Parasitism of Plutella xylostella (Lepidoptera, Plutellidae): field and laboratory observations
- Waladde, S M, Leutle, M F, Villet, Martin H
- Authors: Waladde, S M , Leutle, M F , Villet, Martin H
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442239 , vital:73969 , https://doi.org/10.1080/02571862.2001.10634397
- Description: Investigations carried out at Alice and its rural environs in the Eastern Cape province of South Africa, showed that parasitoids affecting the diamondback moth Plutella xylostella (L.) (Lepidoptera: Plutellidae) were Cotesia plutellae, Apanteles eriophyes, Diadegma sp., Diadromus collaris, Oomyzus sokolowskii and Hokeria sp. Cotesia plutellae was active all year round and accounted for 30–50% parasitism of P. xylostella. Field experiments using three cabbage cultivars, grown under pesticide-free conditions, indicated that C.plutellae achieved rates of parasitism as high as 90–95% for at least eight months of the year. In winter and early spring parasitism by C. plutellae was less than 30% in the field. This level of parasitism coincided with rising pest density resulting in a pest increase in early spring when C. plutellae appeared unable to control the high pest numbers. Towards the latter part of spring and early summer, C. plutellae parasitism and that of the other parasitoids increased. The possibility of using indigenous parasitoids especially C. plutellae in the management of P. xylostella in this area requires further investigation.
- Full Text:
- Date Issued: 2001
- Authors: Waladde, S M , Leutle, M F , Villet, Martin H
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442239 , vital:73969 , https://doi.org/10.1080/02571862.2001.10634397
- Description: Investigations carried out at Alice and its rural environs in the Eastern Cape province of South Africa, showed that parasitoids affecting the diamondback moth Plutella xylostella (L.) (Lepidoptera: Plutellidae) were Cotesia plutellae, Apanteles eriophyes, Diadegma sp., Diadromus collaris, Oomyzus sokolowskii and Hokeria sp. Cotesia plutellae was active all year round and accounted for 30–50% parasitism of P. xylostella. Field experiments using three cabbage cultivars, grown under pesticide-free conditions, indicated that C.plutellae achieved rates of parasitism as high as 90–95% for at least eight months of the year. In winter and early spring parasitism by C. plutellae was less than 30% in the field. This level of parasitism coincided with rising pest density resulting in a pest increase in early spring when C. plutellae appeared unable to control the high pest numbers. Towards the latter part of spring and early summer, C. plutellae parasitism and that of the other parasitoids increased. The possibility of using indigenous parasitoids especially C. plutellae in the management of P. xylostella in this area requires further investigation.
- Full Text:
- Date Issued: 2001
Photochemical studies of tetra-2, 3-pyridinoporphyrazines
- Seotsanyana-Mokhosi, Itumeleng, Kuznetsova, Nina, Nyokong, Tebello
- Authors: Seotsanyana-Mokhosi, Itumeleng , Kuznetsova, Nina , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291580 , vital:56889 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00427-0"
- Description: Tetra-2,3-pyridinoporphyrazines and the corresponding water-soluble N,N′,N′′,N′′′-tetramethyl-tetra-2,3-pyridinoporphyrazine complexes, containing central metal atoms; M=Ge, Sn, Si and Zn, were synthesized and their photochemical properties were investigated. The reductive quenching of pyridinoporphyrazines excited states, enhanced relative to phthalocyanines, was considered as the first photochemical step of dyes phototransformation in dimethylformamide (DMF) and dimethylsulfoxide (DMSO) solutions under irradiation with visible light. Efficiency of singlet oxygen photosensitization decreases significantly in the row phthalocyanines, unquaternized, quaternized tetra-2,3-pyridinoporphyrazine metallocomplexes.
- Full Text:
- Date Issued: 2001
- Authors: Seotsanyana-Mokhosi, Itumeleng , Kuznetsova, Nina , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291580 , vital:56889 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00427-0"
- Description: Tetra-2,3-pyridinoporphyrazines and the corresponding water-soluble N,N′,N′′,N′′′-tetramethyl-tetra-2,3-pyridinoporphyrazine complexes, containing central metal atoms; M=Ge, Sn, Si and Zn, were synthesized and their photochemical properties were investigated. The reductive quenching of pyridinoporphyrazines excited states, enhanced relative to phthalocyanines, was considered as the first photochemical step of dyes phototransformation in dimethylformamide (DMF) and dimethylsulfoxide (DMSO) solutions under irradiation with visible light. Efficiency of singlet oxygen photosensitization decreases significantly in the row phthalocyanines, unquaternized, quaternized tetra-2,3-pyridinoporphyrazine metallocomplexes.
