Effect of the killing method on post-mortem change in length of larvae of Thanatophilus micans (Fabricius, 1794) (Coleoptera: Silphidae) stored in 70% ethanol
- Midgley, John M, Villet, Martin H
- Authors: Midgley, John M , Villet, Martin H
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6857 , http://hdl.handle.net/10962/d1011140
- Description: It is recommended that insect larvae collected for forensic purposes should be killed using the same method as was used to create existing models for rate of development. Certain killing methods have been shown to be preferable because they cause less distortion of the specimens, but these are not always practicable in a particular case, and so a method of correcting for effect of killing method is required. Larvae of all instars of Thanatophilus micans (Fabricius 1794) (Coleoptera: Silphidae) were measured and then killed by immersion in ethanol, immersion in hot water or freezing. Samples were re-measured immediately after death, then stored in excess 70% ethanol and re-measured after 1 week and again after 4 weeks. The change in length was significantly different from zero in all samples (t = -9.07022, p < 0.001). An analysis of covariance showed that instar, killing method and storage time all had a significant effect on the change in length. The results showed that T. micans larvae have a great potential for change in length during storage but that the change is not predictable, as the magnitude and sign of the change are variable.
- Full Text:
- Authors: Midgley, John M , Villet, Martin H
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6857 , http://hdl.handle.net/10962/d1011140
- Description: It is recommended that insect larvae collected for forensic purposes should be killed using the same method as was used to create existing models for rate of development. Certain killing methods have been shown to be preferable because they cause less distortion of the specimens, but these are not always practicable in a particular case, and so a method of correcting for effect of killing method is required. Larvae of all instars of Thanatophilus micans (Fabricius 1794) (Coleoptera: Silphidae) were measured and then killed by immersion in ethanol, immersion in hot water or freezing. Samples were re-measured immediately after death, then stored in excess 70% ethanol and re-measured after 1 week and again after 4 weeks. The change in length was significantly different from zero in all samples (t = -9.07022, p < 0.001). An analysis of covariance showed that instar, killing method and storage time all had a significant effect on the change in length. The results showed that T. micans larvae have a great potential for change in length during storage but that the change is not predictable, as the magnitude and sign of the change are variable.
- Full Text:
Effects of food quality on tissue-specific isotope ratios in the mussel Perna perna
- Hill, Jaclyn M, McQuaid, Christopher D
- Authors: Hill, Jaclyn M , McQuaid, Christopher D
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444563 , vital:74251 , https://doi.org/10.1007/s10750-009-9865-y
- Description: Investigations into trophic ecology and aquatic food web resolution are increasingly accomplished through stable isotope analysis. The incorporation of dietary and metabolic changes over time results in variations in isotope signatures and turnover rates of producers and consumers at tissue, individual, population and species levels. Consequently, the elucidation of trophic relationships in aquatic systems depends on establishing standard isotope values and tissue turnover rates for the level in question. This study investigated the effect of diet and food quality on isotopic signatures of four mussel tissues: adductor muscle, gonad, gill and mantle tissue from the brown mussel Perna perna. In the laboratory, mussels were fed one of the two isotopically distinct diets for 3 months.
- Full Text:
- Authors: Hill, Jaclyn M , McQuaid, Christopher D
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444563 , vital:74251 , https://doi.org/10.1007/s10750-009-9865-y
- Description: Investigations into trophic ecology and aquatic food web resolution are increasingly accomplished through stable isotope analysis. The incorporation of dietary and metabolic changes over time results in variations in isotope signatures and turnover rates of producers and consumers at tissue, individual, population and species levels. Consequently, the elucidation of trophic relationships in aquatic systems depends on establishing standard isotope values and tissue turnover rates for the level in question. This study investigated the effect of diet and food quality on isotopic signatures of four mussel tissues: adductor muscle, gonad, gill and mantle tissue from the brown mussel Perna perna. In the laboratory, mussels were fed one of the two isotopically distinct diets for 3 months.
- Full Text:
Effects of the number of ring substituents of cobalt carboxyphthalocyanines on the electrocatalytic detection of nitrite, cysteine and melatonin
- Matemadombo, Fungisai, Sehlotho, Nthapo, Nyokong, Tebello
- Authors: Matemadombo, Fungisai , Sehlotho, Nthapo , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263408 , vital:53625 , xlink:href="https://doi.org/10.1142/S108842460900125X"
- Description: Cobalt phthalocyanine (CoPc), cobalt tetracarboxy phthalocyanine (CoTCPc) and cobalt octacarboxy phthalocyanine (CoOCPc), adsorbed onto glassy carbon electrodes, have been used for the electrocatalytic detection of nitrite, L-cysteine and melatonin. The modified electrodes electrocatalytically detected nitrite around 800 mV vs.Ag|AgCl, a value less positive compared to that of an unmodified glassy carbon electrode (at 950 mV vs.Ag|AgCl) and also gave detection limits in the 10-7 M range for nitrite detection. L-cysteine was detected by the modified electrodes at potentials between 0.50 to 0.65 V vs.Ag|AgCl, with L-cysteine detection limits also in the 10-7 M range. The detection limits for melatonin ranged from 10-7 to 10-6 M. CoPc-modified electrodes displayed good separation of interferents (tryptophan and ascorbic acid) in the presence of melatonin. Analyses of commercial melatonin tablets using modified electrodes gave excellent agreement with manufacturer's value for all modified electrodes of this work.
