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Development, manufacture and assessment of Clobetasol 17-propionate cream formulations

  • Authors: Fauzee, Ayeshah Fateemah Beebee
  • Date: 2011
  • Subjects: Adrenocortical hormones , Adrenocortical hormones -- Physiological effect , Adrenocortical hormones -- Testing , Drugs -- Testing , Drugs -- Development , Dermatopharmacology
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:3856 , http://hdl.handle.net/10962/d1013324
  • Description: Eczema or dermatitis is the most common dermatological condition accounting for one-third of all diagnoses in the total population surveyed in South Africa. The prevalence of seborrhoeic dermatitis, extreme photodermatitis and severe psoriasis has increased markedly over the last decade and this increase may be ascribed to the HIV epidemic, first diagnosed in South Africa in 1982. Potent innovator corticosteroids, such as clobetasol 17-propionate (CP) that are used to treat skin disorders, are expensive and there is therefore a need for the production of generic topical corticosteroid products. Formulation and manufacturing processes can be challenging aspects for formulation scientists to produce a robust product that will elicit an appropriate and desirable pharmacokinetic-pharmacodynamic profile. Laboratory scale CP creams were manufactured using different concentrations of Gelot® 64 and propylene glycol in order to establish a composition that would produce a formulation, with similar physical and chemical characteristics and in vitro release profile as an innovator product, Dermovate®. These formulations were assessed in terms of their viscosity, spreadability, pH, content uniformity and in vitro release characteristics using a Franz diffusion cell apparatus. A formulation containing 3% w/w Gelot® 64 and 46% v/v propylene glycol (CPLS-02) was found to exhibit similar viscosity and spreadability characteristics and released CP in a manner similar to Dermovate®. The mechanism of drug release was evaluated using mathematical models such as zero order, first order and Higuchi models. In addition, the in vitro release profiles were characterised by use of difference (f1) and similarity (f2 and Sd) factors. A scale-up formulation with the same % w/w composition as the laboratory scale was also investigated following manufacture using a Wintech® cream/ointment mixer. A Central Composite Design approach was used to investigate the effect of process variables on the performance of the scale-up cream formulations. The homogenisation speed, anchor speed, homogenisation time and cooling time were the process variables investigated. Thirty scale-up batches were manufactured and analysed in terms of their viscosity, spreadability, pH, % drug content and cumulative % drug released per unit area over 72 hours. Model fitting using Design-Expert® software was undertaken and revealed that a correlation between the process variables and the cream responses was most suitably described by quadratic polynomial relationships. The homogenisation speed had the most significant effect on the quality of the scale-up formulations, whereas the anchor speed had a secondary effect on the measured responses, for the formulations investigated. The qualitative interpretation and statistical analysis of the in vitro release data from the scale-up formulations using ANOVA and the f1, f2 and Sd factors revealed that one scale-up batch (CPSU-04), for which the process variables were a homogenisation speed of 1900 rpm, an anchor speed of 35 rpm, a homogenisation time of 100 minutes and a cooling time of 100 minutes, released CP at a similar rate and extent to Dermovate®. A diffusion-controlled mechanism appeared to be predominant in these formulations. A human skin blanching study, using both visual and chromameter assessments, was performed to establish whether batch CPSU-04 was bioequivalent to Dermovate®. The bioequivalence of the selected scale-up formulation to Dermovate® was confirmed, following the calculation of a 90% CI.
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  • Date Issued: 2011

Die outobiografiese kode in Antjie Krog se poëtiese oeuvre

  • Authors: Botha, Maria Elizabeth
  • Date: 2011
  • Subjects: Krog, Antjie -- Criticism and interpretation , Autobiography -- History and criticism , Afrikaans poetry -- 20th century -- History and criticism
  • Language: Afrikaans
  • Type: Thesis , Doctoral , DLitt
  • Identifier: vital:8444 , http://hdl.handle.net/10948/1534 , Krog, Antjie -- Criticism and interpretation , Autobiography -- History and criticism , Afrikaans poetry -- 20th century -- History and criticism
  • Description: This study primarily investigates the autobiographical code in Antjie Krog's poetical oeuvre, spanning from 1970 to the present. Krog's poetry collections may be read as offering life writing through poetry, while the prose works mostly present the reader with a mixture of autobiographical fact plus creative reworkings of fact and fiction. Even though her 10 volumes of poetry follow her biological development from young girl to grandmother, uncertainty still exists about about where truth ends and fiction begins in this poet and autobiographer's interwoven tapestry of multiple and varied perspectives. Furthermore, autobiographical (as utilised and adapted in Krog's oeuvre, in combination with the conventioans from other genres), offers a variety of creatively innovative, experimental strategies and possibilities exploited adroitly by Krog. Reading her poetry with the focus on autobiographical markers leads to another, mostly untapped, dimension of interpretation. This literary approach is in stark contrast to the approach prescibed by N.P. van Wyk Louw in "Die 'mens' agter die boek" ["The 'Person' behind the Book] (1956), in which he states clearly that a text should be interpreted as not "about the human behind the text". To a large extent Krog as poet is inviting the reader to consciously break the taboo that Louw placed on the reader intent on "searching the actual person behind the text". My hypothesis is that in Krog's poetry there is a distinct interrelationship between the perceptions, experiences and sensual impressions of the lyrical "I" in the poems and that of the authobiographical "I" writing. It would be irresponsible to declare the poet and the speaker as one and the same, but in instances where the poet purposefully integrates autobiographical elements into her poems, she is implicitly requesting the reader to interpret her work in this way. This fictive and implicit request is referred to by Philippe Lejeune as the autobiographical poet. Krog's poetry can be divided into four categories: "direct autobiographical", "indirect autobiographical", "universal" and "general" poems. The first category involves criteria that are linked to the poet, such as the use of the names, initials and dates. Indirect autobiographical poems can be read against the background of knowledge (previously published information) about the poet. Poetry with no apparent autobiographical element, but with universal themes such as love, loss and transience, fall into the third category of "universal" poetry. If poems do not fit into the mentioned categories, they are deemed "general".
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  • Date Issued: 2011

Differential expression and regulation of sucrose transporters in rice (Orzya sativa L, cv Nipponbare) during environmental stress conditions

