The artificial recharge of urban stormwater runoff in the Atlantis coastal aquifer
- Authors: Wright, Alan
- Date: 1992
- Subjects: Atlantis water resource management scheme , Urban hydrology -- South Africa , Urban runoff -- South Africa , Storm sewers -- South Africa , Water resources development -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4817 , http://hdl.handle.net/10962/d1005491 , Atlantis water resource management scheme , Urban hydrology -- South Africa , Urban runoff -- South Africa , Storm sewers -- South Africa , Water resources development -- South Africa
- Description: The thesis covers the investigation of the storm water runoff and artificial recharge components of the Atlantis Water Resource Management Scheme in the Southwestern Cape. The objective of the study was to obtain an in-depth knowledge of the process of artificial recharge of urban storm water runoff, in order to identify the most efficient recharge management strategy for the Atlantis aquifer. To achieve the objective it was necessary to first study the existing knowledge on urban storm water hydrology and artificial recharge by spreading, and to create a conceptual model of what might be expected. The study area was then investigated to examine how closely the actual situation was reflected by the conceptual model, enabling recommendations to be made for the sound management of the system. The stormwater runoff component was found to differ from most urban hydrological studies as a result of its large baseflow component. The sandy nature of the catchment, small percentage area of effective impervious surface, and high groundwater table resulted in the baseflow constituting more than 40% of the total storm water runoff and accounting for over 60% of the pollution load. The "first flush" effect established as a major source of pollution in other studies, was found to be of minor significance in this study area. The overall stormwater quality (excluding the noxious industrial baseflow) was found acceptable for artificial recharge within the study area, although the baseflow from the industrial sub-catchments showed the potential for being a major source of pollution in the future. The treated wastewater used for artificial recharge prior to 1987 was found to be unacceptable for recharge purposes. The treated industrial effluent should under no circumstances be recharged up-gradient of the Witzand well field. The treated domestic effluent although of a poorer quality than the resident Witzand well field groundwater could be recharged in order to boost recharge volumes and form a buffer against further intrusion by the poor quality groundwater from the Brakkefontein area. This would however only be acceptable if strict water quality control is maintained and recharge does not take place west of the present basin. The recharge basin was found to be well situated with respect to influencing the Witzand wellfield and maintaining a groundwater buffer against poor quality groundwater flow from the northeast towards the central area of the wellfield. Unfortunately the surrounding low-lying topography and sandy retaining walls have resulted in return flow and raised groundwater-levels. The raised groundwater mound does not comply with the conceptual model and together with the sandy nature of the unsaturated zone resulted in less effective purification during infiltration. The practice of letting large portions of the basin floor dry-out during summer was shown to be beneficial and the periodic cleaning of the deeper portions of the basin essential. The artificially recharged water was found to have influenced the upper portion of the aquifer well beyond the West Coast Road. The study of groundwater quality being a good method for tracing artificially recharged water. The groundwater quality has improved as a result of artificial recharge since the removal of treated wastewater from the recharge basin. The groundwater was (ii) found to be very responsive to the slightest changes in recharge basin water quality or/and quantity. Management of the recharge basin therefore had to be very much of a compromise between qualitative and quantitative approaches. The present approach of recharging all the stormwater runoff throughout the year providing the most efficient compromise under the present conditions. The study revealed that the most efficient recharge management strategy would be the recharge of treated domestic sewage effluent in the present recharge basin and all residential storm water runoff plus industrial "storm flow" stormwater runoff in a new recharge basin located northwest of the present basin. Strict water quality control must be maintained on the water discharged into the basins and an annual wet/dry cycle implemented within the basins to boost infiltration. The entire system should continue being monitored to safe guard the groundwater resource from pollution and over exploitation.
- Full Text:
- Date Issued: 1992
- Authors: Wright, Alan
- Date: 1992
- Subjects: Atlantis water resource management scheme , Urban hydrology -- South Africa , Urban runoff -- South Africa , Storm sewers -- South Africa , Water resources development -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4817 , http://hdl.handle.net/10962/d1005491 , Atlantis water resource management scheme , Urban hydrology -- South Africa , Urban runoff -- South Africa , Storm sewers -- South Africa , Water resources development -- South Africa
- Description: The thesis covers the investigation of the storm water runoff and artificial recharge components of the Atlantis Water Resource Management Scheme in the Southwestern Cape. The objective of the study was to obtain an in-depth knowledge of the process of artificial recharge of urban storm water runoff, in order to identify the most efficient recharge management strategy for the Atlantis aquifer. To achieve the objective it was necessary to first study the existing knowledge on urban storm water hydrology and artificial recharge by spreading, and to create a conceptual model of what might be expected. The study area was then investigated to examine how closely the actual situation was reflected by the conceptual model, enabling recommendations to be made for the sound management of the system. The stormwater runoff component was found to differ from most urban hydrological studies as a result of its large baseflow component. The sandy nature of the catchment, small percentage area of effective impervious surface, and high groundwater table resulted in the baseflow constituting more than 40% of the total storm water runoff and accounting for over 60% of the pollution load. The "first flush" effect established as a major source of pollution in other studies, was found to be of minor significance in this study area. The overall stormwater quality (excluding the noxious industrial baseflow) was found acceptable for artificial recharge within the study area, although the baseflow from the industrial sub-catchments showed the potential for being a major source of pollution in the future. The treated wastewater used for artificial recharge prior to 1987 was found to be unacceptable for recharge purposes. The treated industrial effluent should under no circumstances be recharged up-gradient of the Witzand well field. The treated domestic effluent although of a poorer quality than the resident Witzand well field groundwater could be recharged in order to boost recharge volumes and form a buffer against further intrusion by the poor quality groundwater from the Brakkefontein area. This would however only be acceptable if strict water quality control is maintained and recharge does not take place west of the present basin. The recharge basin was found to be well situated with respect to influencing the Witzand wellfield and maintaining a groundwater buffer against poor quality groundwater flow from the northeast towards the central area of the wellfield. Unfortunately the surrounding low-lying topography and sandy retaining walls have resulted in return flow and raised groundwater-levels. The raised groundwater mound does not comply with the conceptual model and together with the sandy nature of the unsaturated zone resulted in less effective purification during infiltration. The practice of letting large portions of the basin floor dry-out during summer was shown to be beneficial and the periodic cleaning of the deeper portions of the basin essential. The artificially recharged water was found to have influenced the upper portion of the aquifer well beyond the West Coast Road. The study of groundwater quality being a good method for tracing artificially recharged water. The groundwater quality has improved as a result of artificial recharge since the removal of treated wastewater from the recharge basin. The groundwater was (ii) found to be very responsive to the slightest changes in recharge basin water quality or/and quantity. Management of the recharge basin therefore had to be very much of a compromise between qualitative and quantitative approaches. The present approach of recharging all the stormwater runoff throughout the year providing the most efficient compromise under the present conditions. The study revealed that the most efficient recharge management strategy would be the recharge of treated domestic sewage effluent in the present recharge basin and all residential storm water runoff plus industrial "storm flow" stormwater runoff in a new recharge basin located northwest of the present basin. Strict water quality control must be maintained on the water discharged into the basins and an annual wet/dry cycle implemented within the basins to boost infiltration. The entire system should continue being monitored to safe guard the groundwater resource from pollution and over exploitation.
- Full Text:
- Date Issued: 1992
A rhetorical analysis of 1 Timothy 2:9-15 with a special focus on the role of women in the church
- Authors: Williams, Allan Alexander
- Date: 1992
- Subjects: Bible -- Criticism, interpretation, etc. , Women in the Bible , Women in Christianity -- History -- Early church, ca. 30-600 , Women in Christianity , Sexism in religion
- Language: English
- Type: Thesis , Masters , MTh
- Identifier: vital:1299 , http://hdl.handle.net/10962/d1015721
- Description: This thesis investigates the role of women in the early church as portrayed in 1 Timothy 2:9-15 using the recently-developed method of Rhetorical Analysis. It makes use of a rhetorical approach largely based on the method proposed by Kennedy, supplemented by insights from scholars who have emphasised the argumentative element in rhetoric. This method illustrates how the role of women in the church is decisively determined by the argument in the letter as a whole. A brief survey of classical rhetoric is given. The typical structure of a rhetorical discourse is listed with its component sections. The validity of using rhetorical analysis as a means for interpreting New Testament texts is justified. Textual units are identified from the structure of the text. Rhetorical insights are used to explain how the identified units cohere within the overall structure of the letter and how they relate to one another and interact. The thesis is developed that the section on women and teaching can only be meaningfully investigated in the light of the text as a whole and of the motifs in the letter. The thesis has a special focus on 2:9-15. This section is analysed in more detail than the rest of the text with the exception of 1 Timothy 1. As exordium, the latter provides the introduction to the situation dealt with in the letter, introduces the case, and sets the tone for the rest of the letter. The persuasive power of rhetoric in any situation depends to a large extent on its use of common tradition. The socio-cultural setting of the author is consequently analysed. Finally, the role of women in Graeco-Roman society is analysed in terms of motifs found in 1 Timothy 2:9-15.
- Full Text:
- Date Issued: 1992
- Authors: Williams, Allan Alexander
- Date: 1992
- Subjects: Bible -- Criticism, interpretation, etc. , Women in the Bible , Women in Christianity -- History -- Early church, ca. 30-600 , Women in Christianity , Sexism in religion
- Language: English
- Type: Thesis , Masters , MTh
- Identifier: vital:1299 , http://hdl.handle.net/10962/d1015721
- Description: This thesis investigates the role of women in the early church as portrayed in 1 Timothy 2:9-15 using the recently-developed method of Rhetorical Analysis. It makes use of a rhetorical approach largely based on the method proposed by Kennedy, supplemented by insights from scholars who have emphasised the argumentative element in rhetoric. This method illustrates how the role of women in the church is decisively determined by the argument in the letter as a whole. A brief survey of classical rhetoric is given. The typical structure of a rhetorical discourse is listed with its component sections. The validity of using rhetorical analysis as a means for interpreting New Testament texts is justified. Textual units are identified from the structure of the text. Rhetorical insights are used to explain how the identified units cohere within the overall structure of the letter and how they relate to one another and interact. The thesis is developed that the section on women and teaching can only be meaningfully investigated in the light of the text as a whole and of the motifs in the letter. The thesis has a special focus on 2:9-15. This section is analysed in more detail than the rest of the text with the exception of 1 Timothy 1. As exordium, the latter provides the introduction to the situation dealt with in the letter, introduces the case, and sets the tone for the rest of the letter. The persuasive power of rhetoric in any situation depends to a large extent on its use of common tradition. The socio-cultural setting of the author is consequently analysed. Finally, the role of women in Graeco-Roman society is analysed in terms of motifs found in 1 Timothy 2:9-15.
