Data-centric security : towards a utopian model for protecting corporate data on mobile devices
- Authors: Mayisela, Simphiwe Hector
- Date: 2014
- Subjects: Computer security , Computer networks -- Security measures , Business enterprises -- Computer networks -- Security measures , Mobile computing -- Security measures , Mobile communication systems -- Security measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4688 , http://hdl.handle.net/10962/d1011094 , Computer security , Computer networks -- Security measures , Business enterprises -- Computer networks -- Security measures , Mobile computing -- Security measures , Mobile communication systems -- Security measures
- Description: Data-centric security is significant in understanding, assessing and mitigating the various risks and impacts of sharing information outside corporate boundaries. Information generally leaves corporate boundaries through mobile devices. Mobile devices continue to evolve as multi-functional tools for everyday life, surpassing their initial intended use. This added capability and increasingly extensive use of mobile devices does not come without a degree of risk - hence the need to guard and protect information as it exists beyond the corporate boundaries and throughout its lifecycle. Literature on existing models crafted to protect data, rather than infrastructure in which the data resides, is reviewed. Technologies that organisations have implemented to adopt the data-centric model are studied. A utopian model that takes into account the shortcomings of existing technologies and deficiencies of common theories is proposed. Two sets of qualitative studies are reported; the first is a preliminary online survey to assess the ubiquity of mobile devices and extent of technology adoption towards implementation of data-centric model; and the second comprises of a focus survey and expert interviews pertaining on technologies that organisations have implemented to adopt the data-centric model. The latter study revealed insufficient data at the time of writing for the results to be statistically significant; however; indicative trends supported the assertions documented in the literature review. The question that this research answers is whether or not current technology implementations designed to mitigate risks from mobile devices, actually address business requirements. This research question, answered through these two sets qualitative studies, discovered inconsistencies between the technology implementations and business requirements. The thesis concludes by proposing a realistic model, based on the outcome of the qualitative study, which bridges the gap between the technology implementations and business requirements. Future work which could perhaps be conducted in light of the findings and the comments from this research is also considered.
- Full Text:
- Date Issued: 2014
- Authors: Mayisela, Simphiwe Hector
- Date: 2014
- Subjects: Computer security , Computer networks -- Security measures , Business enterprises -- Computer networks -- Security measures , Mobile computing -- Security measures , Mobile communication systems -- Security measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4688 , http://hdl.handle.net/10962/d1011094 , Computer security , Computer networks -- Security measures , Business enterprises -- Computer networks -- Security measures , Mobile computing -- Security measures , Mobile communication systems -- Security measures
- Description: Data-centric security is significant in understanding, assessing and mitigating the various risks and impacts of sharing information outside corporate boundaries. Information generally leaves corporate boundaries through mobile devices. Mobile devices continue to evolve as multi-functional tools for everyday life, surpassing their initial intended use. This added capability and increasingly extensive use of mobile devices does not come without a degree of risk - hence the need to guard and protect information as it exists beyond the corporate boundaries and throughout its lifecycle. Literature on existing models crafted to protect data, rather than infrastructure in which the data resides, is reviewed. Technologies that organisations have implemented to adopt the data-centric model are studied. A utopian model that takes into account the shortcomings of existing technologies and deficiencies of common theories is proposed. Two sets of qualitative studies are reported; the first is a preliminary online survey to assess the ubiquity of mobile devices and extent of technology adoption towards implementation of data-centric model; and the second comprises of a focus survey and expert interviews pertaining on technologies that organisations have implemented to adopt the data-centric model. The latter study revealed insufficient data at the time of writing for the results to be statistically significant; however; indicative trends supported the assertions documented in the literature review. The question that this research answers is whether or not current technology implementations designed to mitigate risks from mobile devices, actually address business requirements. This research question, answered through these two sets qualitative studies, discovered inconsistencies between the technology implementations and business requirements. The thesis concludes by proposing a realistic model, based on the outcome of the qualitative study, which bridges the gap between the technology implementations and business requirements. Future work which could perhaps be conducted in light of the findings and the comments from this research is also considered.
- Full Text:
- Date Issued: 2014
An investigation of online threat awareness and behaviour patterns amongst secondary school learners
- Authors: Irwin, Michael Padric
- Date: 2013 , 2013-04-29
- Subjects: Computer security -- South Africa -- Grahamstown , Risk perception -- South Africa -- Grahamstown , High school students -- South Africa -- Grahamstown , Communication -- Sex differences -- South Africa -- Grahamstown , Internet and teenagers -- South Africa -- Grahamstown , Internet and teenagers -- Risk assessment -- South Africa -- Grahamstown , Internet -- Safety measures -- South Africa -- Grahamstown , Online social networks -- Social aspects -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4576 , http://hdl.handle.net/10962/d1002965 , Computer security -- South Africa -- Grahamstown , Risk perception -- South Africa -- Grahamstown , High school students -- South Africa -- Grahamstown , Communication -- Sex differences -- South Africa -- Grahamstown , Internet and teenagers -- South Africa -- Grahamstown , Internet and teenagers -- Risk assessment -- South Africa -- Grahamstown , Internet -- Safety measures -- South Africa -- Grahamstown , Online social networks -- Social aspects -- South Africa -- Grahamstown
- Description: The research area of this work is online threat awareness within an information security context. The research was carried out on secondary school learners at boarding schools in Grahamstown. The participating learners were in Grades 8 to 12. The goals of the research included determining the actual levels of awareness, the difference between these and self-perceived levels of the participants, the assessment of risk in terms of online behaviour, and the determination of any gender differences in the answers provided by the respondents. A review of relevant literature and similar studies was carried out, and data was collected from the participating schools via an online questionnaire. This data was analysed and discussed within the frameworks of awareness of threats, online privacy social media, sexting, cyberbullying and password habits. The concepts of information security and online privacy are present throughout these discussion chapters, providing the themes for linking the discussion points together. The results of this research show that the respondents have a high level of risk. This is due to the gaps identified in actual awareness and perception, as well as the exhibition of online behaviour patterns that are considered high risk. A strong need for the construction and adoption of threat awareness programmes by these and other schools is identified, as are areas of particular need for inclusion in such programmes. Some gender differences are present, but not to the extent that, there is as significant difference between male and female respondents in terms of overall awareness, knowledge and behaviour.
