Histological validation of gonadal macroscopic staging criteria for Labeo cylindricus (Pisces: Cyprinidae)
- Booth, Anthony J, Weyl, Olaf L F
- Authors: Booth, Anthony J , Weyl, Olaf L F
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124593 , vital:35634 , https://doi.org/10.1080/15627020.2000.11657094
- Description: Histological examination of gametogenesis revealed that the current staging criteria used to assess gonadal recrudescence of the redeye labeo, Labeo cylindricus, were adequate. Gametogenesis was qualitatively similar to that of freshwater teleosts with a clearly defined seasonal reproductive cycle. L. cylindricus undergoes seasonal gross morphological and cytological gonadal changes with previtellogenesis dominating during the winter, vitellogenic development during spring and summer culminating in large-scale spawning at the end of summer. Post-spawning mass atresia of oocytes was evident in autumn. The histological data presented support macroscopical evidence that L. cylindricus is a synchronous iteroparous spawner, reproducing over a short period each year throughout its life-span.
- Full Text:
- Date Issued: 2010
- Authors: Booth, Anthony J , Weyl, Olaf L F
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124593 , vital:35634 , https://doi.org/10.1080/15627020.2000.11657094
- Description: Histological examination of gametogenesis revealed that the current staging criteria used to assess gonadal recrudescence of the redeye labeo, Labeo cylindricus, were adequate. Gametogenesis was qualitatively similar to that of freshwater teleosts with a clearly defined seasonal reproductive cycle. L. cylindricus undergoes seasonal gross morphological and cytological gonadal changes with previtellogenesis dominating during the winter, vitellogenic development during spring and summer culminating in large-scale spawning at the end of summer. Post-spawning mass atresia of oocytes was evident in autumn. The histological data presented support macroscopical evidence that L. cylindricus is a synchronous iteroparous spawner, reproducing over a short period each year throughout its life-span.
- Full Text:
- Date Issued: 2010
Adult African sharptooth catfish, Clarias gariepinus, population dynamics in a small invaded warm-temperate impoundment
- Booth, Anthony J, Traas, Graham R L, Weyl, Olaf L F
- Authors: Booth, Anthony J , Traas, Graham R L , Weyl, Olaf L F
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123596 , vital:35461 , https://doi.10.3377/004.045.0208
- Description: African sharptooth catfish, Clarias gariepinus (Burchell 1822), is a potamodromous species that is naturally distributed from Turkey to the Orange River, South Africa (Skelton 1993). It is omnivorous, feeding on plankton, vegetation, invertebrates, carrion and fish (de Moor & Bruton 1988) and may exhibit pack-hunting behaviour when foraging for small fish (Bruton 1979; Merron 1993). Clarias gariepinus is a large (>150 cm TL, >30 kg; Bruton 1976), long-lived (validated to at least 15 years, Weyl & Booth 2008) and fast-growing (Bruton & Allanson 1980; Quick & Bruton 1984; Richardson et al. 2009) fish that attains sexual maturity within two years of age (de Moor & Bruton 1988). It is eurythermic (80–35°C), mesohalic (0–10 ppt) and has the ability to airbreathe. These attributes predispose it to surviving in all but the most adverse of conditions and have directly contributed to its wide use as an aquaculture species. These attributes have also contributed to its ability to invade waterbodies beyond its natural range (de Moor & Bruton 1988) and after inadvertent introductions such as by escape from aquaculture facilities or through water transfer schemes, C. gariepinus has established populations in many non-native environments. Such invasions include the Philippines (Mercene 1997), Bangladesh (Arthur & Ahmed 2002), Thailand (Vidthayanon 2005), India (Bhakta & Bandyopadhyay 2007) and Brazil (Cambray 2005; Vitule et al. 2006; Rocha & Schiavetti 2007). In South Africa, C. gariepinus invaded the temperate Great Fish River catchment after the species was translocated from the Orange River through a Interbasin Water Transfer (IBWT) scheme (Laurenson et al. 1989). Potential threats include predation of and competition with indigenous species, habitat degradation, and the spread of diseases and parasites (Dudgeon et al. 2006).
- Full Text:
- Date Issued: 2010
- Authors: Booth, Anthony J , Traas, Graham R L , Weyl, Olaf L F
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123596 , vital:35461 , https://doi.10.3377/004.045.0208
- Description: African sharptooth catfish, Clarias gariepinus (Burchell 1822), is a potamodromous species that is naturally distributed from Turkey to the Orange River, South Africa (Skelton 1993). It is omnivorous, feeding on plankton, vegetation, invertebrates, carrion and fish (de Moor & Bruton 1988) and may exhibit pack-hunting behaviour when foraging for small fish (Bruton 1979; Merron 1993). Clarias gariepinus is a large (>150 cm TL, >30 kg; Bruton 1976), long-lived (validated to at least 15 years, Weyl & Booth 2008) and fast-growing (Bruton & Allanson 1980; Quick & Bruton 1984; Richardson et al. 2009) fish that attains sexual maturity within two years of age (de Moor & Bruton 1988). It is eurythermic (80–35°C), mesohalic (0–10 ppt) and has the ability to airbreathe. These attributes predispose it to surviving in all but the most adverse of conditions and have directly contributed to its wide use as an aquaculture species. These attributes have also contributed to its ability to invade waterbodies beyond its natural range (de Moor & Bruton 1988) and after inadvertent introductions such as by escape from aquaculture facilities or through water transfer schemes, C. gariepinus has established populations in many non-native environments. Such invasions include the Philippines (Mercene 1997), Bangladesh (Arthur & Ahmed 2002), Thailand (Vidthayanon 2005), India (Bhakta & Bandyopadhyay 2007) and Brazil (Cambray 2005; Vitule et al. 2006; Rocha & Schiavetti 2007). In South Africa, C. gariepinus invaded the temperate Great Fish River catchment after the species was translocated from the Orange River through a Interbasin Water Transfer (IBWT) scheme (Laurenson et al. 1989). Potential threats include predation of and competition with indigenous species, habitat degradation, and the spread of diseases and parasites (Dudgeon et al. 2006).
- Full Text:
- Date Issued: 2010
A histological description of ovarian recrudescence in two Labeo victorianus populations
- Booth, Anthony J, Hecht, Thomas
- Authors: Booth, Anthony J , Hecht, Thomas
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123564 , vital:35455 , https://doi.org/10.2989/16085910409503813
- Description: The ovaries of Labeo victorianus are paired organs situated in the peritoneal cavity and suspended on either side of the midline by a mesovarium. A capsule, composed of dense, regularly-arranged collagen and elastic fibres mixed with a few smooth muscle cells, enclosed the ovaries and gave off connective tissue septa, forming the ovigerous lamellae, which contained germ and follicle cells. Eight discrete stages of recrudescence were identified: oogonia, chromatin nucleolar oocytes, perinucleolar oocytes, primary yolk vesicle oocytes, secondary yolk vesicle oocytes, tertiary yolk vesicle oocytes, post-ovulatory follicles and atretic oocytes. Ovulation seemed to be synchronised with the onset of rainfall, with some deviations in the Sio River population. Gonadosomatic index variation followed a bimodal pattern, with maxima between January–February and between September–October for both populations. The same pattern was exhibited for both rainfall and water levels at the two study sites. Successful ovulation was followed by the formation of post-ovulatory follicles and Type I atresia, while failed spawning was characterised by Type II atresia. Clearance of post-ovulatory follicles was by phagocytosis and formation of melanomacrophage centres. There were variations in post-ovulatory changes between the two populations. Reproductive patterns in the Kagera River population conformed to the ‘norm’ in African labeines of the synchronisation of spawning with rainfall. Slight deviations from this pattern were, however, observed in the Sio River population where spawning occurred prior to the onset of rainfall.
- Full Text:
- Date Issued: 2010
- Authors: Booth, Anthony J , Hecht, Thomas
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123564 , vital:35455 , https://doi.org/10.2989/16085910409503813
- Description: The ovaries of Labeo victorianus are paired organs situated in the peritoneal cavity and suspended on either side of the midline by a mesovarium. A capsule, composed of dense, regularly-arranged collagen and elastic fibres mixed with a few smooth muscle cells, enclosed the ovaries and gave off connective tissue septa, forming the ovigerous lamellae, which contained germ and follicle cells. Eight discrete stages of recrudescence were identified: oogonia, chromatin nucleolar oocytes, perinucleolar oocytes, primary yolk vesicle oocytes, secondary yolk vesicle oocytes, tertiary yolk vesicle oocytes, post-ovulatory follicles and atretic oocytes. Ovulation seemed to be synchronised with the onset of rainfall, with some deviations in the Sio River population. Gonadosomatic index variation followed a bimodal pattern, with maxima between January–February and between September–October for both populations. The same pattern was exhibited for both rainfall and water levels at the two study sites. Successful ovulation was followed by the formation of post-ovulatory follicles and Type I atresia, while failed spawning was characterised by Type II atresia. Clearance of post-ovulatory follicles was by phagocytosis and formation of melanomacrophage centres. There were variations in post-ovulatory changes between the two populations. Reproductive patterns in the Kagera River population conformed to the ‘norm’ in African labeines of the synchronisation of spawning with rainfall. Slight deviations from this pattern were, however, observed in the Sio River population where spawning occurred prior to the onset of rainfall.
- Full Text:
- Date Issued: 2010
The gap between what 'ought' to be and what students want
- Authors: Boshoff, Priscilla A
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/70812 , vital:29747
- Description: There’s no curriculum! There’s no curriculum!” The young man in the focus group was so frustrated that he had to repeat himself, not just once, but several times. I had just asked the group what their feelings were about their second-year coursework. His sentiments were echoed by many of the students in the group, all of whom had passed the rigorous application process into second year at Rhodes University’s School of Journalism and Media Studies.
- Full Text:
- Date Issued: 2010
- Authors: Boshoff, Priscilla A
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/70812 , vital:29747
- Description: There’s no curriculum! There’s no curriculum!” The young man in the focus group was so frustrated that he had to repeat himself, not just once, but several times. I had just asked the group what their feelings were about their second-year coursework. His sentiments were echoed by many of the students in the group, all of whom had passed the rigorous application process into second year at Rhodes University’s School of Journalism and Media Studies.
- Full Text:
- Date Issued: 2010
How can educators in the intermediate phase be empowered to cope with the demands they face in an inclusive classroom situation?
- Authors: Bosman, Ysanne Bosman
- Date: 2010
- Subjects: Learning disabilities , Children with disabilities -- Education (Elementary) , Inclusive education , Teachers of problem children , Classroom management , Special education teachers -- Training of , Teachers -- Uganda
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9507 , http://hdl.handle.net/10948/1234 , Learning disabilities , Children with disabilities -- Education (Elementary) , Inclusive education , Teachers of problem children , Classroom management , Special education teachers -- Training of , Teachers -- Uganda
- Description: The rationale of my research was to make sure that all learners are treated as equals in the education afforded to them. The researcher noticed that not all educators in mainstream schools facing learners experiencing learning problems could deal with the Curriculum and that many had difficulty in coping in an inclusive classrooms setting. Furthermore, the researcher noticed that many educators percieve that they did not have the knowledge and skills to identify and support learners experiencing learning problems. Consequently, the educators felt that they could not effectively help these learners in their learning progress. While the educators struggle to cope, learners ended up having to repeat a grade or being promoted to the next grade without having attained the neccesary skills yet. The researcher set out to research what the available literature stated about how educators could be empowered to cope with teaching learners experiencing learning problems in an inclusive classroom situation. For this research study, a qualitative approach was followed, as it best matched the type of interactive investigation considered necessary. Due to time, financial and resources constraints, purpose sampling was used as the most effective method of yielding data. The qualitative approach embraced a multi-perspective approach, in terms of which methods of data collection were used, such as collection questionnaires, conducting interviews and using observations. The researcher trusts that her understanding as presented in the research findings and the recommendations made will benefit not only herself, but will empower all educators coping with the stress of teaching learners experiencing learning problems and improving their skills and self-esteem in the educational environment.
- Full Text:
- Date Issued: 2010
- Authors: Bosman, Ysanne Bosman
- Date: 2010
- Subjects: Learning disabilities , Children with disabilities -- Education (Elementary) , Inclusive education , Teachers of problem children , Classroom management , Special education teachers -- Training of , Teachers -- Uganda
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9507 , http://hdl.handle.net/10948/1234 , Learning disabilities , Children with disabilities -- Education (Elementary) , Inclusive education , Teachers of problem children , Classroom management , Special education teachers -- Training of , Teachers -- Uganda
- Description: The rationale of my research was to make sure that all learners are treated as equals in the education afforded to them. The researcher noticed that not all educators in mainstream schools facing learners experiencing learning problems could deal with the Curriculum and that many had difficulty in coping in an inclusive classrooms setting. Furthermore, the researcher noticed that many educators percieve that they did not have the knowledge and skills to identify and support learners experiencing learning problems. Consequently, the educators felt that they could not effectively help these learners in their learning progress. While the educators struggle to cope, learners ended up having to repeat a grade or being promoted to the next grade without having attained the neccesary skills yet. The researcher set out to research what the available literature stated about how educators could be empowered to cope with teaching learners experiencing learning problems in an inclusive classroom situation. For this research study, a qualitative approach was followed, as it best matched the type of interactive investigation considered necessary. Due to time, financial and resources constraints, purpose sampling was used as the most effective method of yielding data. The qualitative approach embraced a multi-perspective approach, in terms of which methods of data collection were used, such as collection questionnaires, conducting interviews and using observations. The researcher trusts that her understanding as presented in the research findings and the recommendations made will benefit not only herself, but will empower all educators coping with the stress of teaching learners experiencing learning problems and improving their skills and self-esteem in the educational environment.
- Full Text:
- Date Issued: 2010
Motivation and complexity : an exploration of a complexity approach in employee motivation with specific focus on a Lacanian model of desire
- Authors: Botha, Anton Ivan
- Date: 2010
- Subjects: Employee motivation , Employee morale , Incentive awards
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:9400 , http://hdl.handle.net/10948/1232 , Employee motivation , Employee morale , Incentive awards
- Description: Since employee motivation contributes to overall organisational success, reliable motivation theory should inform management and reward practices. Yet, motivation theory is currently in a state of paralysis, with no constructive theorising taking place. Analysis of its methodological presuppositions reveals that it relies on out-dated binary thinking, prioritising, e.g. either a ‘machine-like’ (body driven) or ‘god-like’ (rationally driven) understanding of humanity. In this study it is argued that the revival of motivation theory requires a paradigmatic shift towards a complexity methodology because human motivation was found to be a complex system and must be theorised accordingly. It was found that McAdams’ theory of personality which brought together personality traits, conditioning, and motives could form the basis of a complex theory of motivation. On this basis, a complex model was developed which incorporated elements of existing motivational theories. This model proposed that drives, which motivate behaviour, are a combination of instincts, needs, and desires, mediated by personality traits, rational processing, and conditioning. All of these interconnected elements, as well as biological and environmental conditions, have an impact on, and are influenced by one another. For the purposes of understanding employee motivation the element of desire was isolated as a potential means to value segment employees. A Lacanian theory was utilised to elaborate on the element of desire. This theory postulated that individuals tend to display a dominance is one of nine kinds and modes of desire. An instrument was developed to test the applicability of the Lacanian model. It was developed in five phases which included three pilot studies and two samplings. A total of 591 respondents participated in the empirical research study with 428 in the first sample and 70 in the second; the remaining 93 made up the pilot studies. Unlike the initial version of the instrument used in the first sample (n=428) the data obtained by the last version (n=70) revealed that the instrument held some form of reliability and validity. Once analysed through descriptive and inferential statistics the data supported the view that individuals tended to display dominance in a kind and mode of desire as per the Lacanian model, and sufficient variance existed to preliminarily conclude that this model could be used as a means to value segment employees. Recommendations were as follows: (1) that complexity methodology should inform future motivation theorising, (2) that the proposed complexity models be further empirically tested, (3) that an adequately complex, flexible rewards system be considered, (4) that both managers and employees make use of the developed instrument to aid them in the selection of rewards that will lead to increased satisfaction.
- Full Text:
- Date Issued: 2010
- Authors: Botha, Anton Ivan
- Date: 2010
- Subjects: Employee motivation , Employee morale , Incentive awards
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:9400 , http://hdl.handle.net/10948/1232 , Employee motivation , Employee morale , Incentive awards
- Description: Since employee motivation contributes to overall organisational success, reliable motivation theory should inform management and reward practices. Yet, motivation theory is currently in a state of paralysis, with no constructive theorising taking place. Analysis of its methodological presuppositions reveals that it relies on out-dated binary thinking, prioritising, e.g. either a ‘machine-like’ (body driven) or ‘god-like’ (rationally driven) understanding of humanity. In this study it is argued that the revival of motivation theory requires a paradigmatic shift towards a complexity methodology because human motivation was found to be a complex system and must be theorised accordingly. It was found that McAdams’ theory of personality which brought together personality traits, conditioning, and motives could form the basis of a complex theory of motivation. On this basis, a complex model was developed which incorporated elements of existing motivational theories. This model proposed that drives, which motivate behaviour, are a combination of instincts, needs, and desires, mediated by personality traits, rational processing, and conditioning. All of these interconnected elements, as well as biological and environmental conditions, have an impact on, and are influenced by one another. For the purposes of understanding employee motivation the element of desire was isolated as a potential means to value segment employees. A Lacanian theory was utilised to elaborate on the element of desire. This theory postulated that individuals tend to display a dominance is one of nine kinds and modes of desire. An instrument was developed to test the applicability of the Lacanian model. It was developed in five phases which included three pilot studies and two samplings. A total of 591 respondents participated in the empirical research study with 428 in the first sample and 70 in the second; the remaining 93 made up the pilot studies. Unlike the initial version of the instrument used in the first sample (n=428) the data obtained by the last version (n=70) revealed that the instrument held some form of reliability and validity. Once analysed through descriptive and inferential statistics the data supported the view that individuals tended to display dominance in a kind and mode of desire as per the Lacanian model, and sufficient variance existed to preliminarily conclude that this model could be used as a means to value segment employees. Recommendations were as follows: (1) that complexity methodology should inform future motivation theorising, (2) that the proposed complexity models be further empirically tested, (3) that an adequately complex, flexible rewards system be considered, (4) that both managers and employees make use of the developed instrument to aid them in the selection of rewards that will lead to increased satisfaction.
