A description of gametogenesis in the panga Pterogymnus laniarius (Pisces: Sparidae) with comments on changes in maturity patterns over the past two decades
- Authors: Booth, Anthony J , Hecht, Thomas
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123542 , vital:35452 , https://doi.org/10.1080/02541858.1997.11448428
- Description: A description of gametogenesis in the panga Pferogymnus laniarius, a common endemic seabream species inhabiting the Agulhas Bank, South Africa, is presented. After sexual maturity, oogenesis and spermatogenesis continued throughout the year and were found to be similar to these processes in other seabream species and teleosts in general. Analysis of maturity data over the past two decades revealed a significant change in both age and size-at-maturity, a response to fishing pressure.
- Full Text:
- Date Issued: 2015
A model for the analysis of small group interaction–and beyond?:
- Authors: Hunt, Sally
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/139171 , vital:37711 , DOI: 10.1080/10118063.1997.9724122
- Description: This article describes a branching model developed for the analysis of interaction in small teaching groups in a tertiary setting. Based within Conversation Analysis, the model constitutes a set of justifications for the validity of utterances in terms of their place on the conversational floor. Examples of the classifications included in the model are provided from a broader study of interaction in tutorials at an Eastern Cape university. It is suggested that while the model was developed for a specific context, it could be adapted for use in a variety of contexts.
- Full Text:
- Date Issued: 2012
The effects of economic incentives in controlling pollution in the South African leather industry: die uitwerking van ekonomiese insentiewe op die beheer van besoedeling in die Suid-Afrikaanse leerbedryf
- Authors: Mowat, Shaun P , Antrobus, Geoffrey G , Fraser, Gavin C G
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143057 , vital:38197 , DOI: 10.1080/03031853.1997.9523487
- Description: Pollution of the environment is becoming an increasingly serious problem. A large contributor to this is industry which generates effluent as a by-product of its production process. Two methods of controlling the pollution generated by industry are the so-called “command and control” techniques and economic incentives. In theory, economic incentives promise a more economically efficient and equitable means of pollution control. This paper sets out to ascertain whether this would hold in practice by applying environmental economic theory to the practical problem of controlling the effluent generated by one particular industry, viz the South African leather industry.
- Full Text:
- Date Issued: 2010
A description of gametogenesis in the panga Pterogymnus laniarius (Pisces: Sparidae) with comments on changes in maturity patterns over the past two decades
- Authors: Booth, Anthony J , Hecht, Thomas
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446930 , vital:74571 , https://www.ajol.info/index.php/az/article/view/154565
- Description: A description of gametogenesis in the panga Pferogymnus laniarius, a common endemic seabream species inhabiting the Agulhas Bank, South Africa, is presented. After sexual maturity, oogenesis and spermatogenesis continued throughout the year and were found to be similar to these processes in other seabream species and teleosts in general. Analysis of maturity data over the past two decades revealed a significant change in both age and size-at-maturity, a response to fishing pressure.
- Full Text:
- Date Issued: 1997
Apparent range expansion of the redbilled quelea Quelea quelea in the Eastern Cape Province of South Africa
- Authors: Whittington-Jones, C A
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448426 , vital:74729 , https://doi.org/10.1080/00306525.1997.9639720
- Description: Distribution records obtained from the South African Bird Atlas Project (SABAP) and from published literature show that the known distribution of Redbilled Quelea in the Eastern Cape has changed dramatically over the last century. Increased search effort following the initiation of SABAP may explain the range expansion, but changes in agricultural practice have probably been a contributing factor.
- Full Text:
- Date Issued: 1997
Book Review: 1001 activities in environmental education
- Authors: Janse van Rensberg, Eureta
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/438683 , vital:73490 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137449"
- Description: Book Title. 1001 activities in environmental educa-tion (1997). Book Author. Nico Allers. Publisher. Kamel eon Publishers, Vereeniging
- Full Text:
- Date Issued: 1997
Catalytic behavior of osmium (II), rhodium (III) and ruthenium (II) Phthalocyanines towards the electrooxidation of cysteine on glassy carbon electrodes
- Authors: Sekota, Mantoa , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293290 , vital:57072 , xlink:href=" https://doi.org/10.1002/elan.1140091608"
- Description: Glassy carbon electrodes (GCE's) modified with phthalocyanine complexes of Rh, Ru and Os are employed for the catalytic oxidation of cysteine. When cyanide and dimethylsulfoxide (DMSO) are used as axial ligands giving (DMSO)(Cl)RhIIIPc, [(CN)2RhIIIPc]−, (DMSO)2OsPcII, and [(DMSO)2Ru(II)Pc]·2DMSO complexes, the peak currents for the oxidation of cysteine increase after each scan, indicating an increase in the catalytic activity of the electrode with repetitive scanning. This improvement in the catalytic activity of the GCE after the first scan is attributed to the formation of dimeric π cation radical species at the electrode surface.
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- Date Issued: 1997
Ecology and genetics of hybrid zones in the southern African Pycnonotus bulbul species complex
- Authors: Lloyd, Penn , Craig, Adrian J F K , Hulley, Patrick E , Essop, M Faadiel , Bloomer, Paulette , Crowe, Timothy M
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447801 , vital:74675 , https://doi.org/10.1080/00306525.1997.9639720
- Description: The closely related Blackeyed Bulbul Pycnonotus barbatus, Cape Bulbul P. capensis and Redeyed Bulbul P. nigricans have parapatric to locally sympatric distributions within southern Africa. Extensive hybridization along narrow transition zones between each of the three species pairs is described in a region of the Eastern Cape province, South Africa. The transition zones coincide with ecotones between different vegetation types, which in turn follow escarpments or mountain ranges. The lack of population density depressions within the hybrid zones, together with the variability of the hybrids, suggests the hybrids are viable. Sharp step clines in various phenotypic characters are described across the P. barbatus/P. nigricans hybrid zone. A mtDNA analysis found evidence of possible introgression between P. barbatus and P. capensis. All eight P. barbatus x P. nigricans hybrids analysed possessed P. barbatus mtDNA, suggesting the existence of either positive assortative mating or strong directional selection, but our data are unable to distinguish which.
- Full Text:
- Date Issued: 1997
First-row transition metal phthalocyanines as catalysts for water electrolysis
- Authors: Chebotareva, Natalia , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293391 , vital:57081 , xlink:href="https://doi.org/10.1016/S0013-4686(97)00033-9"
- Description: Modification of carbon electrodes with first row transition metal phthalocyanines results in the lowering of the potentials needed for water electrolysis in basic media, by 600 to 700 mV when compared to unmodified carbon electrodes. Nickel(II), cobalt(II) and iron(II) phthalocyanines show higher catalytic activity than zinc(II), manganese(II), copper(II) and metal free phthalocyanines.
- Full Text:
- Date Issued: 1997
Glandular trichomes on the exotic Solanum sisymbriifolium Lamarck (Solanaceae): effective deterrents against an indigenous South African herbivore
- Authors: Hill, Martin P , Hulley, Patrick E , Allsopp, J , van Harmelen, G
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451413 , vital:75047 , https://hdl.handle.net/10520/AJA10213589_152
- Description: An examination of the leaves of several native and exotic Solanum species revealed that they all possessed glandular and non-glandular trichomes. The density of glandular trichomes was, however, very much lower on the leaves of the indigenous species than on the leaves of a weed species, Solanum sisymbriifolium Lamarck, and two other South American Solanum species. This difference could have contributed to the depauperate faunas supported by the exotic species. The morphology and behaviour of an indigenous Solanum-feeding tortoise beetle, Conchyloctenia tigrina Oliver (Coleoptera: Chrysomelidae), and a South American tortoise beetle, Gratiana spadicea (IQug) (Coleoptera: Chrysomelidae), were compared. The study revealed that while the exudate produced by the glandular trichomes afforded S. sisymbriifolium a level of resistance to C. tigrina, it is probably only one of the factors limiting the recruitment of indigenous herbivores onto S. sisymbriifolium.
