Comparative electrocatalytic studies of nanocomposites of mixed and covalently linked multiwalled carbon nanotubes and 4-(4, 6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt (II)
- Nyoni, Stephen, Nyokong, Tebello
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189285 , vital:44834 , xlink:href="https://doi.org/10.1016/j.poly.2015.05.038"
- Description: Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards L-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite.
- Full Text:
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189285 , vital:44834 , xlink:href="https://doi.org/10.1016/j.poly.2015.05.038"
- Description: Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards L-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite.
- Full Text:
Comparisons of isotopic niche widths of some invasive and indigenous fauna in a South African river
- Hill, Jaclyn M, Jones, Roy W, Hill, Martin P, Weyl, Olaf L F
- Authors: Hill, Jaclyn M , Jones, Roy W , Hill, Martin P , Weyl, Olaf L F
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423711 , vital:72088 , xlink:href="https://doi.org/10.1111/fwb.12542"
- Description: Biological invasions threaten ecosystem integrity and bio-diversity, with numerous adverse implications for native flora and fauna. Established populations of two notorious freshwater invaders, the snail Tarebia granifera and the fish Pterygoplichthys disjunctivus, have been reported on three continents and are frequently predicted to be in di-rect competition with native species for dietary resources.
- Full Text:
- Authors: Hill, Jaclyn M , Jones, Roy W , Hill, Martin P , Weyl, Olaf L F
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423711 , vital:72088 , xlink:href="https://doi.org/10.1111/fwb.12542"
- Description: Biological invasions threaten ecosystem integrity and bio-diversity, with numerous adverse implications for native flora and fauna. Established populations of two notorious freshwater invaders, the snail Tarebia granifera and the fish Pterygoplichthys disjunctivus, have been reported on three continents and are frequently predicted to be in di-rect competition with native species for dietary resources.
- Full Text:
Condoms in pockets and HIV-free certificates: mother-daughter communication about sex and risk in a time of AIDS epidemic in South Africa
- Authors: Wilbraham, Lindy
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143693 , vital:38274 , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
- Description: Responsive to the perceived high risks of sexual coercion, unwanted pregnancy and HIV-infection of girls in particular, several South African sexual health promotion campaigns have used media targeting parents (mothers in particular) to instruct them on how sex should be talked about with young people to ‘risk-proof’ them. Such an instrumentalist public health discourse posits this intergenerational communication as an ‘ongoing discussion’ of events, feelings, issues and risk-safe practices around heterosexual sex negotiation. A Foucauldian view finds these conversational imperatives pitched against much-talked-about resistances to talking about sex; and the saturation with risk of ambivalent mothers and silent daughters. Mother-daughter communication about sex and sexualities – as an uneasy western ideal of attachment parenting – has tangled roots in psychoanalytic theory and feminisms where sex as the core of modern subjectivity is normalized, capacities for intimacy are trained, and affiliative sexuality is modelled in ways that balance the rights and responsibilities of sexual agency/citizenship. This paper begins with two narrative fragments from a sexual health campaign that addressed mothers and daughters, and recounts how these ‘stories’ produced derisive laughter when introduced into group discussions with young/older women. The paper follows two lines of exploration. Firstly, is western idealized fabrication of inter-subjectivity between mothers and daughters desirable and feasible in post-apartheid conditions of epidemic in South Africa? And secondly, what if the narratives of lives and experiences we offer by way of health education materials provoke uncertainties, gaps and interrogations about sex, mothering and communication, instead of offering homilies and solutions?
- Full Text:
- Authors: Wilbraham, Lindy
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143693 , vital:38274 , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
- Description: Responsive to the perceived high risks of sexual coercion, unwanted pregnancy and HIV-infection of girls in particular, several South African sexual health promotion campaigns have used media targeting parents (mothers in particular) to instruct them on how sex should be talked about with young people to ‘risk-proof’ them. Such an instrumentalist public health discourse posits this intergenerational communication as an ‘ongoing discussion’ of events, feelings, issues and risk-safe practices around heterosexual sex negotiation. A Foucauldian view finds these conversational imperatives pitched against much-talked-about resistances to talking about sex; and the saturation with risk of ambivalent mothers and silent daughters. Mother-daughter communication about sex and sexualities – as an uneasy western ideal of attachment parenting – has tangled roots in psychoanalytic theory and feminisms where sex as the core of modern subjectivity is normalized, capacities for intimacy are trained, and affiliative sexuality is modelled in ways that balance the rights and responsibilities of sexual agency/citizenship. This paper begins with two narrative fragments from a sexual health campaign that addressed mothers and daughters, and recounts how these ‘stories’ produced derisive laughter when introduced into group discussions with young/older women. The paper follows two lines of exploration. Firstly, is western idealized fabrication of inter-subjectivity between mothers and daughters desirable and feasible in post-apartheid conditions of epidemic in South Africa? And secondly, what if the narratives of lives and experiences we offer by way of health education materials provoke uncertainties, gaps and interrogations about sex, mothering and communication, instead of offering homilies and solutions?
