Quantifying crop damage by Grey crowned crane balearica regulorum regulorum and evaluating changes in crane distribution in the North Eastern Cape, South Africa
- Authors: Van Niekerk, Mark Harry
- Date: 2011
- Subjects: Cranes (Birds) -- South Africa -- Eastern Cape , Cranes (Birds) -- Geographical distribution -- South Africa -- Eastern Cape , Cranes (Birds) -- Behavior -- South Africa -- Eastern Cape , Cranes (Birds) -- Food -- South Africa -- Eastern Cape , Corn -- Effect of grazing on -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5749 , http://hdl.handle.net/10962/d1005436 , Cranes (Birds) -- South Africa -- Eastern Cape , Cranes (Birds) -- Geographical distribution -- South Africa -- Eastern Cape , Cranes (Birds) -- Behavior -- South Africa -- Eastern Cape , Cranes (Birds) -- Food -- South Africa -- Eastern Cape , Corn -- Effect of grazing on -- South Africa -- Eastern Cape
- Description: Complaints of crop damage by cranes on planted maize in the North Eastern Cape, South Africa, have been increasing since the mid-1990‘s, and in some instances severe losses have been reported. Crop damage by the Grey Crowned Crane Balearica regulorum regulorum near the town of Maclear (31º04´S 28º22´E), has been quantified over two growing seasons, and assessed relative to losses caused by foraging Cape Crows Corvus capensis and other feeding damage assumed to be caused by insects. Twelve fields were selected based on previous patterns of crop depredation. Maize seed in seven of the fields was treated with the chemical ‗Gaucho‘ and five fields were planted with untreated maize. In order to determine the source of losses, twenty quadrats (4 m x 4 m) randomly distributed within each field were visited on average every second day, for a period of up to twenty eight days. Results indicate that seed treatments do act as a deterrent to feeding by both cranes and crows, however crane damage is generally insignificant compared to other sources of damage. My study also reviewed past sightings data of the Grey Crowned Crane in an effort to determine if the conversion of former grassland to plantations in this region may have increased foraging activity in maize fields. The data did not allow for clear-cut conclusions regarding changes in distribution or population trends. Conclusions provide direct input into the management of agricultural areas by enabling landowners to take steps to mitigate crop damage. These mitigation measures may either involve the application of seed treatments, or the planting of low risk crops in high risk areas. Future studies should consider the ppossible detrimental effects of chemical seed treatments on crane biology.
- Full Text:
- Date Issued: 2011
- Authors: Van Niekerk, Mark Harry
- Date: 2011
- Subjects: Cranes (Birds) -- South Africa -- Eastern Cape , Cranes (Birds) -- Geographical distribution -- South Africa -- Eastern Cape , Cranes (Birds) -- Behavior -- South Africa -- Eastern Cape , Cranes (Birds) -- Food -- South Africa -- Eastern Cape , Corn -- Effect of grazing on -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5749 , http://hdl.handle.net/10962/d1005436 , Cranes (Birds) -- South Africa -- Eastern Cape , Cranes (Birds) -- Geographical distribution -- South Africa -- Eastern Cape , Cranes (Birds) -- Behavior -- South Africa -- Eastern Cape , Cranes (Birds) -- Food -- South Africa -- Eastern Cape , Corn -- Effect of grazing on -- South Africa -- Eastern Cape
- Description: Complaints of crop damage by cranes on planted maize in the North Eastern Cape, South Africa, have been increasing since the mid-1990‘s, and in some instances severe losses have been reported. Crop damage by the Grey Crowned Crane Balearica regulorum regulorum near the town of Maclear (31º04´S 28º22´E), has been quantified over two growing seasons, and assessed relative to losses caused by foraging Cape Crows Corvus capensis and other feeding damage assumed to be caused by insects. Twelve fields were selected based on previous patterns of crop depredation. Maize seed in seven of the fields was treated with the chemical ‗Gaucho‘ and five fields were planted with untreated maize. In order to determine the source of losses, twenty quadrats (4 m x 4 m) randomly distributed within each field were visited on average every second day, for a period of up to twenty eight days. Results indicate that seed treatments do act as a deterrent to feeding by both cranes and crows, however crane damage is generally insignificant compared to other sources of damage. My study also reviewed past sightings data of the Grey Crowned Crane in an effort to determine if the conversion of former grassland to plantations in this region may have increased foraging activity in maize fields. The data did not allow for clear-cut conclusions regarding changes in distribution or population trends. Conclusions provide direct input into the management of agricultural areas by enabling landowners to take steps to mitigate crop damage. These mitigation measures may either involve the application of seed treatments, or the planting of low risk crops in high risk areas. Future studies should consider the ppossible detrimental effects of chemical seed treatments on crane biology.
- Full Text:
- Date Issued: 2011
The critical natural capital of the Buffalo City Municipality, South Africa : harnessing local action for biodiversity conservation
- Authors: Hagen, Brett
- Date: 2011
- Subjects: Natural resources -- South Africa -- Buffalo City , Biodiversity conservation -- South Africa -- Buffalo City , Ecosystem services -- South Africa -- Buffalo City , Nature conservation -- South Africa -- Buffalo City , Environmental protection -- South Africa -- Buffalo City , Environmental degradation -- South Africa -- Buffalo City , Restoration ecology -- South Africa -- Buffalo City
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4753 , http://hdl.handle.net/10962/d1007075 , Natural resources -- South Africa -- Buffalo City , Biodiversity conservation -- South Africa -- Buffalo City , Ecosystem services -- South Africa -- Buffalo City , Nature conservation -- South Africa -- Buffalo City , Environmental protection -- South Africa -- Buffalo City , Environmental degradation -- South Africa -- Buffalo City , Restoration ecology -- South Africa -- Buffalo City
- Description: Globally, ecosystems provide services of almost twice the value of global gross national product (Costanza et al., 2006). The Buffalo City Municipality (BCM), South Africa contains biodiversity of national and international importance (Pierce, 2003; Pierce et al., 2005). Despite this, the municipality continues to experience loss of both urban and rural biodiversity (Buffalo City Municipality, 2006a). This study sought to determine the status of biodiversity, and the potential for ecosystem services to contribute to conservation, within the BCM. Biodiversity features, including ecosystem type, species of special concern and biodiversity processes, were identified and mapped using a GIS to produce a biodiversity priority index for the BCM. Current transformation status was then mapped to determine the level of ecosystem degradation within the BCM. Priority biodiversity areas as well as individual biodiversity features were spatially overlain against current transformation status and protected areas and analysed using a GIS to determine the level of degradation and protection of BCM biodiversity. In total 3.5 % of total BCM biodiversity was protected. Of the 24 ecosystem types, 11 (45%) had less than 1% under protection, while 16 (67%) had less than five percent protected. Not restorable areas, thus completely lost to biodiversity conservation, comprised just less than a quarter of the total BCM area while un-impacted areas comprised just 12.3%. Twenty five ecosystem services were identified as being provided by intact natural ecosystems within the BCM. The natural capital providing these services was identified and mapped to produce an ecosystem service index (ESI) using a GIS. This ecosystem service index and the biodiversity priority index were overlain to determine their level of correlation. Overall ESI correlation with priority biodiversity was weak although several individual ecosystem services, including carbon sequestration, showed correlation. Using the above data layers an implementation plan and conservation framework was proposed to assist the coordination of local conservation action within the BCM. It is concluded that ecosystem services are a potentially useful tool for conservationists at the local level seeking to ensure that biodiversity has relevance to and receives protection from broader society.
- Full Text:
- Date Issued: 2011
- Authors: Hagen, Brett
- Date: 2011
- Subjects: Natural resources -- South Africa -- Buffalo City , Biodiversity conservation -- South Africa -- Buffalo City , Ecosystem services -- South Africa -- Buffalo City , Nature conservation -- South Africa -- Buffalo City , Environmental protection -- South Africa -- Buffalo City , Environmental degradation -- South Africa -- Buffalo City , Restoration ecology -- South Africa -- Buffalo City
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4753 , http://hdl.handle.net/10962/d1007075 , Natural resources -- South Africa -- Buffalo City , Biodiversity conservation -- South Africa -- Buffalo City , Ecosystem services -- South Africa -- Buffalo City , Nature conservation -- South Africa -- Buffalo City , Environmental protection -- South Africa -- Buffalo City , Environmental degradation -- South Africa -- Buffalo City , Restoration ecology -- South Africa -- Buffalo City
- Description: Globally, ecosystems provide services of almost twice the value of global gross national product (Costanza et al., 2006). The Buffalo City Municipality (BCM), South Africa contains biodiversity of national and international importance (Pierce, 2003; Pierce et al., 2005). Despite this, the municipality continues to experience loss of both urban and rural biodiversity (Buffalo City Municipality, 2006a). This study sought to determine the status of biodiversity, and the potential for ecosystem services to contribute to conservation, within the BCM. Biodiversity features, including ecosystem type, species of special concern and biodiversity processes, were identified and mapped using a GIS to produce a biodiversity priority index for the BCM. Current transformation status was then mapped to determine the level of ecosystem degradation within the BCM. Priority biodiversity areas as well as individual biodiversity features were spatially overlain against current transformation status and protected areas and analysed using a GIS to determine the level of degradation and protection of BCM biodiversity. In total 3.5 % of total BCM biodiversity was protected. Of the 24 ecosystem types, 11 (45%) had less than 1% under protection, while 16 (67%) had less than five percent protected. Not restorable areas, thus completely lost to biodiversity conservation, comprised just less than a quarter of the total BCM area while un-impacted areas comprised just 12.3%. Twenty five ecosystem services were identified as being provided by intact natural ecosystems within the BCM. The natural capital providing these services was identified and mapped to produce an ecosystem service index (ESI) using a GIS. This ecosystem service index and the biodiversity priority index were overlain to determine their level of correlation. Overall ESI correlation with priority biodiversity was weak although several individual ecosystem services, including carbon sequestration, showed correlation. Using the above data layers an implementation plan and conservation framework was proposed to assist the coordination of local conservation action within the BCM. It is concluded that ecosystem services are a potentially useful tool for conservationists at the local level seeking to ensure that biodiversity has relevance to and receives protection from broader society.
- Full Text:
- Date Issued: 2011
Investigations of the assessment of bioequivalence of topical clotrimazole products using a dermatopharmacokinetic approach
- Authors: Parfitt, Natalie Rae
- Date: 2011 , 2010-07-05
- Subjects: Dermatopharmacology , Drugs -- Therapeutic equivalency , Antifungal agents , Therapeutics, Cutaneous and external
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3840 , http://hdl.handle.net/10962/d1007659 , Dermatopharmacology , Drugs -- Therapeutic equivalency , Antifungal agents , Therapeutics, Cutaneous and external
- Description: The specialised nature of the stratum corneum makes it an efficient barrier to foreign substances, including drug molecules. Therefore, cutaneous drug absorption is a slow and complex process of which stratum corneum penetration is the rate limiting step. The rate and extent of stratum corneum penetration by a drug compound depends greatly on the presence of penetration enhancing/retarding excipients and therefore the clinical outcomes of a product rely greatly on the components and quality of the formulation. Hence, establishing bioequivalence between topical products is crucial to ensure that patients receiving multisource drug products are assured of the same efficacy and safety as the brand product. Since locally acting topical formulations do not target the systemic circulation, conventional methods of assessing bioequivalence using plasma levels are not appropriate. Consequently, the current regulatory guidelines require comparative clinical trials to be carried out to show bioequivalence between topical products. As these studies are very expensive and time consuming, the development of a more direct and relatively rapid and inexpensive method for determining bioequivalence between topical products is required. Clotrimazole is an anti-fungal agent where the target site of action is in the stratum corneum. In this work, tape stripping, which involves the sampling of stratum corneum, was investigated as a tool for the determination of bioequivalence between topical clotrimazole products. The tape stripping method involved the analysis of each tape strip individually and standardization of stratum corneum thickness between subjects was carried out using TEWL measurements. This approach provided detailed information regarding the amount of clotrimazole present in the stratum corneum as well as the extent of drug penetration. Prior to the tape stripping studies an HPLC method was developed for the quantitative analysis of clotrimazole from the tape strip samples. This method was shown to be accurate and reproducible across the required range. It was also shown to be selective for clotrimazole in the presence of possible interfering substances such as those present in the tape adhesive and also skin components. The bioequivalence studies were conducted using a single “uptake” time point. In order to determine an appropriate dose duration for these studies a novel approach was employed, involving a preliminary dose duration study. For the bioequivalence investigations, Canesten® Topical cream was used as both test and reference products to determine if the method was capable of showing bioequivalence. Subsequently, Canesten® Topical cream was also compared to a 1% gel formulation to determine if the method could detect formulation differences. The conventional BE limits of 0.8 – 1.25 were used for the assessment of BE, however, the clinical relevance of using these limits for dermal studies is debatable since they are derived from oral pharmacokinetic studies. Therefore, the data from the tape stripping investigations were also assessed using more realistic limits of 0.75 – 1.33 and even 0.7 – 1.44. In addition to the tape stripping studies a novel method of determining the amount of drug present in the stratum corneum, the “Residual Method”, was investigated. This method involved assaying the amount of clotrimazole found in the residual formulation after a specified dose duration had elapsed and subtracting that amount from the amount of clotrimazole initially applied. The results of tape stripping investigations showed that, if the study is sufficiently powered, tape stripping may be used to determine bioequivalence according to the conventional limits, as well as possibly detect formulation differences between different clotrimazole products. Bioequivalence assessment using the widened intervals showed that fewer subjects were required to achieve a sufficient statistical power. The variability associated with this method was acceptable and tape stripping may therefore have the potential to be used as a BE tool in a regulatory setting for clotrimazole or other antifungal topical formulations. The “Residual Method” also showed promising results as a bioequivalence tool, but further investigation and extensive validation of this method is required before it can be suggested as a regulatory method. The results of these studies have clearly indicated that tape stripping has the potential to be used as an alternative to comparative clinical trails for the assessment of bioequivalence between clotrimazole formulations and also to assess bioequivalence between other antifungal products.
