The effect of phytocannabinoid treatment on adipogenesis and lipolysis in 3T3-L1 cells
- Authors: Ramlugon, Sonaal
- Date: 2014
- Subjects: Cannabinoids , Adipose tissues , Cannabis -- Therapeutic use
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10361 , http://hdl.handle.net/10948/d1021072
- Description: During the 1800’s cannabis use was described as a treatment for a variety of metabolic disorders but its recreational use in the twentieth century resulted in laws which made the usage of cannabis illegal despite its medicinal properties. Cannabis usage has been reported to be useful in the treatment of Type 2 diabetes but unfortunately conflicting results are often published and its mechanism of action is still unknown. The aim of this project was to investigate the effect of phytocannabinoid treatment on adipogenesis and lipolysis in 3T3-L1 cells, to unravel their mechanism of action and also to test for potential anti-diabetic properties. The studies showed that phytocannabinoid treatment promoted higher glucose uptake and significantly less fat accumulation when compared to Rosiglitazone. Rosiglitazone is an anti-diabetic drug that has recently been withdrawn from the market since its usage has been associated with severe side effects. It was also found that during the 1800’s cannabis use was described as a treatment for a variety of metabolic disorders but its recreational use in the twentieth century resulted in laws which made the usage of cannabis illegal despite its medicinal properties. Cannabis usage has been reported to be useful in the treatment of Type 2 diabetes but unfortunately conflicting results are often published and its mechanism of action is still unknown. The aim of this project was to investigate the effect of phytocannabinoid treatment on adipogenesis and lipolysis in 3T3-L1 cells, to unravel their mechanism of action and also to test for potential anti-diabetic properties. The studies showed that phytocannabinoid treatment promoted higher glucose uptake and significantly less fat accumulation when compared to Rosiglitazone. Rosiglitazone is an anti-diabetic drug that has recently been withdrawn from the market since its usage has been associated with severe side effects. It was also found that phytocannabinoid treatment was able to reverse the insulin-resistant state of 3T3-L1 cells. The study indicates that the mechanism of action occurs at the mitochondrial level where enzymes such as succinate dehydrogenase and glycerol-3-phosphate dehydrogenase are modulated thereby affecting oxidative phosphorylation involved in the respiratory chain. In addition the effect observed with phytocannabinoid treatment is time dependent and affects the cells differently at different developmental stages. Therefore it can be concluded that phytocannabinoid treatment not only helps to maintain the balance between adipogenesis and lipolysis in 3T3-L1 cells but its use may also be helpful in the treatment of Type 2 diabetes and/or obesity-related insulin resistance.phytocannabinoid treatment was able to reverse the insulin-resistant state of 3T3-L1 cells. The study indicates that the mechanism of action occurs at the mitochondrial level where enzymes such as succinate dehydrogenase and glycerol-3-phosphate dehydrogenase are modulated thereby affecting oxidative phosphorylation involved in the respiratory chain. In addition the effect observed with phytocannabinoid treatment is time dependent and affects the cells differently at different developmental stages. Therefore it can be concluded that phytocannabinoid treatment not only helps to maintain the balance between adipogenesis and lipolysis in 3T3-L1 cells but its use may also be helpful in the treatment of Type 2 diabetes and/or obesity-related insulin resistance.
- Full Text:
- Date Issued: 2014
The effects of the labour skills shortage in the construction industry
- Authors: Vanqa, Inga Bongo
- Date: 2014
- Subjects: Construction industry -- South Africa , Building trades -- Employees , Skilled labor -- South Africa , Labor supply -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9728 , http://hdl.handle.net/10948/d1021125
- Description: Purpose of this treatise: The aim of this research is to determine, if the skilled labour shortage has had any impact on how construction projects are executed. If there is an impact the study aims to determine the nature and extent of the problem. Design/methodology/approach: A review of related literature was conducted, mainly to ensure that existing research is not replicated, in order to generate new ideas. The quantitative research approach was applied for this research. The questionnaire was designed so that scores can be easily summed in order to obtain an overall measure of the attitudes and opinions of the respondents. Findings: The results revealed that the skilled labour shortage has a negative effect on how construction projects are executed. The results further revealed that the biggest concern amongst employers and management of construction companies was the negative impact the shortage of skilled labour has on the levels of workmanship. Research limitations: The sample (construction companies) is mostly situated in the Gauteng province of South Africa. Practical implications: The research is of importance to managers and supervisors of construction companies of all sizes. The findings of this study will assist in ensuring that projects are efficiently managed irrespective of the current skills crisis in the construction industry.
- Full Text:
- Date Issued: 2014
The endocannabinoid system in inflammatory bowel system
- Authors: Ababio, Frank James Kweku
- Date: 2014
- Subjects: Inflammatory bowel diseases , Gastrointestinal system , Gastrointestinal system -- Diseases
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10346 , http://hdl.handle.net/10948/d1020338
- Description: Crohn’s disease (CD) and ulcerative colitis (UC) constitute the two major forms of inflammatory bowel disease (IBD), which are disorders of chronic inflammation in the gastrointestinal tract that are associated with significant morbidity and socioeconomic burden. IBD patients with long-standing intestinal inflammation are more prone to developing colorectal cancer (CRC). Until now, none of the existing IBD treatments is able to heal the mucosal ulcerations satisfactorily. The endocannabinoid system (ECS), which comprises of endogenous cannabinoid ligands, their receptors, and metabolic enzymes, has been implicated in gut homeostasis, visceral sensation, inflammation and gastrointestinal motility. Available studies in rodent models of IBD suggest that enhancing the ECS tone may reduce inflammation and improve mucosal integrity. This evidence indicates that the components of the ECS seem well positioned to exert a protective role in IBD and also to offer a great opportunity for therapeutic exploitation. Despite the role of the ECS in the gut, the presence and function of the components of the ECS is not well characterised in human IBD. The primary aim of the study was to investigate the state of the major components of the ECS in human IBD and to establish whether IBD is associated with any changes of the components of the ECS. Cannabinoid CB1 and CB2 receptors, enzymes for endocannabinoid biosynthesis PLC, “LRAT”, NAPE-PLD and DAGL, and endocannabinoid metabolic enzymes FAAH and MAGL were analysed from colonic tissue samples of CD, UC and control patients by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) to determine the relative mRNA expression of the above genes. The RT-qPCR analysis showed that the mRNA expression of PLC, LRAT, and NAPE-PLD were unchanged in both CD and UC, whiles DAGL mRNA was decreased in UC but was unchanged in CD. The endocannabinoid degradation enzymes, FAAH mRNA expression was also unchanged in CD but decreased in UC, whereas the mRNA expression of MAGL was significantly decreased in both CD and UC. NAPE-PLD/FAAH and DAGL/MAGL ratios, an estimation of the balance of AEA and 2-AG levels, showed that AEA and 2-AG levels could be increased and unchanged, respectively, in IBD. The mRNA expression of CB1 was significantly decreased in CD and UC whilst CB2 mRNA expression was unchanged in both forms of IBD. The study demonstrated that the components of the ECS which were investigated were present in colonic tissues of both IBD patients and healthy individuals, but they appear to be off balance in CD and UC patients. The decreased CB1 receptors in IBD patients could be an important modifier in the disease and could also provide a possible pathoaetiological mechanism linking IBD and CRC. Although these findings look promising, more studies with larger sample size are required to characterise the components of the ECS in human IBD.
- Full Text:
- Date Issued: 2014
The impacts of harvesting circumcision amaryllids from the Eastern Cape Province, South Africa
- Authors: Nombewu, Nomatile
- Date: 2014
- Subjects: Medicinal plants -- Harvesting -- South Africa -- Eastern Cape , Botany, Medical -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10640 , http://hdl.handle.net/10948/d1020648
- Description: This quantitative study seeks to determine the impacts of harvesting three plant species traditionally used for wound healing during circumcision. Three localities where these plant species occur have been identified. The population size for each species was determined and an assessment of the extent of harvesting was determined through repeated assessment of marked plants. A significant harvest of these species resulted in the unsustainable use of our natural resources. Out of 25 Boophone disticha plants marked, only one plant was remaining after two circumcision seasons. The Brunsvigia grandiflora and Scadoxus multiflorus populations monitored disappeared completely, with no single marked plant found after two circumcision seasons. Growth rates of wild populations of Boophone disticha and cultivated Brunsvigia grandiflora and Scadoxus multiflorus plants were determined. The seedling bulbs of Brunsvigia grandiflora grew significantly more slowly at less than 0.6 cm per year, while Scadoxus multiflorus grew faster at over 1 cm per year. A model for population dynamics of the three plant species was designed which showed that the plants are being harvested before they even flower. It is therefore recommended in this study that a conservation plan for these plant species must be done to save the little that is left in the wild before they become critically endangered.
- Full Text:
- Date Issued: 2014
The role of sense-of-place in climate-change adaptation: the case of Soweto-on Sea and Veeplaas
- Authors: Lupindo, Yamkela
- Date: 2014
- Subjects: Climatic changes -- South Africa -- Port Elizabeth , Human geography -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3318 , vital:20423
- Description: The study has investigated the relationship between climate-change adaptation and the role of sense-of-place on people’s decisions regarding relocation, using Soweto-On-Sea and Veeplaas as case studies. The adoption of social science methods in the investigation led to the development of indicators, which themselves were derived from theories, which explained the building blocks of sense-of-place. These indicators: place attachment, place identity and place dependence, helped explain the connection people have with home, and how these connections are influenced and affected by interactions that take place in Soweto-on-Sea and Veeplaas. The fixed-mixed methodology, along with purposive-quota sampling, provided the means of investigating climate-change adaptation and sense-of-place in Soweto-on-Sea and Veeplaas. The three indicators were used in conjunction with a six-point ranking system, which was used to analyse the findings. The ranking system measured the degree of connection people have with home. A noticeable pattern between length-of-stay, and a very strong connection, could be recognised. A gradual increase in the degree of connection to home was recognised; as younger members of the two communities scored more moderately; and the oldest members (willing to sacrifice for a place, ranking five) scored highly. A strong interplay between the indicators could be observed; and thus, a single indicator on its own could not properly explain sense-of-place; but interactions between the two theories allowed for greater understanding. The youngest members of the two communities scored lower; because their connection was based on practical issues, access to schools, police stations, cheaper public transport and a sense-of-safety; as the members in the communities knew one another. Those residents who scored high on the ranking system had a much stronger bond, which went beyond practicality; as various interactions contributed to their sense-of-place. Sense-of-place contributes significantly to people’s decisions regarding relocation; and thus, fundamental benefits in incorporating a study of sense-of-place in climate-change adaptation would allow for greater understanding, and lead to improved ways of protecting people in areas at risk.
