The construction of a swept-frequency polarimeter for observing decametric radiation from Jupiter
- Authors: Baker, Dirk E.
- Date: 1970-01
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/447507 , vital:74652
- Description: This thesis describes the design and construction of a swept-frequency polarimeter for observing Jupiter’s decametric radiation in the frequency range from 15 to 45 MHz. The frequency band is tuned in two parts using two receivers for observing the left- and right-circular components of the radiation in the 15 to 26 MHz range and two receivers for observing the circular components in the 30 to 45 MHz range. The receivers are tuned electronically by means of varactor diodes and are of novel design in that they do not have any intermediate-frequency stages. The frequency band can be swept 10 times per second or 100 times per second. The antennas used for the polarimeter are helical beam antennas, two for each of the circular components in the 15 to 26 MHz range and two for the 30 to 45 MHz range. Model studies of the antennas were conducted to establish whether they have suitable characteristics for observing the polarisation of Jupiter’s decametric radiation over a wide frequency range. Many spectral records of Jupiter’s decametric radiation were obtained using a preliminary version of the swept-frequency receiver and a log-periodic dipole antenna. Some of the records are presented and one record which shows an interesting case of Faraday rotation is analysed. , Thesis (MSc) -- Faculty of Science, Physics, 1970
- Full Text:
- Date Issued: 1970-01
- Authors: Baker, Dirk E.
- Date: 1970-01
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/447507 , vital:74652
- Description: This thesis describes the design and construction of a swept-frequency polarimeter for observing Jupiter’s decametric radiation in the frequency range from 15 to 45 MHz. The frequency band is tuned in two parts using two receivers for observing the left- and right-circular components of the radiation in the 15 to 26 MHz range and two receivers for observing the circular components in the 30 to 45 MHz range. The receivers are tuned electronically by means of varactor diodes and are of novel design in that they do not have any intermediate-frequency stages. The frequency band can be swept 10 times per second or 100 times per second. The antennas used for the polarimeter are helical beam antennas, two for each of the circular components in the 15 to 26 MHz range and two for the 30 to 45 MHz range. Model studies of the antennas were conducted to establish whether they have suitable characteristics for observing the polarisation of Jupiter’s decametric radiation over a wide frequency range. Many spectral records of Jupiter’s decametric radiation were obtained using a preliminary version of the swept-frequency receiver and a log-periodic dipole antenna. Some of the records are presented and one record which shows an interesting case of Faraday rotation is analysed. , Thesis (MSc) -- Faculty of Science, Physics, 1970
- Full Text:
- Date Issued: 1970-01
The depositional history and evaluation of two late quaternary, diamondiferous pocket beaches, south-western Namibia
- Authors: Milad, Micael George
- Date: 2004-03
- Subjects: Pocket beach , Geology, Stratigraphic Holocene , Diamond deposits Namibia Sperrgebiet , Prospecting
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/420934 , vital:71795
- Description: The two Late Quaternary, diamondiferous pocket beach deposits studied here are situated along a 10 km stretch of the storm-dominated, Atlantic coastline of the Sperrgebiet, south-western Namibia. The pocket beaches are approximately 130 km north of the Orange River mouth, which is widely accepted as a long-lived point source for diamonds sourced from the interior of southern Africa. A total of fourteen pocket beach deposits were recently evaluated in this area, but only two of these, namely Site 2 (to the south) and Site 3 (to the north), are considered here. The main diamondbearing horizons are beach gravels, which occur within, and form part of, the pocket beach sequences. The beach gravels are mostly blanketed by sand overburden, meaning that exposures available for study were limited, and much reliance was placed on borehole logging and observations of evaluation sample tailings. The main aims are to unravel the depositional history of the pocket beach sequences, identify the controls on diamond mineralisation in the beach gravels, and critically examine two different methods of estimating average diamond size for the deposits. In pursuit of these aims, sedimentological characteristics of the unconsolidated pocket beach deposits were recorded using small diameter drill holes, hydraulic grab bulk samples, trench exposures and surface outcrops. The surface geology, geomorphology and modern wave patterns were mapped using high-resolution, Airborne Laser Survey imagery coupled with extensive field checking. Three-dimensional geological modeling software was used to gain insight into the subsurface morphology of the deposits. Fossil shell samples were used to aid interpretation of ancient depositional environments and to date parts of the pocket beach sequences. Variations in diamond concentration and the size of diamonds were recorded using bulk samples, some of which were taken from a trench, but most of which were excavated using a hydraulic grab tool called the GB50. Finally, by using diamond size data from Site 3, sample data from diamondiferous beach gravels to the south of the study area and sample campaign simulations, two alternative methods of evaluating average diamond size in marine gravel deposits were appraised.The pocket beach sequences occur within north-south trending valleys of a major deflation basin and are separated from one another by rocky headlands. The ridge-and-valley topography of the deflation basin has resulted from differential erosion of Late Proterozoic basement rock units, alternating layers of which differ greatly in their resistance to the long-lived, local denudationalprocesses. On the basis of the stratigraphic information collected from the unconsolidated pocket beach valley fills, interpreted within the context of global, Late Pleistocene sea level records, the following depositional history is deduced : a) Deposition of sheetflood gravels by ephemeral streams, activated during a regressive phase. b) Transgression, culminating in the deposition of a gravel beach, representing a sea level highstand of +4 metres above mean sea level (mamsl) at between 120 000 and 130 000 BP. c)A regressive phase, resulting in deflation of former valley fills to the bedrock valley floor and accompanied by re-activation of ephemeral stream activity to form sheetflood deposits; this represents a protracted period of subaerial exposure of the +4 m gravel beach deposit. d) Deposition of a great volume of sediment in the valleys during the latter stages of the transgression from the Last Glacial Maximum (LGM). The sequence generated during this phase, which started at ca. 9 000 BP, contains : i) pan/coastal sabkha sediments, ii) shallow, sheltered bay sediments, iii) back-barrier lagoonal sediments, iv) a gravel beach deposit representing a sea level stillstand at -5 mamsl, laid down between 7 600 and 5 600 BP, v) another gravel beach deposit representing the well-known Middle Holocene sea level highstand at +2 to +3 mamsl, laid down at ca. 5 000 BP, and which terminated the transgression from the LGM. e) A minor regression to the current sea level, accompanied by progradation of the shoreline to its current position. This progradational marine unit consists almost entirely of sand and grit, reflecting the lack of gravel supply to this part of the coastline in the most recent past. f) Deposition of modern coastal dunes, which cap the pocket beach sequence and are the youngest sediments in the study area. Using trench and hydraulic grab evaluation sample results, in combination with analysis of wave patterns and field observations, the following local controls on the density distribution (ie. concentration) and size distribution of diamonds in the gravel beach deposits (+4, -5 and +2 to +3 mamsl stands) are recognised: a) Gravel beach depositional processes, which are responsible for clast sorting on the beach, have influenced the density and size distribution of diamonds. The infill zone, or beach toe, favours maximum diamond concentration while diamond size decreases from the imbricate zone (intertidal) to the infill zone (subtidal). b) Wave energy is identified as the dominant local control on diamond size distribution, but has also influenced diamond concentration to a limited degree. Larger diamonds are intimately associated with coarser beach gravels, both of which are a reflection of increased wave energy. Higher concentrations of diamonds are sometimes associated with zones of coarser gravel and therefore greater wave energy. c) The time of deposition of the host gravel beach is seen to be the dominant controlling factor with respect to diamond concentration. This is seen as evidence of significant temporal variation in the availability of diamonds in the littoral evironment. A significant reduction (20%) in average diamond size from Site 2 to Site 3, over a distance of only 6 km, is evident. The following were identified as reasons for this reduction in diamond size : a) Longshore sorting processes, of which the long-lived northerly littoral drift is a key part, are known to have played a role in the diminution of diamond size northwards from the Orange River mouth point source. However, it is believed that this can only partly account for the observed 20% reduction in diamond size. b) Input of sediment and smaller diamonds at Site 3, reworked out of an older, Eocene-aged marine succession in the hinterland, is recognised as a possible additional reason for the large reduction in diamond size from Site 2 to Site 3. It is also speculated that the large size of the pocket beach at Site 3, relative to Site 2, may have resulted in lower average wave energy at Site 3, with consequent reduced average diamond size. Diamond size in the beach gravels of Site 3, as well as in beach gravels elsewhere in the Sperrgebiet, is seen to be lognormally-distributed within geologically homogeneous zones. In theory, lognormal mean estimators represent the best method of estimating average diamond size in such cases, whereas the arithmetic mean estimator has the tendency to overestimate when large outlier values occur. Lognormal mean estimators have the added benefit of providing for the calculation of confidence limits, which are becoming increasingly more important as financial lending institutions insist on better quantification of the risk involved in resource estimates. Sample campaign simulations demonstrate, for the kinds of diamond size-frequency distributions typical of beach gravel deposits at Site 3, that there is no significant improvement in the accuracy of average diamond size estimates when lognormal mean estimators are used instead of the arithmetic mean estimator. This is because the variance (a ) of the diamond populations is low, and large outlier values are extremely unlikely to occur. However, simulation of a diamond population with high variance, drawn from a sample of beach gravels near the Orange River mouth, shows that lognormal estimators produce significantly more accurate results when a is large. Since individual diamond weights were not recorded during evaluation sampling of Site 3, numerical solution of lognormal estimators is not possible, and these would need to be solved using a less accurate graphical method. It is therefore recommended that individual diamond weights are recorded in future sampling campaigns, allowing for the use of lognormal mean estimators, and the calculation of confidence limits for average diamond size estimates. , Thesis (MSc) -- Science, Geology, 2004
- Full Text:
- Date Issued: 2004-03
- Authors: Milad, Micael George
- Date: 2004-03
- Subjects: Pocket beach , Geology, Stratigraphic Holocene , Diamond deposits Namibia Sperrgebiet , Prospecting
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/420934 , vital:71795
- Description: The two Late Quaternary, diamondiferous pocket beach deposits studied here are situated along a 10 km stretch of the storm-dominated, Atlantic coastline of the Sperrgebiet, south-western Namibia. The pocket beaches are approximately 130 km north of the Orange River mouth, which is widely accepted as a long-lived point source for diamonds sourced from the interior of southern Africa. A total of fourteen pocket beach deposits were recently evaluated in this area, but only two of these, namely Site 2 (to the south) and Site 3 (to the north), are considered here. The main diamondbearing horizons are beach gravels, which occur within, and form part of, the pocket beach sequences. The beach gravels are mostly blanketed by sand overburden, meaning that exposures available for study were limited, and much reliance was placed on borehole logging and observations of evaluation sample tailings. The main aims are to unravel the depositional history of the pocket beach sequences, identify the controls on diamond mineralisation in the beach gravels, and critically examine two different methods of estimating average diamond size for the deposits. In pursuit of these aims, sedimentological characteristics of the unconsolidated pocket beach deposits were recorded using small diameter drill holes, hydraulic grab bulk samples, trench exposures and surface outcrops. The surface geology, geomorphology and modern wave patterns were mapped using high-resolution, Airborne Laser Survey imagery coupled with extensive field checking. Three-dimensional geological modeling software was used to gain insight into the subsurface morphology of the deposits. Fossil shell samples were used to aid interpretation of ancient depositional environments and to date parts of the pocket beach sequences. Variations in diamond concentration and the size of diamonds were recorded using bulk samples, some of which were taken from a trench, but most of which were excavated using a hydraulic grab tool called the GB50. Finally, by using diamond size data from Site 3, sample data from diamondiferous beach gravels to the south of the study area and sample campaign simulations, two alternative methods of evaluating average diamond size in marine gravel deposits were appraised.The pocket beach sequences occur within north-south trending valleys of a major deflation basin and are separated from one another by rocky headlands. The ridge-and-valley topography of the deflation basin has resulted from differential erosion of Late Proterozoic basement rock units, alternating layers of which differ greatly in their resistance to the long-lived, local denudationalprocesses. On the basis of the stratigraphic information collected from the unconsolidated pocket beach valley fills, interpreted within the context of global, Late Pleistocene sea level records, the following depositional history is deduced : a) Deposition of sheetflood gravels by ephemeral streams, activated during a regressive phase. b) Transgression, culminating in the deposition of a gravel beach, representing a sea level highstand of +4 metres above mean sea level (mamsl) at between 120 000 and 130 000 BP. c)A regressive phase, resulting in deflation of former valley fills to the bedrock valley floor and accompanied by re-activation of ephemeral stream activity to form sheetflood deposits; this represents a protracted period of subaerial exposure of the +4 m gravel beach deposit. d) Deposition of a great volume of sediment in the valleys during the latter stages of the transgression from the Last Glacial Maximum (LGM). The sequence generated during this phase, which started at ca. 9 000 BP, contains : i) pan/coastal sabkha sediments, ii) shallow, sheltered bay sediments, iii) back-barrier lagoonal sediments, iv) a gravel beach deposit representing a sea level stillstand at -5 mamsl, laid down between 7 600 and 5 600 BP, v) another gravel beach deposit representing the well-known Middle Holocene sea level highstand at +2 to +3 mamsl, laid down at ca. 5 000 BP, and which terminated the transgression from the LGM. e) A minor regression to the current sea level, accompanied by progradation of the shoreline to its current position. This progradational marine unit consists almost entirely of sand and grit, reflecting the lack of gravel supply to this part of the coastline in the most recent past. f) Deposition of modern coastal dunes, which cap the pocket beach sequence and are the youngest sediments in the study area. Using trench and hydraulic grab evaluation sample results, in combination with analysis of wave patterns and field observations, the following local controls on the density distribution (ie. concentration) and size distribution of diamonds in the gravel beach deposits (+4, -5 and +2 to +3 mamsl stands) are recognised: a) Gravel beach depositional processes, which are responsible for clast sorting on the beach, have influenced the density and size distribution of diamonds. The infill zone, or beach toe, favours maximum diamond concentration while diamond size decreases from the imbricate zone (intertidal) to the infill zone (subtidal). b) Wave energy is identified as the dominant local control on diamond size distribution, but has also influenced diamond concentration to a limited degree. Larger diamonds are intimately associated with coarser beach gravels, both of which are a reflection of increased wave energy. Higher concentrations of diamonds are sometimes associated with zones of coarser gravel and therefore greater wave energy. c) The time of deposition of the host gravel beach is seen to be the dominant controlling factor with respect to diamond concentration. This is seen as evidence of significant temporal variation in the availability of diamonds in the littoral evironment. A significant reduction (20%) in average diamond size from Site 2 to Site 3, over a distance of only 6 km, is evident. The following were identified as reasons for this reduction in diamond size : a) Longshore sorting processes, of which the long-lived northerly littoral drift is a key part, are known to have played a role in the diminution of diamond size northwards from the Orange River mouth point source. However, it is believed that this can only partly account for the observed 20% reduction in diamond size. b) Input of sediment and smaller diamonds at Site 3, reworked out of an older, Eocene-aged marine succession in the hinterland, is recognised as a possible additional reason for the large reduction in diamond size from Site 2 to Site 3. It is also speculated that the large size of the pocket beach at Site 3, relative to Site 2, may have resulted in lower average wave energy at Site 3, with consequent reduced average diamond size. Diamond size in the beach gravels of Site 3, as well as in beach gravels elsewhere in the Sperrgebiet, is seen to be lognormally-distributed within geologically homogeneous zones. In theory, lognormal mean estimators represent the best method of estimating average diamond size in such cases, whereas the arithmetic mean estimator has the tendency to overestimate when large outlier values occur. Lognormal mean estimators have the added benefit of providing for the calculation of confidence limits, which are becoming increasingly more important as financial lending institutions insist on better quantification of the risk involved in resource estimates. Sample campaign simulations demonstrate, for the kinds of diamond size-frequency distributions typical of beach gravel deposits at Site 3, that there is no significant improvement in the accuracy of average diamond size estimates when lognormal mean estimators are used instead of the arithmetic mean estimator. This is because the variance (a ) of the diamond populations is low, and large outlier values are extremely unlikely to occur. However, simulation of a diamond population with high variance, drawn from a sample of beach gravels near the Orange River mouth, shows that lognormal estimators produce significantly more accurate results when a is large. Since individual diamond weights were not recorded during evaluation sampling of Site 3, numerical solution of lognormal estimators is not possible, and these would need to be solved using a less accurate graphical method. It is therefore recommended that individual diamond weights are recorded in future sampling campaigns, allowing for the use of lognormal mean estimators, and the calculation of confidence limits for average diamond size estimates. , Thesis (MSc) -- Science, Geology, 2004
