《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。     

Measuring Farm and Market Level Economic Impacts of Improved Maize Production Technologies in Ethiopia: Evidence from Panel Data

While it is often recognised that agricultural technology adoption decisions are intertwined and best characterised by multivariate models, typical approaches to examining adoption and impacts of agricultural technology have focused on single technology adoption choice and ignored interdependence among technologies. We examine farm‐ and market‐level impacts of multiple technology adoption choices using comprehensive household survey data collected in 2010/11 and 2012/13 in Ethiopia. Economic surplus analysis combined with panel data switching endogenous regression models are used to compute the supply shift parameter (K‐shift parameter), while at the same time controlling for the endogeneity inherent in agricultural technology adoption among farmers. We find that our improved technology set choices have significant impacts on farm‐level maize yield and maize production costs, where the greatest effect appears to be generated when various technologies are combined. The change in maize yield and production costs results in an average 26.4% cost reduction per kilogram of maize output (the K‐shift parameter). This increases the producer and consumer surpluses by US$ 140 and US$ 105 million per annum, respectively. These changes in economic surplus help to reduce the number of poor people by an estimated 788 thousand per year. We conclude that deliberate extension efforts and other policies that encourage integration of technologies are important for maize technologies to yield their full potential at both farm and market levels.     

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.     

Past price ‘memory’ in the housing market: testing the performance of different spatio-temporal specifications

Recent methodological developments provide a way to incorporate the temporal dimension when accounting for spatial effects in hedonic pricing. Weight matrices should decompose the spatial effects into two distinct components: bidirectional contemporaneous spatial connections; and unidirectional spatio-temporal effects from past transactions. Our iterative estimation approach explicitly analyses the role of time in price determination. The results show that both spatio-temporal components should be included in model specification; past transaction information stops contributing to price determination after eight months; and limited temporal friction is exhibited within this period. These findings highlight the decidedly non-linear temporal patterns of such information effects.     

去库存及建筑总量控制政策对三四线城市能源消耗的影响效应研究

近十年来房地产开发迅猛,在满足人们居住需求的同时也伴随着大量泡沫的涌现。中央提出的供给侧改革、去库存和能效提升给建筑部门指明了发展方向,有效地实施供给侧改革是建筑部门一项重要工作。拟通过开展去库存及建筑总量控制对三四线城市能源消耗的影响研究,为建筑部门的供给侧改革提供建议和参考。站在建筑部门宏观视角,通过文献调查,分析总结了建筑终端能耗影响因素及其影响效应,梳理了中国建筑总量、库存量及建筑领域能源消耗量总体情况,论述了三四线城市去库存、进行建筑总量控制的重要性;在此基础上,根据分析结果、三四线城市特点及数据可获得性,选定自变量和因变量及量化指标,运用岭回归方法,以6个城市的数据为例进行三四线城市建筑总量控制、去库存政策对城市能耗影响效果的定量分析;最后基于彼此间关系及研究过程中发现的问题对建筑部门的供给侧改革工作提出建议。     

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.     

Effects of investor tax heterogeneity on stock prices and trading behaviour around the ex-dividend day: the case of Australia

Using a sample of Australian stocks during the 1996–2014 period, this study examines how tax heterogeneity between domestic and foreign investors affects trading behaviour and stock prices around the ex-dividend day. Domestic investors prefer dividends and tend to buy stocks cum-dividend and sell them ex-dividend whereas foreign investors tend to trade in the opposite direction. Abnormal trading turnover increases with tax heterogeneity. Moreover, stocks with a larger domestic investor base are associated with a higher price drop-off ratio on the ex-dividend day and higher market value of franking credits. Overall, our findings support the dynamic dividend clientele hypothesis.     

刺芪参胶囊的制备工艺研究

目的:探索刺芪参胶囊的制备工艺。方法:采用正交实验,以总皂苷质量为指标,优化提取工艺;采用单因素实验优化制剂工艺。结果:在最佳提取工艺条件下,刺芪参胶囊提取物中的总皂苷含量为12.19 mg·g-1;以糊精作为填充剂、硬脂酸镁为助流剂、95%乙醇为黏合剂制备胶囊剂。结论:刺芪参胶囊的制备工艺稳定可行。     

淮扬饮食文化的特点及发展路径探究

淮扬历史文化悠久,塑造了独特的饮食文化,其"精""雅""养"的饮食文化特质,成为中国饮食文化中的独特元素.在新的时代环境之下实现新的发展,这是淮扬饮食文化发展的内在需求.本文立足淮扬饮食文化特点,分析了其发展中面临的问题,并在此基础之上,从推动饮食文化创新、推动饮食产业发展、打造市场品牌影响力、实施"饮食+"措施等方面,阐述了淮扬饮食文化发展的路径.     

苹果种植适度规模经营研究*——以陕西省白水县为例

［目的］分析苹果种植户经济效益的影响因素，研究适合苹果种植的农地规模，提高白水县果农苹果种植的经济效益，探索苹果产业可持续发展经营模式，丰富以果蔬为主的集约型经济作物适度规模经营研究范围。［方法］采用实地调研法，对陕西省白水县230户苹果种植户进行问卷调查，从收益最大化角度，运用柯布道格拉斯生产函数对苹果生产的投入产出进行经济分析，构建收益最大化模型，测算白水县苹果种植的最适规模，分析苹果产量的影响因素，探讨劳动力投入、资本投入、有效面积和果农参加技术培训对苹果产出的影响和贡献程度，并用钱克明等对农地的适度经营规模定义进行结果验证，最后提出合理的政策建议。［结果］经过分析，在同等技术条件下，劳动力投入、资本投入、有效种植面积、果农参加技术培训的次数对苹果的产出具有显著影响。以农户收益最大化模型测算的劳均经营规模面积在0363~0447hm2（544~670亩）的可视为适度规模，根据钱克明等的适度经营规模目标值的计算，其函数解为550，在适度规模范围之内。即户均农地适度经营规模0751~0966hm2（1127~1449亩）。目前白水县苹果生产处于规模报酬递减阶段，农资市场环境和劳动力投入方面仍然存在短板。［结论］建议扩大白水县户均苹果种植面积，提升土地经营效益，从而增加果农收入，支持农业新型经营主体发展，创新发展模式； 建立新型职业农民培育体系，促进苹果种植户剩余劳动力转移，提高农民非农收入； 从法律上规范农村地区农资市场环境； 规范农户绿色生产经营行为，提高化肥的使用效率和开发新的高效肥料； 政府引导农地的适度规模集中，整合资源进行规模化、现代化的经营。