Characterization of the Hsp40 partner proteins of Plasmodium falciparum Hsp70
- Authors: Njunge, James Mwangi
- Date: 2014
- Subjects: Plasmodium falciparum , Heat shock proteins , Malaria -- Chemotherapy , Protein-protein interactions , Erythrocytes -- Biotechnology , Molecular chaperones , Host-parasite relationships , Mitochondria
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4117 , http://hdl.handle.net/10962/d1013186
- Description: Human malaria is an economically important disease caused by single-celled parasites of the Plasmodium genus whose biology displays great evolutionary adaptation to both its mammalian host and transmitting vectors. This thesis details the 70 kDa heat shock protein (Hsp70) and J protein chaperone complements in malaria parasites affecting humans, primates and rodents. Heat shock proteins comprise a family of evolutionary conserved and structurally related proteins that play a crucial role in maintaining the structural integrity of proteins during normal and stress conditions. They are considered future therapeutic targets in various cellular systems including Plasmodium falciparum. J proteins (Hsp40) canonically partner with Hsp70s during protein synthesis and folding, trafficking or targeting of proteins for degradation. However, in P. falciparum, these classes of proteins have also been implicated in aiding the active transport of parasite proteins to the erythrocyte cytosol following erythrocyte entry by the parasite. This host-parasite “cross-talk” results in tremendous modifications of the infected erythrocyte, imparting properties that allow it to adhere to the endothelium, preventing splenic clearance. The genome of P. falciparum encodes six Hsp70 homologues and a large number of J proteins that localize to the various intracellular compartments or are exported to the infected erythrocyte cytosol. Understanding the Hsp70-J protein interactions and/or partnerships is an essential step for drug target validation and illumination of parasite biology. A review of these chaperone complements across the Plasmodium species shows that P. falciparum possesses an expanded Hsp70-J protein complement compared to the rodent and primate infecting species. It further highlights how unique the P. falciparum chaperone complement is compared to the other Plasmodium species included in the analysis. In silico analysis showed that the genome of P. falciparum encodes approximately 49 J proteins, 19 of which contain a PEXEL motif that has been implicated in routing proteins to the infected erythrocyte. Most of these PEXEL containing J proteins are unique with no homologues in the human system and are considered as attractive drug targets. Very few of the predicted J proteins in P. falciparum have been experimentally characterized. To this end, cell biological and biochemical approaches were employed to characterize PFB0595w and PFD0462w (Pfj1) J proteins. The uniqueness of Pfj1 and the controversy in literature regarding its localization formed the basis for the experimental work. This is the first study showing that Pfj1 localizes to the mitochondrion in the intraerythrocytic stage of development of P. falciparum and has further proposed PfHsp70-3 as a potential Hsp70 partner. Indeed, attempts to heterologously express and purify Pfj1 for its characterization are described. It is also the first study that details the successful expression and purification of PfHsp70-3. Further, research findings have described for the first time the expression and localization of PFB0595w in the intraerythrocytic stages of P. falciparum development. Based on the cytosolic localization of both PFB0595w and PfHsp70-1, a chaperone – cochaperone partnership was proposed that formed the basis for the in vitro experiments. PFB0595w was shown for the first time to stimulate the ATPase activity of PfHsp70-1 pointing to a functional interaction. Preliminary surface plasmon spectroscopy analysis has revealed a potential interaction between PFB0595w and PfHsp70-1 but highlights the need for further related experiments to support the findings. Gel filtration analysis showed that PFB0595w exists as a dimer thereby confirming in silico predictions. Based on these observations, we conclude that PFB0595w may regulate the chaperone activity of PfHsp70-1 in the cytosol while Pfj1 may play a co-chaperoning role for PfHsp70-3 in the mitochondrion. Overall, this data is expected to increase the knowledge of the Hsp70-J protein partnerships in the erythrocytic stage of P. falciparum development, thereby enhancing the understanding of parasite biology.
- Full Text:
- Date Issued: 2014
- Authors: Njunge, James Mwangi
- Date: 2014
- Subjects: Plasmodium falciparum , Heat shock proteins , Malaria -- Chemotherapy , Protein-protein interactions , Erythrocytes -- Biotechnology , Molecular chaperones , Host-parasite relationships , Mitochondria
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4117 , http://hdl.handle.net/10962/d1013186
- Description: Human malaria is an economically important disease caused by single-celled parasites of the Plasmodium genus whose biology displays great evolutionary adaptation to both its mammalian host and transmitting vectors. This thesis details the 70 kDa heat shock protein (Hsp70) and J protein chaperone complements in malaria parasites affecting humans, primates and rodents. Heat shock proteins comprise a family of evolutionary conserved and structurally related proteins that play a crucial role in maintaining the structural integrity of proteins during normal and stress conditions. They are considered future therapeutic targets in various cellular systems including Plasmodium falciparum. J proteins (Hsp40) canonically partner with Hsp70s during protein synthesis and folding, trafficking or targeting of proteins for degradation. However, in P. falciparum, these classes of proteins have also been implicated in aiding the active transport of parasite proteins to the erythrocyte cytosol following erythrocyte entry by the parasite. This host-parasite “cross-talk” results in tremendous modifications of the infected erythrocyte, imparting properties that allow it to adhere to the endothelium, preventing splenic clearance. The genome of P. falciparum encodes six Hsp70 homologues and a large number of J proteins that localize to the various intracellular compartments or are exported to the infected erythrocyte cytosol. Understanding the Hsp70-J protein interactions and/or partnerships is an essential step for drug target validation and illumination of parasite biology. A review of these chaperone complements across the Plasmodium species shows that P. falciparum possesses an expanded Hsp70-J protein complement compared to the rodent and primate infecting species. It further highlights how unique the P. falciparum chaperone complement is compared to the other Plasmodium species included in the analysis. In silico analysis showed that the genome of P. falciparum encodes approximately 49 J proteins, 19 of which contain a PEXEL motif that has been implicated in routing proteins to the infected erythrocyte. Most of these PEXEL containing J proteins are unique with no homologues in the human system and are considered as attractive drug targets. Very few of the predicted J proteins in P. falciparum have been experimentally characterized. To this end, cell biological and biochemical approaches were employed to characterize PFB0595w and PFD0462w (Pfj1) J proteins. The uniqueness of Pfj1 and the controversy in literature regarding its localization formed the basis for the experimental work. This is the first study showing that Pfj1 localizes to the mitochondrion in the intraerythrocytic stage of development of P. falciparum and has further proposed PfHsp70-3 as a potential Hsp70 partner. Indeed, attempts to heterologously express and purify Pfj1 for its characterization are described. It is also the first study that details the successful expression and purification of PfHsp70-3. Further, research findings have described for the first time the expression and localization of PFB0595w in the intraerythrocytic stages of P. falciparum development. Based on the cytosolic localization of both PFB0595w and PfHsp70-1, a chaperone – cochaperone partnership was proposed that formed the basis for the in vitro experiments. PFB0595w was shown for the first time to stimulate the ATPase activity of PfHsp70-1 pointing to a functional interaction. Preliminary surface plasmon spectroscopy analysis has revealed a potential interaction between PFB0595w and PfHsp70-1 but highlights the need for further related experiments to support the findings. Gel filtration analysis showed that PFB0595w exists as a dimer thereby confirming in silico predictions. Based on these observations, we conclude that PFB0595w may regulate the chaperone activity of PfHsp70-1 in the cytosol while Pfj1 may play a co-chaperoning role for PfHsp70-3 in the mitochondrion. Overall, this data is expected to increase the knowledge of the Hsp70-J protein partnerships in the erythrocytic stage of P. falciparum development, thereby enhancing the understanding of parasite biology.
- Full Text:
- Date Issued: 2014
Child justice: an analysis of the development of child justice reform in Botswana
- Isaacs, Nthabiseng Rosalind Bertha
- Authors: Isaacs, Nthabiseng Rosalind Bertha
- Date: 2014
- Subjects: Juvenile justice, Administration of -- Botswana , Criminals -- Rehabilitation -- Botswana , Children's rights -- Botswana
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10184 , http://hdl.handle.net/10948/d1020094
- Description: This dissertation addresses the developments of child justice in Botswana. The first ever child justice that was established is discussed with the aim to understand the influence it had on Botswana with regard to the nature of the proceedings and the founding principles of child justice and its application in the courts. International Conventions that have a bearing on the rights of children in Botswana, such as the Convention on the Rights of the Child, the United Nations Standard Minimum Rules for the Administration of Juvenile Justice, the United Nations Rules for the Protection of Juveniles Deprived of their Liberty, the United Nations Guidelines for the Prevention of Juvenile Delinquency and the African Charter on the Rights and Welfare of the Child are discussed. The measures that are currently in place for the protection of children who are in conflict with the law are examined with particular emphasis on those children that are arrested and detained. A comparison is drawn between the Children’s Act CAP [28:04] OF 1981, the Children’s Act 8 of 2009 and the South African Child Justice Act 75 of 2008 and the differences between the systems are highlighted. The provisions of the 2009 Act pertaining to children in conflict with the law are discussed in depth and shortfalls of the 2009 Children’s Act are identified. Diversion, as a form of correctional action, is discussed in light of international conventions. The provisions regarding the diversion of child offenders in the Child Justice Act are interrogated. Trial procedures under the 2009 Children’s Act are discussed and compared to those in South Africa including measures in place for the sentencing child offenders in both Botswana and South Africa. After an analysis of the international conventions, legislation and case law, the conclusion is reached that there is a commitment in Botswana towards the protectionand realization of children’s rights especially those who are in conflict with the law. It is recommended in the conclusions that Botswana import some provisions of the Child Justice Act into domestic legislation in order to comprehensively address the plight of children in trouble with the law so as to strive towards maximum compliance with conventions that Botswana has signed.
