Sulphide-enhanced hydrolysis of primary sewage sludge : implications for the bioremediation of sulphate-enriched wastewaters
- Authors: Whittington-Jones, Kevin John
- Date: 2000
- Subjects: Bioremediation Sewage sludge Hydrolysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3910 , http://hdl.handle.net/10962/d1003969
- Description: The potential application of sulphate reducing bacteria for the bioremediation of acid mine drainage has already been recognised, and offers significant financial advantages over conventional chemical treatment approaches. Although the technology has been demonstrated successfully on both small- and large-scale, it’s extensive implementation has been constrained by the provision of suitable and cost effective electron donor and carbon sources. Primary sewage sludge is readily available in large quantities, but the slow rate of solubilization and low yield of soluble products do not apparently favour its use for this application. A number of pre-treatment steps have been introduced in an attempt to improve the yield and rates under methanogenic conditions. However, although early work suggested that degradation of lignocellulose and proteins may be more rapid under sulphate reducing conditions, the fate of primary sewage sludge under these conditions has been ignored. It was proposed that by combining the hydrolysis of primary sewage sludge and biological sulphate reduction, in a settling sludge bed, both processes would be enhanced. The aim of this study was to test this hypothesis on laboratory- and pilot-scale, and attempt to elucidate the underlying mechanism involved. The solubilization of primary sewage sludge was enhanced in the presence of sulphate reduction in continuous laboratory-scale reactors. Particulate matter accumulated in the bed of non-sulphidogenic systems, but not in sulphidogenic ones. This was attributed to increased solubilization and the smaller average floc size in the latter. Solubilization occurred within the settling sludge bed of the reactors, and offered a possible explanation for the better performance of the multiple- over single-stage reactor. A pilot-scale Falling Sludge Bed Reactor was constructed at Grootvlei Gold Mine, Springs, South Africa, and resulted in the solubilization of more than 70% of the influent primary sewage sludge. The system was also found to be highly resilient to severe perturbations, and returned rapidly to steady-state. Flask studies revealed that the hydrolysis of both proteins and complex carbohydrates was accelerated in the presence of biological sulphate reduction or sulphide. A study of the enzymology of sludge digestion revealed that sulphate reduction had little direct effect on the activity of the hydrolytic enzymes, but that reactor design was critical in the prevention of washout of these enzymes. Finally, a descriptive model was developed to explain the enhanced hydrolysis of primary sewage sludge. The model incorporated the effect of sulphidogenesis on floc fracture and reflocculation, and likely implications for mass transfer limitations.
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- Date Issued: 2000
An investigation of learners' perceptions of homework in relation to the learning of mathematics : case studies in the northern townships of Port Elizabeth
- Authors: Wendt, Gabriele Erika
- Date: 2000
- Subjects: Homework -- South Africa -- Port Elizabeth Mathematics -- Study and teaching -- South Africa -- Port Elizabeth Mathematics -- Study and teaching -- South Africa -- Case studies Education and state -- South Africa Education -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1635 , http://hdl.handle.net/10962/d1003517
- Description: Matriculation pass rates in South Africa, especially in Mathematics, have been poor. The literature and personal experience suggests that a problem with homework may be a factor in this. In order to discover how Port Elizabeth learners from ex-DET schools perceived and experienced Mathematics homework, and the nature of such homework, ten case studies of Grade 11 learners were done. While conducting and analyzing the case studies, a pattern emerged from the findings, which together with some new questions, needed to be explored on a larger sample population. In order to do this and to be able to generalize the findings, four follow-up studies in the form of surveys on Mathematics homework were conducted at nine schools. These studies involved a learner questionnaire, a teacher questionnaire, the timing of learners as they did set Mathematical problems and the analysis of common errors made by the learners while doing the problems. The findings revealed that learners received too little homework too infrequently and did it inefficiently and ineffectively. The learners worked too slowly, did not complete the homework, left out the difficult problems and made numerous unnecessary mistakes. However, most of the learners claimed to have enough time available to do their homework and spent approximately one hour on Mathematics homework when it had been assigned. Many of the misconceptions and the resultant errors originated from work that should have been well covered in previous grades. However, parts of the syllabi were omitted in previous grades and completion of the syllabus and homework was only seriously considered in Grade 12. Some implications of the findings for educational practice and further research are discussed.
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- Date Issued: 2000
Synthetic and analytical studies of biomimetic metal complexes
- Authors: Wellington, Kevin Wayne
- Date: 2000
- Subjects: Biomimetics Metal complexes Metalloenzymes Metal ions Ligands
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4377 , http://hdl.handle.net/10962/d1005042
- Description: Several series of novel diamido, diamino and diimino ligands containing different spacers and heterocyclic donors have been synthesised. The spacers include the flexible biphenyl, the rigid 1,1 O-phenanthroline and various acyclic moieties, while the heterocyclic donors comprise pyridine, imidazole or benzimidazole groups. These ligands have been designed to complex copper and act as biomimetic models of the active site of the enzyme, tyrosinase, and their complexes with copper, cobalt, nickel and platinum have been analysed using microanalytical, IR, UV-Visible and cyclic voltammetric techniques. Attempted reduction of the biphenyl-based diimino ligands resulted in an unexpected intramolecular cyclisation affording azepine derivatives, the structures of which were elucidated with the aid of single crystal X-ray analysis of cobalt and nickel complexes. Computer modelling methods have been used to explore the conformational options of the copper complexes, and to assess the accessibility of the dinuclear copper site to substrate molecules. Computer modelling has also been used, in conjunction with the available analytical data, to visualise the possible structures of selected ligands and complexes. The copper complexes, although predominantly polymeric, were evaluated as biomimetic catalysts using 3,5-di-t-butylphenol and 3,5-di-t-butylcatechol as substrates. Some of the complexes clearly displayed biomimetic potential, exhibiting both phenolase and catecholase activity.
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- Date Issued: 2000
A history of the South African police in Port Elizabeth, 1913-1956
- Authors: Watson, Kelvin Innes
- Date: 2000
- Subjects: Police -- South Africa -- Eastern Cape South African Police -- South Africa -- Port Elizabeth -- History Police -- South Africa -- Port Elizabeth -- History
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2570 , http://hdl.handle.net/10962/d1002423
- Description: This thesis investigates the policing activities of the South African Police (SAP) in Port Elizabeth from the formation of the SAP in 1913 to the creation of two separate police districts in the city in 1956. It begins with the recruitment and training of police personnel, outlining the difficulty in obtaining sufficient white recruits for most of the period while at the same time stressing the ease with which the Force was able to obtain black recruits. The preponderance of Afrikaner policemen serving in Port Elizabeth from the 1920s onwards is made clear, as is the para-military nature of the SAP, which was maintained and reinforced as a result of training methods and the process of socialisation. As state servants, police personnel were expected to serve loyally and obediently a state becoming increasingly repressive towards its black citizens. Generally inadequate conditions of service remained the norm throughout the period yet the SAP’s commitment to the state never wavered, bar one isolated, short-lived incidence. The administration and functioning of policing in Port Elizabeth is explored by focussing on specific organisational features pertinent to the city and the changes wrought by the police hierarchy to deal with the city’s demographic and spatial expansion. The SAP tended to employ three different forms of policing in the city as a result of its apartheid-driven agenda which compelled it to differentiate between the various population groups in terms of maintaining law and order. The privileged white community experienced routine, civil policing whereas the black community was policed largely in a socially and politically oppressive manner; this was in line with government policy. On the whole, however, the more brutal and sinister nature of policing was yet to come to the fore although this thesis does point towards the increasingly repressive nature of policing in South Africa during the apartheid era.