- Full Text:
- Date Issued: 2013
An investigation of online threat awareness and behaviour patterns amongst secondary school learners
- Authors: Irwin, Michael Padric
- Date: 2013 , 2013-04-29
- Subjects: Computer security -- South Africa -- Grahamstown , Risk perception -- South Africa -- Grahamstown , High school students -- South Africa -- Grahamstown , Communication -- Sex differences -- South Africa -- Grahamstown , Internet and teenagers -- South Africa -- Grahamstown , Internet and teenagers -- Risk assessment -- South Africa -- Grahamstown , Internet -- Safety measures -- South Africa -- Grahamstown , Online social networks -- Social aspects -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4576 , http://hdl.handle.net/10962/d1002965 , Computer security -- South Africa -- Grahamstown , Risk perception -- South Africa -- Grahamstown , High school students -- South Africa -- Grahamstown , Communication -- Sex differences -- South Africa -- Grahamstown , Internet and teenagers -- South Africa -- Grahamstown , Internet and teenagers -- Risk assessment -- South Africa -- Grahamstown , Internet -- Safety measures -- South Africa -- Grahamstown , Online social networks -- Social aspects -- South Africa -- Grahamstown
- Description: The research area of this work is online threat awareness within an information security context. The research was carried out on secondary school learners at boarding schools in Grahamstown. The participating learners were in Grades 8 to 12. The goals of the research included determining the actual levels of awareness, the difference between these and self-perceived levels of the participants, the assessment of risk in terms of online behaviour, and the determination of any gender differences in the answers provided by the respondents. A review of relevant literature and similar studies was carried out, and data was collected from the participating schools via an online questionnaire. This data was analysed and discussed within the frameworks of awareness of threats, online privacy social media, sexting, cyberbullying and password habits. The concepts of information security and online privacy are present throughout these discussion chapters, providing the themes for linking the discussion points together. The results of this research show that the respondents have a high level of risk. This is due to the gaps identified in actual awareness and perception, as well as the exhibition of online behaviour patterns that are considered high risk. A strong need for the construction and adoption of threat awareness programmes by these and other schools is identified, as are areas of particular need for inclusion in such programmes. Some gender differences are present, but not to the extent that, there is as significant difference between male and female respondents in terms of overall awareness, knowledge and behaviour.
- Full Text:
- Date Issued: 2013
The dispersal of African wild dogs (Lycaon Pictus) from protected areas in the Northern KwaZulu‐Natal Province, South Africa.
- Whittington‐Jones, Brendan Mark
- Authors: Whittington‐Jones, Brendan Mark
- Date: 2012
- Subjects: African wild dog , African wild dog -- Conservation -- South Africa -- KwazuluNatal , African wild dog -- Dispersal -- South Africa -- KwaZulu-Natal , African wild dog -- Effect of human beings on -- South Africa -- KwaZulu Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5893 , http://hdl.handle.net/10962/d1013414
- Description: The number of African wild dogs Lycaon pictus in Northern KwaZulu‐Natal, South Africa has increased substantially over the last six years. This is largely due to a managed metapopulation approach of introductions onto protected areas and private game reserves since 1998. Because of the increasing wild dog population, the likelihood of rural communities surrounding protected areas encountering dispersing wild dogs in northern KwaZulu‐Natal has also increased. Resident wild dog populations currently occur in Hluhluwe‐iMfolozi Park (HiP), Mkhuze Game Reserve (MGR) of Isimangaliso Wetland Park and Thanda Private Game Reserve (TPGR) all of which are bordered by a matrix of natural habitats and human settlements. Thus, land outside these protected areas could be utilized to expand wild dog distribution and provide connectivity between existing resident populations of wild dogs within KwaZulu‐Natal. To investigate the viability of such an approach, Maximum Entropy Modelling (Maxent) was used to characterize habitat niche selection of dispersing wild dogs, and to identify potential dispersal linkages between current wild dog metapopulation reserves. The model was calibrated using 132 location points collected from 2006 until 2009. From 2008 to 2009 I also conducted a survey of 247 community members in tribal authorities bordering HiP and MGR, to understand factors influencing attitudes towards wild dogs. A habitat suitability model with seven predictor variables had an AUC of 0.96 (SD = 0.02) and indicated four variables which best predicted probability of presence for dispersing wild dogs: elevation, road density, land cover and human density. The results suggest that elevation and land cover may be of greater influence for dispersing wild dogs than human density or activity. Elevation was the single most effective variable indicating a higher probability of presence for dispersing wild dogs in lower lying locations; peaking at approximately 200 – 300m a.s.l. Wild dogs also showed a preference for Woodland and Bushland habitats which in KwaZulu‐Natal tend to be found on lower lying topography. A preference for areas of lower human density and a highest probability of presence at road densities of approximately 0.7km/km2 or less would suggest that while wild dogs may show a tendency to avoid areas of high human activity, they can coexist in close proximity to humans. Respondent’s attitudes, knowledge of wild dogs and livestock husbandry were interpreted by the development of a set of indices. Attitudes were positively related to formal education levels and wild dog‐specific education, but were not influenced by demographic factors such as gender, age and employment status. Eighty three percent of respondents believed efforts to protect wild dogs should continue. Respondents with higher numbers of livestock tended to have more positive attitudes towards wild dogs despite generally incurring higher losses to carnivore depredation than those with less livestock. This appears to be because the financial burden of livestock losses to those with fewer livestock is perceived to be a loss of a greater proportion of total financial wealth. The study highlighted the substantial scope for improvement in livestock management. Theft (34 percent), drought (30 percent) and disease (14 percent) were ranked as the greatest problems facing livestock owners while predators were ranked as the greatest problem by only 4 percent of respondents. My findings suggest that wild dogs are generally viewed positively or with ambivalence. Concerns over the potentially increasing threat to livestock, as natural prey numbers outside protected areas decline and wild dogs disperse from natal packs, are likely to be manageable. However, wild dog population expansion within KwaZulu‐Natal will continue to rely on managed core populations on perimeter‐fenced metapopulation reserves with tolerant communities and landowners contributing to the connectivity of isolated reserves. Generation of tolerance can be instilled through continued advocacy and education, supported by conflict mitigation initiatives and rapid response to conflict reports. The implementation of incentive schemes for adjoining private landowners to co‐manage wild dog populations will need to be addressed in conjunction with managed metapopulation practices and law enforcement, to promote range expansion, and reduce potentially lethal edge effects and wild dog‐human conflict.
- Full Text:
- Date Issued: 2012
- Authors: Whittington‐Jones, Brendan Mark
- Date: 2012
- Subjects: African wild dog , African wild dog -- Conservation -- South Africa -- KwazuluNatal , African wild dog -- Dispersal -- South Africa -- KwaZulu-Natal , African wild dog -- Effect of human beings on -- South Africa -- KwaZulu Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5893 , http://hdl.handle.net/10962/d1013414
- Description: The number of African wild dogs Lycaon pictus in Northern KwaZulu‐Natal, South Africa has increased substantially over the last six years. This is largely due to a managed metapopulation approach of introductions onto protected areas and private game reserves since 1998. Because of the increasing wild dog population, the likelihood of rural communities surrounding protected areas encountering dispersing wild dogs in northern KwaZulu‐Natal has also increased. Resident wild dog populations currently occur in Hluhluwe‐iMfolozi Park (HiP), Mkhuze Game Reserve (MGR) of Isimangaliso Wetland Park and Thanda Private Game Reserve (TPGR) all of which are bordered by a matrix of natural habitats and human settlements. Thus, land outside these protected areas could be utilized to expand wild dog distribution and provide connectivity between existing resident populations of wild dogs within KwaZulu‐Natal. To investigate the viability of such an approach, Maximum Entropy Modelling (Maxent) was used to characterize habitat niche selection of dispersing wild dogs, and to identify potential dispersal linkages between current wild dog metapopulation reserves. The model was calibrated using 132 location points collected from 2006 until 2009. From 2008 to 2009 I also conducted a survey of 247 community members in tribal authorities bordering HiP and MGR, to understand factors influencing attitudes towards wild dogs. A habitat suitability model with seven predictor variables had an AUC of 0.96 (SD = 0.02) and indicated four variables which best predicted probability of presence for dispersing wild dogs: elevation, road density, land cover and human density. The results suggest that elevation and land cover may be of greater influence for dispersing wild dogs than human density or activity. Elevation was the single most effective variable indicating a higher probability of presence for dispersing wild dogs in lower lying locations; peaking at approximately 200 – 300m a.s.l. Wild dogs also showed a preference for Woodland and Bushland habitats which in KwaZulu‐Natal tend to be found on lower lying topography. A preference for areas of lower human density and a highest probability of presence at road densities of approximately 0.7km/km2 or less would suggest that while wild dogs may show a tendency to avoid areas of high human activity, they can coexist in close proximity to humans. Respondent’s attitudes, knowledge of wild dogs and livestock husbandry were interpreted by the development of a set of indices. Attitudes were positively related to formal education levels and wild dog‐specific education, but were not influenced by demographic factors such as gender, age and employment status. Eighty three percent of respondents believed efforts to protect wild dogs should continue. Respondents with higher numbers of livestock tended to have more positive attitudes towards wild dogs despite generally incurring higher losses to carnivore depredation than those with less livestock. This appears to be because the financial burden of livestock losses to those with fewer livestock is perceived to be a loss of a greater proportion of total financial wealth. The study highlighted the substantial scope for improvement in livestock management. Theft (34 percent), drought (30 percent) and disease (14 percent) were ranked as the greatest problems facing livestock owners while predators were ranked as the greatest problem by only 4 percent of respondents. My findings suggest that wild dogs are generally viewed positively or with ambivalence. Concerns over the potentially increasing threat to livestock, as natural prey numbers outside protected areas decline and wild dogs disperse from natal packs, are likely to be manageable. However, wild dog population expansion within KwaZulu‐Natal will continue to rely on managed core populations on perimeter‐fenced metapopulation reserves with tolerant communities and landowners contributing to the connectivity of isolated reserves. Generation of tolerance can be instilled through continued advocacy and education, supported by conflict mitigation initiatives and rapid response to conflict reports. The implementation of incentive schemes for adjoining private landowners to co‐manage wild dog populations will need to be addressed in conjunction with managed metapopulation practices and law enforcement, to promote range expansion, and reduce potentially lethal edge effects and wild dog‐human conflict.
