Constructing confidence intervals for polarization mode dispersion
- Authors: Erlank, Warrick
- Date: 2008
- Subjects: Fiber optics , Polarization (Light)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10571 , http://hdl.handle.net/10948/951 , Fiber optics , Polarization (Light)
- Description: Polarization mode dispersion (PMD) causes significant impairment in high bit-rate optical telecommunications systems. Knowledge of a fibre’s PMD mean value, and the relevant confidence interval, is essential for determining a fibre’s maximum allowable bit-rate. Various methods of confidence interval construction for time series data were tested in this dissertation using simulation. These included the autocovariance-matrix methods as suggested by Box and Jenkins, as well as the more practical and simpler batch means methods. Some of these methods were shown to be significantly better than the standard method of calculating confidence intervals for non time series data. The best of the tested methods were used on actual PMD data. The effect of using polarization scramblers was also tested.
- Full Text:
- Date Issued: 2008
- Authors: Erlank, Warrick
- Date: 2008
- Subjects: Fiber optics , Polarization (Light)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10571 , http://hdl.handle.net/10948/951 , Fiber optics , Polarization (Light)
- Description: Polarization mode dispersion (PMD) causes significant impairment in high bit-rate optical telecommunications systems. Knowledge of a fibre’s PMD mean value, and the relevant confidence interval, is essential for determining a fibre’s maximum allowable bit-rate. Various methods of confidence interval construction for time series data were tested in this dissertation using simulation. These included the autocovariance-matrix methods as suggested by Box and Jenkins, as well as the more practical and simpler batch means methods. Some of these methods were shown to be significantly better than the standard method of calculating confidence intervals for non time series data. The best of the tested methods were used on actual PMD data. The effect of using polarization scramblers was also tested.
- Full Text:
- Date Issued: 2008
Constructions of masculinity in young men's narratives of violence in the homeplace
- Authors: Stride, Lorenzo
- Date: 2008
- Subjects: Family violence , Masculinity , Men -- Identity , Men -- Psychology
- Language: English
- Type: Thesis , Masters , M Soc Sc (C Psy)
- Identifier: vital:11847 , http://hdl.handle.net/10353/185 , Family violence , Masculinity , Men -- Identity , Men -- Psychology
- Description: This research was undertaken with a view to advancing scholarship on the production and reproduction of notions of masculinity through everyday experiences of violence in the domestic sphere. In particular, the researcher sought to explicate constructions of masculinity in men’s narratives of their experiences of violence in the homeplace. The participants in this study constituted a fairly homogenous sample in terms of age, education, geographic location, and socio-economic status. A homogenous sample was purposefully selected because it aided an analysis of the phenomenon under study without diversions from extraneous variables. Data was collected from semi-structured, personal, in-depth, face-to-face interviews with eight young men. In these interviews participants were asked to recall and to talk about one particular experience of domestic violence that they witnessed or that had happened to them in the past. Photo elicitation was used as a reflective technique aimed at facilitating recall and discussion during the interviews. Data was analysed by means of a discourse analysis. The main findings of this research were that the participants grew up in communities where a more traditional hegemonic masculinity was commonplace and where violence as a means of exerting control was associated with being a ‘real man’. The participants did however question this notion of masculinity as a result of their experiences, particularly when they perceived the violence that they had been exposed to as excessive or unwarranted.
- Full Text:
- Date Issued: 2008
- Authors: Stride, Lorenzo
- Date: 2008
- Subjects: Family violence , Masculinity , Men -- Identity , Men -- Psychology
- Language: English
- Type: Thesis , Masters , M Soc Sc (C Psy)
- Identifier: vital:11847 , http://hdl.handle.net/10353/185 , Family violence , Masculinity , Men -- Identity , Men -- Psychology
- Description: This research was undertaken with a view to advancing scholarship on the production and reproduction of notions of masculinity through everyday experiences of violence in the domestic sphere. In particular, the researcher sought to explicate constructions of masculinity in men’s narratives of their experiences of violence in the homeplace. The participants in this study constituted a fairly homogenous sample in terms of age, education, geographic location, and socio-economic status. A homogenous sample was purposefully selected because it aided an analysis of the phenomenon under study without diversions from extraneous variables. Data was collected from semi-structured, personal, in-depth, face-to-face interviews with eight young men. In these interviews participants were asked to recall and to talk about one particular experience of domestic violence that they witnessed or that had happened to them in the past. Photo elicitation was used as a reflective technique aimed at facilitating recall and discussion during the interviews. Data was analysed by means of a discourse analysis. The main findings of this research were that the participants grew up in communities where a more traditional hegemonic masculinity was commonplace and where violence as a means of exerting control was associated with being a ‘real man’. The participants did however question this notion of masculinity as a result of their experiences, particularly when they perceived the violence that they had been exposed to as excessive or unwarranted.
- Full Text:
- Date Issued: 2008
Contextual obstacles to the delivery of effective psychological treatment of PTSD in a South African community setting
- Authors: Swartz, Kerry
- Date: 2008
- Subjects: Post-traumatic stress disorder -- Treatment -- South Africa Rape victims -- Counseling of -- South Africa Psychic trauma -- Treatment HIV infections -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3068 , http://hdl.handle.net/10962/d1002577
- Description: The present study presents three individual cases; all three clients had endured a traumatic event, namely rape, and all three met the criteria for PTSD. Despite the fact that each of the clients was initially assessed as being a suitable candidate for psychological treatment, none of the cases proceeded to the therapy phase of treatment. A number of obstacles, both personal and contextual, were encountered during treatment implementation, preventing or limiting a successful outcome of psychological treatment in each case. An examination of these cases highlights a few of the many obstacles frequently faced when delivering psychological treatment to the South African context. In so doing, this research provides an opportunity to consider the possible reasons for the limited documentation of treatment efficacy within the South African context, as well as to enhance our understanding of and sensitivity towards the cultural and contextual factors playing a role in psychological treatment.
- Full Text:
- Date Issued: 2008
- Authors: Swartz, Kerry
- Date: 2008
- Subjects: Post-traumatic stress disorder -- Treatment -- South Africa Rape victims -- Counseling of -- South Africa Psychic trauma -- Treatment HIV infections -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3068 , http://hdl.handle.net/10962/d1002577
- Description: The present study presents three individual cases; all three clients had endured a traumatic event, namely rape, and all three met the criteria for PTSD. Despite the fact that each of the clients was initially assessed as being a suitable candidate for psychological treatment, none of the cases proceeded to the therapy phase of treatment. A number of obstacles, both personal and contextual, were encountered during treatment implementation, preventing or limiting a successful outcome of psychological treatment in each case. An examination of these cases highlights a few of the many obstacles frequently faced when delivering psychological treatment to the South African context. In so doing, this research provides an opportunity to consider the possible reasons for the limited documentation of treatment efficacy within the South African context, as well as to enhance our understanding of and sensitivity towards the cultural and contextual factors playing a role in psychological treatment.
- Full Text:
- Date Issued: 2008
Corporate governance for sustainable development : implications for non-executive directors and the management accounting function
- Jodwana, Thembinkosi Anthony Vincent
- Authors: Jodwana, Thembinkosi Anthony Vincent
- Date: 2008
- Subjects: Corporate governance , Sustainable development , Directors of corporations , Corporations -- Finance -- Management
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:8975 , http://hdl.handle.net/10948/807 , Corporate governance , Sustainable development , Directors of corporations , Corporations -- Finance -- Management
- Description: This paper will discuss the role that corporate governance can play in promoting sustainable development. Sustainable development is discussed in relation to three things: • Current development which does not result in the damage and destruction of the environment to the detriment of future inhabitants of this planet. This paper will discuss the role that corporate governance can play in promoting sustainable development. Sustainable development is discussed in relation to three things: • Current development which does not result in the damage and destruction of the environment to the detriment of future inhabitants of this planet.
- Full Text:
- Date Issued: 2008
- Authors: Jodwana, Thembinkosi Anthony Vincent
- Date: 2008
- Subjects: Corporate governance , Sustainable development , Directors of corporations , Corporations -- Finance -- Management
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:8975 , http://hdl.handle.net/10948/807 , Corporate governance , Sustainable development , Directors of corporations , Corporations -- Finance -- Management
- Description: This paper will discuss the role that corporate governance can play in promoting sustainable development. Sustainable development is discussed in relation to three things: • Current development which does not result in the damage and destruction of the environment to the detriment of future inhabitants of this planet. This paper will discuss the role that corporate governance can play in promoting sustainable development. Sustainable development is discussed in relation to three things: • Current development which does not result in the damage and destruction of the environment to the detriment of future inhabitants of this planet.
- Full Text:
- Date Issued: 2008
Corporeal identification in selected works by Berni Searle
- Authors: Taggart, Emma
- Date: 2008
- Subjects: Searle, Berni Lacan, Jacques, 1901-1981 -- Criticism and interpretation Merleau-Ponty, Maurice, 1908-1961 -- Criticism and interpretation Women artists -- South Africa Body art -- South Africa Self-portraits
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2434 , http://hdl.handle.net/10962/d1004576
- Description: Through a detailed analysis of a selection of works produced between 1999 and 2003 by the South African artist Berni Searle, this thesis explores the need to theorise a corporeal viewer in the process of interpreting art works. Such an approach is particularly necessary when dealing with an artist such as Searle because her work, which deals predominantly with the theme of identity, appeals not only to conceptual but also to experiential and corporeal understandings of identity. Searle incorporates the viewer into an experience of her own identity through a physical identification that the viewer feels in relation to her work. For viewers this means that they are made aware of how their own identity in the moment of interpretation is contingent on visual, mental and physical components. In order to develop this argument the work of psychoanalyst Jacques Lacan and the phenomenologist Maurice Merleau-Ponty is drawn on. These two theorists are very useful for an argument of this nature because both interpret identity as a construction involving an enfolding between the mind and, via the act of vision, the body of the subject. Through an inclusion of the corporeal element in interpretation, this thesis also offers a critique of interpretive theories that would reduce analysis to an interaction between eye and mind by analyzing how the viewer's body participates in the act of looking.
