Biological phenomena offer a rich diversity of problems that can be understood using mathematical techniques. Three key features common to many biological systems are temporal forcing, stochasticity and nonlinearity. Here, using simple disease models compared to data, we examine how these three factors interact to produce a range of complicated dynamics. The study of disease dynamics has been a...

Cycles in biological populations have been shown to arise from enemy-victim systems, delayed density dependence, and maternal effects. In an initial effort to model the year-to-year dynamics of natural populations of entomopathogenic nematodes and their insect hosts, we find that a simple, nonlinear, mechanistic model produces large amplitude, period two population cycles. The cycles are genera...

We present a phylogenetic study of black fungi in lichens, primarily focusing on saxicolous samples from seasonally arid habitats in Armenia, but also with examples from other sites. Culturable strains of lichen-associated black fungi were obtained by isolation from surface-washed lichen material. Determination is based on ITS rDNA sequence data and comparison with published sequences from othe...

At ultraviolet wavelengths the albedo of most natural surfaces is small with the striking exception of snow and ice. Therefore, snow cover is a major challenge for various applications based on radiative transfer modelling. The aim of this work was to determine the characteristic effective UV range surface albedo of various land cover types when covered by snow. First we selected 1 by 1 degree ...

Additional baseline parameter values appear in Table S1, along with literature sources [1–12]. We assumed a Susceptible-Infected-Recovered-Vaccinated-Susceptible (SIRVS ) natural history and voluntary vaccination. A susceptible individual becomes infected (S → I) by a single infectious contact with probability p(t) per day, which varies seasonally. The seasonality probability of transmission is...

This study has compared the environmental characteristics of the basins and saline lower reaches of the tributaries of eight estuaries on the south coast of Western Australia, which differ in their degree of connectivity with the ocean. Although four estuaries between 115.1° and 121.8° E along that coast remain permanently open to the ocean, the others only become open when the volume of river ...

Status signals allow competitors to assess each other's resource holding potential and reduce the occurrence of physical fights. Because status signals function to mediate competition over resources, a change in the strength of competition may affect the utility of a status signaling system. Status signals alter competitor behavior during periods of high competition, and thus determine access t...

Increases in invasive Streptococcus pyogenes and S. pneumoniae above the seasonally expected levels are currently being seen in England. Preliminary analyses suggest that the high level of influenza activity seen this winter may be contributing to an increased risk of concurrent invasive bacterial and influenza infections in children and young adults.

Glucocorticoid hormones like corticosterone (CORT) play essential metabolic roles at both baseline and stress-induced concentrations, and CORT titers vary seasonally in patterns occurring across many different vertebrate species. It has been hypothesized that CORT may vary seasonally due to changing energy requirements at different times of year. However, hormone effects are dependent on bindin...

Whether precooling is beneficial for exercise performance in warm climates when heat acclimatised is unclear. The purpose of this study was to determine the effect of precooling on repeat-sprint performance during a simulated team-sport circuit performed outdoors in warm, dry field conditions in seasonally acclimatised males (n = 10). They performed two trials, one with precooling (PC; ice slus...