In South America, the largest seasonal savanna region is the Brazilian cerrado. Our aim was to study temporal changes in some community descriptors, such as floristic composition, richness, species density, plant density, and cylindrical volume, in a seasonal cerrado, comparing it to a nearby hyperseasonal cerrado. In four different seasons, we placed randomly ten 1 m(2) quadrats in each vegeta...

BACKGROUND In animals, the circadian pacemaker regulates seasonal changes in behavior by transmitting a signal of day length to other sites in the organism. The signal is expressed reciprocally in the duration of nocturnal melatonin secretion, which is longer in winter than in summer. We investigated whether such a signal could mediate the effects of change of season on patients with seasonal a...

Understanding how risks to human health change as a result of seasonal variations in environmental conditions is likely to become of increasing importance in the context of climatic change, especially in lower-income countries. A multi-disciplinary approach can be a useful tool for improving understanding, particularly in situations where existing data resources are limited but the environmenta...

The vast majority of variability in the instrumental surface temperature record is at annual frequencies. Systematic changes in the yearly Fourier component of surface temperature have been observed since the midtwentieth century, including a shift toward earlier seasonal transitions over land. Here it is shown that the variability in the amplitude and phase of the annual cycle of surface tempe...

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...

Many of the observed species interactions embedded in ecological communities are not permanent, but are characterized by temporal changes that are observed along with abiotic and biotic variations. While work has been done describing and quantifying these changes, little is known about their consequences for species coexistence. Here, we investigate the extent to which changes of species compos...

A 10-year record (1985-1994) of output statistics from the European Centre for Medium-Range Weather Forecasts (ECMWF) model shows that profound seasonal changes in surface pressure take place over the Antarctic continent. The most pronounced changes occur during the periods straddling the brief Antarctic summer, from September to December and again from January to April. Surface pressures atop ...

4 The vast majority of variability in the instrumental surface temperature record is at annual 5 frequencies. Systematic changes in the yearly Fourier component of surface temperature 6 have been observed since the mid-20th century, including a shift towards earlier seasonal 7 transitions over land. Here it is shown that the variability in the amplitude and phase of 8 the annual cycle of surfac...

The solid Earth deforms elastically in response to variations of surface atmosphere, hydrology, and ice/glacier mass loads. Continuous geodetic observations by Global Positioning System (CGPS) stations and Gravity Recovery and Climate Experiment (GRACE) record such deformations to estimate seasonal and secular mass changes. In this paper, we present the seasonal variation of the surface mass ch...

OBJECTIVES Previous research has shown that the extreme cold and short day lengths of polar winters promote increased production and uptake of thyroid hormones, resulting in marked declines in free triiodothyronine (fT3). However, this "polar T3 syndrome" has been documented almost exclusively on small samples of male sojourners and little is known about seasonal changes in thyroid function amo...