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- Date Issued: 2000
The growth and reproduction of Patella granularis (Mollusca : patellogastropoda) on the south-east coast of South Africa
- Authors: Vat, Laura Suzanne
- Date: 2000
- Subjects: Patellidae Limpets -- South Africa Mollusks -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5702 , http://hdl.handle.net/10962/d1005388
- Description: Aspects of the biology and ecology of Patella granularis were investigated along a 130km stretch of the south-east coast of South Africa. Distribution, biomass, density and population structure were investigated at seven localities. In addition, a more detailed study of the growth rate and reproductive biology of populations inhabiting three different substrata (aeolianite, quartzitic sandstone and mussel shells) was conducted. The genetic relationships between these three populations was also examined, as was the foraging behaviour of the limpets inhabiting an aeolianite and a quartzitic sandstone shore. Finally, differences in food availability on the different substrata were studied. On the south-east coast, P. granularis has a wide intertidal distribution, occurring from the upper Balanoid zone through to the Cochlear zone, where it is a common inhabitant of mussel shells. The mean shell length of P. granularis was found to decrease down the shore. The largest limpets (46.6 mm shell length) were found on an offshore island in Algoa Bay. At most localities investigated, the sex ratio deviated from a 1:1 ratio with more males than females being recorded on five shores. Both limpet density and biomass were lower on the south-east coast when compared to data published for west coast populations. On the south-east coast, both density and dry biomass were highest in the lower Balanoid zone. Allozyme electrophoresis indicated that P. granularis inhabiting aeolianite, quartzitic sandstone and mussel shells are all part of a single population. Extremely high genetic identity values (0.998), low levels of heterozygosities (0.035 - 0.061), low levels of polymorphisms (25% - 31%) and low FST values (0.021) all suggest that the three populations of P. granularis form a common breeding group, despite the high levels of phenotypic plasticity observed. On all shores, P. granularis was found to grow allometrically, increasing in shell height more rapidly than shell length. Estimation of the growth rate (determined by the Von Bertalanffy growth model) of P. granularis suggested that limpets inhabiting the mussel shells grew more slowly, and attained a smaller maximum size, than those inhabiting both the aeolianite and the quartzite (K = 0.25, 0.32 and 0.33 respectively; 27.12 mm, 31.89 mm and 32.96 mm respectively). Previous work has shown that west coast P. granularis grow more quickly (K = 0.7) and reach a greater size (. 40 mm). Translocation of limpets among sites suggested that limpet size in the mussel beds was spatially constrained. Shell microgrowth bands were deposited tidally, but could not be used for aging limpets due to shell erosion. Limpets from the aeolianite had the greatest reproductive fitness, producing more eggs (.366 000/limpet) than those inhabiting quartzite (.119 500/limpet) or mussel shell limpets (.85 800/limpet). Aeolianite limpets also spawned throughout the year, whereas those from the quartzite and mussel shells spawned twice a year (once in winter and once in summer) although a great deal of interannual variability was observed. The onset of sexual maturity occurred at a similar age in all limpets (1 - 2 years) and is probably genetically entrenched. P. granularis inhabiting both an aeolianite and a quartzitic shore were active during nocturnal low tides. All limpets returned to a home scar after foraging. Whilst foraging, limpets inhabiting the aeolianite shore moved shorter distances (.17 cm) at a slower rate than those from quartzite (.30 cm). Limpets that were translocated from one substratum to the other initially moved similar distances to the source group, but after a maximum period of one week, moved distances that mirrored those moved by the resident limpets. Neither season nor tidal phase influenced the distances foraged. No directionality in foraging was found. Wear of radula teeth, particularly the pluricuspid tooth, was greater in limpets from the quartzite. It is hypothesised that the observed differences in life-history parameters and foraging behaviour of limpets both within the south-east coast and between the west and south-east coasts are related to food abundance. Chlorophyll-a, and hence microalgal biomass, was consistently higher on aeolianite (.2.5 times) than on both quartzite and mussel shells. Estimates of chlorophyll-a were higher (although not significantly) in winter. Previous studies determined that primary productivity is also higher along the west coast. Finally, the lack of evidence for migration of limpets from the low-shore to high-shore in south-east coast P. granularis is discussed. It is suggested that this species settles opportunistically within its physiological tolerances and responds morphologically to localised environmental conditions.
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- Date Issued: 2000
Petrographic and geochemical constraints on the origin and post-depositional history of the Hotazel iron-manganese deposits, Kalahari Manganese Field, South Africa
- Authors: Tsikos, Harilaos
- Date: 2000
- Subjects: Manganese ores -- South Africa Manganese ores -- Geology -- South Africa Iron ores -- Geology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4987 , http://hdl.handle.net/10962/d1005599
- Description: The giant Palaeoproterozoic manganese deposits of the Kalahari manganese field (KMF), Northern Cape Province, South Mrica, have been a world renowned resource of manganese ore for many decades. In recent years, the mineralogical composition, geochemistry and genesis of these deposits have been the objects of many geological investigations, yet their origin remains contentious up to the present day. A characteristic feature of the Kalahari deposits is the intimate association of manganese ore and iron-formation of the Superior-type, in the form of three discrete sedimentary cycles constituting the Hotazel Formation. This striking lithological association is an almost unique feature on a global scale. From that point of view, the present study is effectively the first attempt to shed light on the origin and post-depositional history of the Hotazel succession, using as prime focus the petrographic and geochemical characteristics ofthe host iron-formation. Petrographic and whole-rock geochemical information of iron-formation from the southern parts of the KMF, suggests that the Hotazel iron-formation is almost identical to other iron-formations of the world of similar age and petrological character. The rock exhibits essentially no high-grade metamorphic or low-temperature alteration effects. Mineralogically, it contains abundant chert, magnetite, subordinate amounts of silicate minerals (greenalite, minnesotaite, stilpnomelane) and appreciable concentrations of carbonate constituents in the form of coexisting calcite and ankerite. Such mineralogical composition is indicative of processes occurring in a diagenetic" to burial (up to very low-greenschist facies) metamorphic environment. Bulk-rock geochemical data point towards a simple composition with Si02, total Fe-oxide and CaO being the chief major oxide components. Whole-rock rare-earth element data suggest that the iron-formation precipitated from a water column with chemical signatures comparable to modern, shallow oceanic seawater. The virtual absence of positive Eu anomalies is a feature that compares well with similar data from Neoproterozoic, glaciogenic