An investigation into the bacterial diversity associated with South African latrunculid sponges that produce bioactive secondary metabolites
- Authors: Walmsley, Tara Aisling
- Date: 2014
- Subjects: Sponges -- South Africa -- Algoa Bay , Sponges -- Classification , Metabolites -- South Africa -- Algoa Bay , Marine metabolites -- South Africa -- Algoa Bay , PQQ (Biochemistry) , Bacterial diversity
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4109 , http://hdl.handle.net/10962/d1012943
- Description: Algoa Bay Latrunculid sponges are well known for their production of cytotoxic pyrroloiminoquinones with speculation that these secondary metabolites may have a microbial origin. This study describes a thorough investigation into the bacterial community associated with Tsitsikamma favus, Tsitsikamma scurra a newly described Latrunculia sp. and a yellow encrusting sponge associated with T. scurra. Molecular and chemical characterisation were used in conjunction with traditional taxonomy in identification of the sponge specimens. The 28S rRNA and COX1 analysis confirmed the traditional taxonomy with T. favus and T. scurra being very closely related. Chemical analysis revealed that T. favus and T. scurra shared the discorhabdins 2,4-debromo-3-dihydrodiscorhabdin C, 7,8-dehydro-3-dihydrodiscorhabdin C and 14-bromo-1-hydroxy-discorhabdin V in common with each other and Tsitsikamma pedunculata indicating that these pyrroloiminoquinones are common to Tsitsikamma sponges in general. The bacterial community associated with T. favus was explored using 16S rRNA molecular techniques including DGGE, clonal libraries of full length 16S rRNA genes, as well as 454 pyrosequencing. DGGE analysis revealed that the bacterial community associated with T. favus appeared to be highly conserved, which was confirmed by both the clone library and 454 pyrosequencing, with the Betaproteobacteria as the most dominant class. Further exploration into T. favus, as well as T. scurra, Latrunculia sp. and the yellow encrusting sponge indicated that the bacterial populations associated with each of these sponge species were conserved and species specific. OTU analysis to the species level revealed that T. favus and T. scurra shared an abundant Spirochaete species in common while the most abundant species in the Latrunculia sp. and the yellow encrusting sponge belonged to the class Betaproteobacteria. The exclusivity of the tsitsikammamines to T. favus precipitated attempts to culture the T. favus associated bacteria, with a focus on the dominant betaproteobacterium as indicated by the 16S rRNA clone library. Actinobacteria associated with the Algoa Bay sponge specimens were also cultured and the actinobacterial isolates were sent for screening against Mycobacterium aurum with two Kocuria kristinae isolates and a Streptomyces albdioflavus isolate showing good antimycobacterial activity.
- Full Text:
- Authors: Walmsley, Tara Aisling
- Date: 2014
- Subjects: Sponges -- South Africa -- Algoa Bay , Sponges -- Classification , Metabolites -- South Africa -- Algoa Bay , Marine metabolites -- South Africa -- Algoa Bay , PQQ (Biochemistry) , Bacterial diversity
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4109 , http://hdl.handle.net/10962/d1012943
- Description: Algoa Bay Latrunculid sponges are well known for their production of cytotoxic pyrroloiminoquinones with speculation that these secondary metabolites may have a microbial origin. This study describes a thorough investigation into the bacterial community associated with Tsitsikamma favus, Tsitsikamma scurra a newly described Latrunculia sp. and a yellow encrusting sponge associated with T. scurra. Molecular and chemical characterisation were used in conjunction with traditional taxonomy in identification of the sponge specimens. The 28S rRNA and COX1 analysis confirmed the traditional taxonomy with T. favus and T. scurra being very closely related. Chemical analysis revealed that T. favus and T. scurra shared the discorhabdins 2,4-debromo-3-dihydrodiscorhabdin C, 7,8-dehydro-3-dihydrodiscorhabdin C and 14-bromo-1-hydroxy-discorhabdin V in common with each other and Tsitsikamma pedunculata indicating that these pyrroloiminoquinones are common to Tsitsikamma sponges in general. The bacterial community associated with T. favus was explored using 16S rRNA molecular techniques including DGGE, clonal libraries of full length 16S rRNA genes, as well as 454 pyrosequencing. DGGE analysis revealed that the bacterial community associated with T. favus appeared to be highly conserved, which was confirmed by both the clone library and 454 pyrosequencing, with the Betaproteobacteria as the most dominant class. Further exploration into T. favus, as well as T. scurra, Latrunculia sp. and the yellow encrusting sponge indicated that the bacterial populations associated with each of these sponge species were conserved and species specific. OTU analysis to the species level revealed that T. favus and T. scurra shared an abundant Spirochaete species in common while the most abundant species in the Latrunculia sp. and the yellow encrusting sponge belonged to the class Betaproteobacteria. The exclusivity of the tsitsikammamines to T. favus precipitated attempts to culture the T. favus associated bacteria, with a focus on the dominant betaproteobacterium as indicated by the 16S rRNA clone library. Actinobacteria associated with the Algoa Bay sponge specimens were also cultured and the actinobacterial isolates were sent for screening against Mycobacterium aurum with two Kocuria kristinae isolates and a Streptomyces albdioflavus isolate showing good antimycobacterial activity.
- Full Text:
Curriculum outcomes, teaching practices and learner competencies in isiXhosa in three Grahamstown schools
- Authors: Fobe, Mila Pamella
- Date: 2014
- Subjects: Xhosa language -- Study and teaching (Primary) -- South Africa -- Grahamstown Xhosa language -- Study and teaching (Secondary) -- South Africa -- Grahamstown Language and education -- South Africa -- Grahamstown Curriculum planning Second language acquisition Public schools -- South Africa -- Grahamstown Language policy -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3630 , http://hdl.handle.net/10962/d1012072
- Description: This study looks at the curriculum outcomes, teaching practices and learner competencies in isiXhosa at three Eastern Cape schools and across three different grades, 7-9. It explores the link between language learning and teaching as well as the teaching strategies used within the classroom. In particular, the study seeks to analyse how isiXhosa is taught at three different levels of instruction, namely at Home Language (HL), First Additional Language (FAL) and Second Additional Language (SAL) levels. Qualitative methods were used, and the study took the form of interpretive case studies within the respective schools. The purpose of using multiple case studies was to investigate the reality within the three sites selected. The three schools had three extreme settings, in the sense that one of the schools is a rich isiXhosa environment and the other two schools are English environments. The tools used for data gathering were interviews, classroom observations, and an analysis of documents from the Department of Basic Education. Data was then presented and analysed in Chapter 4 and 5 against the backdrop of an extensive literature review in Chapter 2 as well as a detailed methodological approach as outlined in Chapter 3. One of the findings of this research indicates that in two of the schools the teaching culture is largely from a western perspective, whereas in one of the schools the learners are primarily isiXhosa speaking and teachers use a different linguistic approach to imparting knowledge. In the private and ex-Model C school it was found that a lack of exposure to isiXhosa is the primary cause of language problems for L2 learners. Secondly the L1 is not appropriately maintained or promoted in the school environment because it is presumed that learners are sufficiently exposed to their L1 at home. The research found therefore that in this particular schooling environment there is an inconsistency between the curricula that is taught in relation to the linguistic abilities of the learners, many of whom are mother tongue speakers of isiXhosa. Furthermore and more generally, it was found that teachers are still not well informed concerning South Africa’s Language-in-Education-Policy and there is a need for more inservice training that will focus on the nature of additional language acquisition in order to address the challenges of teaching these languages. The thesis concludes that extensive work needs to be done in order to reposition the teaching of isiXhosa at all three levels, but particularly at FAL level. This research shows that there is a disjuncture between the proposed curriculum/learning outcomes and the standards or levels achieved by the learners, more especially at FAL and SAL where oral proficiency in isiXhosa remains a challenge. Specific recommendations are contained in the final chapter of the thesis which also makes reference to the draft policy of the Ministry of Basic Education regarding the incremental introduction of the teaching of African languages from 2014 onwards. This thesis also makes takes as a point of departure the importance of multilingualism in a multicultural society such as South Africa where language is suggested as a strong factor in the fostering of social cohesion. It is for this reason that the thesis argues that the expert teaching of African languages, in this case isiXhosa, at both mother tongue and second language levels is of fundamental importance to the future of South African society.
- Full Text:
- Authors: Fobe, Mila Pamella
- Date: 2014
- Subjects: Xhosa language -- Study and teaching (Primary) -- South Africa -- Grahamstown Xhosa language -- Study and teaching (Secondary) -- South Africa -- Grahamstown Language and education -- South Africa -- Grahamstown Curriculum planning Second language acquisition Public schools -- South Africa -- Grahamstown Language policy -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3630 , http://hdl.handle.net/10962/d1012072
- Description: This study looks at the curriculum outcomes, teaching practices and learner competencies in isiXhosa at three Eastern Cape schools and across three different grades, 7-9. It explores the link between language learning and teaching as well as the teaching strategies used within the classroom. In particular, the study seeks to analyse how isiXhosa is taught at three different levels of instruction, namely at Home Language (HL), First Additional Language (FAL) and Second Additional Language (SAL) levels. Qualitative methods were used, and the study took the form of interpretive case studies within the respective schools. The purpose of using multiple case studies was to investigate the reality within the three sites selected. The three schools had three extreme settings, in the sense that one of the schools is a rich isiXhosa environment and the other two schools are English environments. The tools used for data gathering were interviews, classroom observations, and an analysis of documents from the Department of Basic Education. Data was then presented and analysed in Chapter 4 and 5 against the backdrop of an extensive literature review in Chapter 2 as well as a detailed methodological approach as outlined in Chapter 3. One of the findings of this research indicates that in two of the schools the teaching culture is largely from a western perspective, whereas in one of the schools the learners are primarily isiXhosa speaking and teachers use a different linguistic approach to imparting knowledge. In the private and ex-Model C school it was found that a lack of exposure to isiXhosa is the primary cause of language problems for L2 learners. Secondly the L1 is not appropriately maintained or promoted in the school environment because it is presumed that learners are sufficiently exposed to their L1 at home. The research found therefore that in this particular schooling environment there is an inconsistency between the curricula that is taught in relation to the linguistic abilities of the learners, many of whom are mother tongue speakers of isiXhosa. Furthermore and more generally, it was found that teachers are still not well informed concerning South Africa’s Language-in-Education-Policy and there is a need for more inservice training that will focus on the nature of additional language acquisition in order to address the challenges of teaching these languages. The thesis concludes that extensive work needs to be done in order to reposition the teaching of isiXhosa at all three levels, but particularly at FAL level. This research shows that there is a disjuncture between the proposed curriculum/learning outcomes and the standards or levels achieved by the learners, more especially at FAL and SAL where oral proficiency in isiXhosa remains a challenge. Specific recommendations are contained in the final chapter of the thesis which also makes reference to the draft policy of the Ministry of Basic Education regarding the incremental introduction of the teaching of African languages from 2014 onwards. This thesis also makes takes as a point of departure the importance of multilingualism in a multicultural society such as South Africa where language is suggested as a strong factor in the fostering of social cohesion. It is for this reason that the thesis argues that the expert teaching of African languages, in this case isiXhosa, at both mother tongue and second language levels is of fundamental importance to the future of South African society.
- Full Text:
Fishing for resilience : herbivore and algal dynamics on coral reefs in Kenya.
- Authors: Humphries, Austin Turner
- Date: 2014
- Subjects: Coral reef conservation -- Kenya , Coral reef ecology -- Kenya , Coral reef biology -- Kenya , Coral reef fishes -- Kenya , Herbivores -- Kenya , Algae -- Control -- Kenya , Fishery management -- Kenya
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5877 , http://hdl.handle.net/10962/d1013147
- Description: Herbivory is a key process that mediates the abundance of primary producers and community composition in both terrestrial and aquatic ecosystems. On tropical coral reefs, changes in herbivory are often related to phase shifts between coral-dominance and dominance by seaweeds, or foliose macroalgae. Resilience or capacity to resist and reverse such phase shifts is, therefore, viewed as a critical function on coral reefs. This thesis used grazer exclusion and assay experiments at six sites within three different fisheries management regimes in Kenya to identify the impacts of herbivores (sea urchins and fishes) on algal dynamics in the context of coral reef resilience. First, I examined the grazing rates necessary to prevent phase shifts by quantifying consumption and algal production. Here, I found that, over a 390-day experiment, at least 50 percent of algal production must be consumed to avoid accumulation of algal biomass. Using video observations, I also showed that scraping parrotfishes remove more algae (per unit of fish biomass) than previously assumed, and that sea urchins, if released from predation, have similar impacts to fishes. Then I focused on algal succession, and found that sea urchins and fishes have different effects that are mediated by their abundances and species composition. Where sea urchins were less abundant and parrotfishes absent (e.g. young fisheries closures), progression of algae from turfs to early and then late successional macroalgae occurred rapidly and within 100 days. I then turned my focus to the removal of already established macroalgae (grown for > 1 yr in the absence of herbivores) and showed that sea urchins and browsing fishes were able to remove significant amounts of macroalgae where either herbivore was abundant. However, using multiple-choice selectivity assays and in situ video recordings, I found that browsing fishes fed very selectively with low overlap in diet among species, leading to low functional redundancy within a high diversity system. Finally, using long-term survey data (from 28 sites) to build a 43-year chronosequence, I showed that it is possible that the effects of herbivory will not be constant across transitions from open fishing to fishery closures through non-linear grazing intensity. Therefore, increases in herbivory within fisheries closures may not be immediate and may allow a window of opportunity for algae to go from turf to unpalatable macroalgae until scraping and browsing fishes fully recover from fishing (~ 20 years). The findings in this thesis are novel and raise concern over the potential implications of the slow recovery of parrotfishes or, given lower than expected functional redundancy in grazing effects, the absence of even one browsing fish species in fisheries closures. Overall, this thesis highlights the importance of herbivore community dynamics in mediating interactions among algae, and provides new insights for conservation and management actions that attempt to bolster the resilience of coral reefs.
- Full Text:
- Authors: Humphries, Austin Turner
- Date: 2014
- Subjects: Coral reef conservation -- Kenya , Coral reef ecology -- Kenya , Coral reef biology -- Kenya , Coral reef fishes -- Kenya , Herbivores -- Kenya , Algae -- Control -- Kenya , Fishery management -- Kenya
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5877 , http://hdl.handle.net/10962/d1013147
- Description: Herbivory is a key process that mediates the abundance of primary producers and community composition in both terrestrial and aquatic ecosystems. On tropical coral reefs, changes in herbivory are often related to phase shifts between coral-dominance and dominance by seaweeds, or foliose macroalgae. Resilience or capacity to resist and reverse such phase shifts is, therefore, viewed as a critical function on coral reefs. This thesis used grazer exclusion and assay experiments at six sites within three different fisheries management regimes in Kenya to identify the impacts of herbivores (sea urchins and fishes) on algal dynamics in the context of coral reef resilience. First, I examined the grazing rates necessary to prevent phase shifts by quantifying consumption and algal production. Here, I found that, over a 390-day experiment, at least 50 percent of algal production must be consumed to avoid accumulation of algal biomass. Using video observations, I also showed that scraping parrotfishes remove more algae (per unit of fish biomass) than previously assumed, and that sea urchins, if released from predation, have similar impacts to fishes. Then I focused on algal succession, and found that sea urchins and fishes have different effects that are mediated by their abundances and species composition. Where sea urchins were less abundant and parrotfishes absent (e.g. young fisheries closures), progression of algae from turfs to early and then late successional macroalgae occurred rapidly and within 100 days. I then turned my focus to the removal of already established macroalgae (grown for > 1 yr in the absence of herbivores) and showed that sea urchins and browsing fishes were able to remove significant amounts of macroalgae where either herbivore was abundant. However, using multiple-choice selectivity assays and in situ video recordings, I found that browsing fishes fed very selectively with low overlap in diet among species, leading to low functional redundancy within a high diversity system. Finally, using long-term survey data (from 28 sites) to build a 43-year chronosequence, I showed that it is possible that the effects of herbivory will not be constant across transitions from open fishing to fishery closures through non-linear grazing intensity. Therefore, increases in herbivory within fisheries closures may not be immediate and may allow a window of opportunity for algae to go from turf to unpalatable macroalgae until scraping and browsing fishes fully recover from fishing (~ 20 years). The findings in this thesis are novel and raise concern over the potential implications of the slow recovery of parrotfishes or, given lower than expected functional redundancy in grazing effects, the absence of even one browsing fish species in fisheries closures. Overall, this thesis highlights the importance of herbivore community dynamics in mediating interactions among algae, and provides new insights for conservation and management actions that attempt to bolster the resilience of coral reefs.
- Full Text:
Good-Gooder-Goodest
- Authors: Majola, Fundile Lawrence
- Date: 2014
- Subjects: South African fiction (English) -- 21st century , Xhosa fiction -- 21st century , Short stories, South African -- 21st century , Short stories, Xhosa -- 21st century , Creative writing (Higher education) -- Research -- South Africa , Creative writing -- Fiction , South African fiction -- Study and teaching (Higher)
- Language: English , Xhosa
- Type: Thesis , Masters , MA
- Identifier: vital:5982 , http://hdl.handle.net/10962/d1015657
- Description: My stories are set in the townships, and move with the vigorous rhythms and jagged structures of township life. Some of them are written in English and others in isiXhosa. Some of the dialogue is township slang, a mixture of languages; and pure isiXhosa. The stories follow no particular pattern and are arranged according to any form of chronology, and different voices, at times as a man/boy and in others as a girl. The characters are not related each story perfectly stands for itself. Some of the stories hark back to the days of apartheid and are seen through the eyes of a child confused by the humiliations of his elders. , Amabali am asekelwe ezilokishini yaye ahambelana neemeko ezimaxongo zokuphila zasezilokishini apho yaye amanye asukela kwixesha lengcinezelo yesizwe esimnyama. Imiba echatshazelwa kula mabali iquka intlupheko, intiyo kwakunye nokuphilisana koluntu ezilokishini, phantsi kwezo meko. Amabali la ndizame ukuwenza alandele indlela yokubalisa yhenkwenkwana enguSkhumba, ethi ibone iqwalasele iimeko zokuphila zabantu bohlanga lwayo. Ingqokelela esisiqendu sokuqala yona ibhalwe ze yangeniswa ngesiNgesi. , This thesis is presented in two parts: English and isiXhosa.
- Full Text:
- Authors: Majola, Fundile Lawrence
- Date: 2014
- Subjects: South African fiction (English) -- 21st century , Xhosa fiction -- 21st century , Short stories, South African -- 21st century , Short stories, Xhosa -- 21st century , Creative writing (Higher education) -- Research -- South Africa , Creative writing -- Fiction , South African fiction -- Study and teaching (Higher)
- Language: English , Xhosa
- Type: Thesis , Masters , MA
- Identifier: vital:5982 , http://hdl.handle.net/10962/d1015657
- Description: My stories are set in the townships, and move with the vigorous rhythms and jagged structures of township life. Some of them are written in English and others in isiXhosa. Some of the dialogue is township slang, a mixture of languages; and pure isiXhosa. The stories follow no particular pattern and are arranged according to any form of chronology, and different voices, at times as a man/boy and in others as a girl. The characters are not related each story perfectly stands for itself. Some of the stories hark back to the days of apartheid and are seen through the eyes of a child confused by the humiliations of his elders. , Amabali am asekelwe ezilokishini yaye ahambelana neemeko ezimaxongo zokuphila zasezilokishini apho yaye amanye asukela kwixesha lengcinezelo yesizwe esimnyama. Imiba echatshazelwa kula mabali iquka intlupheko, intiyo kwakunye nokuphilisana koluntu ezilokishini, phantsi kwezo meko. Amabali la ndizame ukuwenza alandele indlela yokubalisa yhenkwenkwana enguSkhumba, ethi ibone iqwalasele iimeko zokuphila zabantu bohlanga lwayo. Ingqokelela esisiqendu sokuqala yona ibhalwe ze yangeniswa ngesiNgesi. , This thesis is presented in two parts: English and isiXhosa.
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Social learning in community based natural resource management project (CBNRM) : a case study of Chipembere gardening project in Zimbabwe.
- Authors: Mukwambo, Robson
- Date: 2014
- Subjects: Social learning -- Zimbabwe , Social learning -- Case studies , Vegetable gardening -- Zimbabwe , Economic development projects -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2014 , http://hdl.handle.net/10962/d1016363
- Description: This investigation of social learning processes in the Chipembere gardening project was conducted in Rockvale village one in Sebakwe communal area in the Midlands province of Zimbabwe. In essence, the study sought to explore how the Chipembere gardening project as a community-based natural resource management initiative (CBNRM), was reflecting and supporting social learning processes of change. It also sought to enrich and deepen an organizational understanding of social learning and to generate ideas and draw recommendations that could be used to strengthen learning in other CBNRM projects. The research was undertaken as a qualitative case study with data generated through semi-structured interviews with individuals and groups. It also included an analysis of project documents and an extended period of participant observation on site and in the gardening activities. Data were indexed and coded for generating analytical memos that were used to extract and represent the scope of social learning interations within the developing project. The study found that within the Chipembere gardening project a wide range of learning interactions were significant in shaping the developing project. Furthermore, these interactions were earmarked as the major drivers of social learning processes within the project. The study concluded that the social learning interactions amongst the gardeners in the Chipembere community garden were instrumental in fostering change that enhanced community livelinhoods and wellbeing.
- Full Text:
- Authors: Mukwambo, Robson
- Date: 2014
- Subjects: Social learning -- Zimbabwe , Social learning -- Case studies , Vegetable gardening -- Zimbabwe , Economic development projects -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2014 , http://hdl.handle.net/10962/d1016363
- Description: This investigation of social learning processes in the Chipembere gardening project was conducted in Rockvale village one in Sebakwe communal area in the Midlands province of Zimbabwe. In essence, the study sought to explore how the Chipembere gardening project as a community-based natural resource management initiative (CBNRM), was reflecting and supporting social learning processes of change. It also sought to enrich and deepen an organizational understanding of social learning and to generate ideas and draw recommendations that could be used to strengthen learning in other CBNRM projects. The research was undertaken as a qualitative case study with data generated through semi-structured interviews with individuals and groups. It also included an analysis of project documents and an extended period of participant observation on site and in the gardening activities. Data were indexed and coded for generating analytical memos that were used to extract and represent the scope of social learning interations within the developing project. The study found that within the Chipembere gardening project a wide range of learning interactions were significant in shaping the developing project. Furthermore, these interactions were earmarked as the major drivers of social learning processes within the project. The study concluded that the social learning interactions amongst the gardeners in the Chipembere community garden were instrumental in fostering change that enhanced community livelinhoods and wellbeing.
- Full Text:
Petrogenesis of the Bysteek and Koenap Formation Migmatites, Central Namaqualand
- Authors: Moodley, Jason Anthony
- Date: 2013
- Subjects: Petrogenesis -- South Africa -- Namaqualand Migmatite -- South Africa -- Namaqualand Granulite -- South Africa -- Namaqualand Thermodynamics Geology, Stratigraphic -- Proterozoic Geology, Stratigraphic -- Proterozoic -- South Africa -- Namaqualand
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4914 , http://hdl.handle.net/10962/d1001574
- Description: The Mesoproterozoic rocks of the Bysteek and Koenap Formations of the Arribees Group are exposed within a NW-SE striking antiformal structure comprised of mafic granulites and metapelitic diatexites, and a number of marble and calc-silicate rock layers. The mafic granulites of the Bysteek Formation show a typological variety of anatectic features, including nebulitic, stromatitic mesosomes, melanosomes, quartz syenitic leucocratic vein networks and syenitic pools. Melanosomes consist of hedenbergitic to diopside-rich clinopyroxene (XMg: 0.40), anorthitic plagioclase (An90), with some quartz, minor apatite and titanite. Anatexis was caused by biotite dehydration melting and formed a melt of probably granitic composition. The leucosome composition ranges from either alkali-feldspar-granitic to plagioclase rich or granitic. This variation is interpreted as a result of variable extraction of melt from the source to granitic pools. The diatexites of the Koenap Formation are most likely of metapelitic or meta-greywacke origin. They are texturally variable but always contain high modal contents of alkali feldspar and quartz which generally form magmatic textures. Almandine-rich garnet (XMg: 0.18-0.25), cordierite (XMg: 0.71) form secondary biotite, sillimanite and magnetite during retrograde breakdown. Thermodynamic modelling of mafic granulite compositions suggests peak P-T conditions of ~865 °C and 8.6 kbar. Occasionally, garnet rich in ferric iron (XAdr: 0.55) forms by plagioclase-clinopyroxene breakdown under oxidising conditions at ~6 kilobar and ~ 800 °C. At the same stage amphibole forms in some melanosomes. P-T estimations for the diatexites based on thermodynamic modelling suggest the equilibration of the assemblage garnet, cordierite, alkali feldspar and melt at ~860 °C and 5.5 kbar. Conditions comparable to the peak pressure in the mafic granulites could not be established. However, since the diatexites and the mafic granulites are closely related in the field and no evidence of juxtaposition after the thermal peak exists, the P-T record of the diatexites might be incomplete
- Full Text:
- Authors: Moodley, Jason Anthony
- Date: 2013
- Subjects: Petrogenesis -- South Africa -- Namaqualand Migmatite -- South Africa -- Namaqualand Granulite -- South Africa -- Namaqualand Thermodynamics Geology, Stratigraphic -- Proterozoic Geology, Stratigraphic -- Proterozoic -- South Africa -- Namaqualand
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4914 , http://hdl.handle.net/10962/d1001574
- Description: The Mesoproterozoic rocks of the Bysteek and Koenap Formations of the Arribees Group are exposed within a NW-SE striking antiformal structure comprised of mafic granulites and metapelitic diatexites, and a number of marble and calc-silicate rock layers. The mafic granulites of the Bysteek Formation show a typological variety of anatectic features, including nebulitic, stromatitic mesosomes, melanosomes, quartz syenitic leucocratic vein networks and syenitic pools. Melanosomes consist of hedenbergitic to diopside-rich clinopyroxene (XMg: 0.40), anorthitic plagioclase (An90), with some quartz, minor apatite and titanite. Anatexis was caused by biotite dehydration melting and formed a melt of probably granitic composition. The leucosome composition ranges from either alkali-feldspar-granitic to plagioclase rich or granitic. This variation is interpreted as a result of variable extraction of melt from the source to granitic pools. The diatexites of the Koenap Formation are most likely of metapelitic or meta-greywacke origin. They are texturally variable but always contain high modal contents of alkali feldspar and quartz which generally form magmatic textures. Almandine-rich garnet (XMg: 0.18-0.25), cordierite (XMg: 0.71) form secondary biotite, sillimanite and magnetite during retrograde breakdown. Thermodynamic modelling of mafic granulite compositions suggests peak P-T conditions of ~865 °C and 8.6 kbar. Occasionally, garnet rich in ferric iron (XAdr: 0.55) forms by plagioclase-clinopyroxene breakdown under oxidising conditions at ~6 kilobar and ~ 800 °C. At the same stage amphibole forms in some melanosomes. P-T estimations for the diatexites based on thermodynamic modelling suggest the equilibration of the assemblage garnet, cordierite, alkali feldspar and melt at ~860 °C and 5.5 kbar. Conditions comparable to the peak pressure in the mafic granulites could not be established. However, since the diatexites and the mafic granulites are closely related in the field and no evidence of juxtaposition after the thermal peak exists, the P-T record of the diatexites might be incomplete
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The integration of mapwork and environmental issues using local context in FET Geography: an investigation of current pedagogic practices to inform professional development
- Authors: Batyi, Kekeletso Rejoyce
- Date: 2012
- Subjects: Geography -- South Africa -- Grahamstown -- Study and teaching (Secondary) Maps -- Study and teaching (Secondary) -- South Africa -- Grahamstown Environmental education -- Study and teaching (Secondary) -- South Africa -- Grahamstown Teachers -- Training of -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1580 , http://hdl.handle.net/10962/d1003462
- Description: This is an interpretative case study of four Grahamstown Education District Further Education and Training (FET) schools. The study sets out to investigate how Geography teachers integrate mapwork and environmental issues using local context, with the intention of providing insights for future professional development. Data for this study were generated using qualitative methods such as document analysis, semi-structured interviews and lesson observations. Interviews were conducted with geography teachers, the subject advisor and a workshop facilitator. The evidence generated in the study revealed that contrary to the integrative design of the curriculum, there is a superficial integration of mapwork and environmental issues as well as a cursory reference to and use of local context. This was noted in both professional development support workshops and classroom practice. The study finds that efforts to improve performance in geography need to pay closer attention to curriculum policy that calls for an integration and localization of knowledge and skills for coherence and relevance. It also notes that there is a need for a focus on real-world problem solving in social, economic, cultural and physical environments through the use of inquiry-based local fieldwork. Local investigations provide an integrative space for content and skills as well as being an important point of reference from which learners can compare and contrast issues in other places such as provincial, national, continental, and global locations. A professional development programme that emphasizes integration and contextualization alongside the current focus on basic skills training is proposed to improve what teachers are delivering in the classroom and to support enquiry-based fieldwork and research to strengthen a place-based relevance in local, national and international contexts. Finally an exemplar for professional development is briefly developed for the topic of soil erosion.
- Full Text:
- Authors: Batyi, Kekeletso Rejoyce
- Date: 2012
- Subjects: Geography -- South Africa -- Grahamstown -- Study and teaching (Secondary) Maps -- Study and teaching (Secondary) -- South Africa -- Grahamstown Environmental education -- Study and teaching (Secondary) -- South Africa -- Grahamstown Teachers -- Training of -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1580 , http://hdl.handle.net/10962/d1003462
- Description: This is an interpretative case study of four Grahamstown Education District Further Education and Training (FET) schools. The study sets out to investigate how Geography teachers integrate mapwork and environmental issues using local context, with the intention of providing insights for future professional development. Data for this study were generated using qualitative methods such as document analysis, semi-structured interviews and lesson observations. Interviews were conducted with geography teachers, the subject advisor and a workshop facilitator. The evidence generated in the study revealed that contrary to the integrative design of the curriculum, there is a superficial integration of mapwork and environmental issues as well as a cursory reference to and use of local context. This was noted in both professional development support workshops and classroom practice. The study finds that efforts to improve performance in geography need to pay closer attention to curriculum policy that calls for an integration and localization of knowledge and skills for coherence and relevance. It also notes that there is a need for a focus on real-world problem solving in social, economic, cultural and physical environments through the use of inquiry-based local fieldwork. Local investigations provide an integrative space for content and skills as well as being an important point of reference from which learners can compare and contrast issues in other places such as provincial, national, continental, and global locations. A professional development programme that emphasizes integration and contextualization alongside the current focus on basic skills training is proposed to improve what teachers are delivering in the classroom and to support enquiry-based fieldwork and research to strengthen a place-based relevance in local, national and international contexts. Finally an exemplar for professional development is briefly developed for the topic of soil erosion.
- Full Text:
The role of teacher cognition in the integration of technology into English teaching: a case study
- Authors: Baron, Elizabeth Mary
- Date: 2011
- Subjects: English teachers -- Effect of technological innovations on English teachers -- Psychology English teachers -- Attitudes Language and languages -- Study and teaching -- Computer-assisted instruction Educational technology Computer-assisted instruction
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1753 , http://hdl.handle.net/10962/d1003637
- Description: Technology, in one or more of its various forms, is now a part of everyday life for most South African citizens. Many schools are equipped with various forms of technology, at great cost to sponsors, schools, parents or the government. However, this technology is not always exploited and full use is not made of it. As access is not the issue, other factors needed to be considered: in this case, teachers’ beliefs, attitudes and knowledge. This thesis explores the cognitive factors which affect the acceptance and use of technology. Teacher cognition and the factors which influence teacher cognition were examined. Following Borg, teacher cognition is defined as “the unobservable cognitive dimension of teaching – what teachers know, believe and think” (Borg, 2003, p. 81). Teacher cognition determines whether or not a teacher will use technology, if the external barrier of access is removed. In order to study the various aspect of teacher cognition, a case study was performed, which studied 6 teachers at 4 schools. All the schools in this study had some level of access to technology. Following Borg, initial experiences with the educational system (i.e. the teacher’s experience as a learner), teacher training, the context the teacher worked in (as well as social factors and private use) and classroom experience were all examined in order to discover the factors which most affect technology acceptance in teaching. The findings show that having easy access to well-maintained and functioning technology cannot be underestimated. In the study, support from other teachers, particularly those in leadership roles, led to an increase in technology use. This support needed to be explicit; general support did not seem to be effective. These findings suggest that technology integration needs to happen at a ‘whole school’ level.
- Full Text:
- Authors: Baron, Elizabeth Mary
- Date: 2011
- Subjects: English teachers -- Effect of technological innovations on English teachers -- Psychology English teachers -- Attitudes Language and languages -- Study and teaching -- Computer-assisted instruction Educational technology Computer-assisted instruction
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1753 , http://hdl.handle.net/10962/d1003637
- Description: Technology, in one or more of its various forms, is now a part of everyday life for most South African citizens. Many schools are equipped with various forms of technology, at great cost to sponsors, schools, parents or the government. However, this technology is not always exploited and full use is not made of it. As access is not the issue, other factors needed to be considered: in this case, teachers’ beliefs, attitudes and knowledge. This thesis explores the cognitive factors which affect the acceptance and use of technology. Teacher cognition and the factors which influence teacher cognition were examined. Following Borg, teacher cognition is defined as “the unobservable cognitive dimension of teaching – what teachers know, believe and think” (Borg, 2003, p. 81). Teacher cognition determines whether or not a teacher will use technology, if the external barrier of access is removed. In order to study the various aspect of teacher cognition, a case study was performed, which studied 6 teachers at 4 schools. All the schools in this study had some level of access to technology. Following Borg, initial experiences with the educational system (i.e. the teacher’s experience as a learner), teacher training, the context the teacher worked in (as well as social factors and private use) and classroom experience were all examined in order to discover the factors which most affect technology acceptance in teaching. The findings show that having easy access to well-maintained and functioning technology cannot be underestimated. In the study, support from other teachers, particularly those in leadership roles, led to an increase in technology use. This support needed to be explicit; general support did not seem to be effective. These findings suggest that technology integration needs to happen at a ‘whole school’ level.
- Full Text:
Protein secondary structure prediction using neural networks and support vector machines
- Authors: Tsilo, Lipontseng Cecilia
- Date: 2009
- Subjects: Neural networks (Computer science) , Support vector machines , Proteins -- Structure -- Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5569 , http://hdl.handle.net/10962/d1002809 , Neural networks (Computer science) , Support vector machines , Proteins -- Structure -- Mathematical models
- Description: Predicting the secondary structure of proteins is important in biochemistry because the 3D structure can be determined from the local folds that are found in secondary structures. Moreover, knowing the tertiary structure of proteins can assist in determining their functions. The objective of this thesis is to compare the performance of Neural Networks (NN) and Support Vector Machines (SVM) in predicting the secondary structure of 62 globular proteins from their primary sequence. For each NN and SVM, we created six binary classifiers to distinguish between the classes’ helices (H) strand (E), and coil (C). For NN we use Resilient Backpropagation training with and without early stopping. We use NN with either no hidden layer or with one hidden layer with 1,2,...,40 hidden neurons. For SVM we use a Gaussian kernel with parameter fixed at = 0.1 and varying cost parameters C in the range [0.1,5]. 10- fold cross-validation is used to obtain overall estimates for the probability of making a correct prediction. Our experiments indicate for NN and SVM that the different binary classifiers have varying accuracies: from 69% correct predictions for coils vs. non-coil up to 80% correct predictions for stand vs. non-strand. It is further demonstrated that NN with no hidden layer or not more than 2 hidden neurons in the hidden layer are sufficient for better predictions. For SVM we show that the estimated accuracies do not depend on the value of the cost parameter. As a major result, we will demonstrate that the accuracy estimates of NN and SVM binary classifiers cannot distinguish. This contradicts a modern belief in bioinformatics that SVM outperforms other predictors.
- Full Text:
- Authors: Tsilo, Lipontseng Cecilia
- Date: 2009
- Subjects: Neural networks (Computer science) , Support vector machines , Proteins -- Structure -- Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5569 , http://hdl.handle.net/10962/d1002809 , Neural networks (Computer science) , Support vector machines , Proteins -- Structure -- Mathematical models
- Description: Predicting the secondary structure of proteins is important in biochemistry because the 3D structure can be determined from the local folds that are found in secondary structures. Moreover, knowing the tertiary structure of proteins can assist in determining their functions. The objective of this thesis is to compare the performance of Neural Networks (NN) and Support Vector Machines (SVM) in predicting the secondary structure of 62 globular proteins from their primary sequence. For each NN and SVM, we created six binary classifiers to distinguish between the classes’ helices (H) strand (E), and coil (C). For NN we use Resilient Backpropagation training with and without early stopping. We use NN with either no hidden layer or with one hidden layer with 1,2,...,40 hidden neurons. For SVM we use a Gaussian kernel with parameter fixed at = 0.1 and varying cost parameters C in the range [0.1,5]. 10- fold cross-validation is used to obtain overall estimates for the probability of making a correct prediction. Our experiments indicate for NN and SVM that the different binary classifiers have varying accuracies: from 69% correct predictions for coils vs. non-coil up to 80% correct predictions for stand vs. non-strand. It is further demonstrated that NN with no hidden layer or not more than 2 hidden neurons in the hidden layer are sufficient for better predictions. For SVM we show that the estimated accuracies do not depend on the value of the cost parameter. As a major result, we will demonstrate that the accuracy estimates of NN and SVM binary classifiers cannot distinguish. This contradicts a modern belief in bioinformatics that SVM outperforms other predictors.
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The possibility of psychotherapeutic privilege in South Africa
- Authors: Gewald, Rieka Susan
- Date: 2009
- Subjects: Psychology -- Moral and ethical aspects -- South Africa Psychologists -- Professional ethics -- South Africa Psychotherapists -- Professional ethics -- South Africa Confidential communications -- South Africa Privileges and immunities -- South Africa Evidence (Law) -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3717 , http://hdl.handle.net/10962/d1008208
- Description: Privilege is an evidential principle which, on the grounds of public policy, excludes evidence relevant and otherwise admissible. This thesis aims to discover whether privilege should be applied to the psychotherapeutic profession in South Africa. At present, the only profession in South Africa afforded privilege is the legal profession. There are two main theoretical justifications for privilege: the utilitarian and the individual/human rights approach. This thesis considers whether the psychotherapeutic profession warrants privilege under either theory, and recommends that the law of privilege integrate both theories rather than adopt one or the other. The impact of the Constitution and the right to privacy receive particular attention. Very little literature or case law on the question of psychotherapeutic privilege was found in South Africa. Consequently, extensive comparative research into the common-law systems of England, Canada and United States of America was done. This research yielded some interesting findings. The first is that case-by-case development of the law of privilege is uncel1ain and fragmented. The next is that psychotherapeutic privilege exists in almost absolute form in the United States of America, but is littered with lacunae causing as much uncertainty as the case-by-case approach to privilege law. The most helpful method of dealing with the problem was found in Canada, where a two-stage approach to protecting personal information, including psychotherapeutic records, has been developed. In light of this research, this thesis reassesses the original viability of psychotherapeutic privilege in South Africa. Privilege, it was found, is not the best solution to protecting psychotherapeutic communications. This thesis recommends legislative adoption of an amended two-stage approach based on the Canadian model for sexual offence trials as the best method of protecting psychotherapeutic communications in both civil and criminal proceedings. The thesis ends by suggesting draft legislative provisions.
- Full Text:
- Authors: Gewald, Rieka Susan
- Date: 2009
- Subjects: Psychology -- Moral and ethical aspects -- South Africa Psychologists -- Professional ethics -- South Africa Psychotherapists -- Professional ethics -- South Africa Confidential communications -- South Africa Privileges and immunities -- South Africa Evidence (Law) -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3717 , http://hdl.handle.net/10962/d1008208
- Description: Privilege is an evidential principle which, on the grounds of public policy, excludes evidence relevant and otherwise admissible. This thesis aims to discover whether privilege should be applied to the psychotherapeutic profession in South Africa. At present, the only profession in South Africa afforded privilege is the legal profession. There are two main theoretical justifications for privilege: the utilitarian and the individual/human rights approach. This thesis considers whether the psychotherapeutic profession warrants privilege under either theory, and recommends that the law of privilege integrate both theories rather than adopt one or the other. The impact of the Constitution and the right to privacy receive particular attention. Very little literature or case law on the question of psychotherapeutic privilege was found in South Africa. Consequently, extensive comparative research into the common-law systems of England, Canada and United States of America was done. This research yielded some interesting findings. The first is that case-by-case development of the law of privilege is uncel1ain and fragmented. The next is that psychotherapeutic privilege exists in almost absolute form in the United States of America, but is littered with lacunae causing as much uncertainty as the case-by-case approach to privilege law. The most helpful method of dealing with the problem was found in Canada, where a two-stage approach to protecting personal information, including psychotherapeutic records, has been developed. In light of this research, this thesis reassesses the original viability of psychotherapeutic privilege in South Africa. Privilege, it was found, is not the best solution to protecting psychotherapeutic communications. This thesis recommends legislative adoption of an amended two-stage approach based on the Canadian model for sexual offence trials as the best method of protecting psychotherapeutic communications in both civil and criminal proceedings. The thesis ends by suggesting draft legislative provisions.
- Full Text:
The importance of managing cultural change in the succession process within family businesses in the Gauteng area
- Authors: Hynd, Dale Vaughan
- Date: 2003
- Subjects: Family-owned business enterprises -- South Africa Family-owned business enterprises -- Succession Corporate culture -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3173 , http://hdl.handle.net/10962/d1007802
- Description: The aim of this research was to ascertain the implications and the impact that the succession process would have on the organisational culture of family businesses. In an attempt to answer this, the researcher asked three questions surrounding the succession process and its relationship with organisational culture. The questions related to the extent to which the family business was prepared for change in management; what changes occurred before, during, and immediately after the succession process, and what results these changes had on the organisational culture. Family businesses account for a large proportion of the national and global market activities, and so it is imperative that attention be paid to any problems they may experience. As it is, family businesses have difficulty in successions, with roughly one third of first generation family businesses surviving the succession process. It is the aim of this research to explore the contribution organisational culture has in the large failure rate of succession with family businesses. When successors enter into the organisation, they bring with them different perspectives on managerial issues suggesting that a change in leadership style will occur as a result of a succession. In answering the research questions, the researcher embarked on a two-phase research methodology utilising a quantitative and qualitative process. This triangulation process incorporates a self-administrated survey questionnaire, and six in-depth interviews. The survey questionnaire and interview schedules were structured using a combination of elements obtained from Harris's (1998) and Levinson's (1972). The survey data was analysed using various statistical methods, predominantly a Factor Analysis, where as Abstract iii the interviews were analysed using a theme retrieval process. The two processes were combined to yield the results. The findings of the research conclude that through the introduction of the successor in the change process, a new leadership style is introduced into the business. The new leader changes policies, practices and procedures, which are related to organisational climate and are the tangible aspects of organisational culture. Altering the climate essentially alters the culture, which may result in anxiety within the organisation and lead to tension. If these issues are not addressed, they may result in the demise of family businesses.
- Full Text:
- Authors: Hynd, Dale Vaughan
- Date: 2003
- Subjects: Family-owned business enterprises -- South Africa Family-owned business enterprises -- Succession Corporate culture -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3173 , http://hdl.handle.net/10962/d1007802
- Description: The aim of this research was to ascertain the implications and the impact that the succession process would have on the organisational culture of family businesses. In an attempt to answer this, the researcher asked three questions surrounding the succession process and its relationship with organisational culture. The questions related to the extent to which the family business was prepared for change in management; what changes occurred before, during, and immediately after the succession process, and what results these changes had on the organisational culture. Family businesses account for a large proportion of the national and global market activities, and so it is imperative that attention be paid to any problems they may experience. As it is, family businesses have difficulty in successions, with roughly one third of first generation family businesses surviving the succession process. It is the aim of this research to explore the contribution organisational culture has in the large failure rate of succession with family businesses. When successors enter into the organisation, they bring with them different perspectives on managerial issues suggesting that a change in leadership style will occur as a result of a succession. In answering the research questions, the researcher embarked on a two-phase research methodology utilising a quantitative and qualitative process. This triangulation process incorporates a self-administrated survey questionnaire, and six in-depth interviews. The survey questionnaire and interview schedules were structured using a combination of elements obtained from Harris's (1998) and Levinson's (1972). The survey data was analysed using various statistical methods, predominantly a Factor Analysis, where as Abstract iii the interviews were analysed using a theme retrieval process. The two processes were combined to yield the results. The findings of the research conclude that through the introduction of the successor in the change process, a new leadership style is introduced into the business. The new leader changes policies, practices and procedures, which are related to organisational climate and are the tangible aspects of organisational culture. Altering the climate essentially alters the culture, which may result in anxiety within the organisation and lead to tension. If these issues are not addressed, they may result in the demise of family businesses.
- Full Text:
The development from a Wesleyan perspective of an appropriate model of multi-cultural ministry, from within a traditionally mono-cultural Methodist congregation
- Authors: Rist, Timothy John
- Date: 1999
- Subjects: Wesley, John, 1703-1791 , Religion and culture , Methodist church buildings -- South Africa , Methodist church buildings -- South Africa -- Bloemfontein
- Language: English
- Type: Thesis , Masters , MTh
- Identifier: vital:1309 , http://hdl.handle.net/10962/d1018218
- Description: From introduction: The intention of this thesis is to develop a model for multi-cultural ministry, and, in so doing, to enable Trinity Methodist Church, Charles Street, Bloemfontein to provide a comprehensive and meaningful ministry to all people, one that is not limited by the constraints of language and culture but which transcends them. The fact that Trinity is a Methodist Church means that I will be establishing the "Model for Multi-Cultural Ministry" firmly within Wesleyan theology. South Africa has undergone far-reaching political change since the general elections of April 1994. This political transformation has emphasised a need for the bringing together of people across the barriers of race, culture and religion. In this thesis I will be focusing my attention on the latter - the realm of religion - and specifically that of Christianity. Furthermore, I will be restricting my attention to a specific congregation within the denomination of Methodism, within the religion of Christianity, namely Trinity Methodist Church, Charles Street, Bloemfontein'. The "Model for MultiCultural Ministry" developed in this thesis will therefore be 'congregation specific'. The Methodist ChurcQ of Southern Africa2 proclaims itself to be a Church "one and undivided" (Minutes: 1980: 65: para l(a) ), where people from all racial groups can worship God together in a meaningful way. In many respects this is not the case. The years of political pressure that the (MCSA) has endured, in particular the years of legislated Apartheid (1948-1989), ensured that existing divisions between the Methodist congregations became entrenched along racial, cultural and religious lines (Thompson: 1990: 187ff). The Group Areas Act (1950) is but one such example where the National Party Government "divided urban areas into zones where members of one specified race alone could live and work" (Thompson: 1990: 194). The homeland policy (implemented from 1963, but legislated from 1971 in the Bantu Homelands Constitution Act).
- Full Text:
- Authors: Rist, Timothy John
- Date: 1999
- Subjects: Wesley, John, 1703-1791 , Religion and culture , Methodist church buildings -- South Africa , Methodist church buildings -- South Africa -- Bloemfontein
- Language: English
- Type: Thesis , Masters , MTh
- Identifier: vital:1309 , http://hdl.handle.net/10962/d1018218
- Description: From introduction: The intention of this thesis is to develop a model for multi-cultural ministry, and, in so doing, to enable Trinity Methodist Church, Charles Street, Bloemfontein to provide a comprehensive and meaningful ministry to all people, one that is not limited by the constraints of language and culture but which transcends them. The fact that Trinity is a Methodist Church means that I will be establishing the "Model for Multi-Cultural Ministry" firmly within Wesleyan theology. South Africa has undergone far-reaching political change since the general elections of April 1994. This political transformation has emphasised a need for the bringing together of people across the barriers of race, culture and religion. In this thesis I will be focusing my attention on the latter - the realm of religion - and specifically that of Christianity. Furthermore, I will be restricting my attention to a specific congregation within the denomination of Methodism, within the religion of Christianity, namely Trinity Methodist Church, Charles Street, Bloemfontein'. The "Model for MultiCultural Ministry" developed in this thesis will therefore be 'congregation specific'. The Methodist ChurcQ of Southern Africa2 proclaims itself to be a Church "one and undivided" (Minutes: 1980: 65: para l(a) ), where people from all racial groups can worship God together in a meaningful way. In many respects this is not the case. The years of political pressure that the (MCSA) has endured, in particular the years of legislated Apartheid (1948-1989), ensured that existing divisions between the Methodist congregations became entrenched along racial, cultural and religious lines (Thompson: 1990: 187ff). The Group Areas Act (1950) is but one such example where the National Party Government "divided urban areas into zones where members of one specified race alone could live and work" (Thompson: 1990: 194). The homeland policy (implemented from 1963, but legislated from 1971 in the Bantu Homelands Constitution Act).
- Full Text:
Biology, stock assessment and management of the panga Pterogymnus laniarius on the Agulhas Bank, South Africa
- Authors: Booth, Anthony John
- Date: 1998
- Subjects: Fish stock assessment -- South Africa Bycatches (Fisheries) -- South Africa Pterogymnus laniarius Fishery management -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5242 , http://hdl.handle.net/10962/d1005085
- Description: The panga, Pterogymnus laniarius (Cuvier, 1830), is a South African endemic sparid fish species. On the Agulhas Bank, South Africa it is a commercially important species, caught as bycatch in the hake directed trawlfisheries and targeted by offshore hook-and-linefishers. Recently there has been considerable interest shown in directing further fishing effort on this species. The lack of a suitable management procedure for teleost bycatch in South Africa was the principal reason for undertaking this study. This thesis investigates aspects the panga's life history, particularly those aspects that have management implications. A full knowledge of this species' distribution and abundance was necessary as this could highlight the existence of any nursery areas, ontogenetic migratory patterns and areas of high spawner biomass. The derived parameter estimates were then included as inputs into stock assessment models to determine the status and productivity of the resource. Growth studies based on sectioned sagittal otoliths revealed that the panga was a relatively slow growing fish with ages of 16 years being recorded. Growth was best described by the von Bertalanffy growth model as Lt=379.4(1-e⁻°·¹³⁽t ⁺ ¹·⁷⁸⁾). Total, natural and fishing mortalities were estimated at 0.36 year⁻¹, 0.28 year⁻¹ and 0.08 year ⁻¹, respectively. Detailed histological examination of the gonads revealed that panga is a late gonochorist, males and females maturing after a non-functional intersexual stage. Females mature at approximately 200 mm fork length or 4 years of age. Reproduction occurs throughout the year although there is a slight peak in winter. Gametogenesis was found to be similar to that of other sparid fishes and marine teleosts in general. The panga feeds predominantly on crustaceans with a distinct ontogenetic shift in feeding habits. Juvenile fish feed predominantly in the water column on mysids after which they move to the benthos. Subadult fish feed principally on ophiuroids and amphipods. Adult fish remain on or near the benthos, feeding predominantly on crabs, and on polychaetes, ophiuroids and fishes to a lesser extent. Several aspects of the panga's biology contribute to its ability to sustain a higher fishing pressure than other sympatric sparid species. These include its late gonochoristic reproductive style, protracted spawning season, maturation before recruitment and preference for soft substratum prey that enables it to utilise large areas of the Agulhas Bank. The panga's longevity, slow growth and low natural mortality rate, however, mitigated against these factors and were considered in the stock assessments. A heterogeneous Geographical Information System (GIS) was developed to analyse the distribution and abundance patterns of the panga. The GIS developed in this thesis makes a significant contribution towards the development of a South African Fisheries Information System to analyse and manage fish resources in general and bycatch resources in particular. The GIS developed in this study combines statistical Generalized Additive Modelling and standard GIS methods. Analysis of fourteen biannual fishery independent biomass surveys, disaggregated by life history stage, revealed that a nursery area for immature fish (<23 cm TL or < 4 years of age) exists on the Central Agulhas Bank. After sexual maturation, approximately 40% of the biomass migrated eastwards, colonising large areas of the Eastern Agulhas Bank.ilie location of the nursery area appears to be a result of the pelagic eggs and larvae being advected towards the coast in an anti-cyclonic gyre, stemming off the Agulhas current and later deposited over the Central Agulhas Bank. The weak bottom currents on the Central Agulhas Bank prevented juvenile loss to the Benguela system. The eurytopy of adult fish to various physical variables such as temperature, dissolved oxygen and stronger currents enabled it to reduce conspecific competition and migrate eastwards with distribution primarily determined by depth. Relative biomass estimates revealed a gradual increase in biomass of 5.5% per annum between 1988 and 1995. Predictions from yield-per-recruit, biomass-per-recruit and spawner biomass-per-recruit analyses showed that there was scope for further exploitation. A FSB₅₀ fishing strategy was considered to be the most appropriate fishing strategy as it did not reduce the spawner biomass-per-recruit to less than 50% of unexploited levels. Effort control was considered the most effective management tool as the age-at-50%-selectivity occurred after age-at-sexual maturity and releasing undersized fish was undesirable due to heavy mortalities resulting from severe barotrauma. The panga resource was also assessed using an age-structured production model. The values for the free parameters of the model were estimated using biomass indices derived from fishery-independent trawl surveys. Although the data were fairly uninformative about the productivity of the resource, the results indicated robustly, that the population has recovered from low levels in the mid-1970's and could sustain higher levels of fishing intensity. Risk analysis calculations were used to assess the sustainability of different catch scenarios. The level of sustainable catch was found to be sensitive to the selectivity pattern of the gear utilised. Both stock assessment methods used in this study to investigate the status of the panga resource showed that the resource could theoretically sustain higher catches. It was found that although the stock could be harvested using available fishing methods, the sympatry of this species with other commercial species was of concern as the latter would form a significant bycatch in a panga directed fishery. The failure of current harvesting methods to address the bycatch problem highlights the management problem in South Africa and stresses the need for creativity by both scientists and fishers in designing new and improved methods for selectively harvesting bycatch fish resources. Considering that no suitable method is currently available to fish the panga stock in a directed fishery the fishery should be managed as status quo until some suitable and efficient gear is developed.
- Full Text:
- Authors: Booth, Anthony John
- Date: 1998
- Subjects: Fish stock assessment -- South Africa Bycatches (Fisheries) -- South Africa Pterogymnus laniarius Fishery management -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5242 , http://hdl.handle.net/10962/d1005085
- Description: The panga, Pterogymnus laniarius (Cuvier, 1830), is a South African endemic sparid fish species. On the Agulhas Bank, South Africa it is a commercially important species, caught as bycatch in the hake directed trawlfisheries and targeted by offshore hook-and-linefishers. Recently there has been considerable interest shown in directing further fishing effort on this species. The lack of a suitable management procedure for teleost bycatch in South Africa was the principal reason for undertaking this study. This thesis investigates aspects the panga's life history, particularly those aspects that have management implications. A full knowledge of this species' distribution and abundance was necessary as this could highlight the existence of any nursery areas, ontogenetic migratory patterns and areas of high spawner biomass. The derived parameter estimates were then included as inputs into stock assessment models to determine the status and productivity of the resource. Growth studies based on sectioned sagittal otoliths revealed that the panga was a relatively slow growing fish with ages of 16 years being recorded. Growth was best described by the von Bertalanffy growth model as Lt=379.4(1-e⁻°·¹³⁽t ⁺ ¹·⁷⁸⁾). Total, natural and fishing mortalities were estimated at 0.36 year⁻¹, 0.28 year⁻¹ and 0.08 year ⁻¹, respectively. Detailed histological examination of the gonads revealed that panga is a late gonochorist, males and females maturing after a non-functional intersexual stage. Females mature at approximately 200 mm fork length or 4 years of age. Reproduction occurs throughout the year although there is a slight peak in winter. Gametogenesis was found to be similar to that of other sparid fishes and marine teleosts in general. The panga feeds predominantly on crustaceans with a distinct ontogenetic shift in feeding habits. Juvenile fish feed predominantly in the water column on mysids after which they move to the benthos. Subadult fish feed principally on ophiuroids and amphipods. Adult fish remain on or near the benthos, feeding predominantly on crabs, and on polychaetes, ophiuroids and fishes to a lesser extent. Several aspects of the panga's biology contribute to its ability to sustain a higher fishing pressure than other sympatric sparid species. These include its late gonochoristic reproductive style, protracted spawning season, maturation before recruitment and preference for soft substratum prey that enables it to utilise large areas of the Agulhas Bank. The panga's longevity, slow growth and low natural mortality rate, however, mitigated against these factors and were considered in the stock assessments. A heterogeneous Geographical Information System (GIS) was developed to analyse the distribution and abundance patterns of the panga. The GIS developed in this thesis makes a significant contribution towards the development of a South African Fisheries Information System to analyse and manage fish resources in general and bycatch resources in particular. The GIS developed in this study combines statistical Generalized Additive Modelling and standard GIS methods. Analysis of fourteen biannual fishery independent biomass surveys, disaggregated by life history stage, revealed that a nursery area for immature fish (<23 cm TL or < 4 years of age) exists on the Central Agulhas Bank. After sexual maturation, approximately 40% of the biomass migrated eastwards, colonising large areas of the Eastern Agulhas Bank.ilie location of the nursery area appears to be a result of the pelagic eggs and larvae being advected towards the coast in an anti-cyclonic gyre, stemming off the Agulhas current and later deposited over the Central Agulhas Bank. The weak bottom currents on the Central Agulhas Bank prevented juvenile loss to the Benguela system. The eurytopy of adult fish to various physical variables such as temperature, dissolved oxygen and stronger currents enabled it to reduce conspecific competition and migrate eastwards with distribution primarily determined by depth. Relative biomass estimates revealed a gradual increase in biomass of 5.5% per annum between 1988 and 1995. Predictions from yield-per-recruit, biomass-per-recruit and spawner biomass-per-recruit analyses showed that there was scope for further exploitation. A FSB₅₀ fishing strategy was considered to be the most appropriate fishing strategy as it did not reduce the spawner biomass-per-recruit to less than 50% of unexploited levels. Effort control was considered the most effective management tool as the age-at-50%-selectivity occurred after age-at-sexual maturity and releasing undersized fish was undesirable due to heavy mortalities resulting from severe barotrauma. The panga resource was also assessed using an age-structured production model. The values for the free parameters of the model were estimated using biomass indices derived from fishery-independent trawl surveys. Although the data were fairly uninformative about the productivity of the resource, the results indicated robustly, that the population has recovered from low levels in the mid-1970's and could sustain higher levels of fishing intensity. Risk analysis calculations were used to assess the sustainability of different catch scenarios. The level of sustainable catch was found to be sensitive to the selectivity pattern of the gear utilised. Both stock assessment methods used in this study to investigate the status of the panga resource showed that the resource could theoretically sustain higher catches. It was found that although the stock could be harvested using available fishing methods, the sympatry of this species with other commercial species was of concern as the latter would form a significant bycatch in a panga directed fishery. The failure of current harvesting methods to address the bycatch problem highlights the management problem in South Africa and stresses the need for creativity by both scientists and fishers in designing new and improved methods for selectively harvesting bycatch fish resources. Considering that no suitable method is currently available to fish the panga stock in a directed fishery the fishery should be managed as status quo until some suitable and efficient gear is developed.
- Full Text:
Guidelines for assessing single borehole yields in secondary aquifers
- Authors: Murray, Eric Charles
- Date: 1997
- Subjects: Aquifers -- Measurement
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:6026 , http://hdl.handle.net/10962/d1005512
- Description: The motivation for this research project arose from the realisation that many South African rural water supply schemes fail due to the over abstraction of groundwater from single boreholes. The main reason for this mis-management of groundwater is a result of inappropriate borehole yield recommendation methods. This research project set out to review existing borehole yield assessment methods and establish new methods which take the shortcomings of existing methods into account. The study is concerned with borehole yield assessment methods applicable to secondary aquifers, since these aquifers are by far the most common in South Africa. The yield assessment methods have been grouped into those that are based on aquifer yield analyses, and on the analysis of single borehole test pump data. In order to assess which methods give suitable yield recommendations, it was necessary to compare the yields obtained using the various methods, with established yields from production boreholes. The focus of the aquifer yield component of the study, was to develop a method for estimating the proportion of recharge that can be abstracted from a single borehole located in a relatively small aquifer. The method was developed by computer simulations of aquifers with different hydraulic properties, and by establishing a formula which describes the relationship between recharge and the abstractable proportion of recharge. Under specific hydrogeological conditions, the recharge based method proved to be reliable in relation to established yields from production boreholes. Of the borehole yield assessment methods based on the analysis of test pump data, none of the existing methods proved to be reliable. However, the yields obtained using the two newly developed methods compared favourably to the established yield of existing production boreholes. Both of these methods are based on the application of the Cooper-Jacob approximation of the Theis equation. This study reviews existing methods and presents newly developed methods for recommending borehole abstraction rates in secondary aquifers. While existing borehole yield assessment methods were found to be unreliable, some of the newly developed methods, if correctly applied, give acceptable yield recommendations.
- Full Text:
- Authors: Murray, Eric Charles
- Date: 1997
- Subjects: Aquifers -- Measurement
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:6026 , http://hdl.handle.net/10962/d1005512
- Description: The motivation for this research project arose from the realisation that many South African rural water supply schemes fail due to the over abstraction of groundwater from single boreholes. The main reason for this mis-management of groundwater is a result of inappropriate borehole yield recommendation methods. This research project set out to review existing borehole yield assessment methods and establish new methods which take the shortcomings of existing methods into account. The study is concerned with borehole yield assessment methods applicable to secondary aquifers, since these aquifers are by far the most common in South Africa. The yield assessment methods have been grouped into those that are based on aquifer yield analyses, and on the analysis of single borehole test pump data. In order to assess which methods give suitable yield recommendations, it was necessary to compare the yields obtained using the various methods, with established yields from production boreholes. The focus of the aquifer yield component of the study, was to develop a method for estimating the proportion of recharge that can be abstracted from a single borehole located in a relatively small aquifer. The method was developed by computer simulations of aquifers with different hydraulic properties, and by establishing a formula which describes the relationship between recharge and the abstractable proportion of recharge. Under specific hydrogeological conditions, the recharge based method proved to be reliable in relation to established yields from production boreholes. Of the borehole yield assessment methods based on the analysis of test pump data, none of the existing methods proved to be reliable. However, the yields obtained using the two newly developed methods compared favourably to the established yield of existing production boreholes. Both of these methods are based on the application of the Cooper-Jacob approximation of the Theis equation. This study reviews existing methods and presents newly developed methods for recommending borehole abstraction rates in secondary aquifers. While existing borehole yield assessment methods were found to be unreliable, some of the newly developed methods, if correctly applied, give acceptable yield recommendations.
- Full Text:
Aspects of the symplectic and metric geometry of classical and quantum physics
- Authors: Russell, Neil Eric
- Date: 1993
- Subjects: Symplectic manifolds Geometry, Differential Geometric quantization Quantum theory Clifford algebras
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5452 , http://hdl.handle.net/10962/d1005237
- Description: I investigate some algebras and calculi naturally associated with the symplectic and metric Clifford algebras. In particular, I reformulate the well known Lepage decomposition for the symplectic exterior algebra in geometrical form and present some new results relating to the simple subspaces of the decomposition. I then present an analogous decomposition for the symmetric exterior algebra with a metric. Finally, I extend this symmetric exterior algebra into a new calculus for the symmetric differential forms on a pseudo-Riemannian manifold. The importance of this calculus lies in its potential for the description of bosonic systems in Quantum Theory.
- Full Text:
- Authors: Russell, Neil Eric
- Date: 1993
- Subjects: Symplectic manifolds Geometry, Differential Geometric quantization Quantum theory Clifford algebras
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5452 , http://hdl.handle.net/10962/d1005237
- Description: I investigate some algebras and calculi naturally associated with the symplectic and metric Clifford algebras. In particular, I reformulate the well known Lepage decomposition for the symplectic exterior algebra in geometrical form and present some new results relating to the simple subspaces of the decomposition. I then present an analogous decomposition for the symmetric exterior algebra with a metric. Finally, I extend this symmetric exterior algebra into a new calculus for the symmetric differential forms on a pseudo-Riemannian manifold. The importance of this calculus lies in its potential for the description of bosonic systems in Quantum Theory.
- Full Text:
A critical analysis of problems encountered by senior secondary school pupils in the reading and interpretation of 1:50,000 topographical maps and aerial photographs with special reference to black pupils in Transkei
- Authors: Ndlwana, Monica
- Date: 1992
- Subjects: Maps -- Study and teaching (Secondary) Geography -- South Africa -- Transkei -- Study and teaching (Secondary) Black people -- Education -- South Africa -- Transkei
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1470 , http://hdl.handle.net/10962/d1003351
- Description: Mapwork is an established part of the geography curriculum, and yet it poses particular problems for pupils and teachers. Maps participate in a complex system of graphic communication: the conceptual abstraction involved in the reading and interpretation of maps requires on the part of pupils a high degree of cognitive and perceptual development; teachers, too, often experience considerable difficulty in imparting the skills necessary for graphic literacy (graphicacy). The peculiar difficulties associated with map reading and the poor performance of pupils in this area have regrettably encouraged an attitude which dismisses mapwork as irrelevant or dispensable in geographical education. Yet graphicacy is essential not only in the learning of geography but in the overall cognitive development of the child, and therefore cannot be excluded from the curriculum. This study attempts to identify some of the specific difficulties experienced by pupils in their attempts to read and interpret maps, and to trace the origin of these difficulties. It argues that the complexity and sophistication of the skills necessary to interpret topographical maps and aerial photographs, for instance, should not be underestimated. Teachers need to be made aware of how pupils acquire map reading skills and of the problems they encounter during this process, so that teaching programmes commensurate with pupils' level of cognitive development can be formulated. It is also important that mapwork be taught in as practical a manner as possible. The findings and recommendations of this study have implications for geography teachers, textbook writers and educational authorities, especially those involved in curriculum and syllabus design.
- Full Text:
- Authors: Ndlwana, Monica
- Date: 1992
- Subjects: Maps -- Study and teaching (Secondary) Geography -- South Africa -- Transkei -- Study and teaching (Secondary) Black people -- Education -- South Africa -- Transkei
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1470 , http://hdl.handle.net/10962/d1003351
- Description: Mapwork is an established part of the geography curriculum, and yet it poses particular problems for pupils and teachers. Maps participate in a complex system of graphic communication: the conceptual abstraction involved in the reading and interpretation of maps requires on the part of pupils a high degree of cognitive and perceptual development; teachers, too, often experience considerable difficulty in imparting the skills necessary for graphic literacy (graphicacy). The peculiar difficulties associated with map reading and the poor performance of pupils in this area have regrettably encouraged an attitude which dismisses mapwork as irrelevant or dispensable in geographical education. Yet graphicacy is essential not only in the learning of geography but in the overall cognitive development of the child, and therefore cannot be excluded from the curriculum. This study attempts to identify some of the specific difficulties experienced by pupils in their attempts to read and interpret maps, and to trace the origin of these difficulties. It argues that the complexity and sophistication of the skills necessary to interpret topographical maps and aerial photographs, for instance, should not be underestimated. Teachers need to be made aware of how pupils acquire map reading skills and of the problems they encounter during this process, so that teaching programmes commensurate with pupils' level of cognitive development can be formulated. It is also important that mapwork be taught in as practical a manner as possible. The findings and recommendations of this study have implications for geography teachers, textbook writers and educational authorities, especially those involved in curriculum and syllabus design.
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Environmental physiology of the intertidal limpets Patella (Prosobranchia) and Siphonaria (Pulmonata)
- Authors: Marshall, David John
- Date: 1992
- Subjects: Prosobranchia Pulmonata Patellidae Siphonaria Limpets
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5686 , http://hdl.handle.net/10962/d1005372
- Description: Physiological response to environmental change is examined in species of the intertidal limpets, Patella (Prosobranchia) and Siphonaria (Pulmonata). Characteristics of heart beat were determined using impedance pneumography and these are described. Heart rate of P. granularis is related to temperature and body size, and cardiac arrest in this limpet is apparently stress-related. Siphonaria oculus may exhibit a temperature-independent, extreme, and often prolonged bradycardia (<10 beats/min). When measured shortly after aerial exposure, heart rate and oxygen consumption of the above limpet species are closely correlated. The relationships of aerial oxygen consumption with body weight and ambient temperature were determined for the above high shore species of limpet. Both have low aerial rates of oxygen consumption relative to low shore limpet species, and their QlO values decrease with increasing temperature. Diel field recordings of heart rate of S. oculus, taken during summer and winter, suggest absence of temperature acclimation, and this was also shown for oxygen consumption at high aerial temperatures (30°C) in laboratory experiments. Oxygen consumption of P. granularis is partially temperature compensated temperature acclimation). In air, even though S. oculus loses water faster, it shows greater tolerance of water loss and survives longer than P. granularis. Prolonged aerial exposure of S. oculus leads to depression of heart rate and of V02 (down to 18% of the pre-exposure rate), responses interpreted as representing adaptive metabolic rate depression. In P. granularis aerial heart rate remains constant and V02 never falls below IX 38% of pre-exposure rate. This reduction in V02 in air is considered as being stress-related, resulting from impairment of oxygen uptake. In declining oxygen tension S. capensis shows a better capacity for oxyregulation than P. granularis. On exposure to hypoxia, sand-inundation and hyposalinity, S. capensis may show typical bradycardia ( <10 beats/min), suggesting depression of aerobic metabolism, and on return to pre-exposure conditions there is no overshoot of heart rate, suggesting absence of oxygen debt. The effect of hypoxia, sand-inundation and hyposalinity on heart rate of P. granularis is variable; this becomes depressed and is often interspersed with extended cardiac arrest. When conditions are normalized, this species exhibits a clear overshoot of heart rate. The significance of differences in physiological response between patellid and siphonariid limpets is discussed with regard to their habitat segregation, particularly in the upper-shore zone (open rock and tidal pools) and sand-inundated rock substrata, where only siphonariid limpets may be found. While not previously characterized in marine gastropods, metabolic rate depression by Siphonaria, through facilitating isolation and conserving food reserves, is suggested as a key factor determining their distribution in physico-chemically more extreme and variable intertidal habitats.
- Full Text:
- Authors: Marshall, David John
- Date: 1992
- Subjects: Prosobranchia Pulmonata Patellidae Siphonaria Limpets
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5686 , http://hdl.handle.net/10962/d1005372
- Description: Physiological response to environmental change is examined in species of the intertidal limpets, Patella (Prosobranchia) and Siphonaria (Pulmonata). Characteristics of heart beat were determined using impedance pneumography and these are described. Heart rate of P. granularis is related to temperature and body size, and cardiac arrest in this limpet is apparently stress-related. Siphonaria oculus may exhibit a temperature-independent, extreme, and often prolonged bradycardia (<10 beats/min). When measured shortly after aerial exposure, heart rate and oxygen consumption of the above limpet species are closely correlated. The relationships of aerial oxygen consumption with body weight and ambient temperature were determined for the above high shore species of limpet. Both have low aerial rates of oxygen consumption relative to low shore limpet species, and their QlO values decrease with increasing temperature. Diel field recordings of heart rate of S. oculus, taken during summer and winter, suggest absence of temperature acclimation, and this was also shown for oxygen consumption at high aerial temperatures (30°C) in laboratory experiments. Oxygen consumption of P. granularis is partially temperature compensated temperature acclimation). In air, even though S. oculus loses water faster, it shows greater tolerance of water loss and survives longer than P. granularis. Prolonged aerial exposure of S. oculus leads to depression of heart rate and of V02 (down to 18% of the pre-exposure rate), responses interpreted as representing adaptive metabolic rate depression. In P. granularis aerial heart rate remains constant and V02 never falls below IX 38% of pre-exposure rate. This reduction in V02 in air is considered as being stress-related, resulting from impairment of oxygen uptake. In declining oxygen tension S. capensis shows a better capacity for oxyregulation than P. granularis. On exposure to hypoxia, sand-inundation and hyposalinity, S. capensis may show typical bradycardia ( <10 beats/min), suggesting depression of aerobic metabolism, and on return to pre-exposure conditions there is no overshoot of heart rate, suggesting absence of oxygen debt. The effect of hypoxia, sand-inundation and hyposalinity on heart rate of P. granularis is variable; this becomes depressed and is often interspersed with extended cardiac arrest. When conditions are normalized, this species exhibits a clear overshoot of heart rate. The significance of differences in physiological response between patellid and siphonariid limpets is discussed with regard to their habitat segregation, particularly in the upper-shore zone (open rock and tidal pools) and sand-inundated rock substrata, where only siphonariid limpets may be found. While not previously characterized in marine gastropods, metabolic rate depression by Siphonaria, through facilitating isolation and conserving food reserves, is suggested as a key factor determining their distribution in physico-chemically more extreme and variable intertidal habitats.
- Full Text:
The place of classical civilization in the school curriculum
- Authors: Morton, Anne Caroline
- Date: 1985
- Subjects: Education -- Curricula -- South Africa Civilization, Classical -- Study and teaching Latin language -- History -- 20th century Latin language -- Study and teaching (Secondary) -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1378 , http://hdl.handle.net/10962/d1001444
- Description: Classical Studies, as a subject, has not been seriously presented in many schools until fairly recently. Britain initiated the introduction of Classical Studies to the school curriculum in 1974, and interest has continued to grow steadily in other countries like America, New Zealand, Australia and Canada. This thesis was started on the assumption that this entirely new subject could be introduced into the curriculum for standard six and seven pupils at South African schools, for reasons which will be given later. As work continued on the thesis, the 1985 syllabus for Latin lent it further impetus. Some of the implications of the new Latin syllabus will be considered in the conclusion (Introduction, p. 6)
- Full Text:
- Authors: Morton, Anne Caroline
- Date: 1985
- Subjects: Education -- Curricula -- South Africa Civilization, Classical -- Study and teaching Latin language -- History -- 20th century Latin language -- Study and teaching (Secondary) -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1378 , http://hdl.handle.net/10962/d1001444
- Description: Classical Studies, as a subject, has not been seriously presented in many schools until fairly recently. Britain initiated the introduction of Classical Studies to the school curriculum in 1974, and interest has continued to grow steadily in other countries like America, New Zealand, Australia and Canada. This thesis was started on the assumption that this entirely new subject could be introduced into the curriculum for standard six and seven pupils at South African schools, for reasons which will be given later. As work continued on the thesis, the 1985 syllabus for Latin lent it further impetus. Some of the implications of the new Latin syllabus will be considered in the conclusion (Introduction, p. 6)
- Full Text:
An ecophysiological study of the effects of changes in salinity and temperature on the distribution of Macrobrachium Petersi (Hilgendorf) in the Keiskamma river and estuary
- Read, Graeme Hamilton Leonard
- Authors: Read, Graeme Hamilton Leonard
- Date: 1982
- Subjects: Macrobrachium -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5804 , http://hdl.handle.net/10962/d1006304
- Description: Summary: The distribution of adult, juvenile, post larval and larval Macrobrachium petersi (Hilgendorf) was studied in relation to temperature and salinity in the Keiskamma river and estuary from May 1979 to May 1981. M. petersi is a subtropical species, which confined activity of all stages in the field to the summer months. Variable freshwater discharge and tidal effects determined the salinity and temperature profiles in the middle and upper reaches of the Keiskamma estuary. Thus, a dry 1979/80 summer and a wet 1980/81 summer markedly influenced the abundance and distribution of adult M. petersi in the river and estuary respectively. Adult M. petersi migrate to the estuary under flooding conditions and upstream in response to elevated salinities. Although M. petersi has nine larval stages only a preponderance of stage I were caught in the field. These portray a distinct nocturnal and diurnal distribution pattern which is influenced by salinity, especially under stratified conditions. After flooding the larvae show an affinity for salt front regions and reach these by remaining in the water column on the ebbing tide. A substantial drop in abundance downstream from the salt front suggests that the larvae loose their planktonic phase which is an effective retention mechanism, and confines larval development to the middle and upper reaches of the estuary. Post larvae were caught towards the end of the 1981 breeding season which indicates that complete larval development takes place in the estuary. A post larval migration to freshwater, which reaches a peak in February and March, was monitored. Thus both the freshwater and estuarine environments form an inseparable link in the life cycle of M. petersi. The distribution of stage I larvae in the Keiskamma estuary suggested that salinity played a role in development. The fact that other larval stages were not found emphasised the necessity for a quantitative laboratory investigation to determine the importance of salinity in the developmental history of M. petersi larvae and post larvae. However, the modifying influence of temperature could not be ignored so a multivariable approach was adopted. This, together with a surface response technique, aided the interpretation of the effect of a variety of combinations of salinity and temperature on ecdysis to stage II, larval survival and requirements for metamorphosis to post larvae. It was estimated that the minimum salinity requirement for complete larval development, within a temperature range from 18 to 30⁰C was 8%₀, although ecdysis to stage II and metamorphosis to post larvae could occur in salinities less than this value. Despite the euryhalinity of the larvae, the behaviour of adult M. petersi to an increase in salinity and the affinity of stage I larvae to salt front regions restricted development to the upper reaches of the estuary. This is discussed as an adaptation which not only ensures retention within the estuary but favours recruitment to the adult population in freshwater. The osmoregulatory patterns of larval, post larval, juvenile and adult M. petersi correlated with their distribution. These were approximated by a cubic polynomial which enabled the different patterns to be compared. The larval stages investigated (I, II, V & IX) displayed a remarkable capacity to regulate which was strongest in stage I as these could regulate in both freshwater and 35%₀. The ability to regulate in freshwater was lost hereafter but regained in the post larvae, which also regulated in 35%₀. Juveniles (caught at the ebb and flow) displayed a similar regulatory pattern to the adults and "hyposmoconformed" in salinities beyond the isosmotic point as the need to regulate in 35%₀ was no longer necessary. The osmoregulatory capacity of M. petersi larvae in relation to other decapod larvae is discussed. Marine transport of the euryhaline larval and post larval stages accounts for the distribution of M. petersi along the South African coastline. However, south of 31°S latitude the sea-surface temperature decreases abruptly. This region coincides with the southern limit of the distribution of M. petersi. Although larval M. petersi can tolerate high salinity (35%₀) in combination with low temperature, the post larvae cannot, which is likely to account for their restricted southern distribution. The genus Macrobrachium are in the process of invading freshwater. The possible course that this might have taken has been discussed in the light of available evidence as well as the findings of this study.
- Full Text:
- Authors: Read, Graeme Hamilton Leonard
- Date: 1982
- Subjects: Macrobrachium -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5804 , http://hdl.handle.net/10962/d1006304
- Description: Summary: The distribution of adult, juvenile, post larval and larval Macrobrachium petersi (Hilgendorf) was studied in relation to temperature and salinity in the Keiskamma river and estuary from May 1979 to May 1981. M. petersi is a subtropical species, which confined activity of all stages in the field to the summer months. Variable freshwater discharge and tidal effects determined the salinity and temperature profiles in the middle and upper reaches of the Keiskamma estuary. Thus, a dry 1979/80 summer and a wet 1980/81 summer markedly influenced the abundance and distribution of adult M. petersi in the river and estuary respectively. Adult M. petersi migrate to the estuary under flooding conditions and upstream in response to elevated salinities. Although M. petersi has nine larval stages only a preponderance of stage I were caught in the field. These portray a distinct nocturnal and diurnal distribution pattern which is influenced by salinity, especially under stratified conditions. After flooding the larvae show an affinity for salt front regions and reach these by remaining in the water column on the ebbing tide. A substantial drop in abundance downstream from the salt front suggests that the larvae loose their planktonic phase which is an effective retention mechanism, and confines larval development to the middle and upper reaches of the estuary. Post larvae were caught towards the end of the 1981 breeding season which indicates that complete larval development takes place in the estuary. A post larval migration to freshwater, which reaches a peak in February and March, was monitored. Thus both the freshwater and estuarine environments form an inseparable link in the life cycle of M. petersi. The distribution of stage I larvae in the Keiskamma estuary suggested that salinity played a role in development. The fact that other larval stages were not found emphasised the necessity for a quantitative laboratory investigation to determine the importance of salinity in the developmental history of M. petersi larvae and post larvae. However, the modifying influence of temperature could not be ignored so a multivariable approach was adopted. This, together with a surface response technique, aided the interpretation of the effect of a variety of combinations of salinity and temperature on ecdysis to stage II, larval survival and requirements for metamorphosis to post larvae. It was estimated that the minimum salinity requirement for complete larval development, within a temperature range from 18 to 30⁰C was 8%₀, although ecdysis to stage II and metamorphosis to post larvae could occur in salinities less than this value. Despite the euryhalinity of the larvae, the behaviour of adult M. petersi to an increase in salinity and the affinity of stage I larvae to salt front regions restricted development to the upper reaches of the estuary. This is discussed as an adaptation which not only ensures retention within the estuary but favours recruitment to the adult population in freshwater. The osmoregulatory patterns of larval, post larval, juvenile and adult M. petersi correlated with their distribution. These were approximated by a cubic polynomial which enabled the different patterns to be compared. The larval stages investigated (I, II, V & IX) displayed a remarkable capacity to regulate which was strongest in stage I as these could regulate in both freshwater and 35%₀. The ability to regulate in freshwater was lost hereafter but regained in the post larvae, which also regulated in 35%₀. Juveniles (caught at the ebb and flow) displayed a similar regulatory pattern to the adults and "hyposmoconformed" in salinities beyond the isosmotic point as the need to regulate in 35%₀ was no longer necessary. The osmoregulatory capacity of M. petersi larvae in relation to other decapod larvae is discussed. Marine transport of the euryhaline larval and post larval stages accounts for the distribution of M. petersi along the South African coastline. However, south of 31°S latitude the sea-surface temperature decreases abruptly. This region coincides with the southern limit of the distribution of M. petersi. Although larval M. petersi can tolerate high salinity (35%₀) in combination with low temperature, the post larvae cannot, which is likely to account for their restricted southern distribution. The genus Macrobrachium are in the process of invading freshwater. The possible course that this might have taken has been discussed in the light of available evidence as well as the findings of this study.
- Full Text:
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