Variability in Physical Constant Parameter Values from Standard Data Sources and the Implication of This Variability for Risk Analysis

Physical property values are used in environmental risk assessments to estimate media and risk-based concentrations. However, considerable variability has recently been reported with such values. To evaluate potential variability in physical parameter values supporting a variety of regulatory programs, eight data sources were chosen for evaluation, and chemicals appearing in at least four sources were selected. There were 755 chemicals chosen. In addition, chemicals in seven environmentally important subgroups were also identified for evaluation. Nine parameters were selected for analysis-molecular weight (MolWt), melting point (MeltPt), boiling point (BoilPt), vapor pressure (VP), water solubility (AqSOL), Henry's law constant (HLC), octanol-water partition coefficient (Kow), and diffusion coefficients in air (Dair) and water (Dwater). Results show that while 71% of constituents had equal MolWts across data sources, <3% of the constituents had equivalent parameter values across data sources for AqSOL, VP, or HLC. Considerable dissimilarity between certain sources was also observed. Furthermore, measures of dispersion showed considerable variation in data sets for Kow, VP, AqSOL, and HLC compared to measures for MolWt, MeltPt, BoilPt, or Dwater. The magnitude of the observed variability was also noteworthy. For example, the 95th percentile ratio of maximum/minimum parameter values ranged from 1.0 for MolWt to well over 1.0E + 06 for VP, and HLC. Risk and exposure metrics also varied by similar magnitudes. Results with environmentally important subgroups were similar. These results show that there is considerable variability in physical parameter values from standard sources, and that the observed variability could affect potential risk estimates and perhaps risk management decisions.     

Development and Consideration of Global Policies for Managing the Future Risks of Poliovirus Outbreaks: Insights and Lessons Learned Through Modeling

The success of the Global Polio Eradication Initiative promises to bring large benefits, including sustained improvements in quality of life (i.e., cases of paralytic disease and deaths avoided) and costs saved from cessation of vaccination. Obtaining and maintaining these benefits requires that policymakers manage the transition from the current massive use of oral poliovirus vaccine (OPV) to a world without OPV and free of the risks of potential future reintroductions of live polioviruses. This article describes the analytical journey that began in 2001 with a retrospective case study on polio risk management and led to development of dynamic integrated risk, economic, and decision analysis tools to inform global policies for managing the risks of polio. This analytical journey has provided several key insights and lessons learned that will be useful to future analysts involved in similar complex decision-making processes.     

The Formation and Development of New Zealand English: Interaction of Gender-Related Variation and Linguistic Change

This research assesses the relative roles played by men and women in the development of New Zealand English. Real-time evidence on the development of NZ English over the past fifty years is provided by comparison of speakers recorded in 1948 and their present day descendants recorded recently. Elements of two vowel shifts are studied, and particular attention is paid to the vowel variables in words such as MOUTH, TRAP and DRESS. Results indicate that women lead in changes which are new and dynamic, but lag behind men in the use of variables representing older changes. While these results mirror patterns of gender-related variation observed in other contexts, explanations in terms of prestige which are often assumed to account for this pattern of variation are found to be inadequate in the New Zealand case. Rather, a hypothesis in terms of dialect contact, and specifically women's preferred discourse strategies in contact situations, is used to explain the process and progress of linguistic change in NZ English.     

《老残游记》清官批判思想之探源

刘鹗自称 :历来小说“有揭清官之恶者 ,自《老残游记》始”。其实 ,《老残游记》对清宫的批判 ,一源于司马迁《史记》以及历代史书中的《酷吏传》 ,一源于李贽评点杨慎《党籍碑》之文章。李贽“君子而误国”、“清官之害大”的思想 ,以及对程朱理学的非议 ,对《老残游记》影响最为显著。     

李商隐诗作的变异心理分析

李商隐诗作的隐义性历来多难索解。从创作心态角度进行研究 ,前人多侧重于常态心理而未涉及其变异心理。义山诗的变异心理表现为 :担心美好事物易逝的“强迫性感伤”情绪 ,压抑对婚姻的怨恨并将其转化为关爱的“反向形式” ,时有压抑性兴奋并将其雅化诗化为“性诙谐”诗作 ,只有在具禁止色彩的恋爱对象时才燃起“犯禁”的激情并在其影响下形成“忆内”诗与“恋情诗”风格的不同。     

BL Lac天体的含义（Ⅰ）

本文分析了９２个射电选ＢＬＬａｃ天体（ＲＢＬｓ）样本发现具有高红移的样本对Ｈｕｂｂｌｅ关系的偏离很大，同时，样本的高偏振与大幅度的光变有关。     

DO NOT WEIGHT FOR HETEROSCEDASTICITY IN NONPARAMETRIC REGRESSION

The potential role of weighting in kernel regression is examined. The concept that weighting has something to do with heteroscedastic errors is shown to be false. However, weighting does affect bias, and ways in which this might be exploited are indicated.     

Direct Inference, Probability, and a Conceptual Gulf in Risk Communication

Differences in the conceptual frameworks of scientists and nonscientists may create barriers to risk communication. This article examines two such conceptual problems. First, the logic of "direct inference" from group statistics to probabilities about specific individuals suggests that individuals might be acting rationally in refusing to apply to themselves the conclusions of regulatory risk assessments. Second, while regulators and risk assessment scientists often use an "objectivist" or "relative frequency" interpretation of probability statements, members of the public are more likely to adopt a "subjectivist" or "degree of confidence" interpretation when estimating their personal risks, and either misunderstand or significantly discount the relevance of risk assessment conclusions. If these analyses of inference and probability are correct, there may be a conceptual gulf at the center of risk communication that cannot be bridged by additional data about the magnitude of group risk. Suggestions are made for empirical studies that might help regulators deal with this conceptual gulf.     

Propagation of Uncertainty in Risk Assessments: The Need to Distinguish Between Uncertainty Due to Lack of Knowledge and Uncertainty Due to Variability

In quantitative uncertainty analysis, it is essential to define rigorously the endpoint or target of the assessment. Two distinctly different approaches using Monte Carlo methods are discussed: (1) the end point is a fixed but unknown value (e.g., the maximally exposed individual, the average individual, or a specific individual) or (2) the end point is an unknown distribution of values (e.g., the variability of exposures among unspecified individuals in the population). In the first case, values are sampled at random from distributions representing various "degrees of belief" about the unknown "fixed" values of the parameters to produce a distribution of model results. The distribution of model results represents a subjective confidence statement about the true but unknown assessment end point. The important input parameters are those that contribute most to the spread in the distribution of the model results. In the second case, Monte Carlo calculations are performed in two dimensions producing numerous alternative representations of the true but unknown distribution. These alternative distributions permit subject confidence statements to be made from two perspectives: (1) for the individual exposure occurring at a specified fractile of the distribution or (2) for the fractile of the distribution associated with a specified level of individual exposure. The relative importance of input parameters will depend on the fractile or exposure level of interest. The quantification of uncertainty for the simulation of a true but unknown distribution of values represents the state-of-the-art in assessment modeling.     

随机Fuzzy子集理论初步

本文认为现行的Fuzzy子集理论有缺点,不能真实、准确地描述现实世界,因此有必要进行改进。我们将用随机Fuzzy子集理论中的随机隶属过程代替Fuzzy子集理论中的隶属函数,将客观世界中的确定性现象、随机现象和模糊现象结合起来进行研究。