The development of biological tools to aid in the genetic investigation of the black (Diceros bicornis) and white (Ceratotherium simum) rhinoceros mitochondrial genomes
- Authors: Parsons, Michelle
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/56059 , vital:26769
- Description: The black (Diceros bicornis) and white (Ceratotherium simum) rhinoceros are found in South Africa. A decline in the populations of these species has resulted due to human activities such as habitat fragmentation and poaching. This has contributed to the loss of genetic diversity amongst the black and white rhinoceros. Conservation and anti-poaching efforts are needed to help maintain genetic diversity. These efforts could be improved through the development of non-invasive techniques to examine DNA from threatened animals. The aim of this research was to develop a molecular technique which would allow for the identification of the black and white rhinoceros and to develop a molecular technique which would allow for intraspecies genetic variation to be examined. DNA extractions were performed on matched faecal and tissue samples that were collected from two regions in South Africa. Polymerase chain reaction (PCR) primer sets were designed to investigate several regions of the rhinoceros mitochondrial genome. PCR optimisation was completed for the target regions. Sequencing was conducted on all final PCR products. The cytochrome c oxidase subunit 1 (COIi) gene allowed for the rhinoceros family to be identified. This region was digested with the HindIII restriction enzyme, which allowed for the specific identification of either the black or white rhinoceros. A subsequent region of the cytochrome c oxidase subunit 1 (COIii) as well as the D-loop, hypervariable regions (HV1 and HV2), cytochrome b (cytb) and 16s rRNA regions were investigated. These regions displayed potential for establishing geographic origin for black rhinoceros samples, whereas the D-loop and HV2 show potential for the white rhinoceros. The white rhinoceros displayed sequence variation in the HV2 and cytb region, while variation was observed in the COIi and HV1 for the black rhinoceros. All investigated target regions allowed for the rhinoceros family to be identified. The COI (COIi and COIii), HV2 and cytb regions allowed for the subspecies of rhinoceros to be identified, however the D-loop was not able to identify the white rhinoceros species. The 16s rRNA and HV1 regions allowed for the correct subspecies of rhinoceros to be identified, however as the primers were only compatible for the black rhinoceros therefore a subsequent investigation is required for the white rhinoceros. The establishment of this novel PCR based technique to identify white and black rhinoceros will allow for efficient species identification in wildlife forensic cases. A biological method was established to study intraspecies variation for the white and black rhinoceros; however the investigated target regions did not yield sufficient genetic variation. The core techniques developed in this study will be valuable for future studies that wish to investigate genetic variation in mammal species.
- Full Text:
- Date Issued: 2015
- Authors: Parsons, Michelle
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/56059 , vital:26769
- Description: The black (Diceros bicornis) and white (Ceratotherium simum) rhinoceros are found in South Africa. A decline in the populations of these species has resulted due to human activities such as habitat fragmentation and poaching. This has contributed to the loss of genetic diversity amongst the black and white rhinoceros. Conservation and anti-poaching efforts are needed to help maintain genetic diversity. These efforts could be improved through the development of non-invasive techniques to examine DNA from threatened animals. The aim of this research was to develop a molecular technique which would allow for the identification of the black and white rhinoceros and to develop a molecular technique which would allow for intraspecies genetic variation to be examined. DNA extractions were performed on matched faecal and tissue samples that were collected from two regions in South Africa. Polymerase chain reaction (PCR) primer sets were designed to investigate several regions of the rhinoceros mitochondrial genome. PCR optimisation was completed for the target regions. Sequencing was conducted on all final PCR products. The cytochrome c oxidase subunit 1 (COIi) gene allowed for the rhinoceros family to be identified. This region was digested with the HindIII restriction enzyme, which allowed for the specific identification of either the black or white rhinoceros. A subsequent region of the cytochrome c oxidase subunit 1 (COIii) as well as the D-loop, hypervariable regions (HV1 and HV2), cytochrome b (cytb) and 16s rRNA regions were investigated. These regions displayed potential for establishing geographic origin for black rhinoceros samples, whereas the D-loop and HV2 show potential for the white rhinoceros. The white rhinoceros displayed sequence variation in the HV2 and cytb region, while variation was observed in the COIi and HV1 for the black rhinoceros. All investigated target regions allowed for the rhinoceros family to be identified. The COI (COIi and COIii), HV2 and cytb regions allowed for the subspecies of rhinoceros to be identified, however the D-loop was not able to identify the white rhinoceros species. The 16s rRNA and HV1 regions allowed for the correct subspecies of rhinoceros to be identified, however as the primers were only compatible for the black rhinoceros therefore a subsequent investigation is required for the white rhinoceros. The establishment of this novel PCR based technique to identify white and black rhinoceros will allow for efficient species identification in wildlife forensic cases. A biological method was established to study intraspecies variation for the white and black rhinoceros; however the investigated target regions did not yield sufficient genetic variation. The core techniques developed in this study will be valuable for future studies that wish to investigate genetic variation in mammal species.
- Full Text:
- Date Issued: 2015
Inspection of telegraph line
- Authors: McKay, G. , Brownlee, C.
- Date: 1868
- Language: English
- Type: cartographic
- Identifier: http://hdl.handle.net/10962/105127 , vital:32467
- Description: Inspection of telegraph line - G. McKay, East London to Potsdam - C. Brownlee, King Williams Town to Potsdam; [comp. by G. McKay?].Scale not stated. 1 sheet 14½" x 22". Manuscript; may be dated "1868".
- Full Text: false
- Authors: McKay, G. , Brownlee, C.
- Date: 1868
- Language: English
- Type: cartographic
- Identifier: http://hdl.handle.net/10962/105127 , vital:32467
- Description: Inspection of telegraph line - G. McKay, East London to Potsdam - C. Brownlee, King Williams Town to Potsdam; [comp. by G. McKay?].Scale not stated. 1 sheet 14½" x 22". Manuscript; may be dated "1868".
- Full Text: false
On the Wiener index of bicyclic graphs and graphs with fixed segment sequence
- Authors: Xhanti, Sinoxolo
- Date: 2021-10-29
- Subjects: Graph theory , Chemistry Mathematics , Chemistry Graphic methods , Wiener index , Bicyclic graphs , Fixed segment sequence , Degree sequence , Circumference , Core
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190700 , vital:45019
- Description: Wiener index is defined as the sum of the distances between all unordered pairs of vertices in a graph. The study of the Wiener index is motivated by its application in chemistry. This thesis focuses on finding extremal bicyclic graphs relative to Wiener index under various conditions such as fixed circumference (length of the longest cycle) or fixed size of the core (maximal subgraph with no degree less than 2). A segment of a graph G is either a path whose end vertices have degree 1 or at least 3 in G and all the internal vertices have degree 2 in G, or a cycle where all the vertices have degree 2 in G except possibly one. The lengths of all the segments of G form it segment sequence. We also discuss extremal graphs with given segment sequence. , Thesis (MSc) -- Faculty of Science, Mathematics, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Xhanti, Sinoxolo
- Date: 2021-10-29
- Subjects: Graph theory , Chemistry Mathematics , Chemistry Graphic methods , Wiener index , Bicyclic graphs , Fixed segment sequence , Degree sequence , Circumference , Core
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190700 , vital:45019
- Description: Wiener index is defined as the sum of the distances between all unordered pairs of vertices in a graph. The study of the Wiener index is motivated by its application in chemistry. This thesis focuses on finding extremal bicyclic graphs relative to Wiener index under various conditions such as fixed circumference (length of the longest cycle) or fixed size of the core (maximal subgraph with no degree less than 2). A segment of a graph G is either a path whose end vertices have degree 1 or at least 3 in G and all the internal vertices have degree 2 in G, or a cycle where all the vertices have degree 2 in G except possibly one. The lengths of all the segments of G form it segment sequence. We also discuss extremal graphs with given segment sequence. , Thesis (MSc) -- Faculty of Science, Mathematics, 2021
- Full Text:
- Date Issued: 2021-10-29
Investigation into response of wheat genotypes to drought and optimum conditions in the Eastern Cape Province, South Africa
- Authors: Mzileni L S
- Date: 2023
- Subjects: Bonanza farms , Wheat , Drought - tolerant plants
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27732 , vital:69397
- Description: Wheat is generally one of the dominant crops globally, being mainly used for human food and livestock feed. Due to climate change, drought makes it challenging to produce enough wheat mostly under dryland production regions in South Africa. Drought stress has severely reduced wheat yield by up to 70 percent, and adversely compromised wheat grain quality. The adoption of drought-tolerant cultivars offers a sustainable and low-cost solution for increasing wheat yields and minimise importing the crop to meet national requirements. The main objective of this study was to investigate the response of different wheat genotypes to drought and optimum conditions in the Eastern Cape Province, South Africa. Forty diverse wheat genotypes were evaluated in this study. The specific objectives were: (i) to evaluate the response of wheat genotypes under optimum and drought-stressed field conditions; (ii) to determine the effect of terminal drought stress on wheat grain quality composition; and (iii) to identify appropriate drought tolerance indices that can be used as selection tools under field conditions. This study was conducted in the field using a 5x8 alpha lattice design, replicated twice under two water regimes (drought and optimum) over two consecutive winter seasons of 2020 and 2021 at two different sites namely University of Fort Hare Research Farm in Alice, and Zanyokwe irrigation scheme in Keiskamahoek. Drought stress was imposed from 50% flowering up to physiological maturity. Data on agro-physiological traits such as duration to heading (DTH); flowering (DTF); maturity (DTM); plant height (HT); spike length (SL); number of spikelets per spike (SPS); kernels per spike (KPS); and grain yield (GY (kg/ha)) was subjected to the analysis of variance using Genstat 18th edition. As the study took place over two sites, a combined ANOVA table revealed significant differences (p0.001) among genotypes, and all interactions such as genotype by water regime (GWR); genotype by seasons (GS) for all studied traits. Notably, the extent and severity of drought differed between geographical regions and between seasons. This necessitated the adoption of the additive main effect and multiplicative interaction analysis (AMMI) for the identification of stable genotypes under two different water regimes over two sites. Regarding grain yield, superior and/or stable genotypes included G5 (4334 kg/ha under optimum, and 2871kg/ha under drought), and G22 (4418 kg/ha under optimum, and 2624kg/ha under drought) at the UFH site. G21 (3194 kg/ha under optimum, and 2938 kg/ha under drought), G33 (2552kg/ha under optimum, and 3810 kg/ha under drought), and G35 (2688 kg/ha under optimum, and 3309 kg/ha under drought) at the ZAN site. Stable genotypes across sites included G21 and G33. There were generally weak correlations between agro-physiological traits and grain yield. From the experiment, grain quality traits such as fixed protein (PF); wet gluten (WG); hectolitre mass (HLM); and thousand kernel weight (TKW) were also examined. A combined ANOVA revealed significant differences (p0.001) among the interaction of genotypes by environments (GE) for all traits except PF. This implies that the performance of wheat genotypes across sites was also different, and therefore, necessitated separate analysis of variance for each site. Significant differences (p0.001) among genotypes (G), water regimes (WR), and the interaction of genotypes by water regime (GWR) were observed for all studied quality traits except PF in both sites. GWR showed no significant differences for TKW in the ZAN site. The stability in the performance of genotypes across water regimes was further determined. G38 was stable for wet gluten; G31 and G26 were stable for PF; G36 was stable for HLM; and G11, G15, and G29 were stable for TKW at the UFH site. G6 was stable for both WG and PF; G13 and G15 were stable for HLM; and G35, G21, and G40 were stable for TKW at the ZAN site. These results suggest that the quality of wheat grains was affected under drought stress conditions except PF. Average grain yield data under both stressed (Ys) and optimum (Yp) conditions was used to compute a number of different drought tolerance indices. These include mean productivity (MP); geometric mean productivity (GMP); harmonic mean (HM); Tolerance index (TOL), stress susceptible index (SSI), sensitive drought index (SDI), and stress tolerance index (STI). The aim was to identify appropriate drought tolerance indices that can be used as selection tools under drought stress. MP, GMP, and HM were the more appropriate indices as they had a strong and positive correlation with grain yield under both drought and optimum conditions. However, genotypes G5, G22, G8, and G21 were more tolerant and stable as they showed high mean values. Based on the results, G19, G16, G2, and G20 were more sensitive to drought as they showed low values of MP, GMP, and HM. Overall, genotype: G5, G21, G22, and G33 are recommended for production under drought and optimum conditions, as they showed stable performance across water regimes. Principal component analysis also revealed that MP, GMP, and HM were the only indices that had positive loadings into the first principal component. , Thesis (MSc) -- Faculty of Science and Agriculture, 2023
- Full Text:
- Date Issued: 2023
- Authors: Mzileni L S
- Date: 2023
- Subjects: Bonanza farms , Wheat , Drought - tolerant plants
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27732 , vital:69397
- Description: Wheat is generally one of the dominant crops globally, being mainly used for human food and livestock feed. Due to climate change, drought makes it challenging to produce enough wheat mostly under dryland production regions in South Africa. Drought stress has severely reduced wheat yield by up to 70 percent, and adversely compromised wheat grain quality. The adoption of drought-tolerant cultivars offers a sustainable and low-cost solution for increasing wheat yields and minimise importing the crop to meet national requirements. The main objective of this study was to investigate the response of different wheat genotypes to drought and optimum conditions in the Eastern Cape Province, South Africa. Forty diverse wheat genotypes were evaluated in this study. The specific objectives were: (i) to evaluate the response of wheat genotypes under optimum and drought-stressed field conditions; (ii) to determine the effect of terminal drought stress on wheat grain quality composition; and (iii) to identify appropriate drought tolerance indices that can be used as selection tools under field conditions. This study was conducted in the field using a 5x8 alpha lattice design, replicated twice under two water regimes (drought and optimum) over two consecutive winter seasons of 2020 and 2021 at two different sites namely University of Fort Hare Research Farm in Alice, and Zanyokwe irrigation scheme in Keiskamahoek. Drought stress was imposed from 50% flowering up to physiological maturity. Data on agro-physiological traits such as duration to heading (DTH); flowering (DTF); maturity (DTM); plant height (HT); spike length (SL); number of spikelets per spike (SPS); kernels per spike (KPS); and grain yield (GY (kg/ha)) was subjected to the analysis of variance using Genstat 18th edition. As the study took place over two sites, a combined ANOVA table revealed significant differences (p0.001) among genotypes, and all interactions such as genotype by water regime (GWR); genotype by seasons (GS) for all studied traits. Notably, the extent and severity of drought differed between geographical regions and between seasons. This necessitated the adoption of the additive main effect and multiplicative interaction analysis (AMMI) for the identification of stable genotypes under two different water regimes over two sites. Regarding grain yield, superior and/or stable genotypes included G5 (4334 kg/ha under optimum, and 2871kg/ha under drought), and G22 (4418 kg/ha under optimum, and 2624kg/ha under drought) at the UFH site. G21 (3194 kg/ha under optimum, and 2938 kg/ha under drought), G33 (2552kg/ha under optimum, and 3810 kg/ha under drought), and G35 (2688 kg/ha under optimum, and 3309 kg/ha under drought) at the ZAN site. Stable genotypes across sites included G21 and G33. There were generally weak correlations between agro-physiological traits and grain yield. From the experiment, grain quality traits such as fixed protein (PF); wet gluten (WG); hectolitre mass (HLM); and thousand kernel weight (TKW) were also examined. A combined ANOVA revealed significant differences (p0.001) among the interaction of genotypes by environments (GE) for all traits except PF. This implies that the performance of wheat genotypes across sites was also different, and therefore, necessitated separate analysis of variance for each site. Significant differences (p0.001) among genotypes (G), water regimes (WR), and the interaction of genotypes by water regime (GWR) were observed for all studied quality traits except PF in both sites. GWR showed no significant differences for TKW in the ZAN site. The stability in the performance of genotypes across water regimes was further determined. G38 was stable for wet gluten; G31 and G26 were stable for PF; G36 was stable for HLM; and G11, G15, and G29 were stable for TKW at the UFH site. G6 was stable for both WG and PF; G13 and G15 were stable for HLM; and G35, G21, and G40 were stable for TKW at the ZAN site. These results suggest that the quality of wheat grains was affected under drought stress conditions except PF. Average grain yield data under both stressed (Ys) and optimum (Yp) conditions was used to compute a number of different drought tolerance indices. These include mean productivity (MP); geometric mean productivity (GMP); harmonic mean (HM); Tolerance index (TOL), stress susceptible index (SSI), sensitive drought index (SDI), and stress tolerance index (STI). The aim was to identify appropriate drought tolerance indices that can be used as selection tools under drought stress. MP, GMP, and HM were the more appropriate indices as they had a strong and positive correlation with grain yield under both drought and optimum conditions. However, genotypes G5, G22, G8, and G21 were more tolerant and stable as they showed high mean values. Based on the results, G19, G16, G2, and G20 were more sensitive to drought as they showed low values of MP, GMP, and HM. Overall, genotype: G5, G21, G22, and G33 are recommended for production under drought and optimum conditions, as they showed stable performance across water regimes. Principal component analysis also revealed that MP, GMP, and HM were the only indices that had positive loadings into the first principal component. , Thesis (MSc) -- Faculty of Science and Agriculture, 2023
- Full Text:
- Date Issued: 2023
Equiprime near-rings
- Authors: Mogae, Kabelo
- Date: 2008
- Subjects: Near-rings
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10505 , http://hdl.handle.net/10948/1028 , Near-rings
- Description: Prior to 1990, the only well known ideal-hereditary Kurosh-Amitsur radicals in the variety of zero-symmetric near-rings were the Jacobson type radicals Iv(N) , where ∨∈{2,3} and the Brown-McCoy radical. In 1990, Booth, Groenewald and Veldsman introduced the concept of an equiprime near-ring which leads to an ideal-hereditary Kurosh-Amitsur radical in N∘. The concept of an equiprime near-ring generalizes the concept of a prime ring to near-rings. Although the search for more ideal-hereditary radicals of near-rings was apparently the original motivation for the introduction of equiprime near-rings, it became clear that these near-rings are interesting in their own right. It is our aim in this treatise to give an exposition of the many interesting properties of equiprime near-rings. We begin with a brief reminder of near-ring rudiments; giving basic definitions and elementary results which are necessary for understanding and development of subsequent chapters. With the basics out of the way, our main task begins with a consideration of equiprime, strongly and completely equiprime left ideals. It is noted that any zero-symmetric near-ring can be embedded in an equiprime near-ring. Moreover, the class of equiprime near-rings is shown to be hereditary. Open questions arising out of the study of equiprime near-rings are highlighted along the way. In Chapter 3 we consider well known examples of near-rings and determine when such near-rings are equiprime. This provides more insight into the nature of equiprime near-rings and is a fertile ground for the birth of examples and counterexamples which may be used to close or solve some open question within the literature. We also prove some results which generalize some results of Booth and Hall [10] and Veldsman [29]. These results have not been previously presented elsewhere to the best of our knowledge. vii In Chapter 4, the equiprime near-rings are shown to yield an ideal-hereditary radical in N∘. It is shown that a special radical theory can be built on the equiprime nearrings in much the same way prime rings are used in ring theory to define special radical classes of rings.
- Full Text:
- Date Issued: 2008
- Authors: Mogae, Kabelo
- Date: 2008
- Subjects: Near-rings
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10505 , http://hdl.handle.net/10948/1028 , Near-rings
- Description: Prior to 1990, the only well known ideal-hereditary Kurosh-Amitsur radicals in the variety of zero-symmetric near-rings were the Jacobson type radicals Iv(N) , where ∨∈{2,3} and the Brown-McCoy radical. In 1990, Booth, Groenewald and Veldsman introduced the concept of an equiprime near-ring which leads to an ideal-hereditary Kurosh-Amitsur radical in N∘. The concept of an equiprime near-ring generalizes the concept of a prime ring to near-rings. Although the search for more ideal-hereditary radicals of near-rings was apparently the original motivation for the introduction of equiprime near-rings, it became clear that these near-rings are interesting in their own right. It is our aim in this treatise to give an exposition of the many interesting properties of equiprime near-rings. We begin with a brief reminder of near-ring rudiments; giving basic definitions and elementary results which are necessary for understanding and development of subsequent chapters. With the basics out of the way, our main task begins with a consideration of equiprime, strongly and completely equiprime left ideals. It is noted that any zero-symmetric near-ring can be embedded in an equiprime near-ring. Moreover, the class of equiprime near-rings is shown to be hereditary. Open questions arising out of the study of equiprime near-rings are highlighted along the way. In Chapter 3 we consider well known examples of near-rings and determine when such near-rings are equiprime. This provides more insight into the nature of equiprime near-rings and is a fertile ground for the birth of examples and counterexamples which may be used to close or solve some open question within the literature. We also prove some results which generalize some results of Booth and Hall [10] and Veldsman [29]. These results have not been previously presented elsewhere to the best of our knowledge. vii In Chapter 4, the equiprime near-rings are shown to yield an ideal-hereditary radical in N∘. It is shown that a special radical theory can be built on the equiprime nearrings in much the same way prime rings are used in ring theory to define special radical classes of rings.
- Full Text:
- Date Issued: 2008
Lattice-valued continuous convergence is induced by a lattice-valued uniform convergence structure
- Authors: Jäger, Gunter
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6824 , http://hdl.handle.net/10962/d1012332
- Description: We define a stratified L-uniform convergence structure on the set of all continuous mappings from a stratified L-limit space to a stratified L-uniform convergence space. This structure induces L-continuous convergence. This shows that the category of all L-limit-uniformizable spaces is cartesian closed.
- Full Text:
- Date Issued: 2006
- Authors: Jäger, Gunter
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6824 , http://hdl.handle.net/10962/d1012332
- Description: We define a stratified L-uniform convergence structure on the set of all continuous mappings from a stratified L-limit space to a stratified L-uniform convergence space. This structure induces L-continuous convergence. This shows that the category of all L-limit-uniformizable spaces is cartesian closed.
- Full Text:
- Date Issued: 2006
Primeness in near-rings of continuous maps
- Authors: Mogae, Kabelo
- Subjects: Near-rings , Topological algebras
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10512 , http://hdl.handle.net/10948/d1020597
- Description: The prototype of a near-ring is the set of all self-maps of an additively written (but not necessarily abelian) group under pointwise addition and composition of maps. Moreover, any near-ring with unity can be embedded in a near-ring (with unity) of self-maps of some group. For this reason, a lot of research has been done on near-rings of maps. In 1979, Hofer [16] gave the study of near-rings of maps a topological avour by considering the near- ring of all continuous self-maps of a topological group. In this dissertation we consider some standard constructions of near-rings of maps on a group G and investigate these when G is a topological group and our near-ring consists of continuous maps.
- Full Text:
- Authors: Mogae, Kabelo
- Subjects: Near-rings , Topological algebras
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10512 , http://hdl.handle.net/10948/d1020597
- Description: The prototype of a near-ring is the set of all self-maps of an additively written (but not necessarily abelian) group under pointwise addition and composition of maps. Moreover, any near-ring with unity can be embedded in a near-ring (with unity) of self-maps of some group. For this reason, a lot of research has been done on near-rings of maps. In 1979, Hofer [16] gave the study of near-rings of maps a topological avour by considering the near- ring of all continuous self-maps of a topological group. In this dissertation we consider some standard constructions of near-rings of maps on a group G and investigate these when G is a topological group and our near-ring consists of continuous maps.
- Full Text:
Comparative phylogeography of five swallowtail butterfly species (Lepidoptera: Papilionidae) in South Africa : ecological and taxonomic implications.
- Authors: Neef, Götz-Georg
- Date: 2014
- Subjects: Swallowtail butterflies , Papilionidae -- South Africa , Phylogeography -- South Africa , Swallowtail butterflies -- Effect of habitat modification on , Biodiversity -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4266 , http://hdl.handle.net/10962/d1013574
- Description: With current biota under constant threat of extinction, it is important to ascertain where and how biological diversity is generated and partitioned. Phylogeographic studies can assist in the identification of places and processes that indicate the origin and maintenance of biodiversity. Forest fragmentation has a big effect on local extinction and loss of genetic diversity of forest-restricted taxa, along with divergence and speciation of forest biota. This study aims to understand the effects of these processes on a number of forest-dwelling butterflies using a comparative phylogeographic approach. Mitochondrial DNA of five different Papilio species with different degrees of forest specificity was analysed using phylogenetic methods. In addition, the subspecific taxonomy of P. ophidicephalus was investigated using morphometrics of discal spots on the wings and nuclear DNA analysis along with mitochondrial DNA analysis. The results show that the forest-restricted species (P. ophidicephalus and P. echerioides) have more genetic structure and less genetic diversity than the more generalist species (P. dardanus, P. demodocus and P. nireus). This could be due to inbreeding depression and bottlenecks caused by forest fragmentation. As forest patches become smaller, the population size is affected and that causes a loss in genetic diversity, and increasing habitat fragmentation disrupts gene flow. The intraspecific taxonomy of P. ophidicephalus is far from revealed. However, this study shows there is evidence for the different subspecies when comparing morphological results and genetic results. From the evidence provided here it is suggested that P. ophidicephalus should be divided into two separate species rather than five subspecies.
- Full Text:
- Date Issued: 2014
- Authors: Neef, Götz-Georg
- Date: 2014
- Subjects: Swallowtail butterflies , Papilionidae -- South Africa , Phylogeography -- South Africa , Swallowtail butterflies -- Effect of habitat modification on , Biodiversity -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4266 , http://hdl.handle.net/10962/d1013574
- Description: With current biota under constant threat of extinction, it is important to ascertain where and how biological diversity is generated and partitioned. Phylogeographic studies can assist in the identification of places and processes that indicate the origin and maintenance of biodiversity. Forest fragmentation has a big effect on local extinction and loss of genetic diversity of forest-restricted taxa, along with divergence and speciation of forest biota. This study aims to understand the effects of these processes on a number of forest-dwelling butterflies using a comparative phylogeographic approach. Mitochondrial DNA of five different Papilio species with different degrees of forest specificity was analysed using phylogenetic methods. In addition, the subspecific taxonomy of P. ophidicephalus was investigated using morphometrics of discal spots on the wings and nuclear DNA analysis along with mitochondrial DNA analysis. The results show that the forest-restricted species (P. ophidicephalus and P. echerioides) have more genetic structure and less genetic diversity than the more generalist species (P. dardanus, P. demodocus and P. nireus). This could be due to inbreeding depression and bottlenecks caused by forest fragmentation. As forest patches become smaller, the population size is affected and that causes a loss in genetic diversity, and increasing habitat fragmentation disrupts gene flow. The intraspecific taxonomy of P. ophidicephalus is far from revealed. However, this study shows there is evidence for the different subspecies when comparing morphological results and genetic results. From the evidence provided here it is suggested that P. ophidicephalus should be divided into two separate species rather than five subspecies.
- Full Text:
- Date Issued: 2014
Assessing the role of leadership in strategic planning
- Authors: Solomon, Wesley Anthony
- Date: 2006
- Subjects: Leadership , Strategic planning , Management
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8758 , http://hdl.handle.net/10948/609 , Leadership , Strategic planning , Management
- Description: Effective leadership is one of the most important factors that influence the performance of an organization. Effective leadership together with supervision are similar in terms of their influence on others towards achieving the goals of the organization. Therefore, effective leadership and supervision are principal activities through which organizational goals and objectives are achieved.
- Full Text:
- Date Issued: 2006
- Authors: Solomon, Wesley Anthony
- Date: 2006
- Subjects: Leadership , Strategic planning , Management
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8758 , http://hdl.handle.net/10948/609 , Leadership , Strategic planning , Management
- Description: Effective leadership is one of the most important factors that influence the performance of an organization. Effective leadership together with supervision are similar in terms of their influence on others towards achieving the goals of the organization. Therefore, effective leadership and supervision are principal activities through which organizational goals and objectives are achieved.
- Full Text:
- Date Issued: 2006
Nahatangena
- Group of Shangaan men, Composer unknown, Tracey, Hugh
- Authors: Group of Shangaan men , Composer unknown , Tracey, Hugh
- Date: 1958-03-31
- Subjects: Folk music--Africa , Field recordings , Africa, Sub-Saharan , Africa Mozambique Manica f-mz
- Language: Chopi
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/249801 , vital:51869 , International Library of African Music, Rhodes University, Makhanda, South Africa , Hugh Tracey Field Tapes, Rhodes University, Makhanda, South Africa , HTFT570-M22 , Research no. M2G10
- Description: A kwaya topical song about describing the work on the mine and farms.
- Full Text: false
- Date Issued: 1958-03-31
- Authors: Group of Shangaan men , Composer unknown , Tracey, Hugh
- Date: 1958-03-31
- Subjects: Folk music--Africa , Field recordings , Africa, Sub-Saharan , Africa Mozambique Manica f-mz
- Language: Chopi
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/249801 , vital:51869 , International Library of African Music, Rhodes University, Makhanda, South Africa , Hugh Tracey Field Tapes, Rhodes University, Makhanda, South Africa , HTFT570-M22 , Research no. M2G10
- Description: A kwaya topical song about describing the work on the mine and farms.
- Full Text: false
- Date Issued: 1958-03-31
Umtagato-we!
- The Coal Brothers, Composer unknown, Tracey, Hugh
- Authors: The Coal Brothers , Composer unknown , Tracey, Hugh
- Date: 1958-03-31
- Subjects: Folk music--Africa , Field recordings , Africa, Sub-Saharan , Africa Eswatini Havelock f-sq
- Language: Swati
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/249848 , vital:51875 , International Library of African Music, Rhodes University, Makhanda, South Africa , Hugh Tracey Field Tapes, Rhodes University, Makhanda, South Africa , HTFT570-M22 , Research no. M2G13
- Description: Town dance music.
- Full Text: false
- Date Issued: 1958-03-31
- Authors: The Coal Brothers , Composer unknown , Tracey, Hugh
- Date: 1958-03-31
- Subjects: Folk music--Africa , Field recordings , Africa, Sub-Saharan , Africa Eswatini Havelock f-sq
- Language: Swati
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/249848 , vital:51875 , International Library of African Music, Rhodes University, Makhanda, South Africa , Hugh Tracey Field Tapes, Rhodes University, Makhanda, South Africa , HTFT570-M22 , Research no. M2G13
- Description: Town dance music.
- Full Text: false
- Date Issued: 1958-03-31
Ichinenjane lapa mkoponi
- The Coal Brothers, Composer unknown, Tracey, Hugh
- Authors: The Coal Brothers , Composer unknown , Tracey, Hugh
- Date: 1958-03-31
- Subjects: Folk music--Africa , Field recordings , Africa, Sub-Saharan , Africa Eswatini Havelock f-sq
- Language: Swati
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/249831 , vital:51873 , International Library of African Music, Rhodes University, Makhanda, South Africa , Hugh Tracey Field Tapes, Rhodes University, Makhanda, South Africa , HTFT570-M22 , Research no. M2G12
- Description: Town dance music.
- Full Text: false
- Date Issued: 1958-03-31
- Authors: The Coal Brothers , Composer unknown , Tracey, Hugh
- Date: 1958-03-31
- Subjects: Folk music--Africa , Field recordings , Africa, Sub-Saharan , Africa Eswatini Havelock f-sq
- Language: Swati
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/249831 , vital:51873 , International Library of African Music, Rhodes University, Makhanda, South Africa , Hugh Tracey Field Tapes, Rhodes University, Makhanda, South Africa , HTFT570-M22 , Research no. M2G12
- Description: Town dance music.
- Full Text: false
- Date Issued: 1958-03-31
A model for a context aware machine-based personal memory manager and its implementation using a visual programming environment
- Authors: Tsegaye, Melekam Asrat
- Date: 2007
- Subjects: Visual programming (Computer science) Memory management (Computer science) Memory -- Data processing
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4640 , http://hdl.handle.net/10962/d1006563
- Description: Memory is a part of cognition. It is essential for an individual to function normally in society. It encompasses an individual's lifetime experience, thus defining his identity. This thesis develops the concept of a machine-based personal memory manager which captures and manages an individual's day-to-day external memories. Rather than accumulating large amounts of data which has to be mined for useful memories, the machine-based memory manager automatically organizes memories as they are captured to enable their quick retrieval and use. The main functions of the machine-based memory manager envisioned in this thesis are the support and the augmentation of an individual's biological memory system. In the thesis, a model for a machine-based memory manager is developed. A visual programming environment, which can be used to build context aware applications as well as a proof-of-concept machine-based memory manager, is conceptualized and implemented. An experimental machine-based memory manager is implemented and evaluated. The model describes a machine-based memory manager which manages an individual's external memories by context. It addresses the management of external memories which accumulate over long periods of time by proposing a context aware file system which automatically organizes external memories by context. It describes how personal memory management can be facilitated by machine using six entities (life streams, memory producers, memory consumers, a memory manager, memory fragments and context descriptors) and the processes in which these entities participate (memory capture, memory encoding and decoding, memory decoding and retrieval). The visual programming environment represents a development tool which contains facilities that support context aware application programming. For example, it provides facilities which enable the definition and use of virtual sensors. It enables rapid programming with a focus on component re-use and dynamic composition of applications through a visual interface. The experimental machine-based memory manager serves as an example implementation of the machine-based memory manager which is described by the model developed in this thesis. The hardware used in its implementation consists of widely available components such as a camera, microphone and sub-notebook computer which are assembled in the form of a wearable computer. The software is constructed using the visual programming environment developed in this thesis. It contains multiple sensor drivers, context interpreters, a context aware file system as well as memory retrieval and presentation interfaces. The evaluation of the machine-based memory manager shows that it is possible to create a machine which monitors the states of an individual and his environment, and manages his external memories, thus supporting and augmenting his biological memory.
- Full Text:
- Date Issued: 2007
- Authors: Tsegaye, Melekam Asrat
- Date: 2007
- Subjects: Visual programming (Computer science) Memory management (Computer science) Memory -- Data processing
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4640 , http://hdl.handle.net/10962/d1006563
- Description: Memory is a part of cognition. It is essential for an individual to function normally in society. It encompasses an individual's lifetime experience, thus defining his identity. This thesis develops the concept of a machine-based personal memory manager which captures and manages an individual's day-to-day external memories. Rather than accumulating large amounts of data which has to be mined for useful memories, the machine-based memory manager automatically organizes memories as they are captured to enable their quick retrieval and use. The main functions of the machine-based memory manager envisioned in this thesis are the support and the augmentation of an individual's biological memory system. In the thesis, a model for a machine-based memory manager is developed. A visual programming environment, which can be used to build context aware applications as well as a proof-of-concept machine-based memory manager, is conceptualized and implemented. An experimental machine-based memory manager is implemented and evaluated. The model describes a machine-based memory manager which manages an individual's external memories by context. It addresses the management of external memories which accumulate over long periods of time by proposing a context aware file system which automatically organizes external memories by context. It describes how personal memory management can be facilitated by machine using six entities (life streams, memory producers, memory consumers, a memory manager, memory fragments and context descriptors) and the processes in which these entities participate (memory capture, memory encoding and decoding, memory decoding and retrieval). The visual programming environment represents a development tool which contains facilities that support context aware application programming. For example, it provides facilities which enable the definition and use of virtual sensors. It enables rapid programming with a focus on component re-use and dynamic composition of applications through a visual interface. The experimental machine-based memory manager serves as an example implementation of the machine-based memory manager which is described by the model developed in this thesis. The hardware used in its implementation consists of widely available components such as a camera, microphone and sub-notebook computer which are assembled in the form of a wearable computer. The software is constructed using the visual programming environment developed in this thesis. It contains multiple sensor drivers, context interpreters, a context aware file system as well as memory retrieval and presentation interfaces. The evaluation of the machine-based memory manager shows that it is possible to create a machine which monitors the states of an individual and his environment, and manages his external memories, thus supporting and augmenting his biological memory.
- Full Text:
- Date Issued: 2007
Personality Theories and Social Psychology: PSY 211
- Authors: Hoho, V , Kheswa, J G
- Date: 2011-05
- Language: English
- Type: Examination paper
- Identifier: vital:18038 , http://hdl.handle.net/10353/d1010622
- Description: Personality Theories and Social Psychology: PSY 211, degree examination May/June 2011.
- Full Text: false
- Date Issued: 2011-05
- Authors: Hoho, V , Kheswa, J G
- Date: 2011-05
- Language: English
- Type: Examination paper
- Identifier: vital:18038 , http://hdl.handle.net/10353/d1010622
- Description: Personality Theories and Social Psychology: PSY 211, degree examination May/June 2011.
- Full Text: false
- Date Issued: 2011-05
Invariant control systems and sub-Riemannian structures on lie groups: equivalence and isometries
- Authors: Biggs, Rory
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64815 , vital:28607
- Description: In this thesis we consider invariant optimal control problems and invariant sub-Riemannian structures on Lie groups. Primarily, we are concerned with the equivalence and classification of problems (resp. structures). In the first chapter, both the class of invariant optimal control problems and the class of invariant sub-Riemannian structures are organised as categories. The latter category is shown to be functorially equivalent to a subcategory of the former category. Via the Pontryagin Maximum Principle, we associate to each invariant optimal control problem (resp. invariant sub-Riemannian structure) a quadratic Hamilton-Poisson system on the associated Lie-Poisson space. These Hamiltonian systems are also organised as a category and hence the Pontryagin lift is realised as a contravariant functor. Basic properties of these categories are investigated. The rest of this thesis is concerned with the classification (and investigation) of certain subclasses of structures and systems. In the second chapter, the homogeneous positive semidefinite quadratic Hamilton-Poisson systems on three-dimensional Lie-Poisson spaces are classified up to compatibility with a linear isomorphism; a list of 23 normal forms is exhibited. In the third chapter, we classify the invariant sub-Riemannian structures in three dimensions and calculate the isometry group for each normal form. By comparing our results with known results, we show that most isometries (in three dimensions) are in fact the composition of a left translation and a Lie group isomorphism. In the fourth and last chapter of this thesis, we classify the sub-Riemannian and Riemannian structures on the (2n + 1)-dimensional Heisenberg groups. Furthermore, we find the isometry group and geodesics of each normal form.
- Full Text:
- Date Issued: 2015
- Authors: Biggs, Rory
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64815 , vital:28607
- Description: In this thesis we consider invariant optimal control problems and invariant sub-Riemannian structures on Lie groups. Primarily, we are concerned with the equivalence and classification of problems (resp. structures). In the first chapter, both the class of invariant optimal control problems and the class of invariant sub-Riemannian structures are organised as categories. The latter category is shown to be functorially equivalent to a subcategory of the former category. Via the Pontryagin Maximum Principle, we associate to each invariant optimal control problem (resp. invariant sub-Riemannian structure) a quadratic Hamilton-Poisson system on the associated Lie-Poisson space. These Hamiltonian systems are also organised as a category and hence the Pontryagin lift is realised as a contravariant functor. Basic properties of these categories are investigated. The rest of this thesis is concerned with the classification (and investigation) of certain subclasses of structures and systems. In the second chapter, the homogeneous positive semidefinite quadratic Hamilton-Poisson systems on three-dimensional Lie-Poisson spaces are classified up to compatibility with a linear isomorphism; a list of 23 normal forms is exhibited. In the third chapter, we classify the invariant sub-Riemannian structures in three dimensions and calculate the isometry group for each normal form. By comparing our results with known results, we show that most isometries (in three dimensions) are in fact the composition of a left translation and a Lie group isomorphism. In the fourth and last chapter of this thesis, we classify the sub-Riemannian and Riemannian structures on the (2n + 1)-dimensional Heisenberg groups. Furthermore, we find the isometry group and geodesics of each normal form.
- Full Text:
- Date Issued: 2015
Control and integrability on SO (3)
- Authors: Remsing, C C
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6787 , http://hdl.handle.net/10962/d1006938
- Description: This paper considers control ane left- invariant systems evolving on matrix Lie groups. Such systems have signicant applications in a variety of elds. Any left-invariant optimal control problem (with quadratic cost) can be lifted, via the celebrated Maximum Principle, to a Hamiltonian system on the dual of the Lie algebra of the underlying state space G. The (minus) Lie-Poisson structure on the dual space g is used to describe the (normal) extremal curves. An interesting, and rather typical, single-input con- trol system on the rotation group SO (3) is investi- gated in some detail. The reduced Hamilton equa- tions associated with an extremal curve are derived in a simple and elegant manner. Finally, these equations are explicitly integrated by Jacobi elliptic functions.
- Full Text:
- Date Issued: 2010
- Authors: Remsing, C C
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6787 , http://hdl.handle.net/10962/d1006938
- Description: This paper considers control ane left- invariant systems evolving on matrix Lie groups. Such systems have signicant applications in a variety of elds. Any left-invariant optimal control problem (with quadratic cost) can be lifted, via the celebrated Maximum Principle, to a Hamiltonian system on the dual of the Lie algebra of the underlying state space G. The (minus) Lie-Poisson structure on the dual space g is used to describe the (normal) extremal curves. An interesting, and rather typical, single-input con- trol system on the rotation group SO (3) is investi- gated in some detail. The reduced Hamilton equa- tions associated with an extremal curve are derived in a simple and elegant manner. Finally, these equations are explicitly integrated by Jacobi elliptic functions.
- Full Text:
- Date Issued: 2010
Contributions to the theory of group rings
- Groenewald, Nicolas Johannes
- Authors: Groenewald, Nicolas Johannes
- Date: 1979
- Subjects: Group rings Group theory -- Mathematics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5391 , http://hdl.handle.net/10962/d1001980
- Description: Chapter 1 is a short review of the main results in some areas of the theory of group rings. In the first half of Chapter 2 we determine the ideal theoretic structure of the group ring RG where G is the direct product of a finite Abelian group and an ordered group with R a completely primary ring. Our choice of rings and groups entails that the study centres mainly on zero divisor ideals of group rings and hence it contributes in a small way to the zero divisor problem. We show that if R is a completely primary ring, then there exists a one-one correspondence of the prime zero divisor ideals in RG and RG¯, G finite cyclic of order n. If R is a ring with the property α, β € R, then αβ = 0 implies βα = 0, and S is an ordered semigroup, we show that if ∑α¡s¡ ∈ RS is a divisor of zero, then the coefficients α¡ belong to a zero divisor ideal in R. The converse is proved in the case where R is a commutative Noetherian ring. These results are applied to give an account of the zero divisors in the group ring over the direct product of a finite Abelian group and an ordered group with coefficients in a completely primary ring. In the second half of Chapter 2 we determine the units of the group ring RG where R is not necessarily commutative and G is an ordered group. If R is a ring such that if α, β € R and αβ = 0, then βα = 0, and if G is an ordered group, then we show that ∑αg(subscript)g is a unit in RG if and only if there exists ∑βh(subscript)h in RG such that∑αg(subscript)βg(subscript)-1 = 1 and αg(subscriptβh is nilpotent whenever GH≠1. We also show that if R is a ring with no nilpotent elements ≠0 and no idempotents ≠0,1, then RG has only trivial units. In this chapter we also consider strongly prime rings. We prove that RG is strongly prime if R is strongly prime and G is an unique product (u.p.) group. If H ⊲ G such that G/H is right ordered, then it is shown that RG is strongly prime if RH is strongly prime. In Chapter 3 results are derived to indicate the relations between certain classes of ideals in R and RG. If δ is a property of ideals defined for ideals in R and RG, then the "going up" condition holds for δ-ideals if Q being a δ-ideal in R implies that QG is a δ-ideal in RG. The "going down" condition is satisfied if P being a δ-ideal in RG implies that P∩ R is a δ-ideal in R. We proved that the "going up" and "going down" conditions are satisfied for prime ideals, ℓ-prime ideals, q-semiprime ideals and strongly prime ideals. These results are then applied to obtain certain relations between different radicals of the ring R and the group ring (semigroup ring) RG (RS). Similarly, results about the relation between the ideals and the radicals of the group rings RH and RG, where H is a central subgroup of G, are obtained. For the upper nil radical we prove that ⋃(RG) (RH) ⊆ RG, H a central subgroup of G, if G/H is an ordered group . If S is an ordered semigroup, however, then ⋃(RS) ⊆ ⋃(R)S for any ring R. In Chapter 4 we determine relations between various radicals in certain classes of group rings. In Section 4.3, as an extension of a result of Tan, we prove that P(R)G = P(RG) , R a ring with identity , if and only if the order of no finite normal subgroup of G is a zero divisor in R/P(R). If R is any ring with identity and H a normal subgroup of G such that G/H is an ordered group, we show that ⊓(RH)·RG = ⋃(RG) = ⊓(RG) , if ⋃(RH) is nilpotent. Similar results are obtained for the semigroup ring RS, S ordered. It is also shown if R is commutative and G finite of order n, then J(R)G = J(RG) if and only if n is not a zero divisor in R/J(R), J(R) being the Jacobson radical of R. For the Brown HcCoy radical we determine the following: If R is Brown McCoy semisimple or if R is a simple ring with identity, then B(RG) = (0), where G is a finitely generated torsion free Abelian group. In the last section we determine further relations between some of the previously defined radicals, in particular between P(R), U(R) and J(R). Among other results, the following relations between the abovementioned radicals are obtained: U(RS) = U(R)S = P(RS) = J(RS) where R is a left Goldie ring and S an ordered semigroup with unity
- Full Text:
- Date Issued: 1979
- Authors: Groenewald, Nicolas Johannes
- Date: 1979
- Subjects: Group rings Group theory -- Mathematics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5391 , http://hdl.handle.net/10962/d1001980
- Description: Chapter 1 is a short review of the main results in some areas of the theory of group rings. In the first half of Chapter 2 we determine the ideal theoretic structure of the group ring RG where G is the direct product of a finite Abelian group and an ordered group with R a completely primary ring. Our choice of rings and groups entails that the study centres mainly on zero divisor ideals of group rings and hence it contributes in a small way to the zero divisor problem. We show that if R is a completely primary ring, then there exists a one-one correspondence of the prime zero divisor ideals in RG and RG¯, G finite cyclic of order n. If R is a ring with the property α, β € R, then αβ = 0 implies βα = 0, and S is an ordered semigroup, we show that if ∑α¡s¡ ∈ RS is a divisor of zero, then the coefficients α¡ belong to a zero divisor ideal in R. The converse is proved in the case where R is a commutative Noetherian ring. These results are applied to give an account of the zero divisors in the group ring over the direct product of a finite Abelian group and an ordered group with coefficients in a completely primary ring. In the second half of Chapter 2 we determine the units of the group ring RG where R is not necessarily commutative and G is an ordered group. If R is a ring such that if α, β € R and αβ = 0, then βα = 0, and if G is an ordered group, then we show that ∑αg(subscript)g is a unit in RG if and only if there exists ∑βh(subscript)h in RG such that∑αg(subscript)βg(subscript)-1 = 1 and αg(subscriptβh is nilpotent whenever GH≠1. We also show that if R is a ring with no nilpotent elements ≠0 and no idempotents ≠0,1, then RG has only trivial units. In this chapter we also consider strongly prime rings. We prove that RG is strongly prime if R is strongly prime and G is an unique product (u.p.) group. If H ⊲ G such that G/H is right ordered, then it is shown that RG is strongly prime if RH is strongly prime. In Chapter 3 results are derived to indicate the relations between certain classes of ideals in R and RG. If δ is a property of ideals defined for ideals in R and RG, then the "going up" condition holds for δ-ideals if Q being a δ-ideal in R implies that QG is a δ-ideal in RG. The "going down" condition is satisfied if P being a δ-ideal in RG implies that P∩ R is a δ-ideal in R. We proved that the "going up" and "going down" conditions are satisfied for prime ideals, ℓ-prime ideals, q-semiprime ideals and strongly prime ideals. These results are then applied to obtain certain relations between different radicals of the ring R and the group ring (semigroup ring) RG (RS). Similarly, results about the relation between the ideals and the radicals of the group rings RH and RG, where H is a central subgroup of G, are obtained. For the upper nil radical we prove that ⋃(RG) (RH) ⊆ RG, H a central subgroup of G, if G/H is an ordered group . If S is an ordered semigroup, however, then ⋃(RS) ⊆ ⋃(R)S for any ring R. In Chapter 4 we determine relations between various radicals in certain classes of group rings. In Section 4.3, as an extension of a result of Tan, we prove that P(R)G = P(RG) , R a ring with identity , if and only if the order of no finite normal subgroup of G is a zero divisor in R/P(R). If R is any ring with identity and H a normal subgroup of G such that G/H is an ordered group, we show that ⊓(RH)·RG = ⋃(RG) = ⊓(RG) , if ⋃(RH) is nilpotent. Similar results are obtained for the semigroup ring RS, S ordered. It is also shown if R is commutative and G finite of order n, then J(R)G = J(RG) if and only if n is not a zero divisor in R/J(R), J(R) being the Jacobson radical of R. For the Brown HcCoy radical we determine the following: If R is Brown McCoy semisimple or if R is a simple ring with identity, then B(RG) = (0), where G is a finitely generated torsion free Abelian group. In the last section we determine further relations between some of the previously defined radicals, in particular between P(R), U(R) and J(R). Among other results, the following relations between the abovementioned radicals are obtained: U(RS) = U(R)S = P(RS) = J(RS) where R is a left Goldie ring and S an ordered semigroup with unity
- Full Text:
- Date Issued: 1979
A mathematical investigation of the effects of sexual orientation and HIV status on HPV transmission and vaccination
- Authors: Holtzhausen, Tresia Louisa
- Date: 2013
- Subjects: Virus diseases -- Mathematical models , Cervix uteri -- Cancer -- Treatment , Sexual orientation , Immune response -- Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3946 , vital:20494
- Description: The effect of the inclusion of sexual behaviour, particularly three sexual orientation classes, on the transmission dynamics of HPV and cervical cancer incidence was investigated. A comprehensive literature review of mathematical models of HPV transmission and the natural history of cervical cancer was concluded. A mathematical model using ordinary differential equations was developed, which incorporated the three sexual orientation classes, and a sexual mixing algorithm for modelling the transmission dynamics. Reproduction numbers, determined through a simplified version of the developed model, indicated that the bisexual population could form a bridge between the heterosexual and homosexual population. The level of interaction is determined by the selection preferences of a bisexual individual to form a partnership with an individual of the same or opposite sex. The model was simulated, with parameters based on a South African population and HPV type 16/18, to investigate the effects of HIV status, sexual orientation and various vaccination strategies on HPV transmission and cervical cancer incidence. The results indicated that HIV status is a significant factor when determining cervical cancer incidence. The results regarding vaccination strategies agreed with results from the literature review with a two sex before sexual debut and catch up program the most effective, noting that with increased vaccination coverage of females the marginal impact on cervical cancer incidence of this approach diminished.
- Full Text:
- Date Issued: 2013
- Authors: Holtzhausen, Tresia Louisa
- Date: 2013
- Subjects: Virus diseases -- Mathematical models , Cervix uteri -- Cancer -- Treatment , Sexual orientation , Immune response -- Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3946 , vital:20494
- Description: The effect of the inclusion of sexual behaviour, particularly three sexual orientation classes, on the transmission dynamics of HPV and cervical cancer incidence was investigated. A comprehensive literature review of mathematical models of HPV transmission and the natural history of cervical cancer was concluded. A mathematical model using ordinary differential equations was developed, which incorporated the three sexual orientation classes, and a sexual mixing algorithm for modelling the transmission dynamics. Reproduction numbers, determined through a simplified version of the developed model, indicated that the bisexual population could form a bridge between the heterosexual and homosexual population. The level of interaction is determined by the selection preferences of a bisexual individual to form a partnership with an individual of the same or opposite sex. The model was simulated, with parameters based on a South African population and HPV type 16/18, to investigate the effects of HIV status, sexual orientation and various vaccination strategies on HPV transmission and cervical cancer incidence. The results indicated that HIV status is a significant factor when determining cervical cancer incidence. The results regarding vaccination strategies agreed with results from the literature review with a two sex before sexual debut and catch up program the most effective, noting that with increased vaccination coverage of females the marginal impact on cervical cancer incidence of this approach diminished.
- Full Text:
- Date Issued: 2013
Opname van die Kaapse Middelland en Karroogebied: deel 1: n Geografiese studie van die Kaapse middelland- en Karroogebied, met spesiale verwysing na die fisiografie en elemente van bodembenutting
- Authors: Badenhorst, J J
- Date: 1970
- Subjects: Geology -- South Africa Geomorphology -- South Africa Agriculture -- South Africa Orange/fish river project Sheep -- South Africa Goats -- South Africa Chicory -- South Africa Pineapple industry -- South Africa Feeds -- South Africa Forests and forestry -- South Africa Fruit -- South Africa South Africa -- Climate South Africa -- Geography
- Language: Afrikaans
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2612 , vital:20309
- Description: In 1966 het die Karoo-ontwikkelingvereniging die Universiteit Rhodes genader met 'n versoek dat die Universiteit Rhodes se Instituut vir Sosiale en Ekonomiese Navorsing 'n sosio-ekonomiese Opname van hulle streek sou maak om 'n feitegrondslag vir ontwikkelingsbeplanning te verskaf in afwagting van die voltooiing van die Oranjerivier-projek. Soortgelyke versoeke is van die Middellande-Ontwikkelingsvereniging en die Vereniging van Openbare Liggame van die Suid-Oostelike Distrikte ontvang. Nadat die Departement van Beplanning, wat die idee van 'n streeksopname sterk ondersteun het, geraadpleeg is, is daar ooreengekom dat hoewel Port Elizabeth en sy agterland 'n gemeenskaplike ekonomiese eenheid vorm, die gebied onderverdeel kon word, en dat die Universiteit van Port Elizabeth verantwoordelikheid vir die stedelike gebied Port Elizabeth en Uitenhage sou aanvaar, en die Universiteit Rhodes, deur die Instituut vir Sosiale en Ekonomiese Navorsing die Opname van die binnelandse gebiede sou lei. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1970
- Authors: Badenhorst, J J
- Date: 1970
- Subjects: Geology -- South Africa Geomorphology -- South Africa Agriculture -- South Africa Orange/fish river project Sheep -- South Africa Goats -- South Africa Chicory -- South Africa Pineapple industry -- South Africa Feeds -- South Africa Forests and forestry -- South Africa Fruit -- South Africa South Africa -- Climate South Africa -- Geography
- Language: Afrikaans
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2612 , vital:20309
- Description: In 1966 het die Karoo-ontwikkelingvereniging die Universiteit Rhodes genader met 'n versoek dat die Universiteit Rhodes se Instituut vir Sosiale en Ekonomiese Navorsing 'n sosio-ekonomiese Opname van hulle streek sou maak om 'n feitegrondslag vir ontwikkelingsbeplanning te verskaf in afwagting van die voltooiing van die Oranjerivier-projek. Soortgelyke versoeke is van die Middellande-Ontwikkelingsvereniging en die Vereniging van Openbare Liggame van die Suid-Oostelike Distrikte ontvang. Nadat die Departement van Beplanning, wat die idee van 'n streeksopname sterk ondersteun het, geraadpleeg is, is daar ooreengekom dat hoewel Port Elizabeth en sy agterland 'n gemeenskaplike ekonomiese eenheid vorm, die gebied onderverdeel kon word, en dat die Universiteit van Port Elizabeth verantwoordelikheid vir die stedelike gebied Port Elizabeth en Uitenhage sou aanvaar, en die Universiteit Rhodes, deur die Instituut vir Sosiale en Ekonomiese Navorsing die Opname van die binnelandse gebiede sou lei. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1970
Settlement wage agreement 2014/2015 between Breakfast Cereals Atlantis Operating Unit and ProNutro Wadeville Operating Unit as part of Pioneer Foods Groceries Business and Food and Allied Workers Union
- Pioneer Foods Groceries Business, Food and Allied Workers Union
- Authors: Pioneer Foods Groceries Business , Food and Allied Workers Union
- Date: 2014-07-30
- Subjects: Pioneer Foods Groceries Business , Wages -- South Africa , ProNutro Wadeville Operating Unit , Breakfast Cereals Atlantis Operating Unit , Food and Allied Workers Union (FAWU) , Collective bargaining -- South Africa
- Language: English
- Type: collective labor agreements , text
- Identifier: http://hdl.handle.net/10962/94376 , vital:31040 , Labour Research Service (LRS)
- Description: Settlement wage agreement 2014/2015 between Breakfast Cereals Atlantis Operating Unit and ProNutro Wadeville Operating Unit as part of Pioneer Foods Groceries Business and Food and Allied Workers Union.
- Full Text:
- Date Issued: 2014-07-30
- Authors: Pioneer Foods Groceries Business , Food and Allied Workers Union
- Date: 2014-07-30
- Subjects: Pioneer Foods Groceries Business , Wages -- South Africa , ProNutro Wadeville Operating Unit , Breakfast Cereals Atlantis Operating Unit , Food and Allied Workers Union (FAWU) , Collective bargaining -- South Africa
- Language: English
- Type: collective labor agreements , text
- Identifier: http://hdl.handle.net/10962/94376 , vital:31040 , Labour Research Service (LRS)
- Description: Settlement wage agreement 2014/2015 between Breakfast Cereals Atlantis Operating Unit and ProNutro Wadeville Operating Unit as part of Pioneer Foods Groceries Business and Food and Allied Workers Union.
- Full Text:
- Date Issued: 2014-07-30