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The development and evaluation of a Nd:YAG laser incorporating an unstable resonator

- De Kock, Trevor Neil

  • Authors: De Kock, Trevor Neil
  • Date: 1986
  • Subjects: Nd-YAG lasers , Lasers -- Resonators , Laser beams
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5512 , http://hdl.handle.net/10962/d1008566 , Nd-YAG lasers , Lasers -- Resonators , Laser beams
  • Description: Introduction: For approximately the last eight years the Laser Section of the National Physical Research Laboratory (NPRL) has been interested in inter alia, pulsed solid-state lasers and in particular, Nd:YAG. Investigations of various resonator types were undertaken with a view to the improvement of the laser parameters such as output energy, pulse width, beam quality and sensitivity to mirror misalignment. In 1980 a Nd: YAG laser employing a rotating prism Q-switch was constructed (Preussler (1980)). It involves rotating one of the two cavity reflectors so that they are parallel for only a brief instant in time. Typically the prism must rotate at a speed of 20 000 r.p.m. to ensure a single pulse output. Such lasers suffer from the tendency to emit multiple pulses, they are very noisy and they require frequent maintenance because of the short lifetime of the bearings. A resonator employing conventional curved mirrors and an electro-optical Q-switch was constructed in 1980 (Robertson & Preussler (1982)). In 1981 an electro-optically Q-swi tched laser making use of a crossed Porro-prism resonator was investigated due to its relative insensitivity to misalignment of the reflectors compared with the conventional mirror resonator (Nortier (1981)). Improvements in terms of output power, beam divergence and beam quality can be achieved by making use of a so-called unstable resonator. Such a laser has been investigated and is reported on in this study. Chapter 2 provides some background into laser theory and operation while chapter 3 deals with the theory of the unstable resonator. Chapter 4 provides details of the experimental equipment and techniques used in the work and chapter 5 discusses the evaluation of the project and results obtained.
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  • Date Issued: 1986

The development of the meaning of non-ostensive words in a group of primary school children

- Segal, Denise Erica

  • Authors: Segal, Denise Erica
  • Date: 1986
  • Subjects: Connotation (Linguistics) , Children -- Language , Language acquisition
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:2372 , http://hdl.handle.net/10962/d1004917 , Connotation (Linguistics) , Children -- Language , Language acquisition
  • Description: The purpose of the present study was to investigate word meaning and its development in primary school children (6-12 years) . It was argued that the learning and development of the meanings of words such as pain cannot be primarily explained by means of ostensive definition. Furthermore, existing theories of word meaning which deal predominantly with substantive words fail to account for the learning of non-ostensive words. The pertinent psychological, linguistic and developmental psycholinguistic approaches to word meaning are reviewed briefly. The prototype approaches to word meaning are modified to apply to non-ostensive words . The focus is on conceptual meaning, that is, the way in which the senses of a word alter in different contexts. It is argued that the meaning of the word is its use in a diversity of linguistic contexts. The term "grammar" is applied in a unique way to encompass the meaning of the word (which stems in part from the words with which it co-occurs) as well as its selective use with other words in the language. Ninety-five metalinguistically-phrased tasks comprising short questions and picture-story sequences were analyzed in depth. The tasks were administered individually. A flexible interview afforded additional probing for each question. The analysis comprised percentage scores of responses at different age levels together with verbatim transcripts and qualitative descriptions: Uniformity, variation and developmental trends were found on different tasks for any particular word. Developmental trends were noted in children's understanding of particular words (for example, same), thereby extending the findings of previous researchers. There was evidence for a progression in children's ability to take into consideration that a word alters its sense according to the linguistic context in which it occurs (for example, same as it relates to chair versus dress versus pain). A comprehensive account of the words meaning could be established when a diversity of tasks was applied for each word. Children of different age levels employed different strategies in answering the questions posed. A model is proposed to describe the development of the meaning of non-ostensive words during the primary school years. It is suggested that psycholinguistic studies on word meaning be re-evaluated and that language and reading programmes incorporate the notion of "grammar". Application of this approach to the study of substantive word meaning in preschool children has important implications for theories of word meaning and for therapeutic intervention.
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  • Date Issued: 1986

The effect of the pesticide, endosulfan, on hepatic cytochrome P-450, liver and gill ultrastructure, and selected haematological parameters of Oreochromis Mossambicus (Peters, 1852) (Pisces : Cichlidae)

- Quick, Arthur Joseph Rex

  • Authors: Quick, Arthur Joseph Rex
  • Date: 1986
  • Subjects: Pesticides , Mozambique tilapia , Cichlids
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5195 , http://hdl.handle.net/10962/d1001971 , Pesticides , Mozambique tilapia , Cichlids
  • Description: Two possible ways in which fish may acclimate to prolonged exposure· to sublethal levels of endosulfan were investigated: induction of the hepatic monooxygenase system and changes in haematology. These studies also involved an examination of the ultrastructure of liver and gill tissue. Endosulfan caused none of the characteristic phenobarbital-type inductive effects on the liver of Oreochromis mossambicus. There was no increase in cytochrome P-450 levels, microsomal protein or hepatosomatic index. The reasons for the lack of induction are discussed. The effect of endosulfan on the following haematological parameters was determined: haemoglobin, erythrocyte count, microhaematocrit, mean erythrocyte volume and mean erythrocyte haemoglobin concentration. The only effect was an increase in erythrocyte count. The value of changes in haematological parameters as indicators of pollutioninduced anemia in the field is discussed. No changes in gill ultrastructure were noted although electron micrographs of liver tissue showed lesions in hepatocytes. The diagnostic value of pollution-induced pathological changes on cell ultrastructure are discussed. Recommendations are made with regard to future large scale application of pesticides on or near large water bodies
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  • Date Issued: 1986

The effects of inbreeding and laboratory-rearing on a pyraustid moth, Mimorista pulchellalis Dyar (Lepidoptera: pyraustidae), imported for the biological control of jointed cactus in South Africa

- Wright, Margaret Dorothy

  • Authors: Wright, Margaret Dorothy
  • Date: 1986
  • Subjects: Pyralidae -- South Africa , Cactus -- South Africa , Moths -- South Africa , Insect pests -- Biological control -- South Africa , Inbreeding
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5615 , http://hdl.handle.net/10962/d1003123 , Pyralidae -- South Africa , Cactus -- South Africa , Moths -- South Africa , Insect pests -- Biological control -- South Africa , Inbreeding
  • Description: Inbreeding was thought to be responsible for the loss in the second filial generation (F₂) of Amalafrida leithella Dyar, Cactoblastis mundelli Heinrich, Nanaia sp. Heinrich, Sigelgaita sp. Heinrich and Sigelgaita transilis Heinrich in the laboratory. This pre-empted the investigation of the effects of inbreeding on another cactophagous moth, Mimorista pulchellalis Dyar, an established biological control agent of jointed cactus in South Africa. Initially three populations were set up. A randomly-mating control (OUT 1) population, and a sibmating experimental (IN 1) population, consisted of laboratory-reared stock . A second experimental population (KR 1) comprised a small number of field-collected randomly-mating individuals which recreated the conditions under which the five abovementioned species were lost. The inbreeding depression of fifteen fitness components was assessed. The mean values of each component in each generation of treatments IN 1 and KR 1 were compared with those of OUT 1. In addition the mean values of IN 1 were regressed against the coefficients of inbreeding since inbreeding depression is linear with respect to the probability of two genes at any locus being homozygous through ancestry. The component egg viability was important because a reduction in OUT 1, IN 1 and KR 1 in the F₂ resulted from mated females producing no viable eggs. Duplicate treatments OUT 2, IN 2 and KR 2 were set up to confirm whether this was a general F₂ phenomenon. Assessment of the fitness components prevented a direct evaluation of the numbers of offspring produced. However a hypothetical estimate of population size and growth rate was made using the percentage survival calculated from life-table analysis. Although not statistically demonstrable in the component analysis, life table analysis indicated that egg viability suffered an inbreeding depression and affected population fitness. It was also evident that treatments OUT 1 and 2 were fitter than treatments IN 1 and 2 and KR 1 and 2 with respect to population fitness. Thus, inbreeding, resulting from sibmating and introduction of a small number of individuals to a laboratorYJ caused a decrease in numbers of offspring produced and population growth rate. This is important in relation to the demise of the cactophagous Lepidoptera and to future biological control programmes.
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  • Date Issued: 1986

The industrial development policy of Ciskei

- Black, Philip A, McCartan, Patrick John, Clayton, P M

  • Authors: Black, Philip A , McCartan, Patrick John , Clayton, P M
  • Date: 1986
  • Subjects: Ciskei Peoples Development Bank Manufactures -- South Africa -- Ciskei Industries -- South Africa -- Ciskei Ciskei (South Africa) -- Economic conditions Ciskei (South Africa) -- Economic policy
  • Language: English
  • Type: Book , Text
  • Identifier: http://hdl.handle.net/10962/2083 , vital:20254 , ISBN 0868101451
  • Description: There can be little doubt that manufacturing industry is one of the principal vehicles in the process of economic growth and development. The effect of growth in output and employment in this sector usually stimulates other sectors making for an expansion of output and employment opportunities across an entire economy. This paper is thus concerned with the development of manufacturing industry in Ciskei over the past decade as well as its prospects for growth in the foreseeable future. The paper itself falls into five sections. Section 1 provides a brief historical overview of political and constitutional developments and of industrial growth in the Border region and in Ciskei ever the past fifteen years. Section 2 outlines the current incentive package and indicates its impact on the industrial sector of Ciskei. Section 3 considers the recommendations of the Swart Commission while Section 4 discusses the role and activities of the Ciskei People's Development Bank. Section 5 presents the findings of a limited survey of manufacturing firms in Ciskei and leads onto the final section which offers some recommendations for industrial development in Ciskei specifically and in Region D as a whole. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
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  • Date Issued: 1986

The life and work of Robert Paul

- Johnson, Christopher Charles Bonsall

  • Authors: Johnson, Christopher Charles Bonsall
  • Date: 1986
  • Subjects: Paul, Robert, 1906-1980 , Artists -- Zimbabwe
  • Language: English
  • Type: Thesis , Masters , MFA
  • Identifier: vital:2510 , http://hdl.handle.net/10962/d1018631
  • Description: [From Introduction] When Robert Paul died in 1980, his daughter Colette Wiles gave her father's art materials to an artist who was very close to both Robert and his wife in their last years - Dian Wright. The materials consisted of five different pigments and brushes cut into different shapes to suit the artist. This is remarkable when one considers his proficiency in a variety of media and his accurate portrayal in the far reaching studies he executed of the Zimbabwean landscape. Yet, it is characteristic of his resourcefulness that Paul could make 'something out of nothing'. Paul welcomed the opportunity of new landscape when he arrived in Rhodesia in 1927. Against the backdrop of a chosen isolation from the British Isles, Paul developed his own personal tracks in spite of any early influence through John Piper with the English Southern Landscape idioms of the 1920s. This was a fruitful isolation where the creation of his art retained influences but were manipulated according to his needs and unleashed with a proficiency sometimes equal to his peers, who later found fame under the term 'Neo-Romantics'. Paul remained an individual in Africa. My intention in this essay is three-fold; first, to illustrate the effects and influences of 'chosen' and 'enforced ' isolation on his work. Secondly, I wish to determine the extent of the influence that Piper and the Neo-Romantics had on Paul and to illustrate mostly with anecdotes his life and life-style. He was no mean character. His life-long obsessions with art, alcohol and women were played out with a flair and dry humour which few emulated in his era. Although a strictly academic approach can be applied to the assessment of his work, his life followed thoroughly unorthodox lines. As Bradshaw noted when he wrote the forward to the Catalogue of Paul's Retrospective in 1976, he (Paul) had no historical interests in the accepted sense of the word. , ABBYY FineReader 12
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  • Date Issued: 1986

The machine and painting: an investigation into the interrelationship(s) between technology and painting since 1945

- Hennig, Sybille

  • Authors: Hennig, Sybille
  • Date: 1986
  • Subjects: Art and technology Art, Modern -- 20th century -- History
  • Language: English
  • Type: Thesis , Masters , MFA
  • Identifier: vital:2468 , http://hdl.handle.net/10962/d1009435
  • Description: Introduction: We, i.e. contemporary Western man, live in a society which has increasingly embraced Science and Technology as the ultimum bonum. The Machine, i.e. Science and Technology, has come to be seen as an impersonal force, a New God - omniscient, omnipotent: to be worshipped and, alas, also to be feared. This mythologem has come to pervade almost every sphere of our lives in a paradigmatic way to the extent where it is hardly ever recognized for what it is and hence fails to arouse the concern it merits. While some of the more perceptive minds - such as Erich Fromm, Rufino Tamayo, Carl Gustav Jung, Konrad Lorenz and Arthur Koestler, to mention but a few - have started ringing the alarm bells, the vast majority of our species seem to plunge ahead with their blinkers firmly in place (more or less contented as long as they can persude themselves that these blinkers were manufactured according to latest technological and scientific specifications). Man’s uniquely human powers - his creative intuition, his feelings, his moral and ethical potential, have become sadly neglected and mistrusted. Homo sapiens – “homo maniacus” as Koestler suggests? - is now at a crossroads: he has reached a point where the next step could be the last step and result in the annihilation of man as a species. Alternately, avoiding that, there is the outwardly less drastic but essentially equally alarming possibility of men becoming robots, while a third alternative has yet to be found. While it does appear as if a lot of young people, noticeably among students, have started reacting against the over mechanization of life, these reactions often tend to follow the swing-of-the-pendulum principle and veer towards the other extreme, throwing out the baby with the bathwater and falling prey to freak-out cults in a kind of mass-irrationalism, rejecting science and technology altogether. Artists who by their very nature perhaps are particularly sensitive - in a kind of seismographic way - to the currents and undercurrents of their age, have become aware of the effects of science and technology on our way of living, and many of them have in one way or another taken a stand in relation to the position of man in our highly technological world. Looking at the art produced over the last four decades, it is truly astonishing to what extent our changed world reflects in our art - a world and a Weltbild very different from that of our ancestors even just a few generations ago. The purpose of the present study is to survey some of the observations and commentaries that painters and certain kindred spirits from the sciences over the last few decades have offered, in the hope of, if not answering, at least defining and posing anew some of the questions that confront us with ever-increasing urgency.
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  • Date Issued: 1986

The manipulated photographic images of Man Ray and Moholy-Nagy: "a deconstructural approach"

- Fry, Roger Bruce

  • Authors: Fry, Roger Bruce
  • Date: 1986
  • Subjects: Man Ray, 1890-1976 Moholy-Nagy, László, 1895-1946 Photography, Artistic
  • Language: English
  • Type: Thesis , Masters , MFA
  • Identifier: vital:2470 , http://hdl.handle.net/10962/d1009447
  • Description: From introduction: In the following essay an emphasis has been placed on manipulated photographic images. Although this implies a whole variety of ways in which these images can be manipulated e.g. in collage, silkscreen etc., the emphasis here is on images that have a fabricated or deliberate manipulation of subject matter to make up the photograph.
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  • Date Issued: 1986

The role of the guidance teacher in preparing young people for personal and social life in Gazankulu

- Machimana, Albert

  • Authors: Machimana, Albert
  • Date: 1986
  • Subjects: Counselling , Guidance , Life skills , Secondary education , Self concept , Gazankulu
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1381 , http://hdl.handle.net/10962/d1001447
  • Description: In the modernising South African society, young people are faced with personal and social problems which make it very difficult for them to adjust positively to life in general. In the end they are frustrated in many situations in life because of their inability to cope with these problems. One of the major problems that the Blacks in South Africa are faced with is that of a poor self-concept. This is a major problem because any adjustment and behaviour in life is, to a large extent, influenced by the self-concept of the individual. This thesis aims at focusing attention on those social issues which play a major role in the development of the self-concept and the lives in general, of Black people in Gazankulu. It is also concerned with the role of the guidance teacher in preparing young people for a more satisfying life (Introduction, p. 1)
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  • Date Issued: 1986

The Role of the Missionaries in Conquest

  • Date: 1986
  • Subjects: South Africa -- History -- 20th century , Government, Resistance to -- South Africa
  • Language: English
  • Type: text , book
  • Identifier: http://hdl.handle.net/10948/37293 , vital:34154 , Bulk File 7
  • Description: This is one of many individual publications put out by the New Unity Movement History Series and is a republication of a book by Nosipho Majeke.
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  • Date Issued: 1986

Theme in conversational discourse : problems experienced by speakers of Black South African English, with particular reference to the role of prosody in conversational synchrony

- Gennrich-de Lisle, Daniela

  • Authors: Gennrich-de Lisle, Daniela
  • Date: 1986
  • Subjects: English language -- Spoken English -- Foreign speakers , Black English -- South Africa
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2370 , http://hdl.handle.net/10962/d1004512
  • Description: This study is an investigation of instances of conversational failure in interaction as evidenced by speakers of Black South African English (BSAE) , with a particular focus on the role of prosody in conversational (a)synchrony. The data analysed consist of six conversations, one SAE-SAE (South African English) encounter, four BSAE- SAE encounters and one BSAE- BSAE encounter. After a theoretical framework is set up, the analysis is conducted by means of two triangulation research processes based on Ethnomethodology. The analysis consists of an investigation into selected extracts which participants and informants alike perceived as 'stressful'. An attempt is made to isolate the sources of each instance of pragmatic failure. Prosodic features are found to be important in establishing and maintaining theme and conversational synchrony. But other factors are also involved. The analysis reveals two major influences of asynchrony: deviance in the use of (in order of importance) prosodic, lexical and syntactic cues to discourse functions; and a mismatch in the application of socio-cultural principles guiding conversational behaviour. The study leads into a brief outline of aims, objectives and conversational competence at a tertiary level and concludes with suggestions for further research.
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  • Date Issued: 1986

Thina Singabantwana

- St. Bedes Theological Students, Poswayo, M., Reverand, Dargie, Dave

Thuma mina

- Church Choir, Composer not specified, Dargie, Dave

Thuma mina

- St. Bedes Theological Students, Composer not specified, Dargie, Dave

Title Not Specified

- Group of Local Women, Composer Not Specified, Dargie, Dave

Title Not Specified

- St Bedi's Church Choir, Composer not specified, Dargie, Dave

Title Not Specified

- Zionist Group, Composer not specified, Dargie, Dave

Title Not Specified

- Dyiwili, Nofinishi, Group of Men and Women, Composer not specified, Dargie, Dave

Title Not Specified

- Dyiwili, Nofinishi, Composer not specified, Dargie, Dave

Title Not Specified

- Dyiwili, Nofinishi, Group of Men and Women, Composer not specified, Dargie, Dave

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