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The effect of restricted environments on selected postural, physiological and perceptual responses

  • Authors: Wolfe, Amy
  • Date: 2008
  • Subjects: Human engineering , Posture , Human mechanics , Work environment , Human beings -- Effect of environment on , Musculoskeletal system -- Wounds and injuries , Industrial safety , Work -- Physiological aspects , Stress (Physiology)
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5115 , http://hdl.handle.net/10962/d1005193 , Human engineering , Posture , Human mechanics , Work environment , Human beings -- Effect of environment on , Musculoskeletal system -- Wounds and injuries , Industrial safety , Work -- Physiological aspects , Stress (Physiology)
  • Description: Manual lifting tasks are the predominant means of transporting materials in industry with many of these tasks being performed in confined spaces. Research has tended to focus on the biomechanical implications of working in small spaces with a decided lack of information about the physiological and perceptual responses in these environments. This holistic study therefore investigated the manner in which the human operator responded to conditions where the ceiling height was lowered and reach demands increased. Thirty-two young physically active male subjects (age: 21.55yr; stature: 1810mm) were recruited to complete a 2-way repeated measures experiment during which four lifting protocols where different combinations of ceiling height (‘normal’ or reduced to 1460mm in height) and reach demands (400mm or 800mm) were tested. A crude postural analysis was conducted while physiological responses were detailed and continuously monitored. Perceptual responses were also assessed. The tasks with a ‘normal’ ceiling height (mean compression forces: 2615N; mean shearing forces: 388N) and the greatest reach distance (mean compression forces: 3655N; mean shearing forces: 386N) placed individuals under the highest strain. Mean heart rate (HR) responses were significantly lower (p < 0.05) in the URN condition when compared to the RF condition. Furthermore, HR responses were statistically significantly affected by the height of the ceiling and the reach depth. Statistically significant differences (p< 0.05) in mean tidal volume (VT) occurred in the least (URN) and most (RF) restrictive conditions. Statistically significant differences (p < 0.05) in mean VE were evident between URN and URF, between URN and RF and between RN and RF. Ceiling height and reach demands had a statistically significant effect on all respiratory responses. There was a statistically significant difference in mean oxygen consumption (VO2) between the URN and all other conditions, and between the most restricted task (RF) and all other conditions. Both the effect of ceiling height and reach demands had a statistically statistically significant impact on VO2. Respiratory quotient (RQ) was significantly higher when loads were moved over 800mm compared to 400mm yet ceiling height did not have a statistically significant effect on RQ. Mean energy expenditure was significantly higher in the RF condition compared to the two least restrictive conditions (URN and RN). Statistically significant differences in EE were also evident between URN and RN, and between URN and URF. EE was significantly affected by reductions in ceiling height and increases in reach demands. Perceptually, the RF task (mean ‘Central’ RPE of 11) was perceived to place significantly greater cardiorespiratory demands on the operator compared to the URN (CRPE: 10) and RN (CRPE: 10) conditions. Statistically significant differences in perceived musculoskeletal strain only occurred between URN and RF. The effect of reach was perceived to have a statistically significant effect on both cardiovascular and musculoskeletal demands whereas ceiling height only had a statistically significant effect on musculoskeletal demands. The greatest discomfort was experienced in the lower back with the most intense discomfort occurring in the RN condition.
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  • Date Issued: 2008

Exploring employee morale at the Port Elizabeth plant of Cadbury (South Africa)

  • Authors: Wolfaardt, Michelle
  • Date: 2006
  • Subjects: Cadbury Ltd , Chocolate industry -- South Africa -- Port Elizabeth , Employee morale , Job satisfaction , Performance standards , Employees -- Rating of , Personnel management
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:3093 , http://hdl.handle.net/10962/d1003129 , Cadbury Ltd , Chocolate industry -- South Africa -- Port Elizabeth , Employee morale , Job satisfaction , Performance standards , Employees -- Rating of , Personnel management
  • Description: In the current business climate, performance is increasingly determined by how flexibly and effectively companies can utilize their human resources and this in tum, is influenced by employee morale. Morale refers to a state of psychosomatic health marked by an energetic, decisive resolution to achieve a given goal. When morale is low, employees may do what is required but do not have the energy to 'go the extra mile'. The importance of maintaining high morale is thus evident. The following project involved a study of morale in Cadbury's Port Elizabeth plant. Cadbury management was concerned about low morale following a recent merger with Bromor Foods. They thus wanted to assess: the state of current morale; any factors that may be influencing it; indicators of low morale (so that it may be monitored in the future) and finally, ways of addressing any existing morale issues. In order to achieve these aims, the researcher conducted interviews with various people to explore morale issues from employees' perspectives. She then sought confirmation for these views at the organizational level through the use of a survey. Statistical and thematic analyses showed morale to be low for middle managers and revealed a variety of indicators and influencing factors, as well as suggestions for addressing them. Despite the need to boost the sample size with convenience sampling, and thus, reduced representivity, the research was successful in answering the research aims.
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  • Date Issued: 2006

