Life-history characteristics of an age-validated established invasive African sharptooth catfish, Clarias gariepinus, population in a warm-temperate African impoundment
- Wartenberg, Reece, Weyl, Olaf L F, Booth, Anthony J, Winker, A Henning
- Authors: Wartenberg, Reece , Weyl, Olaf L F , Booth, Anthony J , Winker, A Henning
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443542 , vital:74130 , https://hdl.handle.net/10520/EJC145790
- Description: It has been suggested that the invasive, omnivorous Clarias garipienus is capable of rapid invasions and long-term persistence in recently inhabited freshwater systems. To test this hypothesis, the life history of the established, extralimital Darlington Dam (33°10'31"S, 25°09'13"E) population was investigated. By counting post-fluorescent mark increments on otoliths from 21 chemically tagged wild fish recaptured 244-537 days later, the deposition of growth zones, comprising alternating opaque and translucent bands, was validated as annual. Examination of sectioned otoliths from 175 fish revealed that the oldest fish, two males of 840 and 1074 mm total length (TL), were 25 years old - 10 years older than previously described for any C. gariepinus population. The oldest female was 885 mm TL and 21 years old. Length-at-age was subsequently described using the von Bertalanffy growth model. Combined-sex growth was best described as Lt = 931.7 ( 1 - exp(-0.15(t +2.43))) mm TL. Total mortality (Z) was calculated using catch curve analysis and the Chapman and Robson estimator to be 0.35/yr. The presence of specimens 15 years and older indicates that these fish established quickly and supports the finding that mortality rates are low, which, in turn, suggests likely long-term population persistence.
- Full Text:
- Date Issued: 2014
- Authors: Wartenberg, Reece , Weyl, Olaf L F , Booth, Anthony J , Winker, A Henning
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443542 , vital:74130 , https://hdl.handle.net/10520/EJC145790
- Description: It has been suggested that the invasive, omnivorous Clarias garipienus is capable of rapid invasions and long-term persistence in recently inhabited freshwater systems. To test this hypothesis, the life history of the established, extralimital Darlington Dam (33°10'31"S, 25°09'13"E) population was investigated. By counting post-fluorescent mark increments on otoliths from 21 chemically tagged wild fish recaptured 244-537 days later, the deposition of growth zones, comprising alternating opaque and translucent bands, was validated as annual. Examination of sectioned otoliths from 175 fish revealed that the oldest fish, two males of 840 and 1074 mm total length (TL), were 25 years old - 10 years older than previously described for any C. gariepinus population. The oldest female was 885 mm TL and 21 years old. Length-at-age was subsequently described using the von Bertalanffy growth model. Combined-sex growth was best described as Lt = 931.7 ( 1 - exp(-0.15(t +2.43))) mm TL. Total mortality (Z) was calculated using catch curve analysis and the Chapman and Robson estimator to be 0.35/yr. The presence of specimens 15 years and older indicates that these fish established quickly and supports the finding that mortality rates are low, which, in turn, suggests likely long-term population persistence.
- Full Text:
- Date Issued: 2014
A baseline study of potentially malicious activity across five network telescopes
- Authors: Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429714 , vital:72634 , https://ieeexplore.ieee.org/abstract/document/6568378
- Description: +This paper explores the Internet Background Radiation (IBR) observed across five distinct network telescopes over a 15 month period. These network telescopes consisting of a /24 netblock each and are deployed in IP space administered by TENET, the tertiary education network in South Africa covering three numerically distant /8 network blocks. The differences and similarities in the observed network traffic are explored. Two anecdotal case studies are presented relating to the MS08-067 and MS12-020 vulnerabilities in the Microsoft Windows platforms. The first of these is related to the Conficker worm outbreak in 2008, and traffic targeting 445/tcp remains one of the top constituents of IBR as observed on the telescopes. The case of MS12-020 is of interest, as a long period of scanning activity targeting 3389/tcp, used by the Microsoft RDP service, was observed, with a significant drop on activity relating to the release of the security advisory and patch. Other areas of interest are highlighted, particularly where correlation in scanning activity was observed across the sensors. The paper concludes with some discussion on the application of network telescopes as part of a cyber-defence solution.
- Full Text:
- Date Issued: 2013
- Authors: Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429714 , vital:72634 , https://ieeexplore.ieee.org/abstract/document/6568378
- Description: +This paper explores the Internet Background Radiation (IBR) observed across five distinct network telescopes over a 15 month period. These network telescopes consisting of a /24 netblock each and are deployed in IP space administered by TENET, the tertiary education network in South Africa covering three numerically distant /8 network blocks. The differences and similarities in the observed network traffic are explored. Two anecdotal case studies are presented relating to the MS08-067 and MS12-020 vulnerabilities in the Microsoft Windows platforms. The first of these is related to the Conficker worm outbreak in 2008, and traffic targeting 445/tcp remains one of the top constituents of IBR as observed on the telescopes. The case of MS12-020 is of interest, as a long period of scanning activity targeting 3389/tcp, used by the Microsoft RDP service, was observed, with a significant drop on activity relating to the release of the security advisory and patch. Other areas of interest are highlighted, particularly where correlation in scanning activity was observed across the sensors. The paper concludes with some discussion on the application of network telescopes as part of a cyber-defence solution.
- Full Text:
- Date Issued: 2013
Audio Device Representation, Control, and Monitoring Using SNMP
- Eales, Andrew, Foss, Richard
- Authors: Eales, Andrew , Foss, Richard
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426855 , vital:72396 , https://www.aes.org/e-lib/browse.cfm?elib=17012
- Description: The Simple Network Management Protocol (SNMP) is widely used to configure and monitor networked devices. The architecture of complex audio devices can be elegantly represented using SNMP tables. Carefully considered table indexing schemes support a logical device model that can be accessed using standard SNMP commands. This paper examines the use of SNMP tables to represent the architecture of audio devices. A representational scheme that uses table indexes to provide direct-access to context-sensitive SNMP data objects is presented. The monitoring of parameter values and the implementation of connection management using SNMP are also discussed.
- Full Text:
- Date Issued: 2013
- Authors: Eales, Andrew , Foss, Richard
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426855 , vital:72396 , https://www.aes.org/e-lib/browse.cfm?elib=17012
- Description: The Simple Network Management Protocol (SNMP) is widely used to configure and monitor networked devices. The architecture of complex audio devices can be elegantly represented using SNMP tables. Carefully considered table indexing schemes support a logical device model that can be accessed using standard SNMP commands. This paper examines the use of SNMP tables to represent the architecture of audio devices. A representational scheme that uses table indexes to provide direct-access to context-sensitive SNMP data objects is presented. The monitoring of parameter values and the implementation of connection management using SNMP are also discussed.
- Full Text:
- Date Issued: 2013
Developing a virtualised testbed environment in preparation for testing of network based attacks
- Van Heerden, Renier, Pieterse, Heloise, Burke, Ivan, Irwin, Barry V W
- Authors: Van Heerden, Renier , Pieterse, Heloise , Burke, Ivan , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429648 , vital:72629 , 10.1109/ICASTech.2013.6707509
- Description: Computer network attacks are difficult to simulate due to the damage they may cause to live networks and the complexity required simulating a useful network. We constructed a virtualised network within a vSphereESXi environment which is able to simulate: thirty workstations, ten servers, three distinct network segments and the accompanying network traffic. The VSphere environment provided added benefits, such as the ability to pause, restart and snapshot virtual computers. These abilities enabled the authors to reset the simulation environment before each test and mitigated against the damage that an attack potentially inflicts on the test network. Without simulated network traffic, the virtualised network was too sterile. This resulted in any network event being a simple task to detect, making network traffic simulation a requirement for an event detection test bed. Five main kinds of traffic were simulated: Web browsing, File transfer, e-mail, version control and Intranet File traffic. The simulated traffic volumes were pseudo randomised to represent differing temporal patterns. By building a virtualised network with simulated traffic we were able to test IDS' and other network attack detection sensors in a much more realistic environment before moving it to a live network. The goal of this paper is to present a virtualised testbedenvironmentin which network attacks can safely be tested.
- Full Text:
- Date Issued: 2013
- Authors: Van Heerden, Renier , Pieterse, Heloise , Burke, Ivan , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429648 , vital:72629 , 10.1109/ICASTech.2013.6707509
- Description: Computer network attacks are difficult to simulate due to the damage they may cause to live networks and the complexity required simulating a useful network. We constructed a virtualised network within a vSphereESXi environment which is able to simulate: thirty workstations, ten servers, three distinct network segments and the accompanying network traffic. The VSphere environment provided added benefits, such as the ability to pause, restart and snapshot virtual computers. These abilities enabled the authors to reset the simulation environment before each test and mitigated against the damage that an attack potentially inflicts on the test network. Without simulated network traffic, the virtualised network was too sterile. This resulted in any network event being a simple task to detect, making network traffic simulation a requirement for an event detection test bed. Five main kinds of traffic were simulated: Web browsing, File transfer, e-mail, version control and Intranet File traffic. The simulated traffic volumes were pseudo randomised to represent differing temporal patterns. By building a virtualised network with simulated traffic we were able to test IDS' and other network attack detection sensors in a much more realistic environment before moving it to a live network. The goal of this paper is to present a virtualised testbedenvironmentin which network attacks can safely be tested.
- Full Text:
- Date Issued: 2013
Dispersal barriers and stochastic reproductive success do not explain small-scale genetic structure in a broadcast spawning marine mussel
- Teske, Peter R, Papadopoulos, Isabelle, Barker, Nigel P, McQuaid, Christopher D
- Authors: Teske, Peter R , Papadopoulos, Isabelle , Barker, Nigel P , McQuaid, Christopher D
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/445577 , vital:74403 , https://doi.org/10.3354/meps10230
- Description: Small-scale genetic heterogeneity in marine broadcast spawners is often attributed either to physical factors that constrain larval dispersal or to stochasticity in reproductive success. In females of the mussel Perna perna, it has been attributed to asymmetrical levels of gene flow between bays and the open coast, with bays acting as sources of propagules. If nearshore currents are an important feature constraining dispersal, then genetic heterogeneity should also be identified in other coastal invertebrates with similar dispersal potential, and the amount of genetic structure in adults and juveniles should be similar, whereas temporal changes in reproductive success should manifest themselves in lower genetic diversity of juveniles. We compared sequence data of female P. perna with that of males, juveniles and 3 sympatric marine invertebrates. Congruent genetic structure was only found in a direct developer, suggesting that the region’s oceanography does not have a strong structuring effect on species that, like female P. perna, have a planktonic dispersal phase. Furthermore, lack of genetic structure in male and juvenile P. perna indicates that there are no physical barriers that reduce larval exchange. Stochastic reproductive success is also an unlikely explanation for genetic structure in P. perna because levels of genetic diversity are similar in adults and juveniles. Together with the recent finding that the sex ratio in P. perna is skewed toward males, particularly at exposed coastal sites, these results point to a role for selection in driving genetic structure between bays and coastal habitats by eliminating a large proportion of adult females from the open coast.
