"Is more, less?" : insect-insect interactions in a biological control context using water hyacinth as a model
- Weyl, Philip Sebastian Richard
- Authors: Weyl, Philip Sebastian Richard
- Date: 2012
- Subjects: Water hyacinth -- South Africa -- Eastern Cape , Water hyacinth -- Biological control -- South Africa -- Eastern Cape , Insects as biological pest control agents , Miridae -- South Africa -- Eastern Cape , Beetles -- South Africa -- Eastern Cape , Competition (Biology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5724 , http://hdl.handle.net/10962/d1005410 , Water hyacinth -- South Africa -- Eastern Cape , Water hyacinth -- Biological control -- South Africa -- Eastern Cape , Insects as biological pest control agents , Miridae -- South Africa -- Eastern Cape , Beetles -- South Africa -- Eastern Cape , Competition (Biology)
- Description: Interactions between insects have been shown to be important regulators of population abundances and dynamics as well as drivers of spatial segregation and distribution. These are important aspects of the ecology of insects used in biological control and may have implications for the overall success of a particular programme. In the history of biological control there has been a tendency to release a suite of agents against a weed, which in some cases has increased the level of success, while in others little change has been observed. In most of these cases the implications of increasing the level of complexity of the system is not taken into account and there is little research on the effect of releasing another agent into the system. A brief meta-analysis was done on all the biological control programmes initiated in South Africa. Emphasis was placed on multi-species releases and the effects that overlapping niches were having on the number of agents responsible for the success of a programme. Where overlapping niches were present among agents released the number of agents responsible for success was lower than the number established. Water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach in South Africa has more arthropod agents released against it than anywhere else in the world, yet control has been variable. If the biology and host utilisation of all the agents against water hyacinth is considered, a definite overlap of niches is apparent in at least one life stage of all the agents. Therefore the probability of these insects interacting is high, especially if they are established at the same site in the field. Three of the insects released in South Africa have been selected to investigate possible interactions. They are Neochetina eichhorniae Warner, Neochetina bruchi Hustache and Eccritotarsus catarinensis (Carvalho). Y-tube olfactometer bioassays were used to measure responses of these insects to water hyacinth with prior feeding damage by either conspecifics or heterospecifics. This was done to determine whether olfactory cues played a role in host acceptability and avoidance of conspecifics or heterospecifics. The insects were given a choice between damaged and undamaged plants in various combinations. There was a significant preference for the undamaged plants when given a choice between undamaged and damaged plants. However when the insects were given a choice between two damaged plants there was no discrimination between heterospecific or conspecific damaged plants. This may indicate that there is little or no ecological cost for the insect to share a plant with other insects utilising a similar resource. Insect – insect interactions were investigated in a common garden plot experiment to measure the impact that pairwise combinations of the insect may have on their performance. There was a significant interaction between the mirid E. catarinensis and the weevil N. eichhorniae, with the weevil not performing as well when in combination with the mirid than when alone. Interestingly there was a negative interaction between the two weevil species when in combination, however it was impossible to determine which species was being affected if not both. None of the insects performed significantly better when in combination with another insect. A field study on Wriggleswade Dam in the Eastern Cape, South Africa was initiated to determine whether the relationship between the mirid E. catarinensis and the weevil N. eichhorniae could be determined in the field. The performance of the insects at the different sites in the field suggests that there was an interaction between the agents. This interaction did not limit the establishment of either insect at a site, but it did result in one insect dominating at a site over another. Interactions between the three species of insect tested in this thesis suggest that there are both negative and neutral relationships between them. A basic comparison between the insect performances from 15 sites around the country was done to determine if the spatial segregation observed in the field could be extrapolated to the natural South African situation. The interaction observed between N. eichhorniae and E. catarinensis does seem to extrapolate to the general South African situation where there is definite spatial segregation on a landscape level. The co–occurrence of the two Neochetina weevils at these sites suggests that the negative relationship observed between them in the common garden experiment does not extrapolate to the field. The results from this thesis suggest that the interactions between the agents tested would not limit establishment or have significant ramifications on performance. However, there may be spatial and temporal segregation of these species in the introduced range.
- Full Text:
- Authors: Weyl, Philip Sebastian Richard
- Date: 2012
- Subjects: Water hyacinth -- South Africa -- Eastern Cape , Water hyacinth -- Biological control -- South Africa -- Eastern Cape , Insects as biological pest control agents , Miridae -- South Africa -- Eastern Cape , Beetles -- South Africa -- Eastern Cape , Competition (Biology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5724 , http://hdl.handle.net/10962/d1005410 , Water hyacinth -- South Africa -- Eastern Cape , Water hyacinth -- Biological control -- South Africa -- Eastern Cape , Insects as biological pest control agents , Miridae -- South Africa -- Eastern Cape , Beetles -- South Africa -- Eastern Cape , Competition (Biology)
- Description: Interactions between insects have been shown to be important regulators of population abundances and dynamics as well as drivers of spatial segregation and distribution. These are important aspects of the ecology of insects used in biological control and may have implications for the overall success of a particular programme. In the history of biological control there has been a tendency to release a suite of agents against a weed, which in some cases has increased the level of success, while in others little change has been observed. In most of these cases the implications of increasing the level of complexity of the system is not taken into account and there is little research on the effect of releasing another agent into the system. A brief meta-analysis was done on all the biological control programmes initiated in South Africa. Emphasis was placed on multi-species releases and the effects that overlapping niches were having on the number of agents responsible for the success of a programme. Where overlapping niches were present among agents released the number of agents responsible for success was lower than the number established. Water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach in South Africa has more arthropod agents released against it than anywhere else in the world, yet control has been variable. If the biology and host utilisation of all the agents against water hyacinth is considered, a definite overlap of niches is apparent in at least one life stage of all the agents. Therefore the probability of these insects interacting is high, especially if they are established at the same site in the field. Three of the insects released in South Africa have been selected to investigate possible interactions. They are Neochetina eichhorniae Warner, Neochetina bruchi Hustache and Eccritotarsus catarinensis (Carvalho). Y-tube olfactometer bioassays were used to measure responses of these insects to water hyacinth with prior feeding damage by either conspecifics or heterospecifics. This was done to determine whether olfactory cues played a role in host acceptability and avoidance of conspecifics or heterospecifics. The insects were given a choice between damaged and undamaged plants in various combinations. There was a significant preference for the undamaged plants when given a choice between undamaged and damaged plants. However when the insects were given a choice between two damaged plants there was no discrimination between heterospecific or conspecific damaged plants. This may indicate that there is little or no ecological cost for the insect to share a plant with other insects utilising a similar resource. Insect – insect interactions were investigated in a common garden plot experiment to measure the impact that pairwise combinations of the insect may have on their performance. There was a significant interaction between the mirid E. catarinensis and the weevil N. eichhorniae, with the weevil not performing as well when in combination with the mirid than when alone. Interestingly there was a negative interaction between the two weevil species when in combination, however it was impossible to determine which species was being affected if not both. None of the insects performed significantly better when in combination with another insect. A field study on Wriggleswade Dam in the Eastern Cape, South Africa was initiated to determine whether the relationship between the mirid E. catarinensis and the weevil N. eichhorniae could be determined in the field. The performance of the insects at the different sites in the field suggests that there was an interaction between the agents. This interaction did not limit the establishment of either insect at a site, but it did result in one insect dominating at a site over another. Interactions between the three species of insect tested in this thesis suggest that there are both negative and neutral relationships between them. A basic comparison between the insect performances from 15 sites around the country was done to determine if the spatial segregation observed in the field could be extrapolated to the natural South African situation. The interaction observed between N. eichhorniae and E. catarinensis does seem to extrapolate to the general South African situation where there is definite spatial segregation on a landscape level. The co–occurrence of the two Neochetina weevils at these sites suggests that the negative relationship observed between them in the common garden experiment does not extrapolate to the field. The results from this thesis suggest that the interactions between the agents tested would not limit establishment or have significant ramifications on performance. However, there may be spatial and temporal segregation of these species in the introduced range.
- Full Text:
'Becoming citizens': young people making sense of citizenship on a South African community radio station youth show
- Karamagi, Sharon Benna Kyakyo
- Authors: Karamagi, Sharon Benna Kyakyo
- Date: 2012
- Subjects: Citizenship -- Study and teaching -- South Africa Youth -- Social conditions Community radio -- South Africa -- Grahamstown Grahamstown (South Africa) -- Economic conditions
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3444 , http://hdl.handle.net/10962/d1002898
- Description: This research set out to investigate the role that community radio can potentially play as a space in which young people engage with their own role as citizens and, in so doing, participate in discussions that seek to address social problems in a community divided by class, income, gender and race. The study examines how a local community radio station - Radio Grahamstown - developed a youth programme Y4Yin which the producers of the show and its audience came together to negotiate the meaning of citizenship. The study examines whether this interactive programme was able to function as something like a public sphere where in young people were able to develop a greater sense of agency, at least in the realm of citizenship. Using evidence gathered through focus group discussions with a group of young school-going leamers, interviews conducted with the producers of the show Y4Y, and drawing on Dahlgren's elaboration of a functional public sphere, the research concludes that the show provided a useful platform for Grahamstown high school students to develop their own notions of citizenship and to, at least partially and tentatively, build some 'bridges' across the vectors of socio-economic division in the town. However, the research also concludes that the Y4Y producers often failed to use a mode of address contemporary to the youth and often did not use production techniques congruent with young people's cultural tastes. This limited the programme's appeal and its potential as an enabler of discussion about notions of citizenship and as a platform for social bridging. In addition, because of the producers' control over the choice of topics put up for discussion, open interaction was more limited than could have been expected. In addition, the study also concludes that various limitations to the leamers' freedom of expression (including their fear that teachers might be listening in to the shows) inhibited the programme's role as a deliberative public sphere where issues could be aired, common ground found, and solutions discussed.