iron-formations of the Rapitan type, and suggests but only a dilute hydrothermal signal, poten!ially derived from distal submarine volcanic activity. Carbon and oxygen isotope data from iron-formation and Mn-bearing carbonates as well as overlying ferriferous limestone of the Mooidraai Formation, compare well with the literature. The former exhibit variable depletion relative to seawater in terms of both BC and 180, while the latter have signatures comparable to normal marine bicarbonate. Isotopic variations appear to be related to fluctuations in the amount of co-precipitated marine carbonate, in conjunction with processes of coupled organic matter oxidation - FelMn reduction in the diagenetic environment. Oxygen isotope data from quartz-magnetite-calcite triplets suggest that crystallisation took place under open-system conditions, with magnetite being the most susceptible phase in terms of fluid-rock isotopic exchange. Data also suggest that the calcite-magnetite pair may constitute a more reliable geothermometer than the quartz-magnetite one, mainly due to the interlinked diagenetic histories between calcite and magnetite. Iron-formation from the northern parts of the KMF can by categorised into three main classes, namely pristine, altered and oxidised. Pristine iron-formation is identical to the one seen in the southernmost parts of the field. Altered iron-formation corresponds to a carbonate-free derivative of intense oxidation and leaching processes at the expense ofpristine iron-formation, and contains almost exclusively binary quartz-hematite mixtures. The rock appears to have lost essentially its entire pre-existing carbonate-related components (i.e., Ca, Mg, Sr, most Mn and Ba) and displays residual enrichments in elements such as Cr, Th, V, Ni and Pb, which would have behaved as immobile constituents during low-temperature alteration. The low temperature origin of altered iron-formation is supported by oxygen isotope data from quartz-hematite pairs which indicate that isotopically light hematite would have derived from oxidation of magneftte and other ferroussilicate compounds in the presence of a low-temperature meteoric fluid, while quartz would have remained isotopically unchanged. Occasional occurrences of acmite-hematite assemblages suggest localised metasomatic processes related to the action ofNaCI-rich fluids at the expense of altered iron-formation. The conditions of acmite genesis are very poorly constrained due to the very broad stability limits of the mineral in environments ranging from magmatic to surface-related. Oxidised iron-formation constitutes a distinct rock-type and shares common attributes with both the pristine and the altered iron-formation. The rock contains hematite as an important constituent while the amount of magnetite is substantially reduced. With regard to carbonate nlinerals, calcite contents are clearly very low or absent, having being replaced in most instances by a single, Mgenriched, dolomite/ankerite:type species. Oxidised iron-formation contains somewhat higher amounts of iron and reduced amounts of Sr and Ba relative to pristine iron-formation, whereas enrichments in elements such as Ni, Th, Pb, Cr, and V are seen, similar to altered iron-formation. Oxidised iron-formation appears to have originated from processes of dissolution-mobilisationreprecipitation of solutes derived primarily from leaching that produced altered iron-formation. It is proposed that the Hotazel iron-formation and associated manganese deposits were formed as a result of episodic sea-level fluctuations in a stratified depositional environment that gradually evolved into a shallow carbonate platform. A critical parameter in the development of manganese sediment may include regional climatic patterns related to a glacial event (Makganyene diamictite) prior to deposition of the Hotazel strata. This suggestion draws parallels with processes that are believed to have led to the formation of worldwide iron-formations and associated manganese deposits subsequent to Neoproterozoic episodes of glaciation. Submarine volcanism related to the underlying Ongeluk lavas appears to have had very little (if any) metallogenic significance, while evidence for a sudden rise in the oxygen contents of the atmosphere and ambient waters is lacking. With regard to later alteration processes, combination of geological and geochemical data point towards the potential influence of surface weathering prior to deposition of rocks of the unconformably overlying Olifantshoek Supergroup, possibly coupled with fault- and/or thrustcontrolled fluid-flow and leaching of the Hotazel succession during post-Olifantshoek times.
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- Date Issued: 2000
The psychological role of homoeroticism in the spiritual growth of priests: a study of individuation processes and homoerotic sexualities
- Authors: Taute, Harold Graeme
- Date: 2000
- Subjects: Homosexuality -- Psychological aspects Homosexuality -- Religious aspects -- Christianity
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3069 , http://hdl.handle.net/10962/d1002578
- Description: The study explored the psychological role of homoeroticism in the spiritual growth of priests, using Grounded Theory and James Fowler’s stages of faith development as the basis for the research methodology. Three Anglican priests were interviewed using a semi-structured interview format. The research interview combined Fowler’s Faith Development Interview Guide and a semi-structured interview in order to ascertain the priests’ level of spiritual development, as well as to explore their experience of the homoerotic component to their sexuality, and its influence on their spiritual growth. The interviews and iterative analysis focussed on four major questions: (1) Are priests who experience and actively work at integrating the homoerotic aspect to themselves assisted thereby in their spiritual growth, and if so, how might this be accounted for?; (2) Following Fowler’s model of spiritual development, what processes characterise each priest’s approach to meaning-creation in their lives?; (3) Following Fowler’s model, can the psychological work of engaging with and accepting homoeroticism be conceived of as serving an initiatory function in the emergence of new processes of meaning-creation?; (4) What role does homoeroticism serve in the spiritual growth of priests? The interpretative phase consisted of three stages. A grounded theory analysis of each interview was undertaken, developing a model for understanding the role of homoeroticism in spiritual growth. In the second stage, the priest’s level of spiritual development was ascertained, using Fowler’s Faith Development Guide. The third stage linked each participant’s level of spiritual development (in Fowler’s terms) with their core stories regarding experiences, meanings, and roles of homoeroticism. Finally, an integrative theory of the role of homoeroticism in spiritual growth was developed, using Jungian and post-Jungian theory as a basis for the discussion. The results suggested that homoeroticism did not play any role in spiritual growth and individuation separate to the manner in which it was experienced as having been constructed by society and the Church, and separate to the manner in which each priest in the study expressed, experienced, or engaged with it. In this context the experience of homoeroticism appeared to play a diversity of roles, including representing the collective and personal shadow, the archetypal anima/animus, the archetypal puer/senex constellation, the transcendent function, and thereby, as an expression of these roles, contribute to the emergence of new processes of meaning-creation in the spiritual growth and individuation of priests.
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- Date Issued: 2000
The protein requirements of the South African abalone, Haliotis midae
- Authors: Shipton, Thomas A
- Date: 2000
- Subjects: Abalones -- Nutrition Abalones -- Digestion
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5314 , http://hdl.handle.net/10962/d1005159
- Description: The potential to reduce feed formulation costs by the replacement of existing proteinsources in artificial feeds for Haliotis midae was assessed. A comparison between the efficacy of the direct method and chromic oxide marker techniques in determining apparent protein digestibility coefficients, revealed that while the former was not a suitable methodology for use with this species, the latter produced replicable and reliable results. It was established that the chromic oxide marker is inert, is not absorbed by the abalone, does not interfere with the digestive processes and moves through the intestine at the same rate to the protein. However, as this method was time consuming and expensive to implement, a multienzyme pH-stat in vitro protein digestibility technique using a three enzyme system was employed to rapidly assess the protein quality of 34 protein sources. The efficacy of the technique was established by correlating the in vitro digestibility estimates with in vivo digestibility coefficients obtained using the chromic oxide marker technique. The highest degree of in vivo predictability was attained when protein sources were separated according to origin, and significant correlations between either animal (r²=0.89, P<0.004) or plant (r²=0.79, P<0.04) protein sources were found. The effect of animal size on the qualitative protein requirements of two size classes of H.midae was assessed by feeding 12 isonitrogenous and isoenergetic single protein diets to juvenile and young adult animals (10-20 and 40-50mm shell length). The criteria for protein source selection were their bioavailability as determined using the pH-stat in vitro digestibility technique, and their cost and availability within South Africa. The protein sources identified for the trial comprised four fishmeals, casein, spirulina, abalone viscera silage, brewery waste, torula yeast, carcass, sunflower and cotton meals. The results indicated that in terms of growth and feed efficiency, the fishmeals and spirulina were the most suitable candidates as primary protein sources in formulated feeds for H.midae, and with the exceptions of the carcass meal and brewery waste, the remaining protein sources demonstrated promise as partial primary protein source replacements. The smaller size class of abalone displayed significantly reduced growth, feed and protein efficiency than their larger counterparts. In terms of feed conversion and growth response, two-way analysis of variance revealed significant interactions between protein source and animal size, suggesting that qualitative differences exist between the dietary protein requirements of the juvenile and young adult abalone. The commercial implication of thisfinding was discussed. An evaluation was undertaken to determine the effects of the partial and total replacement of dietary fishmeal with selected plant protein sources on growth and nutritional indices of juvenile H.midae. A commercial “Abfeed” formulation in which 100% of the protein component comprised LT-fishmeal was employed as a control. Fifteen isonitrogenous experimental diets were formulated in which the LT fishmeal was substituted at either 10, 15, 30, 50, 75 or 100% with either spirulina, semolina, ground maize, torula yeast, soya, sunflower or corn gluten meals or combinations thereof. No significant differences were found in the growth rates between the control diet and those diets in which 30% of the fishmeal component had been replaced by either soya, sunflower meal, or torula yeast. In addition, 50% of the fishmeal component could be substituted with either soya meal or spirulina without affecting growth. Replacement of either 75 or 100% of the fishmeal had a significant negative affect on growth. Pearson product moment correlations between dietary lysine levels and either growth rates or protein efficiency ratios revealed positive correlations (r=0.77, P=0.0005; r=0.52, P=0.04 respectively) suggesting that lysine may have been the first limiting amino acid in these diets. Carcass analysis revealed that dietary protein source had no significant effect on body composition. An assessment of the dietary arginine requirement of juvenile H.midae using whole proteins to supply graded levels of dietary arginine did not promote a growth response. It was concluded that arginine is probably not the first limiting amino acid in formulated feeds for H.midae. An assessment of the dietary lysine requirement of juvenile H.midae using two micro-encapsulation techniques (gelatin/acacia colloid or cellulose acetate phthalate) was not successful. The efficacy of the encapsulation techniques were established and an assessment of the degree of lysine supplementation undertaken. Failure of the crystalline lysine enriched diets to promote growth suggests that the prospects for using crystalline amino acids in essential amino acid requirement studies in H.midae is low. The results of the present study indicate that the prospects for replacing fishmeal with cheaper alternative protein sources in artificial feeds for H.midae is promising. Furthermore, while the technical difficulties such as the determination of the essential amino acid requirements of the abalone precluded the application of “least cost” programming, the prospects for its future application are promising.
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- Date Issued: 2000
The phenomenology of the anorexic body
- Authors: Shapiro, Joel
- Date: 2000
- Subjects: Anorexia nervosa Eating disorders Anorexia nervosa -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3053 , http://hdl.handle.net/10962/d1002562
- Description: The purpose of the study is to articulate the phenomenology of the anorexic body. In order to describe the complex meaning of the anorexic body, the present research adopts the qualitative and exploratory approach of Seidman's (1991) in-depth phenomenologically based interviewing method. This involves a series of three separate interviews, with three research participants who have had personal experience of anorexia. The method of data analysis used is essentially on editing style of analysis (Miller and Crabtree, 1992) and is based on a hybrid of the grounded theory approach of Glaser and Strauss (1967) and Heidegger's (1927) ontological hermeneutics to form what Addison (1992) calls grounded interpretive research. Anorexic embodiment is conceptualised as precipitating a fundamental disturbance between the interactions of embodied consciousness and the world. The body is no longer taken-for-granted, and becomes an object for scrutiny. As an object, the body is experienced as a thing exterior to the self, and this awareness contributes to the sense of qisorder which permeates anorexic embodiment. Bodily intentionality is frustrated when the sphere of bodily actions and habitual acts become circumscribed. The character of lived temporality and lived spatiality are also effected with the anorexic's focus on the now, ushering in a spatiality of the here. These findings indicate that anorexic embodiment is experienced primarily as a disruption of the 'lived body' rather than that of the biological body. The prevailing discourses of anorexic embodiment are shown to be split between the naturalized discourses that provide a model of the body that is biologically determined and ahistorical, and the denaturalized discourses that provide a model of the body that is culturally constructed and lacks embodied givenness. It is argued that Merleau-Ponty's phenomenology of the body offers a renaturalization of the body that overcomes the nature/culture dichotomy of the naturalized and denaturalized discourses, thereby providing a solid foundation that more directly addresses the phenomenology of the anorexic body. The theoretical and treatment implications of Merleau-Ponty's renaturalization of the anorexic body are highlighted, and suggestions for further research are presented.
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- Date Issued: 2000
In time of plague : the Basotho and the rinderpest, 1896-8
- Authors: Phoofolo, Pule
- Date: 2000
- Subjects: Rinderpest -- Lesotho -- History Epidemics -- Africa -- History Livestock -- Diseases -- Africa Sotho (African people) -- Social life and customs Lesotho -- History
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2553 , http://hdl.handle.net/10962/d1002405
- Description: Rinderpest, the most dreaded bovine plague, struck the cattle of the BaSotho in British Basutoland early in 1897. By December the murrain had spent itself, having reduced the cattle population by half As it did so, the rinderpest claimed the primary historical significance of an epidemic. By sharpening behaviour and illuminating latent or developing tendencies, the rinderpest helped to reveal the nooks and crannies of contemporary historical processes that would have otherwise eluded historical visibility. This thesis brings out the complexities and ambiguities surrounding the epidemic. It uses the crisis occasioned by the panzootic in its multifaceted manifestations as a prism through which we might view the complex aspects of contemporary historical processes. It goes beyond the narrow limits of the crisis itself to discerning the broader and wider historical patterns that the rinderpest helped to highlight.
