An investigation into electronic-source plagiarism in a first-year essay assignment
- Authors: Ellery, Karen
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/70114 , vital:29621 , https://doi.org/10.1080/02602930701772788
- Description: Since the emergence of the electronic era, plagiarism has become an increasingly prevalent problem at tertiary institutions. This study investigated the role electronic sources of information played in influencing plagiarism in an essay assignment in a first-year geography module at the University of KwaZulu-Natal in South Africa. Despite explicit instruction in tutorials on academic writing, referencing and plagiarism, a quarter of students still plagiarised in their essay, with the majority having done so off the Internet. A survey questionnaire and interviews revealed that not only did the school writing experience prepare students poorly for academic writing discourses, but also highlighted that student ignorance with regard to acknowledgement of electronic sources, a pervasive perception of difference between electronic and print sources, as well as the availability of the copy-and-paste facility which reinforces the product view of writing, all contributed towards electronic-source plagiarism. Active instructional engagement with electronic-source material, and open dialogue on ownership of knowledge as well as on moral and ethical issues with students, are recommended as strategies to overcome such plagiarism.
- Full Text:
- Date Issued: 2008
- Authors: Ellery, Karen
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/70114 , vital:29621 , https://doi.org/10.1080/02602930701772788
- Description: Since the emergence of the electronic era, plagiarism has become an increasingly prevalent problem at tertiary institutions. This study investigated the role electronic sources of information played in influencing plagiarism in an essay assignment in a first-year geography module at the University of KwaZulu-Natal in South Africa. Despite explicit instruction in tutorials on academic writing, referencing and plagiarism, a quarter of students still plagiarised in their essay, with the majority having done so off the Internet. A survey questionnaire and interviews revealed that not only did the school writing experience prepare students poorly for academic writing discourses, but also highlighted that student ignorance with regard to acknowledgement of electronic sources, a pervasive perception of difference between electronic and print sources, as well as the availability of the copy-and-paste facility which reinforces the product view of writing, all contributed towards electronic-source plagiarism. Active instructional engagement with electronic-source material, and open dialogue on ownership of knowledge as well as on moral and ethical issues with students, are recommended as strategies to overcome such plagiarism.
- Full Text:
- Date Issued: 2008
Spam Construction Trends
- Irwin, Barry V W, Friedman, Blake
- Authors: Irwin, Barry V W , Friedman, Blake
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428762 , vital:72534 , https://www.researchgate.net/profile/Barry-Ir-win/publication/220803159_Spam_Construction_Trends/links/53fc76bd0cf2dca8ffff22fb/Spam-Construction-Trends.pdf
- Description: This paper replicates and extends Observed Trends in Spam Construction Tech-niques: A Case Study of Spam Evolution. A corpus of 169,274 spam email was col-lected over a period of five years. Each spam email was tested for construction techniques using SpamAssassin’s spamicity tests. The results of these tests were col-lected in a database. Formal definitions of Pu and Webb’s co-existence, extinction and complex trends were developed and applied to the results within the database. A comparison of the Spam Evolution Study and this paper’s results took place to de-termine the relevance of the trends. A geolocation analysis was conducted on the corpus, as an extension, to determine the major geographic sources of the corpus.
- Full Text:
- Date Issued: 2008
- Authors: Irwin, Barry V W , Friedman, Blake
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428762 , vital:72534 , https://www.researchgate.net/profile/Barry-Ir-win/publication/220803159_Spam_Construction_Trends/links/53fc76bd0cf2dca8ffff22fb/Spam-Construction-Trends.pdf
- Description: This paper replicates and extends Observed Trends in Spam Construction Tech-niques: A Case Study of Spam Evolution. A corpus of 169,274 spam email was col-lected over a period of five years. Each spam email was tested for construction techniques using SpamAssassin’s spamicity tests. The results of these tests were col-lected in a database. Formal definitions of Pu and Webb’s co-existence, extinction and complex trends were developed and applied to the results within the database. A comparison of the Spam Evolution Study and this paper’s results took place to de-termine the relevance of the trends. A geolocation analysis was conducted on the corpus, as an extension, to determine the major geographic sources of the corpus.
- Full Text:
- Date Issued: 2008
A novel biosensor for the detection and monitoring of -d-galactosidase of faecal origin in water
- Wutor, V C, Togo, C A, Limson, Janice L, Pletschke, Brett I
- Authors: Wutor, V C , Togo, C A , Limson, Janice L , Pletschke, Brett I
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6468 , http://hdl.handle.net/10962/d1005797 , http://dx.doi.org/10.1016/j.enzmictec.2006.10.039
- Description: A voltammetric sensor prepared by the immobilization of metallophthalocyanine complexes onto a glassy carbon electrode has been developed for the detection of β-d-galactosidase (B-GAL) of faecal origin in water. Electrooxidation of chlorophenol red, a breakdown product of the chromogenic substrate chlorophenol red β-d-galactopyranoside, was used as a measure of β-d-galactosidase activity. At metallophthalocyanine modified electrodes, in particular copper(II) phthalocyanine, a decrease in electrode fouling was observed. The sensor was sensitive to fluctuations in pH, not significantly affected by temperature variations and could detect one colony forming unit/100 mL in 15 min. Loss of 40% sensitivity was observed over a period of 30 days. A strong correlation between sensor sensitivity and colony forming units was observed. The sensor is capable of detecting viable but nonculturable bacteria, overcoming this drawback of the use of culture media for detection of coliforms.
- Full Text:
- Date Issued: 2007
- Authors: Wutor, V C , Togo, C A , Limson, Janice L , Pletschke, Brett I
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6468 , http://hdl.handle.net/10962/d1005797 , http://dx.doi.org/10.1016/j.enzmictec.2006.10.039
- Description: A voltammetric sensor prepared by the immobilization of metallophthalocyanine complexes onto a glassy carbon electrode has been developed for the detection of β-d-galactosidase (B-GAL) of faecal origin in water. Electrooxidation of chlorophenol red, a breakdown product of the chromogenic substrate chlorophenol red β-d-galactopyranoside, was used as a measure of β-d-galactosidase activity. At metallophthalocyanine modified electrodes, in particular copper(II) phthalocyanine, a decrease in electrode fouling was observed. The sensor was sensitive to fluctuations in pH, not significantly affected by temperature variations and could detect one colony forming unit/100 mL in 15 min. Loss of 40% sensitivity was observed over a period of 30 days. A strong correlation between sensor sensitivity and colony forming units was observed. The sensor is capable of detecting viable but nonculturable bacteria, overcoming this drawback of the use of culture media for detection of coliforms.
- Full Text:
- Date Issued: 2007
Growth of Aloe ferox Mill. at selected sites in the Makana region of the Eastern Cape
- Shackleton, Charlie M, Gambiza, James
- Authors: Shackleton, Charlie M , Gambiza, James
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6654 , http://hdl.handle.net/10962/d1007068
- Description: There is widespread harvesting of the leaves of Aloe ferox to supply bitters and gel for cosmetic and health products. Government and private agencies are interested in expanding the industry as a means of providing income for poor rural communities. With the growing interest in the commercial use of A. ferox it is important that harvesting programmes are based on an adequate understanding of the ecology and productivity of the species, which will underpin estimates of possible sustainable yields. In this paper we report mean annual growth rates of 283 A. ferox plants (at six sites) during the 2005/2006 season. Growth was variable across sites and plant height. In terms of sites, the mean height growth ranged between 1.7 cm per plant per year at site 4 and 4.6 cm at site 2. The mean height increment across all sites and plants was 2.8 ± 0.2 cm. Plant height had a strong effect on annual increment with small plants (< 6 cm) more than doubling their height in the 12 month period, whereas plants taller than 2 m grew by approximately 1% over the year. Across the five unburnt sites, the mean standing stock of leaves grew by two per plant. The proportion of plants flowering increased progressively with plant height. Most (90%) of the plants that flowered in 2005 did so again in 2006.
- Full Text:
- Date Issued: 2007
- Authors: Shackleton, Charlie M , Gambiza, James
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6654 , http://hdl.handle.net/10962/d1007068
- Description: There is widespread harvesting of the leaves of Aloe ferox to supply bitters and gel for cosmetic and health products. Government and private agencies are interested in expanding the industry as a means of providing income for poor rural communities. With the growing interest in the commercial use of A. ferox it is important that harvesting programmes are based on an adequate understanding of the ecology and productivity of the species, which will underpin estimates of possible sustainable yields. In this paper we report mean annual growth rates of 283 A. ferox plants (at six sites) during the 2005/2006 season. Growth was variable across sites and plant height. In terms of sites, the mean height growth ranged between 1.7 cm per plant per year at site 4 and 4.6 cm at site 2. The mean height increment across all sites and plants was 2.8 ± 0.2 cm. Plant height had a strong effect on annual increment with small plants (< 6 cm) more than doubling their height in the 12 month period, whereas plants taller than 2 m grew by approximately 1% over the year. Across the five unburnt sites, the mean standing stock of leaves grew by two per plant. The proportion of plants flowering increased progressively with plant height. Most (90%) of the plants that flowered in 2005 did so again in 2006.
- Full Text:
- Date Issued: 2007
Making visible constructions of dis/advantage through genealogical investigation: South African schooled literacies
- Authors: Prinsloo, Jeanne
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147869 , vital:38680 , DOI: 10.1080/02560040701398889
- Description: In this paper I assume the relevance of Foucauldian insights for conducting socio-cultural critique and I argue the significance of genealogical work in relation to understanding the present. Thus, I seek both to establish what could constitute a genealogical investigation and to illustrate this by describing and discussing a study, undertaken within a genealogical frame, into literacy practices within a specifically South African context. I investigated the differing schooled literacies in KwaZulu-Natal province in South Africa over three decades along the language lines of Afrikaans, English and Zulu. The findings propose that the differing sets of literacy practices validate different subjects – and that they are implicated in constructing dis/advantage.
- Full Text:
- Date Issued: 2007
- Authors: Prinsloo, Jeanne
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147869 , vital:38680 , DOI: 10.1080/02560040701398889
- Description: In this paper I assume the relevance of Foucauldian insights for conducting socio-cultural critique and I argue the significance of genealogical work in relation to understanding the present. Thus, I seek both to establish what could constitute a genealogical investigation and to illustrate this by describing and discussing a study, undertaken within a genealogical frame, into literacy practices within a specifically South African context. I investigated the differing schooled literacies in KwaZulu-Natal province in South Africa over three decades along the language lines of Afrikaans, English and Zulu. The findings propose that the differing sets of literacy practices validate different subjects – and that they are implicated in constructing dis/advantage.
- Full Text:
- Date Issued: 2007
Neural network-based prediction techniques for global modeling of M(3000)F2 ionospheric parameter
- Oyeyemi, E O, McKinnell, Lee-Anne, Poole, Allon W V
- Authors: Oyeyemi, E O , McKinnell, Lee-Anne , Poole, Allon W V
- Date: 2007
- Language: English
- Type: text , Article
- Identifier: vital:6803 , http://hdl.handle.net/10962/d1004166
- Description: In recent times neural networks (NNs) have been employed to solve many problems in ionospheric predictions. This paper illustrates a new application of NNs in developing a global model of the ionospheric propagation factor M(3000)F2. NNs were trained with daily hourly values of M(3000)F2 from various ionospheric stations spanning the period 1964–1986 with the following temporal and spatial input parameters: Universal Time, geographic latitude, magnetic inclination, magnetic declination, solar zenith angle, day of the year, A16 index (a 2-day running mean of the 3-h planetary magnetic ap index), R2 index (a 2-month running mean of sunspot number), and the angle of meridian relative to the subsolar point. The performance of the NNs was verified by comparing the predicted values of M(3000)F2 with observed values from a few selected ionospheric stations and the IRI (International Reference Ionosphere) model (CCIR M(3000)F2 model) predicted values. The results obtained compared favourably with the IRI model. Based on the error differences, the result obtained justifies the potential of the NN technique for the predictions of M(3000)F2 values on a global scale.
- Full Text:
- Date Issued: 2007
- Authors: Oyeyemi, E O , McKinnell, Lee-Anne , Poole, Allon W V
- Date: 2007
- Language: English
- Type: text , Article
- Identifier: vital:6803 , http://hdl.handle.net/10962/d1004166
- Description: In recent times neural networks (NNs) have been employed to solve many problems in ionospheric predictions. This paper illustrates a new application of NNs in developing a global model of the ionospheric propagation factor M(3000)F2. NNs were trained with daily hourly values of M(3000)F2 from various ionospheric stations spanning the period 1964–1986 with the following temporal and spatial input parameters: Universal Time, geographic latitude, magnetic inclination, magnetic declination, solar zenith angle, day of the year, A16 index (a 2-day running mean of the 3-h planetary magnetic ap index), R2 index (a 2-month running mean of sunspot number), and the angle of meridian relative to the subsolar point. The performance of the NNs was verified by comparing the predicted values of M(3000)F2 with observed values from a few selected ionospheric stations and the IRI (International Reference Ionosphere) model (CCIR M(3000)F2 model) predicted values. The results obtained compared favourably with the IRI model. Based on the error differences, the result obtained justifies the potential of the NN technique for the predictions of M(3000)F2 values on a global scale.
- Full Text:
- Date Issued: 2007
Role playing African development : an international comparison
- Fox, Roddy C, Assmo, P, Kjellgren, H
- Authors: Fox, Roddy C , Assmo, P , Kjellgren, H
- Date: 2007
- Language: English
- Type: Conference paper
- Identifier: vital:6665 , http://hdl.handle.net/10962/d1006676
- Description: The African Development Game is a role playing simulation developed to demonstrate the difficulties six African countries face in reaching the Millennium Development Goals. The game has been played in three different countries, South Africa, Sweden and Finland, to examine its utility as a learning tool for students who are unfamiliar both with the Millennium Development Goals and the problems of African development. Analysis of the games played in South Africa and Sweden. is based on a comparison of student reflections supplemented by participant observation and spreadsheet information of economic performances. Marked differences in the types of learning and success in repaying debt were observed between the two groups of students. They all commented, however, on the effectiveness of the role play as a learning tool.
- Full Text:
- Date Issued: 2007
- Authors: Fox, Roddy C , Assmo, P , Kjellgren, H
- Date: 2007
- Language: English
- Type: Conference paper
- Identifier: vital:6665 , http://hdl.handle.net/10962/d1006676
- Description: The African Development Game is a role playing simulation developed to demonstrate the difficulties six African countries face in reaching the Millennium Development Goals. The game has been played in three different countries, South Africa, Sweden and Finland, to examine its utility as a learning tool for students who are unfamiliar both with the Millennium Development Goals and the problems of African development. Analysis of the games played in South Africa and Sweden. is based on a comparison of student reflections supplemented by participant observation and spreadsheet information of economic performances. Marked differences in the types of learning and success in repaying debt were observed between the two groups of students. They all commented, however, on the effectiveness of the role play as a learning tool.
- Full Text:
- Date Issued: 2007
Shopstewards summit - Notice and Agenda
- SACCAWU
- Authors: SACCAWU
- Date: Oct 2007
- Subjects: SACCAWU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/137723 , vital:37553
- Description: Comrades National Office Bearers of SACCAWU, other leadership of the Union at various level, the Wits Regional leadership of SACCAWU, the Shoprite Checkers NSSC NOBs, Officials, esteemed guests and delegates to this Summit, a substructure to the NSSC, I bring you warm and revolutionary greetings on behalf of the Shoprite Checkers NOBs and the entire NSSC and the entire SACCAWU membership. We are indeed honoured that you have all, particularly the SACCAWU NOBs, Officials and Guests, went to great length and sacrifices to ensure that you form part of this historic Summit. It is historic in that it is the only meeting of national competence convened in the year the NSSC turns twenty. Lest we forget, the Shoprite Council was launched in 1987, and has over the years relaunched to match the developments that were taking place within the company as it was growing its brands. Without your presence, we have no doubt that our debates would be poorer, leading to decisions that might in the long run prove inappropriate. You are once more welcome and assured that you are free to participate in the deliberations over the next few days. The Council have seen various onslaughts through the years and survived the iron-fisted resolve of the brutal apartheid regime and the capitalist system in its changing forms. It is the experiences of the time that has moulded numerous Shopstewards to an extent of understanding the necessity of participating within the Union and Federation structures. It is no coincidence that today, this Council has many of its Shopstewards in the CEC of the Union. It is of course worthless to have numbers in such structures if we do not play a positive and constructive role in shaping the direction of the Union. We can only do so if we are really grounded on the traditions of the mass democratic movement and the national democratic revolution.
- Full Text:
- Date Issued: Oct 2007
- Authors: SACCAWU
- Date: Oct 2007
- Subjects: SACCAWU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/137723 , vital:37553
- Description: Comrades National Office Bearers of SACCAWU, other leadership of the Union at various level, the Wits Regional leadership of SACCAWU, the Shoprite Checkers NSSC NOBs, Officials, esteemed guests and delegates to this Summit, a substructure to the NSSC, I bring you warm and revolutionary greetings on behalf of the Shoprite Checkers NOBs and the entire NSSC and the entire SACCAWU membership. We are indeed honoured that you have all, particularly the SACCAWU NOBs, Officials and Guests, went to great length and sacrifices to ensure that you form part of this historic Summit. It is historic in that it is the only meeting of national competence convened in the year the NSSC turns twenty. Lest we forget, the Shoprite Council was launched in 1987, and has over the years relaunched to match the developments that were taking place within the company as it was growing its brands. Without your presence, we have no doubt that our debates would be poorer, leading to decisions that might in the long run prove inappropriate. You are once more welcome and assured that you are free to participate in the deliberations over the next few days. The Council have seen various onslaughts through the years and survived the iron-fisted resolve of the brutal apartheid regime and the capitalist system in its changing forms. It is the experiences of the time that has moulded numerous Shopstewards to an extent of understanding the necessity of participating within the Union and Federation structures. It is no coincidence that today, this Council has many of its Shopstewards in the CEC of the Union. It is of course worthless to have numbers in such structures if we do not play a positive and constructive role in shaping the direction of the Union. We can only do so if we are really grounded on the traditions of the mass democratic movement and the national democratic revolution.
- Full Text:
- Date Issued: Oct 2007
South African marxist state theory: a critical overview
- Authors: Helliker, Kirk D
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144778 , vital:38378 , DOI: 10.1080/02589348808704885
- Description: The article provides a critical analysis of Marxist work on the South African state. It first examines the early Poulantzian‐State Derivationist debate on the relation between state and society, and then discusses the ‘new directions’ which focus on the state itself. The sensitivity of the ‘new directions’ to the traditional Weberian concern about state bureaucracy is important for enriching Marxist theory. But the article concludes by suggesting that a comprehensive dialectical Marxist approach to the South African state still awaits development.
- Full Text:
- Date Issued: 2007
- Authors: Helliker, Kirk D
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144778 , vital:38378 , DOI: 10.1080/02589348808704885
- Description: The article provides a critical analysis of Marxist work on the South African state. It first examines the early Poulantzian‐State Derivationist debate on the relation between state and society, and then discusses the ‘new directions’ which focus on the state itself. The sensitivity of the ‘new directions’ to the traditional Weberian concern about state bureaucracy is important for enriching Marxist theory. But the article concludes by suggesting that a comprehensive dialectical Marxist approach to the South African state still awaits development.
- Full Text:
- Date Issued: 2007
Written medicines information for South African HIV/AIDS patients: does it enhance understanding of co-trimoxazole therapy?
- Mansoor, Leila E, Dowse, Roslind
- Authors: Mansoor, Leila E , Dowse, Roslind
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156860 , vital:40059 , https://0-doi.org.wam.seals.ac.za/10.1093/her/cyl039
- Description: Written information to promote patient education is being increasingly recognized as an integral part of quality health care. The main objective of this study was to evaluate the effect of distributing a patient information leaflet (PIL) on knowledge acquisition and recall. Two different PILs were designed for co-trimoxazole tablets: a simple, shorter PIL that incorporated pictograms and text and a text-only PIL that was longer and more complex. Human immunodeficiency virus-positive participants on chronic co-trimoxazole therapy were enrolled from five local primary health care clinics in Grahamstown, South Africa, and were randomly allocated to a Control Group (no PIL), Group A (text-only PIL) or Group B (simple PIL with pictograms).
- Full Text:
- Date Issued: 2007
- Authors: Mansoor, Leila E , Dowse, Roslind
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156860 , vital:40059 , https://0-doi.org.wam.seals.ac.za/10.1093/her/cyl039
- Description: Written information to promote patient education is being increasingly recognized as an integral part of quality health care. The main objective of this study was to evaluate the effect of distributing a patient information leaflet (PIL) on knowledge acquisition and recall. Two different PILs were designed for co-trimoxazole tablets: a simple, shorter PIL that incorporated pictograms and text and a text-only PIL that was longer and more complex. Human immunodeficiency virus-positive participants on chronic co-trimoxazole therapy were enrolled from five local primary health care clinics in Grahamstown, South Africa, and were randomly allocated to a Control Group (no PIL), Group A (text-only PIL) or Group B (simple PIL with pictograms).
- Full Text:
- Date Issued: 2007
Development and validation of a stability-indicating analytical method for the quantitation of oxytocin in pharmaceutical dosage forms
- Chaibva, Faith A, Walker, Roderick B
- Authors: Chaibva, Faith A , Walker, Roderick B
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6349 , http://hdl.handle.net/10962/d1006030
- Description: A single stability-indicating assay for oxytocin (OT) in pharmaceutical dosage forms using gradient elution over 21 min has been reported in the literature. Furthermore, published and compendial methods for the analysis of OT containing dosage forms also involve using HPLC with gradient elution and complicated mobile phases that include hydrophobic ion pairing agents. A simple isocratic and stability-indicating assay was developed and validated. The conditions are as follows, column: Phenomenex® C18 Hypersil, 5 μm packing, 4.6 mm × 150 mm with acetonitrile–phosphate buffer (pH 5; 0.08 M) (20:80) as the mobile phase with UV detection at 220 nm The method was found to be specific for OT in the presence of degradation products and chlorbutol (preservative) with an overall analytical run time of 16 min. Accuracy was determined to be 0.77–1.18% bias for all samples tested. Intra-assay precision (repeatability) was found to be 0.22–1.04%R.S.D. while the inter-day precision (intermediate precision) was found to be 1.27–1.68%R.S.D. for the samples studied. The calibration curve was found to be linear with the equation y = 1.81x + 0.02 and a linear regression coefficient of 0.9991 over the range 0.4–12.0 IU/ml. The LOD and the LOQ were determined to be 0.1 and 0.4 IU/ml, respectively. Syntocinon®, a commercially available dosage form of OT was assayed resulting in 100.5–106.6% recovery of the label claim and an average of 10.04 IU/ml.
- Full Text:
- Date Issued: 2006
- Authors: Chaibva, Faith A , Walker, Roderick B
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6349 , http://hdl.handle.net/10962/d1006030
- Description: A single stability-indicating assay for oxytocin (OT) in pharmaceutical dosage forms using gradient elution over 21 min has been reported in the literature. Furthermore, published and compendial methods for the analysis of OT containing dosage forms also involve using HPLC with gradient elution and complicated mobile phases that include hydrophobic ion pairing agents. A simple isocratic and stability-indicating assay was developed and validated. The conditions are as follows, column: Phenomenex® C18 Hypersil, 5 μm packing, 4.6 mm × 150 mm with acetonitrile–phosphate buffer (pH 5; 0.08 M) (20:80) as the mobile phase with UV detection at 220 nm The method was found to be specific for OT in the presence of degradation products and chlorbutol (preservative) with an overall analytical run time of 16 min. Accuracy was determined to be 0.77–1.18% bias for all samples tested. Intra-assay precision (repeatability) was found to be 0.22–1.04%R.S.D. while the inter-day precision (intermediate precision) was found to be 1.27–1.68%R.S.D. for the samples studied. The calibration curve was found to be linear with the equation y = 1.81x + 0.02 and a linear regression coefficient of 0.9991 over the range 0.4–12.0 IU/ml. The LOD and the LOQ were determined to be 0.1 and 0.4 IU/ml, respectively. Syntocinon®, a commercially available dosage form of OT was assayed resulting in 100.5–106.6% recovery of the label claim and an average of 10.04 IU/ml.
- Full Text:
- Date Issued: 2006
Identifying and Investigating Intrusive Scanning Patterns by Visualizing Network Telescope Traffic in a 3-D Scatter-plot
- van Riel, Jean-Pierre, Irwin, Barry V W
- Authors: van Riel, Jean-Pierre , Irwin, Barry V W
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428719 , vital:72531 , https://citeseerx.ist.psu.edu/document?repid=rep1type=pdfanddoi=aeb0738f0e53a8c9f407fee7e55c852643f2644c
- Description: Detecting and investigating intrusive Internet activity is an ever-present challenge for network administrators and security researchers. Network monitoring can generate large, unmanageable amounts of log data, which further complicates distinguishing between illegitimate and legiti-mate traffic. Considering the above issue, this article has two aims. First, it describes an investigative methodology for network monitoring and traffic review; and second, it discusses results from applying this meth-od. The method entails a combination of network telescope traffic cap-ture and visualisation. Observing traffic from the perspective of a dedi-cated sensor network reduces the volume of data and alleviates the concern of confusing malicious traffic with legitimate traffic. Compliment-ing this, visual analysis facilitates the rapid review and correlation of events, thereby utilizing human intelligence in the identification of scan-ning patterns. To demonstrate the proposed method, several months of network telescope traffic is captured and analysed with a tailor made 3D scatter-plot visualisation. As the results show, the visualisation saliently conveys anomalous patterns, and further analysis reveals that these patterns are indicative of covert network probing activity. By incorporat-ing visual analysis with traditional approaches, such as textual log re-view and the use of an intrusion detection system, this research contrib-utes improved insight into network scanning incidents.
- Full Text:
- Date Issued: 2006
- Authors: van Riel, Jean-Pierre , Irwin, Barry V W
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428719 , vital:72531 , https://citeseerx.ist.psu.edu/document?repid=rep1type=pdfanddoi=aeb0738f0e53a8c9f407fee7e55c852643f2644c
- Description: Detecting and investigating intrusive Internet activity is an ever-present challenge for network administrators and security researchers. Network monitoring can generate large, unmanageable amounts of log data, which further complicates distinguishing between illegitimate and legiti-mate traffic. Considering the above issue, this article has two aims. First, it describes an investigative methodology for network monitoring and traffic review; and second, it discusses results from applying this meth-od. The method entails a combination of network telescope traffic cap-ture and visualisation. Observing traffic from the perspective of a dedi-cated sensor network reduces the volume of data and alleviates the concern of confusing malicious traffic with legitimate traffic. Compliment-ing this, visual analysis facilitates the rapid review and correlation of events, thereby utilizing human intelligence in the identification of scan-ning patterns. To demonstrate the proposed method, several months of network telescope traffic is captured and analysed with a tailor made 3D scatter-plot visualisation. As the results show, the visualisation saliently conveys anomalous patterns, and further analysis reveals that these patterns are indicative of covert network probing activity. By incorporat-ing visual analysis with traditional approaches, such as textual log re-view and the use of an intrusion detection system, this research contrib-utes improved insight into network scanning incidents.
