A stability-indicating HPLC assay with on-line clean-up for betamethasone 17-valerate in topical dosage forms
- Smith, Eric W, Haigh, John M, Kanfer, Isadore
- Authors: Smith, Eric W , Haigh, John M , Kanfer, Isadore
- Date: 1985
- Language: English
- Type: Article
- Identifier: vital:6421 , http://hdl.handle.net/10962/d1006556
- Description: A stability-indicating high-performance liquid chromatographic method with on-line clean-up has been developed for the analysis of betamethasone 17-valerate in topical dosage forms. A short pre-column containing 10 μm octadecylsilane mounted into the sample loop position of an injection valve was used as the primary clean-up step. The utilization of a diode-array UV detector allowed the quantitative analysis of betamethasone 17-valerate together with its degradation product, betamethasone 21-valerate, as well as the qualitative analysis of these compounds, relevant internal standards and the preservatives chlorocresol and methyl hydroxybenzoate contained in the cream and lotion formulations, respectively. Typically, cream and lotion dosage forms were dissolved in acetonitrile and ointments in tetrahydrofuran, internal standards added and aliquots injected onto the analytical system. Dosage form excipients were retained on the loop column and back-flushed to waste with the aid of a second solvent pump while components of interest were allowed to transfer to the analytical column for quantitative analysis. The method is accurate, precise and stability indicating and permits the rapid on-line analysis of betamethasone 17-valerate from complex topical formulation matrices without prior extractions.
- Full Text:
- Date Issued: 1985
- Authors: Smith, Eric W , Haigh, John M , Kanfer, Isadore
- Date: 1985
- Language: English
- Type: Article
- Identifier: vital:6421 , http://hdl.handle.net/10962/d1006556
- Description: A stability-indicating high-performance liquid chromatographic method with on-line clean-up has been developed for the analysis of betamethasone 17-valerate in topical dosage forms. A short pre-column containing 10 μm octadecylsilane mounted into the sample loop position of an injection valve was used as the primary clean-up step. The utilization of a diode-array UV detector allowed the quantitative analysis of betamethasone 17-valerate together with its degradation product, betamethasone 21-valerate, as well as the qualitative analysis of these compounds, relevant internal standards and the preservatives chlorocresol and methyl hydroxybenzoate contained in the cream and lotion formulations, respectively. Typically, cream and lotion dosage forms were dissolved in acetonitrile and ointments in tetrahydrofuran, internal standards added and aliquots injected onto the analytical system. Dosage form excipients were retained on the loop column and back-flushed to waste with the aid of a second solvent pump while components of interest were allowed to transfer to the analytical column for quantitative analysis. The method is accurate, precise and stability indicating and permits the rapid on-line analysis of betamethasone 17-valerate from complex topical formulation matrices without prior extractions.
- Full Text:
- Date Issued: 1985
A taxonomic and ecological review of Pseudocloeon glaucum (Agnew)(Ephemeroptera: Baetidae)
- Lugo-Ortiz, C R, De Moor, Ferdy C, Barber-James, Helen M
- Authors: Lugo-Ortiz, C R , De Moor, Ferdy C , Barber-James, Helen M
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:7007 , http://hdl.handle.net/10962/d1008385
- Description: Pseudocloeon masai (Lugo-Ortiz and McCafferty), P. nadineae (Lugo-Ortiz and McCafferty) and P. quintum (Agnew) are junior subjective synonyms of P. glaucum (Agnew). Larvae of P. glaucum manifest a wide range of variation in mouthpart morphology, particularly with respect to the development of the distomedial process of segment 2 of the labial palps, body size, general body colour and abdominal colour pattern. Such variation is observed in different cohorts and populations, and explains why several names have been applied to the same species. Larvae of P. glaucum also have considerable ecological tolerance, accounting for the abundance and widespread distribution of the species in the Afrotropical Region. New records from Kenya, Lesotho, Namibia and Zimbabwe are provided.
