive relationship binding the media coverage of contemporary wars and public opinion, this thesis is based upon quantitative and qualitative analysis of BBC news bulletins as well as different documentaries. This investigation shows that, along with the rest of the British-American media, the BBC was susceptible to war propaganda and favoured the kind of communication specific to Public Relations. Its complicity with the British government shifted its role from a watchdog to a publicist and political agent. In fact, our study of the Iraq War coverage chronicles the transition of the BBC from an active, critical and communicative medium into a simply passive, partial and selective observer. Moreover, the news management and the cultural as well as political constraints helped to transform the coverage of this war which had to be “politically correct” from a British perspective. This helped reinforce what could be considered as a possible illustration of the BBC’s complicity and even its political allegiance. The Corporation, afaithful servant of “patriotic censorship” was involved, as a partner, in the construction of a sanitized military story and transformed its coverage of the war into voluntary propaganda. During the Iraq War, like the rest of the media, the BBC could not resist political pressure. The Coalition’s use of “infotainment” aimed to exploit the “reality of war” and highlight, in a well-defined context, the prestige of the Allies by presenting their victory as ineluctable and unquestioned, not only in order to meet the expectations of the public but also to enhance a patriotic narrative and eradicate all political and / or cultural disappointment. Finally, the BBC’s coverage of this conflict tended to minimize the impact of revelations in enemy media and offers a presentation of how to think about war.

Le contrôle de la friction en régime limite s’effectue par le biais de lubrifiants qui, par l’adsorption de molécules sur les surfaces, réduisent les contacts directs entre aspérités. Dans ce contexte, l’objectif de cette thèse est de comprendre et de coupler les mécanismes, à la fois, d’adsorption et d’auto-organisation de différents acides gras sur des surfaces, et les mécanismes de friction interfaciale sous des conditions stationnaires et transitoires. L’effet de l’architecture moléculaire, modifiée par la présence et la conformation d’une insaturation dans la chaîne aliphatique des acides gras, a également été analysé. La caractérisation in-situ, à l’échelle moléculaire, a été réalisée avec le tribomètre moléculaire ATLAS développé au LTDS. Cet appareil permet des déplacements quasi-statiques et dynamiques, d’une sphère mise en regard d’un plan, suivant trois axes. Trois solutions d’acides gras, en faible concentration dans du dodécane, ont été analysées. Les déplacements et les forces, normaux et tangentiels, sont mesurés à l’aide de capteurs capacitifs d’une résolution respective de 0.015 nm et 10 nN. Des sollicitations dynamiques superposées permettent de caractériser simultanément la rhéologie de l’interface confinée en termes d’amortissement et de raideur, dans les deux directions. Les résultats montrent que les acides gras s’adsorbent par interaction physique sur les surfaces pour former des films visco-élastiques d’une épaisseur d’environ 15 Å sur chaque surface. Le taux de couverture et la cinétique d’adsorption de ces couches dépendent de l’architecture moléculaire des acides gras. Cette dernière gouverne également la friction interfaciale, qui a été qualifiée de supraglissement, et la rhéologie des monocouches auto-assemblées. Les différentes organisations de films conduisent ainsi à différentes évolutions de la friction en fonction de la vitesse de glissement et de la pression de contact. La réponse en friction transitoire et l’accommodation lors du glissement vers un nouvel état stationnaire ont de plus été décrites par des distances caractéristiques, de plusieurs nanomètres, reflétant le renouvellement statistique des spots de contact, et par des temps de relaxation, de l’ordre de la seconde, décrivant le réarrangement moléculaire au sein de l’interface. Enfin, une modélisation théorique de la friction limite a été proposée afin de comprendre l’origine moléculaire de la friction entre monocouches d’acides gras mettant ainsi en évidence le couplage fort de deux échelles spatiales et temporelles. / Friction in boundary lubrication can be controlled by the adsorption of molecules on surfaces that reduce direct contacts between asperities. In this context, the aim of this thesis is to understand and to couple the mechanisms of adsorption and self-organization of different fatty acids on surfaces, with the mechanisms of interfacial friction under steady-state regime and transient conditions. The effect of the molecular architecture, modified by the presence and conformation of one unsaturation in the aliphatic chain of fatty acids, was also analyzed. In-situ characterization, at the molecular level, was performed with the molecular tribometer ATLAS, developed at LTDS. This apparatus allows quasi-static and dynamic displacements, of a sphere in front of a plane in three directions. Three fatty acids solutions, in low concentration in dodecane, were analyzed. The displacements and the forces, normal and tangential, are measured using capacitive sensors with a resolution of 0.015 nm and 10 nN respectively. Dynamic superimposed measurements allow a simultaneous rheological characterization of the confined interface in terms of damping and stiffness in two directions. The results show that the fatty acids adsorb on the surfaces by weak interactions and form viscoelastic films with a thickness of about 15 Å on each surface. The coverage rate and adsorption kinetics of these layers depend on the molecular architecture of the fatty acids. This architecture also governs interfacial friction, which has been described as superlubricity, and the rheology of self-assembled monolayers. Various film organizations have thus led to different evolutions of the friction as a function of the sliding speed and the contact pressure. The transient friction response and its accommodation during slip to a new stationary state have also been described by characteristic distances of several nanometers, reflecting the statistic average renewal of the contact spots, and by relaxation times of the order of the second, describing the molecular rearrangement within the interface. Finally, theoretical modeling of boundary friction has been proposed to understand the molecular origin of the friction between monolayers of fatty acids and highlight the strong coupling between both spatial and temporal scales.

