Preliminary geochemical data for dolerite dykes and sills of the southern part of the Etendeka Igneous Province
- Authors: Marsh, Julian S , Erlank, Anthony J , Duncan, Andrew R
- Date: 1991
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/132133 , vital:36803
- Description: Over the last 15 years systematic geochemical and petrological investigation of the igneous rocks of the Early Cretaceous - Late Jurassic Etendeka Igneous Province of northwestern Namibia have focused on the tholeiitic basaltic lavas and interbedded silicic volcanic rocks and the large central subvolcanic complexes of Brandberg, Erongo, Okenyenya, Messum, Doros and Cape Cross. Previously these rocks were grouped into the Karoo Volcanic Province of South Africa, but in view of the distinct age difference between the igneous rocks of the Etendeka region and Karoo rocks occurring elsewhere in southern Africa , we propose to regard them as constituting a separate Etendeka Igneous Province which exhibits a close lithological, geochemical and temporal correlation with the Parana Flood Basalt Province of South America.
- Full Text:
- Date Issued: 1991
Racial segregation in East London, 1836-1948
- Authors: Nel, Etienne L
- Date: 1991
- Language: English
- Type: Article
- Identifier: vital:6717 , http://hdl.handle.net/10962/d1006790
- Description: Urban racial segregation in East London has a distinctive heritage, making the city one of South Africa's most segregated in the pre-Union era. Segregation was initiated by the British military in the then colony of British Kaffraria, and was later enhanced by successive municipal councils. Municipal ordinances ensured exceptionally high levels of segregation in the city during the 19th century. The enforcement of Asian segregation in this era is noteworthy. Urban planning in the 20th century resulted as much from local as national considerations and legislation. Segregation was a reality in East London prior to the passage of the Group Areas Act. The deteriorating social circumstances in the long-segregated African areas in particular receive special mention, as do government attempts to rectify the situation through the institution of state commissions.
- Full Text: false
- Date Issued: 1991
Rates of return to education of blacks in South Africa
- Authors: Serumaga-Zake, Philip A
- Date: 1991
- Subjects: Black people -- Education -- South Africa -- Statistics Black people -- Employment -- South Africa -- Statistics Black people -- South Africa -- Economic conditions -- Statistics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5565 , http://hdl.handle.net/10962/d1002084
- Description: The principal objectives of this empirical study were to test the hypothesis that eduction is a major determinant of people's earnings differentials and to calculate private and social rates of return to education of blacks in South Africa excluding Transkei, Bophuthatswana, Venda and Ciskei. Basically, the data for working men and women used in the study were extracted from the 1985 current Population survey files comprising a sample representative of the black population. Lifetime earnings profiles are constructed from these data for five educational levels, namely, no schooling up to standard 1, standards 2 to 4, standards 5 to 7, standards 8 to 9 and standard 10. Schooling is assumed to account for 60% of the income differentials between these profiles, after adjustment for the differing probabilities of finding work of persons in specific age-education groups. Imputed average household outlays on schooling are taken as the private direct cost of education supplemented by estimates of per pupil spending by the various government departments responsible for black schooling for calculation of the social costs per year of primary and secondary schooling. Indirect cost in the form of imputed foregone earnings are included from standard 5 (age 15) onwards. The resulting private internal rates of return to education of males are about 16% at primary level and 24% for secondary schooling. Corresponding social rates of return are about 6% for primary and 15% for secondary education. The estimates for females indicate that between no schooling and standards 2 to 4 level, the private and social rates of return are -1% and -4% respectively, from standards 2 to 4 to standards 5 to 7 level, private returns of 12% and social returns of 4% are reported and for the remaining secondary school phases private returns of 32% and social returns of 15% are estimated. It is implied that black education is receiving minimal government financial assistance compared to those of the other population groups. The evidence of the results of the study indicates that; besides education, marital status, locational, regional and occupational variables also influence earnings differentials, the governments responsible for black education should emphasize human capital investment in relation to physical capital investment, on average more educated persons are better off than the less educated ones and with the exception of female early primary schooling, generally, it is worthwhile for an individual to undertake a certain educational programme investment
- Full Text:
- Date Issued: 1991
Rhodes Newsletter
- Date: 1991-Dec
- Subjects: Grahamstown -- Newspapers , Journalism -- South Africa , Rhodes University -- Newspapers , Rhodes University -- Rhodes Newsletter
- Language: English
- Type: Text
- Identifier: vital:14308 , http://hdl.handle.net/10962/d1019013
- Description: The Old Rhodian Union Newsletter keeping in contact with Alumni and informing them of the latest news from Rhodes University. The publication ran from 1951 to 2001, and was subsequenlty replaced with an electronic newsletter distributed via electronic mail.
- Full Text:
- Date Issued: 1991-Dec
Rhodes University Annual Report 1991
- Authors: Rhodes University
- Date: 1991
- Subjects: Rhodes University -- history Rhodes University -- employees Rhodes University -- students
- Language: English
- Identifier: vital:20039
- Full Text:
- Date Issued: 1991
Rhodes University Graduation Ceremony 1991
- Authors: Rhodes University
- Date: 1991
- Subjects: Relly, Gavin Walter Hamilton
- Language: English
- Type: text
- Identifier: vital:8125 , http://hdl.handle.net/10962/d1006750 , Relly, Gavin Walter Hamilton
- Description: Rhodes University Graduation Ceremonies Friday, 12 April 1991 at 8 p.m. [and] Saturday, 13 April 1991 at 10 a.m. in the 1820 Settlers National Monument. , Rhodes University East London Graduation Ceremony Saturday, 18 May 1991 at 10.00 a.m. in the Guild Theatre. , The Installation of Gavin Walter Hamilton Relly as Chancellor of Rhodes University to be followed by a Graduation Ceremony Friday, 12 April 1991 at 10 a.m. in the 1820 Settlers National Monument.
- Full Text:
- Date Issued: 1991
Rites of passage: Substance dependence and the negotiation of development tasks - a case study
- Authors: Roux, Catharina
- Date: 1991
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/193242 , vital:45313
- Description: This thesis is an attempt to provide an understanding of drug addiction in its relation to the tasks and arrests which take place during the developmental process. Current theories of drug addiction are situated within the parameters of developmental theory; Object Relations Theory, Lacanian Structuralism and Freud’s concept of the Oedipus Complex are drawn on. The dual regressive and progressive function of drugs as it relates to developmental tasks and arrests is illustrated, the argument being that a very specific relationship exists between the compulsive use of drugs and the developmental tasks which need to be avoided as well as those which need to be negotiated. The case study research method is made use of in the attempt to illustrate the links between drug addiction and specific developmental tasks. I present an in-depth analysis of the developmental history of Rafiq Jaffer, an inpatient at the drug unit at Lentegeur Psychiatric Hospital, drawing on the material which was collected during nine months of individual therapy. As Borderline Personality Disorder is the primary diagnosis in the case of Rafiq Jaffer, the emphasis is by necessity put on borderline pathology. The primary aim of the thesis is, however, to highlight the need to understand the compulsive use of drugs within the context of the developmental process, thereby developing a conceptualisation against which further cases may be tested. , Thesis (MA) -- Faculty of Humanities, Psychology, 1991
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- Date Issued: 1991
ROB report to the COSATU Western Cape Regional Congress
- Authors: COSATU
- Date: Mar 1991
- Subjects: COSATU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/135365 , vital:37261
- Description: In this report we have focused more on policy issues than on an assessment of problems in the region, as we need to use our Regional Congresses in preparation for the issues which will be debated at National Congress. The government and the bosses are also trying to stop us making further gains. How do we respond? STATE OF THE NATION In the past year, a number of gains have been made by COSATU, some demands have been won, but many new areas of struggle have opened up. In the past year, a number of gains have been made by COSATU, some demands have been won, but many new areas of struggle have opened up. In October 1990, the SCN accord was signed, which gave us back the old Unfair Labour Practice definition, and also set the scene for introducing new legislation for farm, domestic and public sector workers. Since then, a number of unions have been meeting with sub-committees of the National Manpower Commission as well as the Commision for Administration (CFA) to argue for basic rights and legislation for these workers. COSATU now has a national Public Sector Forum under the COSATU Organising Department, and we are gearing up for this struggle as well as the struggle for an entirely and progressive Labour Relations Act.
