The dissertation focuses on how to best represent the consensus and attitude dynamic of a group given the attitudes of its individuals. This is done in the Bayesian epistemology framework using pooling with imprecise probabilities, and in utility theory extending Harsanyi's aggregation theorem to characterize other directed attitudes like spite and altruism. The final part of the dissertation considers attitudes within social networks and provides explanations and simulation models for online segregation and tribalism as well as the spread of rumors through contagion. The dissertation hopes to contribute to foundational issues like that of epistemic consensus, but also to new emerging phenomena in social epistemology.

The explosion of new political speech in digital formats in the 2008 elections, especially those involving social networking, offered new opportunities and challenges for political journalists, campaign participants and voters alike. This review of new political media in 2008 examines how these new methods of political organizing and communications work and provides insights to further understand how media can best cover and participate in them. The thesis details how 2008 was the first fully Web 2.0 election, exhibiting its characteristics of interactivity, use of databases and the "long tail" of microniche Internet websites. Three new media uses - online, database-driven political speech fact checking as exemplified by PolitiFact; the social networking site Facebook; and interactive, no-cost video streaming on YouTube - illustrate where the changes from traditional political communications to new media are most dramatic. A heightened awareness of emerging political communications forms and a new model for political journalists' interaction with news consumers and vastly different skills sets for reporters will be needed for news media to cover and participate in the new digital electorate.

The Tango Panopticon project merges art with technology to create a live and synchronous art experience which is just as much about the participants as it is about the observers. The goal of this project is to create a dialogue between observers of the event in the hopes of creating new social connections where there were none before. This goal is achieved by allowing observers to view the event from anywhere around the world on a computer via the internet and participate in a dialogue with other users on the website. The other objective of this project is to create a multimedia internet platform for other art projects to use. Other artists that are interested in hosting their own live synchronous event will be able to use the platform we have created and customize it to the specific needs of their project.

Using the 2004 General Social Survey, I illuminate how dispositional optimism as a form of emotional capital enhances personal network range while also contributing to public goods through the formation of heterophilous ties. Network size and diversity are conceptualized as outcomes of optimistic functioning, which is marked by sociability, positive emotion, and problem-focused coping. I find that optimism is linked to substantial leverage in overall, non-kin, and extended network sizes on par with several years of education. Moreover, optimism yields more types of network heterophily than does educational attainment. I discuss limitations of the current study while also identifying future directions for research on emotional capital in the creation of social capital.

Challenging experiences abound in everyday life. Research on relational transgressions predominately favors investigating the nature and outcomes of the experience and how the victim and transgressor respond following the experience. However, individuals are embedded within social networks that provide perceived and enacted support during relational challenges. Research on supportive communication documents the social support process within various contexts by highlighting the benefits and drawbacks of seeking and providing particular kinds of supportive messages. It is likely that social network members play an influential role in an individual's coping process following an experience of feeling wronged by something someone said or did. Literature on coping processes describes coping occurring on levels from individual to communal. If social network members feel wronged or hurt by what happened to the transgressed individual, then coping might occur at the network level. Little research to date has investigated the communicative coping processes within social networks following relational transgressions experiences. In the present study I argue that conversations about coping with relational transgressions influence transgressed individuals' and social network members' perceived stress, feelings about the transgression, forgiveness, and perceived ownership and responsibility of the transgression. Fifty pairs of transgressed individuals and their social network members came to a communication research laboratory and completed a pre-interaction questionnaire, talked with each other about the transgression experience, and completed a post-interaction questionnaire. Participants and third-party observers evaluated the quantity and quality of supportive behaviors during the interaction. Results suggest that participants' perceptions of stress, negative emotions, and motivations for avoidance and revenge related to the transgression experience decreased from pre to post-interaction. Although many of my predictions about the associations between the amount of types of support and quality of support were not supported, results revealed several insightful findings. The amount of emotion support had a negative indirect effect on primary participants' perceptions of stress related to the transgression because of quality of support. I discuss the theoretical and research implication for this and other findings. The communicative coping processes within social networks following relational transgression experiences work in complex and layered ways to influence individual and relational well-being. The present study opens avenues for extending research on communicative coping and repair processes following challenging life experiences.

Cette thèse porte sur la rapidité du temps de mélange de chaînes de Markov sur des graphes. La contribution principale concerne les graphes avec des dynamiques locales sur les arêtes, la topologie du graphe évoluant au fur et à mesure que les arêtes glissent les unes le long des autres. Nous proposons une classification des différents modèles existants de graphes dynamiques, tout en illustrant l’importance des transitions le long d’une structure mouvante pour améliorer la vitesse de convergence. Cette étude est complétée par la preuve, pour l’une de ces dynamiques, d’un temps de mélange rapide. Nous définissons notamment l’expansion partielle d’un graphe. Celle-ci permet de suivre l’avancement de la dynamique, partant d’un état de faible expansion, jusqu’à obtention d’une bonne expansion à l’équilibre. La fin de cette thèse porte sur une amélioration de l’algorithme de simulation parfaite de Propp et Wilson. Nous introduisant un oracle pour les transitions, inspiré de l’échantillonnage préférentiel, qui permet de réduire la complexité de l’algorithme. Nous fournissons une preuve de correction, ainsi qu’une étude de l’impact de cette méthode sur la vitesse d’échantillonnage d’ensembles indépendants pour certains graphes. / This thesis focuses on the rapid mixing of graph-related Markov chains. The main contribution concerns graphs with local edge dynamics, in which the topology of a graph evolves as edges slide along one another. We propose a classification of existing models of dynamic graphs, and illustrate how evolving along a changing structure improves the convergence rate. This is complemented by a proof of the rapid mixing time for one such dynamic. As part of this proof, we introduce the partial expansion of a graph. This notion allows us to track the progression of the dynamic, from a state with poor expansion to good expansion at equilibrium. The end of the thesis proposes an improvement of the Propp and Wilson perfect sampling technique. We introduce oracle sampling, a method inspired by importance sampling that reduces the overall complexity of the Propp and Wilson algorithm. We provide a proof of correctness, and study the performance of this method when sampling independent sets from certain graphs.

Nature-based integration projects present nature and green spaces as an arena for interaction and integration between immigrants and native-born Swedes, and amongst immigrants of different backgrounds. To explore this, the study looks at experiences of NBI projects from the perspective of immigrants who have moved to Sweden and started the process of settling into the new society. The concepts of social networks, as well as structural, cultural, interactive and identificational integration were applied to view the interviewees experiences of nature-based integration activities in Sweden. Qualitative, semi-structured interviews were conducted with eight immigrants', about their participation in NBI projects in Sweden, and how they describe their experiences and perceptions of nature and social interactions. The findings were that time spent in nature was experienced as beneficial for the individual by contributing to their psychological well-being and providing opportunities for socialisation,. Nature in Sweden was depicted as vast, accessible and inclusive when compared with their countries of origin. Interactions and new diversified social networks provided information exchange and novel knowledge. This was seen as one of the entry points to society, and another way in which to understand Swedish cultural traditions, as nature was generally perceived as important in Swedish society. The final results showed that participation in nature-based integration activities was able to contribute to their structural, cultural and interactive integration, but could not be linked to their identificational integration in Sweden.

This paper investigates the development of transnational human rights activists’ networks and how they operate and influence LGBTI human rights activist networks in Uganda against violence on the Ugandan LGBTI communities. The case study, employs semi structured interviews to investigate, how transnational networks are used as a mobilization too in promoting LGBTI human rights in Uganda. Further investigation is done on how transnational networks influence different social networks within local LGBTI activist groups when dealing with violence against the LGBTI communities. The study is taken from a view point of different local LGBTI activist groups and their close link with other international organizations and human rights bodies specifically from countries such as Sweden. Theories surrounding transnational networks and social networks are used in order to frame both cross border relations and local networks among the LGBTI groups. The study also calls for further research on other actors such as transnational migrants and individual activist including social media activist and their impact on the rights of LGBTI in Uganda.

Les réseaux sociaux sont de plus en plus présents dans notre vie de tous les jours et sont en passe de devenir notre moyen de communication et d'information principal. Avec l'augmentation des données qu'ils contiennent sur nous et notre environnement, il devient décisif d'être en mesure d'accéder et d'analyser ces données. Aujourd'hui la manière la plus commune d'accéder à ces données est d'utiliser la recherche par mots-clés : on tape une requête de quelques mots et le réseau social renvoie un nombre fixe de documents qu'il juge pertinents. Dans les approches actuelles de recherche top-k dans un contexte social, la pertinence d'un document dépend de deux facteurs: la proximité sociale entre le document et l'utilisateur faisant la requête et le recoupement entre les mots-clés de la requête et les mots contenus dans le document. Nous trouvons cela limité et proposons de prendre en compte les interactions complexes entres les utilisateurs liés à ce document mais aussi sa structure et le sens des mots qu'il contient, au lieu de leur formulation. Dans ce but, nous identifions les exigences propres à la création d'un modèle qui intégrerait pleinement des données sémantiques, structurées et sociales et proposons un nouveau modèle, S3, satisfaisant ces exigences. Nous rajoutons un modèle de requêtes à S3 et développons S3k, un algorithme personnalisable de recherche top-k par mots-clés sur S3. Nous prouvons la correction de notre algorithme et en proposons une implémentation. Nous la comparons, à l'aide de jeux de données créés à partir du monde réel, avec celle d'une autre approche de recherche top-k par mots-clés dans un contexte social et montrons les différences fondamentales entre ces approches ainsi que les avantages qu'on peut tirer de la nôtre. / Social networks are increasingly present in our everyday life and are fast becoming our primary means of information and communication. As they contain more and more data about our surrounding and ourselves, it becomes vital to access and analyze this data. Currently, the primary means to query this data is through top-k keyword search: you enter a few words and the social network service sends you back a fixed number of relevant documents. In current top-k searches in a social context the relevance of a document is evaluated based on two factors: the overlapping of the query keywords with the words of the document and the social proximity between the document and the user making the query. We argue that this is limited and propose to take into account the complex interactions between the users linked to the document, its structure and the meaning of the words it contains instead of their phrasing. To this end we highlight the requirements for a model integrating fully structured, semantic and social data and propose a new model, called S3, satisfying these requirements. We introduce querying capabilities to S3 and develop an algorithm, S3k, for customizable top-k keyword search on S3. We prove the correctness of our algorithm and propose an implementation for it. We compare this implementation with another top-k keyword search in a social context, using datasets created from real world data, and show their differences and the benefits of our approach.

L'enjeu de ma thèse est de mettre au jour les enjeux qui entourent la croissance des données trouvables en ligne sur les personnes, la multiplication et le fort usage des espaces numériques de sociabilité dont la vocation privée ou professionnelle peuvent tendre à mélanger les deux sphères. L'enjeu du droit des données est confronté au cas du recrutement. Cas où la volonté de valorisation de soi de la part de candidats en recherche d'emploi rencontre le besoin d’évaluation de la part des recruteurs. Le cas du recrutement permet d'aborder différents marchés émergents autour de la réputation numérique, d'interroger les pratiques de part et d'autre du marché du travail (exposition des candidats et recherches des recruteurs) et d'apporter des éléments de connaissances sur les normes de visibilité en cours d'établissement. / The aim of my thesis is to underline what is at stake with the phenomenon of the massive growth of online personal data that we have witnessed for the last decade. This issue is seen through the case of hiring on the labor market. Candidates may want to disclose positive information about themselves and recruiters need to gather as much information as they can to evaluate potential candidates. This example allow us to investigate a new market for online reputation and to bring to knowledge the new norms of visibility and privacy in the age of social media.