中国农村养老政策的历史回顾与展望

由于长期的城乡二元体制,我国农村养老事业的发展远落后于城市,农村养老政策的欠完善成为影响农村养老问题解决的重要因素.回顾新中国成立以来我国农村养老政策的发展历程,将其分为萌芽时期、转型时期和发展时期三个发展阶段,并重点分析了五保供养制度、农村养老保险制度、农村合作医疗制度、最低生活保障制度等特殊养老制度,在此基础上提出了农村养老政策的未来展望.     

Estimation for Partially Linear Single-index Instrumental Variables Models

In this article, we generalize the partially linear single-index models to the scenario with some endogenous covariates variables. It is well known that the estimators based on the existing methods are often inconsistent because of the endogeneity of covariates. To deal with the endogenous variables, we introduce some auxiliary instrumental variables. A three-stage estimation procedure is proposed for partially linear single-index instrumental variables models. The first stage is to obtain a linear projection of endogenous variables on a set of instrumental variables, the second stage is to estimate the link function by using local linear smoother for given constant parameters, and the last stage is to obtain the estimators of constant parameters based on the estimating equation. Asymptotic normality is established for the proposed estimators. Some simulation studies are undertaken to assess the finite sample performance of the proposed estimation procedure.     

轻与重：美丽的悔——读张枣《镜中》

张枣很早就开始尝试对古典诗学传统的吸收和借鉴,并进行了比较成功的试验,《镜中》便是一例。通感和＂词义借用＂使＂悔＂变得美丽轻盈,人称转换造成了心理空间腾挪,＂镜中＂这一出色运用的意象统摄了全诗,三者共同织就一个复杂的文本。这些技巧帮助平衡了诗中的轻与重,取得了良好的效果。     

On a system of nonhomogeneous components sharing a common frailty

The components of a reliability system subjected to a common random environment usually have dependent lifetimes. This paper studies the stochastic properties of such a system with lifetimes of the components following multivariate frailty models and multivariate mixed proportional reversed hazard rate (PRHR) models, respectively. Through doing stochastic comparison, we devote to throwing a new light on how the random environment affects the number of working components of a reliability system and on assessing the performance of a k-out-of-n system.     

关于中国现代史分期问题的思考

目前,史学界对于中国现代史的分期看法不一,形成不同的主张：或以重大政治历史事件为标准,或依据《关于建国以来党的若干历史问题的决议》,或以经济社会发展目标模式为分期标准。这些标准都不符合中国通史的学科分期要求。中国现代史作为通史,其分期应当以社会形态的变迁为标准,应根据社会主义的不同发展模式,将其划分为新民主主义时期或社会主义的准备时期、苏联模式社会主义时期或传统社会主义时期、中国特色社会主义时期或现代社会主义时期。     

Re-Defining the Who,When, and Where of Mentoring for Professional Statisticians

Organizations tailor their mentoring strategies to accommodate internal resources and preferences, producing different approaches in academic, government, and corporate environments. Across these settings, three common barriers impede effective mentoring of statisticians: overspecialization, time constraints, and geographic dispersion. The authors share mentoring strategies that have emerged at their organization, Mathematica Policy Research, to overcome these obstacles. Practices include creating a methodology working group to unite researchers with diverse backgrounds, integrating mentoring into existing workflows, and harnessing modern technological infrastructure to facilitate virtual mentoring. Although these strategies emerged within a specific professional context, they suggest opportunities for statisticians to expand the channels through which mentorship can occur.     

时代交替视野下的明代“北虏”问题

无论是在世界史还是在东亚史上,16世纪都是一个重要的时代。正是在这时,明朝深为"北虏南倭"问题所困扰。学界以往对明代"北虏"问题的解释框架,基本上局限于传统的游牧民族与农耕民族冲突史及明蒙关系史。在与其相提并论的"南倭"问题得到新的解释并被置于一个更广阔的海洋贸易史框架后,对"北虏"问题的认识变化依然不大。事实上,在长城沿线发生的、以明朝和蒙古为主角的一系列事件,同样是全球史时代变化的组成部分。这使我们认识到,"内陆史视角"的观察与思考应成为传统的"海洋史视角"的重要补充。     

Quantile regression and variable selection for the single-index model

In this paper, we propose a new full iteration estimation method for quantile regression (QR) of the single-index model (SIM). The asymptotic properties of the proposed estimator are derived. Furthermore, we propose a variable selection procedure for the QR of SIM by combining the estimation method with the adaptive LASSO penalized method to get sparse estimation of the index parameter. The oracle properties of the variable selection method are established. Simulations with various non-normal errors are conducted to demonstrate the finite sample performance of the estimation method and the variable selection procedure. Furthermore, we illustrate the proposed method by analyzing a real data set.     

研发模式对企业创新的影响——知识基础的调节作用

 在创新日益呈现出复杂性、系统性和不确定性的背景下，企业对合作研发和内部研发两种研发模式的合理选择及组合运用是提升创新效果的重要途径，但目前的相关研究仍存在一定局限性。一方面，合作研发和内部研发两种研发模式对不同类型创新(如突破式创新和渐进式创新)的影响机理和影响效果是否存在差异还未被厘清；另一方面，企业层面特征(如知识基础)对企业研发模式与企业创新关系的调节作用在已有研究中较少涉及。        针对上述研究现状和现实背景，整合知识基础观和创新管理相关理论，采用层级回归分析方法，收集310家制造企业数据，进行实证分析，研究企业合作研发和内部研发对其突破式创新和渐进式创新绩效的作用机理，以及知识深度和知识宽度对企业研发模式与企业创新关系的调节作用。        研究结果表明，相对于内部研发，合作研发对突破式创新绩效的影响更突出；相对于合作研发，内部研发对渐进式创新绩效的作用更为明显。知识深度在合作研发对突破式和渐进式创新绩效的影响中起正向调节作用，并正向调节内部研发与渐进式创新绩效的关系，但负向调节内部研发与突破式创新绩效的关系；知识宽度在内部研发对突破式和渐进式创新绩效的影响中起正向调节作用，并正向调节合作研发与突破式创新绩效的关系，负向调节合作研发与渐进创新绩效的关系。        在理论层面，考虑了不同研发模式对不同创新类型的影响，丰富了研发模式与企业创新领域的研究成果；引入知识基础作为调节变量，也为研发模式与企业创新之间权变因素的研究做出增量贡献；跳出了相关研究中关于合作研发与内部研发究竟是替代性还是互补性关系的争论，为后续研究提供了新思路。在管理实践层面，企业应根据自身的知识基础以及期望提升的创新类型来选择合适的研发策略。     

全球一体化催生的一株诗坛奇葩——中韩生态环境诗兴起脉络初探

西方发达国家于20世纪60年代产生的生态文学,在东西方冷战结束后,影响到了中韩两国的诗歌创作,20世纪80年代后,中韩两国诗坛上先后兴起生态环境诗。虽然中韩在社会基础、诗歌自身发展等因素上存在着各自差异,但在全球一体化的语境下,生态环境诗则形象地表达了两国诗人对工业文明的共同思考。