A new species of Buyisa Distant, 1907 (Hemiptera Cicadidae Cicadettinae Cicadettini) from South Africa
- Sanborn, Allen F, Villet, Martin H
- Authors: Sanborn, Allen F , Villet, Martin H
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441318 , vital:73877 , https://doi.org/10.4289/0013-8797.123.1.199
- Description: A new species of the cicada genus Buyisa Distant, 1907 is described from South Africa for an undetermined species referenced in the literature. Buyisa eccaensis new species is described and illustrated and notes on its biology are provided. A key to the officially described species of Buyisa is also included.
- Full Text:
- Date Issued: 2021
- Authors: Sanborn, Allen F , Villet, Martin H
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441318 , vital:73877 , https://doi.org/10.4289/0013-8797.123.1.199
- Description: A new species of the cicada genus Buyisa Distant, 1907 is described from South Africa for an undetermined species referenced in the literature. Buyisa eccaensis new species is described and illustrated and notes on its biology are provided. A key to the officially described species of Buyisa is also included.
- Full Text:
- Date Issued: 2021
A new species of red toad, Schismaderma Smith, 1849 (Anura: Bufonidae), from central Angola
- Baptista, Ninda L, Pinto, Pedro V, Keates, Chad, Edwards, Shelley, Rödel, Mark-Oliver, Conradie, Werner C
- Authors: Baptista, Ninda L , Pinto, Pedro V , Keates, Chad , Edwards, Shelley , Rödel, Mark-Oliver , Conradie, Werner C
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/461462 , vital:76204 , xlink:href="https://www.biotaxa.org/Zootaxa/article/view/zootaxa.5081.3.1"
- Description: A new species of red toad, from the previously monotypic genus Schismaderma, is described. The new species was found in Malanje Province, and seems endemic to central Angola, occurring approximately 500 km west of the closest known records of Schismaderma carens. Unusual adult colouration and geographical distance to remaining S. carens populations suggested specific differentiation. In an integrative approach, we compared the red toads from central Angola with S. carens from across the entire range, including molecular data, morphology of adults and tadpoles, and male advertisement calls. Phylogenetic analysis based on mitochondrial (12S, 16S, COI) and nuclear (CXCR4, RAG1) markers, retrieved the Angolan clade as monophyletic, and revealed intra-specific substructuring among the remaining Schismaderma. Genetic distances supported specific differentiation of the central Angolan material compared with other S. carens. Adults from the new Angolan species have bolder ventral patterning and smaller body size than S. carens. No obvious differences were detected between the tadpoles and the advertisement calls of the two Schismaderma species. This discovery adds to the knowledge of the herpetofauna of the Angolan Miombo woodlands, a poorly understood ecoregion, and likely more biodiverse than previously assumed. The result of past river basin dynamics in central Angola likely led to the evolution of this new species of Schismaderma.
- Full Text:
- Date Issued: 2021
- Authors: Baptista, Ninda L , Pinto, Pedro V , Keates, Chad , Edwards, Shelley , Rödel, Mark-Oliver , Conradie, Werner C
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/461462 , vital:76204 , xlink:href="https://www.biotaxa.org/Zootaxa/article/view/zootaxa.5081.3.1"
- Description: A new species of red toad, from the previously monotypic genus Schismaderma, is described. The new species was found in Malanje Province, and seems endemic to central Angola, occurring approximately 500 km west of the closest known records of Schismaderma carens. Unusual adult colouration and geographical distance to remaining S. carens populations suggested specific differentiation. In an integrative approach, we compared the red toads from central Angola with S. carens from across the entire range, including molecular data, morphology of adults and tadpoles, and male advertisement calls. Phylogenetic analysis based on mitochondrial (12S, 16S, COI) and nuclear (CXCR4, RAG1) markers, retrieved the Angolan clade as monophyletic, and revealed intra-specific substructuring among the remaining Schismaderma. Genetic distances supported specific differentiation of the central Angolan material compared with other S. carens. Adults from the new Angolan species have bolder ventral patterning and smaller body size than S. carens. No obvious differences were detected between the tadpoles and the advertisement calls of the two Schismaderma species. This discovery adds to the knowledge of the herpetofauna of the Angolan Miombo woodlands, a poorly understood ecoregion, and likely more biodiverse than previously assumed. The result of past river basin dynamics in central Angola likely led to the evolution of this new species of Schismaderma.
- Full Text:
- Date Issued: 2021
A note on mapping propolis deposits in Cape honey bee (Apis mellifera capensis) colonies
- Ellis, James D, Hepburn, H Randall
- Authors: Ellis, James D , Hepburn, H Randall
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451805 , vital:75078 , https://hdl.handle.net/10520/EJC32532
- Description: Propolis is a mixture of plant-derived substances, and sometimes wax, collected by most Apis mellifera subspecies for use as caulking and entrance-reducing material and as a colony sealant and sterilant (Ruttner 1988; Schmidt and Buchmann 1992; Hepburn and Radloff 1998). Additionally, it is used in honey bee defense against colony invaders, particularly Aethina tumida Murray (small hive beetles) (Hepburn and Radloff 1998; Neumann et al. 2001; Ellis 2002).
- Full Text:
- Date Issued: 2003
- Authors: Ellis, James D , Hepburn, H Randall
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451805 , vital:75078 , https://hdl.handle.net/10520/EJC32532
- Description: Propolis is a mixture of plant-derived substances, and sometimes wax, collected by most Apis mellifera subspecies for use as caulking and entrance-reducing material and as a colony sealant and sterilant (Ruttner 1988; Schmidt and Buchmann 1992; Hepburn and Radloff 1998). Additionally, it is used in honey bee defense against colony invaders, particularly Aethina tumida Murray (small hive beetles) (Hepburn and Radloff 1998; Neumann et al. 2001; Ellis 2002).