- Full Text:
- Date Issued: 2014
Time-activity budgets of cape gannets (Morus Capensis) at Bird Island, Algoa Bay
- Authors: Rishworth, Gavin Midgley
- Date: 2014
- Subjects: Birds of prey -- Behavior -- South Africa -- Algoa Bay , Gannets -- South Africa -- Algoa Bay , Birds -- Breeding -- South Africa -- Algoa Bay
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10728 , http://hdl.handle.net/10948/d1021046
- Description: For several decades now, seabirds have been considered to be useful indicators of the state of their prey resources because of how they reflect lower-level trophic variability through proxies such as diet or behaviour. However, collection of appropriate data is often challenging in the marine environment because of logistical or financial constraints. In this study, time-activity budgets were studied in the Cape gannet (Morus capensis), a seabird which has been advocated as a potential bioindicator for local epipelagic prey. VHF transmitters attached to PVC leg-rings were fitted to 50 adult breeding pairs during the 2011/2012 and 2012/2013 breeding seasons at Bird Island, Algoa Bay, to determine whether an automated method of continuously collecting time-activity budget data can replace conventional laborious direct observations. To validate that the foraging trip duration data generated from the automated method was a reflection of foraging effort, Time-Depth Recorders (TDRs) were simultaneously equipped to birds with VHF transmitters for three weeks. In order to assess the influence of factors other than prey availability on parent time-activity budgets, sex, chick age and body condition were measured. Additionally, chick growth and survival were recorded in order to investigate the gender-specific effects of parental time-activity budget variability on these parameters. Attachment of VHF transmitters to leg-rings of adult Cape gannets had no observable negative effects on the adults or their chicks in terms of adult body condition, nest attendance and foraging trip durations, or chick growth and survival. Furthermore, the frequency distribution of behaviour bout (foraging trip and nest attendance) durations was no different between automated and directly observed data. However, the automated method did record shorter behaviour bouts, largely attributed to the increased likelihood of direct observations missing birds returning briefly to their nests during older chick provisioning. Additionally, foraging trip duration was highly correlated to foraging effort in terms of time spent resting on the sea surface, flying and diving. The automated method therefore appears to be a good reflection of direct nest attendance observations and foraging effort. Cape gannet time-activity budgets were related to chick age and parental sex. Especially as chicks neared fledging, females spent significantly longer periods of time foraging than males, with males consequently provisioning their chicks more often. Furthermore, adults departing their nests earlier spent more time away from the nest foraging as more same-day daylight hours were available. Chick growth was a function of parent foraging trip duration and associated prey delivery rates. Chick survival was most strongly affected by the amount of time which chicks were left unattended by both parents and consequently exposed to predation by kelp gulls (Larus dominicanus) or to adverse weather conditions. Additionally, for females (but not males) there appeared to be a trade-off between foraging trip duration and chick survival. The Cape gannet appears to demonstrate a strategy whereby the costs of reproduction to the female are shifted towards male-dominated chick provisioning as the chick nears fledging. Drivers of time-activity budget variability such as chick age and parental sex therefore need to be considered if using data on foraging trip duration as a proxy of foraging effort and prey availability.
- Full Text:
- Date Issued: 2014
Using a mobile pill reminder to support medication compliance in South Africa
- Authors: Mukandatsama, Cainos
- Date: 2014
- Subjects: Mobile apps -- South Africa , Mobile computing -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/4889 , vital:20719
- Description: This project investigated how to develop a mobile intervention to support medication compliance for patients with chronic and acute diseases. Chronic diseases cannot be cured but can be controlled, usually by taking medication every-day. Therefore, it is very crucial for a patient with a chronic disease to take their medication on time to prevent complications or negative impact on their health. Due to the widespread use of mobile phones, having an automated mobile mechanism to remind patients to take medication is regarded as an effective way of supporting medication compliance. The focus of the research was on investigating how mobile health applications can be used to support patients with chronic and acute diseases in South Africa. Literature identified that medication compliance is low and that a need exists for an intervention to increase compliance. The main goal of this research was to produce a mobile health application to assist medication compliance and support patients with chronic and acute diseases in South Africa and investigate its perceived usefulness. The project made use of two field studies to substantiate its results. The first field study involved patients with chronic diseases and the second one involved patients with acute diseases. The feedback from the first field study and from a literature review was used to redesign the mobile application. The project also investigated the attitude of patients taking medication over a short period of time as well as how such patients compared with those taking chronic medication. The project identified the benefits and disadvantages of using an m-health application to support medication compliance based on the participants’ feedback and behaviour observed in using the application.
- Full Text:
- Date Issued: 2014
Using natural user interfaces to support synchronous distributed collaborative work
- Authors: Potgieter, Timothy Kyle
- Date: 2014
- Subjects: Human-computer interaction User interfaces (Computer systems) Teams in the workplace -- Computer networks
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/10880 , vital:26832
- Description: Synchronous Distributed Collaborative Work (SDCW) occurs when group members work together at the same time from different places together to achieve a common goal. Effective SDCW requires good communication, continuous coordination and shared information among group members. SDCW is possible because of groupware, a class of computer software systems that supports group work. Shared-workspace groupware systems are systems that provide a common workspace that aims to replicate aspects of a physical workspace that is shared among group members in a co-located environment. Shared-workspace groupware systems have failed to provide the same degree of coordination and awareness among distributed group members that exists in co-located groups owing to unintuitive interaction techniques that these systems have incorporated. Natural User Interfaces (NUIs) focus on reusing natural human abilities such as touch, speech, gestures and proximity awareness to allow intuitive human-computer interaction. These interaction techniques could provide solutions to the existing issues of groupware systems by breaking down the barrier between people and technology created by the interaction techniques currently utilised. The aim of this research was to investigate how NUI interaction techniques could be used to effectively support SDCW. An architecture for such a shared-workspace groupware system was proposed and a prototype, called GroupAware, was designed and developed based on this architecture. GroupAware allows multiple users from distributed locations to simultaneously view and annotate text documents, and create graphic designs in a shared workspace. Documents are represented as visual objects that can be manipulated through touch gestures. Group coordination and awareness is maintained through document updates via immediate workspace synchronization, user action tracking via user labels and user availability identification via basic proxemic interaction. Members can effectively communicate via audio and video conferencing. A user study was conducted to evaluate GroupAware and determine whether NUI interaction techniques effectively supported SDCW. Ten groups of three members each participated in the study. High levels of performance, user satisfaction and collaboration demonstrated that GroupAware was an effective groupware system that was easy to learn and use, and effectively supported group work in terms of communication, coordination and information sharing. Participants gave highly positive comments about the system that further supported the results. The successful implementation of GroupAware and the positive results obtained from the user evaluation provides evidence that NUI interaction techniques can effectively support SDCW.
- Full Text:
- Date Issued: 2014
A comparative study of the comfort related properties of commercial apparel fabrics containing natural and man-made fibres
- Authors: Stoffberg, Marguerite Ester
- Date: 2013
- Subjects: Textile fabrics , Materials -- Thermal properties
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10455 , http://hdl.handle.net/10948/d1020931
- Description: The relationship between the fabric parameters, as independent variables, and the comfort related properties, as dependent variables, of commercial suiting fabrics, containing both natural and man-made fibres, have been studied. The fabric parameters measured in the study were mass, thickness, density, and air permeability. The comfort related properties, tested on a Permetest instrument, included water vapour permeability, water vapour resistance, and thermal resistance, with the moisture permeability index being derived. A total of 26 commercial suiting fabrics, covering a wide range of mass, as well as different fibre types and blends and fabric structures, was tested. The fibres covered, included wool, polyester, viscose, and cotton, while the fabric structures covered were 1x1 plain weave, 2x1 twill and 2x2 twill weave. The objectives of this study were to determine the empirical relationships between the measured fabric properties and the measured comfort related properties, and to determine the role, if any, of fibre type and fabric structure, since many claims are made in practice concerning the relative advantages, in terms of comfort, of a specific fibre type or blend, or fabric structure, over others, some of which being supported by research results. Since the fabrics covered, were commercial and were not engineered so that the different fabric parameters (independent variables) and fibre type and blend, as well as fabric structure could be varied independently of each other, the effects of the various fabric parameters on the fabric comfort related properties were determined and quantified by multiple regression analyses (multi-linear and multi-quadratic), and the best fit regression equations, and contribution of each parameter to the overall fit established. It was found that fabric thickness and fabric mass had the largest effect on the comfort related properties as measured here, fabric mass determining, to a large extent, water vapour permeability, and fabric thickness, thermal resistance. The rest of the fabric parameters included in the study had only a relatively small effect on the measured comfort related properties. The influence of fabric parameters, with particular reference to mass and thickness, on the measured comfort related properties, were much greater than that of fibre type or blend, or fabric structure. It was, therefore, concluded from this study, that the fabric parameters, as opposed to the intrinsic characteristics of a particular fibre, whether natural or man-made, largely determined those fabric comfort related properties measured here.
- Full Text:
- Date Issued: 2013
A mathematical investigation of the effects of sexual orientation and HIV status on HPV transmission and vaccination
- Authors: Holtzhausen, Tresia Louisa
- Date: 2013
- Subjects: Virus diseases -- Mathematical models , Cervix uteri -- Cancer -- Treatment , Sexual orientation , Immune response -- Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3946 , vital:20494
- Description: The effect of the inclusion of sexual behaviour, particularly three sexual orientation classes, on the transmission dynamics of HPV and cervical cancer incidence was investigated. A comprehensive literature review of mathematical models of HPV transmission and the natural history of cervical cancer was concluded. A mathematical model using ordinary differential equations was developed, which incorporated the three sexual orientation classes, and a sexual mixing algorithm for modelling the transmission dynamics. Reproduction numbers, determined through a simplified version of the developed model, indicated that the bisexual population could form a bridge between the heterosexual and homosexual population. The level of interaction is determined by the selection preferences of a bisexual individual to form a partnership with an individual of the same or opposite sex. The model was simulated, with parameters based on a South African population and HPV type 16/18, to investigate the effects of HIV status, sexual orientation and various vaccination strategies on HPV transmission and cervical cancer incidence. The results indicated that HIV status is a significant factor when determining cervical cancer incidence. The results regarding vaccination strategies agreed with results from the literature review with a two sex before sexual debut and catch up program the most effective, noting that with increased vaccination coverage of females the marginal impact on cervical cancer incidence of this approach diminished.
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- Date Issued: 2013
An investigation of short-chain fatty acid profiles and influential gastrointenstinal microbiota associated with irritable bowel syndrome
- Authors: Theunissen, Reza
- Date: 2013
- Subjects: Fatty acids in human nutrition , Gastrointestinal system
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10352 , http://hdl.handle.net/10948/d1020943
- Description: Microbiota are present in large numbers and as a diverse population within the gastrointestinal tract. There are approximately 400 different species of microbiota which may be beneficial, harmful or both, but each play an important role in the regulation and modulation of the hosts’ bowel processes (McOrist et al. 2008; Dethlefsen et al. 2008). Many of these colon microbiota allow for saccharolytic fermentation of non-digestible dietary fibres and carbohydrates into by-products and intermediates, followed by a subsequent conversion into short chain fatty acids (SCFAs) (mainly n-butyric acid, propionic acid and acetic acid) each of which play an important role in maintaining colon homeostasis (Topping & Clifton 2001). A balance of ‘good’ microbiota (e.g., Bacteroides spp./ Bifidobacteria spp.) and ‘bad’ microbiota (e.g., Veilonellae) and the optimal production of various SCFAs within the gut could possibly allow for proper functioning of the large intestine and assist in decreasing the onset of various colonic disorders such as Irritable Bowel Syndrome (IBS). The sample group for the study consists of male and female patients, with an average age of 40 to 50 years old, whom of which have been diagnosed with either constipation IBS (C-IBS) or diarrhoea IBS (D-IBS) via the Rome III criteria system for IBS diagnosis. DNA and SCFA extractions were optimised for human stool, colonic fluid and tissue biopsy sample obtained from the aforementioned patients. Optimization steps allowed for starting material with high analysis integrity. Different methods of microbiota analysis, such as ARISA, were investigated; however, real-time qPCR was selected as the best method to identify and quantify specific microbiota. Extracted SCFAs were separated via gas chromatography and identified and quantified via Mass Spectrometry. Significant changes in microbial content and SCFA profiles were found to be associated with healthy and IBS patients. Results obtained would however be influenced by external factors typical of clinical studies of this nature. This study allows for opportunities for future research into understanding IBS.
- Full Text:
- Date Issued: 2013
Anchovy and Sardine in Algoa Bay and their relationship with response variables in two threatened avian predators
- Authors: Potter, Cara-Paige
- Date: 2013
- Subjects: Fishes -- Predators of -- South Africa -- Algoa Bay , Anchovies -- South Africa , Sardines -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10730 , http://hdl.handle.net/10948/d1021130
- Description: Huge populations of sardine and anchovy exist in the four major upwelling systems around the world. These fish are both important ecologically and economically. Pelagic fish dominate the mid trophic level and can exert both a top-down control of zooplankton and a bottom-up control on predatory fish and marine top predators. They also make up a substantial contribution of the world catches in seas around the world where they co-exist in upwelling areas. The fluctuations of sardine and anchovy are largely influenced by recruitment from the larval stage and by the physical environmental forces that determine the planktonic compositions upon which they feed. In southern Africa, the biology and behaviour of two threatened seabird species, African penguins (Spheniscus demersus) and Cape gannets (Morus capensis), are directly influenced by the availability of sardine (Sardinops sagax) and anchovy (Engraulis encrasicolus). This study aimed to provide further insight into the fluctuations of sardine and anchovy in relation to the variability of environmental factors such as wind, sea surface temperature, rainfall and plankton abundance, focusing specifically on Algoa Bay in the Eastern Cape, South Africa. Algoa Bay is particularly important as it is home to the world’s largest African penguin colony and the world’s largest gannetry. Therefore, to further investigate the populations of these two seabird species, the fluctuations of their food source were studied.
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- Date Issued: 2013
Clarifying the influence of human-environment interaction in nature-based adventure tourism in the Tsitsikamma, South Africa
- Authors: Giddy, Julia K
- Date: 2013
- Subjects: Human ecology -- South Africa -- Tsitsikammaberge , Tourism -- South Africa -- Tsitsikammaberge
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10674 , http://hdl.handle.net/10948/d1020782
- Description: Adventure tourism (AT), defined as “a broad spectrum of outdoor touristic activities,often commercialized and involving an interaction with the natural environment away from the participants’ home range and containing elements of risk,” (Hall, 1992, p. 143) is currently one of the fastest growing sub-sectors of the tourism industry (Buckley 2010). Because it has emerged relatively recently as a field of study, a number of scholars have called for ongoing research in the area, see Swarbrooke (2003), Pomfret (2006), Buckley (2010), Rogerson (2007), and Williams & Soutar (2005). Much of this research, to date, has focused on marketing, injury caused by AT participation, environmental impacts, and the broad notion of “risk” associated with AT. The problem is that little of this work has focused on the significance of the environment in adventure tourism – an important element inherent in its definition. Thus, this thesis aims to move beyond a general risk-based analysis of AT, and focus on the role of the environment. This is done through a human-environment interaction approach undertaken in Tsitsikamma Village where five adventure tourist operations are based. The first step in operationalizing this approach was to develop a conceptual framework that integrated adventure tourism into a general framework on humanenvironment interaction. The second step was to use a research instrument which enabled one to examine the influence of the environment on human motivations and adventure tourism experiences, and not only the influence of humans on the environment. The former was accomplished through questionnaires based on external, environmental elements that attract adventure tourists as well as inherent personality traits impel such tourists to participate in AT. The latter, based on interviews and participant perceptions, sought to establish the significance of impacts on the environment as well as initiatives taken by AT companies to minimize environmental damage. The findings show that although risk/thrill does play a role, AT motivations and experiences are complex and multidimensional. The environment does significantly influence both motivations and even more so AT experiences. Furthermore, there are distinct differences between the motivations and experiences of participants in different types of AT activities, indicating that generalizing the industry as whole neglects these significant differences. In terms of influences on the environment, the results show that most AT operators in the Tsitsikamma have some consideration for environmental protection and take some initiatives to minimize environmental damage, though the degree to which this occurs differs significantly. Furthermore, activity participants do not believe that the activities have a strong negative impact on the environment, though the majority acknowledge small impacts. The types of impacts observed by participants vary significantly between companies. This thesis demonstrates the manner in which the two-way relationship between humans and the environment manifests itself in the commercial AT industry. The result is a well-rounded examination of the influence of human-environment interaction on AT participants.
- Full Text:
- Date Issued: 2013
Compound distribution models for athletics records
- Authors: Hanly, Erin
- Date: 2013
- Subjects: Athletics , Statistics -- Sports , Forecasting -- Sports
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10105 , http://hdl.handle.net/10948/d1018609
- Description: World records in athletics capture the attention of both the general public and the academic community. Athletics records provide a wealth of quantifiable data, which represent the pinnacle of human ability at the time of the record. This research discusses modelling the progression of athletics world records using a compound distribution model which is found in actuarial statistics. Compound distributions allow for the simultaneous modelling of the frequency of record breaking and of the amount by which the record is improved at each record-breaking performance. A number of assumptions accompany the use of the compound distribution model. This research evaluates the athletics data for adherence to these assumptions, before carrying out distribution-fitting and goodnessof-fit testing. Forecasts of future performance are obtained by means of a simulation method. The forecasts obtained from the compound model are compared to forecasts obtained from non-linear models which have been proposed in literature. This research focuses on short-term forecasts, however, a modification to the compound model which allows for longer-term forecasts is also illustrated.
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- Date Issued: 2013
Cretaceous dyke swarms and brittle deformation structures in the upper continental crust flanking the Atlantic and Indian margins of Southern Africa, and their relationship to Gondwana break-up
- Authors: Muedi, Thomas Tshifhiwa
- Date: 2013
- Subjects: Dikes (Geology) -- Africa, Southern , Joints (Geology) -- Africa, Southern , Gondwana (Continent)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10675 , http://hdl.handle.net/10948/d1020896
- Description: Permanent brittle deformation of rocks of the upper crust is often manifested in the growth of fractures, or sliding along fractures, which may subsequently be intruded by magma and other fluids. The brittle deformation structures described here include faults, joints and dykes. Brittle deformation structures along passive continental margins result from continental fragmentation and related uplift, as is seen around the southern African margins in response to Gondwana break-up. In many cases the fragmentation is accompanied by significant magmatic events, for example the Cretaceous mafic dyke swarms that form major components of the South Atlantic Large Igneous Province (LIP) and originated during the break-up of West Gondwana (Africa and South America). The magmatic events accompanying the break-up of Gondwana resulted in crustal extension and the formation of joint systems and dyke swarms that exhibit distinct geometric features that appear to display fractal patterns. This work analyses the relationship between the Henties Bay-Outjo Dyke Swarm (HOD) on the west coast of Namibia, and the Ponta Grossa Dyke Swarm (PG) on the coast of Brazil, both of which formed ca. ~130 Ma, to test for their co-linearity and fractal geometry before and during West Gondwana break-up. This was achieved by reconstructing Gondwana‘s plates that contained the PG and HOD swarms, using ArcGIS and Gplates software. The dyke analyses was complemented with a comparative study of joints of the Table Mountain Group quartzites (TMG, ca. 400 Ma) in the Western Cape Province and Golden Valley Sill (GVS, ca. 180 Ma) in the Eastern Cape Province, to compare their fractal patterns and possible relationship. Mapping of joints was carried out in the field with the use of a compass and GPS. The HOD trend is positioned largely NNE > NE, but a NW dyke trend is also common. The dominant joints in the TMG trend NNW > WSW and the GVS joints trend WNW > NNE and others. The GVS and HOD orientations appear strongly correlated, while TMG shows no simple orientation correlation with GVS and HOD. The lack of correlation is attributed to the TMG‘s formation in different host-rocks with variable anisotropy and/or the presence of different mechanical processes acting at a different time in geological history. All mapped dykes and joints were analysed to test for fractal geometry. The fractal dimension results of about 18605 HOD dykes from microscopic to mega scale (0.1 mm – 100 km) shows fractal patterns that range between Df = 1.1 to 1.9; and the fractal dimension of about 1716 joints in the TMG and about 1026 joints in the GVS at all scales range between ca. Df = 1.6 to 1.9. The similarity of the fractal patterns indicates that joints and dykes may have formed in response to similar tectonic stress events; and similar orientations may indicate that joints pre-dated the dyke intrusions. However, the data also indicate that dykes are not always related to pre-existing joints.
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- Date Issued: 2013
Designing multi-touch tabletop interaction techniques to support co-located Group Information Management
- Authors: Ditta, Mohammed Ali
- Date: 2013
- Subjects: Groupware (Computer software) , Teams in the workplace -- Data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10493 , http://hdl.handle.net/10948/d1020639
- Description: Co-located group information management (GIM) is a form of groupware with the aim of enabling users to collaboratively find, store, maintain, organise and share personal and/or group information in support of a group activity. Existing systems aimed at partially supporting GIM activities have been implemented on single user devices. These systems make use of asynchronous communication that may hinder collaboration by misinterpretation, information leaks, etc. Few systems exist, with limited functionality, that support co-located GIM. Multi-touch tabletop interaction has given rise to a new approach for supporting Computer Supported Cooperative Work (CSCW). Multi-touch tabletops allow multiple users to naturally interact with a computer device using a shared display and gesture interaction. The tabletop environment also enables users to sit in a natural environment and synchronously communicate without bulky desktops or laptops. Multi-touch tabletops provide the hardware necessary to support co-located GIM. Existing multi-touch interaction techniques were analysed and proved insufficient to support the advanced functional requirements of GIM. The goal of this research was therefore to support co-located GIM by designing new multi-touch tabletop interaction techniques. An architecture was proposed to support co-located GIM with new multi-touch interaction techniques. A software prototype was developed based on the proposed architecture to facilitate the main activities of GIM and to collaboratively compile documents. The prototype was named CollaGIM (Colla – collaborative, GIM – group information management). CollaGIM supports the main activities of GIM using natural gesture interaction on a multi-touch tabletop. An evaluation of the software was conducted by means of a user study where 15 teams of two people participated. High task success rates and user satisfaction results were achieved, which showed that CollaGIM was capable of supporting co-located GIM using the new multi-touch tabletop interaction techniques. CollaGIM also positively supported collaboration between users.
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- Date Issued: 2013
Diet and foraging distribution of gentoo penguins pygoscelis papua at Cow Bay, Falkland Islands
- Authors: Handley, Jonathan Murray
- Date: 2013
- Subjects: Gentoo penguin -- Food -- Falkland Islands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10724 , http://hdl.handle.net/10948/d1020377
- Description: Knowledge of diet and distribution in marine top predators is critical in interpreting their ecological role. Furthermore, this information is required for effective management and conservation of these species. For gentoo penguins at the Falkland Islands a previous overlap in dietary items with commercial fisheries was recognised. Despite this the at-sea distribution has been poorly studied and only at a few localities. Therefore, this thesis looks to broaden the knowledge of foraging ecology for gentoo penguins at another site in the archipelago, Cow Bay. The aim was firstly, through stomach content analysis, to determine if diet changed over a large temporal scale (2002/03/04 – 2011/12/13), and between the chick guard and crèche periods of chick rearing. Secondly, through GPS loggers, to assess distribution at sea during the incubation and chick guard periods (2012/13). Additionally, foraging ecology between genders was investigated. Gentoo penguins at Cow Bay foraged primarily on fish (66-99 percent) throughout the entire study period. The principle prey item by mass was Patagonotothen spp., considered previously as discard by fisheries but now an important commercial resource, for all periods (47-78 percent) except that of the 2012/13 crèche period (19 percent). During this period Sprattus fugensis made up the bulk of the diet (52 percent). Cephalopods, particularly Loligo gahi (1-24 percent), were also prominent in the diet and crustaceans contributed negligibly. The diet indicated that gentoo penguins are capable of both a benthic and pelagic feeding strategy which likely reflects changes in local prey abundance. Birds typically conducted foraging activities during daylight hours with greater trip duration, path length, maximum distance and area utilised during the incubation period than the guard. All trips were confined to the continental shelf and within the boundaries of a marine management zone, the Falkland Islands Interim Conservation Zone (FICZ). Males and females fed on the same size and composition of prey items. Trip duration, path length and maximum distance from the colony were not significantly different, although males foraged in a slightly larger area than females marginally to the north. As at-sea distribution was confined within the FICZ this management area provides protection to food resources of gentoo penguins breeding at Cow Bay. At this site, the population is increasing, likely associated with increased prey availability as evidenced by record catches of Patagonotothen spp. in recent years at the Falkland Islands. Continued long term monitoring of gentoo penguin diet and fishery yields to allow detection of possible competition in the future is recommended. As marine sentinels, on-going monitoring of gentoo penguin populations at the Falkland Islands is likely to provide early warning signs of reduced prey availability.
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- Date Issued: 2013
Dysfunctional facilities management service provision in an outsource environment
- Authors: Otoo, Ernest Kweku
- Date: 2013
- Subjects: Facility management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9725 , http://hdl.handle.net/10948/d1019717
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- Date Issued: 2013
Environmentally friendly dyeing and finishing
- Authors: Dayla, Mackraj
- Date: 2013
- Subjects: Dyes and dyeing -- Knit goods -- South Africa , Textile finishing -- South Africa , Bleaching industry -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10454 , http://hdl.handle.net/10948/d1020776
- Description: The textile industry in South Africa is a significant contributor to the chemical load that public wastewater treatment plants have to process, and the discharge of toxic substances, especially to the aquatic environment. In order to address this issue at factory level, the processes at a textile plant, JMV Textiles were chosen for investigation into the possibilities of minimization of discharges of harmful substances into the environment. The study followed the principles of cleaner production, and the processes that were investigated and revised were: The conventional peroxide bleaching process employed a peroxide stabilizer that did not biodegrade easily. The bleaching process was changed, so that the prevailing conditions in the fabric and dyebath facilitated bleaching without the addition of peroxide stabilizer, and also reduced the alkali and energy requirements. Polyester‐viscose fabric was pretreated by bleaching with hydrogen peroxide, which seemed to be unnecessarily rigorous, because polyester and viscose, unlike natural fibres, are relatively clean and have good whiteness in comparison with natural fibres. The proposed alternate pretreatment was a scour with detergent and alkali. The pretreatment for all polyester‐cotton fabrics was also a hydrogen peroxide bleach. Due to the ability of medium and dark shades to mask the natural tint of cotton fibres, a simpler alternate pretreatment, consisting of an alkaline scour with sequestering agent, was trialled. An unacceptable proportion of the dyeings on polyester was rejected for dye‐stains and dye‐marks. A possible solution exploited the properties of using the finishing auxiliary chemical to alleviate dye‐stains and dye‐marks during the dyeing stage, instead of using the chemical after dyeing. The highly toxic carrier that was used to facilitate level dyeing of polyester fibres that had unacceptable variation in their dyeing properties, was replaced by a less toxic carrier. The formulation for dyeing polyester was simplified to eliminate the auxiliary chemicals that were not essential to the dyeing process. Pale reactive dyed shades on cellulose and polyester‐cellulose were washed off only with hot water instead of detergent. The revised procedures consequential to the study, offered significant environmental benefits by reducing the concentration and volume of effluent produced, substituting a highly toxic carrier with a less toxic one and saving energy and water. Implementation of the suggested changes also offered financial benefits. The management of the factory, however, accepted and implemented some changes, but wanted further investigations for others and a phased approach to the other suggested changes.
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- Date Issued: 2013
Evaluating the effect of microalgae biomass on the combustion of coal
- Authors: Ejesieme, Obialo Vitus
- Date: 2013
- Subjects: Co-combustion , Coal -- Combustion , Biomass -- Combustion
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10435 , http://hdl.handle.net/10948/d1020641
- Description: In this work the combustion characteristics of coal, charcoal, microalgae biomass and blends between these three components were evaluated by means of non-isothermal thermogravimetry. Blends between coal, charcoal and microalgae biomass were made according to the specifications of a D-optimal mixture design so as to be able to model interactions between the three components with maximum precision despite multiple constraints built into the design. These constraints specified that coal can have a minimum value of 70 mass percent in any blend, while microalgae can have a maximum value of 20 mass percent. While coal and charcoal were blended by mixing the two respective dry components, microalgae biomass was incorporated into the blends by first absorbing microalgae onto fine coal from concentrated slurry of the microalgae in water. The microalgae in these blends were therefore intimately associated with the coal. This approach differed substantially from the normal practice of preparing coal – biomass blends (which are usually dry-mixed as for coal – charcoal blends). Proximate analyses of the starting materials showed that the microalgae biomass has a significantly higher volatile matter: fixed carbon content than both coal and charcoal, which should improve the combustion of these materials by providing a more stable combustion flame. Analyses of the thermogravimetric data obtained showed that coal and charcoal have much simpler combustion profiles than microalgae biomass for which five different thermal events could be observed in the DTG combustion profile. Qualitative kinetic analyses showed that the combustion of coal and charcoal follows first-order kinetics, but for microalgae biomass combustion, the first two combustion stages appear to follow first-order kinetics. The TG and DTG profiles for coal, charcoal, microalgae and blends of these three components were used to derive values for the so-called comprehensive combustion property index (S-value), which provides a combined measure of the ease of ignition, rate of combustion, and burn-out temperature. The S-values so obtained were used as response variable for the construction of a response surface model in the experimental domain investigated. Following statistical validation of the response surface model, the model was used to predict an optimum S-value or a blend that would display optimum combustion behaviour. Two optimum blends were obtained from the optimisation process, one in which only charcoal is added to coal, and one in which only microalgae is added to coal. Adding both charcoal and microalgae produced an antagonistic effect compared to when only one of these are used. Qualitative kinetic analyses of the combustion data of blends indicate that blends of coal and charcoal combust in a manner similar to the individual components (hence following first-order kinetics), but blends of coal and microalgae follow more complex kinetics despite the fact that the combustion profile is visibly more simple compared to the combustion profile for microalgae alone.
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- Date Issued: 2013