The Use of Generalized Estimating Equations for Risk Assessment in Developmental Toxicity

This paper reviews and compares several approaches to fitting dose-response models to developmental toxicity data. The main issue of interest is how to appropriately account for litter effects. Among the approaches reviewed are Beta Binomial models, models that attempt to characterize the litter effect through the use of covariates, and models that avoid the complication of correlated offspring by modeling "affected litter" rather than fetus-specific outcomes. Finally, we discuss our recommended approach, which is to use Generalized Estimating Equations, or quasi-likelihood. We give a number of reasons for preferring the latter and illustrate its application with an example.     

Probabilistic Connotations of Carcinogen Hazard Classifications: Analysis of Survey Data for Anchoring Effects

A study was undertaken to test for anchoring effects when numerical probabilities were elicited for carcinogen hazard designations. Subjects were asked to assign probabilities to both probable and possible. The sequence was randomly varied so that half of the subjects evaluated probable first and half evaluated possible first. While there was no consensus on the numerical probabilistic meanings assigned to these verbal expressions, in general, probable was assigned a higher probability than possible and there were specific values that were assigned frequently, indicating some consistency in interpretation. There appeared to be a fairly constant scaling factor between the probabilities assigned to the designations. Anchoring was manifested in two ways: a smaller difference between the designations when they were evaluated in sequence than when they were evaluated in isolation, and assignment of readily accessible "benchmark" values such as 50% and 75%.     

A Survey of 100 Community Colleges on Student Substance Use,Programming, and Collaborations

Abstract

Objective: The objective was to survey community college personnel about student substance use, and infrastructure (staff and funding), programs, and collaborations dedicated to substance use prevention. Participants: The sample included 100 administrators, faculty, and health services staff at 100 community colleges. Methods: Participants completed a Web-based survey. Results: Participants reported a number of alcohol and other drug (AOD) related concerns. Despite limited staff and funding dedicated to AOD, institutions are implementing a number of programs, although many are not implementing some of the programs popular at traditional 4-year colleges. They are also collaborating with a number of on- and off-campus groups. The availability of staff and funding dedicated to AOD, and the presence of residence halls, is associated with health programming and substance abuse collaborations. Conclusions: Results suggest that there is a need for increased research to understand the most effective AOD prevention strategies for community colleges.     

Extended structures of mediation: Re-examining brokerage in dynamic networks

In this paper we revisit the concept of brokerage in social networks. We elaborate on the concept of brokerage as a process, identifying three distinct classes of brokerage behavior. Based on this process model, we develop a framework for measuring brokerage opportunities in dynamic relational data. Using data on emergent inter-organizational collaborations, we employ the dynamic brokerage framework to examine the relationship between organizational attributes and coordination in the evolving network. Comparing the findings of our process-based definition with traditional, static approaches, we identify important dimensions of organizational action that would be missed by the latter approach.     

Reports of Conferences,Institutes, and Seminars

Five reports cover the 2009 Ohio Valley Group of Technical Services Librarians Conference, the COUNTER and Usage Data webinar, the 2009 Acquisitions Institute at Timberline Lodge, the 2009 North American Serials Interest Group Conference, and selected sessions of the 2009 annual conference of the American Library Association in Chicago, Illinois.     

An adaptive estimatcr frequently used in material fatigue testing

Small sample sizes in material fatigue tests give rise to an adaptive estimator of the 100(1-P)% normal percentile, which is the 100P% survival load. The mean squared relative efficiency of the best invariant estimator of normal percentiles to the adaptive estimator is dependent upon the unknown parameters only through the coefficient of variation. The adaptive estimator is shown to be more locally efficient than tl-:ebest invariant estimator over a subset of the parameter space. However, in the extreme values of P the coverage probabilities of the adaptive estimator provide little more protection than a traditional point estimator over the range of preference based on mean squared relative efficiency.     

Examining the historical and present energy metabolism of a Rust Belt City: Syracuse,NY 1840–2005

Early cities depended on local, solar-based energy resources for their metabolism. Over time, cities have become increasingly dependent on fossil fuels, both directly and indirectly, as they facilitate exploitation of solar resources from much farther away. Alternatives to fossil fuels, typically generated locally, often provide lower surplus energy to society. As cities consider the transition back to solar-based energy resources, it becomes necessary to understand the capability of the solar-based economy to provide e.g. energy (including food) from nearby lands. To do so, we compared the energy metabolism (respiration) of a typical rust-belt city, Syracuse, NY, with the net primary production in the surrounding county (production) over its development (1840–2005). We calculated the ratio of respiration to production (R:P) and examined how this ratio changed during the periods of industrialization, shifts in major fuel types, and deindustrialization. We found that from 1840 to 1950 respiration became increasingly centralized in the urban core; since then it has become more diffused. Urban respiration exceeded production in the county by 9:1 in 1930, and it remains just under 2:1 today. Respiration reached an absolute (67 PJ) and a per capita (339 GJ) maximum in 1970, then fell by 40 % and 20 % respectively, due to deindustrialization and population losses. Conversely, production increased 480 % from its lows in 1930 because of reforestation and improved agricultural yields. What this means is that to achieve a higher P:R ratio requires either increased production of food and fuels in areas surrounding the city, or decreased per capita energy consumption.