- Full Text:
- Date Issued: 2003
A Note on the (Continued) Ability of the Yield Curve to Forecast Economic Downturns in South Africa
- Botha, Ferdi, Keeton, Gavin R
- Authors: Botha, Ferdi , Keeton, Gavin R
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/395994 , vital:69142 , xlink:href="https://doi.org/10.1111/saje.12053"
- Description: In 2002-2003, the South African yield spread falsely signalled a downswing that never materialised. This paper provides two reasons for this false signal. First, while the Reserve Bank never actually officially declared the start of a downswing, by alternative measures a downswing did actually occur. It is this severe weakness in economic activity at that time that the yield curve pointed to. Second, short-term interest rates in 2003 were higher than they should have been because of a mistake made in measuring consumer price inflation. Because South Africa had recently introduced an inflation-targeting regime, policy interest rates were, as a result of this error, kept too high for too long. This policy mistake was rectified as soon as the error in the Consumer Price Index was discovered. Thus, the yield curve in 2003 pointed to the reality that short-term interest rates were too high and risked pushing the economy into full blown recession. This is demonstrated by the fact that it was a fall in long bond interest rates that caused the yield spread to turn negative, indicating expectations that short-term interest rates would need to be cut – as indeed they were.
- Full Text:
- Date Issued: 2014
- Authors: Botha, Ferdi , Keeton, Gavin R
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/395994 , vital:69142 , xlink:href="https://doi.org/10.1111/saje.12053"
- Description: In 2002-2003, the South African yield spread falsely signalled a downswing that never materialised. This paper provides two reasons for this false signal. First, while the Reserve Bank never actually officially declared the start of a downswing, by alternative measures a downswing did actually occur. It is this severe weakness in economic activity at that time that the yield curve pointed to. Second, short-term interest rates in 2003 were higher than they should have been because of a mistake made in measuring consumer price inflation. Because South Africa had recently introduced an inflation-targeting regime, policy interest rates were, as a result of this error, kept too high for too long. This policy mistake was rectified as soon as the error in the Consumer Price Index was discovered. Thus, the yield curve in 2003 pointed to the reality that short-term interest rates were too high and risked pushing the economy into full blown recession. This is demonstrated by the fact that it was a fall in long bond interest rates that caused the yield spread to turn negative, indicating expectations that short-term interest rates would need to be cut – as indeed they were.
- Full Text:
- Date Issued: 2014
A novel axially palladium (II)-Schiff base complex substituted silicon (IV) phthalocyanine
- Sen, Pinar, Nyokong, Tebello
- Authors: Sen, Pinar , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186813 , vital:44536 , xlink:href="https://doi.org/10.1016/j.poly.2019.114135"
- Description: In this study, a novel silicon(IV) phthalocyanine is reported for the first time as a phthalocyanine derivative bearing axially a palladium(II)-Schiff base complex. The photophysical and photochemical properties of the new Si(IV)Pc, such as absorption, fluorescence, singlet oxygen quantum yields, triplet state quantum yields and exited state lifetimes were measured in DMSO. The new silicon phthalocyanine displayed very low fluorescence, showing efficient intersystem crossing resulting in high triplet and high singlet oxygen quantum yields in DMSO. When compared with the unsubstituted SiPcCl2, the singlet oxygen quantum yield value (UD = 0.47) in relation to the triplet quantum yield (UT = 0.82), which is an important determinant for PDT applications, increased. The photodynamic antimicrobial chemotherapy activity (PACT) of new Si(IV)Pc towards Staphylococcus aureus was determined in comparison to the unsubstituted SiPcCl2. The results of the photodynamic antimicrobial effect study demonstrated that the Pd(II) complex substituted SiPc (5) possesses excellent photodynamic activity with a reduction percentage value of 99.94% and a log red value of 3.26.
- Full Text:
- Date Issued: 2019
- Authors: Sen, Pinar , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186813 , vital:44536 , xlink:href="https://doi.org/10.1016/j.poly.2019.114135"
- Description: In this study, a novel silicon(IV) phthalocyanine is reported for the first time as a phthalocyanine derivative bearing axially a palladium(II)-Schiff base complex. The photophysical and photochemical properties of the new Si(IV)Pc, such as absorption, fluorescence, singlet oxygen quantum yields, triplet state quantum yields and exited state lifetimes were measured in DMSO. The new silicon phthalocyanine displayed very low fluorescence, showing efficient intersystem crossing resulting in high triplet and high singlet oxygen quantum yields in DMSO. When compared with the unsubstituted SiPcCl2, the singlet oxygen quantum yield value (UD = 0.47) in relation to the triplet quantum yield (UT = 0.82), which is an important determinant for PDT applications, increased. The photodynamic antimicrobial chemotherapy activity (PACT) of new Si(IV)Pc towards Staphylococcus aureus was determined in comparison to the unsubstituted SiPcCl2. The results of the photodynamic antimicrobial effect study demonstrated that the Pd(II) complex substituted SiPc (5) possesses excellent photodynamic activity with a reduction percentage value of 99.94% and a log red value of 3.26.
- Full Text:
- Date Issued: 2019
A novel dimeric exoglucanase (GH5_38)
- Mafa, Mpho S, Dirr, Heinrich W, Malgas, Samkelo, Krause, Rui W M, Pletschke, Brett I
- Authors: Mafa, Mpho S , Dirr, Heinrich W , Malgas, Samkelo , Krause, Rui W M , Pletschke, Brett I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193976 , vital:45412 , xlink:href="https://doi.org/10.3390/molecules25030746"
- Description: An exoglucanase (Exg-D) from the glycoside hydrolase family 5 subfamily 38 (GH5_38) was heterologously expressed and structurally and biochemically characterised at a molecular level for its application in alkyl glycoside synthesis. The purified Exg-D existed in both dimeric and monomeric forms in solution, which showed highest activity on mixed-linked β-glucan (88.0 and 86.7 U/mg protein, respectively) and lichenin (24.5 and 23.7 U/mg protein, respectively). They displayed a broad optimum pH range from 5.5 to 7 and a temperature optimum from 40 to 60 °C. Kinetic studies demonstrated that Exg-D had a higher affinity towards β-glucan, with a Km of 7.9 mg/mL and a kcat of 117.2 s−1, compared to lichenin which had a Km of 21.5 mg/mL and a kcat of 70.0 s−1. The circular dichroism profile of Exg-D showed that its secondary structure consisted of 11% α-helices, 36% β-strands and 53% coils. Exg-D performed transglycosylation using p-nitrophenyl cellobioside as a glycosyl donor and several primary alcohols as acceptors to produce methyl-, ethyl- and propyl-cellobiosides. These products were identified and quantified via thin-layer chromatography (TLC) and liquid chromatography–mass spectrometry (LC-MS). We concluded that Exg-D is a novel and promising oligomeric glycoside hydrolase for the one-step synthesis of alkyl glycosides with more than one monosaccharide unit.
- Full Text:
- Date Issued: 2020
- Authors: Mafa, Mpho S , Dirr, Heinrich W , Malgas, Samkelo , Krause, Rui W M , Pletschke, Brett I
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193976 , vital:45412 , xlink:href="https://doi.org/10.3390/molecules25030746"
- Description: An exoglucanase (Exg-D) from the glycoside hydrolase family 5 subfamily 38 (GH5_38) was heterologously expressed and structurally and biochemically characterised at a molecular level for its application in alkyl glycoside synthesis. The purified Exg-D existed in both dimeric and monomeric forms in solution, which showed highest activity on mixed-linked β-glucan (88.0 and 86.7 U/mg protein, respectively) and lichenin (24.5 and 23.7 U/mg protein, respectively). They displayed a broad optimum pH range from 5.5 to 7 and a temperature optimum from 40 to 60 °C. Kinetic studies demonstrated that Exg-D had a higher affinity towards β-glucan, with a Km of 7.9 mg/mL and a kcat of 117.2 s−1, compared to lichenin which had a Km of 21.5 mg/mL and a kcat of 70.0 s−1. The circular dichroism profile of Exg-D showed that its secondary structure consisted of 11% α-helices, 36% β-strands and 53% coils. Exg-D performed transglycosylation using p-nitrophenyl cellobioside as a glycosyl donor and several primary alcohols as acceptors to produce methyl-, ethyl- and propyl-cellobiosides. These products were identified and quantified via thin-layer chromatography (TLC) and liquid chromatography–mass spectrometry (LC-MS). We concluded that Exg-D is a novel and promising oligomeric glycoside hydrolase for the one-step synthesis of alkyl glycosides with more than one monosaccharide unit.
- Full Text:
- Date Issued: 2020
A novel gold (I)-mediated intramolecular transamidation of benzoyl thiourea derivatives to form benzamides via dethiocyanation
- Odame, Felix, Woodcock, Guillaume, Hosten, Eric C, Lobb, Kevin A, Tshentu, Zenixole R
- Authors: Odame, Felix , Woodcock, Guillaume , Hosten, Eric C , Lobb, Kevin A , Tshentu, Zenixole R
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446988 , vital:74575 , xlink:href="https://doi.org/10.1016/j.jorganchem.2020.121359"
- Description: A novel gold(I)-mediated intramolecular transamidation of thiourea derivatives to yield benzamides via dethiocyanation have been achieved by the reaction of 3-(1,3-benzothiazol-2-yl)-1-(benzoyl)thiourea derivatives in the presence of gold(I) precursors. The compounds have been characterized using IR, NMR, GC-MS and microanalysis. The single crystal XRD of 3-(1,3-benzothiazol-2-yl)-1-(3-bromobenzoyl)thiourea (5), 3-(1,3-benzothiazol-2-yl)-1-(3-methoxybenzoyl)thiourea (6), N-(benzothiazol-2-yl)benzamide (10), N-(benzothiazol-2-yl)-3-chlorobenzamide (11), N-(benzothiazol-2-yl)-4-nitrobenzamide (12), N-(benzothiazol-2-yl)-3-bromobenzamide (14) have been discussed. The novel transformation is thought to proceed by a gold(I)-mediated intramolecular transamidation reaction which releases thiocyanate to yield the benzamide. Density functional theory calculations have been used to support the proposed mechanism for this transformation.
- Full Text:
- Date Issued: 2020
- Authors: Odame, Felix , Woodcock, Guillaume , Hosten, Eric C , Lobb, Kevin A , Tshentu, Zenixole R
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446988 , vital:74575 , xlink:href="https://doi.org/10.1016/j.jorganchem.2020.121359"
- Description: A novel gold(I)-mediated intramolecular transamidation of thiourea derivatives to yield benzamides via dethiocyanation have been achieved by the reaction of 3-(1,3-benzothiazol-2-yl)-1-(benzoyl)thiourea derivatives in the presence of gold(I) precursors. The compounds have been characterized using IR, NMR, GC-MS and microanalysis. The single crystal XRD of 3-(1,3-benzothiazol-2-yl)-1-(3-bromobenzoyl)thiourea (5), 3-(1,3-benzothiazol-2-yl)-1-(3-methoxybenzoyl)thiourea (6), N-(benzothiazol-2-yl)benzamide (10), N-(benzothiazol-2-yl)-3-chlorobenzamide (11), N-(benzothiazol-2-yl)-4-nitrobenzamide (12), N-(benzothiazol-2-yl)-3-bromobenzamide (14) have been discussed. The novel transformation is thought to proceed by a gold(I)-mediated intramolecular transamidation reaction which releases thiocyanate to yield the benzamide. Density functional theory calculations have been used to support the proposed mechanism for this transformation.
- Full Text:
- Date Issued: 2020
A PCA-based modelling technique for predicting environmental suitability for organisms from presence records
- Robertson, Mark P, Caithness, N, Villet, Martin H
- Authors: Robertson, Mark P , Caithness, N , Villet, Martin H
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442609 , vital:74014 , https://doi.org/10.1046/j.1472-4642.2001.00094.x
- Description: We present a correlative modelling technique that uses locality records (associated with species presence) and a set of predictor variables to produce a statistically justifiable probability response surface for a target species. The probability response surface indicates the suitability of each grid cell in a map for the target species in terms of the suite of predictor variables. The technique constructs a hyperspace for the target species using principal component axes derived from a principal components analysis performed on a training dataset. The training dataset comprises the values of the predictor variables associated with the localities where the species has been recorded as present. The origin of this hyperspace is taken to characterize the centre of the niche of the organism. All the localities (grid‐cells) in the map region are then fitted into this hyperspace using the values of the predictor variables at these localities (the prediction dataset). The Euclidean distance from any locality to the origin of the hyperspace gives a measure of the ‘centrality’ of that locality in the hyperspace. These distances are used to derive probability values for each grid cell in the map region. The modelling technique was applied to bioclimatic data to predict bioclimatic suitability for three alien invasive plant species (Lantana camara L., Ricinus communis L. and Solanum mauritianum Scop.) in South Africa, Lesotho and Swaziland. The models were tested against independent test records by calculating area under the curve (AUC) values of receiver operator characteristic (ROC) curves and kappa statistics. There was good agreement between the models and the independent test records. The pre‐processing of climatic variable data to reduce the deleterious effects of multicollinearity, and the use of stopping rules to prevent overfitting of the models are important aspects of the modelling process.
- Full Text:
- Date Issued: 2001
- Authors: Robertson, Mark P , Caithness, N , Villet, Martin H
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442609 , vital:74014 , https://doi.org/10.1046/j.1472-4642.2001.00094.x
- Description: We present a correlative modelling technique that uses locality records (associated with species presence) and a set of predictor variables to produce a statistically justifiable probability response surface for a target species. The probability response surface indicates the suitability of each grid cell in a map for the target species in terms of the suite of predictor variables. The technique constructs a hyperspace for the target species using principal component axes derived from a principal components analysis performed on a training dataset. The training dataset comprises the values of the predictor variables associated with the localities where the species has been recorded as present. The origin of this hyperspace is taken to characterize the centre of the niche of the organism. All the localities (grid‐cells) in the map region are then fitted into this hyperspace using the values of the predictor variables at these localities (the prediction dataset). The Euclidean distance from any locality to the origin of the hyperspace gives a measure of the ‘centrality’ of that locality in the hyperspace. These distances are used to derive probability values for each grid cell in the map region. The modelling technique was applied to bioclimatic data to predict bioclimatic suitability for three alien invasive plant species (Lantana camara L., Ricinus communis L. and Solanum mauritianum Scop.) in South Africa, Lesotho and Swaziland. The models were tested against independent test records by calculating area under the curve (AUC) values of receiver operator characteristic (ROC) curves and kappa statistics. There was good agreement between the models and the independent test records. The pre‐processing of climatic variable data to reduce the deleterious effects of multicollinearity, and the use of stopping rules to prevent overfitting of the models are important aspects of the modelling process.
- Full Text:
- Date Issued: 2001
A peaceful revenge: Achieving structural and agential transformation in a South African context using cognitive justice and emancipatory social learning
- Authors: Burt, Jane C , James, Anna
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392049 , vital:68717 , xlink:href="https://doi.org/10.1080/14767430.2018.1550312"
- Description: This is an account of the emancipatory struggle that faces agents who seek to change the oppressive social structures associated with neo-liberalism. We begin by ‘digging amongst the bones’ of the calls for resistance that have been declared dead or assimilated/co-opted by neoliberal theorists. This leads us to unearth, then utilize, Paulo Freire’s Pedagogy of the Oppressed, Steve Biko’s Black Consciousness and Shiv Visvanathan's ideas; which are examples of Roy Bhaskar’s transformative dialectic. We argue, using examples, that cognitive justice – a concept common to each of our chosen theorists – is vital in enabling emancipatory social learning. By embracing cognitive justice, the agents gained confidence, which led to their increased ability to champion community and non-academic knowledge. It also uncovered structural tensions – attendant in neoliberalism – around privilege. By articulating these tensions, the participants were able to ‘come closer together’. Such processes, initiated by ensuring cognitive justice, are possible steps in achieving universal solidarity; which is likely to be a necessary step along the path of achieving emancipation.
- Full Text:
- Date Issued: 2018
- Authors: Burt, Jane C , James, Anna
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392049 , vital:68717 , xlink:href="https://doi.org/10.1080/14767430.2018.1550312"
- Description: This is an account of the emancipatory struggle that faces agents who seek to change the oppressive social structures associated with neo-liberalism. We begin by ‘digging amongst the bones’ of the calls for resistance that have been declared dead or assimilated/co-opted by neoliberal theorists. This leads us to unearth, then utilize, Paulo Freire’s Pedagogy of the Oppressed, Steve Biko’s Black Consciousness and Shiv Visvanathan's ideas; which are examples of Roy Bhaskar’s transformative dialectic. We argue, using examples, that cognitive justice – a concept common to each of our chosen theorists – is vital in enabling emancipatory social learning. By embracing cognitive justice, the agents gained confidence, which led to their increased ability to champion community and non-academic knowledge. It also uncovered structural tensions – attendant in neoliberalism – around privilege. By articulating these tensions, the participants were able to ‘come closer together’. Such processes, initiated by ensuring cognitive justice, are possible steps in achieving universal solidarity; which is likely to be a necessary step along the path of achieving emancipation.
- Full Text:
- Date Issued: 2018
A perfect end: A study of syllable codas in South African Sign Language
- Köhlo, Mikhaela D.K., Siebörger, Ian, Bennett, William G
- Authors: Köhlo, Mikhaela D.K. , Siebörger, Ian , Bennett, William G
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/385295 , vital:68005 , xlink:href="https://www.ajol.info/index.php/splp/article/view/156629"
- Description: South African Sign Language (SASL) is an understudied language with a rich and interesting phonology. For instance, while the language allows onsetless syllables, it does not allow codaless syllables, except in a small class of signs which do not include path movement. This article identifies and defines possible constraints on syllable codas in SASL. Using a video dictionary as data, we have coded handshapes at locations occurring at the onset and coda of the more common signs in the lexicon. In handshape, it has been found that the selected fingers may move to create different handshapes in the coda position, but that these coda handshapes are often [1], [5], [A], [Å] or [S], which are the unmarked handshapes of the non-dominant hand in asymmetrical two-handed signs (Sandler and Lillo-Martin 2006). Furthermore, the joint specification for the selected fingers can also vary in the coda position, but there appear to be strict limitations on which joint combinations are permitted in the onset-coda relationship. There are also constraints on coda location. The major body region can change within a single syllable, and the preferred body regions in the coda position are [body] and [H2]. It is evident not only that handshape and location constraints occur at the coda position, but that these constraints show patterns similar to coda neutralisation in many spoken languages.
- Full Text:
- Date Issued: 2017
- Authors: Köhlo, Mikhaela D.K. , Siebörger, Ian , Bennett, William G
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/385295 , vital:68005 , xlink:href="https://www.ajol.info/index.php/splp/article/view/156629"
- Description: South African Sign Language (SASL) is an understudied language with a rich and interesting phonology. For instance, while the language allows onsetless syllables, it does not allow codaless syllables, except in a small class of signs which do not include path movement. This article identifies and defines possible constraints on syllable codas in SASL. Using a video dictionary as data, we have coded handshapes at locations occurring at the onset and coda of the more common signs in the lexicon. In handshape, it has been found that the selected fingers may move to create different handshapes in the coda position, but that these coda handshapes are often [1], [5], [A], [Å] or [S], which are the unmarked handshapes of the non-dominant hand in asymmetrical two-handed signs (Sandler and Lillo-Martin 2006). Furthermore, the joint specification for the selected fingers can also vary in the coda position, but there appear to be strict limitations on which joint combinations are permitted in the onset-coda relationship. There are also constraints on coda location. The major body region can change within a single syllable, and the preferred body regions in the coda position are [body] and [H2]. It is evident not only that handshape and location constraints occur at the coda position, but that these constraints show patterns similar to coda neutralisation in many spoken languages.
- Full Text:
- Date Issued: 2017
A Pied Starling study
- Authors: Craig, Adrian J F K
- Date: 1983
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465256 , vital:76587
- Description: After some years of ringing bishop birds Euplectes sp. and other weavers at reed beds in the western Cape and Natal, a move to Grahamstown seemed a good time to change birds. So I decided look at the Pied Starling Spreo bicolor, one of those conmon birds about which we know almost nothing.
- Full Text:
- Date Issued: 1983
- Authors: Craig, Adrian J F K
- Date: 1983
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465256 , vital:76587
- Description: After some years of ringing bishop birds Euplectes sp. and other weavers at reed beds in the western Cape and Natal, a move to Grahamstown seemed a good time to change birds. So I decided look at the Pied Starling Spreo bicolor, one of those conmon birds about which we know almost nothing.
- Full Text:
- Date Issued: 1983
A plan for African music
- Authors: Tracey, Hugh T
- Date: 1965
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/481480 , vital:78556 , https://doi.org/10.21504/amj.v3i4.1059
- Description: There are so many kinds of music in Africa that, as usual, it is advisable first to define one’s terms. For the purpose of this paper, the music under discussion is the compositions of indigenous, sub-Saharan, African people, and without recognisable foreign influences. This music shows the same integrity, logic, sensibility and originality as their own languages. Like their languages, a single variety of music-making may be found only within a limited area, but taken together, the different varieties are found to share certain common characteristics which justify their inclusion under the title of “African music”. All of them are contemporary, continually evolving, well founded in past practice, clearly understood and performed by everyone in each local group, though rarely by outsiders. Unfortunately, African music does not yet share the great advantage already enjoyed by African languages of being relatively easy to write down on paper, and to read back again once it has been written down. Here is the missing link between authentic African music and formal educational practice.
- Full Text:
- Date Issued: 1965
- Authors: Tracey, Hugh T
- Date: 1965
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/481480 , vital:78556 , https://doi.org/10.21504/amj.v3i4.1059
- Description: There are so many kinds of music in Africa that, as usual, it is advisable first to define one’s terms. For the purpose of this paper, the music under discussion is the compositions of indigenous, sub-Saharan, African people, and without recognisable foreign influences. This music shows the same integrity, logic, sensibility and originality as their own languages. Like their languages, a single variety of music-making may be found only within a limited area, but taken together, the different varieties are found to share certain common characteristics which justify their inclusion under the title of “African music”. All of them are contemporary, continually evolving, well founded in past practice, clearly understood and performed by everyone in each local group, though rarely by outsiders. Unfortunately, African music does not yet share the great advantage already enjoyed by African languages of being relatively easy to write down on paper, and to read back again once it has been written down. Here is the missing link between authentic African music and formal educational practice.
- Full Text:
- Date Issued: 1965
A population genetics study of Pale-winged Starlings, Onychognathus nabouroup, using novel microsatellite markers
- Munshi, Naadhira, Symes, Craig, Maayer, Pieter de, Craig, Adrian J F K, Henry, Laurence, Hausberger, Martine, Mollett, Jean
- Authors: Munshi, Naadhira , Symes, Craig , Maayer, Pieter de , Craig, Adrian J F K , Henry, Laurence , Hausberger, Martine , Mollett, Jean
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448718 , vital:74754 , https://www.ajol.info/index.php/scopus/article/view/211291
- Description: Recent research into starling species has revealed the existence of vocal social markers and a link between song temporal structuring and social organisation. The aim of the present study was to develop a genetic tool for understanding the population structuring and behaviour (social/parental transmission) and mating in Pale-winged Starlings (Onychognathus nabouroup), a songbird which is found in arid areas of southern Africa. Using next-generation sequencing, microsatellite markers comprising six dinucleotides, eighteen trinucleotides and twenty-four tetra-nucleotides specific to the Pale-winged Starling were isolated and developed. A total of 77 birds were sampled from the Augrabies Falls Nature Reserve in South Africa (n= 53) and the Ai Ais-Richtersveld Transfrontier Park resort in Namibia (n= 24), respectively. Fifteen polymorphic microsatellite markers were genotyped. The statistical programme STRUCTURE revealed four different genetic clusters within the two populations.
- Full Text:
- Date Issued: 2021
- Authors: Munshi, Naadhira , Symes, Craig , Maayer, Pieter de , Craig, Adrian J F K , Henry, Laurence , Hausberger, Martine , Mollett, Jean
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448718 , vital:74754 , https://www.ajol.info/index.php/scopus/article/view/211291
- Description: Recent research into starling species has revealed the existence of vocal social markers and a link between song temporal structuring and social organisation. The aim of the present study was to develop a genetic tool for understanding the population structuring and behaviour (social/parental transmission) and mating in Pale-winged Starlings (Onychognathus nabouroup), a songbird which is found in arid areas of southern Africa. Using next-generation sequencing, microsatellite markers comprising six dinucleotides, eighteen trinucleotides and twenty-four tetra-nucleotides specific to the Pale-winged Starling were isolated and developed. A total of 77 birds were sampled from the Augrabies Falls Nature Reserve in South Africa (n= 53) and the Ai Ais-Richtersveld Transfrontier Park resort in Namibia (n= 24), respectively. Fifteen polymorphic microsatellite markers were genotyped. The statistical programme STRUCTURE revealed four different genetic clusters within the two populations.
- Full Text:
- Date Issued: 2021
A Practical Use for AI-Generated Images
- Boby, Alden, Brown, Dane L, Connan, James
- Authors: Boby, Alden , Brown, Dane L , Connan, James
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/463345 , vital:76401 , xlink:href="https://link.springer.com/chapter/10.1007/978-3-031-43838-7_12"
- Description: Collecting data for research can be costly and time-consuming, and available methods to speed up the process are limited. This research paper compares real data and AI-generated images for training an object detection model. The study aimed to assess how the utilisation of AI-generated images influences the performance of an object detection model. The study used a popular object detection model, YOLO, and trained it on a dataset with real car images as well as a synthetic dataset generated with a state-of-the-art diffusion model. The results showed that while the model trained on real data performed better on real-world images, the model trained on AI-generated images, in some cases, showed improved performance on certain images and was good enough to function as a licence plate detector on its own. The study highlights the potential of using AI-generated images for data augmentation in object detection models and sheds light on the trade-off between real and synthetic data in the training process. The findings of this study can inform future research in object detection and help practitioners make informed decisions when choosing between real and synthetic data for training object detection models.
- Full Text:
- Date Issued: 2023
- Authors: Boby, Alden , Brown, Dane L , Connan, James
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/463345 , vital:76401 , xlink:href="https://link.springer.com/chapter/10.1007/978-3-031-43838-7_12"
- Description: Collecting data for research can be costly and time-consuming, and available methods to speed up the process are limited. This research paper compares real data and AI-generated images for training an object detection model. The study aimed to assess how the utilisation of AI-generated images influences the performance of an object detection model. The study used a popular object detection model, YOLO, and trained it on a dataset with real car images as well as a synthetic dataset generated with a state-of-the-art diffusion model. The results showed that while the model trained on real data performed better on real-world images, the model trained on AI-generated images, in some cases, showed improved performance on certain images and was good enough to function as a licence plate detector on its own. The study highlights the potential of using AI-generated images for data augmentation in object detection models and sheds light on the trade-off between real and synthetic data in the training process. The findings of this study can inform future research in object detection and help practitioners make informed decisions when choosing between real and synthetic data for training object detection models.
- Full Text:
- Date Issued: 2023
A prayer for Joy
- Authors: Mann, Chris
- Date: 1977
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/459533 , vital:75840 , https://journals.co.za/doi/epdf/10.10520/AJA00284459_356
- Description: New Coin is one of South Africa's most established and influential poetry journals. It publishes poetry, and poetry-related reviews, commentary and interviews. New Coin places a particular emphasis on evolving forms and experimental use of the English language in poetry in the South African context. In this sense it has traced the most exciting trends and currents in contemporary poetry in South Africa for a decade of more. The journal is published twice a year in June and December by the Institute for the Study of English in Africa (ISEA), Rhodes University.
- Full Text:
- Date Issued: 1977
- Authors: Mann, Chris
- Date: 1977
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/459533 , vital:75840 , https://journals.co.za/doi/epdf/10.10520/AJA00284459_356
- Description: New Coin is one of South Africa's most established and influential poetry journals. It publishes poetry, and poetry-related reviews, commentary and interviews. New Coin places a particular emphasis on evolving forms and experimental use of the English language in poetry in the South African context. In this sense it has traced the most exciting trends and currents in contemporary poetry in South Africa for a decade of more. The journal is published twice a year in June and December by the Institute for the Study of English in Africa (ISEA), Rhodes University.
- Full Text:
- Date Issued: 1977
A prayer for my countrymen
- Authors: Butler, Guy F
- Date: 1965
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/458771 , vital:75770 , https://journals.co.za/doi/epdf/10.10520/AJA00284459_102
- Description: New Coin is one of South Africa's most established and influential poetry journals. It publishes poetry, and poetry-related reviews, commentary and interviews. New Coin places a particular emphasis on evolving forms and experimental use of the English language in poetry in the South African context. In this sense it has traced the most exciting trends and currents in contemporary poetry in South Africa for a decade of more. The journal is published twice a year in June and December by the Institute for the Study of English in Africa (ISEA), Rhodes University.
- Full Text:
- Date Issued: 1965
- Authors: Butler, Guy F
- Date: 1965
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/458771 , vital:75770 , https://journals.co.za/doi/epdf/10.10520/AJA00284459_102
- Description: New Coin is one of South Africa's most established and influential poetry journals. It publishes poetry, and poetry-related reviews, commentary and interviews. New Coin places a particular emphasis on evolving forms and experimental use of the English language in poetry in the South African context. In this sense it has traced the most exciting trends and currents in contemporary poetry in South Africa for a decade of more. The journal is published twice a year in June and December by the Institute for the Study of English in Africa (ISEA), Rhodes University.
- Full Text:
- Date Issued: 1965
A pre-impoundment study of the Sabie-Sand River system, Mpumalanga with special reference to predicted impacts on the Kruger National Park (Volume 3)
- O’Keeffe, Jay H, Weeks, D C, Fourie, A, Davies, B R
- Authors: O’Keeffe, Jay H , Weeks, D C , Fourie, A , Davies, B R
- Date: 1996
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/437759 , vital:73407 , ISBN 1 86845 237 9 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/294-3-96.pdf
- Description: This project was begun in January 1990 in response to a need to characterise the fauna of the Sabie-Sand River system for which plans were already advanced to build impoundments. During the cource of the project, the region was subjected to the worst drought on record. As a result the scope and duration of the project was extended. This volume is the first of three which describe the results. Volume 1 de-scribes the ecological status of the Sabie, the Sand and other major tributaries of the system, including the diversity and distribution of the fish and macro-invertebrate faunas, and their habitat requirements. The second volume describes the results of a drought monitoring programme in which three reaches of the Sabie and one in the Sand River were intensively sampled throughout the worst drought on record, from 1991 to 1992. The purpose of this volume is to assess the probable effects of proposed impoundments in the Sabie-Sand River (both positive and nega-tive) on the ecology of the downstream reaches, and to draw on the information from volumes one and two to make recommendations for the management and monitoring of the flows in the river.
- Full Text:
- Date Issued: 1996
- Authors: O’Keeffe, Jay H , Weeks, D C , Fourie, A , Davies, B R
- Date: 1996
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/437759 , vital:73407 , ISBN 1 86845 237 9 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/294-3-96.pdf
- Description: This project was begun in January 1990 in response to a need to characterise the fauna of the Sabie-Sand River system for which plans were already advanced to build impoundments. During the cource of the project, the region was subjected to the worst drought on record. As a result the scope and duration of the project was extended. This volume is the first of three which describe the results. Volume 1 de-scribes the ecological status of the Sabie, the Sand and other major tributaries of the system, including the diversity and distribution of the fish and macro-invertebrate faunas, and their habitat requirements. The second volume describes the results of a drought monitoring programme in which three reaches of the Sabie and one in the Sand River were intensively sampled throughout the worst drought on record, from 1991 to 1992. The purpose of this volume is to assess the probable effects of proposed impoundments in the Sabie-Sand River (both positive and nega-tive) on the ecology of the downstream reaches, and to draw on the information from volumes one and two to make recommendations for the management and monitoring of the flows in the river.
- Full Text:
- Date Issued: 1996
A preliminary study of minimal-contention locks
- Machanick, Philip, Mbiyavanga, Mamana
- Authors: Machanick, Philip , Mbiyavanga, Mamana
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439093 , vital:73544 , https://doi.org/10.1145/3278681.3278713
- Description: As multicore CPUs become more common, scalable synchronization primitives have wider use and ideas previously used in large-scale computation are worth re-opening for wider use. In this paper I explore one approach to scalable synchronization, a minimal-contention lock (M-lock). The key idea is to avoid spinning on a global variable but instead for each blocked task (process or thread) to spin on a local lock representing the task that immediately preceded it in attempting to acquire the lock. This creates an ordering based on the order in which tasks attempt to acquire the lock, preventing starvation. The only globally shared variable is a pointer to the next local lock to be contended for. Each contending task swaps the value of this pointer for a pointer to its own variable. It spins on the variable previously pointed to by the global pointer. Each waiting task spins on a lock only seen by itself and the owner of that lock variable. While a task is spinning, the lock variable can be held in its local cache until invalidated by the lock owner when it unsets the lock. Consequently, the amount of bus traffic is considerably less than with a spinlock, which has the pernicious feature that the task releasing the lock is delayed by all the other bus traffic arising from contention for the lock. An MCS lock has similar properties but is more complicated and requires more memory contention-causing operations. This paper outlines the design of the M-lock and provides a preliminary performance analysis.
- Full Text:
- Date Issued: 2018
- Authors: Machanick, Philip , Mbiyavanga, Mamana
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439093 , vital:73544 , https://doi.org/10.1145/3278681.3278713
- Description: As multicore CPUs become more common, scalable synchronization primitives have wider use and ideas previously used in large-scale computation are worth re-opening for wider use. In this paper I explore one approach to scalable synchronization, a minimal-contention lock (M-lock). The key idea is to avoid spinning on a global variable but instead for each blocked task (process or thread) to spin on a local lock representing the task that immediately preceded it in attempting to acquire the lock. This creates an ordering based on the order in which tasks attempt to acquire the lock, preventing starvation. The only globally shared variable is a pointer to the next local lock to be contended for. Each contending task swaps the value of this pointer for a pointer to its own variable. It spins on the variable previously pointed to by the global pointer. Each waiting task spins on a lock only seen by itself and the owner of that lock variable. While a task is spinning, the lock variable can be held in its local cache until invalidated by the lock owner when it unsets the lock. Consequently, the amount of bus traffic is considerably less than with a spinlock, which has the pernicious feature that the task releasing the lock is delayed by all the other bus traffic arising from contention for the lock. An MCS lock has similar properties but is more complicated and requires more memory contention-causing operations. This paper outlines the design of the M-lock and provides a preliminary performance analysis.
- Full Text:
- Date Issued: 2018
A probabilistic movement model for shortest path formation in virtual ant-like agents
- Chibaya, Colin, Bangay, Shaun D
- Authors: Chibaya, Colin , Bangay, Shaun D
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433125 , vital:72945 , https://doi.org/10.1145/1292491.1292493
- Description: We propose a probabilistic movement model for controlling ant-like agents foraging between two points. Such agents are all identical, simple, autonomous and can only communicate indirectly through the environment. These agents secrete two types of pheromone, one to mark trails towards the goal and another to mark trails back to the starting point. Three pheromone perception strategies are proposed (Strategy A, B and C). Agents that use strategy A perceive the desirability of a neighbouring location as the difference between levels of attractive and repulsive pheromone in that location. With strategy B, agents perceive the desirability of a location as the quotient of levels of attractive and repulsive pheromone. Agents using strategy C determine the product of the levels of attractive pheromone with the complement of levels of repulsive pheromone. We conduct experiments to confirm directionality as emergent property of trails formed by agents that use each strategy. In addition, we compare path formation speed and the quality of the formed path under changes in the environment. We also investigate each strategy's robustness in environments that contain obstacles. Finally, we investigate how adaptive each strategy is when obstacles are eventually removed from the scene and find that the best strategy of these three is strategy A. Such a strategy provides useful guidelines to researchers in further applications of swarm intelligence metaphors for complex problem solving.
- Full Text:
- Date Issued: 2007
- Authors: Chibaya, Colin , Bangay, Shaun D
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433125 , vital:72945 , https://doi.org/10.1145/1292491.1292493
- Description: We propose a probabilistic movement model for controlling ant-like agents foraging between two points. Such agents are all identical, simple, autonomous and can only communicate indirectly through the environment. These agents secrete two types of pheromone, one to mark trails towards the goal and another to mark trails back to the starting point. Three pheromone perception strategies are proposed (Strategy A, B and C). Agents that use strategy A perceive the desirability of a neighbouring location as the difference between levels of attractive and repulsive pheromone in that location. With strategy B, agents perceive the desirability of a location as the quotient of levels of attractive and repulsive pheromone. Agents using strategy C determine the product of the levels of attractive pheromone with the complement of levels of repulsive pheromone. We conduct experiments to confirm directionality as emergent property of trails formed by agents that use each strategy. In addition, we compare path formation speed and the quality of the formed path under changes in the environment. We also investigate each strategy's robustness in environments that contain obstacles. Finally, we investigate how adaptive each strategy is when obstacles are eventually removed from the scene and find that the best strategy of these three is strategy A. Such a strategy provides useful guidelines to researchers in further applications of swarm intelligence metaphors for complex problem solving.
- Full Text:
- Date Issued: 2007
A production function for cricket: the South African perspective
- Brock, Kelcey, Fraser, Gavin C G, Botha, Ferdi
- Authors: Brock, Kelcey , Fraser, Gavin C G , Botha, Ferdi
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396007 , vital:69143 , xlink:href="https://hdl.handle.net/10520/EJC124240"
- Description: Production functions are common to any productive activity. Although it may not appear obvious, cricket is no different. Production functions in cricket provide a wide range of information, utilised to enhance efficiency and maximize match success. Given these benefits, this study involved the derivation of a production function for the South African SuperSport Series and an analysis of technical efficiency. An econometric analysis was conducted on data from the 2004-2011 cricket seasons and it was concluded that the most optimal strategy for South African teams involved a combination of attacking batting and defensive bowling. Furthermore, South African teams had a relatively low variable substitutability and a high degree of technical efficiency.
- Full Text:
- Date Issued: 2012
- Authors: Brock, Kelcey , Fraser, Gavin C G , Botha, Ferdi
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396007 , vital:69143 , xlink:href="https://hdl.handle.net/10520/EJC124240"
- Description: Production functions are common to any productive activity. Although it may not appear obvious, cricket is no different. Production functions in cricket provide a wide range of information, utilised to enhance efficiency and maximize match success. Given these benefits, this study involved the derivation of a production function for the South African SuperSport Series and an analysis of technical efficiency. An econometric analysis was conducted on data from the 2004-2011 cricket seasons and it was concluded that the most optimal strategy for South African teams involved a combination of attacking batting and defensive bowling. Furthermore, South African teams had a relatively low variable substitutability and a high degree of technical efficiency.
- Full Text:
- Date Issued: 2012