- Full Text:
- Date Issued: 2001
Population structure of Apis mellifera scutellata (Hymenoptera: Apidae) filling the Uganda gap
- Radloff, Sarah E, Hepburn, H Randall
- Authors: Radloff, Sarah E , Hepburn, H Randall
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452017 , vital:75095 , https://hdl.handle.net/10520/EJC32956
- Description: Apis mellifera scutellata Lepeletier (Hymenoptera: Apidae) extends from South Africa to Ethiopia but includes local populations of varying morphology. The honeybees of Uganda previously represented an important biogeographical gap in defining the population structure of A. m. scutellata, but have now been resolved by morphometric analyses of worker honeybees analysed with multivariate techniques. Honeybees of lower altitudes (less than 2000 m) formed one distinct morphocluster typical of A. m. scutellata throughout the continent, while those at higher altitudes (less than 2000 m) formed a separate distinct cluster of large, dark bees. The latter occur as an archipelago of mountain ecotypes of A. m. scutellata..
- Full Text:
- Date Issued: 2001
- Authors: Radloff, Sarah E , Hepburn, H Randall
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452017 , vital:75095 , https://hdl.handle.net/10520/EJC32956
- Description: Apis mellifera scutellata Lepeletier (Hymenoptera: Apidae) extends from South Africa to Ethiopia but includes local populations of varying morphology. The honeybees of Uganda previously represented an important biogeographical gap in defining the population structure of A. m. scutellata, but have now been resolved by morphometric analyses of worker honeybees analysed with multivariate techniques. Honeybees of lower altitudes (less than 2000 m) formed one distinct morphocluster typical of A. m. scutellata throughout the continent, while those at higher altitudes (less than 2000 m) formed a separate distinct cluster of large, dark bees. The latter occur as an archipelago of mountain ecotypes of A. m. scutellata..
- Full Text:
- Date Issued: 2001
Population structure of Apis mellifera scutellata (Hymenoptera: Apidae) filling the Uganda gap
- Radloff, Sarah E, Hepburn, H Randall
- Authors: Radloff, Sarah E , Hepburn, H Randall
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452021 , vital:75096 , https://hdl.handle.net/10520/EJC32956
- Description: Apis mellifera scutellata Lepeletier (Hymenoptera: Apidae) extends from South Africa to Ethiopia but includes local populations of varying morphology. The honeybees of Uganda previously represented an important biogeographical gap in defining the population structure of A. m. scutellata, but have now been resolved by morphometric analyses of worker honeybees analysed with multivariate techniques. Honeybees of lower altitudes (less than 2000 m) formed one distinct morphocluster typical of A. m. scutellata throughout the continent, while those at higher altitudes (less than 2000 m) formed a separate distinct cluster of large, dark bees. The latter occur as an archipelago of mountain ecotypes of A. m. scutellata..
- Full Text:
- Date Issued: 2001
- Authors: Radloff, Sarah E , Hepburn, H Randall
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452021 , vital:75096 , https://hdl.handle.net/10520/EJC32956
- Description: Apis mellifera scutellata Lepeletier (Hymenoptera: Apidae) extends from South Africa to Ethiopia but includes local populations of varying morphology. The honeybees of Uganda previously represented an important biogeographical gap in defining the population structure of A. m. scutellata, but have now been resolved by morphometric analyses of worker honeybees analysed with multivariate techniques. Honeybees of lower altitudes (less than 2000 m) formed one distinct morphocluster typical of A. m. scutellata throughout the continent, while those at higher altitudes (less than 2000 m) formed a separate distinct cluster of large, dark bees. The latter occur as an archipelago of mountain ecotypes of A. m. scutellata..
- Full Text:
- Date Issued: 2001
Preliminary observations on the effects of hydrocortisone and sodium methohexital on development of Sarcophaga (Curranea) tibialis Macquart (Diptera: Sarcophagidae), and implications for estimating post mortem interval
- Musvasva, E, Williams, Kirstin A, Muller, Nikite W J, Villet, Martin H
- Authors: Musvasva, E , Williams, Kirstin A , Muller, Nikite W J , Villet, Martin H
- Date: 2001
- Language: English
- Type: text , Article
- Identifier: vital:7075 , http://hdl.handle.net/10962/d1009532
- Description: Larvae of Sarcophaga (Curranea) tibialis (S. tibialis) were reared at constant temperature on chicken liver treated with a steroid or a barbiturate at concentrations that would be lethal, half-lethal and twice-lethal doses for humans. Trends to greater mortality at higher drug concentrations were not statistically significant. Larvae exposed to either drug took significantly longer to reach pupation compared to those in the control, while larvae exposed to sodium methohexital passed through pupation significantly faster than those in the control. No systematic relationship was found between drug concentration and development time of larvae or pupae. The total developmental period from hatching to eclosion did not differ between treatments, implying that estimates of post mortem intervals- (PMI) based on the emergence of adult flies will not be affected by the involvement of these drugs in a case. On the other hand, anomalous pupation spans may indicate the presence of barbiturates. These findings are compared with patterns found in another fly fed other contaminants.
