Mortality,Human Capital and Persistent Inequality

Available evidence suggests high intergenerational correlation of economic status and persistent disparities in health status between the rich and the poor. This paper proposes a mechanism linking the two. We introduce health capital into a two-period overlapping generations model. Private health investment improves the probability of surviving from the first period of life to the next and, along with education, enhances an individual’s labor productivity. Poorer parents are of poor health, unable to invest much in reducing mortality risk and improving their human capital. Consequently, they leave less for their progeny. Despite convex preferences and technologies, initial differences in economic and health status may perpetuate across generations when annuities markets are imperfect.Additional support was provided by the National Science Foundation. Additional support was provided by the National Science Foundation.     

The nature of the steady state in models of optimal growth under uncertainty

Summary. We study a one-sector stochastic optimal growth model with a representative agent. Utility is logarithmic and the production function is of the Cobb-Douglas form with capital exponent . Production is affected by a multiplicative shock taking one of two values with positive probabilities p and 1-p. It is well known that for this economy, optimal paths converge to a unique steady state, which is an invariant distribution. We are concerned with properties of this distribution. By using the theory of Iterated Function Systems, we are able to characterize such a distribution in terms of singularity versus absolute continuity as parameters and p change. We establish mutual singularity of the invariant distributions as p varies between 0 and 1 whenever . More delicate is the case . Singularity with respect to Lebesgue measure also appears for values such that . For and Peres and Solomyak (1998) have shown that the distribution is a.e. absolutely continuous. Characterization of the invariant distribution in the remaining cases is still an open question. The entire analysis is summarized through a bifurcation diagram, drawn in terms of pairs .Received: 9 April 2002, Revised: 29 October 2002, JEL Classification Numbers: C61, O41.Correspondence to: Tapan MitraThis research was partially supported by CNR (Italy) under the "Short-term mobility" program and by M.U.R.S.T. (Italy) National Group on "Nonlinear Dynamics and Stochastic Models in Economics and Finance" . We are indebted to Rabi Bhattacharya for providing us with the reference to Solomyak's (1995) paper. The present version has benefitted from comments by Mukul Majumdar and two anonymous referees.     

城乡居民收入差距的动态演变:1988～2002年

中国城乡居民收入差距已经引起广泛关注。文章以住户调查数据为基础,利用泰尔指数分解、G.Fields分解、Blinder分解、分位回归分解等多种方法讨论了1988年、1995年和2002年“城乡”因素本身对城乡居民收入差距的贡献。这些分解结果表明我国的城乡差距较显著并在不断扩大;而且城乡差距更不利于农村中的低收入人群。     

商业模式创新途径探讨

如今商业环境变化迅速,持续地获得利润已经成为企业关注的焦点,商业模式给企业提供了参考的思维方法与实践框架。商业模式的组成要素包括:为谁,做什么,如何做,如何盈利四部分。其创新的途径主要有重新定义顾客,提供特别的产品/服务,改变提供产品/服务的路径,改变收入模式,改变对顾客的支持体系和发展独特的价值网络。企业有必要适时创新自身的商业模式,保证持续地盈利,获得竞争优势。     

Optimization of Harvesting Return from Age-Structured Population

Synopsis Maximization of the net profit from harvesting in a one-species age-structured population is analyzed. One of the control functions is the age of harvested individuals. The constructed mathematical model is similar to vintage capital models used in economics for optimal capital replacement. The optimization technique developed by authors for the capital replacement is disseminated to the formulated problem. A qualitative analysis of the problem is provided and the interpretation of results is given. Such economic topics as a zero-investment period, optimal balanced growth, and turnpike properties are discussed.     

泰山旅游需求时空分布规律及旅游者行为特征的初步研究

泰山旅游需求存在着明显的时空分布规律．调查显示．游人数量的日变化、周变化和年内变化十分显著；客源地主要分布于山东及其周边省市；旅游区内部以泰山中路和岱顶的需求强度最大。最后对旅游交通方式、旅游消费、旅客职业构成双重游率等旅游者行为特征进行了分析。     

Coping with Technological Change: The Role of Ability in Making Inequality so Persistent

This study provides an explanation to the evolution of wage inequality over the last 30 years and supports this explanation with evidence. A faster rate of technological progress introduces new unknown elements at the workplace. The need to cope with the unknown accentuates the role of ability and thus increases wage inequality within and between education groups. Inasmuch as education is an irreversible investment project the rise in within group inequality BOOSTS UP the rise of between group inequality. Guided by this theory we turn to the PSID for evidence. Using parents' education to approximate child's ability we show the following set of results: (a) Controlling for education of the child, parents' education contributed much more in the 1980s to his wage growth than in the 1970s. (b) The correlation between the parents' and the child's education increases from the 1970s to the 1980s. (c) The return to college education for an individual with no ability rents did not change—it remains steady at the 23 percent. (d) Facts (a)–(c) CANNOT be attributed to the impact of parent's income. It is parents' education and not parents' income that is more relevant for son's economic outcomes in the 1980s.     

城市密集区人口变动研究——以长江三角洲、珠江三角洲和京津唐地区为例

利用第三、四和五次全国人口普查资料,对长江三角洲、珠江三角洲和京津唐地区人口增长和空间分布的变化过程进行分析.研究表明,自1980年代以来,各城市密集区人口增长速度加快,人口规模不断扩大;空间分布变化幅度大,总的趋势是集中化、不均衡化;人口变动状况具有阶段性差异;外来人口的迁移流入是人口变动的主导因素.在此基础上,探讨了城市密集区发展过程中的人口演化趋势以及人口变动规律,其结论是:城市密集区人口变动遵循逻辑斯蒂增长规律、波动推进规律、圈层扩散与等级扩散规律,人口增长将由高速到低速,人口分布将由集中化迈向相对地均衡化.     

激励扭曲与努力的无效分配——基于银行客户经理制模拟利润考核的有效性分析

文章首先通过运用多任务委托代理模型分析商业银行模拟利润考核制度的激励效应和扭曲效应,以及可能导致客户经理努力的无效分配;然后扩展分析银行模拟利润考核的有效性和模拟利润成本之间的权衡以及模拟利润的最优精确水平;最后结合我国商业银行的现实状况引申出与商业银行客户经理模拟利润考核制度相关的结论与政策建议。     

Environmental regulation and profitability: An application to Swedish pulp and paper mills

In this paper we analyze the impact on firm profits of the environmental regulations in the Swedish pulp and paper industry. The approach taken is a non-parametric programming model of the technology. A feature of this industry is that environmental regulations are determined individually for each mill. A question, then, is if these individual regulations have a similar impact on firm profits. The approach in this paper allows us to calculate both the regulated and unregulated profits, which means that the severity of the regulations, in terms of foregone profits, can be calculated for each mill. The empirical result shows that the impact on the mills varies substantially, and that the burden from the regulations is less severe in 1990 than in 1989.