Electrochemistry and photophysicochemical studies of titanium, tantalum and vanadium phthalocyanines in the presence of nanomaterials
- Authors: Chauke, Vongani Portia
- Date: 2012
- Subjects: Phthalocyanines -- Synthesis Electrochemistry Titanium Tantalum Vanadium
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4313 , http://hdl.handle.net/10962/d1004971
- Description: The syntheses of tetra- and octa-substituted phthalocyanine complexes of titanium (IV) oxide vanadium (IV) oxide and tantalum (V) hydroxide and their electrochemical characterisation are presented in this work. The structures and purity of these complexes were confirmed by NMR, infrared and mass spectroscopies and elemental analysis. They show good solubility in most common solvents especially non-viscous solvents such as dichloromethane and chloroform. The cyclic voltammograms (CV) showed reversible to quasi reversible behavior for all the reduction couples and the oxidation peaks were irreversible. Spectroelectrochemistry of the complexes confirmed metal and ring redox processes for TaPc and TiPc derivatives and ring based processes only for VPc complexes. The synthesis of gold nanoparticles and their conjugation with the new phthalocyanines was carried out. Similarly, single walled carbon nanotubes were conjugated to selected tantalum complexes and the characterization of all the nanomaterials and their conjugates using different techniques that include TEM, XRD and AFM is also presented in this work. The photophysical and photochemical properties and photocatalytic oxidation of cyclohexene properties of the newly synthesised in the presence of gold nanoparticles were investigated. The compounds were stable, well within the stability range for phthalocyanines. The singlet oxygen quantum yield values increased drastically in the presence of gold nanoparticles. The photocatalytic products obtained from the reaction were cyclohexene oxide, 2-cyclohexen-1-ol, 2-cyclohexene-1-one and 1,4-cyclohexanediol. The percentage conversion values, yields and selectivity values improved significantly in the presence of AuNPs. Singlet oxygen was determined to be the main agent involved in the photocatalytic oxidation of cyclohexene. The electrocatalytic oxidation of bisphenol A and p-nitrophenol was carried out using nickel tetraamino phthalocyanine and all the newly synthesised metallophthalocyanine in the presence of gold nanoparticles and single walled carbon nanotubes. The charge transfer behaviour of AuNPs was enhanced in the presence of TaPc, TiPc and VPc complexes. The presence of single walled carbon nanotubes further improved electron transfer and minimised electrode passivation.
- Full Text:
- Date Issued: 2012
- Authors: Chauke, Vongani Portia
- Date: 2012
- Subjects: Phthalocyanines -- Synthesis Electrochemistry Titanium Tantalum Vanadium
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4313 , http://hdl.handle.net/10962/d1004971
- Description: The syntheses of tetra- and octa-substituted phthalocyanine complexes of titanium (IV) oxide vanadium (IV) oxide and tantalum (V) hydroxide and their electrochemical characterisation are presented in this work. The structures and purity of these complexes were confirmed by NMR, infrared and mass spectroscopies and elemental analysis. They show good solubility in most common solvents especially non-viscous solvents such as dichloromethane and chloroform. The cyclic voltammograms (CV) showed reversible to quasi reversible behavior for all the reduction couples and the oxidation peaks were irreversible. Spectroelectrochemistry of the complexes confirmed metal and ring redox processes for TaPc and TiPc derivatives and ring based processes only for VPc complexes. The synthesis of gold nanoparticles and their conjugation with the new phthalocyanines was carried out. Similarly, single walled carbon nanotubes were conjugated to selected tantalum complexes and the characterization of all the nanomaterials and their conjugates using different techniques that include TEM, XRD and AFM is also presented in this work. The photophysical and photochemical properties and photocatalytic oxidation of cyclohexene properties of the newly synthesised in the presence of gold nanoparticles were investigated. The compounds were stable, well within the stability range for phthalocyanines. The singlet oxygen quantum yield values increased drastically in the presence of gold nanoparticles. The photocatalytic products obtained from the reaction were cyclohexene oxide, 2-cyclohexen-1-ol, 2-cyclohexene-1-one and 1,4-cyclohexanediol. The percentage conversion values, yields and selectivity values improved significantly in the presence of AuNPs. Singlet oxygen was determined to be the main agent involved in the photocatalytic oxidation of cyclohexene. The electrocatalytic oxidation of bisphenol A and p-nitrophenol was carried out using nickel tetraamino phthalocyanine and all the newly synthesised metallophthalocyanine in the presence of gold nanoparticles and single walled carbon nanotubes. The charge transfer behaviour of AuNPs was enhanced in the presence of TaPc, TiPc and VPc complexes. The presence of single walled carbon nanotubes further improved electron transfer and minimised electrode passivation.
- Full Text:
- Date Issued: 2012
Spermiogenesis, sperm ultrastructure and reproductive tract morphology in cicadas implications for systematic relationships
- Chawanji, Abraham Simbarashe
- Authors: Chawanji, Abraham Simbarashe
- Date: 2007
- Subjects: Cicadas Cicadas -- Reproduction Spermiogenesis in animals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5770 , http://hdl.handle.net/10962/d1005458
- Description: Sperm structure in five species of cicadine cicadas (Albanycada albigera, Azanicada zuluensis, Platypleura capensis, P. hirtipennis and Pycna semiclara) and five species of cicadettine cicadas (Melampsalta leucoptera, Quintilia walkeri, Stagira simplex, Xosopsaltria thunbergi and Monomatapa matoposa) was investigated by light and electron microscopy. In addition, spermiogenesis in cicadas was described; the information was derived from two cicadettines (Diceroprocta biconica and M. matoposa) and three cicadines (Kongota punctigera, P. capensis and P. semiclara). Mature spermatozoa of all species investigated are elongate and filiform, consisting of three distinct regions: the head (acrosome and nucleus), mid-piece and tail. All species produce more than one discrete length of nucleated, motile sperm, a form of sperm polymorphism termed polymegaly. Polymegaly is expressed in three ways; sperm have uni-, bi- or trimodal nucleus and tail lengths. Besides the differences in length, there are also notable differences in the size of nuclei. The anterior parts of sperm heads are embedded in an elongate homogenous matrix forming spermatodesmata. The conical acrosome is deeply invaginated posteriorly, and sits on top of the nucleus. The acrosomal contents are differentiated internally with a tubular substructure and a subacrosomal space. The anterior of the nucleus intrudes into the posterior section of the subacrosomal space. Anteriorly the acrosome is laterally flattened; posteriorly it extends as two tubular processes on either side of the nucleus that gradually decrease in diameter. The homogenously electron-dense nucleus is pointed anteriorly and is generally cylindrical, although posteriorly there is a lateral invagination that extends part-way along the nucleus. This invagination houses fine granular material of the putative centriolar adjunct which does not form in close proximity to the centriole and hence may not be a true centriolar adjunct. The lamellate disposition of the centriolar adjunct material within the sperm-midpiece of cicadettine cicadas is distinct, and separates these cicadas from their cicadine counterparts in which the centriolar adjunct material is non-lamellate. Vesicle-like elements that are associated with both the posterior nucleus and the centriolar adjunct are also found within the invagination. Immediately posterior of and adjoining the centriolar adjunct is a pair of mitochondrial derivatives that are elongated and extend for almost the entire length of the tail. Except for size the architecture of short and long spermatozoa is generally similar in all species. The absence of accessory bodies in cicada sperm suggests that within the Cicadomorpha, the families Cicadidae and Cercopidae are closely related. Only long nuclei were observed in the fertilized eggs of A. zuluensis indicating that sperm with long nuclei might be favoured for fertilization. Spermiogenesis involves: (a) development of the acrosome from a proacrosomal granule; (b) development of the nucleus, characterized by elongation and streamlining with a simultaneous condensation of chromatin; (c) development of the axoneme from the centriole; (d) amalgamation of individual small mitochondria to form elongated mitochondrial derivatives in which cristae are arranged into regularly spaced lamellae; and (f) elimination of cytoplasm. The presence of a manchette, a transient microtubular organelle, which surrounds the acrosome, nucleus and mitochondrial derivatives, is a characteristic feature of spermiogenesis. The gross morphology of the reproductive tract in both male and female cicadas exhibits an organization similar to that in most oviparous insects. The non-functional spermatheca is the only exceptional feature in the female reproductive tract. Its role has been taken over by the common oviduct which, subsequently, has become modified into a swollen, differentiated structure with a dual role of receiving oocytes from the paired ovaries and storage of spermatozoa. Testis mass varies between cicada species; this variation might be linked to the intensity of sperm competition which has been found to be positively correlated with relative investment in spermatogenesis. Based on the preliminary findings of this study, K. punctigera, with its larger testis relative to body size, would be the ideal candidate to show the greatest levels of sperm competition. Accessory glands in both male and female A. zuluensis, D. biconica, P. hirtipennis and O. quadraticollis are very long; this character might be of phylogenetic significance. Despite being notoriously refractory spermiocladistics is potentially valuable in systematic and phylogenic studies of cicadas, especially at the subfamily level.
- Full Text:
- Date Issued: 2007
- Authors: Chawanji, Abraham Simbarashe
- Date: 2007
- Subjects: Cicadas Cicadas -- Reproduction Spermiogenesis in animals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5770 , http://hdl.handle.net/10962/d1005458
- Description: Sperm structure in five species of cicadine cicadas (Albanycada albigera, Azanicada zuluensis, Platypleura capensis, P. hirtipennis and Pycna semiclara) and five species of cicadettine cicadas (Melampsalta leucoptera, Quintilia walkeri, Stagira simplex, Xosopsaltria thunbergi and Monomatapa matoposa) was investigated by light and electron microscopy. In addition, spermiogenesis in cicadas was described; the information was derived from two cicadettines (Diceroprocta biconica and M. matoposa) and three cicadines (Kongota punctigera, P. capensis and P. semiclara). Mature spermatozoa of all species investigated are elongate and filiform, consisting of three distinct regions: the head (acrosome and nucleus), mid-piece and tail. All species produce more than one discrete length of nucleated, motile sperm, a form of sperm polymorphism termed polymegaly. Polymegaly is expressed in three ways; sperm have uni-, bi- or trimodal nucleus and tail lengths. Besides the differences in length, there are also notable differences in the size of nuclei. The anterior parts of sperm heads are embedded in an elongate homogenous matrix forming spermatodesmata. The conical acrosome is deeply invaginated posteriorly, and sits on top of the nucleus. The acrosomal contents are differentiated internally with a tubular substructure and a subacrosomal space. The anterior of the nucleus intrudes into the posterior section of the subacrosomal space. Anteriorly the acrosome is laterally flattened; posteriorly it extends as two tubular processes on either side of the nucleus that gradually decrease in diameter. The homogenously electron-dense nucleus is pointed anteriorly and is generally cylindrical, although posteriorly there is a lateral invagination that extends part-way along the nucleus. This invagination houses fine granular material of the putative centriolar adjunct which does not form in close proximity to the centriole and hence may not be a true centriolar adjunct. The lamellate disposition of the centriolar adjunct material within the sperm-midpiece of cicadettine cicadas is distinct, and separates these cicadas from their cicadine counterparts in which the centriolar adjunct material is non-lamellate. Vesicle-like elements that are associated with both the posterior nucleus and the centriolar adjunct are also found within the invagination. Immediately posterior of and adjoining the centriolar adjunct is a pair of mitochondrial derivatives that are elongated and extend for almost the entire length of the tail. Except for size the architecture of short and long spermatozoa is generally similar in all species. The absence of accessory bodies in cicada sperm suggests that within the Cicadomorpha, the families Cicadidae and Cercopidae are closely related. Only long nuclei were observed in the fertilized eggs of A. zuluensis indicating that sperm with long nuclei might be favoured for fertilization. Spermiogenesis involves: (a) development of the acrosome from a proacrosomal granule; (b) development of the nucleus, characterized by elongation and streamlining with a simultaneous condensation of chromatin; (c) development of the axoneme from the centriole; (d) amalgamation of individual small mitochondria to form elongated mitochondrial derivatives in which cristae are arranged into regularly spaced lamellae; and (f) elimination of cytoplasm. The presence of a manchette, a transient microtubular organelle, which surrounds the acrosome, nucleus and mitochondrial derivatives, is a characteristic feature of spermiogenesis. The gross morphology of the reproductive tract in both male and female cicadas exhibits an organization similar to that in most oviparous insects. The non-functional spermatheca is the only exceptional feature in the female reproductive tract. Its role has been taken over by the common oviduct which, subsequently, has become modified into a swollen, differentiated structure with a dual role of receiving oocytes from the paired ovaries and storage of spermatozoa. Testis mass varies between cicada species; this variation might be linked to the intensity of sperm competition which has been found to be positively correlated with relative investment in spermatogenesis. Based on the preliminary findings of this study, K. punctigera, with its larger testis relative to body size, would be the ideal candidate to show the greatest levels of sperm competition. Accessory glands in both male and female A. zuluensis, D. biconica, P. hirtipennis and O. quadraticollis are very long; this character might be of phylogenetic significance. Despite being notoriously refractory spermiocladistics is potentially valuable in systematic and phylogenic studies of cicadas, especially at the subfamily level.
- Full Text:
- Date Issued: 2007
KwaZakele: the politics of transition in South Africa: an Eastern Cape case study
- Authors: Cherry, Janet Mary
- Date: 2001
- Subjects: South Africa -- Transition to democracy Democracy -- South Africa -- Eastern Cape Eastern Cape (South Africa) -- Politics and government Port Elizabeth region (South Africa) -- Political aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2766 , http://hdl.handle.net/10962/d1002976
- Description: This thesis examines the transition to democracy in South Africa through the use of case study methodology. The nature of political participation and the form of democracy to emerge at the end of the transition process are the central subjects of inquiry. They are examined through an in-depth study of the African community of Kwazakele, a township in the Nelson Mandela metropolitan area in the Eastern Cape province of South Africa. The study covers the period from 1993 to 2000, and uses as a primary data source five surveys conducted among residents of Kwazakele during that period. The emphasis of the study lies on the experience of political participation of ‘ordinary people’ – in particular, the African urban working-class in South Africa who make up the core support base for the governing African National Congress. The primary findings of the thesis are as follows: * Representative democracy has been successfully consolidated in the community under study. * Levels of political participation by urban Africans in the Eastern Cape are consistently high, both in formal political institutions (primarily elections) and in institutions of civil society. * As politics has normalised at the end of the transition period, forms of direct democratic participation have declined. * Despite the structural constraints on development, there is still potential for a high level of participation by citizens in effecting change at local level. * Drawing on the experience of ordinary people in structures of direct democracy, this level of participation can result in a deeper and stronger form of democracy than exists in many established representative democracies.