- Full Text:
- Date Issued: 1992
The relationship of general retention ability to new South African group test non-verbal/verbal IQ discrepancies and their academic correlates
- Authors: Watson, Peter James
- Date: 1992
- Subjects: Intellect Intelligence tests -- South Africa Academic achievement -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1725 , http://hdl.handle.net/10962/d1003608
- Description: Both experimental research (Robbertse,1952)and clinical observation (Kruger, 1972; van der Merwe,1978) have indicated that pupils with a Verbal IQ score 10 or more points lower than their non-Verbal IQ (termed a 'Type 1' discrepancy in the present research) on the New South African Group Test (NSAGT) show poorer academic achievement than their peers of similar ability. The present research investigates the relationship of general retention ability, as defined by Hakstian and Cattell (1978), to Type 1 discrepancies as well as to their academic correlates. One hundred and thirty-nine standard seven English-speaking boys were tested on the NSAGT and the Junior Aptitude Test (JAT) (of which tests 8 and 9 give an indication of general retention ability) and divided into a group with Type 1 discrepancies and two control groups. All three groups were matched on full-scale IQ. Comparison of these three groups, using the analysis of variance technique, showed that there was no significant difference between them in level of general retention ability or in academic performance (measured by average percentage in the final standard seven examination). While no significant difference was found between the three groups regarding the relationship of general retention ability to academic performance, in the Type 1 discrepancy group the relationship of rote memory (JAT test 8) to academic performance differed markedly from that of associative memory (JAT test 9) to academic performance. In the Type 1 discrepancy group rote memory was highly associated with academic performance, possibly indicating a compensatory strategy for the lower Verbal ability in this group, enabling it to achieve academically on par with the control groups, contrary to what would be expected on the basis of Robbertse's (1962) findings. In terms of Jensen's (1982) Level 1/Level 11 theory of intelligence, it appears from the present research that rote memory ability (JAT test 8) varies between being a Level 11 ability (in the Type 1 discrepancy group) to acting as a Level 1 ability in the two control groups. The present research questions Verwey and Wolmarans's (1980) description of both JAT tests 8 and 9 as simple measures of retention Test 9, in particular, appears to function consistently as a Level 11 ability.
- Full Text:
- Date Issued: 1992
- Authors: Watson, Peter James
- Date: 1992
- Subjects: Intellect Intelligence tests -- South Africa Academic achievement -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1725 , http://hdl.handle.net/10962/d1003608
- Description: Both experimental research (Robbertse,1952)and clinical observation (Kruger, 1972; van der Merwe,1978) have indicated that pupils with a Verbal IQ score 10 or more points lower than their non-Verbal IQ (termed a 'Type 1' discrepancy in the present research) on the New South African Group Test (NSAGT) show poorer academic achievement than their peers of similar ability. The present research investigates the relationship of general retention ability, as defined by Hakstian and Cattell (1978), to Type 1 discrepancies as well as to their academic correlates. One hundred and thirty-nine standard seven English-speaking boys were tested on the NSAGT and the Junior Aptitude Test (JAT) (of which tests 8 and 9 give an indication of general retention ability) and divided into a group with Type 1 discrepancies and two control groups. All three groups were matched on full-scale IQ. Comparison of these three groups, using the analysis of variance technique, showed that there was no significant difference between them in level of general retention ability or in academic performance (measured by average percentage in the final standard seven examination). While no significant difference was found between the three groups regarding the relationship of general retention ability to academic performance, in the Type 1 discrepancy group the relationship of rote memory (JAT test 8) to academic performance differed markedly from that of associative memory (JAT test 9) to academic performance. In the Type 1 discrepancy group rote memory was highly associated with academic performance, possibly indicating a compensatory strategy for the lower Verbal ability in this group, enabling it to achieve academically on par with the control groups, contrary to what would be expected on the basis of Robbertse's (1962) findings. In terms of Jensen's (1982) Level 1/Level 11 theory of intelligence, it appears from the present research that rote memory ability (JAT test 8) varies between being a Level 11 ability (in the Type 1 discrepancy group) to acting as a Level 1 ability in the two control groups. The present research questions Verwey and Wolmarans's (1980) description of both JAT tests 8 and 9 as simple measures of retention Test 9, in particular, appears to function consistently as a Level 11 ability.
- Full Text:
- Date Issued: 1992
Managing historical primary and secondary sources : a study of the efficacy of a teaching handbook prepared for first-year Vista University students
- Authors: Watson, Kelvin Innes
- Date: 1992
- Subjects: History -- Study and teaching (Secondary) -- South Africa History -- Study and teaching (Higher) -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1670 , http://hdl.handle.net/10962/d1003553
- Description: This study examines the teaching of primary and secondary sources in history at secondary and tertiary level. The various methods used to teach these aspects of the nature of history are compared to the Vista University teaching model. To establish the effectiveness of the vista Block A module for HIS100 students, two test instruments were devised to assess their skills in handling primary and secondary sources. Their skills in identifying relevant points from a passage of historical prose were also tested. A number of statistical techniques were applied to the data from the test instruments. This data was analysed in qualitative and quantitative terms. The results of this analysis suggested that students would probably benefit from a skills-orientated approach to studying history. On the basis of this study, it is recommended that the existing Vista teaching model be revised or amended so that a more effective method of teaching students about the nature of historical sources can be introduced.
- Full Text:
- Date Issued: 1992
- Authors: Watson, Kelvin Innes
- Date: 1992
- Subjects: History -- Study and teaching (Secondary) -- South Africa History -- Study and teaching (Higher) -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1670 , http://hdl.handle.net/10962/d1003553
- Description: This study examines the teaching of primary and secondary sources in history at secondary and tertiary level. The various methods used to teach these aspects of the nature of history are compared to the Vista University teaching model. To establish the effectiveness of the vista Block A module for HIS100 students, two test instruments were devised to assess their skills in handling primary and secondary sources. Their skills in identifying relevant points from a passage of historical prose were also tested. A number of statistical techniques were applied to the data from the test instruments. This data was analysed in qualitative and quantitative terms. The results of this analysis suggested that students would probably benefit from a skills-orientated approach to studying history. On the basis of this study, it is recommended that the existing Vista teaching model be revised or amended so that a more effective method of teaching students about the nature of historical sources can be introduced.
- Full Text:
- Date Issued: 1992
The status of the American bollworm, Heliothis armigera (Hubner) (Lepidoptera : Noctuidae), on sunflower in the central Transvaal
- Authors: Von Maltitz, Emil Friedrich
- Date: 1992
- Subjects: Helicoverpa armigera , Noctuidae -- South Africa -- Transvaal , Noctuidae , Sunflowers -- Diseases and pests
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5773 , http://hdl.handle.net/10962/d1005461 , Helicoverpa armigera , Noctuidae -- South Africa -- Transvaal , Noctuidae , Sunflowers -- Diseases and pests
- Description: Sunflower production in South Africa has increased four fold since the 1970's. This study was done to elucidate the pest status of Heliothis armigera (Hiibner) on sunflower. Field studies were undertaken at Warmbaths, Brits and Delmas during the summer seasons of 1988/89 to 1990/91. The infestations at the latter two areas were negligible throughout the study period and their statistics have not been included in this thesis. Plant development and oviposition by natural H. armigera populations were found to be correlated as, regardless of planting date, oviposition started at six to seven weeks after planting; when the flowering stage began. A peak in egg numbers was reached by the tenth week with an average for the three seasons at two eggs per plant. The eggs were laid singly on the bracts and bases of the flower buds. A peak in larval numbers was reached at the thirteenth week after planting with the average for the three seasons of 0,4 larvae per plant. The preferred feeding sites were on, between and under the bracts from where the larvae burrow into the pithy tissue of the receptacle. Only six percent of the larvae were found feeding directly on the achenes. Eggs and larvae collected were reared to determine the degree of parasitism. Overall, 19% of the eggs were parasitised; 18% by Telenomus ullyetti Nixon (Scelionidae) and one percent by Trichogrammatoidea lutea (Trichogrammatidae). Larval parasitism at Warmbaths was 23% in 1988/89, 27% in 1989/90 and 34% in 1990/91. Of the parasitised larvae, 44% succumbed to Palexorista prob. laxa (Tachinidae). The remainder were unidentified Braconidae and Ichneumonidae. Predators, such as chrysopids, were observed during the study but their effect on egg and larvae numbers was not studied in detail. A polyhedral virus occurred late in the seasons and caused mortality of the larvae. The low numbers of H. armigera on sunflower, the slight damage to the crop and the reasonably high rate of parasitism, all seem to indicate that H. armigera is not an economica1ly important pest of sunflower and that additional control methods are not justified.
- Full Text:
- Date Issued: 1992
- Authors: Von Maltitz, Emil Friedrich
- Date: 1992
- Subjects: Helicoverpa armigera , Noctuidae -- South Africa -- Transvaal , Noctuidae , Sunflowers -- Diseases and pests
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5773 , http://hdl.handle.net/10962/d1005461 , Helicoverpa armigera , Noctuidae -- South Africa -- Transvaal , Noctuidae , Sunflowers -- Diseases and pests
- Description: Sunflower production in South Africa has increased four fold since the 1970's. This study was done to elucidate the pest status of Heliothis armigera (Hiibner) on sunflower. Field studies were undertaken at Warmbaths, Brits and Delmas during the summer seasons of 1988/89 to 1990/91. The infestations at the latter two areas were negligible throughout the study period and their statistics have not been included in this thesis. Plant development and oviposition by natural H. armigera populations were found to be correlated as, regardless of planting date, oviposition started at six to seven weeks after planting; when the flowering stage began. A peak in egg numbers was reached by the tenth week with an average for the three seasons at two eggs per plant. The eggs were laid singly on the bracts and bases of the flower buds. A peak in larval numbers was reached at the thirteenth week after planting with the average for the three seasons of 0,4 larvae per plant. The preferred feeding sites were on, between and under the bracts from where the larvae burrow into the pithy tissue of the receptacle. Only six percent of the larvae were found feeding directly on the achenes. Eggs and larvae collected were reared to determine the degree of parasitism. Overall, 19% of the eggs were parasitised; 18% by Telenomus ullyetti Nixon (Scelionidae) and one percent by Trichogrammatoidea lutea (Trichogrammatidae). Larval parasitism at Warmbaths was 23% in 1988/89, 27% in 1989/90 and 34% in 1990/91. Of the parasitised larvae, 44% succumbed to Palexorista prob. laxa (Tachinidae). The remainder were unidentified Braconidae and Ichneumonidae. Predators, such as chrysopids, were observed during the study but their effect on egg and larvae numbers was not studied in detail. A polyhedral virus occurred late in the seasons and caused mortality of the larvae. The low numbers of H. armigera on sunflower, the slight damage to the crop and the reasonably high rate of parasitism, all seem to indicate that H. armigera is not an economica1ly important pest of sunflower and that additional control methods are not justified.