- Full Text:
- Authors: Matemadombo, Fungisai , Sehlotho, Nthapo , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263408 , vital:53625 , xlink:href="https://doi.org/10.1142/S108842460900125X"
- Description: Cobalt phthalocyanine (CoPc), cobalt tetracarboxy phthalocyanine (CoTCPc) and cobalt octacarboxy phthalocyanine (CoOCPc), adsorbed onto glassy carbon electrodes, have been used for the electrocatalytic detection of nitrite, L-cysteine and melatonin. The modified electrodes electrocatalytically detected nitrite around 800 mV vs.Ag|AgCl, a value less positive compared to that of an unmodified glassy carbon electrode (at 950 mV vs.Ag|AgCl) and also gave detection limits in the 10-7 M range for nitrite detection. L-cysteine was detected by the modified electrodes at potentials between 0.50 to 0.65 V vs.Ag|AgCl, with L-cysteine detection limits also in the 10-7 M range. The detection limits for melatonin ranged from 10-7 to 10-6 M. CoPc-modified electrodes displayed good separation of interferents (tryptophan and ascorbic acid) in the presence of melatonin. Analyses of commercial melatonin tablets using modified electrodes gave excellent agreement with manufacturer's value for all modified electrodes of this work.
- Full Text:
Electrostatic self-assembly of quaternized 2,(3)-tetra (oxo-pyridine) phthalocyaninato chloroindium (III) with a series of tetrasulfonated phthalocyanines
- George, Reama C, Durmus, Mahmut, Egharevba, Gabriel O, Nyokong, Tebello
- Authors: George, Reama C , Durmus, Mahmut , Egharevba, Gabriel O , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263330 , vital:53618 , xlink:href="https://doi.org/10.1016/j.poly.2009.07.035"
- Description: The self-assembly of oppositely charged phthalocyanines, fabricated using quaternized 2,(3)-tetra(oxo-pyridine) phthalocyaninato chloroindium (III) (QInPyPc) as the positively charge molecule and a series of tetrasulfonate phthalocyanine (MTSPc), M = 2H, Mn, Fe, Co and Ni as negatively charged molecules are reported. The self-assembly results in the formation of heteroaggregates. The metallated sulfonated phthalocyanines form nanorod and nanoleaf shaped structures as evidenced by transmission electron microscopy (TEM). The UV–Vis spectra showed blue shifted Q bands, suggesting that these structures were in a face-to-face arrangement. The Raman spectra of the heteroaggregates showed shifting compared to the spectra of the precursors.
- Full Text:
- Authors: George, Reama C , Durmus, Mahmut , Egharevba, Gabriel O , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263330 , vital:53618 , xlink:href="https://doi.org/10.1016/j.poly.2009.07.035"
- Description: The self-assembly of oppositely charged phthalocyanines, fabricated using quaternized 2,(3)-tetra(oxo-pyridine) phthalocyaninato chloroindium (III) (QInPyPc) as the positively charge molecule and a series of tetrasulfonate phthalocyanine (MTSPc), M = 2H, Mn, Fe, Co and Ni as negatively charged molecules are reported. The self-assembly results in the formation of heteroaggregates. The metallated sulfonated phthalocyanines form nanorod and nanoleaf shaped structures as evidenced by transmission electron microscopy (TEM). The UV–Vis spectra showed blue shifted Q bands, suggesting that these structures were in a face-to-face arrangement. The Raman spectra of the heteroaggregates showed shifting compared to the spectra of the precursors.
- Full Text:
eServices provisioning in a community development context through a JADE MAS platform
- Thinyane, Mamello, Terzoli, Alfredo, Clayton, Peter G
- Authors: Thinyane, Mamello , Terzoli, Alfredo , Clayton, Peter G
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430836 , vital:72720 , 10.1109/ICTD.2009.5426697
- Description: A growing proliferation of ICT4D interventions has necessitated the ex-ploration of innovative solutions for the provisioning of eServices in ru-ral, marginalized communities. The challenges currently faced in these interventions include: situating the developed applications within the cultural and ethnographic context of the target communities, integrating greater levels of granularity and flexibility within the applications for in-creased context sensitivity, handling the intermittence and instability of supporting infrastructural services. These are the challenges that we address in the context of ICT4D intervention undertaken in a rural community in the Eastern Cape province of South Africa. We explore the design and implementation of a Multi-Agent System (MAS) for this community as a platform for provisioning of context-sensitive eServ-ices, and highlight some observations with regards to the applicability and adequacy of the solution.
