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An adaptive approach for optimized opportunistic routing over Delay Tolerant Mobile Ad hoc Networks

  • Authors: Zhao, Xiaogeng
  • Date: 2008
  • Subjects: Ad hoc networks (Computer networks) Computer network architectures Computer networks Routing protocols (Computer network protocols)
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4588 , http://hdl.handle.net/10962/d1004822
  • Description: This thesis presents a framework for investigating opportunistic routing in Delay Tolerant Mobile Ad hoc Networks (DTMANETs), and introduces the concept of an Opportunistic Confidence Index (OCI). The OCI enables multiple opportunistic routing protocols to be applied as an adaptive group to improve DTMANET routing reliability, performance, and efficiency. The DTMANET is a recently acknowledged networkarchitecture, which is designed to address the challenging and marginal environments created by adaptive, mobile, and unreliable network node presence. Because of its ad hoc and autonomic nature, routing in a DTMANET is a very challenging problem. The design of routing protocols in such environments, which ensure a high percentage delivery rate (reliability), achieve a reasonable delivery time (performance), and at the same time maintain an acceptable communication overhead (efficiency), is of fundamental consequence to the usefulness of DTMANETs. In recent years, a number of investigations into DTMANET routing have been conducted, resulting in the emergence of a class of routing known as opportunistic routing protocols. Current research into opportunistic routing has exposed opportunities for positive impacts on DTMANET routing. To date, most investigations have concentrated upon one or other of the quality metrics of reliability, performance, or efficiency, while some approaches have pursued a balance of these metrics through assumptions of a high level of global knowledge and/or uniform mobile device behaviours. No prior research that we are aware of has studied the connection between multiple opportunistic elements and their influences upon one another, and none has demonstrated the possibility of modelling and using multiple different opportunistic elements as an adaptive group to aid the routing process in a DTMANET. This thesis investigates OCI opportunities and their viability through the design of an extensible simulation environment, which makes use of methods and techniques such as abstract modelling, opportunistic element simplification and isolation, random attribute generation and assignment, localized knowledge sharing, automated scenario generation, intelligent weight assignment and/or opportunistic element permutation. These methods and techniques are incorporated at both data acquisition and analysis phases. Our results show a significant improvement in all three metric categories. In one of the most applicable scenarios tested, OCI yielded a 31.05% message delivery increase (reliability improvement), 22.18% message delivery time reduction (performance improvement), and 73.64% routing depth decrement (efficiency improvement). We are able to conclude that the OCI approach is feasible across a range of scenarios, and that the use of multiple opportunistic elements to aid decision-making processes in DTMANET environments has value.
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  • Date Issued: 2008

Neuroprotective mechanisms of nevirapine and efavirenz in a model of neurodegeneration

  • Authors: Zheve, Georgina Teurai
  • Date: 2008
  • Subjects: HIV infections -- Treatment AIDS (Disease) -- Treatment AIDS dementia complex -- Treatment Nervous system -- Degeneration -- Treatment Melatonin Neurotoxic agents Quinolinic acid
  • Language: English
  • Type: Thesis , Masters , MPharm
  • Identifier: vital:3807 , http://hdl.handle.net/10962/d1003285
  • Description: AIDS Dementia Complex (ADC) is a neurodegenerative disorder implicated in HIV-1 infection that is associated with elevated levels of the neurotoxin, quinolinic acid (QA) which causes a cascade of events to occur, leading to the production of reactive oxygen species (ROS), these being ultimately responsible for oxidative neurotoxicity. In clinical studies, Non-nucleoside reverse transcriptase inhibitors (NNRTIs), efavirenz (EFV) and nevirapine (NVP) have been shown to potentially delay the progressive degeneration of neurons, thus reducing the frequency and neurological deficits associated with ADC. Despite these neuroprotective implications, there is still no biochemical data to demonstrate the mechanisms through which these agents offer neuroprotection. The present study aims to elucidate and further characterize the possible antioxidant and neuroprotective mechanisms of NVP and EFV in vitro and in vivo, using QA-induced neurotoxicity as a model. Research has demonstrated that antioxidants and metal chelators have the ability to offer neuroprotection against free radical induced injury and may be beneficial in the prevention or treatment of neurodegeneration. Hence the antioxidant and metal binding properties of these agents were investigated respectively. Inorganic studies, including the 1, 1-diphenyl-2 picrylhydrazyl (DPPH) assay, show that these agents readily scavenge free radicals in vitro, thus postulating the antioxidant property of these agents. The enhancement of superoxide radical generation and iron mediated Fenton reaction by QA is related to lipid peroxidation in biological systems, the extent of which was assayed using the nitroblue tetrazolium and thiobarbituric acid method respectively. Both agents significantly curtail QA-induced lipid peroxidation and potentially scavenge superoxide anions generated by cyanide in vitro. Furthermore, in vivo results demonstrate the ability of NVP and EFV to protect hippocampal neurons against lipid peroxidation induced by QA and superoxide radicals generated as a consequence thereof. The alleviation of QA-induced oxidative stress in vitro possibly occurs through the binding of iron (II) and / or iron (III), and this argument is further strengthened by the ability of EFV and not NVP to reduce iron (II)-induced lipid peroxidation in vitro directly. In addition the ferrozine and electrochemistry assay were used to measure the extent of iron (II) Fe[superscript 2+] and iron (III) Fe[superscript 3+] chelation activity. Both assays demonstrate that these agents bind iron (II) and iron (III), and prevent redox recycling of iron and subsequent complexation of Fe[superscript 2+] with QA which enhances neuronal damage. Both NNRTIs inhibit the endogenous biosynthesis of QA by inhibiting liver tryptophan 2, 3-dioxygenase activity in vivo and subsequently increasing hippocampal serotonin levels. Furthermore, these agents reduce the turnover of hippocampal serotonin to 5-hydroxyindole acetic acid. NVP and not EFV increase 5-hydroxyindole acetic acid and norepinephrine levels in the hippocampus. The results of the pineal indole metabolism study show that NVP increases the synthesis of melatonin, but decreases N-acetylserotonin, 5-hydroxyindole acetic acid and 5-hydroxytryptophol levels. Furthermore, it shows that EFV decreases 5-hydroxyindole acetic acid and melatonin synthesis. Behavioural studies using a Morris water maze show that the post-treatment of rats with NVP and EFV significantly improves QA-induced spatial memory deficits in the hippocampus. This study therefore provides novel information regarding the neuroprotective mechanisms of NVP and EFV. These findings strengthen the argument that these NNRTIs not only have antiviral effects but possess potential neuroprotective properties, which may contribute to the effectiveness of these drugs in the treatment of ADC.
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  • Date Issued: 2008

Geology, regional diamond exploration and diamond provenance of the proterozoic diamondiferous Umkondo conglomerates, Umkondo group, eastern Zimbabwe

  • Authors: Zhou, Takawira
  • Date: 2016
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/3598 , vital:20528
  • Description: The Umkondo Sedimentary Basin in eastern Zimbabwe has been studied by various individuals and organizations since 1901. Their interest had been in finding limestone and beryl and base metal deposits, especially copper, iron and uranium, but these occurrences had proved to be of no economic value (Watson, 1969). The recent discovery of placer diamonds within the Proterozoic basal conglomerates of the Umkondo Sedimentary Basin has now attracted worldwide interest in the basin’s diamond economic potential, in understanding of the geology, and the diamond provenance of the Umkondo conglomerates. The Umkondo Sedimentary Basin basal conglomerate placer deposit might narrowly be defined as a mega-placer because of its sheer large size and high grades, especially on the 70,000 hectare western margin diamond dispersion halo where alluvial diamonds are being mined. Bluck, et al., (2005, pp 213) defines a diamond mega-placer as: . . . a number of linked deposits that are a result of one or a continuous process of transportation and deposition and holds or have held at least >= 50 million carats at >= 95% gem quality, for example, the Orange-Vaal dispersal, off the Kaapvaal craton in South Africa. On craton placers are residual, and transient placers are eroded and deposited into the exit drainage, while terminal placers, the final depositories of diamonds with the highest chances of being mega-placers are deposited into terminal basins like oceans and foreland basins. Though data is limited at the moment, the Umkondo conglomerates caratage is likely to run into hundreds of millions of carats, with a diamond gem content of between twenty and twenty-five percent, as is indicated from recent diamond production data. The greater part of the Umkondo diamonds are likely to be lodged beneath the deep gravels of the Middle and Lower Save River basin, because small remnant tilted mountain blocks and inselbergs forming the caps of hills are what remains of the host conglomerate on the western margin of the Umkondo Basin. Areas to be examined in this document will be the geology; the mode of formation of the Umkondo basin and its sedimentary system; the regional kimberlite exploration around the basin; and diamond production in the Marange diamond field, in order to come up with indications of the provenance of the diamonds within the Umkondo conglomerates. The kimberlite clusters in and around the Umkondo sedimentary basin have all proved to be barren or only nominally diamondiferous and that the kimberlites are between 200Ma and 500Ma and thus much younger than the greater than 1.1Ga Umkondo diamondiferous conglomerates. Studies so far undertaken have not managed to point to the origin, or provenance, of the Umkondo or Marange diamonds, which were discovered on the western edge of the Umkondo Basin and in the east of the basin below the Chimanimani Mountains along the Haroni River. This paper is an attempt to clear up some of the misconceptions surrounding the Marange diamond deposit and to raise interest in the urgent rquirement to study and understand the Umkondo Basin and the origin of its diamonds. The only meaningful studies on diamond occurrence and diamond exploration of the basin were undertaken from 1996 to 2006 by Kimberlitic Searches Zimbabwe (Pvt) Ltd, the then Zimbabwe kimberlite exploration arm of De Beers, Zimbabwe, in their quest to find kimberlites, which were thought to be related to the Umkondo alluvial diamond deposit. As will be shown in the following chapters, many of the discovered kimberlites range from very low grade to non-diamondiferous, and are much younger than the Umkondo conglomerates, whose diamonds are in turn a great deal older. Thus the basic question concerning the origin or provenance of the Umkondo placer diamonds still remains unresolved. Because of the sheer size of the basin, modern, wide-area-coverage, geophysical exploration methods become appropriate to effectively generate diamond potential targets for further examination. This document will attempt to collate various data available to paint a true picture of the state of exploration within the Umkondo Basin.
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  • Date Issued: 2016

Family diversity : a South African perspective focusing on Whites in Grahamstown

  • Authors: Ziehl, Susan C
  • Date: 1998
  • Subjects: Families -- History -- Research Families -- South Africa -- Grahamstown Families Families -- Research -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:3341 , http://hdl.handle.net/10962/d1004467
  • Description: Drawing on developments in the field of family history and studies of families in contemporary settings, the study addresses the question of explaining variations in household patterns. Its empirical basis is a survey of White households in Grahamstown. The surveyed population was broken down in terms of class (occupation) and culture (language) and analyses conducted to determine if there are any statistically significant relationships between these variables and the tendency to reside in particular household structures. The question of 'family ideology' was also addressed as an attempt was made to uncover subjects' views on a variety of family-related issues. On the basis of the research results, a model of the relationship between class, culture and household structure was developed. Its application to a comparison of Black and White household structures in South Africa as well as the United States, is discussed. Finally, attempts at redefining the family are addressed and a new definition of the family proposed.
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  • Date Issued: 1998

Characterization of the distribution of platinum group elements in sulphide ores within the Merensky Reef at Modikwa and Two Rivers Platinum Mines, Eastern Bushveld Complex, South Africa

  • Authors: Zilibokwe, Nosibulelo Julie
  • Date: 2017
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/7938 , vital:21326
  • Description: The distribution of the platinum group element (PGE), in the Merensky Reef was characterized by, first determining the occurrence of the platinum group minerals (PGM), then by establishing the PGE concentration in the base metal sulphides (BMS) associated with the PGE mineralization in the Merensky Reef from selected borehole intersections, at the Two Rivers (TRP) and Modikwa Platinum Mines in the Eastern Bushveld Complex. A mineral liberation analyser (MLA) was then used to identify the PGM phases; their silicate and base metal associations; and their grain size distribution. Electron microprobe quantitative analysis and mapping were then used to determine the compositional variation of the PGM and the PGE elemental distribution in the BMS, respectively. The study showed that the BMS including pyrrhotite, pentlandite, and chalcopyrite were the principal sulphides, where pyrrhotite was most prominent with minor quantities of pyrite. Orthopyroxene, clinopyroxene and plagioclase were the most abundant primary silicate minerals identified, while secondary silicates identified included talc, serpentine and amphibole. Platinum group minerals showed three distinct groups with respect to the mineralogical association with the PGE; (i) BMS association; (ii) chromite association; and (iii) silicate association. Of the BMS, chalcopyrite showed the most dominant association with the PGMs. All samples from both mines exhibited a wide range of PGMs, including maslovite, braggite, cooperate, laurite and PGE alloys such as ferroplatinum as well as other unidentified platinum and palladium sulphides, arsenides and bismuthides, while gold was present as electrum. The PGMs ranged in size from less than a micron to about 125 microns with an average of 20 microns. The close association of PGM with BMS along the margins of sulphides indicates that the PGMs were derived from the sulphide melt. PGE distribution in the sulphides at Modikwa showed pentlandite contained the highest concentrations of palladium (up to 379 ppm) and chalcopyrite hosting the highest rhodium concentrations (up to 793 ppm). Samples from Two Rivers revealed pentlandite as the principal host to both palladium and rhodium, with concentrations reaching up to 695 and 930 ppm, respectively. Magnetite at both Modikwa and Two Rivers showed significant rhodium content, reaching up to 982 and 930 ppm, respectively. The pyrrhotite compared to other sulphides contained all the elements found in the platinum group (PPGE), namely, platinum, palladium and rhodium, with all the platinum identified found in the pyrrhotite. The concentrations for the iridium group (IPGE) namely, iridium, osmium, and ruthenium were below the detection limit. The PGE mineralization in the stratigraphy varied within each mine. The mineralization revealed top loading in the central sector (Modikwa) and bottom loading in the southern sector (Two Rivers). The sequence of the Merensky Reef at the two sectors of the Eastern Bushveld Complex showed a remarkable similarity in their mineralogy suggesting that these two sectors were formed from the same liquid or formed simultaneously within a single magma chamber; however the PGE distribution within the stratigraphy may have been controlled by the presence of cumulate sulphides.
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  • Date Issued: 2017

Using the larval parasitoid, Agathis bishopi (Nixon) (Hymenoptera: Braconidae), for early detection of false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) infested fruit

  • Authors: Zimba, Kennedy Josaya
  • Date: 2015
  • Subjects: Cryptophlebia leucotreta , Citrus -- Diseases and pests -- South Africa , Pests -- Biological control -- South Africa , Cryptophlebia leucotreta -- Detection , Parasitoids -- Hosts , Braconidae
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5919 , http://hdl.handle.net/10962/d1017186
  • Description: Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is one of the major citrus pests of economic importance for South Africa’s citrus industry. It is endemic to Africa, and therefore a phytosanitary pest with zero tolerance by most export markets. The cryptic nature of T. leucotreta makes visual inspection an inefficient method for detecting neonate larvae in fruit in the packhouse. Therefore, a more accurate method for sorting infested fruit at the packhouse, particularly for newly infested fruit could ensure market access. A recent study showed that fruit infested by T. leucotreta emit a chemical profile different from that of a healthy fruit. Several studies provide evidence that parasitoids locate their hosts feeding on fruit by exploiting the novel chemical profiles produced due to host herbivory. The aim of this study was to evaluate the potential of using the naturally occurring behaviour of a larval parasitoid Agathis bishopi (Nixon) (Hymenoptera: Braconidae) for detection of T. leucotreta infested fruit, by determining which compound in infested fruit is attractive to parasitoids. Ytube olfactometer and flight-tunnel bioassays with healthy and T. leucotreta infested fruit showed a significantly stronger response of A. bishopi female parasitoids to infested fruit. Among the volatile compounds associated with T. leucotreta infested fruit, D-limonene elicited the strongest attraction to A. bishopi female parasitoids. Attraction of mated A. bishopi female parasitoids to T. leucotreta infested fruit and D-limonene significantly increased after oviposition experience. Behavioural responses of A. bishopi female parasitoids that were associated with T. leucotreta infested fruit were investigated to determine which behaviours are distinct and interpretable. Probing and oviposition behaviours were the most noticeable and were only elicited on infested fruit when parasitoids contacted T. leucotreta frass, indicating that chemical compounds in frass are short-range cues used for final host location. Since production of D-limonene by fruit is elevated due to herbivory by different pests including mechanical injury on fruit, response of A. bishopi female parasitoids to compounds in frass offers a more specific and potentially useful mechanism for development of a detection system for T. leucotreta infested fruit. Chemical analysis of T. leucotreta frass and conditioning A. bishopi parasitoids to respond behaviourally to compounds in frass is proposed.
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  • Date Issued: 2015

Managing an inclusive school: a case study of a pilot school in Swaziland

  • Authors: Zimba, Zondani
  • Date: 2012
  • Subjects: Inclusive education -- Swaziland -- Mbabane Special education -- Swaziland -- Mbabane Learning disabled children -- Education -- Swaziland -- Mbabane Students with disabilities -- Swaziland -- Mbabane School management and organization -- Swaziland -- Mbabane
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1669 , http://hdl.handle.net/10962/d1003552
  • Description: Inclusive Education (IE) reflects the values, ethos, and culture of an education system committed to excellence by promoting education opportunities for all learners. IE is about building a more just society and ensuring the right to education for all learners regardless of their individual characteristics or difficulties (UNESCO: 2007). The kingdom of Swaziland has committed itself to high quality basic education which provides equal opportunities for all children and youth. This is evident in the Swaziland National Constitution (2006). To promote Education for All (EFA) as stated in the constitution, an IE Policy has been developed and a draft policy is in place. The programme has been operational since 2006. There are nine pilot schools and four teachers from each school who have been trained on how to handle pupils with disabilities. The programme will be rolled out to 608 primary schools by 2015. In this research, the goal was to investigate how a School Management Board responds to the challenges of managing an Inclusive School. This research is a qualitative interpretive case study based in one of the pilot schools in Mbabane in Swaziland. The study used document analysis, semi‐structured interviews and focus groups to collect data. The study revealed that the school has done much in accommodating IE as there are changes in management structures and approaches, organizational culture and operating procedures. On the other hand, there are still significant challenges such as a lack of knowledge of inclusion and negativity on the part of learners and parents. Other challenges include inadequate training for educators and lack of suitable infrastructure. The study concludes by recommending improved staff development programmes, infrastructure upgrades, acquiring appropriate teaching and learning resources and employing multidisciplinary personnel.
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  • Date Issued: 2012

Securitisation and its application to low cost housing finance in South Africa

  • Authors: Zimbwa, Allan Golden
  • Date: 2007
  • Subjects: South Africa. Constitution , Human rights -- Government policy -- South Africa , Right to housing -- South Africa , Housing -- Law and legislation -- South Africa , Housing policy -- South Africa , Low income housing -- South Africa
  • Language: English
  • Type: Thesis , Masters , MCom
  • Identifier: vital:1011 , http://hdl.handle.net/10962/d1002746 , South Africa. Constitution , Human rights -- Government policy -- South Africa , Right to housing -- South Africa , Housing -- Law and legislation -- South Africa , Housing policy -- South Africa , Low income housing -- South Africa
  • Description: Section 26 of the Constitution of South Africa Act 108 of 1996 provides that housing is a basic human right and that the government must take reasonable legislative and other measures to achieve the realisation of this right. A number of measures were taken to try to resolve this socio-economic issue. A number of housing institutions were established , various pieces of legislation were passed and housing subsidies were provided. However, housing backlogs remain a challenge. In March 1994 the housing backlog was estimated between 1,3 and 1,8 million units. When more than a million houses were provided by 2001 , the housing backlog had increased to between 2 and 3 million houses. To date subsidies in excess of R29 billion have been spent on housing provision. A study by the Department of Housing concluded that, at the current rate of increase of housing funding vis-a-vis the growing backlog and rapid urbanisation, the household backlog will not be changed in ten years' time. The United States of America (USA) had a similar low cost housing problem, but securitisation alleviated it with the participation of government agencies Fannie Mae, Ginnie Mae and Freddie Mac. In South Africa, the NHFC tried to emulate the USA model by establishing Gateway Home Loans (Pty) Limited (Gateway) in 1999. Gateway, however, was not a success. This research investigates whether securitisation can be applied in South Africa to alleviate the low cost housing issue. The study finds that there is a credit availability gap for the low income sector earning less than R8 000 per month because of the perceived risk of default and unwillingness by banks to lend to this sector. The increase in housing backlog that continues unabated, inadequate housing finance system to low income earners, the lessons learnt from the failure of Gateway, the success factors of the USA securitisation model and the sound and sophisticated South African financial system are the rationale for applying securitisation. A proposal of how to effectively apply securitisation to low cost housing in South Africa is provided with recommendations to revive the primary market.
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  • Date Issued: 2007

The ecology and control of Opuntia Aurantiaca in South Africa in relation to the cochineal insect, Dactylopius Austrinus

  • Authors: Zimmermann, Helmuth G
  • Date: 1982
  • Subjects: Cochineal insect -- South Africa Cactus -- South Africa Weeds -- Control -- South Africa Insect-plant relationships
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5612 , http://hdl.handle.net/10962/d1003061
  • Description: The cochineal insect Dactylopius austrinus De Lotto, which was released on jointed cactus, Opuntia aurantiaca Lindley, in South Africa in 1932, failed to bring the weed under an acceptable level of control in spite of the encouraging results during the first few years after release. The reasons for this apparent failure were never clearly understood. In 1957 the State embarked on an intensive herbicidal control programme which is still in force today. This sustained and expensive programme has undoubtedly reduced the density of the weed in most areas but has failed to solve the problem and the plant continues to expand its range. The biological control of o. aurantiaca in South Africa has been fundamentally influenced by this chemical control campaign. The relationship between chemical and biological control methods is reported in this study.
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  • Date Issued: 1982

The physical activity status and the impact of lifestyle behaviours on workplace productivity and absenteeism of Transnet employees

  • Authors: Zimmermann, Sharnae Vanessa
  • Date: 2021-10
  • Subjects: Transnet (Firm : South Africa) Employees , Absenteeism (Labor) South Africa Durban , Labor productivity South Africa Durban , Exercise , Sedentary behavior , Lifestyles
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10962/190077 , vital:44961
  • Description: Increased sitting time, insufficient physical activity and sub-optimal body composition are all contributing to the global disease burden. This is made evident by increases in obesity, type II diabetes, cardiovascular diseases (i.e. hypertension and strokes), cancer and other non-communicable diseases resulting in absenteeism and reduced productivity in the workplace. The global rise in sitting time and physical inactivity is caused, in part, by changes in transport convenience, work roles and technological advancements. Employees working in office environments or driving trains sit for prolonged periods; something which is evident in the industry that Transnet operates in. Sitting time and physical inactivity are independent risk factors for non-communicable diseases with poor nutrition, smoking, alcohol consumption and psychological wellbeing, being separate constructs. The purpose of the study is to determine the levels of sedentary behaviour, physical inactivity, obesity, nutrition, alcohol consumption, smoking, non-communicable disease risk, mental wellbeing and their association with productivity and absenteeism in office workers and train drivers at Transnet Freight Rail, Durban. A cross-sectional study was done with 40 participants, 20 office workers and 20 train drivers. Stature (175.80 ± 9.43 ±cm) and body mass (83.85 ± 20.31 kg) were measured; and body mass index calculated (26.98 ± 5.37 kg.m2). Physical activity levels, sedentary behaviour, body mass index and other lifestyle factors were explored using an amended version of The Health and Wellbeing survey, a self-report measure. The results revealed that there was a high prevalence of sedentary behaviour (train drivers = 7.85 ± 2.21 and office workers = 8.3 ± 1.03), particularly among office workers. Most of the participants had a relatively high body mass index, placing in the overweight and obese category, particularly among train drivers. The prevalence of physical inactivity was marginally higher for office workers compared to train drivers. There were significantly (p<0.05) higher levels of physical activity within train drivers with a moderate effect size. There were limited associations found between lifestyle factors and sickness absenteeism and worker productivity. Obesity had the most prominent relationship with noncommunicable diseases, followed by high levels of sedentary behaviour, not meeting physical activity guidelines, obesity, overweight, and prolonged sitting time at work. A significant and moderate correlation was found between obesity and absenteeism (train drivers: r = 0.32 and office workers: r= 0.46), however, no associations were found between sedentary behaviour, physical activity and fruit and vegetable intake and absenteeism. Lastly, the association between physical activity and productivity among the train drivers was low negative (r=-0.15) which was not significant (p>0.05). The associations between physical activity and productivity among office workers, however, was both significant (p<0.05) and moderate positive (r=0.39). The vegetable intake among the office workers showed a significant (p<0.05) moderate positive association with productivity (r=0.49). The association between vegetable intake and productivity among the train drivers was not significant (p>0.05) and low positive (r=0.16). There was a significant (p<0.05) and moderate positive association between fruit intake and productivity among both train drivers (r=0.43) and office workers (r=0.47). No significant associations between sedentary behaviour and obesity and productivity were found. The current study provided new insight into the risks associated with lifestyle factors of office workers and train drivers in the transportation sector. The poor lifestyle factors, together with the high prevalence of sedentary behaviour and physical inactivity, provide ideal opportunities for future interventions to focus on workers productivity and overall wellbeing. The job design of train drivers and office workers does not place significant importance on employee health and wellness. Essentially they are not “healthy” but they work productively, giving reason as to why employee wellness is not a priority for employers. The current findings of the study suggest that adopting regular physical activity, healthy dietary patterns and reduced sitting time should be promoted as key components of lifestyle interventions for the prevention of non-communicable diseases in office workers and train drivers. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2021
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  • Date Issued: 2021-10

Information and propaganda in the federation of Rhodesia and Nyasaland with special reference to print and radio propaganda for Africans, 1953-1963

  • Authors: Zimudzi, Tapiwa Brown
  • Date: 2017
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/6957 , vital:21204
  • Description: This thesis contributes to the history of the information and propaganda policy and practice of the government of the Federation of Rhodesia and Nyasaland by examining this government's pro-Federation print and radio propaganda for Africans in the Federation. Using a multi-theoretical approach, it analyses the character of this propaganda, highlighting its main methods and themes as well as the policy considerations, plus political and economic circumstances that gave rise to it. It also discusses how Africans in the Federation reacted to this propaganda and assesses its effectiveness in gaining the support of these Africans for Federation and the policies of the Federal government. The thesis argues that Federal government propaganda aimed at gaining the support of Africans for Federation was predominantly panic-driven propaganda and was the product of an information panic that lay at the heart of the very idea of Federation itself. This information panic arose out of the Federal government's belated recognition of the strength of African opposition to Federation and of how this opposition seriously threatened the continued survival of the Federation. It is also argued that this panic-driven pro-Federation propaganda elicited largely hostile reactions from the majority of Africans in the Federation and failed to persuade them to support Federation.
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  • Date Issued: 2017

Development and assessment of sustained release stavudine loaded microparticles

  • Authors: Zindove, Chiedza Cathrine
  • Date: 2014
  • Language: English
  • Type: text , Thesis , Masters , MPharm
  • Identifier: http://hdl.handle.net/10962/54722 , vital:26603
  • Description: Stavudine (D4T) has been used as first line treatment for HIV/AIDS and is part of highly active anti retroviral treatment (HAART). It is an affordable medicine and its use is beneficial in resource limited settings. However D4T exhibits dose dependent side effects that may lead to non-adherence in patients. This study was undertaken to formulate, develop and manufacture a dosage form that could reduce dose dependent side effects by decreasing the dose of D4T but still exhibit antiretroviral (ARV) activity. The use of sustained release (SR) formulations of D4T that ensure constant levels of the D4T in the body would not only optimize therapy but also reduce the incidence of side effects thereby increasing patient adherence. SR microparticles containing 30mg D4T were manufactured and loaded into size 3 hard gelatine capsules prior to analysis. The D4T microparticles were manufactured by microencapsulation using non-aqueous oil-in-oil solvent evaporation approach. D4T-excipient, excipient-excipient interactions and D4T purity were assessed using Infrared Spectroscopy (IR), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Copolymers synthesized from acrylic and methacrylic acid esters viz., Eudragit® RSPO and S100 were used as rate retardant materials and the effect of microcrystalline cellulose (Avicel® PH102) on the microparticles was also investigated. Magnesium stearate was used as a droplet stabilizer and n-hexane was added to harden the microspheres formed in a liquid paraffin continuous phase. The microparticles were optimized using a Box Behnken design and Response Surface Methodology (RSM). The microparticles were characterized in terms of their flow properties and encapsulation efficiency (% EE), in addition to visualization of the surface morphology with Scanning Electron Microscopy. In vitro D4T release studies were performed using USP Apparatus III in media of different pH and the samples were analysed using a validated High Performance Liquid Chromatographic (HPLC) method with ultraviolet (UV) detection that had been developed and optimized using a Central Composite Design (CCD). The method was validated according to ICH guidelines. The IR spectra and DSC thermographs revealed that D4T exhibited thermal stability and there was no evidence of D4T-excipient and excipient-excipient interactions. The microparticles that were produced were white, free flowing and were obtained in a high yield with high encapsulation efficiency. Scanning Electron Microscopy studies revealed that the microparticles were spherical and porous in nature. In vitro D4T release extended to 12 hours and the mechanism of release was established using model dependent methods by fitting the data to a Zero order, First order, Higuchi and Hixson Crowell model. It was observed that the mechanism of D4T release was diffusion-controlled and that the data was best fitted to the Higuchi model with correlation coefficients > 0.9. The release mechanism was confirmed using the Korsmeyer-Peppas model that revealed that most of the formulations exhibited anomalous transport kinetics with the release exponent, n, ranging from 0.5
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  • Date Issued: 2014

An interpretive analysis of the experiences of adults working as university support staff

  • Authors: Zini, Thembela Nomonde
  • Date: 2021-10-29
  • Subjects: Universities and colleges South Africa , Universities and colleges Employees , Universities and colleges Sociological aspects , Identity (Psychology) , Identity (Psychology) Social aspects , Work Psychological aspects , Work Social aspects , Interpretive Phenomenological Analysis (IPA)
  • Language: English
  • Type: Masters theses , text
  • Identifier: http://hdl.handle.net/10962/188888 , vital:44795
  • Description: Work means different things to different people and the different meanings they make of their work has the unique ability of contributing to a sense of identity. Support staff have to negotiate their personal identities and social identities to develop a work identity in the complex South African context that has its unique challenges. Exploring how support staff make sense of their experiences, when it comes to their identities, reveals what identity work strategies they use. An interpretative phenomenological method of inquiry was employed as an initial research method to explore the aspects that impact on the identity formation of support staff at Rhodes University. The study aims to investigate how support staff have constructed a work identity through their constructions of their experiences. Six participants were recruited through a purposive sampling method and data were collected using semi-structured interviews. The study revealed that support staff use the following identity work strategies to negotiate their identities: Financial, Personality, Career mobility, Roles, Status and Esteem, Subjective wellbeing. These themes were derived from the narratives of the participants, using the emphases in the data and suggest that support staff use identity work strategies both outside and within the workplace, when constructing their work identities. The study illustrates that as people ascribe different meanings to work, they will define and negotiate their identities in the workplace based upon those meanings. Identity work is indeed challenging for support staff because they need to use identity strategies that are enhancing to their self-esteem. Identity work is a challenging task because of the many tensions and demands of modern society, as adults negotiate their needs to provide for families and to find ways to construct their job status in positive ways. , Thesis (MA) -- Faculty of Humanities, Psychology, 2021
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  • Date Issued: 2021-10-29

Racism against Black soccer players in the English Premier League

  • Authors: Zinyemba, Douglas Takudzwa
  • Date: 2023-10-13
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/425300 , vital:72227
  • Description: This study analyses racism against black players in the English Premier League. To that end, this thesis studies online articles published between 2018 and 2021 by two British tabloids, namely, The Daily Mail and The Sun, to make sense of the various ways in which black soccer players experience racism. This thesis uses the theoretical concept of “racial xenophobia” to analyse and understand expressions of antipathy towards black players playing in the Premier League. A key finding in the thesis suggests that fans and players racially abuse black players in the stadiums by liking them to animals and treating them as sub-human. Another finding in the study is that fans use the bad performances of black players as an excuse to racially abuse them via social media platforms. Social media in the 21st century has now accelerated the rate at which racism is perpetrated as fans now have more access to players through their accounts. The study also found that tabloids do not only report about racist abuse but are also guilty of portraying black players in racially stereotypical ways. This research concludes that racism against black players remains a constant feature of football in the English Premier League from the time black players started to feature in the sport in the 1970s. , Thesis (MA) -- Faculty of Humanities, Political and International Studies, 2023
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  • Date Issued: 2023-10-13

A history of the German settlers in the Eastern Cape, 1857-1919

  • Authors: Zipp, Gisela Lesley
  • Date: 2013
  • Subjects: Colonists -- Eastern Cape -- 19th Century Immigrants -- Germany -- History Immigrants -- Germany -- Social life and customs
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:3609 , http://hdl.handle.net/10962/d1004215
  • Description: This thesis came into being as the result of a question innocently posed to me three years ago: Why do some towns in the Eastern Cape have German names? This thesis is not so much an answer to that question (which is answered in the following paragraphs) as an attempt to answer the questions that followed: Were the Germans really as benevolent and hard-working as much of the most readily available literature implies? Why did the military settlers leave and the peasant farmer settlers remain? What was the nature of relationships between the German settlers and other groups in the area? How did the German settlers see themselves? The existing literature provides the historic details, more or less, but not the context and explanations I sought. As such, I set out to find them and document them myself, addressing three main questions: 1. What was the (changing) nature of the German settlers' day-to-day lives between 1857 and 1919? 2. How was a German identity maintained/constructed within the German communities of the Eastern Cape between 1857 and 1919? 3. How did the Germans interact with other groups in the area? In answering these questions, I have also provided the necessary background as to why these settlers chose to come to South Africa, and why some of them left. I have limited this study to the period between 1857 and 1919 so as to include the First World War and its immediate aftermath, a time when enmity between Great Britain and Germany would have made life difficult for German descendants in the Union of South Africa. Introduction, p. 7.
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  • Date Issued: 2013

Land reform and rural livelihoods of evicted farm workers: a case study of Radway Green Farm Project

  • Authors: Zishiri, Kudzanai
  • Date: 2017
  • Language: English
  • Type: Thesis , Masters , MSocSc
  • Identifier: http://hdl.handle.net/10962/44377 , vital:25402
  • Description: The land issue has remained a contentious one more than two decades into a democratic South Africa. With the dispossession of the indigenous people from their land stretching back as far as 1913, eviction of farm workers and farm dwellers has increased tremendously even in the post-Apartheid era. Thus, the main goal of this study is to analyse the impact of the eviction on the Radway Green farm workers’ community and to examine the factors affecting the generation of livelihood activities in their new settlement. In doing so, I used the Sustainable Rural Livelihoods Approach (SRLA) as my theoretical framework as it conceptually grounds my area of study. It was employed to analyse data gathered from the field through in-depth interviews, focus groups, key informant interviews and descriptive observation of the case study. The centrality of the SRLA concept is on rural development, poverty eradication and the ability or sustainability of the vulnerable and poor to cope with stresses and shocks as they make a living (Scoones, 1998: 5). In that regard, the theoretical framework became an important cornerstone in analysing the impact of eviction of the Radway Green farm workers’ community and examining the factors affecting the generation of livelihoods activities in their new settlement. To analyse the research findings, various themes were utilised Forced Evictions and Resettlement; Eviction or Displacement; The Struggles of Recreating Livelihoods; The Need for Security of Land Tenure and Access to Infrastructure. Under these themes, the study revealed how the eviction was detrimental to the livelihoods of the farm workers and farm dwellers as they lost the land that was a primary source for the construction of their livelihoods. They lost employment, homes, agricultural land for food security and natural resources, social and family structures and most importantly cultural disruption. It is well documented that the rural poor who constitute the farm workers and the farm dwellers are some of the vulnerable people who need constant governmental support through the promulgation of laws that protect them and assist in livelihood construction. Thus, this study also served to examine how the evicted workers and their families have settled into their new homes and how they, in conjunction with the Department of Rural Development and Land Reform and any other government agencies are faring in terms of the establishment of income generating projects for their livelihoods at the new settlement.
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  • Date Issued: 2017

Attempts to improve the teaching of English by Black teachers in selected areas of the Eastern Cape and the Transkei, through educational workshops and resource materials

  • Authors: Ziskovsky, Lorraine
  • Date: 1986
  • Subjects: English language -- Study and teaching -- South Africa -- Foreign speakers Education -- South Africa Teaching -- Aids and devices
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1410 , http://hdl.handle.net/10962/d1003060
  • Description: This action research study covers the period November 1983 to August 1985, and is an ethnographic account of what started as a small-scale attempt to assist black teachers of English at the Standard 6, 7 and 8 level, in Grahamstown. During this period, the writer was employed by the South African Council for Higher Education's Grahamstown branch as a part- time English tutor of black and coloured teachers engaged in private study for the Joint Matriculation Board and UNISA. It was under Sached's aegis that the project started, with the writer holding the belief that poor matriculation examination results obtained by blacks were at least partially caused by poor English language communication skills. It was hoped that assistance to black teachers of English as a second language (ESL) at the chosen level (Standards 6, 7 and 8) would be of some help in freeing black students from the necessity of having to achieve academically and linguistically at the same time, in Standards 9 and 10.
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  • Date Issued: 1986

Machine learning methods for calibrating radio interferometric data

  • Authors: Zitha, Simphiwe Nhlanhla
  • Date: 2019
  • Subjects: Calibration , Radio astronomy -- Data processing , Radio astronomy -- South Africa , Karoo Array Telescope (South Africa) , Radio telescopes -- South Africa , Common Astronomy Software Application (Computer software)
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/97096 , vital:31398
  • Description: The applications of machine learning have created an opportunity to deal with complex problems currently encountered in radio astronomy data processing. Calibration is one of the most important data processing steps required to produce high dynamic range images. This process involves the determination of calibration parameters, both instrumental and astronomical, to correct the collected data. Typically, astronomers use a package such as Common Astronomy Software Applications (CASA) to compute the gain solutions based on regular observations of a known calibrator source. In this work we present applications of machine learning to first generation calibration (1GC), using the KAT-7 telescope environmental and pointing sensor data recorded during observations. Applying machine learning to 1GC, as opposed to calculating the gain solutions in CASA, has shown evidence of reducing computation, as well as accurately predict the 1GC gain solutions representing the behaviour of the antenna during an observation. These methods are computationally less expensive, however they have not fully learned to generalise in predicting accurate 1GC solutions by looking at environmental and pointing sensors. We call this multi-output regression model ZCal, which is based on random forest, decision trees, extremely randomized trees and K-nearest neighbor algorithms. The prediction error obtained during the testing of our model on testing data is ≈ 0.01 < rmse < 0.09 for gain amplitude per antenna, and 0.2 rad < rmse <0.5 rad for gain phase. This shows that the instrumental parameters used to train our model more strongly correlate with gain amplitude effects than phase.
  • Full Text:
  • Date Issued: 2019

An exploration of health professional's perceptions of the role of clinical psychologists

  • Authors: Zitianellis, Marina Sophia
  • Date: 2005
  • Subjects: Community health services -- South Africa , Community mental health services -- South Africa , Medical personnel -- South Africa -- Attitudes , Primary health care -- South Africa , Clinical psychologists
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:3091 , http://hdl.handle.net/10962/d1002601 , Community health services -- South Africa , Community mental health services -- South Africa , Medical personnel -- South Africa -- Attitudes , Primary health care -- South Africa , Clinical psychologists
  • Description: The South African government has initiated the transformation of health services in the country towards primary health care (PHC) in order to provide comprehensive care to individuals and families. The move to PHC involves an increased need for collaboration between health professionals. It is proposed that for effective team-work to take place, an understanding of the roles and functions of team members is imperative in providing quality mental health care. This study explored health professionals’ perceptions of the role and function of clinical psychologists working as part of a health care team in a community context. Three focus groups and three individual interviews were conducted with social workers, nurses and doctors. The data was then processed and analysed using a grounded theory method. The research highlighted the importance of knowledge, and how this affects referrals, perceptions, inter-professional relations and the perceived usefulness of clinical psychology and clinical psychologists. What is of significance is the potential power that the health professionals have as gatekeepers between the general public and clinical psychologists.
  • Full Text:
  • Date Issued: 2005

The spatial planning of racial residential segregation in King William's Town : 1826-1991

  • Authors: Zituta, Heyman Mandlakayise
  • Date: 1997
  • Subjects: Apartheid -- South Africa -- King William's Town , City planning -- South Africa -- King William's Town , King William's Town (South Africa) -- History
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:4855 , http://hdl.handle.net/10962/d1005531 , Apartheid -- South Africa -- King William's Town , City planning -- South Africa -- King William's Town , King William's Town (South Africa) -- History
  • Description: This study investigates the spatial planning of racial residential segregation in King William's Town, induding its former homeland township of Zwelitsha, from 1826 to 1991. The first settlement in the 'white' King William's Town, Brownlee Mission Station, was established in 1826.The town of King William's Town was developed from this settlement. The racial laws which were applied to segregate blacks nationally and locally came to an end in 1991. Primary sources of information were used to determine whether King William's Town was planned along racial lines and to determine the major role players who formulated and implemented the policy. Key sources were archival material, newspapers, maps, interviews, Deeds Office files and the work of other scholars. The establishment of the towm from its genesis as a mission station and a military base is traced and the effects of this legacy on racial separation is detailed. It was found that racial planning of residential areas in King William's Town had been practised in this small town for a long time (prior to the Group Areas Act). The implementation of this policy was marked by forced removal of blacks from areas which were regarded as being for whites. These predominently African concentrations on the east bank of the Buffalo River were relocated to the west bank which was regarded as a black area.An anomalous incident was discovered in this study namely that these racial removals took place before the central state introduced national policy which compelled all local states to plan their residential areas along ethnic considerations. In parallel with the practice of segregation in King William's Town, the township of Zwelitsha was developed adjacent to the town by the government. As this thesis reveals, the development of Zwelitsha was intimately related to that of King William's Town. The major role players in planning residential areas on racial basis were identified as the municipal Council of King William's Town. They were involved in planning racially segregated areas before and after the Group Areas Act. They (the Council) succeeded in closing all freehold locations in the town (1940) and forced the residents to become their tenants who rented dwellings in the west bank municipal location. There were attempts to incorporate this municipal location into the neighbouring homeland township of Zwelitsha. This move was eventually accomplished when all townships in the vicinity of King William's Town were amalgamated to form King William's Town Transitional Local Council in terms of the Local Government Transition Act of 1994 (Government Gazette No. 15468 of 2nd February 1994).
  • Full Text:
  • Date Issued: 1997
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