BACKGROUND Previous studies estimating the fraction of transmissions from persons with primary HIV have not focused on the effects of switching sex role in male homosexual populations. Such behavioral fluctuations can increase the contribution of primary HIV in the overall population. METHODS We modeled HIV transmission with 8 compartments defined by 4 behavioral groups, with different anal-i...

By using a model of gene conversion for treating concerted evolution of multigene families, a theory for calculating the variances and covariances of identity coefficients has been developed. Six coefficients on triple identity and 15 coefficients on quadruple identity are needed. The variances and covariances are obtained from the quadruple identity coefficients and divided into within-populat...

We study the population profile in a simple discrete time model of population dynamics. Our model, which is closely related to certain “bit–string” models of evolution, incorporates competition for resources via a population dependent death probability, as well as a variable reproduction probability for each individual as a function of age. We first solve for the steady–state of the model in me...

Age gradient of the mechanism of stimulus-response conflict cost was investigated in a population-based representative sample of 291 individuals, covering the age range from 6 to 89 years. Stimulus-response conflict cost, indicated by the amount of additional processing time required when there is a conflict between stimulus and response options, follows a U-shaped function across the lifespan....