An examination of validation practices in relation to the forensic acquisition of digital evidence in South Africa
- Authors: Jordaan, Jason
- Date: 2014
- Subjects: Electronic evidence , Evidence, Criminal , Forensic sciences , Evidence, Criminal -- South Africa -- Law and legislation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4706 , http://hdl.handle.net/10962/d1016361
- Description: The acquisition of digital evidence is the most crucial part of the entire digital forensics process. During this process, digital evidence is acquired in a forensically sound manner to ensure the legal admissibility and reliability of that evidence in court. In the acquisition process various hardware or software tools are used to acquire the digital evidence. All of the digital forensic standards relating to the acquisition of digital evidence require that the hardware and software tools used in the acquisition process are validated as functioning correctly and reliably, as this lends credibility to the evidence in court. In fact the Electronic Communications and Transactions Act 25 of 2002 in South Africa specifically requires courts to consider issues such as reliability and the manner in which the integrity of digital evidence is ensured when assessing the evidential weight of digital evidence. Previous research into quality assurance in the practice of digital forensics in South Africa identified that in general, tool validation was not performed, and as such a hypothesis was proposed that digital forensic practitioners in South Africa make use of hardware and/or software tools for the forensic acquisition of digital evidence, whose validity and/or reliability cannot be objectively proven. As such the reliability of any digital evidence preserved using those tools is potentially unreliable. This hypothesis was tested in the research through the use of a survey of digital forensic practitioners in South Africa. The research established that the majority of digital forensic practitioners do not use tools in the forensic acquisition of digital evidence that can be proven to be validated and/or reliable. While just under a fifth of digital forensic practitioners can provide some proof of validation and/or reliability, the proof of validation does not meet formal international standards. In essence this means that digital evidence, which is preserved through the use of specific hardware and/or software tools for subsequent presentation and reliance upon as evidence in a court of law, is preserved by tools where the objective and scientific validity thereof has not been determined. Since South African courts must consider reliability in terms of Section 15(3) of the Electronic Communications and Transactions Act 25 of 2002 in assessing the weight of digital evidence, this is undermined through the current state of practice in South Africa by digital forensic practitioners.
- Full Text:
- Date Issued: 2014
- Authors: Jordaan, Jason
- Date: 2014
- Subjects: Electronic evidence , Evidence, Criminal , Forensic sciences , Evidence, Criminal -- South Africa -- Law and legislation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4706 , http://hdl.handle.net/10962/d1016361
- Description: The acquisition of digital evidence is the most crucial part of the entire digital forensics process. During this process, digital evidence is acquired in a forensically sound manner to ensure the legal admissibility and reliability of that evidence in court. In the acquisition process various hardware or software tools are used to acquire the digital evidence. All of the digital forensic standards relating to the acquisition of digital evidence require that the hardware and software tools used in the acquisition process are validated as functioning correctly and reliably, as this lends credibility to the evidence in court. In fact the Electronic Communications and Transactions Act 25 of 2002 in South Africa specifically requires courts to consider issues such as reliability and the manner in which the integrity of digital evidence is ensured when assessing the evidential weight of digital evidence. Previous research into quality assurance in the practice of digital forensics in South Africa identified that in general, tool validation was not performed, and as such a hypothesis was proposed that digital forensic practitioners in South Africa make use of hardware and/or software tools for the forensic acquisition of digital evidence, whose validity and/or reliability cannot be objectively proven. As such the reliability of any digital evidence preserved using those tools is potentially unreliable. This hypothesis was tested in the research through the use of a survey of digital forensic practitioners in South Africa. The research established that the majority of digital forensic practitioners do not use tools in the forensic acquisition of digital evidence that can be proven to be validated and/or reliable. While just under a fifth of digital forensic practitioners can provide some proof of validation and/or reliability, the proof of validation does not meet formal international standards. In essence this means that digital evidence, which is preserved through the use of specific hardware and/or software tools for subsequent presentation and reliance upon as evidence in a court of law, is preserved by tools where the objective and scientific validity thereof has not been determined. Since South African courts must consider reliability in terms of Section 15(3) of the Electronic Communications and Transactions Act 25 of 2002 in assessing the weight of digital evidence, this is undermined through the current state of practice in South Africa by digital forensic practitioners.
- Full Text:
- Date Issued: 2014
An exploration into the use of webinjects by financial malware
- Authors: Forrester, Jock Ingram
- Date: 2014
- Subjects: Malware (Computer software) -- Analysis , Internet fraud , Computer crimes , Computer security , Electronic commerce
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4697 , http://hdl.handle.net/10962/d1012079 , Malware (Computer software) -- Analysis , Internet fraud , Computer crimes , Computer security , Electronic commerce
- Description: As the number of computing devices connected to the Internet increases and the Internet itself becomes more pervasive, so does the opportunity for criminals to use these devices in cybercrimes. Supporting the increase in cybercrime is the growth and maturity of the digital underground economy with strong links to its more visible and physical counterpart. The digital underground economy provides software and related services to equip the entrepreneurial cybercriminal with the appropriate skills and required tools. Financial malware, particularly the capability for injection of code into web browsers, has become one of the more profitable cybercrime tool sets due to its versatility and adaptability when targeting clients of institutions with an online presence, both in and outside of the financial industry. There are numerous families of financial malware available for use, with perhaps the most prevalent being Zeus and SpyEye. Criminals create (or purchase) and grow botnets of computing devices infected with financial malware that has been configured to attack clients of certain websites. In the research data set there are 483 configuration files containing approximately 40 000 webinjects that were captured from various financial malware botnets between October 2010 and June 2012. They were processed and analysed to determine the methods used by criminals to defraud either the user of the computing device, or the institution of which the user is a client. The configuration files contain the injection code that is executed in the web browser to create a surrogate interface, which is then used by the criminal to interact with the user and institution in order to commit fraud. Demographics on the captured data set are presented and case studies are documented based on the various methods used to defraud and bypass financial security controls across multiple industries. The case studies cover techniques used in social engineering, bypassing security controls and automated transfers.
- Full Text:
- Date Issued: 2014
- Authors: Forrester, Jock Ingram
- Date: 2014
- Subjects: Malware (Computer software) -- Analysis , Internet fraud , Computer crimes , Computer security , Electronic commerce
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4697 , http://hdl.handle.net/10962/d1012079 , Malware (Computer software) -- Analysis , Internet fraud , Computer crimes , Computer security , Electronic commerce
- Description: As the number of computing devices connected to the Internet increases and the Internet itself becomes more pervasive, so does the opportunity for criminals to use these devices in cybercrimes. Supporting the increase in cybercrime is the growth and maturity of the digital underground economy with strong links to its more visible and physical counterpart. The digital underground economy provides software and related services to equip the entrepreneurial cybercriminal with the appropriate skills and required tools. Financial malware, particularly the capability for injection of code into web browsers, has become one of the more profitable cybercrime tool sets due to its versatility and adaptability when targeting clients of institutions with an online presence, both in and outside of the financial industry. There are numerous families of financial malware available for use, with perhaps the most prevalent being Zeus and SpyEye. Criminals create (or purchase) and grow botnets of computing devices infected with financial malware that has been configured to attack clients of certain websites. In the research data set there are 483 configuration files containing approximately 40 000 webinjects that were captured from various financial malware botnets between October 2010 and June 2012. They were processed and analysed to determine the methods used by criminals to defraud either the user of the computing device, or the institution of which the user is a client. The configuration files contain the injection code that is executed in the web browser to create a surrogate interface, which is then used by the criminal to interact with the user and institution in order to commit fraud. Demographics on the captured data set are presented and case studies are documented based on the various methods used to defraud and bypass financial security controls across multiple industries. The case studies cover techniques used in social engineering, bypassing security controls and automated transfers.
- Full Text:
- Date Issued: 2014
An investigation into the use of a ceramifiable Ethylene Vinyl Acetate (EVA) co-polymer formulation to aid flame retardency in electrical cables
- Authors: Bambalaza, Sonwabo Elvis
- Date: 2014
- Subjects: Vinyl acetate , Polymeric composites , Inorganic compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10433 , http://hdl.handle.net/10948/d1020159
- Description: The concept of a unique ceramifiable Ethylene vinyl acetate (EVA) based polymer composite was based on the incorporation of inorganic compounds such as aluminium hydroxide, calcium carbonate, muscovite mica, and calcined kaolinite within a 95 percent EVA/ 5 percent Polydimethylsiloxane (PDMS) polymer matrix such tha t upon heating to elevated temperatures of about 1000 oC, a solid end-product with ceramic-like properties would be formed. The ceramifiable EVA based polymer composite was developed to be used as electric cable insulation or sheath as the formation of a ceramic based material at elevated temperatures would provide flame retardant properties during fire situations. The flame retardant properties at elevated temperatures would ensure that the insulation remains at such temperatures due to some of the properties of the resultant ceramic such as reasonably high flexural strength, high thermal stability, non-reactivity and high melting point. During a fire this would ensure that flames would not be propagated along the length of the cable and also protect the underlying conducting wires from being exposed to the high temperatures of the fire. Its application as a cable insulation also required that the material functions as a cable insulator under ambient temperature conditions where the ceramifiable polymer composite should retain certain polymer properties such as the post-cure tensile strength (MPa), degree of polymer elongation (percent), thermal expansion, thermal slacking, limited oxygen index and electrical insulation. This study made use of a composite experimental design approach that would allow for the optimization of the amounts of the additives in the ceramifiable polymer composite giving both the desired mechanical properties of the material under normal operating temperatures as a polymer and also as a ceramic once exposed to elevated temperatures. The optimization of additives used in the ceramifiable polymer composite was done by using a D-optimal mixture design of experiments (DoE) which was analyzed by multiple linear regression.
- Full Text:
- Date Issued: 2014
- Authors: Bambalaza, Sonwabo Elvis
- Date: 2014
- Subjects: Vinyl acetate , Polymeric composites , Inorganic compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10433 , http://hdl.handle.net/10948/d1020159
- Description: The concept of a unique ceramifiable Ethylene vinyl acetate (EVA) based polymer composite was based on the incorporation of inorganic compounds such as aluminium hydroxide, calcium carbonate, muscovite mica, and calcined kaolinite within a 95 percent EVA/ 5 percent Polydimethylsiloxane (PDMS) polymer matrix such tha t upon heating to elevated temperatures of about 1000 oC, a solid end-product with ceramic-like properties would be formed. The ceramifiable EVA based polymer composite was developed to be used as electric cable insulation or sheath as the formation of a ceramic based material at elevated temperatures would provide flame retardant properties during fire situations. The flame retardant properties at elevated temperatures would ensure that the insulation remains at such temperatures due to some of the properties of the resultant ceramic such as reasonably high flexural strength, high thermal stability, non-reactivity and high melting point. During a fire this would ensure that flames would not be propagated along the length of the cable and also protect the underlying conducting wires from being exposed to the high temperatures of the fire. Its application as a cable insulation also required that the material functions as a cable insulator under ambient temperature conditions where the ceramifiable polymer composite should retain certain polymer properties such as the post-cure tensile strength (MPa), degree of polymer elongation (percent), thermal expansion, thermal slacking, limited oxygen index and electrical insulation. This study made use of a composite experimental design approach that would allow for the optimization of the amounts of the additives in the ceramifiable polymer composite giving both the desired mechanical properties of the material under normal operating temperatures as a polymer and also as a ceramic once exposed to elevated temperatures. The optimization of additives used in the ceramifiable polymer composite was done by using a D-optimal mixture design of experiments (DoE) which was analyzed by multiple linear regression.
- Full Text:
- Date Issued: 2014
An investigation of the potential anti-diabetic (insulinomimetic) activity of anti-oxidant compounds derived from Sargassum heterophyllum
- Authors: Nyambe, Mutenta Nsokolo
- Date: 2014
- Subjects: Sargassum , Diabetes -- Chemotherapy , Diabetes -- Africa , Antioxidants -- Therapeutic use , Marine algae , Endemic plants -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3874 , http://hdl.handle.net/10962/d1021020
- Description: In Africa, non-communicable diseases such as diabetes mellitus have been generally neglected. This problem has worsened over the years owing to continuous threats from infectious diseases such as HIV/AIDS, tuberculosis and malaria. Despite this, statistics have shown that by 2030, the African region will have the highest proportional increase in diabetes prevalence. Over 80% of all diabetic deaths occur in developing countries probably not only due to poor equity of access to medication but also due to limited efficacy and side effects associated with the commonly available anti-diabetic agents. Therefore, this creates the desperate need for the development of new anti-diabetic agents that are more efficacious and can be sourced from within the continent. With oxidative stress as a suggested mechanism underlying the cause of diabetes mellitus and diabetic complications, the discovery of natural anti-oxidants that prevent free radical mediated damage is important for developing new treatment strategies. Marine algae have been identified as good sources for natural anti-oxidants. Unfortunately, very few studies have embarked on the discovery of marine-derived anti-oxidant compounds with potential anti-diabetic activity. In this project, we investigated the potential anti-oxidant activity of the South African endemic algae Stypopodium multipartitum, Dictyopterus ligulata, Cystophora fibriosa, Bifurcariopsis capensis, Sargassum sp. and Sargassum heterophyllum. From these studies, Sargassum heterophyllum yielded prenylated compounds, the main compound being sargahydroquinoic acid (3.6) and the carotenoid metabolite fucoxanthin (3.8), which are in part responsible for the radical scavenging activity of the crude extract. Sargahydroquinoic acid (3.6) and fucoxanthin (3.8) also exhibited significant anti-inflammatory activity. Sargaquinoic acid (3.1), sargachromenoic acid (3.9) and sarganaphthoquinoic acid (3.10) were then semi-synthesized from sargahydroquinoic acid (3.6) and their in-vitro cytotoxicity profiles evaluated using Chang Liver, HT-29, Caco-2 and 3T3-L1 cell lines prior to antidiabetic testing. From the semi-synthetic derivatives, sargachromenoic acid (3.9) exhibited the most potent anti-oxidant activity (IC₅₀ = 6.99 μg/mL). After the evaluation of antidiabetic activity using 3T3-L1 preadipocyte differentiation, sarganaphthoquinoic acid (3.10) showed the most potent insulinomimetic activity at 1.19 μM by inducing a PPARγ response similar to that of rosiglitazone at 1 μM.
- Full Text:
- Date Issued: 2014
- Authors: Nyambe, Mutenta Nsokolo
- Date: 2014
- Subjects: Sargassum , Diabetes -- Chemotherapy , Diabetes -- Africa , Antioxidants -- Therapeutic use , Marine algae , Endemic plants -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3874 , http://hdl.handle.net/10962/d1021020
- Description: In Africa, non-communicable diseases such as diabetes mellitus have been generally neglected. This problem has worsened over the years owing to continuous threats from infectious diseases such as HIV/AIDS, tuberculosis and malaria. Despite this, statistics have shown that by 2030, the African region will have the highest proportional increase in diabetes prevalence. Over 80% of all diabetic deaths occur in developing countries probably not only due to poor equity of access to medication but also due to limited efficacy and side effects associated with the commonly available anti-diabetic agents. Therefore, this creates the desperate need for the development of new anti-diabetic agents that are more efficacious and can be sourced from within the continent. With oxidative stress as a suggested mechanism underlying the cause of diabetes mellitus and diabetic complications, the discovery of natural anti-oxidants that prevent free radical mediated damage is important for developing new treatment strategies. Marine algae have been identified as good sources for natural anti-oxidants. Unfortunately, very few studies have embarked on the discovery of marine-derived anti-oxidant compounds with potential anti-diabetic activity. In this project, we investigated the potential anti-oxidant activity of the South African endemic algae Stypopodium multipartitum, Dictyopterus ligulata, Cystophora fibriosa, Bifurcariopsis capensis, Sargassum sp. and Sargassum heterophyllum. From these studies, Sargassum heterophyllum yielded prenylated compounds, the main compound being sargahydroquinoic acid (3.6) and the carotenoid metabolite fucoxanthin (3.8), which are in part responsible for the radical scavenging activity of the crude extract. Sargahydroquinoic acid (3.6) and fucoxanthin (3.8) also exhibited significant anti-inflammatory activity. Sargaquinoic acid (3.1), sargachromenoic acid (3.9) and sarganaphthoquinoic acid (3.10) were then semi-synthesized from sargahydroquinoic acid (3.6) and their in-vitro cytotoxicity profiles evaluated using Chang Liver, HT-29, Caco-2 and 3T3-L1 cell lines prior to antidiabetic testing. From the semi-synthetic derivatives, sargachromenoic acid (3.9) exhibited the most potent anti-oxidant activity (IC₅₀ = 6.99 μg/mL). After the evaluation of antidiabetic activity using 3T3-L1 preadipocyte differentiation, sarganaphthoquinoic acid (3.10) showed the most potent insulinomimetic activity at 1.19 μM by inducing a PPARγ response similar to that of rosiglitazone at 1 μM.
- Full Text:
- Date Issued: 2014
An investigation of the role of mitochondrial STAT3 and modulation of Reactive Oxygen Species in adipocyte differentiation
- Authors: Kramer, Adam Hildyard
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54632 , vital:26595
- Description: Stem cells have the ability to differentiate into a myriad of different cell types. The understanding of the differentiation process is of paramount importance if we are to use these cells in the lab as well as in therapeutics. Here, the levels and localization of the signal transducer and activator of transcription 3 (STAT3), with particular attention focused on the mitochondrial serine 727 phosphorylated form of STAT3 (pSTAT3S727) during differentiation, was investigated. Using the murine preadipocyte progenitor cell line 3T3-L1, as well as adipose derived human mesenchymal stem cells (HMSC-ad) as differentiation models, the relative levels of Reactive Oxygen Species (ROS) and the levels and localization of STAT3 were investigated during the differentiation process. ROS is known to play an important signalling role during differentiation and is well reported during the events of adipogenesis. ROS are generated as a by-product in the Electron Transport Chain (ETC), and it has recently been reported that pSTAT3S727 plays an important role at complex I of the ETC. Various techniques including fluorescence confocal microscopy, flow cytometry and Western blots were utilized to investigate the non-canonical role STAT3 plays during adipogenesis. Mitochondrial isolations were performed to investigate the levels of STAT3 in the mitochondria during differentiation. Further to this, an impedance based real time differentiation assay was developed using the xCELLigence Real Time Cell Analyser to monitor differentiation and the affects various compounds, including a STAT3 inhibitor, have on differentiation. Results indicate that upon induction of differentiation, levels of mitochondrial pSTAT3S727 dramatically decrease and leave the mitochondria. This corresponds to increasing levels of ROS. The canonical active form of STAT3 following phosphorylation on tyrosine 705 (pSTAT3Y705) was found to decrease and lose its nuclear localization. These initial results indicate that STAT3 plays an important non-canonical role in the mitochondria during differentiation.
- Full Text:
- Date Issued: 2014
- Authors: Kramer, Adam Hildyard
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54632 , vital:26595
- Description: Stem cells have the ability to differentiate into a myriad of different cell types. The understanding of the differentiation process is of paramount importance if we are to use these cells in the lab as well as in therapeutics. Here, the levels and localization of the signal transducer and activator of transcription 3 (STAT3), with particular attention focused on the mitochondrial serine 727 phosphorylated form of STAT3 (pSTAT3S727) during differentiation, was investigated. Using the murine preadipocyte progenitor cell line 3T3-L1, as well as adipose derived human mesenchymal stem cells (HMSC-ad) as differentiation models, the relative levels of Reactive Oxygen Species (ROS) and the levels and localization of STAT3 were investigated during the differentiation process. ROS is known to play an important signalling role during differentiation and is well reported during the events of adipogenesis. ROS are generated as a by-product in the Electron Transport Chain (ETC), and it has recently been reported that pSTAT3S727 plays an important role at complex I of the ETC. Various techniques including fluorescence confocal microscopy, flow cytometry and Western blots were utilized to investigate the non-canonical role STAT3 plays during adipogenesis. Mitochondrial isolations were performed to investigate the levels of STAT3 in the mitochondria during differentiation. Further to this, an impedance based real time differentiation assay was developed using the xCELLigence Real Time Cell Analyser to monitor differentiation and the affects various compounds, including a STAT3 inhibitor, have on differentiation. Results indicate that upon induction of differentiation, levels of mitochondrial pSTAT3S727 dramatically decrease and leave the mitochondria. This corresponds to increasing levels of ROS. The canonical active form of STAT3 following phosphorylation on tyrosine 705 (pSTAT3Y705) was found to decrease and lose its nuclear localization. These initial results indicate that STAT3 plays an important non-canonical role in the mitochondria during differentiation.
- Full Text:
- Date Issued: 2014
An investigation of the XMOS XSl architecture as a platform for development of audio control standards
- Authors: Dibley, James
- Date: 2014
- Subjects: Microcontrollers -- Research , Streaming audio -- Standards -- Research , Computer sound processing -- Research , Computer network protocols -- Standards -- Research , Communication -- Technological innovations -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4694 , http://hdl.handle.net/10962/d1011789 , Microcontrollers -- Research , Streaming audio -- Standards -- Research , Computer sound processing -- Research , Computer network protocols -- Standards -- Research , Communication -- Technological innovations -- Research
- Description: This thesis investigates the feasiblity of using a new microcontroller architecture, the XMOS XS1, in the research and development of control standards for audio distribution networks. This investigation is conducted in the context of an emerging audio distribution network standard, Ethernet Audio/Video Bridging (`Ethernet AVB'), and an emerging audio control standard, AES-64. The thesis describes these emerging standards, the XMOS XS1 architecture (including its associated programming language, XC), and the open-source implementation of an Ethernet AVB streaming audio device based on the XMOS XS1 architecture. It is shown how the XMOS XS1 architecture and its associated features, focusing on the XC language's mechanisms for concurrency, event-driven programming, and integration of C software modules, enable a powerful implementation of the AES-64 control standard. Feasibility is demonstrated by the implementation of an AES-64 protocol stack and its integration into an XMOS XS1-based Ethernet AVB streaming audio device, providing control of Ethernet AVB features and audio hardware, as well as implementations of advanced AES-64 control mechanisms. It is demonstrated that the XMOS XS1 architecture is a compelling platform for the development of audio control standards, and has enabled the implementation of AES-64 connection management and control over standards-compliant Ethernet AVB streaming audio devices where no such implementation previously existed. The research additionally describes a linear design method for applications based on the XMOS XS1 architecture, and provides a baseline implementation reference for the AES-64 control standard where none previously existed.
- Full Text:
- Date Issued: 2014
- Authors: Dibley, James
- Date: 2014
- Subjects: Microcontrollers -- Research , Streaming audio -- Standards -- Research , Computer sound processing -- Research , Computer network protocols -- Standards -- Research , Communication -- Technological innovations -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4694 , http://hdl.handle.net/10962/d1011789 , Microcontrollers -- Research , Streaming audio -- Standards -- Research , Computer sound processing -- Research , Computer network protocols -- Standards -- Research , Communication -- Technological innovations -- Research
- Description: This thesis investigates the feasiblity of using a new microcontroller architecture, the XMOS XS1, in the research and development of control standards for audio distribution networks. This investigation is conducted in the context of an emerging audio distribution network standard, Ethernet Audio/Video Bridging (`Ethernet AVB'), and an emerging audio control standard, AES-64. The thesis describes these emerging standards, the XMOS XS1 architecture (including its associated programming language, XC), and the open-source implementation of an Ethernet AVB streaming audio device based on the XMOS XS1 architecture. It is shown how the XMOS XS1 architecture and its associated features, focusing on the XC language's mechanisms for concurrency, event-driven programming, and integration of C software modules, enable a powerful implementation of the AES-64 control standard. Feasibility is demonstrated by the implementation of an AES-64 protocol stack and its integration into an XMOS XS1-based Ethernet AVB streaming audio device, providing control of Ethernet AVB features and audio hardware, as well as implementations of advanced AES-64 control mechanisms. It is demonstrated that the XMOS XS1 architecture is a compelling platform for the development of audio control standards, and has enabled the implementation of AES-64 connection management and control over standards-compliant Ethernet AVB streaming audio devices where no such implementation previously existed. The research additionally describes a linear design method for applications based on the XMOS XS1 architecture, and provides a baseline implementation reference for the AES-64 control standard where none previously existed.
- Full Text:
- Date Issued: 2014
An investigation on the role of Development Finance Institutions (DFI) in building small emerging enterprises for property development initiatives in South Africa
- Authors: Noholoza, Alex
- Date: 2014
- Subjects: Real estate development -- South Africa -- Finance , Entrepreneurship -- South Africa , Small business -- South Africa -- Finance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9714 , http://hdl.handle.net/10948/d1020646
- Description: Purpose of this treatise: The aim of this treatise is to identify the challenges facing emerging entrepreneurs in accessing funding for property development initiatives which results in high levels of declined loans thereby limiting participation in the property market as well as the interventions necessary to improve access to finance. Design / methodology / approach: The questionnaires were emailed to funding institutions and emerging property developers. The questionnaire investigates the respondents‟ perception of importance and evidence of questions on property development, finance and managerial skills drawn from the literature. Findings: The findings of this study are consistent with and support the findings of previous local and international literature on constraints that SME‟s have in accessing finance for various initiatives. The findings indicate that the emerging property developers in South Africa are characterised by insufficient number in representation in the property sector, high risk averse financial institutions that requires collateral to lend. The findings of the study indicate that broader and bolder initiatives aimed at improving the emerging property developer's representation in the market needs a holistic and collaborative approach from the various institutions to aide these entrepreneurs. Value of paper: The research is of importance to all stakeholders involved in the property sector, financial institutions and economic development of the SME sector. The results of the study will contribute to the understanding of the current financing limitations facing SMEs and will assist funding institutions to better understand the role and importance of effective collaboration in improving access to finance to emerging property developers.
- Full Text:
- Date Issued: 2014
- Authors: Noholoza, Alex
- Date: 2014
- Subjects: Real estate development -- South Africa -- Finance , Entrepreneurship -- South Africa , Small business -- South Africa -- Finance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9714 , http://hdl.handle.net/10948/d1020646
- Description: Purpose of this treatise: The aim of this treatise is to identify the challenges facing emerging entrepreneurs in accessing funding for property development initiatives which results in high levels of declined loans thereby limiting participation in the property market as well as the interventions necessary to improve access to finance. Design / methodology / approach: The questionnaires were emailed to funding institutions and emerging property developers. The questionnaire investigates the respondents‟ perception of importance and evidence of questions on property development, finance and managerial skills drawn from the literature. Findings: The findings of this study are consistent with and support the findings of previous local and international literature on constraints that SME‟s have in accessing finance for various initiatives. The findings indicate that the emerging property developers in South Africa are characterised by insufficient number in representation in the property sector, high risk averse financial institutions that requires collateral to lend. The findings of the study indicate that broader and bolder initiatives aimed at improving the emerging property developer's representation in the market needs a holistic and collaborative approach from the various institutions to aide these entrepreneurs. Value of paper: The research is of importance to all stakeholders involved in the property sector, financial institutions and economic development of the SME sector. The results of the study will contribute to the understanding of the current financing limitations facing SMEs and will assist funding institutions to better understand the role and importance of effective collaboration in improving access to finance to emerging property developers.
- Full Text:
- Date Issued: 2014
Analysis of the interaction between recombinant human Beta2 integrin I-domains and CD23
- Authors: Sprong, Kaitlin
- Date: 2014
- Subjects: Immune response -- Regulation , Immunoglobulins , CD23 antigen
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10362 , http://hdl.handle.net/10948/d1021078
- Description: In order to further elucidate the interaction between CD23 and β2 integrins (CD11b/CD18) the following objectives were established: Expression and purification of CD11b I-domain as a GST-fusion protein using Escherichia coli; Cloning, synthesis and expression of CD18 I-Like domain.CD11b I-domain has previously been expressed as a GST-fusion protein (Daniels, 2010) and consequently led to comparable expression of CD18 I-like domain as a GST-fusion protein; Preparation of two site-directed mutants of CD18 I-Like domain in order to study the function of the serine residue involved in the S116P mutation. The serine was mutated to proline, as in LAD patients, as well as alanine, a non-polar alternative, in order to contrast and compare binding characteristics. Expression, refolding and purification of sCD23, and a double mutatedsCD23 (RKΔAA) from E. coli; This was performed according to the method described by Daniels et al. (2005); Investigation of the CD23-CD11b I-like domain interaction through surface plasmon resonance spectroscopy.
- Full Text:
- Date Issued: 2014
- Authors: Sprong, Kaitlin
- Date: 2014
- Subjects: Immune response -- Regulation , Immunoglobulins , CD23 antigen
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10362 , http://hdl.handle.net/10948/d1021078
- Description: In order to further elucidate the interaction between CD23 and β2 integrins (CD11b/CD18) the following objectives were established: Expression and purification of CD11b I-domain as a GST-fusion protein using Escherichia coli; Cloning, synthesis and expression of CD18 I-Like domain.CD11b I-domain has previously been expressed as a GST-fusion protein (Daniels, 2010) and consequently led to comparable expression of CD18 I-like domain as a GST-fusion protein; Preparation of two site-directed mutants of CD18 I-Like domain in order to study the function of the serine residue involved in the S116P mutation. The serine was mutated to proline, as in LAD patients, as well as alanine, a non-polar alternative, in order to contrast and compare binding characteristics. Expression, refolding and purification of sCD23, and a double mutatedsCD23 (RKΔAA) from E. coli; This was performed according to the method described by Daniels et al. (2005); Investigation of the CD23-CD11b I-like domain interaction through surface plasmon resonance spectroscopy.
- Full Text:
- Date Issued: 2014
Analysis of the interaction of Hsp90 with the extracellular matrix protein fibronectin (FN)
- Authors: Hunter, Morgan Campbell
- Date: 2014
- Subjects: Heat shock proteins , Fibronectins , Extracellular matrix proteins , Breast -- Cancer
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4170 , http://hdl.handle.net/10962/d1020960
- Description: Mounting evidence suggests that Hsp90 is present and functionally active in the extracellular space. The biological function of extracellular Hsp90 (eHsp90) remains relatively uncharacterized compared to that of intracellular Hsp90. eHsp90 has been shown to interact with a finite number of extracellular proteins, however, despite the identification of eHsp90 interacting proteins, the function of eHsp90 in these complexes is unknown. Several reports suggest a role for eHsp90α in cell migration and invasion. Reported targets for eHsp90 stimulated cell migration include MMPs, LRP-1, tyrosine kinase receptors and possible others unidentified. Limited studies report a role for eHsp90β. Recently, Hsp90α and Hsp90β were isolated in a complex containing fibronectin (FN) on the surface of MDA-MB-231 breast cancer cells. Herein, we report direct binding of Hsp90α and Hsp90β to FN using a solid phase binding assay and surface plasmon resonance (SPR) spectroscopy. SPR spectroscopy showed that Hsp90β bound the 70 kDa amino-terminal fragment of FN (FN70), but that binding of FN to Hsp90β was not limited to FN70. Confocal microscopy showed regions of colocalization of Hsp90 with extracellular FN matrix fibrils in Hs578T breast cancer cell lines. Treatment of Hs578T breast cancer cells with novobiocin (an Hsp90 inhibitor) and an LRP-1 blocking antibody resulted in a loss of FN matrix and FN endocytosis (novobiocin treated). Addition of exogenous Hsp90β was able to recover such effect after both treatments. FN was shown to colocalize with intracellular LRP-1 in novobiocin treated Hs578T cells. Immunoprecipitation of an LRP-1 containing complex showed the presence of Hsp90 and 70 and 120+ kDa FN fragments. Treatment of Hs578T cells with novobiocin increased the level of FN120+ bound in LRP-1 immunoprecipitate. Exogenous Hsp90β decreased the level of low and high molecular weight FN fragments in a complex with LRP-1, despite the fact that higher levels of lower molecular weight FN fragments were detected in this cell lysate compared to the other treatments. We report FN as a novel interacting protein of eHsp90. Taken together, we provide evidence for a direct role of eHsp90β in FN matrix remodeling. We suggest that Hsp90 plays a direct role in FN matrix dynamics through interaction with FN and LRP-1. The identification of FN as a novel interacting protein of eHsp90 suggests a role for Hsp90 in FN matrix remodeling, which is important for a number of fundamental cellular processes including cell migration and metastasis.
- Full Text:
- Date Issued: 2014
- Authors: Hunter, Morgan Campbell
- Date: 2014
- Subjects: Heat shock proteins , Fibronectins , Extracellular matrix proteins , Breast -- Cancer
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4170 , http://hdl.handle.net/10962/d1020960
- Description: Mounting evidence suggests that Hsp90 is present and functionally active in the extracellular space. The biological function of extracellular Hsp90 (eHsp90) remains relatively uncharacterized compared to that of intracellular Hsp90. eHsp90 has been shown to interact with a finite number of extracellular proteins, however, despite the identification of eHsp90 interacting proteins, the function of eHsp90 in these complexes is unknown. Several reports suggest a role for eHsp90α in cell migration and invasion. Reported targets for eHsp90 stimulated cell migration include MMPs, LRP-1, tyrosine kinase receptors and possible others unidentified. Limited studies report a role for eHsp90β. Recently, Hsp90α and Hsp90β were isolated in a complex containing fibronectin (FN) on the surface of MDA-MB-231 breast cancer cells. Herein, we report direct binding of Hsp90α and Hsp90β to FN using a solid phase binding assay and surface plasmon resonance (SPR) spectroscopy. SPR spectroscopy showed that Hsp90β bound the 70 kDa amino-terminal fragment of FN (FN70), but that binding of FN to Hsp90β was not limited to FN70. Confocal microscopy showed regions of colocalization of Hsp90 with extracellular FN matrix fibrils in Hs578T breast cancer cell lines. Treatment of Hs578T breast cancer cells with novobiocin (an Hsp90 inhibitor) and an LRP-1 blocking antibody resulted in a loss of FN matrix and FN endocytosis (novobiocin treated). Addition of exogenous Hsp90β was able to recover such effect after both treatments. FN was shown to colocalize with intracellular LRP-1 in novobiocin treated Hs578T cells. Immunoprecipitation of an LRP-1 containing complex showed the presence of Hsp90 and 70 and 120+ kDa FN fragments. Treatment of Hs578T cells with novobiocin increased the level of FN120+ bound in LRP-1 immunoprecipitate. Exogenous Hsp90β decreased the level of low and high molecular weight FN fragments in a complex with LRP-1, despite the fact that higher levels of lower molecular weight FN fragments were detected in this cell lysate compared to the other treatments. We report FN as a novel interacting protein of eHsp90. Taken together, we provide evidence for a direct role of eHsp90β in FN matrix remodeling. We suggest that Hsp90 plays a direct role in FN matrix dynamics through interaction with FN and LRP-1. The identification of FN as a novel interacting protein of eHsp90 suggests a role for Hsp90 in FN matrix remodeling, which is important for a number of fundamental cellular processes including cell migration and metastasis.
- Full Text:
- Date Issued: 2014
Analysis of the tectonic and basin evolution of the seychelles microcontinent during the mesozoic to cenozoic, based on seismic and well data
- Authors: Mondon, Jean-Luc Andre
- Date: 2014
- Subjects: Sedimentation and deposition , Gondwana (Continent) , Sedimentary basins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/4386 , vital:20593
- Description: The Seychelles Microcontinent (SMc) is a fragment of continental lithosphere that experienced multiple phases of rifting and thermal subsidence during its isolation and submergence within the Indian Ocean. Originally part of central Gondwana, along with India and Madagascar, the SMc first emerged during Mesozoic fragmentation of Gondwana (ca. 220 – 180 Ma) along a complex rifted margin. Fragmentation involved three major rift phases, viz.: 1) Middle Triassic – Middle Jurassic (Rift I), associated with the “Karoo rifts” and break-up between [India-Madagascar-Seychelles] and East Africa; 2) Middle Jurassic – Early Cretaceous (Rift II), associated with the rifting and break-up of Madagascar from [India-Seychelles]; 3) Late Cretaceous (Rift III), associated with the rifting and final break-away of the SMc from India. In this study, the tectonic and sedimentary history of the SMc is analysed using 2D seismic reflection datasets and three exploration wells. Seismic to well-log correlations provide a chrono-stratigraphic framework that identifies seven sequences from the Middle Triassic to the Paleogene. This also identified horst and graben structures related to the extensional tectonics and thermal subsidence of this continental fragment. The latter is reflected also in changes of its litho-facies preserved on the SMc, from terrestrial to marine. The oldest sedimentary rocks identified on the SMc are Middle Triassic organic rich claystones (Sequence 7, Rift I), which grade upwards into alternating Upper Triassic sandstones and mudstones (Sequence 6, Rift I) followed by upward coarsening Lower Jurassic mudstones to sandstone units (Sequence 5, Rift I). These sequences are interpreted as lacustrine facies that evolved into fluvial channel migration facies and finally into progradational delta front facies. Sequence 5 is overlain by Middle Jurassic oolitic limestones that grade upwards into organic rich mudstones (Sequence 4, thermal subsidence after Rift I); the latter are interpreted as restricted-marginal marine deposits. Following Sequence 4, separated by a major break-up unconformity (BU), are the Upper Cretaceous open marine deposits comprising limestones, claystones and sandstones, and terminated with basaltic volcanics (ca. 66 Ma) prior to the separation of the SMc from India (Sequence 3, Rift III). This is overlain by the post-rift – thermal subsidence sequences comprising open marine claystones and shelf limestones (Sequence 2) followed by a sequence of shelf limestones (Sequence 1) that form the present carbonate platform, the Seychelles Plateau that lies approximately 200 m below the present sea-level. Backstripping and subsidence analysis quantifies 3 stages of subsidence; Phase A: Slow subsidence (ca. 5-20 m/Ma), from the Middle Jurassic to the Upper Cretaceous that terminated during a major marine transgression during ingression of the Tethys Sea between East Africa and [Madagascar-Seychelles-India]. This created marine conditions and the subsequent deposition of Sequences 4 and 3; Phase B: Accelerated subsidence (ca. 35-60 m/Ma) recorded throughout the Paleocene to the middle Eocene leading to deeper marine conditions and the subsequent deposition of Sequence 2; and Phase C: Reduced subsidence (ca. 10-30 m/Ma) following the interaction between the Carlsberg Ridge and the Reunion hotspot (ca. 55 Ma) that possibly introduced a reduction in subsidence and the subsequent deposition of Sequence 1 as the SMc drifted and thermally subsided to its submerged present location, and is now dominated mainly by marine carbonates. The effects of the Madagascar and Seychelles/India separation (ca. 84 Ma) are not observed in the subsidence analysis, possibly because it involved transcurrent-rotational movement between the two plates over a short period of time.
- Full Text:
- Date Issued: 2014
- Authors: Mondon, Jean-Luc Andre
- Date: 2014
- Subjects: Sedimentation and deposition , Gondwana (Continent) , Sedimentary basins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/4386 , vital:20593
- Description: The Seychelles Microcontinent (SMc) is a fragment of continental lithosphere that experienced multiple phases of rifting and thermal subsidence during its isolation and submergence within the Indian Ocean. Originally part of central Gondwana, along with India and Madagascar, the SMc first emerged during Mesozoic fragmentation of Gondwana (ca. 220 – 180 Ma) along a complex rifted margin. Fragmentation involved three major rift phases, viz.: 1) Middle Triassic – Middle Jurassic (Rift I), associated with the “Karoo rifts” and break-up between [India-Madagascar-Seychelles] and East Africa; 2) Middle Jurassic – Early Cretaceous (Rift II), associated with the rifting and break-up of Madagascar from [India-Seychelles]; 3) Late Cretaceous (Rift III), associated with the rifting and final break-away of the SMc from India. In this study, the tectonic and sedimentary history of the SMc is analysed using 2D seismic reflection datasets and three exploration wells. Seismic to well-log correlations provide a chrono-stratigraphic framework that identifies seven sequences from the Middle Triassic to the Paleogene. This also identified horst and graben structures related to the extensional tectonics and thermal subsidence of this continental fragment. The latter is reflected also in changes of its litho-facies preserved on the SMc, from terrestrial to marine. The oldest sedimentary rocks identified on the SMc are Middle Triassic organic rich claystones (Sequence 7, Rift I), which grade upwards into alternating Upper Triassic sandstones and mudstones (Sequence 6, Rift I) followed by upward coarsening Lower Jurassic mudstones to sandstone units (Sequence 5, Rift I). These sequences are interpreted as lacustrine facies that evolved into fluvial channel migration facies and finally into progradational delta front facies. Sequence 5 is overlain by Middle Jurassic oolitic limestones that grade upwards into organic rich mudstones (Sequence 4, thermal subsidence after Rift I); the latter are interpreted as restricted-marginal marine deposits. Following Sequence 4, separated by a major break-up unconformity (BU), are the Upper Cretaceous open marine deposits comprising limestones, claystones and sandstones, and terminated with basaltic volcanics (ca. 66 Ma) prior to the separation of the SMc from India (Sequence 3, Rift III). This is overlain by the post-rift – thermal subsidence sequences comprising open marine claystones and shelf limestones (Sequence 2) followed by a sequence of shelf limestones (Sequence 1) that form the present carbonate platform, the Seychelles Plateau that lies approximately 200 m below the present sea-level. Backstripping and subsidence analysis quantifies 3 stages of subsidence; Phase A: Slow subsidence (ca. 5-20 m/Ma), from the Middle Jurassic to the Upper Cretaceous that terminated during a major marine transgression during ingression of the Tethys Sea between East Africa and [Madagascar-Seychelles-India]. This created marine conditions and the subsequent deposition of Sequences 4 and 3; Phase B: Accelerated subsidence (ca. 35-60 m/Ma) recorded throughout the Paleocene to the middle Eocene leading to deeper marine conditions and the subsequent deposition of Sequence 2; and Phase C: Reduced subsidence (ca. 10-30 m/Ma) following the interaction between the Carlsberg Ridge and the Reunion hotspot (ca. 55 Ma) that possibly introduced a reduction in subsidence and the subsequent deposition of Sequence 1 as the SMc drifted and thermally subsided to its submerged present location, and is now dominated mainly by marine carbonates. The effects of the Madagascar and Seychelles/India separation (ca. 84 Ma) are not observed in the subsidence analysis, possibly because it involved transcurrent-rotational movement between the two plates over a short period of time.
- Full Text:
- Date Issued: 2014
Analysis of transcription factor binding specificity using ChIP-seq data.
- Authors: Kibet, Caleb Kipkurui
- Date: 2014
- Subjects: Transcription factors , Chronic myeloid leukemia , Antioncogenes , Cancer cells -- Growth -- Regulation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4115 , http://hdl.handle.net/10962/d1013131
- Description: Transcription factors (TFs) are key regulators of gene expression whose failure has been implicated in many diseases, including cancer. They bind at various sites at different specificity depending on the prevailing cellular conditions, disease, development stage or environmental conditions of the cell. TF binding specificity is how well a TF distinguishes functional sites from potential non-functional sites to form a useful regulatory network. Owing to its role in diseases, various techniques have been used to determine TF binding specificity in vitro and in vivo, including chromatin immuno-precipitation followed by massively parallel sequencing (ChIP-seq). ChIP-seq is an in vivo technique that considers how the chromatin landscape affects TF binding. Motif enrichment analysis (MEA) tools are used to identify motifs that are over-represented in ChIP-seq peak regions. One such tool, CentriMo, finds over-represented motifs at the center since peak calling software are biased to declaring binding regions centered at the TF binding site. In this study, we investigate the use of CentriMo and other MEA tools to determine the difference in motif enrichment attributed presence of Chronic Myeloid leukemia (CML)), treatment with Interferon (IFN) and Dexamethasone (DEX) compared to control based on Fisher’s exact test; using uniform peaks ChIP-seq data generated by the ENCODE consortium. CentriMo proved to be capable. We observed differential motif enrichment of TFs with tumor promoter activity: YY1, CEBPA, Egr1, Cmyc family, Gata1 and JunD in K562 while Stat1, Irf1, and Runx1 in Gm12878. Enrichment of CTCF in Gm12878 with YY1 as the immuno-precipitated (ChIP-ed) factor and the presence of significant spacing (SpaMo analysis) of CTCF and YY1 in Gm12878 but not in K562 could show that CTCF, as a repressor, helps in maintaining the required YY1 level in a normal cell line. IFN might reduce Cmyc and the Jun family of TFs binding via the repressive action of CTCF and E2f2. We also show that the concentration of DEX treatment affects motif enrichment with 50nm being an optimum concentration for Gr binding by maintaining open chromatin via AP1 TF. This study has demonstrated the usefulness of CentriMo for TF binding specificity analysis.
- Full Text:
- Date Issued: 2014
- Authors: Kibet, Caleb Kipkurui
- Date: 2014
- Subjects: Transcription factors , Chronic myeloid leukemia , Antioncogenes , Cancer cells -- Growth -- Regulation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4115 , http://hdl.handle.net/10962/d1013131
- Description: Transcription factors (TFs) are key regulators of gene expression whose failure has been implicated in many diseases, including cancer. They bind at various sites at different specificity depending on the prevailing cellular conditions, disease, development stage or environmental conditions of the cell. TF binding specificity is how well a TF distinguishes functional sites from potential non-functional sites to form a useful regulatory network. Owing to its role in diseases, various techniques have been used to determine TF binding specificity in vitro and in vivo, including chromatin immuno-precipitation followed by massively parallel sequencing (ChIP-seq). ChIP-seq is an in vivo technique that considers how the chromatin landscape affects TF binding. Motif enrichment analysis (MEA) tools are used to identify motifs that are over-represented in ChIP-seq peak regions. One such tool, CentriMo, finds over-represented motifs at the center since peak calling software are biased to declaring binding regions centered at the TF binding site. In this study, we investigate the use of CentriMo and other MEA tools to determine the difference in motif enrichment attributed presence of Chronic Myeloid leukemia (CML)), treatment with Interferon (IFN) and Dexamethasone (DEX) compared to control based on Fisher’s exact test; using uniform peaks ChIP-seq data generated by the ENCODE consortium. CentriMo proved to be capable. We observed differential motif enrichment of TFs with tumor promoter activity: YY1, CEBPA, Egr1, Cmyc family, Gata1 and JunD in K562 while Stat1, Irf1, and Runx1 in Gm12878. Enrichment of CTCF in Gm12878 with YY1 as the immuno-precipitated (ChIP-ed) factor and the presence of significant spacing (SpaMo analysis) of CTCF and YY1 in Gm12878 but not in K562 could show that CTCF, as a repressor, helps in maintaining the required YY1 level in a normal cell line. IFN might reduce Cmyc and the Jun family of TFs binding via the repressive action of CTCF and E2f2. We also show that the concentration of DEX treatment affects motif enrichment with 50nm being an optimum concentration for Gr binding by maintaining open chromatin via AP1 TF. This study has demonstrated the usefulness of CentriMo for TF binding specificity analysis.
- Full Text:
- Date Issued: 2014
Assessing the genetic diversity of catface rockcod epinephelus andersoni in the subtropical Western Indian Ocean and modelling the effects of climate change on their distribution
- Authors: Coppinger, Christine Rose
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54499 , vital:26570
- Description: The catface rockcod Epinephelus andersoni is a range-restricted species that is endemic to the southeast coast of Africa from Quissico in Mozambique (subtropical) to Knysna in South Africa (warmtemperate). Its complex life-history, long-lived nature and high residency make E. andersoni potentially vulnerable to over-exploitation. Epinephelus andersoni is an important fishery species and has shown signs of depletion. Due to inadequate information necessary for management and conservation, further research is vital, particularly in the face of potentially significant climatic changes which could put further pressure on E. andersoni. The aim of the study was to provide information for the management of E. andersoni, with considerations for the possibly detrimental effects of future climate change. The objectives of this study were to describe the genetic structure and diversity of E. andersoni and to determine possible range shifts of E. andersoni with future changes in sea surface temperature. Genetic samples were collected throughout the distribution of E. andersoni. Standard DNA extraction and PCR using universal primers were conducted and nuclear (RPS7-1) and mitochondrial (cytochrome b) data were analysed to determine genetic diversity. A combination of nuclear and mitochondrial markers was used to ensure that the results were robust. RPS7-1 haplotype diversity was high (0.801) and an AMOVA on the RPS7-1 data showed significantly high among group variation (ΦCT = 0.204, p < 0.05) between five groups: 1. Quissico to Inhaca; 2. Cape Vidal to Port Edward; 3 Port St Johns to Coffee Bay; 4. Mbashe; 5. Port Alfred. This geographic structuring could be attributed to low gene flow across barriers such as the Port Alfred upwelling cell, the Mozambique Channel eddies and smaller more localised upwelling cells such as the Port St Johns cell. The cytochrome b results contrastingly indicate low haplotype diversity (0.309) and no differentiation (ΦCT = 0.265, p = 0.074) between groups and support the hypothesis of a historical population bottleneck. This may be due to an unusually slower mutation rate of the cytochrome b region than the RPS7-1 region, resulting in the RPS7-1 data showing a more recent picture of diversification. To complement the genetic results, niche modelling techniques were used to determine range shifts of E. andersoni with future temperature trends using species distribution and climatic data. The model illustrated a contraction of the E. andersoni distribution as well as future intensification of various upwelling cells along the south-east African coast including the Port Alfred upwelling cell. Due to the low gene flow across these barriers this intensification could decrease the resilience of E. andersoni, as its range becomes more limited with global change. The genetic data and modelling results combined provide useful information on which to base future fisheries management.
- Full Text:
- Date Issued: 2014
- Authors: Coppinger, Christine Rose
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54499 , vital:26570
- Description: The catface rockcod Epinephelus andersoni is a range-restricted species that is endemic to the southeast coast of Africa from Quissico in Mozambique (subtropical) to Knysna in South Africa (warmtemperate). Its complex life-history, long-lived nature and high residency make E. andersoni potentially vulnerable to over-exploitation. Epinephelus andersoni is an important fishery species and has shown signs of depletion. Due to inadequate information necessary for management and conservation, further research is vital, particularly in the face of potentially significant climatic changes which could put further pressure on E. andersoni. The aim of the study was to provide information for the management of E. andersoni, with considerations for the possibly detrimental effects of future climate change. The objectives of this study were to describe the genetic structure and diversity of E. andersoni and to determine possible range shifts of E. andersoni with future changes in sea surface temperature. Genetic samples were collected throughout the distribution of E. andersoni. Standard DNA extraction and PCR using universal primers were conducted and nuclear (RPS7-1) and mitochondrial (cytochrome b) data were analysed to determine genetic diversity. A combination of nuclear and mitochondrial markers was used to ensure that the results were robust. RPS7-1 haplotype diversity was high (0.801) and an AMOVA on the RPS7-1 data showed significantly high among group variation (ΦCT = 0.204, p < 0.05) between five groups: 1. Quissico to Inhaca; 2. Cape Vidal to Port Edward; 3 Port St Johns to Coffee Bay; 4. Mbashe; 5. Port Alfred. This geographic structuring could be attributed to low gene flow across barriers such as the Port Alfred upwelling cell, the Mozambique Channel eddies and smaller more localised upwelling cells such as the Port St Johns cell. The cytochrome b results contrastingly indicate low haplotype diversity (0.309) and no differentiation (ΦCT = 0.265, p = 0.074) between groups and support the hypothesis of a historical population bottleneck. This may be due to an unusually slower mutation rate of the cytochrome b region than the RPS7-1 region, resulting in the RPS7-1 data showing a more recent picture of diversification. To complement the genetic results, niche modelling techniques were used to determine range shifts of E. andersoni with future temperature trends using species distribution and climatic data. The model illustrated a contraction of the E. andersoni distribution as well as future intensification of various upwelling cells along the south-east African coast including the Port Alfred upwelling cell. Due to the low gene flow across these barriers this intensification could decrease the resilience of E. andersoni, as its range becomes more limited with global change. The genetic data and modelling results combined provide useful information on which to base future fisheries management.
- Full Text:
- Date Issued: 2014
Assessment of the Lake Liambezi fishery, Zambezi region, Namibia
- Authors: Simasiku, Evans Kamwi
- Date: 2014
- Subjects: Fishery management -- Namibia -- Lake Liambezi , Seines -- Namibia -- Lake Liambezi , Gillnetting -- Namibia -- Lake Liambezi , Fishes -- Namibia -- Lake Liambezi , Fisheries -- Catch effort -- Namibia -- Lake Liambezi
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5366 , http://hdl.handle.net/10962/d1013036
- Description: Lake Liambezi in the Zambezi Region of Namibia, formerly known as the Caprivi Region, is shallow (<6m deep) and characterised by cyclic episodes of filling and drying. When full the lake supports a highly productive fishery and when dry the lake is completely dry and used for agriculture and grazing. In 2000 the lake filled, and between May 2011 and April 2012 was surveyed using beach seine, experimental gillnets and catch landing surveys to obtain information for conservation and management recommendations for the fishery. Littoral fishes in Lake Liambezi and the Kavango floodplain were sampled using seine net and physicochemical properties were measured. Seine net surveys demonstrated that Lake Liambezi littoral zones were dominated by fishes of the family Alestidae (59.7%) while Cichlids constituted the most diverse family. Juvenile Tilapia rendalli and Oreochromis macrochir were among the five most important species in the littoral zone, indicating that these commercially important species use the littoral zone as a nursery ground. Since T. rendalli and O. macrochir are commercially important species, because of this, it is advised that seine nets should not be used. Catch efficiency between monofilament and multifilament gillnets in Lake Liambezi offshore waters were assessed. Catch efficiency experimental fishing trials showed that monofilament gillnets catch per unit effort (CPUE) was three times higher than that of multifilament gillnets for Oreochromis andersonii, O. macrochir, T. rendalli, Serranochromis macrocephalus and Clarias spp. Oreochromis andersonii comprised over 66% of the overall CPUE for both net types combined indicating the importance of this species in the gillnet fishery on the lake. A fishery has been established on the lake with more than 300 canoes and 120 fishermen using monofilament and multifilament gillnets. CPUE was 15 kg/canoe/day and was significantly (P < 0.05) associated with monthly temperature and moon phase parameters indicating that the fishery of Lake Liambezi may be altered by climate and environmental factors. Annual catch from Lake Liambezi was estimated at 3193t with an estimated productivity of 106kg/ha, suggesting that Lake Liambezi makes a significant contribution to the fish supply in the Zambezi Region. Recommendations were made to manage the Lake Liambezi fishery by imposing restrictions on effort (number of fishing boats), gear type, mesh sizes and access. Proper fisheries management and monitoring should incorporate climatic and environmental factors such as temperature and moon phase to meet the challenges of global climatic changes as well as other environmental issues.
- Full Text:
- Date Issued: 2014
- Authors: Simasiku, Evans Kamwi
- Date: 2014
- Subjects: Fishery management -- Namibia -- Lake Liambezi , Seines -- Namibia -- Lake Liambezi , Gillnetting -- Namibia -- Lake Liambezi , Fishes -- Namibia -- Lake Liambezi , Fisheries -- Catch effort -- Namibia -- Lake Liambezi
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5366 , http://hdl.handle.net/10962/d1013036
- Description: Lake Liambezi in the Zambezi Region of Namibia, formerly known as the Caprivi Region, is shallow (<6m deep) and characterised by cyclic episodes of filling and drying. When full the lake supports a highly productive fishery and when dry the lake is completely dry and used for agriculture and grazing. In 2000 the lake filled, and between May 2011 and April 2012 was surveyed using beach seine, experimental gillnets and catch landing surveys to obtain information for conservation and management recommendations for the fishery. Littoral fishes in Lake Liambezi and the Kavango floodplain were sampled using seine net and physicochemical properties were measured. Seine net surveys demonstrated that Lake Liambezi littoral zones were dominated by fishes of the family Alestidae (59.7%) while Cichlids constituted the most diverse family. Juvenile Tilapia rendalli and Oreochromis macrochir were among the five most important species in the littoral zone, indicating that these commercially important species use the littoral zone as a nursery ground. Since T. rendalli and O. macrochir are commercially important species, because of this, it is advised that seine nets should not be used. Catch efficiency between monofilament and multifilament gillnets in Lake Liambezi offshore waters were assessed. Catch efficiency experimental fishing trials showed that monofilament gillnets catch per unit effort (CPUE) was three times higher than that of multifilament gillnets for Oreochromis andersonii, O. macrochir, T. rendalli, Serranochromis macrocephalus and Clarias spp. Oreochromis andersonii comprised over 66% of the overall CPUE for both net types combined indicating the importance of this species in the gillnet fishery on the lake. A fishery has been established on the lake with more than 300 canoes and 120 fishermen using monofilament and multifilament gillnets. CPUE was 15 kg/canoe/day and was significantly (P < 0.05) associated with monthly temperature and moon phase parameters indicating that the fishery of Lake Liambezi may be altered by climate and environmental factors. Annual catch from Lake Liambezi was estimated at 3193t with an estimated productivity of 106kg/ha, suggesting that Lake Liambezi makes a significant contribution to the fish supply in the Zambezi Region. Recommendations were made to manage the Lake Liambezi fishery by imposing restrictions on effort (number of fishing boats), gear type, mesh sizes and access. Proper fisheries management and monitoring should incorporate climatic and environmental factors such as temperature and moon phase to meet the challenges of global climatic changes as well as other environmental issues.
- Full Text:
- Date Issued: 2014
Bacterial degradation of waste coal
- Authors: Madikiza, Lwazikazi
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54576 , vital:26590
- Description: As an energy source coal has one of the largest agglomerations in the world. Consequently mining of coal creates large volumes of waste in the form of low ranks coals. The complex structure of coal makes it difficult for the microorganisms to degrade and relatively few bacteria and fungi have been shown to break down coal. This study aimed to investigate bacteria not previously known to degrade coal. In this study bacteria were isolated from hydrocarbon contaminated sites and inoculated in coal medium where coal served as the only carbon source. Three strains produced a yellow – brown supernatant after 14 d of incubation at 30 °C. Bacteria generating a yellow – brown coloured supernatant were presumed to possess coal degrading capabilities and the best performing of these bacterial species was identified using 16s rDNA as Bacillus flexus. Scanning electron microscopy showed that there was a close association between the bacterium and substrate coal. The close association of bacteria to substrate suggested that these organisms were able to maximize solubilisation. FT-IR spectroscopic analysis demonstrated the addition of single bonded compounds COOH, OH, CN and CH that were absent prior to bacterial interaction. The increase in oxygen rich regions indicated degradation of the coal substrate. Elemental analysis showed that there was a decrease in carbon content from 47 % to 24 % during the 14 day incubation period. Reduction in coal carbon content was assumed to be due to bacterial utilization for metabolism and growth particularly as untreated coal substrate showed minimal loss of carbon. Analysis of the residual culture medium revealed that there was a linear increase in humic-like substance concentration for 8 d, coincident with increased coal biosolubilisation and colour change. Laccase activity was insignificant, and at 13 d enzyme activity was only 5×10-3 U/L suggesting that B. flexus may use a different mechanism to degrade coal. Residual culture medium remaining after bacterial action on the coal substrate appeared to possess plant growth promoting activity. This soluble biodegradation product with characteristics similar to humic acid-like substances was shown to impact growth of radish cotyledons. Expansion of isolated radish cotyledons was enhanced by 140% when incubated in coal biodegradation product. In conclusion, this study has yielded B. flexus and two other unidentified bacteria, isolated from polyaromatic hydrocarbon contaminated soils, and demonstrated the ability of these microorganisms to degrade waste coal. Further studies to elucidate the mechanism of coal breakdown by B. flexus, synergies with other coal degrading microorganisms, and incorporation of bacterium into Fungcoal bioprocess technology is imminent.
- Full Text:
- Date Issued: 2014
- Authors: Madikiza, Lwazikazi
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54576 , vital:26590
- Description: As an energy source coal has one of the largest agglomerations in the world. Consequently mining of coal creates large volumes of waste in the form of low ranks coals. The complex structure of coal makes it difficult for the microorganisms to degrade and relatively few bacteria and fungi have been shown to break down coal. This study aimed to investigate bacteria not previously known to degrade coal. In this study bacteria were isolated from hydrocarbon contaminated sites and inoculated in coal medium where coal served as the only carbon source. Three strains produced a yellow – brown supernatant after 14 d of incubation at 30 °C. Bacteria generating a yellow – brown coloured supernatant were presumed to possess coal degrading capabilities and the best performing of these bacterial species was identified using 16s rDNA as Bacillus flexus. Scanning electron microscopy showed that there was a close association between the bacterium and substrate coal. The close association of bacteria to substrate suggested that these organisms were able to maximize solubilisation. FT-IR spectroscopic analysis demonstrated the addition of single bonded compounds COOH, OH, CN and CH that were absent prior to bacterial interaction. The increase in oxygen rich regions indicated degradation of the coal substrate. Elemental analysis showed that there was a decrease in carbon content from 47 % to 24 % during the 14 day incubation period. Reduction in coal carbon content was assumed to be due to bacterial utilization for metabolism and growth particularly as untreated coal substrate showed minimal loss of carbon. Analysis of the residual culture medium revealed that there was a linear increase in humic-like substance concentration for 8 d, coincident with increased coal biosolubilisation and colour change. Laccase activity was insignificant, and at 13 d enzyme activity was only 5×10-3 U/L suggesting that B. flexus may use a different mechanism to degrade coal. Residual culture medium remaining after bacterial action on the coal substrate appeared to possess plant growth promoting activity. This soluble biodegradation product with characteristics similar to humic acid-like substances was shown to impact growth of radish cotyledons. Expansion of isolated radish cotyledons was enhanced by 140% when incubated in coal biodegradation product. In conclusion, this study has yielded B. flexus and two other unidentified bacteria, isolated from polyaromatic hydrocarbon contaminated soils, and demonstrated the ability of these microorganisms to degrade waste coal. Further studies to elucidate the mechanism of coal breakdown by B. flexus, synergies with other coal degrading microorganisms, and incorporation of bacterium into Fungcoal bioprocess technology is imminent.
- Full Text:
- Date Issued: 2014
Biological control as an integrated control method in the management of aquatic weeds in an urban environmental and socio-political landscape : case study : Cape Town Metropolitan Area
- Authors: Stafford, Martha Louise
- Date: 2014
- Subjects: Aquatic weeds -- South Africa -- Cape Town , Aquatic weeds -- Biological control -- South Africa -- Cape Town , Water hyacinth -- Biological control -- South Africa -- Cape Town , Metropolitan areas -- South Africa -- Cape Town
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5874 , http://hdl.handle.net/10962/d1013015
- Description: Aquatic weeds transform and degrade the ecosystems which they invade, impacting various aspects of their surroundings ranging from the community level to disrupting important processes affecting ecosystem services. All of the major aquatic weeds of South Africa are found in the Cape Town Metropolitan Area. Landowners, whether private or public, are legally obliged to manage the listed invasive species through applying environmentally acceptable methodologies. This thesis provides an overview of the strategic management options, prevention, early detection, rapid response and eradication of new invasions, and containment and control species of established species. It discusses the different control methods available for managing aquatic weeds, namely mechanical, manual, chemical and biological, and the integration of different methods to improve their effectiveness. Although various studies have shown that biological control is the most cost–effective, environmentally-friendly and sustainable method, it is not yet fully integrated into weed management programmes in South Africa. In addition, the successes achieved in other parts of the world with the control of water hyacinth through biological control have not been repeated in the urban environment, despite the fact that South Africa has the highest number of biological control agents available for the weed. Urbanisation puts pressure on the natural environment and ecosystem functioning. Nutrient-enriched waters support aquatic weed growth and pose a challenge to the management thereof, in particular with regard to integrating biological control into management programmes. The aims of this study were to determine the reasons for the lack of integration of biological control into weed management programmes in South Africa, to determine the feasibility of integrating biological control in aquatic weed management programmes in a complex urban environmental and socio-political landscape by means of three case studies in the Cape Town Metropolitan Area, which showed that biological control is feasible in urban environments and should be considered. Two surveys were conducted to determine the reasons for the lack of integration of biological control into weed management programmes. The surveys showed that there is a gap between research and implementation as a result of poor communication, non-supporting institutional arrangements and a lack of appropriate capacity and skills at the implementation level. Recommendations were offered to address these issues.
- Full Text:
- Date Issued: 2014
- Authors: Stafford, Martha Louise
- Date: 2014
- Subjects: Aquatic weeds -- South Africa -- Cape Town , Aquatic weeds -- Biological control -- South Africa -- Cape Town , Water hyacinth -- Biological control -- South Africa -- Cape Town , Metropolitan areas -- South Africa -- Cape Town
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5874 , http://hdl.handle.net/10962/d1013015
- Description: Aquatic weeds transform and degrade the ecosystems which they invade, impacting various aspects of their surroundings ranging from the community level to disrupting important processes affecting ecosystem services. All of the major aquatic weeds of South Africa are found in the Cape Town Metropolitan Area. Landowners, whether private or public, are legally obliged to manage the listed invasive species through applying environmentally acceptable methodologies. This thesis provides an overview of the strategic management options, prevention, early detection, rapid response and eradication of new invasions, and containment and control species of established species. It discusses the different control methods available for managing aquatic weeds, namely mechanical, manual, chemical and biological, and the integration of different methods to improve their effectiveness. Although various studies have shown that biological control is the most cost–effective, environmentally-friendly and sustainable method, it is not yet fully integrated into weed management programmes in South Africa. In addition, the successes achieved in other parts of the world with the control of water hyacinth through biological control have not been repeated in the urban environment, despite the fact that South Africa has the highest number of biological control agents available for the weed. Urbanisation puts pressure on the natural environment and ecosystem functioning. Nutrient-enriched waters support aquatic weed growth and pose a challenge to the management thereof, in particular with regard to integrating biological control into management programmes. The aims of this study were to determine the reasons for the lack of integration of biological control into weed management programmes in South Africa, to determine the feasibility of integrating biological control in aquatic weed management programmes in a complex urban environmental and socio-political landscape by means of three case studies in the Cape Town Metropolitan Area, which showed that biological control is feasible in urban environments and should be considered. Two surveys were conducted to determine the reasons for the lack of integration of biological control into weed management programmes. The surveys showed that there is a gap between research and implementation as a result of poor communication, non-supporting institutional arrangements and a lack of appropriate capacity and skills at the implementation level. Recommendations were offered to address these issues.
- Full Text:
- Date Issued: 2014
Biospeciation and antidiabetic effects of oxidovanadium(IV) complexes
- Authors: Ugirinema, Vital
- Date: 2014
- Subjects: Vanadium compounds , Diabetes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10442 , http://hdl.handle.net/10948/d1020973
- Description: The syntheses of bis(1R-imidazole-2/4-carboxylato)oxidovanadium(IV) complexes was successfully carried out and the complexes were isolated in the solid state. The coordinated water was confirmed by elemental analyses, and single crystal XRD. The complexes were therefore distorted octahedral rather than square planar due to the coordination of water at the sixth position. The reaction of the vanadyl ion (VO2+) with imidazole-4-carboxylic acid (Im4COOH), imidazole-2-carboxylic acid (Im2COOH) and methylimidazole-2-carboxylic acid (MeIm2COOH), respectively, in the presence of small bioligands (bL) [oxalate (Ox), lactate (Lact), and phosphate (Phos)] and high molecular weight (HMM) human serum proteins [albumin (HSA) and transferrin (hTf)] were studied in aqueous solution using potentiometric acid base titrations under oxygen and carbon dioxide–free conditions. The data obtained from these titrations was used to calculate the binary and ternary stability constants using the programme HYPERQUAD. The overall stability constants for VO2+-L-Ox system (log β1111 = 18.9, 18.79 and 19.86), VO2+-L-Lact system (log β1111 = 21.83, 20.98 and 22.86), and VO2+-L-Phos system (log β1111 = 27.35, 24.16 and 27.42) (for L= Im4COOH, Im2COOH and MeIm2COOH, respectively) were obtained. The species distribution diagrams showed that under physiological pH the following ternary and quaternary species; [(VO)L(bL)], and [VO(L)(bL)(OH)], would dominate provided that the competition with serum proteins is not too strong. These species were also confirmed by HPLC, LC-MS and EPR. The overall stability constants for the VO2+-L-HSA system (log β2,1,1,0 = 24.3, 23.7 and 24.7), and for the VO2+-L-hTf system (log β2,2,1,0 = 31.1, 30.8, 36.4 for L = Im4COOH, Im2COOH and MeIm2COOH, respectively), suggesting stronger binding of transferrin. The formation constants for the formation of binary (VO(IV) and the proteins) were 9.1 and 13 for log β11, and 20.9 and 25.2 for β12, for human serum albumin and human serum transferrin respectively. The species distribution diagrams for the proteins (HMM) with oxidovanadium(IV) under physiological pH was dominated by VO(HMM)2, VOL(HMM) for unsubstituted Im4COOH and Im2COOH, however, for the N-substituted MeIm2COOH, the species distribution diagrams under physiological pH, were dominated by VOL2, VO(HMM)2 and VO2L2(HMM). These species were further confirmed by HPLC, MALDI-TOF-MS and EPR. The glucose stimulated insulin secretion (GSIS) action of the complexes was investigated using INS-1E cells at 1μM concentration which was established through cytotoxicity studies via the MTT assay. The vanadium salt (VOSO4), cationic vanadium(IV) complex ([VO(MeImCH2OH)2]2+) were also included in the GSIS study in addition to the three neutral complexes [VO(Im4COO)2, VO(Im2COO)2 and VO(MeIm2COO)2] for comparison. The neutral complexes, especially VO(MeIm2COO)2, showed promising results in the stimulation of insulin secretion than the cationic complex and the vanadium salt.
- Full Text:
- Date Issued: 2014
- Authors: Ugirinema, Vital
- Date: 2014
- Subjects: Vanadium compounds , Diabetes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10442 , http://hdl.handle.net/10948/d1020973
- Description: The syntheses of bis(1R-imidazole-2/4-carboxylato)oxidovanadium(IV) complexes was successfully carried out and the complexes were isolated in the solid state. The coordinated water was confirmed by elemental analyses, and single crystal XRD. The complexes were therefore distorted octahedral rather than square planar due to the coordination of water at the sixth position. The reaction of the vanadyl ion (VO2+) with imidazole-4-carboxylic acid (Im4COOH), imidazole-2-carboxylic acid (Im2COOH) and methylimidazole-2-carboxylic acid (MeIm2COOH), respectively, in the presence of small bioligands (bL) [oxalate (Ox), lactate (Lact), and phosphate (Phos)] and high molecular weight (HMM) human serum proteins [albumin (HSA) and transferrin (hTf)] were studied in aqueous solution using potentiometric acid base titrations under oxygen and carbon dioxide–free conditions. The data obtained from these titrations was used to calculate the binary and ternary stability constants using the programme HYPERQUAD. The overall stability constants for VO2+-L-Ox system (log β1111 = 18.9, 18.79 and 19.86), VO2+-L-Lact system (log β1111 = 21.83, 20.98 and 22.86), and VO2+-L-Phos system (log β1111 = 27.35, 24.16 and 27.42) (for L= Im4COOH, Im2COOH and MeIm2COOH, respectively) were obtained. The species distribution diagrams showed that under physiological pH the following ternary and quaternary species; [(VO)L(bL)], and [VO(L)(bL)(OH)], would dominate provided that the competition with serum proteins is not too strong. These species were also confirmed by HPLC, LC-MS and EPR. The overall stability constants for the VO2+-L-HSA system (log β2,1,1,0 = 24.3, 23.7 and 24.7), and for the VO2+-L-hTf system (log β2,2,1,0 = 31.1, 30.8, 36.4 for L = Im4COOH, Im2COOH and MeIm2COOH, respectively), suggesting stronger binding of transferrin. The formation constants for the formation of binary (VO(IV) and the proteins) were 9.1 and 13 for log β11, and 20.9 and 25.2 for β12, for human serum albumin and human serum transferrin respectively. The species distribution diagrams for the proteins (HMM) with oxidovanadium(IV) under physiological pH was dominated by VO(HMM)2, VOL(HMM) for unsubstituted Im4COOH and Im2COOH, however, for the N-substituted MeIm2COOH, the species distribution diagrams under physiological pH, were dominated by VOL2, VO(HMM)2 and VO2L2(HMM). These species were further confirmed by HPLC, MALDI-TOF-MS and EPR. The glucose stimulated insulin secretion (GSIS) action of the complexes was investigated using INS-1E cells at 1μM concentration which was established through cytotoxicity studies via the MTT assay. The vanadium salt (VOSO4), cationic vanadium(IV) complex ([VO(MeImCH2OH)2]2+) were also included in the GSIS study in addition to the three neutral complexes [VO(Im4COO)2, VO(Im2COO)2 and VO(MeIm2COO)2] for comparison. The neutral complexes, especially VO(MeIm2COO)2, showed promising results in the stimulation of insulin secretion than the cationic complex and the vanadium salt.
- Full Text:
- Date Issued: 2014
Cardiovascular disease risk in Black African females and the efficacy of a walking programme on blood pressure in a sub-sample
- Authors: Crymble, Tegan
- Date: 2014
- Subjects: Cardiovascular system -- Diseases -- South Africa -- Eastern Cape , Women -- Health and hygiene -- South Africa -- Eastern Cape , Obesity -- South Africa -- Eastern Cape , Hypertension -- South Africa -- Eastern Cape , Walking -- South Africa -- Eastern Cape -- Physiological aspects , Lifestyles -- Health aspects -- South Africa -- Eastern Cape , Health attitudes -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5152 , http://hdl.handle.net/10962/d1013234
- Description: The purpose of the study was to investigate the cardiovascular disease (CVD) risk profile of black African females in the Makana region, Eastern Cape, South Africa. Baseline measures from 40 participants, who met the criteria, were compared against the 2003 South African Demographic and Health Survey (SADHS) and the 2013 South African National Health and Nutritional Examination Survey (SANHANES-1). The risk factors measured were anthropometric (stature, body mass and body mass index (BMI)), morphological (waist circumference (WC), fat mass and lean mass), cardiovascular (heart rate and blood pressure (BP)), physical activity (step count and energy expenditure), biochemical (glycated haemoglobin and full blood lipid profile) and behavioural (alcohol and tobacco use). Results showed significantly higher (p≤0.05) values for overweight/obesity (BMI 37.60 kg.m⁻²; WC 1130.58 mm; fat mass 45.23%) and high BP (130/88 mmHg) compared to the previous national surveys, highlighting these CVD risk factors as problematic. The subsequent sub-study aimed to assess the efficacy of a pedometer-based walking intervention on high BP. The walking programme (n=25) was based on individual step goals to be completed at a moderate-intensity on five days.week⁻¹ for 12 weeks. The same measurements were taken at monthly intervals, Week 0, Week 4, Week 8 and Week 12, with the addition of dietary intake and fitness level, and the exclusion of the behavioural variables. There were no significant differences (p≤0.05) in systolic and diastolic BP with the exercise intervention, although there was a strong, negative relationship with time for diastolic BP (r²=0.9857). This trend suggests that the lack of significance may be a result of poor compliance and/or the small sample size. Individual results, however, showed no compliance-result relationship for the two risk factors of interest: overweight/obesity and high BP. Future recommendations include supervised or group-based exercise interventions to improve compliance, and the addition of resistance training to the aerobic programme.
- Full Text:
- Date Issued: 2014
- Authors: Crymble, Tegan
- Date: 2014
- Subjects: Cardiovascular system -- Diseases -- South Africa -- Eastern Cape , Women -- Health and hygiene -- South Africa -- Eastern Cape , Obesity -- South Africa -- Eastern Cape , Hypertension -- South Africa -- Eastern Cape , Walking -- South Africa -- Eastern Cape -- Physiological aspects , Lifestyles -- Health aspects -- South Africa -- Eastern Cape , Health attitudes -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5152 , http://hdl.handle.net/10962/d1013234
- Description: The purpose of the study was to investigate the cardiovascular disease (CVD) risk profile of black African females in the Makana region, Eastern Cape, South Africa. Baseline measures from 40 participants, who met the criteria, were compared against the 2003 South African Demographic and Health Survey (SADHS) and the 2013 South African National Health and Nutritional Examination Survey (SANHANES-1). The risk factors measured were anthropometric (stature, body mass and body mass index (BMI)), morphological (waist circumference (WC), fat mass and lean mass), cardiovascular (heart rate and blood pressure (BP)), physical activity (step count and energy expenditure), biochemical (glycated haemoglobin and full blood lipid profile) and behavioural (alcohol and tobacco use). Results showed significantly higher (p≤0.05) values for overweight/obesity (BMI 37.60 kg.m⁻²; WC 1130.58 mm; fat mass 45.23%) and high BP (130/88 mmHg) compared to the previous national surveys, highlighting these CVD risk factors as problematic. The subsequent sub-study aimed to assess the efficacy of a pedometer-based walking intervention on high BP. The walking programme (n=25) was based on individual step goals to be completed at a moderate-intensity on five days.week⁻¹ for 12 weeks. The same measurements were taken at monthly intervals, Week 0, Week 4, Week 8 and Week 12, with the addition of dietary intake and fitness level, and the exclusion of the behavioural variables. There were no significant differences (p≤0.05) in systolic and diastolic BP with the exercise intervention, although there was a strong, negative relationship with time for diastolic BP (r²=0.9857). This trend suggests that the lack of significance may be a result of poor compliance and/or the small sample size. Individual results, however, showed no compliance-result relationship for the two risk factors of interest: overweight/obesity and high BP. Future recommendations include supervised or group-based exercise interventions to improve compliance, and the addition of resistance training to the aerobic programme.
- Full Text:
- Date Issued: 2014
Causes and effects of non-payment of residential property rates in Mahikeng
- Authors: Asianoah, Rexford Kofi
- Date: 2014
- Subjects: Debts, Public -- South Africa -- Mahikeng , Municipal default -- South Africa -- Mahikeng , Public utilities -- South Africa -- Mahikeng , Collecting of accounts -- South Africa -- Mahikeng
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9674 , http://hdl.handle.net/10948/d1020076
- Description: One of the major sources of income to South African Municipalities is property rates. Income generated from property rates is meant to develop and deliver services to residents living in the said Municipal area. The main aim of the research was to identify the causes and effects of the non-payment of residential property rates, and also to develop workable strategies to maximise the collection of residential property rates in order to ensure developmental growth sustenance, specifically in Mahikeng Municipal area. Related literature was reviewed on the non-financial viability of Municipalities, maintenance of public infrastructure, service delivery and Municipal development plans in establishing the relationship with non-payment of residential property rates. Four hypotheses were set to guide the research with two testing positive with high level of confidence using the chi square method of testing. The research methodology employed in the research was mainly quantitative where the results and findings obtained from the questionnaire were statistically analysed. The research revealed that: The Mahikeng Local Municipality has failed to find the right medium to send rates bills to clients on time, is not taking active responsibility to recover rates debts, does not provide quality service delivery and the reluctance by locals to pay their property rates. The effects thereof, are the inability of the Municipality to deliver effective and efficient services, lack of maintenance of public infrastructure and development in the area. By implementing various options such as email, sms and the post to send rates bills to property owners, by employing different payment options, for example debit orders, transfers, bank deposits and discounts for property owners and embarking on periodic public awareness campaigns in educating the community regarding the importance of payment of property rates could serve as effective mechanisms to address the non-payment of residential property rates faced by the Mahikeng Local Municipality.
- Full Text:
- Date Issued: 2014
- Authors: Asianoah, Rexford Kofi
- Date: 2014
- Subjects: Debts, Public -- South Africa -- Mahikeng , Municipal default -- South Africa -- Mahikeng , Public utilities -- South Africa -- Mahikeng , Collecting of accounts -- South Africa -- Mahikeng
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9674 , http://hdl.handle.net/10948/d1020076
- Description: One of the major sources of income to South African Municipalities is property rates. Income generated from property rates is meant to develop and deliver services to residents living in the said Municipal area. The main aim of the research was to identify the causes and effects of the non-payment of residential property rates, and also to develop workable strategies to maximise the collection of residential property rates in order to ensure developmental growth sustenance, specifically in Mahikeng Municipal area. Related literature was reviewed on the non-financial viability of Municipalities, maintenance of public infrastructure, service delivery and Municipal development plans in establishing the relationship with non-payment of residential property rates. Four hypotheses were set to guide the research with two testing positive with high level of confidence using the chi square method of testing. The research methodology employed in the research was mainly quantitative where the results and findings obtained from the questionnaire were statistically analysed. The research revealed that: The Mahikeng Local Municipality has failed to find the right medium to send rates bills to clients on time, is not taking active responsibility to recover rates debts, does not provide quality service delivery and the reluctance by locals to pay their property rates. The effects thereof, are the inability of the Municipality to deliver effective and efficient services, lack of maintenance of public infrastructure and development in the area. By implementing various options such as email, sms and the post to send rates bills to property owners, by employing different payment options, for example debit orders, transfers, bank deposits and discounts for property owners and embarking on periodic public awareness campaigns in educating the community regarding the importance of payment of property rates could serve as effective mechanisms to address the non-payment of residential property rates faced by the Mahikeng Local Municipality.
- Full Text:
- Date Issued: 2014
Characterization and application of phthalocyanine-magnetic nanoparticle conjugates anchored to electrospun polyamide nanofibers
- Authors: Ledwaba, Mpho
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54610 , vital:26593
- Description: This work presents the syntheses, photophysical and photochemical characterization of zinc tetracarboxyphenoxy phthalocyanine (ZnTCPPc, 3) and its gadolinium oxide nanoparticle conjugate (4). By means of spectroscopic and microscopic characterization, the conjugation of the ZnTCPPc to the silica coated gadolinium oxide nanoparticles (Si-Gd2O3 NPs, 2) through an amide bond was confirmed. The thermal stability, morphology, nanoparticle sizes and their conjugates with the Pc were studied using ThermoGravimetric Analysis (TGA), Fourier Transform Infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and powder X-ray diffractometry (XRD). Conjugation of ZnTCPPc to the magnetic nanoparticles, proved to have a negligible effect on the photophysical parameters of the phthalocyanine, where a slight decrease in fluorescence and triplet quantum yields and lifetimes was observed. The singlet oxygen quantum yield, however, increased slightly upon conjugation, suggesting that the overall efficiency of the ZnTCPPc as a photosensitizer had improved. Physical mixing of the ZnTCPPc and the silica-coated gadolinium nanoparticles also showed an improvement in the singlet oxygen quantum yield and triplet lifetime, also showing an enhanced efficiency for the photosensitizer and therefore photocatalysis. ZnTCPPc (3) alone and the Pc-gadolinium oxide nanoparticle conjugate (4) were therefore electrospun into nanofibers to create a solid support. The fibers were characterized and their diameter sizes and composition was studied confirming the incorporation of the phthalocyanine and gadolinium oxide nanoparticle. Increased singlet oxygen generation resulted in increased Photodegradation of the environmental pollutant Orange G and the fibers were found to be more efficient as photocatalysts compared to the photosensitizer in solution. The nanomaterial may therefore be applied to the photodegradation of Orange G.
- Full Text:
- Date Issued: 2014
- Authors: Ledwaba, Mpho
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54610 , vital:26593
- Description: This work presents the syntheses, photophysical and photochemical characterization of zinc tetracarboxyphenoxy phthalocyanine (ZnTCPPc, 3) and its gadolinium oxide nanoparticle conjugate (4). By means of spectroscopic and microscopic characterization, the conjugation of the ZnTCPPc to the silica coated gadolinium oxide nanoparticles (Si-Gd2O3 NPs, 2) through an amide bond was confirmed. The thermal stability, morphology, nanoparticle sizes and their conjugates with the Pc were studied using ThermoGravimetric Analysis (TGA), Fourier Transform Infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and powder X-ray diffractometry (XRD). Conjugation of ZnTCPPc to the magnetic nanoparticles, proved to have a negligible effect on the photophysical parameters of the phthalocyanine, where a slight decrease in fluorescence and triplet quantum yields and lifetimes was observed. The singlet oxygen quantum yield, however, increased slightly upon conjugation, suggesting that the overall efficiency of the ZnTCPPc as a photosensitizer had improved. Physical mixing of the ZnTCPPc and the silica-coated gadolinium nanoparticles also showed an improvement in the singlet oxygen quantum yield and triplet lifetime, also showing an enhanced efficiency for the photosensitizer and therefore photocatalysis. ZnTCPPc (3) alone and the Pc-gadolinium oxide nanoparticle conjugate (4) were therefore electrospun into nanofibers to create a solid support. The fibers were characterized and their diameter sizes and composition was studied confirming the incorporation of the phthalocyanine and gadolinium oxide nanoparticle. Increased singlet oxygen generation resulted in increased Photodegradation of the environmental pollutant Orange G and the fibers were found to be more efficient as photocatalysts compared to the photosensitizer in solution. The nanomaterial may therefore be applied to the photodegradation of Orange G.
- Full Text:
- Date Issued: 2014
Characterization of animal fibres
- Authors: Notayi, Mzwamadoda
- Date: 2014
- Subjects: Animal fibres , Textile fabrics , Animal science
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10552 , http://hdl.handle.net/10948/d1020426
- Description: Identification of fibres, particularly in blends, requires knowledge of their characteristics. Individual Identifying features between wool and mohair fibres were investigated in this study using a Scanning Electron Microscope (SEM), Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR), Fourier Transform Raman and Atomic Force Microscope (AFM). This study confirmed that wool and mohair can be differentiated and identified in blends using the cuticle scale height (CSH) criterion, wool having an average CSH of 0.6 ± 0.1 μm and mohair having an average CSH of 0.4 ± 0.1 μm. The AFM provided highly reproducible CSH results, which also confirmed the SEM results that indeed wool and mohair could be differentiated using the CSH as criterion. The AFM gave a CSH value of 0.9 ± 0.2 μm for wool and 0.6 ± 0.2 μm for mohair, the difference between the two results being statistically significant according to the student t-test. It has been demonstrated that wool and mohair identification in blends is possible, by using the AFM to measure CSH, although the method is very time consuming and might be expensive. The FTIR-ATR showed similar spectra for wool and mohair fibres, confirming that the two fibre types consist of the same polymer material. Nevertheless, a difference was observed in the ratios of the relative intensities of the amide I (around 1630 cm-1) to the amide II (around 1515cm-1) absorption bands. The FT Raman provided similar spectra for the wool and mohair fibres, although a possible distinguishing feature between the two fibres could be the intensities of the alkyl side chains chemical band near 2940 cm-1 in the spectra of the two fibre types. According to the results obtained in this study, the FTIR-ATR and the FT Raman techniques may have potential for differentiating between wool and mohair but this requires further investigation.
- Full Text:
- Date Issued: 2014
- Authors: Notayi, Mzwamadoda
- Date: 2014
- Subjects: Animal fibres , Textile fabrics , Animal science
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10552 , http://hdl.handle.net/10948/d1020426
- Description: Identification of fibres, particularly in blends, requires knowledge of their characteristics. Individual Identifying features between wool and mohair fibres were investigated in this study using a Scanning Electron Microscope (SEM), Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR), Fourier Transform Raman and Atomic Force Microscope (AFM). This study confirmed that wool and mohair can be differentiated and identified in blends using the cuticle scale height (CSH) criterion, wool having an average CSH of 0.6 ± 0.1 μm and mohair having an average CSH of 0.4 ± 0.1 μm. The AFM provided highly reproducible CSH results, which also confirmed the SEM results that indeed wool and mohair could be differentiated using the CSH as criterion. The AFM gave a CSH value of 0.9 ± 0.2 μm for wool and 0.6 ± 0.2 μm for mohair, the difference between the two results being statistically significant according to the student t-test. It has been demonstrated that wool and mohair identification in blends is possible, by using the AFM to measure CSH, although the method is very time consuming and might be expensive. The FTIR-ATR showed similar spectra for wool and mohair fibres, confirming that the two fibre types consist of the same polymer material. Nevertheless, a difference was observed in the ratios of the relative intensities of the amide I (around 1630 cm-1) to the amide II (around 1515cm-1) absorption bands. The FT Raman provided similar spectra for the wool and mohair fibres, although a possible distinguishing feature between the two fibres could be the intensities of the alkyl side chains chemical band near 2940 cm-1 in the spectra of the two fibre types. According to the results obtained in this study, the FTIR-ATR and the FT Raman techniques may have potential for differentiating between wool and mohair but this requires further investigation.
- Full Text:
- Date Issued: 2014