- Full Text:
- Authors: Thinyane, Mamello , Terzoli, Alfredo , Clayton, Peter G
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430836 , vital:72720 , 10.1109/ICTD.2009.5426697
- Description: A growing proliferation of ICT4D interventions has necessitated the ex-ploration of innovative solutions for the provisioning of eServices in ru-ral, marginalized communities. The challenges currently faced in these interventions include: situating the developed applications within the cultural and ethnographic context of the target communities, integrating greater levels of granularity and flexibility within the applications for in-creased context sensitivity, handling the intermittence and instability of supporting infrastructural services. These are the challenges that we address in the context of ICT4D intervention undertaken in a rural community in the Eastern Cape province of South Africa. We explore the design and implementation of a Multi-Agent System (MAS) for this community as a platform for provisioning of context-sensitive eServ-ices, and highlight some observations with regards to the applicability and adequacy of the solution.
- Full Text:
Establishment of translocated populations of smallmouth yellowfish, Labeobarbus aeneus (Pisces: Cyprinidae), in lentic and lotic habitats in the Great Fish River system, South Africa
- Weyl, Olaf L F, Stadtlander, Timo, Booth, Anthony J
- Authors: Weyl, Olaf L F , Stadtlander, Timo , Booth, Anthony J
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124418 , vital:35607 , https://doi.org/10.3377/004.044.0109
- Description: As a result of numerous introductions and translocations of fishes, South Africa has recently been identified as a fish invasion hotspot (Leprieur et al. 2008). In freshwater ecosystems invasion by alien species is considered a leading mechanism driving environmental change (Clavero & Garcia- Berthou 2005; Garcia-Berthou et al. 2005). In South Africa, documented effects of fish invasions include the extirpation of indigenous fishes through predation (Cambray 2003), changes in invertebrate community structure (Lowe et al. 2008) and hybridization (Canonico et al. 2005). As a result, the management of alien species is a high national priority (National Environmental Management: Biodiversity Act 2004). Such management requires an understanding of the biology, ecology and establishment success of fishes outside their native range.
- Full Text:
- Authors: Weyl, Olaf L F , Stadtlander, Timo , Booth, Anthony J
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124418 , vital:35607 , https://doi.org/10.3377/004.044.0109
- Description: As a result of numerous introductions and translocations of fishes, South Africa has recently been identified as a fish invasion hotspot (Leprieur et al. 2008). In freshwater ecosystems invasion by alien species is considered a leading mechanism driving environmental change (Clavero & Garcia- Berthou 2005; Garcia-Berthou et al. 2005). In South Africa, documented effects of fish invasions include the extirpation of indigenous fishes through predation (Cambray 2003), changes in invertebrate community structure (Lowe et al. 2008) and hybridization (Canonico et al. 2005). As a result, the management of alien species is a high national priority (National Environmental Management: Biodiversity Act 2004). Such management requires an understanding of the biology, ecology and establishment success of fishes outside their native range.
- Full Text:
Evaluating text preprocessing to improve compression on maillogs
- Otten, Fred, Irwin, Barry V W, Thinyane, Hannah
- Authors: Otten, Fred , Irwin, Barry V W , Thinyane, Hannah
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430138 , vital:72668 , https://doi.org/10.1145/1632149.1632157
- Description: Maillogs contain important information about mail which has been sent or received. This information can be used for statistical purposes, to help prevent viruses or to help prevent SPAM. In order to satisfy regula-tions and follow good security practices, maillogs need to be monitored and archived. Since there is a large quantity of data, some form of data reduction is necessary. Data compression programs such as gzip and bzip2 are commonly used to reduce the quantity of data. Text preprocessing can be used to aid the compression of English text files. This paper evaluates whether text preprocessing, particularly word replacement, can be used to improve the compression of maillogs. It presents an algorithm for constructing a dictionary for word replacement and provides the results of experiments conducted using the ppmd, gzip, bzip2 and 7zip programs. These tests show that text prepro-cessing improves data compression on maillogs. Improvements of up to 56 percent in compression time and up to 32 percent in compression ratio are achieved. It also shows that a dictionary may be generated and used on other maillogs to yield reductions within half a percent of the results achieved for the maillog used to generate the dictionary.
- Full Text:
- Authors: Otten, Fred , Irwin, Barry V W , Thinyane, Hannah
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430138 , vital:72668 , https://doi.org/10.1145/1632149.1632157
- Description: Maillogs contain important information about mail which has been sent or received. This information can be used for statistical purposes, to help prevent viruses or to help prevent SPAM. In order to satisfy regula-tions and follow good security practices, maillogs need to be monitored and archived. Since there is a large quantity of data, some form of data reduction is necessary. Data compression programs such as gzip and bzip2 are commonly used to reduce the quantity of data. Text preprocessing can be used to aid the compression of English text files. This paper evaluates whether text preprocessing, particularly word replacement, can be used to improve the compression of maillogs. It presents an algorithm for constructing a dictionary for word replacement and provides the results of experiments conducted using the ppmd, gzip, bzip2 and 7zip programs. These tests show that text prepro-cessing improves data compression on maillogs. Improvements of up to 56 percent in compression time and up to 32 percent in compression ratio are achieved. It also shows that a dictionary may be generated and used on other maillogs to yield reductions within half a percent of the results achieved for the maillog used to generate the dictionary.
