The natural history of the humpback dolphin, Sousa chinensis, in KwaZulu-Natal, South Africa : age, growth and reproduction
- Authors: Nolte, Zianca
- Date: 2014
- Subjects: Sousa -- South Africa -- KwaZulu-Natal , Dolphins -- Behavior -- South Africa -- KwaZulu-Natal , Dolphins -- Age determination -- South Africa -- KwaZulu-Natal , Dolphins -- Development -- South Africa -- KwaZulu-Natal , Dolphins -- South Africa -- KwaZulu-Natal -- Reproduction , Dolphins -- Physiology -- South Africa -- KwaZulu-Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5878 , http://hdl.handle.net/10962/d1013178
- Description: Globally, inshore cetaceans are being threatened by a number of anthropogenic activities. The Indo-Pacific humpback dolphin, Sousa chinensis, is currently listed as ‘near threatened’ by the International Union for the Conservation of Nature (IUCN). In order to be able to advise on management and conservation strategies, knowledge on the life history of the species is required. To date very little is known about the biology of humpback dolphins. The aim of the present study was to determine basic life history parameters, including age, growth and reproduction of humpback dolphins incidentally caught in shark nets. Age was estimated by counting the growth layer groups (GLGs) in the dentine and cementum of sectioned and stained teeth. Both a Von Bertalanffy and a Gompertz growth curve fitted well to the data, but for comparison with previous studies on Sousa, the Gompertz growth function was adopted to describe the relationship between length and age for KwaZulu-Natal populations. Length at birth was estimated between 104.33 and 111.57 cm for males and females, respectively. Asymptotic length was reached at 266.48 cm and 239.29 cm for males and females, respectively. This corresponds to the attainment of physical maturity at 24 GLGs in males and 16 GLGs in females. Asymptotic mass for males could not be determined, while for females it occurred around 160 kg. The maximum age estimates and recorded lengths were 24 GLGs and 279 cm for males and 17.7 GLGs and 249 cm for females. Differences in length-at-age and mass-at-age for S. chinensis suggest sexual dimorphism. The attainment of sexual maturity in males occurred between 9 and 10 GLGs, corresponding to 230 cm total body length and 140 kg. The maximum combined testis mass of mature males comprised 0.42% of total body mass, and a roving male mating system was proposed. In females, sexual maturity occurred around 7.6 GLG, between 220 and 222 cm and 104 - 140 kg. The ovulation rate is estimated at 0.2 ovulations per annum, suggesting a calving interval of five years. It is evident from the results obtained in the present study that geographical differences exist in the life history parameters of S. chinensis. As a result, regional conservation and management strategies are imperative. Results from this study can therefore assist in assessing the status of existing population structures in the KwaZulu-Natal coastal waters, and the implementation of regional mitigation strategies to ensure the continued survival of humpback dolphins in the region.
- Full Text:
- Date Issued: 2014
- Authors: Nolte, Zianca
- Date: 2014
- Subjects: Sousa -- South Africa -- KwaZulu-Natal , Dolphins -- Behavior -- South Africa -- KwaZulu-Natal , Dolphins -- Age determination -- South Africa -- KwaZulu-Natal , Dolphins -- Development -- South Africa -- KwaZulu-Natal , Dolphins -- South Africa -- KwaZulu-Natal -- Reproduction , Dolphins -- Physiology -- South Africa -- KwaZulu-Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5878 , http://hdl.handle.net/10962/d1013178
- Description: Globally, inshore cetaceans are being threatened by a number of anthropogenic activities. The Indo-Pacific humpback dolphin, Sousa chinensis, is currently listed as ‘near threatened’ by the International Union for the Conservation of Nature (IUCN). In order to be able to advise on management and conservation strategies, knowledge on the life history of the species is required. To date very little is known about the biology of humpback dolphins. The aim of the present study was to determine basic life history parameters, including age, growth and reproduction of humpback dolphins incidentally caught in shark nets. Age was estimated by counting the growth layer groups (GLGs) in the dentine and cementum of sectioned and stained teeth. Both a Von Bertalanffy and a Gompertz growth curve fitted well to the data, but for comparison with previous studies on Sousa, the Gompertz growth function was adopted to describe the relationship between length and age for KwaZulu-Natal populations. Length at birth was estimated between 104.33 and 111.57 cm for males and females, respectively. Asymptotic length was reached at 266.48 cm and 239.29 cm for males and females, respectively. This corresponds to the attainment of physical maturity at 24 GLGs in males and 16 GLGs in females. Asymptotic mass for males could not be determined, while for females it occurred around 160 kg. The maximum age estimates and recorded lengths were 24 GLGs and 279 cm for males and 17.7 GLGs and 249 cm for females. Differences in length-at-age and mass-at-age for S. chinensis suggest sexual dimorphism. The attainment of sexual maturity in males occurred between 9 and 10 GLGs, corresponding to 230 cm total body length and 140 kg. The maximum combined testis mass of mature males comprised 0.42% of total body mass, and a roving male mating system was proposed. In females, sexual maturity occurred around 7.6 GLG, between 220 and 222 cm and 104 - 140 kg. The ovulation rate is estimated at 0.2 ovulations per annum, suggesting a calving interval of five years. It is evident from the results obtained in the present study that geographical differences exist in the life history parameters of S. chinensis. As a result, regional conservation and management strategies are imperative. Results from this study can therefore assist in assessing the status of existing population structures in the KwaZulu-Natal coastal waters, and the implementation of regional mitigation strategies to ensure the continued survival of humpback dolphins in the region.