- Full Text:
Constructing sexualities: a critical overview of articles published in Feminism and Psychology
- Marx, Jacqueline, Donaldson, Natalie
- Authors: Marx, Jacqueline , Donaldson, Natalie
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142040 , vital:38044 , DOI: 10.1177/0959353515572704
- Description: How have sexualities been dealt with in articles published in Feminism and Psychology since the inception of the journal in 1991? The idea for this overview arose from our experience of designing a critical sexualities course for graduate students in psychology. The articles featured in this overview form part of a Virtual Special Issue that can be located on the Feminism and Psychology website. Virtual Special Issues (VSI) are collections of previously published articles, which have been compiled by guest editors who are experts in the field. VSIs provide readers with an overview of feminist thought about a topic or theme, as well as an easy way to locate pertinent articles. Scholars who are approaching a new topic may find a VSI especially useful, as will instructors who are preparing course syllabi. This article introduces the Constructing Sexualities VSI.
- Full Text:
- Authors: Marx, Jacqueline , Donaldson, Natalie
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142040 , vital:38044 , DOI: 10.1177/0959353515572704
- Description: How have sexualities been dealt with in articles published in Feminism and Psychology since the inception of the journal in 1991? The idea for this overview arose from our experience of designing a critical sexualities course for graduate students in psychology. The articles featured in this overview form part of a Virtual Special Issue that can be located on the Feminism and Psychology website. Virtual Special Issues (VSI) are collections of previously published articles, which have been compiled by guest editors who are experts in the field. VSIs provide readers with an overview of feminist thought about a topic or theme, as well as an easy way to locate pertinent articles. Scholars who are approaching a new topic may find a VSI especially useful, as will instructors who are preparing course syllabi. This article introduces the Constructing Sexualities VSI.
- Full Text:
Counsellors’ constructions of intimate partner violence (IPV) during pregnancy and their interventions with women suffering such IPV:
- Fleischack, Anne, Macleod, Catriona I, Böhmke, Werner
- Authors: Fleischack, Anne , Macleod, Catriona I , Böhmke, Werner
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143716 , vital:38276 , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
- Description: South African research reveals a high prevalence of intimate partner violence (IPV) yet little research exists regarding IPV during pregnancy. In this paper we present data collected through narrative interviews with eight counsellors from two NGOs working with women experiencing IPV during pregnancy. Using a narrative-discursive analytical lens, attention was given to the construction of subject positions and power relations between the men and women in the counsellors’ narratives. Men were largely positioned as subscribing to violent patriarchal behaviour whilst women were mostly positioned as nurturing, and as victims. The counsellors saw IPV during pregnancy as occurring for a variety of reasons, including conflicts around abortion, and male partners finding the women physically unattractive. It was noted that IPV during pregnancy is managed by women in complex ways. Counsellors’ emphasis on individual counselling and leaving the IPV relationship suggests that women are ultimately responsible for their own wellbeing and success.
- Full Text:
- Authors: Fleischack, Anne , Macleod, Catriona I , Böhmke, Werner
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143716 , vital:38276 , https://ischp.files.wordpress.com/2015/08/ischp_2015_abstract_booklet.pdf
- Description: South African research reveals a high prevalence of intimate partner violence (IPV) yet little research exists regarding IPV during pregnancy. In this paper we present data collected through narrative interviews with eight counsellors from two NGOs working with women experiencing IPV during pregnancy. Using a narrative-discursive analytical lens, attention was given to the construction of subject positions and power relations between the men and women in the counsellors’ narratives. Men were largely positioned as subscribing to violent patriarchal behaviour whilst women were mostly positioned as nurturing, and as victims. The counsellors saw IPV during pregnancy as occurring for a variety of reasons, including conflicts around abortion, and male partners finding the women physically unattractive. It was noted that IPV during pregnancy is managed by women in complex ways. Counsellors’ emphasis on individual counselling and leaving the IPV relationship suggests that women are ultimately responsible for their own wellbeing and success.
- Full Text:
Current developments in arbuscular mycorrhizal fungi research and its role in salinity stress alleviation a biotechnological perspective
- Kumar, Ashwani, Dames, Joanna F, Gupta, Aditi, Sharma, Satyawati, Gilbert, Jack A, Ahmad, Parvaiz
- Authors: Kumar, Ashwani , Dames, Joanna F , Gupta, Aditi , Sharma, Satyawati , Gilbert, Jack A , Ahmad, Parvaiz
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443998 , vital:74177 , https://doi.org/10.3109/07388551.2014.899964
- Description: Arbuscular mycorrhizal fungi (AMF) form widespread symbiotic associations with 80% of known land plants. They play a major role in plant nutrition, growth, water absorption, nutrient cycling and protection from pathogens, and as a result, contribute to ecosystem processes. Salinity stress conditions undoubtedly limit plant productivity and, therefore, the role of AMF as a biological tool for improving plant salt stress tolerance, is gaining economic importance worldwide. However, this approach requires a better understanding of how plants and AMF intimately interact with each other in saline environments and how this interaction leads to physiological changes in plants. This knowledge is important to develop sustainable strategies for successful utilization of AMF to improve plant health under a variety of stress conditions. Recent advances in the field of molecular biology, “omics” technology and advanced microscopy can provide new insight about these mechanisms of interaction between AMF and plants, as well as other microbes. This review mainly discusses the effect of salinity on AMF and plants, and role of AMF in alleviation of salinity stress including insight on methods for AMF identification. The focus remains on latest advancements in mycorrhizal research that can potentially offer an integrative understanding of the role of AMF in salinity tolerance and sustainable crop production.
