An investigation into the effects of socio-economic and education factors on WAIS-III performance in a stratified South African sample
- Authors: Kemp, Ryan
- Date: 2000
- Subjects: Wechsler Adult Intelligence Scale -- South Africa , Intelligence tests -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3002 , http://hdl.handle.net/10962/d1002511 , Wechsler Adult Intelligence Scale -- South Africa , Intelligence tests -- South Africa
- Description: The present study examined the effects of socio-economic status, quality and level of education on performance on the Wechsler Adult Intelligence Scale 3rd Edition r.:w AIS-III). The study was conducted within the context of the present Human Sciences Research Council (HSRC) W AIS-III standardisation process, cross-cultural psychometric research and the notion of test-wiseness. A South African sample (N = 68) comprising African first language (n = 40) and English first language (n = 28) participants, stratified for age (19 - 30 years), gender and educational attainment (Matric and Graduate) were utilised. Effects due to quality of education were determined by dividing the African language participants into those with private/model C schooling (n = 20) and those with DET schooling (n = 20). Effects due to level of education were determined by dividing the entire sample into those with Matric level education (n = 34) and those with Graduate level education (n = 34). Detailed demographic and socio-economic information were recorded for all participants, who completed the entire American version of the W AIS-III. Results revealed a highly significant positive correlation between high socio-economic status and W AIS-III Full Scale IQ. In addition the respective impact of the relatively poor quality of education and lower level of educational attainment on W AIS-III performance was substantial. These results were discussed in terms of their implications for cross-cultural research, the HSRC standardisation of the W AIS-III and the practical use of the W AIS-III in neuropsychological assessment.
- Full Text:
- Date Issued: 2000
- Authors: Kemp, Ryan
- Date: 2000
- Subjects: Wechsler Adult Intelligence Scale -- South Africa , Intelligence tests -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3002 , http://hdl.handle.net/10962/d1002511 , Wechsler Adult Intelligence Scale -- South Africa , Intelligence tests -- South Africa
- Description: The present study examined the effects of socio-economic status, quality and level of education on performance on the Wechsler Adult Intelligence Scale 3rd Edition r.:w AIS-III). The study was conducted within the context of the present Human Sciences Research Council (HSRC) W AIS-III standardisation process, cross-cultural psychometric research and the notion of test-wiseness. A South African sample (N = 68) comprising African first language (n = 40) and English first language (n = 28) participants, stratified for age (19 - 30 years), gender and educational attainment (Matric and Graduate) were utilised. Effects due to quality of education were determined by dividing the African language participants into those with private/model C schooling (n = 20) and those with DET schooling (n = 20). Effects due to level of education were determined by dividing the entire sample into those with Matric level education (n = 34) and those with Graduate level education (n = 34). Detailed demographic and socio-economic information were recorded for all participants, who completed the entire American version of the W AIS-III. Results revealed a highly significant positive correlation between high socio-economic status and W AIS-III Full Scale IQ. In addition the respective impact of the relatively poor quality of education and lower level of educational attainment on W AIS-III performance was substantial. These results were discussed in terms of their implications for cross-cultural research, the HSRC standardisation of the W AIS-III and the practical use of the W AIS-III in neuropsychological assessment.
- Full Text:
- Date Issued: 2000
An investigation into the influence of the environment on spawning aggregations and jig catches of chokka squid Loligo Vulgaris reynaudii off the south coast of South Africa
- Authors: Schön, Pieter-Jan
- Date: 2000
- Subjects: Squids -- Spawning , Squid fisheries -- South Africa , Squids , Shellfish fisheries -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5378 , http://hdl.handle.net/10962/d1016369
- Description: Erratic and highly variable catches in the South African chokka squid Loligo vulgaris reynaudii fishery, cause socio-economic hardship for the industry and uncertainty for resource managers. Catch forecasting can reduce this problem as it is believed that catch variability is strongly influenced by environmental factors. In this study, data were collected at varying temporal and spatial scales. Data for the hourly time-scale study were collected from 1996-1998, aboard commercial vessels, whilst for the longer time-scales, data were extracted for Kromme Bay (a single fishing area) from existing databases (1991-1998) that were comprised of compulsory catch returns and oceanographic data. The environment-catch relationship for chokka squid on the inshore spawning grounds was then investigated using multiple correlation and regression analysis, analysis of variance, contingency table analysis and cross-correlation statistical techniques. This simple, direct, 'black box' statistical approach was relatively successful in developing a predictive capability. On a short time-scale (hourly), the regression model accounted for 32% of the variability in catch, with turbidity the main determinant (13%). On a daily monthly time-scale, the best prediction model was on a monthly scale, accounting for 40% of the variability in catch. The principal determinant, bottom temperature anomaly (11 %), was found to lag one month forward. Seasonal and diel catch variations induced changes in the relative importance of turbidity, water temperature and wind direction on catches. A strong, positive relationship was found between easterly winds (which cause upwelling) and catch, particularly in summer. Catch rates, however, decreased with an increase in turbidity. The correlation between temperature and catch was generally negative, however, higher catches were associated with a temperature range of 13-18°C. Highest catch rates were associated with easterly winds, zero turbidity conditions and sea surface temperatures from 15.0-16.9°C. Selected case studies (in situ observations) suggested that upwelling and turbidity events act as environmental triggers for the initiation or termination of the spawning process, respectively. A holistic approach is required to improve predictive capability of chokka squid abundance. Although short-term predictability remains essential (i.e. hourly-scale), future research should concentrate on long-term prediction models (e.g., monthly time-scales) involving greater spatial variation, which are the most important for management.
- Full Text:
- Date Issued: 2000
- Authors: Schön, Pieter-Jan
- Date: 2000
- Subjects: Squids -- Spawning , Squid fisheries -- South Africa , Squids , Shellfish fisheries -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5378 , http://hdl.handle.net/10962/d1016369
- Description: Erratic and highly variable catches in the South African chokka squid Loligo vulgaris reynaudii fishery, cause socio-economic hardship for the industry and uncertainty for resource managers. Catch forecasting can reduce this problem as it is believed that catch variability is strongly influenced by environmental factors. In this study, data were collected at varying temporal and spatial scales. Data for the hourly time-scale study were collected from 1996-1998, aboard commercial vessels, whilst for the longer time-scales, data were extracted for Kromme Bay (a single fishing area) from existing databases (1991-1998) that were comprised of compulsory catch returns and oceanographic data. The environment-catch relationship for chokka squid on the inshore spawning grounds was then investigated using multiple correlation and regression analysis, analysis of variance, contingency table analysis and cross-correlation statistical techniques. This simple, direct, 'black box' statistical approach was relatively successful in developing a predictive capability. On a short time-scale (hourly), the regression model accounted for 32% of the variability in catch, with turbidity the main determinant (13%). On a daily monthly time-scale, the best prediction model was on a monthly scale, accounting for 40% of the variability in catch. The principal determinant, bottom temperature anomaly (11 %), was found to lag one month forward. Seasonal and diel catch variations induced changes in the relative importance of turbidity, water temperature and wind direction on catches. A strong, positive relationship was found between easterly winds (which cause upwelling) and catch, particularly in summer. Catch rates, however, decreased with an increase in turbidity. The correlation between temperature and catch was generally negative, however, higher catches were associated with a temperature range of 13-18°C. Highest catch rates were associated with easterly winds, zero turbidity conditions and sea surface temperatures from 15.0-16.9°C. Selected case studies (in situ observations) suggested that upwelling and turbidity events act as environmental triggers for the initiation or termination of the spawning process, respectively. A holistic approach is required to improve predictive capability of chokka squid abundance. Although short-term predictability remains essential (i.e. hourly-scale), future research should concentrate on long-term prediction models (e.g., monthly time-scales) involving greater spatial variation, which are the most important for management.
- Full Text:
- Date Issued: 2000
An investigation into tools and protocols for commercial audio web-site creation
- Authors: Ndinga, S'busiso Simon
- Date: 2000
- Subjects: Web sites -- Design , Digital libraries , Internet -- Security measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4621 , http://hdl.handle.net/10962/d1006488 , Web sites -- Design , Digital libraries , Internet -- Security measures
- Description: This thesis presents a feasibility study of a Web-based digital music library and purchasing system. It investigates the current status of the enabling technologies for developing such a system. An analysis of various Internet audio codecs, streaming audio protocols, Internet credit card payment security methods, and ways for accessing remote Web databases is presented. The objective of the analysis is to determine the viability and the economic benefits of using these technologies when developing systems that facilitate music distribution over the Internet. A prototype of a distributed digital music library and purchasing system named WAPS (for Web-based Audio Purchasing System) was developed and implemented in the Java programming language. In this thesis both the physical and the logical component elements of WAPS are explored in depth so as to provide an insight into the inherent problems of creating such a system, as well as the overriding benefits derived from the creation of such a system.
- Full Text:
- Date Issued: 2000
- Authors: Ndinga, S'busiso Simon
- Date: 2000
- Subjects: Web sites -- Design , Digital libraries , Internet -- Security measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4621 , http://hdl.handle.net/10962/d1006488 , Web sites -- Design , Digital libraries , Internet -- Security measures
- Description: This thesis presents a feasibility study of a Web-based digital music library and purchasing system. It investigates the current status of the enabling technologies for developing such a system. An analysis of various Internet audio codecs, streaming audio protocols, Internet credit card payment security methods, and ways for accessing remote Web databases is presented. The objective of the analysis is to determine the viability and the economic benefits of using these technologies when developing systems that facilitate music distribution over the Internet. A prototype of a distributed digital music library and purchasing system named WAPS (for Web-based Audio Purchasing System) was developed and implemented in the Java programming language. In this thesis both the physical and the logical component elements of WAPS are explored in depth so as to provide an insight into the inherent problems of creating such a system, as well as the overriding benefits derived from the creation of such a system.
- Full Text:
- Date Issued: 2000
An investigation of male and female cognitive ability on the WAIS-III
- Authors: Muirhead, Joanne
- Date: 2000
- Subjects: Wechsler Adult Intelligence Scale , Sex differences (Psychology) , Intelligence tests -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3028 , http://hdl.handle.net/10962/d1002537 , Wechsler Adult Intelligence Scale , Sex differences (Psychology) , Intelligence tests -- South Africa
- Description: This study, which formed part of a larger research project, investigated the effect of gender on test performance on the Wechsler Adult Intelligence Scale - Third Edition (WAIS-III). The WAIS-III was administered to a sample of 68 participants in the Eastern Cape following the initiative of the Human Sciences Research Council to standardise the WAIS-III for a South African population. The participants, aged 19 to 30, were stratified according to language of origin (African or English First Language), educational attainment (matriculant or graduate), quality of education (Department of Education and Training or private/"Model C" school) and gender. Analyses of variance and two sample t tests were used to compare male and female test performance. For the total sample, no significant difference between males and females on Verbal, Performance and Full Scale IQ were found. On the factor indices, females scored marginally higher than males on Processing Speed at a level which was approaching significance (p = 0.105), but no significant differences were found. On subtest performance, females significantly outperformed males on Digit Symbol (p = 0.020). Differences which were approaching significance were found on Information (p = 0.133) in favour of males, and on Matrix Reasoning (p = 0.092) in favour of females. For subgroups of the total sample, the most significant differences in test performance were found for the African First Language private/"Model C" school cohort in favour of females. Thus the overriding implication that emerged from this research was that on this relatively highly educated sample, no significant gender differences in cognitive ability were apparent.
- Full Text:
- Date Issued: 2000
- Authors: Muirhead, Joanne
- Date: 2000
- Subjects: Wechsler Adult Intelligence Scale , Sex differences (Psychology) , Intelligence tests -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3028 , http://hdl.handle.net/10962/d1002537 , Wechsler Adult Intelligence Scale , Sex differences (Psychology) , Intelligence tests -- South Africa
- Description: This study, which formed part of a larger research project, investigated the effect of gender on test performance on the Wechsler Adult Intelligence Scale - Third Edition (WAIS-III). The WAIS-III was administered to a sample of 68 participants in the Eastern Cape following the initiative of the Human Sciences Research Council to standardise the WAIS-III for a South African population. The participants, aged 19 to 30, were stratified according to language of origin (African or English First Language), educational attainment (matriculant or graduate), quality of education (Department of Education and Training or private/"Model C" school) and gender. Analyses of variance and two sample t tests were used to compare male and female test performance. For the total sample, no significant difference between males and females on Verbal, Performance and Full Scale IQ were found. On the factor indices, females scored marginally higher than males on Processing Speed at a level which was approaching significance (p = 0.105), but no significant differences were found. On subtest performance, females significantly outperformed males on Digit Symbol (p = 0.020). Differences which were approaching significance were found on Information (p = 0.133) in favour of males, and on Matrix Reasoning (p = 0.092) in favour of females. For subgroups of the total sample, the most significant differences in test performance were found for the African First Language private/"Model C" school cohort in favour of females. Thus the overriding implication that emerged from this research was that on this relatively highly educated sample, no significant gender differences in cognitive ability were apparent.
- Full Text:
- Date Issued: 2000
An investigation of parental non-involvement in the governance of a Duncan Village school and its implications for the management of the school : a case study
- Authors: Ndlazi, Sibongile Mandisa
- Date: 2000
- Subjects: School management and organization -- South Africa -- Eastern Cape Education -- Parent participation -- South Africa Education -- Parent participation -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1639 , http://hdl.handle.net/10962/d1003521
- Description: This study explores the perceptions that parents have about their non-involvement in the governance of a Duncan Village High School, and considers the implications of such perceptions for the management of the school. Recent discussions on Radio Talk Shows and articles written in local newspapers indicate that Black parents have generally not been involved in the education of their children at the traditionally Black schools. Parental non-involvement also emerges as a strong theme in recent research. However, most of the research and media coverage focuses on school management's perceptions of the reasons and consequences of such non-involvement. The parents' voices have rarely been heard. Against this background, as well as the fact that the South African Schools Act presents a strong case for the involvement of parents in school governance and management, a phenomenological investigation was conducted at a traditionally Black Duncan Village High School. I chose phenomenology because I believed this approach has the potential for revealing my respondents' attitudes and perceptions. The sample consisted of four parent members of the school governing body who were key informants. The respondents were subjected to unstructured interviews which were held at their homes. The interviews probed the background and reasons for their lack of involvement, and the possible implications ofthis non-involvement for school management. The most significant of the wealth of findings is that parental non-involvement is linked to the historical background of the culture of non-participation of Black people which was created and encouraged by the successive White Governments in South Africa.
- Full Text:
- Date Issued: 2000
- Authors: Ndlazi, Sibongile Mandisa
- Date: 2000
- Subjects: School management and organization -- South Africa -- Eastern Cape Education -- Parent participation -- South Africa Education -- Parent participation -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1639 , http://hdl.handle.net/10962/d1003521
- Description: This study explores the perceptions that parents have about their non-involvement in the governance of a Duncan Village High School, and considers the implications of such perceptions for the management of the school. Recent discussions on Radio Talk Shows and articles written in local newspapers indicate that Black parents have generally not been involved in the education of their children at the traditionally Black schools. Parental non-involvement also emerges as a strong theme in recent research. However, most of the research and media coverage focuses on school management's perceptions of the reasons and consequences of such non-involvement. The parents' voices have rarely been heard. Against this background, as well as the fact that the South African Schools Act presents a strong case for the involvement of parents in school governance and management, a phenomenological investigation was conducted at a traditionally Black Duncan Village High School. I chose phenomenology because I believed this approach has the potential for revealing my respondents' attitudes and perceptions. The sample consisted of four parent members of the school governing body who were key informants. The respondents were subjected to unstructured interviews which were held at their homes. The interviews probed the background and reasons for their lack of involvement, and the possible implications ofthis non-involvement for school management. The most significant of the wealth of findings is that parental non-involvement is linked to the historical background of the culture of non-participation of Black people which was created and encouraged by the successive White Governments in South Africa.
- Full Text:
- Date Issued: 2000
An investigative case study of the introduction of democratic decision-making within an East London secondary school
- Authors: Carelse, Garth Craig
- Date: 2000
- Subjects: School management and organization -- South Africa Decision making -- Cast studies Education and state Ebenezer Majombozi High
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1920 , http://hdl.handle.net/10962/d1007404
- Description: The move towards greater democracy and participation in our education system is legislated quite succinctly in our South African Schools Act. The Act furthermore, and more importantly for this case study, posits that decision-making should be democratic in nature and our schools should eventually become governed in a collaborative and co-operative manner. Other policy texts such as the Labour Relations Act and the South African Constitution canonise the demand for a democratic South African society. This study investigates how democratic decision-making practices are taking place in an East London Secondary School namely Ebenezer Majombozi High. Even though distinct links exist between management and governance arms of schools, this study concentrates predominantly on decision-making within the school governing body and touches briefly on management thinking trends as a theoretical background to the kind of management at the school. What makes the school interesting as a case study is its rich history and its location in a deprived and impoverished township environment. The school was also part of the ex-Department of Education and Training, the black educational department of the past apartheid state. The kind of research undertaken was in the form of unstructured personal interviews with influential stakeholders at the school. Some of these stakeholders fonn part of the school governing body and the questions asked probed forms of governance at the school and how decision-making impacted on the overall school governance. The research findings acknowledges that decision-making does occur democratically at the school but that the practical implementation of positive consensual decisions are rarely realized. The school governing body only meets to deal with crises underpinned by a lack of learning and teaching and has not even debated the policies within the South African Schools Act. The study also argues that only by building capacity within the school and empowering the stakeholders, can constructive participation by all become a reality.
- Full Text:
- Date Issued: 2000
- Authors: Carelse, Garth Craig
- Date: 2000
- Subjects: School management and organization -- South Africa Decision making -- Cast studies Education and state Ebenezer Majombozi High
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1920 , http://hdl.handle.net/10962/d1007404
- Description: The move towards greater democracy and participation in our education system is legislated quite succinctly in our South African Schools Act. The Act furthermore, and more importantly for this case study, posits that decision-making should be democratic in nature and our schools should eventually become governed in a collaborative and co-operative manner. Other policy texts such as the Labour Relations Act and the South African Constitution canonise the demand for a democratic South African society. This study investigates how democratic decision-making practices are taking place in an East London Secondary School namely Ebenezer Majombozi High. Even though distinct links exist between management and governance arms of schools, this study concentrates predominantly on decision-making within the school governing body and touches briefly on management thinking trends as a theoretical background to the kind of management at the school. What makes the school interesting as a case study is its rich history and its location in a deprived and impoverished township environment. The school was also part of the ex-Department of Education and Training, the black educational department of the past apartheid state. The kind of research undertaken was in the form of unstructured personal interviews with influential stakeholders at the school. Some of these stakeholders fonn part of the school governing body and the questions asked probed forms of governance at the school and how decision-making impacted on the overall school governance. The research findings acknowledges that decision-making does occur democratically at the school but that the practical implementation of positive consensual decisions are rarely realized. The school governing body only meets to deal with crises underpinned by a lack of learning and teaching and has not even debated the policies within the South African Schools Act. The study also argues that only by building capacity within the school and empowering the stakeholders, can constructive participation by all become a reality.
- Full Text:
- Date Issued: 2000
Aspects of reproduction in the four-striped field mouse, Rhabdomys pumilio
- Authors: Jackson, Claire
- Date: 2000
- Subjects: Microtus , Mice , Mice -- Reproduction
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5637 , http://hdl.handle.net/10962/d1005319 , Microtus , Mice , Mice -- Reproduction
- Description: Rhabdomys pumilio, in the Eastern Cape of South Africa, does not use short day length as an inhibitory cue for reproductive activity, and, despite previous records indicating that these mice are strictly seasonal in their reproduction, litters have been found during the winters of some years,both in the Eastern Cape and in the Western Cape. This led me to believe that the reproductive activity of Rhabdomys pumilio is more opportunistic and that the cue or cues used to control reproduction are less predictable and, or more variable than the photoperiod cue used by many seasonally reproducing rodents. Two experiments were conducted, investigating the influence of low ambient temperature (15⁰C)and reduced food availability on the reproductive activity of both male and female four striped field mice. Mice were maintained in one of four conditions (food restricted at 15⁰C, food restricted at 26⁰C, ad lib. food at 15⁰C, and ad lib. food at 26⁰C) for 4 (males) and 8 weeks (females)(photoperiod 12L:12D, humidity 40%). Results indicated that the males reduced their reproductive activity slightly when exposed to either low temperature or low food availability and that maximum inhibition of reproduction occurred when mice were exposed to both low temperature and low food availability. However, female reproductive activity was inhibited when exposed to low food availability, irrespective of the temperature. Both sexes of mice showed varying abilities to resist fat loss and, in the males, the size of the fat store had a significant effect on reproduction. This varying ability to resist fat loss could be related to levels of activity and in the females (where activity was quantified), high activity scores were significantly associated with reproductive inhibition. These results support the hypothesis that reproduction in Rhabdomys pumilio is opportunistic and controlled by the availability of energy. I propose that the females will be more sensitive to reproductive inhibition due to their far greater post-fertilization responsibilities, where the reproductive activity of the females is rapidly inhibited by a reduction in food availability, while the males are less readily inhibited by low food availability or low temperature, unless the change in the controlling factors is severe enough, or prolonged, at which stage their reproductive activity will cease. The significance of opportunistic reproduction in the seasonal but unpredictable climate of the study area is discussed.
- Full Text:
- Date Issued: 2000
- Authors: Jackson, Claire
- Date: 2000
- Subjects: Microtus , Mice , Mice -- Reproduction
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5637 , http://hdl.handle.net/10962/d1005319 , Microtus , Mice , Mice -- Reproduction
- Description: Rhabdomys pumilio, in the Eastern Cape of South Africa, does not use short day length as an inhibitory cue for reproductive activity, and, despite previous records indicating that these mice are strictly seasonal in their reproduction, litters have been found during the winters of some years,both in the Eastern Cape and in the Western Cape. This led me to believe that the reproductive activity of Rhabdomys pumilio is more opportunistic and that the cue or cues used to control reproduction are less predictable and, or more variable than the photoperiod cue used by many seasonally reproducing rodents. Two experiments were conducted, investigating the influence of low ambient temperature (15⁰C)and reduced food availability on the reproductive activity of both male and female four striped field mice. Mice were maintained in one of four conditions (food restricted at 15⁰C, food restricted at 26⁰C, ad lib. food at 15⁰C, and ad lib. food at 26⁰C) for 4 (males) and 8 weeks (females)(photoperiod 12L:12D, humidity 40%). Results indicated that the males reduced their reproductive activity slightly when exposed to either low temperature or low food availability and that maximum inhibition of reproduction occurred when mice were exposed to both low temperature and low food availability. However, female reproductive activity was inhibited when exposed to low food availability, irrespective of the temperature. Both sexes of mice showed varying abilities to resist fat loss and, in the males, the size of the fat store had a significant effect on reproduction. This varying ability to resist fat loss could be related to levels of activity and in the females (where activity was quantified), high activity scores were significantly associated with reproductive inhibition. These results support the hypothesis that reproduction in Rhabdomys pumilio is opportunistic and controlled by the availability of energy. I propose that the females will be more sensitive to reproductive inhibition due to their far greater post-fertilization responsibilities, where the reproductive activity of the females is rapidly inhibited by a reduction in food availability, while the males are less readily inhibited by low food availability or low temperature, unless the change in the controlling factors is severe enough, or prolonged, at which stage their reproductive activity will cease. The significance of opportunistic reproduction in the seasonal but unpredictable climate of the study area is discussed.
- Full Text:
- Date Issued: 2000
Aspects of the ecology and reproductive biology of the limpet, Helcion pruinosus (Gastropoda : prosobranchia)
- Authors: Henninger, Tony Oskar
- Date: 2000
- Subjects: Prosobranchia , Limpets -- Reproduction , Limpets -- Ecology , Prosobranchia -- Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5641 , http://hdl.handle.net/10962/d1005323 , Prosobranchia , Limpets -- Reproduction , Limpets -- Ecology , Prosobranchia -- Ecology
- Description: Helcion pruinosus, the rayed limpet, is found in the midshore region of the intertidal zone, (i.e. the Balanoid zone) of rocky shores, from Saldanha Bay to Sodwana Bay along the coast of South Africa. At Gonubie (32°57'S/25°01'E) this species of limpet was found under boulders, (when not feeding), and could reach average densities of 85/ m². The limpets prefer smooth boulders, avoiding those encrusted by coralline algae or boulders with a rough texture. There was no habitat segregation between adult and juvenile H. pruinosus, i.e. there was no sign of up-shore migration by larger individuals. Males out-numbered females by, on average 1.4 : 1, which was a similar sex ratio to that of the congeneric species, H. pectunculus (Gray, 996). Unlike H. pectunculus, there were no differences in shell lengths between males and females (p = 0.946 at Gonubie, south-east coast and p = 0.961 at Kommetjie, south-west coast; t-test). Shell height could also not be used as a criterion to differentiate between the sexes. The average maximum shell length of H. pruinosus at Gonubie and Kommetjie was 25 mm, but the maximum shell lengths found were 30 mm, (one individual in each case), on both the southeast coast and west coast. Growth occurred most rapidly in the first year of life, with individuals reaching 15 mm after 1 year. In the second year limpet growth slowed to only 7 mm. Sexual maturity was reached at a shell length of between 11 to 14 mm (at an age of 8 months to 1 year). The life-span of H. pruinosus was determined at 2.55 years on the south-east coast and 2.9 years on the south-west coast. Micro-growth bands were produced tidally. Growth occurred allometrically, i.e. shell length increased at a faster rate than shell height. The limpets foraged during low tide, at night, presumably feeding on epilithic algae on the boulders. A second smaller peak of limpet activity was often recorded during the day, when low tide coincided with dawn). More limpets (up to ten times more) were active at spring tides compared to neap tides. Limpet activity was greatest during the spring tides of autumn. During all seasons limpet activity peaked 30 minutes before low water, after which numbers decreased rapidly. All limpets had retreated beneath the boulders before being covered by the flooding tide. It was concluded that the limpets were responding to both endogenous and exogenous cues, but the actual stimulus for retreat could not be determined. The limpets did not return to a fixed scar nor did they return rigidly to a home site. H. pruinosus was found to be gonochoristic. Sexes could be separated, on dissection, according to the colour of their gonads (males had white gonads, whilst that of the females was olive-green). Gonads were present throughout the year in most individuals, i.e. totally spent animals were never observed. Reproductive seasonality was similar in west coast and south-east coast animals. The gonad indices of the west coast limpets were higher, (maximum of 35%), compared to that on the southeast coast, (25%). The animals were probably trickle spawners, with some individuals liberating gametes throughout the year. There was however synchrony in gametogenesis between male and female limpets on both the west coast and south-east coast lines. Gonad indices peaked in the summer months (October to December) with a second minor peak in April/May. These peaks occurred before the release of the gametes in spawning events. The gonad index was lowest in winter, (July). The ovaries were full of mature eggs (oocytes having a diameter of 200 to 250 ~) prior to spawning. The acinal wall thickness had been decreasing prior to spawning. After spawning there was an increase in previtellogenic eggs « 100 μm) in females, and an increase in the acinal wall thickness to indicate spermatogenesis. The two populations are subjected to different environmental conditions and the actual cue for stimulating the release of gametes could not be determined. Finally, a table of differences between H pruinosus and its sister species, H pectunculus was created to show the life-style of H pruinosus.
- Full Text:
- Date Issued: 2000
- Authors: Henninger, Tony Oskar
- Date: 2000
- Subjects: Prosobranchia , Limpets -- Reproduction , Limpets -- Ecology , Prosobranchia -- Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5641 , http://hdl.handle.net/10962/d1005323 , Prosobranchia , Limpets -- Reproduction , Limpets -- Ecology , Prosobranchia -- Ecology
- Description: Helcion pruinosus, the rayed limpet, is found in the midshore region of the intertidal zone, (i.e. the Balanoid zone) of rocky shores, from Saldanha Bay to Sodwana Bay along the coast of South Africa. At Gonubie (32°57'S/25°01'E) this species of limpet was found under boulders, (when not feeding), and could reach average densities of 85/ m². The limpets prefer smooth boulders, avoiding those encrusted by coralline algae or boulders with a rough texture. There was no habitat segregation between adult and juvenile H. pruinosus, i.e. there was no sign of up-shore migration by larger individuals. Males out-numbered females by, on average 1.4 : 1, which was a similar sex ratio to that of the congeneric species, H. pectunculus (Gray, 996). Unlike H. pectunculus, there were no differences in shell lengths between males and females (p = 0.946 at Gonubie, south-east coast and p = 0.961 at Kommetjie, south-west coast; t-test). Shell height could also not be used as a criterion to differentiate between the sexes. The average maximum shell length of H. pruinosus at Gonubie and Kommetjie was 25 mm, but the maximum shell lengths found were 30 mm, (one individual in each case), on both the southeast coast and west coast. Growth occurred most rapidly in the first year of life, with individuals reaching 15 mm after 1 year. In the second year limpet growth slowed to only 7 mm. Sexual maturity was reached at a shell length of between 11 to 14 mm (at an age of 8 months to 1 year). The life-span of H. pruinosus was determined at 2.55 years on the south-east coast and 2.9 years on the south-west coast. Micro-growth bands were produced tidally. Growth occurred allometrically, i.e. shell length increased at a faster rate than shell height. The limpets foraged during low tide, at night, presumably feeding on epilithic algae on the boulders. A second smaller peak of limpet activity was often recorded during the day, when low tide coincided with dawn). More limpets (up to ten times more) were active at spring tides compared to neap tides. Limpet activity was greatest during the spring tides of autumn. During all seasons limpet activity peaked 30 minutes before low water, after which numbers decreased rapidly. All limpets had retreated beneath the boulders before being covered by the flooding tide. It was concluded that the limpets were responding to both endogenous and exogenous cues, but the actual stimulus for retreat could not be determined. The limpets did not return to a fixed scar nor did they return rigidly to a home site. H. pruinosus was found to be gonochoristic. Sexes could be separated, on dissection, according to the colour of their gonads (males had white gonads, whilst that of the females was olive-green). Gonads were present throughout the year in most individuals, i.e. totally spent animals were never observed. Reproductive seasonality was similar in west coast and south-east coast animals. The gonad indices of the west coast limpets were higher, (maximum of 35%), compared to that on the southeast coast, (25%). The animals were probably trickle spawners, with some individuals liberating gametes throughout the year. There was however synchrony in gametogenesis between male and female limpets on both the west coast and south-east coast lines. Gonad indices peaked in the summer months (October to December) with a second minor peak in April/May. These peaks occurred before the release of the gametes in spawning events. The gonad index was lowest in winter, (July). The ovaries were full of mature eggs (oocytes having a diameter of 200 to 250 ~) prior to spawning. The acinal wall thickness had been decreasing prior to spawning. After spawning there was an increase in previtellogenic eggs « 100 μm) in females, and an increase in the acinal wall thickness to indicate spermatogenesis. The two populations are subjected to different environmental conditions and the actual cue for stimulating the release of gametes could not be determined. Finally, a table of differences between H pruinosus and its sister species, H pectunculus was created to show the life-style of H pruinosus.
- Full Text:
- Date Issued: 2000
Assessing alternative assessment: students' experiences of the different forms of assessment in a Bachelor of Education course
- Authors: Hendricks, Monica
- Date: 2000
- Subjects: Education, Higher -- South Africa -- Evaluation Educational tests and measurements -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1424 , http://hdl.handle.net/10962/d1003305
- Description: In this study I examine the current alternative forms of assessment that were employed in the foundation year of the Bachelor of Education course at Rhodes University in 1998. Since assessment is concerned with ascertaining the amount, and kind, of learning that has taken place, it links learning and teaching. As my role in the course was academic development, I was interested in the nature ofthe development that the course promoted, for lecturers and students. My main intention was to gain insight into students' experiences of the assessment practices. To this end I selected six students, photocopied all their academic writing for the year and interviewed them. In addition, to provide a holistic picture of assessment and marking, I interviewed the six lecturers who team-taught the course. The data thus included the course assignments of the six students and an interview with each student as well as with the course lecturers. The findings show that though policy documents advocate alternative forms of assessment, implementing such assessment is a complex matter for both teachers and students.
- Full Text:
- Date Issued: 2000
- Authors: Hendricks, Monica
- Date: 2000
- Subjects: Education, Higher -- South Africa -- Evaluation Educational tests and measurements -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1424 , http://hdl.handle.net/10962/d1003305
- Description: In this study I examine the current alternative forms of assessment that were employed in the foundation year of the Bachelor of Education course at Rhodes University in 1998. Since assessment is concerned with ascertaining the amount, and kind, of learning that has taken place, it links learning and teaching. As my role in the course was academic development, I was interested in the nature ofthe development that the course promoted, for lecturers and students. My main intention was to gain insight into students' experiences of the assessment practices. To this end I selected six students, photocopied all their academic writing for the year and interviewed them. In addition, to provide a holistic picture of assessment and marking, I interviewed the six lecturers who team-taught the course. The data thus included the course assignments of the six students and an interview with each student as well as with the course lecturers. The findings show that though policy documents advocate alternative forms of assessment, implementing such assessment is a complex matter for both teachers and students.
- Full Text:
- Date Issued: 2000
Asymmetric α-alkylation reactions
- Authors: Klein, Rosalyn
- Date: 2000
- Subjects: Asymmetric synthesis , Alkylation , Chemical reactions
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4405 , http://hdl.handle.net/10962/d1006710 , Asymmetric synthesis , Alkylation , Chemical reactions
- Description: A novel camphor-derived hydroxy ketal 138 has been developed as a crural auxiliary, and used to prepare a series of six carboxylic esters of increasing steric bulk. The α-benzylation of this series of esters was achieved with diastereoselectivities of 59 - 83% d. e. and in 39 - 48% material yield. These results compared very favourably with those obtained in earlier studies using a regioisomeric analogue as the chiral auxiliary. Computer.modelling studies of the putative enolate intermediate has provided some insight into the possible mode of electrophilic attack at the α-carbon and the roles of the ketal protecting group and the lithium cation in these asymmetric transformations. In a related investigation, based on earlier work, a camphor-derived imino lactone has provided convenient access to α-alkyl α-amino acids, the imino lactone serving as a masked glycine equivalent. Using straight chain primary alkyl iodides [RI; R = Me, Et, Pr, Bu, CH₃(CH₂)₄ and CH₃(CH₄)₅], alkylation of the potassium enolate of the camphor-derived imino lactone was effected with 54 - 89% d.e. and in 54 - 87% material yield. Four novel alkylated derivatives were synthesised using isopropyl iodide, sec-butyl iodide and allyl iodide, the latter reagent resulting in both the monoallylated and diallylated products. While very good diastereoselectivities were achieved (83 - 88% d. e.) in these reactions, the material yields from reaction with the secondary alkyl iodides were low (31- 35%) due, presumably, to their decreased electrophilicity. Computer modelling studies of the enolate were carried out and support the hypothesis of endo attack by the electrophile on the enolate intermediate. These studies also indicate the possibility of coordination of the postassium cation to the endocyclic ester oxygen, thus effectively anchoring the bulky cation away from the reaction site.
- Full Text:
- Date Issued: 2000
- Authors: Klein, Rosalyn
- Date: 2000
- Subjects: Asymmetric synthesis , Alkylation , Chemical reactions
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4405 , http://hdl.handle.net/10962/d1006710 , Asymmetric synthesis , Alkylation , Chemical reactions
- Description: A novel camphor-derived hydroxy ketal 138 has been developed as a crural auxiliary, and used to prepare a series of six carboxylic esters of increasing steric bulk. The α-benzylation of this series of esters was achieved with diastereoselectivities of 59 - 83% d. e. and in 39 - 48% material yield. These results compared very favourably with those obtained in earlier studies using a regioisomeric analogue as the chiral auxiliary. Computer.modelling studies of the putative enolate intermediate has provided some insight into the possible mode of electrophilic attack at the α-carbon and the roles of the ketal protecting group and the lithium cation in these asymmetric transformations. In a related investigation, based on earlier work, a camphor-derived imino lactone has provided convenient access to α-alkyl α-amino acids, the imino lactone serving as a masked glycine equivalent. Using straight chain primary alkyl iodides [RI; R = Me, Et, Pr, Bu, CH₃(CH₂)₄ and CH₃(CH₄)₅], alkylation of the potassium enolate of the camphor-derived imino lactone was effected with 54 - 89% d.e. and in 54 - 87% material yield. Four novel alkylated derivatives were synthesised using isopropyl iodide, sec-butyl iodide and allyl iodide, the latter reagent resulting in both the monoallylated and diallylated products. While very good diastereoselectivities were achieved (83 - 88% d. e.) in these reactions, the material yields from reaction with the secondary alkyl iodides were low (31- 35%) due, presumably, to their decreased electrophilicity. Computer modelling studies of the enolate were carried out and support the hypothesis of endo attack by the electrophile on the enolate intermediate. These studies also indicate the possibility of coordination of the postassium cation to the endocyclic ester oxygen, thus effectively anchoring the bulky cation away from the reaction site.
- Full Text:
- Date Issued: 2000
Characterization of amide bond hydrolysis in novel hydantoinase-producing bacteria
- Authors: Skepu, Zoleka G
- Date: 2000
- Subjects: Amides , Hydrolysis , Hydantoin , Imides
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3911 , http://hdl.handle.net/10962/d1003970 , Amides , Hydrolysis , Hydantoin , Imides
- Description: This thesis describes a series of investigations into the amide bond-hydrolyzing activity of bacterial strains RU-KM1, RU-KM3L, RU-KM3S, and RU-OR, which were previously isolated for their ability to hydrolyze hydantoins to amino acids. The main aim of the study was to develop biotransformations with potential application in the production of enantiomerically pure amino acids and related compounds. Several compounds may be used as substrates by biocatalysts for the production of amino acids, such as hydantoins, amino nitriles, and amides. These compounds are not only important for amino acid production, but they may be used for production of other industrially important compounds, such as 2- arylpropionic acids, which are non-steroidal anti-inflammatory drugs. Thus, the ability of the above-mentioned strains to hydrolyze these substrates was investigated, with the view to utilizing the maximum potential of these biocatalysts. The compounds used as substrates in the investigation are all essentially amides. Thus, the ability of the strains to hydrolyze imides, hydantoins, and amides, was investigated. In particular, imides have a structure which is very similar to that of hydantoins, and thus it was an objective of the study to determine whether these strains could hydrolyze imides. Imidehydrolyzing activity has only recently been discovered in microorganisms. Hydantoin conversion involves a two-step hydrolysis reaction which yields, initially, an Ncarbamylamino acid intermediate, and subsequently, an "-amino acid. The hydantoinhydrolyzing enzymes of a Pseudomonas putida strain, RU-KM3S, were characterized in a crude extract preparation and reaction conditions for its biocatalytic application were optimized. The optimum conditions for conversion of 5-methylhydantoin were found to be 3 hours at 40°C, with conversion yields greater than 50% achieved. The enzymes of RU-KM3S demonstrated considerable stability, retaining 80% of their activity after incubation at 40°C for 3 hours. The activities of the enzymes were increased by the addition of a detergent to the extraction medium, suggesting that the enzymes might be membrane-bound. The results of the determination of the metal-dependence of the hydantoinase and N-carbamylase of RUKM3S suggested that these enzymes required metal ions for activity, with metal ions such as Mg²⁺, Mn²⁺, Zn²⁺, and Co²⁺ resulting in activation of the enzymes. However, Cu²⁺ and Fe²⁺ caused inactivation of these enzymes. The stereoselectivity of the enzymes was investigated, and the results suggested that the hydantoinase was non-selective, whereas the N-carbamylase was L-selective. The hydantoin substrate selectivity of RU-KM3S was compared to that of three other hydantoinase-producing bacteria, RU-KM1, RU-KM3L, and RU-OR. The four strains were able to hydrolyze all of the seven substrates tested. However, there was a difference in activity levels between crude extract preparations and whole cells, with crude extracts generally showing higher activity than whole cells, except in the case of RU-KM1. Some difference was also observed in the order of preference of substrates between whole cells and crude extracts. The preferred substrate for RU-KM1 whole cells was isopropylhydantoin, whereas the crude extract preparation preferentially hydrolyzed p-hydroxyphenylhydantoin. RU-KM3L whole cells achieved a higher conversion yield with isobutylhydantoin, whereas the crude extract achieved a higher yield with 5-t-butylhydantoin. RU-KM3S whole cells and crude extract preferentially hydrolyzed 5-n-butylhydantoin, although the yield was greater with the crude extract. The highest conversion yields were observed with RU-KM3S crude extract, with conversion yields of 71.6% and 100% for n-butylhydantoin and phydroxyphenylhydantoin, respectively.The ability of RU-KM1, RU-KM3L, and RU-KM3S to hydrolyze nitriles, initially to amides and subsequently to carboxylic acids, was investigated. These strains were demonstrated to be unable to utilize acrylonitrile, propionitrile and benzonitrile as nitrogen sources, but were able to hydrolyze acrylonitrile, propionitrile and acetonitrile, in resting cell reactions. Nitrile hydrolysis was demonstrated to be inducible in all three strains, and the enzyme system responsible for nitrile hydrolysis was proposed to be a nitrile hydratase-amidase system. Amidase activity in the four bacterial strains was investigated. The ability of RU-KM1, RUKM3L, RU-KM3S, and RU-OR to utilize amides as a nitrogen source was investigated, and the results showed that propionamide was a good nitrogen source for all four of the strains. Amide-hydrolyzing activity, by resting cells, was shown to be inducible by propionamide in all four strains. RU-KM3S demonstrated superior amide-hydrolyzing ability in that it hydrolyzed propionamide, acetamide, and acrylamide to a greater extent than the other strains. Resting cells of RU-KM1 and RU-OR were demonstrated to have the ability to hydrolyze the imide substrate, succinimide, and this imidase activity was found to be inducible. These strains were also able to utilize this imide as the sole source of nitrogen for growth, which is a novel finding, as to date, bacteria have only be reported to utilize imides as a carbon source. The identity of the enzyme system responsible for succinimide hydrolysis is not yet clear. In conclusion, the hydantoin-hydrolyzing enzymes of RU-KM3S have been shown to be possibly membrane associated, which is a novel finding that has also been proposed in three other hydantoinase-producing strains in our laboratory. This study has shown that the Ncarbamylase of RU-KM3S is L-stereoselective, which, to our knowledge, is the first report of an L-stereospecific N-carbamylase in a Pseudomonas putida. Publication of these findings is already in progress. This is the first report on the study of imide hydrolysis in either an Agrobacterium tumefaciens or a Pseudomonas sp., and publications reporting these results are in preparation.
- Full Text:
- Date Issued: 2000
- Authors: Skepu, Zoleka G
- Date: 2000
- Subjects: Amides , Hydrolysis , Hydantoin , Imides
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3911 , http://hdl.handle.net/10962/d1003970 , Amides , Hydrolysis , Hydantoin , Imides
- Description: This thesis describes a series of investigations into the amide bond-hydrolyzing activity of bacterial strains RU-KM1, RU-KM3L, RU-KM3S, and RU-OR, which were previously isolated for their ability to hydrolyze hydantoins to amino acids. The main aim of the study was to develop biotransformations with potential application in the production of enantiomerically pure amino acids and related compounds. Several compounds may be used as substrates by biocatalysts for the production of amino acids, such as hydantoins, amino nitriles, and amides. These compounds are not only important for amino acid production, but they may be used for production of other industrially important compounds, such as 2- arylpropionic acids, which are non-steroidal anti-inflammatory drugs. Thus, the ability of the above-mentioned strains to hydrolyze these substrates was investigated, with the view to utilizing the maximum potential of these biocatalysts. The compounds used as substrates in the investigation are all essentially amides. Thus, the ability of the strains to hydrolyze imides, hydantoins, and amides, was investigated. In particular, imides have a structure which is very similar to that of hydantoins, and thus it was an objective of the study to determine whether these strains could hydrolyze imides. Imidehydrolyzing activity has only recently been discovered in microorganisms. Hydantoin conversion involves a two-step hydrolysis reaction which yields, initially, an Ncarbamylamino acid intermediate, and subsequently, an "-amino acid. The hydantoinhydrolyzing enzymes of a Pseudomonas putida strain, RU-KM3S, were characterized in a crude extract preparation and reaction conditions for its biocatalytic application were optimized. The optimum conditions for conversion of 5-methylhydantoin were found to be 3 hours at 40°C, with conversion yields greater than 50% achieved. The enzymes of RU-KM3S demonstrated considerable stability, retaining 80% of their activity after incubation at 40°C for 3 hours. The activities of the enzymes were increased by the addition of a detergent to the extraction medium, suggesting that the enzymes might be membrane-bound. The results of the determination of the metal-dependence of the hydantoinase and N-carbamylase of RUKM3S suggested that these enzymes required metal ions for activity, with metal ions such as Mg²⁺, Mn²⁺, Zn²⁺, and Co²⁺ resulting in activation of the enzymes. However, Cu²⁺ and Fe²⁺ caused inactivation of these enzymes. The stereoselectivity of the enzymes was investigated, and the results suggested that the hydantoinase was non-selective, whereas the N-carbamylase was L-selective. The hydantoin substrate selectivity of RU-KM3S was compared to that of three other hydantoinase-producing bacteria, RU-KM1, RU-KM3L, and RU-OR. The four strains were able to hydrolyze all of the seven substrates tested. However, there was a difference in activity levels between crude extract preparations and whole cells, with crude extracts generally showing higher activity than whole cells, except in the case of RU-KM1. Some difference was also observed in the order of preference of substrates between whole cells and crude extracts. The preferred substrate for RU-KM1 whole cells was isopropylhydantoin, whereas the crude extract preparation preferentially hydrolyzed p-hydroxyphenylhydantoin. RU-KM3L whole cells achieved a higher conversion yield with isobutylhydantoin, whereas the crude extract achieved a higher yield with 5-t-butylhydantoin. RU-KM3S whole cells and crude extract preferentially hydrolyzed 5-n-butylhydantoin, although the yield was greater with the crude extract. The highest conversion yields were observed with RU-KM3S crude extract, with conversion yields of 71.6% and 100% for n-butylhydantoin and phydroxyphenylhydantoin, respectively.The ability of RU-KM1, RU-KM3L, and RU-KM3S to hydrolyze nitriles, initially to amides and subsequently to carboxylic acids, was investigated. These strains were demonstrated to be unable to utilize acrylonitrile, propionitrile and benzonitrile as nitrogen sources, but were able to hydrolyze acrylonitrile, propionitrile and acetonitrile, in resting cell reactions. Nitrile hydrolysis was demonstrated to be inducible in all three strains, and the enzyme system responsible for nitrile hydrolysis was proposed to be a nitrile hydratase-amidase system. Amidase activity in the four bacterial strains was investigated. The ability of RU-KM1, RUKM3L, RU-KM3S, and RU-OR to utilize amides as a nitrogen source was investigated, and the results showed that propionamide was a good nitrogen source for all four of the strains. Amide-hydrolyzing activity, by resting cells, was shown to be inducible by propionamide in all four strains. RU-KM3S demonstrated superior amide-hydrolyzing ability in that it hydrolyzed propionamide, acetamide, and acrylamide to a greater extent than the other strains. Resting cells of RU-KM1 and RU-OR were demonstrated to have the ability to hydrolyze the imide substrate, succinimide, and this imidase activity was found to be inducible. These strains were also able to utilize this imide as the sole source of nitrogen for growth, which is a novel finding, as to date, bacteria have only be reported to utilize imides as a carbon source. The identity of the enzyme system responsible for succinimide hydrolysis is not yet clear. In conclusion, the hydantoin-hydrolyzing enzymes of RU-KM3S have been shown to be possibly membrane associated, which is a novel finding that has also been proposed in three other hydantoinase-producing strains in our laboratory. This study has shown that the Ncarbamylase of RU-KM3S is L-stereoselective, which, to our knowledge, is the first report of an L-stereospecific N-carbamylase in a Pseudomonas putida. Publication of these findings is already in progress. This is the first report on the study of imide hydrolysis in either an Agrobacterium tumefaciens or a Pseudomonas sp., and publications reporting these results are in preparation.
- Full Text:
- Date Issued: 2000
Colonial photography in nineteenth century Grahamstown: an analysis of the Dr W.G. Atherstone Bequest
- Authors: Waters, Hywell George
- Date: 2000
- Subjects: Atherstone, W. G. (William Guybon), 1814-1898 Art and photography Photography -- Technique
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2426 , http://hdl.handle.net/10962/d1002222
- Description: The research for this degree comprises of a theoretical dissertationand a practicalcomponent of exhibited photographs. The theoretical research investigates the original photographic prints and glass-plate negatives taken betweenthe 1840's and 1890's, by the late Dr. W.G. Atherstone - an enthusiastic, Grahamstown amateur photographer. Dr W. G Atherstone's prints and negatives were examined by the author to deduce and establish his photographic abilities, his numerous techniques, diverse subject matter and the pictorialconstructionof his images. Selected works will be examined in order to interpret and illustrate his diverse interests and approaches towards photography. The selection of these photographs was determined by their pertinence to subject matter, and to the pictorial and historical considerations of the candidate. These issues are finally examined in relation to the candidates's own approach to photography today.
- Full Text:
- Date Issued: 2000
- Authors: Waters, Hywell George
- Date: 2000
- Subjects: Atherstone, W. G. (William Guybon), 1814-1898 Art and photography Photography -- Technique
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2426 , http://hdl.handle.net/10962/d1002222
- Description: The research for this degree comprises of a theoretical dissertationand a practicalcomponent of exhibited photographs. The theoretical research investigates the original photographic prints and glass-plate negatives taken betweenthe 1840's and 1890's, by the late Dr. W.G. Atherstone - an enthusiastic, Grahamstown amateur photographer. Dr W. G Atherstone's prints and negatives were examined by the author to deduce and establish his photographic abilities, his numerous techniques, diverse subject matter and the pictorialconstructionof his images. Selected works will be examined in order to interpret and illustrate his diverse interests and approaches towards photography. The selection of these photographs was determined by their pertinence to subject matter, and to the pictorial and historical considerations of the candidate. These issues are finally examined in relation to the candidates's own approach to photography today.
- Full Text:
- Date Issued: 2000
Computers in science teaching: a reality or dream; The role of computers in effective science education: a case of using a computer to teach colour mixing; Career oriented science education for the next millennium
- Authors: Nadarajah, Kumaravel
- Date: 2000
- Subjects: Science -- Study and teaching Computer-assisted instruction Education -- Data processing
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1460 , http://hdl.handle.net/10962/d1003341
- Description: Science education in South Africa is not improving much. Many science educators do not have appropriate science qualifications. Majority of the learners have limited facilities to learn science. In this dilemma the move to OBE may result in further substantial deterioration of science education. A possible way out is to use computers in science education to facilitate the learning process. This study was designed to investigate how computers contribute to learners’ skills development in a physics course. A series of interactive computer simulations of colour mixing and a number of closely related traditional practical activities are aimed to promote learners’ understanding of colour. It was concluded that while computer environments have greater potentialas learning tools, they also limit interactions in significant ways.
- Full Text:
- Date Issued: 2000
- Authors: Nadarajah, Kumaravel
- Date: 2000
- Subjects: Science -- Study and teaching Computer-assisted instruction Education -- Data processing
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1460 , http://hdl.handle.net/10962/d1003341
- Description: Science education in South Africa is not improving much. Many science educators do not have appropriate science qualifications. Majority of the learners have limited facilities to learn science. In this dilemma the move to OBE may result in further substantial deterioration of science education. A possible way out is to use computers in science education to facilitate the learning process. This study was designed to investigate how computers contribute to learners’ skills development in a physics course. A series of interactive computer simulations of colour mixing and a number of closely related traditional practical activities are aimed to promote learners’ understanding of colour. It was concluded that while computer environments have greater potentialas learning tools, they also limit interactions in significant ways.
- Full Text:
- Date Issued: 2000
Constitutional frameworks and democratization in Africa since independence
- Authors: Neirynck, Karim
- Date: 2000
- Subjects: Democracy -- Africa , Constitutions -- Africa , Africa -- Politics and government -- 1960-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2816 , http://hdl.handle.net/10962/d1003026 , Democracy -- Africa , Constitutions -- Africa , Africa -- Politics and government -- 1960-
- Description: The subject of this thesis is international studies, specifically a study of constitutional frameworks in Africa in the second half of the 20th century, focussing on a statistical correlation between constitutional frameworks, party systems, electoral systems and the Index of Democracy. The struggle to consolidate new democracies - especially those in Eastern Europe, Latin America and Asia - has given rise to a wide-ranging debate about the hard choices concerning democratic political institutions and political markets. According to Stepan and Skach " this literature has produced provocative hypotheses about the effects of institutions on democracy" (Stepan and Skach, 1993 : 1). It forms part of the' new institutionalism I literature in comparative politics that'holds as a premise that political democracy depends not only on economic and social conditions but also on the design of political institutions (Koelble, 1995 : 231-243). " One fundamental political-institutional question that has only received serious scholarly attention concerns the impact of different constitutional frameworks on democratic consolidation. Although the topic has been increasingly debated and discussed, little systematic cross-regional evidence [especially for our field of research: Africa] has been brought to bear on it " (Stepan and Skach, 1993 : 1-2). So far, only the book"on regime transitions in Africa written by Bratton and Van De Walle seeks to fill this empirical gap (Bratton and Van De Walle, 1997, preface xiii). In this thesis, we paid particular attention to the dichotomy between (pure) parliamentarism and (pure) presidentialism. Each type has fundamental characteristics, and for the purposes of classification these characteristics are necessary and sufficient. It was not our purpose to weigh the benefits and drawbacks of parliamentarism and presidentialism. Our intention was to report and analyse different sources of data, and we based our case exclusively on statistic correlatiohs between regime type and the record of democratic success and failure. We collected a data set about constitutional frameworks (matrix1), democracy indices (matrix2), party systems (matrix3) and election systems (matrix4). The basis for matrix 1 was the constitutions of the African countries (over time) and relevant literature. The basis for matrix 2 was the annual Freedom House ratings made by Raymond D. Gastil and others. The basis for matrix 3 and 4 was relevant literature. Once these matrices had been composed, we compared them and calculated statistic correlations. This long-dyration model allowed us to estimate whether African constitutional frameworks, party systems and electoral systems exhibit positive or negative correlation with the index of democracy.
- Full Text:
- Date Issued: 2000
- Authors: Neirynck, Karim
- Date: 2000
- Subjects: Democracy -- Africa , Constitutions -- Africa , Africa -- Politics and government -- 1960-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2816 , http://hdl.handle.net/10962/d1003026 , Democracy -- Africa , Constitutions -- Africa , Africa -- Politics and government -- 1960-
- Description: The subject of this thesis is international studies, specifically a study of constitutional frameworks in Africa in the second half of the 20th century, focussing on a statistical correlation between constitutional frameworks, party systems, electoral systems and the Index of Democracy. The struggle to consolidate new democracies - especially those in Eastern Europe, Latin America and Asia - has given rise to a wide-ranging debate about the hard choices concerning democratic political institutions and political markets. According to Stepan and Skach " this literature has produced provocative hypotheses about the effects of institutions on democracy" (Stepan and Skach, 1993 : 1). It forms part of the' new institutionalism I literature in comparative politics that'holds as a premise that political democracy depends not only on economic and social conditions but also on the design of political institutions (Koelble, 1995 : 231-243). " One fundamental political-institutional question that has only received serious scholarly attention concerns the impact of different constitutional frameworks on democratic consolidation. Although the topic has been increasingly debated and discussed, little systematic cross-regional evidence [especially for our field of research: Africa] has been brought to bear on it " (Stepan and Skach, 1993 : 1-2). So far, only the book"on regime transitions in Africa written by Bratton and Van De Walle seeks to fill this empirical gap (Bratton and Van De Walle, 1997, preface xiii). In this thesis, we paid particular attention to the dichotomy between (pure) parliamentarism and (pure) presidentialism. Each type has fundamental characteristics, and for the purposes of classification these characteristics are necessary and sufficient. It was not our purpose to weigh the benefits and drawbacks of parliamentarism and presidentialism. Our intention was to report and analyse different sources of data, and we based our case exclusively on statistic correlatiohs between regime type and the record of democratic success and failure. We collected a data set about constitutional frameworks (matrix1), democracy indices (matrix2), party systems (matrix3) and election systems (matrix4). The basis for matrix 1 was the constitutions of the African countries (over time) and relevant literature. The basis for matrix 2 was the annual Freedom House ratings made by Raymond D. Gastil and others. The basis for matrix 3 and 4 was relevant literature. Once these matrices had been composed, we compared them and calculated statistic correlations. This long-dyration model allowed us to estimate whether African constitutional frameworks, party systems and electoral systems exhibit positive or negative correlation with the index of democracy.
- Full Text:
- Date Issued: 2000
Cuba's revolutionist and anti-imperialist foreign policy in Southern Africa: the case of Angola and Namibia
- Authors: Othieno, Timothy
- Date: 2000
- Subjects: Cuba -- Foreign Relations -- Africa, Southern , Cuba -- Dependency on foreign countries -- History , Cuba -- Foreign relations -- Angola , Cuba -- Foreign relations -- Namibia , Cuba -- Politics and government
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2819 , http://hdl.handle.net/10962/d1003029 , Cuba -- Foreign Relations -- Africa, Southern , Cuba -- Dependency on foreign countries -- History , Cuba -- Foreign relations -- Angola , Cuba -- Foreign relations -- Namibia , Cuba -- Politics and government
- Description: This study examines Cuba’s role in the two southern African countries of Angola and Namibia during the Cold War period. It argues that Cuba’s ideological motivations have been embodied in the mutually reinforcing concepts of proletarian internationalism and anti-imperialism. These conceptual perspectives constitute some of the central variables that influence Cuba’s foreign policy behaviour in international relations. It is within this context that one can understand Cuba’s involvement in Southern Africa. This study also attempts to explain that Cuban foreign policy towards Africa was based on two complementary and contextual objectives namely, promoting nationalism at home and nurturing revolutionary Marxist-Leninist governments, as well as supporting anti-colonial and anti-imperialist movements abroad. For the purpose of achieving these foreign policy objectives, Cuba not only engaged in state-to-state relations with Angola and Namibia; but had cordial relations with the rest of the continent and in particular Southern Africa, which also became a direct military testing ground for Cuba’s commitment to an anti-colonial and anti-imperialist revolutionary stance. Furthermore, the thesis shows that Cuba’s relentless hatred of imperialism is rooted in its historical relationship with the United States because from the turn of the century till 1958, the Americans interfered in Cuba’s internal affairs by supporting corrupt administrations and exploited the country. These practices by the United States laid the foundation for Cuba’s anti-colonialism and antiimperialism abroad. Ultimately, this thesis shows that Cuban involvement in Angola and Namibia can be conceptualised within these contexts (anti-imperialism, anti-colonialism, proletarian internationalism and revolutionary Marxism-Leninism). The role of Cuban nationalism in the realisation of these objectives and ideals, as well as its role in perpetuating and consolidating her foreign policy is assessed in this study. This nationalism and ideals of internationalism constitutes the central idea in the Cuban revolution. Finally, this thesis asserts that Cuban motives for getting involved in the politics of Southern Africa were not motivated by economic or imperialistic reasons. Rather, the historical similarity and colonial experiences between Africa and Cuba were some of the central causal factors.
- Full Text:
- Date Issued: 2000
- Authors: Othieno, Timothy
- Date: 2000
- Subjects: Cuba -- Foreign Relations -- Africa, Southern , Cuba -- Dependency on foreign countries -- History , Cuba -- Foreign relations -- Angola , Cuba -- Foreign relations -- Namibia , Cuba -- Politics and government
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2819 , http://hdl.handle.net/10962/d1003029 , Cuba -- Foreign Relations -- Africa, Southern , Cuba -- Dependency on foreign countries -- History , Cuba -- Foreign relations -- Angola , Cuba -- Foreign relations -- Namibia , Cuba -- Politics and government
- Description: This study examines Cuba’s role in the two southern African countries of Angola and Namibia during the Cold War period. It argues that Cuba’s ideological motivations have been embodied in the mutually reinforcing concepts of proletarian internationalism and anti-imperialism. These conceptual perspectives constitute some of the central variables that influence Cuba’s foreign policy behaviour in international relations. It is within this context that one can understand Cuba’s involvement in Southern Africa. This study also attempts to explain that Cuban foreign policy towards Africa was based on two complementary and contextual objectives namely, promoting nationalism at home and nurturing revolutionary Marxist-Leninist governments, as well as supporting anti-colonial and anti-imperialist movements abroad. For the purpose of achieving these foreign policy objectives, Cuba not only engaged in state-to-state relations with Angola and Namibia; but had cordial relations with the rest of the continent and in particular Southern Africa, which also became a direct military testing ground for Cuba’s commitment to an anti-colonial and anti-imperialist revolutionary stance. Furthermore, the thesis shows that Cuba’s relentless hatred of imperialism is rooted in its historical relationship with the United States because from the turn of the century till 1958, the Americans interfered in Cuba’s internal affairs by supporting corrupt administrations and exploited the country. These practices by the United States laid the foundation for Cuba’s anti-colonialism and antiimperialism abroad. Ultimately, this thesis shows that Cuban involvement in Angola and Namibia can be conceptualised within these contexts (anti-imperialism, anti-colonialism, proletarian internationalism and revolutionary Marxism-Leninism). The role of Cuban nationalism in the realisation of these objectives and ideals, as well as its role in perpetuating and consolidating her foreign policy is assessed in this study. This nationalism and ideals of internationalism constitutes the central idea in the Cuban revolution. Finally, this thesis asserts that Cuban motives for getting involved in the politics of Southern Africa were not motivated by economic or imperialistic reasons. Rather, the historical similarity and colonial experiences between Africa and Cuba were some of the central causal factors.
- Full Text:
- Date Issued: 2000
Cumulative mild head injury in contact sport: a comparison of the cognitive profiles of rugby players and non-contact sport controls with normative data
- Authors: Bold, Lisa Clare
- Date: 2000
- Subjects: Head -- Wounds and injuries -- Psychology , Neuropsychological tests , Head -- Wounds and injuries , Sports injuries -- Psychological aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2935 , http://hdl.handle.net/10962/d1002444 , Head -- Wounds and injuries -- Psychology , Neuropsychological tests , Head -- Wounds and injuries , Sports injuries -- Psychological aspects
- Description: This study investigates the effects of cumulative mild head injury on the cognitive functioning of elite rugby players. A comprehensive battery of neuropsychological tests was administered to top national (Springbok) rugby players (n=26), national Under 21 rugby players (n= 19), and a non-contact sport control group of national hockey players (n=21). The test results of the Total Rugby group (Springbok Rugby and Under 21 Rugby players), the Under 21 Rugby group, the hockey controls, and the Total Rugby and Under 21 Rugby forward and backline players respectively, were each compared with established normative data. Results showed significant differences in the direction of a poorer performance relative to the norms for the Total Rugby and Under 21 Rugby groups, and for the Total Rugby Forwards and Under 21 Rugby Forwards, on tests sensitive to the effects of diffuse brain damage. On the other hand, the Hockey Control group and the Total Rugby Backs and Under 21 Rugby Backs tended to perform within the normal range or better than the norm on some tests. These results confirm the hypothesis that rugby players, and the forward players in particular, are at risk of adverse cognitive effects consequent on cumulative mild head injury. The theoretical implications are that the aggregate effects of multiple exposures to mild head injuries in the rugby players served to reduce their brain reserve capacities and acted as a threshold-lowering influence associated with symptom onset.
- Full Text:
- Date Issued: 2000
- Authors: Bold, Lisa Clare
- Date: 2000
- Subjects: Head -- Wounds and injuries -- Psychology , Neuropsychological tests , Head -- Wounds and injuries , Sports injuries -- Psychological aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2935 , http://hdl.handle.net/10962/d1002444 , Head -- Wounds and injuries -- Psychology , Neuropsychological tests , Head -- Wounds and injuries , Sports injuries -- Psychological aspects
- Description: This study investigates the effects of cumulative mild head injury on the cognitive functioning of elite rugby players. A comprehensive battery of neuropsychological tests was administered to top national (Springbok) rugby players (n=26), national Under 21 rugby players (n= 19), and a non-contact sport control group of national hockey players (n=21). The test results of the Total Rugby group (Springbok Rugby and Under 21 Rugby players), the Under 21 Rugby group, the hockey controls, and the Total Rugby and Under 21 Rugby forward and backline players respectively, were each compared with established normative data. Results showed significant differences in the direction of a poorer performance relative to the norms for the Total Rugby and Under 21 Rugby groups, and for the Total Rugby Forwards and Under 21 Rugby Forwards, on tests sensitive to the effects of diffuse brain damage. On the other hand, the Hockey Control group and the Total Rugby Backs and Under 21 Rugby Backs tended to perform within the normal range or better than the norm on some tests. These results confirm the hypothesis that rugby players, and the forward players in particular, are at risk of adverse cognitive effects consequent on cumulative mild head injury. The theoretical implications are that the aggregate effects of multiple exposures to mild head injuries in the rugby players served to reduce their brain reserve capacities and acted as a threshold-lowering influence associated with symptom onset.
- Full Text:
- Date Issued: 2000
Desert
- Authors: Harper, Sean Julian
- Date: 2000
- Subjects: Rawls, John, 1921-2002 , Rawls, John, 1921-2002 Theory of justice , Ethics
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2710 , http://hdl.handle.net/10962/d1002840 , Rawls, John, 1921-2002 , Rawls, John, 1921-2002 Theory of justice , Ethics
- Description: This thesis examines the idea of desert as expounded in the work of John Rawls, and some of the implications of this conception of desert for moral and political philosophy. In this work, I analyse a series of arguments against retaining this particular conception of desert.I argue that none of these arguments sufficiently diminishes the force of Rawls’ argument for desert, while many of them do state, and I argue that they are correct in doing so, that this conception of desert is dangerous for political or moral philosophy to maintain. I argue that the moral, political and legal implications of accepting this account of desert severely undermine various institutions of differential treatment, and indeed, moral assessment. I regard it as obvious that societies must, on occasion, treat members of those societies differently, for moral, as well as practical reasons. The Rawlsian account of desert, and the account of responsibility on which it rests, however, will endanger the legitimacy of such procedures. I argue further that the Rawlsian account of desert requires that differences in wealth, and inheritance of wealth, influence and privilege be diminished, if not abolished, if we are to talk of any form of desert meaningfully. I argue that this is a strength of Rawls’ account, and further that any account of desert that is true to the philosophical tradition of the concept will require similar steps to be taken. The primary aim of this thesis is to show that Rawls’ arguments against desert are serious ones, both in terms of strength and scope, and that they must be addressed. I intend to show that these arguments are founded on strong moral intuitions, and that it is plausible that these intuitions may need revision. Finally,I intend to show that desert is an important moral and political concept, and that the disciplines of moral and political philosophy will be impoverished by the absence this concept. This absence, I will argue, is a natural consequence of the acceptance of the Rawlsian arguments.
- Full Text:
- Date Issued: 2000
- Authors: Harper, Sean Julian
- Date: 2000
- Subjects: Rawls, John, 1921-2002 , Rawls, John, 1921-2002 Theory of justice , Ethics
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2710 , http://hdl.handle.net/10962/d1002840 , Rawls, John, 1921-2002 , Rawls, John, 1921-2002 Theory of justice , Ethics
- Description: This thesis examines the idea of desert as expounded in the work of John Rawls, and some of the implications of this conception of desert for moral and political philosophy. In this work, I analyse a series of arguments against retaining this particular conception of desert.I argue that none of these arguments sufficiently diminishes the force of Rawls’ argument for desert, while many of them do state, and I argue that they are correct in doing so, that this conception of desert is dangerous for political or moral philosophy to maintain. I argue that the moral, political and legal implications of accepting this account of desert severely undermine various institutions of differential treatment, and indeed, moral assessment. I regard it as obvious that societies must, on occasion, treat members of those societies differently, for moral, as well as practical reasons. The Rawlsian account of desert, and the account of responsibility on which it rests, however, will endanger the legitimacy of such procedures. I argue further that the Rawlsian account of desert requires that differences in wealth, and inheritance of wealth, influence and privilege be diminished, if not abolished, if we are to talk of any form of desert meaningfully. I argue that this is a strength of Rawls’ account, and further that any account of desert that is true to the philosophical tradition of the concept will require similar steps to be taken. The primary aim of this thesis is to show that Rawls’ arguments against desert are serious ones, both in terms of strength and scope, and that they must be addressed. I intend to show that these arguments are founded on strong moral intuitions, and that it is plausible that these intuitions may need revision. Finally,I intend to show that desert is an important moral and political concept, and that the disciplines of moral and political philosophy will be impoverished by the absence this concept. This absence, I will argue, is a natural consequence of the acceptance of the Rawlsian arguments.
- Full Text:
- Date Issued: 2000
Designing and implementing a virtual reality interaction framework
- Authors: Rorke, Michael
- Date: 2000
- Subjects: Virtual reality , Computer simulation , Human-computer interaction , Computer graphics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4623 , http://hdl.handle.net/10962/d1006491 , Virtual reality , Computer simulation , Human-computer interaction , Computer graphics
- Description: Virtual Reality offers the possibility for humans to interact in a more natural way with the computer and its applications. Currently, Virtual Reality is used mainly in the field of visualisation where 3D graphics allow users to more easily view complex sets of data or structures. The field of interaction in Virtual Reality has been largely neglected due mainly to problems with input devices and equipment costs. Recent research has aimed to overcome these interaction problems, thereby creating a usable interaction platform for Virtual Reality. This thesis presents a background into the field of interaction in Virtual Reality. It goes on to propose a generic framework for the implementation of common interaction techniques into a homogeneous application development environment. This framework adds a new layer to the standard Virtual Reality toolkit – the interaction abstraction layer, or interactor layer. This separation is in line with current HCI practices. The interactor layer is further divided into specific sections – input component, interaction component, system component, intermediaries, entities and widgets. Each of these performs a specific function, with clearly defined interfaces between the different components to promote easy objectoriented implementation of the framework. The validity of the framework is shown in comparison with accepted taxonomies in the area of Virtual Reality interaction. Thus demonstrating that the framework covers all the relevant factors involved in the field. Furthermore, the thesis describes an implementation of this framework. The implementation was completed using the Rhodes University CoRgi Virtual Reality toolkit. Several postgraduate students in the Rhodes University Computer Science Department utilised the framework implementation to develop a set of case studies. These case studies demonstrate the practical use of the framework to create useful Virtual Reality applications, as well as demonstrating the generic nature of the framework and its extensibility to be able to handle new interaction techniques. Finally, the generic nature of the framework is further demonstrated by moving it from the standard CoRgi Virtual Reality toolkit, to a distributed version of this toolkit. The distributed implementation of the framework utilises the Common Object Request Broker Architecture (CORBA) to implement the distribution of the objects in the system. Using this distributed implementation, we are able to ascertain that CORBA is useful in the field of distributed real-time Virtual Reality, even taking into account the extra overhead introduced by the additional abstraction layer. We conclude from this thesis that it is important to abstract the interaction layer from the other layers of a Virtual Reality toolkit in order to provide a consistent interface to developers. We have shown that our framework is implementable and useful in the field, making it easier for developers to include interaction in their Virtual Reality applications. Our framework is able to handle all the current aspects of interaction in Virtual Reality, as well as being general enough to implement future interaction techniques. The framework is also applicable to different Virtual Reality toolkits and development platforms, making it ideal for developing general, cross-platform interactive Virtual Reality applications.
- Full Text:
- Date Issued: 2000
- Authors: Rorke, Michael
- Date: 2000
- Subjects: Virtual reality , Computer simulation , Human-computer interaction , Computer graphics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4623 , http://hdl.handle.net/10962/d1006491 , Virtual reality , Computer simulation , Human-computer interaction , Computer graphics
- Description: Virtual Reality offers the possibility for humans to interact in a more natural way with the computer and its applications. Currently, Virtual Reality is used mainly in the field of visualisation where 3D graphics allow users to more easily view complex sets of data or structures. The field of interaction in Virtual Reality has been largely neglected due mainly to problems with input devices and equipment costs. Recent research has aimed to overcome these interaction problems, thereby creating a usable interaction platform for Virtual Reality. This thesis presents a background into the field of interaction in Virtual Reality. It goes on to propose a generic framework for the implementation of common interaction techniques into a homogeneous application development environment. This framework adds a new layer to the standard Virtual Reality toolkit – the interaction abstraction layer, or interactor layer. This separation is in line with current HCI practices. The interactor layer is further divided into specific sections – input component, interaction component, system component, intermediaries, entities and widgets. Each of these performs a specific function, with clearly defined interfaces between the different components to promote easy objectoriented implementation of the framework. The validity of the framework is shown in comparison with accepted taxonomies in the area of Virtual Reality interaction. Thus demonstrating that the framework covers all the relevant factors involved in the field. Furthermore, the thesis describes an implementation of this framework. The implementation was completed using the Rhodes University CoRgi Virtual Reality toolkit. Several postgraduate students in the Rhodes University Computer Science Department utilised the framework implementation to develop a set of case studies. These case studies demonstrate the practical use of the framework to create useful Virtual Reality applications, as well as demonstrating the generic nature of the framework and its extensibility to be able to handle new interaction techniques. Finally, the generic nature of the framework is further demonstrated by moving it from the standard CoRgi Virtual Reality toolkit, to a distributed version of this toolkit. The distributed implementation of the framework utilises the Common Object Request Broker Architecture (CORBA) to implement the distribution of the objects in the system. Using this distributed implementation, we are able to ascertain that CORBA is useful in the field of distributed real-time Virtual Reality, even taking into account the extra overhead introduced by the additional abstraction layer. We conclude from this thesis that it is important to abstract the interaction layer from the other layers of a Virtual Reality toolkit in order to provide a consistent interface to developers. We have shown that our framework is implementable and useful in the field, making it easier for developers to include interaction in their Virtual Reality applications. Our framework is able to handle all the current aspects of interaction in Virtual Reality, as well as being general enough to implement future interaction techniques. The framework is also applicable to different Virtual Reality toolkits and development platforms, making it ideal for developing general, cross-platform interactive Virtual Reality applications.
- Full Text:
- Date Issued: 2000
Designing and making a difference: an exploration of technology education for rural school teachers
- Authors: Schäfer, Marc
- Date: 2000
- Subjects: Technology -- Study and teaching -- South Africa -- Eastern Cape Technology -- Study and teaching -- South Africa Rural schools -- South Africa -- Eastern Cape Education, Rural -- South Africa Winterberg schools trust
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1491 , http://hdl.handle.net/10962/d1003372
- Description: This qualitative study focused on a Technology Education programme for farm school teachers in the Eastern Cape province of South Africa. These teachers were faced with the challenge of incorporating Technology Education into their curriculum. The study was conducted within the context of an investigation into the conceptual nature of technology and an exploration of the theoretical underpinnings of Technology Education within both the international and South African context. Technology Education is being introduced into the South African curriculum against a background of educational transformation and the building of capacity to solve real life problems. This calls for a curriculum that will empower learners to be innovative, creative and skilled problem solvers. The introduction and incorporation of Technoiogy Education into the school curriculum poses a formidable challenge to farm schools in particular. Their unique history of neglect and legacy of underqualified teachers has made the introduction of any curriculum innovation process very difficult and challenging. This study analyses how an introductory Technology Education programme for farm school teachers in the Winterberg area of the Eastern Cape impacted~ on the teachers' professional and personal lives. It shows the importance of developing teclpological skills in conjunction with life skills in cO.ntributing to the empowerment, both in the work place and in the wider context, of rural school teachers. It highlights the need for supportive in-service education programmes and strengthens the argument for an integrative and mulitidisciplinary approach to the introduction of Technology Education in farm schools. Data was collected by means of questionnaires, interviews and photographs.
- Full Text:
- Date Issued: 2000
- Authors: Schäfer, Marc
- Date: 2000
- Subjects: Technology -- Study and teaching -- South Africa -- Eastern Cape Technology -- Study and teaching -- South Africa Rural schools -- South Africa -- Eastern Cape Education, Rural -- South Africa Winterberg schools trust
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1491 , http://hdl.handle.net/10962/d1003372
- Description: This qualitative study focused on a Technology Education programme for farm school teachers in the Eastern Cape province of South Africa. These teachers were faced with the challenge of incorporating Technology Education into their curriculum. The study was conducted within the context of an investigation into the conceptual nature of technology and an exploration of the theoretical underpinnings of Technology Education within both the international and South African context. Technology Education is being introduced into the South African curriculum against a background of educational transformation and the building of capacity to solve real life problems. This calls for a curriculum that will empower learners to be innovative, creative and skilled problem solvers. The introduction and incorporation of Technoiogy Education into the school curriculum poses a formidable challenge to farm schools in particular. Their unique history of neglect and legacy of underqualified teachers has made the introduction of any curriculum innovation process very difficult and challenging. This study analyses how an introductory Technology Education programme for farm school teachers in the Winterberg area of the Eastern Cape impacted~ on the teachers' professional and personal lives. It shows the importance of developing teclpological skills in conjunction with life skills in cO.ntributing to the empowerment, both in the work place and in the wider context, of rural school teachers. It highlights the need for supportive in-service education programmes and strengthens the argument for an integrative and mulitidisciplinary approach to the introduction of Technology Education in farm schools. Data was collected by means of questionnaires, interviews and photographs.
- Full Text:
- Date Issued: 2000
Development of the components of a low cost, distributed facial virtual conferencing system
- Authors: Panagou, Soterios
- Date: 2000 , 2011-11-10
- Subjects: Virtual computer systems , Virtual reality , Computer conferencing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4622 , http://hdl.handle.net/10962/d1006490 , Virtual computer systems , Virtual reality , Computer conferencing
- Description: This thesis investigates the development of a low cost, component based facial virtual conferencing system. The design is decomposed into an encoding phase and a decoding phase, which communicate with each other via a network connection. The encoding phase is composed of three components: model acquisition (which handles avatar generation), pose estimation and expression analysis. Audio is not considered part of the encoding and decoding process, and as such is not evaluated. The model acquisition component is implemented using a visual hull reconstruction algorithm that is able to reconstruct real-world objects using only sets of images of the object as input. The object to be reconstructed is assumed to lie in a bounding volume of voxels. The reconstruction process involves the following stages: - Space carving for basic shape extraction; - Isosurface extraction to remove voxels not part of the surface of the reconstruction; - Mesh connection to generate a closed, connected polyhedral mesh; - Texture generation. Texturing is achieved by Gouraud shading the reconstruction with a vertex colour map; - Mesh decimation to simplify the object. The original algorithm has complexity O(n), but suffers from an inability to reconstruct concave surfaces that do not form part of the visual hull of the object. A novel extension to this algorithm based on Normalised Cross Correlation (NCC) is proposed to overcome this problem. An extension to speed up traditional NCC evaluations is proposed which reduces the NCC search space from a 2D search problem down to a single evaluation. Pose estimation and expression analysis are performed by tracking six fiducial points on the face of a subject. A tracking algorithm is developed that uses Normalised Cross Correlation to facilitate robust tracking that is invariant to changing lighting conditions, rotations and scaling. Pose estimation involves the recovery of the head position and orientation through the tracking of the triangle formed by the subject's eyebrows and nose tip. A rule-based evaluation of points that are tracked around the subject's mouth forms the basis of the expression analysis. A user assisted feedback loop and caching mechanism is used to overcome tracking errors due to fast motion or occlusions. The NCC tracker is shown to achieve a tracking performance of 10 fps when tracking the six fiducial points. The decoding phase is divided into 3 tasks, namely: avatar movement, expression generation and expression management. Avatar movement is implemented using the base VR system. Expression generation is facilitated using a Vertex Interpolation Deformation method. A weighting system is proposed for expression management. Its function is to gradually transform from one expression to the next. The use of the vertex interpolation method allows real-time deformations of the avatar representation, achieving 16 fps when applied to a model consisting of 7500 vertices. An Expression Parameter Lookup Table (EPLT) facilitates an independent mapping between the two phases. It defines a list of generic expressions that are known to the system and associates an Expression ID with each one. For each generic expression, it relates the expression analysis rules for any subject with the expression generation parameters for any avatar model. The result is that facial expression replication between any subject and avatar combination can be performed by transferring only the Expression ID from the encoder application to the decoder application. The ideas developed in the thesis are demonstrated in an implementation using the CoRgi Virtual Reality system. It is shown that the virtual-conferencing application based on this design requires only a bandwidth of 2 Kbps. , Adobe Acrobat Pro 9.4.6 , Adobe Acrobat 9.46 Paper Capture Plug-in
- Full Text:
- Date Issued: 2000
- Authors: Panagou, Soterios
- Date: 2000 , 2011-11-10
- Subjects: Virtual computer systems , Virtual reality , Computer conferencing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4622 , http://hdl.handle.net/10962/d1006490 , Virtual computer systems , Virtual reality , Computer conferencing
- Description: This thesis investigates the development of a low cost, component based facial virtual conferencing system. The design is decomposed into an encoding phase and a decoding phase, which communicate with each other via a network connection. The encoding phase is composed of three components: model acquisition (which handles avatar generation), pose estimation and expression analysis. Audio is not considered part of the encoding and decoding process, and as such is not evaluated. The model acquisition component is implemented using a visual hull reconstruction algorithm that is able to reconstruct real-world objects using only sets of images of the object as input. The object to be reconstructed is assumed to lie in a bounding volume of voxels. The reconstruction process involves the following stages: - Space carving for basic shape extraction; - Isosurface extraction to remove voxels not part of the surface of the reconstruction; - Mesh connection to generate a closed, connected polyhedral mesh; - Texture generation. Texturing is achieved by Gouraud shading the reconstruction with a vertex colour map; - Mesh decimation to simplify the object. The original algorithm has complexity O(n), but suffers from an inability to reconstruct concave surfaces that do not form part of the visual hull of the object. A novel extension to this algorithm based on Normalised Cross Correlation (NCC) is proposed to overcome this problem. An extension to speed up traditional NCC evaluations is proposed which reduces the NCC search space from a 2D search problem down to a single evaluation. Pose estimation and expression analysis are performed by tracking six fiducial points on the face of a subject. A tracking algorithm is developed that uses Normalised Cross Correlation to facilitate robust tracking that is invariant to changing lighting conditions, rotations and scaling. Pose estimation involves the recovery of the head position and orientation through the tracking of the triangle formed by the subject's eyebrows and nose tip. A rule-based evaluation of points that are tracked around the subject's mouth forms the basis of the expression analysis. A user assisted feedback loop and caching mechanism is used to overcome tracking errors due to fast motion or occlusions. The NCC tracker is shown to achieve a tracking performance of 10 fps when tracking the six fiducial points. The decoding phase is divided into 3 tasks, namely: avatar movement, expression generation and expression management. Avatar movement is implemented using the base VR system. Expression generation is facilitated using a Vertex Interpolation Deformation method. A weighting system is proposed for expression management. Its function is to gradually transform from one expression to the next. The use of the vertex interpolation method allows real-time deformations of the avatar representation, achieving 16 fps when applied to a model consisting of 7500 vertices. An Expression Parameter Lookup Table (EPLT) facilitates an independent mapping between the two phases. It defines a list of generic expressions that are known to the system and associates an Expression ID with each one. For each generic expression, it relates the expression analysis rules for any subject with the expression generation parameters for any avatar model. The result is that facial expression replication between any subject and avatar combination can be performed by transferring only the Expression ID from the encoder application to the decoder application. The ideas developed in the thesis are demonstrated in an implementation using the CoRgi Virtual Reality system. It is shown that the virtual-conferencing application based on this design requires only a bandwidth of 2 Kbps. , Adobe Acrobat Pro 9.4.6 , Adobe Acrobat 9.46 Paper Capture Plug-in
- Full Text:
- Date Issued: 2000