An SEI autonomous model with logistic growth rate and its corresponding nonautonomous model are investigated. For the autonomous case, we give the attractive regions of equilibria and perform some numerical simulations. Basic demographic reproduction number R d is obtained. Moreover, only the basic reproduction number R 0 cannot ensure the existence of the positive equilibrium, which needs addi...

As educational institutions continue to explore e-learning alternatives and as people continue to choose e-learning over traditional programs, additional empirically-supported research is required to understand the impacts and implications of e-learning. The objective of this study was to investigate the role of age and efficacy on computer usage behaviors and attitudes. The Technology Acceptan...

We study a two dimensional version of Neuhauser’s long range sexual reproduction model and prove results that give bounds on the critical values λ f for that the process to survive from a finite set and λe for the existence of a nontrivial stationary distribution. Our first result comes from a standard block construction, while the second involves a comparison with the “generic population model...

We are concerned with an epidemic in a closed population under the assumption that the per capita number of contacts remains constant, when population size diminishes due to the fatal consequences of the disease. We focus on the nal size as a function of the basic reproduction ratio R0 (which now is independent of population size!) and the survival probability f. Mathematically the model is des...

Recently, a unique case of hybridogenesis at a social level was reported in local populations of the desert ants Cataglyphis. Queens mate with males originating from a different genetic lineage than their own to produce hybrid workers, but they use parthenogenesis for the production of reproductive offspring (males and females). As a result, non-reproductive workers are all inter-lineage hybrid...

An enduring problem in evolutionary biology is the near ubiquity of sexual reproduction despite the inherent cost of transmitting only half the parent's genes to progeny. Queens of some ant species circumvent this cost by using selectively both sexual reproduction and parthenogenesis: workers arise from fertilized eggs, while new queens are produced by parthenogenesis. We show that queens of th...

The near-ubiquity of sexual reproduction in animal species has long been considered a paradox because sexually reproducing individuals transmit only half of their genome to their progeny. Here, we show that the ant Cataglyphis cursor circumvents this cost by using alternative modes of reproduction for the production of reproductive and nonreproductive offspring. New queens are almost exclusivel...

Cellular life requires the presence of a set of biochemical mechanisms in order to maintain a predictable process of growth and division. Several attempts have been made towards the building of minimal protocells from a top-down approach, i.e. by using available biomolecules. This type of synthetic approach has so far been only partially successful, and appropriate models of the synthetic proto...

Individuals who reproduce asexually have a two-fold advantage over their sexually-reproducing counterparts as they are able to reproduce twice as fast. Explaining why sexual reproduction is favoured over asexual reproduction therefore remains an important challenge in evolutionary biology. Various mechanisms involving resistance to parasites, adaptation to novel environments and helping to purg...