Modelling and investigating primary beam effects of reflector antenna arrays
- Authors: Iheanetu, Kelachukwu
- Date: 2020
- Subjects: Antennas, Reflector , Radio telescopes , Astronomical instruments -- Calibration , Holography , Polynomials , Very large array telescopes -- South Africa , Astronomy -- Data processing , Primary beam effects , Jacobi-Bessel pattern , Cassbeam software , MeerKAT telescope
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/147425 , vital:38635
- Description: Signals received by a radio telescope are always affected by propagation and instrumental effects. These effects need to be modelled and accounted for during the process of calibration. The primary beam (PB) of the antenna is one major instrumental effect that needs to be accounted for during calibration. Producing accurate models of the radio antenna PB is crucial, and many approaches (like electromagnetic and optical simulations) have been used to model it. The cos³ function, Jacobi-Bessel pattern, characteristic basis function patterns (CBFP) and Cassbeam software (which uses optical ray-tracing with antenna parameters) have also been used to model it. These models capture the basic PB effects. Real-life PB patterns differ from these models due to various subtle effects such as mechanical deformation and effects introduced into the PB due to standing waves that exist in reflector antennas. The actual patterns can be measured via a process called astro-holography (or holography), but this is subject to noise, radio frequency interference, and other measurement errors. In our approach, we use principal component analysis and Zernike polynomials to model the PBs of the Very Large Array (VLA) and the MeerKAT telescopes from their holography measured data. The models have reconstruction errors of less than 5% at a compression factor of approximately 98% for both arrays. We also present steps that can be used to generate accurate beam models for any telescope (independent of its design) based on holography measured data. Analysis of the VLA measured PBs revealed that the graph of the beam sizes (and centre offset positions) have a fast oscillating trend (superimposed on a slow trend) with frequency. This spectral behaviour we termed ripple or characteristic effects. Most existing PB models that are used in calibrating VLA data do not incorporate these direction dependent effects (DDEs). We investigate the impact of using PB models that ignore this DDE in continuum calibration and imaging via simulations. Our experiments show that, although these effects translate into less than 10% errors in source flux recovery, they do lead to 30% reduction in the dynamic range. To prepare data for Hi and radio halo (faint emissions) science analysis requires carrying out foreground subtraction of bright (continuum) sources. We investigate the impact of using beam models that ignore these ripple effects during continuum subtraction. These show that using PB models which completely ignore the ripple effects in continuum subtraction could translate to error of more to 30% in the recovered Hi spectral properties. This implies that science inferences drawn from the results for Hi studies could have errors of the same magnitude.
- Full Text:
- Date Issued: 2020
- Authors: Iheanetu, Kelachukwu
- Date: 2020
- Subjects: Antennas, Reflector , Radio telescopes , Astronomical instruments -- Calibration , Holography , Polynomials , Very large array telescopes -- South Africa , Astronomy -- Data processing , Primary beam effects , Jacobi-Bessel pattern , Cassbeam software , MeerKAT telescope
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/147425 , vital:38635
- Description: Signals received by a radio telescope are always affected by propagation and instrumental effects. These effects need to be modelled and accounted for during the process of calibration. The primary beam (PB) of the antenna is one major instrumental effect that needs to be accounted for during calibration. Producing accurate models of the radio antenna PB is crucial, and many approaches (like electromagnetic and optical simulations) have been used to model it. The cos³ function, Jacobi-Bessel pattern, characteristic basis function patterns (CBFP) and Cassbeam software (which uses optical ray-tracing with antenna parameters) have also been used to model it. These models capture the basic PB effects. Real-life PB patterns differ from these models due to various subtle effects such as mechanical deformation and effects introduced into the PB due to standing waves that exist in reflector antennas. The actual patterns can be measured via a process called astro-holography (or holography), but this is subject to noise, radio frequency interference, and other measurement errors. In our approach, we use principal component analysis and Zernike polynomials to model the PBs of the Very Large Array (VLA) and the MeerKAT telescopes from their holography measured data. The models have reconstruction errors of less than 5% at a compression factor of approximately 98% for both arrays. We also present steps that can be used to generate accurate beam models for any telescope (independent of its design) based on holography measured data. Analysis of the VLA measured PBs revealed that the graph of the beam sizes (and centre offset positions) have a fast oscillating trend (superimposed on a slow trend) with frequency. This spectral behaviour we termed ripple or characteristic effects. Most existing PB models that are used in calibrating VLA data do not incorporate these direction dependent effects (DDEs). We investigate the impact of using PB models that ignore this DDE in continuum calibration and imaging via simulations. Our experiments show that, although these effects translate into less than 10% errors in source flux recovery, they do lead to 30% reduction in the dynamic range. To prepare data for Hi and radio halo (faint emissions) science analysis requires carrying out foreground subtraction of bright (continuum) sources. We investigate the impact of using beam models that ignore these ripple effects during continuum subtraction. These show that using PB models which completely ignore the ripple effects in continuum subtraction could translate to error of more to 30% in the recovered Hi spectral properties. This implies that science inferences drawn from the results for Hi studies could have errors of the same magnitude.
- Full Text:
- Date Issued: 2020
Mothers’ perceptions of the effects of the babies in mind programme on maternal mental health and mother-infant attachment: a South African narrative study
- Naicker, Samantha, Cronje, Johan
- Authors: Naicker, Samantha , Cronje, Johan
- Date: 2020
- Subjects: Mother and infant
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/46414 , vital:39590
- Description: The focus of this study is on mothers, motherhood and the Babies in Mind programme as an early intervention strategy for mothers in South Africa. The rate of maternal mental ill health in our country is alarming. Research consistently confirms that maternal mental health directly affects infant and child mental health. One of the major determinants of mental health is mother-infant attachment. Studies have indicated the range of deleterious effects that maternal mental ill-health and mother-infant attachment issues have on offspring from infancy to adulthood. This has implications for the mental health of future generations and society at large. Researchers have called for evidence-based interventions that address maternal mental health and mother-infant attachment, especially in developing countries. South Africa has no national prevention or treatment programme to address these needs. This study investigated the Babies in Mind programme as an early intervention option to address the gap in promoting maternal mental health and mother-infant attachment. A social constructionist, narrative study was employed to meet the objectives of the study. The aim was to explore mothers’ perceptions of the impact of the Babies in Mind programme, with particular reference to their mental health and their relationships to their infants. Focus was placed on understanding the social constructions of motherhood at the community level and how these constructions were reconstructed through the programme. Purposive sampling was employed and focus groups were conducted to collect the relevant data. The data was analysed using thematic analysis. The findings indicated that mothers’ experiences of the Babies in Mind programme were positive and there were improvements in their mental health and relationships to their infants. A relationship model for mothers was developed based on the themes that emerged from the data analysis. A platform for continued support and discussion was organised via a social media (Whatsapp) support group. Twelve 7guidelines were suggested for the implementation of intervention programmes such as the Babies in Mind programme at the community level.
- Full Text:
- Date Issued: 2020
- Authors: Naicker, Samantha , Cronje, Johan
- Date: 2020
- Subjects: Mother and infant
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/46414 , vital:39590
- Description: The focus of this study is on mothers, motherhood and the Babies in Mind programme as an early intervention strategy for mothers in South Africa. The rate of maternal mental ill health in our country is alarming. Research consistently confirms that maternal mental health directly affects infant and child mental health. One of the major determinants of mental health is mother-infant attachment. Studies have indicated the range of deleterious effects that maternal mental ill-health and mother-infant attachment issues have on offspring from infancy to adulthood. This has implications for the mental health of future generations and society at large. Researchers have called for evidence-based interventions that address maternal mental health and mother-infant attachment, especially in developing countries. South Africa has no national prevention or treatment programme to address these needs. This study investigated the Babies in Mind programme as an early intervention option to address the gap in promoting maternal mental health and mother-infant attachment. A social constructionist, narrative study was employed to meet the objectives of the study. The aim was to explore mothers’ perceptions of the impact of the Babies in Mind programme, with particular reference to their mental health and their relationships to their infants. Focus was placed on understanding the social constructions of motherhood at the community level and how these constructions were reconstructed through the programme. Purposive sampling was employed and focus groups were conducted to collect the relevant data. The data was analysed using thematic analysis. The findings indicated that mothers’ experiences of the Babies in Mind programme were positive and there were improvements in their mental health and relationships to their infants. A relationship model for mothers was developed based on the themes that emerged from the data analysis. A platform for continued support and discussion was organised via a social media (Whatsapp) support group. Twelve 7guidelines were suggested for the implementation of intervention programmes such as the Babies in Mind programme at the community level.
- Full Text:
- Date Issued: 2020
Navigating Blackness in the African Diaspora
- Authors: Yates, Sarah
- Date: 2020
- Subjects: Ellison, Ralph. Invisible man , Everett, Percival. Erasure , Wicomb, Zoe. Playing in the light , Bulawayo, NoViolet. We need new names , Africans in literature , Race in literature , African fiction (English) -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/145720 , vital:38461
- Description: This thesis offers a comparative reading of Ralph Ellison’s Invisible Man, Percival Everett’s Erasure, Zoë Wicomb’s Playing in the Light and NoViolet Bulawayo’s We Need New Names in order to explore the diversity of subjectivities included within the terms ‘African’ and ‘black’ and to argue for the necessity of renewed definitions of Africa(nness) and blackness which allow for diverse and fluid representations. The diverse historical and political contexts in which these novels are published, as well as the critical and theoretical discussions which surround them demonstrate an evolution in literary portrayals of identity politics. As the categories of race and nation become more fluid, so too do narrative forms. In particular, this thesis is interested in the textual strategies authors use to navigate the various ways in which depictions of blackness continue to be restricted by racism, stereotypes, and the dynamics of a global literary market. As portrayals and discussions of identity politics proliferate in popular culture, they become increasingly commodified, and therefore increasingly restricted by the market.
- Full Text:
- Date Issued: 2020
- Authors: Yates, Sarah
- Date: 2020
- Subjects: Ellison, Ralph. Invisible man , Everett, Percival. Erasure , Wicomb, Zoe. Playing in the light , Bulawayo, NoViolet. We need new names , Africans in literature , Race in literature , African fiction (English) -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/145720 , vital:38461
- Description: This thesis offers a comparative reading of Ralph Ellison’s Invisible Man, Percival Everett’s Erasure, Zoë Wicomb’s Playing in the Light and NoViolet Bulawayo’s We Need New Names in order to explore the diversity of subjectivities included within the terms ‘African’ and ‘black’ and to argue for the necessity of renewed definitions of Africa(nness) and blackness which allow for diverse and fluid representations. The diverse historical and political contexts in which these novels are published, as well as the critical and theoretical discussions which surround them demonstrate an evolution in literary portrayals of identity politics. As the categories of race and nation become more fluid, so too do narrative forms. In particular, this thesis is interested in the textual strategies authors use to navigate the various ways in which depictions of blackness continue to be restricted by racism, stereotypes, and the dynamics of a global literary market. As portrayals and discussions of identity politics proliferate in popular culture, they become increasingly commodified, and therefore increasingly restricted by the market.
- Full Text:
- Date Issued: 2020
Negotiating family planning messages among Malawian men: A case study of vasectomy messages aimed at men in the Dedza and Karonga districts of Malawi
- Authors: Ntaba, Jolly Maxwell
- Date: 2020
- Subjects: Social marketing -- Malawi , Vasectomy -- Social aspects -- Malawi , Malawians -- Attitudes , Men -- Malawi -- Attitudes , Men -- Conduct of life -- Malawi , Men -- Sexual behavior -- Malawi , Masculinity -- Malawi , Reproductive health in mass media -- Malawi , Reproductive health services -- Malawi
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167200 , vital:41446
- Description: Since the 1990s, vasectomy, the principal non-barrier method of contraception offered to men, has been vigorously promoted in Malawi, as a safe, effective and inexpensive form of birth control. Despite this marketing, the method has been chosen by only an estimated 0.01% of men in Malawi. This compares to about 11% of contraceptive using Malawian women, who have opted for tubal ligation, a more expensive and hazardous surgical procedure. Previous studies into this low uptake of vasectomy among men in Malawi, and other studies that have explored why no African country currently has a vasectomy rate of more than 1% of men, implicate cultural beliefs and traditional social practices among the key barriers to the diffusion of this particular innovation i.e. this method of contraception. Campaigns share new information in the hope that they will shift their audiences’ knowledge, and lead to changes in attitudes and practices, including the uptake of vasectomy. Social Marketing campaigns, even when they set out to explicitly accommodate these beliefs and challenge particular practices in order to promote various methods of contraception, are often inadequately conceived and sometimes poorly executed. Drawing on well-established theoretical perspectives developed by Cultural Studies scholars, including Reception Analysis and Thematic Analysis, this study investigates how men in two purposively selected districts of Karonga and Dedza in Malawi, interpret Social Marketing messages encouraging them to undergo vasectomies. The study examines key media texts and the nature of the involvement of a group of peer educators, dubbed ‘male champions’ in a 2017-2018 campaign by one of the leading Malawian providers of family planning services, the NGO Banja La Mtsogolo (BLM), to promote vasectomy. This is a purely qualitative case study that seeks to understand why these often-well-resourced campaigns have so little impact on the behaviour change they hope to inspire. Through individual interviews with the campaign’s designers, implementers, peer educators, focus group discussions with the campaign’s audiences, a close reading of texts used in the campaign, and observation, this study explores the circuits of communication and culture, through mechanisms of resonance, disconnection and even cognitive dissonance between the ‘encoders’ of the family planning messages and the decoders i.e. the intended audiences of the campaign. The study argues that as a result of several ‘modernist’ assumptions and outlooks, the campaign was unable to fully grasp the complex and contextually nuanced socio-cultural practices that factor into consideration of the campaign’s messages and the non-adoption of the proposed vasectomy method. The study further reveals, as many other studies have also observed, that the interpretation of the text promoting vasectomy is a complex process that is significantly shaped by the worldviews and lived experiences of the audiences. These views, as this study explores, are often complex and contradictory, interfacing aspirations of modernity with deeply held ‘traditional’ beliefs and practices. Although the campaigns are effective at transferring knowledge – it finds most targeted men have a relatively good understanding of the method and its efficacy – their prevailing socio-cultural attitudes and dispositions provide a strong countervailing discourse to the preferred reading of the campaign messages. This discourse exhorts having children, or the capacity to have children, even after a man has had several before, in current or previous marriages, or even in old age, as desirable and ‘rational’. The study therefore proposes, arising out of this detailed ethnographic research, a revised approach that argues that several social and cultural ‘vectors’ or ‘spheres of influence' need to be considered in new ways, in order to develop meaningful interventions in the promotion of vasectomy. This includes specific strategies to understand and challenge: 1. The enduring power of social stigma and scorn, and the notion of social shame. 2. The deep interplay between fertility and having children to notions of marriage, even in second or third marriages, and the interplay with perceptions of economic ‘value’ of children in the domestic political economy of marriage. 3. The embedded nature of provable fertility to notions of manhood. 4. The complex and nuanced involvement, at many levels, of broader social/family structures/personages in ‘personal’ decisions. 5. Forms of ‘hyperbolic discounting’, i.e. the calculating of precarious futures in various scenarios and its impact on current shorter-term calculations and gratifications. 6. Unusually high rates of infidelity in marriage, and seemingly low levels of trust in many partnerships. 7. The key role of interpersonal communication, i.e. the face-to-face elements of what are usually media-centric Social Marketing campaigns. The study recommends a more layered and nuanced approach to the promotion of vasectomy, propelled by a deeper understanding of these kinds of contexts and the interpretive power of the intended audience, as well as more nuanced segmentation of audiences, and more judicious use of peer-educators to support and deepen the mass media components of these communication campaigns.
- Full Text:
- Date Issued: 2020
- Authors: Ntaba, Jolly Maxwell
- Date: 2020
- Subjects: Social marketing -- Malawi , Vasectomy -- Social aspects -- Malawi , Malawians -- Attitudes , Men -- Malawi -- Attitudes , Men -- Conduct of life -- Malawi , Men -- Sexual behavior -- Malawi , Masculinity -- Malawi , Reproductive health in mass media -- Malawi , Reproductive health services -- Malawi
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167200 , vital:41446
- Description: Since the 1990s, vasectomy, the principal non-barrier method of contraception offered to men, has been vigorously promoted in Malawi, as a safe, effective and inexpensive form of birth control. Despite this marketing, the method has been chosen by only an estimated 0.01% of men in Malawi. This compares to about 11% of contraceptive using Malawian women, who have opted for tubal ligation, a more expensive and hazardous surgical procedure. Previous studies into this low uptake of vasectomy among men in Malawi, and other studies that have explored why no African country currently has a vasectomy rate of more than 1% of men, implicate cultural beliefs and traditional social practices among the key barriers to the diffusion of this particular innovation i.e. this method of contraception. Campaigns share new information in the hope that they will shift their audiences’ knowledge, and lead to changes in attitudes and practices, including the uptake of vasectomy. Social Marketing campaigns, even when they set out to explicitly accommodate these beliefs and challenge particular practices in order to promote various methods of contraception, are often inadequately conceived and sometimes poorly executed. Drawing on well-established theoretical perspectives developed by Cultural Studies scholars, including Reception Analysis and Thematic Analysis, this study investigates how men in two purposively selected districts of Karonga and Dedza in Malawi, interpret Social Marketing messages encouraging them to undergo vasectomies. The study examines key media texts and the nature of the involvement of a group of peer educators, dubbed ‘male champions’ in a 2017-2018 campaign by one of the leading Malawian providers of family planning services, the NGO Banja La Mtsogolo (BLM), to promote vasectomy. This is a purely qualitative case study that seeks to understand why these often-well-resourced campaigns have so little impact on the behaviour change they hope to inspire. Through individual interviews with the campaign’s designers, implementers, peer educators, focus group discussions with the campaign’s audiences, a close reading of texts used in the campaign, and observation, this study explores the circuits of communication and culture, through mechanisms of resonance, disconnection and even cognitive dissonance between the ‘encoders’ of the family planning messages and the decoders i.e. the intended audiences of the campaign. The study argues that as a result of several ‘modernist’ assumptions and outlooks, the campaign was unable to fully grasp the complex and contextually nuanced socio-cultural practices that factor into consideration of the campaign’s messages and the non-adoption of the proposed vasectomy method. The study further reveals, as many other studies have also observed, that the interpretation of the text promoting vasectomy is a complex process that is significantly shaped by the worldviews and lived experiences of the audiences. These views, as this study explores, are often complex and contradictory, interfacing aspirations of modernity with deeply held ‘traditional’ beliefs and practices. Although the campaigns are effective at transferring knowledge – it finds most targeted men have a relatively good understanding of the method and its efficacy – their prevailing socio-cultural attitudes and dispositions provide a strong countervailing discourse to the preferred reading of the campaign messages. This discourse exhorts having children, or the capacity to have children, even after a man has had several before, in current or previous marriages, or even in old age, as desirable and ‘rational’. The study therefore proposes, arising out of this detailed ethnographic research, a revised approach that argues that several social and cultural ‘vectors’ or ‘spheres of influence' need to be considered in new ways, in order to develop meaningful interventions in the promotion of vasectomy. This includes specific strategies to understand and challenge: 1. The enduring power of social stigma and scorn, and the notion of social shame. 2. The deep interplay between fertility and having children to notions of marriage, even in second or third marriages, and the interplay with perceptions of economic ‘value’ of children in the domestic political economy of marriage. 3. The embedded nature of provable fertility to notions of manhood. 4. The complex and nuanced involvement, at many levels, of broader social/family structures/personages in ‘personal’ decisions. 5. Forms of ‘hyperbolic discounting’, i.e. the calculating of precarious futures in various scenarios and its impact on current shorter-term calculations and gratifications. 6. Unusually high rates of infidelity in marriage, and seemingly low levels of trust in many partnerships. 7. The key role of interpersonal communication, i.e. the face-to-face elements of what are usually media-centric Social Marketing campaigns. The study recommends a more layered and nuanced approach to the promotion of vasectomy, propelled by a deeper understanding of these kinds of contexts and the interpretive power of the intended audience, as well as more nuanced segmentation of audiences, and more judicious use of peer-educators to support and deepen the mass media components of these communication campaigns.
- Full Text:
- Date Issued: 2020
NFComms: A synchronous communication framework for the CPU-NFP heterogeneous system
- Authors: Pennefather, Sean
- Date: 2020
- Subjects: Network processors , Computer programming , Parallel processing (Electronic computers) , Netronome
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/144181 , vital:38318
- Description: This work explores the viability of using a Network Flow Processor (NFP), developed by Netronome, as a coprocessor for the construction of a CPU-NFP heterogeneous platform in the domain of general processing. When considering heterogeneous platforms involving architectures like the NFP, the communication framework provided is typically represented as virtual network interfaces and is thus not suitable for generic communication. To enable a CPU-NFP heterogeneous platform for use in the domain of general computing, a suitable generic communication framework is required. A feasibility study for a suitable communication medium between the two candidate architectures showed that a generic framework that conforms to the mechanisms dictated by Communicating Sequential Processes is achievable. The resulting NFComms framework, which facilitates inter- and intra-architecture communication through the use of synchronous message passing, supports up to 16 unidirectional channels and includes queuing mechanisms for transparently supporting concurrent streams exceeding the channel count. The framework has a minimum latency of between 15.5 μs and 18 μs per synchronous transaction and can sustain a peak throughput of up to 30 Gbit/s. The framework also supports a runtime for interacting with the Go programming language, allowing user-space processes to subscribe channels to the framework for interacting with processes executing on the NFP. The viability of utilising a heterogeneous CPU-NFP system for use in the domain of general and network computing was explored by introducing a set of problems or applications spanning general computing, and network processing. These were implemented on the heterogeneous architecture and benchmarked against equivalent CPU-only and CPU/GPU solutions. The results recorded were used to form an opinion on the viability of using an NFP for general processing. It is the author’s opinion that, beyond very specific use cases, it appears that the NFP-400 is not currently a viable solution as a coprocessor in the field of general computing. This does not mean that the proposed framework or the concept of a heterogeneous CPU-NFP system should be discarded as such a system does have acceptable use in the fields of network and stream processing. Additionally, when comparing the recorded limitations to those seen during the early stages of general purpose GPU development, it is clear that general processing on the NFP is currently in a similar state.
- Full Text:
- Date Issued: 2020
- Authors: Pennefather, Sean
- Date: 2020
- Subjects: Network processors , Computer programming , Parallel processing (Electronic computers) , Netronome
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/144181 , vital:38318
- Description: This work explores the viability of using a Network Flow Processor (NFP), developed by Netronome, as a coprocessor for the construction of a CPU-NFP heterogeneous platform in the domain of general processing. When considering heterogeneous platforms involving architectures like the NFP, the communication framework provided is typically represented as virtual network interfaces and is thus not suitable for generic communication. To enable a CPU-NFP heterogeneous platform for use in the domain of general computing, a suitable generic communication framework is required. A feasibility study for a suitable communication medium between the two candidate architectures showed that a generic framework that conforms to the mechanisms dictated by Communicating Sequential Processes is achievable. The resulting NFComms framework, which facilitates inter- and intra-architecture communication through the use of synchronous message passing, supports up to 16 unidirectional channels and includes queuing mechanisms for transparently supporting concurrent streams exceeding the channel count. The framework has a minimum latency of between 15.5 μs and 18 μs per synchronous transaction and can sustain a peak throughput of up to 30 Gbit/s. The framework also supports a runtime for interacting with the Go programming language, allowing user-space processes to subscribe channels to the framework for interacting with processes executing on the NFP. The viability of utilising a heterogeneous CPU-NFP system for use in the domain of general and network computing was explored by introducing a set of problems or applications spanning general computing, and network processing. These were implemented on the heterogeneous architecture and benchmarked against equivalent CPU-only and CPU/GPU solutions. The results recorded were used to form an opinion on the viability of using an NFP for general processing. It is the author’s opinion that, beyond very specific use cases, it appears that the NFP-400 is not currently a viable solution as a coprocessor in the field of general computing. This does not mean that the proposed framework or the concept of a heterogeneous CPU-NFP system should be discarded as such a system does have acceptable use in the fields of network and stream processing. Additionally, when comparing the recorded limitations to those seen during the early stages of general purpose GPU development, it is clear that general processing on the NFP is currently in a similar state.
- Full Text:
- Date Issued: 2020
Non-marital fertility in South Africa: trends, determinants and implications
- Authors: Kara, Reesha
- Date: 2020
- Subjects: Fertility, Human -- South Africa , Child rearing -- South Africa , Parenting -- South Africa , Motherhood -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/165620 , vital:41264
- Description: Background: Non-martial fertility is traditionally associated with teenage pregnancy however international and South African literature has detailed increases in the number of adult women who are having children outside of a marriage. South African literature on non-marital fertility is sparse as it lacks a national overview of the trends and determinants of non-marital fertility among women aged 30 and older. The aim of this study was to present a national overview of non-marital fertility among women aged 30 and older. South African’s attitudes to and opinions of non-marital fertility were also investigated, and the lived realities of older mothers were explored. Methods: A mixed-methods research design was employed where the General Household Survey, National Income Dynamics Study and the South African Social Attitudes Survey were the main data sources. Using these data sets, descriptive and inferential statistics were computed using Stata. Using purposive and snowball sampling, four never-married older mothers (NMOMs) from KwaZulu-Natal (Durban) were identified as research participants. The in-depth life histories of these women were collected through face-to- face semi-structured interviews. Results: The results show an 18.43% increase in never-married mothers aged 15- 49 between 2002 and 2017 and interestingly, this increase is not necessarily driven by older mothers (30-49). NMOMs belonged to households with a lower average per capita total monthly household income (R1873.91) compared to all mothers aged 30-49 (R3428.76). NMOMs were also more likely to live in female-headed households (89.52%), to be household heads (64.22%) and to live in traditional areas (35.72%). Between 2002 and 2017, there was a 76.76% increase in mothers (aged 30-49) who were never married and a 7.74% decrease in those who were married, indicating a change in the marital profile of mothers. Despite this national increase in non-marital fertility, South African’s believe that premarital sexual activity is wrong, and that childbearing should take place within a marriage. Similar sentiments were echoed in the in-depth life histories as being the sole breadwinner and primary caregiver, the research participants experienced challenges as single mothers. Conclusion and recommendations: The study has found that there has been an increase in non-marital fertility in South Africa between 2002 and 2017 and that there is an economic element to non-marital fertility in the country. Additional research into non-marital fertility at a national level is recommended with a focus on all women aged 15-49.
- Full Text:
- Date Issued: 2020
- Authors: Kara, Reesha
- Date: 2020
- Subjects: Fertility, Human -- South Africa , Child rearing -- South Africa , Parenting -- South Africa , Motherhood -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/165620 , vital:41264
- Description: Background: Non-martial fertility is traditionally associated with teenage pregnancy however international and South African literature has detailed increases in the number of adult women who are having children outside of a marriage. South African literature on non-marital fertility is sparse as it lacks a national overview of the trends and determinants of non-marital fertility among women aged 30 and older. The aim of this study was to present a national overview of non-marital fertility among women aged 30 and older. South African’s attitudes to and opinions of non-marital fertility were also investigated, and the lived realities of older mothers were explored. Methods: A mixed-methods research design was employed where the General Household Survey, National Income Dynamics Study and the South African Social Attitudes Survey were the main data sources. Using these data sets, descriptive and inferential statistics were computed using Stata. Using purposive and snowball sampling, four never-married older mothers (NMOMs) from KwaZulu-Natal (Durban) were identified as research participants. The in-depth life histories of these women were collected through face-to- face semi-structured interviews. Results: The results show an 18.43% increase in never-married mothers aged 15- 49 between 2002 and 2017 and interestingly, this increase is not necessarily driven by older mothers (30-49). NMOMs belonged to households with a lower average per capita total monthly household income (R1873.91) compared to all mothers aged 30-49 (R3428.76). NMOMs were also more likely to live in female-headed households (89.52%), to be household heads (64.22%) and to live in traditional areas (35.72%). Between 2002 and 2017, there was a 76.76% increase in mothers (aged 30-49) who were never married and a 7.74% decrease in those who were married, indicating a change in the marital profile of mothers. Despite this national increase in non-marital fertility, South African’s believe that premarital sexual activity is wrong, and that childbearing should take place within a marriage. Similar sentiments were echoed in the in-depth life histories as being the sole breadwinner and primary caregiver, the research participants experienced challenges as single mothers. Conclusion and recommendations: The study has found that there has been an increase in non-marital fertility in South Africa between 2002 and 2017 and that there is an economic element to non-marital fertility in the country. Additional research into non-marital fertility at a national level is recommended with a focus on all women aged 15-49.
- Full Text:
- Date Issued: 2020
Not Yet Uhuru! Attuning to, re-imagining and regenerating transgressive decolonial pedagogical praxis across times Khapa(ring) the rising cultures of change drivers in contemporary South Africa
- Authors: Kulundu-Bolus, Injairu
- Date: 2020
- Subjects: Not Yet Uhuru (Arts Project) , Anti-imperialist movements -- South Africa , Education -- Social aspects -- South Africa , Social change -- South Africa , Education -- Philosophy -- South Africa , Arts and society -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/166081 , vital:41327 , 10.21504/10962/166081
- Description: The “Not yet Uhuru!” project positions itself as emancipatory African research in motion. It is a regenerative project that responds to the concern that whilst dominant discourses can articulate what African states, societies and economies are not, we still know very little about what they actually are. This is a particularly important gap in how research on Africa is conceptualised, especially as it pertains to apprehending the futures that the majority of young people on the continent are instinctively leading themselves to (Mbembe, 2001, p.9). The project seeks to forgo youth development strategies that act as a form of containment by prescribing normative aspects of citizenship on young leaders in ways that stifle the transgressive impulses they have reason to value (Kelley in Tuck and Yang, 2014, p.89). The study traces rising cultures in transgressive decolonial pedagogical praxis across times, as a way of “khapa(ring)” or accompanying the contemporary questions that Change Drivers in South Africa hold at the edge of their praxis. The study co-conspired with 21 Change Drivers in South Africa who were interested in regenerating and re-imagining what transgressive decolonial praxis could be in these times based on their experiences and learnings. Residential art-based workshops that explored each co-conspirator’s offerings on the subject were distilled through the medium of film. These in turn were analysed using an “ethics of attunement” that produced songs as a reflexive pedagogical tool (Lispari, 2014, p.176). Sharing the resonate echoes of their praxis through song created another iterative reflection on their praxis two years after their initial offerings. As a way of weaving together the findings with a historical perspective, the resonant praxis of Change Drivers was put into conversation with three unconventional reviews that trace impulses around transgressive decolonial pedagogical praxis through fictional texts, political theory, poetry and intergenerational analysis, in order to surface resonant themes in praxis that echo across different times in history. This methodology sought to engage the question of the archive in pluriversal ways that appealed to different sensibilities, including the imaginative and hermeneutical, the traditionally analytical as well as the gifts of the lyrical and the erotic as different conceptual threads needed to resource the study. The reviews additionally spanned periods in the history of the continent that hold questions around precolonial and nascent colonial encounters, efforts to transgress within the liberatory movements and the intergenerational transmissions embedded in women and queer people’s struggles. The themes that coalesced across times were leveraged into capsules of rising cultures that form an experimental nexus for the practice of transgressive decolonial pedagogical praxis that is already underway. These rising cultures were conceptualised as meditations on what it means to live into a vision of home built on the explorations of a paradigm of peace, humanness, pluriversality and decolonial love for those like and unlike us that strive for freedom on this continent (Dlala, 2017, p.52; Ndlovu- Gatsheni, 2013, p.142; Gqola, 2017, pp.197, 199). The rising ultures were reconciled through the creation of a litany that chronicles different refrains in transgressive decolonial pedagogical praxis in contemporary times. The litany is a tool that charts particular experiences that are surfacing as symptomatic. It seeks to generously surface the contradictions that we are collectively starting to see past, whilst acknowledging the tensions that we need to straddle, integrate and navigate towards greater synthesis. The litany is an honest way of acknowledging the glimpses gained of who we are in this present moment, while we continually challenge ourselves to open up to questions about what it means to grapple towards decolonial futures. This stance has influenced my role as an educator to unconditionally embrace movements that already underway, and reflect these back to those that I am conspiring with in ways that promote an ethic of care, solidarity and critical engagement. The study celebrates what is possible when we do not theorise ourselves away from the questions embedded in our current praxis. This is an ethic that chooses to stay close to the phenomena arriving at present, whilst acknowledging the historical experiences that echo it as a collective pulse for meaningful experimentation and praxis. The study believes by being faithful to ways of amplifying, integrating and reflecting what has been emerging for us over time, we build our capacity to better respond with an ethic centred on transgressive decolonial pedagogical praxis. This is the kind of accompaniment and care that Change Drivers across the continent deserve as they make the way towards a future worthy of their longing (Rushdie, 1999).
- Full Text:
- Date Issued: 2020
- Authors: Kulundu-Bolus, Injairu
- Date: 2020
- Subjects: Not Yet Uhuru (Arts Project) , Anti-imperialist movements -- South Africa , Education -- Social aspects -- South Africa , Social change -- South Africa , Education -- Philosophy -- South Africa , Arts and society -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/166081 , vital:41327 , 10.21504/10962/166081
- Description: The “Not yet Uhuru!” project positions itself as emancipatory African research in motion. It is a regenerative project that responds to the concern that whilst dominant discourses can articulate what African states, societies and economies are not, we still know very little about what they actually are. This is a particularly important gap in how research on Africa is conceptualised, especially as it pertains to apprehending the futures that the majority of young people on the continent are instinctively leading themselves to (Mbembe, 2001, p.9). The project seeks to forgo youth development strategies that act as a form of containment by prescribing normative aspects of citizenship on young leaders in ways that stifle the transgressive impulses they have reason to value (Kelley in Tuck and Yang, 2014, p.89). The study traces rising cultures in transgressive decolonial pedagogical praxis across times, as a way of “khapa(ring)” or accompanying the contemporary questions that Change Drivers in South Africa hold at the edge of their praxis. The study co-conspired with 21 Change Drivers in South Africa who were interested in regenerating and re-imagining what transgressive decolonial praxis could be in these times based on their experiences and learnings. Residential art-based workshops that explored each co-conspirator’s offerings on the subject were distilled through the medium of film. These in turn were analysed using an “ethics of attunement” that produced songs as a reflexive pedagogical tool (Lispari, 2014, p.176). Sharing the resonate echoes of their praxis through song created another iterative reflection on their praxis two years after their initial offerings. As a way of weaving together the findings with a historical perspective, the resonant praxis of Change Drivers was put into conversation with three unconventional reviews that trace impulses around transgressive decolonial pedagogical praxis through fictional texts, political theory, poetry and intergenerational analysis, in order to surface resonant themes in praxis that echo across different times in history. This methodology sought to engage the question of the archive in pluriversal ways that appealed to different sensibilities, including the imaginative and hermeneutical, the traditionally analytical as well as the gifts of the lyrical and the erotic as different conceptual threads needed to resource the study. The reviews additionally spanned periods in the history of the continent that hold questions around precolonial and nascent colonial encounters, efforts to transgress within the liberatory movements and the intergenerational transmissions embedded in women and queer people’s struggles. The themes that coalesced across times were leveraged into capsules of rising cultures that form an experimental nexus for the practice of transgressive decolonial pedagogical praxis that is already underway. These rising cultures were conceptualised as meditations on what it means to live into a vision of home built on the explorations of a paradigm of peace, humanness, pluriversality and decolonial love for those like and unlike us that strive for freedom on this continent (Dlala, 2017, p.52; Ndlovu- Gatsheni, 2013, p.142; Gqola, 2017, pp.197, 199). The rising ultures were reconciled through the creation of a litany that chronicles different refrains in transgressive decolonial pedagogical praxis in contemporary times. The litany is a tool that charts particular experiences that are surfacing as symptomatic. It seeks to generously surface the contradictions that we are collectively starting to see past, whilst acknowledging the tensions that we need to straddle, integrate and navigate towards greater synthesis. The litany is an honest way of acknowledging the glimpses gained of who we are in this present moment, while we continually challenge ourselves to open up to questions about what it means to grapple towards decolonial futures. This stance has influenced my role as an educator to unconditionally embrace movements that already underway, and reflect these back to those that I am conspiring with in ways that promote an ethic of care, solidarity and critical engagement. The study celebrates what is possible when we do not theorise ourselves away from the questions embedded in our current praxis. This is an ethic that chooses to stay close to the phenomena arriving at present, whilst acknowledging the historical experiences that echo it as a collective pulse for meaningful experimentation and praxis. The study believes by being faithful to ways of amplifying, integrating and reflecting what has been emerging for us over time, we build our capacity to better respond with an ethic centred on transgressive decolonial pedagogical praxis. This is the kind of accompaniment and care that Change Drivers across the continent deserve as they make the way towards a future worthy of their longing (Rushdie, 1999).
- Full Text:
- Date Issued: 2020
On locating the experiences of second year science students from rural areas in Higher Education in the field of science: lived rural experiences
- Madondo, Nkosinathi Emmanuel
- Authors: Madondo, Nkosinathi Emmanuel
- Date: 2020
- Subjects: Science students -- South Africa , Rural college students -- South Africa , Science -- Study and teaching (Higher) -- South Africa , Curriculum change -- South Africa , Learning -- Evaluation , Social justice and education -- South Africa , Action research in education -- South Africa , Participant observation -- South Africa , Critical realism , Ethnoscience -- South Africa , Focus groups -- South Africa , Bernstein, Basil
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/145758 , vital:38464
- Description: This study was designed to investigate the experiences of Second Year Science students who come from rural backgrounds within a Higher Education context. The purpose of the study was to understand the enabling and/or constraining factors that influence the teaching and learning of Second Year Science students who come from rural contexts. Given this purpose, the participants that were considered relevant to answer the question: What are the enabling and constraining factors that influence teaching and learning of second year Science students who come from rural backgrounds at a South African University? were students from rural areas enrolled in the Faculty of Science at the research site, academic teachers and senior leaders’, and roles in providing enabling and/or constraining teaching and learning environment. The phenomenon under investigation was thus, the extent to which the teaching and learning environment, in the field of science, enable or constrain access to the Discourse of science for students who come from rural areas. To generate data, the study used focus group discussions, Participatory Learning and Action (PLA) tools as part of Participatory Action Research (PAR), digital documentaries, as well as academic teachers’ rich descriptions of the rationale for the design and delivery techniques of their modules by means of focus group interviews, as well as curriculum review documents. The purpose of Action Research (AR) in this study was to enable change by way of advancing a self-consciousness, envisaged to yield some action based on the enablements or constraints identified by the participants involved. Archer’s (1995, 1996) analytical dualism was used as the analytical framework to identify the interplay of structural, cultural and agential mechanisms shaping the emergence of, and practices associated with students’ experiences of the science curriculum and academic teachers’ observations of these experiences. Bernstein’s pedagogic device was also used to explain the options that academic teachers have to shape the curriculum, a curriculum that would reflect the experiences of the heterogeneity of the student cohort when designing their course guides, for example. The analysis thus used Archer’s (1995, 1996) Morphogenesis/Morphostasis framework through which change or non-change can be observed over time. The work of Bhaskar (1975, 1979) was important in this regard because it allows us to separate what we see, experience and understand (in the transitive world) from what is independent of our thoughts and experiences (the intransitive world) when conducting scientific enquiry, so that we are able to deduce the ‘real’ factors that enable and constrain the events and experiences being studied. Since there are multiple mechanisms operative that can act to include or exclude students in Science classrooms, particularly those who come from lower class, including those who come from rural areas, this study focuses on curriculum as one mechanism that can be at play in the problem of exclusion. In this study, I argue, the University and its structures like curriculum are not neutral but are historical, cultural, political and social, which is why persistent apartheid legacy and coloniality were seen as playing a role in how the curriculum is designed and thus enacted. This is the reason, a decolonial gaze was adopted in order to engage with social justice issues and in the process tease out the social relations of knowledge practices. A decolonial gaze provided a way to re-describe the structuring of the curriculum and the contradictions it sets up for black students, particularly those who come from lower class backgrounds, including those from rural areas. Findings reveal that the way in which the science curriculum (and/or teaching and learning) is structured, and thus enacted, tends to favour certain worldviews to the exclusion of others. Also, findings show that when students are presented with knowledge that seems completely separate from them, their identities, their heritage, their backgrounds and value systems, accessing that knowledge can seem inordinately difficult. Consequently, students from rural contexts are often alienated, because the “world” they bring and know is often not considered part of the starting point, neither is it seen as relevant when teaching the science curriculum. There is therefore a clear need to bring something ‘from home’ into our teaching as a means of reassuring students that all is not foreign and that what they already know is valuable.
- Full Text:
- Date Issued: 2020
- Authors: Madondo, Nkosinathi Emmanuel
- Date: 2020
- Subjects: Science students -- South Africa , Rural college students -- South Africa , Science -- Study and teaching (Higher) -- South Africa , Curriculum change -- South Africa , Learning -- Evaluation , Social justice and education -- South Africa , Action research in education -- South Africa , Participant observation -- South Africa , Critical realism , Ethnoscience -- South Africa , Focus groups -- South Africa , Bernstein, Basil
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/145758 , vital:38464
- Description: This study was designed to investigate the experiences of Second Year Science students who come from rural backgrounds within a Higher Education context. The purpose of the study was to understand the enabling and/or constraining factors that influence the teaching and learning of Second Year Science students who come from rural contexts. Given this purpose, the participants that were considered relevant to answer the question: What are the enabling and constraining factors that influence teaching and learning of second year Science students who come from rural backgrounds at a South African University? were students from rural areas enrolled in the Faculty of Science at the research site, academic teachers and senior leaders’, and roles in providing enabling and/or constraining teaching and learning environment. The phenomenon under investigation was thus, the extent to which the teaching and learning environment, in the field of science, enable or constrain access to the Discourse of science for students who come from rural areas. To generate data, the study used focus group discussions, Participatory Learning and Action (PLA) tools as part of Participatory Action Research (PAR), digital documentaries, as well as academic teachers’ rich descriptions of the rationale for the design and delivery techniques of their modules by means of focus group interviews, as well as curriculum review documents. The purpose of Action Research (AR) in this study was to enable change by way of advancing a self-consciousness, envisaged to yield some action based on the enablements or constraints identified by the participants involved. Archer’s (1995, 1996) analytical dualism was used as the analytical framework to identify the interplay of structural, cultural and agential mechanisms shaping the emergence of, and practices associated with students’ experiences of the science curriculum and academic teachers’ observations of these experiences. Bernstein’s pedagogic device was also used to explain the options that academic teachers have to shape the curriculum, a curriculum that would reflect the experiences of the heterogeneity of the student cohort when designing their course guides, for example. The analysis thus used Archer’s (1995, 1996) Morphogenesis/Morphostasis framework through which change or non-change can be observed over time. The work of Bhaskar (1975, 1979) was important in this regard because it allows us to separate what we see, experience and understand (in the transitive world) from what is independent of our thoughts and experiences (the intransitive world) when conducting scientific enquiry, so that we are able to deduce the ‘real’ factors that enable and constrain the events and experiences being studied. Since there are multiple mechanisms operative that can act to include or exclude students in Science classrooms, particularly those who come from lower class, including those who come from rural areas, this study focuses on curriculum as one mechanism that can be at play in the problem of exclusion. In this study, I argue, the University and its structures like curriculum are not neutral but are historical, cultural, political and social, which is why persistent apartheid legacy and coloniality were seen as playing a role in how the curriculum is designed and thus enacted. This is the reason, a decolonial gaze was adopted in order to engage with social justice issues and in the process tease out the social relations of knowledge practices. A decolonial gaze provided a way to re-describe the structuring of the curriculum and the contradictions it sets up for black students, particularly those who come from lower class backgrounds, including those from rural areas. Findings reveal that the way in which the science curriculum (and/or teaching and learning) is structured, and thus enacted, tends to favour certain worldviews to the exclusion of others. Also, findings show that when students are presented with knowledge that seems completely separate from them, their identities, their heritage, their backgrounds and value systems, accessing that knowledge can seem inordinately difficult. Consequently, students from rural contexts are often alienated, because the “world” they bring and know is often not considered part of the starting point, neither is it seen as relevant when teaching the science curriculum. There is therefore a clear need to bring something ‘from home’ into our teaching as a means of reassuring students that all is not foreign and that what they already know is valuable.
- Full Text:
- Date Issued: 2020
Passphrase and keystroke dynamics authentication: security and usability
- Authors: Bhana, Bhaveer
- Date: 2020
- Subjects: Computer security -- Management , Computers -- Access control -- Codewords , Computers -- Access control -- Keystroke timing authentication , Entropy (Information theory)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146663 , vital:38546
- Description: It was found that employees spend a total 2.25 days within a 60 day period on password related activities. Another study found that over 85 days an average user will create 25 accounts with an average of 6.5 unique passwords. These numbers are expected to increase over time as more systems become available. In addition, the use of 6.5 unique passwords highlight that passwords are being reused which creates security concerns as multiple systems will be accessible by an unauthorised party if one of these passwords is leaked. Current user authentication solutions either increase security or usability. When security increases, usability decreases, or vice versa. To add to this, stringent security protocols encourage unsecure behaviours by the user such as writing the password down on a piece of paper to remember it. It was found that passphrases require less cognitive effort than passwords and because passphrases are stronger than passwords, they don’t need to be changed as frequently as passwords. This study aimed to assess a two-tier user authentication solution that increases security and usability. The proposed solution uses passphrases in conjunction with keystroke dynamics to address this research problem. The design science research approach was used to guide this study. The study’s theoretical foundation includes three theories. The Shannon entropy formula was used to calculate the strength of passwords, passphrases and keystroke dynamics. The chunking theory assisted in assessing password and passphrase memorisation issues and the keystroke-level model was used to assess password and passphrase typing issues. Two primary data collection methods were used to evaluate the findings and to ensure that gaps in the research were filled. A login assessment experiment collected data on user authentication and user-system interaction for passwords and passphrases. Plus, an expert review was conducted to verify findings and assess the research artefact in the form of a model. The model can be used to assist with the implementation of a two-tier user authentication solution which involves passphrases and keystroke dynamics. There are a number of components that need to be considered to realise the benefits of this solution and ensure successful implementation.
- Full Text:
- Date Issued: 2020
- Authors: Bhana, Bhaveer
- Date: 2020
- Subjects: Computer security -- Management , Computers -- Access control -- Codewords , Computers -- Access control -- Keystroke timing authentication , Entropy (Information theory)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146663 , vital:38546
- Description: It was found that employees spend a total 2.25 days within a 60 day period on password related activities. Another study found that over 85 days an average user will create 25 accounts with an average of 6.5 unique passwords. These numbers are expected to increase over time as more systems become available. In addition, the use of 6.5 unique passwords highlight that passwords are being reused which creates security concerns as multiple systems will be accessible by an unauthorised party if one of these passwords is leaked. Current user authentication solutions either increase security or usability. When security increases, usability decreases, or vice versa. To add to this, stringent security protocols encourage unsecure behaviours by the user such as writing the password down on a piece of paper to remember it. It was found that passphrases require less cognitive effort than passwords and because passphrases are stronger than passwords, they don’t need to be changed as frequently as passwords. This study aimed to assess a two-tier user authentication solution that increases security and usability. The proposed solution uses passphrases in conjunction with keystroke dynamics to address this research problem. The design science research approach was used to guide this study. The study’s theoretical foundation includes three theories. The Shannon entropy formula was used to calculate the strength of passwords, passphrases and keystroke dynamics. The chunking theory assisted in assessing password and passphrase memorisation issues and the keystroke-level model was used to assess password and passphrase typing issues. Two primary data collection methods were used to evaluate the findings and to ensure that gaps in the research were filled. A login assessment experiment collected data on user authentication and user-system interaction for passwords and passphrases. Plus, an expert review was conducted to verify findings and assess the research artefact in the form of a model. The model can be used to assist with the implementation of a two-tier user authentication solution which involves passphrases and keystroke dynamics. There are a number of components that need to be considered to realise the benefits of this solution and ensure successful implementation.
- Full Text:
- Date Issued: 2020
Patterns and Pattern Languages for Mobile Augmented Reality
- Authors: Munro, Donald
- Date: 2020
- Subjects: Augmented reality , Educational technology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/48510 , vital:40883
- Description: Mixed Reality is a relatively new field in computer science which uses technology as a medium to provide modified or enhanced views of reality or to virtually generate a new reality. Augmented Reality is a branch of Mixed Reality which blends the real-world as viewed through a computer interface with virtual objects generated by a computer. The 21st century commodification of mobile devices with multi-core Central Processing Units, Graphics Processing Units, high definition displays and multiple sensors controlled by capable Operating Systems such as Android and iOS means that Mobile Augmented Reality applications have become increasingly feasible. Mobile Augmented Reality is a multi-disciplinary field requiring a synthesis of many technologies such as computer graphics, computer vision, machine learning and mobile device programming while also requiring theoretical knowledge of diverse fields such as Linear Algebra, Projective and Differential Geometry, Probability and Optimisation. This multi-disciplinary nature has led to a fragmentation of knowledge into various specialisations, making it difficult to integrate different solution components into a coherent architecture. Software design patterns provide a solution space of tried and tested best practices for a specified problem within a given context. The solution space is non-prescriptive and is described in terms of relationships between roles that can be assigned to software components. Architectural patterns are used to specify high level designs of complete systems, as opposed to domain or tactical level patterns that address specific lower level problem areas. Pattern Languages comprise multiple software patterns combining in multiple possible sequences to form a language with the individual patterns forming the language vocabulary while the valid sequences through the patterns define the grammar. Pattern Languages provide flexible generalised solutions within a particular domain that can be customised to solve problems of differing characteristics and levels of iii complexity within the domain. The specification of one or more Pattern Languages tailored to the Mobile Augmented Reality domain can therefore provide a generalised guide for the design and architecture of Mobile Augmented Reality applications from an architectural level down to the ”nuts-and-bolts” implementation level. While there is a large body of research into the technical specialisations pertaining to Mobile Augmented Reality, there is a dearth of up-to-date literature covering Mobile Augmented Reality design. This thesis fills this vacuum by: 1. Providing architectural patterns that provide the spine on which the design of Mobile Augmented Reality artefacts can be based; 2. Documenting existing patterns within the context of Mobile Augmented Reality; 3. Identifying new patterns specific to Mobile Augmented Reality; and 4. Combining the patterns into Pattern Languages for Detection & Tracking, Rendering & Interaction and Data Access for Mobile Augmented Reality. The resulting Pattern Languages support design at multiple levels of complexity from an object-oriented framework down to specific one-off Augmented Reality applications. The practical contribution of this thesis is the specification of architectural patterns and Pattern Language that provide a unified design approach for both the overall architecture and the detailed design of Mobile Augmented Reality artefacts. The theoretical contribution is a design theory for Mobile Augmented Reality gleaned from the extraction of patterns and creation of a pattern language or languages.
- Full Text:
- Date Issued: 2020
- Authors: Munro, Donald
- Date: 2020
- Subjects: Augmented reality , Educational technology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/48510 , vital:40883
- Description: Mixed Reality is a relatively new field in computer science which uses technology as a medium to provide modified or enhanced views of reality or to virtually generate a new reality. Augmented Reality is a branch of Mixed Reality which blends the real-world as viewed through a computer interface with virtual objects generated by a computer. The 21st century commodification of mobile devices with multi-core Central Processing Units, Graphics Processing Units, high definition displays and multiple sensors controlled by capable Operating Systems such as Android and iOS means that Mobile Augmented Reality applications have become increasingly feasible. Mobile Augmented Reality is a multi-disciplinary field requiring a synthesis of many technologies such as computer graphics, computer vision, machine learning and mobile device programming while also requiring theoretical knowledge of diverse fields such as Linear Algebra, Projective and Differential Geometry, Probability and Optimisation. This multi-disciplinary nature has led to a fragmentation of knowledge into various specialisations, making it difficult to integrate different solution components into a coherent architecture. Software design patterns provide a solution space of tried and tested best practices for a specified problem within a given context. The solution space is non-prescriptive and is described in terms of relationships between roles that can be assigned to software components. Architectural patterns are used to specify high level designs of complete systems, as opposed to domain or tactical level patterns that address specific lower level problem areas. Pattern Languages comprise multiple software patterns combining in multiple possible sequences to form a language with the individual patterns forming the language vocabulary while the valid sequences through the patterns define the grammar. Pattern Languages provide flexible generalised solutions within a particular domain that can be customised to solve problems of differing characteristics and levels of iii complexity within the domain. The specification of one or more Pattern Languages tailored to the Mobile Augmented Reality domain can therefore provide a generalised guide for the design and architecture of Mobile Augmented Reality applications from an architectural level down to the ”nuts-and-bolts” implementation level. While there is a large body of research into the technical specialisations pertaining to Mobile Augmented Reality, there is a dearth of up-to-date literature covering Mobile Augmented Reality design. This thesis fills this vacuum by: 1. Providing architectural patterns that provide the spine on which the design of Mobile Augmented Reality artefacts can be based; 2. Documenting existing patterns within the context of Mobile Augmented Reality; 3. Identifying new patterns specific to Mobile Augmented Reality; and 4. Combining the patterns into Pattern Languages for Detection & Tracking, Rendering & Interaction and Data Access for Mobile Augmented Reality. The resulting Pattern Languages support design at multiple levels of complexity from an object-oriented framework down to specific one-off Augmented Reality applications. The practical contribution of this thesis is the specification of architectural patterns and Pattern Language that provide a unified design approach for both the overall architecture and the detailed design of Mobile Augmented Reality artefacts. The theoretical contribution is a design theory for Mobile Augmented Reality gleaned from the extraction of patterns and creation of a pattern language or languages.
- Full Text:
- Date Issued: 2020
Performance, functionalism and form in Ịzọn oral poety
- Authors: Armstrong, Imomotimi
- Date: 2020
- Subjects: Ijo (African people , Ijo language , Folk poetry, Ijo , Folk poetry -- Nigeria
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/140641 , vital:37906
- Description: Since the publication of Ruth Finnegan’s influential Oral Literature in Africa, way back in 1970, scholars have been paying earnest attention to oral traditions on the African continent. That seminal book pointed out to Africanist scholars the need to urgently collect and document the oral literatures of their various ethnic groups before they die out. However, it is the verbal arts of the major ethnic groups on the continent that very often benefit from this collection and documentation, as it were. Therefore, this study sought to examine the oral poetry of the Ịzọn, a minority ethnic nationality, located in the oil-rich Niger Delta region of Nigeria. The study employed unstructured interviews and participant observations to collect the data for the research. The transcribed and translated data was examined through three eclectic theories to the study of folklore: Russian formalism, performance and functionalism. The study found out that Ịzọn oral poetry is a combination of songs and one person’s praise chants. Moreover, it revealed that praise chanting is a recent practice amongst the Ịzọn that was introduced into Ịzọnland by Chief Adolphus Munamuna from the Yoruba of southwestern Nigeria. Furthermore, the study established that oral poetry plays important roles amongst the people. Besides, it ascertained that the performance of some sub-categories of the poetry is highly dramatic and theatrical. It also discovered that stylistic techniques such as formula, parallelism, proverb, ideophone, praise title, metaphor, repetition, alliteration, assonance, vowel lengthening, amongst others, give the poetry the quality of “literariness.” In addition, the study found out that the poetry, like oral poetry in other ethnic groups, demonstrates the three qualities of change, adaptability and survival. The study has contributed to existing scholarship on African oral traditions in the sense of collecting, documenting and generating awareness on Ịzọn oral poetry, most importantly pointing out the existence of praise chanting amongst a people who had no such culture and the conditions that gave rise to that practice.
- Full Text:
- Date Issued: 2020
- Authors: Armstrong, Imomotimi
- Date: 2020
- Subjects: Ijo (African people , Ijo language , Folk poetry, Ijo , Folk poetry -- Nigeria
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/140641 , vital:37906
- Description: Since the publication of Ruth Finnegan’s influential Oral Literature in Africa, way back in 1970, scholars have been paying earnest attention to oral traditions on the African continent. That seminal book pointed out to Africanist scholars the need to urgently collect and document the oral literatures of their various ethnic groups before they die out. However, it is the verbal arts of the major ethnic groups on the continent that very often benefit from this collection and documentation, as it were. Therefore, this study sought to examine the oral poetry of the Ịzọn, a minority ethnic nationality, located in the oil-rich Niger Delta region of Nigeria. The study employed unstructured interviews and participant observations to collect the data for the research. The transcribed and translated data was examined through three eclectic theories to the study of folklore: Russian formalism, performance and functionalism. The study found out that Ịzọn oral poetry is a combination of songs and one person’s praise chants. Moreover, it revealed that praise chanting is a recent practice amongst the Ịzọn that was introduced into Ịzọnland by Chief Adolphus Munamuna from the Yoruba of southwestern Nigeria. Furthermore, the study established that oral poetry plays important roles amongst the people. Besides, it ascertained that the performance of some sub-categories of the poetry is highly dramatic and theatrical. It also discovered that stylistic techniques such as formula, parallelism, proverb, ideophone, praise title, metaphor, repetition, alliteration, assonance, vowel lengthening, amongst others, give the poetry the quality of “literariness.” In addition, the study found out that the poetry, like oral poetry in other ethnic groups, demonstrates the three qualities of change, adaptability and survival. The study has contributed to existing scholarship on African oral traditions in the sense of collecting, documenting and generating awareness on Ịzọn oral poetry, most importantly pointing out the existence of praise chanting amongst a people who had no such culture and the conditions that gave rise to that practice.
- Full Text:
- Date Issued: 2020
Phytoplankton of the Southern Agulhas Large Marine Ecosystem (sACLME)
- Authors: Sonnekus, Martinus Jakobus
- Date: 2020
- Subjects: Botanical chemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/47646 , vital:40261
- Description: The southern Agulhas Large Marine Ecosystem (sACLME) consists of the greater Agulhas Current system, including the areas influenced by the Agulhas Current, the Agulhas Shelf, Agulhas Bank, Agulhas Retroflection as well as the Agulhas Return Current. Four biogeographical regions were identified within the sACLME and the composition of the phytoplankton communities and the associated physico-chemical variables in each were investigated. Water temperature and nitrate concentration were found to be the main drivers of the sACLME phytoplankton community. A total of 215 phytoplankton taxa were identified that were separated into two groups: the Agulhas Current group and the Southwest Indian Ocean Ridge group. The structure of the phytoplankton community was consistently homogeneous throughout the sACLME. Nutrient concentrations of the water varied, but nitrate was the most abundant source of nitrogen, especially in regions that were subjected to the upwelling of cold nutrient-rich water. The phytoplankton communities were significantly influenced by the availability and stoichiometry of the macronutrients nitrogen; phosphorus and silicon. The low mean N:P ratio of 5.5 is an indication that the waters of the sACLME are generally nitrogen limited, as is typical of oceanic systems. There is a change in phytoplankton cell size and functional groups within in the various water masses that are specific to certain biogeographical regions within the Agulhas Current system. It is clear that frontal systems may form barriers between phytoplankton communities.
- Full Text:
- Date Issued: 2020
- Authors: Sonnekus, Martinus Jakobus
- Date: 2020
- Subjects: Botanical chemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/47646 , vital:40261
- Description: The southern Agulhas Large Marine Ecosystem (sACLME) consists of the greater Agulhas Current system, including the areas influenced by the Agulhas Current, the Agulhas Shelf, Agulhas Bank, Agulhas Retroflection as well as the Agulhas Return Current. Four biogeographical regions were identified within the sACLME and the composition of the phytoplankton communities and the associated physico-chemical variables in each were investigated. Water temperature and nitrate concentration were found to be the main drivers of the sACLME phytoplankton community. A total of 215 phytoplankton taxa were identified that were separated into two groups: the Agulhas Current group and the Southwest Indian Ocean Ridge group. The structure of the phytoplankton community was consistently homogeneous throughout the sACLME. Nutrient concentrations of the water varied, but nitrate was the most abundant source of nitrogen, especially in regions that were subjected to the upwelling of cold nutrient-rich water. The phytoplankton communities were significantly influenced by the availability and stoichiometry of the macronutrients nitrogen; phosphorus and silicon. The low mean N:P ratio of 5.5 is an indication that the waters of the sACLME are generally nitrogen limited, as is typical of oceanic systems. There is a change in phytoplankton cell size and functional groups within in the various water masses that are specific to certain biogeographical regions within the Agulhas Current system. It is clear that frontal systems may form barriers between phytoplankton communities.
- Full Text:
- Date Issued: 2020
Post release evaluation of the distribution and efficacy of Eccritotarsus catarinensis and Eccritotarsus eichhorniae on Pontederia crassipes in South Africa
- Authors: Maseko, Zolile
- Date: 2020
- Subjects: Water hyacinth -- Biological control -- South Africa , Weeds -- Biological control -- South Africa , Miridae -- South Africa , Insects as biological pest control agents -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/143046 , vital:38196
- Description: Biological control involves the release of new species into the environment and therefore, needs to be carefully monitored through post-release assessments which have been largely neglected in the science. Post-release evaluations of biological control programmes reveal whether the control agent has established and if it impacts weed demography, while cost-benefit analyses require a different set of data that show the magnitude on return on investment. The biological control effort on Pontederia crassipes in South Africa uses, amongst others, two species of mirid, Eccritotarsus catarinensis and E. eichhorniae. Initially, they were released as a single species, but were recently divided using molecular techniques. Eccritotarsus catarinensis was released in 1999, and E. eichhorniae in 2007. After many releases over two decades, there was need to assess where each species was established in the country. Molecular techniques proved to be valuable in identifying the two species as they are morphologically indistinguishable in the field. Therefore, molecular techniques should be routinely used for screening biocontrol agents, whether new or as re-introductions. Annual surveys of the mirid release sites around South Africa were undertaken between 2016 and 2019. At each site both insect and plant parameters were measured. Only E. catarinensis is established in the field in South Africa despite the multiple releases of E. eichhorniae at over 70 sites across the country, and E. catarinensis has established at only 22 of the 45 release sites accessed during this study. This thesis tested climate, interaction with other agents already on P. crassipes, and direct competition between the two mirid species as reasons for the lack of establishment of E. eichhorniae. The results of the country-wide surveys showed that climate and water trophic status were the major determinants in the establishment of E. catarinensis. Most of the establishment was recorded in the warmer regions of the country, however, a few populations of the mirid also established in cooler areas, thus demonstrating a degree of thermal plasticity, and possible microclimates as the mirids persisted at sites shaded by riparian vegetation. Stochastic events such as active herbicide campaigns, winter frosts, droughts and floods were responsible for the absence of the mirid at some sites. At some of the eutrophic sites, despite the abundance of E. catarinensis, plants still proliferated as the water trophic status facilitated plant growth, thus, plants were able to compensate for the damage inflicted by the mirid. A more intensive, monthly, post-release evaluation was conducted on the Kubusi River, Eastern Cape Province between 2016 and 2019. This is regarded as one of the cooler water hyacinth sites. Populations of biological control agents at this site fluctuated seasonally. At this site, cold winters caused frosting of the leaves of P. crassipes with the exception of plants growing under overhanging vegetation that provided a refuge for the mirid. But, cool temperatures in the winter months (May to August) severely reduced the populations of E. catarinensis that required a long recovery phase in spring. The consequence of this was that the plants grew unchecked from the onset of the growing season forming dense mats. Of the four agents at the Kubusi River site, Eccritotarsus catarinensis recovered slowest after winter, with lag phases ranging from two months to several months of the three-year period. The release of a suite of agents has implications on the agents themselves, where interactions between the agents can be important. Interactions between pairs and even multiple agents can have implications for biocontrol, where agents are either complimentary or interfere with each other. In this case, because E. catarinensis recovered the slowest of the four agents at the site, plants were of a poor quality by mid-summer resulting in low mirid populations. Competition in weed biological control could be expected to be strongest between pairs of agents that share the same niche, and this could be the reason why E. eichhorniae failed to establish at sites where E. catarinensis had already been established for several years. When the two mirids were combined in manipulated trials in a polytunnel, populations were lower compared to when the two mirids occurred separately. Under warm conditions, it is likely that E. eichhorniae would be the superior agent compared to E. catarinensis. The evaluations discussed in this thesis highlighted gaps in agent release methodology in multispecies settings, as well as the need for strategic augmentation pre- and post-winter. It is important to release agents that will complement each other rather than compete, therefore, when releasing agents in a multispecies setting, niche differentiation needs to be considered. Here it is concluded that the best practice for dealing with the mirids is that they should be released individually, and at sites that have no other biological control agents in order to ultimately assess their efficacy. Landscape level, long-term monitoring of biological control programmes shows the impact of the control programme at a broader scale and, are far more informative than short-term studies and at fewer sites. Long-term post-release evaluations should be mandatory in biological control programmes. Furthermore, these assessments will help develop new strategies or improve on existing ones, thus achieve greater success in control.
- Full Text:
- Date Issued: 2020
- Authors: Maseko, Zolile
- Date: 2020
- Subjects: Water hyacinth -- Biological control -- South Africa , Weeds -- Biological control -- South Africa , Miridae -- South Africa , Insects as biological pest control agents -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/143046 , vital:38196
- Description: Biological control involves the release of new species into the environment and therefore, needs to be carefully monitored through post-release assessments which have been largely neglected in the science. Post-release evaluations of biological control programmes reveal whether the control agent has established and if it impacts weed demography, while cost-benefit analyses require a different set of data that show the magnitude on return on investment. The biological control effort on Pontederia crassipes in South Africa uses, amongst others, two species of mirid, Eccritotarsus catarinensis and E. eichhorniae. Initially, they were released as a single species, but were recently divided using molecular techniques. Eccritotarsus catarinensis was released in 1999, and E. eichhorniae in 2007. After many releases over two decades, there was need to assess where each species was established in the country. Molecular techniques proved to be valuable in identifying the two species as they are morphologically indistinguishable in the field. Therefore, molecular techniques should be routinely used for screening biocontrol agents, whether new or as re-introductions. Annual surveys of the mirid release sites around South Africa were undertaken between 2016 and 2019. At each site both insect and plant parameters were measured. Only E. catarinensis is established in the field in South Africa despite the multiple releases of E. eichhorniae at over 70 sites across the country, and E. catarinensis has established at only 22 of the 45 release sites accessed during this study. This thesis tested climate, interaction with other agents already on P. crassipes, and direct competition between the two mirid species as reasons for the lack of establishment of E. eichhorniae. The results of the country-wide surveys showed that climate and water trophic status were the major determinants in the establishment of E. catarinensis. Most of the establishment was recorded in the warmer regions of the country, however, a few populations of the mirid also established in cooler areas, thus demonstrating a degree of thermal plasticity, and possible microclimates as the mirids persisted at sites shaded by riparian vegetation. Stochastic events such as active herbicide campaigns, winter frosts, droughts and floods were responsible for the absence of the mirid at some sites. At some of the eutrophic sites, despite the abundance of E. catarinensis, plants still proliferated as the water trophic status facilitated plant growth, thus, plants were able to compensate for the damage inflicted by the mirid. A more intensive, monthly, post-release evaluation was conducted on the Kubusi River, Eastern Cape Province between 2016 and 2019. This is regarded as one of the cooler water hyacinth sites. Populations of biological control agents at this site fluctuated seasonally. At this site, cold winters caused frosting of the leaves of P. crassipes with the exception of plants growing under overhanging vegetation that provided a refuge for the mirid. But, cool temperatures in the winter months (May to August) severely reduced the populations of E. catarinensis that required a long recovery phase in spring. The consequence of this was that the plants grew unchecked from the onset of the growing season forming dense mats. Of the four agents at the Kubusi River site, Eccritotarsus catarinensis recovered slowest after winter, with lag phases ranging from two months to several months of the three-year period. The release of a suite of agents has implications on the agents themselves, where interactions between the agents can be important. Interactions between pairs and even multiple agents can have implications for biocontrol, where agents are either complimentary or interfere with each other. In this case, because E. catarinensis recovered the slowest of the four agents at the site, plants were of a poor quality by mid-summer resulting in low mirid populations. Competition in weed biological control could be expected to be strongest between pairs of agents that share the same niche, and this could be the reason why E. eichhorniae failed to establish at sites where E. catarinensis had already been established for several years. When the two mirids were combined in manipulated trials in a polytunnel, populations were lower compared to when the two mirids occurred separately. Under warm conditions, it is likely that E. eichhorniae would be the superior agent compared to E. catarinensis. The evaluations discussed in this thesis highlighted gaps in agent release methodology in multispecies settings, as well as the need for strategic augmentation pre- and post-winter. It is important to release agents that will complement each other rather than compete, therefore, when releasing agents in a multispecies setting, niche differentiation needs to be considered. Here it is concluded that the best practice for dealing with the mirids is that they should be released individually, and at sites that have no other biological control agents in order to ultimately assess their efficacy. Landscape level, long-term monitoring of biological control programmes shows the impact of the control programme at a broader scale and, are far more informative than short-term studies and at fewer sites. Long-term post-release evaluations should be mandatory in biological control programmes. Furthermore, these assessments will help develop new strategies or improve on existing ones, thus achieve greater success in control.
- Full Text:
- Date Issued: 2020
Post-apartheid nostalgia and the future of the black visual archive
- Nsele, Zamansele Nsikakazi Busisiwe
- Authors: Nsele, Zamansele Nsikakazi Busisiwe
- Date: 2020
- Subjects: Nostalgia in art , Memory in art , Africa -- In art , Africans in art , Fanon, Frantz, 1925-1961. Peau noire, masques blancs. English , South Africa -- In art , Black people in art
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167177 , vital:41444
- Description: The implications of nostalgia often strike a discordant note in post-apartheid discourse and this has opened up critical possibilities for research scholarship. For instance, Jacob Dlamini’s memoir Native Nostalgia entered the discursive fray in 2009, and it was subsequently followed by Derek Hook’s psychoanalytical approach in (Post) apartheid Conditions: Psychoanalysis and Social Formation in 2014. Notably, there is not yet a sustained and intensive research focus that has been conducted on post-apartheid forms of nostalgia within the discipline of art history and visual culture. I present this dissertation as a response to this gap. This thesis identifies mainly two competing nostalgias in post-apartheid South Africa. Through the analysis of selected artwork and media imagery, this dissertation critiques the connections of these nostalgias to the representation of the black figure in post-apartheid visual culture and the implications thereof. I argue that nostalgias for an apartheid-colonial-imperialist past operate through erasure and in the sanitisation of memory and as a result they render suffering indiscernible or in a sadomasochistic way consumes suffering as enjoyable. This thesis simultaneously critiques art work and visual representation that responds to South Africa’s nostalgia for the future: a restorative nostalgia that has emerged in the form of “rainbow nationalism”. This is a form of nostalgia that is underpinned by a dogged commitment to triumphalism and as a result erases the ongoing scenes of abjection. I use nostalgia and Afropessimism as analytical frameworks to argue that both real and visual representational forces work in tandem to restrain the future and this, I suggest is fulfilled by the transference of the black body from one state of unfreedom to next, resonating with a cyclical pattern. Frantz Fanon’s (1967) Black Skin White Mask forms the conceptual bedrock of my study, particularly his visual layout of “negrophobogenesis” and colonial temporality, which he describes as a “hellish cycle” or as an “infernal cycle” wherein the past overwhelms the present and ideas of the future.
- Full Text:
- Date Issued: 2020
- Authors: Nsele, Zamansele Nsikakazi Busisiwe
- Date: 2020
- Subjects: Nostalgia in art , Memory in art , Africa -- In art , Africans in art , Fanon, Frantz, 1925-1961. Peau noire, masques blancs. English , South Africa -- In art , Black people in art
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167177 , vital:41444
- Description: The implications of nostalgia often strike a discordant note in post-apartheid discourse and this has opened up critical possibilities for research scholarship. For instance, Jacob Dlamini’s memoir Native Nostalgia entered the discursive fray in 2009, and it was subsequently followed by Derek Hook’s psychoanalytical approach in (Post) apartheid Conditions: Psychoanalysis and Social Formation in 2014. Notably, there is not yet a sustained and intensive research focus that has been conducted on post-apartheid forms of nostalgia within the discipline of art history and visual culture. I present this dissertation as a response to this gap. This thesis identifies mainly two competing nostalgias in post-apartheid South Africa. Through the analysis of selected artwork and media imagery, this dissertation critiques the connections of these nostalgias to the representation of the black figure in post-apartheid visual culture and the implications thereof. I argue that nostalgias for an apartheid-colonial-imperialist past operate through erasure and in the sanitisation of memory and as a result they render suffering indiscernible or in a sadomasochistic way consumes suffering as enjoyable. This thesis simultaneously critiques art work and visual representation that responds to South Africa’s nostalgia for the future: a restorative nostalgia that has emerged in the form of “rainbow nationalism”. This is a form of nostalgia that is underpinned by a dogged commitment to triumphalism and as a result erases the ongoing scenes of abjection. I use nostalgia and Afropessimism as analytical frameworks to argue that both real and visual representational forces work in tandem to restrain the future and this, I suggest is fulfilled by the transference of the black body from one state of unfreedom to next, resonating with a cyclical pattern. Frantz Fanon’s (1967) Black Skin White Mask forms the conceptual bedrock of my study, particularly his visual layout of “negrophobogenesis” and colonial temporality, which he describes as a “hellish cycle” or as an “infernal cycle” wherein the past overwhelms the present and ideas of the future.
- Full Text:
- Date Issued: 2020
Promoting leader intergrity through the human resource management chain
- Authors: De Villiers, Marie Bridget
- Date: 2020
- Subjects: Leadersship --Moral and ethical Aspects -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/49791 , vital:41801
- Description: Ethical breaches in the public and private sector in South Africa are prevalent and the effects thereof pervasive on the economy and within broader society. These ethical breaches include corruption, bribery, and the mismanagement of resources and may be attributed to poor decision-making on the part of organisational leaders. The complexity of the circumstances in which organisations operate in the 21st century requires that leaders effectively navigate moral dilemmas while considering the broad range of interests represented by many organisational stakeholders. Leaders need to act in a manner that is ethically sound to avoid the negative consequences associated with unethical organisational conduct, including a loss of profit, credibility and reputation. Ethical leadership is central to moral organisational governance, as compliance with rules and regulations alone is ineffective in building and sustaining an ethical organisation. Literature points to the centrality of leader integrity to the notion of ethical leadership and that an ethical organisational culture is sustained by leaders who possess integrity. In promoting leader integrity studies highlight management interventions and organisational success factors that promote an ethical organisation. Within the context of this study these management interventions and success factors were identified as promoting leader integrity. Further, the literature identified the important role of leaders in supporting these interventions and creating the conditions necessary to foster the success factors. These management interventions are offered through and the success factors are linked to the human resource management value chain. The main aim of this study was to explore the promotion of leader integrity through the human resource management value chain in South African organisations. The main aim of the study led to the development of several theoretical and empirical sub-objectives that were addressed.
- Full Text:
- Date Issued: 2020
- Authors: De Villiers, Marie Bridget
- Date: 2020
- Subjects: Leadersship --Moral and ethical Aspects -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/49791 , vital:41801
- Description: Ethical breaches in the public and private sector in South Africa are prevalent and the effects thereof pervasive on the economy and within broader society. These ethical breaches include corruption, bribery, and the mismanagement of resources and may be attributed to poor decision-making on the part of organisational leaders. The complexity of the circumstances in which organisations operate in the 21st century requires that leaders effectively navigate moral dilemmas while considering the broad range of interests represented by many organisational stakeholders. Leaders need to act in a manner that is ethically sound to avoid the negative consequences associated with unethical organisational conduct, including a loss of profit, credibility and reputation. Ethical leadership is central to moral organisational governance, as compliance with rules and regulations alone is ineffective in building and sustaining an ethical organisation. Literature points to the centrality of leader integrity to the notion of ethical leadership and that an ethical organisational culture is sustained by leaders who possess integrity. In promoting leader integrity studies highlight management interventions and organisational success factors that promote an ethical organisation. Within the context of this study these management interventions and success factors were identified as promoting leader integrity. Further, the literature identified the important role of leaders in supporting these interventions and creating the conditions necessary to foster the success factors. These management interventions are offered through and the success factors are linked to the human resource management value chain. The main aim of this study was to explore the promotion of leader integrity through the human resource management value chain in South African organisations. The main aim of the study led to the development of several theoretical and empirical sub-objectives that were addressed.
- Full Text:
- Date Issued: 2020
Psychological and emotional effects of repeated exposure to violent crimes on victims residing in a high crime community in Nelson Mandela Metropolitan in the Eastern Cape
- Authors: De Klerk, Ulricha
- Date: 2020
- Subjects: Post-traumatic stress disorder
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/46413 , vital:39582
- Description: Traumatic Stress Disorder (PTSD). While the literature provides detailed and comprehensive approaches and counselling modalities to working with clients who experience traumatic events, there is not much evidence on the experiences of individuals who reside in high crime communities. It follows, that the psychological and emotional experiences, as well as needs of such individuals may present with specific requirements from the therapeutic alliance. This study aimed to explore the psychological and emotional effects of repeated exposure to high crime and violence and the implications this posed to traumatic experiences. The study further aimed to develop a set of guidelines that can be drawn upon when working therapeutically with clients who reside in high crime communities. The study draws on a qualitative methodology and 17 participants were interviewed. The transcripts were analysed using thematic analysis and five themes were identified, relevant to the aims and objectives that were set. The findings suggest that the psychological and emotional experiences of individuals who reside in high crime communities, is experienced at a more heightened and prolonged period, thus making the psychotherapeutic intervention employed, more specific. To this effect, the guidelines developed provide specific strategies and approaches thatwere developed based on the themes identified and verified by a panel of psychological experts. The study contributes to the field of trauma, counselling and violence, in that it focuses on an area of trauma that has not been adequately focused on withinthe South African context, as well as in global contexts.
- Full Text:
- Date Issued: 2020
- Authors: De Klerk, Ulricha
- Date: 2020
- Subjects: Post-traumatic stress disorder
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/46413 , vital:39582
- Description: Traumatic Stress Disorder (PTSD). While the literature provides detailed and comprehensive approaches and counselling modalities to working with clients who experience traumatic events, there is not much evidence on the experiences of individuals who reside in high crime communities. It follows, that the psychological and emotional experiences, as well as needs of such individuals may present with specific requirements from the therapeutic alliance. This study aimed to explore the psychological and emotional effects of repeated exposure to high crime and violence and the implications this posed to traumatic experiences. The study further aimed to develop a set of guidelines that can be drawn upon when working therapeutically with clients who reside in high crime communities. The study draws on a qualitative methodology and 17 participants were interviewed. The transcripts were analysed using thematic analysis and five themes were identified, relevant to the aims and objectives that were set. The findings suggest that the psychological and emotional experiences of individuals who reside in high crime communities, is experienced at a more heightened and prolonged period, thus making the psychotherapeutic intervention employed, more specific. To this effect, the guidelines developed provide specific strategies and approaches thatwere developed based on the themes identified and verified by a panel of psychological experts. The study contributes to the field of trauma, counselling and violence, in that it focuses on an area of trauma that has not been adequately focused on withinthe South African context, as well as in global contexts.
- Full Text:
- Date Issued: 2020
Quantifying ecosystem restoration recovery and restoration practice following the biological control of invasive alien macrophytes in Southern Africa
- Authors: Motitsoe, Samuel Nkopane
- Date: 2020
- Subjects: Salvinia molesta , Ceratophyllum demersum , Nymphaea mexicana , Invasive plants -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Restoration monitoring (Ecology) -- South Africa , Biolotical invasions -- Environmental aspects
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167519 , vital:41488
- Description: Invasive alien aquatic plants (IAAP) species are known to have deleterious effects on the freshwater ecosystems they invade. This includes both socio-economic and ecologically important ecosystem goods and services. Thus, IAAP species are declared a serious threat, second only to habitat modification for causing a loss of aquatic biodiversity. Three control methods have been widely applied to control IAAP species invasion globally; mechanical, chemical and biological control. Both mechanical and chemical control methods are considered short-term and expensive, whereas biological control methods are regarded an effective and long-term solution for IAAP species control at the landscape level. But, little is known of the ecological recovery following the biological control of IAAP species, with mechanical control known to have had mixed success and chemical control to have non-targeted effects on aquatic ecosystems, causing harm to wildlife and human well-being. Biological control practitioners measure the success of biological control based on: (1) the biological control agents’ establishment and the negative impacts they impose on the targeted weed; and (2) the weeds biomass reduction and an increase in native macrophytes species. Arguably, measures of biological control success have been subjective and variable across the globe. Although some field studies have demonstrated biological control success to have positive socio-economic returns, there is little literature on ecological benefits. Furthermore, there is limited understanding on ecosystem recovery and possible restoration efforts following the biological control IAAP species, as compared to alien weeds in terrestrial and riparian ecosystems. Thus, this thesis aimed to quantify the ecological recovery i.e. aquatic biodiversity, ecosystem processes and trophic interactions following the management of Salvinia molesta in freshwater ecosystems. The research employed a suite of Before-After Control-Impact mesocosm and field studies to investigate the response of aquatic microalgae, macroinvertebrates and their interactions (food web structure and function) during S. molesta infestation and after mechanical and biological control. The mesocosm experiment (Before invasion, During invasion & After control) showed that both aquatic microalgae and macroinvertebrate diversity indices were reliable biological indicators of S. molesta ecological impacts and recovery following control. The restored treatment (100% S. molesta cover + biological control agents), demonstrated complete aquatic microalgae and macroinvertebrate recovery following biological control, similar to the control treatment (open water), where the degraded/impacted treatment (100% S. molesta cover with no biological control agents) showed a drastic decline in aquatic biodiversity and a complete shift in aquatic biota assemblage structure. Thus, the biological control effort by Cyrtobagous salviniae, the biological control agent for S. molesta, assisted in the recovery of aquatic biota following successful biological control. The field study (four field sites, two sites controlled mechanically and two biologically) investigated water quality, aquatic biodiversity and community trophic interactions (aquatic food web) “before and after” S. molesta control. The study showed a drastic decline in aquatic biodiversity (with three sites showing no record of aquatic macroinvertebrates, thus no biotic interactions during infestation) and poor water quality due to the shade-effect (light barrier due to floating S. molesta mats on the water surface) during the “before” S. molesta control phase. However, following both mechanical and biological control (“after” S. molesta control phase), there was a significant shift in abiotic and biotic ecosystem characteristics as compared to the “before” S. molesta control phase. Thus, rapid ecosystem recovery was apparent as a result of aquatic microalgae and macroinvertebrates recolonisation. Sites showed a normal functioning ecosystem where improved water quality, increased biodiversity, productivity and trophic interactions, was indicative of the return of biologically and functionally important species which were lost during the “before” S. molesta phase. Although the clear water state showed positive outcomes at Westlake River, these were short lived when the system was dominated by a cosmopolitan submerged Ceratophyllum demersum, and later replaced by a floating-leaved emergent IAAP Nymphaea mexicana. Each state was responsible for a significant shift in both biotic and abiotic characteristics, affirming macrophyte abilities to influence aquatic environments structure and functions. Furthermore, this event showed a clear example of a secondary invasion. Thus, a holistic IAAP species management strategy is necessary to restore previously invaded ecosystems and prevent subsequent secondary invasion and ecosystem degradation. In conclusion, the S. molesta shade-effect like any other free-floating IAAP species, was identified as the main degrading factor and responsible for water quality reduction, loss of aquatic diversity and shift in aquatic biota assemblage structure. Following S. molesta removal (or shade-effect elimination), there was a positive response to aquatic ecosystem species abundance, richness, diversity and community structure. Therefore, in combination, aquatic biota recolonisation rate and increases in biological and functional diversity were instrumental in the recovery of ecosystem structure and functions, following the control of S. molesta. Echoing existing literature, this thesis recommends: (1) IAAP species management programmes (mechanical and/or biological control) should not only aim to control the weed but also focus on ecosystems recovery and possible restoration goals; (2) biological control should be used where appropriate to combat free-floating IAAP species in freshwater ecosystems, followed by active introduction of native macrophyte propagules since they are limited by anthropogenic activities; and (3) more freshwater case studies are needed to add to our understanding of IAAP species management and restoration effort incorporating long-term monitoring.
