List of Titles

Quick View

Composition and physiological roles of gut microbiota in the False Coding Moth (Thaumatotibia leucotreta)

- Richardson, Perryn Heather

Authors: Richardson, Perryn Heather
Date: 2023-10-13
Subjects: Uncatalogued
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/424457 , vital:72155
Description: Gut microbiota can have a profound influence on host performance, behaviour and fitness. For False Codling Moth (FCM), Thaumatotibia leucotreta (Lepidoptera: Tortricidae), a major pest of citrus in South Africa, little work has been undertaken to date on gut microbe diversity or its influence on the host. This thesis aimed to i) characterise the gut microbiome of FCM under laboratory conditions and in FCM from the field, ii) and produce moths with reduced gut microbiota through egg dechorionation, which was followed by iii) the measurement of a suite of physiological traits, namely mass, survival and thermal stress in FCM from normal laboratory, dechorionated laboratory and field collected larvae that may be indicative of overall field performance. We aimed to directly test the hypothesis that gut microbial diversity partly determines insect performance and fitness by measuring its effects on growth, development, and tolerance to cold temperatures in FCM. FCM eggs that underwent dechorionation with sodium hypochlorite had an overall effect on larval survival, egg morphology and both larval and adult moth physiological measures. Increasing concentrations of sodium hypochlorite significantly decreased insect survival, (𝜒2(1, n = 10 850) = 21.724, p-value < 0.0001), with a concentration of ≈3.69% as the concentration limit (p-value < 0.001). Successful dechorionation of FCM was achieved with a wash of sodium hypochlorite at around 3.69% concentration and was visually confirmed by reduction of FCM egg surface area, (𝜒2(25, n = 260) p-value < 0.0001) and Scanning Electron Micrographs of the egg morphology. The gut microbiome of FCM from the different focus treatments was successfully characterized. Identification of the dominant bacterial families in these microbiomes revealed Xanthobacteraceae, Beijerinckiaceae and Burkholderiaceae in both the laboratory reared and field collected larvae, which suggests their systematic association with T. leucotreta. The most abundant genera were revealed as Bradyrhizobium, Methylobacterium and Burkholderia-Caballeronia-Paraburkholderia. Comparison of larval mass showed that treatment (dechorionated or not) had a significant effect on larval mass (𝜒2(2, n = 230) = 22.703, p-value < 0.001), field larvae were heavier than both control larvae and larvae with a disrupted gut microbiome. However, adult insects with a disrupted gut microbiome had more mass than individuals from the control and field-collected larvae with intact gut microbiomes (𝜒2(2, n = 230) = 39.074, p-value < 0.001). Despite the difference in mass between larval treatments, there was no significant difference in relative protein (𝜒2(2, n = 24) = 5.680, p-value = 0.06), carbohydrate (𝜒2(2, n = 24) = 3.940, p-value = 0.14) or lipid (𝜒2(2, n = 24) = 6.032, p-value = 0.05) content between individuals from the control and dechorionated treatments and field-collected individuals. Turning to thermal physiology, insects collected from the field took significantly longer to recover from chill coma than both laboratory treatments with intact and disrupted gut microbiomes (𝜒2(2, n = 129 = 39.659, p-value < 0.001). In addition, exposure to cold stress showed that treatment had a significant effect on insect mortality (𝜒2(2, n = 272) = 9.176, p-value = 0.01), with individuals from the control and dechorionated treatment being less likely to die after experiencing cold stress compared to field-collected individuals. Differences in the mass and thermal tolerance of insects with intact and disrupted gut microbiota suggest that gut microbiota may play an important role in the cold performance of T. leucotreta, and these findings constitute the basis for future molecular work on the functions of these bacterial taxa. This research highlights the need for consideration of the effects of T. leucotreta microbiome in current pest control programs. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2023
Full Text:
Date Issued: 2023-10-13

Quick View

Composition portfolio

- Moss, Keith

Authors: Moss, Keith
Date: 2007
Subjects: Uncatalogued
Language: English
Type: Master's theses , text
Identifier: http://hdl.handle.net/10962/193724 , vital:45390
Description: Whitacre's music is primarily diatonic with subtle modulations, where the new key is always preserved diatonicaliy as well. I refer to this style as expanded diatonicism. Examples in my work of expanded diatonicism within this portfolio are to be found in navem ad somnium, Wynken, Blynken and Nod, as well as Hymn for Brass. My applications of expanded diatonic practices within each of these works are discussed in a separate appendix within the body of this portfolio. That these works are vocal or have a vocal inspiration (Hymn for Brass) reveals the extent of my initial reaction to Whitacre's music during a choral rehearsal. Furthermore, in my vocal compositions especially I chose texts which frequently gravitate towards ideas related to water, the ocean and ships. Whilst water has a soothing and inspiring influence upon me, presumably evidenced in my expanded diatonicism, it also represents my journey and investigation into the sound work of Whitacre in particular. It may be noticed that many of my works in this portfolio have religious orientated themes. I am a Christian, and belong to a Berean 2 Congregational Church. Whilst I am not Catholic or Anglican, I nonetheless have made use of texts from the liturgy of these denominations, as they emphasise the basis of my Christian faith. Why I chose Hymn for Brass as a title could possibly be construed as a religious reference, however it was named after the piece was written, and had no theological connotations in its inception save for the hymnody style of the orchestration. Providence and The Eventide both have a Christian philosophical foundation which is explored in depth in the accompanying appendix. The latter work explores an extension of my expanded diatonic style through incorporating aspects of chromaticism. The rationale for this is dealt with in my discussion of this work. This portfolio represents an overview of my compositional activities to date and displays my growing confidence with the technical aspects of composition as well as my yearning for experimentation with new ideas and manners of expression. , Thesis (MMus) -- Faculty of Humanities, Music and Musicology, 2007
Full Text:
Date Issued: 2007

Quick View

Construction Unions Negotiators Conference

- Building & Wood Workers International (BWI)

Authors: Building & Wood Workers International (BWI)
Date: 2009-05
Subjects: Uncatalogued
Language: English
Type: text
Identifier: http://hdl.handle.net/10962/105819 , vital:32572
Description: This publication aims to familiarise negotiators with inflation statistics, which are not as straight forward as they might seem at first glance. It provides negotiators with the latest inflation figures (at the time of publication), and puts forward a few guidelines for dealing with inflation in the context of collective bargaining. After ail, if you know what the rules of the game are you can break them property , here put any information that you think is important but there is no field for it, if there isnt remove the field
Full Text:
Date Issued: 2009-05

Quick View

Constructions of Ukuyalwa and marriage satisfaction: experiences of Xhosa couples in the Eastern Cape

- Bikwe, Siphuxolo

Authors: Bikwe, Siphuxolo
Date: 2023-03-30
Subjects: Uncatalogued
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/408805 , vital:70527
Description: Marital satisfaction may be described as the extent to which one’s expectations, desires and needs are being satisfied in their marriage. Studies that concern marital satisfaction provide us with crucial insights into factors that support or compromise the longevity of long-term, committed relationships. Little work has been done in understanding the role of cultural practices in marital satisfaction particularly in Africa, and South Africa more specifically. Ukuyalwa is a Xhosa ritual that takes place during a Xhosa traditional wedding, whereby the bride is introduced to the (traditional) guiding practices of her new home by the women of the family together with her sisters-in-law. This study informs the practice of African psychology as formulated by Ratele (2017b).Critical African psychology as a framework recognizes the construction of culture alongside political, socioeconomic, and historical matrices. These are acknowledged as an important element in psychological theories, methods, and explanations. This research project aimed to identify the discourses that circulate around ukuyalwa as a Xhosa cultural practice and consider the implications for the marital satisfaction of amaXhosa couples. The study interviewed 3 Xhosa couples of varying ages who had been married for different durations to develop an understanding of their experiences of ukuyalwa and marital satisfaction. Data was analyzed using a Foucauldian Discourse Analysis (FDA) which allowed for the identifications of the discourses that the couples used to construct ukuyalwa and marital satisfaction. The couples discursively constructed marriage as ‘divine unity’, ‘unification of families’ and ‘partnership’. Ukuyalwa was constructed as a ‘gendered process’, ideas of tradition and modernity, and a ‘foundation’ also became apparent. Satisfaction was constructed as ‘open communication’ and ‘work’. The couples’ positions shifted in their conversations, where in some instances they were 'learners’, ‘initiates’, and/or ‘passive’, and in other instances, they were ‘in charge’, ‘knowledgeable’, and ‘experts’. The discourses of culture, religion, and partnership circulated prominently in relation to marriage, ukuyalwa, and marital satisfaction. The findings of the study speak to how the couples’ constructions of marriage and cultural customs such as ukuyalwa are valuable as they often inform how couples behave in their marriage relationships and what they regard as satisfactory to them when it comes to marriage. These insights into what informs the couples’ ideas on marriage and satisfaction can be utilised in informing couples therapy interventions. , Thesis (MA) -- Faculty of Humanities, Psychology, 2023
Full Text:
Date Issued: 2023-03-30

Quick View

Consultative Conference on Education and Training, Cape Town 19-21 June 1996: workbook and discussion documents

- Food and Allied Workers' Union

Authors: Food and Allied Workers' Union
Date: 1996-06-19
Subjects: Uncatalogued
Language: English
Type: text , pamphlet
Identifier: http://hdl.handle.net/10962/105917 , vital:32583
Description: Ladies and Gentleman, the Honorable Minister and fellow working comrades, I take this opportunity of welcoming all of you to this Consultative Conference on Education, Training and Development. Many of you have travelled from far, having left many responsibilities behind to attend to this issue of ETD for workers and industry. I wish to immediately thank you for this sacrifice made, the dividends of which I believe will be reaped for a very long time yet. But what does ETD mean for workers and industry? Let me venture an opinion. I think at my age I am occasionally allowed the liberty to issue opinion. We think for workers and we speak as workers, ETD means an opportunity to break free from the shackles "of low skilled -low paid -low satisfaction jobs - jobs which provide neither security, preferment nor progression- jobs that neither builds the economy nor their families and communities. As a worker I know of these frustrations - as a trade unionist I have committed myself to overcoming these deprivations. For industry, ETD, I think has come to mean as much for employers as for workers - in numerous discussions FAWU has had with employers we have come to understand the close linkages employers are drawing between Education, training and development (ETD) and increased productivity. We all know that increased productivity means improved performance and improved performance strengthens a company's ability to survive and grow. And a company that stabilises or grows can only add value to the economy and all its peoples' lives. Thus the presence of employers here tonight seems to affirm this common belief in ETD.
Full Text:
Date Issued: 1996-06-19

Quick View

Controls of lateral and vertical variations in the geochemistry of the Hotazel Fe-Mn Formation at Nchwaning and Gloria mines, Kalahari Manganese Field, South Africa

- Dorbor Jr., Stephen Baysah

Authors: Dorbor Jr., Stephen Baysah
Date: 2023-10-13
Subjects: Uncatalogued
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/424621 , vital:72169
Description: The Paleoproterozoic Kalahari manganese field (KMF) in the Northern Cape Province, South Africa, hosts a large resource of manganese ores that has been of great interest over many decades. The Kalahari Manganese deposit (KMD), which is the largest of five erosional relics of the Hotazel Formation in the KMF, hosts three beds of Mn ores with alternating layers of banded iron formation (BIF) and hematite lutite. These three rock types are all evaluated for their mineralogy and geochemistry in this study, with emphasis on lateral and vertical distributions across the Gloria and Nchwaning Mines in the northernmost KMF, an area of high-grade, hydrothermally altered Mn mineralisation. The Mn ores of the Hotazel formation are traditionally categorised into two types. The carbonate-rich low Mn grade (Mn≤40 wt. %) ores (Mamatwan-type) domninates the largest part of the KMD, while carbonate-free, high Mn grade (Mn≥ 45 wt.%) ore (Wessels-type) occurs in the northernmost KMD. The Wessels-type ores are considered as the hydrothermally altered product of Mamatwan-type ores, and as indicated above, are the focus of this study. Five drill cores containing Wessels-type ores from the Nchwaning and Gloria area of the northern KMD were analysed to help understand the petrographic and particularly the geochemical variations in the Hotazel Fe-Mn Formation, both laterally for a given Mn layer of the three, and vertically across Mn layers as captured in specific drillcores. Petrographic and whole-rock geochemical results obtained from the three rock types of the Hotazel Formation show variations in their mineralogical and geochemical compositions, especially in the high-grade Mn ores themselves. Most of the samples of the BIFs layers are dominated by hematite and chert occurring in banded fashion, which is typical of a normal carbonate-free altered BIF discussed in this thesis. The BIFs can also be locally enriched in hematite (ferruginised), occurring as massive hematite ores usually at the top of the stratigraphic profiles. The presence of aegirine-rich assemblages is also noted occurring in some of the BIF and hematite lutite sections immediately above and below the Mn ore beds. The high-grade Mn ore beds vary greatly in mineralogy and texture of the ores laterally and even within a single drill core. In an extreme case, a single drillcore sampled from the Gloria mine (GL57) contains high-grade Wessels-type ore in the upper Mn bed and low-grade, Mamatwan-type ore in the lower Mn layer. Geochemically, the Mn ore bodies also show substantial geochemical variability, although a net increase in the Mn grade downward is usually characterised by a corresponding depletion in mainly bulk Ca, Si and carbonate. However, the Fe content appears to be consistently higher in the upper ore bodies of the drillcores than the lower ones, and the increase in the concentration of the Fe-oxide expectedly causes a relative decrease in the bulk Mn-oxide concentration, usually expressed as an antithetic relationship between the two elements. In terms of trace element distributions, this appears to be more significant in the Mn ores than the other two rock types affected by the same alteration process, probably due to the presence of Mn phases such as hausmannite and braunite serving as good hosts to several trace elements. Cu, Zn, Pb and to a lesser extent Mo are trace metals that appear to show elevated concentration levels (net enrichments) in high-grade Mn ore by comparison to the presumed Mamatwan-type protolith. Ba is an additional element of clear enrichment, manifested mainly as the mineral barite. The Northern KMD has a complex post-depositional history, which includes the intrusion of NE-SW-trending dykes, formation of the Mapedi/Gamagara erosional unconformity, normal faulting associated with the Wessels event and major thrust faults in the western part of the northern KMD. These structural events all have the potential to have contributed to the alteration and subsequent enrichment of the Mn ores in the Nchwaning and Gloria area. As such, the mineralogical, textural, and geochemical variations observed here can tentatively be attributed to the different structural features in the northern KMD. Classic interpretations suggest that normal N-S-trending fault structures have acted as fluid conduits for hydrothermal fluids, which led to the metasomatic alteration of the Mn ore body laterally. Drill cores proximal to and evidently affected by fault-controlled alteration in the SE and SW-portions of the Nchwaning area, have comparable mineralogical and geochemical characteristics for both ore bodies (upper and lower) with subdued alteration effects from the unconformed contact above. Fluids associated with the Mapedi/Gamagara unconformity, would have percolated down-stratigraphy causing oxidative ferruginisation, which led to the formation of massive hematite ores in the top BIF layers and ferruginised Mn ores in the Mn ore beds. This alteration effect appears more prominent in a drill core from the northern part of the study area where the unconformity contact appears more proximal to the upper Mn bed. Drill cores located in the western part of the Nchwaning area seem to also capture evidence of fluid alteration with enrichment in Na recorded in the local abundance of the mineral aegirine. Finally, the dyke structures appear to have acted as impermeable fluid barriers to both lateral and possibly down-dip fluid-flow. , Thesis (MSc) -- Faculty of Science, Geology, 2023
Full Text:
Date Issued: 2023-10-13

Quick View

Crop fields abandonment: assessing the dynamics of degradation in relation to leverage points for sustainable land management in the Macubeni catchment, South Africa

- Sibiya, Silindile

Authors: Sibiya, Silindile
Date: 2023-03-29
Subjects: Uncatalogued
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/422470 , vital:71945
Description: Soil erosion is a major global environmental problem and a pervasive forms of land degradation that threatens land productivity and food and water security. Some of the biggest sources of sediment in catchments are previously cultivated lands. Regardless of this factor, the abandonment of cultivated fields is not well-researched. Sustainable land management (SLM) interventions can play a significant role in mitigating and halting land degradation. This study investigated the dynamics of degradation exhibited by crop fields and the potential impacts of SLM interventions, using a leverage points framework and a case study in the Macubeni catchment of South Africa. The research answers three questions: (1) What is the relationship between the usage status of crop fields and degradation in Macubeni? (2) What are the drivers of crop field abandonment and how do they interact in the system? (3) Can proposed sustainable land management interventions tackle the dynamics of land abandonment, and associated degradation, at the root cause level? An empirical-analytical approach using a four step multi-method process was followed, in which crop fields were mapped using ArcGIS tools, literature was reviewed alongside stakeholder engagements, qualitative systems mapping modelling was undertaken, and a Multi-Criteria Analysis (MCA) with leverage points hierarchy was used to integrate all the steps together. The results revealed that the various drivers of crop field abandonment include natural environmental factors, socio-economic and social factors. 47.41% of the total crop fields in Macubeni were classified as highly degraded, and abandoned fields covered 37.47%. The statistical Chi-Square Test also confirmed that there is a significant relationship between the usage status and degradation level in crop fields. The SLM interventions assessed in the study have the potential to tackle the dynamics of land abandonment at a root cause level, however, there is a need to first shift the community’s mental models to address the existing sources of change resistance that are hindering successful implementation. Furthermore, the innovative multi-method approach applied in this study can further provide a holistic, dynamic, and integrated decision-support to land conservation and rehabilitation projects in similar settings across South Africa and other developing countries as opposed to the more traditional one-dimensional approaches. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2023
Full Text:
Date Issued: 2023-03-29

Showing items 101 - 120 of 635