Does national sporting performance affect stock market returns in South Africa?
- Authors: Botha, Ferdi , De Beer, Carl
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396023 , vital:69144 , xlink:href="https://hdl.handle.net/10520/EJC135922"
- Description: This study explores whether South African national sporting performance can influence investors in such a way that it has the ability to impact on market returns. Using standard event study methodology, this study determines the constant mean return using the daily All-Share price index on the JSE for the period of 1 January 1990 to 31 December 2010. This study focuses on three of South Africa's most popular sports, namely soccer, cricket and rugby, and examines if these three sports have the ability to influence market returns. Although there is some evidence of a relationship between stock returns and sporting performance in the descriptive analysis, the regression results indicate that sporting performance in South Africa does not significantly explain abnormal market returns on the JSE. The study provides a number of possible reasons for this finding and concludes by suggesting areas for future research.
- Full Text:
- Authors: Botha, Ferdi , De Beer, Carl
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396023 , vital:69144 , xlink:href="https://hdl.handle.net/10520/EJC135922"
- Description: This study explores whether South African national sporting performance can influence investors in such a way that it has the ability to impact on market returns. Using standard event study methodology, this study determines the constant mean return using the daily All-Share price index on the JSE for the period of 1 January 1990 to 31 December 2010. This study focuses on three of South Africa's most popular sports, namely soccer, cricket and rugby, and examines if these three sports have the ability to influence market returns. Although there is some evidence of a relationship between stock returns and sporting performance in the descriptive analysis, the regression results indicate that sporting performance in South Africa does not significantly explain abnormal market returns on the JSE. The study provides a number of possible reasons for this finding and concludes by suggesting areas for future research.
- Full Text:
Dog wars : a Victorian steampunk adventure
- Authors: Molino, Nicolene Chloe
- Date: 2013
- Subjects: Creative writing , Fiction , South Africa , Creative writing (Higher education) , Short stories, South African (English) -- 21st century , South African fiction (English) -- 21st century , English language -- Writing
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:5965 , http://hdl.handle.net/10962/d1001815
- Description: We're in an alternate universe, circa Dickensian London. Leofric Lieven, a local crime lord, is about to find the past catching up on him. The Romany Carnival has come to town, and a gypsy woman, his former lover and partner in crime, demands from him a favour which will redress his betrayal of years before: he must secure a stolen object and return it to her. But things go horribly wrong when local delivery boy Cards Bennish is kidnapped by Leofric’s competitor before he can deliver the goods that will cover Leofric's debt to the gypsy. In this world, humans can shape shift into animals, entirely or only partially, dog fighting is the favourite pastime for high stakes betting, and power belongs to the highest bidder. The gypsy’s final bet, for the highest stakes yet, will seal the fates of a number of people, for better or worse
- Full Text:
- Authors: Molino, Nicolene Chloe
- Date: 2013
- Subjects: Creative writing , Fiction , South Africa , Creative writing (Higher education) , Short stories, South African (English) -- 21st century , South African fiction (English) -- 21st century , English language -- Writing
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:5965 , http://hdl.handle.net/10962/d1001815
- Description: We're in an alternate universe, circa Dickensian London. Leofric Lieven, a local crime lord, is about to find the past catching up on him. The Romany Carnival has come to town, and a gypsy woman, his former lover and partner in crime, demands from him a favour which will redress his betrayal of years before: he must secure a stolen object and return it to her. But things go horribly wrong when local delivery boy Cards Bennish is kidnapped by Leofric’s competitor before he can deliver the goods that will cover Leofric's debt to the gypsy. In this world, humans can shape shift into animals, entirely or only partially, dog fighting is the favourite pastime for high stakes betting, and power belongs to the highest bidder. The gypsy’s final bet, for the highest stakes yet, will seal the fates of a number of people, for better or worse
- Full Text:
Drivers of macrophyte assemblages in South African freshwater systems
- Authors: Martin, Grant Douglas
- Date: 2013
- Subjects: Freshwater plants -- South Africa Aquatic weeds -- South Africa Invasive plants -- South Africa Freshwater ecology -- South Africa Biotic communities -- South Africa Maximum entropy method Lagarosiphon major -- South Africa Phytophagous insects -- South Africa Hydrellia -- South Africa Parasitoids -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5621 , http://hdl.handle.net/10962/d1004127
- Description: Potentially damaging submerged invasive freshwater macrophytes have been identified in South African freshwater systems, but have received less attention than their floating counterparts. To ascertain the changes and effects that these species may have on macrophyte ecology, an understanding of the drivers of macrophyte assemblages is essential. The aims of this thesis were to investigate select abiotic and biotic factors driving introduction, establishment and spread of submerged macrophytes in South Africa. Surveys on the status of submerged plant species in South Africa were conducted to find out the distribution and diversity of the species present, imported to, and traded in South Africa. Numerous submerged indigenous and invasive macrophyte locality records were collected during field surveys, of which many were first time records. Pet stores and aquarist trading activities were identified as potential vectors for the spread of submerged macrophytes through online surveys and personal interviews. These results highlighted the potential these species have for continuing to enter, and spread within South African water bodies. Maximum Entropy (MAXENT) is a general-purpose method used to predict or infer distributions from incomplete information, and was used here to predict areas suitable for the establishment of five of these invasive macrophytes. Many systems throughout South Africa, particularly those in the subtropical coastal regions, were found to be climatically suitable for the establishment of Elodea canadensis Michx., Egeria densa Planch., Hydrilla verticillata (L.f.) Royle (all Hydrocharitaceae), Myriophyllum spicatum L. (Haloragaceae), and Cabomba caroliniana Gray (Cabombaceae). Despite the high probability of invasion, facilitated by vectors and suitable climate, South Africa’s rich indigenous submerged aquatic flora may be preventing the establishment of these submerged invasive species. Studies on the competitive interactions between a common indigenous submerged macrophytes, Lagarosiphon major (Roxb.) (Hydrocharitaceae) and M.spicatum, an invasive native to Eurasia, were conducted to ascertain which conditions influence competitive superiority. High sediment nutrient conditions significantly increased the growth rate and competitive ability of both species, while clay sediments significantly increased the competitive ability of L. major over M. spicatum, but sandy sediments improved the competitive ability of M. spicatum. These results highlighted the dynamic changes in competition between submerged species driven by abiotic factors, but did not take into consideration the effect that herbivory, a biotic factor, could have on competition between the two species. The effect of herbivory by phytophagous insects of submerged plant species has been regarded as negligible. To find out what this effect is, multiple field surveys were undertaken throughout South Africa to find natural enemies of indigenous Lagarosiphon species with the aim of identifying such species, and quantifying their influence on plant growth dynamics. Several new phytophagous species were recorded for the first time. An ephydrid fly, Hydrellia lagarosiphon Deeming (Diptera: Ephydridae) was ascertained to be the most ubiquitous and abundant species associated with L. major in South Africa. The influence of herbivory by this fly on the competitive ability of L. major in the presence of M. spicatum was investigated using an inverse linear model, which showed that herbivory by H. lagarosiphon reduced the competitive ability of L. major by approximately five times in favour of M. spicatum. This study served to highlight the importance of herbivory as a driver of submerged aquatic plant dynamics. Current ecological theory emphasises the importance of investigating beyond plant-herbivore interactions, by including multitrophic interactions in community dynamics. Therefore, the potential of parasitism by a parasitoid wasp, Chaenusa luteostigma sp. n. Achterberg (Hymenoptera: Braconidae: Alysiinae) on H. lagarosiphon to shift the competitive interactions between the two plant species was also examined. The addition of the parasitoid reduced the effect of herbivory by the fly on L. major by half, thereby shifting the competitive balance in favour of L. major over M. spicatum. This study provides valuable insight into a selection of drivers of submerged macrophyte assemblages of South Africa. It highlights the precarious position of South African freshwater systems with regard to the potential invasion by damaging submerged invasive species. It also provides interesting insights into the effect of competition, herbivory and parasitism on the establishment and spread of species within submerged freshwater systems. Understanding the different influences could assist managers and policy makers to make validated decisions ensuring the integrity of South African freshwater systems.
