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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

"Working in the grave" the development of a health and safety system on the Witwatersrand gold mines, 1900-1939

Smith, Matthew John January 1993 (has links)
This thesis analyses the establishment of a health and safety system on the Witwatersrand gold mines in the period between the end of the South African War and the eve of World War Two. The period has been chosen, firstly, because the South African War had seriously disrupted production and the industry virtually had to start up again from scratch; secondly, because it was during this period that mine and state officials began to seriously investigate the reasons for the appalling mortality and morbidity rates on these mines; and, thirdly, because during this period some improvements did occur which were significant enough to enable the industry to warrant the lifting, in the latter part of the 1930s, of the ban on tropicals, enforced since 1913 as a result of their extremely high mortality rate. In the first thirty years of the twentieth century about 93 000 African miners died disease-related deaths and in the same period some 15000 African miners were killed in work-related deaths. In attempting to establish why so many African miners died, the thesis attempts to identify the diseases and accidents that caused these deaths and considers what attempts were made to bring mortality and morbidity rates down. Whilst the thesis is neither a history of gold mining in South Africa nor an economic history of South Africa in the period 1901 to 1939, it nevertheless, as detailed in the first chapter, places the health and safety system within the context of the wider political and economic forces that shaped the mining industry in this period. The need for a productive and efficient labour force, vital for the industry'S survival during a number of profitability crises in this period, forced the industry to reassess compound structures, nutrition and eventually the health of its work force. These issues of compounds, work and diet are discussed in chapters two, three and four. Appalling living and working conditions led to a high incidence of pulmonary diseases - TB, silicosis and pneumonia - which were the principal killers on the mines. Attempts to cure or prevent their occurrence are discussed in chapter five. Fear of disruptions to production ensured that the mining industry eventually also devoted considerable resources to accident prevention, a theme which is discussed in chapter six. The thesis concludes that the mining industry for much of this period was able to determine the pace of change; neither state officials nor African miners were able to significantly alter the tempo. In fact the industry was so successful that it was able to convince a number of government commissions in the 1940s that the migrant system had to stay, to ensure the wellbeing of the miner. This meant that despite considerable time, money and effort being spent on establishing a health and safety system on the gold mines, the mining industry was still of the opinion that the health of their workers was best served if they were sent home.
72

Die mondelinge taalgebruik van milieugestremde junior primêre leerlinge

Terblanche, Naomi Magdalena 11 March 2014 (has links)
M. Ed. (Educational Psychology) / The aim of this study was to determine whether any significant differences exist in the oral language usage of disadvantaged children and that of children from middle to upper socio-economic groups. The study was limited to Afrikaans-speaking children from the junior primary phase. The nature of these differences were also investigated...
73

The characterization of Pyrite from the Ventersdorp contact Reef of the Kloof Gold Mine in the Witwatersrand Basin in South Africa

