In vitro dissolution kinetics of Captopril from microspheres manufactured by solvent evaporation
- Khamanga, Sandile M, Walker, Roderick B
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6390 , http://hdl.handle.net/10962/d1006311
- Description: The aim of this study was to develop and assess captopril-loaded microspheres in which Methocel and Eudragit RS were used as release-controlling factors and to evaluate captopril (CPT) release using kinetic models. Drug-excipient interactions were evaluated using infrared studies, and the physical appearance was characterized using scanning electron microscopy (SEM). A burst effect was observed during the first stage of dissolution for most batches of microspheres. SEM results reveal that this may be attributed to dissolution of captopril crystals that were present on the surface, embedded in the superficial layer of the matrix materials, trapped near the surface of the microspheres, or that may have diffused rapidly through the porous surface of the capsules. The release data generated during in vitro release studies were fitted to zero-order, first-order, Higuchi, Korsmeyer–Peppas, Kopcha, and Makoid–Banakar models. The release kinetics of captopril from most formulations followed a classical Fickian diffusion mechanism. SEM photographs showed that diffusion took place through pores located in the surface of the microcapsules. The Kopcha model diffusion and erosion terms showed a predominance of diffusion relative to swelling or erosion throughout the entire test period. The drug release mechanism was also confirmed by the Makoid–Banakar and Korsmeyer–Peppas model exponents. This further supports a diffusion–release mechanism for most formulations. The models postulate that the total drug released is a summation of several mechanisms (viz., burst release, relaxation-induced controlled release, and diffusional release). These results also support the potential application of Eudragit/Methocel microspheres as a suitable sustained-release drug delivery system for captopril.
- Full Text:
- Date Issued: 2012
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6390 , http://hdl.handle.net/10962/d1006311
- Description: The aim of this study was to develop and assess captopril-loaded microspheres in which Methocel and Eudragit RS were used as release-controlling factors and to evaluate captopril (CPT) release using kinetic models. Drug-excipient interactions were evaluated using infrared studies, and the physical appearance was characterized using scanning electron microscopy (SEM). A burst effect was observed during the first stage of dissolution for most batches of microspheres. SEM results reveal that this may be attributed to dissolution of captopril crystals that were present on the surface, embedded in the superficial layer of the matrix materials, trapped near the surface of the microspheres, or that may have diffused rapidly through the porous surface of the capsules. The release data generated during in vitro release studies were fitted to zero-order, first-order, Higuchi, Korsmeyer–Peppas, Kopcha, and Makoid–Banakar models. The release kinetics of captopril from most formulations followed a classical Fickian diffusion mechanism. SEM photographs showed that diffusion took place through pores located in the surface of the microcapsules. The Kopcha model diffusion and erosion terms showed a predominance of diffusion relative to swelling or erosion throughout the entire test period. The drug release mechanism was also confirmed by the Makoid–Banakar and Korsmeyer–Peppas model exponents. This further supports a diffusion–release mechanism for most formulations. The models postulate that the total drug released is a summation of several mechanisms (viz., burst release, relaxation-induced controlled release, and diffusional release). These results also support the potential application of Eudragit/Methocel microspheres as a suitable sustained-release drug delivery system for captopril.
- Full Text:
- Date Issued: 2012
In vitro photodynamic effect of aluminum tetrasulfophthalocyanines on melanoma skin cancer and healthy normal skin cells
- Maduray, Kaminee, Odhay, Bharti, Nyokong, Tebello
- Authors: Maduray, Kaminee , Odhay, Bharti , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245762 , vital:51403 , xlink:href="https://doi.org/10.1016/j.pdpdt.2011.07.001"
- Description: Photodynamic therapy is a medical treatment that uses an inactive dye/drug and lasers as a light source to activate the dye/drug to produce a toxic form of oxygen that destroys the cancer cells. This study aimed at investigating the cytotoxic effects of different concentrations of aluminum tetrasulfophthalocyanines in its inactive and active state (laser induced) on melanoma skin cancer cells, healthy normal skin fibroblast and keratinocyte cells. Experimentally, 3 x 10(4) cells/ml were seeded in 24-well plates before treatment with different concentrations of aluminum tetrasulfophthalocyanines. After 2 h, cells were irradiated with a light dose of 4.5 J/cm(2). Post-irradiated cells were incubated for 24 h before cell viability was measured using the CellTiter-Blue Viability Assay. Results showed that aluminum tetrasulfophthalocyanines at high concentrations were cytotoxic to melanoma cells in the absence of laser activation. In the presence of laser activation of aluminum tetrasulfophthalocyanines at a concentration of 40 mu g/ml decreased cell viability of melanoma cells to 45%, fibroblasts to 78% and keratinocytes to 73%. At this photosensitizing concentration of aluminum tetrasulfophthalocyanines the efficacy of the treatment light dose 4.5 J/cm(2) and the cell death mechanism induced by photoactivated aluminum tetrasulfophthalocyanines was evaluated. A light dose of 4.5 J/cm(2) was more efficient in killing a higher number of melanoma cells and a lower number of fibroblast and keratinocyte cells than the other light doses of 2.5 J/cm(2), 7.5 J/cm(2) and 10.5 J/cm(2). Apoptosis features such as blebbing, nucleus condensation, nucleus fragmentation and the formation of apoptotic bodies were seen in the photodynamic therapy treated melanoma skin cancer cells. This in vitro photodynamic therapy study concludes that using aluminum tetrasulfophthalocyanines at a photosensitizing concentration of 40 mu g/ml in combination with a laser dose of 4.5 J/cm(2) was potentially lethal for melanoma skin cancer cells and less harmful for the normal healthy skin cells. (c) 2011 Elsevier B.V. All rights reserved.
- Full Text:
- Date Issued: 2012
- Authors: Maduray, Kaminee , Odhay, Bharti , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245762 , vital:51403 , xlink:href="https://doi.org/10.1016/j.pdpdt.2011.07.001"
- Description: Photodynamic therapy is a medical treatment that uses an inactive dye/drug and lasers as a light source to activate the dye/drug to produce a toxic form of oxygen that destroys the cancer cells. This study aimed at investigating the cytotoxic effects of different concentrations of aluminum tetrasulfophthalocyanines in its inactive and active state (laser induced) on melanoma skin cancer cells, healthy normal skin fibroblast and keratinocyte cells. Experimentally, 3 x 10(4) cells/ml were seeded in 24-well plates before treatment with different concentrations of aluminum tetrasulfophthalocyanines. After 2 h, cells were irradiated with a light dose of 4.5 J/cm(2). Post-irradiated cells were incubated for 24 h before cell viability was measured using the CellTiter-Blue Viability Assay. Results showed that aluminum tetrasulfophthalocyanines at high concentrations were cytotoxic to melanoma cells in the absence of laser activation. In the presence of laser activation of aluminum tetrasulfophthalocyanines at a concentration of 40 mu g/ml decreased cell viability of melanoma cells to 45%, fibroblasts to 78% and keratinocytes to 73%. At this photosensitizing concentration of aluminum tetrasulfophthalocyanines the efficacy of the treatment light dose 4.5 J/cm(2) and the cell death mechanism induced by photoactivated aluminum tetrasulfophthalocyanines was evaluated. A light dose of 4.5 J/cm(2) was more efficient in killing a higher number of melanoma cells and a lower number of fibroblast and keratinocyte cells than the other light doses of 2.5 J/cm(2), 7.5 J/cm(2) and 10.5 J/cm(2). Apoptosis features such as blebbing, nucleus condensation, nucleus fragmentation and the formation of apoptotic bodies were seen in the photodynamic therapy treated melanoma skin cancer cells. This in vitro photodynamic therapy study concludes that using aluminum tetrasulfophthalocyanines at a photosensitizing concentration of 40 mu g/ml in combination with a laser dose of 4.5 J/cm(2) was potentially lethal for melanoma skin cancer cells and less harmful for the normal healthy skin cells. (c) 2011 Elsevier B.V. All rights reserved.
- Full Text:
- Date Issued: 2012
In-beam spectroscopy of ⁷²Ge
- Authors: Henninger, Katharine Rose
- Date: 2012
- Subjects: Nuclear shapes , Hyperfine structure
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5559 , http://hdl.handle.net/10962/d1018233
- Description: The high-spin states of the nucleus ⁷²Ge were populated via the ⁷°Zn(a,2n)⁷²Ge fusion-evaporation reaction at a beam-energy of 30 MeV. The ')'-decays were observed with the AFRODITE spectrometer array at iThemba LABS (Faure, South Africa). Twenty-seven new transitions, 18 new levels and 2 new bands were added to the ⁷²Ge level scheme, and several corrections were made to t he previously-known level scheme. Transitions were characterised using Directional Correlation from Oriented states (DCO) and polarisation measurements, and spin-parity assignments were made for 7 new levels. Spin and parity were also reassigned to a previously-known structure. One of the new bands was ident ified as part of an octupole-vibrational band. No tetrahedral states were observed in the scheme despite N = 40 and Z = 32 having been identified as tetrahedral magic numbers. The meaning of the new 14⁺ yrast level for the underlying structure of the ground state band is discussed
- Full Text:
- Date Issued: 2012
- Authors: Henninger, Katharine Rose
- Date: 2012
- Subjects: Nuclear shapes , Hyperfine structure
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5559 , http://hdl.handle.net/10962/d1018233
- Description: The high-spin states of the nucleus ⁷²Ge were populated via the ⁷°Zn(a,2n)⁷²Ge fusion-evaporation reaction at a beam-energy of 30 MeV. The ')'-decays were observed with the AFRODITE spectrometer array at iThemba LABS (Faure, South Africa). Twenty-seven new transitions, 18 new levels and 2 new bands were added to the ⁷²Ge level scheme, and several corrections were made to t he previously-known level scheme. Transitions were characterised using Directional Correlation from Oriented states (DCO) and polarisation measurements, and spin-parity assignments were made for 7 new levels. Spin and parity were also reassigned to a previously-known structure. One of the new bands was ident ified as part of an octupole-vibrational band. No tetrahedral states were observed in the scheme despite N = 40 and Z = 32 having been identified as tetrahedral magic numbers. The meaning of the new 14⁺ yrast level for the underlying structure of the ground state band is discussed
- Full Text:
- Date Issued: 2012
Inclusive education: a phenomenological study of the experiences of teachers in a mainstream primary school in East London
- Authors: Naidoo, Allan Quinton
- Date: 2012
- Language: English
- Type: Thesis , Masters , M Ed
- Identifier: vital:16179 , http://hdl.handle.net/10353/531
- Description: In 2001 the Department of Education formulated policy that makes provision for learners with mild to moderate barriers to learning to be taught in mainstream primary schools. This policy became known as White Paper 6: Special needs education. The premise of this policy is to eventually convert all mainstream primary schools into full service schools that will cater for the full range of educational needs. The policy however created a dilemma for mainstream primary schools as the majority of them never received any training in special needs education. Most teachers therefore do not have the required knowledge and skills to adapt the national curriculum (NCS) and assessment methods so that it will accommodate the learning needs of all learners. Teachers thus experience the policy regulations as complex. This is a phenomenological study located within the interpretive research paradigm. Qualitative research methods namely phenomenological interviews were employed to gather data that could expound on and give an in-depth understanding of the experiences of teachers who are confronted with a diversity of educational needs. The investigation took place at a mainstream primary school that has a substantial history of catering to the educational needs of learners who experience problems with their learning and addressing physical disabilities such as hearing problems, autism and ADHD. The fact that the study focused only on one school served as a major limitation. The findings of the study can therefore not be generalized to other educational settings. WP6 is however national policy therefore the findings of the study could be valuable for gaining understanding of the intricacies of inclusive education. The data revealed that teachers are finding it difficult to implement inclusive education. This complexity is caused by a myriad of factors which impact negatively on the experiences of teachers such as high learner numbers, diversity of learning abilities and styles, a heavy workload, behavioural problems, language problems, challenges related to the curriculum and assessment and inefficient support services. However, despite lacking the prerequisite knowledge and skills for effective inclusive education, teachers tried their utmost to reach all the learners.
- Full Text:
- Date Issued: 2012
- Authors: Naidoo, Allan Quinton
- Date: 2012
- Language: English
- Type: Thesis , Masters , M Ed
- Identifier: vital:16179 , http://hdl.handle.net/10353/531
- Description: In 2001 the Department of Education formulated policy that makes provision for learners with mild to moderate barriers to learning to be taught in mainstream primary schools. This policy became known as White Paper 6: Special needs education. The premise of this policy is to eventually convert all mainstream primary schools into full service schools that will cater for the full range of educational needs. The policy however created a dilemma for mainstream primary schools as the majority of them never received any training in special needs education. Most teachers therefore do not have the required knowledge and skills to adapt the national curriculum (NCS) and assessment methods so that it will accommodate the learning needs of all learners. Teachers thus experience the policy regulations as complex. This is a phenomenological study located within the interpretive research paradigm. Qualitative research methods namely phenomenological interviews were employed to gather data that could expound on and give an in-depth understanding of the experiences of teachers who are confronted with a diversity of educational needs. The investigation took place at a mainstream primary school that has a substantial history of catering to the educational needs of learners who experience problems with their learning and addressing physical disabilities such as hearing problems, autism and ADHD. The fact that the study focused only on one school served as a major limitation. The findings of the study can therefore not be generalized to other educational settings. WP6 is however national policy therefore the findings of the study could be valuable for gaining understanding of the intricacies of inclusive education. The data revealed that teachers are finding it difficult to implement inclusive education. This complexity is caused by a myriad of factors which impact negatively on the experiences of teachers such as high learner numbers, diversity of learning abilities and styles, a heavy workload, behavioural problems, language problems, challenges related to the curriculum and assessment and inefficient support services. However, despite lacking the prerequisite knowledge and skills for effective inclusive education, teachers tried their utmost to reach all the learners.
- Full Text:
- Date Issued: 2012
Incorporating prey demographics and predator social structure into prey selection and carrying capacity estimates for cheetah
- Authors: Clements, Hayley Susan
- Date: 2012
- Subjects: Carnivorous animals , Cheetah
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10754 , http://hdl.handle.net/10948/d1018606
- Description: There is a need for a refined understanding of large carnivore prey preference and carrying capacity (K). To date, K estimates for large carnivores have been developed from predictions of carnivore diet at a prey and predator species-level. These predictions therefore assume that all social classes within a carnivore species display similar prey preferences and that all demographic classes within a prey species are equally preferred or avoided. The objective of this study was to investigate the importance of including prey demographics and carnivore social class in carnivore diet descriptions and thereby K estimates, using cheetah Acinonyx jubatus as a study species. It was predicted that prey sex, prey age and cheetah social class influence cheetah prey preferences, when they influence the risk and ease of prey capture, and that their inclusion in a K model would improve its predictive strength. Based on an analysis of 1290 kills from South Africa, male coalition cheetah were found to prefer a broader weight range of prey than solitary cheetah. Prey demographics further influenced cheetah prey preference, when it corresponded to differences in prey size and the presence of horns. The current species-level K regression model for cheetah is based on preferred prey and thus omits highly abundant antelope that often comprise the majority of the diet, an artefact of the way in which preferences are calculated. A refinement of the species-level K regression model, to account for prey demographic- and cheetah social class-level differences in diet and the biomass of accessible prey (defined in this study as all non-avoided prey) instead of just preferred prey, doubled the predictive strength of the K model. Because group-hunting enabled predation on a broader weight range of prey, cheetah K was influenced by the ratio of male coalition cheetah to solitary cheetah in the population. The refined K regression model is derived from ecosystems supporting an intact carnivore guild. A mechanistic approach to estimating K, based on Caughley‟s (1977) maximum sustainable yield model, therefore better predicted cheetah K in systems devoid of lion Panthera leo and African wild dog Lycaon pictus, which were found to suppress cheetah density. This study improves our understanding of the relationships between prey demographics, cheetah social classes and intra-guild competition in determining cheetah prey preferences and K. This study therefore paves the way for similar work on other large carnivores.
- Full Text:
- Date Issued: 2012
- Authors: Clements, Hayley Susan
- Date: 2012
- Subjects: Carnivorous animals , Cheetah
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10754 , http://hdl.handle.net/10948/d1018606
- Description: There is a need for a refined understanding of large carnivore prey preference and carrying capacity (K). To date, K estimates for large carnivores have been developed from predictions of carnivore diet at a prey and predator species-level. These predictions therefore assume that all social classes within a carnivore species display similar prey preferences and that all demographic classes within a prey species are equally preferred or avoided. The objective of this study was to investigate the importance of including prey demographics and carnivore social class in carnivore diet descriptions and thereby K estimates, using cheetah Acinonyx jubatus as a study species. It was predicted that prey sex, prey age and cheetah social class influence cheetah prey preferences, when they influence the risk and ease of prey capture, and that their inclusion in a K model would improve its predictive strength. Based on an analysis of 1290 kills from South Africa, male coalition cheetah were found to prefer a broader weight range of prey than solitary cheetah. Prey demographics further influenced cheetah prey preference, when it corresponded to differences in prey size and the presence of horns. The current species-level K regression model for cheetah is based on preferred prey and thus omits highly abundant antelope that often comprise the majority of the diet, an artefact of the way in which preferences are calculated. A refinement of the species-level K regression model, to account for prey demographic- and cheetah social class-level differences in diet and the biomass of accessible prey (defined in this study as all non-avoided prey) instead of just preferred prey, doubled the predictive strength of the K model. Because group-hunting enabled predation on a broader weight range of prey, cheetah K was influenced by the ratio of male coalition cheetah to solitary cheetah in the population. The refined K regression model is derived from ecosystems supporting an intact carnivore guild. A mechanistic approach to estimating K, based on Caughley‟s (1977) maximum sustainable yield model, therefore better predicted cheetah K in systems devoid of lion Panthera leo and African wild dog Lycaon pictus, which were found to suppress cheetah density. This study improves our understanding of the relationships between prey demographics, cheetah social classes and intra-guild competition in determining cheetah prey preferences and K. This study therefore paves the way for similar work on other large carnivores.
- Full Text:
- Date Issued: 2012
Increasing the gap tolerance in friction stir welded joints of AA6082-T6
- Authors: Oyedemi, Kayode
- Date: 2012
- Subjects: Friction stir welding , Aluminum alloys -- Welding , Welding
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9628 , http://hdl.handle.net/10948/d1012325 , Friction stir welding , Aluminum alloys -- Welding , Welding
- Description: This research project was conducted to increase weld gap tolerance in Friction Stir Welding (FSW) of 8 mm thick aluminum alloy 6082 – T6. Investigation was done on I-STIR PDS platform and a Johnford milling machine. The research project involved tool-pin design with varying re-entrant features and varying parameters as a method of weld gap closing to produce successful welds. Direction of spindle rotation and dwell time were established as part of a preliminary study. Clockwise spindle rotation with 20 seconds dwell time allows sufficient plasticity and improved material flow which assisted in achieving welds with prior 30 percent weld gap of the plate thickness. Final welds were made using three rotational speeds and feed rates with sufficient plunging to prevent root defects. Analysis of the results were detailed which include vickers microhardness test, tensile test and metallographic observation to access the suitability of the weld structure. From the set of tool-pins designed, the flare tool-pin gave a well-defined weld nugget with improved stirring at the weld root. Also, with a concave shoulder, right hand threaded tool-pin and counterclockwise flutes undergoing a clockwise spindle rotation, plasticized material flow was upward which was beneficial in reducing the amount of plate thinning. The right hand thread counter clockwise flute with a flute machined in the foot exhibited superior tensile strength for welds containing 30 percent weld gap.
- Full Text:
- Date Issued: 2012
- Authors: Oyedemi, Kayode
- Date: 2012
- Subjects: Friction stir welding , Aluminum alloys -- Welding , Welding
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9628 , http://hdl.handle.net/10948/d1012325 , Friction stir welding , Aluminum alloys -- Welding , Welding
- Description: This research project was conducted to increase weld gap tolerance in Friction Stir Welding (FSW) of 8 mm thick aluminum alloy 6082 – T6. Investigation was done on I-STIR PDS platform and a Johnford milling machine. The research project involved tool-pin design with varying re-entrant features and varying parameters as a method of weld gap closing to produce successful welds. Direction of spindle rotation and dwell time were established as part of a preliminary study. Clockwise spindle rotation with 20 seconds dwell time allows sufficient plasticity and improved material flow which assisted in achieving welds with prior 30 percent weld gap of the plate thickness. Final welds were made using three rotational speeds and feed rates with sufficient plunging to prevent root defects. Analysis of the results were detailed which include vickers microhardness test, tensile test and metallographic observation to access the suitability of the weld structure. From the set of tool-pins designed, the flare tool-pin gave a well-defined weld nugget with improved stirring at the weld root. Also, with a concave shoulder, right hand threaded tool-pin and counterclockwise flutes undergoing a clockwise spindle rotation, plasticized material flow was upward which was beneficial in reducing the amount of plate thinning. The right hand thread counter clockwise flute with a flute machined in the foot exhibited superior tensile strength for welds containing 30 percent weld gap.
- Full Text:
- Date Issued: 2012
Inferring direct DNA binding from ChIP-seq
- Bailey, Timothy L, Machanick, Philip
- Authors: Bailey, Timothy L , Machanick, Philip
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439314 , vital:73565 , https://doi.org/10.1093/nar/gks433
- Description: Genome-wide binding data from transcription factor ChIP-seq experiments is the best source of information for inferring the relative DNA-binding affinity of these proteins in vivo . However, standard motif enrichment analysis and motif discovery approaches sometimes fail to correctly identify the binding motif for the ChIP-ed factor. To overcome this problem, we propose ‘central motif enrichment analysis’ (CMEA), which is based on the observation that the positional distribution of binding sites matching the direct-binding motif tends to be unimodal, well centered and maximal in the precise center of the ChIP-seq peak regions. We describe a novel visualization and statistical analysis tool—CentriMo—that identifies the region of maximum central enrichment in a set of ChIP-seq peak regions and displays the positional distributions of predicted sites. Using CentriMo for motif enrichment analysis, we provide evidence that one transcription factor (Nanog) has different binding affinity in vivo than in vitro , that another binds DNA cooperatively (E2f1), and confirm the in vivo affinity of NFIC, rescuing a difficult ChIP-seq data set. In another data set, CentriMo strongly suggests that there is no evidence of direct DNA binding by the ChIP-ed factor (Smad1). CentriMo is now part of the MEME Suite software package available at http://meme.nbcr.net . All data and output files presented here are available at: http://research.imb.uq.edu.au/t.bailey/sd/Bailey2011a .
- Full Text:
- Date Issued: 2012
- Authors: Bailey, Timothy L , Machanick, Philip
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439314 , vital:73565 , https://doi.org/10.1093/nar/gks433
- Description: Genome-wide binding data from transcription factor ChIP-seq experiments is the best source of information for inferring the relative DNA-binding affinity of these proteins in vivo . However, standard motif enrichment analysis and motif discovery approaches sometimes fail to correctly identify the binding motif for the ChIP-ed factor. To overcome this problem, we propose ‘central motif enrichment analysis’ (CMEA), which is based on the observation that the positional distribution of binding sites matching the direct-binding motif tends to be unimodal, well centered and maximal in the precise center of the ChIP-seq peak regions. We describe a novel visualization and statistical analysis tool—CentriMo—that identifies the region of maximum central enrichment in a set of ChIP-seq peak regions and displays the positional distributions of predicted sites. Using CentriMo for motif enrichment analysis, we provide evidence that one transcription factor (Nanog) has different binding affinity in vivo than in vitro , that another binds DNA cooperatively (E2f1), and confirm the in vivo affinity of NFIC, rescuing a difficult ChIP-seq data set. In another data set, CentriMo strongly suggests that there is no evidence of direct DNA binding by the ChIP-ed factor (Smad1). CentriMo is now part of the MEME Suite software package available at http://meme.nbcr.net . All data and output files presented here are available at: http://research.imb.uq.edu.au/t.bailey/sd/Bailey2011a .
- Full Text:
- Date Issued: 2012
Inflation targeting and inflation indicators: the case for inflation targeting in South Africa
- Authors: Jeke, Leward
- Date: 2012
- Subjects: South African Reserve Bank , Inflation (Finance) -- South Africa , Inflation targeting -- South Africa , Anti-inflationary policies -- South Africa , Economic indicators -- South Africa , Economic stabilization -- South Africa , Cointegration -- South Africa
- Language: English
- Type: Thesis , Masters , M Com
- Identifier: vital:11467 , http://hdl.handle.net/10353/d1007091 , South African Reserve Bank , Inflation (Finance) -- South Africa , Inflation targeting -- South Africa , Anti-inflationary policies -- South Africa , Economic indicators -- South Africa , Economic stabilization -- South Africa , Cointegration -- South Africa
- Description: The control of inflation requires a forecast of the future path of the price level and its indicators. Targeting inflation directly requires that the central bank (SARB) form forecasts of the likely path of prices paying close attention to a variety of indicators that shows the predictive power of inflation in the past periods. Inflation indicators might be cointegrated with the rate of inflation to predict the future inflation rates. Forecasting inflation may be very difficult at a particular period due to the fact that the array candidate indicators of inflation may neither be very stable nor very strong in their relationships with the rate of inflation. Although this might be the case, this research uses testable effects of each of the South African inflation indicators to the rate of inflation using econometrics tools to find that they have a long run trend with the rate of inflation in South Africa. It has been found that each of the indicator variables has a long run relationship with the rate of inflation. The major conclusion is that inflation indicator variables like money supply (M3), oil price, gold price, total employment, interest rates, exchange rates and output growth can be useful inflation indicators in targeting the future trends of inflation in South Africa according to the data used in this research although some studies in some countries find that inflation targeting is an insufficient framework for monetary policy in the presence of financial exuberance. The money supply, the oil prices, interest rates, the exchange rates, prices of gold, the employment and output growth are co-integrated with the rate of inflation representing a long-run relationship.
- Full Text:
- Date Issued: 2012
- Authors: Jeke, Leward
- Date: 2012
- Subjects: South African Reserve Bank , Inflation (Finance) -- South Africa , Inflation targeting -- South Africa , Anti-inflationary policies -- South Africa , Economic indicators -- South Africa , Economic stabilization -- South Africa , Cointegration -- South Africa
- Language: English
- Type: Thesis , Masters , M Com
- Identifier: vital:11467 , http://hdl.handle.net/10353/d1007091 , South African Reserve Bank , Inflation (Finance) -- South Africa , Inflation targeting -- South Africa , Anti-inflationary policies -- South Africa , Economic indicators -- South Africa , Economic stabilization -- South Africa , Cointegration -- South Africa
- Description: The control of inflation requires a forecast of the future path of the price level and its indicators. Targeting inflation directly requires that the central bank (SARB) form forecasts of the likely path of prices paying close attention to a variety of indicators that shows the predictive power of inflation in the past periods. Inflation indicators might be cointegrated with the rate of inflation to predict the future inflation rates. Forecasting inflation may be very difficult at a particular period due to the fact that the array candidate indicators of inflation may neither be very stable nor very strong in their relationships with the rate of inflation. Although this might be the case, this research uses testable effects of each of the South African inflation indicators to the rate of inflation using econometrics tools to find that they have a long run trend with the rate of inflation in South Africa. It has been found that each of the indicator variables has a long run relationship with the rate of inflation. The major conclusion is that inflation indicator variables like money supply (M3), oil price, gold price, total employment, interest rates, exchange rates and output growth can be useful inflation indicators in targeting the future trends of inflation in South Africa according to the data used in this research although some studies in some countries find that inflation targeting is an insufficient framework for monetary policy in the presence of financial exuberance. The money supply, the oil prices, interest rates, the exchange rates, prices of gold, the employment and output growth are co-integrated with the rate of inflation representing a long-run relationship.
- Full Text:
- Date Issued: 2012
Influence of distance from the target on total response time, repeated punch force and anaerobic fatigue of amateur boxers
- Authors: Trella, Christopher
- Date: 2012
- Subjects: Boxing -- Training , Sports performance
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:10106 , http://hdl.handle.net/10948/d1020024
- Description: The aim of this study was to determine the influence of distance from the target during dominant and non-dominant jab punches, on total response time, repeated jab punch force and anaerobic fatigue of amateur boxers. Data was gathered of the following variables: Biographical data, anthropometric data, total response time, change in total response time, number of punches, peak punch force and peak punch force fatigue resistance index. An exploratory and descriptive research design was used. Twelve male amateur boxers participated in this study. The participants were all either provincially or nationally ranked, between the ages 16 and 22 and in the competitive phase of their training. The data was compared to find statistical significance and it was found from the Wilcoxon ranked sign test that distance does not affect total response time, change in total response time, number of punches and peak punch force fatigue resistance index. However, it was found that distance affects peak punch force. Additionally,it was found using a Spearman rank correlation test that older boxers proved to have statistically significant faster total response times, the boxers that had slower total reponse times proved to have statistically significant less powerful peak punch force, the boxers that had slower total response times proved to have statistically significant larger fatigue resistance index, boxers with larger change in total response time proved to have statistically significant more powerful peak punch force and the boxers with larger peak punch force proved to have statistically significant smaller fatigue resistance index. The data presented provides an introduction of the exploration of how distance from a target relates to a boxer’s performance.
- Full Text:
- Date Issued: 2012
- Authors: Trella, Christopher
- Date: 2012
- Subjects: Boxing -- Training , Sports performance
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:10106 , http://hdl.handle.net/10948/d1020024
- Description: The aim of this study was to determine the influence of distance from the target during dominant and non-dominant jab punches, on total response time, repeated jab punch force and anaerobic fatigue of amateur boxers. Data was gathered of the following variables: Biographical data, anthropometric data, total response time, change in total response time, number of punches, peak punch force and peak punch force fatigue resistance index. An exploratory and descriptive research design was used. Twelve male amateur boxers participated in this study. The participants were all either provincially or nationally ranked, between the ages 16 and 22 and in the competitive phase of their training. The data was compared to find statistical significance and it was found from the Wilcoxon ranked sign test that distance does not affect total response time, change in total response time, number of punches and peak punch force fatigue resistance index. However, it was found that distance affects peak punch force. Additionally,it was found using a Spearman rank correlation test that older boxers proved to have statistically significant faster total response times, the boxers that had slower total reponse times proved to have statistically significant less powerful peak punch force, the boxers that had slower total response times proved to have statistically significant larger fatigue resistance index, boxers with larger change in total response time proved to have statistically significant more powerful peak punch force and the boxers with larger peak punch force proved to have statistically significant smaller fatigue resistance index. The data presented provides an introduction of the exploration of how distance from a target relates to a boxer’s performance.
- Full Text:
- Date Issued: 2012
Influence of distance from the target on total response time, repeated punch force and anaerobic fatigue of amatuer boxers
- Authors: Trella, Christopher Andrew
- Date: 2012
- Subjects: Boxers (Sports) , Physical education and training
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:10111 , http://hdl.handle.net/10948/d1020942
- Description: The aim of this study was to determine the influence of distance from the target during dominant and non-dominant jab punches, on total response time, repeated jab punch force and anaerobic fatigue of amateur boxers. Data was gathered of the following variables: Biographical data, anthropometric data, total response time, change in total response time, number of punches, peak punch force and peak punch force fatigue resistance index. An exploratory and descriptive research design was used. Twelve male amateur boxers participated in this study. The participants were all either provincially or nationally ranked, between the ages 16 and 22 and in the competitive phase of their training. The data was compared to find statistical significance and it was found from the Wilcoxon ranked sign test that distance does not affect total response time, change in total response time, number of punches and peak punch force fatigue resistance index. However, it was found that distance affects peak punch force. Additionally,it was found using a Spearman rank correlation test that older boxers proved to have statistically significant faster total response times, the boxers that had slower total reponse times proved to have statistically significant less powerful peak punch force, the boxers that had slower total response times proved to have statistically significant larger fatigue resistance index, boxers with larger change in total response time proved to have statistically significant more powerful peak punch force and the boxers with larger peak punch force proved to have statistically significant smaller fatigue resistance index. The data presented provides an introduction of the exploration of how distance from a target relates to a boxer’s performance.
- Full Text:
- Date Issued: 2012
- Authors: Trella, Christopher Andrew
- Date: 2012
- Subjects: Boxers (Sports) , Physical education and training
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:10111 , http://hdl.handle.net/10948/d1020942
- Description: The aim of this study was to determine the influence of distance from the target during dominant and non-dominant jab punches, on total response time, repeated jab punch force and anaerobic fatigue of amateur boxers. Data was gathered of the following variables: Biographical data, anthropometric data, total response time, change in total response time, number of punches, peak punch force and peak punch force fatigue resistance index. An exploratory and descriptive research design was used. Twelve male amateur boxers participated in this study. The participants were all either provincially or nationally ranked, between the ages 16 and 22 and in the competitive phase of their training. The data was compared to find statistical significance and it was found from the Wilcoxon ranked sign test that distance does not affect total response time, change in total response time, number of punches and peak punch force fatigue resistance index. However, it was found that distance affects peak punch force. Additionally,it was found using a Spearman rank correlation test that older boxers proved to have statistically significant faster total response times, the boxers that had slower total reponse times proved to have statistically significant less powerful peak punch force, the boxers that had slower total response times proved to have statistically significant larger fatigue resistance index, boxers with larger change in total response time proved to have statistically significant more powerful peak punch force and the boxers with larger peak punch force proved to have statistically significant smaller fatigue resistance index. The data presented provides an introduction of the exploration of how distance from a target relates to a boxer’s performance.
- Full Text:
- Date Issued: 2012
Inhibitory potential of honey on the enzymatic activity of Helicobacter pylori urease
- Authors: Matongo, Fredrick
- Date: 2012
- Subjects: Honey , Helicobacter pylori infections , Enzyme inhibitors , Traditional medicine , Antifungal agents
- Language: English
- Type: Thesis , Masters , MSc (Biochemistry)
- Identifier: vital:11253 , http://hdl.handle.net/10353/431 , Honey , Helicobacter pylori infections , Enzyme inhibitors , Traditional medicine , Antifungal agents
- Description: Urease of Helicobacter pylori is an important virulence factor implicated in the pathogenesis of many clinical conditions, such as chronic gastritis, peptic ulceration, and gastric cancer. Many urease inhibitors have been discovered, like phosphorodiamidates, hydroxamic acid derivatives, and imidazoles. Despite good activities at the enzyme level and excellent kinetic properties most of them have not been used as therapeutic agents in vivo because of their side effects, toxicity and instability. This has led to much attention to focus on exploring the novel urease inhibitory activities of natural products because of their low toxicity and good bioavailability. Honey, a natural product has been used in folk medicine due to its antitumor, antioxidant, antimicrobial and anti-inflammatory properties. The aims of this study were to isolate, characterise, purify urease produced by H. pylori and investigate the inhibitory effects of solvent honey extracts on its enzymatic activity. Urease was found to be both surface-associated and cytoplasmic. Maximum cytoplasmic urease activity was found to occur after 72 hr whereas maximum extracellular urease activities were found to occur after 96 hr. Characterization of the crude cytoplasmic urease revealed optimal activity at a pH of 7.5 and temperature of 40°C. The kinetic parameters Vmax and Km were 45.32 U ml-1 and 61.11 mM respectively.The honey extracts inhibited the activity of the crude urease in a concentration dependent manner. The Lineweaver-Burk plots indicated a non-competitive type of inhibition against H. pylori urease. The two honey extracts gave promising inhibitory activities against urease of H. pylori. Thus the results of this study delineates that inhibition of urease can ease development in therapeutic and preventative approaches based on the enzymatic activity of this Helicobacter protein.
- Full Text:
- Date Issued: 2012
- Authors: Matongo, Fredrick
- Date: 2012
- Subjects: Honey , Helicobacter pylori infections , Enzyme inhibitors , Traditional medicine , Antifungal agents
- Language: English
- Type: Thesis , Masters , MSc (Biochemistry)
- Identifier: vital:11253 , http://hdl.handle.net/10353/431 , Honey , Helicobacter pylori infections , Enzyme inhibitors , Traditional medicine , Antifungal agents
- Description: Urease of Helicobacter pylori is an important virulence factor implicated in the pathogenesis of many clinical conditions, such as chronic gastritis, peptic ulceration, and gastric cancer. Many urease inhibitors have been discovered, like phosphorodiamidates, hydroxamic acid derivatives, and imidazoles. Despite good activities at the enzyme level and excellent kinetic properties most of them have not been used as therapeutic agents in vivo because of their side effects, toxicity and instability. This has led to much attention to focus on exploring the novel urease inhibitory activities of natural products because of their low toxicity and good bioavailability. Honey, a natural product has been used in folk medicine due to its antitumor, antioxidant, antimicrobial and anti-inflammatory properties. The aims of this study were to isolate, characterise, purify urease produced by H. pylori and investigate the inhibitory effects of solvent honey extracts on its enzymatic activity. Urease was found to be both surface-associated and cytoplasmic. Maximum cytoplasmic urease activity was found to occur after 72 hr whereas maximum extracellular urease activities were found to occur after 96 hr. Characterization of the crude cytoplasmic urease revealed optimal activity at a pH of 7.5 and temperature of 40°C. The kinetic parameters Vmax and Km were 45.32 U ml-1 and 61.11 mM respectively.The honey extracts inhibited the activity of the crude urease in a concentration dependent manner. The Lineweaver-Burk plots indicated a non-competitive type of inhibition against H. pylori urease. The two honey extracts gave promising inhibitory activities against urease of H. pylori. Thus the results of this study delineates that inhibition of urease can ease development in therapeutic and preventative approaches based on the enzymatic activity of this Helicobacter protein.
- Full Text:
- Date Issued: 2012
Institutional economics and the environment
- Authors: Fraser, Gavin C G
- Date: 2012
- Language: English
- Type: Text
- Identifier: vital:573 , http://hdl.handle.net/10962/d1006130
- Description: [From text] What is Institutional Economics? Before delving into the concept of institutional economics, it will be useful to explain what is meant by institutions because institutions in economics have a particular meaning. The most commonly agreed upon definition for institutions is a set of formal and informal rules of conduct that facilitate coordination or govern relationships between individuals or groups. The formal rules include laws, contracts, political systems, organisations, and markets, while the informal rules of conduct consist of norms, traditions, customs, value systems, religions and sociological trends. Institutions provide for more certainty in human interaction (North, 1990) and have an influence on outcomes such as economic performance, efficiency, economic growth and development. They can either benefit or hinder these economic measures. Williamson (2000) noted that new institutional economics operates at both the macro and micro levels. The macro level deals with the institutional environment, or the rules of the game, which affect the behaviour and performance of economic actors and in which organisational forms and transactions are embedded. Williamson (1993) described it as the set of fundamental political, social and legal ground rules that establish the basis for production, exchange and distribution. The micro level analysis known as the institutional arrangement, on the other hand, deals with the institutions of governance. These refer to the modes of managing transaction costs and include issues of social capital, property rights and collective action. Here the focus is on the individual transaction and the questions regarding organisational forms (private property versus common pool resources) are analysed. An institutional arrangement is an arrangement between economic units that govern the ways in which its members can co-operate or compete.
- Full Text:
- Date Issued: 2012
- Authors: Fraser, Gavin C G
- Date: 2012
- Language: English
- Type: Text
- Identifier: vital:573 , http://hdl.handle.net/10962/d1006130
- Description: [From text] What is Institutional Economics? Before delving into the concept of institutional economics, it will be useful to explain what is meant by institutions because institutions in economics have a particular meaning. The most commonly agreed upon definition for institutions is a set of formal and informal rules of conduct that facilitate coordination or govern relationships between individuals or groups. The formal rules include laws, contracts, political systems, organisations, and markets, while the informal rules of conduct consist of norms, traditions, customs, value systems, religions and sociological trends. Institutions provide for more certainty in human interaction (North, 1990) and have an influence on outcomes such as economic performance, efficiency, economic growth and development. They can either benefit or hinder these economic measures. Williamson (2000) noted that new institutional economics operates at both the macro and micro levels. The macro level deals with the institutional environment, or the rules of the game, which affect the behaviour and performance of economic actors and in which organisational forms and transactions are embedded. Williamson (1993) described it as the set of fundamental political, social and legal ground rules that establish the basis for production, exchange and distribution. The micro level analysis known as the institutional arrangement, on the other hand, deals with the institutions of governance. These refer to the modes of managing transaction costs and include issues of social capital, property rights and collective action. Here the focus is on the individual transaction and the questions regarding organisational forms (private property versus common pool resources) are analysed. An institutional arrangement is an arrangement between economic units that govern the ways in which its members can co-operate or compete.
- Full Text:
- Date Issued: 2012
Integrated leadership : a leadership approach for school management teams
- Hendricks, Clarence Nowellin
- Authors: Hendricks, Clarence Nowellin
- Date: 2012
- Subjects: Educational leadership -- South Africa , School management and organization
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9575 , http://hdl.handle.net/10948/d1018610
- Description: School managers currently face major challenges of finding innovative ways to improve the quality of teaching and learning and ultimately student outcomes. This might be because contemporary leadership models promote either requisite curricular expertise or requisite leadership qualities or requisite norms and values which impact notably on teaching and learning. This study examined to which extent School Management Teams (SMT’s) contribute to the quality of teaching and learning when utilizing an integrated leadership approach in primary schools.The extent to which integrated leadership contributes to the quality of teaching and learning is investigated through an exploratory mixed method approach. Case studies in six different schools were conducted through both qualitative and quantitative research methods to obtain data regarding the thirty-six participants’ integrated leadership qualities. Data was gathered through focused group interviews, observations and a questionnaire. The Annual National Assessment results for two consecutive years (2010 and 2011) of grade three and six learners for literacy and numeracy were collected to determine the relationship between integrated leadership and quality teaching and learning and the extent to which integrated leadership impacted on student outcomes.The findings revealed that SMT’s confused integrated leadership with the utilization of qualities from a range of leadership styles each seeking to fit the purpose of an activity, and then claim they are employing an integrated leadership approach. Integrated leadership on the contrary is one leadership model with different qualities and when utilised as a complete package, in a unified manner, has the potential to have a significant impact on the quality of teaching and learning and ultimately student achievement. The findings also indicated that the majority of SMT members are either not utilising integrated leadership or occasionally utilise some of the integrated leadership qualities. This might be one of the main reasons for unsatisfactory academic performance in schools. Integrated leadership thus, when implemented in its totality at all times, possesses all the qualities to have a significant impact on the quality of teaching and learning nationally and internationally.
- Full Text:
- Date Issued: 2012
- Authors: Hendricks, Clarence Nowellin
- Date: 2012
- Subjects: Educational leadership -- South Africa , School management and organization
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9575 , http://hdl.handle.net/10948/d1018610
- Description: School managers currently face major challenges of finding innovative ways to improve the quality of teaching and learning and ultimately student outcomes. This might be because contemporary leadership models promote either requisite curricular expertise or requisite leadership qualities or requisite norms and values which impact notably on teaching and learning. This study examined to which extent School Management Teams (SMT’s) contribute to the quality of teaching and learning when utilizing an integrated leadership approach in primary schools.The extent to which integrated leadership contributes to the quality of teaching and learning is investigated through an exploratory mixed method approach. Case studies in six different schools were conducted through both qualitative and quantitative research methods to obtain data regarding the thirty-six participants’ integrated leadership qualities. Data was gathered through focused group interviews, observations and a questionnaire. The Annual National Assessment results for two consecutive years (2010 and 2011) of grade three and six learners for literacy and numeracy were collected to determine the relationship between integrated leadership and quality teaching and learning and the extent to which integrated leadership impacted on student outcomes.The findings revealed that SMT’s confused integrated leadership with the utilization of qualities from a range of leadership styles each seeking to fit the purpose of an activity, and then claim they are employing an integrated leadership approach. Integrated leadership on the contrary is one leadership model with different qualities and when utilised as a complete package, in a unified manner, has the potential to have a significant impact on the quality of teaching and learning and ultimately student achievement. The findings also indicated that the majority of SMT members are either not utilising integrated leadership or occasionally utilise some of the integrated leadership qualities. This might be one of the main reasons for unsatisfactory academic performance in schools. Integrated leadership thus, when implemented in its totality at all times, possesses all the qualities to have a significant impact on the quality of teaching and learning nationally and internationally.
- Full Text:
- Date Issued: 2012
Integrated quality-management systems in selected schools : King William's Town Education District
- Authors: Mgijima, Khayakazi
- Date: 2012
- Subjects: School improvement programs -- South Africa -- King William's Town , Performance contracts in education -- South Africa -- King William's Town , Teachers -- Training of -- South Africa -- King William's Town
- Language: English
- Type: Thesis , Masters , MPA
- Identifier: vital:8295 , http://hdl.handle.net/10948/d1018892
- Description: The Integrated Quality Management System is a national policy that was introduced in 2003 by the Department of Education – with the aim of improving the performance of educators in teaching and learning. The policy integrates three programmes, namely: Developmental Appraisal, Performance Management and Whole-School Evaluation, which ought to complement one another, and run concurrently. The introduction and implementation of the Integrated Quality Management System is based on the premise that the quality of education in South African Schools would improve if the processes of the policy were used to evaluate and reward educators, and to institute corrective measures where necessary. The aim of the study was to evaluate the implementation of the Integrated Quality Management System for improving the quality of teaching and learning in schools. The study focused on schools in the King William’s Town Education District. Qualitative and quantitative research approaches were used to elicit the perceptions of educators, Senior Management Teams and District coordinators, with regard to the implementation process of the policy in the local schools. The findings indicate that the Department of Education needs to improve the processes of educating the educators in the implementation of the Integrated Quality Management system – in order to increase the possibility of achieving the objectives of the policy.
- Full Text:
- Date Issued: 2012
- Authors: Mgijima, Khayakazi
- Date: 2012
- Subjects: School improvement programs -- South Africa -- King William's Town , Performance contracts in education -- South Africa -- King William's Town , Teachers -- Training of -- South Africa -- King William's Town
- Language: English
- Type: Thesis , Masters , MPA
- Identifier: vital:8295 , http://hdl.handle.net/10948/d1018892
- Description: The Integrated Quality Management System is a national policy that was introduced in 2003 by the Department of Education – with the aim of improving the performance of educators in teaching and learning. The policy integrates three programmes, namely: Developmental Appraisal, Performance Management and Whole-School Evaluation, which ought to complement one another, and run concurrently. The introduction and implementation of the Integrated Quality Management System is based on the premise that the quality of education in South African Schools would improve if the processes of the policy were used to evaluate and reward educators, and to institute corrective measures where necessary. The aim of the study was to evaluate the implementation of the Integrated Quality Management System for improving the quality of teaching and learning in schools. The study focused on schools in the King William’s Town Education District. Qualitative and quantitative research approaches were used to elicit the perceptions of educators, Senior Management Teams and District coordinators, with regard to the implementation process of the policy in the local schools. The findings indicate that the Department of Education needs to improve the processes of educating the educators in the implementation of the Integrated Quality Management system – in order to increase the possibility of achieving the objectives of the policy.
- Full Text:
- Date Issued: 2012
Integrating stomach content and stable isotope analyses to elucidate the feeding habits of non-native sharptooth catfish Clarias gariepinus
- Kadye, Wilbert T, Booth, Anthony J
- Authors: Kadye, Wilbert T , Booth, Anthony J
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124843 , vital:35703 , https://doi.10.1007/s10530-011-0116-6
- Description: Sharptooth catfish Clarias gariepinus was introduced into the Eastern Cape Province, South Africa, in 1976 and there are concerns about its possible negative impacts on native biota. This study investigated its trophic impact by examining its feeding habits. Stomach content and stable isotope analyses were compared from three localities—the Great Fish River, Sundays River and Glen Melville Dam. Stomach content analysis indicated a catholic diet dominated by fish particularly in all localities.Spatially, however, the diets revealed differences based on the dominance of macrophytes that were only present in the rivers, and aquatic invertebrates that appeared more diverse within the Great Fish River compared to other localities. By contrast, stable isotopes revealed a more generalised feeding pattern with no clear dominance of particular prey. Stable isotopes further showed that the catfish was a complex predator, with large catfish being top predators whereas smaller size groups appeared to feed lower in the food chain. An ontogenetic shift in diet was evident, with small fish predominantly consuming aquatic invertebrates and shifting towards fish with increasing size. High dietary overlap suggests the potential risk associated catfish feeding, especially the potential of piscivory by small catfish that are more likely to persist in shallow and marginal where endangered indigenous minnows occur. The alteration of environmental conditions, especially flow by inter basin water transfer (IBWT) schemes, was inferred to have had a probable influence its invasion success. Occurrence of other invaders, which was facilitated by the IBWT together with the catfish, posits the risk of invasion meltdown within the study systems.
- Full Text:
- Date Issued: 2012
- Authors: Kadye, Wilbert T , Booth, Anthony J
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124843 , vital:35703 , https://doi.10.1007/s10530-011-0116-6
- Description: Sharptooth catfish Clarias gariepinus was introduced into the Eastern Cape Province, South Africa, in 1976 and there are concerns about its possible negative impacts on native biota. This study investigated its trophic impact by examining its feeding habits. Stomach content and stable isotope analyses were compared from three localities—the Great Fish River, Sundays River and Glen Melville Dam. Stomach content analysis indicated a catholic diet dominated by fish particularly in all localities.Spatially, however, the diets revealed differences based on the dominance of macrophytes that were only present in the rivers, and aquatic invertebrates that appeared more diverse within the Great Fish River compared to other localities. By contrast, stable isotopes revealed a more generalised feeding pattern with no clear dominance of particular prey. Stable isotopes further showed that the catfish was a complex predator, with large catfish being top predators whereas smaller size groups appeared to feed lower in the food chain. An ontogenetic shift in diet was evident, with small fish predominantly consuming aquatic invertebrates and shifting towards fish with increasing size. High dietary overlap suggests the potential risk associated catfish feeding, especially the potential of piscivory by small catfish that are more likely to persist in shallow and marginal where endangered indigenous minnows occur. The alteration of environmental conditions, especially flow by inter basin water transfer (IBWT) schemes, was inferred to have had a probable influence its invasion success. Occurrence of other invaders, which was facilitated by the IBWT together with the catfish, posits the risk of invasion meltdown within the study systems.
- Full Text:
- Date Issued: 2012
Inter-seasonal persistence and size-structuring of two minnow species within headwater streams in the Eastern Cape, South Africa
- Kadye, Wilbert T, Booth, Anthony J
- Authors: Kadye, Wilbert T , Booth, Anthony J
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124866 , vital:35705 , https://doi.10.1111/j.1439-0426.2012.02027.x
- Description: This study examined temporal variation in population dynamics and size structuring of two cyprinid minnows, Pseudobarbus afer and Barbus anoplus, in relation to their proximate physical habitats. Population estimates were determined using three-pass depletion sampling during both summer and winter. The habitats were characterised by seasonal variation in all physico-chemical conditions and spatial variation in substrata compositions. Whereas significant differences in population size were noted between seasons for B. anoplus, no differences were found between seasons for density and capture probability for either species. An increase in boulders was associated with increase in population size and density for P. afer; for B. anoplus, increased percentages of bedrock and bank vegetation were associated with an increase in population size and probability of capture, respectively. According to Canonical Correspondence Analysis, size structuring in P. afer was explained predominantly by seasonality, with smaller length classes associated with the seasonal variable of summer, while larger length classes were associated with pH that was higher in winter. By comparison, for B. anoplus, the habitat variables – bank vegetation and bedrock – accounted for much of the explained variance for size structuring. Recruitment appeared to be the major driver of size structuring for the two species; refugia, especially boulders and bank vegetation, also appeared to be important. Overall, the two species were adapted to the headwater streams that were generally variable in environmental conditions. Potential invasions by non-native invasive fishes that occur within the mainstream habitats threaten these two species. Efforts should continue to protect these minnows from such invasions by constructing barriers to upstream migration of non-native fishes into these headwater habitats.
- Full Text:
- Date Issued: 2012
- Authors: Kadye, Wilbert T , Booth, Anthony J
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124866 , vital:35705 , https://doi.10.1111/j.1439-0426.2012.02027.x
- Description: This study examined temporal variation in population dynamics and size structuring of two cyprinid minnows, Pseudobarbus afer and Barbus anoplus, in relation to their proximate physical habitats. Population estimates were determined using three-pass depletion sampling during both summer and winter. The habitats were characterised by seasonal variation in all physico-chemical conditions and spatial variation in substrata compositions. Whereas significant differences in population size were noted between seasons for B. anoplus, no differences were found between seasons for density and capture probability for either species. An increase in boulders was associated with increase in population size and density for P. afer; for B. anoplus, increased percentages of bedrock and bank vegetation were associated with an increase in population size and probability of capture, respectively. According to Canonical Correspondence Analysis, size structuring in P. afer was explained predominantly by seasonality, with smaller length classes associated with the seasonal variable of summer, while larger length classes were associated with pH that was higher in winter. By comparison, for B. anoplus, the habitat variables – bank vegetation and bedrock – accounted for much of the explained variance for size structuring. Recruitment appeared to be the major driver of size structuring for the two species; refugia, especially boulders and bank vegetation, also appeared to be important. Overall, the two species were adapted to the headwater streams that were generally variable in environmental conditions. Potential invasions by non-native invasive fishes that occur within the mainstream habitats threaten these two species. Efforts should continue to protect these minnows from such invasions by constructing barriers to upstream migration of non-native fishes into these headwater habitats.
- Full Text:
- Date Issued: 2012
Interaction of CdTe quantum dots with 2, 2-diphenyl-1-picrylhydrazyl free radical
- Adegoke, Oluwasesan, Chidawanyika, Wadzanai J U, Nyokong, Tebello
- Authors: Adegoke, Oluwasesan , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245751 , vital:51402 , xlink:href="https://doi.org/10.1007/s10895-011-1012-2"
- Description: The interaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH●) free radical with thiol-capped CdTe quantum dots (QDs) has been studied by UV–vis spectroscopy, steady state and time resolved fluorescence measurements. Addition of DPPH● radical to CdTe QDs resulted in fluorescence quenching. The interaction occurs through static quenching as this was confirmed by fluorescence lifetime measurements. Time course absorption studies indicates that DPPH● may be reduced by interaction with QDs to the substituted hydrazine form (2,2-diphenyl-1-picrylhydrazine) DPPH-H. The mechanism of fluorescence quenching of CdTe QDs by DPPH● is proposed.
- Full Text:
- Date Issued: 2012
- Authors: Adegoke, Oluwasesan , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245751 , vital:51402 , xlink:href="https://doi.org/10.1007/s10895-011-1012-2"
- Description: The interaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH●) free radical with thiol-capped CdTe quantum dots (QDs) has been studied by UV–vis spectroscopy, steady state and time resolved fluorescence measurements. Addition of DPPH● radical to CdTe QDs resulted in fluorescence quenching. The interaction occurs through static quenching as this was confirmed by fluorescence lifetime measurements. Time course absorption studies indicates that DPPH● may be reduced by interaction with QDs to the substituted hydrazine form (2,2-diphenyl-1-picrylhydrazine) DPPH-H. The mechanism of fluorescence quenching of CdTe QDs by DPPH● is proposed.
- Full Text:
- Date Issued: 2012
Interaction of terpenes and oxygenated terpenes with some drugs
- Authors: Ajayi, Emmanuel Olusegun
- Date: 2012
- Subjects: Terpenes -- Essences and essential oils , Lavenders -- Monoterpenes -- Drug interactions , Drugs -- Camphor -- Medicinal plants
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11332 , http://hdl.handle.net/10353/418 , Terpenes -- Essences and essential oils , Lavenders -- Monoterpenes -- Drug interactions , Drugs -- Camphor -- Medicinal plants
- Description: SFME and HD for the extraction of essential oil in Lavandula officinalis in Alice have been reported. A total of 59 compounds were identified with the major compound being 1,8-cineole, an oxygenated monoterpene, with 46.89% and 44.84% yield obtained for HD and SFME respectively. Charge transfer (CT) complexes formed between α-pinene, 1,8-cineole and camphor as electron donors with iodine as the electron acceptor have been studied spectrophotometrically in methylene chloride solution. The Benesi- Hildebrand equation has been applied to estimate the formation constant (Kf) and molecular extinction coefficient (εCT). The value of Kf is the highest in camphor-I2 complex compared to the other two complexes. Antibacterial assessment was carried out on the various reagents, determining the MIC of individual reagents and in combination. The results show an improvement, on combination of the various reagents than when tested alone.
- Full Text:
- Date Issued: 2012
- Authors: Ajayi, Emmanuel Olusegun
- Date: 2012
- Subjects: Terpenes -- Essences and essential oils , Lavenders -- Monoterpenes -- Drug interactions , Drugs -- Camphor -- Medicinal plants
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11332 , http://hdl.handle.net/10353/418 , Terpenes -- Essences and essential oils , Lavenders -- Monoterpenes -- Drug interactions , Drugs -- Camphor -- Medicinal plants
- Description: SFME and HD for the extraction of essential oil in Lavandula officinalis in Alice have been reported. A total of 59 compounds were identified with the major compound being 1,8-cineole, an oxygenated monoterpene, with 46.89% and 44.84% yield obtained for HD and SFME respectively. Charge transfer (CT) complexes formed between α-pinene, 1,8-cineole and camphor as electron donors with iodine as the electron acceptor have been studied spectrophotometrically in methylene chloride solution. The Benesi- Hildebrand equation has been applied to estimate the formation constant (Kf) and molecular extinction coefficient (εCT). The value of Kf is the highest in camphor-I2 complex compared to the other two complexes. Antibacterial assessment was carried out on the various reagents, determining the MIC of individual reagents and in combination. The results show an improvement, on combination of the various reagents than when tested alone.
- Full Text:
- Date Issued: 2012
Intercultural Communication and Vocational Language Learning in South Africa: Law and Healthcare
- Kaschula, Russell H, Maseko, Pamela
- Authors: Kaschula, Russell H , Maseko, Pamela
- Date: 2012
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/175234 , vital:42555 , ISBN 9781405162722 , DOI:10.1002/9781118247273
- Description: The Constitution (1996) of the Republic of South Africa recognizes eleven of South Africa’s most spoken languages as official languages of the country. Of the eleven languages, nine are indigenous African languages and are spoken by about 80% of the total population. The other two, English and Afrikaans, were the only official languages of the pre-democratic regime and are spoken by the remainder of the population. However, when it comes to vocational training at institutions of higher learning, the common trend in South Africa in terms of linguistic composition is in reverse. About 80% of the total student population have English or Afrikaans as their home language, whilst the minority are speakers of indigenous African languages. This is reflected in language practices in the majority of institutions of higher learning where English and Afrikaans are the most common media of instruction.
- Full Text:
- Date Issued: 2012
- Authors: Kaschula, Russell H , Maseko, Pamela
- Date: 2012
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/175234 , vital:42555 , ISBN 9781405162722 , DOI:10.1002/9781118247273
- Description: The Constitution (1996) of the Republic of South Africa recognizes eleven of South Africa’s most spoken languages as official languages of the country. Of the eleven languages, nine are indigenous African languages and are spoken by about 80% of the total population. The other two, English and Afrikaans, were the only official languages of the pre-democratic regime and are spoken by the remainder of the population. However, when it comes to vocational training at institutions of higher learning, the common trend in South Africa in terms of linguistic composition is in reverse. About 80% of the total student population have English or Afrikaans as their home language, whilst the minority are speakers of indigenous African languages. This is reflected in language practices in the majority of institutions of higher learning where English and Afrikaans are the most common media of instruction.
- Full Text:
- Date Issued: 2012
Interest rate pass-through in Cameroon and Nigeria: a comparative analysis
- Authors: Tita, Anthanasius Fomum
- Date: 2012
- Subjects: Interest rates -- Cameroon Interest rates -- Nigeria Interest rates -- Effect of inflation on -- Cameroon Interest rates -- Effect of inflation on -- Nigeria Interest rates -- Econometric models Cointegration Monetary policy -- Cameroon Monetary policy -- Nigeria Banque des états de l'Afrique centrale Banks and banking -- Cameroon Banks and banking -- Nigeria
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1005 , http://hdl.handle.net/10962/d1002740
- Description: One of the most important aspects of monetary policy is an understanding of the transmission process: the mechanism through which the monetary policy actions of the Central Bank impact on aggregate demand and prices by influencing the investment and consumption decisions of households and firms. Thus, commercial banks are regarded as conveyers of monetary policy shocks and are expected to adjust retail interest rates in response to policy shocks one-to-one. In practice, commercial banks adjust their retail rates in response to changes in monetary policy with a lag of several months and this delay is often viewed as an impediment on the ability of the Central Bank to steer the economy. Several reasons, such as credit rationing and adverse selection, switching costs, risk sharing, consumer irrationality, structure of the financial system, menu costs and asymmetric information are some of the causes advanced for commercial banks retail rates being sticky. In spite of the important role of pass-through analysis in the monetary policy transmission process, it has received very little attention in Sub-Saharan Africa, especially in Cameroon and Nigeria, which have implemented a series of reforms. To this end, this study gives a comparative analysis of interest rate pass-through in Nigeria and Cameroon using retail rates (lending and deposit) and a discount rate (policy rate) from January 1990 to December 2010 for Nigeria and from January 1990 to June 2008 for Cameroon. The study examines the magnitude and speed of retail rate adjustments to changes in the Central Bank policy rate as well as examining the possibility of symmetric and asymmetric pass-through in both countries. In addition, the study also investigates whether there is pass-through of monetary policy from one country to the other. The empirical analysis employs four different types of co-integration techniques to test the presence of a long run co-integrating relationship between retail and the policy rates in order to ensure that the relationship detected is robust. Three sets of analyses are carried out in the study. Following Cottarelli and Kourelis (1994), the study employed a co-integration technique, firstly, to analyse pass-through for the entire sample, secondly, to analyse symmetric and asymmetric pass-through using a ten year rolling window analysis in an error correction framework. Finally, the policy rates were swapped around to investigate if there are transmissions of impulses from one country to the other. Overall, evidence from the entire sample and rolling window analysis suggests that monetary policy in Cameroon is less effective. This is perhaps one of the reasons why the Banque Des Etats De L’Afrique Centrale (BEAC) is unable to sterilise the excess liquidity of the banking sector in Cameroon. The long run pass-through of 0.72 and 0.71 for the entire sample, and the average long run pass-through for the rolling window of 0.78 and 0.76 for the lending and deposit rates, suggest that monetary policy is highly effective in Nigeria compared to Cameroon. The empirical evidence confirmed asymmetric adjustment in six rolling windows in the lending rate in Nigeria. Three rolling windows indicated that the direction of rigidity is downward, supporting Scholnick’s (1996) collusive pricing arrangement between banks, and the other three suggested that the lending rate is rigid in the upward direction, corroborating Scholnick’s (1996) customer reaction hypothesis. The deposit rate in Cameroon was also found to adjust asymmetrically and the direction of rigidity is downward, supporting Hannan and Berger’s (1991) customer reaction hypothesis. The investigation of impulse transmission between the two countries revealed that only the policy rate in Nigeria exerts some influence on the deposit rate in Cameroon. Policy recommendations are also discussed.
- Full Text:
- Date Issued: 2012
- Authors: Tita, Anthanasius Fomum
- Date: 2012
- Subjects: Interest rates -- Cameroon Interest rates -- Nigeria Interest rates -- Effect of inflation on -- Cameroon Interest rates -- Effect of inflation on -- Nigeria Interest rates -- Econometric models Cointegration Monetary policy -- Cameroon Monetary policy -- Nigeria Banque des états de l'Afrique centrale Banks and banking -- Cameroon Banks and banking -- Nigeria
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1005 , http://hdl.handle.net/10962/d1002740
- Description: One of the most important aspects of monetary policy is an understanding of the transmission process: the mechanism through which the monetary policy actions of the Central Bank impact on aggregate demand and prices by influencing the investment and consumption decisions of households and firms. Thus, commercial banks are regarded as conveyers of monetary policy shocks and are expected to adjust retail interest rates in response to policy shocks one-to-one. In practice, commercial banks adjust their retail rates in response to changes in monetary policy with a lag of several months and this delay is often viewed as an impediment on the ability of the Central Bank to steer the economy. Several reasons, such as credit rationing and adverse selection, switching costs, risk sharing, consumer irrationality, structure of the financial system, menu costs and asymmetric information are some of the causes advanced for commercial banks retail rates being sticky. In spite of the important role of pass-through analysis in the monetary policy transmission process, it has received very little attention in Sub-Saharan Africa, especially in Cameroon and Nigeria, which have implemented a series of reforms. To this end, this study gives a comparative analysis of interest rate pass-through in Nigeria and Cameroon using retail rates (lending and deposit) and a discount rate (policy rate) from January 1990 to December 2010 for Nigeria and from January 1990 to June 2008 for Cameroon. The study examines the magnitude and speed of retail rate adjustments to changes in the Central Bank policy rate as well as examining the possibility of symmetric and asymmetric pass-through in both countries. In addition, the study also investigates whether there is pass-through of monetary policy from one country to the other. The empirical analysis employs four different types of co-integration techniques to test the presence of a long run co-integrating relationship between retail and the policy rates in order to ensure that the relationship detected is robust. Three sets of analyses are carried out in the study. Following Cottarelli and Kourelis (1994), the study employed a co-integration technique, firstly, to analyse pass-through for the entire sample, secondly, to analyse symmetric and asymmetric pass-through using a ten year rolling window analysis in an error correction framework. Finally, the policy rates were swapped around to investigate if there are transmissions of impulses from one country to the other. Overall, evidence from the entire sample and rolling window analysis suggests that monetary policy in Cameroon is less effective. This is perhaps one of the reasons why the Banque Des Etats De L’Afrique Centrale (BEAC) is unable to sterilise the excess liquidity of the banking sector in Cameroon. The long run pass-through of 0.72 and 0.71 for the entire sample, and the average long run pass-through for the rolling window of 0.78 and 0.76 for the lending and deposit rates, suggest that monetary policy is highly effective in Nigeria compared to Cameroon. The empirical evidence confirmed asymmetric adjustment in six rolling windows in the lending rate in Nigeria. Three rolling windows indicated that the direction of rigidity is downward, supporting Scholnick’s (1996) collusive pricing arrangement between banks, and the other three suggested that the lending rate is rigid in the upward direction, corroborating Scholnick’s (1996) customer reaction hypothesis. The deposit rate in Cameroon was also found to adjust asymmetrically and the direction of rigidity is downward, supporting Hannan and Berger’s (1991) customer reaction hypothesis. The investigation of impulse transmission between the two countries revealed that only the policy rate in Nigeria exerts some influence on the deposit rate in Cameroon. Policy recommendations are also discussed.
- Full Text:
- Date Issued: 2012