Stump size and the number of coppice shoots for selected savanna tree species
- Authors: Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181896 , vital:43778 , xlink:href="https://doi.org/10.1016/S0254-6299(15)31074-7"
- Description: Management of coppice dynamics of indigenous savanna trees could assist in increasing the regrowth rates or number of coppice shoots produced. This would be useful in natural resource management programmes to promote sustainable resource management. This study examined the influence of cutting height, stem size and surface area on the number of coppice shoots produced for twelve savanna species from a communal land in the Bushbuckndge lowveld. All species exhibited a strong coppicing ability following cutting. The number of shoots per stump was most frequently related to cutting height, although this was not always the most significant predictor. There were clear differences between species with respect to the number of shoots per unit surface area, the highest being for Albizia harveyii and the least Piliostlgma thonningii. The taller the potential height of a species, the fewer were the coppice shoots per stump surface area.
- Full Text:
- Date Issued: 2000
- Authors: Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181896 , vital:43778 , xlink:href="https://doi.org/10.1016/S0254-6299(15)31074-7"
- Description: Management of coppice dynamics of indigenous savanna trees could assist in increasing the regrowth rates or number of coppice shoots produced. This would be useful in natural resource management programmes to promote sustainable resource management. This study examined the influence of cutting height, stem size and surface area on the number of coppice shoots produced for twelve savanna species from a communal land in the Bushbuckndge lowveld. All species exhibited a strong coppicing ability following cutting. The number of shoots per stump was most frequently related to cutting height, although this was not always the most significant predictor. There were clear differences between species with respect to the number of shoots per unit surface area, the highest being for Albizia harveyii and the least Piliostlgma thonningii. The taller the potential height of a species, the fewer were the coppice shoots per stump surface area.
- Full Text:
- Date Issued: 2000
The comparative value of wild and domestic plants in home gardens of a South African rural village
- High, Christopher, Shackleton, Charlie M
- Authors: High, Christopher , Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181907 , vital:43779 , xlink:href="https://doi.org/10.1023/A:1006247614579"
- Description: Rural inhabitants make considerable use of wild resources from communal areas around their settlements, as well as from arable and residential plots. These wild resources compete with the main crops planted in arable plots and home gardens, but play a significant economic and nutritional role in rural livelihoods. This paper reports upon a conservative financial evaluation of the wild plant resources harvested from home gardens and arable plots by inhabitants of rural village in the Bushbuckridge lowveld (South Africa), and examines their importance relative to other domesticated crops. On average, each household made use of four to five species of wild plants growing on their residential plot, whereas the mean number of crop plants was 3.4. The total value of all plants was R1694 (US$ 269) per household per year, or approximately R4200 (US$ 667) per hectare of home garden per year. Wild plants represented 31% of the value of all plants grown on residential plots, relative to the 69% for domesticated crops (including fruit trees). Approximately 72% of the total value of all plant products was consumed by the household, and the remaining 28% was sold.
- Full Text:
- Date Issued: 2000
- Authors: High, Christopher , Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181907 , vital:43779 , xlink:href="https://doi.org/10.1023/A:1006247614579"
- Description: Rural inhabitants make considerable use of wild resources from communal areas around their settlements, as well as from arable and residential plots. These wild resources compete with the main crops planted in arable plots and home gardens, but play a significant economic and nutritional role in rural livelihoods. This paper reports upon a conservative financial evaluation of the wild plant resources harvested from home gardens and arable plots by inhabitants of rural village in the Bushbuckridge lowveld (South Africa), and examines their importance relative to other domesticated crops. On average, each household made use of four to five species of wild plants growing on their residential plot, whereas the mean number of crop plants was 3.4. The total value of all plants was R1694 (US$ 269) per household per year, or approximately R4200 (US$ 667) per hectare of home garden per year. Wild plants represented 31% of the value of all plants grown on residential plots, relative to the 69% for domesticated crops (including fruit trees). Approximately 72% of the total value of all plant products was consumed by the household, and the remaining 28% was sold.
- Full Text:
- Date Issued: 2000
The use of and trade in indigenous edible fruits in the Bushbuckridge savanna region, South Africa
- Shackleton, Charlie M, Dzerefos, Cathy M, Shackleton, Sheona E, Mathabela, F R
- Authors: Shackleton, Charlie M , Dzerefos, Cathy M , Shackleton, Sheona E , Mathabela, F R
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182396 , vital:43826 , xlink:href="https://doi.org/10.1080/03670244.2000.9991616"
- Description: The use, processing, cultivation and trading of indigenous edible fruits was recorded across a rainfall gradient in the Mpumalanga lowveld. Three transects, each consisting of one village in a relatively high rainfall zone, one village in a low rainfall zone, and one intermediate, were sampled by means of 20 households per village. Nearly all households made use of indigenous edible fruits to some extent, with households in the wettest region using the greatest diversity of fruits. The duration of availability of selected species was increased through drying, storing and processing the raw fruits for later consumption. Such activities were more common in the drier regions relative to the wetter villages. Just less than half the respondents maintained indigenous fruit trees within their homestead or arable fields, whereas more than 65% grew exotic commercial fruit species. Many respondents traded in edible fruits, but very few obtained a significant income in this way. Nonetheless, even casual trading provided vital supplementary income for low‐income households.
- Full Text:
- Date Issued: 2000
- Authors: Shackleton, Charlie M , Dzerefos, Cathy M , Shackleton, Sheona E , Mathabela, F R
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182396 , vital:43826 , xlink:href="https://doi.org/10.1080/03670244.2000.9991616"
- Description: The use, processing, cultivation and trading of indigenous edible fruits was recorded across a rainfall gradient in the Mpumalanga lowveld. Three transects, each consisting of one village in a relatively high rainfall zone, one village in a low rainfall zone, and one intermediate, were sampled by means of 20 households per village. Nearly all households made use of indigenous edible fruits to some extent, with households in the wettest region using the greatest diversity of fruits. The duration of availability of selected species was increased through drying, storing and processing the raw fruits for later consumption. Such activities were more common in the drier regions relative to the wetter villages. Just less than half the respondents maintained indigenous fruit trees within their homestead or arable fields, whereas more than 65% grew exotic commercial fruit species. Many respondents traded in edible fruits, but very few obtained a significant income in this way. Nonetheless, even casual trading provided vital supplementary income for low‐income households.
- Full Text:
- Date Issued: 2000
Woodlands in South Africa and the national forests act
- Authors: Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182065 , vital:43796 , xlink:href="https://doi.org/10.1080/10295925.2000.9631252"
- Description: The development of the National Forestry Action Programme (NFAP) and promulgation of the National Forests Act (NFA) have established a new vision for the care, management and distribution of benefits from South Africa's woodlands. The Department of water Affairs and Forestry is mandated with ensuring this vision is put into practice. However, historically the Department has had little to do with woodlands, and suffers from a lack of capacity and expertise, a situation which it readily acknowledges. Additionally, the legal definition of a woodland within the NFA is problematic. Within this context, this paper examines oft cited definitions of woodlands and seeks to find an appropriate one for the South African context. It then briefly reviews the major classifications of woodland types at a national scale, as the minimum basis for homogenous reporting units for which monitoring of the success of the NFAP and the NFA should be pursued. Finally, a brief description of moist/dystrophic and arid/eutrophic woodlands is presented.
- Full Text:
- Date Issued: 2000
- Authors: Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182065 , vital:43796 , xlink:href="https://doi.org/10.1080/10295925.2000.9631252"
- Description: The development of the National Forestry Action Programme (NFAP) and promulgation of the National Forests Act (NFA) have established a new vision for the care, management and distribution of benefits from South Africa's woodlands. The Department of water Affairs and Forestry is mandated with ensuring this vision is put into practice. However, historically the Department has had little to do with woodlands, and suffers from a lack of capacity and expertise, a situation which it readily acknowledges. Additionally, the legal definition of a woodland within the NFA is problematic. Within this context, this paper examines oft cited definitions of woodlands and seeks to find an appropriate one for the South African context. It then briefly reviews the major classifications of woodland types at a national scale, as the minimum basis for homogenous reporting units for which monitoring of the success of the NFAP and the NFA should be pursued. Finally, a brief description of moist/dystrophic and arid/eutrophic woodlands is presented.
- Full Text:
- Date Issued: 2000
δ13C and δ15N biogeographic trends in rocky intertidal communities along the coast of South Africa: evidence of strong environmental signatures
- Hill, Jaclyn M, McQuaid, Christopher D
- Authors: Hill, Jaclyn M , McQuaid, Christopher D
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444664 , vital:74258 , https://doi.org/10.1016/j.ecss.2008.08.005
- Description: Ecosystem dynamics driven by top-down controls have been well documented in rocky intertidal communities, while the effects of bottom-up influences are comparatively poorly understood. We hypothesized that large-scale signatures of the physical environment may be identifiable along the South African coastline as it is subject to two very different current systems (Benguela and Agulhas Currents) that profoundly influence primary production and thus both food type and availability. Through stable isotope analysis, we examined biogeographic patterns in multiple trophic levels at four sites along a 1400-km stretch of South African coastline and investigated the dietary role of macroalgal-derived organic carbon in rocky intertidal communities. The general positioning of trophic groups was comparable across all sites, with animals from the same trophic levels grouping together and with a δ15N fractionation of 1–2‰ between levels.
- Full Text:
- Date Issued: 2000
- Authors: Hill, Jaclyn M , McQuaid, Christopher D
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444664 , vital:74258 , https://doi.org/10.1016/j.ecss.2008.08.005
- Description: Ecosystem dynamics driven by top-down controls have been well documented in rocky intertidal communities, while the effects of bottom-up influences are comparatively poorly understood. We hypothesized that large-scale signatures of the physical environment may be identifiable along the South African coastline as it is subject to two very different current systems (Benguela and Agulhas Currents) that profoundly influence primary production and thus both food type and availability. Through stable isotope analysis, we examined biogeographic patterns in multiple trophic levels at four sites along a 1400-km stretch of South African coastline and investigated the dietary role of macroalgal-derived organic carbon in rocky intertidal communities. The general positioning of trophic groups was comparable across all sites, with animals from the same trophic levels grouping together and with a δ15N fractionation of 1–2‰ between levels.
- Full Text:
- Date Issued: 2000
'Respecting the racist': racism at work
- Authors: Martin, Tom
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454867 , vital:75382 , https://hdl.handle.net/10520/EJC144722
- Description: Racists can believe some pretty odd things, I'm not talking about the completely out-of-left field, lunatic fringe racists who might believe that God deems that white people have dominion over black people, or that there is a Jewish conspiracy to take over the world.
- Full Text: false
- Date Issued: 2001
- Authors: Martin, Tom
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454867 , vital:75382 , https://hdl.handle.net/10520/EJC144722
- Description: Racists can believe some pretty odd things, I'm not talking about the completely out-of-left field, lunatic fringe racists who might believe that God deems that white people have dominion over black people, or that there is a Jewish conspiracy to take over the world.
- Full Text: false
- Date Issued: 2001
A PCA-based modelling technique for predicting environmental suitability for organisms from presence records
- Robertson, Mark P, Caithness, N, Villet, Martin H
- Authors: Robertson, Mark P , Caithness, N , Villet, Martin H
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442609 , vital:74014 , https://doi.org/10.1046/j.1472-4642.2001.00094.x
- Description: We present a correlative modelling technique that uses locality records (associated with species presence) and a set of predictor variables to produce a statistically justifiable probability response surface for a target species. The probability response surface indicates the suitability of each grid cell in a map for the target species in terms of the suite of predictor variables. The technique constructs a hyperspace for the target species using principal component axes derived from a principal components analysis performed on a training dataset. The training dataset comprises the values of the predictor variables associated with the localities where the species has been recorded as present. The origin of this hyperspace is taken to characterize the centre of the niche of the organism. All the localities (grid‐cells) in the map region are then fitted into this hyperspace using the values of the predictor variables at these localities (the prediction dataset). The Euclidean distance from any locality to the origin of the hyperspace gives a measure of the ‘centrality’ of that locality in the hyperspace. These distances are used to derive probability values for each grid cell in the map region. The modelling technique was applied to bioclimatic data to predict bioclimatic suitability for three alien invasive plant species (Lantana camara L., Ricinus communis L. and Solanum mauritianum Scop.) in South Africa, Lesotho and Swaziland. The models were tested against independent test records by calculating area under the curve (AUC) values of receiver operator characteristic (ROC) curves and kappa statistics. There was good agreement between the models and the independent test records. The pre‐processing of climatic variable data to reduce the deleterious effects of multicollinearity, and the use of stopping rules to prevent overfitting of the models are important aspects of the modelling process.
- Full Text:
- Date Issued: 2001
- Authors: Robertson, Mark P , Caithness, N , Villet, Martin H
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442609 , vital:74014 , https://doi.org/10.1046/j.1472-4642.2001.00094.x
- Description: We present a correlative modelling technique that uses locality records (associated with species presence) and a set of predictor variables to produce a statistically justifiable probability response surface for a target species. The probability response surface indicates the suitability of each grid cell in a map for the target species in terms of the suite of predictor variables. The technique constructs a hyperspace for the target species using principal component axes derived from a principal components analysis performed on a training dataset. The training dataset comprises the values of the predictor variables associated with the localities where the species has been recorded as present. The origin of this hyperspace is taken to characterize the centre of the niche of the organism. All the localities (grid‐cells) in the map region are then fitted into this hyperspace using the values of the predictor variables at these localities (the prediction dataset). The Euclidean distance from any locality to the origin of the hyperspace gives a measure of the ‘centrality’ of that locality in the hyperspace. These distances are used to derive probability values for each grid cell in the map region. The modelling technique was applied to bioclimatic data to predict bioclimatic suitability for three alien invasive plant species (Lantana camara L., Ricinus communis L. and Solanum mauritianum Scop.) in South Africa, Lesotho and Swaziland. The models were tested against independent test records by calculating area under the curve (AUC) values of receiver operator characteristic (ROC) curves and kappa statistics. There was good agreement between the models and the independent test records. The pre‐processing of climatic variable data to reduce the deleterious effects of multicollinearity, and the use of stopping rules to prevent overfitting of the models are important aspects of the modelling process.
- Full Text:
- Date Issued: 2001
A sensitive and reliable method for the detection of lipid peroxidation in biological tissues
- Anoopkumar-Dukie, Shailendra, Walker, Roderick B, Daya, Santylal
- Authors: Anoopkumar-Dukie, Shailendra , Walker, Roderick B , Daya, Santylal
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184325 , vital:44208 , xlink:href="https://doi.org/10.1211/0022357011775299"
- Description: A simple, accurate and cost effective method has been designed for the determination of lipid peroxidation in biological tissue samples. The method was a modification and improvement on existing methods available for lipid peroxidation determination. Solid-phase extraction was used to separate the thiobarbituric acid–malondialdehyde complex from thiobarbituric acidreactive substances and HPLC was performed using a C18 (Waters Spherisorb, 5 µm, 250¬4.6 mm i.d.) column to achieve isolation of the complex. The procedure was validated with respect to linearity of calibration (0.998), precision, sensitivity and limits of quantitation (1 nmol mL−1) and detection (0.5 nmol mL−1). Resorcinol was used as an external standard. The method was tested by inducing free radical generation with a known free radical generator, quinolinic acid, in rat brain homogenate. The results showed that the method presented allowed detection of lipid peroxidation products at concentrations in the nanomolar (nM) range compared with the micromolar (µM) range detected by other methods, thus rendering it suitable for use with biological samples. In addition, the modified method allowed for detection of the purified lipid peroxidation products, thus eliminating the possibility of simultaneous detection of impurities that absorb at the same wavelength.
- Full Text:
- Date Issued: 2001
- Authors: Anoopkumar-Dukie, Shailendra , Walker, Roderick B , Daya, Santylal
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184325 , vital:44208 , xlink:href="https://doi.org/10.1211/0022357011775299"
- Description: A simple, accurate and cost effective method has been designed for the determination of lipid peroxidation in biological tissue samples. The method was a modification and improvement on existing methods available for lipid peroxidation determination. Solid-phase extraction was used to separate the thiobarbituric acid–malondialdehyde complex from thiobarbituric acidreactive substances and HPLC was performed using a C18 (Waters Spherisorb, 5 µm, 250¬4.6 mm i.d.) column to achieve isolation of the complex. The procedure was validated with respect to linearity of calibration (0.998), precision, sensitivity and limits of quantitation (1 nmol mL−1) and detection (0.5 nmol mL−1). Resorcinol was used as an external standard. The method was tested by inducing free radical generation with a known free radical generator, quinolinic acid, in rat brain homogenate. The results showed that the method presented allowed detection of lipid peroxidation products at concentrations in the nanomolar (nM) range compared with the micromolar (µM) range detected by other methods, thus rendering it suitable for use with biological samples. In addition, the modified method allowed for detection of the purified lipid peroxidation products, thus eliminating the possibility of simultaneous detection of impurities that absorb at the same wavelength.
- Full Text:
- Date Issued: 2001
Active learning in schools
- Lotz-Sisitka, Heila, Timmermans, Ingrid
- Authors: Lotz-Sisitka, Heila , Timmermans, Ingrid
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/389696 , vital:68475 , xlink:href="https://eeasa.org.za/wp-content/uploads/2016/12/Bulletin_vol21-_Sep-2001.pdf"
- Description: The Rhodes University Environmental Education Unit has initiated a project to support school-based environmental education work in Grahamstown. In line with national environmental education policy, the project supports a focus on environmental learning in the context of the OBE curriculum, and provides professional development support to teachers implementing the project (NEEP, 2000). An action research evaluation is taking place to monitor key aspects of the project and a number of interim evaluation reports have been produced (Mbanjwa, 2001).
- Full Text:
- Date Issued: 2001
- Authors: Lotz-Sisitka, Heila , Timmermans, Ingrid
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/389696 , vital:68475 , xlink:href="https://eeasa.org.za/wp-content/uploads/2016/12/Bulletin_vol21-_Sep-2001.pdf"
- Description: The Rhodes University Environmental Education Unit has initiated a project to support school-based environmental education work in Grahamstown. In line with national environmental education policy, the project supports a focus on environmental learning in the context of the OBE curriculum, and provides professional development support to teachers implementing the project (NEEP, 2000). An action research evaluation is taking place to monitor key aspects of the project and a number of interim evaluation reports have been produced (Mbanjwa, 2001).
- Full Text:
- Date Issued: 2001
An inventory of medicinal plants traded on the western boundary of the Kruger National Park, South Africa
- Botha, Jenny, Witkowski, Ed T F, Shackleton, Charlie M
- Authors: Botha, Jenny , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181662 , vital:43756 , xlink:href="https://doi.org/10.4102/koedoe.v44i2.172"
- Description: The World Health Organisation estimates that traditional medicine still plays a vital role in the lives of 70-80 of the populations of developing countries. Approximately 20 000 tons of medicinal plants are estimated to be traded in South Africa annually, resulting in considerable pressure on the wild populations from which these plants are harvested. In 1997, a study was initiated to assess the extent of trade in medicinal plants on the western boundary of the Kruger National Park, and to determine local perceptions of the availability and values of these plants. This paper presents an inventory of the species traded, including vendors' and traders' perceptions of current availability of species and consumer demand, as well as price/kg. In Mpumalanga, 176 species were identified (71 of the vernacular names encountered in the market place), representing 69 families. In Northern Province, 70 different species were identified (84 of the vernacular names recorded in the markets), representing 40 families. Perceptions of availability of a species varied considerably, often within the same markets. Perceptions of demand tended to be more consistent, although these also sometimes varied. Although monitoring markets is an efficient means of assessing the conservation status of medicinal plants, it is important to select appropriate parameters. Markets often differ from one another, and an understanding of local conditions is crucial. For example, in the medicinal markets on the western boundary of the Kruger National Park, price/kg and market perceptions of availability of species were highly variable and would thus not provide a consistent monitoring parameter. Perceptions of demand provide an indication of current and potential pressure on a species, particularly when combined with the monitoring of species traded, and the introduction of substitutes in the market place. The size of plant parts traded could also provide useful monitoring data. It is important to identify the plants utilised locally first hand where possible, due to the variation of vernacular names from one area to another.
- Full Text:
- Date Issued: 2001
- Authors: Botha, Jenny , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181662 , vital:43756 , xlink:href="https://doi.org/10.4102/koedoe.v44i2.172"
- Description: The World Health Organisation estimates that traditional medicine still plays a vital role in the lives of 70-80 of the populations of developing countries. Approximately 20 000 tons of medicinal plants are estimated to be traded in South Africa annually, resulting in considerable pressure on the wild populations from which these plants are harvested. In 1997, a study was initiated to assess the extent of trade in medicinal plants on the western boundary of the Kruger National Park, and to determine local perceptions of the availability and values of these plants. This paper presents an inventory of the species traded, including vendors' and traders' perceptions of current availability of species and consumer demand, as well as price/kg. In Mpumalanga, 176 species were identified (71 of the vernacular names encountered in the market place), representing 69 families. In Northern Province, 70 different species were identified (84 of the vernacular names recorded in the markets), representing 40 families. Perceptions of availability of a species varied considerably, often within the same markets. Perceptions of demand tended to be more consistent, although these also sometimes varied. Although monitoring markets is an efficient means of assessing the conservation status of medicinal plants, it is important to select appropriate parameters. Markets often differ from one another, and an understanding of local conditions is crucial. For example, in the medicinal markets on the western boundary of the Kruger National Park, price/kg and market perceptions of availability of species were highly variable and would thus not provide a consistent monitoring parameter. Perceptions of demand provide an indication of current and potential pressure on a species, particularly when combined with the monitoring of species traded, and the introduction of substitutes in the market place. The size of plant parts traded could also provide useful monitoring data. It is important to identify the plants utilised locally first hand where possible, due to the variation of vernacular names from one area to another.
- Full Text:
- Date Issued: 2001
Ariel in Africa: Leslie French and the Port Elizabeth Shakespearean Festival
- Mann, Bruce, Wright, Laurence
- Authors: Mann, Bruce , Wright, Laurence
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/455588 , vital:75441 , https://hdl.handle.net/10520/AJA1011582X_168
- Description: The Port Elizabeth Shakespearean Festival has good reason to remember the 23'd April. Quite apart from its being the official birthday of Shakespeare and St. George (after whom the park was named in which Mannville, the company's open air theatre, stands today), the 23'd April 1904 was the birthday of Leslie French, doyen of classical theatre in South Africa in the last century, whose productions established and consolidated open-air theatre in Port Elizabeth. He had a varied and successful career in the performing arts well before his association with South African theatre began. A gifted boy singer, his first appearance was in London at the Little Theatre, December 141", 1914, while he was still a chorister at the London College of Choristers. In the next four years he appeared regularly with Jean Sterling Machinlay and Harcourt Williams at the Margaret Morris Theatre, as a soloist at many important London churches (including St. Margaret's, Westminster Abbey and St. Paul's Cathedral), as well as singing at the Royal Albert Hall and the Queen's Hall in the Chapel Ballad Concerts.
- Full Text:
- Date Issued: 2001
- Authors: Mann, Bruce , Wright, Laurence
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/455588 , vital:75441 , https://hdl.handle.net/10520/AJA1011582X_168
- Description: The Port Elizabeth Shakespearean Festival has good reason to remember the 23'd April. Quite apart from its being the official birthday of Shakespeare and St. George (after whom the park was named in which Mannville, the company's open air theatre, stands today), the 23'd April 1904 was the birthday of Leslie French, doyen of classical theatre in South Africa in the last century, whose productions established and consolidated open-air theatre in Port Elizabeth. He had a varied and successful career in the performing arts well before his association with South African theatre began. A gifted boy singer, his first appearance was in London at the Little Theatre, December 141", 1914, while he was still a chorister at the London College of Choristers. In the next four years he appeared regularly with Jean Sterling Machinlay and Harcourt Williams at the Margaret Morris Theatre, as a soloist at many important London churches (including St. Margaret's, Westminster Abbey and St. Paul's Cathedral), as well as singing at the Royal Albert Hall and the Queen's Hall in the Chapel Ballad Concerts.
- Full Text:
- Date Issued: 2001
Changes in the abundance of cells in the anterior pituitary gland and the possible roles of luteinizing hormone, prolactin and progesterone in the control of delayed implantation in the straw-coloured fruit bat (Eidolon helvum)
- Simbauni, J A, Bernard, Ric T F
- Authors: Simbauni, J A , Bernard, Ric T F
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447131 , vital:74586 , https://doi.org/10.1080/15627020.2001.11657115
- Description: Eidolon helvum (Megachiroptera) is a large frugivorous bat found in equatorial and tropical Africa. The reproductive cycle is characterized by a three-month period of delayed implantation and the total length of pregnancy may be as much as 10 months. A histochemical study of the gonadotrophs and mammotrophs of the anterior pituitary, in conjunction with assays of LH-like, progesterone-like and prolactin-like immunoreactivity in the plasma suggest that during delayed implantation the gonadotrophs were inactive while the mammotrophs were active and plasma PRL-like immunoreactivity high. We interpret this as indicating that, in the straw-coloured fruit bat, implantation was inhibited by high levels of prolactin and, as such, the endocrine control of delayed implantation may be quite different from that described for other mammals.
- Full Text:
- Date Issued: 2001
- Authors: Simbauni, J A , Bernard, Ric T F
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447131 , vital:74586 , https://doi.org/10.1080/15627020.2001.11657115
- Description: Eidolon helvum (Megachiroptera) is a large frugivorous bat found in equatorial and tropical Africa. The reproductive cycle is characterized by a three-month period of delayed implantation and the total length of pregnancy may be as much as 10 months. A histochemical study of the gonadotrophs and mammotrophs of the anterior pituitary, in conjunction with assays of LH-like, progesterone-like and prolactin-like immunoreactivity in the plasma suggest that during delayed implantation the gonadotrophs were inactive while the mammotrophs were active and plasma PRL-like immunoreactivity high. We interpret this as indicating that, in the straw-coloured fruit bat, implantation was inhibited by high levels of prolactin and, as such, the endocrine control of delayed implantation may be quite different from that described for other mammals.
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- Date Issued: 2001
Comparative photosensitised transformation of polychlorophenols with different sulphonated metallophthalocyanine complexes in aqueous medium
- Ozoemena, Kenneth, Kuznetsova, Nina, Nyokong, Tebello
- Authors: Ozoemena, Kenneth , Kuznetsova, Nina , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291520 , vital:56883 , xlink:href="https://doi.org/10.1016/S1381-1169(01)00243-6"
- Description: The relative efficiencies for the oxidation of trichlorophenol (TCP) and pentachlorophenol (PCP), sensitised by sulphonated phthalocyanine complexes containing Zn, Al, Sn and Si as central metals, were studied in aqueous solutions. For the first time, sulphonated silicon and tin phthalocyanines were synthesised and their activity towards photosensitisation of singlet oxygen and photo-oxidation of polychlorophenols was examined. The efficiency of the sensitised photo-oxidative degradation of polychlorophenols depends not only on singlet oxygen quantum yield of sensitiser, but also on its stability. The influence of substrate structure and the pH of the solution on the photo-oxidation efficiency, as well as on the sensitiser photodegradation were studied. It was found that the contribution of the Type II (singlet oxygen-mediated) mechanism to the relative efficiency of the photosensitised photo-oxidation of the phenol, decreased from phenol to p-chlorophenol, TCP and PCP, whereas Type I radical pathway increased. The results obtained for PCP give evidence that electron transfer from the excited sensitiser to the substrate in its unionised form is responsible for enhanced sensitiser photodegradation.
- Full Text:
- Date Issued: 2001
- Authors: Ozoemena, Kenneth , Kuznetsova, Nina , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291520 , vital:56883 , xlink:href="https://doi.org/10.1016/S1381-1169(01)00243-6"
- Description: The relative efficiencies for the oxidation of trichlorophenol (TCP) and pentachlorophenol (PCP), sensitised by sulphonated phthalocyanine complexes containing Zn, Al, Sn and Si as central metals, were studied in aqueous solutions. For the first time, sulphonated silicon and tin phthalocyanines were synthesised and their activity towards photosensitisation of singlet oxygen and photo-oxidation of polychlorophenols was examined. The efficiency of the sensitised photo-oxidative degradation of polychlorophenols depends not only on singlet oxygen quantum yield of sensitiser, but also on its stability. The influence of substrate structure and the pH of the solution on the photo-oxidation efficiency, as well as on the sensitiser photodegradation were studied. It was found that the contribution of the Type II (singlet oxygen-mediated) mechanism to the relative efficiency of the photosensitised photo-oxidation of the phenol, decreased from phenol to p-chlorophenol, TCP and PCP, whereas Type I radical pathway increased. The results obtained for PCP give evidence that electron transfer from the excited sensitiser to the substrate in its unionised form is responsible for enhanced sensitiser photodegradation.
- Full Text:
- Date Issued: 2001
Construction and characterization of carbon paste ultra-microelectrodes
- Oni, Joshua, Westbroek, Philippe, Nyokong, Tebello
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291531 , vital:56884 , xlink:href="https://doi.org/10.1016/S1388-2481(01)00212-0"
- Description: The construction and characterization of carbon paste ultra-microelectrodes is reported. Besides a disc-shaped electrode, a carbon paste band electrode is studied. It was found that for both electrode configurations steady-state currents were obtained but that with the type of electrode material used for the band electrode, the upper limit of ultra-microelectrode dimensions, which could be used was 100–150 μm. Smaller dimensions for the band electrodes resulted in a high resistance due to the limited conductivity of the carbon paste, when using the optimal paste composition. With cyclic voltammetry, the oxidation of [Fe(CN)6]4− was studied at individual constructed electrodes and at ensembles of individual electrodes. Detection limits of less than 10−6moll−1 were obtained. Using the data of the same curves it was possible to test if the electrodes have errors and about 20% of the constructed electrodes did not pass this test. Finally it was found that these electrodes show good stability.
- Full Text:
- Date Issued: 2001
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291531 , vital:56884 , xlink:href="https://doi.org/10.1016/S1388-2481(01)00212-0"
- Description: The construction and characterization of carbon paste ultra-microelectrodes is reported. Besides a disc-shaped electrode, a carbon paste band electrode is studied. It was found that for both electrode configurations steady-state currents were obtained but that with the type of electrode material used for the band electrode, the upper limit of ultra-microelectrode dimensions, which could be used was 100–150 μm. Smaller dimensions for the band electrodes resulted in a high resistance due to the limited conductivity of the carbon paste, when using the optimal paste composition. With cyclic voltammetry, the oxidation of [Fe(CN)6]4− was studied at individual constructed electrodes and at ensembles of individual electrodes. Detection limits of less than 10−6moll−1 were obtained. Using the data of the same curves it was possible to test if the electrodes have errors and about 20% of the constructed electrodes did not pass this test. Finally it was found that these electrodes show good stability.
- Full Text:
- Date Issued: 2001
Effect of oligomerization on the photochemical properties of silicon octaphenoxyphthalocyanine
- Maree, M David, Nyokong, Tebello
- Authors: Maree, M David , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291542 , vital:56885 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00485-3"
- Description: The photochemical properties of silicon octaphenoxyphthalocyanines (SiOPPc) oligomerized were studied in dimethylsulfoxide (DMSO) solutions. Oligomers containing 2–5 and 9 SiOPPc rings linked with terephthalate linkages were synthesized. Singlet oxygen quantum yields were found to be in the range 0.11–0.34, and increased with the number of rings up to five rings, a decrease in the quantum yield was observed for nine rings. This is explained in terms of the high aggregation of the oligomer containing nine rings.
- Full Text:
- Date Issued: 2001
- Authors: Maree, M David , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291542 , vital:56885 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00485-3"
- Description: The photochemical properties of silicon octaphenoxyphthalocyanines (SiOPPc) oligomerized were studied in dimethylsulfoxide (DMSO) solutions. Oligomers containing 2–5 and 9 SiOPPc rings linked with terephthalate linkages were synthesized. Singlet oxygen quantum yields were found to be in the range 0.11–0.34, and increased with the number of rings up to five rings, a decrease in the quantum yield was observed for nine rings. This is explained in terms of the high aggregation of the oligomer containing nine rings.
- Full Text:
- Date Issued: 2001
Electrooxidation of cresols on carbon electrodes modified with phthalocyaninato and octabutoxyphthalocyaninato cobalt (II) complexes
- Grootboom, Natasha, Nyokong, Tebello
- Authors: Grootboom, Natasha , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293207 , vital:57065 , xlink:href="https://doi.org/10.1016/S0003-2670(00)01351-9"
- Description: Glassy carbon electrodes (GCE) modified with cobalt(II) phthalocyanine (CoPc-GCE) and cobalt(II) octabutoxyphthalocyanine (CoOBuPc-GCE) were employed for the electrochemical analysis of ortho-, meta-, and para-cresols. The oxidation potential of p-cresol was shifted towards less positive values to a larger extent, when compared to m- and o-cresols, on CoOBuPc-GCE. However, the GCE was less stable when modified with CoOBuPc than with CoPc. This is explained using the possible differences in the orientation of the adsorbed phthalocyanine molecules on the electrode. Bulk electrolysis of p-cresol at anodic potentials (1.0 V versus Ag|AgCl) on carbon electrodes modified with CoPc resulted in the formation of radicals which coupled to form trimeric products. On unmodified carbon electrodes, coupling of the radicals resulted in dimeric products following bulk electrolysis. The products formed following bulk electrolysis were characterized by liquid chromatography coupled with mass spectrometry.
- Full Text:
- Date Issued: 2001
- Authors: Grootboom, Natasha , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293207 , vital:57065 , xlink:href="https://doi.org/10.1016/S0003-2670(00)01351-9"
- Description: Glassy carbon electrodes (GCE) modified with cobalt(II) phthalocyanine (CoPc-GCE) and cobalt(II) octabutoxyphthalocyanine (CoOBuPc-GCE) were employed for the electrochemical analysis of ortho-, meta-, and para-cresols. The oxidation potential of p-cresol was shifted towards less positive values to a larger extent, when compared to m- and o-cresols, on CoOBuPc-GCE. However, the GCE was less stable when modified with CoOBuPc than with CoPc. This is explained using the possible differences in the orientation of the adsorbed phthalocyanine molecules on the electrode. Bulk electrolysis of p-cresol at anodic potentials (1.0 V versus Ag|AgCl) on carbon electrodes modified with CoPc resulted in the formation of radicals which coupled to form trimeric products. On unmodified carbon electrodes, coupling of the radicals resulted in dimeric products following bulk electrolysis. The products formed following bulk electrolysis were characterized by liquid chromatography coupled with mass spectrometry.
- Full Text:
- Date Issued: 2001
Experiences in porting a virtual reality system to Java
- Authors: Bangay, Shaun D
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433157 , vital:72947 , https://doi.org/10.1145/513867.513875
- Description: Practical experience in porting a large virtual reality system from C/C++ to Java indicates that porting this type of real-time application is both feasible, and has several merits. The ability to transfer objects in space and time allows useful facilities such as distributed agent support and persistence to be added. Reflection and type comparisons allow flexible manipulations of objects of different types at run-time. Native calls and native code compilation reduce or remove the overhead of interpreting code.Problems encountered include difficulty in achieving cross-platform code portability, limitations of the networking libraries in Java, and clumsy coding practices forced by the language.
- Full Text:
- Date Issued: 2001
- Authors: Bangay, Shaun D
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433157 , vital:72947 , https://doi.org/10.1145/513867.513875
- Description: Practical experience in porting a large virtual reality system from C/C++ to Java indicates that porting this type of real-time application is both feasible, and has several merits. The ability to transfer objects in space and time allows useful facilities such as distributed agent support and persistence to be added. Reflection and type comparisons allow flexible manipulations of objects of different types at run-time. Native calls and native code compilation reduce or remove the overhead of interpreting code.Problems encountered include difficulty in achieving cross-platform code portability, limitations of the networking libraries in Java, and clumsy coding practices forced by the language.
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- Date Issued: 2001
Factors Influencing the Entrepreneurial Orientation of Students
- Amos, Trevor L, Louw, L, Baxter, Jeremy
- Authors: Amos, Trevor L , Louw, L , Baxter, Jeremy
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270879 , vital:54488 , xlink:href="https://scialert.net/abstract/?doi=jas.2001.329.334"
- Description: With entrepreneurship being an important catalyst in wealth creation, it is imperative that entrepreneurs be developed. The aim of this exploratory research is to contribute to our understanding of the development of entrepreneurs and to encourage further research in the area. This paper proposes a model of entrepreneurship and tests the influencing factors on this model. Based on the findings of this research, it appears that entrepreneurial activity of family members influences the development of entrepreneurship more than gender, race, age or education. With education being a logical site for the development of entrepreneurship within society, this finding raises more questions than it provides answers, highlighting the need for educators to critically review the educational process if entrepreneurship is to be a realistic outcome.
- Full Text:
- Date Issued: 2001
- Authors: Amos, Trevor L , Louw, L , Baxter, Jeremy
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270879 , vital:54488 , xlink:href="https://scialert.net/abstract/?doi=jas.2001.329.334"
- Description: With entrepreneurship being an important catalyst in wealth creation, it is imperative that entrepreneurs be developed. The aim of this exploratory research is to contribute to our understanding of the development of entrepreneurs and to encourage further research in the area. This paper proposes a model of entrepreneurship and tests the influencing factors on this model. Based on the findings of this research, it appears that entrepreneurial activity of family members influences the development of entrepreneurship more than gender, race, age or education. With education being a logical site for the development of entrepreneurship within society, this finding raises more questions than it provides answers, highlighting the need for educators to critically review the educational process if entrepreneurship is to be a realistic outcome.
- Full Text:
- Date Issued: 2001
Implementation and applications of the distortion operator
- Authors: Bangay, Shaun D
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433382 , vital:72966 , https://doi.org/10.1145/513867.513872
- Description: The distortion operator transforms 2D images in a manner similar to image warping or morphing, allowing source pixels to be mapped to any destination pixel. This operator can be implemented on current hardware, allowing at least one distortion per frame at interactive frame rates. Potential applications are numerous, but those described include re-mapping images for correct projection onto curved screens, correcting camera distortion from multiple sources simultaneously, and allowing constant time dynamic texturing and lighting of a static scene which is independent of geometric complexity.
- Full Text:
- Date Issued: 2001
- Authors: Bangay, Shaun D
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433382 , vital:72966 , https://doi.org/10.1145/513867.513872
- Description: The distortion operator transforms 2D images in a manner similar to image warping or morphing, allowing source pixels to be mapped to any destination pixel. This operator can be implemented on current hardware, allowing at least one distortion per frame at interactive frame rates. Potential applications are numerous, but those described include re-mapping images for correct projection onto curved screens, correcting camera distortion from multiple sources simultaneously, and allowing constant time dynamic texturing and lighting of a static scene which is independent of geometric complexity.
- Full Text:
- Date Issued: 2001
Influences of food quality and quantity on the male reproductive organs of a seasonally breeding rodent, the pouched mouse (Saccostomus campestris), from a seasonal but unpredictable environment
- Tinney, Gregory M, Bernard, Ric T F, White, Rehema M
- Authors: Tinney, Gregory M , Bernard, Ric T F , White, Rehema M
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447258 , vital:74600 , https://doi.org/10.1080/15627020.2001.11657110
- Description: Reproduction in the pouched mouse (Saccostomus campestris) is inhibited in winter in the field and this seasonality is not controlled by photoperiod alone. The present study examines the hypothesis that reproduction in the pouched mouse is opportunistic (sensu Bronson 1989) and that the winter inhibition of reproduction is controlled by a reduction in either food quantity or quality. Food restriction (70 % of normal daily food intake) for six weeks, under short day conditions, was associated with a significant decrease in body fat index and mass of the accessory glands, testes and epididymides, while a high-fibre diet resulted in a significant reduction in fat index and masses of both the accessory glands and epididymides. A low-fibre/low-protein diet had no significant effect on either fat index or masses of the reproductive organs. Although the three experimental diets resulted in assimilation of significantly less energy than the controls, they did not inhibit spermatogenesis. We conclude that reproduction in the pouched mouse in the Eastern Cape Province is probably opportunistic and that the winter inhibition of reproduction may be controlled by a reduction in available energy which results from a combination of the lower ambient temperatures of winter and reduced food quantity and/or quality.
- Full Text:
- Date Issued: 2001
- Authors: Tinney, Gregory M , Bernard, Ric T F , White, Rehema M
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447258 , vital:74600 , https://doi.org/10.1080/15627020.2001.11657110
- Description: Reproduction in the pouched mouse (Saccostomus campestris) is inhibited in winter in the field and this seasonality is not controlled by photoperiod alone. The present study examines the hypothesis that reproduction in the pouched mouse is opportunistic (sensu Bronson 1989) and that the winter inhibition of reproduction is controlled by a reduction in either food quantity or quality. Food restriction (70 % of normal daily food intake) for six weeks, under short day conditions, was associated with a significant decrease in body fat index and mass of the accessory glands, testes and epididymides, while a high-fibre diet resulted in a significant reduction in fat index and masses of both the accessory glands and epididymides. A low-fibre/low-protein diet had no significant effect on either fat index or masses of the reproductive organs. Although the three experimental diets resulted in assimilation of significantly less energy than the controls, they did not inhibit spermatogenesis. We conclude that reproduction in the pouched mouse in the Eastern Cape Province is probably opportunistic and that the winter inhibition of reproduction may be controlled by a reduction in available energy which results from a combination of the lower ambient temperatures of winter and reduced food quantity and/or quality.
- Full Text:
- Date Issued: 2001