- Full Text:
- Date Issued: 2014
Musculoskeletal and perceptual responses of batsmen comparing high- and moderate-volume sprints between the wickets
- Authors: Sheppard, Bronwyn Jane
- Date: 2012
- Subjects: Cricket -- Batting -- Physiological aspects , Cricket injuries , Musculoskeletal system -- Wounds and injuries
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5171 , http://hdl.handle.net/10962/d1016366
- Description: Background: Literature has associated repeated eccentric muscle actions with increased muscle damage of the muscles involved. Eccentric actions are typical in sports which are ‘stop-start’ in nature requiring rapid acceleration and deceleration, typical of a batting activity in cricket. Ultra-structural damage of the skeletal muscle as a consequence of repeated decelerating activities is associated with performance decrements, particularly muscle strength and sprinting speeds. This suggests that eccentric strength decrements may provide an indication for the development of muscle strain injuries during these activities. Despite these findings, limited research has identified the specific musculoskeletal demands placed on cricket batsmen, particularly with reference to various match intensities. Objective: The present study, therefore, sought to determine the specific musculoskeletal, physiological and perceptual demands placed on specialised batsmen during two work bouts of different intensities; one representing a highintensity work bout and the other a moderate-intensity work bout. The dependent variables of interest were muscle activation, isokinetic strength changes, heart rate, ‘central’ and ‘local’ ratings of perceived exertion (RPE), body discomfort and performance. Methods: The two experimental conditions, representative of a high- (HVR) and moderate-volume running (MVR) batting protocol, required players to perform a simulated batting work bout of either twelve or six runs an over, within a laboratory setting. Selected physiological, perceptual and performance measures were collected at specific time intervals throughout the work bout while the biophysical measures were collected prior to, and following both protocols. Results: Of the variables measured, heart rate, ‘central’ and ‘local’ RPE values were observed to increase significantly (p<0.05) over time. This increase was greater as a consequence of the HVR in comparison to the MVR. No change in sprint times was documented during the MVR, in contrast, significant (p<0.05) increases over time were observed during the HVR, further highlighting the elevated demands associated with this condition. In addition, an ‘end spurt’ was observed particularly following the HVR condition, suggesting athletes were conserving themselves through the adoption of a pacing strategy. Reductions in biceps femoris and semitendinosus muscle activation levels were observed following the HVR. This was further supported by the significantly greater levels of semitendinosus activation following the MVR when compared to the HVR. Peak concentric and eccentric knee extensor (EXT) (-17.17% and -16.07% respectively) and eccentric flexor (FLEX) (- 17.49%) values decreased significantly (p<0.05) following the HVR at 60°.s-1. In addition, concentric and eccentric total work produced by the flexors and eccentric extensors resulted in significantly (p<0.05) lower values due to the HVR. Conclusion: The intermittent high-volume batting work bout elicited elevated mean heart rates, perceived ratings of cardiovascular and muscular effort and sprint times. Furthermore, hamstring activation levels and muscle strength, particularly concentric strength of the dominant lower limb were negatively affected by the HVR condition. These results suggest elevated demands were placed on the hamstring musculature as a consequence of the HVR condition, indicating a greater degree of musculoskeletal strain and increased injury risk associated with running between the wickets at this intensity, representative of an aggressive batting scenario.
- Full Text:
- Date Issued: 2012
- Authors: Sheppard, Bronwyn Jane
- Date: 2012
- Subjects: Cricket -- Batting -- Physiological aspects , Cricket injuries , Musculoskeletal system -- Wounds and injuries
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5171 , http://hdl.handle.net/10962/d1016366
- Description: Background: Literature has associated repeated eccentric muscle actions with increased muscle damage of the muscles involved. Eccentric actions are typical in sports which are ‘stop-start’ in nature requiring rapid acceleration and deceleration, typical of a batting activity in cricket. Ultra-structural damage of the skeletal muscle as a consequence of repeated decelerating activities is associated with performance decrements, particularly muscle strength and sprinting speeds. This suggests that eccentric strength decrements may provide an indication for the development of muscle strain injuries during these activities. Despite these findings, limited research has identified the specific musculoskeletal demands placed on cricket batsmen, particularly with reference to various match intensities. Objective: The present study, therefore, sought to determine the specific musculoskeletal, physiological and perceptual demands placed on specialised batsmen during two work bouts of different intensities; one representing a highintensity work bout and the other a moderate-intensity work bout. The dependent variables of interest were muscle activation, isokinetic strength changes, heart rate, ‘central’ and ‘local’ ratings of perceived exertion (RPE), body discomfort and performance. Methods: The two experimental conditions, representative of a high- (HVR) and moderate-volume running (MVR) batting protocol, required players to perform a simulated batting work bout of either twelve or six runs an over, within a laboratory setting. Selected physiological, perceptual and performance measures were collected at specific time intervals throughout the work bout while the biophysical measures were collected prior to, and following both protocols. Results: Of the variables measured, heart rate, ‘central’ and ‘local’ RPE values were observed to increase significantly (p<0.05) over time. This increase was greater as a consequence of the HVR in comparison to the MVR. No change in sprint times was documented during the MVR, in contrast, significant (p<0.05) increases over time were observed during the HVR, further highlighting the elevated demands associated with this condition. In addition, an ‘end spurt’ was observed particularly following the HVR condition, suggesting athletes were conserving themselves through the adoption of a pacing strategy. Reductions in biceps femoris and semitendinosus muscle activation levels were observed following the HVR. This was further supported by the significantly greater levels of semitendinosus activation following the MVR when compared to the HVR. Peak concentric and eccentric knee extensor (EXT) (-17.17% and -16.07% respectively) and eccentric flexor (FLEX) (- 17.49%) values decreased significantly (p<0.05) following the HVR at 60°.s-1. In addition, concentric and eccentric total work produced by the flexors and eccentric extensors resulted in significantly (p<0.05) lower values due to the HVR. Conclusion: The intermittent high-volume batting work bout elicited elevated mean heart rates, perceived ratings of cardiovascular and muscular effort and sprint times. Furthermore, hamstring activation levels and muscle strength, particularly concentric strength of the dominant lower limb were negatively affected by the HVR condition. These results suggest elevated demands were placed on the hamstring musculature as a consequence of the HVR condition, indicating a greater degree of musculoskeletal strain and increased injury risk associated with running between the wickets at this intensity, representative of an aggressive batting scenario.
- Full Text:
- Date Issued: 2012
The development of a WAIS-III short form for use in South Africa
- Authors: Rust, Annegret L
- Date: 2000
- Subjects: Wechsler Adult Intelligence Scale , Intelligence tests -- South Africa , Wechsler Adult Intelligence Scale -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3047 , http://hdl.handle.net/10962/d1002556 , Wechsler Adult Intelligence Scale , Intelligence tests -- South Africa , Wechsler Adult Intelligence Scale -- South Africa
- Description: The Wechsler Adult Intelligence Scale - 3rd Edition (WAIS-III) is the newest of the internationally recognised Wechsler family of intelligence tests. It has been improved in terms of its psychometric properties, neuropsychological assessment abilities and its content. This test is in the process of being standardised by the Human Sciences Research Council (HSRC) in South Africa. As the adapted South African version will be available shortly for use in the multicultural circumstances of South Africa, the application of the various aspects of this test needs to be investigated. This test is very comprehensive and thorough, however its one disadvantage is that it takes on average three hours to administer in its entirety. Thus there is a need to find ways in which to abbreviate the test for particular purposes when time is limited, for example in research, brief clinical assessments or neuropsychological screenings. The concept of abbreviating tests, including the earlier Wechsler intelligence test can be traced back to 1917, when it was asked if all the items on the Binet-Simon scale were required to give an accurate assessment of IQ (Levy, 1968). Since then there have been many short form suggestions made, with many different considerations in mind. These can be divided into two main approaches or methods. Firstly, the number of subtests of the scale can be reduced. Thus with the WAIS-III which consists of 14 subtests in total, an option is to use, for example only four of the subtests to get an estimate of a person's IQ. Secondly, the number of items in each subtest can be reduced. Thus only half the items or even only a third of the items on a subtest can be administered to get an estimate of the persons' performance on each subtest and in this way estimate their overall IQ. Both methods have been used on the WAIS and WAIS-R, although the reduction of the subtests is favoured. Both should now be validated and considered for use with the WATS-III in South Africa. Wechsler tests and their constituent subtests have been found to be differentially effected by race, education, language and socio-economic status (Kaufman, McLean & Reynolds, 1988; Nell 1999). These differences have also been found to impact on the short forms which are suggested, as certain subtests are considered to be more biased towards particular groups than others. Vocabulary and Block Design in particular bias testees who are not as westernised or acculturated towards a largely American and European culture (Kaufman, McLean & Reynolds, 1988). These differences, although often ascribed to race, language or socio-economic status can best be understood more broadly in terms of degree of acculturation (i.e. westernisation) (Shuttleworth-Jordan, 1996) and test-wiseness (Nell, 1999). In South Africa in particular, with its extreme cultural diversity these factors need to be carefully considered when developing short forms. In the present study the development of a short form appropriate to South Africa's diverse cultural circumstances will be approached, through a sample which has been stratified according to gender, first language (English vs. African), quality of schooling received (Private/Model C vs. DET) and level of education achieved (Matric vs. Graduate). Both a subtest reduction method and an item reduction method will be considered to arrive at a short form. The subtest reduction method will be considered further in an attempt to clarify which subtests would be more or less appropriate to include in a short form considering group differences. Finally the thesis will develop suggestions as to which short forms would be best for use in South Africa.
- Full Text:
- Date Issued: 2000
- Authors: Rust, Annegret L
- Date: 2000
- Subjects: Wechsler Adult Intelligence Scale , Intelligence tests -- South Africa , Wechsler Adult Intelligence Scale -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3047 , http://hdl.handle.net/10962/d1002556 , Wechsler Adult Intelligence Scale , Intelligence tests -- South Africa , Wechsler Adult Intelligence Scale -- South Africa
- Description: The Wechsler Adult Intelligence Scale - 3rd Edition (WAIS-III) is the newest of the internationally recognised Wechsler family of intelligence tests. It has been improved in terms of its psychometric properties, neuropsychological assessment abilities and its content. This test is in the process of being standardised by the Human Sciences Research Council (HSRC) in South Africa. As the adapted South African version will be available shortly for use in the multicultural circumstances of South Africa, the application of the various aspects of this test needs to be investigated. This test is very comprehensive and thorough, however its one disadvantage is that it takes on average three hours to administer in its entirety. Thus there is a need to find ways in which to abbreviate the test for particular purposes when time is limited, for example in research, brief clinical assessments or neuropsychological screenings. The concept of abbreviating tests, including the earlier Wechsler intelligence test can be traced back to 1917, when it was asked if all the items on the Binet-Simon scale were required to give an accurate assessment of IQ (Levy, 1968). Since then there have been many short form suggestions made, with many different considerations in mind. These can be divided into two main approaches or methods. Firstly, the number of subtests of the scale can be reduced. Thus with the WAIS-III which consists of 14 subtests in total, an option is to use, for example only four of the subtests to get an estimate of a person's IQ. Secondly, the number of items in each subtest can be reduced. Thus only half the items or even only a third of the items on a subtest can be administered to get an estimate of the persons' performance on each subtest and in this way estimate their overall IQ. Both methods have been used on the WAIS and WAIS-R, although the reduction of the subtests is favoured. Both should now be validated and considered for use with the WATS-III in South Africa. Wechsler tests and their constituent subtests have been found to be differentially effected by race, education, language and socio-economic status (Kaufman, McLean & Reynolds, 1988; Nell 1999). These differences have also been found to impact on the short forms which are suggested, as certain subtests are considered to be more biased towards particular groups than others. Vocabulary and Block Design in particular bias testees who are not as westernised or acculturated towards a largely American and European culture (Kaufman, McLean & Reynolds, 1988). These differences, although often ascribed to race, language or socio-economic status can best be understood more broadly in terms of degree of acculturation (i.e. westernisation) (Shuttleworth-Jordan, 1996) and test-wiseness (Nell, 1999). In South Africa in particular, with its extreme cultural diversity these factors need to be carefully considered when developing short forms. In the present study the development of a short form appropriate to South Africa's diverse cultural circumstances will be approached, through a sample which has been stratified according to gender, first language (English vs. African), quality of schooling received (Private/Model C vs. DET) and level of education achieved (Matric vs. Graduate). Both a subtest reduction method and an item reduction method will be considered to arrive at a short form. The subtest reduction method will be considered further in an attempt to clarify which subtests would be more or less appropriate to include in a short form considering group differences. Finally the thesis will develop suggestions as to which short forms would be best for use in South Africa.
- Full Text:
- Date Issued: 2000
Economic incentives in controlling pollution in the South African leather industry
- Authors: Mowat, Shaun Phillip
- Date: 1996
- Subjects: Leather industry and trade -- South Africa , Tanneries -- Waste disposal -- Economic aspects
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:1010 , http://hdl.handle.net/10962/d1002745 , Leather industry and trade -- South Africa , Tanneries -- Waste disposal -- Economic aspects
- Description: The objective of the research was to ascertain whether, when compared to a system'of standards, the theoretical promise that economic incentives offered as a low cost solution to the abatement problem, would hold in practice. This was done by applying environmental economic theory to the practical problem of controlling the effluent generated by firms in the South African leather industry. It was found that in this instance the theory did indeed hold in practice. Furthermore, it was found that of the incentives discussed by the theory, marketable permits were the most economically efficient. It was however shown that a charge - not discussed in the ., theory - based on a central treatment agency's (CTA) cost of treatment offered the least cost solution to the abatement problem when the CTA could do at least some of the effluent treatment at a lower cost than the firms. - In addition a formula was developed to show the net benefits accruing to an individual firm if it undertook to treat its effluent. It was shown that in order to maximise the total benefits of treatment, a firm should treat until its net benefits of treatment were zero. A number of problem however were found to exist when the theory was applied to a practical situation. The most important was the "stepped" nature of the firms marginal abatement cost curves which meant that the setting of a charge based on a trial and error method would prove to be more difficult than the theory envisaged. Furthermore, it meant that no matter what method of pollution control was used, it would prove i~possible to reduce effluent to an optimal level. It was recommended that greater use be made of economic incentives to control all industrial effluent. It would nonetheless be necessary to do more research in this field as the theory was not tailor made for all practical situations. Further evidence of the viability of economic incentives could however encourage wider use by policy makers.
- Full Text:
- Date Issued: 1996
- Authors: Mowat, Shaun Phillip
- Date: 1996
- Subjects: Leather industry and trade -- South Africa , Tanneries -- Waste disposal -- Economic aspects
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:1010 , http://hdl.handle.net/10962/d1002745 , Leather industry and trade -- South Africa , Tanneries -- Waste disposal -- Economic aspects
- Description: The objective of the research was to ascertain whether, when compared to a system'of standards, the theoretical promise that economic incentives offered as a low cost solution to the abatement problem, would hold in practice. This was done by applying environmental economic theory to the practical problem of controlling the effluent generated by firms in the South African leather industry. It was found that in this instance the theory did indeed hold in practice. Furthermore, it was found that of the incentives discussed by the theory, marketable permits were the most economically efficient. It was however shown that a charge - not discussed in the ., theory - based on a central treatment agency's (CTA) cost of treatment offered the least cost solution to the abatement problem when the CTA could do at least some of the effluent treatment at a lower cost than the firms. - In addition a formula was developed to show the net benefits accruing to an individual firm if it undertook to treat its effluent. It was shown that in order to maximise the total benefits of treatment, a firm should treat until its net benefits of treatment were zero. A number of problem however were found to exist when the theory was applied to a practical situation. The most important was the "stepped" nature of the firms marginal abatement cost curves which meant that the setting of a charge based on a trial and error method would prove to be more difficult than the theory envisaged. Furthermore, it meant that no matter what method of pollution control was used, it would prove i~possible to reduce effluent to an optimal level. It was recommended that greater use be made of economic incentives to control all industrial effluent. It would nonetheless be necessary to do more research in this field as the theory was not tailor made for all practical situations. Further evidence of the viability of economic incentives could however encourage wider use by policy makers.
- Full Text:
- Date Issued: 1996
The geology of the Unki platinum-base metal deposit, Selukwe subchamber, great dyke, Zimbabwe
- Authors: Murahwi, Charley Zvinaiye
- Date: 1996
- Subjects: Platinum ores -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4962 , http://hdl.handle.net/10962/d1005574 , Platinum ores -- Zimbabwe
- Description: This thesis focuses on platinu'm group element (PGE) mineralization in the Unki Section of the Selukwe Subchamber of the Great Dyke (Zimbabwe), and is based on drill hole intersections and underground and surface exposures of the Main Sulphide Zone (MSZ) which hosts significant concentrations of PGE. The petrological and geochemical data presented are part of a broader study currently underway and the present are restricted to the 2m section of the PGE-rich MSZ encountered in drill hole MR126. The PGE-rich MSZ at Unki is unique in having a shear, locally referred to as the Footwall Shear, developed at or close to its base . It is however, similar to the other PGE occurrences on the Great Dyke (MSZ) in having its hanging-wall restricted to within 1m of the websterite/bronzitite contact. Slight axial tilting to t he west is indicated by steeper dips on the eastern flank. The sulphide concentration wit hin the MSZ can be used as a rough guide to the PGE-rich zone, but is not sufficiently precise to be used in stope control. The visual identification of the potentially mineable zone remains a problem that is unlikely to be solved. Based on petrological evidence, the bulk of the sulphides with which the PGE are associated, are cumulus in status. This provides unequivocal evidence for an orthomagmatic origin of the MSZ. The dominant platinum group mineral (PGM) phase is the Arsenide/Sperrylite group which is most commonly found at the contact zones between base metal sulphides (BMS) and gangue. The PGM range up to 90 ~m in length. Geochemical evidence from the analyses of cumulate orthopyroxenes through the 2m PGE-rich MSZ interval at Unki reveals a trend of arked Fe enrichment upwards which corresponds to an enrichment in sulphide. This indicates that precipitation of sulphide was caused by fractionation with lowering of temperature in the magma. The Fe enrichment is followed by a reversal in Mg# of orthopyroxene which corresponds to the decrease in sulphide content, suggest i ng that the termination of the PGE-rich MSZ was due to an increase in temperature associated with an influx of new magma. Coupled with these magmatic events are a complex interplay of chemical and physical processes occurring at a critical stage in the overall fractionation of the Great Dyke magma chamber. The overall persistence and continuity of t he PGE zone as observed in the Unki area is consistent with the inferred orthomagmatic origin of the mineralization
- Full Text:
- Date Issued: 1996
- Authors: Murahwi, Charley Zvinaiye
- Date: 1996
- Subjects: Platinum ores -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4962 , http://hdl.handle.net/10962/d1005574 , Platinum ores -- Zimbabwe
- Description: This thesis focuses on platinu'm group element (PGE) mineralization in the Unki Section of the Selukwe Subchamber of the Great Dyke (Zimbabwe), and is based on drill hole intersections and underground and surface exposures of the Main Sulphide Zone (MSZ) which hosts significant concentrations of PGE. The petrological and geochemical data presented are part of a broader study currently underway and the present are restricted to the 2m section of the PGE-rich MSZ encountered in drill hole MR126. The PGE-rich MSZ at Unki is unique in having a shear, locally referred to as the Footwall Shear, developed at or close to its base . It is however, similar to the other PGE occurrences on the Great Dyke (MSZ) in having its hanging-wall restricted to within 1m of the websterite/bronzitite contact. Slight axial tilting to t he west is indicated by steeper dips on the eastern flank. The sulphide concentration wit hin the MSZ can be used as a rough guide to the PGE-rich zone, but is not sufficiently precise to be used in stope control. The visual identification of the potentially mineable zone remains a problem that is unlikely to be solved. Based on petrological evidence, the bulk of the sulphides with which the PGE are associated, are cumulus in status. This provides unequivocal evidence for an orthomagmatic origin of the MSZ. The dominant platinum group mineral (PGM) phase is the Arsenide/Sperrylite group which is most commonly found at the contact zones between base metal sulphides (BMS) and gangue. The PGM range up to 90 ~m in length. Geochemical evidence from the analyses of cumulate orthopyroxenes through the 2m PGE-rich MSZ interval at Unki reveals a trend of arked Fe enrichment upwards which corresponds to an enrichment in sulphide. This indicates that precipitation of sulphide was caused by fractionation with lowering of temperature in the magma. The Fe enrichment is followed by a reversal in Mg# of orthopyroxene which corresponds to the decrease in sulphide content, suggest i ng that the termination of the PGE-rich MSZ was due to an increase in temperature associated with an influx of new magma. Coupled with these magmatic events are a complex interplay of chemical and physical processes occurring at a critical stage in the overall fractionation of the Great Dyke magma chamber. The overall persistence and continuity of t he PGE zone as observed in the Unki area is consistent with the inferred orthomagmatic origin of the mineralization
- Full Text:
- Date Issued: 1996
An exploratory survey of the needs and adjustment to retirement of persons residing in Port Alfred
- Authors: Stephens, Brent William
- Date: 1995
- Subjects: Retirement, Places of -- South Africa -- Eastern Cape -- Port Alfred , Older people -- South Africa -- Eastern Cape -- Port Alfred -- Social conditions , Older people -- South Africa -- Eastern Cape -- Port Alfred , Older people -- South Africa -- Eastern Cape -- Port Alfred -- Economic conditions , Retirees -- South Africa -- Eastern Cape -- Port Alfred
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3283 , http://hdl.handle.net/10962/d1006514 , Retirement, Places of -- South Africa -- Eastern Cape -- Port Alfred , Older people -- South Africa -- Eastern Cape -- Port Alfred -- Social conditions , Older people -- South Africa -- Eastern Cape -- Port Alfred , Older people -- South Africa -- Eastern Cape -- Port Alfred -- Economic conditions , Retirees -- South Africa -- Eastern Cape -- Port Alfred
- Description: The problem that was chosen to be investigated, was that, within the white middle class South African white-collar worker there appears to be a tendency to live for the "pie in the sky" - which for most seems to be retirement to the idyllic cottage by the sea. Within the South African scenario, there seems to be a definite lack of career planning or at least planning for retirement, other than the financial emphasis. Upon reaching the "ultimate" retirement, retirees take their pension money and move to the coast, expecting pure bliss. The result of their lack of forethought is that they settle in a totally different climate, away from the support of family and friends, possibly finding their income inadequate, with the result that many fall seriously ill, and then discover a lack of geriatric care or a hospital at the time in their lives when they need it the most. The aim of the research was to investigate these issues using a specific location - Port Alfred, researching the fact that Port Alfred continues to be a retirement haven, despite appearing to lack the necessary facilities required by the elderly. The method of the research was to initially administer a pilot questionnaire to a few elderly residents at random, which was then followed up by the formal personally administered questionnaire to a sample. The sample of retired elderly residents in Port Alfred was chosen at random primarily from the various old age homes in Port Alfred. This questionnaire was administered in 1983 but due to financial and personal reasons, the results were not written up. In 1990, the research was continued with a further questionnaire being administered in 1991. The research direction was altered slightly to identify not only what resources were felt to be lacking, but also to identify how well the retired persons of Port Alfred had managed their transition to retirement. The results showed some similarity between the 1983 and the 1991 research. On the surface the retirees appeared well-adjusted and content, but when it was delved deeper, they appeared to have opted out of making any great effort to change their situation, but rather had taken the view that they had earned their rest, would make the best of what they had, and leave it to someone else to champion their cause. This meant that they relied heavily upon those in their community to meet their obvious needs. The promised hospital that they had arduously raised funds for had not materialised, and that seemed to have been the last effort that they had been prepared to make, they were now at rest. The conclusion was that, although the retirees had made the best of their situation, this definitely did not mean that their resources were adequate. Various charities and social services were at work in the community to redress the imbalance, but it was felt that these would in turn benefit by the addition of a social worker. This social worker would coordinate these services and take responsibility for the community at large, particularly addressing the need to unify the services with those to the large non-White community, in the (on-going) development of the New South Africa
- Full Text:
- Date Issued: 1995
- Authors: Stephens, Brent William
- Date: 1995
- Subjects: Retirement, Places of -- South Africa -- Eastern Cape -- Port Alfred , Older people -- South Africa -- Eastern Cape -- Port Alfred -- Social conditions , Older people -- South Africa -- Eastern Cape -- Port Alfred , Older people -- South Africa -- Eastern Cape -- Port Alfred -- Economic conditions , Retirees -- South Africa -- Eastern Cape -- Port Alfred
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3283 , http://hdl.handle.net/10962/d1006514 , Retirement, Places of -- South Africa -- Eastern Cape -- Port Alfred , Older people -- South Africa -- Eastern Cape -- Port Alfred -- Social conditions , Older people -- South Africa -- Eastern Cape -- Port Alfred , Older people -- South Africa -- Eastern Cape -- Port Alfred -- Economic conditions , Retirees -- South Africa -- Eastern Cape -- Port Alfred
- Description: The problem that was chosen to be investigated, was that, within the white middle class South African white-collar worker there appears to be a tendency to live for the "pie in the sky" - which for most seems to be retirement to the idyllic cottage by the sea. Within the South African scenario, there seems to be a definite lack of career planning or at least planning for retirement, other than the financial emphasis. Upon reaching the "ultimate" retirement, retirees take their pension money and move to the coast, expecting pure bliss. The result of their lack of forethought is that they settle in a totally different climate, away from the support of family and friends, possibly finding their income inadequate, with the result that many fall seriously ill, and then discover a lack of geriatric care or a hospital at the time in their lives when they need it the most. The aim of the research was to investigate these issues using a specific location - Port Alfred, researching the fact that Port Alfred continues to be a retirement haven, despite appearing to lack the necessary facilities required by the elderly. The method of the research was to initially administer a pilot questionnaire to a few elderly residents at random, which was then followed up by the formal personally administered questionnaire to a sample. The sample of retired elderly residents in Port Alfred was chosen at random primarily from the various old age homes in Port Alfred. This questionnaire was administered in 1983 but due to financial and personal reasons, the results were not written up. In 1990, the research was continued with a further questionnaire being administered in 1991. The research direction was altered slightly to identify not only what resources were felt to be lacking, but also to identify how well the retired persons of Port Alfred had managed their transition to retirement. The results showed some similarity between the 1983 and the 1991 research. On the surface the retirees appeared well-adjusted and content, but when it was delved deeper, they appeared to have opted out of making any great effort to change their situation, but rather had taken the view that they had earned their rest, would make the best of what they had, and leave it to someone else to champion their cause. This meant that they relied heavily upon those in their community to meet their obvious needs. The promised hospital that they had arduously raised funds for had not materialised, and that seemed to have been the last effort that they had been prepared to make, they were now at rest. The conclusion was that, although the retirees had made the best of their situation, this definitely did not mean that their resources were adequate. Various charities and social services were at work in the community to redress the imbalance, but it was felt that these would in turn benefit by the addition of a social worker. This social worker would coordinate these services and take responsibility for the community at large, particularly addressing the need to unify the services with those to the large non-White community, in the (on-going) development of the New South Africa
- Full Text:
- Date Issued: 1995
Routing MIDI messages in a shared music studio environment
- Authors: Mosala, Thabo Jerry
- Date: 1995
- Subjects: MIDI (Standard) , Computer networks
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4672 , http://hdl.handle.net/10962/d1006695 , MIDI (Standard) , Computer networks
- Description: The Rhodes Computer Music Network (RHOCMN) is a network which allows main studio resources to be shared. RHOCMN is growing into a multi-workstation environment and additional devices are being incorporated into the system. A star configuration is used for transmitting MIDI from a MIDI patch bay to the workstations and MIDI devices. This imposes several disadvantages on the use of the studio, such as wiring problems. In a quest to avoid problems related to MIDI in RHOCMN, the MIDINet system was developed. The idea was to acquire a viable solution to MIDI's main problems which does not involve a redefinition of the MIDI specification.
- Full Text:
- Date Issued: 1995
- Authors: Mosala, Thabo Jerry
- Date: 1995
- Subjects: MIDI (Standard) , Computer networks
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4672 , http://hdl.handle.net/10962/d1006695 , MIDI (Standard) , Computer networks
- Description: The Rhodes Computer Music Network (RHOCMN) is a network which allows main studio resources to be shared. RHOCMN is growing into a multi-workstation environment and additional devices are being incorporated into the system. A star configuration is used for transmitting MIDI from a MIDI patch bay to the workstations and MIDI devices. This imposes several disadvantages on the use of the studio, such as wiring problems. In a quest to avoid problems related to MIDI in RHOCMN, the MIDINet system was developed. The idea was to acquire a viable solution to MIDI's main problems which does not involve a redefinition of the MIDI specification.
- Full Text:
- Date Issued: 1995
The effect of short chain fatty acids on picornavirus replication
- Authors: Ismail-Cassim, Nazeem
- Date: 1993
- Subjects: Viruses -- Reproduction , Picornaviruses , Antiviral agents -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4030 , http://hdl.handle.net/10962/d1004090 , Viruses -- Reproduction , Picornaviruses , Antiviral agents -- Research
- Description: Picornavirus proteins VP1 to VP3 are exposed on the surface of the virus particle whereas VP4 is internal and modified at its amino terminus by the addition of myristic acid (Chow et al., 1987; Paul et al., 1987). Myristic acid occupies a position in the core of mature poliovirus particles; it has been suggested that it may be important for particle integrity or in the localization of the capsid protein precursor on the hydrophobic membranes during virion assembly (Chow et al., 1987). To determine the function of the amino-terminal myristylation of VP4 in picornaviruses, and to establish whether competition for the acylation site is a possible approach to antiviral chemotherapy, the effect of fatty acids on virus replication has been examined. Some fatty acids are able to enter picornavirus-infected cells and compete for the myristylation site on VP4. Unexpectedly, it was found that short chain fatty acids also inhibit an early event in the replication of bovine enterovirus (BEV) at concentrations which have no detectable effect on cellular macromolecular synthesis and cloning. These findings indicate that fatty acids inhibit cell-mediated uncoating. Short chain fatty acids inhibit the replication of bovine enterovirus but are almost ineffective against poliovirus type 1, coxsackievirus B5, encephalomyocarditis virus and human rhinovirus lB. Lauric acid binds to bovine enterovirus, thereby stabilizing the virus particle to heat degradation. Fatty acid-bound virions attach to susceptible cells but fail to undergo cell-mediated uncoating. The inhibitory effect is reversible with chloroform and may result from a hydrophobic interaction between the fatty acid and a specific site on the virus particie.
- Full Text:
- Date Issued: 1993
- Authors: Ismail-Cassim, Nazeem
- Date: 1993
- Subjects: Viruses -- Reproduction , Picornaviruses , Antiviral agents -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4030 , http://hdl.handle.net/10962/d1004090 , Viruses -- Reproduction , Picornaviruses , Antiviral agents -- Research
- Description: Picornavirus proteins VP1 to VP3 are exposed on the surface of the virus particle whereas VP4 is internal and modified at its amino terminus by the addition of myristic acid (Chow et al., 1987; Paul et al., 1987). Myristic acid occupies a position in the core of mature poliovirus particles; it has been suggested that it may be important for particle integrity or in the localization of the capsid protein precursor on the hydrophobic membranes during virion assembly (Chow et al., 1987). To determine the function of the amino-terminal myristylation of VP4 in picornaviruses, and to establish whether competition for the acylation site is a possible approach to antiviral chemotherapy, the effect of fatty acids on virus replication has been examined. Some fatty acids are able to enter picornavirus-infected cells and compete for the myristylation site on VP4. Unexpectedly, it was found that short chain fatty acids also inhibit an early event in the replication of bovine enterovirus (BEV) at concentrations which have no detectable effect on cellular macromolecular synthesis and cloning. These findings indicate that fatty acids inhibit cell-mediated uncoating. Short chain fatty acids inhibit the replication of bovine enterovirus but are almost ineffective against poliovirus type 1, coxsackievirus B5, encephalomyocarditis virus and human rhinovirus lB. Lauric acid binds to bovine enterovirus, thereby stabilizing the virus particle to heat degradation. Fatty acid-bound virions attach to susceptible cells but fail to undergo cell-mediated uncoating. The inhibitory effect is reversible with chloroform and may result from a hydrophobic interaction between the fatty acid and a specific site on the virus particie.
- Full Text:
- Date Issued: 1993
The influence of children on decision-makers in their homes : a case study in environmental education
- Authors: Kruger, Jacqueline
- Date: 1992
- Subjects: Environmental education -- South Africa , Parent and child -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1574 , http://hdl.handle.net/10962/d1003456
- Description: This study explores the possible influence of twenty children on their 'parents', with a view to better understanding the potential 'multiplier effect' of children regarding environmental responsibility. The criteria employed to study the potential influence included certain of the environmental activities learnt by the children during an Environmental Education programme. The programme was undertaken by the researcher with a Std 4 class from Ryneveld Primêreskool in Graaff-Reinet. An action research approach was adopted and results were analysed qualitatively. Due to the short duration and exploratory nature of the project, these results should be viewed as tentative. Proposals are made for increasing the impact of Environmental Education programmes in peri-urban township communities, and recommendations are put forward to help facilitate related studies in the future.
- Full Text:
- Date Issued: 1992
- Authors: Kruger, Jacqueline
- Date: 1992
- Subjects: Environmental education -- South Africa , Parent and child -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1574 , http://hdl.handle.net/10962/d1003456
- Description: This study explores the possible influence of twenty children on their 'parents', with a view to better understanding the potential 'multiplier effect' of children regarding environmental responsibility. The criteria employed to study the potential influence included certain of the environmental activities learnt by the children during an Environmental Education programme. The programme was undertaken by the researcher with a Std 4 class from Ryneveld Primêreskool in Graaff-Reinet. An action research approach was adopted and results were analysed qualitatively. Due to the short duration and exploratory nature of the project, these results should be viewed as tentative. Proposals are made for increasing the impact of Environmental Education programmes in peri-urban township communities, and recommendations are put forward to help facilitate related studies in the future.
- Full Text:
- Date Issued: 1992
An investigation of chlorbutol in ophthalmic and parenteral solutions
- Authors: Summers, Robert Stanley
- Date: 1967
- Subjects: Parenteral solutions , Solutions (Pharmacy) , Ocular pharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3842 , http://hdl.handle.net/10962/d1007694 , Parenteral solutions , Solutions (Pharmacy) , Ocular pharmacology
- Description: From Introduction Chlorbutol , which is tri-chlor-tertiary-butanol, was first prepared by Willgerodt in 1886 (1). The reaction he used for its preparation is still used today, though slightly modified (2)(3)(4), and is suggested by its original name "acetone-chloroform". The substance was prepared by adding solid potassium hydroxide to a cold mixture of acetone and chloroform (5 ). Chlorbutol is a derivative of the trichlorinated derivative of methane, and its formation may best be described by the use of structural formulae.
- Full Text:
- Date Issued: 1967
- Authors: Summers, Robert Stanley
- Date: 1967
- Subjects: Parenteral solutions , Solutions (Pharmacy) , Ocular pharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3842 , http://hdl.handle.net/10962/d1007694 , Parenteral solutions , Solutions (Pharmacy) , Ocular pharmacology
- Description: From Introduction Chlorbutol , which is tri-chlor-tertiary-butanol, was first prepared by Willgerodt in 1886 (1). The reaction he used for its preparation is still used today, though slightly modified (2)(3)(4), and is suggested by its original name "acetone-chloroform". The substance was prepared by adding solid potassium hydroxide to a cold mixture of acetone and chloroform (5 ). Chlorbutol is a derivative of the trichlorinated derivative of methane, and its formation may best be described by the use of structural formulae.
- Full Text:
- Date Issued: 1967
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