Peacekeeping operations were started by the United Nations following the collapse of the collective security system which was hinged on the cooperation of the major powers as proposed in the United Nations Charter. The United Nations Charter however does not give a definition of peacekeeping, making it difficult for nation states and various agencies to delineate the limits of Peacekeeping. However, the Charter provides a comprehensive number of platforms in which different kinds of threats pertaining to international peace and security may be dealt with. In the backdrop to this, peacekeeping endeavours have over the years come to be defined as Chapter six and a half, descending between Chapter six and Chapter seven of the United Nations Charter. The Charter reveals that the purpose of the United Nations is to maintain International Peace and Security (United Nations 1985:6). As a member of the International Community and its commitment to Peace and International Security, Botswana is obliged to take part in International interventions aimed at bringing peace, security and stability to Africa and the rest of the world. To this end the government of Botswana is always ready to release and deploy peacekeepers anywhere such calls are made by regional bodies such as the UN, AU or SADC. (Muyakwabo, 2013:2). The intervention of the BDF in the Somali civil war of 1992-1994 is a classic example of Botswana’s commitment to International Peace and Security. In response to the call by UN to assist Somalis, Botswana deployed a battalion sized BDF contingent of Peacekeepers to the United Nations Operation in Somalia (UNOSOM) to help bring peace and security to the nation of Somalia. (Bachelor, Kingman and Lamb 2000:21). This research study is an exploratory investigation into the experiences of the first Botswana Defence Force Peacekeepers who were deployed in the United Nations Peacekeeping Mission in Somalia (UNOSOM) 1993-1995. Seventeen peacekeepers were interviewed who have participated in both UNOSOM I and UNOSOM II. A thematic analysis of the text was undertaken, in which themes emerged to document and highlight the difficulties that the peacekeepers experienced in Somalia. Narratives from the transcribed interviews were reviewed with the participants and logical analysis by the researcher provided further clarification of the data to understand the experiences of the peacekeepers. The peacekeepers’ descriptions of the situations they faced on the ground provided a new way into understanding the intricacies of traditional peacekeeping. Three fundamental themes emerged: the importance of peacekeeping education and training; the importance and need of logistical support, personal and contingent preparation; and the way forward in ensuring successful and effective peacekeeping by African armies.

Sea water intake structures submerged in the surf zone are used to provide water for cooling processes in large facilities such as power plants and refineries. Structures submerged in the surf zone are subject to large forces from breaking waves. To study these forces induced from realistic sea state conditions, a physical model of an intake structure submerged in the wave breaking zone was constructed and subjected to a wide spectrum of regular and irregular waves. The model structure was designed in a manner so force measurement could be isolated to separate components of the structure. The data of peak forces on the structure was analyzed for correlations with varying irregular wave properties. Using the results of forcing on the structure from regular wave tests, drag and inertia coefficients for use in the Morison equation were determined for each separate component and configuration of the structure. These force coefficients were plotted against various wave properties to analyze correlations with wave conditions. Finally, the force coefficients for the structure were used with the Morison equation and current data from the experiments to successfully model forcing on the structure during irregular wave tests.