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Significant Seasonal Variation (significant + seasonal_variation)
Selected AbstractsSeasonal studies on the alginate and its biochemical composition I: Sargassum polycystum (Fucales), PhaeophyceaePHYCOLOGICAL RESEARCH, Issue 4 2003Sundararaju Jothi Saraswathi SUMMARY Investigations were made on the brown seaweed Sargassum polycystum C. Agardh collected from Rameswaram Coast, Tamil Nadu. The alginates extracted from ,leaf', ,stem' and entire thallus of S. polycystum were investigated for their viscosity and chemical constituents, namely ,-D-mannuronic acid (M-block), ,-L-guluronic acid (G-block) and alternating sequences of ,-D-mannuronic acid and ,-L-guluronic acid (MG-block) for six different seasons between August 1998 and November 1999. Significant seasonal variation (P< 0.05) was observed with high yield of alginate in February. The alginate extracted from the ,leaf' region showed a maximum yield whereas the ,stem' region exhibited maximum viscosity. The amount of G-block was found to be more than M- and MG-blocks in all the samples tested. The amount of G-block was high in ,stem' followed by leaf and entire thallus. A positive correlation was recorded between viscosity and G-block. Among the three alginates, the ratio of M/G was low in the ,stem' followed by ,leaf' and entire thallus. [source] Moderate Seasonality in Testis Function of Domestic CatREPRODUCTION IN DOMESTIC ANIMALS, Issue 5 2007S Blottner Contents Adult male domestic cats are known to produce sperm throughout the year, although sexual activity is influenced by geographical location. In the northern hemisphere, feral domestic cats reproduce usually between January and July. Thus, seasonality in testicular activity might be suggested. The aim of the present study was to investigate gametogene and endocrine activity of cat testis throughout the entire year. Testes and epididymides (n = 10,12 per month) were collected after castration. Spermatogenesis was quantified by assessment of testicular sperm per testis and by flow cytometric analysis of the cells with different DNA content. Sperm from cauda epididymis were evaluated according to motility and morphological integrity. Testicular testosterone concentration was determined by enzyme immunoassay. Testis mass and sperm production varied moderately throughout the year. Significant seasonal variations were observed in the proportion of cells in the G2/M phase of cell cycle (p = 0.004) and the meiotic transformation (ratio of haploid : tetraploid cells; p = 0.021). Changes in testicular testosterone concentration were more pronounced and showed periods with high (spring) and significantly reduced testosterone levels (autumn). A marked seasonal alteration (p < 0.001) with a peak in March was assessed in the percentage of progressively motile sperm. The proportion of morphological intact sperm was also significantly higher in spring compared with winter time (p < 0.001). In conclusion, the study suggests moderate seasonal changes in quantity of sperm, more pronounced annual variation in hormone production and a distinct seasonal influence on functional sperm parameters in domestic cat. [source] Seasonal changes in acute toxicity of cadmium to amphipod Corophium volutatorENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2000Belinda J. Kater Abstract In vivo bioassays are frequently used to assess the ecotoxicological risks of contaminated sediments. For quality assurance purposes, these bioassays are accompanied by reference toxicity tests. For the bioassay with Corophium volutator, this reference toxicity test is an acute water-phase test with cadmium. Approximately 80 water-phase tests were conducted in the period 1991,1998. Corophium volutator shows a significant seasonal variation in response to cadmium, with a high LC50 in the winter period and a low LC50 in the summer period. Same variation can be found if Corophium is held in the laboratory instead of freshly collected in the field and if synthetic water is used instead of natural filtered seawater. The observed seasonal variation is not caused by the fact that the organisms are collected in the field or by the variation in seawater used for the water-phase tests. [source] Seasonal variations in [3H]citalopram platelet binding between healthy controls and violent offenders in FinlandHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 7 2005James Callaway Abstract Monthly binding densities (Bmax) of [3H]citalopram to the platelet serotonin transporter (SERT) was measured longitudinally over 1 year in a control group of 18 healthy Finnish male volunteers. Single platelet samples were also analysed from 33 men who were incarcerated for violent crimes during the same calendar year. A statistically significant seasonal variation in SERT Bmax was observed in both data sets, and bi-monthly floating averages for SERT Bmax were calculated and then fit to an annual sinusoidal curve for both groups. The Bmax for platelet [3H]citalopram binding showed a statistically significant (p,=,0.001) seasonal variance between a winter (January,February) maximum of 1590 fmol/mg protein and a summer (July,August) minimum of 1216 fmol/mg protein for the control group, with an R2 of 70% for the annual sinusoidal curve fit. A statistically significant (p,=,0.007) seasonal variance was also observed