Thesis--John Hopkins Univ. / Vita. Bibliography: leaves 45-46.

Thesis (M.S.)--Brigham Young University. Dept. of Physics and Astronomy, 2005. / Includes bibliographical references (p. 45-46).

Thesis (PhD)-Open University. BLDSC no.DXN020071.

Thesis (Ph. D.)--Baylor University, 2006. / Includes bibliographical references (p. 230-241).

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abstract: The existing compact models can reproduce the characteristics of MOSFETs in the temperature range of -40oC to 125oC. Some applications require circuits to operate over a wide temperature range consisting of temperatures below the specified range of existing compact models, requiring wide temperature range compact models for the design of such circuits. In order to develop wide temperature range compact models, fourteen different geometries of n-channel and p-channel MOSFETs manufactured in a 0.18μm mixed-signal process were electrically characterized over a temperature range of 40 K to 298 K. Electrical characterization included ID-VG and ID-VD under different drain, body and gate biases respectively. The effects of low-temperature operation on the performance of 0.18μm MOSFETs have been studied and discussed in terms of sub-threshold characteristics, threshold voltage, the effect of the body bias and linearity of the device. As it is well understood, the subthreshold slope, the threshold voltage, drive currents of the MOSFETs increase when the temperature of the MOSFETs is lowered, which makes it advantageous to operate the MOSFETs at low-temperatures. However the internal linearity gm1/gm3 of the MOSFETs degrades as the temperature of the MOSFETs is lowered, and the performance of the MOSFETs can be affected by the interface traps that exist in higher density close to conduction band and valence band energy levels, as the Fermi-level moves closer to bandgap edges when MOSFETs are operated at cryogenic temperatures. / Dissertation/Thesis / M.S. Electrical Engineering 2010

Thesis (Masters Diploma (Technology)--Cape Technikon, Cape Town,1992 / This research project involved the design, development and manufacture of a krypton gas target system for the production of the radioisotope Rubidium-81 at the National Accelerator Centre (NAC). The newly designed system had to be linked to the existing production facilities, which set certain restraints and fIxed parameters to the design approach. The highl'ressure krypton-filled gas target was designed to link up to the existing transport system which is used for the transportation of all targets to and from the target bombardment station and· the hot-cells where processing takes place. Radiation resistant materials had to be selected for the target, as it would be exposed to high radiation doses during bombardment in the target bombardment station. Target cooling aspects also had to be taken into consideration due to the heat generated during bombardment. A cryopump system for transferring the krypton gas from a gas storage reservoir to the gas target and back during loading and unloading was developed. A further development was a system which would retrieve the formed radioisotopes in a water suspension after bombardment. This demanded the design of a set of spray nozzles which were mounted inside the gas target chamber, a suitable water circulating pump and ruters to trap the suspended radioisotopes. Due to the high radiation levels] which are, of course, dangerous to operating personnel, the whole system was constructed inside a hot-cell, and thus required the design of a fully remote control system together with gas monitoring and safety components. The processing system itself required many switching and monitoring opera.tions which ha.ve to be carried out accurately and sequentially and this further demanded making use of a microcomputer control system. Material strengths, manufacturing methods, performance and selection of the VarIOus components in the system were investigated, as well as the respective routine maintenance and repair aspects.

The woodlice, Porcellio scaber (Latreille, 1804), is a terrestrial isopod. Its metabolic reserves and body size are important factors affecting the fitness attributes, such as survival at unfavourable conditions. The larger and heavier individuals did not survive longer than smaller individuals. Amount of glycogen and body weight (fresh and dry) appeared to be an inapplicable parameter in the observed differences among individuals during survival at low temperature. We compared three treatments (long day, short day, natural autumn conditions) of Porcellio scaber and found differences in amount of energy reserves and cryoprotectants.

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It is impossible to enumerate all the areas where diffusion plays a crucial role. Numerous studies of diffusion have been made since the observation of brownian motion by Robert Brown in 1827. In the last decades, the development of computers made it possible to carry numerical studies of diffusion. Monte Carlo algorithms are often used to model the random walk of a particle in a given system in order to measure its diffusion coefficient. In the last years, Dr Slater's research group developed an exact calculation method that allows one to compute diffusion coefficients with high precision. This calculation method, even if major modifications were necessary, is the base of the two projects presented in this thesis. The first project is a sequel of an article published in 2006 by Hickey et al. These authors derived an expression that predicts the diffusion coefficient of a point-like particle in a two-phase system, such as a hydrogel made of gelatin with maltodextrin viscous inclusions. This expression works well for a simple two-phase system but neglects numerous characteristics such hydrogels can present. In this thesis' first project, we modify this expression in order to include the possible interactions between the particle and the gel structure, the interfacial steric effects between phases and the possible incomplete phase separation. We validate these modifications by comparing them with exact numerical calculations. In preceding studies made by the research group of Dr Slater, it was assumed that the system was quenched, i.e. the obstacles didn't move. However, it is logical to believe that gel fibers inside a real hydrogel are subject to thermal motion and that they vibrate around a mean position. The second project presents a new numerical method allowing one to investigate the effect of obstacles motion on the diffusion of a particle. We vary different parameters such as the vibration frequency compared to the diffusion time scale of the particle, the amplitude of vibration, the obstacle concentration as well as their configuration (periodic or random). This new method is innovative because it makes it possible to study in details the transition of a system from a quenched state (fixed obstacles) to an annealed state (obstacles vibrating much faster than the diffusion time scale of the particle).