The Sahelian Niger farming systems spatial expansion over the last century is about to reach its end. Meanwhile, rural societies organizations & managements of economic activities have evolved. This research objective is to develop an integrative approach to evaluate the impact of social factors on farming system transitions. The study focuses on three contrasted sites of Sahelian Niger. Regional, village & individual level interviewing tools are used to define differentiated individual behavior rules to be translated into an Agent-based model simulating the populations & their related "terroirs" along two or three generations. The model is based on reactive individual agents acting empirically, i.e. without optimisation processes. The model is realistic concerning the individual behaviors & realistically simulates their impacts on village populations & natural resources. Simulation results show that once dominant unitary families have shifted towards non-cooperative ones around the 70's. Simulations with no transition processes of inheritance system & family organization show that villages specialize themselves: more a "terroir" is well endowed, more its population involves itself in local activities. Introducing such processes, differentiation occurs within the population level, subdividing it into specializing groups according to their village anteriority & manpower & land availability. Introducing development proposals (inorganic fertilizer availability & yield-based inventory credit) reinforce this social differentiation: only well-endowed sites & among them, only favored groups have the saving capacity to get involved. The securizing inventory credit proposal has more success than the intensification-oriented inorganic fertilizer use. Combining different individual-level tools in a multidisciplinary approach is efficient in underlining the impact of micro level constraints on long-term population evolutions in such constrained environments. Such approach may be used in development diagnosis to identify the constraint hierarchy affecting differentially the population. Simulating population behaviors keep open epistemological debates that have strong implications for rural populations.

This thesis explores the relationship between education and employment, particularly as it affects the socio-economic mobility of people from poor and marginalized communities in Nepal. I carry out a multi-sited, inter-generational analysis to investigate the aspirations, expectations, and experiences of young people. Based on ethnographic and participatory fieldwork in a village and a school in the outskirts of Lalitpur in 2012, this research grows organically to provide a detailed review of current schooling practices and their employment as well as wider implications in Nepal. Theoretically, this thesis investigates the experiences of the marginalized in terms of the relevance, level, and quality of their education. I examine the role of education as a socializing institution as well as its characteristics as a social and a positional good. I assess the outcomes of their education through internal measures (such as exam scores and pass rates) but also extend the analysis to include external ones (such as job opportunities and life trajectories). I focus on the deterministic life-stages model of transition to challenge the expectation that children go to school, acquire skills, obtain jobs, and become 'adults'. People have historically placed high hopes on education, but the potential for socio-economic mobility for the poor and marginalized are limited by the failures of the school system, sustained challenges to higher education access, limited relevance of education to employment opportunities, and continued prominence of social and cultural capital to secure jobs. Yet, their educational engagement has provided some benefits even as their expectations for gainful employment have not been met. Schooling has become an integral part of childhood, but foreign migration is emerging as a prominent alternative avenue for the aspirant youth. Further, the distinctions between children and adults are also blurred as students balance their transitions between school, work, and home to succeed within the system.

