Mortality modeling: A review

Looking at survival in terms of biological indicators of aging has given rise to various models of mortality, some of which we review here. The most notable models are that of Strehler and Mildvan, which relates the force of mortality to the ability of organisms to compensate for stress, and that of Sacher and Trucco, which describes the role played by homeostatic forces in shaping the age‐specific pattern of mortality. The analysis of longitudinal data in aging studies now incorporates the notions of heterogeneity and frailty, as well as that of changes in the “repair capacity”; of organisms. Furthermore, attention is now being paid to evolutionary theory and to models of senescence. These models and directions for further research are discussed.     

方本传奇《雷峰塔》中人与异类关系解读

方成培的《雷峰塔》在新的高度上对人与异类的故事进行了再认识,同时赋予白蛇完全不同于文明伦理的话语权利,使白蛇代表人的"本真存在"进行活动,由此揭示了文明环境下人的天性的难以为继的事实,从而具备了更高的认识价值。     

Nonparametric Discrete Choice Models With Unobserved Heterogeneity

In this research, we provide a new method to estimate discrete choice models with unobserved heterogeneity that can be used with either cross-sectional or panel data. The method imposes nonparametric assumptions on the systematic subutility functions and on the distributions of the unobservable random vectors and the heterogeneity parameter. The estimators are computationally feasible and strongly consistent. We provide an empirical application of the estimator to a model of store format choice. The key insights from the empirical application are: (1) consumer response to cost and distance contains interactions and nonlinear effects, which implies that a model without these effects tends to bias the estimated elasticities and heterogeneity distribution, and (2) the increase in likelihood for adding nonlinearities is similar to the increase in likelihood for adding heterogeneity, and this increase persists as heterogeneity is included in the model.     

A Semi-Nonparametric Approach to Model Panel Count Data

In count data models, overdispersion of the dependent variable can be incorporated into the model if a heterogeneity term is added into the mean parameter of the Poisson distribution. We use a nonparametric estimation for the heterogeneity density based on a squared Kth-order polynomial expansion, that we generalize for panel data. A numerical illustration using an insurance dataset is discussed. Even if some statistical analyses showed no clear differences between these new models and the standard Poisson with gamma random effects, we show that the choice of the random effects distribution has a significant influence for interpreting our results.     

Some partially variance balanced structurally incomplete row-column designs

Earlier results by the authors are used to provide the intrablock analysis for row-column designs that have observations at nodes of the row-column lattice, the design being structurally incomplete when some nodes are empty. Construction, properties, and intrablock analyses of some special b× b row-column designs with b empty nodes taken along the principal diagonal of the lattice are developed. The designs discussed have m > 1 associate classes and are said to be partially variance balanced. The special designs fall in two classes and are shown to be nearly optimal in a specified class of designs. A small catalog of designs constructed is provided and they should be useful when empty nodes do not represent wasted experimental units, perhaps because the row and column assignments of treatments are sequenced.     

Statistical vs. identified lives in benefit-cost analysis

Evaluation of projects that affect mortality risk usually assumes that risk changes are small and similar across individuals. In reality, risks differ among individuals and information about risk heterogeneity determines the extent to which affected lives are “statistical” or “identified” and influences the outcome of benefit-cost analysis (BCA). The effects of information about risk heterogeneity on BCA depend on, inter alia, whether information concerns heterogeneity of baseline or change in risk and whether valuation uses compensating or equivalent variation. BCA does not systematically favor identified over statistical lives. We suggest some political factors that may explain the apparent public bias.

复合词造词材料的语素化问题

复合词的造词法可以将语言系统内不同层级的成分整合在一起.在词义完整性的制约下,这些异质的材料只有取得语素层级的地位时,才能完成造词任务.本文以复合造词这一动态过程为关注点,认为复合造词材料在成词的过程中,有必要引入一个"语素化"的概念.     

互联网普及对果蔬特色产业发展促进农户增收的效果分析

为研究"互联网+"条件下果蔬特色产业发展对农户增收效应的相关问题,本文基于门槛回归模型,采用2007—2017年我国31个省级面板数据,实证分析了互联网普及对果蔬特色产业发展促进农户增收的效果及其区域差异。研究表明:(1)在全国层面上,果蔬特色产业发展对农户增收存在移动互联网普及率的双重门槛效应和宽带互联网普及率的单一门槛效应;(2)果蔬特色产业发展对农户增收的互联网门槛效应具有显著的区域异质性;(3)以宽带互联网为门槛时果蔬特色产业发展对农户增收所产生的门槛效应比以移动互联网普及率为门槛时更为显著;(4)2007—2017年我国农村人均果蔬特色产业产值与农村居民人均可支配收入的帕尔玛比值均有一定程度的下降,二者之间存在一定的正相关关系。本研究旨在探索"互联网+"条件下的产业融合与发展,以期为推动农业经济持续发展与农户增收致富提供微观实证依据。     

异质型人力资本与经济发展——基于空间异质性的实证研究

区域经济发展的不平衡性,始终是社会经济研究领域内的热点问题。不同层级的人力资本,应与区域的异质性相一致,以实现各自区域经济发展的最大化。本文在充分考量“四大板块”区域异质性基础上,以人力资本的异质性为视角,利用1987-2017年的省级面板数据构建多种空间面板计量模型,从经济增长和经济运行质量两个维度来探寻不同层次人力资本对区域经济发展效能的空间差异。研究表明：①全国层面,所有层次的人力资本对经济增长均有促进作用;但初级和中级人力资本会遏制产业结构高级化,只有高级人力资本才能推动产业结构高级化。②区域层面,不同层次的人力资本对东、中、西和东北地区经济发展的直接效应和间接效应具有明显的区域空间异质性。     

关于经济学的“基质”与演化方向的思考

自然性和社会性作为人类存在的基本性质,是任何科学研究的起点。经济学作为一门科学,其"基质"亦起源于人类这种基本性质。经济学"基质"的不同定位——同质性与异质性,决定了经济学不同存在方式及其相应作用方式。本文研究经济学基质的特殊性,由此说明经济学的本质是异质性的,并用经济学最近发展的实例印证这一分析结论。