between a winter (January,February) maximum of 1980 fmol/mg protein and an autumnal (August,September) minimum of 1234 fmol/mg protein for the violent offenders, again with an R2 of 70% for the annual sinusoidal curve fit. This observation lends additional support to the idea that violent human behavior and impulsivity may be directly linked to values of SERT Bmax, which can be affected by various psychoactive drugs and also varies with the natural change of seasons. Copyright © 2005 John Wiley & Sons, Ltd. [source] Is season important for the diagnosis of cutaneous melanoma in southern Brazil?INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 1 2010A 10-year hospital-based study Background, Exposure to sunlight is an important etiologic factor in cutaneous melanoma (CM). In several countries, more cases of CM are diagnosed in summer than in winter. Aim, To analyze whether there is seasonal variation in the diagnosis of CM in southern Brazil. Methods, Data were collected from a hospital-based registry, including all cases of CM diagnosed between 1996 and 2005. Summer to winter and spring to fall ratios were used for the analysis, and a 95% confidence interval (CI) was calculated using Poisson regression. Results, Two hundred and eighty-one patients were diagnosed in this period. Although some months were shown to have higher absolute numbers of diagnosed melanomas (April, July, and January), there was no statistically significant seasonal variation in most of the melanomas in terms of either the summer to winter ratio [odds ratio (OR) = 1.09; 95% CI, 0.77,1.44] or spring to autumn ratio (OR = 1.01; 95% CI, 0.71,1.43). Only the number of lentigo maligna melanomas (LMMs) diagnosed in summer was higher than that in winter (OR = 2.83; 95% CI, 1.07,8.78). Conclusions, In southern Brazil, CMs do not seem to be more frequently diagnosed in summer than in winter. Darkening of melanocytic lesions and increased awareness of skin lesions during the summer could be possible explanations for LMMs being more frequently diagnosed in summer than in winter in this sample. [source] Freezing height distribution in the tropicsINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 6 2003Merhala Thurai Abstract The calculation of fade margins required to meet the user-specified availability criteria needs to take into consideration a number of meteorological factors specific to the earth-station location. One such factor is the annual average of the freezing level height. Information on this height is available in ITU-R Recommendation P. 839-3, which provides contours that are generated on a 1.5° by 1.5° latitude by longitude resolution grid. This paper compares these heights with the bright-band heights (BBH) obtained from the precipitation radar on-board the TRMM (Tropical Rainfall Measuring Mission) satellite. Four years of TRMM radar data have been analysed, and their averages are compared within the latitude range covered by the satellite orbit (35°N to 35°S). Comparisons show that the radar bright-band heights typically occur 300 m below the 0°C isotherm heights. However, results also indicate that this difference may be latitude dependent. Also examined are the year-to-year variability and the seasonal variation. In the former case, only 1998 showed BBH values which are somewhat higher in tropical regions, this year having had one of the strongest El Niño events recorded. In the latter case, results show significant seasonal variation, becoming more pronounced at higher latitudes. Copyright © 2003 John Wiley & Sons, Ltd. [source] Renal sexual segment of the Cottonmouth snake, Agkistrodon piscivorous (Reptilia, Squamata, Viperidae)JOURNAL OF MORPHOLOGY, Issue 6 2008David M. Sever Abstract The seasonal variation of the renal sexual segment (RSS) of males of the Cottonmouth snake, Agkistrodon piscivorous, is described using light and electron microscopy. This study is the first to describe the ultrastructure of the RSS of a viper (Viperidae) and only the fourth on a snake. Renal sexual segments from males collected February to May and from August to November are similar in appearance. The cells are eosinophilic and react with periodic acid/Schiff procedure (PAS) for neutral carbohydrates and bromphenol blue (BB) for proteins. At the ultrastructure level, the cells contain large (2 ,m diameter), electron-dense secretory granules and smaller vesicles with a diffuse material, and these structures abut against the luminal border and upon clear vacuoles continuous with intercellular canaliculi. Evidence was found for both apocrine and merocrine processes of product release. In June and July, the RSS are significantly smaller in diameter, largely basophilic, and have only scattered granules that are PAS+ and BB+. Cytologically, the RSS from June to July lack electron-dense secretory granules and the smaller vesicles with diffuse material. Numerous condensing vacuoles and abundant rough endoplasmic reticulum, however, indicate that active product synthesis is occurring. This is the first report of significant seasonal variation in the histology and ultrastructure of the RSS of a snake, although such reports exist for lizards. The seasons when the RSS is most highly hypertrophied correspond to the fall and spring mating seasons of A. piscivorous, as determined by other studies. J. Morphol., 2008. © 2007 