Economic security and the social science literature on teenage pregnancy in South Africa
- Authors: Macleod, Catriona I
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6253 , http://hdl.handle.net/10962/d1007871
- Description: Feminists have argued that the association made between teenage childbearing and long-term lower socioeconomic status hides a multitude of socially constructed inequalities. I extend this position by analysing how the association is linked in the South African literature on teenage pregnancy to economic security. I utilise Foucault’s conceptualization of the method of security. Security refers to institutions and practices that defend and maintain a national population as well as secure the economic, demographic, and social processes of that population. I analyse how the traits of the method of security are deployed with regard to teenage pregnancy; how reproductive adolescents are viewed as disrupting the production of the economic self and fracturing population control, thereby threatening economic security; and how the invocation of economic security allows for the legitimation of various regulatory practices. , Rhodes University
- Full Text:
- Date Issued: 2002
- Authors: Macleod, Catriona I
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6253 , http://hdl.handle.net/10962/d1007871
- Description: Feminists have argued that the association made between teenage childbearing and long-term lower socioeconomic status hides a multitude of socially constructed inequalities. I extend this position by analysing how the association is linked in the South African literature on teenage pregnancy to economic security. I utilise Foucault’s conceptualization of the method of security. Security refers to institutions and practices that defend and maintain a national population as well as secure the economic, demographic, and social processes of that population. I analyse how the traits of the method of security are deployed with regard to teenage pregnancy; how reproductive adolescents are viewed as disrupting the production of the economic self and fracturing population control, thereby threatening economic security; and how the invocation of economic security allows for the legitimation of various regulatory practices. , Rhodes University
- Full Text:
- Date Issued: 2002
Effect of selected physical and production traits on the tick burdens of beef cattle
- Authors: Botha, Theunis Christoffel
- Date: 2002
- Subjects: Beef cattle -- Breeding
- Language: English
- Type: Thesis , Masters , MTech (Agricultural Management)
- Identifier: vital:10966 , http://hdl.handle.net/10948/91 , Beef cattle -- Breeding
- Description: The objective of this study was to determine the effect of selected traits such as age, sex, body weight, body length and height, body condition score (BCS), coatscore (CS), skin thickness and average skin surface temperature on tick burdens in beef cattle. Bonsmara cattle (n= 143) were used to measure visible tick counts, body condition score, coat score, skin thickness, body height and length, body weight, body surface temperature, gender and inter calving period. Measurements were taken from April to December. All animals were managed extensively on natural and cultivated pastures near George in the Southern Cape. Female animals had significantly (p<0.05) greater tick infestation (37.98±2.7) compared to male animals (16.52±1.2). Age was a significant factor (p<0.001) with the younger animals below two years having (46.40±5.26) more ticks than those of two years and older (20.15±2.44). A significant negative correlation (p<0.001; -0.29) was reported between the infestation of ticks on the animals and the age of the animal. Animals with an average body weight below 250kg had 42% (p<0.05) more ticks compared to animals with a body weight above 250kg. Age of the animal and weight were highly correlated (r= 0.70); p<0.001), while the correlation between the number of ticks per cow and the mean weight was negatively correlated (r= -0.37; p<0.001). Skin surface temperature significantly influenced tick infestation on the animals (p<0.001). The degree of infestation increased as body surface temperature exceeded 30º C. Coat score, skin thickness, body condition score and inter calving period did not significantly influence tick infestation on the animals. The infestation of ticks on the animals were significantly influenced by body height (p<0.019) and body length (p<0.001). Animals smaller than a 130cm in height had a significantly (p<0.05) greater tick infestation (36.5±5) compared to animals taller than 130cm (21.2±1.5). This trend was also observed for body length. Animals with a body length shorter than 145cm had a greater (p<0.05) average tick infestation of 41.3±4.5 compared to 23.2±1.3 to animals longer than 145cm, indicating a 44% greater tick infestation in favour of the shorter animals. For increased production and tick resistance animals should have smoother coats and be able to dissipate heat effectively.
- Full Text:
- Date Issued: 2002
- Authors: Botha, Theunis Christoffel
- Date: 2002
- Subjects: Beef cattle -- Breeding
- Language: English
- Type: Thesis , Masters , MTech (Agricultural Management)
- Identifier: vital:10966 , http://hdl.handle.net/10948/91 , Beef cattle -- Breeding
- Description: The objective of this study was to determine the effect of selected traits such as age, sex, body weight, body length and height, body condition score (BCS), coatscore (CS), skin thickness and average skin surface temperature on tick burdens in beef cattle. Bonsmara cattle (n= 143) were used to measure visible tick counts, body condition score, coat score, skin thickness, body height and length, body weight, body surface temperature, gender and inter calving period. Measurements were taken from April to December. All animals were managed extensively on natural and cultivated pastures near George in the Southern Cape. Female animals had significantly (p<0.05) greater tick infestation (37.98±2.7) compared to male animals (16.52±1.2). Age was a significant factor (p<0.001) with the younger animals below two years having (46.40±5.26) more ticks than those of two years and older (20.15±2.44). A significant negative correlation (p<0.001; -0.29) was reported between the infestation of ticks on the animals and the age of the animal. Animals with an average body weight below 250kg had 42% (p<0.05) more ticks compared to animals with a body weight above 250kg. Age of the animal and weight were highly correlated (r= 0.70); p<0.001), while the correlation between the number of ticks per cow and the mean weight was negatively correlated (r= -0.37; p<0.001). Skin surface temperature significantly influenced tick infestation on the animals (p<0.001). The degree of infestation increased as body surface temperature exceeded 30º C. Coat score, skin thickness, body condition score and inter calving period did not significantly influence tick infestation on the animals. The infestation of ticks on the animals were significantly influenced by body height (p<0.019) and body length (p<0.001). Animals smaller than a 130cm in height had a significantly (p<0.05) greater tick infestation (36.5±5) compared to animals taller than 130cm (21.2±1.5). This trend was also observed for body length. Animals with a body length shorter than 145cm had a greater (p<0.05) average tick infestation of 41.3±4.5 compared to 23.2±1.3 to animals longer than 145cm, indicating a 44% greater tick infestation in favour of the shorter animals. For increased production and tick resistance animals should have smoother coats and be able to dissipate heat effectively.
- Full Text:
- Date Issued: 2002
Effects of axial ligands on the photophysical properties of silicon octaphenoxyphthalocyanine
- Maree, M David, Nyokong, Tebello, Suhling, Klaus, Phillips, David
- Authors: Maree, M David , Nyokong, Tebello , Suhling, Klaus , Phillips, David
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289582 , vital:56651 , xlink:href="https://doi.org/10.1142/S1088424602000452"
- Description: The photochemistry and photophysics of six axially substituted silicon phthalocyanines are reported and show the importance of the axial groups in the photochemistry of these compounds. The fluorescence quantum yields are especially affected by the axial ligand. A very good correlation was found for the experimentally determined fluorescence lifetimes and the theoretically determined lifetimes using the Strickler-Berg equation for the unaggregated molecules.
- Full Text:
- Date Issued: 2002
- Authors: Maree, M David , Nyokong, Tebello , Suhling, Klaus , Phillips, David
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289582 , vital:56651 , xlink:href="https://doi.org/10.1142/S1088424602000452"
- Description: The photochemistry and photophysics of six axially substituted silicon phthalocyanines are reported and show the importance of the axial groups in the photochemistry of these compounds. The fluorescence quantum yields are especially affected by the axial ligand. A very good correlation was found for the experimentally determined fluorescence lifetimes and the theoretically determined lifetimes using the Strickler-Berg equation for the unaggregated molecules.
- Full Text:
- Date Issued: 2002
Effects of Axial Ligands on the Photosensitising Properties of Silicon Octaphenoxyphthalocyanines
- Authors: Maree, Machiel David
- Date: 2002
- Subjects: Ligands , Photochemotherapy , Phthalocyanines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4553 , http://hdl.handle.net/10962/d1018246
- Description: Various axially substituted Silicon octaphenoxyphthalocyanines were synthesised as potential photosensitisers in the photodynamic therapy of cancer. Conventional reflux reactions were used for synthesis as well as new microwave irradiation reactions, wherein the reaction times were decreased tenfold with a marginal increase in reaction yield and product purity. An interesting series of oligomeric (dimer to a nonamer) silicon octaphenoxyphthalocyanines were also successfully synthesised in a reaction similar to polymerisation reactions. These compounds were found to undergo an axial ligand transformation upon irradiation with red light (> 600 nm) in dimethylsulphoxide solution. All the ligands were transformed into the dihydroxy silicon octaphenoxyphthalocyanine with varying degrees of phototransformation quantum yields ranging in order from 10⁻³ to 10⁻⁵ depending on the axial ligand involved. During and after axial ligand transformations a photodegredation of the dihydroxy silicon octaphenoxy phthalocyanine was observed upon continued irradiation. The oligomers were found to undergo the same axial ligand transformation process with a phototransformation quantum yield of 10⁻⁵ The singlet oxygen quantum yields of the unaggregated monomeric silicon octaphenoxy phthalocyanines were all found to be approximately 0.2 with the exception of a compound with two (trihexyl)siloxy axial substituents that had a singlet oxygen quantum yield of approximately 0.4 in dimethylsulphoxide solutions. The oligomers showed a surprising trend of an increase in singlet oxygen quantum yield with an increase in phthalocyanine ring number up to the pentamer and then a dramatic decrease to the nonamer. The triplet quantum yield and triplet lifetime were determined by laser flash photolysis for selected compounds and no correlation was observed with any of these properties and the singlet oxygen quantum yields. These selected compounds all fluoresce and a very good correlation was found between the fluorescence lifetimes determined experimentally by laser photolysis and the Strickler-Berg equation for the non-aggregated compounds. Electrochemical measurements also indicate the importance of the axial ligands upon the behaviour of the phthalocyanines as cyclic voltammetric behaviour was determined by the nature of the axial ligand.
