略论古诗十九首的产生时问和作者阶层

古诗十九首应是建安十六年(211年)至魏明帝景初年间(约239年)之间的作品,其作者不可能是东汉下层文人。     

Healthy lower backs in the construction industry in Sweden

This corss-sectional study exmaines the relationship between healthy lower and psychosocial and physical factors in a random sample of 1773 male construction workers. Infoamtion on lower back status, lifestyle habits, stress, psychosomatic and psychological symptoms, psychosocizal demands and resoruces and physical workload were collected by means of a postal questionnaire. Measures of psycholocial and physical factors were based on factor analysis of the data. The criterion variable 'healthy lower back' (HLB)—no lifetime history of low back pain—proved to be valid compared with an interview and a physical examination. A total of 216 workers (12%) reported HLB. The prevalance rate decreased significantly with increasing age. The prevalence rate of HLB was 6% among workers reporting high stress levels. It was postively influenced when there was a balance between demands and resoruces. A low level of physical workload also increased the prevalence rate of HLB. When age, lifestyle and physical factors were kept constant in a multivariate analysis high scores on the discretions index and low scores on eh psychosomatic, psychological and stress indices cosntributed significantly to an increase prevalence rate of HLB.     

An improved algorithm for reliability bounds of multistate networks

Abstract

Indirect approaches based on minimal path vectors (d-MPs) and/or minimal cut vectors (d-MCs) are reported to be efficient for the reliability evaluation of multistate networks. Given the need to find more efficient evaluation methods for exact reliability, such techniques may still be cumbersome when the size of the network and the states of component are relatively large. Alternatively, computing reliability bounds can provide approximated reliability with less computational effort. Based on Bai’s exact and indirect reliability evaluation algorithm, an improved algorithm is proposed in this study, which provides sequences of upper and lower reliability bounds of multistate networks. Novel heuristic rules with a pre-specified value to filter less important sets of unspecified states are then developed and incorporated into the algorithm. Computational experiments comparing the proposed methods with an existing direct bounding algorithm show that the new algorithms can provide tight reliability bounds with less computational effort, especially for the proposed algorithm with heuristic L1.     

Uncertainty Shocks in a Model of Effective Demand

Can increased uncertainty about the future cause a contraction in output and its components? An identified uncertainty shock in the data causes significant declines in output, consumption, investment, and hours worked. Standard general‐equilibrium models with flexible prices cannot reproduce this comovement. However, uncertainty shocks can easily generate comovement with countercyclical markups through sticky prices. Monetary policy plays a key role in offsetting the negative impact of uncertainty shocks during normal times. Higher uncertainty has even more negative effects if monetary policy can no longer perform its usual stabilizing function because of the zero lower bound. We calibrate our uncertainty shock process using fluctuations in implied stock market volatility, and show that the model with nominal price rigidity is consistent with empirical evidence from a structural vector autoregression. We argue that increased uncertainty about the future likely played a role in worsening the Great Recession. The economic mechanism we identify applies to a large set of shocks that change expectations of the future without changing current fundamentals.     

奈特不确定性下的资产及其组合的惰性区间

不确定性是证券市场的基本特征之一,是资产定价和投资者交易行为等研究的主要内容。标准期望效用理论认为投资者具有唯一的资产执行价格,当市场价格高于执行价格时,投资者出售资产;反之,则会购进。然而,源于不确定性的存在,资产的均衡价格或交易价格并非某一确定值而是某一区间;在此区间内,投资者无交易行为,我们称之为资产的惰性区间。本文假定投资者是不确定性规避型,基于可行域上的容度,引入测度奈特不确定性程度的等级参数,研究奈特不确定性下的资产及其组合的惰性区间。基于容度期望效用模型,利用容度代替概率测度表征投资者预期效用,提出奈特不确定性下投资者决策行为的偏好表达式;基于对偶测度构建资产交易的惰性区间,分析奈特不确定性程度与惰性区间的关系;最后,基于Black-Scholes期权定价模型,选择存续期为2008年10月-2011年8月的江铜认购权证和长虹认购权证为研究对象,以其单资产及不同比例资产组合的日收益数据为样本予以实证。结果表明：随着奈特不确定性程度的不断增强（减弱）,资产及其组合的惰性区间不断扩大（缩小）,市场流动性随之下降（上升）;随着奈特不确定性程度的增强,高价格、高波动率的资产及其组合的惰性区间变化更为明显;在适度的奈特不确定性程度范围内,高波动率的资产及其组合的交易相对活跃。研究解释了证券市场上的“非市场参与”之谜和“特质波动率”之谜,说明了证券市场上的“有限市场参与”特征,为资产定价与市场流动性关系的研究提供了参考。     

期刊等级评（认）定的混乱及其负效应

目前期刊等级的评定呈现一种“齐抓共管”的混乱局面 ,带来诸多负面影响 ,对期刊业的发展十分不利。据此笔者认为应由新闻出版管理机关将评刊工作管理起来 ,建立一整套科学、规范、完备的评刊体系 ,使评刊工作健康有序的开展     

中国保险公司下侧风险状况研究——基于下端部分矩的实证分析

下端部分矩(LPM)是量度下侧风险的有效工具。本文将下侧风险的量度运用于我国保险业的实证研究,以资产收益率(ROA)作为收益指标,通过对比香港上市的三家保险公司在投资者不同风险偏好下的下端部分矩(LPM)的值,定量分析我国保险上市公司面临的风险状况,为进一步实现保险公司投资者的风险和收益最优权衡以及强化保险公司内部监管提供有效的工具。     

云南省当代大学生性现状研究及思考

通过对云南省7所大学1600名大学生进行问卷调查，辅以一定的个案访谈，发现云南省当代大学生性观念较为纯洁、性行为相对保守，性知识了解不够，但对恋爱行为趋于认同，初恋年龄日趋低龄化。目前云南省中学及高校的性教育效果甚微，高校对青年大学生的性教育有待进一步加强，并且有必要将对学生的性教育纳入学校教育教学计划。     

基于层次分析法的"年级主题 基础"大学生思想政治教育模式的构建

"年级主题 基础"思想政治教育模式是在分析了现有高校以政治理论课为主渠道,以网络教育和第二课堂活动为有效途径的大学生思想政治教育模式缺陷的基础上提出的。通过德尔斐咨询法从专家、家长、学生三个方面采集信息,然后利用层次分析法对"年级主题"和"基础"两部分的内容进行定量的分析规划,构建出"年级主题 基础"大学生思想政治教育模式。