- Full Text:
- Date Issued: 2000
- Authors: Lugo-Ortiz, C R , De Moor, Ferdy C , Barber-James, Helen M
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:7007 , http://hdl.handle.net/10962/d1008385
- Description: Pseudocloeon masai (Lugo-Ortiz and McCafferty), P. nadineae (Lugo-Ortiz and McCafferty) and P. quintum (Agnew) are junior subjective synonyms of P. glaucum (Agnew). Larvae of P. glaucum manifest a wide range of variation in mouthpart morphology, particularly with respect to the development of the distomedial process of segment 2 of the labial palps, body size, general body colour and abdominal colour pattern. Such variation is observed in different cohorts and populations, and explains why several names have been applied to the same species. Larvae of P. glaucum also have considerable ecological tolerance, accounting for the abundance and widespread distribution of the species in the Afrotropical Region. New records from Kenya, Lesotho, Namibia and Zimbabwe are provided.
- Full Text:
- Date Issued: 2000
A technique for evaluating species richness maps generated from collections data
- Robertson, Mark P, Barker, Nigel P
- Authors: Robertson, Mark P , Barker, Nigel P
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6538 , http://hdl.handle.net/10962/d1005979
- Description: There is considerable pressure on conservation planners to use existing data from herbarium and museum collections for planning and monitoring, despite the weaknesses of such data. It is thus important to be able to assess the quality of this information. One application of these data is the production of species richness maps. However, sampling effort is generally not consistent throughout a region for maps generated from collections data, and it is thus desirable to identify geographic grid cells (such as quarter degree squares: QDS) for which there has been low sampling effort. We describe a technique that can be used to identify QDS that are likely to have low species richness that is due to insufficient sampling effort rather than to low actual species richness. The technique exploits relationships between climate and species richness to detect QDS that are poorly sampled. This approach offers advantages over the current practice of applying a single threshold across the entire map region to detectQDSthat are poorly sampled. Here we report on the application of our technique to plant species richness data in the PRECIS database. Results reveal that the majority of QDS in the Flora of Southern Africa region can be considered to be poorly sampled, even when using conservative thresholds for richness values. The advantages and weaknesses of the technique are discussed and issues requiring further investigation are highlighted.
- Full Text:
- Date Issued: 2006
- Authors: Robertson, Mark P , Barker, Nigel P
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6538 , http://hdl.handle.net/10962/d1005979
- Description: There is considerable pressure on conservation planners to use existing data from herbarium and museum collections for planning and monitoring, despite the weaknesses of such data. It is thus important to be able to assess the quality of this information. One application of these data is the production of species richness maps. However, sampling effort is generally not consistent throughout a region for maps generated from collections data, and it is thus desirable to identify geographic grid cells (such as quarter degree squares: QDS) for which there has been low sampling effort. We describe a technique that can be used to identify QDS that are likely to have low species richness that is due to insufficient sampling effort rather than to low actual species richness. The technique exploits relationships between climate and species richness to detect QDS that are poorly sampled. This approach offers advantages over the current practice of applying a single threshold across the entire map region to detectQDSthat are poorly sampled. Here we report on the application of our technique to plant species richness data in the PRECIS database. Results reveal that the majority of QDS in the Flora of Southern Africa region can be considered to be poorly sampled, even when using conservative thresholds for richness values. The advantages and weaknesses of the technique are discussed and issues requiring further investigation are highlighted.
