This study's purpose was to determine the validity of near-infrared interactance (NIR) and bioelectric impedance (BIA) in tracking changes in body composition over 12 wk of either a high intensity endurance (ET) or resistance (RT) training program in nondieting weight-stable untrained males. Prior to and following the control or training period, each subject completed a series of body composition analyses including hydrostatic weighing (HW) with a measurement of residual volume; anthropometric measurements including height, weight, skinfold, and girth; BIA measurement; and NIR measurements. Based on the HW results, there were no significant body composition changes in the control group. For the ET group, a significant decline in relative body fat resulted from a reduction in fat weight (FW) with no change in fat-free weight (FFW). In the RT group, both a significant decline in FW and an increase in FFW contributed to this group's decline in relative body fat. Tracking changes in relative body fat, FW, and FFW, skinfolds agreed reasonably well with HW in all groups while BIA and NIR did not always track body composition changes well. For example, SF and BIA were significantly correlated with the changes in FFW (HW = + 4.1%, SF = + 4.5%, BIA = + 3.1% NIR = - 0.7%) observed in the RT group compared to HW (SF: r-value = 0.45, SEE = 2.5; BIA; r = 0.33, SEE = 3.4) while the NIR measurements were nonsignificant (r = 0.09, SEE = 5.0). Interestingly, NIR underestimated the gain in FFW in the resistance trained group while BIA underestimated the changes in relative body fat, FW, and FFW in the endurance trained group. Based on these results, BIA aim NIR appear not to be appropriate measurement tools for tracking body composition changes in endurance and resistance training individuals respectively.

Accelerated Life Testing (ALT) is an effective method of demonstrating and improving product reliability in applications where the products are expected to perform for a long period of time. ALT accelerates a given failure mode by testing at amplified stress level(s) in excess of operational limits. Statistical analysis (parameter estimation) is then performed on the data, based on an acceleration model to make life predictions at use level. The acceleration model thus forms the basis of accelerated life testing methodology. Well established accelerated models such as the Arrhenius model and the Inverse Power Law (IPL) model exist for key stresses such as temperature and voltage. But there are other stresses like subsea pressure, where there is no clear model of choice. This research proposes a pressure-life (acceleration) model for the first time for life prediction under subsea pressure for key mechanical/physical failure mechanisms. Three independent accelerated tests were conducted and their results analyzed to identify the best model for the pressure-life relationship. The testing included material tests in standard coupons to investigate the effect of subsea pressure on key physical, mechanical, and electrical properties. Tests were also conducted at the component level on critical components that function as a pressure barrier. By comparing the likelihood values of multiple reasonable candidate models for the individual tests, the exponential model was identified as a good model for the pressure-life relationship. In addition to consistently providing good fit among the three tests, the exponential model was also consistent with field data (validation with over 10 years of field data) and demonstrated several characteristics that enable robust life predictions in a variety iv of scenarios. In addition the research also used the process of Bayesian analysis to incorporate prior information from field and test data to bolster the results and increase the confidence in the predictions from the proposed model.

The purpose of this investigation was to determine the effects of a four day creatine load and simultaneous energy restriction on muscle creatine content, exercise performance, and body composition in 24 male recreational resistance trainers, age 18-26. Sixteen subjects were randomly divided into placebo (Pl, n=8) and creatine supplement (CrS, n=8) groups. Control (C, n=8) subjects of the same age were recruited separately g à d-1 to complete the performance and body composition tests while consuming their normal diet. The CrS group was administered 20 g à d-1 of creatine monohydrate (Cr) mixed with 5 g à d-1 of sucrose, while the Pl group was administered 25 of sucrose. Both CrS and Pl consumed a formula diet of 75.3 kJ (18 kcal) à kg-1 à d-1 for 4 d. Testing before and after energy restriction consisted of a repeated sprint cycle performance test (10 sprints of 6s, with 30s rest), hydrostatic weighing, and resting needle muscle biopsy. Testing revealed that subjects in CrS and Pl demonstrated significant decreases in body weight and % body fat (%BF) with no difference between groups. However, Pl demonstrated a significantly greater % loss in FFM (2.4 ± 0.25%) compared to CrS (1.4 ± 0.4%) (p<0.05). The muscle fuel stores of CrS and Pl responded significantly to the diet. Significant increases in muscle total Cr (p<0.01), free Cr (p<0.01), and CrP (p<0.05) of 16.5%, 16.8%, and 16% respectively were demonstrated by CrS over the energy restriction period, while Pl demonstrated significant decreases of 7.2% and 8.2% respectively in muscle total Cr (p<0.01) and free Cr (p<0.05). There were no significant differences between groups for performance during the cycle test, however, there were trends toward group by time interactions for performance enhancement in CrS relative to Pl, as total work (p=0.078) and work capacity (p=0.058) increased 3.8 ± 2.2% in CrS and decreased 0.5 ± 0.4% in Pl. It was concluded that short-term energy restriction resulted in decreased muscle Cr storage, and that Cr supplementation during energy restriction increased muscle Cr and CrP stores. Consumption of Cr allowed CrS to lose a significantly lower % FFM compared to Pl. Cr supplementation resulted in trends toward improved performance in CrS relative to Pl after energy restriction, but did not influence losses in body weight or %BF. / Master of Science

