Three models of OPEC leadership and policy in the aftermath of Iran

Collapse of the Shah's regime has transformed Iran's attitude regarding oil production policy. The nature of OPEC leadership is changing as well. Three models examine the nature of this leadership inside OPEC: (1) the conventional price leadership model, (2) a model emphasizing a concept of egalitarian leadership, and (3) a team model composed of coalitions. The three models establish the limits within which OPEC leadership is exercised. A composite model drawing upon all three sets of results suggests that Saudi Arabia shapes cartel policy not by itself, but through a dominant coalition of states. For most of the period 1969–1978 this coalition has been stable. Following the unsettling changes of 1973, cooptation of Iran into the dominant coalition in 1974 was an important step in achieving a new level of stability. But during the turbulence of regime transformation in Iran, the nature of the governing coalition appears to have changed. One consequence may be that in the future Saudi Arabia will yield more willingly to arguments heard within OPEC on behalf of upwards price pressure, especially in an atmosphere of growing political isolation and overall tight supply.     

Biological Markers of Environmental and Ecological Contamination: An Overview

An approach, using biomarkers (biological responses) for assessing the biological and ecological significance of contaminants present in the environment is described. Living organisms integrate exposure to contaminants in their environment and respond in some measurable and predictable way. Responses are observed at several levels of biological organization from the biomolecular level, where pollutants can cause damage to critical cellular macromolecules and elicit defensive strategies such as detoxication and repair mechanisms, to the organismal level, where severe disturbances are manifested as impairment in growth, reproduction, developmental abnormalities, or decreased survival. Biomarkers can provide not only evidence of exposure to a broad spectrum of anthropogenic chemicals, but also a temporally integrated measure of bioavailable contaminant levels. A suite of biomarkers are evaluated over time to determine the magnitude of the problem and possible consequences. Relationships between biomarker response and adverse ecological effects are determined from estimates of animal health and population structure.     

Estimation of the mutagenic potency of environmental chemicals using short-term bioassay

The Ames Salmonella test is a widely used bioassay method for assessing the mutagenic potency of a potential carcinogen. The test is quick and reliable, and exploits the correlation that exists between mutagenic potential and carcinogenic potential. The data for this case study came from an international study involving 20 laboratories in nine countries. The laboratories participated in a designed experiment in which substances (complex chemical mixtures of the type encountered in the environment) were evaluated for mutagenicity using the Ames test. A stringent protocol was followed. The study's principal aim was to investigate intra- and inter-laboratory variation in test results. The data consist of counts of revertant Salmonella colonies at each of six dose levels of a substance. The data were obtained for each of five test substances from each participating laboratory. The bioassays were carried out according to a prescribed factorial experimental design. Three sets of analysts participated in this case study. They were asked to model the dose-response relationship for two substances, to develop an index of the strength of the relationship, and to assess intra- and inter-laboratory variation in bioassay results.     

Monitoring the metropolitanization process

Alternative approaches have led to different interpretations of the metropolitanization process in the United States. We identify and illustrate several methods and procedures for monitoring metropolitan-nonmetropolitan population change using the 1950-1980 U.S. decennial censuses. Two basic approaches are compared: constant area approaches and component methods. In addition, we assess the effects of changing metropolitan definitions on metropolitan-nonmetropolitan growth. The results clearly reveal that the underlying mechanics of metropolitanization not only are complex but have changed substantially during the 1950-1980 period. We conclude with observations regarding the use of these procedures in future research.     

Self-control training with maltreating parents

Seeking a method of intervention based on research about correlates of child maltreatment, the authors find that small-group, short-term training in self-control and child management skills gives parents the tools to better handle family stress and develop supportive social networks.     

A POPULATION PROFILE OF VERY OLD MEN AND WOMEN IN THE UNITED STATES

This article presents the first population profile of men and women age 85 and over. It was developed with the 1980 census PUMS sample A, of which nearly 70% were women. Men were better off than women in both socioeconomic and relational characteristics in that they had higher personal incomes from nearly all sources and were far more likely to be married and living independently. They were not found in nursing homes in as great a proportion as were very old women. In a sense, then, the generalizations about the very old have a female bias.     

Models of gambling and gambling addictions as perceptual filters

Models, in the sense of loosely entertained clusters of beliefs, attitudes, assumptions and expectations which direct the work of researchers and clinicians, also act as perceptual filters, tending to focus the attention of those who use them on certain aspects of reality and relegating to the background or ignoring altogether other aspects of the field of study and action. The central characteristics of social learning and of medical models are briefly reviewed and they are compared as perceptual filters for their distorting effects on research in gambling and in gambling addictions and on intervention strategies for problem gamblers. It is concluded that the exclusive predominance of any one model leads to the impoverishment of both research and intervention.     

Parametric discounting

A parametric approach to the problem of selection from amongst alternative investment opportunities is considered in a discounted cash flow framework. The approach employs differential cash flows, an uncertain planning horizon and a nested approach to composing cash flow parameters. This promotes consistent treatment of alternative investments, clarifies the effects of uncertainty, avoids some of the defects of internal rate of return and payback period criteria and allows direct comparison of best and next best options as primal and dual versions of the same model. Net present value, internal rate of return, annual average cost or payback period assessments may be selected post analysis. A domestic wall insulation example is used for illustrative purposes. This example is related to the hydroelectric power development decision which gave rise to the approach.