- Full Text:
- Date Issued: 2006
A temporal dimension to the influence of pollen rewards on bee behaviour and fecundity in Aloe tenuior
- Duffy, Karl J, Johnson, Steven D, Peter, Craig I
- Authors: Duffy, Karl J , Johnson, Steven D , Peter, Craig I
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:6561 , http://hdl.handle.net/10962/d1011735 , http://dx.doi.org/10.1371/journal.pone.0094908
- Description: The net effect of pollen production on fecundity in plants can range from negative – when self-pollen interferes with fecundity due to incompatibility mechanisms, to positive – when pollen availability is associated with increased pollinator visitation and fecundity due to its utilization as a reward. We investigated the responses of bees to pollen and nectar rewards, and the effects of these rewards on pollen deposition and fecundity in the hermaphroditic succulent shrub Aloe tenuior. Self-pollinated plants failed to set fruit, but their ovules were regularly penetrated by self-pollen tubes, which uniformly failed to develop into seeds as expected from ovarian self-incompatibility (or strong early inbreeding depression). Bees consistently foraged for pollen during the morning and early afternoon, but switched to nectar in the late afternoon. As a consequence of this differential foraging, we were able to test the relative contribution to fecundity of pollen- versus nectar-collecting flower visitors. We exposed emasculated and intact flowers in either the morning or late afternoon to foraging bees and showed that emasculation reduced pollen deposition by insects in the morning, but had little effect in the afternoon. Despite the potential for self-pollination to result in ovule discounting due to late-acting self-sterility, fecundity was severely reduced in artificially emasculated plants. Although there were temporal fluctuations in reward preference, most bee visits were for pollen rewards. Therefore the benefit of providing pollen that is accessible to bee foragers outweighs any potential costs to fitness in terms of gender interference in this species.
- Full Text:
- Date Issued: 2014
- Authors: Duffy, Karl J , Johnson, Steven D , Peter, Craig I
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:6561 , http://hdl.handle.net/10962/d1011735 , http://dx.doi.org/10.1371/journal.pone.0094908
- Description: The net effect of pollen production on fecundity in plants can range from negative – when self-pollen interferes with fecundity due to incompatibility mechanisms, to positive – when pollen availability is associated with increased pollinator visitation and fecundity due to its utilization as a reward. We investigated the responses of bees to pollen and nectar rewards, and the effects of these rewards on pollen deposition and fecundity in the hermaphroditic succulent shrub Aloe tenuior. Self-pollinated plants failed to set fruit, but their ovules were regularly penetrated by self-pollen tubes, which uniformly failed to develop into seeds as expected from ovarian self-incompatibility (or strong early inbreeding depression). Bees consistently foraged for pollen during the morning and early afternoon, but switched to nectar in the late afternoon. As a consequence of this differential foraging, we were able to test the relative contribution to fecundity of pollen- versus nectar-collecting flower visitors. We exposed emasculated and intact flowers in either the morning or late afternoon to foraging bees and showed that emasculation reduced pollen deposition by insects in the morning, but had little effect in the afternoon. Despite the potential for self-pollination to result in ovule discounting due to late-acting self-sterility, fecundity was severely reduced in artificially emasculated plants. Although there were temporal fluctuations in reward preference, most bee visits were for pollen rewards. Therefore the benefit of providing pollen that is accessible to bee foragers outweighs any potential costs to fitness in terms of gender interference in this species.
- Full Text:
- Date Issued: 2014
APDUSA Views
- Date: 1990-07
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33147 , vital:32541 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1990-07
- Date: 1990-07
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33147 , vital:32541 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1990-07
APDUSA Views
- Date: 1988-03
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33167 , vital:32543 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1988-03
- Date: 1988-03
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33167 , vital:32543 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1988-03
APDUSA Views
- Date: 1986-11
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33323 , vital:32636 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1986-11
- Date: 1986-11
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33323 , vital:32636 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1986-11
APDUSA Views
- Date: 1989-12
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/32708 , vital:32312 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1989-12
- Date: 1989-12
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/32708 , vital:32312 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1989-12
APDUSA Views
- Date: 1992-04
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/32648 , vital:32304 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1992-04
- Date: 1992-04
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/32648 , vital:32304 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1992-04
APDUSA Views
- Date: 1988-06
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33137 , vital:32536 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1988-06
- Date: 1988-06
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33137 , vital:32536 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1988-06
APDUSA Views
- Date: 1988-09
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33600 , vital:32902 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1988-09
- Date: 1988-09
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33600 , vital:32902 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1988-09
APDUSA Views
- Date: 1994-09
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33630 , vital:32910 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1994-09
- Date: 1994-09
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33630 , vital:32910 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 1994-09
Applications of lead phthalocyanines embedded in electrospun fibers for the photoinactivation of Escherichia coli in water
- Osifeko, Olawale L, Nyokong, Tebello
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:7304 , http://hdl.handle.net/10962/d1020381
- Description: Lead (II) pyridyloxyphthalocyanine (PbTpyPc) and its quaternized form (PbTepyPc) were synthesized and the photophysical behavior examined. Low fluorescence quantum yields (ΦF) of 0.01 and 0.02 were observed for PbTepyPc and PbTpyPc, respectively. The singlet oxygen quantum yields (ΦΔ) were 0.60 and 0.68, for PbTepyPc and PbTpyPc, respectively using DPBF as a quencher in DMF. Singlet oxygen production of the embedded sensitizers in electrospun fiber were quantified using ADMA and were found to be ΦΔ = 0.41 and ΦΔ = 0.21 for PbTepyPc and PbTpyPc, respectively. Photodynamic inactivation of Escherichia coli (E. coli) with the quaternized photosensitizer at 5 μM, totally inactivated the E. coli (with log CFU = 10 decrease). Only 0.4 log CFU decrease was obtained with PbTpyPc. The embedded non-quaternized photosensitizer (PbTpyPc) was less active on the gram negative bacteria but the quaternized photosensitizer (PbTepyPc) was effective towards inactivation of E. coli. , Original publication is available at http://dx.doi.org/10.1016/j.dyepig.2014.05.010
- Full Text: false
- Date Issued: 2014
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:7304 , http://hdl.handle.net/10962/d1020381
- Description: Lead (II) pyridyloxyphthalocyanine (PbTpyPc) and its quaternized form (PbTepyPc) were synthesized and the photophysical behavior examined. Low fluorescence quantum yields (ΦF) of 0.01 and 0.02 were observed for PbTepyPc and PbTpyPc, respectively. The singlet oxygen quantum yields (ΦΔ) were 0.60 and 0.68, for PbTepyPc and PbTpyPc, respectively using DPBF as a quencher in DMF. Singlet oxygen production of the embedded sensitizers in electrospun fiber were quantified using ADMA and were found to be ΦΔ = 0.41 and ΦΔ = 0.21 for PbTepyPc and PbTpyPc, respectively. Photodynamic inactivation of Escherichia coli (E. coli) with the quaternized photosensitizer at 5 μM, totally inactivated the E. coli (with log CFU = 10 decrease). Only 0.4 log CFU decrease was obtained with PbTpyPc. The embedded non-quaternized photosensitizer (PbTpyPc) was less active on the gram negative bacteria but the quaternized photosensitizer (PbTepyPc) was effective towards inactivation of E. coli. , Original publication is available at http://dx.doi.org/10.1016/j.dyepig.2014.05.010
- Full Text: false
- Date Issued: 2014
Assessing the potential for biological invasion - the case of Ammophila arenaria in South Africa
- Hertling, Ursula M, Lubke, Roy
- Authors: Hertling, Ursula M , Lubke, Roy
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:6518 , http://hdl.handle.net/10962/d1005947
- Description: Many plants, especially woody species, introduced into South Africa for ornamental or commercial purposes, have become invasive in a number of habitats. Because of the risk of an invasion of coastal dunes by yet another species, the European dune grass Ammophila arenaria, used as a dune stabilizer, is assessed using lists of attributes of invasive species and invasible ecosystems. It is impossible to predict plant invasions, but both invasive species as well as invaded ecosystems are often characterized by certain attributes which facilitate invasions. Many of the species attributes connected with invasion appear to apply to A. arenaria. Above all, the grass is characterized by ecological tolerance and vigorous rhizomatous reproduction. An important site attribute connected with invasion is an evolutionary history with isolation patterns, which applies to the South African Cape coast. We conclude also on the basis of the overseas experience, that the potential for A. arenaria to become invasive needs urgent investigation in the South African context.