- Full Text:
- Date Issued: 2008
- Authors: Taggart, Emma
- Date: 2008
- Subjects: Searle, Berni Lacan, Jacques, 1901-1981 -- Criticism and interpretation Merleau-Ponty, Maurice, 1908-1961 -- Criticism and interpretation Women artists -- South Africa Body art -- South Africa Self-portraits
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2434 , http://hdl.handle.net/10962/d1004576
- Description: Through a detailed analysis of a selection of works produced between 1999 and 2003 by the South African artist Berni Searle, this thesis explores the need to theorise a corporeal viewer in the process of interpreting art works. Such an approach is particularly necessary when dealing with an artist such as Searle because her work, which deals predominantly with the theme of identity, appeals not only to conceptual but also to experiential and corporeal understandings of identity. Searle incorporates the viewer into an experience of her own identity through a physical identification that the viewer feels in relation to her work. For viewers this means that they are made aware of how their own identity in the moment of interpretation is contingent on visual, mental and physical components. In order to develop this argument the work of psychoanalyst Jacques Lacan and the phenomenologist Maurice Merleau-Ponty is drawn on. These two theorists are very useful for an argument of this nature because both interpret identity as a construction involving an enfolding between the mind and, via the act of vision, the body of the subject. Through an inclusion of the corporeal element in interpretation, this thesis also offers a critique of interpretive theories that would reduce analysis to an interaction between eye and mind by analyzing how the viewer's body participates in the act of looking.
- Full Text:
- Date Issued: 2008
Corporeal tales : an investigation into narrative form in contemporary South African dance and choreography
- Authors: Parker, Alan Charles
- Date: 2008
- Subjects: Sichel, Adrienne Krouse, Matthew Dance -- South Africa Choreography -- South Africa Choreographers -- South Africa Dance criticism -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2157 , http://hdl.handle.net/10962/d1007658
- Description: In the years following the fall of Apartheid in South Africa, dance and choreography have undergone considerable transformation. This investigation stems from one observation relative to this change that has been articulated by two of South Africa's most respected dance critics, Adrienne Sichel and Matthew Krouse. Both critics have noted a growing concern for narrative in South African contemporary choreography, coupled with an apparent propensity for narratives of a distinctly personal and 'autobiographical' nature. In Part One: 'Just after the beginning', the proposed preoccupation with narrative in South African contemporary choreography is discussed in light of the relationship between narrative and the notion of personal identity. The use of the performed narrative as a medium to explore questions about identity is offered as one explanation underpinning this increased proclivity, where the interrogation of the form of the danced narrative provides a site for exploration of personal identity. Part Two: 'Somewhere in the middle' interrogates the notion of form through an in-depth discussion of the experimentation with form within theatrical and antitheatrical dance traditions over the last fifty years. Specific works by three selected South African choreographers (Ginslov, Maqoma and Sabbagha) are discussed in terms of their general approach to narrative form. This provides an illustration of some of the approaches to narrative form emergent in contemporary South African choreographic practices. Part Three: 'Nearing the end' offers Acty Tang's Chaste (2007) as a case study to illustrate the practical application of the dance narrative as a means to interrogate questions relating to personal identity. A detailed analysis of Tang's particular approach to forming the narrative of Chaste is conducted, exposing the intertextual, multimedia and multidisciplinary approach to creating the danced narrative.
- Full Text:
- Date Issued: 2008
- Authors: Parker, Alan Charles
- Date: 2008
- Subjects: Sichel, Adrienne Krouse, Matthew Dance -- South Africa Choreography -- South Africa Choreographers -- South Africa Dance criticism -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2157 , http://hdl.handle.net/10962/d1007658
- Description: In the years following the fall of Apartheid in South Africa, dance and choreography have undergone considerable transformation. This investigation stems from one observation relative to this change that has been articulated by two of South Africa's most respected dance critics, Adrienne Sichel and Matthew Krouse. Both critics have noted a growing concern for narrative in South African contemporary choreography, coupled with an apparent propensity for narratives of a distinctly personal and 'autobiographical' nature. In Part One: 'Just after the beginning', the proposed preoccupation with narrative in South African contemporary choreography is discussed in light of the relationship between narrative and the notion of personal identity. The use of the performed narrative as a medium to explore questions about identity is offered as one explanation underpinning this increased proclivity, where the interrogation of the form of the danced narrative provides a site for exploration of personal identity. Part Two: 'Somewhere in the middle' interrogates the notion of form through an in-depth discussion of the experimentation with form within theatrical and antitheatrical dance traditions over the last fifty years. Specific works by three selected South African choreographers (Ginslov, Maqoma and Sabbagha) are discussed in terms of their general approach to narrative form. This provides an illustration of some of the approaches to narrative form emergent in contemporary South African choreographic practices. Part Three: 'Nearing the end' offers Acty Tang's Chaste (2007) as a case study to illustrate the practical application of the dance narrative as a means to interrogate questions relating to personal identity. A detailed analysis of Tang's particular approach to forming the narrative of Chaste is conducted, exposing the intertextual, multimedia and multidisciplinary approach to creating the danced narrative.
- Full Text:
- Date Issued: 2008
Cranial ontogeny of the sole, dagetichthys marginatus (soleidae), with considerations on the feeding ability of larvae and early juveniles
- Ende, Stephan Siegfried Werner
- Authors: Ende, Stephan Siegfried Werner
- Date: 2008
- Subjects: Soleidae , Fishes -- Larvae -- Food , Flatfishes -- Nutrition , Artemia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5250 , http://hdl.handle.net/10962/d1005093 , Soleidae , Fishes -- Larvae -- Food , Flatfishes -- Nutrition , Artemia
- Description: The overall aim of this study was to gain a better understanding of the feeding mechanisms of the larvae and early juveniles of the sole, Dagetichthys marginatus (Soleidae), with which to assess the suitability of current feeding protocols and to facilitate the development of an appropriate pelleted feed. This was achieved by examining the ontogeny of the cranium of laboratory reared sole, with particular emphasis on those elements associated with feeding and by comparing the cranium of juvenile fish with that of adult fish. At 4 dah (days after hatch) Dagetichthys marginatus larvae develop the first rudimentary branchial arches that facilitates the capture and ingestion of food items. Subsequent development of cranial structures, such as the oral jaws, suspensorium, neurocranium, hyoid and branchial arches and the opercular apparatus enables the larvae, at 16 dah, to switch from ram feeding to suction feeding on live prey. The use of live Artemia nauplii from 4 to 16 dah is therefore appropriate. The first morphological asymmetries developed at 16 dah in the dentaries and at 22 dah the maxillae and the premaxillae began to show asymmetries. Teeth were present only on the blind side of the oral jaw elements and during this period (16 to 22 dah) the existing elements began to ossify. From 16 to 35 dah the standard feeding protocol consists of a combination of pelagic (Artemia metanauplii) and benthic prey (dead, frozen Artemia nauplii) and from 25 dah onwards a sinking pellet is provided. The time (dah) at which frozen Artemia and sinking pellets were provided, appropriately corresponded to the initiation of benthic feeding behaviour. However at this stage the use of pelagic Artemia metanauplii is inappropriate and unnecessary. At 31 dah the cranial morphology resembled that of adult fish. Adult D. marginatus display extreme asymmetries among the elements of the oral jaws, the suspensorium and certain elements of the neurocranium. Elements on the blind side are larger and more robust than those on the ocular side and are adapted for feeding, while those on the ocular side appear to have a respiratory function. From 31 dah the cranial elements are identical to those of adult fish, suggesting that no further feeding behavioural changes occurred and that a sinking pellet, of which the nutrient composition meets the requirements of the fish, would be appropriate for ongrowing.
- Full Text:
- Date Issued: 2008
- Authors: Ende, Stephan Siegfried Werner
- Date: 2008
- Subjects: Soleidae , Fishes -- Larvae -- Food , Flatfishes -- Nutrition , Artemia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5250 , http://hdl.handle.net/10962/d1005093 , Soleidae , Fishes -- Larvae -- Food , Flatfishes -- Nutrition , Artemia
- Description: The overall aim of this study was to gain a better understanding of the feeding mechanisms of the larvae and early juveniles of the sole, Dagetichthys marginatus (Soleidae), with which to assess the suitability of current feeding protocols and to facilitate the development of an appropriate pelleted feed. This was achieved by examining the ontogeny of the cranium of laboratory reared sole, with particular emphasis on those elements associated with feeding and by comparing the cranium of juvenile fish with that of adult fish. At 4 dah (days after hatch) Dagetichthys marginatus larvae develop the first rudimentary branchial arches that facilitates the capture and ingestion of food items. Subsequent development of cranial structures, such as the oral jaws, suspensorium, neurocranium, hyoid and branchial arches and the opercular apparatus enables the larvae, at 16 dah, to switch from ram feeding to suction feeding on live prey. The use of live Artemia nauplii from 4 to 16 dah is therefore appropriate. The first morphological asymmetries developed at 16 dah in the dentaries and at 22 dah the maxillae and the premaxillae began to show asymmetries. Teeth were present only on the blind side of the oral jaw elements and during this period (16 to 22 dah) the existing elements began to ossify. From 16 to 35 dah the standard feeding protocol consists of a combination of pelagic (Artemia metanauplii) and benthic prey (dead, frozen Artemia nauplii) and from 25 dah onwards a sinking pellet is provided. The time (dah) at which frozen Artemia and sinking pellets were provided, appropriately corresponded to the initiation of benthic feeding behaviour. However at this stage the use of pelagic Artemia metanauplii is inappropriate and unnecessary. At 31 dah the cranial morphology resembled that of adult fish. Adult D. marginatus display extreme asymmetries among the elements of the oral jaws, the suspensorium and certain elements of the neurocranium. Elements on the blind side are larger and more robust than those on the ocular side and are adapted for feeding, while those on the ocular side appear to have a respiratory function. From 31 dah the cranial elements are identical to those of adult fish, suggesting that no further feeding behavioural changes occurred and that a sinking pellet, of which the nutrient composition meets the requirements of the fish, would be appropriate for ongrowing.