- Full Text:
- Date Issued: 2001
- Authors: Musvasva, E , Williams, Kirstin A , Muller, Nikite W J , Villet, Martin H
- Date: 2001
- Language: English
- Type: text , Article
- Identifier: vital:7075 , http://hdl.handle.net/10962/d1009532
- Description: Larvae of Sarcophaga (Curranea) tibialis (S. tibialis) were reared at constant temperature on chicken liver treated with a steroid or a barbiturate at concentrations that would be lethal, half-lethal and twice-lethal doses for humans. Trends to greater mortality at higher drug concentrations were not statistically significant. Larvae exposed to either drug took significantly longer to reach pupation compared to those in the control, while larvae exposed to sodium methohexital passed through pupation significantly faster than those in the control. No systematic relationship was found between drug concentration and development time of larvae or pupae. The total developmental period from hatching to eclosion did not differ between treatments, implying that estimates of post mortem intervals- (PMI) based on the emergence of adult flies will not be affected by the involvement of these drugs in a case. On the other hand, anomalous pupation spans may indicate the presence of barbiturates. These findings are compared with patterns found in another fly fed other contaminants.
- Full Text:
- Date Issued: 2001
Pseudocloeon cataractae (Crass)(Ephemeroptera: Baetidae): new combination and lectotype designation
- Lugo-Ortis, C R, de Moor, Ferdy C
- Authors: Lugo-Ortis, C R , de Moor, Ferdy C
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452189 , vital:75110 , https://hdl.handle.net/10520/EJC32950
- Description: Considerable clarification of taxonomic concepts and phylogenetic relationships within small minnow mayflies (Ephemeroptera: Baetidae) has resulted from recent studies involving Afro-tropical genera and species (Lugo-Ortiz and McCafferty 1996a, b, 1997a, b, 1998a-c; Barber-James and McCafferty 1997; McCafferty et al. 1997; Lugo-Ortiz et al. 1999; Lugo-Ortiz et al. 2001).
- Full Text:
- Date Issued: 2001
- Authors: Lugo-Ortis, C R , de Moor, Ferdy C
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452189 , vital:75110 , https://hdl.handle.net/10520/EJC32950
- Description: Considerable clarification of taxonomic concepts and phylogenetic relationships within small minnow mayflies (Ephemeroptera: Baetidae) has resulted from recent studies involving Afro-tropical genera and species (Lugo-Ortiz and McCafferty 1996a, b, 1997a, b, 1998a-c; Barber-James and McCafferty 1997; McCafferty et al. 1997; Lugo-Ortiz et al. 1999; Lugo-Ortiz et al. 2001).
- Full Text:
- Date Issued: 2001
Recruiters Guidelines
- COSATU
- Authors: COSATU
- Date: 2001
- Subjects: COSATU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/109753 , vital:33186
- Description: The purpose of this booklet is to touch in number of areas, which are important at this point for the recruitment campaign of the federation. It is not meant even by implication to provide details of how to handle the campaign what it does is to highlight issues and areas that we must think in the preparation for this campaign. More importantly is the fact that COSATU remains the biggest federation in South Africa and fastest growing international. Beside a loss of membership from + 2 million to + 1.8 million members. The decrease in membership is mostly because of retrenchments. The well known fact is that only about 40% of the workforce that is unionized. The aim of the recruitment drive is to access this 60% that is not unionized. The mistake must not be committed to think that the 40%, which is unionized, belong to COSATU. There are two other federations plus number of non-affiliated unions. Our commitment to One Country One Federation does not stop us to recruit from other unions as long as we remain under different bodies. This October campaign coincides with Red October campaign of the SACP and Health and Safety month of the federation this must be seen as strength than lack of co-ordination. One area that is link to recruitment is the servicing of membership. It is useless to recruit and fail to service membership because every campaign that we will take around recruitment we may find ourselves had to fight with disgruntled members and obviously it will be difficult to attract new members. This must say to us that members come first.
- Full Text:
- Date Issued: 2001
- Authors: COSATU
- Date: 2001
- Subjects: COSATU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/109753 , vital:33186
- Description: The purpose of this booklet is to touch in number of areas, which are important at this point for the recruitment campaign of the federation. It is not meant even by implication to provide details of how to handle the campaign what it does is to highlight issues and areas that we must think in the preparation for this campaign. More importantly is the fact that COSATU remains the biggest federation in South Africa and fastest growing international. Beside a loss of membership from + 2 million to + 1.8 million members. The decrease in membership is mostly because of retrenchments. The well known fact is that only about 40% of the workforce that is unionized. The aim of the recruitment drive is to access this 60% that is not unionized. The mistake must not be committed to think that the 40%, which is unionized, belong to COSATU. There are two other federations plus number of non-affiliated unions. Our commitment to One Country One Federation does not stop us to recruit from other unions as long as we remain under different bodies. This October campaign coincides with Red October campaign of the SACP and Health and Safety month of the federation this must be seen as strength than lack of co-ordination. One area that is link to recruitment is the servicing of membership. It is useless to recruit and fail to service membership because every campaign that we will take around recruitment we may find ourselves had to fight with disgruntled members and obviously it will be difficult to attract new members. This must say to us that members come first.
- Full Text:
- Date Issued: 2001
Recruiters Guidelines
- COSATU
- Authors: COSATU
- Date: 2001
- Subjects: COSATU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/137210 , vital:37498
- Description: The purpose of this booklet is to touch in number of areas, which are important at this point for the recruitment campaign of the federation. It is not meant even by implication to provide details of how to handle the campaign what it does is to highlight issues and areas that we must think in the preparation for this campaign. More importantly is the fact that COSATU remains the biggest federation in South Africa and fastest growing international. Beside a loss of membership from + 2 million to + 1.8 million members. The decrease in membership is mostly because of retrenchments. The well known fact is that only about 40% of the workforce that is unionized. The aim of the recruitment drive is to access this 60% that is not unionized. The mistake must not be committed to think that the 40%, which is unionized, belong to COSATU. There are two other federations plus number of non-affiliated unions. Our commitment to One Country One Federation does not stop us to recruit from other unions as long as we remain under different bodies. This October campaign coincides with Red October campaign of the SACP and Health and Safety month of the federation this must be seen as strength than lack of co-ordination. One area that is link to recruitment is the servicing of membership. It is useless to recruit and fail to service membership because every campaign that we will take around recruitment we may find ourselves had to fight with disgruntled members and obviously it will be difficult to attract new members. This must say to us that members come first.
- Full Text:
- Date Issued: 2001
- Authors: COSATU
- Date: 2001
- Subjects: COSATU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/137210 , vital:37498
- Description: The purpose of this booklet is to touch in number of areas, which are important at this point for the recruitment campaign of the federation. It is not meant even by implication to provide details of how to handle the campaign what it does is to highlight issues and areas that we must think in the preparation for this campaign. More importantly is the fact that COSATU remains the biggest federation in South Africa and fastest growing international. Beside a loss of membership from + 2 million to + 1.8 million members. The decrease in membership is mostly because of retrenchments. The well known fact is that only about 40% of the workforce that is unionized. The aim of the recruitment drive is to access this 60% that is not unionized. The mistake must not be committed to think that the 40%, which is unionized, belong to COSATU. There are two other federations plus number of non-affiliated unions. Our commitment to One Country One Federation does not stop us to recruit from other unions as long as we remain under different bodies. This October campaign coincides with Red October campaign of the SACP and Health and Safety month of the federation this must be seen as strength than lack of co-ordination. One area that is link to recruitment is the servicing of membership. It is useless to recruit and fail to service membership because every campaign that we will take around recruitment we may find ourselves had to fight with disgruntled members and obviously it will be difficult to attract new members. This must say to us that members come first.
- Full Text:
- Date Issued: 2001
Rendering Primitives for a Virtual Holodeck
- Morkel, Chantelle, Bangay, Shaun D
- Authors: Morkel, Chantelle , Bangay, Shaun D
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432795 , vital:72901 , https://www.cs.ru.ac.za/research/groups/vrsig/pastprojects/039virtualholodeck/paper02.pdf
- Description: The main objective of this research is to implement a “Star Trek”-like holodeck in a computer environment. An experiment to create graphical primitives and images solely out of spheres is being conducted. We investigate several approaches of creating primitives using spheres, and then using these primitives to create images. Initial results of this experiment are presented and we conclude that using spheres to create primitives and images is a viable approach to creating realistic-looking three-dimensional (3D) images.
- Full Text:
- Date Issued: 2001
- Authors: Morkel, Chantelle , Bangay, Shaun D
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432795 , vital:72901 , https://www.cs.ru.ac.za/research/groups/vrsig/pastprojects/039virtualholodeck/paper02.pdf
- Description: The main objective of this research is to implement a “Star Trek”-like holodeck in a computer environment. An experiment to create graphical primitives and images solely out of spheres is being conducted. We investigate several approaches of creating primitives using spheres, and then using these primitives to create images. Initial results of this experiment are presented and we conclude that using spheres to create primitives and images is a viable approach to creating realistic-looking three-dimensional (3D) images.
- Full Text:
- Date Issued: 2001
Research for health and life: life giving light
- Authors: Burnett, Mary
- Date: 2001
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7179 , http://hdl.handle.net/10962/d1006185 , Nyokong, Tebello
- Description: The elimination of certain cancers with light, known as photodynamic therapy, is a relatively new technique that has mainly been used in Russia, the USA and some parts of Europe, but with remarkable effectiveness. Professor Tebello Nyokong of the Department of Chemistry , at Rhodes University, Grahamstown, is collaborating with Professor David Phillips of the Imperial College, London, as part of the AtlantIC Alliance which also involves Emory University, Atlanta and the Georgia Institute of Technology, both in Atlanta, SA.
