A contribution to the limnology of Swartvlei: the effect of physico-chemical factors upon primary and secondary production in the pelagic zone
- Authors: Robarts, R D (Richard D)
- Date: 1974
- Subjects: Limnology -- South Africa -- Swartvlei
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5822 , http://hdl.handle.net/10962/d1007474
- Description: From Resumé: The effect of physico-chemical factors on the biology of the upper reaches of Swartvlei has been investigated during 1971-1972. Physico-chemical data have shown that Swartvlei was characterized by an extremely labile ectogenic meromixis. This instability was due to three factors : (1) the inflow of freshwater, (2) the inflow of sea water, and (3) wind stress. The magnitude of the effects of these factors upon the physics, chemistry and biology of the upper reaches was dependent upon whether or not the estuary mouth was open or closed. The phytoplankton of the pelagic zone of Swartvlei was dominated by nannoplankton. Three major categories were recorded: dinoflagellates, flagellates and diatoms. The major factor regulating their productivity in the upper reaches was light. As a result of humate staining and suspended detrital matter light conditions in Swartvlei were comparable to those in extremely eutrophic northern hemisphere lakes. A maximum integral primary productivity of 39.66 mg C m⁻² h⁻¹ was recorded in November 1972. The aerobic heterotrophic bacterial population in Swartvlei was usually less than 300 col. ml⁻¹ (plate counts). The activity of the total microbial population was measured with ¹⁴C techniques. Uptake of acetate was dominated by flagellates and one species of dinoflagellate when they were present. Glucose uptake was due to bacteria as was acetate uptake in the absence of heterotrophic phytoplankton. Glucose uptake was usually greatest in the anaerobic zone. This, and the presence of H₂S, suggested that a large active photosynthetic and chemosynthetic bacterial population may have been present in the monimolimnion. The possible importance of these bacterial processes in the total productivity of the pelagic zone of Swartvlei was discussed. Daytime zooplankton population size was statistically correlated with the size of the flagellate population. The zooplankton was dominated by Acartia and Halicyclops. These two animals were found in the anaerobic bottom of Swartvlei after October 1971. This corresponded to the disappearance of the flagellate population from the water column. The dominance of these animals in the zooplankton population may have been related to their ability to live in anaerobic water where the bacterial population appeared to be considerably more abundant than in the aerobic zone. Further implications of the results are discussed in reference to phytoplankton cell size and heterotrophy indicating a possible adaptive significance of these factors in Swartvlei.
- Full Text:
- Date Issued: 1974
- Authors: Robarts, R D (Richard D)
- Date: 1974
- Subjects: Limnology -- South Africa -- Swartvlei
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5822 , http://hdl.handle.net/10962/d1007474
- Description: From Resumé: The effect of physico-chemical factors on the biology of the upper reaches of Swartvlei has been investigated during 1971-1972. Physico-chemical data have shown that Swartvlei was characterized by an extremely labile ectogenic meromixis. This instability was due to three factors : (1) the inflow of freshwater, (2) the inflow of sea water, and (3) wind stress. The magnitude of the effects of these factors upon the physics, chemistry and biology of the upper reaches was dependent upon whether or not the estuary mouth was open or closed. The phytoplankton of the pelagic zone of Swartvlei was dominated by nannoplankton. Three major categories were recorded: dinoflagellates, flagellates and diatoms. The major factor regulating their productivity in the upper reaches was light. As a result of humate staining and suspended detrital matter light conditions in Swartvlei were comparable to those in extremely eutrophic northern hemisphere lakes. A maximum integral primary productivity of 39.66 mg C m⁻² h⁻¹ was recorded in November 1972. The aerobic heterotrophic bacterial population in Swartvlei was usually less than 300 col. ml⁻¹ (plate counts). The activity of the total microbial population was measured with ¹⁴C techniques. Uptake of acetate was dominated by flagellates and one species of dinoflagellate when they were present. Glucose uptake was due to bacteria as was acetate uptake in the absence of heterotrophic phytoplankton. Glucose uptake was usually greatest in the anaerobic zone. This, and the presence of H₂S, suggested that a large active photosynthetic and chemosynthetic bacterial population may have been present in the monimolimnion. The possible importance of these bacterial processes in the total productivity of the pelagic zone of Swartvlei was discussed. Daytime zooplankton population size was statistically correlated with the size of the flagellate population. The zooplankton was dominated by Acartia and Halicyclops. These two animals were found in the anaerobic bottom of Swartvlei after October 1971. This corresponded to the disappearance of the flagellate population from the water column. The dominance of these animals in the zooplankton population may have been related to their ability to live in anaerobic water where the bacterial population appeared to be considerably more abundant than in the aerobic zone. Further implications of the results are discussed in reference to phytoplankton cell size and heterotrophy indicating a possible adaptive significance of these factors in Swartvlei.