- Full Text:
- Date Issued: 1992
Genetic models for epithermal gold deposits and applications to exploration
- Authors: Veselinović, Milica
- Date: 1992
- Subjects: Gold ores -- Geology , Hydrothermal deposits
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4950 , http://hdl.handle.net/10962/d1005562 , Gold ores -- Geology , Hydrothermal deposits
- Description: Epithermal gold deposits are the product of large-scale hydrothermal systems in tectonically active regions. They form at shallow crustal levels where the physico-chemical conditions change abruptly. Two major groups of epithermal gold deposits can be distinguished based on their genetic connection with: A) Copper-molybdenum porphyry systems and B) Geothermal systems related to volcanic centres and calderas. Epithermal gold deposits connected with geothermal systems encompass three major types: adularia-sericite, acid-sulphate and disseminated replacement (the Carlin-type). Their essential ingredients are: high heat source which leads to convection of groundwater in the upper crust; source of hydrothermal fluid, metals and reduced sulphur; and high-permeability structures which allow fluid convection and metal deposition. Mixing of these ingredients leads to the formation of epithermal gold deposits throughout crustal history, without any restriction on age. The ores were deposited from near-neutral (adularia-sericite type and some of the Carlin-type) to acidic (acid-sulphate type and porphyry-related epithermal gold deposits), low-salinity, high C0₂ and high H₂S fluids, which were predominantly meteoritic in origin. The transport capability of deep fluids in epithermal hydrothermal systems may be shown to be dependent largely on their H₂S content and, through a series of fluid mineral equilibria, on temperature and on C0₂ content. The most common mechanisms of ore deposition are boiling (phase separation), mixing of fluids of different temperatures and salinities, reaction between them and wall rocks, dilution and cooling. An understanding of genetic models for epithermal gold deposits provides the basis for the selection of favourable areas for regional to prospect-scale exploration.
- Full Text:
- Date Issued: 1992
- Authors: Veselinović, Milica
- Date: 1992
- Subjects: Gold ores -- Geology , Hydrothermal deposits
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4950 , http://hdl.handle.net/10962/d1005562 , Gold ores -- Geology , Hydrothermal deposits
- Description: Epithermal gold deposits are the product of large-scale hydrothermal systems in tectonically active regions. They form at shallow crustal levels where the physico-chemical conditions change abruptly. Two major groups of epithermal gold deposits can be distinguished based on their genetic connection with: A) Copper-molybdenum porphyry systems and B) Geothermal systems related to volcanic centres and calderas. Epithermal gold deposits connected with geothermal systems encompass three major types: adularia-sericite, acid-sulphate and disseminated replacement (the Carlin-type). Their essential ingredients are: high heat source which leads to convection of groundwater in the upper crust; source of hydrothermal fluid, metals and reduced sulphur; and high-permeability structures which allow fluid convection and metal deposition. Mixing of these ingredients leads to the formation of epithermal gold deposits throughout crustal history, without any restriction on age. The ores were deposited from near-neutral (adularia-sericite type and some of the Carlin-type) to acidic (acid-sulphate type and porphyry-related epithermal gold deposits), low-salinity, high C0₂ and high H₂S fluids, which were predominantly meteoritic in origin. The transport capability of deep fluids in epithermal hydrothermal systems may be shown to be dependent largely on their H₂S content and, through a series of fluid mineral equilibria, on temperature and on C0₂ content. The most common mechanisms of ore deposition are boiling (phase separation), mixing of fluids of different temperatures and salinities, reaction between them and wall rocks, dilution and cooling. An understanding of genetic models for epithermal gold deposits provides the basis for the selection of favourable areas for regional to prospect-scale exploration.
- Full Text:
- Date Issued: 1992
Standardization of Raven's standard progressive matrices for secondary school African pupils in the Grahamstown region
- Authors: Vass, Vasili Arthur
- Date: 1992
- Subjects: Black people -- Education -- South Africa , Intelligence tests -- South Africa , Educational tests and measurements -- South Africa , Cognition and culture , Raven's Progressive Matrices
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3078 , http://hdl.handle.net/10962/d1002587 , Black people -- Education -- South Africa , Intelligence tests -- South Africa , Educational tests and measurements -- South Africa , Cognition and culture , Raven's Progressive Matrices
- Description: Arising out of a need, expressed by Clinical Psychologists in the Grahamstown region, for the fair assessment of secondary School African pupils, norms for the Raven's Standard Progressive Matrices (SPM) were established. Two methods of presentation were used, the first using the original instructions of John Raven translated into the students' first language of Xhosa, hence-forth referred to as the Alternate sample. The second method of presenting the instructions was adapted, to include the use of visual aids and active participation in the instruction phase of the test, hence-forth referred to as the Normative sample. In addition to the establishment of norms, the two methods of test presentation were investigated to see if the method of presentation had an effect on the results of the Raven's SPM. The population was drawn from the three African Secondary Schools in the Grahamstown municipality. The total population consisted of 3 232 students. Classes were randomly sampled across the three schools, with the average age of the Normative sample being 19.3 years. The sample consisted of 812 pupils, 711 in the Normative sample and 101 in the Alternate Sample. The following results and conclusions arose from the study: 1) Norms generated were considerably lower than previously established norms in similar studies. 2) t-Test results indicated that the method of test presentation on the Raven's SPM is important when assessing students that may be regarded as 'disadvantaged'. 3) Respondents scored significantly higher when the method of presenting the instructions ensured a greater understanding of the task demanded of the respondents. 4) The analyses of covariance indicate that male subjects score significantly higher than female subjects, and that there is a significant difference between the ages and educational standard, on the scores of the Raven's SPM. 5) The differences found contradict previous findings using the test, and question the cultural fairness of the test.
- Full Text:
- Date Issued: 1992
- Authors: Vass, Vasili Arthur
- Date: 1992
- Subjects: Black people -- Education -- South Africa , Intelligence tests -- South Africa , Educational tests and measurements -- South Africa , Cognition and culture , Raven's Progressive Matrices
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3078 , http://hdl.handle.net/10962/d1002587 , Black people -- Education -- South Africa , Intelligence tests -- South Africa , Educational tests and measurements -- South Africa , Cognition and culture , Raven's Progressive Matrices
- Description: Arising out of a need, expressed by Clinical Psychologists in the Grahamstown region, for the fair assessment of secondary School African pupils, norms for the Raven's Standard Progressive Matrices (SPM) were established. Two methods of presentation were used, the first using the original instructions of John Raven translated into the students' first language of Xhosa, hence-forth referred to as the Alternate sample. The second method of presenting the instructions was adapted, to include the use of visual aids and active participation in the instruction phase of the test, hence-forth referred to as the Normative sample. In addition to the establishment of norms, the two methods of test presentation were investigated to see if the method of presentation had an effect on the results of the Raven's SPM. The population was drawn from the three African Secondary Schools in the Grahamstown municipality. The total population consisted of 3 232 students. Classes were randomly sampled across the three schools, with the average age of the Normative sample being 19.3 years. The sample consisted of 812 pupils, 711 in the Normative sample and 101 in the Alternate Sample. The following results and conclusions arose from the study: 1) Norms generated were considerably lower than previously established norms in similar studies. 2) t-Test results indicated that the method of test presentation on the Raven's SPM is important when assessing students that may be regarded as 'disadvantaged'. 3) Respondents scored significantly higher when the method of presenting the instructions ensured a greater understanding of the task demanded of the respondents. 4) The analyses of covariance indicate that male subjects score significantly higher than female subjects, and that there is a significant difference between the ages and educational standard, on the scores of the Raven's SPM. 5) The differences found contradict previous findings using the test, and question the cultural fairness of the test.
- Full Text:
- Date Issued: 1992
The administration and organisation of independent study topics with special reference to secondary school geography
- Authors: Van Harmelen, U
- Date: 1992
- Subjects: Geography -- Study and teaching (Secondary) , Project method in teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1419 , http://hdl.handle.net/10962/d1003300
- Description: Traditional school subjects are having to compete for a place in a curriculum which is increasingly judged according to its perceived utilitarian value. According to current educational theory, geography's role in the curriculum is to develop concepts, skills, values and attitudes that allow pupils to understand the human and environmental issues which face their communities and communities throughout the world. In order to achieve these aims, teachers need to adopt a learner-centred teaching approach, yet geography teachers are faced with the dilemma of having to develop participatory teaching strategies within an existing structure which is largely product oriented. This thesis attempts to illustrate how changes can be effected in the approach to the teaching of geography, while working within existing syllabus constraints and while continuing to meet the demands made by the current examination system. To this end, Independent Study Topics are analysed as a means to bring about the desired changes in geographical education. The concept, Independent Study Topics as a 'blanket term' (Diepeveen, 1986) for pupil-centred activities is relatively recent in terms of the South African geography syllabus. In order to obtain greater clarity about the concept and its implications for geography teaching, this study examines current geographical theory relating to learner-centred approaches and relates them to teachers' perceptions of the role of IST in the geography curriculum. The second aspect of the study is concerned with the implementation of Independent Study Topics in a classroom research setting. The organisation and administration of Independent Study Topics in a single school setting is analysed and evaluated as a process of change. This analysis provides guidelines for developing a learner-centred approach which is necessary to ensure that geography retains its position in the school curriculum of the 1990's and beyond.
- Full Text:
- Date Issued: 1992
- Authors: Van Harmelen, U
- Date: 1992
- Subjects: Geography -- Study and teaching (Secondary) , Project method in teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1419 , http://hdl.handle.net/10962/d1003300
- Description: Traditional school subjects are having to compete for a place in a curriculum which is increasingly judged according to its perceived utilitarian value. According to current educational theory, geography's role in the curriculum is to develop concepts, skills, values and attitudes that allow pupils to understand the human and environmental issues which face their communities and communities throughout the world. In order to achieve these aims, teachers need to adopt a learner-centred teaching approach, yet geography teachers are faced with the dilemma of having to develop participatory teaching strategies within an existing structure which is largely product oriented. This thesis attempts to illustrate how changes can be effected in the approach to the teaching of geography, while working within existing syllabus constraints and while continuing to meet the demands made by the current examination system. To this end, Independent Study Topics are analysed as a means to bring about the desired changes in geographical education. The concept, Independent Study Topics as a 'blanket term' (Diepeveen, 1986) for pupil-centred activities is relatively recent in terms of the South African geography syllabus. In order to obtain greater clarity about the concept and its implications for geography teaching, this study examines current geographical theory relating to learner-centred approaches and relates them to teachers' perceptions of the role of IST in the geography curriculum. The second aspect of the study is concerned with the implementation of Independent Study Topics in a classroom research setting. The organisation and administration of Independent Study Topics in a single school setting is analysed and evaluated as a process of change. This analysis provides guidelines for developing a learner-centred approach which is necessary to ensure that geography retains its position in the school curriculum of the 1990's and beyond.