- Full Text:
- Date Issued: 2006
Improving the bioremediation of phenolic wastewaters by Trametes versicolor
- Ryan, D, Leukes, W, Burton, Stephanie G
- Authors: Ryan, D , Leukes, W , Burton, Stephanie G
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6467 , http://hdl.handle.net/10962/d1005796 , http://dx.doi.org/10.1016/j.biortech.2006.02.001
- Description: The successful bioremediation of a phenolic wastewater by Trametes versicolor was found to be dependent on a range of factors including: fungal growth, culture age and activity and enzyme (laccase) production. These aspects were enhanced by the optimisation of the growth medium used and time of addition of the pollutant to the fungal cultures. Different media containing ‘high’ (20 g/L), ‘low’ (2 g/L) and ‘sufficient’ (10 g/L) concentrations of carbon and nitrogen sources were investigated. The medium containing both glucose and peptone at 10 g/L resulted in the highest Growth Related Productivity (the product of specific yield and μ) of laccase (1.46 Units of laccase activity)/gram biomass/day and was used in all further experiments. The use of the guaiacol as an inducer further increased laccase activity 780% without inhibiting growth; similarly the phenolic effluent studied boosted activity almost 5 times. The timing of the addition of the phenolic effluent was found to have important consequences in its removal and at least 8 days of prior growth was required. Under these conditions, 0.125 g phenol/g biomass and 0.231 g o-cresol/g biomass were removed from solution per day.
- Full Text:
- Date Issued: 2006
- Authors: Ryan, D , Leukes, W , Burton, Stephanie G
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6467 , http://hdl.handle.net/10962/d1005796 , http://dx.doi.org/10.1016/j.biortech.2006.02.001
- Description: The successful bioremediation of a phenolic wastewater by Trametes versicolor was found to be dependent on a range of factors including: fungal growth, culture age and activity and enzyme (laccase) production. These aspects were enhanced by the optimisation of the growth medium used and time of addition of the pollutant to the fungal cultures. Different media containing ‘high’ (20 g/L), ‘low’ (2 g/L) and ‘sufficient’ (10 g/L) concentrations of carbon and nitrogen sources were investigated. The medium containing both glucose and peptone at 10 g/L resulted in the highest Growth Related Productivity (the product of specific yield and μ) of laccase (1.46 Units of laccase activity)/gram biomass/day and was used in all further experiments. The use of the guaiacol as an inducer further increased laccase activity 780% without inhibiting growth; similarly the phenolic effluent studied boosted activity almost 5 times. The timing of the addition of the phenolic effluent was found to have important consequences in its removal and at least 8 days of prior growth was required. Under these conditions, 0.125 g phenol/g biomass and 0.231 g o-cresol/g biomass were removed from solution per day.
- Full Text:
- Date Issued: 2006
Integrating Secure RTP into the Open Source VoIP PBX Asterisk
- Clayton, Bradley, Irwin, Barry V W, Terzoli, Alfredo
- Authors: Clayton, Bradley , Irwin, Barry V W , Terzoli, Alfredo
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428735 , vital:72532 , https://d1wqtxts1xzle7.cloudfront.net/84872934/66_Paper-libre.pdf?1650920302=response-content-disposi-tion=inline%3B+filename%3DIntegrating_Secure_RTP_into_the_Open_Sou.pdfExpires=1714744382Signature=PijjCGW0qcvkqRe-2R55HocKLvz9Ljw8jmhQvRQEi9YqJl7eWSiYnvs9CogY4u4bmDTYTLpvkA-nlfbiszg-s7Cq2nbLn3PUdfJ5cA11ujboi~i7oSoem7smuN1YCVZlg7FnZRd6mOXdTry9UAh8TlWyndF6pY1RXtc7bgb5cWeK4ggJ7~bM0HUXEbUKKa-abCZnGNrAZ59JIdL6CNx1Sht3o5mZTcyRL3PNVSOz17lldXi4FsAOEUwsVV-uv04hzp6pe6Qv5WbAP6tqk7deyoLUwk58A9F-PaJlOLy2gDAVLnbKT8RrxYg8tqv8SuBhPWb32CefBxv486N3F6izZw__Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA
- Description: Implementations of Voice over Internet Protocol (VoIP) have focused, up to now, mainly on the need to transport data in real-time, often at the expense of security. The neglect of secure VoIP is often intentional, as developers are striving to minimise overheads and delays. The Secure Real-Time Protocol (SRTP) has the potential to secure real-time streams without exacting too high a performance price. SRTP is the addition of security to the audio/video profile used in the Real-Time Transport Protocol (RTP). SRTP adds confidentiality, integrity and op-tionaly authenticity to RTP media streams. This paper focuses on the integration of SRTP into Asterisk, an open-source VoIP PBX. SRTP support has recently been added to Asterisk by Mikael Magnusson. This paper analyses Magnusson’s implementation, contrasting it to a proof-of-concept implementation developed independently at Rhodes University. The interoperability of SRTP implementations cannot be taken for granted, given the relatively recent standardization of the pro-tocol, and so Magnusson’s implementation is tested against another SRTP implementation. Finally, the paper highlights a major shortcoming in Magnusson’s implementation, namely that the exchange of encryp-tion keys is done in the clear. It concludes by proposing possible solu-tions, such as TLS, IPSec and MIkey.
- Full Text:
- Date Issued: 2006
- Authors: Clayton, Bradley , Irwin, Barry V W , Terzoli, Alfredo
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428735 , vital:72532 , https://d1wqtxts1xzle7.cloudfront.net/84872934/66_Paper-libre.pdf?1650920302=response-content-disposi-tion=inline%3B+filename%3DIntegrating_Secure_RTP_into_the_Open_Sou.pdfExpires=1714744382Signature=PijjCGW0qcvkqRe-2R55HocKLvz9Ljw8jmhQvRQEi9YqJl7eWSiYnvs9CogY4u4bmDTYTLpvkA-nlfbiszg-s7Cq2nbLn3PUdfJ5cA11ujboi~i7oSoem7smuN1YCVZlg7FnZRd6mOXdTry9UAh8TlWyndF6pY1RXtc7bgb5cWeK4ggJ7~bM0HUXEbUKKa-abCZnGNrAZ59JIdL6CNx1Sht3o5mZTcyRL3PNVSOz17lldXi4FsAOEUwsVV-uv04hzp6pe6Qv5WbAP6tqk7deyoLUwk58A9F-PaJlOLy2gDAVLnbKT8RrxYg8tqv8SuBhPWb32CefBxv486N3F6izZw__Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA
- Description: Implementations of Voice over Internet Protocol (VoIP) have focused, up to now, mainly on the need to transport data in real-time, often at the expense of security. The neglect of secure VoIP is often intentional, as developers are striving to minimise overheads and delays. The Secure Real-Time Protocol (SRTP) has the potential to secure real-time streams without exacting too high a performance price. SRTP is the addition of security to the audio/video profile used in the Real-Time Transport Protocol (RTP). SRTP adds confidentiality, integrity and op-tionaly authenticity to RTP media streams. This paper focuses on the integration of SRTP into Asterisk, an open-source VoIP PBX. SRTP support has recently been added to Asterisk by Mikael Magnusson. This paper analyses Magnusson’s implementation, contrasting it to a proof-of-concept implementation developed independently at Rhodes University. The interoperability of SRTP implementations cannot be taken for granted, given the relatively recent standardization of the pro-tocol, and so Magnusson’s implementation is tested against another SRTP implementation. Finally, the paper highlights a major shortcoming in Magnusson’s implementation, namely that the exchange of encryp-tion keys is done in the clear. It concludes by proposing possible solu-tions, such as TLS, IPSec and MIkey.
- Full Text:
- Date Issued: 2006
Medicines information and adherence in HIV/AIDS patients
- Mansoor, Leila E, Dowse, Roslind
- Authors: Mansoor, Leila E , Dowse, Roslind
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6395 , http://hdl.handle.net/10962/d1006319
- Description: Background: Providing written medicines information is being legislated in an increasing number of countries worldwide, with the patient information leaflet (PIL) being the most widely used method for conveying health information. The impact of providing such information on adherence to therapy is reportedly unpredictable. Therapy for human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) and related opportunistic infections usually involves polytherapy and complex regimens, both of which are risk factors for non-adherence. The objective of this study was to assess the impact of medicines information on adherence to chronic co-trimoxazole therapy in low-literate HIV/AIDS patients. Methods: Two different PILs were designed for co-trimoxazole tablets and were available in both English and isiXhosa. Participants were randomly allocated to a control group (receiving no PIL), group A (receiving a 'complex PIL') and group B (receiving a 'simple PIL' incorporating pictograms). At the first interview, demographic data were collected and the time, date and day that the participant would take his/her first tablet of the month's course was also documented. In a follow-up interview adherence to therapy was assessed using two methods; self-report and tablet count. Results: The medicines information materials incorporating simple text and pictograms resulted in significantly improved adherence to therapy in the short term, whereas a non-significant increase in adherence was associated with the availability of the more complex information. This was shown by both the self-reported assessment as well as the tablet count. Conclusion: This research suggests that appropriately designed written material can have a positive impact in improving adherence and, together with verbal consultation, are essential for enabling patients to make appropriate decisions about their medicine taking.
- Full Text:
- Date Issued: 2006
- Authors: Mansoor, Leila E , Dowse, Roslind
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6395 , http://hdl.handle.net/10962/d1006319
- Description: Background: Providing written medicines information is being legislated in an increasing number of countries worldwide, with the patient information leaflet (PIL) being the most widely used method for conveying health information. The impact of providing such information on adherence to therapy is reportedly unpredictable. Therapy for human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) and related opportunistic infections usually involves polytherapy and complex regimens, both of which are risk factors for non-adherence. The objective of this study was to assess the impact of medicines information on adherence to chronic co-trimoxazole therapy in low-literate HIV/AIDS patients. Methods: Two different PILs were designed for co-trimoxazole tablets and were available in both English and isiXhosa. Participants were randomly allocated to a control group (receiving no PIL), group A (receiving a 'complex PIL') and group B (receiving a 'simple PIL' incorporating pictograms). At the first interview, demographic data were collected and the time, date and day that the participant would take his/her first tablet of the month's course was also documented. In a follow-up interview adherence to therapy was assessed using two methods; self-report and tablet count. Results: The medicines information materials incorporating simple text and pictograms resulted in significantly improved adherence to therapy in the short term, whereas a non-significant increase in adherence was associated with the availability of the more complex information. This was shown by both the self-reported assessment as well as the tablet count. Conclusion: This research suggests that appropriately designed written material can have a positive impact in improving adherence and, together with verbal consultation, are essential for enabling patients to make appropriate decisions about their medicine taking.
- Full Text:
- Date Issued: 2006
The Need for Centralised, Cross Platform Information Aggregation
- Otten, Fred, Irwin, Barry V W, Slay, Hannah
- Authors: Otten, Fred , Irwin, Barry V W , Slay, Hannah
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428773 , vital:72535 , https://d1wqtxts1xzle7.cloudfront.net/2355475/8jlt6v8tz4wmhs6.pdf?1425084143=response-content-disposi-tion=inline%3B+filename%3DThe_need_for_centralised_cross_platform.pdfExpires=1714743760Signature=fsImuFaOfYc2FtUC88DqRrK1Anh84~rvBsZt2j46BfPyKMbbmswGZN5E2ajRJ7tZi5SZ4zQJvI5U6L47nmoXlNA0~Vo3pON-sYEo6Kn3TiTLvxwUpPQALnP7IvL-EEhgh11T-OuNZf0Q8QArxk6iqi4zjiOYbHUb~FDWw8MJ7ekH~frNS75mDrjpZ4xL8MqPNRHctaR3E5m~4i71SYO8hfbZw4vu7AhNNNvrRoIhbtLCEUsg-j7TkBDgVHts8LCsM5knmEKwgQTSBQTkLoRuNmXngqYikjvL7jUuHXibjSVaMSD78WRqXE~LDDkT7KXU7EbkPXzjRYJyamQ5qDXa3A__ey-Pair-Id=APKAJLOHF5GGSLRBV4ZA
- Description: With the move towards global and multi-national companies, information technology infrastructure requirements are increasing. As the size of these computer networks increases, it becomes more and more difficult to moni-tor, control, and secure them. Network security involves the creation of large amounts of information in the form of logs and messages from a number of diverse devices, sensors, and gateways which are often spread over large geographical areas. This makes the monitoring and control difficult, and hence poses security problems. The aggregation of information is necessary in information audits, intrusion detection, network monitoring and management. The use of different platforms and devices complicates the problem, and makes aggregation more difficult. Network security administrators and security researchers require aggregation to simplify the analysis and comprehension of activity across the entire net-work. Centralised information aggregation will help deal with redundancy, analysis, monitoring and control. This aids the detection of wide spread attacks on global organisational networks, improving intrusion detection and mitigation. This paper discusses and motivates the need for central-ised, cross platform information aggregation in greater detail. It also sug-gests methods which may be used, discusses the security issues, and gives the advantages and disadvantages of aggregation.
- Full Text:
- Date Issued: 2006
- Authors: Otten, Fred , Irwin, Barry V W , Slay, Hannah
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428773 , vital:72535 , https://d1wqtxts1xzle7.cloudfront.net/2355475/8jlt6v8tz4wmhs6.pdf?1425084143=response-content-disposi-tion=inline%3B+filename%3DThe_need_for_centralised_cross_platform.pdfExpires=1714743760Signature=fsImuFaOfYc2FtUC88DqRrK1Anh84~rvBsZt2j46BfPyKMbbmswGZN5E2ajRJ7tZi5SZ4zQJvI5U6L47nmoXlNA0~Vo3pON-sYEo6Kn3TiTLvxwUpPQALnP7IvL-EEhgh11T-OuNZf0Q8QArxk6iqi4zjiOYbHUb~FDWw8MJ7ekH~frNS75mDrjpZ4xL8MqPNRHctaR3E5m~4i71SYO8hfbZw4vu7AhNNNvrRoIhbtLCEUsg-j7TkBDgVHts8LCsM5knmEKwgQTSBQTkLoRuNmXngqYikjvL7jUuHXibjSVaMSD78WRqXE~LDDkT7KXU7EbkPXzjRYJyamQ5qDXa3A__ey-Pair-Id=APKAJLOHF5GGSLRBV4ZA
- Description: With the move towards global and multi-national companies, information technology infrastructure requirements are increasing. As the size of these computer networks increases, it becomes more and more difficult to moni-tor, control, and secure them. Network security involves the creation of large amounts of information in the form of logs and messages from a number of diverse devices, sensors, and gateways which are often spread over large geographical areas. This makes the monitoring and control difficult, and hence poses security problems. The aggregation of information is necessary in information audits, intrusion detection, network monitoring and management. The use of different platforms and devices complicates the problem, and makes aggregation more difficult. Network security administrators and security researchers require aggregation to simplify the analysis and comprehension of activity across the entire net-work. Centralised information aggregation will help deal with redundancy, analysis, monitoring and control. This aids the detection of wide spread attacks on global organisational networks, improving intrusion detection and mitigation. This paper discusses and motivates the need for central-ised, cross platform information aggregation in greater detail. It also sug-gests methods which may be used, discusses the security issues, and gives the advantages and disadvantages of aggregation.
- Full Text:
- Date Issued: 2006
Towards Central Vulnerability Management By Mobile Phone Operators
- Moyo, Thamsanqa, Irwin, Barry V W, Wright, Madeleineh
- Authors: Moyo, Thamsanqa , Irwin, Barry V W , Wright, Madeleineh
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428787 , vital:72536 , https://www.researchgate.net/profile/Barry-Ir-win/publication/237107512_Securing_mobile_commerce_interactions_through_secure_mobile_web_services/links/5b9a5898a6fdccd3cb4ff6cf/Securing-mobile-commerce-interactions-through-secure-mobile-web-services.pdf
- Description: The application of XML-based approaches in passing vulnerability in-formation between vulnerability management devices or software resid-ing on wired networks has been demonstrated. We propose a proof of concept framework for mobile operators that extends this use of XML into the area of vulnerability management on public land mobile net-works. Our proposed framework allows for a pro-active central man-agement of vulnerabilities found on mobile stations such as mobile phones. Despite the relatively limited number of reported vulnerabilities on mobile stations, such a pre-emptive approach from mobile operators is necessary to acquire the confidence of early adopters in Mobile Commerce. Given the diverse collection of devices and software that exist on a public land mobile network, XML-based approaches are best able to providing the inter-operability required for vulnerability manage-ment on such a network. Our proposed framework leverages web ser-vices by using the Open Vulnerability Assessment Language (OVAL) to provide vulnerability descriptions, and by securing these descriptions in SOAP messages conforming to the OASIS Web Services Security (WSS) standard. We contribute in three areas: firstly, through this framework we show that mobile operators can carry out centralized vul-nerability management on their public land mobile networks comprising of a wide variety of devices and software. Secondly, the assurance of integrity, confidentiality and non-repudiation inherently lacking in OVAL vulnerability descriptions is achieved through their encapsulation in SOAP messages conforming to the OASIS WSS standard. Thirdly, SOAP-based web service implementations allow for integration with vulnerability management tools and devices that do not conform to OVAL.
- Full Text:
- Date Issued: 2006
- Authors: Moyo, Thamsanqa , Irwin, Barry V W , Wright, Madeleineh
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428787 , vital:72536 , https://www.researchgate.net/profile/Barry-Ir-win/publication/237107512_Securing_mobile_commerce_interactions_through_secure_mobile_web_services/links/5b9a5898a6fdccd3cb4ff6cf/Securing-mobile-commerce-interactions-through-secure-mobile-web-services.pdf
- Description: The application of XML-based approaches in passing vulnerability in-formation between vulnerability management devices or software resid-ing on wired networks has been demonstrated. We propose a proof of concept framework for mobile operators that extends this use of XML into the area of vulnerability management on public land mobile net-works. Our proposed framework allows for a pro-active central man-agement of vulnerabilities found on mobile stations such as mobile phones. Despite the relatively limited number of reported vulnerabilities on mobile stations, such a pre-emptive approach from mobile operators is necessary to acquire the confidence of early adopters in Mobile Commerce. Given the diverse collection of devices and software that exist on a public land mobile network, XML-based approaches are best able to providing the inter-operability required for vulnerability manage-ment on such a network. Our proposed framework leverages web ser-vices by using the Open Vulnerability Assessment Language (OVAL) to provide vulnerability descriptions, and by securing these descriptions in SOAP messages conforming to the OASIS Web Services Security (WSS) standard. We contribute in three areas: firstly, through this framework we show that mobile operators can carry out centralized vul-nerability management on their public land mobile networks comprising of a wide variety of devices and software. Secondly, the assurance of integrity, confidentiality and non-repudiation inherently lacking in OVAL vulnerability descriptions is achieved through their encapsulation in SOAP messages conforming to the OASIS WSS standard. Thirdly, SOAP-based web service implementations allow for integration with vulnerability management tools and devices that do not conform to OVAL.
- Full Text:
- Date Issued: 2006
A decision-making framework for restoring riparian zones degraded by invasive alien plants in South Africa
- Holmes, P M, Richardson, D M, Esler, K J, Witkowski, Ed T F, Fourie, S
- Authors: Holmes, P M , Richardson, D M , Esler, K J , Witkowski, Ed T F , Fourie, S
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6635 , http://hdl.handle.net/10962/d1006859
- Description: Riparian habitats in many parts of South Africa are severely degraded by invasive alien plants, especially trees. These invasions reduce water yields from catchments and affect riverine functioning and biodiversity. Initiatives are under way countrywide to clear alien plants from watercourses and surrounding catchments. Current understanding of key processes that regulate riparian functioning and define options for restoration is rudimentary. We review the impacts of riparian invasions and identify factors limiting the recovery of natural vegetation following alien clearance. We propose a framework of strategic interventions for optimizing restoration success. The framework identifies abiotic and biotic barriers to restoration at the scales of catchments and local reaches. In highly transformed catchments, interventions at the reach scale may fail if important barriers at the catchment scale are not addressed. The extent to which propagule supply and microsite conditions inhibit vegetation recovery is unknown. We also know little of the relative importance of dispersing vegetative propagules, dispersing seeds and soil-stored seed banks in vegetation dynamics, particularly after severe disturbances such as dense invasion by alien plants. The importance of geomorphological and hydrological factors in mediating recovery of riparian vegetation has not been adequately explored for all climatic areas in South Africa. More research is needed to determine the influence of different alien species and clearing treatments on the recovery of riparian vegetation. The literature strongly suggests that in highly alien-transformed catchments, the re-introduction of riparian species is required to promote recovery and suppress re-invasion. However, such interventions are unlikely to be widely implemented unless the cost: benefit ratios are favourable.