- Full Text:
- Date Issued: 2004-03
The economic contribution of the tourism accommodation sector in the Karoo
- Authors: Chandler, Biddy Lee
- Date: 2013-04-06
- Subjects: Hospitality industry South Africa Karoo , Karoo (South Africa) Economic conditions , Small cities South Africa Karoo , Tourism South Africa Karoo
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/366169 , vital:65838
- Description: Tourism is not only the world’s largest traded commodity in which many countries have gained economic advantage and stability, it is also a phenomenon of great economic and social significance. Tourism’s contribution, especially within developing countries and within emerging markets like South Africa, has become increasingly significant as it has created major economic growth and has highlighted areas of potential new sustainable development. The ultimate goal of achieving an increase in GDP and the creation of new employment opportunities is enhanced through the development of tourism. Considering the importance of the above and because the impact of tourism development in small towns is of significant economic benefit, research into this field is of value. This is the core of this study. As a result of tourism demand continually changing in small towns, mostly due to globalisation, demographic changes and agricultural changes, the need to continually update tourism data to ensure that tourism products remain highly rated is vital. This requires identifying tourists’ needs and supplying exactly what tourists demand. More specifically, evaluating tourist satisfaction and dissatisfaction will give accurate indications of a destination’s ability to satisfy its tourists, which is what will encourage repeat visits. The first objective of this dissertation was to qualitatively evaluate, through determining 27 product owners’ and 206 tourists’, opinions/perceptions of the tourism product offering in the Karoo. This study examined the accommodation sector of the tourism industry within 13 small towns in the Karoo. This is a fast growing and maturing industry. The study revealed that product owners and tourists expressed a positive attitude towards the growth of tourism in the Karoo, which they said was due to its heritage and authenticity, climate, desert tourism, natural beauty, ecotourism, remoteness, peace and quiet and acting as a refuge in an unspoilt natural environment. Amongst other recommendations, this result highlighted the importance of keeping closed the ‘gap’ between the expected product/level of service and the customer’s perception of the actual product/service received, by paying special attention to each of the identified tourist benefits. Most importantly, product owners, local tourism organisations (LTOs), municipalities, the government and all tourism stakeholders need to ensure that they work efficiently and effectively through transparent and collaborative relationships to ensure that they generate the highest possible returns from tourism investment through strategies that take cognizance of the above. The second objective of this dissertation was to quantitatively evaluate the economic impact of tourism through gathering and calculating 107 tourists’ spending data and 15 product owners’ expenditure data over a six month period between December 2010 and May 2011 in Graaff-Reinet. It was found that there was an increase over time in tourist spending, which led to an increase in direct income (net injection of visitor spending) and thus there was an increase in indirect income(affecting the level of product owners’ income)in the Graaff-Reinet economy. The key calculations in this study reflected a high multiplier of 1.2and a small amount of leakage (21%);and the final tourism economic impact of the accommodation sector in Graaff-Reinet wasR8940 982.00. This implies a positive economic contribution to this town. A focus on growing the tourist market is therefore a goal worth pursuing. This study provides up-to-date, statistically valid numerical/quantitative data as well as current qualitative data. However, gathering data for a longitudinal study would be highly beneficial to determine trends of how the tourism market in small towns is developing. This field has been given minimal attention, specifically within small towns. This dissertation was thus an attempt to initiate and motivate further ongoing efforts with regards to gathering, specifically economic, tourism data. Showing the positive economic contribution, and the multiple ripple effects that attracting tourists to an area can have, and the ultimate measurable economic benefit created through having a strong multiplier effect, will hopefully encourage all stakeholders to be confident and take the tourism industry more seriously. This highlights the need to recognise the economic impact potential of the tourism sector and to use the positive results identified in this study as a tool to lobby for tourism investment, which is unfortunately not reflected currently in many governmental programmes. Developing greater co-operation and co-ordination between the private and public sectors is needed: the most appropriate development model for the tourism industry being government led, private sector driven, community based and labour conscious in order for it to reap the benefits reflected in this tourism study. , Thesis (MEcon) -- Faculty of Commerce, Economics and Economic History, 2013
- Full Text:
- Date Issued: 2013-04-06
- Authors: Chandler, Biddy Lee
- Date: 2013-04-06
- Subjects: Hospitality industry South Africa Karoo , Karoo (South Africa) Economic conditions , Small cities South Africa Karoo , Tourism South Africa Karoo
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/366169 , vital:65838
- Description: Tourism is not only the world’s largest traded commodity in which many countries have gained economic advantage and stability, it is also a phenomenon of great economic and social significance. Tourism’s contribution, especially within developing countries and within emerging markets like South Africa, has become increasingly significant as it has created major economic growth and has highlighted areas of potential new sustainable development. The ultimate goal of achieving an increase in GDP and the creation of new employment opportunities is enhanced through the development of tourism. Considering the importance of the above and because the impact of tourism development in small towns is of significant economic benefit, research into this field is of value. This is the core of this study. As a result of tourism demand continually changing in small towns, mostly due to globalisation, demographic changes and agricultural changes, the need to continually update tourism data to ensure that tourism products remain highly rated is vital. This requires identifying tourists’ needs and supplying exactly what tourists demand. More specifically, evaluating tourist satisfaction and dissatisfaction will give accurate indications of a destination’s ability to satisfy its tourists, which is what will encourage repeat visits. The first objective of this dissertation was to qualitatively evaluate, through determining 27 product owners’ and 206 tourists’, opinions/perceptions of the tourism product offering in the Karoo. This study examined the accommodation sector of the tourism industry within 13 small towns in the Karoo. This is a fast growing and maturing industry. The study revealed that product owners and tourists expressed a positive attitude towards the growth of tourism in the Karoo, which they said was due to its heritage and authenticity, climate, desert tourism, natural beauty, ecotourism, remoteness, peace and quiet and acting as a refuge in an unspoilt natural environment. Amongst other recommendations, this result highlighted the importance of keeping closed the ‘gap’ between the expected product/level of service and the customer’s perception of the actual product/service received, by paying special attention to each of the identified tourist benefits. Most importantly, product owners, local tourism organisations (LTOs), municipalities, the government and all tourism stakeholders need to ensure that they work efficiently and effectively through transparent and collaborative relationships to ensure that they generate the highest possible returns from tourism investment through strategies that take cognizance of the above. The second objective of this dissertation was to quantitatively evaluate the economic impact of tourism through gathering and calculating 107 tourists’ spending data and 15 product owners’ expenditure data over a six month period between December 2010 and May 2011 in Graaff-Reinet. It was found that there was an increase over time in tourist spending, which led to an increase in direct income (net injection of visitor spending) and thus there was an increase in indirect income(affecting the level of product owners’ income)in the Graaff-Reinet economy. The key calculations in this study reflected a high multiplier of 1.2and a small amount of leakage (21%);and the final tourism economic impact of the accommodation sector in Graaff-Reinet wasR8940 982.00. This implies a positive economic contribution to this town. A focus on growing the tourist market is therefore a goal worth pursuing. This study provides up-to-date, statistically valid numerical/quantitative data as well as current qualitative data. However, gathering data for a longitudinal study would be highly beneficial to determine trends of how the tourism market in small towns is developing. This field has been given minimal attention, specifically within small towns. This dissertation was thus an attempt to initiate and motivate further ongoing efforts with regards to gathering, specifically economic, tourism data. Showing the positive economic contribution, and the multiple ripple effects that attracting tourists to an area can have, and the ultimate measurable economic benefit created through having a strong multiplier effect, will hopefully encourage all stakeholders to be confident and take the tourism industry more seriously. This highlights the need to recognise the economic impact potential of the tourism sector and to use the positive results identified in this study as a tool to lobby for tourism investment, which is unfortunately not reflected currently in many governmental programmes. Developing greater co-operation and co-ordination between the private and public sectors is needed: the most appropriate development model for the tourism industry being government led, private sector driven, community based and labour conscious in order for it to reap the benefits reflected in this tourism study. , Thesis (MEcon) -- Faculty of Commerce, Economics and Economic History, 2013
- Full Text:
- Date Issued: 2013-04-06
Development and assessment of gastroretentive sustained release captopril tablets
- Authors: Mukozhiwa, Samantha Yolanda
- Date: 2014-04-11
- Subjects: Captopril , Drug delivery systems , Drugs Controlled release , Cardiovascular system Diseases , Cardiovascular agents , Angiotensin converting enzyme Inhibitors
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/480301 , vital:78427
- Description: Cardiovascular diseases (CVD) are the leading cause of death worldwide and global projections predict that the number of deaths due to CVD will continue to increase over the next 17 years [1]. With the growing burden of CVD the design and development of formulations that optimise the delivery of existing therapeutic molecules may be an approach to improving the management of patients with CVD. Captopril (CPT) is an angiotensin converting enzyme (ACE) inhibitor used for the routine management of hypertension, cardiac failure and diabetic nephropathy [2-4]. However it has a relatively short half-life and typical therapeutic dosing regimens require multiple dosing [2]. CPT is a potential candidate for sustained oral drug delivery, however its poor stability profile and high water solubility present significant formulation challenges. CPT exhibits optimal stability at pH < 4 and is unstable in the alkaline environment of intestinal fluids [5]. A sustained release gastroretentive formulation is therefore proposed as an approach that may improve the in vivo stability of CPT in addition to slowly releasing the molecule at a desired rate that may also minimize the occurrence of drug-related adverse effects. A Capillary Zone Electrophoresis (CZE) method for the quantitation of CPT in pharmaceutical dosage forms was developed and optimised using a Central Composite Design (CCD) approach. The CZE method was found to have the necessary linearity, accuracy, precision, sensitivity and specificity for the analysis of CPT in pharmaceutical formulations. Preformulation studies were conducted as part of the preparative work required to manufacture high quality, stable gastroretentive sustained release CPT tablets. The experiments conducted were tailored for the development of CPT sustained release tablets using direct compression manufacture and included an analysis of particle size and shape, powder flow properties and CPT-excipient compatibility studies. The results revealed that there was no definite evidence of interactions between CPT and the excipients to be used to manufacture CPT tablets, and CPT formulations were developed using these excipients. A direct compression procedure was selected for tablet manufacture due to apparent simplicity and to avoid unnecessary exposure of CPT to the heat and moisture that would be encountered if a wet granulation manufacturing process was used. A numerical optimisation approach was used to predict a formulation composition that would produce minimal CPT release initially, a short floating lag time (FLT) and maximum CPT release after 12 hours of dissolution testing. The effect of increasing the agitation speed of USP Apparatus 2 on the release of CPT from the optimised formulation was also investigated. The results revealed that changing the speed of the paddle had only a relatively small impact on the in vitro release behaviour of CPT from the tablets. The optimised formulation was subjected to additional testing in an attempt to investigate the effects of pH and osmolarity on the swelling and erosion characteristics of the dosage form. It was important to evaluate the effects of pH and osmolarity from the perspective of the solubility and stability of CPT. The results generated from swelling studies revealed that the swelling characteristics of the proposed formulation were not significantly altered by a change in pH and osmolarity of the test medium and this is probably due to the non-ionic nature of HPMC. In addition, the results revealed that the solubility and/or stability of CPT in different dissolution media did not affect the water uptake and swelling of the tablet matrices. The results revealed the erosion rate constants were low and suggest that although polymer erosion does occur, the role of this phenomenon in the release of CPT may not be as significant as that of diffusion. The release kinetics of CPT from the tablets was established by fitting in vitro release data to several mathematical models. The in vitro release data were best described using the Korsmeyer-Peppas model and values of release exponent (n) suggest that the majority of the tablets exhibited an anomalous CPT transport mechanism. The short-term stability of the optimised formulation was established by undertaking stability studies at 25°/60% RH and 40°/75% RH. The results revealed that there was no significant change in appearance and physicochemical properties of the tablets over 60 days. In conclusion, gastroretentive sustained release CPT tablets with the potential for further development and optimisation have been successfully developed and assessed in these studies. A basis is thus provided for further development of this technology. , Thesis (MSc (Pharm)) -- Faculty of Pharmacy, 2014
