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Effects of temperature and salinity on the standard metabolic rate (SMR) of the caridean shrimp Palaemon peringueyiAllan, E.L., Froneman, P.W., Hodgson, A.N. 19 September 2006 (has links) (PDF)
The standard metabolic rate (SMR) of the caridean shrimp Palaemon peringueyi to changes in temperature (15–30 °C), salinity (0–45‰) and a combination thereof was investigated. The rate of oxygen consumption of the shrimp was determined using a YSI oxygen meter. At a constant salinity of 35‰ the respiration rate of P. peringueyi increased with an increase in temperature and ranged between 0.260 and 0.982 μl O[subscript 2] mg wwt[superscript −1] h[superscript −1]. The Q[subscript 10] value over the temperature range 15–25 °C was estimated at 3.13. At a constant temperature of 15 °C the respiration rate of P. peringueyi also increased with an increase in salinity and ranged between 0.231 and 0.860 μl O[subscript 2] mg wwt[superscript −1] h[superscript −1]. For combination experiments the absence of any significant difference in the respiration rate of P. peringueyi at the four temperatures over the salinity range 15–35‰ suggests that the shrimp is well adapted to inhabiting environments characterised by variations in salinity and temperature such as those encountered within the middle and lower reaches of permanently open estuaries with substantial freshwater inflow. On the other hand, the total mortality of the shrimp recorded at salinities < 5‰ at all four temperatures suggests that the upper distribution of the shrimp may reflect physiological constraints. Similarly, the increase in the respiration rate of the shrimp at the four temperatures at salinities > 35‰ suggests that the shrimp may experience osmotic stress in freshwater deprived permanently open and intermittently open estuaries where hypersaline conditions may develop.
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Deconstructing the Transvaal Supergroup, South Africa: implications for Palaeoproterozoic palaeoclimate modelsMoore, J.M., Tsikos, H., Polteau, S. January 2001 (has links) (PDF)
Current correlations between the Pretoria and Postmasburg Groups of the Transvaal Supergroup are shown to be invalid. The Postmasburg Group is also demonstrated to be broadly conformable with the underlying Ghaap Group and therefore considerably older (~2.4 Ga) than previously supposed. The new stratigraphy documents an extensive (100 Ma) and continuous cold-climate episode with a glacial maximum at the Makganyene Formation diamictite. Iron formations of the underlying Asbesheuwels and Koegas Subgroups and overlying Hotazel Formation have similar origins, related, respectively, to the onset and cessation of the glacial event. This interpretation of the Transvaal Supergroup stratigraphy has significant implications for various Palaeoproterozoic environmental models and for the timing of the development of an oxygenated atmosphere.
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Magma flow inferred from AMS fabrics in a layered mafic sill, Insizwa, South AfricaFerré, E.C., Bordarier, C., Marsh, J.S. 30 August 2002 (has links) (PDF)
The Insizwa sill, is a 25-km-diameter, >1000-m-thick layered mafic intrusion, part of the Karoo Igneous Province in South Africa. The peridotitic and gabbronoritic rocks are undeformed and mineral fabrics demonstrably result from magma flow. A horizontal, centimeter-scale model layering is visible in numerous outcrops. Plagioclase crystals are both tabular and elongated. Their preferred orientation, parallel to the layering, forms a foliation and a NW–SE lineation, respectively interpreted as the magma flow plane and flow direction. Throughout the 78 stations of this study (699 specimens), magnetic susceptibilities (K[subscript m]) range from 750 to 10,000×10[superscript (−6)] SI. The magnetic anisotropy (P[subscript j]) ranges from 1.03 to 1.08. Magnetic ellipsoids are both prolate and oblate (average T[subscript j]≈0). Anisotropy of magnetic susceptibility (AMS) fabrics are dominated by multidomain to pseudo-single domain magnetite. High-field magnetic experiments indicate that the paramagnetic contribution from the mafic silicates is less than 50% for low susceptibility rock types. The anisotropy results from magnetite grain shape solely as shown by no significant increase in P[subscript j] with increasing K[subscript m]. The magnetic lineation (305°, 05°) is consistent throughout the sill at various scales and coincides with the mineral lineation in average. In contrast, the magnetic foliation (125° NE 10°) is generally perpendicular to the mineral foliation and to the layering. Several explanations for this odd configuration are discussed. The variations of magnetic parameters across the layering and field observations point to a multiple injection. The magnetic lineation is consistent with the presence of a single feeder dike situated to the SE of the sill.
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Electrocatalysis of oxidation of 2-mercaptoethanol, l-cysteine and reduced glutathione by adsorbed and electrodeposited cobalt tetra phenoxypyrrole and tetra ethoxythiophene substituted phthalocyaninesSehlotho, N., Nyokong, T., Zagal, J.H., Bedioui, F. 15 July 2006 (has links) (PDF)
Catalytic activity of cobalt tetra ethoxythiophene and cobalt tetra phenoxypyrrole phthalocyanine complexes towards oxidation of 2-mercaptoethanol, L-cysteine and reduced glutathione is reported. It was found that the activity of the complexes depends on the substitution of the phthalocyanine ring, pH, film thickness and method of electrode modification. The high electrocatalytic activity obtained with adsorbed complexes in alkaline medium clearly demonstrates the necessity of modifying bare carbon electrodes to endow them with the desired behaviour.
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Towards a norm in South African Englishes: the case for Xhosa EnglishDe Klerk, V.A. 11 1900 (has links) (PDF)
Black South African English (BSAE) is generally regarded today as the variety of English commonly used by mother-tongue speakers of South Africa's indigenous African languages in areas where English is not the language of the majority. Its roots lie in the history of the teaching of English to the black people of this country, where the role models who teach English are second language learners themselves. To date, BSAE has mainly been studied within an applied linguistic framework with emphasis on its character as a second language which is deviant from standard English. An alternative view is to see it as a variety in its own right, a new or world English (Coetsee Van Rooy and Verhoef, 2000; van der Walt and van Rooy, 2002). As a consequence, a new look at norms is becoming increasingly necessary, so that decisions about learners' language competence can be made in terms of this variety. This paper reports on preliminary analyses of a recently collected corpus of Xhosa English (XE) (a sub-category of BSAE) which consists of naturalistic spoken data, and comprises some 540,000 words of Xhosa English. This large database enables empirical analysis of actual patterns of use in language, making it possible to test earlier speculations which have been based on intuition, and to explore the possibility of systematic differences in the patterns of structure and use in this particular variety. The paper focuses on 20 separate linguistic characteristics, most of which have been previously identified in the literature as being features of BSAE, and analyses each of them in turn, in order to ascertain their usage patterns and frequency of occurrence in the corpus.
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The doctrine of duress in the law of contract and unjustified enrichment in South AfricaGlover, Graham Brian January 2004 (has links) (PDF)
This thesis analyses the doctrine of duress and its application in the law of contract and unjustified enrichment in South Africa. Following an initial examination of the historical development of the doctrine from its roots in Roman and Roman-Dutch law, the study focuses on the current legal position in the two areas of law under review, identifies the substantive and formal deficiencies in the current approach, and suggests, using comparative authorities, how the law might be developed. As far as the law of contract is concerned, after exposing the difficulties inherent in the current approach, and placing the doctrine in its proper context in the South African law of contract generally, it is argued that the duress doctrine finds its juridical basis in the principle of good faith. A more modern and coherent test for duress is then proposed: one that concentrates on the question whether an illegitimate threat was made, which induced a contract in that it left the other person no reasonable choice but to succumb to the proposal. Additionally, the need for South African contract law to recognise and deal with cases of economic duress is emphasised. The study then shifts to an examination of the position in situations where non-contractual performances have occurred under duress: cases that are decided in terms of the principles of the law of unjustified enrichment. The current position is reviewed, and it is shown that the approach to duress cases is substantially different to the approach that applies in contract. An attempt is made to reconcile this problem. From a structural perspective, the nature and application of the relevant enrichment action where a non-contractual performance is made under duress (the condictio indebiti) is also investigated, in the light of approaches to enrichment adopted in both Germany and England, in an attempt to make better sense of this enrichment action in the South African context. The study closes with an analysis of the various contractual, delictual and enrichment remedies that are available once a case of duress has been proved.
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The discourse of postgraduate seminarsDe Klerk, V.A. January 1995 (has links) (PDF)
Video recordings of a range of postgraduate seminars in the Arts Faculty at a South African university were made and analyzed, in order to define the current nature of this particular form of educational practice in South African tertiary institutions. Recent demographic changes in formerly White universities are having a significant effect on the nature of interaction in formal discussion groups. Despite a common perception that at a tertiary level tutors and students are equally entitled to speak and all contributions equally valued, this article reveals that postgraduate seminars are sites of competition for the floor and that there are significant imbalances in participation by different groups in this competitive speaking environment; it is further argued that these imbalances reflect different (culture- and gender-specific) assumptions about what constitutes appropriate participation and also, to some degree, previous learned discourse patterns associated with schooling experience.
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English in the prison services: a case of breaking the law?De Klerk, V.A., Barkhuizen, G. 03 1900 (has links) (PDF)
In this paper we report on an investigation into the use of English in a prison in the Eastern Cape Province, run by the Department of Correctional Services (CS) five years after the declaration of an official multilingual policy. The investigation consisted of a range of interviews and observations in this institution, aimed at establishing the extent to which the national language policy is actually being implemented on the ground. Findings suggest that the use of English predominates in the high, official domains, that there is a marked avoidance of Afrikaans, and that Xhosa, the main language of the Eastern Cape Province, increasingly occupies the lower, unofficial domains. Tensions between policy and practice are discussed, and it is argued that the CS has shown that pragmatism is a much stronger force than ideology. While the roles of Xhosa and Afrikaans appear to be in the process of reversing in the Grahamstown prison, English has emerged as stronger there than it has ever been before. And because it will continue to be a necessary prerequisite for the mobility and promotion of staff in the country as a whole, and the lingua franca for an increasingly mobile criminal population (which means the prisons are likely to become increasingly linguistically diverse, rather than settling into regional patterns), everyone will have to have some proficiency in English, which, ironically, will promote and strengthen it even more.
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Nicknames as sex-role stereotypesDe Klerk, V.A., Bosch, B. 11 1900 (has links) (PDF)
Nicknames are powerful indicators of attitudes towards gender categories and because of their transient and optional nature, it has been argued that they are more likely to show a closer relationship to ongoing trends in the culture and society than other more fixed parts of the language E. B. Phillips (1990) ["Nicknames and Sex Role Stereotypes," Sex Roles, Vol. 23, pp. 281-289]. This study reports on a survey of nickname usage among a group of South African adolescents from mixed socioeconomic backgrounds (approximately 25% other than white) in an attempt to explicate gender-linked trends in frequency of occurrence, usage and attitudes to such special names. It reveals that conventions regarding nickname coinage and usage are intimately connected to the gender of bearers and users, and that more males have nicknames and coin them than females; it also shows significant sex-linked differences in the linguistic sources and users of nicknames, and reveals a greater tendency for female nicknames to function as indicators of affection rather than for humorous or critical effect. It could be argued that these trends could be linked to the nurturing and nurtured role of females in society, and to the differences in social power generally between males and females.
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Black South African English: where to from here?De Klerk, V.A. 10 1900 (has links) (PDF)
Black South African English is generally regarded as the variety of English commonly used by mother-tongue speakers of South Africa's indigenous African languages in areas where English is not the language of the majority. This paper explores some of the problems involved in defining this variety, problems such as whether it is a `new' variety of English or a dialect, and problems relating to whose English it is: the English of those learners who have encountered only a smattering of English in informal contexts or the variety of English acquired during formal schooling. The second half of the paper focuses on the possible future of Black South African English (BSAE) against the backdrop of South Africa's new multilingual policy. Reasons for the continued appeal of English are examined, alongside the range of factors influencing the possible future growth of BSAE as a distinct variety. It is argued that South Africans are unlikely ever to be free not to learn English, owing to the huge economic, political and ideological constraints which make the `choice' of English inevitable. The success of current efforts to resist value judgements and recognise the worth of BSAE will depend not only on the goodwill of South Africans, and on the cooperation of all speakers of English, world-wide, but on the rate at which the variety drifts away from recognised standard forms of English.
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