Environmental Science & Technology Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/2748

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    Climate Change Impacts and Adaptations in Eastern US Crop Production
    (2017) Salazar Lahera, Natalia; Hill, Robert L; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Climate change is affecting crop production in the Eastern US and is expected to continue doing so unless adaptation measures are employed. In the first study, we conducted surveys and interviews to identify crop management practices currently used as adaptations in the Mid-Atlantic US. The results pointed to a variety of water and soil management practices, changes in crop characteristics, and changes in planting dates. In the second study, we used the Agricultural Policy/Environmental eXtender (APEX) model to evaluate future climate change impacts and adaptations in Eastern US corn-soybean rotation systems. The effects of climate change on yields ranged from decreases to increases, generally improving with latitude and worsening with time. Climate change affected corn yields more negatively or less positively than soybean yields. No-tillage and rye cover cropping did not serve as effective adaptations in regards to yields. In fact, planting rye after corn and soybeans reduced corn yields.
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    MODEL OF EXERCISE PERFORMANCE WHILE WEARING A RESPIRATORY PROTECTIVE MASK
    (2004-06-29) Chiou, Yinghsiang; Johnson, Arthur T; Biological Resources Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This model emphasized respiratory responses and incorporated mathematical descriptions of experimental results obtained from exercising humans. Prediction equations for tidal volume, anaerobic threshold, minute volume, respiratory work, and performance time were included, as well as dynamic changes in each. This model can help to design future respirators, aid workers wearing respirators, and regulate occupational health and safety. In general, the current model can predict performance time when subjects exercise both with and without masks. The current model was fitted for 30% and 80% VO2max of experimental data from the Human Performance Laboratory (University of Maryland, College Park). The results showed predicted values were reasonable and closer to the experimental data. Results of physiological values and performance times showed that the model structure was valid and that the model was capable of making rational predictions of the average effects of respirator wear on the pulmonary system during physical activity.