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The genesis and controls of gold mineralization south of Rehoboth, Namibia

  • Authors: Whitfield, Derek
  • Date: 1991
  • Subjects: Gold ores -- Geology -- Namibia , Gold ores -- Geology -- Africa, Southern
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4948 , http://hdl.handle.net/10962/d1005560 , Gold ores -- Geology -- Namibia , Gold ores -- Geology -- Africa, Southern
  • Description: Gold mineralization is hosted within gossanous quartz-haematite veins in volcano-sedimentary lithologies of the Klein Aub - Rehoboth basin of the Irumide Belt, Namibia. Mineralization and hydrothermal alteration are restricted to deformed lithologies particularly the metasediments. Lithological relationships, geochemistry and metallogenic characteristics of the Irumide Belt suggest an intra-continental rift setting. Copper mineralization is well known along the length of the belt, from Klein Aub in the southwest to Ghanzi in the northeast, whereas gold mineralization appears restricted to the Klein Aub Rehoboth basin. The gold is envisaged as having being leached initially from graben fill sequences during rift closure and basin dewatering. Location of the mineralization is strongly controlled by structure and lithological contact zones. Such zones are percieved as having acted as conduit zones for escaping mineralized fluids during basin closure and deformation. Apart from the lack of an effective mineralizing trap, all features consistent with the development of an ore deposit are present. The largest mineralization traps within the area studied are shear zones followed by lithological contact zones. The Mebi and Blanks gold mines are developed over large shear zones while the Swartmodder and Neuras gold mines are situated over mineralized lithological contacts. The Swartmodder copper mine yielded ore from a mineralized schist enclave within granite. Copper and gold occurrences are attributed to two contrasting styles of mineralization. Copper mineralization is suggested to have developed during initial rifting of the belt (ie. stratabound sedimentary exhalative type), while the gold and minor copper resulted from rift closure and basin dewatering. Although no economical orebody was realized during the course of this study a model is proposed for the development of mineralization within the Irumide basement lithologies as a working hypothesis for future exploration.
  • Full Text:
  • Date Issued: 1991

The genesis of ilmenite-rich heavy mineral deposits in the Bothaville/Delmas area, and an economic analysis of titanium, with particular reference to the Dwarsfontein deposit, Delmas district

  • Authors: Brennan, Michael Brendan
  • Date: 1991
  • Subjects: Heavy minerals -- South Africa -- Transvaal , Titanium , Geology -- South Africa -- Transvaal
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4949 , http://hdl.handle.net/10962/d1005561 , Heavy minerals -- South Africa -- Transvaal , Titanium , Geology -- South Africa -- Transvaal
  • Description: A number of ilmenite-rich heavy mineral deposits occur along the northern margin of the intracratonic Karoo basin, and are hosted by the fluvio-deltaic Middle Ecca Group. Coastal reworking of delta front sands within a regressive, microtidal shoreline may be considered as a depositional model for the development of the heavy mineral deposits. An economic analysis of titanium suggests long term positive demand, and sustained high prices for this commodity. An evaluation of the Dwarsfontein ilmenite-rich heavy mineral deposit, using available data, indicates how important it is for deposits of this type to be situated close to an upgrading plant or export harbour.
  • Full Text:
  • Date Issued: 1991

The geology, petrology and geochemistry of the mineralization and hydrothermal alteration at Ongeama, Ongombo and Matchless West Extension, Namibia

  • Authors: Moroni, Marilena
  • Date: 1991
  • Subjects: Geology -- Namibia , Petrology -- Namibia , Geochemistry -- Namibia
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5045 , http://hdl.handle.net/10962/d1007693 , Geology -- Namibia , Petrology -- Namibia , Geochemistry -- Namibia
  • Description: The Matchless Amphibolite Belt (Damara Orogen, Namibia) hosts several volcanogenic-exhalative, sediment-hosted stratiform cupriferous pyrite deposits. These are thought to be related to submarine volcanism during the early evolutionary stages of a narrow Damaran ocean, the Matchless Trough. The mineralized bodies examined (Ongeama, Ongombo and Matchless West Extension) are deformed and metamorphosed to low-medium grade (greenschist-amphibolite facies). They are associated with metapelite and amphibolite country rocks, and crop out as prominent limonite-rich gossans. The elongated shape of the sulphide bodies suggests a structural control. The mineralization normally consists of a variably developed massive sulphide portion, either quartz-, talc- or amphibole-bearing, and a stratigraphically overlying, extensive horizon of sulphide- and baryte-bearing exhalite (magnetite quartzite and less common talc- and actinolite-bearing schists). Lateral and vertical mineralogical changes within the mineralization match with significant variations in the element distribution. A metamorphosed and deformed alteration pipe, indicating the position of the fluid conduit, can be recognized in association with some ore bodies. The formation of quartz-muscovite and chlorite alteration envelopes (Ongeama, Matchless West Extension) and the presence of subtle mineralogical changes (Ongombo) in the immediate wallrocks, accompanied by extensive redistribution, leaching and introduction of elements from outside, suggest the hydrothermal metasomatic origin of the alteration zones. Element zoning within the mineralized bodies can be related to the original position of the vent, possibly coinciding with the intersection of the axis of the alteration pipe with the sulphide body. Cu, Zn, Au (pro parte) and Mo are enriched proximal to the vent, whereas Pb, Ba, Mn, Ag, Au, Sn, Bi and W enrichment characterizes the distal facies of the mineralization. In spite of the obliterating and disrupting effects of the regional dynamo-metamorphism, the element distribution within the mineralization and alteration zones examined is comparable with the geochemical trends observed in present-day mineralizing systems in early- stage oceanic environments (e.g. Guaymas Basin). During exploration for blind volcanogenic mineralization, the detection of hydrothermally altered rocks is fundamental in indicating the proximity to the mineralization. The localization of the alteration zone is also important in the interpretation of the regional geology of the explored area: in deformed terrains the assessment of the stratigraphic position of the alteration zone, relative to the mineralization, helps in establishing the polarity of the sequence.
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  • Date Issued: 1991

