Epitaxial growth and characterisation of CuGaS2
- Authors: Branch, Matthew Stewart
- Date: 2006
- Subjects: Epitaxy , Chalcopyrite , Semiconductors
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10541 , http://hdl.handle.net/10948/438 , http://hdl.handle.net/10948/d1012893 , Epitaxy , Chalcopyrite , Semiconductors
- Description: In this work, the growth and characterisation of the chalcopyrite semiconductor CuGaS2 is presented. The purpose of this study is to gain a better understanding of the defect chemistry of this class of materials through a systematic study relating the structural and optical properties to the composition of thin films grown by metalorganic vapour phase epitaxy. Details associated with the optimisation of the growth process are presented in a format relating the changes in the composition and morphology to variations in the growth process. The structural properties of thin films grown on GaAs(001) substrates are described. A dominance of polycrystalline growth is found to occur for Cu-rich material, whereas near-stoichiometric to Ga-rich material is typified by epitaxial growth. Secondary phases are identified by X-ray diffractometry and Raman spectroscopy for severely non-stoichiometric material. In some cases, the formation of the cubic zincblende and CuPt polytype of CuGaS2 are identified by transmission electron microscopy. It will be shown that changes in the Cu/Ga ratio of the solid strongly influence the photoluminescence response of the layers. Weak excitonic luminescence is observed for both slightly Ga-rich and Cu-rich material. Near stoichiometric layers exhibit luminescence centered at ~2.4 eV. Cu-rich layers are dominated by a line occurring at ~2.1 eV, whereas a different line at ~2.25 eV dominates for Ga-rich layers. A clear picture emerges of the radiative mechanisms dominating for Cu-rich and Ga-rich layers.
- Full Text:
- Date Issued: 2006
- Authors: Branch, Matthew Stewart
- Date: 2006
- Subjects: Epitaxy , Chalcopyrite , Semiconductors
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10541 , http://hdl.handle.net/10948/438 , http://hdl.handle.net/10948/d1012893 , Epitaxy , Chalcopyrite , Semiconductors
- Description: In this work, the growth and characterisation of the chalcopyrite semiconductor CuGaS2 is presented. The purpose of this study is to gain a better understanding of the defect chemistry of this class of materials through a systematic study relating the structural and optical properties to the composition of thin films grown by metalorganic vapour phase epitaxy. Details associated with the optimisation of the growth process are presented in a format relating the changes in the composition and morphology to variations in the growth process. The structural properties of thin films grown on GaAs(001) substrates are described. A dominance of polycrystalline growth is found to occur for Cu-rich material, whereas near-stoichiometric to Ga-rich material is typified by epitaxial growth. Secondary phases are identified by X-ray diffractometry and Raman spectroscopy for severely non-stoichiometric material. In some cases, the formation of the cubic zincblende and CuPt polytype of CuGaS2 are identified by transmission electron microscopy. It will be shown that changes in the Cu/Ga ratio of the solid strongly influence the photoluminescence response of the layers. Weak excitonic luminescence is observed for both slightly Ga-rich and Cu-rich material. Near stoichiometric layers exhibit luminescence centered at ~2.4 eV. Cu-rich layers are dominated by a line occurring at ~2.1 eV, whereas a different line at ~2.25 eV dominates for Ga-rich layers. A clear picture emerges of the radiative mechanisms dominating for Cu-rich and Ga-rich layers.
- Full Text:
- Date Issued: 2006
A pilot study of the use of groupwork in biology education at the Griffiths Mxenge College of Education : a research project ; Towards an effective implementation of assessment of biology practical work under ʺcurriculum 2005ʺ
- Authors: Kwayisi, Frederick Ntow
- Date: 1999
- Subjects: Biology -- Study and teaching -- South Africa Group work in education Biology -- Curricula Curriculum change -- South Africa Curriculum planning -- South Africa Competency-based education -- South Africa Inclusive education -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1705 , http://hdl.handle.net/10962/d1003588
- Description: A pilot study of the use of groupwork in biology education at the Griffiths Mxenge College of Education: The Government of National Unity in 1994 introduced a new educational policy for the country. This represented a shift in paradigm from a transmission mode of teaching and learning to learner-centered education. The shift marks a transformation from a contentbased curriculum to an outcomes based education (aBE). aBE, which is underpinned by Constructivism and Social Constructivism advocates for the use of groupwork as a strategy for achieving the outcomes envisaged in our learners. The challenge facing teachers and educators is how to implement outcomes based education. The intention of this research is therefore to serve as a pilot project to find out about how groupwork may be used in teaching. It looks at types of groups, considerations a teacher should have in forming groups, dynamics which come into play during teaching and gives suggestions as to how groupwork problems may be solved. Others issued are also raised which were not fully covered in the research. It is the hope of the researcher that the project would be a basis for further research on the use of group work in teaching under outcomes based education. Towards an effective implementation of assessment of biology practical work under "curriculum 2005" Transformation taking place in education in the Republic of South Africa has implications for assessment. It involves a move away from the transmission mode of teaching and learning, to a learner-centered education with the attainment of outcomes. It is a move away from the summative mode of assessment to a formative mode, where assessment leads to the development of the learner and monitor and support teaching and learning. Questions arise as to what to assess, how, when to assess and by whom? This research project is an initial attempt to look at how this assessment policy may be implemented effectively in schools and colleges, using the teaching and learning of practical biology as a tool. It looks at examples of assessment methods that may be used to assess learners work, their functions and problems that may arise in the teachers attempt to transform hislher practices. Suggestions are made on factors to consider in implementing assessment practice and how problems, which may arise in assessment, may be overcome.
