Expert Views on Their Role as Policy Advisor: Pilot Study for the Cases of Electromagnetic Fields,Particulate Matter,and Antimicrobial Resistance

This perspective presents empirical data to demonstrate the existence of different expert views on scientific policy advice on complex environmental health issues. These views are partly research‐field specific. According to scientific literature, experts differ in the way they provide policy advice on complex issues such as electromagnetic fields (EMF), particulate matter (PM), and antimicrobial resistance (AMR). Where some experts feel their primary task is to carry out fundamental research, others actively engage in the policy dialogue. Although the literature provides ideas about expert roles, there exists little empirical underpinning. Our aim is to gather empirical evidence about expert roles. The results of an international study indicated that experts on EMF, PM, and AMR differ in the way they view their role in the policy dialogue. For example, experts differed in their views on the need for precaution and their motivation to initiate stakeholder cooperation. Besides, most experts thought that their views on the risks of EMF/PM/AMR did not differ from those of colleagues. Great dissensus was found in views on the best ways of managing risks and uncertainties. In conclusion, the theoretical ideal–typical roles from the literature can be identified to a certain extent.     

电生理诊断中实时数字滤波器的设计与实现

根据视觉电生理信号的特点，采用计算机软件方法实现了一种消除人体５０Ｈｚ工频干扰的实时带阻滤波器．     

三角形取样鉴相数字合成器锁相环中的混沌

研究三角形取样鉴相数字合成器锁相环中的混沌现象。其方法是先对三角形取样鉴相数字合成器锁相环系统作离散化处理,得到相应的离散化系统模型;系统中的环路滤波器采用RC积分滤波器,鉴相器采用三角形鉴相特性;通过验证离散化系统相应的低维系统存在快返反射点,证明了当系统方程满足一定条件时,原系统有混沌输出。最后导出了混沌与系统参数间的关系式。     

保图像细节的DWAWMTMF算法

提出双窗自适应加权中值-截尾均值滤波算法。根据信号结构特征设计出自适应计算滤波参数的方法,该方法在抑制加性混合噪声和保图像细节等方面有优良的性能,综合性能优于3LH+、DWMTMF、ACWM。     

试论英语教学中的“情感过滤”

“情感过滤”和“输入”是影响外语习得的两大重要因素。该文首先论述了“情感过滤”对外语习得和学习的作用机制 ,然后分析了引起“情感过滤”的四大情感因素 ,并提出怎样减少或消除学习者的“情感过滤”来提高英语教学质量的方法。     

Quantifying the Economic Impact of Hydraulic Fracturing Proppant Selection in Light of Occupational Exposure Risk and Functional Requirements

Selection of an effective and economic proppant material for hydraulic fracturing is an important design choice to optimize the production of oil and natural gas. Proppants are made of silica (quartz sand), alumina, resin-coated silica, ceramics, and others. These materials can be toxic to varying degrees and lead to health problems in the employees handling them primarily due to inhalation exposure. Proppants are selected based on grain size, shape, strength, and cost. Current use is dominated by crystalline silica—the proppant that also has the greatest hazard as an inhalation toxin. Existing research describes the effect of silica on human health, but little research has been done to determine the risk-reduction and social-cost-effectiveness associated with using alternative proppants in light of the health risks. This study quantifies the relative risks or benefits to human health by the use of these proppants through an economic analysis considering the health-related economic impact and its technical attributes. Results show that the use of each ton of silica proppant results in $123 of external costs from fatalities and nonfatal illness arising due to exposure to silica for a crew handing 60,000 tons of proppants. If these health-related externalities were incorporated into the cost, silica proppant could be economically replaced by less harmful, more expensive alternatives for hydraulic fracturing crews handling less than 60,000 tons of proppant each year.     

用HD复合溶剂改善催化柴油安定性的研究

针对催化柴油安定性差问题,对其不安定组分和改善其安定性的方法进行了研究,结合炼油厂的生产实际,利用复合溶剂对催化柴油萃取精制的生产工艺进行了开发和试验。用HD复合溶剂对催化裂化柴油进行精制后,精制油的催速储存安定性沉渣和颜色均达到了优级轻柴油的标准,在剂油比为1:500—50:500,精制油的收率为99%以上,老化沉渣<2.5·10-2mg/ml,老化色号不大于3.5,实际胶质的降低率达到了60.1%,氧化沉渣降低77.6%,脱硫率19.8%,脱氮率20.3%。     

Prediction and forecasting in linear models with measurement error

We consider measurement error models within the time series unobserved component framework. A variable of interest is observed with some measurement error and modelled as an unobserved component. The forecast and the prediction of this variable given the observed values is given by the Kalman filter and smoother along with their conditional variances. By expressing the forecasts and predictions as weighted averages of the observed values, we investigate the effect of estimation error in the measurement and observation noise variances. We also develop corrected standard errors for prediction and forecasting accounting for the fact that the measurement and observation error variances are estimated by the same sample that is used for forecasting and prediction purposes. We apply the theory to the Yellowstone grizzly bears and US index of production datasets.     

Bayesian Analysis of an Unobserved-Component Time Series Model of GDP With Markov-Switching and Time-Varying Growths

We propose an unobserved-component time series model of gross domestic product that includes Markov switching as an unobserved component. In addition to a trend component, the model has two time-varying drift components. One drift represents the expected rate of growth during recession; the other drift represents the expected rate during expansion. Estimates indicate a substantial decline in the latter annual rate for the United States from 6.4% in 1950 to 3.6% by 1990. We have employed weak priors based on prewar data. The estimation makes use of the Gibbs sampler and the Metropolis algorithm.     

Estimation of an Asymmetric Stochastic Volatility Model for Asset Returns

A stochastic volatility model may be estimated by a quasi-maximum likelihood procedure by transforming to a linear state-space form. The method is extended to handle correlation between the two disturbances in the model and applied to data on stock returns