农村老年人老化态度变动轨迹:基于积极老龄化框架的实证考察

基于积极老龄化理论框架和"中国老年健康影响因素跟踪调查"面板数据,文章从积极和消极两个维度对农村老年人老化态度问题进行实证考察。研究发现,两种老化态度均以2008年为重要转折点,女性老化态度比男性更具多样性和多变性。健康、社会参与和保障都能引起老化态度的积极变动,但社会适应、子女经济支持和社区照料三个因素对消极老化态度有正向影响,而生产活动降低了积极老化态度水平。从贡献率看,健康因素对老化态度差异贡献最大,其次是保障因素、社会参与因素,健康因素更能解释积极老化态度的变化,社会参与因素对消极老化态度的贡献率更高,二者分别在女性和男性老年人群体中表现得更为明显。贡献率排在前四位的因素是精神健康、子女经济支持、医疗可及性和身体健康。用积极老龄化的观点帮助庞大的农村老年人口建立正确的老化态度将有益于养老问题的解决。     

气藏水平井连续携液理论与实验

在气藏水平井中随着生产管柱倾斜角度的变化，井筒内液体的重力作用会发生改变，从而引起气液两相流型的变化。以产气为主的气井井筒内液体主要以液膜、液滴的形式出现，由此出现了液滴模型与液膜模型两种解释积液的理论。从这两种携液理论出发，考虑生产管柱倾斜角度的影响，对倾斜管内液滴、液膜进行受力分析，推导出了随管柱倾斜角度变化的连续携液临界流速的计算式，使之适用于水平井连续携液临界流量的计算。设计制作了水平气井连续携液实验装置并进行了实验研究，观测气藏水平井中气水两相运动与流型变化情况并测试其临界携液气量，结果表明，气藏水平井中水平井段的液体以液膜携带为主，但直井段中越接近井口，越以液滴携带为主，液滴模型也能适用于计算气藏水平井的连续携液临界流速。     

朝鲜族人口自然增长率下降对发展的影响

本文分析了朝鲜族人口减少的主要原因及负面影响,并提出了解决的对策.     

中国粮食增产的主要因素贡献分解与实证估算

已有测算中国粮食增产要素贡献率的方法存在虚增或低估某要素贡献率的缺陷,文章通过改进粮食增产贡献率测算方法实证估计了2003—2016年期间单产、播种面积和结构调整对中国粮食增产的贡献。结果表明,中国粮食实现“十二连增”的巨大成就主要是单产增长贡献,年均贡献率50%以上,播种面积和作物内部结构调整也是不可忽视的重要力量,年均贡献率分别为30%与10%以上。然而,未来中国粮食增产依靠播种面积扩大和结构调整的空间变窄,需要探索新的增产路径。     

Mixed-effects Models with Skewed Distributions for Time-varying Decay Rate in HIV Dynamics

After initiation of treatment, HIV viral load has multiphasic changes, which indicates that the viral decay rate is a time-varying process. Mixed-effects models with different time-varying decay rate functions have been proposed in literature. However, there are two unresolved critical issues: (i) it is not clear which model is more appropriate for practical use, and (ii) the model random errors are commonly assumed to follow a normal distribution, which may be unrealistic and can obscure important features of within- and among-subject variations. Because asymmetry of HIV viral load data is still noticeable even after transformation, it is important to use a more general distribution family that enables the unrealistic normal assumption to be relaxed. We developed skew-elliptical (SE) Bayesian mixed-effects models by considering the model random errors to have an SE distribution. We compared the performance among five SE models that have different time-varying decay rate functions. For each model, we also contrasted the performance under different model random error assumptions such as normal, Student-t, skew-normal, or skew-t distribution. Two AIDS clinical trial datasets were used to illustrate the proposed models and methods. The results indicate that the model with a time-varying viral decay rate that has two exponential components is preferred. Among the four distribution assumptions, the skew-t and skew-normal models provided better fitting to the data than normal or Student-t model, suggesting that it is important to assume a model with a skewed distribution in order to achieve reasonable results when the data exhibit skewness.     

Comparison of hazard rates for dependent random variables

In this paper, we define and study a new notion for the comparison of the hazard rates of two random variables taking into account their mutual dependence. Properties, applications and the comparison for a data set are given.     

Understanding Estimators of Treatment Effects in Regression Discontinuity Designs

In this paper, we propose two new estimators of treatment effects in regression discontinuity designs. These estimators can aid understanding of the existing estimators such as the local polynomial estimator and the partially linear estimator. The first estimator is the partially polynomial estimator which extends the partially linear estimator by further incorporating derivative differences of the conditional mean of the outcome on the two sides of the discontinuity point. This estimator is related to the local polynomial estimator by a relocalization effect. Unlike the partially linear estimator, this estimator can achieve the optimal rate of convergence even under broader regularity conditions. The second estimator is an instrumental variable estimator in the fuzzy design. This estimator will reduce to the local polynomial estimator if higher order endogeneities are neglected. We study the asymptotic properties of these two estimators and conduct simulation studies to confirm the theoretical analysis.     

中国农村民间借贷市场融资约束环境下利率定价模型分析——以广东农村实地调查数据为例

通过对广东农户民间借贷行为实地调查的问卷进行数据分析,了解农村民间借贷中的资金供求关系,发现存在的融资约束问题,进而对融资约束环境下民间借贷资金利率定价过程进行实证分析;着重考察农村民间借贷利率受公共信息和私人信息影响的程度,从借款人和贷款人的角度分别建立定价模型进行经验分析。结果显示,定价模型在F检验1%水平上显著,其他模型具有R2的统计显著性;反映借款用途的变量在10%水平上显著,其他变量均在5%水平上显著。这说明该市场利率能够反映公共信息的影响,借款人和贷款人的利率定价也反映了各自私人信息中相关风险和财务能力因素的影响,得到的经验结论主要是:第一,农村民间借贷市场是自主交易的金融市场;第二,其利率定价过程基本市场化。     

Who cares? A lack of self‐care for women in the non‐profit/non‐governmental sector

In this article I examine the lack of self‐care regimes for women working in the non‐profit/non‐governmental sector. While I draw on ethnographic research conducted in the Malaysian context of women's organizations, the issue of self‐care for activists and feminist activists is a global one that crosses borders and boundaries. I explore the gendered nature of care and care professions to demonstrate how women are predominantly affected in these working environments. To date, there has been little scholarship on self‐care and care in non‐profit/non‐governmental working environments. Using interviews with women working in the sector, I argue that women's emotional, mental and physical health comes at a cost in these hectic workplaces. This article contributes to the literature on gender, work and care in women's organizations by taking seriously women's concerns working in these spaces, where they experience self‐neglect and institutional barriers in care regimes.