Which factors explain the decline in infant and child mortality in Matlab,Bangladesh?

Infant and child mortality rates have decreased substantially in Matlab, Bangladesh, as they have in many developing areas. We use data from the Matlab Demographic Surveillance System on nearly 94,000 singleton live births that occurred between 1987 and 2002 to investigate the extent to which the change in mortality over this period can be explained by changes in reproductive patterns and socio-economic characteristics. We estimate Cox proportional hazards models for four subperiods of infancy and childhood. Changes over time in reproductive patterns (maternal age, parity, and pregnancy spacing) and in the socio-economic characteristics we consider (e.g. maternal education, SES) explain between 10 and 40% of the decline in mortality rates. Changes in maternal education explain the largest portion of the reduction in infant and child mortality over time that we are able to explain, followed by reductions in the incidence of short interpregnancy intervals. In the other direction, decreases in fertility over time led to increases in the proportion of births that were first births, putting upward pressure on mortality.

Understanding the effects of siblings on child mortality: evidence from India

Given the intrinsically sequential nature of childbirth, timing of a child’s birth has consequences not only for itself but also for its older and younger siblings. The paper argues that prior spacing and posterior spacing between consecutive siblings are thus important measures of intensity of sibling competition for limited parental resources. While the available estimates of child mortality tend to ignore the endogeneity of sibling composition, we use a correlated recursive model of prior and posterior spacing and child mortality to correct it. There is evidence that uncorrected estimates under-estimate the effects of prior and posterior spacing on child mortality.

Upper and lower bounds on the variances of linear combinations of the kth records

We describe a method of determining upper bounds on the variances of linear combinations of the kth records values from i.i.d. sequences, expressed in terms of variances of parent distributions. We also present conditions for which the bounds are sharp, and those for which the respective lower ones are equal to zero. A special attention is paid to the case of the kth record spacings, i.e. the differences of consecutive kth record values.     

Likelihood ratio comparisons among spacings related to both one or two samples

In this paper, we investigate some stochastic comparisons in terms of likelihood ratio ordering between spacings from independent random variables exponentially distributed with different scale parameters. We partially solve some open problems in [Wen S, Lu Q, Hu T. Likelihood ratio orderings of spacings of heterogeneous exponential random variables. J Multivariate Anal. 2007;98:743–756] for a one-sample problem and in [Hu T, Lu Q, Wen S. Stochastic comparisons and dependence of spacings from two samples of exponential random variables. Commun Stat – Theory Methods 2006;35:979–988] for a two-sample problem. Specifically, we prove that the second spacing is always smaller than the third spacing in terms of the likelihood ratio order and we provide the ordering among all spacings in the case n=4. In the two-sample case, we establish comparisons between the second spacings related to each sample under certain conditions.     

二维和三维氢原子能级精细结构比较

从二维和三维氢原子能级的精细结构表达式出发,进行数值计算,找到能级的精细结构数值的规律性。利用多媒体著作工具Multimedia TooBook计算能级并画出能级图和能级间距图,进行比较。证实从三维降为二维能级降低而能级间距增大。从基态到第一激发态、从第一激发态到第二激发态、从第二激发态到第三激发态二维能级间距分别是三维能级间距的4.74、2.05和1.61倍。     

元认知策略的本土化研究

本文从认知主体——学习者角度,通过显性和隐性记忆力的工作原理,提出了频率效应是隐性记忆力发生作用的主要因素,而有意注意则是显性记忆力发生作用的主要机制的这一观点。本文因此提出了如有意注意策略、关键词策略、重复策略和间隔策略等一系列外语词汇学习的元认知策略。并指出,以往的"过度扩展式"讲解单词的方法"弊大于利"。英语教师可以在教学中采取造句和搭配的方法,将学生的注意力从识别向产出过渡,从而缩小理解技能和产出技能之间的差距。     

Large-sample quantile estimation in pareto laws

A large-sample method of estimation for the parameters of Pareto laws is investigatedo The estimates are derived by using a small subset of k sample quantiles out of the original observations. The optimum spacing of the k quantiles is also examined. A Monte Carlo study compares this method with the method of moments and that of maximum likelihood for a selected set of parameter values and sample sizes.     

On Tests of Uniformity for Randomly Distributed Arcs on a Circle

Let n points be independently distributed on a circle. Moving in a counter-clockwise direction, place arcs of length a on the circle with the i^th are starting at the i^th point. We describe three simple tests of the hypothesis of uniformity based on vacancy, on number of spacings and on the length of the maximal spacing. The tests do not require knowledge of the random points. The asymptotic power of these tests is investigated, and it is shown that vacancy-based tests perform best of the three.     

Spacing Between Births in Odisha,India

Birth spacing is of considerable importance to study the tempo and quantum of fertility. Using data from the National Family Health Survey III, this study explored the birth interval dynamics in Odisha, an eastern state of India. The life table analysis of spacing between births clearly suggests that birth spacing in the recent past has increased and the proportion of women moving to the second, third, and fourth parity has declined, leading to the decline in fertility in Odisha. From the proportional hazards model, educational level of women, age of women at previous birth, sex and survival status of the previous child, and the period effect are found to be important determinants of birth spacing at higher parities. Socioeconomic differences do not show a large effect at lower order births. This highlights the fact that most women in Odisha, regardless of their background characteristics, tend to have second births.     

Gender differences in knowledge and attitudes toward modern and traditional methods of child spacing in Malawi

This paper examines male-female differences in knowledge and attitudes towards traditional and modern methods of child spacing in Malawi, based on the survey on traditional methods of child spacing in Malawi which was conducted in 1988. The results show that most people in Malawi are knowledgeable about both traditional and modern methods of child spacing. In general more men than women report knowledge and practice of traditional methods. For modern methods, however, females are more knowledgeable than males of all the specific methods, with the exception of condoms. The greater knowledge by women of female-based modern contraceptives appears to be a manifestation of the exclusion of males from the family planning program. The high rates of knowledge do not translate into equivalent high rates of utilization for both modern and traditional methods of contraception. The study further demonstrates that, while women are involved in making decisions to use contraception, the proportion of men initiating such decisions is greater than that of women. This finding calls for family planning planners to think seriously about revising their target population to include men.