工作用玻璃液体温度计检定注意事项

在温度计的检定过程中,温度计插入恒温槽中不垂直、读数不准确等因素都将给检定结果带来较大的误差,从6个方面讲述了检定过程中需注意的事项,并提出了相应的解决方法,从而减小了温度计的测量误差,提高了测量准确度。     

罗茨鼓风机在氢气输送中的应用

本文介绍了L系列罗茨鼓风机在氢气输送过程中替代液环泵的优势与特点。     

格列苯脲有关物质检查中色谱柱的选择

高效液相色谱法作为含量测定和有关杂质检查的方法被越来越多地应用于各国药品标准中,色谱柱是高效液相色谱法的关键,但由于色谱柱种类繁多以及选择性的差异,导致药典在执行过程中很难保证检查方法的重现性,因此选择合适的色谱柱成为色谱分析的关键。以降糖药格列苯脲有关物质检查中色谱柱的选择为例,参照欧洲药典(EP7.0),对给出的5种色谱柱分别按照不同的分类方法进行分类,对5种色谱柱有关物质检查系统的适用性分别进行测试。根据测试结果得出的结论,分析比较了不同色谱柱分类方法对色谱柱选择所起的作用。分析结果表明,结合不同的色谱柱分类方法对色谱柱进行选择,可以选出适用的色谱柱。     

反相高效液相色谱法快速分析紫脲酸

为了给咖啡因生产中的亚硝化反应、还原工艺提供准确的中间体检测数据,寻找紫脲酸含量快速分析方法,利用反相高效液相色谱法,通过进行紫脲酸样品波长选择实验、系统适用性实验、定量摸索实验、精密度实验、线性实验,确定了检测波长和紫脲酸样品质量浓度与样品峰面积之间的线性关系。在15.80~188.60mg/L范围内,紫脲酸样品质量浓度与样品峰面积之间的线性方程为y=71.785x,相关系数R2=0.999 8,表明紫脲酸样品质量浓度与样品峰面积之间具有良好的线性关系。使用反相高效液相色谱法能准确、快速检测紫脲酸样品含量,及时对还原反应进行过程监控。     

液态奶加工中的“过度加热”倾向分析

近年来,我国牛奶加工产业有了迅猛发展,但也存在一些问题,如液态奶加工中的“过度加热”问题。本文通过对过度加热液态奶的判定模式进行探究,分析“过度加热”的危害,总结在液态奶加工中出现“过度加热”的原因,以促进液态奶合理加工,推动我国乳业健康发展。     

On the predictability of the distribution of excess returns in currency markets

This paper investigates the predictability of foreign exchange (FX) volatility and liquidity risk factors on returns to the carry trade, an investment strategy that borrows in currencies with low interest rates and invests in currencies with high interest rates. Previous studies have suggested that this predictability could have been spuriously accounted for due to the persistence of the predictors. The analysis uses a predictive quantile regression model developed by Lee (2016) that allows for persistent predictors. We find that predictability changes remarkably across the entire distribution of currency excess returns. Predictability weakens substantially in the left tail once persistence is accounted for, implying a moderate negative predictive relation between FX volatility risk and carry trade returns. By contrast, it becomes stronger in the right tail. Furthermore, we provide evidence that FX volatility risk still dominates liquidity risk after controlling for persistence. These findings suggest that the persistence of the predictors needs to be taken into account when one measures predictability in currency markets. Finally, out-of-sample forecast performance is also presented.     

Carry

We apply the concept of carry, which has been studied almost exclusively in currency markets, to any asset. A security’s expected return is decomposed into its “carry,” an ex-ante and model-free characteristic, and its expected price appreciation. Carry predicts returns cross-sectionally and in time series for a host of different asset classes, including global equities, global bonds, commodities, US Treasuries, credit, and options. Carry is not explained by known predictors of returns from these asset classes, and it captures many of these predictors, providing a unifying framework for return predictability. We reject a generalized version of Uncovered Interest Parity and the Expectations Hypothesis in favor of models with varying risk premia, in which carry strategies are commonly exposed to global recession, liquidity, and volatility risks, though none fully explains carry’s premium.     

An examination of the effects of 2014 concealed weapons law in Illinois on property crimes in Chicago

The purpose of the present study is to determine the effects of ‘may issue’ Concealed Carry Weapons (CCW) law implemented in early 2014 in Chicago. Based on the daily community-level crime data from January 2006 to December 2015, using zero-inflated negative binomial difference-in-difference specification with Philadelphia as the control group, the property crimes in Chicago declined after the implementation of ‘may issue’ CCW law. The findings are robust to alternate treatment windows and to a placebo test using time windows before implementation of the law.     

对国内外砂土地震液化评价介绍及比较

本文通过应用国内外不同的勘察规范对同一个工程场地的地震液化等级划分的计算及评价介绍,得出了一个采用不同规范,可取得比较一致的地震砂土液化等级的结论。