《算学启蒙》中的香料经济新探

《算学启蒙》中有关香料方面的算题,涉及元代市舶司的“双抽”和“单抽”、纸钞与铜银钱并用,以及各种香料的价格等问题。诚然,这些问题的解决,确实需要综合多种史籍来参互求证,但毋庸置疑的是《算学启蒙》起到了为其他史籍所无法取代的独特价值和作用。实际上,元代大德年间所发生的许多经济现象,都或多或少在《算学启蒙》一书中有所体现。随着学界对中国古代算书之史学价值的认识愈来愈明确,经济数学、数学社会学等新的交叉学科应运而生,我们不能仅仅囿于从纯数学的角度去解读《算学启蒙》,因为《算学启蒙》本身具有更重要的经济史和社会史的研究价值和意义。     

Can Shareholders Be at Rest after Adopting Clawback Provisions? Evidence from Stock Price Crash Risk

Using a propensity score matched sample and a difference‐in‐differences research design, we find that stock price crash risk increases after a firm voluntarily incorporates clawback provisions in executive officers' compensation contracts. This heightened crash risk is concentrated in adopters that increase upward real activities‐based earnings management and those that reduce the readability of 10‐K reports. Based on cross‐sectional analyses, we also find that the increased crash risk is more pronounced for adopters with high ex ante fraud risk, low‐ability managers, high CEO equity incentives, and low dedicated institutional ownership. Collectively, our results suggest that the clawback adoption per se does not curb managerial opportunism but rather induces managers to use alternative channels for concealing bad news, which may contribute to a greater stock price crash risk; and the increase in crash risk is more likely in cases where incentives are strong or monitoring is weak. Our results should be of interest to regulators and policymakers considering the effects of clawback adoption on the investing public.     

中国农药施用与农业经济增长脱钩状态：时空特征与影响因素

[目的]明确农药施用与农业经济增长关联状态及其影响因素,为实现"控药减害增收"的目标提供借鉴。[方法]基于2005—2015年数据利用脱钩理论和对数平均分解指数法分解进行分析。[结果]中国农业经济增长伴生大量农药施用,仅少数省域表现出农药施用和农业经济增长扩张绝对脱钩的理想状态,东北西北部分省域农业经济增长则以更大幅度的农药投入增长为代价。中西部地区劳动力规模和技术进步效应是推动农药施用与农业经济增长脱钩的因素;东部地区种植规模变化、劳动力规模和技术进步因素均是推动农药施用和农业经济增长脱钩的因素;东北地区仅劳动力规模效应成为推动脱钩的力量。[结论]推动农药施用与农业经济增长脱钩需要强化农业科技的创新与普及,完善农业生产过程中的技术支撑,推动农业病虫害监测预警,加大对环境友好型低污染农药和肥料的推广度;构建农户施药的多重约束机制,完善农业病虫灾害保险减少农户对生产过程的风险感知,发挥农业合作社对农户施药行为的规制作用,完善产品分级认证和安全准入制度;通过农地合理流转和农业机械化等方式集约利用农业生产资源;因地制宜推动农药施用与农业经济增长脱钩,结合区域资源优势和农业发展阶段有针对性地设计对策措施。     

Higher Intensity,Higher Profit? Empirical Evidence from Dairy Farming in New Zealand

Over the last two decades there have been significant and well‐documented changes in the nature and structure of New Zealand dairy production. One particular feature has been a marked shift in the ‘input intensity’ of dairy farming systems through increased use of supplementary feed. These changes have generated debate about the impact of dairy farm intensity on the performance of farm businesses and the competitiveness of the New Zealand dairy sector. Using a novel econometric approach, we assess statistically the impact of three types of dairy farming systems on milk production and financial performance, using farm business data provided by DairyBase^®. Our empirical results show that higher input systems perform significantly better physically than lower input systems, but not financially. The disaggregated analysis suggests that the average treatment effects differ by region and performance quantiles.     

内外融资条件、融资约束与企业绩效——来自京津冀地区企业调查的新证据*

基于独特的京津冀地区企业调查数据和克服内生性的结构方程模型，本文对融资约束的成因及影响进行了实证分析。分析结果表明，企业自身条件和外部市场环境均对融资约束有重要影响，且企业自身条件对融资约束的影响更强。总的融资约束指标对企业绩效的影响不显著。在区分融资约束的不同维度后，本文发现，融资可得性提高显著促进了企业绩效提升，融资频率增加却降低了企业绩效，而融资获得速度（等待时间）对企业绩效没有统计上的显著影响。进一步的分析表明，无论是正规融资渠道，还是非正规融资渠道，上述结论仍然成立。利用多种政策提高企业的管理水平，改善企业的自身条件，是缓解融资约束的最有效办法。     

提升城管执法公信力路径探究

城管执法公信力主要是指城管部门在对城市实施管理与执法过程中赢得或得到社会公众认可和信任的程度。然而,当前我国城管正处于深化改革转型期,城管执法公信力时常遭受公众质疑,甚至陷入了"塔西佗陷阱"。立足城管执法公信力的现状进行研究,从顶层设计、执法理念等层面对其弱化成因进行了透析,结合当前城管执法体制改革,提出了加强顶层设计、转变执法理念、建设职业伦理、完善协同治理和强化舆情管控等对策建议。     

Interpoint Distance Test of Homogeneity for Multivariate Mixture Models

Finite mixtures offer a rich class of distributions for modelling of a variety of random phenomena in numerous fields of study. Using the sample interpoint distances (IPDs), we propose the IPD‐test statistic for testing the hypothesis of homogeneity of mixture of multivariate power series distribution or multivariate normal distribution. We derive the distribution of the IPDs that are drawn from a finite mixture of the multivariate power series distribution and multivariate normal distribution. Based on the empirical distribution of the IPDs, we construct a bootstrap test of homogeneity for other multivariate finite mixture models. The IPD test is applied to mixture models for matrix‐valued distributions and a test of homogeneity for Wishart mixture is presented. Numerical comparisons show that IPD test has accurate type I errors and is more powerful in most multivariate cases than the expectation–maximization (EM) test and modified likelihood ratio test.     

Volatility forecasting: long memory,regime switching and heteroscedasticity

In this article, we account for the first time for long memory, regime switching and the conditional time-varying volatility of volatility (heteroscedasticity) to model and forecast market volatility using the heterogeneous autoregressive model of realized volatility (HAR-RV) and its extensions. We present several interesting and notable findings. First, existing models exhibit significant nonlinearity and clustering, which provide empirical evidence on the benefit of introducing regime switching and heteroscedasticity. Second, out-of-sample results indicate that combining regime switching and heteroscedasticity can substantially improve predictive power from a statistical viewpoint. More specifically, our proposed models generally exhibit higher forecasting accuracy. Third, these results are widely consistent across a variety of robustness tests such as different forecasting windows, forecasting models, realized measures, and stock markets. Consequently, this study sheds new light on forecasting future volatility.     

Operating cash flow asymmetric timeliness in Australia

Operating cash flow (CFO) asymmetric timeliness occurs when CFO reflects bad news more quickly than good news. We examine the presence and determinants of CFO asymmetric timeliness in Australia, where substantial differences in reporting requirements of cash flow components, in characteristics of listed companies and in the degree of conservative financial reporting produce contrasting findings to those in the United States. We find supportive evidence for the novel ‘sticky cost behaviour’ explanation and also the product-pricing strategy, but not the life cycle hypothesis. These findings are useful for investors and analysts concerned with forecasting the future values of companies.     

辣木树不同部位γ-氨基丁酸的HPLC分析

用高效液相色谱法检测了辣木树不同部位γ-氨基丁酸的含量,结果表明:每100 g样品中,辣木果实、叶、果皮、花、根、籽及茎中的GABA含量分别为378.39、275.64、194.15、96.42、69.14、27.32 mg与0.00 mg。由此可见,辣木树中富含GABA,且幼嫩部位含量较高,本研究可为辣木产品的质量评价、开发利用以及辣木树中GABA的合成部位与运输情况研究提供理论参考。