Lurking or listening? an ethnographic study of online and offline student political participation through the #MustFall protests at Rhodes University
- Authors: Govender, Carissa Jade
- Date: 2017
- Subjects: #Feesmustfall , #Rhodesmustfall , Social media -- Political aspects -- South Africa , Social movements -- South Africa , Political participation -- South Africa , Online social networks -- Political aspects -- South Africa , Student movements -- South Africa , Rhodes University -- Students
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/35123 , vital:24330
- Description: The way media is created and consumed plays an important role in political participation as it provides information, guides thinking and allows citizens to make informed political choices. It can also interrogate the status quo and challenge existing systems or power relations. This thesis discusses the use of social media by Rhodes University students in the context of the 2015 #RhodesMustFall and #FeesMustFall protests in South Africa. This thesis interrogates the concept of slacktivism, a term used to describe online or digital activism which is considered to be less active and not as effective as physical activism. Furthermore, the thesis acknowledges that even when digital political participation is recognised, the emphasis and value is placed on those who speak and create content. The thesis examines the notion of participation and what counts as active citizenship. In particular, the majority of social media users who merely lurk and never contribute to content creation or online discussions are further investigated. The qualitative methodological approach used for this thesis involved three parts which looked at student activity on Facebook, student engagement offline, and how students made sense of their online and offline involvement. Firstly, a cyberethnographic investigation was done in order to understand the cyber world in which students are present. Thereafter, a participant observation was carried out to immerse myself in the offline spaces that students engaged in politically, to get a better sense of how their online presence influenced or supplemented their offline activity. Finally, individual interviews were carried out with lurkers to determine why they did not participate in traditional ways, both online and offline. The findings suggest that lurkers are in fact doing more than just being passively present. The high levels of attention paid to content posted by others on social media, as well as the way that the content influences their offline lives suggest that the choice to lurk is far more active than assumed. Students are consciously deciding to lurk for a multitude of reasons, one of which is for the opportunity to learn. Social media is a fast developing; increasingly used form of communication and how political communication across social media platforms is framed affects what we consider to be active engagement. By using theories of listening and emotion talk, the thesis provides new ways of understanding lurking by Rhodes University students on social media, which in turn can lead to better listening, better understanding and greater political participation.
- Full Text:
- Date Issued: 2017
- Authors: Govender, Carissa Jade
- Date: 2017
- Subjects: #Feesmustfall , #Rhodesmustfall , Social media -- Political aspects -- South Africa , Social movements -- South Africa , Political participation -- South Africa , Online social networks -- Political aspects -- South Africa , Student movements -- South Africa , Rhodes University -- Students
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/35123 , vital:24330
- Description: The way media is created and consumed plays an important role in political participation as it provides information, guides thinking and allows citizens to make informed political choices. It can also interrogate the status quo and challenge existing systems or power relations. This thesis discusses the use of social media by Rhodes University students in the context of the 2015 #RhodesMustFall and #FeesMustFall protests in South Africa. This thesis interrogates the concept of slacktivism, a term used to describe online or digital activism which is considered to be less active and not as effective as physical activism. Furthermore, the thesis acknowledges that even when digital political participation is recognised, the emphasis and value is placed on those who speak and create content. The thesis examines the notion of participation and what counts as active citizenship. In particular, the majority of social media users who merely lurk and never contribute to content creation or online discussions are further investigated. The qualitative methodological approach used for this thesis involved three parts which looked at student activity on Facebook, student engagement offline, and how students made sense of their online and offline involvement. Firstly, a cyberethnographic investigation was done in order to understand the cyber world in which students are present. Thereafter, a participant observation was carried out to immerse myself in the offline spaces that students engaged in politically, to get a better sense of how their online presence influenced or supplemented their offline activity. Finally, individual interviews were carried out with lurkers to determine why they did not participate in traditional ways, both online and offline. The findings suggest that lurkers are in fact doing more than just being passively present. The high levels of attention paid to content posted by others on social media, as well as the way that the content influences their offline lives suggest that the choice to lurk is far more active than assumed. Students are consciously deciding to lurk for a multitude of reasons, one of which is for the opportunity to learn. Social media is a fast developing; increasingly used form of communication and how political communication across social media platforms is framed affects what we consider to be active engagement. By using theories of listening and emotion talk, the thesis provides new ways of understanding lurking by Rhodes University students on social media, which in turn can lead to better listening, better understanding and greater political participation.
- Full Text:
- Date Issued: 2017
Spectroscopic and electrochemical characterization of thio binuclear phthalocyanine complexes
- Authors: Makinde, Zainab Olusola
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/59287 , vital:27541
- Description: Expected release date-April 2019
- Full Text:
- Date Issued: 2017
- Authors: Makinde, Zainab Olusola
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/59287 , vital:27541
- Description: Expected release date-April 2019
- Full Text:
- Date Issued: 2017
“She is my sister although she’s got factory faults”: a psychosocial study of Xhosa women’s sister-sister relationships
- Authors: Moifo, Hunadi Senkoane
- Date: 2017
- Subjects: Xhosa (African people) -- Rites and ceremonies , Xhosa (African people) -- Social life and customs , Sisters -- South Africa -- Case studies , Xhosa (African people) -- Psychology , Women, Black -- South Africa -- Eastern Cape -- Psychology , Women, Black -- South Africa -- Eastern Cape -- Case studies
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/4443 , vital:20671
- Description: The current study examines the constructions that Black, Xhosa women from the working class and in middle adulthood draw on to make meaning of their sister-sister relationships. In addition to this, it aims to uncover their motivations for investing in these meanings. It makes use of a psychosocial theoretical framework that draws on discursive psychology and psychoanalysis. Discursive psychology is used to analyse the constructions the participants used to make meaning of their relationship, while psychoanalysis is used to interpret their investments in these constructions. Six participants were interviewed using semi-structured interviews. The findings emphasise the psychosocial nature of the participants’ sisterly relationships, as caught between ‘inner’ world of feelings and emotions and the ‘outer’ world of social practices and expectations. Their narratives pointed to the obligatory nature of the sister-sister relationship, which drives participants to downplay the hatred or dislike that is present in their relationship and to emphasise traditional scripts of helping each other, promoting solidarity amongst sisters and other women. The analysis highlights the ways in which the participants negotiate and express their gender roles through sistering, reinforcing and challenging the traditional view of femininity and as a result providing for multiple femininities. In addition to these, the findings show that women may choose specific narratives to construct their sister-sister relationships as they allow them to feel safe and in control of their lives. Using psychoanalysis alongside discursive psychology enables the findings to illustrate how the participants invest in different constructions of their relationship in ways that are influenced by their values and life histories.
- Full Text:
- Date Issued: 2017
- Authors: Moifo, Hunadi Senkoane
- Date: 2017
- Subjects: Xhosa (African people) -- Rites and ceremonies , Xhosa (African people) -- Social life and customs , Sisters -- South Africa -- Case studies , Xhosa (African people) -- Psychology , Women, Black -- South Africa -- Eastern Cape -- Psychology , Women, Black -- South Africa -- Eastern Cape -- Case studies
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/4443 , vital:20671
- Description: The current study examines the constructions that Black, Xhosa women from the working class and in middle adulthood draw on to make meaning of their sister-sister relationships. In addition to this, it aims to uncover their motivations for investing in these meanings. It makes use of a psychosocial theoretical framework that draws on discursive psychology and psychoanalysis. Discursive psychology is used to analyse the constructions the participants used to make meaning of their relationship, while psychoanalysis is used to interpret their investments in these constructions. Six participants were interviewed using semi-structured interviews. The findings emphasise the psychosocial nature of the participants’ sisterly relationships, as caught between ‘inner’ world of feelings and emotions and the ‘outer’ world of social practices and expectations. Their narratives pointed to the obligatory nature of the sister-sister relationship, which drives participants to downplay the hatred or dislike that is present in their relationship and to emphasise traditional scripts of helping each other, promoting solidarity amongst sisters and other women. The analysis highlights the ways in which the participants negotiate and express their gender roles through sistering, reinforcing and challenging the traditional view of femininity and as a result providing for multiple femininities. In addition to these, the findings show that women may choose specific narratives to construct their sister-sister relationships as they allow them to feel safe and in control of their lives. Using psychoanalysis alongside discursive psychology enables the findings to illustrate how the participants invest in different constructions of their relationship in ways that are influenced by their values and life histories.
- Full Text:
- Date Issued: 2017
Visual narratives of division in contemporary Palestinian art and social space
- Authors: Baasch, Rachel Mary
- Date: 2017
- Subjects: Art, Palestinian Arab , Art, Palestinian Arab -- Political aspects , Art and society -- Palestine
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/41770 , vital:25132
- Description: This study analyses artworks by contemporary Palestinian artists that respond to visual narratives of division in social space from a perspective grounded in a South African context. The state of Israel is built on Historic Palestine. Political Zionism has created an ideological narrative of division that positions people of the Jewish faith as the rightful heirs to the land on which Palestinians have lived for centuries. In order to execute their vision of an exclusively Jewish nation state, the founding pioneers of political Zionism colonised and ethnically cleansed Historic Palestine, establishing Israel in 1948. To sustain the exclusive claim to Palestinian land, Israel has divided the space and the people in it at every possible level. The greatest testament to these efforts is the Israeli apartheid wall and checkpoint security system that can be described as a monumental visual narrative of division. With each second that passes, Israel claims more Palestinian land and expands on existing fences, walls and barriers. It is no secret that the Occupied Palestinian Territories are rapidly transforming into open-air prisons. Israel has stolen the Palestinian horizon line and replaced it with a concrete wall that blocks out light, vision and optimism. Within the shadows of these conflicted, traumatised sites of division, Palestinian artists seek openings, cracks and loopholes that signal the possibility for physical and psychological transgression of these seemingly impenetrable structures of division. I have developed a creative methodology that can be understood through the metaphor of ‘looking with the skin’ as a way to identify and analyse visual narratives of division and artistic responses to sites of division in Palestinian social space. Looking with the skin combines aspects of participant observation (specifically the emphasis on engaged fieldwork) from the discipline of Anthropology with the method of visual analysis from the discipline of Art History. In my application of this method through primary fieldwork conducted within the Occupied Palestinian West Bank Territory from 2013 and 2014, I have learnt that Israel’s colonisation, military occupation and system of apartheid directly impacts the ability of Palestinian artists to make and disseminate their work as well as the choice of content within their artwork. The artworks analysed in this thesis by the artists Khaled Jarrar, Y ael Bartana, Larissa Sansour, Hasan Darahgmeh, Fareh Saleh and Emily Jacir can be positioned in relation to artworks by artists based within a South African context, namely Thando Mama, Serge Alain Nitegeka and Doung Anwar Jahangeer. In this thesis I present a combination of my own photographic documentation of sites of division with the West Bank OPT in relation to the specific artworks made by the artists mentioned above. In my analysis of the photographic documentation and the artists’ work I highlight similarities, parallels, threads and intersecting narratives that connect different artists to one another and to the sites of division they are responding to within their artistic practice. This study carves a small conceptual pathway through ideological and physical walls from South Africa to Palestine through the study of contemporary art and visual culture.
- Full Text:
- Date Issued: 2017
- Authors: Baasch, Rachel Mary
- Date: 2017
- Subjects: Art, Palestinian Arab , Art, Palestinian Arab -- Political aspects , Art and society -- Palestine
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/41770 , vital:25132
- Description: This study analyses artworks by contemporary Palestinian artists that respond to visual narratives of division in social space from a perspective grounded in a South African context. The state of Israel is built on Historic Palestine. Political Zionism has created an ideological narrative of division that positions people of the Jewish faith as the rightful heirs to the land on which Palestinians have lived for centuries. In order to execute their vision of an exclusively Jewish nation state, the founding pioneers of political Zionism colonised and ethnically cleansed Historic Palestine, establishing Israel in 1948. To sustain the exclusive claim to Palestinian land, Israel has divided the space and the people in it at every possible level. The greatest testament to these efforts is the Israeli apartheid wall and checkpoint security system that can be described as a monumental visual narrative of division. With each second that passes, Israel claims more Palestinian land and expands on existing fences, walls and barriers. It is no secret that the Occupied Palestinian Territories are rapidly transforming into open-air prisons. Israel has stolen the Palestinian horizon line and replaced it with a concrete wall that blocks out light, vision and optimism. Within the shadows of these conflicted, traumatised sites of division, Palestinian artists seek openings, cracks and loopholes that signal the possibility for physical and psychological transgression of these seemingly impenetrable structures of division. I have developed a creative methodology that can be understood through the metaphor of ‘looking with the skin’ as a way to identify and analyse visual narratives of division and artistic responses to sites of division in Palestinian social space. Looking with the skin combines aspects of participant observation (specifically the emphasis on engaged fieldwork) from the discipline of Anthropology with the method of visual analysis from the discipline of Art History. In my application of this method through primary fieldwork conducted within the Occupied Palestinian West Bank Territory from 2013 and 2014, I have learnt that Israel’s colonisation, military occupation and system of apartheid directly impacts the ability of Palestinian artists to make and disseminate their work as well as the choice of content within their artwork. The artworks analysed in this thesis by the artists Khaled Jarrar, Y ael Bartana, Larissa Sansour, Hasan Darahgmeh, Fareh Saleh and Emily Jacir can be positioned in relation to artworks by artists based within a South African context, namely Thando Mama, Serge Alain Nitegeka and Doung Anwar Jahangeer. In this thesis I present a combination of my own photographic documentation of sites of division with the West Bank OPT in relation to the specific artworks made by the artists mentioned above. In my analysis of the photographic documentation and the artists’ work I highlight similarities, parallels, threads and intersecting narratives that connect different artists to one another and to the sites of division they are responding to within their artistic practice. This study carves a small conceptual pathway through ideological and physical walls from South Africa to Palestine through the study of contemporary art and visual culture.
