Marriage Settlements

French couples may choose between two types of marriage settlements governing asset ownership after a divorce or inheritance: common property or separate property. A cooperative model considers the marriage contract as a means of providing for widowhood of the less endowed spouse. A second model addresses the probability of divorce and the production of a marriage good. The common property contract then becomes a means of inducing the wife to invest in the marriage good. Choice of contract, labor supply and fertility are simultaneous. Empirically we find that characteristics of the spouses such as relative age or differences in endowments influence the choice. So do the expected number of children and the wife's labor supply decision. This last decision is also shown to be influenced by the chosen settlement, while fertility is not.
JEL classification : J 12; J 4; K 12     

土工实验中的液、塑限测定浅议

文章分析了当前土工实验中的液、塑限测定过程中应当注意的问题及其存在的问题,并论述了如何对其实验数据进行处理和分析的方法。     

钢板桩围堰在水位变动区和软弱地基中的应用

利用钢板桩作围堰,在水位变动区和软弱地基条件下,采取一定刚度的围护设施来满足深基坑的施工需要;成功地运用了一种既施工简便、节约材料又确保安全的围护结构。根据软土的特点和钢板桩的柔性特征,通过采用模拟基坑开挖过程,按照板桩墙围护结构的设计计算方法进行围堰设计,并通过实际施工中一定的控制措施和对围堰内力、变形监测,确保相邻建筑物和自身结构施工的安全。根据实际运用的效果监测表明,采用的钢板桩围堰,是可行而又较优的一种方案。     

氢化物发生-原子荧光光谱法测定痕量硒

研究了氢化物发生-原子荧光光谱法测定土壤和水样品中的痕量硒,系统地考察了HCl浓度、KBH4浓度的影响;确定了最佳测定条件;共存元素的影响及干扰的消除,硒的回收率为95%～102%,硒的检出限为0.18ng/mL,RSD小于4%。本法用于测定标准土壤和水样品中的硒,结果与标准值吻合。     

山东省水土流失经济损失与生态价值损失评估

介绍了山东省水土流失现状，分析其危害，重点探讨了水土流失经济损失和生态价值损失的计算方法，建立经济损失计算模型，提出水土流失生态一经济面积边际比的概念，计算山东省县域边际损失比，并对其进行区域分布规律分析。     

我国西南地区水土治理及西部大开发的实证研究

无论是从问题的实质,还是方法论的角度来讲,水土治理都是西南地区经济开发中的一项战略性工程。通过对云南省红河州具体的水土流失现状、危害和治理的紧迫性和治理中存在的主要问题的分析,提出了西南地区水土治理的总体战略设想和具体的治理措施。     

Pollution Externalities in a Model of Endogenous Fertility and Growth

An endogenous growth model with human capital formation, pollution caused by production of consumption goods, and endogenous fertility decisions made by altruistic agents with infinite horizons is presented. Consequences for optimal policy of modelling fertility as an explicit decision variable are examined. Because ordinary lump-sum transfers to individuals are no longer neutral, either revenue from a pollution tax must be redistributed to dynasties (working as an implicit tax on child births), or lump-sum transfers must be supplemented with an explicit fertility tax. Alternatively, the government can avoid distortions of the fertility decisions by maintaining an appropriate public debt. When abatement is highly productive, it can be optimal to subsidize fertility in order to increase total production.     

Population Aging and the Possibility of a Middle-Income Trap in Asia

We present three conditions for a demography-driven middle-income trap and show that many economies in East, South, and Southeast Asia satisfy all of them. The conditions involve (1) the support ratio of workers to consumers has an impact on economic growth, (2) economic development accompanies more investment in human capital and lower fertility due to the quantity–quality trade-off, and (3) a current low level of fertility corresponds to very low support ratios for keeping up with frontier economies in the long run. Panel analysis for 178 countries shows that (1) and (2) are satisfied for Asia with higher elasticity than others. As for (3), we set up a dynamic model for simulations, showing that approximately two-third of Asia’s developing countries have an unsustainable level of support ratios, implying possibility of a middle-income trap due to future demographic headwinds.     

大兴安岭森林火烧对土壤生境质量影响研究

森林火烧是一种自然或人为因素产生的干扰,能够改变当地土壤的物理性质、化学性质及生物指标,对土壤的性质与土壤的肥力影响较大,对农业生态系统的结构与功能影响深远。作为我国重点的国有林区,大兴安岭地区林地面积广阔,森林覆盖率高,是我国生态安全的重要保障区,拥有丰富的林业资源,林下适生农业经济作物有500多种,林木、柞蚕、林果及中草药等绿色种养产业的资源十分丰富,是当前大兴安岭发展现代农业的主要模式。大兴安岭是我国森林火灾的多发区,文章对近年来国内专家学者对火烧影响森林土壤的理化性质与生物指标等众多研究成果进行综合评述,近年来,研究者从大兴安岭不同地区、不同林火种类与林火强度系统分析并研究了火烧对土壤生境质量的影响,该文通过对其进行归纳总结,旨在为该地区的火烧迹地植被恢复及农业林下经济的科学经营管理提供科学依据。     

基于地统计学和空间自相关的土壤有机质空间异质性分析及分区土地整治视角

目的 土壤指标是耕地质量分等的依据,其空间异质性和空间自相关性对土地整治分区,以及土地平整工程中的表土剥离、移土培肥和土壤改良等关键技术的实施都具有重要作用。方法 文章以渝西丘陵区的典型基本农田建设区为研究区,综合运用地统计学与Kriging插值法研究0~20cm、20~40cm和40~60 cm土层土壤有机质（SOM）的空间异质性,结合全局和局部空间自相关分析法分析各土层SOM的空间自相关性,并基于LISA聚类图进行SOM分区,进而提出土地整治的应用建议。结果 （1）研究区3层SOM平均含量处于全国第二次土壤普查土壤养分分级标准的4级,为中等水平。（2）20~40 cm土层SOM的最优模型为球面模型,其余两层均为高斯模型,3层SOM均属于中等变异,受结构性和随机性因素的共同影响,在空间上呈不规则的斑状与块状分布。（3）3层SOM均表现为显著的正空间自相关性及空间集聚特征,高—高（HH）集聚区分布在平坝与丘间谷地,主要为水田,这与水田更有利于SOC的贮存和提高土壤的固碳能力有关,其次为旱地;低—低（LL）集聚区主要分布在南部丘陵区,土地利用类型表现多样化,故丘陵区需重视土壤改良。（4）以表层SOM空间自相关分布特征为主,中、下层为辅,将研究区划分为高SOM集聚区、表层高SOM集聚区、低SOM集聚区和SOM随机分布区4个分区,根据不同分区间SOM含量差异和空间集聚特征,提出了不同的土地整治建议。结论 研究结果体现了SOM含量在剖面和水平空间上高值与低值的集聚特征,更有利于针对性地采取土地整治措施,可作为土地整治分区的重要参考。