- Full Text:
- Date Issued: 2014-04-11
- Authors: Mukozhiwa, Samantha Yolanda
- Date: 2014-04-11
- Subjects: Captopril , Drug delivery systems , Drugs Controlled release , Cardiovascular system Diseases , Cardiovascular agents , Angiotensin converting enzyme Inhibitors
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/480301 , vital:78427
- Description: Cardiovascular diseases (CVD) are the leading cause of death worldwide and global projections predict that the number of deaths due to CVD will continue to increase over the next 17 years [1]. With the growing burden of CVD the design and development of formulations that optimise the delivery of existing therapeutic molecules may be an approach to improving the management of patients with CVD. Captopril (CPT) is an angiotensin converting enzyme (ACE) inhibitor used for the routine management of hypertension, cardiac failure and diabetic nephropathy [2-4]. However it has a relatively short half-life and typical therapeutic dosing regimens require multiple dosing [2]. CPT is a potential candidate for sustained oral drug delivery, however its poor stability profile and high water solubility present significant formulation challenges. CPT exhibits optimal stability at pH < 4 and is unstable in the alkaline environment of intestinal fluids [5]. A sustained release gastroretentive formulation is therefore proposed as an approach that may improve the in vivo stability of CPT in addition to slowly releasing the molecule at a desired rate that may also minimize the occurrence of drug-related adverse effects. A Capillary Zone Electrophoresis (CZE) method for the quantitation of CPT in pharmaceutical dosage forms was developed and optimised using a Central Composite Design (CCD) approach. The CZE method was found to have the necessary linearity, accuracy, precision, sensitivity and specificity for the analysis of CPT in pharmaceutical formulations. Preformulation studies were conducted as part of the preparative work required to manufacture high quality, stable gastroretentive sustained release CPT tablets. The experiments conducted were tailored for the development of CPT sustained release tablets using direct compression manufacture and included an analysis of particle size and shape, powder flow properties and CPT-excipient compatibility studies. The results revealed that there was no definite evidence of interactions between CPT and the excipients to be used to manufacture CPT tablets, and CPT formulations were developed using these excipients. A direct compression procedure was selected for tablet manufacture due to apparent simplicity and to avoid unnecessary exposure of CPT to the heat and moisture that would be encountered if a wet granulation manufacturing process was used. A numerical optimisation approach was used to predict a formulation composition that would produce minimal CPT release initially, a short floating lag time (FLT) and maximum CPT release after 12 hours of dissolution testing. The effect of increasing the agitation speed of USP Apparatus 2 on the release of CPT from the optimised formulation was also investigated. The results revealed that changing the speed of the paddle had only a relatively small impact on the in vitro release behaviour of CPT from the tablets. The optimised formulation was subjected to additional testing in an attempt to investigate the effects of pH and osmolarity on the swelling and erosion characteristics of the dosage form. It was important to evaluate the effects of pH and osmolarity from the perspective of the solubility and stability of CPT. The results generated from swelling studies revealed that the swelling characteristics of the proposed formulation were not significantly altered by a change in pH and osmolarity of the test medium and this is probably due to the non-ionic nature of HPMC. In addition, the results revealed that the solubility and/or stability of CPT in different dissolution media did not affect the water uptake and swelling of the tablet matrices. The results revealed the erosion rate constants were low and suggest that although polymer erosion does occur, the role of this phenomenon in the release of CPT may not be as significant as that of diffusion. The release kinetics of CPT from the tablets was established by fitting in vitro release data to several mathematical models. The in vitro release data were best described using the Korsmeyer-Peppas model and values of release exponent (n) suggest that the majority of the tablets exhibited an anomalous CPT transport mechanism. The short-term stability of the optimised formulation was established by undertaking stability studies at 25°/60% RH and 40°/75% RH. The results revealed that there was no significant change in appearance and physicochemical properties of the tablets over 60 days. In conclusion, gastroretentive sustained release CPT tablets with the potential for further development and optimisation have been successfully developed and assessed in these studies. A basis is thus provided for further development of this technology. , Thesis (MSc (Pharm)) -- Faculty of Pharmacy, 2014
- Full Text:
- Date Issued: 2014-04-11
Sorption and emulsion liquid membranes in the remediation of metal processing waste water effluents using rhodium, trioctylamine and trihexylamine as a model
- Authors: Moyo, Francis
- Date: 2014-04-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/480289 , vital:78426
- Description: Two optimised ELMs were prepared with the diluent always being 30 % solution of toluene in kerosene. The first ELM contained 30.000 g/L (w/v) polyisobutylene, 10.870 g/L (m/v) of trioctyl amine and 51.001 g/L (m/v) of SPAN 80. The other optimised ELM was composed of 20.000 g/l of polyisobutylene, 10.268 g/l trioctyl amine and 50.024 g/l of SPAN 80. The stripping phase was always 2 M HNO3 and the mixing ratios of organic phase to stripping phase were 1:1 and 2:1. The t-test was used to test for the difference between the mean micro-droplet sizes had a p-value of 0.3018 at 5 % level of significance, i.e. there was no statistically the mean micro-droplet size of the optimised ELMs. Demulsification was performed with polyethylene glycol with molecular weight of 400 g/mol at 50 ± 1 °C for 24 hours. The volumetric ratio of treated side-stream and the ELM was 5:1 and 98.7 to 108 % of the initial Rh amount was recovered in the stripping phase after chemical demulsification. Major carryover of the diluent components into the stripping phase observed was from trioctyl amine, toluene and polyethylene glycol was observed. The final spent side-stream should not be discharged into the environment based on the acute Daphnia pulex toxicity test. For sorption studies, the specific surface area of kaolin was 18.21 0.8 m2 g-1 and loss on ignition was 0.0086 0.004 %. Removal efficiencies of trioctyl amine for 10 g of kaolin and particle size 65-100 μm and 101-400 μm were 18.1 % and 17.5 % respectively while sorption capacities were 0.92 g/g and 0.88 g/g respectively. The removal efficiency of 20 g of kaolin was 35.8 % and 33.3 % and sorption capacities were 0.93 g/g and 0.87 g/g respectively. For particle sizes 101-400 μm, the R2 values obtained for Freundlich and Langmuir were 0.9757 and 0.9819 respectively. The n and Kf for Freundlich isotherm were 1.086 and 2.622. Removal efficiency for trihexyl amine for particle size 101-400 μm and 65-100 μm was 28.5 % and 29.3 % respectively while sorption capacities were 0.73 g/g and 0.75 g/g respectively. The R2 values obtained for Freundlich and Langmuir for particle sizes 101-400 μm were 0.957 and 0.989 respectively. The n and Kf for Freundlich isotherm were 1.307 and 2.151 respectively. These results suggest that kaolinite could potentially be used in remediation of metal wastewaters containing hydrophobic extractants. , Thesis (MSc (Pharm)) -- Faculty of Pharmacy, 2014
- Full Text:
- Date Issued: 2014-04-11
- Authors: Moyo, Francis
- Date: 2014-04-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/480289 , vital:78426
- Description: Two optimised ELMs were prepared with the diluent always being 30 % solution of toluene in kerosene. The first ELM contained 30.000 g/L (w/v) polyisobutylene, 10.870 g/L (m/v) of trioctyl amine and 51.001 g/L (m/v) of SPAN 80. The other optimised ELM was composed of 20.000 g/l of polyisobutylene, 10.268 g/l trioctyl amine and 50.024 g/l of SPAN 80. The stripping phase was always 2 M HNO3 and the mixing ratios of organic phase to stripping phase were 1:1 and 2:1. The t-test was used to test for the difference between the mean micro-droplet sizes had a p-value of 0.3018 at 5 % level of significance, i.e. there was no statistically the mean micro-droplet size of the optimised ELMs. Demulsification was performed with polyethylene glycol with molecular weight of 400 g/mol at 50 ± 1 °C for 24 hours. The volumetric ratio of treated side-stream and the ELM was 5:1 and 98.7 to 108 % of the initial Rh amount was recovered in the stripping phase after chemical demulsification. Major carryover of the diluent components into the stripping phase observed was from trioctyl amine, toluene and polyethylene glycol was observed. The final spent side-stream should not be discharged into the environment based on the acute Daphnia pulex toxicity test. For sorption studies, the specific surface area of kaolin was 18.21 0.8 m2 g-1 and loss on ignition was 0.0086 0.004 %. Removal efficiencies of trioctyl amine for 10 g of kaolin and particle size 65-100 μm and 101-400 μm were 18.1 % and 17.5 % respectively while sorption capacities were 0.92 g/g and 0.88 g/g respectively. The removal efficiency of 20 g of kaolin was 35.8 % and 33.3 % and sorption capacities were 0.93 g/g and 0.87 g/g respectively. For particle sizes 101-400 μm, the R2 values obtained for Freundlich and Langmuir were 0.9757 and 0.9819 respectively. The n and Kf for Freundlich isotherm were 1.086 and 2.622. Removal efficiency for trihexyl amine for particle size 101-400 μm and 65-100 μm was 28.5 % and 29.3 % respectively while sorption capacities were 0.73 g/g and 0.75 g/g respectively. The R2 values obtained for Freundlich and Langmuir for particle sizes 101-400 μm were 0.957 and 0.989 respectively. The n and Kf for Freundlich isotherm were 1.307 and 2.151 respectively. These results suggest that kaolinite could potentially be used in remediation of metal wastewaters containing hydrophobic extractants. , Thesis (MSc (Pharm)) -- Faculty of Pharmacy, 2014
- Full Text:
- Date Issued: 2014-04-11
“Pragmatic yet principled”: an assessment of Botswana’s foreign policy record as a small state
- Authors: Mahupela, Kabelo Moganegi
- Date: 2014-04-11
- Subjects: Constructivism (Philosophy) , Botswana Foreign relations , States, Small Economic conditions , States, Small Politics and government , Africa Politics and government , Africa Foreign relations
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/480278 , vital:78425
- Description: International Relations (IR) theory has traditionally downplayed the capabilities of small states, focusing rather on how the behaviour of large powers dictates interactions of actors within an anarchic arena. This has been very much the case for the realist/neorealist and to a very large extent neoliberal canons of IR, which privilege the structure of the international environment ahead of the agency of actors. As such, the foreign policy analysis of smaller powers in IR – and especially that of African countries – has been marginalised to the periphery. In response to these oversights, constructivism has posited a set of theories in which state identities and interests are determined by an inter-subjective interactive process that gives meaning to the material world. These set of theories also point out that norms can constrain and indeed energise state behaviour in a socially constructed world. This has thus opened up a space within which small state foreign policy behaviour can be analysed – whether it is through conference diplomacy, negotiation skills or idiosyncratic behaviour predicated upon elite ideas and identities. This thesis draws upon the above framework to assess a number of foreign policy choices embarked upon by Botswana in which she has leveraged herself vis-à-vis more powerful actors. The study looks at how Botswana managed to break out of its hostage station within Southern Africa during apartheid, at a time when Gaborone was surrounded by unfavourable white minority rule (in South Africa, Rhodesia, Angola and Mozambique). The study also evaluates Botswana‟s leveraging of her favourable image perception amongst powerful actors, as well as her negotiation proficiency in managing to punch above her weight and obtain favourable outcomes – thereby mitigating the desperate economic conditions she had inherited from colonialism. In a time where much of Southern Africa (and indeed the continent as a whole) disregard and actively disrupt normative imperatives related to democracy, human rights and the rule of law, the thesis also assesses Botswana‟s principled foreign policy posture. Through these chapters, it will be demonstrated that Botswana is an example of a state that has managed to use a careful combination of pragmatism and principle to show that African small states can indeed exercise agency. , Thesis (MA) -- Faculty of Humanities, Political and International Studies, 2014
- Full Text:
- Date Issued: 2014-04-11
- Authors: Mahupela, Kabelo Moganegi
- Date: 2014-04-11
- Subjects: Constructivism (Philosophy) , Botswana Foreign relations , States, Small Economic conditions , States, Small Politics and government , Africa Politics and government , Africa Foreign relations
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/480278 , vital:78425
- Description: International Relations (IR) theory has traditionally downplayed the capabilities of small states, focusing rather on how the behaviour of large powers dictates interactions of actors within an anarchic arena. This has been very much the case for the realist/neorealist and to a very large extent neoliberal canons of IR, which privilege the structure of the international environment ahead of the agency of actors. As such, the foreign policy analysis of smaller powers in IR – and especially that of African countries – has been marginalised to the periphery. In response to these oversights, constructivism has posited a set of theories in which state identities and interests are determined by an inter-subjective interactive process that gives meaning to the material world. These set of theories also point out that norms can constrain and indeed energise state behaviour in a socially constructed world. This has thus opened up a space within which small state foreign policy behaviour can be analysed – whether it is through conference diplomacy, negotiation skills or idiosyncratic behaviour predicated upon elite ideas and identities. This thesis draws upon the above framework to assess a number of foreign policy choices embarked upon by Botswana in which she has leveraged herself vis-à-vis more powerful actors. The study looks at how Botswana managed to break out of its hostage station within Southern Africa during apartheid, at a time when Gaborone was surrounded by unfavourable white minority rule (in South Africa, Rhodesia, Angola and Mozambique). The study also evaluates Botswana‟s leveraging of her favourable image perception amongst powerful actors, as well as her negotiation proficiency in managing to punch above her weight and obtain favourable outcomes – thereby mitigating the desperate economic conditions she had inherited from colonialism. In a time where much of Southern Africa (and indeed the continent as a whole) disregard and actively disrupt normative imperatives related to democracy, human rights and the rule of law, the thesis also assesses Botswana‟s principled foreign policy posture. Through these chapters, it will be demonstrated that Botswana is an example of a state that has managed to use a careful combination of pragmatism and principle to show that African small states can indeed exercise agency. , Thesis (MA) -- Faculty of Humanities, Political and International Studies, 2014
- Full Text:
- Date Issued: 2014-04-11
Analysis of the role of Hsp90 in colon cancer and cancer stem-like cell biology in vitro using a genetically paired cell line model
- Authors: Slater, Cindy
- Date: 2015-04-09
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/480345 , vital:78433
- Description: Colon cancers are commonly associated with mutations or changes in signaling in the Wnt/β-catenin pathway. Cancer treatments, such as chemotherapy and radiation, are challenged by the limited methods of disease detection and the insufficient elimination of contributing factors, such as cancer stem-like cells (CSC), to metastatic disease. CSC are characterised by their ability to survive anchorage-independently and attribute to therapeutic resistance. To examine the biological changes associated with the progression of human colon cancers and the role of Hsp90 in cancer and CSC biology, SW480 and SW620 genetically paired (isogenic) colon cancer cell lines from the same patient were characterised for populations of putative CSC, tumoursphere (TS) forming ability, cell growth, behaviour and response to anti-cancer therapeutics. The SW480 cell line was established from a primary colon adenocarcinoma and the SW620 was established from a lymph node metastasis of the primary cancer one year later. To address the role of Hsp90 in colon cancer, the sensitivity of cells and TS were analysed in response to geldanamycin and novobiocin, and an isoform-specific approach to the targeting of Hsp90α was developed. Flow cytometric analysis of putative CSC by phenotype revealed variable proportions of cells bearing the CD44+/CD133+ surface protein marker, widely used in the identification of colon CSC, in SW480 and SW620 cells. The paired cell lines maintained similar proportions of putative CSC, identified by the expression of the ABCG2 protein (side population; 1 %) and through high aldehyde dehydrogenase activity (ALDEFLUOR; 6 %). SW480 cells demonstrated greater TS forming efficiency than SW620 cells (49.9 and 35.5 %, respectively) and observations of wound-healing showed SW480 cells to be more migratory than SW620 cells. No difference in response to Hsp90 inhibition was observed between paired cell lines, however SW480 TS resisted treatment with geldanamycin. This the first study to report a dose-dependent increase in TS growth in response to novobiocin inhibition of Hsp90, and to demonstrate that that the sensitivity of SW480 and SW620 TS to oxaliplatin, a common drug for the treatment of metastatic colon cancers, was enhanced by novobiocin, providing promise for the elimination of CSC with combined chemotherapeutics. We analysed the Wnt/β-catenin pathway in response to expression of short hairpin RNA (shRNA) against Hsp90α or a control non-targeting shRNA, under the control of a tetracycline-responsive promoter. Hsp90α knockdown contributed to a deregulated stress response, presenting with reduced Hsp27 and β-catenin protein, but corresponded to an increase in the association between Hsp90, β-catenin and Hsp27 in vitro. The reduction of Hsp90α did not influence sensitivity of the colon cancer cells to activators or inhibitors of the Wnt pathway, but rather correlated to reduced TS formation, cell adhesion and spreading, identifying potential therapeutic benefit to the controlled reduction of Hsp90α for the deregulation of colon cancer characteristics. Given that Hsp27 and β-catenin are both involved in cell adhesion, cytoskeletal dynamics and interact directly with each other, we propose a role for targeting Hsp90α in the regulation cell adherence indirectly via reductions in levels of β-catenin and Hsp27, rather than by modifying the transcriptional activity of β-catenin. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2015