- Full Text:
- Date Issued: 2017
Teachers’ use of situated learning approaches to teach environmental topics in Natural Science and Health Education: a multi-case study of two Namibian teachers
- Authors: Mamili, Joy Z
- Date: 2017
- Subjects: Environmental education -- Namibia , Science -- Study and teaching -- Namibia -- Cast studies , Health education -- Namibia -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/40901 , vital:25037
- Description: This study focuses on the use of situated learning approaches in the teaching of environmental topics in Natural Science and Health Education (NSHED) and is the first of its kind in Namibia. Although situated learning approaches, as examples of learner-centred pedagogy, are advocated in national education policies, little empirical research has been conducted in Namibia into how situated learning approaches play out in classroom practice. Therefore, the goal of this study was to find out how NSHED teachers use situated learning approaches when teaching environmental topics. The study reviews the characteristics of situated learning theory and clarifies situated learning approaches as a form of learner-centred pedagogy which is actively promoted in the Namibian schooling system. The study commences with a contextual profile of the communities around the two selected schools. This describes the socio-economic and social-ecological context in which learners are taught about environmental topics. The profile also describes the under-performance of the schools in recent national assessments, especially in relation to environmental topics in NSHED. Drawing on data generated through document analysis, semi-structured interviews and classroom observations, the study concluded that: 1. NSHED teachers both knew about and wished to create an authentic context to enhance situated learning approaches. However, their understandings and applications of situated learning tended to be basic. 2. Teachers dominated the scaffolding process and their scaffolding strategies did not enable learners to increase independence in performing. 3. Despite the use of situated learning approaches, learners’ engagement with lesson content was superficial, and the teachers did little to encourage deeper reflections or critical thinking. 4. The teachers appeared to use situated learning approaches to clarify subject content but not to encourage broader environmental understanding, action-taking and change. Based on the research findings, the study recommends that situated learning approaches be integrated into pre- and in-service teacher training with the aim of enhancing teachers’ understanding regarding the use of situated learning approaches in the teaching of environmental topics in NSHED.
- Full Text:
- Date Issued: 2017
- Authors: Mamili, Joy Z
- Date: 2017
- Subjects: Environmental education -- Namibia , Science -- Study and teaching -- Namibia -- Cast studies , Health education -- Namibia -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/40901 , vital:25037
- Description: This study focuses on the use of situated learning approaches in the teaching of environmental topics in Natural Science and Health Education (NSHED) and is the first of its kind in Namibia. Although situated learning approaches, as examples of learner-centred pedagogy, are advocated in national education policies, little empirical research has been conducted in Namibia into how situated learning approaches play out in classroom practice. Therefore, the goal of this study was to find out how NSHED teachers use situated learning approaches when teaching environmental topics. The study reviews the characteristics of situated learning theory and clarifies situated learning approaches as a form of learner-centred pedagogy which is actively promoted in the Namibian schooling system. The study commences with a contextual profile of the communities around the two selected schools. This describes the socio-economic and social-ecological context in which learners are taught about environmental topics. The profile also describes the under-performance of the schools in recent national assessments, especially in relation to environmental topics in NSHED. Drawing on data generated through document analysis, semi-structured interviews and classroom observations, the study concluded that: 1. NSHED teachers both knew about and wished to create an authentic context to enhance situated learning approaches. However, their understandings and applications of situated learning tended to be basic. 2. Teachers dominated the scaffolding process and their scaffolding strategies did not enable learners to increase independence in performing. 3. Despite the use of situated learning approaches, learners’ engagement with lesson content was superficial, and the teachers did little to encourage deeper reflections or critical thinking. 4. The teachers appeared to use situated learning approaches to clarify subject content but not to encourage broader environmental understanding, action-taking and change. Based on the research findings, the study recommends that situated learning approaches be integrated into pre- and in-service teacher training with the aim of enhancing teachers’ understanding regarding the use of situated learning approaches in the teaching of environmental topics in NSHED.
- Full Text:
- Date Issued: 2017
The development, manufacture and characterisation of niosomes intended to deliver nevirapine to the brain
- Authors: Witika, Bwalya Angel
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/65257 , vital:28715
- Description: Expected release date-May 2019
- Full Text:
- Date Issued: 2017
- Authors: Witika, Bwalya Angel
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/65257 , vital:28715
- Description: Expected release date-May 2019
- Full Text:
- Date Issued: 2017
Assessing MODIS evapotranspiration data for hydrological modelling in South Africa
- Mazibuko, Sbongiseni Christian
- Authors: Mazibuko, Sbongiseni Christian
- Date: 2017
- Subjects: Evapotranspiration , Evapotranspiration -- Measurement , Hydrologic models , Hydrologic models -- South Africa , MODIS (Spectroradiometer)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/8009 , vital:21334
- Description: Evapotranspiration as a major component of the water balance has been identified as a key factor in hydrological modelling. Water management can be improved by means of increased use of reliable methods for estimating evapotranspiration. The limited availability of measured climate and discharge data sets, particularly in the developing world, restricts the reliability of hydrological models in these regions. Furthermore, rapid changes in hydrological systems with increasing development mean uncertainties in water resource estimation are growing. These changes are related to the modification of catchment hydrological processes with increasing human activity. Dealing with data uncertainty and quantifying the impacts of catchment activities are significant challenges that scientists in the field of hydrology face today. Uncertainties in hydrometeorological data are associated with poor observation networks that provide data at point scales which are not adequately representative of the inherent heterogeneity within catchment processes. Using uncertain data in model applications reduces the predictive power of hydrological models as well as the ability to validate the model outcomes. This study examines the potential of using remote sensing-based evapotranspiration data to reduce uncertainty in the climatic forcing data and constraining the output of a rainfall-runoff hydrological model. It is common to use fixed seasonally variable potential evapotranspiration (PET) instead of temporally varying PET data as inputs to standard rainfall-runoff models. Part of the reason is that there are relatively few stations available to measure a variety of meteorological input data needed to compute PET, as well as the apparent lack of sensitivity of rainfall-runoff models to different types of PET inputs. As hydrometeorological data become more readily available through the use of earth observation systems, it is important to determine whether rainfall-runoff models are sensitive to time-varying PET derived from these earth observations systems. Further potential includes the use of actual evapotranspiration (ETa) from this type of data to constrain model outputs and improve model realism. It is assumed that a better representation of evapotranspiration demands could improve the efficiency of models, and this study explores some of these issues. The study used evapotranspiration estimates (PET and ETa) from the MOD16 global product with one of the most widely used hydrological models in South Africa. The investigation included applying the Pitman model in a number of case study catchments located in different climatic regions of the country. The main objectives of the study included (i) the establishment of behavioural model parameter sets that generate acceptable hydrological response under both naturalised and present-day conditions, (ii) the use of time-varying PET estimates derived from MOD16 data to force the model, and (iii) the use of MOD16 ETa estimates to constrain model-simulated ETa. Before examining the use of different PET forcing data in the model, a two-step modelling approached was employed both a single-run and an uncertainty version of the Pitman model. During the first step (using a single-run version), available information on catchment physical properties and regionalised groundwater recharge together with model calibration principles were used to develop model functionality understanding and establish initial parameter sets. The outcomes from the first step were used to define uncertain parameter ranges for the use in the uncertainty version of the Pitman model (second step). Further, catchment water uses were quantified to ensure comparability with present-day flow conditions represented by the stream flow records. The effects of forcing the Pitman model with MOD16-based time-varying PET data inputs were evaluated using static and dynamic sensitivity analysis approaches. In the static approach, parameter sets calibrated using fixed seasonal distributions of PET data remain unchanged when forcing the model with other forms of PET, whereas in the dynamic method, the model is recalibrated with changing PET inputs. In both approaches, model sensitivity was assessed by comparing objective function statistics of reference flow simulations with those simulations incorporating changing PET data inputs. The use of the MOD16 ETa data to constrain model- simulated evapotranspiration losses was conducted by calibrating the parameters such that the simulated-ETa matched the evapotranspiration loss estimated from the MOD16 data. Despite issues around model equifinality and significant uncertainty within water use information, the Pitman model simulations were generally satisfactory and compared with observed stream flow data where available. The use of time-varying PET data does not improve the efficiency of the model when both static and dynamic sensitivity approaches are used. This was highly expected with the static approach where fixed model parameter sets do not account for the changes in evapotranspiration demands. However, with the dynamic approach, it was difficult to conclude why the model efficiency did not improve given the flexibility of the model to achieve appropriate parameter sets to different forms of PET. The study noted that the insensitivity of the model to changes in PET demands could be due to uncertainties in the model structure and MOD16 data. Attempts to constrain the model-simulated actual evapotranspiration with MOD16 ETa estimates were hampered by large errors in the MOD16 data and resulted in the non-closure of the catchment annual water balance, even when likely errors in the other components of the water balance were accounted for. There is still a great deal of work that needs to be done to reduce uncertainties associated with the use of earth observation data in hydrological modelling. This study has identified some of the specific gaps within the application of evapotranspiration data from earth observation information. While the MOD16 data applied with the Pitman model did not achieve improved simulations, the study has demonstrated the enormous potential of the data product in the future should the identified uncertainties be resolved. Lastly, the investigation highlighted some of the possible model structural uncertainties specifically associated with the simplified soil-moisture accounting routines within the model. It is possible that amending the model structure through investigating the dynamics of the relationship between soil moisture and evapotranspiration losses would assist in the improved utilisation of earth observation products related to the MOD16 ET data.
- Full Text:
- Date Issued: 2017
- Authors: Mazibuko, Sbongiseni Christian
- Date: 2017
- Subjects: Evapotranspiration , Evapotranspiration -- Measurement , Hydrologic models , Hydrologic models -- South Africa , MODIS (Spectroradiometer)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/8009 , vital:21334
- Description: Evapotranspiration as a major component of the water balance has been identified as a key factor in hydrological modelling. Water management can be improved by means of increased use of reliable methods for estimating evapotranspiration. The limited availability of measured climate and discharge data sets, particularly in the developing world, restricts the reliability of hydrological models in these regions. Furthermore, rapid changes in hydrological systems with increasing development mean uncertainties in water resource estimation are growing. These changes are related to the modification of catchment hydrological processes with increasing human activity. Dealing with data uncertainty and quantifying the impacts of catchment activities are significant challenges that scientists in the field of hydrology face today. Uncertainties in hydrometeorological data are associated with poor observation networks that provide data at point scales which are not adequately representative of the inherent heterogeneity within catchment processes. Using uncertain data in model applications reduces the predictive power of hydrological models as well as the ability to validate the model outcomes. This study examines the potential of using remote sensing-based evapotranspiration data to reduce uncertainty in the climatic forcing data and constraining the output of a rainfall-runoff hydrological model. It is common to use fixed seasonally variable potential evapotranspiration (PET) instead of temporally varying PET data as inputs to standard rainfall-runoff models. Part of the reason is that there are relatively few stations available to measure a variety of meteorological input data needed to compute PET, as well as the apparent lack of sensitivity of rainfall-runoff models to different types of PET inputs. As hydrometeorological data become more readily available through the use of earth observation systems, it is important to determine whether rainfall-runoff models are sensitive to time-varying PET derived from these earth observations systems. Further potential includes the use of actual evapotranspiration (ETa) from this type of data to constrain model outputs and improve model realism. It is assumed that a better representation of evapotranspiration demands could improve the efficiency of models, and this study explores some of these issues. The study used evapotranspiration estimates (PET and ETa) from the MOD16 global product with one of the most widely used hydrological models in South Africa. The investigation included applying the Pitman model in a number of case study catchments located in different climatic regions of the country. The main objectives of the study included (i) the establishment of behavioural model parameter sets that generate acceptable hydrological response under both naturalised and present-day conditions, (ii) the use of time-varying PET estimates derived from MOD16 data to force the model, and (iii) the use of MOD16 ETa estimates to constrain model-simulated ETa. Before examining the use of different PET forcing data in the model, a two-step modelling approached was employed both a single-run and an uncertainty version of the Pitman model. During the first step (using a single-run version), available information on catchment physical properties and regionalised groundwater recharge together with model calibration principles were used to develop model functionality understanding and establish initial parameter sets. The outcomes from the first step were used to define uncertain parameter ranges for the use in the uncertainty version of the Pitman model (second step). Further, catchment water uses were quantified to ensure comparability with present-day flow conditions represented by the stream flow records. The effects of forcing the Pitman model with MOD16-based time-varying PET data inputs were evaluated using static and dynamic sensitivity analysis approaches. In the static approach, parameter sets calibrated using fixed seasonal distributions of PET data remain unchanged when forcing the model with other forms of PET, whereas in the dynamic method, the model is recalibrated with changing PET inputs. In both approaches, model sensitivity was assessed by comparing objective function statistics of reference flow simulations with those simulations incorporating changing PET data inputs. The use of the MOD16 ETa data to constrain model- simulated evapotranspiration losses was conducted by calibrating the parameters such that the simulated-ETa matched the evapotranspiration loss estimated from the MOD16 data. Despite issues around model equifinality and significant uncertainty within water use information, the Pitman model simulations were generally satisfactory and compared with observed stream flow data where available. The use of time-varying PET data does not improve the efficiency of the model when both static and dynamic sensitivity approaches are used. This was highly expected with the static approach where fixed model parameter sets do not account for the changes in evapotranspiration demands. However, with the dynamic approach, it was difficult to conclude why the model efficiency did not improve given the flexibility of the model to achieve appropriate parameter sets to different forms of PET. The study noted that the insensitivity of the model to changes in PET demands could be due to uncertainties in the model structure and MOD16 data. Attempts to constrain the model-simulated actual evapotranspiration with MOD16 ETa estimates were hampered by large errors in the MOD16 data and resulted in the non-closure of the catchment annual water balance, even when likely errors in the other components of the water balance were accounted for. There is still a great deal of work that needs to be done to reduce uncertainties associated with the use of earth observation data in hydrological modelling. This study has identified some of the specific gaps within the application of evapotranspiration data from earth observation information. While the MOD16 data applied with the Pitman model did not achieve improved simulations, the study has demonstrated the enormous potential of the data product in the future should the identified uncertainties be resolved. Lastly, the investigation highlighted some of the possible model structural uncertainties specifically associated with the simplified soil-moisture accounting routines within the model. It is possible that amending the model structure through investigating the dynamics of the relationship between soil moisture and evapotranspiration losses would assist in the improved utilisation of earth observation products related to the MOD16 ET data.
