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GPU Accelerated protocol analysis for large and long-term traffic traces

- Nottingham, Alastair Timothy

Authors: Nottingham, Alastair Timothy
Date: 2016
Language: English
Type: Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/910 , vital:20002
Description: This thesis describes the design and implementation of GPF+, a complete general packet classification system developed using Nvidia CUDA for Compute Capability 3.5+ GPUs. This system was developed with the aim of accelerating the analysis of arbitrary network protocols within network traffic traces using inexpensive, massively parallel commodity hardware. GPF+ and its supporting components are specifically intended to support the processing of large, long-term network packet traces such as those produced by network telescopes, which are currently difficult and time consuming to analyse. The GPF+ classifier is based on prior research in the field, which produced a prototype classifier called GPF, targeted at Compute Capability 1.3 GPUs. GPF+ greatly extends the GPF model, improving runtime flexibility and scalability, whilst maintaining high execution efficiency. GPF+ incorporates a compact, lightweight registerbased state machine that supports massively-parallel, multi-match filter predicate evaluation, as well as efficient arbitrary field extraction. GPF+ tracks packet composition during execution, and adjusts processing at runtime to avoid redundant memory transactions and unnecessary computation through warp-voting. GPF+ additionally incorporates a 128-bit in-thread cache, accelerated through register shuffling, to accelerate access to packet data in slow GPU global memory. GPF+ uses a high-level DSL to simplify protocol and filter creation, whilst better facilitating protocol reuse. The system is supported by a pipeline of multi-threaded high-performance host components, which communicate asynchronously through 0MQ messaging middleware to buffer, index, and dispatch packet data on the host system. The system was evaluated using high-end Kepler (Nvidia GTX Titan) and entry level Maxwell (Nvidia GTX 750) GPUs. The results of this evaluation showed high system performance, limited only by device side IO (600MBps) in all tests. GPF+ maintained high occupancy and device utilisation in all tests, without significant serialisation, and showed improved scaling to more complex filter sets. Results were used to visualise captures of up to 160 GB in seconds, and to extract and pre-filter captures small enough to be easily analysed in applications such as Wireshark.
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Date Issued: 2016

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Grade 12 learners' perceptions of the effect of urban agriculture on life satisfaction in Duncan Village

- Beni, Ntombomzi Octavia

Authors: Beni, Ntombomzi Octavia
Date: 2016
Subjects: Urban agriculture -- South Africa -- Eastern Cape Agricultural education
Language: English
Type: Thesis , Masters , MEd
Identifier: http://hdl.handle.net/10353/17861 , vital:41461
Description: The importance of agricultural sciences in the school curriculum all over the world cannot be over-emphasized. It includes an alternative source of fresh produce, improved life satisfaction and a way to preserve cultural identity and traditions. This research study seeks to investigate the perception of Grade 12 learners on the effects of urban agriculture on life satisfaction in Duncan Village. The study adopts a descriptive survey design to elicit information from the respondents on their perceptions on the effects of urban agriculture on life satisfaction. A validated structured questionnaire whose reliability co-efficient is 0.81 was used to collect information. The simple random sampling technique was used to select 78 (seventy-eight) Grade 12 learners. The study reveals among others some components of life satisfaction as a result of urban agriculture. These components are; nutrition, self-employment, food security and poverty eradication and they have positive effects on life satisfaction of the respondents. The study recommends that the South Africa Government should make agriculture education as a compulsory subject for grade 10 and 11 learners in rural areas. This will enable them to develop entrepreneurial skills and self-reliance mentality before they finish their secondary school careers. Similarly, the practical components of this subject should constitute 50percent if not more from the overall marks. Realisation of this idea will alleviate, to some extent burden of unemployment and food scarcity as school leavers will be able to implement right away agricultural skills already acquired.
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Date Issued: 2016

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Gradient high performance liquid chromatographic method for the simultaneous analysis of efavirenz, emtricitabine and tenofovir

- Koekemoer, Sonya Mariana

Authors: Koekemoer, Sonya Mariana
Date: 2016
Language: English
Type: text , Thesis , Masters , MPharm
Identifier: http://hdl.handle.net/10962/54679 , vital:26599
Description: In 2014, approximately 6.8 million people in South Africa were HIV-positive, and the majority of those affected are aged 15 or older. A fixed-dose combination (FDC) antiretroviral (ARV) dosage form containing one non-nucleotide reverse transcriptase inhibitor (efavirenz) and two nucleotide reverse transcriptase inhibitors (emtricitabine and tenofovir) was licensed in South Africa in April 2013. New consolidated guidelines for HIV management and prevention of mother to child transmission (PMTCT) were published by the South African Department of Health in December 2014 and the FDC is now the recommended first-line treatment for HIV-positive patients. According to these guidelines all such people aged 15 and older, and weighing more than 40 kg, with a CD4 count of ≤ 500/ μl will be eligible for antiretroviral therapy (ART) using the FDC. In addition every pregnant and breastfeeding woman is eligible for lifelong ART regardless of CD4 count and EFV can be used as first-line treatment for pregnant women regardless of the length of gestation state of the pregnancy at that time. The use of this simplified regime is likely to promote much needed and improved adherence to therapy. An investigation into the development of a stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method for the simultaneous quantitation of EFV, FTC and TNF was undertaken. Isocratic HPLC analysis was found to be unsuitable due to the highly polar FTC molecule eluting in the void. Therefore a gradient HPLC method was developed and validated. The method was validated according to the International Conference on Harmonisation, now known as International Council for Harmonization (ICH). Correlation coefficients > 0.999 were obtained for each assessment of linearity and FTC, TNF and EFV are linear in the range 0.4-40 μg/ml, 0.6-60 μg/ml and 1.2-120 μg/ml. The equation of the best-fit least squares regression lines for FTC, TNF and EFV were y = 0.0191x+0.0007, y = 0.0163x+0.0116 and y = 0.01x+0.016, respectively. The method is accurate as the y-intercept was < 2% of the detector response for all ARV, and the method is precise in terms of intra- and inter-assay precision as all % RSD < 2%. The stability-indicating nature of the method was demonstrated under acidic, alkaline and oxidative stress in addition to UV exposure and elevated temperatures, and the individual chromatograms were overlaid using Empower® 3 Software to establish whether there was interference with the peaks of interest. The forced degradation studies demonstrated the selectivity of the method for the ARV compounds. The method was applied to assay and in vitro dissolution studies of commercially available tablets. The amount of each active ingredient released from Atripla® was determined and compared to the amount of each drug released from Aspen Efavirenz® and Truvada® (a combination of FTC and TNF). The percent FTC released from Atripla® and Truvada® was similar based on the acceptance criteria for immediate-release BCS class 1 compounds. Statistical analysis was undertaken to compare the dissolution profiles of FTC, TNF and EFV. The percent of these compounds released in these studies indicate that bioequivalence testing would be required to declare these products interchangeable. The validated RP-HPLC and in vitro dissolution test method are suitable for routine quality control testing of solid oral dosage forms containing EFV, FTC and TNF, and as the dissolution method can discriminate between different formulations of the same molecule, these tools can also be used for analysis during formulation development studies. The method is not suitable for the analysis of the ARV plasma due to lack of sensitivity and an inability to quantitate the compounds at the required concentration levels. The use of HPLC with mass spectroscopy for quantitation would enhance the sensitivity of the method and may eliminate the quantitation of the molecules in the presence of interference that was observed when using UV detection. Fixed dose combination tablets are convenient for patient therapy and it is likely that in the future more molecules will be formulated into such dosage forms. However formulations such as these can pose significant difficulties when developing and using analytical methods for the quantitation of all compounds in the dosage form at the same time, in particular when the compounds have vastly different physico-chemical properties that impact the quality of a separation and therefore the analysis. Therefore when embarking on the development of FDC product cognisance of the difficulties of developing single methods for the analyses is required and approaches to overcome these difficulties should be considered.
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Date Issued: 2016

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Graduate job search activity in Zambia: a social capital analysis

- Nsenduluka, Mukupa

Authors: Nsenduluka, Mukupa
Date: 2016
Subjects: Social capital (Sociology) -- Zambia Unemployment -- Zambia , College graduates -- Employment -- Zambia
Language: English
Type: Thesis , Masters , MA
Identifier: http://hdl.handle.net/10948/12917 , vital:27134
Description: There is much to be said about the use of social capital in the job search patterns of graduates, however, little is researched on the use of social capital as a job search strategy. Despite the years of research that acknowledges the critical role social capital plays in determining job search outcomes, little to no research has been done to specifically understand the different ways in which graduates utilize their social capital (family, friends and acquaintances) to look for work. Human capital theory posits that education is the greatest determinant of employment in a labour market system that that awards educational credentials with occupational attainment. However, the reality is that a large number of Zambian graduates are jobless despite being educated. This study, therefore seeks to analyse the high levels of graduate unemployment from lternative theories of social capital and the job search. Knowing the different ways social capital expresses itself in graduate job search patterns provides possible solutions and a different perspective to addressing the high levels of graduate unemployment in Zambia. This study adopted a qualitative case study research design and made use of the snow ball sampling approach. Fifteen semistructured interviews were conducted and findings and emerging themes analysed in response to the central question, “how does social capital express itself in graduate job search patterns in Lusaka, Zambia?”. Through extensive thematic analyses, the researcher finds that there are eight ways in which graduates utilize their social capital to look for work and overcome challenges of the job search. This demonstrates that social capital can be a useful and beneficial job search strategy to adopt in a labour market system where educational credentials alone do not guarantee graduates successful job search outcomes.
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Date Issued: 2016

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Graphene quantum dots functionalized with 4-amino-2, 2, 6, 6-tetramethylpiperidine-N-oxide as fluorescence “turn-on” nanosensors

- Achadu, Ojodomo J, Britton, Jonathan, Nyokong, Tebello

Authors: Achadu, Ojodomo J , Britton, Jonathan , Nyokong, Tebello
Date: 2016
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/239854 , vital:50773 , xlink:href="https://doi.org/10.1007/s10895-016-1916-y"
Description: In this study, we report on the fabrication of simple and rapid graphene quantum dots (GQDs)-based fluorescence “turn-ON” nanoprobes for sensitive and selective detection of ascorbic acid (AA). Pristine GQDs and S and N co-doped-GQDs (SN-GQDs) were functionalized with 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide (4-amino-TEMPO, a nitroxide free radical). The nitroxide free radicals efficiently quenched the fluorescence of the GQDs and upon interaction of the nanoconjugates with ascorbic acid, the quenched fluorescence was restored. The linear ranges recorded were 0.5–5.7 μM and 0.1–5.5 μM for GQDs-4-amino-TEMPO and SN-GQDs-4amino-TEMPO nanoprobes, respectively. Limits of detection were found to be 60 nM and 84 nM for SN-GQDS-4-amino-TEMPO and GQDs-4-amino-TEMPO for AA detection, respectively. This novel fluorescence “turn-ON” technique showed to be highly rapid and selective towards AA detection.
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Date Issued: 2016

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Hate speech as a limitation to freedom of expression

- Botha, Joanna Catherine

Authors: Botha, Joanna Catherine
Date: 2016
Subjects: Freedom of speech -- South Africa , Hate speech -- South Africa , Civil rights -- South Africa
Language: English
Type: Thesis , Doctoral , LLD
Identifier: http://hdl.handle.net/10948/9054 , vital:26460
Description: Hate speech in South Africa creates a tension between the right to freedom of expression and the rights to human dignity and equality. The challenge is to achieve a balance between these competing rights in the context of the divisive past and the transformative constitutional ideal, in which reconciliation and respect for group difference are promoted. Freedom of expression, an individual right, must be construed in light of its underlying values, but regard must also be given to communitarian interests. The constitutional standard draws the initial line. The advocacy of hatred on four grounds and which constitutes incitement to cause harm is not constitutionally protected speech. Such speech undermines nation building, causes acrimony, and is not tolerated in the egalitarian society envisaged by the Constitution. The thesis formulates a principled legislative hate speech framework for South Africa at both human rights and criminal levels within the parameters of the constitutional mandate, as guided by the standard for hate speech restrictions in international law, and the Canadian regulatory model. An essential premise is that regulation requires a multi-faceted balancing enquiry. A holistic approach is proposed where factors such as respect for the dignity of the victims, autonomy for speakers, listeners and the wider community; the causal link between hate speech and hatred in a community; and the desire to achieve a diverse and harmonious society; amongst others, are considered. Failure to regulate hate speech constructively endorses hatemongers and promotes damaging speech at the expense of vulnerable groups. Regulation ensures that law sets the normative benchmark, affirms the protection of vulnerable groups within the social fabric and upholds social cohesion, inclusiveness and the equal citizenship of all individuals in society. The thesis contains a proposal for the enactment of legislation creating a self-standing hate speech crime for the advocacy of extreme hatred, shaped in accordance with international requirements and comparative foreign law, and structured in light of the distinction between hate crime and hate speech. The existing legal framework is unable to provide consistent and fitting redress for the severe harm caused by such speech, namely the fostering of an environment in which the stigmatisation of groups is promoted, their exclusion from society justified and intervention is needed to remedy the escalated levels of hatred and violence between different groups in society. PEPUDA, a remedial statute aimed at promoting transformation and substantive equality, is valuable, but its speech prohibitions are broad and imprecise. Consequently, their effectiveness is compromised and their constitutionality questioned. The thesis proposes recommendations for amendments to sections 7(a), 10(1) and 12 of PEPUDA. The aim is to ensure compliance with the international standard and to foster the optimal regulation of hate speech and other forms of damaging speech, including derogatory racial epithets, which undermine human dignity and equality and threaten national unity. It is intended for the two systems to complement one another and to create a legal framework aimed at addressing hate speech constructively and in context, promoting tolerance, respect for difference, reconciliation and transformation.
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Date Issued: 2016

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HealthMessenger: an e-Health service to support ICT deployments in poor areas

- Gremu, Chikumbutso, Terzoli, Alfredo, Tsietsi, Mosiuoa

Authors: Gremu, Chikumbutso , Terzoli, Alfredo , Tsietsi, Mosiuoa
Date: 2016
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/430609 , vital:72703 , 10.1109/ISTAFRICA.2016.7530632
Description: Development and implementation of appropriate e-services as well as revenue generation are key to deploying and sustaining ICT installa-tions in poor areas in developing countries. The area of e-Health is a promising area for e-Services that are important to populations in poor areas and health service organisations that are already spending mon-ey on different health initiatives in these areas. This paper discusses an e-Health service that facilitates dissemination of health information to people living in poor areas and that is subsequently used to generate revenue to support deployment and development of ICT in the areas. The tool was developed within the context of the Siyakhula Living Lab (SLL), a multi-stakeholder operation that promotes ICT for Development in the Eastern Cape Province of South Africa. Creation of health con-tent for the e-health service and its subsequent consumption happen in two different environments from a technological and social point of view. To enable this to happen, the e-service comprises two component applications that run in a peer-to-peer fashion. The component that is used to disseminate content for end-user consumption is called the HealthMessenger. The HealthMessenger is hosted on an environment called TeleWeaver, an application integration platform developed within the SLL to host software applications targeting people living in poor ar-eas. The platform is customised to support services with a revenue generation component.
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Date Issued: 2016

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Hearing the voice of rural women regarding personal development issues

- Ntloko, Balisa Mirriam

Authors: Ntloko, Balisa Mirriam
Date: 2016
Subjects: Women in rural development -- South Africa -- Eastern Cape Women's rights -- South Africa , Rural poor -- South Africa -- Eastern Cape
Language: English
Type: Thesis , Masters , MA
Identifier: http://hdl.handle.net/10948/12736 , vital:27116
Description: Some rural communities in South Africa suffer from the results of inequity and disempowerment. It is especially black females who are affected in this regard. A number of factors contribute to the oppression of female voices in their rural communities. In this study the voice is considered the right and freedom of speech for women to express their opinions in order to influence others. Both the national government and civil society fervently push for the placement of women and children empowerment onto the development agenda. Yet, one still notes with concern that in reality, it seems to be mostly men who fully enjoy freedom of speech, senior employment and decision making powers in South Africa. Thus, it remains evident that not enough has been done to redress gender inequities,especially in South African rural communities. Focussing on one rural community situated in the outskirts of the Eastern Cape (former Transkei), this research undertook to determine the various ways in which rural women may have their voice heard in their immediate communities, particularly pertaining to personal development issues. Community members, who were identified through a purposive sampling method, shared their perceptions on the research topic.Through the research, it has become clear that in order to overcome female silence, the communal role of women needs to be broadened beyond the scope of traditionally gendered activities such as the carrying out of house work/chores such as cooking or childrearing. Furthermore, women must be knowledgeable about their basic human rights and responsibilities; their education in this regard should be made a national priority. It has also become evident that in order to overcome female voices remaining silent, women should begin to take greater personal responsibility over their reproductive health.Practical recommendations to ddress each framed theme have been presented.
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Date Issued: 2016

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Hearing things

- Claassen, José

Authors: Claassen, José
Date: 2016
Language: English
Type: Thesis , Masters , MA
Identifier: vital:6019 , http://hdl.handle.net/10962/d1021243
Description: William Carlos Williams wrote: "It isn't what the poet says that counts as a work of art, it's what he makes, with such intensity of purpose that it lives with an intrinsic movement of its own to verify its authenticity." I would like to think that my poems only borrow life from my pen, taking on an identity and music of their own with the help of some ‘making’ on my part. My poems embrace a continuum of human experience from the intrapersonal to the societal. Using imagistic and cinematic forms, they preserve the vitality of their sources, from the music of cityscapes, to the texture of emotions, to the narratives of particular characters.
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Date Issued: 2016

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Heat accumulation and development rate of massed maggots of the sheep blowfly, Lucilia cuprina (Diptera: Calliphoridae)

- Kotzé, Zanthé, Villet, Martin H, Weldon, Christopher W

Authors: Kotzé, Zanthé , Villet, Martin H , Weldon, Christopher W
Date: 2016
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/442168 , vital:73964 , https://doi.org/10.1016/j.jinsphys.2016.09.009
Description: Blowfly larvae aggregate on exposed carcasses and corpses and pass through three instars before wandering from the carcass and pupating. The developmental landmarks in this process can be used by forensic entomologists to estimate the time since the insects colonised the carcass, which sets a minimum post mortem interval. Large aggregations of feeding larvae generate a microclimate with temperatures up to 15 °C above ambient conditions, which may accelerate larval development and affect forensic estimates of post-mortem intervals. This study investigated the effects of heat accumulated by maggot masses of Lucilia cuprina at aggregations of 20, 50 and 100 larvae, each at incubation temperatures of 18 °C, 24 °C and 30 °C, using body length and life stage as developmental indicators. Aggregation temperatures reached up to 18.7 °C above ambient temperature, with significant effects of both size and temperature of the aggregation on the development time of its larvae. Survivorship was highest for all life stages at 24 °C, which is near the developmental optimum of L. cuprina. The results of this study provide a broadly applicable method of quantifying heat accumulation by aggregations of a wide range of species of forensic importance, and the results obtained from such studies will demonstrate that ambient temperature cannot be considered the only source of heat that blowfly larvae experience when they develop on a carcass. Neglect of temperatures within larval aggregations will result in an overestimation of post-mortem intervals and thus have far-reaching medicolegal consequences.
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Date Issued: 2016

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Heat shock protein inhibitors: success stories

- McAlpine, Shelli R, Edkins, Adrienne L

Authors: McAlpine, Shelli R , Edkins, Adrienne L
Date: 2016
Language: English
Type: text , book
Identifier: http://hdl.handle.net/10962/66359 , vital:28940 , https://doi.org/10.1007/978-3-319-32607-8
Description: publisher version , Introduction: Medicinal chemistry is both science and art. The science of medicinal chemistry offers mankind one of its best hopes for improving the quality of life. The art of medicinal chemistry continues to challenge its practitioners with the need for both intuition and experience to discover new drugs. Hence sharing the experience of drug research is uniquely beneficial to the field of medicinal chemistry. Drug research requires interdisciplinary team-work at the interface between chemistry, biology and medicine. Therefore, the topic-related series Topics in Medicinal Chemistry covers all relevant aspects of drug research, e.g. pathobiochemistry of diseases, identification and validation of (emerging) drug targets, structural biology, drugability of targets, drug design approaches, chemogenomics, synthetic chemistry including combinatorial methods, bioorganic chemistry, natural compounds, high-throughput screening, pharmacological in vitro and in vivo investigations, drug-receptor interactions on the molecular level, structure-activity relationships, drug absorption, distribution, metabolism, elimination, toxicology and pharmacogenomics. In general, special volumes are edited by well known guest editors. , This work is based on the research supported by the South African Research Chairs Initiative of the Department of Science and Technology and National Research Foundation of South Africa (Grant No 98566), the Cancer Association of South Africa (CANSA), Medical Research Council South Africa (MRC-SA) and Rhodes University. The views expressed are those of the authors and should not be attributed to the DST, NRF, CANSA, MRC-SA or Rhodes University. We apologize if we have inadvertently missed any important contributions to the field.
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Date Issued: 2016

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Heavy mineral characterization and provenance interpretation of the Ecca Group of geological formations in Eastern Cape Province, South Africa

- Sinuka, Sikhulule

Authors: Sinuka, Sikhulule
Date: 2016
Subjects: Minerals -- South Africa -- Eastern Cape -- Classification Geology -- South Africa -- Eastern Cape Formations (Geology) -- South Africa -- Eastern Cape
Language: English
Type: Thesis , Masters , MSc
Identifier: http://hdl.handle.net/10353/2911 , vital:28125
Description: The aim of the research focuses on characterizing heavy mineral assemblages and interpretation of the provenance of the Ecca Group of in the Eastern Cape Province, South Africa. In South Africa, the Ecca Group outcrops extensively in the Main Karoo Basin. Mudstone, siltstone, sandstone, minor conglomerate and coal are the major constituent lithologies within the group. For descriptive purposes, the Ecca is categorized into three different geographical areas: the southern area, the western and northwestern area and the northeastern area. Six of the sixteen geological formations, namely the Prince Albert, Whitehill, Collingham, Ripon, Fort Brown, Waterford and Koonap Formations are present in the study area and are best exposed in road cuttings. For purposes of comparison, the underlying Witteberg Group, the Dwyka (which has Formation status here), and the overlying Koonap Formation of the Beaufort Group, are included in the study. This study is motivated by the relatively little information that is available on the heavy minerals of the Ecca Group, and that research of this nature had not been undertaken in the study area before. Another contributing motivation was to determine whether heavy mineral assemblages could be used to identify formations of the Ecca Group and for correlating between different localities in accordance with studies done elsewhere. Additionally, diagnostic heavy mineral assemblages could aid with stratigraphic selection of future boreholes in the Ecca Group. Heavy minerals are natural provenance tracers because of their stable nature and hydrodynamic behaviour. They are both non-opaque and opaque, with apatite, epidote, garnet, rutile, staurolite, tourmaline and zircon being good examples of non-opaque grains while ilmenite and magnetite are the most common opaques. Heavies are either derived from stable minor accessory minerals or from abundant but unstable mafic components of the host rock. They are very useful in interpreting the provenance due to the fact that some minerals are diagnostic of certain source rocks. However, sediments are exposed to several factors (conditions) such as weathering, erosion, breakage due to abrasion, mixing and recycling during transportation from the source to the depositional area. This implies that there are parameters other than the parent lithology that determine their final composition.
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Date Issued: 2016

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Herman Charles Bosman: A man of profound contradictions

- Leff, Carol W

Authors: Leff, Carol W
Date: 2016
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/458524 , vital:75751 , https://hdl.handle.net/10520/EJC190700
Description: Herman Charles Bosman is best known for his humorous short stories with signature twist endings. He is less well known for his essays and journalistic writing, which illustrate another side of this enigmatic man. This essay focuses on the paradox that Bosman was (and continues to be) and aims to respond to the following questions: How are we to understand the identity of Herman Charles Bosman? How did he contribute towards an understanding of language and culture in South Africa during his lifetime? Was Bosman consistent in expressing his views through his literary works, or is there evidence of incongruity? These complexities are explored by, first, paying close attention to various biographies on Bosman. His hybrid identity is then illustrated by providing examples of the many pseudonyms he employed over a period of time. This is followed by discussion of several of Bosman's non-fiction pieces, highlighting how contradictions are apparent in his beliefs and philosophy. The essay concludes that Bosman vacillated in both his writing and his beliefs, and was indeed a man of contradictions.
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Date Issued: 2016

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Heterogeneity in virulence relationships between Cryptophlebia leucotreta granulovirus isolates and geographically distinct host populations: Lessons from codling moth resistance to CpGV-M

- Opoku-Debrah, John K, Hill, Martin P, Knox, Caroline M, Moore, Sean D

Authors: Opoku-Debrah, John K , Hill, Martin P , Knox, Caroline M , Moore, Sean D
Date: 2016
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/417998 , vital:71500 , xlink:href="https://doi.org/10.1007/s10526-016-9728-1"
Description: In South Africa, the baculovirus Cryptophlebia leucotreta granulovirus (CrleGV) is used to control the citrus pest Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae). However, the risk associated with continuous application of a single active ingredient is resistance. In order to manage resistance should it occur in field populations of T. leucotreta in South Africa, five new CrleGV genotypes from geographically distinct insect populations which were shown to exhibit some degree of phenotypic variation were recovered and genetically characterized. In droplet bioassays using seven CrleGV isolates against five T. leucotreta populations, some isolates were found to show higher virulence to some host populations than others. There were marked differences in the LD50 values of isolates and the number of occlusion bodies required per larva ranged between 0.79 and 3.12. The significance of these findings with respect to the application of CrleGV biopesticides and the management of resistance is discussed.
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Date Issued: 2016

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Higher order modulation formats for high speed optical communication systems with digital signal processing aided receiver

- Chabata, Tichakunda Valentine

Authors: Chabata, Tichakunda Valentine
Date: 2016
Subjects: Optical communications , Modulation (Electronics) , Signal processing
Language: English
Type: Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10948/4775 , vital:20677
Description: The drastic increase in the number of internet users and the general convergence of all other communication systems into an optical system have brought a sharp rise in demand for bandwidth and calls for high capacity transmission networks. Large unamplified transmission reach is another contributor in reducing deployment costs of an optical communication system. Spectrally efficient modulation formats are suggested as a solution to overcome the problems associated with limited channels and bandwidth of dense wavelength division multiplexing (DWDM) optical communication systems. Higher order modulation formats which are considered to be spectrally efficient and can increase the transmission capacity by transmitting more information in the amplitude, phase, polarization or a combination of all was studied. Different detection technologies are to be implemented to suit a particular higher order modulation format. In this research multilevel modulation formats, different detection technologies and a digital signal processing aided receiver were studied in a practical optical transmission system. The work in this thesis started with the implementation of the traditional amplitude shift keying (ASK) modulation and a differential phase shift keying (DPSK) modulation systems as they form the basic building block in the design of higher order modulation formats. Results obtained from using virtual photonics instruments (VPI)simulation software, receiver sensitivity for 10Gbpsnon-return-to-zero (NRZ), amplitude phase shift keying (ASK) and DPSK signals were measured to be -22.7 dBm and -22.0 dBm respectively. Performance comparison for the two modulation formats were done over different transmission distances. ASK also known as On-Off keying (OOK) performed better for shorter lengths whereas DPSK performed better for longer lengths of up to90km.Experimental results on a 10 Gbps NRZ- ASK signal gave a receiver sensitivity of -21.1 dBm from digital signal processing (DSP) aided receiver against -19.8 dBm from the commercial bit error ratio tester (BERT) yielding a small difference of 1.3 dB hence validating the reliability and accuracy of the digital signal processing (DSP) assisted receiver. Traditional direct detection scheme and coherent detection scheme performances were evaluated again on a 10 Gbps NRZ ASK signal. Coherent detection that can achieve a large unamplified transmission reach and has a higher passive optical splitting ratio was first evaluated using the VPI simulation software. Simulation results gave a receiver sensitivity of -30.4 dBm forcoherent detection and -18.3 dBm for direct detection, yielding a gain in receiver sensitivity of 12.1 dB. The complex coherently detected signal, from the experimental setup gave a receiver sensitivity of -20.6 dBm with a gain in receiver sensitivity of 3.5 dBm with respect to direct detection. A multilevel pulse amplitude modulation (4-PAM) that doubles the data rate per channel from10 Gbps to 20 Gbps by transmitting more information in the amplitude of the carrier signal was implemented. This was achieved by modulating the optical amplitude with an electrical four level amplitude shift keyed (ASK) signal. A receiver consisting of a single photodiode, three decision circuits and a decoding logic circuit was used to receive and extract the original transmitted data. A DSP aided receiver was used to evaluate the link performance. A receiver sensitivity of -12.8 dBm is attained with a dispersion penalty of about 7.2 dB after transmission through 25 km of G.652 fibre.
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Date Issued: 2016

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Historical perspectives and future directions for access to land, water and related ecosystem services in the Lower Sundays River Valley, South Africa: implications for human well being

- Chadzingwa, Karabo

Authors: Chadzingwa, Karabo
Date: 2016
Language: English
Type: Thesis , Masters , MSc
Identifier: http://hdl.handle.net/10962/442 , vital:19959
Description: The legacy of South Africa’s history has facilitated unequal access to land and water resources. In the Lower Sundays River Valley (LSRV), a predominantly commercial farming area, differential access to land and water has impacted aspects of ecosystem service access and human well‐being for disenfranchised families over time. Despite the social, political and economic reform efforts in the past two decades, severe inertia towards efforts attempting to increase equitable access to land and water has been experienced. As a result, communities have mobilized and claimed their land from the government through the land restitution process. Based on a mixed‐methods approach, this research explores the ways in which access to land and water over time has influenced current levels of human well‐being among disenfranchised families. Provisioning and cultural ecosystem services were identified as key areas of loss as a result of forced evictions from land. Freedom of choice was a central and cross‐cutting theme regarding the ability to change levels of human well‐being. Although the loss of ecosystem services associated with land and water had an impact on households, the ecosystem services which are regarded as fundamental to human well‐being do not seem to have been lost. The study recommends the wide use of freedom of choice as an indicator for well‐being in the LSRV, as well as a consideration of subjective, objective and psychological measures of well‐being with regards to natural resources and ecosystem services access. Key agents in fostering desirable pathways toward equity and sustainability in the LSRV are identified with stakeholders as private businesses; inclusive governance; empowered and skilled individuals, as well as NGOs.
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Date Issued: 2016

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How content analysis may complement and extend the insights of discourse analysis: An example of research on constructions of abortion in South African newspapers 1978–2005

- Feltham-King, Tracey, Macleod, Catriona I

Authors: Feltham-King, Tracey , Macleod, Catriona I
Date: 2016
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/446258 , vital:74485 , xlink:href="https://doi.org/10.1177/1609406915624575"
Description: Although discourse analysis is a well-established qualitative research methodology, little attention has been paid to how discourse analysis may be enhanced through careful supplementation with the quantification allowed in content analysis. In this article, we report on a research study that involved the use of both Foucauldian discourse analysis (FDA) and directed content analysis based on social constructionist theory and our qualitative research findings. The research focused on the discourses deployed, and the ways in which women were discursively positioned, in relation to abortion in 300 newspaper articles, published in 25 national and regional South African newspapers over 28 years, from 1978 to 2005. While the FDA was able to illuminate the constitutive network of power relations constructing women as subjects of a particular kind, questions emerged that were beyond the scope of the FDA. These questions concerned understanding the relative weightings of various discourses and tracing historical changes in the deployment of these discourses. In this article, we show how the decision to combine FDA and content analysis affected our sampling methodology. Using specific examples, we illustrate the contribution of the FDA to the study. Then, we indicate how subject positioning formed the link between the FDA and the content analysis. Drawing on the same examples, we demonstrate how the content analysis supplemented the FDA through tracking changes over time and providing empirical evidence of the extent to which subject positionings were deployed.
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Date Issued: 2016

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How do editors' attitudes and their perceptions of readers' interests combine with other factors to influence the publication of articles on the natural sciences in the Daily Dispatch?

- Lang, Steven

Authors: Lang, Steven
Date: 2016
Language: English
Type: Thesis , Masters , MA
Identifier: http://hdl.handle.net/10962/3893 , vital:20553
Description: This half-thesis examines how editorial values and perceptions determine the quantity and nature of science articles published in the Daily Dispatch, a newspaper distributed through large parts of the Eastern Cape in South Africa. It was predicated on the notion that South African media in general does not cover the natural sciences adequately. In order to test this assumption I decided to investigate the production and publication of science content at the Daily Dispatch as a test case. This study‘s theoretical framework draws on the normative roles of the media in a democracy developed by Christians et al. (2009) and the models of science journalism described by Secko et al. (2012) to demonstrate how two parallel conceptions of democracy set diverse journalistic objectives and engender different types of science content. Having applied an essentially political framework, this thesis uses the Hierarchy of Influences Model devised by Reese and Shoemaker‘s (2014) to explore how an array of forces acting inside and outside the news organisation can shape the publication of science articles. A quantitative content analysis is used to ascertain the number of science articles published in the first six months of 2014. It investigates which science fields received the most coverage, and how prominently the articles are positioned. As the Daily Dispatch does not have any staff dedicated to the science beat, the analysis finds out who produces the science articles that are published. The second phase of this research is a series of interviews with senior editorial staff members aimed at probing the editorial thought processes that determine when and whether specific science stories should be covered. The personal views and biases of the editorial leadership are pivotal to this research because although the newspaper commissioned surveys to determine readership preferences, there were no questions about the sciences. Senior reporters were adamant that they worked for a political newspaper and that as a significant proportion of their readership lived in socio-economically deprived circumstances, they were bound to give priority to articles aimed at improving the lot of their readers. The third phase is a qualitative content analysis of selected articles designed to reveal how science articles are constructed. The final element of this thesis, which ultimately provides an answer to the research question, draws together conclusions from the previous phases to demonstrate the linkage between editorial values and the production of science content.
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Date Issued: 2016

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How do social and personal identity, sense of place, connectedness to nature and environmental understanding influence the implementation of collective, large-scale biodiversity stewardship initiatives in South Africa?

- Potts, Tracey Ann

Authors: Potts, Tracey Ann
Date: 2016
Language: English
Type: Thesis , Masters , MSc
Identifier: http://hdl.handle.net/10962/3663 , vital:20534
Description: Biodiversity stewardship is a mechanism that is used to conserve high value biodiversity assets. Biodiversity stewardship programmes focus on areas that are under immediate threat from development or under medium to long term threat from degradation or transformation that will result in habitat loss. Biodiversity stewardship provides a solution to the resource crisis being faced by many state and provincial conservation agencies, NGO’s (Non-Governmental Organisations) and PBO’s (Public Benefit Organisations) in that it facilitates the declaration, and the subsequent improved conservation management, of private or communally owned land whilst still retaining the existing tenure. The rate of habitat loss can often be slowed, or even reversed, by proactively securing these areas and facilitating management decision-making with a focus on biodiversity outcomes without the capital investment required by the State to purchase the land. In return for conservation management actions, certain land-use restrictions and the associated opportunity costs, the State offers a suite of incentives and benefits that are, where possible, tailored to meet the needs of the landowner. Particular regions of South Africa lend themselves well to the development of biodiversity stewardship initiatives which are designed to secure ecological processes and ecosystems across a landscape or an ecological feature at scales of tens of thousands of hectares. When developing landscape level biodiversity stewardship initiatives, negotiations tend to be focussed on groups of landowners. This requires collaboration and the collective alignment of natural resource management decision-making and conservation actions amongst neighbours. Gaining a better understanding of how the social constructs of ecological understanding, place attachment, connectedness to nature, occupational identity and social and personal identity influence decision-making, behaviour and group structure is a critically important factor when developing a tool to predict the likelihood of landowners to collectively commit to long-term, legally binding biodiversity stewardship programmes. The overarching hypothesis was that the social constructs listed above influence group dynamics within the context of collective pro-conservation behaviour. Social dynamics associated with large-scale biodiversity stewardship initiatives become complex when multiple landowners are involved. Could social cohesion and group culture be influenced by aspects of identity and do these in turn develop into barriers or motivators to coordinated and sustained conservation efforts? Further influences on the successful implementation of landscape scale biodiversity stewardship initiatives could include ecological understanding, connectedness to nature and place attachment. Structured interviews were held with the landowners engaged in two separate large-scale biodiversity stewardship sites, the Compassberg Protected Environment and the Baviaanskloof Hartland, in the Eastern Cape Province of South Africa. The interviews were followed up with surveys containing psychometric scales related to the influence of ecological understanding, place attachment, connectedness to nature and aspects of identity on commitment to collective long-term, large-scale biodiversity stewardship initiatives. The results from a set of non-parametric (exact) Wilcoxon rank-sum tests showed that scores on the new ecological paradigm scale and the place attachment scale latent variables were significantly different at the two study sites, at the 10% level of significance. Demographic differences between the two study sites influenced group dynamics, collective decision-making and commitment. The relationship between the latent variables (the five psychometric scales measured) and the ancillary variables (the demographic data describing the respondents) cannot be considered conclusive; however they do provide relatively useful insights into the development of a scale or tool to measure conservation opportunity. The thesis concludes with a proposed conservation opportunity assessment tool that can be utilised alongside the existing, well refined, conservation priority assessment tools to assist in decision-making when planning large, landscape scale biodiversity stewardship initiatives in South Africa.
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Date Issued: 2016

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