The impact of forest degradation on carbon stocks of forests in the Matiwane area of the Transkei, South Africa
- Authors: Mangwale, Kagiso
- Date: 2011
- Subjects: Forest degradation -- Control -- South Africa -- Transkei , Forest ecology -- South Africa -- Transkei , Carbon sequestration -- South Africa -- Transkei , Forest conservation -- South Africa -- Transkei
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4781 , http://hdl.handle.net/10962/d1012799 , Forest degradation -- Control -- South Africa -- Transkei , Forest ecology -- South Africa -- Transkei , Carbon sequestration -- South Africa -- Transkei , Forest conservation -- South Africa -- Transkei
- Description: This study focused on assessing the condition and creating a carbon inventory of forests in the Matiwane area of the Transkei. This entailed the use of aerial photography in tracing forest cover change from 1942 to 2007 coupled with ground-truthing to assess whether the forests have in any way endured degradation over the years with a potential reduction in carbon stocks as a result. This study revealed both the loss and gain of biomass in the area with a general trend of forests being continuously converted to agricultural fields resulting in reduced forest area, stem density, tree density and carbon loss in different pools of the forests, reflecting that these forests are degraded. The conversion has resulted in the reduction in the number of species from a mean of 11±0.57 species/200m² in intact forests to 1±0.23species/200m² plot in degraded forests. It was also revealed that approximately 5.2 % (791 hectares) of 15 352 hectares of forest area was lost as a result of the conversion of forest land to agricultural fields from 1942 to 2007 with 99 % of the clearing occurring in the last 33 years (1974-2007) and of which 60 % ( 4 77 hectares) occurred from 1995 to 2007, indicating that forest degradation in these forests is on the increase. The assessment also revealed some areas that were nonforest in 1942 that have accumulated woody biomass (BAA), composed mainly of Acacia sp accounting for 51.18 MgC.ha⁻¹ (Megagrams of carbon per hectare) and total carbon stocks of 0.02 TgC (Teragrams of carbon). The degradation of these forests induced a reduction in carbon stocks from 311.68±23.69 MgC.ha⁻¹ (to a soil depth 0-50 cm) in intact forest to 73.46±12.34 MgC.ha⁻¹ in degraded forests. The total carbon stocks in the degraded forests were approximated at 0.06 TgC and the BAA areas 0.02 TgC with 4.7 TgC in intact forests. The degradation of these forests has resulted in the net carbon loss of 0.19 TgC between 1942 and 2007 but 4.76 TgC is still locked in these forests. The large difference in carbon stocks between intact and degraded forests indicated the need to reduce the degradation of these forests to prevent further carbon loss and reduction of the carbon sequestration potential of these forests.
- Full Text:
- Date Issued: 2011
- Authors: Mangwale, Kagiso
- Date: 2011
- Subjects: Forest degradation -- Control -- South Africa -- Transkei , Forest ecology -- South Africa -- Transkei , Carbon sequestration -- South Africa -- Transkei , Forest conservation -- South Africa -- Transkei
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4781 , http://hdl.handle.net/10962/d1012799 , Forest degradation -- Control -- South Africa -- Transkei , Forest ecology -- South Africa -- Transkei , Carbon sequestration -- South Africa -- Transkei , Forest conservation -- South Africa -- Transkei
- Description: This study focused on assessing the condition and creating a carbon inventory of forests in the Matiwane area of the Transkei. This entailed the use of aerial photography in tracing forest cover change from 1942 to 2007 coupled with ground-truthing to assess whether the forests have in any way endured degradation over the years with a potential reduction in carbon stocks as a result. This study revealed both the loss and gain of biomass in the area with a general trend of forests being continuously converted to agricultural fields resulting in reduced forest area, stem density, tree density and carbon loss in different pools of the forests, reflecting that these forests are degraded. The conversion has resulted in the reduction in the number of species from a mean of 11±0.57 species/200m² in intact forests to 1±0.23species/200m² plot in degraded forests. It was also revealed that approximately 5.2 % (791 hectares) of 15 352 hectares of forest area was lost as a result of the conversion of forest land to agricultural fields from 1942 to 2007 with 99 % of the clearing occurring in the last 33 years (1974-2007) and of which 60 % ( 4 77 hectares) occurred from 1995 to 2007, indicating that forest degradation in these forests is on the increase. The assessment also revealed some areas that were nonforest in 1942 that have accumulated woody biomass (BAA), composed mainly of Acacia sp accounting for 51.18 MgC.ha⁻¹ (Megagrams of carbon per hectare) and total carbon stocks of 0.02 TgC (Teragrams of carbon). The degradation of these forests induced a reduction in carbon stocks from 311.68±23.69 MgC.ha⁻¹ (to a soil depth 0-50 cm) in intact forest to 73.46±12.34 MgC.ha⁻¹ in degraded forests. The total carbon stocks in the degraded forests were approximated at 0.06 TgC and the BAA areas 0.02 TgC with 4.7 TgC in intact forests. The degradation of these forests has resulted in the net carbon loss of 0.19 TgC between 1942 and 2007 but 4.76 TgC is still locked in these forests. The large difference in carbon stocks between intact and degraded forests indicated the need to reduce the degradation of these forests to prevent further carbon loss and reduction of the carbon sequestration potential of these forests.
- Full Text:
- Date Issued: 2011
The implementation and evaluation of a service-learning component in a second year undergraduate organic chemistry course
- Authors: Abel, Sarah Ruth
- Date: 2011 , 2010-10-03
- Subjects: Chemistry, Organic -- Study and teaching (Higher) -- South Africa , Action research in education -- South Africa , Experiential learning -- South Africa , Service learning -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4393 , http://hdl.handle.net/10962/d1006008 , Chemistry, Organic -- Study and teaching (Higher) -- South Africa , Action research in education -- South Africa , Experiential learning -- South Africa , Service learning -- South Africa
- Description: The project describes the action research implementation, and evaluation of learning, of a service-learning component in a second year undergraduate organic chemistry course. The research aims to explore the learning that takes place in a service-learning context while utilizing an action research methodology within the critical theory paradigm. This occurs in response to the world-wide call for Higher Education to produce people with civic competencies and responsiveness to the society in which they live (Boyer 1996). Educating young Chemists to see the importance of their knowledge and their responsibilities in society is an important pedagogical step in the effort to cross boundaries and make connections between people communities (Eyler and Giles 1999). The goal of this project was to explore and categorize the learning that takes place in a service-learning context and discover how these areas of learning impact the awareness of the parties involved with regard to the discipline of chemistry as well as social issues. The project makes use of Kolb‘s (1984) Experiential Learning Theory, and Eyler and Giles‘ (1999) categories of learning in service-learning and results indicate that service-learning can be a powerful pedagogical tool to increase learning in chemistry as well as in the areas of critical thinking, personal and social development, reflection and citizenship. Students‘ perceptions of themselves, their discipline and their responsibility to society were transformed by their experience of service-learning in their undergraduate chemistry course.
- Full Text:
- Date Issued: 2011
- Authors: Abel, Sarah Ruth
- Date: 2011 , 2010-10-03
- Subjects: Chemistry, Organic -- Study and teaching (Higher) -- South Africa , Action research in education -- South Africa , Experiential learning -- South Africa , Service learning -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4393 , http://hdl.handle.net/10962/d1006008 , Chemistry, Organic -- Study and teaching (Higher) -- South Africa , Action research in education -- South Africa , Experiential learning -- South Africa , Service learning -- South Africa
- Description: The project describes the action research implementation, and evaluation of learning, of a service-learning component in a second year undergraduate organic chemistry course. The research aims to explore the learning that takes place in a service-learning context while utilizing an action research methodology within the critical theory paradigm. This occurs in response to the world-wide call for Higher Education to produce people with civic competencies and responsiveness to the society in which they live (Boyer 1996). Educating young Chemists to see the importance of their knowledge and their responsibilities in society is an important pedagogical step in the effort to cross boundaries and make connections between people communities (Eyler and Giles 1999). The goal of this project was to explore and categorize the learning that takes place in a service-learning context and discover how these areas of learning impact the awareness of the parties involved with regard to the discipline of chemistry as well as social issues. The project makes use of Kolb‘s (1984) Experiential Learning Theory, and Eyler and Giles‘ (1999) categories of learning in service-learning and results indicate that service-learning can be a powerful pedagogical tool to increase learning in chemistry as well as in the areas of critical thinking, personal and social development, reflection and citizenship. Students‘ perceptions of themselves, their discipline and their responsibility to society were transformed by their experience of service-learning in their undergraduate chemistry course.
- Full Text:
- Date Issued: 2011
The influence of fire and plantation management on Wetlands on the Tsitsikamma plateau
- Authors: Hugo, Christine Denise
- Date: 2011
- Subjects: Forest management -- South Africa -- Tsitsikama Plateau , Dragonflies -- Effect of habitat modification on -- South Africa -- Tsitsikama Plateau
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10747 , http://hdl.handle.net/10948/1464 , Forest management -- South Africa -- Tsitsikama Plateau , Dragonflies -- Effect of habitat modification on -- South Africa -- Tsitsikama Plateau
- Description: Wetlands on the extensively afforested Tsitsikamma Plateau are prone to fire and according to foresters, they behave as fire channels that under bergwind conditions rapidly carry fire into plantations. The destruction of plantations causes great economic loss and MTO would therefore prefer to afforest some smaller wetlands to limit the fire hazard. This study was carried out in the middle of a drought period and sought to determine the influence of fire, plantation management and the environment on wetlands and its component species. This study of palustrine wetlands on the Tsitsikamma Plateau identified five wetland vegetation communities, in which plant species richness was relatively low. Plant compositional structure of wetlands is influenced by wetland location, the height of the adjacent plantation and fire frequency. This study found a pronounced plant species turnover from west to east and soil coarseness increased along the same gradient. Re-sprouters dominated the wetland communities in the Tsitsikamma but a few populations of the obligate re-seeding ‘Near threatened’ Leucadendron conicum rely on fire for rejuvenation purposes. Regarding dragonflies in wetlands, abundance was found to be low, while species richness was relatively high considering the absence of surface water. The study found that fire indirectly influenced dragonfly abundance and species composition by altering vegetation structure. Dragonfly abundance and species richness was generally higher in wetlands with older vegetation (≥ 9 years). Further, most dragonflies frequenting the palustrine wetland habitats were females. Seeing that female dragonflies spend most of their time away from prime breeding habitats to escape male harassment, the study indicated these wetlands as important refuge habitats for them. Dragonfly abundance is expected to increase once the drought ends; however, the overall patterns observed are likely to remain unchanged under wetter conditions. Narrow wetlands (< 10 m) are few on the plateau and it is not advisable to sacrifice wider wetlands in the Tsitsikamma. Further, with regards to ecological processes and wetlands’ influence on the surrounding Tsitsikamma matrix, more research is needed before wetlands may be sacrificed. To deal with the fire risk the Tsitsikamma environment poses to plantations, it is strongly recommended to establish and maintain a cleared buffer area between plantations and wetlands. Further, for vegetation rejuvenation purposes, it is important to burn wetlands at irregular intervals but not more frequently than every nine years and not less frequently than every 25-30 years.
- Full Text:
- Date Issued: 2011
- Authors: Hugo, Christine Denise
- Date: 2011
- Subjects: Forest management -- South Africa -- Tsitsikama Plateau , Dragonflies -- Effect of habitat modification on -- South Africa -- Tsitsikama Plateau
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10747 , http://hdl.handle.net/10948/1464 , Forest management -- South Africa -- Tsitsikama Plateau , Dragonflies -- Effect of habitat modification on -- South Africa -- Tsitsikama Plateau
- Description: Wetlands on the extensively afforested Tsitsikamma Plateau are prone to fire and according to foresters, they behave as fire channels that under bergwind conditions rapidly carry fire into plantations. The destruction of plantations causes great economic loss and MTO would therefore prefer to afforest some smaller wetlands to limit the fire hazard. This study was carried out in the middle of a drought period and sought to determine the influence of fire, plantation management and the environment on wetlands and its component species. This study of palustrine wetlands on the Tsitsikamma Plateau identified five wetland vegetation communities, in which plant species richness was relatively low. Plant compositional structure of wetlands is influenced by wetland location, the height of the adjacent plantation and fire frequency. This study found a pronounced plant species turnover from west to east and soil coarseness increased along the same gradient. Re-sprouters dominated the wetland communities in the Tsitsikamma but a few populations of the obligate re-seeding ‘Near threatened’ Leucadendron conicum rely on fire for rejuvenation purposes. Regarding dragonflies in wetlands, abundance was found to be low, while species richness was relatively high considering the absence of surface water. The study found that fire indirectly influenced dragonfly abundance and species composition by altering vegetation structure. Dragonfly abundance and species richness was generally higher in wetlands with older vegetation (≥ 9 years). Further, most dragonflies frequenting the palustrine wetland habitats were females. Seeing that female dragonflies spend most of their time away from prime breeding habitats to escape male harassment, the study indicated these wetlands as important refuge habitats for them. Dragonfly abundance is expected to increase once the drought ends; however, the overall patterns observed are likely to remain unchanged under wetter conditions. Narrow wetlands (< 10 m) are few on the plateau and it is not advisable to sacrifice wider wetlands in the Tsitsikamma. Further, with regards to ecological processes and wetlands’ influence on the surrounding Tsitsikamma matrix, more research is needed before wetlands may be sacrificed. To deal with the fire risk the Tsitsikamma environment poses to plantations, it is strongly recommended to establish and maintain a cleared buffer area between plantations and wetlands. Further, for vegetation rejuvenation purposes, it is important to burn wetlands at irregular intervals but not more frequently than every nine years and not less frequently than every 25-30 years.
- Full Text:
- Date Issued: 2011
The medicinal chemistry of cyclo(D-Phe-2Cl-Pro) and cyclo(Phe-4F-Pro)
- Authors: Ndung'u, Susan Wanjiru
- Date: 2011
- Subjects: Peptide drugs , Cyclic peptides , Pharmaceutical chemistry , Peptides -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/7083 , vital:21223
- Description: Although peptides and proteins are considered as lead compounds for the discovery and development of new therapeutic agents, poor metabolic and physical properties have limited their optimisation as drug candidates (Adessi & Soto, 2002). Research by medicinal chemists however, generated the discovery of structural similarities between some peptides and diketopiperazines and the common occurrence of such compounds in natural products. This discovery initiated the synthesis of diketopiperazines from amino acids in an attempt to bypass the previously mentioned limitations of using peptides as drug candidates (Dinsmore & Beshore, 2002). Diketopiperazines (DKPs) are the simplest form of cyclic dipeptides, and a class of unexplored bioactive peptides that have great potential for the future. The compounds are relatively simple to synthesise and are prevalent in nature (Prasad, 1995). The DKP backbone is rigid and therefore poses conformational constraint on the compounds. This rigidity allows for simple conformational analysis of the compounds and also gives insight into the conformational requirements for interaction with the targets involved in their biological activity. The reduced conformational freedom also increases the receptor specificity and thus the compounds are proposed to have less unfavourable effects (Anteunis, 1978). The aim of the study was to synthesise compounds that would exhibit metabolic stability, receptor specificity and enhanced lipophilicity which would increase the bioavailability of the compounds. This was to be achieved by the introduction of fluorine and chlorine elements into the DKPs. The structure of the DKPs would be altered which in turn would improve the physicochemical properties and the biological activity of the compounds (Naumann, 1999). Cyclo(D-Phe-2Cl-Pro) and cyclo(Phe-4F-Pro) were synthesised using the method of Milne et al. (1992) and by boiling the linear counterparts under reflux in sec-butanol-toluene. The structures of the synthesised DKPs were elucidated using mass spectrometry, nuclear magnetic resonance spectroscopy, infrared spectroscopy and molecular modeling. Qualitative analysis and evaluation of the physicochemical properties of the DKPs were performed using high-performance liquid chromatography, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry and x-ray powder diffraction. The study aimed to determine the biological activity of cyclo(D-Phe-2Cl-Pro) and cyclo(Phe-4F-Pro) with respect to their anticancer, antimicrobial, haematological and antidiabetic effects. The anticancer results obtained indicated that the percentage inhibition produced by both DKPs were lower than those proposed by Graz et al. (2000) for proline-containing DKPs where, a greater than 50% inhibition was observed for cyclo(Phe-Pro). Antimicrobial studies revealed that both DKPs demonstrated marginal effects on Gram-positive and Gram-negative organisms but showed significant effects against C. albicans. The haematological studies revealed that cyclo(D-Phe-2Cl-Pro) at a screening concentration of 12.5 mM, significantly decreased the levels of D-dimer (P < 0.0001). The antidiabetics studies showed limited activity of the DKPs in inhibiting the activity of α-glucosidase and α-amylase enzymes.
- Full Text:
- Date Issued: 2011
- Authors: Ndung'u, Susan Wanjiru
- Date: 2011
- Subjects: Peptide drugs , Cyclic peptides , Pharmaceutical chemistry , Peptides -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/7083 , vital:21223
- Description: Although peptides and proteins are considered as lead compounds for the discovery and development of new therapeutic agents, poor metabolic and physical properties have limited their optimisation as drug candidates (Adessi & Soto, 2002). Research by medicinal chemists however, generated the discovery of structural similarities between some peptides and diketopiperazines and the common occurrence of such compounds in natural products. This discovery initiated the synthesis of diketopiperazines from amino acids in an attempt to bypass the previously mentioned limitations of using peptides as drug candidates (Dinsmore & Beshore, 2002). Diketopiperazines (DKPs) are the simplest form of cyclic dipeptides, and a class of unexplored bioactive peptides that have great potential for the future. The compounds are relatively simple to synthesise and are prevalent in nature (Prasad, 1995). The DKP backbone is rigid and therefore poses conformational constraint on the compounds. This rigidity allows for simple conformational analysis of the compounds and also gives insight into the conformational requirements for interaction with the targets involved in their biological activity. The reduced conformational freedom also increases the receptor specificity and thus the compounds are proposed to have less unfavourable effects (Anteunis, 1978). The aim of the study was to synthesise compounds that would exhibit metabolic stability, receptor specificity and enhanced lipophilicity which would increase the bioavailability of the compounds. This was to be achieved by the introduction of fluorine and chlorine elements into the DKPs. The structure of the DKPs would be altered which in turn would improve the physicochemical properties and the biological activity of the compounds (Naumann, 1999). Cyclo(D-Phe-2Cl-Pro) and cyclo(Phe-4F-Pro) were synthesised using the method of Milne et al. (1992) and by boiling the linear counterparts under reflux in sec-butanol-toluene. The structures of the synthesised DKPs were elucidated using mass spectrometry, nuclear magnetic resonance spectroscopy, infrared spectroscopy and molecular modeling. Qualitative analysis and evaluation of the physicochemical properties of the DKPs were performed using high-performance liquid chromatography, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry and x-ray powder diffraction. The study aimed to determine the biological activity of cyclo(D-Phe-2Cl-Pro) and cyclo(Phe-4F-Pro) with respect to their anticancer, antimicrobial, haematological and antidiabetic effects. The anticancer results obtained indicated that the percentage inhibition produced by both DKPs were lower than those proposed by Graz et al. (2000) for proline-containing DKPs where, a greater than 50% inhibition was observed for cyclo(Phe-Pro). Antimicrobial studies revealed that both DKPs demonstrated marginal effects on Gram-positive and Gram-negative organisms but showed significant effects against C. albicans. The haematological studies revealed that cyclo(D-Phe-2Cl-Pro) at a screening concentration of 12.5 mM, significantly decreased the levels of D-dimer (P < 0.0001). The antidiabetics studies showed limited activity of the DKPs in inhibiting the activity of α-glucosidase and α-amylase enzymes.
- Full Text:
- Date Issued: 2011
The photodecomposition of different polymorphic forms of 1,4-dihydropyridine channel blockers
- Authors: Francis, Farzaana
- Date: 2011
- Subjects: Photodegradation , Nifedipine , Nimodipine , Dihydropyridine
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10378 , http://hdl.handle.net/10948/1496 , Photodegradation , Nifedipine , Nimodipine , Dihydropyridine
- Description: 1,4-Dihydropyridines (DHPs) are a classification of compounds used as calcium channel blockers in the treatment of various conditions. These compounds readily undergo photodegradation. The degradants produced have no pharmaceutical activity and render the drugs ineffective. DHPs also exhibit polymorphism. Nifedipine and Nimodipine are two such drugs. This study aimed to monitor the photodegradation of these two drugs and to establish the effect of particle size, polymorphism and β-Cyclodextrin (β-CD) on the rate of photodegradation. Different polymorphs (namely the amorphous and stable crystalline polymorphs) of the two drugs were prepared for use in the study. Mixtures of each drug with β-CD were also prepared for photostability studies. The mixtures were prepared in a 1:1 molar ratio. The rate of photodegradation was studied with a 500 W metal halide lamp in accordance to ICH guidelines. The study employed samples on a small scale where degradation was analysed with High Performance Liquid Chromatography, and also samples on a larger scale where degradation was monitored with Powder X-ray Diffraction. The two sets of results of observing the degradation process by two analytical techniques where compared in terms of their quantification methods. The extent of photodegradation was suitably modelled and fitted using the Avrami-Erofeyev kinetic equation. Smaller particle size showed increased photodegradation for Nimodipine; the effect was insignificant for Nifedipine however. For both drugs it was found that the amorphous polymorph underwent faster photodegradation. The study showed that β-CD caused an increase in photodegradation for both drugs under these experimental conditions.
- Full Text:
- Date Issued: 2011
- Authors: Francis, Farzaana
- Date: 2011
- Subjects: Photodegradation , Nifedipine , Nimodipine , Dihydropyridine
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10378 , http://hdl.handle.net/10948/1496 , Photodegradation , Nifedipine , Nimodipine , Dihydropyridine
- Description: 1,4-Dihydropyridines (DHPs) are a classification of compounds used as calcium channel blockers in the treatment of various conditions. These compounds readily undergo photodegradation. The degradants produced have no pharmaceutical activity and render the drugs ineffective. DHPs also exhibit polymorphism. Nifedipine and Nimodipine are two such drugs. This study aimed to monitor the photodegradation of these two drugs and to establish the effect of particle size, polymorphism and β-Cyclodextrin (β-CD) on the rate of photodegradation. Different polymorphs (namely the amorphous and stable crystalline polymorphs) of the two drugs were prepared for use in the study. Mixtures of each drug with β-CD were also prepared for photostability studies. The mixtures were prepared in a 1:1 molar ratio. The rate of photodegradation was studied with a 500 W metal halide lamp in accordance to ICH guidelines. The study employed samples on a small scale where degradation was analysed with High Performance Liquid Chromatography, and also samples on a larger scale where degradation was monitored with Powder X-ray Diffraction. The two sets of results of observing the degradation process by two analytical techniques where compared in terms of their quantification methods. The extent of photodegradation was suitably modelled and fitted using the Avrami-Erofeyev kinetic equation. Smaller particle size showed increased photodegradation for Nimodipine; the effect was insignificant for Nifedipine however. For both drugs it was found that the amorphous polymorph underwent faster photodegradation. The study showed that β-CD caused an increase in photodegradation for both drugs under these experimental conditions.
- Full Text:
- Date Issued: 2011
The photophysical properties of low symmetry phthalocyanines in conjunction with quantum dots
- Authors: D'Souza, Sarah
- Date: 2011
- Subjects: Phthalocyanines , Photochemistry , Zinc , Quantum dots , Spectrum analysis , Nanoparticles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4331 , http://hdl.handle.net/10962/d1004992 , Phthalocyanines , Photochemistry , Zinc , Quantum dots , Spectrum analysis , Nanoparticles
- Description: he synthesis, extensive spectroscopic characterization and photophysical studies of low symmetry zinc phthalocyanine have been conducted. Comparisons have been made taking into consideration the influence of the solvent properties as well as substituent type and position. Photosensitizing properties of the zinc phthalocyanine derivatives in the presence of thiol capped CdTe quantum dots (QDs) were compared. The QDs were used as energy transfer donors and to facilitate with energy transfer through Förster resonance energy transfer (FRET) from the QDs to the MPcs. The linkage of unsymmetrically substituted 4-monoaminophenoxy zinc phthalocyanine (ZnAPPc) to CdTe quantum dots capped with mercaptopropionic acid (MPA), L-cysteine (L-cys) or thioglycolic acid (TGA) has been achieved using the coupling agents ethyl-N3 dimethylaminopropyl)carbodiimide (EDC) and N-hydroxy succinimide (NHS), which facilitate formation of an amide bond to form the QD-ZnAPPc-linked complex. The formation of the amide bond was confirmed using UV-Vis, Raman and IR spectroscopies, as well as AFM (atomic force microscopy). Förster resonance energy transfer (FRET) resulted in stimulated emission of ZnAPPc in both the linked (QDZnAPPc-linked) and mixed (QD:ZnAPPc-mixed) conjugates for MPA only. The linked L-cys and TGA complexes (QD-ZnAPPc-linked) gave the largest FRET efficiencies hence showing the advantages of covalent linking. Fluorescence quantum yields of QDs were decreased in QD:ZnAPPc-mixed and QD:ZnAPPc-linked. High triplet state quantum yields were obtained for the linked QD-phthalocyanine derivatives (ZnAPPc)and monoaminozinc phthalocyanine (ZnAPc) compared to when ZnAPPc and ZnAPc were mixed with MPA QDs without a chemical bond.
- Full Text:
- Date Issued: 2011
- Authors: D'Souza, Sarah
- Date: 2011
- Subjects: Phthalocyanines , Photochemistry , Zinc , Quantum dots , Spectrum analysis , Nanoparticles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4331 , http://hdl.handle.net/10962/d1004992 , Phthalocyanines , Photochemistry , Zinc , Quantum dots , Spectrum analysis , Nanoparticles
- Description: he synthesis, extensive spectroscopic characterization and photophysical studies of low symmetry zinc phthalocyanine have been conducted. Comparisons have been made taking into consideration the influence of the solvent properties as well as substituent type and position. Photosensitizing properties of the zinc phthalocyanine derivatives in the presence of thiol capped CdTe quantum dots (QDs) were compared. The QDs were used as energy transfer donors and to facilitate with energy transfer through Förster resonance energy transfer (FRET) from the QDs to the MPcs. The linkage of unsymmetrically substituted 4-monoaminophenoxy zinc phthalocyanine (ZnAPPc) to CdTe quantum dots capped with mercaptopropionic acid (MPA), L-cysteine (L-cys) or thioglycolic acid (TGA) has been achieved using the coupling agents ethyl-N3 dimethylaminopropyl)carbodiimide (EDC) and N-hydroxy succinimide (NHS), which facilitate formation of an amide bond to form the QD-ZnAPPc-linked complex. The formation of the amide bond was confirmed using UV-Vis, Raman and IR spectroscopies, as well as AFM (atomic force microscopy). Förster resonance energy transfer (FRET) resulted in stimulated emission of ZnAPPc in both the linked (QDZnAPPc-linked) and mixed (QD:ZnAPPc-mixed) conjugates for MPA only. The linked L-cys and TGA complexes (QD-ZnAPPc-linked) gave the largest FRET efficiencies hence showing the advantages of covalent linking. Fluorescence quantum yields of QDs were decreased in QD:ZnAPPc-mixed and QD:ZnAPPc-linked. High triplet state quantum yields were obtained for the linked QD-phthalocyanine derivatives (ZnAPPc)and monoaminozinc phthalocyanine (ZnAPc) compared to when ZnAPPc and ZnAPc were mixed with MPA QDs without a chemical bond.
- Full Text:
- Date Issued: 2011
The response of microalgal biomass and community composition to environmental factors in the Sundays Estuary
- Authors: Kotsedi, Daisy
- Date: 2011
- Subjects: Algal blooms -- South Africa -- Sundays River Estuary
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10609 , http://hdl.handle.net/10948/1434 , Algal blooms -- South Africa -- Sundays River Estuary
- Description: The Sundays Estuary is permanently open to the sea and has been described as channel-like along its entire length with a narrow intertidal area (mostly less than 5 - 6 m in width). The estuary experiences regular freshwater inflow with large supplies of nutrients, derived from the Orange River transfer scheme and agricultural return flow. In particular, nitrate concentrations are high as a result of fertilisers used in the Sundays River catchment area. The objectives of this study were to measure microalgal biomass and community composition and relate to flow, water quality and other environmental variables. Surveys in August 2006, March 2007, February, June and August 2008 showed that salinity less than 10 percent mostly occurred from 12.5 km from the mouth and this was also where the highest water column chlorophyll a (>20 μg l-1) was found. Different groups of microalgae formed phytoplankton blooms for the different sampling sessions, which were correlated with high chlorophyll a. These included blooms of green algae (August 2006), flagellates (March 2007), dinoflagellates (June 2008) and diatom species (February and August 2008). The dominant diatom (Cyclotella atomus) indicated nutrient-rich conditions. Green algae and diatoms were associated with low salinity water in the upper reaches of the estuary. Flagellates were dominant throughout the estuary particularly when nutrients were low, whereas the dinoflagellate bloom in June 2008 was correlated with high ammonium and pH. Maximum benthic chlorophyll a was found at 12.5 km from the mouth in February, June and August 2008 and was correlated with high sediment organic and moisture content. Benthic diatoms were associated with high temperature whereas some species in June 2008 were associated with high ammonium concentrations. The middle reaches of the estuary characterise a zone of deposition rather than suspension which would favour benthic diatom colonization. Phytoplankton cells settling out on the sediments may account for the high benthic chlorophyll a because maximum water column chlorophyll a was also found in the REI zone (where salinity is less than 10 percent and where high biological activity occurs) in the Sundays Estuary. The estuary was sampled over five consecutive weeks from March to April 2009 to identify environmental factors that support different microalgal bloom species. Phytoplankton blooms, defined as chlorophyll a greater than 20 μg l-1, were found during Weeks 1, 4 and 5 from the middle to the upper reaches of the estuary. Diatom species (Cylindrotheca closterium, Cyclotella atomus and Cyclostephanus dubius) occurred in bloom concentrations during these weeks. These diatom species are cosmopolitan and indicate brackish nutrient-rich water. Flagellates were the dominant group in Weeks 2 to 4, but positive correlations with chlorophyll a were found during Weeks 1 and 2. During the first week of this study the conditions were warm and calm (measured as temperature and wind speed) and there was a well developed bloom (38 μg l-1). There was a strong cold front from 17 to 19 March, which mixed the water column resulting in the decrease of the chlorophyll a levels (<20 μg l-1) and the bloom collapsed during Weeks 2 and 3. However, in Weeks 4 and 5 conditions were again calm and warmer, which appeared to stimulate the phytoplankton bloom. Nanoplankton (2.7 - 20 μm) was dominant during each week sampled and contributed a considerable amount (55 - 79 percent) to the phytoplankton biomass. Once again subtidal benthic chlorophyll a and water column chlorophyll a were highest 12.5 km from the mouth. Deposition of phytoplankton cells from the water column was evident in the benthic samples. The study showed that the Sundays Estuary is eutrophic and characterised by microalgal blooms consisting of different phytoplankton groups.