- Full Text:
- Authors: Kumar, Ashwani , Dames, Joanna F , Gupta, Aditi , Sharma, Satyawati , Gilbert, Jack A , Ahmad, Parvaiz
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443998 , vital:74177 , https://doi.org/10.3109/07388551.2014.899964
- Description: Arbuscular mycorrhizal fungi (AMF) form widespread symbiotic associations with 80% of known land plants. They play a major role in plant nutrition, growth, water absorption, nutrient cycling and protection from pathogens, and as a result, contribute to ecosystem processes. Salinity stress conditions undoubtedly limit plant productivity and, therefore, the role of AMF as a biological tool for improving plant salt stress tolerance, is gaining economic importance worldwide. However, this approach requires a better understanding of how plants and AMF intimately interact with each other in saline environments and how this interaction leads to physiological changes in plants. This knowledge is important to develop sustainable strategies for successful utilization of AMF to improve plant health under a variety of stress conditions. Recent advances in the field of molecular biology, “omics” technology and advanced microscopy can provide new insight about these mechanisms of interaction between AMF and plants, as well as other microbes. This review mainly discusses the effect of salinity on AMF and plants, and role of AMF in alleviation of salinity stress including insight on methods for AMF identification. The focus remains on latest advancements in mycorrhizal research that can potentially offer an integrative understanding of the role of AMF in salinity tolerance and sustainable crop production.
- Full Text:
Cyber Vulnerability Assessment: Case Study of Malawi and Tanzania
- Chindipha, Stones, D, Irwin, Barry V W
- Authors: Chindipha, Stones, D , Irwin, Barry V W
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428558 , vital:72520 , https://accconference.mandela.ac.za/ACCConference/media/Store/images/Proceedings-2015.pdf#page=105
- Description: Much as the Internet is beneficial to our daily activities, with each passing day it also brings along with it information security concerns for the users be they at company or national level. Each year the number of Internet users keeps growing, particularly in Africa, and this means only one thing, more cyber-attacks. Governments have become a focal point of this data leakage problem making this a matter of national security. Looking at the current state of affairs, cyber-based incidents are more likely to increase in Africa, mainly due to the increased prevalence and affordability of broadband connectivity which is coupled with lack of online security awareness. A drop in the cost of broadband connection means more people will be able to afford Internet connectivity. With open Source Intelligence (OSINT), this paper aims to perform a vulnerability analysis for states in Eastern Africa building from prior research by Swart et al. which showed that there are vulnerabilities in the information systems, using the case of South Africa as an example. States in East Africa are to be considered as candidates, with the final decision being determined by access to suitable resources, and availability of information. A comparative analysis to assess the factors that affect the degree of security susceptibilities in various states will also be made and information security measures used by various governments to ascertain the extent of their contribution to this vulnerability will be assessed. This pilot study will be extended to other Southern and Eastern African states like Botswana, Kenya, Uganda and Namibia in future work.
- Full Text:
- Authors: Chindipha, Stones, D , Irwin, Barry V W
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428558 , vital:72520 , https://accconference.mandela.ac.za/ACCConference/media/Store/images/Proceedings-2015.pdf#page=105
- Description: Much as the Internet is beneficial to our daily activities, with each passing day it also brings along with it information security concerns for the users be they at company or national level. Each year the number of Internet users keeps growing, particularly in Africa, and this means only one thing, more cyber-attacks. Governments have become a focal point of this data leakage problem making this a matter of national security. Looking at the current state of affairs, cyber-based incidents are more likely to increase in Africa, mainly due to the increased prevalence and affordability of broadband connectivity which is coupled with lack of online security awareness. A drop in the cost of broadband connection means more people will be able to afford Internet connectivity. With open Source Intelligence (OSINT), this paper aims to perform a vulnerability analysis for states in Eastern Africa building from prior research by Swart et al. which showed that there are vulnerabilities in the information systems, using the case of South Africa as an example. States in East Africa are to be considered as candidates, with the final decision being determined by access to suitable resources, and availability of information. A comparative analysis to assess the factors that affect the degree of security susceptibilities in various states will also be made and information security measures used by various governments to ascertain the extent of their contribution to this vulnerability will be assessed. This pilot study will be extended to other Southern and Eastern African states like Botswana, Kenya, Uganda and Namibia in future work.
- Full Text:
Data Centre vulnerabilities physical, logical and trusted entity security
- Swart, Ignus, Grobler, Marthie, Irwin, Barry V W
- Authors: Swart, Ignus , Grobler, Marthie , Irwin, Barry V W
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427859 , vital:72467 , https://www.researchgate.net/profile/Ignus-Swart/publication/305442546_Data_Centre_vulnerabilities_physical_logical_trusted_entity_security/links/578f38c108aecbca4cada6bf/Data-Centre-vulnerabilities-physical-logical-trusted-entity-security.pdf
- Description: Data centres are often the hub for a significant number of disparate interconnecting systems. With rapid advances in virtualization, the use of data centres have increased significantly and are set to continue growing. Systems hosted typically serve the data needs for a growing number of organizations ranging from private individuals to mammoth governmental departments. Due to this centralized method of operation, data centres have become a prime target for attackers. These attackers are not only after the data contained in the data centre but often the physical infrastructure the systems run on is the target of attack. Down time resulting from such an attack can affect a wide range of entities and can have severe financial implications for the owners of the data centre. To limit liability strict adherence to standards are prescribed. Technology however develops at a far faster pace than standards and our ability to accurately measure information security has significant hidden caveats. This allows for a situation where the defenders dilemma is exacerbated by information overload, a significant increase in attack surface and reporting tools that show only limited views. This paper investigates the logical and physical security components of a data centre and introduces the notion of third party involvement as an increase in attack surface due to the manner in which data centres typically operate.
- Full Text:
- Authors: Swart, Ignus , Grobler, Marthie , Irwin, Barry V W
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427859 , vital:72467 , https://www.researchgate.net/profile/Ignus-Swart/publication/305442546_Data_Centre_vulnerabilities_physical_logical_trusted_entity_security/links/578f38c108aecbca4cada6bf/Data-Centre-vulnerabilities-physical-logical-trusted-entity-security.pdf
- Description: Data centres are often the hub for a significant number of disparate interconnecting systems. With rapid advances in virtualization, the use of data centres have increased significantly and are set to continue growing. Systems hosted typically serve the data needs for a growing number of organizations ranging from private individuals to mammoth governmental departments. Due to this centralized method of operation, data centres have become a prime target for attackers. These attackers are not only after the data contained in the data centre but often the physical infrastructure the systems run on is the target of attack. Down time resulting from such an attack can affect a wide range of entities and can have severe financial implications for the owners of the data centre. To limit liability strict adherence to standards are prescribed. Technology however develops at a far faster pace than standards and our ability to accurately measure information security has significant hidden caveats. This allows for a situation where the defenders dilemma is exacerbated by information overload, a significant increase in attack surface and reporting tools that show only limited views. This paper investigates the logical and physical security components of a data centre and introduces the notion of third party involvement as an increase in attack surface due to the manner in which data centres typically operate.
- Full Text:
DDoS Attack Mitigation Through Control of Inherent Charge Decay of Memory Implementations
- Herbert, Alan, Irwin, Barry V W, van Heerden, Renier P
- Authors: Herbert, Alan , Irwin, Barry V W , van Heerden, Renier P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430339 , vital:72684 , https://www.academic-bookshop.com/ourshop/prod_3774091-ICCWS-2015-10th-International-Conference-on-Cyber-Warfare-and-Security-Kruger-National-Park-South-Africa-PRINT-ver-ISBN-978191030996.html
- Description: DDoS (Distributed Denial of Service) attacks over recent years have shown to be devastating on the target systems and services made publicly available over the Internet. Furthermore, the backscatter1 caused by DDoS attacks also affects the available bandwidth and responsiveness of many other hosts within the Internet. The unfortunate reality of these attacks is that the targeted party cannot fight back due to the presence of botnets and malware-driven hosts. These hosts that carry out the attack on a target are usually controlled remotely and the owner of the device is unaware of it; for this reason one cannot attack back directly as this will serve little more than to disable an innocent party. A proposed solution to these DDoS attacks is to identify a potential attacking address and ignore communication from that address for a set period of time through time stamping.
- Full Text:
- Authors: Herbert, Alan , Irwin, Barry V W , van Heerden, Renier P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430339 , vital:72684 , https://www.academic-bookshop.com/ourshop/prod_3774091-ICCWS-2015-10th-International-Conference-on-Cyber-Warfare-and-Security-Kruger-National-Park-South-Africa-PRINT-ver-ISBN-978191030996.html
- Description: DDoS (Distributed Denial of Service) attacks over recent years have shown to be devastating on the target systems and services made publicly available over the Internet. Furthermore, the backscatter1 caused by DDoS attacks also affects the available bandwidth and responsiveness of many other hosts within the Internet. The unfortunate reality of these attacks is that the targeted party cannot fight back due to the presence of botnets and malware-driven hosts. These hosts that carry out the attack on a target are usually controlled remotely and the owner of the device is unaware of it; for this reason one cannot attack back directly as this will serve little more than to disable an innocent party. A proposed solution to these DDoS attacks is to identify a potential attacking address and ignore communication from that address for a set period of time through time stamping.
- Full Text:
Deep genetic divergence between geographically isolated populations of the goldie barb (Barbus pallidus) in South Africa: potential taxonomic and conservation implications
- Chakona, Albert, Malherbe, Willem S, Gouws, Gavin, Swartz, Ernst R
- Authors: Chakona, Albert , Malherbe, Willem S , Gouws, Gavin , Swartz, Ernst R
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443284 , vital:74105 , https://hdl.handle.net/10520/EJC177698
- Description: Barbus pallidus as it is presently defined has a disjunct distribution that is divided between northern and southern populations in South Africa. Sequence data from the cytochrome b gene region showed two distinct lineages that correspond to these geographically distant areas. Divergence between these two lineages was relatively high (5.5-6.5%) and comparable to typical interspecific divergences found between closely related southern African cyprinid fishes. Based on this deep genetic divergence, we conclude that the northern lineage may represent a previously unrecognised species or may belong to a different, but known species or species complex not associated with 'true' B. pallidus. These findings add to a growing body of evidence that freshwater fish diversity in southern Africa requires major revision.
- Full Text:
- Authors: Chakona, Albert , Malherbe, Willem S , Gouws, Gavin , Swartz, Ernst R
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443284 , vital:74105 , https://hdl.handle.net/10520/EJC177698
- Description: Barbus pallidus as it is presently defined has a disjunct distribution that is divided between northern and southern populations in South Africa. Sequence data from the cytochrome b gene region showed two distinct lineages that correspond to these geographically distant areas. Divergence between these two lineages was relatively high (5.5-6.5%) and comparable to typical interspecific divergences found between closely related southern African cyprinid fishes. Based on this deep genetic divergence, we conclude that the northern lineage may represent a previously unrecognised species or may belong to a different, but known species or species complex not associated with 'true' B. pallidus. These findings add to a growing body of evidence that freshwater fish diversity in southern Africa requires major revision.
- Full Text:
Density and regrowth of a forest restio (Ischyrolepis eleocharis) under harvest and non-harvest treatments in dune forests of Eastern Cape Province, South Africa
- Ruwanza, Sheunesu, Shackleton, Charlie M
- Authors: Ruwanza, Sheunesu , Shackleton, Charlie M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180828 , vital:43649 , xlink:href="https://doi.org/10.1007/s12231-015-9306-y"
- Description: Ischyrolepis eleocharis (Mast.) H.P.Linder is a perennial rush or sedge-like herb in the Restionaceae family and has been harvested for various uses from coastal forest dunes of South Africa. Around 2005, a ban on I. eleocharis harvesting in Bathurst coastal forest was instituted by provincial conservation authorities based on their unsubstantiated impression that the species population was decreasing. Here we report on the population density pre and post the harvest ban, as well as further explore the autecology of the species by assessing plant density relative to environmental factors (slope and aspect) and a controlled experiment on regrowth after harvesting at different intensities. The results show that the shoot density of both living and dead I. eleocharis increased significantly over the past eight years. This concurs with results from the harvesting experiment which showed that I. eleocharis recovered rapidly within a year of harvesting. Both aspect and slope play a key role in the distribution of I. eleocharis, with most plants found in open patches in the forest located on the summit and upper slopes of dunes facing the landward side. These results indicate that I. eleocharis is highly abundant and resilient to harvesting.
- Full Text:
- Authors: Ruwanza, Sheunesu , Shackleton, Charlie M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180828 , vital:43649 , xlink:href="https://doi.org/10.1007/s12231-015-9306-y"
- Description: Ischyrolepis eleocharis (Mast.) H.P.Linder is a perennial rush or sedge-like herb in the Restionaceae family and has been harvested for various uses from coastal forest dunes of South Africa. Around 2005, a ban on I. eleocharis harvesting in Bathurst coastal forest was instituted by provincial conservation authorities based on their unsubstantiated impression that the species population was decreasing. Here we report on the population density pre and post the harvest ban, as well as further explore the autecology of the species by assessing plant density relative to environmental factors (slope and aspect) and a controlled experiment on regrowth after harvesting at different intensities. The results show that the shoot density of both living and dead I. eleocharis increased significantly over the past eight years. This concurs with results from the harvesting experiment which showed that I. eleocharis recovered rapidly within a year of harvesting. Both aspect and slope play a key role in the distribution of I. eleocharis, with most plants found in open patches in the forest located on the summit and upper slopes of dunes facing the landward side. These results indicate that I. eleocharis is highly abundant and resilient to harvesting.
- Full Text:
Design and Fabrication of a Low Cost Traffic Manipulation Hardware Platform
- Pennefather, Sean, Irwin, Barry V W
- Authors: Pennefather, Sean , Irwin, Barry V W
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427873 , vital:72468 , https://www.researchgate.net/profile/Barry-Ir-win/publication/327622941_Design_and_Fabrication_of_a_Low_Cost_Traffic_Manipulation_Hardware/links/5b9a1625458515310583fc8c/Design-and-Fabrication-of-a-Low-Cost-Traffic-Manipulation-Hardware.pdf
- Description: This paper describes the design and fabrication of a dedicated hardware platform for network traffic logging and modification at a production cost of under $300. The context of the device is briefly discussed before characteristics relating to hardware development are explored. The paper concludes with three application examples to show some to the potential functionality of the platform. Testing of the device shows an average TCP throughput of 84.44 MiB/s when using the designed Ethernet modules.
- Full Text:
- Authors: Pennefather, Sean , Irwin, Barry V W
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427873 , vital:72468 , https://www.researchgate.net/profile/Barry-Ir-win/publication/327622941_Design_and_Fabrication_of_a_Low_Cost_Traffic_Manipulation_Hardware/links/5b9a1625458515310583fc8c/Design-and-Fabrication-of-a-Low-Cost-Traffic-Manipulation-Hardware.pdf
- Description: This paper describes the design and fabrication of a dedicated hardware platform for network traffic logging and modification at a production cost of under $300. The context of the device is briefly discussed before characteristics relating to hardware development are explored. The paper concludes with three application examples to show some to the potential functionality of the platform. Testing of the device shows an average TCP throughput of 84.44 MiB/s when using the designed Ethernet modules.
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DNA-based identification of Lepidoptera associated with citrus in South Africa
- Marsberg, Tamryn, Hill, Martin P, Moore, Sean D, Timm, Alicia E
- Authors: Marsberg, Tamryn , Hill, Martin P , Moore, Sean D , Timm, Alicia E
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405782 , vital:70205 , xlink:href="https://hdl.handle.net/10520/EJC167513"
- Description: A number of insects, primarily Lepidoptera, cause damage to citrus in South Africa. A major limitation to the management and control of these pests is their correct identification. The aim of this study was to develop a database of gene sequences to aid in the identification of these Lepidoptera. Multiple specimens of 12 species were sequenced for the ~650 bp of the cytochrome oxidase I gene. These sequence data were supplemented and validated using sequences available in public databases. Results showed that each species could be unambiguously identified, and neighbour-joining analysis based on K2P distances formed highly supported, distinct clusters for each species, i.e. the maximum intraspecific genetic distance was less than that of the minimum interspecific genetic distances. Thus, this data set provides a molecular means to successfully identify the most important Lepidoptera associated with citrus in South Africa.
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- Authors: Marsberg, Tamryn , Hill, Martin P , Moore, Sean D , Timm, Alicia E
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405782 , vital:70205 , xlink:href="https://hdl.handle.net/10520/EJC167513"
- Description: A number of insects, primarily Lepidoptera, cause damage to citrus in South Africa. A major limitation to the management and control of these pests is their correct identification. The aim of this study was to develop a database of gene sequences to aid in the identification of these Lepidoptera. Multiple specimens of 12 species were sequenced for the ~650 bp of the cytochrome oxidase I gene. These sequence data were supplemented and validated using sequences available in public databases. Results showed that each species could be unambiguously identified, and neighbour-joining analysis based on K2P distances formed highly supported, distinct clusters for each species, i.e. the maximum intraspecific genetic distance was less than that of the minimum interspecific genetic distances. Thus, this data set provides a molecular means to successfully identify the most important Lepidoptera associated with citrus in South Africa.
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Dynamic mitochondrial localisation of STAT3 in the cellular adipogenesis model 3T3-L1:
- Kramer, Adam H, Edkins, Adrienne L, Hoppe, Heinrich C, Prinsloo, Earl
- Authors: Kramer, Adam H , Edkins, Adrienne L , Hoppe, Heinrich C , Prinsloo, Earl
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/164885 , vital:41181 , DOI: 10.1002/jcb.25076
- Description: A mechanistic relationship exists between protein localisation, activity and cellular differentiation. Understanding the contribution of these molecular mechanisms is required for elucidation of conditions that drive development. Literature suggests non‐canonical translocation of the Signal Transducer and Activator of Transcription 3 (STAT3) to the mitochondria contributes to the regulation of the electron transport chain, cellular respiration and reactive oxygen species production. Based on this we investigated the role of mitochondrial STAT3, specifically the serine 727 phosphorylated form, in cellular differentiation using the well‐defined mouse adipogenic model 3T3-L1.
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- Authors: Kramer, Adam H , Edkins, Adrienne L , Hoppe, Heinrich C , Prinsloo, Earl
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/164885 , vital:41181 , DOI: 10.1002/jcb.25076
- Description: A mechanistic relationship exists between protein localisation, activity and cellular differentiation. Understanding the contribution of these molecular mechanisms is required for elucidation of conditions that drive development. Literature suggests non‐canonical translocation of the Signal Transducer and Activator of Transcription 3 (STAT3) to the mitochondria contributes to the regulation of the electron transport chain, cellular respiration and reactive oxygen species production. Based on this we investigated the role of mitochondrial STAT3, specifically the serine 727 phosphorylated form, in cellular differentiation using the well‐defined mouse adipogenic model 3T3-L1.
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Editorial. Perspectives on transformations in learning and education
- Authors: Lotz-Sisitka, Heila
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387277 , vital:68221 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137656"
- Description: Perspectives on transformations in learning and education
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- Authors: Lotz-Sisitka, Heila
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387277 , vital:68221 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137656"
- Description: Perspectives on transformations in learning and education
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Effect of conventional and organic orchard floor management practices on arbuscular mycorrhizal fungi in a ‘Cripp’s Pink’/M7 apple orchard soil
- Meyer, André H, Wooldridge, John, Dames, Joanna F
- Authors: Meyer, André H , Wooldridge, John , Dames, Joanna F
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444012 , vital:74178 , https://doi.org/10.1016/j.agee.2015.07.026
- Description: Arbuscular mycorrhizal (AM) fungi are key components of agricultural soil–plant systems, which may be affected by agricultural practices. In organically managed (ORG) orchards, nutrients are supplied in the form of compost, and weeds are suppressed with mulches, whereas synthetic fertilizers and herbicides are used for these respective purposes in conventional (CON) orchards. The effects of ORG and CON orchard floor management practices on native AM fungi in apple orchards were investigated in a randomized field trial. AM root colonization, spore abundance, infectivity potentials and soil glomalin contents were determined in the 0–30 cm soil depth interval, in tree rows, over consecutive seasons. Root colonization was higher in the ORG than the CON treatments, but intermediate where straw mulch was substituted for green work-row covers. Glomalin levels were not affected by the treatments. Root colonization by AM fungi increased with increasing soil pH, P, C, K, Zn, and Mn concentrations, but were suppressed by Cu. Colonization correlated positively with leaf P, Ca and Mg, and with stem circumference, but negatively with leaf N and yield. ORG orchard floor management practices therefore, promoted functional AM associations more effectively than CON practices.
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- Authors: Meyer, André H , Wooldridge, John , Dames, Joanna F
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444012 , vital:74178 , https://doi.org/10.1016/j.agee.2015.07.026
- Description: Arbuscular mycorrhizal (AM) fungi are key components of agricultural soil–plant systems, which may be affected by agricultural practices. In organically managed (ORG) orchards, nutrients are supplied in the form of compost, and weeds are suppressed with mulches, whereas synthetic fertilizers and herbicides are used for these respective purposes in conventional (CON) orchards. The effects of ORG and CON orchard floor management practices on native AM fungi in apple orchards were investigated in a randomized field trial. AM root colonization, spore abundance, infectivity potentials and soil glomalin contents were determined in the 0–30 cm soil depth interval, in tree rows, over consecutive seasons. Root colonization was higher in the ORG than the CON treatments, but intermediate where straw mulch was substituted for green work-row covers. Glomalin levels were not affected by the treatments. Root colonization by AM fungi increased with increasing soil pH, P, C, K, Zn, and Mn concentrations, but were suppressed by Cu. Colonization correlated positively with leaf P, Ca and Mg, and with stem circumference, but negatively with leaf N and yield. ORG orchard floor management practices therefore, promoted functional AM associations more effectively than CON practices.
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Effect of temperature on development of the blowfly, Lucilia cuprina (Wiedemann)(Diptera: Calliphoridae)
- Kotzé, Zanthé, Villet, Martin H, Weldon, Christopher W
- Authors: Kotzé, Zanthé , Villet, Martin H , Weldon, Christopher W
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442116 , vital:73960 , https://doi.org/10.1007/s00414-015-1153-y
- Description: The blowfly Lucilia cuprina is a primary colonizer of decaying vertebrate carrion, and its development provides a temperature-dependent clock that may be used to estimate the post-mortem interval of corpses and carcasses in medicolegal forensic investigations. This study uses the development of L. cuprina raised on a substrate of chicken liver at six constant temperatures from 18 to 33 °C to calibrate a thermal accumulation model of development for forensic applications. Development was optimal near 24 °C; above this temperature, survival of post-feeding life stages was increasingly compromised, while below it, development was increasingly retarded. The lower developmental threshold (~12 °C) and thermal summation constants of L. cuprina are distinct from those reported for Lucilia sericata, verifying that it is essential to identify African Lucilia specimens accurately when using them to estimate post-mortem intervals.
- Full Text:
- Authors: Kotzé, Zanthé , Villet, Martin H , Weldon, Christopher W
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442116 , vital:73960 , https://doi.org/10.1007/s00414-015-1153-y
- Description: The blowfly Lucilia cuprina is a primary colonizer of decaying vertebrate carrion, and its development provides a temperature-dependent clock that may be used to estimate the post-mortem interval of corpses and carcasses in medicolegal forensic investigations. This study uses the development of L. cuprina raised on a substrate of chicken liver at six constant temperatures from 18 to 33 °C to calibrate a thermal accumulation model of development for forensic applications. Development was optimal near 24 °C; above this temperature, survival of post-feeding life stages was increasingly compromised, while below it, development was increasingly retarded. The lower developmental threshold (~12 °C) and thermal summation constants of L. cuprina are distinct from those reported for Lucilia sericata, verifying that it is essential to identify African Lucilia specimens accurately when using them to estimate post-mortem intervals.
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Effects of differently shaped silver nanoparticles on the photophysics of pyridylsulfanyl-substituted phthalocyanines
- D'Souza, Sarah, Mashazi, Philani N, Britton, Jonathan, Nyokong, Tebello
- Authors: D'Souza, Sarah , Mashazi, Philani N , Britton, Jonathan , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193564 , vital:45348 , xlink:href="https://doi.org/10.1016/j.poly.2015.06.038"
- Description: This paper reports on the photophysical behavior of (2-pyridylsulfanyl)phthalocyaninato zinc(II) and 2,9(10),16(17),23(24)-tetra-(2-pyridylsulfanyl)phthalocyaninato zinc(II) in the presence of differently shaped silver nanoparticles (nanospheres, nanotriangles and nanoflowers). The presence of shaped nanoparticles increased both triplet quantum yields and lifetimes of the tetra-substituted mercaptopyridine zinc phthalocyanine in DMSO. It is apparent from this work that the shape of the silver nanoparticle used is of little consequence in influencing photophysical behavior of the phthalocyanines.
- Full Text:
- Authors: D'Souza, Sarah , Mashazi, Philani N , Britton, Jonathan , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193564 , vital:45348 , xlink:href="https://doi.org/10.1016/j.poly.2015.06.038"
- Description: This paper reports on the photophysical behavior of (2-pyridylsulfanyl)phthalocyaninato zinc(II) and 2,9(10),16(17),23(24)-tetra-(2-pyridylsulfanyl)phthalocyaninato zinc(II) in the presence of differently shaped silver nanoparticles (nanospheres, nanotriangles and nanoflowers). The presence of shaped nanoparticles increased both triplet quantum yields and lifetimes of the tetra-substituted mercaptopyridine zinc phthalocyanine in DMSO. It is apparent from this work that the shape of the silver nanoparticle used is of little consequence in influencing photophysical behavior of the phthalocyanines.
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Effects of inoculating Lachnum and Cadophora isolates on the growth of Vaccinium corymbosum
- MBizabani, Christine, Dames, Joanna F
- Authors: MBizabani, Christine , Dames, Joanna F
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444024 , vital:74179 , https://doi.org/10.1016/j.micres.2015.08.005
- Description: The roots of ericaceous plants harbour a diversity of fungal taxa, which confer eco-physiological benefits to the host. Some of the fungi have been established to form ericoid mycorrhizal (ERM) associations and enhance plant growth in certain ericaceous genera. Although, Lachnum and Cadophora isolates have frequently been identified from the roots of this family, the status of their association and functional roles is still vague. The aims of this study were to identify Lachnum and Cadophora isolates; determine the root-fungal interactive structures formed in associations with Vaccinium corymbosum L. (blueberry) hosts and to examine inoculation effects of the fungal associates using several varieties of the blueberry. Lachnum and Cadophora were isolated and identified from Erica cerinthoides L. and Erica demmissa Klotzsch ex Benth using morphological and molecular techniques. Micropropagated blueberry varieties (Bluecrop, Elliott, Spartan, Chandler and Brightwell) were inoculated with respective fungi and plant growth evaluated. Both fungi colonised the roots and did not have any pathogenic effect.
- Full Text:
- Authors: MBizabani, Christine , Dames, Joanna F
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444024 , vital:74179 , https://doi.org/10.1016/j.micres.2015.08.005
- Description: The roots of ericaceous plants harbour a diversity of fungal taxa, which confer eco-physiological benefits to the host. Some of the fungi have been established to form ericoid mycorrhizal (ERM) associations and enhance plant growth in certain ericaceous genera. Although, Lachnum and Cadophora isolates have frequently been identified from the roots of this family, the status of their association and functional roles is still vague. The aims of this study were to identify Lachnum and Cadophora isolates; determine the root-fungal interactive structures formed in associations with Vaccinium corymbosum L. (blueberry) hosts and to examine inoculation effects of the fungal associates using several varieties of the blueberry. Lachnum and Cadophora were isolated and identified from Erica cerinthoides L. and Erica demmissa Klotzsch ex Benth using morphological and molecular techniques. Micropropagated blueberry varieties (Bluecrop, Elliott, Spartan, Chandler and Brightwell) were inoculated with respective fungi and plant growth evaluated. Both fungi colonised the roots and did not have any pathogenic effect.
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Effects of ZnO nanohexagons and nanorods on the fluorescence behavior of metallophthalocyanines
- D'Souza, Sarah, Moeno, Sharon, Nyokong, Tebello
- Authors: D'Souza, Sarah , Moeno, Sharon , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189741 , vital:44927 , xlink:href="https://doi.org/10.1016/j.poly.2014.09.012"
- Description: This paper looks at the fluorescence behavior of zinc phthalocyanines: 2,(3),9(10),16(17),23(24)-tetrakis- (mercaptoacetic acid phthalocyaninato) zinc(II) (ZnTMAAPc), 2,(3),9(10),16(17),23(24)-tetrakis-(mercaptopropanoic acid phthalocyaninato) zinc(II) (ZnTMPAPc) and (OH)AlPcSmix (the latter contains a mixture of the di-, tri- and tetra-sulfonated derivatives with an average of three sulfonated groups per molecule) in the presence of ZnO nanoparticles. Fluorescence lifetimes of Pc complexes generally decreased in the presence of ZnO nanoparticles, with generally longer lifetimes for ZnO nanohexagons compared to ZnO nanorods.
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- Authors: D'Souza, Sarah , Moeno, Sharon , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189741 , vital:44927 , xlink:href="https://doi.org/10.1016/j.poly.2014.09.012"
- Description: This paper looks at the fluorescence behavior of zinc phthalocyanines: 2,(3),9(10),16(17),23(24)-tetrakis- (mercaptoacetic acid phthalocyaninato) zinc(II) (ZnTMAAPc), 2,(3),9(10),16(17),23(24)-tetrakis-(mercaptopropanoic acid phthalocyaninato) zinc(II) (ZnTMPAPc) and (OH)AlPcSmix (the latter contains a mixture of the di-, tri- and tetra-sulfonated derivatives with an average of three sulfonated groups per molecule) in the presence of ZnO nanoparticles. Fluorescence lifetimes of Pc complexes generally decreased in the presence of ZnO nanoparticles, with generally longer lifetimes for ZnO nanohexagons compared to ZnO nanorods.
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