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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.
441

Assessing the suitability of antibiotic resistance markers and the indirect ELISA technique for studying the competitive ability of selected Cyclopia Vent. rhizobia under glasshouse and field conditions in South Africa

Spriggs, AC, Dakora, FD 20 July 2009 (has links)
Abstract Background: Symbiotic N2 fixation in legumes is constrained by many factors, including the paucity of suitable soil rhizobia To maximise growth of legume species therefore often requires the application of effective rhizobia as inoculants. But where native strains out-compete introduced rhizobia for nodule formation, it is important that the competitiveness of selected strains is tested in the field and glasshouse prior to their recommendation as commercial inoculants. However the methodology for strain identification inside nodules has often proved difficult and thus limited this field of research. In this study, the suitability of the antibiotic resistance technique (both intrinsic low-resistance fingerprinting and high-resistance marking) and the serological indirect ELISA method were assessed for their ability to detect selected Cyclopia rhizobia under glasshouse and field conditions. The four rhizobial strains that were used, namely PPRICI3, UCT40a, UCT44b and UCT61a, were isolated from wild Cyclopia species growing in the Western Cape fynbos of South Africa. Results: The test strains formed two distinct groups with regard to their intrinsic resistance to the antibiotics streptomycin sulphate and spectinomycin dihydrochloride pentahydrate, making it impossible to use intrinsic antibiotic resistance to distinguish strains from within the same intrinsic resistance group. The use of strains marked with double antibiotic resistance was also investigated. A number of these strains lost their antibiotic marker tags after one plant passage; and some also lost their competitive ability. The indirect ELISA technique provided a more satisfactory method of identifying selected Cyclopia strains under both field and glasshouse conditions. The primary antibodies raised against strains UCT40a, UCT61a and UCT44b gave absorbance readings that were unambiguously negative (0.30 OD405), while those of strain PPRICI3 were ambiguous (0.50 OD405) with many false positive readings (1.0 A405). The indirect ELISA method showed a high level of analytical sensitivity in glasshouse experiments and there were no cross-reactions between the four test strains. The method was also suitable for detecting three of the four test strains in competition studies under field conditions, and can also be used to identify some strains under field conditions. Conclusion: The antibiotic marker method was found unsuitable for identifying Cyclopia rhizobia in competition experiments in both glasshouse and field conditions. However, the indirect ELISA technique was found suitable for identifying these strains in glasshouse studies. The method was also appropriate for identifying strains UCT40a, UCT44b and UCT61a, but not strain PPRICI3, in field competition studies.
442

Optimization of base station placement for uneven traffic in cellular networks using genetic algorithms.

Philemon, B. R. January 2008 (has links)
M. Tech. Electrical Engineering. / Aims to optimize base station placement in a network area using multi-objective GAs to maximize coverage while minimizing cost. This well be done by considering varying traffic demand, interference between cells, availability of base station sites and taking into account different propagation environments i.e. urban, suburban and rural area.
443

A temporal analysis of trophy quality in South Africa: has trophy quality changed over time?

von Brandis, RG, Reilly, BK 27 February 2007 (has links)
Adatabase of approximately 9000 trophy measurements of ungulates hunted in South Africa between 1993 and 2001 was analysed in order to detect monotonic trends in trophy quality over time. In a species-specific analysis, declines were found for impala (Aepyceros melampus), springbok (Antidorcas marsupialis) and mountain reedbuck (Redunca fulvorufula). In an area-specific analysis, a decline was found in the Northern Cape Province. Conversely, blesbok (Damaliscus dorcas phillipsi ) (species-specific) and the Free State Province (area-specific) showed increases in trophy quality. As an economic indicator, the monitoring of trophy quality allows agencies to potentially evaluate the quality and sustainability of their ‘huntable’ ungulate resources.
444

Literature and law under apartheid

Way, Sarah Eleanor January 1999 (has links)
No description available.
445

Critical factors for service quality in the intercity bus transport industry

Pan, Qi January 2008 (has links)
Thesis (M.Tech.: Marketing)-Dept. of Marketing, Durban University of Technology, 2008. xiii, 135 leaves. / South Africa will host the Soccer World Cup in 2010. About 2.7 million local spectators and 400,000 visitors need to be transferred to and from the 10 host cities in 43 days. This is a huge challenge to the intercity bus transport industry, because the current transport system may not meet the demand for one of the world’s largest sporting event. The purpose of this study is to identify the current barriers to good service quality in the intercity bus transport industry. It focuses on the measurement of service quality and communication. In this research, the literature survey defined the service quality “gap” in this industry, identified the role of effective communication in the service delivery system, measured the variables affecting current service delivery using the SERVQUAL instrument, and prioritized the importance of the factors influencing service delivery in this industry. A questionnaire with 25 questions was designed to collect data. This study used convenience sampling to select 400 passengers as a sample, viz. 348 South Africans and 52 foreigners at the Durban bus station, since Durban is one of the ten host cities of the 2010 FIFA World Cup. The data was analysed using SPSS. The results of this research pointed to the importance of external communication in the industry. Specific recommendations are made to improve the productivity, reduce vacancy rate and maximize the benefits to this industry in 2010 and beyond.
446

Host specificity in South African mistletoes.

Okubamichael, Desale Yosief. January 2013 (has links)
Mistletoes intimately connect to their host trees with a haustorium that allows them to access nutrients and water. Mistletoes in South Africa vary greatly in their degree of host specificity. Most species occur on a wide range of host families, while others are restricted to a single host family or—at the extreme—to a single host species. Mistletoes that are host generalists at a larger spatial scale may become host-specific at a local scale. One of the challenges in mistletoe biology is determining the factors that maintain local host specificity. Birds potentially reinforce the mistletoe–host interactions by direct dispersal. However, many mistletoe species coexist while parasitising different co-occurring host species. This suggests that host trees may impose more selection pressure than birds in determining host specificity. Thus, my thesis examines the role of host trees as ecological and physiological filters that influence the infection patterns and determine host specificity of mistletoes in South Africa. The second chapter of this thesis synthesises the literature on host specificity in mistletoes. I then present the results of four field and laboratory experiments that were used examine the features affecting host specificity in representatives of two families of mistletoes (Loranthaceae and Viscaceae) in South Africa. My main research objectives focus on host abundance and morphology, host compatibility, host water and nutrient content, abiotic influences on mistletoe seedling survival and growth and mistletoe–host stomatal morphology in relation to water potential that affect nutrient acquisition by mistletoes from their host trees. The geographic mosaic approach was explored as a potential explanation for the mistletoe–host interactions that direct host specificity in mistletoes. I synthesised the available literature on the mechanisms and factors that direct mistletoe host specificity. This was supported by data analysed from South African herbarium collections, books describing the South African flora and field observations in South Africa. I suggest that host abundance (host availability through time and space) and host compatibility (as determined by genetic, morphological, physiological and chemical factors) play a primary role in determining host specificity in South African mistletoes, while differential bird dispersal strengthens or weakens mistletoe–host interactions. Analysis of the network structure of mistletoe–host interactions at different levels (e.g., at the level of population, species and genus) followed by genetic and reciprocal germination experiments may reveal the patterns and mechanisms of host specificity in mistletoes. I quantified the mistletoe–host composition, height of potential host trees and nutrient and water content of mistletoes and their hosts at Pniel Estates. Surveys of the study site revealed a single mistletoe species, Viscum rotundifolium, parasitising only Ziziphus mucronata and Ehretia rigida. Both parasitised host species were not the most abundant trees, were not the tallest trees and did not have the highest water or nutrient content of trees in the area, although these factors have been found to be good predictors for mistletoe parasitism in other studies. Subsequently, I tested mistletoe–host compatibility by conducting a germination experiment in the greenhouse by inculcating seeds of V. rotundifolium on freshly cut branches of nine available potential host trees. I found that mistletoe seeds had a greater chance of attachment and subsequent survival on branches of E. rigida and Z. mucronata as compared with seeds on co-occurring Acacia and other potential host species. This suggests that host compatibility plays a role in directing the host specificity of V. rotundifolium at Pniel Estates. I found that individuals of V. rotundifolium had more negative water potentials than their host trees and, by doing so, they passively maintain the flow of nutrients. In addition, I found evidence that the mistletoe uses active uptake to access nutrients from host phloem because the leaf tissue of a mistletoe had a nitrogen-to-calcium ratio (N:Ca) >1. Conventionally, a high N:Ca ratio (>1) in the leaf tissue of a mistletoe is taken as evidence of active uptake from host phloem because N is highly phloem-mobile while Ca is a large molecule and is phloem-immobile. This method has shortcomings discussed at greater length in the chapter but my findings suggest that the mistletoe V. rotundifolium uses a combination of passive and active nutrient uptake. I quantified the mistletoe–host community composition and host physical features (height and diameter at breast height) in two sites in KwaZulu-Natal, South Africa—Highover and Mtontwane. The mistletoe Agelanthus natalitius (Loranthaceae) is common at both sites, parasitising the most abundant host species—Acacia karroo—and the second most abundant host tree—Acacia caffra. Prevalence of mistletoe infection (percentage of trees parasitised) was positively correlated with tree size (height and diameter at breast height). The two host species did not differ significantly in height. At Highover the host species A. caffra and A. karroo had a similar prevalence of mistletoe infection but at Mtontwane a significantly higher percentage of A. caffra trees was parasitised in comparison with A. karroo. However, the intensity of mistletoe infection (mean number of mistletoes per tree) was lower for A. caffra (Highover: 0.66 ± 0.01, Mtontwane: 0.89 ± 0.04) than for A. karroo (Highover: 0.73 ± 0.04, Mtontwane: 1.03 ± 0.64). There were two highly infected big trees in Highover and one in Mtontwane where many mistletoe-dispersing birds were nesting which inflated the numbers for intensity of mistletoe infection in A. caffra, however. I tested mistletoe–host compatibility by conducting a reciprocal transplant experiment in the two study sites. I applied a paired design, using one local and one non-local mistletoe seed in each pair, with seed pairs placed on the two main host species at the different sites. Except in Highover where an unidentified pathogen retarded growth and survival, mistletoe seeds placed on the same substrate and in the same site as their source host grew a longer hypocotyl and had greater survival. Regardless of source, mistletoes placed on A. karroo had longer hypocotyls and greater survival than mistletoes on A. caffra. These results suggest that there may be adaptation of the mistletoe Agelanthus natalitius to the most frequently encountered host species, Acacia karroo. To simulate the conditions encountered by mistletoes during the dry and cold South African winter, mistletoe seedlings were monitored at different levels of microclimate (light, temperature and moisture) in a growth chamber. I found that higher light availability (20% and 40% shade versus 80% shade), cool temperatures (15°C and 20°C versus 25°C) and continuous moisture availability improved seedling development and subsequent survival of two mistletoe species (Viscum rotundifolium and Agelanthus natalitius). I studied the leaf stomata of two host–mistletoe pairs (Acacia karroo–Agelanthus natalitius and Vitex obovata–Erianthemum dregei) using a scanning electron microscope to investigate some of the underlying mechanisms that enable mistletoes to maintain more negative water potentials than their host trees and at the same time control water loss. In addition, I examined the response of mistletoes to the application of abscisic acid (ABA), a plant growth regulator that controls stomatal closure. I found that the mistletoes had a higher density of stomata and had larger stomata than their host trees. In addition, both mistletoe and host leaves closed their stomata during midday and in response to exogenous ABA. The ability of mistletoes to control water loss in this way may be one reason why mistletoes rarely kill their host trees, which would be maladaptive. The mistletoes used in my studies are known to be host generalists at a larger spatial scale but I found that they were host specific at a local scale. The results of my research suggest that host abundance and compatibility play a role in directing host specificity, while host nutrient and water status have little effect on host specificity at this local scale. The interactions between the generalist mistletoes used in my studies and their hosts are likely to vary over the geographic ranges of the mistletoe and alternate among different hosts. This may create multiple locally host–specific mistletoe populations and produce a complex geographic mosaic of mistletoe–host combinations across space and time. I suggest that mistletoe populations in South Africa may comprise numerous lineages incapable of parasitising the full range of host species, which could potentially lead to the formation of distinct host races over time. In the future, it would be interesting to document the infection patterns of these generalist mistletoe species across their entire geographic ranges in southern Africa, with particular focus on the patterns of mistletoe infection in places where the host abundance changes among sites. Host preferences may vary with changes in host frequency and host community composition. This could be paired with reciprocal transplant germination experiments in several sites to ascertain whether the mistletoe species have higher fitness on the most locally abundant hosts. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.
447

An examination of homicide statistics in South Africa (1948-2003) using a Durkheim analysis of anomie.

January 2007 (has links)
This work provides a statistical analysis and interpretation of homicide rates and patterns in South Africa for the years 1948 to 2003. Complied from data accessed from the South African Police Services, Mortuary Reports, the Truth and Reconciliation Commission and Non Government Organisations the patterns of homicide according to race, gender and age are analysed. This thesis proposes that the anomic condition of South African society is a key contributor to the creation and maintenance of the high levels of homicide found in this society. The normalisation of inter-personal violence through the collective conscious of communities and individuals has resulted in the growth of homicide and its continued high levels ten years after the end of Apartheid. This hypothesis is further supported through a survey conducted upon teenage subjects in Kwa-Zulu Natal province of their attitudes towards the use of violence. This work demonstrated strong positive support for interpersonal violence by members of the police and state. The survey also showed significant racial and gender differences in attitudes. The anomic conditions that continue to be present in South Africa will contribute to the weakness of the criminal justice system, and the willingness of individuals and communities to use their own resources to combat crime rather than rely upon the state and its agents for protection. The result being a continued high level of violence and a weak criminal justice system. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.
448

Paperclay in recent South African ceramics : continuity and change in studio works.

Frisinger, Leanne April. January 2012 (has links)
This dissertation comprises the documentation and theoretical component of a practice-led Master of Arts in Fine Art. The illustrated text focuses in four chapters on a critical explication of contemporary South African ceramists namely, Juliet Armstrong, Betsy Nield, Liza Firer and Leanne Frisinger. The dissertation includes significant discoveries about the creative use of paperclay in contemporary South African ceramics and provides documentary record of the candidate’s materials and processes. A conclusion briefly compares productions referred to in the text. / Thesis (M.A.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.
449

The religious identity of the church and its social and political mission in South Africa 1948-1984 : a historical and theological analysis

Baai, Gladstone Sandi January 1988 (has links)
This study is concerned with the identity of the Church and its social and political mission in South Africa. Here the argument is that the religious identity of the Church is fulfilled in the realization of the Kingdom of God through the historical event of incarnation which liberates human identity from oppression and alienation. This doctrine in turn, it is contended, depends for its relevance upon the significance of the concepts of prolepsis and commitment for the mission of the Church, Prolepsis signifies that the Church exists to bear witness to that which has come and is coming in Jesus Christ, In this way the thesis attempts to situate the proclamation of the Kingdom of God in relation to a particular problem of oppression and exploitation in South Africa, Hence commitment should be understood as the fulfilment of Black identity and thus as a liberation which brings about the transformation of the South African identity as a whole. In this thesis the hermeneutic circle as a theory of interpretation is applied in the theological and historical analysis of the South African social formation. Part One of the thesis lays the theoretical foundations of the study by developing the hypothesis and discussing identity theories and methodology. Part Two contains an analysis of South African social reality in which the variable of class is identified as that which underpins the South African social structure. Consequently, Apartheid is explained with reference to the economy rather than race. It is an economic rather than a racial factor. Part Three consists of a theological and sociological analysis of South Africa; it employs the Marxist social theory of alienation and applies the conception of identity advocated by the Liberation Movements of Southern Africa, particularly the African National Congress. It is concluded that the religious identity is a crucial factor in the emergence of a full humanity.
450

Vegetation and flora of the Transvaal

Burtt-Davy, Joseph January 1924 (has links)
No description available.

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