对中国流动人口“梯次流动”的理论思考

针对中国大规模流动人口的流动特点及其流动过程进行理论思考,提出梯次流动概念和流动人口的梯次流动形式、前提条件和原理。将梯次流动定义为在流动迁移的过程中,流动人口凭借自身以及外部的力量不断改善其个人和家庭的福利状况,从而呈现出的一种渐进性的向上流动现象。梯次流动成为一种人口流动中不断优化决策的过程,梯次流动的实现需要一定的社会经济环境,中国近三十年来的改革开放和社会经济发展创造了必要的条件,促成了梯次流动动机的形成和实现的可能。梯次流动的分析视角有助于从微观视角分析个人流动到家庭流动迁移完成的过渡过程,更好地认识中国流动人口现象的特殊性并完善相应的政策与制度。     

人口老龄化阶段我国农村养老保险的机制创新

人口老龄化是当前全球人口结构发展的基本趋势。面对人口老龄化带来的各种挑战，加快建立和完善我国农特养老保险制度是一项紧迫的任务。廓清我国农村养老保险制度的困境及其成因与变迁，分析其中存在的问题，是推进农村养老保险制度改革的重要内容。从我国农村人口老龄化的趋势和农村经济发展的实际出发，通过机制创新，建立农村养老保险制度创新机制，是完善农村养老保险的关键所在。     

Stakeholders’ Perspective on Ecological Modeling in Environmental Risk Assessment of Pesticides: Challenges and Opportunities

The article closely examines the role of mechanistic effect models (e.g., population models) in the European environmental risk assessment (ERA) of pesticides. We studied perspectives of three stakeholder groups on population modeling in ERA of pesticides. Forty‐three in‐depth, semi‐structured interviews were conducted with stakeholders from regulatory authorities, industry, and academia all over Europe. The key informant approach was employed in recruiting our participants. They were first identified as key stakeholders in the field and then sampled by means of a purposive sampling, where each stakeholder identified as important by others was interviewed and asked to suggest another potential participant for our study. Our results show that participants, although having different institutional backgrounds often presented similar perspectives and concerns about modeling. Analysis of repeating ideas and keywords revealed that all stakeholders had very high and often contradicting expectations from models. Still, all three groups expected effect models to become integrated in future ERA of pesticides. Main hopes associated with effect models were to reduce the amount of expensive and complex testing and field monitoring, both at the product development stage, and as an aid to develop mitigation measures. Our analysis suggests that, although the needs of stakeholders often overlapped, subtle differences and lack of trust hinder the process of introducing mechanistic effect models into ERA.     

流动人口计划生育管理服务体系的缺陷与对策

流动人口计划生育管理服务工作是当前我国人口计生工作的难点。通过论述我国流动人口计划生育管理服务体系存在的理论缺陷、管理体制缺陷、融入缺陷、制度缺陷、机制缺陷、资源缺陷和手段缺陷,从战略层面、发展层面、工作层面提出提高流动人口计划生育管理服务效能的系列对策,以期能够破解困扰全国多年的流动人口计划生育管理服务难题。     

Economics of the firm and economic growth: a hybrid theoretical framework of analysis

Abstract

The main goal of this study is to achieve a critical discussion around the conceptualization of the firm and its role in the dynamic process of economic growth. By reviewing the theoretical matrix of the economics of the firm we go beyond the mainstream economics of the firm proposing a hybrid approach combining evolutionary and population ecology, which is likely to constitute a fruitful path for the conceptualization of the firm in the process of economic growth. Specifically, the analysis confronts the distinct theoretical perspectives around some imperative and controversial issues such as the nature of knowledge and learning and the cognitive capacities of economic agents within the firm. We argue that the economic understanding of growth and development of human societies will strongly benefit from a conceptualization of the firm capable of capturing the spirit of the Knightian firm. Overcoming the shortcomings of the mainstream growth models, which conceive firms as a black box, the proposed hybrid approach recalls the true nature of the firm as an organization. Issues related to the organizational arrangements that sustain the feasibility of productive activities and to the incentive contracts are also taken into account. Although acknowledging some recent important contributions within mainstream economic growth theory to adopt more realistic concepts of the firm, we believe that evolutionary and organizational population perspectives include crucial pointers in developing further research aimed at the construction of economic growth models based on a micro-economic perspective that is closer to the reality of firms.     

宁夏人口与生态环境面临的问题及对策

宁夏是少数民族地区，较为宽松的生育政策。导致人口快速增殖。由于宁夏所处的地理位置和历史遗留的生态债务使得境内生态环境十分脆弱。尤其是人口过度增殖已超出了刚性土地资源的有效容纳力。这不仅给环境造成了巨大压力，也进一步加剧了生态环境的恶化。本文通过大量统计数据和实地调研。分析了近年来宁夏人口与生态环境之间存在的亟待解决的矛盾和问题。分析表明，当前宁夏尤其是宁南山区人口数量与人口素质、人口数量与生态存量和生态消费之间表现出了明显的此长彼消的关系。在分析的基础上．提出了人口与生态环境建设方面的政策建议。     

An Exposure Assessment of Methyl Mercury via Fish Consumption for the Japanese Population

The objective of this article was to propose an exposure assessment model to describe the relationship between fish consumption and body methyl mercury (MeHg) levels in the Japanese population. Individual MeHg intake was estimated by the summation of species-specific fish consumption multiplied by species-specific fish MeHg levels. The distribution of fish consumed by individuals and the MeHg level in each fish species were assigned based on published data from Japanese government institutions. The probability of MeHg intake for a population was accomplished through a Monte Carlo simulation by the random sampling of fish consumption and species-specific MeHg levels. Internal body MeHg levels in blood and hair were estimated using a one-compartment model. Overall, the mean value of MeHg intake for the Japanese population was estimated to be 6.76 μg/day or 0.14 μg/kg body weight per day (bw/day), while the mean value for the hair mercury level was 2.02 μg/g. Compared with the survey data that tabulated hair mercury levels in a cross-section of the Japanese population, the simulation results matched the hair mercury survey data very well for women, but somewhat underestimated for men and all of the population. This exposure assessment model is a useful attempt at further risk assessment with respect to a risk-benefit analysis.     

中国各民族人口发展状况的度量

人口是社会生活的主体,人口发展是社会发展的重要组成部分。但度量社会发展的方法还存在一些难以解决的问题。利用现有的评价方法,尚不能全面准确地反映中国各民族人口发展的现状。为了更加全面准确地把握人口发展状态,构建了衡量人口发展的指标体系,按照这个指标体系,分析中国各民族人口的发展现状、各民族在发展过程中所处的位置,以及他们目前存在的突出问题。     

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。