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Mzeno

Namibia's long road to independence : the Botha era

  • Authors: Ruiters, Michele René
  • Date: 1992
  • Subjects: United Nations -- Namibia , Namibia -- History -- 1946-1990 , Namibia -- Politics and government -- 1946-1990
  • Language: English
  • Type: text , Thesis , Masters , MA
  • Identifier: vital:2754 , http://hdl.handle.net/10962/d1002001
  • Description: This thesis deals with the ten years preceding Namibia's independence in March 1990. It examines the various characters and groups in this process, and how their roles delayed or promoted it. The era of Pieter W. Botha is very significant in that his rule brought many changes to the decision-making process and content of South African foreign policy. This period, 1978 - 1989, marked the formulation of the Total National Strategy in response to the Total Onslaught being waged on South Africa by perceived hostile external forces. Namibia's transition to independence suffered under this military-oriented policy as did the rest of the region. Never before in South Africa's policy-making history had the security sector played such a major role. Regional relations changed subsequent to the policy changes because of the distorted vision the Botha regime had of black-ruled states. Namibia was seen as an important pawn in the Total National Strategy as the last buffer state in Southern Africa protecting South Africa's white minority regime
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  • Date Issued: 1992

Neotype description for the African catfish Clarias Gariepinus (Burchell, 1822) (Pisces: Siluroidei: Clariidae)

  • Authors: Skelton, Paul H (Paul Harvey) , Teugels, Guy G
  • Date: 1992
  • Subjects: Catfishes -- Africa , Clariidae -- Africa
  • Language: English
  • Type: Text
  • Identifier: vital:14995 , http://hdl.handle.net/10962/d1019675 , ISBN 0-86810-231-8 , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 56
  • Description: A neotype for Clarias gariepinus (Burchell, 1822) is designated and described. Data from 41 specimens from the type locality are also presented. The geographical distribution of the species is discussed. , Rhodes University Libraries (Digitisation)
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  • Date Issued: 1992

Neuropharmacological interactions in the rat pineal gland a study of antidepressant drugs

  • Authors: Banoo, Shabir
  • Date: 1992
  • Subjects: Antidepressants -- Research , Pineal gland -- Research
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:3744 , http://hdl.handle.net/10962/d1003222 , Antidepressants -- Research , Pineal gland -- Research
  • Description: The rat pineal gland provides a convenient model for investigating nor adrenergic receptor neurotransmission and the effects of various drugs on these processes in health and disease. The effect of a variety of antidepressant drugs on rat pineal gland function following acute and chronic administration is described. Antidepressants from several different classes increase melatonin synthesis in rat pineal gland cultures when administered acutely. This effect appears to be mediated by noradrenaline acting on postsynaptic β-adrenoceptors. Activation of these receptors, in turn, activates the enzyme serotonin N-acetyltransferase via a cyclic adenosine monophosphate (cAMP) second messenger system. Serotonin N-acetyltransferase catalyses the rate-limiting conversion of serotonin to melatonin. Blockade of postsynaptic β-adrenoceptors prevents the antidepressant-induced increase in melatonin synthesis. The possibility that atypical antidepressants as well as those that selectively inhibit serotonin reuptake may increase melatonin synthesis via a β-adrenoceptor mechanism is discussed. In contrast, however, antidepressants from different classes have variable effects on rat pineal gland function when administered repeatedly. Chronic treatment with antidepressants that selectively inhibit noradrenaline reuptake appear to down-regulate the β-adrenoceptor system while, simultaneously, increasing melatonin output. Atypical antidepressants and those that selectively inhibit serotonin reuptake appear to be without these effects when administered repeatedly. The pineal gland of normal rats may therefore not represent a suitable model for evaluating the biochemical effects of chronic antidepressant treatment. In an attempt to investigatc pineal gland function in rats with "model depression" , antidepressants were administered to chronically reserpinized rats. Treatment with reserpine produced an increase in the density of pineal β-adrenoceptors. In addition, pineal cyclic AMP accumulation and N-acetyltransferase activity were increased in reserpinized rats following exogenous catecholamine stimulation. Reserpine, by depleting intraneuronal catecholamine stores, prevented the nocturnal induction of N-acetyltransferase activity and reduced the synthesis of melatonin in pineal gland cultures. A variety of antidepressants, irrespective of their acute pharmacological actions, reversed these effects when administered chronically to resepinized rats. Acute antidepressant administration was not associated with a reversal of the reserpine-induced effects. These findings provide additional evidence against the hypothesis that antidepressant drugs act by reducing noradrenergic neurotransmission and casts doubt on the importance of β-adrenoceptor down-regulation in the mechanism of antidepressant action. The possibility that the pineal gland of the reserpinized rat may represent an alternative model for evaluating antidepressant therapies is discussed.
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  • Date Issued: 1992

Ngalanga 1st movement

Ngalanga 2nd movements

Ngalanga 3rd movement

Ngalanga 4th movement

Ngalanga 5th movement

Nickel sulphide mineralization associated with Archean komatiites

  • Authors: Lane, Monica Leonie
  • Date: 1992
  • Subjects: Nickel sulfide , Geology, Stratigraphic -- Archaean
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4982 , http://hdl.handle.net/10962/d1005594 , Nickel sulfide , Geology, Stratigraphic -- Archaean
  • Description: The distribution of Archean Nickel sulphide deposits reflects tectonic controls operating during the evolution of the granitoid greenstone terrains. Important deposits of komatiitic-affinity are concentrated within, and adjacent to, younger (∼2.7 Ga), rift-related greenstone belts (e.g. Canada, Western Australia and Zimababwe). Two important classes of Archean Nickel sulphide deposits exist, formerly known as "Dunitic" and "Peridotitic", these are now referred to as Group I and Group II deposits, based on their characteristic structure and composition. Mineralization varies from massive and matrix to disseminated, and is nearly always concentrated at the base of the host unit. Primary ores have a relatively simple mineralogy, dominated by pyrrhotite-pentlandite-pyrite, and to a lesser degree millerite. Metamorphic grades tend to range from prehnite-pumpellyite facies through to lower and upper amphibolite facies. Genesis of Group I and II deposits is explained by the eruption of komatiites into rift-phase greenstone belts, as channelized flows, which assimilated variable amounts of footwall rocks during emplacement. Sulphide saturation was dependent on the mode of emplacement and, the amount of sulphidic sediments that became assimilated prior to crystallization. This possibly accounts for variations in ore tenor. The Six Mile Deposit (SMD) in Western Australia, is an adcumulate body of the Group IIB-type, exhibiting disseminated mineralization. The ore has been "upgraded" due to hydration and serpentinization. A profound weathering sequence exists, which was subsequently utilized during initial exploration. Exploration techniques has been focused on Western Australia, as it is here that the most innovative ideas have emerged.
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  • Date Issued: 1992

Observing and describing textual "reality": a critique of the claims to objective reality and authentication in new critical and structuralist literary theory, seen against a background of Feyerabend's ideas concerning paradigms, dominance and ideology

  • Authors: Masters, Kenneth Andrew
  • Date: 1992
  • Subjects: Feyerabend, Paul, 1924-1994 , Criticism , Structuralism (Literary analysis) , Science and the arts , Reality , Objectivity
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2247 , http://hdl.handle.net/10962/d1002290 , Feyerabend, Paul, 1924-1994 , Criticism , Structuralism (Literary analysis) , Science and the arts , Reality , Objectivity
  • Description: This thesis sets out to examine the claims to objective reality and authentication in New critical and Structuralist literary theories, concentrating on their claims to "objectivity" and "scientific validity." It examines the nature of these claims in the light of the original ideas proposed by some of the major New critics and structuralists in the development of their respective "sciences" of literary theory. Taking direction from the nature of reality and objectivity shown by the theorists, the thesis then attempts an assessment of the validity of some of the original perceptions and presuppositions concerning scientific objectivity and reality. It proposes that inconsistencies within the literary theories resulted from the theorists' inability to grasp the complexity and fluctuating nature of the borrowed terminology and principles that they were using. It does so by taking a closer look at the development of some of the more influential physical theories and the philosophical ideas raised by these developments. It then uses Feyerabend's work on paradigms, dominance and ideology to attempt an assessment of the reasons for the literary theorists' perceptions and presuppositions regarding objectivity and reality. This amounts to accounting for the specific scientific models chosen as bases, and also to accounting for the desire for the "scientific approach" at all. Its conclusions give an indication of the extent to which these original errors contributed to the theories' necessary adaptations of perspective and eventual loss of influence, and emphasises the need for the total understanding of concepts in one field by researchers in other fields, especially if those concepts are to be used by the researchers with any degree of precision.
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  • Date Issued: 1992

Opaqueness to the light of understanding: an investigation into some of the difficulties experienced by a sample of Transkeian matriculants with the components of the concept of chemical equilibrium

  • Authors: Mammen, Kuttickattu John
  • Date: 1992
  • Subjects: Chemical equilibrium Physical sciences -- Study and teaching (Secondary) -- South Africa -- Transkei Black people -- Education -- South Africa
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1680 , http://hdl.handle.net/10962/d1003563
  • Description: The purpose of the study was to collect and collate information pertaining to common misconceptions of components of the concept of chemical equilibrium amongst a sample of Transkeian matriculants. 'Equilibrium' is a fundamental concept in physics and chemistry and 'chemical equilibrium' is an important chemistry topic in both the higher grade and standard grade South African matriculation physical science syllabuses. In recent years, South African teachers have identified chemical equilibrium as the most difficult section of the matric physical science syllabus for both teachers and pupils. It has been shown that teachers themselves lack understanding of the basic concepts underlying chemical equilibrium. Constructivist learning theories arise out of research in cognitive psychology. These theories conceive of cognitive development as the assimilation and accommodation of new ideas into extant, dynamic cognitive structures. An inference from the theories is that a study of the preconceptions and/or misconceptions held by pupils before they are exposed to instruction would enable teachers to avoid generating or reinforcing misconceptions. Hence teachers could also take deliberate steps to eradicate those already existing. The sample consisted of 112 Transkeian matriculants from four government senior secondary schools in the Southern Transkei. All were taking physical science. The test consisted of a 40 item multiple choice battery. Each question had three distracters and the options were randomized to avoid patterns and hence guessing. Questions dealing with closely associated concepts were grouped in the paper but no indication of this was given in the paper. The questions are analyzed singly. A brief introduction and outline of the theory on which the group of questions was based is given in each case. The analysis makes use of the frequency of choice of all options, discrimination indices, although they were generally low and item difficulties. The intent in each analysis is to identify the possible misconception(s) underlying wrong answers. Finally conclusions based on the discussion are drawn and recommendations for teaching and further research made.
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  • Date Issued: 1992
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