A framework for the statistical analysis of counts from infectious disease surveillance databases is proposed. In its simplest form, the model can be seen as a Poisson branching process model with immigration. Extensions to include seasonal effects, time trends and overdispersion are outlined. The model is shown to provide an adequate fit and reliable one-step-ahead prediction intervals for a typical infectious disease time series. In addition, a multivariate formulation is proposed, which is well suited to capture space-time dependence caused by the spatial spread of a disease over time. An analysis of two multivariate time series is described. All analyses have been done using general optimization routines, where ML estimates and corresponding standard errors are readily available.

Summary 1.The growing interest in the effects of light pollution on daily and seasonal cycles of animals has led to a boost of research in recent years. In birds, it has been hypothesized that artificial light at night can affect daily aspects of behaviour, but one caveat is the lack of knowledge about the light intensity that wild animals, such as birds, are exposed to during the night. 2. Organisms have naturally evolved daily rhythms to adapt to the 24-h cycle of day and night, thus, it is important to investigate the potential shifts in daily cycles due to global anthropogenic processes such as urbanization. 3. We captured adult male European blackbirds (Turdus merula) in one rural forest and two urban sites differing in the degree of anthropogenic disturbance. We tagged these birds with light loggers and simultaneously recorded changes in activity status (active/non-active) through an automated telemetry system. We first analysed the relationship between light at night, weather conditions and date with daily activity onset and end. We then compared activity, light at night exposure and noise levels between weekdays and weekends. 4. Onset of daily activity was significantly advanced in both urban sites compared to the rural population, while end of daily activity did not vary either among sites. Birds exposed to higher amounts of light in the late night showed earlier onset of activity in the morning, but light at night did not influence end of daily activity. Light exposure at night and onset/end of daily activity timing was not different between weekdays and weekends, but all noise variables were. A strong seasonal effect was detected in both urban and rural populations, such as birds tended to be active earlier in the morning and later in the evening (relative to civil twilight) in the early breeding season than at later stages. 5. Our results point at artificial light at night as a major driver of change in timing of daily activity. Future research should focus on the costs and benefits of altered daily rhythmicity in birds thriving in urban areas.

Fusion of biological membranes is mediated by distinct integral membrane proteins, e.g., soluble N-ethylmaleimide-sensitive factor attachment protein receptors and viral fusion proteins. Previous work has indicated that the transmembrane segments (TMSs) of such integral membrane proteins play an important role in fusion. Furthermore, peptide mimics of the transmembrane part can drive the fusion of liposomes, and evidence had been obtained that fusogenicity depends on their conformational flexibility. To test this hypothesis, we present a series of unnatural TMSs that were designed de novo based on the structural properties of hydrophobic residues. We find that the fusogenicity of these peptides depends on the ratio of ␣-helix-promoting Leu and ␤-sheet-promoting Val residues and is enhanced by helix-destabilizing Pro and Gly residues within their hydrophobic cores. The ability of these peptides to refold from an ␣-helical state to a ␤-sheet conformation and backwards was determined under different conditions. Membrane fusogenic peptides with mixed Leu͞ Val sequences tend to switch more readily between different conformations than a nonfusogenic peptide with an oligo-Leu core. We propose that structural flexibility of these TMSs is a prerequisite of fusogenicity.