- Full Text:
- Date Issued: 1997
Management education and training
- Authors: Amos, Trevor L , Quinn, Lynn
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270902 , vital:54490 , xlink:href="https://hdl.handle.net/10520/AJA10113487_559"
- Description: The paper outlines the role of language in leaming and cognitive development and argues that management education and training needs to be integrated with language development to enable students to cope with the demands made of them at university as well as with those of careers in the business world. An integrated language developmEint project developed by the Depanment of Management and academic language practitioners at Rhodes Uhlvetsity is descriptionbed and suggestions are outlined as to how university Management departments can integrate language development in their mainstream teaching.
- Full Text:
- Date Issued: 1997
Metallophthalocyanine catalysed electroreduction of nitrate and nitrite ions in alkaline media
- Authors: Chebotareva, Natalia , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293301 , vital:57073 , xlink:href="https://doi.org/10.1023/A:1018466021838"
- Description: Copper, cadmium, lead and bismuth (> 5 μg ml−1) are determined by adsorptive cathodic stripping voltammetry (AdCSV) on a mercury film glassy carbon electrode, using catechol, 4-methylcatechol, 4-t-butylcatechol and resorcinol as complexing ligands. Complexes of lead, copper and bismuth with resorcinol showed the largest increase in current with increase in metal concentration, whereas complexes of these metals with 4-t-butylcatechol showed the lowest current response. Cadmium showed a different behaviour from the other three metals in that the highest current response was observed with 4-methylcatechol. The four metals could be determined simultaneously in the presence of resorcinol, although considerable interference was observed between bismuth and copper.
- Full Text: false
- Date Issued: 1997
Multivariate analysis of honeybee populations, Apis mellifera Linnaeus (Hymenoptera: Apidae), from western central Africa morphometries and pheromones
- Authors: Radloff, Sarah E , Hepburn, H Randall
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451963 , vital:75091 , https://hdl.handle.net/10520/AJA10213589_298
- Description: Morphometric characters and sting pheromones of worker honeybees, Apis mellifera Linnaeus, were analysed by multivariate methods to characterize their populations along a transect through three ecological-climatological zones in Cameroon. There are three distinct homogeneous populations and two zones of hybridization. These bees are designated as A. m. adansollii Latreille whose area of distribution is intruded by an A. m. montieola-like montane group of bees and a third group, A. m. jemertitica Ruttner. The delineation of the hybrid zones is supported by intercolonial variance spectra and these significant asymmetries are coincident with transitions between the ecological-climatological zones.
- Full Text:
- Date Issued: 1997
Multivariate analysis of honeybees, Apis mellifera Linnaeus (Hymenoptera: Apidae), of the Horn of Africa
- Authors: Radloff, Sarah E , Hepburn, H Randall
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451987 , vital:75093 , https://hdl.handle.net/10520/AJA10213589_154
- Description: Morphometric characters and sting pheromones of worker honeybees, Apis mellifera Linnaeus, were analysed by multivariate methods to delineate the honeybee populations of the Horn of Africa. Four discrete and statistically homogeneous populations were identified: A. m. jemenitica Ruttner, A. m. bandasii Mogga, A. m. sudanensis Rashad in Ethiopia and an unclassified group in southwestern Somalia. Areas of high intercolonial variance are interpreted as zones of hybridization between the populations.
- Full Text:
- Date Issued: 1997
New placoderm fishes from the Late Devonian of South Africa
- Authors: Long, John A , Anderson, M Eric , Gess, Robert W , Hiller, Norton
- Date: 1997
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/72763 , vital:30108 , https://doi.org/10.1080/02724634.1997.10010973
- Description: New placoderm fishes are described from a black shale lens in the Famennian Witpoort Formation, near Grahamstown, South Africa. Arthrodires include a new species of Groenlandaspis, G. riniensis sp. nov., a new genus of groenlandaspidid, Africanaspis doryssa gen. et sp. nov., and a new species of the antiarch Bothriolepis, B. africana sp. nov. This is the first record of the ubiquitous genera Bothriolepis and Groenlandaspis from the African continent. The South African placoderm fauna has demonstrable links with the eastern Gondwana faunas in the close affinity of the Bothriolepis africana with B. barred of Antarctica, and the high diversity of groenlandaspid species, especially the presence of a very high crested form having affinities to Tiaraspis.
- Full Text: false
- Date Issued: 1997
On the life history of the lesser gurnard (Scorpaeniformes: Triglidae) inhabiting the Agulhas Bank, South Africa
- Authors: Booth, Anthony J
- Date: 1997
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125434 , vital:35782 , https://doi.10.1111/j.1095-8649.1997.tb01133.x
- Description: Fishes of the genus Labeo are widely distributed throughout Africa and consist of at least 80 species which comprise 16.4% of the African cyprinid ichthyofauna (Reid 1985). Most labeo species are also commercially important throughout the African continent, having contributed significantly to various fisheries. Their roe (sensu caviar) is often harvested as an additional bycatch (Skelton et al. 1991). Despite their obvious importance, the few studies that have investigated aspects of their life history have been conducted on the larger commercial species (Lowe 1952, Mulder 1973, Balon et al. 1974, Potgieter 1974, Baird 1976, Tomasson et al. 1984, van Zyl et al. 1995).
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- Date Issued: 1997
Petrology and geochemistry of peridotite xenoliths from the Letlhakane kimberlites, Botswana
- Authors: Stiefenhofer, Johann , Viljoen, K S , Marsh, Julian S
- Date: 1997
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149705 , vital:38876 , https://doi.org/10.1007/s004100050272
- Description: The diamondiferous Letlhakane kimberlites are intruded into the Proterozoic Magondi Belt of Botswana. Given the general correlation of diamondiferous kimberlites with Archaean cratons, the apparent tectonic setting of these kimberlites is somewhat anomalous. Xenoliths in kimberlite diatremes provide a window into the underlying crust and upper mantle and, with the aid of detailed petrological and geochemical study, can help unravel problems of tectonic setting.
- Full Text: false
- Date Issued: 1997
Photosensitization reactions of neodymium, dysprosium and lutetium diphthalocyanine
- Authors: Nensala, Ngudiankama , Nyokong, Tebello
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/${Handle} , vital:57084 , xlink:href="https://doi.org/10.1016/S0277-5387(97)00045-4"
- Description: Photolysis, using a visible radiation, of diphthalocyanine complexes of NdIII, DyIII and LuIII ([Pc(−2)NdIIIPc(−2)]−, [Pc(−2)DyIIIPc(−2)]− and [Pc(−2)LuIIIPc(−2)]−, respectively) in the presence of pentachlorophenol (PCP) or SO2 results in the one-electron oxidation of the diphthalocyanine species to Pc(−1)NdIIIPc(−2), Pc(−1)DyIIIPc(−2) and Pc(−2)LuIIIPc(−2), respectively. The PCP is reductively dechlorinated to tetra- and trichlorophenols. The quantum yields for the photosensitization reactions are of the order 10−4.
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- Date Issued: 1997
Redescription of three species of the genus Platypleura Amyot and Serville 1843 (Hemiptera Cicadidae)
- Authors: Villet, Martin H
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453827 , vital:75290 , https://doi.org/10.1080/03946975.1997.10539345
- Description: The type material of three platypleurine cicadas described by GERMAR (1834), Platypleura divisa, P. hirtipennis and P. plumosa, have been rediscovered and are redescribed to clarify their identity. Notes on their biology and biogeography are included.
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- Date Issued: 1997
Reflecting on socially transformative environmental literacy for Lesotho
- Authors: Mokuku, Tsepo , Lotz-Sisitka, Heila
- Date: 1997
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/438769 , vital:73498 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137444"
- Description: This paper is an attempt to clarify the concept of environmental literacy from a socially transformative orientation. It resulted from our ongoing reflection on a conceptual framework in and for a three-year research project on education for environmental literacy within the integrated science curriculum in Lesotho.
- Full Text:
- Date Issued: 1997