Late Quaternary climatic changes, and associated human responses, during the last ~ 45 000 years in the Eastern and adjoining Western Cape, South Africa
- Authors: Lewis, Colin A
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6700 , http://hdl.handle.net/10962/d1006736
- Description: Palaeoenvironmental evidence indicative of former climatic conditions in the Eastern and adjoining Western Cape during the last ~ 45 000 yr is presented and summarised. Interstadial conditions began before 43 000 BP but were succeeded by stadial conditions at ~ 24 000 BP. These climatic phases are designated the Birnam Interstadial and the Bottelnek Stadial after the type sites at which they were identified in the Eastern Cape. The Bottelnek Stadial apparently equates with the Last Glacial Maximum. Late Glacial warming was apparent by 18/17 000 BP. Sea level rose markedly by ~ 14 000 BP. Climatic oscillations marked the end of the Late Glacial. The Early Holocene was drier than the Late Holocene and, at least in the Drakensberg, there was marked aridity in the mid-Holocene. Human responses to these climatic events are briefly described.
- Full Text:
- Date Issued: 2008
- Authors: Lewis, Colin A
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6700 , http://hdl.handle.net/10962/d1006736
- Description: Palaeoenvironmental evidence indicative of former climatic conditions in the Eastern and adjoining Western Cape during the last ~ 45 000 yr is presented and summarised. Interstadial conditions began before 43 000 BP but were succeeded by stadial conditions at ~ 24 000 BP. These climatic phases are designated the Birnam Interstadial and the Bottelnek Stadial after the type sites at which they were identified in the Eastern Cape. The Bottelnek Stadial apparently equates with the Last Glacial Maximum. Late Glacial warming was apparent by 18/17 000 BP. Sea level rose markedly by ~ 14 000 BP. Climatic oscillations marked the end of the Late Glacial. The Early Holocene was drier than the Late Holocene and, at least in the Drakensberg, there was marked aridity in the mid-Holocene. Human responses to these climatic events are briefly described.
- Full Text:
- Date Issued: 2008
Lattice-valued convergence spaces and regularity
- Authors: Jäger, Gunter
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:6826 , http://hdl.handle.net/10962/d1012336
- Description: We define a regularity axiom for lattice-valued convergence spaces where the lattice is a complete Heyting algebra. To this end, we generalize the characterization of regularity by a ”dual form” of a diagonal condition. We show that our axiom ensures that a regular T1-space is separated and that regularity is preserved under initial constructions. Further we present an extension theorem for a continuous mapping from a subspace to a regular space. A characterization in the restricted case that the lattice is a complete Boolean algebra in terms of the closure of an L-filter is given.
- Full Text:
- Date Issued: 2008
- Authors: Jäger, Gunter
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:6826 , http://hdl.handle.net/10962/d1012336
- Description: We define a regularity axiom for lattice-valued convergence spaces where the lattice is a complete Heyting algebra. To this end, we generalize the characterization of regularity by a ”dual form” of a diagonal condition. We show that our axiom ensures that a regular T1-space is separated and that regularity is preserved under initial constructions. Further we present an extension theorem for a continuous mapping from a subspace to a regular space. A characterization in the restricted case that the lattice is a complete Boolean algebra in terms of the closure of an L-filter is given.
- Full Text:
- Date Issued: 2008
Lessons from aloes in the Thicket Biome: reconstructing past elephant browsing to understand the present
- Parker, Daniel M, Bernard, Ric T F
- Authors: Parker, Daniel M , Bernard, Ric T F
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6894 , http://hdl.handle.net/10962/d1011654
- Description: It is very difficult to quantify elephant-induced change to vegetation in the absence of adequate historical benchmarks. In this commentary, we explore the historical distribution of aloes in the Thicket Biome of South Africa. We contend that the large stands of aesthetically pleasing aloes in the Thicket Biome can be likened to the even-aged stands of tall trees in the riparian forests of Botswana, both being artefacts of the loss of large herbivores through disease and hunting in the past. Elephant browsing on aloes may therefore be the first step in the vegetation reverting to a situation similar to the one prior to excessive hunting in the region.
- Full Text:
- Date Issued: 2008
- Authors: Parker, Daniel M , Bernard, Ric T F
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6894 , http://hdl.handle.net/10962/d1011654
- Description: It is very difficult to quantify elephant-induced change to vegetation in the absence of adequate historical benchmarks. In this commentary, we explore the historical distribution of aloes in the Thicket Biome of South Africa. We contend that the large stands of aesthetically pleasing aloes in the Thicket Biome can be likened to the even-aged stands of tall trees in the riparian forests of Botswana, both being artefacts of the loss of large herbivores through disease and hunting in the past. Elephant browsing on aloes may therefore be the first step in the vegetation reverting to a situation similar to the one prior to excessive hunting in the region.
- Full Text:
- Date Issued: 2008
Marginalisation and demographic change in the semi-arid Karoo, South Africa
- Nel, Etienne L, Hill, Trevor R
- Authors: Nel, Etienne L , Hill, Trevor R
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6719 , http://hdl.handle.net/10962/d1006792
- Description: Semi-arid areas are often considered to be environmentally and economically marginal, a situation which has been exacerbated by economic change, shifts in agricultural production and land use, and changing state policy. These themes are explored with reference to a semi-arid landscape, namely the Karoo, which covers some 40% of the geographic space of South Africa and is used primarily for extensive livestock farming. Despite long-term decline in agricultural output, the traditional mainstay of the region, and weakening small town economies, the Karoo's population and the economies of its largest service centres are growing. There are, real socio-economic needs and development backlogs, and the situation has been exacerbated by recent political marginalisation. In this study, the small towns of the region are focal points of investigation and provide a lens to investigate the changing demographic and economic dynamics of the Karoo. Most of the region's population lives in these centres which are service, collection, and distribution points for what traditionally has been an agriculture-based regional economy. This paper explores the concept of marginalisation with specific reference to historical, economic, and demographic change.
- Full Text:
- Date Issued: 2008
- Authors: Nel, Etienne L , Hill, Trevor R
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6719 , http://hdl.handle.net/10962/d1006792
- Description: Semi-arid areas are often considered to be environmentally and economically marginal, a situation which has been exacerbated by economic change, shifts in agricultural production and land use, and changing state policy. These themes are explored with reference to a semi-arid landscape, namely the Karoo, which covers some 40% of the geographic space of South Africa and is used primarily for extensive livestock farming. Despite long-term decline in agricultural output, the traditional mainstay of the region, and weakening small town economies, the Karoo's population and the economies of its largest service centres are growing. There are, real socio-economic needs and development backlogs, and the situation has been exacerbated by recent political marginalisation. In this study, the small towns of the region are focal points of investigation and provide a lens to investigate the changing demographic and economic dynamics of the Karoo. Most of the region's population lives in these centres which are service, collection, and distribution points for what traditionally has been an agriculture-based regional economy. This paper explores the concept of marginalisation with specific reference to historical, economic, and demographic change.
- Full Text:
- Date Issued: 2008
Marine reservoir corrections : St. Helena, South Atlantic Ocean
- Lewis, Colin A, Reimer, P J, Reimer, R W
- Authors: Lewis, Colin A , Reimer, P J , Reimer, R W
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6701 , http://hdl.handle.net/10962/d1006737
- Description: We present the first marine reservoir age and ∆R determination for the island of St. Helena using marine mollusk radiocarbon dates obtained from an historical context of known age. This represents the first marine reservoir age and ∆R determination in the southern Atlantic Ocean within thousands of kilometers of the island. The depletion of 14C in the shells indicates a rather larger reservoir age for that portion of the surface Atlantic than models indicate. The implication is that upwelling old water along the Namibian coast is transported for a considerable distance, although it is likely to be variable on a decadal timescale. An artilleryman’s button, together with other artifacts found in a midden, demonstrate association of the mollusk shells with a narrow historic period of AD 1815–1835.
- Full Text:
- Date Issued: 2008
- Authors: Lewis, Colin A , Reimer, P J , Reimer, R W
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6701 , http://hdl.handle.net/10962/d1006737
- Description: We present the first marine reservoir age and ∆R determination for the island of St. Helena using marine mollusk radiocarbon dates obtained from an historical context of known age. This represents the first marine reservoir age and ∆R determination in the southern Atlantic Ocean within thousands of kilometers of the island. The depletion of 14C in the shells indicates a rather larger reservoir age for that portion of the surface Atlantic than models indicate. The implication is that upwelling old water along the Namibian coast is transported for a considerable distance, although it is likely to be variable on a decadal timescale. An artilleryman’s button, together with other artifacts found in a midden, demonstrate association of the mollusk shells with a narrow historic period of AD 1815–1835.
- Full Text:
- Date Issued: 2008
Nuclear translocation of the phosphoprotein Hop (Hsp70/Hsp90 organizing protein) occurs under heat shock, and its proposed nuclear localization signal is involved in Hsp90 binding
- Daniel, Sheril, Bradley, Graeme, Longshaw, Victoria M, Söti, Csaba, Csermely, Peter, Blatch, Gregory L
- Authors: Daniel, Sheril , Bradley, Graeme , Longshaw, Victoria M , Söti, Csaba , Csermely, Peter , Blatch, Gregory L
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6472 , http://hdl.handle.net/10962/d1005951 , http://dx.doi.org/10.1016/j.bbamcr.2008.01.014
- Description: The Hsp70–Hsp90 complex is implicated in the folding and regulation of numerous signaling proteins, and Hop, the Hsp70–Hsp90 Organizing Protein, facilitates the association of this multichaperone machinery. Phosphatase treatment of mouse cell extracts reduced the number of Hop isoforms compared to untreated extracts, providing the first direct evidence that Hop was phosphorylated in vivo. Furthermore, surface plasmon resonance (SPR) spectroscopy showed that a cdc2 kinase phosphorylation mimic of Hop had reduced affinity for Hsp90 binding. Hop was predominantly cytoplasmic, but translocated to the nucleus in response to heat shock. A putative bipartite nuclear localization signal (NLS) has been identified within the Hsp90-binding domain of Hop. Although substitution of residues within the major arm of this proposed NLS abolished Hop–Hsp90 interaction as determined by SPR, this was not sufficient to prevent the nuclear accumulation of Hop under leptomycin-B treatment and heat shock conditions. These results showed for the first time that the subcellular localization of Hop was stress regulated and that the major arm of the putative NLS was not directly important for nuclear translocation but was critical for Hop–Hsp90 association in vitro. We propose a model in which the association of Hop with Hsp90 and the phosphorylated status of Hop both play a role in the mechanism of nucleo-cytoplasmic shuttling of Hop.
- Full Text:
- Date Issued: 2008
- Authors: Daniel, Sheril , Bradley, Graeme , Longshaw, Victoria M , Söti, Csaba , Csermely, Peter , Blatch, Gregory L
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6472 , http://hdl.handle.net/10962/d1005951 , http://dx.doi.org/10.1016/j.bbamcr.2008.01.014
- Description: The Hsp70–Hsp90 complex is implicated in the folding and regulation of numerous signaling proteins, and Hop, the Hsp70–Hsp90 Organizing Protein, facilitates the association of this multichaperone machinery. Phosphatase treatment of mouse cell extracts reduced the number of Hop isoforms compared to untreated extracts, providing the first direct evidence that Hop was phosphorylated in vivo. Furthermore, surface plasmon resonance (SPR) spectroscopy showed that a cdc2 kinase phosphorylation mimic of Hop had reduced affinity for Hsp90 binding. Hop was predominantly cytoplasmic, but translocated to the nucleus in response to heat shock. A putative bipartite nuclear localization signal (NLS) has been identified within the Hsp90-binding domain of Hop. Although substitution of residues within the major arm of this proposed NLS abolished Hop–Hsp90 interaction as determined by SPR, this was not sufficient to prevent the nuclear accumulation of Hop under leptomycin-B treatment and heat shock conditions. These results showed for the first time that the subcellular localization of Hop was stress regulated and that the major arm of the putative NLS was not directly important for nuclear translocation but was critical for Hop–Hsp90 association in vitro. We propose a model in which the association of Hop with Hsp90 and the phosphorylated status of Hop both play a role in the mechanism of nucleo-cytoplasmic shuttling of Hop.
- Full Text:
- Date Issued: 2008
Oceanic dispersal barriers, adaptation and larval retention: an interdisciplinary assessment of potential factors maintaining a phylogeographic break between sister lineages of an African prawn
- Teske, Peter R, Papadopoulos, Isabelle, Newman, Brent K, Dworschak, Peter C, McQuaid, Christopher D, Barker, Nigel P
- Authors: Teske, Peter R , Papadopoulos, Isabelle , Newman, Brent K , Dworschak, Peter C , McQuaid, Christopher D , Barker, Nigel P
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6546 , http://hdl.handle.net/10962/d1006002 , http://dx.doi.org/10.1186/1471-2148-8-341
- Description: Background. Genetic breaks separating regional lineages of marine organisms with potentially high broadcasting abilities are generally attributed either to dispersal barriers such as currents or upwelling, or to behavioural strategies promoting self-recruitment. We investigated whether such patterns could potentially also be explained by adaptations to different environmental conditions by studying two morphologically distinguishable genetic lineages of the estuarine mudprawn Upogebia africana across a biogeographic disjunction in south-eastern Africa. The study area encompasses a transition between temperate and subtropical biotas, where the warm, southward-flowing Agulhas Current is deflected away from the coast, and its inshore edge is characterised by intermittent upwelling. To determine how this phylogeographic break is maintained, we estimated gene flow among populations in the region, tested for isolation by distance as an indication of larval retention, and reared larvae of the temperate and subtropical lineages at a range of different temperatures. Results. Of four populations sampled, the two northernmost exclusively included the subtropical lineage, a central population had a mixture of both lineages, and the southernmost estuary had only haplotypes of the temperate lineage. No evidence was found for isolation by distance, and gene flow was bidirectional and of similar magnitude among adjacent populations. In both lineages, the optimum temperature for larval development was at about 23°C, but a clear difference was found at lower temperatures. While larvae of the temperate lineage could complete development at temperatures as low as 12°C, those of the subtropical lineage did not complete development below 17°C. Conclusion. The results indicate that both southward dispersal of the subtropical lineage inshore of the Agulhas Current, and its establishment in the temperate province, may be limited primarily by low water temperatures. There is no evidence that the larvae of the temperate lineage would survive less well in the subtropical province than in their native habitat, and their exclusion from this region may be due to a combination of upwelling, short larval duration with limited dispersal potential near the coast, plus transport away from the coast of larvae that become entrained in the Agulhas Current. This study shows how methods from different fields of research (genetics, physiology, oceanography and morphology) can be combined to study phylogeographic patterns.
- Full Text:
- Date Issued: 2008
- Authors: Teske, Peter R , Papadopoulos, Isabelle , Newman, Brent K , Dworschak, Peter C , McQuaid, Christopher D , Barker, Nigel P
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6546 , http://hdl.handle.net/10962/d1006002 , http://dx.doi.org/10.1186/1471-2148-8-341
- Description: Background. Genetic breaks separating regional lineages of marine organisms with potentially high broadcasting abilities are generally attributed either to dispersal barriers such as currents or upwelling, or to behavioural strategies promoting self-recruitment. We investigated whether such patterns could potentially also be explained by adaptations to different environmental conditions by studying two morphologically distinguishable genetic lineages of the estuarine mudprawn Upogebia africana across a biogeographic disjunction in south-eastern Africa. The study area encompasses a transition between temperate and subtropical biotas, where the warm, southward-flowing Agulhas Current is deflected away from the coast, and its inshore edge is characterised by intermittent upwelling. To determine how this phylogeographic break is maintained, we estimated gene flow among populations in the region, tested for isolation by distance as an indication of larval retention, and reared larvae of the temperate and subtropical lineages at a range of different temperatures. Results. Of four populations sampled, the two northernmost exclusively included the subtropical lineage, a central population had a mixture of both lineages, and the southernmost estuary had only haplotypes of the temperate lineage. No evidence was found for isolation by distance, and gene flow was bidirectional and of similar magnitude among adjacent populations. In both lineages, the optimum temperature for larval development was at about 23°C, but a clear difference was found at lower temperatures. While larvae of the temperate lineage could complete development at temperatures as low as 12°C, those of the subtropical lineage did not complete development below 17°C. Conclusion. The results indicate that both southward dispersal of the subtropical lineage inshore of the Agulhas Current, and its establishment in the temperate province, may be limited primarily by low water temperatures. There is no evidence that the larvae of the temperate lineage would survive less well in the subtropical province than in their native habitat, and their exclusion from this region may be due to a combination of upwelling, short larval duration with limited dispersal potential near the coast, plus transport away from the coast of larvae that become entrained in the Agulhas Current. This study shows how methods from different fields of research (genetics, physiology, oceanography and morphology) can be combined to study phylogeographic patterns.
- Full Text:
- Date Issued: 2008
Optimisation of Bacillus thuringiensis var. israelensis (Vectobac®) applications for the blackfly control programme on the Orange River, South Africa
- Rivers-Moore, Nick A, Bangay, Shaun D, Palmer, R W
- Authors: Rivers-Moore, Nick A , Bangay, Shaun D , Palmer, R W
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:7090 , http://hdl.handle.net/10962/d1012421
- Description: The Orange River, South Africa's largest river, is a critical water resource for the country. In spite of the clear economic benefits of regulating river flows through a series of impoundments, one of the significant undesirable ecological consequences of this regulation has been the regular outbreaks of the pest blackfly species Simulium chutteri and S. damnosum s.l. (Diptera: Simuliidae). The current control programme, carried out by the South African National Department of Agriculture, uses regular applications, by helicopter, of the target-specific bacterial larvicide Bacillus thuringiensis var. israelensis. While cost-benefit analyses show significant benefits to the control programme, benefits could potentially be further increased through applying smaller volumes of larvicide in an optimised manner, which incorporates upstream residual amounts of pesticide through downstream carry. Using an optimisation technique applied in the West African Onchocerciasis Control Programme, to a 136 km stretch of the Orange River which includes 31 blackfly breeding sites, we demonstrate that 28.5% less larvicide could be used to potentially achieve the same control of blackfly. This translates into potential annual savings of between R540 000 and R1 800 000. A comparison of larvicide volumes estimated using traditional vs. optimised approaches at different discharges, illustrates that the savings on optimisation decline linearly with increasing flow volumes. Larvicide applications at the lowest discharge considered (40 m3·s-1) showed the greatest benefits from optimisations, with benefits remaining but decreasing to a theoretical 30% up to median flows of 100 m3·s-1. Given that almost 70% of flows in July are less than 100 m3·s-1, we suggest that an optimised approach is appropriate for the Orange River Blackfly Control Programme, particularly for flow volumes of less than 100 m3·s-1. We recommend that trials be undertaken over two reaches of the Orange River, one using the traditional approach, and another using the optimised approach, to test the efficacy of using optimised volumes of B.t.i.
- Full Text:
- Date Issued: 2008
- Authors: Rivers-Moore, Nick A , Bangay, Shaun D , Palmer, R W
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:7090 , http://hdl.handle.net/10962/d1012421
- Description: The Orange River, South Africa's largest river, is a critical water resource for the country. In spite of the clear economic benefits of regulating river flows through a series of impoundments, one of the significant undesirable ecological consequences of this regulation has been the regular outbreaks of the pest blackfly species Simulium chutteri and S. damnosum s.l. (Diptera: Simuliidae). The current control programme, carried out by the South African National Department of Agriculture, uses regular applications, by helicopter, of the target-specific bacterial larvicide Bacillus thuringiensis var. israelensis. While cost-benefit analyses show significant benefits to the control programme, benefits could potentially be further increased through applying smaller volumes of larvicide in an optimised manner, which incorporates upstream residual amounts of pesticide through downstream carry. Using an optimisation technique applied in the West African Onchocerciasis Control Programme, to a 136 km stretch of the Orange River which includes 31 blackfly breeding sites, we demonstrate that 28.5% less larvicide could be used to potentially achieve the same control of blackfly. This translates into potential annual savings of between R540 000 and R1 800 000. A comparison of larvicide volumes estimated using traditional vs. optimised approaches at different discharges, illustrates that the savings on optimisation decline linearly with increasing flow volumes. Larvicide applications at the lowest discharge considered (40 m3·s-1) showed the greatest benefits from optimisations, with benefits remaining but decreasing to a theoretical 30% up to median flows of 100 m3·s-1. Given that almost 70% of flows in July are less than 100 m3·s-1, we suggest that an optimised approach is appropriate for the Orange River Blackfly Control Programme, particularly for flow volumes of less than 100 m3·s-1. We recommend that trials be undertaken over two reaches of the Orange River, one using the traditional approach, and another using the optimised approach, to test the efficacy of using optimised volumes of B.t.i.
- Full Text:
- Date Issued: 2008
Oxbridge clerics and early ringing in South Africa
- Authors: Lewis, Colin A
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6186 , http://hdl.handle.net/10962/d1012384
- Description: During the early Twentieth Century, many gifted British clergy came to South Africa. They must have felt optimistic that many rings of bells would soon be installed in their adopted country. South Africa had survived the Boer Wars, the economy was reasonably healthy, new churches were being built and many others were being planned. The Union of South Africa was only a few years old and the political stability of this great part of the British Empire seemed assured. Sadly, their optimism was misplaced and in 2008 only eight rings exist in South Africa. Had it not been for the efforts of the Oxbridge trio: J.R. Vincent, G.H. Ridout and C.E.E. Bulwer, and other British immigrants, however, these rings would not exist. , Colin Lewis was Professor of Geography at Rhodes University, Grahamstown, South Africa from 1989 until his retirement at the end of 2007. In 1990, with the strong support of the incumbent Vice-Chancellor, Dr Derek Henderson, he instigated the Certificate in Change Ringing (Church Bell Ringing) in the Rhodes University Department of Music and Musicology - the first such course to be offered in Africa. Since that date he has lectured in the basic theory, and taught the practice of change ringing. He is the Ringing Master of the Cathedral of St Michael and St George, Grahamstown, South Africa.
- Full Text:
- Date Issued: 2008
- Authors: Lewis, Colin A
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6186 , http://hdl.handle.net/10962/d1012384
- Description: During the early Twentieth Century, many gifted British clergy came to South Africa. They must have felt optimistic that many rings of bells would soon be installed in their adopted country. South Africa had survived the Boer Wars, the economy was reasonably healthy, new churches were being built and many others were being planned. The Union of South Africa was only a few years old and the political stability of this great part of the British Empire seemed assured. Sadly, their optimism was misplaced and in 2008 only eight rings exist in South Africa. Had it not been for the efforts of the Oxbridge trio: J.R. Vincent, G.H. Ridout and C.E.E. Bulwer, and other British immigrants, however, these rings would not exist. , Colin Lewis was Professor of Geography at Rhodes University, Grahamstown, South Africa from 1989 until his retirement at the end of 2007. In 1990, with the strong support of the incumbent Vice-Chancellor, Dr Derek Henderson, he instigated the Certificate in Change Ringing (Church Bell Ringing) in the Rhodes University Department of Music and Musicology - the first such course to be offered in Africa. Since that date he has lectured in the basic theory, and taught the practice of change ringing. He is the Ringing Master of the Cathedral of St Michael and St George, Grahamstown, South Africa.
- Full Text:
- Date Issued: 2008
Photophysicochemical and Fluorescence quenching studies of benzyloxyphenoxy substituted zinc phthalocyanines
- Durmuş, Mahmut, Nyokong, Tebello
- Authors: Durmuş, Mahmut , Nyokong, Tebello
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6570 , http://hdl.handle.net/10962/d1004133
- Description: Photochemical and photophysical measurements were conducted on peripheral and non-peripheral tetrakis- and octakis(4-benzyloxyphenoxy)-substituted zinc phthalocyanines (1, 2 and 3). General trends are described for photodegradation, and fluorescence quantum yields, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds in dimethylsulphoxide (DMSO) and toluene. The fluorescence of the complexes is quenched by benzoquinone (BQ), and fluorescence quenching properties are investigated in DMSO and toluene. The effects of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (1, 2 and 3) are also reported. Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications.
- Full Text:
- Date Issued: 2008
- Authors: Durmuş, Mahmut , Nyokong, Tebello
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6570 , http://hdl.handle.net/10962/d1004133
- Description: Photochemical and photophysical measurements were conducted on peripheral and non-peripheral tetrakis- and octakis(4-benzyloxyphenoxy)-substituted zinc phthalocyanines (1, 2 and 3). General trends are described for photodegradation, and fluorescence quantum yields, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds in dimethylsulphoxide (DMSO) and toluene. The fluorescence of the complexes is quenched by benzoquinone (BQ), and fluorescence quenching properties are investigated in DMSO and toluene. The effects of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (1, 2 and 3) are also reported. Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications.
- Full Text:
- Date Issued: 2008
Relationship between energy intake and expenditure during harvesting tasks
- Authors: Christie, Candice J
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6758 , http://hdl.handle.net/10962/d1009461
- Description: The objective of this study was to compare the energy demands of manual harvesting tasks with the associated energy intake of the workers’. Fifty eight workers (29 Chainsaw Operators and 29 Stackers) were assessed in South Africa prior to, and during a ‘normal’ working shift. Habitual dietary analyses showed that the workers were eating less than 56% of the recommended daily allowance and were thus arriving at work with reduced energy stores. Heart rate responses were measured continuously during work and energy expenditure was predicted from the heart rate/oxygen uptake relationship obtained at a post-work progressive step up test completed by each worker. The data indicated that the tasks placed ‘moderate-to-heavy’ demands on the workers resulting in a significant imbalance between the energy demands of the tasks and the associated energy intake of the workers. Energy deficits were in excess of 8 000 kJ and workers lost, on average, 2.8% body mass during work while felling and cross-cutting, and 3.6% during stacking.
- Full Text:
- Date Issued: 2008
- Authors: Christie, Candice J
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6758 , http://hdl.handle.net/10962/d1009461
- Description: The objective of this study was to compare the energy demands of manual harvesting tasks with the associated energy intake of the workers’. Fifty eight workers (29 Chainsaw Operators and 29 Stackers) were assessed in South Africa prior to, and during a ‘normal’ working shift. Habitual dietary analyses showed that the workers were eating less than 56% of the recommended daily allowance and were thus arriving at work with reduced energy stores. Heart rate responses were measured continuously during work and energy expenditure was predicted from the heart rate/oxygen uptake relationship obtained at a post-work progressive step up test completed by each worker. The data indicated that the tasks placed ‘moderate-to-heavy’ demands on the workers resulting in a significant imbalance between the energy demands of the tasks and the associated energy intake of the workers. Energy deficits were in excess of 8 000 kJ and workers lost, on average, 2.8% body mass during work while felling and cross-cutting, and 3.6% during stacking.
- Full Text:
- Date Issued: 2008
Rhodes professor among best women scientists
- Authors: Ndabeni, Khanyi
- Date: 2008
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7186 , http://hdl.handle.net/10962/d1006278 , Nyokong, Tebello
- Description: A RHODES University scientist's ground breaking work in harnessing light for cancer therapy has won her a United Nations award worth almost R1- million. Named on Monday by the UN Educational, Scientific and Cultural Organisation (Unesco) as one of the world's top five "Exceptional Women Scientists", Professor Tebello Nyokong said winning the award was "just like getting a Nobel Prize". She was also recognised for her work regarding environmental cleanups. Nyokong, 57, grew up herding sheep in Lesotho and was unable to afford shoes. She now works in Rhodes University's chemistry department. She won the award for the Africa and Arab states category on World Science Day, which took place on Monday.
- Full Text:
- Date Issued: 2008
- Authors: Ndabeni, Khanyi
- Date: 2008
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7186 , http://hdl.handle.net/10962/d1006278 , Nyokong, Tebello
- Description: A RHODES University scientist's ground breaking work in harnessing light for cancer therapy has won her a United Nations award worth almost R1- million. Named on Monday by the UN Educational, Scientific and Cultural Organisation (Unesco) as one of the world's top five "Exceptional Women Scientists", Professor Tebello Nyokong said winning the award was "just like getting a Nobel Prize". She was also recognised for her work regarding environmental cleanups. Nyokong, 57, grew up herding sheep in Lesotho and was unable to afford shoes. She now works in Rhodes University's chemistry department. She won the award for the Africa and Arab states category on World Science Day, which took place on Monday.
- Full Text:
- Date Issued: 2008
SA scientist one of the top five female physical scientists
- Authors: Limson, Janice L
- Date: 2008
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7189 , http://hdl.handle.net/10962/d1006283 , http://www.scienceinafrica.co.za/2008/october/nyokong.htm
- Description: South African scientist Professor Tebello Nyokong scoops 2009 L’ORÉAL-UNESCO For Women in Science Award. Announced on November 10, South African scientist Professor Tebello Nyokong has become the first South African scientist to win the L’ORÉALUNESCO award for women in science for research in physical sciences.
- Full Text:
- Date Issued: 2008
- Authors: Limson, Janice L
- Date: 2008
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7189 , http://hdl.handle.net/10962/d1006283 , http://www.scienceinafrica.co.za/2008/october/nyokong.htm
- Description: South African scientist Professor Tebello Nyokong scoops 2009 L’ORÉAL-UNESCO For Women in Science Award. Announced on November 10, South African scientist Professor Tebello Nyokong has become the first South African scientist to win the L’ORÉALUNESCO award for women in science for research in physical sciences.
- Full Text:
- Date Issued: 2008
School principals' perceptions of team management : a multiple case-study of secondary schools
- Van der Mescht, Hennie, Tyala, Zakunzima
- Authors: Van der Mescht, Hennie , Tyala, Zakunzima
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6105 , http://hdl.handle.net/10962/d1009732
- Description: The notion of school management through teams (team management), though not a new phenomenon in South Africa, was formalized after the advent of democracy in 1994 and the subsequent reorganization of the education system. The concept was subsequently fleshed out in official documentation where the composition and roles of school management teams (SMTs) were elaborated upon. The notion of team management is rooted in theories that stress participation, notably site-based (school-based) management, teamwork, and distributed leadership. We report on a study in which the perceptions of secondary school principals, in Grahamstown, South Africa, of team management were explored. The study was interpretive in orientation, and utilized qualitative data gathering techniques in all (ten) of the state-aided secondary schools in Grahamstown in the Eastern Cape province. We found that, while team management was generally welcomed and even celebrated by principals, there were fundamental tensions surrounding principals' understanding of their leadership roles in a team context. We consider the implications of these findings for leadership development in the context of team management.
- Full Text:
- Date Issued: 2008
- Authors: Van der Mescht, Hennie , Tyala, Zakunzima
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6105 , http://hdl.handle.net/10962/d1009732
- Description: The notion of school management through teams (team management), though not a new phenomenon in South Africa, was formalized after the advent of democracy in 1994 and the subsequent reorganization of the education system. The concept was subsequently fleshed out in official documentation where the composition and roles of school management teams (SMTs) were elaborated upon. The notion of team management is rooted in theories that stress participation, notably site-based (school-based) management, teamwork, and distributed leadership. We report on a study in which the perceptions of secondary school principals, in Grahamstown, South Africa, of team management were explored. The study was interpretive in orientation, and utilized qualitative data gathering techniques in all (ten) of the state-aided secondary schools in Grahamstown in the Eastern Cape province. We found that, while team management was generally welcomed and even celebrated by principals, there were fundamental tensions surrounding principals' understanding of their leadership roles in a team context. We consider the implications of these findings for leadership development in the context of team management.
- Full Text:
- Date Issued: 2008
Shoppers Drug Mart or poachers Drug Mart?
- Attaran, Amir, Walker, Roderick B
- Authors: Attaran, Amir , Walker, Roderick B
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6346 , http://hdl.handle.net/10962/d1006018
- Description: [From the text]: Shoppers Drug Mart (Pharmaprix in Quebec) is a familiar Canadian institution. Its 1000 stores dot the landscape; no pharmacy chain is larger. In many Canadian communities, the corporation's well-staffed local franchises give patients quality care. However, in South Africa, the same corporation is potentially contributing to a public health disaster. In 2005, 2006 and twice in 2007, it has dispatched recruiters to that country, with the mission of plucking pharmacists from a continent that has far too few for its needs. Shoppers Drug Mart promises 6-figure salaries and help to establish a brilliant career in Canada. The carrot, and the helping hand holding it, are huge.
- Full Text:
- Date Issued: 2008
- Authors: Attaran, Amir , Walker, Roderick B
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6346 , http://hdl.handle.net/10962/d1006018
- Description: [From the text]: Shoppers Drug Mart (Pharmaprix in Quebec) is a familiar Canadian institution. Its 1000 stores dot the landscape; no pharmacy chain is larger. In many Canadian communities, the corporation's well-staffed local franchises give patients quality care. However, in South Africa, the same corporation is potentially contributing to a public health disaster. In 2005, 2006 and twice in 2007, it has dispatched recruiters to that country, with the mission of plucking pharmacists from a continent that has far too few for its needs. Shoppers Drug Mart promises 6-figure salaries and help to establish a brilliant career in Canada. The carrot, and the helping hand holding it, are huge.
- Full Text:
- Date Issued: 2008
Should active recruitment of health workers from sub-Saharan Africa be viewed as a crime?
- Mills, E J, Schabas, W A, Volmink, J, Walker, Roderick B, Ford, N, Katabira, E, Anema, A, Joffres, M, Cahn, P, Montaner, J
- Authors: Mills, E J , Schabas, W A , Volmink, J , Walker, Roderick B , Ford, N , Katabira, E , Anema, A , Joffres, M , Cahn, P , Montaner, J
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6392 , http://hdl.handle.net/10962/d1006314
- Description: (Conclusion) When the international community permits for-profit companies to actively entice overworked and often underpaid workers away from the most vulnerable populations, it is contributing to the deterioration of essential health-care delivery. Improvement of the health of the world’s poor is a challenge that the international community is failing to adequately address. Current international treaties and commitments are severely compromised if we are unwilling to adhere to their principles and prevent obvious harms to poor people. Clear, enforced regulation is needed to prevent recruitment companies from enticing health workers away from their local work, and developed countries should adequately compensate less-developed countries for the human resources they have lost and continue to lose.
- Full Text:
- Date Issued: 2008
- Authors: Mills, E J , Schabas, W A , Volmink, J , Walker, Roderick B , Ford, N , Katabira, E , Anema, A , Joffres, M , Cahn, P , Montaner, J
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6392 , http://hdl.handle.net/10962/d1006314
- Description: (Conclusion) When the international community permits for-profit companies to actively entice overworked and often underpaid workers away from the most vulnerable populations, it is contributing to the deterioration of essential health-care delivery. Improvement of the health of the world’s poor is a challenge that the international community is failing to adequately address. Current international treaties and commitments are severely compromised if we are unwilling to adhere to their principles and prevent obvious harms to poor people. Clear, enforced regulation is needed to prevent recruitment companies from enticing health workers away from their local work, and developed countries should adequately compensate less-developed countries for the human resources they have lost and continue to lose.
- Full Text:
- Date Issued: 2008
Social Services and Benefits
- Authors: Kruuse, Helen
- Date: 2008
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54211 , vital:26405 , https://store.lexisnexis.co.za/products/family-law-service-skuZASKUPG642
- Description: Family Law Service is a subscription based product including both the printed loose-leaf and LexisMobile publications. Updates for 12 months (print and mobile) are included in the price. Family Law Service covers aspects of law pertaining to the family, including domestic violence, the Law of Islam, same- sex life partnerships, the effects of the Children's Act, 2008 and anti-trafficking law in South Africa. Family Law Service is maintained in three volumes with commentary and legislation, and with two service issues published a year.
- Full Text: false
- Date Issued: 2008
- Authors: Kruuse, Helen
- Date: 2008
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54211 , vital:26405 , https://store.lexisnexis.co.za/products/family-law-service-skuZASKUPG642
- Description: Family Law Service is a subscription based product including both the printed loose-leaf and LexisMobile publications. Updates for 12 months (print and mobile) are included in the price. Family Law Service covers aspects of law pertaining to the family, including domestic violence, the Law of Islam, same- sex life partnerships, the effects of the Children's Act, 2008 and anti-trafficking law in South Africa. Family Law Service is maintained in three volumes with commentary and legislation, and with two service issues published a year.
- Full Text: false
- Date Issued: 2008
Sterols and sterolins in Hypoxis hemerocallidea (African potato)
- Nair, V D P, Kanfer, Isadore
- Authors: Nair, V D P , Kanfer, Isadore
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:6417 , http://hdl.handle.net/10962/d1006535
- Description: Commercially available health supplements and herbal remedies containing sterols and sterolins, either from African potato (Hypoxis hemerocallidea) alone, or whether enriched with sterols and sterolins, are claimed to be efficacious in the treatment of a variety of ailments. Sterols and sterolins in African potato are purported to be the relevant constituents that are required for the therapeutic claims of such products. A patent describing the extraction of sterolins from African potato plant material has claimed that approximately 9 mg sterolins can be isolated from 100 g of an enriched aqueous African potato extract. Our analysis of African potato plant material and its sterol and sterolin content, when similarly prepared, shows that the measureable content of sterols and sterolins in African potato is far less than the amounts of these compounds that have been claimed to be necessary for therapeutic benefit. We conclude that therapeutic claims relating to sterol and sterolin content in African potato are unsubstantiated, in view of the extremely low content of such compounds that we have isolated from our plant material, and in products containing African potato, or extracts thereof.
- Full Text:
- Date Issued: 2008
- Authors: Nair, V D P , Kanfer, Isadore
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:6417 , http://hdl.handle.net/10962/d1006535
- Description: Commercially available health supplements and herbal remedies containing sterols and sterolins, either from African potato (Hypoxis hemerocallidea) alone, or whether enriched with sterols and sterolins, are claimed to be efficacious in the treatment of a variety of ailments. Sterols and sterolins in African potato are purported to be the relevant constituents that are required for the therapeutic claims of such products. A patent describing the extraction of sterolins from African potato plant material has claimed that approximately 9 mg sterolins can be isolated from 100 g of an enriched aqueous African potato extract. Our analysis of African potato plant material and its sterol and sterolin content, when similarly prepared, shows that the measureable content of sterols and sterolins in African potato is far less than the amounts of these compounds that have been claimed to be necessary for therapeutic benefit. We conclude that therapeutic claims relating to sterol and sterolin content in African potato are unsubstantiated, in view of the extremely low content of such compounds that we have isolated from our plant material, and in products containing African potato, or extracts thereof.
- Full Text:
- Date Issued: 2008
Study of the formation of artifacts following Dichloromethane reaction with some nitrogenous drugs
- Mohammadi, Ali, Amini, Mohsen, Hamedani, Moteza P, Torkabadi, Hossein H, Walker, Roderick B
- Authors: Mohammadi, Ali , Amini, Mohsen , Hamedani, Moteza P , Torkabadi, Hossein H , Walker, Roderick B
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6409 , http://hdl.handle.net/10962/d1006495
- Description: In this work, the quaternization reaction of some nitrogenous drugs in dichloromethane under stress condition and room temperature at different times are studied. Under these conditions, drug-chloromethochloride adducts or artifacts were found to be formed for clozapine, ofloxacin and olanzapine. The structures of the resultant adducts were elucidated using 1H NMR spectroscopy. In addition, the amount of intact drug was determined using in-house validated HPLC methods with UV detection.
- Full Text:
- Date Issued: 2008
- Authors: Mohammadi, Ali , Amini, Mohsen , Hamedani, Moteza P , Torkabadi, Hossein H , Walker, Roderick B
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6409 , http://hdl.handle.net/10962/d1006495
- Description: In this work, the quaternization reaction of some nitrogenous drugs in dichloromethane under stress condition and room temperature at different times are studied. Under these conditions, drug-chloromethochloride adducts or artifacts were found to be formed for clozapine, ofloxacin and olanzapine. The structures of the resultant adducts were elucidated using 1H NMR spectroscopy. In addition, the amount of intact drug was determined using in-house validated HPLC methods with UV detection.
- Full Text:
- Date Issued: 2008
Temporal and spatial variability in stable isotope ratios of SPM link to local hydrography and longer term SPM averages suggest heavy dependence of mussels on nearshore production
- Hill, Jaclyn M, McQuaid, Christopher D, Kaehler, Sven
- Authors: Hill, Jaclyn M , McQuaid, Christopher D , Kaehler, Sven
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:6969 , http://hdl.handle.net/10962/d1012034
- Description: Temporal changes in hydrography affect suspended particulate matter (SPM) composition and distribution in coastal systems, potentially influencing the diets of suspension feeders. Temporal variation in SPM and in the diet of the mussel Perna perna, were investigated using stable isotope analysis. The δ13C and δ15 N ratios of SPM, mussels and macroalgae were determined monthly, with SPM samples collected along a 10 km onshore–offshore transect, over 14 months at Kenton-on-Sea, on the south coast of South Africa. Clear nearshore (0 km) to offshore (10 km) carbon depletion gradients were seen in SPM during all months and extended for 50 km offshore on one occasion. Carbon enrichment of coastal SPM in winter (June–August 2004 and May 2005) indicated temporal changes in the nearshore detrital pool, presumably reflecting changes in macroalgal detritus, linked to local changes in coastal hydrography and algal seasonality. Nitrogen patterns were less clear, with SPM enrichment seen between July and October 2004 from 0 to 10 km. Nearshore SPM demonstrated cyclical patterns in carbon over 24-h periods that correlated closely with tidal cycles and mussel carbon signatures, sampled monthly, demonstrated fluctuations that could not be correlated to seasonal or monthly changes in SPM. Macroalgae showed extreme variability in isotopic signatures, with no discernable patterns. IsoSource mixing models indicated over 50% reliance of mussel tissue on nearshore carbon, highlighting the importance of nearshore SPM in mussel diet. Overall, carbon variation in SPM at both large and small temporal scales can be related to hydrographic processes, but is masked in mussels by long-term isotope integration.
- Full Text:
- Date Issued: 2008
- Authors: Hill, Jaclyn M , McQuaid, Christopher D , Kaehler, Sven
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:6969 , http://hdl.handle.net/10962/d1012034
- Description: Temporal changes in hydrography affect suspended particulate matter (SPM) composition and distribution in coastal systems, potentially influencing the diets of suspension feeders. Temporal variation in SPM and in the diet of the mussel Perna perna, were investigated using stable isotope analysis. The δ13C and δ15 N ratios of SPM, mussels and macroalgae were determined monthly, with SPM samples collected along a 10 km onshore–offshore transect, over 14 months at Kenton-on-Sea, on the south coast of South Africa. Clear nearshore (0 km) to offshore (10 km) carbon depletion gradients were seen in SPM during all months and extended for 50 km offshore on one occasion. Carbon enrichment of coastal SPM in winter (June–August 2004 and May 2005) indicated temporal changes in the nearshore detrital pool, presumably reflecting changes in macroalgal detritus, linked to local changes in coastal hydrography and algal seasonality. Nitrogen patterns were less clear, with SPM enrichment seen between July and October 2004 from 0 to 10 km. Nearshore SPM demonstrated cyclical patterns in carbon over 24-h periods that correlated closely with tidal cycles and mussel carbon signatures, sampled monthly, demonstrated fluctuations that could not be correlated to seasonal or monthly changes in SPM. Macroalgae showed extreme variability in isotopic signatures, with no discernable patterns. IsoSource mixing models indicated over 50% reliance of mussel tissue on nearshore carbon, highlighting the importance of nearshore SPM in mussel diet. Overall, carbon variation in SPM at both large and small temporal scales can be related to hydrographic processes, but is masked in mussels by long-term isotope integration.
- Full Text:
- Date Issued: 2008