- Full Text:
Evaluating the IRI topside model for the South African region: An overview of the modelling techniques
- Sibanda, Patrick, McKinnell, Lee-Anne
- Authors: Sibanda, Patrick , McKinnell, Lee-Anne
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6810 , http://hdl.handle.net/10962/d1004303
- Description: The representation of the topside ionosphere (the region above the F2 peak) is critical because of the limited experimental data available. Over the years, a wide range of models have been developed in an effort to represent the behaviour and the shape of the electron density (Ne) profile of the topside ionosphere. Various studies have been centred around calculating the vertical scale height (VSH) and have included (a) obtaining VSH from Global Positioning System (GPS) derived total electron content (TEC), (b) calculating the VSH from ground-based ionosonde measurements, (c) using topside sounder vertical Ne profiles to obtain the VSH. One or a combination of the topside profilers (Chapman function, exponential function, sech-squared (Epstein) function, and/or parabolic function) is then used to reconstruct the topside Ne profile. The different approaches and the modelling techniques are discussed with a view to identifying the most adequate approach to apply to the South African region’s topside modelling efforts. The IRI-2001 topside model is evaluated based on how well it reproduces measured topside profiles over the South African region. This study is a first step in the process of developing a South African topside ionosphere model.
- Full Text:
- Authors: Sibanda, Patrick , McKinnell, Lee-Anne
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6810 , http://hdl.handle.net/10962/d1004303
- Description: The representation of the topside ionosphere (the region above the F2 peak) is critical because of the limited experimental data available. Over the years, a wide range of models have been developed in an effort to represent the behaviour and the shape of the electron density (Ne) profile of the topside ionosphere. Various studies have been centred around calculating the vertical scale height (VSH) and have included (a) obtaining VSH from Global Positioning System (GPS) derived total electron content (TEC), (b) calculating the VSH from ground-based ionosonde measurements, (c) using topside sounder vertical Ne profiles to obtain the VSH. One or a combination of the topside profilers (Chapman function, exponential function, sech-squared (Epstein) function, and/or parabolic function) is then used to reconstruct the topside Ne profile. The different approaches and the modelling techniques are discussed with a view to identifying the most adequate approach to apply to the South African region’s topside modelling efforts. The IRI-2001 topside model is evaluated based on how well it reproduces measured topside profiles over the South African region. This study is a first step in the process of developing a South African topside ionosphere model.
- Full Text:
Exploratory mathematics talk in a second language: a sociolinguistic perspective:
- Graven, Mellony, Robertson, Sally-Ann
- Authors: Graven, Mellony , Robertson, Sally-Ann
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69907 , vital:29594 , https://doi.org/10.1007/s11858-018-0952-2
- Description: This paper illuminates challenges confronting teachers and students at the literacy/numeracy interface in contexts where students have not developed sufficient English language proficiency to be learning mathematics through English but, due to socio-politically and economically driven perceptions are being taught in English. We analyse transcript data of classroom talk in a South African grade 4 mathematics lesson on fractions. Together with interview data, the lesson data highlight some of the consequences students’ diminished access to their home language appear to have on their access to mathematical meaning-making.
- Full Text:
- Authors: Graven, Mellony , Robertson, Sally-Ann
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69907 , vital:29594 , https://doi.org/10.1007/s11858-018-0952-2
- Description: This paper illuminates challenges confronting teachers and students at the literacy/numeracy interface in contexts where students have not developed sufficient English language proficiency to be learning mathematics through English but, due to socio-politically and economically driven perceptions are being taught in English. We analyse transcript data of classroom talk in a South African grade 4 mathematics lesson on fractions. Together with interview data, the lesson data highlight some of the consequences students’ diminished access to their home language appear to have on their access to mathematical meaning-making.
- Full Text:
Exploring job search and the causes of endogenous unemployment: evidence from Duncan Village, South Africa
- Authors: Duff, Patrick Alexander
- Date: 2009
- Subjects: Unemployment , Unemployment -- Social aspects -- South Africa -- East London -- Duncan Village , Job hunting -- South Africa -- East London -- Duncan Village , Labor market -- South Africa
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: vital:1026
- Description: Despite high rates of unemployment in South Africa, there is little consensus about its origins and solutions to the problem. Job search (how and when people search for work)is one aspect of the unemployment problem. Job search is shown to be a complex process strongly linked to the endogenous structure of the labour market. The flaws in traditional methods (theoretical and measurement) highlight this. Using data from a tailor-made survey in Duncan Village (a peri-urban area in Buffalo City, South Africa) the research examines factors that influence the effectiveness of job search. The results show that mode of search (how people look for work) is used as a signal by employers. Degrees of success are stratified amongst searchers using either ‘word of mouth’, place-to-place or formal modes of search. The thesis provides a method-test to reveal a complex body of evidence that has yet to be fully explored by practitioners in this field.
