Etude postcoloniale : une analyse thematique et stylistique de quelques reuvres en litterature africaine francophone
- Authors: Mzite, Martha
- Date: 2017
- Language: French
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21356 , http://hdl.handle.net/10962/8116
- Description: This study is a thematic and a stylistic analysis of five novels written by five francophone novelists namely: Calixthe Beyala (La Plantation), Assia Djebar (Nulle part dans la maison de mon pere), Fatou Diome (Celles qui attendent ), Emmanuel Dongala (Photo de groupe au bord du fleuve) and Rabia Diallo (Amours cruelles, beaute coupable). The novels under study investigate the ways in which African women’s lives are affected by factors such as conflict and financial issues. Through the analysis of the above mentioned novels this research seeks to contribute to the body of knowledge in the following ways. Since a lot of literature already exists on African migrants in Europe moreover little information analyses the conditions of those who remain behind hence this thesis seeks to provide an analysis of the plight of mothers, wives and children who remain in the country of origin waiting for the departed men. To shed light on women emancipation, this research also analyses the evolution of women solidarity before and after independence. In relation to the theoretical framework, pro feminist and stylistics theories form the theoretical basis of this study. It is against this background that it can be deduced that the analysis of these set books shows that gender issues aggravate the suppression of African women. As a result, this lessens the circumstances that favor the attainment of selfrealisation. Simone de Beauvoir’s notion of ‘consciousness of oppression’, ‘one is not born a woman’ and Spivak’s essay entitled “Can the Subaltern Speak?” form the theoretical aspect of this research. Simone de Beauvoir’s concept “one is not born a woman”, unfolds the origin of all the factors that subjugate women in society. When she postulates the idea of “consciousness of oppression”, she calls on women to be mindful of their surroundings and free themselves from all societal values that infringe on their rights. The linguistic analysis in this research provides insight into the women’s speech and why they choose certain words. Over and above these concerns, it can be concluded that by emulating the example of these fictional female characters, African women can come together and contribute to their own iii empowerment. In regard to migration, the women and the children who remain behind suffer more than the migrants. , Cette etude est une analyse thematique et stylistique de cinq romans ecrits par cinq romanciers francophones, a savoir Calixthe Beyala (La Plantation), Assia Djebar (Nulle part dans la maison de mon pere), Fatou Diome (Celles qui attendent), Emmanuel Dongala (Photo de groupe au bord du fleuve) et Rabia Diallo (Amours cruelles, beaute coupable). Les romans a l'etude etudient les faqons dont la vie des femmes africaines est affectee par des facteurs tels que les conflits et les questions financieres. En analysant ces romans cette recherche vise a contribuer dans la banque des donnees a travers les manieres suivantes. Etant donne qu'il existe deja beaucoup d’informations sur les migrants africains en Europe, peu d'informations analysent les conditions de ceux qui restent dans le pays d’origine. A cet egard, cette these vise a fournir une analyse du sort des meres, des epouses et des enfants qui restent dans le pays d'origine en attendant les hommes qui sont partis. Pour mettre en lumiere Emancipation des femmes, cette recherche analyse egalement Evolution de la solidarite de femmes avant et apres l'independance. En ce qui concerne le cadre theorique, les theories pro-feministes et stylistiques forment la base theorique de cette etude. L'analyse de ces ouvrages montre que les questions de genre accentuent l’oppression des femmes africaines. En consequence, cela diminue les circonstances qui favorisent la realisation de soi. La notion de « conscience de l'oppression » de Simone de Beauvoir, et aussi sa pensee selon laquelle « on ne nait pas femme, on le devient » forment la base theorique de cette these. Cette vision etablit l’origine de tous les facteurs qui asservissent les femmes dans la societe. La conscience de l’oppression invite la femme a prendre connaissance de son environnement et de se liberer de toutes les valeurs de la societe qui porte atteinte a ses droits. La problematique se resume ainsi « les subalternes, peuvent-elles parler ? » L'analyse linguistique de cette recherche donne un aperqu de la parole des femmes et pourquoi elles choisissent certains mots. Au-dela de ces preoccupations, on peut conclure que, en imitant l'exemple de ces personnages feminins fictifs, les femmes africaines peuvent s’unir et contribuer a leur v propre emancipation. En ce qui concerne la migration, il sera demontre comment les femmes et les enfants qui restent derriere souffrent aussi bien que les migrants.
- Full Text:
- Date Issued: 2017
- Authors: Mzite, Martha
- Date: 2017
- Language: French
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21356 , http://hdl.handle.net/10962/8116
- Description: This study is a thematic and a stylistic analysis of five novels written by five francophone novelists namely: Calixthe Beyala (La Plantation), Assia Djebar (Nulle part dans la maison de mon pere), Fatou Diome (Celles qui attendent ), Emmanuel Dongala (Photo de groupe au bord du fleuve) and Rabia Diallo (Amours cruelles, beaute coupable). The novels under study investigate the ways in which African women’s lives are affected by factors such as conflict and financial issues. Through the analysis of the above mentioned novels this research seeks to contribute to the body of knowledge in the following ways. Since a lot of literature already exists on African migrants in Europe moreover little information analyses the conditions of those who remain behind hence this thesis seeks to provide an analysis of the plight of mothers, wives and children who remain in the country of origin waiting for the departed men. To shed light on women emancipation, this research also analyses the evolution of women solidarity before and after independence. In relation to the theoretical framework, pro feminist and stylistics theories form the theoretical basis of this study. It is against this background that it can be deduced that the analysis of these set books shows that gender issues aggravate the suppression of African women. As a result, this lessens the circumstances that favor the attainment of selfrealisation. Simone de Beauvoir’s notion of ‘consciousness of oppression’, ‘one is not born a woman’ and Spivak’s essay entitled “Can the Subaltern Speak?” form the theoretical aspect of this research. Simone de Beauvoir’s concept “one is not born a woman”, unfolds the origin of all the factors that subjugate women in society. When she postulates the idea of “consciousness of oppression”, she calls on women to be mindful of their surroundings and free themselves from all societal values that infringe on their rights. The linguistic analysis in this research provides insight into the women’s speech and why they choose certain words. Over and above these concerns, it can be concluded that by emulating the example of these fictional female characters, African women can come together and contribute to their own iii empowerment. In regard to migration, the women and the children who remain behind suffer more than the migrants. , Cette etude est une analyse thematique et stylistique de cinq romans ecrits par cinq romanciers francophones, a savoir Calixthe Beyala (La Plantation), Assia Djebar (Nulle part dans la maison de mon pere), Fatou Diome (Celles qui attendent), Emmanuel Dongala (Photo de groupe au bord du fleuve) et Rabia Diallo (Amours cruelles, beaute coupable). Les romans a l'etude etudient les faqons dont la vie des femmes africaines est affectee par des facteurs tels que les conflits et les questions financieres. En analysant ces romans cette recherche vise a contribuer dans la banque des donnees a travers les manieres suivantes. Etant donne qu'il existe deja beaucoup d’informations sur les migrants africains en Europe, peu d'informations analysent les conditions de ceux qui restent dans le pays d’origine. A cet egard, cette these vise a fournir une analyse du sort des meres, des epouses et des enfants qui restent dans le pays d'origine en attendant les hommes qui sont partis. Pour mettre en lumiere Emancipation des femmes, cette recherche analyse egalement Evolution de la solidarite de femmes avant et apres l'independance. En ce qui concerne le cadre theorique, les theories pro-feministes et stylistiques forment la base theorique de cette etude. L'analyse de ces ouvrages montre que les questions de genre accentuent l’oppression des femmes africaines. En consequence, cela diminue les circonstances qui favorisent la realisation de soi. La notion de « conscience de l'oppression » de Simone de Beauvoir, et aussi sa pensee selon laquelle « on ne nait pas femme, on le devient » forment la base theorique de cette these. Cette vision etablit l’origine de tous les facteurs qui asservissent les femmes dans la societe. La conscience de l’oppression invite la femme a prendre connaissance de son environnement et de se liberer de toutes les valeurs de la societe qui porte atteinte a ses droits. La problematique se resume ainsi « les subalternes, peuvent-elles parler ? » L'analyse linguistique de cette recherche donne un aperqu de la parole des femmes et pourquoi elles choisissent certains mots. Au-dela de ces preoccupations, on peut conclure que, en imitant l'exemple de ces personnages feminins fictifs, les femmes africaines peuvent s’unir et contribuer a leur v propre emancipation. En ce qui concerne la migration, il sera demontre comment les femmes et les enfants qui restent derriere souffrent aussi bien que les migrants.
- Full Text:
- Date Issued: 2017
Creating evidence-based guidelines for healthy eating educational campaigns aimed at low-income South Africans: a case study of Grahamstown
- Authors: Booth, Christopher
- Date: 2016
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/3336 , vital:20485
- Description: Through a literature review and qualitative research, this study explores what a media-centric nutritional intervention needs to include in order to be effective amongst those whose health is most impacted by poor nutrition – poorer and mostly black South Africans. The study sketches the current nutritional landscape of South Africa, and draws on both Behaviour Change Communication and Media Effect theories to hypothesise how a campaign might be devised to change popular understandings of the relationship between health and nutrition, and inspire some change in food consumption behaviours and choices. The study explores the key factors that drive nutritional behaviours (including the environmental constraint of cost, the peer pressure and socialisation of food, and the desire for knowledge and change) and explores how media-based interventions could be more effective. To do this, this study creates three layers of an idealised and hypothetical “Super 7” fruit and vegetable consumption promotion campaign. From this data, and the insights developed, new guidelines for possible future nutritional education campaigns are suggested and developed.
