MANAGING THE GREAT LAKES COMMONS: AN EVALUATION OF RECENT INSTITUTIONAL CHANGES

Resource /Energy Economics and Policy,

ALTERNATIVE PRICE SPECIFICATION FOR MUNICIPAL WATER DEMANDS: AN EMPIRICAL TEST

Based on data from 92 Minnesota cities, the analyses shows that neither marginal price or average price appear as the better predictor of demand. The price elasticity of demand ranges from -. 17 for marginal price in the linear model to -.27 for average price in the log linear model. It appears from the analysis that many consumers are unaware of the marginal price of their water. Thus utilities should simplify their pricing structures and present consumers with an easy to understand costs of water such as the cost of six hours of lawn watering.Demand and Price Analysis, Public Economics,

An analysis of a preservice teacher structural equation model under varying assumptions and measurement conditions

The purposes of this study were to develop a structural equation model of preservice teacher variables and to examine alternative methods of testing this model under different assumptions and measurement conditions. A conceptual model was posited to examine variables related to job expectations, academic ability, pre-student teaching preparation, satisfaction with cooperating teacher, self-rated student teaching performance, and quality of teacher preparation program;From this conceptual model of preservice teacher variables, five empirical models were developed and analyzed. Models I and II utilized single indicators computed as composite means of the respective observed standardized indicators. Model I assumed variables were measured without error. Model II utilized the same indicators as Model I but adjustments were made to allow for measurement error. Models III and IV used a multiple indicator approach with Model III assuming no measurement error, while Model IV adjusted for measurement error. Model V, assuming no measurement error, utilized the multiple indicators from Models III and IV but analyzed them independently. The method of analysis for Models I, III and V was multiple linear regression. Models II and IV were analyzed using the LISREL approach;Results of the analyses lent moderate support for the conceptual model. The results of two single indicator models indicated a satisfactory fit of the models to the data. However, the multiple indicator model adjusting for error did not provide a good fit. In addition to the individual model tests, parameter estimates from the different models were compared and discussed

Modeling Social Transmission Dynamics of Unhealthy Behaviors for Evaluating Prevention and Treatment Interventions on Childhood Obesity

Research evidence indicates that obesity has spread through social networks, but lever points for interventions based on overlapping networks are not well studied. The objective of our research was to construct and parameterize a system dynamics model of the social transmission of behaviors through adult and youth influence in order to explore hypotheses and identify plausible lever points for future childhood obesity intervention research. Our objectives were: (1) to assess the sensitivity of childhood overweight and obesity prevalence to peer and adult social transmission rates, and (2) to test the effect of combinations of prevention and treatment interventions on the prevalence of childhood overweight and obesity. To address the first objective, we conducted two-way sensitivity analyses of adult-to-child and child-to-child social transmission in relation to childhood overweight and obesity prevalence. For the second objective, alternative combinations of prevention and treatment interventions were tested by varying model parameters of social transmission and weight loss behavior rates. Our results indicated child overweight and obesity prevalence might be slightly more sensitive to the same relative change in the adult-to-child compared to the child-to-child social transmission rate. In our simulations, alternatives with treatment alone, compared to prevention alone, reduced the prevalence of childhood overweight and obesity more after 10 years (1.2–1.8% and 0.2–1.0% greater reduction when targeted at children and adults respectively). Also, as the impact of adult interventions on children was increased, the rank of six alternatives that included adults became better (i.e., resulting in lower 10 year childhood overweight and obesity prevalence) than alternatives that only involved children. The findings imply that social transmission dynamics should be considered when designing both prevention and treatment intervention approaches. Finally, targeting adults may be more efficient, and research should strengthen and expand adult-focused interventions that have a high residual impact on children

A direct D-bar reconstruction algorithm for recovering a complex conductivity in 2-D

A direct reconstruction algorithm for complex conductivities in $W^{2,\infty}(\Omega)$, where $\Omega$ is a bounded, simply connected Lipschitz domain in $\mathbb{R}^2$, is presented. The framework is based on the uniqueness proof by Francini [Inverse Problems 20 2000], but equations relating the Dirichlet-to-Neumann to the scattering transform and the exponentially growing solutions are not present in that work, and are derived here. The algorithm constitutes the first D-bar method for the reconstruction of conductivities and permittivities in two dimensions. Reconstructions of numerically simulated chest phantoms with discontinuities at the organ boundaries are included.Comment: This is an author-created, un-copyedited version of an article accepted for publication in [insert name of journal]. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at 10.1088/0266-5611/28/9/09500