The predictors of student performance in a blended learning environment at Higher Education Institutions (HEIs) in Tanzania: a case study conducted at the University of Dar-es-Salaam
- Authors: Kabudi, Tumaini John
- Date: 2019
- Subjects: Prediction of scholastic success -- Tanzania -- Case studies , Motivation in education -- Tanzania -- Case studies , Academic achievement -- Tanzania -- Case studies , Blended learning -- Tanzania -- Case studies , Chuo Kikuu cha Dar es Salaam -- Students
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/68358 , vital:29242
- Description: Blended Learning is an important technological platform which has the potential to enhance the efficiency and efficacy of educational provision, especially in Tanzania universities. Despite a high level of investment into Blended learning, students face various challenges that have impeded them performing well in Blended learning courses. The purpose of this research is to examine and explore how student’s performance in a Blended learning environment is influenced by motivation and learning strategies; using the University of Dar es Salaam as a case study. This is a pragmatic research that utilises a mixed research design. The research design includes both qualitative design (in-depth single case study) and quantitative design (survey). The target population for this study is students participating in Blended learning modules. Primary data will be collected by means of Motivational Strategies for Learning Questionnaire and observation. It was found that motivation and learning strategies are significant predictors of student performance in a Blended learning environment. In terms of the motivation categories, Intrinsic Goal Orientation and Self-efficacy have statistically significant effect on student performance. With learning strategies sub factors, it was found out that Rehearsal, Effort Regulation and Peer Learning have significance effect on student performance. Moreover, age and gender significantly influence performance. The findings obtained are significant in building a better understanding of the influence that the mentioned predictors have on predicting the performance of students in Blended learning courses in Tanzania.
- Full Text:
- Date Issued: 2019
The preparation of BODIPY and porphyrin dyes and their cyclodextrin inclusion complexes and Pluronic® F-127 encapsulation micelles for use in PDT and PACT
- Authors: Molupe, Nthabeleng
- Date: 2019
- Subjects: Dyes and dyeing -- Chemistry , Drug delivery systems , Fluorescence spectroscopy , Cancer -- Photochemotherapy , Photosensitizing compounds -- Therapeutic use , Cyclodextrins -- Biotechnology , Nanoparticles
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/117574 , vital:34528
- Description: Several novel BODIPY dyes ((4,4′-difluoro-1,7-tetramethyl-3,5-(3-dithiophene)-2,6-diiodo-8-(4-dimethylamino)-4-bora-3a,4a-diaza-s-indacene (1c), 4,4′-difluoro-1,7-tetramethyl-3,5-(3 dithiophene)-2,6-diiodo-8-(4-methylthio)-4-bora-3a,4a-diaza-s-indacene (3c) and 4,4′-difluoro-1,7-tetramethyl-3,5-(4-dibenzyloxybenzene)-2,6-diiodo-8-(4-methylbenzoate)-4 bora-3a,4a-diaza-s-indacene (4c)) and porphyrins (tetraacenaphthylporphyrin (7a) and Sn(IV) tetraacenaphthylporphyrin (7b)) were synthesized and characterized. Previously reported BODIPY dyes (4,4′-difluoro-1,7-tetramethyl-3,5-(2-dihydroxy)-2,6-diiodo-8-(4-bromo)-4-bora-3a,4a-diaza-s-indacene (5) and 4,4′-difluoro-1,7-tetramethyl-3,5-(2-dithiophene)-2,6-diiodo-8-(phenyl)-4-bora-3a,4a-diaza-s-indacene (6)) were also used. Pluronic® F-127 and cyclodextrins were used as solubilizing drug delivery agents for the synthesized BODIPY dyes. The encapsulation of BODIPY dyes with Pluronic® F-127 micelles improved the water solubility of the BODIPY 5. Further modification of Pluronic® F-127 by coating with folate-functionalized chitosan for targeted delivery of BODIPY 1c and 6 was explored. The BODIPY dyes and their encapsulation complexes exhibited significant inhibition of human MCF-7 breast cancer cell growth. When cyclodextrins were used as nanocarriers, the inclusion complexes of BODIPY 4c with mβCD were found to enhance the water-solubility of the dye. Greater photoinactivation of Staphylococcus aureus was observed for the inclusion complexes when compared to the effect of solutions of non-complexed BODIPY 4c. The cyclodextrin inclusion complexes of porphyrin 7b with mβCD were also found to enhance the water-solubility of 7b. When the photodynamic effect was evaluated, solutions of the porphyrin alone and their inclusion complexes were found to have significant photodynamic effects against human MCF-7 breast cancer cells.
- Full Text:
- Date Issued: 2019
The relative roles of ecosystem services and disservices in rural livelihoods in the Eastern Cape, South Africa
- Authors: Herd-Hoare, Shannon
- Date: 2019
- Subjects: Ecosystem services -- Health aspects -- South Africa , South Africa -- Rural conditions , Biodiversity -- South Africa -- Health aspects , Rural development -- South Africa -- Health aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/94080 , vital:30998
- Description: Since the publication of the Millennium Ecosystem Assessment report there has been a marked increase in research into various aspects of ecosystem services (ES). While ES are essential to human wellbeing, the literature has overlooked that some ecosystem goods and services also undermine human wellbeing. These are known as Ecosystem Disservices (EDS). This study aims to counter this imbalance in research, specifically in the context of rural livelihoods which are frequently dependent on local ES but often ill-equipped to manage EDS. The objectives of this study, conducted in three rural villages along a gradient of habitat diversity, were to identify a range of ES and EDS, determine their perceived contributions to or effects on the wellbeing of respondents, and identify modifications in livelihood strategies in response to EDS. The research made use of household surveys in conjunction with participatory learning and action techniques, such as focus group discussions in which ranking and trendline exercises, timelines, and participatory mapping were conducted. Findings indicated that although numerous participants were involved in the harvest of multiple ES, such as Non-Timber Forest Products (NTFPs), livestock outputs, crops and marine wildlife, they simultaneously experienced losses from EDS, such as ticks, unpalatable grass species, monkeys, and Lantana camara invasion which undermined livelihoods to varying degrees. The role of ES and EDS in livelihoods was expressed in economic terms, representing a common framework with which to illustrate the magnitude of their contribution or loss. For example, the average value of livestock goods and services, amongst those who owned and used outputs, was highest in the least biodiverse village at R9 753 per annum, while the corresponding value of potential livestock goods and services lost due to EDS, despite active implementation of prevention measures, totalled R22 426. Further, the average value of cultivated plots in the most biodiverse village could have totalled approximately R20 958, but because of EDS, represented less than 20% of this value. Further, the findings highlighted that the most biodiverse village also had the highest number of EDS, supporting Dunn (2010) who hypothesised that the number of EDS increases with the number of ES. Based on these findings, I propose that a comprehensive framework which systematically contextualises both the positive and negative contributions of ES is needed to grasp the full picture of how local people conceive and engage with nature to facilitate an understanding of the resulting practices and processes.
- Full Text:
- Date Issued: 2019
The remote sensing of fires and their effects on soil properties in the uKhahlamba Drakensberg Park
- Authors: Moore, Natasha Jade
- Date: 2019
- Subjects: Remote sensing -- South Africa -- KwaZulu-Natal , Soil ecology -- South Africa -- KwaZulu-Natal , Grassland fires -- South Africa -- KwaZulu-Natal , Grassland fires -- Remote sensing -- South Africa -- KwaZulu-Natal , Soils -- Effect of fires on -- South Africa -- KwaZulu-Natal , uKhalamba Drakensberg Park (South Africa)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/94400 , vital:31042
- Description: Fires are a common and natural occurrence globally and specifically on the African continent. The Drakensberg Mountains are home to southern Africa’s high-altitude fire-climax grasslands, where fire is the dominant management tool. Fire is used to maintain the grasslands in the uKhahlamba Drakensberg Park (UDP) World Heritage Site, located on the eastern escarpment of the KwaZulu-Natal Drakensberg. This study aimed to investigate the spatial and temporal frequency of fires using remote sensing, and to investigate the effect of fire frequency on soil properties in the UDP. Remote sensing offers a set of supportive tools for the management of this sensitive vegetation and specifically to assess the frequency and spatial extent of fires. Field assessments can then be used to assess the impact of fires. Remotely sensed data were used to determine fire frequency and the spatial extent of fires in the UDP. The Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) active fire detection point data were processed to investigate the temporal resolution of fires. Landsat 5 and 8 imagery were utilised for conducting Normalised Burn Ratios (NBR) to determine the spatial extent of the burn scars of fires. The results from the remotely sensed data were used to select study sites for accessing the effects of fire frequency on soil properties. The remote sensing results showed the main fire season in the UDP was from May to October, and annual burn scars from the available Landsat data for 1998 to 2017 ranged from 22.5% to 57.67% of the UDP. Remote sensing was shown to be an effective tool for monitoring fires in the UDP, with a combination of satellite data producing the best results. Soil properties were highly varied across the UDP. Environmental factors were shown to have a more significant influence on soil properties than fire frequency. This study highlighted the complex nature and diversity of fires and soils across the UDP.
- Full Text:
- Date Issued: 2019
The role of gardening in improving community resilience in rural areas: a case study of Raymond Mhlaba, Port St Johns and Ingquza Hill Local Municipalities, Eastern Cape Province, South Africa
- Authors: Hendrick, Namhla Andiphile
- Date: 2019
- Subjects: Community gardens
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/17224 , vital:40867
- Description: The increase of challenges in rural areas especially in developing countries has widened the vulnerability of rural people in the rural communities. This study has found that gardening has become the weapon to defend rural people and communities in developing countries against poverty and other hardships, since gardening in rural communities has the possibility to act as sustainable livelihood strategy. Semi structured questionnaire was used to collect primary data from smallholder farmers in the three local municipalities (Raymond Mhlaba, Port St Johns and Ingquza Hill local municipalities). The research investigated both home and community gardening. Multistage sampling was employed to select the sample. In stage one, the three Local Municipalities (LM’s) were purposively selected. In stage two, farmers were grouped into wards and communities and samples drawn in such a way that each group was well represented. This was followed by using quota sampling through the census statistics to determine farmers who are practising gardening whether it is community gardening or household gardening in these three local municipalities. Finally, random sampling was used to select a sample of 203 households that are undertaking some form of gardening (home or community) and are willingness to participate in the study. The Statistical Package for Social Sciences (SPSS version 24) was used to analyse the data by means of descriptive statistics and logistic regression model. The results confirm the strong links between home or community gardening and community resilience and that the influence is conditioned by a range of socioeconomic and demographic characteristics, including, age, occupation, access to extension officer and farming experience. In the light of the foregoing, it is recommended that households and communities be encouraged establish and operate home and/or community gardens as a strategy for coping with adversities that rural areas confront from time to time. In line with that, social interactions must be encouraged in communities because such interactions increase resilience in the sense that they build confidence in community members and a strong sense of belonging and trust. The role of education in enhancing access to information and knowledge that promote community resilience to disasters and shocks needs to be recognized and incorporated in community planning
- Full Text:
- Date Issued: 2019
The role of non-timber forest products (NTFPs) in the livelihoods of communities in Alfred Nzo District Municipality, Eastern Cape Province
- Authors: Thinyane, Zingisa
- Date: 2019
- Subjects: Non-timber forest products
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14737 , vital:40077
- Description: Non-timber forest products (NTFPs) are renewable natural resources which are harvested by local communities from the surrounding homesteads, fields, grazing lands, woodlands, grasslands and natural habitats. The term NTFP may be used in reference to biological products collected from the domesticated land, semidomesticated land or from the wild. This study examined the use of NTFPs in Alfred Nzo District Municipality, Eastern Cape Province, South Africa, assessing their consumption patterns and contribution to the household well-being. Data on NTFP identity and utilization in the study area were gathered through community focus group discussions and household surveys using semi-structured questionnaires between April 2017 and May 2018. A sample of 124 participants selected via snowball-sampling technique provided detailed accounts on diversity and utilization of NTFPs in the study area. A total of 59 species and eight extractable NTFPs were utilized by the communities in Alfred Nzo District Municipality. The identified eight use categories were herbal medicine (39.0%), edible plants and mushroom (18.0%), firewood (11%), bushmeat (10.0%), forage (9.0%), construction material (6.0%), ceremonial uses (2.0%) and others with miscellaneous uses (5.0%). Popular NTFPs with use values exceeding 0.50 include Agapanthus africanus (L.) Hoffmanns, Bulbine latifolia (L.f.) Spreng., Centella asiatica (L.) Urb, Elephantorrhiza elephantina (Burch.) Skeels, Hypoxis hemerocallidea Fisch., C.A. Mey & Avé-Lall and Leonotis leonurus (L.) R. Br., all used as herbal medicines, Agapanthus africanus (L.) (herbal medicine and ornamental), Datura stromonium L. (herbal medicine, forage and firewood), Dicerothamnus rhinocerotis (L.f) Koekemoer (herbal medicine and fumigant), Aepyceros melampus Lichtenstein, Pavo cristatus L., Struthio camelus L. and Xerus inauris Hemprich & Ehnrenberg as bushmeat. Information on diversity, consumption ii patterns and contribution of NTFPs to livelihood needs of households may enable policy makers and government officers to draft policies required for sustainable management of NTFPs.
- Full Text:
- Date Issued: 2019
The socio-economic importance of indigenous vegetables to the Ntuze smallholder farming community in KwaZulu-Natal, South Africa
- Authors: Qwabe, Qinisani Nhlakanipho
- Date: 2019
- Subjects: Indigenous crops -- Economic aspects -- South Africa -- KwaZulu Natal , Vegetables -- South Africa -- KwaZulu Natal Farmers -- Economic aspects -- South Africa -- KwaZulu Natal , Farms, Small -- South Africa -- KwaZulu Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30287 , vital:30927
- Description: South Africa continues to face multiple socio-economic challenges – one of the direst being food insecurity, especially in rural areas. Compounding the challenges is the impact of changing weather patterns on agriculture. The current study presents evidence indicating that indigenous vegetables provide a sustainable yet inexpensive answer to several of these challenges. The research was aimed at determining the socio-economic impact of indigenous vegetables in the Ntuze community of northern KwaZulu-Natal. A mixed-methods methodology was employed to achieve a holistic understanding of the relationship between the use of indigenous vegetables and socio-economic influences. The study discovered that indigenous vegetables play an important role in the livelihood strategy of this rural farming community. Findings revealed that the utilisation of indigenous vegetables makes an essential contribution to the livelihoods and well-being of the Ntuze people, especially in terms of curbing food poverty, income generation and medicinal benefits. However, the value of these vegetables was found to be appreciated mostly by the elderly. Conclusions therefore indicate a possible decline in future production and use of indigenous vegetables if indigenous knowledge is not passed on to the next generation. Integration of indigenous knowledge in agricultural technology transfer programmes is therefore vital to promote production of indigenous vegetables as a sustainable food resource. Actively addressing the stigma attached to indigenous vegetables as being “low-status food” is also crucial to enhance perception and understanding of the value of these vegetables. This would contribute to both preserving cultural heritage and conserving valuable indigenous flora. Such intervention would safeguard this sustainable and renewable resource in its pivotal socio-economic role in terms of rural food security as is substantiated by this study.
- Full Text:
- Date Issued: 2019
The suspended sediment yield and provenance of the Inxu River Catchment, Eastern Cape
- Authors: Nyamela, Namso
- Date: 2019
- Subjects: Suspended sediments -- South Africa -- Inxu River , Sedimentation and deposition -- South Africa -- Inxu River , Watershed management -- South Africa -- Inxu River , Erosion -- South Africa -- Inxu River , Soil erosion -- South Africa -- Inxu River
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/72150 , vital:30010
- Description: The excessive deposition and accumulation of suspended sediment leads to the degradation of water resources such as dams and rivers. For the purpose of preserving and protecting these resources, suspended sediment needs to be managed, and its management should be catchment-wide and catchment-specific. This is certainly the case for the eroded Inxu River Catchment, which has been identified as a major contributor of sediment to the planned Lalini Dam on the Tsitsa River (a tributary of the Mzimvubu River). Knowledge of suspended sediment flux and catchment sources will aid the design of relevant strategies to manage suspended sediment production. Suspended sediment flux was determined from sediment samples that were collected using citizen-based monitoring techniques at calendar- and event-based sampling frequency, along with discharges estimated using stage-discharge relationships. Sediment source areas were identified by determining the suspended sediment contribution from major sub-catchments and observing similarities in the characteristics of the sub-catchments that produced the most sediment. The Inxu River Catchment produced 5.5 t/ha/yr between 01 May 2016 and 30 April 2017. When compared to modelled sediment yield (7 t/ha/yr) from Le Roux et al. (2015), modelled output was not far off from the measured results and both measured and modelled results identified similar sediment source areas. Q-SSC relationships observed at the Inxu River Outlet indicated that sediment was eroded from local areas and sub-catchment sediment contribution confirmed that most of the sediment was from the lower Inxu River Catchment. Within this area, the Ncolosi and Qwakele River Sub-catchments were major sediment source areas and were subject to widespread gully erosion. Gully erosion was prominent on gentle slopes, foot slopes and valley-bottoms that have concave slope curvature and lie on the Tarkastad Formation. This Formation is associated with some of the most dispersive soils in the area. Moreover, the catchment is vulnerable to erosion due to cultivation and subsequent land abandonment, continuous grazing and dense rural populations. Other studies in the Mzimvubu catchment identified similar catchment characteristics that contribute to excessive erosion. This study has successfully measured sediment yield and identified areas that should be targeted and prioritised for rehabilitation within the Inxu River Catchment. The findings could be applied to a wider catchment scale. The study has successfully demonstrated the use of citizen-based monitoring and desktop techniques and has also identified some pitfalls of this approach.
- Full Text:
- Date Issued: 2019
The sustainability of small, medium and micro enterprises within the Nelson Mandela Bay Metropole
- Authors: Taft, Giovanni Sinclair
- Date: 2019
- Subjects: Small business -- South Africa -- Nelson Mandela Bay Municipality , Business enterprises -- South Africa -- Nelson Mandela Bay Municipality Construction industry -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43911 , vital:37083
- Description: This research evaluates the sustainability of Small, Medium and Micro Enterprises (SMMEs) within the Nelson Mandela Bay Metropole. It seeks to identify whether the current government initiatives offered by the SEDA, DTI and CIDB are effectively addressing the major issues faced by SMMEs in order for them to remain sustainable. It seeks clarity on whether large construction companies should also take responsibility for keeping SMMEs sustainable. The challenges faced by SMMEs include limited financial resources, poor access to markets, little infrastructure, complex labour laws, rampant crime, shortage of skills and bureaucratic systems (SEDA 2016). Government has made concerted efforts to address these challenges so that affirmative action and Broad Based Black Economic Empowerment (B-BBEE) objectives are met. This led to the establishment of the SEDA, DTI and CIDB. Despite the above governments efforts, SMMEs are still failing, and the factors that contribute to this need to be identified. Not being sustainable restricts economic growth and further widens the gap between the haves and havenots. The research methodology included interviews with contractors, consultants and SMME employees. Data collected were analysed to establish patterns that emerged, and triangulation was employed to consolidate the analysis. The process was conducted against the backdrop of a literature review that explored definitions, international reviews of SMMEs, the experience of SMMEs in developing and developed nations and an evaluation of government support to SMMEs. The research confirmed that SMME employees were generally inexperienced, had a poor understanding of the construction industry and endured huge financial constraints. Appointed Professional Consultants did not include them in project planning, while large appointed Construction companies needed to acknowledge the vital role that they played in the overall state economy. Finally, recommendations are made to develop and sustain SMMEs so that they take their rightful place in the Nelson Mandela Bay Metropole.
- Full Text:
- Date Issued: 2019
The synthesis, characterization, and application of peptide-capped magnetite nanoparticles for the targeting of cancer cells
- Authors: Hickson, Matthew Victor
- Date: 2019
- Subjects: Nanomedicine -- Research , Nanostructured materials Cancer -- Alternative treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40172 , vital:35965
- Description: In this study, a comparative analysis was performed upon three co-precipitation techniques for the synthesis of capped magnetite nanoparticles as to optimize the approach to the highest quality nanoparticles. Three techniques were applied whereby the capping agent either introduced before the stage of nanoparticle precipitation, simultaneously to the stage of precipitation, or after the stage of precipitation. The resultant nanoparticles were tested in terms of their size, dispersity, crystallinity, and magnetic characteristics. The three techniques gave nanoparticles of varying sizes and characteristics. Out of the three synthetic techniques, the post precipitation introduction method gave the highest quality nanoparticles in terms of size distribution, crystallinity and magnetic character. Three novel peptides were synthesized, incorporating amino acids to varying degrees. Structure was confirmed via IR and NMR spectroscopy. The peptides were studied potentiometrically to explore their acid nature and were explored computationally as to discern possible modes of interaction with the nanoparticles. These three peptides were further used in the capping of magnetite nanoparticles. For this set of nanoparticles, a higher synthesis temperature and larger iron content were used as to obtain larger nanoparticles. For the capping procedure, the post precipitation technique was used due to its previous positive results, once again yielding high quality nanoparticles with low size dispersity, high crystallinity, and high magnetic saturations. The nanoparticles were also seen to display positive zeta potentials, which are beneficial for cellular interactions. The peptides and peptide-capped nanoparticles were tested for biological activity against the healthy MCF-10A and cancerous MCF-7 cell lines. The MTT assay displayed increased proliferation for both the cell lines treated with the nanoparticles, while the peptide treatments decreased the MCF-10A cell lines proliferation and increased the MCF-7 proliferation. TEM analysis displayed nanoparticles in the cellular sections. An ICP-OES analysis on the cells showed that the capped nanoparticles of similar zeta potentials were seen to be taken up excessively by cells as compared to the uncapped. The nanoparticles of lower zeta potentials but higher L-glutamine content were taken up to a lesser degree.
- Full Text:
- Date Issued: 2019
The testing of natural and synthetic adjuvants to reduce herbicide-use and/or improve efficacy for the control of difficult-to-kill forest weeds
- Authors: Letaoana, Josias Tshukudu
- Date: 2019
- Subjects: Weeds -- Control , Invasive plants -- South Africa Invasive plants -- Ecology -- South Africa Forest ecology -- South Africa Forests and forestry -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40371 , vital:36153
- Description: Commercial plantations within South Africa occur across diverse sites in terms of climate and physiography. Intensive silvicultural practices (site preparation, fertilisation, weed management etc.) are carried out during the establishment phase to ensure that the actual production of timber approximates the potential capacity for a site. Of these silvicultural practices, weed management is regarded as one of the most important, as if not carried out, competition from weeds may negatively influence seedling survival, growth and uniformity. During the establishment phase (planting to canopy closure), weed management operations are generally effective, as most competing species are still in a juvenile growth phase, and easily controlled. Due to limited weed-tree competition following canopy closure, weed management operations are reduced to a single event per annum (if necessary). This reduction in weed management often allows semi-shade/shade tolerant species to become established, together with an increase in the effort required for their control. The South African forest industry makes use of independent international auditing bodies to ensure that plantations are managed in a responsible, yet sustainable manner. Integrated management practices are considered the most effective as they reduce reliance on a single control method, such as the use of herbicides alone. In conjunction with integrated management, would be the need to reduce the overall quantities of herbicides used, yet at the same time ensuring improved efficacy of those herbicides that are used. The testing of these two aspects (reduced herbicide use and/or improved efficacy) was conducted on three diverse weeds that occur during the post-establishment phase within South African plantations, namely: Setaria megaphylla (setaria); Hedychium gardnerianum (wild ginger); and Solanum mauritianum (bugweed). The management of these species is considered problematic, as current herbicides and rates of application are not always completely effective. Four trials were implemented in KwaZulu-Natal (Midlands). Setaria megaphylla (setaria): Two trials were initiated (spring and autumn), to test the seasonal application of glyphosate + adjuvant combinations for improved efficacy (and hence reduced herbicide-use). A control (no herbicide applied), Select® (clethodim cyclohexanedione 120 g a.i. ℓ-1), Roundup® (glyphosate isopropylamine salt 360 g a.i. ℓ-1), and five Roundup® + adjuvant combinations were tested in both trials. iii The five adjuvants included three natural and two synthetic products that exhibited different properties and modes of action. At both sites, the eight treatments were replicated three times and laid out in a randomised complete blocks design. Setaria cover was assessed prior to spraying (0 days relative to spraying), and then again after two months (64 days relative spraying), with absolute changes in regrowth analysed. Although the application of Roundup® on its own provided good control within both trials, complete setaria control could not be obtained. Select® and the tested adjuvants did not improve Roundup® efficacy at the rates at which they were applied. The application of Roundup® in autumn (x̄ = 5.2% live cover) was more effective than the spring application (x̄ = 8.5% live cover), indicating that future studies should focus more on a combination of a season of application and subsequent follow-up operations, rather than the role of the adjuvants tested. Hedychium gardnerianum (wild ginger): Currently no herbicides are registered for the control of wild ginger in South Africa. One trial was implemented to test the potential for the control of wild ginger with herbicides applied to the foliage, cut-stems or rhizomes. In addition to an untreated control (no herbicide applied), Roundup® (glyphosate isopropylamine salt 360 g a.i. ℓ-1 at 4%) was applied as a foliar spray, either alone or with five adjuvants (three natural and two synthetic adjuvants). Brush- Off® (metsulfuron-methyl 6 g a.i. ℓ-1) or Roundup® was also applied to the cut-stems and rhizomes. Herbicide phytotoxicity was assessed up till 229 days after treatment application in terms of mortality, reduced and/or abnormal growth (of the resprouts) and foliar necrosis and/or discolouration. Although the foliar application of Roundup® (alone or with adjuvants) resulted in limited phytotoxicity, these treatments were ineffective in terms of killing wild ginger. The application of Roundup® or Brush-Off® to either the cut rhizome or cut-stems were equally effective, however, the cut-stem application would be preferred due to the reduced effort required. Future studies should further optimize the application of Roundup® (lowered rates + adjuvants) to the cut-stems/rhizome. Solanum mauritianum (bugweed): One trial was implemented on a stand of mature bugweed (located within a pine stand). The potential to reduce rates and/or improve the efficacy of Garlon® (triclopyr butoxyethyl ester 480 g a.i. ℓ-1®) was tested through the use of four adjuvants (two natural and two synthetic products) when applied as either a cut-surface or basal bark application. Two untreated controls (cut-surface or iv basal bark) were included for comparative purposes. The trial consisted of a 2 x 5 factorial arrangement of 10 treatments replicated three times and laid out as a randomized complete block design (RCBD). Although the cut-surface treatments were more effective than the basal bark treatments, no treatment provided complete control of bugweed. Of the cut-surface treatments, Garlon® + Break-Thru® (polyether-polymethylsiloxane-copolymer 1 000 g ℓ-1), Garlon® + Orosorb® (orange oil 50 g ℓ-1), and Garlon® + Actipron Super® (mineral oil 820 g ℓ-1) were equally effective, with Garlon® + Nu-Film P® (poly-1-menthene 975 g ℓ-1) the least effective. As the adjuvants tested did not improve the efficacy of Garlon® at the rates applied, the use of the most cost-effective and environmentally acceptable product would be preferable. For effective long-term control of mature bugweed, a cutsurface application is advisable, together with follow-up operations required. The results from these trials indicate that for bugweed and setaria, the currently registered herbicides remain the products of choice, albeit not 100% effective on wellestablished plants. In addition, the use of the adjuvants tested did not improve herbicide efficacy (and hence the opportunity for reducing rates of application) for all three species tested. However, Roundup® or Brush-Off® applied to either the cut rhizome or cut-stems were equally effective in terms of wild ginger control, indicating an opportunity for further testing to optimise rates of application.
- Full Text:
- Date Issued: 2019
The time course changes in selected fatigue indicators in moderately trained participants
- Authors: Maduna, Bongani Cyprian
- Date: 2019
- Subjects: Athletes -- Health and hygiene , Fatigue , Athletes -- Physiology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76354 , vital:30553
- Description: Background: During daily physical activities, individuals will encounter some level of fatigue. This is especially true for athletes who exert their bodies to achieve superior performance and attempt to delay the onset of fatigue as far as possible. However, fatigue is a progressive process that is part of physical exercise. It is therefore, important to understand the various factors associated with fatigue. Objective: The purpose of this research project was to observe the changes in perceptual, physiological responses, and workload while participants performed a fatiguing cycling exercise task. In order to observe the aforementioned changes, one of the three variables, either perceptual, physiological responses or workload was kept constant, while the other two were observed as dependent variables. There were three test conditions, which permitted each variable to be kept constant in at least one of the three test conditions. Methods: Thirty-six apparently healthy university students were recruited for the study. The exercise was of 35 minute duration for each condition, with the data collection for HR (physiological response), RPE (perceptual response), and power output (workload) occurring at two minute intervals from the eighth minute until the thirtieth minute. The participants were required to perform a peak-power-output test in order set the relative performance ranges for each participant in order to elicit an observable fatigue response from all the participants. The three conditions included constant HR response, constant workload, and constant RPE response where each participant performed all of the above conditions on separate days.Results: The perceptual (RPE) response increased significantly (p<0.05) over time in all three test conditions, even under the constant RPE condition where it was expected to remain unchanged throughout the test duration. The HR response only demonstrated a significant (p<0.05) increase over time under the constant workload condition. Lastly, workload remained constant in all three testing conditions. Conclusion: Participants may be able to exercise for longer periods during sub-maximal exercise if they disregard the RPE warning response. In the current study, the RPE response illustrated that participants were being exerted more over time; however, the participants still had physiological and workload capacity to continue exercising. This research project has confirmed the fact that fatigue is a multifaceted phenomenon. Furthermore, it has been illustrated that RPE response alone as an indicator of fatigue onset may be misleading as participants did not breach the HR and workload steady state during the current research. Therefore, it may be more appropriate to assess fatigue onset through the assessment of more than one fatigue variable in order to ensure increased accuracy of the participants’ fatigue state assessment.
- Full Text:
- Date Issued: 2019
The use of filter-feeding fish (Clarias gariepinus and Oreochromis mossambicus) to remove microalgae from brewery effluent treatment ponds
- Authors: Nombembe, Lwazi
- Date: 2019
- Subjects: Clarias gariepinus -- Food , Mozambique tilapia -- Food , Water -- Purification -- South Africa , Algae -- Biotechnology -- South Africa , Microalgae -- Biotechnology-- South Africa , Brewery waste -- South Africa , Fish culture -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95745 , vital:31194
- Description: The removal of microalgae from high rate algal ponds (HRAP) in waste-water treatment systems remains a constraint to their use in effluent treatment systems. Conventional algae harvesting methods often have high energy demands, take up lots of space, are expensive to operate or are time consuming. The aim of the study was to determine if fish such as Clarias gariepinus and Oreochromis mossambicus, could be used to remove microalgae from waste-water treatment ponds (in the absence/presence of a flocculent in the former and in the absence or presence of pH moderation in the latter), and to investigate the subsequent influence of algae concentration on several water quality parameters. The age of Clarias gariepinus (3-12 months) had a positive relationship with the distance between gill rakers (98.27 to 163.34 μm; y=90.576+4.823*x: R²=0.549; F(1,18)=21.867; p<0.001) and these data suggested that these fish might be efficient at removing algae from HRAP effluent. However, this was not the case, even with flocculent application (but this result might have been confounded by very high pH readings, at which flocculation is less likely to occur). Oreochromis mossambicus removed some of this algae, but the pH was too high for tilapia culture. It was not possible to moderate the increase in pH by keeping tanks in the dark and thus preventing photosynthesis; but pH fluctuation in HRAP effluent could be moderated using CO2 sparging in an attempt to make the environment more hospitable for tilapia (the average pH that was moderated with CO2 was 8.43±0.06, whereas the unmoderated average was 10.65±0.06). However, pH moderation using CO2 sparging did not increase the rate at which algae were removed by O. mossambicus; rather, it compromised O2 concentration which dropped to 4.17±1.26 mg/l after five hours of CO2 sparging, whereas it increased to 20.50±1.41 mg/l in treatments with unadjusted pH over the same period. Fish can be used to remove algae from treated effluent, and Oreochromis mossambicus remains a recommended species. Future work needs to investigate moderating fluctuations in pH and O2 concentration to further facilitate this method of algae removal.
- Full Text:
- Date Issued: 2019
The use of image processing to determine cell defects in polycrystalline solar modules
- Authors: Banda, Peter
- Date: 2019
- Subjects: Polycrystals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/36573 , vital:33996
- Description: This research aims to use image processingtodetermine cell defects in polycrystalline solar modules. Image processing is a process of enhancing images for differentapplications. One domain that seems to not yet utilise the use of image processing, is photovoltaics. An increased use of fossil fuels is damaging the earth and a call to protect the earth has resulted in the emergence of pollutant-free technologies such as polycrystalline photovoltaic (PV) cells, which are connected to make up solar modules. However, defects often affect the performance of PV cells and consequently solar modules. Electroluminescence (EL) images are used to examine polycrystalline solar (PV) modules to determine if the modules are defective. The main research question that this research addressed is“How can an image processing technique be used to effectively identify defective polycrystalline PV cells from EL images of such cells?“. The experimental research methodology was used to address the main research question. The initial investigation into the problem revealed that certain sectors within industry, as well as the Physics Department at Nelson Mandela University(NMU), do not currently utiliseimage processing when examining EL images of solar modules. The current process is a tedious, manual process whereby solar modules are manually inspected. An analysis of the current processes enabled the identification of ways in which to automatically examine EL images of solar modules. An analysis of literatureprovided a better understanding of the different techniques that are used to examine solar modules, and it was identified how image processing can be applied to EL images. Further analysis of literatureprovided a better understanding of image processing and how image classification experiments using Deep Learning (DL) as an image processing technique can be used to address the main research question. The outcome of the experiments conducted in this research weredifferentadaptive models(LeNet, MobileNet, Xception)that can classify EL images of PV cellsaccording to known standardsused by the Physics Department at NMU. The known standards yielded four classes; normal, uncritical, critical and very critical, which were used for the classification of EL images of PV cells. The adaptive models were evaluated to obtain the precision, recall and F1–scoreof the models.The precession, recall, and F1–score were required to determine how effective the models were in identifying defective PV cells from EL images.The results indicated that an image processing technique canbe used to identify defective polycrystalline PV cells from EL images of such cells. However, further research needs to be conducted to improve the effectiveness of the adaptive models.
- Full Text:
- Date Issued: 2019
The use of insecticides and cultural control for the management of soil-borne pests during plantation establishment
- Authors: Siwela, Evidence Miyelani
- Date: 2019
- Subjects: Insecticides , Plant diseases Pests -- Control Pesticides
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43446 , vital:36882
- Description: Over the past decades, the productivity of South African forestry plantations has been negatively impacted by abiotic (fire, hail, wind, frost, drought etc.) and biotic factors (pests and diseases). The biotic component of insect pests and pathogens cause significant loss to the forestry industry and this affects the productivity, financial viability and long-term sustainability of plantations. Common establishment insect pests and diseases in South Africa include the pine bark beetle (Hylastes angustatus), cutworms (Agrotis spp), white grubs (Scarabaeidae larvae), rhizina root rot (Rhizina undulata), fusarium pitch canker (Fusarium circinatum), and pine dieback (Diplodia pinea). Soil-borne pests, mainly white grubs and cutworms can contribute to high seedling mortality following the re-establishment of eucalypts and wattle. Synthetic insecticides used for their control include alpha-cypermethrin, deltamethrin, and imidacloprid. However, all these insecticides are considered highly hazardous to the environment and/or human health and can no longer be considered for use in South African plantations. A need has therefore arisen to find and screen alternative products (synthetic and/or natural), that are not only environmentally safe for use, but also effective for the control of soil-borne pests during plantation establishment. In addition, these products can then be combined with other control mechanisms (such as cultural and biological control) to form an integrated pest management strategy. To address the above, a series of research trials were implemented with the outcomes discussed below. Two trials were implemented in KwaZulu-Natal (Demagtenberg) and Mpumalanga (Klipkraal) to determine if seedling size in combination with, or without an insecticide would result in improved survival of Pinus Patula. The main factors tested were Root Plug Volume (36 cm3 versus 103 cm3), Seedling Age (Standard [smaller] versus Older [larger]), and Pesticide application (untreated versus treated). Seedling quality was assessed in terms of Shoot:Root ratio, optimum Height (Ht in cm), and root collar diameter (Rcd in mm) before planting, with tree growth variates measured at planting, and then at regular intervals. The final measurements were taken at 7 years and 2 months for Demagtenberg and 5 years and 1 month for Klipkraal. For both trials, the Root Growth Potential (RGP) and total Plant Quality Index (PQI) indicated that Root Plug Volume 36 cm3 and Seedling Age (SA)_Standard (smaller) had a better Sturdiness ratio and Shoot:Root ratio compared to that of Root Plug Volume 103 cm3 and Seedling Age (SA)_Older (larger), with these benefits translated into improved field performance. The diameter at breast height (Dbh), Basal area (BA), Stocking and Volume indicated that SA_Standard and Root Plug Volume 36 cm3 resulted in better survival and growth than that of SA_Older (larger) seedlings and Root Plug Volume 103 cm3. The application of a Pesticide resulted in improved survival and growth at Klipkraal, but not at Demagtenberg. This indicated the presence of soil-borne pests at this site. In addition, the interaction between Pesticide application and SA_Standard resulted in a significantly larger BA than all other treatments only at Klipkraal, which indicates that both improved seedling quality and pesticides contributed to improved performance. One trial was established to Eucalyptus dunnii William Dunn at Umvoti North to investigate the effectiveness of the synthetic insecticides (deltamethrin, clothianidin, imidacloprid, imidacloprid + fertilizer, imidacloprid + clothianidin + fertilizer) and two natural products (azadirachtin and potassium silicate) for the control of soil-borne pests following planting. Groundline diameter (Gld), Height (Ht) and survival were assessed over a six-month period. Despite the selection of a site known to have a high incidence of soil-borne pests, few soil-borne pest were detected on the site for the trial duration, with no treatment differences observed for any of the tree growth variates. Significant differences were observed for foliar discolouration (possible phytotoxicity), however, these results were inconclusive as majority of the affected treatments (those that survived) showed full recovery. Three-month results from 12 eucalypt trials in KwaZulu-Natal, South Africa were compared to determine the benefits (including costs) of insecticides for the control of soil-borne pests. The 12 trials were selected to represent different physiographic regions, mainly within the warm temperate regions where white grubs and cutworms are likely to occur. Data for the trials were obtained from previous management research (published documents) and included six where mortality was the only variate assessed, with the Ht and Gld also assessed in the remaining six trials. There was a ≥ 2.5% increase in survival in seven of the 12 trials through the use of insecticides relative to the control, although only four of these seven were statistically significant. Of the 12 trials, the use of insecticides resulted in > 90% survival compared to the control at Mistley (93 versus 83%), Bloemendal (96 versus 62%) and Enon (burn) (96 versus 89%). At Garfield, Vulindlela, and Baynesfield, survival in both the treated and untreated treatments was below 90%, whereas both the treated and untreated treatments were above 90% at Rustig, Greenhill, Enon (slash), Umvoti, Dargle and Umvoti North. This data indicates that where soil-borne pests are present, the application of an insecticide is beneficial. Due to the costs associated with insecticide application, the challenge will be to determine which are high-risk sites that require treatment with an insecticide. Results from these trials indicate that on sites where soil-borne pests are present (and active), the application of insecticides is beneficial. However, even if present, the level of impact is less obvious, and possibly influenced by life cycle stage, site management and climate. The testing of alternative and less highly hazardous insecticides indicated the potential future use of insecticides in terms of limited seedling phytotoxicity (some of the products tested). To understand more fully the extent of their efficacy, these products would need to be re-tested again on sites where soil-borne pests are active. Optimum establishment practices, together with the planting of quality seedlings and application of an approved insecticide, will all contribute to improved survival and growth. Perhaps the biggest challenge will be the determination of soil pest activity, such that the application of pesticides can be limited to those sites where control is necessary..
- Full Text:
- Date Issued: 2019
The utility of facilities management in alleviating poor service delivery at Polokwane department of public works
- Authors: Sipungela, Nosipho Agreenett
- Date: 2019
- Subjects: Facility management , Public works -- South Africa Government productivity -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43457 , vital:36888
- Description: This study dealt with improving service delivery in the National Department of Public Works (NDPW) Polokwane Regional Office through facilities management (FM). It posits that FM can be usefully employed as an instrument to achieve integration of design, construction and FM. It argues that since FM encompasses the essential components of maintenance, refurbishment, reconfiguration and rehabilitation of accommodation it can be usefully utilised to ensure sustainability of government assets. An online data collection method was used to collect raw data from the selected sample. The sample population consisted of assistant directors, control works managers, works managers and administration officers within the FM of Polokwane regional office of the National Department of Public Works.The results show that performance management is not aligned to set service delivery standards and organisational objectives. Monitoring during the implementation of a project is sub- optimal and therefore does not ensure that services are rendered to the satisfaction of the client department. Moreover, there is no establised Management Information Systems (MIS) to keep records of information pertaining to infrastructure; conditional assessments; maintenance; the measurement of the quality of project output; the effectiveness of FM and the procurement policy; and the availability of skills and resources to execute the duties. The set hypotheses were tested by means of evaluation of data collected. The research finally presents a number of professional opinions and recommendations that could be considered to improve service delivery within the FM unit.
- Full Text:
- Date Issued: 2019
Time motion analyses of one-day international and twenty/20 matches and the development of a simulated batting protocol specifically designed for female cricket players
- Authors: Munro, Catherine
- Date: 2019
- Subjects: Women cricket players , Cricket -- Batting , Cricket -- Coaching , Cricket -- Physiological aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76342 , vital:30550
- Description: Background: Accurate and reliable in-game data is fundamental when designing effective batting training. A simulated batting protocol that could aid research and training has not been specifically designed for female cricketers because of a distinct lack of empirical in-game data for the women’s version of the game. Objective: The purpose of this study was to quantify the motion demands and run-breakdown of a century and T20 half-century for women’s cricket matches to establish a simulated batting protocol specifically designed for female batters. Method: Time-motion analyses of four one-day international and six T20 innings were conducted on international cricket matches played around the world between 2012 and 2017. The innings was divided into the bowling and batting innings. The ODI innings that met the criterion of 100 runs scored and T20 innings with scores above 50 runs were used in the run breakdown, which included scores from the top 10 countries ranked by the ICC. The time-motion analyses and century breakdown were utilised in the establishment of a simulated batting protocol. The simulated batting protocol for female batters was created/developed by utilising the method designed by Houghton et al., (2011), who developed the BATEX© protocol. Results: The time-motion analyses indicated that the mean duration of an ODI innings was 169 minutes. An over lasted 2.45 minutes, with 24.86 seconds between each delivery and 55 seconds between each over. When the bowling side changed to a new bowler, it was 1.12 minutes between overs. The mean score for the first power play in an ODI was 41 runs with 1.38 wickets being taken. The mean score during the second power play was 28 runs with 0.714 wickets being taken. The T20 bowling innings lasted 75.50 minutes, with an over lasting 2.52 minutes with 25.58 seconds between deliveries. The mean score in the T20 batting innings was 122 runs. During the power play, which lasted 24.35 minutes, 37 runs were scored with 1.45 wickets being taken. The simulated batting innings was then designed as four stages lasting the duration of a typical women’s century. Each stage was based on theoretical phases of play that may occur during a batting innings. Conclusion: The study indicated that the women’s game has different movement requirements compared to the men’s game in both the ODI and T20 formats. Further, the demands differ depending on the country that is playing. A training and research protocol specifically designed for female batters is an important outcome.
- Full Text:
- Date Issued: 2019
TiRiFiG, a graphical 3D kinematic modelling tool
- Authors: Twum, Samuel Nyarko
- Date: 2019
- Subjects: Tilted Ring Fitting GUI , Astronomy -- Observations , Galaxies -- Observations , Galaxies -- Measurement , Galaxies -- Measurement -- Data processing , Kinematics
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76409 , vital:30558
- Description: Galaxy kinematics is of crucial importance to understanding the structure, formation and evolution of galaxies. The studies of mass distributions giving rise to the missing mass problem, first raised by Zwicky (1933), give us an insight into dark matter distributions which are tightly linked to cosmology. Neutral hydrogen (H i) has been widely used as a tracer in the kinematic studies of galaxies. The Square Kilometre Array (SKA) and its precursors will produce large Hi datasets which will require kinematic modelling tools to extract kinematic parameters such as rotation curves. TiRiFiC (Józsa et al., 2007) is an example of such a tool for 3D kinematic modelling of resolved spectroscopic observations of rotating disks in terms of the tilted-ring model with varying complexities. TiRiFiC can be used to model a large number (20+) of parameters which are set in a configuration file (.def) for its execution. However, manually editing these parameters in a text editor is uncomfortable. In this work, we present TiRiFiG, Tilted Ring Fitting GUI, which is the graphical user interface that provides an easy way for parameter inputs to be modified in an interactive manner.
- Full Text:
- Date Issued: 2019
Towards defining the tipping point of tolerance to CO2-induced ocean acidification for the growth, development and metabolism of larval dusky kob Argyrosomus japonicus (Pisces: Sciaenidae)
- Authors: Mpopetsi, Pule Peter
- Date: 2019
- Subjects: Argyrosomus japonicus , Argyrosomus , Argyrosomus japonicus -- Larvae , Argyrosomus -- Larvae -- Effect of water acidification on , Argyrosomus japonicus -- Larvae -- Nutrition , Argyrosomus -- Larvae -- Nutrition , Ocean acidification
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/71602 , vital:29924
- Description: Increased CO2 production and the consequent ocean acidification (OA) have been identified as one of the greatest threats to both calcifying and non-calcifying marine organisms. Traditionally, marine fishes, as non-calcifying organisms, were considered to have a higher tolerance to near-future OA conditions owing to their well-developed ion regulatory mechanisms. However, recent studies provide evidence to suggest that they may not be as resilient to near-future OA conditions as previously thought. In addition, earlier life stages of marine fishes are thought to be less tolerant than juveniles and adults of the same species as they lack well-developed ion regulatory mechanisms for maintaining homeostasis. This study follows up on previous studies examining the effects of near-future OA on larval Argyrosomus japonicus, an estuarine-dependent marine fish species, in order to identify the tipping point of tolerance for the larvae of this species. These previous studies showed that elevated pCO2, predicted for the year 2100, had negative effects on growth, development and metabolism and ultimately, survival of larval A. japonicus from post-flexion stage. Larval A. japonicus in the present study were reared from egg up to 22 DAH (days after hatching) under three treatments. The three treatments, (pCO2 353 μatm; pH 8.03), (pCO2 451 μatm; pH 7.93) and (pCO2 602 μatm; pH 7.83) corresponded to levels predicted to occur in year 2050, 2068 and 2090 respectively under the Intergovernmental Panel on Climate Change (IPCC) Representative Concentration Pathways (IPCC RCP) 8.5 model. Size-at-hatch, growth, development and metabolic responses (standard and active metabolic rates and metabolic scope) were assessed and compared between the three treatments throughout the rearing period. Five earlier larval life stages (hatchling – flexion/post-flexion) were identified by the end of the experiment. There were no significant differences in size-at-hatch (P > 0.05), development or the active metabolic (P > 0.05) or metabolic scope (P > 0.05) of fish in the three treatments throughout the study. However, the standard metabolic rate was significantly higher in the year 2068 treatment but only at the flexion/post-flexion stage which could be attributed to differences in developmental rates (including the development of the gills) between the 2068 and the other two treatments. Overall, the metabolic scope was narrowest in the 2090 treatment, but varied according to life stage. Although not significantly different, metabolic scope in the 2090 treatment was noticeably lower at the flexion stage compared to the other two treatments, and the development appeared slower, suggesting that this could be the stage most prone to OA. The study concluded that, in isolation, OA levels predicted to occur between 2050 and 2090 will not negatively affect size-at-hatch, growth, development, and metabolic responses of larval A. japonicus up to 22 DAH (flexion/post-flexion stage). Taken together with the previous studies of the same species, the tipping point of tolerance (where negative impacts will begin) in larvae of the species appears to be between the years 2090 and 2100.
- Full Text:
- Date Issued: 2019
Towards understanding and mitigating attacks leveraging zero-day exploits
- Authors: Smit, Liam
- Date: 2019
- Subjects: Computer crimes -- Prevention , Data protection , Hacking , Computer security , Computer networks -- Security measures , Computers -- Access control , Malware (Computer software)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115718 , vital:34218
- Description: Zero-day vulnerabilities are unknown and therefore not addressed with the result that they can be exploited by attackers to gain unauthorised system access. In order to understand and mitigate against attacks leveraging zero-days or unknown techniques, it is necessary to study the vulnerabilities, exploits and attacks that make use of them. In recent years there have been a number of leaks publishing such attacks using various methods to exploit vulnerabilities. This research seeks to understand what types of vulnerabilities exist, why and how these are exploited, and how to defend against such attacks by either mitigating the vulnerabilities or the method / process of exploiting them. By moving beyond merely remedying the vulnerabilities to defences that are able to prevent or detect the actions taken by attackers, the security of the information system will be better positioned to deal with future unknown threats. An interesting finding is how attackers exploit moving beyond the observable bounds to circumvent security defences, for example, compromising syslog servers, or going down to lower system rings to gain access. However, defenders can counter this by employing defences that are external to the system preventing attackers from disabling them or removing collected evidence after gaining system access. Attackers are able to defeat air-gaps via the leakage of electromagnetic radiation as well as misdirect attribution by planting false artefacts for forensic analysis and attacking from third party information systems. They analyse the methods of other attackers to learn new techniques. An example of this is the Umbrage project whereby malware is analysed to decide whether it should be implemented as a proof of concept. Another important finding is that attackers respect defence mechanisms such as: remote syslog (e.g. firewall), core dump files, database auditing, and Tripwire (e.g. SlyHeretic). These defences all have the potential to result in the attacker being discovered. Attackers must either negate the defence mechanism or find unprotected targets. Defenders can use technologies such as encryption to defend against interception and man-in-the-middle attacks. They can also employ honeytokens and honeypots to alarm misdirect, slow down and learn from attackers. By employing various tactics defenders are able to increase their chance of detecting and time to react to attacks, even those exploiting hitherto unknown vulnerabilities. To summarize the information presented in this thesis and to show the practical importance thereof, an examination is presented of the NSA's network intrusion of the SWIFT organisation. It shows that the firewalls were exploited with remote code execution zerodays. This attack has a striking parallel in the approach used in the recent VPNFilter malware. If nothing else, the leaks provide information to other actors on how to attack and what to avoid. However, by studying state actors, we can gain insight into what other actors with fewer resources can do in the future.
- Full Text:
- Date Issued: 2019