The chemistry of Algoa Bay ascidians
- Authors: Bromley, Candice Leigh
- Date: 2016
- Subjects: Sea squirts -- South Africa -- Algoa Bay , Marine metabolites , Chemistry, Analytic , Liquid chromatography , Inductively coupled plasma mass spectrometry , Metal ions , Nucleosides , Vanadium
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4560 , http://hdl.handle.net/10962/d1020606
- Description: This thesis investigates the chemistry of 25 ascidian species collected from Algoa Bay, South Africa with a concerted focus on metal accumulation by these ascidians and the possible interaction of these metals with ascidian metabolites. Chapter 2 details the screening techniques employed to establish the presence of nitrogenous metabolites (1H- 15N HMBC), hyper-accumulated metal ions (ICP-MS) and potential metal ion/ ascidian metabolite complexes (LC-ICP-MS/ESI-MS). Unfortunately, exhaustive attempts to detect intact metal ion/ascidian metabolite complexes through the use of liquid chromatography with parallel inductively coupled plasma mass spectrometry/electrospray mass spectrometry (LC-ICPMS/ ESI-MS) were unsuccessful. However, the LC-ICP-MS/ESI-MS data obtained for the crude organic extracts of six of the Algoa Bay ascidian species, Distaplia skoogi, Aplidium monile, Aplidium sp., Didemnum sp., Leptoclindines sp. and Polycitor sp. enabled identification of a number of ten halogenated metabolites, namely the indoles 2.28-2.30, and the tyramine and tyrosine derivatives (2.31-2.33, 2.41, 2.43, 2.44 and 2.46), within the ascidian extracts. This study confirmed that LC-ICP-MS/ESI-MS is a powerful tool for the dereplication of halogenated metabolites in complex mixtures especially where these compounds are present in very small amounts. This study is also the first report of these compounds (eight of which are known) in African ascidians. Compounds 2.32 and 2.46 have not been reported before from a marine source. Compounds 2.28-2.30 and 2.33 were present in sufficient amounts in the respective ascidian extracts to allow their isolation and structure elucidation using standard spectroscopic techniques Chapter 3 explores the ability of ascidians to accumulate a wide range of metal ions at concentrations which are often orders of magnitude higher than those of the surrounding sea water. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the total ion concentrations of 24 metals in 25 Algoa Bay ascidian species. To the best of our knowledge this is the largest and most extensive investigation of metal concentrations in a group of different ascidians occurring in the same area. Hypotheisizing that the metal ion concentrations for each ascidian specimen screened may represent a unique fingerprint for each specimen principal component analysis (PCA) was used in an attempt to establish whether there were spatial, temporal or phylogenetic relationships associated with the metal concentration fingerprints of the ascidians that formed part of this study. The PCA results showed that there were no statistically significant relationships between ascidian metal ion concentrations and either the collection year or the collection site of the ascidians. However, species from the family Didemnidae provided the clearest statistical evidence supporting a phylogenetic relationship between these ascidians and their hyperaccumulated metal ion profiles. Furthermore, these results suggested that ascidian species are indeed actively concentrating metal ions from the surrounding sea water and are not simply sinks for passively accumulated metal ions. Interestingly, the concentration of vanadium in the set of ascidians studied did not appear to correlate with any of the other metals accumulated by these ascidians suggesting that there is possibly a unique method employed for the accumulation of vanadium by ascidians. Chapter 4 investigated this possibility further after the nucleosides 4.10, 4.11, 4.13, 4.15, 4.17 and 4.40 were isolated from the vanadium accumulating ascidian Aplidium monile. Studies into the interactions between nucleosides and vanadyl are unfortunately rare and usually qualitative in nature with limited information provided about the stability or structures of the complexes formed. The vanadyl accumulating aplousobranch ascidians e.g. Aplidium monile dominated our study of Algoa Bay ascidians therefore providing us with the rationale to investigate the relatively little studied binding ability and stability of vandyl-nucleoside complexes. Potentiometric studies were conducted to determine the stability constants of complexes formed between the oxovanadium ion vanadyl (VO2+) and the commercially available nucleosides 4.10-4.14. The data afforded by this analysis clearly confirmed the complexity of the vanadyl/nucleoside complexation and suggested that guanosine (4.12) formed the most stable complex with oxovanadium ions. We were also able to establish a third protonation constant for the hydroxyl moiety in 4.12 with a logK 8.87 which has not been previously reported. Finally, Chapter 5 revisited the cytoxicity two Algoa Bay ascidians, Clavelina sp. and Atriolum marinense the extracts from which produced promising bioactivity results in previous studies against oesophageal cancer cells. The HP-20 fractionated extracts of Clavelina sp. and Atriolum marinense proved to be similalrly cytotoxic to breast cancer cells. With the exception for the 100% acetone(aq)fractions the NMR data for both species suggested that most active non polar fractions were dominated by what appeared to be structurally unremarkable fatty acid glycerides and as such were not pursued further. Purification of the 100% acetone(aq)fraction of A. marinense resulted in the isolation of a styrene trimer, 5.1, common to both ascidian extracts. The NMR simulation software WIN-DAISY was employed to confirm the structure of 5.1. Attempts to establish if 5.1 was an isolation artefact or a product of marine pollution were inconclusive
- Full Text:
- Date Issued: 2016
- Authors: Bromley, Candice Leigh
- Date: 2016
- Subjects: Sea squirts -- South Africa -- Algoa Bay , Marine metabolites , Chemistry, Analytic , Liquid chromatography , Inductively coupled plasma mass spectrometry , Metal ions , Nucleosides , Vanadium
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4560 , http://hdl.handle.net/10962/d1020606
- Description: This thesis investigates the chemistry of 25 ascidian species collected from Algoa Bay, South Africa with a concerted focus on metal accumulation by these ascidians and the possible interaction of these metals with ascidian metabolites. Chapter 2 details the screening techniques employed to establish the presence of nitrogenous metabolites (1H- 15N HMBC), hyper-accumulated metal ions (ICP-MS) and potential metal ion/ ascidian metabolite complexes (LC-ICP-MS/ESI-MS). Unfortunately, exhaustive attempts to detect intact metal ion/ascidian metabolite complexes through the use of liquid chromatography with parallel inductively coupled plasma mass spectrometry/electrospray mass spectrometry (LC-ICPMS/ ESI-MS) were unsuccessful. However, the LC-ICP-MS/ESI-MS data obtained for the crude organic extracts of six of the Algoa Bay ascidian species, Distaplia skoogi, Aplidium monile, Aplidium sp., Didemnum sp., Leptoclindines sp. and Polycitor sp. enabled identification of a number of ten halogenated metabolites, namely the indoles 2.28-2.30, and the tyramine and tyrosine derivatives (2.31-2.33, 2.41, 2.43, 2.44 and 2.46), within the ascidian extracts. This study confirmed that LC-ICP-MS/ESI-MS is a powerful tool for the dereplication of halogenated metabolites in complex mixtures especially where these compounds are present in very small amounts. This study is also the first report of these compounds (eight of which are known) in African ascidians. Compounds 2.32 and 2.46 have not been reported before from a marine source. Compounds 2.28-2.30 and 2.33 were present in sufficient amounts in the respective ascidian extracts to allow their isolation and structure elucidation using standard spectroscopic techniques Chapter 3 explores the ability of ascidians to accumulate a wide range of metal ions at concentrations which are often orders of magnitude higher than those of the surrounding sea water. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the total ion concentrations of 24 metals in 25 Algoa Bay ascidian species. To the best of our knowledge this is the largest and most extensive investigation of metal concentrations in a group of different ascidians occurring in the same area. Hypotheisizing that the metal ion concentrations for each ascidian specimen screened may represent a unique fingerprint for each specimen principal component analysis (PCA) was used in an attempt to establish whether there were spatial, temporal or phylogenetic relationships associated with the metal concentration fingerprints of the ascidians that formed part of this study. The PCA results showed that there were no statistically significant relationships between ascidian metal ion concentrations and either the collection year or the collection site of the ascidians. However, species from the family Didemnidae provided the clearest statistical evidence supporting a phylogenetic relationship between these ascidians and their hyperaccumulated metal ion profiles. Furthermore, these results suggested that ascidian species are indeed actively concentrating metal ions from the surrounding sea water and are not simply sinks for passively accumulated metal ions. Interestingly, the concentration of vanadium in the set of ascidians studied did not appear to correlate with any of the other metals accumulated by these ascidians suggesting that there is possibly a unique method employed for the accumulation of vanadium by ascidians. Chapter 4 investigated this possibility further after the nucleosides 4.10, 4.11, 4.13, 4.15, 4.17 and 4.40 were isolated from the vanadium accumulating ascidian Aplidium monile. Studies into the interactions between nucleosides and vanadyl are unfortunately rare and usually qualitative in nature with limited information provided about the stability or structures of the complexes formed. The vanadyl accumulating aplousobranch ascidians e.g. Aplidium monile dominated our study of Algoa Bay ascidians therefore providing us with the rationale to investigate the relatively little studied binding ability and stability of vandyl-nucleoside complexes. Potentiometric studies were conducted to determine the stability constants of complexes formed between the oxovanadium ion vanadyl (VO2+) and the commercially available nucleosides 4.10-4.14. The data afforded by this analysis clearly confirmed the complexity of the vanadyl/nucleoside complexation and suggested that guanosine (4.12) formed the most stable complex with oxovanadium ions. We were also able to establish a third protonation constant for the hydroxyl moiety in 4.12 with a logK 8.87 which has not been previously reported. Finally, Chapter 5 revisited the cytoxicity two Algoa Bay ascidians, Clavelina sp. and Atriolum marinense the extracts from which produced promising bioactivity results in previous studies against oesophageal cancer cells. The HP-20 fractionated extracts of Clavelina sp. and Atriolum marinense proved to be similalrly cytotoxic to breast cancer cells. With the exception for the 100% acetone(aq)fractions the NMR data for both species suggested that most active non polar fractions were dominated by what appeared to be structurally unremarkable fatty acid glycerides and as such were not pursued further. Purification of the 100% acetone(aq)fraction of A. marinense resulted in the isolation of a styrene trimer, 5.1, common to both ascidian extracts. The NMR simulation software WIN-DAISY was employed to confirm the structure of 5.1. Attempts to establish if 5.1 was an isolation artefact or a product of marine pollution were inconclusive
- Full Text:
- Date Issued: 2016
Towards an existential phenomenological interpretation of C.G. Jung's analytical psychology
- Authors: Brooke, Roger, 1953-
- Date: 1989
- Subjects: Jung, C G (Carl Gustav), 1875-1961 Existential phenomenology Phenomenology Psychoanalysis Psychology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3208 , http://hdl.handle.net/10962/d1011983
- Description: The central aim of this study was to interpret the psychology of C.G . Jung in the light of existential phenomenology, thereby to lay the foundations for an integrated phenomenological analytical psychology. It was recognised that although Jung introduced a poetic understanding of psychological life he tended to adhere theoretically to a Cartesian and natural scientific epistemology and ontology, in which the knower is separated from the known, and psychological life is encapsulated inside the human subject. Thus the main task, which defined generally the study's scope and limitations, was to undercut the lingering Cartesianism in Jung's thought, thereby to recover the world in which one lives as intrinsically and authentically psychological, and one's psychological life as irreducibly world-related. The ontological guidelines for this endeavour were taken primarily from Heidegger and Merleau-Ponty, but it was consistently argued that this hermeneutic movement towards an existential understanding is given within Jung's work itself. Thus: Jung's method is primarily hermeneutic-phenomenological; the psyche is not "mind" or an inner realm more or less linked to the body, but is the embodied life-world, and Jung's descriptions of it - of its autonomy, spatiality and bodiliness, for instance - achieve ontological clarity when it is articulated as Dasein; the self as the totality of the psyche is interpretated in terms of Dasein, and individuation involves differentiation, personalisation and appropriation within existence itself; the complexes, archetypally grounded, are the vital densities of incarnate life, ambiguously conscious and unconscious, known and lived; the archetypes are the fundamental necessities of psychological life, autonomous imaginal structures within which both body and world are founded. Imaginal autonomy is revealed ontically as the metaphorical reality of things, but since imaginal autonomy has no ground thought about psychological life is ultimately poetic. Where relevant, recent theoretical developments in analytical psychology were discussed, particularly the Developmental and Archetypal movements. A clinical study was presented to illustrate some of the main themes of the thesis. In conclusion, the main themes of an integrated phenomenological analytical psychology were outlined, and the central contributions of analytical psychology and existential phenomenology were highlighted.
- Full Text:
- Date Issued: 1989
- Authors: Brooke, Roger, 1953-
- Date: 1989
- Subjects: Jung, C G (Carl Gustav), 1875-1961 Existential phenomenology Phenomenology Psychoanalysis Psychology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3208 , http://hdl.handle.net/10962/d1011983
- Description: The central aim of this study was to interpret the psychology of C.G . Jung in the light of existential phenomenology, thereby to lay the foundations for an integrated phenomenological analytical psychology. It was recognised that although Jung introduced a poetic understanding of psychological life he tended to adhere theoretically to a Cartesian and natural scientific epistemology and ontology, in which the knower is separated from the known, and psychological life is encapsulated inside the human subject. Thus the main task, which defined generally the study's scope and limitations, was to undercut the lingering Cartesianism in Jung's thought, thereby to recover the world in which one lives as intrinsically and authentically psychological, and one's psychological life as irreducibly world-related. The ontological guidelines for this endeavour were taken primarily from Heidegger and Merleau-Ponty, but it was consistently argued that this hermeneutic movement towards an existential understanding is given within Jung's work itself. Thus: Jung's method is primarily hermeneutic-phenomenological; the psyche is not "mind" or an inner realm more or less linked to the body, but is the embodied life-world, and Jung's descriptions of it - of its autonomy, spatiality and bodiliness, for instance - achieve ontological clarity when it is articulated as Dasein; the self as the totality of the psyche is interpretated in terms of Dasein, and individuation involves differentiation, personalisation and appropriation within existence itself; the complexes, archetypally grounded, are the vital densities of incarnate life, ambiguously conscious and unconscious, known and lived; the archetypes are the fundamental necessities of psychological life, autonomous imaginal structures within which both body and world are founded. Imaginal autonomy is revealed ontically as the metaphorical reality of things, but since imaginal autonomy has no ground thought about psychological life is ultimately poetic. Where relevant, recent theoretical developments in analytical psychology were discussed, particularly the Developmental and Archetypal movements. A clinical study was presented to illustrate some of the main themes of the thesis. In conclusion, the main themes of an integrated phenomenological analytical psychology were outlined, and the central contributions of analytical psychology and existential phenomenology were highlighted.
- Full Text:
- Date Issued: 1989
Social criteria in the drama of Molìère
- Authors: Brooks, Beverley Anne
- Date: 1974
- Subjects: Molière, 1622-1673 -- Criticism and interpretation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3627 , http://hdl.handle.net/10962/d1009758
- Description: It is by no means an easy task to analyse and interpret the work of a dramatist such as Molière, for an interval of three hundred years inevitably blurs our perspective of the man and his intentions. We find ourselves unconsciously reading more into his lines than he possibly meant us to. We are tempted to attach significance to certain words and disregard others, in an arbitrary fashion. We try to reconstruct Molière's attitude towards his contemporaries and theirs to him, from evidence that is often flimsy and seldom reliable. Molière's very identity has been questioned to the extent that the authorship of his plays has been variously attributed to such different personalities as Louis XIV and the great Corneilleo. To these problems is added a further complication when one embarks upon a thesis dealing with the picture of society as it emerges from Molière's plays. Not only are we confronted with the difficulty of interpretation already mentioned, but also with the vastly different way in which pre-enlightenment man regarded social and political institutions. We of the twentieth century tend to take for granted the notions of liberty, fraternity, and equality. Had anyone formulated such ideas in the seventeenth century, it is doubtful whether they would have been accepted, since they contradict the very concept upon which society was based in the age of Louis XIV. This concept, broadly speaking, is that of a strict hierarchy in which everyone has his own appointed place. Obviously the notion of a hierarchy pre-supposes the inferiority of some and the superiority of others in the social structure of the day; and post-enlightenment thinking does not readily accept that some men should be privileged and others regarded as belonging naturally to the lower orders. Intro., p. 1-2.
- Full Text:
- Date Issued: 1974
- Authors: Brooks, Beverley Anne
- Date: 1974
- Subjects: Molière, 1622-1673 -- Criticism and interpretation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3627 , http://hdl.handle.net/10962/d1009758
- Description: It is by no means an easy task to analyse and interpret the work of a dramatist such as Molière, for an interval of three hundred years inevitably blurs our perspective of the man and his intentions. We find ourselves unconsciously reading more into his lines than he possibly meant us to. We are tempted to attach significance to certain words and disregard others, in an arbitrary fashion. We try to reconstruct Molière's attitude towards his contemporaries and theirs to him, from evidence that is often flimsy and seldom reliable. Molière's very identity has been questioned to the extent that the authorship of his plays has been variously attributed to such different personalities as Louis XIV and the great Corneilleo. To these problems is added a further complication when one embarks upon a thesis dealing with the picture of society as it emerges from Molière's plays. Not only are we confronted with the difficulty of interpretation already mentioned, but also with the vastly different way in which pre-enlightenment man regarded social and political institutions. We of the twentieth century tend to take for granted the notions of liberty, fraternity, and equality. Had anyone formulated such ideas in the seventeenth century, it is doubtful whether they would have been accepted, since they contradict the very concept upon which society was based in the age of Louis XIV. This concept, broadly speaking, is that of a strict hierarchy in which everyone has his own appointed place. Obviously the notion of a hierarchy pre-supposes the inferiority of some and the superiority of others in the social structure of the day; and post-enlightenment thinking does not readily accept that some men should be privileged and others regarded as belonging naturally to the lower orders. Intro., p. 1-2.
- Full Text:
- Date Issued: 1974
Biology, population dynamics and management of carpenter (Argyrozona argyrozona) an endemic South African reef fish
- Authors: Brouwer, Stephen Leonard
- Date: 2005
- Subjects: Reef fishes -- South Africa Sparidae -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5241 , http://hdl.handle.net/10962/d1005084
- Description: Carpenter, Argyrozona argyrozona (Valenciennes, 1830), is an endemic South African sparid fish. They form an important component of the commercial linefishery on the South African east coast, where they are the third most important species landed. Recent investigations revealed that the catch per unit effort (cpue) of this species has declined markedly since the early 1900’s. Despite these declines and the importance of this resource, remarkably little biological information on this species exists for providing management advice. This thesis investigates the life history of carpenter, particularly those aspects that are used for management. This includes an investigation into the stock distribution and identification of nursery areas, and an assessment of age, growth, reproduction and movement patterns. Age and growth was assessed using methods based on both otoliths and mark-recapture. Transverse sagittal sections from the Tsitsikamma National Park showed clear opaque and translucent growth increments. Marginal growth zone analysis and mark-recapture of chemically tagged fish (Oxytetracycline) revealed that these were deposited on an annual basis: opaque in summer and translucent in winter. A. argyrozona were found to be long lived (up to 27 years) and slow growing. Within reader (between counts) and between readers average percent error (APE) was 5.3 and 1.8, respectively, showing that readability of carpenter otoliths is high. Comparison between whole and sectioned otoliths showed that the former significantly under-estimated the age of fish older than 10 years (p<0.01). A large proportion (68%) of the individual growth rates derived from mark-recapture data were below those predicted by the otolith based von Bertalanffy growth model (p<0.01). This was attributed to the negative influence of external tags, as hydroids, frequently occurring on the tags of recaptured fish, were observed to cause severe lesions and in some cases, extensive fin damage. This brings into question the use of mark-recapture studies to calculate growth of some species. The effects of sampling design and sample size on age and growth estimation were assessed. The minimum sample size required to accurately estimate growth and mortality, and the effects of using either random or stratified sampling procedures were tested. Decimal and integer ageing both produced similar estimates of von Bertalanffy growth parameters, growth curves, spawner biomass-per-recruit (SB/R) and fishing mortality (F) estimates. Sampling monthly throughout the year and collecting data in a single large sample provided similar growth curves, von Bertalanffy, F and SB/R estimates. The data showed that estimates based on less than 300 random samples were unreliable. However, accurate growth parameter estimates were achievable with less than 200 samples if the sample was stratified with 10 or more samples per 2 cm size class. An investigation into the reproductive biology of A. argyrozona within the Tsitsikamma National Park revealed that they were serial spawning late gonochorists. The size at 50% maturity (L₅₀) was estimated at 292 and 297 mm FL for females and males, respectively. Both monthly gonadosomatic indices and macroscopically determined ovarian stages strongly suggest that A. argyrozona within the Tsitsikamma National Park spawn in the austral summer between November and April. The presence of post-ovulatory follicles (POF's) confirmed the six month spawning season, while monthly proportions of early (0-6 hour old) POF's showed that spawning frequency was highest (once every 1-2 days) from December to March. Although spawning season was more highly correlated to photoperiod (r = 0.859) than temperature (r = -0.161), the daily proportion of spawning fish was strongly correlated (r = 0.93) to ambient temperature over the range 9-22⁰C. Both spawning frequency and season increased with fish length. As a result of the allometric relationship between annual fecundity and fish mass a 3 kg fish was calculated to produce 5 fold more eggs per kilogram of body weight than a fish of 1 kg. In addition to producing more eggs per unit weight each year, larger fish also produce significantly larger eggs. Adult emigration and larval dispersal of A. argyrozona from the Tsitsikamma National Park (TNP), South Africa, were investigated using mark-recapture data and Acoustic Doppler Current Profiler measurements of currents. Tagging data showed that adult carpenter were mainly resident, with a small proportion (7%) leaving the TNP in both easterly and westerly directions. No relationship was found between fish movement patterns and fish size or time-at-liberty. Current patterns suggest that eggs and larvae spawned within the TNP are mainly transported eastwards towards established nursery grounds; the median estimated distance moved was 299 km (range 42-561 km) in 30 days (time to flexion). Given this pattern of ichthyoplankton dispersal together with the fact that adult carpenter within the TNP display a high degree of residency and that they are much more abundant than in adjacent fishing grounds (cpue = 23 times greater), it appears that the TNP protects a viable carpenter spawner population capable of seeding adjacent fishing grounds. Fishery independent biomass surveys and commercial linefish catch returns were used to elucidate the spatial patterns of A. argyrozona distributed along the South African continental shelf. Two distinct areas of abundance were determined, one on the central and the other on the eastern Agulhas Bank. Tagging studies revealed little exchange between them. Two distinct nursery areas were identified. These data suggest that in each area juvenile A. argyrozona settle and move inshore, and then move offshore as they grow. Otolith readability and growth rates varied between regions, with fish from the Eastern Cape having the lowest average percentage error and the slowest growth rates, readability decreased westward. L₅₀ varied between the central and eastern Agulhas Bank as did mass at length. Based on the distribution of carpenter, variability in otolith readability, mass at length, variation in growth and size at maturity, it is concluded that carpenter exist as two separate stocks, one on the central Agulhas Bank and the other on the eastern Agulhas Bank. SB/R, fecundity-per-recruit (Egg/R) and yield-per-recruit (Y/R) models were used to model both South African carpenter stocks. Owing to the allometric relationship between annual fecundity and individual size, Egg/R ratios were between 40 and 74% of SB/R at equivalent F. Egg/R ratios account for allometric increases in fecundity with size/age, and are therefore regarded as more accurate estimates of reproductive potential, and biological reference points for per-recruit analysis should wherever possible be based on this quantum. It is shown that the current length at first capture (lc) (250 mm TL) and F (at M = 0.1) will reduce Egg/R to 6.41% of the pristine value in the Eastern Cape and between 6.06 and 14.15% on the central Agulhas Bank, indicating that both stocks are heavily over exploited. An increase in lc from 250 to 350 mm TL and a 70% reduction in commercial fishing effort is recommended to attain a target reference point of 40% Egg/RF=0. Bag frequency analysis indicates that a reduction in daily bag limit from 10 to 4 fish.person¹.day⁻¹ would effect an equivalent reduction in recreational F. The trawl bycatch of carpenter is only 3% of the reported line catch, consequently restrictions to this fishery are not recommended.
- Full Text:
- Date Issued: 2005
- Authors: Brouwer, Stephen Leonard
- Date: 2005
- Subjects: Reef fishes -- South Africa Sparidae -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5241 , http://hdl.handle.net/10962/d1005084
- Description: Carpenter, Argyrozona argyrozona (Valenciennes, 1830), is an endemic South African sparid fish. They form an important component of the commercial linefishery on the South African east coast, where they are the third most important species landed. Recent investigations revealed that the catch per unit effort (cpue) of this species has declined markedly since the early 1900’s. Despite these declines and the importance of this resource, remarkably little biological information on this species exists for providing management advice. This thesis investigates the life history of carpenter, particularly those aspects that are used for management. This includes an investigation into the stock distribution and identification of nursery areas, and an assessment of age, growth, reproduction and movement patterns. Age and growth was assessed using methods based on both otoliths and mark-recapture. Transverse sagittal sections from the Tsitsikamma National Park showed clear opaque and translucent growth increments. Marginal growth zone analysis and mark-recapture of chemically tagged fish (Oxytetracycline) revealed that these were deposited on an annual basis: opaque in summer and translucent in winter. A. argyrozona were found to be long lived (up to 27 years) and slow growing. Within reader (between counts) and between readers average percent error (APE) was 5.3 and 1.8, respectively, showing that readability of carpenter otoliths is high. Comparison between whole and sectioned otoliths showed that the former significantly under-estimated the age of fish older than 10 years (p<0.01). A large proportion (68%) of the individual growth rates derived from mark-recapture data were below those predicted by the otolith based von Bertalanffy growth model (p<0.01). This was attributed to the negative influence of external tags, as hydroids, frequently occurring on the tags of recaptured fish, were observed to cause severe lesions and in some cases, extensive fin damage. This brings into question the use of mark-recapture studies to calculate growth of some species. The effects of sampling design and sample size on age and growth estimation were assessed. The minimum sample size required to accurately estimate growth and mortality, and the effects of using either random or stratified sampling procedures were tested. Decimal and integer ageing both produced similar estimates of von Bertalanffy growth parameters, growth curves, spawner biomass-per-recruit (SB/R) and fishing mortality (F) estimates. Sampling monthly throughout the year and collecting data in a single large sample provided similar growth curves, von Bertalanffy, F and SB/R estimates. The data showed that estimates based on less than 300 random samples were unreliable. However, accurate growth parameter estimates were achievable with less than 200 samples if the sample was stratified with 10 or more samples per 2 cm size class. An investigation into the reproductive biology of A. argyrozona within the Tsitsikamma National Park revealed that they were serial spawning late gonochorists. The size at 50% maturity (L₅₀) was estimated at 292 and 297 mm FL for females and males, respectively. Both monthly gonadosomatic indices and macroscopically determined ovarian stages strongly suggest that A. argyrozona within the Tsitsikamma National Park spawn in the austral summer between November and April. The presence of post-ovulatory follicles (POF's) confirmed the six month spawning season, while monthly proportions of early (0-6 hour old) POF's showed that spawning frequency was highest (once every 1-2 days) from December to March. Although spawning season was more highly correlated to photoperiod (r = 0.859) than temperature (r = -0.161), the daily proportion of spawning fish was strongly correlated (r = 0.93) to ambient temperature over the range 9-22⁰C. Both spawning frequency and season increased with fish length. As a result of the allometric relationship between annual fecundity and fish mass a 3 kg fish was calculated to produce 5 fold more eggs per kilogram of body weight than a fish of 1 kg. In addition to producing more eggs per unit weight each year, larger fish also produce significantly larger eggs. Adult emigration and larval dispersal of A. argyrozona from the Tsitsikamma National Park (TNP), South Africa, were investigated using mark-recapture data and Acoustic Doppler Current Profiler measurements of currents. Tagging data showed that adult carpenter were mainly resident, with a small proportion (7%) leaving the TNP in both easterly and westerly directions. No relationship was found between fish movement patterns and fish size or time-at-liberty. Current patterns suggest that eggs and larvae spawned within the TNP are mainly transported eastwards towards established nursery grounds; the median estimated distance moved was 299 km (range 42-561 km) in 30 days (time to flexion). Given this pattern of ichthyoplankton dispersal together with the fact that adult carpenter within the TNP display a high degree of residency and that they are much more abundant than in adjacent fishing grounds (cpue = 23 times greater), it appears that the TNP protects a viable carpenter spawner population capable of seeding adjacent fishing grounds. Fishery independent biomass surveys and commercial linefish catch returns were used to elucidate the spatial patterns of A. argyrozona distributed along the South African continental shelf. Two distinct areas of abundance were determined, one on the central and the other on the eastern Agulhas Bank. Tagging studies revealed little exchange between them. Two distinct nursery areas were identified. These data suggest that in each area juvenile A. argyrozona settle and move inshore, and then move offshore as they grow. Otolith readability and growth rates varied between regions, with fish from the Eastern Cape having the lowest average percentage error and the slowest growth rates, readability decreased westward. L₅₀ varied between the central and eastern Agulhas Bank as did mass at length. Based on the distribution of carpenter, variability in otolith readability, mass at length, variation in growth and size at maturity, it is concluded that carpenter exist as two separate stocks, one on the central Agulhas Bank and the other on the eastern Agulhas Bank. SB/R, fecundity-per-recruit (Egg/R) and yield-per-recruit (Y/R) models were used to model both South African carpenter stocks. Owing to the allometric relationship between annual fecundity and individual size, Egg/R ratios were between 40 and 74% of SB/R at equivalent F. Egg/R ratios account for allometric increases in fecundity with size/age, and are therefore regarded as more accurate estimates of reproductive potential, and biological reference points for per-recruit analysis should wherever possible be based on this quantum. It is shown that the current length at first capture (lc) (250 mm TL) and F (at M = 0.1) will reduce Egg/R to 6.41% of the pristine value in the Eastern Cape and between 6.06 and 14.15% on the central Agulhas Bank, indicating that both stocks are heavily over exploited. An increase in lc from 250 to 350 mm TL and a 70% reduction in commercial fishing effort is recommended to attain a target reference point of 40% Egg/RF=0. Bag frequency analysis indicates that a reduction in daily bag limit from 10 to 4 fish.person¹.day⁻¹ would effect an equivalent reduction in recreational F. The trawl bycatch of carpenter is only 3% of the reported line catch, consequently restrictions to this fishery are not recommended.
- Full Text:
- Date Issued: 2005
Investigating combinations of feature extraction and classification for improved image-based multimodal biometric systems at the feature level
- Authors: Brown, Dane
- Date: 2018
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63470 , vital:28414
- Description: Multimodal biometrics has become a popular means of overcoming the limitations of unimodal biometric systems. However, the rich information particular to the feature level is of a complex nature and leveraging its potential without overfitting a classifier is not well studied. This research investigates feature-classifier combinations on the fingerprint, face, palmprint, and iris modalities to effectively fuse their feature vectors for a complementary result. The effects of different feature-classifier combinations are thus isolated to identify novel or improved algorithms. A new face segmentation algorithm is shown to increase consistency in nominal and extreme scenarios. Moreover, two novel feature extraction techniques demonstrate better adaptation to dynamic lighting conditions, while reducing feature dimensionality to the benefit of classifiers. A comprehensive set of unimodal experiments are carried out to evaluate both verification and identification performance on a variety of datasets using four classifiers, namely Eigen, Fisher, Local Binary Pattern Histogram and linear Support Vector Machine on various feature extraction methods. The recognition performance of the proposed algorithms are shown to outperform the vast majority of related studies, when using the same dataset under the same test conditions. In the unimodal comparisons presented, the proposed approaches outperform existing systems even when given a handicap such as fewer training samples or data with a greater number of classes. A separate comprehensive set of experiments on feature fusion show that combining modality data provides a substantial increase in accuracy, with only a few exceptions that occur when differences in the image data quality of two modalities are substantial. However, when two poor quality datasets are fused, noticeable gains in recognition performance are realized when using the novel feature extraction approach. Finally, feature-fusion guidelines are proposed to provide the necessary insight to leverage the rich information effectively when fusing multiple biometric modalities at the feature level. These guidelines serve as the foundation to better understand and construct biometric systems that are effective in a variety of applications.
- Full Text:
- Date Issued: 2018
- Authors: Brown, Dane
- Date: 2018
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63470 , vital:28414
- Description: Multimodal biometrics has become a popular means of overcoming the limitations of unimodal biometric systems. However, the rich information particular to the feature level is of a complex nature and leveraging its potential without overfitting a classifier is not well studied. This research investigates feature-classifier combinations on the fingerprint, face, palmprint, and iris modalities to effectively fuse their feature vectors for a complementary result. The effects of different feature-classifier combinations are thus isolated to identify novel or improved algorithms. A new face segmentation algorithm is shown to increase consistency in nominal and extreme scenarios. Moreover, two novel feature extraction techniques demonstrate better adaptation to dynamic lighting conditions, while reducing feature dimensionality to the benefit of classifiers. A comprehensive set of unimodal experiments are carried out to evaluate both verification and identification performance on a variety of datasets using four classifiers, namely Eigen, Fisher, Local Binary Pattern Histogram and linear Support Vector Machine on various feature extraction methods. The recognition performance of the proposed algorithms are shown to outperform the vast majority of related studies, when using the same dataset under the same test conditions. In the unimodal comparisons presented, the proposed approaches outperform existing systems even when given a handicap such as fewer training samples or data with a greater number of classes. A separate comprehensive set of experiments on feature fusion show that combining modality data provides a substantial increase in accuracy, with only a few exceptions that occur when differences in the image data quality of two modalities are substantial. However, when two poor quality datasets are fused, noticeable gains in recognition performance are realized when using the novel feature extraction approach. Finally, feature-fusion guidelines are proposed to provide the necessary insight to leverage the rich information effectively when fusing multiple biometric modalities at the feature level. These guidelines serve as the foundation to better understand and construct biometric systems that are effective in a variety of applications.
- Full Text:
- Date Issued: 2018
Bioinformatics tool development with a focus on structural bioinformatics and the analysis of genetic variation in humans
- Authors: Brown, David K
- Date: 2018
- Subjects: Bioinformatics , Human genetics -- Variation , High performance computing , Workflow management systems , Molecular dynamics , Next generation sequencing , Human Mutation Analysis (HUMA)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60708 , vital:27820
- Description: This thesis is divided into three parts, united under the general theme of bioinformatics tool development and variation analysis. Part 1 describes the design and development of the Job Management System (JMS), a workflow management system for high performance computing (HPC). HPC has become an integral part of bioinformatics. Computational methods for molecular dynamics and next generation sequencing (NGS) analysis, which require complex calculations on large datasets, are not yet feasible on desktop computers. As such, powerful computer clusters have been employed to perform these calculations. However, making use of these HPC clusters requires familiarity with command line interfaces. This excludes a large number of researchers from taking advantage of these resources. JMS was developed as a tool to make it easier for researchers without a computer science background to make use of HPC. Additionally, JMS can be used to host computational tools and pipelines and generates both web-based interfaces and RESTful APIs for those tools. The web-based interfaces can be used to quickly and easily submit jobs to the underlying cluster. The RESTful web API, on the other hand, allows JMS to provided backend functionality for external tools and web servers that want to run jobs on the cluster. Numerous tools and workflows have already been added to JMS, several of which have been incorporated into external web servers. One such web server is the Human Mutation Analysis (HUMA) web server and database. HUMA, the topic of part 2 of this thesis, is a platform for the analysis of genetic variation in humans. HUMA aggregates data from various existing databases into a single, connected and related database. The advantages of this are realized in the powerful querying abilities that it provides. HUMA includes protein, gene, disease, and variation data and can be searched from the angle of any one of these categories. For example, searching for a protein will return the protein data (e.g. protein sequences, structures, domains and families, and other meta-data). However, the related nature of the database means that genes, diseases, variation, and literature related to the protein will also be returned, giving users a powerful and holistic view of all data associated with the protein. HUMA also provides links to the original sources of the data, allowing users to follow the links to find additional details. HUMA aims to be a platform for the analysis of genetic variation. As such, it also provides tools to visualize and analyse the data (several of which run on the underlying cluster, via JMS). These tools include alignment and 3D structure visualization, homology modeling, variant analysis, and the ability to upload custom variation datasets and map them to proteins, genes and diseases. HUMA also provides collaboration features, allowing users to share and discuss datasets and job results. Finally, part 3 of this thesis focused on the development of a suite of tools, MD-TASK, to analyse genetic variation at the protein structure level via network analysis of molecular dynamics simulations. The use of MD-TASK in combination with the tools developed in the previous parts of this thesis is showcased via the analysis of variation in the renin-angiotensinogen complex, a vital part of the renin-angiotensin system.
- Full Text:
- Date Issued: 2018
- Authors: Brown, David K
- Date: 2018
- Subjects: Bioinformatics , Human genetics -- Variation , High performance computing , Workflow management systems , Molecular dynamics , Next generation sequencing , Human Mutation Analysis (HUMA)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60708 , vital:27820
- Description: This thesis is divided into three parts, united under the general theme of bioinformatics tool development and variation analysis. Part 1 describes the design and development of the Job Management System (JMS), a workflow management system for high performance computing (HPC). HPC has become an integral part of bioinformatics. Computational methods for molecular dynamics and next generation sequencing (NGS) analysis, which require complex calculations on large datasets, are not yet feasible on desktop computers. As such, powerful computer clusters have been employed to perform these calculations. However, making use of these HPC clusters requires familiarity with command line interfaces. This excludes a large number of researchers from taking advantage of these resources. JMS was developed as a tool to make it easier for researchers without a computer science background to make use of HPC. Additionally, JMS can be used to host computational tools and pipelines and generates both web-based interfaces and RESTful APIs for those tools. The web-based interfaces can be used to quickly and easily submit jobs to the underlying cluster. The RESTful web API, on the other hand, allows JMS to provided backend functionality for external tools and web servers that want to run jobs on the cluster. Numerous tools and workflows have already been added to JMS, several of which have been incorporated into external web servers. One such web server is the Human Mutation Analysis (HUMA) web server and database. HUMA, the topic of part 2 of this thesis, is a platform for the analysis of genetic variation in humans. HUMA aggregates data from various existing databases into a single, connected and related database. The advantages of this are realized in the powerful querying abilities that it provides. HUMA includes protein, gene, disease, and variation data and can be searched from the angle of any one of these categories. For example, searching for a protein will return the protein data (e.g. protein sequences, structures, domains and families, and other meta-data). However, the related nature of the database means that genes, diseases, variation, and literature related to the protein will also be returned, giving users a powerful and holistic view of all data associated with the protein. HUMA also provides links to the original sources of the data, allowing users to follow the links to find additional details. HUMA aims to be a platform for the analysis of genetic variation. As such, it also provides tools to visualize and analyse the data (several of which run on the underlying cluster, via JMS). These tools include alignment and 3D structure visualization, homology modeling, variant analysis, and the ability to upload custom variation datasets and map them to proteins, genes and diseases. HUMA also provides collaboration features, allowing users to share and discuss datasets and job results. Finally, part 3 of this thesis focused on the development of a suite of tools, MD-TASK, to analyse genetic variation at the protein structure level via network analysis of molecular dynamics simulations. The use of MD-TASK in combination with the tools developed in the previous parts of this thesis is showcased via the analysis of variation in the renin-angiotensinogen complex, a vital part of the renin-angiotensin system.
- Full Text:
- Date Issued: 2018
A study of irradiation effects in solids
- Authors: Brown, Michael Ewart
- Date: 1966
- Subjects: Decomposition (Chemistry) , Crystals -- Thermal properties , Oxalates -- Thermal properties , Solids -- Effect of radiation on
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4509 , http://hdl.handle.net/10962/d1013387
- Description: One of the primary objects of this research was to determine, if possible, the nature of the radiation damage prior to thermal decomposition. The X-ray study has not wholly achieved this although more information has been derived from it than from similar work on AgMnO₄ However, the diffuse reflections obtained do indicate, quite strongly, the creation of point defects during irradiation. This is of value since such assumptions have been made in the explanation of the kinetics of decomposition of a number of irradiated solids (BaN₆,CaN₆). In addition the X-ray work has suggested future research which should produce useful information; namely, a precise study of the diffuse reflections. Another object of the research was to attempt to determine what characteristics, if any, of the kinetics of the decomposition of an unirradiated solid would predetermine a marked irradiation effect. It is obvious that the type of nuclear growth which occurs e.g. branching chain, or power law, does not characterise a substance with regard to a possible irradiation effect . The photosensitivity, or otherwise, also does not determine whether there will be an irradiation effect. However, the one property that the substances which have been studied, have in common, is a polyatomic anion, but here again ammonium dichromate does not show an acceleration of the decomposition after irradiation. Consequently it is considered that it is not possible to say, a priori, whether a solid will undergo an accelerated decomposition after irradiation. Each new solid, unless it belongs to a particular class e.g. the alkaline earth azides , must be considered afresh. Nevertheless it does appear that the irradiation effect can take two forms: - (i) the production of an unstable compound e.g. nickel oxalate, the decomposition of which affects the normal pyrolysis; and (ii) the production of point defects which determine the nature of the subsequent thermal decomposition e.g . CaN₆ . It is possible that the effect requires an interaction of the created point defects with the existing line defects.
- Full Text:
- Date Issued: 1966
- Authors: Brown, Michael Ewart
- Date: 1966
- Subjects: Decomposition (Chemistry) , Crystals -- Thermal properties , Oxalates -- Thermal properties , Solids -- Effect of radiation on
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4509 , http://hdl.handle.net/10962/d1013387
- Description: One of the primary objects of this research was to determine, if possible, the nature of the radiation damage prior to thermal decomposition. The X-ray study has not wholly achieved this although more information has been derived from it than from similar work on AgMnO₄ However, the diffuse reflections obtained do indicate, quite strongly, the creation of point defects during irradiation. This is of value since such assumptions have been made in the explanation of the kinetics of decomposition of a number of irradiated solids (BaN₆,CaN₆). In addition the X-ray work has suggested future research which should produce useful information; namely, a precise study of the diffuse reflections. Another object of the research was to attempt to determine what characteristics, if any, of the kinetics of the decomposition of an unirradiated solid would predetermine a marked irradiation effect. It is obvious that the type of nuclear growth which occurs e.g. branching chain, or power law, does not characterise a substance with regard to a possible irradiation effect . The photosensitivity, or otherwise, also does not determine whether there will be an irradiation effect. However, the one property that the substances which have been studied, have in common, is a polyatomic anion, but here again ammonium dichromate does not show an acceleration of the decomposition after irradiation. Consequently it is considered that it is not possible to say, a priori, whether a solid will undergo an accelerated decomposition after irradiation. Each new solid, unless it belongs to a particular class e.g. the alkaline earth azides , must be considered afresh. Nevertheless it does appear that the irradiation effect can take two forms: - (i) the production of an unstable compound e.g. nickel oxalate, the decomposition of which affects the normal pyrolysis; and (ii) the production of point defects which determine the nature of the subsequent thermal decomposition e.g . CaN₆ . It is possible that the effect requires an interaction of the created point defects with the existing line defects.
- Full Text:
- Date Issued: 1966
Genetic variation within and between some rare and common taxa of Cape Proteaceae and the implications for their conservation
- Authors: Brown, Susan Ann
- Date: 2000
- Subjects: Proteaceae -- South Africa Nature conservation -- South Africa Plant conservation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3905 , http://hdl.handle.net/10962/d1003964
- Full Text:
- Date Issued: 2000
- Authors: Brown, Susan Ann
- Date: 2000
- Subjects: Proteaceae -- South Africa Nature conservation -- South Africa Plant conservation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3905 , http://hdl.handle.net/10962/d1003964
- Full Text:
- Date Issued: 2000
The biology of Clarias Gariepinus (Burchell, 1822) in Lake Sibaya, Kwazulu, with emphasis on its role as a predator
- Authors: Bruton, Michael N
- Date: 1977
- Subjects: Catfishes -- South Africa -- KwaZulu-Natal -- Lake Sibaya. , Clarias , Clariidae
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: vital:5886 , http://hdl.handle.net/10962/d1013313
- Description: Aspects of the biology of the sharptooth catfish, Clarias gariepinus (Burchell, 1822) were studied in a clear coastal lake (Lake Sibaya, KwaZulu.). Catfish reach maturity towards the end of the first year (total length 200-250mm) and breed in summer. Gonadal maturation is cyclical, and most fishes are ripe between September. and January e ach year. Maturation stages and fecundity are described. Twenty-two catfish spawning runs were witnessed. There were no large aggregations of catfish before the Summer rains, as reported in some impoundments and rivers, but catfish accumulated on the shallow terrace immediately before a spawning run. Spawning usually took place in flooded marginal areas after heavy rain on dark calm nights. Peak activity occurred between 20h00 and 02h30. Pre-nuptial aggression, courtship and mating are described and illustrated in detail for the first time from field observations. Gonadal products are released while in amplexus and fertilized externally. The eggs have an adhesive disc for attachment to plants, and develop rapidly. Early development and feeding are described. The growth rate of catfish was determined using rings on the pectoral spines, and validated using recent techniques. C.gariepinus in Lake Sibaya grow rapidly and remain in good condition to a length of 500mm, but larger catfish have a poor growth rate and condition, and few exceed 650mm. The modal length and weight of the Sibaya population is intermediate between that of other populations but the number and condition of larger catfish in Lake Sibaya is lower. Other studies on C.gariepinus growth are reviewed. Very high and low first year increments obtained previously may be due to methodological errors, but catfish do appear to have variable growth rates. The size reached by C.gariepinus is reviewed. Catfish are equipped morphologically and behaviourally to feed on a wide variety of·prey in different situations, but they usually feed at night on exposed, active benthic organisms. Social hunting facilitates the capture of prey which is too fast or manoevrable for a single predator. Food preferences are scored by three different methods and presented for the total catfish population and for different length groups, seasons, and habitats. Juveniles feed more often and on a greater variety of prey, and their condition is better than that of adults. The proportions of several food items in the diet changed at different lake levels as marginal areas became inundated. In particular, increasing lake levels resulted in a change in relative density of three cichlid prey in the shallow water feeding area of catfish. This situation provided the opportunity to study the effect of changing cichlid density on predation by catfish. The world literature on factors influencing the predator-prey relationship in fish is reviewed and several key factors are identified. The interaction of fish predators and prey in Africa, and particularly Lake Sibaya, is examined in detail, and prey density, modified by accessibility, is found to be an important factor. The effect of cichlid prey density on catfish predation was therefore investigated using field collections and experimental observations. Catfish prey on the cichlid species with greatest relative abundance, with some deviations which can be explained in terms of accessibility. The experimental results also describe feeding periodicity, imitative hunting and the effect of water depth , day-night light intensity changes and predator number on predation efficiency on cichlids. Catfish predation is discussed in terms of recent predation theory, and it is concluded that their ability to switch from one prey to another as prey availability (= density+ accessibility) changes , is an an important aspect of their success as predators. Catfish predate more efficiently on invertebrates, but feed largely on fishes after the first year. This preference for fish prey is probably related to food quality, as fishes contributed over 75% of the energy content of all ingested food, as well as abundant protein and the correct amino acid balance. Finally, I conclude that the role of C.gariepinus as a predator on S.mossambicus is three-fold: (a) to enhance species' fitness by removing enfeebled individuals i.e. to act as a 'cleanser' (b) to restrict the distribution of prey under certain conditions i.e. act as a 'restricter' (c) to dampen fluctuations in cichlid abundance i.e. act as a 'regulator'. The relative importance of these roles may alter at different lake levels in Lake Sibaya in response to changes in the vulnerability of fish prey.
- Full Text:
- Date Issued: 1977
- Authors: Bruton, Michael N
- Date: 1977
- Subjects: Catfishes -- South Africa -- KwaZulu-Natal -- Lake Sibaya. , Clarias , Clariidae
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: vital:5886 , http://hdl.handle.net/10962/d1013313
- Description: Aspects of the biology of the sharptooth catfish, Clarias gariepinus (Burchell, 1822) were studied in a clear coastal lake (Lake Sibaya, KwaZulu.). Catfish reach maturity towards the end of the first year (total length 200-250mm) and breed in summer. Gonadal maturation is cyclical, and most fishes are ripe between September. and January e ach year. Maturation stages and fecundity are described. Twenty-two catfish spawning runs were witnessed. There were no large aggregations of catfish before the Summer rains, as reported in some impoundments and rivers, but catfish accumulated on the shallow terrace immediately before a spawning run. Spawning usually took place in flooded marginal areas after heavy rain on dark calm nights. Peak activity occurred between 20h00 and 02h30. Pre-nuptial aggression, courtship and mating are described and illustrated in detail for the first time from field observations. Gonadal products are released while in amplexus and fertilized externally. The eggs have an adhesive disc for attachment to plants, and develop rapidly. Early development and feeding are described. The growth rate of catfish was determined using rings on the pectoral spines, and validated using recent techniques. C.gariepinus in Lake Sibaya grow rapidly and remain in good condition to a length of 500mm, but larger catfish have a poor growth rate and condition, and few exceed 650mm. The modal length and weight of the Sibaya population is intermediate between that of other populations but the number and condition of larger catfish in Lake Sibaya is lower. Other studies on C.gariepinus growth are reviewed. Very high and low first year increments obtained previously may be due to methodological errors, but catfish do appear to have variable growth rates. The size reached by C.gariepinus is reviewed. Catfish are equipped morphologically and behaviourally to feed on a wide variety of·prey in different situations, but they usually feed at night on exposed, active benthic organisms. Social hunting facilitates the capture of prey which is too fast or manoevrable for a single predator. Food preferences are scored by three different methods and presented for the total catfish population and for different length groups, seasons, and habitats. Juveniles feed more often and on a greater variety of prey, and their condition is better than that of adults. The proportions of several food items in the diet changed at different lake levels as marginal areas became inundated. In particular, increasing lake levels resulted in a change in relative density of three cichlid prey in the shallow water feeding area of catfish. This situation provided the opportunity to study the effect of changing cichlid density on predation by catfish. The world literature on factors influencing the predator-prey relationship in fish is reviewed and several key factors are identified. The interaction of fish predators and prey in Africa, and particularly Lake Sibaya, is examined in detail, and prey density, modified by accessibility, is found to be an important factor. The effect of cichlid prey density on catfish predation was therefore investigated using field collections and experimental observations. Catfish prey on the cichlid species with greatest relative abundance, with some deviations which can be explained in terms of accessibility. The experimental results also describe feeding periodicity, imitative hunting and the effect of water depth , day-night light intensity changes and predator number on predation efficiency on cichlids. Catfish predation is discussed in terms of recent predation theory, and it is concluded that their ability to switch from one prey to another as prey availability (= density+ accessibility) changes , is an an important aspect of their success as predators. Catfish predate more efficiently on invertebrates, but feed largely on fishes after the first year. This preference for fish prey is probably related to food quality, as fishes contributed over 75% of the energy content of all ingested food, as well as abundant protein and the correct amino acid balance. Finally, I conclude that the role of C.gariepinus as a predator on S.mossambicus is three-fold: (a) to enhance species' fitness by removing enfeebled individuals i.e. to act as a 'cleanser' (b) to restrict the distribution of prey under certain conditions i.e. act as a 'restricter' (c) to dampen fluctuations in cichlid abundance i.e. act as a 'regulator'. The relative importance of these roles may alter at different lake levels in Lake Sibaya in response to changes in the vulnerability of fish prey.
- Full Text:
- Date Issued: 1977
Analysing emergent time within an isolated Universe through the application of interactions in the conditional probability approach
- Authors: Bryan, Kate Louise Halse
- Date: 2020
- Subjects: Space and time , Quantum gravity , Quantum theory , Relativity (Physics)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146676 , vital:38547
- Description: Time remains a frequently discussed issue in physics and philosophy. One interpretation of growing popularity is the ‘timeless’ view which states that our experience of time is only an illusion. The isolated Universe model, provided by the Wheeler-DeWitt equation, supports this interpretation by describing time using clocks in the conditional probability interpretation (CPI). However, the CPI customarily dismisses interaction effects as negligible creating a potential blind spot which overlooks the potential influence of interaction effects. Accounting for interactions opens up a new avenue of analysis and a potential challenge to the interpretation of time. In aid of our assessment of the impact interaction effects have on the CPI, we present rudimentary definitions of time and its associated concepts. Defined in a minimalist manner, time is argued to require a postulate of causality as a means of accounting for temporal ordering in physical theories. Several of these theories are discussed here in terms of their respective approaches to time and, despite their differences, there are indications that the accounts of time are unified in a more fundamental theory. An analytic analysis of the CPI, incorporating two different clock choices, and a qualitative analysis both confirm that interactions have a necessary role within the CPI. The consequence of removing interactions is a maximised uncertainty in any measurement of the clock and a restriction to a two-state system, as indicated by the results of the toy models and qualitative argument respectively. The philosophical implication is that we are not restricted to the timeless view since including interactions as agents of causal interventions between systems provides an account of time as a real phenomenon. This result highlights the reliance on a postulate of causality which forms a pressing problem in explaining our experience of time.
- Full Text:
- Date Issued: 2020
- Authors: Bryan, Kate Louise Halse
- Date: 2020
- Subjects: Space and time , Quantum gravity , Quantum theory , Relativity (Physics)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146676 , vital:38547
- Description: Time remains a frequently discussed issue in physics and philosophy. One interpretation of growing popularity is the ‘timeless’ view which states that our experience of time is only an illusion. The isolated Universe model, provided by the Wheeler-DeWitt equation, supports this interpretation by describing time using clocks in the conditional probability interpretation (CPI). However, the CPI customarily dismisses interaction effects as negligible creating a potential blind spot which overlooks the potential influence of interaction effects. Accounting for interactions opens up a new avenue of analysis and a potential challenge to the interpretation of time. In aid of our assessment of the impact interaction effects have on the CPI, we present rudimentary definitions of time and its associated concepts. Defined in a minimalist manner, time is argued to require a postulate of causality as a means of accounting for temporal ordering in physical theories. Several of these theories are discussed here in terms of their respective approaches to time and, despite their differences, there are indications that the accounts of time are unified in a more fundamental theory. An analytic analysis of the CPI, incorporating two different clock choices, and a qualitative analysis both confirm that interactions have a necessary role within the CPI. The consequence of removing interactions is a maximised uncertainty in any measurement of the clock and a restriction to a two-state system, as indicated by the results of the toy models and qualitative argument respectively. The philosophical implication is that we are not restricted to the timeless view since including interactions as agents of causal interventions between systems provides an account of time as a real phenomenon. This result highlights the reliance on a postulate of causality which forms a pressing problem in explaining our experience of time.
- Full Text:
- Date Issued: 2020
Shakespeare's early comedies: studies in The comedy of errors, The taming of the shrew and The two gentlemen of Verona
- Authors: Bryant, Peter
- Date: 1970
- Subjects: Shakespeare, William, 1564-1616. Comedy of Errors Shakespeare, William, 1564-1616. Comedies Shakespeare, William, 1564-1616. Two gentlemen of Verona Shakespeare, William, 1564-1616. Taming of the shrew
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2291 , http://hdl.handle.net/10962/d1009964
- Description: This dissertation offers fairly full readings of three early Shakespearean comedies. Because these works are still partly misunderstood, it has seemed reasonable to lay the critical emphasis on explication, though a certain amount of judging has been inevitable. The aim has been to induce recognition of aspects of these plays to which much modern criticism has seemed opaque.
- Full Text:
- Date Issued: 1970
- Authors: Bryant, Peter
- Date: 1970
- Subjects: Shakespeare, William, 1564-1616. Comedy of Errors Shakespeare, William, 1564-1616. Comedies Shakespeare, William, 1564-1616. Two gentlemen of Verona Shakespeare, William, 1564-1616. Taming of the shrew
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2291 , http://hdl.handle.net/10962/d1009964
- Description: This dissertation offers fairly full readings of three early Shakespearean comedies. Because these works are still partly misunderstood, it has seemed reasonable to lay the critical emphasis on explication, though a certain amount of judging has been inevitable. The aim has been to induce recognition of aspects of these plays to which much modern criticism has seemed opaque.
- Full Text:
- Date Issued: 1970
An evaluation of the potential for implementing adaptive co-management in the Waodani social-ecological system in the Ecuadorian Amazon
- Authors: Bryja, Malgorzata Anna
- Date: 2015
- Subjects: Adaptive natural resource management -- Ecuador -- Reserva de Biosfera Yasuni , Huao Indians -- Ecuador -- Reserva de Biosfera Yasuni , Natural resources -- Co-management -- Ecuador -- Reserva de Biosfera Yasuni , Social ecology -- Ecuador -- Reserva de Biosfera Yasuni , Sustainable development -- Ecuador -- Reserva de Biosfera Yasuni , Resource-based communities -- Ecuador -- Reserva de Biosfera Yasuni , Reserva de Biosfera Yasuni (Ecuador) -- Economic conditions , Huao Indians -- Ecuador -- Reserva de Biosfera Yasuni -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4784 , http://hdl.handle.net/10962/d1018192
- Description: Adaptive co-management (ACM), one of the most prominent management approaches to emerge in the recent years, combines iterative learning, flexibility, and adaptation promoted by adaptive management with the principles of nurturing diversity and fostering collaboration among different partners that underpin co-management philosophy. ACM has been proposed as an approach to address the deficiencies of centralized management in ensuring sustainability of social-ecological systems (SESs) in face of future uncertainties. This thesis aims to evaluate the readiness of resource users (the Waodani) as well as external actors (the Ecuadorian State and NGOs) for future implementation of ACM and thus enhancing the long-term social-ecological sustainability of the Waodani SES located in the Yasuni Biosphere Reserve in the Ecuadorian Amazon. Qualitative data obtained by means of focus groups with the Waodani and individual interviews with external actors and Waodani leaders revealed different levels of readiness for ACM. Firstly, in the case of the Waodani, the insufficient fulfillment of some conditions required for successful ACM as well as intercommunity differences in regards to these conditions can complicate the implementation of ACM, unless sufficient external assistance is offered to the SES. The analysis of NGOs demonstrated, on the other hand, a relative readiness for ACM, providing that such aspects as sufficient funding, long-term commitment to collaboration, and inter-institutional linkages are strengthened. The study also found that the Ecuadorian government’s potential to contribute to ACM is hindered by the lack of readiness to work with the indigenous society as well as by funding and communication challenges. Furthermore, the resource based economy supported by the State limits the scope of innovation and adaptation. Still, as in the case of other actors, overcoming the challenges and transitioning towards adaptive governance and thus ACM could be possible in the long-term, if recent legal and political changes are truly implemented.
- Full Text:
- Date Issued: 2015
- Authors: Bryja, Malgorzata Anna
- Date: 2015
- Subjects: Adaptive natural resource management -- Ecuador -- Reserva de Biosfera Yasuni , Huao Indians -- Ecuador -- Reserva de Biosfera Yasuni , Natural resources -- Co-management -- Ecuador -- Reserva de Biosfera Yasuni , Social ecology -- Ecuador -- Reserva de Biosfera Yasuni , Sustainable development -- Ecuador -- Reserva de Biosfera Yasuni , Resource-based communities -- Ecuador -- Reserva de Biosfera Yasuni , Reserva de Biosfera Yasuni (Ecuador) -- Economic conditions , Huao Indians -- Ecuador -- Reserva de Biosfera Yasuni -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4784 , http://hdl.handle.net/10962/d1018192
- Description: Adaptive co-management (ACM), one of the most prominent management approaches to emerge in the recent years, combines iterative learning, flexibility, and adaptation promoted by adaptive management with the principles of nurturing diversity and fostering collaboration among different partners that underpin co-management philosophy. ACM has been proposed as an approach to address the deficiencies of centralized management in ensuring sustainability of social-ecological systems (SESs) in face of future uncertainties. This thesis aims to evaluate the readiness of resource users (the Waodani) as well as external actors (the Ecuadorian State and NGOs) for future implementation of ACM and thus enhancing the long-term social-ecological sustainability of the Waodani SES located in the Yasuni Biosphere Reserve in the Ecuadorian Amazon. Qualitative data obtained by means of focus groups with the Waodani and individual interviews with external actors and Waodani leaders revealed different levels of readiness for ACM. Firstly, in the case of the Waodani, the insufficient fulfillment of some conditions required for successful ACM as well as intercommunity differences in regards to these conditions can complicate the implementation of ACM, unless sufficient external assistance is offered to the SES. The analysis of NGOs demonstrated, on the other hand, a relative readiness for ACM, providing that such aspects as sufficient funding, long-term commitment to collaboration, and inter-institutional linkages are strengthened. The study also found that the Ecuadorian government’s potential to contribute to ACM is hindered by the lack of readiness to work with the indigenous society as well as by funding and communication challenges. Furthermore, the resource based economy supported by the State limits the scope of innovation and adaptation. Still, as in the case of other actors, overcoming the challenges and transitioning towards adaptive governance and thus ACM could be possible in the long-term, if recent legal and political changes are truly implemented.
- Full Text:
- Date Issued: 2015
The adsorption of chelating reagents on oxide minerals
- Bryson, Michael Andrew Walker
- Authors: Bryson, Michael Andrew Walker
- Date: 1986
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:20969 , http://hdl.handle.net/10962/5729
- Description: This work constitutes a fundamental study of the interaction between chelating reagents and oxide minerals . The adsorption mechanisms have been elucidated for most of the systems generated by the oxides of copper(II) or iron(III) and chelating reagents octyl hydroxamate, N-phenylbenzohydroxamate, salicylaldoxime, 5-nitrosalicylaldoxime or 8-hydroxyquinoline. The results of the preliminary work on one of the systems, viz. the oxide-hydroxamate system, indicated that the classical type adsorption process, in which the reagent forms a uniform layer of chelate over the oxide surface was not applicable. Rather, the adsorption occurred via the formation of a discrete metal-chelate precipitate at the oxide surface. In order to better understand the associated with copper (II) oxide, adsorption process the oxide was recrystallized to produce a coarser material with a more uniform surface. This allowed the oxide surface to be viewed under the scanning electron microscope and also enabled the relative concentration of "surface" and "bulk" chelate to be assessed. A detailed investigation of the effect of the system variables; pH, conditioning period, concentration, temperature, surface area and dispersing reagent on the rate of precipitation of the copper chelate species of general form, Cu(chel)2' was made. In addition the chemical nature of the adsorbed species and the structural form of the precipitates were determined with the aid of infra-red spectroscopy and the scanning electron microscope. On the basis of these results a model has been formulated for the adsorption processes. In this model the adsorption dissolution, is considered to occur in stages: 1. Oxide dissolution, 2. metal complex formation, 3. Metal chelate precipitation at the oxide surface and 4. “bulk” chelate formation by post-precipitation processes. The precipitation process was examined in more detail by the study of the adsorption of chelate on copper metal. The results of this study showed that it was possible to relate the structural type of precipitate formed, ie. fibrous or platelike, to the degree of supersaturation of the metal complex in solution. Furthermore, it was found that the precipitate structure determined whether it remained attached to the surface or detached. Contact angle measurements of air bubbles on copper metal conditioned with chelate were related to the adsorption results in an attempt to isolate the optimum conditions for flotation of oxide minerals.
- Full Text:
- Date Issued: 1986
- Authors: Bryson, Michael Andrew Walker
- Date: 1986
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:20969 , http://hdl.handle.net/10962/5729
- Description: This work constitutes a fundamental study of the interaction between chelating reagents and oxide minerals . The adsorption mechanisms have been elucidated for most of the systems generated by the oxides of copper(II) or iron(III) and chelating reagents octyl hydroxamate, N-phenylbenzohydroxamate, salicylaldoxime, 5-nitrosalicylaldoxime or 8-hydroxyquinoline. The results of the preliminary work on one of the systems, viz. the oxide-hydroxamate system, indicated that the classical type adsorption process, in which the reagent forms a uniform layer of chelate over the oxide surface was not applicable. Rather, the adsorption occurred via the formation of a discrete metal-chelate precipitate at the oxide surface. In order to better understand the associated with copper (II) oxide, adsorption process the oxide was recrystallized to produce a coarser material with a more uniform surface. This allowed the oxide surface to be viewed under the scanning electron microscope and also enabled the relative concentration of "surface" and "bulk" chelate to be assessed. A detailed investigation of the effect of the system variables; pH, conditioning period, concentration, temperature, surface area and dispersing reagent on the rate of precipitation of the copper chelate species of general form, Cu(chel)2' was made. In addition the chemical nature of the adsorbed species and the structural form of the precipitates were determined with the aid of infra-red spectroscopy and the scanning electron microscope. On the basis of these results a model has been formulated for the adsorption processes. In this model the adsorption dissolution, is considered to occur in stages: 1. Oxide dissolution, 2. metal complex formation, 3. Metal chelate precipitation at the oxide surface and 4. “bulk” chelate formation by post-precipitation processes. The precipitation process was examined in more detail by the study of the adsorption of chelate on copper metal. The results of this study showed that it was possible to relate the structural type of precipitate formed, ie. fibrous or platelike, to the degree of supersaturation of the metal complex in solution. Furthermore, it was found that the precipitate structure determined whether it remained attached to the surface or detached. Contact angle measurements of air bubbles on copper metal conditioned with chelate were related to the adsorption results in an attempt to isolate the optimum conditions for flotation of oxide minerals.
- Full Text:
- Date Issued: 1986
Characterization of friction hydro pillar process weld properties as applied to 10CrMo910 creep resistant steel for application in the power generation Industry
- Authors: Bulbring, Daniel Louis Hans
- Subjects: Materials -- Creep , Friction welding
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9636 , http://hdl.handle.net/10948/d1020586
- Description: Creep degradation of steam carrying vessels in the power generation industry is a concern that needs to be constantly monitored. The Weldcore® process has been earmarked as a potential method of creep sampling which will allow for thick-walled sections to be analysed. A component of the process involves plugging the resultant hole after removing a creep sample using a novel welding technique called friction hydro pillar processing. At the commencement of this study, insufficient data was available to warrant safe industrial application of the process. This research was conducted to evaluate the performance of 10CrMo910 friction hydro pillar process welds. The effects of downward force, stud taper angle, hole taper angle and hole base diameter on process response, defect population, static properties and dynamic performance were evaluated. The variation of downward force showed that higher forces produce significantly smaller defects and higher fatigue life. The occurrence of defects was linked to process parameters and geometry thereby identifying the correct parameters for safe use in the power generation industry. Flash formation was identified as an early indicator of weld defects and can assist with quality control in industrial applications. Methods of standardising the plunge depth and forge force were developed to identify the correct magnitudes for different geometries, without the need for testing. Defects were shown to populate specific regions of the weld and produce variations in fatigue life. Crack initiation sites were detected which will aid in identifying areas of focus in further research and development. Temperature measurements were linked to the occurrence of defects and crack initiation sites and have been identified as a method of identifying defective welds. The effects of process parameters and stud and hole taper angles on energy inputs and near interface temperatures were statistically evaluated. Downward force was shown to have the largest effect on energy input rates, total energy input and temperatures at the 11.5mm and 20.5mm positions. Smaller hole and stud taper angles produced lower energy inputs and were identified as more energy efficient than the larger taper angles. A regression model was also developed to predict the fatigue life of welds and can assist with critical process related decision making. A range of hole base diameters were identified which produced welds with low defect populations and fatigue performance similar to that of the parent plate. Larger hole base diameters were shown to produce significant defects along the hole bottom fillet, in the weld nugget and along the bond line. Temperature measurements of the larger diameter welds showed a delay in response and are attributed to a delayed contact of plasticised stud material with the sidewall. Welds with hole base diameters larger than 11mm produced unrepeatable and defective welds, and also required higher energy inputs making smaller diameters more desirable. Analysis of all welds in this study revealed that clearance and interfacial pressures characterise the quality of friction hydro pillar process welds, therefore models were developed to aid in critical decision making with respect to downward force and geometry. This study has successfully evaluated the effects of process parameters and geometry on the properties of friction hydro pillar process welds and thereby has increased understanding of the process.
- Full Text:
- Authors: Bulbring, Daniel Louis Hans
- Subjects: Materials -- Creep , Friction welding
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9636 , http://hdl.handle.net/10948/d1020586
- Description: Creep degradation of steam carrying vessels in the power generation industry is a concern that needs to be constantly monitored. The Weldcore® process has been earmarked as a potential method of creep sampling which will allow for thick-walled sections to be analysed. A component of the process involves plugging the resultant hole after removing a creep sample using a novel welding technique called friction hydro pillar processing. At the commencement of this study, insufficient data was available to warrant safe industrial application of the process. This research was conducted to evaluate the performance of 10CrMo910 friction hydro pillar process welds. The effects of downward force, stud taper angle, hole taper angle and hole base diameter on process response, defect population, static properties and dynamic performance were evaluated. The variation of downward force showed that higher forces produce significantly smaller defects and higher fatigue life. The occurrence of defects was linked to process parameters and geometry thereby identifying the correct parameters for safe use in the power generation industry. Flash formation was identified as an early indicator of weld defects and can assist with quality control in industrial applications. Methods of standardising the plunge depth and forge force were developed to identify the correct magnitudes for different geometries, without the need for testing. Defects were shown to populate specific regions of the weld and produce variations in fatigue life. Crack initiation sites were detected which will aid in identifying areas of focus in further research and development. Temperature measurements were linked to the occurrence of defects and crack initiation sites and have been identified as a method of identifying defective welds. The effects of process parameters and stud and hole taper angles on energy inputs and near interface temperatures were statistically evaluated. Downward force was shown to have the largest effect on energy input rates, total energy input and temperatures at the 11.5mm and 20.5mm positions. Smaller hole and stud taper angles produced lower energy inputs and were identified as more energy efficient than the larger taper angles. A regression model was also developed to predict the fatigue life of welds and can assist with critical process related decision making. A range of hole base diameters were identified which produced welds with low defect populations and fatigue performance similar to that of the parent plate. Larger hole base diameters were shown to produce significant defects along the hole bottom fillet, in the weld nugget and along the bond line. Temperature measurements of the larger diameter welds showed a delay in response and are attributed to a delayed contact of plasticised stud material with the sidewall. Welds with hole base diameters larger than 11mm produced unrepeatable and defective welds, and also required higher energy inputs making smaller diameters more desirable. Analysis of all welds in this study revealed that clearance and interfacial pressures characterise the quality of friction hydro pillar process welds, therefore models were developed to aid in critical decision making with respect to downward force and geometry. This study has successfully evaluated the effects of process parameters and geometry on the properties of friction hydro pillar process welds and thereby has increased understanding of the process.
- Full Text:
Financial characteristics of the nonprofit organisation: theory and evidence for the assessment of the financial condition of South African public universities
- Authors: Bunting, Mark Bevan
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:923 , http://hdl.handle.net/10962/d1021298 , http://orcid.org/0000-0002-3392-554X
- Description: In this thesis, an analytical framework is developed for the assessment of the financial condition of South African public universities. Foundational constructs of nonprofit economics are applied in the consideration of financial theories of nonprofit organisations in general, and public universities in particular. From this review, a number of hypotheses are developed. Each of these specifies a positive or negative association between a university's financial condition and a particular dimension of its assets, liabilities, equity, revenues, expenses and surplus. From the nonprofit financial analysis literature, ratios and indicators relevant to these hypotheses are selected. Audited data from the annual financial statements of the universities for the seven year period 2007 to 2013 are substantially transformed in mitigation of failures in accounting, auditing and accountability. The adjusted accounting numbers are used to calculate the financial indicators applicable to each university. Exploratory factor analysis is implemented to categorise and organise this large indicator set on the basis of identified associations with a smaller number of factors. It is found that the financial condition of South African public universities is defined by two broad financial characteristics, capital and revenue. Assessment of the capital dimension is informed by a focus on institutional equity, with particular emphasis on expendable equity and its proportionate relationships with surplus, total capital, and total expenses. The revenue dimension is appropriately evaluated in the context of a comparative and interactive consideration of the three main components of South African public university revenue, as well as the proportionate relationship between non-staff operating expenses and total expenses. The framework displays considerable levels of stability and consistency over the seven year review period, and its constructs are, in addition, robust to the application of multiple alternative confirmatory tests involving financial data that are independent of the factor solutions. The financial condition assessment framework developed in this thesis offers a contribution to a broader discourse in nonprofit finance and accounting, with a focus on public university finances.
- Full Text:
- Date Issued: 2016
- Authors: Bunting, Mark Bevan
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:923 , http://hdl.handle.net/10962/d1021298 , http://orcid.org/0000-0002-3392-554X
- Description: In this thesis, an analytical framework is developed for the assessment of the financial condition of South African public universities. Foundational constructs of nonprofit economics are applied in the consideration of financial theories of nonprofit organisations in general, and public universities in particular. From this review, a number of hypotheses are developed. Each of these specifies a positive or negative association between a university's financial condition and a particular dimension of its assets, liabilities, equity, revenues, expenses and surplus. From the nonprofit financial analysis literature, ratios and indicators relevant to these hypotheses are selected. Audited data from the annual financial statements of the universities for the seven year period 2007 to 2013 are substantially transformed in mitigation of failures in accounting, auditing and accountability. The adjusted accounting numbers are used to calculate the financial indicators applicable to each university. Exploratory factor analysis is implemented to categorise and organise this large indicator set on the basis of identified associations with a smaller number of factors. It is found that the financial condition of South African public universities is defined by two broad financial characteristics, capital and revenue. Assessment of the capital dimension is informed by a focus on institutional equity, with particular emphasis on expendable equity and its proportionate relationships with surplus, total capital, and total expenses. The revenue dimension is appropriately evaluated in the context of a comparative and interactive consideration of the three main components of South African public university revenue, as well as the proportionate relationship between non-staff operating expenses and total expenses. The framework displays considerable levels of stability and consistency over the seven year review period, and its constructs are, in addition, robust to the application of multiple alternative confirmatory tests involving financial data that are independent of the factor solutions. The financial condition assessment framework developed in this thesis offers a contribution to a broader discourse in nonprofit finance and accounting, with a focus on public university finances.
- Full Text:
- Date Issued: 2016
Beyond all words : a psychoanalytic approach to the phenomenon of mysticism in literature
- Authors: Bunyan, David Christopher
- Date: 1991
- Subjects: Mysticism in literature Mysticism -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2242 , http://hdl.handle.net/10962/d1002285
- Description: The principal claim of this thesis is that the mystical experience is a wide-ranging influence upon literature. It is a recurrent thematic concern of poets, novelists and playwrights; but even when mysticism is not an overt element in a text, analysis of its symbols can reveal references to emotions and experiences of a mystical character - as is frequently the case with fantasy. In a more essential way, certain widely-used techniques of poetry effectively reproduce the character of mystical events for the reader. Some theory does indeed imply that the mystical bearing is quite fundamental, at a certain level, to all creative literature. This thesis explores the link between mysticism and literature through widely differing examples, to show how it continues to be found in otherwise divergent texts and contexts. Indeed, no attempt is made to provide an exhaustive overview; rather, certain special areas of interest are represented by selected cases. Mystical elements in Modernism, for example (especially in T.S. Eliot and Virginia Woolf), are contrasted with Romantic attitudes to mysticism, which Wordsworth and Coleridge are taken to represent. A further goal is to analyse the character of literary mysticism, and to account for the connection between mysticism and literary practice. The view is adopted that the circumstances in which the infant first acquires language is of crucial importance in this regard, and that literary language often draws upon submerged recollections of these early circumstances. Literature, it is argued, can employ signs and patterns of symbolisation in ways that actually attempt to 'undo' many of the everyday functions of words. The ultimate ideal of such literary techniques is to 'reverse' the process by which language was acquired and to 'return' the reader to a state resembling pre-linguistic experience, a goal which has much in common with the ambitions of mystics. Jacques Lacan's theoretical writings touch at many points upon the early development of the child and the significance of its acquisition of language. This thesis consequently has recourse to Lacan's work and, where relevant, to related psychoanalytic writings by Sigmund Freud and Julia Kristeva. After an investigation of the main characteristics of mystical experience as such, the Introduction broadly outlines Lacan's theoretical position. Chapter 1 is concerned more specifically with Lacan's discussions of mysticism. Part Two (Chapters 2-4) deals principally with the links between mystical yearnings and the Romantic ideal of the 'sublime'. In Part Three (Chapters 5-7) the relation between mysticism and Modernist developments affecting both theme and artistic technique is examined in works by three writers: T.S. Eliot, Virginia Woolf, and Fernando Pessoa. Part Four discusses particular literary presentations of 'evil' and of 'good' as embodiments of mystical perceptions. Late nineteenth- and early twentieth-century 'supernatural' fiction is selected to represent the first case, and certain New Testament and early Christian texts the second.
- Full Text:
- Date Issued: 1991
- Authors: Bunyan, David Christopher
- Date: 1991
- Subjects: Mysticism in literature Mysticism -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2242 , http://hdl.handle.net/10962/d1002285
- Description: The principal claim of this thesis is that the mystical experience is a wide-ranging influence upon literature. It is a recurrent thematic concern of poets, novelists and playwrights; but even when mysticism is not an overt element in a text, analysis of its symbols can reveal references to emotions and experiences of a mystical character - as is frequently the case with fantasy. In a more essential way, certain widely-used techniques of poetry effectively reproduce the character of mystical events for the reader. Some theory does indeed imply that the mystical bearing is quite fundamental, at a certain level, to all creative literature. This thesis explores the link between mysticism and literature through widely differing examples, to show how it continues to be found in otherwise divergent texts and contexts. Indeed, no attempt is made to provide an exhaustive overview; rather, certain special areas of interest are represented by selected cases. Mystical elements in Modernism, for example (especially in T.S. Eliot and Virginia Woolf), are contrasted with Romantic attitudes to mysticism, which Wordsworth and Coleridge are taken to represent. A further goal is to analyse the character of literary mysticism, and to account for the connection between mysticism and literary practice. The view is adopted that the circumstances in which the infant first acquires language is of crucial importance in this regard, and that literary language often draws upon submerged recollections of these early circumstances. Literature, it is argued, can employ signs and patterns of symbolisation in ways that actually attempt to 'undo' many of the everyday functions of words. The ultimate ideal of such literary techniques is to 'reverse' the process by which language was acquired and to 'return' the reader to a state resembling pre-linguistic experience, a goal which has much in common with the ambitions of mystics. Jacques Lacan's theoretical writings touch at many points upon the early development of the child and the significance of its acquisition of language. This thesis consequently has recourse to Lacan's work and, where relevant, to related psychoanalytic writings by Sigmund Freud and Julia Kristeva. After an investigation of the main characteristics of mystical experience as such, the Introduction broadly outlines Lacan's theoretical position. Chapter 1 is concerned more specifically with Lacan's discussions of mysticism. Part Two (Chapters 2-4) deals principally with the links between mystical yearnings and the Romantic ideal of the 'sublime'. In Part Three (Chapters 5-7) the relation between mysticism and Modernist developments affecting both theme and artistic technique is examined in works by three writers: T.S. Eliot, Virginia Woolf, and Fernando Pessoa. Part Four discusses particular literary presentations of 'evil' and of 'good' as embodiments of mystical perceptions. Late nineteenth- and early twentieth-century 'supernatural' fiction is selected to represent the first case, and certain New Testament and early Christian texts the second.
- Full Text:
- Date Issued: 1991
Purification and characterization of TbHsp70.c, a novel Hsp70 from Trypanosoma brucei
- Authors: Burger, Adélle
- Date: 2014
- Subjects: African trypanosomiasis -- Research Heat shock proteins -- Research Trypanosoma brucei -- Research Mycobacterial diseases -- Research -- Africa Parasitic diseases -- Africa -- Prevention Parasites -- Physiology Developing countries -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4105 , http://hdl.handle.net/10962/d1011618
- Description: One of Africa’s neglected tropical diseases, African Trypanosomiasis, is not only fatal but also has a crippling impact on economic development. Heat shock proteins play a wide range of roles in the cell and they are required to assist the parasite as it moves from a cold blooded insect vector to a warm blooded mammalian host. The expression of heat shock proteins increases during these heat shock conditions, and this is considered to play a role in differentiation of these vector-borne parasites. Heat shock protein 70 (Hsp70) is an important molecular chaperone that is involved in protein homeostasis, Hsp40 acts as a co-chaperone and stimulates its intrinsically weak ATPase activity. In silico analysis of the T. brucei genome has revealed the existence of 12 Hsp70 proteins and 65 Hsp40 proteins to date. A novel Hsp70, TbHsp70.c, was recently identified in T. brucei. Different from the prototypical Hsp70, TbHsp70.c contains an acidic substrate binding domain and lacks the C-terminal EEVD motif. By implication the substrate range and mechanism by which the substrates are recognized may be novel. The ability of a Type I Hsp40, Tbj2, to function as a co-chaperone of TbHsp70.c was investigated. The main objective of this study was to biochemically characterize TbHsp70.c and its partnership with Tbj2 to further enhance our knowledge of parasite biology. TbHsp70.c and Tbj2 were heterologously expressed and purified and both proteins displayed chaperone activities in their ability to suppress aggregation of thermolabile MDH. TbHsp70.c also suppressed aggregation of rhodanese. ATPase assays revealed that the ATPase activity of TbHsp70.c was stimulated by Tbj2. The targeted inhibition of the function of heat shock proteins is emerging as a tool to combat disease. The small molecule modulators quercetin and methylene blue are known to inhibit the ATPase activity of Hsp70. However, methylene blue did not significantly inhibit the ATPase activity of TbHsp70.c; while quercetin, did inhibit the ATPase activity. In vivo heat stress experiments indicated an up-regulation of the expression levels of TbHsp70.c. RNA interference studies showed partial knockdown of TbHsp70.c with no detrimental effect on the parasite. Fluorescence microscopy studies of TbHsp70.c showed a probable cytoplasmic subcellular localization. In this study both TbHsp70.c and Tbj2 demonstrated chaperone activity and Tbj2 possibly functions as a co-chaperone of TbHsp70.c.
- Full Text:
- Date Issued: 2014
- Authors: Burger, Adélle
- Date: 2014
- Subjects: African trypanosomiasis -- Research Heat shock proteins -- Research Trypanosoma brucei -- Research Mycobacterial diseases -- Research -- Africa Parasitic diseases -- Africa -- Prevention Parasites -- Physiology Developing countries -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4105 , http://hdl.handle.net/10962/d1011618
- Description: One of Africa’s neglected tropical diseases, African Trypanosomiasis, is not only fatal but also has a crippling impact on economic development. Heat shock proteins play a wide range of roles in the cell and they are required to assist the parasite as it moves from a cold blooded insect vector to a warm blooded mammalian host. The expression of heat shock proteins increases during these heat shock conditions, and this is considered to play a role in differentiation of these vector-borne parasites. Heat shock protein 70 (Hsp70) is an important molecular chaperone that is involved in protein homeostasis, Hsp40 acts as a co-chaperone and stimulates its intrinsically weak ATPase activity. In silico analysis of the T. brucei genome has revealed the existence of 12 Hsp70 proteins and 65 Hsp40 proteins to date. A novel Hsp70, TbHsp70.c, was recently identified in T. brucei. Different from the prototypical Hsp70, TbHsp70.c contains an acidic substrate binding domain and lacks the C-terminal EEVD motif. By implication the substrate range and mechanism by which the substrates are recognized may be novel. The ability of a Type I Hsp40, Tbj2, to function as a co-chaperone of TbHsp70.c was investigated. The main objective of this study was to biochemically characterize TbHsp70.c and its partnership with Tbj2 to further enhance our knowledge of parasite biology. TbHsp70.c and Tbj2 were heterologously expressed and purified and both proteins displayed chaperone activities in their ability to suppress aggregation of thermolabile MDH. TbHsp70.c also suppressed aggregation of rhodanese. ATPase assays revealed that the ATPase activity of TbHsp70.c was stimulated by Tbj2. The targeted inhibition of the function of heat shock proteins is emerging as a tool to combat disease. The small molecule modulators quercetin and methylene blue are known to inhibit the ATPase activity of Hsp70. However, methylene blue did not significantly inhibit the ATPase activity of TbHsp70.c; while quercetin, did inhibit the ATPase activity. In vivo heat stress experiments indicated an up-regulation of the expression levels of TbHsp70.c. RNA interference studies showed partial knockdown of TbHsp70.c with no detrimental effect on the parasite. Fluorescence microscopy studies of TbHsp70.c showed a probable cytoplasmic subcellular localization. In this study both TbHsp70.c and Tbj2 demonstrated chaperone activity and Tbj2 possibly functions as a co-chaperone of TbHsp70.c.
- Full Text:
- Date Issued: 2014
A historical study of John Graham Lake and South African/United States pentecostalism
- Authors: Burpeau, Kemp Pendleton
- Date: 2002
- Subjects: Lake, John G , Pentecostalism -- South Africa , Pentecostalism -- United States , Pentecostals , Christianity and politics -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2587 , http://hdl.handle.net/10962/d1006484 , Lake, John G , Pentecostalism -- South Africa , Pentecostalism -- United States , Pentecostals , Christianity and politics -- South Africa
- Description: American minister John Graham Lake (1870-1935) was a pivotal participant in an era of profound religious and political transition. Surprisingly, Lake's often provocative life had previously been largely neglected as a field of academic inquiry. In the U.S. Lake associated with key Holiness, Wesleyan and Apostolic Faith charismatics like John Alexander Dowie of the Zion City, Illinois Utopia, Charles Parham of the Topeka Revival and William Seymour of the Azusa Street Revival. Lake served as an important intermediary between Parham's often reactionary, white orientation that was unreceptive to an enthusiastic black liturgy and Seymour's expansive African-American egalitarianism expressed through exuberant spirit manifestations. Lake's South African ministry was shaped by his middle class white business background, Azusa Street message and American perspectives. He brought together the faith healing movement inspired by Dutch Reformed minister Andrew Murray, P. Ie Roux's black and white Zion charismatic adherents affiliated with Dowie and the new U.S. Pentecostalism of Parham and Seymour. Lake's African-American influenced Pentecostalism was compatible with indigenous African worship. His emphasis on the spiritual needs of the disempowered found a receptive audience in talented black evangelists Elias Letwaba and Edward Lion. Even though acquainted with Mohandas Gandhi, Lake did not undertake a South African social gospel-type civil protest against societal injustice. In fact, Lake's participation with Afrikaner politicians like Louis Botha in fashioning a segregationist land use law was most troubling. Lake was ambivalent about racial integration. His belief in an egalitarian status for all Christians, his Populist/Progressive ethics and his enthusiastic promotion of women's rights were complicated by his advocacy, or at least tolerance, of some disparate racial treatment in his Apostolic Faith Mission and South African society at large. Lake's paternalism and notion of Westem cultural superiority conflicted with his love of all persons. Lake's otherworldly prioritization of individual spiritualism over a socioeconomic agenda usually stymied activism. His uncharacteristic use of nonviolent protest to protect faith healing formed a remarkable contrast with his reluctance to actively campaign against unequal racial treatment in Africa and America. Historiographical perspectives on Lake range from the saintly pioneer charismatic missionary to the Elmer Gantry type charlatan acting only for personal benefit. Lake was a unique personality with his flamboyant rhetoric, strong convictions and feelings of personal worth. His distinctive Jesus as healing and suffering God theology evidenced both consistency with precedent as well as creative anticipation. Shortcomings resulting from his preference to address social concerns on an individual spiritual rather than societal level, his liberties with truth and his bad business judgments resulting in litigation. Nevertheless, Lake's life demonstrated that a gifted but imperfect instrument could accomplish a meaningful ministry. , Adobe Acrobat Pro 9.5.4 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2002
- Authors: Burpeau, Kemp Pendleton
- Date: 2002
- Subjects: Lake, John G , Pentecostalism -- South Africa , Pentecostalism -- United States , Pentecostals , Christianity and politics -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2587 , http://hdl.handle.net/10962/d1006484 , Lake, John G , Pentecostalism -- South Africa , Pentecostalism -- United States , Pentecostals , Christianity and politics -- South Africa
- Description: American minister John Graham Lake (1870-1935) was a pivotal participant in an era of profound religious and political transition. Surprisingly, Lake's often provocative life had previously been largely neglected as a field of academic inquiry. In the U.S. Lake associated with key Holiness, Wesleyan and Apostolic Faith charismatics like John Alexander Dowie of the Zion City, Illinois Utopia, Charles Parham of the Topeka Revival and William Seymour of the Azusa Street Revival. Lake served as an important intermediary between Parham's often reactionary, white orientation that was unreceptive to an enthusiastic black liturgy and Seymour's expansive African-American egalitarianism expressed through exuberant spirit manifestations. Lake's South African ministry was shaped by his middle class white business background, Azusa Street message and American perspectives. He brought together the faith healing movement inspired by Dutch Reformed minister Andrew Murray, P. Ie Roux's black and white Zion charismatic adherents affiliated with Dowie and the new U.S. Pentecostalism of Parham and Seymour. Lake's African-American influenced Pentecostalism was compatible with indigenous African worship. His emphasis on the spiritual needs of the disempowered found a receptive audience in talented black evangelists Elias Letwaba and Edward Lion. Even though acquainted with Mohandas Gandhi, Lake did not undertake a South African social gospel-type civil protest against societal injustice. In fact, Lake's participation with Afrikaner politicians like Louis Botha in fashioning a segregationist land use law was most troubling. Lake was ambivalent about racial integration. His belief in an egalitarian status for all Christians, his Populist/Progressive ethics and his enthusiastic promotion of women's rights were complicated by his advocacy, or at least tolerance, of some disparate racial treatment in his Apostolic Faith Mission and South African society at large. Lake's paternalism and notion of Westem cultural superiority conflicted with his love of all persons. Lake's otherworldly prioritization of individual spiritualism over a socioeconomic agenda usually stymied activism. His uncharacteristic use of nonviolent protest to protect faith healing formed a remarkable contrast with his reluctance to actively campaign against unequal racial treatment in Africa and America. Historiographical perspectives on Lake range from the saintly pioneer charismatic missionary to the Elmer Gantry type charlatan acting only for personal benefit. Lake was a unique personality with his flamboyant rhetoric, strong convictions and feelings of personal worth. His distinctive Jesus as healing and suffering God theology evidenced both consistency with precedent as well as creative anticipation. Shortcomings resulting from his preference to address social concerns on an individual spiritual rather than societal level, his liberties with truth and his bad business judgments resulting in litigation. Nevertheless, Lake's life demonstrated that a gifted but imperfect instrument could accomplish a meaningful ministry. , Adobe Acrobat Pro 9.5.4 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2002
Cognitive justice and environmental learning in South African social movements
- Authors: Burt, Jane Caroline
- Date: 2021-04
- Subjects: Transformative learning , Water security -- South Africa , Environmental education -- South Africa , EEASA (Organization) , Civil society -- South Africa , Water justice , Cognitive justice
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/174437 , vital:42477 , http://dx.doi.org/10.21504/10962/174437
- Description: This thesis by publication is an applied study into transformative learning as an emancipatory practice for water justice. It is guided by the core research question: How can cognitively just learning be an activist practice in social movements working towards water justice? To address this question, I use the applied critical realist approach which makes use of three moments of moral reasoning which are very similar to the approach adopted in the learning intervention that is the focus of this research. These three moments are: Diagnose, Explain, Act – sometimes known as the DEA model (Bhaskar, 2008, 243; Munnik & Price, 2015). The research object is the Changing Practice course for community-based environmental and social movements. The course was developed and studied over seven years, starting from the reflexive scholarship of environmental learning in South Africa, particularly the adult learning model of working together/working away developed through the Environmental Education Association of Southern Africa in partnership with the Environmental Learning Research Centre at Rhodes University (Lotz-Sisitka & Raven, 2004). We (the facilitators/educators) ran the Changing Practice course three times (2012-2014; 2014-2016; 2016-2018), in which I generated substantive data which forms the empirical base on which this study was developed. We found the concept of cognitive justice (Visvanathan, 2005; de Sousa Santos, 2016) to be a powerful mobilizing concept with which to carry out emancipatory research and learning, in three ways. First, it brought together a group of researchers, activists and practitioners from different organizations to work on how to strengthen the role of civil society in monitoring government water policy and practice (Wilson et al., 2016). Second, within the Changing Practice course itself, it became a principle for guiding learning design and pedagogy as well as a way of engaging in dialogue with the participants around the politics of knowledge, exclusion and inclusion in knowledge production, systems of oppression and multiple knowledges (Wilson et al., 2016; Burt et al., 2018). Thirdly, the participants’ change projects (the applied projects undertaken during the ‘working away’ phase between course modules), allowed participants to draw on different knowledge systems, which they learnt to do in the ‘working together’ modules, and to address cognitive justice concerns linked to environmental justice. The change projects also challenged our learning pedagogy by raising contradictions in the course’s approach to learning that needed to be transformed in order for our pedagogy to be more cognitively just. Throughout this thesis I argue that the work of cognitive justice deepens the connections between people, institutions and structures, particularly in relation to transformative learning. Our intention was to identify and critique structures and ideologies that perpetuated oppressive relations, and then to identify and enact the work needed towards transforming these relations. This is why I often refer to cognitive justice as a solidarity and mobilizing concept, and I use the term cognitive justice praxis to mean the reflection and actions that are needed to enact cognitive just learning. The facilitators and participants of the Changing Practice course worked to remove the layered effects of oppression both in the practice of water justice and in the learning process itself. We worked, however imperfectly, with a caring, collectively-held ethic towards each other and the world. Using the DEA model I applied the critical realist dialectic to analyse contradictions and generate explanations through four articles as reflexive writing projects (See Part 2 of this thesis). I used the critical realist dialectic both to reveal contradictions, investigate how these contradictions have come to be, and to generate alternative explanations and action to absent them. Through this research I identified four essential mechanisms for cognitively just environmental learning: care work, co-learning, reflexivity and an interdisciplinary approach to learning scholarship as learning praxis. The essential elements that made the Changing Practice course so effective were the working together/working away design, the encouraging of participants to make the change project something they were passionate about, and the situating and grounding of the Changing Practice course within a social movement network. We were able to show that for academic scholarship to contribute meaningfully to cognitively just learning praxis, it needs to be collaborative and reflexive, and start from the embodied historical and contextual experience of learning as experienced and understood by participants on the course. This demanded an interdisciplinary approach to work with contradictions in learning practice, one that could take into consideration different knowledges and knowledge practices beyond professional disciplines. Both social movement communities and scholarly communities have valuable knowledge to offer each other. As argued in article one, rather than a lack of knowledge, what more often limits our emancipatory action are factors that prevent us from coming closer together. (Burt et al, 2018) This research revealed that social movement learning towards water justice is multi-level care work, the four levels being: individual psychology, our relations with others, our relations with structures such as our social movements, and our relations with the planet. When such care work attains self- reflexivity, practice-reflexivity, co-learning and collective scholarship, it is able to absent the contradictions that inhibit cognitive justice. This thesis is a record of our attempts to learn how to achieve this.
- Full Text:
- Date Issued: 2021-04
- Authors: Burt, Jane Caroline
- Date: 2021-04
- Subjects: Transformative learning , Water security -- South Africa , Environmental education -- South Africa , EEASA (Organization) , Civil society -- South Africa , Water justice , Cognitive justice
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/174437 , vital:42477 , http://dx.doi.org/10.21504/10962/174437
- Description: This thesis by publication is an applied study into transformative learning as an emancipatory practice for water justice. It is guided by the core research question: How can cognitively just learning be an activist practice in social movements working towards water justice? To address this question, I use the applied critical realist approach which makes use of three moments of moral reasoning which are very similar to the approach adopted in the learning intervention that is the focus of this research. These three moments are: Diagnose, Explain, Act – sometimes known as the DEA model (Bhaskar, 2008, 243; Munnik & Price, 2015). The research object is the Changing Practice course for community-based environmental and social movements. The course was developed and studied over seven years, starting from the reflexive scholarship of environmental learning in South Africa, particularly the adult learning model of working together/working away developed through the Environmental Education Association of Southern Africa in partnership with the Environmental Learning Research Centre at Rhodes University (Lotz-Sisitka & Raven, 2004). We (the facilitators/educators) ran the Changing Practice course three times (2012-2014; 2014-2016; 2016-2018), in which I generated substantive data which forms the empirical base on which this study was developed. We found the concept of cognitive justice (Visvanathan, 2005; de Sousa Santos, 2016) to be a powerful mobilizing concept with which to carry out emancipatory research and learning, in three ways. First, it brought together a group of researchers, activists and practitioners from different organizations to work on how to strengthen the role of civil society in monitoring government water policy and practice (Wilson et al., 2016). Second, within the Changing Practice course itself, it became a principle for guiding learning design and pedagogy as well as a way of engaging in dialogue with the participants around the politics of knowledge, exclusion and inclusion in knowledge production, systems of oppression and multiple knowledges (Wilson et al., 2016; Burt et al., 2018). Thirdly, the participants’ change projects (the applied projects undertaken during the ‘working away’ phase between course modules), allowed participants to draw on different knowledge systems, which they learnt to do in the ‘working together’ modules, and to address cognitive justice concerns linked to environmental justice. The change projects also challenged our learning pedagogy by raising contradictions in the course’s approach to learning that needed to be transformed in order for our pedagogy to be more cognitively just. Throughout this thesis I argue that the work of cognitive justice deepens the connections between people, institutions and structures, particularly in relation to transformative learning. Our intention was to identify and critique structures and ideologies that perpetuated oppressive relations, and then to identify and enact the work needed towards transforming these relations. This is why I often refer to cognitive justice as a solidarity and mobilizing concept, and I use the term cognitive justice praxis to mean the reflection and actions that are needed to enact cognitive just learning. The facilitators and participants of the Changing Practice course worked to remove the layered effects of oppression both in the practice of water justice and in the learning process itself. We worked, however imperfectly, with a caring, collectively-held ethic towards each other and the world. Using the DEA model I applied the critical realist dialectic to analyse contradictions and generate explanations through four articles as reflexive writing projects (See Part 2 of this thesis). I used the critical realist dialectic both to reveal contradictions, investigate how these contradictions have come to be, and to generate alternative explanations and action to absent them. Through this research I identified four essential mechanisms for cognitively just environmental learning: care work, co-learning, reflexivity and an interdisciplinary approach to learning scholarship as learning praxis. The essential elements that made the Changing Practice course so effective were the working together/working away design, the encouraging of participants to make the change project something they were passionate about, and the situating and grounding of the Changing Practice course within a social movement network. We were able to show that for academic scholarship to contribute meaningfully to cognitively just learning praxis, it needs to be collaborative and reflexive, and start from the embodied historical and contextual experience of learning as experienced and understood by participants on the course. This demanded an interdisciplinary approach to work with contradictions in learning practice, one that could take into consideration different knowledges and knowledge practices beyond professional disciplines. Both social movement communities and scholarly communities have valuable knowledge to offer each other. As argued in article one, rather than a lack of knowledge, what more often limits our emancipatory action are factors that prevent us from coming closer together. (Burt et al, 2018) This research revealed that social movement learning towards water justice is multi-level care work, the four levels being: individual psychology, our relations with others, our relations with structures such as our social movements, and our relations with the planet. When such care work attains self- reflexivity, practice-reflexivity, co-learning and collective scholarship, it is able to absent the contradictions that inhibit cognitive justice. This thesis is a record of our attempts to learn how to achieve this.
- Full Text:
- Date Issued: 2021-04
Genetic and bacteriophage studies on Bacteroides thetaiotaomicron and related anaerobic strains
- Authors: Burt, Sharon Joy
- Date: 1978
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:20972 , http://hdl.handle.net/10962/5753
- Description: Gram-negative obligately anaerobic bacilli were isolated from faeces on selective media. R plasmid transfer was investigated in mating experiments between 30 anaerobes and between the anaerobes and known donor and recipient E. coli strains. The transfer of R plasmids from E.coli to B.fragilis, Bacteroides spp., Fusobacterium spp. and other faecal obligate anaerobic bacteria was possible after heat treatment of the recipients at 50°C. The anaerobic exconjugants were unstable and were not able to retransfer the ampr marker. A bacteriophage, B1 , specific for the anaerobe B.thetaiotaomicron, was isolated and characterised. The properties of the phage included a variable burst size and the production of many defective phage particles without tails which were not viable. The B.thetaiotaomicron host was able to establish a phage carrier state with B1 phage. Phenol-extracted phage DNA could transfect ca2+-treated B.thetaiotaomicron cells and transfection was not limited to a particular stage in the growth cycle. An obligatory step in the transfection procedure was a 33-fold dilution in broth, allowing replication of the infected cells. Prolonged incubation of treated cells with DNA prior to dilution in broth resulted in a large decrease in phage titre. The application of this transfection system to the development of a transformation system was not successful . Conventional transformation procedures did not yield transformants, and it was not possible to transduce B.thetaiotaomicron with B1 phage. The B.thetaiotaomicron strain used was distinguished by the formation of two distinct morphological variants. Each morphological type gave rise to the other at the same frequency. Environmental conditions other than elevated temperature, had no effect on the segregation frequency. The grey colony variant was not capsulated and was sensitive to B1 phage, whereas the white colony type was encapsulated and was phage-resistant. Another feature of the B.thetaiotaomicron strain was the low incidence of mutants. A second survey of the occurrence of R plasmids in aerobic coliforms from a remote area of the Transkei and from an urban area, was undertaken. An increase in transferable antibiotic resistance was found over the last three years. It can be concluded that this was a result of the use of antibiotics among the human population, since there are no veterinary services in the area and the addition of antibiotics to animal feeds is not practised.
- Full Text:
- Date Issued: 1978
- Authors: Burt, Sharon Joy
- Date: 1978
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:20972 , http://hdl.handle.net/10962/5753
- Description: Gram-negative obligately anaerobic bacilli were isolated from faeces on selective media. R plasmid transfer was investigated in mating experiments between 30 anaerobes and between the anaerobes and known donor and recipient E. coli strains. The transfer of R plasmids from E.coli to B.fragilis, Bacteroides spp., Fusobacterium spp. and other faecal obligate anaerobic bacteria was possible after heat treatment of the recipients at 50°C. The anaerobic exconjugants were unstable and were not able to retransfer the ampr marker. A bacteriophage, B1 , specific for the anaerobe B.thetaiotaomicron, was isolated and characterised. The properties of the phage included a variable burst size and the production of many defective phage particles without tails which were not viable. The B.thetaiotaomicron host was able to establish a phage carrier state with B1 phage. Phenol-extracted phage DNA could transfect ca2+-treated B.thetaiotaomicron cells and transfection was not limited to a particular stage in the growth cycle. An obligatory step in the transfection procedure was a 33-fold dilution in broth, allowing replication of the infected cells. Prolonged incubation of treated cells with DNA prior to dilution in broth resulted in a large decrease in phage titre. The application of this transfection system to the development of a transformation system was not successful . Conventional transformation procedures did not yield transformants, and it was not possible to transduce B.thetaiotaomicron with B1 phage. The B.thetaiotaomicron strain used was distinguished by the formation of two distinct morphological variants. Each morphological type gave rise to the other at the same frequency. Environmental conditions other than elevated temperature, had no effect on the segregation frequency. The grey colony variant was not capsulated and was sensitive to B1 phage, whereas the white colony type was encapsulated and was phage-resistant. Another feature of the B.thetaiotaomicron strain was the low incidence of mutants. A second survey of the occurrence of R plasmids in aerobic coliforms from a remote area of the Transkei and from an urban area, was undertaken. An increase in transferable antibiotic resistance was found over the last three years. It can be concluded that this was a result of the use of antibiotics among the human population, since there are no veterinary services in the area and the addition of antibiotics to animal feeds is not practised.
- Full Text:
- Date Issued: 1978