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- Date Issued: 2000
Photocatalytic reactions of metal diphthalocyanine complexes
- Authors: Nensala, Ngudiankama
- Date: 2000
- Subjects: Metal complexes Electrochemistry Photochemistry Pentachlorophenol
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4328 , http://hdl.handle.net/10962/d1004989
- Description: Photocatalytic reactions of tin diphthalocyanine, Sn ^IVPc₂ and anionic form of Nd^III, Dy^III, Eu^III, Tm^III and Lu^III diphthalocyanine complexes ( [Pc(-2)Nd^IIIpc(-2)]⁻ , [Pc(-2)Dy^IIIPc(-2)]⁻ , [Pc(-2)Eu^IIIPc(-2)⁻, [Pc(-2)Tm^IIlPc(-2)r and [Pc(-2)LuIIIpc(-2)]⁻ respectively) in the presence of CH₂CI₂, S0₂, pentachlorophenol (PCP), 4-chlorophenol (4-Cp) and thionyl chloride have been studied. Photoreactions involving lanthanide diphthalocyanines, filtered and unfiltered radiations were employed, whereas for photoreactions involving tin diphthalocyanine, only unfiltered radiation was employed. For lanthanide diphthalocyanine complexes, LnPce-, the photosensitization power increases with the decrease of the lanthanide ionic radii, implying that the photocatalytic activity of LnPc₂⁻ complexes is associated with the π-π interaction between both phthalocyanine rings. Thus, LuPc₂⁻ is a better photocatalyst than other lanthanide diphthalocyanine complexes. Photolysis ofSnPc₂ in an acetonitrile/dichloromethane solvent mixture, using unfiltered radiation from a tungsten lamp, results in the one-electron oxidation of this species to [Pc( -2 )Sn(IV)Pc(-1)]⁻. The relative quantum yields for the disappearance of SnPc₂ are in the order of 10⁻¹. The photoreaction of SnPc₂ is preceded by excitation to nπ* excited states, before been ,quenched by CH₂CI₂. The one-electron oxidation species, [Pc(-2)Sn(lV)pc(-1)]⁻ was also formed during the photolysis of SnPc₂ in dichloromethane containing S0₂, and with quantum yields of order of 10⁻³. Visible photolysis of [Pc( -2)Nd^IIIpc(-2)]⁻, [Pc(-2)Dy^IIIPc(-2)]⁻ and [Pc(-2)Lu^IIIpc(-2)]⁻ in N,N. dimethylformamide (DMF)/dichloromethane solvent mixture containing SO₂, results in the formation of the one-electron oxidation species, Pc(-2 )Nd^IIIpc(-1), Pc( -2) Dyi^IIIPc(-1) and Pc(-2)Lu^IIIpc(-1), respectively. The relative quantum yields are in the order of 10². The photoreactions are preceded by population of the excited triplet state,³π-π* [ LnPc₂]⁻ complex, before exchanging an electron with S0₂. The one-electron oxidation species of Dy^III and Lu^III diphthalocyanine complexes have also been formed from visible photolysis of [Pc(-2 )Dy^IIIPc(-2)]⁻and [Pc(-2)Lu^IIIpc(-2)]⁻in acetonitrile containing PCP. The PCP is reductively dechlorinated to tetra- and trichlorophenols. The quantum yields for the photosensitization reactions are in the order of 1 0⁻. Photolysis, using visible radiation from 220 W Quartzline lamp, of an aqueous solution of 4-Cp, saturated with oxygen and containing a suspension of solid [Pc(-2)Nd^IIIpc(-2)]⁻, results in the formation of benzoquinone, hydro quinone and 4-chlorocatechol. The quantum yields for the degradation of 4-Cp are in the order of 10⁻. Langmuir-Hinshelwood kinetic model shows the adsorption of 4-chlorophenol onto solid [Pc(-2)Nd^IIIpc(-2)]⁻. Lanthanide diphthalocyanine complexes ([Pc-2)Nd^IIIpc(-2)]⁻. [Pc(-2)Eu^IIIpc(-2)]⁻, (Pc(-2)Tm^IIIpc( -2)]⁻ and (Pc(-2)Lu^IIIpc(-2)]⁻) undergo one or two-electron oxidation in the presence of thionyl chloride. At low concentrations of SOCI₂(<10⁻⁴ mol dm⁻³) the visible yhotolysis of [Pc(-2 )LnPc(-2)]⁻ complexes result in the one-electron oxidation, giving neutral lanthanide diphthalocyanine species, Pc(-2)Ln^IIIpc(-1). The Pc(-2 )LnPc(-I) species undergoes one-electron photooxidation to [Pc(-I )LnPc( -I)]⁻ in dichloromethane and in the presence of SOC₁₂. At large concentrations of SOC₁₂ (>10⁻² mol dm⁻³), direct two-electron oxidation of the (Pc(-2 )LnPc - 2)]⁻ species to (Pc(-1)LnPc(-1)]⁻ occurs. Spectroelectrochemical behaviours of Sn^IVPc₂ have been also studied. The cyclic voltammetry ofSnPc₂ in CH₂CI₂/TBAP show two reduction couples at -0.56 V and -0.89 V versus saturated calomel electrode (SCE) and one oxidation couple at 0.35 V versus SCE. In DMFITEAP system, the reduction couples are observed at -0.44 V and -0.81 V versus SCE whereas the oxidation couple occurred at 0.43 V versus SCE. The oxidation couple corresponds to [Pc(-2 )Sn^IVPc(-2 )]/[Pc(-2)Sn^IVPc( -I)] . and the reduction couples to [Pc(-2)Sn^IVPc( -2 )]/[Pc(-2 )Sn^IVPc( -3 )]⁻ and [Pc(-2)Snl^IVPc( -3)] ⁻/[Pc(-3 )Sn^IVPc(-3)]²⁻, respectively. The electronic absorption spectra of these reduced and oxidized species are reported.
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- Date Issued: 2000
Education for environmental literacy : towards participatory action research in the secondary school science curriculum in Lesotho
- Authors: Mokuku, Tsepo
- Date: 2000
- Subjects: Environmental education -- Lesotho , Science -- Study and teaching (Secondary) -- Lesotho
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1503 , http://hdl.handle.net/10962/d1003385 , Environmental education -- Lesotho , Science -- Study and teaching (Secondary) -- Lesotho
- Description: The dependency of educators in Lesotho on externally developed curriculum theories and concepts is fundamental to issues of relevance of the school curricula. This study set out to develop the meaning of environmental literacy in the context of three secondary schools and to explore appropriate teaching methods for the development of this concept in the science curriculum. The participatory action research process involved a team of four science teachers, including the researcher, in partnership with an environmental centre. We progressively developed the meamng of environmental literacy by monitoring teaching innovations in the classroom, holding meetings and workshops and attending conferences where we shared classroom findings and reflected on our emerging understandings based on classroom experiences. Data collection involved: audio-recording of classroom lessons, interviews with teachers and students, audio-visual recording, classroom observations and students' questionnaires. The research process made apparent the complex nature of the process of clarifying and developing environmental literacy in this context. Classroom actiyities planned to inform the team's understanding of the meaning of environmental literacy and develop appropriate teaching methods encountered constraints associated with the education system and the legacy of colonialism. These contextual constraints crystallised the need for the education system to be transformed in order to make schools more conducive environments for the gevelopment of students' environmental literacy. While initially teachers were reluctant to engage in critical reflection, the research process did encourage the team to revise and expand their understandings of both environmental literacy in the science classroom, and the action research itself. The emerging meaning of environmental literacy in this context and how it may be developed among students does not involve a definition with prescriptive, effective teaching methods, but provides insights and understandings gained by the participants in their engagement with a reflective process of reconslructing meaning. I have come to understand environmental literacy during the study to be a process that should draw strongly on the local knowledge and understandings into the science curriculum, through participatory process-based curriculum development models.
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- Date Issued: 2000
A critical investigation into course development for the preparation of school leaders
- Authors: McFarlane, Johannes
- Date: 2000
- Subjects: Educational leadership Educational leadership -- South Africa Action research in education School principals -- Training of -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1929 , http://hdl.handle.net/10962/d1007596
- Description: Many schools in South Africa suffer from the consequences of bad leadership and management practices. A contributing factor to this problem is the inadequate preparation of school leaders for the wide variety of challenges facing them. This study formed part of a three-year project to develop a preparation programme for school leaders in the Southern Cape area of South Africa. Its aims focussed on the identification of principles for the design of preparation programmes leading to improvements in practice. Twelve teachers and principals participated in the project. They enrolled for a programme in school leadership designed and offered by the University of Port Elizabeth in consultation and cooperation with the Southern Cape Learning Resource Unit in George. Five sources were utilized for the provision of data: - The existing literature on the development of preparation programmes; - The group of twelve participants of the programme; - The four school principals in the group who acted as a focus group; - The staff and certain documents from the schools where these four principals are employed; - Local stakeholders with an interest in the success of the programme. Research methods typical of the interpretive tradition were utilized in orderto arrive at a better understanding of the needs of participants and of those elements of programmes which have the greatest impact on practice. Among the insights to have emerged from the study are the following: - The fact that the preparation of school leaders is a complex and multifaceted process which is enhanced by variety, continuous interaction between presenters and participants, flexibilityt o respond to changing needs and contexts, and an ongoing implementation in and feedback from practice ; - The central role played in the professional and academic growth of participants by individuals and groups around them; - The importance of action research as a tool in the accomplishment of a variety of goals in the preparation of school leaders. The main contributions of this study include: - A framework for the development of preparation programmes, ensuring the inclusion of a wide range of elements enhancing the effectiveness of the course; - A framework for the establishment of professional networks supporting participants in preparation programmes.