- Full Text:
- Date Issued: 2014
- Authors: Isaacs, Nthabiseng Rosalind Bertha
- Date: 2014
- Subjects: Juvenile justice, Administration of -- Botswana , Criminals -- Rehabilitation -- Botswana , Children's rights -- Botswana
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10184 , http://hdl.handle.net/10948/d1020094
- Description: This dissertation addresses the developments of child justice in Botswana. The first ever child justice that was established is discussed with the aim to understand the influence it had on Botswana with regard to the nature of the proceedings and the founding principles of child justice and its application in the courts. International Conventions that have a bearing on the rights of children in Botswana, such as the Convention on the Rights of the Child, the United Nations Standard Minimum Rules for the Administration of Juvenile Justice, the United Nations Rules for the Protection of Juveniles Deprived of their Liberty, the United Nations Guidelines for the Prevention of Juvenile Delinquency and the African Charter on the Rights and Welfare of the Child are discussed. The measures that are currently in place for the protection of children who are in conflict with the law are examined with particular emphasis on those children that are arrested and detained. A comparison is drawn between the Children’s Act CAP [28:04] OF 1981, the Children’s Act 8 of 2009 and the South African Child Justice Act 75 of 2008 and the differences between the systems are highlighted. The provisions of the 2009 Act pertaining to children in conflict with the law are discussed in depth and shortfalls of the 2009 Children’s Act are identified. Diversion, as a form of correctional action, is discussed in light of international conventions. The provisions regarding the diversion of child offenders in the Child Justice Act are interrogated. Trial procedures under the 2009 Children’s Act are discussed and compared to those in South Africa including measures in place for the sentencing child offenders in both Botswana and South Africa. After an analysis of the international conventions, legislation and case law, the conclusion is reached that there is a commitment in Botswana towards the protectionand realization of children’s rights especially those who are in conflict with the law. It is recommended in the conclusions that Botswana import some provisions of the Child Justice Act into domestic legislation in order to comprehensively address the plight of children in trouble with the law so as to strive towards maximum compliance with conventions that Botswana has signed.
- Full Text:
- Date Issued: 2014
Chinese tourists' intentions to visit South Africa: an extended model of the theory of planned behaviour
- Authors: Han, Xiliang
- Date: 2014
- Subjects: Market segmentation , Tourists -- Attitudes , Sustainable tourism -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9325 , http://hdl.handle.net/10948/d1020945
- Description: The South African National Department of Tourism has recently initiated the National Tourism Sector Strategy aimed at developing a sustainable tourism economy, and making the country a Top 20 global tourism destination by 2020.China is one of South Africa’s major non-African sources of tourist arrivals. To ensure a growing share of this booming market, South African tourism scholars and practitioners have to pay close attention to the behaviour of Chinese outbound tourists, particularly their destination choice behaviour. The Theory of Planned Behaviour (TPB)– an extension of the Theory of Reasoned Action (TRA)– can serve as a basis for researching destination choice. According to the TPB literature, intention is the most immediate and important determinant of behaviour. Three direct predictors of intention, namely, attitude, subjective norms, and perceived control, are functions of latent behavioural, normative, and control beliefs, respectively. The TPB is parsimonious but open to the inclusion of additional predictors if there is evidence that these predictors may explain a significant proportion of the variance in intention and behaviour after the basic predictors (attitude, subjective norms, and perceived control) have been accounted for. The current research successfully extended the TPB model for predicting potential Chinese tourists’ intentions to visit South Africa by adding two additional variables: travel motivation and travel constraints. The push-pull motivation framework discussed in the study postulates that people travel because they are pushed by internal forces (inner needs) and pulled by external forces (destination attributes). Typical barriers to travel include intrapersonal, interpersonal, and structural constraints. The new model makes an important contribution to the literature on destination choice, and provides South Africa’s destination marketers with suggestions for attracting and serving Chinese tourists. In addition, the research shows that both travel motivation and travel constraints can be used as bases for segmenting the outbound Chinese tourist market interested in visiting South Africa. A survey approach and a structured questionnaire distributed electronically to the online panel members of a Chinese market research company were instrumental in collecting the empirical data for the study. The questionnaire was originally written in English and translated into Chinese (Mandarin) via a blind translation-back-translation method. Attitude, subjective norms, perceived control, and visit intention were all operationalised as unidimensional and used scales adapted from previous studies. New scales were developed for travel motivation and travel constraints– both operationalised as multidimensional. Quota sampling, used to identify respondents aged 18 or older and living in Beijing, Shanghai, and Guangzhou, resulted in 630 usable questionnaires obtained from 1,510 sent invitation e-mails, yielding a response rate of 41.7%. The raw data collected were prepared through the sequential steps of editing, coding, and filing, and then analysed using both descriptive and inferential statistics. Descriptive analysis suggested that broadening personal horizons, viewing the natural scenery, and seeing something different were the top motives for visiting South Africa, while language, fear of crime, and lack of travel companions were the top barriers to visiting South Africa. According to the factor analysis, travel motivation had three underlying dimensions – learning, escape, and aesthetics and appreciation, while operational, risk and fear, and social barriers were three underlying dimensions of travel constraints. Regression analysis showed that the proposed extended TPB model had higher predictive power for visit intention than both TRA and TPB models; the basic predictors – attitude, subjective norms, and perceived control – all had a significant impact on visit intention; and in terms of the additional predictors, learning, operational constraints, and social constraints had a significant impact on visit intention. The analysis of variance indicated that travel frequency and age were the most profound background factors with an influence on the extended TPB model. Finally, cluster analysis resulted in two market segments with distinct profiles, that is, High-Motivation/ Low-Constraint (HMLC) tourists and Low-Motivation/High-Constraint (LMHC) tourists. Based on the theoretical and empirical findings of the current research, it is recommended that destination marketers in South Africa: advertise specific benefits of touring South Africa, namely, increasing knowledge, relieving stress, and enjoying high environmental quality, to advance Chinese residents’ perceptions of the country; develop tourism experiences that can be taken in a week or shorter to cater for the unique annual leave and public holiday policy in China; launch a media relations campaign in China to ensure that the facts about South Africa are communicated without distortion; collaborate with other destination stakeholders such as government and businesses, to actively attract and retain Chinese tourists for example by educating the public about Chinese culture and training employees to improve the quality of service; target the HMLC tourists via the Internet (particularly the social media) and by developing holiday packages that include activities related to cultural tourism, rest and relaxation, and nature-based tourism; and target the LMHC tourists by cooperating with local travel agencies and by developing holiday packages that highlight the diversity of tourism activities and offer value-added products/services.
- Full Text:
- Date Issued: 2014
- Authors: Han, Xiliang
- Date: 2014
- Subjects: Market segmentation , Tourists -- Attitudes , Sustainable tourism -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9325 , http://hdl.handle.net/10948/d1020945
- Description: The South African National Department of Tourism has recently initiated the National Tourism Sector Strategy aimed at developing a sustainable tourism economy, and making the country a Top 20 global tourism destination by 2020.China is one of South Africa’s major non-African sources of tourist arrivals. To ensure a growing share of this booming market, South African tourism scholars and practitioners have to pay close attention to the behaviour of Chinese outbound tourists, particularly their destination choice behaviour. The Theory of Planned Behaviour (TPB)– an extension of the Theory of Reasoned Action (TRA)– can serve as a basis for researching destination choice. According to the TPB literature, intention is the most immediate and important determinant of behaviour. Three direct predictors of intention, namely, attitude, subjective norms, and perceived control, are functions of latent behavioural, normative, and control beliefs, respectively. The TPB is parsimonious but open to the inclusion of additional predictors if there is evidence that these predictors may explain a significant proportion of the variance in intention and behaviour after the basic predictors (attitude, subjective norms, and perceived control) have been accounted for. The current research successfully extended the TPB model for predicting potential Chinese tourists’ intentions to visit South Africa by adding two additional variables: travel motivation and travel constraints. The push-pull motivation framework discussed in the study postulates that people travel because they are pushed by internal forces (inner needs) and pulled by external forces (destination attributes). Typical barriers to travel include intrapersonal, interpersonal, and structural constraints. The new model makes an important contribution to the literature on destination choice, and provides South Africa’s destination marketers with suggestions for attracting and serving Chinese tourists. In addition, the research shows that both travel motivation and travel constraints can be used as bases for segmenting the outbound Chinese tourist market interested in visiting South Africa. A survey approach and a structured questionnaire distributed electronically to the online panel members of a Chinese market research company were instrumental in collecting the empirical data for the study. The questionnaire was originally written in English and translated into Chinese (Mandarin) via a blind translation-back-translation method. Attitude, subjective norms, perceived control, and visit intention were all operationalised as unidimensional and used scales adapted from previous studies. New scales were developed for travel motivation and travel constraints– both operationalised as multidimensional. Quota sampling, used to identify respondents aged 18 or older and living in Beijing, Shanghai, and Guangzhou, resulted in 630 usable questionnaires obtained from 1,510 sent invitation e-mails, yielding a response rate of 41.7%. The raw data collected were prepared through the sequential steps of editing, coding, and filing, and then analysed using both descriptive and inferential statistics. Descriptive analysis suggested that broadening personal horizons, viewing the natural scenery, and seeing something different were the top motives for visiting South Africa, while language, fear of crime, and lack of travel companions were the top barriers to visiting South Africa. According to the factor analysis, travel motivation had three underlying dimensions – learning, escape, and aesthetics and appreciation, while operational, risk and fear, and social barriers were three underlying dimensions of travel constraints. Regression analysis showed that the proposed extended TPB model had higher predictive power for visit intention than both TRA and TPB models; the basic predictors – attitude, subjective norms, and perceived control – all had a significant impact on visit intention; and in terms of the additional predictors, learning, operational constraints, and social constraints had a significant impact on visit intention. The analysis of variance indicated that travel frequency and age were the most profound background factors with an influence on the extended TPB model. Finally, cluster analysis resulted in two market segments with distinct profiles, that is, High-Motivation/ Low-Constraint (HMLC) tourists and Low-Motivation/High-Constraint (LMHC) tourists. Based on the theoretical and empirical findings of the current research, it is recommended that destination marketers in South Africa: advertise specific benefits of touring South Africa, namely, increasing knowledge, relieving stress, and enjoying high environmental quality, to advance Chinese residents’ perceptions of the country; develop tourism experiences that can be taken in a week or shorter to cater for the unique annual leave and public holiday policy in China; launch a media relations campaign in China to ensure that the facts about South Africa are communicated without distortion; collaborate with other destination stakeholders such as government and businesses, to actively attract and retain Chinese tourists for example by educating the public about Chinese culture and training employees to improve the quality of service; target the HMLC tourists via the Internet (particularly the social media) and by developing holiday packages that include activities related to cultural tourism, rest and relaxation, and nature-based tourism; and target the LMHC tourists by cooperating with local travel agencies and by developing holiday packages that highlight the diversity of tourism activities and offer value-added products/services.