- Full Text:
- Date Issued: 2017
Missing values: a closer look
- Authors: Thorpe, Kerri
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/d1017827 , vital:20798
- Description: Problem: In today’s world, missing values are more present than ever. Due to the ever-changing and fast paced global society in which we live, most business and research data produced around the world contain missing data. This means that locating data which is meticulously precise can be a hard task in itself, but at times may prove essential as the consequences of making use of incomplete data could be disastrous. The reasons for missing data cropping up in almost all forms of work are numerous and shall be discussed in this dissertation. For example, those being interviewed or polled may choose to simply ignore questions which are posed to them, recording equipment may malfunction or be misplaced, or organisers may not be able to locate the respondent in order to rectify the missing data. Whatever the reasons for data being incomplete, it is necessary to avoid having to use inefficient and incomplete data as a result from the above problems. Therefore, various strategies or methods have been developed in order to handle these missing values. It is important, however, that these strategies or methods are utilised effectively as missing data treatment can introduce bias into the analysis. This dissertation shall look at these and other problems in more detail by using a data set which consists of records for 581 children who were interviewed in 1990 as part of the National Longitudinal Survey of Youth (NLSY). Approach: As mentioned above, many strategies or methods have been developed in order to deal with missing values. More specifically, traditional methods such as complete case analysis, available case analysis or single imputation are widely used by researchers and shall be discussed herein. Although these methods are simple and easy to implement, they require assumptions about the data that are not often satisfied in practice. Over the years, more up to date and relevant methods, such as multiple imputation and maximum likelihood have been developed. These methods rely on weaker assumptions and contain superior statistical properties when compared to the traditional techniques. In this dissertation, these traditional methods shall be reviewed and assessed in SAS and shall be compared to the more modern techniques. Results: The ad hoc techniques for handling missing data such as complete case and available case methods produce biased parameter estimates when the data is not missing completely at random (MCAR). Single imputation techniques likewise produce biased estimates as well as result in the underestimation of standard errors. Although the expectation maximisation (EM) algorithm yields unbiased parameter estimates, the lack of convenient standard errors suggests that using this algorithm for hypothesis testing is not a good idea. Multiple imputation, however, yields unbiased parameter estimates and correctly estimates standard errors. Conclusion: Ignoring missing data in any analysis produces biased parameter estimates. Using single imputation to handle missing values is not recommended, as using a single value to replace missing values does not account for the variation that would have been present if the variables were observed. As a result, the variance will be greatly underestimated. The more modern missing data methods such as the EM algorithm and multiple imputation are preferred over the traditional techniques as they require less stringent assumptions and they also mitigate the downsides of the older methods.
- Full Text:
- Date Issued: 2017
- Authors: Thorpe, Kerri
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/d1017827 , vital:20798
- Description: Problem: In today’s world, missing values are more present than ever. Due to the ever-changing and fast paced global society in which we live, most business and research data produced around the world contain missing data. This means that locating data which is meticulously precise can be a hard task in itself, but at times may prove essential as the consequences of making use of incomplete data could be disastrous. The reasons for missing data cropping up in almost all forms of work are numerous and shall be discussed in this dissertation. For example, those being interviewed or polled may choose to simply ignore questions which are posed to them, recording equipment may malfunction or be misplaced, or organisers may not be able to locate the respondent in order to rectify the missing data. Whatever the reasons for data being incomplete, it is necessary to avoid having to use inefficient and incomplete data as a result from the above problems. Therefore, various strategies or methods have been developed in order to handle these missing values. It is important, however, that these strategies or methods are utilised effectively as missing data treatment can introduce bias into the analysis. This dissertation shall look at these and other problems in more detail by using a data set which consists of records for 581 children who were interviewed in 1990 as part of the National Longitudinal Survey of Youth (NLSY). Approach: As mentioned above, many strategies or methods have been developed in order to deal with missing values. More specifically, traditional methods such as complete case analysis, available case analysis or single imputation are widely used by researchers and shall be discussed herein. Although these methods are simple and easy to implement, they require assumptions about the data that are not often satisfied in practice. Over the years, more up to date and relevant methods, such as multiple imputation and maximum likelihood have been developed. These methods rely on weaker assumptions and contain superior statistical properties when compared to the traditional techniques. In this dissertation, these traditional methods shall be reviewed and assessed in SAS and shall be compared to the more modern techniques. Results: The ad hoc techniques for handling missing data such as complete case and available case methods produce biased parameter estimates when the data is not missing completely at random (MCAR). Single imputation techniques likewise produce biased estimates as well as result in the underestimation of standard errors. Although the expectation maximisation (EM) algorithm yields unbiased parameter estimates, the lack of convenient standard errors suggests that using this algorithm for hypothesis testing is not a good idea. Multiple imputation, however, yields unbiased parameter estimates and correctly estimates standard errors. Conclusion: Ignoring missing data in any analysis produces biased parameter estimates. Using single imputation to handle missing values is not recommended, as using a single value to replace missing values does not account for the variation that would have been present if the variables were observed. As a result, the variance will be greatly underestimated. The more modern missing data methods such as the EM algorithm and multiple imputation are preferred over the traditional techniques as they require less stringent assumptions and they also mitigate the downsides of the older methods.
- Full Text:
- Date Issued: 2017
Molecular cloning and expression of equine CYP1A2 in Escherichia coli
- Authors: Mkabayi, Lithalethu
- Date: 2017
- Subjects: Escherichia coli , Escherichia coli infections in animals , Cytochrome P-450 , Cytochromes , Horses -- Effect of drugs on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4830 , vital:20734
- Description: Information regarding drug metabolism in veterinary species, especially horses, remains fragmented and incomplete. This information is essential for detection of metabolites of potential performance-enhancing substances in horseracing and for veterinary drug development. Equine liver microsomes have been used to study metabolism of a limited number of drugs, but these provide little information about individual drug metabolizing enzymes. Recombinant CYP enzyme systems are commonly used to determine contribution of individual CYP to metabolism of specific drugs. A limited number of recombinant equine CYPs have been expressed in insect cells and mammalian cell lines. However, there are no reports of recombinant equine CYP1A2 enzyme. In this study, equine CYP1A2 was identified, codon-optimized, cloned and expressed in E. coli BL21 cells. Multiple sequence alignments of equine CYP1A2 revealed an amino acid sequence identity of 83.69% to its human homolog which has previously been expressed in E. coli. The enzyme was expressed using both auto-induction and IPTG induction. Expressed equine CYP1A2 had a size of about 55 kDa, and was insoluble after cell lysis. Sarkosyl- solubilized CYP1A2 was purified using nickel affinity chromatography and gel filtration. For activity reconstitution, yeast NADPH-cytochrome P450 reductase was first expressed in E. coli BL21 cells and exhibited activity of 0.13 U/ml. Activity assay with Glo-P450 CYP1A2 assay kit indicated that CYP1A2 was inactive. Despite numerous attempts to obtain the activity, the CYP1A2 remained inactive. Although expression of equine CYP1A2 in E. coli produced non- catalytically active enzyme, this study could be used as the first step in an effort to fully develop a recombinant equine CYP1A2 system.
- Full Text:
- Date Issued: 2017
- Authors: Mkabayi, Lithalethu
- Date: 2017
- Subjects: Escherichia coli , Escherichia coli infections in animals , Cytochrome P-450 , Cytochromes , Horses -- Effect of drugs on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4830 , vital:20734
- Description: Information regarding drug metabolism in veterinary species, especially horses, remains fragmented and incomplete. This information is essential for detection of metabolites of potential performance-enhancing substances in horseracing and for veterinary drug development. Equine liver microsomes have been used to study metabolism of a limited number of drugs, but these provide little information about individual drug metabolizing enzymes. Recombinant CYP enzyme systems are commonly used to determine contribution of individual CYP to metabolism of specific drugs. A limited number of recombinant equine CYPs have been expressed in insect cells and mammalian cell lines. However, there are no reports of recombinant equine CYP1A2 enzyme. In this study, equine CYP1A2 was identified, codon-optimized, cloned and expressed in E. coli BL21 cells. Multiple sequence alignments of equine CYP1A2 revealed an amino acid sequence identity of 83.69% to its human homolog which has previously been expressed in E. coli. The enzyme was expressed using both auto-induction and IPTG induction. Expressed equine CYP1A2 had a size of about 55 kDa, and was insoluble after cell lysis. Sarkosyl- solubilized CYP1A2 was purified using nickel affinity chromatography and gel filtration. For activity reconstitution, yeast NADPH-cytochrome P450 reductase was first expressed in E. coli BL21 cells and exhibited activity of 0.13 U/ml. Activity assay with Glo-P450 CYP1A2 assay kit indicated that CYP1A2 was inactive. Despite numerous attempts to obtain the activity, the CYP1A2 remained inactive. Although expression of equine CYP1A2 in E. coli produced non- catalytically active enzyme, this study could be used as the first step in an effort to fully develop a recombinant equine CYP1A2 system.
- Full Text:
- Date Issued: 2017
Data compression, field of interest shaping and fast algorithms for direction-dependent deconvolution in radio interferometry
- Authors: Atemkeng, Marcellin T
- Date: 2017
- Subjects: Radio astronomy , Solar radio emission , Radio interferometers , Signal processing -- Digital techniques , Algorithms , Data compression (Computer science)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/6324 , vital:21089
- Description: In radio interferometry, observed visibilities are intrinsically sampled at some interval in time and frequency. Modern interferometers are capable of producing data at very high time and frequency resolution; practical limits on storage and computation costs require that some form of data compression be imposed. The traditional form of compression is simple averaging of the visibilities over coarser time and frequency bins. This has an undesired side effect: the resulting averaged visibilities “decorrelate”, and do so differently depending on the baseline length and averaging interval. This translates into a non-trivial signature in the image domain known as “smearing”, which manifests itself as an attenuation in amplitude towards off-centre sources. With the increasing fields of view and/or longer baselines employed in modern and future instruments, the trade-off between data rate and smearing becomes increasingly unfavourable. Averaging also results in baseline length and a position-dependent point spread function (PSF). In this work, we investigate alternative approaches to low-loss data compression. We show that averaging of the visibility data can be understood as a form of convolution by a boxcar-like window function, and that by employing alternative baseline-dependent window functions a more optimal interferometer smearing response may be induced. Specifically, we can improve amplitude response over a chosen field of interest and attenuate sources outside the field of interest. The main cost of this technique is a reduction in nominal sensitivity; we investigate the smearing vs. sensitivity trade-off and show that in certain regimes a favourable compromise can be achieved. We show the application of this technique to simulated data from the Jansky Very Large Array and the European Very Long Baseline Interferometry Network. Furthermore, we show that the position-dependent PSF shape induced by averaging can be approximated using linear algebraic properties to effectively reduce the computational complexity for evaluating the PSF at each sky position. We conclude by implementing a position-dependent PSF deconvolution in an imaging and deconvolution framework. Using the Low-Frequency Array radio interferometer, we show that deconvolution with position-dependent PSFs results in higher image fidelity compared to a simple CLEAN algorithm and its derivatives.
