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:
- Date Issued: 1999
- 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:
- Date Issued: 1999
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:
- Date Issued: 1999
- 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:
- Date Issued: 1999
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:
- Date Issued: 1999
- 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:
- Date Issued: 1999
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:
- Date Issued: 1999
- 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:
- Date Issued: 1999
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:
- Date Issued: 1999
- 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:
- Date Issued: 1999
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:
- Date Issued: 1999
- 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:
- Date Issued: 1999
"We're just teaching in a vacuum". Teaching in context in the learning for sustainability project
- Authors: Janse van Rensburg, Eureta
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/438817 , vital:73502 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137417"
- Description: Learning for Sustainability is a Danish-funded project for supporting teachers in environmental education curriculum development, in the Departments of Education in the Gauteng and Mpumalanga provinces of South Africa. The Rhodes University Environmental Education Unit is responsible for its evaluation. Instead of establishing baseline data against which to compare the project outcomes, the researchers are developing contextual profiles towards a deepening understanding of the contexts in which the teachers work, and to judge the appropriateness of project activities. This paper introduces insights from the developing profile based on questionnaires; interviews; observations during project meetings and school visits; and document analysis. The emerging issues pertain to curriculum and professional development in environmental education, within the context of educational policy transformation. In particular the paper highlights the role of context in responsive reform initiatives.
- Full Text:
- Date Issued: 1998
- Authors: Janse van Rensburg, Eureta
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/438817 , vital:73502 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137417"
- Description: Learning for Sustainability is a Danish-funded project for supporting teachers in environmental education curriculum development, in the Departments of Education in the Gauteng and Mpumalanga provinces of South Africa. The Rhodes University Environmental Education Unit is responsible for its evaluation. Instead of establishing baseline data against which to compare the project outcomes, the researchers are developing contextual profiles towards a deepening understanding of the contexts in which the teachers work, and to judge the appropriateness of project activities. This paper introduces insights from the developing profile based on questionnaires; interviews; observations during project meetings and school visits; and document analysis. The emerging issues pertain to curriculum and professional development in environmental education, within the context of educational policy transformation. In particular the paper highlights the role of context in responsive reform initiatives.
- Full Text:
- Date Issued: 1998
An investigation into factors influencing immersion in interactive virtual reality environments
- Bangay, Shaun D, Preston, Louise
- Authors: Bangay, Shaun D , Preston, Louise
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432864 , vital:72908 , https://pubmed.ncbi.nlm.nih.gov/10350927/
- Description: Two interactive virtual reality environments were used to identify factors that may affect, or be affected by, the degree of immersion in a virtual world. In particular, the level of stress in a "swimming with dolphins" simulation is measured, as is the degree of simulator sickness resulting form a virtual roller coaster. Analysis of the results indicates that a relationship between the degree of immersion and the following factors: excitement, comfort, quality and age. The following factors are found to depend on the degree of immersion: simulator sickness, control, excitement and desire to repeat the experience.
- Full Text:
- Date Issued: 1998
- Authors: Bangay, Shaun D , Preston, Louise
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432864 , vital:72908 , https://pubmed.ncbi.nlm.nih.gov/10350927/
- Description: Two interactive virtual reality environments were used to identify factors that may affect, or be affected by, the degree of immersion in a virtual world. In particular, the level of stress in a "swimming with dolphins" simulation is measured, as is the degree of simulator sickness resulting form a virtual roller coaster. Analysis of the results indicates that a relationship between the degree of immersion and the following factors: excitement, comfort, quality and age. The following factors are found to depend on the degree of immersion: simulator sickness, control, excitement and desire to repeat the experience.
- Full Text:
- Date Issued: 1998
An Investigation into the feasibility of Human Facial Modeling
- Panagou, Sotcri, Bangay, Shaun D
- Authors: Panagou, Sotcri , Bangay, Shaun D
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432711 , vital:72894 , https://citeseerx.ist.psu.edu/document?repid=rep1ype=pdfoi=c305c27d16322208e0e6815ca261d61019a4cbd0
- Description: In this paper, virtual videoconferencing is investigated. The goal of the project is to develop a cheap, realistic yet real-time 3D face-modeling tool using a number of camera feeds. Bandwidth utilisation can then be minimised by transferring only the actual model (and subsequently, changes to the model) of the actor's face. Using a virtual reality system, reconstruction of a human face is performed and transmitted, thereby reducing bandwidth requirements. The modeling process is discussed, with results.
