An investigation of issues of privacy, anonymity and multi-factor authentication in an open environment
- Authors: Miles, Shaun Graeme
- Date: 2012-06-20
- Subjects: Electronic data processing departments -- Security measures , Electronic data processing departments , Privacy, Right of , Computer security , Data protection , Computers -- Access control
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4656 , http://hdl.handle.net/10962/d1006653 , Electronic data processing departments -- Security measures , Electronic data processing departments , Privacy, Right of , Computer security , Data protection , Computers -- Access control
- Description: This thesis performs an investigation into issues concerning the broad area ofIdentity and Access Management, with a focus on open environments. Through literature research the issues of privacy, anonymity and access control are identified. The issue of privacy is an inherent problem due to the nature of the digital network environment. Information can be duplicated and modified regardless of the wishes and intentions ofthe owner of that information unless proper measures are taken to secure the environment. Once information is published or divulged on the network, there is very little way of controlling the subsequent usage of that information. To address this issue a model for privacy is presented that follows the user centric paradigm of meta-identity. The lack of anonymity, where security measures can be thwarted through the observation of the environment, is a concern for users and systems. By an attacker observing the communication channel and monitoring the interactions between users and systems over a long enough period of time, it is possible to infer knowledge about the users and systems. This knowledge is used to build an identity profile of potential victims to be used in subsequent attacks. To address the problem, mechanisms for providing an acceptable level of anonymity while maintaining adequate accountability (from a legal standpoint) are explored. In terms of access control, the inherent weakness of single factor authentication mechanisms is discussed. The typical mechanism is the user-name and password pair, which provides a single point of failure. By increasing the factors used in authentication, the amount of work required to compromise the system increases non-linearly. Within an open network, several aspects hinder wide scale adoption and use of multi-factor authentication schemes, such as token management and the impact on usability. The framework is developed from a Utopian point of view, with the aim of being applicable to many situations as opposed to a single specific domain. The framework incorporates multi-factor authentication over multiple paths using mobile phones and GSM networks, and explores the usefulness of such an approach. The models are in tum analysed, providing a discussion into the assumptions made and the problems faced by each model. , Adobe Acrobat Pro 9.5.1 , Adobe Acrobat 9.51 Paper Capture Plug-in
- Full Text:
- Authors: Miles, Shaun Graeme
- Date: 2012-06-20
- Subjects: Electronic data processing departments -- Security measures , Electronic data processing departments , Privacy, Right of , Computer security , Data protection , Computers -- Access control
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4656 , http://hdl.handle.net/10962/d1006653 , Electronic data processing departments -- Security measures , Electronic data processing departments , Privacy, Right of , Computer security , Data protection , Computers -- Access control
- Description: This thesis performs an investigation into issues concerning the broad area ofIdentity and Access Management, with a focus on open environments. Through literature research the issues of privacy, anonymity and access control are identified. The issue of privacy is an inherent problem due to the nature of the digital network environment. Information can be duplicated and modified regardless of the wishes and intentions ofthe owner of that information unless proper measures are taken to secure the environment. Once information is published or divulged on the network, there is very little way of controlling the subsequent usage of that information. To address this issue a model for privacy is presented that follows the user centric paradigm of meta-identity. The lack of anonymity, where security measures can be thwarted through the observation of the environment, is a concern for users and systems. By an attacker observing the communication channel and monitoring the interactions between users and systems over a long enough period of time, it is possible to infer knowledge about the users and systems. This knowledge is used to build an identity profile of potential victims to be used in subsequent attacks. To address the problem, mechanisms for providing an acceptable level of anonymity while maintaining adequate accountability (from a legal standpoint) are explored. In terms of access control, the inherent weakness of single factor authentication mechanisms is discussed. The typical mechanism is the user-name and password pair, which provides a single point of failure. By increasing the factors used in authentication, the amount of work required to compromise the system increases non-linearly. Within an open network, several aspects hinder wide scale adoption and use of multi-factor authentication schemes, such as token management and the impact on usability. The framework is developed from a Utopian point of view, with the aim of being applicable to many situations as opposed to a single specific domain. The framework incorporates multi-factor authentication over multiple paths using mobile phones and GSM networks, and explores the usefulness of such an approach. The models are in tum analysed, providing a discussion into the assumptions made and the problems faced by each model. , Adobe Acrobat Pro 9.5.1 , Adobe Acrobat 9.51 Paper Capture Plug-in
- Full Text:
A common analysis framework for simulated streaming-video networks
- Authors: Mulumba, Patrick
- Date: 2009
- Subjects: Computer networks -- Management , Streaming video , Mass media -- Technological innovations
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4590 , http://hdl.handle.net/10962/d1004828 , Computer networks -- Management , Streaming video , Mass media -- Technological innovations
- Description: Distributed media streaming has been driven by the combination of improved media compression techniques and an increase in the availability of bandwidth. This increase has lead to the development of various streaming distribution engines (systems/services), which currently provide the majority of the streaming media available throughout the Internet. This study aimed to analyse a range of existing commercial and open-source streaming media distribution engines, and classify them in such a way as to define a Common Analysis Framework for Simulated Streaming-Video Networks (CAFSS-Net). This common framework was used as the basis for a simulation tool intended to aid in the development and deployment of streaming media networks and predict the performance impacts of both network configuration changes, video features (scene complexity, resolution) and general scaling. CAFSS-Net consists of six components: the server, the client(s), the network simulator, the video publishing tools, the videos and the evaluation tool-set. Test scenarios are presented consisting of different network configurations, scales and external traffic specifications. From these test scenarios, results were obtained to determine interesting observations attained and to provide an overview of the different test specications for this study. From these results, an analysis of the system was performed, yielding relationships between the videos, the different bandwidths, the different measurement tools and the different components of CAFSS-Net. Based on the analysis of the results, the implications for CAFSS-Net highlighted different achievements and proposals for future work for the different components. CAFSS-Net was able to successfully integrate all of its components to evaluate the different streaming scenarios. The streaming server, client and video components accomplished their objectives. It is noted that although the video publishing tool was able to provide the necessary compression/decompression services, proposals for the implementation of alternative compression/decompression schemes could serve as a suitable extension. The network simulator and evaluation tool-set components were also successful, but future tests (particularly in low bandwidth scenarios) are suggested in order to further improve the accuracy of the framework as a whole. CAFSS-Net is especially successful with analysing high bandwidth connections with the results being similar to those of the physical network tests.
- Full Text:
- Date Issued: 2009
- Authors: Mulumba, Patrick
- Date: 2009
- Subjects: Computer networks -- Management , Streaming video , Mass media -- Technological innovations
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4590 , http://hdl.handle.net/10962/d1004828 , Computer networks -- Management , Streaming video , Mass media -- Technological innovations
- Description: Distributed media streaming has been driven by the combination of improved media compression techniques and an increase in the availability of bandwidth. This increase has lead to the development of various streaming distribution engines (systems/services), which currently provide the majority of the streaming media available throughout the Internet. This study aimed to analyse a range of existing commercial and open-source streaming media distribution engines, and classify them in such a way as to define a Common Analysis Framework for Simulated Streaming-Video Networks (CAFSS-Net). This common framework was used as the basis for a simulation tool intended to aid in the development and deployment of streaming media networks and predict the performance impacts of both network configuration changes, video features (scene complexity, resolution) and general scaling. CAFSS-Net consists of six components: the server, the client(s), the network simulator, the video publishing tools, the videos and the evaluation tool-set. Test scenarios are presented consisting of different network configurations, scales and external traffic specifications. From these test scenarios, results were obtained to determine interesting observations attained and to provide an overview of the different test specications for this study. From these results, an analysis of the system was performed, yielding relationships between the videos, the different bandwidths, the different measurement tools and the different components of CAFSS-Net. Based on the analysis of the results, the implications for CAFSS-Net highlighted different achievements and proposals for future work for the different components. CAFSS-Net was able to successfully integrate all of its components to evaluate the different streaming scenarios. The streaming server, client and video components accomplished their objectives. It is noted that although the video publishing tool was able to provide the necessary compression/decompression services, proposals for the implementation of alternative compression/decompression schemes could serve as a suitable extension. The network simulator and evaluation tool-set components were also successful, but future tests (particularly in low bandwidth scenarios) are suggested in order to further improve the accuracy of the framework as a whole. CAFSS-Net is especially successful with analysing high bandwidth connections with the results being similar to those of the physical network tests.
- Full Text:
- Date Issued: 2009
A feasibility study into the possibility of ionospheric propagation of low VHF (30-35 MHZ) signals between South Africa and Central Africa
- Authors: Coetzee, Petrus Johannes
- Date: 2009
- Subjects: Communications, Military -- South Africa , Communications, Military -- Africa, Central , Digital communications -- South Africa , Digital communications -- Africa, Central , Signals and signaling -- South Africa , Signals and signaling -- Africa, Central , Artificial satellites in telecommunication -- South Africa , Artificial satellites in telecommunication -- Africa, Central , Shortwave radio
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5465 , http://hdl.handle.net/10962/d1005250 , Communications, Military -- South Africa , Communications, Military -- Africa, Central , Digital communications -- South Africa , Digital communications -- Africa, Central , Signals and signaling -- South Africa , Signals and signaling -- Africa, Central , Artificial satellites in telecommunication -- South Africa , Artificial satellites in telecommunication -- Africa, Central , Shortwave radio
- Description: The role of the South African National Defence Force (SANDF) has changed considerably in the last decade. The emphasis has moved from protecting the country's borders to peacekeeping duties in Central Africa and even further North. Communications between the peacekeeping missions and the military bases back in South Africa is vital to ensure the success of these missions. Currently use is made of satellite as well as High Frequency (HF) communications. There are drawbacks associated with these technologies (high cost and low data rates/interference respectively). Successful long distance ionospheric propagation in the low Very High Frequency (VHF) range will complement the existing infrastructure and enhance the success rate of these missions. This thesis presents a feasibility study to determine under what ionospheric conditions such low VHF communications will be possible. The International Reference Ionosphere (IRI) was used to generate ionospheric data for the reflection point(s) of the signal. The peak height of the ionospheric F2 layer (hmF2) was used to calculate the required antenna elevation angle. Once the elevation angle is known it is possible to calculate the required F2 layer critical frequency (foF2). The required foF2 value was calculated by assuming a Maximum Useable Frequency (MUF) of 20% higher than the planned operational frequency. It was determined that single hop propagation is possible during the daytime if the smoothed sunspot number (SSN) exceeds 15. The most challenging requirement for successful single hop propagation is the need of an antenna height of 23 m. For rapid deployment and semi-mobile operations within a jungle environment it may prove to be a formidable obstacle.
