Reassessment of the Cross-Florida Barge Canal: A probability approach

This reassessment of the Corps of Engineers' study of the Cross-Florida Canal demonstrates the application of the Weibull probability distribution to handle uncertainty in benefit-cost analysis and illustrates the distribution's use to incorporate environmental considerations in project analysis. With range and probability assumptions to reflect the criticisms of the Corps' study, it is shown that the Canal was a high-risk project even with the inappropriately low discount rate used. Use of the Weibull distribution is shown to be superior to the usual point estimates and range sensitivity tests in benefit-cost analysis.     

Substance use and functional impairment among adolescents directly exposed to the 2001 World Trade Center attacks

The relationship between exposure to the World Trade Center (WTC) attacks, increased substance use, functional impairment and mental health service use, controlling for depression and post-traumatic stress disorder, was assessed through an in-school survey of directly exposed students (N = 1040) attending the five middle and five high schools nearest the WTC. The survey was conducted 18 months after the attacks. Students with one WTC exposure risk factor had a five-fold increase in substance use, while those with three or more exposure risks had a nearly 19-fold increase. Increased substance use was associated with impaired school work, school behaviour and grades. Students reporting increased substance use were nearly twice as likely to want help but were no more likely than asymptomatic students to receive services. Adolescents reporting increased substance use, without co-morbidity, were less likely to receive psychological services than others. Attention to the needs of substance-using adolescents exposed to disaster is needed.     

Determination of the initial exothermic reaction of shredded tyres with wire content.

This paper presents the cause of exothermic reactions in shredded tyre with exposed wire content in shredded tyre piles. Data indicate that the oxidation of exposed steel wires is the exothermic reaction in shredded tyre embankments. This would lead to spontaneous combustion. Reaction of the steel with the sulphur or the carbon black appears not to be the source of the exothermic. Laboratory tests have been conducted to determine the heat transfer properties of the materials that compose tyres (i.e., tyre rubber and wires) by using a hot-plate apparatus. In addition, one-dimensional heat conduction experiments were conducted to compare the flow of heat through the materials while varying the physical and environmental conditions. The physical conditions were the size of tyre shred, water content, and wire contents. An exothermic reaction occurred when exposed wire was present but not when it was absent. A one-dimensional heat transfer equation was developed, and parametric studies were conducted to verify the laboratory model. Exothermic reaction was found to increase linearly with temperature, size and shape of the shredded tyres, density, amount of wire in shredded tyres, and water content.     

THE EFFICIENCY OF WATER PRICING: A RATE OF RETURN ANALYSIS FOR MUNICIPAL WATER DEPARTMENTS1

ABSTRACT: The rate of return on invested capital can be used as a guide to resource allocation by municipal water departments (MWD's) in the same way it is used in the private sector. To achieve economic efficiency, the target rate of return for MWD's should be the market rate of return as an approximation to the opportunity cost of capital. The actual internal rate of return for a sample of 30 California MWD's for the period 1970-1982 is calculated for this study. The operating internal rate of return varies across the sample MWD's from less than 2 percent to 14 percent. If 10 percent is taken as the opportunity cost of capital, 25 of the 30 MWD's were inefficient; i.e., earned less than 10 percent. Half the sample earned less than 5 percent. An examination of potential causes of low rates of return shows that low average water prices are the primary reason for the low rates of return. For efficient operation, MWD's should set a target rate of return equal to the opportunity cost of capital and adjust water prices so as to achieve that target.     

global warming — uncertainties,effects, and policy options

Environmental policy making is a challenging task. Often the scope of an issue is not fully comprehended, and its future impact is even less well understood. Global warming is one of these environmental issues. The issue is made more complex because, first, there is a question of whether it is a problem at all and, second, unilateral policy making by one nation may not be sufficient or even significant to tackle the problem globally. This article outlines the scientific factors that contribute to global warming and discusses the uncertainties involved. The authors then discuss the ramifications of taking action (policy making) and failing to act (doing nothing) against the background of global warming, greenhouse gases, and cost-benefit analysis. The article concludes by reporting the results of a multidisciplinary panel of experts composed of scientists, economists, and policy analysts who commented on various policy options.     

AIRBORNE THERMAL MAPPING OF A “FLOW-THROUGH” LAKE IN THE NEBRASKA SANDHILLS1

The Sandhills region represents a tremendous water resource for the State of Nebraska. Small shallow lakes, marshes, and subirrigated meadows are abundant due to interactions between ground water and surface water. One theory relating ground water to lake-flow systems in the Sandhills has been termed the “flow-through” concept. Thermal-infrared remotely acquired images document the flow-through model for a test site in Western Nebraska.     

The effects of social support on nuclear worker responses to the Three Mile Island accident

This study examines the effects of social support on the reactions of nuclear workers at the Three Mile Island plant and a comparison site to stress during the 1979 crisis. Results show broad main effects of social support on stress, strain, and health outcome variables. Moderating effects of support are highly selective and become less extensive as the hypothesized stress process moves from stress to strain to health outcomes. Findings are compared between the two nuclear plants and with other studies conducted under non-crisis conditions.