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Phototransformation of pollutants using lutetium and zinc phthalocyanines anchored on electrospun polymer fibers

  • Authors: Zugle, Ruphino
  • Date: 2013
  • Subjects: Electrospinning Phthalocyanines Lutetium Zinc Polymers Dysprosium Pollutants Air Pollution Photochemistry
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4286 , http://hdl.handle.net/10962/d1002962
  • Description: Novel lanthanide phthalocyanines containing dysprosium, erbium and lutetium as central metals were synthesized using phthalonitrile:metal salt ratio of 4:1 or lower phthalonitrile content as well as using unmetallated phthalocyanine. They were characterized using various spectroscopic and elemental analyses. Dysprosium bis-phthalocyanine was obtained while monomers were obtained for erbium and lutetium phthalocyanines. Theopen-shelldysprosiumbis-phthalocyanine and the monomeric complex of the open-shell erbium were neither fluorescent nor showed the ability to generate singlet oxygen. The triplet states of all the lutetium phthalocyanines were found to be populated with high triplet quantum yields and corresponding high singlet oxygen quantum yields. The fluorescence quantum yields of the lutetium phthalocyanines were however found to be very low. The lutetium phthalocyanines together with unsubstituted zinc phthalocyanine and its derivatives were successfully incorporated into electrospun polymer fibers either by covalent linkage or sorption forces. Spectral characteristics of the functionalized electrospun polymer fibers indicated that the phthalocyanines were bound and their integrity maintained within the fiber matrices. Most importantly the fluorescence and photoactivity of the phthalocyanines were equally maintained within the electrospun fibers. The functionalized electrospun polymer fibers especially those containing the zinc phthalocyanines could qualitatively detect nitrogen dioxide, a known environmental air pollutant. Also all the functionalized electrospun polystyrene and polysulfone fibers containing lutetium and zinc phthalocyanines could be applied for the photoconversion of 4-chlorophenol, 4-nitrophenol and methyl orange. Those of polystyrene could be re-used. Polyacrylic acid and polyurethane functionalized electrospun fibers were found not to be suitable for photocatalytic applications in aqueous medium. 4-Chlorophenol was found to be more susceptible to photodegradation while methyl orange very difficult to degrade.
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  • Date Issued: 2013

Neurocognitive effects of head and body collisions on club level rugby union players

  • Authors: Zoccola, Diana
  • Date: 2015
  • Subjects: Head -- Wounds and injuries -- Psychology , Neuropsychological tests , Head -- Wounds and injuries , Sports injuries -- Psychological aspects
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:3257 , http://hdl.handle.net/10962/d1016397
  • Description: The objective of the study was to investigate the cumulative neurocognitive effects of repetitive concussive and subconcussive events in club level Rugby Union (hereafter rugby) during the course of one rugby season, in a combined group and individualized case-based approach. Amateur adult club level rugby players (n = 20) were compared with a non-contact control group (n = 22) of equivalent age, years of education and estimated IQ (p = > .05, in all instances), although the two groups were clearly differentiated on the basis of a history of reported concussions (p = < .05). Video analyses documented the tackling maneuvers observed amongst the players during all matches across the rugby season revealing a sobering average of more than a thousand tackles per player, excluding any contact practice sessions. Five rugby players (n = 5) who were observed to have a head jarring event were also isolated for individualized postconcussive follow-up analysis of their neurocognitive profiles. Measures included the ImPACT Verbal and Visual Memory, Visual Motor Speed and Reaction Time composites and the Purdue Pegboard. Independent and dependent statistical analyses were employed to compare the rugby versus control group neurocognitive test profiles at and between the three test intervals. Correlational analyses explored the association between concussion, tackling and neurocognitive test outcomes. Descriptive comparisons of individual neurocognitive test scores with normative data were employed for the case analyses. Taken together, the results implicated vulnerability amongst club rugby players on the motor and speeded tasks, with less robust indications on the memory tasks. While limited in terms of its small sample size, it is considered that the outcome of the study was rendered more robust by virtue of being methodologically multifaceted with heuristic implications for future research studies in the area. The novel inclusion of tackling data as well as fine-tuned case analyses, were of particular relevance in that regard. The results add to a growing body of literature that implicates deleterious neurocognitive effects in participants of a sport such as rugby due to repetitive head jarring incidents that are intrinsic to the game.
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  • Date Issued: 2015

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

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

Implementation of strategies used to manage conflict between students and staff in secondary schools in Malawi : towards a comprehensive framework

  • Authors: Zimpita, Valentino Tipitana
  • Date: 2018
  • Subjects: Conflict management Conflict management -- Study and teaching Violence -- Prevention
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10353/9412 , vital:34348
  • Description: The study aimed at examining how strategies used to manage conflict between students and staff in secondary schools in Malawi were implemented. This was after it had been noted that conflicts in secondary schools in Malawi usually ended in violence. The study employed a pragmatic research paradigm. In this paradigm, a researcher employs mixed methods approach which collects both quantitative and qualitative data. Using a concurrent triangulation mixed method design, the two types of data were collected concurrently and analysed simultaneously. Study participants were head teachers, teachers, students, education officials and parents. Most of the teachers were randomly sampled while a few other teachers, the head teachers, the education officials and the parents were purposefully sampled. The study found that there were various causes of conflict in secondary schools in Malawi which included misunderstanding of human rights, poor communication between students and staff, poor school management by head teachers and lack of students‘ involvement in decisions that concerned them. The study further found that conflict was in a way beneficial to schools as it was a learning point for both students and staff. However, such benefits were overshadowed by the many evils that violence brought such as disturbing teaching and learning. The study also found that there were two approaches in the way schools managed conflict; engagement of students and calling for police intervention. It transpired that on the overall, stakeholders were aware of different conflict management skills but they did not know how best to use them. In addition, it transpired that stakeholders were not comfortable with win-win approaches to conflict management. This was against a background that the stakeholders were involved in conflict management in different ways. It also came out clear that support to secondary schools in the management of conflict was at two levels; school level and system level. On the part of monitoring, it transpired that the mechanism which were there were ad hoc and they included inspection visits and the requirement that head teachers should always submit reports which could carry issues related to conflict. The study concluded that poorly managed conflicts which turned into violence were a menace to secondary schools in Malawi. In this regard, there was need to ensure effective conflict management in order to avoid violence. To achieve this, the study has made a number of recommendations. Among them, it has been recommended that schools should from time to time take stork of the likely causes of conflict and address them accordingly. It has also been recommended that schools should put in place mechanisms for ensuring two way communication so that students feel free to air out their concerns. At Ministry level, it has been recommended that the MoEST should take guidance and counselling seriously by among other things training teacher councillors and making the post an established one. It has also been recommended that the MoEST should make sure that head teachers, deputy head teachers, teachers, parents and even education officials are inducted in conflict management.
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  • Date Issued: 2018

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

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

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

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

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

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

Removal and recovery of heavy metals from synthetic solutions and electroplating effluents using yeast and the water fern Azolla filiculoides

  • Authors: Zhao, Ming
  • Date: 1998
  • Subjects: Heavy metals -- Environmental aspects Azolla filiculoides -- Biological control Aquatic weeds -- Biological control Yeast Metal ions Yeast fungi -- Biotechnology Cations
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4001 , http://hdl.handle.net/10962/d1004061
  • Description: The aims of the project were twofold. The initial objective of the study, based on previous results, was to develop an economically viable methodology for immobilizing yeast cells for the treatment of heavy metal-laden waste water. The non-viable yeast cross-linked by 13% (w/v) formaldehyde/1N HNO₃ exhibited satisfactory mechanical strength and rigidity in a continuous-flow column operation. No apparent disruption of the biomass after repeated use was observed. The cost of immobilizing 1kg dry yeast pellets was estimated at less than US$I. Zn uptake capacity of FA-cross-linked pellets, on batch trials, remained similar to that of raw yeast, reflecting that the immobilizing procedure did not hinder its metal removing capacity. In column studies, cation metals were effectively removed by the yeast pellets from aqueous solution at natural pHs, and then recovered completely by washing the pellets in situ with O.1M HCl. The recovered metals were concentrated in such small volumes that recycling or precipitation of them was facilitated. The metal uptake capacity of the regenerated biomass remained constant in comparison with cycle 1, indicating that reuse of the yeast would be possible. In the case of Cr⁶⁺, a gradual breakthrough curve of Cr in the column profile was noted, with a simultaneous reduction of Cr⁶⁺ to Cr³⁺. However, Cr⁶⁺ in the effluent can be markedly minimised either by accumulation onto the biomass or reduction to its trivalent form. Desorption of bound Cr⁶⁺ with either alkali or salt could not accomplish the regeneration of the biomass. A combination of reduction and desorption with FA/HNO₃ appeared promising in regeneration of the saturated biomass at 4°C. The metal sorption capacities of the yeast pellets, on a batch or a fixed-bed system are relatively lower than that of documented sorbents. Apparently more of the yeast pellets would be required for treating a certain volume of waste effluent, than with other sorbents. Therefore Azolla filiculoides was examined as a suitable sorbent for this purpose. This constitutes the second part of the project. Azolla filiculoides, a naturally-abundant water fern, was screened for its metal sorption and recovering capacities, mechanical stability, flow-permeability and reusability. The azolla biomass appeared to have fulfilled the required mechanical criteria during the repeated sorption-desorption column operations. It is water-insoluble and appears flexible under pressure when rinsed with water. These characters are of crucial importance in a continuous-flow system since a column can be operated at high flow rates without apparent compact of the biomass and pressure loss. Therefore, immobilization of the biomass can be avoided. The sorption isotherm data, obtained from batch removal of Cr⁶⁺, showed that the sorption process was effective, endothermic and highly pH dependent. Considerable amounts of Cr⁶⁺ were accumulated at the optimum pHs of 2-2.5. Column sorption of Cr⁶⁺ at a low flow rate and pH of 2.5 showed optimum performance with a total Cr uptake of 50.4mg/g at 60% saturation of the biomass. Removal of Cr⁶⁺ from an electroplating effluent using an azolla column was deemed reasonably satisfactory, although the uptake declined slightly. Desorption of bound Cr⁶⁺ with various desorbents was incomplete, which resulted in a low regeneration efficiency of about 50%. However, removal and recovery of Cr³⁺ using the azolla column was than that of Cr⁶⁺. Desorption of Cr³⁺ from the spent biomass column was accomplished with the recovery of 80% using O.5N H₂SO₄, The regeneration efficiencies for Cr³⁺ removal were up to 90% and demonstrated that the biomass is reusable. Cation metal uptake capacities of azolla, obtained either from batch or column experiments, are reasonably high in comparison with other sorbents. The uptake of Ni or Zn ions from solution is pH dependent showing the optimum pH of around 6 to 6.5, under the current experimental conditions. The sorption kinetics for cation metals was rapid with about 80% of the bound Ni ions being taken up in the first 10 min. The character of rapid binding is extremely important in a column sorption process, especially on a large scale since it favours an optimum uptake of metals at high flow rates. The Ni or Zn uptakes in column sorption were not markedly affected when the flow rates were increased from 80mllh up to 800ml/h for the 5g biomass used. The cation heavy metals removed from waste effluents were recovered in a concentrated solution of small volume. The desorption of bound Ni and Zn ions from the saturated biomass was accomplished with either O.2N HCl or H₂SO₄ that resulted in recoveries of more than 95%. The metals recovered, in the case of Ni and Zn, are identical to that of plating agents ego nickel sulphate or chloride, so that recycling of the metals is possible. An effluent-free, closed loop of Ni or Zn treatment system was proposed, whereby the Ni or Zn ions can be recycled to the plating bath whilst the purified water is fed back to the rinse tanks. Ca and Mg ions, commonly present in the electroplating effluents, appeared to affect sorption of heavy metals by azolla when metal concentrations were relatively low, presumedly through its competitive binding for the shared sites on surfaces of azolla. The data obtained from column sorption of Ni and Zn follows the BDST model well, enabling the application of the model to predicting design parameters for scale-up of the biosorption column system. It is interesting that the values of metal uptake, expressed in molar quantities, obtained on respective single-metal solutions and the multiple metal system, are similar, implying that the mechanisms involved in the sorption of all metal cations are similar and that the binding sites on surfaces of azolla are probably shared by all cation metals. The surface of the biomass provides sites for metal binding estimated in the range of 0.45-0.57mmol/g, based on the current experiments. The biomass has a surface area of 429 m²/g and water retention of 14.3 ml/g. The functional groups on the surface of azolla were partially identified using chemical modification and metal binding comparison. Among the functional groups examined, carboxyl groups, provided by amino acids and polysaccharides, appeared to play an important role in metal cation binding. The infrared spectra of the samples support this conclusion.
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  • Date Issued: 1998

Assessing soil carbon and carbon dioxide effluxes under different vegetation cover conditions in the Eastern Cape Province, South Africa

  • Authors: Zengeni, Rebecca
  • Date: 2013
  • Subjects: Soils -- Carbon content -- Measurement , Carbon dioxide mitigation -- South Africa , Greenhouse gas mitigation -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:10665 , http://hdl.handle.net/10948/d1018676
  • Description: Albany thicket is prevalent in the Eastern Cape Province of South Africa. Its spread has diminished through overgrazing and heavy browsing by animals, land clearance and urban expansion. The result is highly degraded land characterized by invasion of alien species. There is a wealth of documented evidence on the high carbon sequestration ability of thicket biome, but not much has been done to assess its effect on carbon dioxide emissions from the soil. Given that the concentration of atmospheric greenhouse gases has been constantly rising since the industrial era, it is imperative to assess the influence of thicket biome as a source or sink of these gases. There is evidence of shifts in the climate in southern Africa as reflected by changes in rainfall patterns, increased temperatures, recurrent droughts and fires. As such, the historical rainfall variability in an Albany thicket region and its interaction with the temporal land use / cover changes was studied. This served to give some background information about the study area for more detailed study on C and carbon dioxide effluxes in thicket vegetation under different levels of degradation. This study thus aimed to determine the influence of thicket vegetation at various levels of degradation on soil carbon and carbon dioxide fluxes. The impact of plant photosynthetic pathway on soil C residence time and gas effluxes were analysed to elucidate on the land-use and cover patterns occurring in the area. All this was done to shed some light on the role of soil and thicket vegetation on carbon dioxide emissions and C storage in the spectrum of a shifting climate. The main area of research was Amakhala reserve in an Albany thicket in Eastern Cape Province; and it concentrated on three land cover types namely intact thicket, degraded thicket and grassland. The objectives mentioned above were achieved by assessing historical rainfall variability from 1970 to 2010 through trend and time series analysis at nine rainfall stations located at Amakhala reserve, Grahamstown, Bathurst, Port Alfred, Uitenhage and Port Elizabeth. The land use changes that have occurred in the Albany thicket region covering Amakhala reserve, Grahamstown, Bathurst and Port Alfred were also assessed for 1989, 1999 and 2009 through satellite image analysis with Idrisi Andes GIS software; then their interaction with rainfall variability were determined. To elucidate on the vegetation species composition and land use / cover changes that have occurred in the study area, plant biomass as well carbon (C) and nitrogen (N) isotope measurements were done. Plant biomass was assessed for the dominant species through use of pre-existing allometric equations that required data on plant basal diameter, canopy area, stem numbers and height. The plant carbon was then estimated through use of a conversion factor of 0.48 on above-ground biomass, while soil organic C was determined through the modified Walkely - Black method. Carbon and N isotope ratios were determined from the foliar material of three replicate samples of dominant plant species then analyzed through mass spectrometry. Soil carbon dioxide effluxes were then monitored in each of the intact thicket (IT), degraded thicket (DT) and grassland (G) over a 10 month period; by measuring the net carbon dioxide exchange rate (NCER) through the dynamic chamber method. An automated carbon dioxide exchange analyzer, coupled to a soil temperature probe and photosynthetic active radiation (PAR) sensor was used; with NCER measurements taken every 20-30 days. Soil temperature, moisture, penetration resistance and PAR readings were taken during each assay and later used to interpret the NCER. Results showed that long term variability in annual rainfall had a declining trend at Grahamstown (r = -0.59), Uitenhage and Bathurst stations (r = -0.32 at both stations), but was not significant at Amakhala, Port Alfred and Port Elizabeth stations. Most reductions in rainfall occurred in the 1980s and 1990s with the autumn, winter and summer rainfalls, the daily rainfall index and the daily rainfall subclasses of 10 mm and above showing a similar trend. The land use change detection gave a significant increase in proportion of degraded and transformed (moderately degraded) land between 1989 and 2009 with most of the increases occurring from 1989 to 1999, while farmland area decreased by 1.8 percent over the years. Thus the Albany region had over 30 percent of its land occupied by transformed vegetation, with heavy browsing and uncontrolled grazing being attributed to the destruction of pristine vegetation. Land-use change to game ranching and goat pastoralism was attributed to the reduction in farmland. Rainfall variability – land use change linkages were most significant in 1999 that recorded the least rainfall and had the lowest mean, maximum and sum of the NDVI. Grahamstown had the most significant rainfall-NDVI trends as it had the lowest NDVIs in 1999 when rainfall was lowest, the highest NDVI in 1989 when rainfall was highest and moderate NDVIs in 2009 when rainfall was moderate. Vegetation at the IT was characterized by a dense thicket with diverse growth forms of canopy trees, woody shrubs, succulent shrubs and ephemerals which mostly had the C3 type of pathway. This was in contrast with the IT soil isotopy that showed more positive C isotope ratios, indicating a switch between C3 and CAM photosynthesis in original vegetation. Most of the canopy trees had disappeared in the DT to be replaced by herbs, shrubs and grasses. As such, there was a huge difference in isotope ratios between DT plants and soils with the plants having mostly C3 metabolism while the soil showed a predominance of CAM plants in previous vegetation, indicating significant changes in land cover. The G site mostly comprised the grasses Themeda triandra and Panicum maximum and a few herbs. It maintained a dominance of C4 metabolism in both plants and soils showing very little change in species composition over the years. Because of the higher species diversity at IT, its soil organic C was quite high reaching levels of 3.4 percent (i.e. 3.4 t C / ha) in the top 10 cm then decreasing with depth (p < 0.001); but was moderate at DT (1.1-1.3 percent) and very low at G ( 0.5 percent C) (p < 0.001). In the same manner above-ground biomass was highest at IT i.e. 330 000 kg/ha; but was only 22 000 kg/ha in DT and as low as 6 700 kg/ha in G vegetation. High biomass at IT was mostly attributed to the succulent shrub Portulacaria afra and the canopy trees Euclea undulate, Rhus longispina and Schotia afra. This above-ground biomass translated to biomass C amounts of 158 000 kg/ha at IT, 10 600 kg/ha at DT and 3 200 kg/ha at G. Thus the IT had the highest while G the least and DT moderate plant and soil C sequestration ability. In all, the conversion of IT to DT led to a net loss of 147 000 Kg of biomass C / ha and 12 000kg less organic C / ha of land. Soil carbon dioxide effluxes were however variable between seasons as they were affected by differences in soil properties and seasonal weather patterns. High soil moisture levels (up to 16 percent gravimetric moisture) resulted in reduced soil penetration resistance (1 to 4 Kg/cm2) which raised effluxes at G and DT sites (up to 1.2 μmols m-2 sec-1) in winter, while low moisture (2 percent) resulted in hard dry soil (14 Kgm-2 penetration resistance) with suppressed CO2 effluxes in spring (0.2 μmols m-2 sec-1) especially in DT and G soils. Rising temperature generally caused accelerated gas emissions but only when moisture was not limiting (as was the case in IT). Thus the high summer temperatures (up to 40oC) gave lower effluxes especially in DT and G (< 1 μm-2sec-1) due to limited moisture supply (< 10 percent); while the Autumn period that had very high temperature (up to 48 oC) and good moisture (up to 16 percent) saw accelerated soil CO2 emissions (averaging 2 μmols m-2 sec-1) from all cover types. The high biomass and litter fall at IT served as ready substrate for soil respiration as long as moisture was not limiting and temperatures were favourable, while reduced cover at DT resulted in poor moisture conservation and creation of hard dry soils in spring and summer with reduced respiration. It was concluded that the DT had high CO2 effluxes in winter and reduced emissions in summer; while the opposite was true for the IT. All the cover types had minimal CO2 effluxes in spring and accelerated emissions in autumn. The grassland on the other hand was a fairly moderate source or sink of CO2 in most seasons compared with the other two covers. It was observed that an environment of good moisture and low-moderate temperatures (such as that in the winter) minimises effluxes while maintaining good plant productivity. It was concluded that thicket vegetation is a good sink of carbon that should be preserved in its natural condition to optimize its carbon sequestration potential. All three land covers served as sources or sinks of CO2 depending on soil and seasonal conditions. Thus high moisture and low penetration resistance generally increased effluxes of thicket ecosystems. The effect of increasing temperature on effluxes was only significant when moisture was not limiting. Conditions of good moisture and low-moderate temperatures gave reasonable amounts of effluxes while maintaining good plant productivity. Though the dry soil conditions significantly reduced effluxes in all land covers; they were not desirable since they decreased plant productivity and ultimately its C sequestration potential. Moreover, prolonged dry conditions only serve to exacerbate recovery of thicket plants as they increase mortality of canopy species in degraded and transformed areas in comparison with intact thicket.
  • Full Text:
  • Date Issued: 2013

Examining teachers' role in the promotion of child-friendly environments in Zimbabwean secondary schools : implications for teacher professional development

  • Authors: Zendah, Ketiwe
  • Date: 2017
  • Subjects: Education, Secondary -- Zimbabwe Teachers -- Professional relationships School management and organization -- Zimbabwe
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10353/4937 , vital:28810
  • Description: Hostile school environments are a cause of concern and a perennial international educational problem. The UNICEF’s Child-Friendly Schools (CFS) approach is an international intervention meant to safeguard learners against hostile school environments. The CFS approach mandates schools to offer learners environments and conditions that uphold children’s rights and enhance their development to full potential. The purpose of this mixed methods research study, employing a concurrent triangulation design, was to explore the role of teachers in the promotion of CFS environments. Holsti’s (1970) role theory formed the theoretical framework of this study. The research questions focused on teachers’ understanding of the CFS concept, support offered, strategies employed, challenges encountered, and the implications for teacher professional development. The data collection methods were questionnaires, in-depth interviews, and document analysis with school heads, teachers and learners in the seven government urban secondary schools in Mutare district of Manicaland province in Zimbabwe. Quantitative and qualitative data were independently analysed and merged at the interpretation stage through triangulation of results. Major findings reveal that teachers have poor understanding of the CFS concept, are offered moderate support, occasionally employ viable strategies, and are hindered by various factors in the process of promoting CFS environments. The study’s implications for teacher professional development are rooted in identifying sustainable approaches that adequately equip teachers with relevant information, skills and attitudes that ensure the promotion of CFS environments.
  • Full Text:
  • Date Issued: 2017

The retirement funding adequacy of black South Africans

  • Authors: Zeka, Bomikazi
  • Date: 2017
  • Subjects: Retirement income -- South Africa -- Case studies South Africa -- Finance Finance, Personal
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/13338 , vital:27176
  • Description: Despite the importance of retirement planning, many South Africans have been documented as reaching retirement age without adequate retirement funding. A vast amount of research has been conducted on how proper retirement planning can be beneficial for individuals; however, there has been a lack of attention given to researching the retirement planning of black individuals in South Africa. Thus, the primary objective of this study was to identify, investigate and empirically test which factors influence retirement planning, and which aspects of retirement planning influence the retirement funding adequacy of black individuals. After a comprehensive literature review was undertaken on the factors influencing the retirement planning and retirement funding adequacy of individuals, the following independent variables were identified as influencing the mediating variable (Aspects of retirement planning) and the dependent variable (Retirement funding adequacy) in this study: • Financial literacy; • The role of the financial planner; • Family support structure; and • Health status. These independent variables were selected to construct a hypothesised model and research hypotheses, as they have been identified as the prominent factors that influence the retirement planning of black South Africans. Furthermore, these independent variables were used in determining whether they have an influence on the Aspects of retirement planning (incorporating Retirement provisions, Retirement attitudes and Retirement intentions) and, ultimately, improve the Retirement funding adequacy of individuals. In order to establish the influence of the aspects of retirement planning on the retirement funding adequacy of individuals, an empirical investigation was undertaken. A measuring instrument, in the form of a questionnaire, was compiled from secondary literature sources. The respondents were identified though a mixed sampling approach, whereby stratified sampling and convenience sampling were used to attain 441 usable questionnaires that were subjected to statistical analyses. Descriptive statistics, in the form of frequency distributions, were used to summarise Section A and Section B of the measuring instrument. The validity and reliability of the measuring instrument were confirmed by means of exploratory factor analyses (EFA), and Cronbach’s alpha coefficients were also calculated for this purpose. As a result of conducting the EFA, two independent variables (Family support structure and Health status) loaded together, and the factor was renamed accordingly. From the EFA, the independent variables that emerged were The role of the financial planner, Family, health, and financial well-being, and Financial literacy. Furthermore, the EFA revealed that three mediating variables emerged from the mediating variable Aspects of retirement planning. These three mediating variables were consequently named Retirement intentions, Retirement attitudes, and Retirement provisions. There were no eliminated variables in this study. Based on the results of the EFA, some of the definitions of the variables were adapted. Consequently, the hypothesised model and its research hypotheses were adapted to reflect the results of the EFA. The results of the Cronbach’s alphas calculated reported that all the measuring scales used in the questionnaire of the study were reliable. Furthermore, descriptive statistics were also calculated to summarise the sample data, and Pearson’s product moment correlations were calculated to establish the correlations between all the variables used in this study. A multiple regression analysis was used to investigate the influence of the various independent variables on the mediating variables and the dependent variable. Furthermore, structural equation modelling (SEM) was used as the main statistical procedure to test for mediation in the study. SEM was also used to assess and confirm the results of the multiple regression analyses. Based on the results of the multiple regression analyses and SEM, the hypothesised relationships of the study were accepted or rejected. Additionally, the results of SEM revealed that the revised model of the study displayed acceptable model fit. To conclude the empirical investigation, t-tests and an analysis of variance (ANOVA) tests were performed to assess whether the respondents’ perceptions of the variables used in the study differed as a result of the respondents’ demographic information. Furthermore, to establish significant differences between individual mean scores, post-hoc Tukey tests were calculated, and practical significance was assessed by calculating Cohen’s d values. The main empirical results of the study found that statistically significant relationships exist between the independent variables The role of the financial planner and Family, health, and financial well-being, and the mediating variable Retirement intentions. Furthermore, a significant relationship was found between the independent variable Financial literacy and the mediating variable Retirement attitudes. Other significant relationships were present between all the independent variables The role of the financial planner, Family, health, and financial well-being and Financial literacy, and the mediating variable Retirement provisions. The study also established statistically significant relationships between the mediating variables Retirement attitudes and Retirement provisions and the dependent variable Retirement funding adequacy. Statistically significant relationships were also present between the independent variables Family, health, and financial well-being and Financial literacy and the dependent variable Retirement funding adequacy. This study has added to the limited amount of academic literature in the field of retirement planning in South Africa. Through the hypothesised model developed in this study, a significant contribution has been made towards investigating the factors that influence the retirement planning and retirement funding adequacy of black individuals residing in South Africa. This study presents recommendations to black individuals on practical strategies that could help to improve their retirement planning and retirement funding adequacy. Furthermore, suggestions are presented to financial planners and financial institutions, in order to assist black individuals or potential clients to improve their retirement planning and to help ensure that individuals are financially independent when they reach retirement age. It is recommended that financial institutions provide financial products/services that will cater to black South Africans.
  • Full Text:
  • Date Issued: 2017

Investigating the radical democratic potential of social media use by new social movements in South Africa

  • Authors: Zdanow, Carla
  • Date: 2015
  • Subjects: Social media -- South Africa , Social movements -- South Africa , Neoliberalism -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/4310 , vital:20583
  • Description: Since its inception, the internet ‒ and in particular Web 2.0 ‒ have been valorized as potentially revolutionary democratic spaces. Despite the emergence of concerns over the progressively neoliberal orientation and narcissistic effects of the internet, evidence of the radical democratic potential of this media has received considerable attention. This thesis is orientated around both an exploration of such evidence, and a consideration of its relevance for South Africa. In this regard, the thesis commences with an exploration of the neoliberal underpinnings of the internet and the growing translation of dominant neoliberal discourses into the online practices of mainstream liberal democratic politics. Focus then shifts toward the mounting influence of alternative radical democratic positions online, through an investigation of the virtual manifestations of deliberative, autonomous, and agonistic approaches to radical democracy. And following an examination of the online political practices of selected recent global social movements, the primacy of agonism in online expressions of radical democracy is advanced. In turn, resonances and dissonances between the online activity and practices of such global social movements, and the use of the internet and social media by well-known South African new social movements, are explored. Finally, this thesis concludes by recommending a fourfold new media approach through which the agonistic radical democratic potential of the internet can be realized more fully by the new social movements of South Africa.
  • Full Text:
  • Date Issued: 2015

Representation and use of indigenous heritage constructs : implications for the quality and relevance of heritage education in post colonial southern Africa

  • Authors: Zazu, Cryton
  • Date: 2013
  • Subjects: Albany Museum (Grahamstown, South Africa) Cultural property -- Conservation and restoration -- Research -- Africa, Southern Great Zimbabwe (Extinct city) Indigenous peoples -- Material culture -- Africa, Southern Anthropological museums and collections -- Management -- Research -- Africa, Southern Cultural property -- Management -- Research Ethnoscience -- Study and teaching -- Africa, Southern
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:1407 , http://hdl.handle.net/10962/d1002015
  • Description: This study explores representation and use of indigenous heritage constructs with a view to identifying implications thereof for the quality and relevance of heritage education practices in post colonial southern Africa. Framed within a critical hermeneutic research paradigm under-laboured by critical realist ontology, the study was conducted using a multiple case study research design. The data collection protocol was three-phased, starting with a process of contextual profiling, within which insights were gained into discourses shaping the constitution and orientation of heritage education practices at the Albany Museum in South Africa, the Great Zimbabwe Monument in Zimbabwe and the Supa Ngwao Museum in Botswana. The second phase of data collection entailed modelling workshops in which educators engaged in discussion around the status of heritage education in post apartheid South Africa. This highlighted, through modelled lessons, some of the tensions, challenges and implications for working with notions of social transformation and inclusivity in heritage education. The third phase of data collection involved in-depth interviews. Twelve purposively selected research participants were interviewed between 2010 and 2011. Data generated across the study was processed and subjected to different levels of critical discourse analysis. Besides noting how heritage education in post colonial southern Africa is poorly framed and under-researched, this study revealed that current forms of representing indigenous heritage constructs are influenced more by socio-political discourses than the need to protect and conserve local heritage resources. The study also noted that the observed heritage education practices are oriented more towards addressing issues related to marginalisation and alienation of indigenous cultures and practices, than enhancing learners’ agency to manage and utilise local heritage resources in a more sustainable ways. Based on these findings the study recommends re-positioning heritage education within the framework of Education for Sustainable Development (ESD). ESD acknowledges both issues of social justice and the dialectical interplay between nature and culture; as such, it may allow for representation and use of indigenous heritage constructs in ways that expand current political orientations to include sustainability as an additional objective of heritage education. Given that little research focusing on heritage education has been undertaken within southern Africa, the findings of this study provide a basis upon which future research may emerge.
  • Full Text:
  • Date Issued: 2013

A genetic and ecophysiological comparison of co-occuring indigenous (Perna perna) and invasive (Mytilus galloprovincialis) intertidal mussels

  • Authors: Zardi, Gerardo Ivan
  • Date: 2006
  • Subjects: Perna -- South Africa Mytilus galloprovincialis -- South Africa Mussels -- South Africa Mytilidae -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5613 , http://hdl.handle.net/10962/d1003066
  • Description: The Mediterranean mussel Mytilus galloprovincialis is the most successful marine invasive species in South Africa. Its presence has had significant ecological consequences on the intertidal communities of the west coast. On the south coast, M galloprovincialis co-exists and competes with the indigenous intertidal mussel Perna perna in the lower balanoid zone, where they show partial habitat segregation. The upper and the lower mussel zones are dominated by M. galloprovincialis and P. perna respectively while they co-occur in the mid zone. In this thesis M. galloprovincialis and P. perna are compared in terms of their population genetics and their ecophysiology. The success of an invader depends on its ability to react to new environmental factors, especially when compared to indigenous species. The distribution and diversity of intertidal species throughout the world are strongly influenced by periodic sand inundation and hydrodynamic stress. Occupying the lower intertidal zone, P. perna is more strongly influenced by sand (burial and sand in suspension) than M. galioprovincialis. Despite this, P. perna is more vulnerable to the effects of sand, showing higher mortality rates under experimental conditions in both the laboratory and the field. M. galioprovincialis has longer labial palps than P. perna, indicating a better ability to sort particles. This, and a higher tolerance to anoxia, explains its lower mortality rates when exposed to burial or suspended sand. Habitat segregation is often explained by physiological tolerances, but in this case, such explanations fail. The ability of a mussel to withstand wave-generated hydrodynamic stress depends mainly on its byssal attachment strength. The higher attachment strength of P. perna compared to M. galioprovincialis and of solitary mussels compared to mussels living within a bed (bed mussels) can be explained by more and thicker byssal threads. M galloprovincialis also has a wider shell, is subjected to higher hydrodynamic loads than P. perna and shows a higher theoretical probability of dislodgement, this is borne out under field conditions. The attachment strength of both species increased from higher to lower shore, in parallel to a gradient of a stronger wave action. Monthly measurements showed that P. perna is always more strongly attached than M. galloprovincialis and revealed seasonal fluctuations of attachment strength for both species in response to wave height. The gonad index of both species was negatively cross-correlated with attachment strength. The results are discussed in the context of the evolutionary strategy of the alien mussel, which directs most of its energy to fast growth and high reproductive output, apparently at the cost of reduced attachment strength. This raises the prediction that its invasive impact will be more pronounced at sites subjected to low or moderate wave action at heavily exposed sites. The potential of a species for invasion is also determined by the ability of the invader to disperse. Population genetics provide indirect information about dispersal through a direct measurement of gene flow. The low genetic divergence (measured as mtDNA) of M. galloprovincialis confirms its recent arrival in South Africa. In contrast, the population genetics structure of P. perna revealed strong divergence on the south-east coast, resulting in a western lineage (straddling the distributional gap of the Benguela System), and an eastern lineage, with an overlap region of the two on the south coast between Kenton-on-Sea and Haga Haga. This genetic disjunction may be caused by Agulhas Current acting as an oceanographic barrier to larval dispersal, or by different environmental selective forces acting on regional populations. Over the last ten years, M. galloprovincialis has shown a decrease or cessation of its spread to the east in exactly the region of the genetic disjunction in P. perna, again suggesting either an oceanographic barrier to larval dispersal, or increasing selection driven by sharp gradients in environmental conditions.
  • Full Text:
  • Date Issued: 2006

An experimental study of self-regulated learning with mathematically gifted pupils in Nigerian primary schools

  • Authors: Zaram, Gyang Nyam
  • Date: 2017
  • Subjects: Mathematics -- Study and teaching (Elementary) -- Nigeria , Numeracy -- Study and teaching (Elementary) -- Nigeria Gifted children -- Education -- Curricula Gifted children -- Nigeria
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/13381 , vital:27180
  • Description: The purpose of this study was to determine whether gifted pupils can master an enriched advanced level curriculum in mathematics using self-regulated learning strategies. A mathematics curriculum for class five primary school learners in Nigeria was developed for this study. An empirical study was conducted on primary five pupils who were seen to be significantly gifted in mathematics. The study employed the quantitative method of research, that is, the true experimental research. The pre-test, post-test control group design was used. Sixty gifted pupils who participated in a mathematics enrichment programme (MEP) were assigned into two groups of the control group and experimental group with thirty pupils forming each group. The control group was exposed to direct teaching (DT) while the experimental group used self-regulated learning (SRL) strategies. Four teachers served as facilitators in the MEP. The teaching and learning activities were carried out at a higher cognitive level as opposed to the regular curriculum, ensuring that the contents of the MEP were enriched and accelerated. Pupils in both the experimental group and the control group were administered a pre-test, problem-solving exercises, and post-test. These pupils also completed an attitudinal questionnaire to provide feedback about the MEP. The empirical results show that gifted pupils in primary five are capable of self-regulating their own learning through self-monitoring, self-evaluation, and self-reinforcement. The empirical results also show that there is a significant relationship between self-regulated learning, gifted learners, and an enriched advanced level differentiated curriculum as a realistic alternative to the present regular curriculum for gifted pupils in the mainstream of education. The findings further show that the lack of differentiation of instruction, lack of facilities such as libraries, media centres, and support materials contributes to low achievement of gifted pupils. Furthermore, the findings show that pupils were challenged and motivated with the MEP to the extent that they were engaged to think divergently and applied their metacognitive skills in finding solutions to mathematical problems. Therefore, the findings of this study could have significant implications for the future direction of gifted primary school education as well as teacher education. This study has made a significant contribution to the existing body of knowledge for implementing an enriched advanced level curriculum using SRL strategies for mathematically gifted pupils in the mainstream of primary school education.
  • Full Text:
  • Date Issued: 2017

Complex interactions involving the Cape fig, Ficus sur Forsskål, and its associated insects

  • Authors: Zachariades, Costas
  • Date: 1995
  • Subjects: Insect-plant relationships Mutualism (Biology) Fig -- South Africa Fig wasp -- South Africa Ants Homoptera
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5655 , http://hdl.handle.net/10962/d1005338
  • Description: The inadequacy of arbitrarily classifying interactions between species as antagonistic, neutral or mutualistic has become clear in recent years. Both direct and indirect interactions between species can vary between mutualism and antagonism, depending on the intrinsic and extrinsic contexts of the interaction. This study investigated the characteristics of an ant-plant-homopteran interaction in southern Africa. The polyphagous homopteran Hilda patruelis (Tettigometridae) feeds primarily on the trunk-borne fruiting branches and figs of the Cape fig tree, Ficus sur, and produces honeydew which attracts tending ants. Ten of the sixteen ant species/species groups present on F. sur tended H. patruelis, with Pheidole megacephala the most frequent attendant. Ants attracted to F. sur by H. patruelis honeydew or other liquid food sources also preyed on insects on the tree, including adults of the small agaonid fig wasps whose larvae feed on the ovules in the developing figs. One fig wasp species (Ceratosolen capensis) is also the tree's only pollinator. No benefits to H. patruelis from being tended by ants were detected, either in terms of reduced parasitism, or predation by a lycaenid caterpillar. A P. megacephala colony foraging on a F. sur tree was found to receive a high proportion of its likely energy requirements from the tree, mainly in the form of H. patruelis honeydew, during periods when it was bearing fruit. It is probable that the H. patruelis-P. megacephala interaction constitutes a direct mutualism at times, but that benefits to the homopteran are intermittent or weak. Both H. patruelis and ants benefitted from F. sur, directly or indirectly, through the provision of food (and for some ants, nesting sites). The removal of phloem sap by H. patruelis did not detectably reduce the trees' reproductive output, either in terms of pollinator or viable seed production. The indirect effects of ant and H. patruelis presence on the F. sur trees were on average positive, as ants preyed disproportionately heavily on fig wasp species parasitic on or competing with the pollinator, thus increasing pollinator production. Effects of ant presence on seed production were not investigated, but have been demonstrated as beneficial elsewhere. However, there is great varatlon both in the composition of the wasp fauna arriving to oviposit at different crops, and in ant densities per fig, on several temporal and spatial scales. This results in high variability in the effects of ants on the pollinator and, through it, the tree, from positive to zero and potentially even negative. Despite this conditionality of beneficial outcomes for the tree, the mean effect of ants on the F. sur population studied was to increase pollinator production by up to nearly 20%. This study is among the few to have demonstrated an overall benefit to a plant of having homopteran-tending ants present on it.
  • Full Text:
  • Date Issued: 1995

Some adaptations of myrmeleontid (Neuroptera) and rhagionid (Diptera) larvae to life in hot dry sand

  • Authors: Youthed, Gayle Jean
  • Date: 1974
  • Subjects: Ant lions Rhagionidae
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5818 , http://hdl.handle.net/10962/d1007228
  • Description: From Introduction: Larvae of the families Myrmeleontidae, Neuroptera, (ant-lions) and Rhagionidae, Diptera, (worm-lions) all live in hot dry sand. Many of the ant-lion larvae and all the worm-lion larvae, construct small conical pits in the sand which are used for the capture of prey (Haub, 1942; Youthed and Horan, 1969a). Those ant-lion larvae which do not construct pits lie in wait for their prey just below the surface of the sand.
  • Full Text:
  • Date Issued: 1974

Synthetic and bioactivity studies of antiplasmodial and antibacterial marine natural products

  • Authors: Young, Ryan Mark
  • Date: 2012
  • Subjects: Antibacterial agents Marine natural products Marine pharmacology Plasmodium falciparum Staphylococcus aureus Isocyanides Imidazoles
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4378 , http://hdl.handle.net/10962/d1005043
  • Description: This thesis is divided into two parts, assessing marine and synthetic compounds active firstly against Plasmodium falciparum (Chapter 3 and 4) and secondly active against methicillin resistant Staphylococcus aureus (MRSA, Chapter 5). In Chapter 3 the synthesis of nine new tricyclic podocarpanes (3.203-3.207 and 3.209-3.212) from the diterpene (+)-manool is described. Initial SAR study of synthetic podocarpanes concluded that the most active compound was a C-13 phenyl substituted podocarpane (3.204, IC₅₀ 6.6 μM). By preparing analogues with varying halogenated substituents on the phenyl ring (3.209-3.212) the antiplasmodial activity was improved (IC₅₀ 1.4 μM), while simultaneously decreasing the haemolysis previously reported for this class of compounds. Inspired by the antiplasmodial activity of Wright and Wattanapiromsakul’s tricycle marine isonitriles (2.16-2.21 and 2.24-2.27) an unsuccessfully attempt was made to convert tertiary alcohol moieties to isonitrile functionalities in compounds 3.188, 3.204-3.207 and 3.209-3.212. Over a decade ago Wright et al. proposed a putative antiplasmodial mechanism of action for marine isonitriles (2.4, 2.9, 2.15, 2.19 and 2.35) and isothiocyanate (2.34) which involved interference in haem detoxification by P. falciparum thus inhibiting the growth of the parasite. In Chapter 4 we describe how we successfully managed to scale down Egan’s β-haematin inhibition assay for the analyses of small quantities of marine natural products as potential β-haematin inhibitors. Our modified assay revealed that the most active antiplasmodial marine isonitrile 2.9 (IC₅₀ 13 nM) showed total β-haematin inhibition while 2.15 (IC₅₀ 81 nM) and 2.19 (IC₅₀ 31 nM) showed partial inhibition at three equivalents relative to haem. Using contempary molecular modelling techniques the charge on the isonitrile functionality was more accurately describe and the modified charge data sets was used to explore docking of marine isonitriles to haem using AutoDock. In Chapter 5 we describe how a lead South African marine bisindole MRSA pyruvate kinase inhibitor (5.8) was discovered in collaboration with colleagues at the University of British Columbia (UBC) and how this discovery inspired us to design a synthetic route to the dibrominated bisindole, isobromotopsentin (5.20) in an attempt to increase the bioactivity displayed by 5.8. We devised a fast and high yielding synthetic route using microwave assited organic synthesis. We first tested this synthesis using simple aryl glyoxals (5.27-5.32) as precursors to synthesize biphenylimidazoles (5.21-5.26), which later allowed us to synthesize the ascidian natural product 5.111. This method was sucessfully extended to the synthesis of deoxytopsentin (5.33) from an N-Boc protected indole methyl ketone (5.89). We subsequently were able to effectively remove the carbamate protection via thermal decomposition by heating the protected bisindole imidazole (5.90) in a microwave reactor for 5 min under argon. The synthesis of 5.20 resulted in an inseparable mixture of monoprotected and totally deprotected topsentin products, and due to time constraints we were not able to optimise this synthesis. Nonetheless our synthesis of the marine natural product 5.33 which was faster and higher yielding than previously reported routes could be extended to the synthesis of other topsentin bisindoles (5.138-5.140). Work towards this goal continues in our laboratory.
  • Full Text:
  • Date Issued: 2012

Aspects of condition in captive and free-ranging dolphins

  • Authors: Young, Deborah Dione
  • Date: 1999
  • Subjects: Dolphins -- Physiology Dolphins -- Behavior
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5799 , http://hdl.handle.net/10962/d1006117
  • Description: Aspects of morphological and physiological condition of captive and net-caught dolphins were studied with respect to age, diet, reproduction and seasonal changes in environmental factors. These investigations aimed to provide base-line data on marine mammal physiological and morphological condition indices and to expand the knowledge of condition assessment of small cetaceans. By examining the interactive nature of animal condition and growth, diet and the environment, the study investigated the potential usefulness of animal condition indices to assess and monitor habitat quality. Base-line values for haematological and blood chemistry parameters were established for five captive bottlenose dolphins (Tursiops truncatus), using monthly blood samples, collected between 1992 and 1995, and corresponding measures of body weight and blubber thickness; feeding, dietary energy intake, water temperature and behavioural and medical records. Curves of best fit were used to interpret trends between leukocytic, haematological and blood chemistry parameters and morphology, diet and water temperature. WBC's and WBC differential cell types were related more distinctly to clinical changes in health, than to condition. RBC, HB and PCV were useful as short-term indicators of nutritional condition, with enhanced haematological status associated with greater food intake and improved diet quality. Weight was a more effective long-term indicator of nutritional status. The importance of blubber thickness measurements as a morphological index of condition was reinforced, with relationships between blubber thickness and haematology highlighting interactions between morphological and physiological condition. The complex interactions between haematology, diet, temperature and weight emphasised the need to account for all influential factors when considering haematological condition. The blood chemistry parameters of serum creatinine, BUN, BUN:creatinine and serum albumin provided the best indication of nutritional condition and diet quality in captive dolphins. Creatinine and BUN:creatinine also reflected changes in morphological condition. Reduced ALP was associated with nutritional stress but was more effectively used as an indication of metabolism and growth activity. LDH and CPK were highly variable and fluctuated with changing activity levels, limiting their use as condition indices. Serum sodium was an important indication of diet quality and hydration status. Many of these parameters effectively illustrated that physiological condition is compromised outside of the thermoneutral zone of the species. Bottlenose and common (Delphinus delphis) dolphins, incidentally caught in shark nets, were used to investigate the condition of free-ranging dolphins. Blood samples, taken as soon as possible after capture from drowned animals, were used to analyse physiological parameters. Dissections provided morphological data. Age and dietary status were assessed using growth layer groups in teeth and stomach content analyses, respectively. Morphological measures of net-caught dolphins reflected important interactions with diet, water temperature and reproductive status. Weight, girth and blubber thickness were valuable indicators of condition, although blubber thickness and proportional blubber weight were the best indicators of nutritional status. Condition of net-caught dolphins was difficult to assess in terms of leukocytic and haematological parameters. Stress- and post-mortem-associated changes, and variable data, reduced the usefulness of some parameters. WBC counts reflected on immunological status and served to emphasise changes in health, which may lead to deterioration in condition. WBC's showed potential as indicators of habitat quality, in terms of parasite load and/or pollution. Interactions between RBC, HB, PCV, MCV and dietary, morphological and environmental factors proved valuable in the short-term. Several haematological parameters were related to morphological condition, with weight, girth and blubber thickness, showing potential as non-invasive predictors of haematological status. Relationships between haematology and water temperature implied that dolphins have physiological and environmental "zones of comfort", within which condition is optimised. LDH and CPK were elevated by capture stress and post-mortem changes. Serum sodium and plasma glucose were good indicators of short-term nutritional status, but were altered by stress, which reduced their usefulness as condition indicators. BUN, albumin, globulin, albumin:globulin, total cholesterol and triglycerides appeared to be little affected by these changes and are potentially valuable indicators of condition in net-caught and/or free-ranging dolphins, particularly with respect to nutritional condition, and associated changes in morphology. Although data were limited, these parameters show the greatest potential as physiological indicators of animal condition and environmental health. The limitations of this study are recognised, however, results highlight the feasibility of using net-caught specimens to monitor the condition of free-ranging marine mammals, and the marine habitat as a whole. Relationships established in this study will be used to elucidate further on the interactive nature of marine mammal condition and aid in the development of a non-invasive condition assessment technique.
  • Full Text:
  • Date Issued: 1999

The philanthropic priorities of Chinese and Japanese Americans as they relate to Asian American culturally specific museums

  • Authors: Yok, Larry Tom
  • Date: 2016
  • Subjects: Museums -- Economic aspects -- United States Chinese Americans -- Development -- United States Non-governmental organizations -- Museums -- Economic aspects
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/13160 , vital:27157
  • Description: Asian American culturally specific museums began forming in the United States in 1963. There are now 11 in existence. Four of these museums (two Chinese American, one Japanese American and one Pan Asian American) dramatically expanded their programs and constructed large new facilities. These culturally specific museums are private nonprofit organizations that are reliant on private donors for most of their financial support. Asian Americans comprise the majority of these Asian American museums’ donor bases. Understanding why donors support these museums may be useful to the museums’ abilities to raise funds.In this thesis I explore the reasons Chinese and Japanese Americans support these culturally specific museums. I used data from my qualitative study involving in-depth interviews of 16 Chinese and Japanese American current and former donors to a Pan Asian culturally specific museum in Seattle, Washington along with interviews of chief executives and other key informants of five other culturally specific museums in addition to primary documents provided by the museums and related secondary information available through the Internet. I also conducted a literature review in the fields of Development Studies, racial and ethnic identity, museology, and philanthropy. While identifying the reasons donors support these culturally specific museums, I also identify the philanthropic priorities and criteria of Chinese and Japanese Americans residing in Seattle and compare them with similar studies of Asian American philanthropy conducted in other cities in the 1990’s. I also examine the roles played by these culturally specific museums in the promotion of social capital, cultural capital and heritage capital in their communities. Chinese and Japanese Americans support these museums to preserve and educate their communities about the contributions their forebears made to the development of the United States. Asian American history has been marginalized in conventional narratives and one mission of the Asian American culturally specific museums is to bring their stories into the American history mainstream. Creating and operating these museums requires substantial networking within the Chinese and Japanese American communities and with other ethnic communities to bring in visitors and obtain financial and other support. The museums promote social capital development through collaboration in the museums’ operations. They increase the communities’ cultural capital by assembling the dispersed cultural and heritage capital of the Chinese and Japanese American communities into curated collections. These Asian American culturally specific museums face challenges stemming from attrition in their donor bases due to age. The museums need to develop activities that attract new supporters who may be mixed race or mixed ethnicity or who are interested in social activism that impacts society. The museums also must create programs that are relevant to younger generations. The findings of this study lay the groundwork for further inquiry into the ways culturally specific museums promote bonding and bridging capital in low and middle class Asian American communities and the degree to which they affect development in their neighbourhoods. Further research into the museums’ educational programs efficacy as they relate to correcting misperceptions about Asian Americans among non-Asian Americans may be desirable.
  • Full Text:
  • Date Issued: 2016
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