A lignocellulolytic enzyme system for fruit waste degradation : commercial enzyme mixture synergy and bioreactor design
- Authors: Gama, Repson
- Date: 2014
- Subjects: Enzymes -- Biotechnology , Enzymes -- Industrial applications , Lignocellulose -- Biodegradation , Biomass energy , Biomass conversion , Biochemical engineering , Agricultural wastes as fuel
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4114 , http://hdl.handle.net/10962/d1013073
- Description: Studies into sources of alternative liquid transport fuel energy have identified agro-industrial wastes, which are lignocellulosic in nature, as a potential feedstock for biofuel production against the background of depleting nonrenewable fossil fuels. In South Africa, large quantities of apple and other fruit wastes, called pomace, are generated from fruit and juice industries. Apple pomace is a rich source of cellulose, pectin and hemicellulose, making it a potential target for utilisation as a lignocellulosic feedstock for biofuel and biorefinery chemical production. Lignocellulosic biomass is recalcitrant in nature and therefore its degradation requires the synergistic action of a number of enzymes such as cellulases, hemicellulases, pectinases and ligninases. Commercial enzyme cocktails, containing some of these enzymes, are available and can be used for apple pomace degradation. In this study, the degradation of apple pomace using commercial enzyme cocktails was investigated. The main focus was the optimisation of the release of sugar monomers that could potentially be used for biofuel and biorefinery chemical production. There is no or little information reported in literature on the enzymatic degradation of fruit waste using commercial enzyme mixtures. This study first focused on the characterisation of the substrate (apple pomace) and the commercial enzyme cocktails. Apple pomace was found to contain mainly glucose, galacturonic acid, arabinose, galactose, lignin and low amounts of xylose and fructose. Three commercial enzyme cocktails were initially selected: Biocip Membrane, Viscozyme L (from Aspergillus aculeatus) and Celluclast 1.5L (a Trichoderma reesei ATCC 26921 cellulase preparation). The selection of the enzymes was based on activities declared by the manufacturers, cost and local availability. The enzymes were screened based on their synergistic cooperation in the degradation of apple pomace and the main enzymes present in each cocktail. Viscozyme L and Celluclast 1.5L, in a 50:50 ratio, resulted in the best degree of synergy (1.6) compared to any other combination. The enzyme ratios were determined on Viscozyme L and Celluclast 1.5L based on the protein ratio. Enzyme activity was determined as glucose equivalents using the dinitrosalicylic acid (DNS) method. Sugar monomers were determined using Megazyme assay kits. There is limited information available on the enzymes present in the commercial enzyme cocktails. Therefore, the main enzymes present in Viscozyme L and Celluclast 1.5L were identified using different substrates, each targeted for a specific enzyme and activity. Characterisation of the enzyme mixtures revealed a large number of enzymes required for apple pomace degradation and these included cellulases, pectinases, xylanases, arabinases and mannanases in different proportions. Viscozyme L contained mainly pectinases and hemicellulases, while Celluclast 1.5L displayed largely cellulase and xylanase activity, hence the high degree of synergy reported. The temperature optimum was 50ºC for both enzyme mixtures and pH optima were observed at pH 5.0 and pH 3.0 for Viscozyme L and Celluclast 1.5L, respectively. At 37ºC and pH 5.0, the enzymes retained more that 90% activity after 15 days of incubation, allowing the enzymes to be used together with less energy input. The enzymes were further characterised by determining the effect of various compounds, such as alcohols, sugars, phenolic compounds and metal ions at various concentrations on the activity of the enzymes during apple pomace hydrolysis. Apart from lignin, which had almost no effect on enzyme activity, all the compounds caused inhibition of the enzymes to varying degrees. The most inhibitory compounds were some organic acids and metal ions, as well as cellobiose and xylobiose. Using the best ratio for Viscozyme L and Celluclast 1.5L (50:50) for the hydrolysis of apple pomace, it was observed that synergy was highest at the initial stages of hydrolysis and decreased over time, though the sugar concentration increased. The type of synergy for optimal apple pomace hydrolysis was found to be simultaneous. There was no synergy observed between Viscozyme L and Celluclast 1.5L with ligninases - laccase, lignin peroxidase and manganese peroxidase. Hydrolysing apple pomace with ligninases prior to addition of Viscozyme L and Celluclast 1.5L did not improve degradation of the substrate. Immobilisation of the enzyme mixtures on different supports was performed with the aim of increasing stability and enabling reuse of the enzymes. Immobilisation methods were selected based on the chemical properties of the supports, availability, cost and applicability on heterogeneous and insoluble substrate like apple pomace. These methods included crosslinked enzyme aggregates (CLEAs), immobilisation on various supports such as nylon mesh, nylon beads, sodium alginate beads, chitin and silica gel beads. The immobilisation strategies were unsuccessful, mainly due to the low percentage of immobilisation of the enzyme on the matrix and loss of activity of the immobilised enzyme. Free enzymes were therefore used for the remainder of the study. Hydrolysis conditions for apple pomace degradation were optimised using different temperatures and buffer systems in 1 L volumes mixed with compressed air. Hydrolysis at room temperature, using an unbuffered system, gave a better performance as compared to a buffered system. Reactors operated in batch mode performed better (4.2 g/L (75% yield) glucose and 16.8 g/L (75%) reducing sugar) than fed-batch reactors (3.2 g/L (66%) glucose and 14.6 g/L (72.7% yield) reducing sugar) over 100 h using Viscozyme L and Celluclast 1.5L. Supplementation of β- glucosidase activity in Viscozyme L and Celluclast 1.5L with Novozyme 188 resulted in a doubling of the amount of glucose released. The main products released from apple pomace hydrolysis were galacturonic acid, glucose and arabinose and low amounts of galactose and xylose. These products are potential raw materials for biofuel and biorefinery chemical production. An artificial neural network (ANN) model was successfully developed and used for predicting the optimum conditions for apple pomace hydrolysis using Celluclast 1.5L, Viscozyme L and Novozyme 188. Four main conditions that affect apple pomace hydrolysis were selected, namely temperature, initial pH, enzyme loading and substrate loading, which were taken as inputs. The glucose and reducing sugars released as a result of each treatment and their combinations were taken as outputs for 1–100 h. An ANN with 20, 20 and 6 neurons in the first, second and third hidden layers, respectively, was constructed. The performance and predictive ability of the ANN was good, with a R² of 0.99 and a small mean square error (MSE). New data was successfully predicted and simulated. Optimal hydrolysis conditions predicted by ANN for apple pomace hydrolysis were at 30% substrate (wet w/v) and an enzyme loading of 0.5 mg/g and 0.2 mg/mL of substrate for glucose and reducing sugar, respectively, giving sugar concentrations of 6.5 mg/mL and 28.9 mg/mL for glucose and reducing sugar, respectively. ANN showed that enzyme and substrate loadings were the most important factors for the hydrolysis of apple pomace.
- Full Text:
- Authors: Gama, Repson
- Date: 2014
- Subjects: Enzymes -- Biotechnology , Enzymes -- Industrial applications , Lignocellulose -- Biodegradation , Biomass energy , Biomass conversion , Biochemical engineering , Agricultural wastes as fuel
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4114 , http://hdl.handle.net/10962/d1013073
- Description: Studies into sources of alternative liquid transport fuel energy have identified agro-industrial wastes, which are lignocellulosic in nature, as a potential feedstock for biofuel production against the background of depleting nonrenewable fossil fuels. In South Africa, large quantities of apple and other fruit wastes, called pomace, are generated from fruit and juice industries. Apple pomace is a rich source of cellulose, pectin and hemicellulose, making it a potential target for utilisation as a lignocellulosic feedstock for biofuel and biorefinery chemical production. Lignocellulosic biomass is recalcitrant in nature and therefore its degradation requires the synergistic action of a number of enzymes such as cellulases, hemicellulases, pectinases and ligninases. Commercial enzyme cocktails, containing some of these enzymes, are available and can be used for apple pomace degradation. In this study, the degradation of apple pomace using commercial enzyme cocktails was investigated. The main focus was the optimisation of the release of sugar monomers that could potentially be used for biofuel and biorefinery chemical production. There is no or little information reported in literature on the enzymatic degradation of fruit waste using commercial enzyme mixtures. This study first focused on the characterisation of the substrate (apple pomace) and the commercial enzyme cocktails. Apple pomace was found to contain mainly glucose, galacturonic acid, arabinose, galactose, lignin and low amounts of xylose and fructose. Three commercial enzyme cocktails were initially selected: Biocip Membrane, Viscozyme L (from Aspergillus aculeatus) and Celluclast 1.5L (a Trichoderma reesei ATCC 26921 cellulase preparation). The selection of the enzymes was based on activities declared by the manufacturers, cost and local availability. The enzymes were screened based on their synergistic cooperation in the degradation of apple pomace and the main enzymes present in each cocktail. Viscozyme L and Celluclast 1.5L, in a 50:50 ratio, resulted in the best degree of synergy (1.6) compared to any other combination. The enzyme ratios were determined on Viscozyme L and Celluclast 1.5L based on the protein ratio. Enzyme activity was determined as glucose equivalents using the dinitrosalicylic acid (DNS) method. Sugar monomers were determined using Megazyme assay kits. There is limited information available on the enzymes present in the commercial enzyme cocktails. Therefore, the main enzymes present in Viscozyme L and Celluclast 1.5L were identified using different substrates, each targeted for a specific enzyme and activity. Characterisation of the enzyme mixtures revealed a large number of enzymes required for apple pomace degradation and these included cellulases, pectinases, xylanases, arabinases and mannanases in different proportions. Viscozyme L contained mainly pectinases and hemicellulases, while Celluclast 1.5L displayed largely cellulase and xylanase activity, hence the high degree of synergy reported. The temperature optimum was 50ºC for both enzyme mixtures and pH optima were observed at pH 5.0 and pH 3.0 for Viscozyme L and Celluclast 1.5L, respectively. At 37ºC and pH 5.0, the enzymes retained more that 90% activity after 15 days of incubation, allowing the enzymes to be used together with less energy input. The enzymes were further characterised by determining the effect of various compounds, such as alcohols, sugars, phenolic compounds and metal ions at various concentrations on the activity of the enzymes during apple pomace hydrolysis. Apart from lignin, which had almost no effect on enzyme activity, all the compounds caused inhibition of the enzymes to varying degrees. The most inhibitory compounds were some organic acids and metal ions, as well as cellobiose and xylobiose. Using the best ratio for Viscozyme L and Celluclast 1.5L (50:50) for the hydrolysis of apple pomace, it was observed that synergy was highest at the initial stages of hydrolysis and decreased over time, though the sugar concentration increased. The type of synergy for optimal apple pomace hydrolysis was found to be simultaneous. There was no synergy observed between Viscozyme L and Celluclast 1.5L with ligninases - laccase, lignin peroxidase and manganese peroxidase. Hydrolysing apple pomace with ligninases prior to addition of Viscozyme L and Celluclast 1.5L did not improve degradation of the substrate. Immobilisation of the enzyme mixtures on different supports was performed with the aim of increasing stability and enabling reuse of the enzymes. Immobilisation methods were selected based on the chemical properties of the supports, availability, cost and applicability on heterogeneous and insoluble substrate like apple pomace. These methods included crosslinked enzyme aggregates (CLEAs), immobilisation on various supports such as nylon mesh, nylon beads, sodium alginate beads, chitin and silica gel beads. The immobilisation strategies were unsuccessful, mainly due to the low percentage of immobilisation of the enzyme on the matrix and loss of activity of the immobilised enzyme. Free enzymes were therefore used for the remainder of the study. Hydrolysis conditions for apple pomace degradation were optimised using different temperatures and buffer systems in 1 L volumes mixed with compressed air. Hydrolysis at room temperature, using an unbuffered system, gave a better performance as compared to a buffered system. Reactors operated in batch mode performed better (4.2 g/L (75% yield) glucose and 16.8 g/L (75%) reducing sugar) than fed-batch reactors (3.2 g/L (66%) glucose and 14.6 g/L (72.7% yield) reducing sugar) over 100 h using Viscozyme L and Celluclast 1.5L. Supplementation of β- glucosidase activity in Viscozyme L and Celluclast 1.5L with Novozyme 188 resulted in a doubling of the amount of glucose released. The main products released from apple pomace hydrolysis were galacturonic acid, glucose and arabinose and low amounts of galactose and xylose. These products are potential raw materials for biofuel and biorefinery chemical production. An artificial neural network (ANN) model was successfully developed and used for predicting the optimum conditions for apple pomace hydrolysis using Celluclast 1.5L, Viscozyme L and Novozyme 188. Four main conditions that affect apple pomace hydrolysis were selected, namely temperature, initial pH, enzyme loading and substrate loading, which were taken as inputs. The glucose and reducing sugars released as a result of each treatment and their combinations were taken as outputs for 1–100 h. An ANN with 20, 20 and 6 neurons in the first, second and third hidden layers, respectively, was constructed. The performance and predictive ability of the ANN was good, with a R² of 0.99 and a small mean square error (MSE). New data was successfully predicted and simulated. Optimal hydrolysis conditions predicted by ANN for apple pomace hydrolysis were at 30% substrate (wet w/v) and an enzyme loading of 0.5 mg/g and 0.2 mg/mL of substrate for glucose and reducing sugar, respectively, giving sugar concentrations of 6.5 mg/mL and 28.9 mg/mL for glucose and reducing sugar, respectively. ANN showed that enzyme and substrate loadings were the most important factors for the hydrolysis of apple pomace.
- Full Text:
Teaching writing to Grade 5 English language learners in two Grahamstown East schools, South Africa : a case study
- Authors: Julius, Lukas Homateni
- Date: 2014
- Subjects: English language -- Study and teaching (Primary) -- South Africa -- Grahamstown English language -- Written English English language -- Composition and exercises -- Study and teaching (Primary) English language -- Ability testing Teacher effectiveness -- South Africa -- Grahamstown Teachers -- Rating of -- South Africa -- Grahamstown Written communication Second language acquisition
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1971 , http://hdl.handle.net/10962/d1011989
- Description: The majority of learners in South Africa are not native speakers of English, yet English is the dominant language of learning and teaching (LoLT). South African teachers, therefore, have the challenge of ensuring that their learners' literacy skills in English are adequately developed so as to facilitate learning in other curricular areas. This study investigated the way in which two Grade 5 teachers employed at different primary schools in the Eastern Cape province of South Africa taught writing to their English first additional language (EFAL) learners. English is the LoLT at both schools. A qualitative interpretive approach was used to identify factors that shape the ways these teachers handle the teaching of writing. The theoretical framework was informed by Borg's model of teacher cognition (2003) Shulman's conception of teacher knowledge (1987). Data collection methods consisted of interviews, classroom observations and document analysis. In-depth interviews, comprising two semi-structured interviews, two post-lesson informal conversational interviews and one stimulated recall interview were conducted with each teacher. Five of each teacher's writing lessons were observed and audio and video recorded. Samples of learners' written work were also collected. Analysis of the data reveals that the two teachers' beliefs, their experiences as learners themselves and subsequently as teachers, impacted on their pedagogy, as did other contextual factors (including the support they received from subject advisors, time management, and the number and range of learners in their classrooms). It was found that both teachers focused primarily on ensuring that their learners completed their written work so that it could be marked and graded in response to demands from their superiors, rather than on engaging deeply with the processes of writing (brainstorming, drafting, revising etc). Not only does this run counter to the writing pedagogy recommended in the Curriculum and Assessment Policy Statements (CAPS), but it also denies learners the scaffolding needed to help them develop the self-regulation skills needed to become independent writers. These findings demonstrate the need for assisting teachers to shift away from focusing only on learners' performance (testing and grading) towards a stronger emphasis on the process of writing. This would require that teachers develop a deeper understanding of the process/genre approaches to teaching writing advocated by CAPS.
- Full Text:
- Authors: Julius, Lukas Homateni
- Date: 2014
- Subjects: English language -- Study and teaching (Primary) -- South Africa -- Grahamstown English language -- Written English English language -- Composition and exercises -- Study and teaching (Primary) English language -- Ability testing Teacher effectiveness -- South Africa -- Grahamstown Teachers -- Rating of -- South Africa -- Grahamstown Written communication Second language acquisition
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1971 , http://hdl.handle.net/10962/d1011989
- Description: The majority of learners in South Africa are not native speakers of English, yet English is the dominant language of learning and teaching (LoLT). South African teachers, therefore, have the challenge of ensuring that their learners' literacy skills in English are adequately developed so as to facilitate learning in other curricular areas. This study investigated the way in which two Grade 5 teachers employed at different primary schools in the Eastern Cape province of South Africa taught writing to their English first additional language (EFAL) learners. English is the LoLT at both schools. A qualitative interpretive approach was used to identify factors that shape the ways these teachers handle the teaching of writing. The theoretical framework was informed by Borg's model of teacher cognition (2003) Shulman's conception of teacher knowledge (1987). Data collection methods consisted of interviews, classroom observations and document analysis. In-depth interviews, comprising two semi-structured interviews, two post-lesson informal conversational interviews and one stimulated recall interview were conducted with each teacher. Five of each teacher's writing lessons were observed and audio and video recorded. Samples of learners' written work were also collected. Analysis of the data reveals that the two teachers' beliefs, their experiences as learners themselves and subsequently as teachers, impacted on their pedagogy, as did other contextual factors (including the support they received from subject advisors, time management, and the number and range of learners in their classrooms). It was found that both teachers focused primarily on ensuring that their learners completed their written work so that it could be marked and graded in response to demands from their superiors, rather than on engaging deeply with the processes of writing (brainstorming, drafting, revising etc). Not only does this run counter to the writing pedagogy recommended in the Curriculum and Assessment Policy Statements (CAPS), but it also denies learners the scaffolding needed to help them develop the self-regulation skills needed to become independent writers. These findings demonstrate the need for assisting teachers to shift away from focusing only on learners' performance (testing and grading) towards a stronger emphasis on the process of writing. This would require that teachers develop a deeper understanding of the process/genre approaches to teaching writing advocated by CAPS.
- Full Text:
The microbial ecology of sulphidogenic lignocellulose degradation
- Authors: Clarke, Anna Maria
- Date: 2007
- Subjects: Microbial ecology , Lignocellulose , Sulfides , Lignin , Lignocellulose -- Biodegradation , Mines and mineral resources -- Waste disposal , Acid mine drainage
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4094 , http://hdl.handle.net/10962/d1008181
- Description: Acid mine drainage is a well known environmental pollutant, not only in South Africa, but throughout the world, and the use of microbial processes in the treatment of these wastes has been the subject of investigation over past decades. Lignocellulose packed-bed reactors have been used in passive treatment systems, and, although effective initially, they show early decline in performance while the packing material remains largely un-utilized. Little is known about this phenomenon which remains a severe constraint in the development of efficient passive mine water treatment systems. It has been proposed that the degradation pathways of the complex lignocellulose substrate may be limited in some way in these systems during the manifestation of this effect. This study has addressed the problem using a molecular microbial ecology methodology in an attempt to relate trophic functions of the microbial population to the physico-chemical data of the system. A field-scale lignocellulose packed-bed reactor located at Vryheid Coronation Colliery (Northern Kwa-Zulu Natal province, South Africa) was monitored for six years and the results showed the classic profile of performance decline related to a slowdown in sulphate reduction and alkalinity production. The reactor was decommissioned , comprehensive samples were collected along the depth profile and the microbial populations investigated by means of 16S rRNA gene methodology. The population was found to include cellulolytic Clostridia spp., CytophagaIFlavobacterlBacteroidetes, Sphingomonadaceae and as yet uncultured microorganisms related to microbiota identified in the rumen and termite gut. These are all known to be involved as primary fermenters of cellulose. Oesulphosporosinus was present as sulphate reducer. A comparison of substrata sampling and population distribution suggested that spatial and temporal gradients within the system may become established over the course of its operation. Based on these findings, a laboratory-scale reactor was constructed to simulate the performance of the packed-bed reactor under controlled experimental conditions. The laboratory-scale reactor was operated for 273 days and showed comparable performance to that in the field in both biomolecular and physicochemical data. Clearly defined trophic niches were observed. These results suggested that a sequence of events does occur in lignocellulose degradation over time. Based on the spatial and temporal column studies, a descriptive model was proposed to account for these events. It was found that fermentative organisms predominate in the inlet zone of the system using easily extractable compounds from the wood, thus providing feedstock for sulphate reduction occurring in the succeeding compartments. Production of sulphide and alkalinity appears to be involved in the enhancement of lignin degradation and this, in turn, appears to enhance access to the cellulose fraction. However, once the readily extractables are exhausted, the decline in sulphide and alkalinity production leads inexorably to a decline in the overall performance of the system as a sulphate reducing unit operation. These observations led to the proposal that with the addition of a limited amount of a readily available carbon source, such as molasses, in the initial zone of the the reactor, the ongoing generation of sulphide would be sustained and this in turn would sustain the microbial attack on the lignocellulose complex. This proposal was tested in scale-up studies and positive results indicate that the descriptive model may, to some extent, provide an account of events occurring in these systems. The work on sustaining lignocellulose degradation through the maintenance of sulphate reduction in the initial stages of the reactor flow path has led to the development of the Degrading Packed-bed Reactor concept and that, has subsequently been successfully evaluated in the field.
- Full Text:
- Authors: Clarke, Anna Maria
- Date: 2007
- Subjects: Microbial ecology , Lignocellulose , Sulfides , Lignin , Lignocellulose -- Biodegradation , Mines and mineral resources -- Waste disposal , Acid mine drainage
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4094 , http://hdl.handle.net/10962/d1008181
- Description: Acid mine drainage is a well known environmental pollutant, not only in South Africa, but throughout the world, and the use of microbial processes in the treatment of these wastes has been the subject of investigation over past decades. Lignocellulose packed-bed reactors have been used in passive treatment systems, and, although effective initially, they show early decline in performance while the packing material remains largely un-utilized. Little is known about this phenomenon which remains a severe constraint in the development of efficient passive mine water treatment systems. It has been proposed that the degradation pathways of the complex lignocellulose substrate may be limited in some way in these systems during the manifestation of this effect. This study has addressed the problem using a molecular microbial ecology methodology in an attempt to relate trophic functions of the microbial population to the physico-chemical data of the system. A field-scale lignocellulose packed-bed reactor located at Vryheid Coronation Colliery (Northern Kwa-Zulu Natal province, South Africa) was monitored for six years and the results showed the classic profile of performance decline related to a slowdown in sulphate reduction and alkalinity production. The reactor was decommissioned , comprehensive samples were collected along the depth profile and the microbial populations investigated by means of 16S rRNA gene methodology. The population was found to include cellulolytic Clostridia spp., CytophagaIFlavobacterlBacteroidetes, Sphingomonadaceae and as yet uncultured microorganisms related to microbiota identified in the rumen and termite gut. These are all known to be involved as primary fermenters of cellulose. Oesulphosporosinus was present as sulphate reducer. A comparison of substrata sampling and population distribution suggested that spatial and temporal gradients within the system may become established over the course of its operation. Based on these findings, a laboratory-scale reactor was constructed to simulate the performance of the packed-bed reactor under controlled experimental conditions. The laboratory-scale reactor was operated for 273 days and showed comparable performance to that in the field in both biomolecular and physicochemical data. Clearly defined trophic niches were observed. These results suggested that a sequence of events does occur in lignocellulose degradation over time. Based on the spatial and temporal column studies, a descriptive model was proposed to account for these events. It was found that fermentative organisms predominate in the inlet zone of the system using easily extractable compounds from the wood, thus providing feedstock for sulphate reduction occurring in the succeeding compartments. Production of sulphide and alkalinity appears to be involved in the enhancement of lignin degradation and this, in turn, appears to enhance access to the cellulose fraction. However, once the readily extractables are exhausted, the decline in sulphide and alkalinity production leads inexorably to a decline in the overall performance of the system as a sulphate reducing unit operation. These observations led to the proposal that with the addition of a limited amount of a readily available carbon source, such as molasses, in the initial zone of the the reactor, the ongoing generation of sulphide would be sustained and this in turn would sustain the microbial attack on the lignocellulose complex. This proposal was tested in scale-up studies and positive results indicate that the descriptive model may, to some extent, provide an account of events occurring in these systems. The work on sustaining lignocellulose degradation through the maintenance of sulphate reduction in the initial stages of the reactor flow path has led to the development of the Degrading Packed-bed Reactor concept and that, has subsequently been successfully evaluated in the field.
- Full Text:
Population dynamics of the raggedtooth shark (carcharias taurus) along the east coast of South Africa
- Authors: Dicken, Matthew Laurence
- Date: 2006
- Subjects: Sharks -- South Africa Shark fisheries -- South Africa Fish populations -- South Africa Sand tiger shark Fish tagging -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5310 , http://hdl.handle.net/10962/d1005155
- Description: This thesis develops the first open population model for any shark species worldwide using the Cormack-Jolly-Seber (CJS) model. In conjunction with a tagging study, five auxiliary studies were conducted to investigate stock structure, post-release mortality, tag shedding, and tag-reporting rates. The results from each of the studies were used to correct for any violations of the models assumptions to provide the first unbiased estimates of survival and abundance for the raggedtooth shark (Carcharias taurus) in South Africa. The C. taurus population exhibited complex stock structuring, by size and sex. Competitive shore anglers fished an estimated 37, 820 fishing days.year⁻¹ (95% C.I. = 28, 281 - 47, 359 days.year⁻¹) for sharks, and caught 1764 (95% C.I. = 321 – 3207) C. taurus. Although released alive, post-release mortality ranged from 3.85% for young-of-the-year sharks to 18.46% for adult sharks. Between 1984 and 2004, a total of 3471 C. taurus were tagged. In all, 302-tagged sharks (8.7%) were recaptured. Both juvenile (< 1.8 m TL) and adult sharks (> 1.8 m TL) displayed philopatric behaviour for specific parts of their ranges, including gestating and parturition areas. Significant differences were observed in the percentage of recaptures between the different tag types, tagging programs, individual taggers and capture methods used to tag sharks. The annual tag retention rate for juvenile sharks, 94.19% (95% C.I. = 80.68% - 100.00%) was significantly higher than for adult sharks, estimated at 29.00% (95% C.I. = 6.76% - 64.39%). Tag reporting rates, from fishermen varied both spatially and temporally from 0.28 (95% C.I. = 0.00 – 0.63) to 0.77 (95% C.I. = 0.56 – 0.97). Associated tag wound damage and biofouling growth indicated that B-type tags were a suitable tag type for use on C. taurus, whereas C-type tags were not. The CJS bias-adjusted estimate for juvenile survival was 0.456 (95% C.I. = 0.367 – 0.516) and for adult sharks, 0.865 (95% C.I. = 0.795 – 0.915). From 1984 to 2004 the mean bias-adjusted population size for juvenile sharks was estimated at 3506 (95% C.I. = 2433 – 4350) and for adult sharks, 5899 (95% C.I. = 7216 – 11904). Trends in abundance over the 20-year study period indicated a stable, healthy population.
- Full Text:
- Authors: Dicken, Matthew Laurence
- Date: 2006
- Subjects: Sharks -- South Africa Shark fisheries -- South Africa Fish populations -- South Africa Sand tiger shark Fish tagging -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5310 , http://hdl.handle.net/10962/d1005155
- Description: This thesis develops the first open population model for any shark species worldwide using the Cormack-Jolly-Seber (CJS) model. In conjunction with a tagging study, five auxiliary studies were conducted to investigate stock structure, post-release mortality, tag shedding, and tag-reporting rates. The results from each of the studies were used to correct for any violations of the models assumptions to provide the first unbiased estimates of survival and abundance for the raggedtooth shark (Carcharias taurus) in South Africa. The C. taurus population exhibited complex stock structuring, by size and sex. Competitive shore anglers fished an estimated 37, 820 fishing days.year⁻¹ (95% C.I. = 28, 281 - 47, 359 days.year⁻¹) for sharks, and caught 1764 (95% C.I. = 321 – 3207) C. taurus. Although released alive, post-release mortality ranged from 3.85% for young-of-the-year sharks to 18.46% for adult sharks. Between 1984 and 2004, a total of 3471 C. taurus were tagged. In all, 302-tagged sharks (8.7%) were recaptured. Both juvenile (< 1.8 m TL) and adult sharks (> 1.8 m TL) displayed philopatric behaviour for specific parts of their ranges, including gestating and parturition areas. Significant differences were observed in the percentage of recaptures between the different tag types, tagging programs, individual taggers and capture methods used to tag sharks. The annual tag retention rate for juvenile sharks, 94.19% (95% C.I. = 80.68% - 100.00%) was significantly higher than for adult sharks, estimated at 29.00% (95% C.I. = 6.76% - 64.39%). Tag reporting rates, from fishermen varied both spatially and temporally from 0.28 (95% C.I. = 0.00 – 0.63) to 0.77 (95% C.I. = 0.56 – 0.97). Associated tag wound damage and biofouling growth indicated that B-type tags were a suitable tag type for use on C. taurus, whereas C-type tags were not. The CJS bias-adjusted estimate for juvenile survival was 0.456 (95% C.I. = 0.367 – 0.516) and for adult sharks, 0.865 (95% C.I. = 0.795 – 0.915). From 1984 to 2004 the mean bias-adjusted population size for juvenile sharks was estimated at 3506 (95% C.I. = 2433 – 4350) and for adult sharks, 5899 (95% C.I. = 7216 – 11904). Trends in abundance over the 20-year study period indicated a stable, healthy population.
- Full Text:
Re-inventing educational leadership for school and community transformation: learning from the Educational Leadership Management and Development programme of the University of Fort Hare
- Authors: Moyo, George
- Date: 2005
- Subjects: University of Fort Hare. Educational Leadership Management and Development Educational leadership -- South Africa Educational change -- South Africa School management and organization -- South Africa School improvement programs -- South Africa School principals -- South Africa Community and school -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1719 , http://hdl.handle.net/10962/d1003602
- Description: This study explores educational leadership development and social change strategies pioneered by one programme, the Educational Leadership Management and Development (ELMD) programme of the University of Fort Hare. The programme seeks to model a way of doing social and educational transformation through educational leadership development. Conceptually, the model was meant to draw together a number of education stakeholders operating at various levels of the schooling system to undergo the same programme of leadership development. The programme participants, who included district education officials, schools principals, members of school management teams, educators and members of School Governing Bodies, were to enrol as teams. They would work on learning tasks that were both academic and practical in nature, with an emphasis on experiential learning that leads to the creation of district and community networks of partners, development teams or forums and communities of practice, as well as the production and implementation of district and school development plans. Informed by this conceptual position, the study was structured by two underlying questions. First, whether the ELMD was re-inventing educational leadership beyond the traditional focus on principalship towards one that is inclusive of other education stakeholders. Second, how leadership development as a vehicle for social and educational change can be carried out. The research process was guided by a multi-paradigm perspective which drew heavily on the interpretive and critical science orientations. This led to the crafting of research methods that looked for data that would assist in an understanding of what was happening in the programme, as well as what power dynamics were at play and with what consequences for innovation. The evidence emanating from the study suggests a number of possibilities for consideration by future leadership development programme designers. First, the ELMD programme delivery design shows what can be done to draw participants from various levels of the schooling system, district, school and community and teach them educational leadership together in a mode that mobilizes them for change. Second, how social distance separating different levels of the education hierarchy and status consciousness may disappear gradually as people are brought together to work on tasks of mutual concern. Third, after a year of engagement with ELMD ideas and approach, the participants in the programme appeared to have started a journey of selftransformation towards becoming qualitatively different people who saw themselves as teams capable of tackling education and social problems in their schools and communities. These participants had begun to forge working networks, but the extent to which these could be characterized as knowledge ecosystems and communities of practice remains a question to explore. Fourth, that the current higher education accreditation policies and practices do not accommodate innovative learning approaches of the kind that the ELMD is developing. In this regard, the ELMD experienced difficulties in coming up with an assessment policy and practices which meet the academic as well as the practical developmental concerns of the programme. Fifth, programme instrumentalities and mandates that are put in place do not, in themselves, bring about change. The actual change comes about through the actions of human leadership capable of navigating between structural enablers and constraints.
- Full Text:
- Authors: Moyo, George
- Date: 2005
- Subjects: University of Fort Hare. Educational Leadership Management and Development Educational leadership -- South Africa Educational change -- South Africa School management and organization -- South Africa School improvement programs -- South Africa School principals -- South Africa Community and school -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1719 , http://hdl.handle.net/10962/d1003602
- Description: This study explores educational leadership development and social change strategies pioneered by one programme, the Educational Leadership Management and Development (ELMD) programme of the University of Fort Hare. The programme seeks to model a way of doing social and educational transformation through educational leadership development. Conceptually, the model was meant to draw together a number of education stakeholders operating at various levels of the schooling system to undergo the same programme of leadership development. The programme participants, who included district education officials, schools principals, members of school management teams, educators and members of School Governing Bodies, were to enrol as teams. They would work on learning tasks that were both academic and practical in nature, with an emphasis on experiential learning that leads to the creation of district and community networks of partners, development teams or forums and communities of practice, as well as the production and implementation of district and school development plans. Informed by this conceptual position, the study was structured by two underlying questions. First, whether the ELMD was re-inventing educational leadership beyond the traditional focus on principalship towards one that is inclusive of other education stakeholders. Second, how leadership development as a vehicle for social and educational change can be carried out. The research process was guided by a multi-paradigm perspective which drew heavily on the interpretive and critical science orientations. This led to the crafting of research methods that looked for data that would assist in an understanding of what was happening in the programme, as well as what power dynamics were at play and with what consequences for innovation. The evidence emanating from the study suggests a number of possibilities for consideration by future leadership development programme designers. First, the ELMD programme delivery design shows what can be done to draw participants from various levels of the schooling system, district, school and community and teach them educational leadership together in a mode that mobilizes them for change. Second, how social distance separating different levels of the education hierarchy and status consciousness may disappear gradually as people are brought together to work on tasks of mutual concern. Third, after a year of engagement with ELMD ideas and approach, the participants in the programme appeared to have started a journey of selftransformation towards becoming qualitatively different people who saw themselves as teams capable of tackling education and social problems in their schools and communities. These participants had begun to forge working networks, but the extent to which these could be characterized as knowledge ecosystems and communities of practice remains a question to explore. Fourth, that the current higher education accreditation policies and practices do not accommodate innovative learning approaches of the kind that the ELMD is developing. In this regard, the ELMD experienced difficulties in coming up with an assessment policy and practices which meet the academic as well as the practical developmental concerns of the programme. Fifth, programme instrumentalities and mandates that are put in place do not, in themselves, bring about change. The actual change comes about through the actions of human leadership capable of navigating between structural enablers and constraints.
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Direct experience of God in contemporary theology
- Authors: Slater, Jennifer
- Date: 1994
- Subjects: Rahner, Karl, 1904-1984 -- Criticism and interpretation , Merton, Thomas, 1915-1968 -- Criticism and interpretation , Kelsey, Morton T. -- Criticism and interpretation , Fox, Matthew, -- 1940- -- Criticism and interpretation , Gutiérrez, Gustavo, 1928- -- Criticism and interpretation , God -- Knowableness , Experience (Religion) , God -- History of doctrines -- 20th century
- Language: English
- Type: Thesis , Masters , MTh
- Identifier: vital:1303 , http://hdl.handle.net/10962/d1016265
- Description: 'Direct experience of God' is a term frequently used by theologians without adequate clarification regarding its meaning. The understanding thereof has become increasingly complicated by the process of secularization. In the 1960's, it was repeatedly asserted that modern people could not have direct experiences of God, albeit that one could still live by faith and by commitment to the way of Jesus in a world in which, it was asserted, "God is dead". This claim, although long predominant, has been challenged by the upsurge of interest in mysticism, both Eastern and Western, and the burgeoning of Pentecostalism and the Charismatic movement, in which circles direct experience of God was frequently claimed. If direct experience of God is something natural to humanity, interpretation of it will vary in exactly the same way as interpretation of all other human experiences. This could be a possible reason for it being so very poorly integrated into everyday life, resulting in the loss of meaning and value.
- Full Text:
- Authors: Slater, Jennifer
- Date: 1994
- Subjects: Rahner, Karl, 1904-1984 -- Criticism and interpretation , Merton, Thomas, 1915-1968 -- Criticism and interpretation , Kelsey, Morton T. -- Criticism and interpretation , Fox, Matthew, -- 1940- -- Criticism and interpretation , Gutiérrez, Gustavo, 1928- -- Criticism and interpretation , God -- Knowableness , Experience (Religion) , God -- History of doctrines -- 20th century
- Language: English
- Type: Thesis , Masters , MTh
- Identifier: vital:1303 , http://hdl.handle.net/10962/d1016265
- Description: 'Direct experience of God' is a term frequently used by theologians without adequate clarification regarding its meaning. The understanding thereof has become increasingly complicated by the process of secularization. In the 1960's, it was repeatedly asserted that modern people could not have direct experiences of God, albeit that one could still live by faith and by commitment to the way of Jesus in a world in which, it was asserted, "God is dead". This claim, although long predominant, has been challenged by the upsurge of interest in mysticism, both Eastern and Western, and the burgeoning of Pentecostalism and the Charismatic movement, in which circles direct experience of God was frequently claimed. If direct experience of God is something natural to humanity, interpretation of it will vary in exactly the same way as interpretation of all other human experiences. This could be a possible reason for it being so very poorly integrated into everyday life, resulting in the loss of meaning and value.
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The Eucharist and history
- Paterson, Torquil John Macleod
- Authors: Paterson, Torquil John Macleod
- Date: 1990
- Subjects: Lord's Supper , History -- Religious aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1311 , http://hdl.handle.net/10962/d1018262
- Description: The thesis delineates an existential view of history, in which the eternal is defined as the ground of authentic human life which underlies true historical action. The historical is the manifestation of the eternal in the unique moment, and redefines the ahistorical conditions of human life. The ahistorical is the social and ideological conditioning of all human knowledge, usually presented in terms of various kinds of myth and ritual . The ahistorical contains both good and bad elements, but always has the tendency to become oppressive and is therefore constantly in conflict with the historical. The life of Jesus is described as the perfect expression of the eternal in true historical action, by which he came into conflict with the ahistorical of his society, as expressed in his death. By his resurrection, his life breaks the limitations of time and becomes transformative enabling all subsequent historical action. The eucharist is described as engaging with each of these dimensions of our existence. By being itself a ritual action containing a myth, the eucharist has an ahistorical form and therefore easily engages with the ahistorical dimensions of society. However, without a constant dialogue with the historical, the eucharist, as an ahistorical medium, can become allied to the dominant forces of society and become a means of oppression. The eucharist has at its centre the remembrance of the historical action of Jesus. True historical action in the present will result from a proper hermeneutic of the gospels. The eucharistic anamnesis must be regarded as part of the wider search for a relevant contemporary christology. The eucharist remembers the Last Supper, which is a parable of the whole life of Jesus and a prelude to his death and is a sacrifice in that it has a sacrificial form, and leads to our historical action, which will usually take the form of a conflict with the ahistorical and have sacrificial dimensions. The eternal only becomes present in our historical action, but the eucharist, by uniting us with the transforming power of the death and resurrection of Jesus, is a powerful aid to such action. The eucharist also provides the opportunity for resonances between Jesus and the ground of our being, thus enabling deep shifts of attitude and consciousness. Three fundamental prerequisites for human life are isolated and related to the eucharist: belonging, nurturing and giving. In order for the eucharist to ennable historical action is must hold these dimensions in tension. In its actual form it does this through the balance between the Words of Institution and the Epiclesis, which, in turn, provide the christological ground of the eucharist and relate this to the present through a particular pneumatology. The real presence is described by the thesis in a way which connects the eucharistic presence with the historical Jesus and leads to our historical action. Finally, some consequences of the thesis for Eucharistic practice are suggested. The relationship between the ahistorical form of the eucharist and the anamnesis is important. In this way the eucharist objectifies the ahistorical, reflects on this in terms of the historical action of Jesus, and reforms the ahistorical by modelling a response. This should lead to a more authentic expression of the eternal in the contemporary world
- Full Text:
- Authors: Paterson, Torquil John Macleod
- Date: 1990
- Subjects: Lord's Supper , History -- Religious aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1311 , http://hdl.handle.net/10962/d1018262
- Description: The thesis delineates an existential view of history, in which the eternal is defined as the ground of authentic human life which underlies true historical action. The historical is the manifestation of the eternal in the unique moment, and redefines the ahistorical conditions of human life. The ahistorical is the social and ideological conditioning of all human knowledge, usually presented in terms of various kinds of myth and ritual . The ahistorical contains both good and bad elements, but always has the tendency to become oppressive and is therefore constantly in conflict with the historical. The life of Jesus is described as the perfect expression of the eternal in true historical action, by which he came into conflict with the ahistorical of his society, as expressed in his death. By his resurrection, his life breaks the limitations of time and becomes transformative enabling all subsequent historical action. The eucharist is described as engaging with each of these dimensions of our existence. By being itself a ritual action containing a myth, the eucharist has an ahistorical form and therefore easily engages with the ahistorical dimensions of society. However, without a constant dialogue with the historical, the eucharist, as an ahistorical medium, can become allied to the dominant forces of society and become a means of oppression. The eucharist has at its centre the remembrance of the historical action of Jesus. True historical action in the present will result from a proper hermeneutic of the gospels. The eucharistic anamnesis must be regarded as part of the wider search for a relevant contemporary christology. The eucharist remembers the Last Supper, which is a parable of the whole life of Jesus and a prelude to his death and is a sacrifice in that it has a sacrificial form, and leads to our historical action, which will usually take the form of a conflict with the ahistorical and have sacrificial dimensions. The eternal only becomes present in our historical action, but the eucharist, by uniting us with the transforming power of the death and resurrection of Jesus, is a powerful aid to such action. The eucharist also provides the opportunity for resonances between Jesus and the ground of our being, thus enabling deep shifts of attitude and consciousness. Three fundamental prerequisites for human life are isolated and related to the eucharist: belonging, nurturing and giving. In order for the eucharist to ennable historical action is must hold these dimensions in tension. In its actual form it does this through the balance between the Words of Institution and the Epiclesis, which, in turn, provide the christological ground of the eucharist and relate this to the present through a particular pneumatology. The real presence is described by the thesis in a way which connects the eucharistic presence with the historical Jesus and leads to our historical action. Finally, some consequences of the thesis for Eucharistic practice are suggested. The relationship between the ahistorical form of the eucharist and the anamnesis is important. In this way the eucharist objectifies the ahistorical, reflects on this in terms of the historical action of Jesus, and reforms the ahistorical by modelling a response. This should lead to a more authentic expression of the eternal in the contemporary world
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Die begrip verganklikheid as komplekse kode in enkele werke van Hennie Aucamp
- Authors: Garbers, Marius Wolhuter
- Date: 1989
- Subjects: Aucamp, Hennie -- Criticism and interpretation
- Language: Afrikaans
- Type: text , Thesis , Masters , MA
- Identifier: vital:3567 , http://hdl.handle.net/10962/d1002090
- Description: Mortality has always been a popular theme in literature. By means of a semiological and narratological approach, it has been endeavoured in this study to prove that transience comprises a complex code constituted by a whole series of codes. In each of the chosen volumes one specific short story is analysed and all the codes related to transience are defined and described. Then these codes are discussed within the context of the volume as a whole. The following codes have been identified and analysed: death and death related codes, decay, distress, frustration, emptiness, loneliness observe, look and see, reproduction, the code of ageing, youth/ageing, lost love, time. The following texts of Aucamp have been used as the object of study: Die Hartseerwals, Spitsuur and 'n Bruidsbed vir Tant Nonnie. The reason these texts were selected, is twofold: They represent the early works of the author. The continuity is essential for making meaningful deductions. The final conclusions are: Man's bond with an environment which is characterised by continual change, influences his existence and makes his life a tentative experience. Transience involves more than merely ageing, obsolescence and death. Transience is a complex experience, related to the physical and mental in man. Besides ageing, sexuality contributes to man's downfall. Loneliness, isolation and frustration determine his actions and stress his experience of transience. The result is a painful experience of life.
- Full Text:
- Authors: Garbers, Marius Wolhuter
- Date: 1989
- Subjects: Aucamp, Hennie -- Criticism and interpretation
- Language: Afrikaans
- Type: text , Thesis , Masters , MA
- Identifier: vital:3567 , http://hdl.handle.net/10962/d1002090
- Description: Mortality has always been a popular theme in literature. By means of a semiological and narratological approach, it has been endeavoured in this study to prove that transience comprises a complex code constituted by a whole series of codes. In each of the chosen volumes one specific short story is analysed and all the codes related to transience are defined and described. Then these codes are discussed within the context of the volume as a whole. The following codes have been identified and analysed: death and death related codes, decay, distress, frustration, emptiness, loneliness observe, look and see, reproduction, the code of ageing, youth/ageing, lost love, time. The following texts of Aucamp have been used as the object of study: Die Hartseerwals, Spitsuur and 'n Bruidsbed vir Tant Nonnie. The reason these texts were selected, is twofold: They represent the early works of the author. The continuity is essential for making meaningful deductions. The final conclusions are: Man's bond with an environment which is characterised by continual change, influences his existence and makes his life a tentative experience. Transience involves more than merely ageing, obsolescence and death. Transience is a complex experience, related to the physical and mental in man. Besides ageing, sexuality contributes to man's downfall. Loneliness, isolation and frustration determine his actions and stress his experience of transience. The result is a painful experience of life.
- Full Text:
A hydrogeological assessment of the Uitenhage-Coega artesian system
- Authors: Venables, Anthony John
- Date: 1985
- Subjects: Hydrogeology -- South Africa Aquifers -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4808 , http://hdl.handle.net/10962/d1003815
- Description: The Uitenhage artesian aquifer north-west of Port Elizabeth in South Africa, is one of the few artesian groundwater systems in Southern Africa. The Uitenhage - Coega, and Kruis River areas, are the most important portions of the Uitenhage Artesian System in terms of water abstraction and water use. This study concentrates on the Uitenhage - Coega area and in particular, on the Coega Ridge where the Table Mountain Sandstone (TNS) aquifer occurs at relatively shallow depths. The investigation is aimed at assessing the geological, hydrogeological and hydrochemical characteristics of the HIS and any other aquifers present, with the object of providing quantitative data for use in future decisions on the water resource management of the area. In order to achieve these objectives, field work, involving a hydrocensus, geological mapping, geophysical exploration, drilling, aquifer testing and hydrochemical sampling was carried out. Analysis of these data provided information on the extent of the aquifers, their hydrogeological characteristics and the chemical nature of the various groundwater types.
- Full Text:
- Authors: Venables, Anthony John
- Date: 1985
- Subjects: Hydrogeology -- South Africa Aquifers -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4808 , http://hdl.handle.net/10962/d1003815
- Description: The Uitenhage artesian aquifer north-west of Port Elizabeth in South Africa, is one of the few artesian groundwater systems in Southern Africa. The Uitenhage - Coega, and Kruis River areas, are the most important portions of the Uitenhage Artesian System in terms of water abstraction and water use. This study concentrates on the Uitenhage - Coega area and in particular, on the Coega Ridge where the Table Mountain Sandstone (TNS) aquifer occurs at relatively shallow depths. The investigation is aimed at assessing the geological, hydrogeological and hydrochemical characteristics of the HIS and any other aquifers present, with the object of providing quantitative data for use in future decisions on the water resource management of the area. In order to achieve these objectives, field work, involving a hydrocensus, geological mapping, geophysical exploration, drilling, aquifer testing and hydrochemical sampling was carried out. Analysis of these data provided information on the extent of the aquifers, their hydrogeological characteristics and the chemical nature of the various groundwater types.
- Full Text:
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