In this study we examined whether the well-known winter excess of schizophrenic births exists among Dutch schizophrenia patients when statistical artifacts such as the age-incidence and age-prevalence effects are avoided and, if so, whether the seasonal preovulatory release of overripe ovum (SPrOO) hypothesis, that is, seasonally bound ovopathy, might be an explanation for this excess. We analy...

We extend a previous Gause-type predator–prey model to include a general monotonic and bounded seasonally varying functional response. The model exhibits rich dynamical behaviour not encountered when the functional response is not seasonally forced. A theoretical analysis is performed on the model to investigate the global stability of the boundary equilibria and the existence of periodic solut...

The critical domain size problem determines the size of the region of habitat needed to ensure population persistence. In this paper we address the critical domain size problem for seasonally fluctuating stream environments and determine how large a reach of suitable stream habitat is needed to ensure population persistence of a stream-dwelling species. Two key factors, not typically found in c...

Several recent studies show that seasonal variation and cyclical variation in unemployment are correlated. A common nding is that seasonality tends to diier across the business cycle stages of recessions and expansions. Since seasonal adjustment methods assume that the two sources of variation can somehow be separated, the present study examines the impact of seasonal adjustment on the analysis...