Relevance of Risk Predictions Derived from a Chronic Species Sensitivity Distribution with Cadmium to Aquatic Populations and Ecosystems

Criteria to protect aquatic life are intended to protect diverse ecosystems, but in practice are usually developed from compilations of single‐species toxicity tests using standard test organisms that were tested in laboratory environments. Species sensitivity distributions (SSDs) developed from these compilations are extrapolated to set aquatic ecosystem criteria. The protectiveness of the approach was critically reviewed with a chronic SSD for cadmium comprising 27 species within 21 genera. Within the data set, one genus had lower cadmium effects concentrations than the SSD fifth percentile‐based criterion, so in theory this genus, the amphipod Hyalella, could be lost or at least allowed some level of harm by this criteria approach. However, population matrix modeling projected only slightly increased extinction risks for a temperate Hyalella population under scenarios similar to the SSD fifth percentile criterion. The criterion value was further compared to cadmium effects concentrations in ecosystem experiments and field studies. Generally, few adverse effects were inferred from ecosystem experiments at concentrations less than the SSD fifth percentile criterion. Exceptions were behavioral impairments in simplified food web studies. No adverse effects were apparent in field studies under conditions that seldom exceeded the criterion. At concentrations greater than the SSD fifth percentile, the magnitudes of adverse effects in the field studies were roughly proportional to the laboratory‐based fraction of species with adverse effects in the SSD. Overall, the modeling and field validation comparisons of the chronic criterion values generally supported the relevance and protectiveness of the SSD fifth percentile approach with cadmium.     

人口发展功能分区与主体功能分区的比较研究

以人口发展功能分区和主体功能分区的内涵特征为逻辑研究起点,采用规范研究与归纳总结相结合的研究方法,从功能区划的角度对两者的总体关系进行了比较分析。对比结果显示,两种区划都是我国体现人与自然关系的一种空间管制手段,但在功能、性质、作用和管理等方面存在的差异。在此基础上,通过找出两种功能区划统筹协调中存在的问题,简要地提出了协调两者的几点建议。     

论中国人口逆淘汰：驳斥一个伪命题

本文对中国人口（素质）逆淘汰问题进行定性和定量的分析，认为不能简单的以城乡生育率的差异去考量人口的整体素质变化。人口的整体素质变动是一个动态的过程，以静态的、封闭的人口观点去看待人口素质问题必然得出与事实不相符合的结论。把城镇、农村人口当作两个封闭的群体。同时忽视农村人口素质快速提升的的现实，得出的中国人口逆淘汰的结论必然是一个伪命题。     

中国人口变动与经济增长

人口具有生产和消费的双重属性,因此人口变动与经济增长密切相关。考察中国改革开放以来的经济增长态势,以人口为中心系统地分析影响中国改革开放以来经济持续高速增长的主要因素。中国的人口变动主要从四个方面促进了改革开放以来经济持续的高速增长;如果没有其他突发性因素的冲击,单从人口变动因素来看,中国经济还可能再持续增长二十年。     

Sequential confidence intervals for the number of cells in a multinomial population

A two-sided sequential confidence interval is suggested for the number of equally probable cells in a given multinomial population with prescribed width and confidence coefficient. We establish large-sample properties of the fixed-width confidence interval procedure using a normal approximation, and some comparisons are made. In addition, a simulation study is carried out in order to investigate the finite sample behaviour of the suggested sequential interval estimation procedure.     

Mortality following conjugal bereavement,Belgium 1991-96: The unexpected effect of education

This paper examines excess mortality following spousal bereavement by time since bereavement, sex, age, and education. The main hypothesis challenged is that higher education buffers the harmful effects of spousal loss. Using a log-rate model, death-rate ratios (widowed/married) are estimated for 49,849 and 126,746 Belgian widowers and widows and an equal number of non-bereaved controls matched to the bereaved on their socio-demographic characteristics. The hypothesis that the more educated suffer less excess mortality is not supported. Although higher educational levels are associated with lower mortality in general, they do not alleviate the effects of bereavement. On the contrary, in the period immediately following spousal loss, the more highly educated seem to have more, rather than less, excess mortality. Three possible arguments are suggested to account for this: education-related differences in the partner-relationship, structural differences in the availability of appropriate social support, and cultural differences in potential support networks.     

Effects of population policy and economic reform on the trend in fertility in Guangdong province,China, 1975–2005

An analysis of data mainly from China's 1990 and 2000 censuses and 2005 mini-census shows how fertility decline between 1975 and 2005 in the province of Guangdong has been influenced by both fertility policy and economic and social development. Guangdong's development since 1975 has been very rapid and has attracted huge numbers of migrants from other provinces. The analysis of the province's fertility trend from 1975 shows clearly the influence of fertility policy on the trend. The analysis also shows that economic development has brought about large changes in population composition by urban/rural residence, education, occupation, and migration status, which, together with large fertility differentials by these characteristics, have contributed substantially to Guangdong's fertility decline, in large part through changes in proportions currently married.     

RESEARCH NOTE Some evidence against the assumption that approval of family planning is associated with frequency of spouses' discussion of the subject

Much previous work on the relationship between respondent's reported frequency of discussion with spouse about family planning and correctness of reporting spouse's approval of family planning has led to the conclusion that discussion promotes approval. In this paper, data from the 1998 Kenya Demographic and Health Surveys are used to show that a focus on the relationship between frequency of discussion and correctness of reporting partner's disapproval of family planning leads to sceptical conclusions about the effects of discussion in improving knowledge of partner's attitude or in promoting approval.     

西藏人口与民族繁荣初探

本文在探讨民族繁荣的指标体系的基础上，分析了中国各少数民族人口发展与民族繁荣的状况，认为人口一教育一经济协调发展是民族繁荣的关键。并以此为研究视角，分析了建国以后西藏人口发展与民族繁荣的成就、问题和前景。     

关于我国人口教育概念的重新认定

本文通过对我国人口教育发展历程的回顾 ,提出重新认定人口教育教学内容问题 ,并试图通过整合课程途径来实现这一目标