- Full Text:
- Date Issued: 2010
Nest site fidelity and nest site selection of loggerhead, Caretta Caretta, and leatherback, dermochelys coriacea, turtles in KwaZulu-Natal, South Africa
- Authors: Botha, Marié
- Date: 2010
- Subjects: Sea turtles -- South Africa -- KwaZulu-Natal , Loggerhead turtle -- South Africa -- KwaZulu-Natal , Leatherback turtle -- South Africa -- KwaZulu-Natal , Nest building , Turtles -- Habitat
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10696 , http://hdl.handle.net/10948/1233 , Sea turtles -- South Africa -- KwaZulu-Natal , Loggerhead turtle -- South Africa -- KwaZulu-Natal , Leatherback turtle -- South Africa -- KwaZulu-Natal , Nest building , Turtles -- Habitat
- Description: Loggerhead and leatherback sea turtles nest on the beaches of the north-eastern portion of Kwazulu-Natal within the iSimangaliso Wetland Park. Loggerheads place ~60 percent of all nests within an 8 km stretch of beach, whereas leatherbacks tend to space their nests more evenly along the entire length of the monitoring area. The study aimed to determine nest site fidelity of loggerheads and leatherbacks (using four decades of nesting data housed by Ezemvelo KZN Wildlife) and the factors that influence nest site selection of both species within the 56 km of turtle monitoring area (32N to 100S) and the 5 km area of high-density loggerhead nesting (0N to 12N). The effectiveness of nest site selection was then determined through the hatching success of loggerheads over the 5km area (0N to 12N). Results showed that loggerheads show a high degree of nest site fidelity (~3 km) with nest site fidelity of individuals increasing over subsequent seasons of nesting, as well as these individuals using the same stretches of beach for nesting (the most popular area being 1N to 4N for repeat nesters). Leatherbacks displayed nest site fidelity of ~9 km and this did not increase over successive seasons of nesting. In terms of nest site selection, loggerheads and leatherbacks both avoided areas where low shore rock was present, whereas both species preferred nesting on beaches of intermediate morphodynamic state. Leatherback nesting was significantly higher in areas with wider surf zones. Both species were able to surpass the high water mark when nesting as nests below this point would be almost certainly doomed. Hatching success of loggerheads was comparative to high (83 %) relative to other studies, however, nest success varied across the beach from beacon 1N to 12N. Areas where highest nest success was observed were not areas of highest nest density presumably due to artificial lighting. Results from this study increase our understanding of the evolutionary biology of loggerhead and leatherback turtles in South Africa and the effectiveness of loggerhead nest site selection through hatching success.
- Full Text:
- Date Issued: 2010
- Authors: Botha, Marié
- Date: 2010
- Subjects: Sea turtles -- South Africa -- KwaZulu-Natal , Loggerhead turtle -- South Africa -- KwaZulu-Natal , Leatherback turtle -- South Africa -- KwaZulu-Natal , Nest building , Turtles -- Habitat
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10696 , http://hdl.handle.net/10948/1233 , Sea turtles -- South Africa -- KwaZulu-Natal , Loggerhead turtle -- South Africa -- KwaZulu-Natal , Leatherback turtle -- South Africa -- KwaZulu-Natal , Nest building , Turtles -- Habitat
- Description: Loggerhead and leatherback sea turtles nest on the beaches of the north-eastern portion of Kwazulu-Natal within the iSimangaliso Wetland Park. Loggerheads place ~60 percent of all nests within an 8 km stretch of beach, whereas leatherbacks tend to space their nests more evenly along the entire length of the monitoring area. The study aimed to determine nest site fidelity of loggerheads and leatherbacks (using four decades of nesting data housed by Ezemvelo KZN Wildlife) and the factors that influence nest site selection of both species within the 56 km of turtle monitoring area (32N to 100S) and the 5 km area of high-density loggerhead nesting (0N to 12N). The effectiveness of nest site selection was then determined through the hatching success of loggerheads over the 5km area (0N to 12N). Results showed that loggerheads show a high degree of nest site fidelity (~3 km) with nest site fidelity of individuals increasing over subsequent seasons of nesting, as well as these individuals using the same stretches of beach for nesting (the most popular area being 1N to 4N for repeat nesters). Leatherbacks displayed nest site fidelity of ~9 km and this did not increase over successive seasons of nesting. In terms of nest site selection, loggerheads and leatherbacks both avoided areas where low shore rock was present, whereas both species preferred nesting on beaches of intermediate morphodynamic state. Leatherback nesting was significantly higher in areas with wider surf zones. Both species were able to surpass the high water mark when nesting as nests below this point would be almost certainly doomed. Hatching success of loggerheads was comparative to high (83 %) relative to other studies, however, nest success varied across the beach from beacon 1N to 12N. Areas where highest nest success was observed were not areas of highest nest density presumably due to artificial lighting. Results from this study increase our understanding of the evolutionary biology of loggerhead and leatherback turtles in South Africa and the effectiveness of loggerhead nest site selection through hatching success.
- Full Text:
- Date Issued: 2010
The in vitro biological activities of three Hypoxis species and their active compounds
- Authors: Boukes, Gerhardt Johannes
- Date: 2010
- Subjects: Potatoes -- Africa , Potatoes -- Therapeutic use , Medicinal plants
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10322 , http://hdl.handle.net/10948/1228 , Potatoes -- Africa , Potatoes -- Therapeutic use , Medicinal plants
- Description: The African potato is used as an African traditional medicine for its nutritional and medicinal properties. Most research has been carried out on H. hemerocallidea, with very little or nothing on other Hypoxis spp. The main aim of this project was to provide scientific data on the anticancer, anti-inflammatory and antioxidant properties of H. hemerocallidea, H. stellipilis and H. sobolifera chloroform extracts and their active compounds. The hypoxoside and phytosterol contents of the three Hypoxis spp. were determined using TLC, HPLC and GC. H. hemerocallidea and H. sobolifera chloroform extracts contained the highest amounts of hypoxoside and β-sitosterol, respectively. For the anticancer properties, cytotoxicity of the Hypoxis extracts and its purified compounds were determined against the HeLa, HT-29 and MCF-7 cancer cell lines (using MTT), and PBMCs (using CellTiter-Blue®). H. sobolifera had the best cytotoxicity against the three cancer cell lines, whereas H. stellipilis stimulated HeLa and HT-29 cancer cell growth. IC50 values of hypoxoside and rooperol were determined. DNA cell cycle arrest (using PI staining) occurred in the late G1/early S (confirmed by increased p21Waf1/Cip1 expression) and G2/M phases after 15 and 48 hrs, respectively, when treated with Hypoxis extracts and rooperol. H. sobolifera and rooperol activated caspase-3 and -7 (using fluorescently labelled antibodies) in HeLa and HT-29 cancer cells, and caspase-7 in MCF-7 cancer cells after 48 hrs. Annexin V binding to phosphatidylserines in rooperol treated U937 cells confirmed early apoptosis after 15 hrs. The TUNEL assay showed DNA fragmentation in the three cancer cell lines when treated with H. sobolifera and rooperol for 48 hrs. A shift pass the G2/M phase has led to the investigation of endoreduplication, which was confirmed by cell/nucleus size, and anti-apoptotic proteins (Akt, phospho-Akt, phospho-Bcl-2 and p21Waf1/Cip1). U937 cell differentiation to monocyte-macrophages was optimized using PMA and 1,25(OH)2D3, which was confirmed by morphological and biochemical changes. For the anti-inflammatory properties, Hypoxis extracts and rooperol significantly increased NO production in monocyte-macrophages (pre-loaded with DAF-2 DA) and phagocytosis of pHrodoTM E. coli BioParticles®. The treatments had no effect on COX-2 expression in monocyte-macrophages. The phytosterols significantly increased IL-1β and IL-6 secretion xv (using the FlowCytomix Multiplex human Th1/Th2 10plex Kit I) in the PBMCs of one donor. For the antioxidant properties, Hypoxis extracts and rooperol significantly increased ROS production in undifferentiated and differentiated U937 cells, which were pre-loaded with DCFH-DA. Hypoxis extracts and purified compounds had ferric reducing activities, but only rooperol had ferric reducing activities significantly greater than ascorbic acid. β-sitosterol, campesterol and cholesterol significantly increased SOD activity in Chang liver cells, while H. stellipilis, H. sobolifera and rooperol decreased SOD activity. Anticancer, anti-inflammatory and antioxidant properties of the Hypoxis extracts may be attributed to the β-sitosterol content, because Hypoxis chloroform extracts contained very little or no hypoxoside. Unidentified compounds, and synergistic and additive effects of the compounds may have contributed to the biological effects. This study confirms previous reports that rooperol is the active compound. Results provide scientific data on the medicinal properties of one of the most frequently used medicinal plants in South Africa.
- Full Text:
- Date Issued: 2010
- Authors: Boukes, Gerhardt Johannes
- Date: 2010
- Subjects: Potatoes -- Africa , Potatoes -- Therapeutic use , Medicinal plants
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10322 , http://hdl.handle.net/10948/1228 , Potatoes -- Africa , Potatoes -- Therapeutic use , Medicinal plants
- Description: The African potato is used as an African traditional medicine for its nutritional and medicinal properties. Most research has been carried out on H. hemerocallidea, with very little or nothing on other Hypoxis spp. The main aim of this project was to provide scientific data on the anticancer, anti-inflammatory and antioxidant properties of H. hemerocallidea, H. stellipilis and H. sobolifera chloroform extracts and their active compounds. The hypoxoside and phytosterol contents of the three Hypoxis spp. were determined using TLC, HPLC and GC. H. hemerocallidea and H. sobolifera chloroform extracts contained the highest amounts of hypoxoside and β-sitosterol, respectively. For the anticancer properties, cytotoxicity of the Hypoxis extracts and its purified compounds were determined against the HeLa, HT-29 and MCF-7 cancer cell lines (using MTT), and PBMCs (using CellTiter-Blue®). H. sobolifera had the best cytotoxicity against the three cancer cell lines, whereas H. stellipilis stimulated HeLa and HT-29 cancer cell growth. IC50 values of hypoxoside and rooperol were determined. DNA cell cycle arrest (using PI staining) occurred in the late G1/early S (confirmed by increased p21Waf1/Cip1 expression) and G2/M phases after 15 and 48 hrs, respectively, when treated with Hypoxis extracts and rooperol. H. sobolifera and rooperol activated caspase-3 and -7 (using fluorescently labelled antibodies) in HeLa and HT-29 cancer cells, and caspase-7 in MCF-7 cancer cells after 48 hrs. Annexin V binding to phosphatidylserines in rooperol treated U937 cells confirmed early apoptosis after 15 hrs. The TUNEL assay showed DNA fragmentation in the three cancer cell lines when treated with H. sobolifera and rooperol for 48 hrs. A shift pass the G2/M phase has led to the investigation of endoreduplication, which was confirmed by cell/nucleus size, and anti-apoptotic proteins (Akt, phospho-Akt, phospho-Bcl-2 and p21Waf1/Cip1). U937 cell differentiation to monocyte-macrophages was optimized using PMA and 1,25(OH)2D3, which was confirmed by morphological and biochemical changes. For the anti-inflammatory properties, Hypoxis extracts and rooperol significantly increased NO production in monocyte-macrophages (pre-loaded with DAF-2 DA) and phagocytosis of pHrodoTM E. coli BioParticles®. The treatments had no effect on COX-2 expression in monocyte-macrophages. The phytosterols significantly increased IL-1β and IL-6 secretion xv (using the FlowCytomix Multiplex human Th1/Th2 10plex Kit I) in the PBMCs of one donor. For the antioxidant properties, Hypoxis extracts and rooperol significantly increased ROS production in undifferentiated and differentiated U937 cells, which were pre-loaded with DCFH-DA. Hypoxis extracts and purified compounds had ferric reducing activities, but only rooperol had ferric reducing activities significantly greater than ascorbic acid. β-sitosterol, campesterol and cholesterol significantly increased SOD activity in Chang liver cells, while H. stellipilis, H. sobolifera and rooperol decreased SOD activity. Anticancer, anti-inflammatory and antioxidant properties of the Hypoxis extracts may be attributed to the β-sitosterol content, because Hypoxis chloroform extracts contained very little or no hypoxoside. Unidentified compounds, and synergistic and additive effects of the compounds may have contributed to the biological effects. This study confirms previous reports that rooperol is the active compound. Results provide scientific data on the medicinal properties of one of the most frequently used medicinal plants in South Africa.
- Full Text:
- Date Issued: 2010
Cultural villages inherited tradition and "African culture": a case study of Mgwali Cultural Village in the Eastern Cape
- Authors: Bovana, Solomzi Victor
- Date: 2010
- Subjects: Tourism -- South Africa -- Eastern Cape , Heritage tourism -- South Africa -- Eastern Cape , Culture and tourism -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA (History)
- Identifier: vital:11537 , http://hdl.handle.net/10353/552 , Tourism -- South Africa -- Eastern Cape , Heritage tourism -- South Africa -- Eastern Cape , Culture and tourism -- South Africa -- Eastern Cape
- Description: A growing number of studies concerning cultural villages have in most instances tended to focus on the cultural village as almost legitimately self-explanatory and have not been particularly concerned with either how a particular history is produced in and through these villages, or with the ways that particular discourses and practices associated with heritage, tourism, community and development intersect in the production of these meanings. As such Mgwali Cultural Village seemed to promise something different in the form of cultural villages. The thesis argues that Mgwali Cultural Village is unique in the history of cultural villages in that it moves away from presenting a cultural village in Africa as tribal and primitive. It does this by opening up spaces for other aspects such as Christianity and resistance politics, story of Tiyo Soga rather than focusing and confining itself only to aspects cultural portraying Africans and traditional. It is imperative that cultural villages ought to be understood within a broader framework and context where its definition and presentation is not trapped into an anthropological paradigm thinking of exploring and discovering something new by tourists which they are not familiar with. However, the thesis also argues that much as Mgwali Cultural Village promised something new from the known through depiction of other aspects, those histories seem to be absent or marginal at the Cultural Village. The only aspects that are fore grounded are traditions and culture thus freezing Mgwali as a village and its people in time as if they have not evolved and its cultures are static and not dynamic. The thesis therefore explores all those contradictions, silences, or absence thereof of other stories and histories.
- Full Text:
- Date Issued: 2010
- Authors: Bovana, Solomzi Victor
- Date: 2010
- Subjects: Tourism -- South Africa -- Eastern Cape , Heritage tourism -- South Africa -- Eastern Cape , Culture and tourism -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA (History)
- Identifier: vital:11537 , http://hdl.handle.net/10353/552 , Tourism -- South Africa -- Eastern Cape , Heritage tourism -- South Africa -- Eastern Cape , Culture and tourism -- South Africa -- Eastern Cape
- Description: A growing number of studies concerning cultural villages have in most instances tended to focus on the cultural village as almost legitimately self-explanatory and have not been particularly concerned with either how a particular history is produced in and through these villages, or with the ways that particular discourses and practices associated with heritage, tourism, community and development intersect in the production of these meanings. As such Mgwali Cultural Village seemed to promise something different in the form of cultural villages. The thesis argues that Mgwali Cultural Village is unique in the history of cultural villages in that it moves away from presenting a cultural village in Africa as tribal and primitive. It does this by opening up spaces for other aspects such as Christianity and resistance politics, story of Tiyo Soga rather than focusing and confining itself only to aspects cultural portraying Africans and traditional. It is imperative that cultural villages ought to be understood within a broader framework and context where its definition and presentation is not trapped into an anthropological paradigm thinking of exploring and discovering something new by tourists which they are not familiar with. However, the thesis also argues that much as Mgwali Cultural Village promised something new from the known through depiction of other aspects, those histories seem to be absent or marginal at the Cultural Village. The only aspects that are fore grounded are traditions and culture thus freezing Mgwali as a village and its people in time as if they have not evolved and its cultures are static and not dynamic. The thesis therefore explores all those contradictions, silences, or absence thereof of other stories and histories.
- Full Text:
- Date Issued: 2010
An investigation of IgE regulation by recombinant soluble IgE receptors and co-receptors in human cell culture models
- Authors: Bowles, Sandra Lyn
- Date: 2010
- Subjects: Immunoglobulin E , Allergy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10321 , http://hdl.handle.net/10948/1231 , Immunoglobulin E , Allergy
- Description: Type I hypersensitivities are mediated by the IgE antibody. The effector functions and synthesis of IgE result from interactions with a network of proteins that include a high affinity (FcRIα) and a low affinity (CD23, FcRII) Fc receptor in conjunction with the B lymphocyte receptor, CD21. CD23 is a multifunctional type II transmembrane protein that binds its known ligands through its ectodomain either as a membrane-bound or soluble receptor generated in vivo by specific proteolytic cleavages. IgE production is primarily regulated by interactions between IgE, CD23 and CD21. Despite its importance for development of strategies to limit hypersensitivity, precise information about the molecular interactions remains limited. During this study, I engineered, expressed and purified from bacteria three soluble human CD23 fragments that are normally formed in vivo and shed from the cell surface (1) derCD23, amino acids 156-298 (2) sCD23, amino acids 150-321 and (3) the entire ectodomain, exCD23, amino acids 48-321 to examine the comparative binding of recombinant human CD21 SCR 1-2 and native human IgE to these fragments. Gel filtration HPLC revealed that derCD23 and sCD23 were monomeric whereas exCD23 assembled as a heterogeneous mixture that included trimers and monomers. At the concentrations utilized, CD23 fragments sCD23 and exCD23 bound CD21 with similar affinity, whereas interaction between derCD23 and CD21 was minimal when analyzed by surface plasmon resonance (SPR) spectroscopy. These findings suggest that penultimate “tail” amino acids between 298 and 321 stabilize CD21 attachment, although it cannot be ruled out, the region between Met 150 and Ser 156 may also play a role in binding CD21 SCR 1-2. In contrast, there is a progressive increment in the affinity of soluble fragments (exCD23>sCD23>derCD23) for IgE, upon increasing length of the proximal CD23 “stalk” domain. These findings highlight the differences in both the structural basis and affinity of the three physiological fragments of human CD23 for the ligands CD21 and IgE and underscore the complexity of CD23-mediated regulatory networks. It was found that B-cells only make up ~5% of the PBMC population, and that these cells were able to be activated, via STAT-6 phosphorylation, to enter class switch recombination (CSR) by the addition of switch factors (IL-4 and anti-CD40). Titration experiments dictated that 25 ng/mL of CD23 was the most efficient concentration to up-regulate IgE synthesis in PBMCs; furthermore, soluble CD23 proteins were incubated with PBMCs in the presence and absence of CD21 SCR 1-2 to investigate the effect that these recombinant proteins have on IgE synthesis. Results showed that the influence of recombinant proteins (both CD23 and CD21) on IgE synthesis was slight. It was shown that while derCD23 had no significant effect, monomeric sCD23 down-regulated, and the mixture of monomeric and oligomeric exCD23 up-regulated IgE synthesis. On addition of CD21 SCR 1-2 to the cells switched and treated with soluble CD23, it was found that in both cases for sCD23 and exCD23, IgE synthesis was increased, while for derCD23, there was no noticeable difference in IgE synthesis. This confirmed previous data showing the lack of binding between derCD23 and CD21 SCR 1-2. The exact binding site for CD21 on the CD23 molecule is unknown, and incompletely represented in the NMR and crystal structures. It is thought that CD21 binds to the C-terminal tail section, not present in derCD23. It is therefore likely that only a negative-feedback mechanism operates with derCD23 to regulate IgE synthesis. Further investigation of the binding of CD23 fragments to SCR 5-8 of CD21 and the effect of this on IgE synthesis may lead to a potential therapeutic role for derCD23 in the treatment of allergic disease. Data accumulated in this study suggests that investigating the modulation of oligomeric state and thus the activity of soluble CD23 fragments may be important in the construction of new regulators of IgE synthesis.