- Full Text:
- Authors: Martin, Grant Douglas
- Date: 2013
- Subjects: Freshwater plants -- South Africa Aquatic weeds -- South Africa Invasive plants -- South Africa Freshwater ecology -- South Africa Biotic communities -- South Africa Maximum entropy method Lagarosiphon major -- South Africa Phytophagous insects -- South Africa Hydrellia -- South Africa Parasitoids -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5621 , http://hdl.handle.net/10962/d1004127
- Description: Potentially damaging submerged invasive freshwater macrophytes have been identified in South African freshwater systems, but have received less attention than their floating counterparts. To ascertain the changes and effects that these species may have on macrophyte ecology, an understanding of the drivers of macrophyte assemblages is essential. The aims of this thesis were to investigate select abiotic and biotic factors driving introduction, establishment and spread of submerged macrophytes in South Africa. Surveys on the status of submerged plant species in South Africa were conducted to find out the distribution and diversity of the species present, imported to, and traded in South Africa. Numerous submerged indigenous and invasive macrophyte locality records were collected during field surveys, of which many were first time records. Pet stores and aquarist trading activities were identified as potential vectors for the spread of submerged macrophytes through online surveys and personal interviews. These results highlighted the potential these species have for continuing to enter, and spread within South African water bodies. Maximum Entropy (MAXENT) is a general-purpose method used to predict or infer distributions from incomplete information, and was used here to predict areas suitable for the establishment of five of these invasive macrophytes. Many systems throughout South Africa, particularly those in the subtropical coastal regions, were found to be climatically suitable for the establishment of Elodea canadensis Michx., Egeria densa Planch., Hydrilla verticillata (L.f.) Royle (all Hydrocharitaceae), Myriophyllum spicatum L. (Haloragaceae), and Cabomba caroliniana Gray (Cabombaceae). Despite the high probability of invasion, facilitated by vectors and suitable climate, South Africa’s rich indigenous submerged aquatic flora may be preventing the establishment of these submerged invasive species. Studies on the competitive interactions between a common indigenous submerged macrophytes, Lagarosiphon major (Roxb.) (Hydrocharitaceae) and M.spicatum, an invasive native to Eurasia, were conducted to ascertain which conditions influence competitive superiority. High sediment nutrient conditions significantly increased the growth rate and competitive ability of both species, while clay sediments significantly increased the competitive ability of L. major over M. spicatum, but sandy sediments improved the competitive ability of M. spicatum. These results highlighted the dynamic changes in competition between submerged species driven by abiotic factors, but did not take into consideration the effect that herbivory, a biotic factor, could have on competition between the two species. The effect of herbivory by phytophagous insects of submerged plant species has been regarded as negligible. To find out what this effect is, multiple field surveys were undertaken throughout South Africa to find natural enemies of indigenous Lagarosiphon species with the aim of identifying such species, and quantifying their influence on plant growth dynamics. Several new phytophagous species were recorded for the first time. An ephydrid fly, Hydrellia lagarosiphon Deeming (Diptera: Ephydridae) was ascertained to be the most ubiquitous and abundant species associated with L. major in South Africa. The influence of herbivory by this fly on the competitive ability of L. major in the presence of M. spicatum was investigated using an inverse linear model, which showed that herbivory by H. lagarosiphon reduced the competitive ability of L. major by approximately five times in favour of M. spicatum. This study served to highlight the importance of herbivory as a driver of submerged aquatic plant dynamics. Current ecological theory emphasises the importance of investigating beyond plant-herbivore interactions, by including multitrophic interactions in community dynamics. Therefore, the potential of parasitism by a parasitoid wasp, Chaenusa luteostigma sp. n. Achterberg (Hymenoptera: Braconidae: Alysiinae) on H. lagarosiphon to shift the competitive interactions between the two plant species was also examined. The addition of the parasitoid reduced the effect of herbivory by the fly on L. major by half, thereby shifting the competitive balance in favour of L. major over M. spicatum. This study provides valuable insight into a selection of drivers of submerged macrophyte assemblages of South Africa. It highlights the precarious position of South African freshwater systems with regard to the potential invasion by damaging submerged invasive species. It also provides interesting insights into the effect of competition, herbivory and parasitism on the establishment and spread of species within submerged freshwater systems. Understanding the different influences could assist managers and policy makers to make validated decisions ensuring the integrity of South African freshwater systems.
- Full Text:
Dual-Catalyst Acceleration of Tandem Disulfide Cleavage and Baylis–Hillman Synthesis of 2 H-1-Benzothiopyran Derivatives
- Nyoni, Dubekile, Lobb, Kevin A, Kaye, Perry T
- Authors: Nyoni, Dubekile , Lobb, Kevin A , Kaye, Perry T
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448898 , vital:74769 , xlink:href="https://doi.org/10.1080/00397911.2012.673449"
- Description: While both 1,8-diazabicyclo[5.4.0]undec-7-ene and triphenylphosphine catalyze tandem Baylis–Hillman reaction/disulfide cleavage of 2,2′-dithiodibenzaldehyde independently, when used together as a dual-catalyst system, the overall yields of the cyclized 2H-1-benzothiopyrans are consistently greater and the reaction time decreases dramatically.
- Full Text:
- Authors: Nyoni, Dubekile , Lobb, Kevin A , Kaye, Perry T
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448898 , vital:74769 , xlink:href="https://doi.org/10.1080/00397911.2012.673449"
- Description: While both 1,8-diazabicyclo[5.4.0]undec-7-ene and triphenylphosphine catalyze tandem Baylis–Hillman reaction/disulfide cleavage of 2,2′-dithiodibenzaldehyde independently, when used together as a dual-catalyst system, the overall yields of the cyclized 2H-1-benzothiopyrans are consistently greater and the reaction time decreases dramatically.