Some aspects of the Franco-German economic relations between the two world wars

  • Authors: Wolf, Hans J
  • Date: 1970
  • Subjects: Economic history -- 1918-1945 , France -- Economic conditions -- 20th century , Germany -- Economic conditions -- 20th century , France -- Foreign relations -- Germany , Germany -- Foreign relations -- France
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:1067 , http://hdl.handle.net/10962/d1007687
  • Description: From Preface: In this thesis I have aimed at covering a field in Economic History where not many suitable publications are available in English. During the interwar period, the maintenance of peace and harmonious international relations was directly dependent on a reconciliation of the conflicting interests between France and Germany. In studying the economic implications of the Franco-German antagonism, I have tried to throw light upon the crucial role which this relationship played. The Appendix offers a quantitative survey of economic conditions in the two countries and of the relevant production and exchange problems. To assist the reader who is not completely familiar with this period, a brief summary of the relevant conferences, agreements and treaties is also offered in the Appendix, as well as some short biographical notes. I would like to make it clear, however, that this thesis is neither supposed to be a paraphrase of the Appendix, nor a mere treatise on the commercial relations between the two countries concerned. I aimed rather at revealing the forces behind the events and at illustrating how economic problems became quite often subject to political and military considerations. When trying to attain some understanding of Franco-German relations, it seems advisable to look not only at the interbellum period, but in the first instance to become aware of the currents of history which finally led to the two disastrous World Wars.
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  • Date Issued: 1970

Regulating franchise operations in South Africa : a study of the existing legal framework with suggestions for reform.

  • Authors: Woker, Tanya Ann
  • Date: 2009
  • Subjects: Franchise Association of Southern Africa , Franchises (Retail trade) -- Law and legislation -- South Africa , South Africa. Dept. of Trade and Industry , Common law -- South Africa , Commercial law -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:3721 , http://hdl.handle.net/10962/d1015719
  • Description: This thesis analyses the existing legal framework that applies to franchising in South Africa today. The study begins with an examination of the history and nature of the franchise contract, focusing particularly on the nature of the franchise relationship. This study is undertaken in order to substantiate the argument that franchising is a unique method of doing business. There is a need therefore to recognise that the franchise contract is a special contract in its own right, just like contracts of sale, lease, insurance and suretyship. The study then goes on to examine the problems which are experienced in the sector, as well as the law which must provide solutions to these problems. The research will show that in a modern commercial world the existing legal framework, especially the common law, cannot adequately deal with many of these problems. The complex relationship between franchising and competition law is also explored. A common thread that emerges from franchise disputes is the lack of protection afforded to the interests of franchisees. Franchisees tend to be at the mercy of economically stronger franchisors, hence the belief that there is a need for a stronger regulatory framework. The study then shifts to proposals for reform. In 2000 the Department of Trade and Industry (DTI) established the Franchise Steering Committee in conjunction with the Franchise Association of South Africa (FASA) to review the regulatory environment. This Committee drafted franchise legislation which aimed to bring the regulation of the sector under the control of the DTI. This legislation has not been implemented and the DTI has changed its strategy. Instead of dealing with franchising independently, franchising will fall within the scope of consumer protection legislation. Both the consumer protection legislation and the legislation proposed by the Franchise Steering Committee are thoroughly examined and explained. Shortcomings in the proposals are highlighted and an alternative approach is recommended. It is proposed that franchise-specific legislation should be introduced but that this legislation should establish a system of co-regulation between the government and the franchise sector.
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  • Date Issued: 2009

A cognitive behavioural treatment program for chronic lower back pain: a case study approach

  • Authors: Wohlman, Michael Avron
  • Date: 2000
  • Subjects: Backache -- Psychological aspects , Backache -- Treatment , Backache -- Treatment -- Case studies
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:3087 , http://hdl.handle.net/10962/d1002596 , Backache -- Psychological aspects , Backache -- Treatment , Backache -- Treatment -- Case studies
  • Description: A cognitive behavioural treatment program for chronic lower back pain was designed, implemented and evaluated. The outpatient treatment program included education sessions, goal setting, graded activity training, physical exercise, relaxation training, cognitive techniques, social skills training, and medication reduction. Three participants volunteered to participate in the eightweek treatment program. Of the three participants, only one completed the program successfully. The results were used to critically discuss and evaluate the literature. The successful participant showed significant improvement in activity levels, decrease in subjective levels of pain, as well as decreased levels of anxiety and depression. It was shown that correcting cognitive distortions (e.g. selective abstraction, catastrophising, misattribution) and challenging early maladaptive schemas of abandonment, emotional deprivation and emotional inhibition (Young, 1990) assisted in enhancing coping mechanisms and the belief that the pain episodes would be short-lived and could be controlled. There was considerable improvement for the second participant, although he chose to withdraw from the program prior to its completion. The components of the psycho-education, relaxation and stress management and exercise program were beneficial for him. The third participant failed to accept the treatment formulation, and did not engage collaboratively in the treatment program. The case is presented as a point for examining therapeutic ailures.
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  • Date Issued: 2000

