Petrology of the alkaline core of the Messum igneous complex, Namibia: evidence for the progressively decreasing effect of crustal contamination
- Harris, Chris, Marsh, Julian S, Milner, Simon C
- Authors: Harris, Chris , Marsh, Julian S , Milner, Simon C
- Date: 1999
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149746 , vital:38880 , https://doi.org/10.1093/petroj/40.9.1377
- Description: The Messum complex of NW Namibia, a part of the Paraná–Etendeka volcanic province, consists of a dominantly felsic central core, surrounded by older gabbros. The igneous rocks of the core can be divided, in order of decreasing age, into (1) a sub-alkaline suite, (2) an outer quartz syenite suite, and (3) an inner silica-undersaturated suite dominated by nepheline syenite. Compositional differences within the quartz syenite suite can be explained by fractional crystallization, but Sr- and O-isotope data indicate that these rocks contain a significant crustal component.
- Full Text: false
- Authors: Harris, Chris , Marsh, Julian S , Milner, Simon C
- Date: 1999
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149746 , vital:38880 , https://doi.org/10.1093/petroj/40.9.1377
- Description: The Messum complex of NW Namibia, a part of the Paraná–Etendeka volcanic province, consists of a dominantly felsic central core, surrounded by older gabbros. The igneous rocks of the core can be divided, in order of decreasing age, into (1) a sub-alkaline suite, (2) an outer quartz syenite suite, and (3) an inner silica-undersaturated suite dominated by nepheline syenite. Compositional differences within the quartz syenite suite can be explained by fractional crystallization, but Sr- and O-isotope data indicate that these rocks contain a significant crustal component.
- Full Text: false
Phoretic association of blackflies (Oiptera: Simuliidae) with heptageniid mayflies (Ephemeroptera: Heptageniidae) in South Africa
- Authors: de Moor, Ferdy C
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452172 , vital:75109 , https://journals.co.za/doi/pdf/10.10520/AJA10213589_400
- Description: The phoretic or epizoitic association of blackfly (Diptera: Simuliidae) larvae and pupae with other aquatic arthropods has been documented for a number of tropical African species (Grenier and Mouchet 1959; Corbet 1961, 1962; Germain et al. 1966; Disney 1969, 1971a-d, 1973; also references in Crosskey 1990). The significance of these associations has led to much speculation, although no scientific conclusions regarding the origin and purposes of the associations have been reached (Corbet 1961; Crosskey 1990).
- Full Text:
- Authors: de Moor, Ferdy C
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452172 , vital:75109 , https://journals.co.za/doi/pdf/10.10520/AJA10213589_400
- Description: The phoretic or epizoitic association of blackfly (Diptera: Simuliidae) larvae and pupae with other aquatic arthropods has been documented for a number of tropical African species (Grenier and Mouchet 1959; Corbet 1961, 1962; Germain et al. 1966; Disney 1969, 1971a-d, 1973; also references in Crosskey 1990). The significance of these associations has led to much speculation, although no scientific conclusions regarding the origin and purposes of the associations have been reached (Corbet 1961; Crosskey 1990).
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Re-evaluation of Ashton’s types of African cicadas (Homoptera Cicadidae).
- Authors: Villet, Martin H
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453840 , vital:75291 , https://doi.org/10.1080/03946975.1999.10539389
- Description: ASHTON (1914) described three species of cicada from Africa which were soon placed in synonymy with other species. Re-examination of the type material lead to the following revisions: Platypleura nigromarginata Ashton 1914 is removed from synonymy with Oxypleura quadraticollis (Butler 1874) and placed in the genus Strumoseura n. gen.; P. sikumba Ashton 1914 is confirmed as a junior synonym of Manza basimacula (Walker 1850) along with M. parva Villet 1989 n. syn.; and P. longirostris Ashton 1914 is removed from the synonymy of P. divisa Germar 1834.