The healer's art : Cape Nguni diviners in the townships of Grahamstown

  • Authors: Hirst, Manton Myatt
  • Date: 1991
  • Subjects: Healers -- South Africa , Nguni (African people) -- Social life and customs , Divination -- South Africa , Medicine, Magic, mystic, and spagiric -- South Africa , Nguni (African people) -- Religion
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: vital:2084 , http://hdl.handle.net/10962/d1001601
  • Description: This is a study of Cape Nguni diviners practising in the townships of Grahamstown where, during the 1970s, there was a large and active concentration of diviners treating clients from the locality, the rural areas and even the large urban centres further afield. The study situates local diviners in the socio-economic, cultural and religious context of contemporary township Iife during the 1970s (see chapter 1 and section 2.1). The personalities and socio-economic circumstances of diviners (and herbalists) are described as well as their case-loads, the various problems they treat, the relations between them and their clients, the economics of healing and the ethics pertaining to the profession (see chapter 2) . Chapter three focuses on the various problems and afflictions - which are largely of an interpersonal nature - suffered by those who are eventually inducted as diviners and the ritual therapy this necessarily entails. Here we see how the diviner, what Lewis (1971) terms a 'wounded healer', becomes an expert in interpersonal and social relations as a result of suffering problems - largely connected to the family but not necessarily limited to it - in interpersonal relations and that require a ritual, and thus social, prophylaxis. The main theoretical argument is that the diviner, qua healer, functions as a hybrid of Levi-Strauss' s bricoleur and Castaneda's 'man of knowledge' artfully combining the ability of the former to invert, mirror or utilise analogies from linguistics to make everything meaningful and the ability of the latter to creatively bend reality . The diviner's cosmology is described in terms of a 'handy', limited but extensive cultural code/repertoire of signs, symbols and metaphors that is utilised in getting the message across to others and in which animals bear the main symbolic load (see chapter 4). This leads logically to a reappraisal of Hammond-Tooke's (1975b) well-known model of Cape Nguni symbolic structure particularly in so far as it pertains to the way in which diviners classify animals, both wild and domestic (see section 4.6). A striking evocation and confirmation of the view argued here, namely of the diviner as bricoleur/'man of knowledge', is contained in chapter five dealing with an analysis of the diviner's 'river' myth and the context, form and content of the divinatory consultation itself. Finally, the conclusions, arising out of this study of contemporary Cape Nguni diviners in town, are evaluated in the ligrht of Lewis's (1966, 1971, 1986) deprivation hypothesis of spirit possession (see chapter 6)
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  • Date Issued: 1991

The hermeneutic value of the Daseinsanalytic approach to dream interpretation in psychotherapy: a case study

  • Authors: Oberholzer, Sofia Adriana
  • Date: 1991
  • Subjects: Boss, Medard, 1903-1990 , Dreams -- Psychological aspects -- Case studies , Dream interpretation -- Case studies , Psychotherapy -- Case studies
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:3222 , http://hdl.handle.net/10962/d1012988
  • Description: The purpose of this study was to investigate the hermeneutic value of the Daseinsanalytic approach to dream interpretation in the process of psychotherapy. After delineating the Daseinsanalytic view on dream interpretation, with emphasis on the conceptualization of Medard Boss, the study explores the usefulness and validity of the case study as a method of investigating the content and process of psychotherapy. A psychodynamic formulation of the presenting problem is based on the conceptualization of the nature and etiology of neurosis as delineated by Andras Angyal, with particular reference to the pattern of noncommitment. The dreams included in the case material are then examined to determine to what degree they facilitated insight into the subjective experience and phenomenological existence of the dreamer, and what effect the dream interpretation based on the Daseinsanalytic approach had on the process of therapy. It is established that a phenomenological understanding of the client's dreams corresponds with his subjective experience of his emotional and existential condition, and that positive changes in the content of the dreams during the course of therapy correspond with overt, observable changes in his behaviour, ideation and mood. Based on these findings, the case study leads to the conclusion that the Daseinsanalytic approach to dream interpretation has hermeneutic value in the process of psychotherapy.
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  • Date Issued: 1991

The human skin-blanching assay for comparing topical corticosteroid availability

  • Authors: Smith, Eric W , Meyer, Eric , Haigh, John M , Maibach, Harold I
  • Date: 1991
  • Language: English
  • Type: Article
  • Identifier: vital:6433 , http://hdl.handle.net/10962/d1006604
  • Description: The human skin blanching assay remains in widespread use as a reliable, qualitative, comparative indicator of topical corticosteroid availability and potency. The experimental refinements promulgated by certain researchers in this field have yielded a versatile bioassay for the accurate assessment of new drugs or delivery vehicles. With the increasing appearance of generic topical corticosteroid formulations which compete with trade-name equivalents, the vital importance of this assay in regulatory affairs and assessing bioequivalence has been re-emphasized. It is stressed that if the blanching assay is to be used in this sphere, then multiple-reading trials must be conducted; important registration or clinical decisions cannot be made with any validity from short-term assessments.
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  • Date Issued: 1991

The informal sector in the Eastern Cape: a case study of New Brighton and Kwamagxaki, Port Elizabeth

  • Authors: Sofisa, Thembela Nicholas
  • Date: 1991
  • Subjects: Informal sector (Economics) -- South Africa -- Port Elizabeth , Self-employed -- South Africa , New Brighton (Port Elizabeth, South Africa) , Port Elizabeth (South Africa) -- Economic conditions , KwaMagxaki (Port Elizabeth, South Africa)
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:934 , http://hdl.handle.net/10962/d1002667 , Informal sector (Economics) -- South Africa -- Port Elizabeth , Self-employed -- South Africa , New Brighton (Port Elizabeth, South Africa) , Port Elizabeth (South Africa) -- Economic conditions
  • Description: Recently, researchers have shown enormous interest in the informal sector due to extensive poverty and rising unemployment trend in the South African economy. These problems have worsened in the Port Elizabeth economy, as most entrepreneurs have scaled down their operations or liquidated their businesses due to a structural decline in the manufacturing sector and periodic recessions in the national economy. Undoubtedly, the informal sector has become a reasonable economic alternative as far as income accumulation and employment generation. The present study shows that the informal sector is characterised mainly by self-employment and also the income from this sector has also improved the standard of living of most sampled households in New Brighton and KwaMagxaki. The aim of this thesis, then, is to evaluate the nature, extent, meaning and influence of the informal sector in the Port Elizabeth Black economy. However, this can only be achieved once the informal sector is placed within the appropriate theoretical framework. This is done by comparing and contrasting the different conceptualisations of the informal sector in the literature. In conclusion, the thesis combines the different conceptualisations of the informal sector in the literature with the empirical evidence from the Port Elizabeth townships' informal sector. The important findings of the study are: The informal sector is mainly characterised by distributive activities than productive activities. Women comprised 62% of the informal sector. Economically-active members of the economy are in the informal sector. Education levels in this sector are relatively low. The informal sector is characterised by one-man businesses with few employees who are also family members. There was no trace of migrants in the informal sector. The informal sector is characterised by linkages. Informal income alleviates conditions of poverty. Policies have to implemented for the development of the informal sector. Twenty-three percent of the households in New Brighton were in the informal sector and only 6% in KwaMagxaki. Although, this study focuses in Port Elizabeth, it is the intention that the results presented will provide a broad overview of what the informal sector is.
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  • Date Issued: 1991

The nature and origin of gold mineralization in the Tugela valley, Natal Structural and Metamorphic Province

  • Authors: De Klerk, Ian Duncan
  • Date: 1991
  • Subjects: Gold ores -- Geology -- South Africa , Gold mines and mining -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4979 , http://hdl.handle.net/10962/d1005591 , Gold ores -- Geology -- South Africa , Gold mines and mining -- South Africa
  • Description: The project area is situated within the Tugela Valley, located in the Northern Marginal Zone of the Natal Structural and Metamorphic Province, and this work outlines the different styles of gold mineralization found in the Tugela Valley. Two different styles have been recognized and both have economic significance:- 1) Epigenetic shear zone-hosted gold occurs in late-stage relatively undeformed thin quartz veins confined to shear zones, and is present in both the greenschist facies Natal Thrust Belt and the amphibolite facies Natal Nappe Complex. However the vast majority of these occurrences are concentrated within the thrust front (i.e. the Natal Thrust Belt). The gold grades (up to 7 g/t) and the hydrothermal alteration assemblages associated with the epigenetic deposits have been documented. 2) An as yet unrecognized occurrence of syngenetic gold mineralization is found associated with the sediment-hosted exhalative massive, to semi-massive, sulphides of the iThuma prospect, located within the amphibolite facies Natal Nappe Complex. Here gold (up to 3 g/t) is concentrated together with the main sulphide are, as well as some gold enrichment (230ppb) in the hydrothermally altered footwall feeder pipe. It is proposed that the epigenetic mineralization was formed as a consequence of the northward directed abduction of the major thrust slices of the Natal Nappe Complex. This increased the permeability of the rocks and provided channelways for the focussing of fluids. Deposition took place at the thrust front where metamorphic hydrothermal fluids interacted with meteoric water.
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  • Date Issued: 1991

The notion of physicality in vocal training for the performer in South African theatre, with particular reference to the Alexander technique

  • Authors: Cox, Frances Jayne
  • Date: 1991
  • Subjects: Voice culture , Alexander technique , Drama -- Study and teaching
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2134 , http://hdl.handle.net/10962/d1002366 , Voice culture , Alexander technique , Drama -- Study and teaching
  • Description: Voice training has been influenced by separatist attitudes which have allowed for classes which train the body to be separate from those which train the voice. This study acknowledges that to train an actor in separate compartments and then expect the completeness of human expression in performance, is to train under false pretences. There is a need to address the imbalance of separatism and this is examined within the context of voice training. An holistic approach to voice training forms the basis of the argument, which focuses on the need to re-educate the notion of physicality in voice training. Chapter one proposes an understanding of the notion of physicality by drawing on the attitudes of selected theatre practitioners towards the physical nature of the theatre encounter. The expressive energies of the actor's body are responsible for the physicalisation of a play; for this reason the movement of voice and speech is not only examined as source movement, but also as the movement of an actor's response and communication. Chapter two examines some practices which led to attitudes of separatism in voice training, and introduces prevalent practices which are attempting to involve the energy of the physical experience. Chapter three proposes that the Alexander technique be used as the foundation for an awareness of individual physicality. Where chapter one examines the theory of this notion, chapter three proposes an experiential understanding of the same. The Alexander technique is a training in effective body use and it's principles are fundamental to an awareness of body use and functioning. It is argued that these principles should underlie a re-education of physicality. The final chapter of the thesis argues for physicality in South African voice training programmes which would complement the physicality of contemporary theatre forms. It is hoped that this study will provide further incentive for the continued review and adjustment of drama training in South Africa.
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  • Date Issued: 1991

The pineal gland as a model to elucidate the primary mode of action of sympathoactive agents

  • Authors: Welman, Alan David
  • Date: 1991
  • Subjects: Pineal gland , Cythochemistry
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:3876 , http://hdl.handle.net/10962/d1001610
  • Description: An attempt was made to use the pineal gland as a model for the study of the primary mode of action of sympathoactive agents. Two drugs were investigated, viz. alpha-methyldopa and ephedrine whose mode of action is not entirely clear. Organ cultures of pineal glands from rats treated chronically with alpha-methyldopa showed enhanced conversion of radioactive serotonin to melatonin (aMT) , as well as its precursor Nacetylserotonin (aHT). This treatment was also found to raise Nacetyltransferase (NAT) activity. These increases associated with alpha-methyldopa treatment were further enhanced by the beta-adrenergic agonist, isoproterenol, suggesting a supersensitivity-type effect occurring at the level of the beta-receptor. A subsequent binding study, however, showed a decrease in beta-receptor binding with exposure to alpha-methyldopa, providing mitigating evidence against the occurrence of a supersensitivity phenomenon. It is possible that a metabolite of alpha-methyldopa acts as an alpha 1 and beta-adrenergic agonist, resulting in greater melatonin (aMT) and N-acetylserotonin (aHT) synthesis than by a beta-adrenergic agonist, isoproterenol. Combined treatment of pineals with alpha-methyldopa and an alphareceptor blocker, phentolamine, resulted in melatonin (aMT) , Nacetylserotonin (aHT) , and N-acetyltransferase (NAT) activity levels which were lower than those obtained with alpha-methyldopa treatment alone, thus confirming the alpha-adrenergic activity of the metabolite of alpha-methyldopa. Additional pineal metabolites were isolated and measured simultaneously in the organ culture experiments. Organ cultures of rat pineal glands treated with ephedrine showed raised levels of melatonin (aMT) and N-acetylserotonin (aHT). Treatment with ephedrine also produced raised N-acetyltransferase activity. A further enhancement of these parameters was induced by norepinephrine, suggesting a supersensitivity-type effect occurring at the level of the beta-adrenergic receptor. Rats were treated with reserpine (a norepinephrine depleter) and the pineals exposed to ephedrine. Endogenous norepinephrine normally released by the action of ephedrine was thus absent, and under these conditions, levels of melatonin (aMT) and N-acetylserotonin (aHT) were reduced. N-acetyltransferase (NAT) activity was also reduced, but maintained levels pointing to substantial adrenergic activity of ephedrine as well as norepinephrine released by virtue of the drug's action. A subsequent binding study showed a decrease in beta-adrenergic receptor binding with exposure to ephedrine and a further decrease in ephedrine treated pineals from reserpine treated rats, thus ruling out the occurrence of a supersensitivity phenomenon. It is possible that both ephedrine and released norepinephrine have alpha- and beta-receptor activity. Additional pineal metabolites were isolated and measured in the organ culture experiments. A 16-hour time profile of the production of melatonin (aMT) and N-acetylserotonin (aHT) with norepinephrine and ephedrine treatment provided useful information regarding the course of action of the two agents. A pineal cell-culture system was developed and exposed to ephedrine and norepinephrine. N-acetyltransferase (NAT) activity levels measured after exposure to these agents were raised, confirming the adrenergic activity of both in the model. Finally, an HPLC system coupled to a UV detector was used in an attempt to measure melatonin (aMT) extracted from pineal organ culture media. The results showed that melatonin could be measured by this method, however, a more sensitive detection system was recommended for future work.
  • Full Text:
  • Date Issued: 1991

The pineal gland as a model to elucidate the primary mode of action of sympathoactive agents

