Log analysis aided by latent semantic mapping
- Authors: Buys, Stephanus
- Date: 2013 , 2013-04-14
- Subjects: Latent semantic indexing , Data mining , Computer networks -- Security measures , Computer hackers , Computer security
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4575 , http://hdl.handle.net/10962/d1002963 , Latent semantic indexing , Data mining , Computer networks -- Security measures , Computer hackers , Computer security
- Description: In an age of zero-day exploits and increased on-line attacks on computing infrastructure, operational security practitioners are becoming increasingly aware of the value of the information captured in log events. Analysis of these events is critical during incident response, forensic investigations related to network breaches, hacking attacks and data leaks. Such analysis has led to the discipline of Security Event Analysis, also known as Log Analysis. There are several challenges when dealing with events, foremost being the increased volumes at which events are often generated and stored. Furthermore, events are often captured as unstructured data, with very little consistency in the formats or contents of the events. In this environment, security analysts and implementers of Log Management (LM) or Security Information and Event Management (SIEM) systems face the daunting task of identifying, classifying and disambiguating massive volumes of events in order for security analysis and automation to proceed. Latent Semantic Mapping (LSM) is a proven paradigm shown to be an effective method of, among other things, enabling word clustering, document clustering, topic clustering and semantic inference. This research is an investigation into the practical application of LSM in the discipline of Security Event Analysis, showing the value of using LSM to assist practitioners in identifying types of events, classifying events as belonging to certain sources or technologies and disambiguating different events from each other. The culmination of this research presents adaptations to traditional natural language processing techniques that resulted in improved efficacy of LSM when dealing with Security Event Analysis. This research provides strong evidence supporting the wider adoption and use of LSM, as well as further investigation into Security Event Analysis assisted by LSM and other natural language or computer-learning processing techniques. , LaTeX with hyperref package , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Authors: Buys, Stephanus
- Date: 2013 , 2013-04-14
- Subjects: Latent semantic indexing , Data mining , Computer networks -- Security measures , Computer hackers , Computer security
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4575 , http://hdl.handle.net/10962/d1002963 , Latent semantic indexing , Data mining , Computer networks -- Security measures , Computer hackers , Computer security
- Description: In an age of zero-day exploits and increased on-line attacks on computing infrastructure, operational security practitioners are becoming increasingly aware of the value of the information captured in log events. Analysis of these events is critical during incident response, forensic investigations related to network breaches, hacking attacks and data leaks. Such analysis has led to the discipline of Security Event Analysis, also known as Log Analysis. There are several challenges when dealing with events, foremost being the increased volumes at which events are often generated and stored. Furthermore, events are often captured as unstructured data, with very little consistency in the formats or contents of the events. In this environment, security analysts and implementers of Log Management (LM) or Security Information and Event Management (SIEM) systems face the daunting task of identifying, classifying and disambiguating massive volumes of events in order for security analysis and automation to proceed. Latent Semantic Mapping (LSM) is a proven paradigm shown to be an effective method of, among other things, enabling word clustering, document clustering, topic clustering and semantic inference. This research is an investigation into the practical application of LSM in the discipline of Security Event Analysis, showing the value of using LSM to assist practitioners in identifying types of events, classifying events as belonging to certain sources or technologies and disambiguating different events from each other. The culmination of this research presents adaptations to traditional natural language processing techniques that resulted in improved efficacy of LSM when dealing with Security Event Analysis. This research provides strong evidence supporting the wider adoption and use of LSM, as well as further investigation into Security Event Analysis assisted by LSM and other natural language or computer-learning processing techniques. , LaTeX with hyperref package , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
Low symmetry metallophthalocyanines and their nanoparticle conjugates for photodynamic antimicrobial chemotherapy
- Authors: Masilela, Nkosiphile
- Date: 2013
- Subjects: Nanoparticles Anti-infective agents Chemotherapy Photochemotherapy Quantum dots Gold Silver , Phthalocyanines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4278 , http://hdl.handle.net/10962/d1001906
- Description: This thesis reports on the syntheses of novel low symmetrically substituted Zn, Sn, Ge and Ti MPc complexes containing a single carboxylic or cysteinyl group available for attachments to MNPs. The complexes were extensively characterized by various techniques to ensure their purity. Various metallic nanoparticles consisting of silver (AgNPs), gold (AuNPs) as well as quantum dots (QDs) were successfully prepared and conjugated to the low symmetry phthalocyanine complexes. The conjugates were successfully characterized using many techniques. The Q-band maxima of the MPcs were observed at completely different wavelength regions depending on the nature of the substituents and the central metal used. Blue shifting of the Q band in the absorption spectra was observed for the complexes in the presence of AuNPs, while aggregation was observed in the presence of quantum dots. The complexes were successfully electrospun into polymer fibers for the antimicrobial inhibition of bacteria. The photophysical and photochemical properties of these complexes were extensively investigated. Higher triplet and singlet oxygen quantum yields were achieved for the Ge Pc complexes, with all the complexes giving reasonable singlet oxygen quantum yields. An enhancement in triplet and singlet oxygen quantum yields was observed for all the complexes in the presence of metal nanoparticles. However, the singlet oxygen quantum yields decreased for all the complexes when incorporated into electrospun fibers. The antimicrobial behaviour of the complexes was investigated against Bacillus Subtilis and Staphylococcus Aureus in solution and in the fiber matrix. High antimicrobial inhibitions were observed for the Ge complexes followed by the ZnPc derivatives. All the low symmetry ZnPc derivatives were conjugated to AgNPs and their antimicrobial behaviour was compared to their symmetrical counterparts. The best antimicrobial inhibition behaviour was observed for the low symmetry Pcs when compared to their symmetrical counterparts. In the absence and in the presence of AgNPs, axially ligated SiPc also showed better antimicrobial activity when it was compared to the unsubstituted ZnPc complex.
- Full Text:
- Authors: Masilela, Nkosiphile
- Date: 2013
- Subjects: Nanoparticles Anti-infective agents Chemotherapy Photochemotherapy Quantum dots Gold Silver , Phthalocyanines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4278 , http://hdl.handle.net/10962/d1001906
- Description: This thesis reports on the syntheses of novel low symmetrically substituted Zn, Sn, Ge and Ti MPc complexes containing a single carboxylic or cysteinyl group available for attachments to MNPs. The complexes were extensively characterized by various techniques to ensure their purity. Various metallic nanoparticles consisting of silver (AgNPs), gold (AuNPs) as well as quantum dots (QDs) were successfully prepared and conjugated to the low symmetry phthalocyanine complexes. The conjugates were successfully characterized using many techniques. The Q-band maxima of the MPcs were observed at completely different wavelength regions depending on the nature of the substituents and the central metal used. Blue shifting of the Q band in the absorption spectra was observed for the complexes in the presence of AuNPs, while aggregation was observed in the presence of quantum dots. The complexes were successfully electrospun into polymer fibers for the antimicrobial inhibition of bacteria. The photophysical and photochemical properties of these complexes were extensively investigated. Higher triplet and singlet oxygen quantum yields were achieved for the Ge Pc complexes, with all the complexes giving reasonable singlet oxygen quantum yields. An enhancement in triplet and singlet oxygen quantum yields was observed for all the complexes in the presence of metal nanoparticles. However, the singlet oxygen quantum yields decreased for all the complexes when incorporated into electrospun fibers. The antimicrobial behaviour of the complexes was investigated against Bacillus Subtilis and Staphylococcus Aureus in solution and in the fiber matrix. High antimicrobial inhibitions were observed for the Ge complexes followed by the ZnPc derivatives. All the low symmetry ZnPc derivatives were conjugated to AgNPs and their antimicrobial behaviour was compared to their symmetrical counterparts. The best antimicrobial inhibition behaviour was observed for the low symmetry Pcs when compared to their symmetrical counterparts. In the absence and in the presence of AgNPs, axially ligated SiPc also showed better antimicrobial activity when it was compared to the unsubstituted ZnPc complex.
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Lʹétude des thèmes du deuil et de la marginalité dans Le Royaume Aveugle et Reine Pokou, concerto pour un sacrifice de Véronique Tadjo
- Sachikonye, Tsitsi Shamiso Anne
- Authors: Sachikonye, Tsitsi Shamiso Anne
- Date: 2013
- Subjects: Tadjo, Véronique -- Criticism and interpretation , West African literature (French) -- History and criticism , African fiction (French) -- 20th century
- Language: French
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3603 , http://hdl.handle.net/10962/d1002956 , Tadjo, Véronique -- Criticism and interpretation , West African literature (French) -- History and criticism , African fiction (French) -- 20th century
- Description: The field of our study is Francophone African Literature and this thesis explores the themes of marginality and grief both experienced by Princess Akissi in The Blind Kingdom and Princess Pokou in Queen Pokou (2004) during their rise to power in their respective kingdoms. The two novels written by Véronique Tadjo from Ivory Coast, are subjected to thematic analysis because they are both based on similar storylines - that of conflict and rivalry within kingdoms resulting in the exile of the two princesses. One of the novels is set in a pre-colonial period while the other is set in a postcolonial era. Queen Pokou, winner of the 2005 Grand Prix Littéraire d’Afrique Noire (which is the most distinguished prize in Francophone African literature), is a retelling of the founding myths of the Baoulé people of Ivory Coast. In her literary texts, Tadjo transgresses the original legend and her reconstruction of this legend is significant because it challenges the ritual sacrifice made by Princess Pokou in order to free her people and to become queen. In The Blind Kingdom (1990), Tadjo highlights the corruption and injustice of the ruling elite. Space is used to reinforce the King’s domination thus a revolution is necessary to overthrow the exploitative power structures in place. The revolution that takes place relies heavily on the participation of Karim and especially on Princess Akissi who chooses to rebel against her father, King Ato IV in order to stop injustice. This thematic analysis, supported by semiotic theory, aims to establish and demonstrate the relationship between marginality of the two princesses, in particular, and their subsequent grief. It sheds light on the reasons for their exclusion from power as well as the nature of the conflicts that occur as they rise to power. The study postulates that certain myths and images are evoked by the novelist to symbolise the exclusion of the two princesses from power.
- Full Text:
- Authors: Sachikonye, Tsitsi Shamiso Anne
- Date: 2013
- Subjects: Tadjo, Véronique -- Criticism and interpretation , West African literature (French) -- History and criticism , African fiction (French) -- 20th century
- Language: French
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3603 , http://hdl.handle.net/10962/d1002956 , Tadjo, Véronique -- Criticism and interpretation , West African literature (French) -- History and criticism , African fiction (French) -- 20th century
- Description: The field of our study is Francophone African Literature and this thesis explores the themes of marginality and grief both experienced by Princess Akissi in The Blind Kingdom and Princess Pokou in Queen Pokou (2004) during their rise to power in their respective kingdoms. The two novels written by Véronique Tadjo from Ivory Coast, are subjected to thematic analysis because they are both based on similar storylines - that of conflict and rivalry within kingdoms resulting in the exile of the two princesses. One of the novels is set in a pre-colonial period while the other is set in a postcolonial era. Queen Pokou, winner of the 2005 Grand Prix Littéraire d’Afrique Noire (which is the most distinguished prize in Francophone African literature), is a retelling of the founding myths of the Baoulé people of Ivory Coast. In her literary texts, Tadjo transgresses the original legend and her reconstruction of this legend is significant because it challenges the ritual sacrifice made by Princess Pokou in order to free her people and to become queen. In The Blind Kingdom (1990), Tadjo highlights the corruption and injustice of the ruling elite. Space is used to reinforce the King’s domination thus a revolution is necessary to overthrow the exploitative power structures in place. The revolution that takes place relies heavily on the participation of Karim and especially on Princess Akissi who chooses to rebel against her father, King Ato IV in order to stop injustice. This thematic analysis, supported by semiotic theory, aims to establish and demonstrate the relationship between marginality of the two princesses, in particular, and their subsequent grief. It sheds light on the reasons for their exclusion from power as well as the nature of the conflicts that occur as they rise to power. The study postulates that certain myths and images are evoked by the novelist to symbolise the exclusion of the two princesses from power.
