A distributed approach to surround sound production
- Authors: Smith, Adrian Wilfrid
- Date: 1999
- Subjects: Surround-sound systems , Computer sound processing , Music -- Data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4602 , http://hdl.handle.net/10962/d1004855 , Surround-sound systems , Computer sound processing , Music -- Data processing
- Description: The requirement for multi-channel surround sound in audio production applications is growing rapidly. Audio processing in these applications can be costly, particularly in multi-channel systems. A distributed approach is proposed for the development of a realtime spatialization system for surround sound music production, using Ambisonic surround sound methods. The latency in the system is analyzed, with a focus on the audio processing and network delays, in order to ascertain the feasibility of an enhanced, distributed real-time spatialization system.
- Full Text:
- Date Issued: 1999
- Authors: Smith, Adrian Wilfrid
- Date: 1999
- Subjects: Surround-sound systems , Computer sound processing , Music -- Data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4602 , http://hdl.handle.net/10962/d1004855 , Surround-sound systems , Computer sound processing , Music -- Data processing
- Description: The requirement for multi-channel surround sound in audio production applications is growing rapidly. Audio processing in these applications can be costly, particularly in multi-channel systems. A distributed approach is proposed for the development of a realtime spatialization system for surround sound music production, using Ambisonic surround sound methods. The latency in the system is analyzed, with a focus on the audio processing and network delays, in order to ascertain the feasibility of an enhanced, distributed real-time spatialization system.
- Full Text:
- Date Issued: 1999
A review of Southern African kimberlites and exploration techniques
- Authors: Venter, Louis Johannes
- Date: 1999 , 2013-10-04
- Subjects: Kimberlite -- Africa, Southern , Diamonds -- Africa, Southern , Prospecting -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5033 , http://hdl.handle.net/10962/d1007278 , Kimberlite -- Africa, Southern , Diamonds -- Africa, Southern , Prospecting -- South Africa
- Description: The dissertation reviews the present knowledge regarding diamonds, from its formation in the lithospheric upper mantle at depths between 150 and 300 km, to its final valuation in terms of US$/carat by diamantaires in London, Antwerp, Tel Aviv and New York. The dissertation is divided into two complimentary sections. Section one focuses on the formation, emplacement, occurrence and characteristics of kimberlites and, when present, their associated trace amounts of diamonds. The section follows a logical sequence from the regional tectonic-, local structrual- and geodynamic controls on kimberlite formation and emplacement to the characteristics of individual kimberlite morphology, mineralogy, petrography and geochemistry. Finally, the environment or diamond formation, resorption and the characteristics that have led to the marketability of diamonds are discussed. Section two reviews the current exploration techniques used in locating diamondiferous kimberliies and the subsequent economic evaluation of these kimberlites. A brief history of known Southern African kimberlite occurrences, grades, tonnages, tectonic settings, ages and regional structural controls is given. The prospective countries mentioned are Angola, Botswana, Lesotho, South Africa, Swaziland, Tanzania and Zimbabwe. Exploration techniques considered are ; the application of a landscape analysis and investigation of the surface processes active in a given area, indicator mineral sampling (with reference to their mineralogy and exploration significance), remote sensing techniques (subdivided into satellite imagery and aerial photography), geophysical techniques (including the magnetic-, gravity-, electrical-, radiometric- and seismic methods as well as heat flow models), geochemical techniques, petrographic- and electron beam techniques as well as geobotanical- and geobiological techniques. Finally, a brief summary of current evaluation techniques employed on diamondiferous kimberlite deposits is presented. The review covers kimberlite sampling methods, sample processing, diamond grade distributions (with reference to the experimental variogram model, statistical methods used in grade distribution calculations as well as block definition and local grade estimation). Stone size distributions, including microdiamond counts and value estimation, are also discussed. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1999
- Authors: Venter, Louis Johannes
- Date: 1999 , 2013-10-04
- Subjects: Kimberlite -- Africa, Southern , Diamonds -- Africa, Southern , Prospecting -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5033 , http://hdl.handle.net/10962/d1007278 , Kimberlite -- Africa, Southern , Diamonds -- Africa, Southern , Prospecting -- South Africa
- Description: The dissertation reviews the present knowledge regarding diamonds, from its formation in the lithospheric upper mantle at depths between 150 and 300 km, to its final valuation in terms of US$/carat by diamantaires in London, Antwerp, Tel Aviv and New York. The dissertation is divided into two complimentary sections. Section one focuses on the formation, emplacement, occurrence and characteristics of kimberlites and, when present, their associated trace amounts of diamonds. The section follows a logical sequence from the regional tectonic-, local structrual- and geodynamic controls on kimberlite formation and emplacement to the characteristics of individual kimberlite morphology, mineralogy, petrography and geochemistry. Finally, the environment or diamond formation, resorption and the characteristics that have led to the marketability of diamonds are discussed. Section two reviews the current exploration techniques used in locating diamondiferous kimberliies and the subsequent economic evaluation of these kimberlites. A brief history of known Southern African kimberlite occurrences, grades, tonnages, tectonic settings, ages and regional structural controls is given. The prospective countries mentioned are Angola, Botswana, Lesotho, South Africa, Swaziland, Tanzania and Zimbabwe. Exploration techniques considered are ; the application of a landscape analysis and investigation of the surface processes active in a given area, indicator mineral sampling (with reference to their mineralogy and exploration significance), remote sensing techniques (subdivided into satellite imagery and aerial photography), geophysical techniques (including the magnetic-, gravity-, electrical-, radiometric- and seismic methods as well as heat flow models), geochemical techniques, petrographic- and electron beam techniques as well as geobotanical- and geobiological techniques. Finally, a brief summary of current evaluation techniques employed on diamondiferous kimberlite deposits is presented. The review covers kimberlite sampling methods, sample processing, diamond grade distributions (with reference to the experimental variogram model, statistical methods used in grade distribution calculations as well as block definition and local grade estimation). Stone size distributions, including microdiamond counts and value estimation, are also discussed. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1999
Adaptive flow management of multimedia data with a variable quality of service
- Authors: Littlejohn, Paul Stephen
- Date: 1999
- Subjects: Multimedia systems , Multimedia systems -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4605 , http://hdl.handle.net/10962/d1004863 , Multimedia systems , Multimedia systems -- Evaluation
- Description: Much of the current research involving the delivery of multimedia data focuses on the need to maintain a constant Quality of Service (QoS) throughout the lifetime of the connection. Delivery of a constant QoS requires that a guaranteed bandwidth is available for the entire connection. Techniques, such as resource reservation, are able to provide for this. These approaches work well across networks that are fairly homogeneous, and which have sufficient resources to sustain the guarantees, but are not currently viable over either heterogeneous or unreliable networks. To cater for the great number of networks (including the Internet) which do not conform to the ideal conditions required by constant Quality of Service mechanisms, this thesis proposes a different approach, that of dynamically adjusting the QoS in response to changing network conditions. Instead of optimizing the Quality of Service, the approach used in this thesis seeks to ensure the delivery of the information, at the best possible quality, as determined by the carrying ability of the poorest segment in the network link. To illustrate and examine this model, a service-adaptive system is described, which allows for the streaming of multimedia audio data across a network using the RealTime Transport Protocol. This application continually adjusts its service requests in response to the current network conditions. A client/server model is outlined whereby the server attempts to provide scalable media content, in this case audio data, to a client at the highest possible Quality of Service. The thesis presents and evaluates a number of renegotiation methods for adjusting the Quality of Service between the client and server. An A djusted QoS renegotiation method algorithm is suggested, which delivers the best possible quality, within an acceptable loss boundary.
- Full Text:
- Date Issued: 1999
- Authors: Littlejohn, Paul Stephen
- Date: 1999
- Subjects: Multimedia systems , Multimedia systems -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4605 , http://hdl.handle.net/10962/d1004863 , Multimedia systems , Multimedia systems -- Evaluation
- Description: Much of the current research involving the delivery of multimedia data focuses on the need to maintain a constant Quality of Service (QoS) throughout the lifetime of the connection. Delivery of a constant QoS requires that a guaranteed bandwidth is available for the entire connection. Techniques, such as resource reservation, are able to provide for this. These approaches work well across networks that are fairly homogeneous, and which have sufficient resources to sustain the guarantees, but are not currently viable over either heterogeneous or unreliable networks. To cater for the great number of networks (including the Internet) which do not conform to the ideal conditions required by constant Quality of Service mechanisms, this thesis proposes a different approach, that of dynamically adjusting the QoS in response to changing network conditions. Instead of optimizing the Quality of Service, the approach used in this thesis seeks to ensure the delivery of the information, at the best possible quality, as determined by the carrying ability of the poorest segment in the network link. To illustrate and examine this model, a service-adaptive system is described, which allows for the streaming of multimedia audio data across a network using the RealTime Transport Protocol. This application continually adjusts its service requests in response to the current network conditions. A client/server model is outlined whereby the server attempts to provide scalable media content, in this case audio data, to a client at the highest possible Quality of Service. The thesis presents and evaluates a number of renegotiation methods for adjusting the Quality of Service between the client and server. An A djusted QoS renegotiation method algorithm is suggested, which delivers the best possible quality, within an acceptable loss boundary.
- Full Text:
- Date Issued: 1999
An experimental study of the effect of Acacia mearnsii (black wattle trees) on streamflow in the Sand River, Eastern Cape
- Authors: Beyers, Gregory John
- Date: 1999
- Subjects: Wattles (Plants) -- South Africa , Wattles (Plants) -- South Africa -- Eastern Cape , Sand river (South africa) , Streamflow , Streamflow -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4832 , http://hdl.handle.net/10962/d1005507 , Wattles (Plants) -- South Africa , Wattles (Plants) -- South Africa -- Eastern Cape , Sand river (South africa) , Streamflow , Streamflow -- South Africa
- Description: This thesis explores the effect of Acacia mearnsii on streamflow in the Eastern Cape. There is a need for data on the localised effects of removing alien trees from the riparian zones within the Fynbos Biome. Fynbos catchments throughout the Western and Eastern Cape yield large quantities of good quality water which is an essential resource in the region. To convince local land owners to manage their riparian zones, small scale experimental results will prove invaluable to assure them of the immediate advantages for themselves and for downstream water users. Three permanent weirs were built 500 m apart to monitor the effect of removing A. mearnsii on streamflow in the Sand River, Eastern Cape. Consecutive weirs allowed for the comparison of streamflow between a cleared and uncleared section of the river without significant differences in riparian conditions, channel morphology and vegetation densities. A site survey confirmed comparable densities of A. mearnsii in both sections. A sample of trees was weighed and a relationship was found between diameter at breast height and above ground wet biomass. Between the first two weirs, 2.5 ha of riparian zone was cleared amounting to approximately 160tlha. Streamflow was monitored from the 10th of January 1996 to the 9th of September 1996. The average streamflow reduction for the duration of the experiment was 15.1 m³/ha/day or 551 mm per annum. Initially, after a period of above average rainfall, streamflow was augmented by discharge from the riparian zone but as conditions dried out, there was a net uptake of water with the highest average uptake of 23. 7m³/ha/day in June. A comparison between weather conditions and streamflow reduction indicated there is a complex relationship, with evidence of A. mearnsii exhibiting control of water loss during dry conditions. Acacia mearnsii trees in the riparian zone have been shown to cause significant streamflow reduction. Permanent weirs were found to be appropriate for this type of study. There is a need for further research on the effect of alien trees in riparian zones around South Africa as there is potential for significant increases in streamflow.
- Full Text:
- Date Issued: 1999
- Authors: Beyers, Gregory John
- Date: 1999
- Subjects: Wattles (Plants) -- South Africa , Wattles (Plants) -- South Africa -- Eastern Cape , Sand river (South africa) , Streamflow , Streamflow -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4832 , http://hdl.handle.net/10962/d1005507 , Wattles (Plants) -- South Africa , Wattles (Plants) -- South Africa -- Eastern Cape , Sand river (South africa) , Streamflow , Streamflow -- South Africa
- Description: This thesis explores the effect of Acacia mearnsii on streamflow in the Eastern Cape. There is a need for data on the localised effects of removing alien trees from the riparian zones within the Fynbos Biome. Fynbos catchments throughout the Western and Eastern Cape yield large quantities of good quality water which is an essential resource in the region. To convince local land owners to manage their riparian zones, small scale experimental results will prove invaluable to assure them of the immediate advantages for themselves and for downstream water users. Three permanent weirs were built 500 m apart to monitor the effect of removing A. mearnsii on streamflow in the Sand River, Eastern Cape. Consecutive weirs allowed for the comparison of streamflow between a cleared and uncleared section of the river without significant differences in riparian conditions, channel morphology and vegetation densities. A site survey confirmed comparable densities of A. mearnsii in both sections. A sample of trees was weighed and a relationship was found between diameter at breast height and above ground wet biomass. Between the first two weirs, 2.5 ha of riparian zone was cleared amounting to approximately 160tlha. Streamflow was monitored from the 10th of January 1996 to the 9th of September 1996. The average streamflow reduction for the duration of the experiment was 15.1 m³/ha/day or 551 mm per annum. Initially, after a period of above average rainfall, streamflow was augmented by discharge from the riparian zone but as conditions dried out, there was a net uptake of water with the highest average uptake of 23. 7m³/ha/day in June. A comparison between weather conditions and streamflow reduction indicated there is a complex relationship, with evidence of A. mearnsii exhibiting control of water loss during dry conditions. Acacia mearnsii trees in the riparian zone have been shown to cause significant streamflow reduction. Permanent weirs were found to be appropriate for this type of study. There is a need for further research on the effect of alien trees in riparian zones around South Africa as there is potential for significant increases in streamflow.
- Full Text:
- Date Issued: 1999
An investigation into the anxiolytic properties of melatonin in humans
- McCallaghan, Johannes Jacobus
- Authors: McCallaghan, Johannes Jacobus
- Date: 1999
- Subjects: Melatonin , Pineal gland -- Secretions
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3772 , http://hdl.handle.net/10962/d1003250 , Melatonin , Pineal gland -- Secretions
- Description: The purpose of this project was to investigate the role of melatonin in the pathophysiology of anxiety in humans. The literature study confirmed the intimate relationship between serotonin and melatonin. Melatonin is not only able to act as an agonist (in physiological concentrations) and an antagonist (at higher concentrations) on serotonin receptors but via control of brain pyridoxal kinase activity might have an effect on GABA, serotonin, dopamine and norepinephrine synthesis. A clinical trial to investigate melatonin's effect on anxiety in humans was conducted as a pilot study. Thirty patients complaining of anxiety participated in a liN of 1" double blind placebo controlled trial. During the experiment each subject was thus exposed to melatonin and a placebo for a week at a time on two occasions. During the first phase of the experiment, (Pair '1) patients showed a statistically significant reduction in their anxiety levels during the first period (P1P1), which was not the case during the second period (P1P2). The improvement however continued during the second phase of the experiment (Pair 2) so that there was also a statistically significant improvement during P 2 P 2 (Period 2 / Pair 2) when placebo was administered. It could not conclusively be shown that melatonin was responsible for the improvement in the patients' anxiety. The explanation for these results suggests thelt the improvement was due to a: 1) placebo effect throughout, 2) psychotherapeutic effect due to contact with a clinician, 3) melatonin induced phase shift in the patient's endogenous melatonin response curve, 4) combination of all 3 options. This pilot study lays the groundwork for a much more exhaustive study in which the melatonin of the patients is determined before melatonin is administered, the role of the clinician is clarified and the most appropriate time for melatonin administration is sought .
- Full Text:
- Date Issued: 1999
- Authors: McCallaghan, Johannes Jacobus
- Date: 1999
- Subjects: Melatonin , Pineal gland -- Secretions
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3772 , http://hdl.handle.net/10962/d1003250 , Melatonin , Pineal gland -- Secretions
- Description: The purpose of this project was to investigate the role of melatonin in the pathophysiology of anxiety in humans. The literature study confirmed the intimate relationship between serotonin and melatonin. Melatonin is not only able to act as an agonist (in physiological concentrations) and an antagonist (at higher concentrations) on serotonin receptors but via control of brain pyridoxal kinase activity might have an effect on GABA, serotonin, dopamine and norepinephrine synthesis. A clinical trial to investigate melatonin's effect on anxiety in humans was conducted as a pilot study. Thirty patients complaining of anxiety participated in a liN of 1" double blind placebo controlled trial. During the experiment each subject was thus exposed to melatonin and a placebo for a week at a time on two occasions. During the first phase of the experiment, (Pair '1) patients showed a statistically significant reduction in their anxiety levels during the first period (P1P1), which was not the case during the second period (P1P2). The improvement however continued during the second phase of the experiment (Pair 2) so that there was also a statistically significant improvement during P 2 P 2 (Period 2 / Pair 2) when placebo was administered. It could not conclusively be shown that melatonin was responsible for the improvement in the patients' anxiety. The explanation for these results suggests thelt the improvement was due to a: 1) placebo effect throughout, 2) psychotherapeutic effect due to contact with a clinician, 3) melatonin induced phase shift in the patient's endogenous melatonin response curve, 4) combination of all 3 options. This pilot study lays the groundwork for a much more exhaustive study in which the melatonin of the patients is determined before melatonin is administered, the role of the clinician is clarified and the most appropriate time for melatonin administration is sought .
- Full Text:
- Date Issued: 1999
An investigation into the use of IEEE 1394 for audio and control data distribution in music studio environments
- Authors: Laubscher, Robert Alan
- Date: 1999 , 2011-11-10
- Subjects: Digital electronics , Sound -- Recording and reproducing -- Digital techniques , MIDI (Standard) , Music -- Data processing , Computer sound processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4619 , http://hdl.handle.net/10962/d1006483 , Digital electronics , Sound -- Recording and reproducing -- Digital techniques , MIDI (Standard) , Music -- Data processing , Computer sound processing
- Description: This thesis investigates the feasibility of using a new digital interconnection technology, the IEEE-1394 High Performance Serial Bus, for audio and control data distribution in local and remote music recording studio environments. Current methods for connecting studio devices are described, and the need for a new digital interconnection technology explained. It is shown how this new interconnection technology and developing protocol standards make provision for multi-channel audio and control data distribution, routing, copyright protection, and device synchronisation. Feasibility is demonstrated by the implementation of a custom hardware and software solution. Remote music studio connectivity is considered, and the emerging standards and technologies for connecting future music studio utilising this new technology are discussed. , Microsoft Word , Adobe Acrobat 9.46 Paper Capture Plug-in
- Full Text:
- Date Issued: 1999
- Authors: Laubscher, Robert Alan
- Date: 1999 , 2011-11-10
- Subjects: Digital electronics , Sound -- Recording and reproducing -- Digital techniques , MIDI (Standard) , Music -- Data processing , Computer sound processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4619 , http://hdl.handle.net/10962/d1006483 , Digital electronics , Sound -- Recording and reproducing -- Digital techniques , MIDI (Standard) , Music -- Data processing , Computer sound processing
- Description: This thesis investigates the feasibility of using a new digital interconnection technology, the IEEE-1394 High Performance Serial Bus, for audio and control data distribution in local and remote music recording studio environments. Current methods for connecting studio devices are described, and the need for a new digital interconnection technology explained. It is shown how this new interconnection technology and developing protocol standards make provision for multi-channel audio and control data distribution, routing, copyright protection, and device synchronisation. Feasibility is demonstrated by the implementation of a custom hardware and software solution. Remote music studio connectivity is considered, and the emerging standards and technologies for connecting future music studio utilising this new technology are discussed. , Microsoft Word , Adobe Acrobat 9.46 Paper Capture Plug-in
- Full Text:
- Date Issued: 1999
An investigation of a framework to evaluate computer supported collaborative work
- Beauvais, Erik Alexander Maoui
- Authors: Beauvais, Erik Alexander Maoui
- Date: 1999
- Subjects: Computer networks , Teams in the workplace -- Data processing , Technology -- Data processing , Information technology -- Economic aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:1135 , http://hdl.handle.net/10962/d1002763 , Computer networks , Teams in the workplace -- Data processing , Technology -- Data processing , Information technology -- Economic aspects
- Description: Rapidly changing technology constantly modifies the way in which tasks are conceived and executed. Furthermore, leading organisations also encourage the use of new technology to support and establish innovative ways of doing business. For example, technology has helped to drive the globalization and tighter integration of world markets. This has facilitated, and even necessitated, business organisations to compete for work across national borders. For geographically dispersed organisations, collaboration has become critical. But this has presented time and space work complexities. Communication and collaboration technologies, for example, are needed to support such emerging co-operative business practices. The short development cycle of technology, communication and collaborative technologies included, leaves little time for testing and less for understanding the impact of new technology. To compound the problem, no established formulae exist for matching technology with work: over-investment is a waste of resources, while under-investment could lead to work failure. This research proposes a framework to assist organisations in selecting the appropriate level of technology with the work required. In this study, the methodology developed by the Evaluation Working Group, the DARPA Intelligent Collaboration and Visualization program is extended, and a matrix framework is constructed which compares the success of generic work tasks against a range of technology resources. The framework is tested using a low resource configuration, with selected work task types generally found in software development. (The Joint Application Development (JAD) methodology for software development is used as the contextual basis of the experiment.) All activities are evaluated according to selected measure components of success. A collection of research methods known as ethnography is used to examine and test the framework. Methods employed include questionnaires, interviews, interaction analysis and ethnomethodology. The results indicate that even at a low resource level, given selected criteria, collaborative technology successfully supports certain collaborative work activities. Findings also indicate that softer people issues require much more attention in order for technology to support natural collaborative work. Finally, user defined parameter testing has indicated that the framework functions as expected and designed.
- Full Text:
- Date Issued: 1999
- Authors: Beauvais, Erik Alexander Maoui
- Date: 1999
- Subjects: Computer networks , Teams in the workplace -- Data processing , Technology -- Data processing , Information technology -- Economic aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:1135 , http://hdl.handle.net/10962/d1002763 , Computer networks , Teams in the workplace -- Data processing , Technology -- Data processing , Information technology -- Economic aspects
- Description: Rapidly changing technology constantly modifies the way in which tasks are conceived and executed. Furthermore, leading organisations also encourage the use of new technology to support and establish innovative ways of doing business. For example, technology has helped to drive the globalization and tighter integration of world markets. This has facilitated, and even necessitated, business organisations to compete for work across national borders. For geographically dispersed organisations, collaboration has become critical. But this has presented time and space work complexities. Communication and collaboration technologies, for example, are needed to support such emerging co-operative business practices. The short development cycle of technology, communication and collaborative technologies included, leaves little time for testing and less for understanding the impact of new technology. To compound the problem, no established formulae exist for matching technology with work: over-investment is a waste of resources, while under-investment could lead to work failure. This research proposes a framework to assist organisations in selecting the appropriate level of technology with the work required. In this study, the methodology developed by the Evaluation Working Group, the DARPA Intelligent Collaboration and Visualization program is extended, and a matrix framework is constructed which compares the success of generic work tasks against a range of technology resources. The framework is tested using a low resource configuration, with selected work task types generally found in software development. (The Joint Application Development (JAD) methodology for software development is used as the contextual basis of the experiment.) All activities are evaluated according to selected measure components of success. A collection of research methods known as ethnography is used to examine and test the framework. Methods employed include questionnaires, interviews, interaction analysis and ethnomethodology. The results indicate that even at a low resource level, given selected criteria, collaborative technology successfully supports certain collaborative work activities. Findings also indicate that softer people issues require much more attention in order for technology to support natural collaborative work. Finally, user defined parameter testing has indicated that the framework functions as expected and designed.
- Full Text:
- Date Issued: 1999
An object-oriented toolkit for music notation
- Authors: Eales, Andrew Arnold
- Date: 1999 , 2000-04-26
- Subjects: Musical notation , Object-oriented programming (Computer science) , Computer music -- History and criticism , Musical notation -- Software
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4618 , http://hdl.handle.net/10962/d1006473 , Musical notation , Object-oriented programming (Computer science) , Computer music -- History and criticism , Musical notation -- Software
- Description: This thesis investigates the design and implementation of an object-oriented toolkit for music notation. It considers whether object-oriented technology provides features that are desirable for representing music notation. The ability to sympathetically represent the conventions of music notation provides software tools that are flexible to use, and easily extended to represent less common features of music notation. The design and implementation of an object-oriented class hierarchy that captures the structural and semantic relationships of music notation symbols is described. Functions that search for symbols, and update symbol positions are also implemented. Traditional context-sensitive and spatial relationships between music symbols may be maintained, or extended to provide notational features found in modern music. MIDI functionality includes the ability to play music notation and to allow step-recording of MIDI events. The toolkit has been designed to simplify the creation of applications that make use of music notation; example applications are created to demonstrate its capabilities. , Microsoft Word , Adobe Acrobat 9.46 Paper Capture Plug-in
- Full Text:
- Date Issued: 1999
- Authors: Eales, Andrew Arnold
- Date: 1999 , 2000-04-26
- Subjects: Musical notation , Object-oriented programming (Computer science) , Computer music -- History and criticism , Musical notation -- Software
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4618 , http://hdl.handle.net/10962/d1006473 , Musical notation , Object-oriented programming (Computer science) , Computer music -- History and criticism , Musical notation -- Software
- Description: This thesis investigates the design and implementation of an object-oriented toolkit for music notation. It considers whether object-oriented technology provides features that are desirable for representing music notation. The ability to sympathetically represent the conventions of music notation provides software tools that are flexible to use, and easily extended to represent less common features of music notation. The design and implementation of an object-oriented class hierarchy that captures the structural and semantic relationships of music notation symbols is described. Functions that search for symbols, and update symbol positions are also implemented. Traditional context-sensitive and spatial relationships between music symbols may be maintained, or extended to provide notational features found in modern music. MIDI functionality includes the ability to play music notation and to allow step-recording of MIDI events. The toolkit has been designed to simplify the creation of applications that make use of music notation; example applications are created to demonstrate its capabilities. , Microsoft Word , Adobe Acrobat 9.46 Paper Capture Plug-in
- Full Text:
- Date Issued: 1999
Buffering strategies and bandwidth renegotiation for MPEG video streams
- Authors: Schonken, Nico
- Date: 1999
- Subjects: Video compression , Computer algorithms , Digital video
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4651 , http://hdl.handle.net/10962/d1006620 , Video compression , Computer algorithms , Digital video
- Description: This paper confirms the existence of short-term and long-term variation of the required bandwidth for MPEG videostreams. We show how the use of a small amount of buffering and GOP grouping can significantly reduce the effect of the short-term variation. By introducing a number of bandwidth renegotiation techniques, which can be applied to MPEG video streams in general, we are able to reduce the effect of long-term variation. These techniques include those that need the a priori knowledge of frame sizes as well as one that can renegotiate dynamically. A costing algorithm has also been introduced in order to compare various proposals against each other.
- Full Text:
- Date Issued: 1999
- Authors: Schonken, Nico
- Date: 1999
- Subjects: Video compression , Computer algorithms , Digital video
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4651 , http://hdl.handle.net/10962/d1006620 , Video compression , Computer algorithms , Digital video
- Description: This paper confirms the existence of short-term and long-term variation of the required bandwidth for MPEG videostreams. We show how the use of a small amount of buffering and GOP grouping can significantly reduce the effect of the short-term variation. By introducing a number of bandwidth renegotiation techniques, which can be applied to MPEG video streams in general, we are able to reduce the effect of long-term variation. These techniques include those that need the a priori knowledge of frame sizes as well as one that can renegotiate dynamically. A costing algorithm has also been introduced in order to compare various proposals against each other.
- Full Text:
- Date Issued: 1999
Conservation biology and management of the Twee River redfin, Barbus erubescens (Pisces : Cyprinide)
- Authors: Marriott, Michael Stephen
- Date: 1999
- Subjects: Barbus , Cyprinidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5248 , http://hdl.handle.net/10962/d1005091 , Barbus , Cyprinidae
- Description: Agricultural practices and increasing levels of pollution, water abstraction and numbers of predatory exotic fishes gave rise to mounting concern for the survival of the already endangered Twee River redfin, Barbus erubescens. Numbers were believed to be dwindling and an urgent re-assessment of the species' conservation status and major threats was called for. Distribution and estimated numbers of B. erubescens were detennined from a census conducted in the Twee River catclunent, and baseline knowledge of age and growth, reproduction, diet and habitat preferences was gained from biological work on collected specimens. Such understanding was necessary to formullate management ideas. Although an estimated 40% reduction in area of occupancy has occurred in the middle reaches of the Twee River system, the known distribution of B. erubescens was extended into the upper Suurvlei River. Despite fragmentation, surviving redfin populations remained healthy and total population size was estimated at 8400 individuals, 4100 of which were considered mature. Adults preferred pools with water exceeding 1 m in depth and tended to be associated with sandy or boulder substrates. Due to low numbers no such study was conducted on juveniles, although observations indicated a preference for the upper 50 cm of the water column, in or around marginal vegetation. Barbus erubescens spawn in summer and follow an asynchronous, iteroparous pattern. Males and females reach a maximum age of six years, maturing after two years at calculated SL of 45 mm in males and 42 mm in females. The diet was dominated by simulid and ephemeropteran larvae. Although the combined pressures of pesticide and fertiliser use, predation and competition from exotic species have undoubtedly had a negative impact on B. erubescens, the species has maintained viable populations. With continued expansion of these threats the focus of conservation attention may change but, at present, it is most likely agricultural water use, amounting to 7.43 x 10⁶ m³y⁻¹, 15% of the entire catchment production, which poses the greatest immediate threat to the survival of the species. Based on a deteriorating habitat and restricted area of occupancy, B. erubescens was rated Critically Endangered, and it is recommended that a conservation management plan be implemented in the Twee River catchment. The focus of such action should be on genetic preservation, with immediate projects including gamete cryopreservation and captive breeding and rearing programmes. Catchment management, including education and rehabilitation programmes, must be the long-term aim of conservation, to ensure the survival of B. erubescens.
- Full Text:
- Date Issued: 1999
Conservation biology and management of the Twee River redfin, Barbus erubescens (Pisces : Cyprinide)
- Authors: Marriott, Michael Stephen
- Date: 1999
- Subjects: Barbus , Cyprinidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5248 , http://hdl.handle.net/10962/d1005091 , Barbus , Cyprinidae
- Description: Agricultural practices and increasing levels of pollution, water abstraction and numbers of predatory exotic fishes gave rise to mounting concern for the survival of the already endangered Twee River redfin, Barbus erubescens. Numbers were believed to be dwindling and an urgent re-assessment of the species' conservation status and major threats was called for. Distribution and estimated numbers of B. erubescens were detennined from a census conducted in the Twee River catclunent, and baseline knowledge of age and growth, reproduction, diet and habitat preferences was gained from biological work on collected specimens. Such understanding was necessary to formullate management ideas. Although an estimated 40% reduction in area of occupancy has occurred in the middle reaches of the Twee River system, the known distribution of B. erubescens was extended into the upper Suurvlei River. Despite fragmentation, surviving redfin populations remained healthy and total population size was estimated at 8400 individuals, 4100 of which were considered mature. Adults preferred pools with water exceeding 1 m in depth and tended to be associated with sandy or boulder substrates. Due to low numbers no such study was conducted on juveniles, although observations indicated a preference for the upper 50 cm of the water column, in or around marginal vegetation. Barbus erubescens spawn in summer and follow an asynchronous, iteroparous pattern. Males and females reach a maximum age of six years, maturing after two years at calculated SL of 45 mm in males and 42 mm in females. The diet was dominated by simulid and ephemeropteran larvae. Although the combined pressures of pesticide and fertiliser use, predation and competition from exotic species have undoubtedly had a negative impact on B. erubescens, the species has maintained viable populations. With continued expansion of these threats the focus of conservation attention may change but, at present, it is most likely agricultural water use, amounting to 7.43 x 10⁶ m³y⁻¹, 15% of the entire catchment production, which poses the greatest immediate threat to the survival of the species. Based on a deteriorating habitat and restricted area of occupancy, B. erubescens was rated Critically Endangered, and it is recommended that a conservation management plan be implemented in the Twee River catchment. The focus of such action should be on genetic preservation, with immediate projects including gamete cryopreservation and captive breeding and rearing programmes. Catchment management, including education and rehabilitation programmes, must be the long-term aim of conservation, to ensure the survival of B. erubescens.
- Full Text:
- Date Issued: 1999
Effects of zone and wave exposure on population structure and recruitment of the mussel (Perna perna) in South Africa
- Authors: Lindsay, Justin Robert
- Date: 1999
- Subjects: Perna -- South Africa , Perna -- Growth , Mussels -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5685 , http://hdl.handle.net/10962/d1005371 , Perna -- South Africa , Perna -- Growth , Mussels -- South Africa
- Description:
Certain aspects of the population dynamics of the brown mussel, Perna perna, were examined at 18 sites along the south coast of South African. Specifically the effects of wave exposure and tidal height were examined in relation to mussel size, biomass and density. A single set of samples was removed from each of the 18 sites, over three spring tide cycles. Sites were classified as exposed or sheltered prior to sampling. Principal component analysis (PCA) (based on mussel length data) and length frequency histograms revealed that there was a general decrease in the modal size of the adult mussel cohort with an increase in tidal height. The effects of exposure on mussel size decreased higher on the shore. On the exposed low shore the maximum size of mussels had a mean length of 102.3mm and was significantly larger (ANOVA, p<0.0001) than that for mussels on sheltered shores (86.7mm). The difference between mean maximum lengths of mussels on the mid shore was not so great, exposed sites had a average mean maximum length of 79.9, while on the sheltered shores it was 68.4mm. On the high shore the difference between the average mean maximum lengths at exposed and sheltered sites was only 3.9mm. The fact that the effects of exposure were greatest on the low shore was also borne out in the PCA. In this analysis low shore exposed and sheltered zones separated into two groups with little overlap, mid shore exposed and sheltered zones were positioned next to each other, and exposed and sheltered high shore zones were clumped together. Densities of adult mussels (>l5mm) were calculated as real densities from randomly placed quads i.e. not from areas of 100% cover. Density decreased up the shore; low, mid and high shore zones were significantly different from each other (ANOVA , p<0.0001; followed by multiple range tests). There was no significant difference between the densities of mussels at exposed and sheltered sites within each zone (ANOVA, p=0.7155). Recruit (
- Full Text:
- Date Issued: 1999
- Authors: Lindsay, Justin Robert
- Date: 1999
- Subjects: Perna -- South Africa , Perna -- Growth , Mussels -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5685 , http://hdl.handle.net/10962/d1005371 , Perna -- South Africa , Perna -- Growth , Mussels -- South Africa
- Description:
Certain aspects of the population dynamics of the brown mussel, Perna perna, were examined at 18 sites along the south coast of South African. Specifically the effects of wave exposure and tidal height were examined in relation to mussel size, biomass and density. A single set of samples was removed from each of the 18 sites, over three spring tide cycles. Sites were classified as exposed or sheltered prior to sampling. Principal component analysis (PCA) (based on mussel length data) and length frequency histograms revealed that there was a general decrease in the modal size of the adult mussel cohort with an increase in tidal height. The effects of exposure on mussel size decreased higher on the shore. On the exposed low shore the maximum size of mussels had a mean length of 102.3mm and was significantly larger (ANOVA, p<0.0001) than that for mussels on sheltered shores (86.7mm). The difference between mean maximum lengths of mussels on the mid shore was not so great, exposed sites had a average mean maximum length of 79.9, while on the sheltered shores it was 68.4mm. On the high shore the difference between the average mean maximum lengths at exposed and sheltered sites was only 3.9mm. The fact that the effects of exposure were greatest on the low shore was also borne out in the PCA. In this analysis low shore exposed and sheltered zones separated into two groups with little overlap, mid shore exposed and sheltered zones were positioned next to each other, and exposed and sheltered high shore zones were clumped together. Densities of adult mussels (>l5mm) were calculated as real densities from randomly placed quads i.e. not from areas of 100% cover. Density decreased up the shore; low, mid and high shore zones were significantly different from each other (ANOVA , p<0.0001; followed by multiple range tests). There was no significant difference between the densities of mussels at exposed and sheltered sites within each zone (ANOVA, p=0.7155). Recruit (
- Full Text:
- Date Issued: 1999
Electrochemical studies of gold bioaccumulation by yeast cell wall components
- Authors: Lack, Barbara Anne
- Date: 1999
- Subjects: Hydrometallurgy , Electrochemical analysis , Gold ores , Gold
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4311 , http://hdl.handle.net/10962/d1004969 , Hydrometallurgy , Electrochemical analysis , Gold ores , Gold
- Description: Gold, amongst other group 11 metals, was almost certainly one of the first three metals known to man. In addition to the economic importance of the metal, gold has a wide variety of applications in the medical, electrocatalytical and micro-electronics fields. However, the determination of gold ions in solution, with accuracy, precision, sensitivity and selectivity is still an interesting and much debated topic in analytical chemistry. A system whereby gold ions have been successfully detected employing an electrochemical technique, known as stripping voltammetry, has been developed. The electrochemical method was chosen over other available techniques for the sensitivity, particularly at low concentrations, and selectivity properties; notably in the presence of other metal ions. Under acidic conditions, the electrochemical technique was applied and the presence of gold(III), at a concentration of 2.53 x 10⁻⁵ mol dm⁻³ in a mine waste water sample, was detected. Biomass, in particular yeast and algal types, have been successfully employed in extracting low concentrations of gold ions from industrial effluents. The manipulation of the biological facility for mineral interaction, biohydrometallurgy, may yield numerous potential new technologies. South Africa in particular would benefit from this area of research, since the country is a major ore and metal refining country and if the output and the efficiency of the mines could be improved, even by a small percentage, the financial rewards would be vast. In this study, the application of adsorptive cathodic stripping voltammetry (AdCSV) of gold(III) in the presence of various Saccharomyces cerevisiae cell wall components, was investigated to determine which, if any, were involved specifically in the chemical binding of the gold ions. The chitin and mannan extracts showed the most promise with detection limits of 1.10 x 10⁻⁶ mol dm⁻³ and 9 x 10⁻⁹ mol dm⁻³, respectively; employing the AdCSV technique. A modification of the stripping voltammetry technique, Osteryoung square wave stripping voltammetry (OSWSV), provided the lowest detection limit, for gold(IIl) in the presence of mannan, of 1.70 x 10⁻¹¹ mol dm⁻³ ; utilising a modified carbon paste electrode. The detection of gold(III) has been shown to be dependent on the type of electrode employed, the electrolyte solution and the presence of interfering agents. The effect of copper(II) and silver(I) on the detection of the gold(III) in solution was investigated; whilst the silver(I) has shown no detrimental effects on gold (III) detection systems, copper(II) has indicated the possibility of forming an inter-metallic compound with the gold(III). However, mannan has shown to selectively and preferentially bind the gold(III) in the presence of a ten-fold excess of copper(II). Nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy, as well as computer modelling techniques were employed to further investIgate the mannan-gold(III) interaction and proposed complex formed. The NMR, IR and computer modelling data are in agreement with the electrochemical data on proposing a mannan-gold(III) complex. The co-ordination site was established to be in the vicinity of the H-I and H-2 protons and the gold(III) adopts a square-planar geometry upon co-ordination. The benefits of the research are useful from a biological perspective (i. e. as more is known about the binding sites, microbiologists/biochemists may work on the optimisation of parameters for these sites or work could be furthered into the enhanced expression of the sites) and an industrial one. In addition to the' two major benefits, an improved understanding of gold and its chemistry would be achieved, which is advantageous for other fields of research as well.
- Full Text:
- Date Issued: 1999
- Authors: Lack, Barbara Anne
- Date: 1999
- Subjects: Hydrometallurgy , Electrochemical analysis , Gold ores , Gold
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4311 , http://hdl.handle.net/10962/d1004969 , Hydrometallurgy , Electrochemical analysis , Gold ores , Gold
- Description: Gold, amongst other group 11 metals, was almost certainly one of the first three metals known to man. In addition to the economic importance of the metal, gold has a wide variety of applications in the medical, electrocatalytical and micro-electronics fields. However, the determination of gold ions in solution, with accuracy, precision, sensitivity and selectivity is still an interesting and much debated topic in analytical chemistry. A system whereby gold ions have been successfully detected employing an electrochemical technique, known as stripping voltammetry, has been developed. The electrochemical method was chosen over other available techniques for the sensitivity, particularly at low concentrations, and selectivity properties; notably in the presence of other metal ions. Under acidic conditions, the electrochemical technique was applied and the presence of gold(III), at a concentration of 2.53 x 10⁻⁵ mol dm⁻³ in a mine waste water sample, was detected. Biomass, in particular yeast and algal types, have been successfully employed in extracting low concentrations of gold ions from industrial effluents. The manipulation of the biological facility for mineral interaction, biohydrometallurgy, may yield numerous potential new technologies. South Africa in particular would benefit from this area of research, since the country is a major ore and metal refining country and if the output and the efficiency of the mines could be improved, even by a small percentage, the financial rewards would be vast. In this study, the application of adsorptive cathodic stripping voltammetry (AdCSV) of gold(III) in the presence of various Saccharomyces cerevisiae cell wall components, was investigated to determine which, if any, were involved specifically in the chemical binding of the gold ions. The chitin and mannan extracts showed the most promise with detection limits of 1.10 x 10⁻⁶ mol dm⁻³ and 9 x 10⁻⁹ mol dm⁻³, respectively; employing the AdCSV technique. A modification of the stripping voltammetry technique, Osteryoung square wave stripping voltammetry (OSWSV), provided the lowest detection limit, for gold(IIl) in the presence of mannan, of 1.70 x 10⁻¹¹ mol dm⁻³ ; utilising a modified carbon paste electrode. The detection of gold(III) has been shown to be dependent on the type of electrode employed, the electrolyte solution and the presence of interfering agents. The effect of copper(II) and silver(I) on the detection of the gold(III) in solution was investigated; whilst the silver(I) has shown no detrimental effects on gold (III) detection systems, copper(II) has indicated the possibility of forming an inter-metallic compound with the gold(III). However, mannan has shown to selectively and preferentially bind the gold(III) in the presence of a ten-fold excess of copper(II). Nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy, as well as computer modelling techniques were employed to further investIgate the mannan-gold(III) interaction and proposed complex formed. The NMR, IR and computer modelling data are in agreement with the electrochemical data on proposing a mannan-gold(III) complex. The co-ordination site was established to be in the vicinity of the H-I and H-2 protons and the gold(III) adopts a square-planar geometry upon co-ordination. The benefits of the research are useful from a biological perspective (i. e. as more is known about the binding sites, microbiologists/biochemists may work on the optimisation of parameters for these sites or work could be furthered into the enhanced expression of the sites) and an industrial one. In addition to the' two major benefits, an improved understanding of gold and its chemistry would be achieved, which is advantageous for other fields of research as well.
- Full Text:
- Date Issued: 1999
Evaluation of a 'defouling on demand' strategy for the ultrafiltration of brown water using activatable enzymes
- Authors: Buchanan, K
- Date: 1999
- Subjects: Water -- Purification , Ultrafiltration , Enzymes , Membranes (Technology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3904 , http://hdl.handle.net/10962/d1003963 , Water -- Purification , Ultrafiltration , Enzymes , Membranes (Technology)
- Description: New approaches to the application of membranes for the production of potable water are constantly being sought after in anticipation of future demands for increasingly rigorous water quality standards and reduced environmental impact. A major limitation, however, is membrane fouling, which manifests itself as a continual reduction in flux over time and thus restricts the practical implementation to restore flux. Mechanical and chemical methods have been implemented to restore flux to ultrafiltration systems, but these either result in a break in the process operation or lead to membrane damage or additional pollution problems. This project was aimed to develop a 'defouling on demand' stategy for cleaning membranes used during brown water ultrafiltration. The process involves the use of activatable peroxidase enzymes, which were immobilised onto flat sheet polysulphone membranes. Following flux decline which reaches a critical level with the build-up of the foulant layer, the immobilised enzyme layer was activated by the addition of a chemical activator solution, in this case hydrogen peroxidase and manganous sulphate. Manganese peroxidase was found to be the most effective enzyme at alleviating fouling by degrading the foulant layer formed on the membrane surface and hence restored flux to the ultrafiltration system. A 93% flux improvement was observed when manganese peroxidase was activated when 800uM manganous sulphate, 100mM hydrogen peroxide were added in the presence of a manganese chelator, lactate. The concept and the potential benefits this system holds will be discussed in further detail.
- Full Text:
- Date Issued: 1999
- Authors: Buchanan, K
- Date: 1999
- Subjects: Water -- Purification , Ultrafiltration , Enzymes , Membranes (Technology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3904 , http://hdl.handle.net/10962/d1003963 , Water -- Purification , Ultrafiltration , Enzymes , Membranes (Technology)
- Description: New approaches to the application of membranes for the production of potable water are constantly being sought after in anticipation of future demands for increasingly rigorous water quality standards and reduced environmental impact. A major limitation, however, is membrane fouling, which manifests itself as a continual reduction in flux over time and thus restricts the practical implementation to restore flux. Mechanical and chemical methods have been implemented to restore flux to ultrafiltration systems, but these either result in a break in the process operation or lead to membrane damage or additional pollution problems. This project was aimed to develop a 'defouling on demand' stategy for cleaning membranes used during brown water ultrafiltration. The process involves the use of activatable peroxidase enzymes, which were immobilised onto flat sheet polysulphone membranes. Following flux decline which reaches a critical level with the build-up of the foulant layer, the immobilised enzyme layer was activated by the addition of a chemical activator solution, in this case hydrogen peroxidase and manganous sulphate. Manganese peroxidase was found to be the most effective enzyme at alleviating fouling by degrading the foulant layer formed on the membrane surface and hence restored flux to the ultrafiltration system. A 93% flux improvement was observed when manganese peroxidase was activated when 800uM manganous sulphate, 100mM hydrogen peroxide were added in the presence of a manganese chelator, lactate. The concept and the potential benefits this system holds will be discussed in further detail.
- Full Text:
- Date Issued: 1999
Hydrogeology of the Queenstown 1:500 000 map region (Sheet 3126)
- Authors: Smart, Michael Charles
- Date: 1999
- Subjects: Hydrogeology , Hydrogeology Maps , Hydrogeology -- South Africa -- Queenstown
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4971 , http://hdl.handle.net/10962/d1005583 , Hydrogeology , Hydrogeology Maps , Hydrogeology -- South Africa -- Queenstown
- Description: The Groundwater characteristics of a portion of the Eastern Cape are depicted on a General Hydrogeological Map (Queenstown 3126) at 1 :500 000 scale. The purpose of the map and accompanying text is to provide a synoptic overview of the hydrogeology of the area. The "fractured and intergranular" aquifer type predominates in the more humid eastern part of the study area where the lithologies are more highly weathered whereas the fractured type predominates in the drier west. For the bulk of the area borehole yields are in the 0.5 - 2.0 ℓ/sec range. Higher yields (in the 2.0 - 5.0 ℓ/sec range) are common only in a small area in the south-west of the map. Lowest yields (0.1 - 0.5 ℓ/sec) are obtained in an area immediately north of East London and in the Dwyka Group near the NE coast. It is important to note that these yield ranges are merely a measure of the central tendency, and that higher yields - in excess of 3 ℓ/sec - could well be obtainable at optimal hydrogeological target features within these areas. Highest borehole yields are obtained in folded areas (restricted to the southern edge of the study area) followed by rocks with dolerite intrusions (common over the bulk of the study area). Other targets include fractured sedimentary and volcanic rock and unconsolidated deposits. Yields obtained from dolerite contact zones vary across the area; differences correspond to spatial variations in the style of intrusion. Highest success rates are obtained in areas intruded by a combination of dykes, ring-shaped sheets and irregular sheets while poor results are obtained in areas intruded by thick massive sills. Air photo and satellite image interpretation, geological mapping, magnetic, electrical resistivity and electromagnetic geophysical methods can be used to locate drilling target features. Groundwater quality is good since electrical conductivities over much of the area are lower than 70 mS/m and rarely exceed the South African Water quality guideline limit for human consumption of 300 mS/m. The volume of groundwater abstractable ranges between approximately 2 000 m³/km²/annum and 80 000 m³/km²/annum and is limited by either volumes of recharge or subsurface storage.
- Full Text:
- Date Issued: 1999
- Authors: Smart, Michael Charles
- Date: 1999
- Subjects: Hydrogeology , Hydrogeology Maps , Hydrogeology -- South Africa -- Queenstown
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4971 , http://hdl.handle.net/10962/d1005583 , Hydrogeology , Hydrogeology Maps , Hydrogeology -- South Africa -- Queenstown
- Description: The Groundwater characteristics of a portion of the Eastern Cape are depicted on a General Hydrogeological Map (Queenstown 3126) at 1 :500 000 scale. The purpose of the map and accompanying text is to provide a synoptic overview of the hydrogeology of the area. The "fractured and intergranular" aquifer type predominates in the more humid eastern part of the study area where the lithologies are more highly weathered whereas the fractured type predominates in the drier west. For the bulk of the area borehole yields are in the 0.5 - 2.0 ℓ/sec range. Higher yields (in the 2.0 - 5.0 ℓ/sec range) are common only in a small area in the south-west of the map. Lowest yields (0.1 - 0.5 ℓ/sec) are obtained in an area immediately north of East London and in the Dwyka Group near the NE coast. It is important to note that these yield ranges are merely a measure of the central tendency, and that higher yields - in excess of 3 ℓ/sec - could well be obtainable at optimal hydrogeological target features within these areas. Highest borehole yields are obtained in folded areas (restricted to the southern edge of the study area) followed by rocks with dolerite intrusions (common over the bulk of the study area). Other targets include fractured sedimentary and volcanic rock and unconsolidated deposits. Yields obtained from dolerite contact zones vary across the area; differences correspond to spatial variations in the style of intrusion. Highest success rates are obtained in areas intruded by a combination of dykes, ring-shaped sheets and irregular sheets while poor results are obtained in areas intruded by thick massive sills. Air photo and satellite image interpretation, geological mapping, magnetic, electrical resistivity and electromagnetic geophysical methods can be used to locate drilling target features. Groundwater quality is good since electrical conductivities over much of the area are lower than 70 mS/m and rarely exceed the South African Water quality guideline limit for human consumption of 300 mS/m. The volume of groundwater abstractable ranges between approximately 2 000 m³/km²/annum and 80 000 m³/km²/annum and is limited by either volumes of recharge or subsurface storage.
- Full Text:
- Date Issued: 1999
Physiological and non-physiological induction of gastrointestinal differentiation
- Authors: Brauns, Seth Clint Aron
- Date: 1999
- Subjects: Gastrointestinal system -- Differentiation , Gastrointestinal system -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11089 , http://hdl.handle.net/10948/d1015521
- Description: The human colonic carcinoma cell lines HT-29 and Caco-2 both exhibit structural and functional differentiation under appropriate culture conditions. HT-29 can be induced to differentiate by treatment with short-chain fatty acids or acetoacetate. Caco-2 cells differentiate spontaneously upon contact inhibition. In this study HT-29 cells were treated with 5 mM acetate, propionate, butyrate and acetoacetate (physiological inducers) to assess their effects on the expression of carbonic anhydrase 1, sucrase-isomaltase and alkaline phosphatase which are reported to be markers of gastrointestinal differentiation. The maturation induction observed was compared to that of the spontaneous differentiation observed in Caco-2 cells. Assays were performed over an 18 day period. Results showed a close correlation (p < 0.05) between HT-29 and Caco-2 cell on days 4 and 12. These results indicate that differentiation reported in both cell lines is comparable and can be used as a basis for further comparative studies. In addition, parallel experiments to the above were conducted using a selection of nine rationally designed cyclic dipeptides (CDPs) potential drug entities which were chosen as non-physiological inducers. The results showed that the cyclic dipeptides were able to induce the gastrointestinal phenotype as observed in HT-29 cells treated with physiological inducers. Studies on the effects of energy-related metabolism in HT-29 and Caco-2 cells as induced by physiological and non-physiological inducers indicated that energy metabolism is a significant role player in gastrointestinal differentiation. The results reported show a decrease in ATP concentrations indicating that the cyclic dipeptides, like physiological inducers, affect the energy state of the HT-29 cells and thus may effect the differentiation of these cells. A positive correlation was found between histone phsophorylation and differentiation confirming that histone phsophorylation was partly responsible for the decrease in ATP concentrations. It is suggested that the induction of differentiation in HT- 29 cells could be either due to non-specific transcription of genes by activation of a chromatin switch or specific by the activation of signal transduction pathways based on the flux of ATP through the cells. Differential display RT-PCR is probably the most sensitive method that could be used to validate the suggestion of either a nonspecific transcription of genes or a specific differentiation reported for HT-29 cells.
- Full Text:
- Date Issued: 1999
- Authors: Brauns, Seth Clint Aron
- Date: 1999
- Subjects: Gastrointestinal system -- Differentiation , Gastrointestinal system -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11089 , http://hdl.handle.net/10948/d1015521
- Description: The human colonic carcinoma cell lines HT-29 and Caco-2 both exhibit structural and functional differentiation under appropriate culture conditions. HT-29 can be induced to differentiate by treatment with short-chain fatty acids or acetoacetate. Caco-2 cells differentiate spontaneously upon contact inhibition. In this study HT-29 cells were treated with 5 mM acetate, propionate, butyrate and acetoacetate (physiological inducers) to assess their effects on the expression of carbonic anhydrase 1, sucrase-isomaltase and alkaline phosphatase which are reported to be markers of gastrointestinal differentiation. The maturation induction observed was compared to that of the spontaneous differentiation observed in Caco-2 cells. Assays were performed over an 18 day period. Results showed a close correlation (p < 0.05) between HT-29 and Caco-2 cell on days 4 and 12. These results indicate that differentiation reported in both cell lines is comparable and can be used as a basis for further comparative studies. In addition, parallel experiments to the above were conducted using a selection of nine rationally designed cyclic dipeptides (CDPs) potential drug entities which were chosen as non-physiological inducers. The results showed that the cyclic dipeptides were able to induce the gastrointestinal phenotype as observed in HT-29 cells treated with physiological inducers. Studies on the effects of energy-related metabolism in HT-29 and Caco-2 cells as induced by physiological and non-physiological inducers indicated that energy metabolism is a significant role player in gastrointestinal differentiation. The results reported show a decrease in ATP concentrations indicating that the cyclic dipeptides, like physiological inducers, affect the energy state of the HT-29 cells and thus may effect the differentiation of these cells. A positive correlation was found between histone phsophorylation and differentiation confirming that histone phsophorylation was partly responsible for the decrease in ATP concentrations. It is suggested that the induction of differentiation in HT- 29 cells could be either due to non-specific transcription of genes by activation of a chromatin switch or specific by the activation of signal transduction pathways based on the flux of ATP through the cells. Differential display RT-PCR is probably the most sensitive method that could be used to validate the suggestion of either a nonspecific transcription of genes or a specific differentiation reported for HT-29 cells.
- Full Text:
- Date Issued: 1999
Population dynamics and growth rates of the brown mussel (Perna perna) on wave exposed and wave sheltered shores of South Africa
- Authors: Lindsay, Tracy Lynn
- Date: 1999
- Subjects: Perna -- South Africa , Mussels -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5741 , http://hdl.handle.net/10962/d1005427 , Perna -- South Africa , Mussels -- South Africa
- Description:
Population dynamics of Perna perna in low shore mussel beds were investigated over a 15 month period at six sites along the south coast of South Africa, with particular reference to the effects of wave exposure. The degree of exposure was first quantitatively ascertained using the dissolution of cement blocks to measure average wave force and dynamometers to measure maximum wave force. The mean mass loss of the cement blocks was higher at Diaz Cross and Kwaai Hoek than at Mgwalana, Rufanes and Riet River. No data were available for Fish River. The mean maximum wave force encountered at Diaz Cross, Kwaai Hoek and Fish River was significantly higher (p
15 mm) were positively correlated with recruit densities (1-5 mm) for both shore types (p 15 mm) was significantly lower on exposed (mean of 3 348.m⁻²) than on sheltered shores (mean of 4 796.m⁻²) (p O.05). The effect of exposure on growth rate formed the focal point of this study and was determined using three different approaches. The first technique, mark-recapture, involved filing notches on the growing edges of mussels in the field. After 111 days, mussels were removed and the growth measured. The second approach used internal growth bands to measure growth rates, once the periodicity with which these bands were laid down was established. Thirdly, using Shepherd's length composition analysis (SLCA), growth rates were determined from length frequency distributions in 11 samples taken over 15 months. The general conclusion from all three approaches was that growth rate was twice as fast on the exposed shores as on the sheltered shores (p - Full Text:
- Date Issued: 1999
- Authors: Lindsay, Tracy Lynn
- Date: 1999
- Subjects: Perna -- South Africa , Mussels -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5741 , http://hdl.handle.net/10962/d1005427 , Perna -- South Africa , Mussels -- South Africa
- Description:
Population dynamics of Perna perna in low shore mussel beds were investigated over a 15 month period at six sites along the south coast of South Africa, with particular reference to the effects of wave exposure. The degree of exposure was first quantitatively ascertained using the dissolution of cement blocks to measure average wave force and dynamometers to measure maximum wave force. The mean mass loss of the cement blocks was higher at Diaz Cross and Kwaai Hoek than at Mgwalana, Rufanes and Riet River. No data were available for Fish River. The mean maximum wave force encountered at Diaz Cross, Kwaai Hoek and Fish River was significantly higher (p
15 mm) were positively correlated with recruit densities (1-5 mm) for both shore types (p 15 mm) was significantly lower on exposed (mean of 3 348.m⁻²) than on sheltered shores (mean of 4 796.m⁻²) (p O.05). The effect of exposure on growth rate formed the focal point of this study and was determined using three different approaches. The first technique, mark-recapture, involved filing notches on the growing edges of mussels in the field. After 111 days, mussels were removed and the growth measured. The second approach used internal growth bands to measure growth rates, once the periodicity with which these bands were laid down was established. Thirdly, using Shepherd's length composition analysis (SLCA), growth rates were determined from length frequency distributions in 11 samples taken over 15 months. The general conclusion from all three approaches was that growth rate was twice as fast on the exposed shores as on the sheltered shores (p - Full Text:
- Date Issued: 1999
Removal of lead from solution by the non-viable biomass of the water fern Azolla filiculoides
- Authors: Sanyahumbi, Douglas
- Date: 1999
- Subjects: Azolla , Heavy metals -- Absorption and adsorption , Lead , Water -- Purification -- Biological treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3901 , http://hdl.handle.net/10962/d1003960 , Azolla , Heavy metals -- Absorption and adsorption , Lead , Water -- Purification -- Biological treatment
- Description: The removal of lead from aqueous solution and lead-acid battery manufacturing waste-water by the non-viable biomass of the water fern Azolla filiculoides was investigated in both batch and column reactors. The maximum lead uptake by the Azolla biomass at a pH value of approximately 5, was found to be 100 mg lead/g biomass from aqueous solution. Lead removal varied from 30% of the initial lead concentration at pH 1.5 to approximately 95% at pH values of 3.5 and 5.6. Lead removal from aqueous solution decreased to 30% of the initial lead concentration if the lead concentration was initially over 400 mg/l. At initial lead concentrations of less than 400 mg/l, percentage lead removal was found to be over 90% of the initial lead concentration. Lead removal remained at approximately 90% between 10°C and 50°C. Biomass concentration (4-8 mg/l) had little effect on lead removal. The presence of iron (Fe) and lead, copper (Cu) and lead or all three metal ions in solution at varying ratios to each other did not appear to have any significant effect on lead removal. Percentage lead, copper and iron removal from aqueous solution was 80-95, 45-50 and 65-75% respectively for the different multiple-metal solutions studied. No break-through points were observed for lead removal from aqueous solutions in column reactors, with initial lead concentrations of less than 100 mg/l at varying flow rates of 2, 5 and 10 ml/min. This suggested that flow rate, and therefore retention time, had little effect on percentage lead removal from aqueous solution, which was more that 95%, at low initial lead concentrations (less than 100 mg/l). At initial lead concentrations of 200 mg/l or more, an increase in flow rate, which equates to a decrease in column retention time, resulted in break-through points occurring earlier in the column run. Percentage lead removal values, from lead-acid battery efiluent in column systems, of over 95% were achieved. Desorption of approximately 30% and 40% of bound lead was achieved, with 0.5 M HNO₃ in a volume of 50 ml, from two lead-acid battery. Repeated adsorption and desorption of lead by the Azalia biomass over 10 cycles did not result in any decrease in the percentage lead removal from effluent, which strongly suggested that the Azalla biomass could be re-used a number of times without deterioration in its physical integrity, or lead removal capacity. No evidence of deterioration in the Azolla biomass's physical integrity after 10 successive adsorption and desorption procedures was observed using scanning electron microscopy. The Azolla filiculoides biomass was, therefore, found to be able to effectively remove lead from aqueous solution and lead-acid battery effluent repeatedly, with no observed reduction in it's uptake capacity or physical integrity.
- Full Text:
- Date Issued: 1999
- Authors: Sanyahumbi, Douglas
- Date: 1999
- Subjects: Azolla , Heavy metals -- Absorption and adsorption , Lead , Water -- Purification -- Biological treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3901 , http://hdl.handle.net/10962/d1003960 , Azolla , Heavy metals -- Absorption and adsorption , Lead , Water -- Purification -- Biological treatment
- Description: The removal of lead from aqueous solution and lead-acid battery manufacturing waste-water by the non-viable biomass of the water fern Azolla filiculoides was investigated in both batch and column reactors. The maximum lead uptake by the Azolla biomass at a pH value of approximately 5, was found to be 100 mg lead/g biomass from aqueous solution. Lead removal varied from 30% of the initial lead concentration at pH 1.5 to approximately 95% at pH values of 3.5 and 5.6. Lead removal from aqueous solution decreased to 30% of the initial lead concentration if the lead concentration was initially over 400 mg/l. At initial lead concentrations of less than 400 mg/l, percentage lead removal was found to be over 90% of the initial lead concentration. Lead removal remained at approximately 90% between 10°C and 50°C. Biomass concentration (4-8 mg/l) had little effect on lead removal. The presence of iron (Fe) and lead, copper (Cu) and lead or all three metal ions in solution at varying ratios to each other did not appear to have any significant effect on lead removal. Percentage lead, copper and iron removal from aqueous solution was 80-95, 45-50 and 65-75% respectively for the different multiple-metal solutions studied. No break-through points were observed for lead removal from aqueous solutions in column reactors, with initial lead concentrations of less than 100 mg/l at varying flow rates of 2, 5 and 10 ml/min. This suggested that flow rate, and therefore retention time, had little effect on percentage lead removal from aqueous solution, which was more that 95%, at low initial lead concentrations (less than 100 mg/l). At initial lead concentrations of 200 mg/l or more, an increase in flow rate, which equates to a decrease in column retention time, resulted in break-through points occurring earlier in the column run. Percentage lead removal values, from lead-acid battery efiluent in column systems, of over 95% were achieved. Desorption of approximately 30% and 40% of bound lead was achieved, with 0.5 M HNO₃ in a volume of 50 ml, from two lead-acid battery. Repeated adsorption and desorption of lead by the Azalia biomass over 10 cycles did not result in any decrease in the percentage lead removal from effluent, which strongly suggested that the Azalla biomass could be re-used a number of times without deterioration in its physical integrity, or lead removal capacity. No evidence of deterioration in the Azolla biomass's physical integrity after 10 successive adsorption and desorption procedures was observed using scanning electron microscopy. The Azolla filiculoides biomass was, therefore, found to be able to effectively remove lead from aqueous solution and lead-acid battery effluent repeatedly, with no observed reduction in it's uptake capacity or physical integrity.
- Full Text:
- Date Issued: 1999
Size-fractionated phytoplankton biomass and primary production in the Southern Ocean
- Authors: Balarin, Marianne G
- Date: 1999
- Subjects: Biomass -- Analysis , Phytoplankton , Atlantic Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5765 , http://hdl.handle.net/10962/d1005453 , Biomass -- Analysis , Phytoplankton , Atlantic Ocean
- Description: The factors controlling primary production in the Southern Ocean were investigated over two years during two cruises of the South African National Antarctic Program (SANAP). The first cruise was conducted to the region of the eastern Atlantic sector of the Southern Ocean during the collaborative Scandinavian/South African Antarctic expedition conducted in austral summer (DecemberIFebruary) 1997-1998. Production studies were conducted in the vicinity of the Marginal Ice Zone (MIZ), Interfrontal Zone (IFZ) and Antarctic Polar Front(APF). The second cruise was conducted during the Third Marion Island Oceanographic Survey (MIOS III) to the region of the Sub-Antarctic Prince Edward Islands in austral autumn (April/May) 1998. Size-fractionated production rates were estimated by 14C incorporation using standard JGOFS protocols. Oceanographic data from the first cruise suggest that the three regions can be divided into two distinct regimes. Stations occupied in the vicinity of the MIZ and the APF were characterised by a shallow mixed layer depth « 40m) while at the IFZ-stations, the mixed layer depth exceeded the 1% light depth. Microphytoplankton dominated integrated chlorophyll-a biomass in the MIZ (total chlorophyll a ranged between 15.4 and 41.3 mg Chi-a. m-2) and at the APF (range between 10.7 and 31.4 mg Chi-a. m-2) , comprising > 50% of total chlorophyll-a at all these stations. Xl Within the IFZ (2 stations), nanophytoplankton dominated total integrated Chl-a biomass (range between 5.6 and 8.8 mg Chi-a. m-2) comprising, on average, 36% of the total. Picophytoplankton comprised an average of 12% of the total Chl-a biomass (range between 3.1 and 5.9 mg Chi-a. m-2) in the MIZ, 36% in the IFZ (range between 6.4 and 7.8 mg Chl-a . m-2) and 20% in the vicinity of the APF (range between 6.8 and 10.6 mg Chi-a. m-2). Total integrated primary production ranged between 316 and 729 mg C . m-2. d-1 at stations occupied in the vicinity of the MIZ, and between 292 and 317 mg C . m·2• d-l within the IFZ. At stations occupied in the region of the APF, total integrated production ranged between 708 and 926 mg C . m-2• dol. The contribution of various size fractions to total productivity generally displayed the same pattern as integrated Chl-a biomass. Microphytoplankton formed the most important contributor to total production at stations occupied in the MIZ and at the APF. Within the IFZ, nanophytoplankton dominated total daily production. Nutrient data suggest that concentrations of macro nutrients within the upper water column were above the threshold where growth would be limited. Preliminary results showed that concentrations of iron (Fe) were highest in the southern region of the MIZ and in the vicinity of the APF. During the second cruise, conducted in the vicinity of the Sub-Antarctic Front (SAF) and in the upstream, inter-island and downstream regions of the Prince Edward Islands, there was evidence of fresh water run-off from the islands, (i.e. decreased salinities and increased concentrations of ammonia and nitrate). Oceanographic data collected at the various production stations indicated that the upper water column was well mixed throughout the survey. Total integrated biomass during the study ranged between 8.5 and 20.1 mg Chi-a. m-2• No distinct patterns in total Chl-a biomass were evident. Picophytoplankton dominated total biomass comprising> 45 % of total pigment at all stations. Nanophytoplankton were the second most important contributor to total integrated biomass. Generally xu microphytoplankton contributed < 10 % of total ChI-a. Total daily integrated production was highest (442.6 mg Chi-a. m-2) at the single station occupied in the vicinity of the SAF. Outside this region, total areal production was lower, ranging from 94.5 to 353.0 mg C . m-2. d-1. With the exception of the station occupied in the vicinity of the SAF, total productivity was dominated by nanophytoplankton, which comprised between 48 and 66% of the total. Concentrations of macronutrients did not appear to be limiting to phytoplankton growth. The absence of a phytoplankton bloom in the vicinity of the islands appears to have been related to water column stability, which was influenced by the prevailing oceanographic regime during the survey. Previous studies have shown that when the SAF lies in close proximity to the islands, advecting forces prevail, resulting in the islands functioning as a flow-through system. During this study, the SAF lay immediately north of the islands. As a consequence no water was trapped in the leeward side of the islands. The results of the two cruises suggest that phytoplankton production in the four systems investigated: the Marginal Ice Zone (MIZ), Antarctic Polar Front (APF), Inter Frontal Zone (IFZ) and Prince Edward Islands (PEl), was largely controlled by water column stability. It is probable that the availability of iron, particularly in the region of the MIZ and APF, may have further contributed to the elevated production recorded in these two regions.
- Full Text:
- Date Issued: 1999
- Authors: Balarin, Marianne G
- Date: 1999
- Subjects: Biomass -- Analysis , Phytoplankton , Atlantic Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5765 , http://hdl.handle.net/10962/d1005453 , Biomass -- Analysis , Phytoplankton , Atlantic Ocean
- Description: The factors controlling primary production in the Southern Ocean were investigated over two years during two cruises of the South African National Antarctic Program (SANAP). The first cruise was conducted to the region of the eastern Atlantic sector of the Southern Ocean during the collaborative Scandinavian/South African Antarctic expedition conducted in austral summer (DecemberIFebruary) 1997-1998. Production studies were conducted in the vicinity of the Marginal Ice Zone (MIZ), Interfrontal Zone (IFZ) and Antarctic Polar Front(APF). The second cruise was conducted during the Third Marion Island Oceanographic Survey (MIOS III) to the region of the Sub-Antarctic Prince Edward Islands in austral autumn (April/May) 1998. Size-fractionated production rates were estimated by 14C incorporation using standard JGOFS protocols. Oceanographic data from the first cruise suggest that the three regions can be divided into two distinct regimes. Stations occupied in the vicinity of the MIZ and the APF were characterised by a shallow mixed layer depth « 40m) while at the IFZ-stations, the mixed layer depth exceeded the 1% light depth. Microphytoplankton dominated integrated chlorophyll-a biomass in the MIZ (total chlorophyll a ranged between 15.4 and 41.3 mg Chi-a. m-2) and at the APF (range between 10.7 and 31.4 mg Chi-a. m-2) , comprising > 50% of total chlorophyll-a at all these stations. Xl Within the IFZ (2 stations), nanophytoplankton dominated total integrated Chl-a biomass (range between 5.6 and 8.8 mg Chi-a. m-2) comprising, on average, 36% of the total. Picophytoplankton comprised an average of 12% of the total Chl-a biomass (range between 3.1 and 5.9 mg Chi-a. m-2) in the MIZ, 36% in the IFZ (range between 6.4 and 7.8 mg Chl-a . m-2) and 20% in the vicinity of the APF (range between 6.8 and 10.6 mg Chi-a. m-2). Total integrated primary production ranged between 316 and 729 mg C . m-2. d-1 at stations occupied in the vicinity of the MIZ, and between 292 and 317 mg C . m·2• d-l within the IFZ. At stations occupied in the region of the APF, total integrated production ranged between 708 and 926 mg C . m-2• dol. The contribution of various size fractions to total productivity generally displayed the same pattern as integrated Chl-a biomass. Microphytoplankton formed the most important contributor to total production at stations occupied in the MIZ and at the APF. Within the IFZ, nanophytoplankton dominated total daily production. Nutrient data suggest that concentrations of macro nutrients within the upper water column were above the threshold where growth would be limited. Preliminary results showed that concentrations of iron (Fe) were highest in the southern region of the MIZ and in the vicinity of the APF. During the second cruise, conducted in the vicinity of the Sub-Antarctic Front (SAF) and in the upstream, inter-island and downstream regions of the Prince Edward Islands, there was evidence of fresh water run-off from the islands, (i.e. decreased salinities and increased concentrations of ammonia and nitrate). Oceanographic data collected at the various production stations indicated that the upper water column was well mixed throughout the survey. Total integrated biomass during the study ranged between 8.5 and 20.1 mg Chi-a. m-2• No distinct patterns in total Chl-a biomass were evident. Picophytoplankton dominated total biomass comprising> 45 % of total pigment at all stations. Nanophytoplankton were the second most important contributor to total integrated biomass. Generally xu microphytoplankton contributed < 10 % of total ChI-a. Total daily integrated production was highest (442.6 mg Chi-a. m-2) at the single station occupied in the vicinity of the SAF. Outside this region, total areal production was lower, ranging from 94.5 to 353.0 mg C . m-2. d-1. With the exception of the station occupied in the vicinity of the SAF, total productivity was dominated by nanophytoplankton, which comprised between 48 and 66% of the total. Concentrations of macronutrients did not appear to be limiting to phytoplankton growth. The absence of a phytoplankton bloom in the vicinity of the islands appears to have been related to water column stability, which was influenced by the prevailing oceanographic regime during the survey. Previous studies have shown that when the SAF lies in close proximity to the islands, advecting forces prevail, resulting in the islands functioning as a flow-through system. During this study, the SAF lay immediately north of the islands. As a consequence no water was trapped in the leeward side of the islands. The results of the two cruises suggest that phytoplankton production in the four systems investigated: the Marginal Ice Zone (MIZ), Antarctic Polar Front (APF), Inter Frontal Zone (IFZ) and Prince Edward Islands (PEl), was largely controlled by water column stability. It is probable that the availability of iron, particularly in the region of the MIZ and APF, may have further contributed to the elevated production recorded in these two regions.
- Full Text:
- Date Issued: 1999
Studies on captive rearing of spotted grunter, pommadasys commersonnii (Pisces : Haemulidae) under ambient conditions
- Authors: Bacela, Ntobeko
- Date: 1999
- Subjects: Grunts (Fishes)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5322 , http://hdl.handle.net/10962/d1005167 , Grunts (Fishes)
- Description: The effects of stocking density, size grading, feeding frequency and ambient temperature on the growth performance and size variation of spotted grunter, Pomadasys commersonnii were investigated. The time that would be required to rear the species to market size was modelled. An area where maximum growth rate could be achieved under ambient temperature conditions, and therefore the location of a commercial farm within the distribution range of spotted grunter along the coast of South Africa, was predicted. The growth performance of spotted grunter was not significantly affected by stocking density. Growth performance seemed to improve with increasing stocking density. Competitive behaviour was absent among fish in the various stocking densities. Growth in terms of fork length and body weight was not significantly different between stocking densities. The highest specific growth rate, best food consumption, food conversion ratio and protein efficiency ratio of the fish were recorded at a density of 6.4 kg/m³, whereas the best condition factor was recorded at a density of 3.8 kg/m³. The lack of significant difference in many of the growth parameters between the various stocking densities suggest that juvenile spotted grunter could be reared at densities higher than 6.4 kg/m³. Further investigations are needed to determine the optimal initial stocking density of juvenile spotted grunter under ambient temperature and photoperiod conditions. Replacing the largest fish with average sized fish did not have a significant effect on the specific growth rate and competitive behaviour based on the relationship between the coefficient of variation and average size. Feeding frequency had a sIgnificant effect on food consumption, food conversion and protein efficiency ratio, and not on size increase, specific growth rate and condition factor. Its effect on competitive behaviour could not be conclusively explained. The best food conversion ratio recorded when feeding once a day showed that although the fish consumed a limited amount of food, they utilised the food that was fed most effectively. It is suggested that the fish be fed three times a day. The survival of juvenile spotted grunter was 95.6 % when feeding three times a day compared to 90 and 90.2 % when feeding once and five times a day, respectively. Fluctuating ambient temperature had a dramatic effect on specific growth rate and food consumption of spotted grunter. Growth modelling showed that the fish could be reared to a market size of 550 g (270 mm FL) in 19 months under ambient temperature conditions (23.2°C) at Richard's Bay. The optimal predicted rearing period of 19 months is approximately seven months less than that calculated for fish in the wild, and can possibly, be reduced further by feeding a balanced diet. The overall food consumption (on a dry weight basis) in the three size classes ranged from 0.15 ± 0.16 to 0.38 ± 0.35 % body weight per day. Food conversion ratio improved with increasing fish size. This relationship was attributed to diet quality and more specifically, the protein : energy ratio. As a result, fish in the large size class had the best overall protein efficiency ratio. Maximum specific growth rates of1.5, 0.84 and 0.74 % body weight per day were recorded from the small, medium and large size classes in the peak of summer with average daily temperature ranging from 21 to 22°C. Positive slopes in the coefficient of variation against fish size in the large size class indicated the presence of competitive behaviour which was attributed to the onset of adolescence. The information from this study can be used for pilot production of spotted grunter. Further research should be undertaken to investigate captive reproduction of the species.
- Full Text:
- Date Issued: 1999
- Authors: Bacela, Ntobeko
- Date: 1999
- Subjects: Grunts (Fishes)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5322 , http://hdl.handle.net/10962/d1005167 , Grunts (Fishes)
- Description: The effects of stocking density, size grading, feeding frequency and ambient temperature on the growth performance and size variation of spotted grunter, Pomadasys commersonnii were investigated. The time that would be required to rear the species to market size was modelled. An area where maximum growth rate could be achieved under ambient temperature conditions, and therefore the location of a commercial farm within the distribution range of spotted grunter along the coast of South Africa, was predicted. The growth performance of spotted grunter was not significantly affected by stocking density. Growth performance seemed to improve with increasing stocking density. Competitive behaviour was absent among fish in the various stocking densities. Growth in terms of fork length and body weight was not significantly different between stocking densities. The highest specific growth rate, best food consumption, food conversion ratio and protein efficiency ratio of the fish were recorded at a density of 6.4 kg/m³, whereas the best condition factor was recorded at a density of 3.8 kg/m³. The lack of significant difference in many of the growth parameters between the various stocking densities suggest that juvenile spotted grunter could be reared at densities higher than 6.4 kg/m³. Further investigations are needed to determine the optimal initial stocking density of juvenile spotted grunter under ambient temperature and photoperiod conditions. Replacing the largest fish with average sized fish did not have a significant effect on the specific growth rate and competitive behaviour based on the relationship between the coefficient of variation and average size. Feeding frequency had a sIgnificant effect on food consumption, food conversion and protein efficiency ratio, and not on size increase, specific growth rate and condition factor. Its effect on competitive behaviour could not be conclusively explained. The best food conversion ratio recorded when feeding once a day showed that although the fish consumed a limited amount of food, they utilised the food that was fed most effectively. It is suggested that the fish be fed three times a day. The survival of juvenile spotted grunter was 95.6 % when feeding three times a day compared to 90 and 90.2 % when feeding once and five times a day, respectively. Fluctuating ambient temperature had a dramatic effect on specific growth rate and food consumption of spotted grunter. Growth modelling showed that the fish could be reared to a market size of 550 g (270 mm FL) in 19 months under ambient temperature conditions (23.2°C) at Richard's Bay. The optimal predicted rearing period of 19 months is approximately seven months less than that calculated for fish in the wild, and can possibly, be reduced further by feeding a balanced diet. The overall food consumption (on a dry weight basis) in the three size classes ranged from 0.15 ± 0.16 to 0.38 ± 0.35 % body weight per day. Food conversion ratio improved with increasing fish size. This relationship was attributed to diet quality and more specifically, the protein : energy ratio. As a result, fish in the large size class had the best overall protein efficiency ratio. Maximum specific growth rates of1.5, 0.84 and 0.74 % body weight per day were recorded from the small, medium and large size classes in the peak of summer with average daily temperature ranging from 21 to 22°C. Positive slopes in the coefficient of variation against fish size in the large size class indicated the presence of competitive behaviour which was attributed to the onset of adolescence. The information from this study can be used for pilot production of spotted grunter. Further research should be undertaken to investigate captive reproduction of the species.
- Full Text:
- Date Issued: 1999
Sulphate reduction utilizing hydrolysis of complex carbon sources
- Authors: Molipane, Ntaoleng Patricia
- Date: 1999
- Subjects: Sewage sludge , Acid mine drainage , Hydrolysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4000 , http://hdl.handle.net/10962/d1004060 , Sewage sludge , Acid mine drainage , Hydrolysis
- Description: Due to environmental pollution caused by acid mine drainage (AMD), the Department of Water Affairs has developed a National Water Bill for managing and controlling the water environment to prevent AMD pollution. The application of sulphate reducing bacteria have been demonstrated for the treatment of AMD. However, the scale-up application of this technology ultimately depends on the cost and availability of a carbon source. This study evaluated the use of sewage sludge to provide a carbon source for sulphate reduction in synthetic drainage wastewaters. The demonstration of this process in a laboratory-scale reactor proved that sewage sludge could provide a useful model and viable carbon source for evaluation of sulphate reduction as a process for treating AMD. Since sewage sludge is a complex carbon source, hydrolysis reactions controlling the anaerobic digestion of particulate substrate from this medium were optimized by evaluating the effect of pH on hydrolysis. Controlled and uncontrolled pH studies were conducted using a three stage mixed anaerobic reactor. Analysis of the degradation behaviour of the three important organic classes (carbohydrate, proteins and lipids) revealed that each class followed an indvidual trend with respect to pH changes. In addition, the solubilization of organic particulate carbon was also shown to be a function of pH. The hydrolysis pattern of organic substrate and COD solublization was induced at pH 6.5 rather than at high pH values (7.5 and 8.5). The biodegradation activity of sewage sludge was characterized by the API-ZYM1N test system to provide rapid semiquantitative information on the activity of hydrolytic enzymes associated with the degradation of carbohydrates, lipids, proteins and nucleic acids. A wide range of enzyme activities with phosphatases, aminopeptidases, and glucosyl hydralases dominating were displayed. The pattern of substrate hydrolysis correlated to the degradation efficiency of each organic class as a function of pH. The evaluation of scale-up application for sulphate reduction utilizing sewage sludge as a carbon source demonstrated that large water volume flows could possibly be treated with this cost-effective technology. Generation of alkalinity and sulphide in this medium was shown to be successful in the removal of heavy metals by precipitation. The use of this technology coupled to reduced cost involved showed that biological sulphate reduction utilizing hydrolysates of complex organic particulate from sewage sludge ss a carbon source has a potential scale-up application for the treatment of AMD.
- Full Text:
- Date Issued: 1999
- Authors: Molipane, Ntaoleng Patricia
- Date: 1999
- Subjects: Sewage sludge , Acid mine drainage , Hydrolysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4000 , http://hdl.handle.net/10962/d1004060 , Sewage sludge , Acid mine drainage , Hydrolysis
- Description: Due to environmental pollution caused by acid mine drainage (AMD), the Department of Water Affairs has developed a National Water Bill for managing and controlling the water environment to prevent AMD pollution. The application of sulphate reducing bacteria have been demonstrated for the treatment of AMD. However, the scale-up application of this technology ultimately depends on the cost and availability of a carbon source. This study evaluated the use of sewage sludge to provide a carbon source for sulphate reduction in synthetic drainage wastewaters. The demonstration of this process in a laboratory-scale reactor proved that sewage sludge could provide a useful model and viable carbon source for evaluation of sulphate reduction as a process for treating AMD. Since sewage sludge is a complex carbon source, hydrolysis reactions controlling the anaerobic digestion of particulate substrate from this medium were optimized by evaluating the effect of pH on hydrolysis. Controlled and uncontrolled pH studies were conducted using a three stage mixed anaerobic reactor. Analysis of the degradation behaviour of the three important organic classes (carbohydrate, proteins and lipids) revealed that each class followed an indvidual trend with respect to pH changes. In addition, the solubilization of organic particulate carbon was also shown to be a function of pH. The hydrolysis pattern of organic substrate and COD solublization was induced at pH 6.5 rather than at high pH values (7.5 and 8.5). The biodegradation activity of sewage sludge was characterized by the API-ZYM1N test system to provide rapid semiquantitative information on the activity of hydrolytic enzymes associated with the degradation of carbohydrates, lipids, proteins and nucleic acids. A wide range of enzyme activities with phosphatases, aminopeptidases, and glucosyl hydralases dominating were displayed. The pattern of substrate hydrolysis correlated to the degradation efficiency of each organic class as a function of pH. The evaluation of scale-up application for sulphate reduction utilizing sewage sludge as a carbon source demonstrated that large water volume flows could possibly be treated with this cost-effective technology. Generation of alkalinity and sulphide in this medium was shown to be successful in the removal of heavy metals by precipitation. The use of this technology coupled to reduced cost involved showed that biological sulphate reduction utilizing hydrolysates of complex organic particulate from sewage sludge ss a carbon source has a potential scale-up application for the treatment of AMD.
- Full Text:
- Date Issued: 1999