Traditional cost-effectiveness analysis (CEA) assumes that program costs and benefits scale linearly with investment-an unrealistic assumption for epidemic control programs. This paper combines epidemic modeling with optimization techniques to determine the optimal allocation of a limited resource for epidemic control among multiple noninteracting populations. We show that the optimal resource allocation depends on many factors including the size of each population, the state of the epidemic in each population before resources are allocated (e.g. infection prevalence and incidence), the length of the time horizon, and prevention program characteristics. We establish conditions that characterize the optimal solution in certain cases.

Two studies examined age differences in recall and recognition memory for positive, negative, and neutral stimuli. In Study 1, younger, middle-aged, and older adults were shown images on a computer screen and, after a distraction task, were asked first to recall as many as they could and then to identify previously shown images from a set of old and new ones. The relative number of negative images compared with positive and neutral images recalled decreased with each successively older age group. Recognition memory showed a similar decrease with age in the relative memory advantage for negative pictures. In Study 2, the largest age differences in recall and recognition accuracy were also for the negative images. Findings are consistent with socioemotional selectivity theory, which posits greater investment in emotion regulation with age.