- Full Text:
- Date Issued: 2016
- Authors: Booth, Christopher
- Date: 2016
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/3336 , vital:20485
- Description: Through a literature review and qualitative research, this study explores what a media-centric nutritional intervention needs to include in order to be effective amongst those whose health is most impacted by poor nutrition – poorer and mostly black South Africans. The study sketches the current nutritional landscape of South Africa, and draws on both Behaviour Change Communication and Media Effect theories to hypothesise how a campaign might be devised to change popular understandings of the relationship between health and nutrition, and inspire some change in food consumption behaviours and choices. The study explores the key factors that drive nutritional behaviours (including the environmental constraint of cost, the peer pressure and socialisation of food, and the desire for knowledge and change) and explores how media-based interventions could be more effective. To do this, this study creates three layers of an idealised and hypothetical “Super 7” fruit and vegetable consumption promotion campaign. From this data, and the insights developed, new guidelines for possible future nutritional education campaigns are suggested and developed.
- Full Text:
- Date Issued: 2016
Synthesis and characterization of group 12 dithiolate complexes as single source precursors for the preparation of hexadecylamine capped metal sulfide nanoparticles and polymer
- Authors: Osuntokun, Jejenija
- Date: 2016
- Subjects: Nanotechnology Nanoparticles Semiconductors
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/14060 , vital:39801
- Description: A series of heteroleptic mixed ligand complexes of some alkyl substituted thiourea, tetramethyl thiuram disulfide and 1-cyano-1-carboethoxy-2,2 ditholate of Zn(II) Cd(II) and Hg(II) have been synthesized by stoichiometry reactions of the ligands with respective metal salts. They have been characterized with analytical and spectroscopic techniques. Seven out of the 19 complexes synthesized are pyridine 2, 2 bipyridine and 1, 10 phenanthroline adducts of dissopropyl parent adducts of Zn(II) and Cd(II) complexes. All the complexes are proposed as four coordinate except the pyridine adducts, 2, 2’ bipyridine and 1, 10 phenanhroline adducts that are proposed as five and six coordinate respectively. All the complexes are solid, air stable and moisture stable for a many months. They are not soluble in common organic solvents but partially soluble in coordinating solvents like DMF and DMSO and due to their insolubility problems all attempts to grow single crystal of the complexes proved abortive. The complexes gave respective metal sulfide on thermal decomposition in TGA and this makes them to be potentially useful single source precursor for the synthesis of metal sulfide. All the complexes were invariably thermolysed in HDA to synthesis a series of HDA-capped ZnS, CdS and HgS nanoparticles. The optical properties of the nanoparticles reveal that they are all blue-shifted from the absorbance edge and this confirms quantum confinement of the nanoparticles. The transmittance electron microscope showed that the nanoparticles are in nanodimension. ZnS nanoparticles from the pyridine adducts gave HDA-capped ZnS nanoparticles with a mixture of hexagonal and cubic phases while the HDA capped CdS from the 2, 2 bipyridine and 1,10 phenanthroline gave anisotropic nanoparticles. The sizes of the CdS from the 1,10 phenanthroline adducts were also found to be biggest while CdS nanoparticles from 2,2 bipyridine adduct were also revealed to be bigger than the particle sizes obtained from the parent complex, (1-cyano-1 carboethoxyethylene-2,2-dithiolato- κ,S’S)-bis(N, N’-diisopropylthiourea -κS)cadmium(II). ZnS and CdS polymer encapsulated nanocomposites were also synthesized using a solution casting method. The polymers employed were; Polymethyl metharcrylate (PMMA), Poly(vinly alcohol) (PVA), and poly vinyl pyrrolidone (PVP). The structural and thermal properties of the pure polymers and the respective nanocomposites were investigated. It was observed that the ZnS/PVA and CdS/PVA were the most thermally stable composites when the thermal stability of the pure polymers were compared relative to the nanocomposites using data obtained from thermal decomposition results of the TGA.
- Full Text:
- Date Issued: 2016
- Authors: Osuntokun, Jejenija
- Date: 2016
- Subjects: Nanotechnology Nanoparticles Semiconductors
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/14060 , vital:39801
- Description: A series of heteroleptic mixed ligand complexes of some alkyl substituted thiourea, tetramethyl thiuram disulfide and 1-cyano-1-carboethoxy-2,2 ditholate of Zn(II) Cd(II) and Hg(II) have been synthesized by stoichiometry reactions of the ligands with respective metal salts. They have been characterized with analytical and spectroscopic techniques. Seven out of the 19 complexes synthesized are pyridine 2, 2 bipyridine and 1, 10 phenanthroline adducts of dissopropyl parent adducts of Zn(II) and Cd(II) complexes. All the complexes are proposed as four coordinate except the pyridine adducts, 2, 2’ bipyridine and 1, 10 phenanhroline adducts that are proposed as five and six coordinate respectively. All the complexes are solid, air stable and moisture stable for a many months. They are not soluble in common organic solvents but partially soluble in coordinating solvents like DMF and DMSO and due to their insolubility problems all attempts to grow single crystal of the complexes proved abortive. The complexes gave respective metal sulfide on thermal decomposition in TGA and this makes them to be potentially useful single source precursor for the synthesis of metal sulfide. All the complexes were invariably thermolysed in HDA to synthesis a series of HDA-capped ZnS, CdS and HgS nanoparticles. The optical properties of the nanoparticles reveal that they are all blue-shifted from the absorbance edge and this confirms quantum confinement of the nanoparticles. The transmittance electron microscope showed that the nanoparticles are in nanodimension. ZnS nanoparticles from the pyridine adducts gave HDA-capped ZnS nanoparticles with a mixture of hexagonal and cubic phases while the HDA capped CdS from the 2, 2 bipyridine and 1,10 phenanthroline gave anisotropic nanoparticles. The sizes of the CdS from the 1,10 phenanthroline adducts were also found to be biggest while CdS nanoparticles from 2,2 bipyridine adduct were also revealed to be bigger than the particle sizes obtained from the parent complex, (1-cyano-1 carboethoxyethylene-2,2-dithiolato- κ,S’S)-bis(N, N’-diisopropylthiourea -κS)cadmium(II). ZnS and CdS polymer encapsulated nanocomposites were also synthesized using a solution casting method. The polymers employed were; Polymethyl metharcrylate (PMMA), Poly(vinly alcohol) (PVA), and poly vinyl pyrrolidone (PVP). The structural and thermal properties of the pure polymers and the respective nanocomposites were investigated. It was observed that the ZnS/PVA and CdS/PVA were the most thermally stable composites when the thermal stability of the pure polymers were compared relative to the nanocomposites using data obtained from thermal decomposition results of the TGA.
- Full Text:
- Date Issued: 2016
Characterization of the co-chaperones of Hsp70 and Hsp90 in Trypanosoma brucei and their potential partnerships
- Authors: Mokoena, Fortunate
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54543 , vital:26583
- Description: African Trypanosomiasis, which is caused by Trypanosoma brucei, is one of the crippling agents of social and economic development in Africa. T. brucei cycles between the cold-blooded insect vector, the tsetse fly (Glossina spp), and warm-blooded mammalian hosts. T. brucei, T. cruzi and L. major are mammal infecting kinetoplastid parasites that are collectively referred to as TriTryps. These parasites experience extreme environments as they move between their warm-blooded mammalian hosts and cold-blooded insect vectors which trigger extensive morphological transformations during the life-cycle of the parasite. Molecular chaperones have been implicated in parasite differentiation. TriTryps display significant expansions and diversity in the gene complements encoding molecular chaperones, especially J-proteins. Generally, J-proteins function as co-chaperones of Hsp70s, forming part of vital protein homeostasis processes. Hsp70s show a high degree of conservation, while J-proteins appear to be an extreme case of taxonomic radiation. Although several studies have focused on the molecular and cell biology of Hsp70s in some kinetoplastid parasites, knowledge is still lacking pertaining to J-proteins and their partnerships with Hsp70s. This thesis focused on the classification of kinetoplastid Jproteins into the four types by examining the domain organizations using T. brucei as a guide. The potential partnership of J-proteins and Hsp70s were postulated based on predicted subcellular localization. Kinetoplastid parasites, particularly T. brucei, have evolved an expanded and specialized J-protein machinery, likely to be a consequence of an evolutionary fitness/trait to adapt to diverse environment present in hosts and vectors. These analyses will yield insight into the process of parasite differentiation as well as provide new leads for chemotherapeutic treatments. The presence of the STI1 mediated Hsp90 hetero-complex formation has not been confirmed in T. brucei. To this end, in silico and biochemical techniques were used to characterize the role of TbSTI1, as an adaptor protein of Hsp70 and Hsp90. Through domain architecture analysis, sequence alignments, phylogenetic analysis and three-dimensional structure prediction, TbSTI1 was demonstrated to be the most conserved TPR containing co-chaperone of Hsp70 and Hsp83 in T. brucei and also shown to be highly similar to its eukaryotic homologues. Recombinant TbSTI1 was overproduced and purified in E.coli cells and subsequently shown to associate with TcHsp70 in a concentration dependent manner and associate weakly with TbHsp70.4. TbSTI1 and TbHsp83 were also demonstrated to be expressed and upregulated upon exposure to heat shock at the bloodstream stage of parasite development. In conclusion, this study is the first to report the interaction of TbSTI1 with a chaperone. Interactions between TbSTI1 and Hsp70s were demonstrated and therefore, the formation of the hetero-complex is predicted based the similarity of TbSTI1 to other STI1 proteins.
