This study tested the hypotheses that 1) 28h head-down bed-rest (HDBR) would result in significant hypovolemia and cardiovascular deconditioning, and that 2) NASA’s fluid loading protocol (ingestion of 15 ml/kg water with a 1g NaCl for every 125ml of water consumed) would restore normovolemia and prevent cardiovascular deconditioning resulting from 28h HDBR. Nine healthy men were tested in 5 testing scenarios, with a progressive lower body negative pressure (LBNP) protocol performed before and after each scenario to measure the subjects’ cardiovascular responses to orthostasis. Subjects were tested in two 28h HDBR conditions, without fluid loading (NFL) and with fluid loading (FL), as well as in three 4-hour control conditions to isolate the effects of circadian rhythm, HDBR, and fluid loading. After 28h NFL HDBR, plasma volume was reduced by 8%. There were no symptoms of syncope during orthostatic testing following 28h NFL HDBR, however cardiovascular deconditioning was apparent as there were significant increases in heart rate, reductions in central venous pressure, and reductions in portal vein diameter during LBNP testing. There were no changes in stroke volume, cardiac output, systemic vasoconstriction, cardiac measures, and arterial and cardiopulmonary baroreflex responses, and no evidence of splanchnic or venous pooling. This study also found that NASA’s fluid loading protocol was ineffective at restoring normovolemia after 28h HDBR, as there were no differences in plasma volume between 28h FL HDBR post and 28h NFL HDBR post tests (p=0.22). Cardiovascular deconditioning was not prevented by fluid loading as the heart rate response remained elevated and central venous pressure remained reduced after 28h FL HDBR. In addition, four of the nine subjects experienced nausea during administration of the fluid loading protocol prescription and two subjects vomited, further evidence that NASA’s fluid loading protocol is not effective at preventing orthostatic hypotension. Investigation of control models verified that deconditioning was the result of HDBR. It was also concluded that circadian rhythm did not affect the measured cardiovascular responses and the fluid loading protocol was ineffective at increasing blood volume in the absence of HDBR.

Tanning bed use, especially among young, white females, has become a serious health problem in the United States. Those who use tanning beds value a tanned appearance; thus, one possible way to get individuals to stop using tanning beds is to persuade them to begin using an alternative method: a sunless tanner. This study sought to use persuasive messages to encourage individuals to both stop using tanning beds and start using a sunless tanner. Deviance Regulation Theory (DRT) was used to design three messages, and source expertise was manipulated (high and low). In addition, attitudes, perceived norms, benefits and threats about tanning were examined. Results indicate that the combination of DRT message design and source expertise produced several message conditions that were effective at decreasing tanning bed use intent. No combined message condition was effective at changing sunless tanner use intent. DRT message design alone did not produce results, nor did source expertise. Tanning attitudes were influenced by reference groups, and perceived norms about tanning predicted individual‘s tanning bed use for several reference groups. In addition, there was an interaction between benefits and threats of tanning.

Thesis (doctoral)--Helsinki University of Technology, 2000. / Includes bibliographical references. Also available on the World Wide Web.

No description available.

Biomass gasification is a technology under development that presents a means of generating hydrogen using renewable energy. While many forms of gasification have been investigated, steam gasification using a dual fluidised bed (DFB) reactor has been shown to efficiently produce high hydrogen content producer gas. The aims of this research were to increase the hydrogen yield from the 100kW DFB gasifier installed at the University of Canterbury, and thereby improve the current state of the art of gasifier operation. Calcium carbonate-based minerals such as calcite and dolomite were shown to be able to improve hydrogen production by absorbing carbon dioxide in the producer gas, promoting the water gas shift reaction. Bed material mixtures of olivine and calcite were the most effective at improving gasifier performance, increasing producer gas yield by 20%, increasing cold gas efficiency by 6% and increasing hydrogen yield by 85%. In addition, the carbon monoxide content was reduced and the ratio of hydrogen to carbon monoxide in the producer gas was ideal for Fisher-Tropsch synthesis of liquid fuels.

No description available.

No description available.

Spatial and temporal variations in channel morphology, near-bed velocity, shear stress, bedload transport rate, pebble tracer movement, and bedload and bed material size distribution were measured in seven different channel patterns in two gravel-bed rivers in the Scottish Highlands (the Dubhaig and Feshie) and a proglacial stream in Norway (the Lyngsdalselva). The results showed that there were discernible links between the channel processes and changes which were consistent for all river types. 169 shear stress estimates from velocity profiles with changing discharge showed that Keller's (1971) velocity-reversal hypothesis holds true in different channel patterns of gravel-bed rivers and can be extended to include subunits of the pool/riffle cycle. At discharges near bankfull there is a decrease in the flow strength and amount of bedload movement from the poolhead down to the pooltail (and then riffle). On a broader scale 72 Helley-Smith bedload samples and the movement of over 3700 pebble tracers showed that the entrainment of different size fractions from heterogeneous bed material is inefficient and is overpredicted by the traditional bedload transport equations. Empirical analyses showed that when the armour is mobile/broken large and small particles have almost equal mobility as first proposed by Parker et al. (1982) and Andrews (1983). However for the majority of flow conditions the armour is static and entrainment is selective to a greater or lesser degree depending on the availability of appropriate-sized sediment at the surface and from bank erosion. The magnitude and direction of flow strength and bedload transport helps to explain the location and mode of channel development as revealed by repeated levelling and mapping. The accelerating convergent/decelerating divergent cells of flow alter the channel morphology in predictable ways. The positions of these cells can change with increasing discharge as the channel becomes generally, rather than locally, competent to move coarse sediment. The rates of bank erosion and volumetric scour and fill decreased from the active multi-braided system through to the stable straight channel type.

Hydrotreating is the response to the necessity of a cleaner feed for downstream processes and reduced pollution. Hydrotreating catalysts are vital in this process; hence catalyst deactivation is a key issue. The principal objective of this research was the experimental study of hydrotreating catalyst deactivation due to arsenic compounds. The hydrotreating of light gas oil, in the presence and absence of an arsenic compound over a commercial NiMoS catalyst, was investigated in a trickle bed reactor (temperature 315-360˚C, space velocity = 1-3 h-1, pressure = 3MPa). Kinetics of first order for nitrogen and sulphur were found and activation energies values of 32 kj/mol and 76 kj/mol respectively. Studies of activity changes, suggested that arsenic mainly affects the conversion of sulfur compounds; which might indicate that arsenic prefers mainly the S edge of the catalysts. Activation energy values decreased after arsenic introduction, which may suggest pore plugging of the catalyst. / Chemical Engineering

Thesis (M.S.)--Ohio University, November, 1982. / Title from PDF t.p.