- Full Text:
- Date Issued: 1999
- Authors: Kwayisi, Frederick Ntow
- Date: 1999
- Subjects: Biology -- Study and teaching -- South Africa Group work in education Biology -- Curricula Curriculum change -- South Africa Curriculum planning -- South Africa Competency-based education -- South Africa Inclusive education -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1705 , http://hdl.handle.net/10962/d1003588
- Description: A pilot study of the use of groupwork in biology education at the Griffiths Mxenge College of Education: The Government of National Unity in 1994 introduced a new educational policy for the country. This represented a shift in paradigm from a transmission mode of teaching and learning to learner-centered education. The shift marks a transformation from a contentbased curriculum to an outcomes based education (aBE). aBE, which is underpinned by Constructivism and Social Constructivism advocates for the use of groupwork as a strategy for achieving the outcomes envisaged in our learners. The challenge facing teachers and educators is how to implement outcomes based education. The intention of this research is therefore to serve as a pilot project to find out about how groupwork may be used in teaching. It looks at types of groups, considerations a teacher should have in forming groups, dynamics which come into play during teaching and gives suggestions as to how groupwork problems may be solved. Others issued are also raised which were not fully covered in the research. It is the hope of the researcher that the project would be a basis for further research on the use of group work in teaching under outcomes based education. Towards an effective implementation of assessment of biology practical work under "curriculum 2005" Transformation taking place in education in the Republic of South Africa has implications for assessment. It involves a move away from the transmission mode of teaching and learning, to a learner-centered education with the attainment of outcomes. It is a move away from the summative mode of assessment to a formative mode, where assessment leads to the development of the learner and monitor and support teaching and learning. Questions arise as to what to assess, how, when to assess and by whom? This research project is an initial attempt to look at how this assessment policy may be implemented effectively in schools and colleges, using the teaching and learning of practical biology as a tool. It looks at examples of assessment methods that may be used to assess learners work, their functions and problems that may arise in the teachers attempt to transform hislher practices. Suggestions are made on factors to consider in implementing assessment practice and how problems, which may arise in assessment, may be overcome.
- Full Text:
- Date Issued: 1999
The role of microzooplankton in carbon cycling in the Southern Ocean
- Authors: Froneman, Pierre William
- Date: 1996
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21066 , http://hdl.handle.net/10962/6234
- Description: A 3-year study was carried out on the role of microzooplankton in carbon cycling in the south Atlantic and the Atlantic sector of the Southern Ocean. Microzooplankton grazing impact on phytoplankton was estimated during austral summer and winter employing the dilution technique. Carnivory by larger zooplankton on microzooplankton during summer was estimated using in vitro incubations. Microzooplankton assemblages were always dominated by protozoans comprising ciliates and dinoflagellates. In the ( 20 um chlorophyll fraction, microzooplankton grazing was sufficient to control the growth of the nano- and picophytoplankton suggesting that, where larger microphytoplankton cells dominate, micro zooplankton maintain the background concentrations of the nano- and picophytoplankton. During winter, when small nano- and picophytoplankton cells dominate total chlorophyll concentrations, the microzooplankton grazing impact on phytoplankton is dramatically increased. Microzooplankton removed on average 37% of the initial phytoplankton stock or 70% of the daily phytoplankton production. These results suggest that in winter, micro zooplankton are the main sink for phytoplankton production. Carnivory experiments conducted with selected meso- (copepods) and macro zooplankton (euphausiids and tunicates) showed that all species examined consumed micro zooplankton in the presence of substantial chlorophyll concentrations. Microzooplankton can, therefore, be regarded as trophic intermediates between bacterioplankton, small phytoplankton cells and larger zooplankton species in the Southern Ocean. The results of this investigation suggest a spatiotemporal shift in efficiency of the biological pump mediated by changes in the size composition of the phytoplankton assemblages. South of the Antarctic Polar Front (APF) large IV microphytoplankton cells dominate the summer chlorophyll biomass, suggesting that larger zooplankton grazers represent the main sink for phytoplankton production. Under these conditions, carbon flux to the interior of the ocean will be high due to diel vertical migrations by grazers and the production of large, fast sinking faecal pellets. The sedimentation of large phytoplankton cells also contributes to flux. In the permanently open waters south of the APF and throughout the Southern Ocean during winter, small phytoplankton cells dominate total chlorophyll, resulting in the microbial loop being the main sink for phytoplankton production. The close coupling between the micro zooplankton and the microbial loop dramatically reduces the transfer of organic carbon from the surface layers to depth. Carnivory by metazoans on microzooplankton may reduce the high grazing impact of micro zooplankton and, may also represent an important source of carbon flux originating from the microbial loop.
- Full Text:
- Date Issued: 1996
- Authors: Froneman, Pierre William
- Date: 1996
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21066 , http://hdl.handle.net/10962/6234
- Description: A 3-year study was carried out on the role of microzooplankton in carbon cycling in the south Atlantic and the Atlantic sector of the Southern Ocean. Microzooplankton grazing impact on phytoplankton was estimated during austral summer and winter employing the dilution technique. Carnivory by larger zooplankton on microzooplankton during summer was estimated using in vitro incubations. Microzooplankton assemblages were always dominated by protozoans comprising ciliates and dinoflagellates. In the ( 20 um chlorophyll fraction, microzooplankton grazing was sufficient to control the growth of the nano- and picophytoplankton suggesting that, where larger microphytoplankton cells dominate, micro zooplankton maintain the background concentrations of the nano- and picophytoplankton. During winter, when small nano- and picophytoplankton cells dominate total chlorophyll concentrations, the microzooplankton grazing impact on phytoplankton is dramatically increased. Microzooplankton removed on average 37% of the initial phytoplankton stock or 70% of the daily phytoplankton production. These results suggest that in winter, micro zooplankton are the main sink for phytoplankton production. Carnivory experiments conducted with selected meso- (copepods) and macro zooplankton (euphausiids and tunicates) showed that all species examined consumed micro zooplankton in the presence of substantial chlorophyll concentrations. Microzooplankton can, therefore, be regarded as trophic intermediates between bacterioplankton, small phytoplankton cells and larger zooplankton species in the Southern Ocean. The results of this investigation suggest a spatiotemporal shift in efficiency of the biological pump mediated by changes in the size composition of the phytoplankton assemblages. South of the Antarctic Polar Front (APF) large IV microphytoplankton cells dominate the summer chlorophyll biomass, suggesting that larger zooplankton grazers represent the main sink for phytoplankton production. Under these conditions, carbon flux to the interior of the ocean will be high due to diel vertical migrations by grazers and the production of large, fast sinking faecal pellets. The sedimentation of large phytoplankton cells also contributes to flux. In the permanently open waters south of the APF and throughout the Southern Ocean during winter, small phytoplankton cells dominate total chlorophyll, resulting in the microbial loop being the main sink for phytoplankton production. The close coupling between the micro zooplankton and the microbial loop dramatically reduces the transfer of organic carbon from the surface layers to depth. Carnivory by metazoans on microzooplankton may reduce the high grazing impact of micro zooplankton and, may also represent an important source of carbon flux originating from the microbial loop.
- Full Text:
- Date Issued: 1996
Data reduction techniques for Very Long Baseline Interferometric spectropolarimetry
- Authors: Kemball, Athol James
- Date: 1993
- Subjects: Very long baseline interferometry Radio interferometers Data reduction -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5457 , http://hdl.handle.net/10962/d1005242
- Description: This thesis reports the results of an investigation into techniques for the calibration and imaging of spectral line polarization observations in Very Long Baseline Interferometry (VLBI). A review is given of the instrumental and propagation effects which need to be removed in the course of calibrating such obervations, with particular reference to their polarization dependence. The removal of amplitude and phase errors and the determination of the instrumental feed response is described. The polarization imaging of such data is discussed with particular reference to the case of poorly sampled cross-polarization data. The software implementation of the algorithms within the Astronomical Image Processing System (AlPS) is discussed and the specific case of spectral line polarization reduction for data observed using the MK3 VLBI system is considered in detail. VLBI observations at two separate epochs of the 1612 MHz OH masers towards the source IRC+ 10420 are reduced as part of this work. Spectral line polarization maps of the source structure are presented, including a discussion of source morphology and variability. The source is sigmficantly circularly polarized at VLBI resolution, but does not display appreciable linear polarization. A proper motion study of the circumstellar envelope is presented, which supports an ellipsoidal kinematic model with anisotropic radial outflow. Kinematic modelling of the measured proper motions suggests a distance to the source of ~ 3 kpc. The cirumstellar magnetic field strength in the masing regions is determined as 1-3 mG, assuming Zeeman splitting as the polarization mechanism.
- Full Text:
- Date Issued: 1993
- Authors: Kemball, Athol James
- Date: 1993
- Subjects: Very long baseline interferometry Radio interferometers Data reduction -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5457 , http://hdl.handle.net/10962/d1005242
- Description: This thesis reports the results of an investigation into techniques for the calibration and imaging of spectral line polarization observations in Very Long Baseline Interferometry (VLBI). A review is given of the instrumental and propagation effects which need to be removed in the course of calibrating such obervations, with particular reference to their polarization dependence. The removal of amplitude and phase errors and the determination of the instrumental feed response is described. The polarization imaging of such data is discussed with particular reference to the case of poorly sampled cross-polarization data. The software implementation of the algorithms within the Astronomical Image Processing System (AlPS) is discussed and the specific case of spectral line polarization reduction for data observed using the MK3 VLBI system is considered in detail. VLBI observations at two separate epochs of the 1612 MHz OH masers towards the source IRC+ 10420 are reduced as part of this work. Spectral line polarization maps of the source structure are presented, including a discussion of source morphology and variability. The source is sigmficantly circularly polarized at VLBI resolution, but does not display appreciable linear polarization. A proper motion study of the circumstellar envelope is presented, which supports an ellipsoidal kinematic model with anisotropic radial outflow. Kinematic modelling of the measured proper motions suggests a distance to the source of ~ 3 kpc. The cirumstellar magnetic field strength in the masing regions is determined as 1-3 mG, assuming Zeeman splitting as the polarization mechanism.
- Full Text:
- Date Issued: 1993
Selecting educational computer software and evaluating its use, with special reference to biology education
- Authors: Beyers, Ronald Noel
- Date: 1992
- Subjects: Biology -- Study and teaching -- Computer programs Education -- Data processing Biology -- Computer-assisted instruction
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1764 , http://hdl.handle.net/10962/d1003649
- Description: In the field of Biology there is a reasonable amount of software available for educational use but in the researcher's experience there are few teachers who take the computer into the classroom/laboratory, Teachers will make use of video machines and tape recorders quite happily, but a computer is a piece of apparatus which they are not prepared to use in the classroom/laboratory. This thesis is an attempt to devise an educational package, consisting of a Selection Form and an Evaluation Form, which can be used by teachers to select and evaluate educational software in the field of Biology. The forms were designed specifically for teachers to use in preparation of a computer lesson. The evaluation package also provides the teacher with a means of identifying whether the lesson has achieved its objectives or not. The teacher may also be provided with feedback about the lesson. The data is gathered by means of a questionnaire which the pupils complete. It would appear that teachers are uncertain as regards the purchase of software for their subject from the many catalogues that are available. The evaluation package implemented in this research can be regarded as the beginnings of a data base for the accumulation of information to assist teachers with details on which software to select. Evidence is provided in this thesis for the practical application of the Selection and Evaluation Forms, using Biology software.
- Full Text:
- Date Issued: 1992
- Authors: Beyers, Ronald Noel
- Date: 1992
- Subjects: Biology -- Study and teaching -- Computer programs Education -- Data processing Biology -- Computer-assisted instruction
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1764 , http://hdl.handle.net/10962/d1003649
- Description: In the field of Biology there is a reasonable amount of software available for educational use but in the researcher's experience there are few teachers who take the computer into the classroom/laboratory, Teachers will make use of video machines and tape recorders quite happily, but a computer is a piece of apparatus which they are not prepared to use in the classroom/laboratory. This thesis is an attempt to devise an educational package, consisting of a Selection Form and an Evaluation Form, which can be used by teachers to select and evaluate educational software in the field of Biology. The forms were designed specifically for teachers to use in preparation of a computer lesson. The evaluation package also provides the teacher with a means of identifying whether the lesson has achieved its objectives or not. The teacher may also be provided with feedback about the lesson. The data is gathered by means of a questionnaire which the pupils complete. It would appear that teachers are uncertain as regards the purchase of software for their subject from the many catalogues that are available. The evaluation package implemented in this research can be regarded as the beginnings of a data base for the accumulation of information to assist teachers with details on which software to select. Evidence is provided in this thesis for the practical application of the Selection and Evaluation Forms, using Biology software.
- Full Text:
- Date Issued: 1992
An investigation into some learning and teaching problems of biology in Transkei senior secondary schools
- Authors: Matoti, Sheila Nokuthula
- Date: 1990
- Subjects: Education, Secondary Biology -- Study and teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1349 , http://hdl.handle.net/10962/d1001415
- Description: The aim of this study was to investigate some learning and teaching problems of biology in Transkei Senior Secondary schools. The research focussed mainly on Biochemistry. Biochemistry was treated in the context of biology as a whole to show its relevance to other sections of the syllabus. Questionnaires were administered to standard 10 pupils in 15 senior secondary schools selected randomly from the Central Region of Transkei. Further information on pupils' understanding of concepts taught in Biochemistry , was gained through use of concept tests and concept maps. Interviews were conducted with standard 9 and 10 biology teachers, Subject committee members, Examiners, Subject advisers, Lecturers from the University of Transkei and the Transkei Teachers' In-service College and pupils. Data obtained through the use of those research methods was analysed and discussed. Concept mapping as a teaching strategy was introduced to some standard 9 and 10 teachers who attended courses (biology) at The Transkei Teachers ' In-service College. Some suggestions and recommendations for the learning and teaching of biology were then made
- Full Text:
- Date Issued: 1990
- Authors: Matoti, Sheila Nokuthula
- Date: 1990
- Subjects: Education, Secondary Biology -- Study and teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1349 , http://hdl.handle.net/10962/d1001415
- Description: The aim of this study was to investigate some learning and teaching problems of biology in Transkei Senior Secondary schools. The research focussed mainly on Biochemistry. Biochemistry was treated in the context of biology as a whole to show its relevance to other sections of the syllabus. Questionnaires were administered to standard 10 pupils in 15 senior secondary schools selected randomly from the Central Region of Transkei. Further information on pupils' understanding of concepts taught in Biochemistry , was gained through use of concept tests and concept maps. Interviews were conducted with standard 9 and 10 biology teachers, Subject committee members, Examiners, Subject advisers, Lecturers from the University of Transkei and the Transkei Teachers' In-service College and pupils. Data obtained through the use of those research methods was analysed and discussed. Concept mapping as a teaching strategy was introduced to some standard 9 and 10 teachers who attended courses (biology) at The Transkei Teachers ' In-service College. Some suggestions and recommendations for the learning and teaching of biology were then made
- Full Text:
- Date Issued: 1990
A preliminary examination of teacher development in farm schools through an illuminative evaluation of a teacher development course implemented by the 1820 Foundation Farm School Project
- Authors: Gale, Frances
- Date: 1989
- Subjects: Rural schools -- South Africa -- Eastern Cape Teachers -- Training of -- South Africa -- Eastern Cape 1820 Foundation. Inset Farm School Project Rural schools
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1712 , http://hdl.handle.net/10962/d1003595
- Description: The 1820 Foundation INSET Farm School Project is described in order to set the context in which this illuminative evaluation of a Teacher Development course took place. The concepts of training, education and development are discussed and it is suggested that the term 'education' encompasses a training-development continuum. The design and implementation of the Teacher Development course, which attempts to promote both personal and professional development, are presented, and the facilitator discusses i) her attempt to encourage teacher control of the course and, ii) the factors which mitigate against teacher control. The decision to use the illuminative evaluation method is placed in the context of interpretive research methodologies, and the methods of data collection are discussed. A wide range of data sources is used, but primary importance is attached to i) a questionnaire administered to the five teachers involved and ii) a group interview and individual interviews with the teachers. Factors which emerge in the illumination of the data indicate that teacher control of development courses in farm schools in the Eastern Cape is problematic, that the teachers' preference is for professional development, and that development seems to take place through implementation of training strategies.
- Full Text:
- Date Issued: 1989
- Authors: Gale, Frances
- Date: 1989
- Subjects: Rural schools -- South Africa -- Eastern Cape Teachers -- Training of -- South Africa -- Eastern Cape 1820 Foundation. Inset Farm School Project Rural schools
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1712 , http://hdl.handle.net/10962/d1003595
- Description: The 1820 Foundation INSET Farm School Project is described in order to set the context in which this illuminative evaluation of a Teacher Development course took place. The concepts of training, education and development are discussed and it is suggested that the term 'education' encompasses a training-development continuum. The design and implementation of the Teacher Development course, which attempts to promote both personal and professional development, are presented, and the facilitator discusses i) her attempt to encourage teacher control of the course and, ii) the factors which mitigate against teacher control. The decision to use the illuminative evaluation method is placed in the context of interpretive research methodologies, and the methods of data collection are discussed. A wide range of data sources is used, but primary importance is attached to i) a questionnaire administered to the five teachers involved and ii) a group interview and individual interviews with the teachers. Factors which emerge in the illumination of the data indicate that teacher control of development courses in farm schools in the Eastern Cape is problematic, that the teachers' preference is for professional development, and that development seems to take place through implementation of training strategies.
- Full Text:
- Date Issued: 1989
The hydrogeology of a Karoo basalt/sandstone contact aquifer moretele II district Republic of Bophuthatswana southern Africa
- Authors: Martinelli, Giorgio Luigi
- Date: 1988
- Subjects: Basalt -- South Africa -- Bophuthatswana Sandstone -- South Africa -- Bophuthatswana Aquifers -- South Africa -- Bophuthatswana Hydrogeology -- South Africa -- Bophuthatswana
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4802 , http://hdl.handle.net/10962/d1001902
- Description: As part of a development programme in the Moretele II District, the Government of the Republic of Bophuthatswana, commissioned in 1983 the building of a dry system coal-fired power station. The lack of local surface water to cool the power station resulted in a decision to investigate the potential of the ground water resources. The resources will be required to supply an anticipated 30 year water demand. Because of the high capital investment and the importance of establishing an accurate assessement of the ground water potential there was a need for a comprehensive and detailed hydrogeological study. The specific aim of the investigation is to assess and quantify the long term reliability of the ground water resources. The very limited data for the area necessitated a particularly thorough and detailed investigation. This thesis describes the hydrogeological investigation carried out to define the ground water resource potential of this area. The main objectives of the study are to identify, recognize and evaluate the hydrogeological processes operating on this previously ill-defined Karoo aquifer. To achieve the research objectives the hydrogeological investigation was formulated to make use of various traditional geological, hydrogeological, geophysical and hydrochemical techniques in a logical framework. More specifically, the work involved a hydrocensus, a geophysical survey, the drilling of exploratory boreholes, aquifer tests to determine the intrinsic hydraulic parameters, water level measurements and the collection and analysis of water samples. The combined results of these various techniques provided data to quantify, evaluate and then propose management strategies for the identified resources. The study provided an understanding of the local hydrogeological conditions and has allowed for a conceptual model of the aquifer system to be derived
- Full Text:
- Date Issued: 1988
- Authors: Martinelli, Giorgio Luigi
- Date: 1988
- Subjects: Basalt -- South Africa -- Bophuthatswana Sandstone -- South Africa -- Bophuthatswana Aquifers -- South Africa -- Bophuthatswana Hydrogeology -- South Africa -- Bophuthatswana
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4802 , http://hdl.handle.net/10962/d1001902
- Description: As part of a development programme in the Moretele II District, the Government of the Republic of Bophuthatswana, commissioned in 1983 the building of a dry system coal-fired power station. The lack of local surface water to cool the power station resulted in a decision to investigate the potential of the ground water resources. The resources will be required to supply an anticipated 30 year water demand. Because of the high capital investment and the importance of establishing an accurate assessement of the ground water potential there was a need for a comprehensive and detailed hydrogeological study. The specific aim of the investigation is to assess and quantify the long term reliability of the ground water resources. The very limited data for the area necessitated a particularly thorough and detailed investigation. This thesis describes the hydrogeological investigation carried out to define the ground water resource potential of this area. The main objectives of the study are to identify, recognize and evaluate the hydrogeological processes operating on this previously ill-defined Karoo aquifer. To achieve the research objectives the hydrogeological investigation was formulated to make use of various traditional geological, hydrogeological, geophysical and hydrochemical techniques in a logical framework. More specifically, the work involved a hydrocensus, a geophysical survey, the drilling of exploratory boreholes, aquifer tests to determine the intrinsic hydraulic parameters, water level measurements and the collection and analysis of water samples. The combined results of these various techniques provided data to quantify, evaluate and then propose management strategies for the identified resources. The study provided an understanding of the local hydrogeological conditions and has allowed for a conceptual model of the aquifer system to be derived
- Full Text:
- Date Issued: 1988
The contribution of William Gurnall (1616-1679) to the puritan concept of spiritual combat, with special emphasis on the role of faith
- Van Zyl, Frederick William James
- Authors: Van Zyl, Frederick William James
- Date: 1986
- Subjects: Gurnall, William, 1617-1679 , Puritans , Faith , Spiritual life -- Christianity -- History of doctrines
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:1223 , http://hdl.handle.net/10962/d1003916
- Description: The Central figure in this thesis is William Gurnall M.A. (Cambridge) who lived from 1616 to 1679. He was the Rector of the Lavenham Parish church for 35 years, 1644/45-1679. He was one of the few Puritans who remained in the Established Church after the 1662 Act of Uniformity had been promulgated. His 'The Christian in Complete Armour' is one of the greatest practical-pastoral works to come from the pen of any Puritan. It is firmly based on Calvinistic theological principles. While holding common beliefs in many areas, Gurnall nevertheless was at odds with his fellow Puritans over certain crucial issues that directly affected his attitude to the Puritan revolution. His analysis of the person, being, nature, wiles, strategies and weapons of the Christian's great enemy and description of the Christian's resources such as the role of the shield of faith in its multiple uses, which constitute an important contribution to pastoral theory and practice are shown to arise out of Gurnall's theological stance, his own personal history, the history of East Anglia and of Lavenham in particular; his reflections on the 'Days of Great Confusions' and his deep concern for the breakdown in orderly society and the decline of genuine piety in the church. Basically we will concentrate on three issues: First. The real nature and locus of the Christian's spiritual warfare. Second. -- The means used for his investigation, namely, an examination of the person, power, methods and wiles of the Christian's great enemy and the vital role of the shield of faith. -- Third. His conclusions.
- Full Text:
- Date Issued: 1986
- Authors: Van Zyl, Frederick William James
- Date: 1986
- Subjects: Gurnall, William, 1617-1679 , Puritans , Faith , Spiritual life -- Christianity -- History of doctrines
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:1223 , http://hdl.handle.net/10962/d1003916
- Description: The Central figure in this thesis is William Gurnall M.A. (Cambridge) who lived from 1616 to 1679. He was the Rector of the Lavenham Parish church for 35 years, 1644/45-1679. He was one of the few Puritans who remained in the Established Church after the 1662 Act of Uniformity had been promulgated. His 'The Christian in Complete Armour' is one of the greatest practical-pastoral works to come from the pen of any Puritan. It is firmly based on Calvinistic theological principles. While holding common beliefs in many areas, Gurnall nevertheless was at odds with his fellow Puritans over certain crucial issues that directly affected his attitude to the Puritan revolution. His analysis of the person, being, nature, wiles, strategies and weapons of the Christian's great enemy and description of the Christian's resources such as the role of the shield of faith in its multiple uses, which constitute an important contribution to pastoral theory and practice are shown to arise out of Gurnall's theological stance, his own personal history, the history of East Anglia and of Lavenham in particular; his reflections on the 'Days of Great Confusions' and his deep concern for the breakdown in orderly society and the decline of genuine piety in the church. Basically we will concentrate on three issues: First. The real nature and locus of the Christian's spiritual warfare. Second. -- The means used for his investigation, namely, an examination of the person, power, methods and wiles of the Christian's great enemy and the vital role of the shield of faith. -- Third. His conclusions.
- Full Text:
- Date Issued: 1986
An ecological study of the ixodid tick rhipicephalus glabroscutatum (Du Toit, 1941)
- Macivor, Keith Malcolm de Falloux
- Authors: Macivor, Keith Malcolm de Falloux
- Date: 1983
- Subjects: Ticks -- Control -- South Africa -- Eastern Cape Parasites -- South Africa -- Eastern Cape Rhipicephalus -- South Africa -- Eastern Cape Angora goat -- South Africa -- Eastern Cape Larvae -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5602 , http://hdl.handle.net/10962/d1002052
- Description: An intensive study was conducted on the free-living larvae and parasitic life stages of R.glabroscutatum on Angora and Boer goats in the Uitenhage district. Free-living larvae exhibited periods of maximum relative abundance during months of generally lower rainfall, from the end of autumn to the beginning of spring. Relative larval abundance in open and gully sites was low while larvae were rarely found in bush sites. Relative abundance was higher at 20h00 than at 08h00 and 14h00. Repeated sampling in the same areas did not reduce larval numbers. Over 99% of parasitic ticks removed from Angora and Boer goats were located on the feet. The annual occurrence of a low and variable number of parasitic immatures was synchronous with the occurrence of free-living larvae. High, less variable numbers of adult ticks were removed from goat feet from September to December, the highest numbers being recorded during October and November. The occurrence of a single period of parasitic adult abundance annually indicated a life cycle with 1 generation per anum. There were higher numbers of adult ticks on the feet of the Angora goats than on the Boer goats. Adult numbers were higher on the hind feet of both breeds of goats than on the front feet. R.glabroscutatum adults seem to be implicated in the aetiology of foot abscesses since more infections were observed in Angora goats than in Boer goats and on the hind feet rather than the front feet within both goat groups. In addition R.glabroscutatum adults attached at interdigital sites where abscesses also originated and reached highest numbers in October and November when abscesses were most frequently observed. A review of distribution and host records indicated that R.glabroscutatum was limited in its distribution to the eastern Cape Province, being primarily located in South Africa's major mohair producing areas. R.glabroscutatum was classed an obligative xerophile on the basis of its recorded occurrence in non coastal areas with a low annual rainfall and Karoo and Karroid Bush vegetation. Host records for R.glabroscutatum included 10 species of wild ungulate, sheep, goats and cattle. The common site of occurrence on small stock and on small to medium sized wild animals appeared to be the legs and feet.
- Full Text:
- Date Issued: 1983
- Authors: Macivor, Keith Malcolm de Falloux
- Date: 1983
- Subjects: Ticks -- Control -- South Africa -- Eastern Cape Parasites -- South Africa -- Eastern Cape Rhipicephalus -- South Africa -- Eastern Cape Angora goat -- South Africa -- Eastern Cape Larvae -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5602 , http://hdl.handle.net/10962/d1002052
- Description: An intensive study was conducted on the free-living larvae and parasitic life stages of R.glabroscutatum on Angora and Boer goats in the Uitenhage district. Free-living larvae exhibited periods of maximum relative abundance during months of generally lower rainfall, from the end of autumn to the beginning of spring. Relative larval abundance in open and gully sites was low while larvae were rarely found in bush sites. Relative abundance was higher at 20h00 than at 08h00 and 14h00. Repeated sampling in the same areas did not reduce larval numbers. Over 99% of parasitic ticks removed from Angora and Boer goats were located on the feet. The annual occurrence of a low and variable number of parasitic immatures was synchronous with the occurrence of free-living larvae. High, less variable numbers of adult ticks were removed from goat feet from September to December, the highest numbers being recorded during October and November. The occurrence of a single period of parasitic adult abundance annually indicated a life cycle with 1 generation per anum. There were higher numbers of adult ticks on the feet of the Angora goats than on the Boer goats. Adult numbers were higher on the hind feet of both breeds of goats than on the front feet. R.glabroscutatum adults seem to be implicated in the aetiology of foot abscesses since more infections were observed in Angora goats than in Boer goats and on the hind feet rather than the front feet within both goat groups. In addition R.glabroscutatum adults attached at interdigital sites where abscesses also originated and reached highest numbers in October and November when abscesses were most frequently observed. A review of distribution and host records indicated that R.glabroscutatum was limited in its distribution to the eastern Cape Province, being primarily located in South Africa's major mohair producing areas. R.glabroscutatum was classed an obligative xerophile on the basis of its recorded occurrence in non coastal areas with a low annual rainfall and Karoo and Karroid Bush vegetation. Host records for R.glabroscutatum included 10 species of wild ungulate, sheep, goats and cattle. The common site of occurrence on small stock and on small to medium sized wild animals appeared to be the legs and feet.
- Full Text:
- Date Issued: 1983
The effect of ultraviolet and gamma irradation on soluble calf-skin collagen
- Authors: Davidson, Raymond John
- Date: 1967
- Subjects: Collagen -- Hide powder Irradiation Solids -- Effect of radiation on Gamma rays -- Dose-response relationship
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4290 , http://hdl.handle.net/10962/d1003718
- Description: Initially the present study was confined to the effects of ultraviolet irradiation on acid-soluble collagen. Such a study was undertaken in order to demonstrate the critical role played by tyrosine and phenylalanine in the intermolecular interaction of the telopeptides protruding from the rigid parent collagen molecule. Since both tyrosine and phenylalanine are photosensitive, and because the collagen telopeptides are relatively rich in these aromatic amino acids, carefully controlled degradation studies involving telopeptide liberation could be made. It became increasingly apparent during the course of investigation, that a better understanding of the subunit composition of thermally denatured acid-soluble collagen was necessary if a satisfactory interpretation of the irradiation studies was to be made. A subsequent study of the subunit composition of thermally denatured acid-soluble collagen resulted in the isolation and characterisation of two major and two minor dimeric components as well as the α- and β - subunits. Three acidic telopeptides and three basic telopeptides were also isolated from acid-soluble collagen during the course of the present study. The presence of the dimeric components while related directly to the method of preparation, suggested that acid-soluble collagen was largely dimeric in nature. Such a conclusion suggested an intermolecular rather than an intraolecular relationship between neutral-salt-soluble and acid-soluble collagen. While it is currently accepted that an intramolecular relationship exists between neutral-salt-soluble and acid-soluble collagen, such a relationship does not satisfactorily explain the very different solubility characteristics displayed by these soluble collagen extracts. With this in mind, and using the study on the subunit composition of thermally denatured acid-soluble collagen as a basis for comparison, the intra and intermolecular relationship between neutral-salt-soluble and acid-soluble collagen was investigated using ultraviolet and gamma irradiation. The effects of ultraviolet and gamma irradiation on soluble collagen preparations proved very similar. Although collagen samples were irradiated in solution from an ultraviolet source; and under anhydrous conditions from a gamma source, much the same degradation mechanism resulted. The initial depolymerisation of dimeric material followed by peptide fission, yielding irradiation-resistant crystalline portions of the parent triple helix, took place in both instances. At the same time, both studies indicated no significant differences in the intra or intermolecular structures of the neutral-salt-soluble and acid-soluble preparations investigated. The dimer content of neutral-salt-soluble collagen preparations was, however, noted to be smaller. To current methods for the preparation of soluble collagens, it may be concluded that such preparations are peptideless to some degree. While the native tropocollagen monomer with its full complement of telopeptide side chains may actively undergo linear polymerisation resulting in fibre formation, the soluble collagen preparations referred to above may only aggregate in a rather random fashion.
- Full Text:
- Date Issued: 1967
- Authors: Davidson, Raymond John
- Date: 1967
- Subjects: Collagen -- Hide powder Irradiation Solids -- Effect of radiation on Gamma rays -- Dose-response relationship
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4290 , http://hdl.handle.net/10962/d1003718
- Description: Initially the present study was confined to the effects of ultraviolet irradiation on acid-soluble collagen. Such a study was undertaken in order to demonstrate the critical role played by tyrosine and phenylalanine in the intermolecular interaction of the telopeptides protruding from the rigid parent collagen molecule. Since both tyrosine and phenylalanine are photosensitive, and because the collagen telopeptides are relatively rich in these aromatic amino acids, carefully controlled degradation studies involving telopeptide liberation could be made. It became increasingly apparent during the course of investigation, that a better understanding of the subunit composition of thermally denatured acid-soluble collagen was necessary if a satisfactory interpretation of the irradiation studies was to be made. A subsequent study of the subunit composition of thermally denatured acid-soluble collagen resulted in the isolation and characterisation of two major and two minor dimeric components as well as the α- and β - subunits. Three acidic telopeptides and three basic telopeptides were also isolated from acid-soluble collagen during the course of the present study. The presence of the dimeric components while related directly to the method of preparation, suggested that acid-soluble collagen was largely dimeric in nature. Such a conclusion suggested an intermolecular rather than an intraolecular relationship between neutral-salt-soluble and acid-soluble collagen. While it is currently accepted that an intramolecular relationship exists between neutral-salt-soluble and acid-soluble collagen, such a relationship does not satisfactorily explain the very different solubility characteristics displayed by these soluble collagen extracts. With this in mind, and using the study on the subunit composition of thermally denatured acid-soluble collagen as a basis for comparison, the intra and intermolecular relationship between neutral-salt-soluble and acid-soluble collagen was investigated using ultraviolet and gamma irradiation. The effects of ultraviolet and gamma irradiation on soluble collagen preparations proved very similar. Although collagen samples were irradiated in solution from an ultraviolet source; and under anhydrous conditions from a gamma source, much the same degradation mechanism resulted. The initial depolymerisation of dimeric material followed by peptide fission, yielding irradiation-resistant crystalline portions of the parent triple helix, took place in both instances. At the same time, both studies indicated no significant differences in the intra or intermolecular structures of the neutral-salt-soluble and acid-soluble preparations investigated. The dimer content of neutral-salt-soluble collagen preparations was, however, noted to be smaller. To current methods for the preparation of soluble collagens, it may be concluded that such preparations are peptideless to some degree. While the native tropocollagen monomer with its full complement of telopeptide side chains may actively undergo linear polymerisation resulting in fibre formation, the soluble collagen preparations referred to above may only aggregate in a rather random fashion.
- Full Text:
- Date Issued: 1967
The servant of Yahweh : a critical and exegetical study of the Servant Songs in Deutero-Isaiah
- Dijkman, Jan Hendrik Leonard
- Authors: Dijkman, Jan Hendrik Leonard
- Date: 1961
- Subjects: Bible -- Criticism, interpretation, etc. , Servant songs
- Language: English
- Type: Thesis , Bachelor , BDiv
- Identifier: vital:1293 , http://hdl.handle.net/10962/d1014812
- Description: For more than two thousand years the question of tbe identity of the Servant of Yahweh in Is. 40 - 55, and especially in the so-called "Servant Songs", has exercised the minds of students of the Old Testament. The first answer which we may trace with any certainty is that of the translator of this particular section in the Septuagint, who adds the words "Jacob" and "Israel" to the text. This is closely followed in the New Testament by the answer which Philip gave to the Ethiopian eunuch's query, "Of whom speaketh the prophet this ? of himself, or of some other ?" ( Acts 8:34f,). These two answers are typical of the two possible extremes in solving the problem. The first sees the Servant as a collective entity, the people Israel, while the second sees him as an individual figure, namely, Jesus Christ. The second answer explains why the interpretation of the Servant figure has been such a live issue throughout the entire history of Christendom. In it Christians have seen a prophecy of Jesus Christ - and more particularly in the suffering of the Servant, a prophecy of the facts which form the basis of the Christian Salvation, the death and resurrection of Jesus. Until the close of the eighteenth century, the generally accepted interpretation of the figure of the Suffering Servant among Christians was to identify him completely with Christ. With the development of the scientific study of the Old Testament during the last two centuries, every generation has raised the question afresh and sought to answer it. There is hardly an Old Testament scholar who has not laboured over it, and many have published their attempts at a solution. Hence the literature on the subject is enormous. In the present study no attempt has been made to give an exhaustive survey of all the interpretations of the Servant figure, but the text of the Servant Songs has been examined before an interpretation of the Servant figure was attempted. It is to be hoped that the final interpretation here given will reflect the thought of the prophet rather than that of the interpreter.
- Full Text:
- Date Issued: 1961
- Authors: Dijkman, Jan Hendrik Leonard
- Date: 1961
- Subjects: Bible -- Criticism, interpretation, etc. , Servant songs
- Language: English
- Type: Thesis , Bachelor , BDiv
- Identifier: vital:1293 , http://hdl.handle.net/10962/d1014812
- Description: For more than two thousand years the question of tbe identity of the Servant of Yahweh in Is. 40 - 55, and especially in the so-called "Servant Songs", has exercised the minds of students of the Old Testament. The first answer which we may trace with any certainty is that of the translator of this particular section in the Septuagint, who adds the words "Jacob" and "Israel" to the text. This is closely followed in the New Testament by the answer which Philip gave to the Ethiopian eunuch's query, "Of whom speaketh the prophet this ? of himself, or of some other ?" ( Acts 8:34f,). These two answers are typical of the two possible extremes in solving the problem. The first sees the Servant as a collective entity, the people Israel, while the second sees him as an individual figure, namely, Jesus Christ. The second answer explains why the interpretation of the Servant figure has been such a live issue throughout the entire history of Christendom. In it Christians have seen a prophecy of Jesus Christ - and more particularly in the suffering of the Servant, a prophecy of the facts which form the basis of the Christian Salvation, the death and resurrection of Jesus. Until the close of the eighteenth century, the generally accepted interpretation of the figure of the Suffering Servant among Christians was to identify him completely with Christ. With the development of the scientific study of the Old Testament during the last two centuries, every generation has raised the question afresh and sought to answer it. There is hardly an Old Testament scholar who has not laboured over it, and many have published their attempts at a solution. Hence the literature on the subject is enormous. In the present study no attempt has been made to give an exhaustive survey of all the interpretations of the Servant figure, but the text of the Servant Songs has been examined before an interpretation of the Servant figure was attempted. It is to be hoped that the final interpretation here given will reflect the thought of the prophet rather than that of the interpreter.
- Full Text:
- Date Issued: 1961
Studies in the comparative anatomy and systematic importance of the hexapod tentorium
- Authors: Hudson, Gerda Bland
- Date: 1954
- Subjects: Insects -- Anatomy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5858 , http://hdl.handle.net/10962/d1012457
- Description: During a study of the morphology of the orthopteroid Hexapoda between the years 1939-1941, it appeareded to the writer that further investigation into the structure of the insect tentorium was necessary. The early entomologists laid the foundation or our knowledge or the tentorium but during the latter half of the last century little was added in this particulart field. Comstock and Kochi (1902), as far as the writer is aware are the only workers who have published a paper devoted entirely to the skeleton of the bead of insects, and they did much to clarify both nomenclature and existing knowledge of this structure at that time. Berlese (1909) described a typical tentorlum as observed in orthopteroid Hexapoda and then considered the variations of the tentorium which occur in other groups of insects. Some confusion then appears to have arisen amongst workers, over the origin of the dorsal arms which were erroneously considered by some to be cuticular invaginations and not secondary outgrowths of the anterior tentorial arms. Certain morphologists amongst them, Hoke (1924) Denis (1928), Snodgrass (1928, 1935), Hansen (1930), Walker (1933) Imms (1934), and Symmons (1952), have done much towards improving our knowledge of the tentorium, but all too frequently workers offer brief and inadequate descriptions of this structure in otherwise comprehensive investigations of the insect head. Themain objects in this study are threefold, vlz. (1) The claification of nomenclature (2) The examination and the interpretation ot the tentorium in certain groups of insects. (3) The deliberation as to whether the tentorium is of phylogenetic significance, and thus of use in assessing various schemes of insect classification which have been presented. Introduction, p. 1-2.
- Full Text:
- Date Issued: 1954
- Authors: Hudson, Gerda Bland
- Date: 1954
- Subjects: Insects -- Anatomy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5858 , http://hdl.handle.net/10962/d1012457
- Description: During a study of the morphology of the orthopteroid Hexapoda between the years 1939-1941, it appeareded to the writer that further investigation into the structure of the insect tentorium was necessary. The early entomologists laid the foundation or our knowledge or the tentorium but during the latter half of the last century little was added in this particulart field. Comstock and Kochi (1902), as far as the writer is aware are the only workers who have published a paper devoted entirely to the skeleton of the bead of insects, and they did much to clarify both nomenclature and existing knowledge of this structure at that time. Berlese (1909) described a typical tentorlum as observed in orthopteroid Hexapoda and then considered the variations of the tentorium which occur in other groups of insects. Some confusion then appears to have arisen amongst workers, over the origin of the dorsal arms which were erroneously considered by some to be cuticular invaginations and not secondary outgrowths of the anterior tentorial arms. Certain morphologists amongst them, Hoke (1924) Denis (1928), Snodgrass (1928, 1935), Hansen (1930), Walker (1933) Imms (1934), and Symmons (1952), have done much towards improving our knowledge of the tentorium, but all too frequently workers offer brief and inadequate descriptions of this structure in otherwise comprehensive investigations of the insect head. Themain objects in this study are threefold, vlz. (1) The claification of nomenclature (2) The examination and the interpretation ot the tentorium in certain groups of insects. (3) The deliberation as to whether the tentorium is of phylogenetic significance, and thus of use in assessing various schemes of insect classification which have been presented. Introduction, p. 1-2.
- Full Text:
- Date Issued: 1954