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- Language: English
This thesis addresses the following questions: What are the best methods to test the effects of tolaasin, cephalexin and laser on the biofilms of S. aureus and S. epidermidis? Does tolaasin prevent or disrupt biofilm formation in S. aureus and S. epidermidis? Does tolaasin work synergistically with cephalexin to prevent biofilm growth and maturation in S. aureus and S. epidermidis? And, what effects does laser treatment have on E. faecalis biofilms? In order to answer these questions, tolaasin was isolated from P. tolaasii, and biofilms were pre-treated with tolaasin. Trials were performed with tolaasin, cephalexin, or a combination of both. The effectiveness of each treatment was determined by observing the biofilm growth. The protocols were then optimized and trials were repeated. Additionally, E. faecalis biofilms were exposed to laser treatment. Using confocal microscopy, the biofilms were observed and quantitative results were used to determine the effectiveness of the treatment. Overall, the results indicated that tolaasin has little effect on biofilm growth. However, further investigation is necessary to confirm these results due to some inconsistent data obtained over the course of the trials. Variations and improvements to the protocol are necessary to accurately determine tolaasin’s potential role in healthcare. Finally, the results of the laser trials suggest that EDTA in conjunction with laser treatment could be useful in cleaning root canals and eliminating post-procedural biofilms—thereby preventing infections.
Problem: The prospect that urban heat island (UHI) effects and climate change may increase urban temperatures is a problem for cities that actively promote urban redevelopment and higher densities. One possible UHI mitigation strategy is to plant more trees and other irrigated vegetation to prevent daytime heat storage and facilitate nighttime cooling, but this requires water resources that are limited in a desert city like Phoenix.
Purpose: We investigated the tradeoffs between water use and nighttime cooling inherent in urban form and land use choices.
Methods: We used a Local-Scale Urban Meteorological Parameterization Scheme (LUMPS) model to examine the variation in temperature and evaporation in 10 census tracts in Phoenix's urban core. After validating results with estimates of outdoor water use based on tract-level city water records and satellite imagery, we used the model to simulate the temperature and water use consequences of implementing three different scenarios.
Results and conclusions: We found that increasing irrigated landscaping lowers nighttime temperatures, but this relationship is not linear; the greatest reductions occur in the least vegetated neighborhoods. A ratio of the change in water use to temperature impact reached a threshold beyond which increased outdoor water use did little to ameliorate UHI effects.
Takeaway for practice: There is no one design and landscape plan capable of addressing increasing UHI and climate effects everywhere. Any one strategy will have inconsistent results if applied across all urban landscape features and may lead to an inefficient allocation of scarce water resources.
Research Support: This work was supported by the National Science Foundation (NSF) under Grant SES-0345945 (Decision Center for a Desert City) and by the City of Phoenix Water Services Department. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of NSF.