- Full Text:
- Date Issued: 2015-04-09
- Authors: Slater, Cindy
- Date: 2015-04-09
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/480345 , vital:78433
- Description: Colon cancers are commonly associated with mutations or changes in signaling in the Wnt/β-catenin pathway. Cancer treatments, such as chemotherapy and radiation, are challenged by the limited methods of disease detection and the insufficient elimination of contributing factors, such as cancer stem-like cells (CSC), to metastatic disease. CSC are characterised by their ability to survive anchorage-independently and attribute to therapeutic resistance. To examine the biological changes associated with the progression of human colon cancers and the role of Hsp90 in cancer and CSC biology, SW480 and SW620 genetically paired (isogenic) colon cancer cell lines from the same patient were characterised for populations of putative CSC, tumoursphere (TS) forming ability, cell growth, behaviour and response to anti-cancer therapeutics. The SW480 cell line was established from a primary colon adenocarcinoma and the SW620 was established from a lymph node metastasis of the primary cancer one year later. To address the role of Hsp90 in colon cancer, the sensitivity of cells and TS were analysed in response to geldanamycin and novobiocin, and an isoform-specific approach to the targeting of Hsp90α was developed. Flow cytometric analysis of putative CSC by phenotype revealed variable proportions of cells bearing the CD44+/CD133+ surface protein marker, widely used in the identification of colon CSC, in SW480 and SW620 cells. The paired cell lines maintained similar proportions of putative CSC, identified by the expression of the ABCG2 protein (side population; 1 %) and through high aldehyde dehydrogenase activity (ALDEFLUOR; 6 %). SW480 cells demonstrated greater TS forming efficiency than SW620 cells (49.9 and 35.5 %, respectively) and observations of wound-healing showed SW480 cells to be more migratory than SW620 cells. No difference in response to Hsp90 inhibition was observed between paired cell lines, however SW480 TS resisted treatment with geldanamycin. This the first study to report a dose-dependent increase in TS growth in response to novobiocin inhibition of Hsp90, and to demonstrate that that the sensitivity of SW480 and SW620 TS to oxaliplatin, a common drug for the treatment of metastatic colon cancers, was enhanced by novobiocin, providing promise for the elimination of CSC with combined chemotherapeutics. We analysed the Wnt/β-catenin pathway in response to expression of short hairpin RNA (shRNA) against Hsp90α or a control non-targeting shRNA, under the control of a tetracycline-responsive promoter. Hsp90α knockdown contributed to a deregulated stress response, presenting with reduced Hsp27 and β-catenin protein, but corresponded to an increase in the association between Hsp90, β-catenin and Hsp27 in vitro. The reduction of Hsp90α did not influence sensitivity of the colon cancer cells to activators or inhibitors of the Wnt pathway, but rather correlated to reduced TS formation, cell adhesion and spreading, identifying potential therapeutic benefit to the controlled reduction of Hsp90α for the deregulation of colon cancer characteristics. Given that Hsp27 and β-catenin are both involved in cell adhesion, cytoskeletal dynamics and interact directly with each other, we propose a role for targeting Hsp90α in the regulation cell adherence indirectly via reductions in levels of β-catenin and Hsp27, rather than by modifying the transcriptional activity of β-catenin. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2015
- Full Text:
- Date Issued: 2015-04-09
Systematics and phylogeography of mormyrid fishes in South Africa
- Authors: Maake, Pholoshi Abram
- Date: 2015-04-09
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/480323 , vital:78431
- Description: Two genera of mormyrids have been reognised from South Africa. Marcuseniusis the largest genus of the Mormyridae, comprising 38 species distributed throughout tropical and sub-tropical Africa. In southern and eastern Africa eight species have been recognized, including M. pongolensis from South Africa. Petrocephalushas about 30 species distributed mainly in tropical Africa, and 15 of these were recently identified in southern and eastern Africa.This thesis integrated several techniques, through the collection of complementary, but separate data sets to investigate the phylogeography of M. pongolensis in South Africa, and the systematics, evolutionary history, biogeography of Marcusenius and Petrocephalusfishes in southern and eastern Africa. Mitochondrial and nuclear genetic markers consistently demonstrated strong population structuring and identified three divergent lineages within South Africa. The widespread Pongola Lineage occurs partly in the Limpopo River system, and is very common in the Incomati, Pongola (type locality) and Kosi river systems. The Limpopo Lineage endemic only in the Limpopo River system is monophyletic with the Mhlatuze-Nseleni Lineage which is only known from the Mhlatuze and Nseleni rivers in the south. There was strong indication of historical isolation, in the form of allopatric fragmentation between genetically divergent Limpopo and Mhlatuze-Nseleni lineages. High genetic diversity was observed in the Limpopo River system within the Limpopo Lineage and the Pongola Lineage. The occurrence of the Mhlatuze-Nseleni Lineage in the far south cannot be explained by the hypothesis of confluence of rivers, river capture or episodic drainage connections, as the Mhlatuze and Nseleni Rivers would not have had a common confluence or shared low relief terrain with the Limpopo, Incomati, Pongola or Kosi river systems. Morphological studies of these lineages revealed even more differentiations and were described as: Marcuseniuskrameri sp. nov. for the Limpopo Lineage, and M. caudisquamatus sp. nov. from the Mhlatuze and Nseleni river systems. The specimens from the Ruvuma River were also well differentiated from all southern and eastern African species of Marcusenius, and were therefore recognised as M. lucombesisp. nov. New diagnosis characters of M. pongolensis were re-described and akey to the southern and eastern African species of Marcuseniuswas also provided. The results of all phylogenetic approaches that included all known southern and eastern AfricanMarcusenius species are highly congruent and provided very strong support for recognizing Marcuseniusspecies from these regions as a monophyletic assemblage that evolved from a single common ancestor. The southern and eastern African Petrocephalus is divided into two deeply mitochondrial and nuclear divergent Western and Eastern groups that are separated by the Victoria Falls. The phylogenetic relationships within each group were not supported and future studies incorporating more molecular characters andspecies will likely help to resolve the relationships. Speciation within Marcusenius and Petrocephalus ranges in the focus of at least 0.8-5 Million years ago in agreement with geological data, which suggested that vicariant events associated with the formation of the major river systems played a major role in the evolution and distribution of both genera in southern and eastern Africa. The high degree of genetic differentiation and at least four previously undescribed lineages recovered in this study suggested that mormyrid diversity within southern and eastern Africa may be underestimated. Possible threats to the studied mormyrid species and lineages and other freshwater-dependent species were identified during the course of this study. When described, the unidentified lineages would further increase the species diversity of both Marcusenius and Petrocephalus,and, therefore, the southern and eastern African ichthyofauna. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2025
- Full Text:
- Date Issued: 2015-04-09
- Authors: Maake, Pholoshi Abram
- Date: 2015-04-09
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/480323 , vital:78431
- Description: Two genera of mormyrids have been reognised from South Africa. Marcuseniusis the largest genus of the Mormyridae, comprising 38 species distributed throughout tropical and sub-tropical Africa. In southern and eastern Africa eight species have been recognized, including M. pongolensis from South Africa. Petrocephalushas about 30 species distributed mainly in tropical Africa, and 15 of these were recently identified in southern and eastern Africa.This thesis integrated several techniques, through the collection of complementary, but separate data sets to investigate the phylogeography of M. pongolensis in South Africa, and the systematics, evolutionary history, biogeography of Marcusenius and Petrocephalusfishes in southern and eastern Africa. Mitochondrial and nuclear genetic markers consistently demonstrated strong population structuring and identified three divergent lineages within South Africa. The widespread Pongola Lineage occurs partly in the Limpopo River system, and is very common in the Incomati, Pongola (type locality) and Kosi river systems. The Limpopo Lineage endemic only in the Limpopo River system is monophyletic with the Mhlatuze-Nseleni Lineage which is only known from the Mhlatuze and Nseleni rivers in the south. There was strong indication of historical isolation, in the form of allopatric fragmentation between genetically divergent Limpopo and Mhlatuze-Nseleni lineages. High genetic diversity was observed in the Limpopo River system within the Limpopo Lineage and the Pongola Lineage. The occurrence of the Mhlatuze-Nseleni Lineage in the far south cannot be explained by the hypothesis of confluence of rivers, river capture or episodic drainage connections, as the Mhlatuze and Nseleni Rivers would not have had a common confluence or shared low relief terrain with the Limpopo, Incomati, Pongola or Kosi river systems. Morphological studies of these lineages revealed even more differentiations and were described as: Marcuseniuskrameri sp. nov. for the Limpopo Lineage, and M. caudisquamatus sp. nov. from the Mhlatuze and Nseleni river systems. The specimens from the Ruvuma River were also well differentiated from all southern and eastern African species of Marcusenius, and were therefore recognised as M. lucombesisp. nov. New diagnosis characters of M. pongolensis were re-described and akey to the southern and eastern African species of Marcuseniuswas also provided. The results of all phylogenetic approaches that included all known southern and eastern AfricanMarcusenius species are highly congruent and provided very strong support for recognizing Marcuseniusspecies from these regions as a monophyletic assemblage that evolved from a single common ancestor. The southern and eastern African Petrocephalus is divided into two deeply mitochondrial and nuclear divergent Western and Eastern groups that are separated by the Victoria Falls. The phylogenetic relationships within each group were not supported and future studies incorporating more molecular characters andspecies will likely help to resolve the relationships. Speciation within Marcusenius and Petrocephalus ranges in the focus of at least 0.8-5 Million years ago in agreement with geological data, which suggested that vicariant events associated with the formation of the major river systems played a major role in the evolution and distribution of both genera in southern and eastern Africa. The high degree of genetic differentiation and at least four previously undescribed lineages recovered in this study suggested that mormyrid diversity within southern and eastern Africa may be underestimated. Possible threats to the studied mormyrid species and lineages and other freshwater-dependent species were identified during the course of this study. When described, the unidentified lineages would further increase the species diversity of both Marcusenius and Petrocephalus,and, therefore, the southern and eastern African ichthyofauna. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2025
- Full Text:
- Date Issued: 2015-04-09
Left-invariant optimal control problems on the Heisenberg group and the associated Hamilton-Poisson systems: classification, stability and integration
- Authors: Bartlett, Catherine Eve
- Date: 2015-04-10
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/480312 , vital:78428
- Description: This thesis examines the left-invariant control affine systems of full rank, evolving on the three-dimensional Heisenberg group H3. Such systems are classified under state space equivalence, detached feedback equivalence and strongly detached feedback equivalence; a complete list of equivalence representatives is obtained. The equivalence of cost-extended control systems corresponding to left-invariant optimal control problems on H3 with fixed terminal time, affine dynamics, and affine quadratic cost is also considered. To left-invariant optimal control problems on H3 with quadratic cost, one may, via the Pontryagin Maximum Principle, associate a quadratic Hamilton-Poisson system on the (minus) Lie-Poisson space h3. Homogeneous and inhomogeneous quadratic Hamilton-Poisson systems are investigated. These systems are classified up to an affine isomorphism. Furthermore, the stability nature of the equilibria of the systems are analysed and explicit expressions for all integral curves are determined. , Thesis (MSc) -- Faculty of Science, Mathematics (Pure and Applied), 2015
- Full Text:
- Date Issued: 2015-04-10
- Authors: Bartlett, Catherine Eve
- Date: 2015-04-10
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/480312 , vital:78428
- Description: This thesis examines the left-invariant control affine systems of full rank, evolving on the three-dimensional Heisenberg group H3. Such systems are classified under state space equivalence, detached feedback equivalence and strongly detached feedback equivalence; a complete list of equivalence representatives is obtained. The equivalence of cost-extended control systems corresponding to left-invariant optimal control problems on H3 with fixed terminal time, affine dynamics, and affine quadratic cost is also considered. To left-invariant optimal control problems on H3 with quadratic cost, one may, via the Pontryagin Maximum Principle, associate a quadratic Hamilton-Poisson system on the (minus) Lie-Poisson space h3. Homogeneous and inhomogeneous quadratic Hamilton-Poisson systems are investigated. These systems are classified up to an affine isomorphism. Furthermore, the stability nature of the equilibria of the systems are analysed and explicit expressions for all integral curves are determined. , Thesis (MSc) -- Faculty of Science, Mathematics (Pure and Applied), 2015
- Full Text:
- Date Issued: 2015-04-10
Use of microbial fuel cells in the beneficiation of algal biomass for bioelectricity production
- Mtambanengwe, Kudzai Tapiwanashe Esau
- Authors: Mtambanengwe, Kudzai Tapiwanashe Esau
- Date: 2015-04-10
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/480334 , vital:78432
- Description: Microbial fuel cells (MFCs) offer an alternative technology that is able to convert organic matter into electrical energy by making use of bacterial biomass as the biocatalysts. Performance of the MFCs is dependent on many factors such as substrate, biocatalyst, electrode material and optimum operational conditions including temperature and pH. Significant research has been conducted on the use of different substrates to fuel the MFC. The possibility of harvesting energy from organic waste sources in the MFC makes the technology attractive. In this study, we have investigated the use of Chlorella, Arthrospira and a mixed algal consortium obtained from the local wastewater treatment facility in Grahamstown, courtesy of the Institute for Environmental Biotechnology, Rhodes University (EBRU) as feedstock in an MFC with Enterobacter cloacae as the biocatalyst. Pre-treatment of the algae-based feedstock was studied as well as the influence of treatment on nutrient release and biocatalyst performance during growth studies and MFC operations. Sonication, autoclaving and a combination of the two were used as the pre-treatment methods. Pre-treatment resulted in the release of nutrients from algal cells to the media. Peak nutrient realease was observed when a combination of sonicating and autoclaving was employed. Sonicating and autoclaving the mixed consortium from EBRU resulted in an MFC peak power density of 101.2 (± 4.58) mW.m-2. This represented more than 80% of the peak power density obtained in RCM medium. Operational conditions during MFC studies such as pH, temperature, nutrient utilisation by the biocatalyst and performance of the proton exchange membrane were measured during the course of the study. Growth kinetics and MFC operations were shown to be optimal when the substrate feedstock was acidic. However, for longer MFC operations (120 hours), total power output was greater by 3 to 5 fold when the feedstock was at acidic pH (4-6) than when the pH of the substrate feedstock was alkaline (8 and 9). Further MFC studies were performed on the effect of electrode materials including activated carbon fibre and carbon paper. The study examined also the use of live Chlorella and Arthrospira cultures as biocathodes in an MFC. We also showed that activated carbon fibre performs well as an electrode catalyst for both anode and cathode without any need of modification. Biocathode studies showed that the main limiting factor to biocathodes performance was light irradiance. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2015
- Full Text:
- Date Issued: 2015-04-10
- Authors: Mtambanengwe, Kudzai Tapiwanashe Esau
- Date: 2015-04-10
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/480334 , vital:78432
- Description: Microbial fuel cells (MFCs) offer an alternative technology that is able to convert organic matter into electrical energy by making use of bacterial biomass as the biocatalysts. Performance of the MFCs is dependent on many factors such as substrate, biocatalyst, electrode material and optimum operational conditions including temperature and pH. Significant research has been conducted on the use of different substrates to fuel the MFC. The possibility of harvesting energy from organic waste sources in the MFC makes the technology attractive. In this study, we have investigated the use of Chlorella, Arthrospira and a mixed algal consortium obtained from the local wastewater treatment facility in Grahamstown, courtesy of the Institute for Environmental Biotechnology, Rhodes University (EBRU) as feedstock in an MFC with Enterobacter cloacae as the biocatalyst. Pre-treatment of the algae-based feedstock was studied as well as the influence of treatment on nutrient release and biocatalyst performance during growth studies and MFC operations. Sonication, autoclaving and a combination of the two were used as the pre-treatment methods. Pre-treatment resulted in the release of nutrients from algal cells to the media. Peak nutrient realease was observed when a combination of sonicating and autoclaving was employed. Sonicating and autoclaving the mixed consortium from EBRU resulted in an MFC peak power density of 101.2 (± 4.58) mW.m-2. This represented more than 80% of the peak power density obtained in RCM medium. Operational conditions during MFC studies such as pH, temperature, nutrient utilisation by the biocatalyst and performance of the proton exchange membrane were measured during the course of the study. Growth kinetics and MFC operations were shown to be optimal when the substrate feedstock was acidic. However, for longer MFC operations (120 hours), total power output was greater by 3 to 5 fold when the feedstock was at acidic pH (4-6) than when the pH of the substrate feedstock was alkaline (8 and 9). Further MFC studies were performed on the effect of electrode materials including activated carbon fibre and carbon paper. The study examined also the use of live Chlorella and Arthrospira cultures as biocathodes in an MFC. We also showed that activated carbon fibre performs well as an electrode catalyst for both anode and cathode without any need of modification. Biocathode studies showed that the main limiting factor to biocathodes performance was light irradiance. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2015
- Full Text:
- Date Issued: 2015-04-10
Determination of speaker configuration for an immersive audio content creation system
- Authors: Lebusa, Motebang
- Date: 2020
- Subjects: Loudspeakers , Surround-sound systems , Algorithms , Coordinates
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/163375 , vital:41034
- Description: Various spatialisation algorithms require the knowledge of speaker locations to accurately localise sound in 3D environments. The rendering process uses speaker coordinates to feed into their algorithms so that they can render the immersive audio content as intended by an artist. The need to measure the loudspeaker coordinates becomes necessary, especially in environments where the speaker layouts change frequently. Manually measuring the coordinates, however, tends to be a laborious task that is prone to errors. This research provides an automated solution to the problem of speaker coordinates measurement. The solution system, SDIAS, is a client-server system that uses the capabilities provided by the Ethernet Audio Video Bridging standard to measure the 3D loudspeaker coordinates for immersive sound systems. SDIAS deploys commodity hardware and readily available software to implement the solution. A server sends a short tone to each speaker in the speaker configuration, at equal intervals. A microphone attached to a mobile device picks up these transmitted tones on the client side, from different locations. The transmission and reception times from both components of the system are used to measure the time of flight for each tone sent to a loudspeaker. These are then used to determine the 3D coordinates of each loudspeaker in the available layout. Tests were performed to determine the accuracy of the determination algorithm for SDIAS, and were compared to the manually measured coordinates. , Thesis (MSc) -- Faculty of Science, Computer Science, 2020
- Full Text:
- Date Issued: 2020
- Authors: Lebusa, Motebang
- Date: 2020
- Subjects: Loudspeakers , Surround-sound systems , Algorithms , Coordinates
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/163375 , vital:41034
- Description: Various spatialisation algorithms require the knowledge of speaker locations to accurately localise sound in 3D environments. The rendering process uses speaker coordinates to feed into their algorithms so that they can render the immersive audio content as intended by an artist. The need to measure the loudspeaker coordinates becomes necessary, especially in environments where the speaker layouts change frequently. Manually measuring the coordinates, however, tends to be a laborious task that is prone to errors. This research provides an automated solution to the problem of speaker coordinates measurement. The solution system, SDIAS, is a client-server system that uses the capabilities provided by the Ethernet Audio Video Bridging standard to measure the 3D loudspeaker coordinates for immersive sound systems. SDIAS deploys commodity hardware and readily available software to implement the solution. A server sends a short tone to each speaker in the speaker configuration, at equal intervals. A microphone attached to a mobile device picks up these transmitted tones on the client side, from different locations. The transmission and reception times from both components of the system are used to measure the time of flight for each tone sent to a loudspeaker. These are then used to determine the 3D coordinates of each loudspeaker in the available layout. Tests were performed to determine the accuracy of the determination algorithm for SDIAS, and were compared to the manually measured coordinates. , Thesis (MSc) -- Faculty of Science, Computer Science, 2020
- Full Text:
- Date Issued: 2020
Exploring pre-service teachers’ reflective practice in the context of video-based lesson analysis
- Authors: Chikiwa, Samukeliso
- Date: 2020-04-30
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/355357 , vital:64492
- Description: This study explored the development of reflective practice in foundation phase pre-service teachers in the context of video-based lesson analysis at a university in South Africa. The study was conducted in the field of mathematics education, responding to the urgent need to equip pre-service South African teachers with the knowledge and skills for effective mathematics teaching. The research is foregrounded by the continuing poor performance of South African learners in mathematics at all levels of education in the country, which has been linked to the inadequate knowledge and skills of mathematics teachers. Pre-service teacher education is putting considerable effort into improving the preparation of mathematics teachers and developing their ability to reflect on their teaching practice is one of the strategies being employed for this purpose. Research has demonstrated the importance of reflective practice (RP) in both developing and extending teachers’ mathematical knowledge for teaching. This study therefore contributes to current research that supports the development of RP as a professional skill for promoting the acquisition of knowledge for teaching in pre-service teacher education. The study adopted a qualitative case study approach with two phases of data collection. In Phase 1 I collected and analysed three sets of 19 pre-service teachers’ written reflections to establish the nature of the reflections that they developed when analysing video-recorded mathematics lessons of experienced teachers’ practice. Phase 2 was conducted with four PSTs who reflected on video-recorded mathematics lessons of their own practice, and similarly sought to investigate the nature of the reflections they developed when reflecting on practice. The four PSTs wrote one set of reflections on their own lessons, went through three sessions of facilitator-guided reflections, then wrote another set of reflections to establish if the support provided in small group facilitator-guided sessions improved their reflections. Iterative content analysis was employed to analyse the PSTs’ written reflections, using an analytic tool that I developed for this purpose through merging Lee’s (2007) and Muir and Beswick’s (2007) levels of reflection frameworks. My model had four levels of reflection: description, explanation, suggestion and reflectivity. The names of each of the levels connect to the key indicator for that level. PSTs’ written reflections were coded and analysed according to these levels. The study found that PSTs’ initial reflections were mostly description of general classroom events with little reflection at the levels of explanation and suggestion, and an absence of reflectivity. Most reflections focused on general events in the lesson rather than mathematical events, even though the six lens framework they were given to guide their reflections prompted them to steer their attention towards mathematical events. The second and third sets of reflections, although mostly still at level 1, showed some shifts towards explanation and suggestion, although an increased focus on mathematical events though reflectivity was still largely absent. No PST reached the fourth level of reflectivity in Phase 1. However, in Phase 2, the PSTs’ reflections after the three small group facilitator-guided sessions included some evidence of reflectivity. The findings suggest the need for pre-service teacher educators to make a concerted effort to teach PSTs what reflection is and how to reflect on their practice. The findings also showed the need for small group facilitator-guided support in the development of PSTs’ reflective practice. , Thesis (PhD) -- Faculty of Education, Education, 2020
- Full Text:
- Date Issued: 2020-04-30
- Authors: Chikiwa, Samukeliso
- Date: 2020-04-30
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/355357 , vital:64492
- Description: This study explored the development of reflective practice in foundation phase pre-service teachers in the context of video-based lesson analysis at a university in South Africa. The study was conducted in the field of mathematics education, responding to the urgent need to equip pre-service South African teachers with the knowledge and skills for effective mathematics teaching. The research is foregrounded by the continuing poor performance of South African learners in mathematics at all levels of education in the country, which has been linked to the inadequate knowledge and skills of mathematics teachers. Pre-service teacher education is putting considerable effort into improving the preparation of mathematics teachers and developing their ability to reflect on their teaching practice is one of the strategies being employed for this purpose. Research has demonstrated the importance of reflective practice (RP) in both developing and extending teachers’ mathematical knowledge for teaching. This study therefore contributes to current research that supports the development of RP as a professional skill for promoting the acquisition of knowledge for teaching in pre-service teacher education. The study adopted a qualitative case study approach with two phases of data collection. In Phase 1 I collected and analysed three sets of 19 pre-service teachers’ written reflections to establish the nature of the reflections that they developed when analysing video-recorded mathematics lessons of experienced teachers’ practice. Phase 2 was conducted with four PSTs who reflected on video-recorded mathematics lessons of their own practice, and similarly sought to investigate the nature of the reflections they developed when reflecting on practice. The four PSTs wrote one set of reflections on their own lessons, went through three sessions of facilitator-guided reflections, then wrote another set of reflections to establish if the support provided in small group facilitator-guided sessions improved their reflections. Iterative content analysis was employed to analyse the PSTs’ written reflections, using an analytic tool that I developed for this purpose through merging Lee’s (2007) and Muir and Beswick’s (2007) levels of reflection frameworks. My model had four levels of reflection: description, explanation, suggestion and reflectivity. The names of each of the levels connect to the key indicator for that level. PSTs’ written reflections were coded and analysed according to these levels. The study found that PSTs’ initial reflections were mostly description of general classroom events with little reflection at the levels of explanation and suggestion, and an absence of reflectivity. Most reflections focused on general events in the lesson rather than mathematical events, even though the six lens framework they were given to guide their reflections prompted them to steer their attention towards mathematical events. The second and third sets of reflections, although mostly still at level 1, showed some shifts towards explanation and suggestion, although an increased focus on mathematical events though reflectivity was still largely absent. No PST reached the fourth level of reflectivity in Phase 1. However, in Phase 2, the PSTs’ reflections after the three small group facilitator-guided sessions included some evidence of reflectivity. The findings suggest the need for pre-service teacher educators to make a concerted effort to teach PSTs what reflection is and how to reflect on their practice. The findings also showed the need for small group facilitator-guided support in the development of PSTs’ reflective practice. , Thesis (PhD) -- Faculty of Education, Education, 2020
- Full Text:
- Date Issued: 2020-04-30
Gender bias in the field of economics: an analysis of South African academia
- Authors: Hitchcock, Siobhan
- Date: 2020-10-30
- Subjects: Sexism South Africa , Sexism in higher education South Africa , Economics Study and teaching (Higher) South Africa , Economics teachers South Africa , Women in higher education South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/366275 , vital:65850
- Description: In recent years there has been a growing focus internationally on the low participation of females in Economics, both in academia and business. While female enrolment in higher education, including other maths-based subjects, has grown substantially, this has not been the case for Economics. Economics, particularly as one progresses through postgraduate studies to doctoral degrees now stands out as an outlier. A number of reasons have been advanced for this, including the nature of the subject, the type of people it attracts and the lack of female role models. Male and female enrolments in South African HEIs have grown between 2007 and 2017, but females have grown at a faster rate, thus increasing the female share of total enrolments to 59%. Female students are more successful and so make up an even greater proportion of South African graduates. Female enrolments and graduates are also higher than in the US. As in the US there is a significant drop off in female representation when progressing from undergraduate to postgraduate studies in South Africa. When looking at Economics in South Africa in comparison to the broad CESM categories, female enrolment in Economics Bachelor degrees is significantly lower than in Business and Humanities, but on a par with STEM subjects. At the Doctoral level, there are sharp drop offs in female enrolments for all categories. Business and Economics are the laggards at the Doctoral level, below STEM and Humanities. Furthermore, females make up a minority of academic staff in South African HEIs, with males dominating in especially the higher academic ranks. As one moves up the academic ladder, the female share decreases. This research analyses gender compositions of staff and students at South African HEIs. National data are obtained from government publications and data relating to four specific South African universities was obtained directly from the universities. Questionnaires were sent to a sample of academic staff and students who are in the field of economics to identify whether there is a role model effect for economics students and whether female academics experience the same forms of biases, discrimination, or treatment as that identified in international studies. It was concluded that while there are drop offs in the overall female representation of students at the Masters and Doctoral levels in South Africa, this share is gradually increasing. Additionally, Economics seems to perform better than what is depicted in the US, and in comparison to some STEM subjects in South Africa. Furthermore, the environment within the field of academic economics for both female students and staff seems to be more positive than what the international literature depicts for the US. But there are nonetheless different levels of satisfaction between male and female academic economists. While the student surveys revealed that female Economics students do not attach great importance to female role models, there is some evidence of correlation between the percentage of female professors and the percentage of female PhD students across a range of STEM subjects in South Africa. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2020
- Full Text:
- Date Issued: 2020-10-30
- Authors: Hitchcock, Siobhan
- Date: 2020-10-30
- Subjects: Sexism South Africa , Sexism in higher education South Africa , Economics Study and teaching (Higher) South Africa , Economics teachers South Africa , Women in higher education South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/366275 , vital:65850
- Description: In recent years there has been a growing focus internationally on the low participation of females in Economics, both in academia and business. While female enrolment in higher education, including other maths-based subjects, has grown substantially, this has not been the case for Economics. Economics, particularly as one progresses through postgraduate studies to doctoral degrees now stands out as an outlier. A number of reasons have been advanced for this, including the nature of the subject, the type of people it attracts and the lack of female role models. Male and female enrolments in South African HEIs have grown between 2007 and 2017, but females have grown at a faster rate, thus increasing the female share of total enrolments to 59%. Female students are more successful and so make up an even greater proportion of South African graduates. Female enrolments and graduates are also higher than in the US. As in the US there is a significant drop off in female representation when progressing from undergraduate to postgraduate studies in South Africa. When looking at Economics in South Africa in comparison to the broad CESM categories, female enrolment in Economics Bachelor degrees is significantly lower than in Business and Humanities, but on a par with STEM subjects. At the Doctoral level, there are sharp drop offs in female enrolments for all categories. Business and Economics are the laggards at the Doctoral level, below STEM and Humanities. Furthermore, females make up a minority of academic staff in South African HEIs, with males dominating in especially the higher academic ranks. As one moves up the academic ladder, the female share decreases. This research analyses gender compositions of staff and students at South African HEIs. National data are obtained from government publications and data relating to four specific South African universities was obtained directly from the universities. Questionnaires were sent to a sample of academic staff and students who are in the field of economics to identify whether there is a role model effect for economics students and whether female academics experience the same forms of biases, discrimination, or treatment as that identified in international studies. It was concluded that while there are drop offs in the overall female representation of students at the Masters and Doctoral levels in South Africa, this share is gradually increasing. Additionally, Economics seems to perform better than what is depicted in the US, and in comparison to some STEM subjects in South Africa. Furthermore, the environment within the field of academic economics for both female students and staff seems to be more positive than what the international literature depicts for the US. But there are nonetheless different levels of satisfaction between male and female academic economists. While the student surveys revealed that female Economics students do not attach great importance to female role models, there is some evidence of correlation between the percentage of female professors and the percentage of female PhD students across a range of STEM subjects in South Africa. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2020
- Full Text:
- Date Issued: 2020-10-30
Creative Cities and Regional Development: the Case of Makhanda and the Creative City Project
- Authors: Campbell, Guy John
- Date: 2021
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/174448 , vital:42478
- Description: The ‘Creative City’ is a popular term describing a method of regional/urban development through the development of creative and cultural industries (CCIs). Research into this topic has mostly focused on large cities in developed nations. Research into its applicability to small, underdeveloped regions located in developing nations has been severely limited. This research drew on the creative city theory of Richard Florida (2002) and other relevant literature in the realm of creative and cultural economics. The extent to which the ‘Creative City’ Project of Makhanda, located in the Eastern Cape Province of South Africa, was successful in meeting its stated goals was assessed. The institutional frameworks and operational context of the project were investigated. A mixed-methods approach was applied. This included qualitative research techniques, drawing from multiple international and national case studies and literature. It also involved interviews with key stakeholders involved with the project. A quantitative survey assessed the extent to which the project has been successful in its goal to market Makhanda as the “Creative City” and whether it could become “South Africa’s Creative and Cultural Capital”. There is no reliable standard blueprint for how to develop a creative city. However, factors for success can be found in the development of new and growing creative spaces for the centralisation of creative and cultural activity; in associated employment opportunities and industry experience made available; and in strong partnerships forged between the project, local government and a range of key stakeholders. The Makhanda project faced significant challenges – namely, scarce financial support, small local consumer markets, an insufficiently recognised brand, limited support from local business and no vertical alignment with the national policy agenda. Despite the challenges several advantages were identified, including; a generous endowment in hard and soft infrastructures, a socially diverse and open environment, and a project rooted in the community interest. The project exhibits the potential to develop a thriving arts and culture sector in Makhanda. But it will be critical for the project to become self-sufficient and remain, and further embed itself, in the interests of the broad community for whom the project ultimately aims to benefit. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
- Full Text:
- Date Issued: 2021
- Authors: Campbell, Guy John
- Date: 2021
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/174448 , vital:42478
- Description: The ‘Creative City’ is a popular term describing a method of regional/urban development through the development of creative and cultural industries (CCIs). Research into this topic has mostly focused on large cities in developed nations. Research into its applicability to small, underdeveloped regions located in developing nations has been severely limited. This research drew on the creative city theory of Richard Florida (2002) and other relevant literature in the realm of creative and cultural economics. The extent to which the ‘Creative City’ Project of Makhanda, located in the Eastern Cape Province of South Africa, was successful in meeting its stated goals was assessed. The institutional frameworks and operational context of the project were investigated. A mixed-methods approach was applied. This included qualitative research techniques, drawing from multiple international and national case studies and literature. It also involved interviews with key stakeholders involved with the project. A quantitative survey assessed the extent to which the project has been successful in its goal to market Makhanda as the “Creative City” and whether it could become “South Africa’s Creative and Cultural Capital”. There is no reliable standard blueprint for how to develop a creative city. However, factors for success can be found in the development of new and growing creative spaces for the centralisation of creative and cultural activity; in associated employment opportunities and industry experience made available; and in strong partnerships forged between the project, local government and a range of key stakeholders. The Makhanda project faced significant challenges – namely, scarce financial support, small local consumer markets, an insufficiently recognised brand, limited support from local business and no vertical alignment with the national policy agenda. Despite the challenges several advantages were identified, including; a generous endowment in hard and soft infrastructures, a socially diverse and open environment, and a project rooted in the community interest. The project exhibits the potential to develop a thriving arts and culture sector in Makhanda. But it will be critical for the project to become self-sufficient and remain, and further embed itself, in the interests of the broad community for whom the project ultimately aims to benefit. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
- Full Text:
- Date Issued: 2021
Maternal health care services in waiting mothers’ shelters: the case of Mawadza village in Bonda, Manicaland, Zimbabwe
- Authors: Muchabveyo, Brenda Hamufari
- Date: 2021
- Subjects: Pregnant women Zimbabwe Manicaland Province , Women's shelters Zimbabwe Manicaland Province , Maternal health services Zimbabwe Manicaland Province , Integrative medicine , Childbirth Social aspects Zimbabwe Manicaland Province
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/476912 , vital:78017 , DOI 10.21504/10962/476912
- Description: This study explores the experiences and perceptions of expectant mothers during prenatal, intra-, and postpartum care. It focuses on expectant mother‘s use or non-use of a waiting mothers' shelter within a medical pluralistic village within a context where hospitals and maternal health care facilities are not proximate. Special focus was on Mawadza village in the Mutasa district in Manicaland Province of Zimbabwe. A sample of 48 participants was used for collecting data in this study. The sample consisted of 15 women some of whom were expectant mothers in the waiting mothers‘ shelter (11) and others had used (4) the shelter once or twice since 2015. Participants were drawn mainly from Mawadza village and Bonda Mission Hospital while others were from the district and provincial offices of the Ministry of Health and Child Care of Zimbabwe. The study adopted a qualitative research methodology, which employed in-depth interviews; key informant interviews (KIIs) and focus group discussions (FGDs) as the main data gathering strategies. In-depth interviews were conducted with the expectant mothers and those who had formerly used the shelter since 2015, while, key informant interviews were conducted with the hospital staff members, traditional healers and the midwives from Mawadza village. Focus group discussions were also conducted with both male and female community members from Mawadza village. The study carried out face to face interviews and notes were handwritten and transcribed at the end of each day. Data coding was used to analyse data. The paradigms and theoretical underpinnings of the study were influenced by the symbolic interactionist theory. The theory made it possible to understand the social processes of pregnancy and childbirth in the waiting mothers' shelter due to its interpretive approach to social research and the legitimacy it places on the social interaction and meanings that social actors place on interactions in their environments. The study documented the ways pregnancy and childbirth are perceived, understood, and experienced in Mawadza village within the context of medical pluralism. In Mawadza village, pregnancy and childbirth are highly embedded in the cultural beliefs of the local people, hence, treated with importance and assumed important symbolic meanings. On the contrary, the waiting mothers‘ shelter as a biomedical facility handles pregnancy and childbirth from a biomedical approach, basing its practices and operations on pure science. Expectant mothers who await labour in this facility are therefore involved in several biomedical activities during prenatal, intra- and post-partum care in the waiting mothers‘ shelter. The need to access skilled birth attendants and the criminalisation of home births in Mawadza village have been the major reasons that influence the expectant mothers to use the waiting mothers‘ shelter. Nevertheless, factors such as medical pluralism, child care, and family commitments, lack of understanding of the importance of the waiting mothers‘ shelter, lack of privacy in the shelter, and cost of food and utilities during the expectant mothers' stay in this facility among others are factors that deter expectant mothers from using the waiting mothers' shelter. Lack of practice of bodily agency where practices common in preparation for childbirth such as opening the birth canal which is not accepted was also reported among common problems that discourage expectant mothers from preferring use of the shelters. The study also revealed that the community is involved in the operations of the waiting mothers‘ shelter, although, the involvement is gendered since there are more women involved as compared to men. The study concluded that even biological processes such as pregnancy and childbirth can only be fully understood within a social context given the different meanings which are attached to the various aspects of the childbirth process by the various actors such as expectant mothers, mothers, biomedical practitioners, traditional healers and communities in Mawadza village. Also, in a medical pluralistic village, the different health care providers who deal with pregnant women do not necessarily conflict as evidenced by the complementary role of these two (complementary insofar as they achieve collectively desired outcomes, albeit in parallel and (mutually) exclusive means) in caring for women during pregnancy and childbirth. , Thesis (PhD) -- Faculty of Humanities, Sociology, 2021
- Full Text:
- Date Issued: 2021
- Authors: Muchabveyo, Brenda Hamufari
- Date: 2021
- Subjects: Pregnant women Zimbabwe Manicaland Province , Women's shelters Zimbabwe Manicaland Province , Maternal health services Zimbabwe Manicaland Province , Integrative medicine , Childbirth Social aspects Zimbabwe Manicaland Province
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/476912 , vital:78017 , DOI 10.21504/10962/476912
- Description: This study explores the experiences and perceptions of expectant mothers during prenatal, intra-, and postpartum care. It focuses on expectant mother‘s use or non-use of a waiting mothers' shelter within a medical pluralistic village within a context where hospitals and maternal health care facilities are not proximate. Special focus was on Mawadza village in the Mutasa district in Manicaland Province of Zimbabwe. A sample of 48 participants was used for collecting data in this study. The sample consisted of 15 women some of whom were expectant mothers in the waiting mothers‘ shelter (11) and others had used (4) the shelter once or twice since 2015. Participants were drawn mainly from Mawadza village and Bonda Mission Hospital while others were from the district and provincial offices of the Ministry of Health and Child Care of Zimbabwe. The study adopted a qualitative research methodology, which employed in-depth interviews; key informant interviews (KIIs) and focus group discussions (FGDs) as the main data gathering strategies. In-depth interviews were conducted with the expectant mothers and those who had formerly used the shelter since 2015, while, key informant interviews were conducted with the hospital staff members, traditional healers and the midwives from Mawadza village. Focus group discussions were also conducted with both male and female community members from Mawadza village. The study carried out face to face interviews and notes were handwritten and transcribed at the end of each day. Data coding was used to analyse data. The paradigms and theoretical underpinnings of the study were influenced by the symbolic interactionist theory. The theory made it possible to understand the social processes of pregnancy and childbirth in the waiting mothers' shelter due to its interpretive approach to social research and the legitimacy it places on the social interaction and meanings that social actors place on interactions in their environments. The study documented the ways pregnancy and childbirth are perceived, understood, and experienced in Mawadza village within the context of medical pluralism. In Mawadza village, pregnancy and childbirth are highly embedded in the cultural beliefs of the local people, hence, treated with importance and assumed important symbolic meanings. On the contrary, the waiting mothers‘ shelter as a biomedical facility handles pregnancy and childbirth from a biomedical approach, basing its practices and operations on pure science. Expectant mothers who await labour in this facility are therefore involved in several biomedical activities during prenatal, intra- and post-partum care in the waiting mothers‘ shelter. The need to access skilled birth attendants and the criminalisation of home births in Mawadza village have been the major reasons that influence the expectant mothers to use the waiting mothers‘ shelter. Nevertheless, factors such as medical pluralism, child care, and family commitments, lack of understanding of the importance of the waiting mothers‘ shelter, lack of privacy in the shelter, and cost of food and utilities during the expectant mothers' stay in this facility among others are factors that deter expectant mothers from using the waiting mothers' shelter. Lack of practice of bodily agency where practices common in preparation for childbirth such as opening the birth canal which is not accepted was also reported among common problems that discourage expectant mothers from preferring use of the shelters. The study also revealed that the community is involved in the operations of the waiting mothers‘ shelter, although, the involvement is gendered since there are more women involved as compared to men. The study concluded that even biological processes such as pregnancy and childbirth can only be fully understood within a social context given the different meanings which are attached to the various aspects of the childbirth process by the various actors such as expectant mothers, mothers, biomedical practitioners, traditional healers and communities in Mawadza village. Also, in a medical pluralistic village, the different health care providers who deal with pregnant women do not necessarily conflict as evidenced by the complementary role of these two (complementary insofar as they achieve collectively desired outcomes, albeit in parallel and (mutually) exclusive means) in caring for women during pregnancy and childbirth. , Thesis (PhD) -- Faculty of Humanities, Sociology, 2021
- Full Text:
- Date Issued: 2021
Land use decision-making on residential plots in Fingo Village, Makhanda (Grahamstown), South Africa
- Authors: Memela, Sinenhlanhla
- Date: 2021-04-28
- Subjects: Land use South Africa Makhanda Decision making , Land use, Urban South Africa Makhanda Decision making , Residential real estate South Africa Makhanda , Urban ecology (Sociology) South Africa Makhanda , Urban gardening South Africa Makhanda , Urban livestock production systems South Africa Makhanda
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/322694 , vital:60589 , DOI 10.21504/10962/322694
- Description: This study seeks to understand land use decision-making dynamics on large residential plots in Fingo Village, Makhanda (Grahamstown). Fingo Village was selected as a study area because it is one of the poorest urban settings in South Africa where urban poverty is observed alongside access to land. A dominant economic perspective not only suggests that land use decisions are motivated by economic motives, but also implies that access to land would enable people to generate income from its use to improve their livelihoods. This study argues against an uncritical embrace of this assumption. Lefebvre’s production of space thesis provides a holistic understanding of the factors involved in the making of land use decisions. The focus of this study is on the dialectic process in the spatial triad– spatial practice, representational space and representations of space. This involved the reading of government policies and legislation together with local lived experiences to gain an understanding of the particular spatial practices seen in Fingo Village. Snowball and convenience sampling were used to select 36 household plots in Fingo Village. Primary data was gathered by means of semi-structured interviews and participatory mapping while additional information was sourced from secondary sources and desktop analysis. The findings of the study show that there is no uniform pattern of land use and success. Different land use activities found on the selected residential plots, including the main house, backyard flat or flats, spaza shops, a funeral parlour, livestock keeping, cultural use (a kraal for ancestral worship) and food gardening. These activities are motivated by residents’ perceptions and attitudes towards their spaces, as well as the value and meaning they attach to the land which is not limited to economic factors, but is also influenced by socio-cultural, political and biophysical considerations. Although some spatial practices are prohibited by the government, they are important to the residents. Other participants fail to use the land as would be expected by a conventional economic perspective, due to spatial conflict relating to different interests as a result of collective land ownership and the failure of municipalities to enforce policies and regulations. The fact that numerous factors influence households’ land use decisions means that access to land does not always directly translate into economic benefits. It is all about what people think or do about their land, as well as what the state lays out in terms of policy and legislation, that will influence whether those people with large plots of land will ‘prosper’ or not. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
- Date Issued: 2021-04-28
Land use decision-making on residential plots in Fingo Village, Makhanda (Grahamstown), South Africa
- Authors: Memela, Sinenhlanhla
- Date: 2021-04-28
- Subjects: Land use South Africa Makhanda Decision making , Land use, Urban South Africa Makhanda Decision making , Residential real estate South Africa Makhanda , Urban ecology (Sociology) South Africa Makhanda , Urban gardening South Africa Makhanda , Urban livestock production systems South Africa Makhanda
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/322694 , vital:60589 , DOI 10.21504/10962/322694
- Description: This study seeks to understand land use decision-making dynamics on large residential plots in Fingo Village, Makhanda (Grahamstown). Fingo Village was selected as a study area because it is one of the poorest urban settings in South Africa where urban poverty is observed alongside access to land. A dominant economic perspective not only suggests that land use decisions are motivated by economic motives, but also implies that access to land would enable people to generate income from its use to improve their livelihoods. This study argues against an uncritical embrace of this assumption. Lefebvre’s production of space thesis provides a holistic understanding of the factors involved in the making of land use decisions. The focus of this study is on the dialectic process in the spatial triad– spatial practice, representational space and representations of space. This involved the reading of government policies and legislation together with local lived experiences to gain an understanding of the particular spatial practices seen in Fingo Village. Snowball and convenience sampling were used to select 36 household plots in Fingo Village. Primary data was gathered by means of semi-structured interviews and participatory mapping while additional information was sourced from secondary sources and desktop analysis. The findings of the study show that there is no uniform pattern of land use and success. Different land use activities found on the selected residential plots, including the main house, backyard flat or flats, spaza shops, a funeral parlour, livestock keeping, cultural use (a kraal for ancestral worship) and food gardening. These activities are motivated by residents’ perceptions and attitudes towards their spaces, as well as the value and meaning they attach to the land which is not limited to economic factors, but is also influenced by socio-cultural, political and biophysical considerations. Although some spatial practices are prohibited by the government, they are important to the residents. Other participants fail to use the land as would be expected by a conventional economic perspective, due to spatial conflict relating to different interests as a result of collective land ownership and the failure of municipalities to enforce policies and regulations. The fact that numerous factors influence households’ land use decisions means that access to land does not always directly translate into economic benefits. It is all about what people think or do about their land, as well as what the state lays out in terms of policy and legislation, that will influence whether those people with large plots of land will ‘prosper’ or not. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
- Date Issued: 2021-04-28
Academic distress & disordered eating in students during the Covid-19 pandemic: a cross-sectional study at a South African university
- Authors: Du Toit, Mae
- Date: 2021-10-29
- Subjects: COVID-19 Pandemic, 2020- Influence , Eating disorders , College students Attitudes , College students Mental health , Stress (Psychology)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/192626 , vital:45244
- Description: University students are at risk for reduced mental wellbeing, particularly during the Covid-19 pandemic, and among the most common problems experienced are academic distress and eating concerns. Through a stress-coping model lens, a link between academic distress and disordered eating in student populations appears possible but has not previously been explored. The present study examines this relationship in a South African undergraduate sample. Data were collected during the Covid-19 pandemic using a cross-sectional, correlational survey design and the Counseling Center Assessment of Psychological Symptoms (CCAPS). The results of a multiple regression analysis indicate that academic distress most strongly predicts eating concerns, followed by the demographic variables of female gender and black racial identification. This novel finding suggests that academic institutions should consider the broader academic environment as point of intervention for the prevention and treatment of disordered eating in students. , Thesis (MA) -- Faculty of Humanities, Psychology, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Du Toit, Mae
- Date: 2021-10-29
- Subjects: COVID-19 Pandemic, 2020- Influence , Eating disorders , College students Attitudes , College students Mental health , Stress (Psychology)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/192626 , vital:45244
- Description: University students are at risk for reduced mental wellbeing, particularly during the Covid-19 pandemic, and among the most common problems experienced are academic distress and eating concerns. Through a stress-coping model lens, a link between academic distress and disordered eating in student populations appears possible but has not previously been explored. The present study examines this relationship in a South African undergraduate sample. Data were collected during the Covid-19 pandemic using a cross-sectional, correlational survey design and the Counseling Center Assessment of Psychological Symptoms (CCAPS). The results of a multiple regression analysis indicate that academic distress most strongly predicts eating concerns, followed by the demographic variables of female gender and black racial identification. This novel finding suggests that academic institutions should consider the broader academic environment as point of intervention for the prevention and treatment of disordered eating in students. , Thesis (MA) -- Faculty of Humanities, Psychology, 2021
- Full Text:
- Date Issued: 2021-10-29
Characterisation of the ultramafic and carbonatite components of the Schiel Alkaline Complex in the Limpopo Province of South Africa
- Authors: Mahomed, Uzayr
- Date: 2021-10-29
- Subjects: Ultrabasic rocks South Africa Limpopo , Carbonatites South Africa Limpopo , Geology South Africa Limpopo , Mica South Africa Limpopo , Biotite South Africa Limpopo , Magmatism , Schiel Alkaline Complex , Phoscorite , Glimmerite
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/294768 , vital:57253
- Description: Owing to the poor documentation of the phoscorite-carbonatite association present in the Schiel Complex and the associated economic potential of other known phoscorite-bearing complexes, the Schiel Complex is widely thought to have similar economic potential. This complex is often compared to the lucrative Phalaborwa Complex, as it is thought to have crystallised from a common parental melt, with a similar age of emplacement. This study aims to provide clarity on the physical and chemical characterisation of the various rock types present in the Schiel Complex, with this study being the first petrological investigation based on fresh in-situ samples gathered from 3 borehole cores which were drilled by FOSKOR in the 1960s. The sampled sections of the ultramafics from the Schiel Complex are comprised of end-member rock compositions of either magmatic phoscorites or pyroxenites or metasomatic glimmerites, where gradational contacts between these various end-members produce rock varieties that contain characteristics of one or more end-member types. Carbonatite rocks are present as medium-grained, coarse-grained and banded calcio-carbonatite varieties where the carbonatite rocks are proposed as being the metasomatic medium for glimmerite production. Contrary to previous research, the structure of the ultramafic and carbonatite bodies are present as vein and veinlet structures which seem to originate from a single pipe-like body, from which these rock types intruded into the surrounding syenitic country-rock. Metasomatic alteration of the ultramafic sections of the Schiel Complex also show that the carbonatite rocks must have intruded after some ultramafic magmatism. The presence of the same minerals, with similar chemistries, in both the ultramafic and carbonatite rocks as well as similar REE chondrite-normalised plots show that the various rock types may have originated from a common parental magma, where the accumulation and crystallisation of minerals is the most likely factor in producing the various Schiel Complex rock varieties, causing silicate minerals to be present in the carbonate fraction of the magma, and carbonate minerals in the silicate fraction of the magma. Apatite is the expected rare earth element (REE) mineralising mineral in phoscorites, but is shown to be depleted in REE content in the Schiel Complex due to metasomatic fluid infiltration causing the scavenging and dissipation of REEs. These rocks have also crystallised containing no significant copper-bearing mineralisation, contrary to that which is seen in the Phalaborwa Complex. A comparison of mica minerals between the Schiel Complex rocks and the Phalaborwa Complex rocks show that the two complexes have undergone unique emplacement processes and should not be considered as sister complexes. Efforts to date the glimmerite and carbonatite rocks based on zircon grain U/Pb geochronology proved unsuccessful in constraining the current ages of emplacement provided by previous researchers, but rock relationships show that the current accepted sequence of events cannot be correct, providing scope for further research. This study provides an update on the chemical and physical characteristics, based on the only available sample suite of the ultramafic and carbonatite components, of the Schiel Complex, increasing the depth of documentation of these rare rock types and aiding in refuting some conclusions on the genesis, emplacement and evolution of the Schiel Complex proposed by previous research. , Thesis (MSc) -- Faculty of Science, Geology, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Mahomed, Uzayr
- Date: 2021-10-29
- Subjects: Ultrabasic rocks South Africa Limpopo , Carbonatites South Africa Limpopo , Geology South Africa Limpopo , Mica South Africa Limpopo , Biotite South Africa Limpopo , Magmatism , Schiel Alkaline Complex , Phoscorite , Glimmerite
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/294768 , vital:57253
- Description: Owing to the poor documentation of the phoscorite-carbonatite association present in the Schiel Complex and the associated economic potential of other known phoscorite-bearing complexes, the Schiel Complex is widely thought to have similar economic potential. This complex is often compared to the lucrative Phalaborwa Complex, as it is thought to have crystallised from a common parental melt, with a similar age of emplacement. This study aims to provide clarity on the physical and chemical characterisation of the various rock types present in the Schiel Complex, with this study being the first petrological investigation based on fresh in-situ samples gathered from 3 borehole cores which were drilled by FOSKOR in the 1960s. The sampled sections of the ultramafics from the Schiel Complex are comprised of end-member rock compositions of either magmatic phoscorites or pyroxenites or metasomatic glimmerites, where gradational contacts between these various end-members produce rock varieties that contain characteristics of one or more end-member types. Carbonatite rocks are present as medium-grained, coarse-grained and banded calcio-carbonatite varieties where the carbonatite rocks are proposed as being the metasomatic medium for glimmerite production. Contrary to previous research, the structure of the ultramafic and carbonatite bodies are present as vein and veinlet structures which seem to originate from a single pipe-like body, from which these rock types intruded into the surrounding syenitic country-rock. Metasomatic alteration of the ultramafic sections of the Schiel Complex also show that the carbonatite rocks must have intruded after some ultramafic magmatism. The presence of the same minerals, with similar chemistries, in both the ultramafic and carbonatite rocks as well as similar REE chondrite-normalised plots show that the various rock types may have originated from a common parental magma, where the accumulation and crystallisation of minerals is the most likely factor in producing the various Schiel Complex rock varieties, causing silicate minerals to be present in the carbonate fraction of the magma, and carbonate minerals in the silicate fraction of the magma. Apatite is the expected rare earth element (REE) mineralising mineral in phoscorites, but is shown to be depleted in REE content in the Schiel Complex due to metasomatic fluid infiltration causing the scavenging and dissipation of REEs. These rocks have also crystallised containing no significant copper-bearing mineralisation, contrary to that which is seen in the Phalaborwa Complex. A comparison of mica minerals between the Schiel Complex rocks and the Phalaborwa Complex rocks show that the two complexes have undergone unique emplacement processes and should not be considered as sister complexes. Efforts to date the glimmerite and carbonatite rocks based on zircon grain U/Pb geochronology proved unsuccessful in constraining the current ages of emplacement provided by previous researchers, but rock relationships show that the current accepted sequence of events cannot be correct, providing scope for further research. This study provides an update on the chemical and physical characteristics, based on the only available sample suite of the ultramafic and carbonatite components, of the Schiel Complex, increasing the depth of documentation of these rare rock types and aiding in refuting some conclusions on the genesis, emplacement and evolution of the Schiel Complex proposed by previous research. , Thesis (MSc) -- Faculty of Science, Geology, 2021
- Full Text:
- Date Issued: 2021-10-29
Constraints and enablements on quality improvement in higher education
- Authors: Browning, Leanne Elizabeth
- Date: 2021-10-29
- Subjects: Education, Higher Aims and objectives South Africa , Education, Higher Evaluation , Quality assurance South Africa , Educational evaluation South Africa , Self-evaluation , Critical realism
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294956 , vital:57273 , DOI 10.21504/10962/294956
- Description: This study contributes to the literature on quality improvement in higher education by examining the structural, cultural and agential constraints and enablements on a quality process at a university in South Africa. It examined four cases and developed an understanding of the complex interaction of structure, culture and agency and the mechanisms that enable or constrain quality improvement in higher education. The study drew on the literature on higher education quality for the theoretical basis for what is known contributes to the way in which quality assurance and improvement is implemented and its impact on the higher education context. Critical Realism provided the ontological framework and conceptual tools to understand and explore the complex social world within which the quality process took place. The literature on the morphogenetic approach provided the analytical framework for the data analysis and findings. The data consisted of a set of documents from a quality process that took place over a five-year period. The data analysis revealed that different departmental contexts impact on how mechanisms are activated. Each school context shapes the way in which people engage with the review process and consequently, processes and procedures are mediated in each context. This research therefore adds to the understanding of the way in which quality processes take place at a micro-level within an institutional context and informs the approach to quality improvement more broadly, nationally and internationally. The research contributes to the knowledge that will inform planning, policies and practices in quality improvement processes in higher education and the findings identify a number of factors (mechanisms) that should inform the way in which a quality process is facilitated, will enable effective self-evaluation and review processes, and consequently are more likely to lead to quality improvement. , Thesis (PhD) -- Faculty of Education, Centre for Higher Education Research, Teaching and Learning, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Browning, Leanne Elizabeth
- Date: 2021-10-29
- Subjects: Education, Higher Aims and objectives South Africa , Education, Higher Evaluation , Quality assurance South Africa , Educational evaluation South Africa , Self-evaluation , Critical realism
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294956 , vital:57273 , DOI 10.21504/10962/294956
- Description: This study contributes to the literature on quality improvement in higher education by examining the structural, cultural and agential constraints and enablements on a quality process at a university in South Africa. It examined four cases and developed an understanding of the complex interaction of structure, culture and agency and the mechanisms that enable or constrain quality improvement in higher education. The study drew on the literature on higher education quality for the theoretical basis for what is known contributes to the way in which quality assurance and improvement is implemented and its impact on the higher education context. Critical Realism provided the ontological framework and conceptual tools to understand and explore the complex social world within which the quality process took place. The literature on the morphogenetic approach provided the analytical framework for the data analysis and findings. The data consisted of a set of documents from a quality process that took place over a five-year period. The data analysis revealed that different departmental contexts impact on how mechanisms are activated. Each school context shapes the way in which people engage with the review process and consequently, processes and procedures are mediated in each context. This research therefore adds to the understanding of the way in which quality processes take place at a micro-level within an institutional context and informs the approach to quality improvement more broadly, nationally and internationally. The research contributes to the knowledge that will inform planning, policies and practices in quality improvement processes in higher education and the findings identify a number of factors (mechanisms) that should inform the way in which a quality process is facilitated, will enable effective self-evaluation and review processes, and consequently are more likely to lead to quality improvement. , Thesis (PhD) -- Faculty of Education, Centre for Higher Education Research, Teaching and Learning, 2021
- Full Text:
- Date Issued: 2021-10-29
Culture, gender and forests: social differentiation in coping and adapting to climate change and other stressors in the south west and east regions of Cameroon
- Authors: Enokwena Baa, Ojongetakah
- Date: 2021-10-29
- Subjects: Climatic changes Cameroon , Differentiation (Sociology) Cameroon , Climatic changes Social aspects Cameroon , Cultural awareness Cameroon , Environmental justice Cameroon , Social justice Cameroon , Environmental risk assessment Cameroon , Political ecology Cameroon , Ecofeminism Cameroon , Social capital (Sociology) Cameroon , Community forests Cameroon , Deforestation Cameroon
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/295040 , vital:57284 , DOI 10.21504/10962/295040
- Description: Climate change adaptation scholars and practitioners are beginning to acknowledge that the impact of climate change and other related shocks and stressors will be felt, and reacted to, differently across genders and other types of intersecting social categories, such as age, wealth, and culture, in rural communities. However, to date, most research unpacking these differential impacts and responses has been limited to 'men' versus 'women'. Few studies go beyond this male-female dichotomy to include the different gender structures of households and the intersection with other social factors that contribute to marginalisation, such as ethnicity. This research aimed to explore how different gendered household types in two ethnically diverse communities, the Ejagham and the Baka communities in the SSouth West and East regions of Cameroon, experienced and responded to climate change and other stressors. The central argument of the study is that social differentiation present dynamics and complexities across intersecting identities which determines varied levels of vulnerabilities, adaptive capacity, and livelihood outcomes. The study thus sets out to examine cultural and gendered differentiation in household assets and livelihood activities, how multiple shocks and stressors are experienced, and the differentiated responses to these, focussing specifically on forest and social safety nets. The findings were used to develop an integrated understanding of the complex socially differentiated dimensions of vulnerability and adaptation within the two communities and the implications for more climate secure and equitable livelihoods. The study drew on social-ecological systems, social justice, and feminist political ecology as guiding theoretical lenses. The study further integrated the Moser gender planning and Harvard analytical frameworks as tools for unpacking gender inequality. It followed a mixed methods research design that included household surveys, key informant interviews, and focus group discussions that applied participatory exercises. Financial, human, and physical capital were arguably limited within all household types in both the Ejagham and the Baka communities. Social and natural capital were the most common form of assets that households relied on, with ‘savings groups’ in the Ejagham communities being particularly prevalent. Most households were involved in crop cultivation and forest product collection although there were gendered and cultural differences. Collection of wild fruits, medicinal plants, and condiments, for example, was a more common livelihood activity within the Baka communities and amongst female-headed households. Cultivation of pumpkins and vegetables was dominant amongst households in Ejagham, with these being grown mainly by women, while the cultivation of yams was done by men. Across both communities, female-headed households had less ownership of land compared to male-headed households. The current pressure on agricultural land in the Ejagham communities has decreased crop productivity, with female-headed households disproportionately affected by less ownership of land and thus, options to diversify agricultural activities. Similarly, the rise in individual and private land ownership, in response to resource scarcity and large-scale deforestation in East Cameroon, has further dispossessed female-headed households in the Baka communities, already marginalised by their ethnicity, of land. Inequitable access to assets and the disparity in ownership of these assets across the study communities was both a cause and effect of households' differential livelihood activities and responses to shocks and stressors. Several of the shocks and stressors households were exposed to differed across the two sites. The Ejagham communities, being predominantly agricultural, frequently identified warming temperatures as a climatic stressor and increased sensitivity to the impacts of these. The Baka faced similar climate stressors, although more frequent storms were mentioned as a shock by a significant number of households. The impacts of these storms include damage and destruction of houses due to the traditional construction methods used. Since women are often tasked with the building of houses this adds another layer of stress for them. In terms of idiosyncratic shocks, the death of the main breadwinner was most frequently reported in both communities as a non-climatic shock, although this was higher within the Ejagham communities than in the Baka communities, and particularly so for female-headed households. The varied experiences from multiple shocks and stressors resulted in households' differential coping and adaptation responses. Among the different response options, social and forest safety nets, especially the use and sale of forest products (NTFPs) remained the main response options used by households in both communities. Forest products further supported households during periods of food shortage, especially female-headed households in the Ejagham communities. Households further supported one another through social groups such as savings, farming, hunting (particularly for men) and NTFP collection (for women) groups. By exploring social-ecological interactions, the study highlights the complexities around gender inequalities, vulnerabilities, and responses across socially differentiated groups of people which should be considered in policy, practice, and research. Several of my findings challenge mainstream discourses that generally group women, for instance, as a homogenous category when looking at vulnerability. For example, findings revealed that it is possible for different types of households, both women and men, to be both advantaged and vulnerable at the same time, depending on the shock or stressor faced and the livelihood activities they engage in. The same also applies to ethnicity. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Enokwena Baa, Ojongetakah
- Date: 2021-10-29
- Subjects: Climatic changes Cameroon , Differentiation (Sociology) Cameroon , Climatic changes Social aspects Cameroon , Cultural awareness Cameroon , Environmental justice Cameroon , Social justice Cameroon , Environmental risk assessment Cameroon , Political ecology Cameroon , Ecofeminism Cameroon , Social capital (Sociology) Cameroon , Community forests Cameroon , Deforestation Cameroon
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/295040 , vital:57284 , DOI 10.21504/10962/295040
- Description: Climate change adaptation scholars and practitioners are beginning to acknowledge that the impact of climate change and other related shocks and stressors will be felt, and reacted to, differently across genders and other types of intersecting social categories, such as age, wealth, and culture, in rural communities. However, to date, most research unpacking these differential impacts and responses has been limited to 'men' versus 'women'. Few studies go beyond this male-female dichotomy to include the different gender structures of households and the intersection with other social factors that contribute to marginalisation, such as ethnicity. This research aimed to explore how different gendered household types in two ethnically diverse communities, the Ejagham and the Baka communities in the SSouth West and East regions of Cameroon, experienced and responded to climate change and other stressors. The central argument of the study is that social differentiation present dynamics and complexities across intersecting identities which determines varied levels of vulnerabilities, adaptive capacity, and livelihood outcomes. The study thus sets out to examine cultural and gendered differentiation in household assets and livelihood activities, how multiple shocks and stressors are experienced, and the differentiated responses to these, focussing specifically on forest and social safety nets. The findings were used to develop an integrated understanding of the complex socially differentiated dimensions of vulnerability and adaptation within the two communities and the implications for more climate secure and equitable livelihoods. The study drew on social-ecological systems, social justice, and feminist political ecology as guiding theoretical lenses. The study further integrated the Moser gender planning and Harvard analytical frameworks as tools for unpacking gender inequality. It followed a mixed methods research design that included household surveys, key informant interviews, and focus group discussions that applied participatory exercises. Financial, human, and physical capital were arguably limited within all household types in both the Ejagham and the Baka communities. Social and natural capital were the most common form of assets that households relied on, with ‘savings groups’ in the Ejagham communities being particularly prevalent. Most households were involved in crop cultivation and forest product collection although there were gendered and cultural differences. Collection of wild fruits, medicinal plants, and condiments, for example, was a more common livelihood activity within the Baka communities and amongst female-headed households. Cultivation of pumpkins and vegetables was dominant amongst households in Ejagham, with these being grown mainly by women, while the cultivation of yams was done by men. Across both communities, female-headed households had less ownership of land compared to male-headed households. The current pressure on agricultural land in the Ejagham communities has decreased crop productivity, with female-headed households disproportionately affected by less ownership of land and thus, options to diversify agricultural activities. Similarly, the rise in individual and private land ownership, in response to resource scarcity and large-scale deforestation in East Cameroon, has further dispossessed female-headed households in the Baka communities, already marginalised by their ethnicity, of land. Inequitable access to assets and the disparity in ownership of these assets across the study communities was both a cause and effect of households' differential livelihood activities and responses to shocks and stressors. Several of the shocks and stressors households were exposed to differed across the two sites. The Ejagham communities, being predominantly agricultural, frequently identified warming temperatures as a climatic stressor and increased sensitivity to the impacts of these. The Baka faced similar climate stressors, although more frequent storms were mentioned as a shock by a significant number of households. The impacts of these storms include damage and destruction of houses due to the traditional construction methods used. Since women are often tasked with the building of houses this adds another layer of stress for them. In terms of idiosyncratic shocks, the death of the main breadwinner was most frequently reported in both communities as a non-climatic shock, although this was higher within the Ejagham communities than in the Baka communities, and particularly so for female-headed households. The varied experiences from multiple shocks and stressors resulted in households' differential coping and adaptation responses. Among the different response options, social and forest safety nets, especially the use and sale of forest products (NTFPs) remained the main response options used by households in both communities. Forest products further supported households during periods of food shortage, especially female-headed households in the Ejagham communities. Households further supported one another through social groups such as savings, farming, hunting (particularly for men) and NTFP collection (for women) groups. By exploring social-ecological interactions, the study highlights the complexities around gender inequalities, vulnerabilities, and responses across socially differentiated groups of people which should be considered in policy, practice, and research. Several of my findings challenge mainstream discourses that generally group women, for instance, as a homogenous category when looking at vulnerability. For example, findings revealed that it is possible for different types of households, both women and men, to be both advantaged and vulnerable at the same time, depending on the shock or stressor faced and the livelihood activities they engage in. The same also applies to ethnicity. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2021
- Full Text:
- Date Issued: 2021-10-29