- Full Text:
- Date Issued: 1974
John Wesley's means of evangelism
- Authors: Gribble, James
- Date: 1974
- Subjects: Wesley, John, 1703-1791 Evangelistic work Methodist Church -- Doctrines
- Language: English
- Type: Thesis , Bachelor , BDiv
- Identifier: vital:1255 , http://hdl.handle.net/10962/d1012096
- Description: This essay is an attempt to evaluate the methods of evangelism used by John Wesley during the course of his long ministry in the eighteenth century. Wesley's methods are important, since by their use he exercised a remarkable influence upon the religious and social life of eighteenth-century England. They have a continuing importance, too, for a Church that wants to carry out her Lord's "Great Commission" effectively. In the history of the Church Wesley stands in the front rank of those who have significantly carried forward the mission of the Church. Therefore we do well to pause and learn what we can from his example and experience. Intro., p. 1.
- Full Text:
- Date Issued: 1974
- Authors: Gribble, James
- Date: 1974
- Subjects: Wesley, John, 1703-1791 Evangelistic work Methodist Church -- Doctrines
- Language: English
- Type: Thesis , Bachelor , BDiv
- Identifier: vital:1255 , http://hdl.handle.net/10962/d1012096
- Description: This essay is an attempt to evaluate the methods of evangelism used by John Wesley during the course of his long ministry in the eighteenth century. Wesley's methods are important, since by their use he exercised a remarkable influence upon the religious and social life of eighteenth-century England. They have a continuing importance, too, for a Church that wants to carry out her Lord's "Great Commission" effectively. In the history of the Church Wesley stands in the front rank of those who have significantly carried forward the mission of the Church. Therefore we do well to pause and learn what we can from his example and experience. Intro., p. 1.
- Full Text:
- Date Issued: 1974
The musical life of Henry Hare Dugmore, 1820 settler
- Authors: Henderson, Jenifer M
- Date: 1974
- Subjects: Dugmore, H H (Henry H), 1810-1897
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: vital:2682 , http://hdl.handle.net/10962/d1012262
- Description: Henry Hare Dugmore, the eldest son of Isaac and Maria, was destined to play his part in the dramatic future of his adopted country; not only to help as an artisan and a farmer, but to build in the spiritual field as an influential missionary and in the academic field as a most capable lecturer; most important of all, in the Artistic field as a Poet and a Musician.
- Full Text:
- Date Issued: 1974
- Authors: Henderson, Jenifer M
- Date: 1974
- Subjects: Dugmore, H H (Henry H), 1810-1897
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: vital:2682 , http://hdl.handle.net/10962/d1012262
- Description: Henry Hare Dugmore, the eldest son of Isaac and Maria, was destined to play his part in the dramatic future of his adopted country; not only to help as an artisan and a farmer, but to build in the spiritual field as an influential missionary and in the academic field as a most capable lecturer; most important of all, in the Artistic field as a Poet and a Musician.
- Full Text:
- Date Issued: 1974
The Grahamstown Fine Art Association
- Authors: Cook, J C W
- Date: 1974
- Subjects: Grahamstown Fine Art Association Rhodes University -- History Artists -- South Africa Painters -- South Africa Rhodes University -- School of Art
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2476 , http://hdl.handle.net/10962/d1010601
- Description: When he opened the 24th annual exhibition of students' work on the 1st July, 1927, Professor F.W. Armstrong gave the following account of the beginnings of the Grahamstown School of Art: ... The appointment of a master was the responsibility of Sir Langham Dale, the Superintendent General of Education in the Cape Colony. His choice for the first art master of the Grahamstown School of Art was Mr.W. H. Simpson. Simpson had studied at the South Kensington Museum then at the Royal Academy. During the 1870's he had exhibited in the Royal Academy, at other exhibitions in London, and in the provinces. Intro. p. 1.
- Full Text:
- Date Issued: 1974
- Authors: Cook, J C W
- Date: 1974
- Subjects: Grahamstown Fine Art Association Rhodes University -- History Artists -- South Africa Painters -- South Africa Rhodes University -- School of Art
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2476 , http://hdl.handle.net/10962/d1010601
- Description: When he opened the 24th annual exhibition of students' work on the 1st July, 1927, Professor F.W. Armstrong gave the following account of the beginnings of the Grahamstown School of Art: ... The appointment of a master was the responsibility of Sir Langham Dale, the Superintendent General of Education in the Cape Colony. His choice for the first art master of the Grahamstown School of Art was Mr.W. H. Simpson. Simpson had studied at the South Kensington Museum then at the Royal Academy. During the 1870's he had exhibited in the Royal Academy, at other exhibitions in London, and in the provinces. Intro. p. 1.