- Full Text:
- Date Issued: 2015
- Authors: Mokoena, Fortunate
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54543 , vital:26583
- Description: African Trypanosomiasis, which is caused by Trypanosoma brucei, is one of the crippling agents of social and economic development in Africa. T. brucei cycles between the cold-blooded insect vector, the tsetse fly (Glossina spp), and warm-blooded mammalian hosts. T. brucei, T. cruzi and L. major are mammal infecting kinetoplastid parasites that are collectively referred to as TriTryps. These parasites experience extreme environments as they move between their warm-blooded mammalian hosts and cold-blooded insect vectors which trigger extensive morphological transformations during the life-cycle of the parasite. Molecular chaperones have been implicated in parasite differentiation. TriTryps display significant expansions and diversity in the gene complements encoding molecular chaperones, especially J-proteins. Generally, J-proteins function as co-chaperones of Hsp70s, forming part of vital protein homeostasis processes. Hsp70s show a high degree of conservation, while J-proteins appear to be an extreme case of taxonomic radiation. Although several studies have focused on the molecular and cell biology of Hsp70s in some kinetoplastid parasites, knowledge is still lacking pertaining to J-proteins and their partnerships with Hsp70s. This thesis focused on the classification of kinetoplastid Jproteins into the four types by examining the domain organizations using T. brucei as a guide. The potential partnership of J-proteins and Hsp70s were postulated based on predicted subcellular localization. Kinetoplastid parasites, particularly T. brucei, have evolved an expanded and specialized J-protein machinery, likely to be a consequence of an evolutionary fitness/trait to adapt to diverse environment present in hosts and vectors. These analyses will yield insight into the process of parasite differentiation as well as provide new leads for chemotherapeutic treatments. The presence of the STI1 mediated Hsp90 hetero-complex formation has not been confirmed in T. brucei. To this end, in silico and biochemical techniques were used to characterize the role of TbSTI1, as an adaptor protein of Hsp70 and Hsp90. Through domain architecture analysis, sequence alignments, phylogenetic analysis and three-dimensional structure prediction, TbSTI1 was demonstrated to be the most conserved TPR containing co-chaperone of Hsp70 and Hsp83 in T. brucei and also shown to be highly similar to its eukaryotic homologues. Recombinant TbSTI1 was overproduced and purified in E.coli cells and subsequently shown to associate with TcHsp70 in a concentration dependent manner and associate weakly with TbHsp70.4. TbSTI1 and TbHsp83 were also demonstrated to be expressed and upregulated upon exposure to heat shock at the bloodstream stage of parasite development. In conclusion, this study is the first to report the interaction of TbSTI1 with a chaperone. Interactions between TbSTI1 and Hsp70s were demonstrated and therefore, the formation of the hetero-complex is predicted based the similarity of TbSTI1 to other STI1 proteins.
- Full Text:
- Date Issued: 2015
Nutritional value and cultivation requirements of Cleome Gynandra: a wild vegetable growing in the Eastern Cape Province, South Africa
- Sowunmi, Linda Ifeanyichukwu
- Authors: Sowunmi, Linda Ifeanyichukwu
- Date: 2015
- Subjects: Ethnobotany -- South Africa -- Eastern Cape Vegetables -- South Africa -- Eastern Cape Nutrition -- South Africa -- Evaluation
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2600 , vital:27907
- Description: South Africa has wide ranges of plants among which are leafy vegetables growing in the wild. These wild vegetables have been reported to have high nutritive and medicinal potentials. Yet, there is still high prevalence of malnutrition and micronutrients deficiencies among the low income bracket of the population. Effective utilization of wild vegetables has been proposed as part of the solutions to address the problem of dietary deficiencies among the populace. Their importance is mainly as relish to accompany and complement starch based diets. They are also known to serve as supplements for food which have the potential to improve the health status of its consumers in many rural communities. Cleome gynandra L. (Capparaceae) is one of the underutilized species mentioned during asurvey conducted in Nkonkobe municipality of the Eastern Cape Province, South Africa. The plant is an erect annual herb with alternate, palmately compound leaves and its petals are white, pink or lilac. It grows as a weed in this part of the Province and is usually gathered from the wild for food and medicine. It is commonly found on wastes land, road sides and on grass lands. Therefore, this research work was designed to contribute to the possible domestication of this wild vegetable in order to explore the nutritive and therapeutic potentials which would broaden the food base in the Eastern Cape Province. The ultra-micromorphological features of plants have become an essential tool in proper identification and authentication of several plant species. In the light of this, the micromorphology of Cleome gynandra was examined to reveal the micro-morphological characters of the plantand to determine if micro and macro mineral elements are present using energy dispersive x-rays. The present study revealed the epidermal cells of the leaves to be asymmetric in shape with undulating cell walls having four subsidiary cells around the stomata. The leaves have anomocyctic stomata which are more distributed in the abaxial surface than the adaxial surface. The mean length and width of the guard cells in the abaxial surface are 0.09 ± 0.01 mm and 0.08 ± 0.01 mm respectively while that of adaxial surface are 0.1± 0.01 mm and 0.07 ± 0.01 mm respectively. The energy dispersive x-rays (EDXS) micro-analysis of the leaf revealed the presence of phosphorus, manganese, iron, calcium, sodium, magnesium, potassium and zinc as the major constituents of the crystal deposits present in the stomata pores and the mesophyll. C. gynandra was collected from the wild and analysed for its mineral and proximatecomposition using standard analytical methods. The plant showed high levels of sodium, iron, zinc, calcium and potassium while many other macro and micro minerals were moderately present. Amongst the proximate factors investigated, moisture content was found to be 82.1% while crude fibre and protein contents were 39.9 percent and 31.03 percent respectively. Vitamin C was also high (345.3 mg/100g). The anti-nutrients compositions revealed low concentrations of oxalate (7.4 ± 0.4) and phytate (0.6 ± 0.0) mg/100g. The study revealed high nutritive value of the species growing naturally from the wild. Interest in the phenolic compounds has greatly increased recently because these compounds have been implicated in suppressing the risk of degenerative diseases in humans. The pharmacological properties of plants may be related to their antioxidant capacities and hence there was need to investigate the antioxidant potential using aqueous, ethanolic and acetone extracts of different parts of C. gynandra. The quantities of phenols, flavonoids and flavonols were significantly higher (p < 0.05) in both aqueous and ethanol extracts of the leaf while the concentration of proanthocyanidins was higher in the aqueous stem extract compared to other plant parts. The aqueous extract of the different parts exhibited better ABTS, reducing power and NO radical scavenging abilities than ethanol extract.
- Full Text:
- Date Issued: 2015
- Authors: Sowunmi, Linda Ifeanyichukwu
- Date: 2015
- Subjects: Ethnobotany -- South Africa -- Eastern Cape Vegetables -- South Africa -- Eastern Cape Nutrition -- South Africa -- Evaluation
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2600 , vital:27907
- Description: South Africa has wide ranges of plants among which are leafy vegetables growing in the wild. These wild vegetables have been reported to have high nutritive and medicinal potentials. Yet, there is still high prevalence of malnutrition and micronutrients deficiencies among the low income bracket of the population. Effective utilization of wild vegetables has been proposed as part of the solutions to address the problem of dietary deficiencies among the populace. Their importance is mainly as relish to accompany and complement starch based diets. They are also known to serve as supplements for food which have the potential to improve the health status of its consumers in many rural communities. Cleome gynandra L. (Capparaceae) is one of the underutilized species mentioned during asurvey conducted in Nkonkobe municipality of the Eastern Cape Province, South Africa. The plant is an erect annual herb with alternate, palmately compound leaves and its petals are white, pink or lilac. It grows as a weed in this part of the Province and is usually gathered from the wild for food and medicine. It is commonly found on wastes land, road sides and on grass lands. Therefore, this research work was designed to contribute to the possible domestication of this wild vegetable in order to explore the nutritive and therapeutic potentials which would broaden the food base in the Eastern Cape Province. The ultra-micromorphological features of plants have become an essential tool in proper identification and authentication of several plant species. In the light of this, the micromorphology of Cleome gynandra was examined to reveal the micro-morphological characters of the plantand to determine if micro and macro mineral elements are present using energy dispersive x-rays. The present study revealed the epidermal cells of the leaves to be asymmetric in shape with undulating cell walls having four subsidiary cells around the stomata. The leaves have anomocyctic stomata which are more distributed in the abaxial surface than the adaxial surface. The mean length and width of the guard cells in the abaxial surface are 0.09 ± 0.01 mm and 0.08 ± 0.01 mm respectively while that of adaxial surface are 0.1± 0.01 mm and 0.07 ± 0.01 mm respectively. The energy dispersive x-rays (EDXS) micro-analysis of the leaf revealed the presence of phosphorus, manganese, iron, calcium, sodium, magnesium, potassium and zinc as the major constituents of the crystal deposits present in the stomata pores and the mesophyll. C. gynandra was collected from the wild and analysed for its mineral and proximatecomposition using standard analytical methods. The plant showed high levels of sodium, iron, zinc, calcium and potassium while many other macro and micro minerals were moderately present. Amongst the proximate factors investigated, moisture content was found to be 82.1% while crude fibre and protein contents were 39.9 percent and 31.03 percent respectively. Vitamin C was also high (345.3 mg/100g). The anti-nutrients compositions revealed low concentrations of oxalate (7.4 ± 0.4) and phytate (0.6 ± 0.0) mg/100g. The study revealed high nutritive value of the species growing naturally from the wild. Interest in the phenolic compounds has greatly increased recently because these compounds have been implicated in suppressing the risk of degenerative diseases in humans. The pharmacological properties of plants may be related to their antioxidant capacities and hence there was need to investigate the antioxidant potential using aqueous, ethanolic and acetone extracts of different parts of C. gynandra. The quantities of phenols, flavonoids and flavonols were significantly higher (p < 0.05) in both aqueous and ethanol extracts of the leaf while the concentration of proanthocyanidins was higher in the aqueous stem extract compared to other plant parts. The aqueous extract of the different parts exhibited better ABTS, reducing power and NO radical scavenging abilities than ethanol extract.
