During three consecutive years, monthly samples of zooplankton were taken in the lacustrine (dam) zone of Jurumirim (São Paulo, Brazil). The seasonal effect on basic limnological features (thermal regime, oxygen distribution, phytoplankton biomass, etc.) was also examined. The influence of the seasonality on the fluctuation of the zooplankton composition and abundance was not clearly detected (...

The pattern of fluctuation in the population size of Bulinus globosus and Biomphalaria pfeifferi, in their infection rates with Schistosoma haematobium/S. mattheei and S. mansoni, respectively, and in the cercarial population size as monitored using hamster immersions, was elucidated in streams in the temperate highveld region of Zimbabwe over a 27-month period during 1982-1984. The results rev...

1.0 Introduction Seasonal variations in production and sales are a well known fact in business. Seasonality refers to regular and repetitive fluctuation in a time series which occurs periodically over a span of less than a year. The main cause of seasonal variations in time series data is the change in climate. For example, sales of woolen clothes generally increase in winter season. Besides th...

BACKGROUND In bipolar disorder (BD), seasonality of symptoms is common and disturbances in circadian rhythms have been reported. OBJECTIVES We identified high-penetrance families in a geographically restricted area in Northern Fennoscandia and studied the seasonal variation of clinical symptoms among BD subjects and their healthy relatives. DESIGN We explored the clinical characteristics of...

BACKGROUND Birth weight is known to fluctuate with season of birth, however, there is little information about seasonal variation in neonatal anthropometric measures. AIMS The aim of this study was to examine seasonal fluctuations in birth weight and selected anthropometric measures. STUDY DESIGN AND SUBJECTS The birth weight of singletons born after at least 37 weeks gestation was extracte...

OBJECTIVES To examine whether a seasonal fluctuation exists with rheumatoid arthritis (RA) activity and to analyse seasonal effects of varying components that express disease activity in RA patients. METHODS A group of 1665 RA patients (mean age 57.2 yrs, mean disease duration 9.9 yrs) whose data were available for 10 consecutive phases from a large observational cohort study conducted at our...

BACKGROUND The Sahel is subject to seasonal hungry periods with increasing rates of malnutrition. In Northern Nigeria, there is no surveillance system and surveys are rare. The objectives were to analyse possible observational bias in a sentinel surveillance system using repeated mixed longitudinal/cross-sectional data and estimate the extent of seasonal variation. METHODS Thirty clusters wer...