Radio observation of the Gum Nebula Region

  • Authors: Woermann, Beate
  • Date: 1997
  • Subjects: Radio sources (Astronomy) Nebulae -- Observations Radio astronomy
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5485 , http://hdl.handle.net/10962/d1005271
  • Description: This thesis describes the results of an investigation of the physical properties of the Gum Nebula. For this investigation a radio continuum map of the region was made at 2326 MHz and resolution ⅓° with the HartRAO antenna. This map was used to generate spectral index images and an infrared to radio flux density ratio (IRR) image. The latter image shows that the IRR of the nebula is in the range 20 to 250, identifying it as an old SNR. Several spectral index images of this region were generated using two different methods, one based on the isolation of the nebula from its background radiation, the other based on TT-plots (Turtle et al., 1962). The two methods yield similar results, which show that the nebula has a thermal shell with a non-thermal region in its interior. Below the galactic plane the thermal region dominates and above the plane the nonthermal region. These results suggest a model of an old SNR with an H II region shell. Spectral line observations of hydrogen recombination lines and hydroxyl (OH) were made with the HartRAO and the Mopra telescopes. The detection of hydrogen recombination lines at four positions in the thermal regions of the nebula give electron temperatures and emission measures in the ranges 4000 to 6000 K and 220 to 460 pc.cm⁻⁶ respectively. The turbulent velocities are of the order of 20 km/s. A search for shocked OH lines at 1667 MHz and 1720 MHz in the Gum Nebula gave results that were negative, but numerous unshocked 1667 MHz OH lines were detected. The latter were used in a test for an expansion of the nebula. The most plausible fit to the data gives an expansion centre at l = 260.5°, b = -2.5° and at a distance of 0.7 kpc from us. The front face angular radius and expansion velocity are 10.5° and 16 km/s respectively. The back face angular radius and expansion velocity are 8.50 and 7 km/s respectively.
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  • Date Issued: 1997

Abalone stock enhancement at Cape Recife, Eastern Cape Province of South Africa

  • Authors: Witte, Warren
  • Date: 2017
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/45695 , vital:25532
  • Description: The potential for restocking depleted natural reefs with hatchery abalone, Haliotis midae, to support a commercial ranching venture in the Eastern Cape Province of South Africa was investigated. A baseline stock assessment and analysis of historical fishery data provided compelling evidence of significant declines in the abalone stock, attributed to uncontrolled illegal fishing over the last 20 years at the study site. A ranching pilot study was undertaken where small-scale replicated seeding experiments were set up which quantified the effect of seed size, density and habitat on survival and growth of hatchery-reared abalone. Thirty-six experimental plots were seeded with 8400 abalone spread evenly over two broad habitats. Mean retrievals of seeded abalone were 17% ranging from 4 - 42% after a minimum of eight months at large. Release density and large-scale habitat had no significant effect on seed survival, but smaller seed size (40.0 ±3.7mm shell length) achieved higher (F1, 22 = 4.64, p = 0.042) retrievals than larger seed size (53 ±3.7mm). Growth rates were an average of 30% higher in the shallow sites compared deeper sites (t1, 1091 = -2.79, p = 0.005). There was seasonal component in growth with a 0.55 ± 0.04 mm per month higher rate in summer than during winter (t1, 1091 = -12.45, p < 0.001). Abalone seed releases were also conducted on a larger scale, which focused on the economic potential for commercial-scale ranching. Over 160 sites were seeded with 1.4 million hatchery reared abalone or 30 metric tonnes. Seventeen sites underwent long-term monitoring of survival with repeated sampling events on sites over a period of up to 666 days. Nine of these sites were seeded with 140800 small abalone (29 – 40 mm), three sites with 25100 medium abalone (30 – 46 mm) and five sites with 14700 large abalone (60 – 84 mm). There was a significant difference in survival between the seed sizes (F4,6329 = 304.3, P < 0.001). The Generalized Linear Mixed Model (GLMM) calculation estimated the instantaneous apparent mortality rate for small, medium and large abalone at 1.19 yr-1 , -0.9 yr-1 and -0.67 yr-1 , which equated to a survival rate of 21%, 28% and 36% per year respectively. The weighted mortality rate calculated according to the seed size differential mortality and the number of seed released for those sizes was 1 yr-1 or 25% survival. In conjunction with a conservative somatic growth rate of 1.2mm.m-1 and plausible emigration rates, a range of biomass harvesting estimates were obtained. Movement and mortality were investigated using video analysis which showed that hatchery seed had the ability to move considerably once released onto natural reefs and confirmed that mortality immediately following releases was due to the heavy predation pressure as confirmed by shell collections. This project has demonstrated that potential exists for ranching in South Africa and highlights critical factors that need to be addressed if ranching is to be an economically viable operation.
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  • Date Issued: 2017

Formulation development, manufacture and evaluation of a lamivudine-zidovudine nano co-crystal thermo-responsive suspension

  • Authors: Witika, Bwalya Angel
  • Date: 2020
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/140546 , vital:37897 , http://dx.doi.org/10.21504/10962/140546
  • Description: Expected release date-April 2021
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  • Date Issued: 2020

The development, manufacture and characterisation of niosomes intended to deliver nevirapine to the brain

  • Authors: Witika, Bwalya Angel
  • Date: 2017
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/65257 , vital:28715
  • Description: Expected release date-May 2019
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  • Date Issued: 2017

The role of Facebook in a survivor’s post-assault life: rape on campuses, women activists, and mental health

  • Authors: Witi, Sinethemba Juliet
  • Date: 2022-10-14
  • Subjects: Online social networks , Rape in universities and colleges South Africa Makhanda , Student movements South Africa Makhanda , College students Mental health South Africa Makhanda , Sex crimes South Africa Makhanda , Social media and college students South Africa Makhanda , Intersectionality (Sociology) , Womanism
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/405952 , vital:70222
  • Description: The rise of Social Networking Sites (SNSs) has raised concerns about the negative impact social media platforms, and in particular Facebook, has on their users. Research has linked the excessive use of Facebook with mental health challenges such as loneliness, depression, and stress. This research examined how Yolanda Dyantyi, a gender rights activist registered as a student from 2015 to 2017 at Rhodes University, used Facebook as an outlet following the #RUreferencelist protests and her subsequent permanent exclusion from the institution for her role in the protests. The study explored Dyanti’s use of Facebook, examining in particular her ongoing activism, her mental health challenges, and her struggles to re-establish herself in a community after the exclusion from Rhodes. The study employed an intersectional feminist theoretical framework and drew on a qualitative content analysis, a semi-structured interview, and the scroll back method to review the Facebook posts she had made. A thematic analysis of the data showed that Dyantyi is a multifaceted, and evolving Facebook user and contrary to existing research her prolific use of Facebook has had positive effects on her mental health and has enabled her to build social capital. The study suggests that activism is an important component to research alongside studies of mental health on such media platforms. , Thesis (MA) -- Faculty of Humanities, School of Journalism and Media Studies, 2022
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  • Date Issued: 2022-10-14

A study of the rabbit eye test system to determine the activity of acidic non-steroidal anti-inflammatory agents

  • Authors: Wiseman, Ian Charles
  • Date: 1977
  • Subjects: Nonsteroidal anti-inflammatory agents , Anti-inflammatory agents
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:3855 , http://hdl.handle.net/10962/d1013276
  • Description: From introduction : "Inflammation per se, has been defined sufficiently to permit a rational approach to the search for drugs that modify this process, but satisfactory animal models for most rheumatoid diseases are not available". (Swingle 1974) In the search for new meaningful procedures for the detection and evaluation of anti-inflammatory drugs, the rabbit eye as a test system was studied.
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  • Date Issued: 1977

The British organ and its music during the nineteenth century

  • Authors: Wise, James Patrick Gerald
  • Date: 1957
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:2694 , http://hdl.handle.net/10962/d1013429
  • Description: It is a curious fact that, although the literature of the organ is a reasonably large one, no attempt has been made to study the history of the instrument in Britain in any detail. Hopkins and Rimbault covered a certain amount of ground up to 1800, but even they could not deal very extensively with the subject in a volume that was tracing the history of the organ not only in Britain, but throughout Europe, and not only its history but its construction also. For similar reasons Dr. Sumner? (name unclear), in his recent book, could paint little more than an outline picture. However, the British organ's development prior to 1800 was one that does not admit of very discursive treatment. Progress was lamentably slow in comparison with that of Continental organs; and consequently the nineteenth century dawned with British organ-building literally hundreds of years behind that of France, Germany, Belgium and Holland. Yet, a century later, the position was redeemed, and even before the present era opened, the products of British organ-builders were not merely equal to, but, in general superior to those of the Continent in tonal design, mechanism, in artistic finish, and in ordinary maintenance and preservation. The nineteenth century, then, must clearly be regarded as a remarkable, indeed glorious, period in British organ-building, in fact one is tempted to enquire, whether there exists, in the entire artistic and scientific history of any country a similar example of accelerated development; in which one country has made up three hundred years' leeway in one third of that time. This thesis therefore, sets out to examine and describe the events of the century, and the men who were responsible for those events, to trace the growth of the organ in its various departments, and as the instrument itself is only a means to an end, to say something about the way in which it was used, the music that was played on it, and the men who played and composed this music. The thesis is divided into two volumes, the first deals entirely with the history of the instrument and its builders during the nineteenth century, with an introduction briefly recounting the story from the Restoration up to the year 1800; and the second volume is concerned with the music and the musicians as well as the several detailed indexes which are so necessary if a work of this kind is to be of any value at all. A full bibliography is given in Volume Two, but supreme acknowledgement must be paid here to the quarterly periodical "The Organ" - still thriving after an active career that began in July 1921. Its scholarly articles range over the whole field of international organ-building and organ-history, and without its help this thesis would have been far less comprehensive in its scope and far lesss authorative in its source-material.
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  • Date Issued: 1957

Microemulsions : a new perspective in the treatment of paediatric and geriatric tuberculosis patients

