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The psychological sequelae of involvement in combat: a preliminary investigation

  • Authors: Hodgson, Shane Ralph Colin
  • Date: 1992
  • Subjects: War -- Psychological aspects , War victims -- Mental health , Post-traumatic stress disorder
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:2993 , http://hdl.handle.net/10962/d1002502 , War -- Psychological aspects , War victims -- Mental health , Post-traumatic stress disorder
  • Description: The psychological sequelae of being involved in combat are only recently coming to be understood. Most of the available data are from research conducted on help-seeking Vietnam veterans in the United States, and very little work has been done in South Africa. There does not as yet appear to be any instrument designed specifically to detect combat-related psychopathologies amongst soldiers who are still in active service, either in the USA or in South Africa. Combat involvement has been shown to lead to a high incidence of combat stress reaction. This in turn has shown that it can predispose sufferers to the development of a Post-traumatic Stress Disorder. It is thus expected that there would be significantly higher incidences of reported symptoms of stress disorders amongst soldiers exposed to high levels of combat as compared with a similar group of soldiers who had no combat involvement. This study used a self-reporting questionnaire, developed in the USA but adapted for use in South Africa, to allow the soldiers in the study to rate the severity of various symptoms derived from the DSM-III criteria for Post-traumatic Stress Disorder. A Beck Depression Inventory was also administered to eliminate any persons who nay have been exhibiting symptoms of depression, as this would have confounded the results. Both questionnaires were administered to serving members of the Permanent Force of the South African Defence Force, with one group being members of various high-combat units based in what was then South West Africa, and the other group being non-combat or Headquarters elements. As a precondition of the study, absolute confidentiality of the respondents and their units was maintained. The study found the expected higher scores in the high-combat group, and also showed that the Keane questionnaire has a good coefficient alpha in South Africa. The study closes with several recommendations for further research, especially in the light of the new PTSD criteria in the DSM-IIIR.
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  • Date Issued: 1992

Umgangxo wamakhehla

  • Date: 1955-03-03 , 2023-09-01
  • Subjects: Beadwork , Body harness
  • Language: English
  • Type: realia , Personal adornment
  • Identifier: http://hdl.handle.net/11260/8643 , vital:68064
  • Description: Umgangxo wamakhehla is a body harness of an old man body harness in flat bead strips and chains, Pink and navy beads denote age, The necklace forms part of a beadwork collection that was acquired from Mrs Broster in 1992. , Purchased from Mrs Joan Broster , Forms part of: Walter Sisulu University Beadwork Collection
  • Full Text: false
  • Date Issued: 1955-03-03

Up Beat Issue Number 1 1992

  • Authors: SACHED
  • Date: 1992
  • Subjects: SACHED
  • Language: English
  • Type: text
  • Identifier: http://hdl.handle.net/10962/116175 , vital:34329
  • Description: It’s tough being a teenager. There’s pressure from all sides - your friends, parents and teachers. You’ve got lots of questions that no-one will answer. If you want to get on top of your world, don’t be without Upbeat in 1992. This year Upbeat is bigger, brighter and better than ever. There are more pages, more competitions, music and fashion. And the good news is you can find us everywhere - on the street, in your corner shop or in the CNA. We also have special offers for teachers and students. Subscribe before April and you could win prizes worth R1 000. Upbeat also helps you with your school work. But it’s not like learning in school. This is learning with a difference. We open your eyes to the world around you. In this issue we’ll take you to a night club in Cape Town where everyone is ‘hipping and hopping.’ Meet a young girl in a faraway land, most of us know nothing about - Pakistan. For comic lovers there’s our action packed comic ‘Taxidriver’. Follow the adventures of Kabu a taxidriver from Sekhukhuneland in the Transvaal and learn all about South Africa in the 1950s. It’s a great way to learn history! No issue is too hot for us to handle. In this Upbeat young people share secrets about their relationships. Our advice page answers your questions on sex education and careers. We believe young people in this country need a voice. Each issue is packed with poems, stories, news and views of young people around the country. So here’s your chance to tell the world what you think, express your true feelings in a poem or ask those questions grown-ups don’t like to answer. Write to us, it is your magazine. Upbeat is for teachers too. Lots of teachers around the country use Upbeat to promote a different kind of learning in their classes: learning that gets students thinking, helps them understand their world and most of all that’s FUN. Read how Mrs Naylor a teacher from Cape Town uses Upbeat with her students. Finally, did you know you have rights? The right to be heard is just one of them. The Rights of Young People is the theme of our calendar this year. And it’s FREE in this issue for you to put up on your classroom or bedroom wall.
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  • Date Issued: 1992

The surface geology of the Lavino Chrome Mine of the farm Grootboom 336KT, eastern Transvaal

  • Authors: Tinney, Christopher Bruce
  • Date: 1992
  • Subjects: Chromium ores -- Geology -- South Africa -- Mpumalanga
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5067 , http://hdl.handle.net/10962/d1013404
  • Description: A mapping project of the surface geology of the Lavino chrome mine and its surroundings was initiated in order to establish the surface geological relationships in the area. In so doing the chromitite layer presently being mined has been identified and potential exploration targets in the area have been outlined. The Lavino Chrome mine field area is situated within the eastern lobe of the Bushveld Igneous Complex. The area is bounded by in the north by the Steelpoort Lineament, in the west by the Dwars River fault and in the east by the contact with the Transvaal Sequence floor rocks. Layered igneous rocks (pyroxenites, norites and anorthosites) of the Rustenburg Layered Suite dominate the geological landscape at the Lavino mine. The fact that outcropping igneous rocks of the Critical Zone abut directly against the quartzite floor rocks on the mine property makes this area unique in the Bushveld Complex. The hills in the field area are capped by mafic/ultramafic iron-rich sheet - like bodies. Extensive strike-slip faulting is seen in outcrop in the area to the north/northwest of present mining operations. On the basis of field relationships, the main chromitite layer presently being mined at Lavino is identified as the Middle Group chromitite layer MG 1. Three other prominent chromitite layers stratigraphically associated with MG 1 are identified as the Middle Group chromitites MG 2, MG 3 and MG 4. Several other less prominent outcropping chromitite layers are tentatively identified as those belonging to the Lower and Upper group of chromitites. The disconformable nature of the contact between the layered igneous rocks and the Transvaal Sequence floor rocks has resulted in the development of a wedge of undifferentiated pyroxenites in the north of the field area. The economically important LG 6 chromitite layer may be developed in subcrop within this wedge.
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  • Date Issued: 1992

Inkciyo yentombi

  • Date: 1954-07-01 , 2023-09-01
  • Subjects: Beadwork , Genital girdle
  • Language: English
  • Type: realia , Personal adornment
  • Identifier: http://hdl.handle.net/11260/8554 , vital:68012
  • Description: Inkciyo yentombi, a genital girdle of a maiden, an ornate apron of flat bead strip, and three rows of bead fringes supported by two rows of brass washers threaded on goat skin thongs. These washers are handed down by a grandmother to her fovourite granddaughter usually at puberty and the girdle is worn until the menopause stage. , Purchased from Mrs Joan Broster , Forms part of: Walter Sisulu University Beadwork Collection
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  • Date Issued: 1954-07-01

A cost-benefit analysis of electricity supply in a developing country, with reference to Venda

  • Authors: Themeli, Tshimangadzo Booi
  • Date: 1992
  • Subjects: Electrification -- Economic aspects -- South Africa -- Venda , Electric utilities -- South Africa -- Venda , Cost effectiveness , Electrification -- Cost effectiveness
  • Language: English
  • Type: Thesis , Masters , MCom
  • Identifier: vital:1022 , http://hdl.handle.net/10962/d1002757 , Electrification -- Economic aspects -- South Africa -- Venda , Electric utilities -- South Africa -- Venda , Cost effectiveness , Electrification -- Cost effectiveness
  • Description: This study concentrates specificaUy on assessing those elements of private and external costs and benefits which need to be accounted for in analyzing the role of electricity supply in a developing region. To facilitate this aim, three interrelated questions are addressed. The first question examines the reasons why a critical need for electrification in developing areas exists. In this regard, a selective review of the literature on development economics is offered, illuminating the previous neglect of the rural dimension in development and the associated problems of poverty and inequality, a lack of infrastructure and the general inability to fulfill basic needs. The second question is devoted exclusively to an economic analysis of the supply of electricity in developing areas. A broad theoretical review on whether an unregulated or regulated (private or public) sector should be responsible for the provision of electrification is presented. This evaluation highlights the various welfare implications and efficiency considerations that appear to be relevant in the present context. The final question, which constitutes the central proposition of the thesis, establishes how electrification should be supplied in developing areas. To this end, the conditions specific to a region in Venda are discussed. An attempt is made to identify the private and external costs and benefits relating to electricity supply and the corresponding costs and benefits pertaining to alternative sources of energy. Since the incidence and nature of these costs and benefits could only be ascertained from individual households, it was deemed necessary to undertake a questionnaire study of residents in Makwarela township and its periurban settlement of Lufule-Tshisele. A number of basic trends were evident from the research results. As far as the various benefits are concerned, respondents tended to place a much higher value on both the private and external benefits associated with electricity than its alternatives. At the same time, the survey found that although the private (or monetary) cost of electricity far exceeded the corresponding cost of alternative energy sources, the external costs were significant in the case of alternative energy sources, but virtually non-existent in the case of electricity. On the whole, the Venda survey seems to suggest that an economic case can be made for involving the broader community in subsidising the supply of electricity in Makwarela, Lufule-Tshisele and other areas. While such a subsidy can perhaps be justified on distribution grounds alone, and more specifically in terms of the rapid and pronounced effect it is likely to have on the quality of life in the region, its real worth lies in the fact that it may confer certain external benefits on the community.
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  • Date Issued: 1992

Up Beat Issue Number 5 1992

  • Authors: SACHED
  • Date: 1992
  • Subjects: SACHED
  • Language: English
  • Type: text
  • Identifier: http://hdl.handle.net/10962/116248 , vital:34343
  • Description: Richard is in Std 9. He sits in the same row as Thabo and Mike. They are his great friends. Every day at break they sneak out the schoolyard to go and smoke dagga. Richard doesn't like smoking. He wants to say no. But he is scared his friends won’t like him if he does. He doesn’t want to risk that. These are his chommies! They all watch soccer together and share secrets about girls. Maybe you find yourself in Richard’s position. You are also too scared to say no to your friends. Try to be brave and stand up for yourself. Tell your friends that you don’t want to smoke, because drugs are harmful. You may be surprised to find that someone else in the group agrees with you. He was just too scared to say so. Or maybe your friends will cut you out. You’ll feel lonely for awhile but others will come to respect you. We all look up to people who make a stand. It is hard to go against your friends. But you must learn to do what’s right for you. Arm yourself with information. Read, listen and learn. Then make your choice. Upbeat is filled with important information to help you make decisions about your life. In this issue read why Prophets of the City say No to drugs. Don’t miss our hot debate on sex education. We’ve got information on AIDS. So tell your friends about it and help stop the disease spreading. We all love listening to music. But do you know how a record is made? Find out all about the recording industry on page 17. That will really impress your friends! When they look surprised and say ‘how do you know all that’, just say you read it in Upbeat. You’ll be a winner at parties.
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  • Date Issued: 1992

Guidelines to the evaluation of selectively mined, open pit gold deposits during the exploration stage of mine creation

  • Authors: Pelly, Frederick Douglas Peter
  • Date: 1992
  • Subjects: Mining geology , Gold ores -- Geology , Gold mines and mining -- Economic aspects
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4970 , http://hdl.handle.net/10962/d1005582 , Mining geology , Gold ores -- Geology , Gold mines and mining -- Economic aspects
  • Description: This dissertation studies the evaluation of selectively mined, open pit gold deposits during the exploration stage of the mine's life. Since 1970 a large number of selectively mined, open pit gold mines have come into operation. The most common deposits include epithermal vein, mesothermal lode and laterite gold deposits. In general the deposits are characterized by small tonnages (1-20 million tonnes), relatively high grades (2-10 grams per tonne gold), submicroscopic to coarse gold, inexpensive mining, and both free milling and refractory ores.The key components that require evaluating during the exploration period are the deposit's geology, ore reserves, pit design, ore metallurgy and environmental impact. Feasibility studies are the main vehicle by which to report and guide the exploration programme. During the exploration period a company may undertake an initial (geological feasibility), second (preliminary mine feasibility) and third (final feasibility) delineation programme in order to gather sufficient data to justify a mine development decision. The responsibility of evaluating the mineral prospect lies primarily with the exploration geologist and mining engineer. Broad experience, a professional attitude, a thorough understanding of mining economics, and a high level of geological, engineering and technical skills are traits required by the evaluators. In order for mining companies to make sound investment decisions the geographical, geological, mining, metallurgical, environmental, marketing, political and financial aspects affecting the economic potential of the venture must be integrated so that the likely costs, risks and returns of the investment alternative are quantified. Ultimately, it is the economic analysis of these three items that determine whether the mineral prospect is developed into a mine I delineated further I retained until economic circumstances improve, or abandoned. To assess the costs, risks and returns, extensive use of the risk analysis is advocated throughout the exploration period . When combined with intelligent judgement of the intangible risk elements, the probabilistic distribution of discounted cash flows are invaluable in making sound investment decisions. However, the economic analysis is only as good as the information on which it is founded. Accurate and representative field data is the most important prerequisite to successfully evaluating and developing a new mine.
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  • Date Issued: 1992

Influence of the oil phase dispersion in a cream base on the in vivo release of betamethasone 17-valerate

  • Authors: Haigh, J M , Smith, E W , Meyer, E , Fassihi, A R
  • Date: 1992
  • Language: English
  • Type: Article
  • Identifier: vital:6365 , http://hdl.handle.net/10962/d1006065
  • Description: Release of betamethasone valerate (betamethasone 17-valerate) from 3 extemporaneous cream formulations (1 control, 1 containing propylene glycol, and 1 containing \b/-cyclodextrin) and a commercial cream formulation (Betnovate) was compared using the human skin blanching assay in 12 healthy male volunteers. All 3 extemporaneous formulations showed similar drug release rates, equivalent to or better than the commercial preparation containing betamethasone in a 10 fold higher concentration. Electron microscopic examination showed considerably finer dispersion of the oil phase in the extemporaneous formulations. It was concluded that the increased surface area available for partitioning of betamethasone between the cream and the skin is responsible for the improved topical availability of the drug from the extemporaneous formulations.
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  • Date Issued: 1992

Domestic strategies of rural Transkeian women

  • Authors: Cloete, Laura
  • Date: 1992
  • Subjects: Rural families -- South Africa -- Transkei Women -- South Africa -- Transkei Women -- South Africa Sex role -- South Africa -- Transkei Rural women -- South Africa -- Transkei Transkei (South Africa) -- Social conditions Transkei (South Africa) -- Rural conditions Transkei (South Africa) -- Economic conditions
  • Language: English
  • Type: Book , Text
  • Identifier: http://hdl.handle.net/10962/2014 , vital:20247 , ISBN 0868102342
  • Description: This research, originally undertaken as part of a B.A.(Honours) Degree in Anthropology, has several aims. Firstly, it aims to reveal the various community options available to women in rural Transkei for coping with their domestic activities in the face of the large-scale absence of men. It will analyse the rationale behind the choices and their consequences for the women’s workload. Secondly, this will illuminate gender and generational roles and attitudes of community members, present and absent, in the community. The focus, in this case, will be predominantly on women, however. Thirdly, and finally, this research will analyse the relationships of power between men and women, and between adults and children by examining the various influences, such as religion and education, which constrain and coerce their behaviour and attitudes. From this, we should be left with an illuminating picture of the forces under which women operate in rural Transkei; and with some insight into their behaviour and attitudes, their beliefs and aspirations and into their lives. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
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  • Date Issued: 1992

A critical analysis of the marketing of mohair in South Africa with special reference to the period 1963 to 1989

  • Authors: Norton, Eustace Herbert Fraser
  • Date: 1992
  • Subjects: Mohair -- South Africa -- Marketing , Mohair industry -- South Africa
  • Language: English
  • Type: Thesis , Masters , MCom
  • Identifier: vital:1020 , http://hdl.handle.net/10962/d1002755 , Mohair -- South Africa -- Marketing , Mohair industry -- South Africa
  • Description: The objective of the research was to determine the extent to which marketing in general, and the Mohair Scheme in particular, played a part in the re-emergence of South Africa as the world's leading mohair producer. The two major components of the Scheme, the 'voorskot', or initial payment, and reserve prices were analysed separately. In an adaptive expectations, distributed lag model of supply adjustment, only the weighted rainfall and the average real net price of mohair during the previous season, were found to be important determinants of mohair production. The significant negative correlation between the average real net 'voorskot' price and mohair production was contrary to expectations, and probably due to the 'voorskot' always having been set well below the market price. The 'voorskot' may nevertheless have played an important part in making the Scheme as a whole acceptable to producers. As no record is kept of the reserve price, its influence was tested indirectly in two stages. In the first, its influence on price stability was determined by a comparison of ranges, standard deviations and variances, and by several multiple linear demand regressions. Three of the four models showed clearly that price stability was increased by the Mohair Scheme. In the second stage, formulae and diagrammatic analyses were used to assess the welfare gains and losses resulting from the Mohair Scheme. There was a welfare gain to local producers and most of the welfare costs of the Scheme were borne by foreign consumers. With this gain to producers and the more stable price, it was concluded that the reserve price had stimulated mohair production. It was therefore established that the Mohair Scheme had played a major part in the re-emergence of South Africa as the world' s leading mohair producer. Nevertheless, in view of the massive stockpiling in recent seasons, because the reserve price was set too high, the result was a substantial loss to the Scheme; it was therefore recommended that the Mohair Scheme be discontinued or, at least, that the reserve price should be set at a much lower long-run, market clearing level.
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  • Date Issued: 1992

The interactive effects of light, temperature and CO₂/O₂ ratios in photosynthesis of Coix lachryma-jobi L

  • Authors: Mjwara, Jabulani Michael
  • Date: 1992
  • Subjects: Coix , Plants -- Effect of light on , Plants -- Effect of oxygen on , Plants -- Effect of carbon dioxide on , Photosynthesis , Plants -- Effect of temperature on
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4216 , http://hdl.handle.net/10962/d1003785
  • Description: A portable infra red gas analyzer was used to investigate the interactive effects of light, temperature, and CO,jO, ratios under controlled environmental conditions in an attempt to model gas exchange characteristics of Coix Iachryma-jobi L. Plotting light response curves as a function of temperature (20, 25 30 and 35°C) revealed no sign of light saturation even at a photosynthetic photon flux density (PPFD) close to 2000 !Lmol m-' sol. High net assimilation rates (A) of approximately 24 !Lmol CO, m"s'! were realized at 30-35°C. Assimilation (A) versus internal CO, partial pressure (C,) curves showed a steep rise with increase in C, but saturated at approximately 150 (JLII-!) and all the results, either in the absence or presence of 0" showed a similar response under all temperature regimes. C. Iachryma-jobi exhibited low CO, compensation points cr ) between 0 and 10 JLlI-! under similar experimental temperatures and either at 0 or 21%0,. The slopes of double reciprocal plots of llA versus llCi, were nearly identical and crossed the yintercept at almost identical points under all 0, concentrations. These data indicate first; that there was no apparent 0, inhibition and second; indicated that the apparent inhIbitor constant (K,) for 0, at the site of carboxylation did not change with increase in [OJ from 0 to 21% oxygen. These observations were further confirmed by results obtained from the analysis of apparent carboxylation efficiency (CE, as defined as the slope of response of A to increasing CO,), as no inhibition of A with increase of [OJ occurred. These characteristics were consistent with typical features of C,photosynthesis. The absence of 0, inhibition and low r values indicated that an efficient CO, concentrating mechanism which eliminates photorespiration exists in C. Iachryma-jobi. At the light microscope level, leaf anatomy exhibited typical C, structure viz. bundle sheath with large chloroplasts and this sheath is further surrounded by a radiate Kranz mesophyU cells. Furthermore the anatomical features suggested that C. wchryma-jobi was an NADP-ME species. Stomatal conductance (g,) to assimilation (g,/A) indicated an increase in A with decrease in g" an essential feature of improving water use efficiency (WUE), but one which drastically reduces CO, diffusion rate. The physical lintitation (stomatal lintitation, t) to CO, diffusion under various [0,] and temperatures, but constant PPFD, did not exhibit statistically significant change in t values at either 0 or 21% a, within each temperature regime, however there was a marked decrease in t as the plant approached its optimum photosynthetic temperature.
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  • Date Issued: 1992

A study of the biopharmaceutics and pharmacokinetics of the macrolide antibiotic, erythromycin

  • Authors: Terespolsky, Susan Ann
  • Date: 1992
  • Subjects: Erythromycin -- Bioavailability , Erythromycin -- Pharmacokinetics
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:3795 , http://hdl.handle.net/10962/d1003273 , Erythromycin -- Bioavailability , Erythromycin -- Pharmacokinetics
  • Description: Erythromycin, a macrolide antibiotic isolated from Streptomyces erythreus, was first introduced into clinical medicine in 1952. It is active against most gram-positive bacteria, some gram-negative bacteria and is currently the agent of choice for Legionella pneumophila. Erythromycin is an acid-labile compound rapidly degrading in acidic solutions such as the acid environment of the stomach. As such, erythromycin absorption following oral administration of solid dosage forms is relatively poor. Accordingly there have been various approaches used to protect the drug against gastric inactivation. These precautions include enteric-coating of tablets, capsules or pellets of erythromycin base, the synthesis of acid stable 2' esters of erythromycin (ethylsuccinate and propionate) and salts of these esters (erythromycin estolate), and more recently, the synthesis of a range of new acid-stable, semi-synthetic macrolide antibiotics. The 2' esters are antimicrobially inactive or much less active than the parent compound and must be converted to the free erythromycin base in vivo in order to exhibit antibacterial activity. Intrinsic dissolution rates determined on raw material can provide extremely useful information relating to the gastrointestinal absorption of drugs from solid dosage forms. The large inter- and intrasubject variability associated with erythromycin base has, to date, mainly been attributed to gastric acid inactivation of the drug. However, changes in duodenal pH resulting in altered solubility and intrinsic dissolution rates may account for the observed variability. Thus, the intrinsic dissolution rates of erythromycin base at pH 6.0, 6.5, 7.0, 7.5 and 8.0 were compared in order to investigate the possible effects of pH changes which may occur in the duodenal contents, on the in vivo dissolution and subsequent absorption of this compound. The standard intrinsic dissolution rate test procedure employing a rotating disc of pure erythromycin base powder which only allows for dissolution from a constant surface area, was adapted and the drug quantitatively determined by reversed phase high performance liquid chromatography (HPLC) using ultraviolet detection. Results of intrinsic dissolution studies at both 22°C and 37°C indicate that the solubility, and therefore the rate of dissolution of erythromycin base is pH dependent, being more soluble at pH 6.0 than pH 8.0 (an approximate 800 times and 1000 times reduction in the amount dissolved after 30 minutes, at 22°C and 37°C respectively, when the pH of the medium was increased from 6 to 8). Although the stability of erythromycin and its ester derivatives in aqueous acidic solutions has been well documented, very little has been reported on the compound's stability in organic solvents. Methanol is recommended by official drug compendia (U.S.P. and B.P.) for use in erythromycin identification tests as well as in the sample preparation steps during assay procedures. Thus, the effect of methanol and acetonitrile, organic solvents of similar polarities and densities, on the stability of erythromycin base, erythromycin ethylsuccinate, propionyl erythromycin and erythromycin estolate at room temperature (22°C ± 0.5°C), using HPLC with electrochemical detection, was investigated. Erythromycin base is relatively stable in both methanol and acetonitrile, remaining intact for over 168 hours in acetonitrile and showing less than 5% degradation in methanol over the same period. Erythromycin ethylsuccinate in acetonitrile shows less than 5% degradation over 168 hours whereas in methanol, rapid hydrolysis occurs resulting in almost total conversion to base within 40 hours. Approximately 87% of erythromycin propionyl ester remained intact after 168 hours in acetonitrile whilst methanol caused rapid hydrolysis to erythromycin base (35% remaining after 28 hours). Erythromycin estolate appeared to be unstable in both acetonitrile and methanol. In acetonitrile, only 13% of the estolate remained intact after 168 hours, whereas in methanol, the reaction was much more rapid with 35% of the estolate remaining after 28 hours. The use of methanol as a solvent for erythromycin estolate reference standards is thus contraindicated. A number of conflicting reports on the half- life as well as the body compartment model that best describes erythromycin base serum concentration-time profiles (lBCM generally used to describe orally administered erythromycin, whilst a 2BCM has been used to describe erythromycin administered intravenously), appear in the literature. These differences may be largely attributed to the sampling period (between 6 and 12 hours) used in the repective studies. The objective of this study was to determine the body compartment model that best describes erythromycin base serum concentration-time curves by increasing the sampling time to 24 hours. In addition, the effect of chronic dosing of erythromycin on erythromycin pharmacokinetics, in the same group of subjects, was investigated. The single and multiple oral dose pharmacokinetics of erythromycin enteric coated base pellets within a gelatin capsule (250mg), were studied in 6 healthy, normal volunteers (19.5 ± 0.76 years, 71.5 ± 8.18 kg, 180.33 ± 5.99 cm). Furthermore, steady state concentrations were predicted using the pharmacokinetic parameters obtained from the single dose study, and compared with those obtained in the multiple dose study. Plasma concentrations were determined using a sensitive high-performance liquid chromatographic method with electrochemical detection. For the single dose study, after a tlag of 2.5 ± 0.71 hr, Cmax (1.12 ± 0.47 μ/ml) was reached at a tmax of 4.08 ± 0.93 hr post dose, with serum concentrations ranging from 0.31 - 1.62 μ/ml. The half-life was found to be 5.42 ± 1.31 hr. On multiple dosing (250mg six hourly), serum concentrations for the fifth, ninth and thirteenth dosing intervals ranged from 0.67 - 2.92 μ/ml, 1.69 - 3.65 μ/ml and 0.61 - 3.01 μ/ml, occurring at 3.75 ± 0.69 hr, 3.17 ± 1.03 hr and 3.17 ± 1.03 hr post dose with a Cmax of 1.89 ± 0.68 μ/ml, 2.35 ± 0.70 μ/ml and 1.94 ± 0.74 μ/ml, respectively. The area under the serum concentration- time curve for the single dose study (AUC₀₋∞) was 4.67 ± 0.88 hr.μ/ml, whilst the AUC₀₋τ. for the fifth, ninth and thirteenth dosing intervals of the multiple dose study were 5.77 ± 1.76 hr.μ/ml, 6.46 ± 1.33 hr.μ/ml and 5.97 ± 2.36 hr.μ/ml respectively, indicating an approximately 33% increase in AUC on chronic dosing of erythromycin. The observed increase in AUC may be a result of increased bioavailability or a decrease in clearance on chronic dosing.
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  • Date Issued: 1992

Interaction of selected fungicides with insoluble bovine skin collagen in the presence of the non ionic surfactant Triton X-100

  • Authors: Fowler, William Mackenzie
  • Date: 1992
  • Subjects: Collagenases -- Research Fungicides -- Research Hides and skins -- Preservation
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4318 , http://hdl.handle.net/10962/d1004976
  • Description: In the leather industry fungicides are often used for the protection of wet-blue leather. These fungicides are usually only sparingly soluble and are therefore formulated together with surfactants in order to increase their solubility and to ensure an even distribution over the surface of the hide after treatment. Solutions containing both fungicides and surfactant are complex. The nature of these solutions was investigated. By means of UV/Vis spectroscopy and viscometry it was shown that the surfactant and fungicides form micelles and mixed micelles in solution. The nature of these micelles and mixed micelles was dependent on the solution temperature as well as on the concentrations of the surfactant and fungicides. At the higher temperatures and concentrations transition to large, possibly rod-shaped, mixed micelles occurred. The interaction between the selected fungicides 2-(thiocyanomethylthio)benzothiazole and n-octyl-4-isothiazol-3-one with bovine skin collagen in the form of both limed and lightly chromed hide powder in the presence of the non ionic surfactant Triton X -100 was investigated. Fungicide uptake was determined by difference measurements on the float solutions at regular intervals during treatment. Binding was rapid with equilibrium being established within the first six hours even for the solutions with the highest surfactant concentration. Binding failed to follow a normal mass-action binding-type isotherm approaching a saturation limit, but increased continuously indicating a co-operative effect whereby binding site affinity actually increased with the amount of ligand bound. Binding was accompanied by a drop in the free surfactant in the solution at the higher biocide levels indicating the formation of complex mixed micelles which bind to the collagen fibres. The uptake and antifungal activity of commercial fomulations of the fungicides on chrome-tanned wet-blue leather was investigated at various treatment temperatures. At lower fungicide treatment concentrations, binding tended to follow a typical mass-action type binding isotherm, increasing slightly with temperature. At higher float concentrations, an inflexion point was apparent beyond which uptake showed a marked increase with concentration. This inflexion point, signifying a change in binding characteristics, occurred at progressively lower concentrations with increasing temperature. Antifungal activity in terms of storage periods to onset of fungal growth was determined on the wet-blue leather cuttings immediately after treatment and drainage and also on sample discs after exhaustive extraction of free fungicide using dichloromethane. Storage performance testing of the various treated wet-blue leathers was carried out by different methods. Residual protective periods showed a curvilinear increase with dosage offer and surface uptake. In the low dosage range treatment temperature had only a relatively slight effect in promoting uptake and improving storage protection. At higher dosages, the influence of temperature on uptake and storage protection was greater due to the increase in surface binding of the fungicides at the elevated temperatures. Only a portion of the fungicide uptake was recovered by direct solvent extraction of the treated wet-blue leather. Solvent extraction reduced storage margins. The storage response in relation to fungicide content was, however comparable after extraction, indicating that both irreversibly bound and physically associated fungicide offered effective protection. Results of the study provide further insight into the mode of interaction of fungicide emulsion dispersion with bovine skin collagen, and the importance of the emulsion dispersions and its stability in determining the uptake of fungicide.
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  • Date Issued: 1992

In vitro effects of three organic calcium channel blockers on the rat pineal gland

  • Authors: Brown, Clint
  • Date: 1992
  • Subjects: Calcium -- Antagonists , Pineal gland -- Research
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:3745 , http://hdl.handle.net/10962/d1003223 , Calcium -- Antagonists , Pineal gland -- Research
  • Description: The calcium signal has emerged as an imponant component of intracellular regulation. Pineal function was thought to be slowed by the prominent calcification seen with increasing age, but recently it has been shown that calcium plays a crucial role in the adrenergic regulation of the gland. Beta-adrenoceptor stimulation increases melatonin (aMT) synthesis by increasing the activity of cyclic 3 '-5' adenosine mono phosphate (cAMP). Cyclic-AMP regulates the production of the pineal hormone, melatonin, from serotonin via the rate-limiting enzyme N-acetyltransferase (NAT). Increased intracellular cAMP is essential to the adrenergic induction of NAT. Noradrenaline(NA)also elevates pinealocyte cyclic guanosine monophosphate (cGMP). Adrenergic regulation of these cyclic nucleotides involves both α₁ - and β-adrenoceptors. Beta-adrenoceptor stimulation is an absolute requirement. Alphal-adrenoceptor activation, which is ineffective alone, serves to amplify the β-stimulated cAMP and cGMP responses via a positive effect on a Ca²⁺⁻/ phospholipiddependent protein kinase (Protein kinase-C) and a net influx of Ca²⁺ into the pinealocyte. Previous studies suggest the use of organic calcium channel blockers (CCBs) as probes of calcium-mediated processes. Applying this concept, the study set out to investigate the influence of a representative of each of the structurally diverse groups of calcium channel blockers viz. verapamil, diltiazem and nifedipine, and to examine their effect on β-adrenoceptor stimulation. It used the β-agonist isoprenaline (ISO) and the mixed [α₁/β]agonist noradrenaline (NA), for its combined [α₁/β]adrenoceptor stimulation, on agonist-induced increases in the production of radio-labelled aMT and N-acetylserotonin(aHT) -measured as the sum of N-acetylated product- from [¹⁴C] serotonin. This was done using organ cultures of rat pineal glands. It was speciously assumed that this drug paradigm would allow the determination of Ca²⁺ influx and/or the blocking thereof in the reported potentiation by using ISO as a non Ca²⁺ -entry stimulating agonist, compared with NA and its Ca²⁺ -entry stimulating properties. Surprisingly, all 3 CCB's potentiated the effect of NA. Only diltiazem was found not to potentiate the effect of ISO. In an attempt to uncover the reason for these results, the study moved toward a mechanistic approach,focusing in an antecedent manner on the various steps in the indole metabolic pathway to identify the point at which the change occurred, and hence possibly elucidate the mechanism responsible for the paradoxical increase. Experiments which assayed the levels of NAT, under the same drug conditions, showed the paradoxical increase to be already evident at this stage. Secondary experiments confirmed that NA stimulation of the pineal is dependent on Ca²⁺, both in organ culture and with NAT: the Ca²⁺ chelator EGTA abolished adrenergically-induced stimulation, while Ca²⁺ added after EGTA, restored the enzyme activity. The ionophore A23187 (which is able to transport Ca²⁺ directly into the pinealocyte via a mechanism which differs from the α₁ - mechanism) when used in conjunction with ISO or NA, was able to potentiate the responses of these two agonists relative to control values (agonist-alone), but by itself had no effect. With the enzyme NAT critically dependent upon cAMP for its induction, it was decided to determine the levels of cAMP and then those of its regulator, cAMP-phosphodiesterase (cAMP-PDE). This reasoning was prompted by reports of anti-calmodulin activity shown by the CCBs, in addition to their channel blocking effects. By binding to calmodulin (CaM), the CCBs are reportedly able to inhibit the CaM-dependent activation of cAMP-PDE. Following NA stimulation, verapamil caused a significant decrease in cAMP-PDE levels and an increase in cAMP. The other CCBs showed a similar trend. Glands stimulated with ISO in the presence of verapamil and nifedipine showed no significant differences in cAMP or cAMP-PDE levels. Diltiazem, however, was found to decrease the effect of ISO on cAMP while causing a concomitant increase in cAMP-PDE. This i) supported a possible hypothesis that the observed enhancement is a result of cAMP levels remaining elevated due to an inhibition of cAMP-PDE by the CCEs and ii) pointed to the possible presence of a CaM-sensitive PDE within the rat pineal gland. To test this hypothesis, two drugs which are more specific in their actions on CaM effects were chosen to see if the earlier results could be mimicked and thereby confirmed. Glands stimulated with NA in the presence of the specific CaM inhibitor R 24571 showed increased NAT activity and [¹⁴C]-aMT production. cAMP-PDE levels were clearly down, thus corroborating the possibility of cAMP-PDE inhibition. Glands incubated in the presence of M&B 22948, a CaM-sensitive PDE inhibitor, showed similar increases in NAT activity and [¹⁴C]-aMT. These findings therefore support the initial results and although indirect, confirm the hypothesis that the paradoxical increase following predominantly NA stimulation could be a result of cAMP levels remaining elevated, due to inhibition by the CCEs of the CaM-dependent activation of its regulator cAMP-PDE. In summary, data presented herein concur with proposals that: i) the CCEs are not specific enough to be used as tools to research Ca²⁺ -mediated events, as they appear to have sites of action other than the voltage operated channel (VOC); eg. binding to calmodulin, ii) there are functional differences between the CCEs as shown by diltiazem in this series of experiments, iii) there is a CaM-sensitive-PDE present in the pineal.
  • Full Text:
  • Date Issued: 1992

A classroom-based investigation into the potential of the computer spreadsheet as a learning tool within the secondary school mathematics curriculum

  • Authors: Funnell, Lynette
  • Date: 1992
  • Subjects: Mathematics -- Computer-assisted instruction Mathematics -- Study and teaching (Secondary) Electronic spreadsheets
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1448 , http://hdl.handle.net/10962/d1003329
  • Description: The influence of modern technology on education is becoming more noticeable and has implications for the curriculum and the teaching methods of mathematics. The microcomputer can be used effectively as a powerful teaching and learning aid within the mathematics classroom. This study considers the role of the computer as an aid to teachers and pupils in the teaching and learning of mathematics and shows it as having great potential. At present relatively few schools in South Africa are using the computer as a teaching aid in the mathematics classroom. The researcher proposes that some reasons are a shortage of suitable programs, the fact that few teachers have adequate skills in educative uses of the computer and most teachers are not skilled in programming techniques. Based on this assessment of the problem, spreadsheet programs related to some mathematics lessons, together with teaching notes and pupils' material have been developed. Besides describing the potential of the computer in mathematics, this study outlines the development of three spreadsheet packages and suitable teaching methodologies used for each package, and assesses an action research investigation undertaken by the researcher, teachers and pupils when using these spreadsheet packages in six classes. The findings of the investigation are most encouraging. The overall conclusion is that computer spreadsheet packages can assist the teacher in making the learning of mathematics more effective, more interesting and more enjoyable.
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  • Date Issued: 1992

Inkciyo yengwemesha

  • Date: 1954-07-01 , 2023-09-01
  • Subjects: Beadwork , Genital girdle
  • Language: English
  • Type: realia , personal adornment
  • Identifier: http://hdl.handle.net/11260/8309 , vital:67691
  • Description: A genital girdle with brass washers in which the bead apron is supported at the back by two rows of very small brass washers strung on plaited cloth threads, worn by a girl of 12 or more years, It is part of Walter Sisulu University Beadwork Collection that was acquired from Mrs Broster in 1992. , Purchased from Mrs Joan Broster , Forms part of: Walter Sisulu University Beadwork Collection
  • Full Text: false
  • Date Issued: 1954-07-01

Up Beat Issue Number 7 1992

  • Authors: SACHED
  • Date: 1992
  • Subjects: SACHED
  • Language: English
  • Type: text
  • Identifier: http://hdl.handle.net/10962/116493 , vital:34392
  • Description: Life often doesn’t turn out as you had hoped. The world isn’t always a fair place. Some teenagers I know, just accept their lot. Others work hard to make even small dreams come true. This issue is full of stories about young people. They are not pop stars, famous TV heroes or powerful leaders. They are ordinary people like you and me. But they have something in common. They are all determined to make something of their lives. Meet Patrick from Uitenhage, he’s a basketball player who’s off to Japan. Meet Nomnikelo, at 23 she’s a domestic worker. But she’s determined to become a nurse. There’s Lucky. He was forced to leave school in Std 4. He couldn’t find a job, but now he’s making money from scraps. Meet Lerata, she never believed in love. Then one day after a school debate. You’ll find stories about teenagers overseas too. Read about Hodan, Emadul and Van Lac. They are all struggling to start a new life in London. When we read about Lucky, Nomnikelo or Lerata, we can learn something. We admire the way they have got on with it, faced new challenges. But we can also learn from them - about ourselves. We all have it in us, to change our world and make the most of our lives. Enjoy reading!
  • Full Text:
  • Date Issued: 1992

Selecting educational computer software and evaluating its use, with special reference to biology education

  • Authors: Beyers, Ronald Noel
  • Date: 1992
  • Subjects: Biology -- Study and teaching -- Computer programs Education -- Data processing Biology -- Computer-assisted instruction
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1764 , http://hdl.handle.net/10962/d1003649
  • Description: In the field of Biology there is a reasonable amount of software available for educational use but in the researcher's experience there are few teachers who take the computer into the classroom/laboratory, Teachers will make use of video machines and tape recorders quite happily, but a computer is a piece of apparatus which they are not prepared to use in the classroom/laboratory. This thesis is an attempt to devise an educational package, consisting of a Selection Form and an Evaluation Form, which can be used by teachers to select and evaluate educational software in the field of Biology. The forms were designed specifically for teachers to use in preparation of a computer lesson. The evaluation package also provides the teacher with a means of identifying whether the lesson has achieved its objectives or not. The teacher may also be provided with feedback about the lesson. The data is gathered by means of a questionnaire which the pupils complete. It would appear that teachers are uncertain as regards the purchase of software for their subject from the many catalogues that are available. The evaluation package implemented in this research can be regarded as the beginnings of a data base for the accumulation of information to assist teachers with details on which software to select. Evidence is provided in this thesis for the practical application of the Selection and Evaluation Forms, using Biology software.
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  • Date Issued: 1992

Facies mapping of the Vaal Reef placer as an aid to remnant pillar extraction and stope width optimisation

  • Authors: O'Donovan, Anthony Gareth
  • Date: 1992
  • Subjects: Facies (Geology) -- South Africa -- Vaal Reef placer
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4947 , http://hdl.handle.net/10962/d1005559 , Facies (Geology) -- South Africa -- Vaal Reef placer
  • Description: The Vaal Reef placer is situated on the unconformable junction of the Strathmore and Stilfontein formations of the Johannesburg Subgroup. Within the South Division of the Vaal Reefs Exploration and Mining company lease, the Vaal Reef Placer is shown to be composed of several different units. Each unit exhibits its own specific characteristics and trend direction which can be used to establish distinct "Reef packages". These packages can be mapped in such a way as to provide a preliminary lithofacies map for the Vaal Reef Placer. The delineation of such geologically homogenous zones, and the development of a suitable depositional model, can be utilised in several ways. The characteristics of a particular zone are shown to influence the control of stoping width, evaluation of remnant pillars and the geostatistical methodology of evaluating current and future ore reserve blocks.
  • Full Text:
  • Date Issued: 1992
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