Two environmental control chamber experiments were conducted to study the effects or temperature, nitrogen, and light intensity on the growth and physiological effects on Tifgreen bermudagrass, Cynodon dactylon (L) Pers., and Cohansey bentgrass, Agrostis palustris Huds. Each of the grasses was included in a field experiment to study the influence of nitrogen rates on carbohydrate reserves at different seasons. Increased temperatures with bentgrass caused decreased carbohydrates, root weights, and final growth of tops, but increased nitrogen content and respiration. NAR in bentgrass was highest at 75 F. The respiration rate, top growth, and carbohydrate content of bermudagrass tended to increase with temperature, but root weights and NAR were highest at medium temperatures. High N generally increased top growth, NAR, respiration, and nitrogen content, but lowered the carbohydrates and root growth for both grasses. Bentgrass, grown at 95 F during the day-, declined in yield, root growth, NAR, and respiration as night temperatures increased from 60 to 90 F. With bermudagrass HAR, top growth, and root growth were highest at 75 F and lowest at 90 F night temperatures. The AEC of bentgrass were highest at the mid-temperature, but the AEC: fer bermudagrass tended to increase with the high night temperature. Low light intensity generally decreased the yield of tops and roots, NAR, respiration, and carbohydrates, but increased the nitrogen content of both grasses. Bentgrass stolons increased in carbohydrate content during the tall and early vinter, and then declined rapidly during the spring. During the summer, the carbohydrates in bentgrass were low. The carbohydrates in bermudagrass stolons decreased during the winter and spring, increased during summer, and reached a maximum by late fall. For all experiments the oligosaccharides and monosaccharides made up a rather large portion of the AEC in bentgrass, polysaccharides being the largest fraction. Polysaccharides in bermudagrass made up the largest fraction of the AEC, the monosaccharides and oligosaccharides being less than 10% of the dry weight. / Ph. D.

Two experimental procedures are employed to value both health and environmental benefits from reducing pesticides in Uganda. The first experiment, an incentive compatible auction involves subjects with incomplete information placing bids to avoid consuming potentially contaminated groundnuts/water in a framed field experimental procedure. Three experimental treatments (information, proxy good, and group treatments) are used. Subjects are endowed with a monetary amount (starting capital) equivalent to half the country's per capita daily income (in small denominations). Two hundred and fifty seven respondents were involved in a total of 35 experimental sessions in Kampala and Iganga districts. Tobit model results indicate that subjects place significant positive values to avoid ill health outcomes, although these values vary by region, by treatment and by socio-economic characteristics. Gender differences were important in explaining bidding behavior, with male respondents in both study areas bidding higher to avoid ill health outcomes than females. Consistent with a priori expectation, rural population's average willingness to pay (WTP) to avoid ill health outcomes was lower (by 11.4 percent) than the urban population's WTP possibly reflecting the poverty level in the rural areas and how it translates into reduced regard for health and environmental improvements. Tests of hypotheses suggest (i) providing brief information to subjects just prior to the valuation exercise does not influence bid behavior, (ii) subjects are indifferent to the source of contamination: WTP to avoid health outcomes from potentially contaminated water and groundnuts are not significantly different, and (iii) the classical tendency to free-ride in public goods provision was observed, and this phenomenon was more pronounced in the urban than the rural area. The second experimental procedure involved 132 urban respondents making repeated choices from a set of scenarios described by attributes of water quality, an environmental good. Water quality is represented by profiles of water safety levels at varying costs. Analysis using the conditional (fixed effects) logit showed that urban subjects highly discount unsafe drinking water, and were willing to pay less for safe agricultural water, a result not unexpected considering that the urban population is not directly involved in agricultural activities and thus does not value agricultural water quality as much as drinking water quality. Results also showed that subjects' utility increased with the cost of a water sample (inconsistent with a downward sloping demand curve), suggesting perhaps that they perceived higher costs to be associated with higher water quality. Some theoretically inconsistent results were obtained with choice experiments. / Ph. D.

Human clinical (n=131) and environmental (n=226) isolates of the Mycobacterium avium-intracellulare and M. scrofulaceum (MAIS) complex were screened for plasmids in an effort to increase knowledge about the genetics and epidemiology of these pathogenic bacteria. Approximately 50% of the clinical MAIS isolates from New York, Maryland, Virginia, South Carolina, and Georgia contained one or more plasmids. On the basis of plasmid content, aerosol MAIS isolates more closely resembled human MAIS isolates than did MAIS isolates from the other environmental sources examined (dust, soil, sediment, and water). Plasmid profiles were remarkably heterogenous, and isolates with identical profiles were rarely encountered. However, a 115 megadalton (Md) plasmid was detected in 15 mercury resistant human and environmental isolates. In one of these isolates (M. scrofulaceum W262) the presence of the 115 Md plasmid was shown to correlate with the presence of an NAD(P)H dependent mercuric reductase. Plasmids with molecular weights of 8.8, 11.2, 14.2, 16.9, 17.9, and 18.3 Md were also common among both human and environmental isolates. On the basis of molecular weight, 36 distinct plasmids were detected; their sizes ranged from 7 to 230 Md. It was concluded that human and environmental MAIS isolates share a number of plasmids with identical molecular weights and that plasmids can serve as useful entities in genetic and epidemiologic studies of this group of extremely slow-growing, poorly understood human and animal pathogens. / Ph. D.

Call number: LD2668 .T4 1962 A30

Call number: LD2668 .T4 1962 D45

Call number: LD2668 .T4 1962 W35

Call number: LD2668 .T4 1964 E34 / Master of Science

LD2668 .T4 1966 A517 / Master of Science

Call number: LD2668 .T4 1966 K48 / Master of Science

Call number: LD2668 .T4 1966 K76 / Master of Science