Dependence on environmental resources and implications for household welfare: evidence from the Kalahari drylands, South Africa
- Thondhlana, Gladman, Muchapondwa, Edwin
- Authors: Thondhlana, Gladman , Muchapondwa, Edwin
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67810 , vital:29149 , https://doi.org/10.1016/j.ecolecon.2014.10.003
- Description: Publisher version , This paper examines dependence on environmental resources and impacts on household welfare among the indigenous San and Mier rural communities neighbouring Kgalagadi Transfrontier Park in South Africa. Data on the various household income types, including environmental income, were collected through a structured survey of 200 households. Environmental income constituted 20% of the total income. The poorest income quintile showed the highest relative dependence on environmental income (31%), though absolute environmental income increased with total income. Poverty analyses showed that poverty incidence and poverty gap would increase by 13 and 7 percentage points respectively without environmental income. Gini-coefficient analyses revealed that income inequality would increase by 6 percentage points for all households if environmental income was excluded. The results generally suggest that environmental income is important for both the poor and the well-off, and wealth accumulation might be tied to resource use. There is a case for promoting sound environmental management, and sustainable and fair resource use in the Kalahari drylands in order to help pull more households out of poverty. Our findings also point to issues of heterogeneity in resource access even among indigenous communities previously thought to be homogenous. These should be key considerations for conservation interventions.
- Full Text: false
- Date Issued: 2014
- Authors: Thondhlana, Gladman , Muchapondwa, Edwin
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67810 , vital:29149 , https://doi.org/10.1016/j.ecolecon.2014.10.003
- Description: Publisher version , This paper examines dependence on environmental resources and impacts on household welfare among the indigenous San and Mier rural communities neighbouring Kgalagadi Transfrontier Park in South Africa. Data on the various household income types, including environmental income, were collected through a structured survey of 200 households. Environmental income constituted 20% of the total income. The poorest income quintile showed the highest relative dependence on environmental income (31%), though absolute environmental income increased with total income. Poverty analyses showed that poverty incidence and poverty gap would increase by 13 and 7 percentage points respectively without environmental income. Gini-coefficient analyses revealed that income inequality would increase by 6 percentage points for all households if environmental income was excluded. The results generally suggest that environmental income is important for both the poor and the well-off, and wealth accumulation might be tied to resource use. There is a case for promoting sound environmental management, and sustainable and fair resource use in the Kalahari drylands in order to help pull more households out of poverty. Our findings also point to issues of heterogeneity in resource access even among indigenous communities previously thought to be homogenous. These should be key considerations for conservation interventions.
- Full Text: false
- Date Issued: 2014
Designing writing groups to support postgraduate students’ academic writing: a case study from a South African university
- Authors: Wilmot, Kirstin
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66267 , vital:28926 , https://doi.org/10.1080/14703297.2016.1238775
- Description: publisher version , This paper reports on a writing group pilot programme implemented at a South African university. Drawing on literature, anonymous student evaluations and facilitator observations, it discusses the use of writing groups for supporting postgraduate academic writing practices. Developed within a broader postgraduate academic writing support programme, the paper discusses a case study of two pilot writing groups: a multidisciplinary long-term group and a disciplinary short-term ‘writing-intensive’ group. The findings indicate that the overall experience of the writing group was a positive one, with each group presenting varied ‘success’ aspects as well as challenges. Insights gleaned may contribute to our understanding of how these groups can be utilised to support postgraduate students and how different kinds of groups can be developed to serve particular student needs. The paper concludes with a discussion of the inclusion of a disciplinary expert, which proved particularly useful in this pilot.
- Full Text: false
- Date Issued: 2018
- Authors: Wilmot, Kirstin
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66267 , vital:28926 , https://doi.org/10.1080/14703297.2016.1238775
- Description: publisher version , This paper reports on a writing group pilot programme implemented at a South African university. Drawing on literature, anonymous student evaluations and facilitator observations, it discusses the use of writing groups for supporting postgraduate academic writing practices. Developed within a broader postgraduate academic writing support programme, the paper discusses a case study of two pilot writing groups: a multidisciplinary long-term group and a disciplinary short-term ‘writing-intensive’ group. The findings indicate that the overall experience of the writing group was a positive one, with each group presenting varied ‘success’ aspects as well as challenges. Insights gleaned may contribute to our understanding of how these groups can be utilised to support postgraduate students and how different kinds of groups can be developed to serve particular student needs. The paper concludes with a discussion of the inclusion of a disciplinary expert, which proved particularly useful in this pilot.
