Left-invariant optimal control problems of the Engel group: classification, stability, and integration
- Authors: McLean, Catherine Eve
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62949 , vital:28323 , http://doi.org/10.21504/10962/62949
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
- Authors: McLean, Catherine Eve
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62949 , vital:28323 , http://doi.org/10.21504/10962/62949
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
Long-term analysis of ionospheric response during geomagnetic storms in mid, low and equatorial latitudes
- Matamba, Tshimangadzo Merline
- Authors: Matamba, Tshimangadzo Merline
- Date: 2018
- Subjects: Ionospheric storms , Coronal mass ejections , Corotating interaction regions , Solar flares , Global Positioning System , Ionospheric critical frequencies , Equatorial Ionization Anomaly (EIA)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63991 , vital:28517
- Description: Understanding changes in the ionosphere is important for High Frequency (HF) communications and navigation systems. Ionospheric storms are the disturbances in the Earth’s upper atmosphere due to solar activities such as Coronal Mass Ejections (CMEs), Corotating interaction Regions (CIRs) and solar flares. This thesis reports for the first time on an investigation of ionospheric response to great geomagnetic storms (Disturbance storm time, Dst ≤ −350 nT) that occurred during solar cycle 23. The storm periods analysed were 29 March - 02 April 2001, 27 - 31 October 2003, 18 - 23 November 2003 and 06 - 11 November 2004. Global Navigation Satellite System (GNSS), Total Electron Content (TEC) and ionosonde critical frequency of F2 layer (foF2) data over northern hemisphere (European sector) and southern hemisphere (African sector) mid-latitudes were used to study the ionospheric responses within 15E° - 40°E longitude and ±31°- ±46° geomagnetic latitude. Mid-latitude regions within the same longitude sector in both hemispheres were selected in order to assess the contribution of the low latitude changes especially the expansion of Equatorial Ionization Anomaly (EIA) also known as the dayside ionospheric super-fountain effect during these storms. In all storm periods, both negative and positive ionospheric responses were observed in both hemispheres. Negative ionospheric responses were mainly due to changes in neutral composition, while the expansion of the EIA led to pronounced positive ionospheric storm effect at mid-latitudes for some storm periods. In other cases (e.g 29 October 2003), Prompt Penetration Electric Fields (PPEF), EIA expansion and large scale Traveling Ionospheric Disturbances (TIDs) were found to be present during the positive storm effect at mid-latitudes in both hemispheres. An increase in TEC on the 28 October 2003 was because of the large solar flare with previously determined intensity of X45± 5. A further report on statistical analysis of ionospheric storm effects due to Corotating Interaction Region (CIR)- and Coronal Mass Ejection (CME)-driven storms was performed. The storm periods analyzed occurred during the period 2001 - 2015 which covers part of solar cycles 23 and 24. Dst≤ -30 nT and Kp≥ 3 indices were used to identify the storm periods considered. Ionospheric TEC derived from IGS stations that lie within 30°E - 40°E geographic longitude in mid, low and equatorial latitude over the African sector were used. The statistical analysis of ionospheric storm effects were compared over mid, low and equatorial latitudes in the African sector for the first time. Positive ionospheric storm effects were more prevalent during CME-driven and CIR-driven over all stations considered in this study. Negative ionospheric storm effects occurred only during CME-driven storms over mid-latitude stations and were more prevalent in summer. The other interesting finding is that for the stations considered over mid-, low, and equatorial latitudes, negative-positive ionospheric responses were only observed over low and equatorial latitudes. A significant number of cases where the electron density changes remained within the background variability during storm conditions were observed over the low latitude stations compared to other latitude regions.
- Full Text:
- Date Issued: 2018
- Authors: Matamba, Tshimangadzo Merline
- Date: 2018
- Subjects: Ionospheric storms , Coronal mass ejections , Corotating interaction regions , Solar flares , Global Positioning System , Ionospheric critical frequencies , Equatorial Ionization Anomaly (EIA)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63991 , vital:28517
- Description: Understanding changes in the ionosphere is important for High Frequency (HF) communications and navigation systems. Ionospheric storms are the disturbances in the Earth’s upper atmosphere due to solar activities such as Coronal Mass Ejections (CMEs), Corotating interaction Regions (CIRs) and solar flares. This thesis reports for the first time on an investigation of ionospheric response to great geomagnetic storms (Disturbance storm time, Dst ≤ −350 nT) that occurred during solar cycle 23. The storm periods analysed were 29 March - 02 April 2001, 27 - 31 October 2003, 18 - 23 November 2003 and 06 - 11 November 2004. Global Navigation Satellite System (GNSS), Total Electron Content (TEC) and ionosonde critical frequency of F2 layer (foF2) data over northern hemisphere (European sector) and southern hemisphere (African sector) mid-latitudes were used to study the ionospheric responses within 15E° - 40°E longitude and ±31°- ±46° geomagnetic latitude. Mid-latitude regions within the same longitude sector in both hemispheres were selected in order to assess the contribution of the low latitude changes especially the expansion of Equatorial Ionization Anomaly (EIA) also known as the dayside ionospheric super-fountain effect during these storms. In all storm periods, both negative and positive ionospheric responses were observed in both hemispheres. Negative ionospheric responses were mainly due to changes in neutral composition, while the expansion of the EIA led to pronounced positive ionospheric storm effect at mid-latitudes for some storm periods. In other cases (e.g 29 October 2003), Prompt Penetration Electric Fields (PPEF), EIA expansion and large scale Traveling Ionospheric Disturbances (TIDs) were found to be present during the positive storm effect at mid-latitudes in both hemispheres. An increase in TEC on the 28 October 2003 was because of the large solar flare with previously determined intensity of X45± 5. A further report on statistical analysis of ionospheric storm effects due to Corotating Interaction Region (CIR)- and Coronal Mass Ejection (CME)-driven storms was performed. The storm periods analyzed occurred during the period 2001 - 2015 which covers part of solar cycles 23 and 24. Dst≤ -30 nT and Kp≥ 3 indices were used to identify the storm periods considered. Ionospheric TEC derived from IGS stations that lie within 30°E - 40°E geographic longitude in mid, low and equatorial latitude over the African sector were used. The statistical analysis of ionospheric storm effects were compared over mid, low and equatorial latitudes in the African sector for the first time. Positive ionospheric storm effects were more prevalent during CME-driven and CIR-driven over all stations considered in this study. Negative ionospheric storm effects occurred only during CME-driven storms over mid-latitude stations and were more prevalent in summer. The other interesting finding is that for the stations considered over mid-, low, and equatorial latitudes, negative-positive ionospheric responses were only observed over low and equatorial latitudes. A significant number of cases where the electron density changes remained within the background variability during storm conditions were observed over the low latitude stations compared to other latitude regions.
- Full Text:
- Date Issued: 2018
Mannich base metal complexes and their thiocyanate analogues as catalysts in the oxidation of Catechol
- Authors: Ayeni, Ayowole Olaolu
- Date: 2018
- Subjects: Mannich bases , Catechol , Catechol -- Oxidation , Thiocyanates , Catalysts
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62339 , vital:28156
- Description: The study focused on the design of new Cu(II) and Fe(III) complexes, with or without thiocyanate (NCS-), as possible candidates of catechol oxidation using 3,5-di-tert-butyl catechol (3,5-DTBC) as substrate. Two classes of Mannich bases were studied depending on the active methylene group from which they were formed, being either p-cresol or acetaminophen. The ligands were characterised by 1H and 13C NMR spectroscopy. Crystal structures of three of the ligands are newly reported, along with detailed discussion of polymorphism observed in one of the ligands, and the nature of the hydrogen within the ligands in the solid state as well as in solution. The Mannich bases behaved as bidentate (NO), tridentate (NNO) and tetradentate (NNOO) ligands on coordination to Cu(II) and Fe(III) ions in which the hydroxyl group may be protonated or deprotonated. Coordination was determined by IR spectroscopy, investigating shifts in vOH, vC-O and in vCNC of the Mannich bases. The vCNC stretching frequencies v1 and v2 of asymmetrical piperazine Mannich bases were observed to shift upward in few cases upon complexation and this is attributed to (chair-boat) conformational change. The mode of coordination of the thiocyanate was determined by IR spectroscopy. Of the forty metal complexes investigated, six groups of metal complexes were identified as follows: (i) Ma(Ln)aClb-cH2O; (ii) Ma(HLn)a(NCS)aClb; (iii) Ma(Ln)a(NCS)aClb; (iv) Ma(HLn)aClb-cH2O; (v) Ma(Ln)a(NCS)a-cH2O; (vi) Ma(HLn)a(NCS)a-cH2O where a = 1 - 2 ; b = 1 - 4, c = 1 - 8. Molar conductivity values of 4.38 - 161.77 Q-1.cm2.mol-1 for the Cu(II) and Fe(III) complexes in DMSO showed that they range from non-electrolytes to 1:1 and 1:2 electrolytes. Electronic spectra for the ligands and the complexes were conducted in DMF and DMSO. The ligands are characterised by and n→n* and n→n* transitions. Intraligand charge transfer transitions peculiar to the nitro group were observed at about 430 nm for the nitro containing ligands. On coordination, these bands overshadowed the d-d transitions particularly for the nitro-Mannich bases. On complexation, ligand to metal charge transfer transitions associated with the hydroxyl were observed between 320 - 420 nm. Charge transfer transitions associated with the thiocyanates were also observed and discussed. The d-d transitions for high spin Fe(III) complexes are spin forbidden and generally uninformative. Those of Cu(II) are spin allowed and allow tentative structural proposals. Square planar and octahedral geometry are generally prevalent in the Cu(II) complexes with trigonal bipyramidal observed in few instances. The Fe(III) complexes are generally octahedral. Thirty-nine of the forty synthesised Cu(II) and Fe(III) complexes were catalytically active on the substrate (3,5-DTBC) in DMF with turnover rates (kcat) reported in the range of 1.86 ± 0.09 to 112.32 ± 3.72 h-1. From this pool of complexes, sixteen isostructural pairs were identified in terms of geometry, molecular formula and the source of the Mannich base and the following conclusions were made: The presence of thiocyanate in the metal complexes reduce catecholase activity; the Cu(II) complexes generally have better activity but the Fe(III) complexes become more relatively active with highly electron donating groups while the Cu(II) complexes become less; dinuclear complexes have greater activity than the mononuclear.
- Full Text:
- Date Issued: 2018
- Authors: Ayeni, Ayowole Olaolu
- Date: 2018
- Subjects: Mannich bases , Catechol , Catechol -- Oxidation , Thiocyanates , Catalysts
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62339 , vital:28156
- Description: The study focused on the design of new Cu(II) and Fe(III) complexes, with or without thiocyanate (NCS-), as possible candidates of catechol oxidation using 3,5-di-tert-butyl catechol (3,5-DTBC) as substrate. Two classes of Mannich bases were studied depending on the active methylene group from which they were formed, being either p-cresol or acetaminophen. The ligands were characterised by 1H and 13C NMR spectroscopy. Crystal structures of three of the ligands are newly reported, along with detailed discussion of polymorphism observed in one of the ligands, and the nature of the hydrogen within the ligands in the solid state as well as in solution. The Mannich bases behaved as bidentate (NO), tridentate (NNO) and tetradentate (NNOO) ligands on coordination to Cu(II) and Fe(III) ions in which the hydroxyl group may be protonated or deprotonated. Coordination was determined by IR spectroscopy, investigating shifts in vOH, vC-O and in vCNC of the Mannich bases. The vCNC stretching frequencies v1 and v2 of asymmetrical piperazine Mannich bases were observed to shift upward in few cases upon complexation and this is attributed to (chair-boat) conformational change. The mode of coordination of the thiocyanate was determined by IR spectroscopy. Of the forty metal complexes investigated, six groups of metal complexes were identified as follows: (i) Ma(Ln)aClb-cH2O; (ii) Ma(HLn)a(NCS)aClb; (iii) Ma(Ln)a(NCS)aClb; (iv) Ma(HLn)aClb-cH2O; (v) Ma(Ln)a(NCS)a-cH2O; (vi) Ma(HLn)a(NCS)a-cH2O where a = 1 - 2 ; b = 1 - 4, c = 1 - 8. Molar conductivity values of 4.38 - 161.77 Q-1.cm2.mol-1 for the Cu(II) and Fe(III) complexes in DMSO showed that they range from non-electrolytes to 1:1 and 1:2 electrolytes. Electronic spectra for the ligands and the complexes were conducted in DMF and DMSO. The ligands are characterised by and n→n* and n→n* transitions. Intraligand charge transfer transitions peculiar to the nitro group were observed at about 430 nm for the nitro containing ligands. On coordination, these bands overshadowed the d-d transitions particularly for the nitro-Mannich bases. On complexation, ligand to metal charge transfer transitions associated with the hydroxyl were observed between 320 - 420 nm. Charge transfer transitions associated with the thiocyanates were also observed and discussed. The d-d transitions for high spin Fe(III) complexes are spin forbidden and generally uninformative. Those of Cu(II) are spin allowed and allow tentative structural proposals. Square planar and octahedral geometry are generally prevalent in the Cu(II) complexes with trigonal bipyramidal observed in few instances. The Fe(III) complexes are generally octahedral. Thirty-nine of the forty synthesised Cu(II) and Fe(III) complexes were catalytically active on the substrate (3,5-DTBC) in DMF with turnover rates (kcat) reported in the range of 1.86 ± 0.09 to 112.32 ± 3.72 h-1. From this pool of complexes, sixteen isostructural pairs were identified in terms of geometry, molecular formula and the source of the Mannich base and the following conclusions were made: The presence of thiocyanate in the metal complexes reduce catecholase activity; the Cu(II) complexes generally have better activity but the Fe(III) complexes become more relatively active with highly electron donating groups while the Cu(II) complexes become less; dinuclear complexes have greater activity than the mononuclear.
- Full Text:
- Date Issued: 2018
Modelling Ionospheric vertical drifts over the African low latitude region
- Dubazane, Makhosonke Berthwell
- Authors: Dubazane, Makhosonke Berthwell
- Date: 2018
- Subjects: Ionospheric drift , Magnetometers , Functions, Orthogonal , Neural networks (Computer science) , Ionospheric electron density -- Africa , Communication and Navigation Outage Forecasting Systems (C/NOFS)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63356 , vital:28396
- Description: Low/equatorial latitudes vertical plasma drifts and electric fields govern the formation and changes of ionospheric density structures which affect space-based systems such as communications, navigation and positioning. Dynamical and electrodynamical processes play important roles in plasma distribution at different altitudes. Because of the high variability of E × B drift in low latitude regions, coupled with various processes that sometimes originate from high latitudes especially during geomagnetic storm conditions, it is challenging to develop accurate vertical drift models. This is despite the fact that there are very few instruments dedicated to provide electric field and hence E × B drift data in low/equatorial latitude regions. To this effect, there exists no ground-based instrument for direct measurements of E×B drift data in the African sector. This study presents the first time investigation aimed at modelling the long-term variability of low latitude vertical E × B drift over the African sector using a combination of Communication and Navigation Outage Forecasting Systems (C/NOFS) and ground-based magnetometer observations/measurements during 2008-2013. Because the approach is based on the estimation of equatorial electrojet from ground-based magnetometer observations, the developed models are only valid for local daytime. Three modelling techniques have been considered. The application of Empirical Orthogonal Functions and partial least squares has been performed on vertical E × B drift modelling for the first time. The artificial neural networks that have the advantage of learning underlying changes between a set of inputs and known output were also used in vertical E × B drift modelling. Due to lack of E×B drift data over the African sector, the developed models were validated using satellite data and the climatological Scherliess-Fejer model incorporated within the International Reference Ionosphere model. Maximum correlation coefficient of ∼ 0.8 was achieved when validating the developed models with C/NOFS E × B drift observations that were not used in any model development. For most of the time, the climatological model overestimates the local daytime vertical E × B drift velocities. The methods and approach presented in this study provide a background for constructing vertical E ×B drift databases in longitude sectors that do not have radar instrumentation. This will in turn make it possible to study day-to-day variability of vertical E×B drift and hopefully lead to the development of regional and global models that will incorporate local time information in different longitude sectors.
- Full Text:
- Date Issued: 2018
- Authors: Dubazane, Makhosonke Berthwell
- Date: 2018
- Subjects: Ionospheric drift , Magnetometers , Functions, Orthogonal , Neural networks (Computer science) , Ionospheric electron density -- Africa , Communication and Navigation Outage Forecasting Systems (C/NOFS)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63356 , vital:28396
- Description: Low/equatorial latitudes vertical plasma drifts and electric fields govern the formation and changes of ionospheric density structures which affect space-based systems such as communications, navigation and positioning. Dynamical and electrodynamical processes play important roles in plasma distribution at different altitudes. Because of the high variability of E × B drift in low latitude regions, coupled with various processes that sometimes originate from high latitudes especially during geomagnetic storm conditions, it is challenging to develop accurate vertical drift models. This is despite the fact that there are very few instruments dedicated to provide electric field and hence E × B drift data in low/equatorial latitude regions. To this effect, there exists no ground-based instrument for direct measurements of E×B drift data in the African sector. This study presents the first time investigation aimed at modelling the long-term variability of low latitude vertical E × B drift over the African sector using a combination of Communication and Navigation Outage Forecasting Systems (C/NOFS) and ground-based magnetometer observations/measurements during 2008-2013. Because the approach is based on the estimation of equatorial electrojet from ground-based magnetometer observations, the developed models are only valid for local daytime. Three modelling techniques have been considered. The application of Empirical Orthogonal Functions and partial least squares has been performed on vertical E × B drift modelling for the first time. The artificial neural networks that have the advantage of learning underlying changes between a set of inputs and known output were also used in vertical E × B drift modelling. Due to lack of E×B drift data over the African sector, the developed models were validated using satellite data and the climatological Scherliess-Fejer model incorporated within the International Reference Ionosphere model. Maximum correlation coefficient of ∼ 0.8 was achieved when validating the developed models with C/NOFS E × B drift observations that were not used in any model development. For most of the time, the climatological model overestimates the local daytime vertical E × B drift velocities. The methods and approach presented in this study provide a background for constructing vertical E ×B drift databases in longitude sectors that do not have radar instrumentation. This will in turn make it possible to study day-to-day variability of vertical E×B drift and hopefully lead to the development of regional and global models that will incorporate local time information in different longitude sectors.