- Full Text:
- Authors: Villet, Martin H
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453840 , vital:75291 , https://doi.org/10.1080/03946975.1999.10539389
- Description: ASHTON (1914) described three species of cicada from Africa which were soon placed in synonymy with other species. Re-examination of the type material lead to the following revisions: Platypleura nigromarginata Ashton 1914 is removed from synonymy with Oxypleura quadraticollis (Butler 1874) and placed in the genus Strumoseura n. gen.; P. sikumba Ashton 1914 is confirmed as a junior synonym of Manza basimacula (Walker 1850) along with M. parva Villet 1989 n. syn.; and P. longirostris Ashton 1914 is removed from the synonymy of P. divisa Germar 1834.
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Song sharing by neighbourhood groups of territorial male Blackeyed Bulbuls
- Lloyd, Penn, Hulley, Patrick E, Craig, Adrian J F K
- Authors: Lloyd, Penn , Hulley, Patrick E , Craig, Adrian J F K
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447841 , vital:74678 , https://doi.org/10.1080/00306525.1999.9634238
- Description: The territorial song of the Blackeyed Bulbul Pycnonotus barbatus is described for a population followed over two breeding seasons in suburban Grahamstown, South Africa. The Blackeyed Bulbul has a discrete and highly structured system of phrase sharing by neighbourhood groups of males. The most common repertoire size is five phrases (mean 5.5; range 2–9). In a temporally-stable song population, individual phrases are shared independently by discrete clusters of males. Neighbours show a strong tendency to share phrase types (but rarely whole repertoires), with overall song similarity decreasing rapidly with increasing distance between birds. This species is an ideal candidate for testing hypotheses concerning the adaptive value of song sharing by neighbourhood groups.
- Full Text:
- Authors: Lloyd, Penn , Hulley, Patrick E , Craig, Adrian J F K
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447841 , vital:74678 , https://doi.org/10.1080/00306525.1999.9634238
- Description: The territorial song of the Blackeyed Bulbul Pycnonotus barbatus is described for a population followed over two breeding seasons in suburban Grahamstown, South Africa. The Blackeyed Bulbul has a discrete and highly structured system of phrase sharing by neighbourhood groups of males. The most common repertoire size is five phrases (mean 5.5; range 2–9). In a temporally-stable song population, individual phrases are shared independently by discrete clusters of males. Neighbours show a strong tendency to share phrase types (but rarely whole repertoires), with overall song similarity decreasing rapidly with increasing distance between birds. This species is an ideal candidate for testing hypotheses concerning the adaptive value of song sharing by neighbourhood groups.
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The cicada genus Nyara n. gen. (Homoptera Cicadidae) systematics, behaviour and conservation status
- Authors: Villet, Martin H
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453870 , vital:75295 , https://doi.org/10.1080/03946975.1999.10539385
- Description: The cicada genus Nyara n. gen. and its sole species N. thanatotica n. sp. are described and diagnosed. This species is very peculiar because it often feigns death when disturbed. This is the first time such behaviour has been described in a cicada. Nyara is the third endemic cicada genus described from a South African forest. Its distribution along the subtropical Eastern Cape coast, which is threatened by strip mining and housing developments, highlights the need for conservation of these under-researched habitats.
- Full Text:
- Authors: Villet, Martin H
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453870 , vital:75295 , https://doi.org/10.1080/03946975.1999.10539385
- Description: The cicada genus Nyara n. gen. and its sole species N. thanatotica n. sp. are described and diagnosed. This species is very peculiar because it often feigns death when disturbed. This is the first time such behaviour has been described in a cicada. Nyara is the third endemic cicada genus described from a South African forest. Its distribution along the subtropical Eastern Cape coast, which is threatened by strip mining and housing developments, highlights the need for conservation of these under-researched habitats.
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The Development of a Generic Framework for the Implementation of Cheap, Component-Based Virtual Video-Conferencing System
- Panagou, Soteri, Bangay, Shaun D
- Authors: Panagou, Soteri , Bangay, Shaun D
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432824 , vital:72903 , https://www.cs.ru.ac.za/research/Groups/vrsig/pastprojects/014humanmodelling/paper03.pdf
- Description: We address the problem of virtual-videoconferencing. The proposed solution is effected in terms of a generic framework based on an in-house Virtual Reality system. The framework is composed of a number of distinct components: model acquisition, head tracking, expression analysis, network transmission and avatar reconstruction. The framework promises to provide a unique, cheap, and fast system for avatar construction, transmission and animation. This approach affords a conversion from the traditional video stream approach to the management of an avatar remotely and consequently makes minimal demands on network resources.
