沈阳市老年人口现状及其养老保障模式的构建

沈阳作为一个重工业城市 ,在其二次创业过程中人口老龄化问题日益突出 ,因此 ,掌握沈阳市老年人口的生活状况 ,构建适合沈阳市老年人口现状的养老保障模式 ,已经成为沈阳市社会养老保障体系改革的重要内容。     

"离农"与韩国农业的现状

韩国自 194 5年独立到 1999年间 ,伴随着工业化的高速进展 ,农村人口也大量流失 ,占总人口的比重由 70 %下降到 9%,使得目前的农村劳动力严重不足与老龄化。人口的减少与剧烈的两极分化 ,使出租地增加到总耕地面积的 4 0 %以上 ,而且基本上是土改前租佃关系的翻版 ,不利于机械化与生产效率的提高。由于农业危机 ,韩国政府希望通过建立股份化的农场 ,使农业生产规模化、现代化 ,并为此做了很多努力 ,但进展不太顺利。     

可持续发展与人口老龄化

从人口自身来讲 ,一是数量要适度 ,二是素质要提高 ,三是结构要合理。人口应始终保持与系统其他要素的协调而不断调整自身的数量、质量与结构。老年人共享社会经济发展成果是实现可持续发展的重要条件 ,文章从 4个方面展开论述 :正确评估老年人创造社会财富的突出贡献 ;充分肯定老年人在发展文教、科技等各项事业中不可替代的巨大作用 ;不要忘记老一代为推动社会进步所付出的沉重代价 ;公平体现老年人一生的社会价值。     

Race and Population Change: A Longitudinal Look at Cleveland Neighborhoods

This paper investigates the relationship of racial composition to neighborhood population change from 1910 to 1990 in the Cleveland metropolitan area. To better understand the long-term dynamics of urban neighborhood change, we focus our analysis upon the longitudinal relationship of race, socioeconomic status, and life cycle stage to changes in neighborhood population densities. First, we find that the more established neighborhoods of the African-American community have experienced dramatic declines in population since 1950, a pattern that represents a clear change from the earlier part of the twentieth century. Second, population loss is experienced through a variety of mechanisms, including the demolition of dwellings, the increase in housing vacancy, and the decline of household size. Third, much of this population loss should be interpreted within the context of high economic distress, occurring most frequently in older African-American communities. Over time, economic distress appears to be more important than race in and of itself in leading to the loss of neighborhood populations.     

Sampling Strategies for Toxic Air Contaminants

Annual concentrations of toxic air contaminants are of primary concern from the perspective of chronic human exposure assessment and risk analysis. Despite recent advances in air quality monitoring technology, resource and technical constraints often impose limitations on the availability of a sufficient number of ambient concentration measurements for performing environmental risk analysis. Therefore, sample size limitations, representativeness of data, and uncertainties in the estimated annual mean concentration must be examined before performing quantitative risk analysis. In this paper, we discuss several factors that need to be considered in designing field-sampling programs for toxic air contaminants and in verifying compliance with environmental regulations. Specifically, we examine the behavior of SO2, TSP, and CO data as surrogates for toxic air contaminants and as examples of point source, area source, and line source-dominated pollutants, respectively, from the standpoint of sampling design. We demonstrate the use of bootstrap resampling method and normal theory in estimating the annual mean concentration and its 95% confidence bounds from limited sampling data, and illustrate the application of operating characteristic (OC) curves to determine optimum sample size and other sampling strategies. We also outline a statistical procedure, based on a one-sided t-test, that utilizes the sampled concentration data for evaluating whether a sampling site is compliance with relevant ambient guideline concentrations for toxic air contaminants.     

BATHTUB-TYPE CURVES IN RELIABILITY AND BEYOND

Finding optimal, or at least good, maintenance and repair policies is crucial in reliability engineering. Likewise, describing life phases of human mortality is important when determining social policy or insurance premiums. In these tasks, one searches for distributions to fit data and then makes inferences about the population(s). In the present paper, we focus on bathtub‐type distributions and provide a view of certain problems, methods and solutions, and a few challenges, that can be encountered in reliability engineering, survival analysis, demography and actuarial science.     

An alternative to model selection in ordinary regression

The weaknesses of established model selection procedures based on hypothesis testing and similar criteria are discussed and an alternative based on synthetic (composite) estimation is proposed. It is developed for the problem of prediction in ordinary regression and its properties are explored by simulations for the simple regression. Extensions to a general setting are described and an example with multiple regression is analysed. Arguments are presented against using a selected model for any inferences.     

中国人口性别结构的区域差异及演变动态分析

人口性别构成是影响人类婚姻、人口再生产的基本因素，也影响国家经济、政治、文化、教育等方面的发展，也是编制经济、文化、教育、科技、卫生、人民生活、劳动、城乡建设等发展规划的重要依据。同时对于中国当前正在进行的和谐社会建设也具有重要意义。利用中国五次人口普查资料及2005年1％人口抽样资料分析了中国总人口性别比演变动态及地理分布特征。表明：（1）中国在历史上是一个性别比偏高的国家，新中国总人口性别比呈下降趋势；（2）1953到2005年，年龄性别比曲线越来越平稳，性别比最高峰值呈现有低龄组向中龄组及高龄组转移的趋势；（3）各省区之间及城乡之间的性别结构差异由大变小；（4）山区性别比高于平原。重工业城市高于其他城市。大城市高于小城市。     

钢管相邻缺陷漏磁场相互影响的分析

实际工况中的管道缺陷是非常复杂的,用物理试验的方法研究各种缺陷漏磁场的变化规律有一定的难度。该文针对油气管道常用的钢管缺陷产生的漏磁场建立了三维有限元模型,采用有限元方法计算了几种相邻缺陷的漏磁场模型,给出了计算结果,并分析了各种相邻缺陷对漏磁场信号的影响。结果表明当相邻缺陷的中心线与磁场方向平行时,对缺陷漏磁信号的影响最小;组合型的缺陷对漏磁信号的影响最大。