- Full Text:
- Authors: Karamagi, Sharon Benna Kyakyo
- Date: 2012
- Subjects: Citizenship -- Study and teaching -- South Africa Youth -- Social conditions Community radio -- South Africa -- Grahamstown Grahamstown (South Africa) -- Economic conditions
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3444 , http://hdl.handle.net/10962/d1002898
- Description: This research set out to investigate the role that community radio can potentially play as a space in which young people engage with their own role as citizens and, in so doing, participate in discussions that seek to address social problems in a community divided by class, income, gender and race. The study examines how a local community radio station - Radio Grahamstown - developed a youth programme Y4Yin which the producers of the show and its audience came together to negotiate the meaning of citizenship. The study examines whether this interactive programme was able to function as something like a public sphere where in young people were able to develop a greater sense of agency, at least in the realm of citizenship. Using evidence gathered through focus group discussions with a group of young school-going leamers, interviews conducted with the producers of the show Y4Y, and drawing on Dahlgren's elaboration of a functional public sphere, the research concludes that the show provided a useful platform for Grahamstown high school students to develop their own notions of citizenship and to, at least partially and tentatively, build some 'bridges' across the vectors of socio-economic division in the town. However, the research also concludes that the Y4Y producers often failed to use a mode of address contemporary to the youth and often did not use production techniques congruent with young people's cultural tastes. This limited the programme's appeal and its potential as an enabler of discussion about notions of citizenship and as a platform for social bridging. In addition, because of the producers' control over the choice of topics put up for discussion, open interaction was more limited than could have been expected. In addition, the study also concludes that various limitations to the leamers' freedom of expression (including their fear that teachers might be listening in to the shows) inhibited the programme's role as a deliberative public sphere where issues could be aired, common ground found, and solutions discussed.
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(Dis)allowances of lesbians’ sexual identities: Lesbian identity construction in racialised, classed, familial, and institutional spaces
- Gibson, Alexandra F, Macleod, Catriona I
- Authors: Gibson, Alexandra F , Macleod, Catriona I
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6222 , http://hdl.handle.net/10962/d1006536 , http://dx.doi.org/10.1177/0959353512459580
- Description: This article explores how lesbian identity construction is facilitated and constrained by the raced, classed, gendered, familial, and geographical spaces that women occupy. We present a narrative-discursive analysis of eight lesbians’ stories of sexuality, told within a historically white university in South Africa. Three interpretative repertoires that emerged in the narratives are discussed. The ‘disallowance of lesbian identity in particular racialised and class-based spaces’ repertoire, deployed by black lesbians only, was used to account for their de-emphasis of a lesbian identity through the invocation of a threat of danger and stereotyping. The ‘disjuncture of the (heterosexual) family and lesbian identity’ repertoire emphasised how the expectation of support and care within a family does not necessarily extend to acceptance of a lesbian identity.
- Full Text:
- Authors: Gibson, Alexandra F , Macleod, Catriona I
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6222 , http://hdl.handle.net/10962/d1006536 , http://dx.doi.org/10.1177/0959353512459580
- Description: This article explores how lesbian identity construction is facilitated and constrained by the raced, classed, gendered, familial, and geographical spaces that women occupy. We present a narrative-discursive analysis of eight lesbians’ stories of sexuality, told within a historically white university in South Africa. Three interpretative repertoires that emerged in the narratives are discussed. The ‘disallowance of lesbian identity in particular racialised and class-based spaces’ repertoire, deployed by black lesbians only, was used to account for their de-emphasis of a lesbian identity through the invocation of a threat of danger and stereotyping. The ‘disjuncture of the (heterosexual) family and lesbian identity’ repertoire emphasised how the expectation of support and care within a family does not necessarily extend to acceptance of a lesbian identity.
- Full Text:
A baculovirus-mediated expression system for the analysis of HaSV RNA packaging
- Authors: Mendes, Adriano
- Date: 2012
- Subjects: RNA , Baculoviruses , Helicoverpa armigera , Plasmids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4025 , http://hdl.handle.net/10962/d1004085 , RNA , Baculoviruses , Helicoverpa armigera , Plasmids
- Description: The Helicoverpa armigera stunt virus (HaSV) is a member of a family of small nonenveloped (+) ssRNA insect viruses currently known as the Tetraviridae. This family is unique in terms of the T=4 quasi-symmetry of its capsid particles and the unusually narrow host range and tissue tropism. Assembly of tetraviral particles has been well characterised and involves the combination of 240 copies of a single capsid precursor protein (VCap) into a procapsid followed by autoproteolytic cleavage to yield the major (β) and minor (γ) capsid subunits within the mature particle. HaSV has two genomic RNAs, RNA 1 encoding the replicase and RNA 2 encoding VCap and p17, the ORF of which lies upstream of and overlaping with the 5’ end of the VCap ORF. Prior to this study, Vlok (2009) used a plasmid expression system to study RNA packaging in HaSV VLPs assembled in Spodoptera frugiperda 9 (Sf9) cells co-expressing p17 and VCap. The study showed that the p17 ORF was required for the packaging of RNA 2 during capsid assembly but it was unclear whether p17 expression was required for packaging. In addition, expression from the transfected plasmids was sub-optimal affecting both the yield of VLPs and the detection of p17. The aim of this study was to use the plasmid system to test whether p17 expression was required for plasmid-derived VLP RNA packaging and then develop a baculovirus-mediated system to test this hypothesis. By using a plasmid in which the start codon of p17 was mutated, it was shown that p17 expression was required for RNA 2 packaging into plasmid-VLPs. For the baculovirus system, four recombinant baculoviruses based upon the pFastBac Dual expression system, were constructed. These included Bac20, expressing wild type RNA 2, Bac21, RNA 2 with p17 silenced, Bac23, RNA 2 and p17 expressed on a separate transcript and Bac24, RNA 2 with p17 silenced plus p17 expressed on a separate transcript. Assembly of VLPs was more efficient using the baculovirus expression system and p17 expression was observed in cells infected with Bac20, Bac23 and Bac24, but not Bac21. In contrast to the plasmid-VLPs, bac-VLPs did not require p17 for the encapsidation of RNA 2. In addition to RNA 2, Bac23 and Bac24 packaged the p17 mRNA transcribed separately from RNA 2. This insinuated that bac-VLPs may be packaging RNA non-selectively. It was proposed that p17 may play a role in packaging in an RNA-limiting environment (plasmid system) but functioned differently when viral RNA was in excess (baculovirus system). This data points to the importance of developing a replication system for the analysis of the packaging pathways of these viruses and this study has laid down the foundations for such a system in which RNA 1 and RNA 2 can be introduced into a single cell by means of a single recombinant virus.
- Full Text:
- Authors: Mendes, Adriano
- Date: 2012
- Subjects: RNA , Baculoviruses , Helicoverpa armigera , Plasmids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4025 , http://hdl.handle.net/10962/d1004085 , RNA , Baculoviruses , Helicoverpa armigera , Plasmids
- Description: The Helicoverpa armigera stunt virus (HaSV) is a member of a family of small nonenveloped (+) ssRNA insect viruses currently known as the Tetraviridae. This family is unique in terms of the T=4 quasi-symmetry of its capsid particles and the unusually narrow host range and tissue tropism. Assembly of tetraviral particles has been well characterised and involves the combination of 240 copies of a single capsid precursor protein (VCap) into a procapsid followed by autoproteolytic cleavage to yield the major (β) and minor (γ) capsid subunits within the mature particle. HaSV has two genomic RNAs, RNA 1 encoding the replicase and RNA 2 encoding VCap and p17, the ORF of which lies upstream of and overlaping with the 5’ end of the VCap ORF. Prior to this study, Vlok (2009) used a plasmid expression system to study RNA packaging in HaSV VLPs assembled in Spodoptera frugiperda 9 (Sf9) cells co-expressing p17 and VCap. The study showed that the p17 ORF was required for the packaging of RNA 2 during capsid assembly but it was unclear whether p17 expression was required for packaging. In addition, expression from the transfected plasmids was sub-optimal affecting both the yield of VLPs and the detection of p17. The aim of this study was to use the plasmid system to test whether p17 expression was required for plasmid-derived VLP RNA packaging and then develop a baculovirus-mediated system to test this hypothesis. By using a plasmid in which the start codon of p17 was mutated, it was shown that p17 expression was required for RNA 2 packaging into plasmid-VLPs. For the baculovirus system, four recombinant baculoviruses based upon the pFastBac Dual expression system, were constructed. These included Bac20, expressing wild type RNA 2, Bac21, RNA 2 with p17 silenced, Bac23, RNA 2 and p17 expressed on a separate transcript and Bac24, RNA 2 with p17 silenced plus p17 expressed on a separate transcript. Assembly of VLPs was more efficient using the baculovirus expression system and p17 expression was observed in cells infected with Bac20, Bac23 and Bac24, but not Bac21. In contrast to the plasmid-VLPs, bac-VLPs did not require p17 for the encapsidation of RNA 2. In addition to RNA 2, Bac23 and Bac24 packaged the p17 mRNA transcribed separately from RNA 2. This insinuated that bac-VLPs may be packaging RNA non-selectively. It was proposed that p17 may play a role in packaging in an RNA-limiting environment (plasmid system) but functioned differently when viral RNA was in excess (baculovirus system). This data points to the importance of developing a replication system for the analysis of the packaging pathways of these viruses and this study has laid down the foundations for such a system in which RNA 1 and RNA 2 can be introduced into a single cell by means of a single recombinant virus.
