Molecular characterization, antibiograms and antibacterial activities of selected medicinal plants against some enteric pathogens
- Bisi-Johnson, Mary Adejumoke
- Authors: Bisi-Johnson, Mary Adejumoke
- Date: 2011
- Subjects: Diarrhea Diarrhea in children -- Complications Medicinal plants
- Language: English
- Type: Thesis , Doctoral , Ph D
- Identifier: vital:18475 , http://hdl.handle.net/11260/d1006643
- Description: Diarrhea diseases remain one of the greatest health problems in many parts of the world. In some cases, the disease is mild and self-limiting; however, the symptoms may be very severe in the elderly and young children (Smith and Cheasty, 1998), as well as in immune compromised patients such as HIV/AIDS patients. The disease is one of the hallmarks of HIV/AIDS in developing countries and is also a cardinal clinical manifestation of water borne infections (Obi et al., 2007). According to a World Health Organization report (WHO, 2004), diarrhea was rated second, after respiratory infections out of the eight deadliest diseases worldwide and was responsible for 1.8 million deaths per year. This infectious disease which can cause dehydration is primarily a symptom of gastrointestinal infection, but chemical irritation of the gut or non-infectious bowel disease can also result in diarrhoe. Studies have shown that the predominant causative agents of acute and persistent diarrhoe are Gram-negative rods such as Escherichia coli, Vibrio cholerae, Aeromonas, Campylobacter, Salmonella species, Shigella species, Plesiomonas shigelloides and Yersinia enterocolitica (Obi et al., 1995, 1998, 2003; Lainson and Silva, 1999; Coker et al., 2002; Oyofo et al., 2002). Aside from bacterial agents of diarrhoea, other causative pathogens include protozoa such as Giardia lamblia and Cryptosporidium parvum; viruses such as norwalk virus and rota virus. Although fungal agents such as Candida have been shown to be prevalent in children with diarrhoe (Enweani et al. 1994), a more recent study (Forbes et al., 2001), associated higher Candida counts with recent antibiotic use. Faecal concentrations of Candida were higher in patients with diarrhoe, but the study confirmed no association between faecal candida or other yeasts and diarrhoe. Norwalk viruses, calci-like viruses and rota viruses are the major viral agents of diarrhoe. According to Parashar et al., (2006), rota virus is the leading cause of diarrhoe hospitalisation among children worldwide, causing 440,000 annual deaths in children under 5 years of age.
- Full Text:
- Date Issued: 2011
- Authors: Bisi-Johnson, Mary Adejumoke
- Date: 2011
- Subjects: Diarrhea Diarrhea in children -- Complications Medicinal plants
- Language: English
- Type: Thesis , Doctoral , Ph D
- Identifier: vital:18475 , http://hdl.handle.net/11260/d1006643
- Description: Diarrhea diseases remain one of the greatest health problems in many parts of the world. In some cases, the disease is mild and self-limiting; however, the symptoms may be very severe in the elderly and young children (Smith and Cheasty, 1998), as well as in immune compromised patients such as HIV/AIDS patients. The disease is one of the hallmarks of HIV/AIDS in developing countries and is also a cardinal clinical manifestation of water borne infections (Obi et al., 2007). According to a World Health Organization report (WHO, 2004), diarrhea was rated second, after respiratory infections out of the eight deadliest diseases worldwide and was responsible for 1.8 million deaths per year. This infectious disease which can cause dehydration is primarily a symptom of gastrointestinal infection, but chemical irritation of the gut or non-infectious bowel disease can also result in diarrhoe. Studies have shown that the predominant causative agents of acute and persistent diarrhoe are Gram-negative rods such as Escherichia coli, Vibrio cholerae, Aeromonas, Campylobacter, Salmonella species, Shigella species, Plesiomonas shigelloides and Yersinia enterocolitica (Obi et al., 1995, 1998, 2003; Lainson and Silva, 1999; Coker et al., 2002; Oyofo et al., 2002). Aside from bacterial agents of diarrhoea, other causative pathogens include protozoa such as Giardia lamblia and Cryptosporidium parvum; viruses such as norwalk virus and rota virus. Although fungal agents such as Candida have been shown to be prevalent in children with diarrhoe (Enweani et al. 1994), a more recent study (Forbes et al., 2001), associated higher Candida counts with recent antibiotic use. Faecal concentrations of Candida were higher in patients with diarrhoe, but the study confirmed no association between faecal candida or other yeasts and diarrhoe. Norwalk viruses, calci-like viruses and rota viruses are the major viral agents of diarrhoe. According to Parashar et al., (2006), rota virus is the leading cause of diarrhoe hospitalisation among children worldwide, causing 440,000 annual deaths in children under 5 years of age.
- Full Text:
- Date Issued: 2011
Molecular systematics of the African snake family Lamprophiidae Fitzinger, 1843 (Serpentes: Elapoidea), with particular focus on the genera Lamprophis Fitzinger 1843 and Mehelya Csiki 1903
- Kelly, Christopher M R, Branch, William R, Broadley, Donald G, Barker, Nigel P, Villet, Martin H
- Authors: Kelly, Christopher M R , Branch, William R , Broadley, Donald G , Barker, Nigel P , Villet, Martin H
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6861 , http://hdl.handle.net/10962/d1011151
- Description: The snake family Lamprophiidae Fitzinger (Serpentes: Elapoidea) is a putatively Late Eocene radiation of nocturnal snakes endemic to the African continent. It incorporates many of the most characteristic and prolific of Africa's non-venomous snake species, including the widespread type genus Lamprophis Fitzinger, 1843 (house snakes). We used approximately 2500 bases of mitochondrial and nuclear DNA sequence data from 28 (41%) of the approximately 68 recognised lamprophiid species in nine of the eleven genera to investigate phylogenetic structure in the family and to inform taxonomy at the generic level. Cytochrome b, ND4 and tRNA gene sequences (mitochondrial) and c-mos sequences (nuclear) were analysed using Maximum Likelihood, Bayesian Inference and Maximum Parsimony methods. The genus Mehelya Csiki, 1903 was paraphyletic with respect to Gonionotophis Boulenger, 1893. To address this, the concept of Gonionotophis is expanded to include all current Mehelya species. The genus Lamprophis emerged polyphyletic: the enigmatic Lamprophis swazicus was sister to Hormonotus modestus from West Africa, and not closely related to its nominal congeners. It is moved to a new monotypic genus (Inyoka gen. nov.). The remaining Lamprophis species occur in three early-diverging lineages. (1) Lamprophis virgatus and the widely distributed Lamprophis fuliginosus species complex (which also includes Lamprophis lineatus and Lamprophis olivaceus) formed a clade for which the generic name Boaedon Duméril, Bibron & Duméril, 1854 is resurrected. (2) The water snakes (Lycodonomorphus) were nested within Lamprophis (sensu lato), sister to Lamprophis inornatus. We transfer this species to the genus Lycodonomorphus Fitzinger, 1843. (3) We restrict Lamprophis (sensu strictissimo) to a small clade of four species endemic to southern Africa: the type species of Lamprophis Fitzinger, 1843 (Lamprophis aurora) plus Lamprophis fiskii, Lamprophis fuscus and Lamprophis guttatus.
- Full Text:
- Date Issued: 2011
- Authors: Kelly, Christopher M R , Branch, William R , Broadley, Donald G , Barker, Nigel P , Villet, Martin H
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6861 , http://hdl.handle.net/10962/d1011151
- Description: The snake family Lamprophiidae Fitzinger (Serpentes: Elapoidea) is a putatively Late Eocene radiation of nocturnal snakes endemic to the African continent. It incorporates many of the most characteristic and prolific of Africa's non-venomous snake species, including the widespread type genus Lamprophis Fitzinger, 1843 (house snakes). We used approximately 2500 bases of mitochondrial and nuclear DNA sequence data from 28 (41%) of the approximately 68 recognised lamprophiid species in nine of the eleven genera to investigate phylogenetic structure in the family and to inform taxonomy at the generic level. Cytochrome b, ND4 and tRNA gene sequences (mitochondrial) and c-mos sequences (nuclear) were analysed using Maximum Likelihood, Bayesian Inference and Maximum Parsimony methods. The genus Mehelya Csiki, 1903 was paraphyletic with respect to Gonionotophis Boulenger, 1893. To address this, the concept of Gonionotophis is expanded to include all current Mehelya species. The genus Lamprophis emerged polyphyletic: the enigmatic Lamprophis swazicus was sister to Hormonotus modestus from West Africa, and not closely related to its nominal congeners. It is moved to a new monotypic genus (Inyoka gen. nov.). The remaining Lamprophis species occur in three early-diverging lineages. (1) Lamprophis virgatus and the widely distributed Lamprophis fuliginosus species complex (which also includes Lamprophis lineatus and Lamprophis olivaceus) formed a clade for which the generic name Boaedon Duméril, Bibron & Duméril, 1854 is resurrected. (2) The water snakes (Lycodonomorphus) were nested within Lamprophis (sensu lato), sister to Lamprophis inornatus. We transfer this species to the genus Lycodonomorphus Fitzinger, 1843. (3) We restrict Lamprophis (sensu strictissimo) to a small clade of four species endemic to southern Africa: the type species of Lamprophis Fitzinger, 1843 (Lamprophis aurora) plus Lamprophis fiskii, Lamprophis fuscus and Lamprophis guttatus.
- Full Text:
- Date Issued: 2011
Monetary policy transmission in South Africa: a comparative analysis of credit and exchange rate channels
- Authors: Sebitso, Nathaniel Maemu
- Date: 2011
- Subjects: Monetary policy -- South Africa , Foreign exchange market -- South Africa , Financial crises -- South Africa , South Africa -- Economic conditions , South Africa -- Economic policy , Banks and banking -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1129 , http://hdl.handle.net/10962/d1020851
- Description: This thesis focuses on monetary policy transmission and particularly seeks to examine the impact of credit and exchange rate channels of monetary policy transmission in the South African economy. South Africa's monetary policy has gone through several changes over the past thirty years. In this respect, there is a need for robust empirical evidence on the effects of these channels on inflation and output. The thesis employs a structural vector autoregressive (SVAR) model to identify monetary transmission in South Africa for the period 1994:q4 - 2008:q2. The form of the SVAR used in this thesis is based on the fact that South Africa is a small open economy, which means that external shocks are an important driver of domestic activity. The impulse responses and variance decomposition results show that the repo rate, credit and exchange rate play a role in terms of their impact on inflation and output. The dynamic responses to the identified monetary policy shock are consistent with standard theory and highlight the importance of the interest rate channel. A shock to the interest rate, increasing it by one standard deviation, results in a persistent fall in credit. The response of output is immediate as it falls and bottoms out within the second year. Inflation shows a lagged response, it is positive within the first year as the exchange rate depreciates but in subsequent quarters inflation responds negatively as expected. Inflation falls and reaches a minimum by approximately eight quarters then moves towards baseline. The exchange rate shows delayed appreciation. The shock to the repo interest rate leads to an immediate depreciation of the exchange rate in the first two quarters as output declines, followed by an appreciation in the third and sixth quarter. Due to larger error bounds the impact of the repo rate on the exchange rate could be less effective within the first two years. The impulse responses suggest that monetary policy plays an effective role in stabilising the economy in response to a credit shock, notwithstanding large standard error bounds. Hence, the monetary authority reacts by increasing the repo rate as a result of inflation. The impact of credit on output is positive but is offset to some extent by the rising repo rate. In response to the rand appreciation, the monetary authority reduces the repo rate significantly during the first year with the maximum impact in the second year and then returns to baseline thereafter. Therefore the monetary authority reduces the repo rate, probably to stabilise falling inflation. The result shows that inflation falls as a result of the rand appreciation. A shock to the exchange rate causes a rise in output, though small in magnitude, which is persistent but reaches baseline at the end of the period. This result could reflect the effects of the resultant fall in the repo rate and a persistent rise in credit over the whole period, which tends to increase output. The exchange rate shows an obvious and stronger immediate impact on inflation compared to credit impact on inflation. However, the credit shock has an obvious and stronger impact on output compared to an exchange rate impact on output. However, the large standard error bounds may imply that credit and exchange rate channels are not as effective in the short run. It is important to note that the results are based on the SVAR model estimated with percentage growth rate of the variables. The variance decomposition result is in line with the impulse responses and shows that the exchange rate and credit channels could be important transmission channels in South Africa over the chosen sample period. The exchange rate and credit shocks show a stronger effect on inflation than on output, looking at both the impulse responses and variance decomposition results. The reaction of the repo interest rate to the credit and exchange rate shocks comes out as expected. The repo rate increases as a result of an increase in the credit and falls as a result of the currency appreciation.