- Full Text:
- Authors: Panagou, Soteri , Bangay, Shaun D
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432824 , vital:72903 , https://www.cs.ru.ac.za/research/Groups/vrsig/pastprojects/014humanmodelling/paper03.pdf
- Description: We address the problem of virtual-videoconferencing. The proposed solution is effected in terms of a generic framework based on an in-house Virtual Reality system. The framework is composed of a number of distinct components: model acquisition, head tracking, expression analysis, network transmission and avatar reconstruction. The framework promises to provide a unique, cheap, and fast system for avatar construction, transmission and animation. This approach affords a conversion from the traditional video stream approach to the management of an avatar remotely and consequently makes minimal demands on network resources.
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The market for commercial farm land in the Eastern Cape Province of South Africa as a means of redistribution:
- Antrobus, Geoffrey G, Fraser, Gavin C G
- Authors: Antrobus, Geoffrey G , Fraser, Gavin C G
- Date: 1999
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143024 , vital:38194 , DOI: 10.4314/rosas.v3i1.22991
- Description: The election promise of the majority party in the new South African government was to redistribute 30% of the agricultural land in the hands of Whites within a period of 5 years. Transfers of land in the Eastern Cape Province are examined as a case study. While 60% of the total number of Eastern Cape farms changed hands over 5 years, these constituted only 19% of the surface area. A large proportion of rural transfers were small (less than 5 hectares) peri-urban properties which cannot all be considered as viable farming units. At average prices about R1 to R2 billion would be required to establish new farmers on land with the necessary livestock, machinery and equipment. Resource poor new entrants would need a major state contribution to make initial entry and subsequent survival feasible. To achieve their goal through market transfers the government would need to either substantially lengthen its time horizon or lower its target.
- Full Text:
- Authors: Antrobus, Geoffrey G , Fraser, Gavin C G
- Date: 1999
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143024 , vital:38194 , DOI: 10.4314/rosas.v3i1.22991
- Description: The election promise of the majority party in the new South African government was to redistribute 30% of the agricultural land in the hands of Whites within a period of 5 years. Transfers of land in the Eastern Cape Province are examined as a case study. While 60% of the total number of Eastern Cape farms changed hands over 5 years, these constituted only 19% of the surface area. A large proportion of rural transfers were small (less than 5 hectares) peri-urban properties which cannot all be considered as viable farming units. At average prices about R1 to R2 billion would be required to establish new farmers on land with the necessary livestock, machinery and equipment. Resource poor new entrants would need a major state contribution to make initial entry and subsequent survival feasible. To achieve their goal through market transfers the government would need to either substantially lengthen its time horizon or lower its target.
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The power behind the scenes: the Afrikaner Nationalist Women's Parties, 1915 to 1931.
- Authors: Vincent, Louise
- Date: 1999
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141795 , vital:38005 , DOI: 10.1080/02582479908671348
- Description: The Enlightenment expectation was that political identity based on ethnic nationalist sentiments would gradually give way to more ‘rational’ forms of association. That expectation has, in the late twentieth century, proved somewhat premature. The explosion of ethnic nationalist conflicts onto the international stage in the post-Cold War era has brought with it a renewed intellectual interest in the politics of nationalism and ethnicity. In response to the need for new avenues of inquiry amidst a vast and growing literature, Anthony Smith’s work on national identity appeals for a research agenda which treats nations and nationalism as cultural phenomena as well as forms of politics.
