LTSP DNS round robin clusters: green technology access enablers for telecommunication services in marginalised communities
- Siebörger, Ingrid, Terzoli, Alfredo, Hodgkinson-Williams, Cheryl
- Authors: Siebörger, Ingrid , Terzoli, Alfredo , Hodgkinson-Williams, Cheryl
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428437 , vital:72511 , https://d1wqtxts1xzle7.cloudfront.net/75984640/177-libre.pdf?1639074275=andresponse-content-disposi-tion=inline%3B+filename%3DLTSP_DNS_Round_Robin_Clusters_Green_Tech.pdfandExpires=1714912779andSignature=Gmd52OTCvGmiKhiFiQH~rrfp6lSPbp7glndLPn7V4Jy5yt7lU-eToE4IPxr7lDQQOdUW348nkXIMgYHnXkWjWl7nYBM7hlluxJGd15oKbpifvTofHVVEB-kOLbz0caOrAodnS~eMHdebRQOumKSAHPGQkqem756vbw0KV7bhmFQ0TUN-vsVeBoH5ftfg7s355Oh9EZCQhZu~~P0AWzlSRnMTH~6vpj3EKvp7P4gy55oISZ~207VFFFZidb90aoP7JWehRYjRqn3Tk19A6nwm4o9U-wc9Dz1MrCy-YfbqOxdNulQh4bti2WI7DA6C3Q8TMCbtqnZskXQYsIzfEianS~gw__andKey-Pair-Id=APKAJLOHF5GGSLRBV4ZA
- Description: Rural development is seen as a priority in South Africa; information and knowledge are key strategic resources for social and economic develop-ment. Information Communication Technologies (ICTs) are seen as im-portant tools in rural development, assisting in enabling change through economic development. In rural areas where ICT infrastructure is being expanded and deployed there is a need to provide appropriate technolo-gies that support sustainability and meet the needs of the local communi-ty. In this paper we argue that the use of Linux Terminal Server Project (LTSP) cluster servers are appropriate technologies for use in computer laboratory environments for relatively inexpensive access to technologies by schools and local communities in rural areas. Typically LTSP clusters are deployed when there is a need to support 100s or 1000s of comput-ers, however, we argue that by reusing recycled (older) desktop or server computers as cluster servers could lower the entry level costs of LTSP computing while maximising the use of available resources. The paper details the configuration of a Domain Name System (DNS) round robin cluster solution together with initial testing and results. It is suggested that LTSP cluster solutions, and the DNS round robin implementation, show promise for use in providing access technologies to rural communities and schools.
- Full Text:
- Date Issued: 2011
- Authors: Siebörger, Ingrid , Terzoli, Alfredo , Hodgkinson-Williams, Cheryl
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428437 , vital:72511 , https://d1wqtxts1xzle7.cloudfront.net/75984640/177-libre.pdf?1639074275=andresponse-content-disposi-tion=inline%3B+filename%3DLTSP_DNS_Round_Robin_Clusters_Green_Tech.pdfandExpires=1714912779andSignature=Gmd52OTCvGmiKhiFiQH~rrfp6lSPbp7glndLPn7V4Jy5yt7lU-eToE4IPxr7lDQQOdUW348nkXIMgYHnXkWjWl7nYBM7hlluxJGd15oKbpifvTofHVVEB-kOLbz0caOrAodnS~eMHdebRQOumKSAHPGQkqem756vbw0KV7bhmFQ0TUN-vsVeBoH5ftfg7s355Oh9EZCQhZu~~P0AWzlSRnMTH~6vpj3EKvp7P4gy55oISZ~207VFFFZidb90aoP7JWehRYjRqn3Tk19A6nwm4o9U-wc9Dz1MrCy-YfbqOxdNulQh4bti2WI7DA6C3Q8TMCbtqnZskXQYsIzfEianS~gw__andKey-Pair-Id=APKAJLOHF5GGSLRBV4ZA
- Description: Rural development is seen as a priority in South Africa; information and knowledge are key strategic resources for social and economic develop-ment. Information Communication Technologies (ICTs) are seen as im-portant tools in rural development, assisting in enabling change through economic development. In rural areas where ICT infrastructure is being expanded and deployed there is a need to provide appropriate technolo-gies that support sustainability and meet the needs of the local communi-ty. In this paper we argue that the use of Linux Terminal Server Project (LTSP) cluster servers are appropriate technologies for use in computer laboratory environments for relatively inexpensive access to technologies by schools and local communities in rural areas. Typically LTSP clusters are deployed when there is a need to support 100s or 1000s of comput-ers, however, we argue that by reusing recycled (older) desktop or server computers as cluster servers could lower the entry level costs of LTSP computing while maximising the use of available resources. The paper details the configuration of a Domain Name System (DNS) round robin cluster solution together with initial testing and results. It is suggested that LTSP cluster solutions, and the DNS round robin implementation, show promise for use in providing access technologies to rural communities and schools.
- Full Text:
- Date Issued: 2011
Lumberjacks and hoodrats: negotiating subject positions of lesbian representation in two South African television programmes
- Authors: Donaldson, Natalie
- Date: 2011
- Subjects: Lesbianism on television -- Research -- South Africa , Lesbians -- Research -- South Africa , Gay rights -- Research -- South Africa , Television actors and actresses -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:2964 , http://hdl.handle.net/10962/d1002473 , Lesbianism on television -- Research -- South Africa , Lesbians -- Research -- South Africa , Gay rights -- Research -- South Africa , Television actors and actresses -- Research -- South Africa
- Description: With the inclusion of sexual orientation in the Equality clause of the post-Apartheid constitution which demands equal rights and protection for all individuals regardless of sexual orientation, South Africa has been praised as one of the most liberal countries in the world. Because of this legal equality, gay and lesbian experiences have become a lot more visible in every day South African lives. This includes visibility in South African television programmes and film. Today, a number of South African produced television programmes have included at least one lesbian character in their storyline and many LGBTIQ activist organisations have deemed this increased visibility as a positive step for LGBTIQ rights. However, discriminatory discourses such as same-sex sexualities as 'un-African ' and unnatural, which often result in brutal hate crimes against LGBTIQ individuals (such as corrective rape), contribute to the social and cultural intolerance of same-sex sexualities. South African research into the lives of lesbian women has often related lesbian experience to that of gay men or has focused on lesbian women as victims of corrective rape and oppressive practices at the hands of the dominant heteronormative culture. This research was a discursive reception study, using three focus group discussions with self-identified lesbian audiences (black and white). The study explored how this audience received (interpreted/talked about) the available fictional representations of 'black' lesbian women and 'white' lesbian women in three clips from two South African television programmes, Society and The Mating Game. Using Wetherell's (1998) critical discursive psychology approach, this research focused on examining the 1) Subject positions made available in/by these representations; 2) Interpretive repertoires used by the audience in appropriating and/or negotiating and/or reSisting these subject positions; and 3) Ideological dilemmas experienced by participants in this negotiation process. The predominant subject positions made available in these representations were differentiated according to binary racial categories of white lesbian women and black lesbian women. For example, participants positioned white lesbian women as "lumberjacks" and "tomboys" while black lesbian women were positioned as "township lesbians" and "hood rats". In working with these subject positions, participants drew on interpretative repertoires of othering and otherness as well as interpretative repertoires of survival. In negotiating with these subject positions and others found in the discussions, ideological dilemmas often arose when participants found themselves having to draw on interpretative repertoires which extend from a heteronormative discourse. These kinds of interpretative repertoires included religion, nature, and compromise which contradicted and created a troubled position when used in relation to the participants' lesbian sexualities. Therefore, when the ideological dilemma and troubled position became apparent, participants had to work to repair the troubled position by justifying their use of these heteronormative interpretative repertoires.
- Full Text:
- Date Issued: 2011
- Authors: Donaldson, Natalie
- Date: 2011
- Subjects: Lesbianism on television -- Research -- South Africa , Lesbians -- Research -- South Africa , Gay rights -- Research -- South Africa , Television actors and actresses -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:2964 , http://hdl.handle.net/10962/d1002473 , Lesbianism on television -- Research -- South Africa , Lesbians -- Research -- South Africa , Gay rights -- Research -- South Africa , Television actors and actresses -- Research -- South Africa
- Description: With the inclusion of sexual orientation in the Equality clause of the post-Apartheid constitution which demands equal rights and protection for all individuals regardless of sexual orientation, South Africa has been praised as one of the most liberal countries in the world. Because of this legal equality, gay and lesbian experiences have become a lot more visible in every day South African lives. This includes visibility in South African television programmes and film. Today, a number of South African produced television programmes have included at least one lesbian character in their storyline and many LGBTIQ activist organisations have deemed this increased visibility as a positive step for LGBTIQ rights. However, discriminatory discourses such as same-sex sexualities as 'un-African ' and unnatural, which often result in brutal hate crimes against LGBTIQ individuals (such as corrective rape), contribute to the social and cultural intolerance of same-sex sexualities. South African research into the lives of lesbian women has often related lesbian experience to that of gay men or has focused on lesbian women as victims of corrective rape and oppressive practices at the hands of the dominant heteronormative culture. This research was a discursive reception study, using three focus group discussions with self-identified lesbian audiences (black and white). The study explored how this audience received (interpreted/talked about) the available fictional representations of 'black' lesbian women and 'white' lesbian women in three clips from two South African television programmes, Society and The Mating Game. Using Wetherell's (1998) critical discursive psychology approach, this research focused on examining the 1) Subject positions made available in/by these representations; 2) Interpretive repertoires used by the audience in appropriating and/or negotiating and/or reSisting these subject positions; and 3) Ideological dilemmas experienced by participants in this negotiation process. The predominant subject positions made available in these representations were differentiated according to binary racial categories of white lesbian women and black lesbian women. For example, participants positioned white lesbian women as "lumberjacks" and "tomboys" while black lesbian women were positioned as "township lesbians" and "hood rats". In working with these subject positions, participants drew on interpretative repertoires of othering and otherness as well as interpretative repertoires of survival. In negotiating with these subject positions and others found in the discussions, ideological dilemmas often arose when participants found themselves having to draw on interpretative repertoires which extend from a heteronormative discourse. These kinds of interpretative repertoires included religion, nature, and compromise which contradicted and created a troubled position when used in relation to the participants' lesbian sexualities. Therefore, when the ideological dilemma and troubled position became apparent, participants had to work to repair the troubled position by justifying their use of these heteronormative interpretative repertoires.
- Full Text:
- Date Issued: 2011
Macrofaunal community structure in the littoral zone of a freshwater-deprived, permanently open Eastern Cape estuary
- Henninger, Tony O, Froneman, P William
- Authors: Henninger, Tony O , Froneman, P William
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443954 , vital:74174 , https://doi.org/10.1080/15627020.2011.11407500
- Description: Spatial patterns in the macrofauna community structure within four distinct zones of the permanently open, freshwater-deprived Kariega Estuary on the southeastern coastline of southern Africa were investigated in March–May 2010. The zones within the littoral zone comprised a band of Zostera capensis (Setchell) exposed at spring low tide and comprising Zone I; a band of mud or sand, lacking vegetation, corresponded to Zone II; stands of Spartina maritima (Curtis) formed Zone III and a belt of Sarcocornia perennis (Miller) constituted Zone IV.
- Full Text:
- Date Issued: 2011
- Authors: Henninger, Tony O , Froneman, P William
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443954 , vital:74174 , https://doi.org/10.1080/15627020.2011.11407500
- Description: Spatial patterns in the macrofauna community structure within four distinct zones of the permanently open, freshwater-deprived Kariega Estuary on the southeastern coastline of southern Africa were investigated in March–May 2010. The zones within the littoral zone comprised a band of Zostera capensis (Setchell) exposed at spring low tide and comprising Zone I; a band of mud or sand, lacking vegetation, corresponded to Zone II; stands of Spartina maritima (Curtis) formed Zone III and a belt of Sarcocornia perennis (Miller) constituted Zone IV.