- Full Text:
- Date Issued: 2002
- Authors: Maree, Machiel David
- Date: 2002
- Subjects: Ligands , Photochemotherapy , Phthalocyanines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4553 , http://hdl.handle.net/10962/d1018246
- Description: Various axially substituted Silicon octaphenoxyphthalocyanines were synthesised as potential photosensitisers in the photodynamic therapy of cancer. Conventional reflux reactions were used for synthesis as well as new microwave irradiation reactions, wherein the reaction times were decreased tenfold with a marginal increase in reaction yield and product purity. An interesting series of oligomeric (dimer to a nonamer) silicon octaphenoxyphthalocyanines were also successfully synthesised in a reaction similar to polymerisation reactions. These compounds were found to undergo an axial ligand transformation upon irradiation with red light (> 600 nm) in dimethylsulphoxide solution. All the ligands were transformed into the dihydroxy silicon octaphenoxyphthalocyanine with varying degrees of phototransformation quantum yields ranging in order from 10⁻³ to 10⁻⁵ depending on the axial ligand involved. During and after axial ligand transformations a photodegredation of the dihydroxy silicon octaphenoxy phthalocyanine was observed upon continued irradiation. The oligomers were found to undergo the same axial ligand transformation process with a phototransformation quantum yield of 10⁻⁵ The singlet oxygen quantum yields of the unaggregated monomeric silicon octaphenoxy phthalocyanines were all found to be approximately 0.2 with the exception of a compound with two (trihexyl)siloxy axial substituents that had a singlet oxygen quantum yield of approximately 0.4 in dimethylsulphoxide solutions. The oligomers showed a surprising trend of an increase in singlet oxygen quantum yield with an increase in phthalocyanine ring number up to the pentamer and then a dramatic decrease to the nonamer. The triplet quantum yield and triplet lifetime were determined by laser flash photolysis for selected compounds and no correlation was observed with any of these properties and the singlet oxygen quantum yields. These selected compounds all fluoresce and a very good correlation was found between the fluorescence lifetimes determined experimentally by laser photolysis and the Strickler-Berg equation for the non-aggregated compounds. Electrochemical measurements also indicate the importance of the axial ligands upon the behaviour of the phthalocyanines as cyclic voltammetric behaviour was determined by the nature of the axial ligand.
- Full Text:
- Date Issued: 2002
Effects of substituents on the photosensitizing and electrocatalytic properties of phthalocyanines
- Authors: Maree, Suzanne Elizabeth
- Date: 2002
- Subjects: Phthalocyanines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4554 , http://hdl.handle.net/10962/d1018247
- Description: In this work a selection of octasubstituted phthalocyaninato Zinc, Ge(IV) and Sn(IV) complexes were synthesized for possible use in photodynamic therapy and their photochemistry, photophysics and electrochemistry studied. Third-generation complexes containing steroids, e.g. cholesterol and estrone, were synthesized to improve tumour selectivity. The zinc phthalocyanine complexes (ZnPc) showed that complexes containing electron-donating groups have higher photostability. Germanium phthalocyanine complexes (GePc) undergo phototransformation rather than direct photobleaching and the tin phthalocyanine complexes (SnPc) undergo photobleaching mediated by photoreduction of the phthalocyanine ring. Singlet oxygen production showed increased in the following order: GePc>SnPc>ZnPc. Triplet lifetimes of the GePc (168-340μs) are very similar to that of the ZnPc (197 - 366μs), but the triplet lifetimes of the SnPc are ten fold shorter (10 - 32μs ). Triplet quantum yields are higher for the GePc (0.20 - 0.50) and SnPc (0.08 - 0.45) than for the ZnPc (0.02 - 0.25). Fluorescence lifetimes of GePc ( 4.0 - 5.1 ns) are significantly longer than that of ZnPc (1.9 - 3.0 ns) and SnPc (0.2 - 0.4 ns). Fluorescence quantum yields decrease in the following order: GePc(0.21-0.31)>ZnPc(0.02-0.21)>SnPc(0.02- 0.06). Ring-substituted cobalt phthalocyanine complexes of the form CoPc(R)4 (R= NH2, N02, C(CH3)3, S03H and COOH) are compared for their catalytic activities towards the oxidation of cysteine. The potential for the electrocatalytic oxidation of cysteine is closely related to the Com/Co11 couple of the CoPc(R)4 complexes in acidic media and to the Con/Co1 couple in basic media. The catalytic current and the oxidation potential for cysteine are dependent on the pH of the solution, the potential becoming less positive and the currents increasing with increase in pH.
- Full Text:
- Date Issued: 2002
- Authors: Maree, Suzanne Elizabeth
- Date: 2002
- Subjects: Phthalocyanines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4554 , http://hdl.handle.net/10962/d1018247
- Description: In this work a selection of octasubstituted phthalocyaninato Zinc, Ge(IV) and Sn(IV) complexes were synthesized for possible use in photodynamic therapy and their photochemistry, photophysics and electrochemistry studied. Third-generation complexes containing steroids, e.g. cholesterol and estrone, were synthesized to improve tumour selectivity. The zinc phthalocyanine complexes (ZnPc) showed that complexes containing electron-donating groups have higher photostability. Germanium phthalocyanine complexes (GePc) undergo phototransformation rather than direct photobleaching and the tin phthalocyanine complexes (SnPc) undergo photobleaching mediated by photoreduction of the phthalocyanine ring. Singlet oxygen production showed increased in the following order: GePc>SnPc>ZnPc. Triplet lifetimes of the GePc (168-340μs) are very similar to that of the ZnPc (197 - 366μs), but the triplet lifetimes of the SnPc are ten fold shorter (10 - 32μs ). Triplet quantum yields are higher for the GePc (0.20 - 0.50) and SnPc (0.08 - 0.45) than for the ZnPc (0.02 - 0.25). Fluorescence lifetimes of GePc ( 4.0 - 5.1 ns) are significantly longer than that of ZnPc (1.9 - 3.0 ns) and SnPc (0.2 - 0.4 ns). Fluorescence quantum yields decrease in the following order: GePc(0.21-0.31)>ZnPc(0.02-0.21)>SnPc(0.02- 0.06). Ring-substituted cobalt phthalocyanine complexes of the form CoPc(R)4 (R= NH2, N02, C(CH3)3, S03H and COOH) are compared for their catalytic activities towards the oxidation of cysteine. The potential for the electrocatalytic oxidation of cysteine is closely related to the Com/Co11 couple of the CoPc(R)4 complexes in acidic media and to the Con/Co1 couple in basic media. The catalytic current and the oxidation potential for cysteine are dependent on the pH of the solution, the potential becoming less positive and the currents increasing with increase in pH.
- Full Text:
- Date Issued: 2002
Elucidation and manipulation of the Hydantoin-Hydrolysing Enzyme System of Agrobacterium tumefaciens RU-OR for the Biocatalytic production of D-amino acids
- Authors: Hartley, Carol Janet
- Date: 2002
- Subjects: Amino acids Agrobacterium tumefaciens
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3916 , http://hdl.handle.net/10962/d1003975
- Description: There is widespread interest in the biocatalytic production of enantiomerically pure D-amino acids for use in the synthesis of antibiotics, insecticides, herbicides, drug carriers and many other pharmaceuticals. Hydantoin-hydrolysing enzyme systems can be successfully utilised to stereoselectively convert racemic hydantoins into enantiomerically pure amino acid products. In fact, the use of microbial D-hydantoinase and D-stereoselective N-carbamoyl amino acid amidohydrolase activity to produce D-p-hydroxyphenylglycine from D,L-5-phydroxyphenylhydantoin has been described as one of the most successful biotechnological applications of enzyme technology developed to date. A need to utilise the novel biodiversity of South African microorganisms for the development of an indigenous process to produce enantiomerically pure amino acids was identified in 1995. Subsequently, the Rhodes Hydantoinase Group was established and several local hydantoin-hydrolysing microorganisms were isolated. The research in this study describes the isolation and selection of Agrobacterium tumefaciens RU-OR, which produced D-stereoselective hydantoinhydrolysing activity. Characterisation of the hydantoin-hydrolysing enzyme system of RU-OR revealed novel biocatalytic properties, and potential for the application of this strain for the biocatalytic production of D-amino acids. A fundamental understanding of the regulation of hydantoin-hydrolysing enzyme activity in A. tumefaciens RU-OR was established, and utilised to produce mutant strains with altered regulation of hydantoin-hydrolysing activity. These strains were used to further elucidate the mechanisms regulating the production of hydantoins-hydrolysing activity in A. tumefaciens RU-OR cells. Overproduction of hydantoinase and N-carbamoyl-D-amino acid amidohydrolase activity in selected mutant strains resulted in efficient conversion of D,L-5-p-hydroxyphenylhydantoin to D-p-hydroxyphenylglycine. Thus the establishment of a primary understanding of the hydantoin-hydrolysing enzyme system in A. tumefaciens RU-OR could be used to manipulate the hydantoin-hydrolysing activity in RU-OR cells to produce an improved biocatalyst. The isolation of A. tumfecaiens RU-OR genes encoding for hydantoin-hydrolysing activity revealed two separate N-carbamoyl-D-amino acid amidohydrolaseencoding genes (ncaR1 and ncaR2) in this bacterium with distinct chromosomal locations, nucleotide coding sequence and predicted primary amino acid sequence. The novel biocatalytic properties of the hydantoin-hydrolysing enzyme system in A. tumefaciens RU-OR and mutant derivatives present fascinating opportunities for further elucidation of the natural function, regulation and biocatalytic potential of hydantoin-hydrolysing enzymes.
