Pollution and perception: Social visibility and local environmental mobilization

Why does local environmental degradation lead some communities to rebel while others remain politically complacent? This comparative analysis seeks a partial answer to that question through examination of the impacts of the social visibility of local environmental problems on political mobilization in the Great Lakes Basin. The data upon which this paper is based is drawn from original field research conducted in six environmentally contaminated communities in both the U.S. and Canada. The paper examines the efforts of industry, government and environmental organizations to manipulate the visibility of contaminants in order to promote or prevent the emergence of grass roots political activism. However, the data indicates that socially visible environmental disorganization increases local awareness of contamination, but has little bearing on the definition of that contamination as a problem requiring political action. The transformation of awareness of environmental problems into local political mobilization is not determined primarily by the social visibility of contaminants, their sources, or their impacts on the environment.     

Premarital Sexual Intercourse and Axiomatic Theory Construction*

Axiomatic theory construction was used in this study to analyze the likelihood of participation in premarital sexual intercourse by college women. The sample consisted of 754 never-married female students enrolled in a midwestern, residential university who responded to a sexual attitudes and behavior survey. Forty-eight empirical propositions concerning premarital sexual intercourse were tested, nineteen of which were found to be statistically significant. Three derived propositions were reformulated from these findings, which in turn were utilized to develop two middle-range theories: commitment theory and cultural milieu theory. These theories clearly demonstrate the role of changing personal and societal attitudes toward sexuality and perceived partner commitment in the decision to become sexually active.     

Black‐White Wage Inequality in the 1990s: a Decade of Progress

Using Current Population Survey data, we find that the gap between the wages of black and white males declined during the 1990s at a rate of about.60 percentage point per year. Wage convergence was most rapid among workers with less than 10 years of potential experience, with declines in the gap averaging 1.40 percentage points per year. Using standard decomposition methods, we find that greater occupational diversity and reductions in unobserved or residual differences are important in explaining this trend. General wage inequality tempered the rate of wage convergence between blacks and whites during the 1990s.     

Optimal allocation of sample sizes between regular banding and radio-tagging for estimating annual survival and emigration rates

Many authors have shown that a combined analysis of data from two or more types of recapture survey brings advantages, such as the ability to provide more information about parameters of interest. For example, a combined analysis of annual resighting and monthly radio-telemetry data allows separate estimates of true survival and emigration rates, whereas only apparent survival can be estimated from the resighting data alone. For studies involving more than one type of survey, biologists should consider how to allocate the total budget to the surveys related to the different types of marks so that they will gain optimal information from the surveys. For example, since radio tags and subsequent monitoring are very costly, while leg bands are cheap, the biologists should try to balance costs with information obtained in deciding how many animals should receive radios. Given a total budget and specific costs, it is possible to determine the allocation of sample sizes to different types of marks in order to minimize the variance of parameters of interest, such as annual survival and emigration rates. In this paper, we propose a cost function for a study where all birds receive leg bands and a subset receives radio tags and all new releases occur at the start of the study. Using this cost function, we obtain the allocation of sample sizes to the two survey types that minimizes the standard error of survival rate estimates or, alternatively, the standard error of emigration rates. Given the proposed costs, we show that for high resighting probability, e.g. 0.6, tagging roughly 10-40% of birds with radios will give survival estimates with standard errors within the minimum range. Lower resighting rates will require a higher percentage of radioed birds. In addition, the proposed costs require tagging the maximum possible percentage of radioed birds to minimize the standard error of emigration estimates.     

Spatial Risk Assessment Across Large Landscapes with Varied Land Use: Lessons from a Conservation Assessment of Military Lands

Spatial decision-support tools are necessary for assessment and management of threats to biodiversity, which in turn is necessary for biodiversity conservation. In conjunction with the U.S. Geological Survey-Biological Resources Division's Species at Risk program, we developed a GIS-based spatial decision-support tool for relative risk assessments of threats to biodiversity on the U.S. Army's White Sands Missile Range and Fort Bliss (New Mexico and Texas) due to land uses associated with military missions of the two bases. The project tested use of spatial habitat models, land-use scenarios, and species-specific impacts to produce an assessment of relative risks for use in conservation planning on the 1.2 million-hectare study region. Our procedure allows spatially explicit analyses of risks to multiple species from multiple sources by identifying a set of hazards faced by all species of interest, identifying a set of feasible management alternatives, assigning scores to each species for each hazard, and mapping the distribution of these hazard scores across the region of interest for each combination of species/management alternatives. We illustrate the procedure with examples. We demonstrate that our risk-based approach to conservation planning can provide resource managers with a useful tool for spatial assessment of threats to species of concern.     

The use of auxiliary variables in capture-recapture modelling: An overview

I review the use of auxiliary variables in capture-recapture models for estimation of demographic parameters (e.g. capture probability, population size, survival probability, and recruitment, emigration and immigration numbers). I focus on what has been done in current research and what still needs to be done. Typically in the literature, covariate modelling has made capture and survival probabilities functions of covariates, but there are good reasons also to make other parameters functions of covariates as well. The types of covariates considered include environmental covariates that may vary by occasion but are constant over animals, and individual animal covariates that are usually assumed constant over time. I also discuss the difficulties of using time-dependent individual animal covariates and some possible solutions. Covariates are usually assumed to be measured without error, and that may not be realistic. For closed populations, one approach to modelling heterogeneity in capture probabilities uses observable individual covariates and is thus related to the primary purpose of this paper. The now standard Huggins-Alho approach conditions on the captured animals and then uses a generalized Horvitz-Thompson estimator to estimate population size. This approach has the advantage of simplicity in that one does not have to specify a distribution for the covariates, and the disadvantage is that it does not use the full likelihood to estimate population size. Alternately one could specify a distribution for the covariates and implement a full likelihood approach to inference to estimate the capture function, the covariate probability distribution, and the population size. The general Jolly-Seber open model enables one to estimate capture probability, population sizes, survival rates, and birth numbers. Much of the focus on modelling covariates in program MARK has been for survival and capture probability in the Cormack-Jolly-Seber model and its generalizations (including tag-return models). These models condition on the number of animals marked and released. A related, but distinct, topic is radio telemetry survival modelling that typically uses a modified Kaplan-Meier method and Cox proportional hazards model for auxiliary variables. Recently there has been an emphasis on integration of recruitment in the likelihood, and research on how to implement covariate modelling for recruitment and perhaps population size is needed. The combined open and closed 'robust' design model can also benefit from covariate modelling and some important options have already been implemented into MARK. Many models are usually fitted to one data set. This has necessitated development of model selection criteria based on the AIC (Akaike Information Criteria) and the alternative of averaging over reasonable models. The special problems of estimating over-dispersion when covariates are included in the model and then adjusting for over-dispersion in model selection could benefit from further research.     

Revising and updating the inventory of cross-cultural sensitivity

The following article outlines research conducted to examine cross-cultural sensitivity in a sample of 949 incoming university students in the USA. The study was conducted during the process of updating an existing measure of cross-cultural sensitivity known as the Inventory of Cross-Cultural Sensitivity (ICCS), and to examine the various levels of understanding among the students. Additionally, data were gathered to determine whether there was any relationship between the results and the demographic factors commonly cited in the literature. Results of the study indicate that the updated version of the ICCS, the ICCSv2, is a more robust and reliable measure of intercultural sensitivity for a specific group of freshmen students. Recommendations are made for future research.     

Determinants of 1980 to 1990 Net Migration in Texas Counties: The Role of Sustenance Specialization and Dominance in International Ecosystems

Abstract Patterns of 1980–1990 migration differ markedly from those of the 1970s but they have received little conceptual or empirical analysis because of limited data and because their diversity has resisted theoretical generalization. An expanded human ecological perspective incorporating international dimensions is hypothesized to explain differentials in migration during the 1980s. Counties with key functions which operate in international ecosystems in which the United States is dominant are hypothesized to control more resources and to have the highest net inmigration. Hypotheses are tested using regression analyses of 1980–1990 net migration for Texas' 254 counties. The results generally confirm that key functional activities were related to migration but less so in nonmetropolitan areas. Implications for rural development and for further research are discussed.