- Full Text:
- Date Issued: 2011
Macrophytes as indicators of physico-chemical factors in South African Estuaries
- Authors: Bezuidenhout, Chantel
- Date: 2011
- Subjects: Estuarine ecology -- South Africa , Aquatic plants -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10597 , http://hdl.handle.net/10948/1387 , Estuarine ecology -- South Africa , Aquatic plants -- South Africa
- Description: This study investigated the response of macrophytes to physico-chemical factors in seven South African estuaries and showed that dominant salt marsh species that occur in different estuaries respond to the same environmental factors. The most important variables influencing distribution were elevation, water level, sediment- and groundwater electrical conductivity and depth to the water table. In permanently open estuaries (Kromme and Olifants) transect surveys identified three distinct vegetation zones i.e. submerged macrophytes, intertidal salt marsh and supratidal salt marsh. In the Kromme Estuary intertidal salt marsh (81.2 ha) covered extensive areas, whereas supratidal (143 ha) and floodplain (797.1 ha) salt marsh were dominant in the Olifants Estuary. Transect surveys identified four distinct vegetation zones (submerged macrophytes, intertidal salt marsh, supratidal salt marsh and reeds and sedges) in the temporarily open/closed estuaries (Mngazi, Great Brak, East Kleinemonde and Seekoei estuaries), although all zones did not occur in all of the estuaries sampled. In the Mngazi Estuary reeds and sedges (1.09 ha) covered extensive areas (no submerged or salt marsh vegetation was present), whereas salt marsh (Great Brak 24.45 ha, East Kleinemonde 17.44 ha and Seekoei 12.9 ha) vegetation was dominant in the other estuaries. Despite the geographic differences, environmental factors influencing macrophyte distribution were similar in all estuaries. Canonical Correspondence Analysis showed that vegetation distribution was significantly affected by elevation, groundwater and sediment electrical conductivity and depth to groundwater. Supratidal species were associated with a greater depth to groundwater (1.2 ± 0.04 m; n = 153) compared to intertidal species (0.5 ± 0.01 m; n = 361). Correlation analysis showed that water level and rainfall were correlated with groundwater electrical conductivity in the lower and upper intertidal zones for all the estuaries sampled. These data indicate the influence of the estuary channel on the physico-chemical conditions of the salt marsh. Low rainfall (16 ± 3.3 mm per annum) in the Olifants Estuary (30-100 mS cm-1) and lack of freshwater flooding in the Kromme Estuary (42-115 mS cm-1) have resulted in high sediment electrical conductivity by comparison with the other estuaries sampled. In the Orange River Estuary approximately 70 ha of salt marsh have been lost through the building of a causeway and flood control levees. Even though salt marsh vegetation can tolerate hypersaline sediments by using the less saline water table, the groundwater at the Orange River Estuary was too saline (avg. of 90.3 ± 6.55 mS cm-1, n = 38) to be of use to the dominant floodplain species, Sarcocornia pillansii. Freshwater inflow to estuaries is important in maintaining longitudinal salinity gradients and reducing hypersaline conditions. In the Olifants Estuary and the Orange River Estuary where supratidal salt marsh is dominant, freshwater inflow is important in raising the water level and maintaining the depth to groundwater and salinity. Lack of freshwater inflow to the Kromme Estuary has highlighted the importance of rainfall in maintaining sediment salinity within acceptable ranges for the salt marsh. Macrophytes are relatively good indicators of physico-chemical factors in estuaries. From an understanding of the response of specific species to environmental variables, ecological water requirements can be set and sensitive areas can be rehabilitated.
- Full Text:
- Date Issued: 2011
- Authors: Bezuidenhout, Chantel
- Date: 2011
- Subjects: Estuarine ecology -- South Africa , Aquatic plants -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10597 , http://hdl.handle.net/10948/1387 , Estuarine ecology -- South Africa , Aquatic plants -- South Africa
- Description: This study investigated the response of macrophytes to physico-chemical factors in seven South African estuaries and showed that dominant salt marsh species that occur in different estuaries respond to the same environmental factors. The most important variables influencing distribution were elevation, water level, sediment- and groundwater electrical conductivity and depth to the water table. In permanently open estuaries (Kromme and Olifants) transect surveys identified three distinct vegetation zones i.e. submerged macrophytes, intertidal salt marsh and supratidal salt marsh. In the Kromme Estuary intertidal salt marsh (81.2 ha) covered extensive areas, whereas supratidal (143 ha) and floodplain (797.1 ha) salt marsh were dominant in the Olifants Estuary. Transect surveys identified four distinct vegetation zones (submerged macrophytes, intertidal salt marsh, supratidal salt marsh and reeds and sedges) in the temporarily open/closed estuaries (Mngazi, Great Brak, East Kleinemonde and Seekoei estuaries), although all zones did not occur in all of the estuaries sampled. In the Mngazi Estuary reeds and sedges (1.09 ha) covered extensive areas (no submerged or salt marsh vegetation was present), whereas salt marsh (Great Brak 24.45 ha, East Kleinemonde 17.44 ha and Seekoei 12.9 ha) vegetation was dominant in the other estuaries. Despite the geographic differences, environmental factors influencing macrophyte distribution were similar in all estuaries. Canonical Correspondence Analysis showed that vegetation distribution was significantly affected by elevation, groundwater and sediment electrical conductivity and depth to groundwater. Supratidal species were associated with a greater depth to groundwater (1.2 ± 0.04 m; n = 153) compared to intertidal species (0.5 ± 0.01 m; n = 361). Correlation analysis showed that water level and rainfall were correlated with groundwater electrical conductivity in the lower and upper intertidal zones for all the estuaries sampled. These data indicate the influence of the estuary channel on the physico-chemical conditions of the salt marsh. Low rainfall (16 ± 3.3 mm per annum) in the Olifants Estuary (30-100 mS cm-1) and lack of freshwater flooding in the Kromme Estuary (42-115 mS cm-1) have resulted in high sediment electrical conductivity by comparison with the other estuaries sampled. In the Orange River Estuary approximately 70 ha of salt marsh have been lost through the building of a causeway and flood control levees. Even though salt marsh vegetation can tolerate hypersaline sediments by using the less saline water table, the groundwater at the Orange River Estuary was too saline (avg. of 90.3 ± 6.55 mS cm-1, n = 38) to be of use to the dominant floodplain species, Sarcocornia pillansii. Freshwater inflow to estuaries is important in maintaining longitudinal salinity gradients and reducing hypersaline conditions. In the Olifants Estuary and the Orange River Estuary where supratidal salt marsh is dominant, freshwater inflow is important in raising the water level and maintaining the depth to groundwater and salinity. Lack of freshwater inflow to the Kromme Estuary has highlighted the importance of rainfall in maintaining sediment salinity within acceptable ranges for the salt marsh. Macrophytes are relatively good indicators of physico-chemical factors in estuaries. From an understanding of the response of specific species to environmental variables, ecological water requirements can be set and sensitive areas can be rehabilitated.
- Full Text:
- Date Issued: 2011
Maintenance of university facilities in developing countries
- Authors: Bowazi, Kenneth Mtunduwatha
- Date: 2011
- Subjects: College facilities -- Developing countries , Educational planning -- Developing countries
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9723 , http://hdl.handle.net/10948/d1008472 , College facilities -- Developing countries , Educational planning -- Developing countries
- Description: Universities in developing countries are deteriorating physically due to lack of planned maintenance, lack of maintenance policies in the institutions, lack of up-to-date security system, and also lack of qualified personnel at decision-making level. Lack of planning leads to reactive maintenance. It also leads to unbudgeted expenditure and has an impact on the amount of money allocated to maintenance which results in unavailability of funds to carry out maintenance duties. Institutions which have no maintenance policy lack guidelines to follow when a maintenance problem arises. Most personnel in charge of maintenance are junior management or at supervisory level as a result they are not part of middle management that strategically directs the organisation. Most of the decisions made at supervisory scale are easily overruled at management level where the maintenance manager is not present during meetings to motivate maintenance cases. Lack of efficient security also allows vandalism to rise which contributes to the deterioration of facilities. Universities lack creativity and cost management skills to raise its own funds to supplement the maintenance budget, which is largely funded by the government. This study recommends employment of built environment professionals in decision-making positions. It also recommends that organizations should have a maintenance policy in place. Investment should be made in good security systems and management of the facilities should include income generating activities that could subsidise the maintenance budget.
- Full Text:
- Date Issued: 2011
- Authors: Bowazi, Kenneth Mtunduwatha
- Date: 2011
- Subjects: College facilities -- Developing countries , Educational planning -- Developing countries
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9723 , http://hdl.handle.net/10948/d1008472 , College facilities -- Developing countries , Educational planning -- Developing countries
- Description: Universities in developing countries are deteriorating physically due to lack of planned maintenance, lack of maintenance policies in the institutions, lack of up-to-date security system, and also lack of qualified personnel at decision-making level. Lack of planning leads to reactive maintenance. It also leads to unbudgeted expenditure and has an impact on the amount of money allocated to maintenance which results in unavailability of funds to carry out maintenance duties. Institutions which have no maintenance policy lack guidelines to follow when a maintenance problem arises. Most personnel in charge of maintenance are junior management or at supervisory level as a result they are not part of middle management that strategically directs the organisation. Most of the decisions made at supervisory scale are easily overruled at management level where the maintenance manager is not present during meetings to motivate maintenance cases. Lack of efficient security also allows vandalism to rise which contributes to the deterioration of facilities. Universities lack creativity and cost management skills to raise its own funds to supplement the maintenance budget, which is largely funded by the government. This study recommends employment of built environment professionals in decision-making positions. It also recommends that organizations should have a maintenance policy in place. Investment should be made in good security systems and management of the facilities should include income generating activities that could subsidise the maintenance budget.
- Full Text:
- Date Issued: 2011
Male and female cardiovascular risk in an urban, black working population
- Authors: Jackson, Lindsay May
- Date: 2011
- Subjects: Cardiovascular system -- Diseases -- South Africa -- Grahamstown , Obesity -- South Africa -- Grahamstown , Hypertension -- South Africa -- Grahamstown , Hypercholesteremia -- South Africa -- Grahamstown , Diabetes -- South Africa -- Grahamstown , Lifestyles -- Health aspects -- South Africa -- Grahamstown , Health behavior -- South Africa -- Grahamstown , Health attitudes -- South Africa -- Grahamstown , Black people -- South Africa -- Grahamstown -- Health and hygiene
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5127 , http://hdl.handle.net/10962/d1005205 , Cardiovascular system -- Diseases -- South Africa -- Grahamstown , Obesity -- South Africa -- Grahamstown , Hypertension -- South Africa -- Grahamstown , Hypercholesteremia -- South Africa -- Grahamstown , Diabetes -- South Africa -- Grahamstown , Lifestyles -- Health aspects -- South Africa -- Grahamstown , Health behavior -- South Africa -- Grahamstown , Health attitudes -- South Africa -- Grahamstown , Black people -- South Africa -- Grahamstown -- Health and hygiene
- Description: The aim of this research project was to assess and compare cardiovascular disease (CVD) risk in black males and females from an urban, working population in the Makana (Grahamstown) region of the Eastern Cape, South Africa. Two-hundred and ninety one individuals (males: n = 143, females: n = 148) with a mean age of 42.6 (±8.1) years were voluntarily recruited from the greater urban Makana (Grahamstown) area. Eight Cardiovascular disease (CVD) risks were assessed: stature and mass were obtained in order to calculate body mass index (BMI) (mass/stature2). Obesity, defined as a morphological risk, was classified according to the World Health Organisation (WHO) BMI criteria (BMI>30kg.m-2), as well as according to measures of waist circumference (WC) and body composition. Hypertension, hypercholesterolemia and type II diabetes, were grouped as cardiovascular (CV) risks. Hypertension was defined as a blood pressure greater than 140/90mmHg (JNC-7); hypercholesterolemia, as total cholesterol greater than 6.2mmol.L-1 (NCEP); and type II diabetes, as total glucose greater than 12mmol.L-1 (WHO). Physical activity, diet, tobacco use, and alcohol consumption and dependence were grouped as lifestyle-related risks. These were assessed by means of self-reporting through the use of various validated questionnaires. Finally, self-reporting of obesity, hypertension, hypercholesterolemia and type II diabetes was assessed, in addition to perception questions on individuals’ perceived body shape and size (Ziebland figures). Self-reported and perceived responses were then compared to actual measures. Females were significantly (p<0.001) heavier than the males (92.7kg compared to 72.1kg) and had significantly (p<0.001) higher BMIs than their male counterparts (37.6kg.m-2 compared to 25.7 kg.-2). They also recorded significantly (p<0.001) higher waist circumference (WC) values and had significantly (p<0.001) higher percentage and total body fat. Significantly (p<0.001) more females were obese (81%) compared to males (17%). While a higher percentage of males (25 % compared to 22%) presented with stage I hypertension (≥140/90mmHg, <160/95mmHg), significantly (p<0.05) more females (14% compared to 8%) presented with stage II hypertension (>160/95mmHg). The prevalence of hypercholesterolemia at a high level of risk (>6.2mmol.L-1) was relatively low (2.1 % of males, 3.4% of females), but notably more participants (22% of males and 26% of females) presented with the condition at a moderate level of risk (>5mmol.L-1). Type II diabetes was the least prevalent CV risk factor, with no males and only 3% of females presenting with the condition. Males consumed significantly (p<0.05) more in terms of total energy intake (9024 vs. 7234 kJ) and were significantly (p<0.05) more active (3315 compared to 2660 MET-mins.week). A significantly (p<0.05) higher percentage of males smoked (51.1% compared to 3.4%), consumed alcohol (73.4% compared to 46.6%) and were alcohol dependent (40% compared to 33.5%). Both males and females tended to be ignorant of their health status, with both samples under-reporting obesity, hypertension and hypercholesterolemia, while over-reporting type II diabetes. Furthermore, obesity was significantly (p<0.05) underestimated, with both male and female individuals perceiving themselves to be notably smaller than they actually were. Physical activity and diet were important determinants of CVD risk in this black urban sample of individuals. Obesity, in particular central adiposity, was the most notable risk (particularly in females), followed by hypertension (particularly in males). Although some risks presented at a moderate level of risk, a clustering of risk factors was evident in both samples, with 12.6% and 41.2% of males and females presenting with two risk factors, and 2.8% and 8.1% of males and females respectively presenting with three risks.
- Full Text:
- Date Issued: 2011
- Authors: Jackson, Lindsay May
- Date: 2011
- Subjects: Cardiovascular system -- Diseases -- South Africa -- Grahamstown , Obesity -- South Africa -- Grahamstown , Hypertension -- South Africa -- Grahamstown , Hypercholesteremia -- South Africa -- Grahamstown , Diabetes -- South Africa -- Grahamstown , Lifestyles -- Health aspects -- South Africa -- Grahamstown , Health behavior -- South Africa -- Grahamstown , Health attitudes -- South Africa -- Grahamstown , Black people -- South Africa -- Grahamstown -- Health and hygiene
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5127 , http://hdl.handle.net/10962/d1005205 , Cardiovascular system -- Diseases -- South Africa -- Grahamstown , Obesity -- South Africa -- Grahamstown , Hypertension -- South Africa -- Grahamstown , Hypercholesteremia -- South Africa -- Grahamstown , Diabetes -- South Africa -- Grahamstown , Lifestyles -- Health aspects -- South Africa -- Grahamstown , Health behavior -- South Africa -- Grahamstown , Health attitudes -- South Africa -- Grahamstown , Black people -- South Africa -- Grahamstown -- Health and hygiene
- Description: The aim of this research project was to assess and compare cardiovascular disease (CVD) risk in black males and females from an urban, working population in the Makana (Grahamstown) region of the Eastern Cape, South Africa. Two-hundred and ninety one individuals (males: n = 143, females: n = 148) with a mean age of 42.6 (±8.1) years were voluntarily recruited from the greater urban Makana (Grahamstown) area. Eight Cardiovascular disease (CVD) risks were assessed: stature and mass were obtained in order to calculate body mass index (BMI) (mass/stature2). Obesity, defined as a morphological risk, was classified according to the World Health Organisation (WHO) BMI criteria (BMI>30kg.m-2), as well as according to measures of waist circumference (WC) and body composition. Hypertension, hypercholesterolemia and type II diabetes, were grouped as cardiovascular (CV) risks. Hypertension was defined as a blood pressure greater than 140/90mmHg (JNC-7); hypercholesterolemia, as total cholesterol greater than 6.2mmol.L-1 (NCEP); and type II diabetes, as total glucose greater than 12mmol.L-1 (WHO). Physical activity, diet, tobacco use, and alcohol consumption and dependence were grouped as lifestyle-related risks. These were assessed by means of self-reporting through the use of various validated questionnaires. Finally, self-reporting of obesity, hypertension, hypercholesterolemia and type II diabetes was assessed, in addition to perception questions on individuals’ perceived body shape and size (Ziebland figures). Self-reported and perceived responses were then compared to actual measures. Females were significantly (p<0.001) heavier than the males (92.7kg compared to 72.1kg) and had significantly (p<0.001) higher BMIs than their male counterparts (37.6kg.m-2 compared to 25.7 kg.-2). They also recorded significantly (p<0.001) higher waist circumference (WC) values and had significantly (p<0.001) higher percentage and total body fat. Significantly (p<0.001) more females were obese (81%) compared to males (17%). While a higher percentage of males (25 % compared to 22%) presented with stage I hypertension (≥140/90mmHg, <160/95mmHg), significantly (p<0.05) more females (14% compared to 8%) presented with stage II hypertension (>160/95mmHg). The prevalence of hypercholesterolemia at a high level of risk (>6.2mmol.L-1) was relatively low (2.1 % of males, 3.4% of females), but notably more participants (22% of males and 26% of females) presented with the condition at a moderate level of risk (>5mmol.L-1). Type II diabetes was the least prevalent CV risk factor, with no males and only 3% of females presenting with the condition. Males consumed significantly (p<0.05) more in terms of total energy intake (9024 vs. 7234 kJ) and were significantly (p<0.05) more active (3315 compared to 2660 MET-mins.week). A significantly (p<0.05) higher percentage of males smoked (51.1% compared to 3.4%), consumed alcohol (73.4% compared to 46.6%) and were alcohol dependent (40% compared to 33.5%). Both males and females tended to be ignorant of their health status, with both samples under-reporting obesity, hypertension and hypercholesterolemia, while over-reporting type II diabetes. Furthermore, obesity was significantly (p<0.05) underestimated, with both male and female individuals perceiving themselves to be notably smaller than they actually were. Physical activity and diet were important determinants of CVD risk in this black urban sample of individuals. Obesity, in particular central adiposity, was the most notable risk (particularly in females), followed by hypertension (particularly in males). Although some risks presented at a moderate level of risk, a clustering of risk factors was evident in both samples, with 12.6% and 41.2% of males and females presenting with two risk factors, and 2.8% and 8.1% of males and females respectively presenting with three risks.
- Full Text:
- Date Issued: 2011
Management and performance indicators of micro-finance institutions in Uganda
- Authors: Milly, Kwagala
- Date: 2011
- Subjects: Microfinance -- Uganda , Financial institutions -- Uganda -- Management , Management , Performance standards
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9273 , http://hdl.handle.net/10948/1641 , Microfinance -- Uganda , Financial institutions -- Uganda -- Management , Management , Performance standards
- Description: The purpose of this study is to examine how the management of micro-finance institutions in Uganda has affected the performance indicators of these institutions, and whether or not the management of these institutions is responsible for their failure. The need to carry out this study arose as micro-finance institutions in Uganda failed to attain their planned performance indicators, to such a degree that most of them closed down. Although at their inception there was considerable entrepreneurial activity supported by a highly favourable government policy environment, their closure soon after establishment raised concern as to what caused them to fail. This study was encouraged by the observation that most of these institutions failed to realise their performance indicators as planned, but the underlying cause was not clear. Thus, the study focuses on establishing stakeholder perceptions of the management of the micro-finance institutions, and the relationship between their management (planning, implementation of planned programmes, and control) and their performance indicators, following the rationale of the functional and contingency paradigms of the concept of management. The study examines the way management dealt with these institutions‟ internal and external environments to influence their ability to realise their planned performance. The study is conducted using positivistic research methodology. This involved a collection of quantitative data from a sample of 454 respondents, including 64 managers, 177 employees, and 213 clients. Structured questionnaires were used to collect the data, and purposive and convenience sampling were applied to select the respondents. The respondents were selected from 56 randomly selected micro-finance institutions operating in Central Uganda and representing 75 percent of the country‟s operational institutions by December 2009. The data were analysed using the narrative, chi-square test, the ANOVA, factor analysis, and correlation and regression methods of analysis aided by the SPSS programme. The findings show that 79.2 percent of stakeholders (managers, employees, and clients) perceived that the management of their institutions was not conducted well in terms of planning, plan implementation, and control. Eighty-one (81) percent of both managers and employees and 83.4 percent of clients held the perception that the institutions failed xvi to achieve their performance indicators as planned. Furthermore, 81.7 percent of both managers and employees described their institutions‟ internal environment as largely defined by unsatisfactory supervision, and 66.9 percent of them revealed that their institutions‟ external environment was defined by family relations. These relations adversely affected the ownership, decision-making, employee recruitment, and deployment in the institutions. The findings also show that there were significant positive but weak relationships between management (planning, implementation, control, and dealing with the internal environment and the impact of the external environment) and the performance indicators of the institutions. The management of the institutions realised only 24.8 percent of their predicted performance indicators. Of the 13 null hypotheses that were formulated for this study, seven were rejected and the alternative hypotheses were accepted, while six were accepted. All the dimensions of the management of the micro-finance institutions in Uganda need to be developed if the performance of the institutions is to be improved and sustained to desired levels. It is suggested that large performance improvements will be realised by ameliorating all the dimensions of the institutions' management, while placing more emphasis on improving the following dimensions: the organisation of the institutions; the managing of their internal environment and the impact of their external environment; the conduct of their internal concurrent control; and the planning of their performance indicators and marketing, involving all the stakeholders, in particular the managers, employees, clients, Government, and the Uganda Micro-finance Forum, where necessary. Further research is recommended into other factors affecting the performance indicators of the institutions, since none of the management functions had explained them properly.
- Full Text:
- Date Issued: 2011
- Authors: Milly, Kwagala
- Date: 2011
- Subjects: Microfinance -- Uganda , Financial institutions -- Uganda -- Management , Management , Performance standards
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9273 , http://hdl.handle.net/10948/1641 , Microfinance -- Uganda , Financial institutions -- Uganda -- Management , Management , Performance standards
- Description: The purpose of this study is to examine how the management of micro-finance institutions in Uganda has affected the performance indicators of these institutions, and whether or not the management of these institutions is responsible for their failure. The need to carry out this study arose as micro-finance institutions in Uganda failed to attain their planned performance indicators, to such a degree that most of them closed down. Although at their inception there was considerable entrepreneurial activity supported by a highly favourable government policy environment, their closure soon after establishment raised concern as to what caused them to fail. This study was encouraged by the observation that most of these institutions failed to realise their performance indicators as planned, but the underlying cause was not clear. Thus, the study focuses on establishing stakeholder perceptions of the management of the micro-finance institutions, and the relationship between their management (planning, implementation of planned programmes, and control) and their performance indicators, following the rationale of the functional and contingency paradigms of the concept of management. The study examines the way management dealt with these institutions‟ internal and external environments to influence their ability to realise their planned performance. The study is conducted using positivistic research methodology. This involved a collection of quantitative data from a sample of 454 respondents, including 64 managers, 177 employees, and 213 clients. Structured questionnaires were used to collect the data, and purposive and convenience sampling were applied to select the respondents. The respondents were selected from 56 randomly selected micro-finance institutions operating in Central Uganda and representing 75 percent of the country‟s operational institutions by December 2009. The data were analysed using the narrative, chi-square test, the ANOVA, factor analysis, and correlation and regression methods of analysis aided by the SPSS programme. The findings show that 79.2 percent of stakeholders (managers, employees, and clients) perceived that the management of their institutions was not conducted well in terms of planning, plan implementation, and control. Eighty-one (81) percent of both managers and employees and 83.4 percent of clients held the perception that the institutions failed xvi to achieve their performance indicators as planned. Furthermore, 81.7 percent of both managers and employees described their institutions‟ internal environment as largely defined by unsatisfactory supervision, and 66.9 percent of them revealed that their institutions‟ external environment was defined by family relations. These relations adversely affected the ownership, decision-making, employee recruitment, and deployment in the institutions. The findings also show that there were significant positive but weak relationships between management (planning, implementation, control, and dealing with the internal environment and the impact of the external environment) and the performance indicators of the institutions. The management of the institutions realised only 24.8 percent of their predicted performance indicators. Of the 13 null hypotheses that were formulated for this study, seven were rejected and the alternative hypotheses were accepted, while six were accepted. All the dimensions of the management of the micro-finance institutions in Uganda need to be developed if the performance of the institutions is to be improved and sustained to desired levels. It is suggested that large performance improvements will be realised by ameliorating all the dimensions of the institutions' management, while placing more emphasis on improving the following dimensions: the organisation of the institutions; the managing of their internal environment and the impact of their external environment; the conduct of their internal concurrent control; and the planning of their performance indicators and marketing, involving all the stakeholders, in particular the managers, employees, clients, Government, and the Uganda Micro-finance Forum, where necessary. Further research is recommended into other factors affecting the performance indicators of the institutions, since none of the management functions had explained them properly.
- Full Text:
- Date Issued: 2011
Management and the dynamics of labour process: study of workplace relations in an oil refinery, Nigeria
- Oladeinde, Olusegun Olurotimi
- Authors: Oladeinde, Olusegun Olurotimi
- Date: 2011
- Subjects: Nigerian National Petroleum Corporation Personnel management -- Nigeria Petroleum industry and trade -- Personnel management -- Nigeria Performance -- Management -- Nigeria Industrial relations -- Nigeria Organizational behavior -- Nigeria Total quality management -- Nigeria Labor unions -- Nigeria Petroleum workers -- Nigeria -- Attitudes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3299 , http://hdl.handle.net/10962/d1003087
- Description: The focus of this thesis is on labour-management relations in the Nigerian National Petroleum Corporation (NNPC), Nigeria. The study explores current managerial practices in the corporation and their effects on the intensification of work, and how the management sought to control workers and the labour process. The study explores the experiences of workers and their perception of managerial practices. Evidence suggests that managerial practices and their impacts on workplace relations in NNPC have become more subtle, with wider implications for workers’ experience and the labour process. Using primary data obtained through interviews, participant observation, and documentary sources, the thesis assesses how managerial practices are varieties of controls of labour in which workers’ consent is also embedded. This embeddedness of the labour process generates new types of worker subjectivity and identity, with significant implications for labour relations. The study suggests that multiple dimensions of workers’ sense-making reflect the structural and subjective dimensions of the labour process. In NNPC, the consequence of managerial practices has been an emergence of a new type of subjectivity; one that has closely identified with the corporate values and is not overtly disposed towards resistance or dissent. While workers consent at NNPC continues to be an outcome of managerial practices, the thesis examined its implications. The thesis seeks to explain the effects of managerial control mechanisms in shaping workers’ experience and identity. However, the thesis shows that while workers remain susceptible to these forms of managerial influence, an erasure or closure of oppositions or recalcitrance will not adequately account for workers’ identity-formation. The thesis shows that while managerial control remains significant, workers inhabit domains that are ‘unmanaged’ and ‘unmanageable’ where ‘resistance’ and ‘misbehaviour’ reside. Without a conceptual and empirical interrogation, evidence of normative and mutual benefits of managerial practices or a submissive image of workers will produce images of workers that obscure their covert opposition and resistance. Workers ‘collude’ with the ‘hubris’ of management in order to invert and subvert managerial practices and intentions. Through theoretical reconceptualization, the thesis demonstrates the specific dimensions of these inversions and subversions. The thesis therefore seeks to re-insert “worker-agency” back into the analysis of power-relations in the workplace; agency that is not overtly under the absolute grip of managerial control, but with a multiplicity of identities and multilevel manifestations.
- Full Text:
- Date Issued: 2011
- Authors: Oladeinde, Olusegun Olurotimi
- Date: 2011
- Subjects: Nigerian National Petroleum Corporation Personnel management -- Nigeria Petroleum industry and trade -- Personnel management -- Nigeria Performance -- Management -- Nigeria Industrial relations -- Nigeria Organizational behavior -- Nigeria Total quality management -- Nigeria Labor unions -- Nigeria Petroleum workers -- Nigeria -- Attitudes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3299 , http://hdl.handle.net/10962/d1003087
- Description: The focus of this thesis is on labour-management relations in the Nigerian National Petroleum Corporation (NNPC), Nigeria. The study explores current managerial practices in the corporation and their effects on the intensification of work, and how the management sought to control workers and the labour process. The study explores the experiences of workers and their perception of managerial practices. Evidence suggests that managerial practices and their impacts on workplace relations in NNPC have become more subtle, with wider implications for workers’ experience and the labour process. Using primary data obtained through interviews, participant observation, and documentary sources, the thesis assesses how managerial practices are varieties of controls of labour in which workers’ consent is also embedded. This embeddedness of the labour process generates new types of worker subjectivity and identity, with significant implications for labour relations. The study suggests that multiple dimensions of workers’ sense-making reflect the structural and subjective dimensions of the labour process. In NNPC, the consequence of managerial practices has been an emergence of a new type of subjectivity; one that has closely identified with the corporate values and is not overtly disposed towards resistance or dissent. While workers consent at NNPC continues to be an outcome of managerial practices, the thesis examined its implications. The thesis seeks to explain the effects of managerial control mechanisms in shaping workers’ experience and identity. However, the thesis shows that while workers remain susceptible to these forms of managerial influence, an erasure or closure of oppositions or recalcitrance will not adequately account for workers’ identity-formation. The thesis shows that while managerial control remains significant, workers inhabit domains that are ‘unmanaged’ and ‘unmanageable’ where ‘resistance’ and ‘misbehaviour’ reside. Without a conceptual and empirical interrogation, evidence of normative and mutual benefits of managerial practices or a submissive image of workers will produce images of workers that obscure their covert opposition and resistance. Workers ‘collude’ with the ‘hubris’ of management in order to invert and subvert managerial practices and intentions. Through theoretical reconceptualization, the thesis demonstrates the specific dimensions of these inversions and subversions. The thesis therefore seeks to re-insert “worker-agency” back into the analysis of power-relations in the workplace; agency that is not overtly under the absolute grip of managerial control, but with a multiplicity of identities and multilevel manifestations.
- Full Text:
- Date Issued: 2011
Management of type 2 diabetes mellitus : a pharmacoepidemiological review
- Authors: Saugur, Anusooya
- Date: 2011
- Subjects: Diabetes , Diabetes -- Management , Diabetes -- Diet therapy , Diabetes -- Prevention , Insulin -- Therapeutic use , Hypoglycemia
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: vital:10129 , http://hdl.handle.net/10948/1635 , Diabetes , Diabetes -- Management , Diabetes -- Diet therapy , Diabetes -- Prevention , Insulin -- Therapeutic use , Hypoglycemia
- Description: Type 2 diabetes mellitus (DM) is a progressive disease characterised by hyperglycaemia caused by defects in insulin secretion and insulin action. In early stages of type 2 DM, dietary and lifestyle changes are often sufficient to control blood glucose levels. However, over time, many patients experience β cell dysfunction and require insulin therapy, either alone or in combination with oral agents. There are guidelines available to structure the management of this disease state, including both the use of oral hypoglycaemic agents and or insulin. Besides health complications, there are economic burdens associated with the management of type 2 diabetes mellitus. The aim of this study was to determine the management of type 2 DM in a South African sample group of patients drawn from a large medical aid database. The objectives of the study were: to establish the prevalence of type 2 DM relative to age, examine the nature of chronic comorbid disease states, establish trends in the prescribing of insulin relative to other oral hypoglycaemic agents, investigate cost implications, and determine trends in the use of blood and urine monitoring materials by patients. The study was quantitative and retrospective and descriptive statistics were used in the analysis. DM was found to be most prevalent amongst patients between 50 and 59 years old. Results also demonstrated that 83% of DM patients also suffered from other chronic comorbid diseases, with cardiovascular diseases, especially hypertension and hypercholesterolaemia being the most prominent. This study also revealed that DM is predominantly managed with oral hypoglycaemic agents. Changes in drug prescribing, for chronic disease states such as DM may have medical, social and economic implications both for individual patients and for society and it is envisaged that the results of this study can be used to influence future management of DM. Keywords: Pharmacoepidemiology, management, type 2 diabetes mellitus
- Full Text:
- Date Issued: 2011
- Authors: Saugur, Anusooya
- Date: 2011
- Subjects: Diabetes , Diabetes -- Management , Diabetes -- Diet therapy , Diabetes -- Prevention , Insulin -- Therapeutic use , Hypoglycemia
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: vital:10129 , http://hdl.handle.net/10948/1635 , Diabetes , Diabetes -- Management , Diabetes -- Diet therapy , Diabetes -- Prevention , Insulin -- Therapeutic use , Hypoglycemia
- Description: Type 2 diabetes mellitus (DM) is a progressive disease characterised by hyperglycaemia caused by defects in insulin secretion and insulin action. In early stages of type 2 DM, dietary and lifestyle changes are often sufficient to control blood glucose levels. However, over time, many patients experience β cell dysfunction and require insulin therapy, either alone or in combination with oral agents. There are guidelines available to structure the management of this disease state, including both the use of oral hypoglycaemic agents and or insulin. Besides health complications, there are economic burdens associated with the management of type 2 diabetes mellitus. The aim of this study was to determine the management of type 2 DM in a South African sample group of patients drawn from a large medical aid database. The objectives of the study were: to establish the prevalence of type 2 DM relative to age, examine the nature of chronic comorbid disease states, establish trends in the prescribing of insulin relative to other oral hypoglycaemic agents, investigate cost implications, and determine trends in the use of blood and urine monitoring materials by patients. The study was quantitative and retrospective and descriptive statistics were used in the analysis. DM was found to be most prevalent amongst patients between 50 and 59 years old. Results also demonstrated that 83% of DM patients also suffered from other chronic comorbid diseases, with cardiovascular diseases, especially hypertension and hypercholesterolaemia being the most prominent. This study also revealed that DM is predominantly managed with oral hypoglycaemic agents. Changes in drug prescribing, for chronic disease states such as DM may have medical, social and economic implications both for individual patients and for society and it is envisaged that the results of this study can be used to influence future management of DM. Keywords: Pharmacoepidemiology, management, type 2 diabetes mellitus
- Full Text:
- Date Issued: 2011
Marine anti-malarial isonitriles : a synthetic and computational study
- Authors: Adendorff, Matthew Ralph
- Date: 2011 , 2010-05-17
- Subjects: Isocyanides , Isocyanates , Marine pharmacology , Antimalarials , Antimalarials -- Development , Drug development
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4398 , http://hdl.handle.net/10962/d1006674 , Isocyanides , Isocyanates , Marine pharmacology , Antimalarials , Antimalarials -- Development , Drug development
- Description: The development of Plasmodium falciparum malarial resistance to the current armoury of anti-malarial drugs requires the development of new treatments to help combat this disease. The marine environment is a well established source of potential pharmaceuticals. Of interest to us are isonitrile, isocyanate and isothiocyanate compounds isolated from marine sponges and molluscs which have exhibited nano-molar anti-plasmodial activities. Through quantitative structure-activity relation studies (QSAR), a literature precedent exists for a pseudoreceptor model from which a pharmacophore for the design of novel anti-malarial agents was proposed. The current theory suggests that these marine compounds exert their inhibitory action through interfering with the heme detoxification pathway in P. falciparum. We propose that the computational methods used to draw detailed conclusions about the mode of action of these marine compounds were inadequate. This thesis addresses this problem using contemporary computational methodologies and seeks to propose a more robust method for the rational design of new anti-malarial drug compounds that inhibit heme polymerization to hemozoin. In order to investigate the interactions of the marine compounds with their heme targets, a series of modern computational procedures were formulated, validated and then applied to theoretical systems. The validations of these algorithms, before their application to the marine compound-heme systems, were achieved through two case studies. The first was used to investigate the applicability of the statistical docking algorithm AutoDock to be used for the exploration of conformational space around the heme target. A theoretical P. falciparum 1-deoxy-D-xylulose-5-phosphate reductoisomerase (PfDXR) enzyme model, constructed by the Biochemistry Department at Rhodes University, provided the ideal model to validate the AutoDock program. The protein model was accordingly subjected to rigorous docking simulations with over 30 different ligand molecules using the AutoDock algorithm which allowed for the docking algorithm’s limitations to be ascertained and improved upon. This investigation facilitated the successful validation of the protein model, which can now be used for the rational design of new PfDXR-inhibiting anti-plasmodial compounds, as well as enabling us to propose an improvement of the docking algorithm for application to the heme systems. The second case study was used to investigate the applicability of an ab initio molecular dynamics algorithm for simulation of bond breaking/forming events between the marine compounds and their heme target. This validation involved the exploration of intermolecular interactions in a naturally occurring nonoligomeric zipper using the Car-Parrinello Molecular Dynamics (CPMD) method. This study allowed us to propose a model for the intermolecular forces responsible for zipper self-assembly and showcased the CPMD method’s abilities to simulate and predict bond forming/breaking events. Data from the computational analyses suggested that the interactions between marine isonitriles, isocyanates and isothiocyanates occur through bond-less electrostatic attractions rather than through formal intermolecular bonds as had been previously suggested. Accordingly, a simple bicyclic tertiary isonitrile (5.14) was synthesized using Kitano et al’s relatively underutilized isonitrile synthetic method for the conversion of tertiary alcohols to their corresponding isonitriles. This compound’s potential for heme detoxification inhibition was then explored in vitro via the pyridine-hemochrome assay. The assay data suggested that the synthesized isonitrile was capable of inhibiting heme polymerization in a similar fashion to the known inhibitor chloroquine. Attempts to synthesize tricyclic analogues of 5.14 were unsuccessful and highlighted the limitation of Kitano et al’s isonitrile synthetic methodology.
- Full Text:
- Date Issued: 2011
- Authors: Adendorff, Matthew Ralph
- Date: 2011 , 2010-05-17
- Subjects: Isocyanides , Isocyanates , Marine pharmacology , Antimalarials , Antimalarials -- Development , Drug development
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4398 , http://hdl.handle.net/10962/d1006674 , Isocyanides , Isocyanates , Marine pharmacology , Antimalarials , Antimalarials -- Development , Drug development
- Description: The development of Plasmodium falciparum malarial resistance to the current armoury of anti-malarial drugs requires the development of new treatments to help combat this disease. The marine environment is a well established source of potential pharmaceuticals. Of interest to us are isonitrile, isocyanate and isothiocyanate compounds isolated from marine sponges and molluscs which have exhibited nano-molar anti-plasmodial activities. Through quantitative structure-activity relation studies (QSAR), a literature precedent exists for a pseudoreceptor model from which a pharmacophore for the design of novel anti-malarial agents was proposed. The current theory suggests that these marine compounds exert their inhibitory action through interfering with the heme detoxification pathway in P. falciparum. We propose that the computational methods used to draw detailed conclusions about the mode of action of these marine compounds were inadequate. This thesis addresses this problem using contemporary computational methodologies and seeks to propose a more robust method for the rational design of new anti-malarial drug compounds that inhibit heme polymerization to hemozoin. In order to investigate the interactions of the marine compounds with their heme targets, a series of modern computational procedures were formulated, validated and then applied to theoretical systems. The validations of these algorithms, before their application to the marine compound-heme systems, were achieved through two case studies. The first was used to investigate the applicability of the statistical docking algorithm AutoDock to be used for the exploration of conformational space around the heme target. A theoretical P. falciparum 1-deoxy-D-xylulose-5-phosphate reductoisomerase (PfDXR) enzyme model, constructed by the Biochemistry Department at Rhodes University, provided the ideal model to validate the AutoDock program. The protein model was accordingly subjected to rigorous docking simulations with over 30 different ligand molecules using the AutoDock algorithm which allowed for the docking algorithm’s limitations to be ascertained and improved upon. This investigation facilitated the successful validation of the protein model, which can now be used for the rational design of new PfDXR-inhibiting anti-plasmodial compounds, as well as enabling us to propose an improvement of the docking algorithm for application to the heme systems. The second case study was used to investigate the applicability of an ab initio molecular dynamics algorithm for simulation of bond breaking/forming events between the marine compounds and their heme target. This validation involved the exploration of intermolecular interactions in a naturally occurring nonoligomeric zipper using the Car-Parrinello Molecular Dynamics (CPMD) method. This study allowed us to propose a model for the intermolecular forces responsible for zipper self-assembly and showcased the CPMD method’s abilities to simulate and predict bond forming/breaking events. Data from the computational analyses suggested that the interactions between marine isonitriles, isocyanates and isothiocyanates occur through bond-less electrostatic attractions rather than through formal intermolecular bonds as had been previously suggested. Accordingly, a simple bicyclic tertiary isonitrile (5.14) was synthesized using Kitano et al’s relatively underutilized isonitrile synthetic method for the conversion of tertiary alcohols to their corresponding isonitriles. This compound’s potential for heme detoxification inhibition was then explored in vitro via the pyridine-hemochrome assay. The assay data suggested that the synthesized isonitrile was capable of inhibiting heme polymerization in a similar fashion to the known inhibitor chloroquine. Attempts to synthesize tricyclic analogues of 5.14 were unsuccessful and highlighted the limitation of Kitano et al’s isonitrile synthetic methodology.
- Full Text:
- Date Issued: 2011
Measurement of the bulk flow and transport characteristics of selected fractured rock aquifer systems in South Africa: a case study of the Balfour Formation in the Eastern Cape Province
- Authors: Yu, Liuji
- Date: 2011
- Subjects: Aquifers -- South Africa -- Eastern Cape , Groundwater -- South Africa -- Eastern Cape , Water well drilling -- South Africa -- Eastern Cape , Sedimentary structures -- South Africa -- Eastern Cape , Formations (Geology) -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc (Geology)
- Identifier: vital:11522 , http://hdl.handle.net/10353/415 , Aquifers -- South Africa -- Eastern Cape , Groundwater -- South Africa -- Eastern Cape , Water well drilling -- South Africa -- Eastern Cape , Sedimentary structures -- South Africa -- Eastern Cape , Formations (Geology) -- South Africa -- Eastern Cape
- Description: Hydrogeologists have faced serious challenges worldwide in the characterization of fractured rock aquifers due to the heterogeneous nature of the imbedded geology. The bulk flow parameters in the Karoo strata in South Africa are specifically uncertain since most models are based on homogenous block systems. As part of a WRC research project, entitled “Measurement of the bulk flow and transport characteristics of selected fractured rock aquifer systems in South Africa”, this study focuses on the characterization, borehole drilling, flow parameter measurements and groundwater quality assessment of the Balfour Formation in the Beaufort Group of the Karoo Supergroup in the Eastern Cape, South Africa, which is seriously heterogeneous in deposition and has also been largely neglected as drilling targets for groundwater. The Balfour Formation comprises mostly mudstone, shale and sandstone, formed in a braided and meandering river system. In addition to the heterogeneous deposition, the flow pathways in this aquifer system are not fully understood due to lack of actual measurement data. The methods used in this study include field mapping, site characterization, borehole drilling, and pumping and tracer testing in order to obtain the borehole yield, aquifer transmissivity, storativity and groundwater flow velocity. In addition, the groundwater chemistry was also studied to determine quality for use and possible connectivity with the nearby Tyume River and to determine potential sources of groundwater contamination. The results obtained include: 1) The study area is predominantly mudstone/shale with thin layers and lenses of siltstone and sandstone, which are interbedded; 2) Two boreholes were successfully drilled, which had yields in excess of 10 l/s in four water levels (at 7, 22, 54 and 65 m); 3) The estimated average transmissivity is 246 m 2/day according to the recovery test; 4) The estimated seepage velocity is 120 m/day according to tracer tests in the aquifer between the two boreholes which are 5 m apart; and 5) The water chemical type is the combination of HCO3-, Cl-and SO42- , which is distinguishable from that of the Tyume river; 6) There is no evidence for groundwater recharge to the deep aquifers from the Tyume river, based on the differences of the water chemistry; 7) The elements Ca, Cl, Na and C are distributed more than 90% as free ion species in BH2 borehole water; and 8) The groundwater in BH2 borehole is undersaturated (negative SI) with respect to some minerals (for example: anhydrite, fluorite, gypsum and halite), oversaturated (positive SI) with respect to some minerals (for example: aragonite, calcite and dolomite). It is concluded that there is a great potential to obtain drilling targets for high yielding boreholes in the sedimentary rocks of the Balfour Formation in the Karoo Supergroup.
- Full Text:
- Date Issued: 2011
- Authors: Yu, Liuji
- Date: 2011
- Subjects: Aquifers -- South Africa -- Eastern Cape , Groundwater -- South Africa -- Eastern Cape , Water well drilling -- South Africa -- Eastern Cape , Sedimentary structures -- South Africa -- Eastern Cape , Formations (Geology) -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc (Geology)
- Identifier: vital:11522 , http://hdl.handle.net/10353/415 , Aquifers -- South Africa -- Eastern Cape , Groundwater -- South Africa -- Eastern Cape , Water well drilling -- South Africa -- Eastern Cape , Sedimentary structures -- South Africa -- Eastern Cape , Formations (Geology) -- South Africa -- Eastern Cape
- Description: Hydrogeologists have faced serious challenges worldwide in the characterization of fractured rock aquifers due to the heterogeneous nature of the imbedded geology. The bulk flow parameters in the Karoo strata in South Africa are specifically uncertain since most models are based on homogenous block systems. As part of a WRC research project, entitled “Measurement of the bulk flow and transport characteristics of selected fractured rock aquifer systems in South Africa”, this study focuses on the characterization, borehole drilling, flow parameter measurements and groundwater quality assessment of the Balfour Formation in the Beaufort Group of the Karoo Supergroup in the Eastern Cape, South Africa, which is seriously heterogeneous in deposition and has also been largely neglected as drilling targets for groundwater. The Balfour Formation comprises mostly mudstone, shale and sandstone, formed in a braided and meandering river system. In addition to the heterogeneous deposition, the flow pathways in this aquifer system are not fully understood due to lack of actual measurement data. The methods used in this study include field mapping, site characterization, borehole drilling, and pumping and tracer testing in order to obtain the borehole yield, aquifer transmissivity, storativity and groundwater flow velocity. In addition, the groundwater chemistry was also studied to determine quality for use and possible connectivity with the nearby Tyume River and to determine potential sources of groundwater contamination. The results obtained include: 1) The study area is predominantly mudstone/shale with thin layers and lenses of siltstone and sandstone, which are interbedded; 2) Two boreholes were successfully drilled, which had yields in excess of 10 l/s in four water levels (at 7, 22, 54 and 65 m); 3) The estimated average transmissivity is 246 m 2/day according to the recovery test; 4) The estimated seepage velocity is 120 m/day according to tracer tests in the aquifer between the two boreholes which are 5 m apart; and 5) The water chemical type is the combination of HCO3-, Cl-and SO42- , which is distinguishable from that of the Tyume river; 6) There is no evidence for groundwater recharge to the deep aquifers from the Tyume river, based on the differences of the water chemistry; 7) The elements Ca, Cl, Na and C are distributed more than 90% as free ion species in BH2 borehole water; and 8) The groundwater in BH2 borehole is undersaturated (negative SI) with respect to some minerals (for example: anhydrite, fluorite, gypsum and halite), oversaturated (positive SI) with respect to some minerals (for example: aragonite, calcite and dolomite). It is concluded that there is a great potential to obtain drilling targets for high yielding boreholes in the sedimentary rocks of the Balfour Formation in the Karoo Supergroup.
- Full Text:
- Date Issued: 2011
Membership attraction and retention strategies for the Port Elizabeth Club
- Authors: Geel, Rudolf Christiaan
- Date: 2011
- Subjects: Organizational change -- South Africa -- Port Elizabeth -- Management , Organizational change -- Social aspects -- South Africa -- Port Elizabeth , Strategic planning -- South Africa -- Port Elizabeth , Clubs -- South Africa -- Port Elizabeth , Success in business -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8587 , http://hdl.handle.net/10948/1643 , Organizational change -- South Africa -- Port Elizabeth -- Management , Organizational change -- Social aspects -- South Africa -- Port Elizabeth , Strategic planning -- South Africa -- Port Elizabeth , Clubs -- South Africa -- Port Elizabeth , Success in business -- South Africa -- Port Elizabeth
- Description: Human beings have been gathering with other human beings for any and all reasons. These gatherings have occurred since biblical times. The Roman baths were the first gatherings that can be classified as clubs. In contemporary terms, humans gather in small numbers for a coffee with friends at a coffee restaurant, they gather in the thousands to show their dejection of wage offerings and they gather in the millions to support a sports jersey. The common factor in all of these gatherings is that they do it because of one shared goal, one shared vision. The places where people with the same interests gather, called clubs and organisations, have been around for many years. They fulfil some of the very basic human needs as well as some of the most intricate human wants. Ensuring that clubs or organisations remain in our social fibre for many years to come is in the best interest of all of their stakeholders. These clubs or organisations need to adjust to the times of present and adjust the offering they make to the members as the needs of the members change over time. It is this premise that led the researcher to The Port Elizabeth Club. This social club is struggling with dwindling membership numbers and the development of a membership strategy that will increase its membership numbers and the benefits that are offered to them. The secondary literature study conducted revealed many benefits and strategies that clubs currently use or that they could use to improve their membership brand. It further showed the different approaches, of the different clubs, to attracting and retaining the members they wanted. These benefits and strategies formed the basis iv of the primary study that was conducted by the researcher and were the main constructs in the study. The primary study was in the form of questionnaires and these were given to the target market of The Port Elizabeth Club as well as The Port Elizabeth Club members themselves. The primary study revealed that many of the benefits and strategies found in the literature can be used by The Port Elizabeth Club to improve their membership offering. The literature also stated this type of study, a questionnaire or survey, should be done on a regular basis by The Port Elizabeth Club to ensure that it is on track with its members’ needs and wants. The literature revealed that many club members feel that the value that is offered by clubs are diminishing and this results in the loss of members and disinterest from prospective members. It is for this reason that the research study conducted is important to The Port Elizabeth Club and shows that they should focus on the value they offer to their members and continue to improve this value offering. The research study concludes with a detailed description of benefits that The Port Elizabeth Club could implement for its members as well as strategies that will assist it in attracting new members and retaining its current members.
- Full Text:
- Date Issued: 2011
- Authors: Geel, Rudolf Christiaan
- Date: 2011
- Subjects: Organizational change -- South Africa -- Port Elizabeth -- Management , Organizational change -- Social aspects -- South Africa -- Port Elizabeth , Strategic planning -- South Africa -- Port Elizabeth , Clubs -- South Africa -- Port Elizabeth , Success in business -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8587 , http://hdl.handle.net/10948/1643 , Organizational change -- South Africa -- Port Elizabeth -- Management , Organizational change -- Social aspects -- South Africa -- Port Elizabeth , Strategic planning -- South Africa -- Port Elizabeth , Clubs -- South Africa -- Port Elizabeth , Success in business -- South Africa -- Port Elizabeth
- Description: Human beings have been gathering with other human beings for any and all reasons. These gatherings have occurred since biblical times. The Roman baths were the first gatherings that can be classified as clubs. In contemporary terms, humans gather in small numbers for a coffee with friends at a coffee restaurant, they gather in the thousands to show their dejection of wage offerings and they gather in the millions to support a sports jersey. The common factor in all of these gatherings is that they do it because of one shared goal, one shared vision. The places where people with the same interests gather, called clubs and organisations, have been around for many years. They fulfil some of the very basic human needs as well as some of the most intricate human wants. Ensuring that clubs or organisations remain in our social fibre for many years to come is in the best interest of all of their stakeholders. These clubs or organisations need to adjust to the times of present and adjust the offering they make to the members as the needs of the members change over time. It is this premise that led the researcher to The Port Elizabeth Club. This social club is struggling with dwindling membership numbers and the development of a membership strategy that will increase its membership numbers and the benefits that are offered to them. The secondary literature study conducted revealed many benefits and strategies that clubs currently use or that they could use to improve their membership brand. It further showed the different approaches, of the different clubs, to attracting and retaining the members they wanted. These benefits and strategies formed the basis iv of the primary study that was conducted by the researcher and were the main constructs in the study. The primary study was in the form of questionnaires and these were given to the target market of The Port Elizabeth Club as well as The Port Elizabeth Club members themselves. The primary study revealed that many of the benefits and strategies found in the literature can be used by The Port Elizabeth Club to improve their membership offering. The literature also stated this type of study, a questionnaire or survey, should be done on a regular basis by The Port Elizabeth Club to ensure that it is on track with its members’ needs and wants. The literature revealed that many club members feel that the value that is offered by clubs are diminishing and this results in the loss of members and disinterest from prospective members. It is for this reason that the research study conducted is important to The Port Elizabeth Club and shows that they should focus on the value they offer to their members and continue to improve this value offering. The research study concludes with a detailed description of benefits that The Port Elizabeth Club could implement for its members as well as strategies that will assist it in attracting new members and retaining its current members.
- Full Text:
- Date Issued: 2011
Microelectrochemical patterning of gold surfaces using 4-azidobenzenediazonium and scanning electrochemical microscopy
- Coates, Megan, Cabet, Eva, Griveau, Sophie, Nyokong, Tebello, Bedioui, Fethi
- Authors: Coates, Megan , Cabet, Eva , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247926 , vital:51630 , xlink:href="https://doi.org/10.1016/j.elecom.2010.11.037"
- Description: This work describes for the first time the possibility of performing local micro electrochemical grafting of a gold substrate by 4-azidobenzenediazonium by SECM in a single and simple one step without complications from adsorption. The electrografted spots of diazonium were performed by positioning a Pt tip at a given distance above the gold substrate and the SECM was used in a three-electrode configuration (the Pt tip serving as the microanode) in acetonitrile containing 5 mM 4-azidobenzenediazonium and 0.1 M Bu4NBF4 during 10 ms. The dimensions of the derivatized areas of the substrates were finely tuned by using different experimental conditions (tip distance above the substrate, tip diameter, presence or absence of supporting electrolyte). The use of the azido-derivated diazonium molecule and these preliminary results open the gate to important applications and developments devoted to the local micro functionalization of electrodes by thin layers that allow the implementation of the emerging and attractive interfacial click reaction.
- Full Text:
- Date Issued: 2011
- Authors: Coates, Megan , Cabet, Eva , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247926 , vital:51630 , xlink:href="https://doi.org/10.1016/j.elecom.2010.11.037"
- Description: This work describes for the first time the possibility of performing local micro electrochemical grafting of a gold substrate by 4-azidobenzenediazonium by SECM in a single and simple one step without complications from adsorption. The electrografted spots of diazonium were performed by positioning a Pt tip at a given distance above the gold substrate and the SECM was used in a three-electrode configuration (the Pt tip serving as the microanode) in acetonitrile containing 5 mM 4-azidobenzenediazonium and 0.1 M Bu4NBF4 during 10 ms. The dimensions of the derivatized areas of the substrates were finely tuned by using different experimental conditions (tip distance above the substrate, tip diameter, presence or absence of supporting electrolyte). The use of the azido-derivated diazonium molecule and these preliminary results open the gate to important applications and developments devoted to the local micro functionalization of electrodes by thin layers that allow the implementation of the emerging and attractive interfacial click reaction.
- Full Text:
- Date Issued: 2011
Microwave Mediated synthesis of cyclic compounds
- Authors: Ndebvu, Rumbidzayi
- Date: 2011
- Subjects: Cyclic compounds -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:18488 , http://hdl.handle.net/11260/d1007382
- Description: The scope of microwave induced synthesis of various cyclic compounds was investigated and considerably expanded. The advantages of this synthetic method were clearly demonstrated when compared to conventional heating methods of organic synthesis. The exposure of organic compounds to continual Ultraviolet (UV) radiation damages the materials and reduces their chemical and physical properties and in most cases irreversibly and this is not only a concern for industry but for consumers as well. Particularly prevalent are incidences of skin cancer now linked to UV radiation. Research efforts are directed towards finding cheap and efficient UV-absorbers to protect such light sensitive materials. Phenyl salicylates and hydroxybenzophenones constitute families of UV-absorber compounds, and this has necessitated this research. The condensation of differently substituted phenols with salicylic acid, catalyzed by either phosphoric acid (PPA), POCl3/ZnCl2 or ZnCl2 afforded the anticipated phenolic type UV -absorber molecules such as phenyl salicylate, 4-hydroxyphenyl-2-hydroxybenzoate, 2,3-dihydroxyphenyl-2-hydroxyphenylbenzoate, 3-hydroxyphenyl-2-hydroxybenzoate, (2,4-dihydroxyphenyl)(2-hydroxyphenyl)methanone, (2,3-dihydroxyphenyl)(2-hydroxyphenyl) methanone and 1,3-dihydroxyxanthone. PPA proved to be a more efficient catalyst for the condensation of salicylic acid with phenol, hydroquinone, pyrogallol and catechol while POCl3/ZnCl2 gave higher yields for resorcinol and phloroglucinol. In all cases, ZnCl2 alone did not show significant yield enhancement. The second part of this research work describes a convenient one-pot synthesis of NMethyl-2-pyrrolidone (NMP) an important industrial solvent by a conventional heating process and by microwave irradiation. The intermediate N-Methyl-hydroxybutyramide formed from the exothermic reaction of =-butyrolactone with aqueous monomethylamine, underwent an intramolecular condensation reaction catalyzed by highly active copper powder to form the anticipated product in very good yields.
- Full Text:
- Date Issued: 2011
- Authors: Ndebvu, Rumbidzayi
- Date: 2011
- Subjects: Cyclic compounds -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:18488 , http://hdl.handle.net/11260/d1007382
- Description: The scope of microwave induced synthesis of various cyclic compounds was investigated and considerably expanded. The advantages of this synthetic method were clearly demonstrated when compared to conventional heating methods of organic synthesis. The exposure of organic compounds to continual Ultraviolet (UV) radiation damages the materials and reduces their chemical and physical properties and in most cases irreversibly and this is not only a concern for industry but for consumers as well. Particularly prevalent are incidences of skin cancer now linked to UV radiation. Research efforts are directed towards finding cheap and efficient UV-absorbers to protect such light sensitive materials. Phenyl salicylates and hydroxybenzophenones constitute families of UV-absorber compounds, and this has necessitated this research. The condensation of differently substituted phenols with salicylic acid, catalyzed by either phosphoric acid (PPA), POCl3/ZnCl2 or ZnCl2 afforded the anticipated phenolic type UV -absorber molecules such as phenyl salicylate, 4-hydroxyphenyl-2-hydroxybenzoate, 2,3-dihydroxyphenyl-2-hydroxyphenylbenzoate, 3-hydroxyphenyl-2-hydroxybenzoate, (2,4-dihydroxyphenyl)(2-hydroxyphenyl)methanone, (2,3-dihydroxyphenyl)(2-hydroxyphenyl) methanone and 1,3-dihydroxyxanthone. PPA proved to be a more efficient catalyst for the condensation of salicylic acid with phenol, hydroquinone, pyrogallol and catechol while POCl3/ZnCl2 gave higher yields for resorcinol and phloroglucinol. In all cases, ZnCl2 alone did not show significant yield enhancement. The second part of this research work describes a convenient one-pot synthesis of NMethyl-2-pyrrolidone (NMP) an important industrial solvent by a conventional heating process and by microwave irradiation. The intermediate N-Methyl-hydroxybutyramide formed from the exothermic reaction of =-butyrolactone with aqueous monomethylamine, underwent an intramolecular condensation reaction catalyzed by highly active copper powder to form the anticipated product in very good yields.
- Full Text:
- Date Issued: 2011
MMORPG: Towards a Sustainable Livelihood Model for Africa and Beyond
- Mostert, André M, Kaschula, Russell H
- Authors: Mostert, André M , Kaschula, Russell H
- Date: 2011
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/175212 , vital:42553 , ISBN ViNOrg 2011 , https://link.springer.com/chapter/10.1007/978-3-642-31800-9_4
- Description: The burgeoning worlds of massively multiplayer online role-playing games (MMORPG) coupled with increasing access to the internet is opening a new paradigmatic window for a number of disciplines. Many of these have been slow to take up the challenges associated with this emergent framework, due, in no small measure, to the perception that work and play are mutually exclusive. The dominance of this dichotomy contributed to the slow uptake of the potential for these virtual worlds to be harnessed in the fields of education and employment. This reticence was due in no small measure to the technophobia that tends to characterise the adoption of new technologies within fields that have customarily eschewed an embrace.
- Full Text:
- Date Issued: 2011
- Authors: Mostert, André M , Kaschula, Russell H
- Date: 2011
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/175212 , vital:42553 , ISBN ViNOrg 2011 , https://link.springer.com/chapter/10.1007/978-3-642-31800-9_4
- Description: The burgeoning worlds of massively multiplayer online role-playing games (MMORPG) coupled with increasing access to the internet is opening a new paradigmatic window for a number of disciplines. Many of these have been slow to take up the challenges associated with this emergent framework, due, in no small measure, to the perception that work and play are mutually exclusive. The dominance of this dichotomy contributed to the slow uptake of the potential for these virtual worlds to be harnessed in the fields of education and employment. This reticence was due in no small measure to the technophobia that tends to characterise the adoption of new technologies within fields that have customarily eschewed an embrace.
- Full Text:
- Date Issued: 2011
Modelling of the crystallisation process of highly concentrated ammonium nitrate emulsions
- Authors: Simpson, Brenton
- Date: 2011
- Subjects: Explosives , Blasting , Chemical explosives , Ammonium nitrate
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10415 , http://hdl.handle.net/10948/d1012622 , Explosives , Blasting , Chemical explosives , Ammonium nitrate
- Description: Highly concentrated ammonium nitrate emulsions are extensively used as an explosive in the mining industry. The emulsion is made from a supercooled aqueous salt solution with various stabilisers and an organic hydrocarbon phase under vigorous stirring to room temperature. The resulting emulsion is thermodynamically unstable and tends to crystallise over time. This is not suitable for the transportation or pumping of the emulsion in its application. This study showed that the crystallisation process of highly concentrated ammonium nitrate emulsions can be influenced by varying the emulsion droplet size as well as the types and ratios of surfactants used during the preparation stage. The results showed that there were significant differences in the rheological properties of the freshly-prepared emulsion, based on both the emulsion droplet size, and the type of surfactant and ratio of surfactants used. A decrease of the emulsion droplet size resulted in the increase of the elastic character, which can be explained by more compact network organisation of droplets. In terms of the different surfactants, it was shown that the Pibsa-Imide stabilised emulsions resulted in an emulsion with the highest storage modulus over the entire strain amplitude regions as well as the highest shear stresses over the whole shear rate region. The study showed that the relatively slow emulsion crystallisation process can be studied by using powder X-ray diffraction (PXRD). The amount of amorphous and crystalline phases present in the sample can be effectively quantified by using the Partial Or No Known Crystal Structural (PONKCS) method which can model accurately the contributions of the amorphous halo. An external standard calibration method, which used a different amorphous material with the crystalline material to obtain a suitable calibration constant, was employed. The results showed that the method would quantify the amount of the fully crystallised emulsion to be between 80 and 90 percent, which was in agreement with the solid content added during sample preparation and confirmed by Thermal Gravimetric Analysis (TGA). The simultaneous TGA / DSC results were able to show the number of solid/solid peak transitions as well as the total moisture content to be around 20 percent by mass in various emulsion samples studied. The study was able to model the crystallisation by using the Avrami and Tobin kinetic relationships which are commonly used for the crystallisation processes of polymers. The Avrami relationship proved to be useful in describing the type of crystallisation that occurred. This was based on literature where the exponent parameter (n) which was between 1 and 4 would relate to different types of crystallisation models. The results of this study showed that the crystallisation process would change for the samples that had shown a longer crystallisation process. The results indicated that the samples prepared with the lower Pibsa-Urea ratio showed a more sporadic crystallisation process, whereas the samples with the higher ratio of Pibsa-Urea showed a more controlled crystallisation process. The study also considered the rheological properties of the fresh emulsion, which showed that droplet size also had an influence on the stress strain relationship of the emulsion droplets.
- Full Text:
- Date Issued: 2011
- Authors: Simpson, Brenton
- Date: 2011
- Subjects: Explosives , Blasting , Chemical explosives , Ammonium nitrate
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10415 , http://hdl.handle.net/10948/d1012622 , Explosives , Blasting , Chemical explosives , Ammonium nitrate
- Description: Highly concentrated ammonium nitrate emulsions are extensively used as an explosive in the mining industry. The emulsion is made from a supercooled aqueous salt solution with various stabilisers and an organic hydrocarbon phase under vigorous stirring to room temperature. The resulting emulsion is thermodynamically unstable and tends to crystallise over time. This is not suitable for the transportation or pumping of the emulsion in its application. This study showed that the crystallisation process of highly concentrated ammonium nitrate emulsions can be influenced by varying the emulsion droplet size as well as the types and ratios of surfactants used during the preparation stage. The results showed that there were significant differences in the rheological properties of the freshly-prepared emulsion, based on both the emulsion droplet size, and the type of surfactant and ratio of surfactants used. A decrease of the emulsion droplet size resulted in the increase of the elastic character, which can be explained by more compact network organisation of droplets. In terms of the different surfactants, it was shown that the Pibsa-Imide stabilised emulsions resulted in an emulsion with the highest storage modulus over the entire strain amplitude regions as well as the highest shear stresses over the whole shear rate region. The study showed that the relatively slow emulsion crystallisation process can be studied by using powder X-ray diffraction (PXRD). The amount of amorphous and crystalline phases present in the sample can be effectively quantified by using the Partial Or No Known Crystal Structural (PONKCS) method which can model accurately the contributions of the amorphous halo. An external standard calibration method, which used a different amorphous material with the crystalline material to obtain a suitable calibration constant, was employed. The results showed that the method would quantify the amount of the fully crystallised emulsion to be between 80 and 90 percent, which was in agreement with the solid content added during sample preparation and confirmed by Thermal Gravimetric Analysis (TGA). The simultaneous TGA / DSC results were able to show the number of solid/solid peak transitions as well as the total moisture content to be around 20 percent by mass in various emulsion samples studied. The study was able to model the crystallisation by using the Avrami and Tobin kinetic relationships which are commonly used for the crystallisation processes of polymers. The Avrami relationship proved to be useful in describing the type of crystallisation that occurred. This was based on literature where the exponent parameter (n) which was between 1 and 4 would relate to different types of crystallisation models. The results of this study showed that the crystallisation process would change for the samples that had shown a longer crystallisation process. The results indicated that the samples prepared with the lower Pibsa-Urea ratio showed a more sporadic crystallisation process, whereas the samples with the higher ratio of Pibsa-Urea showed a more controlled crystallisation process. The study also considered the rheological properties of the fresh emulsion, which showed that droplet size also had an influence on the stress strain relationship of the emulsion droplets.
- Full Text:
- Date Issued: 2011
Modelling the relationship between flow and water quality in South African rivers
- Authors: Slaughter, Andrew Robert
- Date: 2011
- Subjects: Water quality -- Measurement -- South Africa Water quality -- Mathematical models -- South Africa Streamflow -- South Africa Stream measurements -- Mathematical models -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6039 , http://hdl.handle.net/10962/d1006196
- Description: The National Water Act (Act 36 of 1998) provides for an ecological Reserve as the quantity (flow) and quality of water needed to protect aquatic ecosystems. While there are methods available to quantify the ecological Reserve in terms of flow, methods of linking flow to water quality are lacking. Therefore, the research presented in this thesis investigated various modelling techniques to estimate the effect of flow on water quality. The aims of the research presented in this thesis were: Aim 1: Can the relationship between flow and water quality be accurately represented by simple statistical models? Aim 2: Can relatively simple models accurately represent the relationship between flow and water quality? Aim 3: Can the effect of diffuse sources be omitted from a water quality model and still obtain realistic simulations, and if so under what conditions? Aim 4: Can models that solely use historical monitoring data, accurately represent the relationships between flow and water quality? In Chapter 3, simple Q-C regressions of flow and water quality were investigated using Department of Water Affairs (DWA) historical monitoring data. It was found that while flow versus salinity regressions gave good regression fits in many cases, the Q-C regression approach is limited. A mechanistic/statistical model that attempted to estimate the point and diffuse signatures of nutrients in response to flow was developed in Chapter 4 using DWA historical monitoring data. The model was verified as accurate in certain case studies using observed point loading information. In Chapter 5, statistical models that link land cover information to diffuse nutrient signatures in response to flow using DWA historical data were developed. While the model estimations are uncertain due to a lack of data, they do provide an estimation of the diffuse signature within catchments where there is flow and land cover information available. Chapter 6 investigates the extension of an existing mass-balance salinity model to estimate the effect of saline irrigation return flow on in-stream salinity. The model gave accurate salinity estimates for a low order stream with little or no irrigation within its catchment, and for a permanently flowing river within a catchment used extensively for irrigation. Chapter 7 investigated a modelling method to estimate the reaction coefficients involved in nitrification using only DWA historical monitoring data. Here, the model used flow information to estimate the residence time of nutrients within the studied river reaches. While the model obtained good estimations of nitrification for the data it was applied to, very few DWA data sets were suitable for the model. Chapter 8 investigated the ability of the in-stream model QUAL2K to estimate nutrient concentrations downstream of point and diffuse inputs of nutrients. It was found that the QUAL2K model can give accurate results in cases where point sources dominate the total nutrient inputs into a river. However, the QUAL2K simulations are too uncertain in cases where there are large diffuse source inputs of nutrients as the load of the diffuse inputs is difficult to measure in the field. This research highlights the problem of data scarcity in terms of temporal resolution as well as the range of constituents measured within DWA historical monitoring data for water quality. This thesis in addition argues that the approach of applying a number of models is preferable to applying one model to investigate the research aims, as particular models would be suited to particular circumstances, and the development of new models allowed the research aims of this thesis to be explored more thoroughly. It is also argued that simpler models that simulate a few key processes that explain the variation in observed data, are more suitable for implementing Integrated Water Resource Management (IWRM) than large comprehensive water quality models. From this research, it is clear that simple statistical models are not adequate for modelling the relationship between flow and water quality, however, relatively simple mechanistic models that simulate a limited number of processes and water quality variables, can provide accurate representations of this relationship. Under conditions where diffuse sources are not a major factor within a catchment, models that omit diffuse sources can obtain realistic simulations of the relationship between flow and water quality. Most of the models investigated in this thesis demonstrate that accurate simulations of the relationships between flow and water quality can be obtained using solely historical monitoring data.
- Full Text:
- Date Issued: 2011
- Authors: Slaughter, Andrew Robert
- Date: 2011
- Subjects: Water quality -- Measurement -- South Africa Water quality -- Mathematical models -- South Africa Streamflow -- South Africa Stream measurements -- Mathematical models -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6039 , http://hdl.handle.net/10962/d1006196
- Description: The National Water Act (Act 36 of 1998) provides for an ecological Reserve as the quantity (flow) and quality of water needed to protect aquatic ecosystems. While there are methods available to quantify the ecological Reserve in terms of flow, methods of linking flow to water quality are lacking. Therefore, the research presented in this thesis investigated various modelling techniques to estimate the effect of flow on water quality. The aims of the research presented in this thesis were: Aim 1: Can the relationship between flow and water quality be accurately represented by simple statistical models? Aim 2: Can relatively simple models accurately represent the relationship between flow and water quality? Aim 3: Can the effect of diffuse sources be omitted from a water quality model and still obtain realistic simulations, and if so under what conditions? Aim 4: Can models that solely use historical monitoring data, accurately represent the relationships between flow and water quality? In Chapter 3, simple Q-C regressions of flow and water quality were investigated using Department of Water Affairs (DWA) historical monitoring data. It was found that while flow versus salinity regressions gave good regression fits in many cases, the Q-C regression approach is limited. A mechanistic/statistical model that attempted to estimate the point and diffuse signatures of nutrients in response to flow was developed in Chapter 4 using DWA historical monitoring data. The model was verified as accurate in certain case studies using observed point loading information. In Chapter 5, statistical models that link land cover information to diffuse nutrient signatures in response to flow using DWA historical data were developed. While the model estimations are uncertain due to a lack of data, they do provide an estimation of the diffuse signature within catchments where there is flow and land cover information available. Chapter 6 investigates the extension of an existing mass-balance salinity model to estimate the effect of saline irrigation return flow on in-stream salinity. The model gave accurate salinity estimates for a low order stream with little or no irrigation within its catchment, and for a permanently flowing river within a catchment used extensively for irrigation. Chapter 7 investigated a modelling method to estimate the reaction coefficients involved in nitrification using only DWA historical monitoring data. Here, the model used flow information to estimate the residence time of nutrients within the studied river reaches. While the model obtained good estimations of nitrification for the data it was applied to, very few DWA data sets were suitable for the model. Chapter 8 investigated the ability of the in-stream model QUAL2K to estimate nutrient concentrations downstream of point and diffuse inputs of nutrients. It was found that the QUAL2K model can give accurate results in cases where point sources dominate the total nutrient inputs into a river. However, the QUAL2K simulations are too uncertain in cases where there are large diffuse source inputs of nutrients as the load of the diffuse inputs is difficult to measure in the field. This research highlights the problem of data scarcity in terms of temporal resolution as well as the range of constituents measured within DWA historical monitoring data for water quality. This thesis in addition argues that the approach of applying a number of models is preferable to applying one model to investigate the research aims, as particular models would be suited to particular circumstances, and the development of new models allowed the research aims of this thesis to be explored more thoroughly. It is also argued that simpler models that simulate a few key processes that explain the variation in observed data, are more suitable for implementing Integrated Water Resource Management (IWRM) than large comprehensive water quality models. From this research, it is clear that simple statistical models are not adequate for modelling the relationship between flow and water quality, however, relatively simple mechanistic models that simulate a limited number of processes and water quality variables, can provide accurate representations of this relationship. Under conditions where diffuse sources are not a major factor within a catchment, models that omit diffuse sources can obtain realistic simulations of the relationship between flow and water quality. Most of the models investigated in this thesis demonstrate that accurate simulations of the relationships between flow and water quality can be obtained using solely historical monitoring data.
- Full Text:
- Date Issued: 2011
Modelling trends in evapotranspiration using the MODIS LAI for selected Eastern Cape catchments
- Authors: Finca, Andiswa
- Date: 2011
- Subjects: Evapotranspiration , Evapotranspiration -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10651 , http://hdl.handle.net/10948/d1009517 , Evapotranspiration , Evapotranspiration -- South Africa -- Eastern Cape
- Description: Grassland is the dominant vegetation cover of many of the 19 Water Catchment Areas within South Africa. The inappropriate management of some of these grassland catchments by the communities that depend on them for their livelihoods, often results in overgrazed lands with low biomass or invasive alien species. The short grass maintained by grazing policies of many communities results in high storm flows that have an adverse effect on the quantity and quality of runoff and recharge. Catchment-scale water balances depend on accurate estimates of run-off, recharge and evapotranspiration (ET). This study focuses on the ET component of the catchment scale water balance and explores the effect of two different grazing strategies on ET. To achieve this, two contrasting but adjacent quaternary catchments namely: P10A (a high biomass site) and Q91C (a low biomass site) were selected within the Bushman’s River Primary catchment as primary study sites. Within each catchment, a relatively homogenous pixel of 1 km was selected, representing contrasting example of high and low intensity grazing. From an eleven year MODIS leaf area index (LAI) data stack (March 2000 – 2010), 8-day LAI values was extracted for each pixel in each catchment. Using the Penman- Monteith equation, potential evapotranspiration (ET0) was calculated using data from a nearly automatic weather station. Actual evapotranspiration was estimated by adjusting ET0 using the values extracted from the MODIS LAI product. The MODIS LAI ET (ETMODIS) obtained for the eleven year period for both 1 km pixels decreased consistently, reflecting a general trend in declining LAI throughout the Eastern Cape. The highest ETMODIS obtained from P10A was 610.3 mm (2001) and the lowest was 333.1 mm (2009). Then from Q91C the highest ET obtained was 534.7 mm (2006) and the lowest was 266.2 mm (2009). The ETMODIS results were validated for each catchment using the Open Top Chamber (OTC) which sums the water lost from vegetation and soil within the chamber. This validation was conducted during the growing season of 2010–11. Wind speed; relative humidity and temperature were measured both at the inlet and the outlet of the chamber on five clear sunny days for each 1 km pixel. ETa for the same period was compared to the OTC ET (ETOTC) using the regression analysis and a good relationship was observed with the r2 of 0.7065. The relationship observed confirmed that ETOTC closely approximates ETMODIS and that the OTC can be used as a tool to validate MODIS LAI ET on clear, low winds and sunny days. In order to demonstrate proof-of-concept for the use of this modeling of ETMODIS within a Payment for Ecosystem Services framework, the approach was applied to two other quaternary catchments under communal tenure. Within each catchment, three land use scenarios were created for each catchment to reflect potential changes in the standing aboveground biomass. For Scenario 1, the status quo was maintained; for Scenario 2, MODIS pixels representing 28 km in each catchment were selected and the LAI of these pixels was doubled; and for scenario 3, LAI was halved. ETMODIS was calculated for each scenario by adjusting the ET0 data from a nearby automatic weather station with the MODIS LAI product. The results showed that the estimated annual ETMODIS obtained from the high biomass catchment was 111 mm greater than that obtained from the low biomass catchment. When comparing between the scenarios, the annual ETMODIS obtained from scenario 2 was the highest of the 3 scenarios for both sites. These results confirm that increased leaf area results in higher annual ETMODIS. This has a positive long term impact on stream flow, as high grass biomass allows the rainfall to infiltrate the soil and be gradually released to the dams with reduced magnitude of storm flows. This approach has the potential to quantify the benefits to down-stream water users of improving above-ground biomass in catchments.
- Full Text:
- Date Issued: 2011
- Authors: Finca, Andiswa
- Date: 2011
- Subjects: Evapotranspiration , Evapotranspiration -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10651 , http://hdl.handle.net/10948/d1009517 , Evapotranspiration , Evapotranspiration -- South Africa -- Eastern Cape
- Description: Grassland is the dominant vegetation cover of many of the 19 Water Catchment Areas within South Africa. The inappropriate management of some of these grassland catchments by the communities that depend on them for their livelihoods, often results in overgrazed lands with low biomass or invasive alien species. The short grass maintained by grazing policies of many communities results in high storm flows that have an adverse effect on the quantity and quality of runoff and recharge. Catchment-scale water balances depend on accurate estimates of run-off, recharge and evapotranspiration (ET). This study focuses on the ET component of the catchment scale water balance and explores the effect of two different grazing strategies on ET. To achieve this, two contrasting but adjacent quaternary catchments namely: P10A (a high biomass site) and Q91C (a low biomass site) were selected within the Bushman’s River Primary catchment as primary study sites. Within each catchment, a relatively homogenous pixel of 1 km was selected, representing contrasting example of high and low intensity grazing. From an eleven year MODIS leaf area index (LAI) data stack (March 2000 – 2010), 8-day LAI values was extracted for each pixel in each catchment. Using the Penman- Monteith equation, potential evapotranspiration (ET0) was calculated using data from a nearly automatic weather station. Actual evapotranspiration was estimated by adjusting ET0 using the values extracted from the MODIS LAI product. The MODIS LAI ET (ETMODIS) obtained for the eleven year period for both 1 km pixels decreased consistently, reflecting a general trend in declining LAI throughout the Eastern Cape. The highest ETMODIS obtained from P10A was 610.3 mm (2001) and the lowest was 333.1 mm (2009). Then from Q91C the highest ET obtained was 534.7 mm (2006) and the lowest was 266.2 mm (2009). The ETMODIS results were validated for each catchment using the Open Top Chamber (OTC) which sums the water lost from vegetation and soil within the chamber. This validation was conducted during the growing season of 2010–11. Wind speed; relative humidity and temperature were measured both at the inlet and the outlet of the chamber on five clear sunny days for each 1 km pixel. ETa for the same period was compared to the OTC ET (ETOTC) using the regression analysis and a good relationship was observed with the r2 of 0.7065. The relationship observed confirmed that ETOTC closely approximates ETMODIS and that the OTC can be used as a tool to validate MODIS LAI ET on clear, low winds and sunny days. In order to demonstrate proof-of-concept for the use of this modeling of ETMODIS within a Payment for Ecosystem Services framework, the approach was applied to two other quaternary catchments under communal tenure. Within each catchment, three land use scenarios were created for each catchment to reflect potential changes in the standing aboveground biomass. For Scenario 1, the status quo was maintained; for Scenario 2, MODIS pixels representing 28 km in each catchment were selected and the LAI of these pixels was doubled; and for scenario 3, LAI was halved. ETMODIS was calculated for each scenario by adjusting the ET0 data from a nearby automatic weather station with the MODIS LAI product. The results showed that the estimated annual ETMODIS obtained from the high biomass catchment was 111 mm greater than that obtained from the low biomass catchment. When comparing between the scenarios, the annual ETMODIS obtained from scenario 2 was the highest of the 3 scenarios for both sites. These results confirm that increased leaf area results in higher annual ETMODIS. This has a positive long term impact on stream flow, as high grass biomass allows the rainfall to infiltrate the soil and be gradually released to the dams with reduced magnitude of storm flows. This approach has the potential to quantify the benefits to down-stream water users of improving above-ground biomass in catchments.
- Full Text:
- Date Issued: 2011
Mohair and wool fibre surface structure and lustre determination
- Ndlovu, Ntombizikhona Beaulah
- Authors: Ndlovu, Ntombizikhona Beaulah
- Date: 2011
- Subjects: Mohair and wool fibre -- Lustre
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:18484 , http://hdl.handle.net/11260/d1006641
- Description: Textiles have always been one of the essential materials for people and have a great variety of uses such as in clothing, agriculture, medical, automotive and aerospace applications. The sort of properties needed for any type of fabric basically depend on the structure of the fibre surface. Of many geometric attributes that can be used to describe the surface appearance of a fibre, yarn, or fabric sample, one of the more common is lustre. Mohair and wool fibre surface structure have been studied using optical microscopy and Atomic Force Microscopy (AFM). Optical microscopy was also used to take fibre diameter measurements. Another technique, goniophotometry, was used to make quantitative lustre measurements of mohair and wool fibres. The surface structure of mohair has got a faint pattern of scales where the scales are generally unpronounced or flat and relatively long. Wool has got a scaly surface structure where the scales overlap leading to interlocking of fibres. The scale configuration on the surface of mohair and wool fibres also differs. A qualitative connection between fibre lustre and the fibre surface structure was found. Because of its smooth surface relative to that of wool, mohair reflects a greater amount of incident light specularly whereas wool reflects most of the incident light diffusely. In general, mohair fibres have a higher lustre than wool due to its less prominent cuticle structure found on its surface. Furthermore, mohair fibres with the smallest diameters give an even higher lustre.
- Full Text:
- Date Issued: 2011
- Authors: Ndlovu, Ntombizikhona Beaulah
- Date: 2011
- Subjects: Mohair and wool fibre -- Lustre
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:18484 , http://hdl.handle.net/11260/d1006641
- Description: Textiles have always been one of the essential materials for people and have a great variety of uses such as in clothing, agriculture, medical, automotive and aerospace applications. The sort of properties needed for any type of fabric basically depend on the structure of the fibre surface. Of many geometric attributes that can be used to describe the surface appearance of a fibre, yarn, or fabric sample, one of the more common is lustre. Mohair and wool fibre surface structure have been studied using optical microscopy and Atomic Force Microscopy (AFM). Optical microscopy was also used to take fibre diameter measurements. Another technique, goniophotometry, was used to make quantitative lustre measurements of mohair and wool fibres. The surface structure of mohair has got a faint pattern of scales where the scales are generally unpronounced or flat and relatively long. Wool has got a scaly surface structure where the scales overlap leading to interlocking of fibres. The scale configuration on the surface of mohair and wool fibres also differs. A qualitative connection between fibre lustre and the fibre surface structure was found. Because of its smooth surface relative to that of wool, mohair reflects a greater amount of incident light specularly whereas wool reflects most of the incident light diffusely. In general, mohair fibres have a higher lustre than wool due to its less prominent cuticle structure found on its surface. Furthermore, mohair fibres with the smallest diameters give an even higher lustre.
- Full Text:
- Date Issued: 2011
Molecular analysis of genetic diversity in dometicated pigeonpea (Cajanus cajan (L.) Millsp.) and wild relatives
- Authors: Kassa, Mulualem Tamiru
- Date: 2011
- Subjects: Pigeon pea -- Variation Cajanus -- Variation Pigeon pea -- Genetics Cajanus -- Genetics Biodiversity Pigeon pea -- Phylogeny Cajanus -- Phylogeny Plant hybridization Plant diversity Transgenic plants
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4204 , http://hdl.handle.net/10962/d1003773
- Description: Cajanus cajan (L.) Millsp. (Pigeonpea) belongs to the Leguminosae genus Cajanus which is composed of 34 species. Pigeonpea is the only cultivated member of the genus, while the remaining species are wild relatives belonging mainly to the secondary gene pool. DNA sequence data from the nuclear ITS region and the chloroplast trnL-F spacer were utilized to investigate the phylogenetic relationships between Cajanus and five other allied genera in the subtribe Cajaninae. This study revealed the non-monophyly of Cajanus and Rhynchosia and supported the monophyly of Eriosema and Flemingia, but more sampling ,especially from the large genera of Rhynchosia and Eriosema, is recommend to adequately test the hypothesis of generic monophyly. The phylogenetic relationships within the genus Cajanus resolved Cajanus scarabaeoides (L.) Thouars as the most basal species in the Cajanus clade. The study also utilized Single Nucleotide Polymorphism (SNP) markers derived from low copy orthologous genes and genotyped using the high throughput SNP-OPA Illumina golden gate assay. The aim was to understand phylogenetic and domestication history, genetic structure, patterns of genetic diversity, gene flow and historical hybridization between Cajanus cajan (pigeonpea) and wild relatives. The neighbor-joining tree resolved well-supported clusters, which reflect the distinctiveness of species and congruence with their geographical origin. It supported the ITS based phylogeny and resolved C. scarabaeoides as basal to the Cajanus clade. The phylogenetic signal and genetic signatures revealed insights into the domestication history of pigeonpea. Our results supported Cajanus cajanifolius as the presumed progenitor of pigeonpea and we speculate that for pigeonpea there was a single major domestication event in India. Genetic admixture and historical hybridization were evident between pigeonpea and wild relatives. Abundant allelic variation and genetic diversity was found in the wild relatives, with the exception of wild species from Australia, as compared to the domesticated pigeonpea. There was a reduction of about 75% in genetic polymorphism in domesticated pigeonpea as compared to the wild relatives, indicating a severe “domestication bottleneck” during pigeonpea domestication. We discovered SNP markers associated with disease resistance (NBS-LRR) loci. The SNPs were mined in a comparison of BAC-end sequences (BES) of C. cajan and amplicons of the wild species, C. scarabaeoides. A total of ~3000 SNPs were identified from 304 BES. These SNPs could potentially be used in constructing a genetic map and for marker assisted breeding.
- Full Text:
- Date Issued: 2011
- Authors: Kassa, Mulualem Tamiru
- Date: 2011
- Subjects: Pigeon pea -- Variation Cajanus -- Variation Pigeon pea -- Genetics Cajanus -- Genetics Biodiversity Pigeon pea -- Phylogeny Cajanus -- Phylogeny Plant hybridization Plant diversity Transgenic plants
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4204 , http://hdl.handle.net/10962/d1003773
- Description: Cajanus cajan (L.) Millsp. (Pigeonpea) belongs to the Leguminosae genus Cajanus which is composed of 34 species. Pigeonpea is the only cultivated member of the genus, while the remaining species are wild relatives belonging mainly to the secondary gene pool. DNA sequence data from the nuclear ITS region and the chloroplast trnL-F spacer were utilized to investigate the phylogenetic relationships between Cajanus and five other allied genera in the subtribe Cajaninae. This study revealed the non-monophyly of Cajanus and Rhynchosia and supported the monophyly of Eriosema and Flemingia, but more sampling ,especially from the large genera of Rhynchosia and Eriosema, is recommend to adequately test the hypothesis of generic monophyly. The phylogenetic relationships within the genus Cajanus resolved Cajanus scarabaeoides (L.) Thouars as the most basal species in the Cajanus clade. The study also utilized Single Nucleotide Polymorphism (SNP) markers derived from low copy orthologous genes and genotyped using the high throughput SNP-OPA Illumina golden gate assay. The aim was to understand phylogenetic and domestication history, genetic structure, patterns of genetic diversity, gene flow and historical hybridization between Cajanus cajan (pigeonpea) and wild relatives. The neighbor-joining tree resolved well-supported clusters, which reflect the distinctiveness of species and congruence with their geographical origin. It supported the ITS based phylogeny and resolved C. scarabaeoides as basal to the Cajanus clade. The phylogenetic signal and genetic signatures revealed insights into the domestication history of pigeonpea. Our results supported Cajanus cajanifolius as the presumed progenitor of pigeonpea and we speculate that for pigeonpea there was a single major domestication event in India. Genetic admixture and historical hybridization were evident between pigeonpea and wild relatives. Abundant allelic variation and genetic diversity was found in the wild relatives, with the exception of wild species from Australia, as compared to the domesticated pigeonpea. There was a reduction of about 75% in genetic polymorphism in domesticated pigeonpea as compared to the wild relatives, indicating a severe “domestication bottleneck” during pigeonpea domestication. We discovered SNP markers associated with disease resistance (NBS-LRR) loci. The SNPs were mined in a comparison of BAC-end sequences (BES) of C. cajan and amplicons of the wild species, C. scarabaeoides. A total of ~3000 SNPs were identified from 304 BES. These SNPs could potentially be used in constructing a genetic map and for marker assisted breeding.
- Full Text:
- Date Issued: 2011