Advances on a Decision Analytic Approach to Exposure-Based Chemical Prioritization

The volume and variety of manufactured chemicals is increasing, although little is known about the risks associated with the frequency and extent of human exposure to most chemicals. The EPA and the recent signing of the Lautenberg Act have both signaled the need for high-throughput methods to characterize and screen chemicals based on exposure potential, such that more comprehensive toxicity research can be informed. Prior work of Mitchell et al. using multicriteria decision analysis tools to prioritize chemicals for further research is enhanced here, resulting in a high-level chemical prioritization tool for risk-based screening. Reliable exposure information is a key gap in currently available engineering analytics to support predictive environmental and health risk assessments. An elicitation with 32 experts informed relative prioritization of risks from chemical properties and human use factors, and the values for each chemical associated with each metric were approximated with data from EPA's CP_CAT database. Three different versions of the model were evaluated using distinct weight profiles, resulting in three different ranked chemical prioritizations with only a small degree of variation across weight profiles. Future work will aim to include greater input from human factors experts and better define qualitative metrics.     

Approximation of transition densities of stochastic differential equations by saddlepoint methods applied to small-time Ito–Taylor sample-path expansions

Likelihood-based inference for parameters of stochastic differential equation (SDE) models is challenging because for most SDEs the transition density is unknown. We propose a method for estimating the transition density that involves expanding the sample path as an Ito–Taylor series, calculating the moment generating function of the retained terms in the Ito–Taylor expansion, then employing a saddlepoint approximation. We perform a numerical comparison with two other methods similarly based on small-time expansions and discuss the pros and cons of our new method relative to other approaches.     

Designing an HIV counseling and testing program for bathhouses: the Seattle experience with strategies to improve acceptability

Bathhouses are important venues for providing HIV counseling and testing to high-risk men who have sex with men (MSM), yet relatively few bathhouses routinely provide this service, and few data are available to guide program design. We examine numerous logistic considerations that had been identified in the HIV Alternative Testing Strategies study and that influenced the initiation, effectiveness, and maintenance of HIV testing programs in bathhouses for MSM. Key programmatic considerations in the design of a bathhouse HIV counseling and testing program included building alliances with community agencies, hiring and training staff, developing techniques for offering testing, and providing options for counseling, testing, and disclosure of results. The design included ways to provide client support and follow-up for partner notification and treatment counseling and to maintain relationships with bathhouse management for support of prevention activities. Early detection of HIV infection and HIV prevention can be achieved for some high-risk MSM through an accessible and acceptable HIV counseling and testing program in bathhouses. Keys to success include establishing community prevention collaborations between bathhouse personnel and testing agencies, ensuring that testing staff are supported in their work, and offering anonymous rapid HIV testing. Use of FDA approved, new rapid tests that do not require venipuncture, centrifugation, or laboratory oversight will further decrease barriers to testing and facilitate implementation of bathhouse testing programs in other communities.     

Spline interpolation for demographic variables: The monotonicity problem

In demography, it is often necessary to obtain a monotonic interpolation of data. A solution to this problem is available using the Hyman filter for cubic splines. However, this does not seem to be well known amongst demographers, and no implementation of the procedure is readily available. We remedy these problems by outlining the relevant ideas here, and providing a function for the R language.     

ESTIMATION OF A PROPORTION USING SEVERAL INDEPENDENT SAMPLES OF BINOMIAL MIXTURES

This paper considers a sequence of independent counts, with each count arising from a mixture of binomial distributions; the mixing distribution is fixed but the number of trials varies from count to count. In this common situation, an estimate of the underlying mean binomial proportion is needed. Two estimators are in general use: the arithmetic average and a weighted average of the observed proportions. Variances of the two estimators are compared and used to decide which estimator is preferred in a given context. The relative merits depend on the distribution of the proportions and the numbers of trials used.     

Attribution Style and Public Policy Attitudes Toward Gay Rights*

Objective. This study examines the influence of beliefs about the cause of homo‐sexuality on public policy attitudes concerning gay rights. Methods. Using data from the 1995 Oklahoma City Survey, we examine how beliefs about homosexuality as either a lifestyle choice or biological predisposition affect levels of support for gay rights. Results. Consistent with current debates over gay rights, our study reveals a strong positive association between biological attributions of homosexuality and support for gay rights. Opposition to gay rights is most pronounced among political conservatives, fundamentalist Protestants, persons with little or no favorable contact with gays, individuals who embrace negative stereotypes about gays, and persons with high scores on an index of homophobia. Conclusions. Etiological beliefs about homosexuality have a strong influence on public policy attitudes toward gay rights.     

Testing for efficiency and non-linearity in market and natural time series

Time series in traded markets such as currencies and securities involve supply/demand interaction, so they might be expected to contain distinctive and identifiable structures in comparison with data based on natural phenomena such as river flows or sunspots. This paper tests this proposition using standard econometric tests including variance ratios, modified rescaled range (R/S) ratios and BDS statistics together with non-linear prediction models. Four time series of each type (market or natural) are subject to a battery of tests for random walk and non-linear dependence. Surprisingly, the tests provide no reliable discrimination between the two types of series or reveal any embedded specification differences.     

保护区管理存在的问题与根源

要想实现保护区的有效管理,必须明确保护区管理存在的问题与根源.文章将保护区管理存在的各种具体问题抽象分类形成问题树,发现这些问题可以归结为权属、管理和政策三方面因素.这三大因素正是保护区管理的"症结所在",这一结论可为保护区管理政策与措施的制定提供参考意见.此外,保护区与周边社区的矛盾冲突问题,也是该文分析研究的一个重点内容.