Hermeneutic and empirical analyses of graphically inspired metamathematics that reflect critical consciousness within perspectives of personal and social justice
- Authors: Van Jaarsveld, Pieter Paul
- Date: 2007
- Subjects: Mathematics -- Study and teaching -- South Africa Mathematics -- Study and teaching -- Social aspects -- South Africa Algorithms -- Study and teaching -- South Africa Critical pedagogy Metacognition Hermeneutics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1842 , http://hdl.handle.net/10962/d1004376
- Description: My involvement with mathematics education amongst township educators and learners over the past seven years has highlighted the absence of sustained meaning and meaning making of mathematical concepts. It appears though that this instrumental rather than relational understanding of FET mathematics is not unique to township learners but is encountered amongst learners of all socio-economic classes and is representative of many FET mathematics learners. Given that the language of learning and teaching is a major contributory factor in the South African education system, it appears that the language of mathematics itself is a greater exacerbating factor for many learners of mathematics. The exclusive algorithmic approach to classroom mathematics further seems to alienate many learners from the essence of the meaning of mathematical tasks. This research undertakes to determine whether metateaching and metalearning as forerunners to metacognition facilitates the acquisition of the sustained meaning of mathematical concepts. Metateaching and metalearning refer to the acute and deliberate awareness by educator and learner as to what constitutes concepts. Teaching and learning therefore presupposes the deconstruction of concepts into its subsumed derivative roots. It also assumes an awareness of the tacit degrees of abstraction that characterise tasks and the content of tasks. This in turn has implications for the educator's adopted sequence of topics for instruction. Metacognition implies awareness on the part of the learner (and educator) as to how material is learned and a further awareness as to how that learning can be sustained. Whether we ascribe meaningful learning to radical or social constructivism, or to associationist didactive approaches, or a combination of these, we are making assumptions about how learners acquire and sustain mathematical meaning because mathematics is, by and large a symbolic language often devoid of affective connotation. Furthermore our assessments of learners' tasks amount to clinical corrections of austere formulae wrapped in algorithmic procedures which manifest nothing of a learner's experience of mathematics or the deeper understanding (or misunderstandings) which characterise a learning and/or assessment episode. To this end the research design of this interpretive case study requires learners to expound in textual accounts their thoughts as they describe the evolution of a mathematical process as they approach a solution and eventually interpret it. The textual account exposes the concept definition for what it really is in a learner's understanding of it and it is the expressiveness of language that indicates whether the understanding of a learner is approaching the concept image. The textual accounts vary in richness in terms of mathematical register and this in turn reflects the conceptual depth. The mechanism which seems to promote the conversion from concept definition to concept image is the graphical representation of the mathematical task or procedure, possibly because of its greater concreteness as opposed to the abstraction of its algebraic form.
- Full Text:
- Date Issued: 2007
- Authors: Van Jaarsveld, Pieter Paul
- Date: 2007
- Subjects: Mathematics -- Study and teaching -- South Africa Mathematics -- Study and teaching -- Social aspects -- South Africa Algorithms -- Study and teaching -- South Africa Critical pedagogy Metacognition Hermeneutics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1842 , http://hdl.handle.net/10962/d1004376
- Description: My involvement with mathematics education amongst township educators and learners over the past seven years has highlighted the absence of sustained meaning and meaning making of mathematical concepts. It appears though that this instrumental rather than relational understanding of FET mathematics is not unique to township learners but is encountered amongst learners of all socio-economic classes and is representative of many FET mathematics learners. Given that the language of learning and teaching is a major contributory factor in the South African education system, it appears that the language of mathematics itself is a greater exacerbating factor for many learners of mathematics. The exclusive algorithmic approach to classroom mathematics further seems to alienate many learners from the essence of the meaning of mathematical tasks. This research undertakes to determine whether metateaching and metalearning as forerunners to metacognition facilitates the acquisition of the sustained meaning of mathematical concepts. Metateaching and metalearning refer to the acute and deliberate awareness by educator and learner as to what constitutes concepts. Teaching and learning therefore presupposes the deconstruction of concepts into its subsumed derivative roots. It also assumes an awareness of the tacit degrees of abstraction that characterise tasks and the content of tasks. This in turn has implications for the educator's adopted sequence of topics for instruction. Metacognition implies awareness on the part of the learner (and educator) as to how material is learned and a further awareness as to how that learning can be sustained. Whether we ascribe meaningful learning to radical or social constructivism, or to associationist didactive approaches, or a combination of these, we are making assumptions about how learners acquire and sustain mathematical meaning because mathematics is, by and large a symbolic language often devoid of affective connotation. Furthermore our assessments of learners' tasks amount to clinical corrections of austere formulae wrapped in algorithmic procedures which manifest nothing of a learner's experience of mathematics or the deeper understanding (or misunderstandings) which characterise a learning and/or assessment episode. To this end the research design of this interpretive case study requires learners to expound in textual accounts their thoughts as they describe the evolution of a mathematical process as they approach a solution and eventually interpret it. The textual account exposes the concept definition for what it really is in a learner's understanding of it and it is the expressiveness of language that indicates whether the understanding of a learner is approaching the concept image. The textual accounts vary in richness in terms of mathematical register and this in turn reflects the conceptual depth. The mechanism which seems to promote the conversion from concept definition to concept image is the graphical representation of the mathematical task or procedure, possibly because of its greater concreteness as opposed to the abstraction of its algebraic form.
- Full Text:
- Date Issued: 2007
Collaborative research with traditional African health practitioners of the Nelson Mandela Metropole : antimicrobial, anticancer and anti-diabetic activities of five medicinal plants
- Authors: Van Huyssteen, Mea
- Date: 2007
- Subjects: Medicinal plants -- South Africa -- Port Elizabeth , Healers -- South Africa -- Port Elizabeth , Anti-infective agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10148 , http://hdl.handle.net/10948/663 , Medicinal plants -- South Africa -- Port Elizabeth , Healers -- South Africa -- Port Elizabeth , Anti-infective agents
- Description: The promotion and development of indigenous knowledge pertaining to the traditional African healing system is one of the prime objectives set out by the South African government. Despite excellent research opportunities and funding, the biggest problem with ethnopharmacological research is a lack of interaction with indigenous communities, which tends to dilute the benefits this research has to offer these communities. The primary aim of this study was thus to promote the traditional African healing system through collaborative medicinal plant research with local traditional health practitioners. The research collaboration aimed to validate some biological activities of traditional remedies used by collaborating traditional health practitioners and ensured interactive sessions where scientific literature, research practices, findings and relevant legislation were discussed and debated. The joint development of a medicinal garden was a valuable tool in realising these goals. Aqueous and ethanol extracts of Bulbine frutescens, Ornithogalum longibracteatum, Ruta graveolens, Tarchonanthus camphoratus and Tulbaghia violacea were selected for antimicrobial, anticancer and anti-diabetic screening, because of their sustainable utilisation potential. The ethanol extract of T. violacea produced the best antimicrobial activity on Bacillus subtilis (100% growth inhibition) and Candida albicans (89% growth inhibition) at 250 μg/ml. The EC50 for the ethanol extract of T. violacea against HT29 colon cancer cells was 101 μg/ml. The aqueous extracts of B. frutescens and T. camphoratus (0.5 and 50 μg/ml) produced the highest overall glucose uptake activity in Chang liver and C2C12 muscle cells. T. camphoratus was unanimously chosen by participating practitioners as the plant to be investigated further. The aqueous extract of T. camphoratus increased glucose uptake in C2C12 muscle cells through increased translocation of GLUT4 to the plasma membrane and activation of the PI3-kinase and AMP-kinase pathways. It produced some alpha-glucosidase inhibitory activity at concentrations of ≥ 200 μg/ml. Apart from interactive feedback seminars at which the findings were presented to participating practitioners, all scientific literature regarding the plants was summarised, translated, compiled and given to participating practitioners in written format. An indigenous knowledge agreement has been negotiated and will formalise the collaboration in future. It is recommended that future research focuses on plants with economic development potential that can be cultivated in the medicinal garden.
- Full Text:
- Date Issued: 2007
- Authors: Van Huyssteen, Mea
- Date: 2007
- Subjects: Medicinal plants -- South Africa -- Port Elizabeth , Healers -- South Africa -- Port Elizabeth , Anti-infective agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10148 , http://hdl.handle.net/10948/663 , Medicinal plants -- South Africa -- Port Elizabeth , Healers -- South Africa -- Port Elizabeth , Anti-infective agents
- Description: The promotion and development of indigenous knowledge pertaining to the traditional African healing system is one of the prime objectives set out by the South African government. Despite excellent research opportunities and funding, the biggest problem with ethnopharmacological research is a lack of interaction with indigenous communities, which tends to dilute the benefits this research has to offer these communities. The primary aim of this study was thus to promote the traditional African healing system through collaborative medicinal plant research with local traditional health practitioners. The research collaboration aimed to validate some biological activities of traditional remedies used by collaborating traditional health practitioners and ensured interactive sessions where scientific literature, research practices, findings and relevant legislation were discussed and debated. The joint development of a medicinal garden was a valuable tool in realising these goals. Aqueous and ethanol extracts of Bulbine frutescens, Ornithogalum longibracteatum, Ruta graveolens, Tarchonanthus camphoratus and Tulbaghia violacea were selected for antimicrobial, anticancer and anti-diabetic screening, because of their sustainable utilisation potential. The ethanol extract of T. violacea produced the best antimicrobial activity on Bacillus subtilis (100% growth inhibition) and Candida albicans (89% growth inhibition) at 250 μg/ml. The EC50 for the ethanol extract of T. violacea against HT29 colon cancer cells was 101 μg/ml. The aqueous extracts of B. frutescens and T. camphoratus (0.5 and 50 μg/ml) produced the highest overall glucose uptake activity in Chang liver and C2C12 muscle cells. T. camphoratus was unanimously chosen by participating practitioners as the plant to be investigated further. The aqueous extract of T. camphoratus increased glucose uptake in C2C12 muscle cells through increased translocation of GLUT4 to the plasma membrane and activation of the PI3-kinase and AMP-kinase pathways. It produced some alpha-glucosidase inhibitory activity at concentrations of ≥ 200 μg/ml. Apart from interactive feedback seminars at which the findings were presented to participating practitioners, all scientific literature regarding the plants was summarised, translated, compiled and given to participating practitioners in written format. An indigenous knowledge agreement has been negotiated and will formalise the collaboration in future. It is recommended that future research focuses on plants with economic development potential that can be cultivated in the medicinal garden.
- Full Text:
- Date Issued: 2007
Biological generation of reactive alkaline species and their application in a sustainable bioprocess for the remediation of acid and metal contaminated wastewaters
- Authors: Van Hille, Robert Paul
- Date: 2002
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21049 , http://hdl.handle.net/10962/6129
- Description: This project focused on the development of an integrated biological system for the treatment of acidic and metal-laden effluents, based on the sustainable biological generation of reactive alkaline species. Initial studies concentrated on the binding and accumulation of heavy metals by biomass of the cyanobacteria, Spirulina sp. Metal binding was rapid, with saturation reached in 30 minutes, and followed an affinity series of Pb > Cu > Zn >>Fe. The binding capacity of the Spirulina for each of the metals was relatively low when compared to a range of other biosorbents. The toxicity thresholds of the algae was determined for copper and zinc. These were low (10umoles/g) and as such, the algae were not suitable for application in a treatment system in which they came into direct contact with the toxic metals. The algae were able to increase the pH of the surrounding medium. This occurred as a result of the accumulation of inorganic carbon, from bicarbonate, as a response to low concentrations of carbon dioxide in the medium. The resulting release of a hydroxide ion into solution led to the increase in pH. The increase in pH was shown to be due to a reduction in acidity, rather than an increase in alkalinity. The enzyme carbonic anhydrase was shown to be pivotal in this system. Attempts to determine the enzyme activity directly were unsuccessful, due to the inherent inaccuracy of the assay system. An indirect method of determining enzyme activity, by measuring changes in the carbonate species equilibrium, was developed. Under optimal conditions Spirulina was able to reduce the acidity by an amount equivalent to the addition of 3670umoles NaOH g·' h·'. Predictive modelling showed that this enhanced the potential of the medium to effect metal precipitation. For the algal system to be sustainable, a readily available source of bicarbonate was needed. This was achieved by the oxidation of organic carbon, under sulphidogenic conditions, by a bacterial consortium isolated from the anaerobic component of a facultative pond. The consortium was shown to consist of sulphate reducing (most likely Desulvovibrio and Desulfotomaculum)and acetogenic bacteria. Sulphate removal rates of 500mg 1·' day·' and 135mg 1·' day·' were achieved in a 21 agitated and 281 upflow reactor respectively. The bicarbonate generation rate in the 281 reactor was calculated as 4033umoles 1·' day·', which proved sufficient to act as a feed for the algal system. Sparging the anaerobic digester overflow with air and nitrogen resulted in a reduction in the aqueous sulphide concentration. Using nitrogen, a 70% recovery of sulphide, as H2S gas, was achieved in 60 minutes, while with air, this dropped to 40%, due to the oxidation of the aqueous sulphide. The stripping ofH2S resulted in an increase in pH. The H2S gas was used for the selective precipitation of copper and lead in the integrated system. The dynamics of metal precipitation was investigated. For simple reactions, between individual IV metal and base species, it was possible to generate an accurate predictive model and confirm the precipitating species using wavelength dispersive X-ray spectroscopy (WDS). In more complex systems, where precipitation of the artificial acid mine drainage was examined, the predictive modelling and WDS could not accurately describe the system. The addition of aqueous sulphide to copper and iron resulted in the formation of metastable, amorphous precipitates, which remained in suspension. Ageing of the copper precipitate resulted in the evolution of a stable crystalline structure (covellite) and the aggregation and settling of the precipitate. In the case of iron, the amorphous precipitate underwent oxidation before a stable iron sulphide could evolve and the settled precipitate was an iron oxide or oxyhydroxide. The artificial acid mine drainage was treated with sulphide, hydroxide, anaerobic digester overflow and algal overflow. The best metal removal was achieved with the sulphide and hydroxide, while the algal overflow outperformed the anaerobic digester overflow. The precipitate generated by the addition of sulphide was the most compact, followed by the algal overflow, the anaerobic digester overflow and the hydroxide. Efficient precipitation of all the heavy metals, except manganese, was achieved using the algal overflow at an acidity to alkalinity ratio of 1 :2. This ratio was selected for use in the pilot system. The Spirulina based pilot system was effectively used to treat an effluent from the Black Mountain base metal mine. The necessity to maintain the algae in suspension and avoid biomass washout were practical considerations which counted against this system. The replacement of the Spirulina by Oscillatoria, which adhered to a solid support, overcame these problems. The integrated biological system was able to effectively treat an artificial acid mine drainage for 90 days, reducing the concentration of all metals, except manganese, to below the acceptable environmental risk levels. The treatment of the final effluent in a second anaerobic digester reduced the manganese concentration to 4.5uM and proved that the sulphate reducing bacteria could be cultivated on enriched, partially treated acid mine drainage. The integrated biological treatment system performed well, effectively treating an effluent modelled closely on the quality of the water being discharged from the East Rand Basin. The cost of such a system would be considerably less than a "high tech" physico-chemical system. This, coupled with the potential long term sustainability of a biological system, would make it a potentially attractive option for the treatment of future acid mine drainage discharges.
- Full Text:
- Date Issued: 2002
- Authors: Van Hille, Robert Paul
- Date: 2002
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21049 , http://hdl.handle.net/10962/6129
- Description: This project focused on the development of an integrated biological system for the treatment of acidic and metal-laden effluents, based on the sustainable biological generation of reactive alkaline species. Initial studies concentrated on the binding and accumulation of heavy metals by biomass of the cyanobacteria, Spirulina sp. Metal binding was rapid, with saturation reached in 30 minutes, and followed an affinity series of Pb > Cu > Zn >>Fe. The binding capacity of the Spirulina for each of the metals was relatively low when compared to a range of other biosorbents. The toxicity thresholds of the algae was determined for copper and zinc. These were low (10umoles/g) and as such, the algae were not suitable for application in a treatment system in which they came into direct contact with the toxic metals. The algae were able to increase the pH of the surrounding medium. This occurred as a result of the accumulation of inorganic carbon, from bicarbonate, as a response to low concentrations of carbon dioxide in the medium. The resulting release of a hydroxide ion into solution led to the increase in pH. The increase in pH was shown to be due to a reduction in acidity, rather than an increase in alkalinity. The enzyme carbonic anhydrase was shown to be pivotal in this system. Attempts to determine the enzyme activity directly were unsuccessful, due to the inherent inaccuracy of the assay system. An indirect method of determining enzyme activity, by measuring changes in the carbonate species equilibrium, was developed. Under optimal conditions Spirulina was able to reduce the acidity by an amount equivalent to the addition of 3670umoles NaOH g·' h·'. Predictive modelling showed that this enhanced the potential of the medium to effect metal precipitation. For the algal system to be sustainable, a readily available source of bicarbonate was needed. This was achieved by the oxidation of organic carbon, under sulphidogenic conditions, by a bacterial consortium isolated from the anaerobic component of a facultative pond. The consortium was shown to consist of sulphate reducing (most likely Desulvovibrio and Desulfotomaculum)and acetogenic bacteria. Sulphate removal rates of 500mg 1·' day·' and 135mg 1·' day·' were achieved in a 21 agitated and 281 upflow reactor respectively. The bicarbonate generation rate in the 281 reactor was calculated as 4033umoles 1·' day·', which proved sufficient to act as a feed for the algal system. Sparging the anaerobic digester overflow with air and nitrogen resulted in a reduction in the aqueous sulphide concentration. Using nitrogen, a 70% recovery of sulphide, as H2S gas, was achieved in 60 minutes, while with air, this dropped to 40%, due to the oxidation of the aqueous sulphide. The stripping ofH2S resulted in an increase in pH. The H2S gas was used for the selective precipitation of copper and lead in the integrated system. The dynamics of metal precipitation was investigated. For simple reactions, between individual IV metal and base species, it was possible to generate an accurate predictive model and confirm the precipitating species using wavelength dispersive X-ray spectroscopy (WDS). In more complex systems, where precipitation of the artificial acid mine drainage was examined, the predictive modelling and WDS could not accurately describe the system. The addition of aqueous sulphide to copper and iron resulted in the formation of metastable, amorphous precipitates, which remained in suspension. Ageing of the copper precipitate resulted in the evolution of a stable crystalline structure (covellite) and the aggregation and settling of the precipitate. In the case of iron, the amorphous precipitate underwent oxidation before a stable iron sulphide could evolve and the settled precipitate was an iron oxide or oxyhydroxide. The artificial acid mine drainage was treated with sulphide, hydroxide, anaerobic digester overflow and algal overflow. The best metal removal was achieved with the sulphide and hydroxide, while the algal overflow outperformed the anaerobic digester overflow. The precipitate generated by the addition of sulphide was the most compact, followed by the algal overflow, the anaerobic digester overflow and the hydroxide. Efficient precipitation of all the heavy metals, except manganese, was achieved using the algal overflow at an acidity to alkalinity ratio of 1 :2. This ratio was selected for use in the pilot system. The Spirulina based pilot system was effectively used to treat an effluent from the Black Mountain base metal mine. The necessity to maintain the algae in suspension and avoid biomass washout were practical considerations which counted against this system. The replacement of the Spirulina by Oscillatoria, which adhered to a solid support, overcame these problems. The integrated biological system was able to effectively treat an artificial acid mine drainage for 90 days, reducing the concentration of all metals, except manganese, to below the acceptable environmental risk levels. The treatment of the final effluent in a second anaerobic digester reduced the manganese concentration to 4.5uM and proved that the sulphate reducing bacteria could be cultivated on enriched, partially treated acid mine drainage. The integrated biological treatment system performed well, effectively treating an effluent modelled closely on the quality of the water being discharged from the East Rand Basin. The cost of such a system would be considerably less than a "high tech" physico-chemical system. This, coupled with the potential long term sustainability of a biological system, would make it a potentially attractive option for the treatment of future acid mine drainage discharges.
- Full Text:
- Date Issued: 2002
A formalised ontology for network attack classification
- Authors: Van Heerden, Renier Pelser
- Date: 2014
- Subjects: Computer networks -- Security measures Computer security Computer crimes -- Investigation Computer crimes -- Prevention
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4691 , http://hdl.handle.net/10962/d1011603
- Description: One of the most popular attack vectors against computers are their network connections. Attacks on computers through their networks are commonplace and have various levels of complexity. This research formally describes network-based computer attacks in the form of a story, formally and within an ontology. The ontology categorises network attacks where attack scenarios are the focal class. This class consists of: Denial-of- Service, Industrial Espionage, Web Defacement, Unauthorised Data Access, Financial Theft, Industrial Sabotage, Cyber-Warfare, Resource Theft, System Compromise, and Runaway Malware. This ontology was developed by building a taxonomy and a temporal network attack model. Network attack instances (also know as individuals) are classified according to their respective attack scenarios, with the use of an automated reasoner within the ontology. The automated reasoner deductions are verified formally; and via the automated reasoner, a relaxed set of scenarios is determined, which is relevant in a near real-time environment. A prototype system (called Aeneas) was developed to classify network-based attacks. Aeneas integrates the sensors into a detection system that can classify network attacks in a near real-time environment. To verify the ontology and the prototype Aeneas, a virtual test bed was developed in which network-based attacks were generated to verify the detection system. Aeneas was able to detect incoming attacks and classify them according to their scenario. The novel part of this research is the attack scenarios that are described in the form of a story, as well as formally and in an ontology. The ontology is used in a novel way to determine to which class attack instances belong and how the network attack ontology is affected in a near real-time environment.
- Full Text:
- Date Issued: 2014
- Authors: Van Heerden, Renier Pelser
- Date: 2014
- Subjects: Computer networks -- Security measures Computer security Computer crimes -- Investigation Computer crimes -- Prevention
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4691 , http://hdl.handle.net/10962/d1011603
- Description: One of the most popular attack vectors against computers are their network connections. Attacks on computers through their networks are commonplace and have various levels of complexity. This research formally describes network-based computer attacks in the form of a story, formally and within an ontology. The ontology categorises network attacks where attack scenarios are the focal class. This class consists of: Denial-of- Service, Industrial Espionage, Web Defacement, Unauthorised Data Access, Financial Theft, Industrial Sabotage, Cyber-Warfare, Resource Theft, System Compromise, and Runaway Malware. This ontology was developed by building a taxonomy and a temporal network attack model. Network attack instances (also know as individuals) are classified according to their respective attack scenarios, with the use of an automated reasoner within the ontology. The automated reasoner deductions are verified formally; and via the automated reasoner, a relaxed set of scenarios is determined, which is relevant in a near real-time environment. A prototype system (called Aeneas) was developed to classify network-based attacks. Aeneas integrates the sensors into a detection system that can classify network attacks in a near real-time environment. To verify the ontology and the prototype Aeneas, a virtual test bed was developed in which network-based attacks were generated to verify the detection system. Aeneas was able to detect incoming attacks and classify them according to their scenario. The novel part of this research is the attack scenarios that are described in the form of a story, as well as formally and in an ontology. The ontology is used in a novel way to determine to which class attack instances belong and how the network attack ontology is affected in a near real-time environment.
- Full Text:
- Date Issued: 2014
A phenomenological investigation into undergraduate students' experience of acquiring the discourse of engineering
- Authors: Van Heerden, Karen Ilse
- Date: 2001
- Subjects: Education, Higher -- South Africa Students -- Attitudes Academic writing -- Study and teaching -- South Africa English language -- Rhetoric -- Study and teaching -- South Africa Technical writing -- Study and teaching
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1698 , http://hdl.handle.net/10962/d1003581
- Description: The area of discourse acquisition and writing in higher education has become a much researched field. In South Africa the interest in discourse acquisition and writing has been partly in response to the change in student profile, particularly over the past ten years. While South African researchers and academics are increasingly focusing their interest in discourse acquisition and writing on the unique circumstances here, they rely on theories based on research done in very different social contexts. These theories are not necessarily universally appropriate. South Africa is currently undergoing a period of transformation in higher education aimed at greater access and equity for black students and academics. The accompanying sense of frustration and disillusionment among students and academics underlines the need to reappraise all aspects of higher education. Much of the research on discourse acquisition and writing is undertaken in arts programmes: vocational fields - such as engineering education - tend to be neglected. If the envisaged growth in science and engineering education is to be realised, it is essential that research in discourse and writing be undertaken in engineering programmes. This study investigates discourse acquisition as experienced by students in a South African engineering faculty. The experiences of six final year technikon students are investigated to gain a better understanding of what it means to acquire the discourse of engineering. The phenomenological method used requires that the researcher suspends or brackets a priori theoretical notions or pre-conceptions so that that which the students experience, rather than what the researcher expects in terms of theory, can emerge. What emerges from the students' experiences is partially congruent with established discourse and writing theories. However, some of the student experiences of discourse acquisition differ in significant ways from what is described in mainstream writing and discourse acquisition theory. The differences in the manner in which these students experience their acquisition of engineering discourse leads to a new understanding of the phenomenon. The students do not experience the alienation or struggle described in mainstream theoretic accounts of discourse acquisition. Students' approaches to writing are affected by their awareness of their multiple identities and the different locations in which they learn. Their approaches to writing are significantly different in some respects from descriptions in mainstream theories in some respects. The description of their experiences gives a different understanding of what it means to acquire the discourse of engineering, and may contribute to the reappraisal of engineering education in a contemporary South African context.
- Full Text:
- Date Issued: 2001
- Authors: Van Heerden, Karen Ilse
- Date: 2001
- Subjects: Education, Higher -- South Africa Students -- Attitudes Academic writing -- Study and teaching -- South Africa English language -- Rhetoric -- Study and teaching -- South Africa Technical writing -- Study and teaching
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1698 , http://hdl.handle.net/10962/d1003581
- Description: The area of discourse acquisition and writing in higher education has become a much researched field. In South Africa the interest in discourse acquisition and writing has been partly in response to the change in student profile, particularly over the past ten years. While South African researchers and academics are increasingly focusing their interest in discourse acquisition and writing on the unique circumstances here, they rely on theories based on research done in very different social contexts. These theories are not necessarily universally appropriate. South Africa is currently undergoing a period of transformation in higher education aimed at greater access and equity for black students and academics. The accompanying sense of frustration and disillusionment among students and academics underlines the need to reappraise all aspects of higher education. Much of the research on discourse acquisition and writing is undertaken in arts programmes: vocational fields - such as engineering education - tend to be neglected. If the envisaged growth in science and engineering education is to be realised, it is essential that research in discourse and writing be undertaken in engineering programmes. This study investigates discourse acquisition as experienced by students in a South African engineering faculty. The experiences of six final year technikon students are investigated to gain a better understanding of what it means to acquire the discourse of engineering. The phenomenological method used requires that the researcher suspends or brackets a priori theoretical notions or pre-conceptions so that that which the students experience, rather than what the researcher expects in terms of theory, can emerge. What emerges from the students' experiences is partially congruent with established discourse and writing theories. However, some of the student experiences of discourse acquisition differ in significant ways from what is described in mainstream writing and discourse acquisition theory. The differences in the manner in which these students experience their acquisition of engineering discourse leads to a new understanding of the phenomenon. The students do not experience the alienation or struggle described in mainstream theoretic accounts of discourse acquisition. Students' approaches to writing are affected by their awareness of their multiple identities and the different locations in which they learn. Their approaches to writing are significantly different in some respects from descriptions in mainstream theories in some respects. The description of their experiences gives a different understanding of what it means to acquire the discourse of engineering, and may contribute to the reappraisal of engineering education in a contemporary South African context.
- Full Text:
- Date Issued: 2001
Postmodernistiese vertelstrategieë in Nag van die clown van Abraham H. de Vries
- Authors: Van Heerden, Etienne, 1954-
- Date: 1996
- Subjects: De Vries, Abraham H. -- Criticism and interpretation De Vries, Abraham H. -- Nag van die clown Afrikaans fiction -- History and criticism Postmodernism (Literature) Postmodernism (Literature) -- South Africa
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3595 , http://hdl.handle.net/10962/d1002170
- Description: This thesis locates Abraham H. de Vries's Nag van ale Clown witbin the self-conscious South African socio-literary climate of the eighties and analyses postmodernist narrative strategies in five stories. Surveying the debate on postmodernism, this study describes postmodernism as a nomadic, inherently contradictory and mutually informing palimpsest of texts and views the De Vries text as a problematized inscribing of subjectivity into history. , Hierdie proefskrif situeer Nag van die Clown (1989) van Abraham H. de Vries binne die selfbewuste sosioliterere klimaat van die Suid-Afrika van die dekade tagtig en ontleed postmodernistiese vertelstrategiee in vyf verhale uit die bundel. Die studie bied 'n oorsig oor die debat rondom die postmodernisme as nomadiese, weersprekende en wedersyds voedende palimpses tekste en beskou die De Vries-teks as 'n problematiserende inskryf van subjektiwiteit in die geskiedenis.
- Full Text:
- Date Issued: 1996
- Authors: Van Heerden, Etienne, 1954-
- Date: 1996
- Subjects: De Vries, Abraham H. -- Criticism and interpretation De Vries, Abraham H. -- Nag van die clown Afrikaans fiction -- History and criticism Postmodernism (Literature) Postmodernism (Literature) -- South Africa
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3595 , http://hdl.handle.net/10962/d1002170
- Description: This thesis locates Abraham H. de Vries's Nag van ale Clown witbin the self-conscious South African socio-literary climate of the eighties and analyses postmodernist narrative strategies in five stories. Surveying the debate on postmodernism, this study describes postmodernism as a nomadic, inherently contradictory and mutually informing palimpsest of texts and views the De Vries text as a problematized inscribing of subjectivity into history. , Hierdie proefskrif situeer Nag van die Clown (1989) van Abraham H. de Vries binne die selfbewuste sosioliterere klimaat van die Suid-Afrika van die dekade tagtig en ontleed postmodernistiese vertelstrategiee in vyf verhale uit die bundel. Die studie bied 'n oorsig oor die debat rondom die postmodernisme as nomadiese, weersprekende en wedersyds voedende palimpses tekste en beskou die De Vries-teks as 'n problematiserende inskryf van subjektiwiteit in die geskiedenis.
- Full Text:
- Date Issued: 1996
Individual-related factors influencing knowledge-sharing intention in knowledge-intensive businesses
- Authors: Van Greunen, Conrad
- Date: 2017
- Subjects: Knowledge management Intellectual capital -- Management , Management -- Information services Organizational learning
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/21274 , vital:29469
- Description: It has become generally accepted to refer to today‟s global economy as a knowledge-based economy, since knowledge has increasingly become the resource, instead of a resource for wealth creation. The ability of businesses to harness the potential of intangible assets such as knowledge has become far more decisive than their ability to manage physical assets. In the implementation of knowledge management activities, knowledge sharing is recognised as an integral task and key enabler of knowledge management. Although knowledge sharing is regarded as one of the most crucial factors in the effective management of knowledge, in knowledge-intensive businesses in particular, it has also been established that most employees are reluctant to share knowledge. Research further confirms that the factors that promote or discourage knowledge-sharing behaviour in businesses are poorly understood and that knowledge management systems fail as a result of the misunderstanding of individual characteristics that could influence knowledge sharing. Moreover, the focus of knowledge-sharing literature, in terms of the unit of analysis, is rarely at an individual/micro level, although the role of individuals in the knowledge-sharing process is critical as tacit knowledge resides within the individual and knowledge sharing starts with individuals. Given the importance of understanding knowledge sharing of individuals in knowledge-intensive businesses – but noting the lack of existing systematic, integrated research that focuses on individual-related factors influencing knowledge sharing – the purpose of this study was to fill the gap in the current literature. As such, the primary objective of this research was to identify and empirically investigate the individual-related factors influencing the Knowledge-sharing intention of individual employees in knowledge-intensive businesses. The literature review revealed twelve constructs, namely Individuals’ awareness, Intrinsic motivation, Extrinsic motivation, Transactional psychological contract breach, Relational psychological contract breach, Relationship conflict, Task conflict, Extraversion, Neuroticism, Openness to experience, Agreeableness and Conscientiousness that could influence the dependent variable Knowledge-sharing intention in knowledge-intensive businesses. Various moderating relationships between the dependent and independent variables were also proposed, while seven demographic variables (Age, Gender, Language, Highest qualification, Ethnic background, Organisational tenure and Job tenure of the respondent) were identified as potential control variables. Each construct in the hypothesised model of individual-related factors influencing Knowledge-sharing intention was defined and operationalised using items sourced from validated measuring instruments in previous studies. Several self-generated items based on secondary sources were also formulated. A structured questionnaire was made available to respondents identified by means of the convenience sampling technique, and the data collected from 597 usable questionnaires was subjected to various statistical analyses. An exploratory factor analysis (EFA) was conducted which confirmed the unique factors present in the data, and Cronbach-alpha coefficients were calculated to confirm the reliability of the measuring instrument. Structural equation modelling (SEM) was the main statistical procedure used to test the significance of the relationships hypothesised between the various independent and dependent variables. A subset of SEM, namely general linear modelling (GLM) was used to determine the influence of selected demographic variables on Knowledge-sharing intention and to assess various moderating relationships as proposed in the hypothesised model. The main findings of this study were that personality traits are strong predictors of individual employees‟ willingness to share knowledge, and that the maturity of individuals, in terms of realising the significance and value of sharing their knowledge with others, and in recognising the intrinsic benefits of sharing, influence Knowledge-sharing intention. The main limitations of the study were the use of a convenience sampling technique to collect the data, as well as the dependence of self-report by respondents, which could lead to response bias. This study has added to the body of knowledge management research, in particular knowledge-sharing research, by investigating selected individual-related factors influencing the Knowledge-sharing intention of individuals in a particular subset of businesses, namely knowledge-intensive businesses, and focusing on a particular type of knowledge, namely tacit knowledge. From a business‟s perspective, this study offers recommendations and suggestions for managing these individual-related factors in such a way as to increase knowledge sharing among employees, and as a result, the effectiveness and competitive advantage of knowledge-intensive businesses.
- Full Text:
- Date Issued: 2017
Individual-related factors influencing knowledge-sharing intention in knowledge-intensive businesses
- Authors: Van Greunen, Conrad
- Date: 2017
- Subjects: Knowledge management Intellectual capital -- Management , Management -- Information services Organizational learning
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/21274 , vital:29469
- Description: It has become generally accepted to refer to today‟s global economy as a knowledge-based economy, since knowledge has increasingly become the resource, instead of a resource for wealth creation. The ability of businesses to harness the potential of intangible assets such as knowledge has become far more decisive than their ability to manage physical assets. In the implementation of knowledge management activities, knowledge sharing is recognised as an integral task and key enabler of knowledge management. Although knowledge sharing is regarded as one of the most crucial factors in the effective management of knowledge, in knowledge-intensive businesses in particular, it has also been established that most employees are reluctant to share knowledge. Research further confirms that the factors that promote or discourage knowledge-sharing behaviour in businesses are poorly understood and that knowledge management systems fail as a result of the misunderstanding of individual characteristics that could influence knowledge sharing. Moreover, the focus of knowledge-sharing literature, in terms of the unit of analysis, is rarely at an individual/micro level, although the role of individuals in the knowledge-sharing process is critical as tacit knowledge resides within the individual and knowledge sharing starts with individuals. Given the importance of understanding knowledge sharing of individuals in knowledge-intensive businesses – but noting the lack of existing systematic, integrated research that focuses on individual-related factors influencing knowledge sharing – the purpose of this study was to fill the gap in the current literature. As such, the primary objective of this research was to identify and empirically investigate the individual-related factors influencing the Knowledge-sharing intention of individual employees in knowledge-intensive businesses. The literature review revealed twelve constructs, namely Individuals’ awareness, Intrinsic motivation, Extrinsic motivation, Transactional psychological contract breach, Relational psychological contract breach, Relationship conflict, Task conflict, Extraversion, Neuroticism, Openness to experience, Agreeableness and Conscientiousness that could influence the dependent variable Knowledge-sharing intention in knowledge-intensive businesses. Various moderating relationships between the dependent and independent variables were also proposed, while seven demographic variables (Age, Gender, Language, Highest qualification, Ethnic background, Organisational tenure and Job tenure of the respondent) were identified as potential control variables. Each construct in the hypothesised model of individual-related factors influencing Knowledge-sharing intention was defined and operationalised using items sourced from validated measuring instruments in previous studies. Several self-generated items based on secondary sources were also formulated. A structured questionnaire was made available to respondents identified by means of the convenience sampling technique, and the data collected from 597 usable questionnaires was subjected to various statistical analyses. An exploratory factor analysis (EFA) was conducted which confirmed the unique factors present in the data, and Cronbach-alpha coefficients were calculated to confirm the reliability of the measuring instrument. Structural equation modelling (SEM) was the main statistical procedure used to test the significance of the relationships hypothesised between the various independent and dependent variables. A subset of SEM, namely general linear modelling (GLM) was used to determine the influence of selected demographic variables on Knowledge-sharing intention and to assess various moderating relationships as proposed in the hypothesised model. The main findings of this study were that personality traits are strong predictors of individual employees‟ willingness to share knowledge, and that the maturity of individuals, in terms of realising the significance and value of sharing their knowledge with others, and in recognising the intrinsic benefits of sharing, influence Knowledge-sharing intention. The main limitations of the study were the use of a convenience sampling technique to collect the data, as well as the dependence of self-report by respondents, which could lead to response bias. This study has added to the body of knowledge management research, in particular knowledge-sharing research, by investigating selected individual-related factors influencing the Knowledge-sharing intention of individuals in a particular subset of businesses, namely knowledge-intensive businesses, and focusing on a particular type of knowledge, namely tacit knowledge. From a business‟s perspective, this study offers recommendations and suggestions for managing these individual-related factors in such a way as to increase knowledge sharing among employees, and as a result, the effectiveness and competitive advantage of knowledge-intensive businesses.
- Full Text:
- Date Issued: 2017
Characterisation of the cellulolytic and hemicellulolytic system of Bacillus Licheniformis SVD1 and the isolation and characterisation of a multi-enzyme complex
- Authors: Van Dyk, Jacoba Susanna
- Date: 2009
- Subjects: Lignocellulose Lignocellulose -- Biotechnology Lignocellulose -- Biodegradation Plant biotechnology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3936 , http://hdl.handle.net/10962/d1003995
- Description: The biological degradation of lignocellulose into fermentable sugars for the production of liquid transportation fuels is feasible and sustainable, but equires a variety of enzymes working in synergy as lignocellulose is a complex and recalcitrant substrate. The cellulosome is a multi-enzyme complex (MEC) with a variety of cellulolytic and hemicellulolytic enzymes that appears to facilitate an enhanced synergy and efficiency, as compared to free enzymes, for the degradation of recalcitrant substrates such as lignocellulose and plant cell walls. Most of the studies on cellulosomes have focused on a few organisms; C. thermocellum, C. cellulovorans and C. cellulolyticum, and there is only limited knowledge vailable on similar complexes in other organisms. Some MECs have been identified in aerobic bacteria such as Bacillus circulans and Paenibacillus curdlanolyticus, but the nature of these MECs have not been fully elucidated. This study investigated the cellulolytic and emi-cellulolytic system of Bacillus licheniformis SVD1 with specific reference to the presence of a MEC, which has never been reported in the literature for B. licheniformis. A MEC of approximately 2,000 kDa in size, based on size exclusion chromatography using Sepharose 4B, was purified from a culture of B. licheniformis. When investigating the presence of enzyme activity in the total crude fraction as well as the MEC of a birchwood xylan culture, B. licheniformis was found to display a variety of enzyme activities on a range of substrates, although xylanases were by far the predominant enzyme activity present in both the crude and MEC fractions. Based on zymogram analysis there were three CMCases, seven xylanases, three mannanases and two pectinases in the crude fraction, while the MEC had two CMCases, seven xylanases, two mannanases and one pectinase. The pectinases in the crude could be identified as a pectin methyl esterase and a lyase, while the methyl esterase was absent in the MEC. Seventeen protein species could be detected in the MEC but only nine of these displayed activity on the substrates tested. The possible presence of a β-xylosidase in the crude fraction was deduced from thin layer chromatography (TLC) which demonstrated the production of xylose by the crude fraction. It was furthermore established that B. licheniformis SVD1 was able to regulate levels of enzyme expression based on the substrate the organism was cultured on. It was found that complexed xylanase activity had a pH optimum of between pH 6.0 and 7.0 and a temperature optimum of 55oC. Complexed xylanase activity was found to be slightly inhibited by CaCl2 and inhibited to a greater extent by EDTA. Complexed xylanase activity was further shown to be activated in the presence of xylose and xylobiose, both compounds which are products of enzymatic degradation. Ethanol was found to inhibit complexed xylanase activity. The kinetic parameters for complexed xylanase activity were measured and the Km value was calculated as 2.84 mg/ml while the maximal velocity (Vmax) was calculated as 0.146 U (μmol/min/ml). Binding studies, transmission electron microscopy (TEM) and a bioinformatic analysis was conducted to investigate whether the MEC in B. licheniformis SVD1 was a putative cellulosome. The MEC was found to be unable to bind to Avicel, but was able to bind to insoluble birchwood xylan, indicating the absence of a CBM3a domain common to cellulosomal scaffoldin proteins. TEM micrographs revealed the presence of cell surface structures on cells of B. licheniformis SVD1 cultured on cellobiose and birchwood xylan. However, it could not be established whether these cell surface structures could be ascribed to the presence of the MECs on the cell surface. Bioinformatic analysis was conducted on the available genome sequence of a different strain of B. licheniformis, namely DSM 13 and ATCC 14580. No sequence homology was found with cohesin and dockerin sequences from various cellulosomal species, indicating that these strains most likely do not encode for a cellulosome. This study described and characterised a MEC that was a functional enzyme complex and did not appear to be a mere aggregation of proteins. It displayed a variety of hemi-cellulolytic activities and the available evidence suggests that it is not a cellulosome, but should rather be termed a xylanosome. Further investigation should be carried out to determine the structural basis of this MEC.
- Full Text:
- Date Issued: 2009
- Authors: Van Dyk, Jacoba Susanna
- Date: 2009
- Subjects: Lignocellulose Lignocellulose -- Biotechnology Lignocellulose -- Biodegradation Plant biotechnology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3936 , http://hdl.handle.net/10962/d1003995
- Description: The biological degradation of lignocellulose into fermentable sugars for the production of liquid transportation fuels is feasible and sustainable, but equires a variety of enzymes working in synergy as lignocellulose is a complex and recalcitrant substrate. The cellulosome is a multi-enzyme complex (MEC) with a variety of cellulolytic and hemicellulolytic enzymes that appears to facilitate an enhanced synergy and efficiency, as compared to free enzymes, for the degradation of recalcitrant substrates such as lignocellulose and plant cell walls. Most of the studies on cellulosomes have focused on a few organisms; C. thermocellum, C. cellulovorans and C. cellulolyticum, and there is only limited knowledge vailable on similar complexes in other organisms. Some MECs have been identified in aerobic bacteria such as Bacillus circulans and Paenibacillus curdlanolyticus, but the nature of these MECs have not been fully elucidated. This study investigated the cellulolytic and emi-cellulolytic system of Bacillus licheniformis SVD1 with specific reference to the presence of a MEC, which has never been reported in the literature for B. licheniformis. A MEC of approximately 2,000 kDa in size, based on size exclusion chromatography using Sepharose 4B, was purified from a culture of B. licheniformis. When investigating the presence of enzyme activity in the total crude fraction as well as the MEC of a birchwood xylan culture, B. licheniformis was found to display a variety of enzyme activities on a range of substrates, although xylanases were by far the predominant enzyme activity present in both the crude and MEC fractions. Based on zymogram analysis there were three CMCases, seven xylanases, three mannanases and two pectinases in the crude fraction, while the MEC had two CMCases, seven xylanases, two mannanases and one pectinase. The pectinases in the crude could be identified as a pectin methyl esterase and a lyase, while the methyl esterase was absent in the MEC. Seventeen protein species could be detected in the MEC but only nine of these displayed activity on the substrates tested. The possible presence of a β-xylosidase in the crude fraction was deduced from thin layer chromatography (TLC) which demonstrated the production of xylose by the crude fraction. It was furthermore established that B. licheniformis SVD1 was able to regulate levels of enzyme expression based on the substrate the organism was cultured on. It was found that complexed xylanase activity had a pH optimum of between pH 6.0 and 7.0 and a temperature optimum of 55oC. Complexed xylanase activity was found to be slightly inhibited by CaCl2 and inhibited to a greater extent by EDTA. Complexed xylanase activity was further shown to be activated in the presence of xylose and xylobiose, both compounds which are products of enzymatic degradation. Ethanol was found to inhibit complexed xylanase activity. The kinetic parameters for complexed xylanase activity were measured and the Km value was calculated as 2.84 mg/ml while the maximal velocity (Vmax) was calculated as 0.146 U (μmol/min/ml). Binding studies, transmission electron microscopy (TEM) and a bioinformatic analysis was conducted to investigate whether the MEC in B. licheniformis SVD1 was a putative cellulosome. The MEC was found to be unable to bind to Avicel, but was able to bind to insoluble birchwood xylan, indicating the absence of a CBM3a domain common to cellulosomal scaffoldin proteins. TEM micrographs revealed the presence of cell surface structures on cells of B. licheniformis SVD1 cultured on cellobiose and birchwood xylan. However, it could not be established whether these cell surface structures could be ascribed to the presence of the MECs on the cell surface. Bioinformatic analysis was conducted on the available genome sequence of a different strain of B. licheniformis, namely DSM 13 and ATCC 14580. No sequence homology was found with cohesin and dockerin sequences from various cellulosomal species, indicating that these strains most likely do not encode for a cellulosome. This study described and characterised a MEC that was a functional enzyme complex and did not appear to be a mere aggregation of proteins. It displayed a variety of hemi-cellulolytic activities and the available evidence suggests that it is not a cellulosome, but should rather be termed a xylanosome. Further investigation should be carried out to determine the structural basis of this MEC.
- Full Text:
- Date Issued: 2009
Numerical relativity on cosmological past null cones
- Van der Walt, Petrus Johannes
- Authors: Van der Walt, Petrus Johannes
- Date: 2013
- Subjects: Cosmology Numerical calculations General relativity (Physics) -- Mathematics Einstein field equations Gravity Gravitational waves Horizon
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5396 , http://hdl.handle.net/10962/d1002959
- Description: The observational approach to cosmology is the endeavour to reconstruct the geometry of the Universe using only data that is theoretically verifiable within the causal boundaries of a cosmological observer. Using this approach, it was shown in [36] that given ideal cosmological observations, the only essential assumption necessary to determine the geometry of the Universe is a theory of gravity. Assuming General Relativity, the full set of Einstein field equations (EFEs) can be used to reconstruct the geometry of the Universe using direct observations on the past null cone (PNC) as initial conditions. Observationally and theoretically this is a very ambitious task and therefore, current developments have been restricted to spherically symmetric dust models while only relaxing the usual assumption of homogeneity in the radial direction. These restricted models are important for the development of theoretical foundations and also useful as verification models since they avoid the circularity of verifying what has already been assumed. The work presented in this thesis is the development of such a model where numerical relativity (NR) is used to simulate the observable universe. Similar to the work of Ellis and co-workers [36], a reference frame based on the PNC is used. The reference frame used here, however, is based on that of the characteristic formalism of NR, which has developed for calculating the propagation of gravitational waves. This provides a formalism that is well established in NR, making the use of existing algorithms possible. The Bondi-Sachs coordinates of the characteristic formalism is, however, not suitable for calculations beyond the observer apparent horizon (AH) since the diameter distance used as a radial coordinate becomes multi-valued when the cosmological PNC reconverges in the history of a universe, smaller in the past. With this taken into consideration, the Bondi-Sachs characteristic formalism is implemented for cosmology and the problem approaching the AH is investigated. Further developments address the limitations approaching the AH by introducing a metric based on the Bondi-Sachs metric where the radial coordinate is replaced with an affine parameter. The model is derived with a cosmological constant Λ incorporated into the EFEs where Λ is taken as a parameter of the theory of gravity rather than as a matter source term. Similar to the conventional characteristic formalism, this model consists of a system of differential equations for numerically evolving the EFEs as a characteristic initial value problem (CIVP). A numerical code implemented for the method has been found to be second order convergent. This code enables simulations of different models given identical data on the initial null cone and provides a method to investigate their physical consistency within the causally connected region of our current PNC. These developments closely follow existing 3D schemes developed for gravitational wave simulations, which should make it natural to extend the affine CIVP beyond spherical symmetric simulations. The developments presented in this thesis is an extended version of two papers published earlier.
- Full Text:
- Date Issued: 2013
- Authors: Van der Walt, Petrus Johannes
- Date: 2013
- Subjects: Cosmology Numerical calculations General relativity (Physics) -- Mathematics Einstein field equations Gravity Gravitational waves Horizon
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5396 , http://hdl.handle.net/10962/d1002959
- Description: The observational approach to cosmology is the endeavour to reconstruct the geometry of the Universe using only data that is theoretically verifiable within the causal boundaries of a cosmological observer. Using this approach, it was shown in [36] that given ideal cosmological observations, the only essential assumption necessary to determine the geometry of the Universe is a theory of gravity. Assuming General Relativity, the full set of Einstein field equations (EFEs) can be used to reconstruct the geometry of the Universe using direct observations on the past null cone (PNC) as initial conditions. Observationally and theoretically this is a very ambitious task and therefore, current developments have been restricted to spherically symmetric dust models while only relaxing the usual assumption of homogeneity in the radial direction. These restricted models are important for the development of theoretical foundations and also useful as verification models since they avoid the circularity of verifying what has already been assumed. The work presented in this thesis is the development of such a model where numerical relativity (NR) is used to simulate the observable universe. Similar to the work of Ellis and co-workers [36], a reference frame based on the PNC is used. The reference frame used here, however, is based on that of the characteristic formalism of NR, which has developed for calculating the propagation of gravitational waves. This provides a formalism that is well established in NR, making the use of existing algorithms possible. The Bondi-Sachs coordinates of the characteristic formalism is, however, not suitable for calculations beyond the observer apparent horizon (AH) since the diameter distance used as a radial coordinate becomes multi-valued when the cosmological PNC reconverges in the history of a universe, smaller in the past. With this taken into consideration, the Bondi-Sachs characteristic formalism is implemented for cosmology and the problem approaching the AH is investigated. Further developments address the limitations approaching the AH by introducing a metric based on the Bondi-Sachs metric where the radial coordinate is replaced with an affine parameter. The model is derived with a cosmological constant Λ incorporated into the EFEs where Λ is taken as a parameter of the theory of gravity rather than as a matter source term. Similar to the conventional characteristic formalism, this model consists of a system of differential equations for numerically evolving the EFEs as a characteristic initial value problem (CIVP). A numerical code implemented for the method has been found to be second order convergent. This code enables simulations of different models given identical data on the initial null cone and provides a method to investigate their physical consistency within the causally connected region of our current PNC. These developments closely follow existing 3D schemes developed for gravitational wave simulations, which should make it natural to extend the affine CIVP beyond spherical symmetric simulations. The developments presented in this thesis is an extended version of two papers published earlier.
- Full Text:
- Date Issued: 2013
Thermal tolerance and the potential effects of climate change on coastal intertidal and estuarine organisms in the Kariega Estuary and adjacent intertitdal coastline, Eastern Cape, South Africa
- Authors: Van der Walt, Kerry-Ann
- Date: 2020
- Subjects: Ectotherms -- Climatic factors , Ectotherms -- Effect of temperature on , Fishes -- Climatic factors , Fishes -- Effect of temperature on , Climatic changes -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/148459 , vital:38741
- Description: Temperature changes due to the effects of climate change are evident on all continents and oceans. As a result, there is a growing concern over how marine ectotherms will respond to extreme or fluctuating environmental temperatures. Temperature changes have strong direct and indirect effects on individual, population, and ecosystem functioning traits. A multi-scale approach determining the thermal tolerance and performance of several marine ectotherms belonging to different coastal habitats is rarely considered in thermal physiology studies but is effective for an integrated ecosystem assessment. As such, for this thesis, I aimed to quantify and compare the thermal tolerance and performance of a range of coastal marine ectotherms (fish and macro-invertebrates) with different biogeographical distributions from estuarine, subtidal and rocky intertidal habitats to available and projected in situ temperature data. This was also undertaken to gauge the local vulnerability of each species across summer and winter in a warm-temperate region of South Africa. This was done using a multi-method physiological approach, which included the dynamic method (CTmax and CTmin), static respirometry and maximum heart rate fHmax). Results of the dynamic method on several fish and macro-invertebrate species indicated that there are differences in thermal tolerance according to taxonomy, biogeography and habitat for both summer and winter. Macro-invertebrate species generally had higher CTmax endpoints, lower CTmin endpoints, higher upper and lower breadths in tolerance, higher upper and lower thermal safety margins and higher thermal scopes than the fish species. This could be a result of the macro-invertebrate species studied being less mobile compared with fish species (which are able to move to more favourable conditions) as well as having broader geographical distributions. In addition, macro-invertebrates from the intertidal rock pool habitat (Palaemon peringueyi; Pernaperna) were more tolerant of high and low temperatures compared with the macro-invertebrates from the estuarine habitat (Clibanarius virescens; Parasesarma catenatum; Upogebia africana). Overall, macro-invertebrates, with the exception of Parechinus angulosus, investigated in this study indicated that current temperatures and projected climate change scenarios across seasons would not have a significant impact on them and that they are highly adaptable to changing temperature regimes. This sign of high tolerance was further supported by the heart rates of P. perna and P. catenatum under an acute increase in temperature (1.0 °C.h-1) which showed individuals of each species physiologically depressing their metabolism until a final Arrhenius breakpoint temperature was reached (TAB). Among the fish species investigated in this study, tropical species (Chaetodon marleyi; Kuhlia mugil) had the highest CTmax and CTmin endpoints when compared with the temperate (Diplodus capensis; Sarpa salpa), warm-water endemic (Chelon dumerili; Rhabdosargus holubi) and cool-water endemic (Chelon richardsonii) fishes. This suggests that due to their lower breadths in tolerance and thermal safety margins being small, tropical species may be less tolerant of cold temperatures and thermal variability, especially in the form of summer upwelling events which are expected to increase in intensity and frequency in this region as a result of anthropogenic climate change effects. On the other hand, however, if a temperature increase of 2.0 - 4.0 °C takes place at the end of the century as predicted by the Intergovernmental Panel on Climate Change (IPCC), it is likely that tropical species such as C. marleyi will become more common. Temperate species such as D. capensis and S. salpa were able to tolerate a wide range of temperatures (wide thermal scope) compared with the other fish species. These findings may suggest that D. capensis and S. salpa are thermally resilient and may be the least vulnerable to climate change effects and temperature variability. When evaluating the different life stages of D. capensis, however, using the dynamic method (juveniles and adults), static respirometry (juveniles) and maximum heart rate (adults), results suggested that juveniles of this temperate species will be more resilient to increases in ocean temperatures compared with the adults because they have a higher thermal tolerance (CTmax/TCRIT) and a greater metabolic scope (TOPT) at higher temperatures. For both juveniles and adults, temperatures beyond 28.0 °C (upper Tpej; Tarr) will have a significant impact on their physiology. Using a multi-scale and multi-method approach thus helped to identify which species or community may be vulnerable to the effects of climate change within shallow coastal environments in this warm-temperate climate change hotspot. Adopting this type of approach will assist policy makers in developing comprehensive climate change management frameworks for coastal ecosystems globally and around South Africa.
- Full Text:
- Date Issued: 2020
- Authors: Van der Walt, Kerry-Ann
- Date: 2020
- Subjects: Ectotherms -- Climatic factors , Ectotherms -- Effect of temperature on , Fishes -- Climatic factors , Fishes -- Effect of temperature on , Climatic changes -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/148459 , vital:38741
- Description: Temperature changes due to the effects of climate change are evident on all continents and oceans. As a result, there is a growing concern over how marine ectotherms will respond to extreme or fluctuating environmental temperatures. Temperature changes have strong direct and indirect effects on individual, population, and ecosystem functioning traits. A multi-scale approach determining the thermal tolerance and performance of several marine ectotherms belonging to different coastal habitats is rarely considered in thermal physiology studies but is effective for an integrated ecosystem assessment. As such, for this thesis, I aimed to quantify and compare the thermal tolerance and performance of a range of coastal marine ectotherms (fish and macro-invertebrates) with different biogeographical distributions from estuarine, subtidal and rocky intertidal habitats to available and projected in situ temperature data. This was also undertaken to gauge the local vulnerability of each species across summer and winter in a warm-temperate region of South Africa. This was done using a multi-method physiological approach, which included the dynamic method (CTmax and CTmin), static respirometry and maximum heart rate fHmax). Results of the dynamic method on several fish and macro-invertebrate species indicated that there are differences in thermal tolerance according to taxonomy, biogeography and habitat for both summer and winter. Macro-invertebrate species generally had higher CTmax endpoints, lower CTmin endpoints, higher upper and lower breadths in tolerance, higher upper and lower thermal safety margins and higher thermal scopes than the fish species. This could be a result of the macro-invertebrate species studied being less mobile compared with fish species (which are able to move to more favourable conditions) as well as having broader geographical distributions. In addition, macro-invertebrates from the intertidal rock pool habitat (Palaemon peringueyi; Pernaperna) were more tolerant of high and low temperatures compared with the macro-invertebrates from the estuarine habitat (Clibanarius virescens; Parasesarma catenatum; Upogebia africana). Overall, macro-invertebrates, with the exception of Parechinus angulosus, investigated in this study indicated that current temperatures and projected climate change scenarios across seasons would not have a significant impact on them and that they are highly adaptable to changing temperature regimes. This sign of high tolerance was further supported by the heart rates of P. perna and P. catenatum under an acute increase in temperature (1.0 °C.h-1) which showed individuals of each species physiologically depressing their metabolism until a final Arrhenius breakpoint temperature was reached (TAB). Among the fish species investigated in this study, tropical species (Chaetodon marleyi; Kuhlia mugil) had the highest CTmax and CTmin endpoints when compared with the temperate (Diplodus capensis; Sarpa salpa), warm-water endemic (Chelon dumerili; Rhabdosargus holubi) and cool-water endemic (Chelon richardsonii) fishes. This suggests that due to their lower breadths in tolerance and thermal safety margins being small, tropical species may be less tolerant of cold temperatures and thermal variability, especially in the form of summer upwelling events which are expected to increase in intensity and frequency in this region as a result of anthropogenic climate change effects. On the other hand, however, if a temperature increase of 2.0 - 4.0 °C takes place at the end of the century as predicted by the Intergovernmental Panel on Climate Change (IPCC), it is likely that tropical species such as C. marleyi will become more common. Temperate species such as D. capensis and S. salpa were able to tolerate a wide range of temperatures (wide thermal scope) compared with the other fish species. These findings may suggest that D. capensis and S. salpa are thermally resilient and may be the least vulnerable to climate change effects and temperature variability. When evaluating the different life stages of D. capensis, however, using the dynamic method (juveniles and adults), static respirometry (juveniles) and maximum heart rate (adults), results suggested that juveniles of this temperate species will be more resilient to increases in ocean temperatures compared with the adults because they have a higher thermal tolerance (CTmax/TCRIT) and a greater metabolic scope (TOPT) at higher temperatures. For both juveniles and adults, temperatures beyond 28.0 °C (upper Tpej; Tarr) will have a significant impact on their physiology. Using a multi-scale and multi-method approach thus helped to identify which species or community may be vulnerable to the effects of climate change within shallow coastal environments in this warm-temperate climate change hotspot. Adopting this type of approach will assist policy makers in developing comprehensive climate change management frameworks for coastal ecosystems globally and around South Africa.
- Full Text:
- Date Issued: 2020
Sediment connectivity in the upper Thina Catchment, Eastern Cape, South Africa
- Van der Waal, Benjamin Cornelis Wentsel
- Authors: Van der Waal, Benjamin Cornelis Wentsel
- Date: 2015
- Subjects: Soil erosion -- South Africa -- Eastern Cape , Sedimentation and deposition -- South Africa -- Eastern Cape , Watersheds -- South Africa -- Eastern Cape , Arroyos -- South Africa -- Eastern Cape , Sediment transport -- South Africa -- Eastern Cape , Soil conservation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4892 , http://hdl.handle.net/10962/d1019754
- Description: [Portion of abstract]: Sediment dynamics are influenced by transformed landscape connectivity in catchments worldwide. The upper Thina catchment, an important high rainfall resource in the northern Eastern Cape, South Africa, is an example of where ongoing subsistence farming on communal land has led to overgrazing and trampling that has initiated large erosive features (e.g. gullies) and river incision. The formation of gullies led to increased hillslope-channel connectivity and the resultant river incision decreased the channel-valley fill connectivity. These two changes in connectivity led to increased sediment export from the catchment that has various down-stream ecological and socio-economic impacts. This study investigates how the change in hillslope-channel and channel-valley fill connectivity has altered the sediment dynamics in the Vuvu catchment, a headwater tributary of the Thina River. A combination of methods were used to assess the changes in hillslope-channel and channel-valley fill connectivity. High resolution aerial images were used to map source features, such as fields, gullies, sheet erosion, landslides, roads and livestock tracks. Topographic and geological characteristics of the source features were extracted using a Geographic Information System. Furthermore, hillslope-channel pathways, such as the natural drainage network, continuous gullies, discontinuous gullies, roads and livestock tracks were mapped and analysed in terms of topographic and geological characteristics. Historic aerial images were assessed to calculate the date the larger gullies began forming. Recent aerial photos and cross sectional surveys of the valley fill were combined to map the various sediment sinks. Particle size and organic content were analysed for flood bench cores and terrace samples. The chronology of the flood benches was determined using unsupported Pb-210 and Cs-137 dating, and determined for the terraces using Optically Stimulated Luminescence dating. Quantitative and qualitative sediment tracing approaches, using mineral magnetic properties, were used to trace the origin of suspended sediment (collected during flood events), sediment stored in the flood benches and sediment stored in the terraces. Hydrological monitoring was used to assess the potential to store sediment on flood benches along the valley fill through flood bench inundation frequency. Hydrological and hydraulic modelling extended the measured inundation frequencies to a 73 year period and other cross sections along the valley fill. Furthermore, a future scenario of an increased vegetation cover and reduced hillslope-channel connectivity was assessed in terms of channel-valley fill inundation frequency.
- Full Text:
- Date Issued: 2015
- Authors: Van der Waal, Benjamin Cornelis Wentsel
- Date: 2015
- Subjects: Soil erosion -- South Africa -- Eastern Cape , Sedimentation and deposition -- South Africa -- Eastern Cape , Watersheds -- South Africa -- Eastern Cape , Arroyos -- South Africa -- Eastern Cape , Sediment transport -- South Africa -- Eastern Cape , Soil conservation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4892 , http://hdl.handle.net/10962/d1019754
- Description: [Portion of abstract]: Sediment dynamics are influenced by transformed landscape connectivity in catchments worldwide. The upper Thina catchment, an important high rainfall resource in the northern Eastern Cape, South Africa, is an example of where ongoing subsistence farming on communal land has led to overgrazing and trampling that has initiated large erosive features (e.g. gullies) and river incision. The formation of gullies led to increased hillslope-channel connectivity and the resultant river incision decreased the channel-valley fill connectivity. These two changes in connectivity led to increased sediment export from the catchment that has various down-stream ecological and socio-economic impacts. This study investigates how the change in hillslope-channel and channel-valley fill connectivity has altered the sediment dynamics in the Vuvu catchment, a headwater tributary of the Thina River. A combination of methods were used to assess the changes in hillslope-channel and channel-valley fill connectivity. High resolution aerial images were used to map source features, such as fields, gullies, sheet erosion, landslides, roads and livestock tracks. Topographic and geological characteristics of the source features were extracted using a Geographic Information System. Furthermore, hillslope-channel pathways, such as the natural drainage network, continuous gullies, discontinuous gullies, roads and livestock tracks were mapped and analysed in terms of topographic and geological characteristics. Historic aerial images were assessed to calculate the date the larger gullies began forming. Recent aerial photos and cross sectional surveys of the valley fill were combined to map the various sediment sinks. Particle size and organic content were analysed for flood bench cores and terrace samples. The chronology of the flood benches was determined using unsupported Pb-210 and Cs-137 dating, and determined for the terraces using Optically Stimulated Luminescence dating. Quantitative and qualitative sediment tracing approaches, using mineral magnetic properties, were used to trace the origin of suspended sediment (collected during flood events), sediment stored in the flood benches and sediment stored in the terraces. Hydrological monitoring was used to assess the potential to store sediment on flood benches along the valley fill through flood bench inundation frequency. Hydrological and hydraulic modelling extended the measured inundation frequencies to a 73 year period and other cross sections along the valley fill. Furthermore, a future scenario of an increased vegetation cover and reduced hillslope-channel connectivity was assessed in terms of channel-valley fill inundation frequency.
- Full Text:
- Date Issued: 2015
A personality-based surveillance model for Facebook apps
- Authors: Van der Schyff, Karl Izak
- Date: 2020
- Subjects: Facebook (Electronic resource) , Electronic surveillance -- Psychological aspects , Online social networks -- Psychological aspects , Social media -- Psychological aspects , Personality
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/145534 , vital:38447
- Description: The surveillance of data through the use of Facebook Apps is an ongoing and persistent problem that impacts millions of users. Nonetheless, limited research has been conducted investigating to what extent a Facebook user’s personality influences their awareness of such surveillance practices. Thus, to understand this situation better, the current study inductively developed four propositions from secondary data sources as part of a detailed content analysis. Spanning three search and analysis phases the content analysis led to the development of the research model. Guided by the propositions and research questions, a questionnaire was developed based on the relevant constructs prescribed by the Theory of Planned Behaviour. This questionnaire was used, and a total of 651 responses were collected from Facebook users over the age of 18 years old and residing in the United States of America. Primary data took place at both a univariate and multivariate level with a specific focus on the development of a structural model. Interpretation of the structural model revealed that out of all the Big Five personality traits, Conscientiousness exhibited the strongest relationship with information security awareness followed by Openness to Experience and Neuroticism, respectively. The results further indicated that the model constructs based on attitude, social norms and awareness significantly influenced the intended use of Facebook Apps. The study also contributes by indicating which personality traits are most vulnerable to Facebook App surveillance. For example, it was found that individuals high in Conscientiousness are the least vulnerable with individuals high in Extraversion being the most vulnerable. Since the results indicate that not all the personality traits are significantly related to the model constructs, additional factors may contribute to App surveillance in this context. Concerning this, factors such as user apathy, information privacy, privacy concerns, control and Facebook dependency are discussed as a means to argue why this might be the case.
- Full Text:
- Date Issued: 2020
- Authors: Van der Schyff, Karl Izak
- Date: 2020
- Subjects: Facebook (Electronic resource) , Electronic surveillance -- Psychological aspects , Online social networks -- Psychological aspects , Social media -- Psychological aspects , Personality
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/145534 , vital:38447
- Description: The surveillance of data through the use of Facebook Apps is an ongoing and persistent problem that impacts millions of users. Nonetheless, limited research has been conducted investigating to what extent a Facebook user’s personality influences their awareness of such surveillance practices. Thus, to understand this situation better, the current study inductively developed four propositions from secondary data sources as part of a detailed content analysis. Spanning three search and analysis phases the content analysis led to the development of the research model. Guided by the propositions and research questions, a questionnaire was developed based on the relevant constructs prescribed by the Theory of Planned Behaviour. This questionnaire was used, and a total of 651 responses were collected from Facebook users over the age of 18 years old and residing in the United States of America. Primary data took place at both a univariate and multivariate level with a specific focus on the development of a structural model. Interpretation of the structural model revealed that out of all the Big Five personality traits, Conscientiousness exhibited the strongest relationship with information security awareness followed by Openness to Experience and Neuroticism, respectively. The results further indicated that the model constructs based on attitude, social norms and awareness significantly influenced the intended use of Facebook Apps. The study also contributes by indicating which personality traits are most vulnerable to Facebook App surveillance. For example, it was found that individuals high in Conscientiousness are the least vulnerable with individuals high in Extraversion being the most vulnerable. Since the results indicate that not all the personality traits are significantly related to the model constructs, additional factors may contribute to App surveillance in this context. Concerning this, factors such as user apathy, information privacy, privacy concerns, control and Facebook dependency are discussed as a means to argue why this might be the case.
- Full Text:
- Date Issued: 2020
Creating a space for integrative education within the sciences
- Authors: Van der Post, Leda
- Date: 2012
- Subjects: Computer science -- Vocational guidance , Education, Cooperative , Curriculum evaluation , Experiential learning -- Science
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10482 , http://hdl.handle.net/10948/d1012677 , Computer science -- Vocational guidance , Education, Cooperative , Curriculum evaluation , Experiential learning -- Science
- Description: This thesis documents an action research project that was carried out within the Department of Computing Sciences at the Nelson Mandela Metropolitan University (NMMU), South Africa, from January 2010 to December 2011. The overall aim of the research was to foster an environment in which academics could explore ways to teach using an integrative approach to education. Previous research within the department had raised the concern that students were graduating without the type of high-level cognitive skills that were required in the workplace. While the students’ technical skills were perceived as being excellent, employers indicated that students would benefit from opportunities to develop or improve skills such as communication, teamwork, innovative thinking and time management. These skills include high-level cognitive skills, and are often referred to as “soft skills”. The academics participating in the research project came to believe that it was essential to develop teaching methods that would provide opportunities for students to develop these soft skills, in conjunction with the content and technical knowledge currently addressed in their courses. The research project followed the living theory approach to action research. A living theory action research project allows the researcher to investigate her own teaching, and develop a theory of practice. The theory of practice can be applied to the issues under investigation, to improve the situation or solve problems. At the same time, the theory of practice can contribute to the body of knowledge within the academic domain of the research. Action research is an iterative, cyclical process. There were four research cycles, each one semester in length, during the two years of the project. The project will continue, with a fifth research cycle, starting in January 2012. By the end of the fourth research cycle—Semester Two, 2011—there were eleven academics actively participating in the research group. The project had extended its influence to include academics from the Department of Mathematics at NMMU. The academics ranged from senior, long-serving professors to junior lecturing staff. The results of the research, or the researcher-practitioner’s living theory, explain the process by which an effective and enthusiastic community of practice, dedicated to improving the academics’ teaching and learning practice, was developed. The living theory is applicable to academics within a scientific discipline, desiring to explore and improve their education practice. My living theory explains the characteristics of the TLC (The Learning Community) space, and the action strategies for creating such a space. The explanation of the process of this project includes an analysis of the development process of the research group, typical characteristics of the environment or “space” of the group, and action strategies that other academics could use to create a similar community of practice.
- Full Text:
- Date Issued: 2012
- Authors: Van der Post, Leda
- Date: 2012
- Subjects: Computer science -- Vocational guidance , Education, Cooperative , Curriculum evaluation , Experiential learning -- Science
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10482 , http://hdl.handle.net/10948/d1012677 , Computer science -- Vocational guidance , Education, Cooperative , Curriculum evaluation , Experiential learning -- Science
- Description: This thesis documents an action research project that was carried out within the Department of Computing Sciences at the Nelson Mandela Metropolitan University (NMMU), South Africa, from January 2010 to December 2011. The overall aim of the research was to foster an environment in which academics could explore ways to teach using an integrative approach to education. Previous research within the department had raised the concern that students were graduating without the type of high-level cognitive skills that were required in the workplace. While the students’ technical skills were perceived as being excellent, employers indicated that students would benefit from opportunities to develop or improve skills such as communication, teamwork, innovative thinking and time management. These skills include high-level cognitive skills, and are often referred to as “soft skills”. The academics participating in the research project came to believe that it was essential to develop teaching methods that would provide opportunities for students to develop these soft skills, in conjunction with the content and technical knowledge currently addressed in their courses. The research project followed the living theory approach to action research. A living theory action research project allows the researcher to investigate her own teaching, and develop a theory of practice. The theory of practice can be applied to the issues under investigation, to improve the situation or solve problems. At the same time, the theory of practice can contribute to the body of knowledge within the academic domain of the research. Action research is an iterative, cyclical process. There were four research cycles, each one semester in length, during the two years of the project. The project will continue, with a fifth research cycle, starting in January 2012. By the end of the fourth research cycle—Semester Two, 2011—there were eleven academics actively participating in the research group. The project had extended its influence to include academics from the Department of Mathematics at NMMU. The academics ranged from senior, long-serving professors to junior lecturing staff. The results of the research, or the researcher-practitioner’s living theory, explain the process by which an effective and enthusiastic community of practice, dedicated to improving the academics’ teaching and learning practice, was developed. The living theory is applicable to academics within a scientific discipline, desiring to explore and improve their education practice. My living theory explains the characteristics of the TLC (The Learning Community) space, and the action strategies for creating such a space. The explanation of the process of this project includes an analysis of the development process of the research group, typical characteristics of the environment or “space” of the group, and action strategies that other academics could use to create a similar community of practice.
- Full Text:
- Date Issued: 2012
“Don’t be alarmed. It’s to do with sex.” Sherlock Holmes fanfiction and freedom of the imaginary domain
- Authors: van der Nest, Megan
- Date: 2020
- Subjects: Fan fiction , Fans (Persons) -- Fiction , Holmes, Sherlock , Literature and the internet , Sex in literature
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/124208 , vital:35576
- Description: In this thesis I argue that, for the individual fan, reading and writing fanfiction texts, and engaging with the online fandom communities within which these texts are produced, is a potentially valuable experience. This is because the kind of social and creative spaces found in these communities allow for, and celebrate, the free imaginative play with romantic and sexual desires, identities, and relationships. To articulate the importance of these spaces, I draw on Drucilla Cornell’s concept of the imaginary domain, defined as the psychic space each individual uses to explore different sexual desires and personae, which exploration is necessary for the development of full personhood. I also argue that the growing visibility and influence of fandom in modern society means that it could serve as a mechanism for social change, particularly in the acceptance and support of multiple sexual identities and forms of love. Selected texts, drawn from the Sherlock fandom, are discussed as representative of the approach taken within fanfiction communities towards various aspects of sexuality and sexual ethics. This approach combines the enthusiastic exploration of sexual desires without shame or fear of judgment with an ongoing, critical interrogation of sexual ethics.
- Full Text:
- Date Issued: 2020
- Authors: van der Nest, Megan
- Date: 2020
- Subjects: Fan fiction , Fans (Persons) -- Fiction , Holmes, Sherlock , Literature and the internet , Sex in literature
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/124208 , vital:35576
- Description: In this thesis I argue that, for the individual fan, reading and writing fanfiction texts, and engaging with the online fandom communities within which these texts are produced, is a potentially valuable experience. This is because the kind of social and creative spaces found in these communities allow for, and celebrate, the free imaginative play with romantic and sexual desires, identities, and relationships. To articulate the importance of these spaces, I draw on Drucilla Cornell’s concept of the imaginary domain, defined as the psychic space each individual uses to explore different sexual desires and personae, which exploration is necessary for the development of full personhood. I also argue that the growing visibility and influence of fandom in modern society means that it could serve as a mechanism for social change, particularly in the acceptance and support of multiple sexual identities and forms of love. Selected texts, drawn from the Sherlock fandom, are discussed as representative of the approach taken within fanfiction communities towards various aspects of sexuality and sexual ethics. This approach combines the enthusiastic exploration of sexual desires without shame or fear of judgment with an ongoing, critical interrogation of sexual ethics.
- Full Text:
- Date Issued: 2020
A phenomenological investigation into educational leaders' perceptions of themselves, their followers, and their organisational contexts
- Authors: Van der Mescht, Hennie
- Date: 1997
- Subjects: Educational leadership -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1697 , http://hdl.handle.net/10962/d1003580
- Description: Leadership is a richly researched ana widely covered topic, attracting the attention of virtually every discipline within the human sciences. Research which focuses on leadership within an educational context is, however, a relatively recent development. Most of the leadership research conducted in this century has been driven by the needs of industry. Consequently, leadership theories have tended to emphasise the instrumentality, measurability and effectiveness of leadership. Leadership models, intent on being prescriptive and 'learnable', have been inclined to oversimplify the complexity of the leadership phenomenon. Another factor which accounts for these features is the research approach adopted by researchers, which has largely been positivistic. This study is an attempt to investigate the underlying dynamics of educational leadership. It is an in-depth study of five educational leaders' perceptions of themselves as leaders, of the people with whom they interact, and of the organisations within which they work. The study is conducted along the lines suggested by phenomenology, a highly qualitative, anti-positivistic research approach, which encourages the researcher to set aside pre-conceived notions of the phenomenon, and to describe what is found exactly as it presents itself. My findings have highlighted a wide and richly varied range of psychological, emotional and cultural factors which seem to play significant roles in how leaders perceive themselves, others and their environments. Most of these factors have been either entirely ignored or very scantily covered in mainstream leadership literature. Educational leadership emerges as a complex, virtually undefinable phenomenon; new and challenging research approaches and methods have the potential for increasing our understanding of how leaders lead, which in turn will have implications for leadership education and selection.
- Full Text:
- Date Issued: 1997
- Authors: Van der Mescht, Hennie
- Date: 1997
- Subjects: Educational leadership -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1697 , http://hdl.handle.net/10962/d1003580
- Description: Leadership is a richly researched ana widely covered topic, attracting the attention of virtually every discipline within the human sciences. Research which focuses on leadership within an educational context is, however, a relatively recent development. Most of the leadership research conducted in this century has been driven by the needs of industry. Consequently, leadership theories have tended to emphasise the instrumentality, measurability and effectiveness of leadership. Leadership models, intent on being prescriptive and 'learnable', have been inclined to oversimplify the complexity of the leadership phenomenon. Another factor which accounts for these features is the research approach adopted by researchers, which has largely been positivistic. This study is an attempt to investigate the underlying dynamics of educational leadership. It is an in-depth study of five educational leaders' perceptions of themselves as leaders, of the people with whom they interact, and of the organisations within which they work. The study is conducted along the lines suggested by phenomenology, a highly qualitative, anti-positivistic research approach, which encourages the researcher to set aside pre-conceived notions of the phenomenon, and to describe what is found exactly as it presents itself. My findings have highlighted a wide and richly varied range of psychological, emotional and cultural factors which seem to play significant roles in how leaders perceive themselves, others and their environments. Most of these factors have been either entirely ignored or very scantily covered in mainstream leadership literature. Educational leadership emerges as a complex, virtually undefinable phenomenon; new and challenging research approaches and methods have the potential for increasing our understanding of how leaders lead, which in turn will have implications for leadership education and selection.