- Full Text:
- Date Issued: 2018
Modelling plant water use of the grassland and thicket biomes in the Eastern Cape, South Africa: towards an improved understanding of the impact of invasive alien plants on soil chemistry, biomass production and evapotranspiration
- Authors: Gwate, Onalenna
- Date: 2018
- Subjects: Grasslands -- South Africa -- Eastern Cape , Invasive plants -- South Africa -- Eastern Cape , Rangelands -- South Africa -- Eastern Cape , Range ecology-- South Africa -- Eastern Cape , Rangelands -- Water-supply , Rangelands -- Weed control , Evapotranspiration , Plant-water relationships
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54800 , vital:26617
- Description: It is imperative to understand the strong coupling between the carbon capture process and water use to sustainably manage rangelands. Woody encroachment is undermining rangelands grass production. Evapotranspiration (ET) highlights the links between ecosystem carbon capture process and water use. It forms the biggest flux of the hydrological cycle after precipitation yet it is not well understood. The Grassland and the Albany Thicket (AT) biomes in the Eastern Cape, South Africa, provide an interesting space to study the dynamics in rangelands biomass production and the associated water use. Therefore, the main purpose of this study was to contribute towards management of rangelands by understanding the dynamics in rangeland grass production and water use. To achieve this aim, the impact of Acacia mearnsii, an invasive alien plant, on soil chemical properties and rangelands grass production was investigated. This was achieved by analysing the biophysical attributes of A. mearnsii as they related to grass production. Secondly, selected soil variables that could be used as a prognosis for landscape recovery or deterioration were evaluated. In addition, aboveground grass biomass was measured in areas cleared of A. mearnsii and regression equations were prepared to help model aboveground grass biomass in areas cleared of A. mearnsi. The thesis also explored dynamics in water vapour and energy fluxes in these two biomes using an eddy covariance system. Consequently, water vapour and energy fluxes were evaluated in order to understand landscape water use and energy partitioning in the landscape. The study also tested the application of Penman-Monteith equation based algorithms for estimating ET with micrometeorological techniques used for validation. Pursuant to this, the Penman- Monteith-Leuning (PML) and Penman-Monteith-Palmer (PMP) equations were applied. In addition, some effort was devoted to improving the estimates of ET from the PMP by incorporating a direct soil evaporation component. Finally, the influence of local changes in catchment characteristics on ET was explored through the application of a variant of the Budyko framework and investigating dynamics in the evaporative index as well as applying tests for trends and shifts on ET and rainfall data to detect changes in mean quaternary catchment rainfall and ET. Results revealed that A. mearnsii affected soil chemical properties and impaired grass production in rangelands. Hence, thinning of canopies provided an optimal solution for enhanced landscape water use to sequestrate carbon, provide shade, grazing, and also wood fuel. It was also shown that across sites, ET was water limited since differences between reference ET and actual ET were large. ET was largely sensitive to vapour pressure deficit and surface conductance than to net radiation, indicating that the canopies were strongly coupled with the boundary layer. Rangeland ET was successfully simulated and evaporation from the soil was the dominant flux, hence there is scope for reducing the so-called ‘unproductive’ water use. Further, it was shown that the PML was better able to simulate ET compared to the PMP model as revealed by different model evaluation metrics such as the root mean square error, absolute mean square error and the root mean square observations standard deviation ratio. The incorporation of a soil evaporation component in the PMP model improved estimates of ET as revealed by the root mean square error. The results also indicated that both the catchment parameter (w) and the evaporative index were important in highlighting the impacts of land cover change on ET. It was also shown that, despite changes in the local environment such as catchment characteristics, global forces also affected ET at a local scale. Overall, the study demonstrated that combining remote sensing and ground based observations was important to better understand rangeland grass production and water use dynamics.
- Full Text:
- Date Issued: 2018
- Authors: Gwate, Onalenna
- Date: 2018
- Subjects: Grasslands -- South Africa -- Eastern Cape , Invasive plants -- South Africa -- Eastern Cape , Rangelands -- South Africa -- Eastern Cape , Range ecology-- South Africa -- Eastern Cape , Rangelands -- Water-supply , Rangelands -- Weed control , Evapotranspiration , Plant-water relationships
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54800 , vital:26617
- Description: It is imperative to understand the strong coupling between the carbon capture process and water use to sustainably manage rangelands. Woody encroachment is undermining rangelands grass production. Evapotranspiration (ET) highlights the links between ecosystem carbon capture process and water use. It forms the biggest flux of the hydrological cycle after precipitation yet it is not well understood. The Grassland and the Albany Thicket (AT) biomes in the Eastern Cape, South Africa, provide an interesting space to study the dynamics in rangelands biomass production and the associated water use. Therefore, the main purpose of this study was to contribute towards management of rangelands by understanding the dynamics in rangeland grass production and water use. To achieve this aim, the impact of Acacia mearnsii, an invasive alien plant, on soil chemical properties and rangelands grass production was investigated. This was achieved by analysing the biophysical attributes of A. mearnsii as they related to grass production. Secondly, selected soil variables that could be used as a prognosis for landscape recovery or deterioration were evaluated. In addition, aboveground grass biomass was measured in areas cleared of A. mearnsii and regression equations were prepared to help model aboveground grass biomass in areas cleared of A. mearnsi. The thesis also explored dynamics in water vapour and energy fluxes in these two biomes using an eddy covariance system. Consequently, water vapour and energy fluxes were evaluated in order to understand landscape water use and energy partitioning in the landscape. The study also tested the application of Penman-Monteith equation based algorithms for estimating ET with micrometeorological techniques used for validation. Pursuant to this, the Penman- Monteith-Leuning (PML) and Penman-Monteith-Palmer (PMP) equations were applied. In addition, some effort was devoted to improving the estimates of ET from the PMP by incorporating a direct soil evaporation component. Finally, the influence of local changes in catchment characteristics on ET was explored through the application of a variant of the Budyko framework and investigating dynamics in the evaporative index as well as applying tests for trends and shifts on ET and rainfall data to detect changes in mean quaternary catchment rainfall and ET. Results revealed that A. mearnsii affected soil chemical properties and impaired grass production in rangelands. Hence, thinning of canopies provided an optimal solution for enhanced landscape water use to sequestrate carbon, provide shade, grazing, and also wood fuel. It was also shown that across sites, ET was water limited since differences between reference ET and actual ET were large. ET was largely sensitive to vapour pressure deficit and surface conductance than to net radiation, indicating that the canopies were strongly coupled with the boundary layer. Rangeland ET was successfully simulated and evaporation from the soil was the dominant flux, hence there is scope for reducing the so-called ‘unproductive’ water use. Further, it was shown that the PML was better able to simulate ET compared to the PMP model as revealed by different model evaluation metrics such as the root mean square error, absolute mean square error and the root mean square observations standard deviation ratio. The incorporation of a soil evaporation component in the PMP model improved estimates of ET as revealed by the root mean square error. The results also indicated that both the catchment parameter (w) and the evaporative index were important in highlighting the impacts of land cover change on ET. It was also shown that, despite changes in the local environment such as catchment characteristics, global forces also affected ET at a local scale. Overall, the study demonstrated that combining remote sensing and ground based observations was important to better understand rangeland grass production and water use dynamics.
- Full Text:
- Date Issued: 2018
Movement of coastal fishery species in Southern Africa: research trends, characterisation of behaviours and a case study on fishery implications
- Authors: Maggs, Jade Quinton
- Date: 2018
- Subjects: Fishery management -- Africa, Southern , Fisheries -- Africa, Southern , Fisheries -- Catch effort , Fisheries -- Environmental aspects , Fisheries --Monitoring , Biotelemetry , Sustainable fisheries -- Africa, Southern , Overfishing -- Africa, Southern
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60574 , vital:27798
- Description: Movement of fishes is an integral part of their daily life, but has significant implications for fishery management. As with nearly all coastal countries, South Africa relies on coastal fisheries as a renewable resource, but many stocks have been overexploited for decades. Although it has long been recognised that an understanding of fish movement is necessary for effective management, it is with some difficulty that the subject has been studied in the past. In recent years, however, improvements in technology have provided the means for more in-depth investigations into fish movement. This research has revealed a range of complex movement behaviours. Movement in fishes occurs on a variety of temporal and spatial scales leading to the characteristic patterns of distribution and abundance observed in marine ecosystems. Fishes move nearly constantly in search of food, shelter or reproductive opportunities. Observations of behaviours such as long-term site fidelity, longdistance migration and natal homing are enabling ecologists to understand patterns of distribution and abundance within a species' range. Fish movement around the South African coast has been studied on numerous occasions but this has largely been confined to studies on single species. Movement behaviour of multiple species has been studied, but this has been limited to spatially localised marine protected area research. There has been little attempt in southern Africa to synthesize interspecific movement behaviour over wide spatial scales.Unprecedented concern over the biological effects of overexploitation, together with rapid technological advances in biotelemetry, have provided the impetus for much research, on a global scale, into the movement of marine animals. I reviewed 101 marine and estuarine fish movement studies from southern Africa, published from 1928 to 2014, with the aim of synthesising research trends and findings. Trends showed an increasing emphasis on fish movement research in publications in the sub-tropical and warm-temperate biogeographic regions along the south and east coasts of southern Africa. Although 63% of publications featured only marine studies, research into fine-scale habitat use in estuaries has been on the increase, concomitant with increasing accessibility of biotelemetry. Overall, 26 fish families were identified in the surveyed literature with regionally endemic sparids featuring in 32% of the publications. Ten movement themes were identified in the surveyed literature, including broad-scale movement patterns, which featured in 68% of studies, followed by fine- scale habitat usage (33%) and protected areas (26%). The most prominent phenomenon, emerging from this research, is that of partial migration, which describes the occurrence of resident and migratory behaviour within a coexisting animal population. Substantial progress has also been made in unravelling the complexities of fine-scale movements in marine reserves and habitat usage in estuaries. While this knowledge has enabled more effective management of South Africa's multi-user, multi-species fisheries, focus should now be directed at improving our understanding of the commonalities in movement behaviour, the associated driving forces behind this behaviour and the extent of movement across reserve boundaries. Mark-recapture data, collected over the past 30 years by the Oceanographic Research Institute’s Cooperative Fish Tagging Project (ORICFTP), were used to investigate broad- scale movement patterns of 30 prominent coastal fishery species (Chapter 4). Fishes were tagged with plastic dart tags along the coastline of southern Africa from Angola to Mozambique. This exercise yielded more than 10000 recaptures. The 30 chosen species represented 14 families, although 12 species belonged to a single family (Sparidae). Overall, 67% of recaptures were reported from the original tagging locality and 73% were recorded within 5 km of the tagging locality. The remaining observations extended from 6-3000 km. Movements were assigned to four distance bins (0-5 km, 6-50km, 51-500km and >500 km) and modelled with an ordinal logistic regression. Species, life-stage (juvenile/adult) and time- at-liberty were included as predictor variables. Model coefficients were then included in a cluster analysis, which produced two primary groupings of species (Category I and II), with two sub-groupings (Category IIa and IIb). Category I species were characterised by wide-ranging movements, greatest median recapture length and highest trophic levels. Category II species were characterised by residency, lower median recapture length and lower trophic levels. These findings have implications for fisheries management. Exploitation of resident species may lead to localised depletion, but their diffuse spatial distribution may offer some resilience. In contrast, even localised targeting of migratory species may pose a population level risk if individuals are known to aggregate. Life-cycle diversity or intra-population variability describes the existence of alternative strategies or tactics among coexisting individuals within an animal population (Chapter 5). Partial migration is a specific case of life-cycle diversity where coexisting groups exhibit either resident or migratory (wide-ranging) behaviour within a single population. Mark- recapture data collected under the auspices of the ORICFTP were used to investigate the occurrence and nature of life-cycle diversity in the movement behaviour of five non- diadromous fish species around the coastline of southern Africa. Among the five species were three teleosts (Category I and IIa) and two elasmobranchs (Category I). A fish was considered to have remained resident if recaptured within 0-5 km after 365 days at liberty. A fish was considered to have undertaken a wide-ranging movement if recaptured more than 50 km away from the release site in 365 days or less. A total of 1848 individuals from the five study species were recaptured during the study, of which 73% of the observations were classified as being resident. Binomial logistic regression confirmed that species, life-stage (juvenile/adult) and ecoregion were significant (p < 0.001) predictors of the probability of wide-ranging behaviour. A Gaussian model confirmed that species and ecoregion were also significant (p < 0.001) predictors of direction and distance of wide-ranging movement. However, the direction and distance of wide-ranging movements in juveniles did not differ significantly (p > 0.05) to that of adults. The median growth rate was mostly greater in wide- ranging individuals; however, this was only statistically significant (p < 0.05) in two cases. These findings provide unequivocal evidence of life-cycle diversity in five fish species, with vastly different life-histories. This ecological phenomenon may provide species resilience at the population level and needs to be considered in fisheries management initiatives. The movement of fishes is a fundamental aspect to consider when designing fishery management regimes. Unfortunately, traditional management strategies have often disregarded movement behaviour to the detriment of fish populations (Chapter 6). As a case study, the management of Lichia amia (Category I: wide-ranging) was evaluated in the context of its movement behaviour. Long-term catch-per-unit-effort (CPUE) datasets were examined for three South African recreational fishery sectors. The CPUE was standardised using generalized linear models (delta-Gamma/hurdle approach) to reduce the effect of factors other than abundance. Factors that were available for this purpose were year, month and locality/zone. Year was included in every model as the primary objective was to detect trends in abundance over time. Although standardised CPUE for all sectors showed an overall long-term decline, there was considerable variability in trends between the different recreational sectors and between datasets. Contrasting trends between competitive shore angling and general shore angling datasets were ascribed to hyperstability in competitive CPUE data. Hyperstability in this case was mostly influenced by rapidly improving technology, techniques and communication networks amongst competitive anglers. Month and locality were significant factors explaining the probability of catching L. amia. This suggests that the predictable aggregatory behaviour of this species could further compound the observed CPUE hyperstability. Although the CPUE responded positively for six years after implementation of the first minimum size and bag limits, and for one year after the decommercialisation of the species, these regulations and their amendments failed to arrest a long-term decline in the CPUE despite the ample evidence for hyperstability. It is clear from this case study that the predictable nature of wide-ranging behaviour in L. amia has made the population vulnerable to exploitation. This has led to the demise in the population, which could have been worse if not for the occurrence of intra-population variability in its movement behaviour, which may provide some measure of resilience.
- Full Text:
- Date Issued: 2018
- Authors: Maggs, Jade Quinton
- Date: 2018
- Subjects: Fishery management -- Africa, Southern , Fisheries -- Africa, Southern , Fisheries -- Catch effort , Fisheries -- Environmental aspects , Fisheries --Monitoring , Biotelemetry , Sustainable fisheries -- Africa, Southern , Overfishing -- Africa, Southern
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60574 , vital:27798
- Description: Movement of fishes is an integral part of their daily life, but has significant implications for fishery management. As with nearly all coastal countries, South Africa relies on coastal fisheries as a renewable resource, but many stocks have been overexploited for decades. Although it has long been recognised that an understanding of fish movement is necessary for effective management, it is with some difficulty that the subject has been studied in the past. In recent years, however, improvements in technology have provided the means for more in-depth investigations into fish movement. This research has revealed a range of complex movement behaviours. Movement in fishes occurs on a variety of temporal and spatial scales leading to the characteristic patterns of distribution and abundance observed in marine ecosystems. Fishes move nearly constantly in search of food, shelter or reproductive opportunities. Observations of behaviours such as long-term site fidelity, longdistance migration and natal homing are enabling ecologists to understand patterns of distribution and abundance within a species' range. Fish movement around the South African coast has been studied on numerous occasions but this has largely been confined to studies on single species. Movement behaviour of multiple species has been studied, but this has been limited to spatially localised marine protected area research. There has been little attempt in southern Africa to synthesize interspecific movement behaviour over wide spatial scales.Unprecedented concern over the biological effects of overexploitation, together with rapid technological advances in biotelemetry, have provided the impetus for much research, on a global scale, into the movement of marine animals. I reviewed 101 marine and estuarine fish movement studies from southern Africa, published from 1928 to 2014, with the aim of synthesising research trends and findings. Trends showed an increasing emphasis on fish movement research in publications in the sub-tropical and warm-temperate biogeographic regions along the south and east coasts of southern Africa. Although 63% of publications featured only marine studies, research into fine-scale habitat use in estuaries has been on the increase, concomitant with increasing accessibility of biotelemetry. Overall, 26 fish families were identified in the surveyed literature with regionally endemic sparids featuring in 32% of the publications. Ten movement themes were identified in the surveyed literature, including broad-scale movement patterns, which featured in 68% of studies, followed by fine- scale habitat usage (33%) and protected areas (26%). The most prominent phenomenon, emerging from this research, is that of partial migration, which describes the occurrence of resident and migratory behaviour within a coexisting animal population. Substantial progress has also been made in unravelling the complexities of fine-scale movements in marine reserves and habitat usage in estuaries. While this knowledge has enabled more effective management of South Africa's multi-user, multi-species fisheries, focus should now be directed at improving our understanding of the commonalities in movement behaviour, the associated driving forces behind this behaviour and the extent of movement across reserve boundaries. Mark-recapture data, collected over the past 30 years by the Oceanographic Research Institute’s Cooperative Fish Tagging Project (ORICFTP), were used to investigate broad- scale movement patterns of 30 prominent coastal fishery species (Chapter 4). Fishes were tagged with plastic dart tags along the coastline of southern Africa from Angola to Mozambique. This exercise yielded more than 10000 recaptures. The 30 chosen species represented 14 families, although 12 species belonged to a single family (Sparidae). Overall, 67% of recaptures were reported from the original tagging locality and 73% were recorded within 5 km of the tagging locality. The remaining observations extended from 6-3000 km. Movements were assigned to four distance bins (0-5 km, 6-50km, 51-500km and >500 km) and modelled with an ordinal logistic regression. Species, life-stage (juvenile/adult) and time- at-liberty were included as predictor variables. Model coefficients were then included in a cluster analysis, which produced two primary groupings of species (Category I and II), with two sub-groupings (Category IIa and IIb). Category I species were characterised by wide-ranging movements, greatest median recapture length and highest trophic levels. Category II species were characterised by residency, lower median recapture length and lower trophic levels. These findings have implications for fisheries management. Exploitation of resident species may lead to localised depletion, but their diffuse spatial distribution may offer some resilience. In contrast, even localised targeting of migratory species may pose a population level risk if individuals are known to aggregate. Life-cycle diversity or intra-population variability describes the existence of alternative strategies or tactics among coexisting individuals within an animal population (Chapter 5). Partial migration is a specific case of life-cycle diversity where coexisting groups exhibit either resident or migratory (wide-ranging) behaviour within a single population. Mark- recapture data collected under the auspices of the ORICFTP were used to investigate the occurrence and nature of life-cycle diversity in the movement behaviour of five non- diadromous fish species around the coastline of southern Africa. Among the five species were three teleosts (Category I and IIa) and two elasmobranchs (Category I). A fish was considered to have remained resident if recaptured within 0-5 km after 365 days at liberty. A fish was considered to have undertaken a wide-ranging movement if recaptured more than 50 km away from the release site in 365 days or less. A total of 1848 individuals from the five study species were recaptured during the study, of which 73% of the observations were classified as being resident. Binomial logistic regression confirmed that species, life-stage (juvenile/adult) and ecoregion were significant (p < 0.001) predictors of the probability of wide-ranging behaviour. A Gaussian model confirmed that species and ecoregion were also significant (p < 0.001) predictors of direction and distance of wide-ranging movement. However, the direction and distance of wide-ranging movements in juveniles did not differ significantly (p > 0.05) to that of adults. The median growth rate was mostly greater in wide- ranging individuals; however, this was only statistically significant (p < 0.05) in two cases. These findings provide unequivocal evidence of life-cycle diversity in five fish species, with vastly different life-histories. This ecological phenomenon may provide species resilience at the population level and needs to be considered in fisheries management initiatives. The movement of fishes is a fundamental aspect to consider when designing fishery management regimes. Unfortunately, traditional management strategies have often disregarded movement behaviour to the detriment of fish populations (Chapter 6). As a case study, the management of Lichia amia (Category I: wide-ranging) was evaluated in the context of its movement behaviour. Long-term catch-per-unit-effort (CPUE) datasets were examined for three South African recreational fishery sectors. The CPUE was standardised using generalized linear models (delta-Gamma/hurdle approach) to reduce the effect of factors other than abundance. Factors that were available for this purpose were year, month and locality/zone. Year was included in every model as the primary objective was to detect trends in abundance over time. Although standardised CPUE for all sectors showed an overall long-term decline, there was considerable variability in trends between the different recreational sectors and between datasets. Contrasting trends between competitive shore angling and general shore angling datasets were ascribed to hyperstability in competitive CPUE data. Hyperstability in this case was mostly influenced by rapidly improving technology, techniques and communication networks amongst competitive anglers. Month and locality were significant factors explaining the probability of catching L. amia. This suggests that the predictable aggregatory behaviour of this species could further compound the observed CPUE hyperstability. Although the CPUE responded positively for six years after implementation of the first minimum size and bag limits, and for one year after the decommercialisation of the species, these regulations and their amendments failed to arrest a long-term decline in the CPUE despite the ample evidence for hyperstability. It is clear from this case study that the predictable nature of wide-ranging behaviour in L. amia has made the population vulnerable to exploitation. This has led to the demise in the population, which could have been worse if not for the occurrence of intra-population variability in its movement behaviour, which may provide some measure of resilience.