- Full Text: false
- Date Issued: 2000
- Authors: Hertling, Ursula M , Lubke, Roy
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:6518 , http://hdl.handle.net/10962/d1005947
- Description: Many plants, especially woody species, introduced into South Africa for ornamental or commercial purposes, have become invasive in a number of habitats. Because of the risk of an invasion of coastal dunes by yet another species, the European dune grass Ammophila arenaria, used as a dune stabilizer, is assessed using lists of attributes of invasive species and invasible ecosystems. It is impossible to predict plant invasions, but both invasive species as well as invaded ecosystems are often characterized by certain attributes which facilitate invasions. Many of the species attributes connected with invasion appear to apply to A. arenaria. Above all, the grass is characterized by ecological tolerance and vigorous rhizomatous reproduction. An important site attribute connected with invasion is an evolutionary history with isolation patterns, which applies to the South African Cape coast. We conclude also on the basis of the overseas experience, that the potential for A. arenaria to become invasive needs urgent investigation in the South African context.
- Full Text: false
- Date Issued: 2000
Baited traps may be an alternative to conventional pesticides in the integrated crop management of chicory (Compositae) in South Africa
- Midgley, John M, Hill, Martin P, Villet, Martin H
- Authors: Midgley, John M , Hill, Martin P , Villet, Martin H
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6858 , http://hdl.handle.net/10962/d1011141 , http://dx.doi.org/10.1603/0022-0493(2008)101[99:BTMBAA]2.0.CO;2 , https://orcid.org/0000-0003-0579-5298
- Description: Chicory, Chicorium intybus L. (Compositae), is a major field crop in the Eastern Cape Province of South Africa. Several pests feed on the leaves of the plant, resulting in reduced yield. The most important of these are the noctuid moths Helicoverpa armigera (Hübner), Chrysodeixis acuta (Walker), and Trichoplusia orichalcea (F.). The use of attract-and-kill traps offers an alternative to broad-based insecticides in the control of these species. Three fields were treated with normal insecticides and three fields with yellow-baited traps. Eight additional traps were placed in each field, with half of the traps containing the insecticide 2,2-dichlorovinyl dimethyl phosphate (dichlorvos) and half without dichlorvos; and half yellow and half green. Total moth numbers and nonphytophage diversity were measured from these eight traps. Although no differences in H. armigera or T. orichalcea catches were observed between insecticide- and trap-treated fields, numbers of C. acuta and the total number of moths were significantly higher in insecticide-treated fields. Yellow traps containing dichlorvos contained more moths than yellow traps without dichlorvos, or green traps with dichlorvos, or green traps without dichlorvos; but they also contained more nonphytophagous insects. Yellow traps also enhanced the catches of thrips on card traps associated with them. These results offer an opportunity for the South African chicory industry to reduce pesticide applications and thus mitigate environmental impacts.
- Full Text:
- Date Issued: 2008
- Authors: Midgley, John M , Hill, Martin P , Villet, Martin H
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6858 , http://hdl.handle.net/10962/d1011141 , http://dx.doi.org/10.1603/0022-0493(2008)101[99:BTMBAA]2.0.CO;2 , https://orcid.org/0000-0003-0579-5298
- Description: Chicory, Chicorium intybus L. (Compositae), is a major field crop in the Eastern Cape Province of South Africa. Several pests feed on the leaves of the plant, resulting in reduced yield. The most important of these are the noctuid moths Helicoverpa armigera (Hübner), Chrysodeixis acuta (Walker), and Trichoplusia orichalcea (F.). The use of attract-and-kill traps offers an alternative to broad-based insecticides in the control of these species. Three fields were treated with normal insecticides and three fields with yellow-baited traps. Eight additional traps were placed in each field, with half of the traps containing the insecticide 2,2-dichlorovinyl dimethyl phosphate (dichlorvos) and half without dichlorvos; and half yellow and half green. Total moth numbers and nonphytophage diversity were measured from these eight traps. Although no differences in H. armigera or T. orichalcea catches were observed between insecticide- and trap-treated fields, numbers of C. acuta and the total number of moths were significantly higher in insecticide-treated fields. Yellow traps containing dichlorvos contained more moths than yellow traps without dichlorvos, or green traps with dichlorvos, or green traps without dichlorvos; but they also contained more nonphytophagous insects. Yellow traps also enhanced the catches of thrips on card traps associated with them. These results offer an opportunity for the South African chicory industry to reduce pesticide applications and thus mitigate environmental impacts.
- Full Text:
- Date Issued: 2008
Bi-Alexandroff spaces
- Authors: Matutu, Phethiwe P
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6782 , http://hdl.handle.net/10962/d1006925
- Description: Bi-Alexandroff spaces are defined as extensions of Alexandroff spaces [1]. Urysohn’s lemma for bi-Alexandroff spaces is used to show that upper and lower cozero sets of bitopological spaces are bi-Alexandroff spaces. An adjunction between bi-Alexandroff spaces and pairwise completely regular bitopological spaces is established.
- Full Text:
- Date Issued: 2007
- Authors: Matutu, Phethiwe P
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6782 , http://hdl.handle.net/10962/d1006925
- Description: Bi-Alexandroff spaces are defined as extensions of Alexandroff spaces [1]. Urysohn’s lemma for bi-Alexandroff spaces is used to show that upper and lower cozero sets of bitopological spaces are bi-Alexandroff spaces. An adjunction between bi-Alexandroff spaces and pairwise completely regular bitopological spaces is established.
- Full Text:
- Date Issued: 2007
Biological responses to a resumption in river flow in a freshwater-deprived, permanently open Southern African estuary
- Vorwerk, Paul D, Froneman, P William, Paterson, Angus W, Strydom, Nadine A, Whitfield, A K
- Authors: Vorwerk, Paul D , Froneman, P William , Paterson, Angus W , Strydom, Nadine A , Whitfield, A K
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:6886 , http://hdl.handle.net/10962/d1011645
- Description: The Kariega Estuary is a freshwater-deprived system due to numerous impoundments in the catchment. This system has had little or no horizontal salinity gradient over the last 15 years, with hypersaline conditions sometimes predominating in the upper reaches. Following high rainfall events in the catchment during the spring of 2006, including a flood event (approximate 1:10 year) in August 2006, a series of riverine pulses entered the estuary and a horizontal salinity gradient was established. This study examined the influence of this freshwater pulse on four components of the biota within the estuary, namely the zooplankton, and larval, littoral and demersal fishes. The study demonstrated that in three of these components elevated densities were recorded following the riverine input, with only the littoral fishes retaining an almost constant density. In addition, changes in the relative contributions of the estuarine utilisation classes for all three fish groups examined indicated that freshwater input into these systems positively influences the abundances. This has significant implications for water managers as it demonstrates the importance of an Ecological Reserve (defined as ‘the water required to protect the aquatic ecosystems of the water resource’) for this system.
- Full Text:
- Date Issued: 2008
- Authors: Vorwerk, Paul D , Froneman, P William , Paterson, Angus W , Strydom, Nadine A , Whitfield, A K
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:6886 , http://hdl.handle.net/10962/d1011645
- Description: The Kariega Estuary is a freshwater-deprived system due to numerous impoundments in the catchment. This system has had little or no horizontal salinity gradient over the last 15 years, with hypersaline conditions sometimes predominating in the upper reaches. Following high rainfall events in the catchment during the spring of 2006, including a flood event (approximate 1:10 year) in August 2006, a series of riverine pulses entered the estuary and a horizontal salinity gradient was established. This study examined the influence of this freshwater pulse on four components of the biota within the estuary, namely the zooplankton, and larval, littoral and demersal fishes. The study demonstrated that in three of these components elevated densities were recorded following the riverine input, with only the littoral fishes retaining an almost constant density. In addition, changes in the relative contributions of the estuarine utilisation classes for all three fish groups examined indicated that freshwater input into these systems positively influences the abundances. This has significant implications for water managers as it demonstrates the importance of an Ecological Reserve (defined as ‘the water required to protect the aquatic ecosystems of the water resource’) for this system.
