Volhoubaarheid van die kommersiële benutting van inheemse dekriet (Thamnochortus insignis) in die Suid-Kaap
- Authors: Horn, Johan Andries Muller
- Date: 2006
- Subjects: Fynbos -- Harvesting -- South Africa , Thatched roofs -- South Africa
- Language: Afrikaans
- Type: Thesis , Masters , MTech
- Identifier: vital:10591 , http://hdl.handle.net/10948/836 , http://hdl.handle.net/10948/d1012882 , Fynbos -- Harvesting -- South Africa , Thatched roofs -- South Africa
- Description: Thamnochortus insignis (Albertinia thatching reed) is a restio specie which is endemic in the narrow (20 km wide) coastal dune veld, from the Gouritz River in the east to the Breede River in the west (120 km). The area within this belt, where this reed is the dominant restio, covers 65 500 hectares. The culms of the reed is harvested as a natural product from the veld and used as thatch on roofs of houses. The traditional use has been as roofing material in Cape Dutch architecture. At this time, thatch roofs are regarded as a luxury commodity and are used in prestigious residential areas and also eco-friendly housing developments. The first section of the research project was based on a Delphi technique questionnaire completed first by 37 and secondly by 10 stakeholders in the industry. This group of growers, contract harvesters, crop agents and thatchers represented 80 percent percent of the estimated 2005 harvest and 87 percent of the estimated farm gate crop value. The thatching reed industry is the main agricultural enterprise situated in the coastal dune veld of the Southern Cape, i.e. 55 percent of total Gross Product Value generated by the survey respondents. The second section is based on an analysis of experimental harvest plots (50 m2), selected at random (4 replications per site) in the 2 x 3 different production systems, i.e. traditional harvest from natural veld, harvest from veld which had been subjected to mechanical injury ("sleep") and harvest from established orchard-type lands. Harvest data was collected at each site in terms of the following components, i.e. number of harvestable tussocks, circumference of tussocks and number of reed bundles (minimum circumference 210 mm, minimum length 1,2 m). The gross income per site was calculated on the basis of R1,80 per bundle (2006-price level). Economic analysis (Gross Margin above selected costs) indicates that plant density (reed tussocks/ha) is a critical factor, in order to offset the establishment cost of R2 100/ha in established lands, which is not incurred in the other two production systems. Economic returns from the first planted lands (2 100 and 2 900 plants/ha) averaged R7 666/ha against R8 781/ha for the mechanical-injury plants. However, at a density of 5 000 plants/ha, the projected Gross Margin increases to R15 765/ha. The use of mechanicalinjury and natural vegetation production systems both interfere with biodiversity and raise major concerns with regard to sustainability of the sensitive coastal dune fynbos. ANOVA-analysis of the data indicates a highly significant difference (p = 0,01) for all sites and production systems. Statistical analysis of averages indicates that mechanical injury treatment results in a significant increase in the number of tussocks, when compared to established and natural veld, respectively. The variance in the circumference of tussocks was greatest in natural veld (55 to 71 percent) and mechanical injury (54 to 61 percent). Tussocks harvested from established plantings reflected the least level of variance (28 to 38 percent). The larger reed tussocks in the established lands produced more bundles of marketable reed (8 200/ha) than the mechanical-injury (7 625/ha) and natural veld (3 450/ha) respectively. Establishment of T. insignis plantlets in an "orchard" system at spacings of 2 m x 1 m on previous winter cereal lands or old pastures, is shown to meet all the requirements within a sustainable production system, i.e. viability, productivity, environmental-friendly, risk management and social acceptance. Furthermore, the quality of the yield was in line with the proposed grading standard for thatching reed, i.e. minimum circumference 210 mm, minimum length 1,2 m and less than 6,5 percent grey culm content.
- Full Text:
- Date Issued: 2006
- Authors: Horn, Johan Andries Muller
- Date: 2006
- Subjects: Fynbos -- Harvesting -- South Africa , Thatched roofs -- South Africa
- Language: Afrikaans
- Type: Thesis , Masters , MTech
- Identifier: vital:10591 , http://hdl.handle.net/10948/836 , http://hdl.handle.net/10948/d1012882 , Fynbos -- Harvesting -- South Africa , Thatched roofs -- South Africa
- Description: Thamnochortus insignis (Albertinia thatching reed) is a restio specie which is endemic in the narrow (20 km wide) coastal dune veld, from the Gouritz River in the east to the Breede River in the west (120 km). The area within this belt, where this reed is the dominant restio, covers 65 500 hectares. The culms of the reed is harvested as a natural product from the veld and used as thatch on roofs of houses. The traditional use has been as roofing material in Cape Dutch architecture. At this time, thatch roofs are regarded as a luxury commodity and are used in prestigious residential areas and also eco-friendly housing developments. The first section of the research project was based on a Delphi technique questionnaire completed first by 37 and secondly by 10 stakeholders in the industry. This group of growers, contract harvesters, crop agents and thatchers represented 80 percent percent of the estimated 2005 harvest and 87 percent of the estimated farm gate crop value. The thatching reed industry is the main agricultural enterprise situated in the coastal dune veld of the Southern Cape, i.e. 55 percent of total Gross Product Value generated by the survey respondents. The second section is based on an analysis of experimental harvest plots (50 m2), selected at random (4 replications per site) in the 2 x 3 different production systems, i.e. traditional harvest from natural veld, harvest from veld which had been subjected to mechanical injury ("sleep") and harvest from established orchard-type lands. Harvest data was collected at each site in terms of the following components, i.e. number of harvestable tussocks, circumference of tussocks and number of reed bundles (minimum circumference 210 mm, minimum length 1,2 m). The gross income per site was calculated on the basis of R1,80 per bundle (2006-price level). Economic analysis (Gross Margin above selected costs) indicates that plant density (reed tussocks/ha) is a critical factor, in order to offset the establishment cost of R2 100/ha in established lands, which is not incurred in the other two production systems. Economic returns from the first planted lands (2 100 and 2 900 plants/ha) averaged R7 666/ha against R8 781/ha for the mechanical-injury plants. However, at a density of 5 000 plants/ha, the projected Gross Margin increases to R15 765/ha. The use of mechanicalinjury and natural vegetation production systems both interfere with biodiversity and raise major concerns with regard to sustainability of the sensitive coastal dune fynbos. ANOVA-analysis of the data indicates a highly significant difference (p = 0,01) for all sites and production systems. Statistical analysis of averages indicates that mechanical injury treatment results in a significant increase in the number of tussocks, when compared to established and natural veld, respectively. The variance in the circumference of tussocks was greatest in natural veld (55 to 71 percent) and mechanical injury (54 to 61 percent). Tussocks harvested from established plantings reflected the least level of variance (28 to 38 percent). The larger reed tussocks in the established lands produced more bundles of marketable reed (8 200/ha) than the mechanical-injury (7 625/ha) and natural veld (3 450/ha) respectively. Establishment of T. insignis plantlets in an "orchard" system at spacings of 2 m x 1 m on previous winter cereal lands or old pastures, is shown to meet all the requirements within a sustainable production system, i.e. viability, productivity, environmental-friendly, risk management and social acceptance. Furthermore, the quality of the yield was in line with the proposed grading standard for thatching reed, i.e. minimum circumference 210 mm, minimum length 1,2 m and less than 6,5 percent grey culm content.
- Full Text:
- Date Issued: 2006
Voltammetric analysis of pesticides and their degradation: A case study of Amitraz and its degradants
- Authors: Brimecombe, Rory Dennis
- Date: 2006
- Subjects: Hydrolysis , Biodegradation , Voltammetry , Pesticides -- Biodegradation , Pesticides -- Environmental aspects , Acaricides , Acaricides -- Physiological effect
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4131 , http://hdl.handle.net/10962/d1015724
- Description: Amitraz is a formamide acaricide used predominantly in the control of ectoparasites in livestock and honeybees. Amitraz hydrolysis is rapid and occurs under acidic conditions, exposure to sunlight and biodegradation by microorganisms. The main hydrolysis product of amitraz, 2,4-dimethylaniline, is recalcitrant in the environment and toxic to humans. An electrochemical method for the determination of total amitraz residues and its final breakdown product, 2,4-dimethylaniline, in spent cattle dip, is presented. Cyclic voltammetry at a glassy carbon electrode showed the irreversible oxidation of amitraz and 2,4-dimethylaniline. A limit of detection in the range of 8.5 x 10⁻⁸ M for amitraz and 2 x 10⁻⁸ M for 2,4-dimethylaniline was determined using differential pulse voltammetry. Feasibility studies in which the effect of supporting electrolyte type and pH had on electroanalysis of amitraz and its degradants, showed that pH affects current response as well as the potential at which amitraz and its degradants are oxidised. Britton-Robinson buffer was found to be the most suitable supporting electrolyte for detection of amitraz and its degradants in terms of sensitivity and reproducibility. Studies performed using environmental samples showed that the sensitivity and reproducibility of amitraz and 2,4-dimethylaniline analyses in spent cattle dip were comparable to analyses of amitraz and 2,4-dimethylaniline performed in Britton-Robinson buffer. In addition, the feasibility qf measuring amitraz and 2,4-dimethylaniline in environmental samples was assessed and compared to amitraz and 2,4-dimethylaniline analyses in Britton-Robinson buffer. Amitraz and 2,4-dimethylaniline were readily detectable in milk and honey. Furthermore, it was elucidated that 2,4-dimethylaniline can be metabolised to 3-methylcatechol by Pseudomonas species and the proposed breakdown pathway is presented. The biological degradation of amitraz and subsequent formation of 2,4-dimethylaniline was readily monitored in spent cattle dip. The breakdown of amitraz to 2,4-dimethylaniline and then to 3-MC was monitored using cyclic voltammetry.
- Full Text:
- Date Issued: 2006
- Authors: Brimecombe, Rory Dennis
- Date: 2006
- Subjects: Hydrolysis , Biodegradation , Voltammetry , Pesticides -- Biodegradation , Pesticides -- Environmental aspects , Acaricides , Acaricides -- Physiological effect
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4131 , http://hdl.handle.net/10962/d1015724
- Description: Amitraz is a formamide acaricide used predominantly in the control of ectoparasites in livestock and honeybees. Amitraz hydrolysis is rapid and occurs under acidic conditions, exposure to sunlight and biodegradation by microorganisms. The main hydrolysis product of amitraz, 2,4-dimethylaniline, is recalcitrant in the environment and toxic to humans. An electrochemical method for the determination of total amitraz residues and its final breakdown product, 2,4-dimethylaniline, in spent cattle dip, is presented. Cyclic voltammetry at a glassy carbon electrode showed the irreversible oxidation of amitraz and 2,4-dimethylaniline. A limit of detection in the range of 8.5 x 10⁻⁸ M for amitraz and 2 x 10⁻⁸ M for 2,4-dimethylaniline was determined using differential pulse voltammetry. Feasibility studies in which the effect of supporting electrolyte type and pH had on electroanalysis of amitraz and its degradants, showed that pH affects current response as well as the potential at which amitraz and its degradants are oxidised. Britton-Robinson buffer was found to be the most suitable supporting electrolyte for detection of amitraz and its degradants in terms of sensitivity and reproducibility. Studies performed using environmental samples showed that the sensitivity and reproducibility of amitraz and 2,4-dimethylaniline analyses in spent cattle dip were comparable to analyses of amitraz and 2,4-dimethylaniline performed in Britton-Robinson buffer. In addition, the feasibility qf measuring amitraz and 2,4-dimethylaniline in environmental samples was assessed and compared to amitraz and 2,4-dimethylaniline analyses in Britton-Robinson buffer. Amitraz and 2,4-dimethylaniline were readily detectable in milk and honey. Furthermore, it was elucidated that 2,4-dimethylaniline can be metabolised to 3-methylcatechol by Pseudomonas species and the proposed breakdown pathway is presented. The biological degradation of amitraz and subsequent formation of 2,4-dimethylaniline was readily monitored in spent cattle dip. The breakdown of amitraz to 2,4-dimethylaniline and then to 3-MC was monitored using cyclic voltammetry.
- Full Text:
- Date Issued: 2006
What does the movement of the Phloem-mobile symplastic tracer, 5,6-carboxyfluorescein in shoots of Pisum Sativum L. Indicate - the existence of a symplastic transport system? - a bid to answer some puzzling questions
- Ade-Ademilua, Omobolanle Elizabeth, Botha, Christiaan E J
- Authors: Ade-Ademilua, Omobolanle Elizabeth , Botha, Christiaan E J
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6492 , http://hdl.handle.net/10962/d1004475 , http://dx.doi.org/10.3923/ajpp.2006.127.131
- Description: Like other members of the Fabaceae, the minor veins of Pisum are categorized as a closed system termed type 2 minor vein configuration due to the presence of few or no plasmodesmal connections between the sieve element-transfer cell complex (SE-TCC) and the adjacent cells (Gamalei, 1989; van Bel and Gamalei, 1991) Pisum is classified further into the category of type 2 b minor vein configuration due to the presence of transfer cells with the characteristic wall ingrowths in the minor vein phloem (Gamalei, 1989). According to van Bel et al. (1992), there is a correlation between minor vein configuration and phloem loading. However, by reason of low plasmodesmal frequency, the pathway of the flow of assimilates in plants with type 2 minor vein configuration is considered to be apoplasmic (Gamalei, 1989; van Bel and Gamalei, 1991). Therefore, present reports on the movement of phloem-mobile 5,6-carboxyfluorescein, a known symplamically transported compound between pea leaflets raises some doubts on the accession that transport within the phloem in pea is strictly apoplasmic. In this study we look at different points of arguments and try to offer our explanation and conclusions on the transport pathways that are likely to exist in Pisum.
- Full Text: false
- Date Issued: 2006
- Authors: Ade-Ademilua, Omobolanle Elizabeth , Botha, Christiaan E J
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6492 , http://hdl.handle.net/10962/d1004475 , http://dx.doi.org/10.3923/ajpp.2006.127.131
- Description: Like other members of the Fabaceae, the minor veins of Pisum are categorized as a closed system termed type 2 minor vein configuration due to the presence of few or no plasmodesmal connections between the sieve element-transfer cell complex (SE-TCC) and the adjacent cells (Gamalei, 1989; van Bel and Gamalei, 1991) Pisum is classified further into the category of type 2 b minor vein configuration due to the presence of transfer cells with the characteristic wall ingrowths in the minor vein phloem (Gamalei, 1989). According to van Bel et al. (1992), there is a correlation between minor vein configuration and phloem loading. However, by reason of low plasmodesmal frequency, the pathway of the flow of assimilates in plants with type 2 minor vein configuration is considered to be apoplasmic (Gamalei, 1989; van Bel and Gamalei, 1991). Therefore, present reports on the movement of phloem-mobile 5,6-carboxyfluorescein, a known symplamically transported compound between pea leaflets raises some doubts on the accession that transport within the phloem in pea is strictly apoplasmic. In this study we look at different points of arguments and try to offer our explanation and conclusions on the transport pathways that are likely to exist in Pisum.
- Full Text: false
- Date Issued: 2006
What matters in economics teaching and learning? A case study of an introductory macroeconomics course in South Africa
- Snowball, Jeanette D, Wilson, M K
- Authors: Snowball, Jeanette D , Wilson, M K
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68500 , vital:29270 , https://doi.org/10.19030/tlc.v3i11.1659
- Description: Publisher version , In many universities, economics lecturers now face the challenge of dealing with large, diverse classes, especially at undergraduate level. A common concern is the non-attendance at lectures of unmotivated (conscript) students. Poor lecture quality, as reflected in student evaluations of teaching (SETs), is often blamed for lack of attendance and consequent poor performance. This paper presents the results of a student assessment of a macroeconomics 1 course, coupled with a self-assessment of their own input into the course. The results obtained, using econometric models, suggest that students inputs and attitudes to the course are equally, or more, important than lecture attendance itself.
- Full Text:
- Date Issued: 2006
- Authors: Snowball, Jeanette D , Wilson, M K
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68500 , vital:29270 , https://doi.org/10.19030/tlc.v3i11.1659
- Description: Publisher version , In many universities, economics lecturers now face the challenge of dealing with large, diverse classes, especially at undergraduate level. A common concern is the non-attendance at lectures of unmotivated (conscript) students. Poor lecture quality, as reflected in student evaluations of teaching (SETs), is often blamed for lack of attendance and consequent poor performance. This paper presents the results of a student assessment of a macroeconomics 1 course, coupled with a self-assessment of their own input into the course. The results obtained, using econometric models, suggest that students inputs and attitudes to the course are equally, or more, important than lecture attendance itself.
- Full Text:
- Date Issued: 2006
Where have all the fathers gone? Media(ted) representations of fatherhood.
- Authors: Prinsloo, J
- Date: 2006
- Language: English
- Type: Book review
- Identifier: vital:530 , http://hdl.handle.net/10962/d1008483
- Description: [From the introduction]: "It is in the mundane world that media operate most significantly. They filter and frame everyday realities, through their singular and multiple representations, providing touchstones, references, for the conduct of everyday life, for the production and maintenance of common-sense (Silverstone 1999, p.6). While it is broadly accepted that the media do not reflect society, they do provide us with a repertoire of roles and images which we encounter and with which we engage." As the opening quote suggests, the media play a vital role in the circulation and mediation of ideas, attitudes and actions and their significance is commented on frequently. It is noteworthy that such commentary in South Africa identifies that men are infrequently depicted in parental roles. This is in comparison to the other roles men inhabit and in contrast to the role of women as mother. It is also suggested that the macho masculine identities that the media offer serve as proxy father roles.
- Full Text:
- Date Issued: 2006
- Authors: Prinsloo, J
- Date: 2006
- Language: English
- Type: Book review
- Identifier: vital:530 , http://hdl.handle.net/10962/d1008483
- Description: [From the introduction]: "It is in the mundane world that media operate most significantly. They filter and frame everyday realities, through their singular and multiple representations, providing touchstones, references, for the conduct of everyday life, for the production and maintenance of common-sense (Silverstone 1999, p.6). While it is broadly accepted that the media do not reflect society, they do provide us with a repertoire of roles and images which we encounter and with which we engage." As the opening quote suggests, the media play a vital role in the circulation and mediation of ideas, attitudes and actions and their significance is commented on frequently. It is noteworthy that such commentary in South Africa identifies that men are infrequently depicted in parental roles. This is in comparison to the other roles men inhabit and in contrast to the role of women as mother. It is also suggested that the macho masculine identities that the media offer serve as proxy father roles.
- Full Text:
- Date Issued: 2006
White women writing white : a study of identity and representation in (post-)apartheid literatures of South Africa
- Authors: West, Mary Eileen
- Date: 2006
- Subjects: South African fiction (English) -- History and criticism , Identity (Psychology)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8443 , http://hdl.handle.net/10948/442 , South African fiction (English) -- History and criticism , Identity (Psychology)
- Description: This thesis examines aspects of identity and representation using contemporary theories and definitions emerging out of a growing body of work known as whiteness studies. The condition of whiteness as it continues to inform identity politics in post-apartheid South Africa is explored in an analysis of selected texts written by white women, to demonstrate the ways in which whiteness continues to suggest normativity. In reading a representative selection of literatures produced in contemporary South Africa by white women writers, this study aims to illustrate the ambivalence apparent in the interstitial manifestations of emergent reconciliatory gestures that are at odds with residual traces of superiority. A sampling of disparate texts is examined to explore the representations of race and belonging in post-apartheid South Africa in the light of contemporary theories of whiteness which posit it as a powerful and invisible identification. The analysis attempts to plot a continuum from writers who are least, through to those who are most, aware of whiteness as a cultural construct and of their own positionality in relation to the discursive dynamics that inform South African racial politics. A contextualising overview of the terrain of whiteness studies is provided in Chapter One, marking the ideological and theoretical affiliations of this project, and foregrounding the construction of whiteness as an imagined identity in contemporary cultural criticism. It also provides a justification for the selection of the textual material under scrutiny. Chapter Two explores a genre that has been identified as a growing trend in South African fiction: the production of pulp fiction written by white middle-class women. Two such texts are the focus of this chapter, namely, Pamela Jooste’s People like Ourselves (2004) and Susan Mann’s One Tongue Singing (2005), and the complicities and clichés that are characteristic of popular literature are examined. Antjie Krog’s A Change of Tongue (2003) is the focus of Chapter Three. It is examined as a book offering the writer’s personal response to the difficulties of transformation within the first decade of South African democracy. Krog confronts her own defensiveness, her sense of normalcy, and her sense of alienation in relation to multiple encounters with different people. Chapter Four focuses on the journalism of Marianne Thamm. Her role as columnist for the popular women’s magazine, Fairlady is explored, particularly in relation to the inclusion of a contending voice writing against the general tenets of Fairlady. Thamm’s critique of the mores governing bourgeois white womanhood is read in relation to her role as officially sanctioned Court Jester. Her Fairlady columns have been collected in Mental Floss (2002) but the analysis includes selected columns from 2003 to 2005. Echo Location: A Guide to Sea Point for Residents and Visitors (1998) by Karen Press is the focus of Chapter Five. Her work is read as examining a white South African crisis of belonging in relation to the implications of mapping the co-ordinates of whiteness in South Africa. Chapter Six offers a reading of four short stories, written by Nadine Gordimer and Marlene van Niekerk. These stories are juxtaposed to trace an anxious impasse in white responses to suburbia, the place of enactment of white bourgeois mores, which both writers interrogate.
- Full Text:
- Date Issued: 2006
- Authors: West, Mary Eileen
- Date: 2006
- Subjects: South African fiction (English) -- History and criticism , Identity (Psychology)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8443 , http://hdl.handle.net/10948/442 , South African fiction (English) -- History and criticism , Identity (Psychology)
- Description: This thesis examines aspects of identity and representation using contemporary theories and definitions emerging out of a growing body of work known as whiteness studies. The condition of whiteness as it continues to inform identity politics in post-apartheid South Africa is explored in an analysis of selected texts written by white women, to demonstrate the ways in which whiteness continues to suggest normativity. In reading a representative selection of literatures produced in contemporary South Africa by white women writers, this study aims to illustrate the ambivalence apparent in the interstitial manifestations of emergent reconciliatory gestures that are at odds with residual traces of superiority. A sampling of disparate texts is examined to explore the representations of race and belonging in post-apartheid South Africa in the light of contemporary theories of whiteness which posit it as a powerful and invisible identification. The analysis attempts to plot a continuum from writers who are least, through to those who are most, aware of whiteness as a cultural construct and of their own positionality in relation to the discursive dynamics that inform South African racial politics. A contextualising overview of the terrain of whiteness studies is provided in Chapter One, marking the ideological and theoretical affiliations of this project, and foregrounding the construction of whiteness as an imagined identity in contemporary cultural criticism. It also provides a justification for the selection of the textual material under scrutiny. Chapter Two explores a genre that has been identified as a growing trend in South African fiction: the production of pulp fiction written by white middle-class women. Two such texts are the focus of this chapter, namely, Pamela Jooste’s People like Ourselves (2004) and Susan Mann’s One Tongue Singing (2005), and the complicities and clichés that are characteristic of popular literature are examined. Antjie Krog’s A Change of Tongue (2003) is the focus of Chapter Three. It is examined as a book offering the writer’s personal response to the difficulties of transformation within the first decade of South African democracy. Krog confronts her own defensiveness, her sense of normalcy, and her sense of alienation in relation to multiple encounters with different people. Chapter Four focuses on the journalism of Marianne Thamm. Her role as columnist for the popular women’s magazine, Fairlady is explored, particularly in relation to the inclusion of a contending voice writing against the general tenets of Fairlady. Thamm’s critique of the mores governing bourgeois white womanhood is read in relation to her role as officially sanctioned Court Jester. Her Fairlady columns have been collected in Mental Floss (2002) but the analysis includes selected columns from 2003 to 2005. Echo Location: A Guide to Sea Point for Residents and Visitors (1998) by Karen Press is the focus of Chapter Five. Her work is read as examining a white South African crisis of belonging in relation to the implications of mapping the co-ordinates of whiteness in South Africa. Chapter Six offers a reading of four short stories, written by Nadine Gordimer and Marlene van Niekerk. These stories are juxtaposed to trace an anxious impasse in white responses to suburbia, the place of enactment of white bourgeois mores, which both writers interrogate.
- Full Text:
- Date Issued: 2006
Will the invasive mussel Mytilus galloprovincialis Lamarck replace the indigenous Perna perna L. on the south coast of South Africa?
- Bownes, Sarah J, McQuaid, Christopher D
- Authors: Bownes, Sarah J , McQuaid, Christopher D
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6926 , http://hdl.handle.net/10962/d1011914
- Description: The mussel Mytilus galloprovincialis is invasive worldwide, has displaced indigenous species on the west coast of South Africa and now threatens Perna perna on the south coast. We tested the hypothesis that Mytilus will replace Perna by examining changes in their distribution on shores where they co-exist. Total cover, adult density, recruit density, recruit/adult correlations and mean maximum lengths of both species were measured in 2001 at two contrasting sites (Plettenberg Bay and Tsitsikamma) 70 km apart, each including two locations 100 m apart. Cover and density were measured again in 2004. Total mussel abundance was significantly lower in Tsitsikamma, and recruit density was only 17% that of Plettenberg Bay. Abundance and cover increased upshore for Mytilus, but decreased for Perna, giving Mytilus higher adult and recruit density and total cover than Perna in the upper zones. Low shore densities of recruits and adults were similar between species but cover was lower for Mytilus, reflecting its smaller size, and presumably slower growth or higher mortality there. Thus, mechanisms excluding species differed among zones. Recruitment limitation delays invasion at Tsitsikamma and excludes Perna from the high shore, while Mytilus is excluded from the low shore by post-recruitment effects. Recruitment limitation also shapes population structure. Recruit/adult correlations were significant only where adult densities were low, and this effect was species-specific. Thus, at low densities, larvae settle or survive better near adult conspecifics. After 3 years, these patterns remained strongly evident, suggesting Mytilus will not eliminate Perna and that co-existence is possible through partial habitat segregation driven by recruitment limitation of Perna on the high shore and post-settlement effects on Mytilus on the low shore.
- Full Text:
- Date Issued: 2006
- Authors: Bownes, Sarah J , McQuaid, Christopher D
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6926 , http://hdl.handle.net/10962/d1011914
- Description: The mussel Mytilus galloprovincialis is invasive worldwide, has displaced indigenous species on the west coast of South Africa and now threatens Perna perna on the south coast. We tested the hypothesis that Mytilus will replace Perna by examining changes in their distribution on shores where they co-exist. Total cover, adult density, recruit density, recruit/adult correlations and mean maximum lengths of both species were measured in 2001 at two contrasting sites (Plettenberg Bay and Tsitsikamma) 70 km apart, each including two locations 100 m apart. Cover and density were measured again in 2004. Total mussel abundance was significantly lower in Tsitsikamma, and recruit density was only 17% that of Plettenberg Bay. Abundance and cover increased upshore for Mytilus, but decreased for Perna, giving Mytilus higher adult and recruit density and total cover than Perna in the upper zones. Low shore densities of recruits and adults were similar between species but cover was lower for Mytilus, reflecting its smaller size, and presumably slower growth or higher mortality there. Thus, mechanisms excluding species differed among zones. Recruitment limitation delays invasion at Tsitsikamma and excludes Perna from the high shore, while Mytilus is excluded from the low shore by post-recruitment effects. Recruitment limitation also shapes population structure. Recruit/adult correlations were significant only where adult densities were low, and this effect was species-specific. Thus, at low densities, larvae settle or survive better near adult conspecifics. After 3 years, these patterns remained strongly evident, suggesting Mytilus will not eliminate Perna and that co-existence is possible through partial habitat segregation driven by recruitment limitation of Perna on the high shore and post-settlement effects on Mytilus on the low shore.
- Full Text:
- Date Issued: 2006
Wireless Ethernet Propagation Modeling Software
- Janse van Rensburg, Johanna, Irwin, Barry V W
- Authors: Janse van Rensburg, Johanna , Irwin, Barry V W
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428249 , vital:72497
- Description: Wireless technologies have had an enormous impact on networking in recent years. It can create new business oppurtunities and allow users to communicate and share data in a new fashion. Wireless Networks decrease installation costs, reduce the deployment time of a network and overcome physical barrier problems inherent in wiring. Unfortunately this flexibility comes at a price. The deployment, installation and setup of a WLAN is not a simple task and a number of factors need to be con-sidered. Wireless Networks are notorious for being insecure due to signal spill, ad-hoc unauthorized access points and varying encryption strengths and standards. RF (Radio Frequency) interference and physical barriers suppress a signal. In addition the channel frequencies each access point will be using in order to provide maxi-mum roaming but minimum inter access point interference need to be considered. It is a complex balancing act to take these factors into account while still maintaining coverage, performance and security requirements. In this paper the benefits and feasibility of a model will be discussed that will enable the network administrator to visualize the coverage footprint of their wireless network when the above factors are taken into consideration. The program will be able to predict the strength, prop-agation and unwanted spill of signals which could compromise the security of an organisation prior to the deployment of a WLAN. In addition the model will provide functionality to visualize a signal from audit data once the WLAN is operational. The end result will be a program that can aid in the configuration, installation and man-agement of a secure WLAN.
- Full Text:
- Date Issued: 2006
- Authors: Janse van Rensburg, Johanna , Irwin, Barry V W
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428249 , vital:72497
- Description: Wireless technologies have had an enormous impact on networking in recent years. It can create new business oppurtunities and allow users to communicate and share data in a new fashion. Wireless Networks decrease installation costs, reduce the deployment time of a network and overcome physical barrier problems inherent in wiring. Unfortunately this flexibility comes at a price. The deployment, installation and setup of a WLAN is not a simple task and a number of factors need to be con-sidered. Wireless Networks are notorious for being insecure due to signal spill, ad-hoc unauthorized access points and varying encryption strengths and standards. RF (Radio Frequency) interference and physical barriers suppress a signal. In addition the channel frequencies each access point will be using in order to provide maxi-mum roaming but minimum inter access point interference need to be considered. It is a complex balancing act to take these factors into account while still maintaining coverage, performance and security requirements. In this paper the benefits and feasibility of a model will be discussed that will enable the network administrator to visualize the coverage footprint of their wireless network when the above factors are taken into consideration. The program will be able to predict the strength, prop-agation and unwanted spill of signals which could compromise the security of an organisation prior to the deployment of a WLAN. In addition the model will provide functionality to visualize a signal from audit data once the WLAN is operational. The end result will be a program that can aid in the configuration, installation and man-agement of a secure WLAN.
- Full Text:
- Date Issued: 2006
Wireless Security Tools
- Janse van Rensburg, Johanna, Irwin, Barry V W
- Authors: Janse van Rensburg, Johanna , Irwin, Barry V W
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429867 , vital:72647 , https://digifors.cs.up.ac.za/issa/2006/Proceedings/Research/113_Paper.pdf
- 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 method. The method entails a combination of network telescope traffic capture and visualisation. Observing traffic from the perspective of a dedicated sensor network reduces the volume of data and alleviates the concern of confusing malicious traffic with legitimate traffic. Com-plimenting this, visual analysis facilitates the rapid review and correla-tion of events, thereby utilizing human intelligence in the identification of scanning patterns. To demonstrate the proposed method, several months of network telescope traffic is captured and analysed with a tai-lor made 3D scatter-plot visualisation. As the results show, the visuali-sation saliently conveys anomalous patterns, and further analysis re-veals that these patterns are indicative of covert network probing activi-ty. By incorporating visual analysis with traditional approaches, such as textual log review and the use of an intrusion detection system, this re-search contributes improved insight into network scanning incidents.
- Full Text:
- Date Issued: 2006
- Authors: Janse van Rensburg, Johanna , Irwin, Barry V W
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429867 , vital:72647 , https://digifors.cs.up.ac.za/issa/2006/Proceedings/Research/113_Paper.pdf
- 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 method. The method entails a combination of network telescope traffic capture and visualisation. Observing traffic from the perspective of a dedicated sensor network reduces the volume of data and alleviates the concern of confusing malicious traffic with legitimate traffic. Com-plimenting this, visual analysis facilitates the rapid review and correla-tion of events, thereby utilizing human intelligence in the identification of scanning patterns. To demonstrate the proposed method, several months of network telescope traffic is captured and analysed with a tai-lor made 3D scatter-plot visualisation. As the results show, the visuali-sation saliently conveys anomalous patterns, and further analysis re-veals that these patterns are indicative of covert network probing activi-ty. By incorporating visual analysis with traditional approaches, such as textual log review and the use of an intrusion detection system, this re-search contributes improved insight into network scanning incidents.
- Full Text:
- Date Issued: 2006
Work methods and procedures for plague surveillance and control in South Africa
- Authors: Zhou, Hongxing
- Date: 2006
- Subjects: Plague -- South Africa , Plague -- Vaccination
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9833 , http://hdl.handle.net/10948/649 , Plague -- South Africa , Plague -- Vaccination
- Description: Plague is a classic zoonosis caused by the bacterium Yersinia pestis and is subject to the International Health Regulations, 1969. In the last two millennia, plague has become widespread, with three pandemics occurring in the 6th, 14th and 20th centuries. Currently, plague outbreaks and epidemics still occur worldwide. This study attempts to develop formal work methods and procedures for plague surveillance and control by environmental health practitioners as a strategy to ensure that field data can be integrated within the municipal, provincial and national spheres of government. A qualitative, explorative, descriptive, inductive and deductive research design was followed. A documentary research approach was employed as the primary method of data collection. To obtain additional information, both semi-structured personal interviews and physical observations during plague surveillance were adopted by the researcher. The organisational structure of the health care system in South Africa was analysed to identify and explain the role and functions of relevant decision-makers related to the surveillance and control of plague within the different spheres of government. Legislative measures regarding plague surveillance and control were also presented. As a prerequisite for the development of work methods and procedures for plague surveillance and control, the epidemiology of plague was discussed with emphasis on the distribution and characteristics of the disease in South Africa. Important rodent reservoirs and flea vectors of plague in South Africa were identified. Clinical manifestations, diagnosis and treatment of plague were described and discussed. Within this qualitative study an attempt has been made to develop work methods (xiii) and procedures for plague surveillance and control in South Africa. Relevant field data forms to be used during plague surveillance and control strategies were also developed. Recommendations emanating from the study can be found in the final chapter.
- Full Text:
- Date Issued: 2006
- Authors: Zhou, Hongxing
- Date: 2006
- Subjects: Plague -- South Africa , Plague -- Vaccination
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9833 , http://hdl.handle.net/10948/649 , Plague -- South Africa , Plague -- Vaccination
- Description: Plague is a classic zoonosis caused by the bacterium Yersinia pestis and is subject to the International Health Regulations, 1969. In the last two millennia, plague has become widespread, with three pandemics occurring in the 6th, 14th and 20th centuries. Currently, plague outbreaks and epidemics still occur worldwide. This study attempts to develop formal work methods and procedures for plague surveillance and control by environmental health practitioners as a strategy to ensure that field data can be integrated within the municipal, provincial and national spheres of government. A qualitative, explorative, descriptive, inductive and deductive research design was followed. A documentary research approach was employed as the primary method of data collection. To obtain additional information, both semi-structured personal interviews and physical observations during plague surveillance were adopted by the researcher. The organisational structure of the health care system in South Africa was analysed to identify and explain the role and functions of relevant decision-makers related to the surveillance and control of plague within the different spheres of government. Legislative measures regarding plague surveillance and control were also presented. As a prerequisite for the development of work methods and procedures for plague surveillance and control, the epidemiology of plague was discussed with emphasis on the distribution and characteristics of the disease in South Africa. Important rodent reservoirs and flea vectors of plague in South Africa were identified. Clinical manifestations, diagnosis and treatment of plague were described and discussed. Within this qualitative study an attempt has been made to develop work methods (xiii) and procedures for plague surveillance and control in South Africa. Relevant field data forms to be used during plague surveillance and control strategies were also developed. Recommendations emanating from the study can be found in the final chapter.
- Full Text:
- Date Issued: 2006
Yours, mine and ours: intellectual property
- Authors: Garman, Anthea
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158784 , vital:40228 , https://hdl.handle.net/10520/EJC146169
- Description: When Grocott's Mail in Grahamstown wanted to use the Hector Pieterson photograph for the front cover of a Youth Day supplement celebrating the courage of the Soweto students of 1976, they decided to go the official route by contacting the photographer's agent and paying for the picture. They were told a single use would cost them thousands of rands. Obviously an impossibility for a small-town, community newspaper.
- Full Text:
- Date Issued: 2006
- Authors: Garman, Anthea
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158784 , vital:40228 , https://hdl.handle.net/10520/EJC146169
- Description: When Grocott's Mail in Grahamstown wanted to use the Hector Pieterson photograph for the front cover of a Youth Day supplement celebrating the courage of the Soweto students of 1976, they decided to go the official route by contacting the photographer's agent and paying for the picture. They were told a single use would cost them thousands of rands. Obviously an impossibility for a small-town, community newspaper.
- Full Text:
- Date Issued: 2006
Zambia African Media Development Initiative (AMDI) research report
- Authors: Banda, Fackson
- Date: 2006
- Language: English
- Type: Report
- Identifier: vital:533 , http://hdl.handle.net/10962/d1008546
- Description: This report is one of 18 produced as part of the African Media Development Initiative Research Project, completed in 2006. Firstly, the study outlines the major media development initiatives that have taken place in the Zambian media and communication landscape since 2000. Secondly, it analyses how key actors view these initiatives, in the light of wider media development programmes unfolding on the African continent. Thirdly, it gives a case study of one particularly insightful media development activity in the country. On the whole, the study concludes that the radio sector has grown since 2000. Television has received little investment because the state has more control over this sector. The past five years have seen a growth in better-coordinated media development initiatives. The content of the media has itself become diversified, but there is still a prepoderance of urban-based, elite voices.
- Full Text:
- Date Issued: 2006
- Authors: Banda, Fackson
- Date: 2006
- Language: English
- Type: Report
- Identifier: vital:533 , http://hdl.handle.net/10962/d1008546
- Description: This report is one of 18 produced as part of the African Media Development Initiative Research Project, completed in 2006. Firstly, the study outlines the major media development initiatives that have taken place in the Zambian media and communication landscape since 2000. Secondly, it analyses how key actors view these initiatives, in the light of wider media development programmes unfolding on the African continent. Thirdly, it gives a case study of one particularly insightful media development activity in the country. On the whole, the study concludes that the radio sector has grown since 2000. Television has received little investment because the state has more control over this sector. The past five years have seen a growth in better-coordinated media development initiatives. The content of the media has itself become diversified, but there is still a prepoderance of urban-based, elite voices.
- Full Text:
- Date Issued: 2006
‘Exploring the practical adequacy of the human rights, social justice, inclusivity and healthy environment policy discourse in South Africa’s National Curriculum Statement’
- Schudel, Ingrid, Lotz-Sisitka, Heila
- Authors: Schudel, Ingrid , Lotz-Sisitka, Heila
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391180 , vital:68629 , xlink:href="https://www.tandfonline.com/doi/full/10.1080/13504620701284860"
- Description: This article examines the practical adequacy of the recent defining of a normative framework for the South African National Curriculum Statement that focuses on the relationship between human rights, social justice and a healthy environment. This politically framed and socially critical normative framework has developed in response to socio-political and socio-ecological histories in postapartheid curriculum transformation processes. The article critically considers the process of working with a normative framework in the defining of environmental education teaching and learning interactions, and seeks not only to explore the policy discourse critically, but also to explore what it is about the world that makes it work in different ways. Drawing on Sayer’s perspectives on the possibilities of enabling ‘situated universalism’ as a form of normative theory, and case-based data from a teacher professional development programme in the Makana District (where the authors live and work), the article probes the relationship between the establishment of a ‘universalising’ normative framework to guide national curriculum, and situated engagements with this framework in/as democratic process. In this process it questions whether educators should adopt the ‘norms’ as presented by society and simply universalize and implement them as prescribed by curriculum statements, or whether educators should adopt the strategies of postmodernists and reduce normative frameworks to relations of power situated in particular contexts.
- Full Text:
- Date Issued: 2006
- Authors: Schudel, Ingrid , Lotz-Sisitka, Heila
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391180 , vital:68629 , xlink:href="https://www.tandfonline.com/doi/full/10.1080/13504620701284860"
- Description: This article examines the practical adequacy of the recent defining of a normative framework for the South African National Curriculum Statement that focuses on the relationship between human rights, social justice and a healthy environment. This politically framed and socially critical normative framework has developed in response to socio-political and socio-ecological histories in postapartheid curriculum transformation processes. The article critically considers the process of working with a normative framework in the defining of environmental education teaching and learning interactions, and seeks not only to explore the policy discourse critically, but also to explore what it is about the world that makes it work in different ways. Drawing on Sayer’s perspectives on the possibilities of enabling ‘situated universalism’ as a form of normative theory, and case-based data from a teacher professional development programme in the Makana District (where the authors live and work), the article probes the relationship between the establishment of a ‘universalising’ normative framework to guide national curriculum, and situated engagements with this framework in/as democratic process. In this process it questions whether educators should adopt the ‘norms’ as presented by society and simply universalize and implement them as prescribed by curriculum statements, or whether educators should adopt the strategies of postmodernists and reduce normative frameworks to relations of power situated in particular contexts.
- Full Text:
- Date Issued: 2006