- Full Text: false
- Date Issued: 2018
Docking of HIV protease to silver nanoparticles
- Whiteley, Chris G, Shing, C-Y, Kuo, C-C, Lee, Duu-Jong
- Authors: Whiteley, Chris G , Shing, C-Y , Kuo, C-C , Lee, Duu-Jong
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67105 , vital:29032 , https://doi.org/10.1016/j.jtice.2015.10.029
- Description: publisher version , This interaction of silver nanoparticles (AgNP) with human immune-deficiency virus aspartic protease (HIVPR) is examined by molecular dynamics simulation using the Colores (Situs) package and biophysical techniques using UV–vis spectroscopy, dynamic light scattering, transmission electron microscopy and circular dichroism. The ‘docking’ of AgNP with HIVPR creates a complex [AgNP–HIVPR] to initiate a hypochromic time-dependent red-shift for the surface plasmon resonance maximum. MD simulations reflect large perturbations to enzyme conformations by fluctuations of both rmsd and B-factors. Increase in changes to electrostatic potentials within the enzyme, especially, with chain B, suggest hydrophobic interactions for the binding of the AgNP. This is supported by changes to mainchain and sidechain dihedrals for many hydrophobic amino acid including Cys95, Trp6 and Trp42. Circular dichroism spectra reveal disappearance of α-helices and β-sheets and increase in random coil first from chain B then chain A. During initial stages of the interactive simulation the enzyme is conformational flexible to accommodate the AgNP, that docks with the enzyme under a cooperative mechanism, until a more stable structure is formed at convergence. There is a decrease in size of the HIVPR–AgNP complex measured by changes to the gyration radius supporting evidence that the AgNP associates, initially, with chain B.
- Full Text: false
- Date Issued: 2016
- Authors: Whiteley, Chris G , Shing, C-Y , Kuo, C-C , Lee, Duu-Jong
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67105 , vital:29032 , https://doi.org/10.1016/j.jtice.2015.10.029
- Description: publisher version , This interaction of silver nanoparticles (AgNP) with human immune-deficiency virus aspartic protease (HIVPR) is examined by molecular dynamics simulation using the Colores (Situs) package and biophysical techniques using UV–vis spectroscopy, dynamic light scattering, transmission electron microscopy and circular dichroism. The ‘docking’ of AgNP with HIVPR creates a complex [AgNP–HIVPR] to initiate a hypochromic time-dependent red-shift for the surface plasmon resonance maximum. MD simulations reflect large perturbations to enzyme conformations by fluctuations of both rmsd and B-factors. Increase in changes to electrostatic potentials within the enzyme, especially, with chain B, suggest hydrophobic interactions for the binding of the AgNP. This is supported by changes to mainchain and sidechain dihedrals for many hydrophobic amino acid including Cys95, Trp6 and Trp42. Circular dichroism spectra reveal disappearance of α-helices and β-sheets and increase in random coil first from chain B then chain A. During initial stages of the interactive simulation the enzyme is conformational flexible to accommodate the AgNP, that docks with the enzyme under a cooperative mechanism, until a more stable structure is formed at convergence. There is a decrease in size of the HIVPR–AgNP complex measured by changes to the gyration radius supporting evidence that the AgNP associates, initially, with chain B.
- Full Text: false
- Date Issued: 2016
Encouraging pro-environmental behaviour: energy use and recycling at Rhodes University, South Africa
- Mtutu, Paidamoyo, Thondhlana, Gladman
- Authors: Mtutu, Paidamoyo , Thondhlana, Gladman
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67743 , vital:29136 , https://doi.org/10.1016/j.habitatint.2015.11.031
- Description: Publisher version , The rapid expansion of student numbers, staff and support infrastructures in higher education institutions often result in increased demand for resources such as energy and paper. Promoting pro-environmental behaviour is critical if higher education institutions are to achieve sustainable resource use. Using surveys, reported energy use and recycling behaviour of staff and students in the Faculty of Education at Rhodes University, South Africa was explored. The results showed that self-reported pro-environmental behaviour was mediated by demographic factors and personal values such as ‘liking of aesthetic beauty and biodiversity’, ‘social relations’, ‘a varied life’ and ‘freedom’. Personal values, though key in shaping participants' attitudes toward the environment did not always translate into pro-environmental behaviour. Situational factors beyond the control of participants were cited as barriers to pro-environmental actions. Lessons from this study point to the need to carefully study the assumptions underlying intervention strategies aimed at promoting pro-environmental behaviour and to get rid of barriers to enable pro-environmental actions.