- Full Text:
- Date Issued: 2002
- Authors: Hartley, Carol Janet
- Date: 2002
- Subjects: Amino acids Agrobacterium tumefaciens
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3916 , http://hdl.handle.net/10962/d1003975
- Description: There is widespread interest in the biocatalytic production of enantiomerically pure D-amino acids for use in the synthesis of antibiotics, insecticides, herbicides, drug carriers and many other pharmaceuticals. Hydantoin-hydrolysing enzyme systems can be successfully utilised to stereoselectively convert racemic hydantoins into enantiomerically pure amino acid products. In fact, the use of microbial D-hydantoinase and D-stereoselective N-carbamoyl amino acid amidohydrolase activity to produce D-p-hydroxyphenylglycine from D,L-5-phydroxyphenylhydantoin has been described as one of the most successful biotechnological applications of enzyme technology developed to date. A need to utilise the novel biodiversity of South African microorganisms for the development of an indigenous process to produce enantiomerically pure amino acids was identified in 1995. Subsequently, the Rhodes Hydantoinase Group was established and several local hydantoin-hydrolysing microorganisms were isolated. The research in this study describes the isolation and selection of Agrobacterium tumefaciens RU-OR, which produced D-stereoselective hydantoinhydrolysing activity. Characterisation of the hydantoin-hydrolysing enzyme system of RU-OR revealed novel biocatalytic properties, and potential for the application of this strain for the biocatalytic production of D-amino acids. A fundamental understanding of the regulation of hydantoin-hydrolysing enzyme activity in A. tumefaciens RU-OR was established, and utilised to produce mutant strains with altered regulation of hydantoin-hydrolysing activity. These strains were used to further elucidate the mechanisms regulating the production of hydantoins-hydrolysing activity in A. tumefaciens RU-OR cells. Overproduction of hydantoinase and N-carbamoyl-D-amino acid amidohydrolase activity in selected mutant strains resulted in efficient conversion of D,L-5-p-hydroxyphenylhydantoin to D-p-hydroxyphenylglycine. Thus the establishment of a primary understanding of the hydantoin-hydrolysing enzyme system in A. tumefaciens RU-OR could be used to manipulate the hydantoin-hydrolysing activity in RU-OR cells to produce an improved biocatalyst. The isolation of A. tumfecaiens RU-OR genes encoding for hydantoin-hydrolysing activity revealed two separate N-carbamoyl-D-amino acid amidohydrolaseencoding genes (ncaR1 and ncaR2) in this bacterium with distinct chromosomal locations, nucleotide coding sequence and predicted primary amino acid sequence. The novel biocatalytic properties of the hydantoin-hydrolysing enzyme system in A. tumefaciens RU-OR and mutant derivatives present fascinating opportunities for further elucidation of the natural function, regulation and biocatalytic potential of hydantoin-hydrolysing enzymes.
- Full Text:
- Date Issued: 2002
Employee ownership in the context of globalisation: a developing country perspective
- NALEDI
- Authors: NALEDI
- Date: 2002
- Subjects: NALEDI
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/153882 , vital:39532
- Description: This paper represents an initial set of ideas focused on employee ownership within the developing country context. The central question being explored is ‘To what extent can employee ownership support the broader goal of poverty reduction in South Africa (and, by extension, in the developing country context)?’. This is a rather broad question, and as such this note sets out to begin the discussion on this question, rather than seek to provide a definite set of answers. The critical perspectives put forward in this note draw heavily on experiences and debates in South Africa, and particularly those within the labour movement.
- Full Text:
- Date Issued: 2002
- Authors: NALEDI
- Date: 2002
- Subjects: NALEDI
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/153882 , vital:39532
- Description: This paper represents an initial set of ideas focused on employee ownership within the developing country context. The central question being explored is ‘To what extent can employee ownership support the broader goal of poverty reduction in South Africa (and, by extension, in the developing country context)?’. This is a rather broad question, and as such this note sets out to begin the discussion on this question, rather than seek to provide a definite set of answers. The critical perspectives put forward in this note draw heavily on experiences and debates in South Africa, and particularly those within the labour movement.
- Full Text:
- Date Issued: 2002
English in the prison services: a case of breaking the law?
- De Klerk, Vivian A, Barkhuizen, Gary
- Authors: De Klerk, Vivian A , Barkhuizen, Gary
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6133 , http://hdl.handle.net/10962/d1011585
- Description: In this paper we report on an investigation into the use of English in a prison in the Eastern Cape Province, run by the Department of Correctional Services (CS) five years after the declaration of an official multilingual policy. The investigation consisted of a range of interviews and observations in this institution, aimed at establishing the extent to which the national language policy is actually being implemented on the ground. Findings suggest that the use of English predominates in the high, official domains, that there is a marked avoidance of Afrikaans, and that Xhosa, the main language of the Eastern Cape Province, increasingly occupies the lower, unofficial domains. Tensions between policy and practice are discussed, and it is argued that the CS has shown that pragmatism is a much stronger force than ideology. While the roles of Xhosa and Afrikaans appear to be in the process of reversing in the Grahamstown prison, English has emerged as stronger there than it has ever been before. And because it will continue to be a necessary prerequisite for the mobility and promotion of staff in the country as a whole, and the lingua franca for an increasingly mobile criminal population (which means the prisons are likely to become increasingly linguistically diverse, rather than settling into regional patterns), everyone will have to have some proficiency in English, which, ironically, will promote and strengthen it even more.
- Full Text:
- Date Issued: 2002
- Authors: De Klerk, Vivian A , Barkhuizen, Gary
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6133 , http://hdl.handle.net/10962/d1011585
- Description: In this paper we report on an investigation into the use of English in a prison in the Eastern Cape Province, run by the Department of Correctional Services (CS) five years after the declaration of an official multilingual policy. The investigation consisted of a range of interviews and observations in this institution, aimed at establishing the extent to which the national language policy is actually being implemented on the ground. Findings suggest that the use of English predominates in the high, official domains, that there is a marked avoidance of Afrikaans, and that Xhosa, the main language of the Eastern Cape Province, increasingly occupies the lower, unofficial domains. Tensions between policy and practice are discussed, and it is argued that the CS has shown that pragmatism is a much stronger force than ideology. While the roles of Xhosa and Afrikaans appear to be in the process of reversing in the Grahamstown prison, English has emerged as stronger there than it has ever been before. And because it will continue to be a necessary prerequisite for the mobility and promotion of staff in the country as a whole, and the lingua franca for an increasingly mobile criminal population (which means the prisons are likely to become increasingly linguistically diverse, rather than settling into regional patterns), everyone will have to have some proficiency in English, which, ironically, will promote and strengthen it even more.
- Full Text:
- Date Issued: 2002
Evaluation of broiler performance under small-scale and semi-commercial farming conditions in the Northern Province
- Authors: Nembilwi, Daniel
- Date: 2002
- Subjects: Broilers (Chickens)
- Language: English
- Type: Thesis , Masters , MTech (Agricultural Management)
- Identifier: vital:10964 , http://hdl.handle.net/10948/92 , Broilers (Chickens)
- Description: Introduction: In the Northern region of the Northern Province, there is an increase in the number of small-scale and semi-commercial farms in all sectors of agriculture. This includes the production of grains, vegetables, fruits and livestock. Broiler production seemed to be a much-preferred alternative of development in community based projects and emerging farmers have shown keen interest. This is because broiler production requires less space than ruminants and is ready for human consumption within a very short period of time. Poultry production provides a constant source of income and protein with a big customer demand. By the year 2000, broiler production is expected to reach 4000 million and 7.5 million tons of poultry feeds in the world. Many countries have initiated programs aimed at improving small-scale poultry as a means of helping to bring socio- economic benefits to rural communities (Panda, 1989). In order to feed the ever rising population of 4.9 million in the Northern Province (1996 Census), there must be an increase in the production of broilers as a primary source of top quality animal protein. With the high unemployment rate (46%) in the Northern Province, self- employment projects are needed which comply with agro- processing. More than 90 community projects based on poultry production in the Northern region of the Northern Province had been established in order to reduce the high rate of unemployment. Today more people have engaged themselves in community projects especially in poultry production than ever before. Some of the constrains of broiler production at both small-scale and semi-commercial farming condition includes inadequate ventilation system. Lack of suitable health care facilities and frequently the absence of efficient marketing structures form part of the obstacles to the rapid development of poultry production. Feed costs which remain the highest input cost in the production of broilers represent between 60 to 70% or more of the total costs of broiler productions (Benyi and Habi, 1998). Lack of management skills and training for small and semi-commercial farmers makes it difficult to obtain optimum performance. The objective of this study is to evaluate the performance of broilers as influenced by environmental factors under small.
- Full Text:
- Date Issued: 2002
- Authors: Nembilwi, Daniel
- Date: 2002
- Subjects: Broilers (Chickens)
- Language: English
- Type: Thesis , Masters , MTech (Agricultural Management)
- Identifier: vital:10964 , http://hdl.handle.net/10948/92 , Broilers (Chickens)
- Description: Introduction: In the Northern region of the Northern Province, there is an increase in the number of small-scale and semi-commercial farms in all sectors of agriculture. This includes the production of grains, vegetables, fruits and livestock. Broiler production seemed to be a much-preferred alternative of development in community based projects and emerging farmers have shown keen interest. This is because broiler production requires less space than ruminants and is ready for human consumption within a very short period of time. Poultry production provides a constant source of income and protein with a big customer demand. By the year 2000, broiler production is expected to reach 4000 million and 7.5 million tons of poultry feeds in the world. Many countries have initiated programs aimed at improving small-scale poultry as a means of helping to bring socio- economic benefits to rural communities (Panda, 1989). In order to feed the ever rising population of 4.9 million in the Northern Province (1996 Census), there must be an increase in the production of broilers as a primary source of top quality animal protein. With the high unemployment rate (46%) in the Northern Province, self- employment projects are needed which comply with agro- processing. More than 90 community projects based on poultry production in the Northern region of the Northern Province had been established in order to reduce the high rate of unemployment. Today more people have engaged themselves in community projects especially in poultry production than ever before. Some of the constrains of broiler production at both small-scale and semi-commercial farming condition includes inadequate ventilation system. Lack of suitable health care facilities and frequently the absence of efficient marketing structures form part of the obstacles to the rapid development of poultry production. Feed costs which remain the highest input cost in the production of broilers represent between 60 to 70% or more of the total costs of broiler productions (Benyi and Habi, 1998). Lack of management skills and training for small and semi-commercial farmers makes it difficult to obtain optimum performance. The objective of this study is to evaluate the performance of broilers as influenced by environmental factors under small.
- Full Text:
- Date Issued: 2002
Evaluation of manufacturing processes for the production of atrazine
- Authors: Schaefer, Melissa Claire
- Date: 2002
- Subjects: Atrazine , Pesticides
- Language: English
- Type: Thesis , Masters , MTech (Chemistry)
- Identifier: vital:10960 , http://hdl.handle.net/10948/96 , Atrazine , Pesticides
- Description: This report describes the results of investigations carried out with the view to find an alternative for MIBK as solvent for the production of atrazine as currently practised by Dow AgroSciences in South Africa. The main motivating factors for the said investigation was: · to increase the yield of atrazine produced, · to reduce the amount of organics, consisting essentially of reaction solvent containing dissolved product, in the aqueous process effluent, and · to improve the properties of the solid (crystalline) product to enable easier product formulation. Synthetic reactions carried out in the absence of organic solvent, i.e. in essentially a 10% NaCl solution containing a surfactant, proved rather disappointing. Low yields of atrazine were obtained together with relatively large amounts of by-products such as propazine and simazine, irrespective of the nature of the surfactant. The reason for the low yield of atrazine and high yields of by-products were established in competing substitution reactions. In these reactions, IPA was reacted with an equimolar mixture of cyanuric chloride and mono-i (first reaction intermediate) in both aqueous medium and in toluene as reaction solvent. The results of these experiments indicated that in aqueous medium IPA reacts faster with mono-i than cyanuric chloride to give propazine as by-product. In toluene, however, the preferred reaction is with cyanuric chloride to give more mono-i as product. Toluene was investigated as an alternative organic solvent to MIBK in view of its desirable properties such as low solubility in water and ease of recovery and recycling. The synthesis of atrazine was optimised in terms of addition sequence and rates of amine reagents and base (HCl acceptor), both by means of benchscale reactions and reaction calorimetry. Reaction energy profiles indicated that both the reaction of secondary amine/NaOH and primary amine/NaOH were virtually instantaneous. This implies that the reaction can be performed under feed control conditions. Of particular importance in ensuring high yields of high purity product was accurate temperature control (since both reaction steps are highly exothermic) and mixing. The latter was important in view of the rapid reaction of amine/NaOH with cyanuric chloride, as well as the possible reaction of mono-i, the first reaction intermediate, with IPA in cases of local excesses of reagent. Under optimum conditions, a yield of atrazine > 97% could be achieved where the resultant product was well within stipulated product specifications. In view of the results obtained, the following recommendations regarding the synthesis of atrazine in toluene as reaction solvent can be made: · Use a reagent addition sequence that staggers the addition of amine and NaOH in such a manner that amine is added first for a short while, followed by the simultaneous addition of amine and NaOH, and ending with NaOH. Use two reaction vessels in series, one for the IPA addition reaction and one for the MEA addition reaction. In this manner the reaction can be run on a continuous basis since no lag time between amine additions is required. Also, smaller reactors may be used whilst maintaining high production rates. Smaller reactors will improve both temperature control and mixing of reagents.
- Full Text:
- Date Issued: 2002
- Authors: Schaefer, Melissa Claire
- Date: 2002
- Subjects: Atrazine , Pesticides
- Language: English
- Type: Thesis , Masters , MTech (Chemistry)
- Identifier: vital:10960 , http://hdl.handle.net/10948/96 , Atrazine , Pesticides
- Description: This report describes the results of investigations carried out with the view to find an alternative for MIBK as solvent for the production of atrazine as currently practised by Dow AgroSciences in South Africa. The main motivating factors for the said investigation was: · to increase the yield of atrazine produced, · to reduce the amount of organics, consisting essentially of reaction solvent containing dissolved product, in the aqueous process effluent, and · to improve the properties of the solid (crystalline) product to enable easier product formulation. Synthetic reactions carried out in the absence of organic solvent, i.e. in essentially a 10% NaCl solution containing a surfactant, proved rather disappointing. Low yields of atrazine were obtained together with relatively large amounts of by-products such as propazine and simazine, irrespective of the nature of the surfactant. The reason for the low yield of atrazine and high yields of by-products were established in competing substitution reactions. In these reactions, IPA was reacted with an equimolar mixture of cyanuric chloride and mono-i (first reaction intermediate) in both aqueous medium and in toluene as reaction solvent. The results of these experiments indicated that in aqueous medium IPA reacts faster with mono-i than cyanuric chloride to give propazine as by-product. In toluene, however, the preferred reaction is with cyanuric chloride to give more mono-i as product. Toluene was investigated as an alternative organic solvent to MIBK in view of its desirable properties such as low solubility in water and ease of recovery and recycling. The synthesis of atrazine was optimised in terms of addition sequence and rates of amine reagents and base (HCl acceptor), both by means of benchscale reactions and reaction calorimetry. Reaction energy profiles indicated that both the reaction of secondary amine/NaOH and primary amine/NaOH were virtually instantaneous. This implies that the reaction can be performed under feed control conditions. Of particular importance in ensuring high yields of high purity product was accurate temperature control (since both reaction steps are highly exothermic) and mixing. The latter was important in view of the rapid reaction of amine/NaOH with cyanuric chloride, as well as the possible reaction of mono-i, the first reaction intermediate, with IPA in cases of local excesses of reagent. Under optimum conditions, a yield of atrazine > 97% could be achieved where the resultant product was well within stipulated product specifications. In view of the results obtained, the following recommendations regarding the synthesis of atrazine in toluene as reaction solvent can be made: · Use a reagent addition sequence that staggers the addition of amine and NaOH in such a manner that amine is added first for a short while, followed by the simultaneous addition of amine and NaOH, and ending with NaOH. Use two reaction vessels in series, one for the IPA addition reaction and one for the MEA addition reaction. In this manner the reaction can be run on a continuous basis since no lag time between amine additions is required. Also, smaller reactors may be used whilst maintaining high production rates. Smaller reactors will improve both temperature control and mixing of reagents.
- Full Text:
- Date Issued: 2002
Exploring the perceived value of work as part of psychosocial rehabilitation of the state patient : Komani Hospital, Queenstown
- Authors: Crocker, Ann Petro
- Date: 2002
- Subjects: Work -- Psychological aspects Mentally ill -- Attitudes
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:5953 , http://hdl.handle.net/10962/d1007464
- Description: During the research an attempt was made to gain an understanding of the perceived value of work in psychosocial rehabilitation with the Sate patient at Komani Hospital. The respondents' motivation to work and what they gain from working, was investigated, as well as the experience of the nonworking respondents and their motivation not to work. To achieve this, ten respondents who were working and ten respondents who were not working, were interviewed. This study involves only a limited number of State patients at Komani Hospital and therefore findings cannot be generalised and also because the study was done at one Hospital only. A literature study was undertaken during which it was evident that work as part of vocational rehabilitation contributed to the well being of the mentally disabled person. It was also stated in the literature that the disabled person must be actively involved in his/her own rehabilitation planning and that the person must make conscious decisions to move away from the "sick" role and participate in his/her rehabilitation process. Interview schedules were developed. Response received from the twenty participants was analysed. The overall findings of the study showed that the majority of respondents who were working, were motivated by money. The fact that the respondents work from Hospital and therefore disrupt the Hospital routine, work with abled co-workers and feeling needed by the factory where they are employed. also emphasised the respondents' motivation to keep on working. The findings of the study with the non-working group showed that some respondents want to work, but there are not enough work opportunities available in and from Hospital. The non-working respondents are not interested in working at the occupational therapy department because the pay patients get for work done at the department is too little, and therefore they reject the work there. Some respondents do not want to work. whether work is available or not. The non-working group is largely dependent on staff and co-patients for an income, or tobacco. The predominant activity of the non-working group of respondents during the day, as well as that of the majority of the working group respondents during weekends was sleeping, talking to friends, and smoking. The research findings, conclusions and recommendations could contribute to a better understanding of patients and the value of work for the patient in a Psychiatric Hospital.
- Full Text:
- Date Issued: 2002
- Authors: Crocker, Ann Petro
- Date: 2002
- Subjects: Work -- Psychological aspects Mentally ill -- Attitudes
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:5953 , http://hdl.handle.net/10962/d1007464
- Description: During the research an attempt was made to gain an understanding of the perceived value of work in psychosocial rehabilitation with the Sate patient at Komani Hospital. The respondents' motivation to work and what they gain from working, was investigated, as well as the experience of the nonworking respondents and their motivation not to work. To achieve this, ten respondents who were working and ten respondents who were not working, were interviewed. This study involves only a limited number of State patients at Komani Hospital and therefore findings cannot be generalised and also because the study was done at one Hospital only. A literature study was undertaken during which it was evident that work as part of vocational rehabilitation contributed to the well being of the mentally disabled person. It was also stated in the literature that the disabled person must be actively involved in his/her own rehabilitation planning and that the person must make conscious decisions to move away from the "sick" role and participate in his/her rehabilitation process. Interview schedules were developed. Response received from the twenty participants was analysed. The overall findings of the study showed that the majority of respondents who were working, were motivated by money. The fact that the respondents work from Hospital and therefore disrupt the Hospital routine, work with abled co-workers and feeling needed by the factory where they are employed. also emphasised the respondents' motivation to keep on working. The findings of the study with the non-working group showed that some respondents want to work, but there are not enough work opportunities available in and from Hospital. The non-working respondents are not interested in working at the occupational therapy department because the pay patients get for work done at the department is too little, and therefore they reject the work there. Some respondents do not want to work. whether work is available or not. The non-working group is largely dependent on staff and co-patients for an income, or tobacco. The predominant activity of the non-working group of respondents during the day, as well as that of the majority of the working group respondents during weekends was sleeping, talking to friends, and smoking. The research findings, conclusions and recommendations could contribute to a better understanding of patients and the value of work for the patient in a Psychiatric Hospital.
- Full Text:
- Date Issued: 2002
Exploring the suitability of the evaluation criteria used in the MPT projects, by looking at hard and soft components of development programmes
- Authors: Ncapai, Wandile
- Date: 2002
- Subjects: Community development -- South Africa -- Eastern Cape , Community development , Economic development -- South Africa -- Eastern Cape , Economic development projects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3397 , http://hdl.handle.net/10962/d1018255
- Description: The study explores the suitability of the evaluation criteria used in Microprojects Programme Trust (MPT), by looking at hard and soft components of the development programme. In this sense hard components of development refer to those components of projects that are tangible and can be physically observed and can bring material changes to the life of the community. Soft components of development refer to those components of projects that bring qualitative transformation to the life of the community, i.e. increased levels of awareness, human well-being and the empowerment process that addresses the community's abstract needs, these are not tangible and often cannot be physically observed. Midway through its contract periods MPT evaluate all projects. The purpose of these mid term evaluations is to make recommendations to MPT on future approaches and methodology for community development and operations. The mid-term evaluation also influences the distribution and allocation of resources and funding. It was therefore vital that the criteria used are subject to tests and critical analysis so as to assess their validity. The assessment of the mid-term evaluation criteria used in MPT projects has been to further determine the appropriateness or suitability of the evaluation criteria as an instrument to measure and guide the MPT community development approach in the Eastern Cape. The method used was to conduct focus group discussions so as to get an insight into the local community situation as well as to assess non-tangible improvements and changes that have occurred in the life of the community as a result of the project. The information generated was used to compare what the community believe they achieved with what the official mid-term evaluation reports indicate was assessed and achieved and that was contrasted with what the literature recommends should have been assessed. The study found that the mid-term evaluations conducted on MPT projects have no social context in which the evaluations themselves were conducted. The terms of reference and criteria were based on the programme design which was formulated and compiled by the European Union without the participation of the local South African community. The findings also indicated that projects become unsuccessful or partly successful if the "soft" components which have a bearing on social and economic realities are neglected. The thesis ends with recommendations on how the mid-term evaluations as well as MPT programme can be developed to be more responsive to the needs as identified by the communities themselves. It is strongly believed that this study will provide a valuable contribution towards increasing the ability of MPT programme to bring about both material and qualitative transformation to the I ives of the disadvantaged community of the Eastern Cape whilst ensuring that the mid-term evaluations are developed and shaped to become an appropriate instrument to measure and guide MPT programme approach to community development.
- Full Text:
- Date Issued: 2002
- Authors: Ncapai, Wandile
- Date: 2002
- Subjects: Community development -- South Africa -- Eastern Cape , Community development , Economic development -- South Africa -- Eastern Cape , Economic development projects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3397 , http://hdl.handle.net/10962/d1018255
- Description: The study explores the suitability of the evaluation criteria used in Microprojects Programme Trust (MPT), by looking at hard and soft components of the development programme. In this sense hard components of development refer to those components of projects that are tangible and can be physically observed and can bring material changes to the life of the community. Soft components of development refer to those components of projects that bring qualitative transformation to the life of the community, i.e. increased levels of awareness, human well-being and the empowerment process that addresses the community's abstract needs, these are not tangible and often cannot be physically observed. Midway through its contract periods MPT evaluate all projects. The purpose of these mid term evaluations is to make recommendations to MPT on future approaches and methodology for community development and operations. The mid-term evaluation also influences the distribution and allocation of resources and funding. It was therefore vital that the criteria used are subject to tests and critical analysis so as to assess their validity. The assessment of the mid-term evaluation criteria used in MPT projects has been to further determine the appropriateness or suitability of the evaluation criteria as an instrument to measure and guide the MPT community development approach in the Eastern Cape. The method used was to conduct focus group discussions so as to get an insight into the local community situation as well as to assess non-tangible improvements and changes that have occurred in the life of the community as a result of the project. The information generated was used to compare what the community believe they achieved with what the official mid-term evaluation reports indicate was assessed and achieved and that was contrasted with what the literature recommends should have been assessed. The study found that the mid-term evaluations conducted on MPT projects have no social context in which the evaluations themselves were conducted. The terms of reference and criteria were based on the programme design which was formulated and compiled by the European Union without the participation of the local South African community. The findings also indicated that projects become unsuccessful or partly successful if the "soft" components which have a bearing on social and economic realities are neglected. The thesis ends with recommendations on how the mid-term evaluations as well as MPT programme can be developed to be more responsive to the needs as identified by the communities themselves. It is strongly believed that this study will provide a valuable contribution towards increasing the ability of MPT programme to bring about both material and qualitative transformation to the I ives of the disadvantaged community of the Eastern Cape whilst ensuring that the mid-term evaluations are developed and shaped to become an appropriate instrument to measure and guide MPT programme approach to community development.
- Full Text:
- Date Issued: 2002
Extension theorems on L-topological spaces and L-fuzzy vector spaces
- Authors: Pinchuck, Andrew
- Date: 2002
- Subjects: Topology , Vector spaces , Generalized spaces
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5405 , http://hdl.handle.net/10962/d1005219 , Topology , Vector spaces , Generalized spaces
- Description: A non-trivial example of an L-topological space, the fuzzy real line is examined. Various L-topological properties and their relationships are developed. Extension theorems on the L-fuzzy real line as well as extension theorems on more general L-topological spaces follow. Finally, a theory of L-fuzzy vector spaces leads up to a fuzzy version of the Hahn-Banach theorem.
- Full Text:
- Date Issued: 2002
- Authors: Pinchuck, Andrew
- Date: 2002
- Subjects: Topology , Vector spaces , Generalized spaces
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5405 , http://hdl.handle.net/10962/d1005219 , Topology , Vector spaces , Generalized spaces
- Description: A non-trivial example of an L-topological space, the fuzzy real line is examined. Various L-topological properties and their relationships are developed. Extension theorems on the L-fuzzy real line as well as extension theorems on more general L-topological spaces follow. Finally, a theory of L-fuzzy vector spaces leads up to a fuzzy version of the Hahn-Banach theorem.
- Full Text:
- Date Issued: 2002
Finite element simulations of shear aggregation as a mechanism to form platinum group elements (PGEs) in dyke-like ore bodies
- Authors: Mbandezi, Mxolisi Louis
- Date: 2002
- Subjects: Platinum group , Magmas , Shear flow , Geophysics , Terrestrial heat flow
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5561 , http://hdl.handle.net/10962/d1018249
- Description: This research describes a two-dimensional modelling effort of heat and mass transport in simplified intrusive models of sills and their feeder dykes. These simplified models resembled a complex intrusive system such as the Great Dyke of Zimbabwe. This study investigated the impact of variable geometry to transport processes in two ways. First the time evolution of heat and mass transport during cooling was investigated. Then emphasis was placed on the application of convective scavenging as a mechanism that leads to the formation of minerals of economic interest, in particular the Platinum Group Elements (PGEs). The Navier-Stokes equations employed generated regions of high shear within the magma where we expected enhanced collisions between the immiscible sulphide liquid particles and PGEs. These collisions scavenge PGEs from the primary melt, aggregate and concentrate it to form PGEs enrichment in zero shear zones. The PGEs scavenge; concentrate and 'glue' in zero shear zones in the early history of convection because of viscosity and dispersive pressure (Bagnold effect). The effect of increasing the geometry size enhances scavenging, creates bigger zero shear zones with dilute concentrate of PGEs but you get high shear near the roots of the dyke/sill where the concentration will not be dilute. The time evolution calculations show that increasing the size of the magma chamber results in stronger initial convection currents for large magma models than for small ones. However, convection takes, approximately the same time to cease for both models. The research concludes that the time evolution for convective heat transfer is dependent on the viscosity rather than on geometry size. However, conductive heat transfer to the e-folding temperature was almost six times as long for the large model (M4) than the small one (M2). Variable viscosity as a physical property was applied to models 2 and 4 only. Video animations that simulate the cooling process for these models are enclosed in a CD at the back of this thesis. These simulations provide information with regard to the emplacement history and distribution of PGEs ore bodies. This will assist the reserve estimation and the location of economic minerals.
- Full Text:
- Date Issued: 2002
- Authors: Mbandezi, Mxolisi Louis
- Date: 2002
- Subjects: Platinum group , Magmas , Shear flow , Geophysics , Terrestrial heat flow
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5561 , http://hdl.handle.net/10962/d1018249
- Description: This research describes a two-dimensional modelling effort of heat and mass transport in simplified intrusive models of sills and their feeder dykes. These simplified models resembled a complex intrusive system such as the Great Dyke of Zimbabwe. This study investigated the impact of variable geometry to transport processes in two ways. First the time evolution of heat and mass transport during cooling was investigated. Then emphasis was placed on the application of convective scavenging as a mechanism that leads to the formation of minerals of economic interest, in particular the Platinum Group Elements (PGEs). The Navier-Stokes equations employed generated regions of high shear within the magma where we expected enhanced collisions between the immiscible sulphide liquid particles and PGEs. These collisions scavenge PGEs from the primary melt, aggregate and concentrate it to form PGEs enrichment in zero shear zones. The PGEs scavenge; concentrate and 'glue' in zero shear zones in the early history of convection because of viscosity and dispersive pressure (Bagnold effect). The effect of increasing the geometry size enhances scavenging, creates bigger zero shear zones with dilute concentrate of PGEs but you get high shear near the roots of the dyke/sill where the concentration will not be dilute. The time evolution calculations show that increasing the size of the magma chamber results in stronger initial convection currents for large magma models than for small ones. However, convection takes, approximately the same time to cease for both models. The research concludes that the time evolution for convective heat transfer is dependent on the viscosity rather than on geometry size. However, conductive heat transfer to the e-folding temperature was almost six times as long for the large model (M4) than the small one (M2). Variable viscosity as a physical property was applied to models 2 and 4 only. Video animations that simulate the cooling process for these models are enclosed in a CD at the back of this thesis. These simulations provide information with regard to the emplacement history and distribution of PGEs ore bodies. This will assist the reserve estimation and the location of economic minerals.
- Full Text:
- Date Issued: 2002
Formulation and assessment of monolithic beta blocker sustained release tablets prepared by direct compression
- Authors: Kieser, Leith Faye
- Date: 2002
- Subjects: Drugs -- Dosage forms , Drugs -- Administration , Pharmacology, Experimental , Adrenergic beta blockers , Tablets (Medicine) , Tableting , Neuropharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3764 , http://hdl.handle.net/10962/d1003242 , Drugs -- Dosage forms , Drugs -- Administration , Pharmacology, Experimental , Adrenergic beta blockers , Tablets (Medicine) , Tableting , Neuropharmacology
- Description: Beta blockers are commonly prescribed for the chronic treatment of hypertension, one of the most prolific disease states worldwide. The beta blockers selected for this study include acebutolol hydrochloride, labetalol hydrochloride, metoprolol tartrate oxprenolol hydrochloride and propranolol hydrochloride. All of these compounds have a short elimination half-life, necessitating multiple dose per day regimens and therefore the development of sustained release dosage forms incorporating these agents was considered beneficial in terms of extending the dosing interval, with the aim of improving patient compliance and subsequent therapeutic outcomes. Preformulation studies that were conducted included moisture content analysis by Karl Fischer titration, and DSC, a method used to predict potential interactions between the drugs and tablet excipients. Tablets were manufactured by both wet granulation and direct compression techniques, and the resultant drug release characteristics were evaluated using the USP Apparatus 3(BIO.DIS). A validated isocratic HPLC method, capable of separating the five drug candidates simultaneously, was developed and used for the analysis of drug samples. Tablet quality was assessed using analyses that included the physical assessment of weight, diameter, thickness, hardness and friability, as well as content uniformity of tablets, before and after dissolution testing. Direct compression tablet formulations containing each of the five beta blockers were successfully adapted from a prototype wet granulation matrix tablet containing metoprolol tartrate, and various formulation variables were investigated to establish,their effect on the rate and extent of drug release from these tablets. The grade and quantity of ethylcellulose used in the wet granulation and direct compression formulae influenced the release rate of some drug candidates. In addition, an alternative formulation method, involving freeze-drying of the drug with an ethylcellulose dispersion, was shown to have potential for altering release rates further. Anti-frictional agents, talc and colloidal silicon dioxide, did not affect drug release from these matrices,however, they affected the physical character:istics such as tablet weight and thickness, of the resultant tablets. All of the matrix tablets formulated were shown to release drug according to square root of time kinetics, in a sustained manner over a 22 hour period.
- Full Text:
- Date Issued: 2002
- Authors: Kieser, Leith Faye
- Date: 2002
- Subjects: Drugs -- Dosage forms , Drugs -- Administration , Pharmacology, Experimental , Adrenergic beta blockers , Tablets (Medicine) , Tableting , Neuropharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3764 , http://hdl.handle.net/10962/d1003242 , Drugs -- Dosage forms , Drugs -- Administration , Pharmacology, Experimental , Adrenergic beta blockers , Tablets (Medicine) , Tableting , Neuropharmacology
- Description: Beta blockers are commonly prescribed for the chronic treatment of hypertension, one of the most prolific disease states worldwide. The beta blockers selected for this study include acebutolol hydrochloride, labetalol hydrochloride, metoprolol tartrate oxprenolol hydrochloride and propranolol hydrochloride. All of these compounds have a short elimination half-life, necessitating multiple dose per day regimens and therefore the development of sustained release dosage forms incorporating these agents was considered beneficial in terms of extending the dosing interval, with the aim of improving patient compliance and subsequent therapeutic outcomes. Preformulation studies that were conducted included moisture content analysis by Karl Fischer titration, and DSC, a method used to predict potential interactions between the drugs and tablet excipients. Tablets were manufactured by both wet granulation and direct compression techniques, and the resultant drug release characteristics were evaluated using the USP Apparatus 3(BIO.DIS). A validated isocratic HPLC method, capable of separating the five drug candidates simultaneously, was developed and used for the analysis of drug samples. Tablet quality was assessed using analyses that included the physical assessment of weight, diameter, thickness, hardness and friability, as well as content uniformity of tablets, before and after dissolution testing. Direct compression tablet formulations containing each of the five beta blockers were successfully adapted from a prototype wet granulation matrix tablet containing metoprolol tartrate, and various formulation variables were investigated to establish,their effect on the rate and extent of drug release from these tablets. The grade and quantity of ethylcellulose used in the wet granulation and direct compression formulae influenced the release rate of some drug candidates. In addition, an alternative formulation method, involving freeze-drying of the drug with an ethylcellulose dispersion, was shown to have potential for altering release rates further. Anti-frictional agents, talc and colloidal silicon dioxide, did not affect drug release from these matrices,however, they affected the physical character:istics such as tablet weight and thickness, of the resultant tablets. All of the matrix tablets formulated were shown to release drug according to square root of time kinetics, in a sustained manner over a 22 hour period.
- Full Text:
- Date Issued: 2002
Foucauldian feminism: the implications of governmentality
- Macleod, Catriona I, Durrheim, Kevin
- Authors: Macleod, Catriona I , Durrheim, Kevin
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6261 , http://hdl.handle.net/10962/d1007879
- Description: Foucauldian discourse has been received with varying degrees of enthusiasm within feminist circles. Some authors (e.g. Balbus, 1988; Di Leonardo, 1991; Hartsock, 1990) see a Foucauldian stance as incompatible with feminist theory, while others (e.g. Grimshaw, 1993; Hoy, 1988; McNay, 1992; Sawicki, 1988) advocate a positive relationship between Foucauldian discourse and feminism. And then there are those theorists (e.g. Burman, 1990) who stand between these two positions, stating that while Foucault offers useful insights and methods to feminists, it can also be dangerous.
- Full Text:
- Date Issued: 2002
- Authors: Macleod, Catriona I , Durrheim, Kevin
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6261 , http://hdl.handle.net/10962/d1007879
- Description: Foucauldian discourse has been received with varying degrees of enthusiasm within feminist circles. Some authors (e.g. Balbus, 1988; Di Leonardo, 1991; Hartsock, 1990) see a Foucauldian stance as incompatible with feminist theory, while others (e.g. Grimshaw, 1993; Hoy, 1988; McNay, 1992; Sawicki, 1988) advocate a positive relationship between Foucauldian discourse and feminism. And then there are those theorists (e.g. Burman, 1990) who stand between these two positions, stating that while Foucault offers useful insights and methods to feminists, it can also be dangerous.
- Full Text:
- Date Issued: 2002
From conflict to negotiation: nature-based development on the South African Wild Coast. Special edition
- Palmer, Robin C G, Timmermans, Herman G, Fay, Derek
- Authors: Palmer, Robin C G , Timmermans, Herman G , Fay, Derek
- Date: 2002
- Language: English
- Type: Text
- Identifier: vital:543 , http://hdl.handle.net/10962/d1011730
- Description: The Rio Earth Summit of 1992 introduced several new approaches to environmental management under the general heading of sustainable development. One of these approaches has forced conservationists to concede that it is no longer feasible or ethical to exlude resident communities from protected areas, as had been the practice for more than a century. The alternative approach highlighting considerations of social justice and economic empowerment, is to recognise that humans are also part of the local ecology, and to find sustainable ways to maintain local livelihoods along with biodiversity. Especially in the global South, resource-dependant communities associated with protected areas had long been subjected to removals or restrictions by the state, and had been forced to modify livelihoods historically dependant on abundant natural resources, usually resulting in their acute impoverishment. Eastern and Southern Africa had been particulr sites of the former protectionist policies and their frequently tragic sequels for communities. Following the Summit much energy has been expended on finding sustainable alternatives to relocation in these regions, particularly new livelihoods linked to ecotourism From Conflict to Negotiation provides a South African case study of the shift from protectionism to sustainable development in the 1990's. Located on the wild coast of the Eastern Cape, Dwesa-Cwebe consists of a nature and marine reserve with eight adjacent resident communities that have historically depended on local forest, grassland and coastal resources. This are has been the focus of one of the earliest efforts in the 'new' South Africa to restore to the Xhosa-speaking residents ownership of the protected area from which they had been excluded for decades. Unusually the resident initiated the process. While others celebrated the advent of the new democracy in South Africa in 1994, the residents of this remote area, whose grieviences had been ignored during the political transition, planned a protest strategy featuring co-ordinated invasions of the protected area. The protest action succeeded to the extent that it gained massive media attention and provoked the special attention of national and regional goverment, non-govermental organizations (NGOs) and academic researchers. An early academic intervention designed to bring the residents and conservationists together was later expanded. Complementing the roles of goverment and NGOs, environmentalists and socio-cultural anthropologists, among others involved in this project, have attempted to address the conundrum of sustainable development policy implementation in a complex setting. From conflict to Negotiation details the findings of this pioneering research project. It is the story of local empowerment regained as confrontation yielded to negotiation and negotiation yielded co-management, local ownership and developmental partnerships. This landmark study will provoke ongoing discussion and research in an exciting new forum of community development.
- Full Text:
- Date Issued: 2002
- Authors: Palmer, Robin C G , Timmermans, Herman G , Fay, Derek
- Date: 2002
- Language: English
- Type: Text
- Identifier: vital:543 , http://hdl.handle.net/10962/d1011730
- Description: The Rio Earth Summit of 1992 introduced several new approaches to environmental management under the general heading of sustainable development. One of these approaches has forced conservationists to concede that it is no longer feasible or ethical to exlude resident communities from protected areas, as had been the practice for more than a century. The alternative approach highlighting considerations of social justice and economic empowerment, is to recognise that humans are also part of the local ecology, and to find sustainable ways to maintain local livelihoods along with biodiversity. Especially in the global South, resource-dependant communities associated with protected areas had long been subjected to removals or restrictions by the state, and had been forced to modify livelihoods historically dependant on abundant natural resources, usually resulting in their acute impoverishment. Eastern and Southern Africa had been particulr sites of the former protectionist policies and their frequently tragic sequels for communities. Following the Summit much energy has been expended on finding sustainable alternatives to relocation in these regions, particularly new livelihoods linked to ecotourism From Conflict to Negotiation provides a South African case study of the shift from protectionism to sustainable development in the 1990's. Located on the wild coast of the Eastern Cape, Dwesa-Cwebe consists of a nature and marine reserve with eight adjacent resident communities that have historically depended on local forest, grassland and coastal resources. This are has been the focus of one of the earliest efforts in the 'new' South Africa to restore to the Xhosa-speaking residents ownership of the protected area from which they had been excluded for decades. Unusually the resident initiated the process. While others celebrated the advent of the new democracy in South Africa in 1994, the residents of this remote area, whose grieviences had been ignored during the political transition, planned a protest strategy featuring co-ordinated invasions of the protected area. The protest action succeeded to the extent that it gained massive media attention and provoked the special attention of national and regional goverment, non-govermental organizations (NGOs) and academic researchers. An early academic intervention designed to bring the residents and conservationists together was later expanded. Complementing the roles of goverment and NGOs, environmentalists and socio-cultural anthropologists, among others involved in this project, have attempted to address the conundrum of sustainable development policy implementation in a complex setting. From conflict to Negotiation details the findings of this pioneering research project. It is the story of local empowerment regained as confrontation yielded to negotiation and negotiation yielded co-management, local ownership and developmental partnerships. This landmark study will provoke ongoing discussion and research in an exciting new forum of community development.
- Full Text:
- Date Issued: 2002
Fuel wood use in South Africa: Where to in the 21st Century?
- Williams, Anthony, Shackleton, Charlie M
- Authors: Williams, Anthony , Shackleton, Charlie M
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183026 , vital:43905 , xlink:href="https://doi.org/10.1080/20702620.2002.10434611"
- Description: South Africa is well known for the dichotomous nature of its economy, with its juxtaposed first and third world characteristics, perhaps nowhere more starkly evident than in the energy sector. South Africa produces and consumes over 60% of the total electrical energy on the African continent, and is ranked twelfth in the world in terms of carbon emissions (EIA, 2002). Yet the majority of the South African population does not have access to electricity, and despite the enormous strides taken since 1994 to increase household access to electricity (NER, 2001), newly electrified households, more often than not, cannot afford the appliances nor the monthly costs required to significantly improve their quality of life (White et al., 1997). Thus, most rural and many peri-urban households continue to use fuelwood as their primary energy source (Griffin et al., 1992; Dyer, 1996; Kotze, 1996; Williams et al., 1996). Fuelwood use presents both opportunities and risks.
- Full Text:
- Date Issued: 2002
- Authors: Williams, Anthony , Shackleton, Charlie M
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183026 , vital:43905 , xlink:href="https://doi.org/10.1080/20702620.2002.10434611"
- Description: South Africa is well known for the dichotomous nature of its economy, with its juxtaposed first and third world characteristics, perhaps nowhere more starkly evident than in the energy sector. South Africa produces and consumes over 60% of the total electrical energy on the African continent, and is ranked twelfth in the world in terms of carbon emissions (EIA, 2002). Yet the majority of the South African population does not have access to electricity, and despite the enormous strides taken since 1994 to increase household access to electricity (NER, 2001), newly electrified households, more often than not, cannot afford the appliances nor the monthly costs required to significantly improve their quality of life (White et al., 1997). Thus, most rural and many peri-urban households continue to use fuelwood as their primary energy source (Griffin et al., 1992; Dyer, 1996; Kotze, 1996; Williams et al., 1996). Fuelwood use presents both opportunities and risks.
- Full Text:
- Date Issued: 2002
Gender discourse and Malawian rural communities: a study of the meaning the people of traditional authority Likoswe of Chiradzulo make from human rights and gender messages
- Authors: Manda, Levi Zeleza
- Date: 2002
- Subjects: Human rights -- Malawi , Mass media in community development -- Malawi , Communication in community development -- Malawi , Mass media -- Social aspects -- Malawi , Mass media criticism -- Malawi , Women's rights -- Malawi , Sex role -- Malawi
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3456 , http://hdl.handle.net/10962/d1002910 , Human rights -- Malawi , Mass media in community development -- Malawi , Communication in community development -- Malawi , Mass media -- Social aspects -- Malawi , Mass media criticism -- Malawi , Women's rights -- Malawi , Sex role -- Malawi
- Description: Contrary to earlier beliefs and media theories such as the hypodermic needle or magic bullet, the audience of public communication is not a passive homogenous mass that easily succumbs to media influence. The audience is active, that is, it makes an effort to interpret media content. Depending on predisposing cultural, political, religious, or economic factors the audience makes different meanings from media texts. Media messages are not wholly controlled by producers, although the producers have their preferred and expected readings. Using qualitative research techniques associated with ethnographic and cultural studies (notably focus group discussions), this study sought to explore the meanings rural people in Malawi make out of human rights and gender messages broadcast on radio and through music. Interpreted against Stuart Hall's (1974b) Encoding and Decoding model, the study concludes that while rural communities understand and appreciate the new sociopolitical discourse, they take a negotiated stance because they have their own doubts and fears. They fear losing their cultural identity. Additionally, men, in particular, negotiate the messages because they fear losing their social power over land, property and family.
- Full Text:
- Date Issued: 2002
- Authors: Manda, Levi Zeleza
- Date: 2002
- Subjects: Human rights -- Malawi , Mass media in community development -- Malawi , Communication in community development -- Malawi , Mass media -- Social aspects -- Malawi , Mass media criticism -- Malawi , Women's rights -- Malawi , Sex role -- Malawi
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3456 , http://hdl.handle.net/10962/d1002910 , Human rights -- Malawi , Mass media in community development -- Malawi , Communication in community development -- Malawi , Mass media -- Social aspects -- Malawi , Mass media criticism -- Malawi , Women's rights -- Malawi , Sex role -- Malawi
- Description: Contrary to earlier beliefs and media theories such as the hypodermic needle or magic bullet, the audience of public communication is not a passive homogenous mass that easily succumbs to media influence. The audience is active, that is, it makes an effort to interpret media content. Depending on predisposing cultural, political, religious, or economic factors the audience makes different meanings from media texts. Media messages are not wholly controlled by producers, although the producers have their preferred and expected readings. Using qualitative research techniques associated with ethnographic and cultural studies (notably focus group discussions), this study sought to explore the meanings rural people in Malawi make out of human rights and gender messages broadcast on radio and through music. Interpreted against Stuart Hall's (1974b) Encoding and Decoding model, the study concludes that while rural communities understand and appreciate the new sociopolitical discourse, they take a negotiated stance because they have their own doubts and fears. They fear losing their cultural identity. Additionally, men, in particular, negotiate the messages because they fear losing their social power over land, property and family.
- Full Text:
- Date Issued: 2002
Genetic characterization of conspecific populations of Tilapia Sparrmanii (A.Smith 1840) in the dolomitic sinkholes and springs of the North-West Province (South Africa), and their comparison to Tilapia Guinasana (Trewavas 1936)
- Authors: Nxomani, Clifford David
- Date: 2002
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4079 , http://hdl.handle.net/10962/d1007452
- Description: This study was undertaken to investigate the genetic relationships of allopatric populations of the cichlid fish, Tilapia sparrmanii (A. Smith 1840) inhabiting the sinkholes and springs of the North West Province, South Africa. It also examined the genetic relationships of T sparrmanii to its polychromatic sister species, Tilapia guinasana (Trewavas 1936) which is endemic to the Guinas sinkhole in Namibia. Finally, the study investigated whether there is a genetic basis for T guinasana's colour polymorphism. The research was prompted by the concern of conservation authorities about the possible loss of unique fauna given the high demand for use of the subterranean waters for agricultural, domestic and industrial purposes. Such demands have the potential to drain these habitats. Further concerns related to habitat destruction and the introduction of alien species in the ecosystems inhabited by both fish species. Three approaches were adopted in attempting to answer the above questions. First was the investigation of Sodium dodecylsulphate (SDS)-Polyacrylamide Gel Electrophoresis (PAGE) of total cellular proteins as a fast and relatively inexpensive indicator of genetic relatedness between the fish populations. Secondly, genetic differentiation between the T sparrmanii populations and its relationship to T guinasana were assayed using restriction endonuclease analysis of Polymerase Chain Reaction (PCR)-amplified regions of the cytochrome b gene and the d-Ioop of mitochondrial DNA, coupled with Temperature Gradient Gel Electrophoresis (TGGE) analysis of the same regions. The third approach involved the use of Random Amplified Polymorphic DNA (RAPD) fingerprinting of the populations ofT sparrmanii as an indicator of genetic differentiation between them. RAPD fingerprinting was further used to investigate the genetic relationships between T sparrmanii and T guinasana and to probe the genetic basis of the polychromatism of the latter. SDS-PAGE did not reveal any genetic differentiation between the T sparrmanii populations, nor could the analysis detect variation within them. It however clearly distinguished at a species level between T sparrmanii and T guinasana as well as between these and other fish species, thus indicating its possible utility as an indicator of genetic relatedness at a species level. Mitochondrial studies employing the Restriction Fragment Length Polymorphism (RFLP) of Polymerase Chain Reaction (PCR)-amplified cytochrome b (1.1 kb) and d-Ioop regions (0.9 kb) with six and five restriction enzymes respectively, failed to reveal genetic differences within and between the allopatric populations. TGGE of500 bp of the d-Ioop and 400 bp of the 12sRNA PCR-amplified fragments did not reveal any differences between the populations of T. sparrmanii, nor did the analysis reveal any differences between T. sparrmanii and T. guinasana. The lack of differentiation between the T. sparrmanii populations by these mitochondrial Dna analysis techniques, despite habitat fragmentation, indicated a recent origin of the populations from a common ancestral population. Failure to distinguish between T. sparrmanii and T. guinasana may be related to the sensitivity of the techniques utilized. RAPD fingerprinting analysis indicated that the populations are genetically differentiated from each other. Using a measure of coefficient of variation, the population with the highest variation was the Wondergat population (13.99%), followed by the Klerkskraal popUlation (8.29%), the Malmani and Marico Oog populations (each with 5.88%) and the least variation (4.95 and 4.83%) was with the Amalinda and Molopo Oog populations respectively. This high degree of intra population similarity points to the fact that this differentiation is still confined within the limits of con specificity. The genetic distances between all of the T. sparrmanii populations across all primers ranged from 0.09 to 0.234 and averaged 0.146, a value that falls in the upper end of conspecific population differentiation. Such results indicate populational sub-division below the species level. RAPD fingerprinting therefore proved more sensitive than protein or mitochondrial studies. The differentiation it detected between the populations is a reflection of their adaptation to local conditions of the unique ecosystems they inhabit. A comparison with a subset of primers between T. guinasana and T. sparrmanii confirmed the separate species status of the former from the latter. The mean genetic distance between the T. sparrmanii populations was 0.136, compared to that between T. sparrmanii and T. guinasana which was found to be 0.374. Statistical analysis of the difference between the mean genetic distances indicated significance with 95% confidence. The polychromatism of T guinasana was investigated to determine whether there were significant differences between its five colour morphs. RAPD fingerprinting indicated with 95% confidence that there were significant differences between the colour forms based on the genetic distances computed between them. These genetic differences appeared to correlate with the observed assortative mating between the colour forms of the species. The manifestation of the polychromatism at sexual maturity in T guinasana probably indicates that colouration plays an important role in the breeding process. The genetic uniqueness shown here between the populations of T sparrmanii and the colour forms of T guinasana indicate for protective measures to be put in place if the genetic resources of the isolated fish populations are to be preserved. These must be coupled with a thorough assessment of the temporal and spatial distribution of genetic variability of the populations as a guide to a long-term management strategy for the fish populations and the ecosystems they inhabit. This study therefore has shown that the allopatric populations of T sparrmanii in the sinkholes and springs of the North-West Province are genetically unique, as well as show that the colour forms of T guinasana are genetically distinct.
- Full Text:
- Date Issued: 2002
- Authors: Nxomani, Clifford David
- Date: 2002
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4079 , http://hdl.handle.net/10962/d1007452
- Description: This study was undertaken to investigate the genetic relationships of allopatric populations of the cichlid fish, Tilapia sparrmanii (A. Smith 1840) inhabiting the sinkholes and springs of the North West Province, South Africa. It also examined the genetic relationships of T sparrmanii to its polychromatic sister species, Tilapia guinasana (Trewavas 1936) which is endemic to the Guinas sinkhole in Namibia. Finally, the study investigated whether there is a genetic basis for T guinasana's colour polymorphism. The research was prompted by the concern of conservation authorities about the possible loss of unique fauna given the high demand for use of the subterranean waters for agricultural, domestic and industrial purposes. Such demands have the potential to drain these habitats. Further concerns related to habitat destruction and the introduction of alien species in the ecosystems inhabited by both fish species. Three approaches were adopted in attempting to answer the above questions. First was the investigation of Sodium dodecylsulphate (SDS)-Polyacrylamide Gel Electrophoresis (PAGE) of total cellular proteins as a fast and relatively inexpensive indicator of genetic relatedness between the fish populations. Secondly, genetic differentiation between the T sparrmanii populations and its relationship to T guinasana were assayed using restriction endonuclease analysis of Polymerase Chain Reaction (PCR)-amplified regions of the cytochrome b gene and the d-Ioop of mitochondrial DNA, coupled with Temperature Gradient Gel Electrophoresis (TGGE) analysis of the same regions. The third approach involved the use of Random Amplified Polymorphic DNA (RAPD) fingerprinting of the populations ofT sparrmanii as an indicator of genetic differentiation between them. RAPD fingerprinting was further used to investigate the genetic relationships between T sparrmanii and T guinasana and to probe the genetic basis of the polychromatism of the latter. SDS-PAGE did not reveal any genetic differentiation between the T sparrmanii populations, nor could the analysis detect variation within them. It however clearly distinguished at a species level between T sparrmanii and T guinasana as well as between these and other fish species, thus indicating its possible utility as an indicator of genetic relatedness at a species level. Mitochondrial studies employing the Restriction Fragment Length Polymorphism (RFLP) of Polymerase Chain Reaction (PCR)-amplified cytochrome b (1.1 kb) and d-Ioop regions (0.9 kb) with six and five restriction enzymes respectively, failed to reveal genetic differences within and between the allopatric populations. TGGE of500 bp of the d-Ioop and 400 bp of the 12sRNA PCR-amplified fragments did not reveal any differences between the populations of T. sparrmanii, nor did the analysis reveal any differences between T. sparrmanii and T. guinasana. The lack of differentiation between the T. sparrmanii populations by these mitochondrial Dna analysis techniques, despite habitat fragmentation, indicated a recent origin of the populations from a common ancestral population. Failure to distinguish between T. sparrmanii and T. guinasana may be related to the sensitivity of the techniques utilized. RAPD fingerprinting analysis indicated that the populations are genetically differentiated from each other. Using a measure of coefficient of variation, the population with the highest variation was the Wondergat population (13.99%), followed by the Klerkskraal popUlation (8.29%), the Malmani and Marico Oog populations (each with 5.88%) and the least variation (4.95 and 4.83%) was with the Amalinda and Molopo Oog populations respectively. This high degree of intra population similarity points to the fact that this differentiation is still confined within the limits of con specificity. The genetic distances between all of the T. sparrmanii populations across all primers ranged from 0.09 to 0.234 and averaged 0.146, a value that falls in the upper end of conspecific population differentiation. Such results indicate populational sub-division below the species level. RAPD fingerprinting therefore proved more sensitive than protein or mitochondrial studies. The differentiation it detected between the populations is a reflection of their adaptation to local conditions of the unique ecosystems they inhabit. A comparison with a subset of primers between T. guinasana and T. sparrmanii confirmed the separate species status of the former from the latter. The mean genetic distance between the T. sparrmanii populations was 0.136, compared to that between T. sparrmanii and T. guinasana which was found to be 0.374. Statistical analysis of the difference between the mean genetic distances indicated significance with 95% confidence. The polychromatism of T guinasana was investigated to determine whether there were significant differences between its five colour morphs. RAPD fingerprinting indicated with 95% confidence that there were significant differences between the colour forms based on the genetic distances computed between them. These genetic differences appeared to correlate with the observed assortative mating between the colour forms of the species. The manifestation of the polychromatism at sexual maturity in T guinasana probably indicates that colouration plays an important role in the breeding process. The genetic uniqueness shown here between the populations of T sparrmanii and the colour forms of T guinasana indicate for protective measures to be put in place if the genetic resources of the isolated fish populations are to be preserved. These must be coupled with a thorough assessment of the temporal and spatial distribution of genetic variability of the populations as a guide to a long-term management strategy for the fish populations and the ecosystems they inhabit. This study therefore has shown that the allopatric populations of T sparrmanii in the sinkholes and springs of the North-West Province are genetically unique, as well as show that the colour forms of T guinasana are genetically distinct.
- Full Text:
- Date Issued: 2002