'Alternative foods' and community-based development : Rooibos tea production in South Africa's West Coast mountains
- Nel, Etienne L, Binns, Tony, Bek, David
- Authors: Nel, Etienne L , Binns, Tony , Bek, David
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6718 , http://hdl.handle.net/10962/d1006791
- Description: Rooibos tee (red bush tea) (Aspalathus linearis, Fabaceae), which is indigenous only to the Cedarberg and neighbouring mountains of South Africa, has become popular internationally as a result of its apparent health-giving properties. Situated within the broader contexts of alternative food networks, alternate economic spaces and local/community-based development, this paper examines how two marginalised communities have successfully penetrated international markets by supplying organically produced rooibos tea which is certified by the international Fairtrade system. Focusing on the cases of Wupperthal and Heiveld, the paper explores the dynamics of the production and marketing process and the key variables involved. Success has been achieved through active NGO support, which has engaged with local skills and social capital, and has led to significant social and economic upliftment among the participating communities. The experience illustrates how, given the right conditions, poor communities in the South might participate successfully in global alternative food networks.
- Full Text:
- Date Issued: 2007
- Authors: Nel, Etienne L , Binns, Tony , Bek, David
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6718 , http://hdl.handle.net/10962/d1006791
- Description: Rooibos tee (red bush tea) (Aspalathus linearis, Fabaceae), which is indigenous only to the Cedarberg and neighbouring mountains of South Africa, has become popular internationally as a result of its apparent health-giving properties. Situated within the broader contexts of alternative food networks, alternate economic spaces and local/community-based development, this paper examines how two marginalised communities have successfully penetrated international markets by supplying organically produced rooibos tea which is certified by the international Fairtrade system. Focusing on the cases of Wupperthal and Heiveld, the paper explores the dynamics of the production and marketing process and the key variables involved. Success has been achieved through active NGO support, which has engaged with local skills and social capital, and has led to significant social and economic upliftment among the participating communities. The experience illustrates how, given the right conditions, poor communities in the South might participate successfully in global alternative food networks.
- Full Text:
- Date Issued: 2007
A few points on Pointfree pseudocompactness
- Authors: Dube, T , Matutu, Phethiwe P
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6783 , http://hdl.handle.net/10962/d1006926
- Description: We present several characterizations of completely regular pseudocompact frames. The first is an extension to frames of characterizations of completely regular pseudocompact spaces given by Väänänen. We follow with an embedding-type characterization stating that a completely regular frame is pseudocompact if and only if it is a P-quotient of its Stone-Čech compactification. We then give a characterization in terms of ideals in the cozero parts of the frames concerned. This characterization seems to be new and its spatial counterpart does not seem to have been observed before. We also define relatively pseudocompact quotients, and show that a necessary and sufficient condition for a completely regular frame to be pseudocompact is that it be relatively pseudocompact in its Hewitt realcompactification. Consequently a proof of a result of Banaschewski and Gilmour that a completely regular frame is pseudocompact if and only if its Hewitt realcompactification is compact, is presented without the invocation of the Boolean Ultrafilter Theorem.
- Full Text:
- Date Issued: 2007
- Authors: Dube, T , Matutu, Phethiwe P
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6783 , http://hdl.handle.net/10962/d1006926
- Description: We present several characterizations of completely regular pseudocompact frames. The first is an extension to frames of characterizations of completely regular pseudocompact spaces given by Väänänen. We follow with an embedding-type characterization stating that a completely regular frame is pseudocompact if and only if it is a P-quotient of its Stone-Čech compactification. We then give a characterization in terms of ideals in the cozero parts of the frames concerned. This characterization seems to be new and its spatial counterpart does not seem to have been observed before. We also define relatively pseudocompact quotients, and show that a necessary and sufficient condition for a completely regular frame to be pseudocompact is that it be relatively pseudocompact in its Hewitt realcompactification. Consequently a proof of a result of Banaschewski and Gilmour that a completely regular frame is pseudocompact if and only if its Hewitt realcompactification is compact, is presented without the invocation of the Boolean Ultrafilter Theorem.
- Full Text:
- Date Issued: 2007
A fuzzy classification technique for predicting species' distributions: applications using invasive alien plants and indigenous insects
- Robertson, Mark P, Villet, Martin H, Palmer, Anthony R
- Authors: Robertson, Mark P , Villet, Martin H , Palmer, Anthony R
- Date: 2004
- Language: English
- Type: text , Article
- Identifier: vital:6897 , http://hdl.handle.net/10962/d1011659 , http://dx.doi.org/10.1111/j.1366-9516.2004.00108.x
- Description: A new predictive modelling technique called the fuzzy envelope model (FEM) is introduced. The technique can be used to predict potential distributions of organisms using presence-only locality records and a set of environmental predictor variables. FEM uses fuzzy logic to classify a set of predictor variable maps based on the values associated with presence records and combines the results to produce a potential distribution map for a target species. This technique represents several refinements of the envelope approach used in the BIOCLIM modelling package. These refinements are related to the way in which FEMs deal with uncertainty, the way in which this uncertainty is represented in the resultant potential distribution maps, and the way that these maps can be interpreted and applied. To illustrate its potential use in biogeographical studies, FEM was applied to predicting the potential distribution of three invasive alien plant species (Lantana camara L., Ricinus communis L. and Solanum mauritianum Scop.), and three native cicada species (Capicada decora Germar, Platypleura deusta Thun. and P. capensis L.) in South Africa, Lesotho and Swaziland. These models were quantitatively compared with models produced by means of the algorithm used in the BIOCLIM modelling package, which is referred to as a crisp envelope model (the CEM design). The average performance of models of the FEM design was consistently higher than those of the CEM design. There were significant differences in model performance among species but there was no significant interaction between model design and species. The average maximum kappa value ranged from 0.70 to 0.90 for FEM design and from 0.57 to 0.89 for the CEM design, which can be described as 'good' to 'excellent' using published ranges of agreement for the kappa statistic. This technique can be used to predict species' potential distributions that could be used for identifying regions at risk from invasion by alien species. These predictions could also be used in conservation planning in the case of native species.