- Full Text: false
- Date Issued: 2013
- Authors: Teske, Peter R , Papadopoulos, Isabelle , Barker, Nigel P , McQuaid, Christopher D
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/445577 , vital:74403 , https://doi.org/10.3354/meps10230
- Description: Small-scale genetic heterogeneity in marine broadcast spawners is often attributed either to physical factors that constrain larval dispersal or to stochasticity in reproductive success. In females of the mussel Perna perna, it has been attributed to asymmetrical levels of gene flow between bays and the open coast, with bays acting as sources of propagules. If nearshore currents are an important feature constraining dispersal, then genetic heterogeneity should also be identified in other coastal invertebrates with similar dispersal potential, and the amount of genetic structure in adults and juveniles should be similar, whereas temporal changes in reproductive success should manifest themselves in lower genetic diversity of juveniles. We compared sequence data of female P. perna with that of males, juveniles and 3 sympatric marine invertebrates. Congruent genetic structure was only found in a direct developer, suggesting that the region’s oceanography does not have a strong structuring effect on species that, like female P. perna, have a planktonic dispersal phase. Furthermore, lack of genetic structure in male and juvenile P. perna indicates that there are no physical barriers that reduce larval exchange. Stochastic reproductive success is also an unlikely explanation for genetic structure in P. perna because levels of genetic diversity are similar in adults and juveniles. Together with the recent finding that the sex ratio in P. perna is skewed toward males, particularly at exposed coastal sites, these results point to a role for selection in driving genetic structure between bays and coastal habitats by eliminating a large proportion of adult females from the open coast.
- Full Text: false
- Date Issued: 2013
Halting degradation of Southern Cape peatlands in agricultural landscapes
- Job, Nancy, Ellery, William F N
- Authors: Job, Nancy , Ellery, William F N
- Date: 2013
- Subjects: Peatlands -- South Africa -- Southern Cape Wetland ecology -- South Africa -- Southern Cape South Africa -- Social conditions
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/50013 , vital:25951
- Description: Palmiet peatlands in the agricultural landscape are viewed by farmers as problematic. They obstruct the effective passage of water along watercourses and therefore promote localized flooding of lands and infrastructure, and they trap sediment delivered along watercourses that drowns fields and infrastructure with sedimentary deposits. These events are problematic for farmers trying to make a living off the land. Wetlands are also often viewed as wastelands that should be put to more productive use. The obvious thing to do is to bring in machinery to drain the wetlands and improve the flow of water and sediment through these wetlands.
- Full Text:
- Date Issued: 2013
- Authors: Job, Nancy , Ellery, William F N
- Date: 2013
- Subjects: Peatlands -- South Africa -- Southern Cape Wetland ecology -- South Africa -- Southern Cape South Africa -- Social conditions
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/50013 , vital:25951
- Description: Palmiet peatlands in the agricultural landscape are viewed by farmers as problematic. They obstruct the effective passage of water along watercourses and therefore promote localized flooding of lands and infrastructure, and they trap sediment delivered along watercourses that drowns fields and infrastructure with sedimentary deposits. These events are problematic for farmers trying to make a living off the land. Wetlands are also often viewed as wastelands that should be put to more productive use. The obvious thing to do is to bring in machinery to drain the wetlands and improve the flow of water and sediment through these wetlands.
- Full Text:
- Date Issued: 2013
Implementation of AES-64 connection management for Ethernet Audio/Video Bridging devices
- Dibley, James, Foss, Richard
- Authors: Dibley, James , Foss, Richard
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426875 , vital:72397 , https://www.aes.org/e-lib/online/browse.cfm?elib=17014
- Description: AES-64 is a standard for the discovery, enumeration, connection management, and control of multimedia network devices. This paper describes the implementation of an AES-64 protocol stack and control application on devices that support the IEEE Ethernet Audio/Video Bridging standards for streaming multimedia, enabling connection management of network audio streams.
- Full Text:
- Date Issued: 2013
- Authors: Dibley, James , Foss, Richard
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426875 , vital:72397 , https://www.aes.org/e-lib/online/browse.cfm?elib=17014
- Description: AES-64 is a standard for the discovery, enumeration, connection management, and control of multimedia network devices. This paper describes the implementation of an AES-64 protocol stack and control application on devices that support the IEEE Ethernet Audio/Video Bridging standards for streaming multimedia, enabling connection management of network audio streams.
- Full Text:
- Date Issued: 2013
Insights from experimental economics on local cooperation in a small-scale fishery management system:
- Aswani, Shankar, Gurney, Georgina G, Mulville, Sara, Matera, Jaime, Gurven, Michael
- Authors: Aswani, Shankar , Gurney, Georgina G , Mulville, Sara , Matera, Jaime , Gurven, Michael
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145437 , vital:38438 , DOI: 10.1016/j.gloenvcha.2013.08.003
- Description: Cooperation is central to collective management of small-scale fisheries management, including marine protected areas. Thus an understanding of the factors influencing stakeholders’ propensity to cooperate to achieve shared benefits is essential to accomplishing successful collective fisheries management. In this paper we study stakeholders’ cooperative behavioral disposition and elucidate the role of various socio-economic factors in influencing it in the Roviana Lagoon, Western Solomon Islands. We employed a Public Goods Game from experimental economics tailored to mimic the problem of common pool fisheries management to elucidate peoples’ cooperative behavior. Using Ostrom's framework for analyzing social-ecological systems to guide our analysis, we examined how individual-scale variables (e.g., age, education, family size, ethnicity, occupational status, personal norms), in the context of village-scale variables (e.g., village, governance institutions, group coercive action), influence cooperative behavior, as indexed by game contribution. Ostrom's framework provides an effective window for conceptually peeling back the various socio-economic and governance layers which influence cooperation within these communities.
- Full Text:
- Date Issued: 2013
- Authors: Aswani, Shankar , Gurney, Georgina G , Mulville, Sara , Matera, Jaime , Gurven, Michael
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145437 , vital:38438 , DOI: 10.1016/j.gloenvcha.2013.08.003
- Description: Cooperation is central to collective management of small-scale fisheries management, including marine protected areas. Thus an understanding of the factors influencing stakeholders’ propensity to cooperate to achieve shared benefits is essential to accomplishing successful collective fisheries management. In this paper we study stakeholders’ cooperative behavioral disposition and elucidate the role of various socio-economic factors in influencing it in the Roviana Lagoon, Western Solomon Islands. We employed a Public Goods Game from experimental economics tailored to mimic the problem of common pool fisheries management to elucidate peoples’ cooperative behavior. Using Ostrom's framework for analyzing social-ecological systems to guide our analysis, we examined how individual-scale variables (e.g., age, education, family size, ethnicity, occupational status, personal norms), in the context of village-scale variables (e.g., village, governance institutions, group coercive action), influence cooperative behavior, as indexed by game contribution. Ostrom's framework provides an effective window for conceptually peeling back the various socio-economic and governance layers which influence cooperation within these communities.
- Full Text:
- Date Issued: 2013
Prevalence of sustainability reporting practices of a sample of listed companies on established and emerging stock exchanges
- Turk, Brendan K, Shackleton, Charlie M, Whittington-Jones, Kevin J
- Authors: Turk, Brendan K , Shackleton, Charlie M , Whittington-Jones, Kevin J
- Date: 2013
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/60995 , vital:27908 , DOI: https://doi.org/10.4102/sajems.v16i1.234
- Description: The business sector has a substantial role in addressing current environmental issues and concerns. Consequently, there is a growing adoption of corporate sustainability principles and practices across all market sectors. This study examined four developed and four emerging stock markets and the sustainability reporting practices of the top 20 and bottom 20 companies in each. The results illustrate that the developed market sector was more advanced in its corporate sustainability reporting, both in the proportion of companies issuing a sustainability report (approximately 60 per cent) and the proportion of company webpages dedicated to sustainability reporting. This difference was largely due to the effect of the top 20 companies. There was little difference between developed and developing markets when only the bottom 20 companies were considered, of which less than one-third provided sustainability reports. These results show that sustainability reporting is prevalent in both developed and developing markets, especially among market leading companies, but that overall, most developing markets have some catching up to do.
- Full Text:
- Date Issued: 2013
- Authors: Turk, Brendan K , Shackleton, Charlie M , Whittington-Jones, Kevin J
- Date: 2013
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/60995 , vital:27908 , DOI: https://doi.org/10.4102/sajems.v16i1.234
- Description: The business sector has a substantial role in addressing current environmental issues and concerns. Consequently, there is a growing adoption of corporate sustainability principles and practices across all market sectors. This study examined four developed and four emerging stock markets and the sustainability reporting practices of the top 20 and bottom 20 companies in each. The results illustrate that the developed market sector was more advanced in its corporate sustainability reporting, both in the proportion of companies issuing a sustainability report (approximately 60 per cent) and the proportion of company webpages dedicated to sustainability reporting. This difference was largely due to the effect of the top 20 companies. There was little difference between developed and developing markets when only the bottom 20 companies were considered, of which less than one-third provided sustainability reports. These results show that sustainability reporting is prevalent in both developed and developing markets, especially among market leading companies, but that overall, most developing markets have some catching up to do.
- Full Text:
- Date Issued: 2013
Synthesis and magnetic properties of a superparamagnetic nanocomposite pectin-magnetite nanocomposite
- Namanga, Jude, Foba, Josepha, Ndinteh, Derek T, Yufanyi, Divine M, Krause, Rui W M
- Authors: Namanga, Jude , Foba, Josepha , Ndinteh, Derek T , Yufanyi, Divine M , Krause, Rui W M
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125075 , vital:35726 , https://doi.org/10.1155/2013/137275
- Description: Magnetic nanocomposites composed of superparamagnetic magnetite nanoparticles in a pectin matrix were synthesized by anin situ coprecipitation method. The pectin matrix acted as a stabilizer and size control host for the magnetite nanoparticles(MNPs) ensuring particle size homogeneity. The effects of the different reactant ratios and nanocomposite drying conditions onthe magnetic properties were investigated. The nanocomposites were characterized by X-ray diffraction (XRD), scanning electronmicroscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), Fourier-transforminfrared (FT-IR) spectroscopy, and superconducting quantum interference device magnetometer (SQUID). Superparamagneticmagnetite nanoparticles with mean diameters of 9 and 13 nm were obtained, and the freeze-dried nanocomposites had a saturationmagnetization of 54 and 53 emu/g, respectivel
- Full Text:
- Date Issued: 2013
- Authors: Namanga, Jude , Foba, Josepha , Ndinteh, Derek T , Yufanyi, Divine M , Krause, Rui W M
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125075 , vital:35726 , https://doi.org/10.1155/2013/137275
- Description: Magnetic nanocomposites composed of superparamagnetic magnetite nanoparticles in a pectin matrix were synthesized by anin situ coprecipitation method. The pectin matrix acted as a stabilizer and size control host for the magnetite nanoparticles(MNPs) ensuring particle size homogeneity. The effects of the different reactant ratios and nanocomposite drying conditions onthe magnetic properties were investigated. The nanocomposites were characterized by X-ray diffraction (XRD), scanning electronmicroscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), Fourier-transforminfrared (FT-IR) spectroscopy, and superconducting quantum interference device magnetometer (SQUID). Superparamagneticmagnetite nanoparticles with mean diameters of 9 and 13 nm were obtained, and the freeze-dried nanocomposites had a saturationmagnetization of 54 and 53 emu/g, respectivel
- Full Text:
- Date Issued: 2013
The Essential Oil of Eucalyptus grandis W. Hill ex Maiden Inhibits Microbial Growth by Inducing Membrane Damage
- Soyingbe, Oluwagbemiga Sewanu, Oyedeji, Adebola, Basson, Albert Kortze, Opoku, Andy Rowland
- Authors: Soyingbe, Oluwagbemiga Sewanu , Oyedeji, Adebola , Basson, Albert Kortze , Opoku, Andy Rowland
- Date: 2013
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/11260/731 , vital:29666
- Description: Eucalyptus grandis is a medicinal plant which has been indicated by Zulu traditional healer in the treatment of respira- tory tract infections, bronchial infections, asthma and cough. The investigation of the essential oil of this plant could help to verify the rationale behind the use of the plant as a cure for these illnesses. Essential oil was hydro-distilled from the fresh leaves and characterised for the chemical constituents and bioactivity. The main constituents of the oil of the E. grandis are α-Pinene (29.69%), p-Cymene (19.89%), 1,8-cineole (12.80%), α-Terpineol (6.48%), Borneol (3.48%) and D-Limonene (3.14%). The essential oil of E. grandis showed high scavenging of DPPH and ABTS radicals, and was active against 13 of the 16 organisms tested with the MIC ranging from 0.625 mg - 5.0 mg/ml; the MBC value ranged from 2.5 mg - 10 mg/ml. The essential oil also inhibited the growth of 7 of the 8 antibiotic resistant bacteria tested, with MIC ranging from 5 mg/ml - 10 mg/ml. The DNA extracted from the affected microorganisms did not show any dam- age however, there was an increase of released cytosolic LDH activity. We conclude that the antibacterial activity of the essential oil was exhibited through cell membrane damage rather than the damage of the DNA. It is apparent that the bioactivity of the essential oil of E. grandis plays an important role in the plants’ use in folk medicine for the treatment of respiratory tract illnesses.
- Full Text:
- Date Issued: 2013
- Authors: Soyingbe, Oluwagbemiga Sewanu , Oyedeji, Adebola , Basson, Albert Kortze , Opoku, Andy Rowland
- Date: 2013
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/11260/731 , vital:29666
- Description: Eucalyptus grandis is a medicinal plant which has been indicated by Zulu traditional healer in the treatment of respira- tory tract infections, bronchial infections, asthma and cough. The investigation of the essential oil of this plant could help to verify the rationale behind the use of the plant as a cure for these illnesses. Essential oil was hydro-distilled from the fresh leaves and characterised for the chemical constituents and bioactivity. The main constituents of the oil of the E. grandis are α-Pinene (29.69%), p-Cymene (19.89%), 1,8-cineole (12.80%), α-Terpineol (6.48%), Borneol (3.48%) and D-Limonene (3.14%). The essential oil of E. grandis showed high scavenging of DPPH and ABTS radicals, and was active against 13 of the 16 organisms tested with the MIC ranging from 0.625 mg - 5.0 mg/ml; the MBC value ranged from 2.5 mg - 10 mg/ml. The essential oil also inhibited the growth of 7 of the 8 antibiotic resistant bacteria tested, with MIC ranging from 5 mg/ml - 10 mg/ml. The DNA extracted from the affected microorganisms did not show any dam- age however, there was an increase of released cytosolic LDH activity. We conclude that the antibacterial activity of the essential oil was exhibited through cell membrane damage rather than the damage of the DNA. It is apparent that the bioactivity of the essential oil of E. grandis plays an important role in the plants’ use in folk medicine for the treatment of respiratory tract illnesses.
- Full Text:
- Date Issued: 2013
Victimisation in the lives of lesbian-identified women in South Africa : implications for clinical assessment and treatment
- Padmanabhanunni, A, Edwards, David J A
- Authors: Padmanabhanunni, A , Edwards, David J A
- Date: 2013
- Language: English
- Type: Article
- Identifier: vital:6237 , http://hdl.handle.net/10962/d1007787
- Description: Few clinical studies have examined victimisation in the lives of lesbian women in South Africa and whether there are distinct implications for psychological treatment. This paper presents the assessment and treatment of a lesbian-identified South African survivor of childhood sexual abuse who, as an adult, was raped and later gang raped. Her victimisation in adulthood represented ‘corrective rape’ motivated by the prejudiced assumption that the sexuality of lesbian women is pathological and should be ‘corrected’ through rape. This paper lends insights into the role of heterosexism in shaping vulnerability to victimisation and the process of recovery. It provides recommendations for work with sexual minority clients and highlights the implications when there is an absence of safety and support in the external environment.
- Full Text:
- Date Issued: 2013
- Authors: Padmanabhanunni, A , Edwards, David J A
- Date: 2013
- Language: English
- Type: Article
- Identifier: vital:6237 , http://hdl.handle.net/10962/d1007787
- Description: Few clinical studies have examined victimisation in the lives of lesbian women in South Africa and whether there are distinct implications for psychological treatment. This paper presents the assessment and treatment of a lesbian-identified South African survivor of childhood sexual abuse who, as an adult, was raped and later gang raped. Her victimisation in adulthood represented ‘corrective rape’ motivated by the prejudiced assumption that the sexuality of lesbian women is pathological and should be ‘corrected’ through rape. This paper lends insights into the role of heterosexism in shaping vulnerability to victimisation and the process of recovery. It provides recommendations for work with sexual minority clients and highlights the implications when there is an absence of safety and support in the external environment.
- Full Text:
- Date Issued: 2013
Visualization of a data leak
- Swart, Ignus, Grobler, Marthie, Irwin, Barry V W
- Authors: Swart, Ignus , Grobler, Marthie , Irwin, Barry V W
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428584 , vital:72522 , 10.1109/ISSA.2013.6641046
- Description: The potential impact that data leakage can have on a country, both on a national level as well as on an individual level, can be wide reaching and potentially catastrophic. In January 2013, several South African companies became the target of a hack attack, resulting in the breach of security measures and the leaking of a claimed 700000 records. The affected companies are spread across a number of domains, thus making the leak a very wide impact area. The aim of this paper is to analyze the data released from the South African breach and to visualize the extent of the loss by the companies affected. The value of this work lies in its connection to and interpretation of related South African legislation. The data extracted during the analysis is primarily personally identifiable information, such as defined by the Electronic Communications and Transactions Act of 2002 and the Protection of Personal Information Bill of 2009.
- Full Text:
- Date Issued: 2013
- Authors: Swart, Ignus , Grobler, Marthie , Irwin, Barry V W
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428584 , vital:72522 , 10.1109/ISSA.2013.6641046
- Description: The potential impact that data leakage can have on a country, both on a national level as well as on an individual level, can be wide reaching and potentially catastrophic. In January 2013, several South African companies became the target of a hack attack, resulting in the breach of security measures and the leaking of a claimed 700000 records. The affected companies are spread across a number of domains, thus making the leak a very wide impact area. The aim of this paper is to analyze the data released from the South African breach and to visualize the extent of the loss by the companies affected. The value of this work lies in its connection to and interpretation of related South African legislation. The data extracted during the analysis is primarily personally identifiable information, such as defined by the Electronic Communications and Transactions Act of 2002 and the Protection of Personal Information Bill of 2009.
- Full Text:
- Date Issued: 2013
Walking The Other Side: Doung Anwar Jahangeer
- Authors: Simbao, Ruth K
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147681 , vital:38660 , https://0-doi.org.wam.seals.ac.za/10.1080/09528822.2013.796204
- Description: While certain forms of mobility are romanticized in the privileged worlds of art and academia, the need to move is often triggered by vulnerability, and literal pathways on the ground reveal much about human engagement with place. This article considers the work of Mauritian-born architect/artist/performer Doung Anwar Jahangeer who is based in Durban, South Africa. Inspired by Michel de Certeau, Jahangeer argues that pathways reveal the characteristics of society and uses the act of walking to question the degree to which meaningful transformation has taken place in South Africa. His City Walk performances disclose to audiences how grounded ways of engaging with movement can challenge the metaphoric blindness that handicaps privileged movement. Focusing on his performances from the 2012 ‘Making Way’ exhibition the author interprets Jahangeer's work as challenging blind spots with regard to space, particularly partial spaces still marred by Apartheid. Through performative walking he encourages his audiences to read between the lines of road markings, cracks and signs, and to experience the power of corporeally engaging with the road by thoughtfully placing one foot in front of the other as a mode of seeing.
- Full Text:
- Date Issued: 2013
- Authors: Simbao, Ruth K
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147681 , vital:38660 , https://0-doi.org.wam.seals.ac.za/10.1080/09528822.2013.796204
- Description: While certain forms of mobility are romanticized in the privileged worlds of art and academia, the need to move is often triggered by vulnerability, and literal pathways on the ground reveal much about human engagement with place. This article considers the work of Mauritian-born architect/artist/performer Doung Anwar Jahangeer who is based in Durban, South Africa. Inspired by Michel de Certeau, Jahangeer argues that pathways reveal the characteristics of society and uses the act of walking to question the degree to which meaningful transformation has taken place in South Africa. His City Walk performances disclose to audiences how grounded ways of engaging with movement can challenge the metaphoric blindness that handicaps privileged movement. Focusing on his performances from the 2012 ‘Making Way’ exhibition the author interprets Jahangeer's work as challenging blind spots with regard to space, particularly partial spaces still marred by Apartheid. Through performative walking he encourages his audiences to read between the lines of road markings, cracks and signs, and to experience the power of corporeally engaging with the road by thoughtfully placing one foot in front of the other as a mode of seeing.
- Full Text:
- Date Issued: 2013
What to expect when you’re not expecting : child-freedom, social stigma, and online subjectivities
- Authors: Morison, Tracy
- Date: 2013
- Language: English
- Type: Conference paper , text
- Identifier: vital:6210 , http://hdl.handle.net/10962/d1003915
- Description: From Introduction: Today I’m presenting some of the preliminary findings of a study about voluntary childlessness conducted with Indian, Polish, and fellow South African collaborators. Voluntary childlessness is also frequently referred to as being childless by choice or childfree. The term childfree (as opposed to ‘childless’) is intended to show that not having children “can be an active and fulfilling choice”, and to indicate agency and freedom from social obligation. The distinguishing feature of voluntary childlessness is the deliberate avoidance of parenthood, and this is precisely what opens up childfree people, especially married heterosexuals, to greater stigma than the temporarily or involuntarily childless, since it is seen as willing and deliberate deviation from the norm. Having children is seen as a natural consequence of being a “normal” heterosexual woman or man, as well as an expected outcome of marriage. Parenthood is therefore normalised by regulative discourses around sexuality and gender. This process of normalisation is reinforced by pronatalist discourse. According to Meyers, pronatalism rests upon twin strategies: The first is the valorisation or glorification of parenthood, which supports the belief that having children is the only true path to fulfilment. The second strategy is the denigration of non-reproduction in which childlessness is cast as horrific. The result of these dual strategies is to eliminate deliberate childlessness as a possibility. Parenthood, as the only truly viable option for a fulfilling life, is therefore a non-choice. This is compounded by nationalistic and religious rhetoric that constructs childbearing as an obligation or duty. Consequently, as my previous research showed, people often do not reflect on whether to have children or not, but see it more as a matter of timing.
- Full Text:
- Date Issued: 2013
- Authors: Morison, Tracy
- Date: 2013
- Language: English
- Type: Conference paper , text
- Identifier: vital:6210 , http://hdl.handle.net/10962/d1003915
- Description: From Introduction: Today I’m presenting some of the preliminary findings of a study about voluntary childlessness conducted with Indian, Polish, and fellow South African collaborators. Voluntary childlessness is also frequently referred to as being childless by choice or childfree. The term childfree (as opposed to ‘childless’) is intended to show that not having children “can be an active and fulfilling choice”, and to indicate agency and freedom from social obligation. The distinguishing feature of voluntary childlessness is the deliberate avoidance of parenthood, and this is precisely what opens up childfree people, especially married heterosexuals, to greater stigma than the temporarily or involuntarily childless, since it is seen as willing and deliberate deviation from the norm. Having children is seen as a natural consequence of being a “normal” heterosexual woman or man, as well as an expected outcome of marriage. Parenthood is therefore normalised by regulative discourses around sexuality and gender. This process of normalisation is reinforced by pronatalist discourse. According to Meyers, pronatalism rests upon twin strategies: The first is the valorisation or glorification of parenthood, which supports the belief that having children is the only true path to fulfilment. The second strategy is the denigration of non-reproduction in which childlessness is cast as horrific. The result of these dual strategies is to eliminate deliberate childlessness as a possibility. Parenthood, as the only truly viable option for a fulfilling life, is therefore a non-choice. This is compounded by nationalistic and religious rhetoric that constructs childbearing as an obligation or duty. Consequently, as my previous research showed, people often do not reflect on whether to have children or not, but see it more as a matter of timing.
- Full Text:
- Date Issued: 2013
An Analysis and Implementation of Methods for High Speed Lexical Classification of Malicious URLs
- Egan, Shaun P, Irwin, Barry V W
- Authors: Egan, Shaun P , Irwin, Barry V W
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429757 , vital:72637 , https://digifors.cs.up.ac.za/issa/2012/Proceedings/Research/58_ResearchInProgress.pdf
- Description: Several authors have put forward methods of using Artificial Neural Networks (ANN) to classify URLs as malicious or benign by using lexical features of those URLs. These methods have been compared to other methods of classification, such as blacklisting and spam filtering, and have been found to be as accurate. Early attempts proved to be as highly accurate. Fully featured classifications use lexical features as well as lookups to classify URLs and include (but are not limited to) blacklists, spam filters and reputation services. These classifiers are based on the Online Perceptron Model, using a single neuron as a linear combiner and used lexical features that rely on the presence (or lack thereof) of words belonging to a bag-of-words. Several obfuscation resistant features are also used to increase the positive classification rate of these perceptrons. Examples of these include URL length, number of directory traversals and length of arguments passed to the file within the URL. In this paper we describe how we implement the online perceptron model and methods that we used to try to increase the accuracy of this model through the use of hidden layers and training cost validation. We discuss our results in relation to those of other papers, as well as other analysis performed on the training data and the neural networks themselves to best understand why they are so effective. Also described will be the proposed model for developing these Neural Networks, how to implement them in the real world through the use of browser extensions, proxy plugins and spam filters for mail servers, and our current implementation. Finally, work that is still in progress will be described. This work includes other methods of increasing accuracy through the use of modern training techniques and testing in a real world environment.
- Full Text:
- Date Issued: 2012
- Authors: Egan, Shaun P , Irwin, Barry V W
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429757 , vital:72637 , https://digifors.cs.up.ac.za/issa/2012/Proceedings/Research/58_ResearchInProgress.pdf
- Description: Several authors have put forward methods of using Artificial Neural Networks (ANN) to classify URLs as malicious or benign by using lexical features of those URLs. These methods have been compared to other methods of classification, such as blacklisting and spam filtering, and have been found to be as accurate. Early attempts proved to be as highly accurate. Fully featured classifications use lexical features as well as lookups to classify URLs and include (but are not limited to) blacklists, spam filters and reputation services. These classifiers are based on the Online Perceptron Model, using a single neuron as a linear combiner and used lexical features that rely on the presence (or lack thereof) of words belonging to a bag-of-words. Several obfuscation resistant features are also used to increase the positive classification rate of these perceptrons. Examples of these include URL length, number of directory traversals and length of arguments passed to the file within the URL. In this paper we describe how we implement the online perceptron model and methods that we used to try to increase the accuracy of this model through the use of hidden layers and training cost validation. We discuss our results in relation to those of other papers, as well as other analysis performed on the training data and the neural networks themselves to best understand why they are so effective. Also described will be the proposed model for developing these Neural Networks, how to implement them in the real world through the use of browser extensions, proxy plugins and spam filters for mail servers, and our current implementation. Finally, work that is still in progress will be described. This work includes other methods of increasing accuracy through the use of modern training techniques and testing in a real world environment.
- Full Text:
- Date Issued: 2012
Building a Graphical Fuzzing Framework
- Zeisberger, Sascha, Irwin, Barry V W
- Authors: Zeisberger, Sascha , Irwin, Barry V W
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429772 , vital:72638 , https://digifors.cs.up.ac.za/issa/2012/Proceedings/Research/59_ResearchInProgress.pdf
- Description: Fuzz testing is a robustness testing technique that sends malformed data to an application’s input. This is to test an application’s behaviour when presented with input beyond its specification. The main difference between traditional testing techniques and fuzz testing is that in most traditional techniques an application is tested according to a specification and rated on how well the application conforms to that specification. Fuzz testing tests beyond the scope of a specification by intelligently generating values that may be interpreted by an application in an unintended manner. The use of fuzz testing has been more prevalent in academic and security communities despite showing success in production environments. To measure the effectiveness of fuzz testing, an experiment was conducted where several publicly available applications were fuzzed. In some instances, fuzz testing was able to force an application into an invalid state and it was concluded that fuzz testing is a relevant testing technique that could assist in developing more robust applications. This success prompted a further investigation into fuzz testing in order to compile a list of requirements that makes an effective fuzzer. The aforementioned investigation assisted in the design of a fuzz testing framework, the goal of which is to make the process more accessible to users outside of an academic and security environment. Design methodologies and justifications of said framework are discussed, focusing on the graphical user interface components as this aspect of the framework is used to increase the usability of the framework.
- Full Text:
- Date Issued: 2012
- Authors: Zeisberger, Sascha , Irwin, Barry V W
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429772 , vital:72638 , https://digifors.cs.up.ac.za/issa/2012/Proceedings/Research/59_ResearchInProgress.pdf
- Description: Fuzz testing is a robustness testing technique that sends malformed data to an application’s input. This is to test an application’s behaviour when presented with input beyond its specification. The main difference between traditional testing techniques and fuzz testing is that in most traditional techniques an application is tested according to a specification and rated on how well the application conforms to that specification. Fuzz testing tests beyond the scope of a specification by intelligently generating values that may be interpreted by an application in an unintended manner. The use of fuzz testing has been more prevalent in academic and security communities despite showing success in production environments. To measure the effectiveness of fuzz testing, an experiment was conducted where several publicly available applications were fuzzed. In some instances, fuzz testing was able to force an application into an invalid state and it was concluded that fuzz testing is a relevant testing technique that could assist in developing more robust applications. This success prompted a further investigation into fuzz testing in order to compile a list of requirements that makes an effective fuzzer. The aforementioned investigation assisted in the design of a fuzz testing framework, the goal of which is to make the process more accessible to users outside of an academic and security environment. Design methodologies and justifications of said framework are discussed, focusing on the graphical user interface components as this aspect of the framework is used to increase the usability of the framework.
- Full Text:
- Date Issued: 2012
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