- Full Text:
- Date Issued: Mar 1991
SADTU the Biggest Teachers’ Organisation in South Africa
- Authors: SADTU
- Date: Oct 1991
- Subjects: SADTU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/134695 , vital:37191
- Description: During the past 12 months the South African Democratic Teachers’ Union (SADTU) recruited 37 947 teachers to the union, making SADTU the biggest union in South Africa today. With completed membership forms in excess of 15 000 still to be collected, SADTU can talk of an effective membership of 50 000 teachers, the SADTU president, Shepherd Mdladlana said during his address to Congress at Nasrec, Johannesburg. The SADTU membership further consists of teachers from all departments all over the country, making SADTU the only unitary, non-racial teachers’ union in the country. In his report to Congress, SADTU General Secretary, Randall van den Heever, pointed out that the most progressive members of all erstwhile organisations - newly emergent as well as established - occupied leadership positions within the union’s branch and regional structures, making SADTU the most well represented union of teachers from all sectors.
- Full Text:
- Date Issued: Oct 1991
Sir Godfrey Lagden : colonial administrator
- Authors: Burton, David Raymond
- Date: 1991
- Subjects: Lagden, Godfrey Yeatman, Sir, 1851-1934 South Africa -- History -- 1836-1909
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2519 , http://hdl.handle.net/10962/d1001848
- Description: The thesis attempts to provide a chronological analysis of Lagden's colonial career between 1877 and 1907. The youngest son of a parish priest, Lagden received limited formal education and no military training. By a fortuitous set of circumstances, he was able, as a man on the spot, to attain high ranking posts in colonial administration. As a young man, he acquired considerable experience in the Transvaal, Egypt and the Gold Coast. However, blatant disobedience led to his dismissal from Colonial service. Fortunately for Lagden, Marshal Clarke, newly appointed Resident Commissioner of Basutoland, insisted on Lagden being appointed to his staff. Except for a brief stint in Swaziland, Lagden remained in Basutoland until 1900. With Clarke, Lagden played a prominent role in the implementation of the Imperial policy of securing the support of the Koena chiefs by allowing them to retain and consolidate their power and influence. Lagden became Resident Commissioner in Basutoland when Clarke was transferred to Zululand. He continued established policies and championed the Basotho cause by opposing the opening of Basutoland to prospectors and by stressing the industrious habits of the Basotho. His tactful and energetic handling of the rinderpest crisis reduced dramatic repercussions amongst the Basotho and enabled cooperative Koena chiefs to increase their economic and political leverage. Despite his reservations over Basotho loyalty, Lagden emerged from the South African War with an enhanced reputation as the Basotho remained loyal and energetically participated in the Imperial war effort. Largely because of his Basutoland experience, Lagden was appointed the Transvaal Commissioner of Native Affairs in 1901. He was responsible for regulating African labour supplies for the mines and delineation of African locations. His failure to procure sufficient labour and his defence of African rights earned Lagden much abusive settler condemnation. As chairman of the South African Native Affairs Commission, Lagden produced an uninspiring report conditioned by the labour shortage and his personal distaste for decisive action. Nevertheless, its advocacy of political and territorial segregation influenced successive Union governments.
- Full Text:
- Date Issued: 1991
South African anti-apartheid documentaries 1977-1987: some theoretical excursions
- Authors: Steenveld, Lynette Noreen
- Date: 1991
- Subjects: Documentary films -- South Africa -- History and criticism , Apartheid -- South Africa , Anti-apartheid movements -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3484 , http://hdl.handle.net/10962/d1002939 , Documentary films -- South Africa -- History and criticism , Apartheid -- South Africa , Anti-apartheid movements -- South Africa
- Description: This study examines anti-apartheid documentary production in South Africa between 1977 and 1987. These documentaries were produced by a variety of producers in order to record aspects of South Africa's contemporary social history, and as a means of contributing - in some way - to changing the conditions described. While the 'content' of the documentaries is historical and social, and their intention political, this study is aimed at elucidating how a documentary, as a representational system, produces meaning. The study is therefore located within the discourse of film studies. My study is based on the theory that a documentary is the embodiment of several relationships: the relationship between social reality and documentary producers; the social relationships engaged in, in the production of the text; the relationship between the text and its audience 1, and the relationship between the audience and its social context. This informs my methodological approach in which analysis appropriate to each area of study is used. Using secondary sources obtained through standard library research, I pursue social and historical analysis of the 1970s and 1980s in order to contextualise both the producers of the documentaries, and their audience. The social relations of production of a text are examined using material gathered through extensive interviews with the producers and published secondary material. How this impinges on the documentary is ascertained through detailed textual analysis of 30 documentaries. For analytical clarity each chapter focuses on a specific aspect of documentary - although I do show how the various relationships impinge on each other. This research finds that the documentaries faithfully reflect the anti-apartheid ideology dominant in the extra-parliamentary opposition in the period under discussion - to the extent that all forms of consciousness are framed by this discourse. An examination of the textual strategies used shows that they are bound by the conventions of broadcast television. They therefore construct a spectator-text relationship which is not consistent with the political concern that democratic relationships be established as the basis of a post-apartheid society. In other words, there is an inconsistency between the ideology espoused, and the way in which film- and videomakers, in their specialised field of production, practise their politics. This can be attributed to the over-riding political intention of the documentarists 'to record' what is happening, and to establish a popular archive which can be used by extra-parliamentary opposition groups in their struggle against apartheid.
- Full Text:
- Date Issued: 1991
Southern Africa perspective - In South Africa: The Bloody Campaign Against Organized Labor
- Authors: COSATU
- Date: 1991
- Subjects: COSATU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/169033 , vital:41677
- Description: A year after African National Congress leader Nelson Mandela’s release from prison, South Africa’s Black trade unions, particularly the million-member Congress of South African Trade Unions (COSATU), remain at the heart of the movement for political democracy and economic and social change. Union activists have been instrumental in revitalizing mass opposition to apartheid — launching ANC branches, organizing local consumer and utility boycotts, and leading strikes over wages, job security and workplace racism that cost the white-run economy over four million work days during 1990. But labor’s role in the struggle for political and economic democracy has increasingly made the unions the target of state-sponsored political violence. Black labor’s resistance to oppression goes back to the 1920s, when the militant Industrial and Commercial Workers Union built a national membership of over 100,000. But it was not until 1981, after a wave of illegal strikes forced the apartheid regime to lift the ban on Black unions, that labor began to emerge as a major anti-apartheid force. With Mandela’s African National Congress and other organizations still outlawed, Black workers increasingly saw their unions as a vehicle for their political aspirations.
- Full Text:
- Date Issued: 1991
SPREAD-IT Sached Library Bulletin. Some tell, some hear, some judge news - some make it.
- Authors: SACHED
- Date: 1991
- Subjects: SACHED
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/173834 , vital:42414
- Description: The response to the first issue of SPREAD-IT was encouraging - to say the least. Not only did we find people reading it during centre staff meetings and during NCC debates, but we believe it has set a trend - the NWC is now also compliling a bulletin of news! Well, our spreading function is certainly becoming infectious - which, of course, was our intention. We even ran out of copies.
- Full Text:
- Date Issued: 1991
Stop privatisation - Join the campaign
- Authors: COSATU
- Date: June 1991
- Subjects: COSATU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/135389 , vital:37263
- Description: Privatisation is when government hands over the management or assets of government services to private interests. Privatised services don't provide well for the poor, who can't pay, because private interests must make profits. Government says it will ensure the poor get good services through contracts and regulations - but it doesn't have capacity to enforce them. Privatisation makes it harder to maintain cross subsidies. Cross subsidies mean rich communities or industry pay more, so that poor households can pay less. Getting rid of cross-subsidies tends to make the prices for services for the poor go up. Privatised companies don't take the broader economic needs of the country into account, for instance by buying goods locally as a way to create jobs, and providing affordable services in remote regions.
- Full Text:
- Date Issued: June 1991
Structural studies on the capsular antigens of Escherichia coli serotypes K102 and K47
- Authors: De Bruin, Aletta Hester
- Date: 1991
- Subjects: Escherichia -- Research , Klebsiella -- Research , Enterobacteriaceae -- Research , Antigens -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3754 , http://hdl.handle.net/10962/d1003232 , Escherichia -- Research , Klebsiella -- Research , Enterobacteriaceae -- Research , Antigens -- Research
- Description: The work presented in this thesis forms part of a continuing programme concerned with the structural determination of capsular polysaccharides of some Enterobacteriaceae. Since bacteria of this family are pathogenic to Man, work in this laboratory has focused on the structural elucidation of Klebsiella and, more recently, Escherichia coli ( E. coli) capsular polysaccharides ( K-antigens ). To date, some 74 K-antigens have been distinguished serologically within the genus E. coli and the structures of approximately 70% are known. In general, the K-antigens of the E. coli are characterized by a wide variety of constituent monosaccharides arranged in repeating units. In this thesis the structural elucidation of the capsular polysaccharides of E. coli serotypes 08: KI02: H- and 08: K47: H2 is presented. A variety of chemical techniques has been employed in the structural analysis, and are discussed. The thesis also includes extensive two-dimensional n.m.r. studies on the E. coli KI02 and K47 polysaccharides, as well as on a modified KI02 polymer produced after a lithium-ethylenediamine degradation of the native polysaccharide.
- Full Text:
- Date Issued: 1991
Studies in asymmetric synthesis
- Authors: Learmonth, Robin Alec
- Date: 1991
- Subjects: Organic compounds -- Synthesis Stereochemistry Organosilicon compounds Chirality Chemical tests and reagents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4353 , http://hdl.handle.net/10962/d1005018
- Description: The concept of combining two well established areas of organic chemistry, viz., organosilicon chemistry and the use of chiral auxiliaries, into a viable, alternative method of asymmetric synthesis has only very recently begun to receive attention. At the outset of this investigation, no asymmetric reactions of silyl enol ethers, chiral by virtue of optically active substituents on the silicon, had been reported. A range of novel chiral silyl enol ethers have thus been prepared from a variety of ketones, including pinacolone, cyclohexanone, and α-tetralone, and employing menthol, borneol, and cholesterol as chiral auxiliaries. These preparations have been achieved via several distinct routes, including a novel convergent approach involving the isolation of either the chloro(menthyloxy)dimethylsilane or the (bornyloxy)chlorodimethylsilane. The MS and NMR spectra of these silyl enol ethers were examined in detail and, in the case of the crystalline cholesteryloxy silyl enol ether, the X-ray structure has been determined. The potential of chloroalkoxysilanes to act as general, chiral derivatizing agents has been established by the preparation of diastereomeric silyl acetal mixtures of racemic secondary alcohols (e.g. I-phenylethanol and 2-octanol). The experimental diastereomeric ratios, obtained by GLC and ¹H NMR spectroscopy, approached the expected value of unity, confirming the potential of the alkoxychlorosilanes as chiral probes. The chiral silyl enol ethers have been successfully oxidized to the corresponding α-siloxy ketones employing MCPBA, MMPP, and 2-(phenylsulphonyl)-3-phenyloxaziridine as oxidizing agents and the diastereomeric excesses obtained, which varied from 0 to 16%, indicated some potential for stereochemical control. Alkylation and hydroxyalkylation reactions of the silyl enol ethers have yielded the expected α-iert-butyl and β-hydroxy ketones in good to excellent material yields, with the enantiomeric excesses, as determined by chiral shift reagent studies, reaching 14%. To improve the stereo control in these reactions, attempts have been made to prepare chiral silyl enol ethers with auxiliaries possessing the potential for transition state complex co-ordination in the reactions under consideration. The preparation of such silyl enol ethers, incorporating the proline-derived auxiliaries, N-methyl-2-hydroxymethylpyrrolidine and 2-methoxymethylpyrrolidine met with only limited success. In an alternative approach, three derivatives of 2,3-dihydroxybornane have been prepared. However, two of these auxiliaries, viz., 3-exo-benzyloxy-2-exo-hydroxybornane and 3-exo-(1-methoxyethoxy)-2-exo-hydroxybornane failed to form silyl enol ethers, even under considerably more vigorous conditions than normally employed. The third derivative, 3,3-ethylenedioxy-2-hydroxybornane has been successfully utilized in the preparation of a pinacolone-derived chiral silyl enol ether. Hydroxyalkylation of this compound with benzaldehyde has yielded the β-hydroxyketone with significantly improved enantiomeric excess (26%) and a transition state complex has been proposed to rationalize this improvement.
- Full Text:
- Date Issued: 1991
Studies on the Zoarcidae (Teleostei: Perciformes) of the Southern Hemisphere IV. New records and a new species from the Magellan Province of South America
- Authors: Anderson, M Eric , Gosztonyi, Atila E
- Date: 1991
- Language: English
- Type: Text
- Identifier: vital:14999 , http://hdl.handle.net/10962/d1019708 , ISSN 0073-4381 , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 55
- Description: New data on the eelpouts of the Magellan Province of South America are presented to include accounts of 10 of the 25 species presently known from the area. Aiakas zini, a second species for Aiakas Gosztonyi, 1977, is described as new. On the basis of material collected since the authors last published on the eelpouts of this region (1977 and 1988), enhanced descriptions are provided for Aiakas kreffti, Crossostomus chilensis, Lycenchelys bachmanni, Notolycodes schmidti, Oidiphoms brevis, Ophthalmolycus macrops and Pogonolycus marinae. Placed in synonymy are Crossostomus sobrali Lloris and Rucabado, 1987 with C. chilensis Regan, 1913, Iluocoetes facali Lloris and Rucabado, 1987 with I.fim- briatus Jenyns, 1842 and Haushia Lloris, 1988 with Pogonolycus Norman, 1937. Shorter accounts are provided for data from new specimens of Lycodonus malvinensis and Piedrabuenia ringueleti. A key to all of the species of Zoarcidae from the Magellan Province is included. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1991
Synthesis and interaction of secondary N-nitrosamines with acetylcholinesterase
- Authors: Mmutle, Tsietso Bernard
- Date: 1991
- Subjects: Chemistry, Physical and theoretical , Enzyme kinetics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4058 , http://hdl.handle.net/10962/d1004119 , Chemistry, Physical and theoretical , Enzyme kinetics
- Description: Secondary N-nitrosamines: diphenylnitrosamine (DPhNA), dimethylnitrosamine (DMNA), diethylnitrosamine (DENA), dipropylnitrosamine (DPNA), dibutylnitrosamine (DBNA), diethanolnitrosamine (DEtNA), methylnitrosoglycine (MNGly), nitrosopyrrolidine (NPyr), nitrosomorpholine (NMor) and nitrosopiperidine (NPip) were synthesised and their interaction with acetylcholinesterase (AChE) was investigated. Analyses of kinetic results show that DMNA (Ki=34.78 μM); DENA (Ki=54.24 μM); DPNA(Ki=60.36 μM); DBNA(Ki=95.54 μM); DEtNA(Ki=43.68 μM)MNGly (Ki=30.18 μM); NPip (Ki=123 μM); NPyr (Ki=66.07 μM), NMor (Ki=73.93 μM) and DPhNA (Ki=20.32 μM) are competitive and reversible inhibitors of acetylcholinesterase, with respect to the substrate, acetylthiocholine chloride, ATChCl. With time they act as irreversible covalent inhibitors with dipropy1nitrosamine producing 72% inactivation after 60 minutes. Scatchard analyses of f1uorometric titrations, (Kd=0.75mM-4.09mM); gel chromatography (Kd=O. 80mM-4. 60mM) and equilibrium dia1ysis (Kd=O. 71mM- 4.21mM) for MNG1y, DMNA, DEtNA, DENA, DPNA, NPyr, DSNA, NMor and NPip show that these compounds have weaker affinity for the enzyme, as compared to the much tightly binding aromatic DPhNA, Kd values (0.65mM, 0.68mM and 0.68mM) for fluorometric experiments, gel chromatography and equilibrium dialysis respectively. In all cases, the number of binding sites of acetylcholinesterase averaged to four.
- Full Text:
- Date Issued: 1991
The alluvial diamond deposits of the lower Vaal river between Barkly West and the Vaal-Harts confluence in the Northern Cape province, South Africa
- Authors: Matheys, Fabrice Gilbert
- Date: 1991
- Subjects: Diamond deposits -- South Africa , Geology, Economic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4933 , http://hdl.handle.net/10962/d1005545 , Diamond deposits -- South Africa , Geology, Economic
- Description: The alluvial diamond deposits along the Vaal River, between Barkly West and the Vaal-Harts confluence, have been worked for more than one century by thousands of private diggers. The diamonds are recovered from two sedimentary units of Cenozoic age, the Older Gravels and the Younger Gravels. These rest on a basement of Ventersdorp Supergroup andesites and Karoo Sequence sediments, which have been intruded by Cretaceous kimberlites. The gravels are, in turn, overlain by the Riverton Formation and the Hutton Sand. On a large scale, tectonic setting, geomorphology and palaeoclimate have played a major role in the formation of diamondiferous placers in the area under investigation. A study of the sedimentology of the Younger Gravels was carried out with the aim of acquiring an understanding of the processes responsible for the economic concentration of high quality diamonds. An investigation of facies assemblages, clast composition, clast size, palaeocurrent directions external geometry, particle morphology and led to the conclusion that the Younger Gravels were deposited in a proximal braided stream environment during high discharge. A small-scale experiment was carried out to test the efficiency of different sedimentological trap sites in concentrating kimberlite indicator minerals. The results show that the concentration of indicator minerals is dependent on the size fraction chosen, bed roughness and gravel calibre. The examination of surface features on pyrope, picroilmenite and chrome diopside from kimberlite led to the conclusion that most of these minerals are locally derived. Diamond grade variations within the Younger Gravels are influenced by a combination of factors, including bed roughness, channel width and sorting process from the source. Alluvial diamond exploration programmes must take into account the tectonic setting, the palaeoclimate, the level of erosion, the stability of the drainage system in the area as well as the presence of local trap sites in the river profile. It is concluded that the diamonds are the product of a long and complex process of erosion, reworking and concentration and are derived from Cretaceous kimberlites in the area.
- Full Text:
- Date Issued: 1991
The Behaviour Of Palewinged Starlings And A Comparison With Other Onychognathvs Species
- Authors: Craig, Adrian J F K , Hulley, Patrick E , Walter, Grenville H
- Date: 1991
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447868 , vital:74680 , https://doi.org/10.1080/00306525.1991.9639648
- Description: Pairs of Palewinged Starlings associate throughout the year and roost at the nest sites. Flock sizes are generally small, even during the non-breeding season. Allofeeding and allopreening have not been recorded. Wing displays emphasize the white region of the primaries. The territory appears to be restricted to the nest site. Interspecific aggression occurred between Redwinged and Palewinged Starlings, and was also directed at other Ed species frequenting the cliff. A form of ceremonial gathering occurs re in Palewinged Starlings. A review of the literature suggests that on behavioural grounds the Palewinged Starling shows no close affinity to the Redwinged Starfng or to any other member of the genus.
- Full Text:
- Date Issued: 1991