- Full Text: false
- Date Issued: 2016
Encouraging pro-environmental behaviour: energy use and recycling at Rhodes University, South Africa
- Authors: Mtutu, Paidamoyo , Thondhlana, Gladman
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67743 , vital:29136 , https://doi.org/10.1016/j.habitatint.2015.11.031
- Description: Publisher version , The rapid expansion of student numbers, staff and support infrastructures in higher education institutions often result in increased demand for resources such as energy and paper. Promoting pro-environmental behaviour is critical if higher education institutions are to achieve sustainable resource use. Using surveys, reported energy use and recycling behaviour of staff and students in the Faculty of Education at Rhodes University, South Africa was explored. The results showed that self-reported pro-environmental behaviour was mediated by demographic factors and personal values such as ‘liking of aesthetic beauty and biodiversity’, ‘social relations’, ‘a varied life’ and ‘freedom’. Personal values, though key in shaping participants' attitudes toward the environment did not always translate into pro-environmental behaviour. Situational factors beyond the control of participants were cited as barriers to pro-environmental actions. Lessons from this study point to the need to carefully study the assumptions underlying intervention strategies aimed at promoting pro-environmental behaviour and to get rid of barriers to enable pro-environmental actions.
- Full Text: false
- Date Issued: 2016
Local institutions, actors, and natural resource governance in Kgalagadi Transfrontier Park and surrounds, South Africa
- Thondhlana, Gladman, Shackleton, Sheona E, Blignaut, James
- Authors: Thondhlana, Gladman , Shackleton, Sheona E , Blignaut, James
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67689 , vital:29130 , https://doi.org/10.1016/j.landusepol.2015.03.013
- Description: Publisher version , Crafting local institutions to allow more effective decision-making in the management of and access to natural resources in and beyond parks has long been considered key to collaborative governance. South Africa, in particular, has vigorously pursued collaborative governance as a desired approach to managing natural resources as evident in the new arrangements for previously restricted parks. However, though the discourse of collaborative governance has occupied conservation thinking and practice globally, few studies have looked at the interplay between local institutions, actors and collaborative governance involving indigenous hunter–gatherer communities in Southern Africa. In response, we assess the local actors and institutions that were put in place to facilitate collaborative governance of natural resources in the Kgalagadi Transfrontier Park and its surrounds in South Africa. Our findings show that though collaborative governance has a practical appeal, it is hampered by lack of participation in decision-making, information dissemination, transparency, trust and accountability, power relations, divergent interests and unequal access to natural resources. The findings also draw our attention to issues of heterogeneity, even within indigenous communities assumed to be homogenous by local conservation authorities as reflected in land settlement agreements in co-managed parks. We argue that collaborative governance arrangements need to reflect and be understood within the broader background of complex local realities.
- Full Text: false
- Date Issued: 2015
- Authors: Thondhlana, Gladman , Shackleton, Sheona E , Blignaut, James
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67689 , vital:29130 , https://doi.org/10.1016/j.landusepol.2015.03.013
- Description: Publisher version , Crafting local institutions to allow more effective decision-making in the management of and access to natural resources in and beyond parks has long been considered key to collaborative governance. South Africa, in particular, has vigorously pursued collaborative governance as a desired approach to managing natural resources as evident in the new arrangements for previously restricted parks. However, though the discourse of collaborative governance has occupied conservation thinking and practice globally, few studies have looked at the interplay between local institutions, actors and collaborative governance involving indigenous hunter–gatherer communities in Southern Africa. In response, we assess the local actors and institutions that were put in place to facilitate collaborative governance of natural resources in the Kgalagadi Transfrontier Park and its surrounds in South Africa. Our findings show that though collaborative governance has a practical appeal, it is hampered by lack of participation in decision-making, information dissemination, transparency, trust and accountability, power relations, divergent interests and unequal access to natural resources. The findings also draw our attention to issues of heterogeneity, even within indigenous communities assumed to be homogenous by local conservation authorities as reflected in land settlement agreements in co-managed parks. We argue that collaborative governance arrangements need to reflect and be understood within the broader background of complex local realities.
