A comparison of the performance of three conceptual mathematical models of the rainfall-runoff process in the Mareetsane Catchment
- Authors: Stickells Peter S
- Date: 1979
- Subjects: Rain and rainfall Mathematical models South Africa Runoff
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4793 , http://hdl.handle.net/10962/d1001893
- Description: The objective of the thesis is to make a critical assessment of the performance of three relatively simple deterministic models of the rainfall-runoff process. The need to evaluate and compare deterministic models arises because of the large number of models which are available in the literature. A number of the available models would appear to be equally suitable for a given situation whereas many models are found to be valid only under the specific range of conditions for which they were developed. Therefore there is a need for guidelines to allow the most judicious selection of a model for a particular set of circumstances. The models used in the study will be tested in a semi-arid catchment to determine their applicability under ephemeral flow conditions
- Full Text:
- Date Issued: 1979
- Authors: Stickells Peter S
- Date: 1979
- Subjects: Rain and rainfall Mathematical models South Africa Runoff
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4793 , http://hdl.handle.net/10962/d1001893
- Description: The objective of the thesis is to make a critical assessment of the performance of three relatively simple deterministic models of the rainfall-runoff process. The need to evaluate and compare deterministic models arises because of the large number of models which are available in the literature. A number of the available models would appear to be equally suitable for a given situation whereas many models are found to be valid only under the specific range of conditions for which they were developed. Therefore there is a need for guidelines to allow the most judicious selection of a model for a particular set of circumstances. The models used in the study will be tested in a semi-arid catchment to determine their applicability under ephemeral flow conditions
- Full Text:
- Date Issued: 1979
A situational survey of Siyazondla homestead food production proogramme and food security, poverty alleviation in selected communities of Nkonkobe Local Municipality of the Eastern Cape
- Authors: Phezisa, Bulelani
- Date: 2016
- Subjects: Food security -- South Africa -- Eastern Cape Food supply -- South Africa -- Eastern Cape Poverty -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2392 , vital:27795
- Description: People living in rural areas are continually losing their value, dignity, ubuntu and rural nature of livelihood. Agriculture in these areas characterises the nature of rural livelihood. Traditionally, people living in rural areas were highly dependent on their production from gardens for food, income (barter exchange), and other social activities. Nowadays, that motive and interest is no longer operating at its full potential, so to revive that history and nature, household (homestead) production, certain programmes were introduced to greatly improved the standard of living of the poor, and it has proved to have an impact as it has generated income, and created food stability and employment through the project. Home gardens are there and can be used as the method and the strategy toward improvement and development of the people around the world, more especial to developing countries. Certain programmes that are initiated for acting against the challenges faced by rural people have failed to materialise and operate on their fully potential. The Siyazondla homestead food production programme is the one of the programmes practiced by the government of South Africa to act against such challenges, affecting especially poor people. This study was aimed at assessing the role of Siyazondla homestead food production programme in food security and poverty alleviation in selected communities of Nkonkobe local municipality of the Eastern Cape. It took the form of a case study in Msobomvu, Ngcothoyi and Binfield locations. The Nkonkobe local municipality is demarcated into five major areas: Middledrift, Alice, Seymour, Fort Beaufort and Balfour. The study sample was collected from beneficiaries and non-beneficiaries of the Siyazondla programme. The sample size was 90 respondents, from which in one area, a 15 beneficiaries and anticipated non- beneficiaries were targeted. The target sample from each village was collected from 15 beneficiaries and non-beneficiaries. Many farmers from the study area benefited from the programme, though a limited number was targeted. Therefore, a probability sampling was applied and employed, where there were more than required number of beneficiaries of the programme and anticipated beneficiaries of the programme. The study was effectively and efficiently carried out and achieved with the use of personal interviewing of the recipients by use of questionnaires. The study was analysed by a computerised programme of analyses called SPSS v.2.1 and excel. The objectives of the study based on food security, poverty alleviation and reduction, and also improving nutritious status. The finding of the research clearly indicates the outcome of the programme on livelihood basis of the beneficiaries. Some of the objectives of the programme were achieved, such as food security and nutritious levels, whilst other objectives had shortcomings. The finding of the study also shows that programme, though had original benefits but also there are the anticipated and probable benefits of the programme Siyazondla, such as income, skill of farming, improving social status, and there are some possibilities when the programme is properly implemented. Though the majority of people are concentrated in rural areas, the programme on its own had shortcoming to meet needs of the whole population, as food insecurity, unemployment and poverty are taking its course. The programme on its own had shortcoming such as lack of adequate resource and as results, very few people benefited from the programme. Another shortcoming of the programme is the effectiveness of agricultural extension personnel to certain aspect such as marketing of farmers produce and proper monitoring and evaluation of the programme. Therefore, in the long run programmes of this nature are promising, there will be some development and improvement toward growth and better standards of livelihood. It is through this study that had to assess the structure, procedure, strategies implemented of the programme and impact of the programme to both beneficiaries and anticipated beneficiaries of the programme.
- Full Text:
- Date Issued: 2016
- Authors: Phezisa, Bulelani
- Date: 2016
- Subjects: Food security -- South Africa -- Eastern Cape Food supply -- South Africa -- Eastern Cape Poverty -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2392 , vital:27795
- Description: People living in rural areas are continually losing their value, dignity, ubuntu and rural nature of livelihood. Agriculture in these areas characterises the nature of rural livelihood. Traditionally, people living in rural areas were highly dependent on their production from gardens for food, income (barter exchange), and other social activities. Nowadays, that motive and interest is no longer operating at its full potential, so to revive that history and nature, household (homestead) production, certain programmes were introduced to greatly improved the standard of living of the poor, and it has proved to have an impact as it has generated income, and created food stability and employment through the project. Home gardens are there and can be used as the method and the strategy toward improvement and development of the people around the world, more especial to developing countries. Certain programmes that are initiated for acting against the challenges faced by rural people have failed to materialise and operate on their fully potential. The Siyazondla homestead food production programme is the one of the programmes practiced by the government of South Africa to act against such challenges, affecting especially poor people. This study was aimed at assessing the role of Siyazondla homestead food production programme in food security and poverty alleviation in selected communities of Nkonkobe local municipality of the Eastern Cape. It took the form of a case study in Msobomvu, Ngcothoyi and Binfield locations. The Nkonkobe local municipality is demarcated into five major areas: Middledrift, Alice, Seymour, Fort Beaufort and Balfour. The study sample was collected from beneficiaries and non-beneficiaries of the Siyazondla programme. The sample size was 90 respondents, from which in one area, a 15 beneficiaries and anticipated non- beneficiaries were targeted. The target sample from each village was collected from 15 beneficiaries and non-beneficiaries. Many farmers from the study area benefited from the programme, though a limited number was targeted. Therefore, a probability sampling was applied and employed, where there were more than required number of beneficiaries of the programme and anticipated beneficiaries of the programme. The study was effectively and efficiently carried out and achieved with the use of personal interviewing of the recipients by use of questionnaires. The study was analysed by a computerised programme of analyses called SPSS v.2.1 and excel. The objectives of the study based on food security, poverty alleviation and reduction, and also improving nutritious status. The finding of the research clearly indicates the outcome of the programme on livelihood basis of the beneficiaries. Some of the objectives of the programme were achieved, such as food security and nutritious levels, whilst other objectives had shortcomings. The finding of the study also shows that programme, though had original benefits but also there are the anticipated and probable benefits of the programme Siyazondla, such as income, skill of farming, improving social status, and there are some possibilities when the programme is properly implemented. Though the majority of people are concentrated in rural areas, the programme on its own had shortcoming to meet needs of the whole population, as food insecurity, unemployment and poverty are taking its course. The programme on its own had shortcoming such as lack of adequate resource and as results, very few people benefited from the programme. Another shortcoming of the programme is the effectiveness of agricultural extension personnel to certain aspect such as marketing of farmers produce and proper monitoring and evaluation of the programme. Therefore, in the long run programmes of this nature are promising, there will be some development and improvement toward growth and better standards of livelihood. It is through this study that had to assess the structure, procedure, strategies implemented of the programme and impact of the programme to both beneficiaries and anticipated beneficiaries of the programme.
- Full Text:
- Date Issued: 2016
A systematic study of Berkheya and allies (Compositae)
- Authors: Phaliso, Ntombifikile
- Date: 2013
- Subjects: Compositae -- Africa, Southern , Daisies -- Africa, Southern , Compositae -- Phylogeny -- Africa, Southern , Compositae -- Geographical distribution -- Africa, Southern , Compositae -- Classification -- Africa, Southern , Cladistic analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4179 , http://hdl.handle.net/10962/d1003054
- Description: Berkheya Ehrh. is a genus of daisies in the tribe Arctotideae, subtribe Gorteriinae with over 80 species, most of which occur in southern Africa. This genus has centres of diversity associated with the montane regions of South Africa, including the Drakensberg Alpine Centre and Mpumalanga escarpment regions. Previous molecular and morphological studies indicate that Berkheya is paraphyletic. I present phylogenies based on nrDNA (ITS; Internal Transcribed Spacer) and cpDNA (psbA-trnH) sequence data analysed with Bayesian Inference and Parsimony. A phylogeny of combined cp- and nrDNA is also presented. These phylogenies are used to assess generic limits and to investigate the biogeographic patterns of Berkheya and its allies. The ITS phylogeny shows five well supported clades of Berkheya, two of which (Clades I and 2) are monophyletic summer rainfall region clades. Clades 3 to 5 are all paraphyletic winter rainfall clades with Cullumia occurring in the third clade, Cuspida occurring in the fourth and Didelta in Clade 5. Both psbA-trnH and combined phylogenies show concordance with the clade distribution shown in the ITS phylogeny. The ITS phylogeny was used to analyse correspondence with Roessler’s (1959) Series. It was found that the phylogeny showed considerable agreement with Roessler’s series, but B. bipinnatifida and B. spinosa of Series Speciosae may require some revision as well as taxa of monotypic series Cruciatae and Angustae. It is suggested that the latter series be merged with Cullumia species to form a single series. Some consideration should be taken to include Didelta species into Series Fruticosae as Didelta occurs in subclade 5b of Clade 5 with other Series Fruticosae taxa. Achene morphology was examined from species from each of the five clades to investigate the relationships of Berkheya and its allies, as well as to determine if there were any consistent achene features for each clade. The structure of surface cells on the fruit, the presence, absence and morphology of twin hairs as well as the structure of the pappus scales were found to be most useful in reflecting phylogenetic relationships within the clades. When compared with the clades of the ITS phylogeny, achene morphology showed consistent characters between taxa occurring in the same clades. As the most comprehensive study involving Berkheya, this phylogenenetic investigation was able to confirm that Berkheya is a paraphyletic genus with Didelta, Cullumia and Cuspida needing to be subsumed into Berkheya. An alternative classification is that taxa of Clade 5 could possibly be erected as an expanded Didelta, separate and sister to Berkheya.
- Full Text:
- Date Issued: 2013
- Authors: Phaliso, Ntombifikile
- Date: 2013
- Subjects: Compositae -- Africa, Southern , Daisies -- Africa, Southern , Compositae -- Phylogeny -- Africa, Southern , Compositae -- Geographical distribution -- Africa, Southern , Compositae -- Classification -- Africa, Southern , Cladistic analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4179 , http://hdl.handle.net/10962/d1003054
- Description: Berkheya Ehrh. is a genus of daisies in the tribe Arctotideae, subtribe Gorteriinae with over 80 species, most of which occur in southern Africa. This genus has centres of diversity associated with the montane regions of South Africa, including the Drakensberg Alpine Centre and Mpumalanga escarpment regions. Previous molecular and morphological studies indicate that Berkheya is paraphyletic. I present phylogenies based on nrDNA (ITS; Internal Transcribed Spacer) and cpDNA (psbA-trnH) sequence data analysed with Bayesian Inference and Parsimony. A phylogeny of combined cp- and nrDNA is also presented. These phylogenies are used to assess generic limits and to investigate the biogeographic patterns of Berkheya and its allies. The ITS phylogeny shows five well supported clades of Berkheya, two of which (Clades I and 2) are monophyletic summer rainfall region clades. Clades 3 to 5 are all paraphyletic winter rainfall clades with Cullumia occurring in the third clade, Cuspida occurring in the fourth and Didelta in Clade 5. Both psbA-trnH and combined phylogenies show concordance with the clade distribution shown in the ITS phylogeny. The ITS phylogeny was used to analyse correspondence with Roessler’s (1959) Series. It was found that the phylogeny showed considerable agreement with Roessler’s series, but B. bipinnatifida and B. spinosa of Series Speciosae may require some revision as well as taxa of monotypic series Cruciatae and Angustae. It is suggested that the latter series be merged with Cullumia species to form a single series. Some consideration should be taken to include Didelta species into Series Fruticosae as Didelta occurs in subclade 5b of Clade 5 with other Series Fruticosae taxa. Achene morphology was examined from species from each of the five clades to investigate the relationships of Berkheya and its allies, as well as to determine if there were any consistent achene features for each clade. The structure of surface cells on the fruit, the presence, absence and morphology of twin hairs as well as the structure of the pappus scales were found to be most useful in reflecting phylogenetic relationships within the clades. When compared with the clades of the ITS phylogeny, achene morphology showed consistent characters between taxa occurring in the same clades. As the most comprehensive study involving Berkheya, this phylogenenetic investigation was able to confirm that Berkheya is a paraphyletic genus with Didelta, Cullumia and Cuspida needing to be subsumed into Berkheya. An alternative classification is that taxa of Clade 5 could possibly be erected as an expanded Didelta, separate and sister to Berkheya.
- Full Text:
- Date Issued: 2013
An investigation on the effect of Russian wheat aphid (Diuraphis noxia Kurdjumov) population growth and feeding damage on selected barley (Hordeum vulgare L.) cultivars under ambient and elevated CO2
- Authors: Sacranie, Sattar Farouk
- Date: 2016
- Subjects: Russian wheat aphid -- Research -- South Africa Barley -- Disease and pest resistance -- South Africa Callose Aphids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/50311 , vital:25975
- Description: The Russian wheat aphid (RWA) (Diuraphis noxia Kurdjumov) is a major pest of cultivated small grains. It is particularly devastating because of is high reproductive rate which results in the growth of large populations which become damaging to its host plants. Development of resistant barley (Hordeum vulgare L.) cultivars is complicated as resistance is polygenic. As a result, the industry remains at risk now that the RWA has spread throughout South Africa. It has, as recently as, 2013, been identified in the SW Cape, which was previously geographically isolated. This is South Africa‟s principle barley growing region. Now a potentially huge problem exists. Therefore, it is imperative that an alternative to pesticide use is found. Testing potential innate resistance in barley cultivars is thus, critical. In this thesis, I present data on four barely cultivars where I have examined their resistance/ lack of resistance to three known RWA biotypes, RWASA1, RWASA2 and RWASA3. The barley varieties used were two economically important South African malt barley cultivars (S5 and SSG 564) along with two potentially RWA resistant Afghan accessions (CIho 4125 and CIho 4159). The RWA biotype population growth rates on each of the plants were determined over a 14 day period. The aim was to establish baseline data of the effects of RWA population growth on the host plants under ambient CO2 (380 – 400 ppm) conditions. The extent of RWA feeding damage was investigated at the cell level by examining saliva deposition and cell disruption using Transmission Electron Microscopy; at the tissue/vascular level using fluorescence microscopy, to determine the extent of callose formation; at a whole leaf level by recording percent chlorosis and leaf roll; and finally, at a whole plant level by measuring biomass loss.The experiments were repeated under elevated CO2 (450 ppm) to model any changes in RWA/plant interaction with respect to future climate change. The effects of an elevated CO2 environment and RWA feeding on host plant foliar N and C:N ratio were compared to ambient CO2 conditions, to provide a clearer picture of the potential nutrient drain that a feeding RWA colony exacts on its host. Of the varieties tested, the CIho accessions performed better than the two SA barley cultivars as the CIho accessions appeared to express a mild antibiosis resistance response as RWA populations, particularly those of RWASA1, were smaller than those observed on either S5 or SSG 564. In addition, less damage was evident in the two CIho accessions due to RWA feeding. II RWASA2 was the most virulent of the three RWA biotypes tested, followed by RWASA3 while RWASA1 was the least virulent. Under elevated CO2 conditions, RWA feeding damage was exacerbated but the trend of biotype virulence remained the same. Higher aphid population sizes were recorded under elevated CO2, meant that even the more resistant CIho accessions were overcome by the increased demand made by the larger aphid colonies on the host plants. The % foliar N data showed that under elevated CO2 aphid-free control plants had increased N levels in their leaves. Increased “food” supply (as shown by the increased N levels) therefore allowed significantly larger aphid populations to develop on the plants exposed to elevated CO2, due to improved nutrient status of the phloem sap taken up by RWA. The knock-on effect of a higher aphid population was increased cell disruption as a result of extensive probing, extensive formations of wound callose, with the result that phloem damage impeded nutrient flow through the vascular tissues which contributed to chlorosis and (eventually plant) death. The major conclusion from this study is that even a mild CO2 elevation resulted in an increase aphid population which may pose a severe and very real threat to a barley crop. Therefore, without effort to identify and deploy resistant barley cultivars, it could well be possible that future barley cultivation in South Africa may no longer be viable.
- Full Text:
- Date Issued: 2016
- Authors: Sacranie, Sattar Farouk
- Date: 2016
- Subjects: Russian wheat aphid -- Research -- South Africa Barley -- Disease and pest resistance -- South Africa Callose Aphids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/50311 , vital:25975
- Description: The Russian wheat aphid (RWA) (Diuraphis noxia Kurdjumov) is a major pest of cultivated small grains. It is particularly devastating because of is high reproductive rate which results in the growth of large populations which become damaging to its host plants. Development of resistant barley (Hordeum vulgare L.) cultivars is complicated as resistance is polygenic. As a result, the industry remains at risk now that the RWA has spread throughout South Africa. It has, as recently as, 2013, been identified in the SW Cape, which was previously geographically isolated. This is South Africa‟s principle barley growing region. Now a potentially huge problem exists. Therefore, it is imperative that an alternative to pesticide use is found. Testing potential innate resistance in barley cultivars is thus, critical. In this thesis, I present data on four barely cultivars where I have examined their resistance/ lack of resistance to three known RWA biotypes, RWASA1, RWASA2 and RWASA3. The barley varieties used were two economically important South African malt barley cultivars (S5 and SSG 564) along with two potentially RWA resistant Afghan accessions (CIho 4125 and CIho 4159). The RWA biotype population growth rates on each of the plants were determined over a 14 day period. The aim was to establish baseline data of the effects of RWA population growth on the host plants under ambient CO2 (380 – 400 ppm) conditions. The extent of RWA feeding damage was investigated at the cell level by examining saliva deposition and cell disruption using Transmission Electron Microscopy; at the tissue/vascular level using fluorescence microscopy, to determine the extent of callose formation; at a whole leaf level by recording percent chlorosis and leaf roll; and finally, at a whole plant level by measuring biomass loss.The experiments were repeated under elevated CO2 (450 ppm) to model any changes in RWA/plant interaction with respect to future climate change. The effects of an elevated CO2 environment and RWA feeding on host plant foliar N and C:N ratio were compared to ambient CO2 conditions, to provide a clearer picture of the potential nutrient drain that a feeding RWA colony exacts on its host. Of the varieties tested, the CIho accessions performed better than the two SA barley cultivars as the CIho accessions appeared to express a mild antibiosis resistance response as RWA populations, particularly those of RWASA1, were smaller than those observed on either S5 or SSG 564. In addition, less damage was evident in the two CIho accessions due to RWA feeding. II RWASA2 was the most virulent of the three RWA biotypes tested, followed by RWASA3 while RWASA1 was the least virulent. Under elevated CO2 conditions, RWA feeding damage was exacerbated but the trend of biotype virulence remained the same. Higher aphid population sizes were recorded under elevated CO2, meant that even the more resistant CIho accessions were overcome by the increased demand made by the larger aphid colonies on the host plants. The % foliar N data showed that under elevated CO2 aphid-free control plants had increased N levels in their leaves. Increased “food” supply (as shown by the increased N levels) therefore allowed significantly larger aphid populations to develop on the plants exposed to elevated CO2, due to improved nutrient status of the phloem sap taken up by RWA. The knock-on effect of a higher aphid population was increased cell disruption as a result of extensive probing, extensive formations of wound callose, with the result that phloem damage impeded nutrient flow through the vascular tissues which contributed to chlorosis and (eventually plant) death. The major conclusion from this study is that even a mild CO2 elevation resulted in an increase aphid population which may pose a severe and very real threat to a barley crop. Therefore, without effort to identify and deploy resistant barley cultivars, it could well be possible that future barley cultivation in South Africa may no longer be viable.
- Full Text:
- Date Issued: 2016
Assessment of rangeland condition and evaluation of farmers' perception in Njwaxa and Mbizana communal rangelands of the Eastern Cape, South Africa
- Authors: Ngcofe, Odwa Armstrong
- Date: 2016
- Subjects: Rangelands -- South Africa -- Eastern Cape Land tenure -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/13259 , vital:39627
- Description: This study was conducted to determine of rangeland condition in terms of botanical composition, soil nutrient composition, and also to evaluate farmers’ perception on rangeland condition and degradation in two communal villages Njwaxa and Mbizana in the Eastern Cape Province of South Africa in 2014. A Structured questionnaire consisting of close and open-ended questions was used to investigate farmers’ perceptions on range condition, land degradation, and their causes. Fifty households with livestock were randomly selected in two communal areas of Middledrift (i.e. Njwaxa and Mbizana). Respondents of 21 years and above were selected. For assessment of range condition three homogeneous vegetation units (HVU) were demarcated in all study sites, namely slope; valley and toplands were demarcated and sub-divided into four 100m x 50m replicates. In each replicate, four 100m transects were laid parallel to each other 25m apart 1m2 quadrant was systematically located four times along each transect for herbaceous vegetation and soil sampling. The step point method was employed to determine herbaceous species composition and basal cover. A 400m2 belt transect was used to determine woody vegetation composition, density and tree equivalents in each HVU. The germination method was employed for soil seed bank composition and plant density. The soil micro and macro nutrients (N, P, K OC, Ca, Mg, Zn, Cu and Mn) and pH were also analyzed The majority of the respondents were between the ages of 51-60 years. Most of the farmers had more cattle (38percent) than goats (32percent) and sheep (30percent). Livestock numbers were perceived to have declined over the previous 20 years by the majority of respondents (96percent). The respondents indicated that their rangelands were mainly used for browsing (1.37), fire wood (2.01), building and fencing (2.63) and medical purposes (3.66). All the respondents indicated that their rangelands were highly degraded. Sheet erosion (50percent) was perceived to be the major type of soil erosion indicator mentioned by the farmers, followed by gully erosion (29percent) and rill erosion (21percent). The rangeland was dominated by Increaser II (pioneer) (63.2 percent) grass species followed by Decreaser (mesophytes) species (26.3percent). Digitaria eriantha in the valley (53.5 percent) was significantly higher (p<0.05) than both in the top (10.5percent) and sloppy areas (33.5percent) at Njwaxa communal rangeland, the abundance of D. eriantha was significantly higher (p<0.05) than top and valley in Mbizana communal rangeland. The results showed that soil seed banks were dominated by perennials, followed by annuals and biennial species being least abundant. The dominant forb Jamebrittenia c.f. albanesis was significantly higher (p<0.05) in both slopes (6.65percent) and toplands (7.34percent) than in the valley (3.15). The second most dominant species Puesdognaphalium undulata was significantly higher (p<0.05) in topland areas (6percent) than in valley bottom (3.8percent) and sloppy areas (4.3percent). The results of soil nutrients revealed no significant differences (p>0.05) in the concentration of OC, Ca, and Mg between the communities and seasons. Phosphorus (P) was significantly higher (p<0.05) in winter (concentrations) in most of the sites, except the top sites of Mbizana where summer concentration of P was significantly higher than winter. Potassium (K) was significantly higher (p<0.05) in summer than in winter in most of the HVUs, except the topland areas of Njwaxa and Mbizana sloppy areas where there were no significant differences (p>0.05) in the concentration of K. Soil pH did not display any significant differences (p>0.05) between communities and sites. The mean soil pH recorded in this study was 5.4 implying the soils of Njwaxa and Mbizana communities were acidic. It is evident that communal farmers are well aware of their rangeland condition, changes occurring in their rangelands, their causes and are capable of suggesting some solutions in controlling the declining condition of the rangelands. This study has shown the importance of engaging farmers’ inputs in range assessment since those are people bearing the consequences of rangeland degradation.
- Full Text:
- Date Issued: 2016
- Authors: Ngcofe, Odwa Armstrong
- Date: 2016
- Subjects: Rangelands -- South Africa -- Eastern Cape Land tenure -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/13259 , vital:39627
- Description: This study was conducted to determine of rangeland condition in terms of botanical composition, soil nutrient composition, and also to evaluate farmers’ perception on rangeland condition and degradation in two communal villages Njwaxa and Mbizana in the Eastern Cape Province of South Africa in 2014. A Structured questionnaire consisting of close and open-ended questions was used to investigate farmers’ perceptions on range condition, land degradation, and their causes. Fifty households with livestock were randomly selected in two communal areas of Middledrift (i.e. Njwaxa and Mbizana). Respondents of 21 years and above were selected. For assessment of range condition three homogeneous vegetation units (HVU) were demarcated in all study sites, namely slope; valley and toplands were demarcated and sub-divided into four 100m x 50m replicates. In each replicate, four 100m transects were laid parallel to each other 25m apart 1m2 quadrant was systematically located four times along each transect for herbaceous vegetation and soil sampling. The step point method was employed to determine herbaceous species composition and basal cover. A 400m2 belt transect was used to determine woody vegetation composition, density and tree equivalents in each HVU. The germination method was employed for soil seed bank composition and plant density. The soil micro and macro nutrients (N, P, K OC, Ca, Mg, Zn, Cu and Mn) and pH were also analyzed The majority of the respondents were between the ages of 51-60 years. Most of the farmers had more cattle (38percent) than goats (32percent) and sheep (30percent). Livestock numbers were perceived to have declined over the previous 20 years by the majority of respondents (96percent). The respondents indicated that their rangelands were mainly used for browsing (1.37), fire wood (2.01), building and fencing (2.63) and medical purposes (3.66). All the respondents indicated that their rangelands were highly degraded. Sheet erosion (50percent) was perceived to be the major type of soil erosion indicator mentioned by the farmers, followed by gully erosion (29percent) and rill erosion (21percent). The rangeland was dominated by Increaser II (pioneer) (63.2 percent) grass species followed by Decreaser (mesophytes) species (26.3percent). Digitaria eriantha in the valley (53.5 percent) was significantly higher (p<0.05) than both in the top (10.5percent) and sloppy areas (33.5percent) at Njwaxa communal rangeland, the abundance of D. eriantha was significantly higher (p<0.05) than top and valley in Mbizana communal rangeland. The results showed that soil seed banks were dominated by perennials, followed by annuals and biennial species being least abundant. The dominant forb Jamebrittenia c.f. albanesis was significantly higher (p<0.05) in both slopes (6.65percent) and toplands (7.34percent) than in the valley (3.15). The second most dominant species Puesdognaphalium undulata was significantly higher (p<0.05) in topland areas (6percent) than in valley bottom (3.8percent) and sloppy areas (4.3percent). The results of soil nutrients revealed no significant differences (p>0.05) in the concentration of OC, Ca, and Mg between the communities and seasons. Phosphorus (P) was significantly higher (p<0.05) in winter (concentrations) in most of the sites, except the top sites of Mbizana where summer concentration of P was significantly higher than winter. Potassium (K) was significantly higher (p<0.05) in summer than in winter in most of the HVUs, except the topland areas of Njwaxa and Mbizana sloppy areas where there were no significant differences (p>0.05) in the concentration of K. Soil pH did not display any significant differences (p>0.05) between communities and sites. The mean soil pH recorded in this study was 5.4 implying the soils of Njwaxa and Mbizana communities were acidic. It is evident that communal farmers are well aware of their rangeland condition, changes occurring in their rangelands, their causes and are capable of suggesting some solutions in controlling the declining condition of the rangelands. This study has shown the importance of engaging farmers’ inputs in range assessment since those are people bearing the consequences of rangeland degradation.
- Full Text:
- Date Issued: 2016
Bio-prospecting a Soil Metagenomic Library for Carbohydrate Active Esterases
- Authors: Shezi, Ntombifuthi
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4172 , http://hdl.handle.net/10962/d1021266
- Description: Lignocellulosic biomass is a promising renewable resource on earth. Plant biomass contains fermentable sugars and other moieties that can be converted to biofuels or other chemicals. Enzymatic hydrolysis of these biopolymers is significant in the liberation of sugars for fermentation into desired products. Owing to its complex structure, synergistic action of enzymes is required for its degradation. Enzymes that are involved in biomass degradation include cellulases, hemicellulases and the accessory enzymes acetyl xylan esterases and ferulic acid esterases. Ferulic acid esterases (FAEs, EC 3.1.1.73), represent a subclass of carboxylester hydrolases (EC 3.1.1.-) that catalyse the release of hydroxycinnamic acids (such as ferulic acid, p-coumaric, ferulic, sinapic and caffeic acid) that are generally found esterified to polysaccharides, such as arabinoxylans. Hydroxycinnamic acids have widespread potential applications due to their antimicrobial, photoprotectant and antioxidant properties, as well as their use as flavour precursors. Therefore, this interesting group of FAEs has a potentially wide variety of applications in agriculture, food and pharmaceutical industries. In the search for novel biocatalysts, metagenomics is considered as an alternative approach to conventional microbe screening, therefore, searching for novel biocatalysts from a soil metagenome that harbours a unique diversity of biocatalyst is significant. The aim of this study was to extract DNA from soil associated with cattle manure and construct a soil metagenomic library using a fosmid based plasmid vector and subsequently functionally screen for ferulic acid esterases using ethyl ferulate as a model substrate. A total of 59 recombinant fosmids conferring ferulic acid esterase phenotypes were identified (Hit rate 1:3122) and the two fosmids that consistently showed high FAE activities were selected for further study. Following nucleotide sequencing and translational analysis, two fae encoding open reading frames (FAE9 and FAE27) of approximately 274 and 322 aa, respectively, were identified. The amino acid sequence of the two ORFs contained a classical conserved esterase/lipase G-x-S-x-G sequence motif. The two genes (fae9 and fae27) were successfully expressed in Escherichia coli BL21 (DE3) and the purified enzymes exhibited respective temperature optima of 50 °C and 40 °C, and respective pH optima of 6.0 and 7.0. Further biochemical characterisation showed that FAE9 and FAE27 have high substrate specificity, following the fact that EFA is the preferred substrate for FAE9 (kcat/Km value of 128 s−1.mM-1) and also the preferred substrate for FAE27 (kcat/Km value of 137 s−1.mM-1). This work proves that soil is a valuable environmental source for novel esterase screening through functional based metagenomic approach. Therefore, this method may be used to screen for other valuable enzymes from environmental sources using inexpensive natural sources to encourage the screening of specific enzymes. Biochemistry of the two isolated enzymes makes these enzymes to be useful in industrial applications due to broad substrate activity that could replace the specialised enzymes to complete plant biomass degradation.
- Full Text:
- Date Issued: 2016
- Authors: Shezi, Ntombifuthi
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4172 , http://hdl.handle.net/10962/d1021266
- Description: Lignocellulosic biomass is a promising renewable resource on earth. Plant biomass contains fermentable sugars and other moieties that can be converted to biofuels or other chemicals. Enzymatic hydrolysis of these biopolymers is significant in the liberation of sugars for fermentation into desired products. Owing to its complex structure, synergistic action of enzymes is required for its degradation. Enzymes that are involved in biomass degradation include cellulases, hemicellulases and the accessory enzymes acetyl xylan esterases and ferulic acid esterases. Ferulic acid esterases (FAEs, EC 3.1.1.73), represent a subclass of carboxylester hydrolases (EC 3.1.1.-) that catalyse the release of hydroxycinnamic acids (such as ferulic acid, p-coumaric, ferulic, sinapic and caffeic acid) that are generally found esterified to polysaccharides, such as arabinoxylans. Hydroxycinnamic acids have widespread potential applications due to their antimicrobial, photoprotectant and antioxidant properties, as well as their use as flavour precursors. Therefore, this interesting group of FAEs has a potentially wide variety of applications in agriculture, food and pharmaceutical industries. In the search for novel biocatalysts, metagenomics is considered as an alternative approach to conventional microbe screening, therefore, searching for novel biocatalysts from a soil metagenome that harbours a unique diversity of biocatalyst is significant. The aim of this study was to extract DNA from soil associated with cattle manure and construct a soil metagenomic library using a fosmid based plasmid vector and subsequently functionally screen for ferulic acid esterases using ethyl ferulate as a model substrate. A total of 59 recombinant fosmids conferring ferulic acid esterase phenotypes were identified (Hit rate 1:3122) and the two fosmids that consistently showed high FAE activities were selected for further study. Following nucleotide sequencing and translational analysis, two fae encoding open reading frames (FAE9 and FAE27) of approximately 274 and 322 aa, respectively, were identified. The amino acid sequence of the two ORFs contained a classical conserved esterase/lipase G-x-S-x-G sequence motif. The two genes (fae9 and fae27) were successfully expressed in Escherichia coli BL21 (DE3) and the purified enzymes exhibited respective temperature optima of 50 °C and 40 °C, and respective pH optima of 6.0 and 7.0. Further biochemical characterisation showed that FAE9 and FAE27 have high substrate specificity, following the fact that EFA is the preferred substrate for FAE9 (kcat/Km value of 128 s−1.mM-1) and also the preferred substrate for FAE27 (kcat/Km value of 137 s−1.mM-1). This work proves that soil is a valuable environmental source for novel esterase screening through functional based metagenomic approach. Therefore, this method may be used to screen for other valuable enzymes from environmental sources using inexpensive natural sources to encourage the screening of specific enzymes. Biochemistry of the two isolated enzymes makes these enzymes to be useful in industrial applications due to broad substrate activity that could replace the specialised enzymes to complete plant biomass degradation.
- Full Text:
- Date Issued: 2016
Entomopathogenic fungi for control of soil-borne life stages of false codling moth, Thaumatotibia leucotreta (Meyrick) (1912) (Lepidoptera: Tortricidae)
- Authors: Coombes, Candice Anne
- Date: 2013
- Subjects: Tortricidae , Lepidoptera , Cryptophlebia leucotreta , Insect pests -- Biological control -- South Africa -- Eastern Cape , Tortricidae -- Biological control -- South Africa -- Eastern Cape , Citrus -- Diseases and pests -- Biological control -- South Africa -- Eastern Cape , Entomopathogenic fungi , Fungi as biological pest control agents , Biological pest control agents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5607 , http://hdl.handle.net/10962/d1002057 , Tortricidae , Lepidoptera , Cryptophlebia leucotreta , Insect pests -- Biological control -- South Africa -- Eastern Cape , Tortricidae -- Biological control -- South Africa -- Eastern Cape , Citrus -- Diseases and pests -- Biological control -- South Africa -- Eastern Cape , Entomopathogenic fungi , Fungi as biological pest control agents , Biological pest control agents
- Description: False codling moth (FCM), Thaumatotibia leucotreta is an extremely important pest of citrus in South Africa and with the shift away from the use of chemicals, alternate control options are needed. One avenue of control which has only recently been investigated against the soil-borne life stages of FCM is the use of entomopathogenic fungi (EPF). In 2009, 12 entomopathogenic fungal isolates collected from South African citrus orchards showed good control potential during laboratory conducted bioassays. The aim of this study was to further analyse the potential of these isolates through concentration-dose and exposure-time response bioassays. After initial re-screening, concentration-dose response and exposure-time response sandconidial bioassays, three isolates were identified as exhibiting the greatest control potential against FCM in soil, Metarhizium anisopliae var. anisopliae (G 11 3 L6 and FCM Ar 23 B3) and Beauveria bassiana (G Ar 17 B3). Percentage mycosis was found to be directly related to fungal concentration as well as the amount of time FCM 5th instar larvae were exposed to the fungal conidia. LC50 values for the three isolates were not greater than 1.92 x 10⁶ conidia.ml⁻ₑ and at the LC₅₀, FCM 5th instar larvae would need to be exposed to the fungus for a maximum of 13 days to ensure a high mortality level. These isolates along with two commercially available EPF products were subjected to field persistence trials whereby net bags filled with a mixture of autoclaved sand and formulated fungal product were buried in an Eastern Cape citrus orchard. The viability of each isolate was measured on a monthly basis for a period of six months. All isolates were capable of persisting in the soil for six months with the collected isolates persisting far better than the commercially used isolates. Two of the isolates, G 11 3 L6 and G Ar 17 B3, were subjected to small scale laboratory application trials. Two formulations were investigated at two concentrations. For each isolate, each formulation and each concentration, FCM 5th instar larvae were applied and allowed to burrow into the soil to pupate before fungal application or after fungal application. Contact between fungi and FCM host is essential as, in contrast to pre-larval treatments, percentage mortality in post-larval treatments was low for both formulations and both isolates. For isolate G Ar 17 B3, a conidial suspension applied as a spray at a concentration of 1 x 10⁷ conidia.ml⁻ₑ obtained the highest percentage mortality (80 %). For isolate G 11 3 L6 however, both formulations performed equally well at a high, 1 x10⁷ conidia.ml⁻ₑ concentration (conidial suspension: 60 %; granular: 65 %) The results obtained thus far are promising for the control of FCM in citrus, but if these EPFs are to successfully integrate into current FCM control practices more research, some of which is discussed, is essential
- Full Text:
- Date Issued: 2013
- Authors: Coombes, Candice Anne
- Date: 2013
- Subjects: Tortricidae , Lepidoptera , Cryptophlebia leucotreta , Insect pests -- Biological control -- South Africa -- Eastern Cape , Tortricidae -- Biological control -- South Africa -- Eastern Cape , Citrus -- Diseases and pests -- Biological control -- South Africa -- Eastern Cape , Entomopathogenic fungi , Fungi as biological pest control agents , Biological pest control agents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5607 , http://hdl.handle.net/10962/d1002057 , Tortricidae , Lepidoptera , Cryptophlebia leucotreta , Insect pests -- Biological control -- South Africa -- Eastern Cape , Tortricidae -- Biological control -- South Africa -- Eastern Cape , Citrus -- Diseases and pests -- Biological control -- South Africa -- Eastern Cape , Entomopathogenic fungi , Fungi as biological pest control agents , Biological pest control agents
- Description: False codling moth (FCM), Thaumatotibia leucotreta is an extremely important pest of citrus in South Africa and with the shift away from the use of chemicals, alternate control options are needed. One avenue of control which has only recently been investigated against the soil-borne life stages of FCM is the use of entomopathogenic fungi (EPF). In 2009, 12 entomopathogenic fungal isolates collected from South African citrus orchards showed good control potential during laboratory conducted bioassays. The aim of this study was to further analyse the potential of these isolates through concentration-dose and exposure-time response bioassays. After initial re-screening, concentration-dose response and exposure-time response sandconidial bioassays, three isolates were identified as exhibiting the greatest control potential against FCM in soil, Metarhizium anisopliae var. anisopliae (G 11 3 L6 and FCM Ar 23 B3) and Beauveria bassiana (G Ar 17 B3). Percentage mycosis was found to be directly related to fungal concentration as well as the amount of time FCM 5th instar larvae were exposed to the fungal conidia. LC50 values for the three isolates were not greater than 1.92 x 10⁶ conidia.ml⁻ₑ and at the LC₅₀, FCM 5th instar larvae would need to be exposed to the fungus for a maximum of 13 days to ensure a high mortality level. These isolates along with two commercially available EPF products were subjected to field persistence trials whereby net bags filled with a mixture of autoclaved sand and formulated fungal product were buried in an Eastern Cape citrus orchard. The viability of each isolate was measured on a monthly basis for a period of six months. All isolates were capable of persisting in the soil for six months with the collected isolates persisting far better than the commercially used isolates. Two of the isolates, G 11 3 L6 and G Ar 17 B3, were subjected to small scale laboratory application trials. Two formulations were investigated at two concentrations. For each isolate, each formulation and each concentration, FCM 5th instar larvae were applied and allowed to burrow into the soil to pupate before fungal application or after fungal application. Contact between fungi and FCM host is essential as, in contrast to pre-larval treatments, percentage mortality in post-larval treatments was low for both formulations and both isolates. For isolate G Ar 17 B3, a conidial suspension applied as a spray at a concentration of 1 x 10⁷ conidia.ml⁻ₑ obtained the highest percentage mortality (80 %). For isolate G 11 3 L6 however, both formulations performed equally well at a high, 1 x10⁷ conidia.ml⁻ₑ concentration (conidial suspension: 60 %; granular: 65 %) The results obtained thus far are promising for the control of FCM in citrus, but if these EPFs are to successfully integrate into current FCM control practices more research, some of which is discussed, is essential
- Full Text:
- Date Issued: 2013
Exploration for stratabound copper, lead and zinc deposits in the Damara-Katanga orogen, central-southern Africa
- Authors: Latorre, J J
- Date: 1992
- Subjects: Mining geology -- Research -- Africa , Copper ores -- Africa , Lead ores -- Africa , Zinc ores -- Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4946 , http://hdl.handle.net/10962/d1005558
- Description: The Damara-Katanga orogen in central-southern Africa represents an area of 1.73xl0⁶ sq. km. The region is considered one of the wealthiest metallogenic provinces in the world. Successful exploration for stratabound base-metal deposits has taken place at this particular area since the introduction of more organised methodology in the early 1920s. The genesis, location and distribution of the ore deposits are related to their tectonic settings. Geodynamic evolution of the orogen, which initially formed part of a complex Pan-African rift system, comprises the following stages rifting; downwarping, including spreading on the western portion; syn-orogeny and late-orogeny. Two major tectonic events in the history of the region have been identified: the Katangan (900-750 Ma) and the Damaran episodes (750-500 Ma). Timing of mineralisation of ore deposits has been related to the evolutionary stages of the orogen. Genetic models of the most productive deposits are briefly discussed in this dissertation. The sedimentological, geochemical, paleogeographic and structural features can be employed as geological guidelines for integrated exploration programmes. Discoveries of major deposits and prospects in the orogen are also summarised, focussing on the exploration methods employed. The cost-effective use of the exploration techniques includes the classical copper-lead-zinc soil sampling for residual soils such as those in the Copperbelt area. Airborne magnetics and electromagnetics and follow-up ground geophysics have proved successful in areas where the cover is transported in the search for shallow ore deposits such as the Matchless massive sulphides. Remote sensing, geochemical and geophysical techniques have been tried in covered areas of western Botswana. The lack of geological control makes this interpretation difficult. A detailed geological mapping and the use of geochemical and geophysical techniques has been used to delineate carbonate-hosted base-metal deposits at the Otavi Land. The more expensive traditional methods necessary for the delineation of orebodies, such as pitting, trenching and drilling, are also discussed. Using a sequential approach, a possible exploration strategy is suggested, outlining the cost-effective use of remote sensing, geochemical and geophysical techniques. Standardisation in basic geological information is required for future successful explorations in the Damara-Katanga orogen, as well as attractive mining policies. In the event of their implementation, exploration perspectives are promising, specifically in terms of ore potential.
- Full Text:
- Date Issued: 1992
- Authors: Latorre, J J
- Date: 1992
- Subjects: Mining geology -- Research -- Africa , Copper ores -- Africa , Lead ores -- Africa , Zinc ores -- Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4946 , http://hdl.handle.net/10962/d1005558
- Description: The Damara-Katanga orogen in central-southern Africa represents an area of 1.73xl0⁶ sq. km. The region is considered one of the wealthiest metallogenic provinces in the world. Successful exploration for stratabound base-metal deposits has taken place at this particular area since the introduction of more organised methodology in the early 1920s. The genesis, location and distribution of the ore deposits are related to their tectonic settings. Geodynamic evolution of the orogen, which initially formed part of a complex Pan-African rift system, comprises the following stages rifting; downwarping, including spreading on the western portion; syn-orogeny and late-orogeny. Two major tectonic events in the history of the region have been identified: the Katangan (900-750 Ma) and the Damaran episodes (750-500 Ma). Timing of mineralisation of ore deposits has been related to the evolutionary stages of the orogen. Genetic models of the most productive deposits are briefly discussed in this dissertation. The sedimentological, geochemical, paleogeographic and structural features can be employed as geological guidelines for integrated exploration programmes. Discoveries of major deposits and prospects in the orogen are also summarised, focussing on the exploration methods employed. The cost-effective use of the exploration techniques includes the classical copper-lead-zinc soil sampling for residual soils such as those in the Copperbelt area. Airborne magnetics and electromagnetics and follow-up ground geophysics have proved successful in areas where the cover is transported in the search for shallow ore deposits such as the Matchless massive sulphides. Remote sensing, geochemical and geophysical techniques have been tried in covered areas of western Botswana. The lack of geological control makes this interpretation difficult. A detailed geological mapping and the use of geochemical and geophysical techniques has been used to delineate carbonate-hosted base-metal deposits at the Otavi Land. The more expensive traditional methods necessary for the delineation of orebodies, such as pitting, trenching and drilling, are also discussed. Using a sequential approach, a possible exploration strategy is suggested, outlining the cost-effective use of remote sensing, geochemical and geophysical techniques. Standardisation in basic geological information is required for future successful explorations in the Damara-Katanga orogen, as well as attractive mining policies. In the event of their implementation, exploration perspectives are promising, specifically in terms of ore potential.
- Full Text:
- Date Issued: 1992
Identification of novel SNPSTRs by 454 sequencing in Nguni and Sotho-Tswana populations
- Authors: Laurence, Jo-Anne Elizabeth
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/55885 , vital:26752
- Description: DNA profiling is currently performed by analysis of the electropherogram that results following the amplification of a panel of Short Tandem Repeat (STR) loci. A need has arisen, however, for the development of a typing method that generates results which are compatible and comparable with existing databases, but that have a higher discrimination power by supplying sequence data as well as repeat-number data. Recent studies that explore these alternative typing methodologies have revealed the existence of a number of STR variants. There is, however, little information about the exact nature and prevalence of these sub-alleles. There have also been limited population studies of the genetic profiles of sub-Saharan African populations, despite the fact that evidence suggests that there is greater genetic structure and genetic diversity in these populations. In this study, a processing protocol for the generation of 454 sequencing-ready amplicons of vWA, D2S441, D3S1358, D13S317, D21S11 and D7S820 loci was developed. This protocol was applied to buccal swabs collected from 144 individuals of the Nguni and Sotho-Tswana population groups. A total of 145 485 reads were obtained from the sequencing of these amplicons, of which 97 400 and 48 085 reads were obtained for the Nguni and Sotho-Tswana populations respectively. The proportional representation for each locus ranged from 8-20%, and the allele calls and observed frequencies of these alleles suggested a high degree of relatedness between population groups. The sequencing results, furthermore, enabled the identification of a number of previously undescribed STR variants and SNPSTRs; with allele 13´ for D13S317 representing a SNP that may be predictive of Nguni-ancestry. The results also demonstrated the usefulness of next generation sequencing for increasing the number of discernible alleles for STR profiling.
- Full Text:
- Date Issued: 2015
- Authors: Laurence, Jo-Anne Elizabeth
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/55885 , vital:26752
- Description: DNA profiling is currently performed by analysis of the electropherogram that results following the amplification of a panel of Short Tandem Repeat (STR) loci. A need has arisen, however, for the development of a typing method that generates results which are compatible and comparable with existing databases, but that have a higher discrimination power by supplying sequence data as well as repeat-number data. Recent studies that explore these alternative typing methodologies have revealed the existence of a number of STR variants. There is, however, little information about the exact nature and prevalence of these sub-alleles. There have also been limited population studies of the genetic profiles of sub-Saharan African populations, despite the fact that evidence suggests that there is greater genetic structure and genetic diversity in these populations. In this study, a processing protocol for the generation of 454 sequencing-ready amplicons of vWA, D2S441, D3S1358, D13S317, D21S11 and D7S820 loci was developed. This protocol was applied to buccal swabs collected from 144 individuals of the Nguni and Sotho-Tswana population groups. A total of 145 485 reads were obtained from the sequencing of these amplicons, of which 97 400 and 48 085 reads were obtained for the Nguni and Sotho-Tswana populations respectively. The proportional representation for each locus ranged from 8-20%, and the allele calls and observed frequencies of these alleles suggested a high degree of relatedness between population groups. The sequencing results, furthermore, enabled the identification of a number of previously undescribed STR variants and SNPSTRs; with allele 13´ for D13S317 representing a SNP that may be predictive of Nguni-ancestry. The results also demonstrated the usefulness of next generation sequencing for increasing the number of discernible alleles for STR profiling.
- Full Text:
- Date Issued: 2015
Network-layer reservation TDM for ad-hoc 802.11 networks
- Authors: Duff, Kevin Craig
- Date: 2008
- Subjects: Computer networks -- Access control , Computers -- Access control , Computer networks -- Management , Time division multiple access , Ad hoc networks (Computer networks)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4574 , http://hdl.handle.net/10962/d1002773 , Computer networks -- Access control , Computers -- Access control , Computer networks -- Management , Time division multiple access , Ad hoc networks (Computer networks)
- Description: Ad-Hoc mesh networks offer great promise. Low-cost ad-hoc mesh networks can be built using popular IEEE 802.11 equipment, but such networks are unable to guarantee each node a fair share of bandwidth. Furthermore, hidden node problems cause collisions which can cripple the throughput of a network. This research proposes a novel mechanism which is able to overcome hidden node problems and provide fair bandwidth sharing among nodes on ad-hoc 802.11 networks, and can be implemented on existing network devices. The scheme uses TDM (time division multiplexing) with slot reservation. A distributed beacon packet latency measurement mechanism is used to achieve node synchronisation. The distributed nature of the mechanism makes it applicable to ad-hoc 802.11 networks, which can either grow or fragment dynamically.
- Full Text:
- Date Issued: 2008
- Authors: Duff, Kevin Craig
- Date: 2008
- Subjects: Computer networks -- Access control , Computers -- Access control , Computer networks -- Management , Time division multiple access , Ad hoc networks (Computer networks)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4574 , http://hdl.handle.net/10962/d1002773 , Computer networks -- Access control , Computers -- Access control , Computer networks -- Management , Time division multiple access , Ad hoc networks (Computer networks)
- Description: Ad-Hoc mesh networks offer great promise. Low-cost ad-hoc mesh networks can be built using popular IEEE 802.11 equipment, but such networks are unable to guarantee each node a fair share of bandwidth. Furthermore, hidden node problems cause collisions which can cripple the throughput of a network. This research proposes a novel mechanism which is able to overcome hidden node problems and provide fair bandwidth sharing among nodes on ad-hoc 802.11 networks, and can be implemented on existing network devices. The scheme uses TDM (time division multiplexing) with slot reservation. A distributed beacon packet latency measurement mechanism is used to achieve node synchronisation. The distributed nature of the mechanism makes it applicable to ad-hoc 802.11 networks, which can either grow or fragment dynamically.
- Full Text:
- Date Issued: 2008
Upwelling on the Southeast Madagascan shelf: frequency, extent, and driving mechanisms
- Authors: Collins, Matthew
- Date: 2020
- Subjects: Upwelling (Oceanography) -- Madagascar , Oceanography -- Research -- Madagascar Marine biology -- Indian Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/49060 , vital:41597
- Description: The southeast coast of Madagascar, namely the region surrounding the town of Fort Dauphin, is an area that regularly experiences upwelling events. Two unique high frequency data sets, UTR data, and wind data retrieved from a nearby airport, are the primary data sets used to investigate the nature of the upwelling, i.e. the area that experiences upwelling, how often it occurs, and its mechanisms. To complement the in-situ data, several different satellite data sources are used alongside the in-situ data to study this relatively remote region, i.e. SST, chlorophyll-a concentration, current, and wind data. The results refine upon previous literature on the topic. The upwelling covers an area of 1o latitude by 1.3o longitude, and occurs on average 14 times per annum. The mechanism driving the upwelling can be attributed to both wind and current, with wind the more dominant driver along the south coast, and current more dominant along the east coast. Separate to the main objective of the thesis is the importance of in-situ data when analysing small scale events such as upwelling events. While the in-situ wind data were found to be unreliable due to its location within a valley, the UTR data were of vital importance in identifying and studying the finer details of the upwelling events. The satellite SST data, by comparison, were lacking in their ability to investigate the upwelling events. The satellite derived wind data, however, did prove useful when analysing the wind as a driver of the upwelling.
- Full Text:
- Date Issued: 2020
- Authors: Collins, Matthew
- Date: 2020
- Subjects: Upwelling (Oceanography) -- Madagascar , Oceanography -- Research -- Madagascar Marine biology -- Indian Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/49060 , vital:41597
- Description: The southeast coast of Madagascar, namely the region surrounding the town of Fort Dauphin, is an area that regularly experiences upwelling events. Two unique high frequency data sets, UTR data, and wind data retrieved from a nearby airport, are the primary data sets used to investigate the nature of the upwelling, i.e. the area that experiences upwelling, how often it occurs, and its mechanisms. To complement the in-situ data, several different satellite data sources are used alongside the in-situ data to study this relatively remote region, i.e. SST, chlorophyll-a concentration, current, and wind data. The results refine upon previous literature on the topic. The upwelling covers an area of 1o latitude by 1.3o longitude, and occurs on average 14 times per annum. The mechanism driving the upwelling can be attributed to both wind and current, with wind the more dominant driver along the south coast, and current more dominant along the east coast. Separate to the main objective of the thesis is the importance of in-situ data when analysing small scale events such as upwelling events. While the in-situ wind data were found to be unreliable due to its location within a valley, the UTR data were of vital importance in identifying and studying the finer details of the upwelling events. The satellite SST data, by comparison, were lacking in their ability to investigate the upwelling events. The satellite derived wind data, however, did prove useful when analysing the wind as a driver of the upwelling.
- Full Text:
- Date Issued: 2020
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