M3: Mining Mini-Halos with MeerKAT
- Authors: Trehaeven, Keegan Somerset
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424754 , vital:72181
- Description: This work aims to showcase the MeerKAT telescope’s capabilities and related calibration and imaging software in studying the emission of radio mini-halos. These diffuse radio synchrotron sources surround a Brightest Cluster Galaxy (BCG) in relatively relaxed clusters out to a few 100 kpc in size. They are difficult to image because of their relatively low surface brightness and small angular size. Hence, they could not be studied in great detail by previous generations of radio telescopes and much about their nature, particularly the exact production mechanism, is not yet fully understood. Thus, for the first time, MeerKAT observed a sample of five galaxy clusters to investigate the central radio mini-halo in each. Studying these sources requires the deepest images generated from the data and the effective subtraction of any projected sources obscuring or contaminating the underlying diffuse emission. Therefore, I describe the data reduction used to create third-generation calibrated, primary beam corrected, point source subtracted Stokes I L-band continuum images of these clusters. For first- and second-generation calibration, I use the CARACal pipeline, which implements software optimised explicitly for MeerKAT data. For third-generation calibration, I use the faceted approach of killMS and DDFacet, and then I perform visibility-plane point source subtraction to disentangle the compact and diffuse emissions. I then measured the size, flux density, in-band spectral properties, and radio power of the central mini-halos. I present the first new mini-halo detection by MeerKAT (MACS J2140.2-2339, Trehaeven et al. accepted), the first spectral index maps of these mini-halos, which show very interesting distributions, and a ∼100 kpc II southern extension to the ACO 3444 mini-halo previously unseen in archival VLA data. Thereafter, I present a multi-wavelength case study for two complementary mini-halos from our sample and show via a radio-to-X-ray spatial correlation test that they might be caused by different particle (re)-acceleration mechanisms. Through these initial science results, I have shown that future observations of radio mini-halos with MeerKAT are an exciting prospect that can lead to a better understanding of the fundamental physics behind these sources. , Thesis (MSc) -- Faculty of Science, Physics and Electronics, 2023
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Assessing the density and distribution of spotted hyaenas (Crocuta crocuta) in Hluhluwe–iMfolozi Park, KwaZulu-Natal, South Africa
- Authors: Roberts, Peter Jean
- Date: 2022-04-06
- Subjects: Spotted hyena Home range South Africa Hluhluwe Game Reserve , Spotted hyena Habitat South Africa Hluhluwe Game Reserve , Animal population density South Africa Hluhluwe Game Reserve , Scouting cameras , Home range (Animal geography) , Spatially-explicit mark recapture (SECR)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/292681 , vital:57006
- Description: Protected areas are becoming increasingly isolated refugia for large carnivores and are critical for their survival. Spotted hyaenas (Crocuta crocuta) have, for centuries, been ‘managed’ as problem causing animals and their conservation has been largely overlooked. To preserve a population, it is paramount to understand its distribution and abundance through reliable and cost-effective monitoring techniques. My study estimated the density of spotted hyaenas and their use of space in Hluhluwe–iMfolozi Park (HiP), South Africa. I compared camera trap by-catch data and call-up surveys between 2013–2018 to assess spotted hyaena densities. The camera trap data estimated an average of 16.72 (SD: ±2.22) hyaenas per 100 km2 between 2013–2018, with an annual estimated high of 19.01 in 2018 and a low of 12.77 in 2015. The call-up surveys consistently produced lower estimates than those obtained from the camera trap data. These results highlight the importance of calibrating the response probability factor for call-up surveys to maintain precision. The space use of spotted hyaenas was analysed using the photo-capture data obtained during the same six-year period, to produce individual 100% Minimum Convex Polygon’s (MCPs). Seven clan territories were identified from individual female home ranges that overlapped by more than 66% of their MCPs. Territory sizes were similar to historical estimates for the park, with averages of 13.96 (SD: ±6.48) km2 in Hluhluwe and 34.61 (SD: ±23.87) km2 in iMfolozi. My study successfully used by-catch camera data to calculate annual density estimates and investigate the spatial use patterns for spotted hyaenas in HiP. I demonstrate that this approach is cost-effective and reliable for calculating density estimates. Conservation practitioners should take heed of the advancements in technology and analytical capacity now available to them to improve monitoring efforts. My study specifically calls for collaborative efforts to use existing camera trap data to improve regional estimates and population trends of spotted hyaenas across their range. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2022
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The role of a national system of innovation in facilitating development in South Africa from a comparative BRICS perspective
- Authors: Sibhukwana, Andiswa
- Date: 2022-04-06
- Subjects: BRIC countries , Technological innovations Economic aspects South Africa , Economic development South Africa , Economics Mathematical models , Neoclassical school of economics , South Africa Economic conditions , South Africa Economic policy , National systems of innovation
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/284616 , vital:56079
- Description: The aim of the dissertation was to investigate whether the adoption of a national system of innovation has helped facilitate development in South Africa from a comparative BRICS perspective. South Africa has an expanding focus on science and technology, as per the Science and Technology White Paper (1996). There appeared to be innovation that had left out much of the citizenry. There continued to be poverty, inequality, and joblessness. The study aimed to understand how the NSI approach could be used to foster inclusive and transformative development. The study used a mixed-methods approach. The qualitative aspect of the research focused on an innovation and public policy study which assessed the various policies and initiatives implemented in each of the BRICS countries to drive innovation and foster development. The qualitative aspect of the study found that the innovation paradigm required governments to adopt a more holistic approach to public policy design and analysis. The quantitative aspect of the research focused on a trend, correlation, and regression analysis. The trend analysis revealed that China and Brazil increased their allocation of resources towards R&D compared to the other countries. Brazil is regarded as a social investment state, while China is a developmental state: this means the state plays an extraordinarily strong coordinative and financing role in the NSI. On the other hand, the correlation matrix for South Africa revealed a statistically significant positive linear association between various NSI indicators and human development. This suggested that the innovation benefits are trickling down to the general citizenry. In essence the study articulated key elements of the understanding of current and potential impacts of technological change in productivity and growth, employment and inequality that can be used for policy making. , Thesis (MEcon) -- Faculty of Commerce, Economics and Economic History, 2022
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Inkcitha nzila nobomi obutsha (The release of the widow and life after mourning): Xhosa widows and citizenship
- Authors: Jimlongo, Gcotyelwa Nomxolisi
- Date: 2021-10-29
- Subjects: Widows South Africa Eastern Cape , Women, Black South Africa Eastern Cape , Xhosa (African people) South Africa Eastern Cape , Widows Social conditions , Widowhood Psychological aspects South Africa Eastern Cape , Widowhood Economic aspects South Africa Eastern Cape , Widowhood Social aspects South Africa Eastern Cape , Mourning customs South Africa Eastern Cape , Feminist economics South Africa Eastern Cape
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192220 , vital:45206
- Description: This study examines the everyday conceptions and navigations of citizenship by Xhosa widows. It examines widows’ own understandings and experiences of citizenship once the official mourning period, known amongst amaXhosa as ukuzila, has ended. The study draws from 14 interviews with Xhosa widows from the Amalinda, Tsholomnqa, Mdantsane, Magcumeni, KwaNonkcampa, and Dimbaza areas in the Eastern Cape, South Africa. This thesis contextualises claims to widowhood in the context of democratic South Africa, and the various ways in which widowed women conceptualise their lives after ukuzila. While ukuzila itself is written about in the literature, the contentious claims to widowhood and the ways in which women come to make sense of their lives in the post-mourning period remains largely unexplored. Interviews were conducted with women who had undertaken customary and/or civil marriages, had divorced or separated from their partners, or had cohabited. They reveal that widowhood is tenuous and as such, remains contested and contestable. The study demonstrates that much of the claims to widowhood are made because of the undeniable labour that women perform during the partnerships, where they are the primary economic providers. The study shows that whether in the formal and informal sector, women have been central in building the economic livelihoods of their families. In the post-mourning period, the theme of ukuhlala (to stay) that is articulated by widows, shows that they choose to remain in their marital homes to protect what they have laboured for. The findings demonstrate that the key to ‘good’ widowhood is intricately linked to ‘good’ motherhood. For Xhosa widows, much of their decision-making, and livelihood strategies, rests on how they craft good livelihoods for their families. These include a negotiation of feminist economies with woman-centred networks, a reliance on spirituality, as well as negotiations for dignity and respect within the homestead through the protection and maintenance of what they have built over the years. , Thesis (MA) -- Faculty of Humanities, Political and International Studies, 2021
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Echogenic liposomes for ultrasound-triggered drug delivery
- Authors: Izuchukwu, Ezekiel Charles
- Date: 2021-10
- Subjects: Liposomes , Drug delivery systems , Colon (Anatomy) Cancer Treatment , Transmission electron microscopy , Fourier transform infrared spectroscopy , Liquid chromatography , Echogenic liposomes , Ultrasound-triggered drug delivery
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/10962/188997 , vital:44805
- Description: Colorectal cancer is one of common cancers worldwide. It is the third most diagnosed cancer and the second leading cause of death. The use of 5-fluorouracil (5-FU) alone or in a chemotherapy regime has been the effective treatment of colorectal cancer patients. The efficacy of 5-FU in colorectal cancer treatment is significantly limited by drug resistance, gastrointestinal, and bone marrow toxicity through high-level expression of thymidylate synthase, justifying a need to improve its therapeutic index. Liposomes are colloidal membranes comprising of one or more lipid bilayers enclosing an aqueous core. They have been used to improve the therapeutic index of many anti-cancer drugs by changing drug absorption, elongating biological half-life, reducing metabolism, and reducing toxicity to healthy tissues. Echogenic liposomes are specifically designed to respond to external triggering like ultrasound stimulation by entrapping a gas or an emulsion that can vaporize. A liposome's unique property is that it can entrap both hydrophobic and hydrophilic substances simultaneously in the lipid bilayer and the aqueous core, respectively. These stimuli-responsive liposomes can be triggered externally with ultrasound, to release the chemotherapeutic cargo only at the required site. This research aims to formulate echogenic liposomes encapsulating 5-FU for potential ultrasound triggered release (echogenic). Liposome formulations wereprepared with lipid composition of crude soybean lecithin and cholesterol by thin-filmhydration method and the drug was passively loaded in the formulation. The 5-FU loadedliposomes were evaluated by dynamic light scattering (DLS) for particle size, polydispersityindex, and zeta potential and transmission electron microscopy (TEM) for morphology.Encapsulated liposomal formulations were also evaluated using physicochemical techniquesincluding thermogravimetric analysis (TGA), differential scanning calorimetry (DSC),Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Theencapsulation efficiency and release kinetics were studied using a validated high-performanceliquid chromatography (HPLC) method. Echogenic properties were explored by entrapping abiocompatible gas (argon) at the same time as the drug (5-FU) using a pressure/freezemethodology. The liposomal formulations were typically spherical with a size of about 150 nmand encapsulation efficiency of 62%. Low-frequency ultrasound (20 kHz) was used to triggerthe drug release from the complete formulation at 10%, 15%, and 20% amplitude and exposuretime of 5 min and 10 min. The rate of drug release from the nano-carrier was a function of theultrasound amplitude and exposure time and reached a maximum of 65% release under theconditions investigated. The cumulative release was investigated, with and without theapplication of ultrasound. It was demonstrated that the application of ultrasound resulted in complete release (99%) after 12 h while this dropped to 70% without ultrasound. These results are encouraging for optimizing ultrasound parameters for triggered and controlled release of the 5-FU, for conditions such as the management of cancer where low-power ultrasound can be applied. , Thesis (MSc) -- Faculty of Science, Chemistry, 2021
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Investigating water knowledge flow to communities
- Authors: Burt, Jane C , Berold, Robert
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433013 , vital:72923 , xlink:href="https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/KV%20288-11.pdf"
- Description: Those of us who work in water resource management have found that very few knowledge/research resources are accessible to most people. This happens because resources are not disseminated properly (or at all), or because they are inappropriately technicist, or because potential readers are hampered by low education. What is the best way to make water research accessible to as many people as possible and especially to people whose lives would be affected by the research? In the early 1980s an attempt was made to address this issue when Robert Berold edited People's Workbook (EDA 1981), a user-friendly book that presented basic technical information for rural people – not only on water, but also on agriculture, health, building construction, and income generation. The book included real-life interviews, and was disseminated by rural fieldworkers. Perhaps because there was nothing like it at the time, it was enormously popular.
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