A contribution to TEC modelling over Southern Africa using GPS data
- Authors: Habarulema, John Bosco
- Date: 2010
- Subjects: Electrons -- Mathematical models Radio wave propagation Global positioning system -- Measurement Ionospheric radio wave propagation Atmospheric physics -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5456 , http://hdl.handle.net/10962/d1005241
- Description: Modelling ionospheric total electron content (TEC) is an important area of interest for radio wave propagation, geodesy, surveying, the understanding of space weather dynamics and error correction in relation to Global Navigation Satellite Systems (GNNS) applications. With the utilisation of improved ionosonde technology coupled with the use of GNSS, the response of technological systems due to changes in the ionosphere during both quiet and disturbed conditions can be historically inferred. TEC values are usually derived from GNSS measurements using mathematically intensive algorithms. However, the techniques used to estimate these TEC values depend heavily on the availability of near-real time GNSS data, and therefore, are sometimes unable to generate complete datasets. This thesis investigated possibilities for the modelling of TEC values derived from the South African Global Positioning System (GPS)receiver network using linear regression methods and artificial neural networks (NNs). GPS TEC values were derived using the Adjusted Spherical Harmonic Analysis (ASHA) algorithm. Considering TEC and the factors that influence its variability as “dependent and independent variables” respectively, the capabilities of linear regression methods and NNs for TEC modelling were first investigated using a small dataset from two GPS receiver stations. NN and regression models were separately developed and used to reproduce TEC fluctuations at different stations not included in the models’ development. For this purpose, TEC was modelled as a function of diurnal variation, seasonal variation, solar and magnetic activities. Comparative analysis showed that NN models provide predictions of GPS TEC that were an improvement on those predicted by the regression models developed. A separate study to empirically investigate the effects of solar wind on GPS TEC was carried out. Quantitative results indicated that solar wind does not have a significant influence on TEC variability. The final TEC simulation model developed makes use of the NN technique to find the relationship between historical TEC data variations and factors that are known to influence TEC variability (such as solar and magnetic activities, diurnal and seasonal variations and the geographical locations of the respective GPS stations) for the purposes of regional TEC modelling and mapping. The NN technique in conjunction with interpolation and extrapolation methods makes it possible to construct ionospheric TEC maps and to analyse the spatial and temporal TEC behaviour over Southern Africa. For independent validation, modelled TEC values were compared to ionosonde TEC and the International Reference Ionosphere (IRI) generated TEC values during both quiet and disturbed conditions. This thesis provides a comprehensive guide on the development of TEC models for predicting ionospheric variability over the South African region, and forms a significant contribution to ionospheric modelling efforts in Africa.
- Full Text:
- Date Issued: 2010
- Authors: Habarulema, John Bosco
- Date: 2010
- Subjects: Electrons -- Mathematical models Radio wave propagation Global positioning system -- Measurement Ionospheric radio wave propagation Atmospheric physics -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5456 , http://hdl.handle.net/10962/d1005241
- Description: Modelling ionospheric total electron content (TEC) is an important area of interest for radio wave propagation, geodesy, surveying, the understanding of space weather dynamics and error correction in relation to Global Navigation Satellite Systems (GNNS) applications. With the utilisation of improved ionosonde technology coupled with the use of GNSS, the response of technological systems due to changes in the ionosphere during both quiet and disturbed conditions can be historically inferred. TEC values are usually derived from GNSS measurements using mathematically intensive algorithms. However, the techniques used to estimate these TEC values depend heavily on the availability of near-real time GNSS data, and therefore, are sometimes unable to generate complete datasets. This thesis investigated possibilities for the modelling of TEC values derived from the South African Global Positioning System (GPS)receiver network using linear regression methods and artificial neural networks (NNs). GPS TEC values were derived using the Adjusted Spherical Harmonic Analysis (ASHA) algorithm. Considering TEC and the factors that influence its variability as “dependent and independent variables” respectively, the capabilities of linear regression methods and NNs for TEC modelling were first investigated using a small dataset from two GPS receiver stations. NN and regression models were separately developed and used to reproduce TEC fluctuations at different stations not included in the models’ development. For this purpose, TEC was modelled as a function of diurnal variation, seasonal variation, solar and magnetic activities. Comparative analysis showed that NN models provide predictions of GPS TEC that were an improvement on those predicted by the regression models developed. A separate study to empirically investigate the effects of solar wind on GPS TEC was carried out. Quantitative results indicated that solar wind does not have a significant influence on TEC variability. The final TEC simulation model developed makes use of the NN technique to find the relationship between historical TEC data variations and factors that are known to influence TEC variability (such as solar and magnetic activities, diurnal and seasonal variations and the geographical locations of the respective GPS stations) for the purposes of regional TEC modelling and mapping. The NN technique in conjunction with interpolation and extrapolation methods makes it possible to construct ionospheric TEC maps and to analyse the spatial and temporal TEC behaviour over Southern Africa. For independent validation, modelled TEC values were compared to ionosonde TEC and the International Reference Ionosphere (IRI) generated TEC values during both quiet and disturbed conditions. This thesis provides a comprehensive guide on the development of TEC models for predicting ionospheric variability over the South African region, and forms a significant contribution to ionospheric modelling efforts in Africa.
- Full Text:
- Date Issued: 2010
Psigobiografiese persoonlikheidsbeskrywing van Generaal Christiaan de Wet
- Authors: Henning, Riana
- Date: 2010
- Subjects: De Wet, Christiaan Rudolf, 1854-1922 Psychology -- Biographical methods Psychoanalysis Big Five model Politicians -- Psychology South Africa -- Politics and government -- 1836-1909 South Africa -- Politics and government -- 1909-1948
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2990 , http://hdl.handle.net/10962/d1002499
- Description: Hierdie is 'n psigobiografiese studie van Generaal Christiaan Rudolph de Wet. 'n Psigobiografiese studie is die bestudering van 'n persoon se volledige lewe met die doel om die persoon beter te verstaan. Psigobiografiese navorsing maak gebruik van psigologiese teorieë wat aangewend word om die biografiese data van 'n persoon se lewe te beskryf en moontlik ook te verklaar. Die individu wat bestudeer word, is gewoonlik 'n bekende, invloedryke, navolgenswaardige, interessante of modelfiguur. Daar is tans 'n oplewing in die veld van psigobiografiese studies, maar daar word nog steeds nie genoeg in die akademiese veld gedoen om psigobiografiese studies te bevorder nie. De Wet (1854-1922) is vir hierdie studie gekies omdat hy 'n interessante, dog komplekse figuur was. Hy het veral tydens die Anglo-Boereoorlog in 1899-1902 bekendheid verwerf. As 45-jarige man het De Wet in die Anglo-Boereoorlog geveg en vinnig opgang as 'n militêre leier gemaak. Sy vindingryke ontsnappingspogings het die Britse magte hoofbrekens besorg. Wat De Wet verder uniek maak, is dat hy met net drie maande skoolopleiding in die parlement gedien het, as president verkies is, die hoogste gesag in die Verdedigingsmag gehad het en 'n boek oor sy oorlogsherinneringe geskryf het. Alhoewel daar akademiese werke oor De Wet bestaan, is daar tot op hede nog geen psigobiografiese studie oor hom gedoen nie. Die doel van die studie was om die mens agter die legende na vore te bring. Daar is ook gepoog om moontlike antwoorde en verklarings op onbeantwoorde vrae te gee. Die studie het van beide kwalitatiewe en kwantitatiewe data gebruik gemaak en kan as 'n psigobiografiese gevalstudie beskryf word. Die Vyf-faktor model van Costa en McCrae (1992) is op die biografiese data van De Wet toegepas om sodoende sy persoonlikheidseienskappe te beskryf. Die bevindinge het interessante persoonlikheidseienskappe van De Wet deur middel van die Vyf-faktor model aan die lig gebring. Volgens die kwalitatiewe navorsingsbevindinge was De Wet 'n vyandige, aksie-gedrewe, bevoegde, prestasie-strewende, selfgedissiplineerde, warm, openhartige, saggeaarde en beskeie persoon. Die kwalitatiewe en kwantitatiewe data-ontledings het uiteenlopende persoonlikheidskenmerke by De Wet geïdentifiseer. Die grootste verskille het by die fasette warmte, openhartigheid en altruïsme voorgekom. Die waarde van die studie is dat 'n wetenskaplike persoonlikheidsontleding van De Wet gedoen is. Dit is ook die eerste studie waar 'n teoretiese model op De Wet se persoonlikheid toegepas is. Alhoewel die studie sekere tekortkominge toon, beklemtoon dit terselfdertyd die wenslikheid daarvan om alternatiewe modelle te gebruik tydens die ontleding van persoonlikheidskenmerke. Die studie dui ook op die behoefte aan verdere navorsing, byvoorbeeld soortgelyke ontledings en vergelykings van die persoonlikhede van ander militêre bevelvoerders (De la Rey, Smuts, Beyers, Hertzog).
- Full Text:
- Date Issued: 2010
- Authors: Henning, Riana
- Date: 2010
- Subjects: De Wet, Christiaan Rudolf, 1854-1922 Psychology -- Biographical methods Psychoanalysis Big Five model Politicians -- Psychology South Africa -- Politics and government -- 1836-1909 South Africa -- Politics and government -- 1909-1948
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2990 , http://hdl.handle.net/10962/d1002499
- Description: Hierdie is 'n psigobiografiese studie van Generaal Christiaan Rudolph de Wet. 'n Psigobiografiese studie is die bestudering van 'n persoon se volledige lewe met die doel om die persoon beter te verstaan. Psigobiografiese navorsing maak gebruik van psigologiese teorieë wat aangewend word om die biografiese data van 'n persoon se lewe te beskryf en moontlik ook te verklaar. Die individu wat bestudeer word, is gewoonlik 'n bekende, invloedryke, navolgenswaardige, interessante of modelfiguur. Daar is tans 'n oplewing in die veld van psigobiografiese studies, maar daar word nog steeds nie genoeg in die akademiese veld gedoen om psigobiografiese studies te bevorder nie. De Wet (1854-1922) is vir hierdie studie gekies omdat hy 'n interessante, dog komplekse figuur was. Hy het veral tydens die Anglo-Boereoorlog in 1899-1902 bekendheid verwerf. As 45-jarige man het De Wet in die Anglo-Boereoorlog geveg en vinnig opgang as 'n militêre leier gemaak. Sy vindingryke ontsnappingspogings het die Britse magte hoofbrekens besorg. Wat De Wet verder uniek maak, is dat hy met net drie maande skoolopleiding in die parlement gedien het, as president verkies is, die hoogste gesag in die Verdedigingsmag gehad het en 'n boek oor sy oorlogsherinneringe geskryf het. Alhoewel daar akademiese werke oor De Wet bestaan, is daar tot op hede nog geen psigobiografiese studie oor hom gedoen nie. Die doel van die studie was om die mens agter die legende na vore te bring. Daar is ook gepoog om moontlike antwoorde en verklarings op onbeantwoorde vrae te gee. Die studie het van beide kwalitatiewe en kwantitatiewe data gebruik gemaak en kan as 'n psigobiografiese gevalstudie beskryf word. Die Vyf-faktor model van Costa en McCrae (1992) is op die biografiese data van De Wet toegepas om sodoende sy persoonlikheidseienskappe te beskryf. Die bevindinge het interessante persoonlikheidseienskappe van De Wet deur middel van die Vyf-faktor model aan die lig gebring. Volgens die kwalitatiewe navorsingsbevindinge was De Wet 'n vyandige, aksie-gedrewe, bevoegde, prestasie-strewende, selfgedissiplineerde, warm, openhartige, saggeaarde en beskeie persoon. Die kwalitatiewe en kwantitatiewe data-ontledings het uiteenlopende persoonlikheidskenmerke by De Wet geïdentifiseer. Die grootste verskille het by die fasette warmte, openhartigheid en altruïsme voorgekom. Die waarde van die studie is dat 'n wetenskaplike persoonlikheidsontleding van De Wet gedoen is. Dit is ook die eerste studie waar 'n teoretiese model op De Wet se persoonlikheid toegepas is. Alhoewel die studie sekere tekortkominge toon, beklemtoon dit terselfdertyd die wenslikheid daarvan om alternatiewe modelle te gebruik tydens die ontleding van persoonlikheidskenmerke. Die studie dui ook op die behoefte aan verdere navorsing, byvoorbeeld soortgelyke ontledings en vergelykings van die persoonlikhede van ander militêre bevelvoerders (De la Rey, Smuts, Beyers, Hertzog).
- Full Text:
- Date Issued: 2010
Induced plant responses of different Lantana camara L. (Verbenaceae) varieties to herbivory by Falconia intermedia (distant) (Hemiptera: Miridae)
- Heshula, Unathi-Nkosi Lelethu Peter
- Authors: Heshula, Unathi-Nkosi Lelethu Peter
- Date: 2010
- Subjects: Lantana camara -- South Africa -- Eastern Cape , Lantana camara -- Biological control -- South Africa -- Eastern Cape , Biological pest control agents -- South Africa -- Eastern Cape , Weeds -- Biological control -- South Africa -- Eastern Cape , Invasive plants -- Biological control -- South Africa -- Eastern Cape , Hemiptera -- South Africa -- Eastern Cape , Miridae -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5911 , http://hdl.handle.net/10962/d1015368
- Description: A highly variable invasive shrub, Lantana camara L. (Verbenaceae), has been notoriously difficult to control thus far despite a well established biological control programme in South Africa. A promising leaf-feeding biological control agent, Falconia intermedia (Distant) (Hemiptera: Miridae), released to control this invasive plant eventually crashed at three out of five sites in the Eastern Cape Province. In the Mpumalanga Province, after initially colonising and building up high numbers on the L. camara stands the agent populations crashed. Several reasons for these population crashes have been suggested, but induced plant defences have not been investigated. Although plants face the challenge of herbivory by various organisms while remaining immobile, some plants may possess the ability to induce physical and/or chemical defensive responses following feeding and thus prevent further plant tissue damage and loss. Laboratory trials were conducted to determine the existence, nature and effect of physical and chemical feeding-induced responses of L. camara on the performance of the leaf-feeding biological control agent, F. intermedia. Lantana camara plants used in the study were obtained from five localities in the Eastern Cape Province, South Africa, while the insect culture was established from field populations. Plants from all varieties on which F. intermedia was released significantly increased the toughness of their leaves compared to control treatment plants. In addition, plants from three localities: Lyndhurst Farm, East London and Port Alfred, significantly increased trichome density after prolonged feeding by F. intermedia. On the three varieties showing increases in these two factors (i.e. leaf toughness and trichome density), oviposition, survival and feeding damage by the mirid agent was significantly lower on previously damaged plants. A significant negative correlation between trichome density and population numbers was found (R²= 0.52, p < 0.0003), suggesting that an increase in trichome density strongly contributes to a reduction in F. intermedia's growth. The growth and reproduction of the resistant plants was not significantly impacted by F. intermedia feeding. The defensive responses were found to be plant systemic and rapidly induced as they were elicited and expressed throughout the plant in both damaged and undamaged leaves within five weeks after insect release. Leaf toughness and trichome density were not significantly increased after feeding on plants from Whitney Farm and Heather Glen Farm. On the contrary, mirid individuals performed significantly better on plants from Whitney Farm and Heather Glen Farm than on plants of other varieties, indicating their susceptibility and suitability to the agent and the lack of induced resistance against the agent. Plants from all localities besides East London showed some level of tolerance and overcompensated for feeding damage by increasing plant growth and reproductive factors on plants fed upon. This was however only significant in two variables of the more susceptible localities, Whitney Farm and Heather Glen Farm. This increase in plant fitness did however indicate an induced defence response by these plants to feeding, a response designed to lessen the effects of agent feeding. Headspace volatile analysis was used to investigate any volatile chemical responses by L. camara due to F. intermedia feeding at two of the five localities chosen: East London and Whitney Farm. There was no significant difference in headspace volatiles emitted by leaves of plants from the East London insect infested and control treatment plants. On the Whitney Farm damaged plants however there was a 2.5 fold increase in the emission intensity of one of the three main compounds, later identified as Beta-caryophyllene. Three major chemical constituents which were found to be common to leaf volatiles of the two varieties were identified through gas chromatography-mass spectrometry (GC-MS) from the damaged and undamaged leaves of these two varieties. The methods used in collecting leaf volatiles were shown to be significant in the strength of chromatogram peaks. Using general authentication methods and purified standards, one of these was identified as the sesquiterpene, Beta-caryophyllene (C₁₅H₂₄). This compound is one of the major constituents found in isolations of L. camara varieties worldwide. This is the first such work done on a variety of L. camara in South Africa, and hopefully the beginning of more in-depth studies of the volatile organic chemicals from the numerous naturalised varieties of L. camara. It is suggested that the sum of these responses may play a role bigger than is currently understood in this plant-insect relationship. It is also argued that feeding induced plant defences may play an important role in attempts to control alien plants using insect agents.