- Full Text:
- Date Issued: 2001
- Authors: Cherry, Janet Mary
- Date: 2001
- Subjects: South Africa -- Transition to democracy Democracy -- South Africa -- Eastern Cape Eastern Cape (South Africa) -- Politics and government Port Elizabeth region (South Africa) -- Political aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2766 , http://hdl.handle.net/10962/d1002976
- Description: This thesis examines the transition to democracy in South Africa through the use of case study methodology. The nature of political participation and the form of democracy to emerge at the end of the transition process are the central subjects of inquiry. They are examined through an in-depth study of the African community of Kwazakele, a township in the Nelson Mandela metropolitan area in the Eastern Cape province of South Africa. The study covers the period from 1993 to 2000, and uses as a primary data source five surveys conducted among residents of Kwazakele during that period. The emphasis of the study lies on the experience of political participation of ‘ordinary people’ – in particular, the African urban working-class in South Africa who make up the core support base for the governing African National Congress. The primary findings of the thesis are as follows: * Representative democracy has been successfully consolidated in the community under study. * Levels of political participation by urban Africans in the Eastern Cape are consistently high, both in formal political institutions (primarily elections) and in institutions of civil society. * As politics has normalised at the end of the transition period, forms of direct democratic participation have declined. * Despite the structural constraints on development, there is still potential for a high level of participation by citizens in effecting change at local level. * Drawing on the experience of ordinary people in structures of direct democracy, this level of participation can result in a deeper and stronger form of democracy than exists in many established representative democracies.
- Full Text:
- Date Issued: 2001
The construction of household livelihood strategies in urban areas: the case of Budiriro, Harare, Zimbabwe
- Authors: Chevo, Tafadzwa
- Date: 2018
- Subjects: Income -- Zimbabwe -- Harare , Cost and standard of living -- Zimbabwe -- Harare , Quality of life -- Zimbabwe -- Harare , Informal sector (Economics) -- Zimbabwe -- Harare , Agricultural wages -- Zimbabwe -- Harare , Households -- Economic aspects -- Zimbabwe -- Harare , Macrosociology , Zimbabwe -- Social conditions -- 1980- , Zimbabwe -- Economic conditions -- 1980- , Livelihoods Framework
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63043 , vital:28357
- Description: The main objective of this thesis is to understand and explain the ongoing construction of livelihood activities by urban households in the low-income high-density area of Budiriro, Harare, Zimbabwe in a context characterised by systemic crisis and a general decline of the national economy. The study utilised a mixed methods research approach, which combined both qualitative and quantitative research, including a survey, life histories and focus group discussions. The thesis discusses a diverse range of livelihood activities of Budiriro households, such as formal employment, informal trading and agricultural activities, and the ways in which households seeks to diversify their livelihood portfolio. It does this by way of also examining the contemporary and historical factors influencing the livelihood activities pursued by these households, along with the shocks and disturbances encountered and experienced by households in trying to construct viable livelihoods. The thesis makes useful contributions to the existing literature on livelihoods studies. Firstly, the thesis disaggregates the households by showing the existence of three wealth categories in Budiriro and the varying livelihood strategies of households in different wealth categories. Secondly, the study highlights the significance of intra-household dynamics in Budiriro for livelihoods as well as of inter-household kinship networks, which transcend the urban space and entail multi-spatial livelihoods. Thirdly, the thesis examines livelihoods over time, such that it goes beyond a strictly synchronic examination, therefore providing a diachronic analysis of diverse and complicated livelihood pathways. Finally, the Livelihoods Framework is located within broader macro-sociological theorising including the work of Pierre Bourdieu. In this respect, important insights arise about livelihood choices and practices in the light of ongoing debates within sociology about human agency.
- Full Text:
- Date Issued: 2018
- Authors: Chevo, Tafadzwa
- Date: 2018
- Subjects: Income -- Zimbabwe -- Harare , Cost and standard of living -- Zimbabwe -- Harare , Quality of life -- Zimbabwe -- Harare , Informal sector (Economics) -- Zimbabwe -- Harare , Agricultural wages -- Zimbabwe -- Harare , Households -- Economic aspects -- Zimbabwe -- Harare , Macrosociology , Zimbabwe -- Social conditions -- 1980- , Zimbabwe -- Economic conditions -- 1980- , Livelihoods Framework
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63043 , vital:28357
- Description: The main objective of this thesis is to understand and explain the ongoing construction of livelihood activities by urban households in the low-income high-density area of Budiriro, Harare, Zimbabwe in a context characterised by systemic crisis and a general decline of the national economy. The study utilised a mixed methods research approach, which combined both qualitative and quantitative research, including a survey, life histories and focus group discussions. The thesis discusses a diverse range of livelihood activities of Budiriro households, such as formal employment, informal trading and agricultural activities, and the ways in which households seeks to diversify their livelihood portfolio. It does this by way of also examining the contemporary and historical factors influencing the livelihood activities pursued by these households, along with the shocks and disturbances encountered and experienced by households in trying to construct viable livelihoods. The thesis makes useful contributions to the existing literature on livelihoods studies. Firstly, the thesis disaggregates the households by showing the existence of three wealth categories in Budiriro and the varying livelihood strategies of households in different wealth categories. Secondly, the study highlights the significance of intra-household dynamics in Budiriro for livelihoods as well as of inter-household kinship networks, which transcend the urban space and entail multi-spatial livelihoods. Thirdly, the thesis examines livelihoods over time, such that it goes beyond a strictly synchronic examination, therefore providing a diachronic analysis of diverse and complicated livelihood pathways. Finally, the Livelihoods Framework is located within broader macro-sociological theorising including the work of Pierre Bourdieu. In this respect, important insights arise about livelihood choices and practices in the light of ongoing debates within sociology about human agency.
- Full Text:
- Date Issued: 2018
The effects of land use on the avifauna and its conservation in a Kenyan coastal forest ecosystem, and the significance of the Arabuko Sokoke Forest to the local community
- Authors: Chiawo, David O
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5950 , http://hdl.handle.net/10962/d1020946
- Description: This study examines the effects of land use on the bird community of Arabuko Sokoke Forest, the largest area of coastal forest remaining in East Africa and a major Important Bird Area in mainland Kenya. Bird species diversity in three land use types (primary forest, plantation and farm lands) was compared using multivariate analysis to determine the response of different feeding guilds to habitat characteristics. The effect of habitat characteristics on overall bird diversity and specific feeding guilds was tested using linear mixed models. A total of 2600 bird observations were recorded during point counts, representing 97 bird species including 25 fruit-eating birds, 17 nectar feeders; and 60 species belonging exclusively to other feeding guilds. Land use had a significant effect on overall bird diversity and abundance. The distribution of frugivorous birds was primarily influenced by the presence of fruiting trees rather than land use type, while nectarivores were significantly affected by vertical habitat heterogeneity and vegetation type. Although the distribution of insectivorous birds is influenced by many habitat factors, proximity to natural forest, habitat heterogeneity, and the presence of large trees and fruiting trees appear to be most important to this guild. The natural forest has the greatest avian diversity and a distinctive community compared to plantation and farmlands. Patterns of habitat use by birds in the area suggest that vertical vegetation heterogeneity and complexity is especially significant in sustaining diverse and abundant bird populations, if they are in close proximity to native forests. Improvement of conservation management for the plantation and farmlands is thus critical for connectivity with other remnant primary forest patches in the area. Socio-economic data was collected from 109 forest adjacent households to determine the value of the forest to the local community and their perception of conservation issues. Arabuko Sokoke Forest is important in supplementing the livelihood needs of the local community. However, the community lacks information on the forest management plan and many people have little knowledge of local birds, which could limit their capacity to participate in conservation projects. Drivers for local community participation in conservation projects are primarily a sustainable income and the fulfillment of basic household needs. Community conservation education is needed to promote local knowledge of forest biodiversity, as well as clear frameworks for the active involvement of the local community in forest management. Support of community based projects is vital to achieve both the conservation and livelihood objectives of the Arabuko Sokoke Forest management plan.
- Full Text:
- Date Issued: 2016
- Authors: Chiawo, David O
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5950 , http://hdl.handle.net/10962/d1020946
- Description: This study examines the effects of land use on the bird community of Arabuko Sokoke Forest, the largest area of coastal forest remaining in East Africa and a major Important Bird Area in mainland Kenya. Bird species diversity in three land use types (primary forest, plantation and farm lands) was compared using multivariate analysis to determine the response of different feeding guilds to habitat characteristics. The effect of habitat characteristics on overall bird diversity and specific feeding guilds was tested using linear mixed models. A total of 2600 bird observations were recorded during point counts, representing 97 bird species including 25 fruit-eating birds, 17 nectar feeders; and 60 species belonging exclusively to other feeding guilds. Land use had a significant effect on overall bird diversity and abundance. The distribution of frugivorous birds was primarily influenced by the presence of fruiting trees rather than land use type, while nectarivores were significantly affected by vertical habitat heterogeneity and vegetation type. Although the distribution of insectivorous birds is influenced by many habitat factors, proximity to natural forest, habitat heterogeneity, and the presence of large trees and fruiting trees appear to be most important to this guild. The natural forest has the greatest avian diversity and a distinctive community compared to plantation and farmlands. Patterns of habitat use by birds in the area suggest that vertical vegetation heterogeneity and complexity is especially significant in sustaining diverse and abundant bird populations, if they are in close proximity to native forests. Improvement of conservation management for the plantation and farmlands is thus critical for connectivity with other remnant primary forest patches in the area. Socio-economic data was collected from 109 forest adjacent households to determine the value of the forest to the local community and their perception of conservation issues. Arabuko Sokoke Forest is important in supplementing the livelihood needs of the local community. However, the community lacks information on the forest management plan and many people have little knowledge of local birds, which could limit their capacity to participate in conservation projects. Drivers for local community participation in conservation projects are primarily a sustainable income and the fulfillment of basic household needs. Community conservation education is needed to promote local knowledge of forest biodiversity, as well as clear frameworks for the active involvement of the local community in forest management. Support of community based projects is vital to achieve both the conservation and livelihood objectives of the Arabuko Sokoke Forest management plan.
- Full Text:
- Date Issued: 2016
An investigation into XSets of primitive behaviours for emergent behaviour in stigmergic and message passing antlike agents
- Authors: Chibaya, Colin
- Date: 2014
- Subjects: Ants -- Behavior -- Computer programs , Insects -- Behavior -- Computer programs , Ant communities -- Behavior , Insect societies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4698 , http://hdl.handle.net/10962/d1012965
- Description: Ants are fascinating creatures - not so much because they are intelligent on their own, but because as a group they display compelling emergent behaviour (the extent to which one observes features in a swarm which cannot be traced back to the actions of swarm members). What does each swarm member do which allows deliberate engineering of emergent behaviour? We investigate the development of a language for programming swarms of ant agents towards desired emergent behaviour. Five aspects of stigmergic (pheromone sensitive computational devices in which a non-symbolic form of communication that is indirectly mediated via the environment arises) and message passing ant agents (computational devices which rely on implicit communication spaces in which direction vectors are shared one-on-one) are studied. First, we investigate the primitive behaviours which characterize ant agents' discrete actions at individual levels. Ten such primitive behaviours are identified as candidate building blocks of the ant agent language sought. We then study mechanisms in which primitive behaviours are put together into XSets (collection of primitive behaviours, parameter values, and meta information which spells out how and when primitive behaviours are used). Various permutations of XSets are possible which define the search space for best performer XSets for particular tasks. Genetic programming principles are proposed as a search strategy for best performer XSets that would allow particular emergent behaviour to occur. XSets in the search space are evolved over various genetic generations and tested for abilities to allow path finding (as proof of concept). XSets are ranked according to the indices of merit (fitness measures which indicate how well XSets allow particular emergent behaviour to occur) they achieve. Best performer XSets for the path finding task are identifed and reported. We validate the results yield when best performer XSets are used with regard to normality, correlation, similarities in variation, and similarities between mean performances over time. Commonly, the simulation results yield pass most statistical tests. The last aspect we study is the application of best performer XSets to different problem tasks. Five experiments are administered in this regard. The first experiment assesses XSets' abilities to allow multiple targets location (ant agents' abilities to locate continuous regions of targets), and found out that best performer XSets are problem independent. However both categories of XSets are sensitive to changes in agent density. We test the influences of individual primitive behaviours and the effects of the sequences of primitive behaviours to the indices of merit of XSets and found out that most primitive behaviours are indispensable, especially when specific sequences are prescribed. The effects of pheromone dissipation to the indices of merit of stigmergic XSets are also scrutinized. Precisely, dissipation is not causal. Rather, it enhances convergence. Overall, this work successfully identify the discrete primitive behaviours of stigmergic and message passing ant-like devices. It successfully put these primitive behaviours together into XSets which characterize a language for programming ant-like devices towards desired emergent behaviour. This XSets approach is a new ant language representation with which a wider domain of emergent tasks can be resolved.
- Full Text:
- Date Issued: 2014
- Authors: Chibaya, Colin
- Date: 2014
- Subjects: Ants -- Behavior -- Computer programs , Insects -- Behavior -- Computer programs , Ant communities -- Behavior , Insect societies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4698 , http://hdl.handle.net/10962/d1012965
- Description: Ants are fascinating creatures - not so much because they are intelligent on their own, but because as a group they display compelling emergent behaviour (the extent to which one observes features in a swarm which cannot be traced back to the actions of swarm members). What does each swarm member do which allows deliberate engineering of emergent behaviour? We investigate the development of a language for programming swarms of ant agents towards desired emergent behaviour. Five aspects of stigmergic (pheromone sensitive computational devices in which a non-symbolic form of communication that is indirectly mediated via the environment arises) and message passing ant agents (computational devices which rely on implicit communication spaces in which direction vectors are shared one-on-one) are studied. First, we investigate the primitive behaviours which characterize ant agents' discrete actions at individual levels. Ten such primitive behaviours are identified as candidate building blocks of the ant agent language sought. We then study mechanisms in which primitive behaviours are put together into XSets (collection of primitive behaviours, parameter values, and meta information which spells out how and when primitive behaviours are used). Various permutations of XSets are possible which define the search space for best performer XSets for particular tasks. Genetic programming principles are proposed as a search strategy for best performer XSets that would allow particular emergent behaviour to occur. XSets in the search space are evolved over various genetic generations and tested for abilities to allow path finding (as proof of concept). XSets are ranked according to the indices of merit (fitness measures which indicate how well XSets allow particular emergent behaviour to occur) they achieve. Best performer XSets for the path finding task are identifed and reported. We validate the results yield when best performer XSets are used with regard to normality, correlation, similarities in variation, and similarities between mean performances over time. Commonly, the simulation results yield pass most statistical tests. The last aspect we study is the application of best performer XSets to different problem tasks. Five experiments are administered in this regard. The first experiment assesses XSets' abilities to allow multiple targets location (ant agents' abilities to locate continuous regions of targets), and found out that best performer XSets are problem independent. However both categories of XSets are sensitive to changes in agent density. We test the influences of individual primitive behaviours and the effects of the sequences of primitive behaviours to the indices of merit of XSets and found out that most primitive behaviours are indispensable, especially when specific sequences are prescribed. The effects of pheromone dissipation to the indices of merit of stigmergic XSets are also scrutinized. Precisely, dissipation is not causal. Rather, it enhances convergence. Overall, this work successfully identify the discrete primitive behaviours of stigmergic and message passing ant-like devices. It successfully put these primitive behaviours together into XSets which characterize a language for programming ant-like devices towards desired emergent behaviour. This XSets approach is a new ant language representation with which a wider domain of emergent tasks can be resolved.
- Full Text:
- Date Issued: 2014
Photophysiochemical studies of d¹⁰ metallophthalocyanines and their interaction with nanoparticles
- Chidawanyika, Wadzanai Janet Upenyu
- Authors: Chidawanyika, Wadzanai Janet Upenyu
- Date: 2010
- Subjects: Nanoparticles Phthalocyanines Photochemistry Electrochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4335 , http://hdl.handle.net/10962/d1004996
- Description: The syntheses, extensive spectroscopic characterization, photophysical and photochemical studies have been conducted for a variation of d10 metallophthaloycanines (MPcs). Comparisons have been made taking into consideration the nfluence of the central metal ion, solvent properties, substituent type and position. Coordination to heavy central metals i.e. Hg gives enhanced triplet state properties. Low symmetry metallophthalocyanine complexes were similarly haracterized and the influence of nteractions with nanoparticles on their photophysical and photochemical properties determined. The MPcs have been linked and adsorbed or mixed with nanoparticles i.e. hemically functionalized single-walled carbon nanotubes SWCNT) and mercaptocarboxylic acid capped CdTe quantum dots (QDs) and changes in the spectra accounted for with respect to the proposed conjugate structures. Distinct differences ccur for linked and adsorbed or mixed conjugates in the bsorption, infrared (IR) and Raman spectra and for thermal ravimetric decay profiles, suggesting successful formation f covalent bonds (linked) and point to structurally ifferent materials. SWCNT quench MPc fluorescence by a photoinduced electron transfer mediated process to give low fluorescence quantum yields. The QDs were used as energy transfer donors and facilitate energy transfer, through Förster resonance energy transfer (FRET) from the QDs to the MPcs. Improved FRET efficiencies were found for linked MPc-QD conjugates relative to the mixed species. Photophysicochemical properties of MPcs were, in general, improved as a result of interactions with nanoparticles.
- Full Text:
- Date Issued: 2010
- Authors: Chidawanyika, Wadzanai Janet Upenyu
- Date: 2010
- Subjects: Nanoparticles Phthalocyanines Photochemistry Electrochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4335 , http://hdl.handle.net/10962/d1004996
- Description: The syntheses, extensive spectroscopic characterization, photophysical and photochemical studies have been conducted for a variation of d10 metallophthaloycanines (MPcs). Comparisons have been made taking into consideration the nfluence of the central metal ion, solvent properties, substituent type and position. Coordination to heavy central metals i.e. Hg gives enhanced triplet state properties. Low symmetry metallophthalocyanine complexes were similarly haracterized and the influence of nteractions with nanoparticles on their photophysical and photochemical properties determined. The MPcs have been linked and adsorbed or mixed with nanoparticles i.e. hemically functionalized single-walled carbon nanotubes SWCNT) and mercaptocarboxylic acid capped CdTe quantum dots (QDs) and changes in the spectra accounted for with respect to the proposed conjugate structures. Distinct differences ccur for linked and adsorbed or mixed conjugates in the bsorption, infrared (IR) and Raman spectra and for thermal ravimetric decay profiles, suggesting successful formation f covalent bonds (linked) and point to structurally ifferent materials. SWCNT quench MPc fluorescence by a photoinduced electron transfer mediated process to give low fluorescence quantum yields. The QDs were used as energy transfer donors and facilitate energy transfer, through Förster resonance energy transfer (FRET) from the QDs to the MPcs. Improved FRET efficiencies were found for linked MPc-QD conjugates relative to the mixed species. Photophysicochemical properties of MPcs were, in general, improved as a result of interactions with nanoparticles.
- Full Text:
- Date Issued: 2010
Discursive constructions of quality assurance: the case of the Zimbabwe Council for Higher Education
- Authors: Chidindi, Joseph
- Date: 2017
- Subjects: Zimbabwe Council for Higher Education -- Evaluation , Education, Higher -- Zimbabwe , Universities and colleges -- Evaluation -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7800 , vital:21299
- Description: Quality assurance is on the contemporary agenda in higher education and has been prioritised across the globe. It has been conspicuous through the emergence of numerous quality assurance bodies, and in Zimbabwe, where this study takes place, the government has constituted the Zimbabwe Council for Higher Education. This study aims to identify the discourses drawn on by academics and those working within Zimbabwe Council for Higher Education to construct the roles and processes of external quality assurance practices in universities in Zimbabwe. The study was grounded on the premise that external quality assurance processes in higher education can vary according to their contextual environment. Fairclough’s Critical Discourse Analysis as a method driven theory not only provided a methodology, a way of collecting and analysing my data, but it was also a substantive theory, which provided a particular way of understanding the world through discourse. Fairclough’s Critical Discourse Analysis is grounded in a Critical Realist view of the social world that enabled generalisations about the effect discourse was having on the phenomenon of interest: quality assurance in higher education. One-to-one and group interviews were used to yield exploratory, descriptive and explanatory data. To corroborate and augment data from interviews, key documents related to quality assurance in universities in Zimbabwe and obtained from the Zimbabwe Council for Higher Education were analysed. There were a number of profound discourses that emerged in the research study. There was a discourse of ‘control’ in which Zimbabwe Council for Higher Education put in place compliance mechanisms, setting minimum requirements for universities to offer ‘credible’ higher education. There was a discourse of ‘power struggle’ in which universities endeavoured to maintain their institutional autonomy in response to what was perceived as Zimbabwe Council for Higher Education’s requirement of compliance. In the context of higher education in Zimbabwe, an important implication of the study was evident in the discourse of ‘gold standard’ of quality assurance which assumed that quality entails a generic best practice but which fails to take context into account. While a generic ‘global’ notion of best practice in quality assurance was dominant in the discourses of quality identified in this study, there were other discourses that focused on what quality might look like within the resource constraints of the context. The study highlighted the importance of collegiality between quality assurance organisations and universities to realise success of quality assurance intentions.
- Full Text:
- Date Issued: 2017
Discursive constructions of quality assurance: the case of the Zimbabwe Council for Higher Education
- Authors: Chidindi, Joseph
- Date: 2017
- Subjects: Zimbabwe Council for Higher Education -- Evaluation , Education, Higher -- Zimbabwe , Universities and colleges -- Evaluation -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7800 , vital:21299
- Description: Quality assurance is on the contemporary agenda in higher education and has been prioritised across the globe. It has been conspicuous through the emergence of numerous quality assurance bodies, and in Zimbabwe, where this study takes place, the government has constituted the Zimbabwe Council for Higher Education. This study aims to identify the discourses drawn on by academics and those working within Zimbabwe Council for Higher Education to construct the roles and processes of external quality assurance practices in universities in Zimbabwe. The study was grounded on the premise that external quality assurance processes in higher education can vary according to their contextual environment. Fairclough’s Critical Discourse Analysis as a method driven theory not only provided a methodology, a way of collecting and analysing my data, but it was also a substantive theory, which provided a particular way of understanding the world through discourse. Fairclough’s Critical Discourse Analysis is grounded in a Critical Realist view of the social world that enabled generalisations about the effect discourse was having on the phenomenon of interest: quality assurance in higher education. One-to-one and group interviews were used to yield exploratory, descriptive and explanatory data. To corroborate and augment data from interviews, key documents related to quality assurance in universities in Zimbabwe and obtained from the Zimbabwe Council for Higher Education were analysed. There were a number of profound discourses that emerged in the research study. There was a discourse of ‘control’ in which Zimbabwe Council for Higher Education put in place compliance mechanisms, setting minimum requirements for universities to offer ‘credible’ higher education. There was a discourse of ‘power struggle’ in which universities endeavoured to maintain their institutional autonomy in response to what was perceived as Zimbabwe Council for Higher Education’s requirement of compliance. In the context of higher education in Zimbabwe, an important implication of the study was evident in the discourse of ‘gold standard’ of quality assurance which assumed that quality entails a generic best practice but which fails to take context into account. While a generic ‘global’ notion of best practice in quality assurance was dominant in the discourses of quality identified in this study, there were other discourses that focused on what quality might look like within the resource constraints of the context. The study highlighted the importance of collegiality between quality assurance organisations and universities to realise success of quality assurance intentions.
- Full Text:
- Date Issued: 2017
Integrating sustainability principles in construction health and safety management practices in Zimbabwe
- Authors: Chigara, Benviolent
- Date: 2018
- Subjects: Sustainable construction -- Zimbabwe , Construction industry -- Safety measures Industrial safety -- Zimbabwe -- Management
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/23459 , vital:30565
- Description: The construction industry is an important industry to national development through the provision of infrastructure and creation of employment, and hence contributing to sustainable development. Nevertheless, the construction industry has a poor health and safety (H&S) and environmental record. Globally, the construction industry is a leading contributor to workplace fatalities, injuries, and disease. In Zimbabwe, the Millennium Towers accident, which resulted in 15 construction workers losing their lives, compromised the integrity of construction H&S management, and highlighted the need to improve H&S management in the sector. This study examined H&S management in Zimbabwe and developed a framework for integrating sustainability into H&S management practices. The study employed a mixed method research design involving the use of interviews and questionnaires to collect primary data from contractors, consultants, government, clients, and workers in Harare and Bulawayo. A total of 101 questionnaires were successfully completed and analysed, representing a response rate of 55.6%. The data from questionnaires were analysed with the help of the SPSS software v.23 to produce descriptive and inferential statistics. The results of the study suggest that H&S practices are inadequate as demonstrated by the extent to which workers are exposed to hazards and the occurrence of injuries, disease, and fatalities. The factors contributing to workers’ exposure to hazards and the occurrence of injuries, disease, and fatalities include, inter alia, inadequate planning for H&S, inadequate hazard identification and risk assessments (HIRAs), inadequate management of hazards, inadequate occupational health (OH) surveillance, appointment of stakeholders who do not systematically manage H&S, inadequate design HIRAs, and unsafe work practices. The problem is amplified by inadequate integration of H&S within procurement systems, which limit the extent to which contractors make financial provision for H&S. Regrettably, workplace fatalities, injuries, and disease diminish the quality of life for the injured workers, increase project cost and delays project completion. Against this background, the study investigated the integration of sustainability principles in construction H&S as a strategy to improve H&S practices in Zimbabwe. The outcome of that investigation was a strategy and interventions, and a framework for improved practices in the form of a Sustainability Framework for Construction H&S (SFCHS). The validation of the SFCHS by construction practitioners confirms the importance of the recommended practices to reducing workplace fatalities, injuries, and disease in Zimbabwe and beyond. The development of a SFCHS, as a strategy to improve H&S practices in Zimbabwe, and the validation thereof, resulted in a significant contribution to the related body of knowledge. Nevertheless, the transition to sustainable H&S practices require contractors, consultants, government, clients and workers to take a proactive role relative to the recommended practices in the SFCHS. Further studies can explore the responsiveness of sustainability factors relative to the occurrence of injuries, disease and fatalities based on selected case studies.
- Full Text:
- Date Issued: 2018
- Authors: Chigara, Benviolent
- Date: 2018
- Subjects: Sustainable construction -- Zimbabwe , Construction industry -- Safety measures Industrial safety -- Zimbabwe -- Management
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/23459 , vital:30565
- Description: The construction industry is an important industry to national development through the provision of infrastructure and creation of employment, and hence contributing to sustainable development. Nevertheless, the construction industry has a poor health and safety (H&S) and environmental record. Globally, the construction industry is a leading contributor to workplace fatalities, injuries, and disease. In Zimbabwe, the Millennium Towers accident, which resulted in 15 construction workers losing their lives, compromised the integrity of construction H&S management, and highlighted the need to improve H&S management in the sector. This study examined H&S management in Zimbabwe and developed a framework for integrating sustainability into H&S management practices. The study employed a mixed method research design involving the use of interviews and questionnaires to collect primary data from contractors, consultants, government, clients, and workers in Harare and Bulawayo. A total of 101 questionnaires were successfully completed and analysed, representing a response rate of 55.6%. The data from questionnaires were analysed with the help of the SPSS software v.23 to produce descriptive and inferential statistics. The results of the study suggest that H&S practices are inadequate as demonstrated by the extent to which workers are exposed to hazards and the occurrence of injuries, disease, and fatalities. The factors contributing to workers’ exposure to hazards and the occurrence of injuries, disease, and fatalities include, inter alia, inadequate planning for H&S, inadequate hazard identification and risk assessments (HIRAs), inadequate management of hazards, inadequate occupational health (OH) surveillance, appointment of stakeholders who do not systematically manage H&S, inadequate design HIRAs, and unsafe work practices. The problem is amplified by inadequate integration of H&S within procurement systems, which limit the extent to which contractors make financial provision for H&S. Regrettably, workplace fatalities, injuries, and disease diminish the quality of life for the injured workers, increase project cost and delays project completion. Against this background, the study investigated the integration of sustainability principles in construction H&S as a strategy to improve H&S practices in Zimbabwe. The outcome of that investigation was a strategy and interventions, and a framework for improved practices in the form of a Sustainability Framework for Construction H&S (SFCHS). The validation of the SFCHS by construction practitioners confirms the importance of the recommended practices to reducing workplace fatalities, injuries, and disease in Zimbabwe and beyond. The development of a SFCHS, as a strategy to improve H&S practices in Zimbabwe, and the validation thereof, resulted in a significant contribution to the related body of knowledge. Nevertheless, the transition to sustainable H&S practices require contractors, consultants, government, clients and workers to take a proactive role relative to the recommended practices in the SFCHS. Further studies can explore the responsiveness of sustainability factors relative to the occurrence of injuries, disease and fatalities based on selected case studies.
- Full Text:
- Date Issued: 2018
Land Reform and the Challenge of Rural Development in Zimbabwe: The Case of the Fast Track Reform in Mashonaland West Region
- Authors: Chigarira, Tangai Sylvester
- Date: 2019
- Subjects: Land reform -- Zimbabwe Agriculture and state -- Zimbabwe Zimbabwe -- Politics and government
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/18665 , vital:42704
- Description: A largely agricultural country, land remains an important factor of production and a critical element in the livelihoods of rural Zimbabweans. Small-scale farmers rely on land for food and income. The post-independence development of Zimbabwe has been tied to land holding. As such, land reform aimed at addressing colonial racial land inequalities and rural underdevelopment became an imperative. In the post-independence era, Zimbabwe undertook two phases of land reform – the first occurred between 1980 and 1999 and was known as the Land reform and Resettlement Programme (LRRP). This was based on the ‘willing-buyer and willing seller’. The second phase which took place from 2000, known as the Fast Track Land Reform Programme (FTLRP), took a radical approach. However, due to a variety of reasons, including the dominance of small-scale farming and challenges of land reform, agricultural productivity remains low. Moreover, despite land reform, including massive land redistribution, the process appears incomplete and inconclusive. This is so essentially because the land reform neither increased food production nor reduced poverty. Accordingly, sustainable development remains a distant reality, especially among rural small-scale farmers. The study aimed at assessing the impact of the fast track land reform (FTLRP) on poverty reduction and sustainable rural development in Zimbabwe. Despite undertaking one of Southern Africa’s largest post-colonial redistributive land reform to date, the provision of land on its own has not been sufficient to address rural poverty and achieving meaningful rural development. This is so because the land reform has not articulated integrated growth as remoteness and poverty remain endemic, which is connected to the land. So, resolving the land question still remains crucial for sustainable rural development in Zimbabwe.
- Full Text:
- Date Issued: 2019
- Authors: Chigarira, Tangai Sylvester
- Date: 2019
- Subjects: Land reform -- Zimbabwe Agriculture and state -- Zimbabwe Zimbabwe -- Politics and government
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/18665 , vital:42704
- Description: A largely agricultural country, land remains an important factor of production and a critical element in the livelihoods of rural Zimbabweans. Small-scale farmers rely on land for food and income. The post-independence development of Zimbabwe has been tied to land holding. As such, land reform aimed at addressing colonial racial land inequalities and rural underdevelopment became an imperative. In the post-independence era, Zimbabwe undertook two phases of land reform – the first occurred between 1980 and 1999 and was known as the Land reform and Resettlement Programme (LRRP). This was based on the ‘willing-buyer and willing seller’. The second phase which took place from 2000, known as the Fast Track Land Reform Programme (FTLRP), took a radical approach. However, due to a variety of reasons, including the dominance of small-scale farming and challenges of land reform, agricultural productivity remains low. Moreover, despite land reform, including massive land redistribution, the process appears incomplete and inconclusive. This is so essentially because the land reform neither increased food production nor reduced poverty. Accordingly, sustainable development remains a distant reality, especially among rural small-scale farmers. The study aimed at assessing the impact of the fast track land reform (FTLRP) on poverty reduction and sustainable rural development in Zimbabwe. Despite undertaking one of Southern Africa’s largest post-colonial redistributive land reform to date, the provision of land on its own has not been sufficient to address rural poverty and achieving meaningful rural development. This is so because the land reform has not articulated integrated growth as remoteness and poverty remain endemic, which is connected to the land. So, resolving the land question still remains crucial for sustainable rural development in Zimbabwe.
- Full Text:
- Date Issued: 2019
Electrospun nanofibers : an alternative sorbent material for solid phase extraction
- Chigome, Samuel, Samuel Chigome
- Authors: Chigome, Samuel , Samuel Chigome
- Date: 2012 , 2012-03-26
- Subjects: Nanofibers -- Research Electrospinning -- Research Sorbents -- Research Extraction (Chemistry) -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4314 , http://hdl.handle.net/10962/d1004972
- Description: The work described in the thesis seeks to lay a foundation for a better understanding of the use of electrospun nanofibers as a sorbent material. Three miniaturised electrospun nanofiber based solid phase extraction devices were fabricated. For the first two, 10 mg of electrospun polystyrene fibers were used as a sorbent bed for a micro column SPE device (8 mm bed height in a 200 μl pipette tip) and a disk (I) SPE device (5 mm 1 mm sorbent bed in a 1000 μl SPE barrel). While for the third, 4.6 mg of electrospun nylon nanofibers were used as a sorbent bed for a disk (II) SPE device, (sorbent bed consisting of 5 5 mm 350 μm stacked disks in a 500 μl SPE barrel). Corticosteroids were employed as model analytes for performance evaluation of the fabricated SPE devices. Quantitative recoveries (45.5-124.29 percent) were achieved for all SPE devices at a loading volume of 100 μl and analyte concentration of 500 ng ml-1. Three mathematical models; the Boltzmann, Weibull five parameter and the Sigmoid three parameter were employed to describe the break through profiles of each of the sorbent beds. The micro column SPE device exhibited a breakthrough volume of 1400 μl, and theoretical plates (7.98-9.1) while disk (I) SPE device exhibited 400-500 μl and 1.39-2.82 respectively. Disk (II) SPE device exhibited a breakthrough volume of 200 μl and theoretical plates 0.38-1.15. It was proposed that the formats of future electrospun nanofiber sorbent based SPE devices will be guided by mechanical strength of the polymer. The study classified electrospun polymer fibers into two as polystyrene type (relatively low mechanical strength) and nylon type (relatively high mechanical strength).
- Full Text:
- Date Issued: 2012
- Authors: Chigome, Samuel , Samuel Chigome
- Date: 2012 , 2012-03-26
- Subjects: Nanofibers -- Research Electrospinning -- Research Sorbents -- Research Extraction (Chemistry) -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4314 , http://hdl.handle.net/10962/d1004972
- Description: The work described in the thesis seeks to lay a foundation for a better understanding of the use of electrospun nanofibers as a sorbent material. Three miniaturised electrospun nanofiber based solid phase extraction devices were fabricated. For the first two, 10 mg of electrospun polystyrene fibers were used as a sorbent bed for a micro column SPE device (8 mm bed height in a 200 μl pipette tip) and a disk (I) SPE device (5 mm 1 mm sorbent bed in a 1000 μl SPE barrel). While for the third, 4.6 mg of electrospun nylon nanofibers were used as a sorbent bed for a disk (II) SPE device, (sorbent bed consisting of 5 5 mm 350 μm stacked disks in a 500 μl SPE barrel). Corticosteroids were employed as model analytes for performance evaluation of the fabricated SPE devices. Quantitative recoveries (45.5-124.29 percent) were achieved for all SPE devices at a loading volume of 100 μl and analyte concentration of 500 ng ml-1. Three mathematical models; the Boltzmann, Weibull five parameter and the Sigmoid three parameter were employed to describe the break through profiles of each of the sorbent beds. The micro column SPE device exhibited a breakthrough volume of 1400 μl, and theoretical plates (7.98-9.1) while disk (I) SPE device exhibited 400-500 μl and 1.39-2.82 respectively. Disk (II) SPE device exhibited a breakthrough volume of 200 μl and theoretical plates 0.38-1.15. It was proposed that the formats of future electrospun nanofiber sorbent based SPE devices will be guided by mechanical strength of the polymer. The study classified electrospun polymer fibers into two as polystyrene type (relatively low mechanical strength) and nylon type (relatively high mechanical strength).
- Full Text:
- Date Issued: 2012
An investigation of parameter relationships in a high-speed digital multimedia environment
- Authors: Chigwamba, Nyasha
- Date: 2014
- Subjects: Multimedia communications , Digital communications , Local area networks (Computer networks) , Computer network architectures , Computer network protocols , Computer sound processing , Sound -- Recording and reproducing -- Digital techniques
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4725 , http://hdl.handle.net/10962/d1021153
- Description: With the rapid adoption of multimedia network technologies, a number of companies and standards bodies are introducing technologies that enhance user experience in networked multimedia environments. These technologies focus on device discovery, connection management, control, and monitoring. This study focused on control and monitoring. Multimedia networks make it possible for devices that are part of the same network to reside in different physical locations. These devices contain parameters that are used to control particular features, such as speaker volume, bass, amplifier gain, and video resolution. It is often necessary for changes in one parameter to affect other parameters, such as a synchronised change between volume and bass parameters, or collective control of multiple parameters. Thus, relationships are required between the parameters. In addition, some devices contain parameters, such as voltage, temperature, and audio level, that require constant monitoring to enable corrective action when thresholds are exceeded. Therefore, a mechanism for monitoring networked devices is required. This thesis proposes relationships that are essential for the proper functioning of a multimedia network and that should, therefore, be incorporated in standard form into a protocol, such that all devices can depend on them. Implementation mechanisms for these relationships were created. Parameter grouping and monitoring capabilities within mixing console implementations and existing control protocols were reviewed. A number of requirements for parameter grouping and monitoring were derived from this review. These requirements include a formal classification of relationship types, the ability to create relationships between parameters with different underlying value units, the ability to create relationships between parameters residing on different devices on a network, and the use of an event-driven mechanism for parameter monitoring. These requirements were the criteria used to govern the implementation mechanisms that were created as part of this study. Parameter grouping and monitoring mechanisms were implemented for the XFN protocol. The mechanisms implemented fulfil the requirements derived from the review of capabilities of mixing consoles and existing control protocols. The formal classification of relationship types was implemented within XFN parameters using lists that keep track of the relationships between each XFN parameter and other XFN parameters that reside on the same device or on other devices on the network. A common value unit, known as the global unit, was defined for use as the value format within value update messages between XFN parameters that have relationships. Mapping tables were used to translate the global unit values to application-specific (universal) units, such as decibels (dB). A mechanism for bulk parameter retrieval within the XFN protocol was augmented to produce an event-driven mechanism for parameter monitoring. These implementation mechanisms were applied to an XFN-protocol-compliant graphical control application to demonstrate their usage within an end user context. At the time of this study, the XFN protocol was undergoing standardisation within the Audio Engineering Society. The AES-64 standard has now been approved. Most of the implementation mechanisms resulting from this study have been incorporated into this standard.
- Full Text:
- Date Issued: 2014
- Authors: Chigwamba, Nyasha
- Date: 2014
- Subjects: Multimedia communications , Digital communications , Local area networks (Computer networks) , Computer network architectures , Computer network protocols , Computer sound processing , Sound -- Recording and reproducing -- Digital techniques
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4725 , http://hdl.handle.net/10962/d1021153
- Description: With the rapid adoption of multimedia network technologies, a number of companies and standards bodies are introducing technologies that enhance user experience in networked multimedia environments. These technologies focus on device discovery, connection management, control, and monitoring. This study focused on control and monitoring. Multimedia networks make it possible for devices that are part of the same network to reside in different physical locations. These devices contain parameters that are used to control particular features, such as speaker volume, bass, amplifier gain, and video resolution. It is often necessary for changes in one parameter to affect other parameters, such as a synchronised change between volume and bass parameters, or collective control of multiple parameters. Thus, relationships are required between the parameters. In addition, some devices contain parameters, such as voltage, temperature, and audio level, that require constant monitoring to enable corrective action when thresholds are exceeded. Therefore, a mechanism for monitoring networked devices is required. This thesis proposes relationships that are essential for the proper functioning of a multimedia network and that should, therefore, be incorporated in standard form into a protocol, such that all devices can depend on them. Implementation mechanisms for these relationships were created. Parameter grouping and monitoring capabilities within mixing console implementations and existing control protocols were reviewed. A number of requirements for parameter grouping and monitoring were derived from this review. These requirements include a formal classification of relationship types, the ability to create relationships between parameters with different underlying value units, the ability to create relationships between parameters residing on different devices on a network, and the use of an event-driven mechanism for parameter monitoring. These requirements were the criteria used to govern the implementation mechanisms that were created as part of this study. Parameter grouping and monitoring mechanisms were implemented for the XFN protocol. The mechanisms implemented fulfil the requirements derived from the review of capabilities of mixing consoles and existing control protocols. The formal classification of relationship types was implemented within XFN parameters using lists that keep track of the relationships between each XFN parameter and other XFN parameters that reside on the same device or on other devices on the network. A common value unit, known as the global unit, was defined for use as the value format within value update messages between XFN parameters that have relationships. Mapping tables were used to translate the global unit values to application-specific (universal) units, such as decibels (dB). A mechanism for bulk parameter retrieval within the XFN protocol was augmented to produce an event-driven mechanism for parameter monitoring. These implementation mechanisms were applied to an XFN-protocol-compliant graphical control application to demonstrate their usage within an end user context. At the time of this study, the XFN protocol was undergoing standardisation within the Audio Engineering Society. The AES-64 standard has now been approved. Most of the implementation mechanisms resulting from this study have been incorporated into this standard.