- Full Text: false
- Date Issued: 2015
Phototransferred thermoluminescence of synthetic quartz: analysis of illumination-time response curves
- Chithambo, Makaiko L, Niyonzima, P, Kalita, Jitumani M
- Authors: Chithambo, Makaiko L , Niyonzima, P , Kalita, Jitumani M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/111020 , vital:33364 , https://doi.org/10.1016/j.jlumin.2018.02.029
- Description: Phototransferred thermoluminescence (PTTL) induced in synthetic quartz by 470 nm blue light is reported. The glow curve measured at 5 °C/s up to 500 °C after irradiation to 100 Gy shows six peaks at 94, 116, 175, 212, 280 and 348 °C labelled I through VI and another one at 80 °C (labelled A1). PTTL is only observed for peaks A1 and I and is induced at peak A1 as long as peak III has been removed by preheating and at peak I after preheating to deplete peak VI. The inducement of PTTL even when all peaks have been removed points to deep electron traps in the quartz also acting as donors in addition to the putative ones below 500 °C. The PTTL intensity as a function of duration of illumination for A1 goes through a peak and decreases monotonically or to a stable value depending on the preheating temperature. The change of PTTL intensity as a function of illumination time is described using a set of coupled linear differential equations. The number of acceptors and donors in a particular system described in this way is influenced by the preheating temperature.
- Full Text: false
- Date Issued: 2018
- Authors: Chithambo, Makaiko L , Niyonzima, P , Kalita, Jitumani M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/111020 , vital:33364 , https://doi.org/10.1016/j.jlumin.2018.02.029
- Description: Phototransferred thermoluminescence (PTTL) induced in synthetic quartz by 470 nm blue light is reported. The glow curve measured at 5 °C/s up to 500 °C after irradiation to 100 Gy shows six peaks at 94, 116, 175, 212, 280 and 348 °C labelled I through VI and another one at 80 °C (labelled A1). PTTL is only observed for peaks A1 and I and is induced at peak A1 as long as peak III has been removed by preheating and at peak I after preheating to deplete peak VI. The inducement of PTTL even when all peaks have been removed points to deep electron traps in the quartz also acting as donors in addition to the putative ones below 500 °C. The PTTL intensity as a function of duration of illumination for A1 goes through a peak and decreases monotonically or to a stable value depending on the preheating temperature. The change of PTTL intensity as a function of illumination time is described using a set of coupled linear differential equations. The number of acceptors and donors in a particular system described in this way is influenced by the preheating temperature.
- Full Text: false
- Date Issued: 2018
Preliminary evidence for the organisation of a bacterial community by zooplanktivores at the top of an estuarine planktonic food web
- Wasserman, Ryan J, Matcher, Gwynneth F, Vink, Tim J F, Froneman, P William
- Authors: Wasserman, Ryan J , Matcher, Gwynneth F , Vink, Tim J F , Froneman, P William
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68237 , vital:29222 , https://doi.org/10.1007/s00248-014-0505-3
- Description: Publisher version , As part of a larger investigation, the effect of apex predation on estuarine bacterial community structure, through trophic cascading, was investigated using experimental in situ mesocosms. Through either the removal (filtration) or addition of specific size classes of planktonic groups, four different trophic scenarios were established using estuarine water and its associated plankton. One such treatment represented a “natural” scenario in which stable apex predatory pressure was qualified. Water samples were collected over time from each of the treatments for bacterial community evaluation. These samples were assessed through pyrosequencing of the variable regions 4 and 5 of the bacterial 16S rRNA gene and analysed at the species operational taxonomic unit (OTU) level using a community procedure. The blue-green group dominated the samples, followed by Proteobacteria and Bacteroidetes. Samples were the most similar among treatments at the commencement of the experiment. While the bacterial communities sampled within each treatment changed over time, the deviation from initial appeared to be linked to the treatment trophic scenarios. The least temporal deviation-from-initial in bacterial community was found within the stable apex predatory pressure treatment. These findings are consistent with trophic cascade theory, whereby predators mediate interactions at multiple lower trophic levels with consequent repercussions for diversity.
- Full Text: false
- Date Issued: 2015
- Authors: Wasserman, Ryan J , Matcher, Gwynneth F , Vink, Tim J F , Froneman, P William
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68237 , vital:29222 , https://doi.org/10.1007/s00248-014-0505-3
- Description: Publisher version , As part of a larger investigation, the effect of apex predation on estuarine bacterial community structure, through trophic cascading, was investigated using experimental in situ mesocosms. Through either the removal (filtration) or addition of specific size classes of planktonic groups, four different trophic scenarios were established using estuarine water and its associated plankton. One such treatment represented a “natural” scenario in which stable apex predatory pressure was qualified. Water samples were collected over time from each of the treatments for bacterial community evaluation. These samples were assessed through pyrosequencing of the variable regions 4 and 5 of the bacterial 16S rRNA gene and analysed at the species operational taxonomic unit (OTU) level using a community procedure. The blue-green group dominated the samples, followed by Proteobacteria and Bacteroidetes. Samples were the most similar among treatments at the commencement of the experiment. While the bacterial communities sampled within each treatment changed over time, the deviation from initial appeared to be linked to the treatment trophic scenarios. The least temporal deviation-from-initial in bacterial community was found within the stable apex predatory pressure treatment. These findings are consistent with trophic cascade theory, whereby predators mediate interactions at multiple lower trophic levels with consequent repercussions for diversity.
