山区公路交通流特性分析与评价

首先由观测数据确定代表车型的运行速度,采用实际路段调查得到的运行速度作为评价指标,分析山区公路的交通流运行状况,然后通过实地调查采集山区公路典型断面的交通流数据,统计交通量、交通组成以及不同车型运行速度的分布情况,并通过分析交通组成以及车速连贯性和离散性等直接影响道路交通安全的因素,对事故多发路段的交通流运行状态特征进行分析和评价。最后,选取京昆高速公路某典型路段,对该路段的交通流特性进行分析与评价,可为相关工作人员提供借鉴和帮助。     

A Global Ex-vessel Fish Price Database: Construction and Applications

Synopsis We describe the first effort at creating a global ex-vessel fish price database, which is required for understanding the economic behavior of participants in the world’s fisheries. We demonstrate potential applications of the database by linking it to a spatially defined catch database, which makes it possible to attach landed values to species in both time and space. This is the first database available publicly where interested members of the public, researchers and managers can easily find and access ex-vessel prices of the world’s major commercial fish species. Preliminary results indicate that the average real price of a number of species have declined between 1950 and 2002. The estimated landed value of fish globally, in year 2000 dollars, was about US$24 billion in 1950. It increased steadily to about US$90 billion in the early 1970s, reached a peak of US$100 billion at the end of the 1980s, and declined to about US$80 billion in 2000. The top 15 fishing countries cumulatively account for 79% of total real landed value, with Japan leading, even though the value of its landings has been declining.      

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。     

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.     

新疆贫困地区经济发展因素综合分析

贫困人口问题始终是关系到社会稳定和地区发展的重要问题。地处我国最西部的新疆地区的贫困人口更是与边疆稳定、团结少数民族等政治目标相联系。随着乡镇企业、非公有制经济及农业产业化经营的迅速发展,吸收消化了贫困地区农村大量剩余劳动力,改变了单纯农业结构,提高了农产品加工和服务业在贫困地区经济中所占比重,增加了财政收入。此外,随着西部大开发战略的实施以及第二欧亚大陆桥的沟通,新疆的外向型经济和旅游业也得到了空前未有的发展。这些成就在新疆贫困人口脱贫致富道路上起着很大的作用。但是有部分地区变化不大,有的则出现了反复,贫困状况未能得到根本改变。这些贫困地区的存在,始终影响着新疆经济的可持续发展。文章分析了其贫困特征及原因,指出这些地区脱贫致富的主要途径。     

上市公司控制权争夺的动机及其特征

本文结合国内外研究成果以及我国当前的市场环境,对可能成为控制权争夺目标的公司会具备什么样的财务特征、股权结构以及公司治理进行了分析,以寻找上市公司控制权争夺的真正动机和目的.我们研究发现:上市公司经营业绩越差,债务比率越高,当年具有增发或配股资格,产权的可转让性越低,产权性质为国有企业和终极控制人为国有企业或政府机构时,其控制权被争夺的可能性也越高.