- Full Text:
- Date Issued: 2014
Citizenship rights : still a long road to travel - Graduation Ceremonies address 2014
- Authors: Badat, Saleem
- Date: 2014
- Language: English
- Type: Text
- Identifier: vital:7872 , http://hdl.handle.net/10962/d1016421
- Description: The 20th anniversary of our democracy is a good time to reflect on the progress that we have made with respect to citizenship in post-1994 South Africa. 1994 was a revolutionary breakthrough. From being a racially exclusive authoritarian society in which millions were downtrodden subjects, we became a democracy in which for the first time almost all inhabitants became citizens. Critical here was a commendable Constitution, including a Bill of Rights, which held out the promise of an extensive range of human, social and economic rights that did not exist for all or at all prior to 1994. During the past 20 years there have been significant economic and social gains and achievements. At the same time, there continue to be many challenges, and key institutions of our democracy have come under strain as a result of too many in power seeking to use the state as their private piggy bank. Still, a relatively independent judiciary, free media, autonomous universities and the like remain intact. Witness in this regard the magnificent performance of the Public Protector’s office under Thuli Madonsela. However, a number of contemporary realities, compromise the ideal of full and substantive citizenship rights for all that the Constitution promises. Indeed, they condemn large numbers of people to conditions that are associated with subjecthood and being subjects.
- Full Text:
- Date Issued: 2014
- Authors: Badat, Saleem
- Date: 2014
- Language: English
- Type: Text
- Identifier: vital:7872 , http://hdl.handle.net/10962/d1016421
- Description: The 20th anniversary of our democracy is a good time to reflect on the progress that we have made with respect to citizenship in post-1994 South Africa. 1994 was a revolutionary breakthrough. From being a racially exclusive authoritarian society in which millions were downtrodden subjects, we became a democracy in which for the first time almost all inhabitants became citizens. Critical here was a commendable Constitution, including a Bill of Rights, which held out the promise of an extensive range of human, social and economic rights that did not exist for all or at all prior to 1994. During the past 20 years there have been significant economic and social gains and achievements. At the same time, there continue to be many challenges, and key institutions of our democracy have come under strain as a result of too many in power seeking to use the state as their private piggy bank. Still, a relatively independent judiciary, free media, autonomous universities and the like remain intact. Witness in this regard the magnificent performance of the Public Protector’s office under Thuli Madonsela. However, a number of contemporary realities, compromise the ideal of full and substantive citizenship rights for all that the Constitution promises. Indeed, they condemn large numbers of people to conditions that are associated with subjecthood and being subjects.
- Full Text:
- Date Issued: 2014
Classification of the difficulty in accelerating problems using GPUs
- Authors: Tristram, Uvedale Roy
- Date: 2014
- Subjects: Graphics processing units , Computer algorithms , Computer programming , Problem solving -- Data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4699 , http://hdl.handle.net/10962/d1012978
- Description: Scientists continually require additional processing power, as this enables them to compute larger problem sizes, use more complex models and algorithms, and solve problems previously thought computationally impractical. General-purpose computation on graphics processing units (GPGPU) can help in this regard, as there is great potential in using graphics processors to accelerate many scientific models and algorithms. However, some problems are considerably harder to accelerate than others, and it may be challenging for those new to GPGPU to ascertain the difficulty of accelerating a particular problem or seek appropriate optimisation guidance. Through what was learned in the acceleration of a hydrological uncertainty ensemble model, large numbers of k-difference string comparisons, and a radix sort, problem attributes have been identified that can assist in the evaluation of the difficulty in accelerating a problem using GPUs. The identified attributes are inherent parallelism, branch divergence, problem size, required computational parallelism, memory access pattern regularity, data transfer overhead, and thread cooperation. Using these attributes as difficulty indicators, an initial problem difficulty classification framework has been created that aids in GPU acceleration difficulty evaluation. This framework further facilitates directed guidance on suggested optimisations and required knowledge based on problem classification, which has been demonstrated for the aforementioned accelerated problems. It is anticipated that this framework, or a derivative thereof, will prove to be a useful resource for new or novice GPGPU developers in the evaluation of potential problems for GPU acceleration.
- Full Text:
- Date Issued: 2014
- Authors: Tristram, Uvedale Roy
- Date: 2014
- Subjects: Graphics processing units , Computer algorithms , Computer programming , Problem solving -- Data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4699 , http://hdl.handle.net/10962/d1012978
- Description: Scientists continually require additional processing power, as this enables them to compute larger problem sizes, use more complex models and algorithms, and solve problems previously thought computationally impractical. General-purpose computation on graphics processing units (GPGPU) can help in this regard, as there is great potential in using graphics processors to accelerate many scientific models and algorithms. However, some problems are considerably harder to accelerate than others, and it may be challenging for those new to GPGPU to ascertain the difficulty of accelerating a particular problem or seek appropriate optimisation guidance. Through what was learned in the acceleration of a hydrological uncertainty ensemble model, large numbers of k-difference string comparisons, and a radix sort, problem attributes have been identified that can assist in the evaluation of the difficulty in accelerating a problem using GPUs. The identified attributes are inherent parallelism, branch divergence, problem size, required computational parallelism, memory access pattern regularity, data transfer overhead, and thread cooperation. Using these attributes as difficulty indicators, an initial problem difficulty classification framework has been created that aids in GPU acceleration difficulty evaluation. This framework further facilitates directed guidance on suggested optimisations and required knowledge based on problem classification, which has been demonstrated for the aforementioned accelerated problems. It is anticipated that this framework, or a derivative thereof, will prove to be a useful resource for new or novice GPGPU developers in the evaluation of potential problems for GPU acceleration.
- Full Text:
- Date Issued: 2014
Climate Change and Environmental Challenges in Southern African Development Community (SADC): Responses in the Age of Globalisation
- Chikunda, Charles, Mandikonza, Caleb
- Authors: Chikunda, Charles , Mandikonza, Caleb
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437249 , vital:73363 , ISBN 9789462098367 , https://brill.com/display/book/9789462098367/BP000009.xml
- Description: There is evidence that one of the greatest controversies facing Africa today is how to make sense of the two leading global intentions of the 21st century: sustainable development and globalisation. These two paradigms appear to have some op-posing tendencies within them, some of which are contestable. Globalisation advocates for liberalisation; reduction or elimina-tion of state regulations on the market, free reign, and a high degree of rights to the large corporations that dominate the market. Globalisation also entails the cross flow of knowledge and knowledge forms.
- Full Text:
- Date Issued: 2014
- Authors: Chikunda, Charles , Mandikonza, Caleb
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437249 , vital:73363 , ISBN 9789462098367 , https://brill.com/display/book/9789462098367/BP000009.xml
- Description: There is evidence that one of the greatest controversies facing Africa today is how to make sense of the two leading global intentions of the 21st century: sustainable development and globalisation. These two paradigms appear to have some op-posing tendencies within them, some of which are contestable. Globalisation advocates for liberalisation; reduction or elimina-tion of state regulations on the market, free reign, and a high degree of rights to the large corporations that dominate the market. Globalisation also entails the cross flow of knowledge and knowledge forms.
- Full Text:
- Date Issued: 2014
Climate change effects on animal and plant phylogenetic diversity in southern Africa
- Pio, Dorothea V, Engler, Robin, Linder, H Peter, Monadjem, Ara, Cotterill, Fenton P D, Taylor, Peter J, Schoeman, M Corrie, Price, Benjamin W, Villet, Martin H, Eick, Geeta, Salamin, Nicholas, Guisan, Antoine
- Authors: Pio, Dorothea V , Engler, Robin , Linder, H Peter , Monadjem, Ara , Cotterill, Fenton P D , Taylor, Peter J , Schoeman, M Corrie , Price, Benjamin W , Villet, Martin H , Eick, Geeta , Salamin, Nicholas , Guisan, Antoine
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441874 , vital:73930 , https://doi.org/10.1111/gcb.12524
- Description: Much attention has been paid to the effects of climate change on species' range reductions and extinctions. There is however surprisingly little information on how climate change driven threat may impact the tree of life and result in loss of phylogenetic diversity (PD). Some plant families and mammalian orders reveal nonrandom extinction patterns, but many other plant families do not. Do these discrepancies reflect different speciation histories and does climate induced extinction result in the same discrepancies among different groups? Answers to these questions require representative taxon sampling. Here, we combine phylogenetic analyses, species distribution modeling, and climate change projections on two of the largest plant families in the Cape Floristic Region (Proteaceae and Restionaceae), as well as the second most diverse mammalian order in Southern Africa (Chiroptera), and an herbivorous insect genus (Platypleura) in the family Cicadidae to answer this question. We model current and future species distributions to assess species threat levels over the next 70 years, and then compare projected with random PD survival. Results for these animal and plant clades reveal congruence. PD losses are not significantly higher under predicted extinction than under random extinction simulations. So far the evidence suggests that focusing resources on climate threatened species alone may not result in disproportionate benefits for the preservation of evolutionary history.