- Full Text:
- Date Issued: 2011
- Authors: Parfitt, Natalie Rae
- Date: 2011 , 2010-07-05
- Subjects: Dermatopharmacology , Drugs -- Therapeutic equivalency , Antifungal agents , Therapeutics, Cutaneous and external
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3840 , http://hdl.handle.net/10962/d1007659 , Dermatopharmacology , Drugs -- Therapeutic equivalency , Antifungal agents , Therapeutics, Cutaneous and external
- Description: The specialised nature of the stratum corneum makes it an efficient barrier to foreign substances, including drug molecules. Therefore, cutaneous drug absorption is a slow and complex process of which stratum corneum penetration is the rate limiting step. The rate and extent of stratum corneum penetration by a drug compound depends greatly on the presence of penetration enhancing/retarding excipients and therefore the clinical outcomes of a product rely greatly on the components and quality of the formulation. Hence, establishing bioequivalence between topical products is crucial to ensure that patients receiving multisource drug products are assured of the same efficacy and safety as the brand product. Since locally acting topical formulations do not target the systemic circulation, conventional methods of assessing bioequivalence using plasma levels are not appropriate. Consequently, the current regulatory guidelines require comparative clinical trials to be carried out to show bioequivalence between topical products. As these studies are very expensive and time consuming, the development of a more direct and relatively rapid and inexpensive method for determining bioequivalence between topical products is required. Clotrimazole is an anti-fungal agent where the target site of action is in the stratum corneum. In this work, tape stripping, which involves the sampling of stratum corneum, was investigated as a tool for the determination of bioequivalence between topical clotrimazole products. The tape stripping method involved the analysis of each tape strip individually and standardization of stratum corneum thickness between subjects was carried out using TEWL measurements. This approach provided detailed information regarding the amount of clotrimazole present in the stratum corneum as well as the extent of drug penetration. Prior to the tape stripping studies an HPLC method was developed for the quantitative analysis of clotrimazole from the tape strip samples. This method was shown to be accurate and reproducible across the required range. It was also shown to be selective for clotrimazole in the presence of possible interfering substances such as those present in the tape adhesive and also skin components. The bioequivalence studies were conducted using a single “uptake” time point. In order to determine an appropriate dose duration for these studies a novel approach was employed, involving a preliminary dose duration study. For the bioequivalence investigations, Canesten® Topical cream was used as both test and reference products to determine if the method was capable of showing bioequivalence. Subsequently, Canesten® Topical cream was also compared to a 1% gel formulation to determine if the method could detect formulation differences. The conventional BE limits of 0.8 – 1.25 were used for the assessment of BE, however, the clinical relevance of using these limits for dermal studies is debatable since they are derived from oral pharmacokinetic studies. Therefore, the data from the tape stripping investigations were also assessed using more realistic limits of 0.75 – 1.33 and even 0.7 – 1.44. In addition to the tape stripping studies a novel method of determining the amount of drug present in the stratum corneum, the “Residual Method”, was investigated. This method involved assaying the amount of clotrimazole found in the residual formulation after a specified dose duration had elapsed and subtracting that amount from the amount of clotrimazole initially applied. The results of tape stripping investigations showed that, if the study is sufficiently powered, tape stripping may be used to determine bioequivalence according to the conventional limits, as well as possibly detect formulation differences between different clotrimazole products. Bioequivalence assessment using the widened intervals showed that fewer subjects were required to achieve a sufficient statistical power. The variability associated with this method was acceptable and tape stripping may therefore have the potential to be used as a BE tool in a regulatory setting for clotrimazole or other antifungal topical formulations. The “Residual Method” also showed promising results as a bioequivalence tool, but further investigation and extensive validation of this method is required before it can be suggested as a regulatory method. The results of these studies have clearly indicated that tape stripping has the potential to be used as an alternative to comparative clinical trails for the assessment of bioequivalence between clotrimazole formulations and also to assess bioequivalence between other antifungal products.
- Full Text:
- Date Issued: 2011
Neogene fluvial deposits along the south-west coast of South Africa understanding the palaeoclimate through proxies
- Authors: Sciscio, Lara
- Date: 2011
- Subjects: Alluvium , Paleoclimatology -- South Africa , Paleoecology -- Miocene -- South Africa , Paleobotany -- Miocene -- South Africa , Paleogeography -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4981 , http://hdl.handle.net/10962/d1005593 , Alluvium , Paleoclimatology -- South Africa , Paleoecology -- Miocene -- South Africa , Paleobotany -- Miocene -- South Africa , Paleogeography -- South Africa
- Description: Branched glycerol dialkyl glycerol tetraether (GDGTs) membrane lipids have been used as a new proxy for the reconstruction of terrestrial palaeoclimates. These biomarkers (or molecular ‗fossils‘) in conjunction with palynology, have been effective in the novel analysis of Miocene organic-rich sediments from three South African west coast sites at Rondeberg, Noordhoek and Langebaanweg. Lastly, a Quaternary south coast site at Rietvlei, South Africa, was also studied to further elucidate the extent of use of this new proxy. The fluvial peat and organic-rich deposits of the Elandsfontyn Formation (Sandveld Group) were investigated at Noordhoek, Langebaanweg and Rondeberg to provide new evidence for the climate and vegetation patterns during Miocene in this region. Drill-core and quarry samples from all four sites were freeze-dried, powered, and prepared for biogeochemical and palynological analyses. The methylation index of branched tetraethers (MBT) and cyclisation ratio of branched tetraethers (CBT) proxies were used to calculate the mean annual air temperature (MAAT) and pH values of the organic-rich horizons at time of deposition. The Branched versus isoprenoid index of tetraethers (BIT) was used to assess the relative contributions of marine archaeal and terrestrial bacterial tetraethers, and thereby assess the validity of the MBT, CBT and calculated palaeoenvironmental factors. The results presented in this thesis suggest that the use of the MBT/CBT proxy has significant potential in southern Africa, and may complement previously attempted palaeoclimatic and palaeoecological studies of Neogene-aged South African sediments. This type of research has the capacity to provide palaeoenvironmental information where other proxies may be absent. Results indicate that all sites yielded branched tetraether membrane lipids with the exception of Rondeberg, where GDGTs were below detection as a result of poor preservation conditions. Palynological investigation confirmed proxy derived temperatures. Furthermore palynomorph analyses supplemented earlier studies of the Noordhoek site and were piloted for the Rondeberg site, reaffirming alternating sequences of tropical and subtropical palynofloras. The MAATs, likewise, show variability and pronounced trends through time at the Langebaanweg and Noordhoek sites, generally corresponding with the variation and diversity of the pollen population. The terrestrial MAAT results appear to compliment Southern Hemisphere sea level changes associated with Antarctic glaciations. Additionally, this data shows a pattern similar to the Southern and Northern Hemisphere marine isotope records of relative fluctuations in the global climate and sea level change from the early to middle Miocene. The application of these past climate change indicators have been proved to be useful in the reconstruction of South Africa Miocene palaeoclimates, and may aid in understanding the consequences of climate change in the Cape region.
- Full Text:
- Date Issued: 2011
- Authors: Sciscio, Lara
- Date: 2011
- Subjects: Alluvium , Paleoclimatology -- South Africa , Paleoecology -- Miocene -- South Africa , Paleobotany -- Miocene -- South Africa , Paleogeography -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4981 , http://hdl.handle.net/10962/d1005593 , Alluvium , Paleoclimatology -- South Africa , Paleoecology -- Miocene -- South Africa , Paleobotany -- Miocene -- South Africa , Paleogeography -- South Africa
- Description: Branched glycerol dialkyl glycerol tetraether (GDGTs) membrane lipids have been used as a new proxy for the reconstruction of terrestrial palaeoclimates. These biomarkers (or molecular ‗fossils‘) in conjunction with palynology, have been effective in the novel analysis of Miocene organic-rich sediments from three South African west coast sites at Rondeberg, Noordhoek and Langebaanweg. Lastly, a Quaternary south coast site at Rietvlei, South Africa, was also studied to further elucidate the extent of use of this new proxy. The fluvial peat and organic-rich deposits of the Elandsfontyn Formation (Sandveld Group) were investigated at Noordhoek, Langebaanweg and Rondeberg to provide new evidence for the climate and vegetation patterns during Miocene in this region. Drill-core and quarry samples from all four sites were freeze-dried, powered, and prepared for biogeochemical and palynological analyses. The methylation index of branched tetraethers (MBT) and cyclisation ratio of branched tetraethers (CBT) proxies were used to calculate the mean annual air temperature (MAAT) and pH values of the organic-rich horizons at time of deposition. The Branched versus isoprenoid index of tetraethers (BIT) was used to assess the relative contributions of marine archaeal and terrestrial bacterial tetraethers, and thereby assess the validity of the MBT, CBT and calculated palaeoenvironmental factors. The results presented in this thesis suggest that the use of the MBT/CBT proxy has significant potential in southern Africa, and may complement previously attempted palaeoclimatic and palaeoecological studies of Neogene-aged South African sediments. This type of research has the capacity to provide palaeoenvironmental information where other proxies may be absent. Results indicate that all sites yielded branched tetraether membrane lipids with the exception of Rondeberg, where GDGTs were below detection as a result of poor preservation conditions. Palynological investigation confirmed proxy derived temperatures. Furthermore palynomorph analyses supplemented earlier studies of the Noordhoek site and were piloted for the Rondeberg site, reaffirming alternating sequences of tropical and subtropical palynofloras. The MAATs, likewise, show variability and pronounced trends through time at the Langebaanweg and Noordhoek sites, generally corresponding with the variation and diversity of the pollen population. The terrestrial MAAT results appear to compliment Southern Hemisphere sea level changes associated with Antarctic glaciations. Additionally, this data shows a pattern similar to the Southern and Northern Hemisphere marine isotope records of relative fluctuations in the global climate and sea level change from the early to middle Miocene. The application of these past climate change indicators have been proved to be useful in the reconstruction of South Africa Miocene palaeoclimates, and may aid in understanding the consequences of climate change in the Cape region.
- Full Text:
- Date Issued: 2011
Male and female cardiovascular risk in an urban, black working population
- Authors: Jackson, Lindsay May
- Date: 2011
- Subjects: Cardiovascular system -- Diseases -- South Africa -- Grahamstown , Obesity -- South Africa -- Grahamstown , Hypertension -- South Africa -- Grahamstown , Hypercholesteremia -- South Africa -- Grahamstown , Diabetes -- South Africa -- Grahamstown , Lifestyles -- Health aspects -- South Africa -- Grahamstown , Health behavior -- South Africa -- Grahamstown , Health attitudes -- South Africa -- Grahamstown , Black people -- South Africa -- Grahamstown -- Health and hygiene
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5127 , http://hdl.handle.net/10962/d1005205 , Cardiovascular system -- Diseases -- South Africa -- Grahamstown , Obesity -- South Africa -- Grahamstown , Hypertension -- South Africa -- Grahamstown , Hypercholesteremia -- South Africa -- Grahamstown , Diabetes -- South Africa -- Grahamstown , Lifestyles -- Health aspects -- South Africa -- Grahamstown , Health behavior -- South Africa -- Grahamstown , Health attitudes -- South Africa -- Grahamstown , Black people -- South Africa -- Grahamstown -- Health and hygiene
- Description: The aim of this research project was to assess and compare cardiovascular disease (CVD) risk in black males and females from an urban, working population in the Makana (Grahamstown) region of the Eastern Cape, South Africa. Two-hundred and ninety one individuals (males: n = 143, females: n = 148) with a mean age of 42.6 (±8.1) years were voluntarily recruited from the greater urban Makana (Grahamstown) area. Eight Cardiovascular disease (CVD) risks were assessed: stature and mass were obtained in order to calculate body mass index (BMI) (mass/stature2). Obesity, defined as a morphological risk, was classified according to the World Health Organisation (WHO) BMI criteria (BMI>30kg.m-2), as well as according to measures of waist circumference (WC) and body composition. Hypertension, hypercholesterolemia and type II diabetes, were grouped as cardiovascular (CV) risks. Hypertension was defined as a blood pressure greater than 140/90mmHg (JNC-7); hypercholesterolemia, as total cholesterol greater than 6.2mmol.L-1 (NCEP); and type II diabetes, as total glucose greater than 12mmol.L-1 (WHO). Physical activity, diet, tobacco use, and alcohol consumption and dependence were grouped as lifestyle-related risks. These were assessed by means of self-reporting through the use of various validated questionnaires. Finally, self-reporting of obesity, hypertension, hypercholesterolemia and type II diabetes was assessed, in addition to perception questions on individuals’ perceived body shape and size (Ziebland figures). Self-reported and perceived responses were then compared to actual measures. Females were significantly (p<0.001) heavier than the males (92.7kg compared to 72.1kg) and had significantly (p<0.001) higher BMIs than their male counterparts (37.6kg.m-2 compared to 25.7 kg.-2). They also recorded significantly (p<0.001) higher waist circumference (WC) values and had significantly (p<0.001) higher percentage and total body fat. Significantly (p<0.001) more females were obese (81%) compared to males (17%). While a higher percentage of males (25 % compared to 22%) presented with stage I hypertension (≥140/90mmHg, <160/95mmHg), significantly (p<0.05) more females (14% compared to 8%) presented with stage II hypertension (>160/95mmHg). The prevalence of hypercholesterolemia at a high level of risk (>6.2mmol.L-1) was relatively low (2.1 % of males, 3.4% of females), but notably more participants (22% of males and 26% of females) presented with the condition at a moderate level of risk (>5mmol.L-1). Type II diabetes was the least prevalent CV risk factor, with no males and only 3% of females presenting with the condition. Males consumed significantly (p<0.05) more in terms of total energy intake (9024 vs. 7234 kJ) and were significantly (p<0.05) more active (3315 compared to 2660 MET-mins.week). A significantly (p<0.05) higher percentage of males smoked (51.1% compared to 3.4%), consumed alcohol (73.4% compared to 46.6%) and were alcohol dependent (40% compared to 33.5%). Both males and females tended to be ignorant of their health status, with both samples under-reporting obesity, hypertension and hypercholesterolemia, while over-reporting type II diabetes. Furthermore, obesity was significantly (p<0.05) underestimated, with both male and female individuals perceiving themselves to be notably smaller than they actually were. Physical activity and diet were important determinants of CVD risk in this black urban sample of individuals. Obesity, in particular central adiposity, was the most notable risk (particularly in females), followed by hypertension (particularly in males). Although some risks presented at a moderate level of risk, a clustering of risk factors was evident in both samples, with 12.6% and 41.2% of males and females presenting with two risk factors, and 2.8% and 8.1% of males and females respectively presenting with three risks.
- Full Text:
- Date Issued: 2011
- Authors: Jackson, Lindsay May
- Date: 2011
- Subjects: Cardiovascular system -- Diseases -- South Africa -- Grahamstown , Obesity -- South Africa -- Grahamstown , Hypertension -- South Africa -- Grahamstown , Hypercholesteremia -- South Africa -- Grahamstown , Diabetes -- South Africa -- Grahamstown , Lifestyles -- Health aspects -- South Africa -- Grahamstown , Health behavior -- South Africa -- Grahamstown , Health attitudes -- South Africa -- Grahamstown , Black people -- South Africa -- Grahamstown -- Health and hygiene
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5127 , http://hdl.handle.net/10962/d1005205 , Cardiovascular system -- Diseases -- South Africa -- Grahamstown , Obesity -- South Africa -- Grahamstown , Hypertension -- South Africa -- Grahamstown , Hypercholesteremia -- South Africa -- Grahamstown , Diabetes -- South Africa -- Grahamstown , Lifestyles -- Health aspects -- South Africa -- Grahamstown , Health behavior -- South Africa -- Grahamstown , Health attitudes -- South Africa -- Grahamstown , Black people -- South Africa -- Grahamstown -- Health and hygiene
- Description: The aim of this research project was to assess and compare cardiovascular disease (CVD) risk in black males and females from an urban, working population in the Makana (Grahamstown) region of the Eastern Cape, South Africa. Two-hundred and ninety one individuals (males: n = 143, females: n = 148) with a mean age of 42.6 (±8.1) years were voluntarily recruited from the greater urban Makana (Grahamstown) area. Eight Cardiovascular disease (CVD) risks were assessed: stature and mass were obtained in order to calculate body mass index (BMI) (mass/stature2). Obesity, defined as a morphological risk, was classified according to the World Health Organisation (WHO) BMI criteria (BMI>30kg.m-2), as well as according to measures of waist circumference (WC) and body composition. Hypertension, hypercholesterolemia and type II diabetes, were grouped as cardiovascular (CV) risks. Hypertension was defined as a blood pressure greater than 140/90mmHg (JNC-7); hypercholesterolemia, as total cholesterol greater than 6.2mmol.L-1 (NCEP); and type II diabetes, as total glucose greater than 12mmol.L-1 (WHO). Physical activity, diet, tobacco use, and alcohol consumption and dependence were grouped as lifestyle-related risks. These were assessed by means of self-reporting through the use of various validated questionnaires. Finally, self-reporting of obesity, hypertension, hypercholesterolemia and type II diabetes was assessed, in addition to perception questions on individuals’ perceived body shape and size (Ziebland figures). Self-reported and perceived responses were then compared to actual measures. Females were significantly (p<0.001) heavier than the males (92.7kg compared to 72.1kg) and had significantly (p<0.001) higher BMIs than their male counterparts (37.6kg.m-2 compared to 25.7 kg.-2). They also recorded significantly (p<0.001) higher waist circumference (WC) values and had significantly (p<0.001) higher percentage and total body fat. Significantly (p<0.001) more females were obese (81%) compared to males (17%). While a higher percentage of males (25 % compared to 22%) presented with stage I hypertension (≥140/90mmHg, <160/95mmHg), significantly (p<0.05) more females (14% compared to 8%) presented with stage II hypertension (>160/95mmHg). The prevalence of hypercholesterolemia at a high level of risk (>6.2mmol.L-1) was relatively low (2.1 % of males, 3.4% of females), but notably more participants (22% of males and 26% of females) presented with the condition at a moderate level of risk (>5mmol.L-1). Type II diabetes was the least prevalent CV risk factor, with no males and only 3% of females presenting with the condition. Males consumed significantly (p<0.05) more in terms of total energy intake (9024 vs. 7234 kJ) and were significantly (p<0.05) more active (3315 compared to 2660 MET-mins.week). A significantly (p<0.05) higher percentage of males smoked (51.1% compared to 3.4%), consumed alcohol (73.4% compared to 46.6%) and were alcohol dependent (40% compared to 33.5%). Both males and females tended to be ignorant of their health status, with both samples under-reporting obesity, hypertension and hypercholesterolemia, while over-reporting type II diabetes. Furthermore, obesity was significantly (p<0.05) underestimated, with both male and female individuals perceiving themselves to be notably smaller than they actually were. Physical activity and diet were important determinants of CVD risk in this black urban sample of individuals. Obesity, in particular central adiposity, was the most notable risk (particularly in females), followed by hypertension (particularly in males). Although some risks presented at a moderate level of risk, a clustering of risk factors was evident in both samples, with 12.6% and 41.2% of males and females presenting with two risk factors, and 2.8% and 8.1% of males and females respectively presenting with three risks.
- Full Text:
- Date Issued: 2011
A platform for computer-assisted multilingual literacy development
- Authors: Mudimba, Bwini Chizabubi
- Date: 2011
- Subjects: FundaWethu , Language acquisition -- Computer-assisted instruction , Language arts (Elementary) -- Computer-assisted instruction , Language and education , Education, Bilingual , Computer-assisted instruction , Educational technology , Computers and literacy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4600 , http://hdl.handle.net/10962/d1004850 , FundaWethu , Language acquisition -- Computer-assisted instruction , Language arts (Elementary) -- Computer-assisted instruction , Language and education , Education, Bilingual , Computer-assisted instruction , Educational technology , Computers and literacy
- Description: FundaWethu is reading software that is designed to deliver reading lessons to Grade R-3 (foundation phase) children who are learning to read in a multilingual context. Starting from a premise that the system should be both educative and entertaining, the system allows literacy researchers or teachers to construct rich multimedia reading lessons, with text, pictures (possibly animated), and audio files. Using the design-based research methodology which is problem driven and iterative, we followed a user-centred design process in creating FundaWethu. To promote sustainability of the software, we chose to bring teachers on board as “co-designers” using the lesson authoring tool. We made the authoring tool simple enough for use by non computer specialists, but expressive enough to enable a wide range of beginners reading exercises to be constructed in a number of different languages (indigenous South African languages in particular). This project therefore centred on the use of designbased research to build FundaWethu, the design and construction of FundaWethu and the usability study carried out to determine the adequacy of FundaWethu.
- Full Text:
- Date Issued: 2011
- Authors: Mudimba, Bwini Chizabubi
- Date: 2011
- Subjects: FundaWethu , Language acquisition -- Computer-assisted instruction , Language arts (Elementary) -- Computer-assisted instruction , Language and education , Education, Bilingual , Computer-assisted instruction , Educational technology , Computers and literacy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4600 , http://hdl.handle.net/10962/d1004850 , FundaWethu , Language acquisition -- Computer-assisted instruction , Language arts (Elementary) -- Computer-assisted instruction , Language and education , Education, Bilingual , Computer-assisted instruction , Educational technology , Computers and literacy
- Description: FundaWethu is reading software that is designed to deliver reading lessons to Grade R-3 (foundation phase) children who are learning to read in a multilingual context. Starting from a premise that the system should be both educative and entertaining, the system allows literacy researchers or teachers to construct rich multimedia reading lessons, with text, pictures (possibly animated), and audio files. Using the design-based research methodology which is problem driven and iterative, we followed a user-centred design process in creating FundaWethu. To promote sustainability of the software, we chose to bring teachers on board as “co-designers” using the lesson authoring tool. We made the authoring tool simple enough for use by non computer specialists, but expressive enough to enable a wide range of beginners reading exercises to be constructed in a number of different languages (indigenous South African languages in particular). This project therefore centred on the use of designbased research to build FundaWethu, the design and construction of FundaWethu and the usability study carried out to determine the adequacy of FundaWethu.
- Full Text:
- Date Issued: 2011
OVR : a novel architecture for voice-based applications
- Authors: Maema, Mathe
- Date: 2011 , 2011-04-01
- Subjects: Telephone systems -- Research , User interfaces (Computer systems) -- Research , Expert systems (Computer science) , Artificial intelligence , VoiceXML (Document markup language) , Application software -- Development
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4671 , http://hdl.handle.net/10962/d1006694 , Telephone systems -- Research , User interfaces (Computer systems) -- Research , Expert systems (Computer science) , Artificial intelligence , VoiceXML (Document markup language) , Application software -- Development
- Description: Despite the inherent limitation of accessing information serially, voice applications are increasingly growing in popularity as computing technologies advance. This is a positive development, because voice communication offers a number of benefits over other forms of communication. For example, voice may be better for delivering services to users whose eyes and hands may be engaged in other activities (e.g. driving) or to semi-literate or illiterate users. This thesis proposes a knowledge based architecture for building voice applications to help reduce the limitations of serial access to information. The proposed architecture, called OVR (Ontologies, VoiceXML and Reasoners), uses a rich backend that represents knowledge via ontologies and utilises reasoning engines to reason with it, in order to generate intelligent behaviour. Ontologies were chosen over other knowledge representation formalisms because of their expressivity and executable format, and because current trends suggest a general shift towards the use of ontologies in many systems used for information storing and sharing. For the frontend, this architecture uses VoiceXML, the emerging, and de facto standard for voice automated applications. A functional prototype was built for an initial validation of the architecture. The system is a simple voice application to help locate information about service providers that offer HIV (Human Immunodeficiency Virus) testing. We called this implementation HTLS (HIV Testing Locator System). The functional prototype was implemented using a number of technologies. OWL API, a Java interface designed to facilitate manipulation of ontologies authored in OWL was used to build a customised query interface for HTLS. Pellet reasoner was used for supporting queries to the knowledge base and Drools (JBoss rule engine) was used for processing dialog rules. VXI was used as the VoiceXML browser and an experimental softswitch called iLanga as the bridge to the telephony system. (At the heart of iLanga is Asterisk, a well known PBX-in-a-box.) HTLS behaved properly under system testing, providing the sought initial validation of OVR. , LaTeX with hyperref package
- Full Text:
- Date Issued: 2011
- Authors: Maema, Mathe
- Date: 2011 , 2011-04-01
- Subjects: Telephone systems -- Research , User interfaces (Computer systems) -- Research , Expert systems (Computer science) , Artificial intelligence , VoiceXML (Document markup language) , Application software -- Development
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4671 , http://hdl.handle.net/10962/d1006694 , Telephone systems -- Research , User interfaces (Computer systems) -- Research , Expert systems (Computer science) , Artificial intelligence , VoiceXML (Document markup language) , Application software -- Development
- Description: Despite the inherent limitation of accessing information serially, voice applications are increasingly growing in popularity as computing technologies advance. This is a positive development, because voice communication offers a number of benefits over other forms of communication. For example, voice may be better for delivering services to users whose eyes and hands may be engaged in other activities (e.g. driving) or to semi-literate or illiterate users. This thesis proposes a knowledge based architecture for building voice applications to help reduce the limitations of serial access to information. The proposed architecture, called OVR (Ontologies, VoiceXML and Reasoners), uses a rich backend that represents knowledge via ontologies and utilises reasoning engines to reason with it, in order to generate intelligent behaviour. Ontologies were chosen over other knowledge representation formalisms because of their expressivity and executable format, and because current trends suggest a general shift towards the use of ontologies in many systems used for information storing and sharing. For the frontend, this architecture uses VoiceXML, the emerging, and de facto standard for voice automated applications. A functional prototype was built for an initial validation of the architecture. The system is a simple voice application to help locate information about service providers that offer HIV (Human Immunodeficiency Virus) testing. We called this implementation HTLS (HIV Testing Locator System). The functional prototype was implemented using a number of technologies. OWL API, a Java interface designed to facilitate manipulation of ontologies authored in OWL was used to build a customised query interface for HTLS. Pellet reasoner was used for supporting queries to the knowledge base and Drools (JBoss rule engine) was used for processing dialog rules. VXI was used as the VoiceXML browser and an experimental softswitch called iLanga as the bridge to the telephony system. (At the heart of iLanga is Asterisk, a well known PBX-in-a-box.) HTLS behaved properly under system testing, providing the sought initial validation of OVR. , LaTeX with hyperref package
- Full Text:
- Date Issued: 2011
Initial investigations into dynamics of mesozooplankton community structure in Algoa Bay, South Africa
- Authors: Dali, Luzuko O'Brian
- Date: 2011
- Subjects: Zooplankton -- Research -- Indian Ocean -- South Africa , Phytoplankton -- Research -- Indian Ocean -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5715 , http://hdl.handle.net/10962/d1005401 , Zooplankton -- Research -- Indian Ocean -- South Africa , Phytoplankton -- Research -- Indian Ocean -- South Africa
- Description: As part of a long-term monitoring programme initiated by the South African Environmental Observation Network (SAEON) Elwandle Node, the spatio-temporal dynamics of mesozooplankton (200–2000 μm) community structure in Algoa Bay, on the Eastern Cape coastline of southern Africa, was investigated in summer and winter of 2008. Physical-chemical and biological variables were measured at selected sites in the eastern and western sectors of the Bay. During summer, nutrient rich waters upwelling into the eastern sector of the Bay contributed to significant spatial variation in selected physical-chemical variables. During winter, virtually no significant spatial patterns in the physical-chemical variables were observed (P>0.05 in all cases). For the majority of physical-chemical variables, no significant seasonal patterns in values were detected (P>0.05 in all cases). Notable exceptions were water column stability and water temperatures which were highest during summer, and seston, turbidity and ammonium concentrations which attained the highest values in winter. The striking seasonal pattern observed in the water column stability, coupled with the upwelling event, coincided with a strong seasonal pattern in the total surface and integrated chlorophyll-a concentrations within the Bay. During summer, the total surface phytoplankton biomass ranged from 1.87–3.11 μg.L⁻¹ and the integrated biomass values between 44.6 and 89.1 mg chl-a m⁻². In winter, surface chl-a concentrations ranged from 0.49 to 0.55 μg.L⁻¹ and integrated biomass from 13.5 to 13.8 mg chl-a m⁻². During both seasons, the large microphytoplankton (>20 μm) fraction contributed the most (>80%) to the total phytoplankton biomass suggesting that phytoplankton growth is not nutrient limited within the Bay. The total mesozooplankton abundance and biomass values during summer varied between 10088.92 and 28283.21 ind.m⁻³ and between 76.59 and 161.94 mg.m⁻³, respectively. During winter, total abundance and biomass of mesozooplankton within the Bay were significantly lower, ranging from 2392.49 to 11145.29 ind.m⁻³, and from 34.49 to 42.49 mg.m⁻³, respectively (P<0.05). During both seasons, cosmopolitan copepod species 200–500μm in size dominated the total mesozooplankton counts, numerically and in biomass. Hierarchical cluster analyses identified distinct zooplankton groupings within the Bay during both the summer (three groupings) and winter (four groupings) surveys. The different groupings identified during the two seasons were not associated with any specific geographic region or hydrological feature. Nonetheless, a distinct seasonal pattern in the mesozooplankton community was evident, largely reflecting the increased abundance of mesozooplankton during the summer survey. Canonical Correspondence Analyses (CCA) indicated that the zooplankton community structure within Algoa Bay reflected a complex interaction between physical-chemical (e.g. temperature, water column stability, turbidity, and nitrate, dissolved oxygen and nitrite concentrations) and biological factors (e.g. microphytoplankton and picophytoplankton concentrations). These data provide baseline information towards long-term monitoring programs that will be conducted in Algoa Bay, as part of the South African Environmental Observation Network (SAEON), in the near future.
- Full Text:
- Date Issued: 2011
- Authors: Dali, Luzuko O'Brian
- Date: 2011
- Subjects: Zooplankton -- Research -- Indian Ocean -- South Africa , Phytoplankton -- Research -- Indian Ocean -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5715 , http://hdl.handle.net/10962/d1005401 , Zooplankton -- Research -- Indian Ocean -- South Africa , Phytoplankton -- Research -- Indian Ocean -- South Africa
- Description: As part of a long-term monitoring programme initiated by the South African Environmental Observation Network (SAEON) Elwandle Node, the spatio-temporal dynamics of mesozooplankton (200–2000 μm) community structure in Algoa Bay, on the Eastern Cape coastline of southern Africa, was investigated in summer and winter of 2008. Physical-chemical and biological variables were measured at selected sites in the eastern and western sectors of the Bay. During summer, nutrient rich waters upwelling into the eastern sector of the Bay contributed to significant spatial variation in selected physical-chemical variables. During winter, virtually no significant spatial patterns in the physical-chemical variables were observed (P>0.05 in all cases). For the majority of physical-chemical variables, no significant seasonal patterns in values were detected (P>0.05 in all cases). Notable exceptions were water column stability and water temperatures which were highest during summer, and seston, turbidity and ammonium concentrations which attained the highest values in winter. The striking seasonal pattern observed in the water column stability, coupled with the upwelling event, coincided with a strong seasonal pattern in the total surface and integrated chlorophyll-a concentrations within the Bay. During summer, the total surface phytoplankton biomass ranged from 1.87–3.11 μg.L⁻¹ and the integrated biomass values between 44.6 and 89.1 mg chl-a m⁻². In winter, surface chl-a concentrations ranged from 0.49 to 0.55 μg.L⁻¹ and integrated biomass from 13.5 to 13.8 mg chl-a m⁻². During both seasons, the large microphytoplankton (>20 μm) fraction contributed the most (>80%) to the total phytoplankton biomass suggesting that phytoplankton growth is not nutrient limited within the Bay. The total mesozooplankton abundance and biomass values during summer varied between 10088.92 and 28283.21 ind.m⁻³ and between 76.59 and 161.94 mg.m⁻³, respectively. During winter, total abundance and biomass of mesozooplankton within the Bay were significantly lower, ranging from 2392.49 to 11145.29 ind.m⁻³, and from 34.49 to 42.49 mg.m⁻³, respectively (P<0.05). During both seasons, cosmopolitan copepod species 200–500μm in size dominated the total mesozooplankton counts, numerically and in biomass. Hierarchical cluster analyses identified distinct zooplankton groupings within the Bay during both the summer (three groupings) and winter (four groupings) surveys. The different groupings identified during the two seasons were not associated with any specific geographic region or hydrological feature. Nonetheless, a distinct seasonal pattern in the mesozooplankton community was evident, largely reflecting the increased abundance of mesozooplankton during the summer survey. Canonical Correspondence Analyses (CCA) indicated that the zooplankton community structure within Algoa Bay reflected a complex interaction between physical-chemical (e.g. temperature, water column stability, turbidity, and nitrate, dissolved oxygen and nitrite concentrations) and biological factors (e.g. microphytoplankton and picophytoplankton concentrations). These data provide baseline information towards long-term monitoring programs that will be conducted in Algoa Bay, as part of the South African Environmental Observation Network (SAEON), in the near future.
- Full Text:
- Date Issued: 2011
SphereZyme (TM) technology for enhanced enzyme immobilisation application in biosensors
- Authors: Molawa, Letshego Gloria
- Date: 2011
- Subjects: Immobilized enzymes , Hydrolases , Hydrolysis , SphereZyme , Biosensors , Proteolytic enzymes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3989 , http://hdl.handle.net/10962/d1004048 , Immobilized enzymes , Hydrolases , Hydrolysis , SphereZyme , Biosensors , Proteolytic enzymes
- Description: Self-immobilisation enzyme technologies, such as SphereZyme™, suffer from the lack of applicability to hydrolyse large substrates. Solid support immobilisation is usually a method of choice, to produce a stable biocatalyst for large substrates hydrolysis in the industry. In order to investigate this limitation, a commercial protease called Alcalase® was chosen as a model enzyme due to its natural activity (hydrolysis of large substrates-proteins). Prior to immobilising through the SphereZyme™ technology, Alcalase® was partially purified through dialysis followed by CM Sepharose™ FF cation exchanger. Sample contaminants, such as salts and stabilisers can inhibit protein crosslinking by reacting with glutaraldehyde. Alcalase® was successfully separated into 3 proteases with the major peak correlating to a positive control run on native PAGE, indicating that it was likely subtilisin Carlsberg. A 16% alkaline protease activity for azo-casein hydrolysis was retained when 5% v/v PEI: 25% v/v glutaraldehyde solution was used as a crosslinking agent in Alcalase® SphereZyme™ production. An increase in activity was also observed for monomeric substrates (PNPA) where the highest was 55%. The highest % activities maintained when 0.33 M EDA: 25% v/v glutaraldehyde solution was initially used as crosslinking agent were 4.5% and 1.6% for monomeric and polymeric substrates, respectively. PEI is a hydrophilic branched polymer with an abundance of amine groups compared to EDA. A comparison study of immobilisation efficiencies of SphereZyme™, Eupergit® and Dendrispheres was also performed for large substrate biocatalysis. The two latter technologies are solid-support immobilisation methods. Dendrispheres reached its maximum loading capacity in the first 5 minute of the one hour binding time. Twenty minutes was chosen as a maximum binding time since there was constant protein maintained on the solid support and no enzyme loss was observed during the 1 hour binding time. PEI at pH 11.5, its native pH, gave the highest immobilisation yield and specific activity over the PEI pH range of 11.5 to 7. SphereZyme™ had the highest ratio for azocasein hydrolysis followed by Dendrispheres and Eupergit®. The SphereZyme™ was also shown to be applicable to biosensors for phenol detection. Different modifications of glassy carbon electrode (GCE) were evaluated as a benchmark for the fabrication of SphereZyme™ modified phenol biosensor. GCE modified with laccase SphereZyme™ entrapped in cellulose membrane was the best modification due to the broad catechol range (<0.950 mM), high correlation coefficient (R2, 0.995) and relative high sensitivity factor (0.305 μA.mM-1). This type of biosensor was also shown to be electroactive at pH 7.0 for which its control, free laccase, lacked electroactivity. From the catalytic constants calculated, GCE modified with laccase SphereZyme™ entrapped in cellulose membrane also gave the highest effectiveness factor (Imax/Km app) of 1.84 μA.mM-1. The modified GCE with Alcalase® SphereZyme™ was relatively more sensitive than GCE modified with free Alcalase®.
- Full Text:
- Date Issued: 2011
- Authors: Molawa, Letshego Gloria
- Date: 2011
- Subjects: Immobilized enzymes , Hydrolases , Hydrolysis , SphereZyme , Biosensors , Proteolytic enzymes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3989 , http://hdl.handle.net/10962/d1004048 , Immobilized enzymes , Hydrolases , Hydrolysis , SphereZyme , Biosensors , Proteolytic enzymes
- Description: Self-immobilisation enzyme technologies, such as SphereZyme™, suffer from the lack of applicability to hydrolyse large substrates. Solid support immobilisation is usually a method of choice, to produce a stable biocatalyst for large substrates hydrolysis in the industry. In order to investigate this limitation, a commercial protease called Alcalase® was chosen as a model enzyme due to its natural activity (hydrolysis of large substrates-proteins). Prior to immobilising through the SphereZyme™ technology, Alcalase® was partially purified through dialysis followed by CM Sepharose™ FF cation exchanger. Sample contaminants, such as salts and stabilisers can inhibit protein crosslinking by reacting with glutaraldehyde. Alcalase® was successfully separated into 3 proteases with the major peak correlating to a positive control run on native PAGE, indicating that it was likely subtilisin Carlsberg. A 16% alkaline protease activity for azo-casein hydrolysis was retained when 5% v/v PEI: 25% v/v glutaraldehyde solution was used as a crosslinking agent in Alcalase® SphereZyme™ production. An increase in activity was also observed for monomeric substrates (PNPA) where the highest was 55%. The highest % activities maintained when 0.33 M EDA: 25% v/v glutaraldehyde solution was initially used as crosslinking agent were 4.5% and 1.6% for monomeric and polymeric substrates, respectively. PEI is a hydrophilic branched polymer with an abundance of amine groups compared to EDA. A comparison study of immobilisation efficiencies of SphereZyme™, Eupergit® and Dendrispheres was also performed for large substrate biocatalysis. The two latter technologies are solid-support immobilisation methods. Dendrispheres reached its maximum loading capacity in the first 5 minute of the one hour binding time. Twenty minutes was chosen as a maximum binding time since there was constant protein maintained on the solid support and no enzyme loss was observed during the 1 hour binding time. PEI at pH 11.5, its native pH, gave the highest immobilisation yield and specific activity over the PEI pH range of 11.5 to 7. SphereZyme™ had the highest ratio for azocasein hydrolysis followed by Dendrispheres and Eupergit®. The SphereZyme™ was also shown to be applicable to biosensors for phenol detection. Different modifications of glassy carbon electrode (GCE) were evaluated as a benchmark for the fabrication of SphereZyme™ modified phenol biosensor. GCE modified with laccase SphereZyme™ entrapped in cellulose membrane was the best modification due to the broad catechol range (<0.950 mM), high correlation coefficient (R2, 0.995) and relative high sensitivity factor (0.305 μA.mM-1). This type of biosensor was also shown to be electroactive at pH 7.0 for which its control, free laccase, lacked electroactivity. From the catalytic constants calculated, GCE modified with laccase SphereZyme™ entrapped in cellulose membrane also gave the highest effectiveness factor (Imax/Km app) of 1.84 μA.mM-1. The modified GCE with Alcalase® SphereZyme™ was relatively more sensitive than GCE modified with free Alcalase®.
- Full Text:
- Date Issued: 2011
Effects of habitat patch size and isolation on the population structure of two siphonarian limpets
- Authors: Johnson, Linda Gail
- Date: 2011
- Subjects: Siphonaria , Limpets , Population biology , Marine ecology , Habitat selection , Animals -- Dispersal , Ecological heterogeneity , Animal populations , Biodiversity
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5679 , http://hdl.handle.net/10962/d1005364 , Siphonaria , Limpets , Population biology , Marine ecology , Habitat selection , Animals -- Dispersal , Ecological heterogeneity , Animal populations , Biodiversity
- Description: Habitat fragmentation is a fundamental process that determines trends and patterns of distribution and density of organisms. These patterns and trends have been the focus of numerous terrestrial and marine studies and have led to the development of several explanatory hypotheses. Systems and organisms are dynamic and no single hypothesis has adequately accounted for these observed trends. It is therefore important to understand the interaction of these processes and patterns to explain the mechanisms controlling population dynamics. The main aim of this thesis was to test the effect of patch size and isolation on organisms with different modes of dispersal. Mode of dispersal has previously been examined as a factor influencing the effects that habitat fragmentation has on organisms. Very few studies have, however, examined the mode of dispersal of marine organisms because it has long been assumed that marine animals are not directly influenced by habitat fragmentation because of large-scale dispersal. I used two co-occurring species of siphonariid limpets with different modes of dispersal to highlight that not only are marine organisms affected by habitat fragmentation but that they are affected in different ways. The two species of limpet, Siphonaria serrata and Siphonaria concinna, are found within the same habitat and have the same geographic range along the South African coastline, however, they have different modes of dispersal and development. The effect of patch size on organism density has been examined to a great extent with varied results. This study investigated whether habitat patch size played a key role in determining population density and limpet body sizes. The two species are found on the eastern and southern coasts of South Africa were examined across this entire biogeographic range. Patch size was found to have a significant effect on population density of the pelagic developer, S. concinna, but not the direct developing S. serrata. Patch size did play a role in determining limpet body size for both species. S. concinna body size was proposed to be effected directly by patch size whilst S. serrata body size was proposed to be affected indirectly by the effects of the S. concinna densities. The same patterns and trends were observed at five of the seven examined regions across the biogeographic range. The trends observed for S. concinna with respect to patch size conform to the source-sink hypothesis with large habitat patches acting as the source populations whilst the small habitat patches acted as the sink populations. Many previous studies have focused on the effects of habitat patch size at one point in time or over one season. I tested the influence of habitat patch size on the two species of limpets over a period of twelve months to determine whether the trends observed were consistent over time or whether populations varied with time. S. concinna showed a consistently significant difference between small and large patches; whilst S. serrata did not follow a consistent pattern. The mode of dispersal for the two limpets was used to explain the different trends shown by the two species. This examination allowed for the determining of source and sink populations for S. concinna through the examination of fluctuations in limpet body sizes and population densities at small and large habitat patches over twelve months. The direct developing S. serrata trends could not be explained using source-sink theory, as populations were independent from one another. S. serrata demonstrated body size differences at small and large patches which, may be explained by interspecific and intraspecific competition. Habitat isolation is known to play an important role in determining the structure of assemblages and the densities of populations. In this study the population density of the pelagic developing S. concinna showed a weak influence of degree of isolation whilst that of the direct developing S. serrata did not, which may be because of habitat patches along the South African coastline not having great enough degrees of isolation. The population size-structure was influenced directly influenced by isolation for S. concinna, whilst the different population size structure for S. serrata may be explained by assemblage co-dependence. The mode of dispersal showed effects on the relationship of population density and population size-structure with habitat size and isolation. This study indicates the importance of investigating patterns and processes across a range of spatial and temporal scales to gain a comprehensive understanding of factors effecting intertidal organisms.
- Full Text:
- Date Issued: 2011
- Authors: Johnson, Linda Gail
- Date: 2011
- Subjects: Siphonaria , Limpets , Population biology , Marine ecology , Habitat selection , Animals -- Dispersal , Ecological heterogeneity , Animal populations , Biodiversity
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5679 , http://hdl.handle.net/10962/d1005364 , Siphonaria , Limpets , Population biology , Marine ecology , Habitat selection , Animals -- Dispersal , Ecological heterogeneity , Animal populations , Biodiversity
- Description: Habitat fragmentation is a fundamental process that determines trends and patterns of distribution and density of organisms. These patterns and trends have been the focus of numerous terrestrial and marine studies and have led to the development of several explanatory hypotheses. Systems and organisms are dynamic and no single hypothesis has adequately accounted for these observed trends. It is therefore important to understand the interaction of these processes and patterns to explain the mechanisms controlling population dynamics. The main aim of this thesis was to test the effect of patch size and isolation on organisms with different modes of dispersal. Mode of dispersal has previously been examined as a factor influencing the effects that habitat fragmentation has on organisms. Very few studies have, however, examined the mode of dispersal of marine organisms because it has long been assumed that marine animals are not directly influenced by habitat fragmentation because of large-scale dispersal. I used two co-occurring species of siphonariid limpets with different modes of dispersal to highlight that not only are marine organisms affected by habitat fragmentation but that they are affected in different ways. The two species of limpet, Siphonaria serrata and Siphonaria concinna, are found within the same habitat and have the same geographic range along the South African coastline, however, they have different modes of dispersal and development. The effect of patch size on organism density has been examined to a great extent with varied results. This study investigated whether habitat patch size played a key role in determining population density and limpet body sizes. The two species are found on the eastern and southern coasts of South Africa were examined across this entire biogeographic range. Patch size was found to have a significant effect on population density of the pelagic developer, S. concinna, but not the direct developing S. serrata. Patch size did play a role in determining limpet body size for both species. S. concinna body size was proposed to be effected directly by patch size whilst S. serrata body size was proposed to be affected indirectly by the effects of the S. concinna densities. The same patterns and trends were observed at five of the seven examined regions across the biogeographic range. The trends observed for S. concinna with respect to patch size conform to the source-sink hypothesis with large habitat patches acting as the source populations whilst the small habitat patches acted as the sink populations. Many previous studies have focused on the effects of habitat patch size at one point in time or over one season. I tested the influence of habitat patch size on the two species of limpets over a period of twelve months to determine whether the trends observed were consistent over time or whether populations varied with time. S. concinna showed a consistently significant difference between small and large patches; whilst S. serrata did not follow a consistent pattern. The mode of dispersal for the two limpets was used to explain the different trends shown by the two species. This examination allowed for the determining of source and sink populations for S. concinna through the examination of fluctuations in limpet body sizes and population densities at small and large habitat patches over twelve months. The direct developing S. serrata trends could not be explained using source-sink theory, as populations were independent from one another. S. serrata demonstrated body size differences at small and large patches which, may be explained by interspecific and intraspecific competition. Habitat isolation is known to play an important role in determining the structure of assemblages and the densities of populations. In this study the population density of the pelagic developing S. concinna showed a weak influence of degree of isolation whilst that of the direct developing S. serrata did not, which may be because of habitat patches along the South African coastline not having great enough degrees of isolation. The population size-structure was influenced directly influenced by isolation for S. concinna, whilst the different population size structure for S. serrata may be explained by assemblage co-dependence. The mode of dispersal showed effects on the relationship of population density and population size-structure with habitat size and isolation. This study indicates the importance of investigating patterns and processes across a range of spatial and temporal scales to gain a comprehensive understanding of factors effecting intertidal organisms.
- Full Text:
- Date Issued: 2011
Studies in South African marine molluscan chemistry
- Authors: Bromley, Candice Leigh
- Date: 2011
- Subjects: Mollusks -- South Africa , Marine invertebrates -- South Africa , Marine metabolites -- South Africa , Chemical oceanography -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4356 , http://hdl.handle.net/10962/d1005021
- Description: This thesis investigates the variability occurring in the secondary metabolites produced by three South African marine molluscs. Chapter Two discusses the isolation and spectroscopic structure elucidation of the metabolites isolated from two Siphonaria species. The re-investigation of Siphonaria capensis yielded siphonarienfuranone (2.2) as the only common polypropionate isolated from both the 1998 and 2009 collections of S. capensis from the same areas suggesting possible seasonal or genetic variation in polypropionate production. The sterol cholest-7-en-3,5,7- triol (2.33) was also isolated form the 2009 collection of S. capensis and this is the first time this compound has been isolated from a Siphonaria species. The second species, Siphonaria oculus is closely related to S. capensis and the investigation into the former’s secondary metaboliteproduction revealed 2.2 as a major metabolite suggesting an inter-species overlap in polypropionate production. Three new polypropionate metabolites, 2.35, 2.36 and 2.37 were also isolated from S. oculus. An unsuccessful attempt was made to establish the absolute configuration of 2.37 using the modified Mosher’s method and the limited amount of 2.37 available prevented any further attempts at resolving the absolute configuration of this compound. The 1H NMR analysis of the defensive mucus collected directly from S. oculus revealed the presence of the acyclic polypropionate 2.37 as a minor metabolite. The absence of characteristic signals for the furanone containing compounds 2.2, 2.35 and 2.36, might suggest that these compounds cyclise from a hypothetical acyclic precursor (2.38) during standard work up of bulk acetone extracts of Siphonaria species. Chapter Three discusses the re-isolation and spectroscopic structure elucidation of the metabolites isolated from the nudibranch, Leminda millecra. Three known natural products, millecrone A (3.1), 8-hydroxycalamenene (3.6) and cubebenone (3.8) were re-isolated from our 2010 collection of L. millecra, as well as the new minor metabolite 8-acetoxycalamenene (3.16). The cytotoxic prenylated toluquinones and toluhydroquinones (3.9-3.15) initially isolated from the 1998 collection of L. millecra were not found in the 2010 collection supporting the hypothesis that these compounds may be of fungal origin. L. millecra clearly shows variability in the compounds sequestered by this species with millecrone A (3.1) being the only common metabolite in the three investigations of L. millecra to date. An unsuccessful attempt was made to establish the absolute configuration of 3.1, 3.6 and 3.8 through initial LAH reduction of the ketone moiety contained in 3.1 and 3.8 and esterification of the resultant diastereomeric alcohol mixtures and the phenol functionality in 3.6 with (1S)-camphanic chloride. Crystallisation of the (S)- camphanate esters of 3.6 and 3.8 for X-ray analysis were unsuccessful, while the unexpected conjugate addition of a hydride in 3.1 resulted in complex diastereomeric mixtures which could not be separated by HPLC.
- Full Text:
- Date Issued: 2011
- Authors: Bromley, Candice Leigh
- Date: 2011
- Subjects: Mollusks -- South Africa , Marine invertebrates -- South Africa , Marine metabolites -- South Africa , Chemical oceanography -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4356 , http://hdl.handle.net/10962/d1005021
- Description: This thesis investigates the variability occurring in the secondary metabolites produced by three South African marine molluscs. Chapter Two discusses the isolation and spectroscopic structure elucidation of the metabolites isolated from two Siphonaria species. The re-investigation of Siphonaria capensis yielded siphonarienfuranone (2.2) as the only common polypropionate isolated from both the 1998 and 2009 collections of S. capensis from the same areas suggesting possible seasonal or genetic variation in polypropionate production. The sterol cholest-7-en-3,5,7- triol (2.33) was also isolated form the 2009 collection of S. capensis and this is the first time this compound has been isolated from a Siphonaria species. The second species, Siphonaria oculus is closely related to S. capensis and the investigation into the former’s secondary metaboliteproduction revealed 2.2 as a major metabolite suggesting an inter-species overlap in polypropionate production. Three new polypropionate metabolites, 2.35, 2.36 and 2.37 were also isolated from S. oculus. An unsuccessful attempt was made to establish the absolute configuration of 2.37 using the modified Mosher’s method and the limited amount of 2.37 available prevented any further attempts at resolving the absolute configuration of this compound. The 1H NMR analysis of the defensive mucus collected directly from S. oculus revealed the presence of the acyclic polypropionate 2.37 as a minor metabolite. The absence of characteristic signals for the furanone containing compounds 2.2, 2.35 and 2.36, might suggest that these compounds cyclise from a hypothetical acyclic precursor (2.38) during standard work up of bulk acetone extracts of Siphonaria species. Chapter Three discusses the re-isolation and spectroscopic structure elucidation of the metabolites isolated from the nudibranch, Leminda millecra. Three known natural products, millecrone A (3.1), 8-hydroxycalamenene (3.6) and cubebenone (3.8) were re-isolated from our 2010 collection of L. millecra, as well as the new minor metabolite 8-acetoxycalamenene (3.16). The cytotoxic prenylated toluquinones and toluhydroquinones (3.9-3.15) initially isolated from the 1998 collection of L. millecra were not found in the 2010 collection supporting the hypothesis that these compounds may be of fungal origin. L. millecra clearly shows variability in the compounds sequestered by this species with millecrone A (3.1) being the only common metabolite in the three investigations of L. millecra to date. An unsuccessful attempt was made to establish the absolute configuration of 3.1, 3.6 and 3.8 through initial LAH reduction of the ketone moiety contained in 3.1 and 3.8 and esterification of the resultant diastereomeric alcohol mixtures and the phenol functionality in 3.6 with (1S)-camphanic chloride. Crystallisation of the (S)- camphanate esters of 3.6 and 3.8 for X-ray analysis were unsuccessful, while the unexpected conjugate addition of a hydride in 3.1 resulted in complex diastereomeric mixtures which could not be separated by HPLC.
- Full Text:
- Date Issued: 2011
Expression of heat shock proteins on the plasma membrane of cancer cells : a potential multi-chaperone complex that mediates migration
- Authors: Kenyon, Amy
- Date: 2011 , 2011-03-29
- Subjects: Heat shock proteins , Protein folding , Molecular chaperones , Cancer -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4122 , http://hdl.handle.net/10962/d1013362
- Description: Current dogma suggests that the Heat Shock Protein (Hsp) molecular chaperones and associated co-chaperones function primarily within the cell, although growing evidence suggests a role for these proteins on the plasma membrane of cancer cells. Hsp90 does not function independently in vivo, but instead functions with a variety of partner chaperones and co-chaperones, that include Hsp70 and Hsp90/Hsp70 organising protein (Hop), which are thought to regulate ATP hydrolysis and the binding of Hsp90 to its client proteins. Hsp90 on the plasma membrane appears to have distinct roles in pathways leading to cell motility, invasion and metastasis. We hypothesised that Hsp90 on the plasma membrane is present as part of a multi-chaperone complex that participates in the chaperone-assisted folding of client membrane proteins in a manner analogous to the intracellular chaperone complex. This study characterised the membrane expression of Hsp90, Hsp70 and Hop in different cell models of different adhesive and migratory capacity, namely MDA-MB-231 (metastatic adherent breast cancer cell line), MCF-7 (non-metastatic adherent breast cancer cell line), U937 and THP1 (monocytic leukemia suspension cell lines). Membrane expression of the Hsps was analysed using a combination of subcellular fractionation, biotin-streptavidin affinity purification and immunofluorescence. This study provided evidence to suggest that Hsp90, Hsp70 and Hop are membrane associated in MDA-MB-231 and MCF-7 breast cancer cells. Hsp90, Hsp70 and Hop associated with the plasma membrane such that at least part of the protein is located extracellularly. Immunofluorescence analysis showed that Hsp90, Hsp70 and Hop at the leading edge may localize to membrane ruffles in MDA-MB-231 cells, in accordance with the published role of Hsp90 in migration. An increase in this response was seen in cells stimulated to migrate with SDF-1. By immunoprecipitation, we isolated a putative extracellular membrane associated complex containing Hsp90, Hsp70 and Hop. Using soluble Hsp90 and antibodies against membrane associated Hsp90, we suggested roles for soluble extracellular Hsp90 in mediating migration by wound healing assays and inducing actin reorganisation and vinculin-based focal adhesion formation. The effects of extracellular Hsp90 are mediated by signalling through an ERK1/2 dependent pathway. An anti-Hsp90 antibody against an N-terminal epitope in Hsp90 appeared to be able to overcome the death inducing effects of a combination of SDF-1 and AMD3100, while soluble Hsp90 could not overcome this effect. We propose that this study provides preliminary evidence that extracellular Hsp90 functions as part of a multi-chaperone complex that includes Hsp70 and Hop. The extracellular Hsp90 chaperone complex may mediate cell processes such as migration by modulating the conformation of cell surface receptors, leading to downstream signalling.
- Full Text:
- Date Issued: 2011
- Authors: Kenyon, Amy
- Date: 2011 , 2011-03-29
- Subjects: Heat shock proteins , Protein folding , Molecular chaperones , Cancer -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4122 , http://hdl.handle.net/10962/d1013362
- Description: Current dogma suggests that the Heat Shock Protein (Hsp) molecular chaperones and associated co-chaperones function primarily within the cell, although growing evidence suggests a role for these proteins on the plasma membrane of cancer cells. Hsp90 does not function independently in vivo, but instead functions with a variety of partner chaperones and co-chaperones, that include Hsp70 and Hsp90/Hsp70 organising protein (Hop), which are thought to regulate ATP hydrolysis and the binding of Hsp90 to its client proteins. Hsp90 on the plasma membrane appears to have distinct roles in pathways leading to cell motility, invasion and metastasis. We hypothesised that Hsp90 on the plasma membrane is present as part of a multi-chaperone complex that participates in the chaperone-assisted folding of client membrane proteins in a manner analogous to the intracellular chaperone complex. This study characterised the membrane expression of Hsp90, Hsp70 and Hop in different cell models of different adhesive and migratory capacity, namely MDA-MB-231 (metastatic adherent breast cancer cell line), MCF-7 (non-metastatic adherent breast cancer cell line), U937 and THP1 (monocytic leukemia suspension cell lines). Membrane expression of the Hsps was analysed using a combination of subcellular fractionation, biotin-streptavidin affinity purification and immunofluorescence. This study provided evidence to suggest that Hsp90, Hsp70 and Hop are membrane associated in MDA-MB-231 and MCF-7 breast cancer cells. Hsp90, Hsp70 and Hop associated with the plasma membrane such that at least part of the protein is located extracellularly. Immunofluorescence analysis showed that Hsp90, Hsp70 and Hop at the leading edge may localize to membrane ruffles in MDA-MB-231 cells, in accordance with the published role of Hsp90 in migration. An increase in this response was seen in cells stimulated to migrate with SDF-1. By immunoprecipitation, we isolated a putative extracellular membrane associated complex containing Hsp90, Hsp70 and Hop. Using soluble Hsp90 and antibodies against membrane associated Hsp90, we suggested roles for soluble extracellular Hsp90 in mediating migration by wound healing assays and inducing actin reorganisation and vinculin-based focal adhesion formation. The effects of extracellular Hsp90 are mediated by signalling through an ERK1/2 dependent pathway. An anti-Hsp90 antibody against an N-terminal epitope in Hsp90 appeared to be able to overcome the death inducing effects of a combination of SDF-1 and AMD3100, while soluble Hsp90 could not overcome this effect. We propose that this study provides preliminary evidence that extracellular Hsp90 functions as part of a multi-chaperone complex that includes Hsp70 and Hop. The extracellular Hsp90 chaperone complex may mediate cell processes such as migration by modulating the conformation of cell surface receptors, leading to downstream signalling.
- Full Text:
- Date Issued: 2011
Characterization of stratified L-topological spaces by convergence of stratified L-filters
- Authors: Orpen, David Lisle
- Date: 2011
- Subjects: Topology , Generalized spaces , Filters (Mathematics) , Topological spaces
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5402 , http://hdl.handle.net/10962/d1005216 , Topology , Generalized spaces , Filters (Mathematics) , Topological spaces
- Description: For the case where L is an ecl-premonoid, we explore various characterizations of SL-topological spaces, in particular characterization in terms of a convergence function lim: FS L(X) ! LX. We find we have to introduce a new axiom , L on the lim function in order to completely describe SL-topological spaces, which is not required in the case where L is a frame. We generalize the classical Kowalski and Fischer axioms to the lattice context and examine their relationship to the convergence axioms. We define the category of stratified L-generalized convergence spaces, as a generalization of the classical convergence spaces and investigate conditions under which it contains the category of stratified L-topological spaces as a reflective subcategory. We investigate some subcategories of the category of stratified L-generalized convergence spaces obtained by generalizing various classical convergence axioms.
- Full Text:
- Date Issued: 2011
- Authors: Orpen, David Lisle
- Date: 2011
- Subjects: Topology , Generalized spaces , Filters (Mathematics) , Topological spaces
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5402 , http://hdl.handle.net/10962/d1005216 , Topology , Generalized spaces , Filters (Mathematics) , Topological spaces
- Description: For the case where L is an ecl-premonoid, we explore various characterizations of SL-topological spaces, in particular characterization in terms of a convergence function lim: FS L(X) ! LX. We find we have to introduce a new axiom , L on the lim function in order to completely describe SL-topological spaces, which is not required in the case where L is a frame. We generalize the classical Kowalski and Fischer axioms to the lattice context and examine their relationship to the convergence axioms. We define the category of stratified L-generalized convergence spaces, as a generalization of the classical convergence spaces and investigate conditions under which it contains the category of stratified L-topological spaces as a reflective subcategory. We investigate some subcategories of the category of stratified L-generalized convergence spaces obtained by generalizing various classical convergence axioms.
- Full Text:
- Date Issued: 2011
Solid-phase extraction based sample preparation for the determination of drug and organic pollutant residue
- Authors: Pule, Bellah Oreeditse
- Date: 2011 , 2011-02-08
- Subjects: Food contamination , Drugs -- Analysis , Pharmaceutical chemistry , Extraction (Chemistry) , Sorbents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4406 , http://hdl.handle.net/10962/d1006711 , Food contamination , Drugs -- Analysis , Pharmaceutical chemistry , Extraction (Chemistry) , Sorbents
- Description: This thesis presents solid phase extraction (SPE) methodologies based on mixed-mode polymeric sorbents; a mixed mode strong anion exchanger (Agilent SampliQ SAX) and a mixed mode strong cation exchanger (Agilent SampliQ SCX). Furthermore, dispersive-SPE based on a quick, easy, cheap, effective, rugged and safe (QuEChERS) method was assessed for applicability in the determination of drug residues. The mixed-mode polymeric sorbents were evaluated for the simultaneous fractionation of drugs that exhibit diverse polarities with acidic, basic and neutral functionalities in biological matrices (plasma and urine). The polymeric skeleton of these sorbents entails an exchanger group and therefore provides two retention mechanisms, strong cation or anion exchange retention mechanisms with hydrophobic interactions. It was demonstrated that with a sequential elution protocol for sample clean-up analytes were fractionated into acidic, basic and neutral classes. The SAX was employed for analysis of ketoprofen, naproxen (acidic drugs), nortriptyline (basic) and secobarbital (neutral) from urine sample. The SCX was used for fractionating phenobarbital, p-toluamide (acidic), amphetamine, m-toluidine (basic) and acetaminophen (neutral drug) from plasma sample. QuEChERS method was employed for quantitative determination of 16 polycyclic aromatic hydrocarbons (PAHs) from fish fillets and soil; 9 sulfonamides (SAs) from chicken muscles and acrylamide (AA) in cooking oil. The analyte recoveries ranged from 79.6 - 109% with RSDs ranging from 0.06 - 1.9% at three different fortification levels. Good linearity (r2 > 0.9990) was attained for most analytes. The limits of detection and quantification ranged from 0.03 - 0.84 μg/ml and 0.81 - 1.89 μg/ml respectively for analytes in biological samples. LODs and LOQs for analytes in food and environmental samples ranged from 0.02 to 0.39 and 0.25 to 1.30 ng/g respectively.
- Full Text:
- Date Issued: 2011
- Authors: Pule, Bellah Oreeditse
- Date: 2011 , 2011-02-08
- Subjects: Food contamination , Drugs -- Analysis , Pharmaceutical chemistry , Extraction (Chemistry) , Sorbents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4406 , http://hdl.handle.net/10962/d1006711 , Food contamination , Drugs -- Analysis , Pharmaceutical chemistry , Extraction (Chemistry) , Sorbents
- Description: This thesis presents solid phase extraction (SPE) methodologies based on mixed-mode polymeric sorbents; a mixed mode strong anion exchanger (Agilent SampliQ SAX) and a mixed mode strong cation exchanger (Agilent SampliQ SCX). Furthermore, dispersive-SPE based on a quick, easy, cheap, effective, rugged and safe (QuEChERS) method was assessed for applicability in the determination of drug residues. The mixed-mode polymeric sorbents were evaluated for the simultaneous fractionation of drugs that exhibit diverse polarities with acidic, basic and neutral functionalities in biological matrices (plasma and urine). The polymeric skeleton of these sorbents entails an exchanger group and therefore provides two retention mechanisms, strong cation or anion exchange retention mechanisms with hydrophobic interactions. It was demonstrated that with a sequential elution protocol for sample clean-up analytes were fractionated into acidic, basic and neutral classes. The SAX was employed for analysis of ketoprofen, naproxen (acidic drugs), nortriptyline (basic) and secobarbital (neutral) from urine sample. The SCX was used for fractionating phenobarbital, p-toluamide (acidic), amphetamine, m-toluidine (basic) and acetaminophen (neutral drug) from plasma sample. QuEChERS method was employed for quantitative determination of 16 polycyclic aromatic hydrocarbons (PAHs) from fish fillets and soil; 9 sulfonamides (SAs) from chicken muscles and acrylamide (AA) in cooking oil. The analyte recoveries ranged from 79.6 - 109% with RSDs ranging from 0.06 - 1.9% at three different fortification levels. Good linearity (r2 > 0.9990) was attained for most analytes. The limits of detection and quantification ranged from 0.03 - 0.84 μg/ml and 0.81 - 1.89 μg/ml respectively for analytes in biological samples. LODs and LOQs for analytes in food and environmental samples ranged from 0.02 to 0.39 and 0.25 to 1.30 ng/g respectively.
- Full Text:
- Date Issued: 2011
The photophysical properties of low symmetry phthalocyanines in conjunction with quantum dots
- Authors: D'Souza, Sarah
- Date: 2011
- Subjects: Phthalocyanines , Photochemistry , Zinc , Quantum dots , Spectrum analysis , Nanoparticles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4331 , http://hdl.handle.net/10962/d1004992 , Phthalocyanines , Photochemistry , Zinc , Quantum dots , Spectrum analysis , Nanoparticles
- Description: he synthesis, extensive spectroscopic characterization and photophysical studies of low symmetry zinc phthalocyanine have been conducted. Comparisons have been made taking into consideration the influence of the solvent properties as well as substituent type and position. Photosensitizing properties of the zinc phthalocyanine derivatives in the presence of thiol capped CdTe quantum dots (QDs) were compared. The QDs were used as energy transfer donors and to facilitate with energy transfer through Förster resonance energy transfer (FRET) from the QDs to the MPcs. The linkage of unsymmetrically substituted 4-monoaminophenoxy zinc phthalocyanine (ZnAPPc) to CdTe quantum dots capped with mercaptopropionic acid (MPA), L-cysteine (L-cys) or thioglycolic acid (TGA) has been achieved using the coupling agents ethyl-N3 dimethylaminopropyl)carbodiimide (EDC) and N-hydroxy succinimide (NHS), which facilitate formation of an amide bond to form the QD-ZnAPPc-linked complex. The formation of the amide bond was confirmed using UV-Vis, Raman and IR spectroscopies, as well as AFM (atomic force microscopy). Förster resonance energy transfer (FRET) resulted in stimulated emission of ZnAPPc in both the linked (QDZnAPPc-linked) and mixed (QD:ZnAPPc-mixed) conjugates for MPA only. The linked L-cys and TGA complexes (QD-ZnAPPc-linked) gave the largest FRET efficiencies hence showing the advantages of covalent linking. Fluorescence quantum yields of QDs were decreased in QD:ZnAPPc-mixed and QD:ZnAPPc-linked. High triplet state quantum yields were obtained for the linked QD-phthalocyanine derivatives (ZnAPPc)and monoaminozinc phthalocyanine (ZnAPc) compared to when ZnAPPc and ZnAPc were mixed with MPA QDs without a chemical bond.
- Full Text:
- Date Issued: 2011
- Authors: D'Souza, Sarah
- Date: 2011
- Subjects: Phthalocyanines , Photochemistry , Zinc , Quantum dots , Spectrum analysis , Nanoparticles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4331 , http://hdl.handle.net/10962/d1004992 , Phthalocyanines , Photochemistry , Zinc , Quantum dots , Spectrum analysis , Nanoparticles
- Description: he synthesis, extensive spectroscopic characterization and photophysical studies of low symmetry zinc phthalocyanine have been conducted. Comparisons have been made taking into consideration the influence of the solvent properties as well as substituent type and position. Photosensitizing properties of the zinc phthalocyanine derivatives in the presence of thiol capped CdTe quantum dots (QDs) were compared. The QDs were used as energy transfer donors and to facilitate with energy transfer through Förster resonance energy transfer (FRET) from the QDs to the MPcs. The linkage of unsymmetrically substituted 4-monoaminophenoxy zinc phthalocyanine (ZnAPPc) to CdTe quantum dots capped with mercaptopropionic acid (MPA), L-cysteine (L-cys) or thioglycolic acid (TGA) has been achieved using the coupling agents ethyl-N3 dimethylaminopropyl)carbodiimide (EDC) and N-hydroxy succinimide (NHS), which facilitate formation of an amide bond to form the QD-ZnAPPc-linked complex. The formation of the amide bond was confirmed using UV-Vis, Raman and IR spectroscopies, as well as AFM (atomic force microscopy). Förster resonance energy transfer (FRET) resulted in stimulated emission of ZnAPPc in both the linked (QDZnAPPc-linked) and mixed (QD:ZnAPPc-mixed) conjugates for MPA only. The linked L-cys and TGA complexes (QD-ZnAPPc-linked) gave the largest FRET efficiencies hence showing the advantages of covalent linking. Fluorescence quantum yields of QDs were decreased in QD:ZnAPPc-mixed and QD:ZnAPPc-linked. High triplet state quantum yields were obtained for the linked QD-phthalocyanine derivatives (ZnAPPc)and monoaminozinc phthalocyanine (ZnAPc) compared to when ZnAPPc and ZnAPc were mixed with MPA QDs without a chemical bond.
- Full Text:
- Date Issued: 2011
Testing the existence and direction of "spill-over" of mussel recruits beyond the boundaries of marine protected areas
- Authors: Ludford, Adam
- Date: 2011
- Subjects: Marine parks and reserves -- South Africa -- Transkei , Marine resources conservation -- South Africa -- Transkei , Mussels -- Ecology -- South Africa -- Transkei , Mexilhao mussel -- Reproduction -- South Africa -- Transkei , Mexilhao mussel -- Behavior -- South Africa -- Transkei
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5786 , http://hdl.handle.net/10962/d1005474 , Marine parks and reserves -- South Africa -- Transkei , Marine resources conservation -- South Africa -- Transkei , Mussels -- Ecology -- South Africa -- Transkei , Mexilhao mussel -- Reproduction -- South Africa -- Transkei , Mexilhao mussel -- Behavior -- South Africa -- Transkei
- Description: Landscape ecology helps in predicting the influence of habitat fragmentation on populations. Marine protected areas (MPAs) are expected to create areas of good quality patches and so improve connectivity among shores. MPAs are believed not only to protect adult populations, but also to enhance recruitment both within MPAs and on surrounding exploited shores, therefore improving their ability to recover from overexploitation. As such, MPAs are a preferred management tool for the conservation of natural populations. Although MPAs have been demonstrated to enhance adult abundances, little work has been done on their ability to provide so called "spill-over" of recruits nor has the generality of the influence of MPAs been investigated in a single region with multiple control sites. The Transkei region, on the east coast of South Africa, and the intertidal mussel, Perna perna, offer an ideal system to test the generality of the influence of MPAs on surrounding shores, due to the presence of multiple MPAs and exploited control sites. Patterns of adult abundance were surveyed at four MPAs and two comparably sized exploited control sites. Adult abundances were, in general, found to be higher within MPAs than at exploited control sites, with adult abundances decreasing towards the edge of MPAs and decreasing even more on the outside shores. To simplify the sorting procedure for samples of mussel recruits, a new method using fractionated elutriation was devised and tested. This new method was found to be more accurate, although not statistically significant but also substantially more time consuming. The increase in accuracy although not statistically significant could be biologically significant, especially when looking at low numbers. This new method could, therefore, be very useful especially when [...] is low. Recruitment was estimated over three months during the main reproductive season at two of the MPAs and at appropriate control sites. I predicted that recruitment patterns would mirror the patterns found in adult abundances and that there would be directionality in patterns of recruitment, with northern sites having greater recruitment due to the direction of near-shore ocean currents. Contrary to this, there were no correlations between adult abundance and recruitment for any of the months or sites, with no clear spatial pattern of recruitment in any of the three months. There was, however, a slight trend of greater recruitment at northern sites. To explain the lack of consistency in recruitment and adult abundances, wind data were used to examine the near-shore surface currents in this area, with theoretical surface currents showing similar patterns to those observed for recruitment. From a landscape perspective, the good patches created by MPAs supply recruits to the surrounding matrix but the low quality of habitat in the matrix prevents rehabilitation. The quality of the matrix must therefore be first improved by reseeding these shores. These results emphasise that while MPAs may function in protecting adult abundances, their influence on supplying recruits and hence recovery of near-by exploited shores may be overestimated. This lack of influence on near-by exploited shores highlights the need for reseeding of shores in conjunction with suitable management plans.
- Full Text:
- Date Issued: 2011
- Authors: Ludford, Adam
- Date: 2011
- Subjects: Marine parks and reserves -- South Africa -- Transkei , Marine resources conservation -- South Africa -- Transkei , Mussels -- Ecology -- South Africa -- Transkei , Mexilhao mussel -- Reproduction -- South Africa -- Transkei , Mexilhao mussel -- Behavior -- South Africa -- Transkei
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5786 , http://hdl.handle.net/10962/d1005474 , Marine parks and reserves -- South Africa -- Transkei , Marine resources conservation -- South Africa -- Transkei , Mussels -- Ecology -- South Africa -- Transkei , Mexilhao mussel -- Reproduction -- South Africa -- Transkei , Mexilhao mussel -- Behavior -- South Africa -- Transkei
- Description: Landscape ecology helps in predicting the influence of habitat fragmentation on populations. Marine protected areas (MPAs) are expected to create areas of good quality patches and so improve connectivity among shores. MPAs are believed not only to protect adult populations, but also to enhance recruitment both within MPAs and on surrounding exploited shores, therefore improving their ability to recover from overexploitation. As such, MPAs are a preferred management tool for the conservation of natural populations. Although MPAs have been demonstrated to enhance adult abundances, little work has been done on their ability to provide so called "spill-over" of recruits nor has the generality of the influence of MPAs been investigated in a single region with multiple control sites. The Transkei region, on the east coast of South Africa, and the intertidal mussel, Perna perna, offer an ideal system to test the generality of the influence of MPAs on surrounding shores, due to the presence of multiple MPAs and exploited control sites. Patterns of adult abundance were surveyed at four MPAs and two comparably sized exploited control sites. Adult abundances were, in general, found to be higher within MPAs than at exploited control sites, with adult abundances decreasing towards the edge of MPAs and decreasing even more on the outside shores. To simplify the sorting procedure for samples of mussel recruits, a new method using fractionated elutriation was devised and tested. This new method was found to be more accurate, although not statistically significant but also substantially more time consuming. The increase in accuracy although not statistically significant could be biologically significant, especially when looking at low numbers. This new method could, therefore, be very useful especially when [...] is low. Recruitment was estimated over three months during the main reproductive season at two of the MPAs and at appropriate control sites. I predicted that recruitment patterns would mirror the patterns found in adult abundances and that there would be directionality in patterns of recruitment, with northern sites having greater recruitment due to the direction of near-shore ocean currents. Contrary to this, there were no correlations between adult abundance and recruitment for any of the months or sites, with no clear spatial pattern of recruitment in any of the three months. There was, however, a slight trend of greater recruitment at northern sites. To explain the lack of consistency in recruitment and adult abundances, wind data were used to examine the near-shore surface currents in this area, with theoretical surface currents showing similar patterns to those observed for recruitment. From a landscape perspective, the good patches created by MPAs supply recruits to the surrounding matrix but the low quality of habitat in the matrix prevents rehabilitation. The quality of the matrix must therefore be first improved by reseeding these shores. These results emphasise that while MPAs may function in protecting adult abundances, their influence on supplying recruits and hence recovery of near-by exploited shores may be overestimated. This lack of influence on near-by exploited shores highlights the need for reseeding of shores in conjunction with suitable management plans.
- Full Text:
- Date Issued: 2011
An investigation into the state-of-practice of information security within Zambian copper mines: a case study
- Authors: Lukweza, Chishala
- Date: 2011
- Subjects: Computer security -- Zambia -- Management Case studies , Computer networks -- Security measures -- Zambia Case studies , Copper mines and mining -- Computer networks -- Security measures -- Zambia Case studies , Information technology -- Zambia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:1146 , http://hdl.handle.net/10962/d1002776 , Computer security -- Zambia -- Management Case studies , Computer networks -- Security measures -- Zambia Case studies , Copper mines and mining -- Computer networks -- Security measures -- Zambia Case studies , Information technology -- Zambia
- Description: Zambian copper mines have embraced the use of information technologies for strategic operations and competitive advantage. This dependence on these technologies has not only been seen in the physical aspects of business operations but also in the use of information systems such as Enterprise Resource Planning Systems (ERPs) for strategic decision making and increased usage of Industrial Control Systems (ICS’) that are meant to enhance operational efficiency in production areas. A survey was conducted to explore leadership perceptions on information security practices in Zambian copper mines and an ISO/IEC 27002 Audit Tool was administered to middle management in a particular mine for an in-depth analysis of their information security practices. Results revealed that although information security controls may have been put in place in these organisations, there are still areas that require attention. Senior management and middle management have different perceptions as to the extent to which information security practices are conducted in these copper mines. This implies that management may not be fully involved in certain aspects of these organisations’ information security practices. The results concluded that management needs to be fully involved and provide support for information security programs. Furthermore, these information security programs should be standardised so as to effectively protect these organisations’ information assets. This should also include the involvement of personnel as key players in the information security process.
- Full Text:
- Date Issued: 2011
- Authors: Lukweza, Chishala
- Date: 2011
- Subjects: Computer security -- Zambia -- Management Case studies , Computer networks -- Security measures -- Zambia Case studies , Copper mines and mining -- Computer networks -- Security measures -- Zambia Case studies , Information technology -- Zambia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:1146 , http://hdl.handle.net/10962/d1002776 , Computer security -- Zambia -- Management Case studies , Computer networks -- Security measures -- Zambia Case studies , Copper mines and mining -- Computer networks -- Security measures -- Zambia Case studies , Information technology -- Zambia
- Description: Zambian copper mines have embraced the use of information technologies for strategic operations and competitive advantage. This dependence on these technologies has not only been seen in the physical aspects of business operations but also in the use of information systems such as Enterprise Resource Planning Systems (ERPs) for strategic decision making and increased usage of Industrial Control Systems (ICS’) that are meant to enhance operational efficiency in production areas. A survey was conducted to explore leadership perceptions on information security practices in Zambian copper mines and an ISO/IEC 27002 Audit Tool was administered to middle management in a particular mine for an in-depth analysis of their information security practices. Results revealed that although information security controls may have been put in place in these organisations, there are still areas that require attention. Senior management and middle management have different perceptions as to the extent to which information security practices are conducted in these copper mines. This implies that management may not be fully involved in certain aspects of these organisations’ information security practices. The results concluded that management needs to be fully involved and provide support for information security programs. Furthermore, these information security programs should be standardised so as to effectively protect these organisations’ information assets. This should also include the involvement of personnel as key players in the information security process.
- Full Text:
- Date Issued: 2011
Emplacement of the 2.44 Ga ultramafic layered Kemi intrusion, Finland PGE, geochemical and Sm-Nd isotopic implications
- Authors: Linkermann, Sean Aaron
- Date: 2011
- Subjects: Chromite -- Finland -- Kemi , Mining geology -- Finland -- Kemi , Geochemistry -- Finland -- Kemi , Petrology -- Finland -- Kemi
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4940 , http://hdl.handle.net/10962/d1005552 , Chromite -- Finland -- Kemi , Mining geology -- Finland -- Kemi , Geochemistry -- Finland -- Kemi , Petrology -- Finland -- Kemi
- Description: Europe’s largest chrome deposit is hosted by the 2.44 Ga Kemi ultramafic layered intrusion. The lower half of the intrusion consists of peridotites, pyroxenites and chromitite layers while the upper half consists of websterites, gabbronorites and leucogabbros. The mafic minerals of the lower and upper parts of the intrusion are altered to serpentine, chlorite, talc, amphiboles and carbonates. However, the original mineralogy is still preserved in the middle part of the intrusion. Earlier work on the Kemi intrusion concentrated mainly on the economically important chromitite layers and suggested that these layers were formed through contamination of a single pulse of primitive magma by underlying Archaean basement crustal material. The broad variations of the major element concentrations reflect variations in the mode of the Kemi rocks. The petrology, which shows olivine- and orthopyroxene-dominated rocks in the lower portion of the intrusion to plagioclase- and clinopyroxene-dominated rocks in the upper portion, shows a gross consistency with a fractional crystallization process.The incompatible elements are relatively enriched in the lower portion of the intrusion which is not consistent with a broad fractional crystallization process. These variations suggest that the ultramafic portion of the KemiIntrusion is relatively enriched in trapped liquid compared to the mafic portion.ε2.44 Nd values ranges from +4 (consistent with depleted mantle source) to -10 (indicating a contribution from Archaean crust). The lower peridotites, pyroxenites and websterites have ε2.44 Nd values ranging between depleted mantle signatures and -2, whereas the gabbroic cumulates have ε2.44 Nd values which cover a range from around -5 to -10. Nd isotopic variation in the lower part of the profile is punctuated by distinct spikes to lower ε2.44 Nd corresponding to the chromitite horizons. Both the lower and upper portions of the Kemi Intrusion show enrichment of LREEC1 relative to HREEC1. The LREEC1 enriched values start to increase markedly from about the 1000 meter mark and continue to increase in value towards the roof of the intrusion.The main enrichment of PGE (ΣPPGE = 55 to 148 ppb) occurs approximately 90 to 160 m above the basal contact, beginning within andcontinuing above the main chromitite ore horizon. The mantle-normalized PGE abundances of the main chromitite horizon and the peridotites and pyroxenites below it show enrichment of IPGEPM (Os + Ir + Ru) relative to PPGEPM (Rh + Pd + Pt). In contrast, the overlying rocks are characterised by enrichment of PPGEPM relative to IPGEPM. These PGE-patterns suggest the influence of two distinct controlling processes above and below the main chromitite reef.The isotopic data are consistent with the initial introduction of multiple pulses of depleted mantle-derived magma crystallising olivine and pyroxene. Before the parent magma was fed into the Kemi magma chamber, it underwent crustal contamination and assimilation in a staging chamber within the lower crust. Some of these pulses were “critically crustally contaminated”, inducing chromite saturation and precipitation. The modelling also predicts minor in-situ contamination of the parent magma in the Kemi chamber with its wall and roof rocks. Above the main chromitite layer (about 160 m above the basal contact), the chromite content decreases and the PPGEPM/IPGEPM values increase which is consistent with scavenging of the IPGE into the lowermost layers and/or evolving magma compositions. Above 1000 m, the isotopic and REE data indicate a new magma pulse which has also been extensively contaminated in the staging magma chamber before emplacement into the Kemi magma chamber. The contamination in the staging magma chamber increased which is reflected in a progressively larger crustal component towards the top of the Kemi Intrusion
- Full Text:
- Date Issued: 2011
- Authors: Linkermann, Sean Aaron
- Date: 2011
- Subjects: Chromite -- Finland -- Kemi , Mining geology -- Finland -- Kemi , Geochemistry -- Finland -- Kemi , Petrology -- Finland -- Kemi
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4940 , http://hdl.handle.net/10962/d1005552 , Chromite -- Finland -- Kemi , Mining geology -- Finland -- Kemi , Geochemistry -- Finland -- Kemi , Petrology -- Finland -- Kemi
- Description: Europe’s largest chrome deposit is hosted by the 2.44 Ga Kemi ultramafic layered intrusion. The lower half of the intrusion consists of peridotites, pyroxenites and chromitite layers while the upper half consists of websterites, gabbronorites and leucogabbros. The mafic minerals of the lower and upper parts of the intrusion are altered to serpentine, chlorite, talc, amphiboles and carbonates. However, the original mineralogy is still preserved in the middle part of the intrusion. Earlier work on the Kemi intrusion concentrated mainly on the economically important chromitite layers and suggested that these layers were formed through contamination of a single pulse of primitive magma by underlying Archaean basement crustal material. The broad variations of the major element concentrations reflect variations in the mode of the Kemi rocks. The petrology, which shows olivine- and orthopyroxene-dominated rocks in the lower portion of the intrusion to plagioclase- and clinopyroxene-dominated rocks in the upper portion, shows a gross consistency with a fractional crystallization process.The incompatible elements are relatively enriched in the lower portion of the intrusion which is not consistent with a broad fractional crystallization process. These variations suggest that the ultramafic portion of the KemiIntrusion is relatively enriched in trapped liquid compared to the mafic portion.ε2.44 Nd values ranges from +4 (consistent with depleted mantle source) to -10 (indicating a contribution from Archaean crust). The lower peridotites, pyroxenites and websterites have ε2.44 Nd values ranging between depleted mantle signatures and -2, whereas the gabbroic cumulates have ε2.44 Nd values which cover a range from around -5 to -10. Nd isotopic variation in the lower part of the profile is punctuated by distinct spikes to lower ε2.44 Nd corresponding to the chromitite horizons. Both the lower and upper portions of the Kemi Intrusion show enrichment of LREEC1 relative to HREEC1. The LREEC1 enriched values start to increase markedly from about the 1000 meter mark and continue to increase in value towards the roof of the intrusion.The main enrichment of PGE (ΣPPGE = 55 to 148 ppb) occurs approximately 90 to 160 m above the basal contact, beginning within andcontinuing above the main chromitite ore horizon. The mantle-normalized PGE abundances of the main chromitite horizon and the peridotites and pyroxenites below it show enrichment of IPGEPM (Os + Ir + Ru) relative to PPGEPM (Rh + Pd + Pt). In contrast, the overlying rocks are characterised by enrichment of PPGEPM relative to IPGEPM. These PGE-patterns suggest the influence of two distinct controlling processes above and below the main chromitite reef.The isotopic data are consistent with the initial introduction of multiple pulses of depleted mantle-derived magma crystallising olivine and pyroxene. Before the parent magma was fed into the Kemi magma chamber, it underwent crustal contamination and assimilation in a staging chamber within the lower crust. Some of these pulses were “critically crustally contaminated”, inducing chromite saturation and precipitation. The modelling also predicts minor in-situ contamination of the parent magma in the Kemi chamber with its wall and roof rocks. Above the main chromitite layer (about 160 m above the basal contact), the chromite content decreases and the PPGEPM/IPGEPM values increase which is consistent with scavenging of the IPGE into the lowermost layers and/or evolving magma compositions. Above 1000 m, the isotopic and REE data indicate a new magma pulse which has also been extensively contaminated in the staging magma chamber before emplacement into the Kemi magma chamber. The contamination in the staging magma chamber increased which is reflected in a progressively larger crustal component towards the top of the Kemi Intrusion
- Full Text:
- Date Issued: 2011
The role of Hsp90 in the Wnt pathway of MCF7 breast cancer cells
- Authors: Cooper, Leanne Claire
- Date: 2011
- Subjects: Cancer -- Treatment , Heat shock proteins , Cancer cells , Molecular chaperones
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3985 , http://hdl.handle.net/10962/d1004044 , Cancer -- Treatment , Heat shock proteins , Cancer cells , Molecular chaperones
- Description: Breast cancer is one of the most common forms of cancer in not only South African women, but women all over the world. The molecular chaperone heat shock protein 90 (HSP90) is upregulated in cancer and is almost exclusively associated with proteins involved in intracellular signal transduction, thus it plays an important role in signalling pathways within the cell. In cancer, there is an aberrant activation of the Wnt signaling pathway, which results in stabilized β-catenin being able to translocate to the nucleus where it can trigger the transcription of oncogenes found to be involved in the self-renewal of cells. The level of β-catenin is usually kept in check by a destruction complex comprising glycogen synthase kinase 3-beta (GSK-3β), axin1, adenomatous polyposis coli (APC) which phosphorylate β-catenin, resulting in its ubiquitination and degradation. HSP90 has been found to be associated with GSK-3β, but whether this association is only transient is debatable. Very little is known about the association of HSP90 with other members of the Wnt pathway in breast cancer. In this study, we have attempted to further identify the direct associations between HSP90 and GSK-3β, β-catenin, p-β-catenin and axin1. Immunofluorescence and confocal microscopy co-localization studies suggested a potential association between HSP90 and these proteins. Treatment with HSP90 inhibitors, 17-AAG and novobiocin resulted in a shift of axin1 to what appeared to be the plasma membrane. The associations of HSP90 with GSK-3β, β-catenin, p-β-catenin and axin1 were confirmed biochemically by co-immunoprecipitation and inhibition using 17-AAG, geldanamycin and novobiocin. We showed, for the first time that HSP90 is associated in a possible complex with β-catenin, p-β-catenin and axin1 therefore is potentially involved in the modulation of p-β-catenin in the Wnt pathway through the stabilization of the destruction complex.
- Full Text:
- Date Issued: 2011
- Authors: Cooper, Leanne Claire
- Date: 2011
- Subjects: Cancer -- Treatment , Heat shock proteins , Cancer cells , Molecular chaperones
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3985 , http://hdl.handle.net/10962/d1004044 , Cancer -- Treatment , Heat shock proteins , Cancer cells , Molecular chaperones
- Description: Breast cancer is one of the most common forms of cancer in not only South African women, but women all over the world. The molecular chaperone heat shock protein 90 (HSP90) is upregulated in cancer and is almost exclusively associated with proteins involved in intracellular signal transduction, thus it plays an important role in signalling pathways within the cell. In cancer, there is an aberrant activation of the Wnt signaling pathway, which results in stabilized β-catenin being able to translocate to the nucleus where it can trigger the transcription of oncogenes found to be involved in the self-renewal of cells. The level of β-catenin is usually kept in check by a destruction complex comprising glycogen synthase kinase 3-beta (GSK-3β), axin1, adenomatous polyposis coli (APC) which phosphorylate β-catenin, resulting in its ubiquitination and degradation. HSP90 has been found to be associated with GSK-3β, but whether this association is only transient is debatable. Very little is known about the association of HSP90 with other members of the Wnt pathway in breast cancer. In this study, we have attempted to further identify the direct associations between HSP90 and GSK-3β, β-catenin, p-β-catenin and axin1. Immunofluorescence and confocal microscopy co-localization studies suggested a potential association between HSP90 and these proteins. Treatment with HSP90 inhibitors, 17-AAG and novobiocin resulted in a shift of axin1 to what appeared to be the plasma membrane. The associations of HSP90 with GSK-3β, β-catenin, p-β-catenin and axin1 were confirmed biochemically by co-immunoprecipitation and inhibition using 17-AAG, geldanamycin and novobiocin. We showed, for the first time that HSP90 is associated in a possible complex with β-catenin, p-β-catenin and axin1 therefore is potentially involved in the modulation of p-β-catenin in the Wnt pathway through the stabilization of the destruction complex.
- Full Text:
- Date Issued: 2011
The effect of sewage effluent from De Beers marine diamond mining operations on the expression of cytochrome P450 (CYP1A) and vitellogenin (vtg)
- Authors: De Almeida, Louise
- Date: 2013-09-20
- Subjects: De Beers Consolidated Mines , Sewage disposal in rivers, lakes, etc. -- Namibia , Endocrine disrupting chemicals in water -- Namibia , Merluccius capensis -- Namibia , Merluccius -- Namibia , Water -- Pollution -- Namibia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4096 , http://hdl.handle.net/10962/d1009440 , De Beers Consolidated Mines , Sewage disposal in rivers, lakes, etc. -- Namibia , Endocrine disrupting chemicals in water -- Namibia , Merluccius capensis -- Namibia , Merluccius -- Namibia , Water -- Pollution -- Namibia
- Description: Sewage effluents disposed into the marine environment from De Beers Marine Namibia diamond mining vessels have the potential to cause endocrine disruptive effects in marine organisms. Endocrine disruption refers to the alteration of the normal functioning of the endocrine system and various chemicals have the ability to mimic hormones, effecting endogenous hormone synthesis, transport, receptor interaction and intracellular signaling. The potential endocrine disruptive effects, caused by the release of different types of sewage effluents into the ocean, on fish species is a concern due to the commercial importance of fish species found in the mining area e.g. hake, sole, horse mackerel. Increased awareness of marine environmental degradation due to the presence of chemical contaminants has resulted in research being done on early warning systems, in the form of biomarkers. Cytochrome P450 monooxygenase 1A (CYP1A) and vitellogenin (vtg) are important proteins found in fish liver and blood, that have been used as biomarkers for the detection of pollutants in fish. CYP1A is a subfamily of the P450 superfamily of enzymes and catalyzes the oxidation, hydrolysis and reduction of exogenous and endogenous compounds (phase I reactions) and thus has the capacity to regulate the metabolism of several organic contaminants. CYP1A expression is altered by exposure to planar xenobiotic compounds e.g. polyaromatic hydrocarbons. Vtg is an important precursor for egg yolk proteins and plays a role in the growth and development of an oocyte. Expression of this protein is altered upon exposure to estrogenic compounds. The aim of this project was to isolate CYP1A from fish liver by differential centrifugation and optimize conditions for the CYP1A-mediated ethoxyresorufin-Odeethylase (EROD) assay and western blot analysis (to assess CYP1A expression). Another aim of this study was to evaluate the potential effects of biologically disruptive chemicals from sewage effluents, discharged into the marine environment, on the expression of CYP1A in two species of hake, Merluccius capensis and M. paradoxus (Cape hake). CYP1A in Cape hake is approximately a 60 kDa protein and the highest EROD activity was detected in the microsomal fraction after differential centrifugation. Optimal EROD assay conditions were observed at pH 7.5, a temperature of 25 °C, 10 μl of sample and a reaction time of 30 seconds. Enzyme stability assays indicated a drastic decrease in enzyme activity after 30 seconds. The EROD assay was not NADPH dependent but was limited by NADPH supply, with an increase of 300% in EROD activity being observed with the addition of 0.1 M exogenous NADPH. The addition of dicumarol (40 μM), a phase II enzyme inhibitor, showed a 232% increase in EROD activity. This is because dicumarol inhibited enzymes with the capacity to metabolize the product (resorufin) of the EROD reaction. With regard to western blot analysis, the optimal primary (rabbit antifish CYP1A peptide) and secondary (anti-mouse/rabbit antibody-horseradish peroxidase conjugate (POD)) antibody dilutions were determined to be 1:1000 and 1:5000, respectively. The comparison of CYP1A expression in Cape hake samples from De Beers Marine mining area and reference sites showed higher EROD activity (16.29 ± 0.91 pmol/min) in fish samples from the mining area in comparison to the reference site (10.42 ± 2.65 pmol/min). Western blot analysis was in agreement with the EROD assay results and a higher CYP1A expression was observed in fish from the mining sites. The increased CYP1A expression observed in fish from the mining area is not definitively an indication of a pollutant effect in the environment, as several environmental and biological factors (e.g. photoperiod and age) must also be considered before reaching this conclusion. Another aim of this study was to purify vtg from Cape hake blood samples. Cape hake vtg was purified from fish plasma by selective precipitation with MgCl2 and EDTA. Precipitated sample was subjected to anion exchange chromatography using fast protein liquid chromatography (FPLC). Vtg eluted as two broad peaks and had a molecular weight above 200 kDa. SDS-PAGE analysis also resolved smaller molecular weight proteins below 70 kDa, which were thought to be vitellogenin cleavage proteins, lipovitellin and phosphovitins. Western blot analysis was performed; however, it did not produce any conclusive results. The purification of vtg enables further studies in characterizing this protein and developing assay aimed at detecting estrogenic pollutants in the marine environment
- Full Text:
- Authors: De Almeida, Louise
- Date: 2013-09-20
- Subjects: De Beers Consolidated Mines , Sewage disposal in rivers, lakes, etc. -- Namibia , Endocrine disrupting chemicals in water -- Namibia , Merluccius capensis -- Namibia , Merluccius -- Namibia , Water -- Pollution -- Namibia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4096 , http://hdl.handle.net/10962/d1009440 , De Beers Consolidated Mines , Sewage disposal in rivers, lakes, etc. -- Namibia , Endocrine disrupting chemicals in water -- Namibia , Merluccius capensis -- Namibia , Merluccius -- Namibia , Water -- Pollution -- Namibia
- Description: Sewage effluents disposed into the marine environment from De Beers Marine Namibia diamond mining vessels have the potential to cause endocrine disruptive effects in marine organisms. Endocrine disruption refers to the alteration of the normal functioning of the endocrine system and various chemicals have the ability to mimic hormones, effecting endogenous hormone synthesis, transport, receptor interaction and intracellular signaling. The potential endocrine disruptive effects, caused by the release of different types of sewage effluents into the ocean, on fish species is a concern due to the commercial importance of fish species found in the mining area e.g. hake, sole, horse mackerel. Increased awareness of marine environmental degradation due to the presence of chemical contaminants has resulted in research being done on early warning systems, in the form of biomarkers. Cytochrome P450 monooxygenase 1A (CYP1A) and vitellogenin (vtg) are important proteins found in fish liver and blood, that have been used as biomarkers for the detection of pollutants in fish. CYP1A is a subfamily of the P450 superfamily of enzymes and catalyzes the oxidation, hydrolysis and reduction of exogenous and endogenous compounds (phase I reactions) and thus has the capacity to regulate the metabolism of several organic contaminants. CYP1A expression is altered by exposure to planar xenobiotic compounds e.g. polyaromatic hydrocarbons. Vtg is an important precursor for egg yolk proteins and plays a role in the growth and development of an oocyte. Expression of this protein is altered upon exposure to estrogenic compounds. The aim of this project was to isolate CYP1A from fish liver by differential centrifugation and optimize conditions for the CYP1A-mediated ethoxyresorufin-Odeethylase (EROD) assay and western blot analysis (to assess CYP1A expression). Another aim of this study was to evaluate the potential effects of biologically disruptive chemicals from sewage effluents, discharged into the marine environment, on the expression of CYP1A in two species of hake, Merluccius capensis and M. paradoxus (Cape hake). CYP1A in Cape hake is approximately a 60 kDa protein and the highest EROD activity was detected in the microsomal fraction after differential centrifugation. Optimal EROD assay conditions were observed at pH 7.5, a temperature of 25 °C, 10 μl of sample and a reaction time of 30 seconds. Enzyme stability assays indicated a drastic decrease in enzyme activity after 30 seconds. The EROD assay was not NADPH dependent but was limited by NADPH supply, with an increase of 300% in EROD activity being observed with the addition of 0.1 M exogenous NADPH. The addition of dicumarol (40 μM), a phase II enzyme inhibitor, showed a 232% increase in EROD activity. This is because dicumarol inhibited enzymes with the capacity to metabolize the product (resorufin) of the EROD reaction. With regard to western blot analysis, the optimal primary (rabbit antifish CYP1A peptide) and secondary (anti-mouse/rabbit antibody-horseradish peroxidase conjugate (POD)) antibody dilutions were determined to be 1:1000 and 1:5000, respectively. The comparison of CYP1A expression in Cape hake samples from De Beers Marine mining area and reference sites showed higher EROD activity (16.29 ± 0.91 pmol/min) in fish samples from the mining area in comparison to the reference site (10.42 ± 2.65 pmol/min). Western blot analysis was in agreement with the EROD assay results and a higher CYP1A expression was observed in fish from the mining sites. The increased CYP1A expression observed in fish from the mining area is not definitively an indication of a pollutant effect in the environment, as several environmental and biological factors (e.g. photoperiod and age) must also be considered before reaching this conclusion. Another aim of this study was to purify vtg from Cape hake blood samples. Cape hake vtg was purified from fish plasma by selective precipitation with MgCl2 and EDTA. Precipitated sample was subjected to anion exchange chromatography using fast protein liquid chromatography (FPLC). Vtg eluted as two broad peaks and had a molecular weight above 200 kDa. SDS-PAGE analysis also resolved smaller molecular weight proteins below 70 kDa, which were thought to be vitellogenin cleavage proteins, lipovitellin and phosphovitins. Western blot analysis was performed; however, it did not produce any conclusive results. The purification of vtg enables further studies in characterizing this protein and developing assay aimed at detecting estrogenic pollutants in the marine environment
- Full Text: