Modernisation and extension of InetVis: a network security data visualisation tool
- Authors: Johnson, Yestin
- Date: 2019
- Subjects: Data visualization , InetVis (Application software)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/69223 , vital:29447
- Description: This research undertook an investigation in digital archaeology, modernisation, and revitalisation of the InetVis software application, developed at Rhodes University in 2007. InetVis allows users to visualise network traffic in an interactive 3D scatter plot. This software is based on the idea of the Spinning Cube of Potential Doom, introduced by Stephen Lau. The original InetVis research project aimed to extend this concept and implementation, specifically for use in analysing network telescope traffic. The InetVis source code was examined and ported to run on modern operating systems. The porting process involved updating the UI framework, Qt, from version 3 to 5, as well as adding support for 64-bit compilation. This research extended its usefulness with the implementation of new, high-value, features and improvements. The most notable new features include the addition of a general settings framework, improved screenshot generation, automated visualisation modes, new keyboard shortcuts, and support for building and running InetVis on macOS. Additional features and improvements were identified for future work. These consist of support for a plug-in architecture and an extended heads-up display. A user survey was then conducted, determining that respondents found InetVis to be easy to use and useful. The user survey also allowed the identification of new and proposed features that the respondents found to be most useful. At this point, no other tool offers the simplicity and user-friendliness of InetVis when it comes to the analysis of network packet captures, especially those from network telescopes.
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- Date Issued: 2019
Narratives and home: remembering an almost forgotten walk
- Authors: Bezuidenhout, Natasha Belinda
- Date: 2019
- Subjects: Home in literature , Home in art , Artists -- South Africa
- Language: English
- Type: text , Thesis , Masters , MFA
- Identifier: http://hdl.handle.net/10962/115039 , vital:34072
- Description: The title of my exhibition Bittersoet alludes to the self-exploratory nature of my practice, as I interrogate the personal memories associated with objects that characterise the relationship between myself and my mother (mamma). This supporting document, Narratives and Home: Remembering an almost forgotten walk, considers the key conceptual concerns informing my practice. In this mini-thesis, I address the question: ‘What is a home?’. Drawing from my own Fine Art Practice, I explore how home can be examined as a product of the imagination, rather than only as a physical place. I consider how ‘home’ is constructed as the primary objective within an ideological framework defined by history, memory and narrative. Engaging beyond the idea of ‘home’ as a fixed structure or place, I examine the idea of ‘home’ as something fluid that is negotiated and defined by the interaction between objects and language. It is concerned with dialectics of memory and narrative as they pertain directly to an experience of both searching for and reimagining home through metaphorical representations. In particular, I explore how home can be seen as equally familiar and unfamiliar, existing in-between, always changing, never fixed, rather in a constant state of flux. The concept of home is addressed in a dialogical process by using Afrikaans as my mother tongue, I narrate informal conversations between myself and my mother. These conversations transform and expand into hybrid words, memories and narratives to form a layered continuous dialogue between my practice and research. This notion relates to exploring oneself and the ‘fictions’ of the past. The self being fundamental to the individual comprehension of both ‘place’ and ‘space’.
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- Date Issued: 2019
National debt and sovereign credit ratings
- Authors: Orsmond, Daniel
- Date: 2019
- Subjects: Debts, Public -- South Africa , Credit ratings -- South Africa , Gross domestic product -- Africa , Inflation (Finance) -- Africa , Economic development -- South Africa , Economic history , Macroeconomics , Moody's Investors Service , Standard and Poor's Ratings Services , Fitch Ratings (Firm)
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/115160 , vital:34083
- Description: In recent years South Africa’s foreign and local denominated debt has been downgraded by the three major global credit agencies, Moody’s, Standard and Poor’s (S&P) and Fitch. The foreign debt has been downgraded to speculative grade or ‘junk’ status by all three agencies. Local debt has been downgraded to ‘junk’ by S& P and Fitch, but Moody’s currently maintains local debt at the lowest level of investment grade. Many economists believe that South Africa’s rapidly rising debt levels are the major contributor to the decisions to downgrade South Africa’s debt. Yet many countries with higher levels of debt continue to be rated investment grade. Clearly, factors other than the actual level of debt are important in determining the credit rating agencies’ rating decisions. The literature suggests several variables are important in determining a country’s sovereign credit rating. These variables include not just the ratio of government debt to gross domestic product, but also a country’s real growth rate, inflation, gross domestic product per capita, external balance to gross domestic product, default history and the level of economic development. In examining the proposition that it is not a country’s debt level per se that matters, but rather the dynamics surrounding that debt, this research also includes three additional variables that are not usually mentioned in the literature. These, based on van der Merwe (1993), are the real GDP growth rate less the real interest rate, the ratio of the fiscal balance to GDP, and the ratio of government interest payments to government expenditure. The purpose of this addition is to examine whether rather than a country’s debt level (debt to GDP variable), it is the sustainability of a country’s ability to service debt, as indicated by the three additional ‘debt dynamic’ variables, that is most important when determining sovereign credit ratings. Panel data analysis for a sample of 12 countries over the period 1996Q1 to 2017Q4 indicates that of the broad macroeconomic variables mentioned in the literature, government debt to GDP, the real growth rate, inflation (cpi), and default history are all statistically significant, with the coefficients having the correct signs in all specification of the model, with the exception of the real growth rate in Models 2 and 3. With regards to the debt dynamic variables, the real growth rate less the real interest rate, as well as the interest payments to government expenditure variables are found to be significant determinants of sovereign credit ratings. Thus, the findings of the research suggest that the level of debt alone is an inadequate determinant of sovereign credit ratings. The dynamics of debt along with other macroeconomic variables are also important determinants of a country’s credit rating. Concerning policy recommendations, it is evident that debt sustainability is important for sovereign credit ratings. Evidence of the direct importance of economic growth in determining credit ratings is mixed, but growth is a key driver of debt dynamics variables and therefore of ratings. This suggests that policy should focus on stimulating growth to reduce the gap between real growth and real interest rates as well as increasing the denominator of the debt to GDP ratio and increase the size of the tax base, which would improve government’s ability to service the interest payments on its debt.
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- Date Issued: 2019
Ndonakele
- Authors: Ngcelwane, Ayabulela
- Date: 2019
- Subjects: Xhosa fiction , Xhosa poetry
- Language: English , Xhosa
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/92721 , vital:30742
- Description: Le thisisi yingqokelela yemibongo egxile kwimingeni ejamelene noluntu kwimimandla efana neelokishi. Unobangela wale mingeni yintswelo-ngqesho, ukungafumani zindlu, ubundlobongela, isimo sezepolitiki, njalo-njalo. Imisebenzi kaRonnie Kasrils ngakumbi kwincwadi yakhe ethi A simple man, uRustum Siyongwana – Ubulumko bezinja uS. S. Mema – Umnxeba Wobomi, nezinye, zibe nefuthe kakhulu kule thisisi. Indlela abasebenzisa ngayo ulwimi lwemihla ngemihla, maxawambi bade basebenzise nesakhono esisetyenziswa ezintsomini ezifana nokusebenzisa abalinganiswa abazizilwanyana bekwekwa umba onobuzaza. Injongo yalo msebenzi kukugqamisa ukubaluleka kwentlalontle yoluntu, nokuvuselela isazela koongxowa ayibotshwa. Yiyo loo nto kuzanywe kangangoko ukusetyenziswa ulwimi olunokufikeleleka nakubani na. , English and Xhoxa versions provided for dual language submission
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- Date Issued: 2019
Ndoxoza mphini wumbi!
- Authors: Saki, Sandile Dudu
- Date: 2019
- Subjects: South African fiction (English)
- Language: English , Xhosa
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/92605 , vital:30741
- Description: My English half-thesis comprises semi-autobiographical short stories based on my own lived and observed experiences of patriarchal township life, but told through the eyes of others, often those who find themselves victims of societal ills and cruel injustices. The stories deal with issues ranging from rape culture, intimate femicide, social patriarchy and the vulnerability of women, children and people living with disabilities in such settings. Refusing didacticism, I seek to voice the complexity, bravery and beauty of my characters. I draw influence from Joel Matlou’s simple narration of the small details of daily life, Can Themba’s ability to find humour in the everyday, Chimamanda Ngozi Adichie’s contemporary sass and Irenosen Okojie’s unconventional, subtle and deeply enigmatic approach to storytelling. , Le thisisi yingqokelela yemibongo enesingqi nefuthe endilincance kubabhali endihlangene nabo kwezi zifundo endingabala kubo uMxolisi Nyezwa, Rustum Kozain nabanye. Injongo yale thisisi kukonwabisa; ukucebisa mhlawumbi ukuthungulula iintongo emva kobentlombe. Maxa wambi ikukukhahlela nakwabo baye banegalelo kwizinto-yinto zokuhlala ngakumbi iimvumi zikaMasikhandi ezifana noMlindelwa ‘Inkunz’ emdaka’ Mralatya owaziwa njengovulindlela kaMasikhandi kwisizwe sakwaXhosa siphela. Bakho ke ababhali abasingqi sabo sindithimbileyo, naba bugcisa ndibuthandileyo endingabalula kubo uMzwandile Matiwana, M. S. Mlandu, Fundile Majola, John Solilo, J. J. R Jolobe kunye noS. E. K. Mqhayi. Liyavakala ifuthe labo kule mibongo, ngakumbi isingqi nokusetyenziswa kolwimi. , English and Xhosa versions provided for dual language submission
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- Date Issued: 2019
Negotiating spaces, constructing identities and consuming symbolic resources: examining the complex interplay between identity formation, context and media consumption amongst black South African students at Rhodes University
- Authors: Willetts, Luke
- Date: 2019
- Subjects: Mass media -- Psychological aspects -- South Africa -- Makhanda , Mass media -- Social aspects -- South Africa -- Makhanda , Mass media -- Sociological aspects -- South Africa -- Makhanda , Mass media and culture -- South Africa , Mass media and race relations -- South Africa , Social movements -- South Africa -- Makhanda , Student movements -- South Africa -- Makhanda , Male college students -- South Africa -- Makhanda , Rhodes University -- Students -- Attitudes
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/95207 , vital:31127
- Description: This thesis has looked at the complex interplay between media consumption and identity formation amongst a group of black South African male students within the context of a racially homogenous communal viewing area located on the Rhodes University campus during the #FMF protests in 2016. Using qualitative research methods the study concluded that the group context of communal viewing helped the students structure and make sense of their daily lives. They actively divorced themselves from the main student populace in an attempt to escape lived experiences of a repressive institutional culture expressed through the university’s monolingual language policies, aesthetics and course material. These students embodied the characteristics of a diasporic community characterised by displacement, dispersal and the continuous re-articulation of differences across contradictory social, cultural and economic contexts. They grappled with an alienating environment by creating a safe space for cultural reproduction aided by the communal consumption of local television programmes. Preferences for local content broadcast in African languages were shaped by a linguistic marginalisation experienced on the Rhodes campus. The politicisation of the context through #FMF in turn politicised the students’ subjectivities leading to a need to be informed of the movement’s progression through evening news broadcasts. Discussions around campus life were dominated by #FMF and the collective experiences of marginalisation in and from the university space. Communal viewing of local television shows allowed this group of students to transcend decades of essentialised African ethnic divisions bringing forward a group identity premised on a lived hegemony signified by blackness.
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- Date Issued: 2019
Nonlinear optical responses of targeted phthalocyanines when conjugated with nanomaterials or fabricated into polymer thin films
- Authors: Nwaji, Njemuwa Njoku
- Date: 2019
- Subjects: Electrochemistry , Phthalocyanines , Nanoparticles , Bioconjugates , Thin films , Polymers , Nonlinear optics , Nonlinear optical spectroscopy , Nanostructured materials , Raman effect
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71625 , vital:29926
- Description: A number of zinc, gallium and indium metallophthalocyanines (MPcs) with diverse substituents have been synthesized and characterized using various characterization tools such as proton nuclear magnetic resonance (1HNMR), matrix assisted laser desorption time of flight (MALDI-TOF) mass spectrometry, Fourier-transformed infra-red (FT-IR), Ultraviolet-visible (Uv-vis) spectrophotometry, magnetic circular dichroism and CHNS elemental analysis. The time dependent density functional theory was employed to probe the origin of spectroscopic information in these complexes. Complexes with gallium and indium as central metal showed higher triplet quantum yield compared to the zinc derivatives. Some of the MPcs were covalently linked to nanomaterials such as CdTe, CdTeSe, CdTeSe/ZnO, graphene quantum dots (GQDs) as well as metallic gold (AuNPs) and silver (AgNPs) nanoparticles. Others were either surface assembled onto AuNPs and AgNPs or embedded into polystyrene as polymer source. The phthalocyanine-nanomaterial composites (Pc-NMCs) were characterized with FT-IR, UV-visible spectrophotometry, transmission electron microscopy (TEM), dynamic light scattering (DLS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD). The thickness of the thin films was determined by utilization of the knife edge attachment of the A Bruker D8 Discover X-ray diffraction. The optical limiting properties (using the open-aperture Z-scan technique) of the MPcs and the Pc-NMCs were investigated. The investigated MPcs complexes generally showed good optical limiting properties. The nonlinear optical response of the MPcs were improved in the presence of nanomaterials such as the semiconductor quantum dots (SQDs), graphene quantum dots (GQDs) as well as metallic AuNPs and AgNPs with MPc-QDs showing the best optical limiting behavior. The optical limiting properties of the MPcs were greatly enhanced in the presence of polymer thin films.
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- Date Issued: 2019
Observing cosmic reionization with PAPER: polarized foreground simulations and all sky images
- Authors: Nunhokee, Chuneeta Devi
- Date: 2019
- Subjects: Cosmic background radiation , Astronomy -- Observations , Epoch of reionization -- Research , Hydrogen -- Spectra , Radio interferometers
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/68203 , vital:29218
- Description: The Donald C. Backer Precision Array to Probe the Epoch of Reionization (PAPER, Parsons et al., 2010) was built with an aim to detect the redshifted 21 cm Hydrogen line, which is likely the best probe of thermal evolution of the intergalactic medium and reionization of neutral Hydrogen in our Universe. Observations of the 21 cm signal are challenged by bright astrophysical foregrounds and systematics that require precise modeling in order to extract the cosmological signal. In particular, the instrumental leakage of polarized foregrounds may contaminate the 21 cm power spectrum. In this work, we developed a formalism to describe the leakage due to instrumental widefield effects in visibility-based power spectra and used it to predict contaminations in observations. We find the leakage due to a population of point sources to be higher than the diffuse Galactic emission – for which we can predict minimal contaminations at k>0.3 h Mpc -¹ We also analyzed data from the last observing season of PAPER via all-sky imaging with a view to characterize the foregrounds. We generated an all-sky catalogue of 88 sources down to a flux density of 5 Jy. Moreover, we measured both polarized point source and the Galactic diffuse emission, and used these measurements to constrain our model of polarization leakage. We find the leakage due to a population of point sources to be 12% lower than the prediction from our polarized model.
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- Date Issued: 2019
Occurrence, feeding ecology, and population structure of two dolphin species, Tursiops aduncus and Delphinus delphis, off the Wild Coast of South Africa
- Authors: Caputo, Michelle Anne
- Date: 2019
- Subjects: Delphinus -- South Africa-- Kwazulu-Natal -- Ecology , Tursoops -- South Africa-- Kwazulu-Natal -- Ecology , Delphinus -- South Africa-- Kwazulu-Natal -- Feeding and feeds , Tursoops -- South Africa-- Kwazulu-Natal -- Feeding and feeds , Dolphins -- South Africa-- Kwazulu-Natal , Delphinus -- South Africa-- Kwazulu-Natal -- Behavior , Tursoops -- South Africa-- Kwazulu-Natal -- Behavior , Marine ecology -- South Africa -- Kwazulu-Natal
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115612 , vital:34197
- Description: Dolphins are apex predators and their movements, foraging activities and population dynamics play an important role in shaping their environment. Understanding their occurrence, movement patterns, and trophic ecology is essential to their conservation, especially as they are considered sentinel species. The Wild Coast of South Africa’s Eastern Cape, is characterized by the annual sardine (Sardinops sagax) run, which serves as an important foraging event for apex predators, including Indo-Pacific bottlenose (Tursiops aduncus) and long-beaked common dolphins (Delphinus delphis). Despite the ecological significance of this event, no dedicated surveys for these species have previously been conducted in this area. The main objectives of this research were to: investigate long-term occurrence of dolphins during the sardine run to determine if there have been any changes over the past 19 years, as has been predicted from common dolphin dietary investigations and anecdotal evidence; to determine short-term occurrence and movement patterns of selected inshore delphinids within the area, which is characterized by three marine protected areas (MPAs); and to use stable isotope analyses to determine trophic relationships and population structure of bottlenose and common dolphins within the region. Long-term data consisted of 131 opportunistic aerial surveys conducted between May and July over the period 1996 to 2014. Results from these surveys indicate that common dolphins, typically associated with sardines, decreased significantly in average group size over the study period (p=0.0343). Bottlenose dolphins, demonstrated no such trend (p=0.916). For both species, greater majority (> 70% of total counts) of sightings were made inside the MPAs. Short-term boat-based surveys were conducted three times a year between June 2014 and December 2016, contributing to a total of 47 days of surveys divided into three locations: Amathole, Hluleka, and Pondoland, each containing a MPA. Density and group size data were analyzed for both species and photographic identification analysis was performed for photographs of bottlenose dolphin dorsal fins. Results indicate that animal and sighting density did not differ temporally (bottlenose dolphin: sighting density – p=0.398, individual density –p=0.781; common dolphin: sighting density –p=0.472, individual density – p=0.204). Environmental factors (sea surface temperature, depth, substrate, and distance from shore) appeared to have limited effect on individual and sighting density and group size for both species (p>0.05). Photographic identification of bottlenose dolphins resulted in 2149 individuals, with a 11.8% resighting rate, with the highest resighting rate within the Pondoland MPA (16.1%). The resighting count did not differ temporally between monthly survey based on generalized linear models (p=0.866), but did differ between study areas (p<0.0001). These results provide the first evidence of the occurrence of both species of dolphin off the Wild Coast, as they were sighted in this region in all survey months. There was no trend in density based on temporal or environmental factors, which suggests other factors are influencing their occurrence. Resightings of bottlenose dolphins within the area suggest that there is some degree of residency, though the majority of animals were only sighted on a single occasion and there was no plateau in the discovery curve. A total of 256 biopsy samples (bottlenose dolphins =128; common dolphins=128) were collected during boat-based surveys. Bottlenose dolphin samples were also collected from adjacent areas to the southwest (Algoa Bay, n=22) and northeast (KwaZulu-Natal (KZN), n=20) of the Wild Coast to investigate similarities and differences between these areas. Despite a high degree of niche overlap between the two species (41%), common dolphins fed with a broader niche (standard ellipse area probability 0.89) than bottlenose dolphins in the summer and a narrower niche in the winter (probability 0.94). There was a clear spatial variation in the diet of bottlenose dolphins along the coast, with individuals from Algoa Bay and Amathole demonstrating 0% niche overlap with individuals from KZN, but the mechanism for these differences remains unclear as other species from South African waters demonstrate a strong southwest to northeast gradient in nitrogen for the Eastern Cape coastline. This research provides valuable baseline information regarding dolphins off the Wild Coast of South Africa, which remained largely unknown. My results indicate that bottlenose dolphins may be more resident in the Wild Coast than previous predicted, and confirm that common dolphins are highly mobile in this area.
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- Date Issued: 2019
Perspectives on land and water politics at Mushandike Irrigation Scheme, Masvingo, Zimbabwe
- Authors: Mafukidze, Jonathan
- Date: 2019
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/76479 , vital:30573
- Description: Access to, control and ownership of land and water, amongst other natural resources in Zimbabwe, shape and affect rural lives, livelihoods, social relations and social organisation. Rural poverty has been entrenched and exacerbated by, amongst other factors, highly restricted access to these scarce resources. Historically, Zimbabwe’s rural areas (such as communal areas, smallholder irrigation schemes and resettlement areas) have existed as sites of struggles where contestations and negotiations over access to, control or ownership of these resources have taken place. Resultantly, multifaceted and dynamic social relations have been weaved and contested social spaces carved out. In rural Zimbabwe, contestations have tended to be complex, nuanced and intricate, working themselves out in different ways across time and space. In their heightened and more visible state, they have been characterised by violent physical expressions which, in the history of the country, involved two wars of liberation, the First Chimurenga (1896-1897) and the Second Chimurenga (1960s to 1980). The most recent violent manifestation was through nation-wide land invasions, politically christened the Third Chimurenga, which peaked in 2000 and continued sporadically to this day. Few studies on smallholder irrigation schemes in Zimbabwe have focused on understanding how contestations for access to scarce land and water resources are framed and negotiated at the local level. Cognisant of this lacuna, this thesis uses social constructionism in examining, as a case study, Mushandike Smallholder Irrigation Scheme in Masvingo Province in order to understand and analyse how land and water politics occur at the local level. The study deploys a qualitative research methodology approach in examining local water and land politics, which involved original irrigation beneficiaries and more recent land invaders. Findings of the thesis indicate that land and water shortages have increased considerably in the past two decades at the irrigation scheme due to the influx of land invaders into the scheme. This influx has had a negative impact on agricultural production and other livelihood strategies. Both scheme members and land invaders lay claim to land and water at Mushandike. These claims are intricately constructed and contested, and they are linked to broader issues such as partisan party-politics, policy developments, and tradition, origin, indigeneity and belonging. Though the struggles over land and water at Mushandike are firmly rooted in the concrete conditions of existence and experiences of beneficiaries and land invaders, external actors such as political leaders, state bureaucrats and traditional chiefs tend to complicate and intensify the contestations.
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- Date Issued: 2019
Petrography and geochemistry of the Masoke Iron Formation and its associated ferruginous counterparts, kanye basin Botswana
- Authors: Nkabelane, Ndifelani Oriel
- Date: 2019
- Subjects: Petrology -- South Africa , Geochemistry -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115221 , vital:34101
- Description: A sequence of Transvaal Supergroup sediments extends into southern Botswana beneath Kalahari cover as the Kanye basin, these are known to host billions of tons @ 60>Fe. Masoke Iron Formation (Kanye Basin) which is stratigraphic correlative of The Ghaap Group and Chuniespoort Group of the Griqualand West basin and Transvaal basin, respectively. The Palaeoproterozoic Transvaal Supergroup in the Northern Cape Province of South Africa hosts high grade (>60% Fe) hematitic and specularitic iron and manganese mineralisation. It is therefore important to study and record the petrographic, mineralogy and geochemistry of Masoke Iron Formation, compare the results to the much known Kuruman and Griquatown Iron Formations. This study systematically investigate and record the petrography, mineralogy and geochemistry of all Masoke Iron Formation of Taupone Group in the Kanye Basin, which is stratigraphic correlative of The Ghaap Group and Chuniespoort Group of the Griqualand West basin and Transvaal basin, respectively. The further objective is to compare Masoke Iron Formation to the equivalent units in the Transvaal basin and Griqualand basin. In contrast to both Transvaal and Griqualand West Basin the Masoke iron Formation (Kanye Basin) has not been the subject of systematic scientific investigations. The study covers three main areas in the Kanye Basin: Keng Pan Area, Ukwi/Moretlwa hill and Janeng Hill Area. The mineralogy and geochemistry of these areas are presented in this study. Kanye Basin has a potential to host a large iron ore deposit, the geological setting in this area incorporates many of the elements necessary for iron ore formation. These include: banded iron formation (BIF), major unconformities with prolonged periods of weathering, carbonate sequences etc. In addition, several large deposits and mines are known from this area. This area can potentially have both hypogene and supergene enrichment of BIF. In this model, prospectively for new deposits is a function of the following: presence of iron formation units, proximity of mapped Asbestos Hills and Voëlwater BIF, thrust faulting (as indicated by the aero-magnetic interpretation), duplication of the ore horizon by folding, intersection of the BIF by major extensional fault, proximity of Olifantshoek/Waterberg outcrop, Gamagara unconformity, presence of carbonates (dolomites) and thin Kalahari sand cover. Major BIF units in the area of study include: the Masoke Iron Formation, equivalent to Kuruman Formation of the Asbestos Hills Subgroup, the Rooinekke iron formation of the Koegas Subgroup and the Hotazel Formation of the Voëlwater Subgroup. Supergene enrichment of these BIFs may occur wherever they are overlain by a major regional unconformity. The base of the Waterberg and the OlifantshoekSupergroups represent major unconformities in this regional target area. Potential for hypogene deposits is indicated by faulting (preferably extensional) proximal to BIF.
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- Date Issued: 2019
Ph-responsive liposomal systems for site-specific pulmonary delivery of anti-tubercular drugs
- Authors: Nkanga, Christian Isalomboto
- Date: 2019
- Subjects: Tuberculosis -- Chemotherapy , Lipsomes , Drug carriers (Pharmacy) , Rifampin , Hydrogen-ion concentration , Hydrogen-ion concentration -- Physiological effect
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/125832 , vital:35822
- Description: Tuberculosis (TB) is an infectious disease that has been reported to be the ninth leading cause of death worldwide, even though mostly considered as a poverty related disease. Despite the existence of potent anti-tubercular drugs (ATBDs), such as rifampicin (RIF) and isoniazid (INH), TB remains the major killer among many microbial diseases over the last five years. Although several factors are to be blamed for this deadly status, the most crucial issues encompass both the self-defensiveness of the causative agent (Mycobacterium tuberculosis), including its intra-macrophage location that compromises ATBDs accessibility, and the widespread/off target distribution of ATBDs. The need for novel drug delivery strategies therefore arises to provide selective distribution of ATBDs at the infected site. Among the drug vehicles explored in this field, liposomes have been reported to be the most suitable drug carriers due to their rapid uptake by alveolar macrophages, where M. tuberculosis often resides. Since liposomes experience media of different pH throughout the cell uptake process (endocytosis/phagocytosis), the use of pH change as a stimulus for controlled release looks promising for enhancing intra-macrophage delivery and minimizing premature ‘off-target’ release of ATBDs. However, the costly status of liposome technology, due to the use of sophisticated procedures and expensive materials (especially for pH-dependent delivery, where special lipids are required), may preclude wider developments of liposomal products, especially for the developing world. This study aimed at investigating liposomal encapsulation of pH-sensitive and fluorescent hydrazone derivatives of INH using crude soybean lecithin, as a cost-effective option for site-specific delivery combined with potential bio-imaging features. Another objective was to explore encapsulation of INH hydrazone derivatives with and without RIF in liposomes using a simple and organic solvent-free preparation method. Initially, INH was coupled with 4-hydroxy-benzaldehyde to yield a conjugate (INH-HB) that was encapsulated in liposomes using film hydration method with acceptable encapsulation efficiency (î), about 89 %. The prepared INH-HB loaded liposomes (IHL) were characterized by means of dynamic light scattering (DLS), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The release of INH from IHL was evaluated over 12 hours in media of different pH using dialysis. As hypothesized, pH dependent release of INH from IHL was observed with 22, 69, 83 and 100 % release obtained in media of pH 7.4, 6.4, 5.4 and 4.4, respectively. From this experimental trial, further development was undertaken by conjugating INH to a hydrophobic fluorescent tag, zinc (II) phthalocyanine (PC), through hydrazone linkages. The obtained conjugate (PC-INH) was loaded into liposomes (PIL) that were characterized using various spectroscopic techniques, including UV-Vis absorption and energy dispersive X-ray spectroscopy, which suggested the presence of PC-INH within the lipid bilayers. The release study performed in different pH media revealed 22, 41, 97 and 100 % of INH, respectively released at pH 7.4, 6.4, 5.4 and 4.4. This confirmed the potential of pH-triggered drug release from liposomes loaded with hydrazone drug derivatives. In addition, successful encapsulation of PC-INH using crude soybean lecithin inspired a new opening towards development of multimodal liposomes that could achieve controlled drug release with added benefits of image-guided biological tracking. However, the hydrophobic nature of PC-INH requires an effective strategy that could improve its solubility and favour extensive development. In this context, the tetra-substituted structure of PC-INH brought up the hypothesis that cyclodextrin (CD) complexation would facilitate PC-INH encapsulation in liposomes using an organic solvent-free method, called here the “heating method” (HM). Inclusion complexes of PC-INH with various CDs were therefore investigated, with gamma-CD complex (CP) giving the best results. These complexes were prepared in both solution and solid-state and further comprehensively characterized using UV-Vis spectroscopy, magnetic circular dichroism, NMR spectroscopy, diffusion ordered spectroscopy, DSC, XRD and Fourier transform infrared spectroscopy. CP-loaded liposomes prepared using HM exhibited greater î than film hydration liposomes, about 70 % versus 56 %, respectively. The HM-liposomal system (CPL) exhibited potentially useful nano particulate characteristics (i.e. mean particle size 240 nm and Zeta potential –57 mV), which remained unchanged over 5 weeks of stability study at 4 °C, and pH-dependent INH release behaviour alike PIL. Furthermore, CP was co-encapsulated with rifampicin (RIF) in liposomes using HM to investigate the possibility for future combination therapy. 1H-NMR spectroscopy, DSC, XRD and photophysical studies were performed for molecular assessment of the cargo in CP-RIF co-loaded liposomes (CPRL). The mean particle size, Zeta potential and î of CPRL were respectively 594 nm, –50 mV, 58 % for CP and 86 % for RIF. CPRL exhibited much higher release rates for both INH and RIF at pH 6.4, compared to those tested at pH 7.4. In addition, there was no cytotoxicity on HeLa cells, but attractive lung fibroblasts and epithelial cells uptake and viability. Hence, CPRL are promising for targeted ATBD delivery to alveolar macrophages following pulmonary administration. Overall, the developed pH-responsive liposomal system holds the promise for new openings towards wider developments of multifunctional liposomes for site-specific controlled pulmonary delivery of antimicrobials drugs.
- Full Text:
- Date Issued: 2019
Photocatalytic treatment of organic and inorganic water pollutants using zinc phthalocyanine-cobalt ferrite magnetic nanoparticle conjugates
- Authors: Mapukata, Sivuyisiwe
- Date: 2019
- Subjects: Phthalocyanines , Cobalt ferrite , Zinc , Nanoparticles
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67603 , vital:29119
- Description: This work explores the synthesis and photophysicochemical properties of zinc phthalocyanines when conjugated to cobalt ferrite magnetic nanoparticles. Phthalocyanines with amine and carboxylic acid functional groups were synthesised so as to covalently link them via amide bonds to cobalt ferrite magnetic nanoparticles with carboxylic acid and amine groups, respectively. Spectroscopic and microscopic studies confirmed the formation and purity of the phthalocyanine-cobalt ferrite magnetic nanoparticle conjugates which exhibited enhanced triplet and singlet quantum yields compared to the phthalocyanines alone. The studies showed that the presence of cobalt ferrite nanoparticles significantly lowered fluorescence quantum yields and lifetimes. The conjugates not only showed much higher singlet oxygen quantum yields compared to the phthalocyanines alone but were also attractive because of their magnetic regeneration and hence reusability properties, making them appealing for photocatalytic applications. The photocatalytic ability of some of the phthalocyanines and their conjugates were then tested based on their photooxidation and photoreduction abilities on Methyl Orange and hexavalent chromium, respectively. For catalyst support, some of the zinc phthalocyanines, cobalt ferrite magnetic nanoparticles and their respective conjugates were successfully incorporated into electrospun polystyrene and polyamide-6 fibers. Spectral characteristics of the functionalized electrospun fibers confirmed the incorporation of the photocatalysts and indicated that the phthalocyanines and their respective conjuagates remained intact with their integrity maintained within the polymeric fiber matrices. The photochemical properties of the complexes were equally maintained within the electrospun fibers hence they were applied in the photooxidation of azo dyes using Orange G and Methyl Orange as model organic compounds.
- Full Text:
- Date Issued: 2019
Photophysical properties and photodynamic therapy activities of symmetrical and asymmetrical porphyrins embedded into Pluronic polymer micelles and nonlinear optical properties of an asymmetrical phthalocyanine
- Authors: Managa, Muthumuni Elizabeth
- Date: 2019
- Subjects: Porphyrins , Phthalocyanines
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/67625 , vital:29122
- Description: This work reports on the synthesis of symmetrical and asymmetrical novel porphyrins that have been incorporated into Pluronic polymers, as well as the synthesis of asymmetrical phthalocyanine. The new compounds were characterized by elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR), mass spectrometry and UV–Visible spectroscopy. The porphyrins that are synthesised were not water soluble but upon incorporating into Pluronic polymer micelles, they became water soluble. The polymer was also modified and linked to folic acid, to enhance selectivity for photodynamic therapy application, where MCF7 breast cancer cells were used. The singlet oxygen quantum yields were lower for the metal free porphyrins as compared to metalled ones due to the heavy atom effect of ClGa, Zn and Cl2Si in the latter which encourages intersystem crossing to the triplet state. Singlet oxygen quantum yields for water soluble derivatives increased upon being encapsulated into the micelles for all. The Stern-Volmer constant (Ksv), binding constant (Kb) and number of binding sites (n) were investigated in order to understand the interaction between the polymer micelles and the porphyrins, and it was showed that the central metals play a role in the manner which the porphyrin interacts with the micelles. The dark toxicity and photodynamic activity of the novel porphyrins upon encapsulating to Pluronic polymer micelles is also reported. There was minimal dark toxicity for all complexes with > 90% cell survival. The photodynamic activity of water insoluble porphyrins improved when encapsulated into the micelles. Novel asymmetrical phthalocyanines were also synthesised for nonlinear optics (NLO) studies in solution and thin films.
- Full Text:
- Date Issued: 2019
Photophysicochemical properties and surface-enhanced Raman scattering of phthalocyanine-nanoparticle conjugates
- Authors: Nwahara, Nnamdi
- Date: 2019
- Subjects: Boron compounds , Electrochemistry , Phthalocyanines , Nanoparticles , Bioconjugates , Raman effect
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/71647 , vital:29928
- Description: This work presents the synthesis, photophysical and photochemical characterization of a series of metallophthalocyanines (MPcs) and boron dipyrromethene (BODIPY) and their conjugates with either gold or silver nanoparticles (AuNPs or AgNPs) or graphene quantum dots (GQDs). The rich π-electron systems of GQDs and MPcs employed in this work enabled the coordination of MPcs to GQDs (either as pristine or modified) via the non-covalent (π-π stacking) method. GQDs, AuNPs and AgNPs were also functionalized with L-glutathione (GSH) in order to assist coupling to the Pcs or BODIPY dye. Spectroscopic and microscopic studies confirmed the formation of the respective nanoparticles (NPs) as well as the conjugates which exhibited enhanced photophysicochemical properties in comparison to the phthalocyanines (Pcs) or BODIPY alone. This work also shows that the incorporation of folic acid (FA) into Pcs-NPs composites leads to further enhancements in the singlet oxygen generation capabilities of the resulting conjugates, and so experimentally demonstrates for the first time, a synergy between FA and the respective nanoparticles (GQDs, AuNPs and AgNPs) in affecting the photophysical properties of Pcs complexes. GQDs and Pcs/GQDs hybrids were also herein decorated with AuNPs – metallic nanostructures that employ localized surface plasmon resonances to capture or radiate electromagnetic waves at optical frequencies. These nanostructures herein reported, have been shown to possess enhanced light-matter properties, enabling unique surface-enhanced Raman scattering (SERS) behaviours, with unprecedented enhancement factors of up to 30-fold. This work therefore, reports on the fabrication of Pc/GQDs/AuNPs hybrids and experimentally demonstrates their incredible potential as novel Raman-active PDT agents.
- Full Text:
- Date Issued: 2019
Physicochemical properties and photodynamic therapy activities of indium and zinc phthalocyanine-nanoparticle conjugates
- Authors: Dube, Edith
- Date: 2019
- Subjects: Indium , Zinc , Phthalocyanines , Breast -- Cancer -- Photochemotherapy , Nanoparticles
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/76506 , vital:30589
- Description: The syntheses and characterization of symmetric and asymmetric Pcs functionalized at the peripheral position are reported. The Pcs contain either zinc or indium as central metals and have carboxyphenoxy, phenoxy propanoic acid, benzothiazole phenoxy, thiophine ethoxy or di-O-isopropylidene-α-D-glucopyranose as ring substituents. The Pcs were linked to NPs via an amide bond or through self-assembly. The photophysics and photochemistry of the Pcs were assessed when alone and with conjugates. All the studied Pcs showed good photophysicochemical behaviour with relatively high triplet and singlet oxygen quantum yields corresponding to their low fluorescence quantum yield. The Pcs with indium in their central cavity exhibited higher triplet and singlet oxygen quantum yields in comparison to their zinc counterparts due to the heavy–atom effect obtained from the former. Asymmetrical Pcs displayed higher triplet and singlet oxygen quantum yields than their symmetrical counterparts. The triplet quantum yield, generally increased on linkage to nanoparticles (NPs) due to the heavy–atom effect of gold and silver in NPs. The conjugates to gold nanospheres yielded higher triplet and singlet quantum yields than their gold nanotriangles counterparts due to the higher loading by the former probably encouraged by their relatively small particle size. The in vitro dark cytotoxicity and photodynamic therapy of selected Pc complexes and conjugates against MCF-7 cells was tested. All studied Pc complexes and conjugates showed minimum dark toxicity making them applicable for PDT. All complexes displayed poor phototoxicity with >50Îll viability at concentrations≤ 160μg/mL, however the conjugates showed<50% cell viabilityatconcentrations≤ 160μg/mLprobably due to the enhanced singlet oxygen quantum yield. The findings from this work show the importance of linking photosensitises such as phthalocyanines to metal nanoparticles for the enhancement ofsinglet oxygen quantum yield and ultimately the photodynamic effect.
- Full Text:
- Date Issued: 2019
Plants, people, and place: complex, mutualistic, and co-evolving global patterns through time
- Authors: Van Wijk, Yvette Ethné
- Date: 2019
- Subjects: Ethnobotany -- South Africa -- Western Cape , Khoisan (African people) -- Ethnobotany , Human-plant relationships -- South Africa -- Western Cape , Plants -- Classification -- South Africa -- Western Cape , Plant remains (Archaeology) -- South Africa -- Western Cape , Ethnoscience -- South Africa -- Western Cape , Regression analysis
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/76575 , vital:30609
- Description: My thesis studies and analyses the suite of distinctive plant taxa which persist in small patches of vegetation growing in close association with archaeological habitation sites in the southern Cape, South Africa. The unexpected correlation and overlap between botanical taxa collected at 75 site complexes, and ethnobotanical data collected in collaboration with modern Khoi-San communities in the same area, is explored and interrogated. Although sparse, reports of the same suite of taxa recovered from archaeological excavations in the Cape provinces provides depth of time to the study, linking the past to the present. The three-way correlation of a suite of plants closely associated with humans and habitation sites through time, allows for triangulation of the data in order to validate and cross verify the results using more than one frame of reference. Both the plants and the knowledge about their uses have persisted in spite of historical attrition, and alienation of land and language, suffered by the Khoi-San over the past 300 years. Drawing on a large body of primary and secondary data, and using an interdisciplinary, abductive and pragmatic mixed methods approach, a pattern can be traced throughout Africa and globally. Regression analysis strongly indicates that the most ubiquitous taxa were selected for a purpose and are not randomly present in association with humans. Botanical, anthropological, and archaeological studies seldom focus on the inter-connectedness of people and plants at the sites they inhabited. Very little research into modern vegetation in close association with the sites has been undertaken, and vegetation mapping has not captured the occurrence of these site-specific small vegetation patches recorded during my surveys. The topographically, geologically, and vegetatively complex and varied southern Cape, and greater Cape area, is extremely rich in archaeological sites and history. This study suggests that the value of site-specific plant taxa to humans throughout the aeons of pre-agricultural history, persists into the present. Due to tolerance of a broad range of climatic and environmental variables, there is value in the study of these ancient and neglected useful plants in the face of climate change. That this vegetation is so closely associated with archaeological sites of cultural and historic importance confers an urgency to recognising the existence and significance of the distinctive and possibly anthropogenic vegetation surrounding the sites.
- Full Text:
- Date Issued: 2019
Popular politics in the rural Western Cape, South Africa: a case study of Ruiterbos
- Authors: Ghedi Alasow, Jonis
- Date: 2019
- Subjects: Political participation -- South Africa -- Cape Town , South Africa -- Politics and government -- 1994- , Land tenure -- Political aspects -- South Africa , Land use, Rural -- Political aspects -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/96165 , vital:31246
- Description: This thesis argues that the philosophical foundations upon which human beings have been engaged have, across various schools of thought, made the mistake of presuming that some people are more modern than others. This suggestion is refuted throughout this thesis. To do this, intellectual traditions that take the fundamental rationality of all human beings as an indispensable starting point are engaged to argue for the need to acknowledge that everyone in the ‘now’ is indeed, of the ‘now’. This thesis connects these debates about modernity, rationality and humanity to the contemporary discussions around rural politics with particular reference to Ruiterbos in the Western Cape province of South Africa. By means of detailed empirical and ethnographic research, this thesis illustrates the issues around which people in Ruiterbos are politicised. Via this case study, the a priori assumption that rural politics will necessarily manifest itself only with respect to questions of land and agrarian reform or labour relations is complicated. The two issues around which people in Ruiterbos, during the time of this research, seem to be politicised – housing and education – are surfaced throughout this thesis. The thesis argues that the findings in this case study call for an expansion of the issues that are traditionally considered when the question of rural politics is raised. The often historicist approach that limits the possibilities for politics in rural areas should be suspended for an approach that takes popular politics and political agents in rural areas seriously. The thesis finally argues that the conclusions that are reached with respect to questions of modernity and rural politics ought to be adopted to allow for more detailed and thorough explanations of popular politics in places like Ruiterbos.
- Full Text:
- Date Issued: 2019
Post-release evaluation of Megamelus scutellaris Berg. (hemiptera: delphacidae): a biological control agent of water hyacinth Eichhornia crassipes (Mart.) Solms-Laub (Pontederiaceae) in South Africa
- Authors: Miller, Benjamin Erich
- Date: 2019
- Subjects: Megamelus scutellaris Berg. , Delphacidae , Noxious weeds -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Water hyacinth -- Biological control -- South Africa , Biological pest control agents
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92330 , vital:30710
- Description: Water hyacinth, Eichhornia crassipes (Mart.) Solms-Laub. (Pontederiaceae) is a free-floating aquatic macrophyte from South America that was introduced to South Africa in the 1900s for its attractive ornamental flowers. The plant was classified as a serious invader in the country in the 1970s, eventually becoming the worst invasive aquatic plant in South Africa. Biological control is widely regarded as the most effective method of managing water hyacinth, as it is ecologically safe, cost-effective, and self-sustaining. To date, nine biological control agents have been released in South Africa against water hyacinth, including eight arthropods and a pathogen. Due to the cumulative effects of highly eutrophic waterbodies, which mitigate the damage caused by biological control, and the cold winters which inhibit the rate of biological control agent population build up, South Africa currently has more biological control agents released on water hyacinth than anywhere else in the world. The need for a cold-tolerant agent that can reproduce and develop quickly, while still being damaging to water hyacinth in eutrophic systems, led to the introduction of the most recently released water hyacinth biological control agent, the planthopper Megamelus scutellaris Berg (Hemiptera: Delphacidae), which was initially collected from Argentina. This thesis formed the first post-release evaluation of M. scutellaris since its release in South Africa in 2013. It included a greenhouse experiment to measure the agent’s feeding damage in relation to different nutrient levels and stocking rates, as well as a field component to evaluate both the post-winter recovery of M. scutellaris, and a nationwide survey to measure the establishment of the agent around the country in relation to climate, water quality, and plant health. In the greenhouse experiment, the feeding damage was quantified using measurements of plant growth parameters and chlorophyll fluorometry. It was found that, like other biological control agents of water hyacinth, M. scutellaris was most damaging when released in high numbers on plants grown at medium nutrient levels, and less effective on plants grown at elevated nutrient levels. A water hyacinth infestation on the Kubusi River was selected for the evaluation of the post-winter recovery of M. scutellaris. The Kubusi River is both the first site where M. scutellaris was released, and the coldest site where water hyacinth biological control agents have established successfully in South Africa. Monthly visits tracking seasonal plant health characteristics and agent population densities indicated that the populations of M. scutellaris were impacted most significantly by the season. Low temperatures led to the water hyacinth plants being of poor quality during the winter, which had a subsequent negative effect on the agent populations. The agents could only fully recover by late summer, which meant that the plants were without any significant biological control through the initial phases of the growing season, when they were most vulnerable, and a significant lag-phase occurred between the recovery of the plants and the recovery of the agent population after the winter bottleneck. A survey of all sites where M. scutellaris had been released in South Africa yielded 16 sites where the agents had successfully established, having survived at least one full winter. Among these sites were four sites where the agents were found without them having been released, indicating that they can disperse unaided to new sites. The temperature was a major factor responsible for the success or failure of establishment, with very few agents surviving in the hot areas of South Africa or in areas with a high frost incidence. The density of M. scutellaris was higher in nutrient-rich water, and on plants with more leaves, suggesting that the quality of the plants also contributed to establishment. The results of this thesis showed that M. scutellaris is able to establish successfully in South Africa, and that the agents are capable of causing significant damage to water hyacinth, making it a promising addition to the biological control programme. Novel methods of measuring subtle insect feeding damage in plants and quantifying agent populations are also discussed, along with suggestions for the future implementation of M. scutellaris in South Africa.
- Full Text:
- Date Issued: 2019
Psychotherapy in post-colonial SA: exploring attitudes, views and beliefs of rural ‘black’ communities on psychotherapy
- Authors: Mthembu, Thembekile Thobeka
- Date: 2019
- Subjects: Black people -- Attitudes -- South Africa , Black people -- Psychology -- South Africa , Black people -- Mental health -- South Africa , Psychotherapy -- South Africa , Client-centered psychotherapy -- South Africa , Rural families -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/71419 , vital:29847
- Description: The appropriateness and effectiveness of the field of psychology and its branch psychotherapy has been met with fierce criticisms especially in contexts outside of Western or Euro American or urban Southern Africa. This thesis explores attitudes, views and beliefs of rural ‘black’ communities on psychotherapy (the healing process of the mind and soul). It is important to understand how the healing process of the mind and soul is constructed and practised in South African black rural communities, and this remains an imperative of psychology. The study takes an exploratory qualitative research approach. Nine participants from two rural communities in Kwa-Zulu Natal were interviewed through face-to-face semi-structured interviews. Thematic analysis was utilised as a method of data analysis. The study employed social constructionism and Afrocentricity as theoretical points of departure. The findings were understood through employing Afrocentricity theory underpinned by post-colonial theory. Four main themes were derived with supporting subthemes. The themes indicate that rural black communities’ attitudes, views, and beliefs on psychotherapy are at variance with the Western perspective of psychotherapy. This is further associated with the practise of psychotherapy in rural black communities. The findings of this study can possibly assist in new understandings of psychotherapy as constructed in different contexts and instigate future research to be conducted in often-neglected areas such as rural communities.
- Full Text:
- Date Issued: 2019