- Full Text:
- Date Issued: 2014
Towards intercultural communication congruence in Sino-African organisational contexts
- Authors: Chigwendere, Fungai Beaula
- Date: 2018
- Subjects: Intercultural communication -- Africa , China -- Foreign economic relations -- Africa , Communication in organizations -- Cross-cultural studies , Corporate culture -- Cross-cultural studies , Africa -- Relations -- China , China -- Relations -- Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62395 , vital:28172
- Description: Despite the prevalence of theories and research that could serve as guidelines for addressing intercultural communication challenges such as misunderstanding, ineffectiveness and inappropriateness in communication in Sino-African organisational contexts, the continued existence of these challenges suggests the inadequacy of such theories. Accordingly, in consideration of African and Chinese cultural perspectives, the aim of this study was to develop a hybrid intercultural communication congruence (HICC) framework in order to enhance intercultural communication and achieve intercultural communication congruence in Sino-African organisational contexts. In this study, intercultural communication congruence means effectiveness and appropriateness in intercultural communication. To achieve the study aim, an interpretive pragmatism paradigm was adopted, comprising a two-pronged approach of a synthesis of extant literature and theory as well as an empirical qualitative study, both underpinned by cross-cultural management theory. Based on the synthesis of literature and theory, a generic theoretical intercultural communication congruence framework underpinned by intercultural communication awareness - a state where communicants understand communication orientation and manner of communication in their own and their counterparts’ culture - was developed. A further contribution was a theoretical contextualisation of the generic theoretical intercultural communication congruence framework, resulting in a theoretical framework for intercultural communication awareness in Western, African and Chinese cultures and a theoretical intercultural communication congruence framework specific to Sino-African organisational contexts. Thereafter, with the aim of validating the intercultural communication awareness dimension of the theoretical intercultural communication congruence framework specific to Sino-African organisational contexts, an empirical study was conducted with a sample of seven African and eight Chinese experts using indepth interviews with open-ended and semi-structured questions. Based on qualitative content analysis, six intercultural communication awareness enablers or conditions that enable people to understand communication in different cultures and contexts for the purposes of attaining intercultural communication awareness emerged. These were cultural orientation, manner of communication, orientation to rules and protocol, individual dispositions, intercultural communication influences and intercultural communication variations. An integration of the intercultural communication awareness enablers into the generic theoretical intercultural communication congruence framework results in an updated generic theoretical intercultural communication congruence framework. Then, informed by the updated generic theoretical intercultural communication congruence framework, a further contribution of this study was an empirical verification of the intercultural communication awareness dimension of the theoretical intercultural communication congruence framework specific to Sino-African organisational contexts to result in a final hybrid intercultural communication congruence framework for Sino-African organisational contexts supported by the perspectives of those involved in interaction, rather than predetermined standards of other cultures. Empirical findings suggest that both African and Chinese colleagues maintain a sense of collectivism in the Sino- African organisational context, although this is demonstrated differently. In addition, African colleagues display a blended manner of communication characterised by a mix of Western and African ways while the Chinese manner is contextual and governed by roles and relationships. In African culture, rules and protocol are negotiated, aimed at social maintenance, while strong cultural patriotism ensures strict adherence in Chinese culture. In respect of individual dispositions, African people are seen as open and accommodating while the Chinese disposition could be described as closed and ambiguous. Also evident in the findings is the existence of within-culture differences and influence of noncultural factors on intercultural communication that should be addressed in order to achieve intercultural communication congruence. Finally, the frameworks developed and the methodological processes followed will stimulate academic debate and raise numerous questions for future research. Immediate future research could be geared towards refining the concepts of intercultural communication awareness, intercultural communication congruence and the hybrid intercultural communication congruence framework for Sino-African organisational contexts. At a management practice level, intercultural communication awareness insights provide a reference point for intercultural communication enhancement strategies and interventions in Sino-African organisational contexts.
- Full Text:
- Date Issued: 2018
- Authors: Chigwendere, Fungai Beaula
- Date: 2018
- Subjects: Intercultural communication -- Africa , China -- Foreign economic relations -- Africa , Communication in organizations -- Cross-cultural studies , Corporate culture -- Cross-cultural studies , Africa -- Relations -- China , China -- Relations -- Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62395 , vital:28172
- Description: Despite the prevalence of theories and research that could serve as guidelines for addressing intercultural communication challenges such as misunderstanding, ineffectiveness and inappropriateness in communication in Sino-African organisational contexts, the continued existence of these challenges suggests the inadequacy of such theories. Accordingly, in consideration of African and Chinese cultural perspectives, the aim of this study was to develop a hybrid intercultural communication congruence (HICC) framework in order to enhance intercultural communication and achieve intercultural communication congruence in Sino-African organisational contexts. In this study, intercultural communication congruence means effectiveness and appropriateness in intercultural communication. To achieve the study aim, an interpretive pragmatism paradigm was adopted, comprising a two-pronged approach of a synthesis of extant literature and theory as well as an empirical qualitative study, both underpinned by cross-cultural management theory. Based on the synthesis of literature and theory, a generic theoretical intercultural communication congruence framework underpinned by intercultural communication awareness - a state where communicants understand communication orientation and manner of communication in their own and their counterparts’ culture - was developed. A further contribution was a theoretical contextualisation of the generic theoretical intercultural communication congruence framework, resulting in a theoretical framework for intercultural communication awareness in Western, African and Chinese cultures and a theoretical intercultural communication congruence framework specific to Sino-African organisational contexts. Thereafter, with the aim of validating the intercultural communication awareness dimension of the theoretical intercultural communication congruence framework specific to Sino-African organisational contexts, an empirical study was conducted with a sample of seven African and eight Chinese experts using indepth interviews with open-ended and semi-structured questions. Based on qualitative content analysis, six intercultural communication awareness enablers or conditions that enable people to understand communication in different cultures and contexts for the purposes of attaining intercultural communication awareness emerged. These were cultural orientation, manner of communication, orientation to rules and protocol, individual dispositions, intercultural communication influences and intercultural communication variations. An integration of the intercultural communication awareness enablers into the generic theoretical intercultural communication congruence framework results in an updated generic theoretical intercultural communication congruence framework. Then, informed by the updated generic theoretical intercultural communication congruence framework, a further contribution of this study was an empirical verification of the intercultural communication awareness dimension of the theoretical intercultural communication congruence framework specific to Sino-African organisational contexts to result in a final hybrid intercultural communication congruence framework for Sino-African organisational contexts supported by the perspectives of those involved in interaction, rather than predetermined standards of other cultures. Empirical findings suggest that both African and Chinese colleagues maintain a sense of collectivism in the Sino- African organisational context, although this is demonstrated differently. In addition, African colleagues display a blended manner of communication characterised by a mix of Western and African ways while the Chinese manner is contextual and governed by roles and relationships. In African culture, rules and protocol are negotiated, aimed at social maintenance, while strong cultural patriotism ensures strict adherence in Chinese culture. In respect of individual dispositions, African people are seen as open and accommodating while the Chinese disposition could be described as closed and ambiguous. Also evident in the findings is the existence of within-culture differences and influence of noncultural factors on intercultural communication that should be addressed in order to achieve intercultural communication congruence. Finally, the frameworks developed and the methodological processes followed will stimulate academic debate and raise numerous questions for future research. Immediate future research could be geared towards refining the concepts of intercultural communication awareness, intercultural communication congruence and the hybrid intercultural communication congruence framework for Sino-African organisational contexts. At a management practice level, intercultural communication awareness insights provide a reference point for intercultural communication enhancement strategies and interventions in Sino-African organisational contexts.
- Full Text:
- Date Issued: 2018
An exploration of how consistently and precisely mathematics teachers code-switch in multilingual classrooms
- Authors: Chikiwa, Clemence
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2076 , http://hdl.handle.net/10962/d1021304
- Description: Many education research studies conducted in and outside South Africa encourage teachers to take advantage of the presence of multilingualism in their classrooms and to use it to the advancement of students’ conceptual learning. This study adopts the notion that code switching is a potential resource that teachers can use when teaching multilingual mathematics classes. The aim of this study is to determine how precisely and consistently selected teachers of multilingual mathematics classes code switched during teaching of trigonometry and geometry at secondary school. This study is informed by socio-cultural theory in general and Vygotsky’s work in particular. It focussed specifically on the critical role that language plays in the teaching and cognitive development of mathematics. My study situated within an interpretivist paradigm, used a case study research design and a mixed method research approach. Data were obtained through document collection, observing and interviewing three Grade 11 Mathematics teachers purposively selected from three secondary schools in Grahamstown and King Williamstown education districts of the Eastern Cape Province, South Africa. Data were quantitatively and qualitatively analysed. Findings from this study revealed that the frequency of code switching was not consistent across teachers, topics and lessons. Teachers taught predominantly in the public domain exposing students to compromised mathematical content through their code switching practices. Borrowing code switching was prevalently employed consistently across the participating teachers. Very little transparent code switching, from mainly those mathematical terms commonly used in the foundation and the intermediate phases, was evident in teacher language. No Grade 11 trigonometry and geometry terms in isiXhosa were transparently and consistently code switched. The data suggested that while precision was observed in some cases, it was not consistent. Inconsistencies were caused by lack of planning for code switching, lack of teaching materials in indigenous languages, selective code switching, and ‘safe mode’ code switching strategies which affected teachers’ pedagogical practices. Overall results in this study illustrate that the lack of planning for code switching and the lack of explicit policies and clear-cut official positions on code switching for teaching has contributed to inconsistent and imprecise code switching by the participating teachers. This study concludes that the development of supporting mechanisms, identifying and documenting best practices to encourage transparent, meaningful and beneficial code switching is urgently required to aid and promote conceptual understanding of strongly bounded sub-registers of secondary school mathematics such as trigonometry and geometry. It is anticipated that this study will contribute significantly to the ongoing debate on language use in education and to the institution of best practices for judicious, consistent and precise use of students’ home language during the teaching of mathematics in South Africa.
- Full Text:
- Date Issued: 2016
- Authors: Chikiwa, Clemence
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2076 , http://hdl.handle.net/10962/d1021304
- Description: Many education research studies conducted in and outside South Africa encourage teachers to take advantage of the presence of multilingualism in their classrooms and to use it to the advancement of students’ conceptual learning. This study adopts the notion that code switching is a potential resource that teachers can use when teaching multilingual mathematics classes. The aim of this study is to determine how precisely and consistently selected teachers of multilingual mathematics classes code switched during teaching of trigonometry and geometry at secondary school. This study is informed by socio-cultural theory in general and Vygotsky’s work in particular. It focussed specifically on the critical role that language plays in the teaching and cognitive development of mathematics. My study situated within an interpretivist paradigm, used a case study research design and a mixed method research approach. Data were obtained through document collection, observing and interviewing three Grade 11 Mathematics teachers purposively selected from three secondary schools in Grahamstown and King Williamstown education districts of the Eastern Cape Province, South Africa. Data were quantitatively and qualitatively analysed. Findings from this study revealed that the frequency of code switching was not consistent across teachers, topics and lessons. Teachers taught predominantly in the public domain exposing students to compromised mathematical content through their code switching practices. Borrowing code switching was prevalently employed consistently across the participating teachers. Very little transparent code switching, from mainly those mathematical terms commonly used in the foundation and the intermediate phases, was evident in teacher language. No Grade 11 trigonometry and geometry terms in isiXhosa were transparently and consistently code switched. The data suggested that while precision was observed in some cases, it was not consistent. Inconsistencies were caused by lack of planning for code switching, lack of teaching materials in indigenous languages, selective code switching, and ‘safe mode’ code switching strategies which affected teachers’ pedagogical practices. Overall results in this study illustrate that the lack of planning for code switching and the lack of explicit policies and clear-cut official positions on code switching for teaching has contributed to inconsistent and imprecise code switching by the participating teachers. This study concludes that the development of supporting mechanisms, identifying and documenting best practices to encourage transparent, meaningful and beneficial code switching is urgently required to aid and promote conceptual understanding of strongly bounded sub-registers of secondary school mathematics such as trigonometry and geometry. It is anticipated that this study will contribute significantly to the ongoing debate on language use in education and to the institution of best practices for judicious, consistent and precise use of students’ home language during the teaching of mathematics in South Africa.
- Full Text:
- Date Issued: 2016
Liquidity risk management by Zimbabwean commercial banks
- Authors: Chikoko, Laurine
- Date: 2012
- Subjects: Liquidity (Economics) , Banks and banking -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9027 , http://hdl.handle.net/10948/d1020344
- Description: Macroeconomic and financial market developments in Zimbabwe since 2000 have led to an increase in many banks‟ overall exposure to liquidity risk. The thesis highlights the importance of understanding and building comprehensive liquidity frameworks as defenses against liquidity stress. This study explores liquidity and liquidity risk management practices as well as the linkages and factors that affected different types of liquidity in the Zimbabwean banking sector during the Zimbabwean dollar and multiple currency eras. The research sought to present a comprehensive analysis of Zimbabwean commercial banks‟ liquidity risk management in challenging operating environments. Two periods were selected: January 2000 to December 2008 (the Zimbabwean dollar era) and March 2009 to June 2011 (the multiple currency era). Explanatory and survey research designs were used. The study applied econometric modeling using panel regression analysis to identify the major determinants of liquidity risk for 15 commercial banks in Zimbabwe. The financing gap ratio was used as the proxy for liquidity risk. The first investigation was on liquidity risk determinants in the Zimbabwean dollar era. The econometric investigations revealed that an increase in capital adequacy reduced liquidity risk and that there was a positive relationship between size and bank illiquidity. Liquidity risk was also explained by spreads. Inflation was positively related to liquidity risk and was a significant explanatory variable. Non-performing loans were not significant in explaining commercial banks‟ illiquidity, which is contrary to expectations. The second investigation was on commercial banks‟ liquidity risk determinants in the multiple currency era by using panel monthly data. The results showed that capital adequacy had a significant negative relationship with liquidity risk. The size of the bank was significant and positively related to bank illiquidity. Unlike in the Zimbabwean dollar era, spreads were negatively related to bank liquidity risk. Again, non-performing loans were a significant explanatory variable. The reserve requirements ratio and inflation also influenced bank illiquidity in the multiple currency regime. In both investigations, robustness tests for the main findings were done with an alternative dependent variable to the financing gap ratio. To complement the econometric analysis, a survey was conducted using questionnaires and interviews for the same 15 commercial banks. Empirical analysis in this research showed that during the 2000-2008 era; (i) no liquidity risk management guidelines were issued by the Reserve Bank of Zimbabwe until 2007. Banks relied on internal efforts in managing liquidity risk (ii) Liquidity was managed daily by treasury (iii) The operating environment was challenging with high inflation rates, which led to high demand for cash withdrawals by depositors (iv) Locally owned banks were more exposed to liquidity risk as compared to the foreign owned banks (v) Major sources of funds were new deposits, retention of maturities, shareholders, interbank borrowings, offshore lines of credit and also banks relied on the Reserve Bank of Zimbabwe as the lender of last resort (vi) Financial markets were active and banks offered a wide range of products (vii) To manage liquidity from depositors, banks relied on cash reserves, calculating and analysing the withdrawal patterns. When faced with cash shortages, banks relied on the daily limits set by the Reserve Bank of Zimbabwe (viii) Banks were lending but when the challenges deepened, they lent less in advances and increased investment in government securities. (ix) Inflation had major effects on liquidity risk management as it affected demand deposit tenors, fixed term products, corporate sector deposit mobilisation, cost of funds and investment portfolios (x) The regulatory environment was not favourable with RBZ policy measures designed to arrest inflation having negative repercussions on banks` liquidity management (xi) Banks had no liquidity crisis management frameworks. During the multiple currency exchange rate system (i) Commercial banks had problems in sourcing funds. They were mainly funded by transitory deposits with little coming in from treasury activities, interbank activities and offshore lines of credit. There was no lender of last resort function by the Reserve Bank of Zimbabwe. (ii) Some banks were still struggling to raise the minimum capital requirements (iii) Commercial banks offered narrow product ranges to clients (iv) To manage liquidity demand from clients, banks relied on the cash reserve ratio, and calculated the patterns of withdrawal, while some banks communicated with corporate clients on withdrawal schedules. (v) Zimbabwe commercial banks resumed the lending activity after dollarisation. Locally owned banks were aggressive, while foreign owned banks took a passive stance. There were problems with non-performing loans, especially from corporate clients, which exposed many banks to liquidity risk. (vi) Liquidity risk management in Zimbabwe was still guided by the Reserve Bank of Zimbabwe Risk Management Guideline BSD-04, 2007. All banks had liquidity risk management policies and procedure manuals but some banks were not adhering to them. Banks also had liquidity risk limits in place but some violated them. Furthermore, some banks were not conducting stress tests. Although all banks had contingency plans in place, none were testing them. Specifically, the research study highlighted the potential sources of liquidity risk in the Zimbabwean dollar and multiple currency periods. Based on the results, the study recommends survival strategies for banks in managing liquidity risk in such environments. It proposes a comprehensive liquidity management framework that clearly identifies, measures and control liquidity risk consistent with bank-specific and the country‟s macroeconomic developments. The envisaged framework would assist banks in dealing with illiquidity in a manner that would be less disruptive and that could render any future crisis less painful. Of importance is the recommendation that the central bank might not need to be too strict or too relaxed, but be moderate in ensuring an enabling regulatory environment. This would help banks to manage liquidity risk and at the same time protect depositors in any challenging operating environment. In both the studied time periods, there were transitory deposits. Generally there is need to inculcate a savings culture in Zimbabwe.
- Full Text:
- Date Issued: 2012
- Authors: Chikoko, Laurine
- Date: 2012
- Subjects: Liquidity (Economics) , Banks and banking -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9027 , http://hdl.handle.net/10948/d1020344
- Description: Macroeconomic and financial market developments in Zimbabwe since 2000 have led to an increase in many banks‟ overall exposure to liquidity risk. The thesis highlights the importance of understanding and building comprehensive liquidity frameworks as defenses against liquidity stress. This study explores liquidity and liquidity risk management practices as well as the linkages and factors that affected different types of liquidity in the Zimbabwean banking sector during the Zimbabwean dollar and multiple currency eras. The research sought to present a comprehensive analysis of Zimbabwean commercial banks‟ liquidity risk management in challenging operating environments. Two periods were selected: January 2000 to December 2008 (the Zimbabwean dollar era) and March 2009 to June 2011 (the multiple currency era). Explanatory and survey research designs were used. The study applied econometric modeling using panel regression analysis to identify the major determinants of liquidity risk for 15 commercial banks in Zimbabwe. The financing gap ratio was used as the proxy for liquidity risk. The first investigation was on liquidity risk determinants in the Zimbabwean dollar era. The econometric investigations revealed that an increase in capital adequacy reduced liquidity risk and that there was a positive relationship between size and bank illiquidity. Liquidity risk was also explained by spreads. Inflation was positively related to liquidity risk and was a significant explanatory variable. Non-performing loans were not significant in explaining commercial banks‟ illiquidity, which is contrary to expectations. The second investigation was on commercial banks‟ liquidity risk determinants in the multiple currency era by using panel monthly data. The results showed that capital adequacy had a significant negative relationship with liquidity risk. The size of the bank was significant and positively related to bank illiquidity. Unlike in the Zimbabwean dollar era, spreads were negatively related to bank liquidity risk. Again, non-performing loans were a significant explanatory variable. The reserve requirements ratio and inflation also influenced bank illiquidity in the multiple currency regime. In both investigations, robustness tests for the main findings were done with an alternative dependent variable to the financing gap ratio. To complement the econometric analysis, a survey was conducted using questionnaires and interviews for the same 15 commercial banks. Empirical analysis in this research showed that during the 2000-2008 era; (i) no liquidity risk management guidelines were issued by the Reserve Bank of Zimbabwe until 2007. Banks relied on internal efforts in managing liquidity risk (ii) Liquidity was managed daily by treasury (iii) The operating environment was challenging with high inflation rates, which led to high demand for cash withdrawals by depositors (iv) Locally owned banks were more exposed to liquidity risk as compared to the foreign owned banks (v) Major sources of funds were new deposits, retention of maturities, shareholders, interbank borrowings, offshore lines of credit and also banks relied on the Reserve Bank of Zimbabwe as the lender of last resort (vi) Financial markets were active and banks offered a wide range of products (vii) To manage liquidity from depositors, banks relied on cash reserves, calculating and analysing the withdrawal patterns. When faced with cash shortages, banks relied on the daily limits set by the Reserve Bank of Zimbabwe (viii) Banks were lending but when the challenges deepened, they lent less in advances and increased investment in government securities. (ix) Inflation had major effects on liquidity risk management as it affected demand deposit tenors, fixed term products, corporate sector deposit mobilisation, cost of funds and investment portfolios (x) The regulatory environment was not favourable with RBZ policy measures designed to arrest inflation having negative repercussions on banks` liquidity management (xi) Banks had no liquidity crisis management frameworks. During the multiple currency exchange rate system (i) Commercial banks had problems in sourcing funds. They were mainly funded by transitory deposits with little coming in from treasury activities, interbank activities and offshore lines of credit. There was no lender of last resort function by the Reserve Bank of Zimbabwe. (ii) Some banks were still struggling to raise the minimum capital requirements (iii) Commercial banks offered narrow product ranges to clients (iv) To manage liquidity demand from clients, banks relied on the cash reserve ratio, and calculated the patterns of withdrawal, while some banks communicated with corporate clients on withdrawal schedules. (v) Zimbabwe commercial banks resumed the lending activity after dollarisation. Locally owned banks were aggressive, while foreign owned banks took a passive stance. There were problems with non-performing loans, especially from corporate clients, which exposed many banks to liquidity risk. (vi) Liquidity risk management in Zimbabwe was still guided by the Reserve Bank of Zimbabwe Risk Management Guideline BSD-04, 2007. All banks had liquidity risk management policies and procedure manuals but some banks were not adhering to them. Banks also had liquidity risk limits in place but some violated them. Furthermore, some banks were not conducting stress tests. Although all banks had contingency plans in place, none were testing them. Specifically, the research study highlighted the potential sources of liquidity risk in the Zimbabwean dollar and multiple currency periods. Based on the results, the study recommends survival strategies for banks in managing liquidity risk in such environments. It proposes a comprehensive liquidity management framework that clearly identifies, measures and control liquidity risk consistent with bank-specific and the country‟s macroeconomic developments. The envisaged framework would assist banks in dealing with illiquidity in a manner that would be less disruptive and that could render any future crisis less painful. Of importance is the recommendation that the central bank might not need to be too strict or too relaxed, but be moderate in ensuring an enabling regulatory environment. This would help banks to manage liquidity risk and at the same time protect depositors in any challenging operating environment. In both the studied time periods, there were transitory deposits. Generally there is need to inculcate a savings culture in Zimbabwe.
- Full Text:
- Date Issued: 2012
Formulation and characterisation of a combination captopril and hydrochlorothiazide microparticulate dosage form for paediatric use
- Chikukwa, Mellisa Tafadzwa Ruramai
- Authors: Chikukwa, Mellisa Tafadzwa Ruramai
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163216 , vital:41019 , doi:10.21504/10962/163216
- Description: Thesis (PhD)--Rhodes University, Pharmacy Faculty, Department of Pharmaceutics, 2020
- Full Text:
- Date Issued: 2020
- Authors: Chikukwa, Mellisa Tafadzwa Ruramai
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163216 , vital:41019 , doi:10.21504/10962/163216
- Description: Thesis (PhD)--Rhodes University, Pharmacy Faculty, Department of Pharmaceutics, 2020
- Full Text:
- Date Issued: 2020
Exploring and expanding capabilities, sustainability and gender justice in science teacher education : case studies in Zimbabwe and South Africa
- Authors: Chikunda, Charles
- Date: 2013 , 2013-08-30
- Subjects: Science teachers -- Training of -- South Africa -- Case studies Science teachers -- Training of -- Zimbabwe -- Case studies Mathematics teachers -- Training of -- South Africa -- Case studies Women in education -- South Africa -- Case studies Women in education -- Zimbabwe -- Case studies Environmental education -- Study and teaching -- Case studies Curriculum planning -- South Africa Curriculum planning -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1887 , http://hdl.handle.net/10962/d1006026
- Description: The focus of this study was to explore and expand capabilities, sustainability and gender justice in Science, Mathematics and Technical subjects (SMTs) in teacher education curriculum practices as a process of Education for Sustainable Development in two case studies in Zimbabwe and South Africa. The study begins by discussing gender and science education discourse, locating it within Education for Sustainable Development discourse. Through this nexus, the study was able to explore gender and sustainability responsiveness of the curriculum practices of teacher educators in Science, Mathematics and Technical subjects; scrutinise underlying mechanisms that affect (promote or constrain) gender and sustainability responsive curriculum practices; and understand if and how teacher education curriculum practices consider the functionings and capabilities of females in relation to increased socio-ecological risk in a Southern African context. Influenced by a curriculum transformation commitment, an expansive learning phase was conducted to promote gender and sustainability responsive pedagogies in teacher education curriculum practices. As shown in the study, the expansive learning processes resulted in (re)conceptualising the curriculum practices (object), analysis of contradictions and developing new ways of doing work. Drawing from the sensitising concepts of dialectics, reflexivity and agency, the study worked with the three theoretical approaches of Cultural Historical Activity Theory (CHAT), feminist theory and capabilities theory. The capability and feminist lenses were used in the exploration of gender and sustainability responsiveness in science teacher education curriculum practices. CHAT, through its associated methodology of Developmental Work Research, offered the opportunity for researcher and participants in this study to come together to question and analyse curriculum practices and model new ways of doing work. Case study research was used in two case studies of teacher education curriculum practices in Science, Mathematics and Technical subjects, one in Zimbabwe and one in South Africa. Each case study is constituted with a networked activity system. The study used in-depth and focus group interviews and document analysis to explore gender and sustainability responsiveness in curriculum practices and to generate mirror data. Inductive and abductive modes of inference, and Critical Discourse Analysis were used to analyse data. This data was then used in Change Laboratory Workshops, where double stimulation and focus group discussions contributed to the expansive learning process. Findings from the exploration phase of the study revealed that most teacher educators in the two case studies had some basic levels of gender sensitivity, meaning that they had ability to perceive existing gender inequalities as it applies only to gender disaggregated data especially when it comes to enrolment and retention. However, there was no institutionalised pedagogic device in place in both case studies aimed at equipping future teachers with knowledge, skills, attitudes and values to promote aspects of capabilities (well-being achievement, wellbeing freedom, agency achievement and agency freedom) for girls in Science, Mathematics and Technical subjects. Science, Mathematics and Technical subjects teacher educators' curriculum practices were gender neutral, but in a gendered environment. This was a pedagogical tension that was visible in both case studies. On the other hand, socio-ecological issues, in cases where they were incorporated into the curriculum, were incorporated in a gender blind or gender neutral manner. Social ecological concerns such as climate change were treated as if they were not gendered both in their impact and in their mitigation and adaptation. It emerged that causal mechanisms shaping this situation were of a socio-political nature: there exist cultural differences between students and teacher educators; patriarchal ideology and hegemony; as well as other interfering binaries such as race and class. Other curriculum related constraints, though embedded in the socio-cultural-political nexus, include: rigid and content heavy curriculum, coupled with students who come into the system with inadequate content knowledge; and philosophy informing pedagogy namely scientism, with associated instrumentalist and functionalist tenets. All these led to contradictions between pedagogical practices with those expected by the Education for Sustainable Development framework. The study contributes in-depth insight into science teacher education curriculum development. By locating the study at the nexus of gender and Science, Mathematics and Technical subjects within the Education for Sustainable Development discourse, using the ontological lenses of feminist and capabilities, it was possible to interrogate aspects of quality and relevance of the science teacher education curriculum. The study also provides insight into participatory research and learning processes especially within the context of policy and curriculum development. It provides empirical evidence of mobilising reflexivity amongst both policy makers and policy implementers towards building human agency in policy translation for a curriculum transformation that is critical for responding to contemporary socio-ecological risks. , Microsoft� Word 2010 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
- Authors: Chikunda, Charles
- Date: 2013 , 2013-08-30
- Subjects: Science teachers -- Training of -- South Africa -- Case studies Science teachers -- Training of -- Zimbabwe -- Case studies Mathematics teachers -- Training of -- South Africa -- Case studies Women in education -- South Africa -- Case studies Women in education -- Zimbabwe -- Case studies Environmental education -- Study and teaching -- Case studies Curriculum planning -- South Africa Curriculum planning -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1887 , http://hdl.handle.net/10962/d1006026
- Description: The focus of this study was to explore and expand capabilities, sustainability and gender justice in Science, Mathematics and Technical subjects (SMTs) in teacher education curriculum practices as a process of Education for Sustainable Development in two case studies in Zimbabwe and South Africa. The study begins by discussing gender and science education discourse, locating it within Education for Sustainable Development discourse. Through this nexus, the study was able to explore gender and sustainability responsiveness of the curriculum practices of teacher educators in Science, Mathematics and Technical subjects; scrutinise underlying mechanisms that affect (promote or constrain) gender and sustainability responsive curriculum practices; and understand if and how teacher education curriculum practices consider the functionings and capabilities of females in relation to increased socio-ecological risk in a Southern African context. Influenced by a curriculum transformation commitment, an expansive learning phase was conducted to promote gender and sustainability responsive pedagogies in teacher education curriculum practices. As shown in the study, the expansive learning processes resulted in (re)conceptualising the curriculum practices (object), analysis of contradictions and developing new ways of doing work. Drawing from the sensitising concepts of dialectics, reflexivity and agency, the study worked with the three theoretical approaches of Cultural Historical Activity Theory (CHAT), feminist theory and capabilities theory. The capability and feminist lenses were used in the exploration of gender and sustainability responsiveness in science teacher education curriculum practices. CHAT, through its associated methodology of Developmental Work Research, offered the opportunity for researcher and participants in this study to come together to question and analyse curriculum practices and model new ways of doing work. Case study research was used in two case studies of teacher education curriculum practices in Science, Mathematics and Technical subjects, one in Zimbabwe and one in South Africa. Each case study is constituted with a networked activity system. The study used in-depth and focus group interviews and document analysis to explore gender and sustainability responsiveness in curriculum practices and to generate mirror data. Inductive and abductive modes of inference, and Critical Discourse Analysis were used to analyse data. This data was then used in Change Laboratory Workshops, where double stimulation and focus group discussions contributed to the expansive learning process. Findings from the exploration phase of the study revealed that most teacher educators in the two case studies had some basic levels of gender sensitivity, meaning that they had ability to perceive existing gender inequalities as it applies only to gender disaggregated data especially when it comes to enrolment and retention. However, there was no institutionalised pedagogic device in place in both case studies aimed at equipping future teachers with knowledge, skills, attitudes and values to promote aspects of capabilities (well-being achievement, wellbeing freedom, agency achievement and agency freedom) for girls in Science, Mathematics and Technical subjects. Science, Mathematics and Technical subjects teacher educators' curriculum practices were gender neutral, but in a gendered environment. This was a pedagogical tension that was visible in both case studies. On the other hand, socio-ecological issues, in cases where they were incorporated into the curriculum, were incorporated in a gender blind or gender neutral manner. Social ecological concerns such as climate change were treated as if they were not gendered both in their impact and in their mitigation and adaptation. It emerged that causal mechanisms shaping this situation were of a socio-political nature: there exist cultural differences between students and teacher educators; patriarchal ideology and hegemony; as well as other interfering binaries such as race and class. Other curriculum related constraints, though embedded in the socio-cultural-political nexus, include: rigid and content heavy curriculum, coupled with students who come into the system with inadequate content knowledge; and philosophy informing pedagogy namely scientism, with associated instrumentalist and functionalist tenets. All these led to contradictions between pedagogical practices with those expected by the Education for Sustainable Development framework. The study contributes in-depth insight into science teacher education curriculum development. By locating the study at the nexus of gender and Science, Mathematics and Technical subjects within the Education for Sustainable Development discourse, using the ontological lenses of feminist and capabilities, it was possible to interrogate aspects of quality and relevance of the science teacher education curriculum. The study also provides insight into participatory research and learning processes especially within the context of policy and curriculum development. It provides empirical evidence of mobilising reflexivity amongst both policy makers and policy implementers towards building human agency in policy translation for a curriculum transformation that is critical for responding to contemporary socio-ecological risks. , Microsoft� Word 2010 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
Estuarine-dependency and multiple habitat use by dusky kob Argyrosomus Japonicus (Pisces: Sciaenidae)
- Authors: Childs, Amber-Robyn
- Date: 2013
- Subjects: Argyrosomus -- Habitat -- South Africa -- Algoa Bay , Argyrosomus -- Behavior -- South Africa -- Algoa Bay , Argyrosomus -- Migration -- South Africa -- Algoa Bay , Estuarine fishes -- South Africa -- Algoa Bay , Habitat selection -- South Africa -- Algoa Bay , Argyrosomus -- South Africa -- Sundays Estuary (Eastern Cape) , Underwater acoustic telemetry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5386 , http://hdl.handle.net/10962/d1020241
- Description: Dusky kob Argyrosomus japonicus is a wide-ranging estuarine-dependent Sciaenid and an important fishery species throughout most of its distribution. It is one of South Africa’s most valuable coastal fishery species. High levels of juvenile exploitation in estuaries and ineffective management regulations have led to stock collapse, highlighting the need to better understand the spatial and temporal aspects of estuarine-dependency and multiple habitat use. Habitat connectivity is a critical property of estuarine-associated fishes and it therefore follows that knowledge of this link is fundamental in understanding population dynamics and the nursery role of estuarine and/or marine habitats. While dusky kob occur in both estuaries and nearshore coastal zones, limited information on connectivity among these habitats exists. The aim of this study is to assess the role of estuarine nursery habitats in the life cycle of the dusky kob by examining multiple habitat connectivity and determining the drivers associated with estuarine use. A total of 96 dusky kob (237–1280 mm total length) were tagged with acoustic transmitters in both the estuarine and marine environments of Algoa Bay, Eastern Cape, South Africa between May 2008 and September 2010. Their movements were monitored using a network of automated data-logging acoustic receivers deployed in the Sundays Estuary, seven neighbouring estuarine habitats, two commercial harbours and various sites within Algoa Bay. And more...
- Full Text:
- Date Issued: 2013
- Authors: Childs, Amber-Robyn
- Date: 2013
- Subjects: Argyrosomus -- Habitat -- South Africa -- Algoa Bay , Argyrosomus -- Behavior -- South Africa -- Algoa Bay , Argyrosomus -- Migration -- South Africa -- Algoa Bay , Estuarine fishes -- South Africa -- Algoa Bay , Habitat selection -- South Africa -- Algoa Bay , Argyrosomus -- South Africa -- Sundays Estuary (Eastern Cape) , Underwater acoustic telemetry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5386 , http://hdl.handle.net/10962/d1020241
- Description: Dusky kob Argyrosomus japonicus is a wide-ranging estuarine-dependent Sciaenid and an important fishery species throughout most of its distribution. It is one of South Africa’s most valuable coastal fishery species. High levels of juvenile exploitation in estuaries and ineffective management regulations have led to stock collapse, highlighting the need to better understand the spatial and temporal aspects of estuarine-dependency and multiple habitat use. Habitat connectivity is a critical property of estuarine-associated fishes and it therefore follows that knowledge of this link is fundamental in understanding population dynamics and the nursery role of estuarine and/or marine habitats. While dusky kob occur in both estuaries and nearshore coastal zones, limited information on connectivity among these habitats exists. The aim of this study is to assess the role of estuarine nursery habitats in the life cycle of the dusky kob by examining multiple habitat connectivity and determining the drivers associated with estuarine use. A total of 96 dusky kob (237–1280 mm total length) were tagged with acoustic transmitters in both the estuarine and marine environments of Algoa Bay, Eastern Cape, South Africa between May 2008 and September 2010. Their movements were monitored using a network of automated data-logging acoustic receivers deployed in the Sundays Estuary, seven neighbouring estuarine habitats, two commercial harbours and various sites within Algoa Bay. And more...
- Full Text:
- Date Issued: 2013
Financial market integration, contagion and volatility transmission: a case of the globally developed markets and developing stock markets in Africa
- Authors: Chima, Anyikwa Izunna
- Date: 2018
- Subjects: Money market , Investment analysis Capital market
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/23935 , vital:30646
- Description: The widespread impact of the 2007 global financial crisis and the subsequent Eurozone sovereign debt crisis added new impetus to the on-going international discussions about the sustainability of a financial integration model. Moreover, the crisis revealed the complexity of the international transmission of financial shocks and the financial vulnerabilities of different financial markets. More so, it exposed the major weaknesses in our knowledge of how the forces that drive global financial systems operate. This is compounded by a failure to appreciate the scope of interdependencies that exist across markets and their potential to destabilise the global financial system in times of crises. At the heart of this weakness is the inability to accurately understand the various propagation mechanisms and channels through which a crisis from one market is transmitted to other markets. It is against this background that this study is undertaken, in order to empirically investigate the role of financial market integration, contagion and volatility transmission, using weekly data between the period 3 January 2003 to 26 December 2014. The study covers 27 stock markets, comprising 13 African stock markets, 10 developed stock markets and four emerging stock markets. The study employed two empirical frameworks: the first framework focused on the short-run and long-run relationships between African stock markets and major global stock markets using the Johansen co-integration test, Granger causality test, GIRF and GFEVD. The second framework focused on testing evidence of contagion and volatility transmission using the DCC-GJRGARCH model and AS model. The results show that the majority of African stock markets moved together in the long-run with the major global stock markets during the pre-crisis and Eurozone crisis periods. While the long-run relationship between African stock markets and the major global markets disappeared during the period of the global financial crisis, the relationship re-emerged during the Eurozone crisis period. From the analysis of Granger causality test, the results show some differences exist in terms of the relative strength of the causal linkages across markets and periods. However, it was shown that strong causal linkages emerged during the global financial and Eurozone crisis periods relative to the pre-crisis period. Also, the leading role of the major developed markets, compared to the emerging markets, is demonstrated throughout the analysis of causality tests. Moreover, the sensitivity of African markets to shocks from the global markets was clearly highlighted by analysis of the GIRF and GFEVD, especially during both crisis periods. Furthermore, the results from the AS model confirm significant evidence of mean and volatility spill-over effects from the major global markets to African markets especially during the periods of both crises. In addition, the level of volatility was found to be more persistent and asymmetric during both crisis periods compared to the pre-crisis period. The results confirm the existence of contagion effects through the analysis of the conditional correlation during both crisis periods. More importantly, the analysis of conditional correlation emphasised evidence of heightened co-movement between African markets and the major global markets during the periods of crisis. Consequently, the decoupling phenomenon is rejected in favour of synchronisation of business cycles between African stock markets and the major global markets. The findings of this study have several important implications for the policymakers and investors in Africa and the world at large. The findings of this study not only provide some information about the level of financial integration but also the effect of growing financial linkages between African markets and the global markets, which is important for designing appropriate regulatory frameworks. Also, the knowledge about the dynamic interrelationship in terms of contagion and volatility transmission between African markets and the major global markets can be utilised by investors, and thereby help them to make better investment decisions. Consequently, the findings of this study point to a need for policymakers in general and in Africa in particular, to monitor closely changes in financial development in other markets in order to reduce the vulnerability of domestic markets to external shocks. To mitigate the impact of the external shocks, greater co-operation and co-ordination, with proper supervision of different markets‟ fiscal and monetary policies, should be encouraged. Such policies need to be carefully aligned with the objective of external sustainability. This can be achieved through strategic partnerships and mergers, foreign institutional investments, cross market listing of shares, corporatisation of exchanges and the introduction of private ownership. Above all, effective regulation is needed to realise the benefits of financial market integration.
- Full Text:
- Date Issued: 2018
- Authors: Chima, Anyikwa Izunna
- Date: 2018
- Subjects: Money market , Investment analysis Capital market
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/23935 , vital:30646
- Description: The widespread impact of the 2007 global financial crisis and the subsequent Eurozone sovereign debt crisis added new impetus to the on-going international discussions about the sustainability of a financial integration model. Moreover, the crisis revealed the complexity of the international transmission of financial shocks and the financial vulnerabilities of different financial markets. More so, it exposed the major weaknesses in our knowledge of how the forces that drive global financial systems operate. This is compounded by a failure to appreciate the scope of interdependencies that exist across markets and their potential to destabilise the global financial system in times of crises. At the heart of this weakness is the inability to accurately understand the various propagation mechanisms and channels through which a crisis from one market is transmitted to other markets. It is against this background that this study is undertaken, in order to empirically investigate the role of financial market integration, contagion and volatility transmission, using weekly data between the period 3 January 2003 to 26 December 2014. The study covers 27 stock markets, comprising 13 African stock markets, 10 developed stock markets and four emerging stock markets. The study employed two empirical frameworks: the first framework focused on the short-run and long-run relationships between African stock markets and major global stock markets using the Johansen co-integration test, Granger causality test, GIRF and GFEVD. The second framework focused on testing evidence of contagion and volatility transmission using the DCC-GJRGARCH model and AS model. The results show that the majority of African stock markets moved together in the long-run with the major global stock markets during the pre-crisis and Eurozone crisis periods. While the long-run relationship between African stock markets and the major global markets disappeared during the period of the global financial crisis, the relationship re-emerged during the Eurozone crisis period. From the analysis of Granger causality test, the results show some differences exist in terms of the relative strength of the causal linkages across markets and periods. However, it was shown that strong causal linkages emerged during the global financial and Eurozone crisis periods relative to the pre-crisis period. Also, the leading role of the major developed markets, compared to the emerging markets, is demonstrated throughout the analysis of causality tests. Moreover, the sensitivity of African markets to shocks from the global markets was clearly highlighted by analysis of the GIRF and GFEVD, especially during both crisis periods. Furthermore, the results from the AS model confirm significant evidence of mean and volatility spill-over effects from the major global markets to African markets especially during the periods of both crises. In addition, the level of volatility was found to be more persistent and asymmetric during both crisis periods compared to the pre-crisis period. The results confirm the existence of contagion effects through the analysis of the conditional correlation during both crisis periods. More importantly, the analysis of conditional correlation emphasised evidence of heightened co-movement between African markets and the major global markets during the periods of crisis. Consequently, the decoupling phenomenon is rejected in favour of synchronisation of business cycles between African stock markets and the major global markets. The findings of this study have several important implications for the policymakers and investors in Africa and the world at large. The findings of this study not only provide some information about the level of financial integration but also the effect of growing financial linkages between African markets and the global markets, which is important for designing appropriate regulatory frameworks. Also, the knowledge about the dynamic interrelationship in terms of contagion and volatility transmission between African markets and the major global markets can be utilised by investors, and thereby help them to make better investment decisions. Consequently, the findings of this study point to a need for policymakers in general and in Africa in particular, to monitor closely changes in financial development in other markets in order to reduce the vulnerability of domestic markets to external shocks. To mitigate the impact of the external shocks, greater co-operation and co-ordination, with proper supervision of different markets‟ fiscal and monetary policies, should be encouraged. Such policies need to be carefully aligned with the objective of external sustainability. This can be achieved through strategic partnerships and mergers, foreign institutional investments, cross market listing of shares, corporatisation of exchanges and the introduction of private ownership. Above all, effective regulation is needed to realise the benefits of financial market integration.
- Full Text:
- Date Issued: 2018
The biophysical dynamics of the Lower Shire River Floodplain fisheries in Malawi
- Authors: Chimatiro, Sloans Kalumba
- Date: 2005
- Subjects: Shire River Valley (Malawi and Mozambique) Fisheries -- Malawi
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5243 , http://hdl.handle.net/10962/d1005086
- Description: Fishes of African floodplains typically comprise populations having short life cycles, relatively few age groups, more generalised feeding behaviour, and which experience spawning success that is strongly influenced by abiotic factors such as hydrological regime of the river, climatic seasonality and habitat characteristics. In addition, African river-floodplain ecosystems do not have appropriate predictive models for estimating yield in these ecosystems. While most predictive models developed to date for floodplain fisheries have taken into account morpho-edaphic factors, they have generally excluded climatic factors as a mega-determinant of the variability of floodplain fisheries. The principle aim of this thesis has been to develop a predictive management model that incorporates data on essential biological aspects of the target species, characteristics of the habitat as well as overall climatic factors, and thus allow for adaptive management of the fisheries in a continuously fluctuating floodplain environment. Lower Shire Floodplain (34 ⁰ 45’ – 35 ⁰ E and 16 ⁰ 00’-17 ⁰ 15’ S) in Malawi, one of the major rivers-floodplains in the Zambezi Basin, was used to test this type of model. The major hypothesis tested in this study was that “the dynamics of the fishery of Lower Shire Floodplain are driven by and adapted to the seasonal, but predictable, hydro-climatic regime of the floodplain”. The specific objectives were: to describe the floodplain’s climate and hydrological pattern; to develop a quantitative characterisation of the major habitats of the Lower Shire Floodplain; to assess the fishery in terms of size, gear utilisation, gear selectivity and yield; to assess the biological parameters of the target species, necessary for the management of the fishery; to analyse how water fluctuation in the floodplain affects the recruitment and life history of the two target species; and to develop of a predictive hydro-climatic model to benefit the management of the fisheries. The climate of the floodplain was characterised by low (765 ± 198 mm) and fairly variable (Cv = 27%) rainfall, which largely occurred between December and January. The area was generally humid (mean RH 68%), with mild to hot (25- 33ºC) and variable monthly mean diurnal (12ºC) temperature. Four quarterly hydro-climatic seasons were identified and comprised: Quarter 1 (Jul-Sep) characterised by hot, dry weather with a low flood regime; Quarter 2 (Oct-Dec) hot, windy, wet weather with low-but-rising flood regime; Quarter 3 (Jan-Mar) hot humid, wet weather with the flood regime at peak; and Quarter 4 (Apr-Jun) humid and cool weather with receding flood regime. The annual hydrograph of the floodplain was represented by four categories of flood regime as: low (Jul-Sept), low-but-rising (Oct-Dec), peak (Jan- Mar), and falling (Apr-Jun). The floodplain experienced a water deficit of 95.1 mm.year⁻¹, and it was hypothesised that ground water recharge maintained water in the floodplain the rest of the year. Three major habitats were identified in the floodplain. The river-floodplain, characterised by deep fast-flowing water, sandy substrate and little emergent vegetation; the permanently connected lagoons, were shallow (≤ 2 m) with sandymud bottom and slow flowing water; and the seasonally connected lagoons had slowflowing stagnant water, with comparatively more emergent and floating vegetation. Physicochemical characteristics of the habitats varied significantly with hydroclimatic seasons (one-way ANOVA, p ≤ 0.05), indicating the influence of flood regime, which joined the habitats in a non-equilibrial spatial distribution. Consequently, during receding and low flood regimes river-floodplain and permanently connected lagoons exhibited similar characteristics while all three habitats had similar characteristics during the rising and peak flood regimes. It was, therefore, concluded that in floodplains, habitats shift horizontally and vertically according to the water level. Gill nets, cast nets, long line, and fish traps accounted for 99% of the total count of gears, and hence considered the major fishing sectors. Two principal species in the floodplain were the catfish Clarias gariepinus and the cichlid Oreochromis mossambicus. Length-at-maximum-selectivity (ø) and length-at-50%-sexual-maturity (Lm₅₀) for each of the two species showed that although they were selected into the four fishing sectors at lengths above maturity, maximum selectivity into the long line occurred at a length before maturity for O. mossambicus. In addition, the width of the gamma selectivity function (σ) indicated that a considerable proportion of juveniles of the two species were also selected. Therefore, it was decided that management for the floodplain be centred on controlling over-fishing and preserving the spawner stock, by banning seine and mosquito nets, and closing river-floodplain and permanently connected lagoons to fishing during the low flood regime. There were significant seasonal variations in CPUE, lowest in the low flood, and highest during the peak flood regime. Sectioned otoliths were used to determine the age and growth of the two principal species in the floodplain. Marginal zone analysis revealed that annulus formation in all the species occurred during the period of low air and water temperatures, high evaporation and receding water levels, hence a high rate of desiccation and negative water budget. For O. mossambicus, maximum age reached was 6 years while in C. gariepinus it was 9 years. The 3-parameter von Bertalanffy growth model adequately described growth as lt = 177.6(1-e⁻·⁴⁴⁽t ⁺ ¹·⁴³⁾) mm TL for O. mossambicus and lt = 502.9(1-e⁻°·³¹⁽t ⁺ ¹·⁹²⁾) mm TL for C. gariepinus. Female O. mossambicus reached 50%-sexual-maturity at 109 mm SL, while males matured at 105 mm, and both male and female C. gariepinus reached Lm₅₀ at 249 mm SL. The breeding seasons of both O. mossambicus and Clarias gariepinus were between September and March, with modal peaks in January and November, respectively. The annual total mortality rates (Z) were 0.62 ± 0.18 yr⁻¹ for O. mossambicus and 0.93 ± 0.47 yr⁻¹ for C. gariepinus. The mean empirical estimates of natural mortality (M) were 0.46 yr⁻¹ for O. mossambicus and 0.50 year⁻¹ for C. gariepinus, and fishing mortality (F) was calculated as 0.16 yr⁻¹ for O. mossambicus and 0.43 yr⁻¹ for C. gariepinus. The overall exploitation level (Z/K) was 1.41 for O. mossambicus and 3.01 for C. gariepinus. Given that the Z/K ratio was >1, it was asserted that both O. mossambicus and C. gariepinus were mortality-dominated and fairly heavily exploited. However, potential for sustainable exploitation existed since both species showed signs of resilience due short longevity and high rate of natural mortality. Given the limitation of simple exponential models of fish mortality and growth under the situation of seasonal fluctuation of water levels, a simple predictive hydroclimatic- fisheries model was developed. The model predicted the life-history and production parameters fairly accurately (0.53 ≤ r² ≥ 0.98, p ≤ 0.05), and showed that environmental and biological events in the floodplain significantly (0.43 ≤ r² ≥ 0.91, p ≤ 0.05) followed the periodic function of time (day-of-the-year), hence, strongly seasonal. In addition, the flood-pulse preceded all the major biological events, with predicted phase lags established at 55.6º for peak flood, 157.2º, 260.1º, 334.6º and 341.4º for condition factor for O. mossambicus, recruitment, spawning period for O. mossambicus and C. gariepinus, respectively. Therefore, it was recommended that water obstruction on the Shire River must ensure sufficient water flow during the peak flood and spawning period to allow flooding and inundation of the floodplain in order to create habitat favourable for spawning and feeding as well as improve recruitment.
- Full Text:
- Date Issued: 2005
- Authors: Chimatiro, Sloans Kalumba
- Date: 2005
- Subjects: Shire River Valley (Malawi and Mozambique) Fisheries -- Malawi
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5243 , http://hdl.handle.net/10962/d1005086
- Description: Fishes of African floodplains typically comprise populations having short life cycles, relatively few age groups, more generalised feeding behaviour, and which experience spawning success that is strongly influenced by abiotic factors such as hydrological regime of the river, climatic seasonality and habitat characteristics. In addition, African river-floodplain ecosystems do not have appropriate predictive models for estimating yield in these ecosystems. While most predictive models developed to date for floodplain fisheries have taken into account morpho-edaphic factors, they have generally excluded climatic factors as a mega-determinant of the variability of floodplain fisheries. The principle aim of this thesis has been to develop a predictive management model that incorporates data on essential biological aspects of the target species, characteristics of the habitat as well as overall climatic factors, and thus allow for adaptive management of the fisheries in a continuously fluctuating floodplain environment. Lower Shire Floodplain (34 ⁰ 45’ – 35 ⁰ E and 16 ⁰ 00’-17 ⁰ 15’ S) in Malawi, one of the major rivers-floodplains in the Zambezi Basin, was used to test this type of model. The major hypothesis tested in this study was that “the dynamics of the fishery of Lower Shire Floodplain are driven by and adapted to the seasonal, but predictable, hydro-climatic regime of the floodplain”. The specific objectives were: to describe the floodplain’s climate and hydrological pattern; to develop a quantitative characterisation of the major habitats of the Lower Shire Floodplain; to assess the fishery in terms of size, gear utilisation, gear selectivity and yield; to assess the biological parameters of the target species, necessary for the management of the fishery; to analyse how water fluctuation in the floodplain affects the recruitment and life history of the two target species; and to develop of a predictive hydro-climatic model to benefit the management of the fisheries. The climate of the floodplain was characterised by low (765 ± 198 mm) and fairly variable (Cv = 27%) rainfall, which largely occurred between December and January. The area was generally humid (mean RH 68%), with mild to hot (25- 33ºC) and variable monthly mean diurnal (12ºC) temperature. Four quarterly hydro-climatic seasons were identified and comprised: Quarter 1 (Jul-Sep) characterised by hot, dry weather with a low flood regime; Quarter 2 (Oct-Dec) hot, windy, wet weather with low-but-rising flood regime; Quarter 3 (Jan-Mar) hot humid, wet weather with the flood regime at peak; and Quarter 4 (Apr-Jun) humid and cool weather with receding flood regime. The annual hydrograph of the floodplain was represented by four categories of flood regime as: low (Jul-Sept), low-but-rising (Oct-Dec), peak (Jan- Mar), and falling (Apr-Jun). The floodplain experienced a water deficit of 95.1 mm.year⁻¹, and it was hypothesised that ground water recharge maintained water in the floodplain the rest of the year. Three major habitats were identified in the floodplain. The river-floodplain, characterised by deep fast-flowing water, sandy substrate and little emergent vegetation; the permanently connected lagoons, were shallow (≤ 2 m) with sandymud bottom and slow flowing water; and the seasonally connected lagoons had slowflowing stagnant water, with comparatively more emergent and floating vegetation. Physicochemical characteristics of the habitats varied significantly with hydroclimatic seasons (one-way ANOVA, p ≤ 0.05), indicating the influence of flood regime, which joined the habitats in a non-equilibrial spatial distribution. Consequently, during receding and low flood regimes river-floodplain and permanently connected lagoons exhibited similar characteristics while all three habitats had similar characteristics during the rising and peak flood regimes. It was, therefore, concluded that in floodplains, habitats shift horizontally and vertically according to the water level. Gill nets, cast nets, long line, and fish traps accounted for 99% of the total count of gears, and hence considered the major fishing sectors. Two principal species in the floodplain were the catfish Clarias gariepinus and the cichlid Oreochromis mossambicus. Length-at-maximum-selectivity (ø) and length-at-50%-sexual-maturity (Lm₅₀) for each of the two species showed that although they were selected into the four fishing sectors at lengths above maturity, maximum selectivity into the long line occurred at a length before maturity for O. mossambicus. In addition, the width of the gamma selectivity function (σ) indicated that a considerable proportion of juveniles of the two species were also selected. Therefore, it was decided that management for the floodplain be centred on controlling over-fishing and preserving the spawner stock, by banning seine and mosquito nets, and closing river-floodplain and permanently connected lagoons to fishing during the low flood regime. There were significant seasonal variations in CPUE, lowest in the low flood, and highest during the peak flood regime. Sectioned otoliths were used to determine the age and growth of the two principal species in the floodplain. Marginal zone analysis revealed that annulus formation in all the species occurred during the period of low air and water temperatures, high evaporation and receding water levels, hence a high rate of desiccation and negative water budget. For O. mossambicus, maximum age reached was 6 years while in C. gariepinus it was 9 years. The 3-parameter von Bertalanffy growth model adequately described growth as lt = 177.6(1-e⁻·⁴⁴⁽t ⁺ ¹·⁴³⁾) mm TL for O. mossambicus and lt = 502.9(1-e⁻°·³¹⁽t ⁺ ¹·⁹²⁾) mm TL for C. gariepinus. Female O. mossambicus reached 50%-sexual-maturity at 109 mm SL, while males matured at 105 mm, and both male and female C. gariepinus reached Lm₅₀ at 249 mm SL. The breeding seasons of both O. mossambicus and Clarias gariepinus were between September and March, with modal peaks in January and November, respectively. The annual total mortality rates (Z) were 0.62 ± 0.18 yr⁻¹ for O. mossambicus and 0.93 ± 0.47 yr⁻¹ for C. gariepinus. The mean empirical estimates of natural mortality (M) were 0.46 yr⁻¹ for O. mossambicus and 0.50 year⁻¹ for C. gariepinus, and fishing mortality (F) was calculated as 0.16 yr⁻¹ for O. mossambicus and 0.43 yr⁻¹ for C. gariepinus. The overall exploitation level (Z/K) was 1.41 for O. mossambicus and 3.01 for C. gariepinus. Given that the Z/K ratio was >1, it was asserted that both O. mossambicus and C. gariepinus were mortality-dominated and fairly heavily exploited. However, potential for sustainable exploitation existed since both species showed signs of resilience due short longevity and high rate of natural mortality. Given the limitation of simple exponential models of fish mortality and growth under the situation of seasonal fluctuation of water levels, a simple predictive hydroclimatic- fisheries model was developed. The model predicted the life-history and production parameters fairly accurately (0.53 ≤ r² ≥ 0.98, p ≤ 0.05), and showed that environmental and biological events in the floodplain significantly (0.43 ≤ r² ≥ 0.91, p ≤ 0.05) followed the periodic function of time (day-of-the-year), hence, strongly seasonal. In addition, the flood-pulse preceded all the major biological events, with predicted phase lags established at 55.6º for peak flood, 157.2º, 260.1º, 334.6º and 341.4º for condition factor for O. mossambicus, recruitment, spawning period for O. mossambicus and C. gariepinus, respectively. Therefore, it was recommended that water obstruction on the Shire River must ensure sufficient water flow during the peak flood and spawning period to allow flooding and inundation of the floodplain in order to create habitat favourable for spawning and feeding as well as improve recruitment.
- Full Text:
- Date Issued: 2005