- Full Text:
- Date Issued: 1974
The animal as a sacred symbol in prehistoric art
- Van Heerden, Johannes Lodewicus
- Authors: Van Heerden, Johannes Lodewicus
- Date: 1974
- Subjects: Art, Prehistoric Animals in art Animals, Mythical, in art
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2449 , http://hdl.handle.net/10962/d1007286
- Description: From Thesis: Why the animal as our point of departure in this discussion of prehistoric art, and why as a sacred symbol? Prehistoric art stretched over an immensely long period, from the first evidence of the activities of Neanderthal tribes during the Mousterian period, ± 35,000 B.C., to the end of the Magdalenian, ± 8,000 B.C. We are dealing with a time-span of nearly 30,000 years, during which a strictly Zoomorphic attitude existed. The animal was the dominant feature. It was constantly used in the decoration of cave walls, on engraved stone slabs, and on all kinds of utilitarian objects.
- Full Text:
- Date Issued: 1974
- Authors: Van Heerden, Johannes Lodewicus
- Date: 1974
- Subjects: Art, Prehistoric Animals in art Animals, Mythical, in art
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2449 , http://hdl.handle.net/10962/d1007286
- Description: From Thesis: Why the animal as our point of departure in this discussion of prehistoric art, and why as a sacred symbol? Prehistoric art stretched over an immensely long period, from the first evidence of the activities of Neanderthal tribes during the Mousterian period, ± 35,000 B.C., to the end of the Magdalenian, ± 8,000 B.C. We are dealing with a time-span of nearly 30,000 years, during which a strictly Zoomorphic attitude existed. The animal was the dominant feature. It was constantly used in the decoration of cave walls, on engraved stone slabs, and on all kinds of utilitarian objects.
- Full Text:
- Date Issued: 1974
Genetic studies on collagenolytic achromobacter strains and their bacteriophages
- Authors: Thomson, Jennifer Ann
- Date: 1974
- Subjects: Bacteriophages -- Genetics Bacterial genetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4246 , http://hdl.handle.net/10962/d1007291
- Description: From Summary: A survey of collagenolytic aerobic bacteria from cured hides yielded three strains of Bacillus and eight of Achromobacter which degraded collagen at 0.4 M NaCl. Achromobacter sp. 2 was chosen for genetic studies due to its high collagenolytic activity and the lack of genetic information on Achromobacter. Four temperate bacteriophages specific for Achromobacter sp. 2 were isolated and their relationships studied. The phages caused lysogenic conversion resulting in the inability of lysogens to adsorb phage. Achromobacter sp. 2 was shown to be a cryptic lysogen as it was not immune to superinfection but had a very low rate of spontaneous induction which could be increased with mutagens. It is proposed that the cryptic lysogeny of this strain is maintained by a defective excision mechanism and the mode of prophage integration in the host chromosome. DNA extracted from phage α3a was used to transfect spheroplasts. The optimal conditions for the development of competence for transfection were determined. The presence of nuclease-attack on phage DNA under conditions of prolonged incubation of DNA and spheroplasts was proposed. A method for extracting Achromobacter DNA was devised which yielded purified, undegraded DNA, but it was not possible to transform Achromobacter sp. 2 with this DNA. The a phages were used to transduce a number of genetic markers into Achromobacter auxotrophs. The transduct ants had the ability to release the cryptic α3 prophage at a high rate while maintaining their sensitivity to homologous phage infection. It is proposed that this is due to complementation between the cryptic prophage and the residual phage functions in the transducing particles. The transductants segregated auxotrophs with a probability of 10⁻³ per cell per generation. It appears that an unusual system of generalised transduction is operating whereby the transducing particles contain both phage and bacterial DNA which is incorporated into the recipient genome by a single recombination event yielding unstable transductants. In a study on induction of Escherichia coli (λ), carcinogenic nitrosamines were shown to be inducers of phage development. This provides a screening system for potentially harmful nitrosamines.
- Full Text:
- Date Issued: 1974
- Authors: Thomson, Jennifer Ann
- Date: 1974
- Subjects: Bacteriophages -- Genetics Bacterial genetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4246 , http://hdl.handle.net/10962/d1007291
- Description: From Summary: A survey of collagenolytic aerobic bacteria from cured hides yielded three strains of Bacillus and eight of Achromobacter which degraded collagen at 0.4 M NaCl. Achromobacter sp. 2 was chosen for genetic studies due to its high collagenolytic activity and the lack of genetic information on Achromobacter. Four temperate bacteriophages specific for Achromobacter sp. 2 were isolated and their relationships studied. The phages caused lysogenic conversion resulting in the inability of lysogens to adsorb phage. Achromobacter sp. 2 was shown to be a cryptic lysogen as it was not immune to superinfection but had a very low rate of spontaneous induction which could be increased with mutagens. It is proposed that the cryptic lysogeny of this strain is maintained by a defective excision mechanism and the mode of prophage integration in the host chromosome. DNA extracted from phage α3a was used to transfect spheroplasts. The optimal conditions for the development of competence for transfection were determined. The presence of nuclease-attack on phage DNA under conditions of prolonged incubation of DNA and spheroplasts was proposed. A method for extracting Achromobacter DNA was devised which yielded purified, undegraded DNA, but it was not possible to transform Achromobacter sp. 2 with this DNA. The a phages were used to transduce a number of genetic markers into Achromobacter auxotrophs. The transduct ants had the ability to release the cryptic α3 prophage at a high rate while maintaining their sensitivity to homologous phage infection. It is proposed that this is due to complementation between the cryptic prophage and the residual phage functions in the transducing particles. The transductants segregated auxotrophs with a probability of 10⁻³ per cell per generation. It appears that an unusual system of generalised transduction is operating whereby the transducing particles contain both phage and bacterial DNA which is incorporated into the recipient genome by a single recombination event yielding unstable transductants. In a study on induction of Escherichia coli (λ), carcinogenic nitrosamines were shown to be inducers of phage development. This provides a screening system for potentially harmful nitrosamines.
- Full Text:
- Date Issued: 1974
Physico-chemical and substructural studies on Nudaurelia capensis β virus
- Authors: Struthers, J Keith
- Date: 1974
- Subjects: Imbrasia cytherea , Insects -- Viruses , RNA viruses , DNA
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4075 , http://hdl.handle.net/10962/d1007327 , Imbrasia cytherea , Insects -- Viruses , RNA viruses , DNA
- Description: From Introduction: The pine emperor moth, Nudaurelia cytherea capensis Stoll is an insect which, during the larval stage, causes extensive defoliation of the pine tree, Pinus radiata in the Cape province. These insects are susceptible to a virus disease, which on occasions causes large scale mortality. Five nonoccluded viruses have been shown to infect the pine emperor moth, and of these, one found in the greatest concentration, Nudaurelia capensis β virus (NβV) has been characterised to the greatest extent. This virus has been shown to contain RNA, to be isometric with a diameter of 36 mm, and to have a molecular weight of 16 million. The virus occurs in all stages of the insect's development, and by fluorescent antibody staining has been shown to develop in the cytoplasm of the host's cells. There have in recent years been a number of reports describing nonoccluded RNA viruses which appear to be similar to NβV. These are the viruses isolated from the moths Gonometa podocarpi and Antheraea eucalypti, and the one from the citrus red mite, Panonychus citri. These viruses have not been as extensively characterised as NβV, so the extent of the similarity between them and NβV is not known. However it would appear as if their discovery collectively heralds the emergence of a distinct new grouping within the nonoccluded RNA viruses of insects. This work reports the isolation and further characterisation of N. capensis β virus, its protein and nucleic acid.
- Full Text:
- Date Issued: 1974
- Authors: Struthers, J Keith
- Date: 1974
- Subjects: Imbrasia cytherea , Insects -- Viruses , RNA viruses , DNA
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4075 , http://hdl.handle.net/10962/d1007327 , Imbrasia cytherea , Insects -- Viruses , RNA viruses , DNA
- Description: From Introduction: The pine emperor moth, Nudaurelia cytherea capensis Stoll is an insect which, during the larval stage, causes extensive defoliation of the pine tree, Pinus radiata in the Cape province. These insects are susceptible to a virus disease, which on occasions causes large scale mortality. Five nonoccluded viruses have been shown to infect the pine emperor moth, and of these, one found in the greatest concentration, Nudaurelia capensis β virus (NβV) has been characterised to the greatest extent. This virus has been shown to contain RNA, to be isometric with a diameter of 36 mm, and to have a molecular weight of 16 million. The virus occurs in all stages of the insect's development, and by fluorescent antibody staining has been shown to develop in the cytoplasm of the host's cells. There have in recent years been a number of reports describing nonoccluded RNA viruses which appear to be similar to NβV. These are the viruses isolated from the moths Gonometa podocarpi and Antheraea eucalypti, and the one from the citrus red mite, Panonychus citri. These viruses have not been as extensively characterised as NβV, so the extent of the similarity between them and NβV is not known. However it would appear as if their discovery collectively heralds the emergence of a distinct new grouping within the nonoccluded RNA viruses of insects. This work reports the isolation and further characterisation of N. capensis β virus, its protein and nucleic acid.
- Full Text:
- Date Issued: 1974
The development and failure of the Eastern Cape separatist movement with special reference to John Paterson
- Authors: Stead, J L
- Date: 1974
- Subjects: Paterson, John, 1822-1880 , Cape of Good Hope (South Africa) -- Politics and government -- 1795-1872 , Eastern Cape (South Africa) -- History -- Autonomy and independence movements , Stormberg Range Region (South Africa) -- History
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2593 , http://hdl.handle.net/10962/d1007343
- Description: From Preface: In 1960 Pamela Ffolliott and E.L.H. Croft wrote a biograpby of John Paterson entitled One Titan at a Time. This concentrated mainly on his business activities and his civic role to the virtual exclusion of his political opinions and career even though contemporaries often regarded him as second only to John X. Merriman. The result of diligent enquiry for further biographical detail both in South Africa and in the United Kingdom has been disappointing. A close examination of such evidence as there is, suggests that his political abilities have been over-rated rather than under-rated. It is now nearly forty years since the study of separatism was first seriously undertaken. The period 1854-72 was studied by N.H. Taylor (M.A. Thesis, University of Cape Town, 1938) and D.B. Sole undertook a broader survey (M.A. Thesis, University of South Africa (R.U.C.), 1939). Neither study used the Godlonton papers. The Godlonton-White correspondence is at Rhodes House, Oxford and this mainly concerns business matters and news of prominent local people. The collection of Godlonton papers housed in the Historical Papers section of the Library of the University of the Witwatersrand proved more interesting. The use of these papers made it possible to make a new approach to the critical period of representative government and to explore in more detail lines suggested in part by J .L. McCracken in the more general study, The Cape Parliament 1854-1910 published in 1967. Yet because in many cases the leaders of the movement after 1854 carried into the new era ideas and attitudes formed in earlier years, it was necessary to consider also the origins of the separatist impulse. Separatism had many roots: as a term it had many meanings. Clearly the meaning attached to the word varied from time to time, from place to place and even from person to person. The goal varied too. Sometimes the Eastern Province wanted to move the centre of government from Cape Town; sometimes the cry was for a completely separate colony to be established in the East; sometimes the theme was federal devolution of powers, to a resident government. Indeed among the many reasons for the failure of the separatist movement was the inability of the Easterners to agree among themselves about what they were seeking. This exposed and emphasised their political ineptitude.
- Full Text:
- Date Issued: 1974
- Authors: Stead, J L
- Date: 1974
- Subjects: Paterson, John, 1822-1880 , Cape of Good Hope (South Africa) -- Politics and government -- 1795-1872 , Eastern Cape (South Africa) -- History -- Autonomy and independence movements , Stormberg Range Region (South Africa) -- History
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2593 , http://hdl.handle.net/10962/d1007343
- Description: From Preface: In 1960 Pamela Ffolliott and E.L.H. Croft wrote a biograpby of John Paterson entitled One Titan at a Time. This concentrated mainly on his business activities and his civic role to the virtual exclusion of his political opinions and career even though contemporaries often regarded him as second only to John X. Merriman. The result of diligent enquiry for further biographical detail both in South Africa and in the United Kingdom has been disappointing. A close examination of such evidence as there is, suggests that his political abilities have been over-rated rather than under-rated. It is now nearly forty years since the study of separatism was first seriously undertaken. The period 1854-72 was studied by N.H. Taylor (M.A. Thesis, University of Cape Town, 1938) and D.B. Sole undertook a broader survey (M.A. Thesis, University of South Africa (R.U.C.), 1939). Neither study used the Godlonton papers. The Godlonton-White correspondence is at Rhodes House, Oxford and this mainly concerns business matters and news of prominent local people. The collection of Godlonton papers housed in the Historical Papers section of the Library of the University of the Witwatersrand proved more interesting. The use of these papers made it possible to make a new approach to the critical period of representative government and to explore in more detail lines suggested in part by J .L. McCracken in the more general study, The Cape Parliament 1854-1910 published in 1967. Yet because in many cases the leaders of the movement after 1854 carried into the new era ideas and attitudes formed in earlier years, it was necessary to consider also the origins of the separatist impulse. Separatism had many roots: as a term it had many meanings. Clearly the meaning attached to the word varied from time to time, from place to place and even from person to person. The goal varied too. Sometimes the Eastern Province wanted to move the centre of government from Cape Town; sometimes the cry was for a completely separate colony to be established in the East; sometimes the theme was federal devolution of powers, to a resident government. Indeed among the many reasons for the failure of the separatist movement was the inability of the Easterners to agree among themselves about what they were seeking. This exposed and emphasised their political ineptitude.
- Full Text:
- Date Issued: 1974
Ligand substitution effects in uranyl ο-hydroxyarylcarbonyl complexes
- Authors: Haigh, John M
- Date: 1974
- Language: English
- Type: text , Article
- Identifier: vital:6372 , http://hdl.handle.net/10962/d1006075
- Description: Twenty-two base adducts of uranyl o-hydroxyarylcarbonyl complexes [UO2L2B] (L = o-hydroxyarylcarbonyl compound, B = H2O, pyridine, pyridine N-oxide) have been prepared. Pure field substituent parameters are used to derive a quantitative order of the electronic effects of the chelate ring substituents. Values of v(U=O) correlate well with these values. Evidence is cited suggesting almost complete non-aromaticity of the chelate ring, and the transmission of the electronic effects of the chelate ring substituent through the uranium atom in the pyridine and pyridine N-oxide base adducts.
- Full Text:
- Date Issued: 1974
- Authors: Haigh, John M
- Date: 1974
- Language: English
- Type: text , Article
- Identifier: vital:6372 , http://hdl.handle.net/10962/d1006075
- Description: Twenty-two base adducts of uranyl o-hydroxyarylcarbonyl complexes [UO2L2B] (L = o-hydroxyarylcarbonyl compound, B = H2O, pyridine, pyridine N-oxide) have been prepared. Pure field substituent parameters are used to derive a quantitative order of the electronic effects of the chelate ring substituents. Values of v(U=O) correlate well with these values. Evidence is cited suggesting almost complete non-aromaticity of the chelate ring, and the transmission of the electronic effects of the chelate ring substituent through the uranium atom in the pyridine and pyridine N-oxide base adducts.
- Full Text:
- Date Issued: 1974
Effects of precipitating electrons in the ionosphere
- Authors: Haschick, Aubrey D
- Date: 1974
- Subjects: Electrons , Electron precipitation , Ionosphere , Ionospheric electron density
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5526 , http://hdl.handle.net/10962/d1012220
- Description: As early as 1896, around the time of the discovery of the electron by J.J. Thompson, Birkeland was led to propose that aurorae were caused by fast moving electrons or similarly charged particles emitted by the sun and 'sucked in towards' the auroral zones by the geomagnetic field. He later supported this idea by firing electrons at a dipole field surrounding a sphere covered with a fluorescent coating. Extensive ground based observations of auroral features eventually led, in 1950, to the initial direct evidence of the fact that auroral emissions are due to energetic charged particles, consisting partly of protons, entering the earth's atmosphere (Meinel, 1951). However, it was only in 1952 and 1953 that the first measurements of what was later interpreted as bremsstrahlung X- rays from precipitating electrons were made at auroral latitudes. (Meredith et aI, 1955) During the IGY, 1957 - 1958, a number of rockets were fired through and near, visible aurorae and large fluxes of low energy electrons were detected ... Intro., p. 1.
- Full Text:
- Date Issued: 1974
- Authors: Haschick, Aubrey D
- Date: 1974
- Subjects: Electrons , Electron precipitation , Ionosphere , Ionospheric electron density
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5526 , http://hdl.handle.net/10962/d1012220
- Description: As early as 1896, around the time of the discovery of the electron by J.J. Thompson, Birkeland was led to propose that aurorae were caused by fast moving electrons or similarly charged particles emitted by the sun and 'sucked in towards' the auroral zones by the geomagnetic field. He later supported this idea by firing electrons at a dipole field surrounding a sphere covered with a fluorescent coating. Extensive ground based observations of auroral features eventually led, in 1950, to the initial direct evidence of the fact that auroral emissions are due to energetic charged particles, consisting partly of protons, entering the earth's atmosphere (Meinel, 1951). However, it was only in 1952 and 1953 that the first measurements of what was later interpreted as bremsstrahlung X- rays from precipitating electrons were made at auroral latitudes. (Meredith et aI, 1955) During the IGY, 1957 - 1958, a number of rockets were fired through and near, visible aurorae and large fluxes of low energy electrons were detected ... Intro., p. 1.
- Full Text:
- Date Issued: 1974
Some adaptations of myrmeleontid (Neuroptera) and rhagionid (Diptera) larvae to life in hot dry sand
- Authors: Youthed, Gayle Jean
- Date: 1974
- Subjects: Ant lions Rhagionidae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5818 , http://hdl.handle.net/10962/d1007228
- Description: From Introduction: Larvae of the families Myrmeleontidae, Neuroptera, (ant-lions) and Rhagionidae, Diptera, (worm-lions) all live in hot dry sand. Many of the ant-lion larvae and all the worm-lion larvae, construct small conical pits in the sand which are used for the capture of prey (Haub, 1942; Youthed and Horan, 1969a). Those ant-lion larvae which do not construct pits lie in wait for their prey just below the surface of the sand.
- Full Text:
- Date Issued: 1974
Some adaptations of myrmeleontid (Neuroptera) and rhagionid (Diptera) larvae to life in hot dry sand
- Authors: Youthed, Gayle Jean
- Date: 1974
- Subjects: Ant lions Rhagionidae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5818 , http://hdl.handle.net/10962/d1007228
- Description: From Introduction: Larvae of the families Myrmeleontidae, Neuroptera, (ant-lions) and Rhagionidae, Diptera, (worm-lions) all live in hot dry sand. Many of the ant-lion larvae and all the worm-lion larvae, construct small conical pits in the sand which are used for the capture of prey (Haub, 1942; Youthed and Horan, 1969a). Those ant-lion larvae which do not construct pits lie in wait for their prey just below the surface of the sand.
- Full Text:
- Date Issued: 1974
Aspects of the theory of human capital and its application to South African economic development
- Authors: Bates, Terrence
- Date: 1974
- Subjects: Human capital -- South Africa , South Africa -- Economic conditions -- 1961-1991
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1064 , http://hdl.handle.net/10962/d1007608 , Human capital -- South Africa , South Africa -- Economic conditions -- 1961-1991
- Description: Human capital is an important economic concept. The significance of human resource development, in the form of both education and health, has long been realised and was stressed even in the writings of the early economists. Introduction, p.1
- Full Text:
- Date Issued: 1974
- Authors: Bates, Terrence
- Date: 1974
- Subjects: Human capital -- South Africa , South Africa -- Economic conditions -- 1961-1991
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1064 , http://hdl.handle.net/10962/d1007608 , Human capital -- South Africa , South Africa -- Economic conditions -- 1961-1991
- Description: Human capital is an important economic concept. The significance of human resource development, in the form of both education and health, has long been realised and was stressed even in the writings of the early economists. Introduction, p.1
- Full Text:
- Date Issued: 1974
Albany Rugby Football Club 1st XV, 1974
- Date: 1974
- Subjects: Rugby football -- South Africa -- Eastern Cape -- Photographs , Albany Rugby Football Club -- Photographs
- Type: still image
- Identifier: http://hdl.handle.net/10962/50701 , vital:26018 , This image is held at the Cory Library for Humanities Research at Rhodes University. For further information contact cory@ru.ac.za. The digitisation of this image was made possible through a generous grant received from the Andrew W. Mellon Foundation 2014-2017. , PIC/M 6702
- Description: Albany Rugby Football Club 1st XV 1974, 1st XV – 1974,Team photograph with rugby/football players, in rugby uniform, Group photograph, Black and white photograph, Indoor photograph, Framed photographs against wall in background, President, Club Captain and Coach wearing suits, Captain holding rugby ball with “1974” on it, Players standing have arms by side, Players sitting have hands in lap, Standing (left to right): A Marais, R. Snow, R. Green, B. Shone, P. van Rensburg, S. Long, D. J. Mills, S. Hill, Sitting: (left to right): L. Webster, R. Carlson, J. Place (President), B. Carlson (Captain), P. Long (Club-Captain), Major Bakkes (Coach), R. Moss, Front (left to right): A. Austin, C. Reed, Absent: C. Pascoe.
- Full Text: false
- Date Issued: 1974
- Date: 1974
- Subjects: Rugby football -- South Africa -- Eastern Cape -- Photographs , Albany Rugby Football Club -- Photographs
- Type: still image
- Identifier: http://hdl.handle.net/10962/50701 , vital:26018 , This image is held at the Cory Library for Humanities Research at Rhodes University. For further information contact cory@ru.ac.za. The digitisation of this image was made possible through a generous grant received from the Andrew W. Mellon Foundation 2014-2017. , PIC/M 6702
- Description: Albany Rugby Football Club 1st XV 1974, 1st XV – 1974,Team photograph with rugby/football players, in rugby uniform, Group photograph, Black and white photograph, Indoor photograph, Framed photographs against wall in background, President, Club Captain and Coach wearing suits, Captain holding rugby ball with “1974” on it, Players standing have arms by side, Players sitting have hands in lap, Standing (left to right): A Marais, R. Snow, R. Green, B. Shone, P. van Rensburg, S. Long, D. J. Mills, S. Hill, Sitting: (left to right): L. Webster, R. Carlson, J. Place (President), B. Carlson (Captain), P. Long (Club-Captain), Major Bakkes (Coach), R. Moss, Front (left to right): A. Austin, C. Reed, Absent: C. Pascoe.
- Full Text: false
- Date Issued: 1974
"Complexes of carbohydrates with magnesium-ions" : "the isolation of an oligosaccharide containing L-galactose from the polysaccharide of Aeodes orbitosa" : "horizontal cellulose colum chromatography of sugars"
- Authors: Van der Linde, Michael John
- Date: 1974
- Subjects: Magenesium , Ions , Carbohydrates , Oligosaccharides , Polysaccharides , Chromatographic analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4504 , http://hdl.handle.net/10962/d1013282
- Description: Sugar complexes with anions and cations are reviewed. Evidence is presented for the formation of a complex of stoichiometry 1:1 in aqueous solution between methyl-α-Dglucopyranoside and magnesium perchlorate. The complex may be detected by the method of continuous variations. Measurements of changes in the proton chemical shifts of the glucoside in dauterium oxide, indicate that the complex is probably formed between the vicinal hydroxyl groups at C-2 and C-3 of the pyranoside ring and the hydrated cation. At elevation temperatures there is evidence for the presence of a complex of stoichiometry 2:1. Experiments conducted on cellulose indicate the possible formation of cellulose - magnesium-ion complexes . These complexes provide an explanation for the "protective action" of mEgnesium compounds on the cellulose portion of pulp during alkali-oxygen bleaching.