- Full Text:
- Date Issued: 2008
Critiquing the viability of a trade biased approach to regional integration in Southern Africa
- Authors: Chipendo, Kudakwashe
- Date: 2008
- Subjects: Regionalism -- Africa, Southern , International economic integration
- Language: English
- Type: Thesis , Masters , M Soc Sc (Dev)
- Identifier: vital:11409 , http://hdl.handle.net/10353/163 , Regionalism -- Africa, Southern , International economic integration
- Description: Africa’s international marginalization is preponderantly conceptualized through world systems approaches, particularly structural dependency. Consequently, the region’s socioeconomic quagmire, characterized by economic stagnation, abysmal poverty, inequality and foreign dependency, is often attributed to its colonial heritage. Particular reference is made to the small size of the African state and its structural specialization in primary production. Collective self reliance based on mutual interdependence (regional integration) thus suggests itself as a logical way to overcome the structural constraints imposed by the small size of the state, while at the same time representing a viable alternative to asymmetric trade with developed countries. It is within the context of this theoretical framework that this study critiques the predisposition of the regional body in Southern Africa, the Southern African Development Community (SADC), towards a trade biased approach to regional integration (market integration). This critique is based on theoretical and empirical findings showing that trade led strategies are primarily suited for developed countries with robust manufacturing industries and complimentary production structures. Countries in Southern Africa are however characterized by a near absence of manufacturing industries, are at different levels of development and show low levels of trade complementarities. This study therefore concludes that market integration is an inappropriate strategy for regional integration in Southern Africa and in the process suggests development integration – a political economy approach, as an alternative.
- Full Text:
- Date Issued: 2008
- Authors: Chipendo, Kudakwashe
- Date: 2008
- Subjects: Regionalism -- Africa, Southern , International economic integration
- Language: English
- Type: Thesis , Masters , M Soc Sc (Dev)
- Identifier: vital:11409 , http://hdl.handle.net/10353/163 , Regionalism -- Africa, Southern , International economic integration
- Description: Africa’s international marginalization is preponderantly conceptualized through world systems approaches, particularly structural dependency. Consequently, the region’s socioeconomic quagmire, characterized by economic stagnation, abysmal poverty, inequality and foreign dependency, is often attributed to its colonial heritage. Particular reference is made to the small size of the African state and its structural specialization in primary production. Collective self reliance based on mutual interdependence (regional integration) thus suggests itself as a logical way to overcome the structural constraints imposed by the small size of the state, while at the same time representing a viable alternative to asymmetric trade with developed countries. It is within the context of this theoretical framework that this study critiques the predisposition of the regional body in Southern Africa, the Southern African Development Community (SADC), towards a trade biased approach to regional integration (market integration). This critique is based on theoretical and empirical findings showing that trade led strategies are primarily suited for developed countries with robust manufacturing industries and complimentary production structures. Countries in Southern Africa are however characterized by a near absence of manufacturing industries, are at different levels of development and show low levels of trade complementarities. This study therefore concludes that market integration is an inappropriate strategy for regional integration in Southern Africa and in the process suggests development integration – a political economy approach, as an alternative.
- Full Text:
- Date Issued: 2008
Cross-cultural normative indicators on the Wechsler Memory Scale (WMS) associate learning and visual reproduction subtests
- Authors: Fike, Lauren
- Date: 2008
- Subjects: Wechsler Memory Scale -- Cross-cultural studies Memory -- Testing Memory -- Cross-cultural studies Memory Assessment Scales Short-term memory -- Testing Long-term memory -- Testing
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2975 , http://hdl.handle.net/10962/d1002484
- Description: A comprehensive battery of commonly used neuropsychological tests, including the WMS Associate Learning and Visual Reproduction subtests, forming the focus of this study, were administered to a southern African sample (n = 33, age range 18-40). This sample composed of black South African, IsiXhosa speakers with an educational level of Grade 11 and 12, derived through DET and former DET schooling. The gender demographics were as follows; females n = 21 and males n = 12. This sample was purposefully selected based on current cross-cultural research which suggests that individuals matching these above-mentioned demographics are significantly disadvantaged when compared to available neuropsychological norms. This is due to the fact that current norms have been created in contexts with socio-cultural influences; including culture, language and quantity and quality of education distinctly dissimilar to individuals like that composed in the sample. Hence the purpose of this study was fourfold namely; 1) Describe and consider socio-cultural factors and the influence on test performance 2) Provide descriptive and preliminary normative data on this neuropsychologically underrepresented population 3) Compare test performance between age and gender through stratification of the sample and finally to 4) Evaluate the current norms of the two WMS subtests and assess their validity for black South Africans with DET and former DET schooling with comparisons to the results found in the study. Information derived from the statistical analyses indicated that a higher performance in favour of the younger group over the older age range was consistently found for both WMS subtests. With regards to gender, some higher means were evident for the male population in the sample than was produced by the female group. Lastly, due to the fact that most scores derived from the sample were considerably lower when compared to the available norms, it is felt that socio-cultural factors prevalent to this population are a significant cause of lower test performance and thus warrant the development of appropriate normative indicators.
- Full Text:
- Date Issued: 2008
- Authors: Fike, Lauren
- Date: 2008
- Subjects: Wechsler Memory Scale -- Cross-cultural studies Memory -- Testing Memory -- Cross-cultural studies Memory Assessment Scales Short-term memory -- Testing Long-term memory -- Testing
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2975 , http://hdl.handle.net/10962/d1002484
- Description: A comprehensive battery of commonly used neuropsychological tests, including the WMS Associate Learning and Visual Reproduction subtests, forming the focus of this study, were administered to a southern African sample (n = 33, age range 18-40). This sample composed of black South African, IsiXhosa speakers with an educational level of Grade 11 and 12, derived through DET and former DET schooling. The gender demographics were as follows; females n = 21 and males n = 12. This sample was purposefully selected based on current cross-cultural research which suggests that individuals matching these above-mentioned demographics are significantly disadvantaged when compared to available neuropsychological norms. This is due to the fact that current norms have been created in contexts with socio-cultural influences; including culture, language and quantity and quality of education distinctly dissimilar to individuals like that composed in the sample. Hence the purpose of this study was fourfold namely; 1) Describe and consider socio-cultural factors and the influence on test performance 2) Provide descriptive and preliminary normative data on this neuropsychologically underrepresented population 3) Compare test performance between age and gender through stratification of the sample and finally to 4) Evaluate the current norms of the two WMS subtests and assess their validity for black South Africans with DET and former DET schooling with comparisons to the results found in the study. Information derived from the statistical analyses indicated that a higher performance in favour of the younger group over the older age range was consistently found for both WMS subtests. With regards to gender, some higher means were evident for the male population in the sample than was produced by the female group. Lastly, due to the fact that most scores derived from the sample were considerably lower when compared to the available norms, it is felt that socio-cultural factors prevalent to this population are a significant cause of lower test performance and thus warrant the development of appropriate normative indicators.
- Full Text:
- Date Issued: 2008
Curriculum recontextualising using gardens for the health promotion in the life orientation learning area of the senior phase
- Authors: Jenkins, Msawenkosi Wiseman
- Date: 2008
- Subjects: Environmental education -- South Africa -- Eastern Cape -- Case studies School gardens -- South Africa -- Eastern Cape Gardening -- Study and teaching (Secondary) -- South Africa -- Eastern Cape Environmental education -- Curricula -- South Africa -- Eastern Cape Environmental education -- Curricula -- Case studies Environmental policy -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1487 , http://hdl.handle.net/10962/d1003368
- Description: With a view to understanding how curriculum is interpreted at classroom practice level, the study examined three stories of how the environmental discourse of the National Curriculum Statements (R-9) was recontextualised using school gardens in the Life Orientation Learning Area for the Senior Phase. To understand how the curriculum is recontextualised, I used Bernstein's theory of recontexutalisation where he explained how official pedagogic discourse (OPD) (in this case the environmental discourse is first delocated once it is transferred from the field of production (FOP) and relocated in the recontextualising field (where teacher educators and departmental officials mediate the discourse) and in the field of reproduction (FOR) which is the classroom and school. Bernstein explained that as the discourse is delocated and relocated it undergoes transformation. This transformation is influenced by practitioners' prior-knowledge, experience, culture and beliefs and other factors. To understand how transformation of the environmental discourse takes place, Bernstein's conceptual constructs of selective appropriation and ideological transformation were applied to an interpretation of three lesson processes, to explain how the discourse was changed. Each lesson was reviewed in terms of the selective appropriations and ideological transformations which took place. All three of the lessons observed took place in one school, and as such the study is designed as an interpretive case study where I have tried to make meaning from a rich, thick description of a specific case context. The school is located in Bizana, one of the villages in the O.R. Tambo District Municipality in the Eastern Cape Province,, and is currently in the process of implementing South Africa’s new National Curriculum Statement (NCS) like all other schools in South Africa. In conducting the research I observed lessons, interviewed the learners and teachers, and a community member and the manager of the SANBI greening project, and I also analysed documents which included the NCS for Life Orientation, and teachers planning documents and learners work produced in the lessons. I started the study by conducting a document analysis of the NCS, through which I identified dimensions of the Official Pedagogic Discourse. This was used as a framework to review the lessons to understand how the OPD was being recontextualised. The study concludes by discussing the key findings of the study in the form of a set of analytical statements. Some of the findings indicate that teachers have not been given adequate training for understanding and implementing the NCS which affects the recontextualisation process. The study shows that there is a dire need for professional development if the OPD is to be interpreted adequately by teachers so that its implementation at the meso and micro- levels becomes clear and effective.
