Seasonal polyphenisms are widespread in nature, yet the selective pressures responsible for their evolution remain poorly understood. Previous work has largely focussed either on the developmental regulation of seasonal polyphenisms or putative 'top-down' selective pressures such as predation that may have acted to drive phenotypic divergence. Much less is known about the influence of seasonal ...

The dynamics of circadian rhythms needs to be adapted to day length changes between summer and winter. It has been observed experimentally, however, that the dynamics of individual neurons of the suprachiasmatic nucleus (SCN) does not change as the seasons change. Rather, the seasonal adaptation of the circadian clock is hypothesized to be a consequence of changes in the intercellular dynamics,...

Non-or semiparametric estimation and lag selection methods are proposed for three seasonal nonlinear autoregressive models of varying seasonal exibility. All procedures are based on either local constant or local linear estimation. For the semipara-metric models, after preliminary estimation of the seasonal parameters, the function estimation and lag selection are the same as nonparametric esti...

The locally migratory behavior of the high arctic muskox (Ovibos muschatus) is a central component of the breeding and winter survival strategies applied to cope with the highly seasonal arctic climate. However, altered climate regimes affecting plant growth are likely to affect local migration dynamics of the muskox. In this study, we apply longterm local-scale data on the seasonal distributio...

BACKGROUND In Lithuania, suicides are a grave public health problem, requiring more extensive investigation. The aim of the study was to assess the seasonal variations of suicides in Lithuania throughout the years 1993-2002, describing patterns by gender, age and method of suicide. METHODS The study material consisted of all registered suicides (n = 16,147) committed throughout 1993-2002 in L...

The seasonality of physical, chemical, and biological water variables is a major characteristic of temperate, dimictic lakes. Yet, few investigations have considered the potential information that is encoded in seasonal dynamics with respect to the paleolimnological record. We used a one-year sequence of diatoms obtained from sediment traps and water samples, as well as the sedimentary diatom r...

Pigment-based chemotaxonomy and CHEMTAX software have proven to be a valuable phytoplankton monitoring tool in marine environments, but are yet underdeveloped to determine algal assemblages in freshwater ecosystems. The main objectives of this study were (1) to compare the results of direct microscopy and CHEMTAX in describing phytoplankton community composition dynamics in a large, shallow and...

The Wiener-Kolmogorov (WK) signal extraction filter, extended to handle nonstationary signal and noise, has minimum Mean Square Error (MSE) among filters that preserve the signal’s initial values; however, the stochastic dynamics of the signal estimate typically differ substantially from that of the target. The use of such filters, although widespread, is observed to produce dips in the spectru...

Periodic time series analysis refers to the modelling approach where important time series properties depend on the period of the year. The standard approach to time series modelling is to treat a time series as a stochastic process with seasonal fluctuations. In a periodic analysis seasonal variations are modelled using separate yearly time series for each season, which do not possess seasonal...