- Full Text:
- Date Issued: 1992
The surface geology of the Lavino Chrome Mine of the farm Grootboom 336KT, eastern Transvaal
- Authors: Tinney, Christopher Bruce
- Date: 1992
- Subjects: Chromium ores -- Geology -- South Africa -- Mpumalanga
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5067 , http://hdl.handle.net/10962/d1013404
- Description: A mapping project of the surface geology of the Lavino chrome mine and its surroundings was initiated in order to establish the surface geological relationships in the area. In so doing the chromitite layer presently being mined has been identified and potential exploration targets in the area have been outlined. The Lavino Chrome mine field area is situated within the eastern lobe of the Bushveld Igneous Complex. The area is bounded by in the north by the Steelpoort Lineament, in the west by the Dwars River fault and in the east by the contact with the Transvaal Sequence floor rocks. Layered igneous rocks (pyroxenites, norites and anorthosites) of the Rustenburg Layered Suite dominate the geological landscape at the Lavino mine. The fact that outcropping igneous rocks of the Critical Zone abut directly against the quartzite floor rocks on the mine property makes this area unique in the Bushveld Complex. The hills in the field area are capped by mafic/ultramafic iron-rich sheet - like bodies. Extensive strike-slip faulting is seen in outcrop in the area to the north/northwest of present mining operations. On the basis of field relationships, the main chromitite layer presently being mined at Lavino is identified as the Middle Group chromitite layer MG 1. Three other prominent chromitite layers stratigraphically associated with MG 1 are identified as the Middle Group chromitites MG 2, MG 3 and MG 4. Several other less prominent outcropping chromitite layers are tentatively identified as those belonging to the Lower and Upper group of chromitites. The disconformable nature of the contact between the layered igneous rocks and the Transvaal Sequence floor rocks has resulted in the development of a wedge of undifferentiated pyroxenites in the north of the field area. The economically important LG 6 chromitite layer may be developed in subcrop within this wedge.
- Full Text:
- Date Issued: 1992
- Authors: Tinney, Christopher Bruce
- Date: 1992
- Subjects: Chromium ores -- Geology -- South Africa -- Mpumalanga
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5067 , http://hdl.handle.net/10962/d1013404
- Description: A mapping project of the surface geology of the Lavino chrome mine and its surroundings was initiated in order to establish the surface geological relationships in the area. In so doing the chromitite layer presently being mined has been identified and potential exploration targets in the area have been outlined. The Lavino Chrome mine field area is situated within the eastern lobe of the Bushveld Igneous Complex. The area is bounded by in the north by the Steelpoort Lineament, in the west by the Dwars River fault and in the east by the contact with the Transvaal Sequence floor rocks. Layered igneous rocks (pyroxenites, norites and anorthosites) of the Rustenburg Layered Suite dominate the geological landscape at the Lavino mine. The fact that outcropping igneous rocks of the Critical Zone abut directly against the quartzite floor rocks on the mine property makes this area unique in the Bushveld Complex. The hills in the field area are capped by mafic/ultramafic iron-rich sheet - like bodies. Extensive strike-slip faulting is seen in outcrop in the area to the north/northwest of present mining operations. On the basis of field relationships, the main chromitite layer presently being mined at Lavino is identified as the Middle Group chromitite layer MG 1. Three other prominent chromitite layers stratigraphically associated with MG 1 are identified as the Middle Group chromitites MG 2, MG 3 and MG 4. Several other less prominent outcropping chromitite layers are tentatively identified as those belonging to the Lower and Upper group of chromitites. The disconformable nature of the contact between the layered igneous rocks and the Transvaal Sequence floor rocks has resulted in the development of a wedge of undifferentiated pyroxenites in the north of the field area. The economically important LG 6 chromitite layer may be developed in subcrop within this wedge.
- Full Text:
- Date Issued: 1992
"Constructive critic" or "donor agency": does the World Bank have a role to play in sub-Saharan Africa's development beyond that of providing economic aid?
- Authors: Thompson, Christine Audra
- Date: 1992
- Subjects: Africa, Sub-Saharan -- Economic conditions -- 20th century , World Bank -- Africa, Sub-Saharan , Africa, Sub-Saharan -- Economic conditions
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2835 , http://hdl.handle.net/10962/d1003045 , Africa, Sub-Saharan -- Economic conditions -- 20th century , World Bank -- Africa, Sub-Saharan , Africa, Sub-Saharan -- Economic conditions
- Description: This thesis attempts to evaluate the role of the World Bank in Sub-Saharan Africa's development. It argues that the World Bank has stepped beyond the boundaries of a typical lending institution by linking its aid to political reform. The study argues that in this capacity the Bank has contributed to the halting democratization process currently underway in Africa. The economic effects of the World Bank's Structural Adjustment Programmes have been less successful. As yet, the programmes have not produced the expected results and there is no evidence of long-term, sustainable economic recovery in Sub-Saharan Africa. These programmes are, however, long-term strategies and it may therefore be too premature to reach a final conclusion. They may also have been affected negatively by unfavourable political environments. This study, noting the negative effects of the international terms of trade and prices for African exports, concludes that although economic recovery in Sub-Saharan Africa will be facilitated by domestic political and economic policy reform, there is also a need for reform of the international economic order. The World Bank has correctly identified the need for domestic improvement, but it has a tendency to disregard the negative consequences of the existing structure of the international economy.
- Full Text:
- Date Issued: 1992
- Authors: Thompson, Christine Audra
- Date: 1992
- Subjects: Africa, Sub-Saharan -- Economic conditions -- 20th century , World Bank -- Africa, Sub-Saharan , Africa, Sub-Saharan -- Economic conditions
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2835 , http://hdl.handle.net/10962/d1003045 , Africa, Sub-Saharan -- Economic conditions -- 20th century , World Bank -- Africa, Sub-Saharan , Africa, Sub-Saharan -- Economic conditions
- Description: This thesis attempts to evaluate the role of the World Bank in Sub-Saharan Africa's development. It argues that the World Bank has stepped beyond the boundaries of a typical lending institution by linking its aid to political reform. The study argues that in this capacity the Bank has contributed to the halting democratization process currently underway in Africa. The economic effects of the World Bank's Structural Adjustment Programmes have been less successful. As yet, the programmes have not produced the expected results and there is no evidence of long-term, sustainable economic recovery in Sub-Saharan Africa. These programmes are, however, long-term strategies and it may therefore be too premature to reach a final conclusion. They may also have been affected negatively by unfavourable political environments. This study, noting the negative effects of the international terms of trade and prices for African exports, concludes that although economic recovery in Sub-Saharan Africa will be facilitated by domestic political and economic policy reform, there is also a need for reform of the international economic order. The World Bank has correctly identified the need for domestic improvement, but it has a tendency to disregard the negative consequences of the existing structure of the international economy.
- Full Text:
- Date Issued: 1992
A cost-benefit analysis of electricity supply in a developing country, with reference to Venda
- Authors: Themeli, Tshimangadzo Booi
- Date: 1992
- Subjects: Electrification -- Economic aspects -- South Africa -- Venda , Electric utilities -- South Africa -- Venda , Cost effectiveness , Electrification -- Cost effectiveness
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1022 , http://hdl.handle.net/10962/d1002757 , Electrification -- Economic aspects -- South Africa -- Venda , Electric utilities -- South Africa -- Venda , Cost effectiveness , Electrification -- Cost effectiveness
- Description: This study concentrates specificaUy on assessing those elements of private and external costs and benefits which need to be accounted for in analyzing the role of electricity supply in a developing region. To facilitate this aim, three interrelated questions are addressed. The first question examines the reasons why a critical need for electrification in developing areas exists. In this regard, a selective review of the literature on development economics is offered, illuminating the previous neglect of the rural dimension in development and the associated problems of poverty and inequality, a lack of infrastructure and the general inability to fulfill basic needs. The second question is devoted exclusively to an economic analysis of the supply of electricity in developing areas. A broad theoretical review on whether an unregulated or regulated (private or public) sector should be responsible for the provision of electrification is presented. This evaluation highlights the various welfare implications and efficiency considerations that appear to be relevant in the present context. The final question, which constitutes the central proposition of the thesis, establishes how electrification should be supplied in developing areas. To this end, the conditions specific to a region in Venda are discussed. An attempt is made to identify the private and external costs and benefits relating to electricity supply and the corresponding costs and benefits pertaining to alternative sources of energy. Since the incidence and nature of these costs and benefits could only be ascertained from individual households, it was deemed necessary to undertake a questionnaire study of residents in Makwarela township and its periurban settlement of Lufule-Tshisele. A number of basic trends were evident from the research results. As far as the various benefits are concerned, respondents tended to place a much higher value on both the private and external benefits associated with electricity than its alternatives. At the same time, the survey found that although the private (or monetary) cost of electricity far exceeded the corresponding cost of alternative energy sources, the external costs were significant in the case of alternative energy sources, but virtually non-existent in the case of electricity. On the whole, the Venda survey seems to suggest that an economic case can be made for involving the broader community in subsidising the supply of electricity in Makwarela, Lufule-Tshisele and other areas. While such a subsidy can perhaps be justified on distribution grounds alone, and more specifically in terms of the rapid and pronounced effect it is likely to have on the quality of life in the region, its real worth lies in the fact that it may confer certain external benefits on the community.
- Full Text:
- Date Issued: 1992
- Authors: Themeli, Tshimangadzo Booi
- Date: 1992
- Subjects: Electrification -- Economic aspects -- South Africa -- Venda , Electric utilities -- South Africa -- Venda , Cost effectiveness , Electrification -- Cost effectiveness
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1022 , http://hdl.handle.net/10962/d1002757 , Electrification -- Economic aspects -- South Africa -- Venda , Electric utilities -- South Africa -- Venda , Cost effectiveness , Electrification -- Cost effectiveness
- Description: This study concentrates specificaUy on assessing those elements of private and external costs and benefits which need to be accounted for in analyzing the role of electricity supply in a developing region. To facilitate this aim, three interrelated questions are addressed. The first question examines the reasons why a critical need for electrification in developing areas exists. In this regard, a selective review of the literature on development economics is offered, illuminating the previous neglect of the rural dimension in development and the associated problems of poverty and inequality, a lack of infrastructure and the general inability to fulfill basic needs. The second question is devoted exclusively to an economic analysis of the supply of electricity in developing areas. A broad theoretical review on whether an unregulated or regulated (private or public) sector should be responsible for the provision of electrification is presented. This evaluation highlights the various welfare implications and efficiency considerations that appear to be relevant in the present context. The final question, which constitutes the central proposition of the thesis, establishes how electrification should be supplied in developing areas. To this end, the conditions specific to a region in Venda are discussed. An attempt is made to identify the private and external costs and benefits relating to electricity supply and the corresponding costs and benefits pertaining to alternative sources of energy. Since the incidence and nature of these costs and benefits could only be ascertained from individual households, it was deemed necessary to undertake a questionnaire study of residents in Makwarela township and its periurban settlement of Lufule-Tshisele. A number of basic trends were evident from the research results. As far as the various benefits are concerned, respondents tended to place a much higher value on both the private and external benefits associated with electricity than its alternatives. At the same time, the survey found that although the private (or monetary) cost of electricity far exceeded the corresponding cost of alternative energy sources, the external costs were significant in the case of alternative energy sources, but virtually non-existent in the case of electricity. On the whole, the Venda survey seems to suggest that an economic case can be made for involving the broader community in subsidising the supply of electricity in Makwarela, Lufule-Tshisele and other areas. While such a subsidy can perhaps be justified on distribution grounds alone, and more specifically in terms of the rapid and pronounced effect it is likely to have on the quality of life in the region, its real worth lies in the fact that it may confer certain external benefits on the community.