- Full Text:
- Date Issued: 2005
- Authors: Holmes, P M , Richardson, D M , Esler, K J , Witkowski, Ed T F , Fourie, S
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6635 , http://hdl.handle.net/10962/d1006859
- Description: Riparian habitats in many parts of South Africa are severely degraded by invasive alien plants, especially trees. These invasions reduce water yields from catchments and affect riverine functioning and biodiversity. Initiatives are under way countrywide to clear alien plants from watercourses and surrounding catchments. Current understanding of key processes that regulate riparian functioning and define options for restoration is rudimentary. We review the impacts of riparian invasions and identify factors limiting the recovery of natural vegetation following alien clearance. We propose a framework of strategic interventions for optimizing restoration success. The framework identifies abiotic and biotic barriers to restoration at the scales of catchments and local reaches. In highly transformed catchments, interventions at the reach scale may fail if important barriers at the catchment scale are not addressed. The extent to which propagule supply and microsite conditions inhibit vegetation recovery is unknown. We also know little of the relative importance of dispersing vegetative propagules, dispersing seeds and soil-stored seed banks in vegetation dynamics, particularly after severe disturbances such as dense invasion by alien plants. The importance of geomorphological and hydrological factors in mediating recovery of riparian vegetation has not been adequately explored for all climatic areas in South Africa. More research is needed to determine the influence of different alien species and clearing treatments on the recovery of riparian vegetation. The literature strongly suggests that in highly alien-transformed catchments, the re-introduction of riparian species is required to promote recovery and suppress re-invasion. However, such interventions are unlikely to be widely implemented unless the cost: benefit ratios are favourable.
- Full Text:
- Date Issued: 2005
A re-evaluation of plastochron index determination in peas - a case for using leaflet length
- Ade-Ademilua, Omobolanle Elizabeth, Botha, Christiaan E J
- Authors: Ade-Ademilua, Omobolanle Elizabeth , Botha, Christiaan E J
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6491 , http://hdl.handle.net/10962/d1004472
- Description: The plastochron index (PI) is a measure of plant growth reports our findings on PI using the average length of and can be used to determine growth rate, based upon the first pair of leaflets on each node. Early leaflet appearance of successive leaves on the axis of the growth in peas occurs exponentially and the early plant. PI should under ideal growth conditions be a stages of growth of successive pairs of leaflets occur at regular event and should be predictable with a relatively the same relative growth rate. Given that growth of small error of a few hours. PI has been variously leaflets during early development can be measured calculated in peas, and each method reported has had successfully, we propose the use of leaflet growth as a with it a number of problems that do not allow for measure of the plastochron index in peas. Our results reasonable prediction of PI. Internode length varies suggest that plant age is best expressed using the greatly and is dependent upon the variety, which may be plastochron index, which is a measure of the time short- or long-stemmed; thus this parameter is not ideal interval between the initiations of successive events — for determining growth rate or plant age. This paper in the case of peas, of successive pairs of leaflets.
- Full Text:
- Date Issued: 2005
- Authors: Ade-Ademilua, Omobolanle Elizabeth , Botha, Christiaan E J
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6491 , http://hdl.handle.net/10962/d1004472
- Description: The plastochron index (PI) is a measure of plant growth reports our findings on PI using the average length of and can be used to determine growth rate, based upon the first pair of leaflets on each node. Early leaflet appearance of successive leaves on the axis of the growth in peas occurs exponentially and the early plant. PI should under ideal growth conditions be a stages of growth of successive pairs of leaflets occur at regular event and should be predictable with a relatively the same relative growth rate. Given that growth of small error of a few hours. PI has been variously leaflets during early development can be measured calculated in peas, and each method reported has had successfully, we propose the use of leaflet growth as a with it a number of problems that do not allow for measure of the plastochron index in peas. Our results reasonable prediction of PI. Internode length varies suggest that plant age is best expressed using the greatly and is dependent upon the variety, which may be plastochron index, which is a measure of the time short- or long-stemmed; thus this parameter is not ideal interval between the initiations of successive events — for determining growth rate or plant age. This paper in the case of peas, of successive pairs of leaflets.
- Full Text:
- Date Issued: 2005
Abundance and commercialization of Phoenix Reclinata in the King Williamstown area, South Africa
- Gyan, C A, Shackleton, Charlie M
- Authors: Gyan, C A , Shackleton, Charlie M
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6634 , http://hdl.handle.net/10962/d1006829
- Description: In the Eastern Cape of South Africa the fronds of the wild palm Phoenix reclinata are harvested by rural women and manufactured into hand brushes, which are sold in urban centres. This paper reports on the abundance of P. reclinata palms, the profile of the harvesters, and the economic returns from trading in palm brushes as a case study of locally driven non-timber forest product commercialization. The palm resource was in a reasonable state with most clumps being lightly (36%) or moderately (43%) harvested, with many others uncut due to physical or culturally defined refugia. Tall trees within a clump were uncut because the fronds were too high. The estimated production of fronds was less than 25 per cent of the local demand. Consequently, harvesters were seeking alternative areas and species. Mean gross monthly income was R475 (USD45) which was an important cash contribution. Net income was 75 per cent of this. Income earned per seller was influenced by factors such as age, education, hours in the trade, and whether any household member received an old-age pension from the State. Older and less educated sellers had been trading longer than younger or more educated vendors.
- Full Text:
- Date Issued: 2005
- Authors: Gyan, C A , Shackleton, Charlie M
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6634 , http://hdl.handle.net/10962/d1006829
- Description: In the Eastern Cape of South Africa the fronds of the wild palm Phoenix reclinata are harvested by rural women and manufactured into hand brushes, which are sold in urban centres. This paper reports on the abundance of P. reclinata palms, the profile of the harvesters, and the economic returns from trading in palm brushes as a case study of locally driven non-timber forest product commercialization. The palm resource was in a reasonable state with most clumps being lightly (36%) or moderately (43%) harvested, with many others uncut due to physical or culturally defined refugia. Tall trees within a clump were uncut because the fronds were too high. The estimated production of fronds was less than 25 per cent of the local demand. Consequently, harvesters were seeking alternative areas and species. Mean gross monthly income was R475 (USD45) which was an important cash contribution. Net income was 75 per cent of this. Income earned per seller was influenced by factors such as age, education, hours in the trade, and whether any household member received an old-age pension from the State. Older and less educated sellers had been trading longer than younger or more educated vendors.
- Full Text:
- Date Issued: 2005