Wiley-Liss, Inc. [source] Variations of diet composition of Red Deer (Cervus elaphus L.) in EuropeMAMMAL REVIEW, Issue 3-4 2001Claudia Gebert ABSTRACT To define the food resources of Red Deer (Cervus elaphus L.) in Europe and to detect the principal sources of variations in their diet, we reviewed field studies based on stomach content analysis. The study areas were classified into three main habitat groups (mixed-coniferous forest, mixed-deciduous forest, moorland), the food items into 13 plant categories, and we used five seasonal classes (winter, spring, summer, autumn, hunting season) for analysing the data set. For statistical analyses we used correspondence analysis and analysis of variance. Red Deer eat a varied diet comprising at least 145 plant species. The main sources of diet variation were due to habitat, leading us to identify three habitat types characterized by the consumption of a few key species. Clear seasonal variation was observed only for the seed and fruit items which were used mainly during the hunting season. Our results confirm that Red Deer can be classified among the intermediate feeders, with a mixed diet of grass & sedges (29%) and concentrate food items (63%). However, they also show Red Deer to be primarily a concentrate feeder (max. 75%) with no significant seasonal variation between the quantities of grass or sedges and concentrate food in the diet. In the light of these results, we discuss potential competition with other sympatric ungulates (wild and domestic). We suggest that it may be useful to take into account key food resources in modelling population dynamics and in taking management decisions. [source] A baseline biological survey of the proposed Taputeranga Marine Reserve (Wellington, New Zealand): spatial and temporal variability along a natural environmental gradientAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 2 2009Anjali Pande Abstract 1.Four macroalgal, four macroinvertebrate and eight fish species were surveyed at eight sites (three inside, five outside the proposed reserve) over three years before the establishment of the Taputeranga Marine Reserve (MR) on Cook Strait (Wellington, New Zealand). This baseline data set was used to estimate temporal and spatial variability in size and abundance of these taxa, and will be used to quantify taxon-specific changes in size and abundance once the MR is established. 2.Statistically significant differences in size and/or abundance were observed for many taxa among the sites. These differences are consistent with the existence of a natural environmental gradient from the west (entrance to Cook Strait) to the east (Wellington Harbour). This gradient highlights the importance of conducting a pre-reserve baseline survey at multiple sites and over multiple years to better understand the conservation or fisheries benefits that MRs are expected to deliver. 3.Two macroalgal, one macroinvertebrate, and six fish species showed statistically significant seasonal variation in abundance. Subsequent multi-taxa monitoring needs to include a seasonal component to capture this natural variability. 4.This multi-site and multi-year data set represents one of the most comprehensive and robust baseline data sets available anywhere in the world. It will be used to quantify the ecological changes associated with a newly established full no-take marine reserve. Ongoing monitoring will enhance understanding of the sizes and abundances of key taxa, allow a detailed determination of the conservation effects of reserve establishment, and inform management decisions for Wellington's south coast. Copyright © 2008 John Wiley & Sons, Ltd. [source] Admission rates of bipolar depressed patients increase during spring/summer and correlate with maximal environmental temperatureBIPOLAR DISORDERS, Issue 1 2004Avraham Shapira Objective:, We intended to identify a relationship, if exists, between various climatic factors and the admission rates of bipolar affective disorder depressed patients (BPD) or major depressive disorder patients (unipolar) (UPD) to psychiatric hospitals, as well as potential seasonal variability in hospitalization rates of this population. Methods:, Data on admissions of ICD-9 BPD and UPD patients to Tel Aviv's seven public psychiatric hospitals during 11 consecutive years were collected along with concomitant meteorological information Results:, Admissions of 4117 patients with BPD and 1036 with UPD who fulfilled our specific inclusion criteria were recorded. Bipolar depressed, but not UPD, patients exhibited significant seasonal variation (higher spring and summer versus winter mean monthly admission rates), and the admission rates of patients with BPD, but not UPD, correlated significantly with mean maximal monthly environmental temperature Conclusions:, Increased environmental temperature may be a risk factor for evolvement of major depressive episode in patients with bipolar disorder with psychiatric co-morbidity, at least in cases that necessitate hospitalization and at the examined geographic/climatic region of Israel. Further large-scale studies with bipolar depressed patients with and without co-morbid disorders are needed to substantiate our findings and to determine the role of seasonal and climatic influence on this population, as well as its relationship to the pathophysiology of bipolar disorder. [source] | |||||||||||||