Estimating Contaminant Dose for Intermittent Dermal Contact: Model Development, Testing, and Application

Assessments of aggregate exposure to pesticides and other surface contamination in residential environments are often driven by assumptions about dermal contacts. Accurately predicting cumulative doses from realistic skin contact scenarios requires characterization of exposure scenarios, skin surface loading and unloading rates, and contaminant movement through the epidermis. In this article we (1) develop and test a finite-difference model of contaminant transport through the epidermis; (2) develop archetypal exposure scenarios based on behavioral data to estimate characteristic loading and unloading rates; and (3) quantify 24-hour accumulation below the epidermis by applying a Monte Carlo simulation of these archetypal exposure scenarios. The numerical model, called Transient Transport through the epiDERMis (TTDERM), allows us to account for variable exposure times and time between exposures, temporal and spatial variations in skin and compound properties, and uncertainty in model parameters. Using TTDERM we investigate the use of a macro-activity parameter (cumulative contact time) for predicting daily (24-hour) integrated uptake of pesticides during complex exposure scenarios. For characteristic child behaviors and hand loading and unloading rates, we find that a power law represents the relationship between cumulative contact time and cumulative mass transport through the skin. With almost no loss of reliability, this simple relationship can be used in place of the more complex micro-activity simulations that require activity data on one- to five-minute intervals. The methods developed in this study can be used to guide dermal exposure model refinements and exposure measurement study design.     

Evaluating the Effectiveness of Risk-Reduction Strategies for Consumer Chemical Products

Communication about risks offers a voluntary approach to reducing exposure to pollutants. Its adequacy depends on its impact on behavior. Estimating those impacts first requires characterizing current activities and their associated risk levels, and then predicting the effectiveness of risk-reduction strategies. Characterizing the risks from chemical consumer products requires knowledge of both the physical and the behavioral processes that influence exposures. This article presents an integrated approach that combines consumer interviews, users' beliefs and behaviors, and quantitative exposure modeling. This model was demonstrated in the context of consumer exposure to a methylene chloride-based paint stripper, showing how it could be used to evaluate current levels of risk and predict the effectiveness of proposed voluntary risk-reduction strategies.     

Statistics Problems with Simple Numbers

This article concerns the construction of simple numerical illustrations of statistical techniques for use in introductory classes. Minimizing the amount of calculation facilitates checking, promotes reliability, is quicker, and reinforces the confidence of the student. Methods are described for generating (a) samples of size 3 upwards with integer-valued means and standard deviations, and (b) simple linear regressions with integer-valued intercepts and integer-valued or simple fractional slopes. Extensions to give exact pooled standard deviations in the two-sample problem and simple exact fractional correlation coefficients are also indicated. Further statistical procedures amenable to the same general approach are listed.     

Getting real: heuristics in sociological knowledge

Theory and Society - This article examines the connections among heuristics, the epistemological and ontological presuppositions that underlie theorizing, and substantive explanations in sociology....     

Motor Vehicles in China: The Impact of Demographic and Economic Changes

While China's transportation sector is relatively small compared to other nations—both in absolute terms and relative to the size of the population—the nation is currently experiencing one of the highest annual motorization growth rates in the world. This rapid growth has raised both excitement among business leaders over the potentially enormous market for automobiles and concern among environmentalists over their further impact on the global environment. This paper examines the influence of population growth, increased urbanization, and economic development on the rapid growth of motor vehicles in China, and considers their implications for future motor vehicle growth in the country.     

How do heat and flood risk drive residential green infrastructure implementation in Phoenix,Arizona?

Urban Ecosystems - Green infrastructure is an increasingly popular strategy to simultaneously address challenges associated with urbanization and global environmental change, including increased...     

The Service Brand as Relationships Builder

This article examines the appropriateness of the notion and application of relationship marketing in various contexts. Theoretical and conceptual similarities between the broad notions of ‘the brand’ and of relationship marketing as risk reducers, simplifiers of choice and guarantee of quality are uncovered. We put forward a notion of relationship marketing as a further step in the branding process, whereby whenever perceived risk and consumer involvement are high, relationship marketing acts as a supplementary tool enabling consumers to maintain cognitive consistency and psychological comfort. Experts' opinions regarding branding in a service context expanded on these concepts. Especially for more intangible offerings, such as financial services, the experts stressed the use of corporate brand identity as the basis of relationship building both inside and outside the organization and as a means to achieve differentiation and provide the focus for homogeneous and consistent service delivery. Finally, we suggest the concept of the service brand as a holistic process beginning with the relationship between the firm and its staff and coming alive during the interactions between staff and customers.     

Making Sense of the Census: Why Sampling Might Not Be so Simple

Population and Environment -