The main hypothesis of this thesis was that the regulation of oxygen uptake (VO2) kinetics at the onset of exercise in trained young men is linked to cardiovascular adaptations. Two studies were conducted to investigate the interrelationships between oxygen (O2) transport and O2 utilization in accelerating VO2 kinetics at the onset of exercise. In the first study, simultaneous kinetics of VO2 and cardiac output (Q) were studied during the transition to heavy and moderate cycling exercise (Chapter 2). The acceleration of VO2 kinetics during the heavy exercise that followed prior moderate or heavy exercise was enabled by the rapid increase in Q; whereas, the acceleration of VO2 kinetics during moderate exercise that followed a heavy warm-up was associated with small changes in Q kinetics. The objective of the second study was to determine, in a model of forearm exercise, if the elevation of forearm blood flow (FBF) prior to the onset of exercise by prior circulatory occlusion would accelerate FBF and muscle oxygen uptake (VO2mus)kinetics during subsequent exercise as demonstrated previously for prior exercise (Chapter 3). Prolonged ischemia (15 min occlusion) followed by 3 min recovery reduced FBF and impaired VO2mus kinetics during subsequent heavy hand-grip exercise. However, prior heavy exercise confirmed the previous findings and resulted in a faster FBF and VO2mus kinetics. There was a high positive correlation between the time course of change in FBF and VO2mus at the onset heavy exercise. In a follow up of the second study, to investigate a possible mechanism for the slower adaptation of VO2mus following ischemia, the prior occlusion condition was repeated after ingesting a high dose of ibuprofen. Prostaglandin inhibition by ibuprofen augmented the FBF response during reactive hyperaemia and restored FBF during the heavy exercise that followed 15 min of circulatory occlusion to the control level. These two studies provide evidence that O2 delivery plays a dominant role in accelerating VO2 kinetics at the onset of heavy exercise in trained young men. The findings exposed differences in the mechanisms regulating pulmonary VO2 and VO2mus with prior exercise resulting in higher Q and FBF, but no changes in O2 extraction to yield the faster increase in pulmonary VO2 and VO2 at the onset of subsequent heavy exercise. In contrast, prior occlusion slightly retarded the increase in FBF and significantly reduced O2 extraction thus delaying VO2 kinetics. The precise mechanisms impairing VO2mus kinetics at the onset of heavy forearm hand-grip exercise that starts after a brief recovery from prolonged occlusion are still unknown, but this impairment may be partially due to a vasoconstrictor effect restricting blood flow during the adaptation to exercise and redistribution of the blood to the periphery. In a third study, the influence of muscle activity on the VO2 slow component during heavy exercise and O2 cost during moderate exercise that followed a heavy warm-up were examined (Chapter 4). The heavy exercise VO2 slow component was attenuated in a graded fashion by prior moderate and heavy warm-ups, and the principal components analysis showed a moderate but significant correlation between the changes in the integrated electromyographic activity and the VO2 slow component amplitude. The higher O2 cost of moderate exercise following a heavy warm-up was associated with higher mean power frequency. Changes in VO2 slow component and increased O2 cost during moderate exercise after prior heavy warm-up appear to be related to some changes in surface electromyographic activity which may provide some evidence for increased muscle fibres recruitment.

The purpose of this study was to compare physiological variables (i.e. oxygen consumption, blood lactate, heart rate, respiratory exchange ratio) during exercise on a double poling ergometer modified for sit skiers to a field test for the same skiers. Three male and four female athletes from the Canadian National / Developmental team (17-54 years of age, ranging in ability from a complete T7 spinal injury to cerebral palsy) completed a field test and a double poling ergometer protocol separated by at least 24 hours. Both protocols consisted of three maximal sets of skiing of three minutes duration per set separated by approximately one and a half minutes rest. A wireless metabolic system (Sensormedics, VmaxST or Cosmed, K4b2) and heart rate monitor were used to measure physiological responses during each test. Arterialized blood lactate was measured before and after each set and for 15 minutes post exercise. There were no significant differences between the field and ergometer tests for peak oxygen consumption (VO2 peak) (field=35±6 mL/kg/min vs. ergometer=33±7 mL/kg/min; p=0.491). However, significantly higher peak heart rate (field=173±5 bpm vs. ergometer=178±4 bpm; p=0.046) and respiratory exchange ratio (RER) (field=1.2±0.1 vs. ergometer=1.4±0.1; p=0.022) were found during the double poling ergometer protocol. There were no significant differences in blood lactate at baseline and after set one between protocols. However, a significantly higher lactate was found after set two (field=7±4 mmol/L vs. ergometer=12±5 mmol/L; p<0.001) and set three (field=8±3 mmol/L vs. ergometer=13±4 mmol/L; p=0.001) during the ergometer protocol compared to the field test. There were moderate correlations between the field and double poling ergometer for VO2 peak (r=0.79; p=0.035), and peak blood lactate (r=0.83; p=0.02). However, no correlations were found between protocols for peak heart rate (r=0.37; p=0.491) and RER (r=0.54; p=0.207). Results of this study suggest that the double poling ergometer is similar to a field test for evaluating VO2 peak in elite cross country sit skiing athletes; however, the ergometer test involves a higher heart rate and anaerobic component.

Probing Defects and Electronic Processes on Gadolinia-doped Ceria Surfaces Using Electron Stimulated Desorption Haiyan Chen 133 Pages Directed by Professor Thomas M. Orlando Polycrystalline gadolinia-doped ceria (GDC) has been widely investigated as a promising low temperature solid oxide fuel cell (SOFC) electrolyte and as part of composite electrodes. In this thesis, electron stimulated desorption (ESD) has been used to probe the defect related electronic properties of GDC surfaces and the interactions of water and molecular oxygen with these surfaces. In particular, the electron irradiation induced surface charging of GDC has been found to be dependent on the incident electron energy: negative at lower energy and positive at higher energy. Trapping of electrons and holes by the gadolinium aggregated, oxygen vacancy rich grain boundaries has been considered as the origin of surface charging. Depending on the sample treatment, there can be various defects, hydroxyl groups, chemically adsorbed water molecules, or water dimers on GDC surfaces. Water and molecular oxygen interact primarily with defect sites. Systematic investigations of electron stimulated O+ desorption have yielded activation energies relevant to oxygen vacancy production on ceria surfaces, and to surface positive charge dissipation related to ionic conduction of GDC. Highly efficient electron stimulated O+ desorption from GDC surfaces has been attributed to the lowered charge density on oxygen ions coordinated with oxygen vacancy clusters and thus may be used as a probe for surface defect types. Electron stimulated desorption of O2+ from GDC surfaces during molecular oxygen adsorption has shown the ability of ESD to detect chemically adsorbed O2. The velocity distributions of O2+ can be used to probe intermediate adsorption species such as O2, as well as the positive charge of the surface. Overall, this thesis has demonstrated that ESD can provide important information on the kinetics and dynamics of surface charging, charge transport, adsorption and reactions occurring at defective insulating metal oxides materials. The abilities to probe the defects and their roles in surface processes make ESD a valuable technique for surface chemistry and catalysis studies.

Three stalagmites, JSD 01, JSD 02, and L12, were collected from Libo county in the southern Guizhou provence. JSD 01 and JSD 02 are 14cm long stalagmites from Golden Lion Cave and L12 is a 7.1cm long stalagmite from Dragon Spring Cave. Subsamples were drilled along the central axis for JSD 01V while subsamples of JSD 01H were obtained along the horizontal axis. Subsamples were analyzed for carbon and oxygen stable isotopes. The age determination for stalagmites were done by U-Th dating. The JSD 01 dates range from 93,700 to 95,200 yr B.P.; the JSD 02 dates are from 87,900 to 88,200 yr B.P.. The L12 dates are from 750 to 9,560 yr B.P.. The stalagmite record from Golden Lion Cave is correspondent to the marine isotope stage 5 (MIS 5) in age. The £_18O values of stalagmite JSD 01 record in MIS 5c are ranging from -6.58‰ to -5.17‰ ; £_13C values are from -9.19‰ to -6.84‰. Stalagmite JSD 01H records are ranging from -8.11‰ to -5.7‰ for £_18O and from -9.67‰ to -2.46‰ for £_13C. The £_18O values for stalagmite JSD 02 record in MIS 5c are from -8.15‰ to -7.12 ‰ and are from -9.09‰ to -5.19‰ for £_13C. The results indicate a warm and wet climate prevailing during MIS 5c and MIS 5b in Guizhou. An intensification of summer mosoon would increase in precipitation and vegetation above the cave. Result from JSD record shows data obtained from the horizontal axis may be younger in age than vertical axis in terms of sampling direction. The stalagmite L12 contains two sections: (1) Dates range from 700 to 2,400 yr B.P. between top and 35mm: the £_18O values are ranging from -8.23‰ to -7.07‰ while £_13C values are ranging from -11.61‰ to -6.98 ‰; (2) The £_18O values are ranging from -10.52‰ to -7.54‰ and £_13C values are from -10.75‰ to -6.98‰ between 35mm and 71mm. Results suggest a warm and wet climate prevailing during 9,000-9,600, with lighter £_18O values reflecting a strong summer monsoon. A decline of summer monsoon occurred around 9,000 yr B.P. as shown by a sharp increase in the £_18O. This sudden climatic change might lead to a decrease in vegetation and soil loss above the cave, resulting in the cease growth of the stalagmite. Around 2,400 yr B.P. the growth of stalagmite was resumed. The lighter £_13C values and heavier £_18O values represent a cooler and drier climate in late Holocene. After ~1,000 yr BP, a deforestation event occurred in the area probably which was induced by human activity.

Thesis (M. Med. Sc.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 61-66).

Thesis (Ph. D.)--Case Western Reserve University, 2009. / [School of Medicine] Department of Biomedical Engineering. Includes bibliographical references.

Thesis (M.S.)--University of Wyoming, 2008. / Title from PDF title page (viewed on Jan. 19, 2010). Includes bibliographical references.

Thesis (M.S.)--Brigham Young University. Dept. of Physical Education, 2004. / Includes bibliographical references.

Thesis (M.S.)--East Carolina University, 2009. / Presented to the faculty of the Department of Exercise and Sport Science. Advisor: Timothy P. Gavin. Title from PDF t.p. (viewed June 4, 2010). Includes bibliographical references.

Thesis (M.S.)--Ohio State University, 1955. / Includes bibliographical references (leaves 72-73). Available online via OhioLINK's ETD Center.