- Full Text:
- Date Issued: 2009
- Authors: Coetzee, Petrus Johannes
- Date: 2009
- Subjects: Communications, Military -- South Africa , Communications, Military -- Africa, Central , Digital communications -- South Africa , Digital communications -- Africa, Central , Signals and signaling -- South Africa , Signals and signaling -- Africa, Central , Artificial satellites in telecommunication -- South Africa , Artificial satellites in telecommunication -- Africa, Central , Shortwave radio
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5465 , http://hdl.handle.net/10962/d1005250 , Communications, Military -- South Africa , Communications, Military -- Africa, Central , Digital communications -- South Africa , Digital communications -- Africa, Central , Signals and signaling -- South Africa , Signals and signaling -- Africa, Central , Artificial satellites in telecommunication -- South Africa , Artificial satellites in telecommunication -- Africa, Central , Shortwave radio
- Description: The role of the South African National Defence Force (SANDF) has changed considerably in the last decade. The emphasis has moved from protecting the country's borders to peacekeeping duties in Central Africa and even further North. Communications between the peacekeeping missions and the military bases back in South Africa is vital to ensure the success of these missions. Currently use is made of satellite as well as High Frequency (HF) communications. There are drawbacks associated with these technologies (high cost and low data rates/interference respectively). Successful long distance ionospheric propagation in the low Very High Frequency (VHF) range will complement the existing infrastructure and enhance the success rate of these missions. This thesis presents a feasibility study to determine under what ionospheric conditions such low VHF communications will be possible. The International Reference Ionosphere (IRI) was used to generate ionospheric data for the reflection point(s) of the signal. The peak height of the ionospheric F2 layer (hmF2) was used to calculate the required antenna elevation angle. Once the elevation angle is known it is possible to calculate the required F2 layer critical frequency (foF2). The required foF2 value was calculated by assuming a Maximum Useable Frequency (MUF) of 20% higher than the planned operational frequency. It was determined that single hop propagation is possible during the daytime if the smoothed sunspot number (SSN) exceeds 15. The most challenging requirement for successful single hop propagation is the need of an antenna height of 23 m. For rapid deployment and semi-mobile operations within a jungle environment it may prove to be a formidable obstacle.
- Full Text:
- Date Issued: 2009
A fluvial geomorphological study of river rehabilitation in the Kouga region, Eastern Cape
- Authors: Pietersen, Adrian
- Date: 2009
- Subjects: Fluvial geomorphology -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Kouga Riparian Rehabilitation Project , Stream conservation -- South Africa -- Eastern Cape , Wattles (Plants) -- South Africa -- Eastern Cape , Riparian restoration -- South Africa -- Eastern Cape , Acacia mearnsii -- South Africa -- Eastern Cape , Kouga Region (South Africa) , Kouga River (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4887 , http://hdl.handle.net/10962/d1015228
- Description: The Kouga Riparian Rehabilitation Project (KRRP) is seen as a pilot rehabilitation project in the Kouga region that is heavily invaded with Acacia mearnsii along the riparian zones of many mountain streams. Clearing of these black wattles and re-planting of indigenous vegetation are imperative to rehabilitation efforts. In this context, two invaded catchments were identified - the Baviaans and the Heuningnes. The aim of this research is to characterise the effects that the woody alien invasive Acacia mearnsii has had on the river channel morphology of the Baviaans and Heuningnes Rivers. A desktop and initial field analysis of the relevant study area catchments was completed. This was followed by a comparison of the channel morphology of the various study channel reaches using fixed channel transects. Ecological resource quality objectives (RQOs) for river rehabilitation from a fluvial geomorphological viewpoint were then established. A long-term monitoring protocol to assess whether or not these RQOs will be achieved was recommended. Follow-up channel transects were measured post wattle clearance in the Baviaans and short-term (<2yrs) changes in channel form were described. Differences in terms of the effect of Acacia mearnsii on channel form were then interpreted by direct comparison and through statistical analysis. Results indicate a number of significant differences between those channels impacted by black wattle infestation and those channels seen as unimpacted and natural. Short-term changes (<2yrs) that occurred within the study period post Baviaans wattle clearance were shown to be minimal for channel form as well as for bed material. The lack of any clear relationship or explanation between channel form and other channel controls suggests vegetation as the primary control. Vegetation, specifically the invasive alien vegetation, is the key controlling variable acting on channel form in the two study catchments.
- Full Text:
- Date Issued: 2009
- Authors: Pietersen, Adrian
- Date: 2009
- Subjects: Fluvial geomorphology -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Kouga Riparian Rehabilitation Project , Stream conservation -- South Africa -- Eastern Cape , Wattles (Plants) -- South Africa -- Eastern Cape , Riparian restoration -- South Africa -- Eastern Cape , Acacia mearnsii -- South Africa -- Eastern Cape , Kouga Region (South Africa) , Kouga River (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4887 , http://hdl.handle.net/10962/d1015228
- Description: The Kouga Riparian Rehabilitation Project (KRRP) is seen as a pilot rehabilitation project in the Kouga region that is heavily invaded with Acacia mearnsii along the riparian zones of many mountain streams. Clearing of these black wattles and re-planting of indigenous vegetation are imperative to rehabilitation efforts. In this context, two invaded catchments were identified - the Baviaans and the Heuningnes. The aim of this research is to characterise the effects that the woody alien invasive Acacia mearnsii has had on the river channel morphology of the Baviaans and Heuningnes Rivers. A desktop and initial field analysis of the relevant study area catchments was completed. This was followed by a comparison of the channel morphology of the various study channel reaches using fixed channel transects. Ecological resource quality objectives (RQOs) for river rehabilitation from a fluvial geomorphological viewpoint were then established. A long-term monitoring protocol to assess whether or not these RQOs will be achieved was recommended. Follow-up channel transects were measured post wattle clearance in the Baviaans and short-term (<2yrs) changes in channel form were described. Differences in terms of the effect of Acacia mearnsii on channel form were then interpreted by direct comparison and through statistical analysis. Results indicate a number of significant differences between those channels impacted by black wattle infestation and those channels seen as unimpacted and natural. Short-term changes (<2yrs) that occurred within the study period post Baviaans wattle clearance were shown to be minimal for channel form as well as for bed material. The lack of any clear relationship or explanation between channel form and other channel controls suggests vegetation as the primary control. Vegetation, specifically the invasive alien vegetation, is the key controlling variable acting on channel form in the two study catchments.
- Full Text:
- Date Issued: 2009
A GIS assessment of development and land use change in the coastal zone of the Ndlambe and Ngqushwa local municipalities, Eastern Cape, South Africa
- Authors: Palmer, Bronwyn Jane
- Date: 2009
- Subjects: Ndlambe Municipality , Ngqushwa Municipality , Local government -- South Africa -- Eastern Cape , Coastal zone management -- South Africa -- Eastern Cape , Geographic information systems -- South Africa -- Eastern Cape , Land use -- South Africa -- Eastern Cape , Rural development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4836 , http://hdl.handle.net/10962/d1005511 , Ndlambe Municipality , Ngqushwa Municipality , Local government -- South Africa -- Eastern Cape , Coastal zone management -- South Africa -- Eastern Cape , Geographic information systems -- South Africa -- Eastern Cape , Land use -- South Africa -- Eastern Cape , Rural development -- South Africa -- Eastern Cape
- Description: The coastal zone accommodates some of the most diverse ecosystems in the world and offers a wide range of ecosystem goods and services; consequently it has become a focal point of human development. People are attracted to the coast because of access to resources, favourable climate, aesthetic appeal and potential for recreational activities. As pressure for utilisation and development increases, so does the need to manage the coastal system more effectively. This research focuses on the coastal zone of the Ndlambe and Ngqushwa local municipalities in the Eastern Cape, South Africa, which are physically and environmentally similar, yet have distinct demographic and socio-economic differences. The research integrates information using GIS, from three time epochs, to determine where development and land use change is occurring. The Ndlambe Local Municipality displays high levels of formal development, while the Ngqushwa Local Municipality exhibits little formal development. These differences in development and land use are related to economic, social and legislative ‘drivers’ based on an adapted Driver-Pressure-State- Impact-Response model. The model identifies that development and land use changes lead to increased pressure on the natural system, which in turn leads to shifts in the natural state of the coastal zone, resulting in adverse impacts on the coastal zone. Changes in the natural functioning of the coastal zone highlight the need for a response in terms of changes in legislation governing coastal management and spatial planning. This research concludes that pressure for development in the coastal zone within the research site is beginning to increase and will adversely affect the coastal zone if not managed effectively. These two local municipalities have the opportunity to move forward and develop in such a way that allows for conservation and sound management of the coastal zone, which will ensure long-term sustainability within the coastal zones of the Ndlambe and Ngqushwa local municipalities
- Full Text:
- Date Issued: 2009
- Authors: Palmer, Bronwyn Jane
- Date: 2009
- Subjects: Ndlambe Municipality , Ngqushwa Municipality , Local government -- South Africa -- Eastern Cape , Coastal zone management -- South Africa -- Eastern Cape , Geographic information systems -- South Africa -- Eastern Cape , Land use -- South Africa -- Eastern Cape , Rural development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4836 , http://hdl.handle.net/10962/d1005511 , Ndlambe Municipality , Ngqushwa Municipality , Local government -- South Africa -- Eastern Cape , Coastal zone management -- South Africa -- Eastern Cape , Geographic information systems -- South Africa -- Eastern Cape , Land use -- South Africa -- Eastern Cape , Rural development -- South Africa -- Eastern Cape
- Description: The coastal zone accommodates some of the most diverse ecosystems in the world and offers a wide range of ecosystem goods and services; consequently it has become a focal point of human development. People are attracted to the coast because of access to resources, favourable climate, aesthetic appeal and potential for recreational activities. As pressure for utilisation and development increases, so does the need to manage the coastal system more effectively. This research focuses on the coastal zone of the Ndlambe and Ngqushwa local municipalities in the Eastern Cape, South Africa, which are physically and environmentally similar, yet have distinct demographic and socio-economic differences. The research integrates information using GIS, from three time epochs, to determine where development and land use change is occurring. The Ndlambe Local Municipality displays high levels of formal development, while the Ngqushwa Local Municipality exhibits little formal development. These differences in development and land use are related to economic, social and legislative ‘drivers’ based on an adapted Driver-Pressure-State- Impact-Response model. The model identifies that development and land use changes lead to increased pressure on the natural system, which in turn leads to shifts in the natural state of the coastal zone, resulting in adverse impacts on the coastal zone. Changes in the natural functioning of the coastal zone highlight the need for a response in terms of changes in legislation governing coastal management and spatial planning. This research concludes that pressure for development in the coastal zone within the research site is beginning to increase and will adversely affect the coastal zone if not managed effectively. These two local municipalities have the opportunity to move forward and develop in such a way that allows for conservation and sound management of the coastal zone, which will ensure long-term sustainability within the coastal zones of the Ndlambe and Ngqushwa local municipalities
- Full Text:
- Date Issued: 2009
A grid based approach for the control and recall of the properties of IEEE 1394 audio devices
- Authors: Foulkes, Philip James
- Date: 2009
- Subjects: IEEE 1394 (Standard) , Computer sound processing , Digital communications , Local area networks (Computer networks) , Sound -- Recording and reproducing -- Digital techniques , Computational grids (Computer systems)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4594 , http://hdl.handle.net/10962/d1004836 , IEEE 1394 (Standard) , Computer sound processing , Digital communications , Local area networks (Computer networks) , Sound -- Recording and reproducing -- Digital techniques , Computational grids (Computer systems)
- Description: The control of modern audio studios is complex. Audio mixing desks have grown to the point where they contain thousands of parameters. The control surfaces of these devices do not reflect the routing and signal processing capabilities that the devices are capable of. Software audio mixing desk editors have been developed that allow for the remote control of these devices, but their graphical user interfaces retain the complexities of the audio mixing desk that they represent. In this thesis, we propose a grid approach to audio mixing. The developed grid audio mixing desk editor represents an audio mixing desk as a series of graphical routing matrices. These routing matrices expose the various signal processing points and signal flows that exist within an audio mixing desk. The routing matrices allow for audio signals to be routed within the device, and allow for the device’s parameters to be adjusted by selecting the appropriate signal processing points. With the use of the programming interfaces that are defined as part of the Studio Connections – Total Recall SDK, the audio mixing desk editor was integrated with compatible DAW applications to provide persistence of audio mixing desk parameter states. Many audio studios currently use digital networks to connect audio devices together. Audio and control signals are patched between devices through the use of software patchbays that run on computers. We propose a double grid-based FireWire patchbay aimed to simplify the patching of signals between audio devices on a FireWire network. The FireWire patchbay was implemented in such a way such that it can host software device editors that are Studio Connections compatible. This has allowed software device editors to be associated with the devices that are represented on the FireWire patchbay, thus allowing for studio wide control from a single application. The double grid-based patchbay was implemented such that it can be hosted by compatible DAW applications. Through this, the double grid-based patchbay application is able to provide the DAW application with the state of the parameters of the devices in a studio, as well as the connections between them. The DAW application may save this state data to its native song files. This state data may be passed back to the double grid-based patchbay when the song file is reloaded at a later stage. This state data may then be used by the patchbay to restore the parameters of the patchbay and its device editors to a previous state. This restored state may then be transferred to the hardware devices being represented by the patchbay.
- Full Text:
- Date Issued: 2009
- Authors: Foulkes, Philip James
- Date: 2009
- Subjects: IEEE 1394 (Standard) , Computer sound processing , Digital communications , Local area networks (Computer networks) , Sound -- Recording and reproducing -- Digital techniques , Computational grids (Computer systems)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4594 , http://hdl.handle.net/10962/d1004836 , IEEE 1394 (Standard) , Computer sound processing , Digital communications , Local area networks (Computer networks) , Sound -- Recording and reproducing -- Digital techniques , Computational grids (Computer systems)
- Description: The control of modern audio studios is complex. Audio mixing desks have grown to the point where they contain thousands of parameters. The control surfaces of these devices do not reflect the routing and signal processing capabilities that the devices are capable of. Software audio mixing desk editors have been developed that allow for the remote control of these devices, but their graphical user interfaces retain the complexities of the audio mixing desk that they represent. In this thesis, we propose a grid approach to audio mixing. The developed grid audio mixing desk editor represents an audio mixing desk as a series of graphical routing matrices. These routing matrices expose the various signal processing points and signal flows that exist within an audio mixing desk. The routing matrices allow for audio signals to be routed within the device, and allow for the device’s parameters to be adjusted by selecting the appropriate signal processing points. With the use of the programming interfaces that are defined as part of the Studio Connections – Total Recall SDK, the audio mixing desk editor was integrated with compatible DAW applications to provide persistence of audio mixing desk parameter states. Many audio studios currently use digital networks to connect audio devices together. Audio and control signals are patched between devices through the use of software patchbays that run on computers. We propose a double grid-based FireWire patchbay aimed to simplify the patching of signals between audio devices on a FireWire network. The FireWire patchbay was implemented in such a way such that it can host software device editors that are Studio Connections compatible. This has allowed software device editors to be associated with the devices that are represented on the FireWire patchbay, thus allowing for studio wide control from a single application. The double grid-based patchbay was implemented such that it can be hosted by compatible DAW applications. Through this, the double grid-based patchbay application is able to provide the DAW application with the state of the parameters of the devices in a studio, as well as the connections between them. The DAW application may save this state data to its native song files. This state data may be passed back to the double grid-based patchbay when the song file is reloaded at a later stage. This state data may then be used by the patchbay to restore the parameters of the patchbay and its device editors to a previous state. This restored state may then be transferred to the hardware devices being represented by the patchbay.
- Full Text:
- Date Issued: 2009
A potential biological role for microcystin in photosynthesis in Microcystis Aeruginosa
- Authors: Phelan, Richard Reginald
- Date: 2009
- Subjects: Microcystis aeruginosa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10320 , http://hdl.handle.net/10948/1285 , Microcystis aeruginosa
- Description: Neither the ecological role nor the metabolic function of microcystin is known. Cellular microcystin concentrations correlate to cellular nitrogen status for a given environmental phosphorous concentration and specific growth rate. Microcystin production is enhanced when the rate of nitrogen accumulation exceeds the relative specific growth rate and/or when cellular N:C ratios exceed the Redfield ratio as a function of reduced carbon fixation, suggesting enhanced production of microcystin under carbon stress. Additionally, a strong correlation between medium phosphate and carbon fixation, and the negative correlation between medium phosphate and microcystin combined with the cellular localization of microcystin in thylakoids supports a possible role for microcystin in enhancement of photosynthesis. Batch cultures of both Microcystis aeruginosa PCC7806 and a mcyA- knockout mutant of PCC7806 were therefore cultured at different light intensities and media treatments, so as to vary cellular N:C ratios and concentrations, and sampled for analysis of microcystin concentration, cell numbers and residual medium nitrates. Inter-strain differences in photosynthetic electron transfer rates and levels were monitored using a Hansatech PEA fluorometer and compared to cellular microcystin concentrations. An enhanced survival was observed at high light, where the toxic strain survived while the nontoxic strain became chlorotic. A strong correlation (r2 = 0.907, p< 0.001, N=22) between microcystin concentration and growth rate was observed at high light conditions. No such advantage was observed at optimal or low-light conditions and media composition had no significant effect on the relationship between toxicity and survival at high light. PCC7806 showed elevated PI(abs) values compared to the mcyA knockout strain, which indicates an increased stability of PSII. A strong correlation between PI(abs) and microcystin (r = 0.88, p< 0.005, N=15) was observed for cultures grown in modified BG11 containing 25 mM under continuous illumination of 37 μmol of photons m-2.s-1. No correlation was observed between PI(abs) and microcystin for the other treatments. The toxin producer had significantly higher values for density of active reaction centers and ii quantum efficiency compared to the mutant. A decrease in F0 in the mutant suggests degradation of the phycobiliproteins, whereas PCC7806 didn’t show a significant decrease in F0 Data indicate that microcystins play a role in photosynthesis by preventing chlorosis in saturating light conditions either by enhancing the redox stability of the phycobiliproteins or PS II, thus preventing photooxidation.
- Full Text:
- Date Issued: 2009
- Authors: Phelan, Richard Reginald
- Date: 2009
- Subjects: Microcystis aeruginosa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10320 , http://hdl.handle.net/10948/1285 , Microcystis aeruginosa
- Description: Neither the ecological role nor the metabolic function of microcystin is known. Cellular microcystin concentrations correlate to cellular nitrogen status for a given environmental phosphorous concentration and specific growth rate. Microcystin production is enhanced when the rate of nitrogen accumulation exceeds the relative specific growth rate and/or when cellular N:C ratios exceed the Redfield ratio as a function of reduced carbon fixation, suggesting enhanced production of microcystin under carbon stress. Additionally, a strong correlation between medium phosphate and carbon fixation, and the negative correlation between medium phosphate and microcystin combined with the cellular localization of microcystin in thylakoids supports a possible role for microcystin in enhancement of photosynthesis. Batch cultures of both Microcystis aeruginosa PCC7806 and a mcyA- knockout mutant of PCC7806 were therefore cultured at different light intensities and media treatments, so as to vary cellular N:C ratios and concentrations, and sampled for analysis of microcystin concentration, cell numbers and residual medium nitrates. Inter-strain differences in photosynthetic electron transfer rates and levels were monitored using a Hansatech PEA fluorometer and compared to cellular microcystin concentrations. An enhanced survival was observed at high light, where the toxic strain survived while the nontoxic strain became chlorotic. A strong correlation (r2 = 0.907, p< 0.001, N=22) between microcystin concentration and growth rate was observed at high light conditions. No such advantage was observed at optimal or low-light conditions and media composition had no significant effect on the relationship between toxicity and survival at high light. PCC7806 showed elevated PI(abs) values compared to the mcyA knockout strain, which indicates an increased stability of PSII. A strong correlation between PI(abs) and microcystin (r = 0.88, p< 0.005, N=15) was observed for cultures grown in modified BG11 containing 25 mM under continuous illumination of 37 μmol of photons m-2.s-1. No correlation was observed between PI(abs) and microcystin for the other treatments. The toxin producer had significantly higher values for density of active reaction centers and ii quantum efficiency compared to the mutant. A decrease in F0 in the mutant suggests degradation of the phycobiliproteins, whereas PCC7806 didn’t show a significant decrease in F0 Data indicate that microcystins play a role in photosynthesis by preventing chlorosis in saturating light conditions either by enhancing the redox stability of the phycobiliproteins or PS II, thus preventing photooxidation.
- Full Text:
- Date Issued: 2009
A preliminary investigation and photographic atlas of nodules found in the Bokkelveld group (Gydo formation), Steytlerville district, South Africa
- Authors: Browning, Claire
- Date: 2009
- Subjects: Gydo formation -- South Africa , Formations (Geology) -- South Africa -- Western Cape , Formations (Geology) -- South Africa -- Eastern Cape , Groups (Stratigraphy) -- South Africa -- Western Cape , Geology -- Stratigraphic , Bokkeveld group (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10656 , http://hdl.handle.net/10948/927 , Gydo formation -- South Africa , Formations (Geology) -- South Africa -- Western Cape , Formations (Geology) -- South Africa -- Eastern Cape , Groups (Stratigraphy) -- South Africa -- Western Cape , Geology -- Stratigraphic , Bokkeveld group (South Africa)
- Description: Nodules within the lower Bokkeveld shales often contain well-preserved invertebrate fossil material. The aim of this study was to describe some characteristics seen at various scales (macro-, micro- and ultra -) within nodules that might contribute to an understanding of aspects of nodule formation and the reasons for the excellent preservation of the fossil material within these nodules. Detailed, high quality macro-photographs were taken of sliced and whole nodule surfaces and a catalogue was produced to tentatively identify fossils present and illustrate the variations seen within nodules. Selected nodules were then subjected to petrographic, ultra-structural (SEM) and some chemical (EDS, XRD & XRF) analysis to investigate the possible reasons for these variations. The chemical results have indicated that nodules are enriched with quartz compared to the surrounding shale. Quartz is also the dominant mineral replacing trilobite carapace material within nodules, while trilobite material within shales is replaced with equal proportions of hematite, biotite and quartz. It appears that the higher resistance of quartz to weathering is the dominant factor leading to the preservation of both nodules within the shales and trilobite material within the nodules examined. A comparison with some Western Cape nodules highlighted possible variations in overall nodule chemical composition along strike. Western Cape nodules are predominantly composed of apatite whereas the Cockscomb nodules are mainly composed of quartz. This quartz-apatite compositional variation in nodules occurring within a single formation has been reported from nodules found in the Armorican Massif of France which are very similar in a number of respects to the Bokkeveld nodules described in this study. Based on various features of the fossils present and the structure of nodules they were probably formed during early diagenesis within an epeiric marine deposit greatly affected by sea level fluctuations.
- Full Text:
- Date Issued: 2009
- Authors: Browning, Claire
- Date: 2009
- Subjects: Gydo formation -- South Africa , Formations (Geology) -- South Africa -- Western Cape , Formations (Geology) -- South Africa -- Eastern Cape , Groups (Stratigraphy) -- South Africa -- Western Cape , Geology -- Stratigraphic , Bokkeveld group (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10656 , http://hdl.handle.net/10948/927 , Gydo formation -- South Africa , Formations (Geology) -- South Africa -- Western Cape , Formations (Geology) -- South Africa -- Eastern Cape , Groups (Stratigraphy) -- South Africa -- Western Cape , Geology -- Stratigraphic , Bokkeveld group (South Africa)
- Description: Nodules within the lower Bokkeveld shales often contain well-preserved invertebrate fossil material. The aim of this study was to describe some characteristics seen at various scales (macro-, micro- and ultra -) within nodules that might contribute to an understanding of aspects of nodule formation and the reasons for the excellent preservation of the fossil material within these nodules. Detailed, high quality macro-photographs were taken of sliced and whole nodule surfaces and a catalogue was produced to tentatively identify fossils present and illustrate the variations seen within nodules. Selected nodules were then subjected to petrographic, ultra-structural (SEM) and some chemical (EDS, XRD & XRF) analysis to investigate the possible reasons for these variations. The chemical results have indicated that nodules are enriched with quartz compared to the surrounding shale. Quartz is also the dominant mineral replacing trilobite carapace material within nodules, while trilobite material within shales is replaced with equal proportions of hematite, biotite and quartz. It appears that the higher resistance of quartz to weathering is the dominant factor leading to the preservation of both nodules within the shales and trilobite material within the nodules examined. A comparison with some Western Cape nodules highlighted possible variations in overall nodule chemical composition along strike. Western Cape nodules are predominantly composed of apatite whereas the Cockscomb nodules are mainly composed of quartz. This quartz-apatite compositional variation in nodules occurring within a single formation has been reported from nodules found in the Armorican Massif of France which are very similar in a number of respects to the Bokkeveld nodules described in this study. Based on various features of the fossils present and the structure of nodules they were probably formed during early diagenesis within an epeiric marine deposit greatly affected by sea level fluctuations.
- Full Text:
- Date Issued: 2009
A real time HF beacon monitoring station for South Africa
- Authors: Mudzingwa, Courage
- Date: 2009
- Subjects: Radio , Shortwave radio , Radio and television towers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5486 , http://hdl.handle.net/10962/d1005272 , Radio , Shortwave radio , Radio and television towers
- Description: High frequency, HF (3 - 30 MHz), radio communications are greatly affected by ionospheric conditions. Both civilian and military users need reliable, real time propagation information to show at any time the feasibility of communicating to any part of the world on a particular frequency band. For this thesis, an automated receiving/monitoring station for the Northern California DX Foundation (NCDXF)/ International Amateur Radio Union (IARU) International Beacon Project was setup at the Hermanus Magnetic Observatory, HMO (34.42oS, 19.22oE) to monitor international beacons on 20 m, 17 m, 15 m, 12 m and 10 m bands. The beacons form a world wide multiband network. The task of monitoring the beacons was broken down into two steps. Initially the single band station, at 14.10 MHz, was installed and later it was upgraded to a multiband station capable of automatically monitoring all the five HF bands. The single band station setup involved the construction and installation of the half-wave dipole antenna, construction and installation of an HF choke balun; and the choice of Faros 1.3 as the appropriate monitoring software. The multiband monitoring station set-up involved the installation of an MFJ-1778 G5RV multiband antenna, construction and installation of a Communication Interface - V (CI-V) level converter and configuring the Faros 1.3 software to monitor the beacons on all five HF bands. Then a web page was created on the HMO space weather website (http://spaceweather.hmo.ac.za). Here, the real-time signal to noise ratio (SNR) and short path (SP)/long path (LP) plots are uploaded every 3 minutes, showing real time HF propagation conditions on the five HF bands. Historical propagation data are archived for later analysis. A preliminary data analysis was done to confirm the peration of the monitoring station. The archived data were analysed and compared to ICEPAC (Ionospheric Communications Enhanced Profile Analysis and Circuit) predictions. Results show that the real-time signal plots as well as the archive of historical signal plots, convey information on ropagation conditions to users in terms that are easy to interpret and understand.
- Full Text:
- Date Issued: 2009
- Authors: Mudzingwa, Courage
- Date: 2009
- Subjects: Radio , Shortwave radio , Radio and television towers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5486 , http://hdl.handle.net/10962/d1005272 , Radio , Shortwave radio , Radio and television towers
- Description: High frequency, HF (3 - 30 MHz), radio communications are greatly affected by ionospheric conditions. Both civilian and military users need reliable, real time propagation information to show at any time the feasibility of communicating to any part of the world on a particular frequency band. For this thesis, an automated receiving/monitoring station for the Northern California DX Foundation (NCDXF)/ International Amateur Radio Union (IARU) International Beacon Project was setup at the Hermanus Magnetic Observatory, HMO (34.42oS, 19.22oE) to monitor international beacons on 20 m, 17 m, 15 m, 12 m and 10 m bands. The beacons form a world wide multiband network. The task of monitoring the beacons was broken down into two steps. Initially the single band station, at 14.10 MHz, was installed and later it was upgraded to a multiband station capable of automatically monitoring all the five HF bands. The single band station setup involved the construction and installation of the half-wave dipole antenna, construction and installation of an HF choke balun; and the choice of Faros 1.3 as the appropriate monitoring software. The multiband monitoring station set-up involved the installation of an MFJ-1778 G5RV multiband antenna, construction and installation of a Communication Interface - V (CI-V) level converter and configuring the Faros 1.3 software to monitor the beacons on all five HF bands. Then a web page was created on the HMO space weather website (http://spaceweather.hmo.ac.za). Here, the real-time signal to noise ratio (SNR) and short path (SP)/long path (LP) plots are uploaded every 3 minutes, showing real time HF propagation conditions on the five HF bands. Historical propagation data are archived for later analysis. A preliminary data analysis was done to confirm the peration of the monitoring station. The archived data were analysed and compared to ICEPAC (Ionospheric Communications Enhanced Profile Analysis and Circuit) predictions. Results show that the real-time signal plots as well as the archive of historical signal plots, convey information on ropagation conditions to users in terms that are easy to interpret and understand.
- Full Text:
- Date Issued: 2009
A resource allocation system for invasive alien plant control on the St. Francis Conservancy
- Authors: Reeves, Brian
- Date: 2009
- Subjects: Alien plants -- Control -- South Africa , Plant invasions -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10634 , http://hdl.handle.net/10948/1073 , Alien plants -- Control -- South Africa , Plant invasions -- South Africa
- Description: Alien invasive species pose a great threat to ecosystems and human communities (Richardson & van Wilgen 2004; Hobbs & Humphries 1995). On private lands, there is a need to find institutional, administrative and scientific responses to the alien plant problem that operate beyond the scale imposed by property boundaries (Slocombe 1998; Grumbine 1994). One such response is the development and support of institutions, such as the St Francis Conservancy, that foster cross-boundary management of landscapes (Hurley et al. 2002). This study seeks to promote collective decision-making and collaborative management by private landowners through the development of a resource allocation system for the control of alien invasive plants on the St Francis Conservancy. The conservancy is located in the south-eastern lowlands of the Cape Floristic Region, between the villages of Cape St Francis and Oyster Bay, and is comprised of the properties of multiple landowners. Mutliple Criteria Decision Analysis (MCDA) and Geographical Information Systems (GIS) techniques were integrated to provide a spatially explicit resource allocation system that considered environmental, social and economic concerns. The MCDA technique selected for use was the Analytical Hierarchy Process (AHP). This technique has a record of providing robust, defensible decisions and enabled the resource allocation decision-problem to be decomposed into a hierarchy of objectives, criteria and indicators. Stakeholders participated in the development of the resource allocation system, especially through providing input into the determination of the relative importance of criteria and indicators through the assignment of weights. Various weighting scenarios were presented and these were interpreted into an ii implementation plan. The costs and effort required to clear alien plants were estimated, and obstacles facing the implementation of the plan were identified.
- Full Text:
- Date Issued: 2009
- Authors: Reeves, Brian
- Date: 2009
- Subjects: Alien plants -- Control -- South Africa , Plant invasions -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10634 , http://hdl.handle.net/10948/1073 , Alien plants -- Control -- South Africa , Plant invasions -- South Africa
- Description: Alien invasive species pose a great threat to ecosystems and human communities (Richardson & van Wilgen 2004; Hobbs & Humphries 1995). On private lands, there is a need to find institutional, administrative and scientific responses to the alien plant problem that operate beyond the scale imposed by property boundaries (Slocombe 1998; Grumbine 1994). One such response is the development and support of institutions, such as the St Francis Conservancy, that foster cross-boundary management of landscapes (Hurley et al. 2002). This study seeks to promote collective decision-making and collaborative management by private landowners through the development of a resource allocation system for the control of alien invasive plants on the St Francis Conservancy. The conservancy is located in the south-eastern lowlands of the Cape Floristic Region, between the villages of Cape St Francis and Oyster Bay, and is comprised of the properties of multiple landowners. Mutliple Criteria Decision Analysis (MCDA) and Geographical Information Systems (GIS) techniques were integrated to provide a spatially explicit resource allocation system that considered environmental, social and economic concerns. The MCDA technique selected for use was the Analytical Hierarchy Process (AHP). This technique has a record of providing robust, defensible decisions and enabled the resource allocation decision-problem to be decomposed into a hierarchy of objectives, criteria and indicators. Stakeholders participated in the development of the resource allocation system, especially through providing input into the determination of the relative importance of criteria and indicators through the assignment of weights. Various weighting scenarios were presented and these were interpreted into an ii implementation plan. The costs and effort required to clear alien plants were estimated, and obstacles facing the implementation of the plan were identified.
- Full Text:
- Date Issued: 2009
A situational analysis on the public participation processes in integrated water resources management in the Kat River Valley, Eastern Cape, South Africa
- Authors: Naidoo, Merle
- Date: 2009
- Subjects: South Africa. Dept. of Water Affairs and Forestry , Water-supply -- South Africa -- Kat River Valley , Water quality management -- South Africa -- Kat River Valley , Water-supply -- Government policy -- South Africa -- Kat River Valley , Water resources development -- South Africa -- Kat River Valley , Integrated water development -- South Africa -- Kat River Valley , Rural development -- South Africa -- Kat River Valley
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4854 , http://hdl.handle.net/10962/d1005530 , South Africa. Dept. of Water Affairs and Forestry , Water-supply -- South Africa -- Kat River Valley , Water quality management -- South Africa -- Kat River Valley , Water-supply -- Government policy -- South Africa -- Kat River Valley , Water resources development -- South Africa -- Kat River Valley , Integrated water development -- South Africa -- Kat River Valley , Rural development -- South Africa -- Kat River Valley
- Description: Public participation in water management processes is one of the internationally recognised and adopted principles of Integrated Water Resource Management. The South African Department of Water Affairs and Forestry aims to facilitate the decentralisation of water management powers to the local community level via the establishment of regional and local water management institutions, namely Catchment Management Agencies, Water User Associations and Catchment Forums. The National Water Act (No. 36 of 1998) acknowledges that the discriminatory laws and practices of the past have prevented equal access to water and the use of water resources. The contribution of water management institutions to social and economic development, in particular poverty eradication and food security, is mentioned in the water act. The participation of poor rural communities living in the Kat valley, an area where an elite minority reap the benefits of water use for agriculture, is the focus of this research. Their participation, perceptions and experiences are documented and explored to determine how the promulgation of post-apartheid water policy and legislation has affected their access to water. The results of this research are based on data collected from several methods including surveys, workshops and observation. Analysis of these data revealed the complicated and stagnant nature of participation from Kat valley rural communities in local water management initiatives and organisations. Existing water management organisations were not successful in stimulating poor people’s participation as they were unable to address their primary concerns, namely a secure source of potable water, employment and access to water for agricultural purposes. This thesis asserts that the Department of Water Affairs and Forestry, as the custodian of South Africa’s water resources, has not taken on a supportive, accountable role in assisting marginalised communities with improving their access to water for domestic purposes and securing access to water rights for productive use. This, in turn, has led to dissatisfaction among these communities and a wariness of participatory activities that focus mainly on raising environmental awareness. The establishment of effective accountability relationships among all stakeholders, pro-poor water management structures and initiatives, as well as integrated and co-operative management of natural resources, are needed to revitalise the present participation of poor communities living in rural areas.
- Full Text:
- Date Issued: 2009
- Authors: Naidoo, Merle
- Date: 2009
- Subjects: South Africa. Dept. of Water Affairs and Forestry , Water-supply -- South Africa -- Kat River Valley , Water quality management -- South Africa -- Kat River Valley , Water-supply -- Government policy -- South Africa -- Kat River Valley , Water resources development -- South Africa -- Kat River Valley , Integrated water development -- South Africa -- Kat River Valley , Rural development -- South Africa -- Kat River Valley
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4854 , http://hdl.handle.net/10962/d1005530 , South Africa. Dept. of Water Affairs and Forestry , Water-supply -- South Africa -- Kat River Valley , Water quality management -- South Africa -- Kat River Valley , Water-supply -- Government policy -- South Africa -- Kat River Valley , Water resources development -- South Africa -- Kat River Valley , Integrated water development -- South Africa -- Kat River Valley , Rural development -- South Africa -- Kat River Valley
- Description: Public participation in water management processes is one of the internationally recognised and adopted principles of Integrated Water Resource Management. The South African Department of Water Affairs and Forestry aims to facilitate the decentralisation of water management powers to the local community level via the establishment of regional and local water management institutions, namely Catchment Management Agencies, Water User Associations and Catchment Forums. The National Water Act (No. 36 of 1998) acknowledges that the discriminatory laws and practices of the past have prevented equal access to water and the use of water resources. The contribution of water management institutions to social and economic development, in particular poverty eradication and food security, is mentioned in the water act. The participation of poor rural communities living in the Kat valley, an area where an elite minority reap the benefits of water use for agriculture, is the focus of this research. Their participation, perceptions and experiences are documented and explored to determine how the promulgation of post-apartheid water policy and legislation has affected their access to water. The results of this research are based on data collected from several methods including surveys, workshops and observation. Analysis of these data revealed the complicated and stagnant nature of participation from Kat valley rural communities in local water management initiatives and organisations. Existing water management organisations were not successful in stimulating poor people’s participation as they were unable to address their primary concerns, namely a secure source of potable water, employment and access to water for agricultural purposes. This thesis asserts that the Department of Water Affairs and Forestry, as the custodian of South Africa’s water resources, has not taken on a supportive, accountable role in assisting marginalised communities with improving their access to water for domestic purposes and securing access to water rights for productive use. This, in turn, has led to dissatisfaction among these communities and a wariness of participatory activities that focus mainly on raising environmental awareness. The establishment of effective accountability relationships among all stakeholders, pro-poor water management structures and initiatives, as well as integrated and co-operative management of natural resources, are needed to revitalise the present participation of poor communities living in rural areas.
- Full Text:
- Date Issued: 2009
A Speciation study of the chloro-hydroxo complexes of Pt(II)
- Authors: Davis, John Christopher
- Date: 2009
- Subjects: Platinum , Platinum -- Separation , Platinum compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10388 , http://hdl.handle.net/10948/1213 , Platinum , Platinum -- Separation , Platinum compounds
- Description: In this study a method was developed to identify and quantify platinum(II) complexes of the type [PtCl4-n(OH)n]2- and [PtCl4-n(H2O)n]2-n. Separation of the various species was achieved with the aid of a hyphenated reversed phase HPLC-ICP-MS technique coupled with an ion-pairing reagent, HMHDCl2. The adsorption of HMHD2+ onto a C-18 column was investigated by generating a series of breakthrough curves. It was found that the selectivity for high charge density anions originates from its low surface coverage relative to TBA+, which on the other hand could not separate Pt(II) complexes. The peaks in the chromatographic traces were assigned by following the stepwise ligand substitution of [PtCl4]2- in hydroxide medium with UV/Vis spectrophotometry and HPLC-ICP-MS simultaneously. A computer program was written by the author to analyse chromatographic data by deconvoluting the chromatogram into its individual components and calculating the mole fraction of each component. The validity of the consecutive pseudo-first order model was validated by constructing 3D Mauser diagrams with the raw spectrophotometric data (A1 vs A2 vs A3). Additional software was used to simulate the raw spectrophotometric data and processed chromatographic data. The pseudo-first order rate constants obtained in both cases were in agreement with each other. Hence, peaks were assigned to [PtCl4]2-, [PtCl3(OH)]2-, [PtCl2(OH)2]2-, [PtCl3(H2O)]-. The molar extinction coefficient spectra of [PtCl3(OH)]2- and [PtCl2(OH)2]2- were obtained by simulating the spectrophotometric data at wavelengths from 280 to 450 nm. The reaction of [PtCl4]2- with sodium hydroxide was investigated with UV/Vis spectrophotometry at 25 °C. A rate constant consisting of a first and second order term was obtained. The first order term agreed with what has been reported in the literature for aquation of [PtCl4]2- at 25 degrees C. The influence of temperature was established by conducting the experiment at different temperatures. It was found that the reaction proceeds essentially via aquation at elevated temperatures.
- Full Text:
- Date Issued: 2009
- Authors: Davis, John Christopher
- Date: 2009
- Subjects: Platinum , Platinum -- Separation , Platinum compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10388 , http://hdl.handle.net/10948/1213 , Platinum , Platinum -- Separation , Platinum compounds
- Description: In this study a method was developed to identify and quantify platinum(II) complexes of the type [PtCl4-n(OH)n]2- and [PtCl4-n(H2O)n]2-n. Separation of the various species was achieved with the aid of a hyphenated reversed phase HPLC-ICP-MS technique coupled with an ion-pairing reagent, HMHDCl2. The adsorption of HMHD2+ onto a C-18 column was investigated by generating a series of breakthrough curves. It was found that the selectivity for high charge density anions originates from its low surface coverage relative to TBA+, which on the other hand could not separate Pt(II) complexes. The peaks in the chromatographic traces were assigned by following the stepwise ligand substitution of [PtCl4]2- in hydroxide medium with UV/Vis spectrophotometry and HPLC-ICP-MS simultaneously. A computer program was written by the author to analyse chromatographic data by deconvoluting the chromatogram into its individual components and calculating the mole fraction of each component. The validity of the consecutive pseudo-first order model was validated by constructing 3D Mauser diagrams with the raw spectrophotometric data (A1 vs A2 vs A3). Additional software was used to simulate the raw spectrophotometric data and processed chromatographic data. The pseudo-first order rate constants obtained in both cases were in agreement with each other. Hence, peaks were assigned to [PtCl4]2-, [PtCl3(OH)]2-, [PtCl2(OH)2]2-, [PtCl3(H2O)]-. The molar extinction coefficient spectra of [PtCl3(OH)]2- and [PtCl2(OH)2]2- were obtained by simulating the spectrophotometric data at wavelengths from 280 to 450 nm. The reaction of [PtCl4]2- with sodium hydroxide was investigated with UV/Vis spectrophotometry at 25 °C. A rate constant consisting of a first and second order term was obtained. The first order term agreed with what has been reported in the literature for aquation of [PtCl4]2- at 25 degrees C. The influence of temperature was established by conducting the experiment at different temperatures. It was found that the reaction proceeds essentially via aquation at elevated temperatures.
- Full Text:
- Date Issued: 2009
African traditional medicines-antiretroviral drug interactions: the effect of African potato (Hypoxis hemerocallidea) on the pharmacokinetics of efavirenz in humans
- Authors: Mogatle, Seloi
- Date: 2009
- Subjects: Potatoes -- Africa Potatoes -- Therapeutic use Medicinal plants Traditional medicine AIDS (Disease) -- Treatment HIV infections -- Drug therapy Drug interactions Antiretroviral agents Pharmacokinetics Hypoxidaceae -- Therapeutic use High performance liquid chromatography
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3773 , http://hdl.handle.net/10962/d1003251
- Description: African Potato (Hypoxis hemerocallidea), (AP) is an African traditional medicine (TM) that is commonly used for various nutritional/medicinal purposes and also by people infected with the human immuno deficiency virus HIV and AIDS patients as an immune booster. The use of AP has also been recommended by the former Minister of Health of South Africa for use by HIV positive people. The main phytochemical component of AP is a norlignan glucoside, hypoxoside, and other relatively minor components have also been reported. A recent in vitro study reported the effects of AP extracts, hypoxoside and rooperol (the metabolite of hypoxoside) on human metabolic enzymes such as the cytochrome P450 (CYP450) group of enzymes and also on the transporter protein, p-glycoprotein (P-gp). This research focussed on investigating the clinical significance of those in vitro effects on the pharmacokinetics of efavirenz (EFV) in humans. EFV was chosen as the substrate drug because it is in first-line regimen of treatment of HIV/AIDS in South Africa, and also has been reported to be a substrate for the specific CYP isozymes, 3A4 and 2B6, in common with APs metabolic involvement with 3A4. A high performance liquid chromatography method with ultra-violet detection (HPLC-UV) for the quantitative determination of EFV in plasma was developed and successfully validated according to international standards with good reproducibility, accuracy, recovery, linear response and requisite sensitivity. The preparation of the plasma samples for analysis was effected by using a simple and rapid precipitation method, and the mobile phase consisted of readily available solvents. EFV in plasma samples was found to be stable under the relevant storage conditions studied. The oral dose of AP, administered as a freshly prepared traditional decoction, was standardised based on the hypoxoside content, and the quality of all the AP decoctions was analysed immediately prior to administration, using a validated HPLC-UV method. A single dose, two-phase sequential study was conducted over a period of 31 days in 10 healthy volunteers. The clinical study was approved by the Rhodes University Ethical Standards Committee, and all the participants agreed to the conditions of the study by giving their informed consent. On day 1 of the study, human subjects were administered a 600 mg EFV tablet and blood samples were collected before dosing and at various intervals over a period of 48 hr post dosing. From day 16, a traditionally prepared AP decoction was administered daily at a standardized dose of 15 mg/kg/day per subject until day 30. On day 29, volunteers were administered a single 600 mg dose of EFV as was done on day 1. Plasma samples were harvested immediately after blood sample collection and frozen at -80 ºC until assayed. Geometric mean ratios of relevant pharmacokinetic parameters, Cmax (maximum plasma concentration achieved following dosing) and AUC0-48 (area under the curve of a plot of drug plasma concentrations versus time representing the extent of absorption) of EFV before and after co-administration of 14 successive daily doses of AP were compared and evaluated to determine whether an interaction had occurred. All subjects completed the study and the geometric mean ratios of Cmax and AUC0-48 were 97.30 and 102.82 with corresponding 90% confidence intervals (CIs) of 78.81-120.14% and 89.04-118.80%, respectively. Whereas the acceptance criteria for the ratios of the AUCs fell within the preset 90% CIs indicating no interaction, the Cmax ratios fell outside the limits. Although the protocol was developed in accordance with the United States of America Food & Drug Administration’s Guidance for Drug Interactions, a priori stating that both criteria need to fall within the acceptance limits to indicate no interaction, an argument is presented to waive the Cmax requirement for the declaration of an interaction. As a result, the pharmacokinetic data generated during this study indicated that the effect of AP on the pharmacokinetics of EFV is not clinically significant. Hence, co-administration of AP is unlikely to affect the clinical use of EFV. In summary the objectives of this project were: 1. To develop and validate a suitable HPLC-UV method for the quantitative determination of EFV in plasma. 2. To perform a mini-validation of the determination of hypoxoside for use as a marker in the quality control and standardisation of AP decoctions. 3. To conduct a clinical interaction study in order to determine whether AP affects the pharmacokinetics of EFV following concurrent administration. 4. To apply the validated HPLC-UV method to determine plasma concentrations of EFV in plasma of human subjects. 5. To use appropriate statistical methods and treatments such as a non-compartmental pharmacokinetic analysis to determine the occurrence of an interaction.
- Full Text:
- Date Issued: 2009
- Authors: Mogatle, Seloi
- Date: 2009
- Subjects: Potatoes -- Africa Potatoes -- Therapeutic use Medicinal plants Traditional medicine AIDS (Disease) -- Treatment HIV infections -- Drug therapy Drug interactions Antiretroviral agents Pharmacokinetics Hypoxidaceae -- Therapeutic use High performance liquid chromatography
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3773 , http://hdl.handle.net/10962/d1003251
- Description: African Potato (Hypoxis hemerocallidea), (AP) is an African traditional medicine (TM) that is commonly used for various nutritional/medicinal purposes and also by people infected with the human immuno deficiency virus HIV and AIDS patients as an immune booster. The use of AP has also been recommended by the former Minister of Health of South Africa for use by HIV positive people. The main phytochemical component of AP is a norlignan glucoside, hypoxoside, and other relatively minor components have also been reported. A recent in vitro study reported the effects of AP extracts, hypoxoside and rooperol (the metabolite of hypoxoside) on human metabolic enzymes such as the cytochrome P450 (CYP450) group of enzymes and also on the transporter protein, p-glycoprotein (P-gp). This research focussed on investigating the clinical significance of those in vitro effects on the pharmacokinetics of efavirenz (EFV) in humans. EFV was chosen as the substrate drug because it is in first-line regimen of treatment of HIV/AIDS in South Africa, and also has been reported to be a substrate for the specific CYP isozymes, 3A4 and 2B6, in common with APs metabolic involvement with 3A4. A high performance liquid chromatography method with ultra-violet detection (HPLC-UV) for the quantitative determination of EFV in plasma was developed and successfully validated according to international standards with good reproducibility, accuracy, recovery, linear response and requisite sensitivity. The preparation of the plasma samples for analysis was effected by using a simple and rapid precipitation method, and the mobile phase consisted of readily available solvents. EFV in plasma samples was found to be stable under the relevant storage conditions studied. The oral dose of AP, administered as a freshly prepared traditional decoction, was standardised based on the hypoxoside content, and the quality of all the AP decoctions was analysed immediately prior to administration, using a validated HPLC-UV method. A single dose, two-phase sequential study was conducted over a period of 31 days in 10 healthy volunteers. The clinical study was approved by the Rhodes University Ethical Standards Committee, and all the participants agreed to the conditions of the study by giving their informed consent. On day 1 of the study, human subjects were administered a 600 mg EFV tablet and blood samples were collected before dosing and at various intervals over a period of 48 hr post dosing. From day 16, a traditionally prepared AP decoction was administered daily at a standardized dose of 15 mg/kg/day per subject until day 30. On day 29, volunteers were administered a single 600 mg dose of EFV as was done on day 1. Plasma samples were harvested immediately after blood sample collection and frozen at -80 ºC until assayed. Geometric mean ratios of relevant pharmacokinetic parameters, Cmax (maximum plasma concentration achieved following dosing) and AUC0-48 (area under the curve of a plot of drug plasma concentrations versus time representing the extent of absorption) of EFV before and after co-administration of 14 successive daily doses of AP were compared and evaluated to determine whether an interaction had occurred. All subjects completed the study and the geometric mean ratios of Cmax and AUC0-48 were 97.30 and 102.82 with corresponding 90% confidence intervals (CIs) of 78.81-120.14% and 89.04-118.80%, respectively. Whereas the acceptance criteria for the ratios of the AUCs fell within the preset 90% CIs indicating no interaction, the Cmax ratios fell outside the limits. Although the protocol was developed in accordance with the United States of America Food & Drug Administration’s Guidance for Drug Interactions, a priori stating that both criteria need to fall within the acceptance limits to indicate no interaction, an argument is presented to waive the Cmax requirement for the declaration of an interaction. As a result, the pharmacokinetic data generated during this study indicated that the effect of AP on the pharmacokinetics of EFV is not clinically significant. Hence, co-administration of AP is unlikely to affect the clinical use of EFV. In summary the objectives of this project were: 1. To develop and validate a suitable HPLC-UV method for the quantitative determination of EFV in plasma. 2. To perform a mini-validation of the determination of hypoxoside for use as a marker in the quality control and standardisation of AP decoctions. 3. To conduct a clinical interaction study in order to determine whether AP affects the pharmacokinetics of EFV following concurrent administration. 4. To apply the validated HPLC-UV method to determine plasma concentrations of EFV in plasma of human subjects. 5. To use appropriate statistical methods and treatments such as a non-compartmental pharmacokinetic analysis to determine the occurrence of an interaction.
- Full Text:
- Date Issued: 2009
An investigation into a natural language interface for contact centers
- Authors: Sankar, Gopal Ravi
- Date: 2009
- Subjects: Call centers -- Management , Customer services -- Management , Telephone selling
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10468 , http://hdl.handle.net/10948/890 , Call centers -- Management , Customer services -- Management , Telephone selling
- Description: Contact centres are the first point of contact between a company and a customer after the purchase of a product or service. These centres make use of contact centre agents to service customer queries. In the past contact centres hired as many agents as they could in order to service customers, which have led to an increase in personnel costs causing contact centres to become costly to run. Automation techniques were introduced to decrease personnel costs and one such technique is the Interactive Voice Response (IVR). The usability of IVR systems is, however, dismal. Customers would rather speak to a contact centre agent than navigate through the menu structure found in these systems. The menu structure has come under scrutiny because it is difficult to use and navigate, is often not aligned to caller usage patterns, and the menu options are long and vague. This research investigated whether a Natural Language Interface (NLI) could alleviate the problems inherent to IVR. NLIs, however, come with their own disadvantages of which the main ones are ambiguity and the loss of context of a conversation. Two prototypes were implemented, one of which resembled an IVR and the other an NLI (using ALICE concepts). An evaluation of two prototypes confirmed the advantages and disadvantages of these concepts in accordance to theory. A Hybrid prototype was proposed with the aid of two models. The model which proposed an NLI using a rule base was chosen for implementation. The Hybrid prototype was then evaluated against the NLI and IVR prototypes to deduce which prototype was the most effective, efficient and satisfying. The evaluation through the aid of descriptive and inferential statistics showed that the Hybrid prototype was the most usable prototype. The evaluation of the Hybrid prototype confirmed that a Hybrid approach could limit the shortcomings of IVR through the elimination of the menu structure found in these systems, thereby allowing users to state their queries in natural language. The incorporated rule base provided the Hybrid system with long term memory, eliminating one of the main disadvantages of NLIs.
- Full Text:
- Date Issued: 2009
- Authors: Sankar, Gopal Ravi
- Date: 2009
- Subjects: Call centers -- Management , Customer services -- Management , Telephone selling
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10468 , http://hdl.handle.net/10948/890 , Call centers -- Management , Customer services -- Management , Telephone selling
- Description: Contact centres are the first point of contact between a company and a customer after the purchase of a product or service. These centres make use of contact centre agents to service customer queries. In the past contact centres hired as many agents as they could in order to service customers, which have led to an increase in personnel costs causing contact centres to become costly to run. Automation techniques were introduced to decrease personnel costs and one such technique is the Interactive Voice Response (IVR). The usability of IVR systems is, however, dismal. Customers would rather speak to a contact centre agent than navigate through the menu structure found in these systems. The menu structure has come under scrutiny because it is difficult to use and navigate, is often not aligned to caller usage patterns, and the menu options are long and vague. This research investigated whether a Natural Language Interface (NLI) could alleviate the problems inherent to IVR. NLIs, however, come with their own disadvantages of which the main ones are ambiguity and the loss of context of a conversation. Two prototypes were implemented, one of which resembled an IVR and the other an NLI (using ALICE concepts). An evaluation of two prototypes confirmed the advantages and disadvantages of these concepts in accordance to theory. A Hybrid prototype was proposed with the aid of two models. The model which proposed an NLI using a rule base was chosen for implementation. The Hybrid prototype was then evaluated against the NLI and IVR prototypes to deduce which prototype was the most effective, efficient and satisfying. The evaluation through the aid of descriptive and inferential statistics showed that the Hybrid prototype was the most usable prototype. The evaluation of the Hybrid prototype confirmed that a Hybrid approach could limit the shortcomings of IVR through the elimination of the menu structure found in these systems, thereby allowing users to state their queries in natural language. The incorporated rule base provided the Hybrid system with long term memory, eliminating one of the main disadvantages of NLIs.
- Full Text:
- Date Issued: 2009
An investigation into the design and implementation of an internet-scale network simulator
- Authors: Richter, John Peter Frank
- Date: 2009
- Subjects: Computer simulation , Computer network resources , Computer networks , Internet
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4597 , http://hdl.handle.net/10962/d1004840 , Computer simulation , Computer network resources , Computer networks , Internet
- Description: Simulation is a complex task with many research applications - chiey as a research tool, to test and evaluate hypothetical scenarios. Though many simulations execute similar operations and utilise similar data, there are few simulation frameworks or toolkits that allow researchers to rapidly develop their concepts. Those that are available to researchers are limited in scope, or use old technology that is no longer useful to modern researchers. As a result of this, many researchers build their own simulations without a framework, wasting time and resources on a system that could already cater for the majority of their simulation's requirements. In this work, a system is proposed for the creation of a scalable, dynamic-resolution network simulation framework that provides scalable scope for researchers, using modern technologies and languages. This framework should allow researchers to rapidly develop a broad range of semantically-rich simulations, without the necessity of superor grid-computers or clusters. Design and implementation are discussed and alternative network simulations are compared to the proposed framework. A series of simulations, focusing on malware, is run on an implementation of this framework, and the results are compared to expectations for the outcomes of those simulations. In conclusion, a critical review of the simulator is made, considering any extensions or shortcomings that need to be addressed.
- Full Text:
- Date Issued: 2009
- Authors: Richter, John Peter Frank
- Date: 2009
- Subjects: Computer simulation , Computer network resources , Computer networks , Internet
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4597 , http://hdl.handle.net/10962/d1004840 , Computer simulation , Computer network resources , Computer networks , Internet
- Description: Simulation is a complex task with many research applications - chiey as a research tool, to test and evaluate hypothetical scenarios. Though many simulations execute similar operations and utilise similar data, there are few simulation frameworks or toolkits that allow researchers to rapidly develop their concepts. Those that are available to researchers are limited in scope, or use old technology that is no longer useful to modern researchers. As a result of this, many researchers build their own simulations without a framework, wasting time and resources on a system that could already cater for the majority of their simulation's requirements. In this work, a system is proposed for the creation of a scalable, dynamic-resolution network simulation framework that provides scalable scope for researchers, using modern technologies and languages. This framework should allow researchers to rapidly develop a broad range of semantically-rich simulations, without the necessity of superor grid-computers or clusters. Design and implementation are discussed and alternative network simulations are compared to the proposed framework. A series of simulations, focusing on malware, is run on an implementation of this framework, and the results are compared to expectations for the outcomes of those simulations. In conclusion, a critical review of the simulator is made, considering any extensions or shortcomings that need to be addressed.
- Full Text:
- Date Issued: 2009
An investigation into the hardware abstraction layer of the plural node architecture for IEEE 1394 audio devices
- Authors: Chigwamba, Nyasha
- Date: 2009
- Subjects: IEEE 1394 (Standard) , Digital communications , Computer sound processing , Local area networks (Computer networks) , Computer network architectures , Sound -- Recording and reproducing -- Digital techniques
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4598 , http://hdl.handle.net/10962/d1004841 , IEEE 1394 (Standard) , Digital communications , Computer sound processing , Local area networks (Computer networks) , Computer network architectures , Sound -- Recording and reproducing -- Digital techniques
- Description: Digital audio network technologies are becoming more prevalent in audio related environments. Yamaha Corporation has created a digital audio network solution, named mLAN (music Local Area Network), that uses IEEE 1394 as its underlying network technology. IEEE 1394 is a digital network technology that is specifically designed for real-time multimedia data transmission. The second generation of mLAN is based on the Plural Node Architecture, where the control of audio and MIDI routings between IEEE 1394 devices is split between two node types, namely an Enabler and a Transporter. The Transporter typically resides in an IEEE 1394 device and is solely responsible for transmission and reception of audio or MIDI data. The Enabler typically resides in a workstation and exposes an abstract representation of audio or MIDI plugs on each Transporter to routing control applications. The Enabler is responsible for configuring audio and MIDI routings between plugs on different Transporters. A Hardware Abstraction Layer (HAL) within the Enabler allows it to uniformly communicate with Transporters that are created by various vendors. A plug-in mechanism is used to provide this capability. When vendors create Transporters, they also create device-specific plug-ins for the Enabler. These plug-ins are created against a Transporter HAL Application Programming Interface (API) that defines methods to access the capabilities of Transporters. An Open Generic Transporter (OGT) guideline document which models all the capabilities of Transporters has been produced. These guidelines make it possible for manufacturers to create Transporters that make use of a common plug-in, although based on different hardware architectures. The introduction of the OGT concept has revealed additional Transporter capabilities that are not incorporated in the existing Transporter HAL API. This has led to the underutilisation of OGT capabilities. The main goals of this investigation have been to improve the Enabler’s plug-in mechanism, and to incorporate the additional capabilities that have been revealed by the OGT into the Transporter HAL API. We propose a new plug-in mechanism, and a new Transporter HAL API that fully utilises both the additional capabilities revealed by the OGT and the capabilities of existing Transporters.
- Full Text:
- Date Issued: 2009
- Authors: Chigwamba, Nyasha
- Date: 2009
- Subjects: IEEE 1394 (Standard) , Digital communications , Computer sound processing , Local area networks (Computer networks) , Computer network architectures , Sound -- Recording and reproducing -- Digital techniques
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4598 , http://hdl.handle.net/10962/d1004841 , IEEE 1394 (Standard) , Digital communications , Computer sound processing , Local area networks (Computer networks) , Computer network architectures , Sound -- Recording and reproducing -- Digital techniques
- Description: Digital audio network technologies are becoming more prevalent in audio related environments. Yamaha Corporation has created a digital audio network solution, named mLAN (music Local Area Network), that uses IEEE 1394 as its underlying network technology. IEEE 1394 is a digital network technology that is specifically designed for real-time multimedia data transmission. The second generation of mLAN is based on the Plural Node Architecture, where the control of audio and MIDI routings between IEEE 1394 devices is split between two node types, namely an Enabler and a Transporter. The Transporter typically resides in an IEEE 1394 device and is solely responsible for transmission and reception of audio or MIDI data. The Enabler typically resides in a workstation and exposes an abstract representation of audio or MIDI plugs on each Transporter to routing control applications. The Enabler is responsible for configuring audio and MIDI routings between plugs on different Transporters. A Hardware Abstraction Layer (HAL) within the Enabler allows it to uniformly communicate with Transporters that are created by various vendors. A plug-in mechanism is used to provide this capability. When vendors create Transporters, they also create device-specific plug-ins for the Enabler. These plug-ins are created against a Transporter HAL Application Programming Interface (API) that defines methods to access the capabilities of Transporters. An Open Generic Transporter (OGT) guideline document which models all the capabilities of Transporters has been produced. These guidelines make it possible for manufacturers to create Transporters that make use of a common plug-in, although based on different hardware architectures. The introduction of the OGT concept has revealed additional Transporter capabilities that are not incorporated in the existing Transporter HAL API. This has led to the underutilisation of OGT capabilities. The main goals of this investigation have been to improve the Enabler’s plug-in mechanism, and to incorporate the additional capabilities that have been revealed by the OGT into the Transporter HAL API. We propose a new plug-in mechanism, and a new Transporter HAL API that fully utilises both the additional capabilities revealed by the OGT and the capabilities of existing Transporters.
- Full Text:
- Date Issued: 2009
An investigation of the factors influencing vegetation stress in a part of the Keiskamma catchment, Eastern Cape : a remote sensing and GIS approach
- Haindongo, Priscilla Nauwanga
- Authors: Haindongo, Priscilla Nauwanga
- Date: 2009
- Subjects: Plants, Effect of stress on -- South Africa -- Eastern Cape , Land use -- South Africa -- Eastern Cape , Vegetation and climate -- South Africa -- Eastern Cape , Ecology -- South Africa -- Eastern Cape -- Remote sensing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10652 , http://hdl.handle.net/10948/975 , Plants, Effect of stress on -- South Africa -- Eastern Cape , Land use -- South Africa -- Eastern Cape , Vegetation and climate -- South Africa -- Eastern Cape , Ecology -- South Africa -- Eastern Cape -- Remote sensing
- Description: Vegetation stress as a form of degradation is a widespread problem in many catchments in the Eastern Cape province. The Keiskamma is one of the catchments where considerable parts of the thicket biome are stressed. This necessitates an assessment of the status of the thicket biome by way of detecting vegetation stress in the area. The underpinnings of vegetation stress are investigated in this study. As a basic method to evaluate the thicket condition, remotely sensed data were acquired. High resolution ASTER imagery for the Keiskamma area at two different dates (2001 and 2005) was used to compute SVI and NDVI as indicators of vegetation stress conditions. A Digital Elevation Model (DEM) was used to derive slope angle and aspect. By way of digitizing from ortho-photo maps, various land-use types were mapped using Arc View GIS. The relationship between land use, terrain, soil erosion and vegetation stress was established. Field based techniques comprising stomatal conductance measurements were used and compared to remotely sensed data. The SVI and NDVI resultant images expressed similarities in areas depicting vegetation stress conditions at both epochs. A strong linear regression between NDVI and stomatal conductance measurements (mmol/m²) serve to confirm that the NDVI is a reliable indicator of vegetation stress condition. Slope angle and aspect were found to have a significant influence on vegetation stress conditions. Similarly variations in soil moisture and soil surface condition have strong implications for vegetation stress. Amongst other land-use types, abandoned lands were found to have the lowest NDVI values implying an association with the worst vegetation stress scenarios. It was concluded that an element of persistent stress conditions exists amongst the thicket vegetation of the Keiskamma catchment. This was mainly due to land use activities in the area.
- Full Text:
- Date Issued: 2009
- Authors: Haindongo, Priscilla Nauwanga
- Date: 2009
- Subjects: Plants, Effect of stress on -- South Africa -- Eastern Cape , Land use -- South Africa -- Eastern Cape , Vegetation and climate -- South Africa -- Eastern Cape , Ecology -- South Africa -- Eastern Cape -- Remote sensing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10652 , http://hdl.handle.net/10948/975 , Plants, Effect of stress on -- South Africa -- Eastern Cape , Land use -- South Africa -- Eastern Cape , Vegetation and climate -- South Africa -- Eastern Cape , Ecology -- South Africa -- Eastern Cape -- Remote sensing
- Description: Vegetation stress as a form of degradation is a widespread problem in many catchments in the Eastern Cape province. The Keiskamma is one of the catchments where considerable parts of the thicket biome are stressed. This necessitates an assessment of the status of the thicket biome by way of detecting vegetation stress in the area. The underpinnings of vegetation stress are investigated in this study. As a basic method to evaluate the thicket condition, remotely sensed data were acquired. High resolution ASTER imagery for the Keiskamma area at two different dates (2001 and 2005) was used to compute SVI and NDVI as indicators of vegetation stress conditions. A Digital Elevation Model (DEM) was used to derive slope angle and aspect. By way of digitizing from ortho-photo maps, various land-use types were mapped using Arc View GIS. The relationship between land use, terrain, soil erosion and vegetation stress was established. Field based techniques comprising stomatal conductance measurements were used and compared to remotely sensed data. The SVI and NDVI resultant images expressed similarities in areas depicting vegetation stress conditions at both epochs. A strong linear regression between NDVI and stomatal conductance measurements (mmol/m²) serve to confirm that the NDVI is a reliable indicator of vegetation stress condition. Slope angle and aspect were found to have a significant influence on vegetation stress conditions. Similarly variations in soil moisture and soil surface condition have strong implications for vegetation stress. Amongst other land-use types, abandoned lands were found to have the lowest NDVI values implying an association with the worst vegetation stress scenarios. It was concluded that an element of persistent stress conditions exists amongst the thicket vegetation of the Keiskamma catchment. This was mainly due to land use activities in the area.
- Full Text:
- Date Issued: 2009
Analytic pricing of American put options
- Authors: Glover, Elistan Nicholas
- Date: 2009
- Subjects: Options (Finance) -- Prices -- Mathematical models , Derivative securities -- Prices -- Mathematical models , Finance -- Mathematical models , Martingales (Mathematics)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5566 , http://hdl.handle.net/10962/d1002804 , Options (Finance) -- Prices -- Mathematical models , Derivative securities -- Prices -- Mathematical models , Finance -- Mathematical models , Martingales (Mathematics)
- Description: American options are the most commonly traded financial derivatives in the market. Pricing these options fairly, so as to avoid arbitrage, is of paramount importance. Closed form solutions for American put options cannot be utilised in practice and so numerical techniques are employed. This thesis looks at the work done by other researchers to find an analytic solution to the American put option pricing problem and suggests a practical method, that uses Monte Carlo simulation, to approximate the American put option price. The theory behind option pricing is first discussed using a discrete model. Once the concepts of arbitrage-free pricing and hedging have been dealt with, this model is extended to a continuous-time setting. Martingale theory is introduced to put the option pricing theory in a more formal framework. The construction of a hedging portfolio is discussed in detail and it is shown how financial derivatives are priced according to a unique riskneutral probability measure. Black-Scholes model is discussed and utilised to find closed form solutions to European style options. American options are discussed in detail and it is shown that under certain conditions, American style options can be solved according to closed form solutions. Various numerical techniques are presented to approximate the true American put option price. Chief among these methods is the Richardson extrapolation on a sequence of Bermudan options method that was developed by Geske and Johnson. This model is extended to a Repeated-Richardson extrapolation technique. Finally, a Monte Carlo simulation is used to approximate Bermudan put options. These values are then extrapolated to approximate the price of an American put option. The use of extrapolation techniques was hampered by the presence of non-uniform convergence of the Bermudan put option sequence. When convergence was uniform, the approximations were accurate up to a few cents difference.
- Full Text:
- Date Issued: 2009
- Authors: Glover, Elistan Nicholas
- Date: 2009
- Subjects: Options (Finance) -- Prices -- Mathematical models , Derivative securities -- Prices -- Mathematical models , Finance -- Mathematical models , Martingales (Mathematics)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5566 , http://hdl.handle.net/10962/d1002804 , Options (Finance) -- Prices -- Mathematical models , Derivative securities -- Prices -- Mathematical models , Finance -- Mathematical models , Martingales (Mathematics)
- Description: American options are the most commonly traded financial derivatives in the market. Pricing these options fairly, so as to avoid arbitrage, is of paramount importance. Closed form solutions for American put options cannot be utilised in practice and so numerical techniques are employed. This thesis looks at the work done by other researchers to find an analytic solution to the American put option pricing problem and suggests a practical method, that uses Monte Carlo simulation, to approximate the American put option price. The theory behind option pricing is first discussed using a discrete model. Once the concepts of arbitrage-free pricing and hedging have been dealt with, this model is extended to a continuous-time setting. Martingale theory is introduced to put the option pricing theory in a more formal framework. The construction of a hedging portfolio is discussed in detail and it is shown how financial derivatives are priced according to a unique riskneutral probability measure. Black-Scholes model is discussed and utilised to find closed form solutions to European style options. American options are discussed in detail and it is shown that under certain conditions, American style options can be solved according to closed form solutions. Various numerical techniques are presented to approximate the true American put option price. Chief among these methods is the Richardson extrapolation on a sequence of Bermudan options method that was developed by Geske and Johnson. This model is extended to a Repeated-Richardson extrapolation technique. Finally, a Monte Carlo simulation is used to approximate Bermudan put options. These values are then extrapolated to approximate the price of an American put option. The use of extrapolation techniques was hampered by the presence of non-uniform convergence of the Bermudan put option sequence. When convergence was uniform, the approximations were accurate up to a few cents difference.
- Full Text:
- Date Issued: 2009
Assessment and monitoring of land degradation using remote sensing and geographic information systems (GIS): a case study of Qoqodala within the Wit-Kei catchment in the Eastern Cape, South Africa
- Ngcofe, Luncedo Dalithemba Sanelisiwe
- Authors: Ngcofe, Luncedo Dalithemba Sanelisiwe
- Date: 2009
- Subjects: Geographic information systems -- South Africa -- Eastern Cape , Remote sensing -- South Africa -- Eastern Cape , Land degradation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4818 , http://hdl.handle.net/10962/d1005492 , Geographic information systems -- South Africa -- Eastern Cape , Remote sensing -- South Africa -- Eastern Cape , Land degradation -- South Africa -- Eastern Cape
- Description: Land degradation is a global problem affecting many countries including South Africa. This study was conducted in order to assess and monitor the nature and extent of land degradation within Qoqodala in the Eastern Cape Province, of South Africa. The study used GIS and Remote Sensing techniques together with household interviews in determining extent, spatial characteristics and nature of land degradation within the study area. Vegetation cover and bare-ground change were the land degradation indicators assessed and monitored by this study. Through RGB band combination, Tasselled Cap Analysis and Unsupervised ISODATA classification techniques, Landsat images over the past eighteen years (1984, 1993, 1996, 2000 and 2002) have been analysed. The results showed that there is vegetation cover and bare-ground increase in the study area. The vegetation increase has been seen as a sign of land degradation increase due to the encroachment of indigenous vegetation by Euryops species (also known as Lapesi by the local community). The bare-ground land degradation indicator has also increased. The analyses of slope showed the spatial characteristics of bare-ground occurring on moderate to flat slopes while vegetation cover occurs on steep to very steep slopes. Furthermore the photographs captured during field visits show rills and gullies or dongas occurring on bare-ground. The interviewed respondents indicated that decline in food production, increase in dongas and vast increase in Euryops and a decline in grassland are the indicators of degradation that are observed in the study area. The occurrence of erosion features (rills and dongas) on bare-ground and the increase of vegetation shown by GIS and Remote Sensing techniques showed a positive correlation with field and household survey towards establishing the nature of land degradation. In this study Landsat images together with interviews proved to be a very useful tool for land degradation research. However the suggestion of a higher spatial resolution satellite image on small catchment studies is recommended
- Full Text:
- Date Issued: 2009
- Authors: Ngcofe, Luncedo Dalithemba Sanelisiwe
- Date: 2009
- Subjects: Geographic information systems -- South Africa -- Eastern Cape , Remote sensing -- South Africa -- Eastern Cape , Land degradation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4818 , http://hdl.handle.net/10962/d1005492 , Geographic information systems -- South Africa -- Eastern Cape , Remote sensing -- South Africa -- Eastern Cape , Land degradation -- South Africa -- Eastern Cape
- Description: Land degradation is a global problem affecting many countries including South Africa. This study was conducted in order to assess and monitor the nature and extent of land degradation within Qoqodala in the Eastern Cape Province, of South Africa. The study used GIS and Remote Sensing techniques together with household interviews in determining extent, spatial characteristics and nature of land degradation within the study area. Vegetation cover and bare-ground change were the land degradation indicators assessed and monitored by this study. Through RGB band combination, Tasselled Cap Analysis and Unsupervised ISODATA classification techniques, Landsat images over the past eighteen years (1984, 1993, 1996, 2000 and 2002) have been analysed. The results showed that there is vegetation cover and bare-ground increase in the study area. The vegetation increase has been seen as a sign of land degradation increase due to the encroachment of indigenous vegetation by Euryops species (also known as Lapesi by the local community). The bare-ground land degradation indicator has also increased. The analyses of slope showed the spatial characteristics of bare-ground occurring on moderate to flat slopes while vegetation cover occurs on steep to very steep slopes. Furthermore the photographs captured during field visits show rills and gullies or dongas occurring on bare-ground. The interviewed respondents indicated that decline in food production, increase in dongas and vast increase in Euryops and a decline in grassland are the indicators of degradation that are observed in the study area. The occurrence of erosion features (rills and dongas) on bare-ground and the increase of vegetation shown by GIS and Remote Sensing techniques showed a positive correlation with field and household survey towards establishing the nature of land degradation. In this study Landsat images together with interviews proved to be a very useful tool for land degradation research. However the suggestion of a higher spatial resolution satellite image on small catchment studies is recommended
- Full Text:
- Date Issued: 2009
Awkward working postures and precision performance as an example of the relationship between ergonomics and production quality
- Ngcamu, Nokubonga Slindele (Sma)
- Authors: Ngcamu, Nokubonga Slindele (Sma)
- Date: 2009
- Subjects: Human engineering , Posture , Posture disorders , Musculoskeletal system -- Diseases , Work -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5105 , http://hdl.handle.net/10962/d1005183 , Human engineering , Posture , Posture disorders , Musculoskeletal system -- Diseases , Work -- Physiological aspects
- Description: Ergonomics aims to improve worker health and enhance productivity and quality. Knowledge and practical evidence of this relationship would be instrumental for optimising organisational performance particularly in industrially developing countries where the discipline is still in its developmental stages. Therefore this thesis set out to analyse the relationship between ergonomics deficiencies and performance. A survey was first conducted to establish the severity of quality problems in the South African manufacturing industry and to determine if these were related to Ergonomic deficiencies. The results indicated that quality problems continue to plague industry, a challenge associated with huge cost implications. Furthermore organisations were not cognisant of the fact that ergonomics deficiencies such as poor workstation design and awkward or constrained working postures are a major contributing factor to poor quality and performance decrements. This demonstrates that much is yet to be done in raising awareness about the benefits of ergonomics in South Africa and other industrially developing countries. However, for this to be effective, tangible evidence of these purported benefits is required. In lieu of this, a laboratory study was then conducted to establish the relationship between awkward working postures and the performance of precision tasks. Acknowledging that the task and the worker are interrelated elements, the impact of precision task demands on the postural strain experienced by the human was also investigated. A high and low precision task quantified positional precision while a force task (combination of pushing and pulling) was utilised to assess the ability to maintain a precise force over time. These three tasks were performed in eight different postures; namely seated, standing, stooping 300 and 600, working overhead, lying supine, and twisting to either side. A combination of the tasks and postures resulted in 24 experimental conditions that were tested on forty eight healthy male and female participants. The performance related dependent variables were movement time, deviation from the centre of the target, and the trend/slope followed by the force exerted. Muscle activity of eight arm, shoulder and back muscles, iii supplemented with heart rate and local ratings of perceived exertion, were utilised to quantify the impact of the tasks and the postures on the individual. The results revealed that awkward working postures do in fact influence performance outcomes. In this regard, awkward working postures (such as overhead work and lying supine and stooping) were evidenced to significantly affect movement time, deviations from the target and the ability to maintain a constant force over time. These variables have a direct relationship with organisational priorities such as productivity and quality. Furthermore, the results indicated that high precision demands augment postural strain elicited through high muscle activity responses and may have negative implications for the precipitation of musculoskeletal disorders. Essentially, the work done on this thesis reflected the complex nature of ergonomics by drawing on both macro and micro-ergonomics approaches. In so doing, challenges perceived to be relevant to industry as reported by organisations formed the foundation for further laboratory studies. Therefore, more collaborative research and knowledge transfer between industry and ergonomics researchers is a necessity particularly in industrially developing countries where ergonomics is still in its developmental stages.
- Full Text:
- Date Issued: 2009
- Authors: Ngcamu, Nokubonga Slindele (Sma)
- Date: 2009
- Subjects: Human engineering , Posture , Posture disorders , Musculoskeletal system -- Diseases , Work -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5105 , http://hdl.handle.net/10962/d1005183 , Human engineering , Posture , Posture disorders , Musculoskeletal system -- Diseases , Work -- Physiological aspects
- Description: Ergonomics aims to improve worker health and enhance productivity and quality. Knowledge and practical evidence of this relationship would be instrumental for optimising organisational performance particularly in industrially developing countries where the discipline is still in its developmental stages. Therefore this thesis set out to analyse the relationship between ergonomics deficiencies and performance. A survey was first conducted to establish the severity of quality problems in the South African manufacturing industry and to determine if these were related to Ergonomic deficiencies. The results indicated that quality problems continue to plague industry, a challenge associated with huge cost implications. Furthermore organisations were not cognisant of the fact that ergonomics deficiencies such as poor workstation design and awkward or constrained working postures are a major contributing factor to poor quality and performance decrements. This demonstrates that much is yet to be done in raising awareness about the benefits of ergonomics in South Africa and other industrially developing countries. However, for this to be effective, tangible evidence of these purported benefits is required. In lieu of this, a laboratory study was then conducted to establish the relationship between awkward working postures and the performance of precision tasks. Acknowledging that the task and the worker are interrelated elements, the impact of precision task demands on the postural strain experienced by the human was also investigated. A high and low precision task quantified positional precision while a force task (combination of pushing and pulling) was utilised to assess the ability to maintain a precise force over time. These three tasks were performed in eight different postures; namely seated, standing, stooping 300 and 600, working overhead, lying supine, and twisting to either side. A combination of the tasks and postures resulted in 24 experimental conditions that were tested on forty eight healthy male and female participants. The performance related dependent variables were movement time, deviation from the centre of the target, and the trend/slope followed by the force exerted. Muscle activity of eight arm, shoulder and back muscles, iii supplemented with heart rate and local ratings of perceived exertion, were utilised to quantify the impact of the tasks and the postures on the individual. The results revealed that awkward working postures do in fact influence performance outcomes. In this regard, awkward working postures (such as overhead work and lying supine and stooping) were evidenced to significantly affect movement time, deviations from the target and the ability to maintain a constant force over time. These variables have a direct relationship with organisational priorities such as productivity and quality. Furthermore, the results indicated that high precision demands augment postural strain elicited through high muscle activity responses and may have negative implications for the precipitation of musculoskeletal disorders. Essentially, the work done on this thesis reflected the complex nature of ergonomics by drawing on both macro and micro-ergonomics approaches. In so doing, challenges perceived to be relevant to industry as reported by organisations formed the foundation for further laboratory studies. Therefore, more collaborative research and knowledge transfer between industry and ergonomics researchers is a necessity particularly in industrially developing countries where ergonomics is still in its developmental stages.
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- Date Issued: 2009