- Full Text:
- Date Issued: 1997
Positions on the mat : a micro-ethnographic study of teachers' and learners' co-construction of an early literacy practice
- Authors: Van der Mescht, Caroline
- Date: 2013 , 2013-06-10
- Subjects: Literacy -- Study and teaching (Primary) -- South Africa -- Eastern Cape English language -- Study and teaching (Primary) -- South Africa -- Eastern Cape English literature -- Study and teaching (Primary) -- South Africa -- Eastern Cape Education, Primary -- Research -- South Africa -- Eastern Cape Teachers -- Psychology Language and culture
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1836 , http://hdl.handle.net/10962/d1004333
- Description: Thesis embargoed until end of 2023. , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
- Authors: Van der Mescht, Caroline
- Date: 2013 , 2013-06-10
- Subjects: Literacy -- Study and teaching (Primary) -- South Africa -- Eastern Cape English language -- Study and teaching (Primary) -- South Africa -- Eastern Cape English literature -- Study and teaching (Primary) -- South Africa -- Eastern Cape Education, Primary -- Research -- South Africa -- Eastern Cape Teachers -- Psychology Language and culture
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1836 , http://hdl.handle.net/10962/d1004333
- Description: Thesis embargoed until end of 2023. , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
The nature and measurement of labour turnover
- Authors: Van der Merwe, Roux
- Date: 1970
- Subjects: Labor turnover -- South Africa , Industrial relations -- South Africa , Absenteeism (Labor) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3385 , http://hdl.handle.net/10962/d1013421
- Description: From the Introduction, p. 1-2. The main purposes of this study are to examine the methods by which one particular aspect of industrial behaviour, namely that of the worker's final withdrawal from the work situation, can be measured; to offer a more refined technique for the measurement of such withdrawals, and thirdly to attempt to relate this measurable phenomenon of withdrawal, commonly known as Labour Turnover, to the less easily measurable phenomenon of the integration of the individual worker into his working group. Labour Turnover - or the loss, over time, of employees from an employing organisation - is normally regarded as a province of study appropriate to the field of Industrial Psychology, and to its related applied field of Personnel Management. To a large extent, however, (as will be illustrated in Chapter II of this work) the results of such studies have proved inconclusive, and contradictory, and there is little evidence of progress towards a comprehensive understanding of the subject. This is undoubtedly due to the fragmentary nature of most studies in this field. These have generally been limited to the narrow confines of one particular aspect of the phenomenon, and consequently it has not been viewed against a sufficiently broad background.
- Full Text:
- Date Issued: 1970
- Authors: Van der Merwe, Roux
- Date: 1970
- Subjects: Labor turnover -- South Africa , Industrial relations -- South Africa , Absenteeism (Labor) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3385 , http://hdl.handle.net/10962/d1013421
- Description: From the Introduction, p. 1-2. The main purposes of this study are to examine the methods by which one particular aspect of industrial behaviour, namely that of the worker's final withdrawal from the work situation, can be measured; to offer a more refined technique for the measurement of such withdrawals, and thirdly to attempt to relate this measurable phenomenon of withdrawal, commonly known as Labour Turnover, to the less easily measurable phenomenon of the integration of the individual worker into his working group. Labour Turnover - or the loss, over time, of employees from an employing organisation - is normally regarded as a province of study appropriate to the field of Industrial Psychology, and to its related applied field of Personnel Management. To a large extent, however, (as will be illustrated in Chapter II of this work) the results of such studies have proved inconclusive, and contradictory, and there is little evidence of progress towards a comprehensive understanding of the subject. This is undoubtedly due to the fragmentary nature of most studies in this field. These have generally been limited to the narrow confines of one particular aspect of the phenomenon, and consequently it has not been viewed against a sufficiently broad background.
- Full Text:
- Date Issued: 1970
Aspects of the sentencing process in child sexual abuse cases
- Authors: Van der Merwe, Annette
- Date: 2006
- Subjects: Child sexual abuse -- South Africa , Sexually abused children -- Legal status, laws, etc -- South Africa , Child abuse -- Law and legislation -- South Africa , Sex crimes -- South Africa , Sentences(Criminal procedure) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3696 , http://hdl.handle.net/10962/d1003211 , Child sexual abuse -- South Africa , Sexually abused children -- Legal status, laws, etc -- South Africa , Child abuse -- Law and legislation -- South Africa , Sex crimes -- South Africa , Sentences(Criminal procedure) -- South Africa
- Description: This thesis investigates current sentencing practices relating to the diverse, complex and emotionally laden phenomenon of child sexual abuse. It focuses on relevant legislative provisions, on case law and on an empirical study conducted amongst regional court magistrates. Trends, developments and problems are analysed and possible solutions to the main problems identified are investigated. The thesis concludes with proposed guidelines regarding the sentencing process in child sexual abuse cases. Such guidelines address general and specific principles, the use of victim impact statements, the increased recognition and use of behavioural science in the sentencing phase with regard to both the victim and the offender, and relevant aggravating and mitigating factors. The guidelines are an attempt to give some structure to the current haphazard approach adopted by the courts with regard to harm experienced by the victim. They are also aimed at assisting experts to provide more effective and reliable pre-sentence reports. Further, the thesis attempts to provide clarity concerning the factors that are considered to be aggravating or mitigating in the offence category, child sexual abuse, as well as with regard to the weight that should be attached to them. In addition, recommendations are made for the purpose of possible law reform and further research in relation to the regulation of judicial discretion through the introduction of formal sentencing guidelines, victim impact statements and the accommodation of behavioural science in the sentencing process pertaining to sexual offenders. This proposal is based on current South African sentencing practices as reflected in the consolidation of local judgments scattered over many years in different law reports and, to some extent, on English, Canadian, Australian and American sentencing practices as researched in this study.
- Full Text:
- Date Issued: 2006
- Authors: Van der Merwe, Annette
- Date: 2006
- Subjects: Child sexual abuse -- South Africa , Sexually abused children -- Legal status, laws, etc -- South Africa , Child abuse -- Law and legislation -- South Africa , Sex crimes -- South Africa , Sentences(Criminal procedure) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3696 , http://hdl.handle.net/10962/d1003211 , Child sexual abuse -- South Africa , Sexually abused children -- Legal status, laws, etc -- South Africa , Child abuse -- Law and legislation -- South Africa , Sex crimes -- South Africa , Sentences(Criminal procedure) -- South Africa
- Description: This thesis investigates current sentencing practices relating to the diverse, complex and emotionally laden phenomenon of child sexual abuse. It focuses on relevant legislative provisions, on case law and on an empirical study conducted amongst regional court magistrates. Trends, developments and problems are analysed and possible solutions to the main problems identified are investigated. The thesis concludes with proposed guidelines regarding the sentencing process in child sexual abuse cases. Such guidelines address general and specific principles, the use of victim impact statements, the increased recognition and use of behavioural science in the sentencing phase with regard to both the victim and the offender, and relevant aggravating and mitigating factors. The guidelines are an attempt to give some structure to the current haphazard approach adopted by the courts with regard to harm experienced by the victim. They are also aimed at assisting experts to provide more effective and reliable pre-sentence reports. Further, the thesis attempts to provide clarity concerning the factors that are considered to be aggravating or mitigating in the offence category, child sexual abuse, as well as with regard to the weight that should be attached to them. In addition, recommendations are made for the purpose of possible law reform and further research in relation to the regulation of judicial discretion through the introduction of formal sentencing guidelines, victim impact statements and the accommodation of behavioural science in the sentencing process pertaining to sexual offenders. This proposal is based on current South African sentencing practices as reflected in the consolidation of local judgments scattered over many years in different law reports and, to some extent, on English, Canadian, Australian and American sentencing practices as researched in this study.
- Full Text:
- Date Issued: 2006
Paradoks as poësie: 'n ondersoek na enkele aspekte van die poësie van Breyten Breytenbach
- Authors: Van der Merwe, Anna Maria
- Date: 1975
- Subjects: Breytenbach, Breyten -- Criticism and interpretation
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3636 , http://hdl.handle.net/10962/d1013302
- Full Text:
- Date Issued: 1975
- Authors: Van der Merwe, Anna Maria
- Date: 1975
- Subjects: Breytenbach, Breyten -- Criticism and interpretation
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3636 , http://hdl.handle.net/10962/d1013302
- Full Text:
- Date Issued: 1975
"Complexes of carbohydrates with magnesium-ions" : "the isolation of an oligosaccharide containing L-galactose from the polysaccharide of Aeodes orbitosa" : "horizontal cellulose colum chromatography of sugars"
- Authors: Van der Linde, Michael John
- Date: 1974
- Subjects: Magenesium , Ions , Carbohydrates , Oligosaccharides , Polysaccharides , Chromatographic analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4504 , http://hdl.handle.net/10962/d1013282
- Description: Sugar complexes with anions and cations are reviewed. Evidence is presented for the formation of a complex of stoichiometry 1:1 in aqueous solution between methyl-α-Dglucopyranoside and magnesium perchlorate. The complex may be detected by the method of continuous variations. Measurements of changes in the proton chemical shifts of the glucoside in dauterium oxide, indicate that the complex is probably formed between the vicinal hydroxyl groups at C-2 and C-3 of the pyranoside ring and the hydrated cation. At elevation temperatures there is evidence for the presence of a complex of stoichiometry 2:1. Experiments conducted on cellulose indicate the possible formation of cellulose - magnesium-ion complexes . These complexes provide an explanation for the "protective action" of mEgnesium compounds on the cellulose portion of pulp during alkali-oxygen bleaching.
- Full Text:
- Date Issued: 1974
- Authors: Van der Linde, Michael John
- Date: 1974
- Subjects: Magenesium , Ions , Carbohydrates , Oligosaccharides , Polysaccharides , Chromatographic analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4504 , http://hdl.handle.net/10962/d1013282
- Description: Sugar complexes with anions and cations are reviewed. Evidence is presented for the formation of a complex of stoichiometry 1:1 in aqueous solution between methyl-α-Dglucopyranoside and magnesium perchlorate. The complex may be detected by the method of continuous variations. Measurements of changes in the proton chemical shifts of the glucoside in dauterium oxide, indicate that the complex is probably formed between the vicinal hydroxyl groups at C-2 and C-3 of the pyranoside ring and the hydrated cation. At elevation temperatures there is evidence for the presence of a complex of stoichiometry 2:1. Experiments conducted on cellulose indicate the possible formation of cellulose - magnesium-ion complexes . These complexes provide an explanation for the "protective action" of mEgnesium compounds on the cellulose portion of pulp during alkali-oxygen bleaching.
- Full Text:
- Date Issued: 1974