Bayesian Estimation of the Distribution Function of the Poisson Model

This paper presents the Bayes estimators of the Poisson distribution function based on complete and truncated data under a natural conjugate prior. Laplace transform of the incomplete gamma function and the Gauss hypergeometric function have been employed in order to overcome the intractability of the integrals. Numerical examples from biosciences are given to illustrate the results. A Monte Carlo study has been carried out to compare Bayes estimators under complete data with the corresponding maximum liklihood estimators.     

The demography of the coelacanth Latimeria chalumnae

Synopsis The very sparse data that are available on the abundance, population structure and biology of the coelacanth Latimeria chalumnae off Grand Comoro are summarised, and some simple numerical analyses are carried out to explore certain aspects of the population dynamics, particularly the age-profile of the population. The object has not been to provide estimates of key demographic parameters, such as mortality rates, but to propose various scenarios that are useful for comparison with real data as they become available. The analysis also makes it possible to reach some preliminary conclusions that are relevant to the management of the coelacanth population. For instance, it appears that the catch rate of coelacanths by artisanal fishermen may have a negligible effect on coelacanth survivorship, and it is more likely that population size and structure are determined by natural mortality rates and birth rates. It is suggested that predation is the main cause of natural mortality and that the main predators of coelacanths are likely to be large sharks. Interference with the traditional patterns of the Comoran artisanal fishery may threaten the coelacanth. Several important gaps in our knowledge of coelacanth demography are identified.     

Models of seasonal growth of the equatorial carp Labeo dussumieri in response to the river flood cycle

Synopsis The phenology of Labeo dussumieri, an omnivorous carp common to South Asia, was investigated in a population inhabiting a flood plain anabranch of the Mahaweli Ganga, Sri Lanka. The Mahaweli Ganga exhibited a bimodal discharge pattern typical of many equatorial rivers, with a minor peak during the S.W. monsoon and a major peak during the N.E. monsoon. Seasonal changes in several lotic variables were measured in an attempt to correlate changes in environmental conditions to reproduction and growth in L. dussumieri. The onset of gonad recrudescence and spawning were synchronized with the increased river discharge during the S.W. and N.E. monsoons: gonad development followed one monsoonal discharge peak and spawning took place at the beginning of the other. Most fish spawned at the beginning of the major discharge peak in October and November, following the September dry season. Increased discharge was concomitant with a fall in temperature, light intensity, pH and conductivity. Growth was shown to be seasonal, exhibiting an annual bimodal pattern with peaks coincident with S.W. and N.E. monsoonal rains. Seasonal changes in growth were expressed by two models in terms of: (a) change of somatic weight or fork length with time, (b) change of specific growth rate in response to river discharge, modified by somatic weight. Gonad recrudescence and spawning stress did not appear to influence growth rate.     

Growth ofDiacrisia obliqua [Lep.: Arctiidae] with low doses ofBacillus thuringiensis var.Kurstaki

Early 3rd instarDiacrisia obliqua Walk. larvae were treated with concentrations ofBacillus thuringiensis var.kurstaki (Dipel^®) and the growth of treated larvae was assessed. All the doses reduced significantly the weight and survival of the insects (p<0.001).     

Effects of 12 weeks of aerobic exercise plus dietary restriction on body composition, resting energy expenditure and aerobic fitness in mildly obese middle-aged women

This study investigated the effects of 12 weeks of aerobic exercise plus voluntary food restriction on the body composition, resting metabolic rate (RMR) and aerobic fitness of mildly obese middle-aged women. The subjects were randomly assigned to exercise/diet (n = 17) or control (n = 15) groups. The exercise/diet group participated in an aerobic training programme, 45–60 min · day ^–1 at 50%–60% of maximal oxygen uptake (VO_2max), 3–4 days · week^–1, and also adopted a self-regulated energy deficit relative to predicted energy requirements (–1.05 MJ · day ^–1 to –1.14 MJ · day ^–1 ). After the regimen had been followed for 12 weeks, the body mass of the subjects had decreased by an average of 4.5 kg, due mainly to fat loss, with little change of fat free mass (m _ff). The absolute RMR did not change, but the experimental group showed significant increases in the RMR per unit of body mass (10%) and the RMR per unit of m _ff (4%). The increase in RMR/m _ff was not correlated with any increase in VO_2max/m _ff. The resting heat production per unit of essential body mass increased by an average of 21%, but the resting heat production rate per unit of fat tissue mass remained unchanged. We concluded that aerobic exercise enhances the effect of moderate dietary restriction by augmenting the metabolic activity of lean tissue.     