- Full Text: false
- Date Issued: 2015
Section 40 of the Consumer Protection Act in comparative perspective: aantekeninge
- Authors: Glover, Graham B
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/70527 , vital:29672 , https://hdl.handle.net/10520/EJC144971
- Description: The purpose of this comment is to consider some of the problems with how we are to understand the role and purpose of section 40 of South Africa's Consumer Protection Act 68 of 2008 when viewed from a doctrinal perspective. Section 40 has the heading "Unconscionable conduct", and contains three subsections.
- Full Text: false
- Date Issued: 2013
- Authors: Glover, Graham B
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/70527 , vital:29672 , https://hdl.handle.net/10520/EJC144971
- Description: The purpose of this comment is to consider some of the problems with how we are to understand the role and purpose of section 40 of South Africa's Consumer Protection Act 68 of 2008 when viewed from a doctrinal perspective. Section 40 has the heading "Unconscionable conduct", and contains three subsections.
- Full Text: false
- Date Issued: 2013
Structural and optical properties of sol-gel derived α-Fe2O3 nanoparticles
- Mathevula, Langutani E, Noto, L L, Mothudi, Bakang M, Chithambo, Makaiko L, Dhlamini, M S
- Authors: Mathevula, Langutani E , Noto, L L , Mothudi, Bakang M , Chithambo, Makaiko L , Dhlamini, M S
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/115467 , vital:34145 , DOI: 10.1016/j.jlumin.2017.07.055
- Description: α-Fe2O3 nanoparticles of crystallite size between 3.9 and 9.5 nm were synthesized by a simple sol-gel method using iron (III) nitrate nonahydrate (Fe(NO3)3·9H2O) as a precursor. Polyvinyl alcohol (PVA) was added as a capping agent to avoid agglomeration of the nanoparticles. A single pure phase was obtained when the sample was annealed at 300 °C and 600 °C. The purity was further confirmed with the Fourier Transform Infrared Spectroscopy. The energy band gap of the materials was extrapolated from the Kubelka-Munk relation and it ranges between 1.8 and 2.3 eV. The Photoluminescence of the 3 samples shows a broad emission spectrum centered at about 422 nm when excited by a 336 nm lamp. The emission peaks intensities increased with an increase in the annealing temperature, accept for the 576 nm peak, which was quenched as the temperature increased from 300 °C to 600 °C. The thermoluminescence glow curves were carried out at different heating rates and the samples were exposed to different beta particle doses (82–1315 Gy). The activation energy of the trapped electrons was determined.
- Full Text: false
- Date Issued: 2017
- Authors: Mathevula, Langutani E , Noto, L L , Mothudi, Bakang M , Chithambo, Makaiko L , Dhlamini, M S
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/115467 , vital:34145 , DOI: 10.1016/j.jlumin.2017.07.055
- Description: α-Fe2O3 nanoparticles of crystallite size between 3.9 and 9.5 nm were synthesized by a simple sol-gel method using iron (III) nitrate nonahydrate (Fe(NO3)3·9H2O) as a precursor. Polyvinyl alcohol (PVA) was added as a capping agent to avoid agglomeration of the nanoparticles. A single pure phase was obtained when the sample was annealed at 300 °C and 600 °C. The purity was further confirmed with the Fourier Transform Infrared Spectroscopy. The energy band gap of the materials was extrapolated from the Kubelka-Munk relation and it ranges between 1.8 and 2.3 eV. The Photoluminescence of the 3 samples shows a broad emission spectrum centered at about 422 nm when excited by a 336 nm lamp. The emission peaks intensities increased with an increase in the annealing temperature, accept for the 576 nm peak, which was quenched as the temperature increased from 300 °C to 600 °C. The thermoluminescence glow curves were carried out at different heating rates and the samples were exposed to different beta particle doses (82–1315 Gy). The activation energy of the trapped electrons was determined.
- Full Text: false
- Date Issued: 2017
The elephant in the ‘room’: determinants of songbird assemblages in the Thicket Biome, South Africa
- Authors: Parker, Daniel M
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/105134 , vital:32468 , https://doi.org/10.1080/01584197.2018.1562847
- Description: When vegetation structure is altered, songbird communities may be affected. Despite speculation that African Elephant (Loxodonta africana) browsing impacts bird communities, existing data are limited. I sampled the bird communities of the Albany Thicket Biome at 10 sites in the Eastern Cape, South Africa, half with elephants and half without. Songbird community parameters were best predicted by how long elephants had been present, elephant density and the percentage cover of thicket vegetation. The sites where elephants had been present for longer had more bird species and increased songbird density and diversity. However, bird density also increased with increasing thicket vegetation cover and this is a phenomenon unlikely to be compatible with long-term elephant presence. There was an almost equal split between the number of bird species that appeared to be negatively affected by changes in habitat structure (47%) and those which benefited (53%). Smaller birds were generally more abundant as vegetation structural integrity increased and larger birds were more abundant when vegetation structural integrity declined. The browsing of elephants could be viewed as facilitative for songbirds in the short term. However, this effect may not persist in the long term because all elephant populations (notorious tree-fellers) in the Eastern Cape are found in fenced areas where natural migration is not possible. More broadly, my data provide important insight into how avian communities respond to habitat transformation at the local and regional scales.
- Full Text: false
- Date Issued: 2019
- Authors: Parker, Daniel M
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/105134 , vital:32468 , https://doi.org/10.1080/01584197.2018.1562847
- Description: When vegetation structure is altered, songbird communities may be affected. Despite speculation that African Elephant (Loxodonta africana) browsing impacts bird communities, existing data are limited. I sampled the bird communities of the Albany Thicket Biome at 10 sites in the Eastern Cape, South Africa, half with elephants and half without. Songbird community parameters were best predicted by how long elephants had been present, elephant density and the percentage cover of thicket vegetation. The sites where elephants had been present for longer had more bird species and increased songbird density and diversity. However, bird density also increased with increasing thicket vegetation cover and this is a phenomenon unlikely to be compatible with long-term elephant presence. There was an almost equal split between the number of bird species that appeared to be negatively affected by changes in habitat structure (47%) and those which benefited (53%). Smaller birds were generally more abundant as vegetation structural integrity increased and larger birds were more abundant when vegetation structural integrity declined. The browsing of elephants could be viewed as facilitative for songbirds in the short term. However, this effect may not persist in the long term because all elephant populations (notorious tree-fellers) in the Eastern Cape are found in fenced areas where natural migration is not possible. More broadly, my data provide important insight into how avian communities respond to habitat transformation at the local and regional scales.
- Full Text: false
- Date Issued: 2019
The influence of radiation-induced defects on thermoluminescence and optically stimulated luminescence of α-Al2O3: C
- Nyirenda, Angel N, Chithambo, Makaiko L
- Authors: Nyirenda, Angel N , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/119818 , vital:34786 , https://doi.org/10.1016/j.nimb.2017.02.077
- Description: It is known that when α-Al2O3:C is exposed to excessive amounts of ionising radiation, defects are induced within its matrix. We report the influence of radiation-induced defects on the thermoluminescence (TL) and optically stimulated luminescence (OSL) measured from α-Al2O3:C after irradiation to 1000 Gy. These radiation-induced defects are thermally unstable in the region 450–650 °C and result in TL peaks in this range when the TL is measured at 1 °C/s. Heating a sample to 700 °C obliterates the radiation-induced defects, that is, the TL peaks corresponding to the radiation induced defects are no longer observed in the subsequent TL measurements when moderate irradiation doses below 10 Gy are used. The charge traps associated with these radiation-induced defects are more stable than the dosimetric trap when the sample is exposed to either sunlight or 470-nm blue light from LEDs. TL glow curves measured following the defect-inducing irradiation produce a dosimetric peak that is broader and positioned at a higher temperature than observed in glow curves obtained before the heavy irradiation. In addition, sample sensitization/desensitization occurs due to the presence of these radiation-induced defects. Furthermore, both the activation energy and the kinetic order of the dosimetric peak evaluated when the radiation-induced defects are present in the sample are significantly lower in value than those obtained when these defects are absent. The radiation-induced defects also affect the shape and total light sum of the OSL signal as well as the position and width of the resultant residual phototransferred thermoluminescence main peak.