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This research examines the role of actin cytoskeleton filaments in chondroinduction by cyclic hydrostatic pressurization. A chondroinductive hydrostatic pressurization system was developed and characterized. A pressure of 5 MPa at 1 Hz frequency, applied for 7200 cycles (4 hours intermittent) per day, induced chondrogenic differentiation in C3H10T1/2 cells while 1800 cycles (1 hour intermittent) did not induce chondrogenesis. Quantitative analysis of chondrogenesis was determined as sulfated glycosaminoglycan synthesis and rate of collagen synthesis while qualitative analysis was obtained as Alcian Blue staining and collagen type II immunostaining. Actin disruption using 2 uM Cytochalasin D inhibited the enhanced sGAG synthesis in the chondroinductive hydrostatic pressurization environment and significantly inhibited rate of collagen synthesis to the mean level lower than that of the non-pressurized group. These results suggest an involvement of actin cytoskeleton filaments in mechanotransduction of cyclic hydrostatic pressure.

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The influence of layer waviness in thick cross-ply composite cylinders subjected to hydrostatic pressure is investigated. The cylinders considered are graphite-epoxy with a 2: 1 ratio of circumferential to axial layers. All cylinders considered contain 104 total layers with a layup of [90/(90/0/90h71s, where a '0° 1 layer is taken to be in the axial direction. The influence of a single isolated group of wavy layers in an otherwise perfect cylinder is evaluated. Layer waviness in only the circumferential direction is considered, and the analysis is assumed to be valid only away from the cylinder ends. A parametric investigation is performed to determine the combined influence of wave location, wave amplitude, and cylinder geometry on hydrostatic response of the cylinder, particularly the stresses generated in and around the wave. The wave is assumed to be located either at the inner or the outer radius of the cylinder. Three wave amplitudes, 0, are considered: 1/2, 1, and 2 layer thicknesses. Only waves with a half wave length of 10 layer thicknesses are considered. Three cylinder geometries are considered, specifically ones with radius to thickness ratios of 5, 10, and 20. Finite element analysis is used to determine the stress state within the imperfect, i.e., wave included, cylinders. Based on a maximum stress failure criterion, failure pressures are determined for each of the various wave and cylinder geometries. Failure pressures for the imperfect cylinders are compared with those for a perfect cylinder to determine the failure pressure reduction ratios due to fiber waviness. It is shown that pressure capacity reductions of approximately 50% are possible for the range of parameters studied. Failure is primarily due to fiber compression, though interlaminar shear and interlaminar tension are a factor. Finite element analysis is also used to deter ine the failure pressure of the perfect cylinder due to buckling. This is done to determine whether failure due to buckling may overshadow material failure due to fiber waviness. It is shown that buckling is a factor in only one of the cylinder geometries considered, and only in the cases of mild layer waviness. In addition to results, details about the finite element model are presented. These details include geometry of the wave, changes in material properties due to local fiber rotation and local volume fraction changes, boundary conditions, and justifications for modeling simplifications that were made in an effort to reduce computational costs and analysis times. / Master of Science