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2.
In recent years much effort has been devoted to extending regression methodology to non-Gaussian data, where responses are not independent. These methods for dependent responses are suitable for data from longitudinal studies or nested designs. However, use of these methods for crossed designs seems to have serious limitations due to the intensive computations involved because of the intractable nature of the joint distribution. In this paper, we cast the problem in a Bayesian framework and use a Monte Carlo method, the Gibbs sampler, to avoid current computational limitations. The flexibility of this approach is illustrated by analyzing the interesting salamander mating data reported by McCullagh and Nelder (1989, Generalized Linear Models, 2nd edition, London: Chapman and Hall). 相似文献
3.
- Aquatic macrophytes formed dense beds in fallow areas during the four and a half months of the flood season in all but one deepwater rice-growing location in Bangladesh; these included several types of life-form, but the fine-leaved species, Myriophyllum sp., Najas indica, Utricularia stellaris were often especially abundant. The same species grew inside deepwater rice fields, but at much lower densities. A similar contrast occurred for the algae, although deepwater rice often developed dense masses of epiphytes on aquatic roots, stems and leaf sheaths, when plants were growing in isolated, well-illuminated situations.
- Two widespread algae, Aulosira fertilissima and Scytonema mirabile, were equally successful on soil in the period prior to the arrival of floodwaters and floating on the surface of the water during the flood season. Other species common during the flood season differed from those common on soil.
- Most blue-green algae inside deepwater rice fields were heterocystous; the only species not so, but forming distinct colonies, was Aphanothece stagnina. However only non-heterocystous forms were found at one location in south Bangladesh (Phaltita) and a change from heterocystous to non-heterocystous forms was noted at the main research site (near Sonargaon) during late September in at least one year. The water column at the former was almost entirely anoxic, while the change at the latter occurred at a time when the water sometimes became anoxic during the night. It is suggested that differences in ability to tolerate anoxic periods may be a key factor in determining the success of the algal and vascular plant species in the different micro-habitats within these DWR-growing areas.
- Although diatoms were quantitatively only a minor component of the algal biomass, they became more frequent later in the season when the water became microaerobic or anoxic for part of the day. Navicula confervacea was overall the most abundant species at the two main research locations.
4.
In a prospective study of 2324 women in Matlab, Bangladesh, the occurrence of primary and 2ndary sterility by age groups was examined. The results were related to the nutritional status of the women, as assessed by measurements of height, weight, arm circumference and ponderal index. Approximately 98% of the women who were in the age group 15-19 were found to be fertile. This proportion decreases gradually up to the age group 30-34 years and thereafter declines sharply, reaching only 31% in the age group 45-49. The height data suggest no significant difference in the age pattern of sterility among the 3 groups of women, although there is a slight tendency that women who were less tall reached menopause earlier than the other 2 groups. Variations in weight are more conspicuous than in height. There is the suggestion that thinner women may experience an earlier menopause. Women having an arm circumference less than 21 cm, between 21-22 cm, and 23 cm and above, and currently aged 17 years, have an expected fertile life estimated at 25.0, 25.8, and 26.6 years respectively. The median ages at sterility were 42.8, 44.0, and 44.3 years respectively with a difference of about 1 year between the 1st 2 groups. This suggests that sterility occurs earlier among the thinner women. Since detailed investigation of nutritional status was not possible, it was assessed by anthropometry. There was strong evidence that nutritional status is an important factor in the estimated age at sterility, with thinner women experiencing an earlier menopause. Although it is impossible to measure the onset of sterility, one can obtain a minimum estimate of it from the age-specific distribution of the proportion of women who have not produced a child for 5 years of being at risk. 相似文献
5.
