A critique of figure placement procedures in studies of crowding

Although often used, Desor's figure-placement procedure makes an assumption that has not been tested. Two studies briefly reported indicate that the assumption that a constant criterion of crowdedness is being applied to different conditions is not always true. Several implications for simulation techniques and for general research strategies are discussed.Michael Stevens assisted in conducting the research.     

A COMPARATIVE PERSPECTIVE ON RACIAL RESIDENTIAL SEGREGATION:

This article takes a first step to compare the residential segregation of blacks and Asians from whites in American and Canadian cities. The analysis is based on census data from 404 American and 41 Canadian cities. African Americans in the United States experience a higher level of residential segregation than Asians in U.S. cities. On the other hand, blacks in Canada experience the same low level of segregation as Asians. To explain the different experiences of blacks in the United States and Canada, a multivariate model is proposed and tested. The results reveal several patterns. First, African Americans are consistently obstructed much more than Asian Americans by their proportion in the city. In contrast blacks in Canada are not. Second, the residential segregation patterns of African Americans are affected strongly by the labor market and strucutral changes of the economy in the city. However, the structural change of the economy in the city has a very weak effect on the level of residential segregation of Asian Americans, black Canadians, and Asian Canadians.     

Electric-Utility Resource Planning and Decision-Making: The Importance of Uncertainty

Uncertainty is a critical factor that pervades all aspects of electric-utility planning. Uncertainties about future load growth, about the continued performance of existing supply and demand resources, and about the costs, construction times, and operations of new resources greatly complicate utility resource acquisition. This paper discusses the factors that lead to uncertainty, reviews the methods that utilities use in planning and in acquiring resources, and suggests future research to help deal with these uncertainties. This review is based on assessments of the long-term resource plans prepared by 10 utilities and one Public Service Commission, telephone interviews with staff at these 11 organizations and with staff at three consulting firms, and reviews of many other related publications.     

A Trichloroethylene Risk Assessment Using a Monte Carlo Analysis of Parameter Uncertainty in Conjunction with Physiologically-Based Pharmacokinetic Modeling

A Monte Carlo simulation is incorporated into a risk assessment for trichloroethylene (TCE) using physiologically-based pharmacokinetic (PBPK) modeling coupled with the linearized multistage model to derive human carcinogenic risk extrapolations. The Monte Carlo technique incorporates physiological parameter variability to produce a statistically derived range of risk estimates which quantifies specific uncertainties associated with PBPK risk assessment approaches. Both inhalation and ingestion exposure routes are addressed. Simulated exposure scenarios were consistent with those used by the Environmental Protection Agency (EPA) in their TCE risk assessment. Mean values of physiological parameters were gathered from the literature for both mice (carcinogenic bioassay subjects) and for humans. Realistic physiological value distributions were assumed using existing data on variability. Mouse cancer bioassay data were correlated to total TCE metabolized and area-under-the-curve (blood concentration) trichloroacetic acid (TCA) as determined by a mouse PBPK model. These internal dose metrics were used in a linearized multistage model analysis to determine dose metric values corresponding to 10^-6 lifetime excess cancer risk. Using a human PBPK model, these metabolized doses were then extrapolated to equivalent human exposures (inhalation and ingestion). The Monte Carlo iterations with varying mouse and human physiological parameters produced a range of human exposure concentrations producing a 10^-6 risk.     

THE CREATION OF POLITICAL SOLIDARITY IN SOCIAL MOVEMENT ORGANIZATIONS*

This article examines the debate within resource mobilization theory concerning the motivation of participants in social movement organizations. Conclusions based on a case study of a Chicago community organization emphasize the importance of political solidarity in movement groups. An argument is made for a stage model of mobilization in which different types of incentives dominate motivation at different levels of involvement in the organization.     

A preliminary evaluation of the effects of a science education curriculum on changes in knowledge of drugs in youth

Drug and alcohol use among youth remains at pervasively high levels, but students are receiving less school-based prevention. Infusing health information into core curricula may be a valuable prevention approach. Therefore, behavior change theory was used to develop a science education curriculum on drugs for fourth- and fifth-grade students, which was then evaluated using a pretest/posttest quasi-experimental design. Exposure to the curriculum was associated with a change in knowledge; other characteristics like grade level also played a role. More positive attitudes toward science at pretest predicted greater knowledge change, and students who knew less at the start showed a greater change in knowledge. Results of this evaluation may support the efficacy of the curriculum and the utility of combining behavior change theory with educational approaches.     

Options to liberalize Social Security disabled widow(er)s benefits

Each month, 200,000 widows and 6,000 widowers receive Social Security disabled widow(er)s benefits, each benefit averaging about $550. Among the most economically at-risk Social Security beneficiaries, their benefits are permanently reduced. This paper reviews the legislative history of the disabled widow(er)s benefit, identifying key decisions that gave shape to this benefit. Social Security program data and six years of Current Population Survey data (March Annual Demographic Files, 1995-2000) are used to profile the economic status of current and potential disabled widows. The analysis, including comparison with other widows, provides strong evidence of economic need among disabled widows with, for example, 44% of disabled widow beneficiaries, ages 50-59, having below-poverty incomes compared with 15% of like-aged non-disabled widows. We conclude that serious consideration should be given to extending eligibility to all widow(er)s disabled before the normal retirement age; to providing a benefit equal to 100% of the deceased spouse's private insurance amount (PIA); to eliminating the unnecessarily restrictive seven-year rule; and to protecting beneficiaries from losing their eligibility to Medicaid. Even in the context of today's heated Social Security debate, we suggest that a rare opportunity may exist to garner bipartisan support for meaningful, low-cost improvements, in a benefit that primarily targets women.     

Relations between physical activity and behavioral and perceptual correlates among midwestern college students

OBJECTIVE: Given the inconsistent findings in the literature, the authors' purpose in this study was to examine the associations between physical activity and behavioral and perceptional correlates, such as binge drinking, cigarette smoking, fruit or vegetable consumption, and weight perceptions, among midwestern college students. PARTICIPANTS AND METHODS: The authors invited a convenience sample of 1,200 undergraduate college students enrolled in the 2004-2005 academic year in 4 different midwestern universities to participate in a survey. Of the 1,163 students who participated in the survey, a total of 1,134 usable surveys were received (response rate of 94.5%). RESULTS: Hierarchical multiple logistic regression analyses indicated that smoking, perceived weight, and consumption of fruit were independent predictors of physical activity when controlling for other variables. CONCLUSIONS: Physical activity promotion requires tailored approaches that are dependent on the target segment of the college student populations.