This paper tests whether atmospheric brightness is related to Canadian birth seasonality ten-eleven months earlier. Births and visibility (brightness) are correlated nation-wide and in nine provinces/ cities. For the national correlation, r=0.928. Therefore, seasonal brightness provides a plausible explanation for inter-annual changes in seasonality, and may reconcile divergent viewpoints. Easy...

We consider a SIRS model with time dependent transmission rate. We assume time dependent vaccination which confers the same immunity as natural infection. We study two types of vaccination strategies: (i) optimal vaccination, in the sense that it minimizes the effort of vaccination in the set of vaccination strategies for which, for any sufficiently small perturbation of the disease free state,...

Seasonal declines in avian clutch size are well documented, but seasonal variation in other reproductive parameters has received less attention. For example, the probability of complete brood mortality typically explains much of the variation in reproductive success and often varies seasonally, but we know little about the underlying cause of that variation. This oversight is surprising given t...

Violence is widespread throughout the natural world, prominent examples being predatory violence between species, seasonal violent competition for mating rights and territories within species and food competition both within and between species. These interactions are generally between unrelated individuals with no social connection. There are, however, examples of violent behaviour which occur...

In healthy subjects, both the duration of wakefulness and the circadian pacemaker have been demonstrated to be involved in the regulation of mood. Some features of affective disorders suggest that these two factors also play a role in the dysregulation of mood. In particular, disturbances of the circadian pacemaker have been proposed to be a pathogenetic factor in Seasonal Affective Disorder, w...

Both influenza and respiratory syncytial virus (RSV) are active throughout the year in subtropical or tropical regions, but few studies have reported on age-specific seasonal patterns of these viruses. We examined the age-specific epidemic curves of laboratory-confirmed cases of influenza A (subtyped into seasonal A(H1N1), A(H3N2), and pandemic virus A(H1N1)pdm09), influenza B and respiratory s...

Use of scasonal climnte forecasts is ;1 rapidly evolving arca. Effective rcscarch and npplication of climate forecasts require close cooperation between scientists i n diverse disciplines and decision makers. Successful collaboration requires all players to at least partially uilderstand each other's perspective%. Issues associated with seasonal forecasts, through a selected review of both phys...

For organisms in seasonal environments, individuals that breed earlier in the season regularly attain higher fitness than their late-breeding counterparts. Two primary hypotheses have been proposed to explain these patterns: The quality hypothesis contends that early breeders are of better phenotypic quality or breed on higher quality territories, whereas the date hypothesis predicts that seaso...

Seasonal declines of fitness-related traits are often attributed to environmental effects or individual-level decisions about reproductive timing and effort, but genetic variation may also play a role. In populations of Pacific salmon (Oncorhynchus spp.), seasonal declines in reproductive life span have been attributed to adaptation-by-time, in which divergent selection for different traits occ...

Pesticide safety training is mandated for migrant and seasonal farmworkers. However, none is required for family members, who implement home sanitation to protect against pesticide exposure and need to control pests in substandard housing. Controlled studies have demonstrated the efficacy of pesticide education programs for farmworker families, but no carefully evaluated demonstration projects ...