- Full Text: false
- Date Issued: 2017
- Authors: Nyirenda, Angel N , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/119818 , vital:34786 , https://doi.org/10.1016/j.nimb.2017.02.077
- Description: It is known that when α-Al2O3:C is exposed to excessive amounts of ionising radiation, defects are induced within its matrix. We report the influence of radiation-induced defects on the thermoluminescence (TL) and optically stimulated luminescence (OSL) measured from α-Al2O3:C after irradiation to 1000 Gy. These radiation-induced defects are thermally unstable in the region 450–650 °C and result in TL peaks in this range when the TL is measured at 1 °C/s. Heating a sample to 700 °C obliterates the radiation-induced defects, that is, the TL peaks corresponding to the radiation induced defects are no longer observed in the subsequent TL measurements when moderate irradiation doses below 10 Gy are used. The charge traps associated with these radiation-induced defects are more stable than the dosimetric trap when the sample is exposed to either sunlight or 470-nm blue light from LEDs. TL glow curves measured following the defect-inducing irradiation produce a dosimetric peak that is broader and positioned at a higher temperature than observed in glow curves obtained before the heavy irradiation. In addition, sample sensitization/desensitization occurs due to the presence of these radiation-induced defects. Furthermore, both the activation energy and the kinetic order of the dosimetric peak evaluated when the radiation-induced defects are present in the sample are significantly lower in value than those obtained when these defects are absent. The radiation-induced defects also affect the shape and total light sum of the OSL signal as well as the position and width of the resultant residual phototransferred thermoluminescence main peak.
- Full Text: false
- Date Issued: 2017
The inhibitory effects of various substrate pre-treatment by-products and wash liquors on mannanolytic enzymes
- Malgas, Samkelo, Van Dyk, J Susan, Abboo, Sagaran, Pletschke, Brett I
- Authors: Malgas, Samkelo , Van Dyk, J Susan , Abboo, Sagaran , Pletschke, Brett I
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66156 , vital:28911 , https://doi.org/10.1016/j.molcatb.2015.11.014
- Description: publisher version , Biomass pre-treatment is essential for achieving high levels of bioconversion through increased accessibility of hydrolytic enzymes to hydrolysable carbohydrates. However, pre-treatment by-products, such as sugar and lignin degradation products, can negatively affect the performance of hydrolytic (mannanolytic) enzymes. In this study, two monomeric sugars, five sugar degradation products, five lignin derivatives and four liquors from biomass feedstocks pre-treated by different technologies, were evaluated for their inhibitory effects on mannanolytic enzymes (α-galactosidases, β-mannanases and β-mannosidases). Lignin derivatives elicited the greatest inhibitory effect on the mannanolytic enzymes, followed by organic acids and furan derivatives derived from sugar degradation. Lignin derivative inhibition appeared to be as a result of protein–phenolic complexation, leading to protein precipitating out of solution. The functional groups on the phenolic lignin derivatives appeared to be directly related to the ability of the phenolic to interfere with enzyme activity, with the phenolic containing the highest hydroxyl group content exhibiting the greatest inhibition. It was also demonstrated that various pre-treatment technologies render different pre-treatment soluble by-products which interact in various ways with the mannanolytic enzymes. The different types of biomass (i.e. different plant species) were also shown to release different by-products that interacted with the mannanolytic enzymes in a diverse manner even when the biomass was pre-treated using the same technology. Enzyme inhibition by pre-treatment by-products can be alleviated through the removal of these compounds prior to enzymatic hydrolysis to maximize enzyme activity.
- Full Text: false
- Date Issued: 2016
- Authors: Malgas, Samkelo , Van Dyk, J Susan , Abboo, Sagaran , Pletschke, Brett I
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66156 , vital:28911 , https://doi.org/10.1016/j.molcatb.2015.11.014
- Description: publisher version , Biomass pre-treatment is essential for achieving high levels of bioconversion through increased accessibility of hydrolytic enzymes to hydrolysable carbohydrates. However, pre-treatment by-products, such as sugar and lignin degradation products, can negatively affect the performance of hydrolytic (mannanolytic) enzymes. In this study, two monomeric sugars, five sugar degradation products, five lignin derivatives and four liquors from biomass feedstocks pre-treated by different technologies, were evaluated for their inhibitory effects on mannanolytic enzymes (α-galactosidases, β-mannanases and β-mannosidases). Lignin derivatives elicited the greatest inhibitory effect on the mannanolytic enzymes, followed by organic acids and furan derivatives derived from sugar degradation. Lignin derivative inhibition appeared to be as a result of protein–phenolic complexation, leading to protein precipitating out of solution. The functional groups on the phenolic lignin derivatives appeared to be directly related to the ability of the phenolic to interfere with enzyme activity, with the phenolic containing the highest hydroxyl group content exhibiting the greatest inhibition. It was also demonstrated that various pre-treatment technologies render different pre-treatment soluble by-products which interact in various ways with the mannanolytic enzymes. The different types of biomass (i.e. different plant species) were also shown to release different by-products that interacted with the mannanolytic enzymes in a diverse manner even when the biomass was pre-treated using the same technology. Enzyme inhibition by pre-treatment by-products can be alleviated through the removal of these compounds prior to enzymatic hydrolysis to maximize enzyme activity.
- Full Text: false
- Date Issued: 2016
The myth of authenticity : folktales and nationalism in the 'new South Africa'
- Authors: Naidu, Samantha
- Date: 2001
- Language: English
- Type: Article , text
- Identifier: vital:26378 , http://hdl.handle.net/10962/54047 , https://orcid.org/0000-0001-9456-8657
- Description: Folktales texts are published in glorious, polychromatic, innovative forms that promote the texts as both culturally educational and entertaining.
- Full Text: false
- Date Issued: 2001
- Authors: Naidu, Samantha
- Date: 2001
- Language: English
- Type: Article , text
- Identifier: vital:26378 , http://hdl.handle.net/10962/54047 , https://orcid.org/0000-0001-9456-8657
- Description: Folktales texts are published in glorious, polychromatic, innovative forms that promote the texts as both culturally educational and entertaining.
- Full Text: false
- Date Issued: 2001
Vertebrate Biostratigraphy of the Witteberg Group and the Devonian-Carboniferous boundary in South Africa
- Authors: Gess, Robert W
- Date: 2016
- Language: English
- Type: text , boook chapter
- Identifier: http://hdl.handle.net/10962/73987 , vital:30248 , https://doi.org/10.1007/978-3-319-40859-0_13
- Description: Witteberg Group rocks are Late Devonian to Early Carboniferous in age. Comparison with Laurasian sea-level curves has correlated the earliest Carboniferous Tournasian transgression, with the argillaceous Kweekvlei Formation, overlying the arenaceous Witpoort Formation. The Devonian/Carboniferous boundary is globally characterised by a Mass Extinction which extinguished the entire grade of placoderm fish and radically reduced sarcopterygian and acanthodian diversity, preluding an Early Carboniferous radiation of actinopterygians. Analysis of Cape Supergroup biostratigraphy reveals that a fauna preservationally dominated by placoderms, sharks, and gyracanthid acanthodians may be traced from the Upper Bokkeveld Group through the Wagondrift Formation (Witteberg Group) to the Witpoort Formation, wherein it displays an increased diversity of placoderms, as well as sarcopterygians. Overlying strata contain no placoderms or sarcopterygians, but present are some relict sharks and acanthodians, and an increasing abundance of actinopterygians. This congruence confirms sea-level curve based age estimates of the Witteberg Group and the position of the Devonian/Carboniferous boundary.
- Full Text: false
- Date Issued: 2016
- Authors: Gess, Robert W
- Date: 2016
- Language: English
- Type: text , boook chapter
- Identifier: http://hdl.handle.net/10962/73987 , vital:30248 , https://doi.org/10.1007/978-3-319-40859-0_13
- Description: Witteberg Group rocks are Late Devonian to Early Carboniferous in age. Comparison with Laurasian sea-level curves has correlated the earliest Carboniferous Tournasian transgression, with the argillaceous Kweekvlei Formation, overlying the arenaceous Witpoort Formation. The Devonian/Carboniferous boundary is globally characterised by a Mass Extinction which extinguished the entire grade of placoderm fish and radically reduced sarcopterygian and acanthodian diversity, preluding an Early Carboniferous radiation of actinopterygians. Analysis of Cape Supergroup biostratigraphy reveals that a fauna preservationally dominated by placoderms, sharks, and gyracanthid acanthodians may be traced from the Upper Bokkeveld Group through the Wagondrift Formation (Witteberg Group) to the Witpoort Formation, wherein it displays an increased diversity of placoderms, as well as sarcopterygians. Overlying strata contain no placoderms or sarcopterygians, but present are some relict sharks and acanthodians, and an increasing abundance of actinopterygians. This congruence confirms sea-level curve based age estimates of the Witteberg Group and the position of the Devonian/Carboniferous boundary.
- Full Text: false
- Date Issued: 2016
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