- Full Text:
- Date Issued: 2015
Development and assessment of sustained release stavudine loaded microparticles
- Authors: Zindove, Chiedza Cathrine
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10962/54722 , vital:26603
- Description:
Stavudine (D4T) has been used as first line treatment for HIV/AIDS and is part of highly active anti retroviral treatment (HAART). It is an affordable medicine and its use is beneficial in resource limited settings. However D4T exhibits dose dependent side effects that may lead to non-adherence in patients. This study was undertaken to formulate, develop and manufacture a dosage form that could reduce dose dependent side effects by decreasing the dose of D4T but still exhibit antiretroviral (ARV) activity. The use of sustained release (SR) formulations of D4T that ensure constant levels of the D4T in the body would not only optimize therapy but also reduce the incidence of side effects thereby increasing patient adherence. SR microparticles containing 30mg D4T were manufactured and loaded into size 3 hard gelatine capsules prior to analysis. The D4T microparticles were manufactured by microencapsulation using non-aqueous oil-in-oil solvent evaporation approach. D4T-excipient, excipient-excipient interactions and D4T purity were assessed using Infrared Spectroscopy (IR), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Copolymers synthesized from acrylic and methacrylic acid esters viz., Eudragit® RSPO and S100 were used as rate retardant materials and the effect of microcrystalline cellulose (Avicel® PH102) on the microparticles was also investigated. Magnesium stearate was used as a droplet stabilizer and n-hexane was added to harden the microspheres formed in a liquid paraffin continuous phase. The microparticles were optimized using a Box Behnken design and Response Surface Methodology (RSM). The microparticles were characterized in terms of their flow properties and encapsulation efficiency (% EE), in addition to visualization of the surface morphology with Scanning Electron Microscopy. In vitro D4T release studies were performed using USP Apparatus III in media of different pH and the samples were analysed using a validated High Performance Liquid Chromatographic (HPLC) method with ultraviolet (UV) detection that had been developed and optimized using a Central Composite Design (CCD). The method was validated according to ICH guidelines. The IR spectra and DSC thermographs revealed that D4T exhibited thermal stability and there was no evidence of D4T-excipient and excipient-excipient interactions. The microparticles that were produced were white, free flowing and were obtained in a high yield with high encapsulation efficiency. Scanning Electron Microscopy studies revealed that the microparticles were spherical and porous in nature. In vitro D4T release extended to 12 hours and the mechanism of release was established using model dependent methods by fitting the data to a Zero order, First order, Higuchi and Hixson Crowell model. It was observed that the mechanism of D4T release was diffusion-controlled and that the data was best fitted to the Higuchi model with correlation coefficients > 0.9. The release mechanism was confirmed using the Korsmeyer-Peppas model that revealed that most of the formulations exhibited anomalous transport kinetics with the release exponent, n, ranging from 0.5
- Full Text:
- Date Issued: 2014
- Authors: Zindove, Chiedza Cathrine
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10962/54722 , vital:26603
- Description:
Stavudine (D4T) has been used as first line treatment for HIV/AIDS and is part of highly active anti retroviral treatment (HAART). It is an affordable medicine and its use is beneficial in resource limited settings. However D4T exhibits dose dependent side effects that may lead to non-adherence in patients. This study was undertaken to formulate, develop and manufacture a dosage form that could reduce dose dependent side effects by decreasing the dose of D4T but still exhibit antiretroviral (ARV) activity. The use of sustained release (SR) formulations of D4T that ensure constant levels of the D4T in the body would not only optimize therapy but also reduce the incidence of side effects thereby increasing patient adherence. SR microparticles containing 30mg D4T were manufactured and loaded into size 3 hard gelatine capsules prior to analysis. The D4T microparticles were manufactured by microencapsulation using non-aqueous oil-in-oil solvent evaporation approach. D4T-excipient, excipient-excipient interactions and D4T purity were assessed using Infrared Spectroscopy (IR), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Copolymers synthesized from acrylic and methacrylic acid esters viz., Eudragit® RSPO and S100 were used as rate retardant materials and the effect of microcrystalline cellulose (Avicel® PH102) on the microparticles was also investigated. Magnesium stearate was used as a droplet stabilizer and n-hexane was added to harden the microspheres formed in a liquid paraffin continuous phase. The microparticles were optimized using a Box Behnken design and Response Surface Methodology (RSM). The microparticles were characterized in terms of their flow properties and encapsulation efficiency (% EE), in addition to visualization of the surface morphology with Scanning Electron Microscopy. In vitro D4T release studies were performed using USP Apparatus III in media of different pH and the samples were analysed using a validated High Performance Liquid Chromatographic (HPLC) method with ultraviolet (UV) detection that had been developed and optimized using a Central Composite Design (CCD). The method was validated according to ICH guidelines. The IR spectra and DSC thermographs revealed that D4T exhibited thermal stability and there was no evidence of D4T-excipient and excipient-excipient interactions. The microparticles that were produced were white, free flowing and were obtained in a high yield with high encapsulation efficiency. Scanning Electron Microscopy studies revealed that the microparticles were spherical and porous in nature. In vitro D4T release extended to 12 hours and the mechanism of release was established using model dependent methods by fitting the data to a Zero order, First order, Higuchi and Hixson Crowell model. It was observed that the mechanism of D4T release was diffusion-controlled and that the data was best fitted to the Higuchi model with correlation coefficients > 0.9. The release mechanism was confirmed using the Korsmeyer-Peppas model that revealed that most of the formulations exhibited anomalous transport kinetics with the release exponent, n, ranging from 0.5
- Full Text:
- Date Issued: 2014
Implementation of Public Participation Policy approach in Mbombela Local Municipality of Mpumalanga Province of South Africa: an evaluation
- Authors: Ndlovu, Derick
- Date: 2013
- Language: English
- Type: Thesis , Doctoral , PhD (in Public Administration)
- Identifier: vital:11690 , http://hdl.handle.net/10353/d1013597
- Description: Since the dawn of democracy in 1994, South Africa has promulgated a number of progressive legislation and programmes in an effort to improve the well-being of its citizens. There is legislation and prescripts designed to provide policy and legal basis for a concerted and coherent pursuit of public participation in South Africa. There are various pieces of legislation that provide overarching principles and norms to guide the concerted enhancement of public participation in the local sphere of government. In spite of the plethora of policies and programmes, communities in various places continue to engage in service delivery protests. This study critically analyzed the implementation of public participation policy as a legislative core value for local government, with specific reference to Mbombela local municipality. In doing so, it critically explored the extent to which Mbombela local municipality involves the local communities in matters of local government such as in strategic decision making, the development of the IDP, performance management and in service delivery processes. The study employed a qualitative research methodology, relying mainly on secondary written sources of data, which reported on public participation and public administration. These sources include books, journals, internet sources, government legislation and policies. Data was also collected from Mbombela local municipality through interviews with municipal officials, members of ward committees, community development workers and the public. This study has found that Mbombela local municipality (MLM) relies primarily on ward committees, ward- based meetings and the Speakers outreach as mechanisms to facilitate public participation. The municipality seems to regard public participation as a crucial aspect in that a public participation unit was established; however the municipality is using a low level of participation, with limited power by citizens to influence strategic decisions. This means that communities and community organizations are involved on matters of the municipality only through attending community meetings therefore such meetings are not sufficient for effective public participation as communities should also be involved in more strategic and influential means such as participating in steering committees, development and economic forums. This study further found that some of the ward committees are not effectively functional as a result of lack of commitment from ward committee members, unavailability of some ard committee members due to their permanent job commitments and due to the difficulty that is caused by the vastness of some of the wards. This study also revealed hat there is no feedback provided to ward committees by the municipality on the ward committee reports that are submitted to the municipality on monthly bases, as a results some ward committee members are demotivated. This research study concludes that Mbombela local municipality is not effectively implementing local government legislation in respect to public participation.
- Full Text:
- Date Issued: 2013
- Authors: Ndlovu, Derick
- Date: 2013
- Language: English
- Type: Thesis , Doctoral , PhD (in Public Administration)
- Identifier: vital:11690 , http://hdl.handle.net/10353/d1013597
- Description: Since the dawn of democracy in 1994, South Africa has promulgated a number of progressive legislation and programmes in an effort to improve the well-being of its citizens. There is legislation and prescripts designed to provide policy and legal basis for a concerted and coherent pursuit of public participation in South Africa. There are various pieces of legislation that provide overarching principles and norms to guide the concerted enhancement of public participation in the local sphere of government. In spite of the plethora of policies and programmes, communities in various places continue to engage in service delivery protests. This study critically analyzed the implementation of public participation policy as a legislative core value for local government, with specific reference to Mbombela local municipality. In doing so, it critically explored the extent to which Mbombela local municipality involves the local communities in matters of local government such as in strategic decision making, the development of the IDP, performance management and in service delivery processes. The study employed a qualitative research methodology, relying mainly on secondary written sources of data, which reported on public participation and public administration. These sources include books, journals, internet sources, government legislation and policies. Data was also collected from Mbombela local municipality through interviews with municipal officials, members of ward committees, community development workers and the public. This study has found that Mbombela local municipality (MLM) relies primarily on ward committees, ward- based meetings and the Speakers outreach as mechanisms to facilitate public participation. The municipality seems to regard public participation as a crucial aspect in that a public participation unit was established; however the municipality is using a low level of participation, with limited power by citizens to influence strategic decisions. This means that communities and community organizations are involved on matters of the municipality only through attending community meetings therefore such meetings are not sufficient for effective public participation as communities should also be involved in more strategic and influential means such as participating in steering committees, development and economic forums. This study further found that some of the ward committees are not effectively functional as a result of lack of commitment from ward committee members, unavailability of some ard committee members due to their permanent job commitments and due to the difficulty that is caused by the vastness of some of the wards. This study also revealed hat there is no feedback provided to ward committees by the municipality on the ward committee reports that are submitted to the municipality on monthly bases, as a results some ward committee members are demotivated. This research study concludes that Mbombela local municipality is not effectively implementing local government legislation in respect to public participation.