- Full Text:
- Authors: Vincent, Louise
- Date: 1999
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141795 , vital:38005 , DOI: 10.1080/02582479908671348
- Description: The Enlightenment expectation was that political identity based on ethnic nationalist sentiments would gradually give way to more ‘rational’ forms of association. That expectation has, in the late twentieth century, proved somewhat premature. The explosion of ethnic nationalist conflicts onto the international stage in the post-Cold War era has brought with it a renewed intellectual interest in the politics of nationalism and ethnicity. In response to the need for new avenues of inquiry amidst a vast and growing literature, Anthony Smith’s work on national identity appeals for a research agenda which treats nations and nationalism as cultural phenomena as well as forms of politics.
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The Virtual Remote Control-An Extensible, Virtual Reality, User Interface Device
- Rorke, Michael, Bangay, Shaun D
- Authors: Rorke, Michael , Bangay, Shaun D
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432743 , vital:72896 , https://www.cs.ru.ac.za/research/Groups/vrsig/pastprojects/013interaction/paper02.pdf
- Description: Immersive virtual reality (VR) places the user inside of the computing envi-ronment, blurring the distinction between the environment itself and the user interface to access that environment non-obvious. This lack of distinction between environment and interface makes it difficult to place menus and other interface elements where the user is both able to access them easily and where they do not obscure large parts of the users field of view. We propose a system called the 'Virtual Remote Control' (VRC). The VRC con-sists of a physical device (a small touchpad tracked using a Polhemus In-sideTrak magnetic tracker) which the user is able to hold and for which there is a representation in the virtual environment. The VRC is represented in the environment by a virtual menu. The user is able to make selections from the virtual menu by moving their finger around the touch pad part of the VRC and 'tapping' on the required action. Additionally, the user is able to select an object for the action to be applied on, by 'pointing' the representa-tion of the VRC at the object-as one would point a remote control at a Hi-fi of TV set.
- Full Text:
- Authors: Rorke, Michael , Bangay, Shaun D
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432743 , vital:72896 , https://www.cs.ru.ac.za/research/Groups/vrsig/pastprojects/013interaction/paper02.pdf
- Description: Immersive virtual reality (VR) places the user inside of the computing envi-ronment, blurring the distinction between the environment itself and the user interface to access that environment non-obvious. This lack of distinction between environment and interface makes it difficult to place menus and other interface elements where the user is both able to access them easily and where they do not obscure large parts of the users field of view. We propose a system called the 'Virtual Remote Control' (VRC). The VRC con-sists of a physical device (a small touchpad tracked using a Polhemus In-sideTrak magnetic tracker) which the user is able to hold and for which there is a representation in the virtual environment. The VRC is represented in the environment by a virtual menu. The user is able to make selections from the virtual menu by moving their finger around the touch pad part of the VRC and 'tapping' on the required action. Additionally, the user is able to select an object for the action to be applied on, by 'pointing' the representa-tion of the VRC at the object-as one would point a remote control at a Hi-fi of TV set.
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Thermoregulatory capabilities of the woodland dormouse, Graphiurus murinus
- Whittington-Jones, Craig A, Brown, C R
- Authors: Whittington-Jones, Craig A , Brown, C R
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447349 , vital:74613 , https://doi.org/10.1080/02541858.1999.11448485
- Description: The woodland dormouse, Graphiurus murinus, in common with many other small rodents, enters torpor under conditions of food deprivation and low temperatures. Its thermoregulatory capabilities under more favourable conditions, however, have not been investigated. We measured metabolism and thermoregulation in woodland dormice acclimated to long-day length, moderate temperature and abundant food over a temperature range (Ta) of approximately 5–37°C. The thermal neutral zone for this species lay between 29 and 35°C. Estimated resting metabolic rate (RMR) within this range averaged 21.10 ± 3.28 J g-1 h-1.
- Full Text:
- Authors: Whittington-Jones, Craig A , Brown, C R
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447349 , vital:74613 , https://doi.org/10.1080/02541858.1999.11448485
- Description: The woodland dormouse, Graphiurus murinus, in common with many other small rodents, enters torpor under conditions of food deprivation and low temperatures. Its thermoregulatory capabilities under more favourable conditions, however, have not been investigated. We measured metabolism and thermoregulation in woodland dormice acclimated to long-day length, moderate temperature and abundant food over a temperature range (Ta) of approximately 5–37°C. The thermal neutral zone for this species lay between 29 and 35°C. Estimated resting metabolic rate (RMR) within this range averaged 21.10 ± 3.28 J g-1 h-1.
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Transformational leadership and organisational effectiveness in the administration of cricket in South Africa
- Authors: Amos, Trevor L
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270958 , vital:54495 , xlink:href="https://hdl.handle.net/10520/EJC-682622887"
- Description: After years of isolation from the international sporting arena, South African sports teams have recently achieved much success. This article is concerned specifically with managing for organisational effectiveness in South African cricket According to the theory of transformational leadership, there should be a positive relationship between this style of leadership and organisational effectiveness. The Multifactor Leadership Questionnaire was used to collect information about leadership while data for organisational effectiveness, the dependent variable, was collected using the Effectiveness Survey for Cricket Administration. Most of the results regarding the relationship of the transformational leadership factors and organisational effectiveness were significant. On the other hand, most of the results regarding the relationship of the transactional leadership factors and organisational effectiveness were not significant. The overall results provide general support of Bass' (1990) argument of the universal application of the transformational leadership theory.
- Full Text:
- Authors: Amos, Trevor L
- Date: 1999
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270958 , vital:54495 , xlink:href="https://hdl.handle.net/10520/EJC-682622887"
- Description: After years of isolation from the international sporting arena, South African sports teams have recently achieved much success. This article is concerned specifically with managing for organisational effectiveness in South African cricket According to the theory of transformational leadership, there should be a positive relationship between this style of leadership and organisational effectiveness. The Multifactor Leadership Questionnaire was used to collect information about leadership while data for organisational effectiveness, the dependent variable, was collected using the Effectiveness Survey for Cricket Administration. Most of the results regarding the relationship of the transformational leadership factors and organisational effectiveness were significant. On the other hand, most of the results regarding the relationship of the transactional leadership factors and organisational effectiveness were not significant. The overall results provide general support of Bass' (1990) argument of the universal application of the transformational leadership theory.
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Ecological and morphological differentiation of the honeybees. Apis mellitera linnaeus (Hymenoptera: Apidae). of West Africa
- Radloff, Sarah E, Hepburn, H Randall, Fuchs, S
- Authors: Radloff, Sarah E , Hepburn, H Randall , Fuchs, S
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451832 , vital:75080 , https://hdl.handle.net/10520/AJA10213589_253
- Description: Morphometric characters of worker honeybees, Apis mellifera Linnaeus, were analysed by multivariate methods to characterize their populations in the sahelian, dry and wet tropical and equatorial regions of western and eastern Africa (mainly between 0 and 15 N latitude, 18 W and 39""E longitude). Two distinct morphocIusters and azoneof hybridization between them were identified. The bees are identified as Apis mellifera adansonii Latreille and A. m. jemenitica Ruttrter. The former subspecies is distributed in the equatorial and wet tropical regions, the latter in the dry tropical and sahelian eco-climatic zones. The hybrid zone extends into the two tropical and savanna biomes and it is suggested that the stability of the hybridization zone is largely the effect of extensive annual fire in the region.
- Full Text:
- Authors: Radloff, Sarah E , Hepburn, H Randall , Fuchs, S
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451832 , vital:75080 , https://hdl.handle.net/10520/AJA10213589_253
- Description: Morphometric characters of worker honeybees, Apis mellifera Linnaeus, were analysed by multivariate methods to characterize their populations in the sahelian, dry and wet tropical and equatorial regions of western and eastern Africa (mainly between 0 and 15 N latitude, 18 W and 39""E longitude). Two distinct morphocIusters and azoneof hybridization between them were identified. The bees are identified as Apis mellifera adansonii Latreille and A. m. jemenitica Ruttrter. The former subspecies is distributed in the equatorial and wet tropical regions, the latter in the dry tropical and sahelian eco-climatic zones. The hybrid zone extends into the two tropical and savanna biomes and it is suggested that the stability of the hybridization zone is largely the effect of extensive annual fire in the region.
- Full Text: