Mechatronics based highspeed rotational piezo actuator
- Authors: Raffler, Oliver
- Date: 2020
- Subjects: Piezoelectric materials , Piezoelectric devices Mechatronics
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/${Handle} , vital:39811
- Description: The aim of this thesis is the development of a novel mechatronics-based high speed piezo actuator for rotational and linear motion. Mainly, the thesis deals with the development of a system for mechanical coupling of any number of piezostacks. This mechanical coupling allows the actuator to achieve a significantly increased deflection compared to current approaches. The developed concept offers the possibility of a linear or rotary motion. It is also possible to combine the two types of movement. In the first step, in order to gain a better understanding of the topic, the piezo technology and especially the existing piezo actuators and -motors are examined. Currently, the force generated by the piezo actuators is mainly transmitted by friction. The only exception is the PAD-Actuator, which transmits force by means of form locking. The concept developed here also transmits its force by means of form locking and, in addition to that, offers a novel and unique drive concept in the field of piezo actuators. In the course of this thesis a new concept for the mechanical coupling of piezo actuators was developed, simulated and subsequently manufactured. Thus the system could be examined under real conditions. The investigations carried out mainly dealt with quasi-static and dynamic investigations. In addition to that, the emission of the airborne and structure-borne noise of the system was analysed.
- Full Text:
- Date Issued: 2020
- Authors: Raffler, Oliver
- Date: 2020
- Subjects: Piezoelectric materials , Piezoelectric devices Mechatronics
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/${Handle} , vital:39811
- Description: The aim of this thesis is the development of a novel mechatronics-based high speed piezo actuator for rotational and linear motion. Mainly, the thesis deals with the development of a system for mechanical coupling of any number of piezostacks. This mechanical coupling allows the actuator to achieve a significantly increased deflection compared to current approaches. The developed concept offers the possibility of a linear or rotary motion. It is also possible to combine the two types of movement. In the first step, in order to gain a better understanding of the topic, the piezo technology and especially the existing piezo actuators and -motors are examined. Currently, the force generated by the piezo actuators is mainly transmitted by friction. The only exception is the PAD-Actuator, which transmits force by means of form locking. The concept developed here also transmits its force by means of form locking and, in addition to that, offers a novel and unique drive concept in the field of piezo actuators. In the course of this thesis a new concept for the mechanical coupling of piezo actuators was developed, simulated and subsequently manufactured. Thus the system could be examined under real conditions. The investigations carried out mainly dealt with quasi-static and dynamic investigations. In addition to that, the emission of the airborne and structure-borne noise of the system was analysed.
- Full Text:
- Date Issued: 2020
Meeting a diversity of needs through a diversity of species: Urban residents’ favourite and disliked tree species across eleven towns in South Africa and Zimbabwe
- Shackleton, Charlie M, Mograbi, Penelope J
- Authors: Shackleton, Charlie M , Mograbi, Penelope J
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/176321 , vital:42684 , https://doi.org/10.1016/j.ufug.2019.126507
- Description: Understanding of urban residents’ preferences and dislikes for tree species and attributes is necessary to provide them with the species they most favour. Yet there is relatively little understanding of local species preferences, the reasons underlying them and how they vary with context and scale. We interviewed 1100 urban residents in eleven towns (four in Zimbabwe, four in Limpopo Province and three in the Eastern Cape of South Africa) to determine what were their favourite and least favourite tree species and the reasons for such. Fifty-nine species were listed amongst the preferred species (the four most common being Jacaranda mimosifolia (10% or respondents), Mangifera indica (10%), Adonsonia digitata (7%) and Colophospermum mopane (7%)), and 29 as disliked (the four most common being Vachellia spp, J. mimosifolia, Euphorbia spp. and Melia azedarach), with 16 in common between the two.
- Full Text:
- Date Issued: 2020
- Authors: Shackleton, Charlie M , Mograbi, Penelope J
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/176321 , vital:42684 , https://doi.org/10.1016/j.ufug.2019.126507
- Description: Understanding of urban residents’ preferences and dislikes for tree species and attributes is necessary to provide them with the species they most favour. Yet there is relatively little understanding of local species preferences, the reasons underlying them and how they vary with context and scale. We interviewed 1100 urban residents in eleven towns (four in Zimbabwe, four in Limpopo Province and three in the Eastern Cape of South Africa) to determine what were their favourite and least favourite tree species and the reasons for such. Fifty-nine species were listed amongst the preferred species (the four most common being Jacaranda mimosifolia (10% or respondents), Mangifera indica (10%), Adonsonia digitata (7%) and Colophospermum mopane (7%)), and 29 as disliked (the four most common being Vachellia spp, J. mimosifolia, Euphorbia spp. and Melia azedarach), with 16 in common between the two.
- Full Text:
- Date Issued: 2020
Men in Women’s Clothes
- Authors: Jones, Ward E
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275658 , vital:55067 , xlink:href="https://doi.org/10.1111/sjp.12394"
- Description: The descriptive phrase that comprises my title can refer both to a pervasive comic trope and a mode of self-expression. There is a tension here, insofar as the comic trope leads us not to take cross-dressing, or drag, seriously. The first half of the comic film Some Like It Hot (1959), with its cross-gender plot and its (sophisticated but) straightforward use of the comic trope of men-in-women’s clothes, appears to fall foul of this tension and to be susceptible to criticism in this regard. However, the film rectifies itself, portraying the cross-dressing relationship which develops through the second half of the film as a potentially meaningful one for both partners. In this article, I interpret the film as inviting its viewers to adopt a (particular kind of) skeptical ironic (that is, Pyrrhonian) attitude toward gender-presentation practices. While the film in no way attempts to discourage us from participating in such practices, it does invite us—through our partiality toward the characters Osgood and Jerry/Daphne, as we follow their budding, transgressive relationship—to acknowledge that a violation of gender-presentation practices can be a meaningful feature of sincere relationships.
- Full Text:
- Date Issued: 2020
- Authors: Jones, Ward E
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275658 , vital:55067 , xlink:href="https://doi.org/10.1111/sjp.12394"
- Description: The descriptive phrase that comprises my title can refer both to a pervasive comic trope and a mode of self-expression. There is a tension here, insofar as the comic trope leads us not to take cross-dressing, or drag, seriously. The first half of the comic film Some Like It Hot (1959), with its cross-gender plot and its (sophisticated but) straightforward use of the comic trope of men-in-women’s clothes, appears to fall foul of this tension and to be susceptible to criticism in this regard. However, the film rectifies itself, portraying the cross-dressing relationship which develops through the second half of the film as a potentially meaningful one for both partners. In this article, I interpret the film as inviting its viewers to adopt a (particular kind of) skeptical ironic (that is, Pyrrhonian) attitude toward gender-presentation practices. While the film in no way attempts to discourage us from participating in such practices, it does invite us—through our partiality toward the characters Osgood and Jerry/Daphne, as we follow their budding, transgressive relationship—to acknowledge that a violation of gender-presentation practices can be a meaningful feature of sincere relationships.
- Full Text:
- Date Issued: 2020
Metabarcoding Analysis of Bacterial Communities Associated with Media Grow Bed Zones in an Aquaponic System
- Kasozi, Nasser, Kaiser, Horst, Wilhelmi, Brendan S
- Authors: Kasozi, Nasser , Kaiser, Horst , Wilhelmi, Brendan S
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429461 , vital:72612 , xlink:href="https://doi.org/10.1155/2020/8884070"
- Description: The development of environmentally sustainable plant and fish production in aquaponic systems requires a complete understanding of the systems’ biological components. In order to better understand the role of microorganisms in this association, we studied the bacterial communities in the dry, root, and mineralized zones of a flood-and-drain media bed aquaponic system. Bacterial communities were characterized using metabarcoding of the V3-V4 16S rRNA regions obtained from paired-end Illumina MiSeq reads. Proteobacteria, Actinobacteria, and Bacteroidetes accounted for more than 90% of the total community in the dry zone and the effluent water. These phyla also accounted for more than 68% of the total community in the root and mineralized zones. The genera Massilia, Mucilaginibacter, Mizugakiibacter, and Rhodoluna were most dominant in the dry, root, and mineralized zones and in the effluent water, respectively. The number of shared operational taxonomic units (OTUs) for the three zones was 241, representing 7.15% of the total observed OTUs. The number of unique OTUs in samples from dry zone, root zone, mineralized zone, and effluent water was 485, 638, 445, and 383, respectively. The samples from the root zone harbored more diverse communities than either the dry or mineralized zones. This study is the first to report on the bacterial community within the zones of a flood-and-drain media bed. Thus, this information will potentially accelerate studies on other microbial communities involved in the bioconversion of nitrogen compounds and mineralization within these types of aquaponic systems.
- Full Text:
- Date Issued: 2020
- Authors: Kasozi, Nasser , Kaiser, Horst , Wilhelmi, Brendan S
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429461 , vital:72612 , xlink:href="https://doi.org/10.1155/2020/8884070"
- Description: The development of environmentally sustainable plant and fish production in aquaponic systems requires a complete understanding of the systems’ biological components. In order to better understand the role of microorganisms in this association, we studied the bacterial communities in the dry, root, and mineralized zones of a flood-and-drain media bed aquaponic system. Bacterial communities were characterized using metabarcoding of the V3-V4 16S rRNA regions obtained from paired-end Illumina MiSeq reads. Proteobacteria, Actinobacteria, and Bacteroidetes accounted for more than 90% of the total community in the dry zone and the effluent water. These phyla also accounted for more than 68% of the total community in the root and mineralized zones. The genera Massilia, Mucilaginibacter, Mizugakiibacter, and Rhodoluna were most dominant in the dry, root, and mineralized zones and in the effluent water, respectively. The number of shared operational taxonomic units (OTUs) for the three zones was 241, representing 7.15% of the total observed OTUs. The number of unique OTUs in samples from dry zone, root zone, mineralized zone, and effluent water was 485, 638, 445, and 383, respectively. The samples from the root zone harbored more diverse communities than either the dry or mineralized zones. This study is the first to report on the bacterial community within the zones of a flood-and-drain media bed. Thus, this information will potentially accelerate studies on other microbial communities involved in the bioconversion of nitrogen compounds and mineralization within these types of aquaponic systems.
- Full Text:
- Date Issued: 2020
Metallophthalocyanines linked to metal nanoparticles and folic acid for use in photodynamic therapy of cancer and photoinactivation of bacterial microorganisms.
- Authors: Matlou, Gauta Gold
- Date: 2020
- Subjects: Cancer -- Photochemotherapy , Nanoparticles , Phthalocyanines , Anti-infective agents -- Therapeutic use , Photochemotherapy , Photochemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/166540 , vital:41377
- Description: This thesis presents on the synthesis and characterization of novel asymmetric and symmetrical metallophthalocyanines (MPcs) substituted with carboxylic acid functional groups and centrally metallated with zinc and indium. The MPcs are further covalently linked to cysteine capped silver nanoparticles (cys-AgNPs), amino functionalized magnetic nanoparticles (AMNPs) and folic acid (FA) through an amide bond between the carboxylic group of MPcs and the amino group of FA, cys-AgNPs or AMNPs. The covalent linkage of MPcs to FA improved the water solubility of MPcs and allowed for singlet oxygen quantum yield determination in water. Asymmetric MPcs and their conjugates were found to have improved photochemical and photophysical properties compared to symmetrical MPcs and their conjugates. The heavy atom effect of AMNPs and AgNPs improved the triplet and singlet oxygen quantum yields of MPcs. MPcs and their conjugates (MPc-FA, MPc-AMNPs, MPc-AgNPs) were found to have lower in vitro dark cytotoxicity and higher photodynamic therapy (PDT) activity on MCF-7 breast cancer cells. The water soluble MPc-FA had better PDT activity when compared to MPc-AMNPs due to the active targeting of folic acid-folate binding on cancer cell surface. MPcs and MPc-AgNPs conjugates also showed excellent in vitro cytotoxicity on S. aureus under light irradiation compared to dark cytotoxicity. The photosensitizing properties of MPcs and their conjugates are demonstrated for the first time in this thesis, both on breast cancer cells (MCF-7) through photodynamic therapy and on microorganisms (S. aureus) through photodynamic antimicrobial chemotherapy.
- Full Text:
- Date Issued: 2020
- Authors: Matlou, Gauta Gold
- Date: 2020
- Subjects: Cancer -- Photochemotherapy , Nanoparticles , Phthalocyanines , Anti-infective agents -- Therapeutic use , Photochemotherapy , Photochemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/166540 , vital:41377
- Description: This thesis presents on the synthesis and characterization of novel asymmetric and symmetrical metallophthalocyanines (MPcs) substituted with carboxylic acid functional groups and centrally metallated with zinc and indium. The MPcs are further covalently linked to cysteine capped silver nanoparticles (cys-AgNPs), amino functionalized magnetic nanoparticles (AMNPs) and folic acid (FA) through an amide bond between the carboxylic group of MPcs and the amino group of FA, cys-AgNPs or AMNPs. The covalent linkage of MPcs to FA improved the water solubility of MPcs and allowed for singlet oxygen quantum yield determination in water. Asymmetric MPcs and their conjugates were found to have improved photochemical and photophysical properties compared to symmetrical MPcs and their conjugates. The heavy atom effect of AMNPs and AgNPs improved the triplet and singlet oxygen quantum yields of MPcs. MPcs and their conjugates (MPc-FA, MPc-AMNPs, MPc-AgNPs) were found to have lower in vitro dark cytotoxicity and higher photodynamic therapy (PDT) activity on MCF-7 breast cancer cells. The water soluble MPc-FA had better PDT activity when compared to MPc-AMNPs due to the active targeting of folic acid-folate binding on cancer cell surface. MPcs and MPc-AgNPs conjugates also showed excellent in vitro cytotoxicity on S. aureus under light irradiation compared to dark cytotoxicity. The photosensitizing properties of MPcs and their conjugates are demonstrated for the first time in this thesis, both on breast cancer cells (MCF-7) through photodynamic therapy and on microorganisms (S. aureus) through photodynamic antimicrobial chemotherapy.
- Full Text:
- Date Issued: 2020
Microbial fuel cells for remediation of metal rich wastewater coupled with bioelectricity generation
- Authors: Mshoperi, Edith
- Date: 2020
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/124112 , vital:35540
- Description: Expected release date-April 2022
- Full Text: false
- Date Issued: 2020
Microbial fuel cells for remediation of metal rich wastewater coupled with bioelectricity generation
- Authors: Mshoperi, Edith
- Date: 2020
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/124112 , vital:35540
- Description: Expected release date-April 2022
- Full Text: false
- Date Issued: 2020
Microfinances efficiencies in promoting sustainability of women owned SMMEs in Port Elizabeth
- Authors: Koti, Kundai
- Date: 2020
- Subjects: Microfinance -- South Africa -- Eastern Cape , Women owned business enterprises
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/49870 , vital:41811
- Description: Microfinance is considered to be a vital catalyst for the sustainability of small, micro and medium enterprises (SMMEs).The low economic growth of South Africa emerging from the 2008 Global Financia Crisis makes the contribution made by microfinance is of particular importance. However, the SMME sector of the economy is plagued by a high rate of business failure. In an effort to improve the current situation, the purpose of this study was to identify which aspects of microfinance are vital and which business practices are essential to enhance business performance and achieve sustainability. The effectiveness of microfinance, with a deeper insight into what other factors aid in enhancing the sustainability of women owned SMMEs, were investigated. The study was carried out as an explorative, multiple, case study using qualitative methods of data collection. Qualitative data were collected using semi-structured interviews with three managers of microfinance institutions (MFIs), and open-ended questionnaires with 21 female owners of SMMEs in Port Elizabeth, Nelson Mandela Bay. Nonprobability, purposive sampling was used. Data were analysed by means of thematic analysis and coding.
- Full Text:
- Date Issued: 2020
- Authors: Koti, Kundai
- Date: 2020
- Subjects: Microfinance -- South Africa -- Eastern Cape , Women owned business enterprises
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/49870 , vital:41811
- Description: Microfinance is considered to be a vital catalyst for the sustainability of small, micro and medium enterprises (SMMEs).The low economic growth of South Africa emerging from the 2008 Global Financia Crisis makes the contribution made by microfinance is of particular importance. However, the SMME sector of the economy is plagued by a high rate of business failure. In an effort to improve the current situation, the purpose of this study was to identify which aspects of microfinance are vital and which business practices are essential to enhance business performance and achieve sustainability. The effectiveness of microfinance, with a deeper insight into what other factors aid in enhancing the sustainability of women owned SMMEs, were investigated. The study was carried out as an explorative, multiple, case study using qualitative methods of data collection. Qualitative data were collected using semi-structured interviews with three managers of microfinance institutions (MFIs), and open-ended questionnaires with 21 female owners of SMMEs in Port Elizabeth, Nelson Mandela Bay. Nonprobability, purposive sampling was used. Data were analysed by means of thematic analysis and coding.
- Full Text:
- Date Issued: 2020
Microplastic leachates induce species-specific trait strengthening in intertidal mussels:
- Seuront, Laurent, Nicastro, Katy R, McQuaid, Christopher D, Zardi, Gerardo I
- Authors: Seuront, Laurent , Nicastro, Katy R , McQuaid, Christopher D , Zardi, Gerardo I
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158200 , vital:40162 , https://0-doi.org.wam.seals.ac.za/10.1002/eap.2222. https://doi.org/10.5061/dryad.905qftthq
- Description: Plastic pollution is ubiquitous with increasing recognition of its direct effects on species’ fitness. Little is known, however, about its more subtle effects, including the influence of plastic pollution on the morphological, functional and behavioural traits of organisms that are central to their ability to withstand disturbances. Among the least obvious but most pernicious forms of plastic-associated pollution are the chemicals that leach from microplastics. Here, we investigate how such leachates influence species’ traits by assessing functional trait compensation across four species of intertidal mussels, through investigations of byssal thread production, movement and aggregation behaviour for mussels held in natural seawater or seawater contaminated by microplastic leachates.
- Full Text:
- Date Issued: 2020
- Authors: Seuront, Laurent , Nicastro, Katy R , McQuaid, Christopher D , Zardi, Gerardo I
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158200 , vital:40162 , https://0-doi.org.wam.seals.ac.za/10.1002/eap.2222. https://doi.org/10.5061/dryad.905qftthq
- Description: Plastic pollution is ubiquitous with increasing recognition of its direct effects on species’ fitness. Little is known, however, about its more subtle effects, including the influence of plastic pollution on the morphological, functional and behavioural traits of organisms that are central to their ability to withstand disturbances. Among the least obvious but most pernicious forms of plastic-associated pollution are the chemicals that leach from microplastics. Here, we investigate how such leachates influence species’ traits by assessing functional trait compensation across four species of intertidal mussels, through investigations of byssal thread production, movement and aggregation behaviour for mussels held in natural seawater or seawater contaminated by microplastic leachates.
- Full Text:
- Date Issued: 2020
Mineral Resources Governance and Socio-Economic Development in Zimbabwe
- Authors: Chawatama, Chrispen Tauya
- Date: 2020
- Subjects: Mines and mineral resources -- Zimbabwe Mining law --Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD(Dev)
- Identifier: http://hdl.handle.net/${Handle} , vital:42996
- Description: This study focused on investigating mineral resources governance (reflected in terms of three indicators of transparency, accountability and stakeholder inclusion) and its effect on socioeconomic development (in terms of three indicators of education, health and household incomes. Mineral resources can be a blessing and can lead to socioeconomic transformation of a country if they are managed transparently, accountably, inclusively equitably and sustainably. On the other hand, these subsoil capital assets can be a ‘curse’ and lead to poverty, conflicts amongst interest groups, elite capture, corruption and economic stagnation if they are not properly managed. Good governance of mineral resources seeks to ensure that the harnessing of mineral resources benefits the economy, enhances the quality of life and reduces poverty amongst citizens. The mining sector of Zimbabwe has risen to be the key economic sector in terms of its contribution to the GDP, FDI, fiscal revenue, exports and employment creation, particularly after the discovery of diamonds and more gold deposits in the country. However, in spite of the growth of the mining sector and its elevation to the mainstay of the economy, glaring dire socioeconomic conditions in terms of unemployment and high poverty levels, poor health, education and household incomes, leads one to question the way the country’s opulent mineral resources are being governed. The study used a mixed methods approach, through use of primary data (quantitative and qualitative data) and secondary data (archival data) as the basis for the collection as well as analysis of data. Complementarity of the research methods was achieved through use of data from household survey with 160 households in Mhondoro-Ngezi, Chegutu, Kwekwe and Shurugwi and in-depth interviews with officials of government ministries; of Finance and Economic Development, Health and Childcare, Primary and viii Secondary Education, local councillors, CSOs; ZELA and ZIMCODD, Traditional chiefs and ZASMC. The study established that mining growth is contributing somewhat to socio-economic development through employment creation, corporate social responsibility, CSOTs, ESPOs, taxation and royalties, but broad-based development has not taken place in the four districts. The study proposes a holistic mineral resources governance and socioeconomic development framework. The study recommends the Repeal of MMA and gazetting of a more comprehensive legal framework, implementation of constitutional provisions on transparency, accountability and stakeholder inclusion, adoption of free online tools for mineral processes disclosure, consolidation of the mining fiscal regime and so on.
- Full Text:
- Date Issued: 2020
- Authors: Chawatama, Chrispen Tauya
- Date: 2020
- Subjects: Mines and mineral resources -- Zimbabwe Mining law --Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD(Dev)
- Identifier: http://hdl.handle.net/${Handle} , vital:42996
- Description: This study focused on investigating mineral resources governance (reflected in terms of three indicators of transparency, accountability and stakeholder inclusion) and its effect on socioeconomic development (in terms of three indicators of education, health and household incomes. Mineral resources can be a blessing and can lead to socioeconomic transformation of a country if they are managed transparently, accountably, inclusively equitably and sustainably. On the other hand, these subsoil capital assets can be a ‘curse’ and lead to poverty, conflicts amongst interest groups, elite capture, corruption and economic stagnation if they are not properly managed. Good governance of mineral resources seeks to ensure that the harnessing of mineral resources benefits the economy, enhances the quality of life and reduces poverty amongst citizens. The mining sector of Zimbabwe has risen to be the key economic sector in terms of its contribution to the GDP, FDI, fiscal revenue, exports and employment creation, particularly after the discovery of diamonds and more gold deposits in the country. However, in spite of the growth of the mining sector and its elevation to the mainstay of the economy, glaring dire socioeconomic conditions in terms of unemployment and high poverty levels, poor health, education and household incomes, leads one to question the way the country’s opulent mineral resources are being governed. The study used a mixed methods approach, through use of primary data (quantitative and qualitative data) and secondary data (archival data) as the basis for the collection as well as analysis of data. Complementarity of the research methods was achieved through use of data from household survey with 160 households in Mhondoro-Ngezi, Chegutu, Kwekwe and Shurugwi and in-depth interviews with officials of government ministries; of Finance and Economic Development, Health and Childcare, Primary and viii Secondary Education, local councillors, CSOs; ZELA and ZIMCODD, Traditional chiefs and ZASMC. The study established that mining growth is contributing somewhat to socio-economic development through employment creation, corporate social responsibility, CSOTs, ESPOs, taxation and royalties, but broad-based development has not taken place in the four districts. The study proposes a holistic mineral resources governance and socioeconomic development framework. The study recommends the Repeal of MMA and gazetting of a more comprehensive legal framework, implementation of constitutional provisions on transparency, accountability and stakeholder inclusion, adoption of free online tools for mineral processes disclosure, consolidation of the mining fiscal regime and so on.
- Full Text:
- Date Issued: 2020
Mineralogy, geochemistry and origin of the Neoproterozoic Xaudum iron-formation in Botswana
- Authors: Ntantiso, Mawande
- Date: 2020
- Subjects: Xaudum iron-formation , Iron ores -- Botswana , Formations (Geology) -- Botswana , Mineralogy -- Botswana , Paleoclimatology -- Proterozoic
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167211 , vital:41447
- Description: Banded iron-formations (BIF) formed in three different geological periods in the Earth’s history, namely the Archean, Paleoproterozoic and Neoproterozoic. Each of these periods has a corresponding index BIF type attributed to them. The oldest is the Archean Algoma-type BIF which is typically dominated by smaller-volume BIF deposits associated with volcanic rocks and greenstone belts. The next is the volumetrically far more abundant Superior-type BIF of the Paleoproterozoic lacking any obvious volcanic relation. The youngest BIFs were deposited after a hiatus of a billion years in the Neoproterozoic and are believed to be genetically linked to Marinoan ice-age. The global re-introduction and distribution of BIF in the Neoproterozoic highlights a shift in the Earth’s tectonics, climate, biosphere and ocean chemistry from the older Archean and Paleoproterozoic counterparts. Various models have been postulated by researchers in attempts to explain how Neoproterozoic iron-formations formed. In all the available models, the Snowball Earth Hypothesis initially proposed by Kirshvink (1992) is an overarching concept. In this study, four cores from the Neoproterozoic Xaudum iron-formation (XIF) in Ngamiland, northwest of Botswana, were sampled and analysed following a partnership between Postgraduate Research in Iron and Manganese Ore Resources (PRIMOR) and Tsodilo Resources Ltd. The study sets out to explore the mineralogy and chemistry of XIF in order to determine its origin, constrain the redox conditions in the paleo-basin, assess it in the context of other Neoproterozoic iron-formations and older Archean and Paleoproterozoic iron-formations, and inform metallurgical processing. The mineralogy of XIF consists of magnetite, quartz, amphibole, garnet, biotite and chlorite in decreasing abundance. This mineral assemblage is characteristic of medium grade metamorphosed iron-formations. Algoma and Superior-type BIFs which experienced late-diagenetic and very low-grade metamorphism have a complex mineral assemblage consisting of hematite, magnetite, quartz, and several carbonate (dolomite-ankerite series and siderite) and silicate phases (greenalite, riebeckite and stilpnomelane). The geochemical results show that XIF has higher Mn3O4 and Al2O3 average contents when compared to Algoma and Superior type BIF. The detrital components in XIF correlate with High Field Strength Elements (HFSE) suggesting increased delivery of siliciclastic material during deposition. This trend is comparable to other NIF deposits suggesting a global high input of siliciclastic material into Neoproterozoic paleodepositional environments. This trend is different from Archean and Paleoproterozoic BIF deposits which are close to pure chemical sediments lacking measurable detrital contributions. In the XIF, bulk-rock Mn3O4 and Al2O3 in drillcore SW have higher averages of 2.4 and 2.6 wt. % respectively, compared to the other three cores. The Mn3O4 shows a positive statistical relationship with Co, suggesting that Neoproterozoic oceans and atmosphere were possibly more oxic than in the Archean and Paleoproterozoic. The Mn3O4 shows an antithetic relationship with Fe2O3 suggesting that the paleobasin was chemically heterogeneous in terms of redox conditions, with Fe2O3 depositing presumably in deeper parts removed from a detrital source, and Mn3O4 depositing possibly more proximal to a paleo-shoreline in a shallower setting where there was higher delivery of siliciclastic material from the continent due to correspondingly higher Al2O3 and TiO2 contents. The REE patterns of XIF show positive-sloping trends of depletion in LREE and enrichment in HREE which resemble those of seawater. However, the REE slope becomes a lot flatter and resembles closer the signature of PAAS and adjacent diamictite facies, which agrees with the idea of high siliciclastic input in the paleobasin comparable to other NIF. XIF also appears to lack clear Ce or Eu anomalies. The lack of the former points to the oceans possibly not being oxic enough to drive the fractionation of Ce into Mn oxides like in the modern oceans, or that the Ce behaviour is obscured by the high siliciclastic input in XIF. Similarly, the lack of positive Eu anomaly shows a weak to absent hydrothermal signal into to modern shallow seawater where Fe and Si were sourced, or detritally derived REE contamination. Extensive weathering under hot and humid climate during glacial retreat is shown by the low K2O/Al2O3 ratios and high CIA values ranging from 80-99. Re-glaciation signifies the return of cold and arid and it is represented by high K2O/Al2O3 ratios and low CIA values ranging from 64-78. The previous genetic models of NIF by Klein (1993), Baldwin et al. (2012) and Lechte and Wallace (2015) provide an essential foundation for the development of a XIF genetic model. The genetic model of XIF proposes deposition on an open continental shelf characterized by a steady influx of detrital material. The seawater has been anoxic since the Paleoproterozoic and further induced by basin stagnation due to the ice covering the basin. Two overlapping oxidative stages are assumed for the precipitation of Fe and Mn across lateral redox gradients in the paleobasin. The exact oxidative pathways and mechanisms for the above processes remains unconstrained.
- Full Text:
- Date Issued: 2020
- Authors: Ntantiso, Mawande
- Date: 2020
- Subjects: Xaudum iron-formation , Iron ores -- Botswana , Formations (Geology) -- Botswana , Mineralogy -- Botswana , Paleoclimatology -- Proterozoic
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167211 , vital:41447
- Description: Banded iron-formations (BIF) formed in three different geological periods in the Earth’s history, namely the Archean, Paleoproterozoic and Neoproterozoic. Each of these periods has a corresponding index BIF type attributed to them. The oldest is the Archean Algoma-type BIF which is typically dominated by smaller-volume BIF deposits associated with volcanic rocks and greenstone belts. The next is the volumetrically far more abundant Superior-type BIF of the Paleoproterozoic lacking any obvious volcanic relation. The youngest BIFs were deposited after a hiatus of a billion years in the Neoproterozoic and are believed to be genetically linked to Marinoan ice-age. The global re-introduction and distribution of BIF in the Neoproterozoic highlights a shift in the Earth’s tectonics, climate, biosphere and ocean chemistry from the older Archean and Paleoproterozoic counterparts. Various models have been postulated by researchers in attempts to explain how Neoproterozoic iron-formations formed. In all the available models, the Snowball Earth Hypothesis initially proposed by Kirshvink (1992) is an overarching concept. In this study, four cores from the Neoproterozoic Xaudum iron-formation (XIF) in Ngamiland, northwest of Botswana, were sampled and analysed following a partnership between Postgraduate Research in Iron and Manganese Ore Resources (PRIMOR) and Tsodilo Resources Ltd. The study sets out to explore the mineralogy and chemistry of XIF in order to determine its origin, constrain the redox conditions in the paleo-basin, assess it in the context of other Neoproterozoic iron-formations and older Archean and Paleoproterozoic iron-formations, and inform metallurgical processing. The mineralogy of XIF consists of magnetite, quartz, amphibole, garnet, biotite and chlorite in decreasing abundance. This mineral assemblage is characteristic of medium grade metamorphosed iron-formations. Algoma and Superior-type BIFs which experienced late-diagenetic and very low-grade metamorphism have a complex mineral assemblage consisting of hematite, magnetite, quartz, and several carbonate (dolomite-ankerite series and siderite) and silicate phases (greenalite, riebeckite and stilpnomelane). The geochemical results show that XIF has higher Mn3O4 and Al2O3 average contents when compared to Algoma and Superior type BIF. The detrital components in XIF correlate with High Field Strength Elements (HFSE) suggesting increased delivery of siliciclastic material during deposition. This trend is comparable to other NIF deposits suggesting a global high input of siliciclastic material into Neoproterozoic paleodepositional environments. This trend is different from Archean and Paleoproterozoic BIF deposits which are close to pure chemical sediments lacking measurable detrital contributions. In the XIF, bulk-rock Mn3O4 and Al2O3 in drillcore SW have higher averages of 2.4 and 2.6 wt. % respectively, compared to the other three cores. The Mn3O4 shows a positive statistical relationship with Co, suggesting that Neoproterozoic oceans and atmosphere were possibly more oxic than in the Archean and Paleoproterozoic. The Mn3O4 shows an antithetic relationship with Fe2O3 suggesting that the paleobasin was chemically heterogeneous in terms of redox conditions, with Fe2O3 depositing presumably in deeper parts removed from a detrital source, and Mn3O4 depositing possibly more proximal to a paleo-shoreline in a shallower setting where there was higher delivery of siliciclastic material from the continent due to correspondingly higher Al2O3 and TiO2 contents. The REE patterns of XIF show positive-sloping trends of depletion in LREE and enrichment in HREE which resemble those of seawater. However, the REE slope becomes a lot flatter and resembles closer the signature of PAAS and adjacent diamictite facies, which agrees with the idea of high siliciclastic input in the paleobasin comparable to other NIF. XIF also appears to lack clear Ce or Eu anomalies. The lack of the former points to the oceans possibly not being oxic enough to drive the fractionation of Ce into Mn oxides like in the modern oceans, or that the Ce behaviour is obscured by the high siliciclastic input in XIF. Similarly, the lack of positive Eu anomaly shows a weak to absent hydrothermal signal into to modern shallow seawater where Fe and Si were sourced, or detritally derived REE contamination. Extensive weathering under hot and humid climate during glacial retreat is shown by the low K2O/Al2O3 ratios and high CIA values ranging from 80-99. Re-glaciation signifies the return of cold and arid and it is represented by high K2O/Al2O3 ratios and low CIA values ranging from 64-78. The previous genetic models of NIF by Klein (1993), Baldwin et al. (2012) and Lechte and Wallace (2015) provide an essential foundation for the development of a XIF genetic model. The genetic model of XIF proposes deposition on an open continental shelf characterized by a steady influx of detrital material. The seawater has been anoxic since the Paleoproterozoic and further induced by basin stagnation due to the ice covering the basin. Two overlapping oxidative stages are assumed for the precipitation of Fe and Mn across lateral redox gradients in the paleobasin. The exact oxidative pathways and mechanisms for the above processes remains unconstrained.
- Full Text:
- Date Issued: 2020
Mineralogy, geochemistry and pebble morphology of the Katberg Formation around Graaff Reinet and East London, Eastern Cape province of South Africa
- Authors: Ndlazi, Nondumiso Zandile
- Date: 2020
- Subjects: Mineralogy|
- Language: English
- Type: Thesis , Masters , MSc (Geology)
- Identifier: http://hdl.handle.net/10353/18631 , vital:42615
- Description: The Katberg Formation forms the upper part of the Tarkastad Subgroup in the Beaufort Group of the main Karoo Supergroup. The Katberg Formation consists of siliciclastic sedimentary rocks mostly dominated by greyish sandstone, red mudstone with minor siltstone occurrences. The Katberg Formation also consists of calcareous and ferruginous concretions that formed during diagenesis. Braided streams deposited the Katberg Formation with a predominantly sand bed load. The Katberg Formation sandstones contain pebbles with no true conglomerates identified in the study area. This study was conducted in the Katberg Formation to understand the mineralogy, geochemistry, and pebble morphology around Graaff Reinet and East London areas. The major and trace elements were analyzed through X-Ray Fluorescence (XRF) to deduce the source rock provenance, tectonic setting, paleo-weathering conditions, climatic conditions, and sediment maturity. The X-Ray Diffraction (XRD) was used to highlight a detailed distribution and variation of mineralogical polymorphs of the minerals present in sandstones and mudstones. The pebble morphology was used to confirm the depositional environment of the Katberg Formation. The use of The bivariate plots of the Maximum Projection Sphericity Index (MPSI) and the Oblate-Prolate Index (OPI) showed that 79 % of pebbles fall in the fluvial environment, whereas 21 % of pebbles fall in the beach environment. A small proportion of beach pebbles within the Katberg Formation suggests that the river reached the marginal marine environment during its flow. The majority of the pebbles yielded a bladed shape with a dominating Sphericity Index symptomatic of fluvial sediments. All the bivariate plots illustrate the fluvial depositional environment for the sediments of the Katberg Formation. Petrographic studies based on the prepared 15 thin sections indicated that the Katberg Formation rocks are dominated by quartz, feldspar, and clay minerals. However, they show more plagioclase feldspar than k-feldspars. The grains are poorly sorted and immature, with irregular grain sizes and shapes. The angularity of clasts indicates that the grains have travelled shorter distances. The abundance of feldspar minerals suggests that the arkose sandstone was derived either from situ or from a short distance. The albitization of plagioclase to illite and the replacement of plagioclase feldspars by calcite and laumontite is very common in the Katberg Formation, which points out deep burial diagenesis. The XRD analysis revealed the occurrence of 14 minerals in the siliciclastic rocks of the Katberg Formation, namely: quartz, albite, clinochlore, muscovite, phlogopite, annite, illite, orthoclase, anorthoclase, laumontite, calcite, and ankerite. Amongst these minerals, albite, clinochlore, muscovite, and phlogopite show variation in crystal forms known as polymorphs. Geochemical analysis of the Katberg Formation sandstones and mudrocks revealed that all samples show a high concentration of SiO2, Al2O3, Fe2O3, K2O, Na2O, CaO, and MgO. The trace elements: TiO2, MnO, P2O5, BaO, SrO, ZrO2, and V2O5 are depleted with values ranging below 1 wt %. The geochemical classification of the Katberg Formation sandstones revealed the origin from wacke and arkose sources. The geochemical diagrams and indices of paleoweathering conditions suggested that the Katberg Formation underwent a moderate degree of chemical weathering. The geochemistry revealed that the sediments were 4 Final Submission of Thesis, Dissertation or Research Report/Project, Conference or Exam Paper deposited during the arid climate conditions. The studied sandstone and mudstone samples pointed an active continental margin and passive margin tectonic setting of the Katberg Formation.
- Full Text:
- Date Issued: 2020
- Authors: Ndlazi, Nondumiso Zandile
- Date: 2020
- Subjects: Mineralogy|
- Language: English
- Type: Thesis , Masters , MSc (Geology)
- Identifier: http://hdl.handle.net/10353/18631 , vital:42615
- Description: The Katberg Formation forms the upper part of the Tarkastad Subgroup in the Beaufort Group of the main Karoo Supergroup. The Katberg Formation consists of siliciclastic sedimentary rocks mostly dominated by greyish sandstone, red mudstone with minor siltstone occurrences. The Katberg Formation also consists of calcareous and ferruginous concretions that formed during diagenesis. Braided streams deposited the Katberg Formation with a predominantly sand bed load. The Katberg Formation sandstones contain pebbles with no true conglomerates identified in the study area. This study was conducted in the Katberg Formation to understand the mineralogy, geochemistry, and pebble morphology around Graaff Reinet and East London areas. The major and trace elements were analyzed through X-Ray Fluorescence (XRF) to deduce the source rock provenance, tectonic setting, paleo-weathering conditions, climatic conditions, and sediment maturity. The X-Ray Diffraction (XRD) was used to highlight a detailed distribution and variation of mineralogical polymorphs of the minerals present in sandstones and mudstones. The pebble morphology was used to confirm the depositional environment of the Katberg Formation. The use of The bivariate plots of the Maximum Projection Sphericity Index (MPSI) and the Oblate-Prolate Index (OPI) showed that 79 % of pebbles fall in the fluvial environment, whereas 21 % of pebbles fall in the beach environment. A small proportion of beach pebbles within the Katberg Formation suggests that the river reached the marginal marine environment during its flow. The majority of the pebbles yielded a bladed shape with a dominating Sphericity Index symptomatic of fluvial sediments. All the bivariate plots illustrate the fluvial depositional environment for the sediments of the Katberg Formation. Petrographic studies based on the prepared 15 thin sections indicated that the Katberg Formation rocks are dominated by quartz, feldspar, and clay minerals. However, they show more plagioclase feldspar than k-feldspars. The grains are poorly sorted and immature, with irregular grain sizes and shapes. The angularity of clasts indicates that the grains have travelled shorter distances. The abundance of feldspar minerals suggests that the arkose sandstone was derived either from situ or from a short distance. The albitization of plagioclase to illite and the replacement of plagioclase feldspars by calcite and laumontite is very common in the Katberg Formation, which points out deep burial diagenesis. The XRD analysis revealed the occurrence of 14 minerals in the siliciclastic rocks of the Katberg Formation, namely: quartz, albite, clinochlore, muscovite, phlogopite, annite, illite, orthoclase, anorthoclase, laumontite, calcite, and ankerite. Amongst these minerals, albite, clinochlore, muscovite, and phlogopite show variation in crystal forms known as polymorphs. Geochemical analysis of the Katberg Formation sandstones and mudrocks revealed that all samples show a high concentration of SiO2, Al2O3, Fe2O3, K2O, Na2O, CaO, and MgO. The trace elements: TiO2, MnO, P2O5, BaO, SrO, ZrO2, and V2O5 are depleted with values ranging below 1 wt %. The geochemical classification of the Katberg Formation sandstones revealed the origin from wacke and arkose sources. The geochemical diagrams and indices of paleoweathering conditions suggested that the Katberg Formation underwent a moderate degree of chemical weathering. The geochemistry revealed that the sediments were 4 Final Submission of Thesis, Dissertation or Research Report/Project, Conference or Exam Paper deposited during the arid climate conditions. The studied sandstone and mudstone samples pointed an active continental margin and passive margin tectonic setting of the Katberg Formation.
- Full Text:
- Date Issued: 2020
Misalignments in assessments: Using Semantics to reveal weaknesses
- Rootman-le Grange, Ilsa, Blackie, Margaret A L
- Authors: Rootman-le Grange, Ilsa , Blackie, Margaret A L
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/445837 , vital:74436 , ISBN 9781003028215 , https://www.taylorfrancis.com/chapters/edit/10.4324/9781003028215-5/misalignments-assessments-ilse-rootman-le-grange-margaret-blackie
- Description: Creating cumulative learning opportunities is a key challenge in all physical sciences. This is particularly the case for introductory university modules that are mandatory for enrolment in more specialized courses. Students are expected to accumulate a foundational base of knowledge, and build on and apply this knowledge to different contexts in later courses. Since assessment is a core learning opportunity, it is important to consider the roles it can play in addressing this challenge. This chapter provides an example of how LCT can be used to evaluate and inform the quality of assessments. Using the example of a chemistry assessment in an introductory course offered to first-year health science students, we draw on LCT concepts of ‘semantic gravity’ and ‘semantic density’ to show how the ability to shift between abstract and highly-condensed meanings and relatively context-dependent meanings in student assessments is indicative of cumulative knowledge-building. Furthermore, analysis reveals how some assessments are not well suited to produce these learning outcomes. As such, the chapter provides insights into how LCT can inform the design of assessments in order to encourage the development of cumulative learning in similar contexts.
- Full Text:
- Date Issued: 2020
- Authors: Rootman-le Grange, Ilsa , Blackie, Margaret A L
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/445837 , vital:74436 , ISBN 9781003028215 , https://www.taylorfrancis.com/chapters/edit/10.4324/9781003028215-5/misalignments-assessments-ilse-rootman-le-grange-margaret-blackie
- Description: Creating cumulative learning opportunities is a key challenge in all physical sciences. This is particularly the case for introductory university modules that are mandatory for enrolment in more specialized courses. Students are expected to accumulate a foundational base of knowledge, and build on and apply this knowledge to different contexts in later courses. Since assessment is a core learning opportunity, it is important to consider the roles it can play in addressing this challenge. This chapter provides an example of how LCT can be used to evaluate and inform the quality of assessments. Using the example of a chemistry assessment in an introductory course offered to first-year health science students, we draw on LCT concepts of ‘semantic gravity’ and ‘semantic density’ to show how the ability to shift between abstract and highly-condensed meanings and relatively context-dependent meanings in student assessments is indicative of cumulative knowledge-building. Furthermore, analysis reveals how some assessments are not well suited to produce these learning outcomes. As such, the chapter provides insights into how LCT can inform the design of assessments in order to encourage the development of cumulative learning in similar contexts.
- Full Text:
- Date Issued: 2020
Misconceptions and misapplications of student-centered approaches
- Authors: McKenna, Sioux , Quinn, Lynn
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/453507 , vital:75259 , ISBN 9780429259371 , https://www.taylorfrancis.com/chapters/edit/10.4324/9780429259371-8/misconceptions-misapplications-student-centered-approaches-sioux-mckenna-lynn-quinn
- Description: A 1967 cartoon strip by Bud Blake shows a young boy, Tiger, telling his friend that he has taught his dog, Stripe, to whistle. “I don’t hear him whistling,” says the friend. Tiger explains “I said I taught him. I didn’t say he learned it.” Understanding education in terms of what it is that teachers do at the expense of a focus on how students learn has long been criticized. In 1916, Dewey was calling for more democratic approaches to education which took the student’s context into account. In 1968, Freire called for a major shift away from the “banking model” of education to one that recognized the student’s role in co-constructing knowledge. Despite the long history of such calls, transmission modes of teaching endure. It is thus unsurprising that calls for student-centered learning (SCL) are widespread.
- Full Text:
- Date Issued: 2020
- Authors: McKenna, Sioux , Quinn, Lynn
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/453507 , vital:75259 , ISBN 9780429259371 , https://www.taylorfrancis.com/chapters/edit/10.4324/9780429259371-8/misconceptions-misapplications-student-centered-approaches-sioux-mckenna-lynn-quinn
- Description: A 1967 cartoon strip by Bud Blake shows a young boy, Tiger, telling his friend that he has taught his dog, Stripe, to whistle. “I don’t hear him whistling,” says the friend. Tiger explains “I said I taught him. I didn’t say he learned it.” Understanding education in terms of what it is that teachers do at the expense of a focus on how students learn has long been criticized. In 1916, Dewey was calling for more democratic approaches to education which took the student’s context into account. In 1968, Freire called for a major shift away from the “banking model” of education to one that recognized the student’s role in co-constructing knowledge. Despite the long history of such calls, transmission modes of teaching endure. It is thus unsurprising that calls for student-centered learning (SCL) are widespread.
- Full Text:
- Date Issued: 2020
Mobilising the indigenous practice of making Oshikundu using an inquiry-based approach to support Grade 8 Life Science teachers in mediating learning of enzymes
- Shinana, Ester Ndakondja Lineekela
- Authors: Shinana, Ester Ndakondja Lineekela
- Date: 2020
- Subjects: Education, Secondary -- Namibia , Ethnoscience -- Namibia , Fermented beverages -- Namibia , Science -- Study and teaching (Secondary) -- Namibia , Enzymes -- Study and teaching (Secondary) -- Namibia , Ethnoscience -- Study and teaching (Secondary) -- Namibia
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/163615 , vital:41061
- Description: The Namibian curriculum encourages Life Science teachers to integrate indigenous knowledge into their science lessons. Additionally, it also encourages teachers to promote scientific inquiry in their science classrooms. However, it is not clear how Life Science teachers should go about doing this. As a result, science is taught in decontextualised ways and inquiry-based methods are neglected. It is against this background that this study sought to mobilise the indigenous practice of making oshikundu to mediate learning of enzymes and to promote inquiry-based methods. Essentially, an attempt was made to mediate the learning of enzymes through inquiry-based methods using, in particular, the Predict-Explain-Explore-Observe-Explain (PEEOE)approach.The approach entails learners making predictions and providing explanations for their predictions before they do their observations. The study employed a qualitative case study approach underpinned by an interpretive paradigm. It was conducted at two schools in the Omusati Region in Namibia and three Life Science teachers (two from one school and one from a different school) participated in this study.A variety of data gathering techniques such as document analysis, workshop discussions, participatory observation, and journal reflections were used to gather data and for triangulation purposes. A thematic approach to data analysis was adopted and data analysis and interpretation we redone inductively using Vygotsky’s socio-cultural theory and Shulman’s Pedagogical Content Kno Knowledge (TSPCK) model was used as the analytical framework to identify and improve the quality of Life Science teachers’ PCK in the topic of enzyme s in particular. Findings from this study revealed that some teachers had a narrow understanding of the concept of scientific inquiry, whereas some demonstrated a better understanding of the concept and how it is used in Life Science classrooms. The findings also revealed that the understanding of the teachers of an inquiry approach and how they understood science should be taught, further influenced their practice ; this was in addition to resource constraints. Furthermore, it was also established that some teachers did not include the concept of enzymes in their teaching. The workshop intervention equipped teachers with the knowledge on an inquiry approach and how to promote scientific inquiry skills in their classrooms. Likewise, the practical demonstration of making oshikundu also equipped the teachers with the knowledge of enzymes and together with the PEEOE approach, how to teach enzyme s using an inquiry approach. Teachers experienced challenges, as they had to use their creative, critical thinking and reasoning skills in order to identify the scientific concepts from the practical demonstration of oshikundu. The study suggests that there is a need for professional development programmes focusing specifically on supporting in-service science teachers’ understanding of inquiry and how to use the inquiry-based approach in their classrooms. Equally, the pre-service science teachers need such preparations during their training. Furthermore, the study also presents that there is a need to engage both pre-service and in-service teachers deeply with the new content of the Life Science syllabus.
- Full Text:
- Date Issued: 2020
- Authors: Shinana, Ester Ndakondja Lineekela
- Date: 2020
- Subjects: Education, Secondary -- Namibia , Ethnoscience -- Namibia , Fermented beverages -- Namibia , Science -- Study and teaching (Secondary) -- Namibia , Enzymes -- Study and teaching (Secondary) -- Namibia , Ethnoscience -- Study and teaching (Secondary) -- Namibia
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/163615 , vital:41061
- Description: The Namibian curriculum encourages Life Science teachers to integrate indigenous knowledge into their science lessons. Additionally, it also encourages teachers to promote scientific inquiry in their science classrooms. However, it is not clear how Life Science teachers should go about doing this. As a result, science is taught in decontextualised ways and inquiry-based methods are neglected. It is against this background that this study sought to mobilise the indigenous practice of making oshikundu to mediate learning of enzymes and to promote inquiry-based methods. Essentially, an attempt was made to mediate the learning of enzymes through inquiry-based methods using, in particular, the Predict-Explain-Explore-Observe-Explain (PEEOE)approach.The approach entails learners making predictions and providing explanations for their predictions before they do their observations. The study employed a qualitative case study approach underpinned by an interpretive paradigm. It was conducted at two schools in the Omusati Region in Namibia and three Life Science teachers (two from one school and one from a different school) participated in this study.A variety of data gathering techniques such as document analysis, workshop discussions, participatory observation, and journal reflections were used to gather data and for triangulation purposes. A thematic approach to data analysis was adopted and data analysis and interpretation we redone inductively using Vygotsky’s socio-cultural theory and Shulman’s Pedagogical Content Kno Knowledge (TSPCK) model was used as the analytical framework to identify and improve the quality of Life Science teachers’ PCK in the topic of enzyme s in particular. Findings from this study revealed that some teachers had a narrow understanding of the concept of scientific inquiry, whereas some demonstrated a better understanding of the concept and how it is used in Life Science classrooms. The findings also revealed that the understanding of the teachers of an inquiry approach and how they understood science should be taught, further influenced their practice ; this was in addition to resource constraints. Furthermore, it was also established that some teachers did not include the concept of enzymes in their teaching. The workshop intervention equipped teachers with the knowledge on an inquiry approach and how to promote scientific inquiry skills in their classrooms. Likewise, the practical demonstration of making oshikundu also equipped the teachers with the knowledge of enzymes and together with the PEEOE approach, how to teach enzyme s using an inquiry approach. Teachers experienced challenges, as they had to use their creative, critical thinking and reasoning skills in order to identify the scientific concepts from the practical demonstration of oshikundu. The study suggests that there is a need for professional development programmes focusing specifically on supporting in-service science teachers’ understanding of inquiry and how to use the inquiry-based approach in their classrooms. Equally, the pre-service science teachers need such preparations during their training. Furthermore, the study also presents that there is a need to engage both pre-service and in-service teachers deeply with the new content of the Life Science syllabus.
- Full Text:
- Date Issued: 2020
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
Modern supratidal microbialites fed by groundwater: functional drivers, value and trajectories
- Rishworth, Gavin M, Dodd, Carla, Perissinotto, Renzo, Bornman, Thomas G, Adams, Janine B, Anderson, Callum R, Cawthra, Hayley C, Dorrington, Hayley C, du Toit, Hendrik, Edworthy, Carla, Gibb, Ross-Lynne A, Human, Lucienne R D, Isemonger, Eric W, Lemley, David A, Miranda, Nelson A F, Peer, Nasreen, Raw, Jacqueline L, Smith, Alan M, Steyn, Paul-Pierre, Strydom, Nadine A, Teske, Peter R, Welman, Peter R
- Authors: Rishworth, Gavin M , Dodd, Carla , Perissinotto, Renzo , Bornman, Thomas G , Adams, Janine B , Anderson, Callum R , Cawthra, Hayley C , Dorrington, Hayley C , du Toit, Hendrik , Edworthy, Carla , Gibb, Ross-Lynne A , Human, Lucienne R D , Isemonger, Eric W , Lemley, David A , Miranda, Nelson A F , Peer, Nasreen , Raw, Jacqueline L , Smith, Alan M , Steyn, Paul-Pierre , Strydom, Nadine A , Teske, Peter R , Welman, Peter R
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426008 , vital:72306 , xlink:href="https://doi.org/10.1016/j.earscirev.2020.103364"
- Description: Microbial mats were the dominant habitat type in shallow marine environments between the Palaeoarchean and Phanerozoic. Many of these (termed ‘microbialites’) calcified as they grew but such lithified mats are rare along modern coasts for reasons such as unsuitable water chemistry, destructive metazoan influences and competition with other reef-builders such as corals or macroalgae. Nonetheless, extant microbialites occur in unique coastal ecosystems such as the Exuma Cays, Bahamas or Lake Clifton and Hamelin Pool, Australia, where limitations such as calcium carbonate availability or destructive bioturbation are diminished. Along the coast of South Africa, extensive distributions of living microbialites (including layered stromatolites) have been discovered and described since the early 2000s. Unlike the Bahamian and Australian ecosystems, the South African microbialites form exclusively in the supratidal coastal zone at the convergence of emergent groundwater seepage. Similar systems were documented subsequently in southwestern Australia, Northern Ireland and the Scottish Hebrides, as recently as 2018, revealing that supratidal microbialites have a global distribution. This review uses the best-studied formations to contextualise formative drivers and processes of these supratidal ecosystems and highlight their geological, ecological and societal relevance.
- Full Text:
- Date Issued: 2020
- Authors: Rishworth, Gavin M , Dodd, Carla , Perissinotto, Renzo , Bornman, Thomas G , Adams, Janine B , Anderson, Callum R , Cawthra, Hayley C , Dorrington, Hayley C , du Toit, Hendrik , Edworthy, Carla , Gibb, Ross-Lynne A , Human, Lucienne R D , Isemonger, Eric W , Lemley, David A , Miranda, Nelson A F , Peer, Nasreen , Raw, Jacqueline L , Smith, Alan M , Steyn, Paul-Pierre , Strydom, Nadine A , Teske, Peter R , Welman, Peter R
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426008 , vital:72306 , xlink:href="https://doi.org/10.1016/j.earscirev.2020.103364"
- Description: Microbial mats were the dominant habitat type in shallow marine environments between the Palaeoarchean and Phanerozoic. Many of these (termed ‘microbialites’) calcified as they grew but such lithified mats are rare along modern coasts for reasons such as unsuitable water chemistry, destructive metazoan influences and competition with other reef-builders such as corals or macroalgae. Nonetheless, extant microbialites occur in unique coastal ecosystems such as the Exuma Cays, Bahamas or Lake Clifton and Hamelin Pool, Australia, where limitations such as calcium carbonate availability or destructive bioturbation are diminished. Along the coast of South Africa, extensive distributions of living microbialites (including layered stromatolites) have been discovered and described since the early 2000s. Unlike the Bahamian and Australian ecosystems, the South African microbialites form exclusively in the supratidal coastal zone at the convergence of emergent groundwater seepage. Similar systems were documented subsequently in southwestern Australia, Northern Ireland and the Scottish Hebrides, as recently as 2018, revealing that supratidal microbialites have a global distribution. This review uses the best-studied formations to contextualise formative drivers and processes of these supratidal ecosystems and highlight their geological, ecological and societal relevance.
- Full Text:
- Date Issued: 2020
Molecular and morphological approaches reveal hidden diversity in the genus hippopotamyrus pappenheim, 1906 (teleostei: mormyridae) in southern Africa
- Authors: Mutizwa, Tadiwa, Isaac
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164546 , vital:41128
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Department of Icthyology and Fisheries Science, 2020
- Full Text:
- Date Issued: 2020
- Authors: Mutizwa, Tadiwa, Isaac
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164546 , vital:41128
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Department of Icthyology and Fisheries Science, 2020
- Full Text:
- Date Issued: 2020
Molecular simulations of potential agents and targets of Alzheimer’s disease
- Authors: Carlisle, Tanya
- Date: 2020
- Subjects: Alzheimer's disease -- Treatment , Alzheimer's disease -- Molecular aspects , Amyloid beta-protein precurs , Amyloid beta-protein
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/140025 , vital:37825
- Description: The World Alzheimer Report statedin 2016 that approximately 46.8 million people were living with dementia and this figure is expected to triple by 2050. Alzheimer’s Disease was discovered to be a precursor to dementia in 1976 and since then efforts to understand Alzheimer’s have been prioritized. To date, there are very few effective forms of treatment for Alzheimer’s, many are known to offer only mild calming of the symptoms and have side effects such as diarrhea, nausea, loss of appetite and sleep disturbances. This has been due to lack of understanding on how Alzheimer’s is caused. With the two main hallmarks of the disease now being more understood it has opened the doorway into the discovery of new treatments for this disease. This study focuses on the hallmark involving the aggregation of the β-amyloid protein to form plaques surrounding the neurons of the brain. Copper, Zinc and Iron have also been found in high concentrations in and surrounding these plaques. This study focused on the screening of the South African Natural Compound database (SANCDB) to discover hits that have potential destabilizing action against the Beta-amyloid aggregate. If one of these compounds could prove to have destabilizing action on the aggregate it could open the doorway to new potential forms of treatment. Over 700 SANCDB compounds were docked, and the top hits were taken to molecular dynamics to further study the interactions of the compounds and the aggregate. However, the hits identified had strong binding to the aggregate causing it to become stable instead of the desired effect of destabilizing the structure. This information, however, does not rule out the possibility of these compounds preventing the formation of the aggregates. Further, interactions of copper with β-amyloid and copper were determined by solubilizing the aggregate and introducing copper ions in a dynamics simulation. Possible interactions between copper and the methionine residues were visualised.
- Full Text:
- Date Issued: 2020
- Authors: Carlisle, Tanya
- Date: 2020
- Subjects: Alzheimer's disease -- Treatment , Alzheimer's disease -- Molecular aspects , Amyloid beta-protein precurs , Amyloid beta-protein
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/140025 , vital:37825
- Description: The World Alzheimer Report statedin 2016 that approximately 46.8 million people were living with dementia and this figure is expected to triple by 2050. Alzheimer’s Disease was discovered to be a precursor to dementia in 1976 and since then efforts to understand Alzheimer’s have been prioritized. To date, there are very few effective forms of treatment for Alzheimer’s, many are known to offer only mild calming of the symptoms and have side effects such as diarrhea, nausea, loss of appetite and sleep disturbances. This has been due to lack of understanding on how Alzheimer’s is caused. With the two main hallmarks of the disease now being more understood it has opened the doorway into the discovery of new treatments for this disease. This study focuses on the hallmark involving the aggregation of the β-amyloid protein to form plaques surrounding the neurons of the brain. Copper, Zinc and Iron have also been found in high concentrations in and surrounding these plaques. This study focused on the screening of the South African Natural Compound database (SANCDB) to discover hits that have potential destabilizing action against the Beta-amyloid aggregate. If one of these compounds could prove to have destabilizing action on the aggregate it could open the doorway to new potential forms of treatment. Over 700 SANCDB compounds were docked, and the top hits were taken to molecular dynamics to further study the interactions of the compounds and the aggregate. However, the hits identified had strong binding to the aggregate causing it to become stable instead of the desired effect of destabilizing the structure. This information, however, does not rule out the possibility of these compounds preventing the formation of the aggregates. Further, interactions of copper with β-amyloid and copper were determined by solubilizing the aggregate and introducing copper ions in a dynamics simulation. Possible interactions between copper and the methionine residues were visualised.
- Full Text:
- Date Issued: 2020
Molecular simulations of potential agents and targets of Alzheimer’s disease
- Authors: Joli, Luxolo
- Date: 2020
- Subjects: Alzheimer's disease -- Chemotherapy , Alzheimer's disease -- Treatment , Ligands (Biochemistry) , Proteins -- Chemistry , Molecular dynamics -- Simulation methods
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/146411 , vital:38523
- Description: Alzheimer's Disease (AD) is a neurodegenerative brain disorder that was first discovered in 1901 by Dr Aloïs Alzheimer and was later reported publicly in 1906. The German doctor had a 51-yearold woman patient called Auguste Deter, who was suffering from a rare brain disorder with early signs of memory loss and cognition. Alzheimer's Disease is the most common type of dementia that affects people with the age of 65 years and older. There is no single known cause of Alzheimer’s disease however, amyloid β-peptide (Aβ1–40/42) was found to be at the centre of AD pathogenesis and this connection was referred as “amyloid hypothesis”. It is suspected that an accumulation of amyloid β-peptide is a major contributor to neuronal dysfunction and degeneration. Alzheimer’s disease is complex and therefore, currently there is no medication available that treats the disease. However, there are approaches that focus on helping people maintain mental function, manage behavioral symptoms, and slow down the symptoms of disease. According to South Africa’s 2011 census, there are approximately 2.2 million people in South Africa with some form of dementia and therefore there is a need to find a treatment for the disease. This study aims to find agents and targets of Alzheimer’s Disease by using different computational techniques such as molecular modelling. The study will use compounds from the South African Compounds Database (SANCDB) and the following therapeutic targets α-, β- and γ-secretase, acetylcholinesterase, tau protein and neprilysin. A successful High-throughput Virtual Screening (HTVS) study to determine lead compounds was performed using a computational program called KNIME. Molecular docking was achieved with GLIDE as it allows for exhaustive ligand flexibility. The docking calculations were carried out using the high level of precision XP (extra precision) for enhanced docking accuracy. The binding affinities (docking scores) for the best bound ligands obtained from docking were in the order of -5 kcal/mol or less. The ligandSANC00370 was the best binding ligand against the protein 1J1C_B and had the best binding energy of -13.94 kcal/mol compared to others. The receptor-ligand complexes were analyzed using the interaction diagrams obtained from the Discovery Studio Visualizer and Maestro programs. Molecular Dynamics simulations were performed on the complexes obtained from docking to help in optimizing their interactions. The simulations were performed using the Desmond tool with the OPLS3 force field. 100 ns simulations were performed for six systems with the best docking score results epresenting each of the therapeutic targets and for the other complex systems, 50 ns simulations were performed. The Desmond simulations were analyzed using the Simulations Interaction Diagrams such as PL-RMSD, L-RMSF, P-RMSF, L-Torsions, P-SSE, LP-Contacts and L-Properties. Maestro was used to visualize the stability of the ligands in the active site during the simulation. All 13 Desmond simulations were successful however, there were 9 simulations which produced satisfactory results while the others were nsatisfactory. Based on the molecular docking and Molecular Dynamics results of this study, 9 potential targets and 6 potential agents were obtained successfully and can be studied further as therapeutics for Alzheimer’s Disease.
- Full Text:
- Date Issued: 2020
- Authors: Joli, Luxolo
- Date: 2020
- Subjects: Alzheimer's disease -- Chemotherapy , Alzheimer's disease -- Treatment , Ligands (Biochemistry) , Proteins -- Chemistry , Molecular dynamics -- Simulation methods
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/146411 , vital:38523
- Description: Alzheimer's Disease (AD) is a neurodegenerative brain disorder that was first discovered in 1901 by Dr Aloïs Alzheimer and was later reported publicly in 1906. The German doctor had a 51-yearold woman patient called Auguste Deter, who was suffering from a rare brain disorder with early signs of memory loss and cognition. Alzheimer's Disease is the most common type of dementia that affects people with the age of 65 years and older. There is no single known cause of Alzheimer’s disease however, amyloid β-peptide (Aβ1–40/42) was found to be at the centre of AD pathogenesis and this connection was referred as “amyloid hypothesis”. It is suspected that an accumulation of amyloid β-peptide is a major contributor to neuronal dysfunction and degeneration. Alzheimer’s disease is complex and therefore, currently there is no medication available that treats the disease. However, there are approaches that focus on helping people maintain mental function, manage behavioral symptoms, and slow down the symptoms of disease. According to South Africa’s 2011 census, there are approximately 2.2 million people in South Africa with some form of dementia and therefore there is a need to find a treatment for the disease. This study aims to find agents and targets of Alzheimer’s Disease by using different computational techniques such as molecular modelling. The study will use compounds from the South African Compounds Database (SANCDB) and the following therapeutic targets α-, β- and γ-secretase, acetylcholinesterase, tau protein and neprilysin. A successful High-throughput Virtual Screening (HTVS) study to determine lead compounds was performed using a computational program called KNIME. Molecular docking was achieved with GLIDE as it allows for exhaustive ligand flexibility. The docking calculations were carried out using the high level of precision XP (extra precision) for enhanced docking accuracy. The binding affinities (docking scores) for the best bound ligands obtained from docking were in the order of -5 kcal/mol or less. The ligandSANC00370 was the best binding ligand against the protein 1J1C_B and had the best binding energy of -13.94 kcal/mol compared to others. The receptor-ligand complexes were analyzed using the interaction diagrams obtained from the Discovery Studio Visualizer and Maestro programs. Molecular Dynamics simulations were performed on the complexes obtained from docking to help in optimizing their interactions. The simulations were performed using the Desmond tool with the OPLS3 force field. 100 ns simulations were performed for six systems with the best docking score results epresenting each of the therapeutic targets and for the other complex systems, 50 ns simulations were performed. The Desmond simulations were analyzed using the Simulations Interaction Diagrams such as PL-RMSD, L-RMSF, P-RMSF, L-Torsions, P-SSE, LP-Contacts and L-Properties. Maestro was used to visualize the stability of the ligands in the active site during the simulation. All 13 Desmond simulations were successful however, there were 9 simulations which produced satisfactory results while the others were nsatisfactory. Based on the molecular docking and Molecular Dynamics results of this study, 9 potential targets and 6 potential agents were obtained successfully and can be studied further as therapeutics for Alzheimer’s Disease.
- Full Text:
- Date Issued: 2020
Monitoring and evaluation in a changing world: A Southern African perspective on the skills needed for a new approach
- Rosenberg, Eureta, Kotschy, Karen
- Authors: Rosenberg, Eureta , Kotschy, Karen
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370711 , vital:66369 , xlink:href="https://doi.org/ 10.4102/aej.v8i1.472"
- Description: Background: As science and modern technology have brought many advances, we have also come to overshoot planetary boundaries, while still falling short of development goals to eradicate poverty and inequality. A growing recognition of the complexity of development problems and contexts calls for new framings, including a new approach to monitoring and evaluation (M and E) as one of the mechanisms by which modern societies aim to steer towards a more sustainable future. New approaches to M and E mean new skills for the M and E practitioner. Objectives: This article proposed a framing for M and E skills, comprising of technical, relational and transformational (T-R-T) competences. Method: Adapted from the literature, this competence framework was tested in a broader learning needs assessment and then applied retrospectively to author’s experience in developmental evaluations in complex social–ecological contexts in southern Africa. Results: The emerging insights were that not only technical competence is needed, but also relational competence that goes beyond interpersonal skills, to enable the production and uptake of evaluation findings. In addition, the limitations of mainstream M and E methods in the face of complexity seemed to create a need for ‘transformational’ competence, which included evaluators’ ability to develop credible M and E alternatives. Conclusion: The T-R-T framework helped to advance the notions of ‘hard’ and ‘soft’ skills and expanded on existing M and E competence frameworks. Recommendations included a call for innovative educational and professional development approaches to develop relational and transformational competencies, in addition to training for technical competence.
- Full Text:
- Date Issued: 2020
- Authors: Rosenberg, Eureta , Kotschy, Karen
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370711 , vital:66369 , xlink:href="https://doi.org/ 10.4102/aej.v8i1.472"
- Description: Background: As science and modern technology have brought many advances, we have also come to overshoot planetary boundaries, while still falling short of development goals to eradicate poverty and inequality. A growing recognition of the complexity of development problems and contexts calls for new framings, including a new approach to monitoring and evaluation (M and E) as one of the mechanisms by which modern societies aim to steer towards a more sustainable future. New approaches to M and E mean new skills for the M and E practitioner. Objectives: This article proposed a framing for M and E skills, comprising of technical, relational and transformational (T-R-T) competences. Method: Adapted from the literature, this competence framework was tested in a broader learning needs assessment and then applied retrospectively to author’s experience in developmental evaluations in complex social–ecological contexts in southern Africa. Results: The emerging insights were that not only technical competence is needed, but also relational competence that goes beyond interpersonal skills, to enable the production and uptake of evaluation findings. In addition, the limitations of mainstream M and E methods in the face of complexity seemed to create a need for ‘transformational’ competence, which included evaluators’ ability to develop credible M and E alternatives. Conclusion: The T-R-T framework helped to advance the notions of ‘hard’ and ‘soft’ skills and expanded on existing M and E competence frameworks. Recommendations included a call for innovative educational and professional development approaches to develop relational and transformational competencies, in addition to training for technical competence.
- Full Text:
- Date Issued: 2020