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- Date Issued: 2000
An assessment of the monkfish resource of Namibia
- Authors: Maartens, Lima
- Date: 2000
- Subjects: Lophius -- Namibia Lophius
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5231 , http://hdl.handle.net/10962/d1005074
- Description: Two monkfish species are caught off the coast of Namibia. These are Lophius vomerinus Valenciennes (1837) and L. vaillanti Regan (1903). L. vomerinus is the more abundant of the two and contributes approximately 99% to the total Namibian monkfish landings. The Namibian monkfish fishery is one of the largest and most valuable of its kind in the world. Two fishing fleets harvest the resource, viz. the monkfish and sole fleet and the hake directed fleet. In 1998 and 1999, monkfish were also harvested by one gillnet vessel that had an experimental right. In this study, the biology, abundance and exploitation patterns of monkfish were investigated and used as inputs into a stock assessment framework as a contribution towards the development of a management procedure for this species. Ground and sectioned otoliths and sectioned illicia were used to age Lophius vomerinus. The illicia provided more precise estimates of age, and growth was subsequently modelled using these age estimates. Growth in length and weight was best described by the threeparameter specialised von Bertalanffy model as Lt (cm TL) = 72.29 (1-e⁻°·¹⁴⁽t⁺°·³°⁾) and Wt (kg) = 3.96 (1-e⁻°·¹⁸⁽t⁺°·¹°⁾)²·⁹⁹ for males, and Lt (cm TL) = 111.98 (1-e⁻°·°⁸⁽t⁺°·³⁶⁾) and Wt (kg) = 6.92 (1-e⁻°·¹⁸⁽t⁻°·⁶⁴⁾)³·°³ for females. L. vomerinus is a slow-growing species with a life span in excess of 10 years. Reproductive activity was shown to occur throughout the year, with a slight peak during the winter months. The adult sex ratio of fish > 37 cm TL was biased towards females. Length-at-50% sexual maturity was attained at 32.1 cm TL for females and 23.7 cm TL for males. The rate of natural mortality was estimated at 0.15 year⁻¹, while fishing mortality rates during the 1970s, 1980s and 1990s were estimated at 0.01 year⁻¹, 0.04 year⁻¹ and 0.14 year⁻¹, respectively. Gillnetting for monkfish (300 mm stretched mesh) was highly efficient with a moderate bycatch of around 20% during the two years of operation. The main bycatch species were red crab, spider crab, squalid sharks, rays and Cape and Deep-water hake. The mean length of the monkfish caught in gillnets (67 cm TL) was significantly larger than the monkfish landed by the trawlers (38 cm TL) and less than 1% of immature fish were landed. Gillnet catch-per-unit-effort for monkfish fluctuated between 0.03 and 0.67 kg.day⁻¹.50 m net panel⁻¹, with a soak time of between one and sixteen days. More than 50% (by weight) of monkfish landed by monkfish and sole trawlers, consisted of fish below 36 cm TL. There was a significant increase in catches of juvenile monkfish during 1997 and 1998 in comparison to the period 1994 to 1996. Various types of rigid sorting grids were tested to release juvenile monkfish below 32 cm TL. Five grid designs were tested. These included an “Ex-it” grid with horizontal bars spaced at 55 mm, single grids with vertical and horizontal bars spaced at 55 mm and grids with circular openings of 110 and 168 mm in diameter. The most efficient design was the grid with circular openings of 110 cm in diameter, which ensured the escape of 66% of monkfish smaller than 31 cm TL. However, studies need to be undertaken to quantify the survival of released fish and to test the feasibility of using grid sorters on commercial monkfish and sole trawling gear. The monkfish resource was assessed by means of length cohort analyses, the Thompson and Bell predictive model and by way of a deterministic age-structured production modelling approach. The length cohort analysis models were sensitive to the rate of natural mortality and insensitive to changes in the terminal fishing mortality rate. These biases may, however, not be serious provided that estimates of abundance are used to reflect relative changes. Fish ranging between 26 and 59 cm TL are the most heavily exploited. The Thompson and Bell model predicted that the monkfish resource is exploited above MSY -levels and a reduction of approximately 40% in fishing effort would provide a higher yield. Yield-per-recruit ranged between 10 000 and 14 000 tonnes. Results should, however, be treated with caution, as the condition of steady state was not satisfied. The age-structured production model was tuned using trends in catch-per-unit-effort data, estimated by Generalised Linear Modeling, as well as relative abundance indices calculated from hake biomass surveys. The model was found to be sensitive to both the ‘steepness’ parameter h and estimates of natural mortality. The ‘depletion’ level of the monkfish resource is currently estimated to be 49%. Estimated coefficients of variation were high (> 63%) due to the lack of a consistent trend within the abundance indices to tune the model. Overall productivity of the monkfish resource was estimated to be approximately 16%, similar to other southern African demersal resources. Results of the risk analyses suggest that catches in excess of 7 000 tonnes may be unsustainable and that catches of 5 000 or 6 000 tonnes would decrease the risk of stock collapse and possibly lead to a recovery in the stock. Monkfish management strategies were reviewed and these were considered in relation to the results of this study. The following management recommendations were made: to follow the precautionary approach and implement a total allowable catch for monkfish; to implement rigid sorting grids as these would be the most appropriate way in which to reduce catches of juvenile monkfish; to restrict soak time, depth of operation and implement means to reduce ‘ghost fishing’ by gillnetting and finally, to develop a management procedure for Namibian monkfish with the main objective being the sustainable exploitation of the resource.
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- Date Issued: 2000
Morphological development in the interlanguage of English learners of Xhosa
- Authors: Hobson, Carol Bonnin
- Date: 2000
- Subjects: Grammar, Comparative and general -- Morphology Xhosa language -- Foreign speakers Xhosa language -- Morphology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2348 , http://hdl.handle.net/10962/d1002630
- Description: This study investigates the development of morphology in the interlanguage of English learners of Xhosa. A quasi-longitudinal research design is used to trace development in the oral interlanguage of six learners of Xhosa for a period of eight months. The elicitation tasks employed range from fairly unstructured conversation tasks to highly structured sentence-manipulation tasks. The learners have varying levels of competence at the beginning of the study and they are exposed to input mainly in formal contexts of learning. One of the aims of the study is to investigate whether the features of interlanguage identified in other studies appear in the learner language in this study. Most other studies discussed in the literature have investigated the features of the interlanguage produced by learners of analytic and inflectional languages. However, this study analyses the interlanguage of learners of an agglutinative language. Studies of other languages have concluded that learners do not use inflectional or agreement morphology at early stages of development and this conclusion is tested for learners of an agglutinative language in this study. Since agreement and inflectional morphology play a central role in conveying meaning in Xhosa, it is found that learners use morphology from the beginning of the learning process. Although forms may be used incorrectly and the functions of forms may be restricted, morphemes appear in the interlanguage of learners of this study earlier than other studies predict. One of the characteristics of early interlanguage and an early form of learner language called the Basic Variety (Klein & Perdue 1997) is the lack of morphology, but this feature proves to be inadequate as a measure of early development in the interlanguage of learners of a language such as Xhosa. This study concludes, therefore, that the presence of morphology in the interlanguage of learners of Xhosa cannot be an indicator of advanced language development.