- Full Text:
- Date Issued: 2020
- Authors: Motitsoe, Samuel Nkopane
- Date: 2020
- Subjects: Salvinia molesta , Ceratophyllum demersum , Nymphaea mexicana , Invasive plants -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Restoration monitoring (Ecology) -- South Africa , Biolotical invasions -- Environmental aspects
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167519 , vital:41488
- Description: Invasive alien aquatic plants (IAAP) species are known to have deleterious effects on the freshwater ecosystems they invade. This includes both socio-economic and ecologically important ecosystem goods and services. Thus, IAAP species are declared a serious threat, second only to habitat modification for causing a loss of aquatic biodiversity. Three control methods have been widely applied to control IAAP species invasion globally; mechanical, chemical and biological control. Both mechanical and chemical control methods are considered short-term and expensive, whereas biological control methods are regarded an effective and long-term solution for IAAP species control at the landscape level. But, little is known of the ecological recovery following the biological control of IAAP species, with mechanical control known to have had mixed success and chemical control to have non-targeted effects on aquatic ecosystems, causing harm to wildlife and human well-being. Biological control practitioners measure the success of biological control based on: (1) the biological control agents’ establishment and the negative impacts they impose on the targeted weed; and (2) the weeds biomass reduction and an increase in native macrophytes species. Arguably, measures of biological control success have been subjective and variable across the globe. Although some field studies have demonstrated biological control success to have positive socio-economic returns, there is little literature on ecological benefits. Furthermore, there is limited understanding on ecosystem recovery and possible restoration efforts following the biological control IAAP species, as compared to alien weeds in terrestrial and riparian ecosystems. Thus, this thesis aimed to quantify the ecological recovery i.e. aquatic biodiversity, ecosystem processes and trophic interactions following the management of Salvinia molesta in freshwater ecosystems. The research employed a suite of Before-After Control-Impact mesocosm and field studies to investigate the response of aquatic microalgae, macroinvertebrates and their interactions (food web structure and function) during S. molesta infestation and after mechanical and biological control. The mesocosm experiment (Before invasion, During invasion & After control) showed that both aquatic microalgae and macroinvertebrate diversity indices were reliable biological indicators of S. molesta ecological impacts and recovery following control. The restored treatment (100% S. molesta cover + biological control agents), demonstrated complete aquatic microalgae and macroinvertebrate recovery following biological control, similar to the control treatment (open water), where the degraded/impacted treatment (100% S. molesta cover with no biological control agents) showed a drastic decline in aquatic biodiversity and a complete shift in aquatic biota assemblage structure. Thus, the biological control effort by Cyrtobagous salviniae, the biological control agent for S. molesta, assisted in the recovery of aquatic biota following successful biological control. The field study (four field sites, two sites controlled mechanically and two biologically) investigated water quality, aquatic biodiversity and community trophic interactions (aquatic food web) “before and after” S. molesta control. The study showed a drastic decline in aquatic biodiversity (with three sites showing no record of aquatic macroinvertebrates, thus no biotic interactions during infestation) and poor water quality due to the shade-effect (light barrier due to floating S. molesta mats on the water surface) during the “before” S. molesta control phase. However, following both mechanical and biological control (“after” S. molesta control phase), there was a significant shift in abiotic and biotic ecosystem characteristics as compared to the “before” S. molesta control phase. Thus, rapid ecosystem recovery was apparent as a result of aquatic microalgae and macroinvertebrates recolonisation. Sites showed a normal functioning ecosystem where improved water quality, increased biodiversity, productivity and trophic interactions, was indicative of the return of biologically and functionally important species which were lost during the “before” S. molesta phase. Although the clear water state showed positive outcomes at Westlake River, these were short lived when the system was dominated by a cosmopolitan submerged Ceratophyllum demersum, and later replaced by a floating-leaved emergent IAAP Nymphaea mexicana. Each state was responsible for a significant shift in both biotic and abiotic characteristics, affirming macrophyte abilities to influence aquatic environments structure and functions. Furthermore, this event showed a clear example of a secondary invasion. Thus, a holistic IAAP species management strategy is necessary to restore previously invaded ecosystems and prevent subsequent secondary invasion and ecosystem degradation. In conclusion, the S. molesta shade-effect like any other free-floating IAAP species, was identified as the main degrading factor and responsible for water quality reduction, loss of aquatic diversity and shift in aquatic biota assemblage structure. Following S. molesta removal (or shade-effect elimination), there was a positive response to aquatic ecosystem species abundance, richness, diversity and community structure. Therefore, in combination, aquatic biota recolonisation rate and increases in biological and functional diversity were instrumental in the recovery of ecosystem structure and functions, following the control of S. molesta. Echoing existing literature, this thesis recommends: (1) IAAP species management programmes (mechanical and/or biological control) should not only aim to control the weed but also focus on ecosystems recovery and possible restoration goals; (2) biological control should be used where appropriate to combat free-floating IAAP species in freshwater ecosystems, followed by active introduction of native macrophyte propagules since they are limited by anthropogenic activities; and (3) more freshwater case studies are needed to add to our understanding of IAAP species management and restoration effort incorporating long-term monitoring.
- Full Text:
- Date Issued: 2020
Reef fish associations with benthic habitats at a remote protected coral reef ecosystem in the Western Indian Ocean-Aldabra Atoll, Seychelles
- Authors: Haupt, Philip
- Date: 2020
- Subjects: Coral reef ecology -- Aldabra Islands (Seychelles) , Reef fishes -- Aldabra Islands (Seychelles) , Benthic animals -- Aldabra Islands (Seychelles)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/141629 , vital:37991
- Description: The aim of the thesis is to develop an understanding of the associations between reef fish and benthic habitats and assess the modifying effects of environmental processes on these relationships at Aldabra, a pristine atoll in the Western Indian Ocean (WIO). Conducting research in pristine, or reference coral reef ecosystem, removes the impact of direct anthropogenic disturbances and provides essential information on natural ecosystem structure and functioning. Three primary hypotheses were tested: 1) Environmental drivers such as depth and exposure to wave energy determine the spatial distribution of benthic habitats; 2) The reef fish assemblage structure is explained by habitat at multiple scales and modified by the effects of environmental drivers such as depth, wave energy and cyclical temporal drivers such as time and tides; 3) The reef fish assemblage at Aldabra represents a pristine reef fish assemblage, comprising high levels of herbivores and predators. The research focussed on the benthic habitat on the seaward reefs between the shoreline and 50 m depth. The first objective was to characterise the benthic habitats on Aldabra Atoll’s seaward reefs and map their spatial distributions using remotely sensed imagery and ground truthing data. The second was to assess the influence of depth and exposure to wave energy on the distribution of benthic habitats. The third was to identify the most suitable standardised method to survey the reef fish assemblage structure on Aldabra’s, and fourth to determine the effect of tide and time of day on the reef fish assemblage. The fifth objective was to establish the association between reef fish assemblage structure and benthic habitats and to test how species-size influenced the scale of habitat at which the associations were most apparent. Four categories of geomorphic reef zones (reef flats (19.2 km2), top of the forereef slope (7.8 km2), deep forereef slope (11.6 km2), and reef platform (14.3 km2)) were manually delineated following the visual outlines of reef features from satellite imagery. The six broad-scale and twelve fine-scale benthic habitats were mapped using a supervised maximum likelihood classification and the spatial coverage of each determined. The broad-scale habitats were 1) Epilithic algal matrix, 2) Hard and soft (coral, 3) Rubble, 4) Macroalgae, 5) Seagrass and 6) Sand. Similarly, twelve fine-scale benthic habitats were characterised and mapped, for example, Hard coral (19 %) including massive and submassive forms with Millepora and Rhytisma. The broad-scale benthic habitat map had an overall producer accuracy of 54 % and fine-scale habitat map 29 %, which was consistent with studies using similar habitat classification methods. The prevailing wave energy, depth and the directional orientation of coral reefs (aspect) significantly influenced the probability of occurrence of each of the broad-scale benthic habitats, and there was a shift in peak probability of occurrence of all habitat categories to a greater depth with an increase in wave energy. The strong relationship of benthic habitats with depth and wave energy suggests that the distributions of benthic habitats are likely to change with sea-level rise and increased intensity and frequency of storms in future. Overall, 338 fish species from 51 families, including 14 species of elasmobranch were recorded using Baited Remote Underwater Video systems (BRUVs) and unbaited Remote Underwater Video systems (RUVS) from 231 samples. Fish were significantly more abundant when observed using BRUVs (119 ± 7) relative to RUVs (92 ± 7), and the assemblage structures were significantly different between the two sampling methods. Abundance and species richness of generalist carnivores and piscivores were significantly greater in BRUVs, while RUVs recorded significantly greater numbers of herbivores and more species of herbivore and corallivore. The results suggest that BRUVs are better suited when studying predatory fish which may not be detected without bait. However, when surveying a taxonomically and functionally diverse assemblage of fishes at a pristine reef, RUVs may provide a more accurate estimate of natural reef fish assemblage structure. Reef fish assemblages observed using RUVs were significantly different between morning-high-tide, midday-low-tide and evening-high-tide for all trophic groups. However, the reef fish assemblage structure observed using BRUVs was insensitive to change in tide and time of day, which may be explained by the attraction effect of bait dampening the effect of tide and time of day. While RUVs appear better to detect more subtle variations in fish assemblage structure, care needs to be taken when designing research programmes that use RUVs, as the sampling design should account for tide and time of day to avoid misinterpreting the cyclical variation, which may confound results. Reef fish assemblages were significantly different among habitats within geomorphic reef zones, broad-scale and fine-scale habitats. Species turnover rates were significantly different for all Actinopterygii size-class categories between the three scales of habitat. No marked differences in species turnover rates among habitats were detected for the majority of Elasmobranch size-class categories. The strong habitat dependency over various spatial scales indicates that effective conservation of Actinopterygii fish at Aldabra, and elsewhere in similar ecosystems requires protection of representative sets of benthic habitats. However, Elasmobranch conservation requires sufficiently large areas as these species utilise multiple habitats, over multiple scales, which are likely to exceed the confines of Aldabra’s reef.
- Full Text:
- Date Issued: 2020
- Authors: Haupt, Philip
- Date: 2020
- Subjects: Coral reef ecology -- Aldabra Islands (Seychelles) , Reef fishes -- Aldabra Islands (Seychelles) , Benthic animals -- Aldabra Islands (Seychelles)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/141629 , vital:37991
- Description: The aim of the thesis is to develop an understanding of the associations between reef fish and benthic habitats and assess the modifying effects of environmental processes on these relationships at Aldabra, a pristine atoll in the Western Indian Ocean (WIO). Conducting research in pristine, or reference coral reef ecosystem, removes the impact of direct anthropogenic disturbances and provides essential information on natural ecosystem structure and functioning. Three primary hypotheses were tested: 1) Environmental drivers such as depth and exposure to wave energy determine the spatial distribution of benthic habitats; 2) The reef fish assemblage structure is explained by habitat at multiple scales and modified by the effects of environmental drivers such as depth, wave energy and cyclical temporal drivers such as time and tides; 3) The reef fish assemblage at Aldabra represents a pristine reef fish assemblage, comprising high levels of herbivores and predators. The research focussed on the benthic habitat on the seaward reefs between the shoreline and 50 m depth. The first objective was to characterise the benthic habitats on Aldabra Atoll’s seaward reefs and map their spatial distributions using remotely sensed imagery and ground truthing data. The second was to assess the influence of depth and exposure to wave energy on the distribution of benthic habitats. The third was to identify the most suitable standardised method to survey the reef fish assemblage structure on Aldabra’s, and fourth to determine the effect of tide and time of day on the reef fish assemblage. The fifth objective was to establish the association between reef fish assemblage structure and benthic habitats and to test how species-size influenced the scale of habitat at which the associations were most apparent. Four categories of geomorphic reef zones (reef flats (19.2 km2), top of the forereef slope (7.8 km2), deep forereef slope (11.6 km2), and reef platform (14.3 km2)) were manually delineated following the visual outlines of reef features from satellite imagery. The six broad-scale and twelve fine-scale benthic habitats were mapped using a supervised maximum likelihood classification and the spatial coverage of each determined. The broad-scale habitats were 1) Epilithic algal matrix, 2) Hard and soft (coral, 3) Rubble, 4) Macroalgae, 5) Seagrass and 6) Sand. Similarly, twelve fine-scale benthic habitats were characterised and mapped, for example, Hard coral (19 %) including massive and submassive forms with Millepora and Rhytisma. The broad-scale benthic habitat map had an overall producer accuracy of 54 % and fine-scale habitat map 29 %, which was consistent with studies using similar habitat classification methods. The prevailing wave energy, depth and the directional orientation of coral reefs (aspect) significantly influenced the probability of occurrence of each of the broad-scale benthic habitats, and there was a shift in peak probability of occurrence of all habitat categories to a greater depth with an increase in wave energy. The strong relationship of benthic habitats with depth and wave energy suggests that the distributions of benthic habitats are likely to change with sea-level rise and increased intensity and frequency of storms in future. Overall, 338 fish species from 51 families, including 14 species of elasmobranch were recorded using Baited Remote Underwater Video systems (BRUVs) and unbaited Remote Underwater Video systems (RUVS) from 231 samples. Fish were significantly more abundant when observed using BRUVs (119 ± 7) relative to RUVs (92 ± 7), and the assemblage structures were significantly different between the two sampling methods. Abundance and species richness of generalist carnivores and piscivores were significantly greater in BRUVs, while RUVs recorded significantly greater numbers of herbivores and more species of herbivore and corallivore. The results suggest that BRUVs are better suited when studying predatory fish which may not be detected without bait. However, when surveying a taxonomically and functionally diverse assemblage of fishes at a pristine reef, RUVs may provide a more accurate estimate of natural reef fish assemblage structure. Reef fish assemblages observed using RUVs were significantly different between morning-high-tide, midday-low-tide and evening-high-tide for all trophic groups. However, the reef fish assemblage structure observed using BRUVs was insensitive to change in tide and time of day, which may be explained by the attraction effect of bait dampening the effect of tide and time of day. While RUVs appear better to detect more subtle variations in fish assemblage structure, care needs to be taken when designing research programmes that use RUVs, as the sampling design should account for tide and time of day to avoid misinterpreting the cyclical variation, which may confound results. Reef fish assemblages were significantly different among habitats within geomorphic reef zones, broad-scale and fine-scale habitats. Species turnover rates were significantly different for all Actinopterygii size-class categories between the three scales of habitat. No marked differences in species turnover rates among habitats were detected for the majority of Elasmobranch size-class categories. The strong habitat dependency over various spatial scales indicates that effective conservation of Actinopterygii fish at Aldabra, and elsewhere in similar ecosystems requires protection of representative sets of benthic habitats. However, Elasmobranch conservation requires sufficiently large areas as these species utilise multiple habitats, over multiple scales, which are likely to exceed the confines of Aldabra’s reef.
- Full Text:
- Date Issued: 2020
Resource recovery options in brewery effluent treatment using activated sludge and high rate algal ponds: assessing environmental impacts
- Authors: Taylor, Richard Peter
- Date: 2020
- Subjects: Sewage -- Purification -- Activated sludge process , Sewage disposal plants , Sewage -- Purification -- Biological treatament , Sewage -- Purification -- Nitrogen removal , Brewery waste , Breweries -- Waste disposal , Microalgae -- Biotechnology , Algal biofuels
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/153746 , vital:39507
- Description: Wastewater treatment plants (WWTPs) are designed to clean effluents, but they also consume resources and produce waste. Various treatment technologies allow for the recovery of energy, nutrients and water from effluents turning this waste into products, which increases their sustainability and decreases the impact of WWTPs on the environment. There is a lack of literature which comprehensively compares the treatment performances, environmental impacts and beneficial downstream uses of the biomass generated by high rate algal pond (HRAP) and activated sludge (AS) treatment systems. This thesis aimed to compare (1) effluent treatment performance, (2) emissions and (3) downstream use of algae cultured in HRAP to sludge produced in AS and to obtain data to conduct a life cycle analysis (LCA) to compare the systems. The focus was on adding value to the effluent treatment process, while identifying the associated environmental impacts and contributing to the first ever zero-waste brewery effluent treatment system. Furthermore, these data were used to provide a basis to critically review and contribute to improving the methods used in the LCA of effluent treatment systems; particularly since this was the first wastewater treatment LCA that compared AS and HRAP using data collected from the same temporal and geographic location and from a single effluent stream. The electrical consumption water emission and land application of waste biomass caused the major environmental impacts of both treatment systems. The HRAP had less than 50 % of the electrical energy consumption (0.11±0.01 kW/m3 of effluent treated) compared to the AS system (0.29±0.11 kW/m3) which resulted in the technology having a lower climate change, photochemical oxidant formation, freshwater and marine ecotoxicity and fossil fuel depletion impact. It is imperative to understand the method of electrical energy (fossil fuel vs renewable) generation when conducting a LCA and deciding which technologies to use, since they have a major influence on the aforementioned impacts. The biogas yield of algal and sludge substrates was similar with an average gas production of 241 ml/g volatile solids fed. Biogas from algae fed digesters had a significantly higher methane content (64.73±0.81 %) and lower carbon dioxide content (22.94±0.24 %) when compared to WAS fed digesters (60.08±0.18 % and 27.37±0.43 %) respectively due to it being a less oxidised substrate. Swiss chard plants (Beta vulgaris) fertilised with anaerobically digested (AD) algae or sludge had a significantly higher mean biweekly yield (5.08±0.73 kg/m2) when compared to the inorganic-fertiliser control (3.45±0.89 kg/m2; p<0.0001). No difference was observed in the soil’s physical fertility when algae or sludge were applied to the soil (p>0.05). The HRAP produced more biomass (317.18±27.76 g/m3) than the AS (83.12±64.91 g/m3), which resulted in a significantly greater downstream production of biogas and fertiliser per volume of effluent treated. According to the LCA, this also resulted in the HRAP system having a higher terrestrial ecotoxicity, due to the greater volume of solids and thus heavy metals applied to the soil. This interpretation can be misleading, because the mass of heavy metals released into the environment is the same for both systems, with a greater portion being applied to the land in the HRAP scenario and discharged into fresh water in the case of AS. Future LCA models should clarify if these biomasses are going to be applied to a single piece of land or multiple sites as this will influence the risk of contamination via pollutant build up in the soil. The application of sludge or algae on soil increased the soil’s sodium concentration and sodium absorption ratio from 774.80±13.66 mg/kg to 952.17±34.89 mg/kg and 2.91±0.04 to 3.53±0.13, respectively. Regulations on the application of algae or sludge on agricultural soils should be altered to consider the limit values for sodium and future LCA’s associated with effluent treatment facilities should incorporate the possibility of soil contamination through sodium build-up. This work also conceptualised the importance of reporting water emissions in wastewater treatment LCA in as much detail as possible, because this had a significant influence on the eutrophication impacts on water systems. Reporting water emissions as total nitrogen underestimated downstream eutrophication impacts compared with those using nitrogen-species concentration (ammonia, nitrite, nitrate etc). A marine eutrophication sensitivity co-efficient should be included in future LCA models which accounts for the probability of nitrogen and phosphorus emissions entering the coastal environment as well as the vulnerability of the marine environment to eutrophication. Activated sludge systems are favourable for situations where space is limited, were there are inadequate options for biomass disposal (biomass not be used in agriculture or AD) and were electricity is generated from a renewable source; whereas, HRAP are more suitable under circumstances where electricity production relies on fossil fuel that carries a high environmental impact and where options are available to use the biomass for economic gain such as biogas and fertiliser production. This thesis contributes towards a zero-waste brewery effluent treated process. The HRAP and AS treated effluent for reuse in the brewery or in agricultural irrigation. The solids were anaerobically digested, and the carbon was recovered as a biogas, while the digestate was applied as an agricultural fertiliser. This allowed for the recovery of water, nutrients and carbon.
- Full Text:
- Date Issued: 2020
- Authors: Taylor, Richard Peter
- Date: 2020
- Subjects: Sewage -- Purification -- Activated sludge process , Sewage disposal plants , Sewage -- Purification -- Biological treatament , Sewage -- Purification -- Nitrogen removal , Brewery waste , Breweries -- Waste disposal , Microalgae -- Biotechnology , Algal biofuels
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/153746 , vital:39507
- Description: Wastewater treatment plants (WWTPs) are designed to clean effluents, but they also consume resources and produce waste. Various treatment technologies allow for the recovery of energy, nutrients and water from effluents turning this waste into products, which increases their sustainability and decreases the impact of WWTPs on the environment. There is a lack of literature which comprehensively compares the treatment performances, environmental impacts and beneficial downstream uses of the biomass generated by high rate algal pond (HRAP) and activated sludge (AS) treatment systems. This thesis aimed to compare (1) effluent treatment performance, (2) emissions and (3) downstream use of algae cultured in HRAP to sludge produced in AS and to obtain data to conduct a life cycle analysis (LCA) to compare the systems. The focus was on adding value to the effluent treatment process, while identifying the associated environmental impacts and contributing to the first ever zero-waste brewery effluent treatment system. Furthermore, these data were used to provide a basis to critically review and contribute to improving the methods used in the LCA of effluent treatment systems; particularly since this was the first wastewater treatment LCA that compared AS and HRAP using data collected from the same temporal and geographic location and from a single effluent stream. The electrical consumption water emission and land application of waste biomass caused the major environmental impacts of both treatment systems. The HRAP had less than 50 % of the electrical energy consumption (0.11±0.01 kW/m3 of effluent treated) compared to the AS system (0.29±0.11 kW/m3) which resulted in the technology having a lower climate change, photochemical oxidant formation, freshwater and marine ecotoxicity and fossil fuel depletion impact. It is imperative to understand the method of electrical energy (fossil fuel vs renewable) generation when conducting a LCA and deciding which technologies to use, since they have a major influence on the aforementioned impacts. The biogas yield of algal and sludge substrates was similar with an average gas production of 241 ml/g volatile solids fed. Biogas from algae fed digesters had a significantly higher methane content (64.73±0.81 %) and lower carbon dioxide content (22.94±0.24 %) when compared to WAS fed digesters (60.08±0.18 % and 27.37±0.43 %) respectively due to it being a less oxidised substrate. Swiss chard plants (Beta vulgaris) fertilised with anaerobically digested (AD) algae or sludge had a significantly higher mean biweekly yield (5.08±0.73 kg/m2) when compared to the inorganic-fertiliser control (3.45±0.89 kg/m2; p<0.0001). No difference was observed in the soil’s physical fertility when algae or sludge were applied to the soil (p>0.05). The HRAP produced more biomass (317.18±27.76 g/m3) than the AS (83.12±64.91 g/m3), which resulted in a significantly greater downstream production of biogas and fertiliser per volume of effluent treated. According to the LCA, this also resulted in the HRAP system having a higher terrestrial ecotoxicity, due to the greater volume of solids and thus heavy metals applied to the soil. This interpretation can be misleading, because the mass of heavy metals released into the environment is the same for both systems, with a greater portion being applied to the land in the HRAP scenario and discharged into fresh water in the case of AS. Future LCA models should clarify if these biomasses are going to be applied to a single piece of land or multiple sites as this will influence the risk of contamination via pollutant build up in the soil. The application of sludge or algae on soil increased the soil’s sodium concentration and sodium absorption ratio from 774.80±13.66 mg/kg to 952.17±34.89 mg/kg and 2.91±0.04 to 3.53±0.13, respectively. Regulations on the application of algae or sludge on agricultural soils should be altered to consider the limit values for sodium and future LCA’s associated with effluent treatment facilities should incorporate the possibility of soil contamination through sodium build-up. This work also conceptualised the importance of reporting water emissions in wastewater treatment LCA in as much detail as possible, because this had a significant influence on the eutrophication impacts on water systems. Reporting water emissions as total nitrogen underestimated downstream eutrophication impacts compared with those using nitrogen-species concentration (ammonia, nitrite, nitrate etc). A marine eutrophication sensitivity co-efficient should be included in future LCA models which accounts for the probability of nitrogen and phosphorus emissions entering the coastal environment as well as the vulnerability of the marine environment to eutrophication. Activated sludge systems are favourable for situations where space is limited, were there are inadequate options for biomass disposal (biomass not be used in agriculture or AD) and were electricity is generated from a renewable source; whereas, HRAP are more suitable under circumstances where electricity production relies on fossil fuel that carries a high environmental impact and where options are available to use the biomass for economic gain such as biogas and fertiliser production. This thesis contributes towards a zero-waste brewery effluent treated process. The HRAP and AS treated effluent for reuse in the brewery or in agricultural irrigation. The solids were anaerobically digested, and the carbon was recovered as a biogas, while the digestate was applied as an agricultural fertiliser. This allowed for the recovery of water, nutrients and carbon.
- Full Text:
- Date Issued: 2020
Rural enterprise development as a means to poverty alleviation
- Authors: Bodley, David Cyril
- Date: 2020
- Subjects: Rural development -- South Africa , Economic development projects -- South Africa Poverty alleviation -- methods -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/50361 , vital:42118
- Description: South Africa’s disappointing economic performance over the last decade has resulted in a socio-economic crisis, with unemployment and inequality rates being of the highest rates anywhere in the world. Furthermore, unemployment is concentrated among the young, unskilled, and previously disadvantaged population posing a considerable threat to South Africa’s new democracy. Internationally, a method to absorb job seekers into the economy is to make small business the engine-room of economic growth and development. Consequently, the South African Government has identified in its National Development Plan the establishment of small businesses as a priority, including the development of small businesses in rural and marginalised communities. As rural communities in South Africa experience systemic problems such as the lack of infrastructure, financial capital, skills and potential markets, establishing enterprises in rural settings is often more complex than those more advanced parts of the economy elsewhere where fewer constraints exist. This makes the task of establishing and growing rural entities particularly challenging, suggesting bespoke policy and support is required. This study analyses the literature to gain an understanding of economic development theory and how this intersects with and informs small enterprise development policy. It then looks at South Africa’s strategy and policy framework pertaining to enterprise development. Specifically, the literature examines the role of rural enterprise development to establish whether this enables people to move out of poverty or further entraps people in poverty. The study collates data from a rural and marginalised community through observation and interview techniques. Firstly, multiple in-depth interviews were conducted with nineteen entrepreneurs in a rural community to collect data on business opportunities and explore the type of support entrepreneurs would require from government. Secondly, a focus group interview was conducted with entrepreneurs that had experienced institutional support to understand how well current policy and programmes support rural enterprise development. The primary data was analysed in conjunction with the literature on economic theory and enterprise development using the technique of triangulation to avoid logic leaps and formation of false assumptions. The insights and findings from the analysis reinforced certain facts within the body of knowledge pertaining to enterprise development, but there were also some interesting new insights that emanate from the data. South Africa has been able to introduce a wide range of policy initiatives and has multiple programmes and strategies to support small enterprise development. It has achieved firm success and impetus as well as experiencing certain failures. The study clearly highlights both and makes recommendations to improve policy promoting rural enterprise development as a means to alleviate poverty.
- Full Text:
- Date Issued: 2020
- Authors: Bodley, David Cyril
- Date: 2020
- Subjects: Rural development -- South Africa , Economic development projects -- South Africa Poverty alleviation -- methods -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/50361 , vital:42118
- Description: South Africa’s disappointing economic performance over the last decade has resulted in a socio-economic crisis, with unemployment and inequality rates being of the highest rates anywhere in the world. Furthermore, unemployment is concentrated among the young, unskilled, and previously disadvantaged population posing a considerable threat to South Africa’s new democracy. Internationally, a method to absorb job seekers into the economy is to make small business the engine-room of economic growth and development. Consequently, the South African Government has identified in its National Development Plan the establishment of small businesses as a priority, including the development of small businesses in rural and marginalised communities. As rural communities in South Africa experience systemic problems such as the lack of infrastructure, financial capital, skills and potential markets, establishing enterprises in rural settings is often more complex than those more advanced parts of the economy elsewhere where fewer constraints exist. This makes the task of establishing and growing rural entities particularly challenging, suggesting bespoke policy and support is required. This study analyses the literature to gain an understanding of economic development theory and how this intersects with and informs small enterprise development policy. It then looks at South Africa’s strategy and policy framework pertaining to enterprise development. Specifically, the literature examines the role of rural enterprise development to establish whether this enables people to move out of poverty or further entraps people in poverty. The study collates data from a rural and marginalised community through observation and interview techniques. Firstly, multiple in-depth interviews were conducted with nineteen entrepreneurs in a rural community to collect data on business opportunities and explore the type of support entrepreneurs would require from government. Secondly, a focus group interview was conducted with entrepreneurs that had experienced institutional support to understand how well current policy and programmes support rural enterprise development. The primary data was analysed in conjunction with the literature on economic theory and enterprise development using the technique of triangulation to avoid logic leaps and formation of false assumptions. The insights and findings from the analysis reinforced certain facts within the body of knowledge pertaining to enterprise development, but there were also some interesting new insights that emanate from the data. South Africa has been able to introduce a wide range of policy initiatives and has multiple programmes and strategies to support small enterprise development. It has achieved firm success and impetus as well as experiencing certain failures. The study clearly highlights both and makes recommendations to improve policy promoting rural enterprise development as a means to alleviate poverty.
- Full Text:
- Date Issued: 2020