- Full Text:
- Date Issued: 2010
- Authors: Bowles, Sandra Lyn
- Date: 2010
- Subjects: Immunoglobulin E , Allergy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10321 , http://hdl.handle.net/10948/1231 , Immunoglobulin E , Allergy
- Description: Type I hypersensitivities are mediated by the IgE antibody. The effector functions and synthesis of IgE result from interactions with a network of proteins that include a high affinity (FcRIα) and a low affinity (CD23, FcRII) Fc receptor in conjunction with the B lymphocyte receptor, CD21. CD23 is a multifunctional type II transmembrane protein that binds its known ligands through its ectodomain either as a membrane-bound or soluble receptor generated in vivo by specific proteolytic cleavages. IgE production is primarily regulated by interactions between IgE, CD23 and CD21. Despite its importance for development of strategies to limit hypersensitivity, precise information about the molecular interactions remains limited. During this study, I engineered, expressed and purified from bacteria three soluble human CD23 fragments that are normally formed in vivo and shed from the cell surface (1) derCD23, amino acids 156-298 (2) sCD23, amino acids 150-321 and (3) the entire ectodomain, exCD23, amino acids 48-321 to examine the comparative binding of recombinant human CD21 SCR 1-2 and native human IgE to these fragments. Gel filtration HPLC revealed that derCD23 and sCD23 were monomeric whereas exCD23 assembled as a heterogeneous mixture that included trimers and monomers. At the concentrations utilized, CD23 fragments sCD23 and exCD23 bound CD21 with similar affinity, whereas interaction between derCD23 and CD21 was minimal when analyzed by surface plasmon resonance (SPR) spectroscopy. These findings suggest that penultimate “tail” amino acids between 298 and 321 stabilize CD21 attachment, although it cannot be ruled out, the region between Met 150 and Ser 156 may also play a role in binding CD21 SCR 1-2. In contrast, there is a progressive increment in the affinity of soluble fragments (exCD23>sCD23>derCD23) for IgE, upon increasing length of the proximal CD23 “stalk” domain. These findings highlight the differences in both the structural basis and affinity of the three physiological fragments of human CD23 for the ligands CD21 and IgE and underscore the complexity of CD23-mediated regulatory networks. It was found that B-cells only make up ~5% of the PBMC population, and that these cells were able to be activated, via STAT-6 phosphorylation, to enter class switch recombination (CSR) by the addition of switch factors (IL-4 and anti-CD40). Titration experiments dictated that 25 ng/mL of CD23 was the most efficient concentration to up-regulate IgE synthesis in PBMCs; furthermore, soluble CD23 proteins were incubated with PBMCs in the presence and absence of CD21 SCR 1-2 to investigate the effect that these recombinant proteins have on IgE synthesis. Results showed that the influence of recombinant proteins (both CD23 and CD21) on IgE synthesis was slight. It was shown that while derCD23 had no significant effect, monomeric sCD23 down-regulated, and the mixture of monomeric and oligomeric exCD23 up-regulated IgE synthesis. On addition of CD21 SCR 1-2 to the cells switched and treated with soluble CD23, it was found that in both cases for sCD23 and exCD23, IgE synthesis was increased, while for derCD23, there was no noticeable difference in IgE synthesis. This confirmed previous data showing the lack of binding between derCD23 and CD21 SCR 1-2. The exact binding site for CD21 on the CD23 molecule is unknown, and incompletely represented in the NMR and crystal structures. It is thought that CD21 binds to the C-terminal tail section, not present in derCD23. It is therefore likely that only a negative-feedback mechanism operates with derCD23 to regulate IgE synthesis. Further investigation of the binding of CD23 fragments to SCR 5-8 of CD21 and the effect of this on IgE synthesis may lead to a potential therapeutic role for derCD23 in the treatment of allergic disease. Data accumulated in this study suggests that investigating the modulation of oligomeric state and thus the activity of soluble CD23 fragments may be important in the construction of new regulators of IgE synthesis.
- Full Text:
- Date Issued: 2010
Mechanisms of habitat segregation between an invasive (Mytilus galloprovincialis) and an indigenous (Perna perna) mussel: adult growth and mortality
- Bownes, Sarah J, McQuaid, Christopher D
- Authors: Bownes, Sarah J , McQuaid, Christopher D
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6868 , http://hdl.handle.net/10962/d1011500
- Description: The invasive mussel Mytilus galloprovincialis and the indigenous mussel Perna perna coexist intertidally on the south coast of South Africa through partial vertical habitat segregation: M. galloprovincialis dominates the upper shore and P. perna the lower shore. Recruitment patterns can explain the zonation of P. perna, but not the invasive species. We examined the role of post-recruitment interactions by measuring spatial and temporal differences in adult growth and mortality rates of the two species. Specifically, we tested the hypothesis that interspecific differences in growth and mortality reflect adult distribution patterns. The two study locations, Plettenberg Bay and Tsitsikamma, are 70 km apart with two sites (separated by 300–400 m) per location, each divided into three vertical zones. Growth was measured seasonally using different marking methods in 2001 and 2003. Cumulative adult mortality was measured through summer in 2003/2004. Both species generally grew more slowly upshore, but they showed different effects of season. For P. perna, growth was significantly reduced in winter in the low zone, but unaffected by season in the high zone. For M. galloprovincialis, growth was either unaffected by season or increased in winter, even in the high zone. Thus, growth of P. perna and M. galloprovincialis was reduced under cool winter and warm summer temperatures, respectively; and while growth was more similar between species in summer, M. galloprovincialis grew much faster than P. perna in winter. Mortality of P. perna increased upshore. For M. galloprovincialis, mortality was not zone-dependent and was significantly greater than for P. perna on the low-shore and (generally) across the shore in Tsitsikamma. Both species had higher growth and mortality rates in Plettenberg Bay than in Tsitsikamma. Thus, P. perna seems able to maintain spatial dominance on the low-shore and at certain sites because of higher mortality of M. galloprovincialis. We conclude that seasonality in growth of the two species reflects their biogeographic affinities and that coexistence is possible through pre-recruitment effects that limit the vertical distribution of P. perna and post-recruitment effects that limit M. galloprovincialis.
- Full Text:
- Date Issued: 2010
- Authors: Bownes, Sarah J , McQuaid, Christopher D
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6868 , http://hdl.handle.net/10962/d1011500
- Description: The invasive mussel Mytilus galloprovincialis and the indigenous mussel Perna perna coexist intertidally on the south coast of South Africa through partial vertical habitat segregation: M. galloprovincialis dominates the upper shore and P. perna the lower shore. Recruitment patterns can explain the zonation of P. perna, but not the invasive species. We examined the role of post-recruitment interactions by measuring spatial and temporal differences in adult growth and mortality rates of the two species. Specifically, we tested the hypothesis that interspecific differences in growth and mortality reflect adult distribution patterns. The two study locations, Plettenberg Bay and Tsitsikamma, are 70 km apart with two sites (separated by 300–400 m) per location, each divided into three vertical zones. Growth was measured seasonally using different marking methods in 2001 and 2003. Cumulative adult mortality was measured through summer in 2003/2004. Both species generally grew more slowly upshore, but they showed different effects of season. For P. perna, growth was significantly reduced in winter in the low zone, but unaffected by season in the high zone. For M. galloprovincialis, growth was either unaffected by season or increased in winter, even in the high zone. Thus, growth of P. perna and M. galloprovincialis was reduced under cool winter and warm summer temperatures, respectively; and while growth was more similar between species in summer, M. galloprovincialis grew much faster than P. perna in winter. Mortality of P. perna increased upshore. For M. galloprovincialis, mortality was not zone-dependent and was significantly greater than for P. perna on the low-shore and (generally) across the shore in Tsitsikamma. Both species had higher growth and mortality rates in Plettenberg Bay than in Tsitsikamma. Thus, P. perna seems able to maintain spatial dominance on the low-shore and at certain sites because of higher mortality of M. galloprovincialis. We conclude that seasonality in growth of the two species reflects their biogeographic affinities and that coexistence is possible through pre-recruitment effects that limit the vertical distribution of P. perna and post-recruitment effects that limit M. galloprovincialis.
- Full Text:
- Date Issued: 2010
Integer optimisation for the selection of a fantasy league cricket team
- Authors: Brettenny, Warren James
- Date: 2010
- Subjects: Sports -- Research -- Methodology , Teamwork (Sports) , Cricket players
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10565 , http://hdl.handle.net/10948/1230 , Sports -- Research -- Methodology , Teamwork (Sports) , Cricket players
- Description: Sports fans often scrutinise the team selection strategies employed by their favourite team's coach or selection panel. Many of these fans believe that they can perform the selection process far better than those tasked with the responsibility. Fantasy leagues, provide a platform for fans to test their hand at this selection procedure. Twenty20 cricket is a new and exciting form of cricket and has become very popular in recent years. This research focuses on bringing these concepts together by proposing a binary integer program to determine a team selection strategy for fantasy league cricket. This is done in a Twenty20 setting. The approach used in this study focuses on evaluating the effectiveness of previously developed performance measures in a fantasy league setting. Adjustments to these measures are made and new measures are proposed. These measures are then used to select a fantasy league team using a prospective approach. This is done to provide fantasy league participants with a mathematical procedure for fantasy league team selection.
- Full Text:
- Date Issued: 2010
- Authors: Brettenny, Warren James
- Date: 2010
- Subjects: Sports -- Research -- Methodology , Teamwork (Sports) , Cricket players
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10565 , http://hdl.handle.net/10948/1230 , Sports -- Research -- Methodology , Teamwork (Sports) , Cricket players
- Description: Sports fans often scrutinise the team selection strategies employed by their favourite team's coach or selection panel. Many of these fans believe that they can perform the selection process far better than those tasked with the responsibility. Fantasy leagues, provide a platform for fans to test their hand at this selection procedure. Twenty20 cricket is a new and exciting form of cricket and has become very popular in recent years. This research focuses on bringing these concepts together by proposing a binary integer program to determine a team selection strategy for fantasy league cricket. This is done in a Twenty20 setting. The approach used in this study focuses on evaluating the effectiveness of previously developed performance measures in a fantasy league setting. Adjustments to these measures are made and new measures are proposed. These measures are then used to select a fantasy league team using a prospective approach. This is done to provide fantasy league participants with a mathematical procedure for fantasy league team selection.
- Full Text:
- Date Issued: 2010
The child accused in the criminal justice system
- Authors: Brink, Ronelle Bonita
- Date: 2010
- Subjects: Children's rights -- South Africa , Children -- Legal status, laws, etc -- South Africa , Children's rights -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10178 , http://hdl.handle.net/10948/1229 , Children's rights -- South Africa , Children -- Legal status, laws, etc -- South Africa , Children's rights -- Law and legislation -- South Africa
- Description: The high level of crime in South Africa raises the question about the failures of the criminal justice system on the one hand, and South Africa’s social policies on the other. Young people in South Africa can disproportionately be both victims and perpetrators of crime in the Republic of South Africa. The child accused in conflict with the law is dealt with in much the same way as their adult counterparts, as the criminal justice system was designed by adults for adults. South Africa became a signatory to the United Nations Convention on the Rights of the Child 19891(hereinafter referred to as UNCRC) on 16 June 1995. The UNCRC provides a backdrop to section 28 of the Constitution of the Republic of South Africa Act.2 Article 3(1) of the UNCRC provides as follows: “in all actions concerning children, whether undertaken by public or private social welfare institutions, courts of law, administrative authorities or legislative bodies, the best interests of the child shall be primary consideration.” South Africa is therefore according to article 40(3) of the UNCRC obliged to “establish laws, procedures, authorities and institutions specifically applicable to children in conflict with the law”.3 In terms of article 40(1) of the UNCRC “State Parties recognise the right of every child alleged as, accused of, or recognised as having infringed the penal law to be treated in a manner consistent with the promotion of the child’s sense of dignity and worth, which reinforces the child’s respect for the human rights and fundamental freedoms of others and which takes into account the child’s age and the desirability of promoting the child’s reintegration and the child’s assuming a constructive role in society.”4 1 Adopted by the General Assembly resolution 44/25 on 20 November 1989. 2 The Constitution of the Republic of South Africa Act, Act 108 of 1996. Hereinafter referred to as the “Constitution”. 3 South Law Reform Commission Discussion Paper 96. 4 United Nations Convention on the Rights of the Child adopted by the General Assembly resolution 44/25 on 20 November 1989. iv Synopsis 2003 states that “the Ratification of the UNCRC by the South African government in 1995 set the scene for broad-reaching policy and legislative change”.5 The Constitution includes a section protecting children’s rights, which includes the statement that children have the right not to be detained except as a measure of last resort and then for the shortest appropriate period of time, separate from adults and in conditions that take account of his/her age. 6 After being off Parliament’s agenda since 2003, the Child Justice Act7 has recently been reintroduced. The Act aims to ensure consistent, fair and appropriate treatment of the child accused in conflict with the law. The question arises whether the South African Criminal Justice system involving the child accused adequately recognises and protects the interests of the child accused, particularly in view of the present international legal position.
- Full Text:
- Date Issued: 2010
- Authors: Brink, Ronelle Bonita
- Date: 2010
- Subjects: Children's rights -- South Africa , Children -- Legal status, laws, etc -- South Africa , Children's rights -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10178 , http://hdl.handle.net/10948/1229 , Children's rights -- South Africa , Children -- Legal status, laws, etc -- South Africa , Children's rights -- Law and legislation -- South Africa
- Description: The high level of crime in South Africa raises the question about the failures of the criminal justice system on the one hand, and South Africa’s social policies on the other. Young people in South Africa can disproportionately be both victims and perpetrators of crime in the Republic of South Africa. The child accused in conflict with the law is dealt with in much the same way as their adult counterparts, as the criminal justice system was designed by adults for adults. South Africa became a signatory to the United Nations Convention on the Rights of the Child 19891(hereinafter referred to as UNCRC) on 16 June 1995. The UNCRC provides a backdrop to section 28 of the Constitution of the Republic of South Africa Act.2 Article 3(1) of the UNCRC provides as follows: “in all actions concerning children, whether undertaken by public or private social welfare institutions, courts of law, administrative authorities or legislative bodies, the best interests of the child shall be primary consideration.” South Africa is therefore according to article 40(3) of the UNCRC obliged to “establish laws, procedures, authorities and institutions specifically applicable to children in conflict with the law”.3 In terms of article 40(1) of the UNCRC “State Parties recognise the right of every child alleged as, accused of, or recognised as having infringed the penal law to be treated in a manner consistent with the promotion of the child’s sense of dignity and worth, which reinforces the child’s respect for the human rights and fundamental freedoms of others and which takes into account the child’s age and the desirability of promoting the child’s reintegration and the child’s assuming a constructive role in society.”4 1 Adopted by the General Assembly resolution 44/25 on 20 November 1989. 2 The Constitution of the Republic of South Africa Act, Act 108 of 1996. Hereinafter referred to as the “Constitution”. 3 South Law Reform Commission Discussion Paper 96. 4 United Nations Convention on the Rights of the Child adopted by the General Assembly resolution 44/25 on 20 November 1989. iv Synopsis 2003 states that “the Ratification of the UNCRC by the South African government in 1995 set the scene for broad-reaching policy and legislative change”.5 The Constitution includes a section protecting children’s rights, which includes the statement that children have the right not to be detained except as a measure of last resort and then for the shortest appropriate period of time, separate from adults and in conditions that take account of his/her age. 6 After being off Parliament’s agenda since 2003, the Child Justice Act7 has recently been reintroduced. The Act aims to ensure consistent, fair and appropriate treatment of the child accused in conflict with the law. The question arises whether the South African Criminal Justice system involving the child accused adequately recognises and protects the interests of the child accused, particularly in view of the present international legal position.
- Full Text:
- Date Issued: 2010
Fluorescence quenching and energy transfer in conjugates of quantum dots with zinc and indium tetraamino phthalocyanines
- Britton, Jonathan, Antunes, Edith M, Nyokong, Tebello
- Authors: Britton, Jonathan , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262638 , vital:53539 , xlink:href="https://doi.org/10.1016/j.jphotochem.2009.12.013"
- Description: CdTe QDs capped with mercapto propionic acid (MPA) and thioglycolic acid (TGA) were covalently linked to zinc and indium tetraaminophthalocyanines (TAPcs) using N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) as the coupling agents. The results presented give evidence in favour of formation of an amide bond between the MTAPc and CdTe QDs. Both the linked ZnTAPc–QD complexes and the mixture of QDs and ZnTAPc (without chemical linking) showed Förster resonance energy transfer (FRET), whereas the QD interactions with InTAPc yielded no evidence of FRET. Both MTAPcs quenched the QDs emission, with quenching constants of the order of 103–104 M−1. High energy transfer efficiencies were obtained in some cases (as high as 93%), due to the low donor to acceptor distances.
- Full Text:
- Date Issued: 2010
- Authors: Britton, Jonathan , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262638 , vital:53539 , xlink:href="https://doi.org/10.1016/j.jphotochem.2009.12.013"
- Description: CdTe QDs capped with mercapto propionic acid (MPA) and thioglycolic acid (TGA) were covalently linked to zinc and indium tetraaminophthalocyanines (TAPcs) using N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) as the coupling agents. The results presented give evidence in favour of formation of an amide bond between the MTAPc and CdTe QDs. Both the linked ZnTAPc–QD complexes and the mixture of QDs and ZnTAPc (without chemical linking) showed Förster resonance energy transfer (FRET), whereas the QD interactions with InTAPc yielded no evidence of FRET. Both MTAPcs quenched the QDs emission, with quenching constants of the order of 103–104 M−1. High energy transfer efficiencies were obtained in some cases (as high as 93%), due to the low donor to acceptor distances.
- Full Text:
- Date Issued: 2010
Photophysical studies of zinc and indium tetraaminophthalocyanines in the presence of CdTe quantum dots
- Authors: Britton, Jonathan
- Date: 2010
- Subjects: Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4332 , http://hdl.handle.net/10962/d1004993 , Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Description: CdTe QDs capped with mercaptopropionic acid (MPA) and thioglycolic acid (TGA) were covalently linked to zinc and indium tetraaminophthalocyanines (TAPcs) using N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) as the coupling agents. The results presented give evidence in favour of formation of an amide bond between the MTAPc and CdTe QDs. Both the linked ZnTAPc–QD complexes and the mixture of QDs and ZnTAPc (without chemical linking) showed Förster resonance energy transfer (FRET), though the linked showed less FRET, whereas the QD interactions with InTAPc yielded no evidence of FRET. Both MTAPcs quenched the QDs emission, with quenching constants of the order of 103–104M−1, binding constants of the order of 108-1010M-1 and the number of binding sites for the MTAPc upon the QD being 2. High energy transfer efficiencies were obtained (in some cases as high as 93%), due to the low donor to acceptor distances. Lastly, both MTAPc were shown to be poor optical limiters because their imaginary third-order susceptibility (Im[χ(3)]) was of the order of 10-17-10-16 (optimal range is 10-9-10-11), the hyperpolarizability (γ) of the order of 10-37-10-36 (optimal range is 10-29-10-34) and the k values were above one but below ten.
- Full Text:
- Date Issued: 2010
- Authors: Britton, Jonathan
- Date: 2010
- Subjects: Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4332 , http://hdl.handle.net/10962/d1004993 , Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Description: CdTe QDs capped with mercaptopropionic acid (MPA) and thioglycolic acid (TGA) were covalently linked to zinc and indium tetraaminophthalocyanines (TAPcs) using N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) as the coupling agents. The results presented give evidence in favour of formation of an amide bond between the MTAPc and CdTe QDs. Both the linked ZnTAPc–QD complexes and the mixture of QDs and ZnTAPc (without chemical linking) showed Förster resonance energy transfer (FRET), though the linked showed less FRET, whereas the QD interactions with InTAPc yielded no evidence of FRET. Both MTAPcs quenched the QDs emission, with quenching constants of the order of 103–104M−1, binding constants of the order of 108-1010M-1 and the number of binding sites for the MTAPc upon the QD being 2. High energy transfer efficiencies were obtained (in some cases as high as 93%), due to the low donor to acceptor distances. Lastly, both MTAPc were shown to be poor optical limiters because their imaginary third-order susceptibility (Im[χ(3)]) was of the order of 10-17-10-16 (optimal range is 10-9-10-11), the hyperpolarizability (γ) of the order of 10-37-10-36 (optimal range is 10-29-10-34) and the k values were above one but below ten.
- Full Text:
- Date Issued: 2010
An investigation into the competencies associated with change leadership : a case study analysis of an information technology organisation
- Authors: Britton, Leola
- Date: 2010
- Subjects: Organizational change -- Management
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:16138 , http://hdl.handle.net/10948/1227 , Organizational change -- Management
- Description: In this research, the researcher-consultant together with the management corps of a merged IT organisation, embarked on a process of participative research with the aim to identify the competencies and skills that are required of the management-leadership corps to drive a process of change management and to ensure the organisation will be characterised by sustained growth and development. In using participative research methodology, qualitative data was mainly gathered through informal interviews and focus group sessions to identify the competencies and skills that are defined as important for the change manager-cum-leader role within the merged IT organisation. In addition, a matrix was compiled to enable each manager/leader to undertake a self-assessment of how capable they are in using the identified competencies and skills. The outcome of the assessment provided an indication of the areas of competencies and skills that through various interventions would enable the management-leadership corps to deal with the challenges of change, as well as to guide those that report to them through a process of change. While the management-leadership corps – referred to as the Executive, Senior, and Middle Management cohorts – all require enhancing their change management / leadership competencies and skills capability, it is the Middle Management cohort that is better equipped to perform their change management and leadership role. During the research, focus group sessions enhanced a participative methodology to enable identification of competencies important to the IT Company’s vision, mission and core values, as well as opportunity to identify interventions that will encourage an on-going process of change, growth and development. However, there is indication that the members of the Executive and Senior Management cohorts assessed themselves higher on those competencies that relate directly to their functionary roles, rather than the change management-leadership role. The scope of a treatise limits an in-depth and expanded research endeavour; however, the methodology used provided information on how a platform for participation in a change management process can be enabled. Furthermore, this research gives indication of how a management-leadership strata can ‘buy-in’ to the process of change, growth and development, commencing with the self and, which is aimed to encourage the same in those that share responsibility for sustained growth and development of the IT company. The research is also example of how an applied sociology endeavour can be undertaken.
- Full Text:
- Date Issued: 2010
- Authors: Britton, Leola
- Date: 2010
- Subjects: Organizational change -- Management
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:16138 , http://hdl.handle.net/10948/1227 , Organizational change -- Management
- Description: In this research, the researcher-consultant together with the management corps of a merged IT organisation, embarked on a process of participative research with the aim to identify the competencies and skills that are required of the management-leadership corps to drive a process of change management and to ensure the organisation will be characterised by sustained growth and development. In using participative research methodology, qualitative data was mainly gathered through informal interviews and focus group sessions to identify the competencies and skills that are defined as important for the change manager-cum-leader role within the merged IT organisation. In addition, a matrix was compiled to enable each manager/leader to undertake a self-assessment of how capable they are in using the identified competencies and skills. The outcome of the assessment provided an indication of the areas of competencies and skills that through various interventions would enable the management-leadership corps to deal with the challenges of change, as well as to guide those that report to them through a process of change. While the management-leadership corps – referred to as the Executive, Senior, and Middle Management cohorts – all require enhancing their change management / leadership competencies and skills capability, it is the Middle Management cohort that is better equipped to perform their change management and leadership role. During the research, focus group sessions enhanced a participative methodology to enable identification of competencies important to the IT Company’s vision, mission and core values, as well as opportunity to identify interventions that will encourage an on-going process of change, growth and development. However, there is indication that the members of the Executive and Senior Management cohorts assessed themselves higher on those competencies that relate directly to their functionary roles, rather than the change management-leadership role. The scope of a treatise limits an in-depth and expanded research endeavour; however, the methodology used provided information on how a platform for participation in a change management process can be enabled. Furthermore, this research gives indication of how a management-leadership strata can ‘buy-in’ to the process of change, growth and development, commencing with the self and, which is aimed to encourage the same in those that share responsibility for sustained growth and development of the IT company. The research is also example of how an applied sociology endeavour can be undertaken.
- Full Text:
- Date Issued: 2010
Effect of repeated eccentric demands placed on the lower limb musculature during simulated Rugby Union play
- Authors: Brown, Lisa Gill
- Date: 2010
- Subjects: Sports injuries , Muscles -- Wounds and injuries , Tendons -- Wounds and injuries , Muscles -- Examination , Rugby football injuries , Rugby Union football players
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5114 , http://hdl.handle.net/10962/d1005192 , Sports injuries , Muscles -- Wounds and injuries , Tendons -- Wounds and injuries , Muscles -- Examination , Rugby football injuries , Rugby Union football players
- Description: Epidemiological studies consistently report that muscular strains are a primary injury type in rugby union with the majority of the strains occurring to the quadricep and hamstring musculature. Recently it has been suggested that poor eccentric muscular strength is a precursor to hamstring and quadriceps strains during intermittent sports that require rapid acceleration and deceleration. Despite the high incidence of these muscle injuries in Rugby Union there has been little research into the possible mechanisms involved. Thus, the purpose of this study was to measure the physiological and perceptual responses during a simulated Rugby Union laboratory protocol and further, to identify changes in muscle recruitment patterns and muscle strength over time by comparing this protocol to a continuous, constant load protocol covering the same distance. The experimental condition (EXP) required university level players to perform 80 minutes of simulated rugby union play in a laboratory setting (on a walkway of 22m) which was compared to that of a control condition (CON) which involved subjects covering the same distance, at a constant speed of 4.2km.h-1 on a treadmill. Physiological, biophysical and perceptual responses were measured pre-, at half-time and post-protocol. Heart rate was significantly (p<0.01) greater as a result of EXP in comparison to the CON. Electromyography (EMG) of the vastus medialis was significantly (p<0.01) greater during the CON protocol. The EXP condition elicited higher iEMG activity in the hamstring musculature at all time intervals. In addition the iEMG of the semitendinosus decreased significantly (p<0.01) as a result of the EXP protocol. Peak eccentric knee extensors (EXT) (-13.19%) and flexors (FLEX) (-12.81%) torque decreased significantly during the experimental protocol. After passive half-time (236.67 + 56.27Nm (EXT) and 173.89 + 33.3NM (FLEX)) and at the end of the protocol (220.39 + 55.16Nm and 162.89 + 30.66Nm) reduced relative to pre protocol (253.89 + 54.54Nm and 186.83 + 33.3Nm). Peak eccentric knee extensors did not change during the control protocol. „Central‟ and ‟Local” Rating of Perceived Exertion values were significantly (P<0.01) greater during the EXP protocol with an increased incidence of hamstring discomfort and perceived pain (5 out of 10). The EXP protocol resulted in significantly (p<0.01) increased incidence of delayed onset muscle soreness (DOMS). In conclusion, a stop-start laboratory protocol elicited increased heart rate, negatively impacted on muscle activity of the hamstrings, decreased eccentric strength in the lower limb musculature, resulted in increased ratings of „Central‟ and „Local‟ exertion and increased pain perception and increased incidence of DOMS. Thus, a stop-start rugby specific laboratory protocol has a negative impact on performance. Due to the specificity of the protocol being designed to match the demands of competitive match play it is expected that these changes in heart rate, muscle activity and strength, particularly eccentric strength, will impact negativity on performance during rugby match play and increase the likelihood of injury
- Full Text:
- Date Issued: 2010
- Authors: Brown, Lisa Gill
- Date: 2010
- Subjects: Sports injuries , Muscles -- Wounds and injuries , Tendons -- Wounds and injuries , Muscles -- Examination , Rugby football injuries , Rugby Union football players
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5114 , http://hdl.handle.net/10962/d1005192 , Sports injuries , Muscles -- Wounds and injuries , Tendons -- Wounds and injuries , Muscles -- Examination , Rugby football injuries , Rugby Union football players
- Description: Epidemiological studies consistently report that muscular strains are a primary injury type in rugby union with the majority of the strains occurring to the quadricep and hamstring musculature. Recently it has been suggested that poor eccentric muscular strength is a precursor to hamstring and quadriceps strains during intermittent sports that require rapid acceleration and deceleration. Despite the high incidence of these muscle injuries in Rugby Union there has been little research into the possible mechanisms involved. Thus, the purpose of this study was to measure the physiological and perceptual responses during a simulated Rugby Union laboratory protocol and further, to identify changes in muscle recruitment patterns and muscle strength over time by comparing this protocol to a continuous, constant load protocol covering the same distance. The experimental condition (EXP) required university level players to perform 80 minutes of simulated rugby union play in a laboratory setting (on a walkway of 22m) which was compared to that of a control condition (CON) which involved subjects covering the same distance, at a constant speed of 4.2km.h-1 on a treadmill. Physiological, biophysical and perceptual responses were measured pre-, at half-time and post-protocol. Heart rate was significantly (p<0.01) greater as a result of EXP in comparison to the CON. Electromyography (EMG) of the vastus medialis was significantly (p<0.01) greater during the CON protocol. The EXP condition elicited higher iEMG activity in the hamstring musculature at all time intervals. In addition the iEMG of the semitendinosus decreased significantly (p<0.01) as a result of the EXP protocol. Peak eccentric knee extensors (EXT) (-13.19%) and flexors (FLEX) (-12.81%) torque decreased significantly during the experimental protocol. After passive half-time (236.67 + 56.27Nm (EXT) and 173.89 + 33.3NM (FLEX)) and at the end of the protocol (220.39 + 55.16Nm and 162.89 + 30.66Nm) reduced relative to pre protocol (253.89 + 54.54Nm and 186.83 + 33.3Nm). Peak eccentric knee extensors did not change during the control protocol. „Central‟ and ‟Local” Rating of Perceived Exertion values were significantly (P<0.01) greater during the EXP protocol with an increased incidence of hamstring discomfort and perceived pain (5 out of 10). The EXP protocol resulted in significantly (p<0.01) increased incidence of delayed onset muscle soreness (DOMS). In conclusion, a stop-start laboratory protocol elicited increased heart rate, negatively impacted on muscle activity of the hamstrings, decreased eccentric strength in the lower limb musculature, resulted in increased ratings of „Central‟ and „Local‟ exertion and increased pain perception and increased incidence of DOMS. Thus, a stop-start rugby specific laboratory protocol has a negative impact on performance. Due to the specificity of the protocol being designed to match the demands of competitive match play it is expected that these changes in heart rate, muscle activity and strength, particularly eccentric strength, will impact negativity on performance during rugby match play and increase the likelihood of injury
- Full Text:
- Date Issued: 2010
The largest volcanic eruptions on Earth
- Bryan, Scott E, Peate, Ingrid Ukstins, Peate, David W, Self, Stephen, Jerram, Dougal A, Mawby, Michael R, Marsh, Julian S, Miller, Jodie A
- Authors: Bryan, Scott E , Peate, Ingrid Ukstins , Peate, David W , Self, Stephen , Jerram, Dougal A , Mawby, Michael R , Marsh, Julian S , Miller, Jodie A
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/132887 , vital:36902 , https://doi.org/10.1016/j.earscirev.2010.07.001
- Description: Large igneous provinces (LIPs) are sites of the most frequently recurring, largest volume basaltic and silicic eruptions in Earth history. These large-volume (> 1000 km3 dense rock equivalent) and large-magnitude (> M8) eruptions produce really extensive (104–105 km2) basaltic lava flow fields and silicic ignimbrites that are the main building blocks of LIPs.
- Full Text: false
- Date Issued: 2010
- Authors: Bryan, Scott E , Peate, Ingrid Ukstins , Peate, David W , Self, Stephen , Jerram, Dougal A , Mawby, Michael R , Marsh, Julian S , Miller, Jodie A
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/132887 , vital:36902 , https://doi.org/10.1016/j.earscirev.2010.07.001
- Description: Large igneous provinces (LIPs) are sites of the most frequently recurring, largest volume basaltic and silicic eruptions in Earth history. These large-volume (> 1000 km3 dense rock equivalent) and large-magnitude (> M8) eruptions produce really extensive (104–105 km2) basaltic lava flow fields and silicic ignimbrites that are the main building blocks of LIPs.
- Full Text: false
- Date Issued: 2010
Advanced monitoring system for bolted connections in vehicle construction
- Authors: Buchmann, Macro
- Date: 2010
- Subjects: Automobiles -- Design and construction , Motor vehicles -- Design and construction , Bolted joints
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9617 , http://hdl.handle.net/10948/1417 , Automobiles -- Design and construction , Motor vehicles -- Design and construction , Bolted joints
- Description: Bolted connections where used from the beginning of vehicle construction for joining two or more parts. The reliability of bolted connections is still a major problem. The objective of this research thesis is focused on an advanced monitoring system for bolted connections in vehicle construction. A mechanical “vibrating test bench”, which was developed by the aeronautical engineer Mr. Junkers, is being adapted, to suite the requirements of the automotive industry. It is designed according to DIN 65151 standards. The bolted connection is tightened to a specific torque to achieve the required preload forces and then exposed to an oscillating elastic shear force. The preload force and their loss are measured in relation to the number of load cycles. The ideal locking mechanism would be, if no settling occurs. Realistic in practice is the remaining of a sufficient preload force which doesn’t decry with time. The aim of this thesis is, to gain knowledge that will assist in the future control of the bolt locking procedure. The test bench can be used to verify the clamping capability of a bolted connection. With the dynamic computer-aided test system it will also be possible to test critical bolted joints and their safety, which reduces the probability of costly product recalls, or even severe cases of failure.
- Full Text:
- Date Issued: 2010
- Authors: Buchmann, Macro
- Date: 2010
- Subjects: Automobiles -- Design and construction , Motor vehicles -- Design and construction , Bolted joints
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9617 , http://hdl.handle.net/10948/1417 , Automobiles -- Design and construction , Motor vehicles -- Design and construction , Bolted joints
- Description: Bolted connections where used from the beginning of vehicle construction for joining two or more parts. The reliability of bolted connections is still a major problem. The objective of this research thesis is focused on an advanced monitoring system for bolted connections in vehicle construction. A mechanical “vibrating test bench”, which was developed by the aeronautical engineer Mr. Junkers, is being adapted, to suite the requirements of the automotive industry. It is designed according to DIN 65151 standards. The bolted connection is tightened to a specific torque to achieve the required preload forces and then exposed to an oscillating elastic shear force. The preload force and their loss are measured in relation to the number of load cycles. The ideal locking mechanism would be, if no settling occurs. Realistic in practice is the remaining of a sufficient preload force which doesn’t decry with time. The aim of this thesis is, to gain knowledge that will assist in the future control of the bolt locking procedure. The test bench can be used to verify the clamping capability of a bolted connection. With the dynamic computer-aided test system it will also be possible to test critical bolted joints and their safety, which reduces the probability of costly product recalls, or even severe cases of failure.
- Full Text:
- Date Issued: 2010
The E.coli RNA degradosome analysis of molecular chaperones and enolase
- Authors: Burger, Adélle
- Date: 2010
- Subjects: Molecular chaperones , Escherichia coli -- Biotechnology , Polyphosphates , Polyphosphates -- Biotechnology , RNA-protein interactions
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3950 , http://hdl.handle.net/10962/d1004009 , Molecular chaperones , Escherichia coli -- Biotechnology , Polyphosphates , Polyphosphates -- Biotechnology , RNA-protein interactions
- Description: Normal mRNA turnover is essential for genetic regulation within cells. The E. coli RNA degradosome, a large multi-component protein complex which originates through specific protein interactions, has been referred to as the “RNA decay machine” and is responsible for mRNA turnover. The degradosome functions to process RNA and its key components have been identified. The scaffold protein is RNase E and it tethers the degradosome to the cytoplasmic membrane. Polynucleotide phosphorylase (PNPase), ATP-dependent RNA helicase (RhlB helicase) and the glycolytic enzyme enolase associate with RNase E to form the degradosome. Polyphosphate kinase associates with the degradosome in substoichiometric amounts, as do the molecular chaperones DnaK and GroEL. The role of DnaK as well as that of enolase in the RNA degradosome is unknown. Very limited research has been conducted on the components of the RNA degradosome under conditions of stress. The aim of this study was to understand the role played by enolase in the assembly of the degradosome under conditions of stress, as well as investigating the protein levels of molecular chaperones under these conditions. The RNA degradosome was successfully purified through its scaffold protein using nickel-affinity chromatography. In vivo studies were performed to investigate the protein levels of DnaK and GroEL present in the degradosome under conditions of heat stress, and whether GroEL could functionally replace DnaK in the degradosome. To investigate the recruitment of enolase to the degradosome under heat stress, a subcellular fractionation was performed to determine the localization of enolase upon heat shock in vivo. The elevated temperature resulted in an increased concentration of enolase in the membrane fraction. To determine whether there is an interaction between enolase and DnaK, enolase activity assays were conducted in vitro. The effect of DnaK on enolase activity was measured upon quantifying DnaK and adding it to the enolase assays. For the first time it was observed that the activity of enolase increased with the addition of substoichiometric amounts of DnaK. This indicates that DnaK may be interacting with the RNA degradosome via enolase.
- Full Text:
- Date Issued: 2010
- Authors: Burger, Adélle
- Date: 2010
- Subjects: Molecular chaperones , Escherichia coli -- Biotechnology , Polyphosphates , Polyphosphates -- Biotechnology , RNA-protein interactions
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3950 , http://hdl.handle.net/10962/d1004009 , Molecular chaperones , Escherichia coli -- Biotechnology , Polyphosphates , Polyphosphates -- Biotechnology , RNA-protein interactions
- Description: Normal mRNA turnover is essential for genetic regulation within cells. The E. coli RNA degradosome, a large multi-component protein complex which originates through specific protein interactions, has been referred to as the “RNA decay machine” and is responsible for mRNA turnover. The degradosome functions to process RNA and its key components have been identified. The scaffold protein is RNase E and it tethers the degradosome to the cytoplasmic membrane. Polynucleotide phosphorylase (PNPase), ATP-dependent RNA helicase (RhlB helicase) and the glycolytic enzyme enolase associate with RNase E to form the degradosome. Polyphosphate kinase associates with the degradosome in substoichiometric amounts, as do the molecular chaperones DnaK and GroEL. The role of DnaK as well as that of enolase in the RNA degradosome is unknown. Very limited research has been conducted on the components of the RNA degradosome under conditions of stress. The aim of this study was to understand the role played by enolase in the assembly of the degradosome under conditions of stress, as well as investigating the protein levels of molecular chaperones under these conditions. The RNA degradosome was successfully purified through its scaffold protein using nickel-affinity chromatography. In vivo studies were performed to investigate the protein levels of DnaK and GroEL present in the degradosome under conditions of heat stress, and whether GroEL could functionally replace DnaK in the degradosome. To investigate the recruitment of enolase to the degradosome under heat stress, a subcellular fractionation was performed to determine the localization of enolase upon heat shock in vivo. The elevated temperature resulted in an increased concentration of enolase in the membrane fraction. To determine whether there is an interaction between enolase and DnaK, enolase activity assays were conducted in vitro. The effect of DnaK on enolase activity was measured upon quantifying DnaK and adding it to the enolase assays. For the first time it was observed that the activity of enolase increased with the addition of substoichiometric amounts of DnaK. This indicates that DnaK may be interacting with the RNA degradosome via enolase.
- Full Text:
- Date Issued: 2010