In der Schweiz wird die Diskussion um eine Testosteron-Behandlung gerade beim älteren Mann sehr konservativ und mit vielen Vorbehalten geführt. In der schweizerischen Fachliteratur finden sich keine nationalen Guidelines zu diesem Thema. In Zeitungsartikeln in schweizerischen Fachzeitschriften wird die Testosteron-Behandlung befürwortet, aber mit vielen Einschränkungen und Vorbehalten versehen. Daraus lässt sich eine Gruppe von „offenen Fragen“ zusammenstellen, die in der Folge aufgrund der aktuellen internationalen Fachliteratur diskutiert werden. / The discussion about testosterone therapy is hold in Switzerland in a conservative way and with many objections. In the Swiss medical literature there are no national guidelines published about this object. In publications in Swiss medical papers the testosterone therapy is approved but with many restrictions and reservations. There are some "open questions" collected together and discussed comparing the actual international medical literature.

This thesis consists of five papers, presented as separate chapters within three parts: Industrial Organization, Evolutionary Game Theory and Game Theory. The common basis of these parts is research in the field of game theory and more specifically, equilibrium selection in different frameworks. The first part, Industrial Organization, consists of one paper co-authored with Prajit Dutta and Jörgen Weibull. Forward-looking consumers are analysed in a Bertrand framework. It is assumed that if firms can anticipate a price war and act accordingly, so can consumers. The second part, Evolutionary Game Theory, contains three chapters. All models in these papers are based on Young’s (1993, 1998) approach. In Chapter 2, the Saez Marti and Weibull’s (1999) model is generalized from the Nash Demand Game to generic two-player games. In Chapter 3, co-authored with Jens Josephson, a special set of stochastically stable states is introduced, minimal construction, which is the long-run prediction under imitation behavior in normal form games. In Chapter 4, best reply and imitation rules are considered on extensive form games with perfect information. / Diss. Stockholm : Handelshögsk., 2001

In der Schweiz wird die Diskussion um eine Testosteron-Behandlung gerade beim älteren Mann sehr konservativ und mit vielen Vorbehalten geführt. In der schweizerischen Fachliteratur finden sich keine nationalen Guidelines zu diesem Thema. In Zeitungsartikeln in schweizerischen Fachzeitschriften wird die Testosteron-Behandlung befürwortet, aber mit vielen Einschränkungen und Vorbehalten versehen. Daraus lässt sich eine Gruppe von „offenen Fragen“ zusammenstellen, die in der Folge aufgrund der aktuellen internationalen Fachliteratur diskutiert werden. / The discussion about testosterone therapy is hold in Switzerland in a conservative way and with many objections. In the Swiss medical literature there are no national guidelines published about this object. In publications in Swiss medical papers the testosterone therapy is approved but with many restrictions and reservations. There are some "open questions" collected together and discussed comparing the actual international medical literature.

This thesis contains four essays that analyze the behaviors that evolve when populations of boundedly rational individuals interact strategically for a long period of time. Individuals are boundedly rational in the sense that their strategy choices are determined by simple rules of adaptation -- learning rules. Convergence results for general finite games are first obtained in a homogenous setting, where all populations consist either of stochastic imitators, who almost always imitate the most successful strategy in a sample from their own population's past strategy choices, or stochastic better repliers, who almost always play a strategy that gives at least as high expected payoff as a sample distribution of all populations' past play. Similar results are then obtained in a heterogeneous setting, where both of these learning rules are represented in each population. It is found that only strategies in certain sets are played in the limit, as time goes to infinity and the mutation rate tends to zero. Sufficient conditions for the selection of a Pareto efficient such set are also provided. Finally, the analysis is extended to natural selection among learning rules. The question is whether there exists a learning rule that is evolutionarily stable, in the sense that a population employing this learning rule cannot be invaded by individuals using a different rule. Monte Carlo simulations for a large class of learning rules and four different games indicate that only a learning rule that takes full account of hypothetical payoffs to strategies that are not played is evolutionarily stable in almost all cases. / Diss. Stockholm : Handelshögsk., 2001

L’objectif de cette thèse est d’analyser le dialogue cartésien La Recherche de la Vérité par la Lumière Naturelle au sujet d‘une corrélation entre lui et les Objections subis par Descartes à ses Méditations et leurs respectifs Réponses. L’hypothèse principale est que la Recherche a été influencée par les Objections et Réponses, ce qui la situe dans un moment tardif du corpus cartésien. L’étude de La Recherche de la Vérité et de sa relation avec les Règles pour la direction de l’esprit et le Discours de la Méthode, ainsi que l’enquête sur les principales interprétations qui voient la Recherche comme une œuvre d’une époque antérieure aux Méditations révèle qu’il n’y a pas des preuves suffisantes pour établir une proximité temporelle entre eux, ni d’arguments assez forts pour établir une de ces hypothèses au détriment des autres. La comparaison entre la Recherche et les Objections et Réponses, à son tour, montre qu’il y en effet dans la Recherche la présence constante d’éléments du débat suscité par les Méditations. Comme ces éléments ne viennent pas de l’esprit cartésien, mais de nombreux autres savants qui ont lu les Méditations, ils sont plus déterminants pour établir la datation de la Recherche que la comparaison avec n’importe quel autre écrit de Descartes. Toutefois, si les arguments philosophiques et textuels peuvent confirmer l’hypothèse que la Recherche a été influencée par les Objections et Réponses, à eux seuls ils ne sont pas en mesure de nous offrir une datation plus précise pour cette œuvre. Ainsi, il est nécessaire de recourir à l’analyse des arguments historiques et contextuels pour essayer de situer le dialogue dans un moment plus précis entre 1641 et 1650. Compte tenu principalement de la correspondance personnelle du philosophe et des événements marquants de cette période de sa vie, nous concluons que la date la plus probable se situerait entre 1646 et 1647. / The aim of this thesis is to analyze Descartes’ dialogue The Search for Truth by means of the Natural Light regarding a comparison between it and the Objections suffered by Descartes to his Meditations and their respective Replies. The main hypothesis is that the Recherche has been influenced by the Objections and Replies, which in turn puts this work in a late stage of the Cartesian corpus. The study of the Search for Truth and its relation to the Rules for the Direction of the Mind and the Discourse on the Method, as well as the investigation of the main interpretations that perceive the Search as a work of an earlier time to the Meditations, reveals that there is no sufficient evidence to establish a temporal proximity between them, and there are no strong enough arguments for establish these hypotheses to the detriment of others. The comparison between the Search and the Objections and Replies, on the other hand, shows that there are in the Search the constant presence of elements from the debate generated by the Meditations, such elements are more crucial to establish the dating of the Search than the comparison to any other written of Descartes, because they are not from the Cartesian mind, but of many other scholars who read their Meditations. Whereas the philosophical and textual arguments are able to confirm the hypothesis that the Search has been influenced by the Objections and Replies, alone they are not able to offer a more precise dating for this work. Thus, the analysis of historical and contextual arguments is necessary in order to locate the dialogue in a more precise time between 1641 and 1650. In view of the personal correspondence of the philosopher and the events that marked this period of his life, our conclusion is that the most likely date would be between 1646 and 1647. / Recherche de la Véritée de sua relação com as Regras para a orientação do espírito e com o Discurso do Método, bem como a investigação das principais interpretações que veem a Recherche como uma obra de um momento anterior às Meditações, revela que não há elementos suficientes para estabelecer uma proximidade temporal entre esses textos, tampouco há argumentos suficientemente fortes para estabelecer uma dessas hipóteses em detrimento das outras. A comparação entre a Recherchee as Objeções e Respostas, por sua vez, demonstra que de fato há no diálogo a presença constante de elementos provenientes do debate gerado pelas Meditações, elementos que, por não serem provenientes da mente cartesiana, mas de diversos outros sábios, são mais determinantes para estabelecer sua datação do que a comparação com qualquer outro escrito de Descartes. Contudo, se os argumentos filosóficos e textuais são capazes de nos confirmar a hipótese de que a Recherche tenha sido influenciada pelas Objeções e Respostas, sozinhos eles não são capazes de nos oferecer uma datação mais precisa para essa obra. Deste modo é necessário recorrer à análise dos argumentos históricos e contextuais para tentar situar o diálogo em um momento mais preciso entre 1641 e 1650. A partir principalmente da correspondência pessoal do filósofo e dos acontecimentos que marcaram esse período de sua vida, chegamos à conclusão de que a data mais provável seria entre 1646 e 1647.

La communauté en ligne (CEL) est une forme très répandue de transfert de connaissances spécialisées, où des usagers géographiquement dispersés peuvent constituer une communauté en partageant des idées, envoyant et affichant des messages, débattant de sujets et nouant des amitiés en ligne. Un des problèmes avec ces CEL est leur durabilité, car leur apparition et leur croissance initiale sont suivies d’une phase de stagnation où les usagers cessent d’afficher des commentaires, ce qui mène la communauté à mourir par manque d’activité. Tenter de prolonger la phase dynamique de croissance d’une CEL est un sujet pertinent pour tout administrateur de CEL. Une façon de maintenir le dynamisme d’une CEL est d’encourager les contributions.Ce courant de recherche se penche sur la façon dont les CEL peuvent prolonger leur phase dynamique, en considérant différents aspects, en particulier les mesures des contributions des usagers et la manière dont les nouveaux usagers d’une CEL se comportent. Je propose d’utiliser différentes mesures pour évaluer les contributions des usagers. Une des mesures pour identifier les contributeurs très actifs est une mesure bibliométrique non-invasive basée sur l’indice de Hirsch. Un autre aspect de cette recherche concerne la façon dont les nouveaux usagers se comportent et comment cela peut être expliqué par l’attachement préférentiel.Ce courant de recherche se penche sur la façon dont les CEL peuvent prolonger leur phase dynamique, en considérant différents aspects, en particulier les mesures des contributions des usagers et la manière dont les nouveaux usagers d’une CEL se comportent. Je propose d’utiliser différentes mesures pour évaluer les contributions des usagers. Une des mesures pour identifier les contributeurs très actifs est une mesure bibliométrique non-invasive basée sur l’indice de Hirsch. Un autre aspect de cette recherche concerne la façon dont les nouveaux usagers se comportent et comment cela peut être expliqué par l’attachement préférentiel. / The online community (OC) is a popular form of specialized knowledge transfer, where geographically dispersed users can for a community by sharing ideas, send and post messages, debate topics, and forge online friendships. One of the problems with OC’s is that they tend to have a life cycle, where there is the birth and growth of the OC but then there is a stagnant stage where users stop posting to the OC and the community eventually dies due to inactivity. Trying to extend the vibrant growth stage of an OC is a relevant topic for any administrator of an OC. One way that an OC can stay vibrant is to encourage contributions.This research stream will look at how OC’s can keep their vibrancy for a longer period of time, by looking at various aspects of OC’s such as measures of user contribution and how new users in an OC behave. I propose to use different measures to evaluate users contributions to an OC. One of these measures is a non-invasive bibliometric measure using the Hirsch-index methodology as a way to identify high-level contributors. Another stream of this research will look at how new users behave and how this might be explained by preferential attachment.