- Full Text:
- Date Issued: 2011
- Authors: Kotsedi, Daisy
- Date: 2011
- Subjects: Algal blooms -- South Africa -- Sundays River Estuary
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10609 , http://hdl.handle.net/10948/1434 , Algal blooms -- South Africa -- Sundays River Estuary
- Description: The Sundays Estuary is permanently open to the sea and has been described as channel-like along its entire length with a narrow intertidal area (mostly less than 5 - 6 m in width). The estuary experiences regular freshwater inflow with large supplies of nutrients, derived from the Orange River transfer scheme and agricultural return flow. In particular, nitrate concentrations are high as a result of fertilisers used in the Sundays River catchment area. The objectives of this study were to measure microalgal biomass and community composition and relate to flow, water quality and other environmental variables. Surveys in August 2006, March 2007, February, June and August 2008 showed that salinity less than 10 percent mostly occurred from 12.5 km from the mouth and this was also where the highest water column chlorophyll a (>20 μg l-1) was found. Different groups of microalgae formed phytoplankton blooms for the different sampling sessions, which were correlated with high chlorophyll a. These included blooms of green algae (August 2006), flagellates (March 2007), dinoflagellates (June 2008) and diatom species (February and August 2008). The dominant diatom (Cyclotella atomus) indicated nutrient-rich conditions. Green algae and diatoms were associated with low salinity water in the upper reaches of the estuary. Flagellates were dominant throughout the estuary particularly when nutrients were low, whereas the dinoflagellate bloom in June 2008 was correlated with high ammonium and pH. Maximum benthic chlorophyll a was found at 12.5 km from the mouth in February, June and August 2008 and was correlated with high sediment organic and moisture content. Benthic diatoms were associated with high temperature whereas some species in June 2008 were associated with high ammonium concentrations. The middle reaches of the estuary characterise a zone of deposition rather than suspension which would favour benthic diatom colonization. Phytoplankton cells settling out on the sediments may account for the high benthic chlorophyll a because maximum water column chlorophyll a was also found in the REI zone (where salinity is less than 10 percent and where high biological activity occurs) in the Sundays Estuary. The estuary was sampled over five consecutive weeks from March to April 2009 to identify environmental factors that support different microalgal bloom species. Phytoplankton blooms, defined as chlorophyll a greater than 20 μg l-1, were found during Weeks 1, 4 and 5 from the middle to the upper reaches of the estuary. Diatom species (Cylindrotheca closterium, Cyclotella atomus and Cyclostephanus dubius) occurred in bloom concentrations during these weeks. These diatom species are cosmopolitan and indicate brackish nutrient-rich water. Flagellates were the dominant group in Weeks 2 to 4, but positive correlations with chlorophyll a were found during Weeks 1 and 2. During the first week of this study the conditions were warm and calm (measured as temperature and wind speed) and there was a well developed bloom (38 μg l-1). There was a strong cold front from 17 to 19 March, which mixed the water column resulting in the decrease of the chlorophyll a levels (<20 μg l-1) and the bloom collapsed during Weeks 2 and 3. However, in Weeks 4 and 5 conditions were again calm and warmer, which appeared to stimulate the phytoplankton bloom. Nanoplankton (2.7 - 20 μm) was dominant during each week sampled and contributed a considerable amount (55 - 79 percent) to the phytoplankton biomass. Once again subtidal benthic chlorophyll a and water column chlorophyll a were highest 12.5 km from the mouth. Deposition of phytoplankton cells from the water column was evident in the benthic samples. The study showed that the Sundays Estuary is eutrophic and characterised by microalgal blooms consisting of different phytoplankton groups.
- Full Text:
- Date Issued: 2011
The response of microalgal biomass and community composition to environmental factors in the Sundays estuary
- Authors: Kotsedi, Daisy
- Date: 2011
- Subjects: Algal blooms -- South Africa -- Sundays River Estuary , Estuaries -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10636 , http://hdl.handle.net/10948/d1013611
- Description: The Sundays Estuary is permanently open to the sea and has been described as channel-like along its entire length with a narrow intertidal area (mostly less than 5 - 6 m in width). The estuary experiences regular freshwater inflow with large supplies of nutrients, derived from the Orange River transfer scheme and agricultural return flow. In particular, nitrate concentrations are high as a result of fertilisers used in the Sundays River catchment area. The objectives of this study were to measure microalgal biomass and community composition and relate to flow, water quality and other environmental variables. Surveys in August 2006, March 2007, February, June and August 2008 showed that salinity less than 10 percent mostly occurred from 12.5 km from the mouth and this was also where the highest water column chlorophyll a (>20 μg l-1) was found. Different groups of microalgae formed phytoplankton blooms for the different sampling sessions, which were correlated with high chlorophyll a. These included blooms of green algae (August 2006), flagellates (March 2007), dinoflagellates (June 2008) and diatom species (February and August 2008). The dominant diatom (Cyclotella atomus) indicated nutrient-rich conditions. Green algae and diatoms were associated with low salinity water in the upper reaches of the estuary. Flagellates were dominant throughout the estuary particularly when nutrients were low, whereas the dinoflagellate bloom in June 2008 was correlated with high ammonium and pH. Maximum benthic chlorophyll a was found at 12.5 km from the mouth in February, June and August 2008 and was correlated with high sediment organic and moisture content. Benthic diatoms were associated with high temperature whereas some species in June 2008 were associated with high ammonium concentrations. The middle reaches of the estuary characterise a zone of deposition rather than suspension which would favour benthic diatom colonization. Phytoplankton cells settling out on the sediments may account for the high benthic chlorophyll a because maximum water column chlorophyll a was also found in the REI zone (where salinity is less than 10 percent and where high biological activity occurs) in the Sundays Estuary.
- Full Text:
- Date Issued: 2011
- Authors: Kotsedi, Daisy
- Date: 2011
- Subjects: Algal blooms -- South Africa -- Sundays River Estuary , Estuaries -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10636 , http://hdl.handle.net/10948/d1013611
- Description: The Sundays Estuary is permanently open to the sea and has been described as channel-like along its entire length with a narrow intertidal area (mostly less than 5 - 6 m in width). The estuary experiences regular freshwater inflow with large supplies of nutrients, derived from the Orange River transfer scheme and agricultural return flow. In particular, nitrate concentrations are high as a result of fertilisers used in the Sundays River catchment area. The objectives of this study were to measure microalgal biomass and community composition and relate to flow, water quality and other environmental variables. Surveys in August 2006, March 2007, February, June and August 2008 showed that salinity less than 10 percent mostly occurred from 12.5 km from the mouth and this was also where the highest water column chlorophyll a (>20 μg l-1) was found. Different groups of microalgae formed phytoplankton blooms for the different sampling sessions, which were correlated with high chlorophyll a. These included blooms of green algae (August 2006), flagellates (March 2007), dinoflagellates (June 2008) and diatom species (February and August 2008). The dominant diatom (Cyclotella atomus) indicated nutrient-rich conditions. Green algae and diatoms were associated with low salinity water in the upper reaches of the estuary. Flagellates were dominant throughout the estuary particularly when nutrients were low, whereas the dinoflagellate bloom in June 2008 was correlated with high ammonium and pH. Maximum benthic chlorophyll a was found at 12.5 km from the mouth in February, June and August 2008 and was correlated with high sediment organic and moisture content. Benthic diatoms were associated with high temperature whereas some species in June 2008 were associated with high ammonium concentrations. The middle reaches of the estuary characterise a zone of deposition rather than suspension which would favour benthic diatom colonization. Phytoplankton cells settling out on the sediments may account for the high benthic chlorophyll a because maximum water column chlorophyll a was also found in the REI zone (where salinity is less than 10 percent and where high biological activity occurs) in the Sundays Estuary.
- Full Text:
- Date Issued: 2011
The role of Hsp90 in the Wnt pathway of MCF7 breast cancer cells
- Authors: Cooper, Leanne Claire
- Date: 2011
- Subjects: Cancer -- Treatment , Heat shock proteins , Cancer cells , Molecular chaperones
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3985 , http://hdl.handle.net/10962/d1004044 , Cancer -- Treatment , Heat shock proteins , Cancer cells , Molecular chaperones
- Description: Breast cancer is one of the most common forms of cancer in not only South African women, but women all over the world. The molecular chaperone heat shock protein 90 (HSP90) is upregulated in cancer and is almost exclusively associated with proteins involved in intracellular signal transduction, thus it plays an important role in signalling pathways within the cell. In cancer, there is an aberrant activation of the Wnt signaling pathway, which results in stabilized β-catenin being able to translocate to the nucleus where it can trigger the transcription of oncogenes found to be involved in the self-renewal of cells. The level of β-catenin is usually kept in check by a destruction complex comprising glycogen synthase kinase 3-beta (GSK-3β), axin1, adenomatous polyposis coli (APC) which phosphorylate β-catenin, resulting in its ubiquitination and degradation. HSP90 has been found to be associated with GSK-3β, but whether this association is only transient is debatable. Very little is known about the association of HSP90 with other members of the Wnt pathway in breast cancer. In this study, we have attempted to further identify the direct associations between HSP90 and GSK-3β, β-catenin, p-β-catenin and axin1. Immunofluorescence and confocal microscopy co-localization studies suggested a potential association between HSP90 and these proteins. Treatment with HSP90 inhibitors, 17-AAG and novobiocin resulted in a shift of axin1 to what appeared to be the plasma membrane. The associations of HSP90 with GSK-3β, β-catenin, p-β-catenin and axin1 were confirmed biochemically by co-immunoprecipitation and inhibition using 17-AAG, geldanamycin and novobiocin. We showed, for the first time that HSP90 is associated in a possible complex with β-catenin, p-β-catenin and axin1 therefore is potentially involved in the modulation of p-β-catenin in the Wnt pathway through the stabilization of the destruction complex.
- Full Text:
- Date Issued: 2011
- Authors: Cooper, Leanne Claire
- Date: 2011
- Subjects: Cancer -- Treatment , Heat shock proteins , Cancer cells , Molecular chaperones
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3985 , http://hdl.handle.net/10962/d1004044 , Cancer -- Treatment , Heat shock proteins , Cancer cells , Molecular chaperones
- Description: Breast cancer is one of the most common forms of cancer in not only South African women, but women all over the world. The molecular chaperone heat shock protein 90 (HSP90) is upregulated in cancer and is almost exclusively associated with proteins involved in intracellular signal transduction, thus it plays an important role in signalling pathways within the cell. In cancer, there is an aberrant activation of the Wnt signaling pathway, which results in stabilized β-catenin being able to translocate to the nucleus where it can trigger the transcription of oncogenes found to be involved in the self-renewal of cells. The level of β-catenin is usually kept in check by a destruction complex comprising glycogen synthase kinase 3-beta (GSK-3β), axin1, adenomatous polyposis coli (APC) which phosphorylate β-catenin, resulting in its ubiquitination and degradation. HSP90 has been found to be associated with GSK-3β, but whether this association is only transient is debatable. Very little is known about the association of HSP90 with other members of the Wnt pathway in breast cancer. In this study, we have attempted to further identify the direct associations between HSP90 and GSK-3β, β-catenin, p-β-catenin and axin1. Immunofluorescence and confocal microscopy co-localization studies suggested a potential association between HSP90 and these proteins. Treatment with HSP90 inhibitors, 17-AAG and novobiocin resulted in a shift of axin1 to what appeared to be the plasma membrane. The associations of HSP90 with GSK-3β, β-catenin, p-β-catenin and axin1 were confirmed biochemically by co-immunoprecipitation and inhibition using 17-AAG, geldanamycin and novobiocin. We showed, for the first time that HSP90 is associated in a possible complex with β-catenin, p-β-catenin and axin1 therefore is potentially involved in the modulation of p-β-catenin in the Wnt pathway through the stabilization of the destruction complex.
- Full Text:
- Date Issued: 2011
The spatial evolution of the chemotaxis proteins of the Bacillus subtilis group
- Yssel, Anna Elizabeth Johanna
- Authors: Yssel, Anna Elizabeth Johanna
- Date: 2011
- Subjects: Chemotaxis , Bacillus subtilis , Bacillus (Bacteria) , Homology (Biology) , Plants -- Microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4027 , http://hdl.handle.net/10962/d1004087 , Chemotaxis , Bacillus subtilis , Bacillus (Bacteria) , Homology (Biology) , Plants -- Microbiology
- Description: The aim of this work was to study spatial evolution of the chemotaxis proteins of a group of plant-associated soil-dwelling bacteria vernacularly referred to as the B. subtilis group. This was achieved by creating homology models for the chemotaxis proteins if a suitable template was available, and by analysing the selective forces (positive, purifying or neutral) acting upon the chemotaxis proteins. Chemotaxis is the phenomenon in which bacteria direct their movement towards more favourable conditions, and is critical for processes such as obtaining nutrients, escaping toxic compounds, host colonization and bio-film formation. Members of the B. subtilis group exhibit different preferences for certain host plants, and it is therefore feasible that their chemotactic machinery are fine-tuned to respond optimally to the conditions of the various niches that the strains inhabit. Homology models were inferred for the plant growth promoting B. amyloliquefaciens FZB42 proteins CheB, CheC, CheD, CheR, CheW and CheY. The interactions between: CheC-CheD, the P1 and P2 domains of CheA with CheY and CheB, and the P4 and P5 domains of CheA with CheW were also modelled. The hydrophobic interactions contributing to intra- and inter-protein contacts were analysed. The models of the interactions between CheB and the various domains of CheA are of particular interest, because to date no structures have been solved that show an interaction between a histidine kinase (such as CheA) and a multidomain response regulator (such as CheB). Furthermore, evidence that phospho-CheB may inhibit the formation of phospho-CheY by competitively binding to the P2 domain of CheA is also presented. Proteins were analysed to determine if individual amino acid sites are under positive, neutral or purifying selection. The Methyl Accepting Chemotaxis Proteins (MCPs), CheA and CheV were also analyzed, but due to a lack of suitable templates, no homology models were constructed. Site-specific positive and purifying selection were estimated by comparing the ratios of non-synonymous to synonymous substitutions at each site in the sequences for the chemotaxis proteins as well as for the receptors McpA, McpB, and McpC. Homology models were coloured according to intensity of selective forces. It was found that the chemotaxis proteins of member of the B. subtilis group are under strong evolutionary constraints, hence it is unlikely that positive selection in these proteins are responsible for the differences in habitat preference that these organism exhibit.
- Full Text:
- Date Issued: 2011
- Authors: Yssel, Anna Elizabeth Johanna
- Date: 2011
- Subjects: Chemotaxis , Bacillus subtilis , Bacillus (Bacteria) , Homology (Biology) , Plants -- Microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4027 , http://hdl.handle.net/10962/d1004087 , Chemotaxis , Bacillus subtilis , Bacillus (Bacteria) , Homology (Biology) , Plants -- Microbiology
- Description: The aim of this work was to study spatial evolution of the chemotaxis proteins of a group of plant-associated soil-dwelling bacteria vernacularly referred to as the B. subtilis group. This was achieved by creating homology models for the chemotaxis proteins if a suitable template was available, and by analysing the selective forces (positive, purifying or neutral) acting upon the chemotaxis proteins. Chemotaxis is the phenomenon in which bacteria direct their movement towards more favourable conditions, and is critical for processes such as obtaining nutrients, escaping toxic compounds, host colonization and bio-film formation. Members of the B. subtilis group exhibit different preferences for certain host plants, and it is therefore feasible that their chemotactic machinery are fine-tuned to respond optimally to the conditions of the various niches that the strains inhabit. Homology models were inferred for the plant growth promoting B. amyloliquefaciens FZB42 proteins CheB, CheC, CheD, CheR, CheW and CheY. The interactions between: CheC-CheD, the P1 and P2 domains of CheA with CheY and CheB, and the P4 and P5 domains of CheA with CheW were also modelled. The hydrophobic interactions contributing to intra- and inter-protein contacts were analysed. The models of the interactions between CheB and the various domains of CheA are of particular interest, because to date no structures have been solved that show an interaction between a histidine kinase (such as CheA) and a multidomain response regulator (such as CheB). Furthermore, evidence that phospho-CheB may inhibit the formation of phospho-CheY by competitively binding to the P2 domain of CheA is also presented. Proteins were analysed to determine if individual amino acid sites are under positive, neutral or purifying selection. The Methyl Accepting Chemotaxis Proteins (MCPs), CheA and CheV were also analyzed, but due to a lack of suitable templates, no homology models were constructed. Site-specific positive and purifying selection were estimated by comparing the ratios of non-synonymous to synonymous substitutions at each site in the sequences for the chemotaxis proteins as well as for the receptors McpA, McpB, and McpC. Homology models were coloured according to intensity of selective forces. It was found that the chemotaxis proteins of member of the B. subtilis group are under strong evolutionary constraints, hence it is unlikely that positive selection in these proteins are responsible for the differences in habitat preference that these organism exhibit.
- Full Text:
- Date Issued: 2011
The use of fish species in a marine conservation plan for KwaZulu-Natal
- Authors: Haupt, Philip
- Date: 2011
- Subjects: Fishery conservation -- South Africa -- KwaZulu Natal , Marine resources conservation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10681 , http://hdl.handle.net/10948/1528 , Fishery conservation -- South Africa -- KwaZulu Natal , Marine resources conservation
- Description: This study formed part of a larger provincial marine systematic conservation plan for KwaZulu-Natal (KZN), South Africa, called SeaPLAN. Owing to budget and time constraints, not all ± 1640 fish species that occur in the region were considered. A method to prioritise species was therefore developed to identify those species which were most at most risk of being excluded by a conservation plan based primarily on habitat representation (i.e. SeaPLAN). The method was based on three underlying principles: (i) species with limited conservation options; (ii) threatened species; and (iii) inherently vulnerable species. From these three principles, seven criteria were defined (e.g. endemic or rare species). Sixtyseven species met the qualifying conditions for these criteria and were consequently included in this study (FishPLAN). In order to map the distributions of these 67 fish species, the spatial and temporal accuracy of existing marine fish data for KZN was investigated. Only 17 percent of the data evaluated met the spatial resolution requirements of 1 km2, while temporal resolution was high: >99 percent of the data were collected at daily resolution. A resulting recommendation is that future data collection employ handheld data recording devices (with GPS capability), in order to increase the spatial accuracy of data, minimise human error and improve the efficiency of data flow. Species life cycle envelopes (SLICES) were developed to capture spatial differences in areas occupied during three life-cycle phases (reproductive, juvenile and feeding). Two distribution modelling techniques were used: Maxent, which uses quantitative data, and CHARMS (cartographic habitat association range models), which uses qualitative range data. A combination of statistical and biological criteria was used to determine the most informative and appropriate model for each species. Species distribution models (SDMs) were constructed for three temporal partitions of the data: annual, summer and winter. Patterns of species richness developed from the seasonal models showed seasonal differences in patterns that conformed to known seasonal distributions of fish assemblages: richness was higher in southern KZN during winter, while it was higher in northern KZN during summer. The resulting SDMs were used to develop a conservation plan for fish: conservation targets were set using the minimum recommended baseline of 20 percent of a species’ range, to which biological retention targets (additional proportion of the range) were added, in an attempt to ensure species persistence. The conservation targets were then adjusted using catch per unit effort (CPUE) data to match seasonal abundance of a given species. Within the existing network of marine protected areas (MPAs), none of the species’ targets are met by MPA sanctuary zones (zone As) alone, and all species require greater areas of protection. Three areas, namely offshore of the Tugela River mouth, the reefs offshore of Durban, and Aliwal Shoal, were consistently identified as being important in addition to existing MPAs for conservation of the fish species investigated. The greater efficiency of a seasonal MPA network to protect seasonally varying distributions of biodiversity, suggests that this may be a useful tool to consider in conservation management. The outcome of a conservation plan from this study (FishPLAN) was finally compared with the broader, more inclusive conservation plan, SeaPLAN. This comparison demonstrated how conservation plans based on a single group of species run the risk of identifying areas that are appropriate only for the relevant species, and might fail to conserve biodiversity as a whole.
- Full Text:
- Date Issued: 2011
- Authors: Haupt, Philip
- Date: 2011
- Subjects: Fishery conservation -- South Africa -- KwaZulu Natal , Marine resources conservation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10681 , http://hdl.handle.net/10948/1528 , Fishery conservation -- South Africa -- KwaZulu Natal , Marine resources conservation
- Description: This study formed part of a larger provincial marine systematic conservation plan for KwaZulu-Natal (KZN), South Africa, called SeaPLAN. Owing to budget and time constraints, not all ± 1640 fish species that occur in the region were considered. A method to prioritise species was therefore developed to identify those species which were most at most risk of being excluded by a conservation plan based primarily on habitat representation (i.e. SeaPLAN). The method was based on three underlying principles: (i) species with limited conservation options; (ii) threatened species; and (iii) inherently vulnerable species. From these three principles, seven criteria were defined (e.g. endemic or rare species). Sixtyseven species met the qualifying conditions for these criteria and were consequently included in this study (FishPLAN). In order to map the distributions of these 67 fish species, the spatial and temporal accuracy of existing marine fish data for KZN was investigated. Only 17 percent of the data evaluated met the spatial resolution requirements of 1 km2, while temporal resolution was high: >99 percent of the data were collected at daily resolution. A resulting recommendation is that future data collection employ handheld data recording devices (with GPS capability), in order to increase the spatial accuracy of data, minimise human error and improve the efficiency of data flow. Species life cycle envelopes (SLICES) were developed to capture spatial differences in areas occupied during three life-cycle phases (reproductive, juvenile and feeding). Two distribution modelling techniques were used: Maxent, which uses quantitative data, and CHARMS (cartographic habitat association range models), which uses qualitative range data. A combination of statistical and biological criteria was used to determine the most informative and appropriate model for each species. Species distribution models (SDMs) were constructed for three temporal partitions of the data: annual, summer and winter. Patterns of species richness developed from the seasonal models showed seasonal differences in patterns that conformed to known seasonal distributions of fish assemblages: richness was higher in southern KZN during winter, while it was higher in northern KZN during summer. The resulting SDMs were used to develop a conservation plan for fish: conservation targets were set using the minimum recommended baseline of 20 percent of a species’ range, to which biological retention targets (additional proportion of the range) were added, in an attempt to ensure species persistence. The conservation targets were then adjusted using catch per unit effort (CPUE) data to match seasonal abundance of a given species. Within the existing network of marine protected areas (MPAs), none of the species’ targets are met by MPA sanctuary zones (zone As) alone, and all species require greater areas of protection. Three areas, namely offshore of the Tugela River mouth, the reefs offshore of Durban, and Aliwal Shoal, were consistently identified as being important in addition to existing MPAs for conservation of the fish species investigated. The greater efficiency of a seasonal MPA network to protect seasonally varying distributions of biodiversity, suggests that this may be a useful tool to consider in conservation management. The outcome of a conservation plan from this study (FishPLAN) was finally compared with the broader, more inclusive conservation plan, SeaPLAN. This comparison demonstrated how conservation plans based on a single group of species run the risk of identifying areas that are appropriate only for the relevant species, and might fail to conserve biodiversity as a whole.
- Full Text:
- Date Issued: 2011
The value added by facilities management services to an organisation's core business
- Authors: Relu, Lona
- Date: 2011
- Subjects: Facility management , Production management , Operations management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9724 , http://hdl.handle.net/10948/d1012047 , Facility management , Production management , Operations management
- Description: The main objective of the study was to define FM in its broader context and identify ways of exposing its value to the organisation’s core business. The study firstly included defining FM, its scope and nature to provide an in-depth overview and understanding of the discipline. Secondly, the study discussed in detail the level of support of FM by top or senior management. Thirdly, the study discussed the importance of quality management in enhancing the value of FM within an organisation. Lastly, the study discussed how service level agreements can be utilised to enhance the value of FM within the organisation. Questionnaires were distributed via electronic mail and some hand-delivered to private, public organisations and government parastatals to gather their views on how they think FM can add value to their organisations. Questionnaires were sent out to various professionals from various organisations that employ FM services based on the aforementioned objectives. The findings from the survey showed that most organisations understand and have the knowledge about FM but there is no set and defined scope; the scope of FM differs in various organisations; soft services are grouped together and branded as FM services; FM is moderately incorporated throughout and top management still sees FM as adding no value to the organisation’s core business. The results also show that FM needs to adopt strategies such as understanding and working towards the organisation’s goals and objectives; ensuring sustainability in FM services; providing superior quality service and projecting defined and improved levels of service linking service to the organisation’s culture and facilitating organisational change for it to gain support from top management. The majority of respondents incorporating FM in their organisations agree with the benefits afforded by this discipline and have developed and implemented quality management systems that are linked to their business strategies and, by doing so, have enhanced their organisation’s performance levels. Service Level agreements are not being utilised by the majority of the organisations the few organisations that utilise SLA’s, have benefited a great deal from SLAs.
- Full Text:
- Date Issued: 2011
- Authors: Relu, Lona
- Date: 2011
- Subjects: Facility management , Production management , Operations management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9724 , http://hdl.handle.net/10948/d1012047 , Facility management , Production management , Operations management
- Description: The main objective of the study was to define FM in its broader context and identify ways of exposing its value to the organisation’s core business. The study firstly included defining FM, its scope and nature to provide an in-depth overview and understanding of the discipline. Secondly, the study discussed in detail the level of support of FM by top or senior management. Thirdly, the study discussed the importance of quality management in enhancing the value of FM within an organisation. Lastly, the study discussed how service level agreements can be utilised to enhance the value of FM within the organisation. Questionnaires were distributed via electronic mail and some hand-delivered to private, public organisations and government parastatals to gather their views on how they think FM can add value to their organisations. Questionnaires were sent out to various professionals from various organisations that employ FM services based on the aforementioned objectives. The findings from the survey showed that most organisations understand and have the knowledge about FM but there is no set and defined scope; the scope of FM differs in various organisations; soft services are grouped together and branded as FM services; FM is moderately incorporated throughout and top management still sees FM as adding no value to the organisation’s core business. The results also show that FM needs to adopt strategies such as understanding and working towards the organisation’s goals and objectives; ensuring sustainability in FM services; providing superior quality service and projecting defined and improved levels of service linking service to the organisation’s culture and facilitating organisational change for it to gain support from top management. The majority of respondents incorporating FM in their organisations agree with the benefits afforded by this discipline and have developed and implemented quality management systems that are linked to their business strategies and, by doing so, have enhanced their organisation’s performance levels. Service Level agreements are not being utilised by the majority of the organisations the few organisations that utilise SLA’s, have benefited a great deal from SLAs.
- Full Text:
- Date Issued: 2011
The value of remnant habitat patches for conserving butterflies (Lepidoptera) in King Sabata Dalindyebo (KSD) Local Municipality, Eastern Cape, South Africa
- Authors: Avuletey, Richard
- Date: 2011
- Subjects: Butterflies -- Research Butterflies -- Behaviour South Africa -- Transkei
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:18490 , http://hdl.handle.net/11260/d1011285
- Description: Butterflies (Lepidoptera) have attracted more attention as indicators of terrestrial ecosystems than other invertebrates. This taxon is widely used as tools or subjects for biodiversity conservation planning in the Northern and Southern Hemispheres. The study determined butterfly species turnover at a-priori selected habitat patches in a protected area (Nduli Nature Reserve) and non-formally protected areas (outside Nduli Nature Reserve) of the KSD Local Municipality and their response to measured environmental variables. Using transect survey methods, 516 butterfly individuals belonging to 22 species were caught from 16 sampling units. Species dominance curves showed more butterfly species evenness outside reserve sites than inside. Hierarchical clustering using Bray-Curtis similarity matrices and Correspondence analysis (CA) grouped sampling units according to butterfly species sampled. Site habitat patches outside the reserve were richer in butterfly and overall abundance than inside the reserve. The Canonical Correspondence analysis (CCA) results revealed that certain site variables such as percentage herb cover, area of patch size, average grass height, grazing intensity, distance to the city centre and average flower density accounted for species distribution patterns at various sampling units. The conservation implications of the study suggest that patch level management of micro-habitats with sufficient flowering herbs, structural vegetation, and patch size with minimal disturbance within and outside reserve areas can encourage rare and common butterfly species richness and diversity.
- Full Text:
- Date Issued: 2011
- Authors: Avuletey, Richard
- Date: 2011
- Subjects: Butterflies -- Research Butterflies -- Behaviour South Africa -- Transkei
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:18490 , http://hdl.handle.net/11260/d1011285
- Description: Butterflies (Lepidoptera) have attracted more attention as indicators of terrestrial ecosystems than other invertebrates. This taxon is widely used as tools or subjects for biodiversity conservation planning in the Northern and Southern Hemispheres. The study determined butterfly species turnover at a-priori selected habitat patches in a protected area (Nduli Nature Reserve) and non-formally protected areas (outside Nduli Nature Reserve) of the KSD Local Municipality and their response to measured environmental variables. Using transect survey methods, 516 butterfly individuals belonging to 22 species were caught from 16 sampling units. Species dominance curves showed more butterfly species evenness outside reserve sites than inside. Hierarchical clustering using Bray-Curtis similarity matrices and Correspondence analysis (CA) grouped sampling units according to butterfly species sampled. Site habitat patches outside the reserve were richer in butterfly and overall abundance than inside the reserve. The Canonical Correspondence analysis (CCA) results revealed that certain site variables such as percentage herb cover, area of patch size, average grass height, grazing intensity, distance to the city centre and average flower density accounted for species distribution patterns at various sampling units. The conservation implications of the study suggest that patch level management of micro-habitats with sufficient flowering herbs, structural vegetation, and patch size with minimal disturbance within and outside reserve areas can encourage rare and common butterfly species richness and diversity.
- Full Text:
- Date Issued: 2011
The zoogeography of the cetaceans in Algoa Bay
- Authors: Melly, Brigitte Leigh
- Date: 2011
- Subjects: Cetacea -- South Africa -- Algoa Bay , Cetacea -- Behavior -- South Africa -- Algoa Bay , Cetacea -- South Africa -- Algoa Bay -- Geographical distribution , Cetacea -- Counting -- South Africa -- Algoa Bay
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4858 , http://hdl.handle.net/10962/d1005534 , Cetacea -- South Africa -- Algoa Bay , Cetacea -- Behavior -- South Africa -- Algoa Bay , Cetacea -- South Africa -- Algoa Bay -- Geographical distribution , Cetacea -- Counting -- South Africa -- Algoa Bay
- Description: The most recent study on cetaceans in Algoa Bay, South Africa, was conducted over 14 years ago. Consequently, knowledge of the cetacean species visiting this bay is currently based on incidental observations and stranding data. A number of developments in recent years: a deepwater port, proposed oil refinery, increased boating and fishing (commercial and recreational), a proposed Marine Protected Area, and the release of a whale-watching permit, all of which may impact these animals in some way, highlight the need for a baseline study on cetaceans. Therefore, the aim of this study was to determine the spatial and temporal distribution, and habitat preference of cetaceans in Algoa Bay. Boat-based surveys were conducted monthly between March 2009 and July 2010. At each sighting the GPS location, species, group size and composition, and behaviour were recorded. Using GIS, the sighting data was related to data layers of geographical variables such as sea surface temperature, depth and sea-floor substrate. Approximately 365 hours of search effort were completed over 57 surveys, with a total of 346 sightings. Species observed were: southern right whales (Eubalaena australis), humpback whales (Megaptera novaeangliae), Bryde’s whales (Balaenoptera brydei), Indian Ocean bottlenose dolphins (Tursiops aduncus), Indo-Pacific humpback dolphins (Sousa chinensis), and longbeaked common dolphins (Delphinus capensis). Southern right whales were observed during austral winter, utilising the shallow, protected areas of the bay as a mating and nursery ground. Humpback whales were also recorded extensively during winter, in more offshore waters, with a significant number of mother-calf pairs sighted. Bryde’s whales were recorded in offshore waters during summer and autumn, where they were primarily observed travelling and foraging. Bottlenose dolphins were the most prolific species sighted. They were recorded year-round throughout the inshore waters of the bay, with large group sizes (up to 500 animals), and displayed a wide variety of behaviours. Humpback dolphins were observed in extremely shallow and inshore waters (mean bottom depth of 6.6 m) along the south-west corner of the bay, in small groups of approximately three individuals. Common dolphins were the least observed species, and were mainly observed foraging in large groups of up to 800 individuals. The results of this study indicate how cetaceans utilise the bay in significantly different ways. Geographical and anthropogenic factors have influenced the spatial and temporal distribution of these animals and have resulted in habitat preferences, as well as potential key habitats, in the bay. Thus, this study has provided baseline information for future research and for better informed conservation and management strategies in Algoa Bay.
- Full Text:
- Date Issued: 2011
- Authors: Melly, Brigitte Leigh
- Date: 2011
- Subjects: Cetacea -- South Africa -- Algoa Bay , Cetacea -- Behavior -- South Africa -- Algoa Bay , Cetacea -- South Africa -- Algoa Bay -- Geographical distribution , Cetacea -- Counting -- South Africa -- Algoa Bay
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4858 , http://hdl.handle.net/10962/d1005534 , Cetacea -- South Africa -- Algoa Bay , Cetacea -- Behavior -- South Africa -- Algoa Bay , Cetacea -- South Africa -- Algoa Bay -- Geographical distribution , Cetacea -- Counting -- South Africa -- Algoa Bay
- Description: The most recent study on cetaceans in Algoa Bay, South Africa, was conducted over 14 years ago. Consequently, knowledge of the cetacean species visiting this bay is currently based on incidental observations and stranding data. A number of developments in recent years: a deepwater port, proposed oil refinery, increased boating and fishing (commercial and recreational), a proposed Marine Protected Area, and the release of a whale-watching permit, all of which may impact these animals in some way, highlight the need for a baseline study on cetaceans. Therefore, the aim of this study was to determine the spatial and temporal distribution, and habitat preference of cetaceans in Algoa Bay. Boat-based surveys were conducted monthly between March 2009 and July 2010. At each sighting the GPS location, species, group size and composition, and behaviour were recorded. Using GIS, the sighting data was related to data layers of geographical variables such as sea surface temperature, depth and sea-floor substrate. Approximately 365 hours of search effort were completed over 57 surveys, with a total of 346 sightings. Species observed were: southern right whales (Eubalaena australis), humpback whales (Megaptera novaeangliae), Bryde’s whales (Balaenoptera brydei), Indian Ocean bottlenose dolphins (Tursiops aduncus), Indo-Pacific humpback dolphins (Sousa chinensis), and longbeaked common dolphins (Delphinus capensis). Southern right whales were observed during austral winter, utilising the shallow, protected areas of the bay as a mating and nursery ground. Humpback whales were also recorded extensively during winter, in more offshore waters, with a significant number of mother-calf pairs sighted. Bryde’s whales were recorded in offshore waters during summer and autumn, where they were primarily observed travelling and foraging. Bottlenose dolphins were the most prolific species sighted. They were recorded year-round throughout the inshore waters of the bay, with large group sizes (up to 500 animals), and displayed a wide variety of behaviours. Humpback dolphins were observed in extremely shallow and inshore waters (mean bottom depth of 6.6 m) along the south-west corner of the bay, in small groups of approximately three individuals. Common dolphins were the least observed species, and were mainly observed foraging in large groups of up to 800 individuals. The results of this study indicate how cetaceans utilise the bay in significantly different ways. Geographical and anthropogenic factors have influenced the spatial and temporal distribution of these animals and have resulted in habitat preferences, as well as potential key habitats, in the bay. Thus, this study has provided baseline information for future research and for better informed conservation and management strategies in Algoa Bay.
- Full Text:
- Date Issued: 2011
Towards a sustainable bioprocess for the remediation of acid mine drainage
- Authors: Mambo, Mutsa Prudence
- Date: 2011
- Subjects: Acid mine drainage , Algae culture , Reduction (Chemistry) , Hydrolysis , ASPAM model (Acid mine drainage) , Water -- Purification
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5955 , http://hdl.handle.net/10962/d1006167 , Acid mine drainage , Algae culture , Reduction (Chemistry) , Hydrolysis , ASPAM model (Acid mine drainage) , Water -- Purification
- Description: Acid mine drainage is of growing concern for both developing and developed economies. Thus there is increasing pressure to develop alternative remediation strategies. Biological sulphidogenic mechanisms have long since been studied but, very few have been implemented on a large scale. Limitations are due to the inability to acquire a suitable, low cost, environmentally friendly, renewable carbon source. The present study investigated the use of an algae biomass generated by the HRAOP of an IAPS as a carbon source for the EBRU 00AB/06 SRB consortium. The algae biomass and consortium were utilized together to remediate simulated AMD. Remediation involved decreasing the sulphate and metal concentrations in solution and decreasing the acidity of a simulated AMD. Experiments were carried out to investigate the capability of the EBRU 00AB/06 SRB consortium for sulphate reduction and sulphide generation. The consortium produced colonies when grown under anaerobic conditions in Petri dishes containing modified lactate SRB medium. The SRB consortium reduced the sulphate concentration of modified Postgates medium B and generated sulphide. Further analysis of the EBRU 00AB/06 SRB consortium revealed that the consortium was minimally impacted at pH 5 and by sulphate and iron at 3 g.L-1 and 0.5 g.L-1 respectively. The EBRU 00AB/06 SRB consortium was exposed to Actinomycin D and Ethidium Bromide to determine whether transcription and translation of proteins was required for sulphate reduction. Results indicated that sulphide generation and sulphate reduction were inducible. Analysis of the algae biomass used in this study revealed the empirical formula C1.0H1.91N0.084S0.003O0.36 indicating a carbon source rich in the nutrients required to sustain microbial development. Light microscopy revealed that algae cell walls and in particular those of Pediastrum were susceptible to acid hydrolysis. Dinitrosalicylic acid, Nile red, Bradford and Ninhydrin assays were used to determine the reducing sugar, lipid, protein and amino acid content respectively, of the mixed algae biomass. Results showed that upon exposure of the biomass to simulated AMD at pH 1 and pH 3, the concentration of reducing sugars and amino acids in solution increased. Whereas levels of lipids remained unchanged while the protein concentration decreased, indicating that, upon exposure of algae biomass to AMD, simulated or otherwise, cells ruptured, proteins were hydrolyzed and polysaccharides were broken down to sugars which are immediately available for SRB utilization. Exposure of biomass to simulated AMD revealed further that the presence of algae biomass increased the pH of simulated AMD (pH 3) to pH 7.67 after 4 d. Likewise, the pH of simulated AMD at 1 increased to 1.77 after 2 d while pH of the neutral control increased to 8.1 after 4 d. A direct comparison between lactate and algae biomass revealed 94 % sulphate removal after 23 d in the presence of algae biomass while 82 % sulphate removal was measured in the presence of lactate. Thus the EBRU 00AB/06 SRB consortium successfully utilized algae biomass for sulphate reduction and sulphide generation. In another experiment to establish if the consortium could remediate simulated AMD (pH 5) containing 0.5 g.L-1 iron and 3 g.L-1 sulphate while utilizing an algae biomass as the carbon source no residual iron was detected after 14 d and by day 23, an 89.07 % reduction in sulphate was measured. The results of this investigation are discussed in terms of utilizing a readily available and renewable biomass in the form of microalgae produced in HRAOPs as an effective carbon source in the SRB catalysed remediation of AMD.
- Full Text:
- Date Issued: 2011
- Authors: Mambo, Mutsa Prudence
- Date: 2011
- Subjects: Acid mine drainage , Algae culture , Reduction (Chemistry) , Hydrolysis , ASPAM model (Acid mine drainage) , Water -- Purification
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5955 , http://hdl.handle.net/10962/d1006167 , Acid mine drainage , Algae culture , Reduction (Chemistry) , Hydrolysis , ASPAM model (Acid mine drainage) , Water -- Purification
- Description: Acid mine drainage is of growing concern for both developing and developed economies. Thus there is increasing pressure to develop alternative remediation strategies. Biological sulphidogenic mechanisms have long since been studied but, very few have been implemented on a large scale. Limitations are due to the inability to acquire a suitable, low cost, environmentally friendly, renewable carbon source. The present study investigated the use of an algae biomass generated by the HRAOP of an IAPS as a carbon source for the EBRU 00AB/06 SRB consortium. The algae biomass and consortium were utilized together to remediate simulated AMD. Remediation involved decreasing the sulphate and metal concentrations in solution and decreasing the acidity of a simulated AMD. Experiments were carried out to investigate the capability of the EBRU 00AB/06 SRB consortium for sulphate reduction and sulphide generation. The consortium produced colonies when grown under anaerobic conditions in Petri dishes containing modified lactate SRB medium. The SRB consortium reduced the sulphate concentration of modified Postgates medium B and generated sulphide. Further analysis of the EBRU 00AB/06 SRB consortium revealed that the consortium was minimally impacted at pH 5 and by sulphate and iron at 3 g.L-1 and 0.5 g.L-1 respectively. The EBRU 00AB/06 SRB consortium was exposed to Actinomycin D and Ethidium Bromide to determine whether transcription and translation of proteins was required for sulphate reduction. Results indicated that sulphide generation and sulphate reduction were inducible. Analysis of the algae biomass used in this study revealed the empirical formula C1.0H1.91N0.084S0.003O0.36 indicating a carbon source rich in the nutrients required to sustain microbial development. Light microscopy revealed that algae cell walls and in particular those of Pediastrum were susceptible to acid hydrolysis. Dinitrosalicylic acid, Nile red, Bradford and Ninhydrin assays were used to determine the reducing sugar, lipid, protein and amino acid content respectively, of the mixed algae biomass. Results showed that upon exposure of the biomass to simulated AMD at pH 1 and pH 3, the concentration of reducing sugars and amino acids in solution increased. Whereas levels of lipids remained unchanged while the protein concentration decreased, indicating that, upon exposure of algae biomass to AMD, simulated or otherwise, cells ruptured, proteins were hydrolyzed and polysaccharides were broken down to sugars which are immediately available for SRB utilization. Exposure of biomass to simulated AMD revealed further that the presence of algae biomass increased the pH of simulated AMD (pH 3) to pH 7.67 after 4 d. Likewise, the pH of simulated AMD at 1 increased to 1.77 after 2 d while pH of the neutral control increased to 8.1 after 4 d. A direct comparison between lactate and algae biomass revealed 94 % sulphate removal after 23 d in the presence of algae biomass while 82 % sulphate removal was measured in the presence of lactate. Thus the EBRU 00AB/06 SRB consortium successfully utilized algae biomass for sulphate reduction and sulphide generation. In another experiment to establish if the consortium could remediate simulated AMD (pH 5) containing 0.5 g.L-1 iron and 3 g.L-1 sulphate while utilizing an algae biomass as the carbon source no residual iron was detected after 14 d and by day 23, an 89.07 % reduction in sulphate was measured. The results of this investigation are discussed in terms of utilizing a readily available and renewable biomass in the form of microalgae produced in HRAOPs as an effective carbon source in the SRB catalysed remediation of AMD.
- Full Text:
- Date Issued: 2011
Universal approximation properties of feedforward artificial neural networks.
- Authors: Redpath, Stuart Frederick
- Date: 2011
- Subjects: Neural networks (Computer science) , Artificial intelligence -- Biological applications , Functional analysis , Weierstrass-Stone Theorem , Banach-Hahn theorem
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5430 , http://hdl.handle.net/10962/d1015869
- Description: In this thesis we summarise several results in the literature which show the approximation capabilities of multilayer feedforward artificial neural networks. We show that multilayer feedforward artificial neural networks are capable of approximating continuous and measurable functions from Rn to R to any degree of accuracy under certain conditions. In particular making use of the Stone-Weierstrass and Hahn-Banach theorems, we show that a multilayer feedforward artificial neural network can approximate any continuous function to any degree of accuracy, by using either an arbitrary squashing function or any continuous sigmoidal function for activation. Making use of the Stone-Weirstrass Theorem again, we extend these approximation capabilities of multilayer feedforward artificial neural networks to the space of measurable functions under any probability measure.
- Full Text:
- Date Issued: 2011
- Authors: Redpath, Stuart Frederick
- Date: 2011
- Subjects: Neural networks (Computer science) , Artificial intelligence -- Biological applications , Functional analysis , Weierstrass-Stone Theorem , Banach-Hahn theorem
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5430 , http://hdl.handle.net/10962/d1015869
- Description: In this thesis we summarise several results in the literature which show the approximation capabilities of multilayer feedforward artificial neural networks. We show that multilayer feedforward artificial neural networks are capable of approximating continuous and measurable functions from Rn to R to any degree of accuracy under certain conditions. In particular making use of the Stone-Weierstrass and Hahn-Banach theorems, we show that a multilayer feedforward artificial neural network can approximate any continuous function to any degree of accuracy, by using either an arbitrary squashing function or any continuous sigmoidal function for activation. Making use of the Stone-Weirstrass Theorem again, we extend these approximation capabilities of multilayer feedforward artificial neural networks to the space of measurable functions under any probability measure.
- Full Text:
- Date Issued: 2011
Using information visualization techniques to support web service discovery
- Authors: Beets, Simone
- Date: 2011
- Subjects: Information visualization , Web services , Information visualization -- Computer programs
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10457 , http://hdl.handle.net/10948/1659 , Information visualization , Web services , Information visualization -- Computer programs
- Description: The increasing number of web services published over the Web highlights the need for an effective method for users to find appropriate web services. Existing web service discovery methods do not effectively aid a user in finding suitable web services. The current methods provide textual lists of web services that the user is required to explore and manually evaluate. Thus, these methods lead to time-consuming and ineffective web service discovery. The aim of this research was to investigate using information visualization (IV) techniques to effectively support web service discovery. The node-and-link network IV technique was selected as the most appropriate IV technique to visualize web service collections. A prototype, called SerViz, was developed as a tool for interactive visualization of web service collections incorporating the node-and-link IV technique and an alphabetical list-based technique. SerViz used the Programmable Web web service collection as the sample web service collection. A usability evaluation was conducted to compare these techniques. Ninety percent of participants preferred the network IV technique for visualizing web service collections. The network IV technique was also faster for browsing. Several usability problems were identified with the network IV technique. This motivated a need for implementing an alternative IV technique in SerViz. The node-and-link tree IV technique was selected as it was more structured than the network IV technique. A usability evaluation was conducted to compare the network and tree IV techniques. Participants slightly preferred the tree IV technique as the technique to visualize web service collections. The tree IV technique was faster for browsing the web service collection while the network IV technique was faster for searching and filtering. This research has determined that IV techniques can be used to effectively support web service discovery. Future work will involve using IV techniques to support collaborative web service discovery. Keywords: Web Service Discovery, Information Visualization, Web Service Collections, Information Visualization Techniques.
- Full Text:
- Date Issued: 2011
- Authors: Beets, Simone
- Date: 2011
- Subjects: Information visualization , Web services , Information visualization -- Computer programs
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10457 , http://hdl.handle.net/10948/1659 , Information visualization , Web services , Information visualization -- Computer programs
- Description: The increasing number of web services published over the Web highlights the need for an effective method for users to find appropriate web services. Existing web service discovery methods do not effectively aid a user in finding suitable web services. The current methods provide textual lists of web services that the user is required to explore and manually evaluate. Thus, these methods lead to time-consuming and ineffective web service discovery. The aim of this research was to investigate using information visualization (IV) techniques to effectively support web service discovery. The node-and-link network IV technique was selected as the most appropriate IV technique to visualize web service collections. A prototype, called SerViz, was developed as a tool for interactive visualization of web service collections incorporating the node-and-link IV technique and an alphabetical list-based technique. SerViz used the Programmable Web web service collection as the sample web service collection. A usability evaluation was conducted to compare these techniques. Ninety percent of participants preferred the network IV technique for visualizing web service collections. The network IV technique was also faster for browsing. Several usability problems were identified with the network IV technique. This motivated a need for implementing an alternative IV technique in SerViz. The node-and-link tree IV technique was selected as it was more structured than the network IV technique. A usability evaluation was conducted to compare the network and tree IV techniques. Participants slightly preferred the tree IV technique as the technique to visualize web service collections. The tree IV technique was faster for browsing the web service collection while the network IV technique was faster for searching and filtering. This research has determined that IV techniques can be used to effectively support web service discovery. Future work will involve using IV techniques to support collaborative web service discovery. Keywords: Web Service Discovery, Information Visualization, Web Service Collections, Information Visualization Techniques.
- Full Text:
- Date Issued: 2011
Using multi-touch interaction techniques to support Collaborative Information Retrieval
- Authors: Sams, Ivan
- Date: 2011
- Subjects: Human-computer interaction , Teams in the workplace -- Data processing , Groupware (Computer software) , Interactive computer systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10491 , http://hdl.handle.net/10948/d1020156
- Description: Collaborative Information Retrieval (CIR) is a branch of Computer Supported Cooperative Work (CSCW). CIR is the process by which people search for and retrieve information, working together and using documents as data sources. Currently, computer support for CIR is limited to single user systems. Collaboration takes place either with users working at different times or in different locations. Multi-touch interaction has recently seen a rise in prominence owing to a reduction in the cost of the technology and increased frequency of use. Multi-touch surface computing allows multiple users to interact at once around a shared display. The aim of this research was to investigate how multi-touch interaction techniques could be used to support CIR effectively in a co-located environment. An application architecture for CIR systems that incorporates multi-touch interaction techniques was proposed. A prototype, called Co-IMBRA, was developed based on this architecture that used multi-touch interaction techniques to support CIR. This prototype allows multiple users to retrieve information, using the Internet as a shared information space. Documents are represented as visual objects that can be manipulated on the multi-touch surface, as well as rated, annotated and added to folders. A user study was undertaken to evaluate Co-IMBRA and determine whether the multi-touch interaction techniques effectively supported CIR. Fifteen teams of two users each participated in the user study. High task completion rates and low task times showed that the system was effective and efficient. High levels of user satisfaction were reported in the post-test questionnaires. Participants rated the system as highly useful and several commented that it promoted collaboration and that they enjoyed the test. The successful implementation of Co-IMBRA provides evidence that multi-touch interaction techniques can effectively support CIR. The results of the user evaluation also enabled recommendations for future research to be made.
- Full Text:
- Date Issued: 2011
- Authors: Sams, Ivan
- Date: 2011
- Subjects: Human-computer interaction , Teams in the workplace -- Data processing , Groupware (Computer software) , Interactive computer systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10491 , http://hdl.handle.net/10948/d1020156
- Description: Collaborative Information Retrieval (CIR) is a branch of Computer Supported Cooperative Work (CSCW). CIR is the process by which people search for and retrieve information, working together and using documents as data sources. Currently, computer support for CIR is limited to single user systems. Collaboration takes place either with users working at different times or in different locations. Multi-touch interaction has recently seen a rise in prominence owing to a reduction in the cost of the technology and increased frequency of use. Multi-touch surface computing allows multiple users to interact at once around a shared display. The aim of this research was to investigate how multi-touch interaction techniques could be used to support CIR effectively in a co-located environment. An application architecture for CIR systems that incorporates multi-touch interaction techniques was proposed. A prototype, called Co-IMBRA, was developed based on this architecture that used multi-touch interaction techniques to support CIR. This prototype allows multiple users to retrieve information, using the Internet as a shared information space. Documents are represented as visual objects that can be manipulated on the multi-touch surface, as well as rated, annotated and added to folders. A user study was undertaken to evaluate Co-IMBRA and determine whether the multi-touch interaction techniques effectively supported CIR. Fifteen teams of two users each participated in the user study. High task completion rates and low task times showed that the system was effective and efficient. High levels of user satisfaction were reported in the post-test questionnaires. Participants rated the system as highly useful and several commented that it promoted collaboration and that they enjoyed the test. The successful implementation of Co-IMBRA provides evidence that multi-touch interaction techniques can effectively support CIR. The results of the user evaluation also enabled recommendations for future research to be made.
- Full Text:
- Date Issued: 2011