Tibane, Lowanika Victor January 2013 (has links)
The approximately 2.9 Ga old Witwatersrand Basin of South Africa hosts different types of pyrite grains. The pyrite grains are hosted in different quartz pebble conglomerate reefs including the Ventersdorp Contact Reef (VCR). The various reefs are accessible from numerous goldfields. Regardless of years of studying the various types of pyrite grains from the VCR, there is still a disagreement as to their origins. Numerous pyrite grains of different types, shapes, and textures have been identified in the VCR of the Kloof Gold Mine. The origin of the different types of pyrite grains have been attributed to various mechanisms. Consequently, different depositional models were suggested for the mineralisation of the pyrite grains. Nevertheless, the style of mineralisation and origin of the different types of pyrite grains require further work especially for the VCR. This study determined whether a single or multiple processes were responsible for the formation of the different pyrite grains. The different types of pyrite grains including the rounded porous, rounded massive and angular massive grains were identified using a reflected light microscopy, scanning electron microscopy, and Röntec energy-dispersive x-ray spectroscopy. The above techniques were used to describe the shapes, sizes, and textures of the different types of pyrite grains in order to classify and group the pyrite grains for further investigation by chemical analysis. Identification and description of minerals associated with pyrite were conducted to determine the environment and conditions under which pyrite grains were formed. Genetic structures were identified in order to resolve whether the pyrite grains were transported or crystallised in situ. Different types of inclusions hosted in pyrite grains were identified and described to determine the nature of pyrite grains. Rounded zircon grains were identified in rounded massive pyrite grains, and the appearance the rounded zircon grains might suggest that the rounded massive pyrite grains formed later after the deposition of the Witwatersrand basin sediments. A particle induced x-ray emission, an electron microprobe, and a laser ablation inductively coupled plasma mass spectrometry were used to carry out chemical analysis of the major, minor and trace elements of the different pyrite grains. The chemical analyses were conducted to investigate and determine the chemical signatures and the composition of the different types of the pyrite grains to determine their processes of formation. Compositional zonation patterns and overgrowths of the pyrite grains were identified in order to determine whether the pyrite grains were formed through multiple mechanisms. The compositional zonation patterns were observed in the rounded porous pyrite grains. The zonations suggest multiple stages of growth processes resulting in most porous parts of the pyrite being enclosed by nearly pure pyrite. The rounded pyrite grains are generally containing high concentrations of Ni and Co as opposed to angular pyrite grains. The Ni/Co ration is low in the angular pyrite grains, but high in the rounded grains. The high Ni/Co ratio in rounded grains may be related to low-temperature sedimentary processes, whereas the low Ni/Co ratio in angular pyrite grains may indicate hydrothermal source. The differences between rounded and angular pyrite grains can be interpreted as a result of different genetic history, and origin from different sources. Thus the different pyrite grains formed under different chemical and atmospheric conditions, and by different depositional mechanisms. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Geology / unrestricted
74

Pyrite in the Mesoarchean Witwatersrand Supergroup, South Africa

Guy, Bradley Martin 20 August 2012 (has links)
Ph.D. / Petrographic, chemical and multiple sulfur isotope analyses were conducted on pyrite from argillaceous, arenaceous and rudaceous sedimentary rocks from the Mesoarchean Witwatersrand Supergroup. Following detailed petrographic analyses, four paragenetic associations of pyrite were identified. These include: 1) Detrital pyrite (derived from an existing rock via weathering and/or erosion). 2) Syngenetic pyrite (formed at the same time as the surrounding sediment). 3) Diagenetic pyrite (formed in the sediment before lithification and metamorphism). 4) Epigenetic pyrite (formed during metamorphism and hydrothermal alteration). It was found that the distribution of the pyrite varies with respect to the stratigraphic profile of the Witwatersrand Supergroup and depositional facies within the Witwatersrand depository. In this regard, the four paragenetic associations of pyrite are either scarce or absent in marine-dominated depositional environments, which occur in the lower parts of the succession and in geographically distal parts of the depository. Conversely, the four paragenetic associations are well represented in fluvial-dominated depositional environments, which occur in the middle and upper parts of the succession and in geographically proximal parts of the depository. However, it is worth noting that diagenetic pyrite in the West Rand Group occurs as in situ segregations in carbonaceous shale, whereas syngenetic and diagenetic pyrite in the Central Rand Group occurs as reworked and rounded fragments in fluvial quartz-pebble conglomerates. The strong association between fluvial depositional environments and sedimentary pyrite (syngenetic and diagenetic pyrite) infers a continental source of the sulfur (sulfide weathering or volcanic activity), whereas the lack of pyrite in marine depositional environments is consistent with the model of a sulfate-poor Archean ocean. The connection between epigenetic pyrite and the fluvial-dominated depofacies is probably related to the elevated concentrations of precursor sulfides (i.e., remobilization of syngenetic and early diagenetic pyrite) and the presence of organic carbon (conversion of metal-rich early diagenetic pyrite into pyrrhotite and base metal sulfides). In support of the petrographic observations above, it was found that the trace element chemistry of each paragenetic association of pyrite yields a distinctive set of chemical compositions and interelement variations (Co, Ni and As contents). Regarding detrital pyrite, two chemical populations can be distinguished according to grain size: 1) small grains (tens of μm’s) with high levels of metal substitution (up to wt. %) and interelement covariation and iv 2) large grains (>100 μm) with low levels of metal substitution (≤200 ppm). These two populations are thought to represent pyrite derived from sedimentary and metamorphosed source areas, respectively (see below). The trace element chemistry of diagenetic pyrite varies relative to the Fe-content of the host rock. Diagenetic pyrite from Fe-rich host rocks, such as magnetic mudstone and banded iron formation (BIF), generally contain low Ni contents (<500 ppm), moderate As contents (<1500 ppm) and relatively high Co contents (up to a few wt. %). Elevated concentrations of As probably reflect desorption of As from clays and Fe-oxyhydroxides during diagenetic phase transformations, whereas anomalous concentrations of Co are tentatively linked to the reductive dissolution of Mn-oxyhydroxides.
75