- Full Text:
- Date Issued: 2018
Naming in Germany in the 20th century: a sociological study of naming in times of social change, with a focus on statistical problems in empirical onomastic research
- Authors: Huschka, Denis
- Date: 2018
- Subjects: Onomastics , Names, Personal -- Germany , Names, German -- Etymology , Names, German -- Social aspects , German language -- Etymology -- Names , German Socio Economic Panel Study (SOEP)
- Language: German , English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63054 , vital:28359
- Description: In this thesis names are used as social indicators to observe social change in Germany in the 20th century. The German Socio Economic Panel Study (SOEP) offers the rare opportunity to analyse representative survey data of first names. The empirical results of the analyses in this thesis offer a comprehensive picture on how the naming reality in Germany looks like and how naming changed in a period of about 100 years. Names can serve as social indicators. It is demonstrated how chosen names mirror social change in the German society: Name choices have become less traditional and more individual. Over time names from other world regions and cultures have found their way into the German culture. There are more different names in use today than 100 years ago and the names have become more evenly distributed over the population. Today children are less likely to share their names with many of their peers. These are signs of an increasingly individualised, transnationalised modern behaviour of the people in contemporary Germany. Almost all of these developments started earlier and tend to be more pronounced for girl’s names. The secularisation of the German society - however - did not cause substantial changes in naming over time. Christian names still are used to the greatest extent, but – possibly – not because they are regarded as being of Christian origin. The analyses of the social-structural influences on naming touch on some effects of education and status. The analyses of differences in naming between the two German states during the time of division adds some evidence to the real-life experience that naming in the communist East Germany was much more oriented towards the free western hemisphere – a kind of silent protest. Obviously naming was a possibility to distance oneself from an un-loved regime. On a methodological level referring to onomastics, the so-called „Large Number of are Events-Zone (LNRE)“, a feature of the distribution of names that has mostly been handled inappropriately up to now, is discussed with respect to its effects on name statistics when using samples. An alternative approach is proposed for the appropriate handling of this feature. , In der vorliegenden Arbeit werden Vornamen als soziale Indikatoren benutzt, um gesellschaftlichen Wandel im 20. Jahrhundert zu beschreiben. Das Soziooekonomische Panel (SOEP) bietet die seltene Möglichkeit, Umfragedaten über die Vornamen der Deutschen repräsentativ auszuwerten. Die empirischen Ergebnisse der vorliegenden Arbeit bieten einen umfassenden Einblick in die deutsche Vornamensrealität und über die Entwicklungen der Namensvergabe in 100 Jahren. Namen sind soziale Indikatoren. Es wird aufgezeigt, wie die Namensgebung den sozialen Wandel in der deutschen Gesellschaft spiegelt: Namenwahlen weisen über die Zeit weniger traditionelle Bezüge auf, sie wurden individueller. Namen aus anderen Kulturen und Ländern fanden Eingang in die deutsche Kultur. Es werden mehr verschiedene Namen benutzt als vor 100 Jahren und die typischerweise hoch konzentrierten Verteilungen der Vornamen stellen sich über die Zeit etwas weniger konzentriert dar. Heute geborene Kinder teilen ihre Namen mit anteilig weniger anderen Kindern ihrer Kohorte. Dies sind Anzeichen für eine individualisierte, transnational orientierte moderne Gesellschaft. Fast alle dieser Entwicklungen sind für Mädchennamen früher und in deutlicherem Maße zu beobachten. Die Säkularisierung der deutschen Gesellschaft hat hingegen wenig Einfluss auf die Vornamenswahlen genommen. Nach wie vor werden vor allem christliche Namen vergeben, auch wenn der christliche Bezug unter Umständen nicht mehr der maßgebliche Grund für die Auswahl ist. Die Analyse der sozialstrukturellen Einflüsse auf Namenswahlen bestätigt einige Effekte von Bildung und Status der Mütter. Die Analyse der Unterschiede in der Namensgebung der beiden deutschen Staaten während der 40 jährigen Teilung zeigt, dass der lebensweltliche Eindruck einer zunehmenden West-Orientierung der Namenswahlen ostdeutscher Eltern nicht trügt. Offenbar waren westliche Namen eine Möglichkeit, sich vom ungeliebten Regime zu distanzieren. Auf einer statistisch-methodischen Ebene wird eine bislang in der empirischen Onomastik unrichtig gehandhabte Besonderheit von Vornamensverteilungen – die Large Number of Rare Events-Zone (LNRE) – diskutiert und Lösungsvorschläge für den statistisch korrekten Umgang mit dieser Besonderheit in Gruppenvergleichen auf der Basis von Stichproben vorgelegt.
- Full Text:
- Date Issued: 2018
- Authors: Huschka, Denis
- Date: 2018
- Subjects: Onomastics , Names, Personal -- Germany , Names, German -- Etymology , Names, German -- Social aspects , German language -- Etymology -- Names , German Socio Economic Panel Study (SOEP)
- Language: German , English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63054 , vital:28359
- Description: In this thesis names are used as social indicators to observe social change in Germany in the 20th century. The German Socio Economic Panel Study (SOEP) offers the rare opportunity to analyse representative survey data of first names. The empirical results of the analyses in this thesis offer a comprehensive picture on how the naming reality in Germany looks like and how naming changed in a period of about 100 years. Names can serve as social indicators. It is demonstrated how chosen names mirror social change in the German society: Name choices have become less traditional and more individual. Over time names from other world regions and cultures have found their way into the German culture. There are more different names in use today than 100 years ago and the names have become more evenly distributed over the population. Today children are less likely to share their names with many of their peers. These are signs of an increasingly individualised, transnationalised modern behaviour of the people in contemporary Germany. Almost all of these developments started earlier and tend to be more pronounced for girl’s names. The secularisation of the German society - however - did not cause substantial changes in naming over time. Christian names still are used to the greatest extent, but – possibly – not because they are regarded as being of Christian origin. The analyses of the social-structural influences on naming touch on some effects of education and status. The analyses of differences in naming between the two German states during the time of division adds some evidence to the real-life experience that naming in the communist East Germany was much more oriented towards the free western hemisphere – a kind of silent protest. Obviously naming was a possibility to distance oneself from an un-loved regime. On a methodological level referring to onomastics, the so-called „Large Number of are Events-Zone (LNRE)“, a feature of the distribution of names that has mostly been handled inappropriately up to now, is discussed with respect to its effects on name statistics when using samples. An alternative approach is proposed for the appropriate handling of this feature. , In der vorliegenden Arbeit werden Vornamen als soziale Indikatoren benutzt, um gesellschaftlichen Wandel im 20. Jahrhundert zu beschreiben. Das Soziooekonomische Panel (SOEP) bietet die seltene Möglichkeit, Umfragedaten über die Vornamen der Deutschen repräsentativ auszuwerten. Die empirischen Ergebnisse der vorliegenden Arbeit bieten einen umfassenden Einblick in die deutsche Vornamensrealität und über die Entwicklungen der Namensvergabe in 100 Jahren. Namen sind soziale Indikatoren. Es wird aufgezeigt, wie die Namensgebung den sozialen Wandel in der deutschen Gesellschaft spiegelt: Namenwahlen weisen über die Zeit weniger traditionelle Bezüge auf, sie wurden individueller. Namen aus anderen Kulturen und Ländern fanden Eingang in die deutsche Kultur. Es werden mehr verschiedene Namen benutzt als vor 100 Jahren und die typischerweise hoch konzentrierten Verteilungen der Vornamen stellen sich über die Zeit etwas weniger konzentriert dar. Heute geborene Kinder teilen ihre Namen mit anteilig weniger anderen Kindern ihrer Kohorte. Dies sind Anzeichen für eine individualisierte, transnational orientierte moderne Gesellschaft. Fast alle dieser Entwicklungen sind für Mädchennamen früher und in deutlicherem Maße zu beobachten. Die Säkularisierung der deutschen Gesellschaft hat hingegen wenig Einfluss auf die Vornamenswahlen genommen. Nach wie vor werden vor allem christliche Namen vergeben, auch wenn der christliche Bezug unter Umständen nicht mehr der maßgebliche Grund für die Auswahl ist. Die Analyse der sozialstrukturellen Einflüsse auf Namenswahlen bestätigt einige Effekte von Bildung und Status der Mütter. Die Analyse der Unterschiede in der Namensgebung der beiden deutschen Staaten während der 40 jährigen Teilung zeigt, dass der lebensweltliche Eindruck einer zunehmenden West-Orientierung der Namenswahlen ostdeutscher Eltern nicht trügt. Offenbar waren westliche Namen eine Möglichkeit, sich vom ungeliebten Regime zu distanzieren. Auf einer statistisch-methodischen Ebene wird eine bislang in der empirischen Onomastik unrichtig gehandhabte Besonderheit von Vornamensverteilungen – die Large Number of Rare Events-Zone (LNRE) – diskutiert und Lösungsvorschläge für den statistisch korrekten Umgang mit dieser Besonderheit in Gruppenvergleichen auf der Basis von Stichproben vorgelegt.
- Full Text:
- Date Issued: 2018
Narrated experiences of the pre-termination of pregnancy counselling healthcare encounter in the Eastern Cape public health sector
- Mavuso, Jabulile Mary-Jane Jace
- Authors: Mavuso, Jabulile Mary-Jane Jace
- Date: 2018
- Subjects: Abortion counseling -- South Africa -- Eastern Cape , Abortion -- Psychological aspects , Abortion -- Social aspects , Pro-choice movement -- South Africa -- Eastern Cape , Reproductive rights -- South Africa -- Eastern Cape , Women -- Sexual behavior -- South Africa -- Eastern Cape , Women -- South Africa -- Social conditions
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62928 , vital:28311
- Description: Research that has been conducted about experiences of pre-abortion counselling tends to investigate either womxn's1 or healthcare providers' experiences separately, with research on womxn's experiences of abortion and abortion counselling dominating this area of research. Although some of the studies on womxn's abortion experiences have explored womxn's experiences of interactions between themselves and healthcare providers, these aspects have been underreported. To my knowledge, research that also explores womxn's interactions among themselves in the waiting room has not been done. Furthermore, research that explores the pre-termination of pregnancy healthcare encounter, where womxn's and healthcare providers' experiences of waiting room interactions and of pre-abortion counselling practices are seen as interrelated, has not been conducted. Research that has been conducted among womxn's experiences show that womxn have varying experiences of pre-abortion counselling, with some finding it useful while other womxn have found it to be lacking in relevance to their specific situation or needs. Research conducted among healthcare providers also points to varying experiences, with some healthcare providers stratifying womxn's reasons for abortion according to the acceptability of the request. This study explores health service providers’ and womxn’s narrated experiences of the pre-termination of pregnancy healthcare encounter (waiting room interactions and pre-abortion counselling) in the Eastern Cape public health sector. An African feminist post-structural approach, which enables analysis of how discursive structures and power relations may underpin African womxn's experiences of oppression and resistance, was used. Fusing this approach with a narrative-discursive analysis, enabled an exploration of the discursive resources drawn upon and the power relations referred to by participants when constructing micro-narratives and accounts of their experiences of waiting room interactions and pre-abortion counselling practices. This fusion enabled an understanding of the micro (individual) and macro (social) and how they interact and come to bear on experiences of the pre-abortion counselling healthcare encounter. Womxn's micro-narratives and healthcare providers' accounts were compared for convergences and divergences in the pre-abortion counselling practices they described. The implications of these convergences and divergences and of the power relations referred to by participants for pre-abortion counselling service provision are discussed. The research referred to in this study were conducted in contexts where abortion is legal, although the conditions under which it may be accessed differ across and within contexts. This present study is contextualised by the Choice on Termination of Pregnancy Act No. 92 of 1996 which legalises abortion and stipulates that abortion counselling should be made available to womxn but should be non-mandatory and non-directive. Data were collected at three abortion facilities located in public hospitals in the Eastern Cape. Open-ended, semi-structured interviews were conducted with 30 womxn after they received pre-abortion counselling, and four healthcare providers involved in abortion service provision. Data were analysed using an extended narrative-discursive approach which entailed exploring patterns in and across participants' talk. These patterns took the form of discursive resources (discourses and the subject positions they made available, and canonical narratives), power relations, and micro-narratives and accounts of their experiences of pre-abortion counselling practices and waiting room interactions. Participants described the following pre-abortion counselling practices: information-giving practices, consent practices, administering of LARCs, a waiting period and third-party involvement. In describing these processes, participants drew on an awfulisation of abortion discourse, moralising discourses, pronatalist discourses, and liberal discourses to construct (micro-)narratives in which liberal, pastoral and authoritarian counselling practices and power relations were constructed and referred to. In their micro-narratives, most womxn described the counselling as informative, beneficial and healing whilst also describing shock, hurt, pain and distress at the various kinds of information they received. Healthcare providers drew on discourses and canonical narratives (such as the hero and personal testimony) to justify liberal, pastoral and authoritarian counselling practices which were underpinned by constructing abortion and unintended pregnancy as problematic. The pre-abortion counselling practices that were described were directive in two ways: the coercion of contraceptive uptake post-abortion, and information provision practices which effectively work to delegitimise and persuade womxn against abortion.
- Full Text:
- Date Issued: 2018
- Authors: Mavuso, Jabulile Mary-Jane Jace
- Date: 2018
- Subjects: Abortion counseling -- South Africa -- Eastern Cape , Abortion -- Psychological aspects , Abortion -- Social aspects , Pro-choice movement -- South Africa -- Eastern Cape , Reproductive rights -- South Africa -- Eastern Cape , Women -- Sexual behavior -- South Africa -- Eastern Cape , Women -- South Africa -- Social conditions
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62928 , vital:28311
- Description: Research that has been conducted about experiences of pre-abortion counselling tends to investigate either womxn's1 or healthcare providers' experiences separately, with research on womxn's experiences of abortion and abortion counselling dominating this area of research. Although some of the studies on womxn's abortion experiences have explored womxn's experiences of interactions between themselves and healthcare providers, these aspects have been underreported. To my knowledge, research that also explores womxn's interactions among themselves in the waiting room has not been done. Furthermore, research that explores the pre-termination of pregnancy healthcare encounter, where womxn's and healthcare providers' experiences of waiting room interactions and of pre-abortion counselling practices are seen as interrelated, has not been conducted. Research that has been conducted among womxn's experiences show that womxn have varying experiences of pre-abortion counselling, with some finding it useful while other womxn have found it to be lacking in relevance to their specific situation or needs. Research conducted among healthcare providers also points to varying experiences, with some healthcare providers stratifying womxn's reasons for abortion according to the acceptability of the request. This study explores health service providers’ and womxn’s narrated experiences of the pre-termination of pregnancy healthcare encounter (waiting room interactions and pre-abortion counselling) in the Eastern Cape public health sector. An African feminist post-structural approach, which enables analysis of how discursive structures and power relations may underpin African womxn's experiences of oppression and resistance, was used. Fusing this approach with a narrative-discursive analysis, enabled an exploration of the discursive resources drawn upon and the power relations referred to by participants when constructing micro-narratives and accounts of their experiences of waiting room interactions and pre-abortion counselling practices. This fusion enabled an understanding of the micro (individual) and macro (social) and how they interact and come to bear on experiences of the pre-abortion counselling healthcare encounter. Womxn's micro-narratives and healthcare providers' accounts were compared for convergences and divergences in the pre-abortion counselling practices they described. The implications of these convergences and divergences and of the power relations referred to by participants for pre-abortion counselling service provision are discussed. The research referred to in this study were conducted in contexts where abortion is legal, although the conditions under which it may be accessed differ across and within contexts. This present study is contextualised by the Choice on Termination of Pregnancy Act No. 92 of 1996 which legalises abortion and stipulates that abortion counselling should be made available to womxn but should be non-mandatory and non-directive. Data were collected at three abortion facilities located in public hospitals in the Eastern Cape. Open-ended, semi-structured interviews were conducted with 30 womxn after they received pre-abortion counselling, and four healthcare providers involved in abortion service provision. Data were analysed using an extended narrative-discursive approach which entailed exploring patterns in and across participants' talk. These patterns took the form of discursive resources (discourses and the subject positions they made available, and canonical narratives), power relations, and micro-narratives and accounts of their experiences of pre-abortion counselling practices and waiting room interactions. Participants described the following pre-abortion counselling practices: information-giving practices, consent practices, administering of LARCs, a waiting period and third-party involvement. In describing these processes, participants drew on an awfulisation of abortion discourse, moralising discourses, pronatalist discourses, and liberal discourses to construct (micro-)narratives in which liberal, pastoral and authoritarian counselling practices and power relations were constructed and referred to. In their micro-narratives, most womxn described the counselling as informative, beneficial and healing whilst also describing shock, hurt, pain and distress at the various kinds of information they received. Healthcare providers drew on discourses and canonical narratives (such as the hero and personal testimony) to justify liberal, pastoral and authoritarian counselling practices which were underpinned by constructing abortion and unintended pregnancy as problematic. The pre-abortion counselling practices that were described were directive in two ways: the coercion of contraceptive uptake post-abortion, and information provision practices which effectively work to delegitimise and persuade womxn against abortion.
- Full Text:
- Date Issued: 2018
On high-altitude and high- latitude frost environments
- Authors: Hansen, Christel Dorothee
- Date: 2018
- Subjects: Frost -- Drakensberg Mountains , Frost -- Prince Edward Islands -- Marion Island , Frost -- Antarctica -- Queen Maud Land , Climatic geomorphology -- Southern Hemisphere , Permafrost -- Southern Hemisphere , Periglacial processes -- Southern Hemisphere , Frost environments -- Southern Hemisphere
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62383 , vital:28169
- Description: Frost environments occur throughout the world, with associated processes occurring across climatic zones. Climatic geomorphology proposes that climatic zones, largely derived from annual average air temperature and precipitation values, have specific landforms and processes active within that zone. This study offers unique insights into the frost environments of three locations in the Southern Hemisphere, namely the Eastern Cape Drakensberg of South Africa, sub-Antarctic Marion Island, and Dronning Maud Land of Antarctica. The Drakensberg ranges from temperate to alpine, Marion Island is hyper-maritime, and Dronning Maud Land a polar desert. Drivers and forcings on the ground frost regime are identified, as are future climatic scenarios. Altitude and latitude were identified as the most important locational drivers, while air temperature showed highest correlation with freezing events. The initiation of a freeze event correlated strongly with maximum ground temperatures. Vegetation cover was found to ameliorate frost cycles, thereby increasing ground temperatures. Dronning Maud Land of Antarctica is characterised by annual frost (permafrost), with limited seasonal thaw in summer. Thawing cycles reflected the depth of the active layer, which ranged from just under 60 cm for Robertskollen (at lowest altitude) to less than 15 cm on Slettfjell (at greatest altitude). Marion Island had the most active frost environment, exhibiting both seasonal frost, and ubiquitous shallow diurnal frost cycles. The Drakensberg were largely frost-free, with limited seasonal frost and few diurnal freeze- thaw events. Diurnal frost processes were found to be azonal, and present at all three study locations. Evidence of landforms derived from diurnal frost processes were evident in each zone. Equifinality/convergence of form was present to a degree. The presence of patterned ground, which was not wholly derived from frost processes, suggests a measure of equifinality. Furthermore, openwork block deposits, of which not all are either blockstreams nor blockfields, are not necessarily the result of frost processes. The periglacial environment is poorly defined and methods to delineate this environment, as well as other climatic zones, should include additional parameters. Delineating zones on annual (and limited) monthly averages based on predominantly temperature, is not sufficient. While concepts of climatic geomorphology may be applied in a general sense, this framework is not suited to working at smaller scales. Specifically, periglacial environments should be delineated using ground moisture, as well as air temperature. Furthermore, vegetation and snow cover are important, as are soil textural properties.
- Full Text:
- Date Issued: 2018
- Authors: Hansen, Christel Dorothee
- Date: 2018
- Subjects: Frost -- Drakensberg Mountains , Frost -- Prince Edward Islands -- Marion Island , Frost -- Antarctica -- Queen Maud Land , Climatic geomorphology -- Southern Hemisphere , Permafrost -- Southern Hemisphere , Periglacial processes -- Southern Hemisphere , Frost environments -- Southern Hemisphere
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62383 , vital:28169
- Description: Frost environments occur throughout the world, with associated processes occurring across climatic zones. Climatic geomorphology proposes that climatic zones, largely derived from annual average air temperature and precipitation values, have specific landforms and processes active within that zone. This study offers unique insights into the frost environments of three locations in the Southern Hemisphere, namely the Eastern Cape Drakensberg of South Africa, sub-Antarctic Marion Island, and Dronning Maud Land of Antarctica. The Drakensberg ranges from temperate to alpine, Marion Island is hyper-maritime, and Dronning Maud Land a polar desert. Drivers and forcings on the ground frost regime are identified, as are future climatic scenarios. Altitude and latitude were identified as the most important locational drivers, while air temperature showed highest correlation with freezing events. The initiation of a freeze event correlated strongly with maximum ground temperatures. Vegetation cover was found to ameliorate frost cycles, thereby increasing ground temperatures. Dronning Maud Land of Antarctica is characterised by annual frost (permafrost), with limited seasonal thaw in summer. Thawing cycles reflected the depth of the active layer, which ranged from just under 60 cm for Robertskollen (at lowest altitude) to less than 15 cm on Slettfjell (at greatest altitude). Marion Island had the most active frost environment, exhibiting both seasonal frost, and ubiquitous shallow diurnal frost cycles. The Drakensberg were largely frost-free, with limited seasonal frost and few diurnal freeze- thaw events. Diurnal frost processes were found to be azonal, and present at all three study locations. Evidence of landforms derived from diurnal frost processes were evident in each zone. Equifinality/convergence of form was present to a degree. The presence of patterned ground, which was not wholly derived from frost processes, suggests a measure of equifinality. Furthermore, openwork block deposits, of which not all are either blockstreams nor blockfields, are not necessarily the result of frost processes. The periglacial environment is poorly defined and methods to delineate this environment, as well as other climatic zones, should include additional parameters. Delineating zones on annual (and limited) monthly averages based on predominantly temperature, is not sufficient. While concepts of climatic geomorphology may be applied in a general sense, this framework is not suited to working at smaller scales. Specifically, periglacial environments should be delineated using ground moisture, as well as air temperature. Furthermore, vegetation and snow cover are important, as are soil textural properties.
- Full Text:
- Date Issued: 2018
Perceptions of Ulwaluko in a Liberal Democratic State: is multiculturalism beneficial to AmaXhosa women in the Eastern Cape province of South Africa?
- Authors: Gogela, Kholisa B
- Date: 2018
- Subjects: Initiation rites -- South Africa -- Eastern Cape , Circumcision -- South Africa -- Eastern Cape , Stigma (Social psychology) -- South Africa -- Eastern Cape , Xhosa (African people) -- South Africa -- Eastern Cape , Women -- Attitudes , Multiculturalism -- South Africa -- Eastern Cape , Women's rights -- South Africa -- Eastern Cape , Male domination (Social structure) -- South Africa -- Eastern Cape , Sex discrimination against women -- South Africa -- Eastern Cape , Ulwaluko
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61780 , vital:28059
- Description: This exploratory qualitative study sought to investigate the views and perceptions of women on their experiences of ulwaluko, a traditional rite practised by amaXhosa in the Eastern Cape province of South Africa. Ulwaluko is also known as isiko lokwaluka or ukoluka in isiXhosa. The concept refers not only to the act of circumcision that occurs during the initiation ritual but the entire process a boy goes through in observing this practice. Ulwaluko is performed in the belief that it will transform boys into accountable and responsible citizens of the society who are fully committed and dedicated to the tenets and standards of nation building. All amaXhosa boys are expected to undergo this tradition to be considered men. Failure to go to the initiation school usually results in social stigma and complete banishment by the society. There is an abundance of literature on studies that have been conducted on male circumcision (and not ulwaluko) which is performed for hygiene and religious purposes worldwide. With regards to ulwaluko of amaXhosa, research studies that have been conducted appear to lean mainly towards biomedical and public health aspects of the ritual. There seems to be an even bigger proportion of studies whose objective was to examine the relationship between circumcision and HIV/AIDS. From the literature review, it was not difficult to observe the pervasive paucity of research studies on women in relation to initiation (and that of amaXhosa in particular), with regards to their inclusion or exclusion in the practice, their feelings, perceptions, experiences and attitudes towards the custom. It is for this reason that I found it crucial to conduct this study. The main research question I sought to answer in this investigation was: are the human rights and gender equality rights of women, as entrenched in the multicultural principles that underpin South Africa’s liberal, democratic order, adequately protected? In other words, could the individual rights of women (or gender rights) that are endorsed by liberalism, be deferred in the interest of respecting traditions and cultural values associated with ulwaluko? And if they are, I further ask: could the deferral of such rights be legitimate in the face of South Africa’s legal framework? The nature of this study places it in the qualitative paradigm, and interpretive phenomenology was the most appropriate research design to carry out the investigation. Multiculturalism is a principle at the centre of liberalism, and as a framework for this study, I contrast and reconcile it with feminism. While multiculturalism is concerned with protecting traditions and cultures of minority groups, feminism is concerned about women’s emancipation. I used the non-probability purposive sampling to select participants who were rich in information; and I made use of community structures to gain entry into research sites and to seek permission to carry out the investigation. I conducted the pilot study in Mdantsane, a township in the Buffalo City Municipality; and I gathered data in two research sites, namely: Flagstaff in Mpondondoland and Grahamstown in the Makana Local Municipality. I employed two qualitative methods to collect information, namely: focus group discussions (FGDs) and semi-structured in-depth interviews. A total of 70 participants took part in the study. 60 women participated in 8 focus groups and 10 participated in-depth interviews. Their ages ranged between 31 and 82 years. I recorded all the FGDs and semi-structured in-depth interviews that I conducted, for ease of transcription and translation. To interprete and analyze data, I applied the general inductive approach which I later substantiated with the use of NVivo 8, a computer assisted qualitative data analysis (CAQDAS). This resulted in the identification of four themes and their related sub-themes which I compared and contrasted with literature review and the theoretical framework, so as to make sense of the information I generated from the data collection process. I also discussed the results in line with the four goals of the study. The findings of this inquiry suggest a number of factors about ulwaluko, the following being the most significant: that firstly, although the rite is espoused and celebrated by some women as a significant cultural practice among amaXhosa, for others it is synonymous with patriarchy and hegemony. Secondly, women felt largely excluded, claiming that they were relegated to a subordinate position in society. For this reason, as well as because of the biomedical and other socio-political concerns associated with the practice, some women resented the custom. Thirdly, participants were divided about whether the practice should be continued or abolished; and these differences manifested within and between different regions. Fourthly, the results also demonstrated that the norms and values applied in ulwaluko are in contravention of the fundamental principles of a liberal state in that universal human rights are infringed upon through exclusionary practices. In this case the woman’s voice is muted; and this results in the denial of human agency. The study however, also revealed the emergence of shifting patterns in some parts of the province where an effort to include women appears to be taking place. Fifth and last, the enquiry demonstrated that ulwaluko is deeply entrenched among amaXhosa; that it has stood the test of time and is unlikely to be discontinued. Based on the results, I recommend that creative and transformative ways of addressing the evident clash between the provision of individual rights by the state and the recognition of ulwaluko as a cultural practice (which is perceived by some as harmful to women) be sought. To achieve this objective I make the following recommendations: 1) establishment and utilization of gender equality programmes; 2) modification of values and norms of the custom; 3) representation of women in decision-making structures; 4) establishment of collaborative networks; 5) widening of access to services (such as chapter nine institutions and national gender machinery); 6) documentation and sharing of effective and inclusive practices as well as; 7) creating awareness on initiation legislation.
- Full Text:
- Date Issued: 2018
- Authors: Gogela, Kholisa B
- Date: 2018
- Subjects: Initiation rites -- South Africa -- Eastern Cape , Circumcision -- South Africa -- Eastern Cape , Stigma (Social psychology) -- South Africa -- Eastern Cape , Xhosa (African people) -- South Africa -- Eastern Cape , Women -- Attitudes , Multiculturalism -- South Africa -- Eastern Cape , Women's rights -- South Africa -- Eastern Cape , Male domination (Social structure) -- South Africa -- Eastern Cape , Sex discrimination against women -- South Africa -- Eastern Cape , Ulwaluko
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61780 , vital:28059
- Description: This exploratory qualitative study sought to investigate the views and perceptions of women on their experiences of ulwaluko, a traditional rite practised by amaXhosa in the Eastern Cape province of South Africa. Ulwaluko is also known as isiko lokwaluka or ukoluka in isiXhosa. The concept refers not only to the act of circumcision that occurs during the initiation ritual but the entire process a boy goes through in observing this practice. Ulwaluko is performed in the belief that it will transform boys into accountable and responsible citizens of the society who are fully committed and dedicated to the tenets and standards of nation building. All amaXhosa boys are expected to undergo this tradition to be considered men. Failure to go to the initiation school usually results in social stigma and complete banishment by the society. There is an abundance of literature on studies that have been conducted on male circumcision (and not ulwaluko) which is performed for hygiene and religious purposes worldwide. With regards to ulwaluko of amaXhosa, research studies that have been conducted appear to lean mainly towards biomedical and public health aspects of the ritual. There seems to be an even bigger proportion of studies whose objective was to examine the relationship between circumcision and HIV/AIDS. From the literature review, it was not difficult to observe the pervasive paucity of research studies on women in relation to initiation (and that of amaXhosa in particular), with regards to their inclusion or exclusion in the practice, their feelings, perceptions, experiences and attitudes towards the custom. It is for this reason that I found it crucial to conduct this study. The main research question I sought to answer in this investigation was: are the human rights and gender equality rights of women, as entrenched in the multicultural principles that underpin South Africa’s liberal, democratic order, adequately protected? In other words, could the individual rights of women (or gender rights) that are endorsed by liberalism, be deferred in the interest of respecting traditions and cultural values associated with ulwaluko? And if they are, I further ask: could the deferral of such rights be legitimate in the face of South Africa’s legal framework? The nature of this study places it in the qualitative paradigm, and interpretive phenomenology was the most appropriate research design to carry out the investigation. Multiculturalism is a principle at the centre of liberalism, and as a framework for this study, I contrast and reconcile it with feminism. While multiculturalism is concerned with protecting traditions and cultures of minority groups, feminism is concerned about women’s emancipation. I used the non-probability purposive sampling to select participants who were rich in information; and I made use of community structures to gain entry into research sites and to seek permission to carry out the investigation. I conducted the pilot study in Mdantsane, a township in the Buffalo City Municipality; and I gathered data in two research sites, namely: Flagstaff in Mpondondoland and Grahamstown in the Makana Local Municipality. I employed two qualitative methods to collect information, namely: focus group discussions (FGDs) and semi-structured in-depth interviews. A total of 70 participants took part in the study. 60 women participated in 8 focus groups and 10 participated in-depth interviews. Their ages ranged between 31 and 82 years. I recorded all the FGDs and semi-structured in-depth interviews that I conducted, for ease of transcription and translation. To interprete and analyze data, I applied the general inductive approach which I later substantiated with the use of NVivo 8, a computer assisted qualitative data analysis (CAQDAS). This resulted in the identification of four themes and their related sub-themes which I compared and contrasted with literature review and the theoretical framework, so as to make sense of the information I generated from the data collection process. I also discussed the results in line with the four goals of the study. The findings of this inquiry suggest a number of factors about ulwaluko, the following being the most significant: that firstly, although the rite is espoused and celebrated by some women as a significant cultural practice among amaXhosa, for others it is synonymous with patriarchy and hegemony. Secondly, women felt largely excluded, claiming that they were relegated to a subordinate position in society. For this reason, as well as because of the biomedical and other socio-political concerns associated with the practice, some women resented the custom. Thirdly, participants were divided about whether the practice should be continued or abolished; and these differences manifested within and between different regions. Fourthly, the results also demonstrated that the norms and values applied in ulwaluko are in contravention of the fundamental principles of a liberal state in that universal human rights are infringed upon through exclusionary practices. In this case the woman’s voice is muted; and this results in the denial of human agency. The study however, also revealed the emergence of shifting patterns in some parts of the province where an effort to include women appears to be taking place. Fifth and last, the enquiry demonstrated that ulwaluko is deeply entrenched among amaXhosa; that it has stood the test of time and is unlikely to be discontinued. Based on the results, I recommend that creative and transformative ways of addressing the evident clash between the provision of individual rights by the state and the recognition of ulwaluko as a cultural practice (which is perceived by some as harmful to women) be sought. To achieve this objective I make the following recommendations: 1) establishment and utilization of gender equality programmes; 2) modification of values and norms of the custom; 3) representation of women in decision-making structures; 4) establishment of collaborative networks; 5) widening of access to services (such as chapter nine institutions and national gender machinery); 6) documentation and sharing of effective and inclusive practices as well as; 7) creating awareness on initiation legislation.
- Full Text:
- Date Issued: 2018
Performance evaluation and cost analysis of subsurface flow constructed wetlands designed for ammonium-nitrogen removal
- Authors: Tebitendwa, Sylvie Muwanga
- Date: 2018
- Subjects: Sewage Purification Nitrogen removal , Constructed wetlands , Bioremediation , Sewage lagoons , Coal mine waste
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61808 , vital:28062
- Description: Subsurface flow constructed wetlands (SSF CWs) is a low-cost, environmentally friendly sanitation technology for on-site treatment of domestic/municipal sewage. However, these systems are apparently unable to produce treated water of a quality suitable for discharge particularly in terms of nitrogen concentration, which has been attributed to design and operation based on biological oxygen demand as the parameter of choice. The aim of this study was to evaluate the performance, support medium, and techno-economics of a vertical- horizontal (V-H) SSF hybrid CW designed and operated using ammonium-nitrogen (NH4+-N) as the major parameter. Two pilot scale V-H SSF hybrid CWs were designed, constructed, and the performance of each monitored over two seasons and under two phases i.e. an initiation phase, and an optimization phase. Laboratory-scale horizontal SSF CWs were used to evaluate the support medium while the techno-economic study was framed to determine the cost effectiveness of V-H SSF hybrid CWs relative to high rate algal oxidation pond (HRAOP) systems to increase capacity of overloaded and/or under-performing waste stabilization pond (WSP) sewage treatment plants. Results revealed that under optimal operating conditions of hydraulic loading rate, hydraulic retention, and influent NH4+-N loading rate, treated water from the V-H SSF hybrid CWs achieved a quality commensurate with current South African standards for discharge into a surface water resource for all parameters except chemical oxygen demand and faecal coliforms. This suggests that NH4+-N is an important design and operational parameter for SSF CWs treating municipal sewage that is characterised as weak in terms of NH4+-N with a requirement of only simple disinfection such as chlorination to eliminate faecal coliforms. Use of discard coal to replace gravel as support medium in horizontal SSF CWs revealed an overall reduction in elemental composition of the discard coal support medium but without compromising water quality. This result strongly supports use of discard coal as an appropriate substrate for SSF CWs to achieve acceptable water quality. Furthermore, simultaneous degradation of discard coal during wastewater treatment demonstrates the versatility of SSF CWs for use in bio-remediation and pollution control. Finally, a technoeconomic assessment of V-H SSF hybrid CWs and a HRAOP series was carried out to determine the suitability of each process to increase capacity by mitigating dysfunctional and/or overloaded WSP sewage treatment plants. Analysis revealed that the quality of treated water from both systems was within the South African General Authorization standards for discharge to a surface water resource. Even so, each technology system presented its own set of limitations including; the inability to satisfactorily remove NH4+-N and chemical oxygen demand (i.e. for V-H SSF hybrid CWs) and total suspended solids and faecal coliforms (i.e. for HRAOPs), and a requirement for substantial land footprint while, HRAOPs required significantly less capital than V-H SSF hybrid CWs for implementation. The latter suggests that HRAOPs could be preferred over V-H SSF hybrid CWs as a technology of choice to increase the capacity of overloaded WSP sewage treatment plants especially where financial resources are limited. Overall, the results of this thesis indicate the potential to use NH4+-N as a design parameter in constructing SSF CWs treating weak strength municipal sewage (i.e. in terms of NH4+-N concentration) and to supplant gravel as the treatment media with industrial waste material like discard coal to achieve wastewater treatment, bio-remediation, and pollution control. The results of this work are discussed in terms of using SSF CWs as a passive and resilient technology for the treatment of domestic sewage in sub-Saharan Africa.
- Full Text:
- Date Issued: 2018
- Authors: Tebitendwa, Sylvie Muwanga
- Date: 2018
- Subjects: Sewage Purification Nitrogen removal , Constructed wetlands , Bioremediation , Sewage lagoons , Coal mine waste
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61808 , vital:28062
- Description: Subsurface flow constructed wetlands (SSF CWs) is a low-cost, environmentally friendly sanitation technology for on-site treatment of domestic/municipal sewage. However, these systems are apparently unable to produce treated water of a quality suitable for discharge particularly in terms of nitrogen concentration, which has been attributed to design and operation based on biological oxygen demand as the parameter of choice. The aim of this study was to evaluate the performance, support medium, and techno-economics of a vertical- horizontal (V-H) SSF hybrid CW designed and operated using ammonium-nitrogen (NH4+-N) as the major parameter. Two pilot scale V-H SSF hybrid CWs were designed, constructed, and the performance of each monitored over two seasons and under two phases i.e. an initiation phase, and an optimization phase. Laboratory-scale horizontal SSF CWs were used to evaluate the support medium while the techno-economic study was framed to determine the cost effectiveness of V-H SSF hybrid CWs relative to high rate algal oxidation pond (HRAOP) systems to increase capacity of overloaded and/or under-performing waste stabilization pond (WSP) sewage treatment plants. Results revealed that under optimal operating conditions of hydraulic loading rate, hydraulic retention, and influent NH4+-N loading rate, treated water from the V-H SSF hybrid CWs achieved a quality commensurate with current South African standards for discharge into a surface water resource for all parameters except chemical oxygen demand and faecal coliforms. This suggests that NH4+-N is an important design and operational parameter for SSF CWs treating municipal sewage that is characterised as weak in terms of NH4+-N with a requirement of only simple disinfection such as chlorination to eliminate faecal coliforms. Use of discard coal to replace gravel as support medium in horizontal SSF CWs revealed an overall reduction in elemental composition of the discard coal support medium but without compromising water quality. This result strongly supports use of discard coal as an appropriate substrate for SSF CWs to achieve acceptable water quality. Furthermore, simultaneous degradation of discard coal during wastewater treatment demonstrates the versatility of SSF CWs for use in bio-remediation and pollution control. Finally, a technoeconomic assessment of V-H SSF hybrid CWs and a HRAOP series was carried out to determine the suitability of each process to increase capacity by mitigating dysfunctional and/or overloaded WSP sewage treatment plants. Analysis revealed that the quality of treated water from both systems was within the South African General Authorization standards for discharge to a surface water resource. Even so, each technology system presented its own set of limitations including; the inability to satisfactorily remove NH4+-N and chemical oxygen demand (i.e. for V-H SSF hybrid CWs) and total suspended solids and faecal coliforms (i.e. for HRAOPs), and a requirement for substantial land footprint while, HRAOPs required significantly less capital than V-H SSF hybrid CWs for implementation. The latter suggests that HRAOPs could be preferred over V-H SSF hybrid CWs as a technology of choice to increase the capacity of overloaded WSP sewage treatment plants especially where financial resources are limited. Overall, the results of this thesis indicate the potential to use NH4+-N as a design parameter in constructing SSF CWs treating weak strength municipal sewage (i.e. in terms of NH4+-N concentration) and to supplant gravel as the treatment media with industrial waste material like discard coal to achieve wastewater treatment, bio-remediation, and pollution control. The results of this work are discussed in terms of using SSF CWs as a passive and resilient technology for the treatment of domestic sewage in sub-Saharan Africa.
- Full Text:
- Date Issued: 2018
Preimages for SHA-1
- Authors: Motara, Yusuf Moosa
- Date: 2018
- Subjects: Data encryption (Computer science) , Computer security -- Software , Hashing (Computer science) , Data compression (Computer science) , Preimage , Secure Hash Algorithm 1 (SHA-1)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/57885 , vital:27004
- Description: This research explores the problem of finding a preimage — an input that, when passed through a particular function, will result in a pre-specified output — for the compression function of the SHA-1 cryptographic hash. This problem is much more difficult than the problem of finding a collision for a hash function, and preimage attacks for very few popular hash functions are known. The research begins by introducing the field and giving an overview of the existing work in the area. A thorough analysis of the compression function is made, resulting in alternative formulations for both parts of the function, and both statistical and theoretical tools to determine the difficulty of the SHA-1 preimage problem. Different representations (And- Inverter Graph, Binary Decision Diagram, Conjunctive Normal Form, Constraint Satisfaction form, and Disjunctive Normal Form) and associated tools to manipulate and/or analyse these representations are then applied and explored, and results are collected and interpreted. In conclusion, the SHA-1 preimage problem remains unsolved and insoluble for the foreseeable future. The primary issue is one of efficient representation; despite a promising theoretical difficulty, both the diffusion characteristics and the depth of the tree stand in the way of efficient search. Despite this, the research served to confirm and quantify the difficulty of the problem both theoretically, using Schaefer's Theorem, and practically, in the context of different representations.
- Full Text:
- Date Issued: 2018
- Authors: Motara, Yusuf Moosa
- Date: 2018
- Subjects: Data encryption (Computer science) , Computer security -- Software , Hashing (Computer science) , Data compression (Computer science) , Preimage , Secure Hash Algorithm 1 (SHA-1)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/57885 , vital:27004
- Description: This research explores the problem of finding a preimage — an input that, when passed through a particular function, will result in a pre-specified output — for the compression function of the SHA-1 cryptographic hash. This problem is much more difficult than the problem of finding a collision for a hash function, and preimage attacks for very few popular hash functions are known. The research begins by introducing the field and giving an overview of the existing work in the area. A thorough analysis of the compression function is made, resulting in alternative formulations for both parts of the function, and both statistical and theoretical tools to determine the difficulty of the SHA-1 preimage problem. Different representations (And- Inverter Graph, Binary Decision Diagram, Conjunctive Normal Form, Constraint Satisfaction form, and Disjunctive Normal Form) and associated tools to manipulate and/or analyse these representations are then applied and explored, and results are collected and interpreted. In conclusion, the SHA-1 preimage problem remains unsolved and insoluble for the foreseeable future. The primary issue is one of efficient representation; despite a promising theoretical difficulty, both the diffusion characteristics and the depth of the tree stand in the way of efficient search. Despite this, the research served to confirm and quantify the difficulty of the problem both theoretically, using Schaefer's Theorem, and practically, in the context of different representations.
- Full Text:
- Date Issued: 2018
Scale-specific processes underlying the genetic population structure of seabirds in the tropical western Indian Ocean
- Authors: Danckwerts, Daniel Keith
- Date: 2018
- Subjects: Sea birds -- Indian Ocean , Sea birds -- Behavior -- Indian Ocean , Sea birds -- Mortality -- Indian Ocean , Sea birds -- Mortality -- Prevention , Sea birds -- Reproduction , Bird declines -- Indian Ocean , Sea birds -- Indian Ocean -- Effect of human beings on , Sooty tern , Red-footed booby , Pterodroma
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63944 , vital:28513
- Description: Global seabird populations have declined by 70%, since 1950, largely in response to human mediated threats. Identifying the pressures that the remaining populations face has therefore become a top priority. Many breeding colonies are now monitored annually, though others have been almost completely neglected. Considerable bias also exists towards higher latitude species, while fewer studies have been conducted on tropical groups. Beyond tracking population sizes, numerous knowledge gaps also exist that severely restrict conservation efforts. This includes the understanding of seabird meta-population structure and the processes underlying population divergence. The importance of these studies lies in the fact that the preservation of biodiversity requires the conservation of diversification processes. Generating this knowledge is therefore an important first step towards recognising responses to episodic disturbance and long-term environmental change, as well as recovery potential. In this context, the present study employed microsatellite analysis and ringing information to investigate the processes underlying the metapopulation structure of seabirds in the tropical western Indian Ocean. Three species were selected as proxies to cover a range of population sizes, distributional ranges, and intrinsic behavioural (e.g. migratory behaviour) and morphological (e.g. polymorphism) characteristics. These were the Sooty Tern (Onychoprion fuscatus), Red-footed Booby (Sula sula), and Barau’s Petrel (Pterodorma baraui). The overall objective was to provide insight into the mechanisms underlying divergence across a range of scales. Microsatellite information highlighted that genetic populations of the Red-footed Booby and Barau’s Petrel were weakly, though significantly, structured. For the Barau’s Petrel, this was supported by ringing information that indicated extreme colony fidelity. Some gene flow appears to occur among the breeding colonies of the Red-footed Booby, though the scale and frequency of this remains uncertain as banding information is insufficient at this stage. Nevertheless, though populations of both species were genetically structured, the processes underlying divergence were different. Extreme natal philopatry appears to have driven divergence between the two colonies of the Barau’s Petrel, while local selective forces (e.g. kleptoparasitism risk and/or selection against immigrants) appear to have isolated the three studied breeding colonies of the Red-footed Booby. Conversely, microsatellite information identified a total lack of genetic structure among breeding colonies of the Sooty Tern in the western Indian Ocean, and between colonies in the western Indian and Eastern Pacific Oceans. This accords with banding recoveries, which illustrate considerable inter-colony exchange of individuals among most islands of the Seychelles and between breeding colonies in the western Indian and West Pacific Oceans. The processes underlying the genetic population structure (or, in this case, lack thereof) in the Sooty Tern therefore appear to operate at extremely large scales. The species’ low natal philopatry and high dispersal capabilities, combined with an importance of social stimulation and a reliance on seasonally favourable marine conditions, appears to influence the decisions of where and when individual Sooty Terns choose to breed. Anthropogenic disturbance at breeding sites, particularly that related to egg harvesting activities, also appears to drive dispersal in the Sooty Tern. These results improve our understanding of the mechanisms underlying the genetic population structure in seabirds at low latitudes. However, numerous questions remain unanswered and warrant further study. Clear conservation implications were also identified for the three studied species. Nevertheless, caution should still be applied when extrapolating this information across other species.
- Full Text:
- Date Issued: 2018
- Authors: Danckwerts, Daniel Keith
- Date: 2018
- Subjects: Sea birds -- Indian Ocean , Sea birds -- Behavior -- Indian Ocean , Sea birds -- Mortality -- Indian Ocean , Sea birds -- Mortality -- Prevention , Sea birds -- Reproduction , Bird declines -- Indian Ocean , Sea birds -- Indian Ocean -- Effect of human beings on , Sooty tern , Red-footed booby , Pterodroma
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63944 , vital:28513
- Description: Global seabird populations have declined by 70%, since 1950, largely in response to human mediated threats. Identifying the pressures that the remaining populations face has therefore become a top priority. Many breeding colonies are now monitored annually, though others have been almost completely neglected. Considerable bias also exists towards higher latitude species, while fewer studies have been conducted on tropical groups. Beyond tracking population sizes, numerous knowledge gaps also exist that severely restrict conservation efforts. This includes the understanding of seabird meta-population structure and the processes underlying population divergence. The importance of these studies lies in the fact that the preservation of biodiversity requires the conservation of diversification processes. Generating this knowledge is therefore an important first step towards recognising responses to episodic disturbance and long-term environmental change, as well as recovery potential. In this context, the present study employed microsatellite analysis and ringing information to investigate the processes underlying the metapopulation structure of seabirds in the tropical western Indian Ocean. Three species were selected as proxies to cover a range of population sizes, distributional ranges, and intrinsic behavioural (e.g. migratory behaviour) and morphological (e.g. polymorphism) characteristics. These were the Sooty Tern (Onychoprion fuscatus), Red-footed Booby (Sula sula), and Barau’s Petrel (Pterodorma baraui). The overall objective was to provide insight into the mechanisms underlying divergence across a range of scales. Microsatellite information highlighted that genetic populations of the Red-footed Booby and Barau’s Petrel were weakly, though significantly, structured. For the Barau’s Petrel, this was supported by ringing information that indicated extreme colony fidelity. Some gene flow appears to occur among the breeding colonies of the Red-footed Booby, though the scale and frequency of this remains uncertain as banding information is insufficient at this stage. Nevertheless, though populations of both species were genetically structured, the processes underlying divergence were different. Extreme natal philopatry appears to have driven divergence between the two colonies of the Barau’s Petrel, while local selective forces (e.g. kleptoparasitism risk and/or selection against immigrants) appear to have isolated the three studied breeding colonies of the Red-footed Booby. Conversely, microsatellite information identified a total lack of genetic structure among breeding colonies of the Sooty Tern in the western Indian Ocean, and between colonies in the western Indian and Eastern Pacific Oceans. This accords with banding recoveries, which illustrate considerable inter-colony exchange of individuals among most islands of the Seychelles and between breeding colonies in the western Indian and West Pacific Oceans. The processes underlying the genetic population structure (or, in this case, lack thereof) in the Sooty Tern therefore appear to operate at extremely large scales. The species’ low natal philopatry and high dispersal capabilities, combined with an importance of social stimulation and a reliance on seasonally favourable marine conditions, appears to influence the decisions of where and when individual Sooty Terns choose to breed. Anthropogenic disturbance at breeding sites, particularly that related to egg harvesting activities, also appears to drive dispersal in the Sooty Tern. These results improve our understanding of the mechanisms underlying the genetic population structure in seabirds at low latitudes. However, numerous questions remain unanswered and warrant further study. Clear conservation implications were also identified for the three studied species. Nevertheless, caution should still be applied when extrapolating this information across other species.
- Full Text:
- Date Issued: 2018
Sepedi oral poetry with reference to kiba traditional dance of South Africa
- Authors: Maahlamela, Tebogo David
- Date: 2018
- Subjects: Northern Sotho poetry , Northern Sotho poetry -- History and criticism , Folk songs, Northern Sotho , Sound poetry -- South Africa , Archival materials -- Conservation and restoration , Spiritualism in literature , Cultural appropriation , Folk poetry, Northern Sotho , Kiba traditional dance , Kiba poetry
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63209 , vital:28381
- Description: Previous studies show that contrary to other African languages of fewer speakers, written poetry in Sepedi/Sesotho sa Leboa’s transition from oral to written did not only lag behind, its development was also slow, with less intense treatment. However, this scarcity is not of the actual oral material, but rather its documented version. Vast untreated material at various repositories such as the South African Broadcasting Corporation (SABC) library and the International Library of African Music (ILAM) are facing a risk of being lost due to limited resources and resourcefulness to digitalise them. Investigation of written poetry from 1906 to 2006 attests to the fact that in its written form, Sepedi/Sesotho sa Leboa poetry is still underdeveloped, dominated by “microwaved” collections aiming at nothing beyond meeting school prescription criteria. Calls have been made from the dominant South African poetry narrative that there are no innovative studies in the field of African languages, especially Sepedi/Sesotho sa Leboa. Musicological studies show that contemporary jazz artists have adopted and adapted kiba poetry into jazz music, which resulted into classics of all times. Intensive studies were conducted on such poetic kiba-influenced jazz, but the primary source remains a grey area. The analysis of selected kiba poems shows that kiba poetry is the richest poetic form in the Sepedi/Sesotho sa Leboa with its creative and artistic merit exceeds all other genres. The study further reveals that kiba poetry is the heart of Bapedi/Basotho ba Leboa spirituality, a heart without which some faith institutions will remain incomplete. Furthermore, kiba poetry embodies, among others, poetic genres rarely explored in the South African poetry milieu such as “sound poetry” and poetry of special metrical schemes, of dramatic and devotional essence. Scholarly attention is, therefore, recommended on this repertoire to explore the field beyond this preliminary study, so as to save as many kiba poems as possible, which will enrich the dwindling written poetry milieu. Literary excellence of the treated poems attests to the fact that the artistic wealth of kiba poetry is worthy of attention, and it has potential to transform not only the face of poetry in Sepedi/Sesotho sa Leboa, but of the entire South African poetry landscape.
- Full Text:
- Date Issued: 2018
- Authors: Maahlamela, Tebogo David
- Date: 2018
- Subjects: Northern Sotho poetry , Northern Sotho poetry -- History and criticism , Folk songs, Northern Sotho , Sound poetry -- South Africa , Archival materials -- Conservation and restoration , Spiritualism in literature , Cultural appropriation , Folk poetry, Northern Sotho , Kiba traditional dance , Kiba poetry
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63209 , vital:28381
- Description: Previous studies show that contrary to other African languages of fewer speakers, written poetry in Sepedi/Sesotho sa Leboa’s transition from oral to written did not only lag behind, its development was also slow, with less intense treatment. However, this scarcity is not of the actual oral material, but rather its documented version. Vast untreated material at various repositories such as the South African Broadcasting Corporation (SABC) library and the International Library of African Music (ILAM) are facing a risk of being lost due to limited resources and resourcefulness to digitalise them. Investigation of written poetry from 1906 to 2006 attests to the fact that in its written form, Sepedi/Sesotho sa Leboa poetry is still underdeveloped, dominated by “microwaved” collections aiming at nothing beyond meeting school prescription criteria. Calls have been made from the dominant South African poetry narrative that there are no innovative studies in the field of African languages, especially Sepedi/Sesotho sa Leboa. Musicological studies show that contemporary jazz artists have adopted and adapted kiba poetry into jazz music, which resulted into classics of all times. Intensive studies were conducted on such poetic kiba-influenced jazz, but the primary source remains a grey area. The analysis of selected kiba poems shows that kiba poetry is the richest poetic form in the Sepedi/Sesotho sa Leboa with its creative and artistic merit exceeds all other genres. The study further reveals that kiba poetry is the heart of Bapedi/Basotho ba Leboa spirituality, a heart without which some faith institutions will remain incomplete. Furthermore, kiba poetry embodies, among others, poetic genres rarely explored in the South African poetry milieu such as “sound poetry” and poetry of special metrical schemes, of dramatic and devotional essence. Scholarly attention is, therefore, recommended on this repertoire to explore the field beyond this preliminary study, so as to save as many kiba poems as possible, which will enrich the dwindling written poetry milieu. Literary excellence of the treated poems attests to the fact that the artistic wealth of kiba poetry is worthy of attention, and it has potential to transform not only the face of poetry in Sepedi/Sesotho sa Leboa, but of the entire South African poetry landscape.
- Full Text:
- Date Issued: 2018
Servant leadership: antecedent to Quality of Worklife of customer service frontline employees
- Authors: Bedser, Mark Bernard
- Date: 2018
- Subjects: Call center agents Servant leadership Customer Service -- Quality control Employee morale Job satisfaction Quality of work life
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62144 , vital:28132
- Description: Contact Centre agents operate in closely monitored and highly controlled environments and their work consists of solving service requests or assisting customers with information on products or services. Consequently their work involves a great deal of emotional labour and stress. It is not surprising then, that the working environment of the Contact Centre is reported to have a negative impact on the levels of Quality of Worklife of Contact Centre agents, and that in the Contact Centre context, it is likely that low levels of Quality of Worklife exist. It is argued that it is important for organisations to be particularly aware of the Quality of Worklife perceptions of their employees should they want to address Quality of Worklife levels and benefit from the positive consequences of higher levels of the construct. Numerous variables are reported to play either an antecedent, moderating, mediating, or consequential role in relation to the Quality of Worklife construct. A systems model of Quality of Worklife is developed, which illustrates the inter-relationships of these variables and how they affect and are affected by the Quality of Worklife construct. It is argued that leadership is an important antecedent to Quality of Worklife, and this is the antecedent of interest in this study. It is proposed that it is not just any leadership that will contribute to an improved Quality of Worklife, particularly within a challenging context such as the Contact Centre environment. Rather, it is suggested that certain qualities of leaders will have a greater influence on Quality of Worklife. For example, leaders who focus on relationships and are caring - characteristics associated with servant leaders - are deemed more suitable for the Contact Centre context. The research also proposes that there are close associations between Servant Leadership and Trust, which in turn has the potential to affect Quality of Worklife positively. It is argued, therefore, that Trust mediates the relationship between Servant Leadership and Quality of Worklife in the customer service frontline context. While there is a broad base of literature available on servant leadership that focuses on the senior or executive level of leadership, Van Dierendonck and Nuijten (2011) have argued that it is also relevant at the middle level of management and have validated an eight dimensional measure of servant leadership that is suitable for this management level. The Van Laar, Edwards and Easton (2007) Quality of Worklife model is also argued to be an appropriate model and measure of the Quality of Worklife construct, due to the robustness of the instrument design and the appropriateness of its underlying theory to the context of this research. Research has shown that leadership can have a significant relationship with Quality of Worklife. Moreover, a review of the literature on servant leadership reveals that trust, satisfaction, general well-being, and commitment to their jobs increases when employees are exposed to leadership behaviours associated with servant leadership. There is however, no evidence in the literature of any investigation of the relationship between Servant Leadership and Quality of Worklife, or of research investigating the partial mediating effects of Trust between these two constructs. Research was conducted to test this relationship. A survey questionnaire was administered amongst a sample of 555 Contact Centre agents, who were employed in eight different organisations. Confirmatory factor analysis procedures were conducted in STATA (V15.0), to test and validate the factor structure of Servant Leadership and Quality of Worklife models. The research also produced a Servant Leadership, Trust and Quality of Worklife structural equation model that supported the hypotheses of the relationships between the constructs. Mediation analysis confirmed Trust’s role as a mediator between Servant Leadership and Quality of Worklife. The structural equation model confirmed that synergies between Servant Leadership, Trust and Quality of Worklife exist, and that Trust partially mediates the relationship between Servant Leadership and Quality of Worklife. It is therefore argued that an increase in Servant Leadership behaviour by the manager or supervisor of frontline staff has a positive association with increases of Trust, as well as positive associations with Quality of Worklife experienced by employees in the frontline context. Moreover, it is also posited that the relationship between Servant Leadership and Quality of Worklife is partially mediated by Trust of the supervisor. The implications of these results are discussed, and recommendations made for management practice and further research.
- Full Text:
- Date Issued: 2018
- Authors: Bedser, Mark Bernard
- Date: 2018
- Subjects: Call center agents Servant leadership Customer Service -- Quality control Employee morale Job satisfaction Quality of work life
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62144 , vital:28132
- Description: Contact Centre agents operate in closely monitored and highly controlled environments and their work consists of solving service requests or assisting customers with information on products or services. Consequently their work involves a great deal of emotional labour and stress. It is not surprising then, that the working environment of the Contact Centre is reported to have a negative impact on the levels of Quality of Worklife of Contact Centre agents, and that in the Contact Centre context, it is likely that low levels of Quality of Worklife exist. It is argued that it is important for organisations to be particularly aware of the Quality of Worklife perceptions of their employees should they want to address Quality of Worklife levels and benefit from the positive consequences of higher levels of the construct. Numerous variables are reported to play either an antecedent, moderating, mediating, or consequential role in relation to the Quality of Worklife construct. A systems model of Quality of Worklife is developed, which illustrates the inter-relationships of these variables and how they affect and are affected by the Quality of Worklife construct. It is argued that leadership is an important antecedent to Quality of Worklife, and this is the antecedent of interest in this study. It is proposed that it is not just any leadership that will contribute to an improved Quality of Worklife, particularly within a challenging context such as the Contact Centre environment. Rather, it is suggested that certain qualities of leaders will have a greater influence on Quality of Worklife. For example, leaders who focus on relationships and are caring - characteristics associated with servant leaders - are deemed more suitable for the Contact Centre context. The research also proposes that there are close associations between Servant Leadership and Trust, which in turn has the potential to affect Quality of Worklife positively. It is argued, therefore, that Trust mediates the relationship between Servant Leadership and Quality of Worklife in the customer service frontline context. While there is a broad base of literature available on servant leadership that focuses on the senior or executive level of leadership, Van Dierendonck and Nuijten (2011) have argued that it is also relevant at the middle level of management and have validated an eight dimensional measure of servant leadership that is suitable for this management level. The Van Laar, Edwards and Easton (2007) Quality of Worklife model is also argued to be an appropriate model and measure of the Quality of Worklife construct, due to the robustness of the instrument design and the appropriateness of its underlying theory to the context of this research. Research has shown that leadership can have a significant relationship with Quality of Worklife. Moreover, a review of the literature on servant leadership reveals that trust, satisfaction, general well-being, and commitment to their jobs increases when employees are exposed to leadership behaviours associated with servant leadership. There is however, no evidence in the literature of any investigation of the relationship between Servant Leadership and Quality of Worklife, or of research investigating the partial mediating effects of Trust between these two constructs. Research was conducted to test this relationship. A survey questionnaire was administered amongst a sample of 555 Contact Centre agents, who were employed in eight different organisations. Confirmatory factor analysis procedures were conducted in STATA (V15.0), to test and validate the factor structure of Servant Leadership and Quality of Worklife models. The research also produced a Servant Leadership, Trust and Quality of Worklife structural equation model that supported the hypotheses of the relationships between the constructs. Mediation analysis confirmed Trust’s role as a mediator between Servant Leadership and Quality of Worklife. The structural equation model confirmed that synergies between Servant Leadership, Trust and Quality of Worklife exist, and that Trust partially mediates the relationship between Servant Leadership and Quality of Worklife. It is therefore argued that an increase in Servant Leadership behaviour by the manager or supervisor of frontline staff has a positive association with increases of Trust, as well as positive associations with Quality of Worklife experienced by employees in the frontline context. Moreover, it is also posited that the relationship between Servant Leadership and Quality of Worklife is partially mediated by Trust of the supervisor. The implications of these results are discussed, and recommendations made for management practice and further research.
- Full Text:
- Date Issued: 2018
Stewardship and collaboration in multifunctional landscapes: a transdisciplinary enquiry
- Authors: Cockburn, Jessica Jane
- Date: 2018
- Subjects: Environmental management -- South Africa , Sustainable development -- South Africa , Ecosystem management -- South Africa , Social ecology -- South Africa , Interdisciplinary research
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61267 , vital:27998
- Description: Social-ecological sustainability challenges, from the local to the global level, are of increasing concern. Stewardship has been proposed as a means of dealing with these challenges, but how can it be achieved in practice? In South Africa, the concept is put into practice by practitioners working with local stewards to facilitate more sustainable and equitable management of ecosystem services across landscapes. This landscape approach requires collaboration between multiple stakeholders, as social-ecological processes function beyond the boundaries of individual farms or villages. The aim of this research was to investigate the practice of stewardship and collaboration in multifunctional landscapes in South Africa through a transdisciplinary enquiry. This was achieved using a methodological framework based on critical complexity, transdisciplinarity, and critical realism. This framework was applied through an inductive, mixed methods research design which involved stewardship practitioners, stewards, and other stakeholders in the research. Practitioners' understandings of the stewardship concept vary, yet they coalesce around the idea of responsible use and care of nature. Accordingly, the primary role of stewards is to interact with nature responsibly and carefully, balancing the use of ecosystem services for their own benefit with broader social- ecological interests and needs. Although the biodiversity stewardship tool dominates stewardship practice in South Africa, more integrated social-ecological initiatives are also emerging, often hand-in-hand with this approach. Practitioners working in these initiatives face multiple interacting and mutually reinforcing enablers and barriers that facilitate or hinder collaboration for stewardship. Individual and social-relational enablers are pivotal to long-term sustainability of initiatives, whilst deep-seated inequalities and mistrust are significant barriers to collaboration. Despite such challenges, practitioners are succeeding in fostering collaboration by operating as hubs in the landscape. They are actively building new relationships and networks among diverse stakeholders to address shared sustainability challenges. This results in a patchwork of collaborative stewardship activity across the landscape, suggesting that stewardship and collaboration are fundamentally relational processes and that pluralistic approaches to sustainability are needed in multifunctional landscapes. Moreover, by re-focusing stewardship on stewards, practitioners are finding innovative ways to enable farmers to appreciate and practice stewardship, addressing the conflict between agriculture and conservation. Drawing on these findings, a critical realist analysis revealed underlying generative mechanisms that help to explain the challenges encountered in collaborative efforts toward stewardship. These mechanisms included, amongst others: individual stewards' values, societal constraints on the ability of stewards to express care, conflict between agriculture and conservation due to dominant agricultural approaches and neoliberal economic policies, and the divided and unequal nature of South African society. Operationalising transdisciplinary research enabled meaningful engagement with practitioner partners, allowing for novel insights and unexpected findings to emerge from practice-based knowledge. Putting transdisciplinarity into practice revealed the dynamic and multi-faceted role that researchers can play in transdisciplinary research, highlighting the importance of relational knowledge and competencies. Existing support systems and incentives within universities need to be re-configured to enable postgraduate students to conduct engaged science in service of society. , Kuyanda ukuxhalatyiswa yimiceli mngeni yobudlewlane obuhlala buhleli bezentlalo nendalo, ekuhlaleni nakwihlabathi. Kuphakanyiswe umbono wobugosa-bumeli (ubuphathi bendalo, stewardship) ukuze kuhlangatyezwane nale miceli mngeni, kodwa iza kwenziwa njani le nto? EMzantsi Afrika le ngcamango iye yabekwa entsebenzweni ngabo banezakhono no bugcisa besebenza namagosa-bameli asekuhlaleni, benceda ekulawulweni ngendlela ehlala ihleli nelinganayo iinkonzo zobudlelwane nendalo kuyo yonke imihlaba. Le ndlela yokusebenzisa le mihlaba ifuna intsebenziswano phakathi kwabo bonke ababandakanyekayo, njengoko ubudlelwane bentlalo nendalo busebenza ngaphaya kwemida yomfama ngamnye okanye iilali. Injongo yoluhlolisiso ibikukuphanda ngoqheliselo lobugosa-bumeli nentsebenziswano yeemihlaba esebenza ngendlela ezininzi eMzantsi Afrika kubuzwa kumasebe olwazi ohlukeneyo olwazi(transdisciplinarity). Oku kwathi kwaphunyezwa ngenkqubo ehlola izinto ezahlukahlukeneyo kwimigangatho eyahlukeneyo, isekelwe kwingcamango enzulu kunoko kubonakala kuqondakalayo, kumasebe olwazi ohlukeneyo, nakulwazi lwesayensi nentlalo. Le nkqubo yenziwa kusetyenziswa inkqubo yokuqokelela ulwazi luze luhlalutywe, iintlobo ezahlukeneyo zokwenza uhlolisiso, ezazibandakandakanya abanezakhono zobugosa-bumeli, amagosa-bameli nabanye ababandakanyekileyo kolu hlolisiso. Ingcamango zabanezakhono zobubugosa-bumeli ziyohluka, kanti iingcamango zinye ngokuphathelele ukusetyenziswa nokukhathelela indalo yemvelo. Phofu ke, indima esisiseko yamagosa-bameli kukuphembelelana ngokufanelekileyo nangenkathalo nendalo, bethelekisa ukusebenzisa iinkonzo zobudlelwane nendalo ukuze zincede bona, kunye nomdla neemfuno eziphangaleleyo zobudlelwane bendalo nentlalo. Nakubeni isixhobo Sobugosa-Bumeli Bendalo Eyahlukeneyo Yezityalo Nezilwanyana (Biodiversity Stewardship) isesona sitshotsha phambili kuqheliselo lobugosa-bumeli eMzantsi Afrika, zikhona nezinye izixhobo ezivelayo eziqukwayo kwiphulo lobudlelwane bendalo nentlalo, ezisoloko zisebenza kakuhle neli lokuqala. Abanezakhono nabasebenza kula maphulo bajamelene neendidi zokuphembelelana, iingxaki ezahlukeneyo, izisombululo nezithinteli ezinceda okanye zonakalise intebenziswano yobugosa-bumeli. Isisombululo ngasinye nezo zayanyaniswa nentlalo zibaluleke gqitha kumaphulo azakuhlala ehleli, nakubeni ukungalingani okuzinze nzulu nokungathembani iyimiqobo ebelulekileyo kwintsebenziswano. Nangona ikhona le micelimngeni, abanezakhono bayaphumelela ekukhuliseni intsebenziswano ngokuthi basebenze kwiindawo ezithile kwimihlaba. Bakha unxulumano olutsha noqhagamishelwano nababandakanyekileyo ngokwahluka kwabo ukuze kusingathwe nemiceli mngeni yokugcina ubudlelwane bendalo nentlalo buhlale buhleli. Oku kuye kwaphumela kwintsebenziswano yobugosa-bumeli ethe yakho pha na pha kule mihlaba, nto leyo ebonisa ukuba ubugosa- bumeli nentsebenziswano ngokusisiseko yinkqubo enxulumeneyo, kwaye iindlela ezininzi zokwenza ubudlelwane bendalo nentlalo buhlale buhleli ziyimfuneko kwimihlaba ekwenziwa izinto ezininzi kuyo. Ngapha koko, ngokuthi kuphindwe kunikelwe ingqalelo kubugosa-bumeli isiya kumagosa bameli, abanezakhono bafumana iindlela ezintsha zokunceda amafama axabise aze aqhelisele ubugosa-bumeli, ngolu hlobo kusingathwa ingxabano phakathi kwezolimo nolondolozo lwendalo. Xa sifunda koku, ukucamngca nzulu ngako kutyhile enye indlela eye yanceda ekucaciseni imiceli mngeni ekuhlangatyezwane nayo kwimigudu yentsebenziswano yobugosa-bumeli. Ezi ndlela zibandakanya, phakathi kwezinye: indlela aziphatha ngayo amagosa-bameli, iingcinezelo yabahlali ekubeni amagosa-bameli abonakalise inkathalo, ukungavisisani phakathi kwezolimo nolondolozo lwendalo ngenxa yendlela ezongamelayo nezisetyenziswayo zolimo, nemigaqo-nkqubo yezoqoqosho elawulwa bucala, nokwahlukana, ukungalingani kwabantu baseMzantsi Afrika. Ukusebenzisa uhlolisiso lwamasebe olwazi ohlukeneyo kubangele ukufuthelana okunentsingiselo namaqabane abo banezakhono, oku kuvulele iingcamango ezinzulu nokufumana izinto ebezingalindelekanga kulwazi olusekelwe kuqheliselo. Ukubeka ulwazi lwamasebe ahlukeneyo entsebenzweni kutyhile iindima ezahlukeneyo okanye ezininzi ezidlalwa ngabahlolisisi kuhlolisiso lolwazi lwamasebe ohlukeneyo, kubalaseliswa ukubaluleka kolwazi olunxulunyaniswayo nozimiselo. Iinkqubo zenkxaso nezinye izinto ezincedayo ezikhoyo kwiyunivesiti kufuneka ziphinde zakhiwe ukuze zincede abafundi abenza uhlolisiso balwenze benomfutho wesayensi enceda abahlali.
- Full Text:
- Date Issued: 2018
- Authors: Cockburn, Jessica Jane
- Date: 2018
- Subjects: Environmental management -- South Africa , Sustainable development -- South Africa , Ecosystem management -- South Africa , Social ecology -- South Africa , Interdisciplinary research
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61267 , vital:27998
- Description: Social-ecological sustainability challenges, from the local to the global level, are of increasing concern. Stewardship has been proposed as a means of dealing with these challenges, but how can it be achieved in practice? In South Africa, the concept is put into practice by practitioners working with local stewards to facilitate more sustainable and equitable management of ecosystem services across landscapes. This landscape approach requires collaboration between multiple stakeholders, as social-ecological processes function beyond the boundaries of individual farms or villages. The aim of this research was to investigate the practice of stewardship and collaboration in multifunctional landscapes in South Africa through a transdisciplinary enquiry. This was achieved using a methodological framework based on critical complexity, transdisciplinarity, and critical realism. This framework was applied through an inductive, mixed methods research design which involved stewardship practitioners, stewards, and other stakeholders in the research. Practitioners' understandings of the stewardship concept vary, yet they coalesce around the idea of responsible use and care of nature. Accordingly, the primary role of stewards is to interact with nature responsibly and carefully, balancing the use of ecosystem services for their own benefit with broader social- ecological interests and needs. Although the biodiversity stewardship tool dominates stewardship practice in South Africa, more integrated social-ecological initiatives are also emerging, often hand-in-hand with this approach. Practitioners working in these initiatives face multiple interacting and mutually reinforcing enablers and barriers that facilitate or hinder collaboration for stewardship. Individual and social-relational enablers are pivotal to long-term sustainability of initiatives, whilst deep-seated inequalities and mistrust are significant barriers to collaboration. Despite such challenges, practitioners are succeeding in fostering collaboration by operating as hubs in the landscape. They are actively building new relationships and networks among diverse stakeholders to address shared sustainability challenges. This results in a patchwork of collaborative stewardship activity across the landscape, suggesting that stewardship and collaboration are fundamentally relational processes and that pluralistic approaches to sustainability are needed in multifunctional landscapes. Moreover, by re-focusing stewardship on stewards, practitioners are finding innovative ways to enable farmers to appreciate and practice stewardship, addressing the conflict between agriculture and conservation. Drawing on these findings, a critical realist analysis revealed underlying generative mechanisms that help to explain the challenges encountered in collaborative efforts toward stewardship. These mechanisms included, amongst others: individual stewards' values, societal constraints on the ability of stewards to express care, conflict between agriculture and conservation due to dominant agricultural approaches and neoliberal economic policies, and the divided and unequal nature of South African society. Operationalising transdisciplinary research enabled meaningful engagement with practitioner partners, allowing for novel insights and unexpected findings to emerge from practice-based knowledge. Putting transdisciplinarity into practice revealed the dynamic and multi-faceted role that researchers can play in transdisciplinary research, highlighting the importance of relational knowledge and competencies. Existing support systems and incentives within universities need to be re-configured to enable postgraduate students to conduct engaged science in service of society. , Kuyanda ukuxhalatyiswa yimiceli mngeni yobudlewlane obuhlala buhleli bezentlalo nendalo, ekuhlaleni nakwihlabathi. Kuphakanyiswe umbono wobugosa-bumeli (ubuphathi bendalo, stewardship) ukuze kuhlangatyezwane nale miceli mngeni, kodwa iza kwenziwa njani le nto? EMzantsi Afrika le ngcamango iye yabekwa entsebenzweni ngabo banezakhono no bugcisa besebenza namagosa-bameli asekuhlaleni, benceda ekulawulweni ngendlela ehlala ihleli nelinganayo iinkonzo zobudlelwane nendalo kuyo yonke imihlaba. Le ndlela yokusebenzisa le mihlaba ifuna intsebenziswano phakathi kwabo bonke ababandakanyekayo, njengoko ubudlelwane bentlalo nendalo busebenza ngaphaya kwemida yomfama ngamnye okanye iilali. Injongo yoluhlolisiso ibikukuphanda ngoqheliselo lobugosa-bumeli nentsebenziswano yeemihlaba esebenza ngendlela ezininzi eMzantsi Afrika kubuzwa kumasebe olwazi ohlukeneyo olwazi(transdisciplinarity). Oku kwathi kwaphunyezwa ngenkqubo ehlola izinto ezahlukahlukeneyo kwimigangatho eyahlukeneyo, isekelwe kwingcamango enzulu kunoko kubonakala kuqondakalayo, kumasebe olwazi ohlukeneyo, nakulwazi lwesayensi nentlalo. Le nkqubo yenziwa kusetyenziswa inkqubo yokuqokelela ulwazi luze luhlalutywe, iintlobo ezahlukeneyo zokwenza uhlolisiso, ezazibandakandakanya abanezakhono zobugosa-bumeli, amagosa-bameli nabanye ababandakanyekileyo kolu hlolisiso. Ingcamango zabanezakhono zobubugosa-bumeli ziyohluka, kanti iingcamango zinye ngokuphathelele ukusetyenziswa nokukhathelela indalo yemvelo. Phofu ke, indima esisiseko yamagosa-bameli kukuphembelelana ngokufanelekileyo nangenkathalo nendalo, bethelekisa ukusebenzisa iinkonzo zobudlelwane nendalo ukuze zincede bona, kunye nomdla neemfuno eziphangaleleyo zobudlelwane bendalo nentlalo. Nakubeni isixhobo Sobugosa-Bumeli Bendalo Eyahlukeneyo Yezityalo Nezilwanyana (Biodiversity Stewardship) isesona sitshotsha phambili kuqheliselo lobugosa-bumeli eMzantsi Afrika, zikhona nezinye izixhobo ezivelayo eziqukwayo kwiphulo lobudlelwane bendalo nentlalo, ezisoloko zisebenza kakuhle neli lokuqala. Abanezakhono nabasebenza kula maphulo bajamelene neendidi zokuphembelelana, iingxaki ezahlukeneyo, izisombululo nezithinteli ezinceda okanye zonakalise intebenziswano yobugosa-bumeli. Isisombululo ngasinye nezo zayanyaniswa nentlalo zibaluleke gqitha kumaphulo azakuhlala ehleli, nakubeni ukungalingani okuzinze nzulu nokungathembani iyimiqobo ebelulekileyo kwintsebenziswano. Nangona ikhona le micelimngeni, abanezakhono bayaphumelela ekukhuliseni intsebenziswano ngokuthi basebenze kwiindawo ezithile kwimihlaba. Bakha unxulumano olutsha noqhagamishelwano nababandakanyekileyo ngokwahluka kwabo ukuze kusingathwe nemiceli mngeni yokugcina ubudlelwane bendalo nentlalo buhlale buhleli. Oku kuye kwaphumela kwintsebenziswano yobugosa-bumeli ethe yakho pha na pha kule mihlaba, nto leyo ebonisa ukuba ubugosa- bumeli nentsebenziswano ngokusisiseko yinkqubo enxulumeneyo, kwaye iindlela ezininzi zokwenza ubudlelwane bendalo nentlalo buhlale buhleli ziyimfuneko kwimihlaba ekwenziwa izinto ezininzi kuyo. Ngapha koko, ngokuthi kuphindwe kunikelwe ingqalelo kubugosa-bumeli isiya kumagosa bameli, abanezakhono bafumana iindlela ezintsha zokunceda amafama axabise aze aqhelisele ubugosa-bumeli, ngolu hlobo kusingathwa ingxabano phakathi kwezolimo nolondolozo lwendalo. Xa sifunda koku, ukucamngca nzulu ngako kutyhile enye indlela eye yanceda ekucaciseni imiceli mngeni ekuhlangatyezwane nayo kwimigudu yentsebenziswano yobugosa-bumeli. Ezi ndlela zibandakanya, phakathi kwezinye: indlela aziphatha ngayo amagosa-bameli, iingcinezelo yabahlali ekubeni amagosa-bameli abonakalise inkathalo, ukungavisisani phakathi kwezolimo nolondolozo lwendalo ngenxa yendlela ezongamelayo nezisetyenziswayo zolimo, nemigaqo-nkqubo yezoqoqosho elawulwa bucala, nokwahlukana, ukungalingani kwabantu baseMzantsi Afrika. Ukusebenzisa uhlolisiso lwamasebe olwazi ohlukeneyo kubangele ukufuthelana okunentsingiselo namaqabane abo banezakhono, oku kuvulele iingcamango ezinzulu nokufumana izinto ebezingalindelekanga kulwazi olusekelwe kuqheliselo. Ukubeka ulwazi lwamasebe ahlukeneyo entsebenzweni kutyhile iindima ezahlukeneyo okanye ezininzi ezidlalwa ngabahlolisisi kuhlolisiso lolwazi lwamasebe ohlukeneyo, kubalaseliswa ukubaluleka kolwazi olunxulunyaniswayo nozimiselo. Iinkqubo zenkxaso nezinye izinto ezincedayo ezikhoyo kwiyunivesiti kufuneka ziphinde zakhiwe ukuze zincede abafundi abenza uhlolisiso balwenze benomfutho wesayensi enceda abahlali.
- Full Text:
- Date Issued: 2018
Strength and conditioning of adolescent male cricket players
- Authors: Pote, Lee
- Date: 2018
- Subjects: Cricket South Africa , Cricket injuries South Africa , Cricket Physiological aspects , Cricket Coaching South Africa , Physical fitness for youth South Africa , CricFit
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63933 , vital:28508
- Description: Background: Modern day cricketers are faced with longer, more strenuous seasons which are more physically demanding than the traditional forms of the game. Due to these increased physical demands, players are more prone to both overuse injuries, particularly of the lower back (bowlers) and lower limbs (batsmen), as well as acute, impact injuries (fielders/wicket keepers). The increase in injury risk is of particular concern at younger levels as research has shown that adolescents are at a higher risk for injury than their adult counterparts. Therefore, there is a need for strength and conditioning programs that reduce the risk of injury and improve performance at this level. However, of the programs that are available, most are not multi-factorial in nature and are aimed at elite cricketers. This is of concern in low-to-middle income countries such as South Africa, where players often do not have access to facilities or equipment and thus need to be exposed to low-cost, no-cost training programs. Furthermore, most information is anecdotal and there is a distinct lack of injury prevention programs at an adolescent level. Objective: The purpose of this thesis was to investigate the strength and conditioning practices of adolescent cricket players, particularly from a South African context, where there is a distinct lack of resources. This was through the completion of three phases; firstly, a literature review was completed to determine the information currently available on injury prevention strategies in cricket. The review also examined the injury statistics of five major playing cricket nations. Secondly, a survey was conducted to determine the current strength and conditioning practices of schoolboy and university coaches in South Africa. Lastly, a novel intervention program (CricFit) was designed and implemented within an adolescent population. The main purpose of the intervention was to determine whether players’ physical fitness parameters improved over time and whether the risk of injury was reduced. Methods: For phase one of the thesis (review paper), a search of the different scientific databases was undertaken to determine the nature and incidence of injuries in cricket activity as well as well as current strength and conditioning practices in place to reduce these injuries. These injury statistics and prevention programs where then reviewed. For the survey based research, an online questionnaire, adapted from previous strength and conditioning studies, was sent to 38 school boy and 12 university teams that participated in the top competitions in South Africa. In addition to the previous questionnaires, cricket specific practices and injury statistic questions were added to the survey. The survey consisted of three sections: a general, cricket specific and injury and injury prevention section. The survey also allowed coaches at both university and school levels to describe their practices and ideas in order to understand their basic knowledge of scientifically-based principles of strength and conditioning. Thus coaches were encouraged to explain what conditioning practices they implemented through a number of open ended questions which were then analysed for minor and major themes. The focus of the intervention program was to improve general physical fitness for cricket players. The study was a pre- and post-test design where twenty eight schoolboy cricketers (aged 15-19 years) were allocated to a control (n=14) or experimental (n=14) group during the cricket pre-season period. Both groups performed traditional net and field based training over a four week period (one net and one field based session), with the experimental group performing an additional two, 35-45 minute, conditioning sessions per week (“CricFit” intervention program). The intervention consisted of exercises that centred on the movement demands associated with the sport of cricket as well as injury prevention exercises (specifically Nordic lowers and core strength). Prior to and post the four week intervention period, responses were measured using a test battery that was designed to replicate the demands of cricket activity. Results: The results indicate on overall thesis summary. The literature view showed that there is a limited amount of injury prevention programs available for adolescent cricket players. It was also confirmed that for both adolescent and adult players, fast bowlers (lower back), followed by batsmen (lower limbs) and then fielders (impact) are the most prone to injuries. The survey showed that schools and universities in South Africa do conduct some form of conditioning, workload monitoring and injury prevention exercises; however the incorrect practices are being administered when considering the movement demands and most common injuries in cricket. It was also shown that most coaches did not have the adequate qualifications and experience to implement acceptable strength and conditioning programs. For the intervention study, both the control and experimental groups showed significant (p<0.05) improvements in most responses, but the changes for the experimental group were greater than those shown in the control group. Furthermore, significant (p<0.05) changes were shown between the two groups (control vs. experimental) for percentage body fat (12 vs. 11%), sit and reach flexibility (40.79 vs. 80.50mm), plank time (105.36 vs. 185.29s), 20 m sprint time (3.27 vs. 2.84s), push ups (34 vs. 41) and 25 m shuttle distance (699.18 vs. 746.79m). Conclusion: Coaches need to be educated and trained to implement the correct strength and conditioning practices at an adolescent level as well as to better understand the link between the movement demands and principles of testing and training. An improved education process may be needed to improve the quality as well as the qualifications of strength and conditioning coaches. If coaches and trainers are educated properly, then the “CricFit” intervention program may be used to improve cricket specific fitness throughout the pre-season period. The “CricFit” programme is useful in countries such as South Africa, where often players do not have access to coaches and facilities and thus can be implemented easily with minimal cost.
- Full Text:
- Date Issued: 2018
- Authors: Pote, Lee
- Date: 2018
- Subjects: Cricket South Africa , Cricket injuries South Africa , Cricket Physiological aspects , Cricket Coaching South Africa , Physical fitness for youth South Africa , CricFit
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63933 , vital:28508
- Description: Background: Modern day cricketers are faced with longer, more strenuous seasons which are more physically demanding than the traditional forms of the game. Due to these increased physical demands, players are more prone to both overuse injuries, particularly of the lower back (bowlers) and lower limbs (batsmen), as well as acute, impact injuries (fielders/wicket keepers). The increase in injury risk is of particular concern at younger levels as research has shown that adolescents are at a higher risk for injury than their adult counterparts. Therefore, there is a need for strength and conditioning programs that reduce the risk of injury and improve performance at this level. However, of the programs that are available, most are not multi-factorial in nature and are aimed at elite cricketers. This is of concern in low-to-middle income countries such as South Africa, where players often do not have access to facilities or equipment and thus need to be exposed to low-cost, no-cost training programs. Furthermore, most information is anecdotal and there is a distinct lack of injury prevention programs at an adolescent level. Objective: The purpose of this thesis was to investigate the strength and conditioning practices of adolescent cricket players, particularly from a South African context, where there is a distinct lack of resources. This was through the completion of three phases; firstly, a literature review was completed to determine the information currently available on injury prevention strategies in cricket. The review also examined the injury statistics of five major playing cricket nations. Secondly, a survey was conducted to determine the current strength and conditioning practices of schoolboy and university coaches in South Africa. Lastly, a novel intervention program (CricFit) was designed and implemented within an adolescent population. The main purpose of the intervention was to determine whether players’ physical fitness parameters improved over time and whether the risk of injury was reduced. Methods: For phase one of the thesis (review paper), a search of the different scientific databases was undertaken to determine the nature and incidence of injuries in cricket activity as well as well as current strength and conditioning practices in place to reduce these injuries. These injury statistics and prevention programs where then reviewed. For the survey based research, an online questionnaire, adapted from previous strength and conditioning studies, was sent to 38 school boy and 12 university teams that participated in the top competitions in South Africa. In addition to the previous questionnaires, cricket specific practices and injury statistic questions were added to the survey. The survey consisted of three sections: a general, cricket specific and injury and injury prevention section. The survey also allowed coaches at both university and school levels to describe their practices and ideas in order to understand their basic knowledge of scientifically-based principles of strength and conditioning. Thus coaches were encouraged to explain what conditioning practices they implemented through a number of open ended questions which were then analysed for minor and major themes. The focus of the intervention program was to improve general physical fitness for cricket players. The study was a pre- and post-test design where twenty eight schoolboy cricketers (aged 15-19 years) were allocated to a control (n=14) or experimental (n=14) group during the cricket pre-season period. Both groups performed traditional net and field based training over a four week period (one net and one field based session), with the experimental group performing an additional two, 35-45 minute, conditioning sessions per week (“CricFit” intervention program). The intervention consisted of exercises that centred on the movement demands associated with the sport of cricket as well as injury prevention exercises (specifically Nordic lowers and core strength). Prior to and post the four week intervention period, responses were measured using a test battery that was designed to replicate the demands of cricket activity. Results: The results indicate on overall thesis summary. The literature view showed that there is a limited amount of injury prevention programs available for adolescent cricket players. It was also confirmed that for both adolescent and adult players, fast bowlers (lower back), followed by batsmen (lower limbs) and then fielders (impact) are the most prone to injuries. The survey showed that schools and universities in South Africa do conduct some form of conditioning, workload monitoring and injury prevention exercises; however the incorrect practices are being administered when considering the movement demands and most common injuries in cricket. It was also shown that most coaches did not have the adequate qualifications and experience to implement acceptable strength and conditioning programs. For the intervention study, both the control and experimental groups showed significant (p<0.05) improvements in most responses, but the changes for the experimental group were greater than those shown in the control group. Furthermore, significant (p<0.05) changes were shown between the two groups (control vs. experimental) for percentage body fat (12 vs. 11%), sit and reach flexibility (40.79 vs. 80.50mm), plank time (105.36 vs. 185.29s), 20 m sprint time (3.27 vs. 2.84s), push ups (34 vs. 41) and 25 m shuttle distance (699.18 vs. 746.79m). Conclusion: Coaches need to be educated and trained to implement the correct strength and conditioning practices at an adolescent level as well as to better understand the link between the movement demands and principles of testing and training. An improved education process may be needed to improve the quality as well as the qualifications of strength and conditioning coaches. If coaches and trainers are educated properly, then the “CricFit” intervention program may be used to improve cricket specific fitness throughout the pre-season period. The “CricFit” programme is useful in countries such as South Africa, where often players do not have access to coaches and facilities and thus can be implemented easily with minimal cost.
- Full Text:
- Date Issued: 2018
Students’ perceptions towards the influences of social media on students’ academic engagement at a tertiary institution: a case study on the use of Facebook and Twitter at Rhodes University
- Authors: Moongela, Harry
- Date: 2018
- Subjects: Facebook (Firm) , Twitter (Firm) , Social media in education -- South Africa -- Makhanda , Motivation in education -- South Africa -- Makhanda , Education, Higher -- Effect of technological innovations on -- South Africa -- Makhanda , Rhodes University
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60730 , vital:27823
- Description: The use of social media has become an integral part of student’s academic lives and has had an impact on students’ academic engagement in tertiary institutions. Subsequently, researchers have shown an interest in investigating the impact of social media on students’ academic engagement. Despite the fact that researcher have shown interest, there still remains a limited number of studies that have discussed the effects of social media on students’ academic engagement, particularly within a South African context. Also, studies that have been carried have revealed limited and mixed findings. This study then aims to further investigate whether the exposure of students to social media has an effect on their academic engagement and how tertiary institutions together with students can use social media to improve students’ academic engagement. A qualitative research method using an interpretive (inductive) approach is carried out to find out students’ perceptions towards the use of social media and its influence on students’ academic engagement. The study then reveals recommendations from students’ perceptions on the effective ways of using social media to benefit students’ academic engagement in tertiary institutions.
- Full Text:
- Date Issued: 2018
- Authors: Moongela, Harry
- Date: 2018
- Subjects: Facebook (Firm) , Twitter (Firm) , Social media in education -- South Africa -- Makhanda , Motivation in education -- South Africa -- Makhanda , Education, Higher -- Effect of technological innovations on -- South Africa -- Makhanda , Rhodes University
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60730 , vital:27823
- Description: The use of social media has become an integral part of student’s academic lives and has had an impact on students’ academic engagement in tertiary institutions. Subsequently, researchers have shown an interest in investigating the impact of social media on students’ academic engagement. Despite the fact that researcher have shown interest, there still remains a limited number of studies that have discussed the effects of social media on students’ academic engagement, particularly within a South African context. Also, studies that have been carried have revealed limited and mixed findings. This study then aims to further investigate whether the exposure of students to social media has an effect on their academic engagement and how tertiary institutions together with students can use social media to improve students’ academic engagement. A qualitative research method using an interpretive (inductive) approach is carried out to find out students’ perceptions towards the use of social media and its influence on students’ academic engagement. The study then reveals recommendations from students’ perceptions on the effective ways of using social media to benefit students’ academic engagement in tertiary institutions.
- Full Text:
- Date Issued: 2018
Studies in leaf domatia-mite mutualism in South Africa
- Authors: Situngu, Sivuyisiwe
- Date: 2018
- Subjects: Insect-plant relationships , Mites , Mutualism (Biology) , Biological pest control agents
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63334 , vital:28394
- Description: Plants have various traits which allow them to cope and resist their enemies including both insects and fungi . In some cases such traits allow plants to build mutualistic relationships with natural enemies of plant pests. This is the case in many dicotyledonous plants which produce leaf domatia. Leaf domatia are plant cavities usually found in the axils of major veins in the abaxial side of leaves. They are usually associated with mites and often mediate mutualistic relationships with predacious mites. Mites use leaf domatia primarily for shelter, to reproduce, and to develop. In turn, plants benefit from having predaceous mites on their leaves, because mites act as plant “bodyguards” and offer defence against pathogens and small arthropod herbivores. This phenomenon has been well documented all over the world, but Africa remains disproportionally understudied. The aim of this study was to fill the gap that exists in our knowledge of the extent of the distribution of leaf domatia-mite mutualisms and generate a better understanding of the diversity of mites found within leaf domatia from an African perspective. This was done by surveying plant species that bear leaf domatia from different vegetation types in South Africa. The plants with leaf domatia were examined for the presence of mites in order to determine patterns of mite abundance and diversity and, in so doing, address the following questions: • Does each tree species host have a specific mite or mite assemblage? • Do some mites prefer certain types of leaf domatia? • Do mites prefer a specific place in the tree canopy and does the microclimate in the tree canopy affect the distribution of mites? • Do different vegetation sites and types differ in their mite diversity and species composition? • Does mite abundance and diversity vary with seasons? Do coffee plantations have a different suite of mites than the adjacent forest? The anatomical structures of leaf domatia from six selected plant species(Coffea arabica, Gardenia thunbergia, Rothmannia capensis, Rothmannia globosa (Rubiaceae), Ocotea bullata (Lauraceae) and Tecoma capensis (Bignoniaceae) with different types of leaf domatia were also studied. The results from this study suggested that the key futures which distinguish domatia are the presence of an extra layer of tissue in the lower epidermis, a thick cuticle, cuticular folds, the presence of trichomes and an invagination. This study provides a better understating of the structure of leaf domatia. Leaf domatia bearing plants are widely distributed in South Africa, and species and vegetation-specific associations were assessed. Over 250 plant specimens with leaf domatia were collected and examined and more than 60 different mite species were found in association with the sampled plant species. The majority of mites found within the domatia of these tree species were predaceous and included mites from Stigmatidae, Tydeidae and Phytoseiidae. Furthermore, 15 new species were collected, suggesting that mites are understudied in South Africa. This study showed that the different vegetation types sampled did not differ markedly in terms of their mite biota and that similar mites were found across the region, and the association between leaf domatia and mites was found to be opportunistic and that mites had no preference for any particular domatia types. No host specificity relationship was observed between plants and mites. The assessment of mites associated with Coffea arabica showed that indigenous mites are able to colonise and establish a beneficial mutualism on exotic species. This is important as it ascertains that economically important plants that are cultivated outside their area of natural distribution can still benefit from this mutualism. This study also found that mite abundance and diversity in plants with leaf domatia were influenced by factors such as temperature, relative humidity and rainfall. Mite communities found in association with domatia changed as the year progressed and over the seasons. The seasonal fluctuations varied between the sampled plant species. In addition, this study found that mites were sensitive to extreme environmental conditions, and thus, mites preferred leaves found in the lower parts of the tree canopy and avoided exposed leaves. This study provides a better understanding of the distribution of domatia bearing plants in South Africa and their associated mites and contributes to our knowledge of the biodiversity of mites in the region. Furthermore, this study also adds to our understanding of the leaf domatia - mite mutualism in Africa. The applied example looking at the plant-mite mutualism in Coffea arabica highlights the importance of this mutualism in commercial plants.
- Full Text:
- Date Issued: 2018
- Authors: Situngu, Sivuyisiwe
- Date: 2018
- Subjects: Insect-plant relationships , Mites , Mutualism (Biology) , Biological pest control agents
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63334 , vital:28394
- Description: Plants have various traits which allow them to cope and resist their enemies including both insects and fungi . In some cases such traits allow plants to build mutualistic relationships with natural enemies of plant pests. This is the case in many dicotyledonous plants which produce leaf domatia. Leaf domatia are plant cavities usually found in the axils of major veins in the abaxial side of leaves. They are usually associated with mites and often mediate mutualistic relationships with predacious mites. Mites use leaf domatia primarily for shelter, to reproduce, and to develop. In turn, plants benefit from having predaceous mites on their leaves, because mites act as plant “bodyguards” and offer defence against pathogens and small arthropod herbivores. This phenomenon has been well documented all over the world, but Africa remains disproportionally understudied. The aim of this study was to fill the gap that exists in our knowledge of the extent of the distribution of leaf domatia-mite mutualisms and generate a better understanding of the diversity of mites found within leaf domatia from an African perspective. This was done by surveying plant species that bear leaf domatia from different vegetation types in South Africa. The plants with leaf domatia were examined for the presence of mites in order to determine patterns of mite abundance and diversity and, in so doing, address the following questions: • Does each tree species host have a specific mite or mite assemblage? • Do some mites prefer certain types of leaf domatia? • Do mites prefer a specific place in the tree canopy and does the microclimate in the tree canopy affect the distribution of mites? • Do different vegetation sites and types differ in their mite diversity and species composition? • Does mite abundance and diversity vary with seasons? Do coffee plantations have a different suite of mites than the adjacent forest? The anatomical structures of leaf domatia from six selected plant species(Coffea arabica, Gardenia thunbergia, Rothmannia capensis, Rothmannia globosa (Rubiaceae), Ocotea bullata (Lauraceae) and Tecoma capensis (Bignoniaceae) with different types of leaf domatia were also studied. The results from this study suggested that the key futures which distinguish domatia are the presence of an extra layer of tissue in the lower epidermis, a thick cuticle, cuticular folds, the presence of trichomes and an invagination. This study provides a better understating of the structure of leaf domatia. Leaf domatia bearing plants are widely distributed in South Africa, and species and vegetation-specific associations were assessed. Over 250 plant specimens with leaf domatia were collected and examined and more than 60 different mite species were found in association with the sampled plant species. The majority of mites found within the domatia of these tree species were predaceous and included mites from Stigmatidae, Tydeidae and Phytoseiidae. Furthermore, 15 new species were collected, suggesting that mites are understudied in South Africa. This study showed that the different vegetation types sampled did not differ markedly in terms of their mite biota and that similar mites were found across the region, and the association between leaf domatia and mites was found to be opportunistic and that mites had no preference for any particular domatia types. No host specificity relationship was observed between plants and mites. The assessment of mites associated with Coffea arabica showed that indigenous mites are able to colonise and establish a beneficial mutualism on exotic species. This is important as it ascertains that economically important plants that are cultivated outside their area of natural distribution can still benefit from this mutualism. This study also found that mite abundance and diversity in plants with leaf domatia were influenced by factors such as temperature, relative humidity and rainfall. Mite communities found in association with domatia changed as the year progressed and over the seasons. The seasonal fluctuations varied between the sampled plant species. In addition, this study found that mites were sensitive to extreme environmental conditions, and thus, mites preferred leaves found in the lower parts of the tree canopy and avoided exposed leaves. This study provides a better understanding of the distribution of domatia bearing plants in South Africa and their associated mites and contributes to our knowledge of the biodiversity of mites in the region. Furthermore, this study also adds to our understanding of the leaf domatia - mite mutualism in Africa. The applied example looking at the plant-mite mutualism in Coffea arabica highlights the importance of this mutualism in commercial plants.
- Full Text:
- Date Issued: 2018
Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) population ecology in citrus orchards: the influence of orchard age
- Authors: Albertyn, Sonnica
- Date: 2018
- Subjects: Cryptophlebia leucotreta , Population biology , Insect populations , Orchards , Insect nematodes , Entomopathogenic fungi
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62615 , vital:28213
- Description: Anecdotal reports in the South African citrus industry claim higher populations of false codling moth (FCM), Thaumatotibia (Cryptophlebia) leucotreta (Meyr) (Lepidoptera: Tortricidae), in orchards during the first three to five harvesting years of citrus planted in virgin soil, after which, FCM numbers seem to decrease and remain consistent. Various laboratory studies and field surveys were conducted to determine if, and why juvenile orchards (four to eight years old) experience higher FCM infestation than mature orchards (nine years and older). In laboratory trials, Washington Navel oranges and Nova Mandarins from juvenile trees were shown to be significantly more susceptible to FCM damage and significantly more attractive for oviposition in both choice and no-choice trials, than fruit from mature trees. Although fruit from juvenile Cambria Navel trees were significantly more attractive than mature orchards for oviposition, they were not more susceptible to FCM damage. In contrast, fruit from juvenile and mature Midnight Valencia orchards were equally attractive for oviposition, but fruit from juvenile trees were significantly more susceptible to FCM damage than fruit from mature trees. Artificial diets were augmented with powder from fruit from juvenile or mature Washington Navel orchards at 5%, 10%, 15% or 30%. Higher larval survival of 76%, 63%, 50% and 34%, respectively, was recorded on diets containing fruit powder from the juvenile trees than on diets containing fruit powder from the mature trees, at 69%, 57%, 44% and 27% larval survival, respectively. Bioassays were conducted to determine if differences in plant chemistry between fruit from juvenile and mature trees will have an impact on the susceptibility FCM to entomopathogenic nematodes (EPN), entomopathogenic fungi (EPF) and Cryptophlebia leucotreta granulovirus (CrleGV). No significant differences in the susceptibility of larvae reared on diets containing 15% fruit powder from juvenile and mature trees to EPN and EPF were recorded. Mortality of neonate larvae was significantly lower when placed on diets containing 15% fruit powder from mature trees (45% mortality) than diets containing 15% fruit powder from juvenile trees (61% mortality), after larvae ingested the lowest virus concentration tested, being 2 x104 OBs/ml. Data collected from field surveys showed significantly lower egg parasitism, virus infection of larvae and EPF occurrence in juvenile orchards than mature orchards. Egg parasitism was between 11% and 54% higher in mature orchards than juvenile orchards, with the exception of Mandarins during 2015, where egg parasitism was slightly higher in juvenile orchards, but not significantly so. A significantly higher proportion of larvae retrieved from mature orchards (7% of larvae) were infected with CrleGV than larvae retrieved from juvenile orchards (4% of larvae). A significantly higher occurrence of EPF was recorded in non-bearing and mature orchards, with 40% and 37% occurrence respectively, than in juvenile orchards, with 25% occurrence recorded. EPF occurrence in juvenile orchards increased significantly by 16% to 32% from the first to the third year of sampling. In contrast to results recorded in laboratory trials, similar or higher pest pressure in juvenile orchards than mature orchards did not always result in significantly higher levels of FCM damage under field conditions. FCM damage in juvenile orchards may have been lower than expected, as greater extremes of temperature and lower humidity were recorded in juvenile orchards, which would increase larval mortality. Results of this study showed that juvenile and mature orchards are significantly different and should be managed differently.
- Full Text:
- Date Issued: 2018
- Authors: Albertyn, Sonnica
- Date: 2018
- Subjects: Cryptophlebia leucotreta , Population biology , Insect populations , Orchards , Insect nematodes , Entomopathogenic fungi
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62615 , vital:28213
- Description: Anecdotal reports in the South African citrus industry claim higher populations of false codling moth (FCM), Thaumatotibia (Cryptophlebia) leucotreta (Meyr) (Lepidoptera: Tortricidae), in orchards during the first three to five harvesting years of citrus planted in virgin soil, after which, FCM numbers seem to decrease and remain consistent. Various laboratory studies and field surveys were conducted to determine if, and why juvenile orchards (four to eight years old) experience higher FCM infestation than mature orchards (nine years and older). In laboratory trials, Washington Navel oranges and Nova Mandarins from juvenile trees were shown to be significantly more susceptible to FCM damage and significantly more attractive for oviposition in both choice and no-choice trials, than fruit from mature trees. Although fruit from juvenile Cambria Navel trees were significantly more attractive than mature orchards for oviposition, they were not more susceptible to FCM damage. In contrast, fruit from juvenile and mature Midnight Valencia orchards were equally attractive for oviposition, but fruit from juvenile trees were significantly more susceptible to FCM damage than fruit from mature trees. Artificial diets were augmented with powder from fruit from juvenile or mature Washington Navel orchards at 5%, 10%, 15% or 30%. Higher larval survival of 76%, 63%, 50% and 34%, respectively, was recorded on diets containing fruit powder from the juvenile trees than on diets containing fruit powder from the mature trees, at 69%, 57%, 44% and 27% larval survival, respectively. Bioassays were conducted to determine if differences in plant chemistry between fruit from juvenile and mature trees will have an impact on the susceptibility FCM to entomopathogenic nematodes (EPN), entomopathogenic fungi (EPF) and Cryptophlebia leucotreta granulovirus (CrleGV). No significant differences in the susceptibility of larvae reared on diets containing 15% fruit powder from juvenile and mature trees to EPN and EPF were recorded. Mortality of neonate larvae was significantly lower when placed on diets containing 15% fruit powder from mature trees (45% mortality) than diets containing 15% fruit powder from juvenile trees (61% mortality), after larvae ingested the lowest virus concentration tested, being 2 x104 OBs/ml. Data collected from field surveys showed significantly lower egg parasitism, virus infection of larvae and EPF occurrence in juvenile orchards than mature orchards. Egg parasitism was between 11% and 54% higher in mature orchards than juvenile orchards, with the exception of Mandarins during 2015, where egg parasitism was slightly higher in juvenile orchards, but not significantly so. A significantly higher proportion of larvae retrieved from mature orchards (7% of larvae) were infected with CrleGV than larvae retrieved from juvenile orchards (4% of larvae). A significantly higher occurrence of EPF was recorded in non-bearing and mature orchards, with 40% and 37% occurrence respectively, than in juvenile orchards, with 25% occurrence recorded. EPF occurrence in juvenile orchards increased significantly by 16% to 32% from the first to the third year of sampling. In contrast to results recorded in laboratory trials, similar or higher pest pressure in juvenile orchards than mature orchards did not always result in significantly higher levels of FCM damage under field conditions. FCM damage in juvenile orchards may have been lower than expected, as greater extremes of temperature and lower humidity were recorded in juvenile orchards, which would increase larval mortality. Results of this study showed that juvenile and mature orchards are significantly different and should be managed differently.
- Full Text:
- Date Issued: 2018