The solvent-free approach versus the use of ionic liquids in the synthesis of ferrocenes
- Authors: Elago, Elago R T
- Date: 2008
- Subjects: Ferrocene , Inorganic compounds -- Synthesis , Ionic solutions , Solvents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10396 , http://hdl.handle.net/10948/853 , Ferrocene , Inorganic compounds -- Synthesis , Ionic solutions , Solvents
- Description: The philosophy of green chemistry has seen much development in the past decade. The use of environmentally benign solvents is amongst the areas of green chemistry that have received the most attention. In this context, imidazolium ionic liquids have been widely reported to offer high product yields, fast reaction rates, excellent selectivity and generally mild working conditions, when used as reaction media. In addition, concerns about costs of solvents and the long-term environmental impact that can potentially result when solvents are discarded after their use have led to focused investigations into solvent-free procedures, as reported in recent literature. We have set out to explore the extent to which these advantages could be realized within our research. Non-volatile, non-flammable imidazolium ionic liquids [bmim][I], [bmim][BF4] and [bmim][PF6] were used as green solvents in ferrocene chemistry. Ferrocenoate esters were synthesised efficiently by the respective DCC/DMAP-promoted reactions of ferrocenecarboxylic acid and substituted benzoic acids or, alternatively, the DMAP-promoted reactions of ferrocenoyl fluoride with a range of substituted phenols in [bmim][BF4] and [bmim][PF6]. High yields and short reaction times were achieved. In addition, the ionic liquid was reused several times without a reduction in product yields. Under solvent-free conditions, DCC/DMAP-promoted reactions provided high yields within 3 min of reaction. The possible rearrangement of one of the intermediates in these reactions was modelled theoretically using density function theory (DFT) at the B3LYP/6-31G* level of approximation. Catalyst-free esterification was achieved by the application of microwave radiation to the reaction of ferrocenoyl fluoride and a range of substituted phenols. All the reactions were complete after 1 min of irradiation and products were isolated in high yield. DPAT, HfCl4, Sc(OTf)3 and Al(OTf)3 were screened as catalysts for esterification in [bmim][BF4] and under solvent-free conditions at various temperatures. All attempts at esterification of ferrocenecarboxylic acid with alcohols and phenols were unsuccessful. The Suzuki cross-coupling reaction was carried out in [bmim][BF4]. The isolated yields are, however, poor and suffer from poor reproducibility with different batches of [bmim][BF4] used.
- Full Text:
- Date Issued: 2008
The sociology of police criminality and ill-discipline in Buffalo City Metropolitan Municipality, South Africa
- Authors: Long, Amy Megan
- Date: 2019
- Subjects: Police -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/17462 , vital:41078
- Description: Policing as a global concept, involves an exchange of trust between the public and a given police service, with the underlying basis of this exchange being an understanding that the police exist to protect citizens and their property, and to ensure that order is maintained in societies. The police services, by virtue of the nature of their role in society, can therefore be regarded as ‘protectors’. The South African Police Service are guided by the same philosophies as policing services globally. Recently in South Africa though, there has been an increase in reports accusing policemen of becoming involved in criminal activities themselves. With a focus on the Buffalo City Metropolitan Municipality policing district, this study presents and analyses incidences of undocumented police crimes; the causes thereof; and the role of disciplinary procedures (both internally and legally) in preventing such incidences of crime. This study utilised a qualitative methodology to gather and analyse data. A total of 60 serving police officers and 10 key informants were selected using purposive and snowball sampling. In-depth semi-structured interviews conducted with these police officers and key informants, reveal that police men and women are involved in violent and economic crimes in the Buffalo City Metropolitan Municipality policing district. Most violent crimes include assault, and torture; whilst economic crimes include corruption and theft. Underlying reasons for such crimes include inadequate remuneration, frustration in respect of the efficacy of the criminal justice system, vigilantism within the policing services, and socially learned violence. Internal (within SAPS and IPID) and legal disciplinary measures (through the criminal and civil justice system) were established to be ineffective in managing and eradicating incidences of both violent and economic crimes. The consequences of incidences of police criminality are reduced legitimacy of the policing services to deliver on its mandate to protect and serve the people of the Republic of South Africa.
- Full Text:
- Date Issued: 2019
The SKA's the limit : on the nature of faint radio sources
- Authors: McAlpine, Kim
- Date: 2013 , 2012-09-14
- Subjects: Radio telescopes -- South Africa Radio astronomy -- South Africa Square Kilometer Array (Spacecraft)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5504 , http://hdl.handle.net/10962/d1007271
- Description: From abstract: Within the next few years a large number of new and vastly more sensitive radio astronomy facilities are scheduled to come online. These new facilities will map large areas of the sky to unprecedented depths and transform radio astronomy into the leading technique for investigating the complex processes which govern the formation and evolution of galaxies. This thesis combines multi-wavelength techniques, highly relevant to future deep radio surveys, to study the evolution and properties of faint radio sources. , TeX , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
The significance of the local trade in natural resource products for livelihoods and poverty alleviation in South Africa
- Authors: Shackleton, Sheona E
- Date: 2006
- Subjects: Poverty -- South Africa Rural poor -- South Africa Natural resources -- South Africa Selling -- Handicraft South Africa -- Commerce
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4776 , http://hdl.handle.net/10962/d1011731
- Description: What role can the commercialisation of natural resource products play in the efforts to reduce poverty and vulnerability and how can this be enhanced? With poverty alleviation at the top of the global development agenda, this is a question posed by many scholars, practitioners, donor agencies and government departments operating at the environment-development interface. However, recent commentary on this issue is mixed and ambiguous, with some observers being quite optimistic regarding the potential of these products, while others hold a counter view. This thesis explores the livelihood contributions and poverty alleviation potential of four products traded locally in the Bushbuckridge municipality, South Africa; namely traditional brooms, reed mats, woodcraft and a beer made from the fruits of Sclerocarya birrea. A common approach, employing both quantitative and qualitative methods, was used to investigate the harvesting, processing and marketing arrangements, sustainability and livelihood contributions of each product. The results illustrate that any inference regarding the potential of the trade to alleviate poverty depends on how poverty is defined and interpreted, and on whether the role of these products is assessed from a holistic livelihood perspective that includes notions of vulnerability, alternatives and choice, diversification and the needs of rural producers themselves. Overall, the products studied were key in enhancing the livelihood security of the poorest members of society, forming an important safety net and assisting in raising household incomes to levels equivalent to the wider population, but generally were unlikely, on their own, to provide a route out of poverty. However, there were notable exceptions, with marked variation evident both within and across products. Incomes often surpassed local wage rates, and a minority of producers were obtaining returns equivalent to or greater than the official minimum wage. Other benefits, such as the opportunity to work from home or to diversify the livelihood portfolio, were also crucial, with the trade representing different livelihood strategies for different households. When viewed within the context of rising unemployment and HIV/AIDS these findings assume greater significance. While the trades were complex and growth limited, livelihood benefits could be improved on a sustainable basis if the sector was given the attention and support it deserves.
- Full Text:
- Date Issued: 2006
The shuttle effect : the development of a model for the prediction of variability in cognitive test performance across the adult life span
- Authors: Jordan, Ann B
- Date: 1998
- Subjects: Cognition -- Age factors Aging -- Psychological aspects Cognition in old age Human information processing -- Age factors Older people -- Psychology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3191 , http://hdl.handle.net/10962/d1008556
- Description: The aim of this thesis was to investigate inter-individual variability on cognitive task performance in normal older adults. In a review of the cognitive aging literature, the implications of a differential perspective were drawn out in order to establish a theoretical and methodological basis for an investigation into variability. A number of regularly occurring patterns, identified on the basis of available reports in the literature, were used to develop a model of variability (the shuttle model). The empirically-based model was located broadly within a neuropsychological framework, and derived explanatory power from the tenets of brain reserve capacity (BRC) theory. It served to describe the bulge in interindividual variability due to aging (the shuttle bulge), and the shifting occurrence of the bulge in relation to the age axis due to cohort and task-related influences (the shuttle shift). A two phase research study was conducted in order to test hypotheses derived from the model. Phase 1 comprised between-groups analyses of normative data covering a broad range of neuropsychological tests in the domains of attention, memory, language, visual and hand motor skills, in order to examine the progression of variability effects across the adult age range. Phase 2 constituted between and within-groups analyses of normative data from a more limited number of neuropsychological tests. It included the examination of raw score distributions and the characteristics of outliers, and was undertaken to explore more closely the nature of the variability phenomena detected in the first phase of the analysis. Taken together, the results of both phases of the investigation revealed statistically significant variability effects in support of the shuttle model. There was a consistent pattern of increased variability in association with older age regardless of functional modality; frequently, in association with later old age, there was also a subsequent decrease in variability (the shuttle bulge). The age of onset of the initial increase in variability occurred earlier or later (the shuttle shift) as a function of four factors: education, gender, task challenge and age-sensitivity of task. The finding of an earlier onset of variability effects for low education, male gender, high task challenge and high age-sensitivity of task was interpreted in terms of BRC threshold theory. The clinical and social implications of the outcome were discussed with special emphasis on the need for a differential perspective on aging, as a complement to the prevailing normative tradition. It was concluded that the shuttle model has considerable heuristic value. It presents an integrative framework for understanding existing variability data and provides clear indications for future research.
- Full Text:
- Date Issued: 1998
The separation of platinum and gold from an industrial feed solution
- Authors: Louw, Talana
- Date: 2008
- Subjects: Platinum -- Separation , Gold , Separation -- Technology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10400 , http://hdl.handle.net/10948/731 , Platinum -- Separation , Gold , Separation -- Technology
- Description: In this thesis, the aim was to develop resins which are platinum and gold specific to be utilized for the early removal of these metals from the industrial feed. Efforts were therefore directed towards the synthesis of silica based resins with active centra which were designed for platinum and gold specificity respectively. The large chlorometallate ions in the feed stream were characterized in terms of physical parameters relevant to phase distribution namely distortability (RD), charge density, softness (σ) etc. Matching cations for each of the types were investigated. In order to attempt the design of platinum specific resins different structural amines were used to aminate the silicone precursor and subsequently to fix these onto the silica framework. Two different solvents i.e. alcohol and dmf were used for this process, resulting in two sets of resins with different properties. For gold specific resins, various polyethers were attached to a different type of silicone precursor, which was attached to the silica framework. The design was based on previous experience with these ions with reference to their behaviour towards different types of cations. The platinum species PtCl6 2- and PtCl4 2-, the gold species AuCl4 -, as well as the most important contaminants in the feed stream were typified bearing in mind size, charge, charge density and distortability. Different types of cationic centra having differences in charge density, stereochemical crowding and extent of hydrophobicity were synthesized and tested both as solvent extractants (where possible) and silica based resins. The results indicated that partly screened secondary ammonium cationic resin species, which could be regarded as “intermediate”, proved to be satisfactory both in their high percentage extraction for PtCl4 2- and rejection of contaminants like chlororhodates, chloroiridates(III) and FeCl4 -. It was, however, necessary to work at a redox potential where iridium(IV) in the form of IrCl6 2- is absent. Various 2-aminoalkane resins were prepared with variation in the length of alkane group and synthesized in the two different solvents. The latter resulted in two sets of resins with different compactness also having significantly different properties with reference to platinum specificity, HCl effect and stripping potential. The 2- aminobutane and 2-aminoheptane resins both proved to be very satisfactory platinum specific resins with respect to selectivity, platinum capacity and stripping potential. The various physical parameters could be utilized to accommodate the chemical behaviour. To obtain gold specific resins, experiments were performed with resins having oxygen-donor atoms which can readily be protonated to form onium type cations for example amides and ether oxygen atoms. In the case of the latter, various polyethers with a different number of ether groups (polyether groups linked by ethylene and propylene groups) and variations of hydrophobicity (by substitution) have also been studied. Linked to the polyether groups were alkane and aryl groups. Those having 8 to 10 ether groups and aromatic tail ends proved to be moderately successful in terms of gold capacity and sharp breakthrough curves of their columns, however, platinum could not be very effectively rejected.
- Full Text:
- Date Issued: 2008
The sedimentology of the Zerrissene turbidite system, Damara Orogen, Namibia
- Authors: Swart, Roger
- Date: 1991
- Subjects: Sedimentology Sediments (Geology) -- Namibia Sedimentation and deposition Turbidites
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5000 , http://hdl.handle.net/10962/d1005613
- Description: The Zerrissene turbidite system of central-western Namibia is a late Proterozoic sequence which consists of dominantly siliciclastic turbidites interbedded with minor turbiditic and hemipelagic marbles. The basin in which these sediments were deposited is located at the junction of the coastal and intra-cratonic arms of the Pan-African Damara Orogen, and an understanding of the sedimentary evolution of this basin is therefore important to the understanding of the development of the orogen as a whole. One major and two minor phases of folding have deformed the sediments, but the grade of metamorphism is low and sedimentary structures are often well preserved. Further, the area lies entirely within the Namib Desert and the lack of vegetation cover results in good outcrops providing an unusual opportunity for examining a large Precambrian turbidite system. The system consists of five formations: three siliciclastic and two mixed carbonatesiliciclastic units. The floor of the system is not exposed, and the oldest sedimentary rocks which outcrop are siliciclastics of the Zebrapiits Formation. This is overlain successively by the Brandberg West Formation (dominantly calcareous), the Brak River Formation (siliciclastic), the Gemsbok River Formation (calcareous) and the Amis River Formation (siliciclastic). Nine silicilastic turbidite facies have been recognised in the basin. These are facies A₂ (disorganised onglomerates), B₁ (horizontally laminated to massive greyackes), C₂ ("classical" turbidites), Dl (sandstone-shale couplets with base cut-out Bouma sequences), D₂ (sandstone-shale couplets with less sand than shale and base cut-out Bouma sequences), E (coarse, discontinuous sandstone-shale couplets), F (slumped units), G (shale) and H (glacial dropstones). Four facies are associated with the carbonate horizons, and these carbonate facies are given the suffix c to distinguish them from similar siliciclastic facies. These are facies Ac (disorganised and graded marble breccias), facies Cc (graded carbonates), facies Gc (hemi-pelagic marbles) and facies G (pelagic shales). The basal Zebrapiits Formation is made up of relatively thin packages of thin- to thickbedded, laterally continuous facies D₁, D₂ and B₁ beds encased in thick envelopes of shale. This type of sequence is typical of a distal lobe-fringe, and requires an unconfined basin-floor on which it can develop. The overlying Brandberg West Formation consists of a basal portion of interbedded facies Cc and G, followed by a sequence dominanted by facies Gc. This sequence is interpreted as representing outer-apron carbonate turbidites, derived from multiple point sources (facies Cc), with background pelagic settling (facies G) overlain by hemi-pelagic deposits (facies Gc). A reversal back to siliciclastic turbidites followed with deposition of the Brak River Formation. This sequence comprises relatively thick packages of laterally continuous facies B₁, D₁, and D₂ beds sandwiched between facies G shales, a succession characteristic of a lobe to lobe-fringe environment with intermittent abandonment of lobes. An unconfined basin floor adjacent to a passive margin is required for the development of this type of sequence. Glacial dropstones (facies H) are found in the upper portions of this formation, and slumped beds are also present (facies F), but are uncommon. The facies F beds are only found in association with facies H and are therefore considered to be genetically related. Slumping of beds was possibly caused by an oversupply of sediment from ice-rafting which caused instability. The overlying Gemsbok River Formation has a sequence similar to the Brandberg West Formation in that the basal portion consists of interbedded facies Cc and G, which is overlain by a thick sequence of largely facies Gc beds. Minor facies Ac beds occur near the top of the overall sequence. This formation is interpreted as an outer-apron succession with the facies Ac beds representing distal inner-apron deposits, indicating progradation of the system. The youngest unit in the basin, the Amis River Formation, shows strong lateral variation from west to east. In the west the sequence comprises laterally continuous facies B₁, C₂, D₁ and D₂ with rare, discontinuous facies E beds. Facies G is relatively minor in the sequence. In the east the succession is dominated by facies D₁, D₂ and G, and this succession is interpreted as a sequence of distal turbidites which were deposited on a basin-plain. The system developed by aggradation rather than progradation as only minor cycles are developed. Geochemical and petrological features indicate that the entire siliciclastic system was derived from a granite-recycled orogen terrane. Palaeocurrent data are unreliable because of the deformation, but transport was initially from the south-west, moving later to the west and north-west. The provenance of the carbonates is uncertain as reliable palaeocurrent indicators are rare, but they could have been derived either from South America or from the extensive carbonate deposits developed on the north-western margins of the basin. The Zenissene siliciclastic turbidite system represents the distal portion of a major submarine turbidite system, the more proximal parts of which now lie west of the exposed basin, either under the Atlantic Ocean or in eastern South America. The calcareous deposits developed as an apron adjacent to a multiple point source, the position of which is at present unknown.
- Full Text:
- Date Issued: 1991
The screening and characterisation of compounds for modulators of heat shock protein (Hsp90) in a breast cancer cell model
- Authors: Moyo, Buhle
- Date: 2013 , 2013-07-18
- Subjects: Heat shock proteins Breast -- Cancer Breast -- Cancer -- Chemotherapy Breast -- Cancer -- Treatment Cancer cells Naphthoquinone PQQ (Biochemistry)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4060 , http://hdl.handle.net/10962/d1004129
- Description: Breast cancer is a leading cause of cancer death in Africa. Hsp90 has been identified as a target for anti-cancer treatments as its inhibition results in the disruption and ubiquitin–proteasome degradation of activated oncoproteins. Currently, there are no US Food and Drug Administration approved Hsp90 inhibitor drugs and existing Hsp90 inhibitors such as geldanamycin and novobiocin are hepatotoxic and display a low affinity for Hsp90, respectively. Therefore, there is a need for the development of Hsp90 inhibitors with improved inhibitory properties. In this study twelve natural compounds bearing a quinone nucleus were screened and characterised for the modulation of Hsp90. The compounds analysed formed three series; the sargaquinoic acid (SQA), naphthoquinone, and pyrroloiminoquinone alkaloid series. Certain compounds exhibited half maximal inhibitory concentrations of between 3.32 μM and 12.4 μM, while others showed no antiproliferative activity at concentrations of up to 500 μM in the MDA-MB-231 breast adenocarcinoma cell line. Immunofluorescence and Western analyses indicated that the modulation of Hsp90 and partner proteins by SQA was more similar to that of novobiocin. Isothermal titration calorimetry analyses suggested that SQA interacted with Hsp90β with a low affinity, and saturation-transfer difference nuclear magnetic resonance confirmed that this interaction with Hsp90β occurred through the methyl moiety bound to 1, 4 benzoquinone of SQA. Pulldown assays indicated SQA disrupted the association between Hsp90 and Hop dose-dependently, more similarly to novobiocin. Immunofluorescence and Western analyses performed on naphthoquinone and pyrroloiminoquinone alkaloid compounds indicated modulation of Hsp90 and Hsp90 partner proteins by the compounds. Naphthoquinone compounds were prioritised for analysis for binding to Hsp90β over the pyrroloiminoquinone alkaloid compounds. Lapachol interacted with Hsp90β with a low affinity however; this interaction was thought to be too weak to disrupt the association of Hsp90 and Hop. The remaining naphthoquinone compounds showed no interaction with Hsp90β, thus allowing the determination of a preliminary structure-activity relationship for these compounds. To the best of our knowledge, this is the first study to describe a systematic subcellular analysis of the effects of geldanamycin and novobiocin in comparison to sargaquinoic acid and compounds of the naphthoquinone and pyrroloquinoline scaffold on Hsp90 and its partner proteins. , Microsoft� Word 2010 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
The rupture in the Rainbow: an exploration of Joburg Pride’s fragmentation, 1990 to 2013
- Authors: McLean, Nyx Nicolene Cindy
- Date: 2018
- Subjects: Gay pride celebrations -- South Africa -- Johannesburg , Sexual minorities -- South Africa , Sexual minorities -- Crimes against -- South Africa , Hate crimes -- South Africa , Group identity -- South Africa -- Johannesburg , Identity politics -- South Africa -- Johannesburg , Racism -- South Africa , One in Nine Campaign
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63822 , vital:28492
- Description: In 2012 Joburg Pride was disrupted by the One in Nine Campaign who asked for a moment of silence to honour the lives of victims of hate crimes1 and violence. This interruption of the parade was met with violence from Joburg Pride organisers, marshals and participants, who explicitly told the campaign’s activists that they “had no right to be at the parade.” The activists were predominantly black lesbians and gender non-conforming people. This response suggested that there was no place within Joburg Pride for honouring and mourning the lives of LGBTIAQ people of colour that had been lost to hate crimes. In addition to the call for one minute of silence, the One in Nine Campaign argued that Joburg Pride had become depoliticised as a result of its increased commercialisation. This study is motivated by a need to understand this rupture that occurred in 2012, and to situate it within the history of the LGBTIAQ movement in South Africa. In particular, it investigates the argument made by the One in Nine Campaign that Joburg Pride had become depoliticised and commercialised. The tensions that were facilitated by the 2012 clash and the subsequent formation of alternative Pride events in 2013 are interesting in light of current conversations circulating in broader South African discourse around what it means to be a South African citizen. The study applies a poststructuralist, anti-racist queer feminist lens informed by queer theory, critical theory, critical race theory, and whiteness studies to the historical and current fractures within Joburg Pride. The study analyses Exit newspaper articles from 1990 to 2013, alongside interviews with key stakeholders involved in the 2012 clash. The analysis, informed by both thematic and discursive approaches, interrogates the following themes: depoliticisation, commercialisation, “community”, assimilation, whiteness, racism, rainbowism and rainbow-washing. In this thesis I argue that the commercial interests and apolitical stance of predominantly white Joburg Pride organisers came to exclude LGBTIAQ people of colour’s experiences, at a time when political organising around hate crimes was most necessary. The analysis further highlights a politics of assimilation rooted in rights-based discourse informed by the Rainbow Nation rhetoric of post-apartheid South Africa. Further, this study problematises the notion of “community”, and discusses its strategic use in assimilationist politics within the LGBTIAQ “community”. This study shows that the rupture in the rainbow that occurred at Joburg Pride 2012 was constituted by multiple ruptures that exist in South African society. The issues explored in this thesis are therefore not only useful for constructing more inclusive spaces for LGBTIAQ people, but also for the nation building project of South Africa.
- Full Text:
- Date Issued: 2018
The role of upwelling in determining the composition, species distribution and genetic structure of intertidal communities in a time of climate change
- Authors: Lourenço, Carla Sofia Emídio Rodrigues
- Date: 2018
- Subjects: Upwelling (Oceanography) , Intertidal organisms -- Morocco -- Atlantic Coast , Intertidal organisms -- Canary Current -- Effect of water currents on , Intertidal animals -- Canary Current -- Effect of water currents on , Intertidal animals -- Morocco -- Atlantic Coas , Mytilus galloprovincialis -- Morocco -- Atlantic Coast , Mytilus galloprovincialis -- Canary Current -- Effect of water currents on , Intertidal ecology -- Canary Current , Sea surface microlayer -- Morocco -- Atlantic Coast
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61614 , vital:28042
- Description: Upwelling is an oceanographic process that strongly influences coastal species and the communities they belong to. In upwelling areas, colder, denser, nutrient-rich subsurface waters are transported to the nearshore surface, replacing warmer superficial waters that are advected offshore. Such effects influence the composition and dynamics of coastal communities, for example by affecting species abundance, recruitment, dispersal and distribution. Upwelling areas are key model regions to study the responses of coastal species to climate change because they are characterized by cooler conditions and experience lower warming rates than adjacent regions. In particular, intertidal rocky shore species are ideal coastal sentinel organisms to study distributional changes driven by climate warming because they inhabit the interface between marine and terrestrial habitats and are exposed to extremely severe environmental conditions. In fact, sharp distributional shifts have been reported for multiple intertidal species as a response to ocean warming. Although some studies have investigated the role of upwelling in influencing abundance and distribution of intertidal species, little is known about its potential as refugia against climate warming and the degree to which upwelling shapes species genetic structure is yet not fully understood. The aim of this thesis is to understand the influence of the Canary Current upwelling system on intertidal community composition, including species distribution and the genetic structure of intertidal species under current climate change. To do this, I investigated community structure of intertidal assemblages along the Atlantic shores of Morocco and Western Sahara, performed large scale surveys on species distribution, evaluated species abundance and frequency of parasitism and examined species genetic patterns. I further coupled biological data with upwelling indices, sea surface temperatures (SST) and the rate of SST warming. I demonstrate that strong upwelling influences abundance and distribution of intertidal rocky shore species and that upwelling cells can act as refugia from climate change by ameliorating thermal conditions. Upwelling cells also conserve the genetic diversity of the marine macroalga Fucus guiryi, promoting intraspecific genetic diversity by preserving unique genetic lineages. However, no evidence was found that upwelling affects the genetic structure for either F. guiryi or the brown mussel Perna perna. Instead, the genetic patterns presented in this thesis seem to result from a combination of species’ life history traits, population size and habitat suitability. My results also suggest that upwelling intensity affects the frequency of endolithic parasitism on the Mediterranean mussel Mytilus galloprovincialis. In times of climate change, upwelling events provide suitable environmental conditions for species to counter act climatic change. As upwelling is project to intensify in the future, its influence on benthic intertidal species might be greater than previously anticipated.
- Full Text:
- Date Issued: 2018
The role of transformative mediation in post-electoral violence: the case of Kenya 2007-2008
- Authors: Ondigo, Anne Achieng Oyier
- Date: 2016
- Subjects: Political violence -- Kenya Conflict management -- Kenya
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12962 , vital:27138
- Description: Free and fair elections, accompanied by smooth transitions of democratically elected leaders, constitute one of the key pillars of democracy. The dawn of democratisation and advent of multi-party politics after the end of the Cold War in 1991, seemingly held great promise for Africa. However, in recent years, many elections in Africa have consistently become a source of violence. Electoral violence is threatening to become an intractable source of conflict on the African continent, making it hard for emerging democracies to consolidate their status as free democratic societies. Many remain largely autocratic or semi-democratic. African leaders are all too often not ready to relinquish political power, while political elites are ‘power hungry’ and use violence to skew the outcomes of elections in their favour. Hence, electoral violence is employed in order to manipulate civilian election choices and outcomes. Election violence is often deliberately used to target civilians, and in countries like Kenya involves inter-ethnic clashes. These “new wars” are fought unconventionally using ‘crude weapons’, (Kaldor 2013). Kaldor describes how these ‘new wars’ are fought as intra-state (within the state) wars in developing countries. Often, they are waged via state or county networks based on identity or ethnicity. The consequences of electoral violence include the destruction of property, reversed development, injuries, rape, death, internally displaced persons and refugees. Electoral violence persists despite attempts to contain it and measures to effectively manage these processes often prove to be inadequate. The study utilises an exploratory case study of Kenya during 2007-2008 Post-Election violence. The causes, the immediate steps that were initiated to mitigate violence and the reforms undertaken to generate peace structures and prevent future occurrences of post-election violence were explored. Forty-five participants representing involved citizens, negotiators and mediators were interviewed. The research was triangulated via the interview process, together with the use of primary document analysis and an extensive review of the literature. The data was analysed via the use of grounded theory. The research findings reveal that the causes of electoral violence are multi-faceted and multi-layered, with deep underlying issues. The causes include weak institutions, corruption, a non-representational electoral system, ethnicity and ethnic militia. Further causes include statelessness as experienced by certain groups, abuse of state resources and human rights violations. The role of political elites who withhold crucial information, thus denying the public the opportunity to make informed choices during elections was also found to contribute to electoral violence. Other information-related causes include biased media and sensational reporting. Findings also show that socio-economic issues such as poverty, unemployment, scarce resources and unmet basic human needs cannot be underestimated. Lastly, the causes of electoral violence included diverse interests of internal and external actors at play during elections. The findings revealed that although the Kenyan mediation process included the signing of a peace agreement, the root causes of electoral violence such as corruption, weak institutions, abuse of state resources and the unjust electoral system were not adequately addressed. A model for mediation for electoral violence which was explored and developed sought to build on the strengths of the Kenyan mediation process and address its inherent weaknesses, thus making this a significant contribution flowing from the study. The election model for mediation proposes certain key phases which include a pre-mediation process that will ensure a cessation of all hostilities; the mapping of the root causes of electoral violence and electoral reforms that provide resolutions that are acceptable to all the parties. Training of personnel at all levels of government to implement these reforms is also proposed. These measures can ensure the integrity and independence of electoral institutions from political manipulation. Training constitutes a crucial stage in the process of consolidating the emerging democracies. The model for mediation developed is therefore not only meant to mitigate electoral violence but is also intended to serve as a preventive measure. Many African states currently experience structural weaknesses similar to those that existed in Kenya before the 2007-2008 elections (and still persist). These fault lines include corruption, weak institutions, human rights violations, and lack of information. The proposed model for mediation which aims to counter these problems can thus be applied and adapted for implementation in Africa and globally. Several recommendations with implications for policy development are proposed to curb electoral violence. They include constitutional reforms, training of government and electoral officials and the introduction of a properly representational election system. This study, which focuses specifically on post-election violence, recommends further research investigating the pre-election phase, and ‘voting day’ causes of electoral violence for a more comprehensive approach to electoral violence research.
- Full Text:
- Date Issued: 2016
The role of the self-concept in a system of guidance at the level of initial adolescence
- Authors: Hall, Deryck John
- Date: 1987
- Subjects: Self-perception in adolescence , Educational counseling
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1382 , http://hdl.handle.net/10962/d1001448
- Description: Part One I A Perspective on Guidance II Concepts of Self This section is a review and discussion of the two conceptualizations which are fundamental to the research structure: guidance as an overall framework within which procedures are devised for the development of this understanding of the "self" . Part Two • III Didactic Discovery IV The Class Citation Award A way of thinking about an ~ducational approach which could generate a classroom mileu, where the in a practical ongoing process to encourage participation and CCA is the key~ote strategy involve the group in "self" and "other" awareness. Part Three V VI Experiment, Survey, Action Research Results, Reflections and Recommendations The three research methods employed to gather evidence of pupil awareness and its implications, with a discussion patterns of self~knowledge, and its effect on the NOTE: Constant reference to thi s page, and to page xxxii will enable the reader to view the thesis as a whole
- Full Text:
- Date Issued: 1987
The role of the queen in wax secretion and comb building in the Cape honeybee, Aps mellifera capensis (Escholtz)
- Authors: Whiffler, Lynne Anne
- Date: 1992
- Subjects: Honeybee Honey, Comb Beeswax Bee culture -- Queen rearing
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5763 , http://hdl.handle.net/10962/d1005451
- Description: The role of the queen in wax secretion and comb building was studied in the the Cape honeybee, Apis mellifera capensis (Escholtz). The percentage of bees bearing wax and the amount of wax borne by these bees did not differ between the experiments. This meant that the queenless and queenright colonies had the potential to construct equal amounts of comb as the amounts of wax available for comb building was the same. Contrary to this prediction, queenright colonies constructed 8 times more comb than their queenless counterparts. Queenright Apis mellifera scutellata colonies constructed 4 times more comb than their queenless counterparts. The increased amount of 9-oxo-2-decanoic acid (90DA) in the A.m.capensis mandibular gland secretions could not alone account for this difference. In fact, A.m.capensis and A.m.scutellata colonies constructed similar amounts of comb when they were given their own queens or queens from the other race. Worker bees need to have direct contact with their queen for comb building to be enhanced. Even when the queen had her mandibular glands extirpated and tergite glands occluded large amounts of comb were constructed than when access to the queen was limited. Direct access to the head of a mated queen proved to be the stimulus enhancing comb building. No comb was constructed when the workers had access to the abdomen of the queen. Virgin queens did not stimulate comb building. The relatively large amounts of 90DA and 9HDA from the mandibular glands of Cape virgin queens had not influenced comb building. Worker sized cells were generally constructed. These cells were slightly smaller than those constructed by European honeybees, but were indicative of African bees. A few queen less colonies constructed cells that were of an intermediate drone and worker size. Four mandibular gland pneromones were measured by gas chromatography. No correlations between these pheromones and the comb construction measurements were found. It is unlikely that the mandibular gland pheromones are the only pheromones that stimulate comb building. Pheromones from other glands on the head may contribute towards the enhancement of comb building, and they are not present in virgin queens
- Full Text:
- Date Issued: 1992
The role of the office of the auditor general of South Africa in enhancing sound public financial management, with special references to the Eastern Cape Province
- Authors: Deliwe, Mawonga Christopher C
- Date: 2016
- Subjects: South Africa -- Office of the Auditor-General Finance, Public -- South Africa -- Auditing Auditing -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/2017 , vital:27596
- Description: The 1996 Constitution of South Africa and the Public Audit Act of 2004 provide the legislative framework for the Office of the Auditor General of South Africa (OAGSA). The Independent Regulatory Board for Auditors further enriched the interpretation of the framework – for government auditing. Over the years of democratic rule in South Africa, audit performance by State organs was generally poor. Despite the efforts by the OAGSA to improve the performance, very little improvement was notable. Most disturbing was the observation that there was widespread, a prevalence of recurring findings, which indicated that the OAGSA’s recommendations and guidelines were not acted upon, or largely ignored. Firstly, the research study established that the system of capitalist democracy, which comes in different varieties throughout world democracies, indeed brought about a situation where the electorate was effectively removed from its rightful place of being the principal, and had its place taken up by political parties (which are in fact, agents) - which (parties) governed on its (the electorate’s) behalf. This system, taken together with the Principal Agency and the Rational Choice Theories – fully explained the prevalence of maladministration and malfeasance in government in South Africa. Secondly, the study established that the OAGSA has done everything imaginable in its attempts to improve audit performance in government institutions – using the carrot rather than the stick approach. The legislative framework cited above, revealed that the OAGSA has the power to audit and report, while Parliament has the power to enforce corrective action. The lesson of this revelation is: that there is not much that the OAGSA can achieve without a high level of cooperation between itself and Parliament – if audit performance is to be effectively, and appreciably improved in South Africa. A disappointing discovery however was indirectly delivered to the world, through the results of a research study conducted by one Wehner in 2002, on Public Accounts Committees (PACs) (alias Standing Committees on Public Accounts (SCOPAs)) in world democracies. The Wehner study clearly demonstrated that there was nothing contained in these committees’ founding documents or enabling legislation – which in no uncertain terms, directed the committees on what procedures and processes to follow to ensure that their resolutions were acted upon. In other words there was no enforcement mechanism discernible for their resolutions. Thirdly, there were developments in case law in South Africa, which augured well for Constitutional Institutions in general. They are contained in court judgements relating to the mandate of the Office of the Public Protector (OPP). The question at the core of these developments was: whether the decisions or remedial action emanating from the OPP, were binding and enforceable. Two judgements cited as cases in point, one a High Court judgment and another a Supreme Court of Appeal’s (SCA’s), feature in the research report. The SCA, in summary found that decisions of administrative bodies of State – stand in fact and in law, until such time that a court of law invalidates them. The SCA ruled through citing a High Court judgement passed way back in 2004 - that Constitutional Institutions, although not organs of State per se – were certainly included in this 2004 finding, if one considers the rationale of this initial finding, taken together with the purpose for which Constitutional Institutions were established in South Africa in the first place. In conclusion, although visible root causes of poor audit findings appear overall to be poor consequence management and questionable leadership quality in government, the system of capitalist democracy is ultimately to blame. The system certainly had unintended consequences.
- Full Text:
- Date Issued: 2016
The role of the mite Orthogalumna terebrantis in the biological control programme for water hyacinth, Eichhornia crassipes, in South Africa
- Authors: Marlin, Danica
- Date: 2011
- Subjects: Water hyacinth -- Biological control -- South Africa Aquatic weeds -- South Africa Invasive plants -- South Africa Mites -- South Africa Mites as biological pest control agents -- South Africa Biological pest control agents -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5762 , http://hdl.handle.net/10962/d1005450
- Description: Water hyacinth (Eichhornia crassipes) is an aquatic macrophyte originating from the Amazon basin. Due to its beautiful appearance it has been introduced into numerous countries across the world as an ornamental pond plant. It was introduced into South Africa in the early 1900s and has since reached pest proportions in many of the country’s fresh water bodies, causing significant economic and ecological losses. It is now considered to be the worst aquatic weed in South Africa. Efforts to control the spread of the weed began in the early 1970s and there have been some successes. Biological control has been used widely as an alternative to mechanical and chemical controls because it is cost-effective, self-sustaining and environmentally friendly. To date, six biological control agents have been introduced onto water hyacinth in South Africa. However, due to factors such as cold winter temperatures and interference from chemical control, the agent populations are occasionally knocked-down and thus the impact of biological control on the weed population is variable. In addition, many South African water systems are highly eutrophic, and in these systems the plant growth may be accelerated to such an extent that the negative impact of the agents’ herbivory is mitigated. One of the agents established on the weed is the galumnid mite Orthogalumna terebrantis, which originates from Uruguay. In South Africa, the mite was initially discovered on two water hyacinth infestations in the Mpumalanga Province in 1989 and it is now established at 17 sites across the country. Many biological control researchers believe that the mite is a good biological control agent but, prior to this thesis, little quantitative data existed to confirm the belief. Thus, this thesis is a post-release evaluation of O. terebrantis in which various aspects of the mite-plant relationship were investigated to determine the efficacy of the mite and thus better understand the role of the mite in the biological control programme of water hyacinth in South Africa. From laboratory experiments, in which mite densities were lower than densities occurring in the field, it was found that water hyacinth growth is largely unaffected by mite herbivory, except possibly at very high mite densities. When grown in high nutrient conditions the growth of the plant is so great that any affect the mite has is nullified. Plant growth is thus more affected by nutrients than by mite herbivory. However, mite feeding was also influenced by water nutrient levels and mite herbivory was greatest on plants grown in high nutrient conditions. The presence of the mite had a positive effect on the performance of the mirid Eccritotarsus catarinensis, such that the interactions of the two agents together had a greater negative impact on the plant’s growth than the individual agents had alone. Furthermore, water hyacinth physiological parameters, such as the plant’s photosynthetic ability, were negatively impacted by the mite, even at the very low mite densities used in the study. Plant growth rate is dependent on photosynthetic ability i.e. the rate of photosynthesis, and thus a decrease in the plant’s photosynthetic ability will eventually be translated into decreased plant growth rates which would ultimately result in the overall reduction of water hyacinth populations. In addition, temperature tolerance studies showed that the mite was tolerant of low temperatures. The mite already occurs at some of the coldest sites in South Africa. Therefore, the mite should be able to establish at all of the water hyacinth infestations in the country, but because it is a poor disperser it is unlikely to establish at new sites without human intervention. It is suggested that the mite be used as an additional biological control agent at sites where it does not yet occur, specifically at cold sites where some of the other, less cold-tolerant, agents have failed to establish. Finally, conditions of where, how many and how often the mite should be distributed to water hyacinth infestation in South Africa are discussed.
- Full Text:
- Date Issued: 2011
The role of the Hop co-chaperone in the formation of Hsp90 complexes: chaperone link to glycolysis
- Authors: Maharaj, Shantal
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163593 , vital:41051 , doi:10.21504/10962/163593
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020
- Full Text:
- Date Issued: 2020
The role of the euthecosome pteropod, limacina retroversa, in the polar frontal zone, Southern Ocean
- Authors: Bernard, Kim Sarah
- Date: 2007
- Subjects: Pteropoda Limacidae Zooplankton -- Antarctic Ocean Copepoda Phytoplankton
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5761 , http://hdl.handle.net/10962/d1005449
- Description: The aim of the present study was to assess the ecological role of the euthecosome pteropod, Limacina retroversa, in particular, and the mesozooplankton community, in general, in the pelagic ecosystem of the Polar Frontal Zone (PFZ), Southern Ocean. Data were collected from four oceanographic surveys to the Indian sector of the PFZ during austral autumn 2000, 2002, 2004 and 2005. Copepods, mainly Calanus simillimus, Oithona similis, Clausocalanus spp. and Ctenocalanus spp., typically dominated total mesozooplankton counts, accounting for, on average, between 75.5 % and 88.1 % (Mean = 77.4 %; SD = 13.4 %) of the total, during the present investigation. Results of the study indicate that L. retroversa may, at times, contribute substantially to total mesozooplankton abundances. During the study, L. retroversa contributed between 0.0 and 30.0 % (Mean = 5.3 %; SD = 7.1 %) to total mesozooplankton numbers. Significant small-scale variability in abundance and size structure of L. retroversa and abundance of copepods was minimal. Inter-annual variability, on the other hand, was significant between some years. Total pteropod numbers were greatest during April 2002 and 2004, while copepods exhibited greatest abundances during April 2004 only. Pearson’s Correlation analysis suggested that L. retroversa abundances were positively correlated to total surface chlorophyll-a (chl-a) concentrations. The significantly lower chl-a concentrations recorded during April 2005 may explain the reduced pteropod numbers observed during that survey. The size class structure of L. retroversa comprised mainly small and mediumsized individuals during all four surveys. This corresponds well with records from the northern hemisphere (sub-Arctic and Arctic waters) where Limacina spp. are reported to exhibit maximum spawning during mid to late-summer. Higher abundances of large individuals only occurred during April 2005, when chl-a concentrations were very low; possibly the result of delayed spawning, due to reduced food availability. Ingestion rates of the four most abundant copepods, determined using the gut fluorescence technique, ranged between 159.32 ng (pigm) ind⁻¹ day⁻¹ and 728.36 ng (pigm) ind⁻¹ day⁻¹ (Mean = 321.01 ng (pigm) ind⁻¹ day⁻¹; SD = 173.91 ng (pigm) ind⁻¹ day). Ingestion rates of L. retroversa were much higher, ranging from an average of 4 28.68 ng (pigm) ind⁻¹ day⁻¹ in April 2002 to 4 196.88 ng (pigm) ind⁻¹day⁻¹in April 2005 (Mean = 4157.36 ng (pigm) ind⁻¹ day⁻¹; SD = 35.37 ng (pigm) ind⁻¹day⁻¹). Average daily grazing rates for the pteropod varied between 0.39 mg (pigm) m⁻² day⁻¹ in April 2005 and 17.69 mg (pigm) m-2 day-1 in April 2004 (Mean = 6.13 mg (pigm) m⁻² day⁻¹; SD = 11.04 mg (pigm) m⁻² day⁻¹); corresponding average daily grazing impacts ranged between 8.4 % and 139.8 % of the phytoplankton standing stock in April 2005 and 2004, respectively (Mean = 48.5 %; SD = 84.5 %). Average daily grazing rates of the four copepods ranged from 4.58 mg (pigm) m⁻² day⁻¹ to 8.77 mg (pigm) m⁻² day⁻¹ -1, during April 2002 and 2004, respectively (Mean = 6.28 mg (pigm) m⁻² day⁻¹; SD = 5.94 mg (pigm) m⁻² day⁻¹). Collectively, the copepods removed an average of between 31.6 % and 89.8 % of the phytoplankton standing stock per day, during April 2002 and 2004, respectively (Mean = 70.8 %; SD = 86.7 %). The daily grazing impact of the copepods accounted for an average of between 40.4 % and 87.8 % of the total zooplankton grazing impact, during April 2004 and 2005, respectively (Mean = 75.0 %; SD = 65.5 %). L. retroversa was responsible for an average of 52.4 % and 59.5 % of the total zooplankton grazing impact, during April 2002 and 2004, respectively. However, during April 2005, when L. retroversa numbers were significantly lower than previous years, the pteropod contributed an average of only 7.5 % to the total zooplankton grazing impact. Thus, during the present investigation,the pteropod was responsible for removing a mean of 48.9 % of the available phytoplankton (SD = 74.9 %). The predation impact of the dominant carnivorous macrozooplankton and micronekton in the PFZ was determined during April 2004 and 2005 using daily ration estimates obtained from the literature. Additionally, gut content analysis was used to determine the contribution of L. retroversa to the diet of the dominant predators. Average predation impact ranged from 1.1 % and 5.7 % of the total mesozooplankton standing stock during April 2004 and 2005, respectively (Mean = 3.8 %; SD = 12.3 %). Chaetognaths and euphausiids dominated total carnivore numbers and made the greatest contributions to total predation impact during both years. Copepods appeared to be the main prey item of the dominant carnivorous macrozooplankton-micronekton in the region. L. retroversa was only detected in the gut contents of the amphipod, Themisto gaudichaudi, but not in either of the chaetognath species (Eukrohnia hamata and Sagitta gazellae) or the myctophid fish (Electrona spp.). The pteropod was found in 19 % of amphipod guts dissected. Pearson’s Correlation analyses showed that the four major predatory zooplankton groups found in the PFZ (chaetognaths, euphausiids, amphipods and myctophid fish) were positively correlated to abundances of L. retroversa, suggesting that the pteropod might be an important prey item for many of the carnivorous macrozooplankton/micronekton in the PFZ. To conclude, L. retroversa may play an important role in the pelagic ecosystem of the PFZ, in austral autumn. However, ocean acidification and calcium carbonate undersaturation (as a result of increased anthropogenic carbon dioxide emissions), that is predicted to occur within the next 50 – 100 years, will most likely have significant implications for the Sub-Antarctic pelagic ecosystem if L. retroversa cannot adapt quickly enough to the changes.
- Full Text:
- Date Issued: 2007
The role of the deep spawning grounds in chokka squid (Loligo reynaudi d'orbigny, 1845) recruitment
- Authors: Downey, Nicola Jean
- Date: 2014
- Subjects: Squids -- Spawning -- South Africa Squids -- Effect of temperature on -- South Africa Squids -- Embryos -- South Africa Squids -- South Africa -- Geographical distribution Loligo -- Research -- South Africa Loligo fisheries -- South Africa Recruitment (Population biology) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5359 , http://hdl.handle.net/10962/d1011867
- Description: It was previously thought that the South African chokka squid Loligo reynaudi is exclusively an inshore, shallow water spawner. Although spawning mostly within shallow bays (<60 m) the presence of squid eggs in trawls at depths up to 130 m indicates this species frequently makes use of deeper spawning areas on the mid-shelf. The extent of mid-shelf spawning (referred to as deep spawning) and the contribution to recruitment has yet to be assessed. Studies have shown mid-shelf bottom temperature to vary considerably from those inshore, suggesting chokka squid spawn in two very different oceanographic environments. Considering these apparent environmental differences, what leads to the mid-shelf environment becoming a suitable spawning habitat? Does a suitable benthic habitat, required for the attachment of egg pods, occur on the mid-shelf? These questions are not only important for determining the extent of deep spawning, but also to the understanding of factors “driving” deep spawning. The fate of deep spawned hatchlings is another unknown. It has been proposed that the main chokka squid inshore spawning grounds are positioned to exploit the net westward currents on the Eastern Agulhas Bank, i.e. paralarvae would be transported west from the hatching site to the cold ridge, an area of high primary and secondary productivity on the Central Agulhas Bank. This concept has come to be known as the Western Transport Hypothesis. Lagrangian ROMS-IBMs (regional ocean model system – individual-based model) predict the net westward transport of paralarvae from both the inshore and deep spawning grounds, to the cold ridge. These simulations were used to investigate the transport of hatchlings to the cold ridge feeding grounds before the exhaustion of yolk reserves. The fate of paralarvae on reaching the feeding grounds has not yet been investigated. This work has contributed new knowledge to our understanding of deep spawning and its role in recruitment. Specific aims of this study were to (1) determine the extent, range and importance of the deep spawning grounds relative to those inshore; (2) investigate the deep spawning ground habitat (Agulhas Bank mid-shelf) morphology and oceanographic environment; (3) determine the transport and survival of deep spawned hatchlings; and (4) investigate the origin and distribution of chokka squid paralarvae on the Agulhas Bank. The extent, depth range and importance of the deep spawning grounds, relative to those inshore was assessed using 23 years of demersal trawl survey data. Data for both the west and south coasts of South Africa were examined for egg capsules. No spawning was found on the west coast. Data showed that chokka squid preferred the Eastern Agulhas Bank for spawning. Spawning occurred not only inshore but also on the mid-shelf extending to depths of 270 m near the shelf edge. The majority of deep spawned eggs however, were found in the depth range 71-130 m. Squid egg density markedly decreased beyond 70 m, suggesting delineation between the inshore and deep spawning grounds. Total egg biomass calculations for depths shallower and deeper than 70 m indicated the coastal area to be strongly favoured, i.e. 82 vs. 18%. These results contest the commonly accepted notion that chokka squid is an inshore spawner and redefine the spawning grounds to extend across the shelf. Apart from an initial study investigating bottom temperature on the mid-shelf, very little is known about the deep spawning habitat. St Francis Bay, a commonly used spawning location, was chosen as a demonstration area for further study. The deep spawning grounds (71-130 m) were mapped and benthic habitat described from underwater video footage. A study investigating cross-shelf bottom conditions was undertaken off Thys Bay. CTD data were used to compare seasonal bottom temperature and oxygen on the St Francis Bay inshore and deep spawning grounds. Squid movement between the two spawning habitats was assessed using filament tagging. Predation and fishing pressure across the spawning grounds was reviewed. The mid-shelf benthic habitat was found to be similar to that inshore and available for spawning. Despite the generally colder bottom temperatures on the mid-shelf, this study showed that bottom temperature in deeper waters can at times be warmer than inshore. Although mid-shelf warming events lasted from a few hours to a number of days, they resulted in similar conditions to those on the inshore spawning grounds. It is likely these events act to expand or shift spawning habitat. The movement of squid between the two spawning habitats makes it possible for them to seek patches of warm bottom water with appropiate substrate. This suggests they are spawning habitat opportunists. Predation and fishing pressure appear to be higher on the inshore spawning grounds. It is feasible that this also forces spawners to seek out more favourable habitat offshore. An individual-based model was used to predict the fate of mid-shelf and inshore hatched paralarvae. Within the model, both the highly productive cold ridge and inshore spawning grounds were considered feeding or nursery areas. Paralarvae were released from six inshore and six deep spawning sites, spanning the coast between Port Alfred and Knysna. All paralarvae not reaching the feeding areas before the exhaustion of yolk-reserves (≤5 days), not retained within the feeding grounds (≥14 days), and not retained on the Agulhas Bank after exiting the feeding grounds were considered lost. This work illustrated the dependence of paralarval transport success on both spawning location and time of hatching, as established in earlier studies. The current IBM has expanded on initial work, emphasizing the importance of the cold ridge and inshore spawning grounds as nursery areas for deep and inshore spawned paralarvae, respectively. This work has highlighted the complex interactions between processes influencing recruitment variability for chokka squid. Possible relationships between periods of highest recruitment success and spawning peaks were identified for both spawning habitats. Based on the likely autumn increase in deep spawning off Tsitsikamma, and the beneficial currents during this period, it can be concluded deep spawning may at times contribute significantly to recruitment. This is particularly true for years where the cold ridge persists into winter. Data on chokka squid paralarval distribution are scarce. Paralarval distribution and abundance, in relation to Agulhas Bank oceanography, was investigated using bongo caught paralarvae and corresponding oceanographic data. Individual-based models (IBMs) were used to predict the origin or spawning site of the wild caught paralarvae, with reference to inshore versus deep spawning. Although failing to predict realistic points of origin, this study provided evidence to support a number of scenarios previously assumed to influence chokka squid recruitment. First is the possible influence of coastal upwelling on the retention, and hence spatial distribution, of paralarvae on the inshore spawning grounds. The second factor thought to impact recruitment is the loss of paralarvae from the Agulhas Bank ecosystem. This study confirmed the removal of paralarvae from the Eastern Agulhas Bank due to Agulhas Current boundary phenomena and resultant offshelf leakage. In addition, data suggested that the formation of the cold ridge could enhance retention on the Central Agulhas Bank, and so prevent offshelf leakage from the Central and Western Agulhas Bank. A synthesis of the main conclusions is presented. Implications of the findings and directions for future research are discussed.
- Full Text:
- Date Issued: 2014
The role of the church in social development : the case of selected churches in Nairobi, Kenya
- Authors: Mutunga, Daniel Kioko
- Date: 2018
- Subjects: Perception Social action Community development
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/12599 , vital:39291
- Description: The church as a unique society was founded by Jesus Christ who also set a pattern for its operations. Primary to the core responsibilities of the church, according to Scripture, is to reconcile creation to the Creator by transforming society to regain its lost nature. The Christian Church in Kenya was established by missionaries from different parts of the world about three centuries ago. It has since grown and spread to almost all the parts of the country, but all the major denominations have vibrant congregations in Nairobi. A quick categorisation of the church in Kenya would be into the Mainline and the Pentecostal churches. This study set out to investigate the perception the church in Nairobi holds on in its involvement in social action, whether the church thinks social action is part of its ministry, and what kind of engagements in social action the church in Nairobi is currently having. The study employed a qualitative approach and an exploratory design. Using the questionnaire and interview methods, data was collected from thirty two (32) church leaders (including pastors) sampled to be representative of the Mainline and the Pentecostal groups of churches. The data was transcribed, coded, categorised and interpreted following the themes which emerged in relation to the study objectives and the nature of the responses. The results of the study show that the church holds different perceptions on its responsibility and involvement with regard to social action. The findings show two extremes: those who see social action as core to the mission of the church and those who think social action is the responsibility of the government or of non-governmental agencies. Generally most churches do not plan or budget for social actions. The few that are engaged in in it the budgets are far too low compared to the other church activities and the plans are unstructured and sporadic Active engagement in social action by the church in Nairobi is therefore, by and large, unplanned and episodic. However, the few who are already engaged in social action have witnessed great success in community transformation. The study concludes that the church has not fully understood its ministry and this could be the reason why social action is not part of its agenda. This further explains the sporadic and truncated nature of social action in the church in Nairobi. The study recommends a review of the curriculum in seminaries and the retraining of practising pastors to embrace holistic ministry. This will address the current misconceptions, address the current dichotomy of sacred-secular in church ministry, and hence increase organised participation of the church in social action.
- Full Text:
- Date Issued: 2018
The role of small antelope in ecosystem functioning in the Matobo Hills, Zimbabwe
- Authors: Lunt, Nicola
- Date: 2011
- Subjects: Antelopes -- Zimbabwe -- Rhodes Matopos National Park Ecosystem health -- Zimbabwe -- Rhodes Matopos National Park Forest ecology -- Zimbabwe -- Rhodes Matopos National Park Savanna ecology -- Zimbabwe -- Rhodes Matopos National Park Woody plants -- Effect of fires on -- Zimbabwe -- Rhodes Matopos National Park Duikers -- Zimbabwe -- Rhodes Matopos National Park Bushbuck -- Zimbabwe -- Rhodes Matopos National Park Greater kudu -- Zimbabwe -- Rhodes Matopos National Park
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5760 , http://hdl.handle.net/10962/d1005448
- Description: The 28-month study assessed the impacts of five syntopic medium-sized mammalian browsers and one fire event in a woodland savanna in the Matobo Hills, Zimbabwe. Aspects of herbivory, mechanical pressures, seed dispersal and nutrient cycling were investigated for three species of small antelope (common duiker [Sylvicapra grimmia]1, klipspringer [Oreotragus oreotragus] and steenbok [Raphicerus campestris]) and two medium-sized species (bushbuck [Tragelaphus scriptus] and greater kudu [T. strepsiceros]). Focusing on Burkea africana2 woodland, in a system that does not include elephant (Loxodonta africana), effects of browsing antelope on woody and herbaceous vegetation development were investigated using exclusion plots. Browsers regulated woody plant cover (measured as basal stem area), with smaller antelope having a greater impact than larger species. This was linked to feeding height, feeding selectivity and mechanical pressures (e.g. twig breakage and trampling). Fire caused an initial reduction in above-ground standing biomass, but in the presence of fauna, pre-fire equilibria were attained within 15 months. In antelope exclosures, herbaceous biomass increased and woody biomass decreased following fire. Responses by woody vegetation to browsing varied among species, with highly palatable species typically exhibiting compensatory regrowth. Woody species richness and abundance (especially of palatable species) increased in the absence of browsers, but species richness of the herbaceous layer was promoted by moderate disturbance (trampling or fire). Faecal deposition behaviour, primarily the use of latrines by small antelope, resulted in localised soil enrichment within defended territories. Decomposition rates (and therefore return of nutrients to the soil) varied among species and seasons, due to defecation site selection, accessibility to decomposers and desiccation rates of faecal pellets. Controlled seed germination experiments indicated that ingestion by small antelope enhances germination rates of large, hard-seeded fruits such as Sclerocarya birrea. However, germination of savanna seeds may require multiple cues. This study demonstrated the critical roles of small antelope in ecosystem functioning, and highlights the importance of the less visible impacts of frequently overlooked smaller mammalian herbivores. Perturbations to the faunal community, especially small antelope, are predicted to have substantial impacts on woody plant cover.
- Full Text:
- Date Issued: 2011