M.A. / While some studies have found reciprocity between migraine and temperament other studies have found that temperament does not play a role in migraine. Research results regarding the relationship between migraine and temperament are therefore contradictory. The motivation for the present study is based on the various contradictions and methodological problems of these studies. The aim is to ascertain if there are statistically significant differences between three groups of subjects namely: 1. Clients with Frequent Migraine (N=10) 2. Clients with Less Frequent Migraine (N=10) 3. Healthy Subjects (N=10) regarding a number of temperament dimensions, specifically: 1. The five subscales of the NEO PI-R (Costa & McCrae) • Neuroticism • Extraversion • Openness • Agreeableness • Conscientiousness 2. The four subscales of the Sensation Seeking Scale (Zuckerman, 1979) • Thrill and Adventure Seeking • Experience Seeking • Disinhibition • Boredom Susceptibility 3. The three subscales of the Pavlovian Temperament Survey (1992) • Strength of Excitation • Strength of Inhibition • Mobility of Nervous Processes 4. The two subscales of the IPAT Anxiety Scale (Cattell, Scheier, & Madge, 1995) • Overt Anxiety • Covert Anxiety The general aim of the present study is to provide substantial research data on the specific theory of temperament and its role in migraine. The theories of Pavlov, Eysenck, Strelau, and Zuckerman offer a theoretical framework for the conceptualisation of temperament. There are indications that certain temperament traits such as, neuroticism, extraversion, anxiety, Type A behaviour, and depression are associated with migraine (Arena, Andrasik & Blanchard, 1985; Rappaport, McAnulty & Brandtley, 1988; Rangaswami, 1983). In contrast to the above studies there are also studies which could not establish a link between migraine and certain temperament traits (Blaszczynski, 1984; Hundleby & Loucks, 1985; Schmidt, Faye, Carney & Fitzsimmons, 1987). Psychology students at the Rand Afrikaans University were chosen as a target group. The subjects had to complete a biographical questionnaire to establish whether they suffered from migraine. From an original group of 122, 30 subjects who met the criteria were selected. These subjects were then divided into three groups namely, Group 1 (Frequent Migraine), Group 2 (Less Frequent Migraine), and Group 3 (Healthy Subjects). The groups were then asked to complete four questionnaires, namely, the NEO PI-R (Costa & McCrae, 1992), the Sensation Seeking Scale (Zuckerman, 1979), the Pavlovian Temperament Survey (1992), and the IPAT Anxiety Scale (Cattell, Scheier, & Madge, 1995). Based on various studies done on the relationship between migraine and temperament, the research question can be formulated as follows. Are there significant differences in certain temperament traits between subjects suffering from frequent migraine, subjects suffering from less frequent migraine, and healthy subjects, regarding their scores on the NEO PI-R, the Sensation Seeking Scale, the Pavlovian Temperament Survey, and the IPAT Anxiety Scale. Statistical analytical techniques, including the MANOVA, ANOVA, and the Scheffe tests, were applied to establish whether there were statistically significant differences between the three groups regarding their scores on the four measuring instruments used. According to the results there were no statistically significant differences between the three groups regarding their vectors of averages on the various subscales of the four measuring instruments. The results are interpreted against the background of studies reported in the literature which also found no association between migraine and temperament. The present study is evaluated with reference to the small sample size and large number of measurements. Recommendations for future research include selecting a large test sample to enable a statistically significant distinction between the various groups. The use of other personality inventories standardised for South African subjects to test other temperament or personality traits is also recommended. Future research could possibly define groups according to other psychosomatic illnesses such as irritable bowel syndrome, ulcers, and high blood pressure and establish the possible relationship with certain temperament traits. The measuring of a wide spectrum of temperament and personality traits in order to ascertain the influence of these traits on migraine will provide more of a total picture. Also, the development of a measuring instrument for the diagnosis of migraine that will provide more valid and realistic data on the perception of migraine and also distinguish between migraine and other types of headache, would be useful.

No description available.

No description available.

Please read the abstract in the section 00front of this document / Dissertation (M Inst Agrar (Weed Science))--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted

Typescript, etc.

ZrN has been identified as a candidate material for use as an inert matrix fuel host for the transmutation of plutonium and minor actinides. These materials will be subjected to large amounts of different types of radiation within the nuclear reactor core. The types of radiation include fission fragments and alpha-particles amongst others. Recent studies suggest that nanocrystalline material may have a higher radiation tolerance than their polycrystalline and bulk counterparts. Some studies have shown that swift heavy ion irradiation may also significantly modulate hydrogen and helium behaviour in materials. This phenomenon is also of considerable practical interest for inert matrix fuel hosts, since these materials accumulate helium via (n,) reactions and will also be subjected to irradiation by fission fragments. The aim of this investigation is therefore to study the effects of fission fragment and alpha particle irradiation on nanocrystalline ZrN. In an effort to simulate the effects of fission fragments on nanocrystalline zirconium nitride different layers (on a Si substrate) of various thicknesses (0.1, 3, 10 and 20 μm) were irradiated with 167 MeV Xe, 250 MeV Kr and 695 MeV Bi ions to fluences in the range from 31012 to 2.61015 cm-2 for Xe, 1×1013 to 7.06×1013 cm-2 for Kr and 1012 to 1013 cm-2 for Bi. The purpose of this irradiation is to simulate the effects of fission fragments on nanocrystalline ZrN. In order to simulate the effects of alpha particles and the combined effects of alpha particles and fission fragments on nanocrystalline ZrN it was irradiated with 30 keV He to fluences between 1016 and 5×1016 cm-2, 167 MeV Xe to fluences between 5×1013 and 1014 cm-2 and also 695 MeV Bi to a fluence of 1.5×1013 cm-2. He/Bi and He/Xe irradiated samples were annealed at temperatures between 600 and 1000 °C. The different irradiated layers were subsequently analysed via X-ray diffraction (XRD), μ-Raman, transmission electron microscopy (TEM) and nano indentation hardness testing (NIH) techniques. XRD, TEM, μ-Raman and NIH results indicate that ZrN has a very high tolerance to the effects of high energy irradiation. The microstructure of nanocrystalline ZrN remains unaffected by electronic excitation effects even at a very high stopping power. TEM and SEM results indicated that post irradiation heat treatment induces exfoliation at a depth that corresponds to the end-of-range of 30 keV He ions. Results from He/Xe irradiated samples revealed that electronic excitation effects, due to Xe ions, suppress helium blister formation and consequently the exfoliation processes. He/Bi samples however do not show the same effects, but this is possibly due to the lower fluence of Bi ions. This suggests that nanocrystalline ZrN is prone to the formation of He blisters which may ultimately lead material failure. These effects may however be mitigated by electronic excitation effects from certain SHIs.

A series of as-grown ZnO layers have been electrically characterised by the temperature dependent (20 – 300 K) Hall-effect technique. The ZnO layers were grown by metal organic chemical vapour deposition (MOCVD) on glass substrates under various growth conditions. The temperature dependent Hall-effect technique produced mobility and carrier concentration measurements. These measurements were found to be reproducible and reliable. The carrier concentration data for the layers was fitted by the charge balance equation to accurately determine the donor level and corresponding donor concentration as well as the acceptor concentration for each sample. The measured donor levels were found to vary from sample to sample and there is evidence from the results that the variations are related to the differing growth conditions of the layers. The mobility data was also fitted to establish the dominant electron scattering mechanisms in the layers. The dominant scattering mechanisms were found to vary from sample to sample. For most of the layers studied, the dominant scattering mechanism was found to be both the ionised impurity scattering at low temperatures (20 – 100 K) and grain boundary scattering at higher temperatures (100 – 300 K). The effects of exposing the ZnO layers to hydrogen plasma were also investigated by the temperature dependent Hall-effect technique. Findings indicate that hydrogen is readily incorporated in ZnO, leading always to an increased carrier concentration. It was further noted that incorporating hydrogen into ZnO in some layers increased the mobility while in other layers it caused a decrease in the mobility. The hydrogenated samples were subsequently annealed at 600 °C for 1 hour in argon ambient resulting in the carrier concentration reducing to its original value. This effect is attributed to hydrogen diffusing out of ZnO.

