A review of generalized linear models for count data with emphasis on current geospatial procedures
- Authors: Michell, Justin Walter
- Date: 2016
- Subjects: Spatial analysis (Statistics) , Bayesian statistical decision theory , Geospatial data , Malaria -- Botswana -- Statistics , Malaria -- Botswana -- Research -- Statistical methods
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:5582 , http://hdl.handle.net/10962/d1019989
- Description: Analytical problems caused by over-fitting, confounding and non-independence in the data is a major challenge for variable selection. As more variables are tested against a certain data set, there is a greater risk that some will explain the data merely by chance, but will fail to explain new data. The main aim of this study is to employ a systematic and practicable variable selection process for the spatial analysis and mapping of historical malaria risk in Botswana using data collected from the MARA (Mapping Malaria Risk in Africa) project and environmental and climatic datasets from various sources. Details of how a spatial database is compiled for a statistical analysis to proceed is provided. The automation of the entire process is also explored. The final bayesian spatial model derived from the non-spatial variable selection procedure using Markov Chain Monte Carlo simulation was fitted to the data. Winter temperature had the greatest effect of malaria prevalence in Botswana. Summer rainfall, maximum temperature of the warmest month, annual range of temperature, altitude and distance to closest water source were also significantly associated with malaria prevalence in the final spatial model after accounting for spatial correlation. Using this spatial model malaria prevalence at unobserved locations was predicted, producing a smooth risk map covering Botswana. The automation of both compiling the spatial database and the variable selection procedure proved challenging and could only be achieved in parts of the process. The non-spatial selection procedure proved practical and was able to identify stable explanatory variables and provide an objective means for selecting one variable over another, however ultimately it was not entirely successful due to the fact that a unique set of spatial variables could not be selected.
- Full Text:
- Date Issued: 2016
- Authors: Michell, Justin Walter
- Date: 2016
- Subjects: Spatial analysis (Statistics) , Bayesian statistical decision theory , Geospatial data , Malaria -- Botswana -- Statistics , Malaria -- Botswana -- Research -- Statistical methods
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:5582 , http://hdl.handle.net/10962/d1019989
- Description: Analytical problems caused by over-fitting, confounding and non-independence in the data is a major challenge for variable selection. As more variables are tested against a certain data set, there is a greater risk that some will explain the data merely by chance, but will fail to explain new data. The main aim of this study is to employ a systematic and practicable variable selection process for the spatial analysis and mapping of historical malaria risk in Botswana using data collected from the MARA (Mapping Malaria Risk in Africa) project and environmental and climatic datasets from various sources. Details of how a spatial database is compiled for a statistical analysis to proceed is provided. The automation of the entire process is also explored. The final bayesian spatial model derived from the non-spatial variable selection procedure using Markov Chain Monte Carlo simulation was fitted to the data. Winter temperature had the greatest effect of malaria prevalence in Botswana. Summer rainfall, maximum temperature of the warmest month, annual range of temperature, altitude and distance to closest water source were also significantly associated with malaria prevalence in the final spatial model after accounting for spatial correlation. Using this spatial model malaria prevalence at unobserved locations was predicted, producing a smooth risk map covering Botswana. The automation of both compiling the spatial database and the variable selection procedure proved challenging and could only be achieved in parts of the process. The non-spatial selection procedure proved practical and was able to identify stable explanatory variables and provide an objective means for selecting one variable over another, however ultimately it was not entirely successful due to the fact that a unique set of spatial variables could not be selected.
- Full Text:
- Date Issued: 2016
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
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
The caramel Venus and other stories
- Authors: Terblanche, Tania
- Date: 2016
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:6006 , http://hdl.handle.net/10962/1021214
- Description: My collection of stories illustrates the absurdity, the beauty and the pain of being human by depicting experience through fabulation. The intensity of existence comes to light in strange worlds that operate by rules of our inner mechanics, distorted so that only the colours and the shape of our hearts swim underneath. My fiction embodies these realities using the flatness of the fairy tale form while incorporating the humorous, the bizarre and the surreal. Some of the stories build dystopian worlds using the manifestation of the unfamiliar as a mirror of our psyche in an overpopulated and consumer-driven society. Others create contained worlds where the fantastical is fostered only by the narrator being drawn into an inner life. All the stories take us through inner landscapes with the humans, animals and objects around us that can pulse with so much meaning and then none at all.
- Full Text:
- Date Issued: 2016
- Authors: Terblanche, Tania
- Date: 2016
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:6006 , http://hdl.handle.net/10962/1021214
- Description: My collection of stories illustrates the absurdity, the beauty and the pain of being human by depicting experience through fabulation. The intensity of existence comes to light in strange worlds that operate by rules of our inner mechanics, distorted so that only the colours and the shape of our hearts swim underneath. My fiction embodies these realities using the flatness of the fairy tale form while incorporating the humorous, the bizarre and the surreal. Some of the stories build dystopian worlds using the manifestation of the unfamiliar as a mirror of our psyche in an overpopulated and consumer-driven society. Others create contained worlds where the fantastical is fostered only by the narrator being drawn into an inner life. All the stories take us through inner landscapes with the humans, animals and objects around us that can pulse with so much meaning and then none at all.
- Full Text:
- Date Issued: 2016
The role of South Africa as a hegemonic' power in the maintenance of peace and stability in the SADC region
- Authors: Sibanda, Nkosiyaphi
- Date: 2016
- Subjects: Southern African Development Community Peace-building -- South Africa Conflict management -- South Africa
- Language: English
- Type: Thesis , Masters , MSoc
- Identifier: http://hdl.handle.net/10353/6491 , vital:29824
- Description: This study investigates South Africa’s role as a hegemonic power in maintaining peace and stability in the SADC region. Using qualitative and secondary data supplemented with primary data, the study examines not only South Africa’s hegemonic role in the SADC region but also the challenges and critiques of South Africa’s hegemonic role in the region. The study implores the hegemonic stability theory and explores the features that qualify South Africa to be a regional hegemonic power. These include South Africa’s economic power, military power and strategic location. This study reveals that South Africa’s role in maintaining peace and stability in the region is informed by its foreign policy and its pursuit of national interest and protection of its borders. The study also found out that the motive behind South Africa being active in peacekeeping missions is that it avoids being surrounded by failed states which might have spillover effects into its territorial boundaries. The study notes that there are numerous shortcomings which taint South Africa’s hegemonic status. They include violent protests, xenophobia, racism, crime and corruption. The study recommends that South Africa needs to be proactive in solving the challenges within its domestic terrain as these shortcomings taint its hegemonic status.
- Full Text:
- Date Issued: 2016
- Authors: Sibanda, Nkosiyaphi
- Date: 2016
- Subjects: Southern African Development Community Peace-building -- South Africa Conflict management -- South Africa
- Language: English
- Type: Thesis , Masters , MSoc
- Identifier: http://hdl.handle.net/10353/6491 , vital:29824
- Description: This study investigates South Africa’s role as a hegemonic power in maintaining peace and stability in the SADC region. Using qualitative and secondary data supplemented with primary data, the study examines not only South Africa’s hegemonic role in the SADC region but also the challenges and critiques of South Africa’s hegemonic role in the region. The study implores the hegemonic stability theory and explores the features that qualify South Africa to be a regional hegemonic power. These include South Africa’s economic power, military power and strategic location. This study reveals that South Africa’s role in maintaining peace and stability in the region is informed by its foreign policy and its pursuit of national interest and protection of its borders. The study also found out that the motive behind South Africa being active in peacekeeping missions is that it avoids being surrounded by failed states which might have spillover effects into its territorial boundaries. The study notes that there are numerous shortcomings which taint South Africa’s hegemonic status. They include violent protests, xenophobia, racism, crime and corruption. The study recommends that South Africa needs to be proactive in solving the challenges within its domestic terrain as these shortcomings taint its hegemonic status.
- Full Text:
- Date Issued: 2016
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