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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Limnoecology of the freshwater algal genera (excluding diatoms) on Marion Island (sub-Antarctic) / Wilma van Staden.

Van Staden, Wilma January 2011 (has links)
The aim of this study was to identify the algal genera found in the different freshwater bodies on Marion Island, to relate the presence or absence of the genera to the chemistry of the water bodies and to group the genera according to their limno-chemical preferences. The Island's freshwater algal genera were also compared with genera found on other Southern Ocean islands. The major factors influencing the chemical composition of the freshwaters of the island are the surrounding ocean and the manuring of seals and seabirds. The Western and Southern lakelets and wallows had higher mean conductivity values than most of the other water bodies. Eastern Inland lakelets, crater lakes and glacial lakes had low ion and nutrient concentrations, since they are mainly situated inland, away from bird or seal colonies. The chemical composition of wallows was influenced by manuring of seals and seabirds. The freshwaters are acidic and lakelets tend to be more acidic than glacial lakes. The lentic waters were more acidic than the stream. In total, 106 genera, mainly belonging to Chlorophyta (60 genera; 56% of total) and Cyanophyta (29 genera; 27% of total), were found in the freshwaters on the island. Other algal divisions found were Chrysophyta (7 genera), Euglenophyta (4 genera), Pyrrophyta (2 genera) and Xanthophyta (4 genera). Mean number of genera per sample ranged from 8 (in wallows) to 16 (in Eastern Inland lakelets). Filamentous algae were present in all the samples. Abundant green algae were Cosmarium, Klebsormidium, Mougeotia and Oedogonium. The most common cyanobacteria were Lyngbya and Chroococcus. The filamentous yellow-green alga, Tribonema, was also common. There were distinct differences in the algal composition between the southern, western and northern lakelets and the lakelets on the eastern side of the island. Sixty percent of the algal genera were present in waters with low conductivity values. Trichodesmium, Sphaerocystis and Tolypothrix occurred in freshwater bodies with higher conductivity values. Variance analysis showed that 87 of the 106 genera were less likely to occur in nitrogen and phosphate containing waters. Chlamydomonas, Prasiola, Spirogyra Trachelomonas, Tribonema, Ulothrix and Xanthidium were among the genera commonly found in nitrogen and phosphate containing waters. Diversity (number of genera per sample) was negatively correlated with conductivity, PO4-P, NH4-N and NO3-N. Diversity declined significantly with increasing salinity and eutrophication. Genera likely to occur in acidic waters include Binuclearia, Chlamydomonas, Chroococcus, Cosmarium, Klebsormidium, Microspora, Oedogonium, Oocystis, Prasiola, Scenedesmus, Staurastrum, Stigeoclonium, Tetrastrum, Ulothrix, Lyngbya, Synura and Tribonema. Marion Island’s algal flora shows a high affinity with that of Îles Kerguelen and Crozet, both located in the same biogeographical province (South Indian Ocean Province) of the sub-Antarctic than Marion Island, and a lesser affinity with islands in other sub-Antarctic provinces. Algal genera were grouped according to their limno-chemistry preferences. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2012.
2

Limnoecology of the freshwater algal genera (excluding diatoms) on Marion Island (sub-Antarctic) / Wilma van Staden.

Van Staden, Wilma January 2011 (has links)
The aim of this study was to identify the algal genera found in the different freshwater bodies on Marion Island, to relate the presence or absence of the genera to the chemistry of the water bodies and to group the genera according to their limno-chemical preferences. The Island's freshwater algal genera were also compared with genera found on other Southern Ocean islands. The major factors influencing the chemical composition of the freshwaters of the island are the surrounding ocean and the manuring of seals and seabirds. The Western and Southern lakelets and wallows had higher mean conductivity values than most of the other water bodies. Eastern Inland lakelets, crater lakes and glacial lakes had low ion and nutrient concentrations, since they are mainly situated inland, away from bird or seal colonies. The chemical composition of wallows was influenced by manuring of seals and seabirds. The freshwaters are acidic and lakelets tend to be more acidic than glacial lakes. The lentic waters were more acidic than the stream. In total, 106 genera, mainly belonging to Chlorophyta (60 genera; 56% of total) and Cyanophyta (29 genera; 27% of total), were found in the freshwaters on the island. Other algal divisions found were Chrysophyta (7 genera), Euglenophyta (4 genera), Pyrrophyta (2 genera) and Xanthophyta (4 genera). Mean number of genera per sample ranged from 8 (in wallows) to 16 (in Eastern Inland lakelets). Filamentous algae were present in all the samples. Abundant green algae were Cosmarium, Klebsormidium, Mougeotia and Oedogonium. The most common cyanobacteria were Lyngbya and Chroococcus. The filamentous yellow-green alga, Tribonema, was also common. There were distinct differences in the algal composition between the southern, western and northern lakelets and the lakelets on the eastern side of the island. Sixty percent of the algal genera were present in waters with low conductivity values. Trichodesmium, Sphaerocystis and Tolypothrix occurred in freshwater bodies with higher conductivity values. Variance analysis showed that 87 of the 106 genera were less likely to occur in nitrogen and phosphate containing waters. Chlamydomonas, Prasiola, Spirogyra Trachelomonas, Tribonema, Ulothrix and Xanthidium were among the genera commonly found in nitrogen and phosphate containing waters. Diversity (number of genera per sample) was negatively correlated with conductivity, PO4-P, NH4-N and NO3-N. Diversity declined significantly with increasing salinity and eutrophication. Genera likely to occur in acidic waters include Binuclearia, Chlamydomonas, Chroococcus, Cosmarium, Klebsormidium, Microspora, Oedogonium, Oocystis, Prasiola, Scenedesmus, Staurastrum, Stigeoclonium, Tetrastrum, Ulothrix, Lyngbya, Synura and Tribonema. Marion Island’s algal flora shows a high affinity with that of Îles Kerguelen and Crozet, both located in the same biogeographical province (South Indian Ocean Province) of the sub-Antarctic than Marion Island, and a lesser affinity with islands in other sub-Antarctic provinces. Algal genera were grouped according to their limno-chemistry preferences. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2012.
3

Simulation of tropical cyclone-like vortices over the southwestern Indian Ocean

Mbedzi, Maluta Pennington 25 October 2010 (has links)
Tropical cyclones claim a huge number of lives and cause substantial damage to property and crops in many regions each year. Southern Africa is no exception. This makes the process of forecasting tropical cyclones of great importance to the region’s economy and to public safety. Skillful seasonal forecasts of tropical cyclone activity could be used to warn the communities affected by tropical cyclones of the likely occurrence of such systems ahead of the cyclone season. This could result in reduced damage and fatalities associated with such systems. Both statistical and dynamical techniques have been employed in an attempt to predict tropical cyclone activity on a seasonal time scale over a number of ocean basins. The skills of such techniques vary from one technique to another and from one basin to another. This study investigates the predictability of tropical cyclone activity on a seasonal time scale over the southwestern Indian Ocean (SWIO) by nesting a regional climate model (RCM), the RegCM3 within a coarse-resolution atmospheric general circulation model (AGCM), the ECHAM4.5. The national meteorological centres of most southern African countries do not have the required dedicated computational resources to run the high-resolution GCMs that are suitable to predict these systems operationally. However, these systems can be very devastating on the southern African region and need to be predicted on various time scales, including the seasonal time scale. Therefore, it is instructive that research be done to better our understanding of these systems and their predictability using physical models. This study examines the simulations of the genesis locations and the number of tropical cyclones produced in RCM integrations nested within an AGCM forced by observed sea-surface temperatures (SSTs). The season of interest is the mid-summer period of December to February. Four members of the AGCM generated at the International Research Institute for Climate and Society (IRI) are used to force the RCM. Four-month integrations over a 10-year period (1991/92-2000/01) are performed. An objective procedure for detecting model-generated tropical cyclones is applied to this ensemble. Some characteristics of the simulated cyclones are compared with the observations. In addition, some statistical techniques are employed to evaluate the capability of the RCM to reproduce some aspects of the observed tropical cyclones during the aforementioned period. The results show that there is a good agreement between two of the simulated and observed environmental variables that influence tropical cyclone formation, viz. vertical wind shear and relative vorticity. In particular, the simulated and observed vertical wind shear show a similar pattern in most parts of the model domain. With regards to the relative vorticity, the highest agreement is found in the Mozambique Channel and in the region east of Madagascar. In addition, there is an appreciable agreement between the simulated and observed tropical cyclone characteristics such as tropical cyclone genesis locations and frequency. The model also simulated the interannual variability in the tropical cyclone frequency skillfully. AFRIKAANS : Tropiese siklone is verantwoordelik vir ‘n goot aantal sterftes en veroorsaak beduidende skade aan eindom asook oeste oor etlike areas elke jaar. Suidelike Afrika is nie ‘n uitsondering nie. Hierdie verliese maak die voorspelling van tropiese siklone van groot belang vir die gebied se ekonomie asook vir publieke veiligheid. Vaardige seisoenale voorspelling van tropiese sikloon aktiwiteit kan gebruik word om gemeenskappe wat onderhewig is aan die invloed van tropiese siklone te waarsku oor die kans vir sulke sisteme om voor te kom voordat die tropiese sikloon seisoen ‘n aanvang neem. Vroegtydige waarskuwings kan tot gevolg hê dat daar minder verwant skade en laer sterftes is. Beide statistiese en dinamiese tegnieke is al in die verlede gebruik om tropiese sikloon aktiwiteit oor verskeie oseaankomme op ‘n seisoenale tydskaal te probeer voorspel. Die vaardigheid van hierdie tegnieke hang af van die tipe tegniek wat gebruik word asook watter oseaankom beskou word. Hierdie studie ondersoek die voorspelbaarheid van tropies sikloon aktiwiteit op ‘n seisoenale tydskaal oor die suid-westelike Indiese Oseaan deur gebruik te maak van ‘n streeksmodel, die RegCM3, genes in ‘n growwe-resolusie algemene sirkulasie model van die atmosfeer, die ECHAM4.5. Die nasionale weerdienste van die meerderheid Suider-Afrikaanse lande beskik nie oor die nodige rekenaars om geskikte hoë-resolusie algemene sirkulasie modelle te loop om sodanige sisteme mee operasioneel te voorspel nie. Desnieteenstaande kan hierdie tropiese sisteme verwoestend wees en daarom behoort hulle voorspel te word op verskeie tydskale, insluitende seisoenale tydskale. Dit sal dus insiggewend wees om navorsing te doen om sodoende ons begrip oor hierdie sisteme en hul voorspelbaarheid te verbeter deur gebruik te maak van fisiese modelle. Hierdie studie gaan ondersoek instel oor die simulasie van tropiese siklone oor hul ontwikkelingsgebiede en die aantal tropiese siklone wat ‘n streeksmodel, genes in ‘n algemen sirkulasie model van die atmosfeer wat geforseer word deur waargeneemde see-oppervlak temperature, kan produseer. Die seisoen van belang is die mid-somer periode van Desember tot Februarie. Vier ensemble lede afkomstig vanaf die algemene sirkulasie model wat geloop is by die International Research Institute for Climate and Society word gebruik om die streeksmodel mee te forseer. Model integrasies word oor ‘n 4-maand periode gedoen en vir ‘n 10-jaar tydperk (1991/92-2000/01). ‘n Objektiewe vorteks opsporingsprosedure word dan toegepas op die 4-lid ensemble om model-geskepte tropiese siklone te identifiseer. Sommige van die karakteristieke van die gesimuleerde siklone word dan vergelyk met die waargeneemde tropiese stelsels. Hiermee saam word statisiese tegnieke ingespan vir die genoemde tydperk om die vermoë van die streeksmodel te ondersoek om sekere aspekte van waargeneemde storms te herproduseer. Die resultate wys dat daar ‘n goeie ooreenkoms is tussen twee van die gesimuleerde en waargeneemde omgewingsveranderlikes wat tropiese sikloon ontwikkeling beinvloed, nl, vertikale windskuiwing en relatiewe vortisiteit. In besonder het die gesimuleerde en waargeneemde vertikale windskuiwing ooreenstemmende patrone gelewer oor die grootste gedeelte van die streeks model-area. Wat relatiewe vortisiteit betref, is die beste ooreenkoms oor die Mosambiek kanaal en in die gebied oos van Madagaskar gevind. Verder is daar ‘n sterk ooreenkoms tussen die gesimuleerde en waargeneemde tropiese sikloon karakteristieke soos by die tropiese siklone se ontwikkelingsgebiede asook hul frekwensie. Die model he took daarin geslaag om die inter-jaarlikse veranderlikheid van tropiese sikloon frekwensie suksesvol te simuleer. / Dissertation (MSc)--University of Pretoria, 2010. / Geography, Geoinformatics and Meteorology / MSc / Unrestricted
4

Profiling the determinants of Indian foreign direct investment in Africa / Susanna Elizabeth Cloete

Cloete, Susanna Elizabeth January 2013 (has links)
India is fast becoming one of the largest economies worldwide, with expectations of becoming the second largest economy by 2050. The growth this country is demonstrating is accompanied by integration with other economies with active engagement in trade and investment in the world economy. Analysts and researchers strive to understand the possible effects of the rise of India on the global economy. The influence of India’s rise on Africa is an arguable topic. The Indo-Africa relationship has a strong political and socio-economic history. This relationship has undergone some changes since 1990 when India started a new approach that included internationalisation. In the modern economy the trade and investment from India to Africa have illustrated fast growth rates. It is claimed that India’s main interest in Africa is to gain access to Africa’s abundant resources with the intention of supporting its economic growth. This creates some concern on the nature of India’s involvement in Africa; whether or not it will increase the development and whether it will put pressure on Africa’s control of its resources. This study focuses on understanding the extent of Indian FDI in Africa and the factors that determine this involvement. Africa is known as the poorest continent worldwide; hence the development should be managed and controlled in order to sustain the growth. The flows of FDI to this continent can provide some advantages that include growth and development, while FDI can also prompt some disadvantages such as resource extraction. Profiling the determinants of Indian FDI in Africa provides an understanding of the influence India may have on Africa. Profiling the determinants of Indian FDI in Africa is done by means of a literature study that identifies the determinants that are applicable to African FDI. These determinants include natural resources, market size, political instability, macro-economic instability, weak policies, inflation, good governance, investment, GDP, growth, openness and oil production. Following the literature study an analysis is done on the trend of FDI worldwide and especially between India and Africa. The overall amount of FDI flows illustrates large increases globally and developed regions account for the majority of FDI flows. The trends of flows illustrate some changes that highlight the prominent role developing countries are starting to play. Africa is classified as a developing region that accounts for a fairly small amount of the total flows to the developing regions. It is noted that Africa’s share is steadily increasing and is expected to keep on rising. Indian FDI to Africa has demonstrated some staggering increases, while India claims to further increase its involvement. India’s FDI mainly flows to the resource sectors such as oil, coal and gas. India also states to expand its FDI involvement into African sectors such as the infrastructure, information technology, computer software, services and telecommunication. Identifying the specific determinants of Indian FDI in Africa is established by estimating models using the Structural Equation Method (SEMs). A combination of a factor analysis and regression analysis is estimated. The specific determinants that influence Indian FDI in Africa include government effectiveness, control of corruption, crude oil price, school enrolment and exports. The level or value of the investments is influenced by the government effectiveness and rule of law. This study concludes that India’s involvement in Africa is increasing. India demonstrates high levels of interest in Africa’s resources, but this is prone to expand across different sectors. / MCom (International Trade), North-West University, Potchefstroom Campus, 2013
5

Profiling the determinants of Indian foreign direct investment in Africa / Susanna Elizabeth Cloete

Cloete, Susanna Elizabeth January 2013 (has links)
India is fast becoming one of the largest economies worldwide, with expectations of becoming the second largest economy by 2050. The growth this country is demonstrating is accompanied by integration with other economies with active engagement in trade and investment in the world economy. Analysts and researchers strive to understand the possible effects of the rise of India on the global economy. The influence of India’s rise on Africa is an arguable topic. The Indo-Africa relationship has a strong political and socio-economic history. This relationship has undergone some changes since 1990 when India started a new approach that included internationalisation. In the modern economy the trade and investment from India to Africa have illustrated fast growth rates. It is claimed that India’s main interest in Africa is to gain access to Africa’s abundant resources with the intention of supporting its economic growth. This creates some concern on the nature of India’s involvement in Africa; whether or not it will increase the development and whether it will put pressure on Africa’s control of its resources. This study focuses on understanding the extent of Indian FDI in Africa and the factors that determine this involvement. Africa is known as the poorest continent worldwide; hence the development should be managed and controlled in order to sustain the growth. The flows of FDI to this continent can provide some advantages that include growth and development, while FDI can also prompt some disadvantages such as resource extraction. Profiling the determinants of Indian FDI in Africa provides an understanding of the influence India may have on Africa. Profiling the determinants of Indian FDI in Africa is done by means of a literature study that identifies the determinants that are applicable to African FDI. These determinants include natural resources, market size, political instability, macro-economic instability, weak policies, inflation, good governance, investment, GDP, growth, openness and oil production. Following the literature study an analysis is done on the trend of FDI worldwide and especially between India and Africa. The overall amount of FDI flows illustrates large increases globally and developed regions account for the majority of FDI flows. The trends of flows illustrate some changes that highlight the prominent role developing countries are starting to play. Africa is classified as a developing region that accounts for a fairly small amount of the total flows to the developing regions. It is noted that Africa’s share is steadily increasing and is expected to keep on rising. Indian FDI to Africa has demonstrated some staggering increases, while India claims to further increase its involvement. India’s FDI mainly flows to the resource sectors such as oil, coal and gas. India also states to expand its FDI involvement into African sectors such as the infrastructure, information technology, computer software, services and telecommunication. Identifying the specific determinants of Indian FDI in Africa is established by estimating models using the Structural Equation Method (SEMs). A combination of a factor analysis and regression analysis is estimated. The specific determinants that influence Indian FDI in Africa include government effectiveness, control of corruption, crude oil price, school enrolment and exports. The level or value of the investments is influenced by the government effectiveness and rule of law. This study concludes that India’s involvement in Africa is increasing. India demonstrates high levels of interest in Africa’s resources, but this is prone to expand across different sectors. / MCom (International Trade), North-West University, Potchefstroom Campus, 2013

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