- Full Text:
- Authors: Duff, Patrick Alexander
- Date: 2009
- Subjects: Unemployment , Unemployment -- Social aspects -- South Africa -- East London -- Duncan Village , Job hunting -- South Africa -- East London -- Duncan Village , Labor market -- South Africa
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: vital:1026
- Description: Despite high rates of unemployment in South Africa, there is little consensus about its origins and solutions to the problem. Job search (how and when people search for work)is one aspect of the unemployment problem. Job search is shown to be a complex process strongly linked to the endogenous structure of the labour market. The flaws in traditional methods (theoretical and measurement) highlight this. Using data from a tailor-made survey in Duncan Village (a peri-urban area in Buffalo City, South Africa) the research examines factors that influence the effectiveness of job search. The results show that mode of search (how people look for work) is used as a signal by employers. Degrees of success are stratified amongst searchers using either ‘word of mouth’, place-to-place or formal modes of search. The thesis provides a method-test to reveal a complex body of evidence that has yet to be fully explored by practitioners in this field.
- Full Text:
Exploring Learner Participation in Waste-Management Activities in a Rural Botswana Primary School
- Authors: Silo, Nthalivi
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/386509 , vital:68148 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122820"
- Description: In Botswana, participation in environmental learning activities has been perceived as a central component of environmental education in formal education. Driven by the need to implement the objective of making the participatory approach part of the infusion of environmental education in the school curriculum as prescribed by the infusion policy, Botswana schools have come up with initiatives to involve learners in environmental education activities that seem to have ‘a direct, perceived benefit to the learners’ (NEESAP, 2007:9). Within this approach it is expected that learners should participate in these activities. However, Ketlhoilwe (2007) revealed that there has been a normalisation of environmental education into existing school culture through equating waste-management activities with environmental education. This generally entails cleaning activities by learners to maintain ‘clean schools’, which is directly associated with environmental education. Drawing from detailed case study data in one rural primary school with Standard 6 learners, I used Cultural Historical Activity Theory to investigate and explain how learners participate in these waste-management activities. Findings from this study revealed that attempts by teachers to meet the policy imperative through prescription of rules, and ascribing roles to learners in waste-management activities, create tensions. This gave rise to an elusive object of learner participation, as the purpose for their participation in these activities is not clear.
- Full Text:
- Authors: Silo, Nthalivi
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/386509 , vital:68148 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122820"
- Description: In Botswana, participation in environmental learning activities has been perceived as a central component of environmental education in formal education. Driven by the need to implement the objective of making the participatory approach part of the infusion of environmental education in the school curriculum as prescribed by the infusion policy, Botswana schools have come up with initiatives to involve learners in environmental education activities that seem to have ‘a direct, perceived benefit to the learners’ (NEESAP, 2007:9). Within this approach it is expected that learners should participate in these activities. However, Ketlhoilwe (2007) revealed that there has been a normalisation of environmental education into existing school culture through equating waste-management activities with environmental education. This generally entails cleaning activities by learners to maintain ‘clean schools’, which is directly associated with environmental education. Drawing from detailed case study data in one rural primary school with Standard 6 learners, I used Cultural Historical Activity Theory to investigate and explain how learners participate in these waste-management activities. Findings from this study revealed that attempts by teachers to meet the policy imperative through prescription of rules, and ascribing roles to learners in waste-management activities, create tensions. This gave rise to an elusive object of learner participation, as the purpose for their participation in these activities is not clear.
- Full Text:
Extending the NFComms: framework for bulk data transfers
- Nottingham, Alastair, Irwin, Barry V W
- Authors: Nottingham, Alastair , Irwin, Barry V W
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430164 , vital:72670 , https://doi.org/10.1145/1632149.1632170
- Description: Packet analysis is an important aspect of network security, which typi-cally relies on a flexible packet filtering system to extrapolate important packet information from each processed packet. Packet analysis is a computationally intensive, highly parallelisable task, and as such, clas-sification of large packet sets, such as those collected by a network tel-escope, can require significant processing time. We wish to improve upon this, through parallel classification on a GPU. In this paper, we first consider the OpenCL architecture and its applicability to packet analy-sis. We then introduce a number of packet demultiplexing and routing algorithms, and finally present a discussion on how some of these techniques may be leveraged within a GPGPU context to improve packet classification speeds.
- Full Text:
- Authors: Nottingham, Alastair , Irwin, Barry V W
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430164 , vital:72670 , https://doi.org/10.1145/1632149.1632170
- Description: Packet analysis is an important aspect of network security, which typi-cally relies on a flexible packet filtering system to extrapolate important packet information from each processed packet. Packet analysis is a computationally intensive, highly parallelisable task, and as such, clas-sification of large packet sets, such as those collected by a network tel-escope, can require significant processing time. We wish to improve upon this, through parallel classification on a GPU. In this paper, we first consider the OpenCL architecture and its applicability to packet analy-sis. We then introduce a number of packet demultiplexing and routing algorithms, and finally present a discussion on how some of these techniques may be leveraged within a GPGPU context to improve packet classification speeds.
- Full Text:
Fanon’s Curse: re-imagining Marxism in South Africa’s age of retreat
- Helliker, Kirk D, Vale, Peter C J
- Authors: Helliker, Kirk D , Vale, Peter C J
- Date: 2009
- Language: English
- Type: conference paper , text
- Identifier: http://hdl.handle.net/10962/61029 , vital:27924 , http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.587.740&rep=rep1&type=pdf
- Description: Given its growing, even dark, reputation for xenophobia, it seems extraordinary that South Africa remains open to ideas from the outside. Fifteen years after apartheid in South Africa ended, the country’s great cities are branded with the same imported images that clutter glittering malls in New York, London or Sydney. The rapidity of this makeover from apartheid’s grey conformity is held to be testimony to the success of neo-liberal globalisation which was enthusiastically embraced with apartheid’s ending.
- Full Text:
- Authors: Helliker, Kirk D , Vale, Peter C J
- Date: 2009
- Language: English
- Type: conference paper , text
- Identifier: http://hdl.handle.net/10962/61029 , vital:27924 , http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.587.740&rep=rep1&type=pdf
- Description: Given its growing, even dark, reputation for xenophobia, it seems extraordinary that South Africa remains open to ideas from the outside. Fifteen years after apartheid in South Africa ended, the country’s great cities are branded with the same imported images that clutter glittering malls in New York, London or Sydney. The rapidity of this makeover from apartheid’s grey conformity is held to be testimony to the success of neo-liberal globalisation which was enthusiastically embraced with apartheid’s ending.
- Full Text:
Film Review: Hollywood on Safari
- Authors: Amner, Roderick J
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142680 , vital:38101 , https://doi.org/10.1386/jams.1.2.335_4
- Description: Film Review: Hollywood on Safari.
- Full Text:
- Authors: Amner, Roderick J
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142680 , vital:38101 , https://doi.org/10.1386/jams.1.2.335_4
- Description: Film Review: Hollywood on Safari.
- Full Text:
Flies in the ointment a morphological and molecular comparison of Lucilia cuprina and Lucilia sericata (Diptera: Calliphoridae) in South Africa
- Tourle, Robyn, Downie, Douglas A, Villet, Martin H
- Authors: Tourle, Robyn , Downie, Douglas A , Villet, Martin H
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442156 , vital:73963 , https://doi.org/10.1111/j.1365-2915.2008.00765.x
- Description: Complementary nuclear (28S rRNA) and mitochondrial (COI) genes were sequenced from blowflies that phenotypically resembled Lucilia cuprina (W.), Lucilia sericata (Meigen) or exhibited characters of both species. The aim was to test a long‐held hypothesis that these species hybridize under natural conditions in South Africa (Ullyett, 1945). Blowflies were obtained predominantly from the Cape Town metropolitan area, but reference samples were acquired for L. sericata from Pretoria. Several L. cuprina‐like flies were shown to possess a conflicting combination of nuclear and mitochondrial genes that has also been seen in Hawaiian specimens. Homoplasy, sampling of pseudogenes, hybridization and incomplete lineage sorting are discussed as possible hypotheses for the pattern and the latter is concluded to represent the most likely explanation.
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- Authors: Tourle, Robyn , Downie, Douglas A , Villet, Martin H
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442156 , vital:73963 , https://doi.org/10.1111/j.1365-2915.2008.00765.x
- Description: Complementary nuclear (28S rRNA) and mitochondrial (COI) genes were sequenced from blowflies that phenotypically resembled Lucilia cuprina (W.), Lucilia sericata (Meigen) or exhibited characters of both species. The aim was to test a long‐held hypothesis that these species hybridize under natural conditions in South Africa (Ullyett, 1945). Blowflies were obtained predominantly from the Cape Town metropolitan area, but reference samples were acquired for L. sericata from Pretoria. Several L. cuprina‐like flies were shown to possess a conflicting combination of nuclear and mitochondrial genes that has also been seen in Hawaiian specimens. Homoplasy, sampling of pseudogenes, hybridization and incomplete lineage sorting are discussed as possible hypotheses for the pattern and the latter is concluded to represent the most likely explanation.
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Foreign policy ambiguity on the part of an emergent middle power: South African foreign policy through other lenses
- Serrão, Olivier, Bischoff, Paul, 1954-
- Authors: Serrão, Olivier , Bischoff, Paul, 1954-
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/161464 , vital:40629 , DOI: 10.1080/02589341003600189
- Description: This paper attempts to address the ambiguity so frequently highlighted in South Africa's post-apartheid foreign policy. Three central arguments are put forward. Firstly, it is argued that traditional accounts of South Africa's foreign policy, utilizing rationalist or ‘mainstream’ theories of International Relations, are insufficient in themselves to explain the complexities inherent in the country's foreign policy. In this regard, constructivist IR theory offers several key insights into studies of South Africa's foreign policy. Secondly, although it is argued that constructivism, particularly its focus on identity, is crucial to understanding South African foreign policy, it alone cannot sufficiently explain its reception or results on the world stage. Finally, it is argued that in order to fully appreciate both the nature and effects of South Africa's foreign policy, a mixed focus, incorporating insights from both constructivist and materialist-based theories of IR, is necessary.
- Full Text:
- Authors: Serrão, Olivier , Bischoff, Paul, 1954-
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/161464 , vital:40629 , DOI: 10.1080/02589341003600189
- Description: This paper attempts to address the ambiguity so frequently highlighted in South Africa's post-apartheid foreign policy. Three central arguments are put forward. Firstly, it is argued that traditional accounts of South Africa's foreign policy, utilizing rationalist or ‘mainstream’ theories of International Relations, are insufficient in themselves to explain the complexities inherent in the country's foreign policy. In this regard, constructivist IR theory offers several key insights into studies of South Africa's foreign policy. Secondly, although it is argued that constructivism, particularly its focus on identity, is crucial to understanding South African foreign policy, it alone cannot sufficiently explain its reception or results on the world stage. Finally, it is argued that in order to fully appreciate both the nature and effects of South Africa's foreign policy, a mixed focus, incorporating insights from both constructivist and materialist-based theories of IR, is necessary.
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Glumlazi
- Authors: Krueger, Anton
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229829 , vital:49715 , xlink:href="https://hdl.handle.net/10520/EJC47808"
- Full Text:
- Authors: Krueger, Anton
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229829 , vital:49715 , xlink:href="https://hdl.handle.net/10520/EJC47808"
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gpf: A GPU accelerated packet classification tool
- Nottingham, Alastair, Irwin, Barry V W
- Authors: Nottingham, Alastair , Irwin, Barry V W
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428103 , vital:72486 , https://d1wqtxts1xzle7.cloudfront.net/67098560/gPF_A_GPU_Accelerated_Packet_Classificat20210505-17707-zqqa4s.pdf?1620201469=andresponse-content-disposi-tion=inline%3B+filename%3DgPF_A_GPU_Accelerated_Packet_Classificat.pdfandExpires=1714733902andSignature=NQ~1DjH1XOuqF8u1Yq74XyG7kp~y0II81vu40SuWO2GQhSgToTHC7ynbAoP3MGv9do~bX1PCAp2Z2TCKUVHT7CmYNRxDmnpk5G4kefH--0VotMHVtFnHnf5Q9nhrp0MIgSxEhncOrlRx5K5sRhlLkyfDib3RS8Y8vu~FIPvm1DaZrfqCZSpXKmHh9r1etybRBRtUokzayPtgbhE41bQtW9wI8J4-JTQ9doyNC-JflFuEfUnhv5Phf45lr7TALm8G8nGZBp3z9-nSLZDxls2mvvVIANCdutyOMDnMDadGoqjIB2wYwUy~Fm424ZWj7fF89Ytj9xqIU63H4NFE2HodtQ__andKey-Pair-Id=APKAJLOHF5GGSLRBV4ZA
- Description: This paper outlines the design of gPF, a fast packet classifier optimised for parallel execution on current generation commodity graphics hard-ware. Specifically, gPF leverages the potential for both the parallel classi-fication of packets at runtime, and the use of evolutionary mechanisms, in the form of a GP-GPU genetic algorithm to produce contextually opti-mised filter permutations in order to reduce redundancy and improve the per-packet throughput rate of the resultant filter program. This paper demonstrates that these optimisations have significant potential for im-proving packet classification speeds, particularly with regard to bulk pack-et processing and saturated network environments.
- Full Text:
- Authors: Nottingham, Alastair , Irwin, Barry V W
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428103 , vital:72486 , https://d1wqtxts1xzle7.cloudfront.net/67098560/gPF_A_GPU_Accelerated_Packet_Classificat20210505-17707-zqqa4s.pdf?1620201469=andresponse-content-disposi-tion=inline%3B+filename%3DgPF_A_GPU_Accelerated_Packet_Classificat.pdfandExpires=1714733902andSignature=NQ~1DjH1XOuqF8u1Yq74XyG7kp~y0II81vu40SuWO2GQhSgToTHC7ynbAoP3MGv9do~bX1PCAp2Z2TCKUVHT7CmYNRxDmnpk5G4kefH--0VotMHVtFnHnf5Q9nhrp0MIgSxEhncOrlRx5K5sRhlLkyfDib3RS8Y8vu~FIPvm1DaZrfqCZSpXKmHh9r1etybRBRtUokzayPtgbhE41bQtW9wI8J4-JTQ9doyNC-JflFuEfUnhv5Phf45lr7TALm8G8nGZBp3z9-nSLZDxls2mvvVIANCdutyOMDnMDadGoqjIB2wYwUy~Fm424ZWj7fF89Ytj9xqIU63H4NFE2HodtQ__andKey-Pair-Id=APKAJLOHF5GGSLRBV4ZA
- Description: This paper outlines the design of gPF, a fast packet classifier optimised for parallel execution on current generation commodity graphics hard-ware. Specifically, gPF leverages the potential for both the parallel classi-fication of packets at runtime, and the use of evolutionary mechanisms, in the form of a GP-GPU genetic algorithm to produce contextually opti-mised filter permutations in order to reduce redundancy and improve the per-packet throughput rate of the resultant filter program. This paper demonstrates that these optimisations have significant potential for im-proving packet classification speeds, particularly with regard to bulk pack-et processing and saturated network environments.
