In this paper, we look at the betweenness centrality of ego in an ego network. We discuss the issue of normalization and develop an efficient and simple algorithm for calculating the betweenness score. We then examine the relationship between the ego betweenness and the betweenness of the actor in the whole network. Whereas, we can show that there is no theoretical link between the two we under...

This study was performed to evaluate the applicability of the ego-integrity model for home residing elderly to elderly patients in long-term care hospitals. In order to identify the predictors of ego-integrity in elderly patients, a regression analysis was conducted. Results showed that higher age, lower pain levels, higher levels of fantasy and perspective taking, and lower personal distress l...

In an environment of anonymous random matching, Kandori [1992] showed that with a sufficiently rich class of simple information systems the folk theorem holds. We specialize to a gift-giving game and examine the stochastic stability of a process of learning and evolution in this setting. If the benefit of future altruism is too small, then there is no altruism. When the benefit of altruism is l...

Game theory is based on the assumption that individuals act according to self-interest and make decisions that maximize their personal payoffs. To test this fundamental assumption, we conducted a survey study in the context of influenza vaccination decisions. Contrary to the assumption of self-interest, we found that altruism plays an important role in vaccination decisions. Nevertheless, altru...

Hamilton's theory of inclusive fitness showed how natural selection could lead to behaviors that decrease the relative fitness of the actor and also either benefit (altruism) or harm (spite) other individuals. However, several fundamental issues in the evolution of altruism and spite have remained contentious. Here, we show how recent work has resolved three key debates, helping clarify how Ham...

Many thought Darwinian natural selection could not explain altruism. This error led Wynne-Edwards to explain sustainable exploitation in animals by selection against overexploiting groups. Williams riposted that selection among groups rarely overrides within-group selection. Hamilton showed that altruism can evolve through kin selection. How strongly does group selection influence evolution? Fo...