3. Electronic Theses and Dissertations (ETDs) - All submissions

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Start date: 1950End date: 1979

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    The geology of the Otjosondu manganese area: south west Africa
    (1959) Roper, Harold
    Geological mapping and compilation of data from mining and prospecting operations in the Otjosondu area in South West Africa provided the information presented in this thesis. The geomorphology of the area is described and the general geology is discussed. Details of the complicated folding suffered by the Iamara rocks are presented. The petrology and petrography of' the outcropping representatives of the ancient sedimentary and intrusive rocks is described under the section on economic geology, interpretations of the complex structures of the ore bodies are presented. The mineralogy of the ores was studied by means of polished sections, X-ray diffraction and differential thermal analysis techniques. It is concluded from both field and laboratory evidence that these ores represent the metamorphosed equivalents of syngenetic manganese bearing sediments
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    The Morphology and Transport of Mucus in Mammalian Airways.
    (1975) Andre William Wessels van As
    The mucociliary clearance mechanisms in mammalian pulmonary airways have been re-examined. In this investigation Wistar rats, housed both under specific pathogen free (SPF) and normal animal house conditions, were examined. An intact airway . system from the trachea down to the level of the terminal bronchioles was used. The airway preparation was rapidly isolated and examined under carefully controlled in vitro conditions. Specimens remained viable for at least 10 h. Mucociliary activity was observed through the intact bronchial wall with the aid of incident light. This function could be examined at all levels of the pulmonary tree in the same specimen. In contrast to the previously described presence of a continuous mucous bl~ket, the morphology of mucus in the airways of the rat has been shown to be discontinuous. Mucus is present as discrete particles of varying size. Under the light microscope these particles appeared to fall into three categories: droplets less than 4 μm in diameter; flakes 10-70 μm in diameter; and plaques which are conglomerations of droplets and flakes. Scanning electron microscopy reveals that droplets (i.e. single particles) may be as small as 0,5 μm and that composite particles made up of numerous aggregated droplets may be as small as 5 μm in diameter. Plaques are conglomerations of these particles. In the normal intrapulmonary airways only smaller particles are seen and are transported over the individual metachronal fields. In the larger extralobar airways these particles move together to be transported in well defined streams which may be up to 500 μm wide. These streams may follow a winding course up the trachea and more than one may be in operation at a time. Under conditions of hypersecretion such as occurs with chronic respiratory disease in rats (CRD) the number of particles increase peripherally and plaques may be found in small airways. The transport of mucus is however still intermittent and it never becomes confluent. Acute bronchitis results in wide-spread abnormalities of ciliary activity and mucus transport, which leads to total disorganisation of pulmonary clearance. "Chronic bronchitis" associated with CRD results in more organised abnormalities of mucociliary activity. Cilia may become inactive, reverse the .direction of their effective stroke, beat retrogradely, and exhibit abnormal beat patterns which result in impaired mucus clearance. Squamous metaplastic areas further impede mucus transport. In general mucus transport rates were found to be faster in rats with "chronic bronchitis" than SPF rats, provided that the extent of the damage to the mucous membrane was ( not too great in the "bronchitic" animal. This finding was confirmed by the examination of airway preparations approximately 19 h after the exposure to a charcoal aerosol. While significant amounts of charcoal were retained at the bifurcations of bronchi in SPF rats, most of the charcoal was cleared in "bronchitic rats'.'. The only areas where particles were seen were on bronchitic patches or on whirlpools. The findings of this study indicated that mucus was present in a discontinuous form, and that in both SPF and non-SPF animals no evidence for a mucous blanket was found.
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    The Morphology and Transport of Mucus in Mammalian Airways.
    (1975) Andre William Wessels van As
    The mucociliary clearance mechanisms in mammalian pulmonary airways have been re-examined. In this investigation Wistar rats, housed both under specific pathogen system frfroeme (tShPeFt)raacnhdeanodrmowanl taonimthael lheovuelseofcotnhdeititoenrms, inwael rbe roexnacmhiionleeds . wAans uinsetadc. t airway The airway preparation was rapidly isolated and examined under carefully controlled in vitro conditions. Specimens remained viable for at least 10 h. Mucociliary activity was observed through the intact bronchial wall with the aid of incident light. This function could be examined at all levels of the pulmonary tree in the same specimen. In contrast to the previously described presence of a continuous mucous bl�ket, the morphology of mucus in the airways of the rat has been shown to be discontinuous. Mucus is present as discrete particles of varying size. Under the light microscope these particles appeared to fall into three categories: droplets less than 4 µm in diameter; flakes 10-70 µm in diameter; and plaques which are conglomerations of droplets and flakes. Scanning electron microscopy reveals that droplets (i.e. single particles) may be as small as 0,5 µm and that composite particles made up of numerous aggregated droplets may be as small as 5 µm in diameter. Plaques are conglomerations of these particles. In the normal intrapulmonary airways only smaller particles are seen and are transported over the individual metachronal fields. In the larger extralobar airways these particles move together to be transported in well defined streams which may be up to 500 µm wide. These streams may follow a winding course up the trachea and more than one may be in operation at a time. Under conditions of hypersecretion such as occurs with chronic respiratory disease in rats (CRD) the number of particles increase peripherally and plaques may be found in small airways. The transport of mucus is however still intermittent and it never be­ comes confluent. Acute bronchitis results in wide-spread abnormalities of ciliary activity and mucus transport, which leads to total disorganisation of pulmonary clearance. "Chronic bronchitis" associated with CRD results in more organised abnormalities of mucociliary activity. Cilia may become inactive, reverse the .direction of their effective stroke, beat retrogradely, and exhibit abnormal beat patterns which result in impaired mucus clearance. Squamous metaplastic areas further impede mucus transport. In general mucus transport rates were found to be faster in rats with "chronic bronchitis" than SPF rats, provided that the extent of the damage to the mucous membrane was not too great in the "bronchitic" animal. This finding was confirmed by the examination of airway preparations approximately 19 h after the exposure to a charcoal aerosol. While significant amounts of charcoal were retained at the bifurca­ tions of bronchi in SPF rats, most of the charcoal was cleared in "bronchitic rats .The only areas where particles were seen were on bronchitic patches or on whirlpools. The findings of this study indicated that mucus was present in a discontinuous form, and that in both SPF and non-SPF animals no evidence for a mucous blanket was found.
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    Abdominal decompression: a monograph
    (1963) Heyns, O. S.
    A short explanatory foreword to this monograph appears imperative. Abdominal decompression is the device offered for study and consideration to the reader of the following pages. If that reader accepts, for various cogent reasons, that abdominal decompression has certain effects upon the human organism— these being beneficial—and wishes to try its application, this is simple. Nothing is needed beyond the knowledge that the atmospheric pressure around the human trunk is to be reduced by one to three pounds a square inch of surface. The reader can then improvise some simple equipment and observe the effects of decompression upon him- or herself, upon another laboratory subject or on a patient who is pregnant, in labour, or suffering from menstrual pain or ordinary acute backache. The present work is but a record of the observable phenomena and their variations : matters which can be ascertained independently by the reader. As there is a wide range of application of the method and much time is needed to put possibilities to the test, an experimenter will be saved two years of work if he or she sets out equipped with the knowledge at present available.
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    Sedimentological control of gold and uraninite mineralisation in the White Reef of the West Rand
    (1975) Steyn, L S
    The primary objective of the study was to determine the controls of mineralization in the White Reef, which occurs at the base of the Bird Reef Stage of the Upper Witwatersrand System on the West Rand. It is a quartzite with scattered pebbles and occasional 'banket' conglomerates. The average gold content at 317 gm-cm per tonne is low, but uranium grade is amongst the highest on the Witwatersrand. In 1963 the author demonstrated some sedimentological properties of the Livingstone Reef are qualitatively related to gold content. More intensive studies have since confirmed the sedimentological control of gold mineralization. For instance, Pretorius (1974 a, 1975) recognizes a general fluvial fan geometry for the Witwatersrand reefs. However other factors, such as variations in environments, mechanisms of deposition, and behavior of the heavy minerals require further clarification; these form the main subject matter of this study. A pilot study established interrelationships between sedimentary features and ore grade. Follow-up work revealed systematic downslope changes. The reef was sampled on a systematic grid over the four West Rand mines. All pebbles were measured over complete reef sections. Measurements include 526 of reef thickness, 1 312 of crossbedding, 45 ripple marks, 2 of sand waves, 63 801 of pebble size and sorting, 63 761 for packing, 1 200 of fabric, 33 987 of composition, and 1 162 of shape and sphericity. Very large numbers of gold and uranium values, reef elevations, and thicknesses were compiled from records. The area investigated formed a subsiding part of a basin edge between granitic buttresses. Primary structures include the north-south Randfontein trough in the west, which controlled sedimentation from the Main Reef Stage onwards and the smaller north-east trending Witpoortjie trough. Additional control was exercised later by northeast and northwest-trending depressions. The major West Rand syncline running north-west, and the basin north of the Witpoortjie fault, are post-depositional features. The White Reef is comparable in geometry and sedimentological features to the Basal Reef (Sims, 1969) and generally conforms to the model of Pretorius (197 5). The subsiding Randfontein trough controlled the direction of major pay shoots, whilst smaller paystreaks formed along braided channels. The paleo-environment for the White Reef was that of a braided fluvial fan conforming to the model of Eynon and Walker (1974) for braided rivers. The distribution of depositional facies is related to fan geometry. (Abbreviations abstract)
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    The active failure of embankments of cohesionless materials
    (1965) Marais, G. v. R. (Gerrit van Rooyen)
    There are two methods available for the calculation of the disturbing forces in the active failure by sliding embankments of cohesionless material. The first is due to Hummel & Finnan (1921) and Trollope (1951) and the second is due to Rendulic (1938). Using these two methods in the stability analysis of a sliding failure of a 260 ft high earth dam at Cullinan, South Africa, showed that there was a significant difference in the horizontal thrusts as determined by the two methods. (Abbreviation abstract)
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    The Rebellion in South Africa 1914 - 1915
    (1962) Spies, S.B.
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    Comparison of activities, electrophoretic patterns and kinetic properties of some enzymes in normal and cancerous liver
    (1976-11) Hammond, Kathryn D.
    Glucose present in tissues is metabolised either by means of glycolysis, gluconeogenesis, glycogenesis or glycogenolysis, as shown in Figs. 1 and 2. Glycolysis occurs in almost all tissues, whereas gluconeogenesis is restricted mainly to liver and kidney cortex; the synthesis and degradation of glycogen takes place mainly in liver, skeletal muscle and heart. The patterns of carbohydrate metabolism characteristic of normal tissue are often altered in various diseased states; this is particularly evident in cancer. Tumour tissues, such as hepatoma, appear to lose the functional properties of adult differentiated tissue and their metabolism often seems to resemble that of rapidly-dividing, undifferentiated foetal tissue.
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    The missionaries on the eastern frontier of the Cape Colony, 1799-1853
    (1959) Williams, D
    This work attempts on the investigation into the activities of the missionaries of the Scottish (1), Wesleyan Methodist, and London Missionary Societies on the Eastern Frontier of the Cape Colony (2) during the years 1799-1853. The theme of the half-century is a triple failure: the failure to propagate Christianity among the amaXhosa, the failure to retain the goodwill of the colonists, and the failure to exercise significant political influence on the Cape administration. I have tried to explain why this occurred. There is a great need in South African historiography for detailed investigation into the contact between the missionaries and the Bantu. Missionary histories to date are of little value for an understanding of the problem of culture contact (J). With regard to the amaXhosa, there is no explanation, much less a frank admission, of the failure of the missionaries significantly to influence th4t race . Hitherto the tradition of missionary historiography has been to chronicle the increase of the number of mission institutions, and to accept this as evidence of the growth of Christianity as propagated by devoted and self-sacrificing missionaries. A re-assessment is long overdue. During and after the second half of the Nineteenth Century missionary circles were evaluating their achievements in Kaffirland, and were disappointed at the results. This missionary probe (4) has not been adequately reflected in contemporary South African missionary historiography. Of the missionary failure in Kaffirland, there is no doubt. Even today the amaXhosa is not a Christian nation. The publication of scurrilous attacks on missionaries in the form of pamphleteering literature (5) is symptomatic of the way in which such intellectual~ as are under the sway of Bantu Nationalism, is rejecting Christianity today (6). (Abbreviation abstract)
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