- Full Text:
- Date Issued: 1992
A study of the biopharmaceutics and pharmacokinetics of the macrolide antibiotic, erythromycin
- Authors: Terespolsky, Susan Ann
- Date: 1992
- Subjects: Erythromycin -- Bioavailability , Erythromycin -- Pharmacokinetics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3795 , http://hdl.handle.net/10962/d1003273 , Erythromycin -- Bioavailability , Erythromycin -- Pharmacokinetics
- Description: Erythromycin, a macrolide antibiotic isolated from Streptomyces erythreus, was first introduced into clinical medicine in 1952. It is active against most gram-positive bacteria, some gram-negative bacteria and is currently the agent of choice for Legionella pneumophila. Erythromycin is an acid-labile compound rapidly degrading in acidic solutions such as the acid environment of the stomach. As such, erythromycin absorption following oral administration of solid dosage forms is relatively poor. Accordingly there have been various approaches used to protect the drug against gastric inactivation. These precautions include enteric-coating of tablets, capsules or pellets of erythromycin base, the synthesis of acid stable 2' esters of erythromycin (ethylsuccinate and propionate) and salts of these esters (erythromycin estolate), and more recently, the synthesis of a range of new acid-stable, semi-synthetic macrolide antibiotics. The 2' esters are antimicrobially inactive or much less active than the parent compound and must be converted to the free erythromycin base in vivo in order to exhibit antibacterial activity. Intrinsic dissolution rates determined on raw material can provide extremely useful information relating to the gastrointestinal absorption of drugs from solid dosage forms. The large inter- and intrasubject variability associated with erythromycin base has, to date, mainly been attributed to gastric acid inactivation of the drug. However, changes in duodenal pH resulting in altered solubility and intrinsic dissolution rates may account for the observed variability. Thus, the intrinsic dissolution rates of erythromycin base at pH 6.0, 6.5, 7.0, 7.5 and 8.0 were compared in order to investigate the possible effects of pH changes which may occur in the duodenal contents, on the in vivo dissolution and subsequent absorption of this compound. The standard intrinsic dissolution rate test procedure employing a rotating disc of pure erythromycin base powder which only allows for dissolution from a constant surface area, was adapted and the drug quantitatively determined by reversed phase high performance liquid chromatography (HPLC) using ultraviolet detection. Results of intrinsic dissolution studies at both 22°C and 37°C indicate that the solubility, and therefore the rate of dissolution of erythromycin base is pH dependent, being more soluble at pH 6.0 than pH 8.0 (an approximate 800 times and 1000 times reduction in the amount dissolved after 30 minutes, at 22°C and 37°C respectively, when the pH of the medium was increased from 6 to 8). Although the stability of erythromycin and its ester derivatives in aqueous acidic solutions has been well documented, very little has been reported on the compound's stability in organic solvents. Methanol is recommended by official drug compendia (U.S.P. and B.P.) for use in erythromycin identification tests as well as in the sample preparation steps during assay procedures. Thus, the effect of methanol and acetonitrile, organic solvents of similar polarities and densities, on the stability of erythromycin base, erythromycin ethylsuccinate, propionyl erythromycin and erythromycin estolate at room temperature (22°C ± 0.5°C), using HPLC with electrochemical detection, was investigated. Erythromycin base is relatively stable in both methanol and acetonitrile, remaining intact for over 168 hours in acetonitrile and showing less than 5% degradation in methanol over the same period. Erythromycin ethylsuccinate in acetonitrile shows less than 5% degradation over 168 hours whereas in methanol, rapid hydrolysis occurs resulting in almost total conversion to base within 40 hours. Approximately 87% of erythromycin propionyl ester remained intact after 168 hours in acetonitrile whilst methanol caused rapid hydrolysis to erythromycin base (35% remaining after 28 hours). Erythromycin estolate appeared to be unstable in both acetonitrile and methanol. In acetonitrile, only 13% of the estolate remained intact after 168 hours, whereas in methanol, the reaction was much more rapid with 35% of the estolate remaining after 28 hours. The use of methanol as a solvent for erythromycin estolate reference standards is thus contraindicated. A number of conflicting reports on the half- life as well as the body compartment model that best describes erythromycin base serum concentration-time profiles (lBCM generally used to describe orally administered erythromycin, whilst a 2BCM has been used to describe erythromycin administered intravenously), appear in the literature. These differences may be largely attributed to the sampling period (between 6 and 12 hours) used in the repective studies. The objective of this study was to determine the body compartment model that best describes erythromycin base serum concentration-time curves by increasing the sampling time to 24 hours. In addition, the effect of chronic dosing of erythromycin on erythromycin pharmacokinetics, in the same group of subjects, was investigated. The single and multiple oral dose pharmacokinetics of erythromycin enteric coated base pellets within a gelatin capsule (250mg), were studied in 6 healthy, normal volunteers (19.5 ± 0.76 years, 71.5 ± 8.18 kg, 180.33 ± 5.99 cm). Furthermore, steady state concentrations were predicted using the pharmacokinetic parameters obtained from the single dose study, and compared with those obtained in the multiple dose study. Plasma concentrations were determined using a sensitive high-performance liquid chromatographic method with electrochemical detection. For the single dose study, after a tlag of 2.5 ± 0.71 hr, Cmax (1.12 ± 0.47 μ/ml) was reached at a tmax of 4.08 ± 0.93 hr post dose, with serum concentrations ranging from 0.31 - 1.62 μ/ml. The half-life was found to be 5.42 ± 1.31 hr. On multiple dosing (250mg six hourly), serum concentrations for the fifth, ninth and thirteenth dosing intervals ranged from 0.67 - 2.92 μ/ml, 1.69 - 3.65 μ/ml and 0.61 - 3.01 μ/ml, occurring at 3.75 ± 0.69 hr, 3.17 ± 1.03 hr and 3.17 ± 1.03 hr post dose with a Cmax of 1.89 ± 0.68 μ/ml, 2.35 ± 0.70 μ/ml and 1.94 ± 0.74 μ/ml, respectively. The area under the serum concentration- time curve for the single dose study (AUC₀₋∞) was 4.67 ± 0.88 hr.μ/ml, whilst the AUC₀₋τ. for the fifth, ninth and thirteenth dosing intervals of the multiple dose study were 5.77 ± 1.76 hr.μ/ml, 6.46 ± 1.33 hr.μ/ml and 5.97 ± 2.36 hr.μ/ml respectively, indicating an approximately 33% increase in AUC on chronic dosing of erythromycin. The observed increase in AUC may be a result of increased bioavailability or a decrease in clearance on chronic dosing.
- Full Text: false
- Date Issued: 1992
- Authors: Terespolsky, Susan Ann
- Date: 1992
- Subjects: Erythromycin -- Bioavailability , Erythromycin -- Pharmacokinetics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3795 , http://hdl.handle.net/10962/d1003273 , Erythromycin -- Bioavailability , Erythromycin -- Pharmacokinetics
- Description: Erythromycin, a macrolide antibiotic isolated from Streptomyces erythreus, was first introduced into clinical medicine in 1952. It is active against most gram-positive bacteria, some gram-negative bacteria and is currently the agent of choice for Legionella pneumophila. Erythromycin is an acid-labile compound rapidly degrading in acidic solutions such as the acid environment of the stomach. As such, erythromycin absorption following oral administration of solid dosage forms is relatively poor. Accordingly there have been various approaches used to protect the drug against gastric inactivation. These precautions include enteric-coating of tablets, capsules or pellets of erythromycin base, the synthesis of acid stable 2' esters of erythromycin (ethylsuccinate and propionate) and salts of these esters (erythromycin estolate), and more recently, the synthesis of a range of new acid-stable, semi-synthetic macrolide antibiotics. The 2' esters are antimicrobially inactive or much less active than the parent compound and must be converted to the free erythromycin base in vivo in order to exhibit antibacterial activity. Intrinsic dissolution rates determined on raw material can provide extremely useful information relating to the gastrointestinal absorption of drugs from solid dosage forms. The large inter- and intrasubject variability associated with erythromycin base has, to date, mainly been attributed to gastric acid inactivation of the drug. However, changes in duodenal pH resulting in altered solubility and intrinsic dissolution rates may account for the observed variability. Thus, the intrinsic dissolution rates of erythromycin base at pH 6.0, 6.5, 7.0, 7.5 and 8.0 were compared in order to investigate the possible effects of pH changes which may occur in the duodenal contents, on the in vivo dissolution and subsequent absorption of this compound. The standard intrinsic dissolution rate test procedure employing a rotating disc of pure erythromycin base powder which only allows for dissolution from a constant surface area, was adapted and the drug quantitatively determined by reversed phase high performance liquid chromatography (HPLC) using ultraviolet detection. Results of intrinsic dissolution studies at both 22°C and 37°C indicate that the solubility, and therefore the rate of dissolution of erythromycin base is pH dependent, being more soluble at pH 6.0 than pH 8.0 (an approximate 800 times and 1000 times reduction in the amount dissolved after 30 minutes, at 22°C and 37°C respectively, when the pH of the medium was increased from 6 to 8). Although the stability of erythromycin and its ester derivatives in aqueous acidic solutions has been well documented, very little has been reported on the compound's stability in organic solvents. Methanol is recommended by official drug compendia (U.S.P. and B.P.) for use in erythromycin identification tests as well as in the sample preparation steps during assay procedures. Thus, the effect of methanol and acetonitrile, organic solvents of similar polarities and densities, on the stability of erythromycin base, erythromycin ethylsuccinate, propionyl erythromycin and erythromycin estolate at room temperature (22°C ± 0.5°C), using HPLC with electrochemical detection, was investigated. Erythromycin base is relatively stable in both methanol and acetonitrile, remaining intact for over 168 hours in acetonitrile and showing less than 5% degradation in methanol over the same period. Erythromycin ethylsuccinate in acetonitrile shows less than 5% degradation over 168 hours whereas in methanol, rapid hydrolysis occurs resulting in almost total conversion to base within 40 hours. Approximately 87% of erythromycin propionyl ester remained intact after 168 hours in acetonitrile whilst methanol caused rapid hydrolysis to erythromycin base (35% remaining after 28 hours). Erythromycin estolate appeared to be unstable in both acetonitrile and methanol. In acetonitrile, only 13% of the estolate remained intact after 168 hours, whereas in methanol, the reaction was much more rapid with 35% of the estolate remaining after 28 hours. The use of methanol as a solvent for erythromycin estolate reference standards is thus contraindicated. A number of conflicting reports on the half- life as well as the body compartment model that best describes erythromycin base serum concentration-time profiles (lBCM generally used to describe orally administered erythromycin, whilst a 2BCM has been used to describe erythromycin administered intravenously), appear in the literature. These differences may be largely attributed to the sampling period (between 6 and 12 hours) used in the repective studies. The objective of this study was to determine the body compartment model that best describes erythromycin base serum concentration-time curves by increasing the sampling time to 24 hours. In addition, the effect of chronic dosing of erythromycin on erythromycin pharmacokinetics, in the same group of subjects, was investigated. The single and multiple oral dose pharmacokinetics of erythromycin enteric coated base pellets within a gelatin capsule (250mg), were studied in 6 healthy, normal volunteers (19.5 ± 0.76 years, 71.5 ± 8.18 kg, 180.33 ± 5.99 cm). Furthermore, steady state concentrations were predicted using the pharmacokinetic parameters obtained from the single dose study, and compared with those obtained in the multiple dose study. Plasma concentrations were determined using a sensitive high-performance liquid chromatographic method with electrochemical detection. For the single dose study, after a tlag of 2.5 ± 0.71 hr, Cmax (1.12 ± 0.47 μ/ml) was reached at a tmax of 4.08 ± 0.93 hr post dose, with serum concentrations ranging from 0.31 - 1.62 μ/ml. The half-life was found to be 5.42 ± 1.31 hr. On multiple dosing (250mg six hourly), serum concentrations for the fifth, ninth and thirteenth dosing intervals ranged from 0.67 - 2.92 μ/ml, 1.69 - 3.65 μ/ml and 0.61 - 3.01 μ/ml, occurring at 3.75 ± 0.69 hr, 3.17 ± 1.03 hr and 3.17 ± 1.03 hr post dose with a Cmax of 1.89 ± 0.68 μ/ml, 2.35 ± 0.70 μ/ml and 1.94 ± 0.74 μ/ml, respectively. The area under the serum concentration- time curve for the single dose study (AUC₀₋∞) was 4.67 ± 0.88 hr.μ/ml, whilst the AUC₀₋τ. for the fifth, ninth and thirteenth dosing intervals of the multiple dose study were 5.77 ± 1.76 hr.μ/ml, 6.46 ± 1.33 hr.μ/ml and 5.97 ± 2.36 hr.μ/ml respectively, indicating an approximately 33% increase in AUC on chronic dosing of erythromycin. The observed increase in AUC may be a result of increased bioavailability or a decrease in clearance on chronic dosing.
- Full Text: false
- Date Issued: 1992
Exploratory studies of novel ligand systems
- Authors: Taylor, Steven John
- Date: 1992
- Subjects: Ligands , Coordination compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4315 , http://hdl.handle.net/10962/d1004973 , Ligands , Coordination compounds
- Description: A range of novel ligand systems have been developed in three distinct phases and preliminary studies have been initiated to evaluate their complexation potential. Phase I incorporated the synthesis of single strand ligand systems, which were mainly based on amino acid residues. Techniques have been developed for the attachment of these ligand systems onto, firstly, a styrene monomer, and then later onto a pseudo-styrene linking group, viz. the p-toluoyl group. The linking reactions were based on the formation of amides or esters by the reaction of an acid chloride system with an amine or alcohol. Phase II involved the synthesis of bis-chain ligand systems and their attachment onto the p-toluoyl linking group. A further linking group was also developed at this stage, viz. the xylyl group. In the preparation of phase II ligand systems, use was made of malonic ester and iminodiacetic acid derivatives. Phase III has involved the synthesis of cyclic ligand systems, with skeletons based upon the structures used in phase I and phase II and two crown ether type systems have been prepared.
- Full Text:
- Date Issued: 1992
- Authors: Taylor, Steven John
- Date: 1992
- Subjects: Ligands , Coordination compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4315 , http://hdl.handle.net/10962/d1004973 , Ligands , Coordination compounds
- Description: A range of novel ligand systems have been developed in three distinct phases and preliminary studies have been initiated to evaluate their complexation potential. Phase I incorporated the synthesis of single strand ligand systems, which were mainly based on amino acid residues. Techniques have been developed for the attachment of these ligand systems onto, firstly, a styrene monomer, and then later onto a pseudo-styrene linking group, viz. the p-toluoyl group. The linking reactions were based on the formation of amides or esters by the reaction of an acid chloride system with an amine or alcohol. Phase II involved the synthesis of bis-chain ligand systems and their attachment onto the p-toluoyl linking group. A further linking group was also developed at this stage, viz. the xylyl group. In the preparation of phase II ligand systems, use was made of malonic ester and iminodiacetic acid derivatives. Phase III has involved the synthesis of cyclic ligand systems, with skeletons based upon the structures used in phase I and phase II and two crown ether type systems have been prepared.
- Full Text:
- Date Issued: 1992
The evaluation of indomethacin and theophylline oral controlled/modified-release dosage forms in vitro-in vivo correlations
- Tandt, Ludo Alfons Germaan Luc
- Authors: Tandt, Ludo Alfons Germaan Luc
- Date: 1992
- Subjects: Theophylline , Indomethacin , Drugs -- Controlled release , Drugs -- Dosage forms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3794 , http://hdl.handle.net/10962/d1003272 , Theophylline , Indomethacin , Drugs -- Controlled release , Drugs -- Dosage forms
- Description: Over the past few decades many researchers have investigated the utility of in vitro - in vivo correlations for the assessment of dosage forms. These investigations are, however, dependent on reproducible dissolution data and well conducted biostudies in order to establish meaningful and robust correlations. Despite the fact that the establishment of such correlations is perhaps idealistic, considerable interest has still been shown in this area of research. Various Controlled/Modified Release Dosage Forms (CMRD's) of theophylline, a weakly basic drug, and indomethacin, a weakly acidic drug, were assessed in order to establish in vitro - in vivo correlations. Dissolution rate studies were carried out using either the USP basket or paddle apparatus. The dissolution rate studies were conducted in a range of dissolution media of varying pH. Bioavailability studies were conducted on the dosage forms used by the Biopharmaceutics Research Institute at Rhodes University. The results of these biostudies were kindly made available for use in this research project. Type A correlations were established using a mathematical simulation process whereby expected in vivo responses are simulated and compared to actual profiles obtained for the dosage forms. In order to perform the simulations the dissolution rate profiles were stripped and using linear regression and the methods of residuals the dissolution rate order and the relevant dissolution rates were obtained. The results of the s imulations indicated that the in vivo serum concentration-time curves could be accurately predicted for the theophylline dosage forms but to a lesser extent, for the indomethacin formulations. The dissolution rate studies indicated that the paddle method is a suitable method for dissolution rate studies of theophylline CMRD's, although it appeared that the optimum pH of the dissolution medium was formulation dependent. Dissolution rate studies conducted on indomethacin formulations indicated that the USP specified basket method for extended-release indomethacin formulations was not able to distinguish between two formulations which exhibited different in vivo profiles. The conversion to the paddle method was, however, able to highlight the differences between these formulations. The use of three dimensional topographs to depict dissolution rate profiles was demonstrated for formulations of both theophylline and indomethacin. The topographs enabled the successful differentiation between bioinequivalent formulations. The dissolution rate profiles were also fitted to the Wei bull equation and the parameters obtained from this were compared to the Weibull parameters obtained from the in vivo absorption plots obtained using the Wagner-Nelson method. The results indicated that the Weibull function was suitable to describe both the in vivo and in vitro data. The following recommendations for the preformulation dissolution studies of weakly acidic and weakly basic drugs are proposed. The dissolution rate studies of weakly acid drugs, such as indomethacin, should be carried out over a range of pH utilising the paddle apparatus. Three dimensional topographs based on the dissolution data should be constructed and used as a comparative tool for different formulations. Based on these comparisons the appropriate formulation can then be selected for a pilot scale in vivo bioavailability study. The dissolution rate studies of weakly basic drugs, such as theophylline, should be carried out over a range of pH utilising the paddle apparatus. The dissolution data should then be used to simulate the expected in vivo profile and on this basis the appropriate formulation selected for a pilot scale bioavailability study. The above approach to the preformulation studies of new CMRO's would allow for the more careful selection of new dosage forms and could thus eliminate costly and unnecessary bioavailability studies performed on inferior formulations.
- Full Text:
- Date Issued: 1992
- Authors: Tandt, Ludo Alfons Germaan Luc
- Date: 1992
- Subjects: Theophylline , Indomethacin , Drugs -- Controlled release , Drugs -- Dosage forms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3794 , http://hdl.handle.net/10962/d1003272 , Theophylline , Indomethacin , Drugs -- Controlled release , Drugs -- Dosage forms
- Description: Over the past few decades many researchers have investigated the utility of in vitro - in vivo correlations for the assessment of dosage forms. These investigations are, however, dependent on reproducible dissolution data and well conducted biostudies in order to establish meaningful and robust correlations. Despite the fact that the establishment of such correlations is perhaps idealistic, considerable interest has still been shown in this area of research. Various Controlled/Modified Release Dosage Forms (CMRD's) of theophylline, a weakly basic drug, and indomethacin, a weakly acidic drug, were assessed in order to establish in vitro - in vivo correlations. Dissolution rate studies were carried out using either the USP basket or paddle apparatus. The dissolution rate studies were conducted in a range of dissolution media of varying pH. Bioavailability studies were conducted on the dosage forms used by the Biopharmaceutics Research Institute at Rhodes University. The results of these biostudies were kindly made available for use in this research project. Type A correlations were established using a mathematical simulation process whereby expected in vivo responses are simulated and compared to actual profiles obtained for the dosage forms. In order to perform the simulations the dissolution rate profiles were stripped and using linear regression and the methods of residuals the dissolution rate order and the relevant dissolution rates were obtained. The results of the s imulations indicated that the in vivo serum concentration-time curves could be accurately predicted for the theophylline dosage forms but to a lesser extent, for the indomethacin formulations. The dissolution rate studies indicated that the paddle method is a suitable method for dissolution rate studies of theophylline CMRD's, although it appeared that the optimum pH of the dissolution medium was formulation dependent. Dissolution rate studies conducted on indomethacin formulations indicated that the USP specified basket method for extended-release indomethacin formulations was not able to distinguish between two formulations which exhibited different in vivo profiles. The conversion to the paddle method was, however, able to highlight the differences between these formulations. The use of three dimensional topographs to depict dissolution rate profiles was demonstrated for formulations of both theophylline and indomethacin. The topographs enabled the successful differentiation between bioinequivalent formulations. The dissolution rate profiles were also fitted to the Wei bull equation and the parameters obtained from this were compared to the Weibull parameters obtained from the in vivo absorption plots obtained using the Wagner-Nelson method. The results indicated that the Weibull function was suitable to describe both the in vivo and in vitro data. The following recommendations for the preformulation dissolution studies of weakly acidic and weakly basic drugs are proposed. The dissolution rate studies of weakly acid drugs, such as indomethacin, should be carried out over a range of pH utilising the paddle apparatus. Three dimensional topographs based on the dissolution data should be constructed and used as a comparative tool for different formulations. Based on these comparisons the appropriate formulation can then be selected for a pilot scale in vivo bioavailability study. The dissolution rate studies of weakly basic drugs, such as theophylline, should be carried out over a range of pH utilising the paddle apparatus. The dissolution data should then be used to simulate the expected in vivo profile and on this basis the appropriate formulation selected for a pilot scale bioavailability study. The above approach to the preformulation studies of new CMRO's would allow for the more careful selection of new dosage forms and could thus eliminate costly and unnecessary bioavailability studies performed on inferior formulations.
- Full Text:
- Date Issued: 1992
The chemistry of a new water-recirculation aquaculture system with emphasis on the influence of ozone on water quality
- Authors: Stobart, Michael David
- Date: 1992
- Subjects: Water quality -- Environmental aspects -- Testing , Ozone -- Physiological effect , Aquatic ecology , Aquaculture
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5244 , http://hdl.handle.net/10962/d1005087 , Water quality -- Environmental aspects -- Testing , Ozone -- Physiological effect , Aquatic ecology , Aquaculture
- Description: Water quality changes that occur during establishment and maintenance of nitrification in two identical recirculating aquaculture systems containing rainbow trout are described. The time taken for the nitrification process to become established was 40-45 days. Mortality of fish attributed to elevated nitrite concentrations were recorded during the initial conditioning phase of the systems. Un-ionised ammonia concentrations did not attain lethal levels during this period. Nitrate concentrations accumulated slowly throughout the study, while the pH and alkalinity of the water decreased with progressive nitrification. Levels of carbon dioxide, calcium, dissolved and suspended solids remained relatively stable until the carrying capacity of the systems was increased, upon which they increased rapidly and general water quality deteriorated. Permanently elevated concentrations of ammonia and nitrite served as an indication that the carrying capacity of the systems had been exceeded. The use of ozone as a water enhancement treatment in aquaculture systems during one- and six-hour applications was also considered in this study. Ozonation significantly reduced nitrite levels at · low concentrations (0,1 - 0,15 mg/l), although they returned to pre-treatment levels within a few hours of cessation of the treatment. The formation of an unstable, intermediate product that reforms as nitrite in the absence of ozone, rather than the complete oxidation of nitrite to nitrate, is proposed. Ozonation also resulted in decreased dissolved solids, and improved the clarity and odour of the water. Ozone had no effect on ammonia concentrations (at pH > 7,0), or on nitrate or calcium levels, and did not conclusively increase the redox potential of the water. Residual ozone concentrations up to 0,04 mg/l in a sixhour treatment had no harmful effects on rainbow trout, and there were no signs of gas-bubble disease arising from supersaturation of the water with oxygen. Activated carbon filters were effective at removing residual ozone from the water after treatment. Treatment of the water with oxygen alone had no effect on nitrite concentrations.
- Full Text:
- Date Issued: 1992
- Authors: Stobart, Michael David
- Date: 1992
- Subjects: Water quality -- Environmental aspects -- Testing , Ozone -- Physiological effect , Aquatic ecology , Aquaculture
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5244 , http://hdl.handle.net/10962/d1005087 , Water quality -- Environmental aspects -- Testing , Ozone -- Physiological effect , Aquatic ecology , Aquaculture
- Description: Water quality changes that occur during establishment and maintenance of nitrification in two identical recirculating aquaculture systems containing rainbow trout are described. The time taken for the nitrification process to become established was 40-45 days. Mortality of fish attributed to elevated nitrite concentrations were recorded during the initial conditioning phase of the systems. Un-ionised ammonia concentrations did not attain lethal levels during this period. Nitrate concentrations accumulated slowly throughout the study, while the pH and alkalinity of the water decreased with progressive nitrification. Levels of carbon dioxide, calcium, dissolved and suspended solids remained relatively stable until the carrying capacity of the systems was increased, upon which they increased rapidly and general water quality deteriorated. Permanently elevated concentrations of ammonia and nitrite served as an indication that the carrying capacity of the systems had been exceeded. The use of ozone as a water enhancement treatment in aquaculture systems during one- and six-hour applications was also considered in this study. Ozonation significantly reduced nitrite levels at · low concentrations (0,1 - 0,15 mg/l), although they returned to pre-treatment levels within a few hours of cessation of the treatment. The formation of an unstable, intermediate product that reforms as nitrite in the absence of ozone, rather than the complete oxidation of nitrite to nitrate, is proposed. Ozonation also resulted in decreased dissolved solids, and improved the clarity and odour of the water. Ozone had no effect on ammonia concentrations (at pH > 7,0), or on nitrate or calcium levels, and did not conclusively increase the redox potential of the water. Residual ozone concentrations up to 0,04 mg/l in a sixhour treatment had no harmful effects on rainbow trout, and there were no signs of gas-bubble disease arising from supersaturation of the water with oxygen. Activated carbon filters were effective at removing residual ozone from the water after treatment. Treatment of the water with oxygen alone had no effect on nitrite concentrations.
- Full Text:
- Date Issued: 1992
The "Big E": the English (first language) endorsement on the teacher's bilingualism certificate: an investigation into the background to and origin of this requirement, an evaluation of past and current examining practices and standards and criteria, a needs assessment, and suggestions and recommendations for sound practice
- Authors: Spingies, Conrad
- Date: 1992
- Subjects: Teachers -- Training of -- South Africa Teachers -- Selection and appointment Teachers -- Language Teachers -- Certification -- South Africa Bilingualism -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1427 , http://hdl.handle.net/10962/d1003308
- Description: South African education authorities demand of teachers a high degree of competency in both official languages. In the Cape Province in particular, teachers are not considered eligible for promotion posts unless they possess the so-called Higher Bilingualism Certificate, signifying their command of both official languages at "First Language" level. In view of the fact that the overwhelming majority of schools nowadays are single-medium institutions; this requirement may strike the objective observer as an anomaly. An attempt was made, therefore, first of all to investigate the historical background to this requirement. The "language question", a problematic feature of South African education since the beginning of the nineteenth.century, was not resolved when legislators chose "bilingualism and language equality" for the Union of South Africa in 1910. The available evidence suggests, however, that bilingualism was actively pursued as an educational ideal at least until the end of the 1940s, and for this reason education authorities placed a high premium on teachers who were "fully bilingual". Nowadays the typical (White) school is a single-medium institution where the second language is rarely if ever heard outside the classroom where it is taught as a subject. The present policy, to demand a high degree of proficiency in both official languages of teachers occupying promotion posts at such a school, may then be described not only as an anomaly, but as an anachronism. A further problem is the fact that the various educational institutions (specifically teachers' colleges and universities) that set examinations leading to the Higher Bilingualism Certificate rarely communicate with one another, and are therefore unable to agree on uniform standards and criteria, or to ensure that such standards are maintained. That this is indeed the case, was confirmed by examination of "Big E" test papers set at three teachers' colleges, two Colleges for Continued Training, and four universities in the Cape Province. In an attempt to establish what assistance and support might be needed by a "second language" user of English in order for him to improve to the point where he resembled a "first language" user of English in his "terminal language behaviour", a comparison (by means of error analysis) of the responses of two groups (an Ll and an L2 group) to the same test paper was undertaken. The available evidence suggests that L2 users may need to be helped to acquire a more extensive vocabulary, but, above all, that they need to improve their ability to handle two crucially important aspects of usage: idiom and grammar. The final chapter attempts to establish pedagogic and linguistic bases for a course intended for "Big E" candidates, and makes recommendations with regard to (i) the content and the form of the course, and (ii) sound examination practice. The concluding thoughts offer the view that such a course could remain useful even in a future South Africa where the emphasis may shift from a demand for teachers who are "fully bilingual" to teachers who have a good command of English.
- Full Text:
- Date Issued: 1992
- Authors: Spingies, Conrad
- Date: 1992
- Subjects: Teachers -- Training of -- South Africa Teachers -- Selection and appointment Teachers -- Language Teachers -- Certification -- South Africa Bilingualism -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1427 , http://hdl.handle.net/10962/d1003308
- Description: South African education authorities demand of teachers a high degree of competency in both official languages. In the Cape Province in particular, teachers are not considered eligible for promotion posts unless they possess the so-called Higher Bilingualism Certificate, signifying their command of both official languages at "First Language" level. In view of the fact that the overwhelming majority of schools nowadays are single-medium institutions; this requirement may strike the objective observer as an anomaly. An attempt was made, therefore, first of all to investigate the historical background to this requirement. The "language question", a problematic feature of South African education since the beginning of the nineteenth.century, was not resolved when legislators chose "bilingualism and language equality" for the Union of South Africa in 1910. The available evidence suggests, however, that bilingualism was actively pursued as an educational ideal at least until the end of the 1940s, and for this reason education authorities placed a high premium on teachers who were "fully bilingual". Nowadays the typical (White) school is a single-medium institution where the second language is rarely if ever heard outside the classroom where it is taught as a subject. The present policy, to demand a high degree of proficiency in both official languages of teachers occupying promotion posts at such a school, may then be described not only as an anomaly, but as an anachronism. A further problem is the fact that the various educational institutions (specifically teachers' colleges and universities) that set examinations leading to the Higher Bilingualism Certificate rarely communicate with one another, and are therefore unable to agree on uniform standards and criteria, or to ensure that such standards are maintained. That this is indeed the case, was confirmed by examination of "Big E" test papers set at three teachers' colleges, two Colleges for Continued Training, and four universities in the Cape Province. In an attempt to establish what assistance and support might be needed by a "second language" user of English in order for him to improve to the point where he resembled a "first language" user of English in his "terminal language behaviour", a comparison (by means of error analysis) of the responses of two groups (an Ll and an L2 group) to the same test paper was undertaken. The available evidence suggests that L2 users may need to be helped to acquire a more extensive vocabulary, but, above all, that they need to improve their ability to handle two crucially important aspects of usage: idiom and grammar. The final chapter attempts to establish pedagogic and linguistic bases for a course intended for "Big E" candidates, and makes recommendations with regard to (i) the content and the form of the course, and (ii) sound examination practice. The concluding thoughts offer the view that such a course could remain useful even in a future South Africa where the emphasis may shift from a demand for teachers who are "fully bilingual" to teachers who have a good command of English.
- Full Text:
- Date Issued: 1992
The anatomy and ecophysiology of Mariscus congestus from three different habitats in the Albany and Bathurst districts of the Eastern Cape, investigated under field and laboratory conditions
- Authors: Sonnenberg, Bernd Jürgen
- Date: 1992
- Subjects: Cyperaceae -- South Africa , Plant anatomy , Plant physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4229 , http://hdl.handle.net/10962/d1003798 , Cyperaceae -- South Africa , Plant anatomy , Plant physiology
- Description: An investigation of the anatomy and gas exchange characteristics of Mariscus congestus in three different habitats was undertaken in order to establish whether M. congestus from the three different habitats displayed any ecotypic responses when placed in a new similar environment. It was hoped that the results of this investigation would yield evidence that would support the ecotype concept similar to the investigations of Milner and Hiesey (1964), Green (1969) and Slayter and Ferrar (1977). On the basis of the site leaf anatomy, M. congestus investigated at the coast (site 1) differed in many respects from the inland plants (sites 2 and 3). These differences suggest that the coastal plants may have undergone a slight ecotypic divergence from the inland plants. The anatomical investigation also suggested that the leaves of M. congestus from all three sites may either be C₄ NADP-ME or PCK and that all had typical Chlorocyperiod anatomy. The habitat microclimates at sites 1-3 had different light and water regimes. There were no significant differences between the 12 month temperature environments of the three sites. There was however, a minor difference between the coastal (high temperature) and the inland (lower temperature) sites. M. congestus at the three sites had significantly different CO₂ assimilation rates, transpiration and stomatal conductance in response to the differing habitat microclimates. The water use efficiency of the sites were however, similar. Site 1 attained the highest CO₂ assimilation rates, transpiration, stomatal conductance, and water use efficiency and site 3 the lowest. Under similar conditions the gas exchange data for the potted plants indicated that M. congestus from the different sites was typically C₄. The optimal photosynthetic temperatures of all the sites was above 30°C and they did not show significant inhibition of CO₂ assimilation by different oxygen concentrations. The results of the laboratory investigation of the potted plants suggested that the only site-specific (ecotypic) response of M. eongestus was the light intensity at which the plants from the different sites were light saturated. The light and temperature response of field plants under field conditions was not comparable to the light and temperature response of potted plants under laboratory conditions. This may have been due to the field results being obtained under differing water and soil nutrient regimes. The potted plants may also have had a reduced root mass compared to their field counterparts and the potted plants may have also have become root bound. Under field conditions the plants had differing light saturation points and optimal photosynthetic temperatures compared to the potted plants. This investigation thus did not support the hypothesis stated in this thesis. The data in this investigation thus may indicate that plants with as diverse habitats as Mariscus congestus that are removed from their natural habitats display rapid changes in gas exchange characteristics in response to their new microclimates, with few ecotypic physiological characteristics of the old habitat being retained.
- Full Text:
- Date Issued: 1992
- Authors: Sonnenberg, Bernd Jürgen
- Date: 1992
- Subjects: Cyperaceae -- South Africa , Plant anatomy , Plant physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4229 , http://hdl.handle.net/10962/d1003798 , Cyperaceae -- South Africa , Plant anatomy , Plant physiology
- Description: An investigation of the anatomy and gas exchange characteristics of Mariscus congestus in three different habitats was undertaken in order to establish whether M. congestus from the three different habitats displayed any ecotypic responses when placed in a new similar environment. It was hoped that the results of this investigation would yield evidence that would support the ecotype concept similar to the investigations of Milner and Hiesey (1964), Green (1969) and Slayter and Ferrar (1977). On the basis of the site leaf anatomy, M. congestus investigated at the coast (site 1) differed in many respects from the inland plants (sites 2 and 3). These differences suggest that the coastal plants may have undergone a slight ecotypic divergence from the inland plants. The anatomical investigation also suggested that the leaves of M. congestus from all three sites may either be C₄ NADP-ME or PCK and that all had typical Chlorocyperiod anatomy. The habitat microclimates at sites 1-3 had different light and water regimes. There were no significant differences between the 12 month temperature environments of the three sites. There was however, a minor difference between the coastal (high temperature) and the inland (lower temperature) sites. M. congestus at the three sites had significantly different CO₂ assimilation rates, transpiration and stomatal conductance in response to the differing habitat microclimates. The water use efficiency of the sites were however, similar. Site 1 attained the highest CO₂ assimilation rates, transpiration, stomatal conductance, and water use efficiency and site 3 the lowest. Under similar conditions the gas exchange data for the potted plants indicated that M. congestus from the different sites was typically C₄. The optimal photosynthetic temperatures of all the sites was above 30°C and they did not show significant inhibition of CO₂ assimilation by different oxygen concentrations. The results of the laboratory investigation of the potted plants suggested that the only site-specific (ecotypic) response of M. eongestus was the light intensity at which the plants from the different sites were light saturated. The light and temperature response of field plants under field conditions was not comparable to the light and temperature response of potted plants under laboratory conditions. This may have been due to the field results being obtained under differing water and soil nutrient regimes. The potted plants may also have had a reduced root mass compared to their field counterparts and the potted plants may have also have become root bound. Under field conditions the plants had differing light saturation points and optimal photosynthetic temperatures compared to the potted plants. This investigation thus did not support the hypothesis stated in this thesis. The data in this investigation thus may indicate that plants with as diverse habitats as Mariscus congestus that are removed from their natural habitats display rapid changes in gas exchange characteristics in response to their new microclimates, with few ecotypic physiological characteristics of the old habitat being retained.
- Full Text:
- Date Issued: 1992
Environmentalism and its implications for education: a study of private schools in the Eastern Cape
- Authors: Slade, Wilfred John
- Date: 1992
- Subjects: Environmental education -- Study and teaching -- South Africa Environmental education -- Curricula -- South Africa Private schools -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1520 , http://hdl.handle.net/10962/d1003402
- Description: This study explores the extent to which the ethos and the basic approach to education taken by three Eastern Cape private schools influences the practice of environmental education within these schools. Their environmental education programmes are evaluated in terms of the guiding principles adopted by the international community in the 'Tbilisi Principles of Environmental Education'. An ethnographic approach was adopted for this research and findings are essentially descriptive and qualitative, with special regard to social structures and the attitudes of individuals within these structures.
- Full Text:
- Date Issued: 1992
- Authors: Slade, Wilfred John
- Date: 1992
- Subjects: Environmental education -- Study and teaching -- South Africa Environmental education -- Curricula -- South Africa Private schools -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1520 , http://hdl.handle.net/10962/d1003402
- Description: This study explores the extent to which the ethos and the basic approach to education taken by three Eastern Cape private schools influences the practice of environmental education within these schools. Their environmental education programmes are evaluated in terms of the guiding principles adopted by the international community in the 'Tbilisi Principles of Environmental Education'. An ethnographic approach was adopted for this research and findings are essentially descriptive and qualitative, with special regard to social structures and the attitudes of individuals within these structures.
- Full Text:
- Date Issued: 1992
Phase equilibria in three component systems alcohol-hydrocarbon-water
- Authors: Siswana, Msimelelo Patrick
- Date: 1992
- Subjects: Chemical equilibrium , Liquid-liquid equilibrium , Alcohol as fuel , Hydrocarbons , Water chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4327 , http://hdl.handle.net/10962/d1004988 , Chemical equilibrium , Liquid-liquid equilibrium , Alcohol as fuel , Hydrocarbons , Water chemistry
- Description: The fuel industry in many parts of the world is blending alcohols with motor fuel either to extend the fuel or to improve its octane rating or both. Unfortunately alcohols are hygroscopic and as a result, water becomes a component of the fuel. This can lead to phase separation and the formation of a water-rich layer which could have serious corrosion consequences. In an attempt to understand the phase-splitting in alcohol-petrol-water blends, phase equilibria in ternary systems (alcohol-hydrocarbon-water) have been determined by experiment. The phase equilibria in these ternary systems are also discussed in terms of modern theories of liquid mixtures and the UNIQUAC theory is applied to the "ethanol + benzene + water" ternary system. The alcohols are all the C₁, C₂, C₃ and C₄ alcohols, and the hydrocarbons include those typically found in petrol, e.g. cyclohexane, benzene and substituted benzenes.
- Full Text:
- Date Issued: 1992
- Authors: Siswana, Msimelelo Patrick
- Date: 1992
- Subjects: Chemical equilibrium , Liquid-liquid equilibrium , Alcohol as fuel , Hydrocarbons , Water chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4327 , http://hdl.handle.net/10962/d1004988 , Chemical equilibrium , Liquid-liquid equilibrium , Alcohol as fuel , Hydrocarbons , Water chemistry
- Description: The fuel industry in many parts of the world is blending alcohols with motor fuel either to extend the fuel or to improve its octane rating or both. Unfortunately alcohols are hygroscopic and as a result, water becomes a component of the fuel. This can lead to phase separation and the formation of a water-rich layer which could have serious corrosion consequences. In an attempt to understand the phase-splitting in alcohol-petrol-water blends, phase equilibria in ternary systems (alcohol-hydrocarbon-water) have been determined by experiment. The phase equilibria in these ternary systems are also discussed in terms of modern theories of liquid mixtures and the UNIQUAC theory is applied to the "ethanol + benzene + water" ternary system. The alcohols are all the C₁, C₂, C₃ and C₄ alcohols, and the hydrocarbons include those typically found in petrol, e.g. cyclohexane, benzene and substituted benzenes.
- Full Text:
- Date Issued: 1992
Environmental education in primary schools in Bophuthatswana : a case study in curriculum implementation
- Authors: Shongwe, Doctor Petrus
- Date: 1992
- Subjects: Environmental education -- South Africa -- Bophuthatswana , Primary school teaching -- Research -- South Africa -- Bophuthatswana
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1514 , http://hdl.handle.net/10962/d1003396
- Description: This study examines the extent to which teachers in Senior Primary Schools who have obtained a professional qualification in Environmental Education, implement Environmental Education in their schools. It also explores factors which influence the implementation of Environmental Education at the Senior Primary School. Teachers who had qualified from Tlhabane and Hebron Colleges of Education were interviewed as were the principals of their schools and some of the lecturers who had taught them Environmental Education. The implementation of Environmental Education was addressed by means of comparing the teacher's responses with Primary Environmental Education Teacher Competencies as suggested by Glasgow and Robinson (1986) and Lahiry et al (1988). The information was deduced from the teachers responses from semi-structured interviews and were qualitatively analysed.
- Full Text:
- Date Issued: 1992
- Authors: Shongwe, Doctor Petrus
- Date: 1992
- Subjects: Environmental education -- South Africa -- Bophuthatswana , Primary school teaching -- Research -- South Africa -- Bophuthatswana
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1514 , http://hdl.handle.net/10962/d1003396
- Description: This study examines the extent to which teachers in Senior Primary Schools who have obtained a professional qualification in Environmental Education, implement Environmental Education in their schools. It also explores factors which influence the implementation of Environmental Education at the Senior Primary School. Teachers who had qualified from Tlhabane and Hebron Colleges of Education were interviewed as were the principals of their schools and some of the lecturers who had taught them Environmental Education. The implementation of Environmental Education was addressed by means of comparing the teacher's responses with Primary Environmental Education Teacher Competencies as suggested by Glasgow and Robinson (1986) and Lahiry et al (1988). The information was deduced from the teachers responses from semi-structured interviews and were qualitatively analysed.
- Full Text:
- Date Issued: 1992