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.

The primary objective of this thesis was to test the material properties of the new Grade 300, low-relaxation prestressing strand. The purpose of this testing was to verify the advertised breaking strengths and relaxation properties of the Grade 300 strand. Additional properties, such as yield strength, modulus of elasticity, and elongation, were also examined. Several tests were performed on each specific type of strand. For example, six tension and eight relaxation tests were performed on the Grade 300, 0.5 in. diameter, 0.153 square in. area strand. From the tests, it is concluded that the advertised breaking strengths and relaxation properties from Strand-Tech Martin, Inc. were accurate and meet the industry standards for low relaxation strand. The secondary objective of this project was to comment on the benefits of the Grade 300 strand as it pertains to the bridge industry. It was concluded from the tests that the Grade 300 strand had a 10 per cent larger 1 per cent elongation stress compared to the bridge industry standard Grade 270 strand. Furthermore, the amount of loss due to relaxation for the Grade 300 strand was comparative to that of the Grade 270 strand. While additional testing needs to be done to include stress-corrosion, transfer length, development length, and flexural strength, the completed testing indicates that less strand will be required using Grade 300 strand versus Grade 270 strand to achieve a set span length and transverse girder spacing. In addition, with the industry gradually progressing toward using higher strength concretes, longer span lengths and larger transverse girder spacing can be achieved by using the Grade 300 higher strength strand. The final objective of this testing was to examine the procedures and testing methods outlined by ASTM A416, Standard Specification for Steel Strand, Uncoated Seven-Wire for Prestressed Concrete (2005), ASTM E328, Standard Test Methods for Stress Relaxation for Materials and Structures (2002), and ASTM A370, Standard Test Methods and Definitions for Mechanical Testing of Steel Products (2005). The breaking strength and yield strength tables in ASTM A416 (2005) need to be updated with the new Grade 300 strand information. Based on this testing, ASTM should also remove the recommendation of simply using aluminum foil and Standard V-Grips to grip the strand. Even though the standard Grade 270 and Grade 300 regular diameter strand met the material property requirements when using aluminum foil as a cushioning material, none of these samples broke clearly within the gage length of the strand. Furthermore, all of the super area strand samples failed prematurely at the grips due to the notching effect of the V-grip teeth. Thus, an alternative method involving aluminum tubing, aluminum oxide, and epoxy were used to create a cushioning device between the V-grip and the strand in order to achieve the true ultimate breaking stress of the strand. Finally, ASTM should comment on the impact of test length on the total relaxation measurements. Three test lengths were evaluated during the 26 relaxation tests. As the test length increased, the total measured relaxation decreased. Losses due to chuck slip and frame settlement were negligible as the strand test length increased. / Master of Science