  • Authors: Wisch, Michael Henry
  • Date: 2000
  • Subjects: Emulsions (Pharmacy) , Tuberculosis -- Treatment -- South Africa , Tuberculosis in children -- Treatment , Tuberculosis in old age -- Treatment , Tuberculosis -- Treatment
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:3805 , http://hdl.handle.net/10962/d1003283 , Emulsions (Pharmacy) , Tuberculosis -- Treatment -- South Africa , Tuberculosis in children -- Treatment , Tuberculosis in old age -- Treatment , Tuberculosis -- Treatment
  • Description: Tuberculosis(TB) was declared to be a global emergency in 1993, with South Africa declaring it to be the country’s top health priority in 1996, but ineffective treatment strategies have led to fewer than half of all treated patients in South Africa being cured. At present,paediatric treatment remains a problem, as the antitubercular preparations of rifampicin, isoniazid and pyrazinamide, that are currently available, were not initially designed for the treatment of paediatric TB patients, providing a motivation for this project. The aim of this project is thus the development of a microemulsion dosage form for the oral delivery of RIF(Rifampicin), INH(Isoniazid) and PZA(Pyrazinamide) in combination. RIF, INH and PZA were adequately characterised with reference to the monograph standards referenced and were found to be sufficiently pure to be used in subsequent work. A chromatographic system and conditions were selected and validated as being optimal for HPLC analysis of RIF, INH and PZA in combination, with a drug partitioning method for miglyol 812 developed and validated. Ternary and pseudo-ternary phase diagrams were constructed and reported, all employing miglyol 812 as the lipid. It was undoubtedly the imwitor 308 and crillet 3 combination o/w microemulsion system that proved most successful, maintaining homogeneity on dilution. The microemulsion used in formulation comprised imwitor 308 (27.63%), crillet 3 (27.63%), miglyol 812 23.68%) and water (21.06%). The stability of RIF, INH and PZA was investigated in aqueous solution, miglyol 812, corn oil, 10%m/v cremophor RH, 5%m/v imwitor 308, 10%m/v crillet 3 and 70%m/v sorbitol solution. Trends in the stability assessments conducted on RIF, INH and PZA were noted, with slight variation depending on the formulation component being evaluated. RIF invariably demonstrated temperature and oxidation dependent degradation in all vehicles, with a definite distinction possible between samples stored at 25, 40 and 600C over a 7 day trial period. A definite advantage of storing RIF solutions under nitrogen was observed, with these solutions showing less degradation over the course of the trial, than those stored under air. INH produced a pronounced increase in the degree of degradation of RIF, whereas PZA had a negligible effect on it’s stability. INH proved to be most stable in the 70%m/v sorbitol solution with no significant oxidation or temperature dependent degradation indicated. Temperature dependent degradation was only noticable when INH was in combination with RIF, most significant in crillet 3 solution. PZA was the most stable of the three drugs, remaining relatively unaffected by temperature and the presence of air, independent of the vehicle employed, although the drug remaining did decrease slightly in the presence of RIF.Due to drug dose specifications and solubility limitations, the final formulation assessed, only contained RIF and INH, despite INH and PZA having no significant effect on the stability of each other. The solubility of PZA in the lipid and aqueous components of the microemulsion was not great enough to achieve the required 500 mg/10ml dose, while RIF and INH could achieve the respective 150mg/10ml and 100mg/10ml dose. RIF stability was improved, as anticipated, with the incorporation of RIF into the internal phase decreasing contact with INH which has been shown to affect it’s stability. RIF behaved as predicted, possessing greater stability than shown in the individual formulation components, however, INH did not, being less stable in formulation in the absence of antioxidant, than in it’s presence. A novel microemulsion formulation capable of delivering the incompatible RIF and INH in combination, with numerous microemulsion systems mapped,with the ability of being used for the delivery of other lipophilic drugs and drug combinations, was produced.The final formulation provided valuable information into possible future improvements of the microemulsion to improve drug stability.
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  • Date Issued: 2000

Synthetic approaches to marine labdane diterpenes

  • Authors: Wisch, Gregory Albert
  • Date: 2002 , 2013-05-10
  • Subjects: Diterpenes
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4289 , http://hdl.handle.net/10962/d1003131 , Diterpenes
  • Description: The work presented in this thesis describes the synthesis of labd-13-en-8ß, 15-diol (46) a stable reduced derivative of an unstable marine natural product aldehyde [8ß-hydroxylabd-13E-en-15-al (6)] isolated by Cimino, et al. from the skin of a Notaspidean mollusc Pleurobranchaea meckelii. The rationale for the synthesis was to provide sufficient 46 for eventual mild oxidation to 6 and investigation of the biological activity of this latter compound. (-)-Sclareol (32), a common diterpene synthetic precursor, was the starting point for the ten step synthesis of 46 described in this thesis. A search of the literature revealed that only one non stereospecific synthesis of 46 had been previously reported. To provide the necessary background to the synthetic component of this thesis, both the occurrence of labdane and ent-labdane in the marine environment and the use of sclareol in the synthesis of marine natural products, was reviewed. The initial step in the synthesis of 46 was the potassium permanganate oxidation of sclareol to give a bisnorlabdane ketone. Reduction of this ketone with lithium aluminium hydride produced a mixture of diols which, through t-butyldimethysilyl triflate protection, afforded a quantitative route to protecting the C-13 ketone in an effort to prevent unwanted intramolecular cyclization reactions. Dehydration of the tertiary alcohol moiety at C-8 with phosphorous oxychloride yielded the Δ⁸·¹⁵ exocyclic alkene required for the next oxidation step. Ozonolysis succeeded in producing the desired C-8 ketone after much deliberation and research into alternative oxidation strategies. Methyl lithium methylation quantitatively afforded the desired a-methyl substitution at C-8, identified at the onset as the key step in the synthesis. Tetra-butylarnmonium fluoride deprotection yielded the 8ß,13-dihydoxylated product, which was in turn subjected to a Swern oxidition to give the desired 8ß-hydroxy-bisnorlabda-13-one. A modified Horner-Wadsworth-Emmons reaction allowed for elaboration at C-13 to yield a to Δ¹³ olefin with a terminal C-15 ethyl ester. Diisobutylaluminium hydride reduction of the ester produced the desired labd-13-en-8ß, 15-diol (46) in a low overall yield of 3.4%. Although opportunities for optimization of at least three steps in the synthesis exist, time constraints prevented both optimization of these steps and an investigation of the oxidation of 46 to 6. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
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  • Date Issued: 2002

The teaching of ecology in schools: a literature review

  • Authors: Wiredu, Christopher Agyei
  • Date: 2002
  • Subjects: Environmental education Teachers -- In-service training -- South Africa Science -- Study and teaching -- South Africa Ecology -- Study and teaching
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1413 , http://hdl.handle.net/10962/d1003134
  • Description: Project 1: This is a literature review on the teaching of ecology in South African schools. The importance of ecology education in the school curriculum is well reported. It is also reported that in spite of the apparent importance of the subject, not much ecology is taught or learned in schools. This report examines what ecology is supposed to be about and the challenges that confront its teaching. The approaches to teaching the subject are also discussed. It would seem that if teachers focus on teaching ecological concepts using constructivist teaching/learning strategies, students might be helped to learn ecology meaningfully. Project 2: 'Constructing eco-concepts' is a case study that reports the effects of a module whose design was informed by social constructivist ideas on the understanding of selected ecological concepts by college students. Social constructivism as a philosophy of learning has gained increasing attention in science education in recent times and yet the approach is so alien to so many. Many teachers still teach by the traditional teacher-centred approaches. This research project reports the conceptual change of students after undertaking the module. It also reports the students' perceptions about the teaching/learning strategies employed in the module. It would seem that the social constructivist strategies used in the module assisted the students to improve their frameworks of ecological concepts. Data also tend to reveal that the students enjoyed the approach to learning and had positive views about the social constructivist teaching/learning approach. Project 3: With the advent of the new curriculum framework for South Africa, the outcomes based curriculum, it would seem that teachers could no longer approach teaching by the traditional transmission methods. Colleges of education have been criticised for producing teachers who do not seem to be adequately prepared for their job. Presently, the argument seems to be that teachers would need in-service education on a wide scale and the colleges of education would seem to be important in-service teacher education centres. This research, using case study methodology, investigated the potential of one of the colleges of education to become an in-service teacher education institution based on its physical and human resources.
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  • Date Issued: 2002

Implementing non-photorealistic rendering enhancements with real-time performance

  • Authors: Winnemöller, Holger
  • Date: 2002 , 2013-05-09
  • Subjects: Computer animation , Computer graphics , Real-time data processing
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4580 , http://hdl.handle.net/10962/d1003135 , Computer animation , Computer graphics , Real-time data processing
  • Description: We describe quality and performance enhancements, which work in real-time, to all well-known Non-photorealistic (NPR) rendering styles for use in an interactive context. These include Comic rendering, Sketch rendering, Hatching and Painterly rendering, but we also attempt and justify a widening of the established definition of what is considered NPR. In the individual Chapters, we identify typical stylistic elements of the different NPR styles. We list problems that need to be solved in order to implement the various renderers. Standard solutions available in the literature are introduced and in all cases extended and optimised. In particular, we extend the lighting model of the comic renderer to include a specular component and introduce multiple inter-related but independent geometric approximations which greatly improve rendering performance. We implement two completely different solutions to random perturbation sketching, solve temporal coherence issues for coal sketching and find an unexpected use for 3D textures to implement hatch-shading. Textured brushes of painterly rendering are extended by properties such as stroke-direction and texture, motion, paint capacity, opacity and emission, making them more flexible and versatile. Brushes are also provided with a minimal amount of intelligence, so that they can help in maximising screen coverage of brushes. We furthermore devise a completely new NPR style, which we call super-realistic and show how sample images can be tweened in real-time to produce an image-based six degree-of-freedom renderer performing at roughly 450 frames per second. Performance values for our other renderers all lie between 10 and over 400 frames per second on homePC hardware, justifying our real-time claim. A large number of sample screen-shots, illustrations and animations demonstrate the visual fidelity of our rendered images. In essence, we successfully achieve our attempted goals of increasing the creative, expressive and communicative potential of individual NPR styles, increasing performance of most of them, adding original and interesting visual qualities, and exploring new techniques or existing ones in novel ways. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
  • Full Text:
  • Date Issued: 2002

An analysis of neural networks and time series techniques for demand forecasting

  • Authors: Winn, David
  • Date: 2007
  • Subjects: Time-series analysis , Neural networks (Computer science) , Artificial intelligence , Marketing -- Management , Marketing -- Data processing , Marketing -- Statistical methods , Consumer behaviour
  • Language: English
  • Type: Thesis , Masters , MCom
  • Identifier: vital:5572 , http://hdl.handle.net/10962/d1004362 , Time-series analysis , Neural networks (Computer science) , Artificial intelligence , Marketing -- Management , Marketing -- Data processing , Marketing -- Statistical methods , Consumer behaviour
  • Description: This research examines the plausibility of developing demand forecasting techniques which are consistently and accurately able to predict demand. Time Series Techniques and Artificial Neural Networks are both investigated. Deodorant sales in South Africa are specifically studied in this thesis. Marketing techniques which are used to influence consumer buyer behaviour are considered, and these factors are integrated into the forecasting models wherever possible. The results of this research suggest that Artificial Neural Networks can be developed which consistently outperform industry forecasting targets as well as Time Series forecasts, suggesting that producers could reduce costs by adopting this more effective method.
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  • Date Issued: 2007

Using a multi-method approach to understand the movement patterns and the associated environmental correlates of an iconic West African recreational fish

