粮食中镉含量测定方法初探:以石墨炉原子吸收分光光度计法为例

笔者长期从事粮食中镉污染检验工作,大量实践经验表明,虽然原子吸收仪的品牌、型号各不相同,但应用原理、结构大致相同。本文以石墨炉原子吸收分光光度计法对粮食中镉的含量的检测为例进行说明,发现试样前处理、试剂空白、使用试剂、回收实验及在操作过程中的对仪器的处理等对检测结果均会产生直接影响。为确保检测结果准确性,本文对检测过程中影响检测结果的各注意事项进行了分析总结,希望能对从事镉污染检测工作的人员提供理论指导和借鉴。     

Who Herds? Who Doesn't? Estimates of Analysts’ Herding Propensity in Forecasting Earnings

We develop parametric estimates of the imitation‐driven herding propensity of analysts and their earnings forecasts. By invoking rational expectations, we solve an explicit analyst optimization problem and estimate herding propensity using two measures: First, we estimate analysts’ posterior beliefs using actual earnings plus a realization drawn from a mean‐zero normal distribution. Second, we estimate herding propensity without seeding a random error, and allow for nonorthogonal information signals. In doing so, we avoid using the analyst's prior forecast as the proxy for his posterior beliefs, which is a traditional criticism in the literature. We find that more than 60 percent of analysts herd toward the prevailing consensus, and herding propensity is associated with various economic factors. We also validate our herding propensity measure by confirming its predictive power in explaining the cross‐sectional variation in analysts’ out‐of‐sample herding behavior and forecast accuracy. Finally, we find that forecasts adjusted for analysts’ herding propensity are less biased than the raw forecasts. This adjustment formula can help researchers and investors obtain better proxies for analysts’ unbiased earnings forecasts.     

阻断性压力源与工作-家庭冲突:谦卑和学习目标导向的调节作用

基于资源保存理论和压力交互模型,本研究探讨了阻断性压力源对工作-家庭冲突的影响及其边界条件.对国内120名企业员工的数据分析结果表明,阻断性压力源正向影响工作-家庭冲突,除此之外,谦卑和学习目标导向共同调节了阻断性压力源和工作-家庭冲突之间的关系,具体地,当谦卑和学习目标导向均高的时候,阻断性压力源与工作-家庭冲突之间的正向关系最弱;相反,对于谦卑和学习目标导向均低的个体来说,阻断性压力源对工作-家庭冲突的正向影响最强.     

Shanxi Merchants’ Multilevel Financial System in Ming and Qing Dynasties,China

In the Ming and Qing Dynasties (1368–1911), China saw rapid development in industrial and commercial sectors. Over this period, a group of merchants originating from the inland province of Shanxi gradually built a multilevel financial system and became leaders in China’s banking sector. The system of financial institutions they established (pawnshops, seal shops, money shops, loan banks, and draft banks) each had a unique business model, with specific target client group and carefully designed risk management. They were also interconnected to allow for flexible capital flows, contributing to the fast economic growth in this period. Nevertheless, the traditional system also had limitations, leading to its replacement by modern banks eventually.     

Carbon Markets in China: Development and Challenges

China is attempting to initiate its own carbon market—an important market-based policy instrument which would determine the fate of global climate policy as the largest emitter of carbon dioxide across the world. This article looks at carbon trading development so far and examines the key challenges ahead in China. These past experiences—whatever from international CDM practice, or SO₂ emission trading and a domestic voluntary carbon market—have paved the solid way to build the existing ETS pilots similar to European Union Emissions Trading System (EU ETS). The investigation into China’s ETS pilots discovered some important and urgent issues such as the capsetting and deepening energy market reform.     

“西为中用·顺势利导”——生态雨水机埠 与合流制特点的老旧城区海绵改造

以常德市柏子园汇水片区为例，运用水力模型工 具，探讨在老城区现有末端生态雨水机埠情形下，通过优化设 置低影响开发(LID)设施和管网改造工程，从源头解决机埠合 流制溢流(CSO)污染的效果和可行性。根据棚户区较多、绿 地率少、土壤渗透性差、项目实施难度大等情况，进行项目方 案布置和LID措施选择；根据现状管网特征，进行近远期管网 改造方案和源头截流措施选择。采用典型年降雨数据进行连续 模拟，分析评估在老旧城区增设源头控制设施和中途管网改造 对既定末端机埠溢流水量及溢流频次的控制效果，并通过情景 方案比选，得出在现有土地使用条件下的最优海绵改造方案， 以期为类似合流制特点的区域提供参考和借鉴。     

Arrow–Debreu equilibria for rank‐dependent utilities with heterogeneous probability weighting

We study Arrow–Debreu equilibria for a one‐period‐two‐date pure exchange economy with rank‐dependent utility agents having heterogeneous probability weighting and outcome utility functions. In particular, we allow the economy to have a mix of expected utility agents and rank‐dependent utility ones, with nonconvex probability weighting functions. The standard approach for convex economy equilibria fails due to the incompatibility with second‐order stochastic dominance. The representative agent approach devised in Xia and Zhou (2016) does not work either due to the heterogeneity of the weighting functions. We overcome these difficulties by considering the comonotone allocations, on which the rank‐dependent utilities become concave. Accordingly, we introduce the notion of comonotone Pareto optima, and derive their characterizing conditions. With the aid of the auxiliary problem of price equilibria with transfers, we provide a sufficient condition in terms of the model primitives under which an Arrow–Debreu equilibrium exists, along with the explicit expression of the state‐price density in equilibrium. This new, general sufficient condition distinguishes the paper from previous related studies with homogeneous and/or convex probability weightings.     

Context matters

Eliciting the level of risk aversion of experimental subjects is of crucial concern to experimenters. In the literature there are a variety of methods used for such elicitation; the concern of the experiment reported in this paper is to compare them. The methods we investigate are the following: Holt–Laury price lists; pairwise choices, the Becker–DeGroot–Marschak method; allocation questions. Clearly their relative efficiency in measuring risk aversion depends upon the numbers of questions asked; but the method itself may well influence the estimated risk-aversion. While it is impossible to determine a ‘best’ method (as the truth is unknown) we can look at the differences between the different methods. We carried out an experiment in four parts, corresponding to the four different methods, with 96 subjects. In analysing the data our methodology involves fitting preference functionals; we use four, Expected Utility and Rank-Dependent Expected Utility, each combined with either a CRRA or a CARA utility function. Our results show that the inferred level of risk aversion is more sensitive to the elicitation method than to the assumed-true preference functional. Experimenters should worry most about context.     

专题微课生物化学教学新模式的探索与实践

专题微课教学是基于一门学科或课程的某个重要专题设计开发的教学模式。课题组在生物化学的课程中设计了专题微课。生物化学的专题微课教学包括确立教学目标、教学方法、微课录制与编辑加工等环节，应注意建立全新的网络教学平台、互动式教学、抓好指导小组资料整理等教学策略，其成功需要教师有较高的综合素质和教学技能。实践证明，生物化学的专题微课教学取得了良好的教学效果，学生的成绩有了一定提高。     

任务体验模式在商务英语教学中的实证研究——基于语言经济学视角

基于语言经济学理论,分析探讨了任务体验模式在大学商务英语教学中的可行性和有效性。教学实验表明,以互联网和QQ通讯软件为支撑的大学商务英语任务体验模式不仅获得了学生的普遍认可,增强了学生参与活动的兴趣,而且有助于提高商务意识和学业成绩,同时还为校内商务英语实践提供了新途径。