- Full Text:
- Date Issued: 2010
- Authors: Heshula, Unathi-Nkosi Lelethu Peter
- Date: 2010
- Subjects: Lantana camara -- South Africa -- Eastern Cape , Lantana camara -- Biological control -- South Africa -- Eastern Cape , Biological pest control agents -- South Africa -- Eastern Cape , Weeds -- Biological control -- South Africa -- Eastern Cape , Invasive plants -- Biological control -- South Africa -- Eastern Cape , Hemiptera -- South Africa -- Eastern Cape , Miridae -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5911 , http://hdl.handle.net/10962/d1015368
- Description: A highly variable invasive shrub, Lantana camara L. (Verbenaceae), has been notoriously difficult to control thus far despite a well established biological control programme in South Africa. A promising leaf-feeding biological control agent, Falconia intermedia (Distant) (Hemiptera: Miridae), released to control this invasive plant eventually crashed at three out of five sites in the Eastern Cape Province. In the Mpumalanga Province, after initially colonising and building up high numbers on the L. camara stands the agent populations crashed. Several reasons for these population crashes have been suggested, but induced plant defences have not been investigated. Although plants face the challenge of herbivory by various organisms while remaining immobile, some plants may possess the ability to induce physical and/or chemical defensive responses following feeding and thus prevent further plant tissue damage and loss. Laboratory trials were conducted to determine the existence, nature and effect of physical and chemical feeding-induced responses of L. camara on the performance of the leaf-feeding biological control agent, F. intermedia. Lantana camara plants used in the study were obtained from five localities in the Eastern Cape Province, South Africa, while the insect culture was established from field populations. Plants from all varieties on which F. intermedia was released significantly increased the toughness of their leaves compared to control treatment plants. In addition, plants from three localities: Lyndhurst Farm, East London and Port Alfred, significantly increased trichome density after prolonged feeding by F. intermedia. On the three varieties showing increases in these two factors (i.e. leaf toughness and trichome density), oviposition, survival and feeding damage by the mirid agent was significantly lower on previously damaged plants. A significant negative correlation between trichome density and population numbers was found (R²= 0.52, p < 0.0003), suggesting that an increase in trichome density strongly contributes to a reduction in F. intermedia's growth. The growth and reproduction of the resistant plants was not significantly impacted by F. intermedia feeding. The defensive responses were found to be plant systemic and rapidly induced as they were elicited and expressed throughout the plant in both damaged and undamaged leaves within five weeks after insect release. Leaf toughness and trichome density were not significantly increased after feeding on plants from Whitney Farm and Heather Glen Farm. On the contrary, mirid individuals performed significantly better on plants from Whitney Farm and Heather Glen Farm than on plants of other varieties, indicating their susceptibility and suitability to the agent and the lack of induced resistance against the agent. Plants from all localities besides East London showed some level of tolerance and overcompensated for feeding damage by increasing plant growth and reproductive factors on plants fed upon. This was however only significant in two variables of the more susceptible localities, Whitney Farm and Heather Glen Farm. This increase in plant fitness did however indicate an induced defence response by these plants to feeding, a response designed to lessen the effects of agent feeding. Headspace volatile analysis was used to investigate any volatile chemical responses by L. camara due to F. intermedia feeding at two of the five localities chosen: East London and Whitney Farm. There was no significant difference in headspace volatiles emitted by leaves of plants from the East London insect infested and control treatment plants. On the Whitney Farm damaged plants however there was a 2.5 fold increase in the emission intensity of one of the three main compounds, later identified as Beta-caryophyllene. Three major chemical constituents which were found to be common to leaf volatiles of the two varieties were identified through gas chromatography-mass spectrometry (GC-MS) from the damaged and undamaged leaves of these two varieties. The methods used in collecting leaf volatiles were shown to be significant in the strength of chromatogram peaks. Using general authentication methods and purified standards, one of these was identified as the sesquiterpene, Beta-caryophyllene (C₁₅H₂₄). This compound is one of the major constituents found in isolations of L. camara varieties worldwide. This is the first such work done on a variety of L. camara in South Africa, and hopefully the beginning of more in-depth studies of the volatile organic chemicals from the numerous naturalised varieties of L. camara. It is suggested that the sum of these responses may play a role bigger than is currently understood in this plant-insect relationship. It is also argued that feeding induced plant defences may play an important role in attempts to control alien plants using insect agents.
- Full Text:
- Date Issued: 2010
Aerial optical fibres in telecommunication systems : SOP and PMD monitoring, and tolerance of modulation formats
- Authors: Ireeta, Winston Tumps
- Date: 2010
- Subjects: Optical communications , Fiber optics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10542 , http://hdl.handle.net/10948/1478 , http://hdl.handle.net/10948/d1012894 , Optical communications , Fiber optics
- Description: The topic of this thesis is aerial optical fibres in telecommunication systems: state of polarization (SOP) and polarization mode dispersion (PMD) monitoring and tolerance of modulation formats. Errors in optical fibre telecommunication systems are introduced when these polarization effects (SOP and PMD) change. These changes are so intense especially in aerial optical fibres. Part of the backbone of South Africa’s national grid includes long distances of aerial optical fibre between transmission exchange stations. The work in this thesis can be divided into three parts which all deal with the major aspects of PMD in deployed aerial optical fibres: characterization, environmental effects plus other perturbations, and tolerance of different modulation formats. In our work, SOP and PMD field measurements revealed that they both fluctuate more rapidly in deployed aerial optical fibres especially on windy and hot days. The SOP and PMD changes in the aerial optical fibres showed a significant correlation with these environmental parameters. SOP and PMD are stochastic in nature due to changes in the properties of the optical fibres and its positions because of both intrinsic and extrinsic perturbations. In our work, with only 184 PMD values measured and obtained by use of the FTB-5700 single-ended dispersion analyzer, the predicted theoretical Gaussian fit was obtained with a mean of 0.47 ps and standard deviation of 0.08 ps. This small standard deviation was justification for its robustness and accuracy. The statistical distributions for first-order polarization mode dispersion (FO-PMD) and second-order polarization mode dispersion (SO-PMD) for the first time were experimentally confirmed when measured using the FTB-5700 single-ended dispersion analyzer instrument for deployed aerial optical fibres. We were also able to determine the time scale over which to compensate FO-PMD in deployed aerial fibres using the directional time drift autocorrelation function method. It is slightly higher than 390 s for SOP measurements made on a particular windy and hot day. This is due to the fact that the changes of the PMD vector are known to be slower than the SOP changes. vi We also investigated the theoretical statistical distribution that corresponds to output SOP variations. The SOP variations can either be with wavelength (for buried fibre) or with time (for aerial fibre). Our results showed that the statistics of the relative SOP changes approached the distribution proposed by Foschini et al. (2000). Advanced optical modulation formats have become a key ingredient in the design of modern state-of-the-art wavelength-division-multiplexed (WDM) optical transmission systems. In our work, we investigated which of these advanced modulation formats is best suited for the South African network especially on systems that have links of aerial optical fibres. Keywords: aerial optical fibre, polarization mode dispersion (PMD), principal states of polarization (PSP), state of polarization (SOP), first-order PMD, second-order PMD.
- Full Text:
- Date Issued: 2010
- Authors: Ireeta, Winston Tumps
- Date: 2010
- Subjects: Optical communications , Fiber optics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10542 , http://hdl.handle.net/10948/1478 , http://hdl.handle.net/10948/d1012894 , Optical communications , Fiber optics
- Description: The topic of this thesis is aerial optical fibres in telecommunication systems: state of polarization (SOP) and polarization mode dispersion (PMD) monitoring and tolerance of modulation formats. Errors in optical fibre telecommunication systems are introduced when these polarization effects (SOP and PMD) change. These changes are so intense especially in aerial optical fibres. Part of the backbone of South Africa’s national grid includes long distances of aerial optical fibre between transmission exchange stations. The work in this thesis can be divided into three parts which all deal with the major aspects of PMD in deployed aerial optical fibres: characterization, environmental effects plus other perturbations, and tolerance of different modulation formats. In our work, SOP and PMD field measurements revealed that they both fluctuate more rapidly in deployed aerial optical fibres especially on windy and hot days. The SOP and PMD changes in the aerial optical fibres showed a significant correlation with these environmental parameters. SOP and PMD are stochastic in nature due to changes in the properties of the optical fibres and its positions because of both intrinsic and extrinsic perturbations. In our work, with only 184 PMD values measured and obtained by use of the FTB-5700 single-ended dispersion analyzer, the predicted theoretical Gaussian fit was obtained with a mean of 0.47 ps and standard deviation of 0.08 ps. This small standard deviation was justification for its robustness and accuracy. The statistical distributions for first-order polarization mode dispersion (FO-PMD) and second-order polarization mode dispersion (SO-PMD) for the first time were experimentally confirmed when measured using the FTB-5700 single-ended dispersion analyzer instrument for deployed aerial optical fibres. We were also able to determine the time scale over which to compensate FO-PMD in deployed aerial fibres using the directional time drift autocorrelation function method. It is slightly higher than 390 s for SOP measurements made on a particular windy and hot day. This is due to the fact that the changes of the PMD vector are known to be slower than the SOP changes. vi We also investigated the theoretical statistical distribution that corresponds to output SOP variations. The SOP variations can either be with wavelength (for buried fibre) or with time (for aerial fibre). Our results showed that the statistics of the relative SOP changes approached the distribution proposed by Foschini et al. (2000). Advanced optical modulation formats have become a key ingredient in the design of modern state-of-the-art wavelength-division-multiplexed (WDM) optical transmission systems. In our work, we investigated which of these advanced modulation formats is best suited for the South African network especially on systems that have links of aerial optical fibres. Keywords: aerial optical fibre, polarization mode dispersion (PMD), principal states of polarization (PSP), state of polarization (SOP), first-order PMD, second-order PMD.
- Full Text:
- Date Issued: 2010
A critical analysis of discourses constructing portfolio assessment practices in three Eastern Cape schools
- Authors: Jones, Barbara Ellen
- Date: 2010
- Subjects: Discourse analysis -- South Africa -- Eastern Cape -- Case studies Competency-based education -- South Africa -- Eastern Cape -- Case studies Educational tests and measurements -- South Africa -- Eastern Cape -- Case studies Education -- Evaluation -- South Africa -- Eastern Cape -- Case studies Curriculum evaluation -- South Africa -- Eastern Cape -- Case studies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1468 , http://hdl.handle.net/10962/d1003349
- Description: In 1998, South Africa introduced outcomes-based education to affect the shifts in pedagogy considered necessary following the move to democracy in 1994. Across the globe, the use of the portfolio to assess learners is increasingly being promoted as a form of progressive pedagogy. Hence, its adoption by the country as a new form of assessment practice was warranted. However, how the portfolio is constructed and perceived by educators within the classroom can become problematic in practice. This was apparent in the South African context and justifies research into how the portfolio is constructed as an assessment method in educational policy and by educators in the classrooms. The Curriculum Guide Directive text and the transcripts of twenty-one interviews carried out in three Eastern Cape schools served as the source of data for this study. Discourses make up a powerful framework of spoken, written and symbolic texts of institutional bureaucracies. Within these institutions human subjects are defined and constructed. Therefore, discourse construction acts as institutional forms of knowledge which can exude power over the individual if not made transparent. I used critical discourse analysis to uncover the discourses that were embedded within the Curriculum Guide Directive and to identify the discourses entrenched within the educators’ perceptions of the portfolio. The discourses in the Curriculum Guide Directive suggest the construction of the portfolio as a method of surveillance to track whether the educators are preparing learners for the school leaving examination and instructing the educators to provide evidence in the form of a portfolio. Analysis of the transcripts of the twenty one interviews with educators from three schools in the Eastern Cape indicated that the portfolio was not seen as a form of assessment by the educators, but as a form of discipline put in place by the Department of Education to ensure that they are preparing the learners for the school leaving examination and are able to produce proof of this preparation in the form of a portfolio. The discourses from the research highlighted that the school leaving examination is hegemonised into South African educational pedagogy as a form of traditional assessment and is not challenged even when it is no longer bringing about the dominant ideological goals. The portfolio was not seen as an assessment method by the educators nor represented as such in the Curriculum Guide Directive. Therefore, the job of the portfolio became that of a policing tool. Thus, a school curriculum which has been introduced with the intent of furthering social justice can become exclusive in practice, even with the best intentions.
- Full Text:
- Date Issued: 2010
- Authors: Jones, Barbara Ellen
- Date: 2010
- Subjects: Discourse analysis -- South Africa -- Eastern Cape -- Case studies Competency-based education -- South Africa -- Eastern Cape -- Case studies Educational tests and measurements -- South Africa -- Eastern Cape -- Case studies Education -- Evaluation -- South Africa -- Eastern Cape -- Case studies Curriculum evaluation -- South Africa -- Eastern Cape -- Case studies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1468 , http://hdl.handle.net/10962/d1003349
- Description: In 1998, South Africa introduced outcomes-based education to affect the shifts in pedagogy considered necessary following the move to democracy in 1994. Across the globe, the use of the portfolio to assess learners is increasingly being promoted as a form of progressive pedagogy. Hence, its adoption by the country as a new form of assessment practice was warranted. However, how the portfolio is constructed and perceived by educators within the classroom can become problematic in practice. This was apparent in the South African context and justifies research into how the portfolio is constructed as an assessment method in educational policy and by educators in the classrooms. The Curriculum Guide Directive text and the transcripts of twenty-one interviews carried out in three Eastern Cape schools served as the source of data for this study. Discourses make up a powerful framework of spoken, written and symbolic texts of institutional bureaucracies. Within these institutions human subjects are defined and constructed. Therefore, discourse construction acts as institutional forms of knowledge which can exude power over the individual if not made transparent. I used critical discourse analysis to uncover the discourses that were embedded within the Curriculum Guide Directive and to identify the discourses entrenched within the educators’ perceptions of the portfolio. The discourses in the Curriculum Guide Directive suggest the construction of the portfolio as a method of surveillance to track whether the educators are preparing learners for the school leaving examination and instructing the educators to provide evidence in the form of a portfolio. Analysis of the transcripts of the twenty one interviews with educators from three schools in the Eastern Cape indicated that the portfolio was not seen as a form of assessment by the educators, but as a form of discipline put in place by the Department of Education to ensure that they are preparing the learners for the school leaving examination and are able to produce proof of this preparation in the form of a portfolio. The discourses from the research highlighted that the school leaving examination is hegemonised into South African educational pedagogy as a form of traditional assessment and is not challenged even when it is no longer bringing about the dominant ideological goals. The portfolio was not seen as an assessment method by the educators nor represented as such in the Curriculum Guide Directive. Therefore, the job of the portfolio became that of a policing tool. Thus, a school curriculum which has been introduced with the intent of furthering social justice can become exclusive in practice, even with the best intentions.
- Full Text:
- Date Issued: 2010
Consolidating democracy through integrating the chieftainship institution with elected councils in Lesotho: a case study of four community councils in Maseru
- Authors: Kapa, Motlamelle Anthony
- Date: 2010
- Subjects: Customary law -- Lesotho Constitutional law -- Lesotho Local government -- Lesotho -- Maseru Culture and law -- Lesotho -- Maseru Lesotho -- Politics and government Democracy -- Lesotho
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2786 , http://hdl.handle.net/10962/d1002996
- Description: This study analyses the relationship between the chieftainship institution and the elected councils in Lesotho. Based on a qualitative case study method the study seeks to understand this relationship in four selected councils in the Maseru district and how this can be nurtured to achieve a consolidated democracy. Contrary to modernists‟ arguments (that indigenous African political institutions, of which the chieftainship is part, are incompatible with liberal democracy since they are, inter alia, hereditary, they compete with their elective counterparts for political power, they threaten the democratic consolidation process, and they are irrelevant to democratising African systems), this study finds that these arguments are misplaced. Instead, chieftainship is not incompatible with liberal democracy per se. It supports the democratisation process (if the governing parties pursue friendly and accommodative policies to it) but uses its political agency in reaction to the policies of ruling parties to protect its survival interests, whether or not this undermines democratic consolidation process. The chieftainship has also acted to defend democracy when the governing party abuses its political power to undermine democratic rule. It performs important functions in the country. Thus, it is still viewed by the country‟s political leadership, academics, civil society, and councillors as legitimate and highly relevant to the Lesotho‟s contemporary political system. Because of the inadequacies of the government policies and the ambiguous chieftainship-councils integration model, which tend to marginalise the chieftainship and threaten its survival, its relationship with the councils was initially characterised by conflict. However, this relationship has improved, due to the innovative actions taken not by the central government, but by the individual Councils and chiefs themselves, thus increasing the prospects for democratic consolidation. I argue for and recommend the adoption in Lesotho of appropriate variants of the mixed government model to integrate the chieftainship with the elected councils, based on the re-contextualised and re-territorialised conception and practice of democracy, which eschews its universalistic EuroAmerican version adopted by the LCD government, but recognises and preserves the chieftainship as an integral part of the Basotho society, the embodiment of its culture, history, national identity and nationhood.