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Grade-appropriate literacy and South African grade seven learners' classroom writing in English
- Authors: Hendricks, Monica
- Date: 2009
- Language: English
- Type: text , article
- Identifier: vital:7019 , http://hdl.handle.net/10962/d1007173 , https://doi.org/10.1080/03004430600989593
- Description: preprint , This paper reports on the writing of grade 7 learners in English as an additional language at four differently-resourced schools in the Eastern Cape Province, South Africa. Because grade 7 is the start of the senior phase of schooling, it is vital that learners achieve grade-level competence in the language used as medium of instruction. Learning outcome five which states that ‘the learner will be able to use language to think and reason, as well as access, process and use information for learning’ (Department of Education 2002) is particularly relevant. The primary research question asked what the writing practices in grade 7 additional languages were, and how these contribute to the development of learners’ writing. The findings were that literacy practices at all four schools privilege grammar exercises and personal, expressive writing. In terms of Cummins’s (1984) constructs of BICS (Basic Interpersonal Communicative Skill) and CALP (Cognitive Academic Language Proficiency), learners’ written competencies are mainly conversational (BICS). The personal expressive texts which predominate in learners’ writing have done little to develop a formal, impersonal academic register (CALP). Learners need to become familiar with the more abstract impersonal factual genres associated with disciplinary-based knowledge.
- Full Text:
- Authors: Hendricks, Monica
- Date: 2009
- Language: English
- Type: text , article
- Identifier: vital:7019 , http://hdl.handle.net/10962/d1007173 , https://doi.org/10.1080/03004430600989593
- Description: preprint , This paper reports on the writing of grade 7 learners in English as an additional language at four differently-resourced schools in the Eastern Cape Province, South Africa. Because grade 7 is the start of the senior phase of schooling, it is vital that learners achieve grade-level competence in the language used as medium of instruction. Learning outcome five which states that ‘the learner will be able to use language to think and reason, as well as access, process and use information for learning’ (Department of Education 2002) is particularly relevant. The primary research question asked what the writing practices in grade 7 additional languages were, and how these contribute to the development of learners’ writing. The findings were that literacy practices at all four schools privilege grammar exercises and personal, expressive writing. In terms of Cummins’s (1984) constructs of BICS (Basic Interpersonal Communicative Skill) and CALP (Cognitive Academic Language Proficiency), learners’ written competencies are mainly conversational (BICS). The personal expressive texts which predominate in learners’ writing have done little to develop a formal, impersonal academic register (CALP). Learners need to become familiar with the more abstract impersonal factual genres associated with disciplinary-based knowledge.
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Growing of trees in home-gardens by rural households in the Eastern Cape and Limpopo Provinces, South Africa:
- Shackleton, Charlie M, Paumgarten, Fiona, Cocks, Michelle L
- Authors: Shackleton, Charlie M , Paumgarten, Fiona , Cocks, Michelle L
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141360 , vital:37965 , DOI: 10.1080/13504500509469647
- Description: Trees provide a wide range of goods and services to rural households which, when incorporated into their livelihood strategies, help reduce their vulnerability to adversity. Governments and policy makers often ignore the contribution made by trees and consequently resources are focussed on cash crops and livestock. Villagers in the Eastern Cape and Limpopo Province, South Africa utilise a range of trees from home-gardens for various purposes, although predominantly for fruit and shade. Trees are either planted or actively retained in households' home-gardens. There were noticeable differences between the villages in the Eastern Cape and those in Limpopo Province, particularly with respect to the overall density of trees per hectare and the number of species per household, both being significantly greater in Limpopo Province. The five most preferred species were listed for each village, revealing a preference for exotic fruit trees in Limpopo Province and a mix of exotic fruit trees and shade trees in the Eastern Cape. Households also retained useful indigenous species, predominantly fruit-bearing species. A range of factors constrain tree growing in home-gardens and households engage in practices to grow and maintain their trees. Not all of these constraints and practices were significantly different between the various localities.
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- Authors: Shackleton, Charlie M , Paumgarten, Fiona , Cocks, Michelle L
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141360 , vital:37965 , DOI: 10.1080/13504500509469647
- Description: Trees provide a wide range of goods and services to rural households which, when incorporated into their livelihood strategies, help reduce their vulnerability to adversity. Governments and policy makers often ignore the contribution made by trees and consequently resources are focussed on cash crops and livestock. Villagers in the Eastern Cape and Limpopo Province, South Africa utilise a range of trees from home-gardens for various purposes, although predominantly for fruit and shade. Trees are either planted or actively retained in households' home-gardens. There were noticeable differences between the villages in the Eastern Cape and those in Limpopo Province, particularly with respect to the overall density of trees per hectare and the number of species per household, both being significantly greater in Limpopo Province. The five most preferred species were listed for each village, revealing a preference for exotic fruit trees in Limpopo Province and a mix of exotic fruit trees and shade trees in the Eastern Cape. Households also retained useful indigenous species, predominantly fruit-bearing species. A range of factors constrain tree growing in home-gardens and households engage in practices to grow and maintain their trees. Not all of these constraints and practices were significantly different between the various localities.
- Full Text: