Indigenous People’s Detection of Rapid Ecological Change
- Lauer, Matthew, Aswani, Shankar
- Authors: Lauer, Matthew , Aswani, Shankar
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124811 , vital:35699 , https://doi.10.1111/cobi.12250
- Description: When sudden catastrophic events occur, it becomes critical for coastal communities to detect and respond to environmental transformations because failure to do so may undermine overall ecosystem resilience and threaten people’s livelihoods. We therefore asked how capable of detecting rapid ecological change following massive environmental disruptions local, indigenous people are. We assessed the direction and periodicity of experimental learning of people in the Western Solomon Islands after a tsunami in 2007. We compared the results of marine science surveys with local ecological knowledge of the benthos across 3 affected villages and 3 periods before and after the tsunami. We sought to determine how people recognize biophysical changes in the environment before and after catastrophic events such as earthquakes and tsunamis and whether people have the ability to detect ecological changes over short time scales or need longer time scales to recognize changes. Indigenous people were able to detect changes in the benthos over time. Detection levels differed between marine science surveys and local ecological knowledge sources over time, but overall patterns of statistically significant detection of change were evident for various habitats. Our findings have implications for marine conservation, coastal management policies, and disaster-relief efforts because when people are able to detect ecological changes, this, in turn, affects how they exploit and manage their marine resources.
- Full Text:
- Authors: Lauer, Matthew , Aswani, Shankar
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124811 , vital:35699 , https://doi.10.1111/cobi.12250
- Description: When sudden catastrophic events occur, it becomes critical for coastal communities to detect and respond to environmental transformations because failure to do so may undermine overall ecosystem resilience and threaten people’s livelihoods. We therefore asked how capable of detecting rapid ecological change following massive environmental disruptions local, indigenous people are. We assessed the direction and periodicity of experimental learning of people in the Western Solomon Islands after a tsunami in 2007. We compared the results of marine science surveys with local ecological knowledge of the benthos across 3 affected villages and 3 periods before and after the tsunami. We sought to determine how people recognize biophysical changes in the environment before and after catastrophic events such as earthquakes and tsunamis and whether people have the ability to detect ecological changes over short time scales or need longer time scales to recognize changes. Indigenous people were able to detect changes in the benthos over time. Detection levels differed between marine science surveys and local ecological knowledge sources over time, but overall patterns of statistically significant detection of change were evident for various habitats. Our findings have implications for marine conservation, coastal management policies, and disaster-relief efforts because when people are able to detect ecological changes, this, in turn, affects how they exploit and manage their marine resources.
- Full Text:
Indium phthalocyanine–CdSe/ZnS quantum dots nanocomposites showing size dependent and near ideal optical limiting behaviour
- Sanusi, Kayode, Nyokong, Tebello
- Authors: Sanusi, Kayode , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189921 , vital:44947 , xlink:href="https://doi.org/10.1016/j.optmat.2014.09.021"
- Description: Indium phthalocyanine–CdSe/ZnS quantum dots (QDs) nanocomposites (InPc–CdSe/ZnS) of three sizes (5.57, 8.12 and 8.75 nm) were synthesized according to known procedures. The particle size of the CdSe/ZnS QDs alone are 3.95, 6.02, and 6.66 nm, and are denoted as QD1, QD2 and QD3 respectively. The nonlinear absorption (NLA) properties of the nanoconjugates (InPc–CdSe/ZnS) were investigated with nanosecond laser radiation at 532 nm wavelength. Enhanced NLA properties compared to the InPc alone were observed in the conjugates. The NLA was found to increase with the size of the CdSe/ZnS particles attached to the phthalocyanine. The observed increase was due to the availability of more free-carrier ions in the larger QDs, thus giving rise to the enhanced free-carrier absorption. The measured free-carrier absorption cross-sections (σFCA) are 1.10, 1.65 and 1.95 (×10−19 cm2) for InPc-QD1, InPc-QD2 and InPc-QD3 respectively. The nanoconjugates (InPc–CdSe/ZnS) showed a much lower threshold for optical limiting together with a much lower transmission at high fluences, than the previously reported nanocomposite limiters.
- Full Text:
- Authors: Sanusi, Kayode , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189921 , vital:44947 , xlink:href="https://doi.org/10.1016/j.optmat.2014.09.021"
- Description: Indium phthalocyanine–CdSe/ZnS quantum dots (QDs) nanocomposites (InPc–CdSe/ZnS) of three sizes (5.57, 8.12 and 8.75 nm) were synthesized according to known procedures. The particle size of the CdSe/ZnS QDs alone are 3.95, 6.02, and 6.66 nm, and are denoted as QD1, QD2 and QD3 respectively. The nonlinear absorption (NLA) properties of the nanoconjugates (InPc–CdSe/ZnS) were investigated with nanosecond laser radiation at 532 nm wavelength. Enhanced NLA properties compared to the InPc alone were observed in the conjugates. The NLA was found to increase with the size of the CdSe/ZnS particles attached to the phthalocyanine. The observed increase was due to the availability of more free-carrier ions in the larger QDs, thus giving rise to the enhanced free-carrier absorption. The measured free-carrier absorption cross-sections (σFCA) are 1.10, 1.65 and 1.95 (×10−19 cm2) for InPc-QD1, InPc-QD2 and InPc-QD3 respectively. The nanoconjugates (InPc–CdSe/ZnS) showed a much lower threshold for optical limiting together with a much lower transmission at high fluences, than the previously reported nanocomposite limiters.
- Full Text:
Influence of local economic development strategic leaders on the formulation of the integrated development plan, Makana Municipality, Eastern Cape
- Authors: Nonxuba, Mnweba McNair
- Date: 2014
- Subjects: Local Economic Development (Programme) , Community development -- South Africa -- Grahamstown , Municipal government -- South Africa -- Grahamstown , Strategic planning -- South Africa -- Grahamstown , Grahamstown (South Africa) -- Economic conditions -- 21st century , South Africa -- Politics and government
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:832 , http://hdl.handle.net/10962/d1013176
- Description: The influence of local economic development strategic leaders on how Integrated Development Plans (IDP) are developed is critical to gain insights into strategic planning directed towards economically developing municipalities. Concisely, the aim of this qualitative study was to gain a multiple understanding of how LED strategic leaders, namely managers of the LED directorate and sub-directorates at Makana local municipality influenced the IDP formulation. The fact that these LED strategic leaders, ‘make consequential or strategic decisions’ suggests that their decisions have an influence on the IDP formulation. Thus, the key research question in this study was: How do LED strategic leaders at Makana local municipality influence the formulation of the IDP at this municipality? This qualitative research used purposive sampling of incidents upheld by LED Strategic leaders. A total of ten in-depth and semi-structured interviews were conducted with four LED strategic leaders regarding incidents of their perceived influence on the formulation of the Integrated Development Plan at Makana. The interviews were in-depth in order to gain a rich understanding of their perspectives of reality. As the number of LED strategic leaders was already very small, all the four leaders at Makana participated in this study. Interview data was transcribed and analyzed using open coding and constant comparison. Member check was conducted to enhance confirmability of the findings of this study. Findings indicate that LED strategic leaders perceived their influence on the formulation of the IDP Makana municipality in four varied ways. Predominantly, LED strategic leaders commonly perceived that they had influence in setting evidence-driven direction, and searching for fitness of activities and issues with LED strategy. Thereafter, the other ways in which these LED strategic leaders perceived how they influenced the IDP formulation involve the facilitation of clarity and local relevance of LED mandates, and finally the integration of multiple economic voices of stakeholders. This demonstrates that LED strategic leaders at Makana emphasize proactively managing strategy process rather than content in terms of identifying key opportunities and major economic drivers in the local milieu. Instead, they perceived their influence as characterized by enhancing compliance with bringing the process of municipal strategy formulation closer to stakeholders. Implications of these findings are highlighted.
- Full Text:
- Authors: Nonxuba, Mnweba McNair
- Date: 2014
- Subjects: Local Economic Development (Programme) , Community development -- South Africa -- Grahamstown , Municipal government -- South Africa -- Grahamstown , Strategic planning -- South Africa -- Grahamstown , Grahamstown (South Africa) -- Economic conditions -- 21st century , South Africa -- Politics and government
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:832 , http://hdl.handle.net/10962/d1013176
- Description: The influence of local economic development strategic leaders on how Integrated Development Plans (IDP) are developed is critical to gain insights into strategic planning directed towards economically developing municipalities. Concisely, the aim of this qualitative study was to gain a multiple understanding of how LED strategic leaders, namely managers of the LED directorate and sub-directorates at Makana local municipality influenced the IDP formulation. The fact that these LED strategic leaders, ‘make consequential or strategic decisions’ suggests that their decisions have an influence on the IDP formulation. Thus, the key research question in this study was: How do LED strategic leaders at Makana local municipality influence the formulation of the IDP at this municipality? This qualitative research used purposive sampling of incidents upheld by LED Strategic leaders. A total of ten in-depth and semi-structured interviews were conducted with four LED strategic leaders regarding incidents of their perceived influence on the formulation of the Integrated Development Plan at Makana. The interviews were in-depth in order to gain a rich understanding of their perspectives of reality. As the number of LED strategic leaders was already very small, all the four leaders at Makana participated in this study. Interview data was transcribed and analyzed using open coding and constant comparison. Member check was conducted to enhance confirmability of the findings of this study. Findings indicate that LED strategic leaders perceived their influence on the formulation of the IDP Makana municipality in four varied ways. Predominantly, LED strategic leaders commonly perceived that they had influence in setting evidence-driven direction, and searching for fitness of activities and issues with LED strategy. Thereafter, the other ways in which these LED strategic leaders perceived how they influenced the IDP formulation involve the facilitation of clarity and local relevance of LED mandates, and finally the integration of multiple economic voices of stakeholders. This demonstrates that LED strategic leaders at Makana emphasize proactively managing strategy process rather than content in terms of identifying key opportunities and major economic drivers in the local milieu. Instead, they perceived their influence as characterized by enhancing compliance with bringing the process of municipal strategy formulation closer to stakeholders. Implications of these findings are highlighted.
- Full Text:
Influence of non-synonymous sequence mutations on the architecture of HIV-1 clade C protease receptor site : docking and molecular dynamics studies
- Authors: Onywera, David Harris
- Date: 2014
- Subjects: HIV (Viruses) -- Research , HIV infections -- Treatment -- Research , HIV infections -- Chemotherapy , Protease inhibitors -- Research , Viruses -- Effect of drugs on -- Research , Antiretroviral agents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4116 , http://hdl.handle.net/10962/d1013133
- Description: Despite the current interventions to avert contagions and AIDS-related deaths, sub-Saharan Africa is still the region most severely affected by the HIV/AIDS pandemic, where clade C is the dominant circulating HIV-1 strain. The pol-encoded HIV-1 protease enzyme has been extensively exploited as a drug target. Protease inhibitors have been engineered within the framework of clade B, the commonest in America, Europe and Australia. Recent studies have attested the existence of sequence and catalytic disparities between clades B and C proteases that could upset drug susceptibilities. Emergence of drug-resistant associated mutations and combinatorial explosions due to recombination thwarts the attempt to stabilize the current highly active antiretroviral therapy (HAART) baseline. The project aimed at identifying the structural and molecular mechanisms hired by mutants to affect the efficacies of both FDA approved and Rhodes University (RU)-synthesized inhibitors, in order to define how current and or future drugs ought to be modified or synthesized with the intent of combating drug resistance. The rationale involved the generation of homology models of the HIV-1 sequences from the South African infants failing treatment with two protease inhibitors: lopinavir and ritonavir (as monitored by alterations in surrogate markers: CD4 cell count decline and viral load upsurge). Consistent with previous studies, we established nine polymorphisms: 12S, 15V, 19I, 36I, 41K, 63P, 69K, 89M, and 93L, linked to subtype C wild-type; some of which are associated with protease treatment in clade B. Even though we predicted two occurrence patterns of M46I, I54V and V82A mutations as V82A→I54V→M46I and I54V→V82A→M46V, other possibilities might exist. Mutations either caused a protracted or contracted active site cleft, which enforced differential drug responses. The in silico docking indicated susceptibility discordances between clades B and C in certain polymorphisms and non-polymorphisms. The RU-synthesized ligands displayed varied efficacies that were below those of the FDA approved protease inhibitors. The flaps underwent a wide range of structural motions to accommodate and stabilize the ligands. Computational analyses unravelled the need for these potential drugs to be restructured by (de novo) drug engineers to improve their binding fits, affinities, energies and interactions with multiple key protease residues in order to target resilient HIV-1 assemblages. Accumulating evidences on contrasting drug-choice interpretations from the Stanford HIVdb should act as an impetus for the customization of a HIVdb for the sub-Saharan subcontinent.
- Full Text:
- Authors: Onywera, David Harris
- Date: 2014
- Subjects: HIV (Viruses) -- Research , HIV infections -- Treatment -- Research , HIV infections -- Chemotherapy , Protease inhibitors -- Research , Viruses -- Effect of drugs on -- Research , Antiretroviral agents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4116 , http://hdl.handle.net/10962/d1013133
- Description: Despite the current interventions to avert contagions and AIDS-related deaths, sub-Saharan Africa is still the region most severely affected by the HIV/AIDS pandemic, where clade C is the dominant circulating HIV-1 strain. The pol-encoded HIV-1 protease enzyme has been extensively exploited as a drug target. Protease inhibitors have been engineered within the framework of clade B, the commonest in America, Europe and Australia. Recent studies have attested the existence of sequence and catalytic disparities between clades B and C proteases that could upset drug susceptibilities. Emergence of drug-resistant associated mutations and combinatorial explosions due to recombination thwarts the attempt to stabilize the current highly active antiretroviral therapy (HAART) baseline. The project aimed at identifying the structural and molecular mechanisms hired by mutants to affect the efficacies of both FDA approved and Rhodes University (RU)-synthesized inhibitors, in order to define how current and or future drugs ought to be modified or synthesized with the intent of combating drug resistance. The rationale involved the generation of homology models of the HIV-1 sequences from the South African infants failing treatment with two protease inhibitors: lopinavir and ritonavir (as monitored by alterations in surrogate markers: CD4 cell count decline and viral load upsurge). Consistent with previous studies, we established nine polymorphisms: 12S, 15V, 19I, 36I, 41K, 63P, 69K, 89M, and 93L, linked to subtype C wild-type; some of which are associated with protease treatment in clade B. Even though we predicted two occurrence patterns of M46I, I54V and V82A mutations as V82A→I54V→M46I and I54V→V82A→M46V, other possibilities might exist. Mutations either caused a protracted or contracted active site cleft, which enforced differential drug responses. The in silico docking indicated susceptibility discordances between clades B and C in certain polymorphisms and non-polymorphisms. The RU-synthesized ligands displayed varied efficacies that were below those of the FDA approved protease inhibitors. The flaps underwent a wide range of structural motions to accommodate and stabilize the ligands. Computational analyses unravelled the need for these potential drugs to be restructured by (de novo) drug engineers to improve their binding fits, affinities, energies and interactions with multiple key protease residues in order to target resilient HIV-1 assemblages. Accumulating evidences on contrasting drug-choice interpretations from the Stanford HIVdb should act as an impetus for the customization of a HIVdb for the sub-Saharan subcontinent.
- Full Text:
Informing the Responses of Water Service Delivery Institutions to Climate and Development Changes: A Case Study in the Amatole Region, Eastern Cape
- Hughes, Denis A, Mantel, Sukhmani K, Slaughter, Andrew R
- Authors: Hughes, Denis A , Mantel, Sukhmani K , Slaughter, Andrew R
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438140 , vital:73438 , ISBN 978-1-4312-0520-2 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2018-1-14.pdf
- Description: This report has been generated by the Water Research Commission (WRC) funded project Developing Climate Change Adaptation Measures and Decision-Support System for Selected South African Water Boards (Project No. K5/2018).
- Full Text:
- Authors: Hughes, Denis A , Mantel, Sukhmani K , Slaughter, Andrew R
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438140 , vital:73438 , ISBN 978-1-4312-0520-2 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2018-1-14.pdf
- Description: This report has been generated by the Water Research Commission (WRC) funded project Developing Climate Change Adaptation Measures and Decision-Support System for Selected South African Water Boards (Project No. K5/2018).
- Full Text:
Inside the river
- Authors: Buzani, Mangaliso Welcome
- Date: 2014
- Subjects: South African poetry (English) , Xhosa poetry
- Language: English , Xhosa
- Type: text , Thesis , Masters , MA
- Identifier: vital:5971
- Description: My collection is of imagistic associative poetry, influenced by Spanish and other kinds of modernism, and written in my two languages, isiXhosa and English. My approach to producing these poems is first via the mastery of sound, not on the actual meaning of a poem; working on the meaning would be the last stage. The language of each poem will be encountered as it comes down on the paper, leading me to the words meaningful for that particular poem.
- Full Text:
- Authors: Buzani, Mangaliso Welcome
- Date: 2014
- Subjects: South African poetry (English) , Xhosa poetry
- Language: English , Xhosa
- Type: text , Thesis , Masters , MA
- Identifier: vital:5971
- Description: My collection is of imagistic associative poetry, influenced by Spanish and other kinds of modernism, and written in my two languages, isiXhosa and English. My approach to producing these poems is first via the mastery of sound, not on the actual meaning of a poem; working on the meaning would be the last stage. The language of each poem will be encountered as it comes down on the paper, leading me to the words meaningful for that particular poem.
- Full Text:
Integrating customary practices and institutions into comanagement of small-scale fisheries:
- Kittinger, J N, Cinner, J E, Aswani, Shankar, White, A T
- Authors: Kittinger, J N , Cinner, J E , Aswani, Shankar , White, A T
- Date: 2014
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/178975 , vital:40099 , ISBN 9780520959606
- Description: This pioneering volume provides a blueprint for managing the challenges of ocean conservation using marine historical ecology—an interdisciplinary area of study that is helping society to gain a more in-depth understanding of past human-environmental interactions in coastal and marine ecosystems and of the ecological and social outcomes associated with these interactions. Developed by groundbreaking practitioners in the field, Marine Historical Ecology in Conservation highlights the innovative ways that historical ecology can be applied to improve conservation and management efforts in the oceans. The book focuses on four key challenges that confront marine conservation: (1) recovering endangered species, (2) conserving fisheries, (3) restoring ecosystems, and (4) engaging the public. Chapters emphasize real-world conservation scenarios appropriate for students, faculty, researchers, and practitioners in marine science, conservation biology, natural resource management, paleoecology, and marine and coastal archaeology. By focusing on success stories and applied solutions, this volume delivers the required up-to-date science and tools needed for restoration and protection of ocean and coastal ecosystems.
- Full Text:
- Authors: Kittinger, J N , Cinner, J E , Aswani, Shankar , White, A T
- Date: 2014
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/178975 , vital:40099 , ISBN 9780520959606
- Description: This pioneering volume provides a blueprint for managing the challenges of ocean conservation using marine historical ecology—an interdisciplinary area of study that is helping society to gain a more in-depth understanding of past human-environmental interactions in coastal and marine ecosystems and of the ecological and social outcomes associated with these interactions. Developed by groundbreaking practitioners in the field, Marine Historical Ecology in Conservation highlights the innovative ways that historical ecology can be applied to improve conservation and management efforts in the oceans. The book focuses on four key challenges that confront marine conservation: (1) recovering endangered species, (2) conserving fisheries, (3) restoring ecosystems, and (4) engaging the public. Chapters emphasize real-world conservation scenarios appropriate for students, faculty, researchers, and practitioners in marine science, conservation biology, natural resource management, paleoecology, and marine and coastal archaeology. By focusing on success stories and applied solutions, this volume delivers the required up-to-date science and tools needed for restoration and protection of ocean and coastal ecosystems.
- Full Text:
Inter-individual variability and phenotypic plasticity : the effect of the environment on the biogeography, population structure, ecophysiology and reproduction of the sandhoppers Talorchestia capensis and Africorchestia quadrispinosa
- Authors: Baldanzi, Simone
- Date: 2014
- Subjects: Phenotypic plasticity -- Research -- Africa, Southern Talitridae -- Research -- Africa, Southern Amphipoda -- Research -- Africa, Southern Climatic changes -- Environmental aspects -- Africa, Southern Marine biology -- Africa, Southern Adaptation (Biology) -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5846 , http://hdl.handle.net/10962/d1011447
- Description: Climatic envelope models focus on the climatic variables affecting species or species assemblages, and are important tools to investigate the effect of climate change on their geographical ranges. These models have largely been proposed in order to make successful predictions on species‘ persistence, determining which variables are likely to induce range expansion, contraction, or shifting. More recent models, including the ability and the cost for individuals to respond promptly to an environmental stimulus, have revealed that species may express phenotypic plasticity able to induce adaptation to the new environment. Consequently, understanding how species evolve to a changing climate is fundamental. From this perspective, investigating intraspecific responses to an environmental variable may contribute to better understanding and prediction of the effect of climate change on the geographical range and evolution of species, particularly in the case of widespread species. In this context, the present study aimed at establishing how environmental variables (focussing mainly on temperature) may have contributed to shape the spatial distribution, physiology, reproductive biology and connectivity of two species of Southern African sandhoppers (Talorchestia capensis and Africorchestia quadrispinosa, Amphipoda, Talitridae). Most of the work was carried out on T. capensis, due to its widespread spatial distribution. A first investigation of the biogeography of T. capensis and A. quadrispinosa, revealed that, for both species, spatial patterns of abundance, size and sex ratio were not explained by the Abundant Centre Hypothesis (greater abundance at the core of a spatial range), but rather guided by bio-physical forces. Precisely, the abundance of sandhoppers was driven by the morphodynamic state of the beach, salinity and temperatures, with strong differentiation among sites that reflected local environmental conditions. In support of these findings, strong population structure in the genetics of T. capensis was found (three main groups) when investigating its phylogeography and genetic connectivity. Although such defined structure may suggests cryptic speciation, the concomitant within-population variation in the COX1 region of mtDNA, also highlighted the importance of individual genetic variability. High individual variability was also found in the response of T. capensis to temperature, both in its physiology (thermal plasticity) and its reproductive biology (maternal effects). Since temperature is one of the main variables affecting the coastal marine systems of southern Africa and the metabolism of animals in general, its effect on the physiology and reproduction of T. capensis was therefore investigated. Thermal responses to increasing/decreasing temperatures were assessed for separated populations of T. capensis. Individual variability was reported in the oxygen consumption of T. capensis in response to temperature (high variation around the means, especially for increasing temperatures). Among population differences in thermal sensitivity were significantly correlated with air temperature variability experienced over the past 23 years, highlighting the importance of historical temperature fluctuations to the current thermal physiology of these sandhoppers. Temperature also had an important effect on the reproductive plasticity of T. capensis. Different temperatures induced mothers to adjust the size of their offspring (i.e. egg size), with larger eggs produced at lower temperatures. Interestingly, females showed strongly significant among individual variation in the size of the eggs. Given the importance of understanding rapid responses of organisms to climate change and considering the fundamental role played by phenotypic plasticity in evolution, the overall study revealed the significance of individual plasticity and variability in response to the environment and highlighted its importance. Particularly, studying the thermal physiology of separated populations and understanding within population reproductive plasticity in response to temperature, helped to clarify how differences among individual responses have important consequences at the population level, possibly explaining the widespread distribution of T. capensis.
- Full Text:
- Authors: Baldanzi, Simone
- Date: 2014
- Subjects: Phenotypic plasticity -- Research -- Africa, Southern Talitridae -- Research -- Africa, Southern Amphipoda -- Research -- Africa, Southern Climatic changes -- Environmental aspects -- Africa, Southern Marine biology -- Africa, Southern Adaptation (Biology) -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5846 , http://hdl.handle.net/10962/d1011447
- Description: Climatic envelope models focus on the climatic variables affecting species or species assemblages, and are important tools to investigate the effect of climate change on their geographical ranges. These models have largely been proposed in order to make successful predictions on species‘ persistence, determining which variables are likely to induce range expansion, contraction, or shifting. More recent models, including the ability and the cost for individuals to respond promptly to an environmental stimulus, have revealed that species may express phenotypic plasticity able to induce adaptation to the new environment. Consequently, understanding how species evolve to a changing climate is fundamental. From this perspective, investigating intraspecific responses to an environmental variable may contribute to better understanding and prediction of the effect of climate change on the geographical range and evolution of species, particularly in the case of widespread species. In this context, the present study aimed at establishing how environmental variables (focussing mainly on temperature) may have contributed to shape the spatial distribution, physiology, reproductive biology and connectivity of two species of Southern African sandhoppers (Talorchestia capensis and Africorchestia quadrispinosa, Amphipoda, Talitridae). Most of the work was carried out on T. capensis, due to its widespread spatial distribution. A first investigation of the biogeography of T. capensis and A. quadrispinosa, revealed that, for both species, spatial patterns of abundance, size and sex ratio were not explained by the Abundant Centre Hypothesis (greater abundance at the core of a spatial range), but rather guided by bio-physical forces. Precisely, the abundance of sandhoppers was driven by the morphodynamic state of the beach, salinity and temperatures, with strong differentiation among sites that reflected local environmental conditions. In support of these findings, strong population structure in the genetics of T. capensis was found (three main groups) when investigating its phylogeography and genetic connectivity. Although such defined structure may suggests cryptic speciation, the concomitant within-population variation in the COX1 region of mtDNA, also highlighted the importance of individual genetic variability. High individual variability was also found in the response of T. capensis to temperature, both in its physiology (thermal plasticity) and its reproductive biology (maternal effects). Since temperature is one of the main variables affecting the coastal marine systems of southern Africa and the metabolism of animals in general, its effect on the physiology and reproduction of T. capensis was therefore investigated. Thermal responses to increasing/decreasing temperatures were assessed for separated populations of T. capensis. Individual variability was reported in the oxygen consumption of T. capensis in response to temperature (high variation around the means, especially for increasing temperatures). Among population differences in thermal sensitivity were significantly correlated with air temperature variability experienced over the past 23 years, highlighting the importance of historical temperature fluctuations to the current thermal physiology of these sandhoppers. Temperature also had an important effect on the reproductive plasticity of T. capensis. Different temperatures induced mothers to adjust the size of their offspring (i.e. egg size), with larger eggs produced at lower temperatures. Interestingly, females showed strongly significant among individual variation in the size of the eggs. Given the importance of understanding rapid responses of organisms to climate change and considering the fundamental role played by phenotypic plasticity in evolution, the overall study revealed the significance of individual plasticity and variability in response to the environment and highlighted its importance. Particularly, studying the thermal physiology of separated populations and understanding within population reproductive plasticity in response to temperature, helped to clarify how differences among individual responses have important consequences at the population level, possibly explaining the widespread distribution of T. capensis.
- Full Text:
Interaction of multiple stressors: vulnerability, coping and adaptation within the context of climate change and HIV/AIDS in South Africa: Investigating strategies to strengthen livelihoods and food security and build resilience
- Hamer, Nicholas G, Shackleton, Sheona E
- Authors: Hamer, Nicholas G , Shackleton, Sheona E
- Date: 2014
- Subjects: Climatic changes -- Economic aspects -- Eastern Cape (South Africa) Climatic changes -- South Africa Climatic changes -- Social aspects -- South Africa
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/50065 , vital:25956
- Description: Government policy development and implementation is often designed to address different sectors of society in isolation, so social, economic and environmental issues are considered as being distinct from one other. Recently it has been acknowledged that 'working in silos' is not conducive for good governance and so efforts have been made for better co-ordination between different government departments and different spheres of government. Our research findings show the knock on effects of one problem into other areas of people's lives, highlighting why it is vital for policies and programmes to be far better co-ordinated. The different challenges and stresses that people face in their lives interact with one another in complex ways, undermining their capacity to cope with and adapt to future changes, such as those expected under climate change.
- Full Text:
- Authors: Hamer, Nicholas G , Shackleton, Sheona E
- Date: 2014
- Subjects: Climatic changes -- Economic aspects -- Eastern Cape (South Africa) Climatic changes -- South Africa Climatic changes -- Social aspects -- South Africa
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/50065 , vital:25956
- Description: Government policy development and implementation is often designed to address different sectors of society in isolation, so social, economic and environmental issues are considered as being distinct from one other. Recently it has been acknowledged that 'working in silos' is not conducive for good governance and so efforts have been made for better co-ordination between different government departments and different spheres of government. Our research findings show the knock on effects of one problem into other areas of people's lives, highlighting why it is vital for policies and programmes to be far better co-ordinated. The different challenges and stresses that people face in their lives interact with one another in complex ways, undermining their capacity to cope with and adapt to future changes, such as those expected under climate change.
- Full Text:
Interactive efficacies of Elephantorrhiza elephantina and Pentanisia prunelloides extracts and isolated compounds against gastrointestinal bacteria
- Mpofu, Smart J, Olivier, D K, Krause, Rui W M, Ndinteh, Derek T, Van Vuuren, S
- Authors: Mpofu, Smart J , Olivier, D K , Krause, Rui W M , Ndinteh, Derek T , Van Vuuren, S
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124122 , vital:35552 , https://doi.org/10.1016/j.sajb.2014.07.002
- Description: Elephantorrhiza elephantina (Burch.) Skeels (Fabaceae) and Pentanisia prunelloides (Klotzsch ex Eckl. & Zeyh.) Walp. (Rubiaceae) are two medicinal plants used extensively in southern Africa to treat various ailments. Often, decoctions and infusions from these two plants are used in combination specifically for stomach ailments. The antimicrobial activities of the methanol and aqueous extracts of the rhizomes of the two plants, as well as the two active ingredients from the plants [(−)-epicatechin and palmitic acid] have been determined apart and in combination against Enterococcus faecalis (ATCC 29212), Escherichia coli (ATCC 8739) and Bacillus cereus (ATCC 11778). The minimum inhibitory concentration (MIC) values for the aqueous (0.50–16.00 mg/mL) and methanol (0.20–16.00 mg/mL) extracts independently demonstrated varied efficacies depending on the pathogen of study. When the two plants were combined in 1:1 ratios, synergistic to additive interactions (ΣFIC values 0.19–1.00) were noted. Efficacy for the two major compounds ranged between 0.13–0.63 mg/mL and mainly synergistic interactions were noted against E. faecalis and E. coli. The predominantly synergistic interactions noted between E. elephantina and P. prunelloides and major compounds, when tested in various ratios against these pathogens, provide some validation as to the traditional use of these two plants to treat bacterial gastrointestinal infections.
- Full Text:
- Authors: Mpofu, Smart J , Olivier, D K , Krause, Rui W M , Ndinteh, Derek T , Van Vuuren, S
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124122 , vital:35552 , https://doi.org/10.1016/j.sajb.2014.07.002
- Description: Elephantorrhiza elephantina (Burch.) Skeels (Fabaceae) and Pentanisia prunelloides (Klotzsch ex Eckl. & Zeyh.) Walp. (Rubiaceae) are two medicinal plants used extensively in southern Africa to treat various ailments. Often, decoctions and infusions from these two plants are used in combination specifically for stomach ailments. The antimicrobial activities of the methanol and aqueous extracts of the rhizomes of the two plants, as well as the two active ingredients from the plants [(−)-epicatechin and palmitic acid] have been determined apart and in combination against Enterococcus faecalis (ATCC 29212), Escherichia coli (ATCC 8739) and Bacillus cereus (ATCC 11778). The minimum inhibitory concentration (MIC) values for the aqueous (0.50–16.00 mg/mL) and methanol (0.20–16.00 mg/mL) extracts independently demonstrated varied efficacies depending on the pathogen of study. When the two plants were combined in 1:1 ratios, synergistic to additive interactions (ΣFIC values 0.19–1.00) were noted. Efficacy for the two major compounds ranged between 0.13–0.63 mg/mL and mainly synergistic interactions were noted against E. faecalis and E. coli. The predominantly synergistic interactions noted between E. elephantina and P. prunelloides and major compounds, when tested in various ratios against these pathogens, provide some validation as to the traditional use of these two plants to treat bacterial gastrointestinal infections.
- Full Text:
Intimacy, sex and sexuality : the experiences of vertically-infected HIV-positive adolescents
- Authors: Smaill, Lindsay Ann
- Date: 2014
- Subjects: Teenagers -- Sexual behavior , HIV-positive youth -- South Africa -- Eastern Cape , HIV infections -- Social aspects -- South Africa -- Eastern Cape , HIV infections -- Transmission -- South Africa -- Eastern Cape , Teenagers -- Diseases -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3225 , http://hdl.handle.net/10962/d1013026
- Description: This research explores the lived experience of being a vertically or prenatally-infected HIV-positive adolescent. It looks specifically at how the participants experience intimacy, sex and sexuality. HIV/AIDS remains a global pandemic and vertically-infected adolescents are a growing new demographic. However, there is a poverty of research, and therefore interventions and support, for this demographic. This qualitative research conducted six individual, in-depth, semi-structured, psychoanalytic research interviews with three participants. The interviews were structured around projective drawings that the participants did in the course of each interview. The interviews were transcribed and analysed using psychodynamic object relations theory and organised through interpretative phenomenological analysis. Every effort was made to ensure that the research was conducted ethically and validly. The analysis found that the participants' experience of intimacy has resulted in a self that is constantly under threat. This in turn has negatively impacted on the participants' experience of sex and sexuality. The implication of this research is that more in-depth research needs to be done into this demographic so that better interventions and support may be offered.
- Full Text:
- Authors: Smaill, Lindsay Ann
- Date: 2014
- Subjects: Teenagers -- Sexual behavior , HIV-positive youth -- South Africa -- Eastern Cape , HIV infections -- Social aspects -- South Africa -- Eastern Cape , HIV infections -- Transmission -- South Africa -- Eastern Cape , Teenagers -- Diseases -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3225 , http://hdl.handle.net/10962/d1013026
- Description: This research explores the lived experience of being a vertically or prenatally-infected HIV-positive adolescent. It looks specifically at how the participants experience intimacy, sex and sexuality. HIV/AIDS remains a global pandemic and vertically-infected adolescents are a growing new demographic. However, there is a poverty of research, and therefore interventions and support, for this demographic. This qualitative research conducted six individual, in-depth, semi-structured, psychoanalytic research interviews with three participants. The interviews were structured around projective drawings that the participants did in the course of each interview. The interviews were transcribed and analysed using psychodynamic object relations theory and organised through interpretative phenomenological analysis. Every effort was made to ensure that the research was conducted ethically and validly. The analysis found that the participants' experience of intimacy has resulted in a self that is constantly under threat. This in turn has negatively impacted on the participants' experience of sex and sexuality. The implication of this research is that more in-depth research needs to be done into this demographic so that better interventions and support may be offered.
- Full Text:
Invariant optimal control on the three-dimensional semi-Euclidean group: control affine and quadratic Hamilton-Poisson systems
- Authors: Barrett, Dennis Ian
- Date: 2014
- Subjects: Automorphisms , Symmetry (Mathematics) , Lyapunov stability , Geometry, Riemannian , Geometry, Affine , Elliptic functions
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/64805 , vital:28605
- Description: In this thesis we consider invariant control systems and Hamilton-Poisson systems on the three dimensional semi-Euclidean group SE(1,1). We first classify the left-invariant control affine systems (under detached feedback equivalence). We provide a complete list of normal forms, as well as classifying conditions. As a corollary to this classification, we derive controllability criteria for control affine systems on SE(1,1). Secondly, we consider quadratic Hamilton-Poisson systems on the (minus) Lie-Poisson space se(1,1)*. These systems are classified up to an affine isomorphism. Six normal forms are identified for the homogeneous case, whereas sixteen representatives (including several infinite families) are obtained for the inhomogeneous systems. Thereafter we consider the stability and integration of the normal forms obtained. For all homogeneous systems, and a subclass of inhomogeneous systems, we perform a complete stability analysis and derive explicit expressions for all integral curves. (The extremal controls of a large class of optimal control problems on SE(1,1) are linearly related to these integral curves.) Lastly, we discuss the Riemannian and sub-Riemannian problems. The (left-invariant) Riemannian and sub-Riemannian structures on SE(1,1) are classified, up to isometric group automorphisms and scaling. Explicit expressions for the geodesics of the normalised structures are found.
- Full Text:
- Authors: Barrett, Dennis Ian
- Date: 2014
- Subjects: Automorphisms , Symmetry (Mathematics) , Lyapunov stability , Geometry, Riemannian , Geometry, Affine , Elliptic functions
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/64805 , vital:28605
- Description: In this thesis we consider invariant control systems and Hamilton-Poisson systems on the three dimensional semi-Euclidean group SE(1,1). We first classify the left-invariant control affine systems (under detached feedback equivalence). We provide a complete list of normal forms, as well as classifying conditions. As a corollary to this classification, we derive controllability criteria for control affine systems on SE(1,1). Secondly, we consider quadratic Hamilton-Poisson systems on the (minus) Lie-Poisson space se(1,1)*. These systems are classified up to an affine isomorphism. Six normal forms are identified for the homogeneous case, whereas sixteen representatives (including several infinite families) are obtained for the inhomogeneous systems. Thereafter we consider the stability and integration of the normal forms obtained. For all homogeneous systems, and a subclass of inhomogeneous systems, we perform a complete stability analysis and derive explicit expressions for all integral curves. (The extremal controls of a large class of optimal control problems on SE(1,1) are linearly related to these integral curves.) Lastly, we discuss the Riemannian and sub-Riemannian problems. The (left-invariant) Riemannian and sub-Riemannian structures on SE(1,1) are classified, up to isometric group automorphisms and scaling. Explicit expressions for the geodesics of the normalised structures are found.
- Full Text:
Invasive alien species as drivers in socio-ecological systems: Local adaptations towards use of Lantana in Southern India
- Kannan, Ramesh, Shackleton, Charlie M, Shaanker, Ramanan U
- Authors: Kannan, Ramesh , Shackleton, Charlie M , Shaanker, Ramanan U
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180932 , vital:43671 , xlink:href="https://doi.org/10.1007/s10668-013-9500-y"
- Description: Lantana camara. L (hereafter Lantana) was first introduced by the British into India in 1807 as an ornamental plant. Since then the species has spread across the length and breadth of the country. Attempts to control Lantana in India have not been successful. In this study, we analysed the use of Lantana by local communities in southern India and identified the possible causes and consequences of its use through the use of a household survey of the socio-economic profile of the user and nonuser households and an analysis of the ecological history of the communities. Communities have been using Lantana for over 25–30 years and apparently such use was not prompted by external agencies. The characteristics of user and nonuser households were similar, except that Lantana users were more literate and had a greater number of occupations per household than nonusers. Per capita income was similar between user and nonuser groups. For nonuser groups, their main income sources were from trading (44 %), wage labour (32 %) and forest resources (23 %). In contrast, the Lantana user groups substituted their loss of income from forest resources (7 %) by income from Lantana (46 %). The ecological history revealed that Lantana was adopted as a resource at a time when it was increasing in the landscape and traditional bamboo resources were in decline because of overuse by commercial enterprises and mast flowering. This change in ecological resource availability prompted a major shift in livelihoods for some in the area.
- Full Text:
- Authors: Kannan, Ramesh , Shackleton, Charlie M , Shaanker, Ramanan U
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180932 , vital:43671 , xlink:href="https://doi.org/10.1007/s10668-013-9500-y"
- Description: Lantana camara. L (hereafter Lantana) was first introduced by the British into India in 1807 as an ornamental plant. Since then the species has spread across the length and breadth of the country. Attempts to control Lantana in India have not been successful. In this study, we analysed the use of Lantana by local communities in southern India and identified the possible causes and consequences of its use through the use of a household survey of the socio-economic profile of the user and nonuser households and an analysis of the ecological history of the communities. Communities have been using Lantana for over 25–30 years and apparently such use was not prompted by external agencies. The characteristics of user and nonuser households were similar, except that Lantana users were more literate and had a greater number of occupations per household than nonusers. Per capita income was similar between user and nonuser groups. For nonuser groups, their main income sources were from trading (44 %), wage labour (32 %) and forest resources (23 %). In contrast, the Lantana user groups substituted their loss of income from forest resources (7 %) by income from Lantana (46 %). The ecological history revealed that Lantana was adopted as a resource at a time when it was increasing in the landscape and traditional bamboo resources were in decline because of overuse by commercial enterprises and mast flowering. This change in ecological resource availability prompted a major shift in livelihoods for some in the area.
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Investigating coral reef ethnobiology in the western Solomon Islands for enhancing livelihood resilience:
- Authors: Aswani, Shankar
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145425 , vital:38437 , DOI: 10.15286/jps.123.3.237-276
- Description: Coral reefs are of great socio-economic and cultural importance for many coastal communities across the tropics, yet little is known about people's local classifications and their social and ecological relationships with these habitats. In the case of island peoples, coral reefs are more than just resource exploitation areas; they are also géomorphologie features that allow or bar people from navigating, markers that define property rights of the seascape in relation to other coastal and terrestrial habitats, and cultural and historical features that embody tribal identity and ideology. Building upon over two decades of research, this paper uses published and unpublished data to describe people's ecological and socio-economic relationships with coral reefs in two extensive lagoon ecosystems in the Western Solomon Islands.
- Full Text:
- Authors: Aswani, Shankar
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145425 , vital:38437 , DOI: 10.15286/jps.123.3.237-276
- Description: Coral reefs are of great socio-economic and cultural importance for many coastal communities across the tropics, yet little is known about people's local classifications and their social and ecological relationships with these habitats. In the case of island peoples, coral reefs are more than just resource exploitation areas; they are also géomorphologie features that allow or bar people from navigating, markers that define property rights of the seascape in relation to other coastal and terrestrial habitats, and cultural and historical features that embody tribal identity and ideology. Building upon over two decades of research, this paper uses published and unpublished data to describe people's ecological and socio-economic relationships with coral reefs in two extensive lagoon ecosystems in the Western Solomon Islands.
- Full Text:
Investigating how problem solving skills can be developed using a collaborative learning environment
- Authors: Sonne, Anita
- Date: 2014
- Subjects: Mathematics -- Study and teaching (Elementary) -- South Africa , Social learning , Active learning , Problem solving in children , Educational equalization -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1977 , http://hdl.handle.net/10962/d1013017
- Description: This thesis examines whether problem solving strategies develop and improve through working in a collaborative environment and, if so, how. The study explored the way peer-topeer discussions which are focussed on finding solutions to mathematical problems might shape learners' attitudes and participation in mathematical problem solving. I use the Vygotskian (1978) socio-cultural perspective where the process of learning takes place within the Zone of Proximal Development (ZPD). Polya's problem solving heuristics (Polya, 1973) and Kilpatrick's "Instructional Triangle" (Kilpatrick, Swafford & Findell, 2001) provided the analytical framework for the study. Seven grade 7 learners from a Ex-Model C school, volunteered to participate in the study. The data gathering process involved an initial problem solving assessment, a written questionnaire, observations and video recordings of the seven learners during a series of after school problem solving sessions and post intervention learner interviews. The study showed that group discussion can have a positive impact on learners' problem solving in several respects: My key findings point to: Mathematical communication does play a role in development of problem solving strategies. A more knowledgeable other, with regards to Vygotsky's (1978) ZPD and Kilpatrick et al's (2001) instructional triangle is a critical factor in the development of problem solving strategies. All five strands of Kilpatrick et al., (2001), strands for mathematical proficiency are required for correct solutions to be calculated. At times Polya's (1973) steps for problem solving move at a rapid pace and are difficult to notice. These steps develop at different speeds for different people.
- Full Text:
Investigating how problem solving skills can be developed using a collaborative learning environment
- Authors: Sonne, Anita
- Date: 2014
- Subjects: Mathematics -- Study and teaching (Elementary) -- South Africa , Social learning , Active learning , Problem solving in children , Educational equalization -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1977 , http://hdl.handle.net/10962/d1013017
- Description: This thesis examines whether problem solving strategies develop and improve through working in a collaborative environment and, if so, how. The study explored the way peer-topeer discussions which are focussed on finding solutions to mathematical problems might shape learners' attitudes and participation in mathematical problem solving. I use the Vygotskian (1978) socio-cultural perspective where the process of learning takes place within the Zone of Proximal Development (ZPD). Polya's problem solving heuristics (Polya, 1973) and Kilpatrick's "Instructional Triangle" (Kilpatrick, Swafford & Findell, 2001) provided the analytical framework for the study. Seven grade 7 learners from a Ex-Model C school, volunteered to participate in the study. The data gathering process involved an initial problem solving assessment, a written questionnaire, observations and video recordings of the seven learners during a series of after school problem solving sessions and post intervention learner interviews. The study showed that group discussion can have a positive impact on learners' problem solving in several respects: My key findings point to: Mathematical communication does play a role in development of problem solving strategies. A more knowledgeable other, with regards to Vygotsky's (1978) ZPD and Kilpatrick et al's (2001) instructional triangle is a critical factor in the development of problem solving strategies. All five strands of Kilpatrick et al., (2001), strands for mathematical proficiency are required for correct solutions to be calculated. At times Polya's (1973) steps for problem solving move at a rapid pace and are difficult to notice. These steps develop at different speeds for different people.
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Investigating the chaperone properties of a novel heat shock protein, Hsp70. c, from Trypanosoma brucei
- Burger, Adélle, Ludewig, Michael H, Boshoff, Aileen
- Authors: Burger, Adélle , Ludewig, Michael H , Boshoff, Aileen
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431155 , vital:72749 , xlink:href="https://doi.org/10.1155/2014/172582"
- Description: The neglected tropical disease, African Trypanosomiasis, is fatal and has a crippling impact on economic development. Heat shock protein 70 (Hsp70) is an important molecular chaperone that is expressed in response to stress and Hsp40 acts as its co-chaperone. These proteins play a wide range of roles in the cell and they are required to assist the parasite as it moves from a cold blooded insect vector to a warm blooded mammalian host. A novel cytosolic Hsp70, from Trypanosoma brucei, TbHsp70.c, contains an acidic substrate binding domain and lacks the C-terminal EEVD motif.The ability of a cytosolic Hsp40 from Trypanosoma brucei J protein 2, Tbj2, to function as a co-chaperone of TbHsp70.c was investigated.The main objective was to functionally characterize TbHsp70.c to further expand our knowledge of parasite biology. TbHsp70.c and Tbj2 were heterologously expressed and purified and both proteins displayed the ability to suppress aggregation of thermolabile MDH and chemically denatured rhodanese. ATPase assays revealed a 2.8-fold stimulation of the ATPase activity of TbHsp70.c by Tbj2. TbHsp70.c and Tbj2 both demonstrated chaperone activity and Tbj2 functions as a co-chaperone of TbHsp70.c.In vivo heat stress experiments indicated upregulation of the expression levels of TbHsp70.c.
- Full Text:
- Authors: Burger, Adélle , Ludewig, Michael H , Boshoff, Aileen
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431155 , vital:72749 , xlink:href="https://doi.org/10.1155/2014/172582"
- Description: The neglected tropical disease, African Trypanosomiasis, is fatal and has a crippling impact on economic development. Heat shock protein 70 (Hsp70) is an important molecular chaperone that is expressed in response to stress and Hsp40 acts as its co-chaperone. These proteins play a wide range of roles in the cell and they are required to assist the parasite as it moves from a cold blooded insect vector to a warm blooded mammalian host. A novel cytosolic Hsp70, from Trypanosoma brucei, TbHsp70.c, contains an acidic substrate binding domain and lacks the C-terminal EEVD motif.The ability of a cytosolic Hsp40 from Trypanosoma brucei J protein 2, Tbj2, to function as a co-chaperone of TbHsp70.c was investigated.The main objective was to functionally characterize TbHsp70.c to further expand our knowledge of parasite biology. TbHsp70.c and Tbj2 were heterologously expressed and purified and both proteins displayed the ability to suppress aggregation of thermolabile MDH and chemically denatured rhodanese. ATPase assays revealed a 2.8-fold stimulation of the ATPase activity of TbHsp70.c by Tbj2. TbHsp70.c and Tbj2 both demonstrated chaperone activity and Tbj2 functions as a co-chaperone of TbHsp70.c.In vivo heat stress experiments indicated upregulation of the expression levels of TbHsp70.c.
- Full Text:
Investigating the English vocabulary needs, exposure, and knowledge of isiXhosa speaking learners for transition from learning to read in the Foundation Phase to reading to learn in the Intermediate Phase : a case study
- Authors: Sibanda, Jabulani
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1968 , http://hdl.handle.net/10962/d1011790
- Description: The nature of learners' transition from Grade 3 to Grade 4 has serious and far reaching ramifications for their educational success in the subsequent grades. This is true of the South African education system, as it is for several other education contexts. The challenge that complicates the transition is largely a lexical one. It is with that understanding that the present study aimed to do three things namely: to determine the vocabulary needs of Grade 3 learners for transitioning to Grade 4; to establish the extent to which Grade 3 isiXhosa speaking learners are exposed to, and prepared for, the acquisition of that requisite vocabulary; and to establish the extent of Grade 4 learners' knowledge of that vocabulary at the beginning of the year. The vocabulary needs of Grade 3 learners for the transition to Grade 4 were determined from the Grade 4 subject textbook corpus. Word frequency was the criterion used to determine the usefulness and critical importance of a word for the transition. The AntConc concordance software program was used to generate word frequencies. Words with high frequency across the different subject areas, which were confirmed as high frequent in four other known word lists, were considered as constituting the vocabulary needs of learners at the verge of this significant transition. The extent of learners' preparedness for transitioning to Grade 4 in terms of their vocabulary exposure and vocabulary instruction was determined through teacher interviews, classroom observations, analysis of teacher classroom talk, analysis of the exposure and recycling of high frequent vocabulary in Grade 3 reading materials and classroom print. From these diverse sources, findings point to a paucity in both the exposure and recycling of the requisite vocabulary in these sources of classroom language input. Classroom observations and teacher interviews attest to lack of deliberate vocabulary instruction in the Grade 3 English First Additional Language lessons. The only extensive coverage of the requisite vocabulary was in the Grade 3 reading materials which included Big books, Readers and Workbooks. The Grade 4 learners' knowledge of the 60 high frequency words was tested through nine vocabulary tests, three of which tested their knowledge of word recognition, three tested passive word knowledge and the remaining three tested learners' active word knowledge. All the Grade 4 learners in the ten participating schools (297) were tested. Performance in the tests indicated that Grade 4 learners' knowledge of words requisite for reading to learn was low. That observation was consistent with an analysis of learners' performance per school, per district, per word, per test and per word bands. Tests of word recognition were done better than those of passive word knowledge and active word knowledge. Particularly problematic was test 4 which tested learners' knowledge of definition of words.
- Full Text:
- Authors: Sibanda, Jabulani
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1968 , http://hdl.handle.net/10962/d1011790
- Description: The nature of learners' transition from Grade 3 to Grade 4 has serious and far reaching ramifications for their educational success in the subsequent grades. This is true of the South African education system, as it is for several other education contexts. The challenge that complicates the transition is largely a lexical one. It is with that understanding that the present study aimed to do three things namely: to determine the vocabulary needs of Grade 3 learners for transitioning to Grade 4; to establish the extent to which Grade 3 isiXhosa speaking learners are exposed to, and prepared for, the acquisition of that requisite vocabulary; and to establish the extent of Grade 4 learners' knowledge of that vocabulary at the beginning of the year. The vocabulary needs of Grade 3 learners for the transition to Grade 4 were determined from the Grade 4 subject textbook corpus. Word frequency was the criterion used to determine the usefulness and critical importance of a word for the transition. The AntConc concordance software program was used to generate word frequencies. Words with high frequency across the different subject areas, which were confirmed as high frequent in four other known word lists, were considered as constituting the vocabulary needs of learners at the verge of this significant transition. The extent of learners' preparedness for transitioning to Grade 4 in terms of their vocabulary exposure and vocabulary instruction was determined through teacher interviews, classroom observations, analysis of teacher classroom talk, analysis of the exposure and recycling of high frequent vocabulary in Grade 3 reading materials and classroom print. From these diverse sources, findings point to a paucity in both the exposure and recycling of the requisite vocabulary in these sources of classroom language input. Classroom observations and teacher interviews attest to lack of deliberate vocabulary instruction in the Grade 3 English First Additional Language lessons. The only extensive coverage of the requisite vocabulary was in the Grade 3 reading materials which included Big books, Readers and Workbooks. The Grade 4 learners' knowledge of the 60 high frequency words was tested through nine vocabulary tests, three of which tested their knowledge of word recognition, three tested passive word knowledge and the remaining three tested learners' active word knowledge. All the Grade 4 learners in the ten participating schools (297) were tested. Performance in the tests indicated that Grade 4 learners' knowledge of words requisite for reading to learn was low. That observation was consistent with an analysis of learners' performance per school, per district, per word, per test and per word bands. Tests of word recognition were done better than those of passive word knowledge and active word knowledge. Particularly problematic was test 4 which tested learners' knowledge of definition of words.
- Full Text:
Investigating the role of mycorrhizal fungi and associated bacteria in promoting growth of citrus seedlings
- Authors: Sitole, Phumeza
- Date: 2014
- Subjects: Mycorrhizal fungi , Citrus -- South Africa , Citrus -- Diseases and pests -- Biological control -- South Africa , Fungi as biological pest control agents , Bacteria , Phytophthora , Pythium , Indoleacetic acid
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4111 , http://hdl.handle.net/10962/d1013033
- Description: South Africa is the world's second largest exporter of fresh citrus and is ranked 14th in citrus production. Fungal pathogens such as Phytophthora and Pythium cause economic losses as a result of root rot and brown rot. Mycorrhizal fungi are specialized members of the fungal community forming a mutualistic relationship with plant roots. Mycorrhizal fungal structures are known to associate with other soil microorganisms and these may contribute to improved plant growth. A diverse group of bacteria that interact with the mycorrhizal fungi are known as Mycorrhizal Helper Bacteria (MHB). The aim of this study was to investigate the role of arbuscular mycorrhiza and associated bacteria isolated from spores and determine whether they had any plant growth promoting potential. A total of 19 bacteria were isolated from arbuscular mycorrhizal spores and were molecularly identified as belonging to several Bacillus, Micrococcus, Onchrobactrum and Staphylococcus sp. All bacterial isolates were tested for plant growth promotion abilities. One Bacillus isolate was able to solubilise phosphate. Four isolates Micrococcus sp, Micrococcus leteus, Ochrobacterum sp and Ochrobacterum antropi were able to produce Indole Acetic Acid and three isolates showed potential to reduce growth of Phytophthora nicotianae, P. citrocola and P. citrophthora in in vitro plate cultures. Further tests using culture supernatants of the Bacillus sp, Micrococcus sp and Bacillus cereus confirmed their ability to inhibit or reduce growth of the three Phytophthora species in a 96 well bioassay. Bacillus sp and Bacillus cereus were able to inhibit Phytophthora spp by 95 to 100 % and Micrococcus spp was able to decrease pathogen growth by 60 to 94 %. These bacterial isolates were further evaluated for plant growth promoting abilities on citrus rough lemon seedlings alone or in combination with arbuscular mycorrhizal inoculum. Bacterial and mycorrhizal inoculants influence the increase in shoot and root biomass. Bacillus cereus in combination with mycorrhizal inoculum significantly increased seedling shoot to root ratio while root biomass was significantly increased with mycorrhizal inoculation. Due to the short duration of the trial mycorrhizal colonisation could not be assessed. It is evident that selected combinations of bacteria and mycorrhizal fungi could promote citrus seedling growth and potentially improve seedling health. Further studies under nursery conditions are recommended.
- Full Text:
- Authors: Sitole, Phumeza
- Date: 2014
- Subjects: Mycorrhizal fungi , Citrus -- South Africa , Citrus -- Diseases and pests -- Biological control -- South Africa , Fungi as biological pest control agents , Bacteria , Phytophthora , Pythium , Indoleacetic acid
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4111 , http://hdl.handle.net/10962/d1013033
- Description: South Africa is the world's second largest exporter of fresh citrus and is ranked 14th in citrus production. Fungal pathogens such as Phytophthora and Pythium cause economic losses as a result of root rot and brown rot. Mycorrhizal fungi are specialized members of the fungal community forming a mutualistic relationship with plant roots. Mycorrhizal fungal structures are known to associate with other soil microorganisms and these may contribute to improved plant growth. A diverse group of bacteria that interact with the mycorrhizal fungi are known as Mycorrhizal Helper Bacteria (MHB). The aim of this study was to investigate the role of arbuscular mycorrhiza and associated bacteria isolated from spores and determine whether they had any plant growth promoting potential. A total of 19 bacteria were isolated from arbuscular mycorrhizal spores and were molecularly identified as belonging to several Bacillus, Micrococcus, Onchrobactrum and Staphylococcus sp. All bacterial isolates were tested for plant growth promotion abilities. One Bacillus isolate was able to solubilise phosphate. Four isolates Micrococcus sp, Micrococcus leteus, Ochrobacterum sp and Ochrobacterum antropi were able to produce Indole Acetic Acid and three isolates showed potential to reduce growth of Phytophthora nicotianae, P. citrocola and P. citrophthora in in vitro plate cultures. Further tests using culture supernatants of the Bacillus sp, Micrococcus sp and Bacillus cereus confirmed their ability to inhibit or reduce growth of the three Phytophthora species in a 96 well bioassay. Bacillus sp and Bacillus cereus were able to inhibit Phytophthora spp by 95 to 100 % and Micrococcus spp was able to decrease pathogen growth by 60 to 94 %. These bacterial isolates were further evaluated for plant growth promoting abilities on citrus rough lemon seedlings alone or in combination with arbuscular mycorrhizal inoculum. Bacterial and mycorrhizal inoculants influence the increase in shoot and root biomass. Bacillus cereus in combination with mycorrhizal inoculum significantly increased seedling shoot to root ratio while root biomass was significantly increased with mycorrhizal inoculation. Due to the short duration of the trial mycorrhizal colonisation could not be assessed. It is evident that selected combinations of bacteria and mycorrhizal fungi could promote citrus seedling growth and potentially improve seedling health. Further studies under nursery conditions are recommended.
- Full Text:
Investigations of growth metrics and δ15N values of water hyacinth (Eichhornia crassipes,(Mart.) Solms-Laub) in relation to biological control
- Authors: Hill, Jaclyn M
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444758 , vital:74265 , https://doi.org/10.1016/j.aquabot.2013.12.001
- Description: The success of biological control for Eichhornia crassipes (Mart) Solms-Laub has been varied, with failure attributed to various factors including increased eutrophication in freshwater systems. Studies have shown that high N-loads are associated with enriched δ15N values of aquatic biota. Stable isotope analyses may help to assess the nutrient status of invaded ecosystems and predict the success of classical biological control. A combination of controlled greenhouse experiments and in situ observations were used to quantify the δ15N equilibration rate of E. crassipes leaf tissue (i.e. the time span of the information on environmental N-loading), confirm the ability of plant tissue to reflect ecosystem N-loading and to compare standard water hyacinth growth metrics with δ15N and C/N ratios to evaluate how well they described eutrophication. Using both δ15N values and C/N ratios, it was possible to clearly distinguish between manure, fertilizer and control regimes and plant tissue provided information on ecosystem N loading over approximately 16 days.
- Full Text:
- Authors: Hill, Jaclyn M
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444758 , vital:74265 , https://doi.org/10.1016/j.aquabot.2013.12.001
- Description: The success of biological control for Eichhornia crassipes (Mart) Solms-Laub has been varied, with failure attributed to various factors including increased eutrophication in freshwater systems. Studies have shown that high N-loads are associated with enriched δ15N values of aquatic biota. Stable isotope analyses may help to assess the nutrient status of invaded ecosystems and predict the success of classical biological control. A combination of controlled greenhouse experiments and in situ observations were used to quantify the δ15N equilibration rate of E. crassipes leaf tissue (i.e. the time span of the information on environmental N-loading), confirm the ability of plant tissue to reflect ecosystem N-loading and to compare standard water hyacinth growth metrics with δ15N and C/N ratios to evaluate how well they described eutrophication. Using both δ15N values and C/N ratios, it was possible to clearly distinguish between manure, fertilizer and control regimes and plant tissue provided information on ecosystem N loading over approximately 16 days.
- Full Text:
Is economic growth without human development sustainable? : Sub-Saharan Africa’s recent growth acceleration in context
- Authors: Hadisi Basingene, Serge
- Date: 2014
- Subjects: Sustainable development -- Africa, Sub-Saharan , Economic development -- Africa, Sub-Saharan , Poverty -- Africa, Sub-Saharan , Africa, Sub-Saharan -- Social conditions , Africa, Sub-Saharan -- Economic conditions , Africa, Sub-Saharan -- Economic policy
- Language: English
- Type: Thesis , Masters , MEcon
- Identifier: vital:1098 , http://hdl.handle.net/10962/d1013137
- Description: The purpose of the study has been to assess the question of sustainability of economic growth and human development, particularly using sub-Saharan Africa in context. Sub-Saharan Africa is an interesting case study because, on the one hand, it has been mired in poverty and remains the least developed region in the world, and on the other, it has experienced a revival in economic growth since the mid-1990s. Economists tend to use the term economic development and economic growth interchangeably. However, questions have been raised about whether Africa’s latest growth episode is indeed ‘development’. Although there are many issues at stake, the key question, and the focus of this thesis, is whether sub-Saharan Africa’s revival is sustainable. The paper sets out the debate between the ‘World Bank view’ and the ‘alternative view’. The main debate lies around how genuine development should be achieved. Firstly, the ‘World Bank view’ claims that economic growth is necessary and sufficient condition to achieve development. Economic growth will be generated by ‘orthodox’ policies and this growth will automatically trickle-down and stimulate development. Secondly, the ‘alternative view’ argues that economic growth is necessary but it is not sufficient to stimulate sustainable development. Economic growth without ‘qualitative’ change is not ‘sustainable’. Indeed, human development shortfalls (as well as other, social, political and structural problems), if not addressed through appropriate policy interventions, can undermine economic growth. The ‘alternative view’ appears to be strongly supported by evidence from other developing regions such as Latin America and East Asia. The empirical study conducted in this thesis reinforces doubts about ‘sustainability’. Even though there are signs of convergence in some indicators; this is not the case for all indicators. More importantly the gap between sub-Saharan Africa and other developing regions remains very wide. Sub-Saharan Africa’s development path remains uncertain. The intention in this study is not to be conclusive that sub-Saharan Africa cannot achieve sustainable development. Rather the study attempts to identify potential hindrances to sub-Saharan Africa’s development and to provide a solid foundation for further research in the same direction.
- Full Text:
- Authors: Hadisi Basingene, Serge
- Date: 2014
- Subjects: Sustainable development -- Africa, Sub-Saharan , Economic development -- Africa, Sub-Saharan , Poverty -- Africa, Sub-Saharan , Africa, Sub-Saharan -- Social conditions , Africa, Sub-Saharan -- Economic conditions , Africa, Sub-Saharan -- Economic policy
- Language: English
- Type: Thesis , Masters , MEcon
- Identifier: vital:1098 , http://hdl.handle.net/10962/d1013137
- Description: The purpose of the study has been to assess the question of sustainability of economic growth and human development, particularly using sub-Saharan Africa in context. Sub-Saharan Africa is an interesting case study because, on the one hand, it has been mired in poverty and remains the least developed region in the world, and on the other, it has experienced a revival in economic growth since the mid-1990s. Economists tend to use the term economic development and economic growth interchangeably. However, questions have been raised about whether Africa’s latest growth episode is indeed ‘development’. Although there are many issues at stake, the key question, and the focus of this thesis, is whether sub-Saharan Africa’s revival is sustainable. The paper sets out the debate between the ‘World Bank view’ and the ‘alternative view’. The main debate lies around how genuine development should be achieved. Firstly, the ‘World Bank view’ claims that economic growth is necessary and sufficient condition to achieve development. Economic growth will be generated by ‘orthodox’ policies and this growth will automatically trickle-down and stimulate development. Secondly, the ‘alternative view’ argues that economic growth is necessary but it is not sufficient to stimulate sustainable development. Economic growth without ‘qualitative’ change is not ‘sustainable’. Indeed, human development shortfalls (as well as other, social, political and structural problems), if not addressed through appropriate policy interventions, can undermine economic growth. The ‘alternative view’ appears to be strongly supported by evidence from other developing regions such as Latin America and East Asia. The empirical study conducted in this thesis reinforces doubts about ‘sustainability’. Even though there are signs of convergence in some indicators; this is not the case for all indicators. More importantly the gap between sub-Saharan Africa and other developing regions remains very wide. Sub-Saharan Africa’s development path remains uncertain. The intention in this study is not to be conclusive that sub-Saharan Africa cannot achieve sustainable development. Rather the study attempts to identify potential hindrances to sub-Saharan Africa’s development and to provide a solid foundation for further research in the same direction.
- Full Text: