Chamaecrista Fasciculata In Tallgrass And Sand Prairies: The Potential For Differential Responses

Successful establishment of a diversity of native species has become an important goal for restoration site managers to achieve, however as seed sources for a species may occur in habitats with different abiotic and biotic characteristics. Consequently, seeds from different sources may vary in their success in a restoration. Chamaecrista fasciculata, a native prairie species, occurs in two divergent prairie types - tallgrass and sand prairies. Tallgrass prairies have a moist soil with dense vegetation; in contrast, sand prairies have a well-drained sandy soil with sparse vegetation. I propose differential selection acting on populations in these prairie types would affect their seeds success in restorations. Given the denser vegetation of the tallgrass prairies, plants must be capable of competing for light resources, thus I predict the plants from tallgrass seed sources have a better competitor tolerance and would be more successful in a reconstructed tallgrass prairie. To assess the effect of sand vs. tallgrass prairie seed sources, I conducted a greenhouse and a common garden study. In the greenhouse study, all plants from the three tallgrass and three sand prairies were reduced in height, biomass, and fruit production when exposed to a competitor (Schizachyrium scoparium). Further, sand prairie plants had greater fruit production while tallgrass prairie plants flowered and senesced earlier. In the common garden study, plants within the no trim treatment had a greater relative leaf area lost to herbivory in late seasonal measurements. However, my results found no evidence of tallgrass seed sources showing any greater competitive tolerance or relative success in comparison to sand prairie seed sources in the greenhouse and common garden studies. Still, different prairie types were found to differ in some observed traits in a greenhouse setting. Further study is necessary to determine if the observed differences in the greenhouse and the native prairies would impact restorations

"Fear of stigma is stronger than fear of death": a workplace initiative to reduce sickness and death due to HIV/AIDS among health staff in Malawi

Mexico AIDS Conference 200

Construction Cost Sensitivity of a Lignocellulosic Ethanol Biorefinery

The technology has been developed to convert feedstock with cellulose content into ethanol. However, ethanol produced from cellulosic feedstock is the same as ethanol distilled from grain. The objective of research is to determine the price per gallon of ethanol needed so that producing lignocellulosic based ethanol become economically feasible.Environmental Economics and Policy, Production Economics,

Traffic Sign Detection and Identification

Previous studies using eye-trackers have suggested that drivers can extract information from traffic signs and markings without fixating them. The first study reported here examined the angle of gaze away from signs that enables sign detection: detection conspicuity angle. A second study examined the angle of gaze away from signs that enables identification of the signs’ messages: identification conspicuity angle. Because conspicuity is viewed as a product of the properties of objects and their surrounding environment, both studies manipulated the background of the signs. Detection conspicuity was sensitive to the background environment, particularly for regulatory signs, for which detection conspicuity was reduced with light-colored or cluttered backgrounds. Background environment had little measureable effect on sign message identification. It is recommended that sign backgrounds be considered when locating signs, and that if the background does not provide adequate contrast, conspicuity enhancement strategies should be considered

Assessing the Distraction Potential of Changeable Highway Message Signs

Two experiments were conducted to assess how changeable message signs (CMS) within the right-of-way affect driver behavior and attention. Experiment 1 evaluated whether repeated exposure to irrelevant messages would cause drivers to fail to respond to a safety critical message. Experiment 2 evaluated whether the presence of a driving irrelevant message designed to attract attention would cause drivers to fail to respond to a hazard in the roadway. In both experiments, drivers completed a lengthy (about 50 min) driving simulation in a freeway scenario with CMS every 0.8 km (0.5 mi). Dependent measures were gaze location, response to safety critical message (Exp. 1), and response to spilled load in roadway (Exp. 2). It was found that (1) when headways were short, drivers tend to focus on the roadway and not on a CMS; (2) repeated exposure to irrelevant messages did not cause drivers to miss safety critical messages; (3) salient CMS images (changing faces) did not cause failures to detect a roadway hazard, and (4) the frequency and duration of looks to salient images and travel time messages were similar

L\'evy Distribution of Single Molecule Line Shape Cumulants in Low Temperature Glass

We investigate the distribution of single molecule line shape cumulants, $\kappa_1,\kappa_2,...$, in low temperature glasses based on the sudden jump, standard tunneling model. We find that the cumulants are described by L\'evy stable laws, thus generalized central limit theorem is applicable for this problem.Comment: 5 pages, 3 figure