A basic model of hierarchical structure, expressed by simple, linear differential equations, shows that the pattern of population growth is essentially determined by conditions of redundancy in the sub-structure of individuals. There does not exist any possible combination between growth rate and accident rate that could balance population numbers and/or the level of redundancy within the population; all possible combinations either lead to extinction or to positive population growth with a decline of the fraction of individuals with redundant substructure. Declining (...) populations, however, can be held fluctuating between certain limits by periodic phases of sub-unit repair. These results are particularly pertinent to the population dynamics of diploid (polyploid) organisms. (shrink)

Volterra's (1926) equations for competition and predator-prey interactions are modified by introduction of root terms. A critical comparison with the original equations shows that the dynamic properties of the systems remain essentially alike, while the modification allows for explicit solution of the differential equations. Detailed solutions and numerical examples are given.

Streaming services for audiobooks and ebooks have grown rapidly in recent years. The shift in consumption patterns has transformed both reading and publishing. One visible change is the attraction and importance of backlist titles. The article investigates how the relationship between frontlist and backlist in the bestseller segment has developed, and discusses the shift in the power balance between the two. By examining large-scale consumer behaviour data from one of the key players in subscription-based digital bookselling – Storytel – we (...) track book consumption both in detail and at a structural level. Our results show that backlist titles are increasingly important for bestselling authors who continue to publish frontlist titles, especially for fiction written in series. Streaming services foster new types of book consumption behaviour thanks to a combination of technology, media, reading habits, and social change. (shrink)

Using Giddens’s structuration theory and empirical data from a study with social enterprise stakeholders, the article explores how social entrepreneurs and the structure co-create one another. We show that the development of the contemporary significance of social entrepreneurialism lies in a combination of complex context-specific structural forces and the activities of agents who initiate, demand, and impose change. Social entrepreneurs intentionally tackle social challenges, but their actions bring unintentional results, such as the transfer of state responsibilities onto communities. Direct outputs (...) of their activities introduce indirect outcomes, bringing wider changes in culture and policy. The evolving nature of entrepreneurship and a number of factors that interplay in time and space, and enable and constrain social entrepreneurs, confirm the applicability of Giddens’s theory in the field of social entrepreneurship. The originality of this article derives from revealing mechanisms that enable social entrepreneurs to emerge and reasons for structural change. We also build a “co-creation model of structure and agency” that can be used to “engineer” the process of social entrepreneurship. (shrink)

Les « Amazones de la terreur » est issu de la thèse de l’historienne Fanny Bugnon, La violence politique au prisme du genre à travers la presse française (1970-1994), dirigée par Christine Bard et soutenue en novembre 2011 à l’Université d’Angers. À la fin des années 1960, dans le sillage des mouvements étudiants, des groupes de lutte armée, anticapitalistes et anti-impérialistes, sont apparus presque simultanément en Europe, au Japon, et aux USA. Tous comprenaient un nombre élevé de femmes d...