published_or_final_version / abstract / Electrical and Electronic Engineering / Master / Master of Philosophy

published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

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No description available.

The object of this thesis was to investigate the role of two different harvest protocols on the post mortem physiology of Chinook salmon, and associated deteriorative processes that occur during frozen storage of the white muscle tissue. The two different harvest methods employed, termed 'rested' and 'exercised', were selected because of the contrasting levels of activity of the animal prior to, and upon, slaughter. While the latter represents conventional harvest techniques Rested and exercised harvesting protocols produced tissue in significantly different physiological states. Immediately post harvest, rested tissue maintained high metabolic energy stores of ATP and glycogen within the tissue, with low concentrations of tissue and plasma lactate. Exercised tissue exhibited near depleted concentrations of ATP and glycogen and a marked metabolic acidosis and lactate accumulation. When frozen immediately post harvest, rested white muscle tissue stored at -19℃ showed no significant changes in these metabolite concentrations over a six month period of profiling. However, during storage of rested tissue at -9℃, hydrolysis of ATP and glycogen with no coincident increase in lactate was observed. No significant changes in metabolite levels were observed within exercised tissue stored at -19 and -9℃, owing to the lack of metabolic energy stores. Transfer of tissue from frozen (-80 and -19℃) to chilled (-1 and +4℃) temperatures witnessed a rapid depletion of tissue ATP and glycogen stores, with rapid increases in tissue lactate concentrations. This metabolic activity was more significant in rested tissue owing to the larger concentrations of metabolic energy stores. This metabolic activity was identified to occur between the temperatures of -3 and -1.5℃ and occurred abruptly (i.e. ATP concentrations depleting in less than one hour) in time. During frozen storage (-19℃ and -9℃), harvest treatment had no significant effect on lipid oxidation processes. However, rested tissue showed a significant ability to retard lipid oxidation processes once removed from frozen storage and placed at chilled temperatures. Throughout six months storage at -19℃ storage, harvest treatment had a significant effect on the rate of protein denaturation as rested tissue consistently held higher concentrations of soluble protein over the storage period. No significant effect was observed between treatments in the rate of protein denaturation during one month frozen (-19℃) then chilled (+4℃) storage. In a supplementary frozen (-80℃) then chilled (-1℃) storage experiment, post mortem storage of rested, whole fish, at chilled (+5℃) temperatures prior to white muscle excision and freezing, was compared to rested and exercised tissue in which the white muscle had been excised and then frozen immediately post harvest. In this experiment rested tissue exposed to a 6 or 24 hour post mortem chilled storage period demonstrated significant retardation of lipid oxidation processes when compared to rested white muscle tissue that was excised and frozen immediately post harvest. Further comparison of the six and 24 hour post mortem stored tissue showed a significant increase in lipid oxidation products after 21 and 24 days chilled storage, respectively. Comparison of results from the six and 24 hour post mortem storage experiment were bordering on significance (p=0.083), warranting further investigation on the effect of post mortem storage of rested tissue on lipid oxidation processes.

An investigation into the flux of soil water under the influence of a thermal gradient was conducted in closed soil systems in the laboratory. A thermal gradient was imposed across the sandy loam soil columns and measured continuously for the duration of the experiment. The movement of soil water was monitored periodically using a gamna ray attenuation device until the columns reached an apparent steady state condition with no net flow. Imposition of boundary conditions enabled delineation and evaluation of the system parameters. Values of net water flux in soil columns were analyzed using the Taylor-Cary irreversible thermodynamic and the Philip-de Vries theory of water movement. Application of the Taylor-Cary equation to describe the flow reveals that for initial time periods the flow is slightly overestimated, however, this small difference may be within the realm of experimental error. The flow predicted by the Taylor-Cary equation for the succeeding time periods greatly exceeded the measured flow rates. The Philip-de Vries theory of soil-water movement predicted greater net water movement than was observed in soil columns with a temperature gradient of 2.67 ° C/cm and with an average soil water content of 10.5 to 11.5 cm³/cm³. The following conclusions were reached after analyzing the data for the sandy loam soil material. Water content and temperature influence the diffusion transfer coefficient, β*, in a closed soil system. Thus the transfer coefficient is not an independent entity. Hysteresis is present in the wetter part of the system, although the magnitude of hysteresis involved is unknown. The β* coefficient can be evaluated only in regions where hysteresis is not present. The transfer of soil water was greater in a leached soil with no air gap than in an unleached soil with no air gap. There was supporting evidence that liquid water continuity did not exist throughout the column since there was no appreciable solute transport. The observed change in soil water content distribution at 18.0 cm³/cm³ to the imposed temperature gradient was not significant for the sandy loam soil material. The observed soil water flux increased in response to the imposed temperature gradient as soil water content decreased from 18.0 to 10.5 cm³/cm³. No analytical procedure is presently available that will describe thermally induced flow under all conditions. The approach of Philip and de Vries requires that the physical properties of the soil must be known accurately so that correct estimates can be made of the individual diffusivities. This approach has been found to predict the flow with some success on relatively dry soils, however, it possibly would be in error when estimating thermally induced flow in regions where liquid continuity exists and up through to a saturated system. The Taylor and Cary equation may be adequate for describing water flow to predict trends or obtain comparative values, however, much additional work needs to be done before it will adequately describe the flow for transient conditions or steady state conditions where nonuniform water content distributions are present.

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No description available.

No description available.

During hyperthermia therapy it is desirable to know the entire temperature field in the treatment region. Tikhonov regularization of order zero has been implemented. The accuracy of the estimates depends upon the value of regularization parameter, which has an optimal value that is dependent on the perfusion pattern and magnitude. The transient power-off time sampling length (i.e. the amount of transient data used) influences the accuracy of the estimates, and an optimal sampling length exists. The effects of additive noise are investigated, as are the effects of the initial guess of the perfusion values, and the effect of both symmetric and asymmetric blood perfusion patterns. The asymmetric patterns with noisy data are the most difficult cases to evaluate. The cases studied are not a comprehensive set, but a representative set whose results continue to show the feasibility of using state and parameter estimation methods to reconstruct the entire temperature field. (Abstract shortened with permission of author.)