- Full Text:
- Date Issued: 1998
- Authors: Panagou, Sotcri , Bangay, Shaun D
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432711 , vital:72894 , https://citeseerx.ist.psu.edu/document?repid=rep1ype=pdfoi=c305c27d16322208e0e6815ca261d61019a4cbd0
- Description: In this paper, virtual videoconferencing is investigated. The goal of the project is to develop a cheap, realistic yet real-time 3D face-modeling tool using a number of camera feeds. Bandwidth utilisation can then be minimised by transferring only the actual model (and subsequently, changes to the model) of the actor's face. Using a virtual reality system, reconstruction of a human face is performed and transmitted, thereby reducing bandwidth requirements. The modeling process is discussed, with results.
- Full Text:
- Date Issued: 1998
Annotated records of blackfly (Diptera: Simuliidae) distribution in southern Africa
- Palmer, R W, de Moor, Ferdy C
- Authors: Palmer, R W , de Moor, Ferdy C
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452114 , vital:75104 , https://hdl.handle.net/10520/AJA10213589_229
- Description: Regional and catchment distributions of blackflies (Diptera: Simuliidae) in southern Africa are presented and discussed relative to the biology and environmental preferences of the aquatic stages. Distribution data are based on all known records, both published and unpublished. Thirty nine blackfly species are recorded: 13 are widespread with no particular geographical affinities, 18 are restricted in distribution and eight are rare. Distributions are closely related to downstream changes in rivers, although eight species are endemic to parts of the southern and southwestern Cape, while eight are absent from the southern and southwestern Cape.
- Full Text:
- Date Issued: 1998
- Authors: Palmer, R W , de Moor, Ferdy C
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452114 , vital:75104 , https://hdl.handle.net/10520/AJA10213589_229
- Description: Regional and catchment distributions of blackflies (Diptera: Simuliidae) in southern Africa are presented and discussed relative to the biology and environmental preferences of the aquatic stages. Distribution data are based on all known records, both published and unpublished. Thirty nine blackfly species are recorded: 13 are widespread with no particular geographical affinities, 18 are restricted in distribution and eight are rare. Distributions are closely related to downstream changes in rivers, although eight species are endemic to parts of the southern and southwestern Cape, while eight are absent from the southern and southwestern Cape.
- Full Text:
- Date Issued: 1998
Clinal morphometric variation in wild honey bees (Hymenoptera: Apidae) in South Africa
- Steele, G R, Villet, Martin H, Radloff, Sarah E, Hepburn, H Randall
- Authors: Steele, G R , Villet, Martin H , Radloff, Sarah E , Hepburn, H Randall
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442622 , vital:74015 , https://www.jstor.org/stable/2999809
- Description: As a result of side effects of the accidental dispersal of the Cape honey bee, it has become of agroeconomic importance to delineate the region within South Africa where thelytokous worker honey bees occur so that apicultural movement of bees does not exacerbate the problem. Thelytokous workers are believed to be unique to Apis mellifera capensis, so that the problem is to find morphological markers distinguishing this race from its A. m. scutellata neighbours. However, no evidence of the expected hybrid zone demarcating races could be found. Factor analysis revealed only one spherical cluster of samples. Trend surfaces of the local mean morphometric factor scores showed a cline that paralleled latitude, with distortions relating to montane and continental effects. Discriminant function analysis implicated certain mountain ranges in amplifying the effects of latitude. Trend surfaces of local intercolony factor variance showed morphometric homogeneity across most of the country. We conclude that there is only a single population of honey bees in South Africa, and that it shows climate-correlated clinal variation. If the transportation of bees for commercial apiculture is to be successfully regulated to solve the `capensis calamity', further research should focus on the geographical distribution of thelytokous workers rather than on the capensis phenotype. Such workers have a wider distribution than capensis, occurring also at high frequencies around the type locality of A. m. scutellata.
- Full Text:
- Date Issued: 1998
- Authors: Steele, G R , Villet, Martin H , Radloff, Sarah E , Hepburn, H Randall
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442622 , vital:74015 , https://www.jstor.org/stable/2999809
- Description: As a result of side effects of the accidental dispersal of the Cape honey bee, it has become of agroeconomic importance to delineate the region within South Africa where thelytokous worker honey bees occur so that apicultural movement of bees does not exacerbate the problem. Thelytokous workers are believed to be unique to Apis mellifera capensis, so that the problem is to find morphological markers distinguishing this race from its A. m. scutellata neighbours. However, no evidence of the expected hybrid zone demarcating races could be found. Factor analysis revealed only one spherical cluster of samples. Trend surfaces of the local mean morphometric factor scores showed a cline that paralleled latitude, with distortions relating to montane and continental effects. Discriminant function analysis implicated certain mountain ranges in amplifying the effects of latitude. Trend surfaces of local intercolony factor variance showed morphometric homogeneity across most of the country. We conclude that there is only a single population of honey bees in South Africa, and that it shows climate-correlated clinal variation. If the transportation of bees for commercial apiculture is to be successfully regulated to solve the `capensis calamity', further research should focus on the geographical distribution of thelytokous workers rather than on the capensis phenotype. Such workers have a wider distribution than capensis, occurring also at high frequencies around the type locality of A. m. scutellata.
- Full Text:
- Date Issued: 1998
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:
- Date Issued: 1998
- 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:
- Date Issued: 1998
Editorial
- Authors: Irwin, Patrick R
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/438730 , vital:73495 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137406"
- Description: The 1998 EEASA Conference-and-Workshops meeting was a sound success. The Botswana organisers must be congratulated on convening such a convivial and stimulating event. The conference gave exposure to some of the environmental education research in progress in the region. While there is an exciting level of regional research activity, this is not adequately represented in the Southern African Journal of Environmental Education, or any other published forum for that matter. The SAJEE receives a rather small number of research papers from southern Africans for review; in addition the journal's referees and editors judge an even smaller number of these as suitable for publication. What this reflects, inter alia, is the need for environmental educators in the region to write more vigorously about their research.
- Full Text:
- Date Issued: 1998
- Authors: Irwin, Patrick R
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/438730 , vital:73495 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137406"
- Description: The 1998 EEASA Conference-and-Workshops meeting was a sound success. The Botswana organisers must be congratulated on convening such a convivial and stimulating event. The conference gave exposure to some of the environmental education research in progress in the region. While there is an exciting level of regional research activity, this is not adequately represented in the Southern African Journal of Environmental Education, or any other published forum for that matter. The SAJEE receives a rather small number of research papers from southern Africans for review; in addition the journal's referees and editors judge an even smaller number of these as suitable for publication. What this reflects, inter alia, is the need for environmental educators in the region to write more vigorously about their research.
- Full Text:
- Date Issued: 1998
In vitro release of amoxycillin from lipophilic suppositories
- Webster, Jessica A, Dowse, Roslind, Walker, Roderick B
- Authors: Webster, Jessica A , Dowse, Roslind , Walker, Roderick B
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184377 , vital:44213 , xlink:href="https://doi.org/10.3109/03639049809085636"
- Description: The in vitro release characteristics of amoxycillin from different lipophilic suppository bases were investigated using the USP rotating basket method. Suppositories containing 250 mg amoxycillin were prepared in theobroma oil and in the semisynthetic bases Witepsol W35, Suppocire A32, Novata BD, and Novata 299. Both freshly prepared and 1-month-old suppositories were tested. Analysis of amoxycillin was performed using a validated high-performance liquid chromatographic (HPLC) technique. Release profiles differed significantly between bases, with the greatest amount of amoxycillin being released from both newly made and 1-month-old Novata BD bases (87.57 ± 8.18 and 99.66 ± 6.63%, respectively), and the lowest amount released from the newly manufactured theobroma suppositories (8.82 ± 0.75%) and the 1-month-old Suppocire A32 suppositories (7.78 ± 0.27%).
- Full Text:
- Date Issued: 1998
- Authors: Webster, Jessica A , Dowse, Roslind , Walker, Roderick B
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184377 , vital:44213 , xlink:href="https://doi.org/10.3109/03639049809085636"
- Description: The in vitro release characteristics of amoxycillin from different lipophilic suppository bases were investigated using the USP rotating basket method. Suppositories containing 250 mg amoxycillin were prepared in theobroma oil and in the semisynthetic bases Witepsol W35, Suppocire A32, Novata BD, and Novata 299. Both freshly prepared and 1-month-old suppositories were tested. Analysis of amoxycillin was performed using a validated high-performance liquid chromatographic (HPLC) technique. Release profiles differed significantly between bases, with the greatest amount of amoxycillin being released from both newly made and 1-month-old Novata BD bases (87.57 ± 8.18 and 99.66 ± 6.63%, respectively), and the lowest amount released from the newly manufactured theobroma suppositories (8.82 ± 0.75%) and the 1-month-old Suppocire A32 suppositories (7.78 ± 0.27%).
- Full Text:
- Date Issued: 1998
Interaction of nitric oxide with cobalt (II) phthalocyanine
- Vilakazi, Sibulelo L, Nyokong, Tebello
- Authors: Vilakazi, Sibulelo L , Nyokong, Tebello
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293579 , vital:57100 , xlink:href="https://doi.org/10.1016/S0277-5387(98)00244-7"
- Description: The coordination of nitric oxide (NO) to cobalt(II) phthalocyanine (CoPc) in dimethyl sulphoxide (DMSO) has been studied. CoPc coordinates with NO in a 1:1 ratio, forming a CoPc(NO) species. The IR band observed at 1680 cm−1 is assigned to the coordinated NO. In the presence of excess NO, pseudo first order kinetics were followed. The observed rate constant, kf, was determined to be 15.0±0.3 dm−3 mol−1 s−1 and the equilibrium constant was K=5.4±0.4×104dm3 mol−1. Solution or adsorbed CoPc catalyses the reduction of NO. The products of reduction include NH3 and NH2OH.
- Full Text:
- Date Issued: 1998
- Authors: Vilakazi, Sibulelo L , Nyokong, Tebello
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293579 , vital:57100 , xlink:href="https://doi.org/10.1016/S0277-5387(98)00244-7"
- Description: The coordination of nitric oxide (NO) to cobalt(II) phthalocyanine (CoPc) in dimethyl sulphoxide (DMSO) has been studied. CoPc coordinates with NO in a 1:1 ratio, forming a CoPc(NO) species. The IR band observed at 1680 cm−1 is assigned to the coordinated NO. In the presence of excess NO, pseudo first order kinetics were followed. The observed rate constant, kf, was determined to be 15.0±0.3 dm−3 mol−1 s−1 and the equilibrium constant was K=5.4±0.4×104dm3 mol−1. Solution or adsorbed CoPc catalyses the reduction of NO. The products of reduction include NH3 and NH2OH.
- Full Text:
- Date Issued: 1998
Patterns of marine harvest effort in southwestern New Georgia, Solomon Islands: resource management or optimal foraging?
- Authors: Shankar, Aswani
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439971 , vital:73724 , xlink:href="https://doi.org/10.1016/S0964-5691(98)00047-7"
- Description: Numerous researchers in the field of maritime anthropology have accepted the notion that marine tenure institutions are cultural systems designed to conserve marine resources. This idea has attained wide acceptance without the development of an ecological model to account for the occurrence of conservation and/or depletion of resources. In this study, foraging theory is offered as an alternative theoretical framework to examine the diversity of human resource exploitation strategies in coastal ecosystems. The results generated by the foraging models are considered here in relation to their significance in linking ecological evolutionary approaches in anthropology with coastal resource management.
- Full Text:
- Date Issued: 1998
- Authors: Shankar, Aswani
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439971 , vital:73724 , xlink:href="https://doi.org/10.1016/S0964-5691(98)00047-7"
- Description: Numerous researchers in the field of maritime anthropology have accepted the notion that marine tenure institutions are cultural systems designed to conserve marine resources. This idea has attained wide acceptance without the development of an ecological model to account for the occurrence of conservation and/or depletion of resources. In this study, foraging theory is offered as an alternative theoretical framework to examine the diversity of human resource exploitation strategies in coastal ecosystems. The results generated by the foraging models are considered here in relation to their significance in linking ecological evolutionary approaches in anthropology with coastal resource management.
- Full Text:
- Date Issued: 1998
Photoassisted reduction of thionyl chloride by neodymium, europium, thulium and lutetium diphthalocyanines
- Nensala, Ngudiankama, Nyokong, Tebello
- Authors: Nensala, Ngudiankama , Nyokong, Tebello
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293590 , vital:57101 , xlink:href="https://doi.org/10.1016/S0277-5387(98)00133-8"
- Description: Diphthalocyanine complexes of Nd III, EuIII, TmIII and LuIII ( [Pc (−2) Nd IIIPc (−2) ] −, [Pc (−2) EuIIIPc (−2) ] −, [Pc (−2) TmIIIPc (−2) ] − and [Pc (−2) LuIIIPc (−2) ] −, respectively) , undergo one or two-electron oxidation in the presence of thionyl chloride. The oxidation products depend on the concentration of the thionyl chloride. At low concentrations of SOCl2 (larger than 10−4 mol dm−3) one-electron oxidation occurs only upon photolysis, giving the neutral lanthanide diphthalocyanine, Pc (−2) LnPc (−1) , complexes. The Pc (−2) LnPc (−1) species undergo one-electron photooxidation to the [Pc (−1) LnPc (−1) ] + in dichloromethane and in the presence of SOCl2. At large concentrations of SOCl2 (>10−2 mol dm−3) , two electron oxidation of the [Pc (−2) LnPc (−2) ] − species directly to [Pc (−1) LnPc (−1) ] + occurs.
- Full Text:
- Date Issued: 1998
- Authors: Nensala, Ngudiankama , Nyokong, Tebello
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293590 , vital:57101 , xlink:href="https://doi.org/10.1016/S0277-5387(98)00133-8"
- Description: Diphthalocyanine complexes of Nd III, EuIII, TmIII and LuIII ( [Pc (−2) Nd IIIPc (−2) ] −, [Pc (−2) EuIIIPc (−2) ] −, [Pc (−2) TmIIIPc (−2) ] − and [Pc (−2) LuIIIPc (−2) ] −, respectively) , undergo one or two-electron oxidation in the presence of thionyl chloride. The oxidation products depend on the concentration of the thionyl chloride. At low concentrations of SOCl2 (larger than 10−4 mol dm−3) one-electron oxidation occurs only upon photolysis, giving the neutral lanthanide diphthalocyanine, Pc (−2) LnPc (−1) , complexes. The Pc (−2) LnPc (−1) species undergo one-electron photooxidation to the [Pc (−1) LnPc (−1) ] + in dichloromethane and in the presence of SOCl2. At large concentrations of SOCl2 (>10−2 mol dm−3) , two electron oxidation of the [Pc (−2) LnPc (−2) ] − species directly to [Pc (−1) LnPc (−1) ] + occurs.
- Full Text:
- Date Issued: 1998
Sexual dimorphism and tail-length in widowbirds and bishopbirds (Ploeeidae: Euplectes spp.): a reassessment
- Craig, Adrian J F K, Villet, Martin H
- Authors: Craig, Adrian J F K , Villet, Martin H
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442306 , vital:73974 , https://doi.org/10.1111/j.1474-919X.1998.tb04551.x
- Description: No evidence for sexual selection in the evolution of tail‐length or wing‐length in widow birds and bishopbirds (genus Euplectes) was found when the methods used by previous authors were applied to a larger set of data. Nuptial tail‐length dimorphism scaled with body size dimorphism except in Euplectes progne, and interpopulation variation in taillength could be explained by genetic drift alone. Wing‐length appears to be under stabilizing selection and scales allometrically with body size, with no relation to tail‐length unless E. progne is included in the analysis.
- Full Text:
- Date Issued: 1998
- Authors: Craig, Adrian J F K , Villet, Martin H
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442306 , vital:73974 , https://doi.org/10.1111/j.1474-919X.1998.tb04551.x
- Description: No evidence for sexual selection in the evolution of tail‐length or wing‐length in widow birds and bishopbirds (genus Euplectes) was found when the methods used by previous authors were applied to a larger set of data. Nuptial tail‐length dimorphism scaled with body size dimorphism except in Euplectes progne, and interpopulation variation in taillength could be explained by genetic drift alone. Wing‐length appears to be under stabilizing selection and scales allometrically with body size, with no relation to tail‐length unless E. progne is included in the analysis.
- Full Text:
- Date Issued: 1998
Spatial and temporal variability in recruitment of intertidal mussels around the coast of southern Africa
- Harris, Jean M, Branch, George M, Elliot, Bridget L, Currie, Bronwen, Dye, Arthur H, McQuaid, Christopher D, Tomalin, Bruce J, Velasquez, Claudio
- Authors: Harris, Jean M , Branch, George M , Elliot, Bridget L , Currie, Bronwen , Dye, Arthur H , McQuaid, Christopher D , Tomalin, Bruce J , Velasquez, Claudio
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447579 , vital:74658 , https://www.ajol.info/index.php/az/article/view/154717
- Description: Intensity of intertidal mussel recruitment was compared across a range of different spatial and temporal scales around the coast of southern Africa between June 1995 and October 1996. Comparison of the east and west coasts revealed significantly higher recruit densities on the west coast, corresponding to larger adult densities. This difference between the two coasts reflects biogeographic disparities in mussel species composition, growth rates and spawning intensities, oceanographic conditions and productivity. Significant spatial variations in recruitment were recorded between regions 100–1000 km apart and between localities 1–25 km apart. Results suggest that the influence of dispersal processes on recruitment patterns acts at a relatively small scale, and may affect the distribution and abundance of adults among shores only a few kilometres apart.
- Full Text:
- Date Issued: 1998
- Authors: Harris, Jean M , Branch, George M , Elliot, Bridget L , Currie, Bronwen , Dye, Arthur H , McQuaid, Christopher D , Tomalin, Bruce J , Velasquez, Claudio
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447579 , vital:74658 , https://www.ajol.info/index.php/az/article/view/154717
- Description: Intensity of intertidal mussel recruitment was compared across a range of different spatial and temporal scales around the coast of southern Africa between June 1995 and October 1996. Comparison of the east and west coasts revealed significantly higher recruit densities on the west coast, corresponding to larger adult densities. This difference between the two coasts reflects biogeographic disparities in mussel species composition, growth rates and spawning intensities, oceanographic conditions and productivity. Significant spatial variations in recruitment were recorded between regions 100–1000 km apart and between localities 1–25 km apart. Results suggest that the influence of dispersal processes on recruitment patterns acts at a relatively small scale, and may affect the distribution and abundance of adults among shores only a few kilometres apart.
- Full Text:
- Date Issued: 1998
The biology of Tilapia rendalli and Oreochromis mossambicus (Pisces: Cichlidae) in a subtropical lake in Mozambique
- Weyl, Olaf L F, Hecht, Thomas
- Authors: Weyl, Olaf L F , Hecht, Thomas
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446944 , vital:74572 , https://www.ajol.info/index.php/az/article/view/154744
- Description: This study of age and growth, reproduction and juvenile recruitment of Tilapia rendalli and Oreochromis mossambicus was undertaken in Lake Chicamba, a large, clear subtropical lake in central Mozambique. Sectioned otoliths were used to estimate age. Marginal zone analysis showed that annulus formation occurred during winter, in July and August. Maximum age estimates for T. rendalli and O. mossambicus were 16 and 10 years, respectively. Growth was described by the 3 parameter von Bertalanffy model as Lt= 238.74 (1-e-0,636 (1+ 00905)) mm TL for T. rendalli and Lt= 266.06 (1-e-0 70904 (1+ 0269)) mm TL for O. mossambicus. The length-at-50% maturity (Lm 50) of male T. rendalli was 218 mm total lenglh (TL) and 205 mm TL in females. In O. mossambicus the Lm 50 for males was 251 mm TL and for females 223 mm TL. Both species spawned throughout summer. Lake level was found to have no effect on spawning periodicity although recruitment was flood dependent.
- Full Text:
- Date Issued: 1998
- Authors: Weyl, Olaf L F , Hecht, Thomas
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446944 , vital:74572 , https://www.ajol.info/index.php/az/article/view/154744
- Description: This study of age and growth, reproduction and juvenile recruitment of Tilapia rendalli and Oreochromis mossambicus was undertaken in Lake Chicamba, a large, clear subtropical lake in central Mozambique. Sectioned otoliths were used to estimate age. Marginal zone analysis showed that annulus formation occurred during winter, in July and August. Maximum age estimates for T. rendalli and O. mossambicus were 16 and 10 years, respectively. Growth was described by the 3 parameter von Bertalanffy model as Lt= 238.74 (1-e-0,636 (1+ 00905)) mm TL for T. rendalli and Lt= 266.06 (1-e-0 70904 (1+ 0269)) mm TL for O. mossambicus. The length-at-50% maturity (Lm 50) of male T. rendalli was 218 mm total lenglh (TL) and 205 mm TL in females. In O. mossambicus the Lm 50 for males was 251 mm TL and for females 223 mm TL. Both species spawned throughout summer. Lake level was found to have no effect on spawning periodicity although recruitment was flood dependent.
- Full Text:
- Date Issued: 1998