Impacts of wildlife and cattle grazing on spider (araneae) biodiversity in a highland savanna ecosystem, in Laikipia, Central Kenya
- Authors: Warui, Charles Mwaura
- Date: 2005
- Subjects: Spiders -- Kenya Environmental monitoring -- Kenya Savanna ecology -- Kenya Biodiversity -- Kenya Species diversity -- Kenya Wildlife management -- Kenya Herbivores -- Ecology -- Kenya
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5712 , http://hdl.handle.net/10962/d1005398
- Description: Spiders were sampled at Mpala Research Centre, Laikipia, Kenya by pitfall-trapping and sweep-netting from May 2001 to July 2002, at a Kenyan Long-term Exclosure Experiment. The aim was to establish species composition, checklist and examine spider responses to disturbances caused by cattle, megaherbivores (giraffe and elephants) and mesoherbivores (other ungulates) by looking at three levels of resolution, namely the overall community, guilds and individual species. This is the first controlled replicated experimental study on the effects on invertebrates (spiders) by different land uses (access by large herbivores). A total of 10,487 individuals from 132 species belonging to 30 families were recorded. The family Salticidae had the highest number of species (24), followed by Gnaphosidae (20), Araneidae and Lycosidae (15 each), Theridiidae and Thomisidae (8 each) and Zodariidae (4). Most of the other families had fewer than 4 species. Throughout the study period, species not previously sampled emerged after rainfall peaks. Exclosure treatments affected plant cover, spider diversity and total species mainly through the effects of cattle, whose presence significantly reduced relative vegetation cover. An increase in vegetation cover significantly increased the diversity, total species and species evenness of the overall spider community (total samples data set). Megaherbivores and mesoherbivores had no effects on overall spider diversity. Relative vegetation cover explained approximately 20-30% of variation in community diversity, species richness and species evenness. At the guild level of resolution, the exclosure treatments had no significant effects on diversity, species richness and species evenness of web builders, plant wanderers and ground wanderers. Plant wanderers were significantly and positively correlated with relative vegetation cover, which explained 17% of variation in their diversity. Six individual species responded strongly and in contrasting ways to the same environmental variables, indicating that this level was more sensitive to environmental changes than guilds or the overall spider community. Spider diversity, relative vegetation cover and rainfall varied at a temporal scale of months and not at a spatial scale of hundreds of metres. Only species diversity and species richness from sweep-netting samples and total species from pitfall-trapping varied significantly at a spatial scale of hundreds of metres. Ordination analysis revealed that sweep-netting samples were a better indicator of grazing impacts than pitfalltrapping or combined samples and grouped to reflect cattle grazing, non-cattle grazing and to a small extent the control treatments. Other ordination analyses showed that only samples from sweep-netting and not from pitfall-trapping, were spatially partitioned at a scale of hundreds of metres. This study concludes that the spider fauna of black cotton soil habitats is rich and useful for environmental monitoring and that monitoring of several individual species as indicator of grazing impacts in savanna could be useful and relatively easy.
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Implementing an EPrints repository system at a small South African university
- Authors: Vermaak, Irene
- Date: 2005
- Language: English
- Type: Text
- Identifier: vital:6980 , http://hdl.handle.net/10962/d1012408
- Description: This presentation gives a descriptive and analytical overview of the implementation of the Rhodes eResearch Repository system at Rhodes University, building on an ETD programme started in 1998. This project involves staff from Rhodes University Library and the Information Technology Division, with the approval of the Dean of Research. With the support of Management and a strong university IT culture of using open source software, Rhodes University Library planned the implementation of the system without major bureaucratic obstacles. We did, however, experience limited budgetary support and severe staff constraints. This poster aims to encourage institutions with limited resources to start IR programmes and emphasizes the short space of time required “to get up and go”.
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In vitro release of ketoprofen from proprietary and extemporaneously manufactured gels
- Authors: Tettey-Amlalo, Ralph Nii Okai
- Date: 2005
- Subjects: Transdermal medication , Drug delivery systems , High performance liquid chromatography , Nonsteroidal anti-inflammatory agents , Rheumatoid arthritis -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3797 , http://hdl.handle.net/10962/d1003275 , Transdermal medication , Drug delivery systems , High performance liquid chromatography , Nonsteroidal anti-inflammatory agents , Rheumatoid arthritis -- Treatment
- Description: Ketoprofen is a potent non-steroidal anti-inflammatory drug which is used for the treatment of rheumatoid arthritis. The oral administration of ketoprofen can cause gastric irritation and adverse renal effects. Transdermal delivery of the drug can bypass gastrointestinal disturbances and provide relatively consistent drug concentrations at the site of administration. The release of ketoprofen from proprietary gel products from three different countries was evaluated by comparing the in vitro release profiles. Twenty extemporaneously prepared ketoprofen gel formulations using Carbopol® polymers were manufactured. The effect of polymer, drug concentration, pH and solvent systems on the in vitro release of ketoprofen from these formulations were investigated. The gels were evaluated for drug content and pH. The release of the drug from all the formulations obeyed the Higuchi principle. Two static FDA approved diffusion cells, namely the modified Franz diffusion cell and the European Pharmacopoeia diffusion cell, were compared by measuring the in vitro release rate of ketoprofen from all the gel formulations through a synthetic silicone membrane. High-performance liquid chromatography and ultraviolet spectrophotometric analytical techniques were both used for the analysis of ketoprofen. The validated methods were employed for the determination of ketoprofen in the sample solutions taken from the receptor fluid. Two of the three proprietary products registered under the same manufacturing license exhibited similar results whereas the third product differed significantly. Among the variables investigated, the vehicle pH and solvent composition were found have the most significant effect on the in vitro release of ketoprofen from Carbopol® polymers. The different grades of Carbopol® polymers showed statistically significantly different release kinetics with respect to lag time. When evaluating the proprietary products, both the modified Franz diffusion cell and the European Pharmacopoeia diffusion cell were deemed adequate although higher profiles were generally obtained from the European Pharmacopoeia diffusion cells. Smoother diffusion profiles were obtained from samples analysed by high-performance liquid chromatography than by ultraviolet spectrophotometry in both diffusion cells. Sample solutions taken from Franz diffusion cells and analysed by ultraviolet spectrophotometry also produced smooth diffusion profiles. Erratic and higher diffusion profiles were observed with samples taken from the European Pharmacopoeia diffusion cell and analysed by ultraviolet spectrophotometry. The choice of diffusion cells and analytical procedure in product development must be weighed against the relatively poor reproducibility as observed with the European Pharmacopoeia diffusion cell.
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In-kernel cryptographic executable verification
- Authors: Motara, Yusuf, M , Irwin, Barry V W
- Date: 2005
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429049 , vital:72556 , https://doi.org/10.1007/0-387-31163-7_25
- Description: This paper discusses the problems posed by Trojan horses and unauthorized code, and reviews existing solutions for dealing with them. A technique involving the in-kernel verification of executables is proposed. Its advantages include simplicity, transparency, ease of use and minimal setup time. In addition, the technique has several applications, including assisting with honeypot implementations, incident response and forensic investigations.
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In-kernel cryptographic executable verification
- Authors: Motara, Yusuf, M , Irwin, Barry V W
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429937 , vital:72653 , https://doi.org/10.1007/0-387-31163-7_25
- Description: This paper discusses the problems posed by Trojan horses and unau-thorized code, and reviews existing solutions for dealing with them. A technique involving the in-kernel verification of executables is pro-posed. Its advantages include simplicity, transparency, ease of use and minimal setup time. In addition, the technique has several applications, including assisting with honeypot implementations, incident response and forensic investigations.
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Incorporating indigenous management in rock art sites in KwaZulu-Natal
- Authors: Ndlovu, Ndukuyakhe
- Date: 2005
- Subjects: Rock paintings -- Drakenberg Mountains , Cave paintings -- Drakensberg Mountains , San (African people) -- Art , Art, Prehistoric -- Drakensberg Mountains , Art, Prehistoric -- South Africa , Heritage tourism -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2089 , http://hdl.handle.net/10962/d1002652 , Rock paintings -- Drakenberg Mountains , Cave paintings -- Drakensberg Mountains , San (African people) -- Art , Art, Prehistoric -- Drakensberg Mountains , Art, Prehistoric -- South Africa , Heritage tourism -- South Africa
- Description: The majestic mountains of the uKhahlamba Drakensberg, formed many millennia ago were home to the Bushmen[footnote 1] or San people. They lived at these mountains for thousands of years before they were colonised by the Bantu speakers and the Europeans. Academic writings for many years have perpetuated the thinking that Bushman people were largely extinct. The dominance of this view in the academic writings was encouraged by historical evidence that Europeans and Bantu speakers hunted and killed Bushmen over the last several centuries. Researchers argue that the extermination of the Bushmen was because they were less human in the eyes of the foreigners, due to cattle raiding. There is still some element of this thinking amongst today’s academics, although research in the last decade is questioning this thinking. The question of whether descendants do exist is relevant to issues of rights of access to ancestral sacred sites, in particular rock art sites. At present, access to rock art sites is granted on qualification as an authentic fee-paying tourist (or affordability) rather than on group rights to a cultural heritage resource (cultural rights). Based on this, I argue that access to rock art sites is based on qualification rather than by right. This is largely driven by an approach that emphasises the physical conservation and financial sustainability of a site, rather than its spiritual maintenance. It has become clear that the interests in rock art by tourists and Bushman descendants are distinct from each other. Tourists have an aesthetic significance for rock art while Bushmen descendants have a spiritual significance for the paintings. Beyond any doubt, the physically based and financially driven approach has brought new challenges to today’s Bushmen descendants, whom in reaffirming their identities now have a new challenge to overcome. Not only are the rock art sites physically threatened but also they have lost much of their spiritual powers. Their fate lies in the hands of heritage officers who must determine access rights to the painted shelters. Both the National Heritage Resources Act and the KwaZulu-Natal Heritage Act acknowledge living heritage. However, the existence of this heritage is judged against the physical approach to rock art management. If the practises of descendants are perceived to be a threat to the rock art, they will not be approved. The case of the Duma is a classic example. Prior to the ritual ceremony at Game Pass Shelter, Kamberg, they were informed of the minimum standards for opening a rock art site to public and rules of how people should behave while visiting painted shelters. While it was evident that there are problems with the two approaches, the spiritual and physical approach, discussed in the thesis, it is important that solutions are identified. I do not believe that one approach on its own will be good enough, for reasons discussed in the thesis. Instead, the two approaches should be implemented together to compliment each other by identifying common grounds. I provide strategies as to how I believe that such a common ground can be reached. In addition, I provide my own analytical thinking as to how these strategies can be achieved. There is no general consensus over which term is appropriate. Both terms are considered by some academics to be derogatory or pejorative (Chennels 2003). San means vagabond and was given to the Bushmen by Khoi-Khoi people, because they considered themselves of a better social class, as they had domesticated animals and were more sedentary than Bushmen. However, according to WIMSA (Thoma 2003) the word San is derived from the Hai||om language meaning “people who gather”. It is normally written Saan but it has been accepted to write San. In 1993 the San requested to be called San when referred to as an entire group. If one refers to individual people/groups they like to be called by their language and cultural name i.e. Khwe, !Kung, !Xun, Ju|’hoansi, ‡Khomani, N|u, |’Auni, Hai||om, etc In this thesis, Bushmen is a preferred term, because it is a better-known term among the people who are central to this study. It is used without any insulting connotations attached to the term.
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Influence of grazing by large mammals on the spider community of a Kenyan savanna biome
- Authors: Warui, Charles M , Villet, Martin H , Young, T P , Jocqué, R
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6889 , http://hdl.handle.net/10962/d1011649 , http://0-www.bioone.org.wam.seals.ac.za/doi/10.1636/CT05-43.1
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Inspectors of education's perceptions of female principalship in the Rundu region of Namibia
- Authors: Kawana, Irene
- Date: 2005
- Subjects: Women school principals -- Namibia -- Rundu , Educational leadership -- Namibia -- Rundu , Sex discrimination in employment -- Namibia , School supervisors -- Namibia -- Attitudes
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2006 , http://hdl.handle.net/10962/d1015746
- Description: While women constitute more than 51% of the population and far outnumber men in teaching positions in Namibia, very few occupy positions of leadership. Male candidates are still favoured for top positions, thereby denying women the chance to gain entrance to these positions. One of the reasons for this imbalance seems to be that, in spite of conscious political effort and legislation, women may still be perceived as less effective leaders than men. This research focused on leadership in education, in particular school principals, and explored the perceptions of female principalship held by school inspectors. Three school inspectors from the Rundu Education Region were purposefully selected and interviewed. Inspectors were selected on the grounds of their considerable influence in the selection and appointment of school principals. The study found that these inspectors favour school principals who show commitment to their work, have good interpersonal working relationships, are caring, good listeners, visionary and produce good results. The inspectors attribute female principals’ success to their traditionally perceived characteristics, such as caring leadership and ability to develop good human relations. Instead of perceiving these qualities as professionally negative (as is sometimes argued in the literature) the inspectors see them as indisputable assets to leadership. The respondents acknowledge the cultural stereotyping that may have influenced male attitudes to women in the past, but argue that good leadership is not specific to gender, but part of the qualities a person possesses, regardless of sex. This study concludes that, contrary to what has been reported in many studies, these inspectors perceive women principals as effective – equal to their male counterparts or sometimes even more effective - because they are caring, well organized and good at communicating and establishing relations with others. Though these qualities are different from the traditional masculine qualities which include independence and emotional strength, the respondents recognize and legitimize them as preferred qualities in current effective leadership practice.
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Institutional change and ecosystem dynamics in the communal areas around Mt Coke State Forest, Eastern Cape, South Africa
- Authors: Cundill, Georgina
- Date: 2005
- Subjects: Biodiversity -- South Africa -- Eastern Cape , Ecosystem management -- South Africa -- Eastern Cape , Natural resources -- Management -- South Africa -- Eastern Cape , Sustainable agriculture -- South Africa -- Eastern Cape , Sustainable development -- South Africa -- Eastern Cape , Rural development -- South Africa -- Eastern Cape , Nature conservation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:4746 , http://hdl.handle.net/10962/d1006959 , Biodiversity -- South Africa -- Eastern Cape , Ecosystem management -- South Africa -- Eastern Cape , Natural resources -- Management -- South Africa -- Eastern Cape , Sustainable agriculture -- South Africa -- Eastern Cape , Sustainable development -- South Africa -- Eastern Cape , Rural development -- South Africa -- Eastern Cape , Nature conservation -- South Africa -- Eastern Cape
- Description: Through a combination of theoretical discussion and case study analysis from two villages in the Eastern Cape Province, South Africa, this thesis explores the relationship between institutional change and ecosystem dynamics through a multi-scale approach that combines local and scientific knowledge. Several conceptual approaches were combined in this study. These included; the Resilience perspective, the Sustainable Rural Livelihoods approach, the Millennium Assessment framework and principles, and the Environmental Entitlements approach. Various participatory research techniques were employed which combined with GIS technologies, existing data sets, and historical records. Common pool resource areas are social spaces, where local values attached to resources are institutionally mediated, politically nuanced, economically interpreted and historically situated. Political driving forces at various scales have played a disproportionate role in local level institutional functioning in the case study area. In particular, inappropriate state-lead interventions into land use planning have weakened local level institutions, and have reduced the ability of the linked social-ecological system to cope with change and uncertainty. People and ecosystems become more vulnerable when driving forces such as political upheaval, economic depression and drought over-lap. However, rural people are not mere spectators in the face of these driving forces; they respond both reactively and proactively to ensure resilience to change and uncertainty. Ecosystems at Mt Coke play a key role during times of crisis in rural livelihoods. These ecosystems have undergone various short-term cyclical changes largely in response to rainfall fluctuations, and some longer-term changes linked to political events and trends that have affected management practices and local institutions over time. Orthodox ecological interpretations of ecosystem change appear to ignore four key factors identified in this study: 1) the role of institutions in shaping access to resources, 2) the demand for resources in rural livelihoods, 3) the dynamic interaction between social and natural systems, and 4) the interaction between social and natural systems across scales of analysis. The future of common pool resource management lies in the combination of local and scientific knowledge through an adaptive management approach that encourages learning and adaptation in local level institutional structures.
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Interacting effects of wave exposure, tidal height and substratum on spatial variation in densities of mussel Perna perna plantigrades
- Authors: McQuaid, Christopher D , Lindsay, Justin R
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6879 , http://hdl.handle.net/10962/d1011635
- Description: A fine time-scale study was undertaken on the effects of wave exposure, tidal height and substratum type on mussel recruit densities on the south coast of South Africa. Prior to sampling, an exposed and a sheltered shore were identified at each of 2 sites (Diaz Cross and High Rocks) 7 km apart. Each shore was divided into 3 shore levels (termed zones) within which 3 substrata (adult mussels, coralline and non-coralline macroalgae) were sampled. Destructive sampling of early (<1 mm) and late (1 to 5 mm) plantigrades was performed daily over 30 d during a period of comparatively high recruitment. Recruitment was synchronised among substrata within zones, but not among zones or between sites. This suggests that larvae will settle on all substrata within a zone, but will prefer some substrata over others. They will not, however, search among zones for favoured substrata. Densities of early (but not late) plantigrades were consistently greater at Diaz Cross than High Rocks, indicating important differences in post-settlement mortality between sites. At both sites, densities of both recruit classes were greater on the low and mid shore than on the high shore. Generally (18 out of 20 comparisons), plantigrade densities within each zone were greater on algae than on adult mussels. Approximately 45% of all recruits collected were found on the foliose coralline alga Corallina, 37% on adult mussels and 18% on the rhodophyte Gelidium pristoides. Without secondary relocation from macroalgae to adult mussel beds, juveniles recruiting onto algae are likely to be lost. On low shore algae, densities of both early and late plantigrades were greater for exposed shores. Densities of plantigrades on the mussel bed and on algae on the mid and high shore were not correlated with exposure. Thus, site, substratum and zone all had significant and interacting effects on the density of recruits on both exposed and sheltered shores. The effect of wave exposure on recruitment, at least on the low shore, suggests that spatial subsidies not only in the form of food supply, but also in the form of larval transport, have a role in structuring mussel populations.
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Interest rate behaviour in a more transparent South African monetary policy environment
- Authors: Ballim, Goolam Hoosen
- Date: 2005
- Subjects: South African Reserve Bank , Monetary policy -- South Africa , Banks and banking -- South Africa , Interest rates -- South Africa , South Africa -- Economic policy , South Africa -- Economic conditions
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1034 , http://hdl.handle.net/10962/d1004462 , South African Reserve Bank , Monetary policy -- South Africa , Banks and banking -- South Africa , Interest rates -- South Africa , South Africa -- Economic policy , South Africa -- Economic conditions
- Description: South Africa introduced inflation targeting as a monetary policy framework in 2000. This marked a sizable shift in monetary policy management from the previous "eclectic" approach and the explicit focus on M3 money supply before that. The study appraises the effectiveness of monetary policy under this new dispensation. However, the analysis does not centre on inflation outcomes, which can be a measure of effectiveness because they are the overriding objective of the South African Reserve Bank in effect, it is possible to have a target-friendly inflation rate for a length of time despite monetary policy that is ambiguous and encourages unpredictability in market interest rates. However, persistent policy opaqueness can, over time, damage a favourable inflation scenario. For instance, if the public is unsure about the Reserve Bank's desired inflation target, price setting in the wage and goods markets may eventually produce an inflation outcome that is higher than the Bank may have intended. Rather, this study adjudicates the effectiveness of monetary policy within the context of policy transparency, which is an intrinsic part of the inflation targeting framework. The study looks at the extent to which monetary policy transparency has enhanced both the anticipatory nature of the market's response to policy actions and the force that policy has on all interest rates in the financial system, particularly long-term rates. These concepts are important because through the transmission mechanism of monetary policy, the more deft market participants are at anticipating future Reserve Bank policy the greater the Bank's ability to steady the economy before the actual policy event. With the aid of regression models to estimate the response of market rates to policy changes, the results show that there is significant movement in market rates in anticipation of policy action, rather than on the day of the event or the day after. Indeed, the estimates for market rates movement on the day of and even the day after the policy action are generally minute. For instance, the R157 long-term government bond yield changes by a significant 41 basis points in response to a one percentage point change in the Reserve Bank's benchmark repo rate in the period between the last policy action and the day preceding the current action. In contrast, the R157 bond yield changes by an insignificant 2 basis points on the day of the current repo rate change and about 1 basis point the day after the current change. The results point to a robust relationship between policy transparency and the market's ability to foresee rate action. If this were not the case, it is likely that there would be persistent market surprise and, hence, noticeable movement in interest rates on the day of the rate action and perhaps even the day after. Another important observation is that monetary policy impacts significantly on both short- and long-term market rates. Again, certifying the robustness of monetary policy under the inflation targeting regime
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International relations and change: a Kuhnian interpretation
- Authors: Schoeman, Jacobus
- Date: 2005
- Subjects: Kuhn, Thomas S Kuhn, Thomas S -- Criticism and interpretation International relations International relations -- Philosophy Knowledge, Theory of
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2830 , http://hdl.handle.net/10962/d1003040
- Description: Using notions of change developed by Thomas Kuhn, the thesis argues that the rise of globalisation and the end of the Cold War presented the Westphalian or state-centric paradigm of international relations with a Kuhnian paradigm “crisis”. As a result, both the theory and the practice of international relations are in the midst of (what Kuhn calls) a “paradigm shift”. Emerging from this shift is (what is described in this work as) “Access World” and “Denial World” – a particular global configuration of the practice of international relations. Kuhn’s idea of “incommensurability” seems to typify the relationship between the two components of this bifurcated configuration of the international. Both intellectual risk-taking and political courage are required if the ontological struggle raging between “Access World” and “Denial World” is to be settled. This will pave the way for a new paradigm to emerge. Kuhn provides us with the insight that, to achieve this ontological breakthrough, a fundamental change in our vision of the discipline of International Relations, but also of the world of everyday international relations, is required. This entails recasting the study of International Relations as an emancipatory project and by recognising the centrality of human beings in the practice of international relations. Only if this is done, will we be able to arrive at a cosmopolitan political bargain that is appropriate for the 21st century.
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Intraspecific comparison of Phanerochaete chrysosporium strains peroxidase production, pollutant degradation and mycelial differentiation
- Authors: Fraser, Sheena Janet
- Date: 2005
- Subjects: Phanerochaete Pollutants -- Biodegradation Lignin -- Biodegradation Bioremediation Peroxidase Fungi -- Differentiation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3964 , http://hdl.handle.net/10962/d1004023
- Description: The wood-degrading basidiomycete, Phanerochaete chrysosporium, has been studied as a model organism in elucidating the mechanisms and pathways enabling this white-rot fungus to degrade recalcitrant lignin. These same mechanisms are implicated in the mineralisation of environmentally persistent, toxic phenolic chemicals. For this reason, P. chrysosporium has been exploited in a number of environmentally sound technologies, including the degradation of the indigestible lignin component in agricultural waste for the generation of digestible animal feedstocks or high sugar content raw materials for ethanol production; brightening processes in the pulp and paper industry; the detoxification and decolourisation of industrial effluents; and the bioremediation of hazardous waste sites. The improvement of these technologies is dependant on ongoing research involving strain selection, strain development using genetic engineering approaches and process development. Strain improvement using non-recombinant methods is beneficial in that it does not limit the inherent robustness observed amongst natural variants. In this research, through a breeding programme, ten P.chrysosporium sibling strains were screened for variable ligninase activities and pollutant degradation capabilities in order to further describe previously identified differences between these organisms. A conventional stationary liquid culture technique was effectively miniaturised from 10 ml flask cultures to a 96-well microtitre plate format, for the assessment of multigenic traits amongst sibling strains. Using the 96-well microtitre plate method, the relationships between P. chrysosporium growth kinetics, peroxidase production, pollutant sensitivity and pollutant degradation was explored. Significant correlations were primarily associated with P. chrysosporium growth [P < 0.05]. Percentage p-cresol removal and tannic acid tolerance were both correlated with a shorter lag phase in growth [tannic acid: r = 0.7698, P < 0.05; p-cresol: r = 0.7584, P < 0.05] and lower stationary phase biomass levels [tannic acid: r = 0.8177, P < 0.05; p-cresol: r = 0.7803, P < 0.05]. A significant correlation (linear relationship) was also detected between percentage Poly-R478 decolourisation and time of onset of MnP [r = 0.9689, P < 0.001]. No correlation was observed between dye decolourisation, p-cresol degradation, lignin degradation and lignin peroxidase (LiP) or manganese peroxidase (MnP) activities [P > 0.05]. These results imply that differences in the biosynthetic pathways for biomass accumulation in sibling strains play a significant role in the intraspecific variation observed in pollutant sensitivity, pollutant degradation, and enzyme production. Categorical analysis of intraspecific differences was assessed according to four criterions. These included growth, extracellular peroxidase activities, tolerance to toxic pollutants and the biodegradation of model pollutants. Sibling strains showing the most variable responses in three or more of the selective criterion were recommended for further studies. These strains include P. chrysosporium ME446, BS 2.52, BS 13, BS 17, BS 18, and BS 24. Interestingly, BS 2.52 (a dikaryotic strain generating from the crossing of two haploid progeny) showed significantly lower degradation capabilities than the wildtype parent strain ME446. The inherited variability observed between sibling strains is to be further explored through proteome and transcriptome analysis and genetic linkage studies aimed at describing the mechanisms or pathways conferring tolerance to or degradation of environmental pollutants. In examining fewer organisms at this next level, the number of replicates examined can be increased and thus the power of detection of experimental procedures improved, enabling the detection of multigenic traits amongst genetically related organisms. Growth was shown to play a significant role in the intraspecific differences detected in pollutant sensitivity and degradation between sibling strains. Little is known about the mechanism of growth and differentiation, or the role of differentiation in regulating the lignolytic activity in this organism. The membrane gradostat bioreactor and a unique plug-flow membrane bioreactor were evaluated as novel tools with which to further explore the relationship between secondary metabolism, pollutant degradation and biofilm development in sibling strains. High yield MnP production at levels as high as 1478.8 U.l-1 was achieved using a laboratory scale membrane gradostat bioreactor. Furthermore, extensive mycelial differentiation and tissue formation are reported for P. chrysosporium in both the membrane gradostat bioreactor and plug-flow membrane bioreactor. Intraspecific differences in the extent of this differentiation were observed in strains ME446, BS 13, BS 17 and BS 26 cultured using the membrane gradostat bioreactor, highlighting the potential of these techniques as a platform for future strain improvement strategies.
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Introduction [to the book "Thuthula: Heart of the Labyrinth" by Chris Zithulele Mann]
- Authors: Wright, Laurence
- Date: 2005
- Language: English
- Type: Book chapter
- Identifier: vital:7057 , http://hdl.handle.net/10962/d1007419
- Description: There are certain stories, the world over, that stir our hearts and minds to imaginings richer and deeper than the bald facts of history can easily satisfy. Such is the legend of Thuthula, the young Xhosa girl whose beauty and grace won the heart of Ngqika, chief of the Rharhabe Xhosa; the woman who was later married to his uncle Ndlambe, and then taken by Ngqika to become his wife. The events took place in or around the years 1806 and 1807 in what is now the Eastern Cape Province of South Africa. Prior to the central episode treated in the play, legend has it that Thuthula was out collecting firewood one day with her friends when she knelt at a spring to drink. Startled by the sudden appearance of a hunting dog crossing the stream below the spring, she looked up and saw a handsome young hunter chasing behind the dog. She was struck by his charm and good looks. Teasingly, as any young girl might do, she called her friends round her and challenged the young man to choose his favourite from among them. Amid much flirting and laughter, the object of all this girlish attention was pushed into making a choice. Inevitably, given her beauty, his playful decision fell on Thuthula. This was the first meeting of Thuthula, daughter of Mthunzana, with Ngqika, son of Chief Mlawu.
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Investigating call control using MGCP in conjuction with SIP and H.323
- Authors: Jacobs, Ashley
- Date: 2005 , 2005-03-14
- Subjects: Communication -- Technological innovations , Digital telephone systems , Computer networks , Computer network protocols , Internet telephony
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4631 , http://hdl.handle.net/10962/d1006516 , Communication -- Technological innovations , Digital telephone systems , Computer networks , Computer network protocols , Internet telephony
- Description: Telephony used to mean using a telephone to call another telephone on the Public Switched Telephone Network (PSTN), and data networks were used purely to allow computers to communicate. However, with the advent of the Internet, telephony services have been extended to run on data networks. Telephone calls within the IP network are known as Voice over IP. These calls are carried by a number of protocols, with the most popular ones currently being Session Initiation Protocol (SIP) and H.323. Calls can be made from the IP network to the PSTN and vice versa through the use of a gateway. The gateway translates the packets from the IP network to circuits on the PSTN and vice versa to facilitate calls between the two networks. Gateways have evolved and are now split into two entities using the master/slave architecture. The master is an intelligent Media Gateway Controller (MGC) that handles the call control and signalling. The slave is a "dumb" Media Gateway (MG) that handles the translation of the media. The current gateway control protocols in use are Megaco/H.248, MGCP and Skinny. These protocols have proved themselves on the edge of the network. Furthermore, since they communicate with the call signalling VoIP protocols as well as the PSTN, they have to be the lingua franca between the two networks. Within the VoIP network, the numbers of call signalling protocols make it difficult to communicate with each other and to create services. This research investigates the use of Gateway Control Protocols as the lowest common denominator between the call signalling protocols SIP and H.323. More specifically, it uses MGCP to investigate service creation. It also considers the use of MGCP as a protocol translator between SIP and H.323. A service was created using MGCP to allow H.323 endpoints to send Short Message Service (SMS) messages. This service was then extended with minimal effort to SIP endpoints. This service investigated MGCP’s ability to handle call control from the H.323 and SIP endpoints. An MGC was then successfully used to perform as a protocol translator between SIP and H.323.
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Investigation into the biological removal of sulphate from ethanol distillery wastewater using sulphate-reducing prokaryotes
- Authors: Smuts, Lizl
- Date: 2005
- Subjects: Sewage -- Purification -- Biological treatment , Prokaryotes , Sulfates , Distilleries -- Waste disposal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3941 , http://hdl.handle.net/10962/d1004000 , Sewage -- Purification -- Biological treatment , Prokaryotes , Sulfates , Distilleries -- Waste disposal
- Description: Ethanol production wastewater is known to be toxic, and is not easily biodegradable. It also consists of a variety of coloured components adding to the complex composition of this wastewater. Disposal of this wastewater into water courses is not recommended and yet is performed all over the world. Investigation of this wastewater found that there was a high concentration of sulphate which, in the presence of sulphate-reducing prokaryotes can cause sulphide corrosion of cement. The concentration of sulphate in the wastewater was approximately 2770 mg/L. It was also found that the wastewater pH was very low and discharge of the wastewater into the wastewater treatment works caused a negative impact on the overall quality of the final wastewater discharged to sea. It was found using FISH techniques that there were no sulphate-reducing prokaryotes present in the wastewaters but that a sulphate-reducing population existed on the sewer wall. An anaerobic contact process was designed to treat this wastewater targeting sulphate reduction to sulphide, to be converted into elemental sulphur and to increase the wastewater pH. The process did not achieve this aim and only approximately 20-30 % reduction in sulphate from the wastewater was achieved with little to no change in the pH. A 95 % reduction in sulphate concentration was needed in order to reach acceptable discharge limits. Sulphate reduction could not be carried out, even under ideal laboratory conditions. It was found that the barrier causing the digester failure was the high concentration of phenols present in the wastewater (3.3 g/L) together with the production of high concentrations of volatile fatty acids (on average 13 g acetic/L). These two components are known to cause digester failure, especially phenols, and phenols are usually only degraded by fungal species. It was concluded that the wastewater itself was not amenable to this method of biological treatment.
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Isolation and characterization of a novel thermostable and catalytically efficient laccase from Peniophora sp. strain UD4
- Authors: Jordaan, Justin
- Date: 2005
- Subjects: Enzymes Enzymes -- Industrial applications Peniophora Laccase
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3970 , http://hdl.handle.net/10962/d1004029
- Description: Enzymes are becoming an effective tool in industrial processes, from crude applications such as bioremediation to fine processes such as chirally selective biocatalysis. The ligninolytic enzymes have recently received considerable attention for industrial application due to both their broad substrate range and their ability to degrade the most recalcitrant natural polymer, lignin. This group of enzymes was therefore identified as the target group for this study. Improved enzyme properties are constantly being sought to enhance the range of applications for enzymes. Biodiversity provides a wide variety of enzymes. Several researchers have concentrated on extremophiles as their primary source of superior enzymes, consequently neglecting temperate environments in their search for these enzymes. The relatively neglected fungal biodiversity of South Africa provided an opportunity to test the hypothesis that potentially important industrial enzymes with unusual properties could be isolated from mesophilic basidiomycetous fungi. Subsequent screening of Eastern Cape biodiversity for thermostable ligninolytic enzymes from basidiomycetes resulted in the isolation of a novel laccase enzyme from a basidiomycetous species. This fungus was identified as Peniophora sp. UD4 by phylogenetic analysis of rDNA ITS sequences. Initial studies indicated a superior optimum temperature of 70°C and thermostability, indicated by no loss in activity at 60°C over nine hours. Further characterization of the laccase revealed a broader than usual substrate range through its unusual ability to oxidatively couple DMAB and MBTH. The laccase also exhibited a broad pH oxidation range for ABTS (pH 2 – 6.8), and a relatively high affinity (K_m_ = 0.0123 mM) and catalytic efficiency (63 252 mM^(-1)^s^(-1)^) for ABTS as a substrate. The laccase activity from Peniophora sp. UD4 was shown to be comprised of three isozymes with a molecular weight of 62 kDa and pI’s of 6.33, 6.45 and 6.50. Investigation of the nutrient and physical factors affecting ligninolytic enzyme production and growth of Peniophora sp. UD4 indicated that the wild-type organism was unsuitable for large scale production of the thermostable laccase due to the low levels of laccase production. The thermostable laccase was applied to defouling of ultrafiltration membranes, bioremediation of industrial waste streams, biocatalysis, and biosensor technology as potential applications. Application of the Peniophora sp. UD4 laccase to defouling of membranes used for ultrafiltration of brown water showed large flux recoveries of 31, 21 and 21% after the first three defouling recycles respectively, compared to 3% for the control without immobilized enzyme. The novel laccase showed potential for the bioremediation of industrial waste streams, the most successful being that of bleach plant effluent, where a reduction of 66% of the phenolic load was achieved. Application of the novel laccase to biocatalytic oxidation of ferulic acid and (±)-α-pinene showed higher product yield as compared to oxidation of these compounds by Trametes versicolor laccase in mediated and non-mediated systems. The major products of (±)-α-pinene oxidation were identified as verbenol and trans-sorberol. The Peniophora sp. UD4 laccase was successfully applied to biosensor technology, which benchmarked significantly better than Trametes versicolor laccase for the detection of 4-chlorophenol. The biosensor developed with laccase from UD4 by covalent binding to a glassy carbon electrode exhibited the best combination of sensitivity and stability. This thesis shows that a laccase with superior properties was obtained from a mesophilic South African basidiomycete. The catalytic properties displayed by the novel laccase from Peniophora sp. UD4 all contribute to the increased industrial applicability of laccases, and may be the most industrially feasible enzyme of its class isolated to date.
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Isolation, purification and characterization of inulin and fructooligosaccharides from chicorium intybus and inulinase from aspergillus niger
- Authors: Mavumengwana, Vuyo Bhongelethu
- Date: 2005
- Subjects: Aspergillus , Inulin , Chicory -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3954 , http://hdl.handle.net/10962/d1004013 , Aspergillus , Inulin , Chicory -- South Africa
- Description: Inulin is a non-digestible carbohydrate fructan polymer consisting mainly of β (1→2) fructosyl fructose links. Enzymatic hydrolysis of inulin by inulinase results in the production of low D.P (degree of polymerization) oligosaccharides also called fructooligosaccharides(FOS). Isolation of inulin from chicory root (Chicorium intybus) was achieved by first, extraction using deionized water (600C), followed by carbonation (0.1 M Ca(OH)2 and CO2 gas). This was filtered in order to remove the non sugars, thereafter, treated successfully with polyamide 6 powder. A cation exchanger and an anion exchanger were used to further exclude other components such as tannins and pigments. The extracted inulin was quantified using the Somogyi-Nelson colourimetric assay. Chicory root (207 g, 30 % being water) yielded 30 g of the raw extract. A 100 mg of the raw extract was assayed and found to contain 11 % yield of inulin which was 80.2 % in purity and 4 % free fructose. Analysis of the crude and purified inulin extracts on the MALDI TOF spectrometry showed the samples to have a DP of 2 to 22 and 2 to 27 respectively. Maximum inulinase production from Aspergillus niger grown on inulin was observed after 60 hours. The enzyme activity was found to be 1.168 U/ml with a temperature and pH optimum of 30 °C and 7.7 respectively. The enzyme proved to be unstable as it progressively lost its total activity during attempts at purification.
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Language is culture:
- Authors: Malila, Vanessa
- Date: 2005
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159256 , vital:40281 , https://hdl.handle.net/10520/EJC146402
- Description: Many of us think that English dominates the web pages we surf each day. Indeed, until recently English was the predominant language for publishing online, but things are slowly changing and the presence of linguistic diversity on the Internet is starting to become a reality in the global village. The question, however, remains: how many African languages are represented in that diversity?.
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Late glacial and holocene palaeoclimatology of the Drakensberg of the Eastern Cape, South Africa
- Authors: Lewis, Colin A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6692 , http://hdl.handle.net/10962/d1006727
- Description: Eight climatic events during the Holocene are evidenced in the East Cape Drakensberg by fluvial, archaeological and palynological deposits. Flood plain deposition under relatively moist conditions occurred in the Early Holocene, before ca. 7000 BP. Semi-arid conditions with limited fluvial activity dominated the Mid Holocene until ca. 3200 BP. Alternating flood plain erosion and deposition occurred in the Late Holocene. Four climatic events, for which there is palynological and limited archaeological evidence, have been identified in the Late Glacial.
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