Les transitions agroécologiques impliquent une transformation radicale des modes de production, mais également des modes de transformation, de distribution et de consommation, du conseil agricole, des politiques publiques et de la recherche - en d’autres termes : une reconfiguration du système agri-alimentaire. Dans la vallée de la Drôme, la forte proportion d’acteurs plaçant l’agriculture biologique au coeur de leur stratégie de développement et leur collaboration dans le projet Biovallée semblent indiquer qu’une transition agroécologique est en cours et que l’échelle territoriale offre des leviers permettant de la déclencher. Cette thèse propose une analyse historique des dynamiques à l’oeuvre sur ce territoire, afin de contribuer à la compréhension des mécanismes de transition et à leur conceptualisation. En mobilisant la théorie des transitions sociotechniques et à travers une approche pragmatique et ethnographique, nous montrons qu’une reconfiguration du système agri-alimentaire territorial est en cours, et qu’elle résulte des interactions entre une configuration sociotechnique dominante et deux configurations alternatives qu’ont construites les acteurs au fil du temps, autour de deux paradigmes alternatifs à la modernisation agricole. Nous montrons comment, à travers ces interactions, les acteurs parviennent à modifier les rapports de force régissant le système agri-alimentaire, et que l’échelle territoriale leur offre des marges de manoeuvre inexistantes à une échelle plus large. Nous mettons en évidence le rôle essentiel d’une diversité d’initiatives, au sein desquelles les acteurs ont progressivement construit de nouvelles formes de coordination. Dès lors, la question est non plus de penser les transitions à partir du développement d’une innovation technique, mais de créer les conditions pour favoriser la coexistence d’une diversité d’initiatives, porteuses d’innovations sociales, et leurs interactions avec le système dominant. / Agriculture’s transition towards agrocology requires a radical transformation of production practices based on ecological principles, but it also requires radical changes within transformation, distribution and consumption practices and within advisory systems, public policies and research. In other words, it requires a profound reconfiguration of the whole agrifood system. In the Drome Valley (France), the high proportion of actors who consider organic agriculture as central in their development strategy and their involvement within the “Biovallée” project, suggest that an agroecological transition is in process and that the territorial scale might facilitate it. This thesis analyses the agricultural dynamics at the scale of this territory since the 1970s, in order to understand the transition mechanisms and to conceptualize them. Based on a framework inspired from the sustainable transition theories and on an ethnographic and pragmatic approach, it shows that a reconfiguration of the whole local agrifood system is indeed in process, and that it results from the interactions between a dominant sociotechnical configuration and two alternative ones which local actors have set up over time around two alternative paradigms. We analyze how actors succeed in changing the balance of power within the local agri-food system and how the territorial scale offers them some levers which do not exist on a larger scale. In this case, certain traditional actors and a diversity of initiatives allowed actors to progressively set up new forms of coordination, that is social or organizational innovations (rather than technological ones). Therefore the main issue shifts from thinking transitions based on the development of atechnological innovation, towards creating conditions in order to favour the coexistence of a diversity of initiatives that develop social innovations and to favour their interactions with the dominant system.

La mécanique statistique des systèmes auto-gravitants constitue un des plus fascinants et mystérieux champs de recherche. À cause de la nature à longue-portée de la force gravitationnelle, la notion usuelle d'équilibre statistique est modifiée, faisant de cette étude un problème hors-équilibre. Par conséquent, ces systèmes exhibent certaines propriétés particulières comme, par exemple, l'existence de transitions de phase associées à un effondrement gravitationnel. Le travail présenté dans cette thèse a comme but une description détaillée des transitions de phase dans un cadre général relativiste en considérant, en particulier, le cas des fermions auto-gravitants. La thèse est conceptuellement divisée en trois parties, selon le niveau de dégénérescence du système. D'abord, nous focalisons notre attention sur le cas des fermions dégénérés (T = 0), en étudiant en détail l'équilibre gravitationnel. Ensuite, en considérant la limite de haute température (T >> 1), nous montrons l'existence de deux types d'effondrement gravitationnel dans les séries d'équilibre. Enfin, nous explorons le cas général, en illustrant la présence des transitions de phase gravitationnelles, soit dans l'ensemble micro-canonique soit dans l'ensemble canonique. / The statistical mechanics of self-gravitating systems constitutes one of the most fascinating and puzzling fields of research. Due to the long-range nature of the gravitational force, the usual notion of statistical equilibrium is modified, making of this study an out-of-equilibrium problem. As a consequence, these systems exhibit some peculiar features such as the occurrence of phase transitions associated with a gravitational collapse. The work presented in this thesis aims at providing a detailed description of the phase transitions in a general relativistic framework by considering, in particular, the case of self-gravitating fermions. The thesis is conceptually divided in three parts, according to the degeneracy level of the system. We firstly focus our attention on the case of degenerate fermions (T = 0), by studying in detail the gravitational equilibrium. Successively, considering the high temperature limit (T >> 1), we show the existence of two kinds of gravitational collapse in the series of equilibria. Finally, we explore the general case, by illustrating the occurrence of the gravitational phase transitions, in both microcanonical and canonical ensembles.

abstract: This dissertation explores the functional purpose of imagination as it is enacted in the context of shaping large transitions in sociotechnical systems. Large sociotechnical systems undergoing profound transitions embody instantiations where societies experience profound changes in the ‘rules of the game’ that underpin the conduct of daily life. The forms of imagination that guide these transformations, known in the political theory literature as ‘imaginaries,’ play a profound yet undertheorized role in transition of sociotechnical systems from one configuration to another. Expanding on this relationship, the study draws on three case studies of energy systems change in the United States during 20th and 21st century. Each case study explores unique element of how actors at a variety of levels – transnational governance, regional electrification, and in-home energy marketing – define and the possibilities for ideal human and technological action and interaction through a transition. These actors defining the parameters of a new form of systems operation and configuration are as equally focused on defining how these new configurations shape fundamental ideas that underpin American democratic sensibility. Moreover, in the process of articulating a new configuration of energy and society – be that in terms of managing global resource flows or the automation of energy use in a residential home – questions of what makes an ideal member of a society are interlinked with new contractual relationships between energy producers and energy users. Transitions research could and should pay greater attention to the normative commitments emergent systems actors – as it is in these commitments we can chart pathways to redefine the parameters that underpin emergent transitions. / Dissertation/Thesis / Doctoral Dissertation Human and Social Dimensions of Science and Technology 2018

Dans cette thèse nous utilisons des méthodes globaux de prédiction des structures cristallographiques combinés à des techniques de grande capacité de traitement de données afin de prédire la structure cristalline de différents systèmes et dans des conditions thermodynamiques variées. Nous avons réalisé des prédictions structurales utilisant l'analyse cristalline par optimisation par essaims particuliers (CALYPSO) combinés avec la Théorie Fonctionnel de la Densité (DFT) ce qui a permis de mettre en évidence la stabilité de plusieurs composés jusqu'à la inconnus dans le digramme de phases du système Ba-Si et dans le système N-H-O. Nous avons également réalisé une étude à haute capacité de traitement de données sur un système ternaire de composition ABX2. Nous avons utilisé la Théorie Fonctionnel de la Densité combinant calculs de prototypes structuraux à partir des prédictions structurelles avec la méthode. Dans les paragraphes suivants nous résumons le contenu de différents chapitres de cette thèse. Le premier chapitre qui constitue une brève introduction au travail de cette thèse est suivi du chapitre 2 présentant les aspects théoriques utilisés dans ce travail. D'abord il est fait une brève introduction à la Théorie Fonctionnel de la Densité. A continuation nous décrivons quelques fonctions d'échange-corrélation choisies qui constituent des approximations rendant l'utilisation de la DFT efficace. Ensuite nous présentons différents procédés de prédiction structurale, et en particulier les algorithmes d'optimisation par essaims particuliers et de « Minima Hopping » qeu nous avons utilisés dans cette thèse. Finalement il est discuté comment doit-on se prendre pour évaluer la stabilité thermodynamique des nouvelles phases identifiées. Dans le chapitre 3, nous considérons le système Ba-Si. A travers l'utilisation d'une recherche structurale non-biaisée basée sur l'algorithme d'optimisation par essaims particuliers combinée avec des calculs DFT, nous faisons une étude systématique de la stabilité des phases et de la diversité structurale du système binaire Ba-Si sous haute pression. Le diagramme de phases résultant est assez complexe avec plusieurs compositions se stabilisant et se déstabilisant en fonction de la pression. En particulier, nous avons identifié des nouvelles phases de stœchiométrie BaSi, BaSi2, BaSi3 et BaSi5 qui devraient pouvoir être synthétisées expérimentalement dans un domaine de pressions étendu. Dans le chapitre 4 est présentée notre étude du diagramme de phases du système N-H-O. S'appuyant sur une recherche structural «évolutive » de type ab initio, nous prédisons deux nouvelles phases du système ternaire N-H-O qui sont NOH4 et HNO3 à de pressions allant jusqu'à 150 GPa. La nouvelle phase de NOH4 est stable entre 71 et 150 GPa, tandis que HNO3 est stable entre 39 et 150 GPa (la pression maximum de cette étude). Ces deux nouvelles phases sont lamellaires. Nous confirmons également que la composition NOH5 perd son stabilité pour des pressions supérieures à 122 GPa se décomposant en NH3 et H2O à cette pression. Le chapitre 5 se focalise sur les électrodes transparentes de type-p à base des chalcogénures ternaires. Nous utilisons une approche à grande capacité de traitement de données basée sur la DFT pour obtenir la delafossite et d'autres phases voisines de composition ABX2. Nous trouvons 79 systèmes qui sont absents de la base de données « Materials project database », qui sont stables du point de vue thermodynamique et qui cristallisent soit dans la structure delafossite, soit dans des structures très proches. Cette caractérisation révèle une grande diversité de propriétés allant depuis les métaux ordinaires aux métaux magnétiques et permettant d'identifier quelques candidats pour des électrodes transparents de type-p. Nous présentons enfin à la fin du manuscrit nos conclusions générales et les perspectives de ce travail / In this thesis we use global structural prediction methods (Particle Swarm Optimization and Minima Hopping Method) and high-throughput techniques to predict crystal structures of different systems under different conditions. We performed structural prediction by using the Crystal structure Analysis by Particle Swarm Optimization (CALYPSO) combined with Density Functional Theory (DFT) that made possible to unveil several stable compounds, so far unknown, on the phase diagrams of Ba-Si systerm and N-H-O system. Afterwards, we performed a high-throughput investigation on ternary compounds of composition ABX2, where A and B are elements of the periodic table up to Bi, and X is a chalcogen (O, S, Se, and Te) by using density functional theory and combining calculations of crystal prototypes with structural prediction (Minima Hopping Method). The following paragraphs summarize the content by chapter of this document. Chapter 1 is a short introduction of this thesis. Chapter 2 consists of the basic theory used in this thesis. Firstly, a short introduction of Density Function Theory (DFT) is presented. Then, we describe some approximate exchange- correlation functions that make DFT practical. Next, we introduce different structural prediction algorithms, especially Particle Swarm Optimization and Minima Hopping Method which we used in this thesis. Finally, we discuss the thermodynamic stablility criteria for a new a new structure. In Chapter 3, we first consider Ba–Si system. Using an unbiased structural search based on a particle-swarm optimization algorithm combined with DFT calculations, we investigate systematically the ground-state phase stability and structural diversity of Ba–Si binaries under high pressure. The phase diagram turns out to be quite intricate, with several compositions stabilizing/destabilizing as a function of pressure. In particular, we identify novel phases of BaSi, BaSi2, BaSi3, and BaSi5 that might be synthesizable experimentally over a wide range of pressures. Chapter 4 contains the investigation of the phases diagram of the N–H–O system. By using ab initio evolutionary structural search, we report the prediction of two novel phases of the N–H–O ternary system, namely NOH4 and HNO3 (nitric acid) at pressure up to 150 GPa. Our calculations show that the new C2/m phase of NOH4 is stable under a large range of pressure from 71 GPa to 150 GPa while the P21/m phase of HNO3 (nitric acid) is stable from 39 GPa to 150 GPa (the maximum pressure which we have studied). We also confirmed that the composition NOH5 (NH3H2O) becomes unstable for pressures above 122 GPa. It decomposes into NH3 and H2O at this pressure. Chapter 5 focuses on p-type transparent electrodes of ternary chalcogenides. We use a high-throughput approach based on DFT to find delafossite and related layered phases of composition ABX2, where A and B are elements of the periodic table, and X is a chalcogen (O, S, Se, and Te). From the 15 624 compounds studied in the trigonal delafossite prototype structure, 285 are within 50 meV/atom from the convex hull of stability. These compounds are further investigated using global structural prediction methods to obtain their lowest- energy crystal structure. We find 79 systems not present in the "Materials project database" that are thermodynamically stable and crystallize in the delafossite or in closely related structures. These novel phases are then characterized by calculating their band gaps and hole effective masses. This characterization unveils a large diversity of properties, ranging from normal metals, magnetic metals, and some candidate compounds for p-type transparent electrodes. At the end of the thesis, we give our general conclusion and an outlook

The chair/dean relationship often has a direct impact on departmental success. What happens when the there is a change in deanship? The presenters will share their experience of having five deans in five years. Through case studies and dialogue, strategies for navigating dean transitions will be shared and examined.

Les études et les résultats présentés dans ce manuscrit ont pour but de développer une meilleure compréhension des principes à la base de l'auto-organisation dans les systèmes biologiques. La théorie topologique des transitions de phase est l'un des approches possibles pour fournir une généralisation de la description des transitions de phase dans les systèmes petits ou mésoscopiques. Cette théorie a été rigoureusement enracinée dans deux théorèmes: un contre exemple à l'un de ces théorèmes a été récemment découvert. La première partie de ce manuscrit est donc consacré à mieux comprendre ce «contre-exemple » pour verifier si et comment la théorie peut être sauvé.Dans la deuxieme parte de ce manuscrit les résultats des recherches théoriques, numériques et expérimentales sur la condensation à la Fr "ohlich sont reportés. Ceci est une condition préalable à l'activation des oscillations dipolaires géantes qui entraînent des interactions électrodynamiques à long portée entre les molécules coresonnantes. Dans cette thèse, on montre que les interactions à longue portée affectent sensiblement les propriétés de diffusion des molécules en solution. Une empreinte des interactions à long portée pourrait être un phénomène de «transition» en ce qui concerne le coefficient de diffusion en fonction d'un paramètre de contrôle proportionnel à l’intensité d'interaction. Simulations analogues ont été réalisées afin de valider une approche expérimentale visant à trouver une telle «empreinte» dans les systèmes avec interactions à longue portée. / The studies and results reported in this manuscript are aimed to develop a deeper understanding of the principles at the basis of self-organization in biological system.The Topological Theory of phase transitions is one of the possible approaches to provide a generalization of description of phase transitions in small or mesoscopic systems. This theory has been rigorously rooted in two theorems: a counterexample to one of these theorems has been recently found. The first part of this manuscript is devoted to investigation of the "counterexample" to understand if and how the theory can be saved. In the second part of this manuscript the results of theoretical, numerical and experimental investigations on Fr"ohlich-like condensation for normal modes of biomolecules are reported. This is a prerequisite for the activation of giant dipole oscillations in biomolecules which entail long-range electrodynamic interactions between coresonant molecules. In this thesis is shown that long-range interactions markedly affect the self-diffusion properties of molecules in solution. A fingerprint of long-range interactions could be a "transitional" phenomenon concerning the self-diffusion coefficient as a function of a control parameter proportional to interaction strength. Analogous simulations have been performed to validate an experimental approach aimed at finding such "fingerprint" in systems with built-in long-range interactions.

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The global energy system is dominated by the use of fossil fuels. This system suffers from several problems, such as different environmental issues, while the long-term energy security is sometimes questioned. As an alternative to this situation, a transition to a global energy system based on renewable energy technologies, to a large extent solar and wind energy, is commonly proposed. Constructing the technology needed for such a transition requires resources and how fast this could happen is somewhat disputed. This thesis explores methods to assess the potential constraints for realizing such a transition by looking at potential technology growth rates and outlooks of production of the required natural resources. The thesis is based on three papers presenting case studies that look at growth rates of wind energy as well as future production outlooks of lithium and phosphate rock. Using different types of growth patterns reaching proposed installed capacities of wind power, annual commissioning requirements are investigated, taking account for the limited life expectancy oftechnology. Potential outlooks of mineral production are explored using resource constrained curve-fitting models on global lithium production. A more disaggregated model looking at individual countries are used on phosphate rock production to investigate new perspectives on production outlooks. It is concluded that the growth rates of individual energy technologies affect the resource requirements and prospective constraints on energy transitions. Resource constrained modelling of resource production can provide spans of potential outlooks for future production of resources required for anenergy transition. A higher disaggregation of the modelling can provide new perspectives of potential constraints on future production. These aspects should be further investigated when proposing alternative future energy systems.