- Full Text:
- Date Issued: 2010
- Authors: Kapa, Motlamelle Anthony
- Date: 2010
- Subjects: Customary law -- Lesotho Constitutional law -- Lesotho Local government -- Lesotho -- Maseru Culture and law -- Lesotho -- Maseru Lesotho -- Politics and government Democracy -- Lesotho
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2786 , http://hdl.handle.net/10962/d1002996
- Description: This study analyses the relationship between the chieftainship institution and the elected councils in Lesotho. Based on a qualitative case study method the study seeks to understand this relationship in four selected councils in the Maseru district and how this can be nurtured to achieve a consolidated democracy. Contrary to modernists‟ arguments (that indigenous African political institutions, of which the chieftainship is part, are incompatible with liberal democracy since they are, inter alia, hereditary, they compete with their elective counterparts for political power, they threaten the democratic consolidation process, and they are irrelevant to democratising African systems), this study finds that these arguments are misplaced. Instead, chieftainship is not incompatible with liberal democracy per se. It supports the democratisation process (if the governing parties pursue friendly and accommodative policies to it) but uses its political agency in reaction to the policies of ruling parties to protect its survival interests, whether or not this undermines democratic consolidation process. The chieftainship has also acted to defend democracy when the governing party abuses its political power to undermine democratic rule. It performs important functions in the country. Thus, it is still viewed by the country‟s political leadership, academics, civil society, and councillors as legitimate and highly relevant to the Lesotho‟s contemporary political system. Because of the inadequacies of the government policies and the ambiguous chieftainship-councils integration model, which tend to marginalise the chieftainship and threaten its survival, its relationship with the councils was initially characterised by conflict. However, this relationship has improved, due to the innovative actions taken not by the central government, but by the individual Councils and chiefs themselves, thus increasing the prospects for democratic consolidation. I argue for and recommend the adoption in Lesotho of appropriate variants of the mixed government model to integrate the chieftainship with the elected councils, based on the re-contextualised and re-territorialised conception and practice of democracy, which eschews its universalistic EuroAmerican version adopted by the LCD government, but recognises and preserves the chieftainship as an integral part of the Basotho society, the embodiment of its culture, history, national identity and nationhood.
- Full Text:
- Date Issued: 2010
Formulation and evaluation of captopril loaded polymethacrylate and hydroxypropyl methycellulose microcapsules
- Khamanga, Sandile Maswazi Malungelo
- Authors: Khamanga, Sandile Maswazi Malungelo
- Date: 2010
- Subjects: Hypertension -- Treatment , Hypertension -- Chemotherapy , Angiotensin converting enzyme -- Inhibitors , Hypotensive agents -- Development , Pharmacokinetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3860 , http://hdl.handle.net/10962/d1013443
- Description: Angiotensin-converting enzyme (ACE) inhibitors are some of the most commonly prescribed medications for hypertension. They are cited in many papers as the treatment most often recommended by guidelines and favoured over other antihypertensive drugs as first-line agents especially when other high-risk conditions are present, such as diabetic nephropathy. The development of captopril (CPT) was amongst the earliest successes of the revolutionary concept of structure-based drug design. Due to its relatively poor pharmacokinetic profile or short half-life of about 1 hour, the formulation of sustained-release microcapsule dosage form is useful to improve patient compliance and to achieve predictable and optimized therapeutic plasma concentrations. Currently, CPT is mainly administered in tablet form. One of the difficulties of CPT formulation has been reported to be its instability in aqueous solutions. CPT is characterized by a lack of a strong chromophore and, therefore, not able to absorb at the more useful UV–Vis region of the spectrum. For this reason, an accurate, simple, reproducible, and sensitive HPLC-ECD method was developed and validated for the determination of CPT in dosage forms. The method was successfully applied for the determination of CPT in commercial and developed formulations. Possible drug-excipient and excipient-excipient interactions were investigated prior to formulating CPT microcapsules because successful formulation of a stable and effective solid dosage form depends on careful selection of excipients. Nuclear magnetic resonance spectroscopy, Fourier transform infra-red spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used for the identification and purity testing of CPT and excipients. The studies revealed no thermal changes during stress testing of binary and whole mixtures which indicate absence of solid state interactions. There were no shifts, appearance and disappearance in the endothermic or exothermic peaks and on the change of other associated enthalpy values on thermal curves obtained with DSC method. Characteristic peaks for common functional groups in the FT-IR were present in all the mixtures indicating the absence of incompatibility. The techniques used in this study can be said to have been efficient in the characterization and evaluation of the drug and excipients. The technique of microencapsulation by oil-in-oil was used to prepare CPT microcapsules. The effects of polymer molecular weight, homogenizing speed on the particle size, flow properties, morphology, surface properties and release characteristics of the prepared CPT microcapsules were examined. In order to decrease the complexity of the analysis and reduce cost response surface methodology using best polynomial equations was successfully used to quantify the effect of the formulation variables and develop an optimized formulation thereby minimizing the number of experimental trials. There was a burst effect during the first stage of dissolution. Scanning electron microscopy (SEM) results indicated that the initial burst effect observed in drug release could be attributed to dissolution of CPT crystals present at the surface or embedded in the superficial layer of the matrix. During the preparation of microcapsules, the drug might have been trapped near the surface of the microcapsules and or might have diffused quickly through the porous surface. The release kinetics of CPT from most formulations followed Fickian diffusion mechanism. SEM photographs showed that diffusion took place through pores at the surface of the microcapsules. The Kopcha model diffusion and erosion terms showed predominance of diffusion relative to swelling or erosion throughout the entire test period. Drug release mechanism was also confirmed by Makoid-Banakar and Korsmeyer-Peppas models exponents which further support diffusion release mechanism in most formulations. The models postulate that the total of drug release is a summation of a couple of mechanisms; burst release, relaxation induced controlled-release and diffusional release. Inspection of the 2D contour and 3D response surfaces allowed the determination of the geometrical nature of the surfaces and further providing results about the interaction of the different variables used in central composite design (CCD). The wide variation indicated that the factor combinations resulted in different drug release rates. Lagrange, canonical and mathematical modelling were used to determine the nature of the stationery point of the models. This represented the optimal variables or stationery points where there is interaction in the experimental space. It is difficult to understand the shape of a fitted response by mere inspection of the algebraic polynomial when there are many independent variables in the model. Canonical and Lagrange analyses facilitated the interpretation of the surface plots after a mathematical transformation of the original variables into new variables. In conclusion, these results suggest the potential application of Eudragit® / Methocel® microcapsules as suitable sustained-release drug delivery system for CPT.
- Full Text:
- Date Issued: 2010
- Authors: Khamanga, Sandile Maswazi Malungelo
- Date: 2010
- Subjects: Hypertension -- Treatment , Hypertension -- Chemotherapy , Angiotensin converting enzyme -- Inhibitors , Hypotensive agents -- Development , Pharmacokinetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3860 , http://hdl.handle.net/10962/d1013443
- Description: Angiotensin-converting enzyme (ACE) inhibitors are some of the most commonly prescribed medications for hypertension. They are cited in many papers as the treatment most often recommended by guidelines and favoured over other antihypertensive drugs as first-line agents especially when other high-risk conditions are present, such as diabetic nephropathy. The development of captopril (CPT) was amongst the earliest successes of the revolutionary concept of structure-based drug design. Due to its relatively poor pharmacokinetic profile or short half-life of about 1 hour, the formulation of sustained-release microcapsule dosage form is useful to improve patient compliance and to achieve predictable and optimized therapeutic plasma concentrations. Currently, CPT is mainly administered in tablet form. One of the difficulties of CPT formulation has been reported to be its instability in aqueous solutions. CPT is characterized by a lack of a strong chromophore and, therefore, not able to absorb at the more useful UV–Vis region of the spectrum. For this reason, an accurate, simple, reproducible, and sensitive HPLC-ECD method was developed and validated for the determination of CPT in dosage forms. The method was successfully applied for the determination of CPT in commercial and developed formulations. Possible drug-excipient and excipient-excipient interactions were investigated prior to formulating CPT microcapsules because successful formulation of a stable and effective solid dosage form depends on careful selection of excipients. Nuclear magnetic resonance spectroscopy, Fourier transform infra-red spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used for the identification and purity testing of CPT and excipients. The studies revealed no thermal changes during stress testing of binary and whole mixtures which indicate absence of solid state interactions. There were no shifts, appearance and disappearance in the endothermic or exothermic peaks and on the change of other associated enthalpy values on thermal curves obtained with DSC method. Characteristic peaks for common functional groups in the FT-IR were present in all the mixtures indicating the absence of incompatibility. The techniques used in this study can be said to have been efficient in the characterization and evaluation of the drug and excipients. The technique of microencapsulation by oil-in-oil was used to prepare CPT microcapsules. The effects of polymer molecular weight, homogenizing speed on the particle size, flow properties, morphology, surface properties and release characteristics of the prepared CPT microcapsules were examined. In order to decrease the complexity of the analysis and reduce cost response surface methodology using best polynomial equations was successfully used to quantify the effect of the formulation variables and develop an optimized formulation thereby minimizing the number of experimental trials. There was a burst effect during the first stage of dissolution. Scanning electron microscopy (SEM) results indicated that the initial burst effect observed in drug release could be attributed to dissolution of CPT crystals present at the surface or embedded in the superficial layer of the matrix. During the preparation of microcapsules, the drug might have been trapped near the surface of the microcapsules and or might have diffused quickly through the porous surface. The release kinetics of CPT from most formulations followed Fickian diffusion mechanism. SEM photographs showed that diffusion took place through pores at the surface of the microcapsules. The Kopcha model diffusion and erosion terms showed predominance of diffusion relative to swelling or erosion throughout the entire test period. Drug release mechanism was also confirmed by Makoid-Banakar and Korsmeyer-Peppas models exponents which further support diffusion release mechanism in most formulations. The models postulate that the total of drug release is a summation of a couple of mechanisms; burst release, relaxation induced controlled-release and diffusional release. Inspection of the 2D contour and 3D response surfaces allowed the determination of the geometrical nature of the surfaces and further providing results about the interaction of the different variables used in central composite design (CCD). The wide variation indicated that the factor combinations resulted in different drug release rates. Lagrange, canonical and mathematical modelling were used to determine the nature of the stationery point of the models. This represented the optimal variables or stationery points where there is interaction in the experimental space. It is difficult to understand the shape of a fitted response by mere inspection of the algebraic polynomial when there are many independent variables in the model. Canonical and Lagrange analyses facilitated the interpretation of the surface plots after a mathematical transformation of the original variables into new variables. In conclusion, these results suggest the potential application of Eudragit® / Methocel® microcapsules as suitable sustained-release drug delivery system for CPT.
- Full Text:
- Date Issued: 2010
Studies on the nutritional value of seven accessions of cocoyam growing in South Africa
- Authors: Lewu, Muinat Nike
- Date: 2010
- Subjects: Taro , Nutrition , Field crops -- Nutrition , Taro -- Nutritional aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11305 , http://hdl.handle.net/10353/d1001054 , Taro , Nutrition , Field crops -- Nutrition , Taro -- Nutritional aspects
- Description: Cocoyam [Colocasia esculenta (L.) Schott] is widely cultivated as a staple food in the tropical and subtropical regions of the world. The crop, however, remains unpopular and not well known outside KwaZulu-Natal Province of South Africa where it is cultivated mainly for subsistence. The aims of the study were to collect local landraces (accessions) of the crop from where it is found growing within the country for various studies and also to document its nutritional values as well as the safety/toxicity of the crop. The study was carried out using various methods. These included a comparative assessment of the proximate, mineral and antinutrient compositions of cooked and uncooked tubers of a typical commercially available cocoyam and potato found in South African markets. These investigations were repeated for the tubers and leaves of available landraces (seven accessions) of C. esculenta found growing in the farmers’ fields in KwaZulu-Natal Province. Also, an in vivo toxicological study on cooked accessions of the local landraces was conducted to determine possible toxicity effects after consumption using albino rats as a model. The results revealed that commercially available cocoyam and potato tubers have very close nutritional components. Analysis of the proximate composition of seven accessions (UFCe1- UFCe7) of cooked and uncooked tubers of cocoyam indicated that UFCe7 was better in ash, crude protein, crude fibre and crude lipid contents but with higher moisture which could make it more vulnerable to microbial attack. No tubers of the seven accessions appeared to be ii outstandingly better than the others based on their mineral compositions. However, in terms of antinutritional factors, UFCe1, UFCe3 and UFCe7 had the least amounts of oxalate, tannins and phytate in their cooked states. It was discovered however, that the leaves of the accessions of this vegetable contain substantial amount of minerals, and therefore, can contribute significantly to the nutrient requirements of humans and could be recommended as a cheap source of nutrients in South Africa. None of the accessions was outstandingly better than the others in terms of their mineral contents and anti-nutritional factors. Moreover, the current study has shown that boiling the leaves of cocoyam prior to consumption is an effective way of reducing the antinutrient contents of the leaves of the plant thereby making it safe for consumption. The findings also revealed that cooking C. esculenta leaves may increase the levels of protein, fibre and lipid contents while cooking may also decrease the mineral, carbohydrate and caloric contents of the leaves of the accessions. The leafy vegetable may, therefore, be recommended as a cheap source of plant protein. Cooking improved the nutritive value as a result of the reduction in antinutrient levels, thereby improving the food quality in all the tuber and leaf samples used for this study. At the same time, cooked samples also suffered loss of some nutrients with respect to the proximate and mineral compositions. However, supplementation from other food sources that are rich in these nutrients is necessary when these crops are cooked for consumption. Any of the cocoyam accessions may be recommended for consumption for improved protein and mineral nutrients while tubers of accession UFCe7 have also shown good promise in terms of protein and fibre content availability. The results of the in vivo study, using the liver and kidney functional endpoints of weanling albino rats (Rattus norvegicus) maintained on different accessions of cooked cocoyam-based iii diets (UFCe1-UFCe7) for 28 days, revealed that all the accessions produced selective alterations on the hepatorenal indices of weanling rats. The highest alterations were produced by UFCe4 while the least was from UFCe2. These alterations may have consequential effects on the normal functioning of the liver and kidney of the animals. The UFCe2 exhibited the least toxicity risk among the accessions of C. esculenta growing in KwaZulu-Natal Province of South Africa.
- Full Text:
- Date Issued: 2010
- Authors: Lewu, Muinat Nike
- Date: 2010
- Subjects: Taro , Nutrition , Field crops -- Nutrition , Taro -- Nutritional aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11305 , http://hdl.handle.net/10353/d1001054 , Taro , Nutrition , Field crops -- Nutrition , Taro -- Nutritional aspects
- Description: Cocoyam [Colocasia esculenta (L.) Schott] is widely cultivated as a staple food in the tropical and subtropical regions of the world. The crop, however, remains unpopular and not well known outside KwaZulu-Natal Province of South Africa where it is cultivated mainly for subsistence. The aims of the study were to collect local landraces (accessions) of the crop from where it is found growing within the country for various studies and also to document its nutritional values as well as the safety/toxicity of the crop. The study was carried out using various methods. These included a comparative assessment of the proximate, mineral and antinutrient compositions of cooked and uncooked tubers of a typical commercially available cocoyam and potato found in South African markets. These investigations were repeated for the tubers and leaves of available landraces (seven accessions) of C. esculenta found growing in the farmers’ fields in KwaZulu-Natal Province. Also, an in vivo toxicological study on cooked accessions of the local landraces was conducted to determine possible toxicity effects after consumption using albino rats as a model. The results revealed that commercially available cocoyam and potato tubers have very close nutritional components. Analysis of the proximate composition of seven accessions (UFCe1- UFCe7) of cooked and uncooked tubers of cocoyam indicated that UFCe7 was better in ash, crude protein, crude fibre and crude lipid contents but with higher moisture which could make it more vulnerable to microbial attack. No tubers of the seven accessions appeared to be ii outstandingly better than the others based on their mineral compositions. However, in terms of antinutritional factors, UFCe1, UFCe3 and UFCe7 had the least amounts of oxalate, tannins and phytate in their cooked states. It was discovered however, that the leaves of the accessions of this vegetable contain substantial amount of minerals, and therefore, can contribute significantly to the nutrient requirements of humans and could be recommended as a cheap source of nutrients in South Africa. None of the accessions was outstandingly better than the others in terms of their mineral contents and anti-nutritional factors. Moreover, the current study has shown that boiling the leaves of cocoyam prior to consumption is an effective way of reducing the antinutrient contents of the leaves of the plant thereby making it safe for consumption. The findings also revealed that cooking C. esculenta leaves may increase the levels of protein, fibre and lipid contents while cooking may also decrease the mineral, carbohydrate and caloric contents of the leaves of the accessions. The leafy vegetable may, therefore, be recommended as a cheap source of plant protein. Cooking improved the nutritive value as a result of the reduction in antinutrient levels, thereby improving the food quality in all the tuber and leaf samples used for this study. At the same time, cooked samples also suffered loss of some nutrients with respect to the proximate and mineral compositions. However, supplementation from other food sources that are rich in these nutrients is necessary when these crops are cooked for consumption. Any of the cocoyam accessions may be recommended for consumption for improved protein and mineral nutrients while tubers of accession UFCe7 have also shown good promise in terms of protein and fibre content availability. The results of the in vivo study, using the liver and kidney functional endpoints of weanling albino rats (Rattus norvegicus) maintained on different accessions of cooked cocoyam-based iii diets (UFCe1-UFCe7) for 28 days, revealed that all the accessions produced selective alterations on the hepatorenal indices of weanling rats. The highest alterations were produced by UFCe4 while the least was from UFCe2. These alterations may have consequential effects on the normal functioning of the liver and kidney of the animals. The UFCe2 exhibited the least toxicity risk among the accessions of C. esculenta growing in KwaZulu-Natal Province of South Africa.
- Full Text:
- Date Issued: 2010
The characterisation of trypanosomal type 1 DnaJ-like proteins
- Authors: Ludewig, Michael Hans
- Date: 2010
- Subjects: Molecular genetics , Molecular chaperones , Protozoa , Heat shock proteins , Trypanosoma
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4126 , http://hdl.handle.net/10962/d1015205
- Description: Trypanosomes are protozoans, of which many are parasitic, and possess complex lifecycles which alternate between mammalian and arthropod hosts. As is the case with most organisms, molecular chaperones and heat shock proteins are encoded within the genomes of these protozoans. These proteins are an integral part of maintaining the structural integrity of proteins during normal and stress conditions. Heat shock protein 40 (Hsp40) is a co-chaperone of heat shock protein 70 (Hsp70) and in some cases can act as a chaperone. These proteins work together to bind non-native polypeptide structures to prevent unfolded protein aggregrate formation in times of stress, translocate proteins across organelle membranes, and transport unsalvageable proteins to proteolytic degradation by the cellular proteasome. Hsp40s are divided into four types based on their domain structure. Analysis of the nuclear genomes of eight trypanosomatid species revealed that less than 10 of the approximate 70 Hsp40 sequences per genome were Type 1 Hsp40s, many of which contained putative orthologues in the other seven trypanosomatid genomes. One of these Type 1 Hsp40s from T b. brucei, Trypanosoma brucei DnaJ 2 (Tbj2), was functionally characterised in T brucei brucei. RNA interference knockdown of expression in T brucei brucei showed that cells deficient in Tbj2 displayed a severe inhibition of the growth of the cell population. The levels of the Tbj2 protein population in T brucei brucei cells increases after exposure to 42°c and the protein was found to have a generalized cytoplasmic subcellular localization at 37°c. These findings provide evidence that Tbj2 is an orthologue of Yeast DnaJ 1 (Y dj l), an essential S. cerevisiae protein. Hsp40s interact with their partner Hsp70s through their J-domain. The amino acids of the J-domain important for a functional interaction with Hsp70 were examined in Trypanosoma cruzi DnaJ 2 (Tcj2) (the orthologue of Tbj2) and T cruzi DnaJ protein 3 (Tcj3) by testing their ability to substitute for Y dj l in Saccharomyces cerevisae and for DnaJ in Escherichia coli. In both systems, the positively charged amino acids of Helix II and III of the J-domain disrupted the functional interaction of these Hsp40s with their partner Hsp70s. Substitutions in Helix I and IV of the J-domains of Tcj2 and Tcj3 produced varied results in the two different systems, possibly suggesting that these helices serve to define with which Hsp70s a given Hsp40 can interact. The inability of an Hsp40 and an Hsp70 to interact functionally does not necessarily mean a total absence of physical interaction between these proteins. The amino acid substitution of the histidine in the HPD motif (H34Q) of the J-domain of Tcj2 and Tcj3 removed the ability of these proteins to interact functionally with S. cerevisiae Hsp70 (Ssal) in vivo. However, preliminary binding studies using the quartz crystal microbalance with dissipation monitoring (QCM-D) show that Tcj2 and Tcj2(H34Q) both physically interact with M sativa Hsp70 in vitro. This study is the first report to provide evidence that certain trypanosoma! Type 1 Hsp40s are essential proteins. Futhermore, the interaction of these Hsp40s with Hsp70 identified important features of the functional interface of this chaperone machinery.
- Full Text:
- Date Issued: 2010
- Authors: Ludewig, Michael Hans
- Date: 2010
- Subjects: Molecular genetics , Molecular chaperones , Protozoa , Heat shock proteins , Trypanosoma
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4126 , http://hdl.handle.net/10962/d1015205
- Description: Trypanosomes are protozoans, of which many are parasitic, and possess complex lifecycles which alternate between mammalian and arthropod hosts. As is the case with most organisms, molecular chaperones and heat shock proteins are encoded within the genomes of these protozoans. These proteins are an integral part of maintaining the structural integrity of proteins during normal and stress conditions. Heat shock protein 40 (Hsp40) is a co-chaperone of heat shock protein 70 (Hsp70) and in some cases can act as a chaperone. These proteins work together to bind non-native polypeptide structures to prevent unfolded protein aggregrate formation in times of stress, translocate proteins across organelle membranes, and transport unsalvageable proteins to proteolytic degradation by the cellular proteasome. Hsp40s are divided into four types based on their domain structure. Analysis of the nuclear genomes of eight trypanosomatid species revealed that less than 10 of the approximate 70 Hsp40 sequences per genome were Type 1 Hsp40s, many of which contained putative orthologues in the other seven trypanosomatid genomes. One of these Type 1 Hsp40s from T b. brucei, Trypanosoma brucei DnaJ 2 (Tbj2), was functionally characterised in T brucei brucei. RNA interference knockdown of expression in T brucei brucei showed that cells deficient in Tbj2 displayed a severe inhibition of the growth of the cell population. The levels of the Tbj2 protein population in T brucei brucei cells increases after exposure to 42°c and the protein was found to have a generalized cytoplasmic subcellular localization at 37°c. These findings provide evidence that Tbj2 is an orthologue of Yeast DnaJ 1 (Y dj l), an essential S. cerevisiae protein. Hsp40s interact with their partner Hsp70s through their J-domain. The amino acids of the J-domain important for a functional interaction with Hsp70 were examined in Trypanosoma cruzi DnaJ 2 (Tcj2) (the orthologue of Tbj2) and T cruzi DnaJ protein 3 (Tcj3) by testing their ability to substitute for Y dj l in Saccharomyces cerevisae and for DnaJ in Escherichia coli. In both systems, the positively charged amino acids of Helix II and III of the J-domain disrupted the functional interaction of these Hsp40s with their partner Hsp70s. Substitutions in Helix I and IV of the J-domains of Tcj2 and Tcj3 produced varied results in the two different systems, possibly suggesting that these helices serve to define with which Hsp70s a given Hsp40 can interact. The inability of an Hsp40 and an Hsp70 to interact functionally does not necessarily mean a total absence of physical interaction between these proteins. The amino acid substitution of the histidine in the HPD motif (H34Q) of the J-domain of Tcj2 and Tcj3 removed the ability of these proteins to interact functionally with S. cerevisiae Hsp70 (Ssal) in vivo. However, preliminary binding studies using the quartz crystal microbalance with dissipation monitoring (QCM-D) show that Tcj2 and Tcj2(H34Q) both physically interact with M sativa Hsp70 in vitro. This study is the first report to provide evidence that certain trypanosoma! Type 1 Hsp40s are essential proteins. Futhermore, the interaction of these Hsp40s with Hsp70 identified important features of the functional interface of this chaperone machinery.
- Full Text:
- Date Issued: 2010
Metallophthalocyanines as electrocatalysts and superoxide dismutase mimics
- Authors: Matemadombo, Fungisai
- Date: 2010
- Subjects: Mimicry (Chemistry) Electrocatalysis Superoxide dismutase Electrochemistry Phthalocyanines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4325 , http://hdl.handle.net/10962/d1004985
- Description: Syntheses, spectral, electrochemical, and spectroelectrochemical studies of iron, cobalt, and manganese phthalocyanines are reported. The novel coordination of cobalt tetracarboxy metallophthalocyanine to an electrode premodified with aryl radicals and its use in the detection of thiocyanate are reported. This work describes the catalytic activity of cobalt phthalocyanine (CoPc) derivatives adsorbed onto glassy carbon electrodes for the electrocatalytical detection of nitrite, Lcysteine, and melatonin. The modified electrodes efficiently detected nitrite. The CoPc derivative modified electrodes proficiently detected L-cysteine whereas an un-modified electrode could not. This work presents the innovative electrochemical detection of melatonin using electrodes adsorbed with CoPc derivatives. These electrodes detected melatonin at more favorable electrochemical parameters relative to an un-modified gold electrode. The limits of melatonin detection of the modified electrodes lay in the 10⁻⁷ to 10⁻⁶ M region. The modified electrodes accurately detected capsule melatonin concentrations as specified by the supplier and could differentiate between a mixture of melatonin, tryptophan, and ascorbic acid. They reliably detected nitrite, L-cysteine, and melatonin in the 10⁻⁴ to 10⁻² M region. Metallophthalocyanine complexes substituted with thio groups were employed as self assembled monolayers (SAMs). Voltammetry, impedance, atomic force microscopy, and scanning electrochemical microscopy proved that the SAMs all act as selective and efficient barriers to ion permeability. All the SAMs in this work can be used as effective electrochemical sensors of nitrite and L-cysteine in the 10⁻⁴ to 10⁻² M region with competitive limits of detection whereas an un-modified electrode cannot detect Lcysteine. The manganese phthalocyanine SAM modified electrodes are arguably better nitrite and L-cysteine electrocatalysts relative to their iron and cobalt counterparts. Manganese phthalocyanines were used as superoxide dismutase (SOD) mimics. All manganese phthalocyanine complexes in this work acted as SOD mimics in an enzymatic system of superoxide production. From cellular studies, complexes 6d, 6e, 8d, 8e act as intracellular SOD mimics and are without significantly high cellular toxicity.
- Full Text:
- Date Issued: 2010
- Authors: Matemadombo, Fungisai
- Date: 2010
- Subjects: Mimicry (Chemistry) Electrocatalysis Superoxide dismutase Electrochemistry Phthalocyanines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4325 , http://hdl.handle.net/10962/d1004985
- Description: Syntheses, spectral, electrochemical, and spectroelectrochemical studies of iron, cobalt, and manganese phthalocyanines are reported. The novel coordination of cobalt tetracarboxy metallophthalocyanine to an electrode premodified with aryl radicals and its use in the detection of thiocyanate are reported. This work describes the catalytic activity of cobalt phthalocyanine (CoPc) derivatives adsorbed onto glassy carbon electrodes for the electrocatalytical detection of nitrite, Lcysteine, and melatonin. The modified electrodes efficiently detected nitrite. The CoPc derivative modified electrodes proficiently detected L-cysteine whereas an un-modified electrode could not. This work presents the innovative electrochemical detection of melatonin using electrodes adsorbed with CoPc derivatives. These electrodes detected melatonin at more favorable electrochemical parameters relative to an un-modified gold electrode. The limits of melatonin detection of the modified electrodes lay in the 10⁻⁷ to 10⁻⁶ M region. The modified electrodes accurately detected capsule melatonin concentrations as specified by the supplier and could differentiate between a mixture of melatonin, tryptophan, and ascorbic acid. They reliably detected nitrite, L-cysteine, and melatonin in the 10⁻⁴ to 10⁻² M region. Metallophthalocyanine complexes substituted with thio groups were employed as self assembled monolayers (SAMs). Voltammetry, impedance, atomic force microscopy, and scanning electrochemical microscopy proved that the SAMs all act as selective and efficient barriers to ion permeability. All the SAMs in this work can be used as effective electrochemical sensors of nitrite and L-cysteine in the 10⁻⁴ to 10⁻² M region with competitive limits of detection whereas an un-modified electrode cannot detect Lcysteine. The manganese phthalocyanine SAM modified electrodes are arguably better nitrite and L-cysteine electrocatalysts relative to their iron and cobalt counterparts. Manganese phthalocyanines were used as superoxide dismutase (SOD) mimics. All manganese phthalocyanine complexes in this work acted as SOD mimics in an enzymatic system of superoxide production. From cellular studies, complexes 6d, 6e, 8d, 8e act as intracellular SOD mimics and are without significantly high cellular toxicity.
- Full Text:
- Date Issued: 2010
Towards social impact assessment of copper-nickel mining in Botswana
- Authors: Mengwe, Moses Seargent
- Date: 2010
- Subjects: Copper mines and mining -- Environmental aspects -- Botswana , Nickel mines and mining -- Environmental aspects -- Botswana , Mineral industry -- Botswana , Mines and mineral resources -- Botswana
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10644 , http://hdl.handle.net/10948/1443 , Copper mines and mining -- Environmental aspects -- Botswana , Nickel mines and mining -- Environmental aspects -- Botswana , Mineral industry -- Botswana , Mines and mineral resources -- Botswana
- Description: This research study is more of an initiative towards Social Impact Assessment of copper-nickel mining in Botswana. The specific objectives of the study were centred on the assessment of the social impacts of copper-nickel mining in Botswana from the initial mining stage of exploration, surveying and mine site development to mine closure. The study was carried out under the broad hypotheses that mining influences population movement that impact on areas of mining; mining activities have both economic benefits and deleterious social impacts on the local communities found in the areas where mining is taking place; and mine closure has far reaching socio-economic, investment and developmental implications over and above the obvious interests of project owners. To achieve the broad aim as summarised above, the research study used a multi-disciplinary methodology and approach that required several kinds of expertise and sources of information. Hence it used both primary and secondary sources centred on interactive informative interviews, site visits and observations, questionnaires, census data records, mining companies’ publications, published textbooks and journal articles. The research study comprised of three different mines operated by three different mining companies in three varied socio-cultural and ethnic regions of Botswana. First was a detailed Social Impact Assessment of the initial phase of exploration, surveying and mine site development represented by Mowana mine project operated by African Copper in the rural areas of Dugwi and Mosetse. This case study yielded results showing that the social impacts of mining in the area are diverse and extensive. The findings suggest that the impacts relate not only to the possible economic benefits of foreign exchange, employment, the optimal use of available mineral resources and the possible development of Dugwi and Mosetse villages, but extends to the deleterious social impacts. The results also indicated that the social impacts have just begun in the two communities. Hence they point towards a possible disruption within the socio-cultural system of the local people if serious mitigation measures are not put in place; thus suggesting that the early stages of exploration and mine site development results in the most conflict between the mine and the local people. Second was a comprehensive Social Impact Assessment of Tati-Nickel Phoenix mining project in the peri-urban areas of Matshelagabedi and Matsiloje areas representing the mining stage of mine production and expansion. The results from this case study suggest that during vi mine production and expansion, many people were relocated. However, the overriding impression gained from the case study was Tati-Nickel Mining Company’s elaborate corporate policies that suggested good corporate governance and best practices that promote sustainable development. A notable milestone on good corporate governance and best practice that the other two case studies (mining company) could benchmark on is Tati-Nickel’s corporate social responsibility programme that has been designed to ensure that the communities within a fifty kilometre mine radius benefit from the mine. The results from the case study also distinguished the mining stage of production and expansion from the other two because it is associated with the deep entrenchment of the social impacts into the communities near to mining areas. Third was a detailed Social Impact Assessment on Bamangwato Concession Limited mine in the industrial town of Selebi-Phikwe. The case study represented the stage of mine closure. Through the findings of this case study, it became apparent that the economic dependence of Selebi-Phikwe on mining has seen the town developing into a mining town, increasing its vulnerability at mine closure. The results from the case study further suggest that mine closure will degrade the socio-economic sector of the town with ever far reaching socio-economic implications as many people lose their gainful employment, hence suggesting that a possible complete mine closure will be the most traumatic phase leading to major social conflict within the area. Thus the results suggest that at mine closure, the deleterious social impacts will overspill to other areas in Botswana with disastrous effects for the economy of the country. The results yielded through this study established in clear and passionate language that copper-nickel mining in Botswana influences population movements that lead to positive and negative impacts on the communities found in mining areas. Another major finding of the study is that copper-nickel mining activities have both economic benefits and deleterious social impacts on the local communities, hence the recommendation that the copper-nickel mining companies should embrace the concept of sustainable mining for sustainable development to avoid most of the negative impacts of their operations on the local communities.
- Full Text:
- Date Issued: 2010
- Authors: Mengwe, Moses Seargent
- Date: 2010
- Subjects: Copper mines and mining -- Environmental aspects -- Botswana , Nickel mines and mining -- Environmental aspects -- Botswana , Mineral industry -- Botswana , Mines and mineral resources -- Botswana
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10644 , http://hdl.handle.net/10948/1443 , Copper mines and mining -- Environmental aspects -- Botswana , Nickel mines and mining -- Environmental aspects -- Botswana , Mineral industry -- Botswana , Mines and mineral resources -- Botswana
- Description: This research study is more of an initiative towards Social Impact Assessment of copper-nickel mining in Botswana. The specific objectives of the study were centred on the assessment of the social impacts of copper-nickel mining in Botswana from the initial mining stage of exploration, surveying and mine site development to mine closure. The study was carried out under the broad hypotheses that mining influences population movement that impact on areas of mining; mining activities have both economic benefits and deleterious social impacts on the local communities found in the areas where mining is taking place; and mine closure has far reaching socio-economic, investment and developmental implications over and above the obvious interests of project owners. To achieve the broad aim as summarised above, the research study used a multi-disciplinary methodology and approach that required several kinds of expertise and sources of information. Hence it used both primary and secondary sources centred on interactive informative interviews, site visits and observations, questionnaires, census data records, mining companies’ publications, published textbooks and journal articles. The research study comprised of three different mines operated by three different mining companies in three varied socio-cultural and ethnic regions of Botswana. First was a detailed Social Impact Assessment of the initial phase of exploration, surveying and mine site development represented by Mowana mine project operated by African Copper in the rural areas of Dugwi and Mosetse. This case study yielded results showing that the social impacts of mining in the area are diverse and extensive. The findings suggest that the impacts relate not only to the possible economic benefits of foreign exchange, employment, the optimal use of available mineral resources and the possible development of Dugwi and Mosetse villages, but extends to the deleterious social impacts. The results also indicated that the social impacts have just begun in the two communities. Hence they point towards a possible disruption within the socio-cultural system of the local people if serious mitigation measures are not put in place; thus suggesting that the early stages of exploration and mine site development results in the most conflict between the mine and the local people. Second was a comprehensive Social Impact Assessment of Tati-Nickel Phoenix mining project in the peri-urban areas of Matshelagabedi and Matsiloje areas representing the mining stage of mine production and expansion. The results from this case study suggest that during vi mine production and expansion, many people were relocated. However, the overriding impression gained from the case study was Tati-Nickel Mining Company’s elaborate corporate policies that suggested good corporate governance and best practices that promote sustainable development. A notable milestone on good corporate governance and best practice that the other two case studies (mining company) could benchmark on is Tati-Nickel’s corporate social responsibility programme that has been designed to ensure that the communities within a fifty kilometre mine radius benefit from the mine. The results from the case study also distinguished the mining stage of production and expansion from the other two because it is associated with the deep entrenchment of the social impacts into the communities near to mining areas. Third was a detailed Social Impact Assessment on Bamangwato Concession Limited mine in the industrial town of Selebi-Phikwe. The case study represented the stage of mine closure. Through the findings of this case study, it became apparent that the economic dependence of Selebi-Phikwe on mining has seen the town developing into a mining town, increasing its vulnerability at mine closure. The results from the case study further suggest that mine closure will degrade the socio-economic sector of the town with ever far reaching socio-economic implications as many people lose their gainful employment, hence suggesting that a possible complete mine closure will be the most traumatic phase leading to major social conflict within the area. Thus the results suggest that at mine closure, the deleterious social impacts will overspill to other areas in Botswana with disastrous effects for the economy of the country. The results yielded through this study established in clear and passionate language that copper-nickel mining in Botswana influences population movements that lead to positive and negative impacts on the communities found in mining areas. Another major finding of the study is that copper-nickel mining activities have both economic benefits and deleterious social impacts on the local communities, hence the recommendation that the copper-nickel mining companies should embrace the concept of sustainable mining for sustainable development to avoid most of the negative impacts of their operations on the local communities.
- Full Text:
- Date Issued: 2010
Sample preparation for pesticide analysis in water and sediments a case study of the Okavango Delta, Botswana
- Authors: Mmualefe, Lesego Cecilia
- Date: 2010
- Subjects: Water quality -- Botswana -- Okavango Delta Water -- Analysis Pesticides -- Environmental aspects -- Botswana -- Okavango Delta Water -- Pollution -- Botswana -- Okavango Delta DDT (Insecticide) -- Environmental aspects -- Botswana -- Okavango Delta
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4344 , http://hdl.handle.net/10962/d1005006
- Description: This thesis presents a first ever extensive analysis of pesticides in water and sediments from the Okavango Delta, Botswana, employing green sample preparation techniques that require small volumes of organic solvents hence generating negligible volumes of organic solvent waste. Pesticides were extracted and pre-concentrated from water by solid phase extraction (SPE) and headspace solid phase microextraction (HS-SPME) while supercritical fluid extraction (SFE) and pressurized fluid extraction (PFE) were employed for sediments. Subsequent analysis was carried out on a gas chromatograph with electron capture detection and analytes were unequivocally confirmed by high resolution mass spectrometric detection. Hexachlorobenzene (HCB), trans-chlordane, 4,4′-DDD and 4,4′-DDE were detected after optimized HS-SPME in several water samples from the lower Delta at concentrations ranging from 2.4 to 61.4 μg L-1 that are much higher than the 0.1 μg L-1 maximum limit of individual organochlorine pesticides in drinking water set by the European Community Directive. The same samples were cleaned with ISOLUTE C18 SPE sorbent with an optimal acetone/n-hexane (1:1 v/v) mixture for the elution of analytes. No pesticides were detected after SPE clean-up and pre-concentration. HCB, aldrin and 4, 4‟-DDT were identified in sediments after SFE at concentration ranges of 1.1 - 30.3, 0.5 – 15.2 and 1.4 – 55.4 μg/g, respectively. There was an increase of pesticides concentrations in the direction of water flow from the Panhandle (point of entry) to the lower delta. DDE, fatty acids and phthalates were detected after PFE with optimized extraction solvent and temperature. The presence of DDT metabolites in the water and sediments from the Okavango Delta confirm historical exposure to the pesticide. However their cumulative concentration increase in the water-flow direction calls for further investigation of point sources for the long-term preservation of the Delta. The green sample preparation techniques and low toxicity solvents employed in this thesis are thus recommended for routine environmental monitoring exercises.
- Full Text:
- Date Issued: 2010
- Authors: Mmualefe, Lesego Cecilia
- Date: 2010
- Subjects: Water quality -- Botswana -- Okavango Delta Water -- Analysis Pesticides -- Environmental aspects -- Botswana -- Okavango Delta Water -- Pollution -- Botswana -- Okavango Delta DDT (Insecticide) -- Environmental aspects -- Botswana -- Okavango Delta
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4344 , http://hdl.handle.net/10962/d1005006
- Description: This thesis presents a first ever extensive analysis of pesticides in water and sediments from the Okavango Delta, Botswana, employing green sample preparation techniques that require small volumes of organic solvents hence generating negligible volumes of organic solvent waste. Pesticides were extracted and pre-concentrated from water by solid phase extraction (SPE) and headspace solid phase microextraction (HS-SPME) while supercritical fluid extraction (SFE) and pressurized fluid extraction (PFE) were employed for sediments. Subsequent analysis was carried out on a gas chromatograph with electron capture detection and analytes were unequivocally confirmed by high resolution mass spectrometric detection. Hexachlorobenzene (HCB), trans-chlordane, 4,4′-DDD and 4,4′-DDE were detected after optimized HS-SPME in several water samples from the lower Delta at concentrations ranging from 2.4 to 61.4 μg L-1 that are much higher than the 0.1 μg L-1 maximum limit of individual organochlorine pesticides in drinking water set by the European Community Directive. The same samples were cleaned with ISOLUTE C18 SPE sorbent with an optimal acetone/n-hexane (1:1 v/v) mixture for the elution of analytes. No pesticides were detected after SPE clean-up and pre-concentration. HCB, aldrin and 4, 4‟-DDT were identified in sediments after SFE at concentration ranges of 1.1 - 30.3, 0.5 – 15.2 and 1.4 – 55.4 μg/g, respectively. There was an increase of pesticides concentrations in the direction of water flow from the Panhandle (point of entry) to the lower delta. DDE, fatty acids and phthalates were detected after PFE with optimized extraction solvent and temperature. The presence of DDT metabolites in the water and sediments from the Okavango Delta confirm historical exposure to the pesticide. However their cumulative concentration increase in the water-flow direction calls for further investigation of point sources for the long-term preservation of the Delta. The green sample preparation techniques and low toxicity solvents employed in this thesis are thus recommended for routine environmental monitoring exercises.
- Full Text:
- Date Issued: 2010
Leonotis leonurus: the anticoagulant and antidiabetic activity of Leonotis leonurus
- Authors: Mnonopi, Nandipha
- Date: 2010
- Subjects: Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , Diabetes -- Alternative treatment -- South Africa , Plant bioactive compounds , Leonotis leonurus -- Physiological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10323 , http://hdl.handle.net/10948/1194 , Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , Diabetes -- Alternative treatment -- South Africa , Plant bioactive compounds , Leonotis leonurus -- Physiological aspects
- Description: Commercial marrubiin, aqueous and organic extracts of Leonotis leonurus were tested in vitro for their anticoagulant and antiplatelet activities. The aqueous extract inhibited platelet aggregation by 69.5 percent (100 μg/mL), while the organic extract (100 μg/mL) and marrubiin (5 μg/mL) showed 92.5 percent and 91.6 percent inhibition, respectively, by inhibiting the binding of fibrinogen to glycoprotein IIb/IIIa receptor in a concentration dependent manner. The extracts significantly prolonged activated partial thromboplastin time compared to untreated plasma controls. Fibrin and D-Dimer formation were drastically decreased. The extracts and marrubiin concentration-dependently inhibited calcium mobilization induced by collagen and thrombin. The formation of thromboxane A2 was also significantly reduced by both the extracts and marrubiin. Protein secretion and platelet adhesion were significantly reduced by both the extracts and marrubiin. The organic extract and marrubiin showed a more pronounced effect than the aqueous extracts in all the in vitro assays. The ex-vivo animal model confirmed the results obtained in vitro. Similar to the in vitro studies, activated partial thromboplastin time clotting time was prolonged by marrubiin and the number of aggregated platelets were significantly reduced relative to aspirin. The findings reflect that marrubiin largely contributes to the organic extract's anticoagulant and antiplatelet effect in vitro. INS-1 cells were cultured under normo- and hyperglycaemic conditions. Marrubiin and the two Leonotis leonurus extracts were screened for anti-diabetic activity in vitro. The stimulatory index of INS-1 cells cultured under hyperglycaemic conditions was significantly increased by 60 percent and 61 percent (p<0.01; n=5) in cells exposed to the organic extract (10 μg/mL) and marrubiin (500 ng/mL), respectively, relative to the normoglycaemic conditions. The gene expression of insulin was significantly increased by 76.5 and 71 percent, and of glucose transporter-2 by 93 and 92.5 percent for marrubiin and the organic extract, respectively, under the same conditions stipulated above (p<0.01; n=4). The extract and marrubiin similarly showed an increase in respiratory rate under hyperglycaemic conditions. Marrubiin increased insulin secretion, HDL-cholesterol, while it decreased total cholesterol, LDL-cholesterol and the atherogenic index in the in vivo rat model.
- Full Text:
- Date Issued: 2010
- Authors: Mnonopi, Nandipha
- Date: 2010
- Subjects: Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , Diabetes -- Alternative treatment -- South Africa , Plant bioactive compounds , Leonotis leonurus -- Physiological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10323 , http://hdl.handle.net/10948/1194 , Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , Diabetes -- Alternative treatment -- South Africa , Plant bioactive compounds , Leonotis leonurus -- Physiological aspects
- Description: Commercial marrubiin, aqueous and organic extracts of Leonotis leonurus were tested in vitro for their anticoagulant and antiplatelet activities. The aqueous extract inhibited platelet aggregation by 69.5 percent (100 μg/mL), while the organic extract (100 μg/mL) and marrubiin (5 μg/mL) showed 92.5 percent and 91.6 percent inhibition, respectively, by inhibiting the binding of fibrinogen to glycoprotein IIb/IIIa receptor in a concentration dependent manner. The extracts significantly prolonged activated partial thromboplastin time compared to untreated plasma controls. Fibrin and D-Dimer formation were drastically decreased. The extracts and marrubiin concentration-dependently inhibited calcium mobilization induced by collagen and thrombin. The formation of thromboxane A2 was also significantly reduced by both the extracts and marrubiin. Protein secretion and platelet adhesion were significantly reduced by both the extracts and marrubiin. The organic extract and marrubiin showed a more pronounced effect than the aqueous extracts in all the in vitro assays. The ex-vivo animal model confirmed the results obtained in vitro. Similar to the in vitro studies, activated partial thromboplastin time clotting time was prolonged by marrubiin and the number of aggregated platelets were significantly reduced relative to aspirin. The findings reflect that marrubiin largely contributes to the organic extract's anticoagulant and antiplatelet effect in vitro. INS-1 cells were cultured under normo- and hyperglycaemic conditions. Marrubiin and the two Leonotis leonurus extracts were screened for anti-diabetic activity in vitro. The stimulatory index of INS-1 cells cultured under hyperglycaemic conditions was significantly increased by 60 percent and 61 percent (p<0.01; n=5) in cells exposed to the organic extract (10 μg/mL) and marrubiin (500 ng/mL), respectively, relative to the normoglycaemic conditions. The gene expression of insulin was significantly increased by 76.5 and 71 percent, and of glucose transporter-2 by 93 and 92.5 percent for marrubiin and the organic extract, respectively, under the same conditions stipulated above (p<0.01; n=4). The extract and marrubiin similarly showed an increase in respiratory rate under hyperglycaemic conditions. Marrubiin increased insulin secretion, HDL-cholesterol, while it decreased total cholesterol, LDL-cholesterol and the atherogenic index in the in vivo rat model.
- Full Text:
- Date Issued: 2010
Exploring and expanding learning processes in sustainable agriculture workplace contexts
- Authors: Mukute, Mutizwa
- Date: 2010
- Subjects: Sustainable agriculture -- Africa, Southern Sustainable development -- Study and teaching -- Africa, Southern Permaculture -- Zimbabwe Organic farming -- South Africa Farmers -- Social conditions -- Africa, Southern Farmers -- Economic conditions -- Africa, Southern Farmers -- Training of -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1539 , http://hdl.handle.net/10962/d1003421
- Description: The focus of this study is to explore and expand farmer learning processes in sustainable agriculture workplace contexts. It examines change oriented learning processes in the context of three sustainable agriculture practices. The study begins by discussing the history and emergence of environmental discourses and approaches; sustainable agriculture; and the histories of three kinds of sustainable agriculture practices: Permaculture, Organic Farming and Machobane Farming System. It also traces the evolution of agricultural extension approaches within the wider context of education for sustainable development. The main focus of the study is an exploration of how farmer learning can be mediated through an expansive learning process. The study methodology surfaces some of the contradictions in sustainable agriculture and learning activity systems that farmers encounter in learning and practising sustainable agriculture. It uses these contradictions as sources of expansive learning in and between the respective activity systems of farmers, sustainable agriculture facilitators, agricultural extension workers (conventional) and organic entrepreneurs. As shown in the study, the expansive learning processes result in the modelling, implementation and reviewing of solutions to contradictions being faced in the learning and practice of sustainable agriculture. The study also proposes a number of tools that can be adapted and used by development farmers and agricultural trainers to examine and expand learning as well as build farmer agency. The study was conducted in three case study sites in Lesotho, South Africa and Zimbabwe. In Zimbabwe the study is located in Hwedza district in the St Margaret Primary School and community that learn, practise and facilitate the learning of Permaculture within the Schools and Colleges Permaculture Programme (SCOPE). The second study site is in South Africa: Durban urban and peri-urban areas where a community of organic farmers, facilitators and entrepreneurs coordinate the marketing of their produce through Isidore Farm and Earth Mother Organic and support each other to learn and practise organic farming. The third study site is based in the Mafeteng and Mohale‟s Hoek districts of Lesotho where the focus was on farmers who learn and practise the Machobane Farming System (MFS) and are supported in this by the Rural Self Development Association (RSDA) and the Machobane Agricultural Development Foundation (MADF). Drawing on three sensitising concepts of dialectics, reflexivity and agency, the study worked with Cultural Historical Activity Theory (CHAT) underpinned by critical realism to reveal how farmer learning is mediated and expanded. The theory of practice/habitus also provided a useful theoretical lens with which to examine data generated. Using a two-phased, multiple embedded case study approach, the study worked within the broad framework of social learning. It used semi-structured individual and group interviews, observations and document analysis to explore learning processes and generate „mirror‟ data. This data was then used in Change Laboratory Workshops, within the Developmental Work Research methodology, where double stimulation and focus group discussions contributed to expanding learning processes. Drawing on critical realism the study used inductive, abductive and retroductive modes of inference to analyse data in each case study as well as across case studies. The findings of the study reveal that farmer learning is influenced by both intrinsic motives, such as identity, and extrinsic motives which are primarily associated with economic, ecological and health benefits. Farmers learn through scaffolding and mediating tools that link everyday and scientific knowledge. They also learn from fellow farmers through observation, practising and experimentation. Some of the issues that were raised in connection with farmer learning processes are: language; time to learn, practice and appropriate concepts; time to improve the natural resource base while at the same time improving income generation; and responses to climate change. The study also found that farmer learning and practice of sustainable agriculture in the case studies investigated, is influenced by past and current agricultural and educational policies; societal values and attitudes; social and cultural backgrounds; work affordances and gender relations; quality of training offered; poverty; and, HIV and AIDS. In the second phase of the study, which built on the problematic situations being encountered by research participants (sustainable agriculture farmers, sustainable agriculture facilitators, extension workers, and organic marketers) to surface contradictions, the main finding was that the expansive learning process has potential to enhance farmer learning and practice of sustainable agriculture. It does this by mobilising distributed cognition among participants as well as their preparedness to act. Through the expansive learning processes in each case study, research participants were able to question their practices, surface contradictions, model solutions and implement them, and thus build individual, collective and relational agency reflexively. Observation of this required micro-analysis of agentive talk and reflective talk. The study contributes in-depth insight into participatory research and learning processes, especially within the context of people-centred learning and innovation in the agricultural development arena. It provides empirical and explanatory insight into how change oriented social learning can emerge and be expanded in Education for Sustainable Development, explaining learning and change relationships in three sustainable agricultural practices. It also provides learning and extension tools to work with contradictions that arise from intentionality, experience, context and history in farming and training activity systems. Its key contribution lies in providing in-depth insight into mobilisation of human agency and reflexivity in change oriented sustainable agriculture learning and development, processes that are critical for responding to contemporary socio-ecological issues and risks.
- Full Text:
- Date Issued: 2010
- Authors: Mukute, Mutizwa
- Date: 2010
- Subjects: Sustainable agriculture -- Africa, Southern Sustainable development -- Study and teaching -- Africa, Southern Permaculture -- Zimbabwe Organic farming -- South Africa Farmers -- Social conditions -- Africa, Southern Farmers -- Economic conditions -- Africa, Southern Farmers -- Training of -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1539 , http://hdl.handle.net/10962/d1003421
- Description: The focus of this study is to explore and expand farmer learning processes in sustainable agriculture workplace contexts. It examines change oriented learning processes in the context of three sustainable agriculture practices. The study begins by discussing the history and emergence of environmental discourses and approaches; sustainable agriculture; and the histories of three kinds of sustainable agriculture practices: Permaculture, Organic Farming and Machobane Farming System. It also traces the evolution of agricultural extension approaches within the wider context of education for sustainable development. The main focus of the study is an exploration of how farmer learning can be mediated through an expansive learning process. The study methodology surfaces some of the contradictions in sustainable agriculture and learning activity systems that farmers encounter in learning and practising sustainable agriculture. It uses these contradictions as sources of expansive learning in and between the respective activity systems of farmers, sustainable agriculture facilitators, agricultural extension workers (conventional) and organic entrepreneurs. As shown in the study, the expansive learning processes result in the modelling, implementation and reviewing of solutions to contradictions being faced in the learning and practice of sustainable agriculture. The study also proposes a number of tools that can be adapted and used by development farmers and agricultural trainers to examine and expand learning as well as build farmer agency. The study was conducted in three case study sites in Lesotho, South Africa and Zimbabwe. In Zimbabwe the study is located in Hwedza district in the St Margaret Primary School and community that learn, practise and facilitate the learning of Permaculture within the Schools and Colleges Permaculture Programme (SCOPE). The second study site is in South Africa: Durban urban and peri-urban areas where a community of organic farmers, facilitators and entrepreneurs coordinate the marketing of their produce through Isidore Farm and Earth Mother Organic and support each other to learn and practise organic farming. The third study site is based in the Mafeteng and Mohale‟s Hoek districts of Lesotho where the focus was on farmers who learn and practise the Machobane Farming System (MFS) and are supported in this by the Rural Self Development Association (RSDA) and the Machobane Agricultural Development Foundation (MADF). Drawing on three sensitising concepts of dialectics, reflexivity and agency, the study worked with Cultural Historical Activity Theory (CHAT) underpinned by critical realism to reveal how farmer learning is mediated and expanded. The theory of practice/habitus also provided a useful theoretical lens with which to examine data generated. Using a two-phased, multiple embedded case study approach, the study worked within the broad framework of social learning. It used semi-structured individual and group interviews, observations and document analysis to explore learning processes and generate „mirror‟ data. This data was then used in Change Laboratory Workshops, within the Developmental Work Research methodology, where double stimulation and focus group discussions contributed to expanding learning processes. Drawing on critical realism the study used inductive, abductive and retroductive modes of inference to analyse data in each case study as well as across case studies. The findings of the study reveal that farmer learning is influenced by both intrinsic motives, such as identity, and extrinsic motives which are primarily associated with economic, ecological and health benefits. Farmers learn through scaffolding and mediating tools that link everyday and scientific knowledge. They also learn from fellow farmers through observation, practising and experimentation. Some of the issues that were raised in connection with farmer learning processes are: language; time to learn, practice and appropriate concepts; time to improve the natural resource base while at the same time improving income generation; and responses to climate change. The study also found that farmer learning and practice of sustainable agriculture in the case studies investigated, is influenced by past and current agricultural and educational policies; societal values and attitudes; social and cultural backgrounds; work affordances and gender relations; quality of training offered; poverty; and, HIV and AIDS. In the second phase of the study, which built on the problematic situations being encountered by research participants (sustainable agriculture farmers, sustainable agriculture facilitators, extension workers, and organic marketers) to surface contradictions, the main finding was that the expansive learning process has potential to enhance farmer learning and practice of sustainable agriculture. It does this by mobilising distributed cognition among participants as well as their preparedness to act. Through the expansive learning processes in each case study, research participants were able to question their practices, surface contradictions, model solutions and implement them, and thus build individual, collective and relational agency reflexively. Observation of this required micro-analysis of agentive talk and reflective talk. The study contributes in-depth insight into participatory research and learning processes, especially within the context of people-centred learning and innovation in the agricultural development arena. It provides empirical and explanatory insight into how change oriented social learning can emerge and be expanded in Education for Sustainable Development, explaining learning and change relationships in three sustainable agricultural practices. It also provides learning and extension tools to work with contradictions that arise from intentionality, experience, context and history in farming and training activity systems. Its key contribution lies in providing in-depth insight into mobilisation of human agency and reflexivity in change oriented sustainable agriculture learning and development, processes that are critical for responding to contemporary socio-ecological issues and risks.
- Full Text:
- Date Issued: 2010
An analysis of emerging forms of social organisation and agency in the aftermath of 'fast track' land reform in Zimbabwe
- Authors: Murisa, Tendai
- Date: 2010
- Subjects: Land reform -- Zimbabwe Right of property -- Zimbabwe Zimbabwe -- Economic conditions Zimbabwe -- Social conditions -- 1980- Zimbabwe -- Politics and government -- 1980- Zimbabwe -- Social life and customs Land settlement -- Social aspects -- Zimbabwe Group identity -- Zimbabwe Social change -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3293 , http://hdl.handle.net/10962/d1003081
- Description: The fast track land reform programme resulted in a fundamental reorganisation of rural relations in Zimbabwe, changing the landscape in an irreversible way with people from diverse backgrounds converging on former white-owned farms. This thesis tells the story of how the newly resettled land beneficiaries are organising themselves socially in response to various economic challenges. It makes a contribution towards understanding how redistributive land reforms and local government restructuring influence rural social organisation and agency. Furthermore the study examines local perceptions on the meanings of the „farm‟ and „land redistribution‟. An utterance by one war veteran “what used to be your farm is now our land and you are free to take your farm but leave our land” provides an alternative rendition to contestations of restitution versus a purely farm productionist discourse. The study, through an analysis of primary and secondary data, provides a fresh understanding of the social outcomes of fast track. It traces the evolution of land and agrarian reforms in post-independence Zimbabwe and the political and social economic context that led to „fast track‟. Through an analysis of field findings the thesis is able to define the dominant social groups that were resettled during fast track and the challenges they face in utilising the land. The findings show that the majority of the land beneficiaries were from the customary areas, with limited agricultural experiences. Local cooperation within informal networks and local farmer groups has been identified as one of the ways in which social reproduction is being organised. These groups are responsible for enhancing production capacity but they face a number of constraints. The study derives its theoretical foundation from the post 1980s debates on rural society dominated by Mafeje (1993, 2003), Rahmato (1991) and Mamdani (1996). The debates centred on how institutions of inclusion, authority and cooperation such as the lineage groups, local farmer groups and traditional authority remain relevant in the organisation of post-independent rural African society especially in a context of increased commoditisation of rural relations of production. Using theoretical insights derived from analysing the role of the lineage groups in the allocation of critical resources such as land and the influence of traditional authority (indirect rule) as a form of local government, the study examines how social organisation is emerging in areas where neither lineage nor traditional authority are not dominant. The thesis of rural cooperation through local groups as advanced by Rahmato (1991) and Moyo (2002) provides partial insights into the response mechanisms that land beneficiaries invoke in this instance. It is not necessarily an autonomous space of organisation but rather the state is actively involved through various functionaries including extension officers who invariably advance a very productionist approach. The state‟s monopoly through its local functionaries hides its political cooptation effect by emphasising organisation for production without questioning the manner in which that production is externally controlled through limited rights over land, the state‟s monopoly over inputs supply and markets for commodities. Whilst land reform has been driven by local participation through land occupations, local government reform has been technocratically determined through Ministerial directives. There is however little innovation in the form of local government that is being introduced. It expands the fusion of authority between elected Rural District Councils and unelected traditional authority functionaries. The forms of social organisation and agency that have emerged remain subordinated to the state with no links to other networks of rural producers‟ associations and urban civil society organisations. These developments form part of a longheld tradition within the Zimbabwean state where the legitimacy of local organisation and authority is usurped to service the interests of the state. Thus whilst land reform has to a certain extent accommodated the majority poor, the ensuing local government and agrarian reforms are more focused on limiting their participation in broader processes of political engagement around distribution and accumulation and their own governance.
- Full Text:
- Date Issued: 2010
- Authors: Murisa, Tendai
- Date: 2010
- Subjects: Land reform -- Zimbabwe Right of property -- Zimbabwe Zimbabwe -- Economic conditions Zimbabwe -- Social conditions -- 1980- Zimbabwe -- Politics and government -- 1980- Zimbabwe -- Social life and customs Land settlement -- Social aspects -- Zimbabwe Group identity -- Zimbabwe Social change -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3293 , http://hdl.handle.net/10962/d1003081
- Description: The fast track land reform programme resulted in a fundamental reorganisation of rural relations in Zimbabwe, changing the landscape in an irreversible way with people from diverse backgrounds converging on former white-owned farms. This thesis tells the story of how the newly resettled land beneficiaries are organising themselves socially in response to various economic challenges. It makes a contribution towards understanding how redistributive land reforms and local government restructuring influence rural social organisation and agency. Furthermore the study examines local perceptions on the meanings of the „farm‟ and „land redistribution‟. An utterance by one war veteran “what used to be your farm is now our land and you are free to take your farm but leave our land” provides an alternative rendition to contestations of restitution versus a purely farm productionist discourse. The study, through an analysis of primary and secondary data, provides a fresh understanding of the social outcomes of fast track. It traces the evolution of land and agrarian reforms in post-independence Zimbabwe and the political and social economic context that led to „fast track‟. Through an analysis of field findings the thesis is able to define the dominant social groups that were resettled during fast track and the challenges they face in utilising the land. The findings show that the majority of the land beneficiaries were from the customary areas, with limited agricultural experiences. Local cooperation within informal networks and local farmer groups has been identified as one of the ways in which social reproduction is being organised. These groups are responsible for enhancing production capacity but they face a number of constraints. The study derives its theoretical foundation from the post 1980s debates on rural society dominated by Mafeje (1993, 2003), Rahmato (1991) and Mamdani (1996). The debates centred on how institutions of inclusion, authority and cooperation such as the lineage groups, local farmer groups and traditional authority remain relevant in the organisation of post-independent rural African society especially in a context of increased commoditisation of rural relations of production. Using theoretical insights derived from analysing the role of the lineage groups in the allocation of critical resources such as land and the influence of traditional authority (indirect rule) as a form of local government, the study examines how social organisation is emerging in areas where neither lineage nor traditional authority are not dominant. The thesis of rural cooperation through local groups as advanced by Rahmato (1991) and Moyo (2002) provides partial insights into the response mechanisms that land beneficiaries invoke in this instance. It is not necessarily an autonomous space of organisation but rather the state is actively involved through various functionaries including extension officers who invariably advance a very productionist approach. The state‟s monopoly through its local functionaries hides its political cooptation effect by emphasising organisation for production without questioning the manner in which that production is externally controlled through limited rights over land, the state‟s monopoly over inputs supply and markets for commodities. Whilst land reform has been driven by local participation through land occupations, local government reform has been technocratically determined through Ministerial directives. There is however little innovation in the form of local government that is being introduced. It expands the fusion of authority between elected Rural District Councils and unelected traditional authority functionaries. The forms of social organisation and agency that have emerged remain subordinated to the state with no links to other networks of rural producers‟ associations and urban civil society organisations. These developments form part of a longheld tradition within the Zimbabwean state where the legitimacy of local organisation and authority is usurped to service the interests of the state. Thus whilst land reform has to a certain extent accommodated the majority poor, the ensuing local government and agrarian reforms are more focused on limiting their participation in broader processes of political engagement around distribution and accumulation and their own governance.
- Full Text:
- Date Issued: 2010
The biotechnology of hard coal utilization as a bioprocess substrate
- Mutambanengwe, Cecil Clifford Zvandada
- Authors: Mutambanengwe, Cecil Clifford Zvandada
- Date: 2010
- Subjects: Coal -- Biotechnology Acid mine drainage Coal mines and mining -- Environmental aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3934 , http://hdl.handle.net/10962/d1003993
- Description: The development of coal biotechnology, using hard coal as a substrate, has been impeded by its low reactivity in biological processes. As a result, the more successful application studies have focused on lignitic soft coals. However, new studies have reported using biologically or geologically oxidized hard coal as a functional substrate option for bioprocess applications on a large scale. This study undertook a preliminary investigation into the feasibility of environmental applications of coal biotechnology using oxidized hard coal substrates in both anaerobic and aerobic processes with carbon dioxide, sulfate and oxygen as terminal electron acceptors. A preliminary characterization of the oxidized hard coal substrates was undertaken to determine and predict their viability and behavior as electron donors and carbon sources for environmental bioprocess applications of direct interest to the coal mining industry. Both biologically and geologically oxidized coal substrates showed loss of up to 17% and 52% carbon respectively and incorporation of oxygen ranging from 0.9 – 24%. The latter substrate showed greater loss of carbon and increased oxygenation. The biologically and geologically oxidized hard coal substrates were shown to partition readily into 23% and 32% organic humic acid, a 0.1% fulvic acid fraction and 65% and 59% inorganic and humin fractions respectively. These organic components were shown to be potentially available for biological consumption. In the unmodified hard coal substrate, partitioning was not observed and it did not perform as a functional substrate for any of the bioprocesses investigated. Where carbon dioxide was used as a terminal electron acceptor, methane production ranging from 9 – 26 mg CH4.g substrate-1 was demonstrated from both oxidized coal substrates. Geologically oxidized coal produced 30% more methane than biologically oxidized coal. Methane yields from the geologically oxidized coal in the presence and absence of a co-substrate were 5 – 13-fold higher than previous studies that used hard coal for methanogenesis. Based on these results, and that the development and optimization of the biological oxidation process is currently ongoing, further applications investigated in this study were undertaken using geologically oxidized coal. It was shown using pyrolysis gas chromatography mass spectrometry that the methanogenic system was dependent on the presence of an effective co-substrate supporting the breakdown of the complex organic structures within the oxidized hard coal substrate. Also that the accumulation of aromatic intermediate breakdown compounds predominantly including toluene, furfural, styrene and 2-methoxy vinyl phenol appeared to become inhibitory to both methanogenic and sulfidogenic reactions. This was shown to be a more likely cause of reactor failure rather than substrate exhaustion over time. Evidence of a reductive degradation pathway of the complex organic structures within the oxidized hard coal substrates was shown through the production, accumulation and utilization of volatile fatty acids including acetic, formic, propionic, butyric and valeric acids. Comparative analysis of the volatile fatty acids produced in this system showed that geologically oxidized coal produced 20% more of the volatile fatty acids profiled and double the total concentration compared to the biologically oxidized coal. The use of geologically oxidized hard coal as a functional substrate for biological sulfate reduction was demonstrated in the neutralization of a simulated acid mine drainage wastewater in both batch and continuous process operations. Results showed an increase in pH from pH 4.0 to ~ pH 8.0 with sulfide production rates of ~ 86 mgL-1.day-1 in the batch reactions, while the pH increased to pH 9.0 and sulfide production rates of up to 450 mgL-1.day-1 were measured in the continuous process studies using sand and coal up-flow packed bed reactors. Again, the requirement for an effective co-substrate was demonstrated with lactate shown to function as a true co-substrate in this system. However, a low cost alternative to lactate would need to emerge if the process was to function in large-scale commercial environmental treatment applications. In this regard, the aerobic growth and production of Neosartorya fischeri biomass (0.64 g.biomass.g SOC-1) was demonstrated using oxidized hard coal and glutamate as a co-substrate. Both can be produced from wastes generated on coal mines, with the fungal biomass generated in potentially large volumes. Preliminary demonstration of the use of the fungal biomass as a carbon and electron donor source for biological sulfate reduction was shown and thus that this could serve as an effective substrate for anaerobic environmental treatment processes. Based on these findings, an Integrated Coal Bioprocess model was proposed using oxidized hard coal as a substrate for environmental remediation applications on coal mines. In this approach, potential applications included methane recovery from waste coal, use of waste coal in the treatment of acid mine drainage waste waters and the recovery and use of humic acids in the rehabilitation of open cast mining soils. This study provided a first report demonstrating the use of biologically and geologically oxidized hard coals as bioprocess substrates in environmental bioremediation applications. It also provided an indication that follow-up bioengineering studies to investigate scaled-up applications of these findings would be warranted.
- Full Text:
- Date Issued: 2010
- Authors: Mutambanengwe, Cecil Clifford Zvandada
- Date: 2010
- Subjects: Coal -- Biotechnology Acid mine drainage Coal mines and mining -- Environmental aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3934 , http://hdl.handle.net/10962/d1003993
- Description: The development of coal biotechnology, using hard coal as a substrate, has been impeded by its low reactivity in biological processes. As a result, the more successful application studies have focused on lignitic soft coals. However, new studies have reported using biologically or geologically oxidized hard coal as a functional substrate option for bioprocess applications on a large scale. This study undertook a preliminary investigation into the feasibility of environmental applications of coal biotechnology using oxidized hard coal substrates in both anaerobic and aerobic processes with carbon dioxide, sulfate and oxygen as terminal electron acceptors. A preliminary characterization of the oxidized hard coal substrates was undertaken to determine and predict their viability and behavior as electron donors and carbon sources for environmental bioprocess applications of direct interest to the coal mining industry. Both biologically and geologically oxidized coal substrates showed loss of up to 17% and 52% carbon respectively and incorporation of oxygen ranging from 0.9 – 24%. The latter substrate showed greater loss of carbon and increased oxygenation. The biologically and geologically oxidized hard coal substrates were shown to partition readily into 23% and 32% organic humic acid, a 0.1% fulvic acid fraction and 65% and 59% inorganic and humin fractions respectively. These organic components were shown to be potentially available for biological consumption. In the unmodified hard coal substrate, partitioning was not observed and it did not perform as a functional substrate for any of the bioprocesses investigated. Where carbon dioxide was used as a terminal electron acceptor, methane production ranging from 9 – 26 mg CH4.g substrate-1 was demonstrated from both oxidized coal substrates. Geologically oxidized coal produced 30% more methane than biologically oxidized coal. Methane yields from the geologically oxidized coal in the presence and absence of a co-substrate were 5 – 13-fold higher than previous studies that used hard coal for methanogenesis. Based on these results, and that the development and optimization of the biological oxidation process is currently ongoing, further applications investigated in this study were undertaken using geologically oxidized coal. It was shown using pyrolysis gas chromatography mass spectrometry that the methanogenic system was dependent on the presence of an effective co-substrate supporting the breakdown of the complex organic structures within the oxidized hard coal substrate. Also that the accumulation of aromatic intermediate breakdown compounds predominantly including toluene, furfural, styrene and 2-methoxy vinyl phenol appeared to become inhibitory to both methanogenic and sulfidogenic reactions. This was shown to be a more likely cause of reactor failure rather than substrate exhaustion over time. Evidence of a reductive degradation pathway of the complex organic structures within the oxidized hard coal substrates was shown through the production, accumulation and utilization of volatile fatty acids including acetic, formic, propionic, butyric and valeric acids. Comparative analysis of the volatile fatty acids produced in this system showed that geologically oxidized coal produced 20% more of the volatile fatty acids profiled and double the total concentration compared to the biologically oxidized coal. The use of geologically oxidized hard coal as a functional substrate for biological sulfate reduction was demonstrated in the neutralization of a simulated acid mine drainage wastewater in both batch and continuous process operations. Results showed an increase in pH from pH 4.0 to ~ pH 8.0 with sulfide production rates of ~ 86 mgL-1.day-1 in the batch reactions, while the pH increased to pH 9.0 and sulfide production rates of up to 450 mgL-1.day-1 were measured in the continuous process studies using sand and coal up-flow packed bed reactors. Again, the requirement for an effective co-substrate was demonstrated with lactate shown to function as a true co-substrate in this system. However, a low cost alternative to lactate would need to emerge if the process was to function in large-scale commercial environmental treatment applications. In this regard, the aerobic growth and production of Neosartorya fischeri biomass (0.64 g.biomass.g SOC-1) was demonstrated using oxidized hard coal and glutamate as a co-substrate. Both can be produced from wastes generated on coal mines, with the fungal biomass generated in potentially large volumes. Preliminary demonstration of the use of the fungal biomass as a carbon and electron donor source for biological sulfate reduction was shown and thus that this could serve as an effective substrate for anaerobic environmental treatment processes. Based on these findings, an Integrated Coal Bioprocess model was proposed using oxidized hard coal as a substrate for environmental remediation applications on coal mines. In this approach, potential applications included methane recovery from waste coal, use of waste coal in the treatment of acid mine drainage waste waters and the recovery and use of humic acids in the rehabilitation of open cast mining soils. This study provided a first report demonstrating the use of biologically and geologically oxidized hard coals as bioprocess substrates in environmental bioremediation applications. It also provided an indication that follow-up bioengineering studies to investigate scaled-up applications of these findings would be warranted.
- Full Text:
- Date Issued: 2010
Isomorphism, institutional entrepreneurship and total quality management (TQM) : a case study in the implementation of quality management standards and excellence models in South African developmental local government
- Authors: Naidoo, Pravine
- Date: 2010
- Subjects: Local government -- South Africa -- Eastern Cape Political entrepreneurship -- South Africa -- Eastern Cape Total quality management Municipal services -- South Africa -- Eastern Cape -- Management Municipal services -- Customer services -- South Africa -- Eastern Cape Political leadership -- South Africa -- Eastern Cape Organizational effectiveness
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1193 , http://hdl.handle.net/10962/d1007141
- Description: Within the new constitutional order, South African local government has been afforded specific status and is protected as a distinctive sphere of government in terms of the Constitution Act 108 of 1996. Municipalities are no longer a mere function of national or provincial governments. In addition to this entrenched status, the Constitution and other developmental local government legislation vests local government with specific functions and responsibilities as part of the process of building a new democracy and promoting socio-economic development and upliftment. Consequently, local government managers are under constant pressure to improve the performance and quality of service delivery. They are expected to satisfy a number of stakeholders, achieve increases in efficiency, as well as attain developmental service delivery goals as contained in their Integrated Development Plan (IDP). Quality management standards and excellence models in support of the total quality management (TQM) philosophy are relatively new public management approaches that changes traditional organisational decision-making practices to deliver services to its customers in more effective and efficient ways. In essence, quality management standards and excellence models are performance management methodological practices, techniques and tools designed to meet and exceed public requirements. It accomplishes this through determining what constitutes excellence in customer service, and then empowering employees to a never-ending search for quality improvement in the delivery of services, in terms of the continuous improvement and continuous process improvement philosophies, of which total quality management (TQM) is premised on. Consequently, quality management standards and excellence models (such as the ISO 9001: 2008 QMS, ISO 14001: 2004 EMS, EFQM and SAEF Excellence Models) as methodological practices, techniques or tools in support of the critical factors (CFs) of the total quality management (TQM) philosophy, namely: (1) customer-based approach, (2) senior management commitment and leadership, (3) quality planning, (4) management based on facts, (5) continuous improvement, (6) involvement of all members of the organisation, (7) education and training, (8) teamwork, (9) communication systems, (10) learning, (11) process management, (12) co-operation with suppliers, and (13) organisational awareness and concern for the social and environmental context, can provide a framework by which to achieve the goals of effective and efficient service delivery in developmental local government, as they foster a culture of performance and accountability. Local government managers could use these quality and excellence methodological practices, techniques and tools, as a starting point to improve efficiencies in their municipalities, as the programmes afford them an opportunity to systematically evaluate the municipality and determine what leads to organisational success and deliverables. Institutional theory suggests that organisations are both influenced by and can influence the society in which they operate. Institutional theorists believe that the motivation for a change in internal practices might not only be performance related, but may primarily be to enhance or maintain the legitimacy of the respective institution. Institutional theory also focuses on the social contract that exists between the institution and society. This social contract is believed to represent the expectations of society. From an institutional point of view, it has been suggested that institutions may change and adopt the norms of society to appear legitimate to that society. This infers that when societal norms and values change, institutions will be expected to change. These societal pressures combined with legislative changes, require institutional entrepreneurs to respond to these isomorphic pressures, and will work to preserve the institution's legitimacy by incorporating, or at least appearing to incorporate, new practices, norms and values. The aim of this research study was to analyse within an institutional theory framework, the implementation of quality management standards and excellence models in support of the total quality management (TQM) philosophy and developmental local government within two South African municipalities. The research investigation has been undertaken within the social constructionist paradigm and using the case study method. Interviews and documents were the data sources and thematic analysis was used as a tool to analyse the data by applying a theory-driven coding procedure. The findings from the two research sites, namely Makana Municipality in Grahamstown and Drakenstein Municipality in Paarl reveal that the implementation of quality management standards and excellence models in support of the total quality management (TQM) philosophy in both municipalities was not a smooth process and there were many challenges such as political instability, lack of commitment on the part of the senior leadership and management, staff and skills shortages, resistance by staff to implementation and resource constraints. Institutional theory has proved to be useful in understanding why the Makana and Drakenstein Municipalities implemented quality management standards and excellence models. Because of coercive, mimetic and normative isomorphic pressures affecting the Makana and Drakenstein municipalities, change was imperative if these institutions were to remain relevant and legitimate in order to address its service delivery mandate of effectiveness and efficiency. Institutional theory provided a theoretical lens to understand and appreciate the pressures that affected the municipalities because of its new developmental mandate as encapsulated in new municipal legislation. It also assisted in understanding how institutional entrepreneurs responded to these pressures to conform. The implementation of quality management standards and excellence models in the Makana and Drakenstein municipalities was adversely affected by volatility amongst the political leadership of both municipalities. The successful implementation of these standards and models would require collective action from the political, bureaucratic and procedural entrepreneurs in order to enhance effective, efficient and accountable service delivery. However, in both the Makana and Drakenstein municipalities, institutional entrepreneurs, namely councillors and officials were not working together as a collective to implement quality management standards and excellence models. Evidence has shown that the absence of stable political leadership and noncooperation and collaboration amongst institutional entrepreneurs contributed significantly to the non-institutionalisation of quality management standards and excellence models in these Municipalities. This implies that legitimacy has not been achieved, due to institutional entrepreneurs not collaborating and collectively working with each other to implement the quality management standards and excellence models. Thus, this research study suggests that the strategic and collective role of the political and administrative leadership as institutional entrepreneurs is critical if the municipality is to achieve its aims and objectives, namely effective, efficient, and accountable service delivery in developmental local government. Recommendations in respect of future research and to practitioners have also been offered.
- Full Text:
- Date Issued: 2010
- Authors: Naidoo, Pravine
- Date: 2010
- Subjects: Local government -- South Africa -- Eastern Cape Political entrepreneurship -- South Africa -- Eastern Cape Total quality management Municipal services -- South Africa -- Eastern Cape -- Management Municipal services -- Customer services -- South Africa -- Eastern Cape Political leadership -- South Africa -- Eastern Cape Organizational effectiveness
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1193 , http://hdl.handle.net/10962/d1007141
- Description: Within the new constitutional order, South African local government has been afforded specific status and is protected as a distinctive sphere of government in terms of the Constitution Act 108 of 1996. Municipalities are no longer a mere function of national or provincial governments. In addition to this entrenched status, the Constitution and other developmental local government legislation vests local government with specific functions and responsibilities as part of the process of building a new democracy and promoting socio-economic development and upliftment. Consequently, local government managers are under constant pressure to improve the performance and quality of service delivery. They are expected to satisfy a number of stakeholders, achieve increases in efficiency, as well as attain developmental service delivery goals as contained in their Integrated Development Plan (IDP). Quality management standards and excellence models in support of the total quality management (TQM) philosophy are relatively new public management approaches that changes traditional organisational decision-making practices to deliver services to its customers in more effective and efficient ways. In essence, quality management standards and excellence models are performance management methodological practices, techniques and tools designed to meet and exceed public requirements. It accomplishes this through determining what constitutes excellence in customer service, and then empowering employees to a never-ending search for quality improvement in the delivery of services, in terms of the continuous improvement and continuous process improvement philosophies, of which total quality management (TQM) is premised on. Consequently, quality management standards and excellence models (such as the ISO 9001: 2008 QMS, ISO 14001: 2004 EMS, EFQM and SAEF Excellence Models) as methodological practices, techniques or tools in support of the critical factors (CFs) of the total quality management (TQM) philosophy, namely: (1) customer-based approach, (2) senior management commitment and leadership, (3) quality planning, (4) management based on facts, (5) continuous improvement, (6) involvement of all members of the organisation, (7) education and training, (8) teamwork, (9) communication systems, (10) learning, (11) process management, (12) co-operation with suppliers, and (13) organisational awareness and concern for the social and environmental context, can provide a framework by which to achieve the goals of effective and efficient service delivery in developmental local government, as they foster a culture of performance and accountability. Local government managers could use these quality and excellence methodological practices, techniques and tools, as a starting point to improve efficiencies in their municipalities, as the programmes afford them an opportunity to systematically evaluate the municipality and determine what leads to organisational success and deliverables. Institutional theory suggests that organisations are both influenced by and can influence the society in which they operate. Institutional theorists believe that the motivation for a change in internal practices might not only be performance related, but may primarily be to enhance or maintain the legitimacy of the respective institution. Institutional theory also focuses on the social contract that exists between the institution and society. This social contract is believed to represent the expectations of society. From an institutional point of view, it has been suggested that institutions may change and adopt the norms of society to appear legitimate to that society. This infers that when societal norms and values change, institutions will be expected to change. These societal pressures combined with legislative changes, require institutional entrepreneurs to respond to these isomorphic pressures, and will work to preserve the institution's legitimacy by incorporating, or at least appearing to incorporate, new practices, norms and values. The aim of this research study was to analyse within an institutional theory framework, the implementation of quality management standards and excellence models in support of the total quality management (TQM) philosophy and developmental local government within two South African municipalities. The research investigation has been undertaken within the social constructionist paradigm and using the case study method. Interviews and documents were the data sources and thematic analysis was used as a tool to analyse the data by applying a theory-driven coding procedure. The findings from the two research sites, namely Makana Municipality in Grahamstown and Drakenstein Municipality in Paarl reveal that the implementation of quality management standards and excellence models in support of the total quality management (TQM) philosophy in both municipalities was not a smooth process and there were many challenges such as political instability, lack of commitment on the part of the senior leadership and management, staff and skills shortages, resistance by staff to implementation and resource constraints. Institutional theory has proved to be useful in understanding why the Makana and Drakenstein Municipalities implemented quality management standards and excellence models. Because of coercive, mimetic and normative isomorphic pressures affecting the Makana and Drakenstein municipalities, change was imperative if these institutions were to remain relevant and legitimate in order to address its service delivery mandate of effectiveness and efficiency. Institutional theory provided a theoretical lens to understand and appreciate the pressures that affected the municipalities because of its new developmental mandate as encapsulated in new municipal legislation. It also assisted in understanding how institutional entrepreneurs responded to these pressures to conform. The implementation of quality management standards and excellence models in the Makana and Drakenstein municipalities was adversely affected by volatility amongst the political leadership of both municipalities. The successful implementation of these standards and models would require collective action from the political, bureaucratic and procedural entrepreneurs in order to enhance effective, efficient and accountable service delivery. However, in both the Makana and Drakenstein municipalities, institutional entrepreneurs, namely councillors and officials were not working together as a collective to implement quality management standards and excellence models. Evidence has shown that the absence of stable political leadership and noncooperation and collaboration amongst institutional entrepreneurs contributed significantly to the non-institutionalisation of quality management standards and excellence models in these Municipalities. This implies that legitimacy has not been achieved, due to institutional entrepreneurs not collaborating and collectively working with each other to implement the quality management standards and excellence models. Thus, this research study suggests that the strategic and collective role of the political and administrative leadership as institutional entrepreneurs is critical if the municipality is to achieve its aims and objectives, namely effective, efficient, and accountable service delivery in developmental local government. Recommendations in respect of future research and to practitioners have also been offered.
- Full Text:
- Date Issued: 2010
The integration of natural resource management into the curriculum of rural under-resourced schools : a Bernsteinian analysis
- Authors: Nsubuga, Yvonne Nakalo
- Date: 2010
- Subjects: Conservation of natural resources -- Study and teaching -- South Africa Environmental education -- Curricula -- South Africa -- Eastern Cape Bernstein, Basil B Nature conservation -- Study and teaching
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4762 , http://hdl.handle.net/10962/d1007157
- Description: This study was motivated by the need to improve curriculum relevance in poor rural schools through contextualised teaching and learning based on the management of local natural resources. It involved four schools which are located in the Ngqunshwa Local Municipality of the Eastern Cape Province of South Africa. The study's aim was to provide insight into and better understanding of the curriculum implementation process regarding natural resource management (NRM) education in a poor rural education context. This was done by analysing the extent of NRM integration in pedagogic texts, activities and practices in the different fields which constitute the structure of the pedagogic system in this education sector. The study adopted an interpretivist approach to the analysis, which was based on indicators of the extent of NRM integration, and was informed by Bernstein's concepts of classification and curriculum recontextualisation, and his model of the structure of the pedagogic system. The items which were analysed included national and provincial Grade 10 Life Sciences curriculum documents, Grade 10 Life Sciences textbooks, in-service training workshops for Life Sciences teachers, and various school documents, activities and practices. The analysis also involved interviews with educators, and classroom observations of Grade 10 Life Sciences lessons. The results revealed a very high overall level of NRM integration in the Grade 10 Life Sciences curriculum documents produced at national and provincial levels. The overall level of NRM integration was also found to be very high in the Grade 10 Life Science textbooks that were analysed, but very low in the in-service teacher training workshops, and in the schools' documents, activities and practices, especially in the Grade 10 Life Sciences lessons, and in schools' end-of-year Grade 10 Life Sciences examination papers. The study makes a number of recommendations towards effective integration of NRM into the curriculum of Eastern Cape's rural poor schools which include more specific and explicit reference to NRM in the official Grade 10 Life Sciences curriculum documents, the provision of environmental education courses to district education staff and Grade 10 Life Sciences teachers, the training of teachers in the classroom use of textbooks and other educational materials, and regular monitoring of teachers' work. The study also exposes important knowledge gaps which need urgent research attention in order to enhance NRM education in the poor rural schools of the Eastern Cape. These include analysing power and control relationships between the various agencies and agents that are involved with curriculum implementation in this education sector, and conducting investigation into the creation of specialist NRM knowledge and into the quality of NRM knowledge that is transmitted as pedagogic discourse in schools. This study contributes to the fields of rural education and environmental education in South Africa, and to the growing interest in the study of curriculum from a sociology of education perspective in the context of the country’s post-apartheid curriculum reforms.
- Full Text:
- Date Issued: 2010
- Authors: Nsubuga, Yvonne Nakalo
- Date: 2010
- Subjects: Conservation of natural resources -- Study and teaching -- South Africa Environmental education -- Curricula -- South Africa -- Eastern Cape Bernstein, Basil B Nature conservation -- Study and teaching
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4762 , http://hdl.handle.net/10962/d1007157
- Description: This study was motivated by the need to improve curriculum relevance in poor rural schools through contextualised teaching and learning based on the management of local natural resources. It involved four schools which are located in the Ngqunshwa Local Municipality of the Eastern Cape Province of South Africa. The study's aim was to provide insight into and better understanding of the curriculum implementation process regarding natural resource management (NRM) education in a poor rural education context. This was done by analysing the extent of NRM integration in pedagogic texts, activities and practices in the different fields which constitute the structure of the pedagogic system in this education sector. The study adopted an interpretivist approach to the analysis, which was based on indicators of the extent of NRM integration, and was informed by Bernstein's concepts of classification and curriculum recontextualisation, and his model of the structure of the pedagogic system. The items which were analysed included national and provincial Grade 10 Life Sciences curriculum documents, Grade 10 Life Sciences textbooks, in-service training workshops for Life Sciences teachers, and various school documents, activities and practices. The analysis also involved interviews with educators, and classroom observations of Grade 10 Life Sciences lessons. The results revealed a very high overall level of NRM integration in the Grade 10 Life Sciences curriculum documents produced at national and provincial levels. The overall level of NRM integration was also found to be very high in the Grade 10 Life Science textbooks that were analysed, but very low in the in-service teacher training workshops, and in the schools' documents, activities and practices, especially in the Grade 10 Life Sciences lessons, and in schools' end-of-year Grade 10 Life Sciences examination papers. The study makes a number of recommendations towards effective integration of NRM into the curriculum of Eastern Cape's rural poor schools which include more specific and explicit reference to NRM in the official Grade 10 Life Sciences curriculum documents, the provision of environmental education courses to district education staff and Grade 10 Life Sciences teachers, the training of teachers in the classroom use of textbooks and other educational materials, and regular monitoring of teachers' work. The study also exposes important knowledge gaps which need urgent research attention in order to enhance NRM education in the poor rural schools of the Eastern Cape. These include analysing power and control relationships between the various agencies and agents that are involved with curriculum implementation in this education sector, and conducting investigation into the creation of specialist NRM knowledge and into the quality of NRM knowledge that is transmitted as pedagogic discourse in schools. This study contributes to the fields of rural education and environmental education in South Africa, and to the growing interest in the study of curriculum from a sociology of education perspective in the context of the country’s post-apartheid curriculum reforms.
- Full Text:
- Date Issued: 2010
Prevalence of Listeria pathogens in effluents of some wastewater treatment facilities in the Eastern Cape Province of South Africa
- Odjadjare, Emmanuel Erufuare Onogwuwhenya
- Authors: Odjadjare, Emmanuel Erufuare Onogwuwhenya
- Date: 2010
- Subjects: Listeria -- South Africa -- Eastern Cape Sewage -- Purification -- South Africa -- Eastern Cape Water -- Pollution -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/7826 , vital:30747
- Description: astewater discharges may contain health compromising pathogens and carcinogenic and/or chemical substances that could compromise the public health and impact negatively on the environment. The present study was conducted between August 2007 and July 2008 to evaluate the Listeria abundance (as free-living and plankton associated species) and physicochemical qualities of the final effluents of three wastewater treatment facilities in the Eastern Cape Province of South Africa selected to represent typical urban, peri-urban and rural communities and the impact of the discharged final effluents on their respective receiving watershed, as well as to elucidated the in vitro antibiotic susceptibilities and resistance genes profile of Listeria species isolated from the final effluents. The suitability of the secondary effluent of the urban treatment facility (as a case study) for use in agriculture and aquaculture with reference to recommended standards was also determined. Wastewater samples were collected from the raw sewage, secondary effluent, final treated effluent, discharge point, 500 m upstream discharge point, and 500 m downstream discharge point from all three locations on a monthly basis throughout the study period. Listeria abundance in the final effluents and the receiving watersheds varied between 2.9× 100 and 3.52 × 105cfu/ml across the sampled locations. Free-living listerial density across the sampled locations ranged between 0 and 3.2 × 103cfu/ml while counts of Listeria species attached to large (180 μm) planktons varied from 0 to 1.58 × 105 cfu/ml and those of the 60 and 20 μm categories were in the range of 0 to 1.32 × 103 cfu/ml and 0 to 2.82 × 105 cfu/ml respectively. Listeria abundance did not vary significantly with location and season; there was however, significant (P < 0.05; P < 0.01) variance in Listeria abundance with plankton sizes across the locations. Free-living Listeria species were more abundant in the rural and urban xii communities than plankton attached Listeria species; whereas the reverse was the case in the peri-urban community.
- Full Text:
- Date Issued: 2010
- Authors: Odjadjare, Emmanuel Erufuare Onogwuwhenya
- Date: 2010
- Subjects: Listeria -- South Africa -- Eastern Cape Sewage -- Purification -- South Africa -- Eastern Cape Water -- Pollution -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/7826 , vital:30747
- Description: astewater discharges may contain health compromising pathogens and carcinogenic and/or chemical substances that could compromise the public health and impact negatively on the environment. The present study was conducted between August 2007 and July 2008 to evaluate the Listeria abundance (as free-living and plankton associated species) and physicochemical qualities of the final effluents of three wastewater treatment facilities in the Eastern Cape Province of South Africa selected to represent typical urban, peri-urban and rural communities and the impact of the discharged final effluents on their respective receiving watershed, as well as to elucidated the in vitro antibiotic susceptibilities and resistance genes profile of Listeria species isolated from the final effluents. The suitability of the secondary effluent of the urban treatment facility (as a case study) for use in agriculture and aquaculture with reference to recommended standards was also determined. Wastewater samples were collected from the raw sewage, secondary effluent, final treated effluent, discharge point, 500 m upstream discharge point, and 500 m downstream discharge point from all three locations on a monthly basis throughout the study period. Listeria abundance in the final effluents and the receiving watersheds varied between 2.9× 100 and 3.52 × 105cfu/ml across the sampled locations. Free-living listerial density across the sampled locations ranged between 0 and 3.2 × 103cfu/ml while counts of Listeria species attached to large (180 μm) planktons varied from 0 to 1.58 × 105 cfu/ml and those of the 60 and 20 μm categories were in the range of 0 to 1.32 × 103 cfu/ml and 0 to 2.82 × 105 cfu/ml respectively. Listeria abundance did not vary significantly with location and season; there was however, significant (P < 0.05; P < 0.01) variance in Listeria abundance with plankton sizes across the locations. Free-living Listeria species were more abundant in the rural and urban xii communities than plankton attached Listeria species; whereas the reverse was the case in the peri-urban community.
- Full Text:
- Date Issued: 2010
Synthesis, characterization and reactions of novel ferrocenylimidazoles as donor ligands
- Authors: Onyancha, Douglas Okerio
- Date: 2010
- Subjects: Ferrocene
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10390 , http://hdl.handle.net/10948/1150 , Ferrocene
- Description: In this project a series of ferrocenylimidazole derivatives were successfully prepared and characterized using an array of analytical techniques. Reactions of ferrocenylcarbinols with N,N′-thiocarbonyldiimidazole under both solvent-free conditions and in dichloromethane are described. The reaction of ferrocenylmethanol afforded S,S-bis(ferrocenylmethyl)dithiocarbonate, the reaction of α-substituted ferrocenylcarbinols provided ferrocenylalkylimidazolides, while ω-ferrocenylcarbinols yielded ferrocenylimidazolecarbothioates. The reactions were carried out under solvent-free conditions, consistent with the principles of Green Chemistry. Ferrocenyl benzyl ethers were successfully prepared by reacting 4-ferrocenylbenzyl-1Hcarboxylate with a series of primary alcohols under catalytic condition and under a catalyst– free environment. Refluxing a mixture of alcohol-water and 4-ferrocenylbenzyl-1Hcarboxylate provided the corresponding ethers in modest yields. The same ethers were obtained at room temperature by employing potassium tetrachloroplatinate or hydrochloric acid as catalyst. Ferrocenyl-1H-imidazole, 4-ferrocenylphenyl-1H-imidazole and their corresponding ferrocenyl-3-subsitituted imidazolium salts have been successfully synthesized. The compounds were characterized and the electrochemical properties of selected imidazolium salts were examined by cyclic voltammetry. Additionally, X-ray structures of two of the imidazolium salts were determined. The imidazolium salts were found to be good catalysts for the Heck and Suzuki cross-coupling reactions.
- Full Text:
- Date Issued: 2010
- Authors: Onyancha, Douglas Okerio
- Date: 2010
- Subjects: Ferrocene
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10390 , http://hdl.handle.net/10948/1150 , Ferrocene
- Description: In this project a series of ferrocenylimidazole derivatives were successfully prepared and characterized using an array of analytical techniques. Reactions of ferrocenylcarbinols with N,N′-thiocarbonyldiimidazole under both solvent-free conditions and in dichloromethane are described. The reaction of ferrocenylmethanol afforded S,S-bis(ferrocenylmethyl)dithiocarbonate, the reaction of α-substituted ferrocenylcarbinols provided ferrocenylalkylimidazolides, while ω-ferrocenylcarbinols yielded ferrocenylimidazolecarbothioates. The reactions were carried out under solvent-free conditions, consistent with the principles of Green Chemistry. Ferrocenyl benzyl ethers were successfully prepared by reacting 4-ferrocenylbenzyl-1Hcarboxylate with a series of primary alcohols under catalytic condition and under a catalyst– free environment. Refluxing a mixture of alcohol-water and 4-ferrocenylbenzyl-1Hcarboxylate provided the corresponding ethers in modest yields. The same ethers were obtained at room temperature by employing potassium tetrachloroplatinate or hydrochloric acid as catalyst. Ferrocenyl-1H-imidazole, 4-ferrocenylphenyl-1H-imidazole and their corresponding ferrocenyl-3-subsitituted imidazolium salts have been successfully synthesized. The compounds were characterized and the electrochemical properties of selected imidazolium salts were examined by cyclic voltammetry. Additionally, X-ray structures of two of the imidazolium salts were determined. The imidazolium salts were found to be good catalysts for the Heck and Suzuki cross-coupling reactions.
- Full Text:
- Date Issued: 2010