  • Authors: Winkler, Alexander Claus
  • Date: 2019
  • Subjects: Carangidae fishing , Carangidae -- Migration , Carangidae -- Namibia , Carangidae -- Angola , Fish tagging , Carangidae -- Benguela Current , Underwater acoustic telemetry , Ocean temperature -- Physiological effect , Fishes -- Effect of temperature on
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/76530 , vital:30597
  • Description: The leerfish (Lichia amia), is a large, primarily coastal recreational fish species with a distribution extending from Portugal down the west coast of African to southern Mozambique. Owing to its large size (30 kg), strong fighting abilities and habit of taking surface artificial lures, this species has taken on an iconic stature among shore-based recreational anglers. Its reputation has made it an important angling tourism species that makes an important contribution to the economy of developing countries. For example, the species brought US$243 per harvested kilogramme into the local southern Angola economy. Despite its high value, little is known about its movement patterns in the northern Benguela coastal region, a region which includes southern Angola and northern Namibia. While much is known about the migratory patterns of the South African stock of L. amia, recent molecular studies have shown that the northern Benguela stock of L. amia has been isolated from the South African population for at least two million years, a consequence of the development of the cold Lüderitz upwelling cell in southern Namibia. Although the global population of L. amia is considered a single species, prominent biogeographic barriers within its distribution and subtle morphological differences between specimens captured within its tropical versus warm-temperate distribution suggest otherwise. A multi-method approach incorporating passive acoustic telemetry (PAT), recreational catch-per-unit-effort (CPUE) and conventional tagging (CT) in southern Angola, as well as recreational fisher-ecological knowledge (FEK) from Namibia, was used to investigate the large-scale movement patterns of L. amia within the northern Benguela coastal region. While each method had its own associated limitations, the combination provided a holistic picture of the population's seasonal migratory patterns. Furthermore, PAT successfully identified partial migration with 25% vs 75% of monitored fish exhibiting resident (movements < 100 km) or migratory (movements > 100 km) behaviour, respectively. Further behavioural diversity was observed with ‘resident’, ‘roaming’ and ‘embayment’ contingents identified based on varying levels of affinity to certain habitats. The presence of both resident and migratory individuals within the northernmost study during June and July, combined with available biological information, suggested that area-specific spawning may take place. While PAT, CPUE and CT largely aligned in determining area specific high-area use, results from network analyses and mixed effects models conducted on the PAT data supported the spawning hypothesis, with anomalous behaviour around specific receivers during the spawning season. All fish, regardless of behavioural contingent, displayed similar movement behaviour during the spawning season and this was driven by factors generally associated with reproduction, such as lunar illumination. Interestingly, these drivers were different from those that determined the area specific use of individuals outside of the spawning season. The environmental drivers of longshore migration into the northern study site were identified as a decline in water temperature and shorter day lengths. The results of this study highlight the importance of using a multi-method approach in determining migratory movement behaviour, area specific area use, and stock structure of key fisheries species. The identification of different behavioural contingents highlights the importance of acknowledging individual variation in movement and habitat-use patterns. This is particularly relevant as future climate change and spatiotemporal variation in fishing effort may artificially skew natural selection processes to favour certain behavioural groups. This study also highlighted the importance of scientists forming relationships with resource-users, such as recreational angling lodges in areas where limited research has been conducted. This is particularly relevant within the West African context where little is known about many of the fish species that are being increasingly targeted by tourism angling ventures.
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  • Date Issued: 2019

Taxonomy and life history of the zebra seabream, Diplodus cervinus (Perciformes: Sparidae), in southern Angola

  • Authors: Winkler, Alexander Claus
  • Date: 2014
  • Subjects: Diplodus -- Classification Fish populations -- Angola Diplodus -- Angola Diplodus -- South Africa Diplodus -- Morphology Fisheries -- Angola Sparidae
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:5361 , http://hdl.handle.net/10962/d1012062
  • Description: The zebra sea bream, Diplodus cervinus (Sparidae) is an inshore fish comprised of two boreal subspecies from the Gulf of Oman and the Mediterranean / north eastern Atlantic and one austral subspecies from South Africa and southern Angola. The assumption of a single austral subspecies has, however, been questioned due to mounting molecular and morphological evidence suggesting that the cool Benguela current is a vicariant barrier that has separated many synonymous inshore fish species between South Africa and southern Angola. The aims of this thesis are to conduct a comparative morphological analysis of Diplodus cervinus in southern Angola and South Africa in order to classify the southern Angolan population and then to conduct a life history assessment to assess the life history impact of allopatry on this species between the two regions. Results of the morphological findings of the present study (ANOSIM, p < 0.05, Rmeristic = 0.42) and (Rmorphometric = 0.30) along with a concurrent molecular study (FST = 0.4 – 0.6), identified significant divergence between specimens from South Africa (n = 25) and southern Angola (n = 37) and supported stock separation and possibly sub-speciation, depending on the classification criteria utilised. While samples from the two boreal subspecies were not available for the comparative morphological or molecular analysis, comparisons of the colouration patterns between the three subspecies, suggested similarity between the southern Angola and the northern Atlantic / Mediterranean populations. In contrast, the colouration patterns between the southern Angolan and South African specimens differed substantially, further supporting the morphological and molecular results. The distinct morphological divergence between the southern Angolan and South African populations was not reflected within the life history traits of both populations. A combination of methods, including length/age frequency analyses, adult sex ratios and histological analysis was used to determine that this species is a rudimentary hermaphrodite in southern Angola. Peak spawning season was observed between June and July. The overall sex ratio (M: F) was 1:1.52 with females dominating smaller younger size classes and 50% maturity was attained at 210 mm FL and 4.6 years. Females [L(t) = 287.5(1-e⁻°·¹⁸⁽t⁻²·⁸⁴⁾)] grew significantly faster (LRT, p < 0.05) than males [L(t) = 380.19(1-e⁻°·°⁶⁽t⁻⁷·¹²⁾)]. The higher maximum age of the southern Angolan population of D. cervinus (43 years) was older than that of South African individuals sampled in the tsitsikamma national park. The similarities in the life history of the two austral populations are probably a consequence of similar selective pressures in the similar warmtemperate habitats. Evidence to support the above comments was found in the feeding study which showed that the South African and Angolan populations were almost identical, with both populations feeding primarily on amphipods and polychaete worms throughout ontogeny. In contrast, the diet of their boreal conspecifics from the Mediterranean was different, where larger individuals tended to select larger, and more robust, prey items. The life history differences observed between the boreal and austral populations can be attributed to either sampling bias or environmental factors. Sampling biases included the use of different age and growth estimation techniques, while the environmental factors would include differential selective pressures most likely driven by different resource availability and exploitation. The present study provides crucial baseline life history information of a potentially exploitable species off southern Angola as well as information on the life history plasticity of the species. Unfortunately, the current lack of uniformity in the methods used to estimate life history parameters between studies conducted on the boreal and austral populations have complicated our understanding of the evolution of various life history trends in sparid fish. From a management perspective however, the results from the present study can be used to propose management strategies for an emerging trap fishery in southern Angola. Using a balanced exploitation fishery approach (harvesting up to the size-at-100% maturity), the size of the fish traps entrance was calculated based the morphological information from this and other small sparid species that are targeted and was estimated to be 62 mm.
  • Full Text:
  • Date Issued: 2014

Post-impoundment population dynamics of non-native common carp Cyprinus Carpio in relation to two large native cyprinids in Lake Gariep, South Africa

  • Authors: Winker, Henning
  • Date: 2011
  • Subjects: Cyprinidae -- South Africa -- Gariep Dam Carp -- South Africa -- Gariep Dam Fish populations -- South Africa -- Gariep Dam Fishes -- Physiology -- South Africa -- Gariep Dam Barbus aeneus -- South Africa -- Gariep Dam Mudfishes -- South Africa -- Gariep Dam Freshwater fishes -- South Africa -- Gariep Dam
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5311 , http://hdl.handle.net/10962/d1005156
  • Description: To contribute to the understanding of the invasion biology of common carp Cyprinus carpio in southern Africa, this thesis investigated the life history, relative abundance, long-term population demographics and trophic niche utilisations of non-native common carp C. carpio in relation to two endemic cyprinids, Orange River mudfish Labeo capensis and smallmouth yellowfish Labeobarbus aeneus in South Africa‟s largest impoundment, Lake Gariep. The growth zone deposition rates in astericus otoliths of the three species were validated as biannual for C. carpio and as annual for L. capensis and L. aeneus, which allowed for reliable estimation of lengths-at-age upon which growth, age-at-maturity and mortality rates could be estimated. Cyprinus carpio exhibited fast growth, matured relatively early at two years of age and attained a maximum age of seven years. Labeo capensis grew significantly slower, but attained older ages of up to 12 years. Females showed notably delayed maturation at approximately six years of age. The life history parameter estimates for L. aeneus were similar to those of L. capensis. These species-specific life history characteristics contributed to a substantially higher population growth potential of C. carpio compared to L. capensis and L. aeneus. Delta-lognormal and delta-gamma Generalized Linear Models (GLMs) were used to analyse patterns of relative abundance of L. capensis, L. aeneus and C. carpio. The application of these GLMs was necessary to account for large proportions of zeros and strong skewness in the catch-per-unit-effort (CPUE) from experimental gillnet and fisheries-dependent angler surveys. Confidence intervals around predicted abundance indices were obtained through the development of a generalised parametric bootstrap procedure. The resulting standardised abundance indices were coupled with results from analysis of stable isotope ratios of fish tissues and potential food resources and revealed that C. carpio was mainly confined to soft-bottom habitats, where it predominantly foraged on benthic invertebrates. Labeo capensis was abundant in a wide range of benthic habitats and was consumed basal food resources such as detritus. Labeobarbus aeneus was found to feed mostly on pelagic zooplankton. There were no significant interspecific differences in trophic niche space, suggesting limited resource competition among the three species. Standardised historical and contemporary gillnet CPUE data indicated slow population growth rates of L. capensis and L. aeneus during the first ten years postimpoundment, but showed high biomass levels some four decades after impoundment. These results could be corroborated by stochastic age-structured production model (ASPM) simulations. In contrast to the two endemic species, the gillnet CPUE of C. carpio showed a clear „boom and bust‟ pattern, which, based on ASPM simulations, could be best explained by increased food availability during the first five years postimpoundment, followed by suboptimal conditions thereafter. Together, these results provided evidence that the establishment of the C. carpio population did not prevent the slow but successful long-term establishment of the two large endemic cyprinids. Both endemic fishes revealed specialised feeding within the impoundment.
  • Full Text:
  • Date Issued: 2011
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