  • Authors: Ibraheem, Omodele
  • Date: 2011
  • Subjects: Crops -- Effect of stress on , Plant molecular genetics , Gene expression , Sucrose , Rice
  • Language: English
  • Type: Thesis , Doctoral , PhD (Biochemistry)
  • Identifier: vital:11249 , http://hdl.handle.net/10353/330 , Crops -- Effect of stress on , Plant molecular genetics , Gene expression , Sucrose , Rice
  • Description: Plant productivity is greatly affected by environmental stresses such as drought, salinity and insect herbivory. Plants respond and adapt to these stresses by exhibiting physiological as well as biochemical changes at the cellular and molecular levels in order to survive. Expression of a variety of genes which encode numerous membrane transporters have been demonstrated to be induced by these stresses in a variety of plants. The nutritional status of plants is controlled by these transporters, which are regulated by the transcription of the corresponding genes. In spite of these adverse stress effects on agricultural yield, only a few studies have focused on gene transcriptional and translational regulation of membrane transporters during environmental stress situations. Rice, like other plants, contains a number of sucrose transporters encoded by a family of genes. However, detailed knowledge of their roles, localization and regulation during environmental stress conditions is lacking. Bioinformatic tools were used to identify putative cis-acting regulatory elements that may be involved in the regulation of rice and Arabidopsis thaliana sucrose transporters. The possible cis-acting regulatory elements were predicted by scanning genomic sequences 1.5 kbp upstream of the sucrose transporter genes translational start sites, using Plant CARE, PLACE and Genomatix Matinspector professional data bases. Several cis-acting regulatory elements that are associated with plant development, plant hormonal regulation and stress response were identified, and were present in varying frequencies within the 1.5 kbp of 5′ regulatory region. The putative cis-acting regulatory elements that possibly are involved in the expression and regulation of sucrose transporter gene families in rice and Arabidopsis thaliana during cellular development or environmental stress conditions were identified as: A-box, RY, CAT, Pyrimidine-box, Sucrose-box, ABRE, ARF, ERE, GARE, Me-JA, ARE, DRE, GA-motif, GATA, GT-1, MYC, MYB, W-box, and I-box. Expression analysis was used to elucidate the role of rice (Oryza sativa L. cv Nipponbare) sucrose transporter (OsSUT) genes during drought and salinity treatments of three week old rice plants ( at four leaf stage) over a 10 days. Among the five rice OsSUT genes identified, only OsSUT2 was observed to be progressively up-regulated during drought and salinity treatments, while OsSUT1, OsSUT4 and OsSUT5 were expressed at low levels, and OsSUT3 showed no detectable transcript expression. Sucrose transport will be essential to meet the cellular energy demands and also for osmoprotectant activities during drought and salinity stresses. It therefore indicates that OsSUT2 which facilitates transport of sucrose from photosynthetic cells will be III essential for rice plants to cope with drought and salinity stresses, and cultivars with a higher OsSUT2 expression should be able to tolerate these environmental stresses better. The role of OsSUT in assimilate transport during rusty plum aphids (Hysteroneura setariae; Thomas) infestation on the leaves of three week old rice (Orzya sativa L. cv Nipponbare) cultivar plants, over a time-course of 1 to 10 days of treatments, was also examined by combination of gene expression and β-glucuronidase (GUS) reporter gene analysis. Real Time PCR analysis of the five OsSUT genes revealed that the expression of OsSUT1 was progressively up-regulated during the course of aphid infestation. OsSUT2 and OsSUT4 expression were comparatively low in both the control and treated plants. OsSUT5 showed no clear difference in transcript expression in both control and treated plants, while no detectable transcript expression of OsSUT3 could be found. The up-regulation of OsSUT1 gene was verified at protein level by western blot analysis in both the control and treated plants. OsSUT1 protein expression was found to increase with time during aphid infestation. A similar trend was noticeable in the control plants, however at a lower expression level. These demonstrate that the cellular expression of OsSUT1is regulated by both developmental and environmental factors. OsSUT1-promoter:::GUS reporter gene expression was observed within the vascular parenchyma and/or companion cells associated with phloem sieve elements of the large and small bundles in the phloem tissues of the flag leaf blade regions where feeding aphids were confined, which progressively increased with time of infestation. It is suggested that OsSUT1 may primarily play an essential role in phloem transport of assimilate to wounded tissues from adjacent health tissues or may be involved in the retrieval of assimilate back into the phloem to minimize loss caused by the infestation. Some OsSUT1-promoter:::GUS expression was also found in the metaxylem at 10 days after infestation, which could signify a recovery system in which sucrose lost into the xylem as a result of aphids feeding are retrieved back into the phloem through the vascular parenchyma. This was supported by the exposure of cut ends of matured OsSUT1-promoter:::GUS rice plant leaf to 2% sucrose solution. OsSUT1-promoter:::GUS expression was observed within the protoxylem, xylem and phloem parenchyma tissues. This indicates that sucrose translocating within the xylem tissues are retrieved into the phloem via the OsSUT1 localized within the parenchyma tissues. In conclusion, the differential expression and regulation of rice (Orzya sativa L. cv Nipponbare) sucrose transporters as reported here suggest that OsSUT2 and OsSUT1 were constitutively expressed compared to other rice sucrose transporters during drought and salinity, and rusty plum aphids (Hysteroneura setariae; Thomas) infestation stresses respectively. Thus, the expression and regulation of the sucrose transporters could be related to the physiological and nutritional requirements of the cells during plant developmental or environmental stress state that allows their differential expression.
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  • Date Issued: 2011

Digital forensic model for computer networks

  • Authors: Sanyamahwe, Tendai
  • Date: 2011
  • Subjects: Computer crimes -- Investigation , Evidence, Criminal , Computer networks -- Security measures , Electronic evidence , Forensic sciences , Internet -- Security measures
  • Language: English
  • Type: Thesis , Masters , MCom (Information Systems)
  • Identifier: vital:11127 , http://hdl.handle.net/10353/d1000968 , Computer crimes -- Investigation , Evidence, Criminal , Computer networks -- Security measures , Electronic evidence , Forensic sciences , Internet -- Security measures
  • Description: The Internet has become important since information is now stored in digital form and is transported both within and between organisations in large amounts through computer networks. Nevertheless, there are those individuals or groups of people who utilise the Internet to harm other businesses because they can remain relatively anonymous. To prosecute such criminals, forensic practitioners have to follow a well-defined procedure to convict responsible cyber-criminals in a court of law. Log files provide significant digital evidence in computer networks when tracing cyber-criminals. Network log mining is an evolution of typical digital forensics utilising evidence from network devices such as firewalls, switches and routers. Network log mining is a process supported by presiding South African laws such as the Computer Evidence Act, 57 of 1983; the Electronic Communications and Transactions (ECT) Act, 25 of 2002; and the Electronic Communications Act, 36 of 2005. Nevertheless, international laws and regulations supporting network log mining include the Sarbanes-Oxley Act; the Foreign Corrupt Practices Act (FCPA) and the Bribery Act of the USA. A digital forensic model for computer networks focusing on network log mining has been developed based on the literature reviewed and critical thought. The development of the model followed the Design Science methodology. However, this research project argues that there are some important aspects which are not fully addressed by South African presiding legislation supporting digital forensic investigations. With that in mind, this research project proposes some Forensic Investigation Precautions. These precautions were developed as part of the proposed model. The Diffusion of Innovations (DOI) Theory is the framework underpinning the development of the model and how it can be assimilated into the community. The model was sent to IT experts for validation and this provided the qualitative element and the primary data of this research project. From these experts, this study found out that the proposed model is very unique, very comprehensive and has added new knowledge into the field of Information Technology. Also, a paper was written out of this research project.
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  • Date Issued: 2011

Dimethylglyoxime based ion-imprinted polymer for the determination of Ni(II) ions from aqueous samples

  • Authors: Rammika, Modise , Darko, Godfrey , Tshentu, Zenixole R , Sewry, Joyce D , Torto, Nelson
  • Date: 2011
  • Language: English
  • Type: Article
  • Identifier: vital:6590 , http://hdl.handle.net/10962/d1004173
  • Description: A Ni(II)-dimethylglyoxime ion-imprinted polymer {Ni(II)-DMG IIP} was synthesised by the bulk polymerisation method. The morphology of the Ni(II)-DMG IIP and non-imprinted polymer were observed by scanning electron microscopy and the chemical structures were evaluated by infrared spectroscopy. Selectivity of the Ni(II)-DMG IIP was studied by analysing, using an inductively coupled plasma-optical emission spectrometer, for Ni(II) ions that were spiked with varying concentrations of Co(II), Cu(II), Zn(II), Pd(II), Fe(II), Ca(II), Mg(II), Na(I) and K(I) in aqueous samples. The studies revealed Ni(II) recoveries ranging from 93 to 100% in aqueous solutions with minimal interference from competing ions. Enrichment factors ranged from 2 to 18 with a binding capacity of 120 μg∙g−1. Co(II) was the only ion found to slightly interfere with the determination of Ni(II). Selectivity studies confirmed that the Ni(II)-DMG IIP had very good selectivity, characterised by %RSD of less than 5%. The limits of detection and quantification were 3x10-4 μg∙mℓ−1 and 9x10-4 μg∙mℓ−1, respectively. The accuracy of the method was validated by analysing a custom solution of certified reference material (SEP-3) and the concentration of Ni(II) obtained was in close agreement with the certified one. The Ni(II)-DMG IIP was successfully employed to trap Ni(II) ions from a matrix of sea, river and sewage water. It is believed that the Ni(II)-DMG IIP has potential to be used as sorbent material for pre-concentration of Ni(II) ions from aqueous solutions by solid-phase extraction.
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  • Date Issued: 2011

Dismissal law in the education sector

  • Authors: Myeki, Mfundo
  • Date: 2011
  • Subjects: Industrial relations -- South Africa , Labor laws and legislation , Employees -- Dismissal of -- Law and legislation , Labor contract -- South Africa
  • Language: English
  • Type: Thesis , Masters , LLM
  • Identifier: vital:10213 , http://hdl.handle.net/10948/1567 , Industrial relations -- South Africa , Labor laws and legislation , Employees -- Dismissal of -- Law and legislation , Labor contract -- South Africa
  • Description: This treatise will therefore critically discuss fairness requirements in dismissal law within the context of the education sector from: i) the perspective of a dismissed employee; and ii) the perspective of an employer who wishes to dismiss employees fairly; and iii) the perspective of a deemed dismissal. It will be proper to flow this discussion from the premises of what should be considered procedural and substantive fairness in dismissals.
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  • Date Issued: 2011

Distinguished women in Chemistry Award (PACN)

  • Authors: Nyokong, Tebello
  • Date: 2011
  • Identifier: vital:7223 , http://hdl.handle.net/10962/d1005901
  • Description: Distinguished Women in Chemistry Award as part of the Pan Africa Chemistry Network (PACN) and Royal Society of Chemistry (RSC) International Year of Chemistry Celebration of the 100th Anniversary of Marie Curie’s Nobel Award in Chemistry.
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  • Date Issued: 2011

Distributing intelligence in the wireless control of a mobile robot using a personal digital assistant

  • Authors: Ophoff, Madri
  • Date: 2011
  • Subjects: Mobile robots , User interfaces (Computer systems)
  • Language: English
  • Type: Thesis , Masters , MTech
  • Identifier: vital:9598 , http://hdl.handle.net/10948/1355 , Mobile robots , User interfaces (Computer systems)
  • Description: Personal Digital Assistants (PDAs) have recently become a popular component in mobile robots. This compact processing device with its touch screen, variety of built-in features, wireless technologies and affordability can perform various roles within a robotic system. Applications include low-cost prototype development, rapid prototyping, low-cost humanoid robots, robot control, robot vision systems, algorithm development, human-robot interaction, mobile user interfaces as well as wireless robot communication schemes. Limits on processing power, memory, battery life and screen size impact the usefulness of a PDA in some applications. In addition various implementation strategies exist, each with its own strengths and weaknesses. No comparison of the advantages and disadvantages of the different strategies and resulting architectures exist. This makes it difficult for designers to decide on the best use of a PDA within their mobile robot system. This dissertation examines and compares the available mobile robot architectures. A thorough literature study identifies robot projects using a PDA and examines how the designs incorporate a PDA and what purpose it fulfils within the system it forms part of. The dissertation categorises the architectures according to the role of the PDA within the robot system. The hypothesis is made that using a distributed control system architecture makes optimal use of the rich feature set gained from including a PDA in a robot system’s design and simultaneously overcomes the device’s inherent shortcomings. This architecture is developed into a novel distributed intelligence framework that is supported by a hybrid communications architecture, using two wireless connection schemes. A prototype implementation illustrates the framework and communications architecture in action. Various performance measurements are taken in a test scenario for an office robot. The results indicate that the proposed framework does deliver performance gains and is a viable alternative for future projects in this area.
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  • Date Issued: 2011

Diverse pollination systems of the twin-spurred orchid genus Satyrium in African grasslands

  • Authors: Johnson, S.D , Peter, C.I , Ellis, A.G , Boberg, E , Botes, C , Van der Niet, T
  • Date: 2011
  • Language: English
  • Type: Article
  • Identifier: vital:6558 , http://hdl.handle.net/10962/d1006025 , http://dx.doi.org/10.1007/s00606-010-0411-1
  • Description: The large terrestrial orchid genus Satyrium underwent evolutionary radiations in the Cape floral region and the grasslands of southern and eastern Africa. These radiations were accompanied by tremendous diversification of the unusual twin-spurred flowers that characterize the genus, but pollination data required to interpret these patterns of floral evolution have been lacking for grassland species in the genus. Here we document pollinators, nectar properties, and levels of pollination success for 11 grassland Satyrium species in southern and south-central Africa. Pollinators of these species include bees, beetles, butterflies, hawkmoths, noctuid moths, long-proboscid flies, and sunbirds. Most species appear to be specialized for pollination by one functional pollinator group. Long-proboscid fly pollination systems are reported for the first time in Satyrium (in S. macrophyllum and a high-altitude form of S. neglectum). Floral morphology, especially spur length and rostellum structure, differs markedly among plants with different pollinators, while nectar volume, concentration, and sugar composition are fairly uniform across species. Most taxa exhibited high levels of pollination success (>50% of flowers pollinated), a trend that can be attributed to the presence of nectar in the twin spurs.
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  • Date Issued: 2011