- Full Text:
- Date Issued: 2012
An investigation into tools and protocols for commercial audio web-site creation
- Authors: Ndinga, S'busiso Simon
- Date: 2000
- Subjects: Web sites -- Design , Digital libraries , Internet -- Security measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4621 , http://hdl.handle.net/10962/d1006488 , Web sites -- Design , Digital libraries , Internet -- Security measures
- Description: This thesis presents a feasibility study of a Web-based digital music library and purchasing system. It investigates the current status of the enabling technologies for developing such a system. An analysis of various Internet audio codecs, streaming audio protocols, Internet credit card payment security methods, and ways for accessing remote Web databases is presented. The objective of the analysis is to determine the viability and the economic benefits of using these technologies when developing systems that facilitate music distribution over the Internet. A prototype of a distributed digital music library and purchasing system named WAPS (for Web-based Audio Purchasing System) was developed and implemented in the Java programming language. In this thesis both the physical and the logical component elements of WAPS are explored in depth so as to provide an insight into the inherent problems of creating such a system, as well as the overriding benefits derived from the creation of such a system.
- Full Text:
- Date Issued: 2000
- Authors: Ndinga, S'busiso Simon
- Date: 2000
- Subjects: Web sites -- Design , Digital libraries , Internet -- Security measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4621 , http://hdl.handle.net/10962/d1006488 , Web sites -- Design , Digital libraries , Internet -- Security measures
- Description: This thesis presents a feasibility study of a Web-based digital music library and purchasing system. It investigates the current status of the enabling technologies for developing such a system. An analysis of various Internet audio codecs, streaming audio protocols, Internet credit card payment security methods, and ways for accessing remote Web databases is presented. The objective of the analysis is to determine the viability and the economic benefits of using these technologies when developing systems that facilitate music distribution over the Internet. A prototype of a distributed digital music library and purchasing system named WAPS (for Web-based Audio Purchasing System) was developed and implemented in the Java programming language. In this thesis both the physical and the logical component elements of WAPS are explored in depth so as to provide an insight into the inherent problems of creating such a system, as well as the overriding benefits derived from the creation of such a system.
- Full Text:
- Date Issued: 2000
The effect of environmental factors and hormone treatments on ovulation rate and spawning success in cardinal tetras, Paracheirodon axelrodi (Pisces: Characidae)
- Authors: Burton, Simon Mark
- Date: 1998
- Subjects: Characidae , Characidae -- Breeding , Tropical fish -- Breeding , Fishes -- Induced spawning , Characidae -- Spawning
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5273 , http://hdl.handle.net/10962/d1005117 , Characidae , Characidae -- Breeding , Tropical fish -- Breeding , Fishes -- Induced spawning , Characidae -- Spawning
- Description: Cardinal tetras, Paracheirodon axelrodi (Pisces: Characidae), are among the most popular tropical ornamental fish in the world. Millions of cardinal tetras are removed from their natural habitat, the upper tributaries of the Rio Negro in Brazil, each year and exported to North America and Europe where they are abundantly available at low cost. This, combined with the fact that they do not spawn freely in captivity has excluded any incentive to culture this fish on a commercial scale in these areas. However, the demand for cardinal tetras in South Africa is high, but their availability is limited to sporadic imports of wild caught fish which has resulted in an increase in their relative value. Thus, there is an appreciable incentive to investigate methods for inducing this species to reproduce in captivity. Information on methods for inducing spawning would form an integral part of a potential production plan for the culture of this species in South Africa. This study consisted of a number of experiments designed to investigate factors related to the spawning of cardinal tetras in captivity. The first series of experiments investigated the effect of variables such as the water chemistry of the experimental system, the sex ratio of the fish, the effect of conditioning and the effect of different spawning media on spawning success. The second series of experiments tested the effects of various environmental stimuli or hormonal treatments on spawning in cardinal tetras. Environmental stimuli tested included a rise in temperature, a rise in water level and a fresh rain water flush. Hormonal treatments included feeding GnRHa enriched brine shrimps to the fish or the application of hormone injections (hypophysation). Neither environmental stimuli nor brine shrimp enrichment induced cardinals to spawn in a repeatable manner. The same was true for hypophysation, but in this case a low incedence of ovulation of injected females was observed. Oocytes from ovulated and non-ovulated females were examined under a microscope and from this it was determined that cardinal tetras are group synchronous spawners, containing two distinct cohorts of oocytes in the ovary. The effect of a number of environmental stimuli on ovulation rate in cardinal tetras were then tested but did not induce ovulation in any females. A series of three experiments was performed investigating the effect of conditioning the sexes together on ovulation rate and spawning success. Conditioning the sexes together had no effect on spawning success, but a significantly higher ovulation rate was observed in females that vvere conditioned together with males. Male cardinals did not follow this trend and lost condition when conditioned together with females. The next experiment tested if pheromones from red serpae tetras, Hyphessobrycon serpae, could be used to induce ovulation and spawning in cardinal tetras. This was found not to be the case. The final series of experiments tested the effect of Aquaspawn® enriched Artemia on ovulation rates in female cardinal tetras. Aquaspawn® is a water soluble preparation of GnRHa and dopamine. Aquaspawn® enriched Artemia were found to be effective for inducing female cardinal tetras to ovulate. However, the results from this method of enrichment were not entirely reliable and further research is warranted. Finally, a protocol for evaluating spawning in topical, freshwater egg-laying fish was proposed, based on the results from this study. The advantages and disadvantages of such a protocol were discussed.
- Full Text:
- Date Issued: 1998
- Authors: Burton, Simon Mark
- Date: 1998
- Subjects: Characidae , Characidae -- Breeding , Tropical fish -- Breeding , Fishes -- Induced spawning , Characidae -- Spawning
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5273 , http://hdl.handle.net/10962/d1005117 , Characidae , Characidae -- Breeding , Tropical fish -- Breeding , Fishes -- Induced spawning , Characidae -- Spawning
- Description: Cardinal tetras, Paracheirodon axelrodi (Pisces: Characidae), are among the most popular tropical ornamental fish in the world. Millions of cardinal tetras are removed from their natural habitat, the upper tributaries of the Rio Negro in Brazil, each year and exported to North America and Europe where they are abundantly available at low cost. This, combined with the fact that they do not spawn freely in captivity has excluded any incentive to culture this fish on a commercial scale in these areas. However, the demand for cardinal tetras in South Africa is high, but their availability is limited to sporadic imports of wild caught fish which has resulted in an increase in their relative value. Thus, there is an appreciable incentive to investigate methods for inducing this species to reproduce in captivity. Information on methods for inducing spawning would form an integral part of a potential production plan for the culture of this species in South Africa. This study consisted of a number of experiments designed to investigate factors related to the spawning of cardinal tetras in captivity. The first series of experiments investigated the effect of variables such as the water chemistry of the experimental system, the sex ratio of the fish, the effect of conditioning and the effect of different spawning media on spawning success. The second series of experiments tested the effects of various environmental stimuli or hormonal treatments on spawning in cardinal tetras. Environmental stimuli tested included a rise in temperature, a rise in water level and a fresh rain water flush. Hormonal treatments included feeding GnRHa enriched brine shrimps to the fish or the application of hormone injections (hypophysation). Neither environmental stimuli nor brine shrimp enrichment induced cardinals to spawn in a repeatable manner. The same was true for hypophysation, but in this case a low incedence of ovulation of injected females was observed. Oocytes from ovulated and non-ovulated females were examined under a microscope and from this it was determined that cardinal tetras are group synchronous spawners, containing two distinct cohorts of oocytes in the ovary. The effect of a number of environmental stimuli on ovulation rate in cardinal tetras were then tested but did not induce ovulation in any females. A series of three experiments was performed investigating the effect of conditioning the sexes together on ovulation rate and spawning success. Conditioning the sexes together had no effect on spawning success, but a significantly higher ovulation rate was observed in females that vvere conditioned together with males. Male cardinals did not follow this trend and lost condition when conditioned together with females. The next experiment tested if pheromones from red serpae tetras, Hyphessobrycon serpae, could be used to induce ovulation and spawning in cardinal tetras. This was found not to be the case. The final series of experiments tested the effect of Aquaspawn® enriched Artemia on ovulation rates in female cardinal tetras. Aquaspawn® is a water soluble preparation of GnRHa and dopamine. Aquaspawn® enriched Artemia were found to be effective for inducing female cardinal tetras to ovulate. However, the results from this method of enrichment were not entirely reliable and further research is warranted. Finally, a protocol for evaluating spawning in topical, freshwater egg-laying fish was proposed, based on the results from this study. The advantages and disadvantages of such a protocol were discussed.
- Full Text:
- Date Issued: 1998
Women's experience of abortion : a qualitative study
- Authors: Taylor, Gaye Lesley
- Date: 1998
- Subjects: Abortion , Abortion -- South Africa , Women -- Counseling of
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:708 , http://hdl.handle.net/10962/d1006522 , Abortion , Abortion -- South Africa , Women -- Counseling of
- Description: Abortion is an emotive topic that always raises strong feelings. The purpose of this study, however, is not to focus on the religious, political or moral questions surrounding abortion. Abortion is a reality and in South Africa, where it has only recently become legal, there is a need to have an understanding of the effects on women in order to provide counselling services. There is also a need to provide services for the many women who have had illegal terminations in the past. This study reviewed the most recent literature on the subject and the researcher takes the view that although the scientific literature states there is little long term psychological effect of abortion, the non-positivist literature which records women's experiences tells another story. Some of the problems with the scientific literature is that psychological effects are not defined and there may be political motivation for the study, ie. an attempt is made to prove that the health costs are not high for abortion because there is little long term effect. The researcher, however, feels this does a disservice to women who have had abortions because there is a failure to provide counselling services. Some members of the feminist movement also deserve criticism because in their haste to give women their rights they fail to allow a woman to thoroughly explore her options beforehand and to provide support services afterwards. The researcher, however, also identified a new theme in the literature which has been called a maturing of the feminist viewpoint that along with the right to abortion, women also have a right to the mixed feelings that go with making, what is for many, a very painful decision. There is a recognition that abortion is about loss and thus there is a corresponding need to acknowledge women's need to mourn and to provide services. The study does not include the experience of women who seek abortions for reasons of poverty. It also excludes the experience of women who have abortions as a result of rape, incest or harm to the foetus. It is a qualitative study and a non-probability sampling technique which comprised snowball and purposive methods was used to identify respondents. In-depth semi-structured interviews using a broad theme of questions were conducted with five respondents. The women were asked to tell the stories of their abortions: their and their partner's feelings before and after, how they decided and the actual experience. They were also asked to identify counselling requirements, what they found helpful and what would have helped. The literature and the findings support the researcher's view that women who find themselves with an unexpected pregnancy need an opportunity to objectively consider all their options, namely keeping the baby, adoption or abortion, and to have an objective counsellor assist them in vigorously considering these. If they decide on a termination they need to be given as much information as possible about the procedure and about how they are likely to feel. Afterwards counselling should be made available and women should be encouraged to use the service. They need to be assisted to explore all ways of coming to terms with it such as through dream work, dialogueing with the unborn child through a letter and for those with religious beliefs seeking absolution from the church. There is a great need for a Christian and other religious ministry in this regard. Self-help therapies such as support groups can also be helpful
- Full Text:
- Date Issued: 1998
- Authors: Taylor, Gaye Lesley
- Date: 1998
- Subjects: Abortion , Abortion -- South Africa , Women -- Counseling of
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:708 , http://hdl.handle.net/10962/d1006522 , Abortion , Abortion -- South Africa , Women -- Counseling of
- Description: Abortion is an emotive topic that always raises strong feelings. The purpose of this study, however, is not to focus on the religious, political or moral questions surrounding abortion. Abortion is a reality and in South Africa, where it has only recently become legal, there is a need to have an understanding of the effects on women in order to provide counselling services. There is also a need to provide services for the many women who have had illegal terminations in the past. This study reviewed the most recent literature on the subject and the researcher takes the view that although the scientific literature states there is little long term psychological effect of abortion, the non-positivist literature which records women's experiences tells another story. Some of the problems with the scientific literature is that psychological effects are not defined and there may be political motivation for the study, ie. an attempt is made to prove that the health costs are not high for abortion because there is little long term effect. The researcher, however, feels this does a disservice to women who have had abortions because there is a failure to provide counselling services. Some members of the feminist movement also deserve criticism because in their haste to give women their rights they fail to allow a woman to thoroughly explore her options beforehand and to provide support services afterwards. The researcher, however, also identified a new theme in the literature which has been called a maturing of the feminist viewpoint that along with the right to abortion, women also have a right to the mixed feelings that go with making, what is for many, a very painful decision. There is a recognition that abortion is about loss and thus there is a corresponding need to acknowledge women's need to mourn and to provide services. The study does not include the experience of women who seek abortions for reasons of poverty. It also excludes the experience of women who have abortions as a result of rape, incest or harm to the foetus. It is a qualitative study and a non-probability sampling technique which comprised snowball and purposive methods was used to identify respondents. In-depth semi-structured interviews using a broad theme of questions were conducted with five respondents. The women were asked to tell the stories of their abortions: their and their partner's feelings before and after, how they decided and the actual experience. They were also asked to identify counselling requirements, what they found helpful and what would have helped. The literature and the findings support the researcher's view that women who find themselves with an unexpected pregnancy need an opportunity to objectively consider all their options, namely keeping the baby, adoption or abortion, and to have an objective counsellor assist them in vigorously considering these. If they decide on a termination they need to be given as much information as possible about the procedure and about how they are likely to feel. Afterwards counselling should be made available and women should be encouraged to use the service. They need to be assisted to explore all ways of coming to terms with it such as through dream work, dialogueing with the unborn child through a letter and for those with religious beliefs seeking absolution from the church. There is a great need for a Christian and other religious ministry in this regard. Self-help therapies such as support groups can also be helpful
- Full Text:
- Date Issued: 1998
Design automation of a machine-independent code generator
- Authors: Clayton, Peter Graham
- Date: 1984 , 2013-01-22
- Subjects: Compilers (Computer programs) , Programming languages (Electronic computers)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4676 , http://hdl.handle.net/10962/d1006699 , Compilers (Computer programs) , Programming languages (Electronic computers)
- Description: As both computer languages and architectures continue to proliferate, there is a continuing need for new compilers. Researchers have attempted to ease the work of producing compilers by developing methods to automate compiler writing. While much work has been done (and considerable success achieved) in writing parsers which can handle a variety of source languages (using mainly table-driven analysis methods), less progress has been made in formalizing the code generation end of the compiler. Nevertheless, some of the more recent publications in code generation stress portability or retargetability of the resulting compiler. A number of code generator synthesisers have been developed, some of which produce code that can be compared in quality with that produced by a conventional code generator. However, because of the complexity of generalizing the mapping from source language to target machine, and the need for efficiency of various kinds, code generator synthesisers are large, complicated programs. Consequently, the person who develops a code generator using one of these tools invariably needs to be a code generation specialist himself. Many compilers follow a pattern of having a front end which generates intermediate code, and a back end which converts intermediate code to machine code. The intermediate code is effectively machine independent, or can be designed that way. With these points in mind, we have set out to write a system of programs which -- 1. will allow the generation of such a back end in a reasonably short time, for a general intermediate code, and for a general machine code, and -- 2. can be used by anyone who has a sound knowledge of the target machine's architecture and associated assembler language, but is not necessarily a specialist compiler writer. The system consists of a series of friendly, interactive programs by means of which the user sets up tables defining the architecture and assembly level instructions for the target machine, and the code templates onto which intermediate codes produced by a parser have been mapped. A general notation has been developed to represent machine instructions using the same format as the target assembler. Thus the code generator writer is able to write code sequences to perform the effects of the intermediate codes, using assembly mnemonics familiar to him. The resultant table-driven code generator simply replaces a sequence of intermediate codes by their respective code templates, relocating them in memory and filling in addresses known only at code-generation time. This thesis describes the use and implementation details of this generalized code generation system. As an example, the implementation of a code generator for a CLANG [23] parser on an 8080 processor is described. The discussion also includes guide-lines on how to implement a loader and associated run-time routines for use in executing the object code. The results of a number of bench-marks have shown, as expected, that code produced by a code generator developed in this manner is larger and slower than that from a special purpose optimizing code generator, but is still several times faster than interpreting the intermediate code. The major benefit to be gained from using this system lies in the shorter development time by a less skilled person. , KMBT_223 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 1984
- Authors: Clayton, Peter Graham
- Date: 1984 , 2013-01-22
- Subjects: Compilers (Computer programs) , Programming languages (Electronic computers)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4676 , http://hdl.handle.net/10962/d1006699 , Compilers (Computer programs) , Programming languages (Electronic computers)
- Description: As both computer languages and architectures continue to proliferate, there is a continuing need for new compilers. Researchers have attempted to ease the work of producing compilers by developing methods to automate compiler writing. While much work has been done (and considerable success achieved) in writing parsers which can handle a variety of source languages (using mainly table-driven analysis methods), less progress has been made in formalizing the code generation end of the compiler. Nevertheless, some of the more recent publications in code generation stress portability or retargetability of the resulting compiler. A number of code generator synthesisers have been developed, some of which produce code that can be compared in quality with that produced by a conventional code generator. However, because of the complexity of generalizing the mapping from source language to target machine, and the need for efficiency of various kinds, code generator synthesisers are large, complicated programs. Consequently, the person who develops a code generator using one of these tools invariably needs to be a code generation specialist himself. Many compilers follow a pattern of having a front end which generates intermediate code, and a back end which converts intermediate code to machine code. The intermediate code is effectively machine independent, or can be designed that way. With these points in mind, we have set out to write a system of programs which -- 1. will allow the generation of such a back end in a reasonably short time, for a general intermediate code, and for a general machine code, and -- 2. can be used by anyone who has a sound knowledge of the target machine's architecture and associated assembler language, but is not necessarily a specialist compiler writer. The system consists of a series of friendly, interactive programs by means of which the user sets up tables defining the architecture and assembly level instructions for the target machine, and the code templates onto which intermediate codes produced by a parser have been mapped. A general notation has been developed to represent machine instructions using the same format as the target assembler. Thus the code generator writer is able to write code sequences to perform the effects of the intermediate codes, using assembly mnemonics familiar to him. The resultant table-driven code generator simply replaces a sequence of intermediate codes by their respective code templates, relocating them in memory and filling in addresses known only at code-generation time. This thesis describes the use and implementation details of this generalized code generation system. As an example, the implementation of a code generator for a CLANG [23] parser on an 8080 processor is described. The discussion also includes guide-lines on how to implement a loader and associated run-time routines for use in executing the object code. The results of a number of bench-marks have shown, as expected, that code produced by a code generator developed in this manner is larger and slower than that from a special purpose optimizing code generator, but is still several times faster than interpreting the intermediate code. The major benefit to be gained from using this system lies in the shorter development time by a less skilled person. , KMBT_223 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 1984
The geochemistry and petrology of Karroo basalts of the Barkly East area, north eastern Cape
- Authors: Pemberton, John
- Date: 1978 , 2013-10-17
- Subjects: Basalt -- South Africa -- Eastern Cape , Petrology -- South Africa -- Eastern Cape , Geochemistry -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5042 , http://hdl.handle.net/10962/d1007646 , Basalt -- South Africa -- Eastern Cape , Petrology -- South Africa -- Eastern Cape , Geochemistry -- South Africa -- Eastern Cape
- Description: Sixty one basalt samples from the Drakensberg Subgroup in the Barkly East area were analysed for major elements and fourteen trace elements viz. Sr, Rb, Zr, Y, Nb, Zn, Cu, Ni, Co, V, Cr, La, Ce and Nd . These data confirm the tholeiitic nature of the Drakensberg Subgroup. Geochemical differences in the major element compositions are small within the different units of the Drakensberg Subgroup. Small differences are also evident between these units. The trace element variation between the units and within the Lesotho Formation are more pronounced than the variation of the major elements. The Lesotho Formation samples show a minor vertical increase in value for the top half of the Naudes Nek section in Fe, Ti, P, Zr, Nb, Y, La, Ce and Nd . A decrease in value from the same position in Mg, Ni and Co was observed. These patterns of variation are interpreted as representing low-pressure fractionation of plagioclase, olivine and clinopyroxene. Differences between the units of the Drakensberg Subgroup are examined by using absolute trace element contents and interelement ratios. Ratios of incompatible elements differ for the different units leading to the suggestion that a heterogeneous mantle is the most likely explanation for these differences. A unique unit of flows designated the Omega Formation is examined. The basal massive unit displays an unusual pattern of variation with height which suggests an origin through two different differentiation mechanisms. The data from this thesis are compared with those of Cox and Hornung (1966) on the central Lesotho basalts, Bristow (1976) on the southern Lebombo basalts and Robey (1976) on the Karroo dolerites of the Eastern Cape. The geochemical comparison between the lavas of the Lesotho Formation in the Barkly East area, central Lesotho and the Karroo dolerites show no major differences. However the southern Lebombo basalts show an enrichment in Sr and depletion in Cr.
- Full Text:
- Date Issued: 1978
- Authors: Pemberton, John
- Date: 1978 , 2013-10-17
- Subjects: Basalt -- South Africa -- Eastern Cape , Petrology -- South Africa -- Eastern Cape , Geochemistry -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5042 , http://hdl.handle.net/10962/d1007646 , Basalt -- South Africa -- Eastern Cape , Petrology -- South Africa -- Eastern Cape , Geochemistry -- South Africa -- Eastern Cape
- Description: Sixty one basalt samples from the Drakensberg Subgroup in the Barkly East area were analysed for major elements and fourteen trace elements viz. Sr, Rb, Zr, Y, Nb, Zn, Cu, Ni, Co, V, Cr, La, Ce and Nd . These data confirm the tholeiitic nature of the Drakensberg Subgroup. Geochemical differences in the major element compositions are small within the different units of the Drakensberg Subgroup. Small differences are also evident between these units. The trace element variation between the units and within the Lesotho Formation are more pronounced than the variation of the major elements. The Lesotho Formation samples show a minor vertical increase in value for the top half of the Naudes Nek section in Fe, Ti, P, Zr, Nb, Y, La, Ce and Nd . A decrease in value from the same position in Mg, Ni and Co was observed. These patterns of variation are interpreted as representing low-pressure fractionation of plagioclase, olivine and clinopyroxene. Differences between the units of the Drakensberg Subgroup are examined by using absolute trace element contents and interelement ratios. Ratios of incompatible elements differ for the different units leading to the suggestion that a heterogeneous mantle is the most likely explanation for these differences. A unique unit of flows designated the Omega Formation is examined. The basal massive unit displays an unusual pattern of variation with height which suggests an origin through two different differentiation mechanisms. The data from this thesis are compared with those of Cox and Hornung (1966) on the central Lesotho basalts, Bristow (1976) on the southern Lebombo basalts and Robey (1976) on the Karroo dolerites of the Eastern Cape. The geochemical comparison between the lavas of the Lesotho Formation in the Barkly East area, central Lesotho and the Karroo dolerites show no major differences. However the southern Lebombo basalts show an enrichment in Sr and depletion in Cr.
- Full Text:
- Date Issued: 1978
Some aspects of the animal ecology of Rhenosterbos: Elytropappus rhinocerotis (L.f.) Less
- Authors: Shiff, Clive Julian
- Date: 1957
- Subjects: Animal ecology -- South Africa , Rhenosterbos
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5880 , http://hdl.handle.net/10962/d1013200
- Description: Rhenosterbos, Elytropappus rhinocerotis (L.f.) Less belongs to a purely South African section ot the Compositae. It is restricted to an area of low rainfall which is evenly distributed over the year. The plant is a specialised xerophyte with minute leaves and white pubescent twiglets. Older stems become woody and dry and bear no leaves. The shrubs have a life span of about eight years; the plants are most succulent and luxurious during the third and fourth year, after which they tend to become woody and scraggly. For this investigation insect material was obtained by sweep-net collection and field observation. In the Grahamatown district 78 collections were made during the period March - November 1953, with data thus obtained being embodied in this work. In addition to this, collections were made in the Cradock-Hofmeyer, Uitenhage, Riversdale, Bot River, Swellendam and Stellenbosch districts. Twenty species of insects have been shown definitely to feed on the plant and there are another 13 which probably feed on it. Of the 20 species attached to the plant, 12 are sucking forms belonging to the Orders Homoptera and Hemipters. They include six Coccids, two Jassids a Cercopid, two Mirids and a Pentstomid. The Coleoptera are represented by one or perhaps two species which feed on the plant. The Lepidoptera are represented by two important species of moth, a Geometrid and a Pyralid. Four species of gall forming Diptera are associated with the plant. There are two species of Trypetidae which are responsible for piriform swellings of growth points and are distributed evenly throughout the bush. There are also two Cecidomyidae one of which develops in the growth points of the shoots and is responsible tor a minute tubular gall. The other develops in a fusiform stem gall. This latter gall has been shown to be more common on smaller bushes than on larger ones, implying that the adult female may show certain selective powers during oviposition. The size of the insect population is held in check by spiders mantids and other general predators. There are several Coccinellids which prey on the scale insects. Rhenosterbos supports a small, well regulated community of insects. The balance between plant and animal is very dellcate because of the high degree of specialisation of the plant. On occasions this balance has been known to break down, and the insects present in abundance have swamped and killed large patches of the plant.
- Full Text:
- Date Issued: 1957
- Authors: Shiff, Clive Julian
- Date: 1957
- Subjects: Animal ecology -- South Africa , Rhenosterbos
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5880 , http://hdl.handle.net/10962/d1013200
- Description: Rhenosterbos, Elytropappus rhinocerotis (L.f.) Less belongs to a purely South African section ot the Compositae. It is restricted to an area of low rainfall which is evenly distributed over the year. The plant is a specialised xerophyte with minute leaves and white pubescent twiglets. Older stems become woody and dry and bear no leaves. The shrubs have a life span of about eight years; the plants are most succulent and luxurious during the third and fourth year, after which they tend to become woody and scraggly. For this investigation insect material was obtained by sweep-net collection and field observation. In the Grahamatown district 78 collections were made during the period March - November 1953, with data thus obtained being embodied in this work. In addition to this, collections were made in the Cradock-Hofmeyer, Uitenhage, Riversdale, Bot River, Swellendam and Stellenbosch districts. Twenty species of insects have been shown definitely to feed on the plant and there are another 13 which probably feed on it. Of the 20 species attached to the plant, 12 are sucking forms belonging to the Orders Homoptera and Hemipters. They include six Coccids, two Jassids a Cercopid, two Mirids and a Pentstomid. The Coleoptera are represented by one or perhaps two species which feed on the plant. The Lepidoptera are represented by two important species of moth, a Geometrid and a Pyralid. Four species of gall forming Diptera are associated with the plant. There are two species of Trypetidae which are responsible for piriform swellings of growth points and are distributed evenly throughout the bush. There are also two Cecidomyidae one of which develops in the growth points of the shoots and is responsible tor a minute tubular gall. The other develops in a fusiform stem gall. This latter gall has been shown to be more common on smaller bushes than on larger ones, implying that the adult female may show certain selective powers during oviposition. The size of the insect population is held in check by spiders mantids and other general predators. There are several Coccinellids which prey on the scale insects. Rhenosterbos supports a small, well regulated community of insects. The balance between plant and animal is very dellcate because of the high degree of specialisation of the plant. On occasions this balance has been known to break down, and the insects present in abundance have swamped and killed large patches of the plant.
- Full Text:
- Date Issued: 1957
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