- Full Text:
- Date Issued: 2008
- Authors: Jenkins, Msawenkosi Wiseman
- Date: 2008
- Subjects: Environmental education -- South Africa -- Eastern Cape -- Case studies School gardens -- South Africa -- Eastern Cape Gardening -- Study and teaching (Secondary) -- South Africa -- Eastern Cape Environmental education -- Curricula -- South Africa -- Eastern Cape Environmental education -- Curricula -- Case studies Environmental policy -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1487 , http://hdl.handle.net/10962/d1003368
- Description: With a view to understanding how curriculum is interpreted at classroom practice level, the study examined three stories of how the environmental discourse of the National Curriculum Statements (R-9) was recontextualised using school gardens in the Life Orientation Learning Area for the Senior Phase. To understand how the curriculum is recontextualised, I used Bernstein's theory of recontexutalisation where he explained how official pedagogic discourse (OPD) (in this case the environmental discourse is first delocated once it is transferred from the field of production (FOP) and relocated in the recontextualising field (where teacher educators and departmental officials mediate the discourse) and in the field of reproduction (FOR) which is the classroom and school. Bernstein explained that as the discourse is delocated and relocated it undergoes transformation. This transformation is influenced by practitioners' prior-knowledge, experience, culture and beliefs and other factors. To understand how transformation of the environmental discourse takes place, Bernstein's conceptual constructs of selective appropriation and ideological transformation were applied to an interpretation of three lesson processes, to explain how the discourse was changed. Each lesson was reviewed in terms of the selective appropriations and ideological transformations which took place. All three of the lessons observed took place in one school, and as such the study is designed as an interpretive case study where I have tried to make meaning from a rich, thick description of a specific case context. The school is located in Bizana, one of the villages in the O.R. Tambo District Municipality in the Eastern Cape Province,, and is currently in the process of implementing South Africa’s new National Curriculum Statement (NCS) like all other schools in South Africa. In conducting the research I observed lessons, interviewed the learners and teachers, and a community member and the manager of the SANBI greening project, and I also analysed documents which included the NCS for Life Orientation, and teachers planning documents and learners work produced in the lessons. I started the study by conducting a document analysis of the NCS, through which I identified dimensions of the Official Pedagogic Discourse. This was used as a framework to review the lessons to understand how the OPD was being recontextualised. The study concludes by discussing the key findings of the study in the form of a set of analytical statements. Some of the findings indicate that teachers have not been given adequate training for understanding and implementing the NCS which affects the recontextualisation process. The study shows that there is a dire need for professional development if the OPD is to be interpreted adequately by teachers so that its implementation at the meso and micro- levels becomes clear and effective.
- Full Text:
- Date Issued: 2008
Customer relations management in SMMEs: an integrated approach
- Authors: Sandekela, Lindela Prince
- Date: 2008
- Subjects: Customer relations -- Management , Small business -- South Africa -- Management , Customer services
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8725 , http://hdl.handle.net/10948/889 , Customer relations -- Management , Small business -- South Africa -- Management , Customer services
- Description: The research study was conducted to cover the Buffalo City Municipality (BCM) retail industry with direct emphasis on the supermarket industry. The research problem is as a result of the retail businesses in the BCM that continue to consider that if they have large data warehouses with masses of customer information, they have all what it takes to run a profitable business. Their failure to understand the organizational implications of moving towards a customer-centric approach often results in high costs from bad customer service and handling of customer complaints. The main problem was stated and sub-problems introduced from the main problem to address them by way of qualitative and quantitative research. Related literature was reviewed on Redefining the Customer, Customer Satisfaction and Customer Relationship Management and a Customer Management Model was proposed. During empirical survey, a questionnaire based on literature reviewed was designed for the survey. A pilot study was conducted to identify and rectify problems and shortcomings relating to the questionnaire. The pilot study indicated that the data likely to be collected will address the main and sub-problems of the research. A total of thirty five questionnaires which contained closed-ended and open-ended questions were distributed to the population sample as selected. Results of the study were critically analysed and interpreted quantitatively and qualitatively by means of tables and discussion for the development of an Integrated Model for managing customers. The analysis of the study which was based on the literature reviewed and the findings from the empirical survey were concluded to present a solution to the problem. In view of the shortcomings identified by the literature review and integration thereof with the results of the empirical study, an Integrated Customer Management Model was developed.
- Full Text:
- Date Issued: 2008
- Authors: Sandekela, Lindela Prince
- Date: 2008
- Subjects: Customer relations -- Management , Small business -- South Africa -- Management , Customer services
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8725 , http://hdl.handle.net/10948/889 , Customer relations -- Management , Small business -- South Africa -- Management , Customer services
- Description: The research study was conducted to cover the Buffalo City Municipality (BCM) retail industry with direct emphasis on the supermarket industry. The research problem is as a result of the retail businesses in the BCM that continue to consider that if they have large data warehouses with masses of customer information, they have all what it takes to run a profitable business. Their failure to understand the organizational implications of moving towards a customer-centric approach often results in high costs from bad customer service and handling of customer complaints. The main problem was stated and sub-problems introduced from the main problem to address them by way of qualitative and quantitative research. Related literature was reviewed on Redefining the Customer, Customer Satisfaction and Customer Relationship Management and a Customer Management Model was proposed. During empirical survey, a questionnaire based on literature reviewed was designed for the survey. A pilot study was conducted to identify and rectify problems and shortcomings relating to the questionnaire. The pilot study indicated that the data likely to be collected will address the main and sub-problems of the research. A total of thirty five questionnaires which contained closed-ended and open-ended questions were distributed to the population sample as selected. Results of the study were critically analysed and interpreted quantitatively and qualitatively by means of tables and discussion for the development of an Integrated Model for managing customers. The analysis of the study which was based on the literature reviewed and the findings from the empirical survey were concluded to present a solution to the problem. In view of the shortcomings identified by the literature review and integration thereof with the results of the empirical study, an Integrated Customer Management Model was developed.
- Full Text:
- Date Issued: 2008
Decentralisation and development: the contradictions of local government in Uganda with specific reference to Masindi and Sembabule districts
- Authors: Galiwango, Wasswa Hassan
- Date: 2008
- Subjects: Decentralization in government -- Uganda , Local government -- Uganda , Uganda -- Politics and government
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8238 , http://hdl.handle.net/10948/780 , Decentralization in government -- Uganda , Local government -- Uganda , Uganda -- Politics and government
- Description: Decentralisation is the process through which Central Government transfers authority and functions to sub-national units of the Government and it traces its origin in Uganda from the “ bush” period (1981 – 1986) when Resistance Committees were established by the NRM/A in the Luwero triangle. The Mamdani Commission Report of 1987 on the Local Government system in Uganda recommended devolution of powers. Subsequently, decentralisation was launched in 1992, constitutionalised by the 1995 Constitution, and operationalised by the Local Governments Act (LGA) in 1997. Among the services devolved were education and health, which this study used as case studies to illustrate whether decentralisation has enhanced development in Uganda during the period 1993 – 2006. The study used both primary and secondary data in analysing the linkage between decentralisation and development in the two selected districts in Uganda, namely Masindi and Sembabule. Primary data was collected through interviews, questionnaires and focus group discussions while secondary data was gathered through a literature survey of relevant textbooks, newspapers, reports, legislation and journals. The findings of the study established that if decentralisation is properly planned and implemented it can make a meaningful contribution to enhancing development. However, since decentralisation is a process and not a once-off project, it evolves from one stage to another and, as it does so, it also unfolds new challenges and contradictions that need to be effectively addressed. These challenges include aspects relating to the legal framework, as well as political, fiscal and administrative decentralisation. The study recommended mitigation measures to enhance the efficiency, effectiveness, accountability, transparency, and subsequently the quality of services delivered (development) under decentralised local governance in Uganda.
- Full Text:
- Date Issued: 2008
- Authors: Galiwango, Wasswa Hassan
- Date: 2008
- Subjects: Decentralization in government -- Uganda , Local government -- Uganda , Uganda -- Politics and government
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8238 , http://hdl.handle.net/10948/780 , Decentralization in government -- Uganda , Local government -- Uganda , Uganda -- Politics and government
- Description: Decentralisation is the process through which Central Government transfers authority and functions to sub-national units of the Government and it traces its origin in Uganda from the “ bush” period (1981 – 1986) when Resistance Committees were established by the NRM/A in the Luwero triangle. The Mamdani Commission Report of 1987 on the Local Government system in Uganda recommended devolution of powers. Subsequently, decentralisation was launched in 1992, constitutionalised by the 1995 Constitution, and operationalised by the Local Governments Act (LGA) in 1997. Among the services devolved were education and health, which this study used as case studies to illustrate whether decentralisation has enhanced development in Uganda during the period 1993 – 2006. The study used both primary and secondary data in analysing the linkage between decentralisation and development in the two selected districts in Uganda, namely Masindi and Sembabule. Primary data was collected through interviews, questionnaires and focus group discussions while secondary data was gathered through a literature survey of relevant textbooks, newspapers, reports, legislation and journals. The findings of the study established that if decentralisation is properly planned and implemented it can make a meaningful contribution to enhancing development. However, since decentralisation is a process and not a once-off project, it evolves from one stage to another and, as it does so, it also unfolds new challenges and contradictions that need to be effectively addressed. These challenges include aspects relating to the legal framework, as well as political, fiscal and administrative decentralisation. The study recommended mitigation measures to enhance the efficiency, effectiveness, accountability, transparency, and subsequently the quality of services delivered (development) under decentralised local governance in Uganda.