Contrasting rates of nucleotide substitution in the X-Linked and Y-Linked zinc finger genes

We have sequenced the entire exon (1,180 bp) encoding the zinc finger domain of the X-linked and Y-linked zinc finger genes (ZFX and ZFY, respectively) in the orangutan, the baboon, the squirrel monkey, and the rat; a total of 9,442 by were sequenced. The ratio of the rates of synonymous substitution in the ZFY and ZFX genes is estimated to be 2.1 in primates. This is close to the ratio of 2.3 estimated from primate ZFY and ZFX intron sequences and supports the view that the male-to-female ratio of mutation rate in humans is considerably higher than 1 but not extremely large. The ratio of synonymous substitution rates in ZFY and ZFX is estimated to be 1.3 in the rat lineage but 4.2 in the mouse lineage. The former is close to the estimate (1.4) from introns. The much higher ratio in the mouse lineage (not statistically significant) might have arisen from relaxation of selective constraints. The synonymous divergence between mouse and rat ZFX is considerably lower than that between mouse and rat autosomal genes, agreeing with previous observations and providing some evidence for stronger selective constraints on synonymous changes in X-linked genes than in autosomal genes. At the protein level ZFX has been highly conserved in all placental mammals studied while ZFY has been well conserved in primates and foxes but has evolved rapidly in mice and rats, possibly due to relaxation of functional constraints as a result of the development of X-inactivation of ZFX in rodents. The long persistence of the ZFY-ZFX gene pair in mammals provides some insight into the process of degeneration of Y-linked genes.Correspondence to: W.-H. Li     

呼和浩特地区蔬菜污染现状综合评价

呼和浩特地区蔬菜污染现状综合评价杨在中（内蒙古大学,呼和浩特０１００２１）黄雅琴（内蒙古环境监测中心站,呼和浩特０１００１０）ＣｏｍｐｒｅｈｅｎｓｉｖｅａｓｓｅｓｓｍｅｎｔｏｎｐｏｌｌｕｔｉｏｎｓｔａｔｕｓｏｆｖｅｇｅｔａｂｌｅｓｉｎＨｕｈｅｈｏｔ．...     

布氏田鼠肥满度分析和小型兽类肥满度指标K与KWL（重长指标）的比较

通过对两个肥满度指标的理论和生物学意义分析,以及对布氏田鼠肥满度的研究和实际应用的讨论,认为描述动物的肥满度时,重长指标ＫＷＬ优于指标Ｋ。两指标的最大差别是成体的ＫＷＬ值大于幼体,而成体的Ｋ值小于幼体。布氏田鼠肥满度没有性别差异;有异著的年龄差异,成体鼠的肥满度高于幼鼠;有显著的季节变化,鼠种群春季肥满度最高,夏季降低,秋季回升;有显著的年际变化,高数量年的肥满度高于低数量年。     

The relative importance of prenatal and postnatal maternal influences on growth in mice

Summary The cross-nursing technique was used to assess the relative importance of prenatal and postnatal maternal influences on growth in mice from an unselected population originated from a cross of four highly inbred strains. Body weights were studied at birth, 7-, 14-, 21- and 42-days, in addition to the weight gains between these ages and tail length at 21 and 42 days of age. At littering, each dam in each nursing set retained two of her own offspring and two were transfereed to each of the other dams in the set, so that each nursed litter contained six young representing three mothers. Prenatal influences accounted for 37, 15, 10, 11 and 13 % of the total variation in the respective body weights, while postnatal influences accounted for 0, 64, 65, 49 and 14% at the respective ages. In the case of weight gains, prenatal influences were responsible for 16, 4, 6 and 30%, while postnatal influences were responsible for 66, 66, 31 and 7% of the total variation in gain during the respective four periods examined. Apparently the individual weight gain from 7 to 14 days was a better measure of the lactational performance of the dam than individual 14-day weight. For tail length, prenatal influences accounted for 6 % and 4 % of the total variation in tail length at 21 and 42 days, respectively, while postnatal influences accounted for 60 % and 24 % at the respective ages. Generally, there was no indication of an important interaction between the nurse and the nursed young at any stage studied.