published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy

This study was designed to assess the appropriateness of current standardized checklists used to measure stressful life events in a noninstitutionalized population aged 65-74 years of age. Previous studies, sampling from a younger aged population, have demonstrated a temporal association between an increase in stressful life events and psychophysiological disease. Before stress can be studied as a precipitator of disease onset in the aged, it must be determined if the instruments designed to measure stress are reliable and valid for use with the aged. Specifically, the following questions were examined: (1) Reliability--Are the checklists reliable for use with this population? (2) Relevance--Are the checklists valid for use with this population? (3) Are these events considered to be stressful for this population? (4) Does the scoring system used influence the results? (5) Are the events included on the checklists events that occur in the lives of people aged 65-74? (6) Are there other events, not on the checklists, which are stressful for older people? The data base for this study consisted of responses from 185 subjects aged 65-74 years. Each respondent completed three standardized checklists designed to measure stressful life events and a demographic sheet which included provision for respondents to write any stressful event(s) that had occurred. Results were analyzed by subscale. As a result of this study it was determined that: (1) Reliability coefficients across subscales were not sufficiently large to warrant using these checklists with this aged population. (2) The three checklists were not valid for use with this aged population. (3) Respondents in this study perceived most events as being more stressful than did a younger age standardized group. (4) Standardized weights for the events should be assigned by people aged 65-74 years. (5) Stressful life events are different for people aged 65-74 years than for younger aged people. It was recommended that the checklists be revised for use with this age population. This revision includes modifying events on the checklist and having people aged 65-74 years assign standardized weights that reflect the stressfulness of the events.

Fourteen (14) Arizona accessions and 7 Colorado accessions of Saltgrass (Distichlis spicata), collected from Arizona and Colorado and 1 Bermudagrass (Cynodon dactylon), cultivar Midiron (check), were studied in a greenhouse to evaluate their growth responses in terms of shoot dry weights and percentage of visual green under drought stress conditions. Plants were grown under normal (daily watering and weekly fertilizer application) for one year for complete establishment. Then, the plants were deprived from water for four months (January 5, 2001 - May 5, 2001). Plant clippings were harvested weekly, oven dried at 60 °C, and the dry weights were recorded. At each harvest, percentage of green cover were also estimated and recorded. After the last harvest, plants were re-watered to assess and compare the percent of recovery. Overall, the results (both shoot dry weights and the percent of the visual green) show that the A138 and A137 (Arizona accessions) were the best accessions and the C66 (Colorado accession) was the worst. Both the shoot dry weights and the percent of visual green cover decreased as the drought period progressed. In general, most of the saltgrass accessions were more tolerant to drought stress than the bermudagrass.

Saltgrass (Distichlis spicata), clonal accession WA-12, collected from Wilcox, Arizona was studied in a greenhouse to evaluate its growth responses in terms of shoot and root lengths, shoot fresh weight, and shoot and root dry weights under control and salt (sodium chloride) stress conditions. Plants were grown under control (no salt) and three levels of salt stress (100, 200, and 400mM NaCl equivalent to 6250, 12500, and 25,000 g Lᴮ¹ sodium chloride, respectively), using Hoagland solution in a hydroponics system. Plant shoots (clippings) were harvested weekly, oven dried at 60 °C, and dry weights recorded. At each harvest, both shoot and root lengths were measured and recorded. At the last harvest, plant roots were also harvested, oven dried, and dry weights were determined and recorded. The results show that the shoot and root lengths decreased with increasing the salinity levels, however, both shoot fresh and dry weights significantly increased at 200mM NaCl salinity compared with the control or the 400mM NaCl level. Root dry weights at both 200mM and 400mM NaCl salinity levels were significantly higher than the control.

Rapid blight is a new disease of cool season turfgrasses caused by Labyrinthula terrestris. Disease often occurs on turf irrigated with high salinity water and in areas of frequent mowing. The effects of salinity of irrigation water on symptom development were studied in the laboratory using two-week-old seedlings of perennial rye "Brightstar SLT. " Irrigation water was adjusted to 0.5, 0.8, 1.4, 1.8, 2.0, 2.3, 2.8, 4.0, 6.0 and 8.0 dS/m by adding artificial seawater. Plants were inoculated with a 2x10⁵ cells/ml suspension of Labyrinthula terrestris isolated from diseased turf in Arizona. Plants were infected, but not symptomatic, when irrigated with 0.5 dS/m water. At salinities from 0.8 to 8.0 dS/m, symptom development increased as salinity increased. These findings substantiate field observations that rapid blight becomes increasingly more severe as salinity of irrigation water increases.

Kentucky bluegrass (Poa pratensis L.), cv. Nu Star was studied in a greenhouse to evaluate its growth responses in terms of shoot length and dry weight under NaCl (sodium chloride) salinity and different levels of Trinexapac-ethyl( primo Max). Plants were grown hydroponically under control and one level of salinity [EC (electrical conductivity) of 5 dS/m] and three levels of primo Max (0.3, 0.6, and 0.9 oz/1000 ft²), using Hoagland solution No. 1. Plant shoots (clippings) were harvested weekly, oven dried at 60 oC, and dry weights recorded. At each harvest, shoot length was measured and recorded, percent visual canopy green cover was also estimated. The results show that shoot length and shoot dry weight (DW) of Kentucky bluegrass significantly decreased with both salinity and primo treatments, although the differences in shoot length and shoot DW were not significant between primo treatments at 0.6 and 0.9 oz/1000 ft² application rates. The green coverage of the turf canopy decreased under salinity stress, and the reduction of green canopy coverage by salinity was more pronounced when turf was treated by primo, suggesting that primo significantly reduced the salt tolerance of Kentucky bluegrass. The above results were observed for both cumulative as well as the weekly growth responses.

No description available.

The ET rate of bermudagrass is relatively well known. The ET rate of Seashore paspalum in an arid environment is not, nor is there any information on the ET of Distichlis as a mowed turf. A greenhouse test using gravimetric lysimeters was conducted in the late summer of 2004 to measure and compare the ET of two Distichlis clones and Sea Isle 1 seashore paspalum to that of Tifway 419 bermudagrass. This test showed that under glass house conditions when soil moisture was not limiting: (1)Seashore paspalum had a higher ET rate than A119 saltgrass in terms of mm/day, and total consumptive water use for the 19 day test period, (2) A48 saltgrass and Tifway bermudagrass had similar daily ET rates and similar total water use, (3) total water use between two select saltgrass clones was not significantly different . Saltgrass A48 and A119 had a total consumptive water use of 84.2 and 76.5 mm, respectively over the 19 day test period. Tifway Bermuda totaled 82.2 mm, and Sea Isle 1 used 92.1 mm over 19 days.

No description available.

Longline fishing is the most common elasmobranch capture method in the world, both for commercial fishing, and to a lesser extent for scientific surveys. The capture of an animal on a longline initiates a series of physiological responses designed to promote survivorship in the short term, but if unchecked, can cause reduced individual fitness and/or mortality in the long term. Given widespread declines in shark populations, an improved understanding of the physiological costs of longline capture is needed. The aim of this thesis was to investigate the physiological response of sharks to capture and restraint, to assess novel, non-invasive alternatives to scientific longline surveys, and to generate scientific insight into poorly understood elasmobranch populations in The Bahamas. The results presented herein suggest that some species of shark are able to recover from the physiological stress of capture despite the presence of persistent negative stimuli. Tonic immobility was assessed as a means of generating baseline blood chemistry data, but was found to be inappropriate given that it increases the magnitude of physiological perturbation in the short term. To avoid the stress of capture altogether, Baited Remote Underwater Video Surveys (BRUVS) were considered as a non-invasive alternative to capture based surveys, however, it was concluded that they lack the resolution necessary to answer fine scale demographic questions. For the Caribbean reef shark, longline surveys yielded high resolution data allowing the identification of fine scale spatiotemporal shifts in demographic population structure with minimal cost (mortality). Nevertheless, the ethics of using capture based surveys on sensitive species are questionable when alternative techniques are available. Deep water sharks caught on longline surveys exhibited high mortality rates, however, for these very poorly understood species moribund specimens have great scientific value which in some cases can offset the high ecological costs of the surveys. The results presented in this thesis highlight the on-going need for improved biological and ecological research into the majority of elasmobranch populations, particularly with regards to anthropogenic interactions such as capture. Given the tenuous conservation status of many species, the acquisition of applied, management focused data should remain the priority of elasmobranch scientists.