Phytoplankton production and respiration in the Blue Nile and White Nile at Khartoum were measured during the period November 1969–January 1971 using the light and dark bottle technique. Maximum rates of production coincided with periods of maximum phytoplankton densities. In the Blue Nile gross production varied between 0.00 gCm–3d–1 during the flood season and 2.19 gCm–3d–1 (0.49 mgO2l–1h–1) during November 1969. In the White Nile the range was from 0.41 gCm–3d–1 (0.09 MgO2l–1h–1) in May to 3.74 gCm–3d–1 (0.83 MgO2l–1h–1) in November. The maximum rates of respiration in the Blue Nile and White Nile were 0.10 and 0.63 MgO2l–1h–1 respectively. The ratios net:gross production were generally higher in the White Nile than in the Blue Nile. 相似文献
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The influences of household economic condition, maternal education, sex, and nutritional status of children on mortality were examined using multivariate analytical techniques. Weights of around 1700 children aged 2 60 months in five villages of Matlab, Bangladesh, were taken during the first half of 1981. The children were followed for 18 months and their survival was recorded. The severely malnourished children had a risk of death nine times that of their counterparts with better nutritional status. Female children had a higher risk of death than the males. Mother's education and economic condition of household also showed negative relationships with the risk of death, but the effect of mother's education was modified by economic condition and sex of the children. 相似文献
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9.
Use of lysophosphatidylethanolamine, a natural lipid, to retard tomato leaf and fruit senescence 总被引:3,自引:0,他引:3
We studied the influence of lysophosphatidylethanolamine (LPE) on the pattern and rate of ethylene production and respiration of tomato ( Lycopersicon esculentum cv. H7155) leaflets and fruit. Leaflets that had been senescing on the plant showed a climacteric-like rise in ethylene production but not in respiration rate which decreased continuously with leaf age. Detached leaflets had a climacteric-like pattern in respiration whether they were incubated in complete darkness or in light. Detached leaflets incubated in the dark had higher rates of ethylene production and CO2 evolution than did light-incubated leaves. There was no change in the pattern of ethylene production or CO2 evolution as a result of LPE treatment. However, LPE-treated attached and detached leaflets had consistently lower rates of CO2 evolution. The reduction in CO2 evolution by LPE was most pronounced at the climacteric-like peak of the detached leaves. LPE-treated leaflets had a higher chlorophyll content and fresh weight and lower electrolyte leakage than the control. LPE-treated fruits had lower rates of ethylene and CO2 production than did the control. LPE-treated fruits also had higher pericarp firmness and lower electrolyte leakage than the control. The results of the present study provide evidence that LPE is able to retard senescence of attached leaves and detached leaves and tomato fruits. Several recent studies suggest that lysolipids can act in a specific manner as metabolic regulators. Our results suggest a specific role of lysolipid LPE in aging and senescence 相似文献
10.
Juliette Gaëtan Sébastien Halary Maxime Millet Cécile Bernard Charlotte Duval Sahima Hamlaoui Amandine Hecquet Muriel Gugger Benjamin Marie Neha Mehta David Moreira Fériel Skouri-Panet Cynthia Travert Elodie Duprat Julie Leloup Karim Benzerara 《Environmental microbiology》2023,25(3):751-765
The formation of intracellular amorphous calcium carbonates (iACC) has been recently observed in a few cultured strains of Microcystis, a potentially toxic bloom-forming cyanobacterium found worldwide in freshwater ecosystems. If iACC-forming Microcystis are abundant within blooms, they may represent a significant amount of particulate Ca. Here, we investigate the significance of iACC biomineralization by Microcystis. First, the presence of iACC-forming Microcystis cells has been detected in several eutrophic lakes, indicating that this phenomenon occurs under environmental conditions. Second, some genotypic (presence/absence of ccyA, a marker gene of iACC biomineralization) and phenotypic (presence/absence of iACC) diversity have been detected within a collection of strains isolated from one single lake. This illustrates that this trait is frequent but also variable within Microcystis even at a single locality. Finally, one-third of publicly available genomes of Microcystis were shown to contain the ccyA gene, revealing a wide geographic and phylogenetic distribution within the genus. Overall, the present work shows that the formation of iACC by Microcystis is common under environmental conditions. While its biological function remains undetermined, this process should be further considered regarding the biology of Microcystis and implications on the Ca geochemical cycle in freshwater environments. 相似文献