  • Authors: Welman, Alan David
  • Date: 1991
  • Subjects: Pineal gland , Cythochemistry
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4279 , http://hdl.handle.net/10962/d1002005 , Pineal gland
  • Description: An attempt was made to use the pineal gland as a model for the study of the primary mode of action of sympathoactive agents. Two drugs were investigated, viz. alpha-methyldopa and ephedrine whose mode of action is not entirely clear. Organ cultures of pineal glands from rats treated chronically with alpha-methyldopa showed enhanced conversion of radioactive serotonin to melatonin (aMT) , as well as its precursor Nacetylserotonin (aHT). This treatment was also found to raise Nacetyltransferase (NAT) activity. These increases associated with alpha-methyldopa treatment were further enhanced by the beta-adrenergic agonist, isoproterenol, suggesting a supersensitivity-type effect occurring at the level of the beta-receptor. A subsequent binding study, however, showed a decrease in beta-receptor binding with exposure to alpha-methyldopa, providing mitigating evidence against the occurrence of a supersensitivity phenomenon. It is possible that a metabolite of alpha-methyldopa acts as an alpha 1 and beta-adrenergic agonist, resulting in greater melatonin (aMT) and N-acetylserotonin (aHT) synthesis than by a beta-adrenergic agonist, isoproterenol. Combined treatment of pineals with alpha-methyldopa and an alphareceptor blocker, phentolamine, resulted in melatonin (aMT) , Nacetylserotonin (aHT) , and N-acetyltransferase (NAT) activity levels which were lower than those obtained with alpha-methyldopa treatment alone, thus confirming the alpha-adrenergic activity of the metabolite of alpha-methyldopa. Additional pineal metabolites were isolated and measured simultaneously in the organ culture experiments. Organ cultures of rat pineal glands treated with ephedrine showed raised levels of melatonin (aMT) and N-acetylserotonin (aHT). Treatment with ephedrine also produced raised N-acetyltransferase activity. A further enhancement of these parameters was induced by norepinephrine, suggesting a supersensitivity-type effect occurring at the level of the beta-adrenergic receptor. Rats were treated with reserpine (a norepinephrine depleter) and the pineals exposed to ephedrine. Endogenous norepinephrine normally released by the action of ephedrine was thus absent, and under these conditions, levels of melatonin (aMT) and N-acetylserotonin (aHT) were reduced. N-acetyltransferase (NAT) activity was also reduced, but maintained levels pointing to substantial adrenergic activity of ephedrine as well as norepinephrine released by virtue of the drug's action. A subsequent binding study showed a decrease in beta-adrenergic receptor binding with exposure to ephedrine and a further decrease in ephedrine treated pineals from reserpine treated rats, thus ruling out the occurrence of a supersensitivity phenomenon. It is possible that both ephedrine and released norepinephrine have alpha- and beta-receptor activity. Additional pineal metabolites were isolated and measured in the organ culture experiments. A 16-hour time profile of the production of melatonin (aMT) and N-acetylserotonin (aHT) with norepinephrine and ephedrine treatment provided useful information regarding the course of action of the two agents. A pineal cell-culture system was developed and exposed to ephedrine and norepinephrine. N-acetyltransferase (NAT) activity levels measured after exposure to these agents were raised, confirming the adrenergic activity of both in the model. Finally, an HPLC system coupled to a UV detector was used in an attempt to measure melatonin (aMT) extracted from pineal organ culture media. The results showed that melatonin could be measured by this method, however, a more sensitive detection system was recommended for future work
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  • Date Issued: 1991

The precambrian iron-formations in the Limpopo belt as represented by the magnetite quartzite deposits at Moonlight, Koedoesrand area, Northern Transvaal

  • Authors: Badenhorst, Jaco Cornelis
  • Date: 1991 , 2013-02-20
  • Subjects: Iron ores -- Geology -- South Africa , Quartzite -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5064 , http://hdl.handle.net/10962/d1013309
  • Description: This dissertation is based largely on data that was accumulated during the execution of an exploration program by Iscor Ltd in the Northern Transvaal. The program included geological mapping, geophysical surveys and drilling, on Precambrian iron-formations in the Central Zone of the Limpopo Belt. The structure, stratigraphy, metamorphism, and economic importance of the magnetite quartzites and associated lithologies of the Moonlight prospect are discussed. The lithologies underlying the Moonlight prospect area consist of various pink- and grey-banded gneisses and pink granulite, together with a variety of metasedimentary supracrustal rock-types and concordant serpentinite bodies. The gneissic rock-types consist of chlorite-quartz-feldspar gneiss, chlorite-quartz-feldspar augen gneiss, hornblende-quartz-feldspar gneiss, biotite-quartz-feldspar gneiss, felsic and mafic granulite, and foliated amphibolite. The metasedimentary lithologies are represented by calc-silicates and marble, white quartz-feldspar granulite, magnetite quartzite, metaquartzite and garnet-bearing granulite and gneiss (metapelites). The concordant ultramafic bodies consist of serpentinite with lesser amphibolite, dunite, and chromitite. Intrusive pegmatites and diabase dykes are also present in the prospect area. Metamorphism reached granulite-facies, and more than one retrqgrade metamorphic event is recognized . Amphibolite-facies assemblages are present, but it is uncertain whether they represent another retrograde event . Polyphase deformation has produced intense and complex folding , resulting in irregular magnetite quartzite orebodies. The high metamorphic grades have resulted in medium- grained recrystallization of the magnetite-quartzites with a loss of prominent banding often associated with these rock-types . The magnetite quartzite occurs as three seperate but related ore zones, consisting of one or more ore-bands seperated by other lithologies. All three zones form poor outcrops and suboutcrops in a generally flat lying and sand covered area. · Although representing a low-grade iron ore (32% total Fe), the magnetite quartzite deposits at Moonlight are regarded as potentially viable due to the large opencast tonnages available at low stripping ratios, and the relatively cheap and easy beneficiation process needed to produce a magnetite concentrate with 69-70% total Fe.
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  • Date Issued: 1991

The sedimentology of the Zerrissene turbidite system, Damara Orogen, Namibia

  • Authors: Swart, Roger
  • Date: 1991
  • Subjects: Sedimentology Sediments (Geology) -- Namibia Sedimentation and deposition Turbidites
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5000 , http://hdl.handle.net/10962/d1005613
  • Description: The Zerrissene turbidite system of central-western Namibia is a late Proterozoic sequence which consists of dominantly siliciclastic turbidites interbedded with minor turbiditic and hemipelagic marbles. The basin in which these sediments were deposited is located at the junction of the coastal and intra-cratonic arms of the Pan-African Damara Orogen, and an understanding of the sedimentary evolution of this basin is therefore important to the understanding of the development of the orogen as a whole. One major and two minor phases of folding have deformed the sediments, but the grade of metamorphism is low and sedimentary structures are often well preserved. Further, the area lies entirely within the Namib Desert and the lack of vegetation cover results in good outcrops providing an unusual opportunity for examining a large Precambrian turbidite system. The system consists of five formations: three siliciclastic and two mixed carbonatesiliciclastic units. The floor of the system is not exposed, and the oldest sedimentary rocks which outcrop are siliciclastics of the Zebrapiits Formation. This is overlain successively by the Brandberg West Formation (dominantly calcareous), the Brak River Formation (siliciclastic), the Gemsbok River Formation (calcareous) and the Amis River Formation (siliciclastic). Nine silicilastic turbidite facies have been recognised in the basin. These are facies A₂ (disorganised onglomerates), B₁ (horizontally laminated to massive greyackes), C₂ ("classical" turbidites), Dl (sandstone-shale couplets with base cut-out Bouma sequences), D₂ (sandstone-shale couplets with less sand than shale and base cut-out Bouma sequences), E (coarse, discontinuous sandstone-shale couplets), F (slumped units), G (shale) and H (glacial dropstones). Four facies are associated with the carbonate horizons, and these carbonate facies are given the suffix c to distinguish them from similar siliciclastic facies. These are facies Ac (disorganised and graded marble breccias), facies Cc (graded carbonates), facies Gc (hemi-pelagic marbles) and facies G (pelagic shales). The basal Zebrapiits Formation is made up of relatively thin packages of thin- to thickbedded, laterally continuous facies D₁, D₂ and B₁ beds encased in thick envelopes of shale. This type of sequence is typical of a distal lobe-fringe, and requires an unconfined basin-floor on which it can develop. The overlying Brandberg West Formation consists of a basal portion of interbedded facies Cc and G, followed by a sequence dominanted by facies Gc. This sequence is interpreted as representing outer-apron carbonate turbidites, derived from multiple point sources (facies Cc), with background pelagic settling (facies G) overlain by hemi-pelagic deposits (facies Gc). A reversal back to siliciclastic turbidites followed with deposition of the Brak River Formation. This sequence comprises relatively thick packages of laterally continuous facies B₁, D₁, and D₂ beds sandwiched between facies G shales, a succession characteristic of a lobe to lobe-fringe environment with intermittent abandonment of lobes. An unconfined basin floor adjacent to a passive margin is required for the development of this type of sequence. Glacial dropstones (facies H) are found in the upper portions of this formation, and slumped beds are also present (facies F), but are uncommon. The facies F beds are only found in association with facies H and are therefore considered to be genetically related. Slumping of beds was possibly caused by an oversupply of sediment from ice-rafting which caused instability. The overlying Gemsbok River Formation has a sequence similar to the Brandberg West Formation in that the basal portion consists of interbedded facies Cc and G, which is overlain by a thick sequence of largely facies Gc beds. Minor facies Ac beds occur near the top of the overall sequence. This formation is interpreted as an outer-apron succession with the facies Ac beds representing distal inner-apron deposits, indicating progradation of the system. The youngest unit in the basin, the Amis River Formation, shows strong lateral variation from west to east. In the west the sequence comprises laterally continuous facies B₁, C₂, D₁ and D₂ with rare, discontinuous facies E beds. Facies G is relatively minor in the sequence. In the east the succession is dominated by facies D₁, D₂ and G, and this succession is interpreted as a sequence of distal turbidites which were deposited on a basin-plain. The system developed by aggradation rather than progradation as only minor cycles are developed. Geochemical and petrological features indicate that the entire siliciclastic system was derived from a granite-recycled orogen terrane. Palaeocurrent data are unreliable because of the deformation, but transport was initially from the south-west, moving later to the west and north-west. The provenance of the carbonates is uncertain as reliable palaeocurrent indicators are rare, but they could have been derived either from South America or from the extensive carbonate deposits developed on the north-western margins of the basin. The Zenissene siliciclastic turbidite system represents the distal portion of a major submarine turbidite system, the more proximal parts of which now lie west of the exposed basin, either under the Atlantic Ocean or in eastern South America. The calcareous deposits developed as an apron adjacent to a multiple point source, the position of which is at present unknown.
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  • Date Issued: 1991

The shadowed corners of sunlit ruins: Gothic elements in twentieth century children's adventure fiction

  • Authors: Wagenaar, Peter Simon
  • Date: 1991
  • Subjects: Children's literature -- 20th century -- History and criticism , Gothic literature
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2250 , http://hdl.handle.net/10962/d1002293 , Children's literature -- 20th century -- History and criticism , Gothic literature
  • Description: This thesis examines the way in which children's adventure fiction makes use of Gothic features, how these features have been modified for a younger audience and how these modifications have been influenced by other developments in children's and popular fiction: Chapter One sets out to define the nature of Gothic and isolate those aspects of it relevant to the proposed study. It puts forward a theory to account for the movement of Gothic trends into later children's fiction. Chapter Two examines the use of landscape, setting and atmospheric effects in Gothic and the way in which children's fiction has used similar trappings to create similar effects. Children's fiction, emphasising pleasurable excitement rather than fear has, however, muted these effects somewhat and played down the role of the supernatural, so intrinsic to Gothic. Chapter Three emphasises the Gothic's use of stereotypes, focusing on the portrayal of heroes and heroines. Those of children's fiction are portrayed very similarly to those of Gothic and the chapter compares and, on occasion, contrasts them noting, inter alia, their adherence to rigid moral codes and narrowly defined norms of masculine and feminine behaviour. Chapter Four looks at the portrayal of villains and the way in which their appearance defines them as such (as, indeed, does that of heroes and heroines). It examines in some detail their relationship to and interaction with the heroes and heroines, noting, for example, the 'pseudo-parental' role of villains who are characteristically older and in socially approved positions to exert power over heroes and heroines. The Conclusion addresses the fantasy aspect of these novels,referred to several times in passing in the course of earlier chapters, and comments on how the features detailed in Chapters Two, Three and Four all operate within the conventions of a fantasy.
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  • Date Issued: 1991

The shifting focus of theology : from texts to questions to praxis : inaugural lecture delivered at Rhodes University

  • Authors: Gaybba, Brian P
  • Date: 1991
  • Subjects: Theology , Theology -- Methodology
  • Language: English
  • Type: Text
  • Identifier: vital:628 , http://hdl.handle.net/10962/d1020697 , ISBN 0868102199
  • Description: Inaugural lecture delivered at Rhodes University , Rhodes University Libraries (Digitisation)
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  • Date Issued: 1991

The Springfontein prospect : a case study of a tertiary age epithermal hot spring deposit in the Eastern Cape

  • Authors: Nichols, Richard Lionel
  • Date: 1991
  • Subjects: Hot springs -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5058 , http://hdl.handle.net/10962/d1012963
  • Description: The Springfontein Prospect is a Tertiary aged epithermal Hot Spring deposit that was investigated for precious metal mineralisation. It is located some 14 kilometres due west of East London (Cape Province), within Beaufort Group sediments and Karoo dolerite. Prior to the work described in this case study, the location was known for it's abundant plant fossils and barite mineralisation. A gossan sample collected near the main barite vein returned 1,07 g/t Au and 26,6 g/t Ag. Remote sensing studies of the site revealed a set of north-south lineaments paralleling the barite vein system. Geophysical surveys confirmed this orientation and revealed an extensive alteration system underlying the prominent sinter terrace. A detailed soil geochemical survey returned elevated values in the classical epithermal gold mineralisation element suite (Rg, Tl, As, Bi, Sb, Te, Mo, Ba and Pb - Bonham, 1986). Trenching of geochemical anomalies revealed zones of intense argillic alteration and vein stockworks). Four percussion and three diamond drill holes intersected a 'feeder-fissure' system of veins, alteration and brecciation, but failed to repeat gold levels seen at surface. Mineralogical and petrographic studies of the cores determined temperatures of formation of important indicator minerals (e.g. adularia and zeolites). Litho-geochemical work revealed mercury (and thallium) to be most elevated in the feeder systems. Stratigraphic and paleontological observations determined that the Springfontein Tertiary deposit was clearly different to the other siliceous (silcrete) units that crop out in the Eastern Cape region. A number of distinguished visitors to the prospect, with epithermal deposit experience, confirmed that the characteristics and dimensions of the system is within those of mineralised deposits elsewhere. A brief review of current epithermal models are presented. The conceptual geological model for the Springfontein prospect evolved through the exploration programme. The final consensus is that it best fits Bonham's (1986) alkalic model and the Tertiary epithermal event was sustained by rifting associated with the break-up of Gondwanaland.
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  • Date Issued: 1991

The synthesis of sound with application in a MIDI environment

  • Authors: Kesterton, Anthony James
  • Date: 1991
  • Subjects: Computer sound processing -- Research , Music -- Data processing -- Research , MIDI (Standard)
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4678 , http://hdl.handle.net/10962/d1006701 , Computer sound processing -- Research , Music -- Data processing -- Research , MIDI (Standard)
  • Description: The wide range of options for experimentation with the synthesis of sound are usually expensive, difficult to obtain, or limit the experimenter. The work described in this thesis shows how the IBM PC and software can be combined to provide a suitable platform for experimentation with different synthesis techniques. This platform is based on the PC, the Musical Instrument Digital Interface (MIDI) and a musical instrument called a digital sampler. The fundamental concepts of sound are described, with reference to digital sound reproduction. A number of synthesis techniques are described. These are evaluated according to the criteria of generality, efficiency and control. The techniques discussed are additive synthesis, frequency modulation synthesis, subtractive synthesis, granular synthesis, resynthesis, wavetable synthesis, and sampling. Spiral synthesis, physical modelling, waveshaping and spectral interpolation are discussed briefly. The Musical Instrument Digital Interface is a standard method of connecting digital musical instruments together. It is the MIDI standard and equipment conforming to that standard that makes this implementation of synthesis techniques possible. As a demonstration of the PC platform, additive synthesis, frequency modulation synthesis, granular synthesis and spiral synthesis have been implemented in software. A PC equipped with a MIDI interface card is used to perform the synthesis. The MIDI protocol is used to transmit the resultant sound to a digital sampler. The INMOS transputer is used as an accelerator, as the calculation of a waveform using software is a computational intensive process. It is concluded that sound synthesis can be performed successfully using a PC and the appropriate software, and utilizing the facilities provided by a MIDI environment including a digital sampler.
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  • Date Issued: 1991

The textbook as a major source of difficulty in the teaching and learning of geography through the medium of English in Standard 3 in black primary schools

  • Authors: Langhan, David Patrick
  • Date: 1991
  • Subjects: Children, Black -- Education -- South Africa , Geography -- Textbooks , Geography -- Study and teaching (Primary) -- South Africa , Language and education -- South Africa
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2335 , http://hdl.handle.net/10962/d1002017 , Children, Black -- Education -- South Africa , Geography -- Textbooks , Geography -- Study and teaching (Primary) -- South Africa , Language and education -- South Africa
  • Description: This dissertation provides evidence to suggest that teaching/learning difficulties with geography in Std 3 are largely attributable to textbooks which fail as well constructed discourse and include uninterpretable illustrations. The discourse properties most likely to affect the readability of textbooks intended for ESL/EFL pupils are identified. Selected passages from two widely used Std 3 geography textbooks are analysed in terms of these properties, and are shown to fail extensively as well constructed discourse. Following classroom observation and informal interviews which confirmed the inappropriacy of the texts for Std 3 pupils, the passages were re-written, following the necessary properties of well constructed expository discourse. The readability of these two sets of texts was then tested on a group of nine Std 3 teachers in two structured interviews. The findings reveal that the re-written passages are significantly more readable than the textbook passages. Recommendations that affect education authorities, curriculum designers, syllabus makers, textbook authors, publishers and teacher training colleges are provided
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  • Date Issued: 1991

The transitional role of the Xhosa oral poet in contemporary South African society

  • Authors: Kaschula, Russell H
  • Date: 1991
  • Subjects: Folk poetry, Xhosa Xhosa (African people) -- Religion Xhosa (African people) -- Social life and customs Xhosa poetry Laudatory poetry
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:3563 , http://hdl.handle.net/10962/d1002085 , https://orcid.org/0000-0002-5481-6748
  • Description: This thesis outlines the changing role of the Xhosa imbongi in contemporary South African society. The changing socio-economic and political scenario in South Africa, and the way in which the imbongi is adapting in order to accommodate new pressures created by these changes, form an integral part of this thesis. The effects of education and increasing literacy on the tradition are outlined. The interaction between oral and written forms is explored in chapter 2. The role of the imbongi within the religious sphere is included in chapter 3. Xhosa preachers within the independent churches often make use of the styles and techniques associated with oral poetry. Iimbongi who are not necessarily preachers also operate within this context. The relationship between the Congress of South African Trade Unions, the African National Congress and iimbongi has also been researched and forms part of chapters 4, 5, and the epilogue. The modern imbongi is drawn towards powerful organisations offering alternative leadership to many of the traditional chiefs. In the epilogue collected poetry is analysed in the context of Mandela's visit to Transkei in April 1990. Interviews have been conducted with chiefs, iimbongi attached to chiefs as well as those attached to different organisations. Poetry has been collected and analysed. In chapter 5, three case studies of modern iimbongi are included. The problems facing these iimbongi in their different contexts, as well as the power bases from which they draw, are outlined. Finally, an alternative definition of the imbongi is offered in the conclusion
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  • Date Issued: 1991

Topical corticosteroid-induced skin blanching measurement, eye or instrument?

  • Authors: Haigh, John M , Smith, Eric W
  • Date: 1991
  • Language: English
  • Type: Article
  • Identifier: vital:6378 , http://hdl.handle.net/10962/d1006296
  • Description: We have read with interest a recent critique of the human skin blanching assay. We are concerned about the accuracy of statements and the interpretation of results presented in this publication. Having successfully employed this bioassay for over 15 years, and having noted similar, productive usage of this optimized technique reported from laboratories worldwide, the negativism expressed in the critique could dissuade potential researchers from employing this extremely useful assay procedure.
  • Full Text:
  • Date Issued: 1991
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