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Mathematics teachers' experiences of designing and implementing a circle geometry teaching programme using the van Hiele phases of instruction as a conceptual framework: a Namibian case study
- Authors: Dongwi, Beata Lididimikeni
- Date: 2013
- Subjects: Geometry -- Study and teaching (Secondary) -- Namibia Mathematics -- Study and teaching -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1412 , http://hdl.handle.net/10962/d1003133
- Description: The aim of this case study was to examine, analyze and report on the findings of the experiences of selected mathematics teachers when they used the van Hiele phases of instruction in designing and implementing a Grade 11 circle geometry teaching programme. The sample consisted of three selected mathematics teachers from the school where the researcher teaches. This school is located in the Oshikoto Education Region in Namibia. The school serves a multicultural group of 759 learners from a middle-class economic background. The site and participants were selected conveniently as the researcher had unrestricted access to both the facilities and the participants. This research takes the form of a case study and is underpinned by the interpretive paradigm. Data for this research was collected using a variety of techniques such as interviews, classroom observation and document analysis. This facilitated easy triangulation of the data. The findings of this research make four claims with regard to the experiences of the mathematics teachers with designing and implementing the circle geometry teaching programme using the five van Hiele phases of instruction as a conceptual framework. The findings revealed that firstly, all three participating mathematics teachers used and implemented all the five van Hiele phases of instruction in their lessons I observed. Secondly, the teachers navigated quite freely from one phase of instruction to the next, but also returned to the earlier phases for clarification and reinforcement in their teaching. Thirdly, the teachers saw the phases of instruction as a good pedagogical tool or template for planning and presenting lessons. Fourthly, the majority of the learners followed the instructions and seemed to obtain the answers faster than expected. The lesson presentations were lively and both teachers and learners communicated at length to discover angle properties of circles while developing and nurturing the technical language of geometry.
- Full Text:
- Authors: Dongwi, Beata Lididimikeni
- Date: 2013
- Subjects: Geometry -- Study and teaching (Secondary) -- Namibia Mathematics -- Study and teaching -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1412 , http://hdl.handle.net/10962/d1003133
- Description: The aim of this case study was to examine, analyze and report on the findings of the experiences of selected mathematics teachers when they used the van Hiele phases of instruction in designing and implementing a Grade 11 circle geometry teaching programme. The sample consisted of three selected mathematics teachers from the school where the researcher teaches. This school is located in the Oshikoto Education Region in Namibia. The school serves a multicultural group of 759 learners from a middle-class economic background. The site and participants were selected conveniently as the researcher had unrestricted access to both the facilities and the participants. This research takes the form of a case study and is underpinned by the interpretive paradigm. Data for this research was collected using a variety of techniques such as interviews, classroom observation and document analysis. This facilitated easy triangulation of the data. The findings of this research make four claims with regard to the experiences of the mathematics teachers with designing and implementing the circle geometry teaching programme using the five van Hiele phases of instruction as a conceptual framework. The findings revealed that firstly, all three participating mathematics teachers used and implemented all the five van Hiele phases of instruction in their lessons I observed. Secondly, the teachers navigated quite freely from one phase of instruction to the next, but also returned to the earlier phases for clarification and reinforcement in their teaching. Thirdly, the teachers saw the phases of instruction as a good pedagogical tool or template for planning and presenting lessons. Fourthly, the majority of the learners followed the instructions and seemed to obtain the answers faster than expected. The lesson presentations were lively and both teachers and learners communicated at length to discover angle properties of circles while developing and nurturing the technical language of geometry.
- Full Text:
Mechanisms of luminescence in α-Al₂O₃:C : investigations using time-resolved optical stimulation and thermoluminescence techniques
- Authors: Nyirenda, Angel Newton
- Date: 2013
- Subjects: Thermoluminescence Aluminum oxide Optically stimulated luminescence dating Radiation dosimetry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5447 , http://hdl.handle.net/10962/d1002961
- Description: Carbon-doped aluminium oxide, α-Al₂O₃:C, is a ultra-sensitive dosimeter of topical research interest. The aim of this project was to investigate the dynamics of luminesce in this material. The methods of investigation consisted of thermoluminescence and time-resolved optical stimulation. Thermoluminescence measurements provide information on trap distribution and kinetic parameters of the traps involved in luminescence whereas time-resolved optical stimulation is a handy technique in investigation of luminescence lifetimes and provides an insight into the charge transitions between traps and recombination centres. Measurements were made on samples annealed at a nominal temperature of 900⁰C for 15 minutes. The material shows the presence of five thermoluminescence peaks at 37⁰C, 160⁰C, 300⁰C 410⁰C, and 480⁰C at a heating rate of 0.03k/s when irradiated to 6.0 Gy of beta. The main peak at 160⁰C, shows a linear dose response for doses between 0.1 Gy and 10 Gy and then goes sublinear above 10 Gy, the peak at 37⁰C shows a sublinear dose response for doses between 0.1 Gy and 10 Gy and appears to saturate thereafter, whereas the dose response of the peak at 300⁰C goes from linear to supralinear then apparently quadratic behaviour in the dose range of 0.1 Gy to 16.0 Gy. The trap depth of the main peak, that is, its activation energy as determined below the conduction band, has been approximated at 1.3 eV with a kinetic order of approximately 1.2. Time-resolved optical stimulation has been used to investigate luminescence lifetimes. The mean luminescence lifetime obtained for the sample at ambient temperatures is 35.0±1.0 ms. The investigations of the dependence of luminescence lifetimes on measurement temperature show that the material suffers from thermal quenching effects at measurement temperatures above 140⁰C with the activation energy of thermal quenching estimated at 1.045±0.002 eV. Shallow traps i.e. traps lying close to the conduction band, seem to elongate the lifetimes of optically stimulated luminescence in the material at temperatures between 30⁰C - 80⁰C due to charge retrapping. The material exhibits both fading and recuperation of the optically stimulated luminescence signal with storage time.
- Full Text:
- Authors: Nyirenda, Angel Newton
- Date: 2013
- Subjects: Thermoluminescence Aluminum oxide Optically stimulated luminescence dating Radiation dosimetry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5447 , http://hdl.handle.net/10962/d1002961
- Description: Carbon-doped aluminium oxide, α-Al₂O₃:C, is a ultra-sensitive dosimeter of topical research interest. The aim of this project was to investigate the dynamics of luminesce in this material. The methods of investigation consisted of thermoluminescence and time-resolved optical stimulation. Thermoluminescence measurements provide information on trap distribution and kinetic parameters of the traps involved in luminescence whereas time-resolved optical stimulation is a handy technique in investigation of luminescence lifetimes and provides an insight into the charge transitions between traps and recombination centres. Measurements were made on samples annealed at a nominal temperature of 900⁰C for 15 minutes. The material shows the presence of five thermoluminescence peaks at 37⁰C, 160⁰C, 300⁰C 410⁰C, and 480⁰C at a heating rate of 0.03k/s when irradiated to 6.0 Gy of beta. The main peak at 160⁰C, shows a linear dose response for doses between 0.1 Gy and 10 Gy and then goes sublinear above 10 Gy, the peak at 37⁰C shows a sublinear dose response for doses between 0.1 Gy and 10 Gy and appears to saturate thereafter, whereas the dose response of the peak at 300⁰C goes from linear to supralinear then apparently quadratic behaviour in the dose range of 0.1 Gy to 16.0 Gy. The trap depth of the main peak, that is, its activation energy as determined below the conduction band, has been approximated at 1.3 eV with a kinetic order of approximately 1.2. Time-resolved optical stimulation has been used to investigate luminescence lifetimes. The mean luminescence lifetime obtained for the sample at ambient temperatures is 35.0±1.0 ms. The investigations of the dependence of luminescence lifetimes on measurement temperature show that the material suffers from thermal quenching effects at measurement temperatures above 140⁰C with the activation energy of thermal quenching estimated at 1.045±0.002 eV. Shallow traps i.e. traps lying close to the conduction band, seem to elongate the lifetimes of optically stimulated luminescence in the material at temperatures between 30⁰C - 80⁰C due to charge retrapping. The material exhibits both fading and recuperation of the optically stimulated luminescence signal with storage time.
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Microsatellite and morphometric analysis of chokka squid (Loligo reynaudi) from different spawning aggregations around the South African coast
- Authors: Stonier, Terence Anthony
- Date: 2013
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5344 , http://hdl.handle.net/10962/d1006779
- Description: Accurate information on stock structure is very important to the effective management of any commercially exploited species (Angel et al. 1994), particularly in annual species like Loligo reynaudi. Previous molecular work on a number of fish and cephalopod species has shown that stock structuring may be more complex than originally believed and while much scientific work has been conducted on Loligo reynaudi to date, molecular work has been lacking and this species’ fishery is currently managed as a single stock. The primary aim of this project was to examine the population genetics of Loligo reynaudi on a molecular level, by looking at the levels of genetic variation between different spawning aggregations along the inshore distribution of the chokka squid, with particular attention being paid to any variation between Eastern Cape and Agulhas Bank groups. The secondary aim was to conduct a morphological analysis on samples from the same major areas in order to see if any genetic variation observed would be complemented by phenotypic variation. Two separate sample sets were collected; Genetic samples were collected from 6 different spawning sites along the South African Coast between April and July, 2006 and whole individuals for morphometric analysis were collected from 4 spawning sites between April and July 2007. Samples were screened for genetic variation between different spawning aggregations along the inshore distribution of chokka squid, from Port Alfred in the Eastern Cape, to the western Agulhas Bank. After this a morphometric analysis on samples from the same major areas, Eastern Cape, Agulhas Bank and Angola, was carried out. Genetic results showed significant variation between some of the sample groups. As expected, the Angolan outgroup consistently showed significant variation from other samples, while there was evidence of differentiation between the South African samples themselves. These results could have implications for the previously documented life cycle model of Loligo reynaudi and provide a basis for further study at a finer resolution into where exactly the boundaries of these different groupings can be found. This stock structuring has implications for the management of the species and warrants further genetic research with microsatellites proving to be a powerful tool in the explanation of stock structuring. Unfortunately, due to possible errors in taking measurements, morphometric analysis did not yield useful results which can be described and interpreted in this study. It is felt that further genetic study conducted on a finer scale, should be accompanied by a repeat of the morphometric analysis.
- Full Text:
- Authors: Stonier, Terence Anthony
- Date: 2013
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5344 , http://hdl.handle.net/10962/d1006779
- Description: Accurate information on stock structure is very important to the effective management of any commercially exploited species (Angel et al. 1994), particularly in annual species like Loligo reynaudi. Previous molecular work on a number of fish and cephalopod species has shown that stock structuring may be more complex than originally believed and while much scientific work has been conducted on Loligo reynaudi to date, molecular work has been lacking and this species’ fishery is currently managed as a single stock. The primary aim of this project was to examine the population genetics of Loligo reynaudi on a molecular level, by looking at the levels of genetic variation between different spawning aggregations along the inshore distribution of the chokka squid, with particular attention being paid to any variation between Eastern Cape and Agulhas Bank groups. The secondary aim was to conduct a morphological analysis on samples from the same major areas in order to see if any genetic variation observed would be complemented by phenotypic variation. Two separate sample sets were collected; Genetic samples were collected from 6 different spawning sites along the South African Coast between April and July, 2006 and whole individuals for morphometric analysis were collected from 4 spawning sites between April and July 2007. Samples were screened for genetic variation between different spawning aggregations along the inshore distribution of chokka squid, from Port Alfred in the Eastern Cape, to the western Agulhas Bank. After this a morphometric analysis on samples from the same major areas, Eastern Cape, Agulhas Bank and Angola, was carried out. Genetic results showed significant variation between some of the sample groups. As expected, the Angolan outgroup consistently showed significant variation from other samples, while there was evidence of differentiation between the South African samples themselves. These results could have implications for the previously documented life cycle model of Loligo reynaudi and provide a basis for further study at a finer resolution into where exactly the boundaries of these different groupings can be found. This stock structuring has implications for the management of the species and warrants further genetic research with microsatellites proving to be a powerful tool in the explanation of stock structuring. Unfortunately, due to possible errors in taking measurements, morphometric analysis did not yield useful results which can be described and interpreted in this study. It is felt that further genetic study conducted on a finer scale, should be accompanied by a repeat of the morphometric analysis.
- Full Text:
Modelling stock return volatility dynamics in selected African markets
- Authors: King, Daniel Jonathan
- Date: 2013
- Subjects: Rate of return -- Africa Stocks -- Prices -- Africa Finance -- Developing countries -- Econometric models
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1051 , http://hdl.handle.net/10962/d1006452
- Description: Stock return volatility has been shown to occasionally exhibit discrete structural shifts. These shifts are particularly evident in the transition from ‘normal’ to crisis periods, and tend to be more pronounced in developing markets. This study aims to establish whether accounting for structural changes in the conditional variance process, through the use of Markov-switching models, improves estimates and forecasts of stock return volatility over those of the more conventional single-state (G)ARCH models, within and across selected African markets for the period 2002-2012. In the univariate portion of the study, the performances of various Markov-switching models are tested against a single-state benchmark model through the use of in-sample goodness-of-fit and predictive ability measures. In the multivariate context, the single-state and Markov-switching models are comparatively assessed according to their usefulness in constructing optimal stock portfolios. It is found that, even after accounting for structural breaks in the conditional variance process, conventional GARCH effects remain important to capturing the heteroscedasticity evident in the data. However, those univariate models which include a GARCH term are shown to perform comparatively poorly when used for forecasting purposes. Additionally, in the multivariate study, the use of Markov-switching variance-covariance estimates improves risk-adjusted portfolio returns when compared to portfolios that are constructed using the more conventional single-state models. While there is evidence that the use of some Markov-switching models can result in better forecasts and higher risk-adjusted returns than those models which include GARCH effects, the inability of the simpler Markov-switching models to fully capture the heteroscedasticity in the data remains problematic.
- Full Text:
- Authors: King, Daniel Jonathan
- Date: 2013
- Subjects: Rate of return -- Africa Stocks -- Prices -- Africa Finance -- Developing countries -- Econometric models
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1051 , http://hdl.handle.net/10962/d1006452
- Description: Stock return volatility has been shown to occasionally exhibit discrete structural shifts. These shifts are particularly evident in the transition from ‘normal’ to crisis periods, and tend to be more pronounced in developing markets. This study aims to establish whether accounting for structural changes in the conditional variance process, through the use of Markov-switching models, improves estimates and forecasts of stock return volatility over those of the more conventional single-state (G)ARCH models, within and across selected African markets for the period 2002-2012. In the univariate portion of the study, the performances of various Markov-switching models are tested against a single-state benchmark model through the use of in-sample goodness-of-fit and predictive ability measures. In the multivariate context, the single-state and Markov-switching models are comparatively assessed according to their usefulness in constructing optimal stock portfolios. It is found that, even after accounting for structural breaks in the conditional variance process, conventional GARCH effects remain important to capturing the heteroscedasticity evident in the data. However, those univariate models which include a GARCH term are shown to perform comparatively poorly when used for forecasting purposes. Additionally, in the multivariate study, the use of Markov-switching variance-covariance estimates improves risk-adjusted portfolio returns when compared to portfolios that are constructed using the more conventional single-state models. While there is evidence that the use of some Markov-switching models can result in better forecasts and higher risk-adjusted returns than those models which include GARCH effects, the inability of the simpler Markov-switching models to fully capture the heteroscedasticity in the data remains problematic.
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Modulation of Plasmodium falciparum chaperones PfHsp70-1 and PfHsp70-x by small molecules
- Authors: Cockburn, Ingrid Louise
- Date: 2013
- Subjects: Plasmodium falciparum Heat shock proteins Molecular chaperones Homeostasis Protein folding Malaria Antimalarials Escherichia coli
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3887 , http://hdl.handle.net/10962/d1001747
- Description: The heat shock proteins of ~ 70 kDa (Hsp70s) are a conserved group of molecular chaperones important in maintaining the protein homeostasis in cells, carrying out functions including refolding of misfolded or unfolded proteins. Hsp70s function in conjunction with a number of other proteins including Hsp40 cochaperones. Central to the regulation Hsp70 activity is the Hsp70 ATPase cycle, involving ATP hydrolysis by Hsp70, and stimulation of this ATP hydrolysis by Hsp40. PfHsp70-1, the major cytosolic Hsp70 in the malaria parasite, Plasmodium falciparum, and PfHsp70-x, a novel malarial Hsp70 recently found to be exported to the host cell cytosol during the erythrocytic stages of the P. falciparum lifecycle, are both thought to play important roles in the malaria parasite’s survival and virulence, and thus represent novel antimalarial targets. Modulation of the function of these proteins by small molecules could thus lead to the development of antimalarials with novel targets and mechanisms. In the present study, malarial Hsp70s (PfHsp70-1 and PfHsp70-x), human Hsp70 (HSPA1A), malarial Hsp40 (PfHsp40) and human Hsp40 (Hsj1a) were recombinantly produced in Escherichia coli. In a characterisation of the chaperone activity of recombinant PfHsp70-x, the protein was found to have a basal ATPase activity (15.7 nmol ATP/min/mg protein) comparable to that previously described for PfHsp70-1, and an aggregation suppression activity significantly higher than that of PfHsp70-1. In vitro assays were used to screen five compounds of interest (lapachol, bromo-β-lapachona and malonganenones A, B and C) belonging to two compound classes (1,4 naphthoquinones and prenylated alkaloids) for modulatory effects on PfHsp70-1, PfHsp70-x and HsHsp70. A wide range of effects by compounds on the chaperone activities of Hsp70s was observed, including differential effects by compounds on different Hsp70s despite high conservation (≥ 70 % sequence identity) between the Hsp70s. The five compounds were shown to interact with all three Hsp70s in in vitro binding studies. Differential modulation by compounds was observed between the Hsj1a-stimulated ATPase activities of different Hsp70s, suggestive of not only a high degree of specificity of compounds to chaperone systems, but also distinct interactions between different Hsp70s and Hjs1a. The effects of compounds on the survival of P. falciparum parasites as well as mammalian cells was assessed. Bromo-β-lapachona was found to have broad effects across all systems, modulating the chaperone activities of all three Hsp70s, and showing significant toxicity toward both P. falciparum parasites and mammalian cells in culture. Malonganenone A was found to modulate only the malarial Hsp70s, not human Hsp70, showing significant toxicity toward malarial parasites (IC₅₀ ~ 0.8 μM), and comparatively low toxicity toward mammalian cells, representing therefore a novel starting point for a new class of antimalarials potentially targeting a new antimalarial drug target, Hsp70.
- Full Text:
- Authors: Cockburn, Ingrid Louise
- Date: 2013
- Subjects: Plasmodium falciparum Heat shock proteins Molecular chaperones Homeostasis Protein folding Malaria Antimalarials Escherichia coli
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3887 , http://hdl.handle.net/10962/d1001747
- Description: The heat shock proteins of ~ 70 kDa (Hsp70s) are a conserved group of molecular chaperones important in maintaining the protein homeostasis in cells, carrying out functions including refolding of misfolded or unfolded proteins. Hsp70s function in conjunction with a number of other proteins including Hsp40 cochaperones. Central to the regulation Hsp70 activity is the Hsp70 ATPase cycle, involving ATP hydrolysis by Hsp70, and stimulation of this ATP hydrolysis by Hsp40. PfHsp70-1, the major cytosolic Hsp70 in the malaria parasite, Plasmodium falciparum, and PfHsp70-x, a novel malarial Hsp70 recently found to be exported to the host cell cytosol during the erythrocytic stages of the P. falciparum lifecycle, are both thought to play important roles in the malaria parasite’s survival and virulence, and thus represent novel antimalarial targets. Modulation of the function of these proteins by small molecules could thus lead to the development of antimalarials with novel targets and mechanisms. In the present study, malarial Hsp70s (PfHsp70-1 and PfHsp70-x), human Hsp70 (HSPA1A), malarial Hsp40 (PfHsp40) and human Hsp40 (Hsj1a) were recombinantly produced in Escherichia coli. In a characterisation of the chaperone activity of recombinant PfHsp70-x, the protein was found to have a basal ATPase activity (15.7 nmol ATP/min/mg protein) comparable to that previously described for PfHsp70-1, and an aggregation suppression activity significantly higher than that of PfHsp70-1. In vitro assays were used to screen five compounds of interest (lapachol, bromo-β-lapachona and malonganenones A, B and C) belonging to two compound classes (1,4 naphthoquinones and prenylated alkaloids) for modulatory effects on PfHsp70-1, PfHsp70-x and HsHsp70. A wide range of effects by compounds on the chaperone activities of Hsp70s was observed, including differential effects by compounds on different Hsp70s despite high conservation (≥ 70 % sequence identity) between the Hsp70s. The five compounds were shown to interact with all three Hsp70s in in vitro binding studies. Differential modulation by compounds was observed between the Hsj1a-stimulated ATPase activities of different Hsp70s, suggestive of not only a high degree of specificity of compounds to chaperone systems, but also distinct interactions between different Hsp70s and Hjs1a. The effects of compounds on the survival of P. falciparum parasites as well as mammalian cells was assessed. Bromo-β-lapachona was found to have broad effects across all systems, modulating the chaperone activities of all three Hsp70s, and showing significant toxicity toward both P. falciparum parasites and mammalian cells in culture. Malonganenone A was found to modulate only the malarial Hsp70s, not human Hsp70, showing significant toxicity toward malarial parasites (IC₅₀ ~ 0.8 μM), and comparatively low toxicity toward mammalian cells, representing therefore a novel starting point for a new class of antimalarials potentially targeting a new antimalarial drug target, Hsp70.
- Full Text:
Money supply endogeneity : an empirical investigation of South African data (2000Q1-2011Q4)
- Authors: Schady, Stuart William
- Date: 2013 , 2013-04-29
- Subjects: Monetary policy -- South Africa , Inflation targeting -- South Africa , Gross domestic product -- South Africa , Bank loans -- South Africa , Money supply -- South Africa , Endogenous growth (Economics) , Domestic credit extension
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:928 , http://hdl.handle.net/10962/d1001454 , Monetary policy -- South Africa , Inflation targeting -- South Africa , Gross domestic product -- South Africa , Bank loans -- South Africa , Money supply -- South Africa , Endogenous growth (Economics)
- Description: This study is about whether the money supply in South Africa under a monetary policy regime of inflation‐targeting is exogenously or endogenously determined. The proposition of an exogenous money supply has been offered by monetarists, where the Central Bank determines the quantity of money supplied to the economy and this has a causal influence on income and credit extension. The endogenous money theory is a post‐Keynesian proposition whereby the money creation is determined by banks adjusting their responses to demands for credit‐money from economic agents. The data analysis is from 2000Q1 to 2010Q4 and entails the use of the variables monetary base (MB), domestic credit extension (DCE), M3, and gross national product (GDP). All variables are logged. The empirical tests conducted start with the Augmented Dickey‐Fuller unit root test to determine the variables order of integration. Johansen cointegration tests are done followed by Vector Error‐Correction Models (VECMs) and Granger causality tests to determine whether there is unidirectional or bidirectional causality between variables over the long and short‐run. Based on the results of the testing it was discovered that over the inflation‐targeting regime money supply in South Africa was endogenously determined. Furthermore, the data best supports the Accommodationist analysis of endogenous money as opposed to that of Structuralism and Liquidity Preference , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Authors: Schady, Stuart William
- Date: 2013 , 2013-04-29
- Subjects: Monetary policy -- South Africa , Inflation targeting -- South Africa , Gross domestic product -- South Africa , Bank loans -- South Africa , Money supply -- South Africa , Endogenous growth (Economics) , Domestic credit extension
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:928 , http://hdl.handle.net/10962/d1001454 , Monetary policy -- South Africa , Inflation targeting -- South Africa , Gross domestic product -- South Africa , Bank loans -- South Africa , Money supply -- South Africa , Endogenous growth (Economics)
- Description: This study is about whether the money supply in South Africa under a monetary policy regime of inflation‐targeting is exogenously or endogenously determined. The proposition of an exogenous money supply has been offered by monetarists, where the Central Bank determines the quantity of money supplied to the economy and this has a causal influence on income and credit extension. The endogenous money theory is a post‐Keynesian proposition whereby the money creation is determined by banks adjusting their responses to demands for credit‐money from economic agents. The data analysis is from 2000Q1 to 2010Q4 and entails the use of the variables monetary base (MB), domestic credit extension (DCE), M3, and gross national product (GDP). All variables are logged. The empirical tests conducted start with the Augmented Dickey‐Fuller unit root test to determine the variables order of integration. Johansen cointegration tests are done followed by Vector Error‐Correction Models (VECMs) and Granger causality tests to determine whether there is unidirectional or bidirectional causality between variables over the long and short‐run. Based on the results of the testing it was discovered that over the inflation‐targeting regime money supply in South Africa was endogenously determined. Furthermore, the data best supports the Accommodationist analysis of endogenous money as opposed to that of Structuralism and Liquidity Preference , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
Morphology, patterns and processes in the Oyster Bay headland bypass dunefield, South Africa
- Authors: McConnachie, Lauren Bernyse
- Date: 2013
- Subjects: Sand dune conservation -- South Africa -- Eastern Cape Sand dune ecology -- South Africa -- Eastern Cape Coastal ecology -- South Africa -- Eastern Cape Sedimentation and deposition -- South Africa -- Eastern Cape Beach erosion -- South Africa -- Eastern Cape Coastal zone management -- South Africa -- Eastern Cape Shore protection -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4804 , http://hdl.handle.net/10962/d1001904
- Description: Studies of the dunefield systems crossing the Cape St. Francis headland in the Eastern Cape have focused on the role that wind plays in sediment transfer in coastal dunefield systems, with limited consideration of the role of water. The aim of this study was to improve understanding of the morphology, processes and patterns within the Oyster Bay HBD system, focussing particularly on surface water and groundwater interactions and the role of surface water in sediment transfer across the dunefield system. An extensive field survey was conducted, to collect related data, complimented by spatial and temporal analysis of the study area using GIS. The key findings from this research were the apparent differences between the western and eastern regions of the dunefield with regard to specific drivers and the respective processes and responses. Wind is the major driver of change up to and across the crest of the dunefield. In the eastern region water (ground water, surface water and the Sand River System) is the primary agent of sediment flux through processes of aggregation and slumping as well as episodic events including debris flows. This study has highlighted a need for further quantitative studies that investigate the movement of sediment through dunefield systems such as this (where water is at or near the land surface). The paradigm that sediment flux is entirely due to wind is almost certainly simplistic, and deeper understanding of these systems is needed , Maiden name: Elkington, Lauren
- Full Text:
- Authors: McConnachie, Lauren Bernyse
- Date: 2013
- Subjects: Sand dune conservation -- South Africa -- Eastern Cape Sand dune ecology -- South Africa -- Eastern Cape Coastal ecology -- South Africa -- Eastern Cape Sedimentation and deposition -- South Africa -- Eastern Cape Beach erosion -- South Africa -- Eastern Cape Coastal zone management -- South Africa -- Eastern Cape Shore protection -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4804 , http://hdl.handle.net/10962/d1001904
- Description: Studies of the dunefield systems crossing the Cape St. Francis headland in the Eastern Cape have focused on the role that wind plays in sediment transfer in coastal dunefield systems, with limited consideration of the role of water. The aim of this study was to improve understanding of the morphology, processes and patterns within the Oyster Bay HBD system, focussing particularly on surface water and groundwater interactions and the role of surface water in sediment transfer across the dunefield system. An extensive field survey was conducted, to collect related data, complimented by spatial and temporal analysis of the study area using GIS. The key findings from this research were the apparent differences between the western and eastern regions of the dunefield with regard to specific drivers and the respective processes and responses. Wind is the major driver of change up to and across the crest of the dunefield. In the eastern region water (ground water, surface water and the Sand River System) is the primary agent of sediment flux through processes of aggregation and slumping as well as episodic events including debris flows. This study has highlighted a need for further quantitative studies that investigate the movement of sediment through dunefield systems such as this (where water is at or near the land surface). The paradigm that sediment flux is entirely due to wind is almost certainly simplistic, and deeper understanding of these systems is needed , Maiden name: Elkington, Lauren
- Full Text:
Morphology, patterns and processes in the Oyster Bay headland bypass dunefield, South Africa
- Authors: Elkington, Lauren
- Date: 2013
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:20984 , http://hdl.handle.net/10962/5879
- Description: Studies of the dunefield systems crossing the Cape St. Francis headland in the Eastern Cape have focused on the role that wind plays in sediment transfer in coastal dunefield systems, with limited consideration of the role of water. The aim of this study was to improve understanding of the morphology, processes and patterns within the Oyster Bay HBD system, focussing particularly on surface water and groundwater interactions and the role of surface water in sediment transfer across the dunefield system. An extensive field survey was conducted, to collect related data, complimented by spatial and temporal analysis of the study area using GIS. The key findings from this research were the apparent differences between the western and eastern regions of the dunefield with regard to specific drivers and the respective processes and responses. Wind is the major driver of change up to and across the crest of the dunefield. In the eastern region water (ground water, surface water and the Sand River System) is the primary agent of sediment flux through processes of aggregation and slumping as well as episodic events including debris flows. This study has highlighted a need for further quantitative studies that investigate the movement of sediment through dunefield systems such as this (where water is at or near the land surface). The paradigm that sediment flux is entirely due to wind is almost certainly simplistic, and deeper understanding of these systems is needed.
- Full Text:
- Authors: Elkington, Lauren
- Date: 2013
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:20984 , http://hdl.handle.net/10962/5879
- Description: Studies of the dunefield systems crossing the Cape St. Francis headland in the Eastern Cape have focused on the role that wind plays in sediment transfer in coastal dunefield systems, with limited consideration of the role of water. The aim of this study was to improve understanding of the morphology, processes and patterns within the Oyster Bay HBD system, focussing particularly on surface water and groundwater interactions and the role of surface water in sediment transfer across the dunefield system. An extensive field survey was conducted, to collect related data, complimented by spatial and temporal analysis of the study area using GIS. The key findings from this research were the apparent differences between the western and eastern regions of the dunefield with regard to specific drivers and the respective processes and responses. Wind is the major driver of change up to and across the crest of the dunefield. In the eastern region water (ground water, surface water and the Sand River System) is the primary agent of sediment flux through processes of aggregation and slumping as well as episodic events including debris flows. This study has highlighted a need for further quantitative studies that investigate the movement of sediment through dunefield systems such as this (where water is at or near the land surface). The paradigm that sediment flux is entirely due to wind is almost certainly simplistic, and deeper understanding of these systems is needed.
- Full Text:
Movement patterns and genetic stock delineation of an endemic South African sparid, the Poenskop, Cymatoceps nasutus (Castelnau, 1861)
- Authors: Murray, Taryn Sara
- Date: 2013
- Subjects: Fish stock assessment -- South Africa , Sparidae -- South Africa , Fishes -- Reproduction -- South Africa , Fishing -- South Africa , Fish populations -- South Africa , Fishes -- Behavior -- South Africa , Marine fishes -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5178 , http://hdl.handle.net/10962/d1001514 , Fish stock assessment -- South Africa , Sparidae -- South Africa , Fishes -- Reproduction -- South Africa , Fishing -- South Africa , Fish populations -- South Africa , Fishes -- Behavior -- South Africa , Marine fishes -- South Africa
- Description: Poenskop Cymatoceps nasutus (Pisces: Sparidae), an endemic South African sparid, is an important angling species being predominantly targeted by the recreational shore and skiboat sector. This species is slow-growing, long-lived, late-maturing and sex-changing, making poenskop acutely sensitive to over-exploitation. Despite interventions, such as the imposition of size and bag limits (currently 50 cm TL and one per licensed fisher per day) by authorities, catch-per-unit-effort trends reflect a severe and consistent stock decline over the last two decades. Poenskop has been identified as a priority species for research and conservation. Although the biology and population dynamics of this species have been well-documented, little is known about the movement behaviour of poenskop. Furthermore, there is a complete lack of information on its genetic stock structure. This thesis aimed to address the current knowledge gaps concerning movement behaviour and genetic stock structure of poenskop, making use of a range of methods and drawing on available information, including available fishery records as well as published and unpublished survey and research data, and data from long-term monitoring programmes. Analysis of available catch data (published and unpublished) revealed a decline in the number of poenskop caught as well as size of fish taken over the last two decades, ultimately reflecting the collapse of the stock (estimated to be at 20% of their pristine level). Improved catch-per-unit-effort data from the Tsitsikamma National Park Marine Protected Area (MPA), and larger poenskop being caught in the no-take areas than adjacent exploited areas of the Pondoland MPA confirmed that MPAs can be effective for the protection and management of poenskop. The current MPA network in South Africa is already wellestablished, and encompasses considerable reef areas, being preferable for poenskop habitation. Conventional dart tagging and recapture information from three ongoing, long-term fishtagging projects, conducted throughout the poenskop’s distribution, indicated high levels of residency at all life-history stages. Coastal region, seasonality and time at recapture did not appear to have a significant effect on the level of movement or distance moved. However, on examining the relationship among coastal movements and fish size and ages, larger and older fish (adults) moved greater distances, with juveniles and sub-adults showing high degrees of residency. An estimation of home-range size indicated smaller poenskop to hold smaller home-ranges, while larger poenskop hold larger home-ranges. Large easterly displacements of a number of adult poenskop is in accordance with previous findings that this species may undertake a unidirectional migration up the coastline of South Africa where they possibly settle in Transkei waters for the remainder of their lives. This high level of residency makes poenskop vulnerable to localised depletion, although they can be effectively protected by suitable MPAs. Despite considerable tagging effort along the South African coastline (2 704 poenskop tagged with 189 recaptures, between 1984 and 2010), there remains limited information on the connectivity of different regions along the South African coastline. This was addressed using mitochondrial DNA sequencing. The mitochondrial DNA control region was used due to its high substitution rate, haploid nature, maternal inheritance and absence of recombination. The mtDNA sequencing showed no evidence of major geographic barriers to gene flow in this species. Samples collected throughout the core distribution of poenskop showed high genetic diversity (h = 0.88, π = 0.01), low genetic differentiation among regions, no spatial structure (ɸST = 0.012, p = 0.208) and no evidence of isolation by distance. The collapsed stock status of poenskop as well as the fact that it is being actively targeted by recreational and commercial fishers suggests that this species requires improved management, with consideration given to its life-history style, residency and poor conservation status. Management recommendations for poenskop, combined with increasing South Africa’s existing MPA network, include the possibility of setting up a closed season (during known spawning periods) as well as the decommercialisation of this species. The techniques used and developed in this study can also be adopted for other overexploited linefish species.
- Full Text:
- Authors: Murray, Taryn Sara
- Date: 2013
- Subjects: Fish stock assessment -- South Africa , Sparidae -- South Africa , Fishes -- Reproduction -- South Africa , Fishing -- South Africa , Fish populations -- South Africa , Fishes -- Behavior -- South Africa , Marine fishes -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5178 , http://hdl.handle.net/10962/d1001514 , Fish stock assessment -- South Africa , Sparidae -- South Africa , Fishes -- Reproduction -- South Africa , Fishing -- South Africa , Fish populations -- South Africa , Fishes -- Behavior -- South Africa , Marine fishes -- South Africa
- Description: Poenskop Cymatoceps nasutus (Pisces: Sparidae), an endemic South African sparid, is an important angling species being predominantly targeted by the recreational shore and skiboat sector. This species is slow-growing, long-lived, late-maturing and sex-changing, making poenskop acutely sensitive to over-exploitation. Despite interventions, such as the imposition of size and bag limits (currently 50 cm TL and one per licensed fisher per day) by authorities, catch-per-unit-effort trends reflect a severe and consistent stock decline over the last two decades. Poenskop has been identified as a priority species for research and conservation. Although the biology and population dynamics of this species have been well-documented, little is known about the movement behaviour of poenskop. Furthermore, there is a complete lack of information on its genetic stock structure. This thesis aimed to address the current knowledge gaps concerning movement behaviour and genetic stock structure of poenskop, making use of a range of methods and drawing on available information, including available fishery records as well as published and unpublished survey and research data, and data from long-term monitoring programmes. Analysis of available catch data (published and unpublished) revealed a decline in the number of poenskop caught as well as size of fish taken over the last two decades, ultimately reflecting the collapse of the stock (estimated to be at 20% of their pristine level). Improved catch-per-unit-effort data from the Tsitsikamma National Park Marine Protected Area (MPA), and larger poenskop being caught in the no-take areas than adjacent exploited areas of the Pondoland MPA confirmed that MPAs can be effective for the protection and management of poenskop. The current MPA network in South Africa is already wellestablished, and encompasses considerable reef areas, being preferable for poenskop habitation. Conventional dart tagging and recapture information from three ongoing, long-term fishtagging projects, conducted throughout the poenskop’s distribution, indicated high levels of residency at all life-history stages. Coastal region, seasonality and time at recapture did not appear to have a significant effect on the level of movement or distance moved. However, on examining the relationship among coastal movements and fish size and ages, larger and older fish (adults) moved greater distances, with juveniles and sub-adults showing high degrees of residency. An estimation of home-range size indicated smaller poenskop to hold smaller home-ranges, while larger poenskop hold larger home-ranges. Large easterly displacements of a number of adult poenskop is in accordance with previous findings that this species may undertake a unidirectional migration up the coastline of South Africa where they possibly settle in Transkei waters for the remainder of their lives. This high level of residency makes poenskop vulnerable to localised depletion, although they can be effectively protected by suitable MPAs. Despite considerable tagging effort along the South African coastline (2 704 poenskop tagged with 189 recaptures, between 1984 and 2010), there remains limited information on the connectivity of different regions along the South African coastline. This was addressed using mitochondrial DNA sequencing. The mitochondrial DNA control region was used due to its high substitution rate, haploid nature, maternal inheritance and absence of recombination. The mtDNA sequencing showed no evidence of major geographic barriers to gene flow in this species. Samples collected throughout the core distribution of poenskop showed high genetic diversity (h = 0.88, π = 0.01), low genetic differentiation among regions, no spatial structure (ɸST = 0.012, p = 0.208) and no evidence of isolation by distance. The collapsed stock status of poenskop as well as the fact that it is being actively targeted by recreational and commercial fishers suggests that this species requires improved management, with consideration given to its life-history style, residency and poor conservation status. Management recommendations for poenskop, combined with increasing South Africa’s existing MPA network, include the possibility of setting up a closed season (during known spawning periods) as well as the decommercialisation of this species. The techniques used and developed in this study can also be adopted for other overexploited linefish species.
- Full Text:
New ways of understanding: a governmentality analysis of basic education policy in post-apartheid South Africa
- Authors: Prinsloo, Estelle Helena
- Date: 2013
- Subjects: South Africa -- Department of Basic Education , Basic education -- Government policy -- Research -- South Africa , Post-apartheid era -- Education -- South Africa , Educational change -- Research -- South Africa , South Africa -- Social conditions
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:2751 , http://hdl.handle.net/10962/d1001384
- Description: Social problems that are identified by government policy are articulated in ways that confer the responsibility of their management onto the state. In this way, policy reform serves as a means to justify political rule, as the ‘answers’ to policy failures are located within the realm of state intervention. This role of policy is maintained by the traditional definition of policy as it enables policies to be presented as the outcome of ‘necessary’ actions taken by state institutions to better the wellbeing of citizens. Since 1994, mainstream research on basic education policy in South Africa has employed traditional understandings of policy and its function. In doing so, these inquiries have failed to question the very idea of policy itself. They have also neglected to identify the productive role played by policy in the practice of power. To illuminate the necessary limits of policy reform, an alternative approach to analyse basic education policy is necessary. This thesis premises policy as discourse and advances a governmentality analysis of basic education policy during the first fifteen years of democracy (1994-2009) in South Africa. By drawing on the work of Michel Foucault, the study argues that government – ‘those actions upon the actions of others’ – during this period in South Africa was informed by both a liberal and a neo-liberal mentality of rule. The tensions between these two rationalities contributed to the continuation of apartheid’s socio-economic inequalities in the postapartheid era; an outcome buttressed by the contradictory impulses within basic education policy. By considering policy as a productive translation of governmental reasoning, the boundaries of intervention for future policy reforms are highlighted. These show that the inequalities that were perpetuated during the first fifteen years of democracy justify policy responses similar to those responsible for their production
- Full Text:
- Authors: Prinsloo, Estelle Helena
- Date: 2013
- Subjects: South Africa -- Department of Basic Education , Basic education -- Government policy -- Research -- South Africa , Post-apartheid era -- Education -- South Africa , Educational change -- Research -- South Africa , South Africa -- Social conditions
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:2751 , http://hdl.handle.net/10962/d1001384
- Description: Social problems that are identified by government policy are articulated in ways that confer the responsibility of their management onto the state. In this way, policy reform serves as a means to justify political rule, as the ‘answers’ to policy failures are located within the realm of state intervention. This role of policy is maintained by the traditional definition of policy as it enables policies to be presented as the outcome of ‘necessary’ actions taken by state institutions to better the wellbeing of citizens. Since 1994, mainstream research on basic education policy in South Africa has employed traditional understandings of policy and its function. In doing so, these inquiries have failed to question the very idea of policy itself. They have also neglected to identify the productive role played by policy in the practice of power. To illuminate the necessary limits of policy reform, an alternative approach to analyse basic education policy is necessary. This thesis premises policy as discourse and advances a governmentality analysis of basic education policy during the first fifteen years of democracy (1994-2009) in South Africa. By drawing on the work of Michel Foucault, the study argues that government – ‘those actions upon the actions of others’ – during this period in South Africa was informed by both a liberal and a neo-liberal mentality of rule. The tensions between these two rationalities contributed to the continuation of apartheid’s socio-economic inequalities in the postapartheid era; an outcome buttressed by the contradictory impulses within basic education policy. By considering policy as a productive translation of governmental reasoning, the boundaries of intervention for future policy reforms are highlighted. These show that the inequalities that were perpetuated during the first fifteen years of democracy justify policy responses similar to those responsible for their production
- Full Text:
Novel applications of Morita-Baylis-Hillman methodology in organic synthesis
- Authors: Mciteka, Lulama Patrick
- Date: 2013 , 2013-04-22
- Subjects: Organic compounds -- Synthesis -- Research Asymmetric synthesis Asymmetry (Chemistry) Chemical reactions -- Research Camphor -- Research AZT (Drug) -- Research Chemical inhibitors -- Research Chemistry -- Methodology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4439 , http://hdl.handle.net/10962/d1007598
- Description: The overall approach in the present investigation has been to explore applications of the Morita-Baylis-Hillman (MBH) reaction in asymmetric synthesis and in the continuation of systems with medicinal potential. To this end, a series of varied camphor-derived acrylate esters was prepared to serve as chiral substrates in asymmetric Morita-Baylis- Hillman reactions. Reduction of N-substituted camphor-10-sulfonamides afforded the 3- exo-hydroxy derivatives as the major products. Acylation of the corresponding sodium alkoxides gave the desired 3-exo-acrylate esters, isolation of which was complicated by concomitant formation of hydrochlorinated and diastereomeric competition products. Bulky camphorsulfonamides containing alkyl, dialkyl, aromatic and adamantyl groups were selected as N-substituents with the view of achieving stereoselective outcome in subsequent MBH reactions. The synthesis of novel camphor-derived Morita-Baylis-Hillman adducts using various pyridine-carboxaldehydes proceeded with exceptionally high yields with diastereoselectivities ranging from 7-33 % d.e. Both 1D and 2D NMR and HRMS techniques were employed to confirm the structures and an extensive study of the electropositive fragmentation patterns of a number of camphor-derived chiral acrylate esters was conducted. Attention has also been given to the application of MBH methodology in the construction of heterocyclic ‘cinnamate-like’ AZT conjugates which were designed to serve as dualaction HIV-1 integrase-reverse transcriptase (IN-RT) inhibitors. A number of pyridine carboxaldehyde-derived MBH adducts were synthesized using methyl, ethyl and t-butyl acrylates in the presence of 3-hydroxyquinuclidine (3-HQ) as catalyst. The yields for these reactions were excellent. The resulting MBH adducts were acetylated and subjected to aza-Michael addition using propargylamine. The resulting alkylamino compounds were then used in ‘Click reactions’ to form the targeted AZT-conjugates in moderate to excellent yield. In silico docking of computer modelled AZT-conjugates into the HIV-1 integrase and reverse transcriptase enzyme-active sites and potential hydrogen-bonding interaction with active-site amino acid residues were identified. The electrospray MS fragmentations of the AZT and the novel AZT-conjugates were also investigated and common fragmentation pathways were identified.
- Full Text:
- Authors: Mciteka, Lulama Patrick
- Date: 2013 , 2013-04-22
- Subjects: Organic compounds -- Synthesis -- Research Asymmetric synthesis Asymmetry (Chemistry) Chemical reactions -- Research Camphor -- Research AZT (Drug) -- Research Chemical inhibitors -- Research Chemistry -- Methodology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4439 , http://hdl.handle.net/10962/d1007598
- Description: The overall approach in the present investigation has been to explore applications of the Morita-Baylis-Hillman (MBH) reaction in asymmetric synthesis and in the continuation of systems with medicinal potential. To this end, a series of varied camphor-derived acrylate esters was prepared to serve as chiral substrates in asymmetric Morita-Baylis- Hillman reactions. Reduction of N-substituted camphor-10-sulfonamides afforded the 3- exo-hydroxy derivatives as the major products. Acylation of the corresponding sodium alkoxides gave the desired 3-exo-acrylate esters, isolation of which was complicated by concomitant formation of hydrochlorinated and diastereomeric competition products. Bulky camphorsulfonamides containing alkyl, dialkyl, aromatic and adamantyl groups were selected as N-substituents with the view of achieving stereoselective outcome in subsequent MBH reactions. The synthesis of novel camphor-derived Morita-Baylis-Hillman adducts using various pyridine-carboxaldehydes proceeded with exceptionally high yields with diastereoselectivities ranging from 7-33 % d.e. Both 1D and 2D NMR and HRMS techniques were employed to confirm the structures and an extensive study of the electropositive fragmentation patterns of a number of camphor-derived chiral acrylate esters was conducted. Attention has also been given to the application of MBH methodology in the construction of heterocyclic ‘cinnamate-like’ AZT conjugates which were designed to serve as dualaction HIV-1 integrase-reverse transcriptase (IN-RT) inhibitors. A number of pyridine carboxaldehyde-derived MBH adducts were synthesized using methyl, ethyl and t-butyl acrylates in the presence of 3-hydroxyquinuclidine (3-HQ) as catalyst. The yields for these reactions were excellent. The resulting MBH adducts were acetylated and subjected to aza-Michael addition using propargylamine. The resulting alkylamino compounds were then used in ‘Click reactions’ to form the targeted AZT-conjugates in moderate to excellent yield. In silico docking of computer modelled AZT-conjugates into the HIV-1 integrase and reverse transcriptase enzyme-active sites and potential hydrogen-bonding interaction with active-site amino acid residues were identified. The electrospray MS fragmentations of the AZT and the novel AZT-conjugates were also investigated and common fragmentation pathways were identified.
- Full Text:
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:
- 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:
On the implementation effectiveness and efficiency of ecological interventions in operational contexts : the case of Working for Water
- Authors: McConnachie, Matthew Morgan
- Date: 2013
- Subjects: Working for Water Programme Alien plants -- South Africa -- Eastern Cape Alien plants -- Control -- South Africa -- Eastern Cape Alien plants -- Control -- Cost effectiveness -- South Africa -- Eastern Cape Conservation of natural resources -- South Africa -- Eastern Cape Acacia mearnsii -- South Africa -- Eastern Cape Poverty -- South Africa -- Eastern Cape Revegetation -- South Africa -- Eastern Cape Restoration ecology -- South Africa -- Eastern Cape Environmental degradation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4729 , http://hdl.handle.net/10962/d1001956
- Description: There is little understanding of the implementation efficiency and effectiveness of restoring plant invaded landscapes within operational contexts. South Africa's Working for Water (WfW) programme is arguably the most ambitious alien plant control programme in the world, yet little is known about its cost-effectiveness and the challenges it faces in linking poverty and environmental objectives. My first aim was to assess the cost-effectiveness of invasive plant removal, and the factors that underpin its effectiveness over large spatial and temporal scales. The second aim was to compare the accuracy of evidence-based findings with managers' experience-based beliefs, and to assess whether managers are willing to change their beliefs after being exposed to it. The third aim was to assess the costs and benefits of removal versus removal followed by active native re-vegetation. My final aim is to assess the challenges and lessons learnt by managers linking ecological restoration with poverty alleviation objectives, specifically within the public works model. My study area was focused primarily on two WfW river catchment projects in the western region of the Eastern Cape province. I adopted an interdisciplinary approach drawing from a range of methods such as observational studies, statistical modelling and interviews with managers. The key findings were that control efforts in the two catchment projects are largely inadequate owing to many sites being re-invaded and not enough resources being allocated to the catchments. It would take between 54 and 695 years to clear the respective catchments. In terms of cost-effectiveness, my results exceeded previous estimates by 1.5 to 8.6 times for each catchment project. After being exposed to the evidence-based findings, the managers did not change their beliefs when it came to forecasting the future effectiveness. I found that active native re-vegetation after removal of invasive plants is very costly and that priority should be given to understanding the effectiveness of the removal treatments on native species recovery. The managers cited significant challenges in effectively and efficiently meeting the programmes dual objectives. Based on a broader review of the public works literature I recommend WfW re-examine the type of public works they currently use.
- Full Text:
- Authors: McConnachie, Matthew Morgan
- Date: 2013
- Subjects: Working for Water Programme Alien plants -- South Africa -- Eastern Cape Alien plants -- Control -- South Africa -- Eastern Cape Alien plants -- Control -- Cost effectiveness -- South Africa -- Eastern Cape Conservation of natural resources -- South Africa -- Eastern Cape Acacia mearnsii -- South Africa -- Eastern Cape Poverty -- South Africa -- Eastern Cape Revegetation -- South Africa -- Eastern Cape Restoration ecology -- South Africa -- Eastern Cape Environmental degradation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4729 , http://hdl.handle.net/10962/d1001956
- Description: There is little understanding of the implementation efficiency and effectiveness of restoring plant invaded landscapes within operational contexts. South Africa's Working for Water (WfW) programme is arguably the most ambitious alien plant control programme in the world, yet little is known about its cost-effectiveness and the challenges it faces in linking poverty and environmental objectives. My first aim was to assess the cost-effectiveness of invasive plant removal, and the factors that underpin its effectiveness over large spatial and temporal scales. The second aim was to compare the accuracy of evidence-based findings with managers' experience-based beliefs, and to assess whether managers are willing to change their beliefs after being exposed to it. The third aim was to assess the costs and benefits of removal versus removal followed by active native re-vegetation. My final aim is to assess the challenges and lessons learnt by managers linking ecological restoration with poverty alleviation objectives, specifically within the public works model. My study area was focused primarily on two WfW river catchment projects in the western region of the Eastern Cape province. I adopted an interdisciplinary approach drawing from a range of methods such as observational studies, statistical modelling and interviews with managers. The key findings were that control efforts in the two catchment projects are largely inadequate owing to many sites being re-invaded and not enough resources being allocated to the catchments. It would take between 54 and 695 years to clear the respective catchments. In terms of cost-effectiveness, my results exceeded previous estimates by 1.5 to 8.6 times for each catchment project. After being exposed to the evidence-based findings, the managers did not change their beliefs when it came to forecasting the future effectiveness. I found that active native re-vegetation after removal of invasive plants is very costly and that priority should be given to understanding the effectiveness of the removal treatments on native species recovery. The managers cited significant challenges in effectively and efficiently meeting the programmes dual objectives. Based on a broader review of the public works literature I recommend WfW re-examine the type of public works they currently use.
- Full Text:
Pedagogical ways-of-knowing in the design studio
- Authors: Kethro, Philippa
- Date: 2013
- Subjects: Graphic arts -- Education (Higher) Interior decoration -- Education (Higher) Fashion design -- Education (Higher) Industrial design -- Education (Higher) Aesthetics, Modern Art -- Philosophy Education, Higher -- Aims and objectives Interaction analysis in education Visual literacy Critical realism Communication and education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1840 , http://hdl.handle.net/10962/d1004338
- Description: This research addresses the effect of pedagogical ways-of-knowing in higher education design programmes such as Graphic Design, Interior Design, Fashion, and Industrial Design. One problematic aspect of design studio pedagogy is communication between teachers and students about the aesthetic visual meaning of the students’ designed objects. This problematic issue involves ambiguous and divergent ways-of-knowing the design meaning of these objects. The research focus is on the design teacher role in design studio interactions, and regards pedagogical ways-of-knowing as the ways in which teachers expect students to know visual design meaning. This pedagogical issue is complicated by the fact that there is no agreed-upon corpus of domain knowledge in design, so visual meaning depends greatly on the social knowledge retained by students and teachers. The thesis pursues an explanation of pedagogical ways-of-knowing that is approached through the philosophy of critical realism. How it is that particular events and experiences come to occur in a particular way is the general focus of critical realist philosophy. A critical realist approach to explanation is the use of abductive inference, or inference as to how it is that puzzling empirical circumstances emerge. An abductive strategy aims to explain how such circumstances emerge by considering them in a new light. This is done in this study by applying Luhmann’s theory of the emergence of cognition in communication to teacher ways-of-knowing in the design studio. Through the substantive use of Luhmann’s theory, an abductive conjecture of pedagogical ways-of-knowing is mounted. This conjecture is brought to bear on an examination of research data, in order to explain how pedagogical ways of-knowing constrain or enable the emergence of shared visual design meaning in the design studio. The abductive analysis explains three design pedagogical ways-of-knowing: design inquiry, design representation and design intent. These operate as macro relational mechanisms that either enable or constrain the emergence of shared visual design meaning in the design studio. The mechanism of relation is between design inquiry, design representation and design intent as historical knowing structures, and ways-of-knowing in respect of each of these knowing structures. For example, design inquiry as an historical knowing structure has over time moved from ways-of-knowing such as rationalistic problem solving to direct social observation and later to interpretive cultural analysis. The antecedence of these ways-of-knowing is important because communication about visual meaning depends upon prior knowledge, and teachers may then reproduce past ways-of-knowing. The many ways-of-knowing that respectively relate to design inquiry, design representation and design intent are shown to be communicatively formed and recursive over time. From a Luhmannian perspective, these ways-of-knowing operate as variational distinctions that indicate or relate to the knowing structures of design inquiry, design representation and design intent. This is the micro-level operation of pedagogical ways-of-knowing as relational mechanisms in design studio communication. Design teachers’ own ways-of-knowing may then embrace implicit way-of-knowing distinctions that indicate the knowledge structures of design inquiry, design representation and design intent. This implicit indication by distinction is the relational mechanism that may bring design teachers’ expectation that this and not that visual design meaning should apply in communication about any student’s designed object. Such an expectation influences communication between teachers and students about the potential future meaning of students’ designs. Consequently, shared visual design meaning may or may not emerge. The research explanation brings the opportunity for design teachers to make explicit the often implicit way-of-knowing distinctions they use, and to relate these distinctions to the knowing structures thus indicated. The study then offers a new perspective on the old design pedagogical problem of design studio conflict over the meaning of students’ designs. Options for applying this research explanation in design studio interactions between students and teachers are therefore suggested.
- Full Text:
- Authors: Kethro, Philippa
- Date: 2013
- Subjects: Graphic arts -- Education (Higher) Interior decoration -- Education (Higher) Fashion design -- Education (Higher) Industrial design -- Education (Higher) Aesthetics, Modern Art -- Philosophy Education, Higher -- Aims and objectives Interaction analysis in education Visual literacy Critical realism Communication and education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1840 , http://hdl.handle.net/10962/d1004338
- Description: This research addresses the effect of pedagogical ways-of-knowing in higher education design programmes such as Graphic Design, Interior Design, Fashion, and Industrial Design. One problematic aspect of design studio pedagogy is communication between teachers and students about the aesthetic visual meaning of the students’ designed objects. This problematic issue involves ambiguous and divergent ways-of-knowing the design meaning of these objects. The research focus is on the design teacher role in design studio interactions, and regards pedagogical ways-of-knowing as the ways in which teachers expect students to know visual design meaning. This pedagogical issue is complicated by the fact that there is no agreed-upon corpus of domain knowledge in design, so visual meaning depends greatly on the social knowledge retained by students and teachers. The thesis pursues an explanation of pedagogical ways-of-knowing that is approached through the philosophy of critical realism. How it is that particular events and experiences come to occur in a particular way is the general focus of critical realist philosophy. A critical realist approach to explanation is the use of abductive inference, or inference as to how it is that puzzling empirical circumstances emerge. An abductive strategy aims to explain how such circumstances emerge by considering them in a new light. This is done in this study by applying Luhmann’s theory of the emergence of cognition in communication to teacher ways-of-knowing in the design studio. Through the substantive use of Luhmann’s theory, an abductive conjecture of pedagogical ways-of-knowing is mounted. This conjecture is brought to bear on an examination of research data, in order to explain how pedagogical ways of-knowing constrain or enable the emergence of shared visual design meaning in the design studio. The abductive analysis explains three design pedagogical ways-of-knowing: design inquiry, design representation and design intent. These operate as macro relational mechanisms that either enable or constrain the emergence of shared visual design meaning in the design studio. The mechanism of relation is between design inquiry, design representation and design intent as historical knowing structures, and ways-of-knowing in respect of each of these knowing structures. For example, design inquiry as an historical knowing structure has over time moved from ways-of-knowing such as rationalistic problem solving to direct social observation and later to interpretive cultural analysis. The antecedence of these ways-of-knowing is important because communication about visual meaning depends upon prior knowledge, and teachers may then reproduce past ways-of-knowing. The many ways-of-knowing that respectively relate to design inquiry, design representation and design intent are shown to be communicatively formed and recursive over time. From a Luhmannian perspective, these ways-of-knowing operate as variational distinctions that indicate or relate to the knowing structures of design inquiry, design representation and design intent. This is the micro-level operation of pedagogical ways-of-knowing as relational mechanisms in design studio communication. Design teachers’ own ways-of-knowing may then embrace implicit way-of-knowing distinctions that indicate the knowledge structures of design inquiry, design representation and design intent. This implicit indication by distinction is the relational mechanism that may bring design teachers’ expectation that this and not that visual design meaning should apply in communication about any student’s designed object. Such an expectation influences communication between teachers and students about the potential future meaning of students’ designs. Consequently, shared visual design meaning may or may not emerge. The research explanation brings the opportunity for design teachers to make explicit the often implicit way-of-knowing distinctions they use, and to relate these distinctions to the knowing structures thus indicated. The study then offers a new perspective on the old design pedagogical problem of design studio conflict over the meaning of students’ designs. Options for applying this research explanation in design studio interactions between students and teachers are therefore suggested.
- Full Text:
Perceived usefulness of agricultural information sought on-line and broadcast in rural Mozambique: a case study of two Community Multimedia Centres (CMCs)
- Authors: Fuel, Isaias Carlos
- Date: 2013
- Subjects: Radio in community development -- Mozambique Radio broadcasting -- Mozambique Radio stations -- Mozambique Digital media -- Mozambique Rural development -- Mozambique Agriculture -- Mozambique
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3505 , http://hdl.handle.net/10962/d1007240
- Description: The wealth of information available on the Internet holds the potential to aid development in Africa. In order to be effective, such information needs to be contextualised to respond to local needs and practices. The combination of old and new media can support uptake and improve acceptance of new technologies in developing countries. The purpose of this qualitative study was to investigate the perceived usefulness of agricultural information sought on-line and broadcast via community radio in the two Community Multimedia Centres (CMCs) of Namaacha and Murrombene, in rural Mozambique. The data was generated from focus group discussion, individual interview, document analysis, and observation involving farmers and radio presenters. The study has shown that on-line agricultural information responds to the needs of the farmers because it contributes to eliminate pests and help farmers to make decisions about their activities. The study has also shown that there is a communication gap between farmers, extension workers, and volunteer reporters working at the community radios of the two CMCs. Volunteers have no agricultural knowledge. The problem this creates manifests itself primarily when they try to translate on-line agricultural information from Portuguese into local languages. Farmers have difficulties expressing their problems. Extension workers are not available to act as experts and mediators between volunteers and farmers. A collaborative website focusing on locally relevant content was suggested as a possible improvement.
- Full Text:
- Authors: Fuel, Isaias Carlos
- Date: 2013
- Subjects: Radio in community development -- Mozambique Radio broadcasting -- Mozambique Radio stations -- Mozambique Digital media -- Mozambique Rural development -- Mozambique Agriculture -- Mozambique
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3505 , http://hdl.handle.net/10962/d1007240
- Description: The wealth of information available on the Internet holds the potential to aid development in Africa. In order to be effective, such information needs to be contextualised to respond to local needs and practices. The combination of old and new media can support uptake and improve acceptance of new technologies in developing countries. The purpose of this qualitative study was to investigate the perceived usefulness of agricultural information sought on-line and broadcast via community radio in the two Community Multimedia Centres (CMCs) of Namaacha and Murrombene, in rural Mozambique. The data was generated from focus group discussion, individual interview, document analysis, and observation involving farmers and radio presenters. The study has shown that on-line agricultural information responds to the needs of the farmers because it contributes to eliminate pests and help farmers to make decisions about their activities. The study has also shown that there is a communication gap between farmers, extension workers, and volunteer reporters working at the community radios of the two CMCs. Volunteers have no agricultural knowledge. The problem this creates manifests itself primarily when they try to translate on-line agricultural information from Portuguese into local languages. Farmers have difficulties expressing their problems. Extension workers are not available to act as experts and mediators between volunteers and farmers. A collaborative website focusing on locally relevant content was suggested as a possible improvement.
- Full Text:
Performance management of veterinarians : a case study of veterinary services in the Eastern Cape
- Authors: Mutero, Gabriel
- Date: 2013
- Subjects: Performance management Veterinarians -- South Africa -- Rating of
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:719 , http://hdl.handle.net/10962/d1001873
- Description: In recent years, challenging economic conditions have stressed organizations, some to breaking point. Rather than waiting for external improvements, such as market growth or technological advances, many organizations are looking internally for performance and productivity gains (Boxall and Purcell, 2003). Consequently, the concept of performance management is receiving increased attention as a route to improved results and organisational growth (Boxall and Purcell, 2003). Likewise, increasing public pressure on governments to improve service delivery and account for the public purse have also forced many governments worldwide to implement a performance management system in one form or another (Ohemeng, 2009; Cameron and Sewell, 2003; Williams, 2005; Sehested, 2008). The South African Public Service has undergone much transformation since 2000. The transformation has been motivated by the Government’s realisation that, as with governments throughout the world, there is a need to modernise and professionalise all spheres of Government. The guiding principles for this transformation are contained in the White Paper on the Transformation of the Public Service (1995) and the Batho Pele White Paper (1997). This has informed the Public Service Act: Act 32 of 2000 of which stipulates that public service organisations should have a performance management system to promote a culture of performance management amongst all staff. The performance management system must ensure that the public service administers its affairs in an economical, effective, efficient and accountable manner. Whereas performance management systems have been in existence in some parts of the world since the early 1970s (Armstrong and Baron, 2005), in the Eastern Cape Provincial Government (ECPG) the Performance Management and Development System (PMDS) can be considered to still be in its infancy stage. It was introduced slightly over a decade ago, with the objective of managing performance in a consultative, supportive and non-discriminatory manner (ECPG, 2001). The PMDS also aims to provide clarity to all employees on their role in the achievement of departmental and provincial goals. This was anticipated to result in enhanced organisational efficiency and effectiveness, accountability for the use of resources and the achievement of results (ECPG, 2001). 4 A literature review contained in this research indicates that internationally and locally, implementing performance management systems is beset with challenges such as conflicting interests between different groups such as professionals wanting autonomy, organisational culture, poor implementation, lack of capacity and resources, lack of institutional and leadership support, changing workplace environments and many others. However it has also been shown that performance management systems are one way of ensuring that employees are focused, goals are met and organisation move forward toward meeting their mission. This research, which has been grounded within a post positivist paradigm, describes the impact of the PMDS on veterinarians in their professional conduct. Semi-structured interviews were conducted with ten veterinarians within the Department, culminating in a total of seven and a half hours of interviewing time. The findings of this study were that the PMDS was minimally effective in achieving organisational goals and mission because of several reasons such as inconsistency in application, perceived unfairness, a lack of ownership of the system amongst workers and management, a lack of involvement, a dichotomy between policy and actual practice, geographical remoteness of subordinates resulting in dilution of information and influence, lack of resources and finally, the type and validity of indicators used. A significant finding was that having a non-veterinarian as a supervisor, impacted negatively on professional conduct. This was perceived to affect planning and goal setting, review and feedback discussions, as well as career advancement. The research ends with recommendations for practice and further research such as exploring management of professionals in multidisciplinary organisations. This research paper is organised and presented in three sections; the first section is in the format of an academic paper, and in addition to a concise review of the literature, will detail the findings, their discussion and conclusion. The second section contains a more expanded literature review of performance management of professionals and the third and last section describes and justifies the design of the study and how it was conducted.
- Full Text:
- Authors: Mutero, Gabriel
- Date: 2013
- Subjects: Performance management Veterinarians -- South Africa -- Rating of
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:719 , http://hdl.handle.net/10962/d1001873
- Description: In recent years, challenging economic conditions have stressed organizations, some to breaking point. Rather than waiting for external improvements, such as market growth or technological advances, many organizations are looking internally for performance and productivity gains (Boxall and Purcell, 2003). Consequently, the concept of performance management is receiving increased attention as a route to improved results and organisational growth (Boxall and Purcell, 2003). Likewise, increasing public pressure on governments to improve service delivery and account for the public purse have also forced many governments worldwide to implement a performance management system in one form or another (Ohemeng, 2009; Cameron and Sewell, 2003; Williams, 2005; Sehested, 2008). The South African Public Service has undergone much transformation since 2000. The transformation has been motivated by the Government’s realisation that, as with governments throughout the world, there is a need to modernise and professionalise all spheres of Government. The guiding principles for this transformation are contained in the White Paper on the Transformation of the Public Service (1995) and the Batho Pele White Paper (1997). This has informed the Public Service Act: Act 32 of 2000 of which stipulates that public service organisations should have a performance management system to promote a culture of performance management amongst all staff. The performance management system must ensure that the public service administers its affairs in an economical, effective, efficient and accountable manner. Whereas performance management systems have been in existence in some parts of the world since the early 1970s (Armstrong and Baron, 2005), in the Eastern Cape Provincial Government (ECPG) the Performance Management and Development System (PMDS) can be considered to still be in its infancy stage. It was introduced slightly over a decade ago, with the objective of managing performance in a consultative, supportive and non-discriminatory manner (ECPG, 2001). The PMDS also aims to provide clarity to all employees on their role in the achievement of departmental and provincial goals. This was anticipated to result in enhanced organisational efficiency and effectiveness, accountability for the use of resources and the achievement of results (ECPG, 2001). 4 A literature review contained in this research indicates that internationally and locally, implementing performance management systems is beset with challenges such as conflicting interests between different groups such as professionals wanting autonomy, organisational culture, poor implementation, lack of capacity and resources, lack of institutional and leadership support, changing workplace environments and many others. However it has also been shown that performance management systems are one way of ensuring that employees are focused, goals are met and organisation move forward toward meeting their mission. This research, which has been grounded within a post positivist paradigm, describes the impact of the PMDS on veterinarians in their professional conduct. Semi-structured interviews were conducted with ten veterinarians within the Department, culminating in a total of seven and a half hours of interviewing time. The findings of this study were that the PMDS was minimally effective in achieving organisational goals and mission because of several reasons such as inconsistency in application, perceived unfairness, a lack of ownership of the system amongst workers and management, a lack of involvement, a dichotomy between policy and actual practice, geographical remoteness of subordinates resulting in dilution of information and influence, lack of resources and finally, the type and validity of indicators used. A significant finding was that having a non-veterinarian as a supervisor, impacted negatively on professional conduct. This was perceived to affect planning and goal setting, review and feedback discussions, as well as career advancement. The research ends with recommendations for practice and further research such as exploring management of professionals in multidisciplinary organisations. This research paper is organised and presented in three sections; the first section is in the format of an academic paper, and in addition to a concise review of the literature, will detail the findings, their discussion and conclusion. The second section contains a more expanded literature review of performance management of professionals and the third and last section describes and justifies the design of the study and how it was conducted.
- Full Text:
Petrogenesis and metallogenesis of the Panzhihua Fe-Ti oxide ore-bearing mafic layered intrusion, SW China
- Authors: Howarth, Geoffrey Hamilton
- Date: 2013
- Subjects: Petrogenesis Metallogeny Intrusions (Geology) -- China -- Panzhihua Metallogenic provinces -- China -- Panzhihua Igneous rocks -- China -- Panzhihua Geochemistry Iron Titanium Oxides Ores Magmas
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4915 , http://hdl.handle.net/10962/d1001810
- Description: The Panzhihua intrusion is one of several large Fe-Ti oxide ore bearing intrusions related to the major flood volcanism of the Emeishan Large Igneous Province (ELIP), SW China. The Panzhihua intrusion in particular has recently become the focus of numerous studies owing to the excellent exposure in large open pit mining operations. The formation of Fe-Ti oxide ore layers has been the focus of these studies and has become a somewhat controversial topic with three separate models currently proposed for ore formation. The gabbroic Panzhihua intrusion extends for ± 19 km along strike, has a maximum thickness of 3000 m and hosts extensive (up to 60 m thick) Fe-Ti oxide ore layers in the lower portions of the intrusion. The intrusion has been divided into five zones: marginal zone (MGZ), lower zone (LZ), middle zone A (MZa), middle zone b (MZb) and the upper zone (UZ). The gabbroic rocks are comprised of plagioclase, clinopyroxene and interstitial Fe-Ti oxides with minor olivine. Apatite is present within the MZb only and shows no correlation with Fe-Ti oxide ore layers. Fe-Ti oxides are present throughout the stratigraphy of the intrusion. This is unlike typical layered intrusions where significant Fe-enrichment through fractionation of Fe-poor silicate phases (i.e. plagioclase) is required before Fe-Ti oxide saturation. There are no oxide-free cumulate rocks at the Panzhihua intrusion, implying either an evolved parent magma or very high Fe content of the source rocks. I present here new mineral composition data, whole-rock major and trace element geochemistry along with whole-rock Sr-Nd isotopes and PGEs in order to constrain the evolution of the Panzhihua parent magma en route from source to chamber and the formation of Fe-Ti oxide ore layers. Furthermore an initial pilot study using O-isotope data is conducted on Ti-magnetite and plagioclase separates from gabbroic vs. ore rocks. Results are coupled with detailed thermodynamic modeling using the software PELE in order to further constrain Fe-Ti oxide ore layer formation. The intrusion is characterised by extreme depletion of PGEs relative to the coeval flood basalts and picrites. High Cu/Pd and Pd/Pt imply two separate stages of S-saturated and S-undersaturated depletion of PGEs. Pd is highly compatible in sulphide and is quickly scavenged by sulphide liquids resulting in an increase in Cu/Pd of the residual liquid. Furthermore decoupling of Pd and Pt can be achieved by either late stage hydrothermal alteration or through S-undersaturated stage of PGE depletion where Pt is scavenged by Pt-rich alloys or oxide minerals. I show that the latter is more likely. Fractionation modeling suggests that the Panzhihua parent magma formed at depth from original picritic magma. This is consistent with several other recent studies on other layered intrusions of the ELIP. Sr-Nd isotopic ratios indicate very little crustal contamination has occurred en route to the current chamber. Sr and Nd concentrations of footwall rocks are too low to produce any significant change in initial Sr and Nd isotopic ratios of the intruding basaltic magmas, indicating that crustal contamination will not be indicated by Sr-Nd isotopic ratios. Gradational change in the Sr-Nd isotope ratios across the MGZ provides strong evidence for formation in an open system by multiple replenishments of progressively less contaminated magmas from depth. Contamination is difficult to constrain but must be occurring prior to emplacement at the current level (low Sr and Nd contents of footwall). A gradational upward decrease in highly incompatible element across the MGZ can then be explained by continuous magma flow, which effectively removes the evolved intercumulus liquids from the growing cumulate pile at the base of the chamber. The initial stages of formation of the Panzhihua intrusion are interpreted to result from prolonged low volume pulses of magma into a slowly opening chamber. The timing of Fe-Ti oxide crystallisation is fundamental in the understanding of the petrogenesis of ore layers. Distinct geochemical variation in whole-rock Fe2O3/TiO2 and Zr/Nb indicates that Timagnetite is the dominant oxide within the lower ± 270 m of the intrusion whereas above this level both Ti-magnetite and ilmenite are present as cumulus phases. This is interpreted to indicate a variation in the fO2 where the lower intrusion crystallises at higher fO2 relative to that above this level. Silicates within the ore layers, in particular plagioclase, are highly embayed and resorped where in contact with Fe-Ti oxides. This characteristic of the silicate grains implies early crystallisation prior to Fe-Ti oxides with subsequent disequilibrium conditions resulting in resorption. Furthermore distinct reaction rims of kaersutite amphibole, Fo-enriched olivine, An-enriched plagioclase and pleonaste are observed. The abundance of amphibole suggests H2O involvement in this reaction and consumption of silicates. A model for parent magma crystallisation at various H2O contents indicates that plagioclase crystallisation temperature is very sensitive to H2O content of the parent magma. Plagioclase crystallises early for “dry” compositions but significantly later for “wet” compositions. Fe-Ti oxide ore layers are generally well layered, contain gabbroic xenoliths and are observed raversing/cross-cutting the cumulate stratigraphy. I present here a new model for ore layer formation in order to account for these distinct features of the ore layers. A model invoking multiple replenishments of magma with variable oxide microphenocryst content, H2O content and volume is proposed. Magma evolving in the plumbing system and fed to the Panzhihua chamber is variably enriched in H2O, which results in significantly different crystallisation paths. High H2O magmas (> 2 wt %) crystallise Fe-Ti oxides early whereas low H2O magmas (< 1 wt %) crystallise oxides late. Early pulses of H2O-poor magma crystallise a sequence of plag+cpx+Fe-Ti oxide (±ol). Later pulses of H2Orich magma subsequently intrude the partially crystallised cumulate sequence incorporating and consuming previously crystallised silicates with subsequent early crystallisation of Ti-magnetite and formation of ore layers. H2O-rich magmas likely have suspended Ti-magnetite microphenocrysts as well, which crystallise at depth in the plumbing system. This model can account for the various characteristic features of the Fe-Ti oxide ore layers at the Panzhihua intrusion as well as other Fe-Ti oxide ore bearing intrusions in the region.
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- Authors: Howarth, Geoffrey Hamilton
- Date: 2013
- Subjects: Petrogenesis Metallogeny Intrusions (Geology) -- China -- Panzhihua Metallogenic provinces -- China -- Panzhihua Igneous rocks -- China -- Panzhihua Geochemistry Iron Titanium Oxides Ores Magmas
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4915 , http://hdl.handle.net/10962/d1001810
- Description: The Panzhihua intrusion is one of several large Fe-Ti oxide ore bearing intrusions related to the major flood volcanism of the Emeishan Large Igneous Province (ELIP), SW China. The Panzhihua intrusion in particular has recently become the focus of numerous studies owing to the excellent exposure in large open pit mining operations. The formation of Fe-Ti oxide ore layers has been the focus of these studies and has become a somewhat controversial topic with three separate models currently proposed for ore formation. The gabbroic Panzhihua intrusion extends for ± 19 km along strike, has a maximum thickness of 3000 m and hosts extensive (up to 60 m thick) Fe-Ti oxide ore layers in the lower portions of the intrusion. The intrusion has been divided into five zones: marginal zone (MGZ), lower zone (LZ), middle zone A (MZa), middle zone b (MZb) and the upper zone (UZ). The gabbroic rocks are comprised of plagioclase, clinopyroxene and interstitial Fe-Ti oxides with minor olivine. Apatite is present within the MZb only and shows no correlation with Fe-Ti oxide ore layers. Fe-Ti oxides are present throughout the stratigraphy of the intrusion. This is unlike typical layered intrusions where significant Fe-enrichment through fractionation of Fe-poor silicate phases (i.e. plagioclase) is required before Fe-Ti oxide saturation. There are no oxide-free cumulate rocks at the Panzhihua intrusion, implying either an evolved parent magma or very high Fe content of the source rocks. I present here new mineral composition data, whole-rock major and trace element geochemistry along with whole-rock Sr-Nd isotopes and PGEs in order to constrain the evolution of the Panzhihua parent magma en route from source to chamber and the formation of Fe-Ti oxide ore layers. Furthermore an initial pilot study using O-isotope data is conducted on Ti-magnetite and plagioclase separates from gabbroic vs. ore rocks. Results are coupled with detailed thermodynamic modeling using the software PELE in order to further constrain Fe-Ti oxide ore layer formation. The intrusion is characterised by extreme depletion of PGEs relative to the coeval flood basalts and picrites. High Cu/Pd and Pd/Pt imply two separate stages of S-saturated and S-undersaturated depletion of PGEs. Pd is highly compatible in sulphide and is quickly scavenged by sulphide liquids resulting in an increase in Cu/Pd of the residual liquid. Furthermore decoupling of Pd and Pt can be achieved by either late stage hydrothermal alteration or through S-undersaturated stage of PGE depletion where Pt is scavenged by Pt-rich alloys or oxide minerals. I show that the latter is more likely. Fractionation modeling suggests that the Panzhihua parent magma formed at depth from original picritic magma. This is consistent with several other recent studies on other layered intrusions of the ELIP. Sr-Nd isotopic ratios indicate very little crustal contamination has occurred en route to the current chamber. Sr and Nd concentrations of footwall rocks are too low to produce any significant change in initial Sr and Nd isotopic ratios of the intruding basaltic magmas, indicating that crustal contamination will not be indicated by Sr-Nd isotopic ratios. Gradational change in the Sr-Nd isotope ratios across the MGZ provides strong evidence for formation in an open system by multiple replenishments of progressively less contaminated magmas from depth. Contamination is difficult to constrain but must be occurring prior to emplacement at the current level (low Sr and Nd contents of footwall). A gradational upward decrease in highly incompatible element across the MGZ can then be explained by continuous magma flow, which effectively removes the evolved intercumulus liquids from the growing cumulate pile at the base of the chamber. The initial stages of formation of the Panzhihua intrusion are interpreted to result from prolonged low volume pulses of magma into a slowly opening chamber. The timing of Fe-Ti oxide crystallisation is fundamental in the understanding of the petrogenesis of ore layers. Distinct geochemical variation in whole-rock Fe2O3/TiO2 and Zr/Nb indicates that Timagnetite is the dominant oxide within the lower ± 270 m of the intrusion whereas above this level both Ti-magnetite and ilmenite are present as cumulus phases. This is interpreted to indicate a variation in the fO2 where the lower intrusion crystallises at higher fO2 relative to that above this level. Silicates within the ore layers, in particular plagioclase, are highly embayed and resorped where in contact with Fe-Ti oxides. This characteristic of the silicate grains implies early crystallisation prior to Fe-Ti oxides with subsequent disequilibrium conditions resulting in resorption. Furthermore distinct reaction rims of kaersutite amphibole, Fo-enriched olivine, An-enriched plagioclase and pleonaste are observed. The abundance of amphibole suggests H2O involvement in this reaction and consumption of silicates. A model for parent magma crystallisation at various H2O contents indicates that plagioclase crystallisation temperature is very sensitive to H2O content of the parent magma. Plagioclase crystallises early for “dry” compositions but significantly later for “wet” compositions. Fe-Ti oxide ore layers are generally well layered, contain gabbroic xenoliths and are observed raversing/cross-cutting the cumulate stratigraphy. I present here a new model for ore layer formation in order to account for these distinct features of the ore layers. A model invoking multiple replenishments of magma with variable oxide microphenocryst content, H2O content and volume is proposed. Magma evolving in the plumbing system and fed to the Panzhihua chamber is variably enriched in H2O, which results in significantly different crystallisation paths. High H2O magmas (> 2 wt %) crystallise Fe-Ti oxides early whereas low H2O magmas (< 1 wt %) crystallise oxides late. Early pulses of H2O-poor magma crystallise a sequence of plag+cpx+Fe-Ti oxide (±ol). Later pulses of H2Orich magma subsequently intrude the partially crystallised cumulate sequence incorporating and consuming previously crystallised silicates with subsequent early crystallisation of Ti-magnetite and formation of ore layers. H2O-rich magmas likely have suspended Ti-magnetite microphenocrysts as well, which crystallise at depth in the plumbing system. This model can account for the various characteristic features of the Fe-Ti oxide ore layers at the Panzhihua intrusion as well as other Fe-Ti oxide ore bearing intrusions in the region.
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