- Full Text:
- Date Issued: 2008
Depressogenic cognitive schemas, levels of depression and hopelessness among individuals diagnosed with unipolar mood disorder
- Authors: Du Preez, Shereen
- Date: 2008
- Subjects: Neuropsychiatry , Depression, Mental -- South Africa , Depressed persons -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9899 , http://hdl.handle.net/10948/1074 , Neuropsychiatry , Depression, Mental -- South Africa , Depressed persons -- South Africa
- Description: While mood disorders rank within the top ten disabilities worldwide, there has been limited research done on cognitive schemas and the role they play in the development of mood disorders in South Africa. Cognitive conceptualisations of depression typically emphasize the schema-based automatic processing of information. Beck (1967, 1976 & 1987) suggested that schematically driven automatic thinking is a key element in depressive disorders. Research in the field of depression has identified cognitive schemas as a factor which increases an individual’s diathesis to depression. The primary aim of this research is to explore and describe maladaptive cognitive schemas, hopelessness and levels of depression amongst individuals diagnosed with Unipolar Mood Disorder. A further aim of the research has been to explore the relationship between maladaptive cognitive schemas and hopelessness as a diathesis to depression. In order to achieve the objectives, data was collected from a sample of 50 inpatients diagnosed with Unipolar Mood Disorder. The following measures were used: Young’s Schema Questionnaire, Beck's Depression Inventory – 2nd edition and Beck’s Hopelessness Scale. The research is quantitative in nature and takes the form of an exploratory-descriptive study. Data has been analysed by means of descriptive statistics in order to identify the mean, ranges and standard deviation of the measures used. Cross-tabulations have been used to further explore the relationship between the variables mentioned above. It was found that a statistically significant correlation exists between the BDI, BHS and YSQ. Maladaptive cognitive schemas were found to have a strong positive correlation 4 to depression, whereas hopelessness was found to have a less significant role in Unipolar Mood Disorder. The most significant schemas found in relation to hopelessness, were the Social Isolation, Unrelenting Standards and Pessimism schemas. With regards to depression, the most significant schemas were found to be Mistrust, Practical Incompetence, Vulnerability, Subjugation, Self-Sacrifice, Emotional Inhibition, Unrelenting Standards, Entitlement, Insufficient Self-Control, Admiration, Pessimism and Self-Punitiveness. All the above mentioned variables proved to have a statistically significant relationship. The findings of this research study are for the most part consistent with the literature on depression, hopelessness and cognitive vulnerabilities, and all of the above mentioned concepts have been found to be related.
- Full Text:
- Date Issued: 2008
- Authors: Du Preez, Shereen
- Date: 2008
- Subjects: Neuropsychiatry , Depression, Mental -- South Africa , Depressed persons -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9899 , http://hdl.handle.net/10948/1074 , Neuropsychiatry , Depression, Mental -- South Africa , Depressed persons -- South Africa
- Description: While mood disorders rank within the top ten disabilities worldwide, there has been limited research done on cognitive schemas and the role they play in the development of mood disorders in South Africa. Cognitive conceptualisations of depression typically emphasize the schema-based automatic processing of information. Beck (1967, 1976 & 1987) suggested that schematically driven automatic thinking is a key element in depressive disorders. Research in the field of depression has identified cognitive schemas as a factor which increases an individual’s diathesis to depression. The primary aim of this research is to explore and describe maladaptive cognitive schemas, hopelessness and levels of depression amongst individuals diagnosed with Unipolar Mood Disorder. A further aim of the research has been to explore the relationship between maladaptive cognitive schemas and hopelessness as a diathesis to depression. In order to achieve the objectives, data was collected from a sample of 50 inpatients diagnosed with Unipolar Mood Disorder. The following measures were used: Young’s Schema Questionnaire, Beck's Depression Inventory – 2nd edition and Beck’s Hopelessness Scale. The research is quantitative in nature and takes the form of an exploratory-descriptive study. Data has been analysed by means of descriptive statistics in order to identify the mean, ranges and standard deviation of the measures used. Cross-tabulations have been used to further explore the relationship between the variables mentioned above. It was found that a statistically significant correlation exists between the BDI, BHS and YSQ. Maladaptive cognitive schemas were found to have a strong positive correlation 4 to depression, whereas hopelessness was found to have a less significant role in Unipolar Mood Disorder. The most significant schemas found in relation to hopelessness, were the Social Isolation, Unrelenting Standards and Pessimism schemas. With regards to depression, the most significant schemas were found to be Mistrust, Practical Incompetence, Vulnerability, Subjugation, Self-Sacrifice, Emotional Inhibition, Unrelenting Standards, Entitlement, Insufficient Self-Control, Admiration, Pessimism and Self-Punitiveness. All the above mentioned variables proved to have a statistically significant relationship. The findings of this research study are for the most part consistent with the literature on depression, hopelessness and cognitive vulnerabilities, and all of the above mentioned concepts have been found to be related.
- Full Text:
- Date Issued: 2008
Designing accessible portals in South Africa: a case study
- Authors: Meyer, Shaun
- Date: 2008
- Subjects: Web portals -- South Africa -- Port Elizabeth , Web site development -- South Africa -- Port Elizabeth , Internet programming , Web sites -- Design
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9782 , http://hdl.handle.net/10948/770 , Web portals -- South Africa -- Port Elizabeth , Web site development -- South Africa -- Port Elizabeth , Internet programming , Web sites -- Design
- Description: Web portals are considered “gateways” to the World Wide Web. These portals are becoming very popular entry points to the Web by offering important services such as email, news, weather reports, course notes and general information. In addition, some portal sites allow users the option of customising the site according to their personal interests. However, disabled and elderly people encounter many accessibility and usability barriers while accessing web portals. A preliminary review of a university portal was conducted to identify some of these accessibility problems. This treatise presents an overview of the processes to be followed when conducting an accessibility and usability evaluation. In addition, it mentions some guidelines to be considered when specifically designing portals for use by many different users from varying backgrounds.
- Full Text:
- Date Issued: 2008
- Authors: Meyer, Shaun
- Date: 2008
- Subjects: Web portals -- South Africa -- Port Elizabeth , Web site development -- South Africa -- Port Elizabeth , Internet programming , Web sites -- Design
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9782 , http://hdl.handle.net/10948/770 , Web portals -- South Africa -- Port Elizabeth , Web site development -- South Africa -- Port Elizabeth , Internet programming , Web sites -- Design
- Description: Web portals are considered “gateways” to the World Wide Web. These portals are becoming very popular entry points to the Web by offering important services such as email, news, weather reports, course notes and general information. In addition, some portal sites allow users the option of customising the site according to their personal interests. However, disabled and elderly people encounter many accessibility and usability barriers while accessing web portals. A preliminary review of a university portal was conducted to identify some of these accessibility problems. This treatise presents an overview of the processes to be followed when conducting an accessibility and usability evaluation. In addition, it mentions some guidelines to be considered when specifically designing portals for use by many different users from varying backgrounds.
- Full Text:
- Date Issued: 2008
Designing and implementing a new pulsar timer for the Hartebeesthoek Radio Astronomy Observatory
- Authors: Youthed, Andrew David
- Date: 2008
- Subjects: Astronomical observatories , Radio astronomy , Pulsars , Astronomical instruments , Reduced instruction set computers , Random access memory
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5458 , http://hdl.handle.net/10962/d1005243 , Astronomical observatories , Radio astronomy , Pulsars , Astronomical instruments , Reduced instruction set computers , Random access memory
- Description: This thesis outlines the design and implementation of a single channel, dual polarization pulsar timing instrument for the Hartebeesthoek Radio Astronomy Observatory (HartRAO). The new timer is designed to be an improved, temporary replacement for the existing device which has been in operation for over 20 years. The existing device is no longer reliable and is di±cult to maintain. The new pulsar timer is designed to provide improved functional- ity, higher sampling speed, greater pulse resolution, more °exibility and easier maintenance over the existing device. The new device is also designed to keeping changes to the observation system to a minimum until a full de-dispersion timer can be implemented at theobservatory. The design makes use of an 8-bit Reduced Instruction Set Computer (RISC) micro-processor with external Random Access Memory (RAM). The instrument includes an IEEE-488 subsystem for interfacing the pulsar timer to the observation computer system. The microcontroller software is written in assembler code to ensure optimal loop execution speed and deterministic code execution for the system. The design path is discussed and problems encountered during the design process are highlighted. Final testing of the new instrument indicates an improvement in the sam- pling rate of 13.6 times and a significant reduction in 60Hz interference over the existing instrument.
- Full Text:
- Date Issued: 2008
- Authors: Youthed, Andrew David
- Date: 2008
- Subjects: Astronomical observatories , Radio astronomy , Pulsars , Astronomical instruments , Reduced instruction set computers , Random access memory
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5458 , http://hdl.handle.net/10962/d1005243 , Astronomical observatories , Radio astronomy , Pulsars , Astronomical instruments , Reduced instruction set computers , Random access memory
- Description: This thesis outlines the design and implementation of a single channel, dual polarization pulsar timing instrument for the Hartebeesthoek Radio Astronomy Observatory (HartRAO). The new timer is designed to be an improved, temporary replacement for the existing device which has been in operation for over 20 years. The existing device is no longer reliable and is di±cult to maintain. The new pulsar timer is designed to provide improved functional- ity, higher sampling speed, greater pulse resolution, more °exibility and easier maintenance over the existing device. The new device is also designed to keeping changes to the observation system to a minimum until a full de-dispersion timer can be implemented at theobservatory. The design makes use of an 8-bit Reduced Instruction Set Computer (RISC) micro-processor with external Random Access Memory (RAM). The instrument includes an IEEE-488 subsystem for interfacing the pulsar timer to the observation computer system. The microcontroller software is written in assembler code to ensure optimal loop execution speed and deterministic code execution for the system. The design path is discussed and problems encountered during the design process are highlighted. Final testing of the new instrument indicates an improvement in the sam- pling rate of 13.6 times and a significant reduction in 60Hz interference over the existing instrument.
- Full Text:
- Date Issued: 2008
Determinants of household food security in the semi-arid areas of Zimbabwe: a case study of irrigation and non-irrigation farmers in Lupane and Hwange districts
- Authors: Sikwela, Misery Mpuzu
- Date: 2008
- Subjects: Food -- Safety measures , Irrigation farming -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11163 , http://hdl.handle.net/10353/90 , Food -- Safety measures , Irrigation farming -- Zimbabwe
- Description: Lupane and Hwange districts fall under natural region IV and V and lie in the semi-arid regions of Zimbabwe with low and erratic mean annual rainfall not exceeding 600mm. Seventy percent of Zimbabwe’s population lives in communal areas, whose livelihood is based on agriculture. The communities in these areas mainly practice mixed farming systems. However, crop production is constrained by water availability and suitable production techniques. As a result households in these areas are experiencing worsening levels of household food insecurity. Two irrigation schemes were identified for this study and these are located in these two districts. Tshongokwe irrigation scheme is located in Lupane district and Lukosi irrigation scheme is located in Hwange district and these irrigation schemes are about 25 hectares in size. Lupane and Hwange districts are considered to be one of the most food insecure areas in the country because of the frequent droughts and unreliable rainfall in the region. The major tool of enquiry in this study was the questionnaire which was used to collect data from the households that farm on irrigated land and those that farm on dryland farming. Household and farm characteristics were collected using structured questionnaires with the help of locally recruited and trained enumerators. Agricultural production, household consumption and marketing of agricultural produce were accessed using the questionnaire to establish problems experienced by farmers. The main objective of this study was to investigate the determinants of household food security using a logistic regression model. The model was initially fitted with thirteen variables, selected from factors identified by previous researchers that affect food security in communal areas. Six variables were found to be significant at 1, 5 and 10 percent significance level and all had the expected signs except farm size. These factors include access to irrigation, farm size, cattle ownership, fertilizer application, household size and per capita aggregate production. The results obtained were further analyzed to compute partial effects on continuous variables and change in probabilities on the discrete variables for the significant factors in the logistic regression model. Analysis of partial effects revealed that household size, farm size, cattle ownership and per capita aggregate production lead to a greater probability of household being food secure. Change in probability results showed that having access to irrigation and using fertilizer can increase the probability of household being food secure The findings of this study highlight a positive and significant relationship between access to irrigation, fertilizer application, cattle ownership, per capita aggregate production to household food security. Household size and farm size have a negative and significant relationship on household food security. This study shows the effectiveness of irrigated farming over dryland farming in the semi-arid areas. The results show increased agricultural production, crop diversification and higher incomes from irrigation farming as compared to dry land farming. Irrigation farming has enabled many households to diversify their source of income and generate more income. Irrigation has enabled households with irrigation not only to feed themselves throughout the year but also to invest on non-agricultural goods and services from incomes received from crop sales Based on the results from the logistic regression model, it can be concluded that household size, farm size, per capita aggregate production, cattle ownership, fertilizer application and access to irrigation have a positive effect on household food security and the magnitude of changes in conditional probabilities have an impact on household food security.
- Full Text:
- Date Issued: 2008
- Authors: Sikwela, Misery Mpuzu
- Date: 2008
- Subjects: Food -- Safety measures , Irrigation farming -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11163 , http://hdl.handle.net/10353/90 , Food -- Safety measures , Irrigation farming -- Zimbabwe
- Description: Lupane and Hwange districts fall under natural region IV and V and lie in the semi-arid regions of Zimbabwe with low and erratic mean annual rainfall not exceeding 600mm. Seventy percent of Zimbabwe’s population lives in communal areas, whose livelihood is based on agriculture. The communities in these areas mainly practice mixed farming systems. However, crop production is constrained by water availability and suitable production techniques. As a result households in these areas are experiencing worsening levels of household food insecurity. Two irrigation schemes were identified for this study and these are located in these two districts. Tshongokwe irrigation scheme is located in Lupane district and Lukosi irrigation scheme is located in Hwange district and these irrigation schemes are about 25 hectares in size. Lupane and Hwange districts are considered to be one of the most food insecure areas in the country because of the frequent droughts and unreliable rainfall in the region. The major tool of enquiry in this study was the questionnaire which was used to collect data from the households that farm on irrigated land and those that farm on dryland farming. Household and farm characteristics were collected using structured questionnaires with the help of locally recruited and trained enumerators. Agricultural production, household consumption and marketing of agricultural produce were accessed using the questionnaire to establish problems experienced by farmers. The main objective of this study was to investigate the determinants of household food security using a logistic regression model. The model was initially fitted with thirteen variables, selected from factors identified by previous researchers that affect food security in communal areas. Six variables were found to be significant at 1, 5 and 10 percent significance level and all had the expected signs except farm size. These factors include access to irrigation, farm size, cattle ownership, fertilizer application, household size and per capita aggregate production. The results obtained were further analyzed to compute partial effects on continuous variables and change in probabilities on the discrete variables for the significant factors in the logistic regression model. Analysis of partial effects revealed that household size, farm size, cattle ownership and per capita aggregate production lead to a greater probability of household being food secure. Change in probability results showed that having access to irrigation and using fertilizer can increase the probability of household being food secure The findings of this study highlight a positive and significant relationship between access to irrigation, fertilizer application, cattle ownership, per capita aggregate production to household food security. Household size and farm size have a negative and significant relationship on household food security. This study shows the effectiveness of irrigated farming over dryland farming in the semi-arid areas. The results show increased agricultural production, crop diversification and higher incomes from irrigation farming as compared to dry land farming. Irrigation farming has enabled many households to diversify their source of income and generate more income. Irrigation has enabled households with irrigation not only to feed themselves throughout the year but also to invest on non-agricultural goods and services from incomes received from crop sales Based on the results from the logistic regression model, it can be concluded that household size, farm size, per capita aggregate production, cattle ownership, fertilizer application and access to irrigation have a positive effect on household food security and the magnitude of changes in conditional probabilities have an impact on household food security.
- Full Text:
- Date Issued: 2008
Determination and validation of ethno-veterinary practices used as alternatives in controlling cattle ticks by resource-limited farmers in the Eastern Cape Province, South Africa
- Authors: Moyo, Busani
- Date: 2008
- Subjects: Traditional veterinary medicine -- South Africa -- Eastern Cape Province , Ethnozoology -- South Africa -- Eastern Cape Province , Ticks -- South Africa -- Eastern Cape Province
- Language: English
- Type: Thesis , Masters , MSc Agric (Animal Science)
- Identifier: vital:11806 , http://hdl.handle.net/10353/165 , Traditional veterinary medicine -- South Africa -- Eastern Cape Province , Ethnozoology -- South Africa -- Eastern Cape Province , Ticks -- South Africa -- Eastern Cape Province
- Description: Ticks are the most common external parasites of economic importance in the livestock farming sector of Southern Africa. They are vectors of tick-borne diseases and are commonly controlled using conventional acaricides, which are expensive and not readily available to resource-limited farmers. As a result many resource-limited farmers resort to use of alternative materials to control ticks on their livestock. Tick resistance to acaricide is an increasing problem in Southern Africa and poses a real economic threat to livestock and veterinary pharmaceutical industries. The objective of this study was to document and validate the ethno-veterinary remedies used as alternative methods of controlling cattle ticks by resource-limited farmers. A questionnaire survey was conducted in May 2007, at Qolora by-Sea and Nontshinga in Centane district, to determine tick control methods used by resource limited farmers in the Amathole District Municipality of the Eastern Cape Province, South Africa. Furthermore, in vitro and in vivo experiments were done to validate the acaricidal properties of ethnoveterinary remedies used by resource-limited farmers. Ticks were reported to be a major problem, transmitting diseases like anaplasmosis (89.8%), babesiosis (55.9%) and ehrlichiosis (16.9%), they also cause wounds that predispose cattle to screwworm infestation, tick worry and teat damage. All farmers used acaricides and dipping tanks provided by the government to control ticks, as the main tick control method. However, the majority (94.9%) were of the opinion that the dip wash was not effective in controlling ticks. As a result, farmers complemented the government dipping service with use of own initiatives like spraying with conventional acaricides (22%), household disinfectants such as Jeyes fluid (18.6%), used engine oil (10.2%), chickens feeding on ticks (5.1%), manual iv removal (5.1%), and pouricides (1.7%). In addition, some farmers also use plants (6.8%), mainly the leaf of Aloe ferox and the bark of Ptaeroxylon obliquum. The in vitro repellency models showed Jeyes fluid (76.8 and 100% concentrations) and P. obliquum (40%) had repellent properties that lasted 6 hours and 40 minutes respectively while that of, Tabard (35% diethyltoluamide) positive control, lasted for 4 hours when applied against nymphal stages of Rhipicephalus sanguineus ticks. In the contact bio-assay, undiluted used engine oil, T. minuta oil (50%), Ektoban® (Cymiazol 17.5% and cypermethrin 2.5%) and Jeyes fluid (76.8%) caused higher tick mortality of more than 86%. Other materials (A. ferox, Lantana camara and Tagetes minuta) had no repellence and acaricidal properties. In the in vivo study, Jeyes fluid at a concentration of 76.8% and used engine oil displayed efficacy of 71 and 76.4% respectively which was similar to that of the positive control Ektoban® at 97.8% tick load reduction. Among plant materials L. camara at 40% concentrations had an efficacy of 57% while A. ferox, P. obliquum and T. minuta were not effective at all. The remedies used by resource-limited farmers to control ticks vary in efficacy. Their ability to reduce tick load on cattle appears to be promising and a welcome development as their use could probably reduce tick burdens in cattle with less expenditure. However, further investigations need to be done before they are recommended for use. Despite being effective some of the materials have potential toxic effects in animals and also cause environmental contamination and I recommend used engine oil, Jeyes fluid and L. camara for further testing as they showed some efficacy compared to other remedies.
- Full Text:
- Date Issued: 2008
- Authors: Moyo, Busani
- Date: 2008
- Subjects: Traditional veterinary medicine -- South Africa -- Eastern Cape Province , Ethnozoology -- South Africa -- Eastern Cape Province , Ticks -- South Africa -- Eastern Cape Province
- Language: English
- Type: Thesis , Masters , MSc Agric (Animal Science)
- Identifier: vital:11806 , http://hdl.handle.net/10353/165 , Traditional veterinary medicine -- South Africa -- Eastern Cape Province , Ethnozoology -- South Africa -- Eastern Cape Province , Ticks -- South Africa -- Eastern Cape Province
- Description: Ticks are the most common external parasites of economic importance in the livestock farming sector of Southern Africa. They are vectors of tick-borne diseases and are commonly controlled using conventional acaricides, which are expensive and not readily available to resource-limited farmers. As a result many resource-limited farmers resort to use of alternative materials to control ticks on their livestock. Tick resistance to acaricide is an increasing problem in Southern Africa and poses a real economic threat to livestock and veterinary pharmaceutical industries. The objective of this study was to document and validate the ethno-veterinary remedies used as alternative methods of controlling cattle ticks by resource-limited farmers. A questionnaire survey was conducted in May 2007, at Qolora by-Sea and Nontshinga in Centane district, to determine tick control methods used by resource limited farmers in the Amathole District Municipality of the Eastern Cape Province, South Africa. Furthermore, in vitro and in vivo experiments were done to validate the acaricidal properties of ethnoveterinary remedies used by resource-limited farmers. Ticks were reported to be a major problem, transmitting diseases like anaplasmosis (89.8%), babesiosis (55.9%) and ehrlichiosis (16.9%), they also cause wounds that predispose cattle to screwworm infestation, tick worry and teat damage. All farmers used acaricides and dipping tanks provided by the government to control ticks, as the main tick control method. However, the majority (94.9%) were of the opinion that the dip wash was not effective in controlling ticks. As a result, farmers complemented the government dipping service with use of own initiatives like spraying with conventional acaricides (22%), household disinfectants such as Jeyes fluid (18.6%), used engine oil (10.2%), chickens feeding on ticks (5.1%), manual iv removal (5.1%), and pouricides (1.7%). In addition, some farmers also use plants (6.8%), mainly the leaf of Aloe ferox and the bark of Ptaeroxylon obliquum. The in vitro repellency models showed Jeyes fluid (76.8 and 100% concentrations) and P. obliquum (40%) had repellent properties that lasted 6 hours and 40 minutes respectively while that of, Tabard (35% diethyltoluamide) positive control, lasted for 4 hours when applied against nymphal stages of Rhipicephalus sanguineus ticks. In the contact bio-assay, undiluted used engine oil, T. minuta oil (50%), Ektoban® (Cymiazol 17.5% and cypermethrin 2.5%) and Jeyes fluid (76.8%) caused higher tick mortality of more than 86%. Other materials (A. ferox, Lantana camara and Tagetes minuta) had no repellence and acaricidal properties. In the in vivo study, Jeyes fluid at a concentration of 76.8% and used engine oil displayed efficacy of 71 and 76.4% respectively which was similar to that of the positive control Ektoban® at 97.8% tick load reduction. Among plant materials L. camara at 40% concentrations had an efficacy of 57% while A. ferox, P. obliquum and T. minuta were not effective at all. The remedies used by resource-limited farmers to control ticks vary in efficacy. Their ability to reduce tick load on cattle appears to be promising and a welcome development as their use could probably reduce tick burdens in cattle with less expenditure. However, further investigations need to be done before they are recommended for use. Despite being effective some of the materials have potential toxic effects in animals and also cause environmental contamination and I recommend used engine oil, Jeyes fluid and L. camara for further testing as they showed some efficacy compared to other remedies.
- Full Text:
- Date Issued: 2008
Developing a business model for a community radio station in Port Elizabeth: a case study
- Ngcezula, Anthony Thamsanqa "Delite"
- Authors: Ngcezula, Anthony Thamsanqa "Delite"
- Date: 2008
- Subjects: Radio in community development , Radio broadcasting -- South Africa , Community radio
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8720 , http://hdl.handle.net/10948/906 , Radio in community development , Radio broadcasting -- South Africa , Community radio
- Description: The purpose of this treatise is a development of a suitable model for a community radio station which would lead to operational effectiveness and ensure sustainability. The treatise has three phases namely a theoretical phase, a narration phase and an integration phase. Firstly, in the theoretical phase the research study investigates what the literature review reveals about community radio stations and business models. This treatise argues that a total dependency of community radio stations on donor funding leads to operational ineffectiveness which threatens their sustainability. The treatise also argues that a business model could be adapted for a community radio station by identifying the business issues which the literature review revealed, and use these to deconstruct a theoretical business model. Secondly, in the narrative phase the research study investigates the important business issues for a selected community radio station. The treatise argues the board and management of this selected community radio station revealed additional business issues of operations and gave different ratings to business issues which are important in their operations. Thirdly, in the integration phase, the theoretical model deconstructed in the theoretical phase, was revised by including additional business issues of operations revealed in the narrative phase. The research study concludes that this revised model is a suitable business model for a community radio station and can lead to operational effectiveness and ensure sustainability.
- Full Text:
- Date Issued: 2008
- Authors: Ngcezula, Anthony Thamsanqa "Delite"
- Date: 2008
- Subjects: Radio in community development , Radio broadcasting -- South Africa , Community radio
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8720 , http://hdl.handle.net/10948/906 , Radio in community development , Radio broadcasting -- South Africa , Community radio
- Description: The purpose of this treatise is a development of a suitable model for a community radio station which would lead to operational effectiveness and ensure sustainability. The treatise has three phases namely a theoretical phase, a narration phase and an integration phase. Firstly, in the theoretical phase the research study investigates what the literature review reveals about community radio stations and business models. This treatise argues that a total dependency of community radio stations on donor funding leads to operational ineffectiveness which threatens their sustainability. The treatise also argues that a business model could be adapted for a community radio station by identifying the business issues which the literature review revealed, and use these to deconstruct a theoretical business model. Secondly, in the narrative phase the research study investigates the important business issues for a selected community radio station. The treatise argues the board and management of this selected community radio station revealed additional business issues of operations and gave different ratings to business issues which are important in their operations. Thirdly, in the integration phase, the theoretical model deconstructed in the theoretical phase, was revised by including additional business issues of operations revealed in the narrative phase. The research study concludes that this revised model is a suitable business model for a community radio station and can lead to operational effectiveness and ensure sustainability.
- Full Text:
- Date Issued: 2008
Developing a long-term strategy for a selected small transport entrepreneur
- Authors: Burgins, David Christopher
- Date: 2008
- Subjects: Transportation -- South Africa -- Port Elizabeth -- Planning , Transportation and state -- South Africa -- Port Elizabeth , Transportation -- South Africa -- Port Elizabeth -- Finance
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8714 , http://hdl.handle.net/10948/929 , Transportation -- South Africa -- Port Elizabeth -- Planning , Transportation and state -- South Africa -- Port Elizabeth , Transportation -- South Africa -- Port Elizabeth -- Finance
- Description: South Africa, recognised as a developing economy, is encouraging its citizens to be entrepreneurs through various initiatives and assistance, with a bias towards the previously disadvantage people. This encouragement, from the government, has been taken advantage of by numerous citizens to the detriment of themselves, especially in the transport industry. Kazderich Pro Trans, a small transport entrepreneur, has founded itself based on the notion that businesses will utilize its services frequently based on the preferential treatment, to previously disadvantaged communities. The stakeholders in the transport industry, however is firstly geared towards maintaining their market share in a fiercely competitive industry with arguably an introspective view of the preferential treatment governmental policies. The purpose of this is to research the transport industry and accurately identify the environment the transport businesses operate in, with a view of analysing competencies that attract and retain business. This paper negates the government policy to a minor external environmental factor and argues that the company (Kazderich Pro Trans) should operate on the same principals as its competitors in the transport industry. The important issue being discussed in this research, the long term strategy, is to make small transport entrepreneurs realise that researching and planning their business are more important than starting it. The attraction and retention of clients is the basis of a successful transport business and the analyses of the questionnaire employed are used as guidance in developing the long term strategy.
- Full Text:
- Date Issued: 2008
- Authors: Burgins, David Christopher
- Date: 2008
- Subjects: Transportation -- South Africa -- Port Elizabeth -- Planning , Transportation and state -- South Africa -- Port Elizabeth , Transportation -- South Africa -- Port Elizabeth -- Finance
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8714 , http://hdl.handle.net/10948/929 , Transportation -- South Africa -- Port Elizabeth -- Planning , Transportation and state -- South Africa -- Port Elizabeth , Transportation -- South Africa -- Port Elizabeth -- Finance
- Description: South Africa, recognised as a developing economy, is encouraging its citizens to be entrepreneurs through various initiatives and assistance, with a bias towards the previously disadvantage people. This encouragement, from the government, has been taken advantage of by numerous citizens to the detriment of themselves, especially in the transport industry. Kazderich Pro Trans, a small transport entrepreneur, has founded itself based on the notion that businesses will utilize its services frequently based on the preferential treatment, to previously disadvantaged communities. The stakeholders in the transport industry, however is firstly geared towards maintaining their market share in a fiercely competitive industry with arguably an introspective view of the preferential treatment governmental policies. The purpose of this is to research the transport industry and accurately identify the environment the transport businesses operate in, with a view of analysing competencies that attract and retain business. This paper negates the government policy to a minor external environmental factor and argues that the company (Kazderich Pro Trans) should operate on the same principals as its competitors in the transport industry. The important issue being discussed in this research, the long term strategy, is to make small transport entrepreneurs realise that researching and planning their business are more important than starting it. The attraction and retention of clients is the basis of a successful transport business and the analyses of the questionnaire employed are used as guidance in developing the long term strategy.
- Full Text:
- Date Issued: 2008
Development of a novel in situ CPRG-based biosensor and bioprobe for monitoring coliform β-D-Galactosidase in water polluted by faecal matter
- Authors: Wutor, Victor Collins
- Date: 2008
- Subjects: Biosensors Molecular probes Enterobacteriaceae Feces -- Microbiology Water -- Pollution -- Environmental aspects Environmental monitoring Chromogenic compounds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3944 , http://hdl.handle.net/10962/d1004003
- Description: The ultimate objective of this work was to develop a real-time method for detecting and monitoring β-D-galactosidase as a suitable indicator of the potential presence of total coliform bacteria in water environments. Preliminary comparison of the chromogenic substrate, chlorophenol red β-D-galactopyranoside and the fluorogenic substrate, MuGAL, revealed unreliable results with the fluorogenic technique due to interference from compounds commonly found in environmental water samples. Thus, the chromogenic assay was further explored. Hydrolysis of the chromogenic substrate chlorophenol red β-D-galactopyranoside by β-D-galactosidase to yield chlorophenol red was the basis of this assay. Fundamental studies with chlorophenol red β-Dgalactopyranoside showed that β-D-galactosidase occurs extracellularly and in low concentrations in the polluted water environment. A direct correlation between enzyme activity and an increase in environmental water sample volume, as well as enzyme activity with total coliform colony forming unit counts were observed. Spectrophotometric detection was achieved within a maximum period of 24 h with a limit of detection level of 1 colony forming unit 100 ml[superscript -1]. This enzyme also exhibited physical and kinetic properties different from those of the pure commercially available β-D-galactosidase. Cell permeabilisation was not required for releasing enzymes into the extracellular environment. PEG 20 000 offered the best option for concentrating β-D-galactosidase. The source of β-D-galactosidase in the polluted environmental water samples was confirmed as Escherichia coli through SDS-PAGE, tryptic mapping and MALDI-TOF, thus justifying the further use of this method for detecting and/or monitoring total coliforms. Several compounds and metal ions commonly found in environmental water samples (as well as those used in water treatment processes) did have an effect on β-D-galactosidase. All the divalent cations except Mg [superscript 2+], at the concentrations studied, inhibited the relative activity of β-D-galactosidase in both commercial β-D-galactosidase and environmental samples. Immobilisation of chlorophenol red β-D-galactopyranoside onto a solid support material for the development of a strip bioprobe was unsuccessful, even though the nylon support material yielded some positive results. A monthly (seasonal) variation in β-Dgalactosidase activity from the environmental water samples was observed, with the highest activity coinciding with the highest monthly temperatures. Electro-oxidative detection and/or monitoring of chlorophenol red was possible. Chlorophenol red detection was linear over a wide range of concentrations (0.001-0.01 μg ml[superscript -1]). Interference by chlorophenol red β-D-galactopyranoside in the reduction window affected analysis. A range of phthalocyanine metal complexes were studied in an attempt to reduce fouling and/or increase the sensitivity of the biosensor. The selected phthalocyanine metal complexes were generally sensitive to changes in pH with a reduction in sensitivity from acidic pH to alkaline pH. The tetrasulphonated phthalocyanine metal complex of copper was, however, more stable with a minimum change of sensitivity. The phthalocyanine metal complexes were generally stable to changes in temperature. While only two consecutive scans were possible with the unmodified glassy carbon electrode, 77 consecutive scans were performed successfully with the CuPc-modified glassy carbon electrode. Among the phthalocyanine metal complexes studied, the CuPc-modified glassy carbon electrode therefore provided excellent results for the development of a biosensor. The CuPc modified-glassy carbon electrode detected 1 colony forming unit 100 ml[superscript -1] in 15 minutes, while the plain unmodified glassy carbon electrode required 6 hours to detect the equivalent number of colony forming units. CoPc, ZnPc and CuTSPc required 2, 2.25 and 1.75 h, respectively, to detect the same numbers of colony forming units. The CuPcmodified glassy carbon electrode detected 40 colony forming units 100 ml[superscript -1] instantly. In general, a direct correlation between colony forming units and current generated in the sensor was observed (R2=0.92). A higher correlation coefficient of 0.99 for 0-30 coliform colony forming units 100 ml[superscript -1] was determined. Current was detected in some water samples which did not show any colony forming units on the media, probably due to the phenomenon of viable but non-culturable bacteria, which is the major disadvantage encountered in the use of media for detecting indicator microorganisms. This novel biosensor therefore presents a very robust and sensitive technique for the detection and/or monitoring of coliform bacterial activity in water.
- Full Text:
- Date Issued: 2008
- Authors: Wutor, Victor Collins
- Date: 2008
- Subjects: Biosensors Molecular probes Enterobacteriaceae Feces -- Microbiology Water -- Pollution -- Environmental aspects Environmental monitoring Chromogenic compounds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3944 , http://hdl.handle.net/10962/d1004003
- Description: The ultimate objective of this work was to develop a real-time method for detecting and monitoring β-D-galactosidase as a suitable indicator of the potential presence of total coliform bacteria in water environments. Preliminary comparison of the chromogenic substrate, chlorophenol red β-D-galactopyranoside and the fluorogenic substrate, MuGAL, revealed unreliable results with the fluorogenic technique due to interference from compounds commonly found in environmental water samples. Thus, the chromogenic assay was further explored. Hydrolysis of the chromogenic substrate chlorophenol red β-D-galactopyranoside by β-D-galactosidase to yield chlorophenol red was the basis of this assay. Fundamental studies with chlorophenol red β-Dgalactopyranoside showed that β-D-galactosidase occurs extracellularly and in low concentrations in the polluted water environment. A direct correlation between enzyme activity and an increase in environmental water sample volume, as well as enzyme activity with total coliform colony forming unit counts were observed. Spectrophotometric detection was achieved within a maximum period of 24 h with a limit of detection level of 1 colony forming unit 100 ml[superscript -1]. This enzyme also exhibited physical and kinetic properties different from those of the pure commercially available β-D-galactosidase. Cell permeabilisation was not required for releasing enzymes into the extracellular environment. PEG 20 000 offered the best option for concentrating β-D-galactosidase. The source of β-D-galactosidase in the polluted environmental water samples was confirmed as Escherichia coli through SDS-PAGE, tryptic mapping and MALDI-TOF, thus justifying the further use of this method for detecting and/or monitoring total coliforms. Several compounds and metal ions commonly found in environmental water samples (as well as those used in water treatment processes) did have an effect on β-D-galactosidase. All the divalent cations except Mg [superscript 2+], at the concentrations studied, inhibited the relative activity of β-D-galactosidase in both commercial β-D-galactosidase and environmental samples. Immobilisation of chlorophenol red β-D-galactopyranoside onto a solid support material for the development of a strip bioprobe was unsuccessful, even though the nylon support material yielded some positive results. A monthly (seasonal) variation in β-Dgalactosidase activity from the environmental water samples was observed, with the highest activity coinciding with the highest monthly temperatures. Electro-oxidative detection and/or monitoring of chlorophenol red was possible. Chlorophenol red detection was linear over a wide range of concentrations (0.001-0.01 μg ml[superscript -1]). Interference by chlorophenol red β-D-galactopyranoside in the reduction window affected analysis. A range of phthalocyanine metal complexes were studied in an attempt to reduce fouling and/or increase the sensitivity of the biosensor. The selected phthalocyanine metal complexes were generally sensitive to changes in pH with a reduction in sensitivity from acidic pH to alkaline pH. The tetrasulphonated phthalocyanine metal complex of copper was, however, more stable with a minimum change of sensitivity. The phthalocyanine metal complexes were generally stable to changes in temperature. While only two consecutive scans were possible with the unmodified glassy carbon electrode, 77 consecutive scans were performed successfully with the CuPc-modified glassy carbon electrode. Among the phthalocyanine metal complexes studied, the CuPc-modified glassy carbon electrode therefore provided excellent results for the development of a biosensor. The CuPc modified-glassy carbon electrode detected 1 colony forming unit 100 ml[superscript -1] in 15 minutes, while the plain unmodified glassy carbon electrode required 6 hours to detect the equivalent number of colony forming units. CoPc, ZnPc and CuTSPc required 2, 2.25 and 1.75 h, respectively, to detect the same numbers of colony forming units. The CuPcmodified glassy carbon electrode detected 40 colony forming units 100 ml[superscript -1] instantly. In general, a direct correlation between colony forming units and current generated in the sensor was observed (R2=0.92). A higher correlation coefficient of 0.99 for 0-30 coliform colony forming units 100 ml[superscript -1] was determined. Current was detected in some water samples which did not show any colony forming units on the media, probably due to the phenomenon of viable but non-culturable bacteria, which is the major disadvantage encountered in the use of media for detecting indicator microorganisms. This novel biosensor therefore presents a very robust and sensitive technique for the detection and/or monitoring of coliform bacterial activity in water.
- Full Text:
- Date Issued: 2008