- Full Text:
- Date Issued: 2014
- Authors: Pio, Dorothea V , Engler, Robin , Linder, H Peter , Monadjem, Ara , Cotterill, Fenton P D , Taylor, Peter J , Schoeman, M Corrie , Price, Benjamin W , Villet, Martin H , Eick, Geeta , Salamin, Nicholas , Guisan, Antoine
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441874 , vital:73930 , https://doi.org/10.1111/gcb.12524
- Description: Much attention has been paid to the effects of climate change on species' range reductions and extinctions. There is however surprisingly little information on how climate change driven threat may impact the tree of life and result in loss of phylogenetic diversity (PD). Some plant families and mammalian orders reveal nonrandom extinction patterns, but many other plant families do not. Do these discrepancies reflect different speciation histories and does climate induced extinction result in the same discrepancies among different groups? Answers to these questions require representative taxon sampling. Here, we combine phylogenetic analyses, species distribution modeling, and climate change projections on two of the largest plant families in the Cape Floristic Region (Proteaceae and Restionaceae), as well as the second most diverse mammalian order in Southern Africa (Chiroptera), and an herbivorous insect genus (Platypleura) in the family Cicadidae to answer this question. We model current and future species distributions to assess species threat levels over the next 70 years, and then compare projected with random PD survival. Results for these animal and plant clades reveal congruence. PD losses are not significantly higher under predicted extinction than under random extinction simulations. So far the evidence suggests that focusing resources on climate threatened species alone may not result in disproportionate benefits for the preservation of evolutionary history.
- Full Text:
- Date Issued: 2014
Clinical experiences of third-year student nurses in a public college in the Eastern Cape
- Authors: Tyanti, Mandisa
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Nursing Science)
- Identifier: vital:11912 , http://hdl.handle.net/10353/d1016097
- Description: Clinical experience has always been an important part of nursing education. Nursing colleges require students to be placed in clinical areas in order to acquire new knowledge and skills. The purpose of the study was to explore and describe the clinical experiences during their clinical placement of the third-year student nurses at a public college in the Eastern Cape. The objectives of this study were: to explore and describe the experiences of the third-year student of a public nursing college in the Eastern Cape, and to describe strategies for the improvement of student learning during clinical practice. A qualitative, explorative and descriptive research design was used to describe the clinical experiences of these student nurses and the strategies for the improvement of student learning during clinical practice. Data were collected from focus group interviews, using a purposive and convenience sample from one college campus in the Eastern Cape. Tesch’s method of data analysis (in Creswell, 2003) was used to analyse data. Trustworthiness was ensured in this research by using Guba’s model (in Lincoln & Guba, 1985) of qualitative research. Ethical approval was obtained from the University of Fort Hare Research Ethics Committee, the Department of Health, Eastern Cape, the Head of the Nursing College, the Campus Head and the participants and ethical consideration was ensured throughout the research process. Themes and sub-themes emerged from data collected about the clinical experiences of the nurses. The study brought to light the experiences of third-year student nurses during allocation to clinical areas. The findings from this study revealed the need for proper clinical accompaniment by college staff to ensure that clinical learning is taking place. Strategies to improve learning in the clinical areas are described. and recommendations for nursing education and nursing practice are made. If this is applied, it will help the student nurses to be better professionals.
- Full Text:
- Date Issued: 2014
- Authors: Tyanti, Mandisa
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Nursing Science)
- Identifier: vital:11912 , http://hdl.handle.net/10353/d1016097
- Description: Clinical experience has always been an important part of nursing education. Nursing colleges require students to be placed in clinical areas in order to acquire new knowledge and skills. The purpose of the study was to explore and describe the clinical experiences during their clinical placement of the third-year student nurses at a public college in the Eastern Cape. The objectives of this study were: to explore and describe the experiences of the third-year student of a public nursing college in the Eastern Cape, and to describe strategies for the improvement of student learning during clinical practice. A qualitative, explorative and descriptive research design was used to describe the clinical experiences of these student nurses and the strategies for the improvement of student learning during clinical practice. Data were collected from focus group interviews, using a purposive and convenience sample from one college campus in the Eastern Cape. Tesch’s method of data analysis (in Creswell, 2003) was used to analyse data. Trustworthiness was ensured in this research by using Guba’s model (in Lincoln & Guba, 1985) of qualitative research. Ethical approval was obtained from the University of Fort Hare Research Ethics Committee, the Department of Health, Eastern Cape, the Head of the Nursing College, the Campus Head and the participants and ethical consideration was ensured throughout the research process. Themes and sub-themes emerged from data collected about the clinical experiences of the nurses. The study brought to light the experiences of third-year student nurses during allocation to clinical areas. The findings from this study revealed the need for proper clinical accompaniment by college staff to ensure that clinical learning is taking place. Strategies to improve learning in the clinical areas are described. and recommendations for nursing education and nursing practice are made. If this is applied, it will help the student nurses to be better professionals.
- Full Text:
- Date Issued: 2014
Cloud information security : a higher education perspective
- Authors: Van der Schyff, Karl Izak
- Date: 2014
- Subjects: Cloud computing -- Security measures , Information technology -- Security measures , Data protection , Internet in higher education , Education, Higher -- Technological innovations
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4692 , http://hdl.handle.net/10962/d1011607 , Cloud computing -- Security measures , Information technology -- Security measures , Data protection , Internet in higher education , Education, Higher -- Technological innovations
- Description: In recent years higher education institutions have come under increasing financial pressure. This has not only prompted universities to investigate more cost effective means of delivering course content and maintaining research output, but also to investigate the administrative functions that accompany them. As such, many South African universities have either adopted or are in the process of adopting some form of cloud computing given the recent drop in bandwidth costs. However, this adoption process has raised concerns about the security of cloud-based information and this has, in some cases, had a negative impact on the adoption process. In an effort to study these concerns many researchers have employed a positivist approach with little, if any, focus on the operational context of these universities. Moreover, there has been very little research, specifically within the South African context. This study addresses some of these concerns by investigating the threats and security incident response life cycle within a higher education cloud. This was done by initially conducting a small scale survey and a detailed thematic analysis of twelve interviews from three South African universities. The identified themes and their corresponding analyses and interpretation contribute on both a practical and theoretical level with the practical contributions relating to a set of security driven criteria for selecting cloud providers as well as recommendations for universities who have or are in the process of adopting cloud computing. Theoretically several conceptual frameworks are offered allowing the researcher to convey his understanding of how the aforementioned practical concepts relate to each other as well as the concepts that constitute the research questions of this study.
- Full Text:
- Date Issued: 2014
- Authors: Van der Schyff, Karl Izak
- Date: 2014
- Subjects: Cloud computing -- Security measures , Information technology -- Security measures , Data protection , Internet in higher education , Education, Higher -- Technological innovations
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4692 , http://hdl.handle.net/10962/d1011607 , Cloud computing -- Security measures , Information technology -- Security measures , Data protection , Internet in higher education , Education, Higher -- Technological innovations
- Description: In recent years higher education institutions have come under increasing financial pressure. This has not only prompted universities to investigate more cost effective means of delivering course content and maintaining research output, but also to investigate the administrative functions that accompany them. As such, many South African universities have either adopted or are in the process of adopting some form of cloud computing given the recent drop in bandwidth costs. However, this adoption process has raised concerns about the security of cloud-based information and this has, in some cases, had a negative impact on the adoption process. In an effort to study these concerns many researchers have employed a positivist approach with little, if any, focus on the operational context of these universities. Moreover, there has been very little research, specifically within the South African context. This study addresses some of these concerns by investigating the threats and security incident response life cycle within a higher education cloud. This was done by initially conducting a small scale survey and a detailed thematic analysis of twelve interviews from three South African universities. The identified themes and their corresponding analyses and interpretation contribute on both a practical and theoretical level with the practical contributions relating to a set of security driven criteria for selecting cloud providers as well as recommendations for universities who have or are in the process of adopting cloud computing. Theoretically several conceptual frameworks are offered allowing the researcher to convey his understanding of how the aforementioned practical concepts relate to each other as well as the concepts that constitute the research questions of this study.
- Full Text:
- Date Issued: 2014
Collection of urban tree products by households in poorer residential areas of three South African towns
- Kaoma, Humphrey, Shackleton, Charlie M
- Authors: Kaoma, Humphrey , Shackleton, Charlie M
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180980 , vital:43678 , xlink:href="https://doi.org/10.1016/j.ufug.2014.02.002"
- Description: The high rates of urban in-migration and poverty common in many developing country towns potentially increases the reliance of urban populations on the direct benefits provided by trees. Yet understanding of the extent of such use and the sources of these tree products is limited. Here we report on the extent of use of urban tree products by 450 households in the poorer areas of three towns along a rainfall gradient based on household questionnaires. We considered the proportion of households making use of each of several tree products and the collection or purchasing frequency which we disaggregated by source of the product, including trees in homesteads, urban spaces, edges of towns and via purchase from traders. Most households (91%) used firewood, which was most frequently collected from the urban fringe or purchased, although one-third at times also collected firewood from trees on their home plot. All households used fruits, most commonly sourced through purchase (98%), but nearly half of whom also supplemented by harvesting fruits from their home plot. Other products used included wood for building, fencing and utensils, herbal medicines, planting material and mulch. Collection of products from urban homestead trees was highest amongst households in the informal settlements and least in the more established townships. Residents of new low-cost housing areas made extensive use of urban tree products harvested in urban spaces because they had fewer homestead trees than residents of informal areas or townships. Overall, urban residents made use of a wide array of tangible products from trees which they sourced from a variety of places, including their homestead plot. This urges that planning agencies ensure that homestead plot sizes or other urban spaces that provide tree products are large enough to support the direct needs of poorer urban residents.
- Full Text:
- Date Issued: 2014
- Authors: Kaoma, Humphrey , Shackleton, Charlie M
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180980 , vital:43678 , xlink:href="https://doi.org/10.1016/j.ufug.2014.02.002"
- Description: The high rates of urban in-migration and poverty common in many developing country towns potentially increases the reliance of urban populations on the direct benefits provided by trees. Yet understanding of the extent of such use and the sources of these tree products is limited. Here we report on the extent of use of urban tree products by 450 households in the poorer areas of three towns along a rainfall gradient based on household questionnaires. We considered the proportion of households making use of each of several tree products and the collection or purchasing frequency which we disaggregated by source of the product, including trees in homesteads, urban spaces, edges of towns and via purchase from traders. Most households (91%) used firewood, which was most frequently collected from the urban fringe or purchased, although one-third at times also collected firewood from trees on their home plot. All households used fruits, most commonly sourced through purchase (98%), but nearly half of whom also supplemented by harvesting fruits from their home plot. Other products used included wood for building, fencing and utensils, herbal medicines, planting material and mulch. Collection of products from urban homestead trees was highest amongst households in the informal settlements and least in the more established townships. Residents of new low-cost housing areas made extensive use of urban tree products harvested in urban spaces because they had fewer homestead trees than residents of informal areas or townships. Overall, urban residents made use of a wide array of tangible products from trees which they sourced from a variety of places, including their homestead plot. This urges that planning agencies ensure that homestead plot sizes or other urban spaces that provide tree products are large enough to support the direct needs of poorer urban residents.
- Full Text:
- Date Issued: 2014
Colonisation and community structure of benthic diatoms on artificial substrates following a major flood event: a case of the Kowie River (Eastern Cape, South Africa)
- Dalu, Tatenda, Froneman, P William, Chari, Lenin D, Richoux, Nicole B
- Authors: Dalu, Tatenda , Froneman, P William , Chari, Lenin D , Richoux, Nicole B
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143357 , vital:38239 , http://dx.doi.org/10.4314/wsa.v40i3.10
- Description: A major flooding event that occurred during October–November 2012 caused major changes in the Kowie River hydromorphology and aquatic communities. The aim of our study was to identify the environmental variables that structure riverine benthic diatom communities at upstream and downstream locations 25 km apart on the Kowie River, South Africa. This was undertaken using tiles as artificial substrates so that we could study how the communities developed after the flood disturbance. The diatom community structure was assessed over a 28-day period following a flood event in October 2012. The Mann Whitney test indicated that there was a statistically significant difference (p 0.05) in total dissolved solids, salinity, pH and oxygen reduction potential between the two sites. In total, 58 diatom species belonging to 30 genera were identified over the 28-day study.
- Full Text:
- Date Issued: 2014
- Authors: Dalu, Tatenda , Froneman, P William , Chari, Lenin D , Richoux, Nicole B
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143357 , vital:38239 , http://dx.doi.org/10.4314/wsa.v40i3.10
- Description: A major flooding event that occurred during October–November 2012 caused major changes in the Kowie River hydromorphology and aquatic communities. The aim of our study was to identify the environmental variables that structure riverine benthic diatom communities at upstream and downstream locations 25 km apart on the Kowie River, South Africa. This was undertaken using tiles as artificial substrates so that we could study how the communities developed after the flood disturbance. The diatom community structure was assessed over a 28-day period following a flood event in October 2012. The Mann Whitney test indicated that there was a statistically significant difference (p 0.05) in total dissolved solids, salinity, pH and oxygen reduction potential between the two sites. In total, 58 diatom species belonging to 30 genera were identified over the 28-day study.
- Full Text:
- Date Issued: 2014
Combating corruption while respecting human rights : a critical study of the non-conviction based assets recovery mechanism in Kenya and South Africa
- Authors: Obura, Ken Otieno
- Date: 2014
- Subjects: Human rights -- Kenya , Human rights -- South Africa , Corruption -- Kenya , Corruption -- South Africa , Reparation (Criminal justice) -- Kenya , Reparation (Criminal justice) -- South Africa , Political corruption -- Kenya , Political corruption -- South Africa , Corruption investigation -- Kenya , Corruption investigation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3719 , http://hdl.handle.net/10962/d1013159
- Description: The thesis contributes to the search for sound anti-corruption laws and practices that are effective and fair. It argues for the respect for human rights in the crafting and implementation of anti-corruption laws as a requisite for successful control of corruption. The basis for this argument is threefold: First, human rights provide a framework for checking against abuse of state’s police power, an abuse which if allowed to take root, would make the fight against corruption lose its legitimacy in the eye of the people. Second, human rights ensure that the interest of individuals is catered for in the crafting of anti-corruption laws and practices thereby denying perpetrators of corruption legal excuses that can be exploited to delay or frustrate corruption cases in the courts of law. Third, human rights provide a useful framework for balancing competing interests in the area of corruption control – it enables society to craft measures that fulfils the public interest in the eradication of corruption while concomitantly assuring the competing public interest in the protection of individual members’ liberties – a condition that is necessary if the support of the holders of these competing interests is to be enlisted and fostered in the fight against corruption. The thesis focuses on the study of the non-conviction based assets recovery mechanism, a mechanism that allows the state to apply a procedure lacking in criminal law safeguards to address criminal behaviour. The mechanism is thus beset with avenues for abuse, which if unchecked could have debilitating effects not only to individual liberties but also to the long term legitimacy of the fight against corruption. In this regard, the thesis examines how the human rights framework has been used in Kenya and South Africa to check on the potential dangers of the non-conviction based mechanism and to provide for a proportional balance between the imperative of corruption control and the guarantee against arbitrary deprivation of property. The aim is to unravel the benefits of respecting human rights in the fight against corruption in general and in the non-conviction based assets recovery in particular. Kenya and South Africa are chosen for study because they provide two models of non-conviction based mechanisms with different levels of safeguards, for comparative consideration.
- Full Text:
- Date Issued: 2014
- Authors: Obura, Ken Otieno
- Date: 2014
- Subjects: Human rights -- Kenya , Human rights -- South Africa , Corruption -- Kenya , Corruption -- South Africa , Reparation (Criminal justice) -- Kenya , Reparation (Criminal justice) -- South Africa , Political corruption -- Kenya , Political corruption -- South Africa , Corruption investigation -- Kenya , Corruption investigation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3719 , http://hdl.handle.net/10962/d1013159
- Description: The thesis contributes to the search for sound anti-corruption laws and practices that are effective and fair. It argues for the respect for human rights in the crafting and implementation of anti-corruption laws as a requisite for successful control of corruption. The basis for this argument is threefold: First, human rights provide a framework for checking against abuse of state’s police power, an abuse which if allowed to take root, would make the fight against corruption lose its legitimacy in the eye of the people. Second, human rights ensure that the interest of individuals is catered for in the crafting of anti-corruption laws and practices thereby denying perpetrators of corruption legal excuses that can be exploited to delay or frustrate corruption cases in the courts of law. Third, human rights provide a useful framework for balancing competing interests in the area of corruption control – it enables society to craft measures that fulfils the public interest in the eradication of corruption while concomitantly assuring the competing public interest in the protection of individual members’ liberties – a condition that is necessary if the support of the holders of these competing interests is to be enlisted and fostered in the fight against corruption. The thesis focuses on the study of the non-conviction based assets recovery mechanism, a mechanism that allows the state to apply a procedure lacking in criminal law safeguards to address criminal behaviour. The mechanism is thus beset with avenues for abuse, which if unchecked could have debilitating effects not only to individual liberties but also to the long term legitimacy of the fight against corruption. In this regard, the thesis examines how the human rights framework has been used in Kenya and South Africa to check on the potential dangers of the non-conviction based mechanism and to provide for a proportional balance between the imperative of corruption control and the guarantee against arbitrary deprivation of property. The aim is to unravel the benefits of respecting human rights in the fight against corruption in general and in the non-conviction based assets recovery in particular. Kenya and South Africa are chosen for study because they provide two models of non-conviction based mechanisms with different levels of safeguards, for comparative consideration.
- Full Text:
- Date Issued: 2014
Community adaptation strategies to environmental degradation in the south west region of Cameroon
- Authors: Buh, Gilbert Ewi
- Date: 2014
- Subjects: Environmental degradation -- Cameroon , Sustainable development -- Cameroon , Irrigation -- Cameroon
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9189 , http://hdl.handle.net/10948/d1020301
- Description: The Republic of Cameroon (8-16°E; 2-13°N) is a Central African nation that borders the Bight of Biafra. It is home of about 20 million people and a country with great environmental and agricultural diversity that reflects Africa. It is known as ‘Africa Miniature’. Recent policies and administrative malfunctions has plunged the SWR into severe environmental problems that led to a cholera outbreak, claiming many lives. Community respond to these severe environmental problems in the SWR greatly left behind resilient strategies to reduce its spread. A mixed method of both qualitative and quantitative research approach was used by the researcher to come up with community strategies which this research seeks to address. Various conclusions such as community demand for support from the local government, sustainable irrigation programs, availability of pipe-borne water and environmental education were put in place, as possible solutions to the persisting environmental problems in the SWR.
- Full Text:
- Date Issued: 2014
- Authors: Buh, Gilbert Ewi
- Date: 2014
- Subjects: Environmental degradation -- Cameroon , Sustainable development -- Cameroon , Irrigation -- Cameroon
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9189 , http://hdl.handle.net/10948/d1020301
- Description: The Republic of Cameroon (8-16°E; 2-13°N) is a Central African nation that borders the Bight of Biafra. It is home of about 20 million people and a country with great environmental and agricultural diversity that reflects Africa. It is known as ‘Africa Miniature’. Recent policies and administrative malfunctions has plunged the SWR into severe environmental problems that led to a cholera outbreak, claiming many lives. Community respond to these severe environmental problems in the SWR greatly left behind resilient strategies to reduce its spread. A mixed method of both qualitative and quantitative research approach was used by the researcher to come up with community strategies which this research seeks to address. Various conclusions such as community demand for support from the local government, sustainable irrigation programs, availability of pipe-borne water and environmental education were put in place, as possible solutions to the persisting environmental problems in the SWR.
- Full Text:
- Date Issued: 2014
Community service professional nurses' experiences of bullying in state hospitals
- Authors: Yon, Gadieja
- Date: 2014
- Subjects: Public health nurses , Bullying in the workplace , State hospitals
- Language: English
- Type: Thesis , Masters , MCur
- Identifier: vital:10056 , http://hdl.handle.net/10948/d1018622
- Description: It is estimated that 80 percent of nurses experience some type of bullying in the workplace during their working lives, and bullying from colleagues has become a major concern. Bullying involves repeated forms of negative behaviours directed at a victim over time. More specifically, the victim is bullied repeatedly over time, with bullying ranging from mild to more severe forms that often go unreported. Bullying in the workplace may cause low self-esteem, depression and anxiety, physical illness and in some cases, the inability to work. The aim of this research study was to explore and describe community service professional nurses’ experiences of being bullied in state hospitals. The information gathered during the course of the study was used to develop strategies that can prevent the bullying of community service professional nurses in the workplace. The design of the study was qualitative, exploratory, descriptive, and contextual in nature. The population sample included all community service professional nurses in state hospitals in the Nelson Mandela Bay area. The researcher employed purposive sampling to select participants from the population of community service professional nurses employed at state hospitals. She collected data by conducting semi-structured individual interviews to gain in-depth accounts from participants and by making observations, which were captured in field notes. Data collected during the interviews were transcribed verbatim and analysed according to Tesch’s eight steps of analysis. Themes were identified through this process and compared to relevant literature. The researcher used the services of an independent coder to aid in the coding process. Trustworthiness was ensured by following Lincoln and Guba’s model of trustworthiness, which comprises the following concepts: credibility, transferability, dependability, and conformability. The researcher ensured that the study adhered to high ethical standards through the principles of justice, beneficence, non-maleficence, and respect for people.
- Full Text:
- Date Issued: 2014
- Authors: Yon, Gadieja
- Date: 2014
- Subjects: Public health nurses , Bullying in the workplace , State hospitals
- Language: English
- Type: Thesis , Masters , MCur
- Identifier: vital:10056 , http://hdl.handle.net/10948/d1018622
- Description: It is estimated that 80 percent of nurses experience some type of bullying in the workplace during their working lives, and bullying from colleagues has become a major concern. Bullying involves repeated forms of negative behaviours directed at a victim over time. More specifically, the victim is bullied repeatedly over time, with bullying ranging from mild to more severe forms that often go unreported. Bullying in the workplace may cause low self-esteem, depression and anxiety, physical illness and in some cases, the inability to work. The aim of this research study was to explore and describe community service professional nurses’ experiences of being bullied in state hospitals. The information gathered during the course of the study was used to develop strategies that can prevent the bullying of community service professional nurses in the workplace. The design of the study was qualitative, exploratory, descriptive, and contextual in nature. The population sample included all community service professional nurses in state hospitals in the Nelson Mandela Bay area. The researcher employed purposive sampling to select participants from the population of community service professional nurses employed at state hospitals. She collected data by conducting semi-structured individual interviews to gain in-depth accounts from participants and by making observations, which were captured in field notes. Data collected during the interviews were transcribed verbatim and analysed according to Tesch’s eight steps of analysis. Themes were identified through this process and compared to relevant literature. The researcher used the services of an independent coder to aid in the coding process. Trustworthiness was ensured by following Lincoln and Guba’s model of trustworthiness, which comprises the following concepts: credibility, transferability, dependability, and conformability. The researcher ensured that the study adhered to high ethical standards through the principles of justice, beneficence, non-maleficence, and respect for people.
- Full Text:
- Date Issued: 2014
Comparative phylogeography of five swallowtail butterfly species (Lepidoptera: Papilionidae) in South Africa : ecological and taxonomic implications.
- Authors: Neef, Götz-Georg
- Date: 2014
- Subjects: Swallowtail butterflies , Papilionidae -- South Africa , Phylogeography -- South Africa , Swallowtail butterflies -- Effect of habitat modification on , Biodiversity -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4266 , http://hdl.handle.net/10962/d1013574
- Description: With current biota under constant threat of extinction, it is important to ascertain where and how biological diversity is generated and partitioned. Phylogeographic studies can assist in the identification of places and processes that indicate the origin and maintenance of biodiversity. Forest fragmentation has a big effect on local extinction and loss of genetic diversity of forest-restricted taxa, along with divergence and speciation of forest biota. This study aims to understand the effects of these processes on a number of forest-dwelling butterflies using a comparative phylogeographic approach. Mitochondrial DNA of five different Papilio species with different degrees of forest specificity was analysed using phylogenetic methods. In addition, the subspecific taxonomy of P. ophidicephalus was investigated using morphometrics of discal spots on the wings and nuclear DNA analysis along with mitochondrial DNA analysis. The results show that the forest-restricted species (P. ophidicephalus and P. echerioides) have more genetic structure and less genetic diversity than the more generalist species (P. dardanus, P. demodocus and P. nireus). This could be due to inbreeding depression and bottlenecks caused by forest fragmentation. As forest patches become smaller, the population size is affected and that causes a loss in genetic diversity, and increasing habitat fragmentation disrupts gene flow. The intraspecific taxonomy of P. ophidicephalus is far from revealed. However, this study shows there is evidence for the different subspecies when comparing morphological results and genetic results. From the evidence provided here it is suggested that P. ophidicephalus should be divided into two separate species rather than five subspecies.
- Full Text:
- Date Issued: 2014
- Authors: Neef, Götz-Georg
- Date: 2014
- Subjects: Swallowtail butterflies , Papilionidae -- South Africa , Phylogeography -- South Africa , Swallowtail butterflies -- Effect of habitat modification on , Biodiversity -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4266 , http://hdl.handle.net/10962/d1013574
- Description: With current biota under constant threat of extinction, it is important to ascertain where and how biological diversity is generated and partitioned. Phylogeographic studies can assist in the identification of places and processes that indicate the origin and maintenance of biodiversity. Forest fragmentation has a big effect on local extinction and loss of genetic diversity of forest-restricted taxa, along with divergence and speciation of forest biota. This study aims to understand the effects of these processes on a number of forest-dwelling butterflies using a comparative phylogeographic approach. Mitochondrial DNA of five different Papilio species with different degrees of forest specificity was analysed using phylogenetic methods. In addition, the subspecific taxonomy of P. ophidicephalus was investigated using morphometrics of discal spots on the wings and nuclear DNA analysis along with mitochondrial DNA analysis. The results show that the forest-restricted species (P. ophidicephalus and P. echerioides) have more genetic structure and less genetic diversity than the more generalist species (P. dardanus, P. demodocus and P. nireus). This could be due to inbreeding depression and bottlenecks caused by forest fragmentation. As forest patches become smaller, the population size is affected and that causes a loss in genetic diversity, and increasing habitat fragmentation disrupts gene flow. The intraspecific taxonomy of P. ophidicephalus is far from revealed. However, this study shows there is evidence for the different subspecies when comparing morphological results and genetic results. From the evidence provided here it is suggested that P. ophidicephalus should be divided into two separate species rather than five subspecies.
- Full Text:
- Date Issued: 2014
Comparison between base metals and platinum group metals in nitrogen, M codoped TiO 2 (M= Fe, Cu, Pd, Os) for photocatalytic removal of an organic dye in water
- Kuvarega, Alex T, Mamba, Bhekie B, Krause, Rui W M
- Authors: Kuvarega, Alex T , Mamba, Bhekie B , Krause, Rui W M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125129 , vital:35734 , https://doi.org/10.1155/2014/962102
- Description: The photocatalytic performance of a number of nonmetal and metal codoped TiO2 for the degradation of eosin yellow under simulated solar radiation was investigated. The synthesised materials were characterised by FTIR, Raman spectroscopy, XRD, DRUV-Vis, SEM, and TEM.The N, metal codoped TiO2 containing 0.5 wt.% of the metal consisted mainly of the anatase phase, with a particle size range of 15–28 nm. The particles were largely spherical and shifted the absorption edge well into the visible region. Band gap reduction was more pronounced for the N, PGM codoped TiO2 compared to N, base metal codoped samples. Codoping led to an enhancement in the photocatalytic activity of the materials for the degradation of eosin yellow. N, Pd codoped TiO2 was the most effective photocatalyst (99.9% dye removal) while N, Cu codoped TiO2 showed the least activity (25.5% removal). The mechanism for the photocatalytic enhancement was proposed on the basis of formation of an electron deficient Schottky barrier at the semiconductor-metal interface, which acts as an electron sink and thus retards electron-hole recombination. It was shown that the ability of the photocatalyst to degrade the dye depends on the nature and type of the metal dopant in the codoped TiO2 system.
- Full Text:
- Date Issued: 2014
- Authors: Kuvarega, Alex T , Mamba, Bhekie B , Krause, Rui W M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125129 , vital:35734 , https://doi.org/10.1155/2014/962102
- Description: The photocatalytic performance of a number of nonmetal and metal codoped TiO2 for the degradation of eosin yellow under simulated solar radiation was investigated. The synthesised materials were characterised by FTIR, Raman spectroscopy, XRD, DRUV-Vis, SEM, and TEM.The N, metal codoped TiO2 containing 0.5 wt.% of the metal consisted mainly of the anatase phase, with a particle size range of 15–28 nm. The particles were largely spherical and shifted the absorption edge well into the visible region. Band gap reduction was more pronounced for the N, PGM codoped TiO2 compared to N, base metal codoped samples. Codoping led to an enhancement in the photocatalytic activity of the materials for the degradation of eosin yellow. N, Pd codoped TiO2 was the most effective photocatalyst (99.9% dye removal) while N, Cu codoped TiO2 showed the least activity (25.5% removal). The mechanism for the photocatalytic enhancement was proposed on the basis of formation of an electron deficient Schottky barrier at the semiconductor-metal interface, which acts as an electron sink and thus retards electron-hole recombination. It was shown that the ability of the photocatalyst to degrade the dye depends on the nature and type of the metal dopant in the codoped TiO2 system.
- Full Text:
- Date Issued: 2014
Comparison of fluorophore and peroxidase labeled aptamer assays for MUC1 detection in cancer cells
- Flanagan, Shane P, Limson, Janice L, Fogel, Ronen
- Authors: Flanagan, Shane P , Limson, Janice L , Fogel, Ronen
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431076 , vital:72742 , xlink:href="10.1109/BioCAS.2014.6981720"
- Description: Aptamers hold great promise for cancer diagnosis and therapy. Several biosensors incorporate aptamers as biorecognition elements for tumor markers although few evaluate their detection in a native conformation and cellular micro-environment. In this study, fluorophore and peroxidase labeled aptamer configurations were compared for the detection of MCF7 breast and SW620 colon cancer cell lines expressing the tumor marker MUC1. Fluorescence based detection showed selective binding to the cell lines relative to a nonbinding control sequence with sequence specific binding differences between MUC1 aptamers accredited to variation in the glycosylation state of expressed MUC1. The peroxidase labeled assay showed high detection sensitivity although low binding specificity was observed for the MUC1 aptamers to the cell lines. Results suggest that aptamers susceptible to non specific binding to cells may limit the applicability of enzymatic amplification to improve aptasensor sensitivity.
- Full Text:
- Date Issued: 2014
- Authors: Flanagan, Shane P , Limson, Janice L , Fogel, Ronen
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431076 , vital:72742 , xlink:href="10.1109/BioCAS.2014.6981720"
- Description: Aptamers hold great promise for cancer diagnosis and therapy. Several biosensors incorporate aptamers as biorecognition elements for tumor markers although few evaluate their detection in a native conformation and cellular micro-environment. In this study, fluorophore and peroxidase labeled aptamer configurations were compared for the detection of MCF7 breast and SW620 colon cancer cell lines expressing the tumor marker MUC1. Fluorescence based detection showed selective binding to the cell lines relative to a nonbinding control sequence with sequence specific binding differences between MUC1 aptamers accredited to variation in the glycosylation state of expressed MUC1. The peroxidase labeled assay showed high detection sensitivity although low binding specificity was observed for the MUC1 aptamers to the cell lines. Results suggest that aptamers susceptible to non specific binding to cells may limit the applicability of enzymatic amplification to improve aptasensor sensitivity.
- Full Text:
- Date Issued: 2014
Comparison of the biology of geographically distinct populations of the citrus pest, Thaumatotibia leucotreta (Meyrick)(Lepidoptera: Tortricidae)
- Opoku-Debrah, John K, Hill, Martin P, Knox, Caroline M, Moore, Sean D
- Authors: Opoku-Debrah, John K , Hill, Martin P , Knox, Caroline M , Moore, Sean D
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405769 , vital:70204 , xlink:href="https://hdl.handle.net/10520/EJC160246"
- Description: Baculovirus biopesticides are an important component of integrated pest management programmes worldwide. One such example is the Cryptophlebia leucotreta granulovirus (CrleGV) which is used for the control of false codling moth, Thaumatotibia (= Cryptophlebia) leucotreta (Meyrick) (Lepidoptera: Tortricidae), a pest of citrus and other crops in South Africa. A potential problem associated with constant application of viral biopesticides is the differing susceptibility to the virus observed between different geographic populations of the insect host. This could be related to a number of factors, including biological performance and fitness of the target insect population. This study compared a variety of phenotypic traits between geographically distinct T. leucotreta populations collected from the Addo, Marble Hall, Citrusdal and Nelspruit regions of South Africa, and reared under laboratory conditions for several generations. Traits including pupal mass, female fecundity, egg hatch, pupal survival, adult eclosion and developmental time were used as parameters to measure biological performance and fitness. Insects from the Citrusdal region of the Western Cape exhibited significantly lower pupal mass, female fecundity, egg hatch, pupal survival, adult eclosion and the longest duration in larval and pupal development compared to the other colonies investigated. This is the first study to report differences in the performance of laboratory reared T. leucotreta from different geographic locations, and the findings may have important implications for the application of viral biopesticides for the control of this pest in South Africa.
- Full Text:
- Date Issued: 2014
- Authors: Opoku-Debrah, John K , Hill, Martin P , Knox, Caroline M , Moore, Sean D
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405769 , vital:70204 , xlink:href="https://hdl.handle.net/10520/EJC160246"
- Description: Baculovirus biopesticides are an important component of integrated pest management programmes worldwide. One such example is the Cryptophlebia leucotreta granulovirus (CrleGV) which is used for the control of false codling moth, Thaumatotibia (= Cryptophlebia) leucotreta (Meyrick) (Lepidoptera: Tortricidae), a pest of citrus and other crops in South Africa. A potential problem associated with constant application of viral biopesticides is the differing susceptibility to the virus observed between different geographic populations of the insect host. This could be related to a number of factors, including biological performance and fitness of the target insect population. This study compared a variety of phenotypic traits between geographically distinct T. leucotreta populations collected from the Addo, Marble Hall, Citrusdal and Nelspruit regions of South Africa, and reared under laboratory conditions for several generations. Traits including pupal mass, female fecundity, egg hatch, pupal survival, adult eclosion and developmental time were used as parameters to measure biological performance and fitness. Insects from the Citrusdal region of the Western Cape exhibited significantly lower pupal mass, female fecundity, egg hatch, pupal survival, adult eclosion and the longest duration in larval and pupal development compared to the other colonies investigated. This is the first study to report differences in the performance of laboratory reared T. leucotreta from different geographic locations, and the findings may have important implications for the application of viral biopesticides for the control of this pest in South Africa.
- Full Text:
- Date Issued: 2014
Comparison of the population growth potential of South African loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtles
- Authors: Tucek, Jenny Bianka
- Date: 2014
- Subjects: Sea turtles -- Population viability analysis -- South Africa , Migratory animals -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/5032 , vital:20793
- Description: A beach conservation programme protecting nesting loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtles in South Africa was started in 1963. As initial numbers of nesting females were low for both species (107 loggerheads and 24 leatherbacks) it was proposed that the protection of eggs, hatchlings and nesting females along the nesting beach would induce population growth and prohibit local extinction. Today, 50 years later, the loggerhead population exceeds 650 females per annum, whereas the leatherback population counts about 65 nesting females per year. The trend for leatherback turtles is that the population has been stable for about 30 years whereas loggerheads are increasing exponentially. Thus, this thesis investigated several life-history traits to explain the differing responses to the ongoing beach conservation programme. Reproductive output and success were assessed for both species; it was hypothesised that environmental conditions are sub-optimal for leatherback turtles to reproduce successfully. It was ascertained that nesting loggerhead females deposit larger clutches than leatherbacks (112 ± SD 20 eggs and 100 ± SD 23 eggs, respectively), but that annual reproductive output per individual leatherback female exceeds that of loggerhead turtles (±700 eggs and ±448 eggs, respectively) because they exhibit a higher intra-seasonal nesting frequency (leatherbacks n = 7 and loggerheads n = 4 from Nel et al. 2013). Emergence success (i.e. the percentage of hatchlings produced) per nest was similar for both species (loggerhead 73.6 ± SD 27.68 % and leatherback turtles 73.8 ± SD 22.70 %), but as loggerhead turtles nest in greater numbers, i.e. producing more hatchlings per year, the absolute population growth potential favours the loggerhead turtle. The second factor investigated was sex ratio because sea turtles display temperature-dependent sex determination (TSD) where extreme incubation temperatures can skew the sex ratio (i.e. feminising or masculinising a clutch). It was suspected that leatherback turtles are male-biased as this is the southern-most rookery (for both species). Further, leatherback nests are generally closer to the high tide mark, which might induce a cooling effect. Standard histological techniques were applied to sex hatchlings and a generalized linear model (GLM) was used to approximate annual sex ratio. Loggerhead sex ratio (2009 - 2011) was estimated at 86.9 ± SE 0.35 % female-biased; however, sufficient replication for the leatherback population was only obtained for season 2010, which indicated a 97.1 % (95 % CI 93.3 - 98.7) female bias. Both species are, thus, highly female-biased, and current sex ratio for leatherback turtles is not prohibiting population growth. Current sex ratios, however, are not necessarily indicative of sex ratios in the past which would have induced present population growth. Thus, to account for present population growth profiles, sex ratios from the past needed to be ascertained. Annual sex ratios (1997 - 2011) were modelled from historical air and sea surface temperatures (SSTs) but no significant change over time was obtained for either loggerhead or leatherback turtles (linear regression; p ≥ 0.45). The average sex ratio over this 15-year period for the South African loggerhead turtle was approximated at 77.1 ± SE 3.36 % female-biased, whereas leatherbacks exhibited a 99.5 ± SE 0.24 % female bias. Re-analysing data from the mid-80s by Maxwell et al. (1988) also indicated a 77.4 % female bias for the South African loggerhead population. It is, therefore, highly likely that sex ratios of the South African loggerhead and leatherback sea turtle populations have been stable for at least three decades and are not accountable for the differing population growth profiles as they are displayed today. Another possibility that could explain the opposed population growth profiles is the time taken for animals to replace themselves, i.e. age at maturity. It was suspected that age at maturity for the South African loggerhead turtle is comparable with that for leatherbacks. Using data from a 30-year mutilation tagging experiment (i.e. notching), age at first reproduction for South African loggerhead females was estimated. Results ranged broadly but a mean of 36.2 ± SD 7.71 years was obtained using a Gaussian distribution. Age at reproduction of the South African leatherback turtle was not determined but the literature suggests a much younger age of 13.3 - 26.8 years (Zug & Parham 1996, Dutton et al. 2005, Avens et al. 2009, Jones et al. 2011). Therefore, population growth would favour leatherback turtles as they exhibit a much shorter generation time. Finally, it was concluded that all life-history parameters investigated favour leatherback turtles, yet loggerheads are displaying population growth. However, as there were no obvious constraints to population growth on the nesting beach, it is suspected that population growth of the South African leatherback turtle is either unobserved (due to inadequate monitoring not capturing sufficient numbers of nesting events to establish a trend) or that population growth is prohibited by some offshore factor such as industrial fisheries (or some other driver not yet identified). Monitoring should, thus, be expanded and offshore mortality monitored as the leatherback population nesting in South Africa is still critically endangered with nesting numbers dangerously low.
- Full Text:
- Date Issued: 2014
- Authors: Tucek, Jenny Bianka
- Date: 2014
- Subjects: Sea turtles -- Population viability analysis -- South Africa , Migratory animals -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/5032 , vital:20793
- Description: A beach conservation programme protecting nesting loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtles in South Africa was started in 1963. As initial numbers of nesting females were low for both species (107 loggerheads and 24 leatherbacks) it was proposed that the protection of eggs, hatchlings and nesting females along the nesting beach would induce population growth and prohibit local extinction. Today, 50 years later, the loggerhead population exceeds 650 females per annum, whereas the leatherback population counts about 65 nesting females per year. The trend for leatherback turtles is that the population has been stable for about 30 years whereas loggerheads are increasing exponentially. Thus, this thesis investigated several life-history traits to explain the differing responses to the ongoing beach conservation programme. Reproductive output and success were assessed for both species; it was hypothesised that environmental conditions are sub-optimal for leatherback turtles to reproduce successfully. It was ascertained that nesting loggerhead females deposit larger clutches than leatherbacks (112 ± SD 20 eggs and 100 ± SD 23 eggs, respectively), but that annual reproductive output per individual leatherback female exceeds that of loggerhead turtles (±700 eggs and ±448 eggs, respectively) because they exhibit a higher intra-seasonal nesting frequency (leatherbacks n = 7 and loggerheads n = 4 from Nel et al. 2013). Emergence success (i.e. the percentage of hatchlings produced) per nest was similar for both species (loggerhead 73.6 ± SD 27.68 % and leatherback turtles 73.8 ± SD 22.70 %), but as loggerhead turtles nest in greater numbers, i.e. producing more hatchlings per year, the absolute population growth potential favours the loggerhead turtle. The second factor investigated was sex ratio because sea turtles display temperature-dependent sex determination (TSD) where extreme incubation temperatures can skew the sex ratio (i.e. feminising or masculinising a clutch). It was suspected that leatherback turtles are male-biased as this is the southern-most rookery (for both species). Further, leatherback nests are generally closer to the high tide mark, which might induce a cooling effect. Standard histological techniques were applied to sex hatchlings and a generalized linear model (GLM) was used to approximate annual sex ratio. Loggerhead sex ratio (2009 - 2011) was estimated at 86.9 ± SE 0.35 % female-biased; however, sufficient replication for the leatherback population was only obtained for season 2010, which indicated a 97.1 % (95 % CI 93.3 - 98.7) female bias. Both species are, thus, highly female-biased, and current sex ratio for leatherback turtles is not prohibiting population growth. Current sex ratios, however, are not necessarily indicative of sex ratios in the past which would have induced present population growth. Thus, to account for present population growth profiles, sex ratios from the past needed to be ascertained. Annual sex ratios (1997 - 2011) were modelled from historical air and sea surface temperatures (SSTs) but no significant change over time was obtained for either loggerhead or leatherback turtles (linear regression; p ≥ 0.45). The average sex ratio over this 15-year period for the South African loggerhead turtle was approximated at 77.1 ± SE 3.36 % female-biased, whereas leatherbacks exhibited a 99.5 ± SE 0.24 % female bias. Re-analysing data from the mid-80s by Maxwell et al. (1988) also indicated a 77.4 % female bias for the South African loggerhead population. It is, therefore, highly likely that sex ratios of the South African loggerhead and leatherback sea turtle populations have been stable for at least three decades and are not accountable for the differing population growth profiles as they are displayed today. Another possibility that could explain the opposed population growth profiles is the time taken for animals to replace themselves, i.e. age at maturity. It was suspected that age at maturity for the South African loggerhead turtle is comparable with that for leatherbacks. Using data from a 30-year mutilation tagging experiment (i.e. notching), age at first reproduction for South African loggerhead females was estimated. Results ranged broadly but a mean of 36.2 ± SD 7.71 years was obtained using a Gaussian distribution. Age at reproduction of the South African leatherback turtle was not determined but the literature suggests a much younger age of 13.3 - 26.8 years (Zug & Parham 1996, Dutton et al. 2005, Avens et al. 2009, Jones et al. 2011). Therefore, population growth would favour leatherback turtles as they exhibit a much shorter generation time. Finally, it was concluded that all life-history parameters investigated favour leatherback turtles, yet loggerheads are displaying population growth. However, as there were no obvious constraints to population growth on the nesting beach, it is suspected that population growth of the South African leatherback turtle is either unobserved (due to inadequate monitoring not capturing sufficient numbers of nesting events to establish a trend) or that population growth is prohibited by some offshore factor such as industrial fisheries (or some other driver not yet identified). Monitoring should, thus, be expanded and offshore mortality monitored as the leatherback population nesting in South Africa is still critically endangered with nesting numbers dangerously low.
- Full Text:
- Date Issued: 2014
Competition between two aquatic macrophytes, Lagarosiphon major (Ridley) Moss (Hydrocharitaceae) and Myriophyllum spicatum Linnaeus (Haloragaceae) as influenced by substrate sediment and nutrients
- Martin, Grant D, Coetzee, Julie A
- Authors: Martin, Grant D , Coetzee, Julie A
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76925 , vital:30641 , https://doi.org/10.1016/j.aquabot.2013.11.001
- Description: Competition between two globally economic and ecologically important submerged aquatic macrophytes, Lagarosiphon major (Rid.) Moss ex Wager and Myriophyllum spicatum L., was studied in response to growing in different substrate nutrient and sediment treatments. Addition series experiments were conducted with mixed plantings of L. major and M. spicatum grown under two soil nutrient concentrations (high vs. low) and two sediment treatments (sand vs. loam). Competitive ability of the plants was determined using an inverse linear model of the total dry weights as the yield variable. In high nutrient sediment treatments, L. major was the stronger competitor relative to M. spicatum, with one L. major plant being competitively equivalent to 2.5 M. spicatum plants in terms of their respective ability to reduce L. major biomass. In the loam sediment treatments, L. major was an even stronger competitor relative to M. spicatum with one L. major being equivalent to 10 M. spicatum plants. Additionally, L. major had a faster relative growth rate (RGR) than M. spicatum when grown in mixed cultures, a loam sediment type and at both high and low planting densities. The results indicated that L. major is a superior competitor to M. spicatum and that both nutrient and sediment conditions significantly affect the competitive ability of both species. The results contribute to the understanding of competition between submerged invasive macrophytes, and provide insight into the establishment and spread of invasive submerged macrophytes.
- Full Text:
- Date Issued: 2014
- Authors: Martin, Grant D , Coetzee, Julie A
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76925 , vital:30641 , https://doi.org/10.1016/j.aquabot.2013.11.001
- Description: Competition between two globally economic and ecologically important submerged aquatic macrophytes, Lagarosiphon major (Rid.) Moss ex Wager and Myriophyllum spicatum L., was studied in response to growing in different substrate nutrient and sediment treatments. Addition series experiments were conducted with mixed plantings of L. major and M. spicatum grown under two soil nutrient concentrations (high vs. low) and two sediment treatments (sand vs. loam). Competitive ability of the plants was determined using an inverse linear model of the total dry weights as the yield variable. In high nutrient sediment treatments, L. major was the stronger competitor relative to M. spicatum, with one L. major plant being competitively equivalent to 2.5 M. spicatum plants in terms of their respective ability to reduce L. major biomass. In the loam sediment treatments, L. major was an even stronger competitor relative to M. spicatum with one L. major being equivalent to 10 M. spicatum plants. Additionally, L. major had a faster relative growth rate (RGR) than M. spicatum when grown in mixed cultures, a loam sediment type and at both high and low planting densities. The results indicated that L. major is a superior competitor to M. spicatum and that both nutrient and sediment conditions significantly affect the competitive ability of both species. The results contribute to the understanding of competition between submerged invasive macrophytes, and provide insight into the establishment and spread of invasive submerged macrophytes.
- Full Text:
- Date Issued: 2014