Seasonal Variation of Suicide in Brazil

Most of what is known about the seasonal variation in suicide rate originates from studies conducted in the northern hemisphere; very few studies have been done in the southern hemisphere. The purpose of the present study was to explore the possibility that in Brazil, the seasonal variation of suicides is a function of photoperiod. This was accomplished by analyzing monthly suicide data for a 12 yr period (1979 to 1990), within latitudes ranging from 2°N to 33°S. Single cosinor analyses with periods of 12 or 6 months were applied to time series of monthly total and suicidal deaths, separated by gender and state. Significant spring or early summer peaks of suicide were found only in the south of Brazil for both men and women, except for the latter in one state. These peaks did not coincide with those found for total deaths, which occurred in the autumn or winter in all areas. No significant six‐month period was found. In the present study, the chance of a suicide was typically 10–17% higher during the peak period than during the other months of the year. Although this moderate seasonal effect might not be sufficient to justify planning large scale prophylactic interventions, those dealing with patients who have suicide ideation should be aware of this high risk time.     

Seasonal Variation in Pathogenicity of Phytophthora infestans

During a four year study it was shown that the mean lesion area (M.L.A.) developed on leaflets of different potato cultivars by isolates of P. infestans after artificial inoculation varied periodically during the year. Disease symptoms observed changed from pinpoint necroses to regular sporulating lesions depending on the season and the cultivar. Analysis of variance revealed that differences in lesion size between experiments performed in different seasons were significant. The largest M.L.A. was found in late spring or in autumn but autumnal increase of M.L.A. was usually significantly lower than that in spring. Periodicity of M.L.A. was accompanied by a similar phenomenon in sporulation density of P. infestans isolates cultured in vitro. However, the peaks of sporulation, in comparison with peaks of M.L.A. appeared in different seasons. The highest disease level coincided with a decline in sporulation density of P. infestans cultured in vitro and the decrease of M.L.A. corresponded with an increase in sporulation density per cm² of medium. Variation in M.L.A. found in this study seemed not to be related to variability in plant reaction. In this connection a hypothesis has been proposed that the changes of M.L.A. were due to variation in pathogenicity of the fungus.     

Seasonal Variation in Sporulation of Phytophthora infestans

Sporulation ability of two isolates of Phytophthora infestans maintained on potato tuber slices of a susceptible cv. ‘Bintje’ and on-rye agar medium was studied for four years (1981–1984). This feature of the fungus was shown to vary in particular seasons during the year. Significantly higher sporulation density per cm² of aerial mycelium on potato tuber slices was observed in winter and late autumn while significantly lower sporulation was found in spring. Similar tendencies were observed when one of the isolates was cultivated on rye agar medium under controlled conditions. Positive correlation was found between sporulation patterns of isolates of the fungus maintained on rye agar and on tuber slices. Hypothesis has been proposed that these changes are due, to a biorhythm in the fungus.     

Seasonal Variation in Estimates of Cereal-ear Photosynthesis

The potential contribution by ear photosynthesis to yield ofwheat grain was estimated to be greater in summer than winterin glasshouse conditions, and to be light-dependent in controlledenvironment. These results offer an explanation for variationsin published results.     

Seasonal Variation in Human Salivary Cortisol Concentration

Measurement of cortisol concentration can contribute important information about an individual's ability to adjust to various environmental demands of both physical and psychosocial origin. However, one uncertainty that affects the possibilities of correctly interpreting and designing field studies is the lack of observations of the impact of seasonal changes on cortisol excretion. For this reason, the month‐to‐month changes in diurnal cortisol concentration, the awakening cortisol response (ACR), maximum morning concentration, and fall during the day were studied in a group of 24 healthy men and women 32 to 61 yrs of age engaged in active work. On one workday for 12 consecutive months, participants collected saliva at four time points for determination of cortisol: at awakening, +30 min, +8 h, and at 21:00 h. Data were analyzed by a repeated measures design with month (12 levels) and time‐of‐day (4 levels) as categorical predictors. Cortisol concentrations were analyzed on a log scale. The diurnal pattern of cortisol was similar across months (interaction between month and time of day: p>0.4). The main effects of month and time‐of‐day were statistically significant (p <0.001). Highest concentrations were observed in February, March, and April, and lowest concentrations were observed in July and August. There were no statistically significant effects in any of the other measures, or between men and women. In conclusion, a seasonal variation in salivary cortisol concentrations was detected in an occupationally active population. Thus, seasonal variation needs to be taken into account when designing and evaluating field studies and interventions and when making comparisons across studies.     