- Full Text:
- Date Issued: 2011
- Authors: Sebitso, Nathaniel Maemu
- Date: 2011
- Subjects: Monetary policy -- South Africa , Foreign exchange market -- South Africa , Financial crises -- South Africa , South Africa -- Economic conditions , South Africa -- Economic policy , Banks and banking -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1129 , http://hdl.handle.net/10962/d1020851
- Description: This thesis focuses on monetary policy transmission and particularly seeks to examine the impact of credit and exchange rate channels of monetary policy transmission in the South African economy. South Africa's monetary policy has gone through several changes over the past thirty years. In this respect, there is a need for robust empirical evidence on the effects of these channels on inflation and output. The thesis employs a structural vector autoregressive (SVAR) model to identify monetary transmission in South Africa for the period 1994:q4 - 2008:q2. The form of the SVAR used in this thesis is based on the fact that South Africa is a small open economy, which means that external shocks are an important driver of domestic activity. The impulse responses and variance decomposition results show that the repo rate, credit and exchange rate play a role in terms of their impact on inflation and output. The dynamic responses to the identified monetary policy shock are consistent with standard theory and highlight the importance of the interest rate channel. A shock to the interest rate, increasing it by one standard deviation, results in a persistent fall in credit. The response of output is immediate as it falls and bottoms out within the second year. Inflation shows a lagged response, it is positive within the first year as the exchange rate depreciates but in subsequent quarters inflation responds negatively as expected. Inflation falls and reaches a minimum by approximately eight quarters then moves towards baseline. The exchange rate shows delayed appreciation. The shock to the repo interest rate leads to an immediate depreciation of the exchange rate in the first two quarters as output declines, followed by an appreciation in the third and sixth quarter. Due to larger error bounds the impact of the repo rate on the exchange rate could be less effective within the first two years. The impulse responses suggest that monetary policy plays an effective role in stabilising the economy in response to a credit shock, notwithstanding large standard error bounds. Hence, the monetary authority reacts by increasing the repo rate as a result of inflation. The impact of credit on output is positive but is offset to some extent by the rising repo rate. In response to the rand appreciation, the monetary authority reduces the repo rate significantly during the first year with the maximum impact in the second year and then returns to baseline thereafter. Therefore the monetary authority reduces the repo rate, probably to stabilise falling inflation. The result shows that inflation falls as a result of the rand appreciation. A shock to the exchange rate causes a rise in output, though small in magnitude, which is persistent but reaches baseline at the end of the period. This result could reflect the effects of the resultant fall in the repo rate and a persistent rise in credit over the whole period, which tends to increase output. The exchange rate shows an obvious and stronger immediate impact on inflation compared to credit impact on inflation. However, the credit shock has an obvious and stronger impact on output compared to an exchange rate impact on output. However, the large standard error bounds may imply that credit and exchange rate channels are not as effective in the short run. It is important to note that the results are based on the SVAR model estimated with percentage growth rate of the variables. The variance decomposition result is in line with the impulse responses and shows that the exchange rate and credit channels could be important transmission channels in South Africa over the chosen sample period. The exchange rate and credit shocks show a stronger effect on inflation than on output, looking at both the impulse responses and variance decomposition results. The reaction of the repo interest rate to the credit and exchange rate shocks comes out as expected. The repo rate increases as a result of an increase in the credit and falls as a result of the currency appreciation.
- Full Text:
- Date Issued: 2011
Money attitudes and materialism among generation Y South Africans: a life-course study
- Authors: Duh, Helen Inseng
- Date: 2011
- Subjects: Consumers -- Research , Materialism , Consumer -- Behaviour , Consumer credit
- Language: English
- Type: Thesis , Doctoral , DCom
- Identifier: vital:9286 , http://hdl.handle.net/10948/d1008612 , Consumers -- Research , Materialism , Consumer -- Behaviour , Consumer credit
- Description: Materialism has long been a subject of interest to researchers. More negative than positive consequences have been reported from studies on the lifestyles of materialists. For example, increased consumer and credit card debt, shrinking saving rates, increased number of consumers filing for bankruptcy, lower levels of life satisfaction and the depletion of natural resources are reported to be emanating from the increasing levels of materialism in societies. It is thus important to investigate the factors that can be implicated for the growth of materialism. Most of the studies attempt to explain materialism at a given point in time in isolation of the events people have experienced in their early life or childhood. Realizing that this practice is a shortcoming in consumer research, there is a call that consumer behaviour, such as materialism, be studied as a function of past life experiences using the life-course approach. While few studies have applied this approach to understanding materialism, little is known about the psychological processes that link childhood family structure to materialism. It is against this background that this study used the life-course approach to study how childhood family structure affects materialism through psychological processes of perceived family resources (tangible and intangible), perceived stress from the disruptive family events, and money attitudes of Generation Y South Africans. The study also assessed the moderating role of money attitudes on the relationship between childhood family experiences and materialism. Money attitude dimensions of status, achievement, worry, security and budget were introduced to broaden the life-course study of materialism because they are reported to begin in childhood, to remain in adulthood and they function in the background of every behavioural intention and action. Generation Y (commonly reported to be born between 1977 and 1994) were the subject of this study, because the literature reviewed revealed that these emerging consumers are not only numerous (about 30 percent of South Africans are Generation Y), have considerable influence and spending power, but most have been raised in disrupted single-parent/income families. With reports from family sociologists on the outcomes of divorce and single-parenthood (for example, stress, inadequate family resources, and low self-esteem) questions were raised as to how these outcomes would affect Generation Y money attitudes and materialistic values. Ten hypotheses were formulated to empirically answer the research questions. Using quantitative methodologies based on the nature of the research questions and problems, data were collected through online questionnaire from 826 business undergraduate students from the Nelson Mandela Metropolitan and Western Cape Universities. University-aged respondents were appropriate for this study since they are ideally suited to remember their past family circumstances and must have already formed consumption habits, attitudes and values at their age. The first research problem was to evaluate how two of the life-course theoretical perspectives (i.e., family resources and stress) selected for this study would explain the materialistic values of Generation Y South Africans raised in non-intact (did not live with both biological parents before 18th birthday) and intact (lived with both biological parents before 18th birthday) family structures through the money attitudes adopted. The results showed that even though a significant difference in perceived family resources (both tangible and intangible) and stress was found between subjects raised in non-intact (or disrupted) and intact families, the difference in materialism as a whole was not significant. In terms of the three materialistic values of success, happiness and centrality, subjects raised in disrupted families significantly scored higher in the happiness dimension. For the money attitude dimensions of status, achievement, worry, budget and security they significantly scored higher in the worry money attitude. Results of the correlation analyses showed that perceived decrease in tangible (food, clothing and pocket money) family resources was a childhood factor that affected later worry money attitude to significantly and positively influence all of the three materialistic values. Perceived decreases in intangible family resources (for example, love and emotional support) negatively affected the symbolic money attitudes of status and worry, which in turn, positively affected only the happiness dimension of materialism. Perceived increase in stress positively affected all of the symbolic money attitudes of status, worry and achievement. These, in turn, positively influenced only the success and happiness materialistic values. The second research problem was based on an assessment of the moderating role of money attitudes on the childhood family experiences to materialism relationship. Using hierarchical regression analyses, it was found that only the achievement and worry money attitude dimensions moderated the family resources to materialism relationship. This means that when subjects hold higher worry and achievement money attitudes, an increase in family resources (tangible and intangible) will have less effect in reducing materialistic tendencies. For the stress to materialism relationship, only the worry money attitude dimension had a moderating effect, meaning that when higher worry money attitude is held, an increase in stress from family disruptions would have a greater effect in increasing materialistic tendencies. None of the five money attitude dimensions did, however, moderate the childhood family structure to materialism relationship. The results of this study do not only have theoretical implications, but also provide valuable information to consumer-interest groups, banks and retailers, especially in terms of the money attitudes of Generation Y consumers in South Africa.
- Full Text:
- Date Issued: 2011
- Authors: Duh, Helen Inseng
- Date: 2011
- Subjects: Consumers -- Research , Materialism , Consumer -- Behaviour , Consumer credit
- Language: English
- Type: Thesis , Doctoral , DCom
- Identifier: vital:9286 , http://hdl.handle.net/10948/d1008612 , Consumers -- Research , Materialism , Consumer -- Behaviour , Consumer credit
- Description: Materialism has long been a subject of interest to researchers. More negative than positive consequences have been reported from studies on the lifestyles of materialists. For example, increased consumer and credit card debt, shrinking saving rates, increased number of consumers filing for bankruptcy, lower levels of life satisfaction and the depletion of natural resources are reported to be emanating from the increasing levels of materialism in societies. It is thus important to investigate the factors that can be implicated for the growth of materialism. Most of the studies attempt to explain materialism at a given point in time in isolation of the events people have experienced in their early life or childhood. Realizing that this practice is a shortcoming in consumer research, there is a call that consumer behaviour, such as materialism, be studied as a function of past life experiences using the life-course approach. While few studies have applied this approach to understanding materialism, little is known about the psychological processes that link childhood family structure to materialism. It is against this background that this study used the life-course approach to study how childhood family structure affects materialism through psychological processes of perceived family resources (tangible and intangible), perceived stress from the disruptive family events, and money attitudes of Generation Y South Africans. The study also assessed the moderating role of money attitudes on the relationship between childhood family experiences and materialism. Money attitude dimensions of status, achievement, worry, security and budget were introduced to broaden the life-course study of materialism because they are reported to begin in childhood, to remain in adulthood and they function in the background of every behavioural intention and action. Generation Y (commonly reported to be born between 1977 and 1994) were the subject of this study, because the literature reviewed revealed that these emerging consumers are not only numerous (about 30 percent of South Africans are Generation Y), have considerable influence and spending power, but most have been raised in disrupted single-parent/income families. With reports from family sociologists on the outcomes of divorce and single-parenthood (for example, stress, inadequate family resources, and low self-esteem) questions were raised as to how these outcomes would affect Generation Y money attitudes and materialistic values. Ten hypotheses were formulated to empirically answer the research questions. Using quantitative methodologies based on the nature of the research questions and problems, data were collected through online questionnaire from 826 business undergraduate students from the Nelson Mandela Metropolitan and Western Cape Universities. University-aged respondents were appropriate for this study since they are ideally suited to remember their past family circumstances and must have already formed consumption habits, attitudes and values at their age. The first research problem was to evaluate how two of the life-course theoretical perspectives (i.e., family resources and stress) selected for this study would explain the materialistic values of Generation Y South Africans raised in non-intact (did not live with both biological parents before 18th birthday) and intact (lived with both biological parents before 18th birthday) family structures through the money attitudes adopted. The results showed that even though a significant difference in perceived family resources (both tangible and intangible) and stress was found between subjects raised in non-intact (or disrupted) and intact families, the difference in materialism as a whole was not significant. In terms of the three materialistic values of success, happiness and centrality, subjects raised in disrupted families significantly scored higher in the happiness dimension. For the money attitude dimensions of status, achievement, worry, budget and security they significantly scored higher in the worry money attitude. Results of the correlation analyses showed that perceived decrease in tangible (food, clothing and pocket money) family resources was a childhood factor that affected later worry money attitude to significantly and positively influence all of the three materialistic values. Perceived decreases in intangible family resources (for example, love and emotional support) negatively affected the symbolic money attitudes of status and worry, which in turn, positively affected only the happiness dimension of materialism. Perceived increase in stress positively affected all of the symbolic money attitudes of status, worry and achievement. These, in turn, positively influenced only the success and happiness materialistic values. The second research problem was based on an assessment of the moderating role of money attitudes on the childhood family experiences to materialism relationship. Using hierarchical regression analyses, it was found that only the achievement and worry money attitude dimensions moderated the family resources to materialism relationship. This means that when subjects hold higher worry and achievement money attitudes, an increase in family resources (tangible and intangible) will have less effect in reducing materialistic tendencies. For the stress to materialism relationship, only the worry money attitude dimension had a moderating effect, meaning that when higher worry money attitude is held, an increase in stress from family disruptions would have a greater effect in increasing materialistic tendencies. None of the five money attitude dimensions did, however, moderate the childhood family structure to materialism relationship. The results of this study do not only have theoretical implications, but also provide valuable information to consumer-interest groups, banks and retailers, especially in terms of the money attitudes of Generation Y consumers in South Africa.
- Full Text:
- Date Issued: 2011
Monitoring and evaluation indicators of the HIV & AIDS programme in Grahamstown's public sector health care system
- Authors: Mahasele, Phehello Anthony
- Date: 2011
- Subjects: AIDS (Disease) -- Patients -- Services for -- South Africa -- Grahamstown -- Evaluation HIV-positive persons -- Services for -- South Africa -- Grahamstown -- Evaluation Public health -- South Africa -- Grahamstown -- Evaluation Antiretroviral agents -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: vital:3770 , http://hdl.handle.net/10962/d1003248
- Description: South Africa is one of the countries hardest hit with the Human Immunodeficiency Virus (HIV) and Acquired Immuno Deficiency Syndrome (AIDS) epidemic. In response to the epidemic, the South African government adopted the Comprehensive HIV & AIDS Care, Management and Treatment programme strategic plan (CCMT) in 2000 (1) and developed the Operational Plan for CCMT for antiretroviral therapy rollout in 2003 (2). In order to monitor the progress of the implementation of CCMT, the National Department of Health (NDOH) adopted the Monitoring and Evaluation (M & E) framework in 2004 (3). The aim of this study was to assess the HIV & AIDS programme in Grahamstown‘s public sector health care system by using the national M & E indicators of the HIV & AIDS programme. The national M & E framework was used as the data collection tool and available information was collected from various sources such as the District Health Office (DHO), Primary Health Care (PHC) office, accredited antiretroviral sites and the provincial pharmaceutical depot. Group interviews were conducted with key stakeholder health care professionals at the District Health Office, Primary Health Care office, Settlers Hospital and the provincial Department of Health personnel. A one-on-one interview was conducted with the Deputy Director of HIV & AIDS Directorate, monitoring and evaluation in the National Department of Health. Available indicators such as budget and expenditure including antiretroviral procurement; human resources; nutrition-related indicators; prevention care and treatment indicators were collected. A group interview was conducted to document current practices, or where there was a lack of documentation, for indicators such as traditional medicines and pharmacovigilance. Most of the national M & E indicators are not required to be collected or collated by the district because the reporting format designed by the provincial Department of Health is different. Facilities, districts and provinces in South Africa are at different levels of implementation of the antiretroviral programme and hence a common format of the M & E indicators is not used by all provinces. Uniform data collection is not achieved due to human resources‘ constraints and other challenges such as continued use of manual reporting systems by the clinics. Districts are expected to report according to the formats drawn up by the provincial Department of Health (DOH) and there is a lack of awareness regarding the national M & E document amongst the Grahamstown Health Care Professionals. There is a need for training on the use of the M & E national framework so that the HCPs at the primary and secondary levels of the health care system are proficient with the process of M & E, and can provide inputs as well as take ownership of the process. The establishment of an M & E unit in Grahamstown is essential so that data collection and submission of the HIV & AIDS programme in the public sector according to the National M & E framework is addressed. However, despite all constraints and challenges in the public sector health care system in Grahamstown, available human and financial resources are being used effectively to maintain the HIV & AIDS programme.
- Full Text:
- Date Issued: 2011
- Authors: Mahasele, Phehello Anthony
- Date: 2011
- Subjects: AIDS (Disease) -- Patients -- Services for -- South Africa -- Grahamstown -- Evaluation HIV-positive persons -- Services for -- South Africa -- Grahamstown -- Evaluation Public health -- South Africa -- Grahamstown -- Evaluation Antiretroviral agents -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: vital:3770 , http://hdl.handle.net/10962/d1003248
- Description: South Africa is one of the countries hardest hit with the Human Immunodeficiency Virus (HIV) and Acquired Immuno Deficiency Syndrome (AIDS) epidemic. In response to the epidemic, the South African government adopted the Comprehensive HIV & AIDS Care, Management and Treatment programme strategic plan (CCMT) in 2000 (1) and developed the Operational Plan for CCMT for antiretroviral therapy rollout in 2003 (2). In order to monitor the progress of the implementation of CCMT, the National Department of Health (NDOH) adopted the Monitoring and Evaluation (M & E) framework in 2004 (3). The aim of this study was to assess the HIV & AIDS programme in Grahamstown‘s public sector health care system by using the national M & E indicators of the HIV & AIDS programme. The national M & E framework was used as the data collection tool and available information was collected from various sources such as the District Health Office (DHO), Primary Health Care (PHC) office, accredited antiretroviral sites and the provincial pharmaceutical depot. Group interviews were conducted with key stakeholder health care professionals at the District Health Office, Primary Health Care office, Settlers Hospital and the provincial Department of Health personnel. A one-on-one interview was conducted with the Deputy Director of HIV & AIDS Directorate, monitoring and evaluation in the National Department of Health. Available indicators such as budget and expenditure including antiretroviral procurement; human resources; nutrition-related indicators; prevention care and treatment indicators were collected. A group interview was conducted to document current practices, or where there was a lack of documentation, for indicators such as traditional medicines and pharmacovigilance. Most of the national M & E indicators are not required to be collected or collated by the district because the reporting format designed by the provincial Department of Health is different. Facilities, districts and provinces in South Africa are at different levels of implementation of the antiretroviral programme and hence a common format of the M & E indicators is not used by all provinces. Uniform data collection is not achieved due to human resources‘ constraints and other challenges such as continued use of manual reporting systems by the clinics. Districts are expected to report according to the formats drawn up by the provincial Department of Health (DOH) and there is a lack of awareness regarding the national M & E document amongst the Grahamstown Health Care Professionals. There is a need for training on the use of the M & E national framework so that the HCPs at the primary and secondary levels of the health care system are proficient with the process of M & E, and can provide inputs as well as take ownership of the process. The establishment of an M & E unit in Grahamstown is essential so that data collection and submission of the HIV & AIDS programme in the public sector according to the National M & E framework is addressed. However, despite all constraints and challenges in the public sector health care system in Grahamstown, available human and financial resources are being used effectively to maintain the HIV & AIDS programme.
- Full Text:
- Date Issued: 2011
Morphology and identification of first instars of African blow flies (Diptera: Calliphoridae) commonly of forensic importance
- Szpila, Krzysztof, Villet, Martin H
- Authors: Szpila, Krzysztof , Villet, Martin H
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442225 , vital:73968 , https://doi.org/10.1603/ME10238
- Description: Scanning electron microscopy images of the first instars of Calliphora croceipalpis Jaennicke, 1876; Chrysomya chloropyga (Wiedemann, 1818); Chrysomya marginalis (Wiedemann, 1830); and Chrysomya putoria (Wiedemann, 1830) (Diptera: Calliphoridae) are presented for the first time, and the following morphological structures are documented: pseudocephalon, antenna, maxillary palpus, facial mask, labial lobe, thoracic and abdominal spinulation, spiracular field, posterior spiracles, and anal pads. Light microscopy photographs and line illustrations are provided for the cephaloskeleton in lateral and ventral views, and the “ectostomal sclerite” and “chitinized teeth” of the cephaloskeleton are recognized as integral parts of the mouthhooks. New diagnostic features of the cephaloskeleton and the spinulation of the abdominal segments are described. These results allow refinement, clarification, and correction of earlier descriptions, which are reviewed. The relative taxonomic importance of various morphological characters of the first instars of necrophagous blow flies is discussed, and details of the cephaloskeleton and the spinulation of the abdominal segments are highlighted as the characters most useful for species identification. Finally, a key for identifying first instars of common African carrion blow flies is provided.
- Full Text:
- Date Issued: 2011
- Authors: Szpila, Krzysztof , Villet, Martin H
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442225 , vital:73968 , https://doi.org/10.1603/ME10238
- Description: Scanning electron microscopy images of the first instars of Calliphora croceipalpis Jaennicke, 1876; Chrysomya chloropyga (Wiedemann, 1818); Chrysomya marginalis (Wiedemann, 1830); and Chrysomya putoria (Wiedemann, 1830) (Diptera: Calliphoridae) are presented for the first time, and the following morphological structures are documented: pseudocephalon, antenna, maxillary palpus, facial mask, labial lobe, thoracic and abdominal spinulation, spiracular field, posterior spiracles, and anal pads. Light microscopy photographs and line illustrations are provided for the cephaloskeleton in lateral and ventral views, and the “ectostomal sclerite” and “chitinized teeth” of the cephaloskeleton are recognized as integral parts of the mouthhooks. New diagnostic features of the cephaloskeleton and the spinulation of the abdominal segments are described. These results allow refinement, clarification, and correction of earlier descriptions, which are reviewed. The relative taxonomic importance of various morphological characters of the first instars of necrophagous blow flies is discussed, and details of the cephaloskeleton and the spinulation of the abdominal segments are highlighted as the characters most useful for species identification. Finally, a key for identifying first instars of common African carrion blow flies is provided.
- Full Text:
- Date Issued: 2011
Motivations of international trophy hunters choosing to hunt in South Africa
- Authors: Mulder, Attilia Cesira
- Date: 2011
- Subjects: Hunting trophies -- South Africa , Hunting -- South Africa , Travelers
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9360 , http://hdl.handle.net/10948/1328 , Hunting trophies -- South Africa , Hunting -- South Africa , Travelers
- Description: In travel research, it is generally accepted that push factors are the motivations that prompt an individual to travel, and pull factors are those by which the individual is enticed by the attractiveness of the destination, once the decision to travel has been made. Having this been said, this research examined the motivations of international trophy hunters and why they chose to hunt in South Africa. The empirical data were collected by means of a postal survey. Two thousand self-administered questionnaires were distributed to overseas hunters who had previously visited South Africa to participate in a hunting safari. One hundred and ninety one questionnaires were suitable for the data analysis. Results of the principal component factor analysis yielded six push motivational dimensions that influenced an individual to participate in trophy hunting, and three pull motivational dimensions that encouraged hunters to hunt in South Africa. Multivariate analyses (MANOVA) were conducted to examine differences between the push and pull factors across various socio-demographic characteristics. Where differences in the MANOVA were found, additional analyses were conducted to examine differences between push and pull factors on the socio-demographic subgroups. Pearson's correlation coefficient was used to measure the degree of interrelationships among push and pull factors for socio-demographic factors. To address the objectives of the current study, five postulations were formulated. The first postulation revealed that personal, psychological needs and values, such as status, family, social interaction, exercise and challenge, were the main factors that push individuals to participate in trophy hunting. Postulation 2 indicated that a number of factors pull overseas hunters to hunt in South Africa namely, nature/scenery, fantasy and information sources - particularly recommendations by other hunters. The third postulation was confirmed namely that country of residence, age, gender, occupation and income have an influence on push and pull factors of motivation. Postulation 4 partly confirmed that a positive relationship exists between a number of push and pull factors of motivation. Lastly, postulation 5 verified that socio-demographics do have an influence on the relationship between push and pull factors of motivation. Results of the study thus provide destination/tourism/marketing managers and/or professionals within the hunting industry with a better understanding of hunters' travel motivation and behavior.
- Full Text:
- Date Issued: 2011
- Authors: Mulder, Attilia Cesira
- Date: 2011
- Subjects: Hunting trophies -- South Africa , Hunting -- South Africa , Travelers
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9360 , http://hdl.handle.net/10948/1328 , Hunting trophies -- South Africa , Hunting -- South Africa , Travelers
- Description: In travel research, it is generally accepted that push factors are the motivations that prompt an individual to travel, and pull factors are those by which the individual is enticed by the attractiveness of the destination, once the decision to travel has been made. Having this been said, this research examined the motivations of international trophy hunters and why they chose to hunt in South Africa. The empirical data were collected by means of a postal survey. Two thousand self-administered questionnaires were distributed to overseas hunters who had previously visited South Africa to participate in a hunting safari. One hundred and ninety one questionnaires were suitable for the data analysis. Results of the principal component factor analysis yielded six push motivational dimensions that influenced an individual to participate in trophy hunting, and three pull motivational dimensions that encouraged hunters to hunt in South Africa. Multivariate analyses (MANOVA) were conducted to examine differences between the push and pull factors across various socio-demographic characteristics. Where differences in the MANOVA were found, additional analyses were conducted to examine differences between push and pull factors on the socio-demographic subgroups. Pearson's correlation coefficient was used to measure the degree of interrelationships among push and pull factors for socio-demographic factors. To address the objectives of the current study, five postulations were formulated. The first postulation revealed that personal, psychological needs and values, such as status, family, social interaction, exercise and challenge, were the main factors that push individuals to participate in trophy hunting. Postulation 2 indicated that a number of factors pull overseas hunters to hunt in South Africa namely, nature/scenery, fantasy and information sources - particularly recommendations by other hunters. The third postulation was confirmed namely that country of residence, age, gender, occupation and income have an influence on push and pull factors of motivation. Postulation 4 partly confirmed that a positive relationship exists between a number of push and pull factors of motivation. Lastly, postulation 5 verified that socio-demographics do have an influence on the relationship between push and pull factors of motivation. Results of the study thus provide destination/tourism/marketing managers and/or professionals within the hunting industry with a better understanding of hunters' travel motivation and behavior.
- Full Text:
- Date Issued: 2011
Mutational analysis of the PacC binding sites within the aflR promoter in Aspergillus flavus
- Authors: Suleman, Essa
- Date: 2011
- Subjects: Mutation (Biology) , Genetic regulation , Proteins -- Synthesis , Microbiological synthesis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10336 , http://hdl.handle.net/10948/d1012683 , Mutation (Biology) , Genetic regulation , Proteins -- Synthesis , Microbiological synthesis
- Description: It is generally known that media containing simple sugars (sucrose, glucose) and organic nitrogen sources (ammonium) when buffered to acidic pH stimulates aflatoxin production in Aspergillus flavus & A. parasiticus while lactose, nitrate and an alkaline pH inhibit aflatoxin biosynthesis. It has been shown that pH of the growth medium is the most important regulatory factor for aflatoxin biosynthesis since media containing stimulatory carbon and/or nitrogen sources (sucrose and ammonia) do not enhance aflatoxin (or sterigmatocystin) production at alkaline pH. RNA interference (in A. flavus) of the pH regulatory transcription factor, PacC, resulted in aflatoxin production under acidic and alkaline pH conditions whilst wildtype Aspergillus flavus produced aflatoxins only under acidic conditions. This conclusively proved that PacC negatively regulates aflatoxin production at alkaline pH in A. flavus. However the exact mechanism involved in PacC repression of aflatoxin biosynthesis at alkaline pH still remains unknown. The AflR protein is essential for expression of several genes in the aflatoxin biosynthetic cluster. In the current study, sequence analysis of the aflR promoter indicated the presence of two putative PacC binding sites within the aflR promoter of A. flavus 3357WT located at positions -162 and -487 bp from the start codon. The presence of the PacC binding sites in the aflR promoter indicated a possible link between aflR expression and PacC regulation under alkaline conditions. Thus, in this study, it was hypothesized that at alkaline pH, PacC inhibits aflR expression by binding to one or both of the PacC binding sites within the aflR promoter. This in turn, would result in inhibition of aflatoxin biosynthesis since expression of several aflatoxin biosynthetic pathway genes is dependent on activation by AflR. The aim and objective of this study was to test the validity of this hypothesis i.e. that at alkaline pH PacC binds to one or both of its recognition sites within the aflR promoter thereby inhibiting aflR expression which subsequently would result in inhibition of aflatoxin biosynthesis. This was done by first mutating each individual and then both PacC binding sites in the A. flavus 3357 aflR promoter via Single-Joint PCR (SJ-PCR) and fusing the wildtype and each mutated aflR promoter to the Green Fluorescent Protein (gfp) gene and the trpC terminator to yield a functional expression vector. These constructs were then transformed into A. flavus 3357.5. Positive transformants were confirmed to express GFP by fluorescence microscopy and spectrofluorometry. Quantification of GFP protein levels of the various transformants in this study indicated that PacC negatively regulated aflR promoter activity at alkaline pH. RT-qPCR was performed on positive transformants after growth on SLS medium at acidic and alkaline pH to determine if PacC negatively regulated aflR promoter activity at alkaline pH and to determine whether PacC binds preferentially to one or both recognition sites within the aflR promoter. RT-qPCR analysis suggest that PacC binds non-preferentially to both recognition sites within the aflR promoter on sucrose and lactose media at alkaline pH, although mutation of PacC binding site 2 results in a slightly higher expression compared to mutation of PacC binding site 1. Increasing the concentration of an aflatoxin conducive nitrogen source stimulated aflR promoter activity but this was not sufficient to overcome negative regulation by PacC. It is generally known that repression of aflR expression results in repression of aflatoxin biosynthesis irrespective of pH. The results of this study strongly suggest that PacC negatively regulates aflR promoter activity at alkaline pH by binding to one or both PacC recognition sites within the aflR promoter. Since aflR promoter activity is repressed by PacC at alkaline pH, this substantiates the hypothesis that PacC represses aflatoxin biosynthesis by inhibiting expression of aflR. Furthermore, the results of this study indicated that there may be some PacC protein present in the active form at acidic pH irrespective of the carbon source and nitrogen source used in the growth medium. RT-qPCR analysis indicated that any active PacC present at acidic pH may cause repression of the aflR promoter based on the position of the PacC binding site relative to the aflR start codon, although it appears that PacC may have a higher affinity for PacC binding site 2 (which is closer to the aflR start codon).
- Full Text:
- Date Issued: 2011
- Authors: Suleman, Essa
- Date: 2011
- Subjects: Mutation (Biology) , Genetic regulation , Proteins -- Synthesis , Microbiological synthesis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10336 , http://hdl.handle.net/10948/d1012683 , Mutation (Biology) , Genetic regulation , Proteins -- Synthesis , Microbiological synthesis
- Description: It is generally known that media containing simple sugars (sucrose, glucose) and organic nitrogen sources (ammonium) when buffered to acidic pH stimulates aflatoxin production in Aspergillus flavus & A. parasiticus while lactose, nitrate and an alkaline pH inhibit aflatoxin biosynthesis. It has been shown that pH of the growth medium is the most important regulatory factor for aflatoxin biosynthesis since media containing stimulatory carbon and/or nitrogen sources (sucrose and ammonia) do not enhance aflatoxin (or sterigmatocystin) production at alkaline pH. RNA interference (in A. flavus) of the pH regulatory transcription factor, PacC, resulted in aflatoxin production under acidic and alkaline pH conditions whilst wildtype Aspergillus flavus produced aflatoxins only under acidic conditions. This conclusively proved that PacC negatively regulates aflatoxin production at alkaline pH in A. flavus. However the exact mechanism involved in PacC repression of aflatoxin biosynthesis at alkaline pH still remains unknown. The AflR protein is essential for expression of several genes in the aflatoxin biosynthetic cluster. In the current study, sequence analysis of the aflR promoter indicated the presence of two putative PacC binding sites within the aflR promoter of A. flavus 3357WT located at positions -162 and -487 bp from the start codon. The presence of the PacC binding sites in the aflR promoter indicated a possible link between aflR expression and PacC regulation under alkaline conditions. Thus, in this study, it was hypothesized that at alkaline pH, PacC inhibits aflR expression by binding to one or both of the PacC binding sites within the aflR promoter. This in turn, would result in inhibition of aflatoxin biosynthesis since expression of several aflatoxin biosynthetic pathway genes is dependent on activation by AflR. The aim and objective of this study was to test the validity of this hypothesis i.e. that at alkaline pH PacC binds to one or both of its recognition sites within the aflR promoter thereby inhibiting aflR expression which subsequently would result in inhibition of aflatoxin biosynthesis. This was done by first mutating each individual and then both PacC binding sites in the A. flavus 3357 aflR promoter via Single-Joint PCR (SJ-PCR) and fusing the wildtype and each mutated aflR promoter to the Green Fluorescent Protein (gfp) gene and the trpC terminator to yield a functional expression vector. These constructs were then transformed into A. flavus 3357.5. Positive transformants were confirmed to express GFP by fluorescence microscopy and spectrofluorometry. Quantification of GFP protein levels of the various transformants in this study indicated that PacC negatively regulated aflR promoter activity at alkaline pH. RT-qPCR was performed on positive transformants after growth on SLS medium at acidic and alkaline pH to determine if PacC negatively regulated aflR promoter activity at alkaline pH and to determine whether PacC binds preferentially to one or both recognition sites within the aflR promoter. RT-qPCR analysis suggest that PacC binds non-preferentially to both recognition sites within the aflR promoter on sucrose and lactose media at alkaline pH, although mutation of PacC binding site 2 results in a slightly higher expression compared to mutation of PacC binding site 1. Increasing the concentration of an aflatoxin conducive nitrogen source stimulated aflR promoter activity but this was not sufficient to overcome negative regulation by PacC. It is generally known that repression of aflR expression results in repression of aflatoxin biosynthesis irrespective of pH. The results of this study strongly suggest that PacC negatively regulates aflR promoter activity at alkaline pH by binding to one or both PacC recognition sites within the aflR promoter. Since aflR promoter activity is repressed by PacC at alkaline pH, this substantiates the hypothesis that PacC represses aflatoxin biosynthesis by inhibiting expression of aflR. Furthermore, the results of this study indicated that there may be some PacC protein present in the active form at acidic pH irrespective of the carbon source and nitrogen source used in the growth medium. RT-qPCR analysis indicated that any active PacC present at acidic pH may cause repression of the aflR promoter based on the position of the PacC binding site relative to the aflR start codon, although it appears that PacC may have a higher affinity for PacC binding site 2 (which is closer to the aflR start codon).
- Full Text:
- Date Issued: 2011
My other - my self: post-Cartesian ontological possibilities in the fiction of J M Coetzee
- Authors: Mfune, Damazio Laston
- Date: 2011
- Subjects: Coetzee, J. M., 1940- -- Criticism and interpretation Self in literature Identity (Psychology) in literature Consciousness in literature Intersubjectivity in literature Ontology in literature Metaphysics in literature South African fiction (English) -- 20th century -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2246 , http://hdl.handle.net/10962/d1002289
- Description: The central argument of my study is that, among other matters, in his works, J.M. Coetzee could be said to demonstrate that the known Self is an embodied being and is not autonomous. With regard to the latter contention, Coetzee intimates that any two Subjects are implicated in each other’s subjectivities in a reciprocal process that involves what Derek Attridge has called “irruptions of otherness” (2005: xii) into the Subject’s subjectivity. These irruptions, which happen during the encounter, lead to a double loss of autonomy for each Subject and this phenomenon renders the relationship between Subjects non-dichotomus or non-binaric. In other words, the Subject does not produce the contents of his or her consciousness in a sui generis and ex nihilo fashion, and his or her ontological indebtedness to the Other constitutes his or her first loss of autonomy. As for those Others that do possess consciousness, the Subject is implicated in their consciousness and this constitutes the Subject’s second loss of autonomy. These losses counter the near solipsistic Nagelian neo-Cartesianism and paves the way for imagining both intra- and inter-species “intersubjectivity”. It is my view that this double loss of autonomy accounts for the sympathetic and empathetic imagination that we encounter in Coetzee’s fiction. Following Coetzee’s intimations of intersubjectivity through irruptions of otherness, what I see as my contribution to studies on this author’s work through this study is the link I have established between the physicalist strain within the philosophy of mind (whose central thesis is that consciousness is an embodied phenomenon) and a modified Kantian “metaphysics”, especially Immanuel Kant’s conception of concepts as comprising form and content. I have deployed this conception in demonstrating the Subject’s ontological indebtedness to external sources of the content part of consciousness. And, through the Husserlian concept of intentionality, and Kant’s (1929: 27) observation that we cannot have appearances without something that appears, I have linked the Subject to the sources of his or her content and thereby also demonstrated that the Subject is not eternally separated or alienated from those sources. Instead, the Subject is not simply contiguous but coterminous and co-extensive, albeit in a mediated way, with the external sources of the content part of his or her consciousness. Thus, while accepting the thesis of the Other’s radical otherness, I modify the thesis of the Other’s radical exteriority. Ultimately, then, ontologically speaking, the Coetzeean project could be described as one of embodying and grounding the supposedly autonomous, solipsistic and freefloating/disembodied Cartesian Subject. This he does by alerting this Subject, first and foremost, to its embodiedness and, further to that, pointing out its ontological indebtedness to its Others and its implication in the Others’s consciousnesses and so prevent it from continuing with its imperialistic and ecological barbarities. However, ethically speaking, beyond the reciprocal ethics that arises from mutual ontological indebtedness and implication, it is the selflessness that characterises a cruciform logic that comes across as the epitome of Coetzeean ethics.
- Full Text:
- Date Issued: 2011
- Authors: Mfune, Damazio Laston
- Date: 2011
- Subjects: Coetzee, J. M., 1940- -- Criticism and interpretation Self in literature Identity (Psychology) in literature Consciousness in literature Intersubjectivity in literature Ontology in literature Metaphysics in literature South African fiction (English) -- 20th century -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2246 , http://hdl.handle.net/10962/d1002289
- Description: The central argument of my study is that, among other matters, in his works, J.M. Coetzee could be said to demonstrate that the known Self is an embodied being and is not autonomous. With regard to the latter contention, Coetzee intimates that any two Subjects are implicated in each other’s subjectivities in a reciprocal process that involves what Derek Attridge has called “irruptions of otherness” (2005: xii) into the Subject’s subjectivity. These irruptions, which happen during the encounter, lead to a double loss of autonomy for each Subject and this phenomenon renders the relationship between Subjects non-dichotomus or non-binaric. In other words, the Subject does not produce the contents of his or her consciousness in a sui generis and ex nihilo fashion, and his or her ontological indebtedness to the Other constitutes his or her first loss of autonomy. As for those Others that do possess consciousness, the Subject is implicated in their consciousness and this constitutes the Subject’s second loss of autonomy. These losses counter the near solipsistic Nagelian neo-Cartesianism and paves the way for imagining both intra- and inter-species “intersubjectivity”. It is my view that this double loss of autonomy accounts for the sympathetic and empathetic imagination that we encounter in Coetzee’s fiction. Following Coetzee’s intimations of intersubjectivity through irruptions of otherness, what I see as my contribution to studies on this author’s work through this study is the link I have established between the physicalist strain within the philosophy of mind (whose central thesis is that consciousness is an embodied phenomenon) and a modified Kantian “metaphysics”, especially Immanuel Kant’s conception of concepts as comprising form and content. I have deployed this conception in demonstrating the Subject’s ontological indebtedness to external sources of the content part of consciousness. And, through the Husserlian concept of intentionality, and Kant’s (1929: 27) observation that we cannot have appearances without something that appears, I have linked the Subject to the sources of his or her content and thereby also demonstrated that the Subject is not eternally separated or alienated from those sources. Instead, the Subject is not simply contiguous but coterminous and co-extensive, albeit in a mediated way, with the external sources of the content part of his or her consciousness. Thus, while accepting the thesis of the Other’s radical otherness, I modify the thesis of the Other’s radical exteriority. Ultimately, then, ontologically speaking, the Coetzeean project could be described as one of embodying and grounding the supposedly autonomous, solipsistic and freefloating/disembodied Cartesian Subject. This he does by alerting this Subject, first and foremost, to its embodiedness and, further to that, pointing out its ontological indebtedness to its Others and its implication in the Others’s consciousnesses and so prevent it from continuing with its imperialistic and ecological barbarities. However, ethically speaking, beyond the reciprocal ethics that arises from mutual ontological indebtedness and implication, it is the selflessness that characterises a cruciform logic that comes across as the epitome of Coetzeean ethics.
- Full Text:
- Date Issued: 2011
Nanomaterial modified electrodes : optimization of voltammetric sensors for pharmaceutical and industrial application
- Authors: Brimecombe, Rory Dennis
- Date: 2011
- Subjects: Voltammetry , Electrochemistry , Nanotubes , Nanostructured materials
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4101 , http://hdl.handle.net/10962/d1009721
- Description: Nanomaterials, in particular carbon nanotubes have been shown to exhibit favourable properties for the enhancement of electrochemical detection of target analytes in complex matrices. There is however scope for improvement in terms of the optimization thereof in electrochemical sensors surface modification. The aim of this thesis was to examine methods that would result in increased current response, lowered passivation and application of such modified surfaces with application to pharmaceutically and industrially relevant analytes. Current methods for enhancing the performance of carbon nanotubes include acid functionalization which not only increases the hydrophilicity of the nanotubes, and consequently their ability to provide stable (aqueous) suspensions, but also introduces electrochemically active sites. This particular approach is however not normalized in the literature. Over-exposure to acid treatment results in loss of structural integrity of the carbon nanotubes, and as such a fine balance exists between achieving these dual outcomes. Guided by high resolution scanning electron microscopy, atomic force microscopy, voltammetric and impedance studies, this thesis examined the role of the length of time of the acid functionalization process as well as the impact of activation of carbon nanotubes and fullerenes on electrochemical sensor performance. Based on desired charge transfer resistances, rate transfer coefficients and sensitivity towards redox probes the optimal length of acid functionalization for multiwalled carbon nanotubes was 9 hours and 4 hours for single-walled carbon nanotubes. Further improvements in the desired outcomes were achieved through electrochemical activation of the modified electrode surface by cycling in the presence of catechol, in a novel approach. By employing electrochemical impedance spectroscopy it was observed that catechol activation resulted in lowered charge transfer resistance, before and after activation, with functionalized multi-walled carbon nanotubes (9 hours) exhibiting the greatest decrease of 90 % and functionalized single-walled carbon nanotubes (4 hours), a 50 % decrease. Corresponding increases in the heterologous rate transfer coefficient showed a 770 % increase for functionalized multi-walled carbon nanotubes (9 hours), following catechol activation. Comparative observations for fullerenes following partial reduction in potassium hydroxide yielded a 30 % decrease in charge transfer resistance, with an increased heterologous rate transfer coefficient at a fullerene modified surface The performance of the nanomaterial modified electrodes was applied to the detection of wortmannin with applications in bioprocess control and in the pharmaceutical sector as well as to the detection and monitoring of the industrial dye Reactive red. Of particular relevance to these analytes was the assessment of the nanomaterial modified electrodes for enhanced stability, reproducibility, sensitivity and decreased passivation effects. In this study the first known account of wortmannin detection through electrochemical methods is reported. Voltammetric characterization of wortmannin revealed an irreversible cathodic process with a total number of 4 electrons and a diffusion coefficient of 1.19 x 10-7 cm².s⁻¹. At a functionalized multiwalled carbon nanotubes modified glassy carbon electrode a limit of detection of 0.128 nmol.cm⁻³ was obtained, and with limited surface passivation the detection scheme afforded pertinent analyses in biological media representing a substantial improvement over chromatographic detection methods. This study also provided the first account of the voltammetric detection of reactive red, competing favourably with traditional spectroscopic methods for monitoring biodegradation of this compound in real time.
- Full Text:
- Date Issued: 2011
- Authors: Brimecombe, Rory Dennis
- Date: 2011
- Subjects: Voltammetry , Electrochemistry , Nanotubes , Nanostructured materials
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4101 , http://hdl.handle.net/10962/d1009721
- Description: Nanomaterials, in particular carbon nanotubes have been shown to exhibit favourable properties for the enhancement of electrochemical detection of target analytes in complex matrices. There is however scope for improvement in terms of the optimization thereof in electrochemical sensors surface modification. The aim of this thesis was to examine methods that would result in increased current response, lowered passivation and application of such modified surfaces with application to pharmaceutically and industrially relevant analytes. Current methods for enhancing the performance of carbon nanotubes include acid functionalization which not only increases the hydrophilicity of the nanotubes, and consequently their ability to provide stable (aqueous) suspensions, but also introduces electrochemically active sites. This particular approach is however not normalized in the literature. Over-exposure to acid treatment results in loss of structural integrity of the carbon nanotubes, and as such a fine balance exists between achieving these dual outcomes. Guided by high resolution scanning electron microscopy, atomic force microscopy, voltammetric and impedance studies, this thesis examined the role of the length of time of the acid functionalization process as well as the impact of activation of carbon nanotubes and fullerenes on electrochemical sensor performance. Based on desired charge transfer resistances, rate transfer coefficients and sensitivity towards redox probes the optimal length of acid functionalization for multiwalled carbon nanotubes was 9 hours and 4 hours for single-walled carbon nanotubes. Further improvements in the desired outcomes were achieved through electrochemical activation of the modified electrode surface by cycling in the presence of catechol, in a novel approach. By employing electrochemical impedance spectroscopy it was observed that catechol activation resulted in lowered charge transfer resistance, before and after activation, with functionalized multi-walled carbon nanotubes (9 hours) exhibiting the greatest decrease of 90 % and functionalized single-walled carbon nanotubes (4 hours), a 50 % decrease. Corresponding increases in the heterologous rate transfer coefficient showed a 770 % increase for functionalized multi-walled carbon nanotubes (9 hours), following catechol activation. Comparative observations for fullerenes following partial reduction in potassium hydroxide yielded a 30 % decrease in charge transfer resistance, with an increased heterologous rate transfer coefficient at a fullerene modified surface The performance of the nanomaterial modified electrodes was applied to the detection of wortmannin with applications in bioprocess control and in the pharmaceutical sector as well as to the detection and monitoring of the industrial dye Reactive red. Of particular relevance to these analytes was the assessment of the nanomaterial modified electrodes for enhanced stability, reproducibility, sensitivity and decreased passivation effects. In this study the first known account of wortmannin detection through electrochemical methods is reported. Voltammetric characterization of wortmannin revealed an irreversible cathodic process with a total number of 4 electrons and a diffusion coefficient of 1.19 x 10-7 cm².s⁻¹. At a functionalized multiwalled carbon nanotubes modified glassy carbon electrode a limit of detection of 0.128 nmol.cm⁻³ was obtained, and with limited surface passivation the detection scheme afforded pertinent analyses in biological media representing a substantial improvement over chromatographic detection methods. This study also provided the first account of the voltammetric detection of reactive red, competing favourably with traditional spectroscopic methods for monitoring biodegradation of this compound in real time.
- Full Text:
- Date Issued: 2011
Nanostructures and metallophthalocyanines : applications in microbial fuel cells
- Authors: Edwards, Sean
- Date: 2011
- Subjects: Microbial fuel cells , Waste products as fuel , Nanostructured materials , Electrochemistry , Nanotubes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4107 , http://hdl.handle.net/10962/d1011742 , Microbial fuel cells , Waste products as fuel , Nanostructured materials , Electrochemistry , Nanotubes
- Description: Microbial fuel cells (MFCs) are a promising form of alternative energy capable of harnessing the potential energy stores in organic waste. The oxygen reduction reaction (ORR) forms an integral role in the generation of electricity in MFCs however it is also a potential obstacle in enhancing the performance of MFCs. Platinum, a commonly used catalyst for the ORR, is expensive and rare. Significant research has been conducted into developing alternative catalysts. Metallophthalocyanines (MPc) have garnered attention for use as catalysts. Iron phthalocyanine (FePc) has been shown to have catalytic activity towards the reduction of oxygen. Coupling of the catalyst to nanostructured carbon materials, such as multi-walled carbon nanotubes, has been observed to have several advantages as nanostructures have a high surface-to-volume ratio. In this study, we have attempted to assess the suitability of FePc, both its bulk and nanostructured form, as an oxygen reduction catalyst and acid functionalized multi-walled carbon nanotubes for use as a catalyst support using electrochemical techniques such as cyclic voltammetry and electrochemical impedance spectroscopy. We showed, for the first time, the catalytic nature of nanostructured FePc towards the ORR. Applying the data obtained from the electrochemical analyses, electrodes were modified using FePc and MWCNTs and applied to an Enterobacter cloacae-based MFC. Several operational parameters of the MFC, such as temperature and ionic strength, were optimized during the course of the study. We showed that optimized FePc:MWCNT-modified electrodes compared favourably to platinum-based electrodes in terms of power densities obtained in a microbial fuel cell.
- Full Text:
- Date Issued: 2011
- Authors: Edwards, Sean
- Date: 2011
- Subjects: Microbial fuel cells , Waste products as fuel , Nanostructured materials , Electrochemistry , Nanotubes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4107 , http://hdl.handle.net/10962/d1011742 , Microbial fuel cells , Waste products as fuel , Nanostructured materials , Electrochemistry , Nanotubes
- Description: Microbial fuel cells (MFCs) are a promising form of alternative energy capable of harnessing the potential energy stores in organic waste. The oxygen reduction reaction (ORR) forms an integral role in the generation of electricity in MFCs however it is also a potential obstacle in enhancing the performance of MFCs. Platinum, a commonly used catalyst for the ORR, is expensive and rare. Significant research has been conducted into developing alternative catalysts. Metallophthalocyanines (MPc) have garnered attention for use as catalysts. Iron phthalocyanine (FePc) has been shown to have catalytic activity towards the reduction of oxygen. Coupling of the catalyst to nanostructured carbon materials, such as multi-walled carbon nanotubes, has been observed to have several advantages as nanostructures have a high surface-to-volume ratio. In this study, we have attempted to assess the suitability of FePc, both its bulk and nanostructured form, as an oxygen reduction catalyst and acid functionalized multi-walled carbon nanotubes for use as a catalyst support using electrochemical techniques such as cyclic voltammetry and electrochemical impedance spectroscopy. We showed, for the first time, the catalytic nature of nanostructured FePc towards the ORR. Applying the data obtained from the electrochemical analyses, electrodes were modified using FePc and MWCNTs and applied to an Enterobacter cloacae-based MFC. Several operational parameters of the MFC, such as temperature and ionic strength, were optimized during the course of the study. We showed that optimized FePc:MWCNT-modified electrodes compared favourably to platinum-based electrodes in terms of power densities obtained in a microbial fuel cell.
- Full Text:
- Date Issued: 2011
Narratives of curriculum adaptations: teacher challenges in the face of curriculum reform
- Authors: Harricharan, Romila
- Date: 2011
- Subjects: Curriculum change , Basic education , Education -- South Africa , Education -- Curricula , Education and state
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9449 , http://hdl.handle.net/10948/d1008618 , Curriculum change , Basic education , Education -- South Africa , Education -- Curricula , Education and state
- Description: Prior to the landmark 1994 democratic elections the South African education system was unequal and departmentalised. The transformation in South African politics was reflected in the changes implemented in the education curriculum. A massive shift in the basic education process was put into operation, in an attempt to create an amalgamated system which would equally benefit all learners (Hackenberg, 2002:20). These curriculum alterations created a lot of dissatisfaction and a sense of frustration among the teaching fraternity (Maphalala, 2006:7 and Knight, 2005:27). The basis of this study focuses on my concern that teachers, already tense and overworked, face many challenges when curriculum modifications occur, and may find it extremely difficult to cope with them. The associated challenges may lead to excess stress, adversity and teachers becoming ill. For this research study I evaluated how teachers confront and cope with the challenges associated with changes to curriculum. The method and success of these coping skills and the management of curriculum revision is directly linked to certain issues, which may exacerbate problems stemming from these changes and have negative effects of on the teachers themselves. This study is a narrative of teachers’ experiences and was primarily conducted in the Umlazi Circuit of the KwaZulu Natal Department of Education. Purposive sampling was utilised by me, whereby the respondents, teachers who had over twenty years of teaching experience, were carefully selected from four primary schools and one secondary school. The study used the qualitative research approach within the interpretive paradigm, allowing for an in-depth insight into the challenges faced by teachers with changes to the curriculum. Data was collected through semi-structured interviews and observation. The data was later analysed using codes, themes and categories. This analysis revealed that curriculum changes cause teachers to experience many challenges in the classroom. These challenges include, amongst others, lack of resources; discipline problems; excessive workloads; overcrowded classrooms; and insufficient professional development workshops.
- Full Text:
- Date Issued: 2011
- Authors: Harricharan, Romila
- Date: 2011
- Subjects: Curriculum change , Basic education , Education -- South Africa , Education -- Curricula , Education and state
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9449 , http://hdl.handle.net/10948/d1008618 , Curriculum change , Basic education , Education -- South Africa , Education -- Curricula , Education and state
- Description: Prior to the landmark 1994 democratic elections the South African education system was unequal and departmentalised. The transformation in South African politics was reflected in the changes implemented in the education curriculum. A massive shift in the basic education process was put into operation, in an attempt to create an amalgamated system which would equally benefit all learners (Hackenberg, 2002:20). These curriculum alterations created a lot of dissatisfaction and a sense of frustration among the teaching fraternity (Maphalala, 2006:7 and Knight, 2005:27). The basis of this study focuses on my concern that teachers, already tense and overworked, face many challenges when curriculum modifications occur, and may find it extremely difficult to cope with them. The associated challenges may lead to excess stress, adversity and teachers becoming ill. For this research study I evaluated how teachers confront and cope with the challenges associated with changes to curriculum. The method and success of these coping skills and the management of curriculum revision is directly linked to certain issues, which may exacerbate problems stemming from these changes and have negative effects of on the teachers themselves. This study is a narrative of teachers’ experiences and was primarily conducted in the Umlazi Circuit of the KwaZulu Natal Department of Education. Purposive sampling was utilised by me, whereby the respondents, teachers who had over twenty years of teaching experience, were carefully selected from four primary schools and one secondary school. The study used the qualitative research approach within the interpretive paradigm, allowing for an in-depth insight into the challenges faced by teachers with changes to the curriculum. Data was collected through semi-structured interviews and observation. The data was later analysed using codes, themes and categories. This analysis revealed that curriculum changes cause teachers to experience many challenges in the classroom. These challenges include, amongst others, lack of resources; discipline problems; excessive workloads; overcrowded classrooms; and insufficient professional development workshops.
- Full Text:
- Date Issued: 2011
National case study : teacher professional development with an education for sustainable development focus in South Africa: development of a network, curriculum framework and resources for teacher education
- Authors: Lotz-Sisitka, Heila
- Date: 2011
- Subjects: Teachers -- Training of , Career development , Sustainable development -- South Africa
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59646 , vital:27634 , https://www.ajol.info/index.php/sajee/article/view/122242
- Description: This national case study reports on the development of a national network, curriculum framework and resources for teacher education, with specific focus on the inclusion of environment and sustainability, also known as education for sustainable development (ESD) in the South African teacher education system. It reviews and reports on the history of environment and sustainability education in teacher education, and from this, the national case study begins to conceptualise a new approach to environment and sustainability teacher education within a new curriculum policy environment, and a new teacher education and development policy environment. Action research case study methodology is used to document the first phase of the emergence of this network, and this report covers Phase 1 of the initiative, which covers formation of the network, review of previous practices, three conceptual development pilot studies undertaken in both in-service and pre-service teacher education environments and a piloting of a ‘Train the Trainers’ or ‘Educate the Teacher Educators’ programme, which complements and extends the actual teacher education and development (TED) programme under development. The study highlights critical insights of relevance to the shift to a content referenced curriculum in South Africa, and shows how the ‘knowledge mix’ which forms the foundation of the new Teacher Education Qualifications Framework can be engaged. It also highlights some features of the changing knowledge environment, and what dominant knowledge practices are in environment and sustainability-related teaching and teacher education practices, opening these up for further scrutiny. It raises concerns that dominant knowledge work, while integrating a range of forms of knowledge (as is expected of the teacher education system under the new policy), tends to be limited by content on problems and issues for raising awareness, and fails to develop deeper conceptual depth and understanding of environment and sustainability, as issues based knowledge dominates. Similarly, it fails to support social innovation as a response to environment and sustainability concerns, as awareness raising dominates in dominant knowledge work. The study provides a revised conceptual framework for the Teacher Development Network (TEDN) programme, with guidance on key elements necessary to take the programme forward in Phase 2.
- Full Text:
- Date Issued: 2011
- Authors: Lotz-Sisitka, Heila
- Date: 2011
- Subjects: Teachers -- Training of , Career development , Sustainable development -- South Africa
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59646 , vital:27634 , https://www.ajol.info/index.php/sajee/article/view/122242
- Description: This national case study reports on the development of a national network, curriculum framework and resources for teacher education, with specific focus on the inclusion of environment and sustainability, also known as education for sustainable development (ESD) in the South African teacher education system. It reviews and reports on the history of environment and sustainability education in teacher education, and from this, the national case study begins to conceptualise a new approach to environment and sustainability teacher education within a new curriculum policy environment, and a new teacher education and development policy environment. Action research case study methodology is used to document the first phase of the emergence of this network, and this report covers Phase 1 of the initiative, which covers formation of the network, review of previous practices, three conceptual development pilot studies undertaken in both in-service and pre-service teacher education environments and a piloting of a ‘Train the Trainers’ or ‘Educate the Teacher Educators’ programme, which complements and extends the actual teacher education and development (TED) programme under development. The study highlights critical insights of relevance to the shift to a content referenced curriculum in South Africa, and shows how the ‘knowledge mix’ which forms the foundation of the new Teacher Education Qualifications Framework can be engaged. It also highlights some features of the changing knowledge environment, and what dominant knowledge practices are in environment and sustainability-related teaching and teacher education practices, opening these up for further scrutiny. It raises concerns that dominant knowledge work, while integrating a range of forms of knowledge (as is expected of the teacher education system under the new policy), tends to be limited by content on problems and issues for raising awareness, and fails to develop deeper conceptual depth and understanding of environment and sustainability, as issues based knowledge dominates. Similarly, it fails to support social innovation as a response to environment and sustainability concerns, as awareness raising dominates in dominant knowledge work. The study provides a revised conceptual framework for the Teacher Development Network (TEDN) programme, with guidance on key elements necessary to take the programme forward in Phase 2.
- Full Text:
- Date Issued: 2011
Near Real-time Aggregation and Visualisation of Hostile Network Traffic
- Hunter, Samuel O, Irwin, Barry V W
- Authors: Hunter, Samuel O , Irwin, Barry V W
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428067 , vital:72484 , https://www.researchgate.net/profile/Barry-Irwin/publication/327622653_Near_Real-time_Aggregation_and_Visualisation_of_Hostile_Network_Traffic/links/5b9a1474a6fdcc59bf8dfcc2/Near-Real-time-Aggregation-and-Visualisation-of-Hostile-Network-Traffic.pdf4
- Description: Efficient utilization of hostile network traffic for visualization and defen-sive purposes require near real-time availability of such data. Hostile or malicious traffic was obtained through the use of network telescopes and honeypots, as they are effective at capturing mostly illegitimate and nefarious traffic. The data is then exposed in near real-time through a messaging framework and visualized with the help of a geolocation based visualization tool. Defensive applications with regards to hostile network traffic are explored; these include the dynamic quarantine of malicious hosts internal to a network and the egress filtering of denial of service traffic originating from inside a network.
- Full Text:
- Date Issued: 2011
- Authors: Hunter, Samuel O , Irwin, Barry V W
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428067 , vital:72484 , https://www.researchgate.net/profile/Barry-Irwin/publication/327622653_Near_Real-time_Aggregation_and_Visualisation_of_Hostile_Network_Traffic/links/5b9a1474a6fdcc59bf8dfcc2/Near-Real-time-Aggregation-and-Visualisation-of-Hostile-Network-Traffic.pdf4
- Description: Efficient utilization of hostile network traffic for visualization and defen-sive purposes require near real-time availability of such data. Hostile or malicious traffic was obtained through the use of network telescopes and honeypots, as they are effective at capturing mostly illegitimate and nefarious traffic. The data is then exposed in near real-time through a messaging framework and visualized with the help of a geolocation based visualization tool. Defensive applications with regards to hostile network traffic are explored; these include the dynamic quarantine of malicious hosts internal to a network and the egress filtering of denial of service traffic originating from inside a network.
- Full Text:
- Date Issued: 2011
Nearshore subtidal soft-bottom macrozoobenthic community structure in the western sector of Algoa Bay, South Africa
- Authors: Masikane, Ntuthuko Fortune
- Date: 2011
- Subjects: Benthic animals -- South Africa -- Algoa Bay , Benthos
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10684 , http://hdl.handle.net/10948/1466 , Benthic animals -- South Africa -- Algoa Bay , Benthos
- Description: The objectives of this study were to characterise macrozoobenthic community structure of the western sector of Algoa Bay, to identify the drivers of community structure and to develop a long-term monitoring framework. Data were collected from six study sites stratified along-shore. Each site comprised three stations; most sites were located in areas directly influenced by anthropogenic activities such as inflow from storm water drains and areas where dredged spoil was dumped. Other sites included areas in close proximity to estuary mouths. Physico-chemical parameters of the water column were measured with a YSI instrument, sediment for faunal and physico-chemical analyses was sampled with a Van Veen grab, and collected macrofauna were sedated and preserved pending analysis. In the laboratory, macrofauna were identified to finest taxonomic resolution possible under dissecting and compound microscopes, and enumerated. Sediment samples for physico-chemical analyses were kept frozen pending analysis. Up to 187 species belonging to 137 genera and 105 families were identified. Univariate community parameters such as abundance and number of species varied significantly along-shore, generally increasing towards less wave-exposed sites. Multivariate analyses revealed that community assemblages were heterogeneously distributed along-shore, corresponding to areas where anthropogenic influences such as effluent discharge and commercial harbour activities prevailed. During the 2008 survey, species assemblages separated into six groups corresponding to the six sites but xvii during the 2009 survey, species assemblages separated into four groups probably due to changes in environmental parameters such as the hydrodynamic regime. In both surveys the assemblage opposite a drainage canal (Papenkuils outfall) was distinct as it was dissimilar to all other assemblages. This site was also heterogeneous over relatively small spatial scales. Important physico-chemical variables influencing community structures during the 2008 survey included bottom measurements of temperature, salinity, dissolved oxygen, coarse sand and mud. During the 2009 survey, only bottom temperature and mud content were identified as important physico-chemical variables structuring community assemblages. The principal variable was probably the hydrodynamic regime, driving community structure at a larger scale in Algoa Bay. On a localised scale, communities were probably structured by other factors such as effluent discharges, influence of estuary mouths and activities associated with the harbour. With a lack of information on keystone species (regarded as good monitoring species) in Algoa Bay, it was proposed that groups that cumulatively comprise 50–75 percent of total abundance within communities be monitored annually. Included are amphipods, polychaetes, cumaceans, ostracods, tanaids and bivalves. It was also proposed that areas opposite estuary mouths, effluent outfalls and the dredged spoil dumpsite be monitored. This routine monitoring programme should be accompanied by periodic hypothesis driven research to assess the importance of stochastic events (e.g., upwelling) on macrozoobenthic community dynamics. Keywords: macrozoobenthos, soft-bottom, community assemblages, spatial distribution patterns, environmental drivers, long-term monitoring framework.
- Full Text:
- Date Issued: 2011
- Authors: Masikane, Ntuthuko Fortune
- Date: 2011
- Subjects: Benthic animals -- South Africa -- Algoa Bay , Benthos
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10684 , http://hdl.handle.net/10948/1466 , Benthic animals -- South Africa -- Algoa Bay , Benthos
- Description: The objectives of this study were to characterise macrozoobenthic community structure of the western sector of Algoa Bay, to identify the drivers of community structure and to develop a long-term monitoring framework. Data were collected from six study sites stratified along-shore. Each site comprised three stations; most sites were located in areas directly influenced by anthropogenic activities such as inflow from storm water drains and areas where dredged spoil was dumped. Other sites included areas in close proximity to estuary mouths. Physico-chemical parameters of the water column were measured with a YSI instrument, sediment for faunal and physico-chemical analyses was sampled with a Van Veen grab, and collected macrofauna were sedated and preserved pending analysis. In the laboratory, macrofauna were identified to finest taxonomic resolution possible under dissecting and compound microscopes, and enumerated. Sediment samples for physico-chemical analyses were kept frozen pending analysis. Up to 187 species belonging to 137 genera and 105 families were identified. Univariate community parameters such as abundance and number of species varied significantly along-shore, generally increasing towards less wave-exposed sites. Multivariate analyses revealed that community assemblages were heterogeneously distributed along-shore, corresponding to areas where anthropogenic influences such as effluent discharge and commercial harbour activities prevailed. During the 2008 survey, species assemblages separated into six groups corresponding to the six sites but xvii during the 2009 survey, species assemblages separated into four groups probably due to changes in environmental parameters such as the hydrodynamic regime. In both surveys the assemblage opposite a drainage canal (Papenkuils outfall) was distinct as it was dissimilar to all other assemblages. This site was also heterogeneous over relatively small spatial scales. Important physico-chemical variables influencing community structures during the 2008 survey included bottom measurements of temperature, salinity, dissolved oxygen, coarse sand and mud. During the 2009 survey, only bottom temperature and mud content were identified as important physico-chemical variables structuring community assemblages. The principal variable was probably the hydrodynamic regime, driving community structure at a larger scale in Algoa Bay. On a localised scale, communities were probably structured by other factors such as effluent discharges, influence of estuary mouths and activities associated with the harbour. With a lack of information on keystone species (regarded as good monitoring species) in Algoa Bay, it was proposed that groups that cumulatively comprise 50–75 percent of total abundance within communities be monitored annually. Included are amphipods, polychaetes, cumaceans, ostracods, tanaids and bivalves. It was also proposed that areas opposite estuary mouths, effluent outfalls and the dredged spoil dumpsite be monitored. This routine monitoring programme should be accompanied by periodic hypothesis driven research to assess the importance of stochastic events (e.g., upwelling) on macrozoobenthic community dynamics. Keywords: macrozoobenthos, soft-bottom, community assemblages, spatial distribution patterns, environmental drivers, long-term monitoring framework.
- Full Text:
- Date Issued: 2011
Negotiating the global : how young women in Nairobi shape their local identities in response to aspects of the mexican telenovela, Cuando seas mia
- Authors: Jiwaji, Aamera Hamzaali
- Date: 2011 , 2010-09-15
- Subjects: Cuando seas mia (Television program) , Television soap operas -- Kenya , Motion pictures and youth -- Kenya , Emigration and immigration in motion pictures -- Kenya , Ethnicity in motion pictures -- Kenya , Arts and society -- Kenya
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3532 , http://hdl.handle.net/10962/d1013364
- Description: Latin American telenovelas have been exported to more than a hundred countries across the globe. While they are popular in their country of production because their messages resonate with their audience’s everyday experiences, their popularity amongst global audiences with whom they share neither a social nor a cultural history is unexplained. Kenya has been importing and airing Latin American telenovelas since the early 1990s, and telenovelas have permeated many aspects of Kenyan daily life, when compared to other foreign globally-distributed media products that are aired on Kenyan television. As global media products, telenovelas remain open to criticisms from the media imperialism thesis. This research adopts an ethnographic approach to the study of audiences, and looks at the reception of a Mexican telenovela, Cuando Seas Mia, by a group of young Kenyan women in Nairobi. It reflects upon the media imperialism thesis from an African perspective by investigating the meanings that these women make from Cuando Seas Mia, and how these shape their changing local identities and cultures. The young women in this study, most of whom have moved to the city from the rural areas, are influenced by traditional, patriarchal Kenyan society and by the modern, Western influences of an urban environment. They experience a tension between their evolving rural and urban roles and identities and are drawn to telenovelas because their exploration of rural-urban themes holds a relevance to their own lives. They negotiate their contemporary African youth identities, gender roles and heterosexual relationships in relation to representations in the telenovela, questioning and destabilising African and Western definitions. These women select aspects from their traditional, African cultures and from their modern, Western experiences (and consumption of global media) and reconstruct them into a transitional youth identity which suits their day to day lives as young women living in an urban African environment.
- Full Text:
- Date Issued: 2011
- Authors: Jiwaji, Aamera Hamzaali
- Date: 2011 , 2010-09-15
- Subjects: Cuando seas mia (Television program) , Television soap operas -- Kenya , Motion pictures and youth -- Kenya , Emigration and immigration in motion pictures -- Kenya , Ethnicity in motion pictures -- Kenya , Arts and society -- Kenya
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3532 , http://hdl.handle.net/10962/d1013364
- Description: Latin American telenovelas have been exported to more than a hundred countries across the globe. While they are popular in their country of production because their messages resonate with their audience’s everyday experiences, their popularity amongst global audiences with whom they share neither a social nor a cultural history is unexplained. Kenya has been importing and airing Latin American telenovelas since the early 1990s, and telenovelas have permeated many aspects of Kenyan daily life, when compared to other foreign globally-distributed media products that are aired on Kenyan television. As global media products, telenovelas remain open to criticisms from the media imperialism thesis. This research adopts an ethnographic approach to the study of audiences, and looks at the reception of a Mexican telenovela, Cuando Seas Mia, by a group of young Kenyan women in Nairobi. It reflects upon the media imperialism thesis from an African perspective by investigating the meanings that these women make from Cuando Seas Mia, and how these shape their changing local identities and cultures. The young women in this study, most of whom have moved to the city from the rural areas, are influenced by traditional, patriarchal Kenyan society and by the modern, Western influences of an urban environment. They experience a tension between their evolving rural and urban roles and identities and are drawn to telenovelas because their exploration of rural-urban themes holds a relevance to their own lives. They negotiate their contemporary African youth identities, gender roles and heterosexual relationships in relation to representations in the telenovela, questioning and destabilising African and Western definitions. These women select aspects from their traditional, African cultures and from their modern, Western experiences (and consumption of global media) and reconstruct them into a transitional youth identity which suits their day to day lives as young women living in an urban African environment.
- Full Text:
- Date Issued: 2011
Nelson Mandela Metropolitan University students' perceptions of sexualised advertisements of three South African fast food brands
- Authors: Wignall, Andrea
- Date: 2011
- Subjects: Sex in advertising -- South Africa -- Childhood and youth , Food industry and trade -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8408 , http://hdl.handle.net/10948/d1011443 , Sex in advertising -- South Africa -- Childhood and youth , Food industry and trade -- South Africa
- Description: This research study aimed to provide the South African fast food industry and their advertising representatives with insights into 18-28-year-olds‟ perception of using sexual appeal to elicit their attention, and whether using this advertising technique is gaining positive brand recognition with this target market. This research study aimed to determine the selected sample‟s (NMMU students) perceptions of three South African fast food brands, namely KFC, Nando’s and Steers, in terms of their use of sexualised fast food advertisements. An electronic survey questionnaire was conducted with both closed and open-ended questions relating to the use of sexual appeal in advertising within the three South African fast food brands. The survey questionnaire helped determine what the selected sample‟s perceptions were of each advertisement, and whether the use of sexual appeal captured their attention. A semiotic analysis of each advertisement was conducted to determine if the advertisements do contain the use of sexual appeal, by examining the sign. This includes looking at the three aspects of a sign namely the signifier, the referent and the signified. In terms of this study, the signifier represents the T.V. advertisements; the signified represents the meaning of the advertisements and the referent represents to what the advertisements are initially referring. The results of the study indicated that each of the three fast food advertisements incorporated the use of sexual appeal in varying degrees. Respondents indicated that the sexual appeal in the advertisements was appropriate if they were directed at the right age group. The respondents indicated that these three advertisements were more likely to attract the males, in the target market and they felt that the advertisements leaned towards objectifying the women, which would be offensive to the females in the target market. It was determined that if the advertisements contained humour, they were more effective and memorable.
- Full Text:
- Date Issued: 2011
- Authors: Wignall, Andrea
- Date: 2011
- Subjects: Sex in advertising -- South Africa -- Childhood and youth , Food industry and trade -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8408 , http://hdl.handle.net/10948/d1011443 , Sex in advertising -- South Africa -- Childhood and youth , Food industry and trade -- South Africa
- Description: This research study aimed to provide the South African fast food industry and their advertising representatives with insights into 18-28-year-olds‟ perception of using sexual appeal to elicit their attention, and whether using this advertising technique is gaining positive brand recognition with this target market. This research study aimed to determine the selected sample‟s (NMMU students) perceptions of three South African fast food brands, namely KFC, Nando’s and Steers, in terms of their use of sexualised fast food advertisements. An electronic survey questionnaire was conducted with both closed and open-ended questions relating to the use of sexual appeal in advertising within the three South African fast food brands. The survey questionnaire helped determine what the selected sample‟s perceptions were of each advertisement, and whether the use of sexual appeal captured their attention. A semiotic analysis of each advertisement was conducted to determine if the advertisements do contain the use of sexual appeal, by examining the sign. This includes looking at the three aspects of a sign namely the signifier, the referent and the signified. In terms of this study, the signifier represents the T.V. advertisements; the signified represents the meaning of the advertisements and the referent represents to what the advertisements are initially referring. The results of the study indicated that each of the three fast food advertisements incorporated the use of sexual appeal in varying degrees. Respondents indicated that the sexual appeal in the advertisements was appropriate if they were directed at the right age group. The respondents indicated that these three advertisements were more likely to attract the males, in the target market and they felt that the advertisements leaned towards objectifying the women, which would be offensive to the females in the target market. It was determined that if the advertisements contained humour, they were more effective and memorable.
- Full Text:
- Date Issued: 2011
Neogene fluvial deposits along the south-west coast of South Africa understanding the palaeoclimate through proxies
- Authors: Sciscio, Lara
- Date: 2011
- Subjects: Alluvium , Paleoclimatology -- South Africa , Paleoecology -- Miocene -- South Africa , Paleobotany -- Miocene -- South Africa , Paleogeography -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4981 , http://hdl.handle.net/10962/d1005593 , Alluvium , Paleoclimatology -- South Africa , Paleoecology -- Miocene -- South Africa , Paleobotany -- Miocene -- South Africa , Paleogeography -- South Africa
- Description: Branched glycerol dialkyl glycerol tetraether (GDGTs) membrane lipids have been used as a new proxy for the reconstruction of terrestrial palaeoclimates. These biomarkers (or molecular ‗fossils‘) in conjunction with palynology, have been effective in the novel analysis of Miocene organic-rich sediments from three South African west coast sites at Rondeberg, Noordhoek and Langebaanweg. Lastly, a Quaternary south coast site at Rietvlei, South Africa, was also studied to further elucidate the extent of use of this new proxy. The fluvial peat and organic-rich deposits of the Elandsfontyn Formation (Sandveld Group) were investigated at Noordhoek, Langebaanweg and Rondeberg to provide new evidence for the climate and vegetation patterns during Miocene in this region. Drill-core and quarry samples from all four sites were freeze-dried, powered, and prepared for biogeochemical and palynological analyses. The methylation index of branched tetraethers (MBT) and cyclisation ratio of branched tetraethers (CBT) proxies were used to calculate the mean annual air temperature (MAAT) and pH values of the organic-rich horizons at time of deposition. The Branched versus isoprenoid index of tetraethers (BIT) was used to assess the relative contributions of marine archaeal and terrestrial bacterial tetraethers, and thereby assess the validity of the MBT, CBT and calculated palaeoenvironmental factors. The results presented in this thesis suggest that the use of the MBT/CBT proxy has significant potential in southern Africa, and may complement previously attempted palaeoclimatic and palaeoecological studies of Neogene-aged South African sediments. This type of research has the capacity to provide palaeoenvironmental information where other proxies may be absent. Results indicate that all sites yielded branched tetraether membrane lipids with the exception of Rondeberg, where GDGTs were below detection as a result of poor preservation conditions. Palynological investigation confirmed proxy derived temperatures. Furthermore palynomorph analyses supplemented earlier studies of the Noordhoek site and were piloted for the Rondeberg site, reaffirming alternating sequences of tropical and subtropical palynofloras. The MAATs, likewise, show variability and pronounced trends through time at the Langebaanweg and Noordhoek sites, generally corresponding with the variation and diversity of the pollen population. The terrestrial MAAT results appear to compliment Southern Hemisphere sea level changes associated with Antarctic glaciations. Additionally, this data shows a pattern similar to the Southern and Northern Hemisphere marine isotope records of relative fluctuations in the global climate and sea level change from the early to middle Miocene. The application of these past climate change indicators have been proved to be useful in the reconstruction of South Africa Miocene palaeoclimates, and may aid in understanding the consequences of climate change in the Cape region.
- Full Text:
- Date Issued: 2011
- Authors: Sciscio, Lara
- Date: 2011
- Subjects: Alluvium , Paleoclimatology -- South Africa , Paleoecology -- Miocene -- South Africa , Paleobotany -- Miocene -- South Africa , Paleogeography -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4981 , http://hdl.handle.net/10962/d1005593 , Alluvium , Paleoclimatology -- South Africa , Paleoecology -- Miocene -- South Africa , Paleobotany -- Miocene -- South Africa , Paleogeography -- South Africa
- Description: Branched glycerol dialkyl glycerol tetraether (GDGTs) membrane lipids have been used as a new proxy for the reconstruction of terrestrial palaeoclimates. These biomarkers (or molecular ‗fossils‘) in conjunction with palynology, have been effective in the novel analysis of Miocene organic-rich sediments from three South African west coast sites at Rondeberg, Noordhoek and Langebaanweg. Lastly, a Quaternary south coast site at Rietvlei, South Africa, was also studied to further elucidate the extent of use of this new proxy. The fluvial peat and organic-rich deposits of the Elandsfontyn Formation (Sandveld Group) were investigated at Noordhoek, Langebaanweg and Rondeberg to provide new evidence for the climate and vegetation patterns during Miocene in this region. Drill-core and quarry samples from all four sites were freeze-dried, powered, and prepared for biogeochemical and palynological analyses. The methylation index of branched tetraethers (MBT) and cyclisation ratio of branched tetraethers (CBT) proxies were used to calculate the mean annual air temperature (MAAT) and pH values of the organic-rich horizons at time of deposition. The Branched versus isoprenoid index of tetraethers (BIT) was used to assess the relative contributions of marine archaeal and terrestrial bacterial tetraethers, and thereby assess the validity of the MBT, CBT and calculated palaeoenvironmental factors. The results presented in this thesis suggest that the use of the MBT/CBT proxy has significant potential in southern Africa, and may complement previously attempted palaeoclimatic and palaeoecological studies of Neogene-aged South African sediments. This type of research has the capacity to provide palaeoenvironmental information where other proxies may be absent. Results indicate that all sites yielded branched tetraether membrane lipids with the exception of Rondeberg, where GDGTs were below detection as a result of poor preservation conditions. Palynological investigation confirmed proxy derived temperatures. Furthermore palynomorph analyses supplemented earlier studies of the Noordhoek site and were piloted for the Rondeberg site, reaffirming alternating sequences of tropical and subtropical palynofloras. The MAATs, likewise, show variability and pronounced trends through time at the Langebaanweg and Noordhoek sites, generally corresponding with the variation and diversity of the pollen population. The terrestrial MAAT results appear to compliment Southern Hemisphere sea level changes associated with Antarctic glaciations. Additionally, this data shows a pattern similar to the Southern and Northern Hemisphere marine isotope records of relative fluctuations in the global climate and sea level change from the early to middle Miocene. The application of these past climate change indicators have been proved to be useful in the reconstruction of South Africa Miocene palaeoclimates, and may aid in understanding the consequences of climate change in the Cape region.
- Full Text:
- Date Issued: 2011
Network neutral control over quality of service networks
- Foulkes, Phillip, Foss, Richard, Gurdan, Robby
- Authors: Foulkes, Phillip , Foss, Richard , Gurdan, Robby
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427166 , vital:72419 , https://www.aes.org/e-lib/online/browse.cfm?elib=16151
- Description: Creating interoperability between two standards-based network technologies, IEEE 1394 Firewire and Ethernet Audio/Video Bridging (AVB), allows them to exist simultaneously in a single application configuration. While both technologies provide the transport of synchronized, low-latency, real-time audio and video data, they have different approaches to enabling this transport. By using a compatible audio gateway with a common control protocol, audio devices on these disparate networks can be connected and controlled.
- Full Text:
- Date Issued: 2011
- Authors: Foulkes, Phillip , Foss, Richard , Gurdan, Robby
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427166 , vital:72419 , https://www.aes.org/e-lib/online/browse.cfm?elib=16151
- Description: Creating interoperability between two standards-based network technologies, IEEE 1394 Firewire and Ethernet Audio/Video Bridging (AVB), allows them to exist simultaneously in a single application configuration. While both technologies provide the transport of synchronized, low-latency, real-time audio and video data, they have different approaches to enabling this transport. By using a compatible audio gateway with a common control protocol, audio devices on these disparate networks can be connected and controlled.
- Full Text:
- Date Issued: 2011
Neuronal nitric oxide synthase : a biomarker for Alzheimers disease : interaction of neuronal nitric oxide synthase with beta-amyloid peptides in the brain
- Authors: Padayachee, Eden Rebecca
- Date: 2011 , 2013-07-19
- Subjects: Alzheimer's disease , Nitric-oxide synthase , Biochemical markers , Amyloid beta-protein , Peptide hormones
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4086 , http://hdl.handle.net/10962/d1007677 , Alzheimer's disease , Nitric-oxide synthase , Biochemical markers , Amyloid beta-protein , Peptide hormones
- Description: High levels of the amino acid arginine and low levels of the product citrulline in the cerebrospinal fluid of Alzheimer's patients could mean that there is a decrease in the enzymes that metabolize this amino acid. One such enzyme is neuronal nitric oxide synthase (nNOS). In this study, neuronal nitric oxide synthase (nNOS), sourced from bovine brain was extracted and concentrated using two methods of precipitation: poly (ethylene glycol) 20 000 (PEG) and ammonium sulphate [(NH₄)₂S0₄). These two techniques gave no increase in yield nor fold purification and hence were abandoned in favour of ion exchange chromatography by DEAE-Sepharose. The enzyme was then successfully purified by anion-exchange and after dialysis produced a 38% yield and three fold purification and yielded the highest specific activity of 2.27 U/mg. Neuronal nitric oxide synthase (nNOS) was a heterodimeric protein with a total molecular mass of ± 225 kDa (95 and 130 kDa monomers). The temperature and pH optima of the enzyme were 40⁰C and 6.5, respectively. The kinetic parameters (KM and Vmax) of nNOS were 70 μM and 0.332 μmol.min⁻¹, respectively. Moreover neuronal nitric oxide synthase (nNOS) was relatively stable at 40⁰C (t½ = 3 h). It was also confirmed that β-amyloid peptides inhibited nNOS when bound to the enzyme and that nNOS behaved as a catalyst in fibril formation through association-dissociation between enzyme and β-amyloid peptide. It was further shown that Aβ₁₇₋₂₈ inhibited nNOS the most with a Ki of 1.92 μM and also had the highest Stern-Volmer value (Ksv) of 0.11 μM⁻¹ indicating tight binding affinity to nNOS and easier accessibility to fluor molecules during binding. Congo red, turbidity, thioflavin-T assays and transmission electron microscopy were successfully used to detect and visualize the presence of fibrils by studying the process of fibrillogenesis. Computerized molecular modeling successfully studied protein dynamics and conformational changes of nNOS. These results correlated with resonance energy transfer (FRET) results which revealed the distance of tryptophan residues from the arginine bound at enzyme active site. Both the aforementioned techniques revealed that in the natural state of the enzyme with arginine bound at the active site, the tryptophan residues (TRP₆₂₅ and TRP₇₂₁) were positioned at the surface of the enzyme 28 Å away from the active site. When the amyloid peptide (Aβ₁₇₋₂₈) was bound to the active site, these same two amino acids moved 14 Å closer to the active site. A five residue hydrophobic fragment Aβ₁₇₋₂₁ [Leu₁₇ - Val₁₈ - Phe₁₉ - Phe₂₀ - Ala₁] within Aβ₁₇₋₂₈ was shown by computer modeling to be critical to the binding of the peptide to the active site of nNOS.
- Full Text:
- Date Issued: 2011
- Authors: Padayachee, Eden Rebecca
- Date: 2011 , 2013-07-19
- Subjects: Alzheimer's disease , Nitric-oxide synthase , Biochemical markers , Amyloid beta-protein , Peptide hormones
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4086 , http://hdl.handle.net/10962/d1007677 , Alzheimer's disease , Nitric-oxide synthase , Biochemical markers , Amyloid beta-protein , Peptide hormones
- Description: High levels of the amino acid arginine and low levels of the product citrulline in the cerebrospinal fluid of Alzheimer's patients could mean that there is a decrease in the enzymes that metabolize this amino acid. One such enzyme is neuronal nitric oxide synthase (nNOS). In this study, neuronal nitric oxide synthase (nNOS), sourced from bovine brain was extracted and concentrated using two methods of precipitation: poly (ethylene glycol) 20 000 (PEG) and ammonium sulphate [(NH₄)₂S0₄). These two techniques gave no increase in yield nor fold purification and hence were abandoned in favour of ion exchange chromatography by DEAE-Sepharose. The enzyme was then successfully purified by anion-exchange and after dialysis produced a 38% yield and three fold purification and yielded the highest specific activity of 2.27 U/mg. Neuronal nitric oxide synthase (nNOS) was a heterodimeric protein with a total molecular mass of ± 225 kDa (95 and 130 kDa monomers). The temperature and pH optima of the enzyme were 40⁰C and 6.5, respectively. The kinetic parameters (KM and Vmax) of nNOS were 70 μM and 0.332 μmol.min⁻¹, respectively. Moreover neuronal nitric oxide synthase (nNOS) was relatively stable at 40⁰C (t½ = 3 h). It was also confirmed that β-amyloid peptides inhibited nNOS when bound to the enzyme and that nNOS behaved as a catalyst in fibril formation through association-dissociation between enzyme and β-amyloid peptide. It was further shown that Aβ₁₇₋₂₈ inhibited nNOS the most with a Ki of 1.92 μM and also had the highest Stern-Volmer value (Ksv) of 0.11 μM⁻¹ indicating tight binding affinity to nNOS and easier accessibility to fluor molecules during binding. Congo red, turbidity, thioflavin-T assays and transmission electron microscopy were successfully used to detect and visualize the presence of fibrils by studying the process of fibrillogenesis. Computerized molecular modeling successfully studied protein dynamics and conformational changes of nNOS. These results correlated with resonance energy transfer (FRET) results which revealed the distance of tryptophan residues from the arginine bound at enzyme active site. Both the aforementioned techniques revealed that in the natural state of the enzyme with arginine bound at the active site, the tryptophan residues (TRP₆₂₅ and TRP₇₂₁) were positioned at the surface of the enzyme 28 Å away from the active site. When the amyloid peptide (Aβ₁₇₋₂₈) was bound to the active site, these same two amino acids moved 14 Å closer to the active site. A five residue hydrophobic fragment Aβ₁₇₋₂₁ [Leu₁₇ - Val₁₈ - Phe₁₉ - Phe₂₀ - Ala₁] within Aβ₁₇₋₂₈ was shown by computer modeling to be critical to the binding of the peptide to the active site of nNOS.
- Full Text:
- Date Issued: 2011