- Full Text:
A case study describing factors perceived to be impacting staff satisfaction amongst health care professionals at the East London Hospital complex
- Authors: Galo, Luntu
- Date: 2012
- Subjects: Medical personnel -- Job satisfaction -- South Africa -- Case studies Medical personnel -- Job stress -- South Africa -- Case studies Medical personnel -- South Africa -- Attitudes -- Case studies Hospitals -- South Africa -- Administration Health services administration -- South Africa Health planning -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:784 , http://hdl.handle.net/10962/d1003905
- Description: This thesis was born from a concern the researcher had with regard to negative reports in the media emanating from 4 babies that died at Cecilia Makiwane Hospital Peadiatric ICU unit due to power supply failure. The most significant of these negative reports was in 2007 when the Daily Dispatch ran a series of articles regarding what they termed avoidable deaths over the last 14 years. The ease with which staff communicated with the media together with the high absenteeism rate and high turnover was a cause for concern. When the researcher analysed the history of the problem, it immerged from the respondents’ responses that the rationalistion process undertaken by the Eastern Cape Department of Health (ECDoH) was a significant root cause to the problem. The literature review focused on three areas viz.: Organisational Culture, Organisational Change, Foundations of Satisfaction. This focus was used to confine the problem to a manageable project but secondly each of the aspects are interwoven. Routledge (2010) notes that culture is the reflection of the values advocated by a founder or leader by way of his/her day to day actions. This is done by the leader creating a perception or viewpoint that assists the employees to achieve the organisation’s mission, vision and goals. In any organisation change is a constant and it needs to be effectively managed. With government institutions like the East London Hospital Complex (ELHC) directives come from the top and are implemented by an unprepared and untrained leadership and management cadre and clear communication of vision and objective of the desired outcomes never happens. The aim of the research was to: describe the existing Organisational Culture present at ELHC (Perform an organisational diagnosis); describe the impact of change (rationalisation) and to analyze why there was such a high staff turnover. It is clear from the results of the survey conducted that significant dissatisfaction prevailed relating to how the institution was managed. Dissatisfaction amongst the health professionals was general but also specific to the following: leadership and management issues, fairness, remuneration and lack of resources. The recommendations therefore focused on developing management and leadership within the proposal of Dubrin’s model (2001).
- Full Text:
- Authors: Galo, Luntu
- Date: 2012
- Subjects: Medical personnel -- Job satisfaction -- South Africa -- Case studies Medical personnel -- Job stress -- South Africa -- Case studies Medical personnel -- South Africa -- Attitudes -- Case studies Hospitals -- South Africa -- Administration Health services administration -- South Africa Health planning -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:784 , http://hdl.handle.net/10962/d1003905
- Description: This thesis was born from a concern the researcher had with regard to negative reports in the media emanating from 4 babies that died at Cecilia Makiwane Hospital Peadiatric ICU unit due to power supply failure. The most significant of these negative reports was in 2007 when the Daily Dispatch ran a series of articles regarding what they termed avoidable deaths over the last 14 years. The ease with which staff communicated with the media together with the high absenteeism rate and high turnover was a cause for concern. When the researcher analysed the history of the problem, it immerged from the respondents’ responses that the rationalistion process undertaken by the Eastern Cape Department of Health (ECDoH) was a significant root cause to the problem. The literature review focused on three areas viz.: Organisational Culture, Organisational Change, Foundations of Satisfaction. This focus was used to confine the problem to a manageable project but secondly each of the aspects are interwoven. Routledge (2010) notes that culture is the reflection of the values advocated by a founder or leader by way of his/her day to day actions. This is done by the leader creating a perception or viewpoint that assists the employees to achieve the organisation’s mission, vision and goals. In any organisation change is a constant and it needs to be effectively managed. With government institutions like the East London Hospital Complex (ELHC) directives come from the top and are implemented by an unprepared and untrained leadership and management cadre and clear communication of vision and objective of the desired outcomes never happens. The aim of the research was to: describe the existing Organisational Culture present at ELHC (Perform an organisational diagnosis); describe the impact of change (rationalisation) and to analyze why there was such a high staff turnover. It is clear from the results of the survey conducted that significant dissatisfaction prevailed relating to how the institution was managed. Dissatisfaction amongst the health professionals was general but also specific to the following: leadership and management issues, fairness, remuneration and lack of resources. The recommendations therefore focused on developing management and leadership within the proposal of Dubrin’s model (2001).
- Full Text:
A case study of Bigodi Wetland Sanctuary as a community driven Community-Based Natural Resource Management initiative : maintaining livelihoods and wetland health
- Authors: Gosling, Amanda Karen
- Date: 2012
- Subjects: Wetland conservation -- Uganda , Wetland ecology -- Uganda , Natural resources management areas -- Uganda , Rural development -- Uganda
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4752 , http://hdl.handle.net/10962/d1007065 , Wetland conservation -- Uganda , Wetland ecology -- Uganda , Natural resources management areas -- Uganda , Rural development -- Uganda
- Description: Community-Based Natural Resource Management (CBNRM) is considered a win-win approach to reconcile conservation with natural resource use. CBNRM aims to accomplish conservation whilst prioritising development and contributing to poverty alleviation. This study analysed the different components of a CBNRM initiative, Bigodi Wetland Sanctuary (BWS), located in western Uganda. The study was carried out by interviewing the managing committee members (n= 8) as well as local households (n= 68) regarding the manner in which the project works, and the associated benefits and constraints. The main management issues recognised were a lack of monitoring and committee cohesiveness. The information gathered through the household survey enabled the calculation of the value of local livelihood options. This was done on the premise that conservation is better accepted when land users realise the economic value of natural resources. The average annual value of household livelihoods was represented by 30% crop production, 57% natural resource use, and 13% livestock. Lastly, wetland assessments were performed using the WET-Health and WET-EcoServices methodologies from the Wetland Management Series. These assessments indicated that the impacts of local livelihoods on the wetland were currently low but potential issues could arise with the increasing human population density. Ultimately, BWS presents both environmental and social costs and benefits. With a detailed and interdisciplinary method specific recommendations of improvement can be made to reduce such costs and further reconcile the conservation of Bigodi Wetland with local natural resource use..
- Full Text:
- Authors: Gosling, Amanda Karen
- Date: 2012
- Subjects: Wetland conservation -- Uganda , Wetland ecology -- Uganda , Natural resources management areas -- Uganda , Rural development -- Uganda
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4752 , http://hdl.handle.net/10962/d1007065 , Wetland conservation -- Uganda , Wetland ecology -- Uganda , Natural resources management areas -- Uganda , Rural development -- Uganda
- Description: Community-Based Natural Resource Management (CBNRM) is considered a win-win approach to reconcile conservation with natural resource use. CBNRM aims to accomplish conservation whilst prioritising development and contributing to poverty alleviation. This study analysed the different components of a CBNRM initiative, Bigodi Wetland Sanctuary (BWS), located in western Uganda. The study was carried out by interviewing the managing committee members (n= 8) as well as local households (n= 68) regarding the manner in which the project works, and the associated benefits and constraints. The main management issues recognised were a lack of monitoring and committee cohesiveness. The information gathered through the household survey enabled the calculation of the value of local livelihood options. This was done on the premise that conservation is better accepted when land users realise the economic value of natural resources. The average annual value of household livelihoods was represented by 30% crop production, 57% natural resource use, and 13% livestock. Lastly, wetland assessments were performed using the WET-Health and WET-EcoServices methodologies from the Wetland Management Series. These assessments indicated that the impacts of local livelihoods on the wetland were currently low but potential issues could arise with the increasing human population density. Ultimately, BWS presents both environmental and social costs and benefits. With a detailed and interdisciplinary method specific recommendations of improvement can be made to reduce such costs and further reconcile the conservation of Bigodi Wetland with local natural resource use..
- Full Text:
A comparative polarimetric study of the 43 GHz and 86 GHz SiO masers toward the supergiant star VY CMa
- Authors: Richter, Laura
- Date: 2012
- Subjects: Masers Supergiant stars Polarization (Light) Very long baseline interferometry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5454 , http://hdl.handle.net/10962/d1005239
- Description: The aim of this thesis is to perform observational tests of SiO maser polarisation and excitation models, using component-level comparisons of multiple SiO maser transitions in the 43 GHz and 86 GHz bands at milliarcsecond resolution. These observations reqwre very long baseline interferometric imaging with very accurate polarimetric calibration. The supergiant star VY CMa was chosen as the object of this study due to its high SiO maser luminosity, many detected SiO maser lines, and intrinsic scientific interest. Two epochs of full-polarisation VLBA observations of VY CMa were performed. The Epoch 2 observations were reduced using several new data reduction methods developed as part of this work, and designed specifically to improve the accuracy of circular polarisation calibration of spectral-line VLBI observations at millimetre wavelengths. The accuracy is estimated to be better than 1% using these methods. The Epoch 2 images show a concentration of v= l and v=2 J= 1-0 SiO masers to the east and northeast of the assumed stellar position. The v=l J=2-1 masers were more evenly distributed around the star, with a notable lack of emission in the northeast. There is appreciable spatial overlap between these three lines. The nature of the overlap is generally consistent with the predictions of hydrodynamical circumstellar SiO maser simulations. Where the v=l J = 1-0 and J =2-1 features overlap, the v=l J = 2-1 emission is usually considerably weaker. This is not predicted by current hydrodynamical models, but can be explained in the context of collisional pumping in a low density environment. Six observational tests of weak-splitting maser polarisation models were performed, including intercomparisons of linear polarisation in the v=l J=1-0 and J=2-1lines, linear polarisation versus saturation level, linear polarisation versus distance from the star, circular polarisation in the v= l J = 1-0 and J=2-1 lines, circular versus linear polarisation and modeling of ~ 900 electric-vector position angle rotations. The polarisation model tests generally do not support non-Zeeman circular polarisation mechanisms. For the linear polarisation tests, the results are more consistent with models that predict similar linear polarisation across transitions. The scientific importance of these tests is described in detail and avenues for future work are described.
- Full Text:
- Authors: Richter, Laura
- Date: 2012
- Subjects: Masers Supergiant stars Polarization (Light) Very long baseline interferometry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5454 , http://hdl.handle.net/10962/d1005239
- Description: The aim of this thesis is to perform observational tests of SiO maser polarisation and excitation models, using component-level comparisons of multiple SiO maser transitions in the 43 GHz and 86 GHz bands at milliarcsecond resolution. These observations reqwre very long baseline interferometric imaging with very accurate polarimetric calibration. The supergiant star VY CMa was chosen as the object of this study due to its high SiO maser luminosity, many detected SiO maser lines, and intrinsic scientific interest. Two epochs of full-polarisation VLBA observations of VY CMa were performed. The Epoch 2 observations were reduced using several new data reduction methods developed as part of this work, and designed specifically to improve the accuracy of circular polarisation calibration of spectral-line VLBI observations at millimetre wavelengths. The accuracy is estimated to be better than 1% using these methods. The Epoch 2 images show a concentration of v= l and v=2 J= 1-0 SiO masers to the east and northeast of the assumed stellar position. The v=l J=2-1 masers were more evenly distributed around the star, with a notable lack of emission in the northeast. There is appreciable spatial overlap between these three lines. The nature of the overlap is generally consistent with the predictions of hydrodynamical circumstellar SiO maser simulations. Where the v=l J = 1-0 and J =2-1 features overlap, the v=l J = 2-1 emission is usually considerably weaker. This is not predicted by current hydrodynamical models, but can be explained in the context of collisional pumping in a low density environment. Six observational tests of weak-splitting maser polarisation models were performed, including intercomparisons of linear polarisation in the v=l J=1-0 and J=2-1lines, linear polarisation versus saturation level, linear polarisation versus distance from the star, circular polarisation in the v= l J = 1-0 and J=2-1 lines, circular versus linear polarisation and modeling of ~ 900 electric-vector position angle rotations. The polarisation model tests generally do not support non-Zeeman circular polarisation mechanisms. For the linear polarisation tests, the results are more consistent with models that predict similar linear polarisation across transitions. The scientific importance of these tests is described in detail and avenues for future work are described.
- Full Text:
A critical realist exploration of the implementation of a new curriculum in Swaziland
- Authors: Pereira, Liphie
- Date: 2012
- Subjects: Critical realism Education -- Philosophy Critical pedagogy -- Swaziland Curriculum change -- Swaziland Education -- Swaziland Education and state -- Swaziland Education -- Aims and objectives -- Swaziland Critical discourse analysis International General Certificate of Secondary Education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1484 , http://hdl.handle.net/10962/d1003365
- Description: This study offers an in-depth exploration of the conditions from which the implementation of a curriculum called the International General Certificate of Secondary Education (IGCSE), later localised into Swaziland General Certificate of Secondary Education (SGCSE), emerged and the constraining and enabling conditions for the implementation of the new I/SGCSE curriculum. It derives its theoretical foundation from Roy Bhaskar’s critical realism and Margaret Archer’s concept of analytical separability. The study therefore offers explanations about the curriculum change and its implementation that are based on how structural, cultural, and agential mechanisms operating at a deeper level of reality (the intransitive layer of reality or the domain of the real) and existing independently of what we see, know or believe of them (the transitive layer of reality or domains of the actual and empirical) interacted to condition the emergence of I/SGCSE and the way it is implemented. I conduct a critical discourse analysis of relevant literature, I/SGCSE documents and interview data in order to identify those mechanisms that were cultural and also those that were structural and agential. Bernstein’s concepts of classification and framing are used to analyse observation data in order to explore the influence of these mechanisms on the teaching practices of the teachers who took part in the study. Analysis of the data suggests that the change from General Certificate of Education Ordinary Level (GCE O-level) to I/SGCSE was conditioned by inconsistencies between the cultural and structural mechanisms of the Swazi context. Many of the cultural elements of the Swazi context such as the discourses of good citizens, of competitive advantage, and of quality education draw from global discourses which view relations between people from a postmodernist position and therefore support weakly classified and framed pedagogic practices. In contrast, the discourse of morality and many of the structural elements of the Swazi context, such as the pre2006 education system and the Tinkhundla government system, all view reality from a modernist position, therefore supporting strong relations of power and control. The cultural system therefore exerted more influence in conditioning the change from the strongly classified and framed GCE O-level curriculum to the weakly classified and framed I/SGCSE curriculum. Furthermore, the analysis of interview and observation data suggests that inconsistencies between the global discourses and the discourses and structures that teachers confront in their day-to-day lives, together with the decisions teachers made in response to structural constraints, created constraining conditions for the change from GCE O-level to I/SGCSE. The study adds to knowledge on curriculum change and implementation through insights into the enabling and constraining effects of mechanisms operating at a deeper level of reality on curriculum-change decisions and on the ability of teachers to implement curriculum changes. The focus on the deeper level of reality may therefore contribute towards emancipatory knowledge which could be used not only by the Ministry of Education and Training and teachers in Swaziland but also elsewhere to inform future planning, decision making, and practice in relation to curriculum change and implementation.
- Full Text:
- Authors: Pereira, Liphie
- Date: 2012
- Subjects: Critical realism Education -- Philosophy Critical pedagogy -- Swaziland Curriculum change -- Swaziland Education -- Swaziland Education and state -- Swaziland Education -- Aims and objectives -- Swaziland Critical discourse analysis International General Certificate of Secondary Education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1484 , http://hdl.handle.net/10962/d1003365
- Description: This study offers an in-depth exploration of the conditions from which the implementation of a curriculum called the International General Certificate of Secondary Education (IGCSE), later localised into Swaziland General Certificate of Secondary Education (SGCSE), emerged and the constraining and enabling conditions for the implementation of the new I/SGCSE curriculum. It derives its theoretical foundation from Roy Bhaskar’s critical realism and Margaret Archer’s concept of analytical separability. The study therefore offers explanations about the curriculum change and its implementation that are based on how structural, cultural, and agential mechanisms operating at a deeper level of reality (the intransitive layer of reality or the domain of the real) and existing independently of what we see, know or believe of them (the transitive layer of reality or domains of the actual and empirical) interacted to condition the emergence of I/SGCSE and the way it is implemented. I conduct a critical discourse analysis of relevant literature, I/SGCSE documents and interview data in order to identify those mechanisms that were cultural and also those that were structural and agential. Bernstein’s concepts of classification and framing are used to analyse observation data in order to explore the influence of these mechanisms on the teaching practices of the teachers who took part in the study. Analysis of the data suggests that the change from General Certificate of Education Ordinary Level (GCE O-level) to I/SGCSE was conditioned by inconsistencies between the cultural and structural mechanisms of the Swazi context. Many of the cultural elements of the Swazi context such as the discourses of good citizens, of competitive advantage, and of quality education draw from global discourses which view relations between people from a postmodernist position and therefore support weakly classified and framed pedagogic practices. In contrast, the discourse of morality and many of the structural elements of the Swazi context, such as the pre2006 education system and the Tinkhundla government system, all view reality from a modernist position, therefore supporting strong relations of power and control. The cultural system therefore exerted more influence in conditioning the change from the strongly classified and framed GCE O-level curriculum to the weakly classified and framed I/SGCSE curriculum. Furthermore, the analysis of interview and observation data suggests that inconsistencies between the global discourses and the discourses and structures that teachers confront in their day-to-day lives, together with the decisions teachers made in response to structural constraints, created constraining conditions for the change from GCE O-level to I/SGCSE. The study adds to knowledge on curriculum change and implementation through insights into the enabling and constraining effects of mechanisms operating at a deeper level of reality on curriculum-change decisions and on the ability of teachers to implement curriculum changes. The focus on the deeper level of reality may therefore contribute towards emancipatory knowledge which could be used not only by the Ministry of Education and Training and teachers in Swaziland but also elsewhere to inform future planning, decision making, and practice in relation to curriculum change and implementation.
- Full Text:
A framework for the development and measurement of agile enterprise architecture
- Authors: Mthupha, Bokang
- Date: 2012
- Subjects: Management information systems -- Research Industrial management -- Technological innovations -- Research Industrial organization -- Technological innovations -- Research System design
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1147 , http://hdl.handle.net/10962/d1002777
- Description: Enterprise architecture is the high-level design of the entire business, facilitated by enterprise architects. "Agile enterprise architecture" is the term used in enterprise architecture to describe an architecture that caters for future unknowns, enabling change to occur rapidly without undue resource utilization, yet in a controlled manner and with minimal adverse impact. Some enterprise architects still use outdated, rigid approaches to enterprise architecture which are incompatible with today‟s business environment. In addition, there is limited research into methods that can be applied to measure the agility of enterprise architecture. The current environment is such that there is a need for a more agile approach to developing and measuring enterprise architecture. This work will lead to the creation of a Framework for The Development and Measurement of Agile Enterprise Architecture. In support of the main goal of the development of the framework, a literature review will be conducted focusing on the necessary sub-goals of the research. The first sub-goal of the literature review is to develop a comprehensive definition for enterprise architecture (referred to as EA), as well as discover how it is currently practiced. Thereafter, the literature review will investigate a comprehensive definition for agility and research why it is emerging as a critical topic. The next chapter of the literature review will research how agility fits within the context of EA, uncovering a comprehensive definition for agile EA and the best practices in agile EA development. The final chapter of the literature review will investigate suitable measurement techniques that can be used to assess the level of agility of EA. On completion of the literature review, a preliminary framework will be created using the most important contributions from the literature. An empirical study will be conducted to explore the definitions for EA, agility, agile EA, the methods to measure the agility of EA and the concepts for the development of agile EA summarised in the preliminary framework. Data analysis follows an interpretive and qualitative approach based on four case studies through interviews with systems experts in four South African organizations in one province. Each interviewee was interviewed once. The initial interview with a Principal Consultant on Enterprise Strategy Consulting at organisation # 1 formed the basis of an exploratory study; the results of which were used to refine the research instrument and preliminary framework. Thereafter, a more rigorous empirical study focused on interviews with the Chief Architect, Senior Manager in Advisory Services and an Enterprise Architect at organizations 2, 3 and 4 respectively was conducted. The research follows an inductive approach to capture the interpretive experiences of participants and develop theoretical propositions from them. Following the exploratory pilot study it became necessary to make changes to the preliminary framework and initial survey instrument created. Thereafter, the empirical study consisting of the remaining three cases was conducted to test the important aspects of the framework and literature definitions. The analysis of the results of the empirical study prompted further changes to the theoretical framework and definitions created. The interviews conducted with each of the organizations confirmed the factors for agile EA development as well as the effectiveness of the definitions created in the literature review. The research uncovered that the need for a more agile approach to developing EA and a way to measure the level of agility of EA has become more and more significant in organizations. This begins with a better understanding of EA, agility, how agility fits within the context of EA, as well as appropriate methods to measure agility.
- Full Text:
- Authors: Mthupha, Bokang
- Date: 2012
- Subjects: Management information systems -- Research Industrial management -- Technological innovations -- Research Industrial organization -- Technological innovations -- Research System design
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1147 , http://hdl.handle.net/10962/d1002777
- Description: Enterprise architecture is the high-level design of the entire business, facilitated by enterprise architects. "Agile enterprise architecture" is the term used in enterprise architecture to describe an architecture that caters for future unknowns, enabling change to occur rapidly without undue resource utilization, yet in a controlled manner and with minimal adverse impact. Some enterprise architects still use outdated, rigid approaches to enterprise architecture which are incompatible with today‟s business environment. In addition, there is limited research into methods that can be applied to measure the agility of enterprise architecture. The current environment is such that there is a need for a more agile approach to developing and measuring enterprise architecture. This work will lead to the creation of a Framework for The Development and Measurement of Agile Enterprise Architecture. In support of the main goal of the development of the framework, a literature review will be conducted focusing on the necessary sub-goals of the research. The first sub-goal of the literature review is to develop a comprehensive definition for enterprise architecture (referred to as EA), as well as discover how it is currently practiced. Thereafter, the literature review will investigate a comprehensive definition for agility and research why it is emerging as a critical topic. The next chapter of the literature review will research how agility fits within the context of EA, uncovering a comprehensive definition for agile EA and the best practices in agile EA development. The final chapter of the literature review will investigate suitable measurement techniques that can be used to assess the level of agility of EA. On completion of the literature review, a preliminary framework will be created using the most important contributions from the literature. An empirical study will be conducted to explore the definitions for EA, agility, agile EA, the methods to measure the agility of EA and the concepts for the development of agile EA summarised in the preliminary framework. Data analysis follows an interpretive and qualitative approach based on four case studies through interviews with systems experts in four South African organizations in one province. Each interviewee was interviewed once. The initial interview with a Principal Consultant on Enterprise Strategy Consulting at organisation # 1 formed the basis of an exploratory study; the results of which were used to refine the research instrument and preliminary framework. Thereafter, a more rigorous empirical study focused on interviews with the Chief Architect, Senior Manager in Advisory Services and an Enterprise Architect at organizations 2, 3 and 4 respectively was conducted. The research follows an inductive approach to capture the interpretive experiences of participants and develop theoretical propositions from them. Following the exploratory pilot study it became necessary to make changes to the preliminary framework and initial survey instrument created. Thereafter, the empirical study consisting of the remaining three cases was conducted to test the important aspects of the framework and literature definitions. The analysis of the results of the empirical study prompted further changes to the theoretical framework and definitions created. The interviews conducted with each of the organizations confirmed the factors for agile EA development as well as the effectiveness of the definitions created in the literature review. The research uncovered that the need for a more agile approach to developing EA and a way to measure the level of agility of EA has become more and more significant in organizations. This begins with a better understanding of EA, agility, how agility fits within the context of EA, as well as appropriate methods to measure agility.
- Full Text:
A Framework for the Static Analysis of Malware focusing on Signal Processing Techniques
- Zeisberger, Sascha, Irwin, Barry V W
- Authors: Zeisberger, Sascha , Irwin, Barry V W
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427914 , vital:72473 , https://www.researchgate.net/profile/Barry-Ir-win/publication/327622833_A_Framework_for_the_Static_Analysis_of_Mal-ware_focusing_on_Signal_Processing_Techniques/links/5b9a1396a6fdcc59bf8dfc87/A-Framework-for-the-Static-Analysis-of-Malware-focusing-on-Signal-Processing-Techniques.pdf
- Description: The information gathered through conventional static analysis of malicious binaries has become increasingly limited. This is due to the rate at which new malware is being created as well as the increasingly complex methods employed to obfuscating these binaries. This paper discusses the development of a framework to analyse malware using signal processing techniques, the initial iteration of which focuses on common audio processing techniques such as Fourier transforms. The aim of this research is to identify characteristics of malware and the encryption methods used to obfuscate malware. This is achieved through the analysis of their binary structure, potentially providing an additional metric for autonomously fingerprinting malware.
- Full Text:
- Authors: Zeisberger, Sascha , Irwin, Barry V W
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427914 , vital:72473 , https://www.researchgate.net/profile/Barry-Ir-win/publication/327622833_A_Framework_for_the_Static_Analysis_of_Mal-ware_focusing_on_Signal_Processing_Techniques/links/5b9a1396a6fdcc59bf8dfc87/A-Framework-for-the-Static-Analysis-of-Malware-focusing-on-Signal-Processing-Techniques.pdf
- Description: The information gathered through conventional static analysis of malicious binaries has become increasingly limited. This is due to the rate at which new malware is being created as well as the increasingly complex methods employed to obfuscating these binaries. This paper discusses the development of a framework to analyse malware using signal processing techniques, the initial iteration of which focuses on common audio processing techniques such as Fourier transforms. The aim of this research is to identify characteristics of malware and the encryption methods used to obfuscate malware. This is achieved through the analysis of their binary structure, potentially providing an additional metric for autonomously fingerprinting malware.
- Full Text:
A highly selective and sensitive pyridylazo-2-naphthol-poly (acrylic acid) functionalized electrospun nanofiber fluorescence “turn-off” chemosensory system for Ni 2+
- Adewuyi, Sheriff, Ondigo, Dezzline A, Zugle, Ruphino, Tshentu, Zenixole R, Nyokong, Tebello, Torto, Nelson
- Authors: Adewuyi, Sheriff , Ondigo, Dezzline A , Zugle, Ruphino , Tshentu, Zenixole R , Nyokong, Tebello , Torto, Nelson
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246012 , vital:51428 , xlink:href="https://doi.org/10.1039/C2AY25182E"
- Description: A fluorescent nanofiber probe for the determination of Ni2+ was developed via the electrospinning of a covalently functionalized pyridylazo-2-naphthol-poly(acrylic acid) polymer. Fluorescent nanofibers with diameters in the range 230–800 nm were produced with uniformly dispersed fluorophores. The excitation and emission fluorescence were at wavelengths 479 and 557 nm respectively, thereby exhibiting a good Stokes' shift. This Ni2+ probe that employs fluorescence quenching in a solid receptor–fluorophore system exhibited a good correlation between the fluorescence intensity and nickel concentration up to 1.0 μg mL−1 based on the Stern–Volmer mechanism. The probe achieved a detection limit (3δ/S) of 0.07 ng mL−1 and a precision, calculated as a relative standard deviation (RSD) of more than 4% (n = 8). The concentration of Ni2+ in a certified reference material (SEP-3) was found to be 0.8986 μg mL−1, which is significantly comparable with the certified value of 0.8980 μg mL−1. The accuracy of the determinations, expressed as a relative error between the certified and the observed values of certified reference groundwater was ≤0.1%. The versatility of the nanofiber probe was demonstrated by affording simple, rapid and selective detection of Ni2+ in the presence of other competing metal ions by direct analysis, without employing any further sample handling steps.
- Full Text:
- Authors: Adewuyi, Sheriff , Ondigo, Dezzline A , Zugle, Ruphino , Tshentu, Zenixole R , Nyokong, Tebello , Torto, Nelson
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246012 , vital:51428 , xlink:href="https://doi.org/10.1039/C2AY25182E"
- Description: A fluorescent nanofiber probe for the determination of Ni2+ was developed via the electrospinning of a covalently functionalized pyridylazo-2-naphthol-poly(acrylic acid) polymer. Fluorescent nanofibers with diameters in the range 230–800 nm were produced with uniformly dispersed fluorophores. The excitation and emission fluorescence were at wavelengths 479 and 557 nm respectively, thereby exhibiting a good Stokes' shift. This Ni2+ probe that employs fluorescence quenching in a solid receptor–fluorophore system exhibited a good correlation between the fluorescence intensity and nickel concentration up to 1.0 μg mL−1 based on the Stern–Volmer mechanism. The probe achieved a detection limit (3δ/S) of 0.07 ng mL−1 and a precision, calculated as a relative standard deviation (RSD) of more than 4% (n = 8). The concentration of Ni2+ in a certified reference material (SEP-3) was found to be 0.8986 μg mL−1, which is significantly comparable with the certified value of 0.8980 μg mL−1. The accuracy of the determinations, expressed as a relative error between the certified and the observed values of certified reference groundwater was ≤0.1%. The versatility of the nanofiber probe was demonstrated by affording simple, rapid and selective detection of Ni2+ in the presence of other competing metal ions by direct analysis, without employing any further sample handling steps.
- Full Text:
A Mobile Phone Solution to Improve Geographic Mobility
- Miteche, Sacha, Terzoli, Alfredo, Thinyane, Hannah
- Authors: Miteche, Sacha , Terzoli, Alfredo , Thinyane, Hannah
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428423 , vital:72510 , https://www.cs.ru.ac.za/research/g10m4201/docs/SATNACWIP.pdf
- Description: Motor vehicle ride sharing is a popular way of travelling in most coun-tries. Different incentives have made this mode of travelling to exist formally and informally, for example as in carpooling clubs and hitchhik-ing respectively. Advances in Information and Communication Tech-nology (ICT) have facilitated developments of formal Dynamic Ride Sharing (DRS) systems that target mobile devices. These are seen as solutions to people’s preference of flexible ride sharing services. In de-veloping countries, hitchhiking is a common technique for ride sharing travels. This paper describes a proposal to develop a DRS system that primarily targets mobile phone users in South Africa for informal ride sharing methods done in hitchhiking.
- Full Text:
- Authors: Miteche, Sacha , Terzoli, Alfredo , Thinyane, Hannah
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428423 , vital:72510 , https://www.cs.ru.ac.za/research/g10m4201/docs/SATNACWIP.pdf
- Description: Motor vehicle ride sharing is a popular way of travelling in most coun-tries. Different incentives have made this mode of travelling to exist formally and informally, for example as in carpooling clubs and hitchhik-ing respectively. Advances in Information and Communication Tech-nology (ICT) have facilitated developments of formal Dynamic Ride Sharing (DRS) systems that target mobile devices. These are seen as solutions to people’s preference of flexible ride sharing services. In de-veloping countries, hitchhiking is a common technique for ride sharing travels. This paper describes a proposal to develop a DRS system that primarily targets mobile phone users in South Africa for informal ride sharing methods done in hitchhiking.
- Full Text:
A process-genre approach to teaching argumentative writing to grade nine learners
- Authors: Elson, Jillian Margaret
- Date: 2012
- Subjects: English language -- Rhetoric -- Study and teaching (Secondary) English language -- Writing -- Study and teaching (Secondary) Written communication
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1714 , http://hdl.handle.net/10962/d1003597
- Description: This action research study aimed to improve teaching and learning of argumentative writing through a process-genre approach. Learners were carefully guided through the processes of writing the argumentative genre, with the focus being on teaching of the genre and on the structural conventions of writing arguments. Participants were a class of grade nine learners who speak English as a first language. They were chosen for this study as Grade Nine is a crucial year for writing development before learners enter the senior phase and are met with heightened expectations in the curriculum, that often they struggle to meet, as their writing has not been sufficiently developed to an academic level. The focus of writing in Grade Nine is on narrative and prose, so this writing intervention, in which a teaching module was developed in collaboration with the 1eamers, aimed to broaden their writing skills and provide them with a head start in leaming the fine art of argumentation, as this is a useful skill to acquire for purposes even beyond the classroom. Genre theorists advocate the importance of teaching genres to leamers at a young age, as it allows them access into different communities of discourse, as they become aware and understand the conventions held by a patiicular community, and realize the purpose of different styles of writing for effectively communicating, which prepares them to meet the expectations of their audience. Teaching the structures of different genres therefore allows the writer, and the audience, a framework for understanding the text. The process approach has been widely used by educators as it focuses on explicit teaching of writing processes that are fundamental to leamers' development in writing. Learners need to be carefully guided from the initial stages, to the more complex stages (especially in argumentative writing which has been deemed the most complex genre for learners to master) in order to understand the complexities of constructing an essay in a cohesive way, as they need to consider multiple aspects of writing, such as the linguistic features, rhetorical features and structural features of the genre and unify them into a sound argument. This takes time, practice and revision, and extensive feedback is required. The process-genre approach proved to be successful in this study, as leamers showed remarkable improvements in their writing from the initial stages of writing to the final drafts of their essays. The findings revealed that explicit teaching of genres and structural elements of writing is vital for ensuring learners' development. Learners require modelling of the genre, scaffolding and careful guidance through step-by-step processes in order to build confidence and express their ideas effectively in written text. The findings indicate the relevance of using the process-genre approach for teaching and learning and that teaching and learning writing is indeed a process that needs more time and practice that is cUiTently allocated in the curriculum.
- Full Text:
- Authors: Elson, Jillian Margaret
- Date: 2012
- Subjects: English language -- Rhetoric -- Study and teaching (Secondary) English language -- Writing -- Study and teaching (Secondary) Written communication
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1714 , http://hdl.handle.net/10962/d1003597
- Description: This action research study aimed to improve teaching and learning of argumentative writing through a process-genre approach. Learners were carefully guided through the processes of writing the argumentative genre, with the focus being on teaching of the genre and on the structural conventions of writing arguments. Participants were a class of grade nine learners who speak English as a first language. They were chosen for this study as Grade Nine is a crucial year for writing development before learners enter the senior phase and are met with heightened expectations in the curriculum, that often they struggle to meet, as their writing has not been sufficiently developed to an academic level. The focus of writing in Grade Nine is on narrative and prose, so this writing intervention, in which a teaching module was developed in collaboration with the 1eamers, aimed to broaden their writing skills and provide them with a head start in leaming the fine art of argumentation, as this is a useful skill to acquire for purposes even beyond the classroom. Genre theorists advocate the importance of teaching genres to leamers at a young age, as it allows them access into different communities of discourse, as they become aware and understand the conventions held by a patiicular community, and realize the purpose of different styles of writing for effectively communicating, which prepares them to meet the expectations of their audience. Teaching the structures of different genres therefore allows the writer, and the audience, a framework for understanding the text. The process approach has been widely used by educators as it focuses on explicit teaching of writing processes that are fundamental to leamers' development in writing. Learners need to be carefully guided from the initial stages, to the more complex stages (especially in argumentative writing which has been deemed the most complex genre for learners to master) in order to understand the complexities of constructing an essay in a cohesive way, as they need to consider multiple aspects of writing, such as the linguistic features, rhetorical features and structural features of the genre and unify them into a sound argument. This takes time, practice and revision, and extensive feedback is required. The process-genre approach proved to be successful in this study, as leamers showed remarkable improvements in their writing from the initial stages of writing to the final drafts of their essays. The findings revealed that explicit teaching of genres and structural elements of writing is vital for ensuring learners' development. Learners require modelling of the genre, scaffolding and careful guidance through step-by-step processes in order to build confidence and express their ideas effectively in written text. The findings indicate the relevance of using the process-genre approach for teaching and learning and that teaching and learning writing is indeed a process that needs more time and practice that is cUiTently allocated in the curriculum.
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A reflection on research design and methodologies used in the social learning literature
- Rodela, Romina, Cundill, Georgina, Wals, Arjen
- Authors: Rodela, Romina , Cundill, Georgina , Wals, Arjen
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/436584 , vital:73284 , ISBN 978-1-919991-81-8 , 10.13140/2.1.1855.3285
- Description: This paper reviews the social learning research literature related to natu-ral resources management. It provides an overview of the social learning discourse and then comments on methodologies used by social learning researchers. The present study is part of an activity that looked at the so-cial learning methodological agenda. As such it is a companion study to the analysis reported in Rodela, Cundill and Wals (under review) where aspects of knowledge production and validation in social learning re-search were considered. The present analysis adds to this a deconstruc-tion of the research designs used and a reflection on methodologies that can best support the study of learning processes in a natural resource management context.
- Full Text:
- Authors: Rodela, Romina , Cundill, Georgina , Wals, Arjen
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/436584 , vital:73284 , ISBN 978-1-919991-81-8 , 10.13140/2.1.1855.3285
- Description: This paper reviews the social learning research literature related to natu-ral resources management. It provides an overview of the social learning discourse and then comments on methodologies used by social learning researchers. The present study is part of an activity that looked at the so-cial learning methodological agenda. As such it is a companion study to the analysis reported in Rodela, Cundill and Wals (under review) where aspects of knowledge production and validation in social learning re-search were considered. The present analysis adds to this a deconstruc-tion of the research designs used and a reflection on methodologies that can best support the study of learning processes in a natural resource management context.
- Full Text:
A review of the alderfly genus Leptosialis Esben-Petersen (Megaloptera, Sialidae) with description of a new species from South Africa
- Price, Benjamin W, Liu, Xingyue, de Moor, Ferdy C, Villet, Martin H
- Authors: Price, Benjamin W , Liu, Xingyue , de Moor, Ferdy C , Villet, Martin H
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441461 , vital:73891 , https://zookeys.pensoft.net/articles.php?id=2856
- Description: The monotypic South African alderfly genus Leptosialis Esben-Petersen, 1920 is reviewed and Leptosialis africana Esben-Petersen, 1920 is redescribed. In the process a new species of alderfly Leptosialis necopinata sp. n. from the Eastern Cape and KwaZulu-Natal provinces of South Africa is recognised and described. Within Sialidae the new species most closely resembles Leptosialis africana. A key to the two species of Leptosialis using both adult and larval characters is provided.
- Full Text:
- Authors: Price, Benjamin W , Liu, Xingyue , de Moor, Ferdy C , Villet, Martin H
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441461 , vital:73891 , https://zookeys.pensoft.net/articles.php?id=2856
- Description: The monotypic South African alderfly genus Leptosialis Esben-Petersen, 1920 is reviewed and Leptosialis africana Esben-Petersen, 1920 is redescribed. In the process a new species of alderfly Leptosialis necopinata sp. n. from the Eastern Cape and KwaZulu-Natal provinces of South Africa is recognised and described. Within Sialidae the new species most closely resembles Leptosialis africana. A key to the two species of Leptosialis using both adult and larval characters is provided.
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A search for coherence: Social learning in natural resource management
- Cundill, Georgina, Rodela, Romina
- Authors: Cundill, Georgina , Rodela, Romina
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/436597 , vital:73285 , ISBN 978-1-919991-81-8 , https://transformativelearning.education/wp-content/uploads/2013/01/reviews-on-social-learning-literature.pdf
- Description: This paper presents the results of a review process that sought to disen-tangle the different ways in which social learning is conceptualised in nat-ural resource management. We begin with an historical review that seeks to reveal the roots of social learning theory in natural resource manage-ment. Based on this analysis, we develop typologies of statements about the processes that support social learning, and the outcomes of these processes. We then conduct a systematic review of the literature to as-sess the extent to which there is an emerging consensus around these typologies. We conclude that a key source of the confusion currently prevalent in the literature, stems from the fact that the same term is used to refer to quite different processes, which have different outcomes as their goal. To find our way out of the current confusion in the literature, researchers must be explicit about the definitions that they adopt for so-cial learning, and locate these definitions within the historical develop-ment of thinking around social learning in this field. Active debate about appropriate definitions for social learning, based on empirical studies and experience, should form the basis of this field of research in the coming years.
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- Authors: Cundill, Georgina , Rodela, Romina
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/436597 , vital:73285 , ISBN 978-1-919991-81-8 , https://transformativelearning.education/wp-content/uploads/2013/01/reviews-on-social-learning-literature.pdf
- Description: This paper presents the results of a review process that sought to disen-tangle the different ways in which social learning is conceptualised in nat-ural resource management. We begin with an historical review that seeks to reveal the roots of social learning theory in natural resource manage-ment. Based on this analysis, we develop typologies of statements about the processes that support social learning, and the outcomes of these processes. We then conduct a systematic review of the literature to as-sess the extent to which there is an emerging consensus around these typologies. We conclude that a key source of the confusion currently prevalent in the literature, stems from the fact that the same term is used to refer to quite different processes, which have different outcomes as their goal. To find our way out of the current confusion in the literature, researchers must be explicit about the definitions that they adopt for so-cial learning, and locate these definitions within the historical develop-ment of thinking around social learning in this field. Active debate about appropriate definitions for social learning, based on empirical studies and experience, should form the basis of this field of research in the coming years.
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A South African perspective on the tax implications of virtual asset accumulation and transactions stemming from persistent virtual worlds
- Authors: Haupt, Alexander
- Date: 2012
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:884 , http://hdl.handle.net/10962/d1001638
- Description: Massively multiplayer online role-playing games are growing in popularity with millions of people participating in these persistent online environments on a daily basis. Accompanying the ever-increasing subscription numbers is an increase in real money trade transactions stemming from these game worlds. The research question to be addressed in this thesis is whether transactions stemming from virtual worlds have real-world taxation consequences. The goal of this research is to determine the taxability of virtual assets obtained in structured as well as unstructured virtual environments and to attempt to establish the differences between capital and revenue receipts in these virtual realms, taking into account the nature of a receipt. The general deduction formula is applied to establish the deductibility of expenditure incurred whilst participating in these virtual environments. Sundry matters such as Value-Added Tax, donations tax, the withholding tax on gambling gains and tax avoidance will also be addressed. The methodology adopted for the research could best be described as interpretative, aimed at analysing and interpreting the relationship between real world taxes and persistent virtual worlds and the transactions that stem from participation therein. The research is based purely on documentary evidence. After applying relevant tax legislation to virtual economies it became evident that merely because virtual assets only exist in virtual reality does not necessarily preclude them real world tax consequences. It was concluded, however, that it is not practical for the South African Revenue Service to monitor all virtual world transactions or for participant taxpayers to calculate the real world value of each and every asset acquired in-world. As a result, it was concluded that real world tax consequences should only be applied in situations where participants actually convert their virtual assets into real world currency.
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- Authors: Haupt, Alexander
- Date: 2012
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:884 , http://hdl.handle.net/10962/d1001638
- Description: Massively multiplayer online role-playing games are growing in popularity with millions of people participating in these persistent online environments on a daily basis. Accompanying the ever-increasing subscription numbers is an increase in real money trade transactions stemming from these game worlds. The research question to be addressed in this thesis is whether transactions stemming from virtual worlds have real-world taxation consequences. The goal of this research is to determine the taxability of virtual assets obtained in structured as well as unstructured virtual environments and to attempt to establish the differences between capital and revenue receipts in these virtual realms, taking into account the nature of a receipt. The general deduction formula is applied to establish the deductibility of expenditure incurred whilst participating in these virtual environments. Sundry matters such as Value-Added Tax, donations tax, the withholding tax on gambling gains and tax avoidance will also be addressed. The methodology adopted for the research could best be described as interpretative, aimed at analysing and interpreting the relationship between real world taxes and persistent virtual worlds and the transactions that stem from participation therein. The research is based purely on documentary evidence. After applying relevant tax legislation to virtual economies it became evident that merely because virtual assets only exist in virtual reality does not necessarily preclude them real world tax consequences. It was concluded, however, that it is not practical for the South African Revenue Service to monitor all virtual world transactions or for participant taxpayers to calculate the real world value of each and every asset acquired in-world. As a result, it was concluded that real world tax consequences should only be applied in situations where participants actually convert their virtual assets into real world currency.
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A spatial and temporal analysis of the changes in alien macrophyte communities and a baseline assessment of the macroinvertebrates associated with Eurasian watermilfoil, Myriophyllum spicatum L. (Haloragaceae) in the Vaal River
- Authors: Fordham, Colin Justin
- Date: 2012
- Subjects: Water hyacinth -- Control -- South Africa , Aquatic weeds -- Control -- South Africa , Eurasian watermilfoil -- South Africa , Water quality management -- South Africa , Freshwater invertebrates -- Ecology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5767 , http://hdl.handle.net/10962/d1005455 , Water hyacinth -- Control -- South Africa , Aquatic weeds -- Control -- South Africa , Eurasian watermilfoil -- South Africa , Water quality management -- South Africa , Freshwater invertebrates -- Ecology -- South Africa
- Description: The majority of South Africa’s fresh water (lotic and lentic), is eutrophic and this has resulted in water hyacinth, Eichhornia crassipes (C.Mart.) Solms. (Pontederiaceae) becoming South Africa’s most damaging aquatic macrophyte. Recently however, concerns have also been voiced over the presence of highly invasive submerged macrophyte species, such as Eurasian water-milfoil, Myriophyllum spicatum L. (Haloragaceae) in the Vaal River. Interaction studies between floating and submerged macrophytes have shown that floating macrophyte dominance restricts light penetration into the water column shading out submerged macrophytes while submerged macrophyte dominance reduces nutrient availability in the water column limiting floating macrophyte growth. This cycle ensures that these species cannot coexist in the same habitat for extended periods of time. The aims of this thesis were to: 1. Investigate changes in the historical and current macrophyte dominance in the Vaal River 2. Determine whether these changes could be attributed to stochastic events, such as floods and herbicide control measures. 3. The physio-chemical conditions of the water column, and whether pressure from herbivory by macroinvertebrates had possibly influenced Eurasian water-milfoil’s ability to dominate. Spatial and temporal analysis of satellite imagery revealed that water hyacinth and submerged macrophyte species dominated different regions of the study area over different periods of time from 2006 to 2010. This was significantly correlated with nitrate concentrations of the water column. One of the lower Vaal River Water Management Areas (WMA) had changed from a water hyacinth dominated state in 2006 to an alternative submerged macrophyte dominated stable state in 2008. It was concluded that this change could be attributed to: a stochastic flooding event in 2006; perturbation from integrated control measures implemented against water hyacinth; and low nitrate concentrations of the WMA. The lack of any substantial macroinvertebrate herbivory pressure or control measures implemented against Eurasian water-milfoil, compared to similar surveys conducted in the U.S.A. and its native range in Eurasia was shown to contribute to its dominance. Future successful integrated control programmes, including biological control against Eurasian water-milfoil, could provide the perturbation required to restore the ecosystem. However, without the reduction in nitrate concentration levels, water hyacinth will remain the dominant stable state of the rest of the Vaal River.
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- Authors: Fordham, Colin Justin
- Date: 2012
- Subjects: Water hyacinth -- Control -- South Africa , Aquatic weeds -- Control -- South Africa , Eurasian watermilfoil -- South Africa , Water quality management -- South Africa , Freshwater invertebrates -- Ecology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5767 , http://hdl.handle.net/10962/d1005455 , Water hyacinth -- Control -- South Africa , Aquatic weeds -- Control -- South Africa , Eurasian watermilfoil -- South Africa , Water quality management -- South Africa , Freshwater invertebrates -- Ecology -- South Africa
- Description: The majority of South Africa’s fresh water (lotic and lentic), is eutrophic and this has resulted in water hyacinth, Eichhornia crassipes (C.Mart.) Solms. (Pontederiaceae) becoming South Africa’s most damaging aquatic macrophyte. Recently however, concerns have also been voiced over the presence of highly invasive submerged macrophyte species, such as Eurasian water-milfoil, Myriophyllum spicatum L. (Haloragaceae) in the Vaal River. Interaction studies between floating and submerged macrophytes have shown that floating macrophyte dominance restricts light penetration into the water column shading out submerged macrophytes while submerged macrophyte dominance reduces nutrient availability in the water column limiting floating macrophyte growth. This cycle ensures that these species cannot coexist in the same habitat for extended periods of time. The aims of this thesis were to: 1. Investigate changes in the historical and current macrophyte dominance in the Vaal River 2. Determine whether these changes could be attributed to stochastic events, such as floods and herbicide control measures. 3. The physio-chemical conditions of the water column, and whether pressure from herbivory by macroinvertebrates had possibly influenced Eurasian water-milfoil’s ability to dominate. Spatial and temporal analysis of satellite imagery revealed that water hyacinth and submerged macrophyte species dominated different regions of the study area over different periods of time from 2006 to 2010. This was significantly correlated with nitrate concentrations of the water column. One of the lower Vaal River Water Management Areas (WMA) had changed from a water hyacinth dominated state in 2006 to an alternative submerged macrophyte dominated stable state in 2008. It was concluded that this change could be attributed to: a stochastic flooding event in 2006; perturbation from integrated control measures implemented against water hyacinth; and low nitrate concentrations of the WMA. The lack of any substantial macroinvertebrate herbivory pressure or control measures implemented against Eurasian water-milfoil, compared to similar surveys conducted in the U.S.A. and its native range in Eurasia was shown to contribute to its dominance. Future successful integrated control programmes, including biological control against Eurasian water-milfoil, could provide the perturbation required to restore the ecosystem. However, without the reduction in nitrate concentration levels, water hyacinth will remain the dominant stable state of the rest of the Vaal River.
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A structural and functional specification of a SCIM for service interaction management and personalisation in the IMS
- Authors: Tsietsi, Mosiuoa Jeremia
- Date: 2012
- Subjects: Internet Protocol multimedia subsystem , Internet Protocol multimedia subsystem -- Specifications , Long-Term Evolution (Telecommunications) , European Telecommunications Standards Institute , Wireless communication systems , Multimedia communications
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4606 , http://hdl.handle.net/10962/d1004864 , Internet Protocol multimedia subsystem , Internet Protocol multimedia subsystem -- Specifications , Long-Term Evolution (Telecommunications) , European Telecommunications Standards Institute , Wireless communication systems , Multimedia communications
- Description: The Internet Protocol Multimedia Subsystem (IMS) is a component of the 3G mobile network that has been specified by standards development organisations such as the 3GPP (3rd Generation Partnership Project) and ETSI (European Telecommunication Standards Institute). IMS seeks to guarantee that the telecommunication network of the future provides subscribers with seamless access to services across disparate networks. In order to achieve this, it defines a service architecture that hosts application servers that provide subscribers with value added services. Typically, an application server bundles all the functionality it needs to execute the services it delivers, however this view is currently being challenged. It is now thought that services should be synthesised from simple building blocks called service capabilities. This decomposition would facilitate the re-use of service capabilities across multiple services and would support the creation of new services that could not have originally been conceived. The shift from monolithic services to those built from service capabilities poses a challenge to the current service model in IMS. To accommodate this, the 3GPP has defined an entity known as a service capability interaction manager (SCIM) that would be responsible for managing the interactions between service capabilities in order to realise complex services. Some of these interactions could potentially lead to undesirable results, which the SCIM must work to avoid. As an added requirement, it is believed that the network should allow policies to be applied to network services which the SCIM should be responsible for enforcing. At the time of writing, the functional and structural architecture of the SCIM has not yet been standardised. This thesis explores the current serv ice architecture of the IMS in detail. Proposals that address the structure and functions of the SCIM are carefully compared and contrasted. This investigation leads to the presentation of key aspects of the SCIM, and provides solutions that explain how it should interact with service capabilities, manage undesirable interactions and factor user and network operator policies into its execution model. A modified design of the IMS service layer that embeds the SCIM is subsequently presented and described. The design uses existing IMS protocols and requires no change in the behaviour of the standard IMS entities. In order to develop a testbed for experimental verification of the design, the identification of suitable software platforms was required. This thesis presents some of the most popular platforms currently used by developers such as the Open IMS Core and OpenSER, as well as an open source, Java-based, multimedia communication platform called Mobicents. As a precursor to the development of the SCIM, a converged multimedia service is presented that describes how a video streaming application that is leveraged by a web portal was implemented for an IMS testbed using Mobicents components. The Mobicents SIP Servlets container was subsequently used to model an initial prototype of the SCIM, using a mUlti-component telephony service to illustrate the proposed service execution model. The design focuses on SIP-based services only, but should also work for other types of IMS application servers as well.
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- Authors: Tsietsi, Mosiuoa Jeremia
- Date: 2012
- Subjects: Internet Protocol multimedia subsystem , Internet Protocol multimedia subsystem -- Specifications , Long-Term Evolution (Telecommunications) , European Telecommunications Standards Institute , Wireless communication systems , Multimedia communications
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4606 , http://hdl.handle.net/10962/d1004864 , Internet Protocol multimedia subsystem , Internet Protocol multimedia subsystem -- Specifications , Long-Term Evolution (Telecommunications) , European Telecommunications Standards Institute , Wireless communication systems , Multimedia communications
- Description: The Internet Protocol Multimedia Subsystem (IMS) is a component of the 3G mobile network that has been specified by standards development organisations such as the 3GPP (3rd Generation Partnership Project) and ETSI (European Telecommunication Standards Institute). IMS seeks to guarantee that the telecommunication network of the future provides subscribers with seamless access to services across disparate networks. In order to achieve this, it defines a service architecture that hosts application servers that provide subscribers with value added services. Typically, an application server bundles all the functionality it needs to execute the services it delivers, however this view is currently being challenged. It is now thought that services should be synthesised from simple building blocks called service capabilities. This decomposition would facilitate the re-use of service capabilities across multiple services and would support the creation of new services that could not have originally been conceived. The shift from monolithic services to those built from service capabilities poses a challenge to the current service model in IMS. To accommodate this, the 3GPP has defined an entity known as a service capability interaction manager (SCIM) that would be responsible for managing the interactions between service capabilities in order to realise complex services. Some of these interactions could potentially lead to undesirable results, which the SCIM must work to avoid. As an added requirement, it is believed that the network should allow policies to be applied to network services which the SCIM should be responsible for enforcing. At the time of writing, the functional and structural architecture of the SCIM has not yet been standardised. This thesis explores the current serv ice architecture of the IMS in detail. Proposals that address the structure and functions of the SCIM are carefully compared and contrasted. This investigation leads to the presentation of key aspects of the SCIM, and provides solutions that explain how it should interact with service capabilities, manage undesirable interactions and factor user and network operator policies into its execution model. A modified design of the IMS service layer that embeds the SCIM is subsequently presented and described. The design uses existing IMS protocols and requires no change in the behaviour of the standard IMS entities. In order to develop a testbed for experimental verification of the design, the identification of suitable software platforms was required. This thesis presents some of the most popular platforms currently used by developers such as the Open IMS Core and OpenSER, as well as an open source, Java-based, multimedia communication platform called Mobicents. As a precursor to the development of the SCIM, a converged multimedia service is presented that describes how a video streaming application that is leveraged by a web portal was implemented for an IMS testbed using Mobicents components. The Mobicents SIP Servlets container was subsequently used to model an initial prototype of the SCIM, using a mUlti-component telephony service to illustrate the proposed service execution model. The design focuses on SIP-based services only, but should also work for other types of IMS application servers as well.
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A study of four-dimensional oscillator groups and the associated left-invariant control affine systems
- Authors: Biggs, Rory
- Date: 2012
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164941 , vital:41186
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Department of Mathematics, 2012
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- Authors: Biggs, Rory
- Date: 2012
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164941 , vital:41186
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Department of Mathematics, 2012
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