- Full Text:
- Date Issued: 2008
Critical perspectives on research on post-traumatic stress disorder and implications for the South African context
- Authors: Edwards, David J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6228 , http://hdl.handle.net/10962/d1007778
- Description: This article introduces a special issue of the Journal of Psychology in Africa on post-traumatic stress disorder (PTSD) in Africa and particularly in South Africa and examines the critical debate that has surrounded PTSD research. It begins with an examination of the meaning of the term trauma, and of its specialised use within the clinical context and with respect to the concept of PTSD. The diagnostic approach to the detection of PTSD is presented, criteria in the DSM-IV-TR and the ICD-10 are summarised and differences between the two manuals are discussed. Arguments presented by critics of the concept of PTSD are presented and discussed. These concern the historical evolution of the concept, concerns about the universality of PTSD cross-culturally, and problems arising from understanding human suffering from a narrow medical perspective. It is concluded that while there are dangers in thinking of the sequelae of trauma as a medical/psychiatric problem, and while the alarming rate of traumatic events needs to be addressed at the political, economic and societal level, there is an important place for the provision of assessment and treatment of PTSD within a psychiatric/psychological clinical setting.
- Full Text:
- Date Issued: 2005
- Authors: Edwards, David J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6228 , http://hdl.handle.net/10962/d1007778
- Description: This article introduces a special issue of the Journal of Psychology in Africa on post-traumatic stress disorder (PTSD) in Africa and particularly in South Africa and examines the critical debate that has surrounded PTSD research. It begins with an examination of the meaning of the term trauma, and of its specialised use within the clinical context and with respect to the concept of PTSD. The diagnostic approach to the detection of PTSD is presented, criteria in the DSM-IV-TR and the ICD-10 are summarised and differences between the two manuals are discussed. Arguments presented by critics of the concept of PTSD are presented and discussed. These concern the historical evolution of the concept, concerns about the universality of PTSD cross-culturally, and problems arising from understanding human suffering from a narrow medical perspective. It is concluded that while there are dangers in thinking of the sequelae of trauma as a medical/psychiatric problem, and while the alarming rate of traumatic events needs to be addressed at the political, economic and societal level, there is an important place for the provision of assessment and treatment of PTSD within a psychiatric/psychological clinical setting.
- Full Text:
- Date Issued: 2005
Designer ligands : the search for metal ion selectivity
- Authors: Kaye, P T
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6576 , http://hdl.handle.net/10962/d1004139
- Description: The paper reviews research conducted at Rhodes University towards the development of metal-selective ligands. The research has focused on the rational design, synthesis and evaluation of novel ligands for use in the formation of copper complexes as biomimetic models of the metalloenzyme, tyrosinase, and for the selective extraction of silver, nickel and platinum group metal ions in the presence of contaminating metal ions. Attention has also been given to the development of efficient, metal-selective molecular imprinted polymers.
- Full Text:
- Date Issued: 2011
- Authors: Kaye, P T
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6576 , http://hdl.handle.net/10962/d1004139
- Description: The paper reviews research conducted at Rhodes University towards the development of metal-selective ligands. The research has focused on the rational design, synthesis and evaluation of novel ligands for use in the formation of copper complexes as biomimetic models of the metalloenzyme, tyrosinase, and for the selective extraction of silver, nickel and platinum group metal ions in the presence of contaminating metal ions. Attention has also been given to the development of efficient, metal-selective molecular imprinted polymers.
- Full Text:
- Date Issued: 2011
Does the endangered Knysna seahorse, Hippocampus capensis, have a preference for aquatic vegetation type, cover or height?
- Teske, Peter R, Lockyear, Jaqueline F, Hecht, Thomas, Kaiser, Horst
- Authors: Teske, Peter R , Lockyear, Jaqueline F , Hecht, Thomas , Kaiser, Horst
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6775 , http://hdl.handle.net/10962/d1008082
- Description: The Knysna seahorse, Hippocampus capensis, is an endangered teleost confined to three South African estuaries. Its abundance within these systems is low and distributions are patchy. Consequently, monitoring population sizes is labour-intensive. The aim of this study was to establish if Knynsa seahorses are associated with specific regions within the estuaries, on which conservation efforts could concentrate. The relationship of Knysna seahorses with aquatic vegetation was analysed in the Knysna Estuary (the largest of the three estuarine systems inhabited by H. capensis) to determine whether this species shows a preference for a particular plant species, vegetation density or vegetation height. Seahorses were associated with five dominant aquatic plants: Zostera capensis, Caulerpa filiformis, Codium extricatum, Halophila ovalis and Ruppia cirrhosa. Together, these comprised 96% of the submerged objects with which seahorses were associated. The relative abundance of plant species changed along the estuary, but seahorses were present throughout the system, except at the estuary mouth, which was characterized by low plant densities and strong currents. No significant difference was found between the proportion of plant species present in a particular region of the estuary and the proportion of plants that seahorses used as holdfasts. However, when Z. capensis and C. filiformis were present at the same sites, adult seahorses preferred C. filiformis as holdfast. Adult seahorse density (individuals/m²) was significantly correlated with percentage vegetation cover and with holdfast length, but juvenile seahorse density was not. Nonetheless, significantly more adult and juvenile seahorses were found at sites characterized by high vegetation cover (>75%) than at sites with lower cover. Our results indicate that although there is some evidence that Knynsa seahorses prefer certain plant species over others, they are likely to be encountered anywhere in the estuary where aquatic plants are present. Conservation efforts in the Knysna Estuary should thus concentrate on such vegetated areas, which comprise approximately 11% of the total submerged surface area.
- Full Text:
- Date Issued: 2007
- Authors: Teske, Peter R , Lockyear, Jaqueline F , Hecht, Thomas , Kaiser, Horst
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6775 , http://hdl.handle.net/10962/d1008082
- Description: The Knysna seahorse, Hippocampus capensis, is an endangered teleost confined to three South African estuaries. Its abundance within these systems is low and distributions are patchy. Consequently, monitoring population sizes is labour-intensive. The aim of this study was to establish if Knynsa seahorses are associated with specific regions within the estuaries, on which conservation efforts could concentrate. The relationship of Knysna seahorses with aquatic vegetation was analysed in the Knysna Estuary (the largest of the three estuarine systems inhabited by H. capensis) to determine whether this species shows a preference for a particular plant species, vegetation density or vegetation height. Seahorses were associated with five dominant aquatic plants: Zostera capensis, Caulerpa filiformis, Codium extricatum, Halophila ovalis and Ruppia cirrhosa. Together, these comprised 96% of the submerged objects with which seahorses were associated. The relative abundance of plant species changed along the estuary, but seahorses were present throughout the system, except at the estuary mouth, which was characterized by low plant densities and strong currents. No significant difference was found between the proportion of plant species present in a particular region of the estuary and the proportion of plants that seahorses used as holdfasts. However, when Z. capensis and C. filiformis were present at the same sites, adult seahorses preferred C. filiformis as holdfast. Adult seahorse density (individuals/m²) was significantly correlated with percentage vegetation cover and with holdfast length, but juvenile seahorse density was not. Nonetheless, significantly more adult and juvenile seahorses were found at sites characterized by high vegetation cover (>75%) than at sites with lower cover. Our results indicate that although there is some evidence that Knynsa seahorses prefer certain plant species over others, they are likely to be encountered anywhere in the estuary where aquatic plants are present. Conservation efforts in the Knysna Estuary should thus concentrate on such vegetated areas, which comprise approximately 11% of the total submerged surface area.
- Full Text:
- Date Issued: 2007