- Full Text:
- Date Issued: 2013
New ways of understanding: a governmentality analysis of basic education policy in post-apartheid South Africa
- Authors: Prinsloo, Estelle Helena
- Date: 2013
- Subjects: South Africa -- Department of Basic Education , Basic education -- Government policy -- Research -- South Africa , Post-apartheid era -- Education -- South Africa , Educational change -- Research -- South Africa , South Africa -- Social conditions
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:2751 , http://hdl.handle.net/10962/d1001384
- Description: Social problems that are identified by government policy are articulated in ways that confer the responsibility of their management onto the state. In this way, policy reform serves as a means to justify political rule, as the ‘answers’ to policy failures are located within the realm of state intervention. This role of policy is maintained by the traditional definition of policy as it enables policies to be presented as the outcome of ‘necessary’ actions taken by state institutions to better the wellbeing of citizens. Since 1994, mainstream research on basic education policy in South Africa has employed traditional understandings of policy and its function. In doing so, these inquiries have failed to question the very idea of policy itself. They have also neglected to identify the productive role played by policy in the practice of power. To illuminate the necessary limits of policy reform, an alternative approach to analyse basic education policy is necessary. This thesis premises policy as discourse and advances a governmentality analysis of basic education policy during the first fifteen years of democracy (1994-2009) in South Africa. By drawing on the work of Michel Foucault, the study argues that government – ‘those actions upon the actions of others’ – during this period in South Africa was informed by both a liberal and a neo-liberal mentality of rule. The tensions between these two rationalities contributed to the continuation of apartheid’s socio-economic inequalities in the postapartheid era; an outcome buttressed by the contradictory impulses within basic education policy. By considering policy as a productive translation of governmental reasoning, the boundaries of intervention for future policy reforms are highlighted. These show that the inequalities that were perpetuated during the first fifteen years of democracy justify policy responses similar to those responsible for their production
- Full Text:
- Date Issued: 2013
- Authors: Prinsloo, Estelle Helena
- Date: 2013
- Subjects: South Africa -- Department of Basic Education , Basic education -- Government policy -- Research -- South Africa , Post-apartheid era -- Education -- South Africa , Educational change -- Research -- South Africa , South Africa -- Social conditions
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:2751 , http://hdl.handle.net/10962/d1001384
- Description: Social problems that are identified by government policy are articulated in ways that confer the responsibility of their management onto the state. In this way, policy reform serves as a means to justify political rule, as the ‘answers’ to policy failures are located within the realm of state intervention. This role of policy is maintained by the traditional definition of policy as it enables policies to be presented as the outcome of ‘necessary’ actions taken by state institutions to better the wellbeing of citizens. Since 1994, mainstream research on basic education policy in South Africa has employed traditional understandings of policy and its function. In doing so, these inquiries have failed to question the very idea of policy itself. They have also neglected to identify the productive role played by policy in the practice of power. To illuminate the necessary limits of policy reform, an alternative approach to analyse basic education policy is necessary. This thesis premises policy as discourse and advances a governmentality analysis of basic education policy during the first fifteen years of democracy (1994-2009) in South Africa. By drawing on the work of Michel Foucault, the study argues that government – ‘those actions upon the actions of others’ – during this period in South Africa was informed by both a liberal and a neo-liberal mentality of rule. The tensions between these two rationalities contributed to the continuation of apartheid’s socio-economic inequalities in the postapartheid era; an outcome buttressed by the contradictory impulses within basic education policy. By considering policy as a productive translation of governmental reasoning, the boundaries of intervention for future policy reforms are highlighted. These show that the inequalities that were perpetuated during the first fifteen years of democracy justify policy responses similar to those responsible for their production
- Full Text:
- Date Issued: 2013
A strange counterpoint : classical music performance and identities in Grahamstown, South Africa
- Marais, Terence Wilmot Eugene
- Authors: Marais, Terence Wilmot Eugene
- Date: 2011
- Subjects: Music -- Western influences Music -- Performance -- Psychological aspects Music appreciation -- South Africa -- Grahamstown Music -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: vital:2677 , http://hdl.handle.net/10962/d1007491
- Description: This study investigates the perceptions of South African practitioners of Western European Art Music (WEAM), specifically as they relate to the value of WEAM in contemporary South African society. In exploring some of the connections between musical identity and national identity, it sets out to discover what value WEAM holds for a certain group of student pianists. Qualitative empirical data was collected in the form of in-depth, semi-structured interviews and questionnaire responses, and the findings point to numerous, nuanced expressions of self and varied intersections of the nation with musical identity in the life of the individual. Further, WEAM appears to represent a crucial point of identification for these individuals, in each case generating positive affirmations of the self.
- Full Text:
- Date Issued: 2011
- Authors: Marais, Terence Wilmot Eugene
- Date: 2011
- Subjects: Music -- Western influences Music -- Performance -- Psychological aspects Music appreciation -- South Africa -- Grahamstown Music -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: vital:2677 , http://hdl.handle.net/10962/d1007491
- Description: This study investigates the perceptions of South African practitioners of Western European Art Music (WEAM), specifically as they relate to the value of WEAM in contemporary South African society. In exploring some of the connections between musical identity and national identity, it sets out to discover what value WEAM holds for a certain group of student pianists. Qualitative empirical data was collected in the form of in-depth, semi-structured interviews and questionnaire responses, and the findings point to numerous, nuanced expressions of self and varied intersections of the nation with musical identity in the life of the individual. Further, WEAM appears to represent a crucial point of identification for these individuals, in each case generating positive affirmations of the self.
- Full Text:
- Date Issued: 2011
An art based support programme for the amelioration of general psychological distress in marginalised children in South Africa
- Authors: Armstrong, Meredith
- Date: 2011 , 2011-06-28
- Subjects: Art therapy for children Child mental health Group psychotherapy for children Abused children -- Mental health
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3096 , http://hdl.handle.net/10962/d1003730
- Description: This study aimed to construct, and implement an in-school "art expression" based programme designed to aid in mitigation of psychological stress, behavioural difficulties, and self-negativity frequently experienced by marginalised children. It was developed for application within schools that cater for children exposed to neglect and/or abuse resulting from poverty in South Africa. This programme outline was developed and implemented through intensive exploration and review of previously effective art therapy, art expressive methods and techniques in similar contexts, together with the knowledge and experience of a qualified art therapist and educational psychologist. Data was collected through open-ended informal qualitative interviews, observations, and photographs of artworks produced during sessions. These were then analysed in conjunction, using the content analysis method, visual interpretive measures and thematic analysis. This enquiry documented the process of art creation through "art expression", and its ability to ameliorate psychological difficulties affecting marginalised children in South Africa. Following the establishment of trust between the researchers and the participants, the results found that the use of different art modalities demonstrated predominantly positive results in varying degrees. It is hoped that this study can be used to further practical interventions of this nature in comparable milieus in South Africa.
- Full Text:
- Date Issued: 2011
- Authors: Armstrong, Meredith
- Date: 2011 , 2011-06-28
- Subjects: Art therapy for children Child mental health Group psychotherapy for children Abused children -- Mental health
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3096 , http://hdl.handle.net/10962/d1003730
- Description: This study aimed to construct, and implement an in-school "art expression" based programme designed to aid in mitigation of psychological stress, behavioural difficulties, and self-negativity frequently experienced by marginalised children. It was developed for application within schools that cater for children exposed to neglect and/or abuse resulting from poverty in South Africa. This programme outline was developed and implemented through intensive exploration and review of previously effective art therapy, art expressive methods and techniques in similar contexts, together with the knowledge and experience of a qualified art therapist and educational psychologist. Data was collected through open-ended informal qualitative interviews, observations, and photographs of artworks produced during sessions. These were then analysed in conjunction, using the content analysis method, visual interpretive measures and thematic analysis. This enquiry documented the process of art creation through "art expression", and its ability to ameliorate psychological difficulties affecting marginalised children in South Africa. Following the establishment of trust between the researchers and the participants, the results found that the use of different art modalities demonstrated predominantly positive results in varying degrees. It is hoped that this study can be used to further practical interventions of this nature in comparable milieus in South Africa.
- Full Text:
- Date Issued: 2011
Queens, pseudoqueens and laying workers reproductive competition in the Cape Honeybee (Apis mellifera capensis Eschscholtz)
- Authors: Muerrle, Thomas Martin
- Date: 2008
- Subjects: Honeybee Honeybee -- Reproduction
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5750 , http://hdl.handle.net/10962/d1005437
- Description: In honeybees (Apis mellifera L.) the queen monopolises reproduction. However, especially after queen loss, workers can lay eggs, but are unable to mate. They produce haploid male offspring (drones) from unfertilised eggs via arrhenotokous parthenogenesis. In contrast, workers of the honeybee subspecies Apis mellifera capensis Eschscholtz typically produce diploid female offspring from unfertilised eggs thelytokously. After queen loss and without queen-derived brood A. m. capensis colonies can successfully requeen from worker-derived brood. This, however, is a relatively rare event in wild populations. Moreover, workerderived queens were described to be smaller, more worker-like and reproductively inferior. On the other hand, the fixation of the thelytokous trait relies mainly on sufficient numbers of viable drones produced by worker-derived queens. Small numbers of reproductively inferior worker-derived queens in A. m. capensis populations would be clearly counterintuitive. It is therefore necessary to quantify the significance of worker-dependant queen rearing pathways on the individual (queen) and on population level.Reproductive inferiority of worker-derived queens could not be confirmed on the individual (queen) level when comparing parameters indicating potential reproductive success of queen- and worker-derived queens. Queen- and worker-derived queens clearly showed a congruent range of reproductive performance. In queen rearing preference tests, increased acceptance of worker-derived female larvae was exactly counterbalanced by increased mortality, resulting in an equal number of eclosing virgin queens from an equal number of grafts in both test groups. Larval survival and successful eclosion is a prerequisite for a queen’s reproductive success. I found no difference in eclosion success for queen- and worker-derived virgin queens, indicating a similar potential for reproductive success in both queen types. Assessments of the developmental patterns of colonies headed by both queen and worker-derived queens in long-term experiments revealed no significant differences in reproductive success. Colonies headed by queen-derived queens and colonies headed by worker-derived queens could not be separated when comparing the different developmental pathways observed or from differences in worker-force. Reproductive dominance in A. m. capensis appeared tobe determined by a function of relative compositional and absolute quantitative pheromonal patterns, where individuals, which produce compositionally most queen-like blends in highest quantities, occupy top positions. Queen- and worker-derived virgin queens occupied intermediate positions between pseudoqueens and mated queens. However, no significant differences between the pheromonal status of queen- and worker-derived virgin queens were observed, suggesting a similar range of reproductive dominance for both queen types. In behavioural bioassays queen- and worker-derived virgin queens appeared to be similarly attractive to clustering workers and to drones in a drone congregation area, indicating no differences in potential reproductive success for queens from both origins for those parameters. The significant influence of the queen substance 9-ODA on attractiveness to workers and drones was confirmed. Rare requeening events from worker-derived female brood in queenless A.m. capensis do not satisfactorily explain the fixation of the thelytokous trait at a population level. I observed A. m. capensis worker ovipositing into empty artificial queen cell cups in queen-right colonies. The queen was confined behind a queen excluder grid in a separate compartment of the colony, to imitate reduced pheromonal flow, similar to swarming or superseding colonies. Eggs oviposited by workers in artificial queen cell cups were readily accepted for queen rearing and successful eclosion of viable virgin queens was observed. Consequently I suggested an alternative worker-dependant reproductive pathway in A. m. capensis, which was never described before: In swarming or superseding queenright colonies, laying workers may directly compete with the queen for reproductive success by ovipositing (instead of the queen) into natural queen cell cups. At a population level this reproductive tactic may result in large numbers of worker-derived queens of high reproductive quality in natural populations of A. m. capensis.
- Full Text:
- Date Issued: 2008
- Authors: Muerrle, Thomas Martin
- Date: 2008
- Subjects: Honeybee Honeybee -- Reproduction
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5750 , http://hdl.handle.net/10962/d1005437
- Description: In honeybees (Apis mellifera L.) the queen monopolises reproduction. However, especially after queen loss, workers can lay eggs, but are unable to mate. They produce haploid male offspring (drones) from unfertilised eggs via arrhenotokous parthenogenesis. In contrast, workers of the honeybee subspecies Apis mellifera capensis Eschscholtz typically produce diploid female offspring from unfertilised eggs thelytokously. After queen loss and without queen-derived brood A. m. capensis colonies can successfully requeen from worker-derived brood. This, however, is a relatively rare event in wild populations. Moreover, workerderived queens were described to be smaller, more worker-like and reproductively inferior. On the other hand, the fixation of the thelytokous trait relies mainly on sufficient numbers of viable drones produced by worker-derived queens. Small numbers of reproductively inferior worker-derived queens in A. m. capensis populations would be clearly counterintuitive. It is therefore necessary to quantify the significance of worker-dependant queen rearing pathways on the individual (queen) and on population level.Reproductive inferiority of worker-derived queens could not be confirmed on the individual (queen) level when comparing parameters indicating potential reproductive success of queen- and worker-derived queens. Queen- and worker-derived queens clearly showed a congruent range of reproductive performance. In queen rearing preference tests, increased acceptance of worker-derived female larvae was exactly counterbalanced by increased mortality, resulting in an equal number of eclosing virgin queens from an equal number of grafts in both test groups. Larval survival and successful eclosion is a prerequisite for a queen’s reproductive success. I found no difference in eclosion success for queen- and worker-derived virgin queens, indicating a similar potential for reproductive success in both queen types. Assessments of the developmental patterns of colonies headed by both queen and worker-derived queens in long-term experiments revealed no significant differences in reproductive success. Colonies headed by queen-derived queens and colonies headed by worker-derived queens could not be separated when comparing the different developmental pathways observed or from differences in worker-force. Reproductive dominance in A. m. capensis appeared tobe determined by a function of relative compositional and absolute quantitative pheromonal patterns, where individuals, which produce compositionally most queen-like blends in highest quantities, occupy top positions. Queen- and worker-derived virgin queens occupied intermediate positions between pseudoqueens and mated queens. However, no significant differences between the pheromonal status of queen- and worker-derived virgin queens were observed, suggesting a similar range of reproductive dominance for both queen types. In behavioural bioassays queen- and worker-derived virgin queens appeared to be similarly attractive to clustering workers and to drones in a drone congregation area, indicating no differences in potential reproductive success for queens from both origins for those parameters. The significant influence of the queen substance 9-ODA on attractiveness to workers and drones was confirmed. Rare requeening events from worker-derived female brood in queenless A.m. capensis do not satisfactorily explain the fixation of the thelytokous trait at a population level. I observed A. m. capensis worker ovipositing into empty artificial queen cell cups in queen-right colonies. The queen was confined behind a queen excluder grid in a separate compartment of the colony, to imitate reduced pheromonal flow, similar to swarming or superseding colonies. Eggs oviposited by workers in artificial queen cell cups were readily accepted for queen rearing and successful eclosion of viable virgin queens was observed. Consequently I suggested an alternative worker-dependant reproductive pathway in A. m. capensis, which was never described before: In swarming or superseding queenright colonies, laying workers may directly compete with the queen for reproductive success by ovipositing (instead of the queen) into natural queen cell cups. At a population level this reproductive tactic may result in large numbers of worker-derived queens of high reproductive quality in natural populations of A. m. capensis.
- Full Text:
- Date Issued: 2008
An evaluation of the regulation and enforcement of trade mark and domain name rights in South Africa
- Authors: Maunganidze, Tendai
- Date: 2007
- Subjects: Trademarks -- Law and legislation -- South Africa Internet domain names -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3714 , http://hdl.handle.net/10962/d1007571
- Description: The conflict between trade marks and domain names has been a major subject of legal debate over the past few years. The issues arising from the relationship between trade marks and domain names reveal the difficulties associated with attempts to establish mechanisms to address the problems existing between them. Trade mark laws have been adopted to resolve the trade mark and domain name conflict, resulting in more conflict. Domain name registers have to date been constructed on the basis of first come first served. Given that the generic indicators are very general, it has been inevitable that problems would arise, particularly once the commercial potential of the Internet began to be realised. Unlike domain names, trade marks are protected in ways which are more precise. Trade marks may not be imitated either exactly or in a manner so similar that it is likely to confuse a significant portion of the public. It is possible for more than one enterprise to use the same trade mark in respect of different goods, although this is not possible with domain names. This disparity in objectives leads to two core problems. The first problem relates to cybersquatters who deliberately secure Top Level Domains (TLDs) containing the names or marks of well known enterprises in order to sell them later. The second problem relates to the rival claims between parties who have genuine reasons for wanting particular TLDs, and problems associated with the resolution of such claims. The disputes between parties with legitimate conflicting interests in domain names are often not equitably and effectively resolved, thus compromising the rights of domain name holders. There is great activity in the United States of America (USA) and the United Kingdom (UK) to provide a more substantial system of governing and regulating the Internet. There is a strong movement to provide methods of arbitrating conflicts between honest claims to TLDs which conflict either in Internet terms or in trade mark law. However, these difficult policies remain to be settled. South Africa's progress towards the establishment of an effective mechanism to govern and regulate the Internet has been hindered by the absence of a policy to resolve domain related trade mark disputes. South Africa only recently drafted the South African Regulations for Alternative Domain Name Dispute Resolution (zaADRR), although the regulations have not yet been adopted. Therefore South African parties to domain name disputes continue to find solutions to their problems through the court system or foreign dispute resolution policies. The purpose of this study is firstly to examine and to comment on the basic issues of trade mark law and domain names in this area, with particular reference to South Africa, and secondly to examine the mechanisms in place for the resolution of trade mark and domain name disputes and to highlight the issues that flow from that. An additional purpose of this study is to discuss the policies of the dispute resolution mechanisms and to suggest how these policies can be improved.
- Full Text:
- Date Issued: 2007
An evaluation of the regulation and enforcement of trade mark and domain name rights in South Africa
- Authors: Maunganidze, Tendai
- Date: 2007
- Subjects: Trademarks -- Law and legislation -- South Africa Internet domain names -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3714 , http://hdl.handle.net/10962/d1007571
- Description: The conflict between trade marks and domain names has been a major subject of legal debate over the past few years. The issues arising from the relationship between trade marks and domain names reveal the difficulties associated with attempts to establish mechanisms to address the problems existing between them. Trade mark laws have been adopted to resolve the trade mark and domain name conflict, resulting in more conflict. Domain name registers have to date been constructed on the basis of first come first served. Given that the generic indicators are very general, it has been inevitable that problems would arise, particularly once the commercial potential of the Internet began to be realised. Unlike domain names, trade marks are protected in ways which are more precise. Trade marks may not be imitated either exactly or in a manner so similar that it is likely to confuse a significant portion of the public. It is possible for more than one enterprise to use the same trade mark in respect of different goods, although this is not possible with domain names. This disparity in objectives leads to two core problems. The first problem relates to cybersquatters who deliberately secure Top Level Domains (TLDs) containing the names or marks of well known enterprises in order to sell them later. The second problem relates to the rival claims between parties who have genuine reasons for wanting particular TLDs, and problems associated with the resolution of such claims. The disputes between parties with legitimate conflicting interests in domain names are often not equitably and effectively resolved, thus compromising the rights of domain name holders. There is great activity in the United States of America (USA) and the United Kingdom (UK) to provide a more substantial system of governing and regulating the Internet. There is a strong movement to provide methods of arbitrating conflicts between honest claims to TLDs which conflict either in Internet terms or in trade mark law. However, these difficult policies remain to be settled. South Africa's progress towards the establishment of an effective mechanism to govern and regulate the Internet has been hindered by the absence of a policy to resolve domain related trade mark disputes. South Africa only recently drafted the South African Regulations for Alternative Domain Name Dispute Resolution (zaADRR), although the regulations have not yet been adopted. Therefore South African parties to domain name disputes continue to find solutions to their problems through the court system or foreign dispute resolution policies. The purpose of this study is firstly to examine and to comment on the basic issues of trade mark law and domain names in this area, with particular reference to South Africa, and secondly to examine the mechanisms in place for the resolution of trade mark and domain name disputes and to highlight the issues that flow from that. An additional purpose of this study is to discuss the policies of the dispute resolution mechanisms and to suggest how these policies can be improved.
- Full Text:
- Date Issued: 2007
Exploring learners' mathematical understanding through an analysis of their solution strategies
- Authors: Penlington, Thomas Helm
- Date: 2005
- Subjects: Mathematics -- Study and teaching (Elementary) Mathematics -- Problems, exercises, etc. Problem solving -- Study and teaching Reasoning Mathematical ability
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1934 , http://hdl.handle.net/10962/d1007642
- Description: The purpose of this study is to investigate various solution strategies employed by Grade 7 learners and their teachers when solving a given set of mathematical tasks. This study is oriented in an interpretive paradigm and is characterised by qualitative methods. The research, set in nine schools in the Eastern Cape, was carried out with nine learners and their mathematics teachers and was designed around two phases. The research tools consisted of a set of 12 tasks that were modelled after the Third International Mathematics and Science Study (TIMSS), and a process of clinical interviews that interrogated the solution strategies that were used in solving the 12 tasks. Aspects of grounded theory were used in the analysis of the data. The study reveals that in most tasks, learners relied heavily on procedural understanding at the expense of conceptual understanding. It also emphasises that the solution strategies adopted by learners, particularly whole number operations, were consistent with those strategies used by their teachers. Both learners and teachers favoured using the traditional, standard algorithm strategies and appeared to have learned these algorithms in isolation from concepts, failing to relate them to understanding. Another important finding was that there was evidence to suggest that some learners and teachers did employ their own constructed solution strategies. They were able to make sense of the problems and to 'mathematize' effectively and reason mathematically. An interesting outcome of the study shows that participants were more proficient in solving word problems than mathematical computations. This is in contrast to existing research on word problems, where it is shown that teachers find them difficult to teach and learners find them difficult to understand. The findings of this study also highlight issues for mathematics teachers to consider when dealing with computations and word problems involving number sense and other problem solving type problems.
- Full Text:
- Date Issued: 2005
- Authors: Penlington, Thomas Helm
- Date: 2005
- Subjects: Mathematics -- Study and teaching (Elementary) Mathematics -- Problems, exercises, etc. Problem solving -- Study and teaching Reasoning Mathematical ability
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1934 , http://hdl.handle.net/10962/d1007642
- Description: The purpose of this study is to investigate various solution strategies employed by Grade 7 learners and their teachers when solving a given set of mathematical tasks. This study is oriented in an interpretive paradigm and is characterised by qualitative methods. The research, set in nine schools in the Eastern Cape, was carried out with nine learners and their mathematics teachers and was designed around two phases. The research tools consisted of a set of 12 tasks that were modelled after the Third International Mathematics and Science Study (TIMSS), and a process of clinical interviews that interrogated the solution strategies that were used in solving the 12 tasks. Aspects of grounded theory were used in the analysis of the data. The study reveals that in most tasks, learners relied heavily on procedural understanding at the expense of conceptual understanding. It also emphasises that the solution strategies adopted by learners, particularly whole number operations, were consistent with those strategies used by their teachers. Both learners and teachers favoured using the traditional, standard algorithm strategies and appeared to have learned these algorithms in isolation from concepts, failing to relate them to understanding. Another important finding was that there was evidence to suggest that some learners and teachers did employ their own constructed solution strategies. They were able to make sense of the problems and to 'mathematize' effectively and reason mathematically. An interesting outcome of the study shows that participants were more proficient in solving word problems than mathematical computations. This is in contrast to existing research on word problems, where it is shown that teachers find them difficult to teach and learners find them difficult to understand. The findings of this study also highlight issues for mathematics teachers to consider when dealing with computations and word problems involving number sense and other problem solving type problems.
- Full Text:
- Date Issued: 2005
The adsorption of chelating reagents on oxide minerals
- Bryson, Michael Andrew Walker
- Authors: Bryson, Michael Andrew Walker
- Date: 1986
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:20969 , http://hdl.handle.net/10962/5729
- Description: This work constitutes a fundamental study of the interaction between chelating reagents and oxide minerals . The adsorption mechanisms have been elucidated for most of the systems generated by the oxides of copper(II) or iron(III) and chelating reagents octyl hydroxamate, N-phenylbenzohydroxamate, salicylaldoxime, 5-nitrosalicylaldoxime or 8-hydroxyquinoline. The results of the preliminary work on one of the systems, viz. the oxide-hydroxamate system, indicated that the classical type adsorption process, in which the reagent forms a uniform layer of chelate over the oxide surface was not applicable. Rather, the adsorption occurred via the formation of a discrete metal-chelate precipitate at the oxide surface. In order to better understand the associated with copper (II) oxide, adsorption process the oxide was recrystallized to produce a coarser material with a more uniform surface. This allowed the oxide surface to be viewed under the scanning electron microscope and also enabled the relative concentration of "surface" and "bulk" chelate to be assessed. A detailed investigation of the effect of the system variables; pH, conditioning period, concentration, temperature, surface area and dispersing reagent on the rate of precipitation of the copper chelate species of general form, Cu(chel)2' was made. In addition the chemical nature of the adsorbed species and the structural form of the precipitates were determined with the aid of infra-red spectroscopy and the scanning electron microscope. On the basis of these results a model has been formulated for the adsorption processes. In this model the adsorption dissolution, is considered to occur in stages: 1. Oxide dissolution, 2. metal complex formation, 3. Metal chelate precipitation at the oxide surface and 4. “bulk” chelate formation by post-precipitation processes. The precipitation process was examined in more detail by the study of the adsorption of chelate on copper metal. The results of this study showed that it was possible to relate the structural type of precipitate formed, ie. fibrous or platelike, to the degree of supersaturation of the metal complex in solution. Furthermore, it was found that the precipitate structure determined whether it remained attached to the surface or detached. Contact angle measurements of air bubbles on copper metal conditioned with chelate were related to the adsorption results in an attempt to isolate the optimum conditions for flotation of oxide minerals.
- Full Text:
- Date Issued: 1986
- Authors: Bryson, Michael Andrew Walker
- Date: 1986
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:20969 , http://hdl.handle.net/10962/5729
- Description: This work constitutes a fundamental study of the interaction between chelating reagents and oxide minerals . The adsorption mechanisms have been elucidated for most of the systems generated by the oxides of copper(II) or iron(III) and chelating reagents octyl hydroxamate, N-phenylbenzohydroxamate, salicylaldoxime, 5-nitrosalicylaldoxime or 8-hydroxyquinoline. The results of the preliminary work on one of the systems, viz. the oxide-hydroxamate system, indicated that the classical type adsorption process, in which the reagent forms a uniform layer of chelate over the oxide surface was not applicable. Rather, the adsorption occurred via the formation of a discrete metal-chelate precipitate at the oxide surface. In order to better understand the associated with copper (II) oxide, adsorption process the oxide was recrystallized to produce a coarser material with a more uniform surface. This allowed the oxide surface to be viewed under the scanning electron microscope and also enabled the relative concentration of "surface" and "bulk" chelate to be assessed. A detailed investigation of the effect of the system variables; pH, conditioning period, concentration, temperature, surface area and dispersing reagent on the rate of precipitation of the copper chelate species of general form, Cu(chel)2' was made. In addition the chemical nature of the adsorbed species and the structural form of the precipitates were determined with the aid of infra-red spectroscopy and the scanning electron microscope. On the basis of these results a model has been formulated for the adsorption processes. In this model the adsorption dissolution, is considered to occur in stages: 1. Oxide dissolution, 2. metal complex formation, 3. Metal chelate precipitation at the oxide surface and 4. “bulk” chelate formation by post-precipitation processes. The precipitation process was examined in more detail by the study of the adsorption of chelate on copper metal. The results of this study showed that it was possible to relate the structural type of precipitate formed, ie. fibrous or platelike, to the degree of supersaturation of the metal complex in solution. Furthermore, it was found that the precipitate structure determined whether it remained attached to the surface or detached. Contact angle measurements of air bubbles on copper metal conditioned with chelate were related to the adsorption results in an attempt to isolate the optimum conditions for flotation of oxide minerals.
- Full Text:
- Date Issued: 1986
Protest in fiction : an approach to Alex la Guma
- Cornwell, David Gareth Napier
- Authors: Cornwell, David Gareth Napier
- Date: 1979
- Subjects: La Guma, Alex , South African literature (English) -- Black authors -- History and criticism , Protest literature, South African (English) -- History and criticism
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:2169 , http://hdl.handle.net/10962/d1001820
- Description: From Introduction: Thus for the black South African, the act of creative writing is inescapably a form of political action, and unless he turns his back on the reality which confronts him and retreats into a private imaginary world, it is also a form of social action, Yet Ezekiel Mphahlele has rightly cautioned that "creating an imaginary world" can never be an effective substitute for social act ion . Composing fictions about social and political problems is an indubitably oblique way of seeking a solution to them, and even the tendentious recreation of reality is only a metaphor for its actual transformation. Protest writing in South Africa is paradoxically a form of social action which is also only a parasitical imitation of social action, and therefore its avoidance . The freedom of literary creation described above is ambiguously not only a freedom to express reality, but also a freedom from the constraints of reality. And this suggests why the outlaw was such an important symbol to an earlier generation of rather more self-conscious writers.
- Full Text:
- Date Issued: 1979
- Authors: Cornwell, David Gareth Napier
- Date: 1979
- Subjects: La Guma, Alex , South African literature (English) -- Black authors -- History and criticism , Protest literature, South African (English) -- History and criticism
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:2169 , http://hdl.handle.net/10962/d1001820
- Description: From Introduction: Thus for the black South African, the act of creative writing is inescapably a form of political action, and unless he turns his back on the reality which confronts him and retreats into a private imaginary world, it is also a form of social action, Yet Ezekiel Mphahlele has rightly cautioned that "creating an imaginary world" can never be an effective substitute for social act ion . Composing fictions about social and political problems is an indubitably oblique way of seeking a solution to them, and even the tendentious recreation of reality is only a metaphor for its actual transformation. Protest writing in South Africa is paradoxically a form of social action which is also only a parasitical imitation of social action, and therefore its avoidance . The freedom of literary creation described above is ambiguously not only a freedom to express reality, but also a freedom from the constraints of reality. And this suggests why the outlaw was such an important symbol to an earlier generation of rather more self-conscious writers.
- Full Text:
- Date Issued: 1979
A contribution to the benthic biology of some southern African lakes
- Authors: Boltt, R E
- Date: 1969
- Subjects: Aquatic biology -- Africa, Southern Benthos -- Africa, Southern Lake animals -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5836 , http://hdl.handle.net/10962/d1009521
- Description: The benthos of Lake Sibayi, Lake Nhlange, Lake Shengesa and Lake Sifungwe has been sampled by means of a van Veen grab of bite area 0.225m². Except for Lake Shengesa, the substrates of the lakes have been investigated visually by SCUBA divers. Some quantitative sampling, using underwater techniques, has been carried out in Lake Sibayi. In general, the substrate of the lakes consisted of two types, either fine sand with an average particle size of 3.2 phi, or mud with a median phi value of less than 6. The sandy substrata was usually rich in fauna, and the mud usually poor. Lake Sibayi , which is freshwater (135 ppm Cl¯) has estuarine and freshwater species in the benthos. Some of the species, notably Grandidierella lignorum and Apseudes digitalis, show an uneven pattern of distribution with respect to depth. Lake Nhlange is a brackwater lake (3.4‰ salinity) and has mainly an estuarine fauna. Many of the species are different from those found in Lake Sibayi. There is some evidence that the benthic fauna of the lake has increased its range in depth in the years following a flood in January 1966. Only chironomid larvae were found in the benthos of Lake Shengesa. The greater part of the substrate of this lake consisted of a highly organic mud mainly derived from burnt grassland around the periphery of the lake. Lake Sifungwe, which is connected to Lake Nhlange, has a halocline at about 9 metres. The fauna of the benthos has more species than lake Nhlange. There is some evidence to suggest that LGC fauna invades deeper water in summer, and is driven into shallower water in winter because of the fluctuating level of anaerobic conditions below the discontinuity layer. The benthic fauna of the lakes has been compared with that of the estuaries reported on by the Cape Town Ecological Survey. experimental studies on G. lignorum, a species present in Lake Sibayi, suggested that the physiological responses of material from an estuary normally at 35‰ salinity (Kowie River estuary) and from lakes which are normally of low salinity (Groenvlei 2.5‰ salinity, Lake Sibayi) were not different. Studies on substrate choice, and pressure, indicated that these factors do not affect the distribution pattern of G. lignorum in the substrate. Studies on light orientation responses and the effects of rates of carbon dioxide increase of about 20 mm HgC0₂/hr or more, suggest that these may be the principle factors affecting the distribution of G. lignorum in the benthos of Lake Sibayi. Some supporting evidence for the presence of changing pC0₂ has been found. A discussion of the importance of dynamic events at the substrate/water interface is given.
- Full Text:
- Date Issued: 1969
- Authors: Boltt, R E
- Date: 1969
- Subjects: Aquatic biology -- Africa, Southern Benthos -- Africa, Southern Lake animals -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5836 , http://hdl.handle.net/10962/d1009521
- Description: The benthos of Lake Sibayi, Lake Nhlange, Lake Shengesa and Lake Sifungwe has been sampled by means of a van Veen grab of bite area 0.225m². Except for Lake Shengesa, the substrates of the lakes have been investigated visually by SCUBA divers. Some quantitative sampling, using underwater techniques, has been carried out in Lake Sibayi. In general, the substrate of the lakes consisted of two types, either fine sand with an average particle size of 3.2 phi, or mud with a median phi value of less than 6. The sandy substrata was usually rich in fauna, and the mud usually poor. Lake Sibayi , which is freshwater (135 ppm Cl¯) has estuarine and freshwater species in the benthos. Some of the species, notably Grandidierella lignorum and Apseudes digitalis, show an uneven pattern of distribution with respect to depth. Lake Nhlange is a brackwater lake (3.4‰ salinity) and has mainly an estuarine fauna. Many of the species are different from those found in Lake Sibayi. There is some evidence that the benthic fauna of the lake has increased its range in depth in the years following a flood in January 1966. Only chironomid larvae were found in the benthos of Lake Shengesa. The greater part of the substrate of this lake consisted of a highly organic mud mainly derived from burnt grassland around the periphery of the lake. Lake Sifungwe, which is connected to Lake Nhlange, has a halocline at about 9 metres. The fauna of the benthos has more species than lake Nhlange. There is some evidence to suggest that LGC fauna invades deeper water in summer, and is driven into shallower water in winter because of the fluctuating level of anaerobic conditions below the discontinuity layer. The benthic fauna of the lakes has been compared with that of the estuaries reported on by the Cape Town Ecological Survey. experimental studies on G. lignorum, a species present in Lake Sibayi, suggested that the physiological responses of material from an estuary normally at 35‰ salinity (Kowie River estuary) and from lakes which are normally of low salinity (Groenvlei 2.5‰ salinity, Lake Sibayi) were not different. Studies on substrate choice, and pressure, indicated that these factors do not affect the distribution pattern of G. lignorum in the substrate. Studies on light orientation responses and the effects of rates of carbon dioxide increase of about 20 mm HgC0₂/hr or more, suggest that these may be the principle factors affecting the distribution of G. lignorum in the benthos of Lake Sibayi. Some supporting evidence for the presence of changing pC0₂ has been found. A discussion of the importance of dynamic events at the substrate/water interface is given.
- Full Text:
- Date Issued: 1969
The influence of temperature in the ecology of the intermediate host snails of Schistosoma and Fasciola (Trematoda) in southern Rhodesia
- Authors: Shiff, Clive Julian
- Date: 1963
- Subjects: Schistosoma , Schistosomiasis , Fasciola , Snails -- Zimbabwe , Trematoda
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5881 , http://hdl.handle.net/10962/d1013208
- Description: The influence of temperature on the bionomics of Bulinus (Physopsis) globosus, Biomphalaria pfeifferi and Lymnaea natalensis has been studied both in the laboratory under controlled conditions and in the field under normal seasonal influences. Field studies were carried out in two different localities, one a semi-permanent pond and the other a temporary waterbody. For this purpose a sampling implement was developed. The results show the seasonal progression of these populations both with respect to estimated numbers and the size distribution of the snails. The rate of actual increase at different seasons was calculated for the three species where the data were sufficient. In the laboratory the snails were maintained at various temperatures, other conditions being kept standard. Daily records of mortality and fecundity of various cohorts reared from the egg stage enabled the compilation of life tables fof the speciesand from these data were calcualted the intrinsic rate of natural increase and other parameters. Effects of crowding in aquaria were studied. From the data obtained in the laboratory it was possible to predict the distribution and population potential for each species for snail of various environmental conditions. These predictions were, in fact, confirmed by field observation.
- Full Text:
- Date Issued: 1963
- Authors: Shiff, Clive Julian
- Date: 1963
- Subjects: Schistosoma , Schistosomiasis , Fasciola , Snails -- Zimbabwe , Trematoda
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5881 , http://hdl.handle.net/10962/d1013208
- Description: The influence of temperature on the bionomics of Bulinus (Physopsis) globosus, Biomphalaria pfeifferi and Lymnaea natalensis has been studied both in the laboratory under controlled conditions and in the field under normal seasonal influences. Field studies were carried out in two different localities, one a semi-permanent pond and the other a temporary waterbody. For this purpose a sampling implement was developed. The results show the seasonal progression of these populations both with respect to estimated numbers and the size distribution of the snails. The rate of actual increase at different seasons was calculated for the three species where the data were sufficient. In the laboratory the snails were maintained at various temperatures, other conditions being kept standard. Daily records of mortality and fecundity of various cohorts reared from the egg stage enabled the compilation of life tables fof the speciesand from these data were calcualted the intrinsic rate of natural increase and other parameters. Effects of crowding in aquaria were studied. From the data obtained in the laboratory it was possible to predict the distribution and population potential for each species for snail of various environmental conditions. These predictions were, in fact, confirmed by field observation.
- Full Text:
- Date Issued: 1963
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