- Full Text:
- Date Issued: 2017
- Authors: Atemkeng, Marcellin T
- Date: 2017
- Subjects: Radio astronomy , Solar radio emission , Radio interferometers , Signal processing -- Digital techniques , Algorithms , Data compression (Computer science)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/6324 , vital:21089
- Description: In radio interferometry, observed visibilities are intrinsically sampled at some interval in time and frequency. Modern interferometers are capable of producing data at very high time and frequency resolution; practical limits on storage and computation costs require that some form of data compression be imposed. The traditional form of compression is simple averaging of the visibilities over coarser time and frequency bins. This has an undesired side effect: the resulting averaged visibilities “decorrelate”, and do so differently depending on the baseline length and averaging interval. This translates into a non-trivial signature in the image domain known as “smearing”, which manifests itself as an attenuation in amplitude towards off-centre sources. With the increasing fields of view and/or longer baselines employed in modern and future instruments, the trade-off between data rate and smearing becomes increasingly unfavourable. Averaging also results in baseline length and a position-dependent point spread function (PSF). In this work, we investigate alternative approaches to low-loss data compression. We show that averaging of the visibility data can be understood as a form of convolution by a boxcar-like window function, and that by employing alternative baseline-dependent window functions a more optimal interferometer smearing response may be induced. Specifically, we can improve amplitude response over a chosen field of interest and attenuate sources outside the field of interest. The main cost of this technique is a reduction in nominal sensitivity; we investigate the smearing vs. sensitivity trade-off and show that in certain regimes a favourable compromise can be achieved. We show the application of this technique to simulated data from the Jansky Very Large Array and the European Very Long Baseline Interferometry Network. Furthermore, we show that the position-dependent PSF shape induced by averaging can be approximated using linear algebraic properties to effectively reduce the computational complexity for evaluating the PSF at each sky position. We conclude by implementing a position-dependent PSF deconvolution in an imaging and deconvolution framework. Using the Low-Frequency Array radio interferometer, we show that deconvolution with position-dependent PSFs results in higher image fidelity compared to a simple CLEAN algorithm and its derivatives.
- Full Text:
- Date Issued: 2017
Experiences of having an adult sibling with a mental illness: an interpretative phenomenological analysis
- Authors: Flannigan, Raylene
- Date: 2017
- Subjects: Mentally ill -- Family relationships , Mentally ill -- Care -- South Africa , Mental illness -- Public opinion -- South Africa , Mentally ill -- Deinstitutionalization , Brothers and sisters of people with disabilities , Brothers and sisters of people with disabilities -- Psycnology , Brothers and sisters of people with disabilities -- Case studies -- South Africa -- Makhanda
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/6309 , vital:21088
- Description: Mental illness has a significant impact on the life of an individual, however not only on the individual but on the family as well. A considerable amount of research has been carried out regarding the experiences of family members internationally. However, in South Africa (SA) there is inadequate information regarding the experiences of families, especially adult siblings, of individuals with a mental illness. Specifically, there is a lack of research investigating individuals’ perceptions of their brother or sister’s mental illness as well as how this affects the sibling relationship. It is for this reason that the current study aimed at exploring the lived experiences of ‘black1’ isiXhosa speaking individuals who have a sibling with a mental illness. The study employed Interpretative Phenomenological Analysis (IPA) as its qualitative approach. A sample of five participants between the ages of 20-50 years was selected through purposive and snowballing sampling techniques. Semi-structured interviews were utilised and were transcribed and analysed based on the IPA framework. The analysis of the participants’ transcripts provided three master themes, which are supported by subordinate themes. The master themes are: 1) experiencing the sibling as a burden post diagnosis, 2) positive experiences from the sibling’s mental illness, 3) participant’s experiences of their sibling’s treatment and the mental health care system. Participants experienced financial burden as well as the burden of caregiving as a result of their sibling’s mental illness; these are understood as being subjective and objective burdens. While no change was experienced within the sibling relationship, the siblings’ mental illness was experienced as affecting the sibling relationship due to the socioeconomic status of the participants and stigma. The findings support and expand on the growing knowledge of adult sibling relationships and mental illness.
- Full Text:
- Date Issued: 2017
- Authors: Flannigan, Raylene
- Date: 2017
- Subjects: Mentally ill -- Family relationships , Mentally ill -- Care -- South Africa , Mental illness -- Public opinion -- South Africa , Mentally ill -- Deinstitutionalization , Brothers and sisters of people with disabilities , Brothers and sisters of people with disabilities -- Psycnology , Brothers and sisters of people with disabilities -- Case studies -- South Africa -- Makhanda
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/6309 , vital:21088
- Description: Mental illness has a significant impact on the life of an individual, however not only on the individual but on the family as well. A considerable amount of research has been carried out regarding the experiences of family members internationally. However, in South Africa (SA) there is inadequate information regarding the experiences of families, especially adult siblings, of individuals with a mental illness. Specifically, there is a lack of research investigating individuals’ perceptions of their brother or sister’s mental illness as well as how this affects the sibling relationship. It is for this reason that the current study aimed at exploring the lived experiences of ‘black1’ isiXhosa speaking individuals who have a sibling with a mental illness. The study employed Interpretative Phenomenological Analysis (IPA) as its qualitative approach. A sample of five participants between the ages of 20-50 years was selected through purposive and snowballing sampling techniques. Semi-structured interviews were utilised and were transcribed and analysed based on the IPA framework. The analysis of the participants’ transcripts provided three master themes, which are supported by subordinate themes. The master themes are: 1) experiencing the sibling as a burden post diagnosis, 2) positive experiences from the sibling’s mental illness, 3) participant’s experiences of their sibling’s treatment and the mental health care system. Participants experienced financial burden as well as the burden of caregiving as a result of their sibling’s mental illness; these are understood as being subjective and objective burdens. While no change was experienced within the sibling relationship, the siblings’ mental illness was experienced as affecting the sibling relationship due to the socioeconomic status of the participants and stigma. The findings support and expand on the growing knowledge of adult sibling relationships and mental illness.
- Full Text:
- Date Issued: 2017
The effects of a lion (Panthera Leo) re-introduction on a resident cheetah (Acinonyx Jubatus) population In Mountain Zebra National Park, Eastern Cape, South Africa
- Authors: Van de Vyver, Daniel
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7420 , vital:21259
- Description: The global decline of large (> 10 kg) carnivores has resulted in a variety of conservation measures being put into practice to prevent extinctions. The establishment of predator-proof fences around protected areas has been a successful tool for reducing human-predator conflict. Furthermore, the re-introduction of large carnivores into small (< 1 000 km²), enclosed reserves has aided in the conservation of many species. Cheetahs (Acinonyx jubatus) and lions (Panthera leo) have benefitted from such re-introductions. The re-introduction of cheetahs before lions into the Mountain Zebra National Park (MZNP) in the Eastern Cape Province of South Africa provided a unique opportunity to study the effects of lions on an already established cheetah population. Spatial data were downloaded remotely from GPS collared individuals (n=4) and cheetah kill data were collected using the GPS cluster method before (2012-2013) and after (2013-2014) the lion (n=3) re-introduction. The same methods were used for lion kill data collection once they had been re-introduced. In general, cheetah home range size did not change after the lion re-introduction. Cheetahs selected areas with a combination of open and closed vegetation covers, while lions selected either open or closed areas of vegetation covers. In addition, as vegetation cover became thicker, the presence of cheetahs decreased. The cheetahs preyed upon seven species before and 11 species after the lion re-introduction. Medium sized prey comprised the bulk of the cheetah diet with kudu (Tragelaphus strepsiceros) and springbok (Antidorcas marsupialis) being the preferred species both before and after the lion re-introduction. The lion diets consisted of medium to large sized prey, with the male lions selecting eland (Tragelaphus oryx) and buffalo (Syncerus caffer) and the lioness selecting red hartebeest (Alcelaphus buselaphus). The cheetahs had no significant dietary overlap with the lions and there was only one record of kleptoparasitism. The results of my study indicate that cheetahs are able to co-exist with lions when lions are at low densities in an enclosed reserve. The cheetahs did not experience landscape-level displacement because they made fine-scale adjustments to avoid lions within their environment. This adaptability may have important management implications for future re-introductions of cheetahs into enclosed game reserves.
- Full Text:
- Date Issued: 2017
- Authors: Van de Vyver, Daniel
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7420 , vital:21259
- Description: The global decline of large (> 10 kg) carnivores has resulted in a variety of conservation measures being put into practice to prevent extinctions. The establishment of predator-proof fences around protected areas has been a successful tool for reducing human-predator conflict. Furthermore, the re-introduction of large carnivores into small (< 1 000 km²), enclosed reserves has aided in the conservation of many species. Cheetahs (Acinonyx jubatus) and lions (Panthera leo) have benefitted from such re-introductions. The re-introduction of cheetahs before lions into the Mountain Zebra National Park (MZNP) in the Eastern Cape Province of South Africa provided a unique opportunity to study the effects of lions on an already established cheetah population. Spatial data were downloaded remotely from GPS collared individuals (n=4) and cheetah kill data were collected using the GPS cluster method before (2012-2013) and after (2013-2014) the lion (n=3) re-introduction. The same methods were used for lion kill data collection once they had been re-introduced. In general, cheetah home range size did not change after the lion re-introduction. Cheetahs selected areas with a combination of open and closed vegetation covers, while lions selected either open or closed areas of vegetation covers. In addition, as vegetation cover became thicker, the presence of cheetahs decreased. The cheetahs preyed upon seven species before and 11 species after the lion re-introduction. Medium sized prey comprised the bulk of the cheetah diet with kudu (Tragelaphus strepsiceros) and springbok (Antidorcas marsupialis) being the preferred species both before and after the lion re-introduction. The lion diets consisted of medium to large sized prey, with the male lions selecting eland (Tragelaphus oryx) and buffalo (Syncerus caffer) and the lioness selecting red hartebeest (Alcelaphus buselaphus). The cheetahs had no significant dietary overlap with the lions and there was only one record of kleptoparasitism. The results of my study indicate that cheetahs are able to co-exist with lions when lions are at low densities in an enclosed reserve. The cheetahs did not experience landscape-level displacement because they made fine-scale adjustments to avoid lions within their environment. This adaptability may have important management implications for future re-introductions of cheetahs into enclosed game reserves.
- Full Text:
- Date Issued: 2017
Investigating the use of models to develop Grade 8 learners’ conceptual understanding of and procedural fluency with fractions
- Authors: Albin, Simon
- Date: 2017
- Subjects: Fractions -- Study and teaching (Secondary) -- Namibia , Mathematics -- Study and teaching (Secondary) -- Namibia , Information visualization , Visual learning -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/36288 , vital:24537
- Description: Both my teaching experience and literature of this research study strongly suggested that fractions are difficult to teach and learn across the globe generally, and Namibia in particular. One of the identified contributing factors was teaching fractions by focusing on procedures and not the conceptual understanding. Therefore, this research project developed and implemented an intervention in order to experiment and suggest an alternative teaching approach of fractions using models. The purpose of this research was to: “Investigate the use of models to develop Grade 8 learners’ conceptual understanding of and procedural fluency with fractions”. This investigation had three areas of focus. Firstly, the study investigated the nature of learners’ conceptual understanding of and procedural fluency with fractions before the teaching intervention, by means of administering a pre-test and pre-interview and analysing learners’ responses. Secondly, the study investigated the changes in learners’ conceptual understanding of and procedural fluency with fractions after the teaching intervention, by means of administering a post-test, post-interviews and recall interviews, and analysing learners’ responses. Thirdly, this study investigated the possible influence of the teaching intervention on the changes in learners’ conceptual understanding of and procedural fluency with fractions by analysing the lesson videos and learners’ worksheets, and describe their critical interaction. This study was conducted at a multicultural urban secondary school located in the Oshikoto Region, Namibia. The sample consisted of 12 Grade 8 mathematics learners whose age ranged from 13-16 years old. A purposive sampling method was employed to select both the research site and participants. This research is framed as a case study, and is grounded within the interpretive paradigm and qualitative research. This research revealed that these learners displayed conceptual and procedural difficulties in their engagement with fraction models and fraction symbols, before the teaching intervention. Conceptually, the study found that these learners read fractions using inappropriate names; and learners did not identify the whole unit in the models and therefore identified fractions represented by the fraction models using different forms of inappropriate fraction symbols. Procedurally, the study found that these learners compared and ordered fractions inappropriately using the sizes of the numerators and denominators separately; and learners used the lowest common denominator method inappropriately for adding fractions with different denominators. The research also suggested conceptual and procedural changes in learners’ conceptual understanding of and procedural fluency with fractions and that the intervention seemed to help learners to engage better with fraction models and fraction symbols. Conceptually, the findings suggested that the intervention using area models and number lines, seemed to help these learners to read fractions using appropriate names; to identify the whole unit in the fraction models and to develop a sense of the size of fractions in relation to one whole unit. Procedurally, the learners compared and ordered fractions appropriately using either equal fraction bars, equal number lines, benchmarking or rules for comparing and ordering fractions with the same numerator or denominator; and learners used equal fraction bars to visually represent the lowest common denominator method and to recognise that only equally sized units can be counted together. This research identified four factors as possible influences of the teaching intervention. These factors are namely: identifying both fraction symbols and appropriate fraction names to see fractions as relational numbers; prompting to partition whole units of the fraction models and graphically illustrating fraction symbols to identify the whole unit in the fraction models and to develop a sense of the size of fractions in relation to one whole unit; graphically illustrating fraction symbols using the models to use equal fraction bars and number lines, benchmarking and rules for comparing; and graphically illustrating fraction denominations using equal fraction bars to recognise that only equally sized units can be counted together. This research strongly suggests that the effective use of models has the potential to develop learners’ conceptual understanding of and procedural fluency with fractions in a number of ways.