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- Date Issued: 2000
An analysis of the effects of marriage, divorce and death on the child maintenance obligation in South African law with some comparative perspectives
- Authors: Clark, Brigitte
- Date: 2000
- Subjects: Child support -- Law and legislation -- South Africa Divorce -- South Africa Marriage -- South Africa Death
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3669 , http://hdl.handle.net/10962/d1003184
- Description: This thesis analyses the law of child maintenance in South Africa with particular reference to the effects of marriage, death and divorce on such an obligation. In the introductory section, the types of South African family are demographically and statistically sketched, from a socio-legal perspective with some reliance on interdisciplinary research to assess the prevalence of the AID/HIV epidemic in South Africa, and the effects of poverty and ageing on the incidence of marriage and death. In the second part of the thesis, the parental child maintenance obligation is analysed in the common law context. The effects of serial marriage and arificial conception are also analysed with regard to their effect on the concept of biological parent. The nature and definition of parenthood is examined and the diverse and fluid nature of parenthood in South African society is stressed, particularly in relation to children's welfare. One of the aims of the thesis is to indicate how parenthood refers to a fluid set of social practices which are both biologically and culturally situated and thus have a complex effect on the maintenance obligation. The procedural problems of enforcement are also analysed in the light of recent amendments to the law in terms of the Maintenance Act 99 of 1998 (not yet in force) and some further proposals for reform in this area are proposed. The third part of the thesis examines the state obligation to maintain children, especially in the light of the state's commitments to children in terms of the Constitution of the Republic of South Africa Act (l08 of 1996) and its international commitments in terms of the United Nations Convention on the Rights of the Child which was ratified by the South African government on 16 June 1995. In the fourth part of the thesis, there is some comparative analysis, firstly, of the procedural law reforms proposed in Namibia as a result of detailed research done there. Secondly, alternative methods of assessing and enforcing child maintenance obligations in Australia and England are examined and briefly assessed in relation to their possible implementation and efficacy in a South African context. Finally, the thesis concludes with an overall synopsis of the position in this country and some proposals for reform in the light of the international and constitutional commitments of the state.
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- Date Issued: 2000
Latent murderousness: an exploration of the nature and quality of object relations in rage-type murderers
- Authors: Cartwright, Duncan James
- Date: 2000
- Subjects: Murder Murder -- Case studies Murderers -- Psychology Criminal psychology Violence Narcissism Aggressiveness Anger
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2946 , http://hdl.handle.net/10962/d1002455
- Description: In this dissertation I investigate the intrapsychic make-up of rage-type offenders and explore the psychodynamics of the act of murder itself The dissertation begins with a discussion on the defining features of the act of rage-type murder. I then consider the role of personality characteristics and psychopathology in individuals who have committed such offences. With the basic features of the offender and act itself outlined, the following section reviews key areas of debate regarding the psychodynamics of violence and the intrapsychic make-up of the rage-type murderer. I first explore the nature of aggression as debated in psychoanalysis and conclude that the views expressed are often unn,ecessarily polarized regarding the origins of aggression and suggest that the specifics of particular types of aggression require consideration in order to assess their intrapsychic nature. The specifics of rage and violence are discussed with this in mind. In the second chapter of this section I develop a number of intrapsychic dimensions to be used in understanding how different types of violence are constituted. Psychodynamic contributions towards understanding rage-type murder, as a specific form of violence, are then discussed. Following this review, a number of directive ~uestions are formulated regarding (1) the intrapsychic dimension of rage-type murder; (2) the pJ;esence of the borderline personality in such offender~ and its intrapsychic nature; and (3) the_ specific psychodynamics that lie behind what is argued to be a defensive act of murder. A multiple case study approach, using nine imprisoned rage-type offenders, is used to further explore the above issues. Court summary reports, the Thematic Apperception Test and the Psychoanalytic Research Interview comprised the research material, with particular emphasis placed on the interview material. The interview is approached from a psychoanalytic perspective and I develop some theoretical, technical and analytical guidelines to try to broaden Jhe use of psychoanalysis in the research domain. Findings of the research reveal a specific kind of defensive organization that is characterized by a constellation of object relations that I term the 'narcissistic exoskeleton'. I suggest that these findings best fit the description of a particular kind of borderline personality organization typified by apparent 'normality'. Other prominent aspects of the dimensions of violence observed in these cases include: (1) a poor representational capacity; (2) an interactional style characterized by uncontainable projective exchanges between victim and offender; (3) a collusive primary object relationship combined with the absence of an internalized 'third object'; (4) a 'two-faced' superego structure; (5) the internalization of traumatic experience that has become associated with a bad object system; (6) phantasies of restoring ideal good in external objects alongside conscious fantasies of annihilation. Within the context of these factors the intrapsychic events that lead to the act itself are discussed. It is found that a collapse of the 'narcissistic exoskeleton', the intrusion of the bad object system and the unbearable shame that this evokes in the offender are prominent features of what culminates in an act of explosive rage and projective identification. Some of the implications of my research are briefly discussed in the concluding chapter.
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- Date Issued: 2000
Genetic variation within and between some rare and common taxa of Cape Proteaceae and the implications for their conservation
- Authors: Brown, Susan Ann
- Date: 2000
- Subjects: Proteaceae -- South Africa Nature conservation -- South Africa Plant conservation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3905 , http://hdl.handle.net/10962/d1003964
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- Date Issued: 2000
An investigation into dopamine-melatonin interactions in the rat Corpus striatum and pineal gland: a possible pineal-striatal axis
- Authors: Boyd, Clinton Shane
- Date: 2000
- Subjects: Pineal gland -- Research Melatonin Dopamine -- Physiological effect Dopamine Brain chemistry Rats -- Physiology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3906 , http://hdl.handle.net/10962/d1003965
- Description: Dysfunction of central dopaminergic systems has been implicated in neuroendocrine, neurodegenerative and psychiatric disorders. Monoamine oxidase and catechol-Omethyltransferase represent the key catabolic enzymes of dopamine, terminating neurotransmission following synaptic release of this catecholamine. Thus, both enzymes have been associated with the pathology of dopaminergic systems and represent therapeutic targets elf enormous clinical importance. Some neuroendocrine and circadian effects of melatonin have been attributed to an antidopamimetic effect of this pineal hormone in the hypothalamus and pituitary. Furthermore, both melatonin and dopamine modulate the behavioural output of the mesencephalic dopaminergic pathways of the basal ganglia, including movement disorders. However, the biochemical basis for the tonic inhibitory effect of melatonin in the nigro-striatal pathway has been poorly delineated. Thus, this study determined whether melatonin influences dopaminergic function in the corpus striatum of the Wistar rat by modulating monoamine oxidase and catecholO- methyltransferase activity. Reciprocally, the putative existence of an intrapineal dopaminergic system was investigated by determining the effect of selective dopaminergic agents, R-( -)apomorphine, haloperidol and dopamine, on indole metabolism of the pineal gland. The akinetic state of drug-induced catalepsy was employed as an animal model of Parkinson's disease to probe the neurotransmitter systems involved in the behavioural effects of melatonin. Indole metabolism was a reliable indicator of state-dependent metabolic fluxes in pineal gland function. These included a robust diurnal and seasonal variation in N-acetylserotonin and melatonin biosynthesis, and photoperiod- and drug-induced alterations of Inftabolism. The predominant changes could be attributed to an effect on serotonin N-acetyltransferase activity and/or the melatoninl5-methoxytryptophol ratio. Pineal 5-methoxyindole biosynthesis was determined primarily by the bioavailability of the corresponding 5-hydroxyindole and its affinity for hydroxyindole-O-methyltransferase. Evidence was found for the negative feedback or paracrine control of pineal indole metabolism by melatonin. A high inter-individual variability was observed in the biosynthesis of N-acetylserotonin and melatonin biosynthesis, and the weight of the pineal glands. Accordingly, the rats could be classified as either high or low capacity producers of these two indoles. R-(-)-apomorphine and dopamine in vitro, but not acute haloperidol in vivo, had dose- and phase-dependent effects on pineal indole metabolism. The predominant effect was a suppression of the scotophase-dependent induction ofN-acetylserotonin and melatonin biosynthesis by dopamine and R-( -)-apomorphine. It is postulated that these agonists inhibited nocturnal N-acetyltransferase activity via postsynaptic pineal D2 or D2-like receptors. The observed modulatory nature of the intrapineal dopaminergic system suggests that dopamine may be involved in the long-term regulation of pineal indole biosynthesis. Several lines of evidence are presented that the activity of striatal monoamine oxidase A and catechol-O-methyltransferase, represented predominantly by the soluble isoform, is statedependent and regulated in vivo by endogenous melatonin. Firstly, both enzymes showed a daynight variation in activity. Secondly, acute and subchronic administration and photoperiod manipulation studies indicated that both exogenous and endogenous melatonin inhibited each enzyme in a chronotypic fashion, with a more robust effect against catechol- -methyltransferase. The intensity of the in vivo effects was critically dependent on the dose, duration, route and the phase-timing of administration during the light dark cycle, and the length of the exposure to constant light. Melatonin in vitro had no effect on basal or Mg2+ -induced catechol-Omethyltransferase activity. Thus, it is proposed that the in vivo effects of the hormone can be attributed to a time-dependent change in the amount of active molecules of this enzyme. In contrast, melatonin and numerous other endogenous indolic compounds were found to be reversible inhibitors of striatal monoamine oxidase A in vitro. Structure-activity modeling revealed that the 5-methoxy moiety on the indole nucleus and substitution of the free primary amine of these compounds were the principal determinants of the potency and time-dependency of inhibition. Thus melatonin most likely has a direct inhibitory effect in vivo at the level of the active site of monoamine oxidase A. Exogenous melatonin alone had no cataleptogenic potential whereas a variety of behavioural responses were observed following intraperitoneal administration of y-hydroxybutyrate. The latter responses were state-dependent with day-night variations in intensity. Furthermore, yhydroxybutyrate stimulated melatonin biosynthesis during the photophase both in vitro and in vivo. These results point to a possible involvement of melatonin in the behavioural and neurochemical effects of y-hydroxybutyrate. Thus the general conclusion is that dopamine and melatonin display functional antagonism at the level of the pineal gland and corpus striatum of the Wistar rats. Therefore melatonin may be an important homeostatic modulator of dopaminergic neurotransmission throu~out the central nervous system. Furthermore, the putative existence of a functional pineal-striatal axis would greatly strengthen the argument for a holistic concept of brain homeostasis. The ability of endogenous melatonin to regulate monoamine oxidase A and catechol-O-methyltransferase may represent an alternative strategy for the treatment of disorders associated with these enzymes.
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- Date Issued: 2000
Studies of the population structure and generic diversity of domesticated and "wild" ostriches (Struthio camelus)
- Authors: Bezuidenhout, Cornelius Carlos
- Date: 2000
- Subjects: Ostriches Ostriches -- Genetics Ostriches -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3907 , http://hdl.handle.net/10962/d1003966
- Description: DNA sequencing and restriction fragment length polymorphism analysis (RFLP) of polymerase chain reaction (PCR) amplified mitochondrial DNA fragments, and random amplified polymorphic DNA sequence (RAPD) analysis were techniques evaluated in this study for applicability in the investigation various aspects of genetic diversity within the ostrich (Struthio camelus). The genetic aspects that were investigated were (i) relationships between ostrich subspecies, (ii) genetic variability between and within domesticated populations of southern African ostriches (Struthio camelus australis), (iii) linking egg production in domesticated ostriches to RAPD profiles, and (iv) determining the zygosity of twin ostriches. In the first part of this study DNA sequencing and the polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) methods were evaluated for resolving genetic differences in the small mtDNA fragments ofthe ostrich. DNA sequencing ofPCR amplified 450 bp 12S rRNA gene fragments of representatives from the southern African population ostrich (S.c. australis) did not reveal any differences between the populatiohs from different geographical areas, representing ostrich lineages with different breeding histories. The PCRRFLP analysis ofmtDNA fragments (450 bp 12S rRNA gene fragment and 550 bp D-loop region) also did not reveal any genetic variability between the domesticated s.,c. australis populations included in this study. PCR-RFLP analysis of a 450 bp 12S rRNA gene fragment, however, showed differences between the subspecies s.c. australis and s.c. molybdophanes. The proportion of shared fragments (F) between these two subspecies was 0.286 and nucleotide sequence divergence estimated at 8.9 %. Divergence time between these two subspecies was estimated at 4.5 million years ago. The data presented from this study are comparable to the data from a previous study in which the entire mitochondrial genome and a larger number of restriction enzymes were used. The PCR-RFLP method thus demonstrated its usefulness for genetic studies of ostriches at thesubspecies level. The sequences used in this study could not reveal any markers that were useful for genetic studies of ostriches at the population level. In the second part of the study the RAPD method was evaluated for application in the genetic studies of ostriches. RAPD profiles, based on three RAPD primers, revealed differences between three subspecies of ostriches and indicated relationships between these subspecies that are consistent with observations from other studies. The numerical analysis of pooled and individual primer data demonstrated that the subspecies s.c. australis is more closely related to s.c. massaicus than to s.c. molybdophanes. RAPD marker differences between s.c. molybdophanes on the one hand, and s.c. massaicus and s.c. australis on the other is also consistent with observations from studies that proposed separate specie~ status for s.c. molybdophanes. RAPD analysis by five primers revealed geographic variation between s.c. australis populations. The clustering patterns observed in the dendrograms and Neighbour Joining Trees generated by computer programs showed trends of separating ostric1;t populations into geographical groups, possibly reflecting their different breeding histories. In the RAPD profiles of the inbred population, band-sharing was generally greater than in the outbreeding group. RAPD analysis thus showed that it may be a useful method in the population studies of domesticated S. c. australis. RAPDs also generated data that grouped ostriches according to trends in egg production capabilities. Analysis ofRAPD profiles by computer software showed a Neighbour Joining Tree and a dendrogram that predominantly grouped ostriches into clusters associated with either good or poor egg production. Evidence supporting the suitability of RAPDs as a tool in breeding programmes of ostriches was thus provided by this study. RAPDs also provided data, demonstrating that two sets of ostrich twins were non-identical twins. It was demonstrated by this study that RAPDs analysis may be a useful technique for applying to (1) systematic (2) population (3) breeding and (4) twin studies of ostriches (Struthio camelus).
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- Date Issued: 2000