In this thesis five iron phthalocyanines (FePc’s), four of which having different electron withdrawing or electron donating substituents, were evaluated as 0₂ reduction reaction (ORR) catalysts. The experimental approach simulated a PEM fuel cell environment using both ex-situ electrochemical techniques and in situ fuel cell testing. The kinetic ORR parameters for the FePc species each adsorbed on a pyrolytic graphite WE were evaluated at four temperatures (20, 40, 60, 80°C) in a novel half cell using cyclic voltammetry (CV) and rotating disk electrode (RDE) voltammetry. Kinetic ORR parameters included the overall ORR electron transfer number, reaction rate constants, cathodic Tafel slopes, electron transfer numbers in the rate determining step, and electron transfer co-efficients. An increase in temperature from 60°C to 80°C showed a decrease in the overall electron transfer number observed for all four substituted FePc species. A mechanism was also proposed based on the experimental results. The RDE results were confirmed using a rotating ring disk electrode (RRDE). From these RRDE results, the fraction of H₂0₂ produced (XH₂₀₂) at the disk during the ORR was calculated. These XH₂₀₂ values agreed with the overall ORR electron transfer numbers from the RDE results obtained under the same conditions. lron(Il) 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25 — hexadecachioro 29H,31H-phthalocyanine (FePcCI₁₆)was down selected for further investigation as the most stable and active substituted FePc species for the ORR. Both FePcCl₁₆ and the unsubstituted FePc, were supported on carbon and made into catalyst inks for carbon fibre paper (CFP) electrode testing, and then evaluated using CV in the N₂ purged, followed by the air saturated, electrolytes, respectively. Finally, MEA’s for fuel cell testing were made using FePc species catalyst ink cathodes, and commercial Pt/C anodes. The MEA’s were tested using custom designed and built fuel cell hardware. Open circuit voltages, polarization curves, and power curves were recorded. Initial results indicated the FePcCI₁₆ MEA’s showed superior stability, higher open circuit voltages, as well as better polarization and power curves when compared to the unsubstituted FePc species. It was found that FePc species with strongly electron withdrawing substituents, such as FePcCl₁₆ showed the highest stability and greatest ORR activity. FePc species, including pyrolized FeNx/C analogues, show much promise as alternatives to Pt in PEMFC’s, as well as dye sensitized solar cells (DSSC’s). / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

The value of the dipole moment ,μ, of NH in the A³π state was found to be 1.31 ± .03 Debye. This value was determined from data on the Stark effect measured from spectrograms of the A³π- X³Σ-, 3360 Å, band taken on a 3.4 meter grating spectrograph in third order giving a resolution of about 100,000. The theory of the Stark effect in molecules was taken from papers by W. G. Penny5 and Van Vleck and Hill9 . The magnitude of the electric field was determined from the Stark splitting of the hydrogen line Hβ according to the theory given in The Theory of Atomic Spectra6 . In the near future I should be able to complete work on the c’π→a’Δ, 3240 Å, band and give the values of the dipole moments for states c and a as well. Thus it will be possible to determine how the dipole moment changes with electronic configuration. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

This thesis is a report of a study on bone blood flow in adult dogs and rabbits. The effects of epinephrine and some other factors were investigated: (1) by direct observation of bone bleeding through drill holes and in the medullary cavity; (2) by measurement of changes in intramedullary pressure of long bones; and (3) by quantitative estimation of bone blood flow by the Fick principle. A technique was developed for measurement of the initial Sr⁸⁵ clearance by bone by dividing the bone uptake of Sr⁸⁵ by the integrated average concentration of Sr⁸⁵ in the systemic arterial blood. This clearance will represent at least a minimum bone blood flow. It should be equivalent to effective bone blood flow on the assumption that bone clears Sr⁸⁵ rapidly and almost completely from blood circulating through bone by exchange with calcium in bone, just as PAH clearance gives a measure of effective renal blood flow. The normal rate of bone blood flow in adult rabbits by the rate of initial Sr⁸⁵ clearance appeared to be at least 16 ml. per minute per 100 gm. of fresh bone which would represent about 5-10% of the resting cardiac output. The average intramedullary pressure of the femur in dogs was about 55 mm Hg, about 1/2 of the systolic systemic arterial blood pressure. Epinephrine caused a profound reduction in bone blood flow as indicated by reduced bone bleeding, a marked (65%) reduction in intramedullary pressure of bone marrow in the presence of persistently increased systemic blood pressure, and a significant (75%) reduction in Sr⁸⁵ clearance by bone. The changes in intramedullary pressure and in Sr⁸⁵ clearance by bone thus appear to correlate very well with changes in bone blood flow. / Medicine, Faculty of / Cellular and Physiological Sciences, Department of / Graduate