- Full Text:
- Date Issued: 2017
- Authors: Albin, Simon
- Date: 2017
- Subjects: Fractions -- Study and teaching (Secondary) -- Namibia , Mathematics -- Study and teaching (Secondary) -- Namibia , Information visualization , Visual learning -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/36288 , vital:24537
- Description: Both my teaching experience and literature of this research study strongly suggested that fractions are difficult to teach and learn across the globe generally, and Namibia in particular. One of the identified contributing factors was teaching fractions by focusing on procedures and not the conceptual understanding. Therefore, this research project developed and implemented an intervention in order to experiment and suggest an alternative teaching approach of fractions using models. The purpose of this research was to: “Investigate the use of models to develop Grade 8 learners’ conceptual understanding of and procedural fluency with fractions”. This investigation had three areas of focus. Firstly, the study investigated the nature of learners’ conceptual understanding of and procedural fluency with fractions before the teaching intervention, by means of administering a pre-test and pre-interview and analysing learners’ responses. Secondly, the study investigated the changes in learners’ conceptual understanding of and procedural fluency with fractions after the teaching intervention, by means of administering a post-test, post-interviews and recall interviews, and analysing learners’ responses. Thirdly, this study investigated the possible influence of the teaching intervention on the changes in learners’ conceptual understanding of and procedural fluency with fractions by analysing the lesson videos and learners’ worksheets, and describe their critical interaction. This study was conducted at a multicultural urban secondary school located in the Oshikoto Region, Namibia. The sample consisted of 12 Grade 8 mathematics learners whose age ranged from 13-16 years old. A purposive sampling method was employed to select both the research site and participants. This research is framed as a case study, and is grounded within the interpretive paradigm and qualitative research. This research revealed that these learners displayed conceptual and procedural difficulties in their engagement with fraction models and fraction symbols, before the teaching intervention. Conceptually, the study found that these learners read fractions using inappropriate names; and learners did not identify the whole unit in the models and therefore identified fractions represented by the fraction models using different forms of inappropriate fraction symbols. Procedurally, the study found that these learners compared and ordered fractions inappropriately using the sizes of the numerators and denominators separately; and learners used the lowest common denominator method inappropriately for adding fractions with different denominators. The research also suggested conceptual and procedural changes in learners’ conceptual understanding of and procedural fluency with fractions and that the intervention seemed to help learners to engage better with fraction models and fraction symbols. Conceptually, the findings suggested that the intervention using area models and number lines, seemed to help these learners to read fractions using appropriate names; to identify the whole unit in the fraction models and to develop a sense of the size of fractions in relation to one whole unit. Procedurally, the learners compared and ordered fractions appropriately using either equal fraction bars, equal number lines, benchmarking or rules for comparing and ordering fractions with the same numerator or denominator; and learners used equal fraction bars to visually represent the lowest common denominator method and to recognise that only equally sized units can be counted together. This research identified four factors as possible influences of the teaching intervention. These factors are namely: identifying both fraction symbols and appropriate fraction names to see fractions as relational numbers; prompting to partition whole units of the fraction models and graphically illustrating fraction symbols to identify the whole unit in the fraction models and to develop a sense of the size of fractions in relation to one whole unit; graphically illustrating fraction symbols using the models to use equal fraction bars and number lines, benchmarking and rules for comparing; and graphically illustrating fraction denominations using equal fraction bars to recognise that only equally sized units can be counted together. This research strongly suggests that the effective use of models has the potential to develop learners’ conceptual understanding of and procedural fluency with fractions in a number of ways.
- Full Text:
- Date Issued: 2017
The effect of carbohydrate on dusky kob, Argyrosomus japonicus, fed pelleted diets
- Authors: Mabasa, Nyiko Charity
- Date: 2017
- Subjects: Carbohydrates in animal nutrition , Fishes -- Feeding and feeds , Argyrosomus japonicus , Argyrosomus , Argyrosomus japonicus -- Nutrition , Argyrosomus -- Nutrition , Argyrosomus japonicus -- Feeding and feeds , Argyrosomus -- Feeding and feeds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/44895 , vital:25450
- Description: The dusky kob, Argyrosomus japonicus, is an emerging commercial marine aquaculture species in South Africa. Attributes such as market acceptance, fast growth rates, tolerance to sibling density, acceptance of pelleted feed and adaptability to intensive aquaculture conditions make it a good candidate. Feed, the largest running cost in most aquaculture operations, is a limiting factor in dusky kob production as its nutritional requirements are not well understood. The present project formed part of a research program to develop a locally produced, least cost and sustainable feed that will support the growth and health of dusky kob. The approximate protein and energy requirements for kob fed formulated feeds have been established in earlier research, but the ability of kob to utilize carbohydrates as an energy source has not previously been investigated. The aim of this study was to determine the efficiency of dusky kob to utilize graded levels of carbohydrate (pregelatinized maize starch - PGMS) in pelleted diets. The research objectives were to determine the effect of dietary carbohydrate levels on:i) growth and feed utilization; ii) post prandial blood glucose levels; and iii) general fish health, gut bacterial composition and liver glycogen content of juvenile dusky kob. Hatchery reared juvenile dusky kob (5 g) were acclimatized in a recirculating experimental aquaculture system at the Department of Ichthyology and Fisheries Science at Rhodes University. They were fed trout crumble starter feed for three weeks before the start of the feeding experiment. Five diets containing 4.1, 8.2, 16.4 and 24.6% carbohydrate, hereafter referred to as 4.1C, 8.2C, 16.4C and 24.6C respectively, were formulated with pregelatinized maize starch as a carbohydrate source and fishmeal as the main protein source. Fish were fed these diets twice daily at 3.85% body weight per day for three months. Specific growth rates and feed conversion rations differed significantly between the four dietary treatments. Growth rate increased with increasing carbohydrate up to 16.4%, after which a significant decline was observed. Diet 16.4C produced the highest specific growth rate (SGR) of 1.84 ± 0.05% body weight/day, and the lowest feed conversion ratio of 1.28 ± 0.08. While the lowest specific growth rate and highest feed conversion ratio of 0.79 ± 0.05 and 2.14 ± 0.13 respectively, were found for diet 24.6C. A third order polynomial regression, using SGR, determined the optimum carbohydrate inclusion for dusky kob to be 16.72%. The general structure of the liver was similar between all fish fed the dietary treatments and all fish liver samples displayed a certain degree of lipid vacuolization of the hepatocytes. Evidence of starvation was observed in the livers of fish fed diet 24.6C. However, no differences in the amount of liver glycogen were observed. Gut bacterial composition did not differ among the different diets or between the different sections of the gut. Differences were however observed in the diversity of the bacterial community structure at the start (when they were fed commercial trout feed) and end of the experimental period (after being fed a fishmeal-maize diet). The rate at which glucose was cleared from the blood differed significantly between diets. The low carbohydrate diets (i.e. diet 4.1C and 8.2C) showed a steady rate of glucose removal from the blood over a 48 h experimental period. Sharp increases in blood glucose concentration were observed in diet 16.4C and diet 24.6C, with highest glucose concentrations of 7.18 ± 1.81 and 8.05 ± 2.35 mmol/l respectively, observed 24 h after feeding. The blood glucose concentration of the fish fed diet 16.4C however returned to resting glucose concentration after 48 h, while that of the fish fed diet 24.6C did not. The results demonstrated that the level of dietary carbohydrate inclusion has a significant effect on the growth and health of the fish. The optimum carbohydrate inclusion in dusky kob diets is indicated to be 16.7%, which gave the best growth rate and maximum protein sparing effect without adverse effects on fish health. These findings are important for diet formulation and producing ‘least-cost’ diets for dusky kob farming.
- Full Text:
- Date Issued: 2017
- Authors: Mabasa, Nyiko Charity
- Date: 2017
- Subjects: Carbohydrates in animal nutrition , Fishes -- Feeding and feeds , Argyrosomus japonicus , Argyrosomus , Argyrosomus japonicus -- Nutrition , Argyrosomus -- Nutrition , Argyrosomus japonicus -- Feeding and feeds , Argyrosomus -- Feeding and feeds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/44895 , vital:25450
- Description: The dusky kob, Argyrosomus japonicus, is an emerging commercial marine aquaculture species in South Africa. Attributes such as market acceptance, fast growth rates, tolerance to sibling density, acceptance of pelleted feed and adaptability to intensive aquaculture conditions make it a good candidate. Feed, the largest running cost in most aquaculture operations, is a limiting factor in dusky kob production as its nutritional requirements are not well understood. The present project formed part of a research program to develop a locally produced, least cost and sustainable feed that will support the growth and health of dusky kob. The approximate protein and energy requirements for kob fed formulated feeds have been established in earlier research, but the ability of kob to utilize carbohydrates as an energy source has not previously been investigated. The aim of this study was to determine the efficiency of dusky kob to utilize graded levels of carbohydrate (pregelatinized maize starch - PGMS) in pelleted diets. The research objectives were to determine the effect of dietary carbohydrate levels on:i) growth and feed utilization; ii) post prandial blood glucose levels; and iii) general fish health, gut bacterial composition and liver glycogen content of juvenile dusky kob. Hatchery reared juvenile dusky kob (5 g) were acclimatized in a recirculating experimental aquaculture system at the Department of Ichthyology and Fisheries Science at Rhodes University. They were fed trout crumble starter feed for three weeks before the start of the feeding experiment. Five diets containing 4.1, 8.2, 16.4 and 24.6% carbohydrate, hereafter referred to as 4.1C, 8.2C, 16.4C and 24.6C respectively, were formulated with pregelatinized maize starch as a carbohydrate source and fishmeal as the main protein source. Fish were fed these diets twice daily at 3.85% body weight per day for three months. Specific growth rates and feed conversion rations differed significantly between the four dietary treatments. Growth rate increased with increasing carbohydrate up to 16.4%, after which a significant decline was observed. Diet 16.4C produced the highest specific growth rate (SGR) of 1.84 ± 0.05% body weight/day, and the lowest feed conversion ratio of 1.28 ± 0.08. While the lowest specific growth rate and highest feed conversion ratio of 0.79 ± 0.05 and 2.14 ± 0.13 respectively, were found for diet 24.6C. A third order polynomial regression, using SGR, determined the optimum carbohydrate inclusion for dusky kob to be 16.72%. The general structure of the liver was similar between all fish fed the dietary treatments and all fish liver samples displayed a certain degree of lipid vacuolization of the hepatocytes. Evidence of starvation was observed in the livers of fish fed diet 24.6C. However, no differences in the amount of liver glycogen were observed. Gut bacterial composition did not differ among the different diets or between the different sections of the gut. Differences were however observed in the diversity of the bacterial community structure at the start (when they were fed commercial trout feed) and end of the experimental period (after being fed a fishmeal-maize diet). The rate at which glucose was cleared from the blood differed significantly between diets. The low carbohydrate diets (i.e. diet 4.1C and 8.2C) showed a steady rate of glucose removal from the blood over a 48 h experimental period. Sharp increases in blood glucose concentration were observed in diet 16.4C and diet 24.6C, with highest glucose concentrations of 7.18 ± 1.81 and 8.05 ± 2.35 mmol/l respectively, observed 24 h after feeding. The blood glucose concentration of the fish fed diet 16.4C however returned to resting glucose concentration after 48 h, while that of the fish fed diet 24.6C did not. The results demonstrated that the level of dietary carbohydrate inclusion has a significant effect on the growth and health of the fish. The optimum carbohydrate inclusion in dusky kob diets is indicated to be 16.7%, which gave the best growth rate and maximum protein sparing effect without adverse effects on fish health. These findings are important for diet formulation and producing ‘least-cost’ diets for dusky kob farming.
- Full Text:
- Date Issued: 2017
Analysis of a foundational biomedical curriculum: exploring cumulative knowledge-building in the rehabilitative health professions
- Authors: De Bie, Gabrielle
- Date: 2017
- Subjects: Medical education -- Curricula , Human anatomy -- Study and teaching -- Curricula , Physiology -- Study and teaching -- Curricula , Occupational therapy -- Study and teaching -- Curricula , Physical therapy -- Study and teaching -- Curricula , Medical rehabilitation -- Study and teaching -- Curricula , Knowledge, Theory of
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/18617 , vital:22361
- Description: This study was motivated by the researcher's experience that students in the rehabilitative health professional programmes were finding it difficult to access fundamental knowledge upon which their professional practices and clinical contexts are based. An important focus of the research was the extent to which cumulative knowledge-building was impacted after the foundational biomedical curriculum became an interdisciplinary programme. The study explored whether the organisation of the interdisciplinary foundational curriculum served the fundamental needs of the professions, and whether, as a matter of social justice, students' access to powerful knowledge was enabled by the form that the fundamental curriculum assumed. This curriculum study at a particular Faculty of Health Sciences foregrounds the structuring, organisation and differentiation of disciplinary knowledge, and reflects a twenty year period that included not only transitions in professional education but also extensive transformation in, and a different approach to, health delivery. At the institution, physiology and anatomy, the biomedical sciences basic to the health professions, underwent disciplinary merging and subsequent altered positioning in curricula. Medicine opted for a problem-based learning approach whereas the rehabilitation health sciences did not. Legitimation Code Theory (LCT) provided the means for analysis of the extent to which interdisciplinary organisation in the foundational curriculum for Physiotherapy and Occupational Therapy enabled integrative, cumulative building of knowledge for professional and clinical contexts. Specialisation and Semantics dimensions of Legitimation Code Theory were used to reveal the principles underpinning practices, contexts and dispositions of Anatomy and Physiology at the Faculty of Health Sciences over a twenty year period post democratisation in South Africa (1994 - 2013). Disciplinary positioning in curriculum prior- and post-merger, were compared and contrasted. LCT were used to characterise the distinctiveness of Physiotherapy and Occupational Therapy at the university including the kind of knowledge and the kind of knower that specialises the different professions, and what is valorised and legitimated for each kind of professional. Semantic gravity was used to explore the expected knowledge recontextualisations in diverse and complex clinical settings for each of the professions. Registered professionals who are clinical educators as well as curriculum designers for clinical studies were interviewed. Profession-specific course outlines were further data sources. The biomedical disciplines Anatomy and Physiology were characterised for their measures of distinction and their respective knowledge-knower structures. Analysis traced each discipline from its strongly classified form in autonomous curricula when there were separate learner-cohorts for physiotherapists and occupational therapists, to post-merger when the disciplines were framed as human biology in an integrated foundational curriculum for a joint cohort of students. Curricular documents for the twenty year period were analysed quantitatively and qualitatively to establish the positioning of Physiology and Anatomy before and after the disciplines merged to a single course of Human Biology. Teaching staff were interviewed for their understanding of what specialises the physiological and anatomical components of the Human Biology curriculum, what they considered as powerful knowledge for the professions, and who they envisaged as the ideal student-knower exiting the basic sciences platform to enter more advanced clinical studies. The degree of context-dependence for meaning-making in the different disciplinary domains and the condensation of meanings inherent in the respective practices and contexts, were analysed. The thesis argues that following the merger Anatomy is preferentially legitimated as powerful knowledge at the expense of Physiology; that the ideal of disciplinary integration is not reached, and that the segmental organisation and structuring of the curriculum negatively impacted on cumulative knowledge-building and application of professional knowledge in the clinical arena. After the merger the disciplines lost their shape, and in particular the hierarchical knowledge structure of Physiology collapsed. By not having access to the necessary disciplinary knowledge structures and their associated practices, students' ability for scaffolding and integrating knowledge into the clinical arena was constrained. The organisation of the current Human Biology curriculum does not facilitate cumulative learning, and in so doing may not contribute to the envisaged graduate professional who is required to practice within a complex and demanding healthcare work environment. The significance of this study conveys that interdisciplinary programmes should be carefully considered, and there is an added imperative in the health professions which ultimately realise treatment of patients. If, aside from interdisciplinary teaching, there are also merged cohorts of participant students, then a sound understanding of the epistemic requirements of each profession is required. Those involved in curriculum development in various fields need to take these recommendations into account to enable cumulative learning and enable epistemological access to powerful knowledge for an increasingly diverse student body.
- Full Text:
- Date Issued: 2017
- Authors: De Bie, Gabrielle
- Date: 2017
- Subjects: Medical education -- Curricula , Human anatomy -- Study and teaching -- Curricula , Physiology -- Study and teaching -- Curricula , Occupational therapy -- Study and teaching -- Curricula , Physical therapy -- Study and teaching -- Curricula , Medical rehabilitation -- Study and teaching -- Curricula , Knowledge, Theory of
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/18617 , vital:22361
- Description: This study was motivated by the researcher's experience that students in the rehabilitative health professional programmes were finding it difficult to access fundamental knowledge upon which their professional practices and clinical contexts are based. An important focus of the research was the extent to which cumulative knowledge-building was impacted after the foundational biomedical curriculum became an interdisciplinary programme. The study explored whether the organisation of the interdisciplinary foundational curriculum served the fundamental needs of the professions, and whether, as a matter of social justice, students' access to powerful knowledge was enabled by the form that the fundamental curriculum assumed. This curriculum study at a particular Faculty of Health Sciences foregrounds the structuring, organisation and differentiation of disciplinary knowledge, and reflects a twenty year period that included not only transitions in professional education but also extensive transformation in, and a different approach to, health delivery. At the institution, physiology and anatomy, the biomedical sciences basic to the health professions, underwent disciplinary merging and subsequent altered positioning in curricula. Medicine opted for a problem-based learning approach whereas the rehabilitation health sciences did not. Legitimation Code Theory (LCT) provided the means for analysis of the extent to which interdisciplinary organisation in the foundational curriculum for Physiotherapy and Occupational Therapy enabled integrative, cumulative building of knowledge for professional and clinical contexts. Specialisation and Semantics dimensions of Legitimation Code Theory were used to reveal the principles underpinning practices, contexts and dispositions of Anatomy and Physiology at the Faculty of Health Sciences over a twenty year period post democratisation in South Africa (1994 - 2013). Disciplinary positioning in curriculum prior- and post-merger, were compared and contrasted. LCT were used to characterise the distinctiveness of Physiotherapy and Occupational Therapy at the university including the kind of knowledge and the kind of knower that specialises the different professions, and what is valorised and legitimated for each kind of professional. Semantic gravity was used to explore the expected knowledge recontextualisations in diverse and complex clinical settings for each of the professions. Registered professionals who are clinical educators as well as curriculum designers for clinical studies were interviewed. Profession-specific course outlines were further data sources. The biomedical disciplines Anatomy and Physiology were characterised for their measures of distinction and their respective knowledge-knower structures. Analysis traced each discipline from its strongly classified form in autonomous curricula when there were separate learner-cohorts for physiotherapists and occupational therapists, to post-merger when the disciplines were framed as human biology in an integrated foundational curriculum for a joint cohort of students. Curricular documents for the twenty year period were analysed quantitatively and qualitatively to establish the positioning of Physiology and Anatomy before and after the disciplines merged to a single course of Human Biology. Teaching staff were interviewed for their understanding of what specialises the physiological and anatomical components of the Human Biology curriculum, what they considered as powerful knowledge for the professions, and who they envisaged as the ideal student-knower exiting the basic sciences platform to enter more advanced clinical studies. The degree of context-dependence for meaning-making in the different disciplinary domains and the condensation of meanings inherent in the respective practices and contexts, were analysed. The thesis argues that following the merger Anatomy is preferentially legitimated as powerful knowledge at the expense of Physiology; that the ideal of disciplinary integration is not reached, and that the segmental organisation and structuring of the curriculum negatively impacted on cumulative knowledge-building and application of professional knowledge in the clinical arena. After the merger the disciplines lost their shape, and in particular the hierarchical knowledge structure of Physiology collapsed. By not having access to the necessary disciplinary knowledge structures and their associated practices, students' ability for scaffolding and integrating knowledge into the clinical arena was constrained. The organisation of the current Human Biology curriculum does not facilitate cumulative learning, and in so doing may not contribute to the envisaged graduate professional who is required to practice within a complex and demanding healthcare work environment. The significance of this study conveys that interdisciplinary programmes should be carefully considered, and there is an added imperative in the health professions which ultimately realise treatment of patients. If, aside from interdisciplinary teaching, there are also merged cohorts of participant students, then a sound understanding of the epistemic requirements of each profession is required. Those involved in curriculum development in various fields need to take these recommendations into account to enable cumulative learning and enable epistemological access to powerful knowledge for an increasingly diverse student body.
- Full Text:
- Date Issued: 2017
The role of protected areas in the conservation and management of fisheries in the Chobe District of Botswana
- Authors: Bakane, Modiegi
- Date: 2017
- Subjects: Cichlids Botswana Chobe District , Protected areas Botswana Chobe District , Fishery management Botswana Chobe District
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7459 , vital:21262
- Description: This study was aimed at better understanding the function of protected areas as a management strategy for the Chobe District fishery in Botswana, by first investigating the relative abundance in fish communities in and outside protected areas and secondly, by performing an assessment of the biology of commercially important large cichlid species viz threespot tilapia Oreochromis andersonii, greenhead tilapia Oreochromis macrochir and redbreast tilapia Coptodon rendalli. In this study, data and specimens were collected during seasonal surveys between September 2014 and April 2015, using the standard graded fleets of gillnets employed in other programmes in the region, together with D-nets, angling and electro-fishing. The study demonstrated that fish communities in the floodplain ecosystems in the Chobe District of Botswana were representative of the region, containing some 70 species in 14 families. This study also demonstrated that for all the species collected, the mean Catch Per Unit Effort (CPUE) by weight for all the species was significantly higher in protected areas (Kruskal Wallis Test; P<0.05) namely, Zibadianja Lagoon (38 ± 31 kg/net.night"1 and Savuti River/marsh 25 ± 19 kg/net.night"1) than in the fished Chobe River floodplains CPUE (6 ± 3 kg/net.night-1). Biological contributions were estimates of longevity, growth and maturity for O. andersonii, O. macrochir and C. rendalli. Age and growth were estimated using sectioned sagittal otoliths. The Von Bertalanffy growth equation from otolith derived length at age was Lt(mm) =298 (1-e-0 59(t=- 098)) for O. andersonii and Lt(mm) = 337 (1-e-0'20(t=-235)) for C. rendalli. The results indicated that protected areas enhanced fish longevity, and fish in protected areas were larger and older than those in exploited areas. Maturity estimates for the large cichlids were consistent with other research in the region and the length-at-50% maturity was estimated as 250mm Lt for O. andersonii, 225 mm Lt for O. macrochir and 210 mm Lt for C. rendalli. Management recommendations are therefore to retain gill net mesh size regulations that ensure that these fish reach maturity and can breed before being harvested and to assess the possibility of increasing the number of protected areas in the district.
- Full Text:
- Date Issued: 2017
- Authors: Bakane, Modiegi
- Date: 2017
- Subjects: Cichlids Botswana Chobe District , Protected areas Botswana Chobe District , Fishery management Botswana Chobe District
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7459 , vital:21262
- Description: This study was aimed at better understanding the function of protected areas as a management strategy for the Chobe District fishery in Botswana, by first investigating the relative abundance in fish communities in and outside protected areas and secondly, by performing an assessment of the biology of commercially important large cichlid species viz threespot tilapia Oreochromis andersonii, greenhead tilapia Oreochromis macrochir and redbreast tilapia Coptodon rendalli. In this study, data and specimens were collected during seasonal surveys between September 2014 and April 2015, using the standard graded fleets of gillnets employed in other programmes in the region, together with D-nets, angling and electro-fishing. The study demonstrated that fish communities in the floodplain ecosystems in the Chobe District of Botswana were representative of the region, containing some 70 species in 14 families. This study also demonstrated that for all the species collected, the mean Catch Per Unit Effort (CPUE) by weight for all the species was significantly higher in protected areas (Kruskal Wallis Test; P<0.05) namely, Zibadianja Lagoon (38 ± 31 kg/net.night"1 and Savuti River/marsh 25 ± 19 kg/net.night"1) than in the fished Chobe River floodplains CPUE (6 ± 3 kg/net.night-1). Biological contributions were estimates of longevity, growth and maturity for O. andersonii, O. macrochir and C. rendalli. Age and growth were estimated using sectioned sagittal otoliths. The Von Bertalanffy growth equation from otolith derived length at age was Lt(mm) =298 (1-e-0 59(t=- 098)) for O. andersonii and Lt(mm) = 337 (1-e-0'20(t=-235)) for C. rendalli. The results indicated that protected areas enhanced fish longevity, and fish in protected areas were larger and older than those in exploited areas. Maturity estimates for the large cichlids were consistent with other research in the region and the length-at-50% maturity was estimated as 250mm Lt for O. andersonii, 225 mm Lt for O. macrochir and 210 mm Lt for C. rendalli. Management recommendations are therefore to retain gill net mesh size regulations that ensure that these fish reach maturity and can breed before being harvested and to assess the possibility of increasing the number of protected areas in the district.
- Full Text:
- Date Issued: 2017
Development and assessment of gastric-retentive sustained release metronidazole microcapsules
- Authors: Makan, Anjana
- Date: 2017
- Subjects: Metronidazole , Drug delivery systems , Helicobacter pylori , High performance liquid chromatography , Gas chromatography , Drugs , Drugs Controlled release
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/59240 , vital:27491
- Description: Helicobacter pylori is one of the most common pathogenic bacterial infections and is the leading cause of gastritis, gastroduodenal ulcer disease and gastric cancers. Studies have revealed the prevalence of Helicobacter pylori is high in many countries around the globe. Although Helicobacter pylori is highly sensitive to antimicrobial agents in vitro the clinical eradication rate of the disease is still low. The instability of API at gastric pH, low concentration of API in the gastric mucosa and short gastric residence times are the main reasons for poor eradication rates. The high prevalence rate of this disease necessitates the design and development of gastric-retentive site specific oral dosage forms for the optimized delivery of existing therapeutic molecules and may be an approach to improving the eradication rate of Helicobacter pylori. Metronidazole (MTZ) is a 5-nitroimidazole derivative that exhibits antibiotic and antiprotozoal activity. MTZ is used in combination with other compounds for the treatment of Helicobacter pylori in peptic ulcer disease. MTZ is a potential candidate for inclusion in a sustained release gastric-retentive delivery system that acts in the stomach and since it is unstable in the intestinal/colonic environment enhancing gastric residence time would be a therapeutic advantage. MTZ is a cost-effective therapy that exhibits good anti-microbial activity and has a favourable pharmacokinetic profile. A sustained release gastric-retentive formulation is therefore proposed as an approach to enhance the local delivery of MTZ and improve treatment outcomes for patients infected with Helicobacter pylori. A stability indicating Reversed-Phase High Performance Liquid Chromatography (RP- HPLC) method for the quantitation of MTZ in pharmaceutical dosage forms was developed and optimised using a Central Composite Design (CCD) approach. The RP-HPLC method was found to be linear, accurate, precise, sensitive, selective, and was applied to the analysis of MTZ in commercially available medicines. Preformulation studies were conducted as preparative work prior to manufacture gastric- retentive sustained release MTZ microcapsules. The experiments conducted were tailored for the development of sustained release MTZ microcapsules using a solvent evaporation method. The particle size and shape of the microcapsules was investigated using Scanning Electron Microscopy (SEM). MTZ- excipient compatibility studies were performed using Fourier Transform Infra-red Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD). The results revealed that no definite interaction between MTZ and intended excipients to be used for manufacture of MTZ formulations occurred. A solvent evaporation procedure was used for the manufacture of MTZ microcapsules. Preliminary formulations were manufactured using two different grades of Methocel® at various levels. In addition the impact of processing parameters on performance was also investigated. The formulations were assessed in terms of in vitro release, buoyancy, yield, encapsulation efficiency and microcapsule size. Formulation optimisation was undertaken using a CCD approach and numerical optimisation was used to predict an optimised formulation composition that would produce minimal initial MTZ release, maximum MTZ release at 12 hours and maximum buoyancy, encapsulation efficiency and yield. The kinetics of MTZ release from microcapsules was established by fitting in vitro release data to different mathematical models. Higuchi model and first-order model appeared to best fit the data as majority of the formulation batches had highest R2 values for these models. Short-term stability assessment of the optimised formulation was established by undertaking stability studies at 25°C/60% RH and 40°C/75%RH. No significant changes in any of the CQA were observed over 30 days of stability testing. A gas chromatographic (GC) method was developed and validated for the quantitation of residual acetone and n-hexane. The optimised formulation contained 213.60 ppm/g acetone and 25.23 ppm/g n-hexane which are well below the limits set for residual solvents. In conclusion, gastric-retentive sustained release MTZ microcapsules with potential for further development and optimisation have been successfully developed and assessed in these studies. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2017
- Full Text:
- Date Issued: 2017
- Authors: Makan, Anjana
- Date: 2017
- Subjects: Metronidazole , Drug delivery systems , Helicobacter pylori , High performance liquid chromatography , Gas chromatography , Drugs , Drugs Controlled release
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/59240 , vital:27491
- Description: Helicobacter pylori is one of the most common pathogenic bacterial infections and is the leading cause of gastritis, gastroduodenal ulcer disease and gastric cancers. Studies have revealed the prevalence of Helicobacter pylori is high in many countries around the globe. Although Helicobacter pylori is highly sensitive to antimicrobial agents in vitro the clinical eradication rate of the disease is still low. The instability of API at gastric pH, low concentration of API in the gastric mucosa and short gastric residence times are the main reasons for poor eradication rates. The high prevalence rate of this disease necessitates the design and development of gastric-retentive site specific oral dosage forms for the optimized delivery of existing therapeutic molecules and may be an approach to improving the eradication rate of Helicobacter pylori. Metronidazole (MTZ) is a 5-nitroimidazole derivative that exhibits antibiotic and antiprotozoal activity. MTZ is used in combination with other compounds for the treatment of Helicobacter pylori in peptic ulcer disease. MTZ is a potential candidate for inclusion in a sustained release gastric-retentive delivery system that acts in the stomach and since it is unstable in the intestinal/colonic environment enhancing gastric residence time would be a therapeutic advantage. MTZ is a cost-effective therapy that exhibits good anti-microbial activity and has a favourable pharmacokinetic profile. A sustained release gastric-retentive formulation is therefore proposed as an approach to enhance the local delivery of MTZ and improve treatment outcomes for patients infected with Helicobacter pylori. A stability indicating Reversed-Phase High Performance Liquid Chromatography (RP- HPLC) method for the quantitation of MTZ in pharmaceutical dosage forms was developed and optimised using a Central Composite Design (CCD) approach. The RP-HPLC method was found to be linear, accurate, precise, sensitive, selective, and was applied to the analysis of MTZ in commercially available medicines. Preformulation studies were conducted as preparative work prior to manufacture gastric- retentive sustained release MTZ microcapsules. The experiments conducted were tailored for the development of sustained release MTZ microcapsules using a solvent evaporation method. The particle size and shape of the microcapsules was investigated using Scanning Electron Microscopy (SEM). MTZ- excipient compatibility studies were performed using Fourier Transform Infra-red Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD). The results revealed that no definite interaction between MTZ and intended excipients to be used for manufacture of MTZ formulations occurred. A solvent evaporation procedure was used for the manufacture of MTZ microcapsules. Preliminary formulations were manufactured using two different grades of Methocel® at various levels. In addition the impact of processing parameters on performance was also investigated. The formulations were assessed in terms of in vitro release, buoyancy, yield, encapsulation efficiency and microcapsule size. Formulation optimisation was undertaken using a CCD approach and numerical optimisation was used to predict an optimised formulation composition that would produce minimal initial MTZ release, maximum MTZ release at 12 hours and maximum buoyancy, encapsulation efficiency and yield. The kinetics of MTZ release from microcapsules was established by fitting in vitro release data to different mathematical models. Higuchi model and first-order model appeared to best fit the data as majority of the formulation batches had highest R2 values for these models. Short-term stability assessment of the optimised formulation was established by undertaking stability studies at 25°C/60% RH and 40°C/75%RH. No significant changes in any of the CQA were observed over 30 days of stability testing. A gas chromatographic (GC) method was developed and validated for the quantitation of residual acetone and n-hexane. The optimised formulation contained 213.60 ppm/g acetone and 25.23 ppm/g n-hexane which are well below the limits set for residual solvents. In conclusion, gastric-retentive sustained release MTZ microcapsules with potential for further development and optimisation have been successfully developed and assessed in these studies. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2017
- Full Text:
- Date Issued: 2017
An investigation of a Systemic Functional Linguistic approach for teaching Energy to grade 7 Natural Science and Health Education Learners: a Namibian case study
- Authors: Silvanus, Secilia Tulikefo
- Date: 2017
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/8165 , vital:21361
- Description: Learners’ general poor performance in science is a concern in science education. The literature mentions pedagogic strategies such as the use of practical activities and inclusion of indigenous knowledge, which are now acknowledged in various science curricula. In addition, many science educators and researchers are exploring innovative pedagogical approaches which may possibly help learners understand science better in order to improve their performance in the subject. Learners’ poor performance in science and possible strategies for improving this, are also a concern in Namibia. The Namibian national examination results (MoE, 2010-2014) revealed that the topic of Energy is one of those in which learners perform poorly. Energy is an important scientific concept that is widely used in various disciplines and it is thus problematic when science learners struggle to make sense of the scientific description of energy and related concepts. This triggered my interest to conduct a study focusing on the topic of energy. The study involved functional recasting from Systemic Functional Linguistic theory, as an intervention during my teaching the topic of energy to English second language grade 7 Natural Science and Health Education learners. The influence of the approach was investigated through the lens of social constructivism. The interpretive paradigm was adopted in order to make meaning of the learners’ experiences, during and after the intervention. Data collection instruments such as pre and post test, stimulated recall interviews, observation and learners’ journals were used. A qualitative approach was used to analyze the data. The pretest and post test results showed that a noticeable shift had occurred in learners’ understanding - the functional recasting teaching approach positively influenced learners’ sense making of energy concepts. Sense-making of energy concepts was evident in learners’ demonstrating the ability to construct and deconstruct technicality, making comprehensible output, meaningful use of gestures, scientific reasoning and asking relevant questions. The results also revealed dialogic discourse and positive attitudes as factors enabling learners’ progress. The language of learning and teaching, and negative attitudes were found to be constraining factors for learners’ progress. Functional recasting might be useful to science teachers and science teacher training programs as the finding for this study revealed that it enabled learners to make sense of energy concepts using scientific English. When using functional recasting, science teachers should consider the constraining factors and possibly avoid or minimize the impact.
- Full Text:
- Date Issued: 2017
- Authors: Silvanus, Secilia Tulikefo
- Date: 2017
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/8165 , vital:21361
- Description: Learners’ general poor performance in science is a concern in science education. The literature mentions pedagogic strategies such as the use of practical activities and inclusion of indigenous knowledge, which are now acknowledged in various science curricula. In addition, many science educators and researchers are exploring innovative pedagogical approaches which may possibly help learners understand science better in order to improve their performance in the subject. Learners’ poor performance in science and possible strategies for improving this, are also a concern in Namibia. The Namibian national examination results (MoE, 2010-2014) revealed that the topic of Energy is one of those in which learners perform poorly. Energy is an important scientific concept that is widely used in various disciplines and it is thus problematic when science learners struggle to make sense of the scientific description of energy and related concepts. This triggered my interest to conduct a study focusing on the topic of energy. The study involved functional recasting from Systemic Functional Linguistic theory, as an intervention during my teaching the topic of energy to English second language grade 7 Natural Science and Health Education learners. The influence of the approach was investigated through the lens of social constructivism. The interpretive paradigm was adopted in order to make meaning of the learners’ experiences, during and after the intervention. Data collection instruments such as pre and post test, stimulated recall interviews, observation and learners’ journals were used. A qualitative approach was used to analyze the data. The pretest and post test results showed that a noticeable shift had occurred in learners’ understanding - the functional recasting teaching approach positively influenced learners’ sense making of energy concepts. Sense-making of energy concepts was evident in learners’ demonstrating the ability to construct and deconstruct technicality, making comprehensible output, meaningful use of gestures, scientific reasoning and asking relevant questions. The results also revealed dialogic discourse and positive attitudes as factors enabling learners’ progress. The language of learning and teaching, and negative attitudes were found to be constraining factors for learners’ progress. Functional recasting might be useful to science teachers and science teacher training programs as the finding for this study revealed that it enabled learners to make sense of energy concepts using scientific English. When using functional recasting, science teachers should consider the constraining factors and possibly avoid or minimize the impact.
- Full Text:
- Date Issued: 2017
The isolation and genetic characterisation of a novel alphabaculovirus for the microbial control of Cryptophlebia peltastica and closely related tortricid pests
- Authors: Marsberg, Tamryn
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/59292 , vital:27543
- Description: Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae) is an economically damaging pest of litchis and macadamias in South Africa. Cryptophlebia peltastica causes both pre- and post-harvest damage to litchis, reducing overall yields and thus classifying the pest as a phytosanitary risk. Various control methods have been implemented against C. peltastica in an integrated pest management programme. These control methods include chemical control, cultural control and biological control. However, these methods have not yet provided satisfactory control as of yet. As a result, an alternative control option needs to be identified and implemented into the IPM programme. An alternative method of control that has proved successful in other agricultural sectors and not yet implemented in the control of C. peltastica is that of microbial control, specifically the use of baculovirus biopesticides. This study aimed to isolate and characterise a novel baculovirus from a laboratory culture of C. peltastica that could be used as a commercially available baculovirus biopesticide. In order to isolate a baculovirus a laboratory culture of C. peltastica was successfully established at Rhodes University, Grahamstown, South Africa. This is the first time a laboratory culture of C. peltastica has been established. This allowed for various biological aspects of the pest to be determined, which included: length of the life cycle, fecundity and time to oviposition, egg and larval development and percentage hatch. The results obtained from these studies found that the biology of C. peltastica was similar to that of Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae). Once the laboratory culture had reached high densities, larvae showing symptoms of baculovirus infection were observed. Symptomatic larvae were collected and examined for the presence of a baculovirus. An alphabaculovirus (NPV) was successfully isolated and morphologically identified using purified OBs that were sectioned and observed by transmission electron microscopy. This was then confirmed by amplifying the polyhedrin gene region using degenerate primers. A BLAST analysis found a 93% similarity to a partial polyhedrin gene sequence to be that of Epinotia granitalis (Butler) (Lepidoptera: Tortricidae). The alphabaculovirus was then genetically characterised by generating restriction profiles and sequencing the whole genome. Due to the novelty of the virus, no comparison could be made. The biological activity of the alphabaculovirus was then tested against C. peltastica and two closely related Tortricidae pests: T. leucotreta and Cydiapomonella (Linnaeous) (Lepidoptera: Tortricidae). The alphabaculovirus was highly virulent against all three species. The lethal concentrations (LC50 and LC90) for the virus against C. peltastica was 8.19 x 103 and 3.33 x 105 OBs/ml. The LC50 and LC90 for T. leucotreta was 2.29 x 103 and 9.97 x 104 OBs/ml, respectively and C. pomonella had a LC50 of 1.43 x 103 OBs/ml and LC90 1.26 x 104 OBs/ml. The virus was particularly virulent against T. leucotreta and C. pomonella as compared to C. peltastica. The biological activity of the alphabaculovirus was also tested against CpGV resistant European C. pomonella. From the results it was observed that the virus had the ability to overcome the resistance in C. pomonella and could potentially be used in the resistance management of C. pomonella. With the successful biological activity results obtained from this study, preliminary investigation were made into the mass production of the alphabaculovirus using both the in vivo and in vitro production methods. For in vivo production both the homologous host (C. peltastica) and a heterologous host (T leucotreta) were investigated. Preliminary studies focused on determining the biological activity in fifth instars of both hosts. Fifth instar LC50 and LC90 values for C. peltastica were 3.43 x 103 and 1.11 x 107 OBs/ml and for T. leucotreta the LC50 and LC90 values were 2.53 x 103 and 8.82 x 106 OBs/ml, respectively. The average yield of virus produced in each species was also determined. Cryptophlebia peltastica had the highest viral yield of 5.37 x 1010 OBs/larva and 2.93 x 1010 OBs/larva for T. leucotreta. The results obtained, from the preliminary investigation concluded that the virus could be produced in vivo in both C. peltastica and T. leucotreta, however further research is required into the mass production in both hosts. The in vitro production of the virus was also considered and the susceptibility of the virus was tested against the C. pomonella cell line, Cp14R. After infection of the Cp14R cells with budded virus collected from fifth instar C. peltastica larvae, OBs could be observed after three days. Thus, the alphabaculovirus is susceptible to the Cp14R cell line, thus has the potential to be produced in vitro and further characterised. This study is the first to report of the identification and characterisation of a novel alphabaculovirus isolated from a laboratory reared culture of C. peltastica and the potential for it to be commercially developed into a bipoesticide and used against Tortricidae pests.
- Full Text:
- Date Issued: 2017
- Authors: Marsberg, Tamryn
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/59292 , vital:27543
- Description: Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae) is an economically damaging pest of litchis and macadamias in South Africa. Cryptophlebia peltastica causes both pre- and post-harvest damage to litchis, reducing overall yields and thus classifying the pest as a phytosanitary risk. Various control methods have been implemented against C. peltastica in an integrated pest management programme. These control methods include chemical control, cultural control and biological control. However, these methods have not yet provided satisfactory control as of yet. As a result, an alternative control option needs to be identified and implemented into the IPM programme. An alternative method of control that has proved successful in other agricultural sectors and not yet implemented in the control of C. peltastica is that of microbial control, specifically the use of baculovirus biopesticides. This study aimed to isolate and characterise a novel baculovirus from a laboratory culture of C. peltastica that could be used as a commercially available baculovirus biopesticide. In order to isolate a baculovirus a laboratory culture of C. peltastica was successfully established at Rhodes University, Grahamstown, South Africa. This is the first time a laboratory culture of C. peltastica has been established. This allowed for various biological aspects of the pest to be determined, which included: length of the life cycle, fecundity and time to oviposition, egg and larval development and percentage hatch. The results obtained from these studies found that the biology of C. peltastica was similar to that of Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae). Once the laboratory culture had reached high densities, larvae showing symptoms of baculovirus infection were observed. Symptomatic larvae were collected and examined for the presence of a baculovirus. An alphabaculovirus (NPV) was successfully isolated and morphologically identified using purified OBs that were sectioned and observed by transmission electron microscopy. This was then confirmed by amplifying the polyhedrin gene region using degenerate primers. A BLAST analysis found a 93% similarity to a partial polyhedrin gene sequence to be that of Epinotia granitalis (Butler) (Lepidoptera: Tortricidae). The alphabaculovirus was then genetically characterised by generating restriction profiles and sequencing the whole genome. Due to the novelty of the virus, no comparison could be made. The biological activity of the alphabaculovirus was then tested against C. peltastica and two closely related Tortricidae pests: T. leucotreta and Cydiapomonella (Linnaeous) (Lepidoptera: Tortricidae). The alphabaculovirus was highly virulent against all three species. The lethal concentrations (LC50 and LC90) for the virus against C. peltastica was 8.19 x 103 and 3.33 x 105 OBs/ml. The LC50 and LC90 for T. leucotreta was 2.29 x 103 and 9.97 x 104 OBs/ml, respectively and C. pomonella had a LC50 of 1.43 x 103 OBs/ml and LC90 1.26 x 104 OBs/ml. The virus was particularly virulent against T. leucotreta and C. pomonella as compared to C. peltastica. The biological activity of the alphabaculovirus was also tested against CpGV resistant European C. pomonella. From the results it was observed that the virus had the ability to overcome the resistance in C. pomonella and could potentially be used in the resistance management of C. pomonella. With the successful biological activity results obtained from this study, preliminary investigation were made into the mass production of the alphabaculovirus using both the in vivo and in vitro production methods. For in vivo production both the homologous host (C. peltastica) and a heterologous host (T leucotreta) were investigated. Preliminary studies focused on determining the biological activity in fifth instars of both hosts. Fifth instar LC50 and LC90 values for C. peltastica were 3.43 x 103 and 1.11 x 107 OBs/ml and for T. leucotreta the LC50 and LC90 values were 2.53 x 103 and 8.82 x 106 OBs/ml, respectively. The average yield of virus produced in each species was also determined. Cryptophlebia peltastica had the highest viral yield of 5.37 x 1010 OBs/larva and 2.93 x 1010 OBs/larva for T. leucotreta. The results obtained, from the preliminary investigation concluded that the virus could be produced in vivo in both C. peltastica and T. leucotreta, however further research is required into the mass production in both hosts. The in vitro production of the virus was also considered and the susceptibility of the virus was tested against the C. pomonella cell line, Cp14R. After infection of the Cp14R cells with budded virus collected from fifth instar C. peltastica larvae, OBs could be observed after three days. Thus, the alphabaculovirus is susceptible to the Cp14R cell line, thus has the potential to be produced in vitro and further characterised. This study is the first to report of the identification and characterisation of a novel alphabaculovirus isolated from a laboratory reared culture of C. peltastica and the potential for it to be commercially developed into a bipoesticide and used against Tortricidae pests.
- Full Text:
- Date Issued: 2017
The Role of HOP in Emerin-Mediated Nuclear Structure
- Authors: Kituyi, Sarah Naulikha
- Date: 2017
- Subjects: Heat shock proteins , Nuclear structure , Nuclear membranes , Cancer Treatment , Molecular chaperones , Cytoskeleton , Cytoplasm
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/59230 , vital:27485 , DOI 10.21504/10962/59230
- Description: A vital component of the integral nuclear membrane is emerin, a Lamin Emerin and Man1 (LEM) domain protein whose concentration determines the levels of partner proteins that together constitute the structure of the nuclear envelope. Deficiencies in any of these proteins causes the failure of the structure and assembly and disassembly of the nuclear envelope, which disrupts chromosome segregation and nuclear compartmentalization that are both associated with disease. Emerin also localizes in the cytoplasm where it is implicated in the structure of the cytoskeleton via interaction with tubulin and actin and thus its deficiency may equally contribute to the collapse of the cytoskeleton. The Hsp70-Hsp90 organising protein (Hop) functions as a cochaperone for entry of client proteins into the Hsp90 folding cycle. Hop is upregulated in cancer and regulates a number of cell biology processes via interactions with proteins independently of Hsp90. In a previous study using global whole cell mass spectrometry, emerin was shown to be the most significantly down regulated protein in Hop depleted cell lysates. In this current study, it was postulated that emerin interacts with Hop, and this interaction regulates the stability, and level of emerin in the nucleus which impacts on the structure of the nuclear envelope. We used HEK293T cell lines stably expressing shRNA against Hop, emerin and a non-targeting control alongside the over expression of Hop in HEK293 cells to determine the effect of Hop levels on emerin expression and vice versa via Western blotting. The effect of Hop on the localization of emerin was assessed via subcellullar fractionation and confocal microscopy, while the impact on the structure of the nucleus was determined by transmission electron microscopy (TEM). We established that the depletion of Hop using shRNA and the over expression of Hop both result in the proteasomal and lysosomal degradation of emerin. Co-immunoprecipitation assays confirmed that Hop and emerin are in a common complex, which was not dependent on the presence of Hsp90. Loss of Hop or emerin led to a deformation of nuclear structure and a statistically significant decrease in nuclear size compared to control cells and was associated with an increase in the levels of nuclear protein, lamin A-C. Loss of emerin and Hop resulted in increased long term cell survival, but only after restriction of the nucleus when the cells had migrated across a transwell membrane. Taken together, the results obtained suggest that Hop acts as a scaffold for the stabilization of emerin and that the effects of Hop depletion on the structure of the nucleus and long term survival are mediated via the depletion of emerin. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2017
- Full Text:
- Date Issued: 2017
- Authors: Kituyi, Sarah Naulikha
- Date: 2017
- Subjects: Heat shock proteins , Nuclear structure , Nuclear membranes , Cancer Treatment , Molecular chaperones , Cytoskeleton , Cytoplasm
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/59230 , vital:27485 , DOI 10.21504/10962/59230
- Description: A vital component of the integral nuclear membrane is emerin, a Lamin Emerin and Man1 (LEM) domain protein whose concentration determines the levels of partner proteins that together constitute the structure of the nuclear envelope. Deficiencies in any of these proteins causes the failure of the structure and assembly and disassembly of the nuclear envelope, which disrupts chromosome segregation and nuclear compartmentalization that are both associated with disease. Emerin also localizes in the cytoplasm where it is implicated in the structure of the cytoskeleton via interaction with tubulin and actin and thus its deficiency may equally contribute to the collapse of the cytoskeleton. The Hsp70-Hsp90 organising protein (Hop) functions as a cochaperone for entry of client proteins into the Hsp90 folding cycle. Hop is upregulated in cancer and regulates a number of cell biology processes via interactions with proteins independently of Hsp90. In a previous study using global whole cell mass spectrometry, emerin was shown to be the most significantly down regulated protein in Hop depleted cell lysates. In this current study, it was postulated that emerin interacts with Hop, and this interaction regulates the stability, and level of emerin in the nucleus which impacts on the structure of the nuclear envelope. We used HEK293T cell lines stably expressing shRNA against Hop, emerin and a non-targeting control alongside the over expression of Hop in HEK293 cells to determine the effect of Hop levels on emerin expression and vice versa via Western blotting. The effect of Hop on the localization of emerin was assessed via subcellullar fractionation and confocal microscopy, while the impact on the structure of the nucleus was determined by transmission electron microscopy (TEM). We established that the depletion of Hop using shRNA and the over expression of Hop both result in the proteasomal and lysosomal degradation of emerin. Co-immunoprecipitation assays confirmed that Hop and emerin are in a common complex, which was not dependent on the presence of Hsp90. Loss of Hop or emerin led to a deformation of nuclear structure and a statistically significant decrease in nuclear size compared to control cells and was associated with an increase in the levels of nuclear protein, lamin A-C. Loss of emerin and Hop resulted in increased long term cell survival, but only after restriction of the nucleus when the cells had migrated across a transwell membrane. Taken together, the results obtained suggest that Hop acts as a scaffold for the stabilization of emerin and that the effects of Hop depletion on the structure of the nucleus and long term survival are mediated via the depletion of emerin. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2017
- Full Text:
- Date Issued: 2017