- Full Text:
- Date Issued: 2004
- Authors: Robertson, Mark P , Villet, Martin H , Palmer, Anthony R
- Date: 2004
- Language: English
- Type: text , Article
- Identifier: vital:6897 , http://hdl.handle.net/10962/d1011659 , http://dx.doi.org/10.1111/j.1366-9516.2004.00108.x
- Description: A new predictive modelling technique called the fuzzy envelope model (FEM) is introduced. The technique can be used to predict potential distributions of organisms using presence-only locality records and a set of environmental predictor variables. FEM uses fuzzy logic to classify a set of predictor variable maps based on the values associated with presence records and combines the results to produce a potential distribution map for a target species. This technique represents several refinements of the envelope approach used in the BIOCLIM modelling package. These refinements are related to the way in which FEMs deal with uncertainty, the way in which this uncertainty is represented in the resultant potential distribution maps, and the way that these maps can be interpreted and applied. To illustrate its potential use in biogeographical studies, FEM was applied to predicting the potential distribution of three invasive alien plant species (Lantana camara L., Ricinus communis L. and Solanum mauritianum Scop.), and three native cicada species (Capicada decora Germar, Platypleura deusta Thun. and P. capensis L.) in South Africa, Lesotho and Swaziland. These models were quantitatively compared with models produced by means of the algorithm used in the BIOCLIM modelling package, which is referred to as a crisp envelope model (the CEM design). The average performance of models of the FEM design was consistently higher than those of the CEM design. There were significant differences in model performance among species but there was no significant interaction between model design and species. The average maximum kappa value ranged from 0.70 to 0.90 for FEM design and from 0.57 to 0.89 for the CEM design, which can be described as 'good' to 'excellent' using published ranges of agreement for the kappa statistic. This technique can be used to predict species' potential distributions that could be used for identifying regions at risk from invasion by alien species. These predictions could also be used in conservation planning in the case of native species.
- Full Text:
- Date Issued: 2004
A preliminary survey of the estuaries on the south coast of South Africa, Robberg Peninsula - Cape St Francis, with particular reference to the fish fauna : ecological overview article
- James, Nicola Caroline, Harrison, T D
- Authors: James, Nicola Caroline , Harrison, T D
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:7144 , http://hdl.handle.net/10962/d1011842
- Description: A basic ichthyofaunal and physico-chemical survey of the coastal outlets on the south coast of South Africa (Robberg Peninsula to Cape St Francis) was undertaken during November 1994 and September 1995. Some 27 systems were identified along this stretch of coast and of these, 48% (Brak, Helpmekaars, Klip, Witels, Geelhoutbos, Kleinbos, Bruglaagte, Langbos, Sanddrif, Eerste, Boskloof, Kaapsedrif and Klipdrif [Wes]) comprised the inlets of coastal streams that offer little habitat for fishes, 26% (Sout, Bloukrans, Lottering, Elandsbos, Storms, Elands and Groot [Oos]) are located within deeply incised valleys within the Tsitsikamma region and provide limited littoral habitat for estuary-associated fishes; 26% of the systems (Piesang, Keurbooms, Matjies, Groot [Wes], Tsitsikamma, Klipdrif [Oos], Slang) appear to serve some estuarine function for both marine migrant and resident species although some of these may also be limited due to their small size and infrequent connection with the sea. This study serves to emphasize the ecological importance of these latter estuaries within this coastal sector.
- Full Text:
- Date Issued: 2009
- Authors: James, Nicola Caroline , Harrison, T D
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:7144 , http://hdl.handle.net/10962/d1011842
- Description: A basic ichthyofaunal and physico-chemical survey of the coastal outlets on the south coast of South Africa (Robberg Peninsula to Cape St Francis) was undertaken during November 1994 and September 1995. Some 27 systems were identified along this stretch of coast and of these, 48% (Brak, Helpmekaars, Klip, Witels, Geelhoutbos, Kleinbos, Bruglaagte, Langbos, Sanddrif, Eerste, Boskloof, Kaapsedrif and Klipdrif [Wes]) comprised the inlets of coastal streams that offer little habitat for fishes, 26% (Sout, Bloukrans, Lottering, Elandsbos, Storms, Elands and Groot [Oos]) are located within deeply incised valleys within the Tsitsikamma region and provide limited littoral habitat for estuary-associated fishes; 26% of the systems (Piesang, Keurbooms, Matjies, Groot [Wes], Tsitsikamma, Klipdrif [Oos], Slang) appear to serve some estuarine function for both marine migrant and resident species although some of these may also be limited due to their small size and infrequent connection with the sea. This study serves to emphasize the ecological importance of these latter estuaries within this coastal sector.
- Full Text:
- Date Issued: 2009
A synopsis of the Afrotropical Tricorythidae
- Authors: Barber-James, Helen M
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:7003 , http://hdl.handle.net/10962/d1008362
- Description: The Tricorythidae of the Afrotropical Region is currently composed of five described genera, three of which are thought to be restricted to Madagascar (Madecassorythus Elouard and Oliarioniny, Ranorythus Oliarinony and Elouard, and Spinirythus Oliarinony and Elouard), one which is restricted to Africa (Dicercomyzon Demoulin), and one which is thought to be distributed on both landmasses (Tricorythus Eaton). Based on sexual dimorphism, manifest in the relative eye size of mature male and female nymphs and adults and on the structure of the genitalia of adult males, it is proposed that there are two additional genera in Africa, as yet undescribed. One of these genera is represented by a species currently placed in Tricorythus (T. discolor [Burmeister]). Several other undescribed species within South Africa have been identified as belonging to the group. A second lineage is represented by Tricorythus tinctus Kimmins, from Uganda, the only currently described species. There are also several more undescribed species of this group widespread in Africa.
- Full Text:
- Date Issued: 2008
- Authors: Barber-James, Helen M
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:7003 , http://hdl.handle.net/10962/d1008362
- Description: The Tricorythidae of the Afrotropical Region is currently composed of five described genera, three of which are thought to be restricted to Madagascar (Madecassorythus Elouard and Oliarioniny, Ranorythus Oliarinony and Elouard, and Spinirythus Oliarinony and Elouard), one which is restricted to Africa (Dicercomyzon Demoulin), and one which is thought to be distributed on both landmasses (Tricorythus Eaton). Based on sexual dimorphism, manifest in the relative eye size of mature male and female nymphs and adults and on the structure of the genitalia of adult males, it is proposed that there are two additional genera in Africa, as yet undescribed. One of these genera is represented by a species currently placed in Tricorythus (T. discolor [Burmeister]). Several other undescribed species within South Africa have been identified as belonging to the group. A second lineage is represented by Tricorythus tinctus Kimmins, from Uganda, the only currently described species. There are also several more undescribed species of this group widespread in Africa.
- Full Text:
- Date Issued: 2008
Above ground woody community attributes, biomass and carbon stocks along a rainfall gradient in the savannas of the central lowveld, South Africa
- Shackleton, Charlie M, Scholes, Robert J
- Authors: Shackleton, Charlie M , Scholes, Robert J
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6658 , http://hdl.handle.net/10962/d1007079
- Description: Enumeration of carbon stocks at benchmark sites is a necessary activity in assessing the potential carbon sequestration and possible generation of credits through restoration of intensively impacted sites. However, there is a lack of empirical studies throughout much of the savannas of sub-Saharan Africa, including South Africa. We report an estimation of species specific and site biomass and carbon stocks, and general vegetation structural attributes from three protected areas along a rainfall gradient in the central lowveld, South Africa. Estimates of biomass and carbon stocks were effected through destructive sampling to establish locally derived allometric equations. There was a gradient of increasing woody density, height of the canopy, number of species, density of regenerative stems and a greater proportion of stems in small size classes from the arid locality to the mesic locality, with the semi-arid locality being intermediate. The proportion of spinescent species decreased with increasing rainfall. The mesic locality was significantly more woody than either the arid or semi-arid sites, having double the biomass, four times the density and 40% higher basal area. Above ground carbon pools were also higher; carbon stocks were approximately 9 t/ha for the arid and semi-arid sites and 18 t/ha for the mesic site.
- Full Text:
- Date Issued: 2011
- Authors: Shackleton, Charlie M , Scholes, Robert J
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6658 , http://hdl.handle.net/10962/d1007079
- Description: Enumeration of carbon stocks at benchmark sites is a necessary activity in assessing the potential carbon sequestration and possible generation of credits through restoration of intensively impacted sites. However, there is a lack of empirical studies throughout much of the savannas of sub-Saharan Africa, including South Africa. We report an estimation of species specific and site biomass and carbon stocks, and general vegetation structural attributes from three protected areas along a rainfall gradient in the central lowveld, South Africa. Estimates of biomass and carbon stocks were effected through destructive sampling to establish locally derived allometric equations. There was a gradient of increasing woody density, height of the canopy, number of species, density of regenerative stems and a greater proportion of stems in small size classes from the arid locality to the mesic locality, with the semi-arid locality being intermediate. The proportion of spinescent species decreased with increasing rainfall. The mesic locality was significantly more woody than either the arid or semi-arid sites, having double the biomass, four times the density and 40% higher basal area. Above ground carbon pools were also higher; carbon stocks were approximately 9 t/ha for the arid and semi-arid sites and 18 t/ha for the mesic site.
- Full Text:
- Date Issued: 2011
Assessment of topical corticosteroid preparations: the human skin-blanching assay
- Haigh, John M, Kanfer, Isadore
- Authors: Haigh, John M , Kanfer, Isadore
- Date: 1984
- Language: English
- Type: text , Article
- Identifier: vital:6374 , http://hdl.handle.net/10962/d1006284
- Description: (From the introduction) Since the introduction of topical corticosteroid formulations, their use has become widespread, being prescribed for a large variety of dermatological conditions. This widespread use has created a need for a reliable method of assessing the various dosage forms of these compounds. Clinical trials are laborious, costly and difficult to mount as well as being impractical for the screening of large numbers of drugs. Patients suffering from dermatological complaints are not ideal subjects for the testing of topical corticosteroid preparations as it is difficult to obtain standardized lesions which are necessary for the comparison of results between patients (Baker and Sattar, 1968). For these reasons a number of methods have been developed for the screening of novel corticosteroids and testing of topical corticosteroid formulations.
- Full Text:
- Date Issued: 1984
- Authors: Haigh, John M , Kanfer, Isadore
- Date: 1984
- Language: English
- Type: text , Article
- Identifier: vital:6374 , http://hdl.handle.net/10962/d1006284
- Description: (From the introduction) Since the introduction of topical corticosteroid formulations, their use has become widespread, being prescribed for a large variety of dermatological conditions. This widespread use has created a need for a reliable method of assessing the various dosage forms of these compounds. Clinical trials are laborious, costly and difficult to mount as well as being impractical for the screening of large numbers of drugs. Patients suffering from dermatological complaints are not ideal subjects for the testing of topical corticosteroid preparations as it is difficult to obtain standardized lesions which are necessary for the comparison of results between patients (Baker and Sattar, 1968). For these reasons a number of methods have been developed for the screening of novel corticosteroids and testing of topical corticosteroid formulations.
- Full Text:
- Date Issued: 1984
Codeswitching, borrowing and mixing in a corpus of Xhosa English
- Authors: De Klerk, Vivian A
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6130 , http://hdl.handle.net/10962/d1011582
- Description: The paper analyses selected aspects of the codeswitching behaviour in a spoken corpus of the English of 326 people, all of them mother-tongue speakers of Xhosa (a local African language in South Africa), and all of whom would see themselves as Xhosa/English bilinguals. The corpus comprises approximately 550,000 transcribed words of spontaneous, relaxed, oral discourse in English between pairs of Xhosaspeaking interlocutors, discussing a wide range of topics. While the usual pattern in bilingual speech is to use the L1 as matrix language and the L2 as embedded language, in this corpus the opposite is the case, as interlocutors were interviewed in English (the L2). The corpus therefore offers a ‘mirror image’, in a sense, of normal codeswitching behaviour. Using Wordsmith (a concordancer programme), all incidences of codeswitching into Xhosa during these conversations were identified and analysed in an effort to reveal underlying patterns. Examination of the amount and nature of codeswitching in the corpus promised to throw some light on the extent to which participants are genuinely bilingual, in terms of their ability to converse comfortably in English.
- Full Text:
- Date Issued: 2006
- Authors: De Klerk, Vivian A
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6130 , http://hdl.handle.net/10962/d1011582
- Description: The paper analyses selected aspects of the codeswitching behaviour in a spoken corpus of the English of 326 people, all of them mother-tongue speakers of Xhosa (a local African language in South Africa), and all of whom would see themselves as Xhosa/English bilinguals. The corpus comprises approximately 550,000 transcribed words of spontaneous, relaxed, oral discourse in English between pairs of Xhosaspeaking interlocutors, discussing a wide range of topics. While the usual pattern in bilingual speech is to use the L1 as matrix language and the L2 as embedded language, in this corpus the opposite is the case, as interlocutors were interviewed in English (the L2). The corpus therefore offers a ‘mirror image’, in a sense, of normal codeswitching behaviour. Using Wordsmith (a concordancer programme), all incidences of codeswitching into Xhosa during these conversations were identified and analysed in an effort to reveal underlying patterns. Examination of the amount and nature of codeswitching in the corpus promised to throw some light on the extent to which participants are genuinely bilingual, in terms of their ability to converse comfortably in English.
- Full Text:
- Date Issued: 2006
Cognitive therapy and the restructuring of early memories through guided imagery
- Authors: Edwards, D J A
- Date: 1990
- Language: English
- Type: Article
- Identifier: vital:6241 , http://hdl.handle.net/10962/d1007853
- Description: This article describes the application of a guided imagery psychodrama technique to emotionally charged early memories. Such memories provide access to core schemata about the self and social relationships. Two case studies illustrate how the imagery technique enables the therapist to identify and restructure key cognitions out of which the schemata are constructed. The need for techniques to modify developmentally primitive schemata is discussed. Examples are given of ways to assist the patient in confronting the strong affect that may be aroused and in dealing with cognitions that block the process. Effectiveness is discussed in terms of the contribution of a guided imagery session to the overall process of ''learning to learn'' that takes place in cognitive psychotherapy.
- Full Text: false
- Date Issued: 1990
- Authors: Edwards, D J A
- Date: 1990
- Language: English
- Type: Article
- Identifier: vital:6241 , http://hdl.handle.net/10962/d1007853
- Description: This article describes the application of a guided imagery psychodrama technique to emotionally charged early memories. Such memories provide access to core schemata about the self and social relationships. Two case studies illustrate how the imagery technique enables the therapist to identify and restructure key cognitions out of which the schemata are constructed. The need for techniques to modify developmentally primitive schemata is discussed. Examples are given of ways to assist the patient in confronting the strong affect that may be aroused and in dealing with cognitions that block the process. Effectiveness is discussed in terms of the contribution of a guided imagery session to the overall process of ''learning to learn'' that takes place in cognitive psychotherapy.
- Full Text: false
- Date Issued: 1990
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:
- Date Issued: 2009
- 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:
- Date Issued: 2009
Electrochemical properties of benzylmercapto and dodecylmercapto tetra substituted nickel phthalocyanine complexes: Electrocatalytic oxidation of nitrite
- Agboola, Bolade O, Ozoemena, Kenneth I, Nyokong, Tebello
- Authors: Agboola, Bolade O , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6562 , http://hdl.handle.net/10962/d1003826
- Description: Nickel tetrakis(benzylmercapto)phthalocyanine (NiTBMPc) and nickel tetrakis(dodecylmercapto)phthalocyanine (NiTDMPc) complexes were synthesized and their spectral and electrochemical properties reported. The CV showed four or five redox processes for NiTBMPc and NiTDMPc, respectively. For the first time, spectroelectrochemistry gave evidence for the formation of NiII/NiI process in a NiPc complex. The rest of the processes were ring based. The NiTBMPc complex was successfully deposited on both gold and glassy carbon electrodes by electropolymerisation while NiTDMPc complex was deposited on gold electrode only. The films were electro-transformed in aqueous 0.1 M NaOH solution to the O–Ni–O oxo bridged form. The modified electrodes were characterized using electrochemical impedance spectroscopy and the results showed typical behavior for modified electrodes. Electrodes with poly-Ni(OH)Pcs films exhibited higher charge transfer resistance values, Rp than their corresponding poly-NiPcs films counterparts. All the modified electrodes showed improved catalytic activities than the unmodified electrodes towards nitrite ions electrooxidation. Better catalytic activities were observed for the modified electrodes when they were transformed to O–Ni–O oxo bridge form. All the modified electrodes exhibited high resistance to electrode surface passivation.
- Full Text:
- Date Issued: 2006
- Authors: Agboola, Bolade O , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6562 , http://hdl.handle.net/10962/d1003826
- Description: Nickel tetrakis(benzylmercapto)phthalocyanine (NiTBMPc) and nickel tetrakis(dodecylmercapto)phthalocyanine (NiTDMPc) complexes were synthesized and their spectral and electrochemical properties reported. The CV showed four or five redox processes for NiTBMPc and NiTDMPc, respectively. For the first time, spectroelectrochemistry gave evidence for the formation of NiII/NiI process in a NiPc complex. The rest of the processes were ring based. The NiTBMPc complex was successfully deposited on both gold and glassy carbon electrodes by electropolymerisation while NiTDMPc complex was deposited on gold electrode only. The films were electro-transformed in aqueous 0.1 M NaOH solution to the O–Ni–O oxo bridged form. The modified electrodes were characterized using electrochemical impedance spectroscopy and the results showed typical behavior for modified electrodes. Electrodes with poly-Ni(OH)Pcs films exhibited higher charge transfer resistance values, Rp than their corresponding poly-NiPcs films counterparts. All the modified electrodes showed improved catalytic activities than the unmodified electrodes towards nitrite ions electrooxidation. Better catalytic activities were observed for the modified electrodes when they were transformed to O–Ni–O oxo bridge form. All the modified electrodes exhibited high resistance to electrode surface passivation.
- Full Text:
- Date Issued: 2006
Estimating rainfall and water balance over the Okavango River Basin for hydrological applications
- Wilk, J, Kniveton, D, Andersson, L, Layberry, R, Todd, M C, Hughes, Denis A
- Authors: Wilk, J , Kniveton, D , Andersson, L , Layberry, R , Todd, M C , Hughes, Denis A
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:7084 , http://hdl.handle.net/10962/d1012343 , http://dx.doi.org/10.1016/j.jhydrol.2006.04.049
- Description: A historical database for use in rainfall-runoff modeling of the Okavango River Basin in Southwest Africa is presented. The work has relevance for similar data-sparse regions. The parameters of main concern are rainfall and catchment water balance, which are key variables for subsequent studies of the hydrological impacts of development and climate change. Rainfall estimates are based on a combination of in situ gauges and satellite sources. Rain gauge measurements are most extensive from 1955 to 1972, after which they are drastically reduced due to the Angolan civil war. The sensitivity of the rainfall fields to spatial interpolation techniques and the density of gauges were evaluated. Satellite based rainfall estimates for the basin are developed for the period from 1991 onwards, based on the Tropical Rainfall Measuring Mission (TRMM) and Special Sensor Microwave Imager (SSM/I) datasets. The consistency between the gauges and satellite estimates was considered. A methodology was developed to allow calibration of the rainfall-runoff hydrological model against rain gauge data from 1960 to 1972, with the prerequisite that the model should be driven by satellite derived rainfall products from 1990 onwards. With the rain gauge data, addition of a single rainfall station (Longa) in regions where stations earlier were lacking was more important than the chosen interpolation method. Comparison of satellite and gauge rainfall outside the basin indicated that the satellite overestimates rainfall by 20%. A non-linear correction was derived by fitting the rainfall frequency characteristics to those of the historical rainfall data. This satellite rainfall dataset was found satisfactory when using the Pitman rainfall-runoff model (Hughes, D., Andersson, L., Wilk, J., Savenije, H.H.G., this issue. Regional calibration of the Pitman model for the Okavango River. Journal of Hydrology). Intensive monitoring in the region is recommended to increase accuracy of the comprehensive satellite rainfall estimate calibration procedure.
- Full Text:
- Date Issued: 2006
- Authors: Wilk, J , Kniveton, D , Andersson, L , Layberry, R , Todd, M C , Hughes, Denis A
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:7084 , http://hdl.handle.net/10962/d1012343 , http://dx.doi.org/10.1016/j.jhydrol.2006.04.049
- Description: A historical database for use in rainfall-runoff modeling of the Okavango River Basin in Southwest Africa is presented. The work has relevance for similar data-sparse regions. The parameters of main concern are rainfall and catchment water balance, which are key variables for subsequent studies of the hydrological impacts of development and climate change. Rainfall estimates are based on a combination of in situ gauges and satellite sources. Rain gauge measurements are most extensive from 1955 to 1972, after which they are drastically reduced due to the Angolan civil war. The sensitivity of the rainfall fields to spatial interpolation techniques and the density of gauges were evaluated. Satellite based rainfall estimates for the basin are developed for the period from 1991 onwards, based on the Tropical Rainfall Measuring Mission (TRMM) and Special Sensor Microwave Imager (SSM/I) datasets. The consistency between the gauges and satellite estimates was considered. A methodology was developed to allow calibration of the rainfall-runoff hydrological model against rain gauge data from 1960 to 1972, with the prerequisite that the model should be driven by satellite derived rainfall products from 1990 onwards. With the rain gauge data, addition of a single rainfall station (Longa) in regions where stations earlier were lacking was more important than the chosen interpolation method. Comparison of satellite and gauge rainfall outside the basin indicated that the satellite overestimates rainfall by 20%. A non-linear correction was derived by fitting the rainfall frequency characteristics to those of the historical rainfall data. This satellite rainfall dataset was found satisfactory when using the Pitman rainfall-runoff model (Hughes, D., Andersson, L., Wilk, J., Savenije, H.H.G., this issue. Regional calibration of the Pitman model for the Okavango River. Journal of Hydrology). Intensive monitoring in the region is recommended to increase accuracy of the comprehensive satellite rainfall estimate calibration procedure.
- Full Text:
- Date Issued: 2006
Minding the gaps – an investigation into language policy and practice in four Eastern Cape districts
- Probyn, Margie, Murray, Sarah, Botha, Liz, Botya, Paula, Brookes, Margie, Westphal, Vivian
- Authors: Probyn, Margie , Murray, Sarah , Botha, Liz , Botya, Paula , Brookes, Margie , Westphal, Vivian
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6109 , http://hdl.handle.net/10962/d1009739
- Description: South Africa's new Language in Education Policy (LiEP) has been described as one of the most progressive in the world but few schools have implemented it. This article describes research that investigates the gap between the policy goals and what is actually happening in schools in four districts in the Eastern Cape. The research attempts to make explicit community and school language practices and the factors that support or frustrate the formation and enactment of a school language policy in these four linguistically diverse sites. It appears that school governing bodies are not well equipped to make decisions about school language policy which meet the requirements of the national LiEP and economic imperatives to acquire English override considerations of multilingualism and additive bilingualism as expressed in the policy.
- Full Text:
- Date Issued: 2002
Minding the gaps – an investigation into language policy and practice in four Eastern Cape districts
- Authors: Probyn, Margie , Murray, Sarah , Botha, Liz , Botya, Paula , Brookes, Margie , Westphal, Vivian
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6109 , http://hdl.handle.net/10962/d1009739
- Description: South Africa's new Language in Education Policy (LiEP) has been described as one of the most progressive in the world but few schools have implemented it. This article describes research that investigates the gap between the policy goals and what is actually happening in schools in four districts in the Eastern Cape. The research attempts to make explicit community and school language practices and the factors that support or frustrate the formation and enactment of a school language policy in these four linguistically diverse sites. It appears that school governing bodies are not well equipped to make decisions about school language policy which meet the requirements of the national LiEP and economic imperatives to acquire English override considerations of multilingualism and additive bilingualism as expressed in the policy.
- Full Text:
- Date Issued: 2002
Minding the gaps – an investigation into language policy and practice in four Eastern Cape districts
- Probyn, Margie J, Murray, Sarah R, Botha, Liz, Botya, Paula, Brookes, Margie, Westphal, Vivian
- Authors: Probyn, Margie J , Murray, Sarah R , Botha, Liz , Botya, Paula , Brookes, Margie , Westphal, Vivian
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:7024 , http://hdl.handle.net/10962/d1007206
- Description: South Africa's new Language in Education Policy (LiEP) has been described as one of the most progressive in the world but few schools have implemented it. This article describes research that investigates the gap between the policy goals and what is actually happening in schools in four districts in the Eastern Cape. The research attempts to make explicit community and school language practices and the factors that support or frustrate the formation and enactment of a school language policy in these four linguistically diverse sites. It appears that school governing bodies are not well equipped to make decisions about school language policy which meet the requirements of the national LiEP and economic imperatives to acquire English override considerations of multilingualism and additive bilingualism as expressed in the policy.
- Full Text:
- Date Issued: 2002
Minding the gaps – an investigation into language policy and practice in four Eastern Cape districts
- Authors: Probyn, Margie J , Murray, Sarah R , Botha, Liz , Botya, Paula , Brookes, Margie , Westphal, Vivian
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:7024 , http://hdl.handle.net/10962/d1007206
- Description: South Africa's new Language in Education Policy (LiEP) has been described as one of the most progressive in the world but few schools have implemented it. This article describes research that investigates the gap between the policy goals and what is actually happening in schools in four districts in the Eastern Cape. The research attempts to make explicit community and school language practices and the factors that support or frustrate the formation and enactment of a school language policy in these four linguistically diverse sites. It appears that school governing bodies are not well equipped to make decisions about school language policy which meet the requirements of the national LiEP and economic imperatives to acquire English override considerations of multilingualism and additive bilingualism as expressed in the policy.
- Full Text:
- Date Issued: 2002
Rapid UPLC - MS/MS method for the determination of ketoprofen in human dermal microdialysis samples
- Tettey-Amlalo, Ralph N O, Kanfer, Isadore
- Authors: Tettey-Amlalo, Ralph N O , Kanfer, Isadore
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6444 , http://hdl.handle.net/10962/d1006631
- Description: Dermal microdialysis (DMD) is a technique capable of determining the percutaneous penetration of drugs from topical formulations intended for local and/or regional activity. Typically, the concentrations of drug collected in dialysates are very low, generally in the ng/ml or even pg/ml range. An additional challenge is the very low volume of sample collected at each collection time and which can range from 1 to 30 μl only. Hence the objective was to develop and validate a rapid, accurate, precise, reproducible and highly sensitive LC–MS/MS method for the quantitative analysis of ketoprofen (KET) in dialystes following application of a topical gel product to the skin of human subjects. UPLC–MS/MS was used and KET was separated on an Acquity™ UPLC BEH C18 column (100 mm × 2.1 mm i.d., 1.7 μm) and analysed in negative-ion (NI) electrospray ionisation (ESI) mode. The mobile phase (MP) consisted of acetonitrile:methanol:water (60:20:20, v/v/v) under isocratic conditions at a flow rate of 0.3 ml/min. Samples were extracted using ethyl acetate with ibuprofen (IBU) as internal standard (IS) and the organic solvent was then evaporated to dryness and the residue re-constituted in methanol. 5 μl samples were injected and analysis was performed at ambient temperature 22 ± 0.5 °C. KET and IBU eluted at 1.07 and 1.49 min, respectively. KET and IBU responses were optimised at the transitions 253.00 > 209.00 and 205.00 > 161.00, respectively. Calibration curves were linear over the range 0.5–500 ng/ml with correlation coefficients > 0.999. The accuracy and precision of the method were found to be between 99.97% and 104.67% (R.S.D. < 2%) and the mean recovery of KET from normal saline was 88.03 ± 0.3% (R.S.D. < 2.20%). The LLOQ and LOD values were found to be 0.5 and 0.1 ng/ml respectively whereas the ULOD was set at 500 ng/ml. The method was successfully applied to determine the bioavailability of KET following application of topical KET gel, Fastum® gel, to the skin of human volunteers.
- Full Text:
- Date Issued: 2009
- Authors: Tettey-Amlalo, Ralph N O , Kanfer, Isadore
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6444 , http://hdl.handle.net/10962/d1006631
- Description: Dermal microdialysis (DMD) is a technique capable of determining the percutaneous penetration of drugs from topical formulations intended for local and/or regional activity. Typically, the concentrations of drug collected in dialysates are very low, generally in the ng/ml or even pg/ml range. An additional challenge is the very low volume of sample collected at each collection time and which can range from 1 to 30 μl only. Hence the objective was to develop and validate a rapid, accurate, precise, reproducible and highly sensitive LC–MS/MS method for the quantitative analysis of ketoprofen (KET) in dialystes following application of a topical gel product to the skin of human subjects. UPLC–MS/MS was used and KET was separated on an Acquity™ UPLC BEH C18 column (100 mm × 2.1 mm i.d., 1.7 μm) and analysed in negative-ion (NI) electrospray ionisation (ESI) mode. The mobile phase (MP) consisted of acetonitrile:methanol:water (60:20:20, v/v/v) under isocratic conditions at a flow rate of 0.3 ml/min. Samples were extracted using ethyl acetate with ibuprofen (IBU) as internal standard (IS) and the organic solvent was then evaporated to dryness and the residue re-constituted in methanol. 5 μl samples were injected and analysis was performed at ambient temperature 22 ± 0.5 °C. KET and IBU eluted at 1.07 and 1.49 min, respectively. KET and IBU responses were optimised at the transitions 253.00 > 209.00 and 205.00 > 161.00, respectively. Calibration curves were linear over the range 0.5–500 ng/ml with correlation coefficients > 0.999. The accuracy and precision of the method were found to be between 99.97% and 104.67% (R.S.D. < 2%) and the mean recovery of KET from normal saline was 88.03 ± 0.3% (R.S.D. < 2.20%). The LLOQ and LOD values were found to be 0.5 and 0.1 ng/ml respectively whereas the ULOD was set at 500 ng/ml. The method was successfully applied to determine the bioavailability of KET following application of topical KET gel, Fastum® gel, to the skin of human volunteers.
- Full Text:
- Date Issued: 2009
Repositioning Renaissance studies in South Africa: strategic thinking or 'business-as-usual
- Authors: Wright, Laurence
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:7054 , http://hdl.handle.net/10962/d1007415
- Description: Increasingly, in many leading South African tertiary departments of literature, early modern studies have a fairly slim hold on the core curriculum. More and more, departmental offerings concentrate on nineteenth and twentieth century literature, perhaps in the belief either that today’s students are so poorly prepared that they will never be able to cope with the mental shifts necessary to appreciate pre-industrial literature and its language, or, worse, that nothing before the C19 colonial incursion into South Africa can really matter very much to undergraduates. Whatever the reason, in such departments, it is no longer possible to get to grips with the contribution of the renaissance to the formation of the modern world. The significance of the broader nomenclature, early modern studies, doesn’t appear to strike home, especially the point that, if students want to understand the world we live in, they have to know this period particularly well. Indeed, they need to have some idea of the interaction between early modern Europe and the literature and ideas of the ancient civilizations of Rome and Greece. If we fail them in this regard, as I believe we are doing to an increasing extent, the result will be generations of intellectual sleepwalkers, denizens of mental landscapes they are responding to, or ‘reading’, in terms of an inner life unaware of important historical continuities and disjunctions; cut off, moreover, from understanding essential features of modernity.
- Full Text:
- Date Issued: 2006
- Authors: Wright, Laurence
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:7054 , http://hdl.handle.net/10962/d1007415
- Description: Increasingly, in many leading South African tertiary departments of literature, early modern studies have a fairly slim hold on the core curriculum. More and more, departmental offerings concentrate on nineteenth and twentieth century literature, perhaps in the belief either that today’s students are so poorly prepared that they will never be able to cope with the mental shifts necessary to appreciate pre-industrial literature and its language, or, worse, that nothing before the C19 colonial incursion into South Africa can really matter very much to undergraduates. Whatever the reason, in such departments, it is no longer possible to get to grips with the contribution of the renaissance to the formation of the modern world. The significance of the broader nomenclature, early modern studies, doesn’t appear to strike home, especially the point that, if students want to understand the world we live in, they have to know this period particularly well. Indeed, they need to have some idea of the interaction between early modern Europe and the literature and ideas of the ancient civilizations of Rome and Greece. If we fail them in this regard, as I believe we are doing to an increasing extent, the result will be generations of intellectual sleepwalkers, denizens of mental landscapes they are responding to, or ‘reading’, in terms of an inner life unaware of important historical continuities and disjunctions; cut off, moreover, from understanding essential features of modernity.
- Full Text:
- Date Issued: 2006
Rural self-reliance strategies in South Africa : community initiatives and external support in the former black homelands
- Authors: Nel, Etienne L , Binns, Tony
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:6716 , http://hdl.handle.net/10962/d1006789
- Description: This paper examines the relevance of the concept of self-reliance in the context of rural community economic development in South Africa. Whilst changing global and local circumstances oblige impoverished communities to become more pro-active in the enhancement of the quality of their lives, they nevertheless cannot ignore basic market forces and the need for an appropriate level of external assistance. Four community-based agricultural ventures in South Africa's former Homelands are examined. A comparison between the four schemes permits an assessment to be made of what such community ventures require if they are to succeed and have a meaningful impact on job creation and poverty alleviation. The role of external support agencies and access to markets in each case features prominently in the assessment.
- Full Text:
- Date Issued: 2000
- Authors: Nel, Etienne L , Binns, Tony
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:6716 , http://hdl.handle.net/10962/d1006789
- Description: This paper examines the relevance of the concept of self-reliance in the context of rural community economic development in South Africa. Whilst changing global and local circumstances oblige impoverished communities to become more pro-active in the enhancement of the quality of their lives, they nevertheless cannot ignore basic market forces and the need for an appropriate level of external assistance. Four community-based agricultural ventures in South Africa's former Homelands are examined. A comparison between the four schemes permits an assessment to be made of what such community ventures require if they are to succeed and have a meaningful impact on job creation and poverty alleviation. The role of external support agencies and access to markets in each case features prominently in the assessment.
- Full Text:
- Date Issued: 2000
Social parasitism by honeybee workers (Apis mellifera capensis Escholtz): host finding and resistance of hybrid host colonies
- Neumann, Peter, Radloff, Sarah E, Moritz, Robin F A, Hepburn, H Randall, Reece, Sacha L
- Authors: Neumann, Peter , Radloff, Sarah E , Moritz, Robin F A , Hepburn, H Randall , Reece, Sacha L
- Date: 2001
- Language: English
- Type: text , Article
- Identifier: vital:6907 , http://hdl.handle.net/10962/d1011860
- Description: We studied possible host finding and resistance mechanisms of host colonies in the context of social parasitism by Cape honeybee (Apis mellifera capensis) workers. Workers often join neighboring colonies by drifting, but long-range drifting (dispersal) to colonies far away from the maternal nests also rarely occurs. We tested the impact of queenstate and taxon of mother and host colonies on drifting and dispersing of workers and on the hosting of these workers in A. m. capensis, A. m. scutellata, and their natural hybrids. Workers were paint-marked according to colony and reintroduced into their queenright or queenless mother colonies. After 10 days, 579 out of 12,034 labeled workers were recaptured in foreign colonies. We found that drifting and dispersing represent different behaviors, which were differently affected by taxon and queenstate of both mother and host colonies. Hybrid workers drifted more often than A. m. capensis and A. m. scutellata. However, A. m. capensis workers dispersed more often than A. m. scutellata and the hybrids combined, and A. m. scutellata workers also dispersed more frequently than the hybrids. Dispersers from queenright A. m. capensis colonies were more often found in queenless host colonies and vice versa, indicating active host searching and/or a queenstate-discriminating guarding mechanism. Our data show that A. m. capensis workers disperse significantly more often than other races of A. mellifera, suggesting that dispersing represents a host finding mechanism. The lack of dispersal in hybrids and different hosting mechanisms of foreign workers by hybrid colonies may also be responsible for the stability of the natural hybrid zone between A. m. capensis and A. m. scutellata.
- Full Text:
- Date Issued: 2001
- Authors: Neumann, Peter , Radloff, Sarah E , Moritz, Robin F A , Hepburn, H Randall , Reece, Sacha L
- Date: 2001
- Language: English
- Type: text , Article
- Identifier: vital:6907 , http://hdl.handle.net/10962/d1011860
- Description: We studied possible host finding and resistance mechanisms of host colonies in the context of social parasitism by Cape honeybee (Apis mellifera capensis) workers. Workers often join neighboring colonies by drifting, but long-range drifting (dispersal) to colonies far away from the maternal nests also rarely occurs. We tested the impact of queenstate and taxon of mother and host colonies on drifting and dispersing of workers and on the hosting of these workers in A. m. capensis, A. m. scutellata, and their natural hybrids. Workers were paint-marked according to colony and reintroduced into their queenright or queenless mother colonies. After 10 days, 579 out of 12,034 labeled workers were recaptured in foreign colonies. We found that drifting and dispersing represent different behaviors, which were differently affected by taxon and queenstate of both mother and host colonies. Hybrid workers drifted more often than A. m. capensis and A. m. scutellata. However, A. m. capensis workers dispersed more often than A. m. scutellata and the hybrids combined, and A. m. scutellata workers also dispersed more frequently than the hybrids. Dispersers from queenright A. m. capensis colonies were more often found in queenless host colonies and vice versa, indicating active host searching and/or a queenstate-discriminating guarding mechanism. Our data show that A. m. capensis workers disperse significantly more often than other races of A. mellifera, suggesting that dispersing represents a host finding mechanism. The lack of dispersal in hybrids and different hosting mechanisms of foreign workers by hybrid colonies may also be responsible for the stability of the natural hybrid zone between A. m. capensis and A. m. scutellata.
- Full Text:
- Date Issued: 2001
Stronger induction of callose deposition in barley by Russian wheat aphid than bird cherry-oat aphid is not associated with differences in callose synthase or ≤-1,3-glucanase expression
- Saheed, Sefiu A, Cierlik, Izabela, Larsson, Kristina A E, Delp, Gabriele, Bradley, Graeme, Jonsson, Lisbeth M V, Botha, Christiaan E J
- Authors: Saheed, Sefiu A , Cierlik, Izabela , Larsson, Kristina A E , Delp, Gabriele , Bradley, Graeme , Jonsson, Lisbeth M V , Botha, Christiaan E J
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6542 , http://hdl.handle.net/10962/d1005984
- Description: The effects of infestation by the bird cherry-oat aphid (BCA), (Rhopalosiphum padi L) and the Russian wheat aphid (RWA) (Diuraphis noxia Mordvilko) on callose deposition and gene expression related to callose accumulation were investigated in barley (Hordeum vulgare L. cv. Clipper). The BCA, which gives no visible symptoms, induced very limited callose deposition, even after 14 days of infestation. In contrast, RWA, which causes chlorosis, white and yellow streaking and leaf rolling, induced callose accumulation already after 24h in longitudinal leaf veins. The deposition was pronounced after 72 h, progressing during 7 and 14 days of infestation. In RWA-infested source leaves, callose was also induced in longitudinal veins basipetal to the aphid-infested tissue, whereas in sink leaves, more callose deposition was found above the feeding sites. Nine putative callose synthase genes were identified in a data base search, of which eight were expressed in the leaves, but with similar level of expression in control and aphid-infested tissue. Four out of 12 examined β-1,3-glucanases were expressed in the leaves, and three of them were up-regulated in aphid-infested tissue. They were all more strongly induced by RWA than BCA. The results suggest that callose accumulation may be partly responsible for the symptoms resulting from RWA feeding and that a callose-inducing signal may be transported in the phloem. Furthermore it is concluded that the absence of callose deposition in BCA-infested leaves is not due to a stronger induction of callose-degrading β-1,3-glucanases in this tissue, as compared to RWA-infested leaves.
- Full Text:
- Date Issued: 2009
- Authors: Saheed, Sefiu A , Cierlik, Izabela , Larsson, Kristina A E , Delp, Gabriele , Bradley, Graeme , Jonsson, Lisbeth M V , Botha, Christiaan E J
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6542 , http://hdl.handle.net/10962/d1005984
- Description: The effects of infestation by the bird cherry-oat aphid (BCA), (Rhopalosiphum padi L) and the Russian wheat aphid (RWA) (Diuraphis noxia Mordvilko) on callose deposition and gene expression related to callose accumulation were investigated in barley (Hordeum vulgare L. cv. Clipper). The BCA, which gives no visible symptoms, induced very limited callose deposition, even after 14 days of infestation. In contrast, RWA, which causes chlorosis, white and yellow streaking and leaf rolling, induced callose accumulation already after 24h in longitudinal leaf veins. The deposition was pronounced after 72 h, progressing during 7 and 14 days of infestation. In RWA-infested source leaves, callose was also induced in longitudinal veins basipetal to the aphid-infested tissue, whereas in sink leaves, more callose deposition was found above the feeding sites. Nine putative callose synthase genes were identified in a data base search, of which eight were expressed in the leaves, but with similar level of expression in control and aphid-infested tissue. Four out of 12 examined β-1,3-glucanases were expressed in the leaves, and three of them were up-regulated in aphid-infested tissue. They were all more strongly induced by RWA than BCA. The results suggest that callose accumulation may be partly responsible for the symptoms resulting from RWA feeding and that a callose-inducing signal may be transported in the phloem. Furthermore it is concluded that the absence of callose deposition in BCA-infested leaves is not due to a stronger induction of callose-degrading β-1,3-glucanases in this tissue, as compared to RWA-infested leaves.
- Full Text:
- Date Issued: 2009
The deployment of the medico-psychological gaze and disability expertise in relation to children with intellectual disability
- Mckenzie, Judith A, Macleod, Catriona I
- Authors: Mckenzie, Judith A , Macleod, Catriona I
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6294 , http://hdl.handle.net/10962/d1014732 , http://www.tandfonline.com/doi/full/10.1080/13603116.2010.540042
- Description: In this study, we adopt the concepts of Michel Foucault on the medical gaze and Nikolas Rose on psychological expertise to differentiate between two forms of expertise evident in the education of intellectually disabled children. We draw on a discourse analytic study carried out in South Africa on intellectual disability in relation to educational practice to examine the operation of a medico-psychological gaze that calls for disability expertise in the management of disability. We conclude our discussion by noting that the dichotomy between impairment and disability that is proposed in the social model of disability does little to destabilise the power of the medico-psychological gaze since impairment is conceded to biomedical knowledge as an object of positive knowledge. This tacit acceptance of the medical authority gives sanction to disability expertise that operates in diffuse ways to regulate the educational experience of learners with intellectual disability. The implications of this conception for inclusive education are briefly explored, and further areas for research are suggested.
- Full Text:
- Date Issued: 2012
- Authors: Mckenzie, Judith A , Macleod, Catriona I
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6294 , http://hdl.handle.net/10962/d1014732 , http://www.tandfonline.com/doi/full/10.1080/13603116.2010.540042
- Description: In this study, we adopt the concepts of Michel Foucault on the medical gaze and Nikolas Rose on psychological expertise to differentiate between two forms of expertise evident in the education of intellectually disabled children. We draw on a discourse analytic study carried out in South Africa on intellectual disability in relation to educational practice to examine the operation of a medico-psychological gaze that calls for disability expertise in the management of disability. We conclude our discussion by noting that the dichotomy between impairment and disability that is proposed in the social model of disability does little to destabilise the power of the medico-psychological gaze since impairment is conceded to biomedical knowledge as an object of positive knowledge. This tacit acceptance of the medical authority gives sanction to disability expertise that operates in diffuse ways to regulate the educational experience of learners with intellectual disability. The implications of this conception for inclusive education are briefly explored, and further areas for research are suggested.
- Full Text:
- Date Issued: 2012