- Full Text:
Dynamic geometry software as a dynamic tool for spatial exploration:
- Holzl, Reinhard, Schäfer, Marc
- Authors: Holzl, Reinhard , Schäfer, Marc
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140871 , vital:37925 , https://hdl.handle.net/10520/EJC146065
- Description: Dynamic Geometry Software (DGS) such as GeoGebra, Geometer's Sketchpad and Cabri Geometry offer a wealth of opportunities for an exploratory style of teaching and learning Mathematics, particularly in the exploration of space and shape. The new Curriculum and Assessment Policy Statement (CAPS) foregrounds the use of spatial skills and properties of shapes and objects "to identify, pose and solve problems creatively and critically" (South Africa. DBE, 2011, p. 9). Although the South African Mathematics curriculum no longer places importance on traditional Euclidean construction by means of straightedge and compass, DGS can nonetheless be used to engage with fundamental ideas relating to geometric shapes, symmetry and transformations. This was the impetus behind encouraging the use of GeoGebra in four township schools in the Grahamstown Education District whose Mathematics teachers participate in an ongoing in-service research and development programme hosted by Rhodes University.
- Full Text:
- Authors: Holzl, Reinhard , Schäfer, Marc
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140871 , vital:37925 , https://hdl.handle.net/10520/EJC146065
- Description: Dynamic Geometry Software (DGS) such as GeoGebra, Geometer's Sketchpad and Cabri Geometry offer a wealth of opportunities for an exploratory style of teaching and learning Mathematics, particularly in the exploration of space and shape. The new Curriculum and Assessment Policy Statement (CAPS) foregrounds the use of spatial skills and properties of shapes and objects "to identify, pose and solve problems creatively and critically" (South Africa. DBE, 2011, p. 9). Although the South African Mathematics curriculum no longer places importance on traditional Euclidean construction by means of straightedge and compass, DGS can nonetheless be used to engage with fundamental ideas relating to geometric shapes, symmetry and transformations. This was the impetus behind encouraging the use of GeoGebra in four township schools in the Grahamstown Education District whose Mathematics teachers participate in an ongoing in-service research and development programme hosted by Rhodes University.
- Full Text:
E-skills training on communal, fixed infrastructure as an activator of personal use of mobile internet
- Gumbo, Sibukelo, Terzoli, Alfredo
- Authors: Gumbo, Sibukelo , Terzoli, Alfredo
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430716 , vital:72710 , https://ieeexplore.ieee.org/abstract/document/6701781
- Description: In the second semester of 2012, training in computer literacy was of-fered in the Dwesa area, in deep rural South Africa, within the footprint of the Siyakhula Living Lab. Training of this nature is essential to make ICT access meaningful in such areas, and avoid wasteful `box drop-ping', unfortunately not uncommon. The training was done using com-munal fixed infrastructure located in schools but, interestingly, activated or deepened the use of mobile intemet among the people that attended the training. This paper contributes on the ongoing debate on whether mobile devices are the one and only solution to ICT access in rural (and peri-urban) poor settings in Africa.
- Full Text:
- Authors: Gumbo, Sibukelo , Terzoli, Alfredo
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430716 , vital:72710 , https://ieeexplore.ieee.org/abstract/document/6701781
- Description: In the second semester of 2012, training in computer literacy was of-fered in the Dwesa area, in deep rural South Africa, within the footprint of the Siyakhula Living Lab. Training of this nature is essential to make ICT access meaningful in such areas, and avoid wasteful `box drop-ping', unfortunately not uncommon. The training was done using com-munal fixed infrastructure located in schools but, interestingly, activated or deepened the use of mobile intemet among the people that attended the training. This paper contributes on the ongoing debate on whether mobile devices are the one and only solution to ICT access in rural (and peri-urban) poor settings in Africa.
- Full Text:
Ecological niche modeling of the invasive potential of Nile tilapia Oreochromis niloticus in African river systems: concerns and implications for the conservation of indigenous congenerics
- Zengeya, Tsungai A, Robertson, Mark P, Booth, Anthony J, Chimimba, Christian T
- Authors: Zengeya, Tsungai A , Robertson, Mark P , Booth, Anthony J , Chimimba, Christian T
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124341 , vital:35596 , https://doi.10.1007/s10530-012-0386-7
- Description: This study applied ecological niche models to determine the potential invasive range of Nile tilapia, Oreochromis niloticus, with a particular focus on river systems in southern Africa where it is now established and spreading. Computational tools such as niche models are useful in predicting the potential range of invasive species, but there are limitations to their application. In particular, models trained on native records may fail to predict the full extent of an invasion. This failure is often attributed to changes in either the niche of the invading species or the variables used to develop the models. In this study, we therefore evaluated the differences in the predictive power of models trained with different environmental variables, the effect of species range (native vs. introduced) on model performance and assessed whether or not there is evidence suggestive of a niche shift in Nile tilapia following its introduction. Niche models were constructed using Maxent and the degree of niche similarity was assessed using Schoener‘s index. Null models were used to test for significance. Model performance and niche conservatism varied significantly with variable selection and species range. This indicates that the environmental conditions available to Nile tilapia in its native and introduced ranges are not congruent. Nile tilapia exhibited broad invasive potential over most of southern Africa that overlaps the natural range of endemic congenerics. Of particular concern are areas which are free of exotic species but are now vulnerable due to the promotion of fish introductions mainly for aquaculture and sport fishing.
- Full Text:
- Authors: Zengeya, Tsungai A , Robertson, Mark P , Booth, Anthony J , Chimimba, Christian T
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124341 , vital:35596 , https://doi.10.1007/s10530-012-0386-7
- Description: This study applied ecological niche models to determine the potential invasive range of Nile tilapia, Oreochromis niloticus, with a particular focus on river systems in southern Africa where it is now established and spreading. Computational tools such as niche models are useful in predicting the potential range of invasive species, but there are limitations to their application. In particular, models trained on native records may fail to predict the full extent of an invasion. This failure is often attributed to changes in either the niche of the invading species or the variables used to develop the models. In this study, we therefore evaluated the differences in the predictive power of models trained with different environmental variables, the effect of species range (native vs. introduced) on model performance and assessed whether or not there is evidence suggestive of a niche shift in Nile tilapia following its introduction. Niche models were constructed using Maxent and the degree of niche similarity was assessed using Schoener‘s index. Null models were used to test for significance. Model performance and niche conservatism varied significantly with variable selection and species range. This indicates that the environmental conditions available to Nile tilapia in its native and introduced ranges are not congruent. Nile tilapia exhibited broad invasive potential over most of southern Africa that overlaps the natural range of endemic congenerics. Of particular concern are areas which are free of exotic species but are now vulnerable due to the promotion of fish introductions mainly for aquaculture and sport fishing.
- Full Text:
ECOMAG Model: an evaluation for use in South Africa
- Mokoena, M P, Kapangaziwiri, E, Kahinda, J M, Hughes, Denis A
- Authors: Mokoena, M P , Kapangaziwiri, E , Kahinda, J M , Hughes, Denis A
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438268 , vital:73447 , ISBN 978-1-4312-0408-3 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/TT%20555-13.pdf
- Description: The complexity of current approaches to water resource management poses many challenges. Water managers need to solve a range of interrelated water dilemmas, such as balancing water quantity and quality, flooding, drought, maintaining biodi-versity and ecological functions and the supply of water services to people. It is a sad fact in southern Africa that water availability is highly variable both spatially and temporally with low runoff coefficients of less than 9% conversion of mean annual precipitation (MAP) to mean annual runoff (MAR) known to be prevalent across large parts of the region (FAO, 2003). With predictions of water scarcity conditions, caused by rapid population growth, expanding urbanisation, increased economic development and climate change, (Rosegrant and Perez, 1997), water looks set to become a limiting resource in Southern Africa. The dynamics of demand and supply will have a large impact on the future socio-economic development of the region (Basson et al., 1997).
- Full Text:
- Authors: Mokoena, M P , Kapangaziwiri, E , Kahinda, J M , Hughes, Denis A
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438268 , vital:73447 , ISBN 978-1-4312-0408-3 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/TT%20555-13.pdf
- Description: The complexity of current approaches to water resource management poses many challenges. Water managers need to solve a range of interrelated water dilemmas, such as balancing water quantity and quality, flooding, drought, maintaining biodi-versity and ecological functions and the supply of water services to people. It is a sad fact in southern Africa that water availability is highly variable both spatially and temporally with low runoff coefficients of less than 9% conversion of mean annual precipitation (MAP) to mean annual runoff (MAR) known to be prevalent across large parts of the region (FAO, 2003). With predictions of water scarcity conditions, caused by rapid population growth, expanding urbanisation, increased economic development and climate change, (Rosegrant and Perez, 1997), water looks set to become a limiting resource in Southern Africa. The dynamics of demand and supply will have a large impact on the future socio-economic development of the region (Basson et al., 1997).
- Full Text:
Editorial. Methodology, Context and Quality
- Authors: Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387220 , vital:68216 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122254"
- Description: This edition of the Southern African Journal of Environmental Education (SAJEE) is a ‘double volume’ and contains papers submitted in 2012 and 2013. The production of a double volume has been necessitated by administrative problems experienced by the journal production team in 2012, which affected the successful publication of a 2012 edition. However, the Council of the Environmental Education Association of Southern Africa (EEASA) agreed to respond by producing a double-volume edition for 2012/2013. Journal readers are reminded that the production of this journal is voluntary and depends heavily on voluntary administration and other systems. The patience of authors and readers in the 2012/2013 years of production is much appreciated.
- Full Text:
- Authors: Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387220 , vital:68216 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122254"
- Description: This edition of the Southern African Journal of Environmental Education (SAJEE) is a ‘double volume’ and contains papers submitted in 2012 and 2013. The production of a double volume has been necessitated by administrative problems experienced by the journal production team in 2012, which affected the successful publication of a 2012 edition. However, the Council of the Environmental Education Association of Southern Africa (EEASA) agreed to respond by producing a double-volume edition for 2012/2013. Journal readers are reminded that the production of this journal is voluntary and depends heavily on voluntary administration and other systems. The patience of authors and readers in the 2012/2013 years of production is much appreciated.
- Full Text:
Editorial:
- Authors: Garman, Anthea
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158840 , vital:40233 , https://hdl.handle.net/10520/EJC141608
- Description: If you've been a Rhodes Journalism Review reader for a while, you'll be surprised by the smaller magazine you are holding in your hands right now. RJR started off life as an A4 but has been big since no 9, December 1994, and the size I inherited when I started as editor in 1997. It's a format I've always loved; it stands (er, stood) out among the wash of pamphlets at international conferences, it gave designers and photographers a fantastic sweep of canvas, and it was distinctive in the world of magazines, a true original.
- Full Text:
- Authors: Garman, Anthea
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158840 , vital:40233 , https://hdl.handle.net/10520/EJC141608
- Description: If you've been a Rhodes Journalism Review reader for a while, you'll be surprised by the smaller magazine you are holding in your hands right now. RJR started off life as an A4 but has been big since no 9, December 1994, and the size I inherited when I started as editor in 1997. It's a format I've always loved; it stands (er, stood) out among the wash of pamphlets at international conferences, it gave designers and photographers a fantastic sweep of canvas, and it was distinctive in the world of magazines, a true original.
- Full Text:
Editorial:
- Authors: Garman, Anthea
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158851 , vital:40234 , https://hdl.handle.net/10520/EJC141608
- Description: If you've been a Rhodes Journalism Review reader for a while, you'll be surprised by the smaller magazine you are holding in your hands right now. RJR started off life as an A4 but has been big since no 9, December 1994, and the size I inherited when I started as editor in 1997. It's a format I've always loved; it stands (er, stood) out among the wash of pamphlets at international conferences, it gave designers and photographers a fantastic sweep of canvas, and it was distinctive in the world of magazines, a true original.
- Full Text:
- Authors: Garman, Anthea
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158851 , vital:40234 , https://hdl.handle.net/10520/EJC141608
- Description: If you've been a Rhodes Journalism Review reader for a while, you'll be surprised by the smaller magazine you are holding in your hands right now. RJR started off life as an A4 but has been big since no 9, December 1994, and the size I inherited when I started as editor in 1997. It's a format I've always loved; it stands (er, stood) out among the wash of pamphlets at international conferences, it gave designers and photographers a fantastic sweep of canvas, and it was distinctive in the world of magazines, a true original.
- Full Text:
Effect of the relative humidity on the fibre morphology of polyamide 4.6 and polyamide 6.9 nanofibres
- De Schoenmaker, Bert, Van de Schueren, Lien, Zugle, Ruphino, Goethals, Annelies, Westbroek, Philippe, Kiekens, Paul, Nyokong, Tebello, De Clerck, Karen
- Authors: De Schoenmaker, Bert , Van de Schueren, Lien , Zugle, Ruphino , Goethals, Annelies , Westbroek, Philippe , Kiekens, Paul , Nyokong, Tebello , De Clerck, Karen
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242131 , vital:51004 , xlink:href="https://doi.org/10.1007/s10853-012-6934-9"
- Description: To obtain uniform and reproducible nanofibres, it is important to understand the effect of the different electrospinning parameters on the nanofibre morphology. Even though a lot of literature is available on the electrospinning of nanofibres, only minor research has been performed on the effect of the relative humidity (RH). This paper investigates the influence of this parameter on the electrospinning process and fibre morphology of the hydrophilic polyamide 4.6 and the less hydrophilic polyamide 6.9. First, the electrospinning process and deposition area of the nanofibres is examined at 10, 50 and 70 % RH. Subsequently, the effect of the polyamide concentration and solvent ratio on the fibre morphology is investigated using scanning electron microscopy and differential scanning calorimetry. It was found that the nanofibre diameter decreased with increasing RH. This resulted in less stable crystals for polyamide 4.6 while electrospinning of polyamide 6.9 at higher RH led to slightly more stable crystals. In conclusion, the water affinity of a polymer is an important factor in predicting the nanofibre morphology at different humidities.
- Full Text:
- Authors: De Schoenmaker, Bert , Van de Schueren, Lien , Zugle, Ruphino , Goethals, Annelies , Westbroek, Philippe , Kiekens, Paul , Nyokong, Tebello , De Clerck, Karen
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242131 , vital:51004 , xlink:href="https://doi.org/10.1007/s10853-012-6934-9"
- Description: To obtain uniform and reproducible nanofibres, it is important to understand the effect of the different electrospinning parameters on the nanofibre morphology. Even though a lot of literature is available on the electrospinning of nanofibres, only minor research has been performed on the effect of the relative humidity (RH). This paper investigates the influence of this parameter on the electrospinning process and fibre morphology of the hydrophilic polyamide 4.6 and the less hydrophilic polyamide 6.9. First, the electrospinning process and deposition area of the nanofibres is examined at 10, 50 and 70 % RH. Subsequently, the effect of the polyamide concentration and solvent ratio on the fibre morphology is investigated using scanning electron microscopy and differential scanning calorimetry. It was found that the nanofibre diameter decreased with increasing RH. This resulted in less stable crystals for polyamide 4.6 while electrospinning of polyamide 6.9 at higher RH led to slightly more stable crystals. In conclusion, the water affinity of a polymer is an important factor in predicting the nanofibre morphology at different humidities.
- Full Text:
Effects of gold nanoparticle shape on the aggregation and fluorescence behaviour of water soluble zinc phthalocyanines
- D'Souza, Sarah, Moeno, Sharon, Antunes, Edith M, Nyokong, Tebello
- Authors: D'Souza, Sarah , Moeno, Sharon , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232500 , vital:49997 , xlink:href="https://doi.org/10.1039/C3NJ00146F"
- Description: The absorption and fluorescence response as well as the fluorescence quantum yields and lifetimes of sulfonated phthalocyanines and alkyl carboxylic acid substituted zinc phthalocyanines in the presence of differently shaped water soluble gold nanoparticles were studied. The respective phthalocyanines are known to be highly aggregated in water, which is reported to markedly reduce the excited state lifetimes. This paper shows that in the presence of star shaped gold nanoparticles, the degree of phthalocyanine aggregation in water is greatly reduced, but the aggregation status of the phthalocyanines does not change for spherical Au nanoparticles. Since gold nanoparticles have already proven to be useful in numerous nanomedicinal and nanomedical applications, the disaggregation of phthalocyanines is an added advantage.
- Full Text:
- Authors: D'Souza, Sarah , Moeno, Sharon , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232500 , vital:49997 , xlink:href="https://doi.org/10.1039/C3NJ00146F"
- Description: The absorption and fluorescence response as well as the fluorescence quantum yields and lifetimes of sulfonated phthalocyanines and alkyl carboxylic acid substituted zinc phthalocyanines in the presence of differently shaped water soluble gold nanoparticles were studied. The respective phthalocyanines are known to be highly aggregated in water, which is reported to markedly reduce the excited state lifetimes. This paper shows that in the presence of star shaped gold nanoparticles, the degree of phthalocyanine aggregation in water is greatly reduced, but the aggregation status of the phthalocyanines does not change for spherical Au nanoparticles. Since gold nanoparticles have already proven to be useful in numerous nanomedicinal and nanomedical applications, the disaggregation of phthalocyanines is an added advantage.
- Full Text:
Electrocatalytic detection of pesticides with electrodes modified with nanoparticles of phthalocyanines and multiwalled carbon nanotubes
- Authors: Siswana, Msimelelo Patrick
- Date: 2013
- Subjects: Phthalocyanines Pesticides Electrocatalysis Electrochemistry Nanotubes Nanoparticles Transmission electron microscopy Scanning electron microscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4282 , http://hdl.handle.net/10962/d1002613
- Description: Three types of electrodes: carbon paste electrodes modified with nanoparticles of metallophthalocyanines (MPcNP-CPEs, M = Mn, Fe, Ni, Co), basal plane pyrolytic graphite electrodes modified with iron or nickel phthalocyanine nanoparticles and multiwalled carbon nanotube composites (FePcNP/MWCNT-BPPGE or NiPcNP/MWCNT-BPPGE),and basal plane pyrolytic graphite electrodes modified with multiwalled carbon nanotubes and electropolymerized metal tetra-aminophthalocyanines (poly-MTAPc-MWCNT-BPPGE), where M is Mn, Fe, Ni or Co, were prepared. Electrochemical characterizations showed that faster electron transfer kinetics occurred at the NiPcNP/MWCNT-BPPGE than at the FePcNP/MWCNT-BPPGE surface. SEM and electrochemical characterizations of poly-MTAPc-MWCNT-BPPGE showed that MTAPc had been deposited on the MWCNTBPPGE surface, and that the poly-CoTAPc-MWCNT-BPPGE exhibited the fastest electron transfer kinetics of all the poly-MTAPc-MWCNT-BPPGEs. Using amitrole and asulam as test analytes, electrochemical experiments showed that, amongst the CPEs, the FePcNP-CPE and NiPcNP-CPE displayed the most electrocatalytic behavior towards amitrole and asulam oxidation, respectively, and further experiments were done to obtain the electrochemical parameters associated with these electrodes and the corresponding analytes. Although, the FePcNP/MWCNT- BPPGE displayed electrocatalytic behavior towards amitrole oxidation in comparison with the bare BPPGE, it was less electrocatalytic than the FePcNP-CPE in terms of detection potential. The NiPcNP/MWCNT-BPPGE displayed the same detection potential as the NiPcNP-CPE. The poly-FeTAPc-MWCNT-BPPGE exhibited the most electrocatalytic behavior towards amitrole, of all the electrodes investigated, and the poly-CoTAPc-MWCNT-BPPGE displayed the best electrocatalytic behavior towards asulam, amongst the poly-MTAPc-MWCNT-BPPGEs.
- Full Text:
- Authors: Siswana, Msimelelo Patrick
- Date: 2013
- Subjects: Phthalocyanines Pesticides Electrocatalysis Electrochemistry Nanotubes Nanoparticles Transmission electron microscopy Scanning electron microscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4282 , http://hdl.handle.net/10962/d1002613
- Description: Three types of electrodes: carbon paste electrodes modified with nanoparticles of metallophthalocyanines (MPcNP-CPEs, M = Mn, Fe, Ni, Co), basal plane pyrolytic graphite electrodes modified with iron or nickel phthalocyanine nanoparticles and multiwalled carbon nanotube composites (FePcNP/MWCNT-BPPGE or NiPcNP/MWCNT-BPPGE),and basal plane pyrolytic graphite electrodes modified with multiwalled carbon nanotubes and electropolymerized metal tetra-aminophthalocyanines (poly-MTAPc-MWCNT-BPPGE), where M is Mn, Fe, Ni or Co, were prepared. Electrochemical characterizations showed that faster electron transfer kinetics occurred at the NiPcNP/MWCNT-BPPGE than at the FePcNP/MWCNT-BPPGE surface. SEM and electrochemical characterizations of poly-MTAPc-MWCNT-BPPGE showed that MTAPc had been deposited on the MWCNTBPPGE surface, and that the poly-CoTAPc-MWCNT-BPPGE exhibited the fastest electron transfer kinetics of all the poly-MTAPc-MWCNT-BPPGEs. Using amitrole and asulam as test analytes, electrochemical experiments showed that, amongst the CPEs, the FePcNP-CPE and NiPcNP-CPE displayed the most electrocatalytic behavior towards amitrole and asulam oxidation, respectively, and further experiments were done to obtain the electrochemical parameters associated with these electrodes and the corresponding analytes. Although, the FePcNP/MWCNT- BPPGE displayed electrocatalytic behavior towards amitrole oxidation in comparison with the bare BPPGE, it was less electrocatalytic than the FePcNP-CPE in terms of detection potential. The NiPcNP/MWCNT-BPPGE displayed the same detection potential as the NiPcNP-CPE. The poly-FeTAPc-MWCNT-BPPGE exhibited the most electrocatalytic behavior towards amitrole, of all the electrodes investigated, and the poly-CoTAPc-MWCNT-BPPGE displayed the best electrocatalytic behavior towards asulam, amongst the poly-MTAPc-MWCNT-BPPGEs.
- Full Text:
Electrochemical impedimetric immunosensor for the detection of measles-specific IgG antibodies after measles infections
- Mashazi, Philani N, Tetyana, Phumlani, Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Mashazi, Philani N , Tetyana, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241677 , vital:50960 , xlink:href="https://doi.org/10.1016/j.bios.2013.04.028"
- Description: The detection of measles-specific primary antibodies (IgG) using electrochemical impedimetric immunosensors is reported. The optimum conditions for electrode saturation were reached after 40 min for 1 μg ml−1 antibody concentrations. Surface roughness using AFM increased with each immobilization or antigen-antibody reaction step clearly confirming the surface modification and recognition between antigen and antibody. The human serum (HS) and new-born calf serum (NCS) spiked with antigen-specific antibody were studied to mimic the real sample analysis. The HS and NCS sera containing antibodies due to measles exhibited correlation between the increasing antibody serum concentrations and the charge-transfer resistance (electrochemically measured). This work clearly showed the potential use of impedance as the preferred electrochemical method for detecting measles-antibodies in label-free manner.
- Full Text:
- Authors: Mashazi, Philani N , Tetyana, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241677 , vital:50960 , xlink:href="https://doi.org/10.1016/j.bios.2013.04.028"
- Description: The detection of measles-specific primary antibodies (IgG) using electrochemical impedimetric immunosensors is reported. The optimum conditions for electrode saturation were reached after 40 min for 1 μg ml−1 antibody concentrations. Surface roughness using AFM increased with each immobilization or antigen-antibody reaction step clearly confirming the surface modification and recognition between antigen and antibody. The human serum (HS) and new-born calf serum (NCS) spiked with antigen-specific antibody were studied to mimic the real sample analysis. The HS and NCS sera containing antibodies due to measles exhibited correlation between the increasing antibody serum concentrations and the charge-transfer resistance (electrochemically measured). This work clearly showed the potential use of impedance as the preferred electrochemical method for detecting measles-antibodies in label-free manner.
- Full Text:
Electrospun fibers functionalized with phthalocyanine-gold nanoparticle conjugates for photocatalytic applications
- Tombe, Sekai, Antunes, Edith M, Nyokong, Tebello
- Authors: Tombe, Sekai , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193769 , vital:45394 , xlink:href="https://doi.org/10.1016/j.molcata.2013.01.033"
- Description: The heterogeneous photocatalytic activity of Zn(II) phthalocyanine-gold nanoparticle conjugates immobilized on electrospun polystyrene fibers was investigated using 4-chlorophenol and Orange G as model pollutants. The phthalocyanine-gold nanoparticle conjugates were synthesized via a ligand exchange reaction and characterized using spectroscopic and microscopic techniques. The interaction between the gold nanoparticles and phthalocyanines did not restrict the formation of excited singlet states, triplet states and hence the formation of singlet oxygen required for photocatalysis. The conjugates showed significantly higher singlet oxygen quantum yields and enhanced photocatalytic activity compared to the phthalocyanines. It was concluded that hybrid electrospun fibers provide great potential as active photocatalysts for oxidizing organic pollutants using singlet oxygen as an oxidant.
- Full Text:
- Authors: Tombe, Sekai , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193769 , vital:45394 , xlink:href="https://doi.org/10.1016/j.molcata.2013.01.033"
- Description: The heterogeneous photocatalytic activity of Zn(II) phthalocyanine-gold nanoparticle conjugates immobilized on electrospun polystyrene fibers was investigated using 4-chlorophenol and Orange G as model pollutants. The phthalocyanine-gold nanoparticle conjugates were synthesized via a ligand exchange reaction and characterized using spectroscopic and microscopic techniques. The interaction between the gold nanoparticles and phthalocyanines did not restrict the formation of excited singlet states, triplet states and hence the formation of singlet oxygen required for photocatalysis. The conjugates showed significantly higher singlet oxygen quantum yields and enhanced photocatalytic activity compared to the phthalocyanines. It was concluded that hybrid electrospun fibers provide great potential as active photocatalysts for oxidizing organic pollutants using singlet oxygen as an oxidant.
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Engineering Education Research for educational change: the possibilities of critical realism for conceptualising causal mechanicsms in education
- Case, Jennifer, Blackie, Margaret A L
- Authors: Case, Jennifer , Blackie, Margaret A L
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426637 , vital:72374 , xlink:href="https://doi.org/10.1016/j.biocontrol.2013.07.023"
- Description: Engineering Education Research (EER) grew in prominence from the late 1990s as purposes for this field were espoused in relation to the necessity of change for engineering education in the newly globalising world. Arguments centred on overall challenges with recruitment to engineering, specifically in relation to historically underrepresented populations, as well as with the forms of education (both in terms of quality of teaching and relevance of curricula) offered to students, and the needs of employers as reflected in newly-emerged global accreditation systems. In a field that is at least partly directed towards educational change, there is a need to understand how change typically happens in education systems. This article first draws on findings from the sociology of education to show that causality in relation to educational change is complex. It then turns to the philosophy of critical realism for a way of thinking about change that can inform EER, and concludes by outlining how this might change the research questions that drive the field, and how these might be approached.
- Full Text:
- Authors: Case, Jennifer , Blackie, Margaret A L
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426637 , vital:72374 , xlink:href="https://doi.org/10.1016/j.biocontrol.2013.07.023"
- Description: Engineering Education Research (EER) grew in prominence from the late 1990s as purposes for this field were espoused in relation to the necessity of change for engineering education in the newly globalising world. Arguments centred on overall challenges with recruitment to engineering, specifically in relation to historically underrepresented populations, as well as with the forms of education (both in terms of quality of teaching and relevance of curricula) offered to students, and the needs of employers as reflected in newly-emerged global accreditation systems. In a field that is at least partly directed towards educational change, there is a need to understand how change typically happens in education systems. This article first draws on findings from the sociology of education to show that causality in relation to educational change is complex. It then turns to the philosophy of critical realism for a way of thinking about change that can inform EER, and concludes by outlining how this might change the research questions that drive the field, and how these might be approached.
- Full Text:
Entomopathogenic fungi for control of soil-borne life stages of false codling moth, Thaumatotibia leucotreta (Meyrick) (1912) (Lepidoptera: Tortricidae)
- Authors: Coombes, Candice Anne
- Date: 2013
- Subjects: Tortricidae , Lepidoptera , Cryptophlebia leucotreta , Insect pests -- Biological control -- South Africa -- Eastern Cape , Tortricidae -- Biological control -- South Africa -- Eastern Cape , Citrus -- Diseases and pests -- Biological control -- South Africa -- Eastern Cape , Entomopathogenic fungi , Fungi as biological pest control agents , Biological pest control agents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5607 , http://hdl.handle.net/10962/d1002057 , Tortricidae , Lepidoptera , Cryptophlebia leucotreta , Insect pests -- Biological control -- South Africa -- Eastern Cape , Tortricidae -- Biological control -- South Africa -- Eastern Cape , Citrus -- Diseases and pests -- Biological control -- South Africa -- Eastern Cape , Entomopathogenic fungi , Fungi as biological pest control agents , Biological pest control agents
- Description: False codling moth (FCM), Thaumatotibia leucotreta is an extremely important pest of citrus in South Africa and with the shift away from the use of chemicals, alternate control options are needed. One avenue of control which has only recently been investigated against the soil-borne life stages of FCM is the use of entomopathogenic fungi (EPF). In 2009, 12 entomopathogenic fungal isolates collected from South African citrus orchards showed good control potential during laboratory conducted bioassays. The aim of this study was to further analyse the potential of these isolates through concentration-dose and exposure-time response bioassays. After initial re-screening, concentration-dose response and exposure-time response sandconidial bioassays, three isolates were identified as exhibiting the greatest control potential against FCM in soil, Metarhizium anisopliae var. anisopliae (G 11 3 L6 and FCM Ar 23 B3) and Beauveria bassiana (G Ar 17 B3). Percentage mycosis was found to be directly related to fungal concentration as well as the amount of time FCM 5th instar larvae were exposed to the fungal conidia. LC50 values for the three isolates were not greater than 1.92 x 10⁶ conidia.ml⁻ₑ and at the LC₅₀, FCM 5th instar larvae would need to be exposed to the fungus for a maximum of 13 days to ensure a high mortality level. These isolates along with two commercially available EPF products were subjected to field persistence trials whereby net bags filled with a mixture of autoclaved sand and formulated fungal product were buried in an Eastern Cape citrus orchard. The viability of each isolate was measured on a monthly basis for a period of six months. All isolates were capable of persisting in the soil for six months with the collected isolates persisting far better than the commercially used isolates. Two of the isolates, G 11 3 L6 and G Ar 17 B3, were subjected to small scale laboratory application trials. Two formulations were investigated at two concentrations. For each isolate, each formulation and each concentration, FCM 5th instar larvae were applied and allowed to burrow into the soil to pupate before fungal application or after fungal application. Contact between fungi and FCM host is essential as, in contrast to pre-larval treatments, percentage mortality in post-larval treatments was low for both formulations and both isolates. For isolate G Ar 17 B3, a conidial suspension applied as a spray at a concentration of 1 x 10⁷ conidia.ml⁻ₑ obtained the highest percentage mortality (80 %). For isolate G 11 3 L6 however, both formulations performed equally well at a high, 1 x10⁷ conidia.ml⁻ₑ concentration (conidial suspension: 60 %; granular: 65 %) The results obtained thus far are promising for the control of FCM in citrus, but if these EPFs are to successfully integrate into current FCM control practices more research, some of which is discussed, is essential
- Full Text:
- Authors: Coombes, Candice Anne
- Date: 2013
- Subjects: Tortricidae , Lepidoptera , Cryptophlebia leucotreta , Insect pests -- Biological control -- South Africa -- Eastern Cape , Tortricidae -- Biological control -- South Africa -- Eastern Cape , Citrus -- Diseases and pests -- Biological control -- South Africa -- Eastern Cape , Entomopathogenic fungi , Fungi as biological pest control agents , Biological pest control agents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5607 , http://hdl.handle.net/10962/d1002057 , Tortricidae , Lepidoptera , Cryptophlebia leucotreta , Insect pests -- Biological control -- South Africa -- Eastern Cape , Tortricidae -- Biological control -- South Africa -- Eastern Cape , Citrus -- Diseases and pests -- Biological control -- South Africa -- Eastern Cape , Entomopathogenic fungi , Fungi as biological pest control agents , Biological pest control agents
- Description: False codling moth (FCM), Thaumatotibia leucotreta is an extremely important pest of citrus in South Africa and with the shift away from the use of chemicals, alternate control options are needed. One avenue of control which has only recently been investigated against the soil-borne life stages of FCM is the use of entomopathogenic fungi (EPF). In 2009, 12 entomopathogenic fungal isolates collected from South African citrus orchards showed good control potential during laboratory conducted bioassays. The aim of this study was to further analyse the potential of these isolates through concentration-dose and exposure-time response bioassays. After initial re-screening, concentration-dose response and exposure-time response sandconidial bioassays, three isolates were identified as exhibiting the greatest control potential against FCM in soil, Metarhizium anisopliae var. anisopliae (G 11 3 L6 and FCM Ar 23 B3) and Beauveria bassiana (G Ar 17 B3). Percentage mycosis was found to be directly related to fungal concentration as well as the amount of time FCM 5th instar larvae were exposed to the fungal conidia. LC50 values for the three isolates were not greater than 1.92 x 10⁶ conidia.ml⁻ₑ and at the LC₅₀, FCM 5th instar larvae would need to be exposed to the fungus for a maximum of 13 days to ensure a high mortality level. These isolates along with two commercially available EPF products were subjected to field persistence trials whereby net bags filled with a mixture of autoclaved sand and formulated fungal product were buried in an Eastern Cape citrus orchard. The viability of each isolate was measured on a monthly basis for a period of six months. All isolates were capable of persisting in the soil for six months with the collected isolates persisting far better than the commercially used isolates. Two of the isolates, G 11 3 L6 and G Ar 17 B3, were subjected to small scale laboratory application trials. Two formulations were investigated at two concentrations. For each isolate, each formulation and each concentration, FCM 5th instar larvae were applied and allowed to burrow into the soil to pupate before fungal application or after fungal application. Contact between fungi and FCM host is essential as, in contrast to pre-larval treatments, percentage mortality in post-larval treatments was low for both formulations and both isolates. For isolate G Ar 17 B3, a conidial suspension applied as a spray at a concentration of 1 x 10⁷ conidia.ml⁻ₑ obtained the highest percentage mortality (80 %). For isolate G 11 3 L6 however, both formulations performed equally well at a high, 1 x10⁷ conidia.ml⁻ₑ concentration (conidial suspension: 60 %; granular: 65 %) The results obtained thus far are promising for the control of FCM in citrus, but if these EPFs are to successfully integrate into current FCM control practices more research, some of which is discussed, is essential
- Full Text:
Environmental domains and range-limiting mechanisms: testing the Abundant Centre Hypothesis using southern African sandhoppers
- Baldanzi, Simone, McQuaid, Christopher D, Cannicci, Stefano, Porri, Francesca
- Authors: Baldanzi, Simone , McQuaid, Christopher D , Cannicci, Stefano , Porri, Francesca
- Date: 2013
- Language: English
- Type: Article
- Identifier: vital:6848 , http://hdl.handle.net/10962/d1011108
- Description: Predicting shifts of species geographical ranges is a fundamental challenge for conservation ecologists given the great complexity of factors involved in setting range limits. Distributional patterns are frequently modelled to “simplify” species responses to the environment, yet the central mechanisms that drive a particular pattern are rarely understood. We evaluated the distributions of two sandhopper species (Crustacea, Amphipoda, Talitridae), Talorchestia capensis and Africorchestia quadrispinosa along the Namibian and South African coasts, encompassing three biogeographic regions influenced by two different oceanographic systems, the Benguela and Agulhas currents. We aimed to test whether the Abundant Centre Hypothesis (ACH) can explain the distributions of these species’ abundances, sizes and sex ratios and examined which environmental parameters influence/drive these distributions. Animals were collected during a once-off survey at 29 sites over c.3500 km of coastline. The ACH was tested using a non-parametric constraint space analysis of the goodness of fit of five hypothetical models. Distance Based Linear Modelling (DistLM) was performed to evaluate which environmental traits influenced the distribution data. Abundance, size and sex ratio showed different patterns of distribution. A ramped model fitted the abundance (Ramped North) and size (Ramped South) distribution for A. quadrispinosa. The Inverse Quadratic model fitted the size distribution of T. capensis. Beach slope, salinity, sand temperature and percentage of detritus found on the shore at the time of collection played important roles in driving the abundance of A. quadrispinosa. T. capensis was mainly affected by salinity and the morphodynamic state of the beach. Our results provided only some support for the ACH predictions. The DistLM confirmed that the physical state of the beach is an important factor for sandy beach organisms. The effect of salinity and temperature suggest metabolic responses to local conditions and a role in small to mesoscale shifts in the range of these populations.
- Full Text:
- Authors: Baldanzi, Simone , McQuaid, Christopher D , Cannicci, Stefano , Porri, Francesca
- Date: 2013
- Language: English
- Type: Article
- Identifier: vital:6848 , http://hdl.handle.net/10962/d1011108
- Description: Predicting shifts of species geographical ranges is a fundamental challenge for conservation ecologists given the great complexity of factors involved in setting range limits. Distributional patterns are frequently modelled to “simplify” species responses to the environment, yet the central mechanisms that drive a particular pattern are rarely understood. We evaluated the distributions of two sandhopper species (Crustacea, Amphipoda, Talitridae), Talorchestia capensis and Africorchestia quadrispinosa along the Namibian and South African coasts, encompassing three biogeographic regions influenced by two different oceanographic systems, the Benguela and Agulhas currents. We aimed to test whether the Abundant Centre Hypothesis (ACH) can explain the distributions of these species’ abundances, sizes and sex ratios and examined which environmental parameters influence/drive these distributions. Animals were collected during a once-off survey at 29 sites over c.3500 km of coastline. The ACH was tested using a non-parametric constraint space analysis of the goodness of fit of five hypothetical models. Distance Based Linear Modelling (DistLM) was performed to evaluate which environmental traits influenced the distribution data. Abundance, size and sex ratio showed different patterns of distribution. A ramped model fitted the abundance (Ramped North) and size (Ramped South) distribution for A. quadrispinosa. The Inverse Quadratic model fitted the size distribution of T. capensis. Beach slope, salinity, sand temperature and percentage of detritus found on the shore at the time of collection played important roles in driving the abundance of A. quadrispinosa. T. capensis was mainly affected by salinity and the morphodynamic state of the beach. Our results provided only some support for the ACH predictions. The DistLM confirmed that the physical state of the beach is an important factor for sandy beach organisms. The effect of salinity and temperature suggest metabolic responses to local conditions and a role in small to mesoscale shifts in the range of these populations.
- Full Text:
Environmental ethics as processes of open-ended, pluralistic, deliberative enquiry
- Authors: Olvitt, Lausanne L
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437309 , vital:73368 , ISBN 9780203813331 , https://www.taylorfrancis.com/chapters/edit/10.4324/9780203813331-15/environmental-ethics-processes-open-ended-pluralistic-deliberative-enquiry-lausanne-olvitt
- Description: By the very nature of their work, environmental education re-searchers must engage with environmental philosophy and questions of values and ethics. But this terrain, despite being resourced with an apparently endless supply of typologies, an-thologies, and handbooks, can remain a vast and daunting philosophical sea—at least in my experience as a newcomer to the field, and possibly for many other scholars and re-searchers. This essay makes no claim to altering that and in-stead optimistically pursues Ball’s (2001, p. 89) suggestion that “there is much to be learned about, and from, the philosophical life-forms inhabiting these thickets and swamps.” My intention here is to review a relatively small but growing cluster of work in environmental ethics that proposes that:“Ethical positions are always open for discussion, re-examination, and revi-sion”(Jickling, 2004, p. 16) and are thus, by their very nature, open-ended, relational processes. My starting point in writing this essay is as an educator-researcher-environmentalist trying to explore what the field of environmental ethics has to offer in response to the question:“As educators, how can we learn and do more with others in the face of an unprecedented socioeco-logical crisis?”
- Full Text:
- Authors: Olvitt, Lausanne L
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437309 , vital:73368 , ISBN 9780203813331 , https://www.taylorfrancis.com/chapters/edit/10.4324/9780203813331-15/environmental-ethics-processes-open-ended-pluralistic-deliberative-enquiry-lausanne-olvitt
- Description: By the very nature of their work, environmental education re-searchers must engage with environmental philosophy and questions of values and ethics. But this terrain, despite being resourced with an apparently endless supply of typologies, an-thologies, and handbooks, can remain a vast and daunting philosophical sea—at least in my experience as a newcomer to the field, and possibly for many other scholars and re-searchers. This essay makes no claim to altering that and in-stead optimistically pursues Ball’s (2001, p. 89) suggestion that “there is much to be learned about, and from, the philosophical life-forms inhabiting these thickets and swamps.” My intention here is to review a relatively small but growing cluster of work in environmental ethics that proposes that:“Ethical positions are always open for discussion, re-examination, and revi-sion”(Jickling, 2004, p. 16) and are thus, by their very nature, open-ended, relational processes. My starting point in writing this essay is as an educator-researcher-environmentalist trying to explore what the field of environmental ethics has to offer in response to the question:“As educators, how can we learn and do more with others in the face of an unprecedented socioeco-logical crisis?”
- Full Text: