Temporal variation of phytophilous Chironomidae over a 11-year period in a shallow Neotropical lake in southern Brazil

Small and shallow lakes make up most of the lake-covered area in the world, and immature Chironomidae generally constitute the dominant group among invertebrates in these systems, exhibiting a wide distribution and tolerance to various levels of water quality. The changes in trophic features associated with the dominance of different major primary producers (macrophyte and phytoplankton) are reflected in the functioning of these ecosystems and likely in their phytophilous Chironomidae species richness and abundance. These were thus studied in a Brazilian shallow lake over a 11-year period characterized by both clear and turbid water conditions in relation to water quality and dominant macrophytes. The results revealed differences in Chironomidae composition but not in richness associated with clear and turbid waters. The Goeldichironomus genera predominated during all years and for different macrophyte types (freefloating, floating leaf, and submerged). We attribute the variability of Chironomidae assemblages to changes in macrophyte dominance and water trophic status, such as the concentration of nutrients and chlorophyll-a, during the 11-year period. Submerged macrophytes were associated with clear waters and harbored the highest diversity, which emphasized the importance of these environmental conditions for preserving the biodiversity of Chironomidae in shallow lakes.     

Temporal, seasonal, and regional differences in births and deaths in Aland (Finland)

A good knowledge of the seasonal variation during normal years is of fundamental importance for analyses of the effects of wars, famines, epidemics, or similar privations on births and deaths. In this study we consider data from the Aland Islands (Finland) for 1650-1950. During the period 1650-1793 there are subperiods with missing data for all parishes, and consequently the total data for the Aland Islands for this period have to be estimated using available data. For the period 1794-1950 the registered data seem to be complete and reliable, but the war year 1809 shows a marked deficit of births. During the last decades of the 19th century the number of births increases markedly and after that shows a strong decrease. After the 1930s births increase again. To allow seasonality comparisons between the Aland Islands as a whole and its subregions, we base our studies on seasonal indexes. There is a markedly decreasing temporal trend in the seasonal variation of births for the Aland Islands as a whole, but the general pattern remains mainly the same, having two peaks, one in March-April and one in September-October. For the period 1901-1950 the seasonal variation almost disappeared. The strength of the seasonal variation in births shows regional differences, but the general pattern is mainly the same. The outermost parish, K?kar, an isolate of its own, shows the strongest seasonal variation in births. The annual number of deaths shows some marked peaks, especially in the war year 1809. For both sexes there are marked peaks in 1809, indicating that the deaths were mainly caused by epidemic diseases rather than by killing in battles. For mortality a decreasing trend in the seasonal variation is observed during 1650-1750, but after 1751-1800 the strength of seasonality shows an increasing trend and a sinusoidal pattern.     

Monitoring exercise stress by changes in metabolic and hormonal responses over a 24-h period.

Metabolic and endocrine responses of 14 subjects of varying levels of fitness to an intensive anaerobic interval training session were assessed before exercise and at 2 h, 4 h, 8 h and 24 h postexercise. The endocrine response of the same subjects to a control day, where they were required not to exercise, was also assessed and compared with the values obtained on the interval training day. Uric acid, urea, and creatine phosphokinase concentrations still remained elevated above pre-exercise values 24 h postexercise. Lactate, creatinine, testosterone and cortisol concentrations were significantly elevated above pre-exercise values immediately postexercise but these had reversed by 2 h postexercise. Over the remainder of the recovery period testosterone concentrations remained significantly lower than values measured at similar times on the control day. This was shown to be due directly to a change in testosterone as sex hormone binding globulin concentration remained constant throughout the recovery period. The data indicate that when comparisons of data were made to control (rest) days, imbalances in homeostasis, due to intensive training, are not totally reversed within the next 24-h. The data also demonstrate that the parameters measured undergo the same variations in subjects with a wide range of physical fitness, indicating that these parameters could be used to monitor exercise stress and recovery in athletes of a wide range of abilities.(ABSTRACT TRUNCATED AT 250 WORDS)     

Seasonal variation in response to stimulation and related embryo transfer procedures in Alberta over a nine year period

From 1974 to 1982 inclusively, 6000 attempts were made to stimulate superovulation in commercial donors. An average of 10.3 ovulations per stimulation was estimated over this period. There were large variations in the response (1) of individual animals, (2) between months in each year and (3) in yearly averages for successive years. This variation was due in part to the gonadotropins used, to the responsiveness of the animals to gonadotropin and to the inaccuracy of the estimates of ovulation numbers. Similarly, both the recovery of ova from stimulated donors and their suitability for transfer to recipients varied but not in a manner consistent with a seasonal effect. Pregnancy rates appeared to be lowest when embryos were transferred to recipients in December, January or February but this can be overcome by freezing embryos collected during this period for transfer at other times. A consistent effect of season on embryo transfer results was not observed in this study.     

Seasonal variation of livebirths, stillbirths, extramarital births and twin maternities in Switzerland.

A study was made of the seasonal variation in all births, and births according to marital status, multiplicity and birth status (live and still) in Switzerland recorded between 1876 and 1990. To obtain seasonal variation in as pure as possible form, our analyses are based on rates. When comparing the seasonality in data sets showing markedly different levels, standardised indices were used. Assuming the length of pregnancies with twins to be about one month shorter than for pregnancies with singletons, lagged twinning rates were calculated but, in comparison with actual twinning rates, the general seasonal variation remained. Therefore, this study was based on actual twinning rates. A monotonic increase in the amplitude of the seasonal variation in general births was noted for the period 1876-1930, with strong seasonal variation holding for 1921-1980. After that, a marked decline in the amplitude can be observed. Seasonality of both all births and twin maternities showed very similar pattern for the periods 1876-1930 and 1969-1990, with maxima in the spring (March-May) and troughs in late autumn (October-December). Twin maternities showed a strong seasonality for the period 1876-1930, being about 20% higher in March than in October. The twinning rate in the period 1876-1930 was about 2.6 per thousand units higher than in the period 1969-90. For twin maternities there was also a stronger seasonal variation during the earlier period than during the later one. The pattern of the seasonal variation for extramarital births, showing a maximum in February (conceptions in May-June) and a minimum in August (conceptions in November-December) with a difference of no less than 24% was more marked than for the marital births. It seems likely that this seasonality of extra-marital maternities was due mainly to seasonal variation of coital rates and multiple ovulation in the early summer months coinciding with optima of light, temperature and food supply. A strong reduction in the rate of stillbirths (gestational age more than 29 weeks) was observed during the twentieth century. The stillbirth rate declined from about 40 per 1000 in the 1870s to fewer than 5 per 1000 in the 1980s. Irrespective of this strong decline in the stillbirth rate, the same seasonal rhythm was noticed throughout the period with high stillbirth rates among births around March and low rates during the summer and autumn.     

Spina bifida and hydrocephalus: a population study over a 35-year period.

The records of the B.C. Health Surveillance Registry were used to analyze all live births with spina bifida and hydrocephalus (SBHC) in British Columbia between 1952 and 1986 inclusive. A total of 479 cases (218 males and 261 females) occurred during this period in 1,298,267 consecutive live births, for an incidence of 3.7/10,000. There were more females, with the sex ratio being significantly different from that of the general population born over this period. No significant seasonal differences were observed over the time period. A comparison of life expectancy for individuals born 1962-1970 and 1970-1986 showed significant improvement in the probability of surviving to the age of 1 year for the latter group. There was also a small but statistically significant increased chance of surviving to age 7 years in the latter group but no difference in the probability of surviving from 7 years to 16 years. Life expectancy figures are shown in a format practical for counseling with regard to prognosis for affected individuals. Additional malformations not attributable to SBHC were observed in 6% (27 cases). These included renal anomalies, cleft lip and/or palate, tracheoesophageal fistula, and diaphragmatic hernia. The incidence of each defect was significantly greater than in the general population of births.     

Seasonal variation of births in rural West Bengal: magnitude, direction and correlates

This paper examines seasonal variation of births in a rural community of West Bengal, India, by exploring data from the 1992-93 National Family Health Survey. Suitable time series analyses were used to determine the seasonal pattern of births and to estimate peaks. The trigonometric regression technique was used to carry out this objective. The study attempted to link the results of the regression analysis to the atmospheric temperature of the region during 1987-91, the distribution of respondents' husbands' occupations and the marriage pattern of the community. It was found that, in the study population, conceptions were numerous in the first quarter of a calendar year and the distribution of conceptions over calendar months was negatively associated with the average monthly temperature. In addition, the marriage pattern of the community and the occupational distribution of the fathers also had a significant effect on the distribution of births over calendar months. It is hoped that the findings will boost the development of needs-based maternal and child health (MCH) and family planning programmes in the community.     

Temporal differences in the regional twinning rates in Sweden after 1750.

When twinning rates are studied, maternal age and parity should be considered. Data on parity are seldom available. We studied information about the mean parity, using the gross reproduction rate, the total fertility rate and the crude birth rate. These are strongly correlated with the mean parity. The crude birth rate is more readily available than the gross reproduction rate or the total fertility rate. Earlier studies have shown that it is difficult to model variations in the twinning rate with data for the macrolevel. In this study these findings are explained by theoretical analyses and illustrated by empirical data. Sweden, having the oldest continuous population statistics and high twinning rates, offers excellent possibilities for analyses of the twinning rate. We considered data for the counties of Gotland, Alvsborg and Stockholm and the city of Stockholm from 1749 to 1960 and for Sweden until 1996. For Alvsborg, the twinning rate was low for the whole period, showing no statistically significant decreasing trend. It is mainly about 11-14 per thousand, which is only 50-60% of the twinning rate in Gotland in the 18th century. In Gotland, in the county of Stockholm, in the city of Stockholm and in Sweden as a whole, the decreasing trends in the twinning rate were statistically significant. The decreasing twinning rates converge towards the low twinning rate of Alvsborg. After standardization of the twinning rate, the differences remained and the low rate in Alvsborg could not be explained by maternal age.     

Climate changes affecting biotic interactions,phenology, and reproductive success in a savanna community over a 10-year period

Climatic parameters are able to influence the timing of phenological events affecting the degree of synchrony among plant species, their interactions, and reproductive success. Shrubs of Malpighiaceae family in the Brazilian Tropical Savanna present sequential flowering phenology. We verified variations in climatic factors (temperature and precipitation) over a period of 10 years (2005–2014) and correlated them with the onset of flowering of four of these Malpighiaceae species. Furthermore, we tested whether the phenological synchronization among species has changed over time affecting the herbivory and fruit set. Herbivory and fruit production were recorded during three reproductive seasons (2008/2009, 2011/2012, 2013/2014). We developed a mathematical model to estimate the flower and fruit production in response to phenological changes for the next 5 years. Results show that climatic factors changed, influencing the onset of species flowering. The degree of overlap among species also changed and the effects on species interactions were species specific. The mathematical model successfully presented a tendency on flower and fruit production contributing to the predictions of the outcomes in response to phenological changes. We confirm the effects of climate changes on plant phenological events and the importance of feature plasticity for better performance of species.     

Comparative evolution of GII.3 and GII.4 norovirus over a 31-year period

Noroviruses are the most common cause of epidemic gastroenteritis. Genotype II.3 is one of the most frequently detected noroviruses associated with sporadic infections. We studied the evolution of the major capsid gene from seven archival GII.3 noroviruses collected during a cross-sectional study at the Children's Hospital in Washington, DC, from 1975 through 1991, together with capsid sequence from 56 strains available in GenBank. Evolutionary analysis concluded that GII.3 viruses evolved at a rate of 4.16 × 10(-3) nucleotide substitutions/site/year (strict clock), which is similar to that described for the more prevalent GII.4 noroviruses. The analysis of the amino acid changes over the 31-year period found that GII.3 viruses evolve at a relatively steady state, maintaining 4% distance, and have a tendency to revert back to previously used residues while preserving the same carbohydrate binding profile. In contrast, GII.4 viruses demonstrate increasing rates of distance over time because of the continued integration of new amino acids and changing HBGA binding patterns. In GII.3 strains, seven sites acting under positive selection were predicted to be surface-exposed residues in the P2 domain, in contrast to GII.4 positively selected sites located primarily in the shell domain. Our study suggests that GII.3 noroviruses caused disease as early as 1975 and that they evolve via a specific pattern, responding to selective pressures induced by the host rather than presenting a nucleotide evolution rate lower than that of GII.4 noroviruses, as previously proposed. Understanding the evolutionary dynamics of prevalent noroviruses is relevant to the development of effective prevention and control strategies.     

Decreased pulmonary diffusing capacity of divers over a 6-year period

Non-smoking, male, professional firemen divers (n = 15) underwent two pulmonary function tests (PFT) separated by 6 years. Measured data were compared to European Coal Steel Community recommended reference values to permit cross-sectional and then longitudinal study. Higher vital capacity (VC; P < 0.01) and forced expiratory volume in 1 s (FEV₁; P < 0.05), and lower maximal mid-expiratory flow (MMEF) coefficient with VC (MMEF/VC; P < 0.05) were observed in both PFT. Diver's pulmonary diffusing capacity (DL_CO) and the coefficient with alveolar volume (DL_CO/V _A) showed significantly (P < 0.001) different evolution profiles than those expected from predicted values. In divers, DL_CO and DL_CO/V _A decreased from 104.0% to 91.4% and from 106.4% to 91.5% of predicted values respectively. Changes in DL_CO and DL_CO/V _A correlated positively with the initial measurement of DL_CO (r = 0.67, P < 0.01) and DL_CO/V _A (r = 0.74, P < 0.01) respectively, whereas no correlation between changes in pulmonary gas transfer function and age or diving history parameters was found. Thus, it is suggested from our observations that hyperbaric atmosphere exposure increases the effects of aging on pulmonary diffusing capacity and that pulmonary gas transfer function should be regularly tested in professional and recreational divers. Accepted: 22 February 1997     

Seasonal changes in the copper content of the liver of the Common shrew, Sorex araneus over a two-year period

Seasonal changes in the liver copper content of the common shrew were measured over two years. The copper content increased rapidly in autumn; in one year the levels remained high until the Spring, but the following winter there was a sharp decrease after December. It is suggested that differences in liver copper content are connected with differences in the metabolic steady state caused by differing environmental conditions in the two winters.     

Increase in the incidence of peritoneal collagen balls over a 10-year period

OBJECTIVE: To describe the detection of collagen balls in peritoneal washings over a 10-year period, revealing an unexpected and unexplained higher incidence than in the past. STUDY DESIGN: Reports of routinely processed, Papanicolaou-stained smears and cytospins and hematoxylineosin-stained cell blocks from peritoneal washes and ascitic fluids seen over an 8-year period (1995-2002) were reviewed, and the percentage of specimens in which collagen balls were noted was determined. To rule out a learning curve phenomenon, the first 100 consecutive peritoneal washings and ascitic specimens from years 1993-2001 plus 2002 were rescreened, and the percentage of specimens containing collagen balls was determined. RESULTS: The percentages of cases with collagen balls increased steadily beginning with 8 of 467 cases (3.2%) in 1995 to 185 of 650 (28.5%) in 2002, as reported in the case records. Rescreened cases also showed a similar increase, 4.0% in 1993 to 29% in 2002. No procedural modifications were made in specimen processing during this interval, nor are we aware of any procedural change in obtaining cytologic samples. CONCLUSION: An unexplained 7-fold increase in the percentage of peritoneal samples with collagen balls occurred over a 10-year period. This increase cannot be attributed to changes in specimen handling or to a learning curve phenomenon. This finding is of unknown significance and may warrant further investigation.     

Changes in strength over a 2-year period in professional rugby union players

The purpose of this study was to assess the magnitude of upper and lower body strength changes in highly trained professional rugby union players after 2 years of training. An additional purpose was to examine if the changes in strength were influenced by the starting strength level, lean mass index (LMI), or chronological age. This longitudinal investigation tracked maximal strength and body composition over 3 consecutive years in 20 professional rugby union athletes. Maximal strength in the bench press and back squat and body composition was assessed during preseason resistance training sessions each year. The athletes completed a very rigorous training program throughout the duration of this study consisting of numerous resistance, conditioning and skills training sessions every week. The primary findings of this study were as follows: (a) Maximal upper and lower body strength was increased by 6.5-11.5% after 2 years of training (p = 0.000-0.002 for bench press; p = 0.277-0.165 for squat); (b) magnitude of the improvement was negatively associated with initial strength level (r = -0.569 to -0.712, p ≤ 0.05); (c) magnitude of improvement in lower body maximal strength was positively related to the change in LMI (an indicator of hypertrophy; r = 0.692-0.880, p ≤ 0.05); and (d) magnitude of improvement was not associated with the age of professional rugby union athletes (r = -0.068 to -0.345). It appears particularly important for training programs to be designed for continued muscle hypertrophy in highly trained athletes. Even in professional rugby union athletes, this must be achieved in the face of high volumes of aerobic and skills training if strength is to be increased.     

The chemical composition of Astragalus. variations within the plants over a 6-year period

COWGILL, U. M. & LANDENBERG, B. D., 1991. The chemical composition of Astragalus : variations within the plants over a 6-year period. No systematic chemical examination has been carried out on seleniferous plants coexisting with non-seleniferous ones. This paper is confined to elemental variation within the plants (12 species of seleniferous Astragalus, 15 species of non-seleniferous Astragalus and seven species of other plants) gathered from 23 sites over a 6-year period in Colorado, Utah and New Mexico, U.S.A. Analytical procedures include X-ray fluorescence and atomic absorption spectrometry. Only 19 elements, of 49 detected, showed significant differences in their quantities in different plant parts. Mn S, Ca, Sr and Mg concentrated in leaves; Al, Si, Ti, Cu, As, F, CI and Br accumulated in stems and K, Rb, Cs, Zn, P and Se were found in quantity in the reproductive parts. A comparison of seleniferous with non-seleniferous species revealed that Mg, S, Mn (leaves), Se, P, K, Zn (flowers/seeds) Cu, F and CI (stems) were more concentrated in seleniferous species ( P < 0.0001) whereas Ca (leaves), Rb (flowers/seeds), As, Al, Si and Br (stems) were present in greater amounts in non-seleniferous ones ( P < 0.0001). An hypothesis is proposed to explain the high amounts of Mg encountered in leaves of these arid region plants; according to the hypothesis some portion of the accumulated Mg functions in arid plants as a humidity stabilizer. Another hypothesis concerns the relationship observed between Se and As. It has been shown that non-seleniferous astragali contained significantly more As than coexisting seleniferous astragali. It is proposed that As may function to time seed production in such a way that non-accumulators have passed the full bloom stage by the time coexisting accumulators were in full bloom and volatilizing quantities of seleniferous compounds.