- Full Text:
- Date Issued: 2001
- Authors: Burnett, Mary
- Date: 2001
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7179 , http://hdl.handle.net/10962/d1006185 , Nyokong, Tebello
- Description: The elimination of certain cancers with light, known as photodynamic therapy, is a relatively new technique that has mainly been used in Russia, the USA and some parts of Europe, but with remarkable effectiveness. Professor Tebello Nyokong of the Department of Chemistry , at Rhodes University, Grahamstown, is collaborating with Professor David Phillips of the Imperial College, London, as part of the AtlantIC Alliance which also involves Emory University, Atlanta and the Georgia Institute of Technology, both in Atlanta, SA.
- Full Text:
- Date Issued: 2001
Revisiting nomenclature: 'Early Iron Age', 'First-Millennium Agriculturist', or what?
- Authors: Steele, John
- Date: 2001
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/11260/934 , vital:30067
- Description: As an art historian who has recently become fascinated by First-Millennium Agriculturist ceramics, I have come across several attempts at dealing with an issue of appropriate nomenclature for desigrrating this era. Conceptual frameworks are articulated using words, yet an apparent discomfort with the term Early Iron Age has seemingly not led to a consistently used altemative. I have been wondering about this and, with respect, offer my thoughts on the matter in a hope that debate will be furthered. Hereunder I utilise aspects of the KwaZulu-Natal and Eastem Cape first millennium ceramic sequence to address some significances associated with such artefacts in interpretations of the past, and then discuss some ways in which ideas of particular social contexts are embedded in language. Thereafter introduction of the term Iron Age into South African archaeology is referred to with reference to past and current usage, and advantages/disadvantages of alternatives are suggested.
- Full Text:
- Date Issued: 2001
- Authors: Steele, John
- Date: 2001
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/11260/934 , vital:30067
- Description: As an art historian who has recently become fascinated by First-Millennium Agriculturist ceramics, I have come across several attempts at dealing with an issue of appropriate nomenclature for desigrrating this era. Conceptual frameworks are articulated using words, yet an apparent discomfort with the term Early Iron Age has seemingly not led to a consistently used altemative. I have been wondering about this and, with respect, offer my thoughts on the matter in a hope that debate will be furthered. Hereunder I utilise aspects of the KwaZulu-Natal and Eastem Cape first millennium ceramic sequence to address some significances associated with such artefacts in interpretations of the past, and then discuss some ways in which ideas of particular social contexts are embedded in language. Thereafter introduction of the term Iron Age into South African archaeology is referred to with reference to past and current usage, and advantages/disadvantages of alternatives are suggested.
- Full Text:
- Date Issued: 2001
Rhodes University Graduation Ceremony 2001
- Authors: Rhodes University
- Date: 2001
- Language: English
- Type: text
- Identifier: vital:8146 , http://hdl.handle.net/10962/d1007296
- Description: Rhodes University Graduation Ceremonies 1820 Settlers National Monument Friday, 6 April 2001 at 10:30; 18:00 [and] Saturday, 7 April 2001 at 10:30 , Graduation Ceremony Christian Centre, Wyse Street, East London Friday, 1 May 2001 at 18:00
- Full Text:
- Date Issued: 2001
- Authors: Rhodes University
- Date: 2001
- Language: English
- Type: text
- Identifier: vital:8146 , http://hdl.handle.net/10962/d1007296
- Description: Rhodes University Graduation Ceremonies 1820 Settlers National Monument Friday, 6 April 2001 at 10:30; 18:00 [and] Saturday, 7 April 2001 at 10:30 , Graduation Ceremony Christian Centre, Wyse Street, East London Friday, 1 May 2001 at 18:00
- Full Text:
- Date Issued: 2001
SADTU draft input on WHITE PAPER No. 5 on early childhood development
- SADTU
- Authors: SADTU
- Date: 2001
- Subjects: SADTU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/176156 , vital:42665
- Description: SADTU welcomes the release of White Paper No. 5 on Early Childhood Development. We thank the Ministry and Department of Education for affording us this opportunity to make an input. We are however concerned that the process during its development excluded stakeholder participation.
- Full Text:
- Date Issued: 2001
- Authors: SADTU
- Date: 2001
- Subjects: SADTU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/176156 , vital:42665
- Description: SADTU welcomes the release of White Paper No. 5 on Early Childhood Development. We thank the Ministry and Department of Education for affording us this opportunity to make an input. We are however concerned that the process during its development excluded stakeholder participation.
- Full Text:
- Date Issued: 2001
Scales of mussel bed complexity: structure, associated biota and recruitment
- Lawrie, S M, McQuaid, Christopher D
- Authors: Lawrie, S M , McQuaid, Christopher D
- Date: 2001
- Language: English
- Type: text , Article
- Identifier: vital:6956 , http://hdl.handle.net/10962/d1011996
- Description: Hierarchically scaled surveys were carried out on beds of the brown mussel Perna perna (Linnaeus) on the South coast of South Africa. The object was to assess spatial and temporal variations in the complexity of mussel beds and to investigate relationships between mussel bed complexity and mussel recruitment. Complexity was divided into three components: physical complexity; demographic complexity; associated biota. A series of variables within each component were recorded at two different scales (10 and 50 cm) within nested quadrats on three separate occasions. The nested ANOVA design explicitly incorporated spatial scale as levels of the ANOVA. These scales were: shores (areas 1 km in length separated by 25 km); transects (areas 20 m in length separated by 100s of meters); 50×50-cm quadrats separated by meters and 10×10-cm quadrats separated by cm) This approach was intended to generate hypotheses concerning direct associations between recruitment and complexity versus co-variation due external processes. Three main questions were addressed: (1) At what scale does each variable of complexity exhibit greatest significant variation? (2) At these scales is there similar ranking of variables of complexity and recruitment? (3) Within this/these scales, is there any significant relationship between the variables measured and mussel recruitment? On two occasions (Nov. 97 and Mar. 98) the majority of variables showed greatest significant variation at the transect-scale. On a third occasion (Oct. 97) most variables showed greatest significant variation at the quadrat-scale and the site-scale. On all occasions a markedly high percentage of the variation encountered also occurred at the smallest scale of the study, i.e., the residual scale of the ANOVA analyses. Some similarity in the ranking of variables occurred at the transect scale. Within the transect-scale, there was little indication of any relationship between variables of complexity and recruitment. Relationships were inconsistent either among transects or among sampling occasions. Overall, the results suggest that a high degree of variation in mussel bed complexity consistently occurs at very small scales. High components of variance generally also occur at one or more larger scales; however, these scales vary with season. Mussel recruitment does not appear to be directly affected by complexity of mussel beds. Instead it appears external factors may influence both complexity and recruitment independently. In addition recruitment may influence complexity rather than vice versa.
- Full Text:
- Date Issued: 2001
- Authors: Lawrie, S M , McQuaid, Christopher D
- Date: 2001
- Language: English
- Type: text , Article
- Identifier: vital:6956 , http://hdl.handle.net/10962/d1011996
- Description: Hierarchically scaled surveys were carried out on beds of the brown mussel Perna perna (Linnaeus) on the South coast of South Africa. The object was to assess spatial and temporal variations in the complexity of mussel beds and to investigate relationships between mussel bed complexity and mussel recruitment. Complexity was divided into three components: physical complexity; demographic complexity; associated biota. A series of variables within each component were recorded at two different scales (10 and 50 cm) within nested quadrats on three separate occasions. The nested ANOVA design explicitly incorporated spatial scale as levels of the ANOVA. These scales were: shores (areas 1 km in length separated by 25 km); transects (areas 20 m in length separated by 100s of meters); 50×50-cm quadrats separated by meters and 10×10-cm quadrats separated by cm) This approach was intended to generate hypotheses concerning direct associations between recruitment and complexity versus co-variation due external processes. Three main questions were addressed: (1) At what scale does each variable of complexity exhibit greatest significant variation? (2) At these scales is there similar ranking of variables of complexity and recruitment? (3) Within this/these scales, is there any significant relationship between the variables measured and mussel recruitment? On two occasions (Nov. 97 and Mar. 98) the majority of variables showed greatest significant variation at the transect-scale. On a third occasion (Oct. 97) most variables showed greatest significant variation at the quadrat-scale and the site-scale. On all occasions a markedly high percentage of the variation encountered also occurred at the smallest scale of the study, i.e., the residual scale of the ANOVA analyses. Some similarity in the ranking of variables occurred at the transect scale. Within the transect-scale, there was little indication of any relationship between variables of complexity and recruitment. Relationships were inconsistent either among transects or among sampling occasions. Overall, the results suggest that a high degree of variation in mussel bed complexity consistently occurs at very small scales. High components of variance generally also occur at one or more larger scales; however, these scales vary with season. Mussel recruitment does not appear to be directly affected by complexity of mussel beds. Instead it appears external factors may influence both complexity and recruitment independently. In addition recruitment may influence complexity rather than vice versa.
- Full Text:
- Date Issued: 2001
Silicon octaphenoxyphthalocyanines
- Maree, M David, Kuznetsova, Nina, Nyokong, Tebello
- Authors: Maree, M David , Kuznetsova, Nina , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291591 , vital:56890 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00409-9"
- Description: Photochemical properties of series of axially substituted silicon octaphenoxyphthalocyanines with aryloxy, siloxy, aminoalkoxy, esters of carboxylic acids and sulphonic acid esters residues as axial ligands were studied in dimethylsulfoxide (DMSO) solution. It was found, that under Q-band excitation axial ligands in compounds studied have the propensity to be changed by hydroxyl groups with quantum yields in the range 10−5 to 10−2 depending on the nature of the axial ligand. Axial substituent phototransformation was followed by slow photobleaching of dihydroxysilicon octaphenoxyphthalocyanine (photoproduct) in self-sensitized singlet oxygen mediated oxidation of the macrocycle. Singlet oxygen quantum yields were found to be in the range 0.15–0.20 for majority of the phthalocyanines (Pc) studied.
- Full Text:
- Date Issued: 2001
- Authors: Maree, M David , Kuznetsova, Nina , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291591 , vital:56890 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00409-9"
- Description: Photochemical properties of series of axially substituted silicon octaphenoxyphthalocyanines with aryloxy, siloxy, aminoalkoxy, esters of carboxylic acids and sulphonic acid esters residues as axial ligands were studied in dimethylsulfoxide (DMSO) solution. It was found, that under Q-band excitation axial ligands in compounds studied have the propensity to be changed by hydroxyl groups with quantum yields in the range 10−5 to 10−2 depending on the nature of the axial ligand. Axial substituent phototransformation was followed by slow photobleaching of dihydroxysilicon octaphenoxyphthalocyanine (photoproduct) in self-sensitized singlet oxygen mediated oxidation of the macrocycle. Singlet oxygen quantum yields were found to be in the range 0.15–0.20 for majority of the phthalocyanines (Pc) studied.
- Full Text:
- Date Issued: 2001
Simultaneous voltammetric determination of dopamine and serotonin on carbon paste electrodes modified with iron (II) phthalocyanine complexes
- Oni, Joshua, Nyokong, Tebello
- Authors: Oni, Joshua , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291603 , vital:56891 , xlink:href="https://doi.org/10.1016/S0003-2670(01)00822-4"
- Description: Carbon paste electrodes (CPE) containing iron(II) phthalocyanine (FePc) and iron(II) tetrasulfophthalocyanine ([FeTSPc]4−) were used for the detection of dopamine (DA) and serotonin (5-HT). Both complexes showed catalytic activity towards the detection of DA and 5-HT. The catalytic activities of [FeTSPc]4− and FePc are compared with those of [CoTSPc]4−, [NiTSPc] 4−, CoPc and NiPc complexes and with those of metal(II) tetraaminophthalocyanines (MTAPc, where M=Ni, Co or Fe) complexes. A significant improvement in the reversibility of the DA oxidation couple was observed on [FeTSPc]4− and FePc modified CPE. [FeTSPc]4− and other [MTSPc]4− modified electrodes inhibited the detection of ascorbic acid (AA), a major interferent in the detection of DA. Simultaneous detection of DA and 5-HT on [FeTSPc]4− modified CPE, in the presence of AA, showed that AA does not interfere with the determination of both species. Also no interference between DA and 5-HT was observed.
- Full Text:
- Date Issued: 2001
- Authors: Oni, Joshua , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291603 , vital:56891 , xlink:href="https://doi.org/10.1016/S0003-2670(01)00822-4"
- Description: Carbon paste electrodes (CPE) containing iron(II) phthalocyanine (FePc) and iron(II) tetrasulfophthalocyanine ([FeTSPc]4−) were used for the detection of dopamine (DA) and serotonin (5-HT). Both complexes showed catalytic activity towards the detection of DA and 5-HT. The catalytic activities of [FeTSPc]4− and FePc are compared with those of [CoTSPc]4−, [NiTSPc] 4−, CoPc and NiPc complexes and with those of metal(II) tetraaminophthalocyanines (MTAPc, where M=Ni, Co or Fe) complexes. A significant improvement in the reversibility of the DA oxidation couple was observed on [FeTSPc]4− and FePc modified CPE. [FeTSPc]4− and other [MTSPc]4− modified electrodes inhibited the detection of ascorbic acid (AA), a major interferent in the detection of DA. Simultaneous detection of DA and 5-HT on [FeTSPc]4− modified CPE, in the presence of AA, showed that AA does not interfere with the determination of both species. Also no interference between DA and 5-HT was observed.
- Full Text:
- Date Issued: 2001
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
Solvent-free axial ligand substitution in octaphenoxyphthalocyaninato silicon complexes using microwave irradiation
- Maree, M David, Nyokong, Tebello
- Authors: Maree, M David , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/304830 , vital:58494 , xlink:href="https://journals.sagepub.com/doi/epdf/10.3184/030823401103168974"
- Description: Several axially substituted octaphenoxy silicon phthalocyanines were prepared by condensation of the complexes used as axial ligands with octaphenoxyphthalocyaninato (dichloro) silicon under microwave irradiation.
- Full Text:
- Date Issued: 2001
- Authors: Maree, M David , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/304830 , vital:58494 , xlink:href="https://journals.sagepub.com/doi/epdf/10.3184/030823401103168974"
- Description: Several axially substituted octaphenoxy silicon phthalocyanines were prepared by condensation of the complexes used as axial ligands with octaphenoxyphthalocyaninato (dichloro) silicon under microwave irradiation.
- Full Text:
- Date Issued: 2001
Spatial aspects of the reproductive and feeding biology of the striped robber, Brycinus lateralis (Pisces: Characidae), in the Okavango Delta, Botswana
- Booth, Anthony J, McKinlay, Bruce W
- Authors: Booth, Anthony J , McKinlay, Bruce W
- Date: 2001
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127020 , vital:35944 , https://doi.10.1080/15627020.2001.11657111
- Description: The Okavango Delta is a vast inland wetland system situated in northern Botswana. High rainfall is received in early summer in the southern Angolan highlands and throughout the Delta with the flood waters reaching the upper riverine floodplain between March and May where it percolates through to the lower drainage rivers between July and September. Aspects of the reproductive and feeding biology of two allopatric populations of the striped robber, Brycinus lateralis, a small characin species inhabiting the northern riverine floodplain and southern drainage rivers, were investigated. Both populations were similar in the biological aspects studied, with the flood cycle having little influence on the timing of reproduction, sexual maturity and dietary composition. Female fish from both populations matured sexually at 57mmSL, breeding over a protracted period during the warm, summer months. In both populations, the sex ratio was female-dominated at 4.8:1 (riverine floodplain) and 2.2:1 (drainage rivers). The striped robber is an opportunistic micro-carnivore with immature fish feeding predominantly on Daphnia spp. and adults being largely insectivorous.
- Full Text:
- Date Issued: 2001
- Authors: Booth, Anthony J , McKinlay, Bruce W
- Date: 2001
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127020 , vital:35944 , https://doi.10.1080/15627020.2001.11657111
- Description: The Okavango Delta is a vast inland wetland system situated in northern Botswana. High rainfall is received in early summer in the southern Angolan highlands and throughout the Delta with the flood waters reaching the upper riverine floodplain between March and May where it percolates through to the lower drainage rivers between July and September. Aspects of the reproductive and feeding biology of two allopatric populations of the striped robber, Brycinus lateralis, a small characin species inhabiting the northern riverine floodplain and southern drainage rivers, were investigated. Both populations were similar in the biological aspects studied, with the flood cycle having little influence on the timing of reproduction, sexual maturity and dietary composition. Female fish from both populations matured sexually at 57mmSL, breeding over a protracted period during the warm, summer months. In both populations, the sex ratio was female-dominated at 4.8:1 (riverine floodplain) and 2.2:1 (drainage rivers). The striped robber is an opportunistic micro-carnivore with immature fish feeding predominantly on Daphnia spp. and adults being largely insectivorous.
- Full Text:
- Date Issued: 2001
Spatial aspects of the reproductive and feeding biology of the striped robber, Brycinus lateralis (Pisces: Characidae), in the Okavango Delta, Botswana
- Booth, Anthony J, McKinlay, Bruce W
- Authors: Booth, Anthony J , McKinlay, Bruce W
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446838 , vital:74564 , https://doi.org/10.1080/15627020.2001.11657111
- Description: The Okavango Delta is a vast inland wetland system situated in northern Botswana. High rainfall is received in early summer in the southern Angolan highlands and throughout the Delta with the flood waters reaching the upper riverine floodplain between March and May where it percolates through to the lower drainage rivers between July and September. Aspects of the reproductive and feeding biology of two allopatric populations of the striped robber, Brycinus lateralis, a small characin species inhabiting the northern riverine floodplain and southern drainage rivers, were investigated. Both populations were similar in the biological aspects studied, with the flood cycle having little influence on the timing of reproduction, sexual maturity and dietary composition. Female fish from both populations matured sexually at 57 mm SL, breeding over a protracted period during the warm, summer months. In both populations, the sex ratio was female-dominated at 4.8:1 (riverine floodplain) and 2.2:1 (drainage rivers). The striped robber is an opportunistic micro-carnivore with immature fish feeding predominantly on Daphnia spp. and adults being largely insectivorous.
- Full Text:
- Date Issued: 2001
- Authors: Booth, Anthony J , McKinlay, Bruce W
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446838 , vital:74564 , https://doi.org/10.1080/15627020.2001.11657111
- Description: The Okavango Delta is a vast inland wetland system situated in northern Botswana. High rainfall is received in early summer in the southern Angolan highlands and throughout the Delta with the flood waters reaching the upper riverine floodplain between March and May where it percolates through to the lower drainage rivers between July and September. Aspects of the reproductive and feeding biology of two allopatric populations of the striped robber, Brycinus lateralis, a small characin species inhabiting the northern riverine floodplain and southern drainage rivers, were investigated. Both populations were similar in the biological aspects studied, with the flood cycle having little influence on the timing of reproduction, sexual maturity and dietary composition. Female fish from both populations matured sexually at 57 mm SL, breeding over a protracted period during the warm, summer months. In both populations, the sex ratio was female-dominated at 4.8:1 (riverine floodplain) and 2.2:1 (drainage rivers). The striped robber is an opportunistic micro-carnivore with immature fish feeding predominantly on Daphnia spp. and adults being largely insectivorous.
- Full Text:
- Date Issued: 2001