Moments of Inertia and Graph Separators

Graphs that arise from the finite element or finite difference methods often include geometric information such as the coordinates of the nodes of the graph. The geometric separator algorithm of Miller, Teng, Thurston, and Vavasis uses some of the available geometric information to find small node separators of graphs. The algorithm utilizes a random sampling technique based on the uniform distribution to find a good separator. We show that sampling from an elliptic distribution based on the inertia matrix of the graph can significantly improve the quality of the separator. More generally, given a cost function f on the unit d-sphere Ud, we can define an elliptic distribution based on the second moments of f. The expectation of f with respect to the elliptic distribution is less than or equal to the expectation with respect to the uniform distribution, with equality only in degenerate cases. We also demonstrate experimentally that the benefit gained by the use of the additional geometric information is significant. Some previous algorithms have used the moments of inertia heuristically, and suffer from extremely poor worst case performance. This is the first result, to our knowledge, that incorporates the moments of inertia into a provably good strategy.     

Using Remote Sensing to Evaluate Environmental Institutional Designs: A Habitat Conservation Planning Example

Objective. Satellite-based remote-sensing analysis is a beneficial, yet underused, tool for environmental policy, planning, and evaluation. We identify its benefits and costs to encourage social scientists to consider the use of remote sensing as a tool for planning and evaluating environmental institutions. Methods. We analyze two multispectral Landsat Thematic Mapper satellite images to evaluate a habitat conservation plan (HCP) implemented pursuant to the Endangered Species Act. Results. Image analysis provides useful broad spatial scale information on HCP performance that is not discernible to the naked eye or through other methodologies. Conclusions. Satellite image analysis should be considered as a tool for planning and evaluating environmental institutional designs—despite the financial costs and requisite technical training. These images provide ecological and land cover change information that may not be available elsewhere. We provide lessons learned to help make analysts cognizant of some important issues surrounding the use of satellite-based imagery for environmental institutional analysis.     

ASA certification as cooptation

We provide a brief overview of the American Sociological Association’s Ph.D. Certification Program and question the need for, and justification of, certifying sociologists. Essentially, the ASA certification mechanism, as implemented, is nonsociological, emphasizing presumed defects in the individual to the neglect of wider, systemic forces impinging on our discipline. If certification of sociologists is warranted, a view difficult to support given the small number of applicants for certification since 1986, we suggest departmental accreditation—a more sociological approach that emphasizes the value of the discipline, in and of itself. His research interests include political sociology, stratification and contemporary issues affecting the discipline. His research foci include rural and agricultural issues and the sociological employment market and profession.     

Public Opposition to a Proposed Nuclear Waste Repository in Canada: An Investigation of Cultural and Economic Effects

Residents of four northern communities were surveyed about Atomic Energy of Canada Limited's proposal to site an underground repository for high-level nuclear waste somewhere in the Canadian Shield. Opposition to the repository was relatively strong in all communities, but was strongest among aboriginal respondents. Path analysis revealed that trust in nuclear regulators, faith in science and technology, and anticipated net costs were important mediators of this effect. Aboriginals were less trusting, exhibited less faith in science and technology, and perceived the costs associated with the repository to be higher than their nonaboriginal counterparts. No support was found for the hypothesis that, after controlling for aboriginal status, financially insecure individuals would display greater support for the nuclear waste repository than financially secure individuals. Policy implications for balancing perceived risks and siting needs are discussed.