School climate as a cause of school dropout

Sinclair, Dorothea Wendy 11 February 2014 (has links)
M.Ed. / Research teams from the Department of Educational Sciences of the Rand Afrikaans University (RSA) and the Hubert H. Humphrey Institute of Social Ecology of the Ben Gurion University (Israel) have joined hands in a research project. Knowledge, experience and expertise were pooled in an endeavour to expose the causes leading to the dropout phenomenon amongst adolescents worldwide, and more specifically within their own countries. The development of prevention programmes to address the problem will be introduced in follow-up studies with a goal of reducing the number of school dropouts. The aim of this study is to compare disadvantaged standard seven at-risk and not at-risk pupils in order to determine whether or not school climate could be considered an influencing factor in early school leaving. The method of the research is twofold. A literature study constitutes the first part in which terminology, concepts, definitions, causes and consequences of dropout are discussed. The emphasis is placed on school climate in general and the relation between school climate and academic achievement in particular. This was followed by an empirical investigation to determine whether there are significant differences between at-risk and not at-risk standard seven pupils with regard to their perception of school climate. These pupils were identified by their teachers and their replies measured in a questionnaire. The empirical investigation involved standard seven pupils affiliated to five high schools in the Pretoria-Witwatersrand-Vereeniging area. In total, 734 pupils answered the questionnaire. The information was processed at the Statistical Consultation Service of the Rand Afrikaans University.
76

Heurostentics and subject didactic skills in the training of biology teachers

Rhodes, Basil Godfrey 31 July 2014 (has links)
D.Ed. (Didactics) / Please refer to full text to view abstract
77

Riglyne vir 'n wiskundeprogram vir junior sekondêre leergeremde leerlinge

Allers, Janet 08 September 2015 (has links)
M.Ed. / The object of this research project is to do an error analysis of standard five pupils' mathematics books and to to create guidelines for a mathematical programme, using direct instruction, learning strategies and problem solving skill ...
78

The petrogenesis of the volcanic rocks of the Witwatersrand triad in the Klerksdorp area, Transvaal

Bowen, Michael Peter January 1985 (has links)
Several hundred chemical analyses of early Proterozoic lavas of the Witwatersrand triad (incorporating the Dominion Group, Witwatersrand Supergroup and Ventersdorp Supergroup) in the Klerksdorp area, have revealed the presence of various distinct magma types. These essentially correspond to formally defined lithostratigraphic units, but several inconsistencies have necessitated the use of informal nomenclature. The lavas have been regionally metamorphosed to low-grade, greenschist facies assemblages. Original igneous textures are preserved, despite a metamorphic overprint. Metamorphism has resulted in a certain degree of random chemical remobilization. Ba, Sr, Rb, K₂0, Na₂0 and CaO have been highly mobile, and their usefulness in petrogenetic modelling is extremely limited. In contrast, Zr, Nb, Y, LREE's, Cr, Ni, Ti0₂ P₂0₅ and Al₂0₃ have remained immobile. Ti/Zr and Ti/P ratios together constitute efficient discriminating variables for characterizing the different magma types. Lava compositions range from primitive Mg-rich tholeiites to rhyolites, the bulk being tholeiitic andesites. Al₂0₃ contents do not exceed 15%, a feature which reflects the tholeiitic, as opposed to calcalkaline, character of these lavas. Two magma-types are present within the Dominion Group, which is a typical example of bimodal volcanism. The Dominion basic lavas are overlain by the Dominion acid porphyries, with a limited amount of interfingering. The basic lava suite is highly fractionated, with compositions ranging from Mg-, Cr- and Ni-rich tholeiites (close to primary mantle melts) to evolved tholeiitic andesites. The most primitive liquids evolved by 45% fractional crystallization of hornblende, followed by a further 70% crystallization of an orthopyroxene-plagioclase assemblage containing up to 3% sulphides. The Dominion porphyries are rhyolitic, display very limited compositional variation, and probably represent a crustal melt related to the same magmatic event which produced the basic lavas. The only lavas from the Witwatersrand Supergroup present in the Klerksdorp area are those of the Crown Formation (Jeppestown amygdaloid). These are tholeiitic dacites which display extremely limited compositional variation, and are unrelated to any of the other magmas of the Witwatersrand triad. The Ventersdorp Supergroup comprises 4 magma-types: The Kliprivierberg Group lavas at the base are subdivisible into 3 sub-types on the basis of Zr contents. (Zr>11Oppm) are the most evolved. They are tholeiitic andesites which display fairly limited compositional variation. It is likely that more evolved compositions are present in other areas where the porphyritic lavas which characterize this unit are better developed. The overlying Orkney lavas are characterized by 110ppm>Zr>90ppm. They are tholeiitic andesites of similar composition to the Alberton lavas, but have lower incompatible element levels, higher siderophile element levels, and are of extremely uniform composition. The uppermost Loraine/Edenville lavas range from magnesian tholeiites to tholeiitic andesites. They are distinguished by Zr< 90ppm, and contain the most primitive magmas af the Witwatersrand triad, with up to 17,5% MgO, 2600ppm Cr, 600ppm Ni and M-values up to 77. The most primitive liquids evolved by 38% fractional crystallization of orthopyroxene ∓ chromite, followed by 35% fractional crystallization of an extract containing clinopyroxene and plagioclase. The absence of olivine precipitation is a result of the inherently high Si0₂ content of the magma. The Loraine/Edenville, Orkney and Alberton lavas do not lie on a common liquid line of descent, but are probably consanguinous. The Platberg Group overlies the Kliprivierberg Group, and has a coarse-clastic sedimentary unit, the Kameeldoorns Formation, at the base. Three petrographically distinct porphyritic lava sequences overlie the Kameeldoorns Formation, namely the informal "Goedgenoeg formation", the Makwassie quartz-feldspar porphyries and the Rietgat Formation. Despite petrographic differences, the Goedgenoeg and Rietgat lavas are chemically indistinguishable and thus form a single magma-type. The Makwassie porphyries are dacitic in composition with a high proportion of feldspar and quartz phenocrysts. Rational variation trends are attributed to a nett loss of Si0₂ during secondary alteration. The porphyries are probably of crustal origin. The Goedgenoeg/Rietgat lavas display unusual chemistry and a broad, irrational compositional spectrum. They contain very high incompatible element levels, high nonnative quartz, as well as high MgO, M-values, Cr and Ni relative to the other tholeiitic andesites of the Witwatersrand triad. It is tentatively suggested that they are hybrid magmas containing both crust and mantle components, the former possibly represented by the Makwassie porphyries. Field evidence suggests that Platberg volcanism commenced directly after Klipriviersberg volcanism ceased, and was accompanied by a period of enhanced tectonic activity. The Platberg lavas thus probably reflect a crustal melting cycle associated with the Klipriviersberg magmatic event. The Allanridge lavas are the youngest rocks of the Witwatersrand triad. They are separated from the Platberg Group by a unit of flat-lying sediments, the Bothaville Formation, which was deposited after an extended period of peneplanation. The Allanridge lavas form a separate magma-type. They are tholeiitic andesites of similar composition to the Alberton lavas, but have higher incompatible element levels and are not consanguinous. The compositional similarities amongst the basic magma-types of the Witwatersrand triad suggests that all were generated in an hydrous mantle. Interelement ratio differences between the various magma-types nevertheless support the concept that the mantle was chemically heterogeneous during the early Proterozoic.
79

Assessment of the mineralogical variability of the A1, UE1A, and A5-reefs at Cooke Section, Rand Uranium, using MLA-based automated mineralogy

Mkhatshwa, Sindile Francisca 21 August 2012 (has links)
M.Sc. / This study focuses on the mineralogical variability of the A1, A5 and UE1A Elsburg reefs, obtained at Rand Uranium’s underground mining areas. A total of 133 reef samples, consisting of the Elsburg UE1A, A1 and A5-reefs have been obtained from Cooke 2 and 3 (two of the three Rand Uranium Mines) using the conventional chip sampling method. One of the challenges faced by Rand Uranium Gold Mines in the Cooke section area is the difficulty in differentiating between the various reef types by means of their macroscopic characteristics (colour, pebble types/sizes/shapes, sorting, matrix type, visible sulphide mineralization etc.). This difficulty led to this study which is aimed at utilizing mineral liberation analyzer (MLA)-based automated mineralogy to distinguish between the various reefs and to assess the mineralogical variation within the A1, A5 and UE1A-reefs. The mineralization in this area is hosted by the upper Central Rand Group of the Witwatersrand Supergroup. The main orebodies that are exploited at the mines occur within the Gemsbokfontein Member of the Elsburg Formation. These orebodies have been deformed into an east-west trending anticline at Cooke 3. The present study also attempts to prove or disprove the equivalence of the UE1A-reef on the western limb of the anticline to the A1 or A5-reefs on the eastern limb of the anticline on the basis of mineralogy. Representative splits of the samples were subjected to mineralogical abundance quantification as possible through quantitative MLA-based modal abundance protocols such as XMOD. A standard file on the various mineralogical phases encountered, was created on the 600F MLA and complemented by quantitative XRD (X-ray diffraction) data. Mineral abundances were quantified by MLA, based on integrated backscatter electron (BSE) images and energy dispersive spectrometry (EDS) analyses. Thirty one minerals have been detected using the MLA and they include phases such as quartz, pyrophyllite, chlorite, brannerite, gold, monazite and pyrite as well as minor unknown minerals. Only a few of the minerals are relatively more abundant within the reefs while the majority occurs in very low abundance. Albite, chlorite, muscovite, pyrite, pyrophyllite, quartz, uraninite and zircon are relatively more abundant than the rest of the minerals.
80

‘How open are our doors? A comparison of academic staff transformation at the University of Cape Town and the University of the Witwatersrand’.

Lewins, Kezia 28 February 2007 (has links)
Student Number : 0314897V - MA research report - School of Social Science - Faculty of Humanties / This research report asks ‘how effective has academic staff transformation been at the University of Cape Town (UCT) and the University of the Witwatersrand (Wits)?’ This question was examined from four angles: i) the historical engagement of UCT and Wits, as employers, with race, class and gender, ii) the impact of government directive and the legislative context on the transformation of higher education workplaces, iii) the institutional role and response of UCT and Wits to the race, class and gender of their academic staff and iv) academics’ experience of UCT and Wits as workplaces. The findings are based on in-depth interviews with 50 academic and senior executive staff at UCT and Wits. The results illustrate both continuity and change in the way in which academic staff experience institutions. Whilst there are progressive elements identified, there are also disconcerting expressions of prejudice, discrimination and harassment which undermine the transformation process.

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