Do budget deficits crowd out private investment?: an analysis of the South African Economy

  • Authors: Biza, Rumbidzai Aimee
  • Date: 2011
  • Subjects: Individual investors -- South Africa , Budget deficits -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10353/24956 , vital:63750
  • Description: This dissertation investigates whether budget deficits crowd out or crowd in private investment in South Africa, using quarterly South African data covering the period 1994 to 2009. South Africa has been experiencing unprecedented budget deficits since the 1960s and the study investigates how this has impacted on the country’s private investment demand. An empirical model linking private investment to its theoretical variables is specified and used to assess the quantitative effects of budget deficits on private investment. This study augments the co-integration and vector auto-regression (VAR) analysis with impulse response and variance decomposition analyses to provide robust long run and short run dynamic effects on private investment. The variables have been found to have a long run relationship with private investment. Results suggest that budget deficits significantly crowds out private investment. These results corroborate the theoretical predictions and are also supported by previous studies. , Thesis (MCom) -- Faculty of Management and Commerce, 2011
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  • Date Issued: 2011

Does the growth of structure affect our dynamical models of the Universe? The averaging, backreaction, and fitting problems in cosmology

  • Authors: Clarkson, C , Ellis, G , Larena, Julien , Umeh, O
  • Date: 2011
  • Language: English
  • Type: Article
  • Identifier: vital:6791 , http://hdl.handle.net/10962/d1006944
  • Description: Structure occurs over a vast range of scales in the Universe. Our large-scale cosmological models are coarse-grained representations of what exists, which have much less structure than there really is. An important problem for cosmology is determining the influence the small-scale structure in the Universe has on its large-scale dynamics and observations. Is there a significant, general relativistic, backreaction effect from averaging over structure? One issue is whether the process of smoothing over structure can contribute to an acceleration term and so alter the apparent value of the cosmological constant. If this is not the case, are there other aspects of concordance cosmology that are affected by backreaction effects? Despite much progress, this 'averaging problem' is still unanswered, but it cannot be ignored in an era of precision cosmology, for instance it may affect aspects of baryon acoustic oscillation observations.
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  • Date Issued: 2011

Drug transport mechanisms from carbopol/eudragit verapamil sustained-release tablets

  • Authors: Khamanga, Sandile M , Walker, Roderick B
  • Date: 2011
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/184801 , vital:44273 , xlink:href="https://doi.org/10.14227/dt180311p30"
  • Description: The objectives of this study were to compare dissolution profiles of a verapamil (VRP) formulation manufactured inhouse and Isoptin SR using USP Apparatus 2 and 3 and to elucidate drug release kinetics of these dosage forms. Eudragit NE 30D (ethyl acrylate–methyl methacrylate copolymer in a 2:1 ratio) aqueous dispersion was used as a granulating binder for the manufacture of VRP mini-matrix sustained-release tablets. The wet granulation process was performed to prepare free-flowing granules that were blended with Carbopol. The tablets were manufactured using a single-punch press by compression of the granules with magnesium stearate as a lubricant. Drug release was determined in phosphate buffer solution using USP Apparatus 2 and 3. Dissolution data were fitted to zero- and first-order models; in addition, the kinetic data were determined by evaluation of Higuchi release kinetics. The mechanism of drug release was established using the Korsmeyer–Peppas model. In general, all tablets showed high mechanical resistance with less than 1% friability. There was no significant difference between the dissolution profiles of the formulation manufactured in-house and the commercially available product. The release mechanism of the formulated and marketed products was controlled by anomalous non-Fickian diffusion. VRP release was prolonged for 12 h indicating the usefulness of the formulation as a twice-daily dosage form. The mechanism of drug release for the dosage forms was unaffected by the choice of apparatus.
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  • Date Issued: 2011

Dryland conservation areas, indigenous people, livelihoods and natural resource values in South Africa: the case of Kgalagadi Transfrontier Park

  • Authors: Thondhlana, Gladman
  • Date: 2011
  • Subjects: Human ecology -- Kgalagadi Transfrontier Park (Botswana and South Africa) Arid regions biodiversity conservation -- Kgalagadi Transfrontier Park (Botswana and South Africa) Arid regions agriculture -- Kgalagadi Transfrontier Park (Botswana and South Africa) Indigenous peoples -- Ecology -- Kgalagadi Transfrontier Park (Botswana and South Africa) Natural resources conservation areas -- Kgalagadi Transfrontier Park (Botswana and South Africa) Natural resources -- Government policy -- Kgalagadi Transfrontier Park (Botswana and South Africa) Natural resources -- Kgalagadi Transfrontier Park (Botswana and South Africa) -- Management
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4777 , http://hdl.handle.net/10962/d1011732
  • Description: Contemporary conservation and development understanding in both policy and academic circles espouses that natural resources have a significant contribution to the livelihoods of local people and that knowledge of this can better foster conservation policies that are consistent with livelihood and ecological needs. This thesis is based on research conducted in the southern Kalahari region, South Africa among the San and Mier communities bordering Kgalagadi Transfrontier Park. It looks at the importance of natural resources to the San and Mier community groups and ascertains the extent of resource use and its value within broader livelihood portfolios. It also focuses on the cultural values of natural resources and interactions among institutions and actors and how these shape natural resource governance and livelihood outcomes. Overall, natural resources represent an important livelihood source contributing up to 32 % and 9 % of the total income of the San and Mier respectively or up to 46 % and 23 % if livestock incomes are included. However, the dependence on, diversification patterns and distribution of natural resource income vary substantially between and within the two communities. With regards to the cultural values attached to natural resources by the San and Mier, the findings show that these arise from an incredibly diverse and sometimes conflicting array of values that punctuate the two communities’ way of life and they are inextricably linked to resource use. Lastly, governance of natural resources in the co-managed Park and communitymanaged resettlement farms is characterised by complex institutional arrangements, compounded by the existence of multiple actors that have multiple and sometimes conflicting objectives – as shaped by different meanings and interpretations of natural resources. Heightened inter- and intra-community conflicts are common, notably resource use conflicts between the San and Mier and between the San ‘modernist’ and ‘traditionalist’ groups. This demonstrates that the communities’ livelihood dynamics in general and the dependence on natural resources in particular, are closely linked with ecological, economic and social factors including history, culture and present livelihood needs. By exploring the social-environment interactions, the study highlights the complexities and diversity of resource use for livelihoods that should be taken into consideration for both conservation and development policy interventions and research. The main argument of the study is that the contribution of natural resources to local livelihood portfolios in co- and community-managed areas, can be better understood through a consideration of cultural dynamics and institutional arrangements since these condition natural resource access, value and use.
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  • Date Issued: 2011

Dynamics of macrophytes in the East Kleinemonde, a small temporarily open/closed South Afrcan Estuary

  • Authors: Riddin, Taryn
  • Date: 2011
  • Subjects: Estuaries -- South Africa -- East Kleinemonde
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: vital:10605 , http://hdl.handle.net/10948/1529 , Estuaries -- South Africa -- East Kleinemonde
  • Description: The East Kleinemonde Estuary is one of 175 temporarily open/closed estuaries (TOCEs) that represent 70 percent of estuaries in South Africa. TOCEs are small (mostly less than 100 ha), shallow estuaries (average depth < 2 m) that respond quickly to freshwater inflow events. Their connection to the sea can be highly variable resulting in considerable changes in abiotic and biotic conditions. Mouth status depends on a balance between freshwater inflow and marine influence, which in turn affects ambient abiotic conditions. The objective of the study was to identify the abiotic variables which influence macrophyte growth and habitat availability. It was hypothesised that water level and salinity were the two main drivers of macrophyte change and macrophyte habitat would respond very rapidly, in less than a month, when habitat was available. Macrophyte habitats would also have high sediment seed reserves to ensure persistence under highly variable abiotic conditions. Macrophyte cover was monitored monthly in the East Kleinemonde Estuary along three permanent transects. The dominant habitats were submerged macrophytes, intertidal salt marsh, supratidal salt marsh, reeds and sedges. The following abiotic variables; water level, water column salinity, water temperature, Secchi depth, air temperature and rainfall were also measured between March 2006 and January 2010. Time-lag responses of the macrophytes to water level and salinity changes up to four months prior to the sampling session were also assessed. The analysis of a one year dataset highlighted only water level as a driver of change in macrophyte cover, whereas the five year dataset identified salinity as an additional important abiotic driver. This is because during September 2008 to January 2010 a series of large marine overwash events maintained high salinity (> 30 ppt) and high water level (> 1.6 m amsl) in the estuary. Water level increased by up to 0.33 m due to large volumetric changes and salinity was significantly higher in the 16 month closed euhaline phase after the breach (31 ± 0.9 ppt) compared to 21.9 ± 0.9 ppt in the closed polyhaline phase before the September 2008 breach. This increase in salinity significantly reduced the cover of the submerged macrophytes Ruppia cirrhosa and Chara vulgaris. They were replaced by macroalgae during this high salinity phase. The cover of supratidal salt marsh and reed habitats was also significantly reduced during the high water level phase, which in turn would lead to the potential for bank destabilisation and erosion. Based on the average elevation above sea level position of the macrophytes in the East Kleinemonde iv Estuary, a threshold water level was identified as 1.55 amsl. This was taken to be the height above sea level at which there was a maximum cover change for each macrophyte habitat. Above this water level emergent macrophyte habitat would mainly be inundated. This, together with 30 ppt salinity, was identified as the two thresholds for macrophyte change in the East Kleinemonde Estuary. From these thresholds and the 5 year dataset four biotic states were identified as State A: open and tidal, State B: closed with a water level below 1.55 m amsl and salinity between 18 to 30 ppt, State C: closed and water level above 1.55 m amsl and salinity between 18 to 30 ppt and State D: closed and water level above 1.55 m amsl and salinity above 30 ppt. Intertidal salt marsh, reeds and sedges were dominant during the open phase. Submerged macrophytes were dominant during the closed polyhaline state and macroalgae during the closed euhaline state. The high variability of abiotic factors common in TOCEs and the response of macrophyte habitat indicated that macrophytes were resilient to changing states provided they were of relatively short (< 3 months) duration. Macrophytes in the East Kleinemonde Estuary were found to have fast growth rates and large seed reserves in the sediment. The seed banks in the East Kleinemonde, as well as the adjacent temporarily open/closed West Kleinemonde Estuary were quantified for the first time in a South African estuary. The averaged data from both estuaries showed that Charophyte öospores represented almost 72 percent of the sexual propagules in the sediment with a mean öospore density of 31 306 ± 2 293 m-2. This was despite the Charophytes being sparsely located and only representing a maximum of 32.5 percent cover in the above ground vegetation. Historically there must have been stands of Charophytes in the East Kleinemonde Estuary, such that öospores could accumulate to such high density found in this study. The second highest seed density was for the intertidal salt marsh plant Sarcocornia tegetaria (18 percent) (7 929 ± 688 seed m-2), followed by the submerged angiosperm Ruppia cirrhosa (7 percent) (2 852 ± 327 seeds m-2). Although seed density did not differ significantly with sediment depth, seeds still occurred at 20 cm below the surface of the sediment providing a regeneration source in the event of sediment scouring during a flood event. Germination studies in the greenhouse showed that most seeds were viable and Sarcocornia tegetaria began to germinate after 3 days to a maximum of 82 percent after 91 days. Submerged species only germinated after 18 days with a low maximum germination of between 11 and 15 percent. This study has made an original contribution to the field of knowledge on macrophyte responses in a small TOCE as it showed that macrophyte habitats in the East Kleinemonde Estuary have a high natural variability in cover over time, they respond quickly after a disturbance event such as a mouth breach and there are large sediment seed reserves that remain viable from 2 to more than 5 years. This ensures habitat persistence even under unfavourable conditions, such as prolonged periods of mouth closure with high water level and flooding which causes loss of salt marsh species. Given this natural variability it is necessary to predict responses both spatially and temporally in order to manage and maintain ecological functioning in TOCEs. This study identified dominant macrophyte habitat for different abiotic states through the use of water level and salinity thresholds. In the determination of the freshwater requirements of any South African estuary freshwater inflow rates are provided for each estuary's past, present and possible future freshwater inflow scenarios. These flow data are generated by hydrological models and simulated monthly inflow volumes for a period of about 72 years are provided. For the East Kleinemonde freshwater requirement study for any year in that 70-odd year period, the number of high flow and low flow mouth breaches were predicted, as well as the closed state periods. The threshold water level of 1.55 m amsl was also used to filter past, present and future inflow monthly volumes to determine the frequency of the four abiotic states identified in this study. It was based on a water level/water volume equation calculation from a digital elevation model. Results showed that the total closed period in the present state was 83 percent, made up of 48 percent of the time in a polyhaline state (State C) and 35 percent in a euahaline state (State D). A second method was used to quantify available spatial habitat under different water level scenarios. A spatial model was written in Model Builder, an application in ArcGIS that allowed a series of processes to be built. A habitat map was overlaid with a bathymetric map and by selecting water level, available habitat areas were determined and empirical equations of water level versus available habitat were produced. These equations were then used to calculate the available habitat areas for monthly water level conditions from the freshwater requirement study for the past, present and two future inflow scenarios. Using both the threshold water level method and the spatial availability model method it was possible to assess the effect of the two future inflow scenarios on macrophyte habitat vi response. Scenario 1 had a 16 percent reduction in mean annual runoff (MAR) generating low flows for 88.6 percent of the time and a 3.5 percent reduction in flood events. In Scenario 2 there would be a 12 percent reduction in MAR with low flows occurring for 87.5 percent of the year, a 5.3 percent reduction in floods and an 11.5 percent reduction in the open mouth state. The model showed that Scenario 1 would have the highest submerged macrophyte area (12.56 ha versus 12.48 ha in Scenario 2), whereas Scenario 2 produced the largest mudflat and intertidal salt marsh area (7.11 ha versus 7.34 ha) due to lower water level in conjunction with the bathymetry of the estuary. A reduction in freshwater inflow to TOCEs either due to anthropogenic influences or natural precipitation cycles is one of the main threats to the optimum functioning of these estuaries. The results from this study and the two methods of assessing the effect of freshwater inflow scenarios on macrophytes in TOCEs can be integrated into the current freshwater inflow assessment methodology in South Africa, as well as adding to our understanding of the ecological functioning of these small, highly variable estuaries. The methods provide a quick assessment of macrophyte habitat associated with abiotic states under past, present and future inflow scenarios. All that is required to predict macrophyte habitat for different freshwater inflow scenarios (present, past and future) is a habitat map, a bathymetric map and the elevation range of macrophytes in the TOCE being assessed. This, together with the knowledge of response rates, provides invaluable information for the management of TOCEs to maintain their ecological functioning under altered freshwater inflow regimes.
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  • Date Issued: 2011

E-commerce as an alternative marketing channel

  • Authors: Mounsear-Wilson, Clifford
  • Date: 2011
  • Subjects: Electronic commerce -- South Africa -- Eastern Cape , Internet marketing -- South Africa -- Eastern Cape , Electronic commerce -- Technological innovations -- South Africa -- Eastern Cape , Organizational effectiveness -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Masters , MBA
  • Identifier: vital:8605 , http://hdl.handle.net/10948/1615 , Electronic commerce -- South Africa -- Eastern Cape , Internet marketing -- South Africa -- Eastern Cape , Electronic commerce -- Technological innovations -- South Africa -- Eastern Cape , Organizational effectiveness -- South Africa -- Eastern Cape
  • Description: Information technology (IT) has become an integral part of the success and globalisation of business over the last two decades. It is hard to imagine how the efficiencies expected in today’s fast paced business world could possibly be achieved without the advancements in IT. The most significant of these advancements is arguably the advent of the Internet which has empowered businesses of all sizes by giving them the means to promote their products and services at a relatively low cost in markets that would previously have been inaccessible. The aim of this study was to assess whether e-commerce represents an alternative channel for a brick and mortar company wishing to follow a market penetration strategy. The study was based around a company, Canoa Eastern Cape, which trades in the office automation industry in the Eastern and Southern Cape of South Africa. The study investigated the history of Canoa Eastern Cape, focusing predominantly on the growth strategies followed by the business in the past. With a view to the future, growth strategies which could potentially be followed by Canoa Eastern Cape were also investigated. The result of these investigations was a recommendation that Canoa Eastern Cape should follow a market penetration strategy, which will see the business marketing its existing products within its current market by making use of a new distribution channel, more specifically e-commerce. In order to assess the suitability of e-commerce as a tool within a market penetration strategy a literature study was conducted to get a better understanding of ecommerce and its viability as business tool. The literature study focused on eight core concepts felt to be critical in the evaluation of e-commerce, namely: • the development of e-commerce over the past years; • the future of e-commerce; • whether e-commerce is a financial success or not; • requirements for e-commerce to be successful; iv • products that customers are prepared to buy online; • industries most affected by e-commerce; and • demographics of e-commerce users; and • e-commerce in the office automation industry. Using the information gained in the literature study as a basis from which to start, an empirical study was conducted. The objective of the empirical study was to obtain data which would be used to assess the level to which e-commerce has been adopted by consumers in the specific geographic area and whether these consumers are willing and able to make use of e-commerce as an alternative to conventional purchasing for the procurement of office automation consumables and office automation equipment. A quantitative research paradigm was adopted, making use of a structured questionnaire to gather information from the sample of Canoa Eastern Cape’s customers. The data collected from the empirical study were analysed using univariate and bivariate analysis. The findings of the empirical study suggested that: • demographics are a poor indicator of adoption of e-commerce; • there is a significant adoption rate within the sample: o 79.85 percent of the respondents reported to have used e-commerce before for personal use; and o 59.13 percentreported to have used e-commerce before for business use; • there is a high rate of willingness to use e-commerce again: o 91.09 percent of the respondents indicating that they would use e-commerce again for personal use; and o 80.18 percent indicating that they would use e-commerce again for business use; • there is a high likelihood that consumers will buy office automation consumables through an e-commerce channel, with 65.82 percentof the respondents indicating that they would be likely or very likely to buy consumables through an e-commerce channel; • there is no significant difference in the adoption rates between the three main areas within the targeted sample, that is, East London, Port Elizabeth and George and Knysna. Given the findings of the empirical study it is felt that an e-commerce solution does present a viable alternative channel for a brick and mortar company trading in the Office Automation Industry in the Eastern and Southern Cape wishing to follow a market penetration strategy.
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  • Date Issued: 2011

Economic impact studies and methodological bias : the case of the National Arts Festival in South Africa

  • Authors: Bragge, Brent Reuben
  • Date: 2011
  • Subjects: Standard Bank National Arts Festival Standard Bank National Arts Festival -- Economic aspects Performing arts festivals- Economic aspects -- South Africa Arts -- Economic aspects -- South Africa Economic impact analysis Edinburgh International Festival -- Economic aspects Klein Karoo Nasionale Kunstefees (Oudtshoorn, South Africa) -- Economic aspects Volksbladfees (Bloemfontein, South Africa) -- Economic aspects
  • Language: English
  • Type: Thesis , Masters , MEcon
  • Identifier: vital:968 , http://hdl.handle.net/10962/d1002702
  • Description: Over the course of the last three decades, it has become popular practice to evaluate tourism events like cultural festivals in financial terms, through the use of economic impact studies. This can be attributed at least in part to the notable growth in the number of festivals being held globally and, as such, a higher level of competition between festivals for the limited funding which is available. Economic impact studies, and the resultant findings, have thus become powerful tools for the lobbying of sponsorship, and it has become increasingly important that the impact calculations be as accurate as possible, so as to effectively allocate both government and private resources to projects which will be of the greatest benefit to the host region. The allocation of funding is especially vital in an area like the Eastern Cape Province of South Africa, which is faced with many financial difficulties. The allocation of public funds to an event like the National Arts Festival, which is hosted in a relatively wealthy part of the province, might be weighed against initiatives which directly benefit the poorer parts of the region. Although it is acknowledged that the benefits which are felt by the host community of a cultural event go beyond that of the financial, it is often on this basis that festivals are most easily compared. The primary goal of the thesis was to analyse the various forms of methodological bias which can exist in the economic impact analyses (EIA) associated with cultural events. Theoretical considerations were discussed, specifically regarding economic impact as a method of measuring value. Various forms of bias (including data collection, the calculation of visitor numbers, multipliers, defining the area of interest, inclusion of visitor spending, and accounting for benefits only, not costs) are put into a real-life context, through the investigation of economic impact studies conducted on three selected South African festivals (the Volksblad, the Klein Karoo Nasionale Kunstfees, and the National Arts Festival), and one international festival (the Edinburgh Festival). An in-depth comparison of two separate studies conducted at the National Arts Festival (NAF) in 2004 (by Antrobus and Snowball) and 2005 (by Saayman et al.) was made, focussing on the manner in which the economic impact was calculated. Having considered the common forms of bias, and assessing several possible reasons for the difference of approximately twenty million Rand in the advertised economic impacts, it was concluded that, most likely, the miscalculation of visitor numbers was the cause. This was confirmed when the Antrobus and Saayman methods were applied to the 2006 NAF data, and noting that the economic impact figures arrived at were strikingly similar. As such, it is advisable that extreme caution be taken when calculating visitor numbers, as they can significantly influence the outcome of an economic impact study. It is recommended that each study should also have transparent checks in place, regarding the key calculation figures, to ensure that less scrupulous researchers are not as easily able to succumb to the pressure event sponsors might impose to produce inflated impact values.
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  • Date Issued: 2011

Economics of land reform models used in Mashonaland Central Province of Zimbabwe

  • Authors: Musemwa, Lovemore
  • Date: 2011
  • Subjects: Land reform -- Zimbabwe , Agricultural productivity -- Zimbabwe , Land tenure -- Zimbabwe , Infrastructure (Economics) -- Government policy -- Zimbabwe , Land reform beneficiaries -- Zimbabwe , Land use -- Economic aspects -- Zimbabwe , Field crops -- Zimbabwe , Data envelopment analysis -- Zimbabwe , Land settlement -- Zimbabwe
  • Language: English
  • Type: Thesis , Doctoral , PhD (Agricultural Economics)
  • Identifier: vital:11168 , http://hdl.handle.net/10353/435 , Land reform -- Zimbabwe , Agricultural productivity -- Zimbabwe , Land tenure -- Zimbabwe , Infrastructure (Economics) -- Government policy -- Zimbabwe , Land reform beneficiaries -- Zimbabwe , Land use -- Economic aspects -- Zimbabwe , Field crops -- Zimbabwe , Data envelopment analysis -- Zimbabwe , Land settlement -- Zimbabwe
  • Description: The land reform that has unfolded in Zimbabwe since 1980 used different models and had diverse consequences. Since the implementation of the fast tract land reform programme in 2000, Zimbabwe experienced heavy reduction in yield and output at farm level that led to a 70% shortfall in production to meet annual food requirements (Richardson, 2005). The economic crisis in Zimbabwe has been characterized by worsening food insecurity especially in the rural areas where harvests continue to be poor. In the beef sector, Zimbabwe has failed to meet its export quota to the EU. The shortfall in production to meet annual food requirements shows a very grim situation but do not tell us about the performance of resettled farmers who now occupy much of the productive land. The broad objective of the study was to determine and compare the production efficiency of resettled farmers in Zimbabwe across land reform models. In addition, the study determined land use intensity. The study was conducted in the Mashonaland Central Province of Zimbabwe mainly because a wide variety of field crops were grown by resettled farmers. The respondents were stratified into three groups. These were: beneficiaries of land reform before 2000 (resettle scheme), fast track A1 model and fast track A2 model. The three models differ on how they were implemented and supported and this might result in different efficiencies of the models. A total of 245 copies structured questionnaire were administered on the resettled farmers from June to September 2010. Descriptive statistics was applied to the basic characteristics of the sampled households. The effect of model of land reform, gender of the household head, marital status, age of the household head, education, household size, religion, dependence ratio, whether the farmer was fulltime or part-time in farming, experience of the farmers in farming at that environment, total land size owned by the farmers and soil type on revenue per hectare and land use rate were determined using the GLM procedure of SAS (2003). Significance differences between least-square group means were compared using the PDIFF test of SAS (2003). The relationship between Revenue and land utilization was examined using the Pearson‟s correlations analysis. Dependance between response variables that had an effect on either revenue per hectare or land utilization with all the other response variables was tested using the Chi-square test for dependance. To find the effect of arable land used and herd size on revenue per hectare and land use the RSREG Procedure of SAS (2003) was used. Input oriented DEA model under the assumption of constant return to scale was used to estimate efficiency in this study. To identify factors that influence efficiency, a Tobit model censored at zero was selected. The mean land use rate varied significantly (p<0.05) with the land reform model with A2 having highest land use rate of 67%. The A1 and old resettlement households had land use rates of 53% and 46%, respectively. Sex, marital status, age of the household head, education and household size significantly affected land use (P<0.05). Revenue per hectare was not affected by any the factors that were inputted in the model. Results from the DEA approach showed that A2 farmers (large land owners) had an average technical efficiency score of 0.839, while the lowest ranking model (A1) had an average score of 0.618. Small land holders (A1 and the old resettled farmers) are on average less cost-efficient than large land owners, with a score of 0.29 for the former compared with 0.45 for the latter. From the factors that were entered in the Tobit model, age of household head, excellent production knowledge and farmer status affected technical efficiency whereas allocative efficiency was only affected by good production knowledge, farm size, arable land owned and area under cultivation. Factors which affected economic efficiency of the resettled farmers are secondary education, household size, farm size, cultivated area and arable land owned. None of the included socio-economic variables has significant effects on the allocative and economic efficiency of the resettled farmers. Thus, the allocative and economic inefficiencies of the farmers might be accounted for by other natural and environmental factors which were not captured in the model.
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  • Date Issued: 2011

Ecotherapy in post-conflict healing: a study of the experiences of ex-combatants in the Eastern Cape township of Mdantsane

  • Authors: Mbona, Sifingo
  • Date: 2011
  • Subjects: Post-traumatic stress disorder , Veterans -- Services for , Human services -- South Africa -- Eastern Cape , Environmental psychology
  • Language: English
  • Type: Thesis , Masters , M SW
  • Identifier: vital:11758 , http://hdl.handle.net/10353/331 , Post-traumatic stress disorder , Veterans -- Services for , Human services -- South Africa -- Eastern Cape , Environmental psychology
  • Description: During this research project, an attempt was made to understand the role of ecotherapy as a therapeutic model in post conflict healing. The aim was to evaluate the application and significance of ecotherapy as an intervention strategy for post conflict healing for individuals who were exposed to violent encounters during the liberation struggle. Eight respondents (involved in the arms struggle) from Mdanstane Township in the Eastern Cape, were taken through a series of workshops as part of an ecotherapy healing process. The research concluded that all the participants had suffered from some form of traumatic stress because of their exposure to violence and violent experiences. Moreover, on closer examination the situation of ex-combatants proved to be more complex and often volatile, due to the absence of social support, loss of social status, absence of economic, employment opportunities, and the dislocation from their families and communities. Subsequent to the ecotherapy intervention, a positive outlook amongst the participants was recorded. Furthermore, there was an indication of a significant increase in their sense of self-worth and personal development, which influenced the manner in which the participants viewed the world, related to their families or communities and responded to life in general. Essentially, the research findings, conclusions, and recommendations contributed towards a better understanding of ex-combatants and the value that could be derived from ecotherapy as a post conflict healing method for individuals and groups exposed to violence and trauma.
  • Full Text:
  • Date Issued: 2011

Educating users about information security by means of game play

  • Authors: Monk, Thomas Philippus
  • Date: 2011
  • Subjects: Computer security , Educational games -- Design , Computer networks -- Security measures
  • Language: English
  • Type: Thesis , Masters , MTech
  • Identifier: vital:9748 , http://hdl.handle.net/10948/1493 , Computer security , Educational games -- Design , Computer networks -- Security measures
  • Description: Information is necessary for any business to function. However, if one does not manage one’s information assets properly then one’s business is likely to be at risk. By implementing Information Security controls, procedures, and/or safeguards one can secure information assets against risks. The risks of an organisation can be mitigated if employees implement safety measures. However, employees are often unable to work securely due to a lack of knowledge. This dissertation evaluates the premise that a computer game could be used to educate employees about Information Security. A game was developed with the aim of educating employees in this regard. If people were motivated to play the game, without external motivation from an organisation, then people would also, indirectly, be motivated to learn about Information Security. Therefore, a secondary aim of this game was to be self-motivating. An experiment was conducted in order to test whether or not these aims were met. The experiment was conducted on a play test group and a control group. The play test group played the game before completing a questionnaire that tested the information security knowledge of participants, while the control group simply completed the questionnaire. The two groups’ answers were compared in order to obtain results. This dissertation discusses the research design of the experiment and also provides an analysis of the results. The game design will be discussed which provides guidelines for future game designers to follow. The experiment indicated that the game is motivational, but perhaps not educational enough. However, the results suggest that a computer game can still be used to teach users about Information Security. Factors that involved consequence and repetition contributed towards the educational value of the game, whilst competitiveness and rewards contributed to the motivational aspect of the game.
  • Full Text:
  • Date Issued: 2011

Effect of alkaline pre-treatments on the synergistic enzymatic hydrolysis of sugarcane (Saccharum officinarum) bagasse by Clostridium cellulovorans XynA, ManA and ArfA

  • Authors: Beukes, Natasha
  • Date: 2011
  • Subjects: Sugarcane -- Biotechnology Lignocellulose -- Biotechnology Renewable energy sources Hydrolysis Enzymes
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:3952 , http://hdl.handle.net/10962/d1004011
  • Description: The continual increase in industrialization and global population has increased the dependency and demand on traditional fossil fuels for energy; however, there are limited amounts of fossil fuels available. The slow depletion of fossil fuels has sparked a fresh interest in renewable sources such as lignocellulose to produce a variety of biofuels, such as biogases (e.g. methane), bioethanol, biodiesel and a variety of other solvents and economically valuable by-products. Agricultural crop wastes produced in surplus are typically lignocellulosic in composition and thus partially recalcitrant to enzymatic degradation. The recalcitrant nature of plant biomass and the inability to obtain complete enzymatic hydrolysis has led to the establishment of various pre-treatment strategies. Alkaline pre-treatments increase the accessibility of the exposed surface to enzymatic hydrolysis through the removal of acetyl and uronic acid substituents on hemicellulose. Unlike the use of steam and acid pre-treatments, alkaline pre-treatments solubilize lignin and a small percentage of the hemicellulose, increasing enzyme accessibility and thus the hydrolysis of lignocellulose. The majority of Clostridium cellulovorans associated enzyme synergy studies have been devoted to an understanding of the cellulolytic and hemi-cellulolytic degradation of plant cell walls. However, little is known about the effect of various physical and chemical pre-treatments on the synergistic enzymatic degradation of plant biomass and possible depolymerization of plant cell walls. This study investigates the use of slake lime, sodium hydroxide and ammonium hydroxide to pre-treat sugarcane bagasse under mild conditions and elucidates potentially important synergistic associations between the C. cellulovorans enzymes for the enhanced degradation of lignocellulose. The primary aims of the study were addressed using of a variety of techniques. This included suitable vector constructs for the expression and purification of recombinant C. cellulovorans enzymes, identification of the effects of various pre-treatments on enzyme synergy, and identification of the resultant reducing sugars and phenolic compounds (released during the pre-treatment of the bagasse). This study also made use of physical and chemical pre-treatment methods, protein purification using affinity, high performance liquid and thin layer chromatography, mass spectrometry, sodium dodecyl sulphate and fluorophore-assisted polyacrylamide gel electrophoresis (FACE) , enzymatic degradation and synergy studies with various substrates indirectly using the 3, 4-dinitrosalicylic acid (DNS) reducing sugar assay. From this investigation, the following conclusions were made: alkaline pre-treatment successfully solublised, redistributed and removed lignin from the bagasse, increasing the digestibility of the substrates. In summary, the most effective pre-treatment employed 0.114 M ammonium hydroxide / gram bagasse at 70°C for 36 hours, followed by hydrolysis with an enzyme cocktail containing 25% ManA and 75% XynA. This increased the production of sugars approximately 13-fold. Analysis of the sugars produced by the synergistic hydrolysis of sugarcane bagasse (SCB) indicated the presence of xylose, indicating that the enzymes are potentially bifunctional under certain conditions. This study indicated that the use of mild pre-treatment conditions sufficiently removed a large portion of lignin without affecting the hemicellulose moiety of the SCB. This facilitated the potential use of the hemicellulose component for the production of valuable products (e.g. xylitol) in addition to the production of bioethanol. Thus, the potential use of additional components of holocellulose may generate an additional biotechnological benefit and allow a certain degree of flexibility in the biofuel industry, depending on consumer and industrial needs.
  • Full Text:
  • Date Issued: 2011
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