澳门死鸟数量的区域分布和季节变化

从2005年11月至2006年12月,共捡到死鸟866只.澳门地区所捡死鸟数量在各区域分布非常不均匀(F2,39=9.824, P=0.003),以澳门半岛发现的死鸟数量最多,占总数量的73.2%,而氹仔和路环发现的死鸟数量分别占总数量的14.3%和12.5%.澳门地区死鸟平均密度为3±0.5只/ km2·yr (1～6只/ km2·yr).死鸟在一年中的分布不均匀,以2～7月死鸟数量多,而8～12月死鸟少,但差异不显著(F13,28=0.598,P=0.825).每月死鸟总数量与月平均最高气温、月平均相对湿度相关(F2,11=5.466, P=0.022),回归方程是Y=3.624X1-4.321X2(X1=月平均湿度,X2=月平均最高气温).表明每月死鸟数量与月平均湿度正相关,即湿度越大、死亡的鸟数量越多;而与月平均最高气温负相关,即平均最高气温越高,鸟类死亡数量越少.鸟类死亡数量与风速和降雨量没有关系.分析认为,目前澳门地区死鸟平均密度可能被低估,但澳门半岛死鸟密度(61只/ km2·yr)基本能反映该环境下的野生鸟类死亡密度.     

Seasonal Variation in Low Density Lipoprotein Oxidation and Antioxidant Status

Accumulating evidence indicates that oxidative modification of low-density lipoproteins is atherogenic and that antioxidants may play a role in protection of LDL against oxidation. Several studies have reported a seasonal fluctuation in antioxidant levels, but to date nothing is known about seasonal fluctuations in parameters of oxidizability. We collected blood from 10 volunteers at four different periods over one year (February, May, September and December), and measured the amount of plasma lip ids, plasma antioxidants, lipid and fatty acid composition of the LDL particle, LDL antioxidant content, LDL particle size and oxidation parameters (lag time and propagation rate). No seasonal fluctuation for lag time and propagation rate of copper ion-induced LDL oxidation was found. Small seasonal fluctuations were observed for some determinants of LDL oxidation, e.g. plasma and LDL vitamin E and LDL particle size, and for plasma lipids, plasma and LDL lutein and LDL p-carotene. Fatty acid composition of LDL did not change during the year. The main determinant of oxidation susceptibility was the fatty acid composition of LDL. We conclude that LDL oxidation parameters do not change over the year.     

Age and Seasonal Variation in Serum Testosterone Concentration Among Men

Serum testosterone concentrations from 4.462 military veterans, ages 32-44, were examined for age and seasonal variation. Testosterone concentrations were assayed from a single serum sample from each subject. All samples were drawn before breakfast, at about 8:00 a.m., from subjects recruited over a 16-month study period. Mean levels declined with age (P less than .001), from 864 ng/dl at age 32 to 602 ng/dl at age 44. Mean levels also varied with month of testing (P less than .01), with a seasonal peak in December (the seasonal peak was in November for men in their early 30s). The age effect was greater than the seasonal effect. Both effects may bear upon behaviour and should be treated as possible sources of error in studies of testosterone.     

Seasonal Variation of Diurnal and Ultradian Rhythms in Red Deer

To describe the normal rhythmic behavioural patterns and to test procedures for the detection of short-time disturbances, 4 red deer were studied in 2 quasi-natural enclosures. Activity and feeding were recorded by means of the storage-telemetrysystem ETHOSYS®. Daily and monthly mean values, power spectra and 'Degrees of Functional Coupling' (DFC) were calculated. DFC were applied to measure stability and harmonic synchronisation between ultradian rhythms and the 24-hours period. The general patterns of activity and feeding were nearly identical in all animals and closely related to photoperiod change. Levels of total activity and feeding were lowest in winter and highest in summer. In winter highest activity was generally observed in daylight hours and shifted gradually to dark hours in summer. Spectral analysis of activity and feeding revealed a time pattern in which ultradian components, between 4.8 and 12 hrs in period length, mostly exceeded the diurnal rhythm power. Compared to winter higher frequencies were found in activity and feeding in spring, summer and autumn. During such periods up to 8 strong bouts of activity per day (3-hrs rhythm) were observed. These rhythmic patterns are discussed in the context of red deer feeding strategy. Short-term disturbances by humans and changing feeding conditions resulted in lowered DFCs. Time pattern analysis of long-term and continuously measured behavioural parameters proved to be an appropriate approach for observing general living conditions and for detecting disturbances.     

Seasonal Variation of Virioplankton in a Eutrophic Shallow Lake

Lake Donghu is a typical eutrophic freshwater lake in which high abundance of planktonic viruses was recently revealed. In this study, seasonal variation of planktonic viruses were observed at three different trophic sites, hypertrophic, eutrophic, and mesotrophic regions, and the correlation between their abundances and other aquatic environmental components, such as bacterioplankton, chlorophyll a, burst size, pH, dissolved oxygen, and temperature, was analyzed for the period of an year. Virioplankton abundance detected by transmission electron microscope (TEM) ranged from 5.48 × 10⁸ to 2.04 × 10⁹ ml⁻¹ in all the sites throughout the study, and the high abundances and seasonal variations of planktonic viruses were related to the trophic status at the sampled sites in Lake Donghu. Their annual mean abundances were, the highest at the hypertrophic site (1.23×10⁹ ml⁻¹), medium at the eutrophic site (1.19×10⁹ ml⁻¹), and the lowest at the mesotrophic site (1.02×10⁹ ml⁻¹). The VBR (virus-to-bacteria ratio) values were high, ranging from 49 to 56 on average at the three sampled sites. The data suggested that the high viral abundance and high VBR values might be associated with high density of phytoplankton including algae and cyanobacteria in this eutrophic shallow lake, and that planktonic viruses are important members of freshwater ecosystems.     

Seasonal Variation in Mate Choice of Photinus ignitus Fireflies

Mate choice by either sex may vary with changes in the associated costs and benefits, determined by factors such as the availability of potential mates and variation in mate quality. We examined seasonal variation in operational sex ratio, courtship behavior, spermatophore mass, egg count, and the relationship between morphological traits and mating success in Photinus ignitus fireflies to determine if mate choice in either sex varied with the availability and relative reproductive investment of fertilizable females and sexually active males. Successfully mating males had larger lanterns than unsuccessful males when the operational sex ratio was male‐biased. In addition, female responsiveness to male signals increased as the number of courting males decreased, and male spermatophore mass decreased with body size across the mating season. Successfully mating females had larger body mass than unsuccessful females. Female body mass predicted egg count and female rejection by males increased as the season progressed and female size decreased. These results suggest that both male and female P. ignitus exhibit mate choice, and that such choice is influenced by seasonal variation in the abundance and quality of potential mates.     

Seasonal Variation in the Occurrence of Acute Urinary Retention

Objective: To determine whether acute urinary retention shows a seasonal variation.

Methods: All acute urinary retentions observed in the emergency room of St. Anna Hospital, Ferrara, along an eight-year period (1991-1998) were considered. Diagnosis was made on the basis of history, physical examination, and bladder drainer by insertion of a catheter with registration of the retained urinary volume. The main determining cause of the acute urinary retention event was tentatively determined. Month and day of each event were categorized both by seasons and monthly intervals. For statistical analysis chi-square test for goodness of fit and partial Fourier series were used.

Results: 1,133 acute urinary retention events were observed in 929 different subjects (871 males, 58 females). In 738 cases it was possible to define the main determining cause of the event. The seasonal distribution showed a higher frequency peak of events in summer and autumn both for total population and males subgroup. Analysis by determining cause of the event demonstrated a greater frequency of events in summer only in patients with prostatic hypertrophy. Chronobiologic evaluation showed a circannual pattern for acute urinary retention, both for total sample and male subgroup, with a significant peak in late summer (August-September). Analysis by main determining cause revealed a similar circannual pattern only for cases of acute urinary retention determined by prostatic hypertrophy.

Conclusions: The present study shows that acute urinary retention exhibits a circannual distribution in its occurrence, particularly when caused by prostatic hypertrophy.     

Seasonal Variation of Dystocia in a Large Danish Cohort

Background

Dystocia is one of the most frequent causes of cesarean delivery in nulliparous women. Despite this, its causes are largely unknown. Vitamin D receptor (VDR) has been found in the myometrium. Thus, it is possible that vitamin D affects the contractility of the myometrium and may be involved in the pathogenesis of dystocia. Seasonal variation of dystocia in areas with distinct seasonal variation in sunlight exposure, like Denmark, could imply that vitamin D may play a role. This study examined whether there was seasonal variation in the incidence of dystocia in a Danish population.

Method

We used information from a cohort of 34,261 nulliparous women with singleton pregnancies, spontaneous onset of labor between 37 and 42 completed gestational weeks, and vertex fetal presentation. All women gave birth between 1992 and 2010 at the Department of Obstetrics and Gynecology, Aarhus University Hospital, Skejby. Logistic regression combined with cubic spline was used to estimate the seasonal variation for each outcome after adjusting for calendar time.

Results

No evidence for seasonal variation was found for any of the outcomes: acute cesarean delivery due to dystocia (p = 0.44); instrumental vaginal delivery due to dystocia (p = 0.69); oxytocin augmentation due to dystocia (p = 0.46); and overall dystocia (p = 0.91).

Conclusion

No seasonal variation in the incidence of dystocia was observed in a large cohort of Danish women. This may reflect no association between vitamin D and dystocia, or alternatively that other factors with seasonal variation and influence on the occurrence of dystocia attenuate such an association.     

Seasonal Variation in the Occurrence of Acute Urinary Retention

Objective: To determine whether acute urinary retention shows a seasonal variation. Methods: All acute urinary retentions observed in the emergency room of St. Anna Hospital, Ferrara, along an eight-year period (1991–1998) were considered. Diagnosis was made on the basis of history, physical examination, and bladder drainer by insertion of a catheter with registration of the retained urinary volume. The main determining cause of the acute urinary retention event was tentatively determined. Month and day of each event were categorized both by seasons and monthly intervals. For statistical analysis chi-square test for goodness of fit and partial Fourier series were used. Results: 1,133 acute urinary retention events were observed in 929 different subjects (871 males, 58 females). In 738 cases it was possible to define the main determining cause of the event. The seasonal distribution showed a higher frequency peak of events in summer and autumn both for total population and males subgroup. Analysis by determining cause of the event demonstrated a greater frequency of events in summer only in patients with prostatic hypertrophy. Chronobiologic evaluation showed a circannual pattern for acute urinary retention, both for total sample and male subgroup, with a significant peak in late summer (August–September). Analysis by main determining cause revealed a similar circannual pattern only for cases of acute urinary retention determined by prostatic hypertrophy. Conclusions: The present study shows that acute urinary retention exhibits a circannual distribution in its occurrence, particularly when caused by prostatic hypertrophy.     

美丽异木棉光合相关酶活性季节性变化

对美丽异木棉叶片叶绿素含量与乙醇酸氧化酶（GO）、核酮糖二磷酸羧化酶（RuBPCase）活性的季节变化进行测定。结果表明：叶片Chla、Chlb和Chl（a＋b）含量的峰值均出现在7月;叶片GO活性季节变化为单峰型曲线,8月最（252nmol／mg&#183;min）;RuBPCase活性季节变化为双峰曲线,6月和9月各有一峰值,分别为275nmol／mg&#183;min和248nmol／mg&#183;min,8月出现低谷;叶绿素含量和酶活性受光合有效辐射（PAR）与气温（Tair）的影响较大。     

Seasonal Variation in Pollen Catch in a Black Spruce Orchard

Pollen monitoring was conducted over three years (1987–1989) in a 12.4 ha Picea mariana (Mill.) B.S.P. (black spruce) seedling seed orchard established from 1979 to 1984. Pollen traps were installed around and within the orchard and collected daily. Pollen-cone production was highest in 1988 with an average of 0, 11, 20, and 38 cones per tree for 5-, 8-, 9-, and 10-year-old trees. Trees of the oldest section of the orchard bore about 60% of the total number of orchard pollen cones in 1987 and 1988 but only 26% in 1989. Pollen contamination during seed-cone receptivity was important in all three years assessed. The increase in pollen contamination from 1988 to 1989 resulted, in part, from 1) the roguing of 63% of trees in the oldest section of the orchard and 2) a 17-fold decrease in orchard pollen production from 1988 to 1989 compared to a 5-fold decrease from contamination sources.     

Seasonal and Spatial Variation in Nematode Communities in a Negev Desert Ecosystem

Seasonal and spatial variation in soil nematode communities was investigated in a field study conducted on a loessial plain in the northern Negev Desert, Israel. Soil samples from 0- to 50-cm depths were collected seasonally during 2001 under the canopy of Atriplex halimus and Hammada scoparia, and between shrubs (control). Total population abundance ranged from 8 to 887 individuals per 100 g soil, represented by 32 genera from 16 families. Significant temporal and vegetation effects were elucidated using most ecological indices applicable to express nematode community composition. Of those indices computed, only the Shannon index, the modified maturity index, and genus dominance distinguished differences in vertical distribution.     

Seasonal Variation of Ichthyoplankton in a Western Caribbean Bay System

The plankton of Bahia de la Ascension was sampled monthly, from August 1990 to July 1991, to ascertain ichthyoplankton composition, abundance, and seasonality. These data were used to assess the inferred function of the bay as spawning and nursery grounds. Fifty-one families, 66 genera, and 53 species of fish embryos and larvae were identified. Engraulidae, Clupeidae, Labrisomidae, Callionymidae, Gerreidae, and Gobiidae comprised 81.5% of the larvae captured: the remaining 18.5% included several coral reef fish families. Greatest mean fish egg densities were recorded between December and April, 341–246 per 100m³, suggesting a major spawning period. The monthly mean density of total fish embryos and larvae showed two peaks: one in late dry season (June), dominated by newly hatched engraulid, and a second (December) during the cold-front season with high densities of preflexion labrisomid and engraulid embryos. When labrisomid and engraulid embryos and larvae were excluded, densities peaked in the rainy season (July to October). Gerreidae and Callionymidae were significantly more abundant in the rainy season, while Labrisomidae and Gobiidae in the cold-front season. The highest embryos and larvae richness was observed in August during the rainy season with mean value significatively greater than those from cold-front and dry seasons. The occurrence of high egg densities and the wide range of embryos and larva stages are evidences that Bahia de la Ascension is a regionally important spawning and nursery ground for marine fish. Because this study covered partially the marine ecosystem of Bahia de la Ascension using convential gear, we suggest to conduct further research for have a full understanding of the importance of this bay for fish recruitment.