A general model of insurance under adverse selection

Summary. This paper considers optimal insurance schemes in a principal-agent multi-dimensional environment in which two types of risk averse agents differ in both risk and attitude to risk. Risk corresponds to any pair of distribution functions (not necessarily ordered by any of the usual dominance relations) and attitudes to risk are represented by any pair of non-decreasing and concave utility functions (not necessarily ordered by risk aversion). Results obtained in one-dimensional models that considered these effects separately and under more restricted conditions, are preserved in the more general set-up, but some of the questions we study can only be posed in the more general framework. The main results obtained for optimal insurance schemes are: (i) Insurance schemes preserve the order of certainty equivalents; consequently, the latter constitute a one-dimensional representation of types. (ii) Agents with the lower certainty equivalent are assigned full insurance. Partial insurance assigned to the others may entail randomization. (iii) Partially insured positions are an increasing function of the ratios of the probabilities that the two types assign to the uninsured positions. Most of these properties are preserved when, due to competition or other reasons, the insured certainty equivalents can not be set below pre-determined levels. Received: January 13, 1998; revised version: October 10, 1998     

应用结点电压法应关注的几个问题

结点电压法是分析电路的常用方法之一。通过电阻电路图介绍了列写结点电压方程时会出现的各种情况,并进行了归纳总结。通过整理,有助于学生掌握该方法,而且更深入地理解和掌握电路等效变换和基尔霍夫电流定律。     

某成品油管道岩石挤压段顶部应力响应

利用X射线应力测试原理，对某成品油管道岩石挤压段顶部位置的轴向应力和环向应力进行测试，并计算对应的Mises等效应力。将移除岩石前后挤压管段的各种应力进行对比，结果表明：岩石挤压管段顶部的轴向应力为拉应力，环向应力为压应力，相同位置的轴向应力值大于环向应力值；轴向应力和Mises等效应力在管道轴向呈“W”状分布，环向应力在管道轴向呈“V”状分布；移除岩石后，轴向应力、环向应力以及Mises等效应力均有不同程度减小，其中轴向应力和Mises等效应力减小值曲线呈“倒V”状，环向应力减小值曲线则呈“V”状。     

Location-scale portfolio selection with factor-recentered skew normal asset returns

This paper analyzes the single period portfolio selection problem on the location-scale return family. The skew normal distribution, after recentering and reparameterization, is shown to be in this family. The recentered and reparameterized distribution, called factor-recentered skew normal, can be expressed as a skew factor model which is characterized by a location parameter and two scale parameters. Risk preference on scale parameter is non-monotonic and risk averse investors prefer larger (smaller) scale when the scale is negative (positive). The three-parameter efficient set is a part of conical surface bounded by two lines. Positive-skewness portfolios and negative-skewness portfolios do not coexist in the efficient set. Numerical cases under constant absolute risk aversion are analyzed with its closed-form certainty equivalent. An asset pricing formula which nests the CAPM is obtained.     

Filling a dietary data gap? Validation of the adult male equivalent method of estimating individual nutrient intakes from household-level data in Ethiopia and Bangladesh

Many researchers use data from Household Consumption and Expenditure Surveys (HCES) to estimate individual food and nutrient intake when individual dietary data are not available. They assume that food is allocated within households according to members’ proportional energy requirements relative to an adult male (called an adult male equivalent, or AME). This study sought to validate AME-based estimates of individual consumption of calories, protein, iron, and animal source protein (ASP) across 10 age-sex categories, using data from Bangladesh and Ethiopia containing both household and individual-level consumption data. The study also assessed the accuracy of adjusting for meal partakers and physical activity levels (PAL), and compared energy-weighted AMEs to nutrient-specific AME predictions.Energy AME-based predictions of nutrient intake were generally accurate within ten percentage points of individually reported intakes, but were less accurate for infants 6–23 months and children in Bangladesh than for other demographic groups. AME predictions were more accurate: (1) in Ethiopia than in Bangladesh, (2) for predicting intake of the three nutrients rather than ASP, (3) for estimating nutrient intake rather than adequacy, (4) using energy-weighted AMEs rather than nutrient specific weights, and (5) using moderate PAL for youth and adults rather than high PAL. Adjusting for meal partakers did not consistently improve the AME-based predictions. Energy based AME estimates from household data can produce a useful proxy of average intake for certain population subgroups, however individually measured dietary assessment remains the best approach to identify groups at risk of nutrient inadequacy.     

关于等价无穷小代换求极限的补充说明

利用等价无穷小代换方法求极限可以简化计算.教学中往往强调只有乘积因子才能进行等价无穷小代换,而“＋”“-”号连接的各部分可根据具体情况,在特定条件下利用等价无穷小代换求极限.     

重力勘探在四川某铜矿勘查中的应用

重力勘探是固体矿产勘查常用且效果较好的物探方法。在对四川某铜矿进行了大比例尺高精度重力测量后,进行了系统的数据资料处理和分析,并结合地质和其他物探方法的成果进行了综合研究,作出了找矿预测。结果与已知的钻孔成果相符合。     

求戴维宁等效电路的另一分析方法

在电路分析中,求戴维宁等效电路,需分二步求等效电路,第一步求开路电压Uoc,第二步求输入电阻Req。本方法仅需求出U,I的表达式,直接由表达式得到开路电压和输入电阻,在解电路题时方便简捷。     

The effects of physical activity calorie equivalent labeling on dieters' food consumption and post-consumption physical activity

Effective body weight management requires dieters to engage in healthy eating and physical activity. This research explores the influences of physical activity calorie equivalent (PACE) labeling on dieters' food consumption and post-consumption physical activity. PACE indicates the amount of physical activity required to burn off food energy intake. This labeling aims to raise awareness on energy balance by highlighting an immediate link between food intake and exercise. This research shows that when exposed to PACE labeling, dieters (but not non-dieters) reduce their food consumption, increase their post-consumption physical activity, and are considerably motivated to achieve energy balance. This occurs because PACE labeling active energy balance-goal for dieters and influences their food consumption and subsequent physical activity. Implications for consumer well-being and policymakers are discussed.