- Full Text:
- Date Issued: 1974
- Authors: Van der Linde, Michael John
- Date: 1974
- Subjects: Magenesium , Ions , Carbohydrates , Oligosaccharides , Polysaccharides , Chromatographic analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4504 , http://hdl.handle.net/10962/d1013282
- Description: Sugar complexes with anions and cations are reviewed. Evidence is presented for the formation of a complex of stoichiometry 1:1 in aqueous solution between methyl-α-Dglucopyranoside and magnesium perchlorate. The complex may be detected by the method of continuous variations. Measurements of changes in the proton chemical shifts of the glucoside in dauterium oxide, indicate that the complex is probably formed between the vicinal hydroxyl groups at C-2 and C-3 of the pyranoside ring and the hydrated cation. At elevation temperatures there is evidence for the presence of a complex of stoichiometry 2:1. Experiments conducted on cellulose indicate the possible formation of cellulose - magnesium-ion complexes . These complexes provide an explanation for the "protective action" of mEgnesium compounds on the cellulose portion of pulp during alkali-oxygen bleaching.
- Full Text:
- Date Issued: 1974
Social criteria in the drama of Molìère
- Authors: Brooks, Beverley Anne
- Date: 1974
- Subjects: Molière, 1622-1673 -- Criticism and interpretation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3627 , http://hdl.handle.net/10962/d1009758
- Description: It is by no means an easy task to analyse and interpret the work of a dramatist such as Molière, for an interval of three hundred years inevitably blurs our perspective of the man and his intentions. We find ourselves unconsciously reading more into his lines than he possibly meant us to. We are tempted to attach significance to certain words and disregard others, in an arbitrary fashion. We try to reconstruct Molière's attitude towards his contemporaries and theirs to him, from evidence that is often flimsy and seldom reliable. Molière's very identity has been questioned to the extent that the authorship of his plays has been variously attributed to such different personalities as Louis XIV and the great Corneilleo. To these problems is added a further complication when one embarks upon a thesis dealing with the picture of society as it emerges from Molière's plays. Not only are we confronted with the difficulty of interpretation already mentioned, but also with the vastly different way in which pre-enlightenment man regarded social and political institutions. We of the twentieth century tend to take for granted the notions of liberty, fraternity, and equality. Had anyone formulated such ideas in the seventeenth century, it is doubtful whether they would have been accepted, since they contradict the very concept upon which society was based in the age of Louis XIV. This concept, broadly speaking, is that of a strict hierarchy in which everyone has his own appointed place. Obviously the notion of a hierarchy pre-supposes the inferiority of some and the superiority of others in the social structure of the day; and post-enlightenment thinking does not readily accept that some men should be privileged and others regarded as belonging naturally to the lower orders. Intro., p. 1-2.
- Full Text:
- Date Issued: 1974
- Authors: Brooks, Beverley Anne
- Date: 1974
- Subjects: Molière, 1622-1673 -- Criticism and interpretation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3627 , http://hdl.handle.net/10962/d1009758
- Description: It is by no means an easy task to analyse and interpret the work of a dramatist such as Molière, for an interval of three hundred years inevitably blurs our perspective of the man and his intentions. We find ourselves unconsciously reading more into his lines than he possibly meant us to. We are tempted to attach significance to certain words and disregard others, in an arbitrary fashion. We try to reconstruct Molière's attitude towards his contemporaries and theirs to him, from evidence that is often flimsy and seldom reliable. Molière's very identity has been questioned to the extent that the authorship of his plays has been variously attributed to such different personalities as Louis XIV and the great Corneilleo. To these problems is added a further complication when one embarks upon a thesis dealing with the picture of society as it emerges from Molière's plays. Not only are we confronted with the difficulty of interpretation already mentioned, but also with the vastly different way in which pre-enlightenment man regarded social and political institutions. We of the twentieth century tend to take for granted the notions of liberty, fraternity, and equality. Had anyone formulated such ideas in the seventeenth century, it is doubtful whether they would have been accepted, since they contradict the very concept upon which society was based in the age of Louis XIV. This concept, broadly speaking, is that of a strict hierarchy in which everyone has his own appointed place. Obviously the notion of a hierarchy pre-supposes the inferiority of some and the superiority of others in the social structure of the day; and post-enlightenment thinking does not readily accept that some men should be privileged and others regarded as belonging naturally to the lower orders. Intro., p. 1-2.
- Full Text:
- Date Issued: 1974
The economic structure of the Cape Midlands and Karroo Region : a sectoral and spatial survey
- Authors: Blumenfeld, Jesmond P
- Date: 1974
- Subjects: South Africa -- Economic conditions -- 1961-1991 , Regional planning -- South Africa -- Cape Province
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:1066 , http://hdl.handle.net/10962/d1007660 , South Africa -- Economic conditions -- 1961-1991 , Regional planning -- South Africa -- Cape Province
- Description: [The] region, as defined, excludes not only these metropolitan areas themselves but also the inner peripheries of their hinterlands. Thus, virtually all areas within regular (i. e. daily) commuting distance of the metropolitan centres, and all areas into which urban development in the latter might 'spill over' in the foreseeable future are excluded. In the case of Metropolitan Port Elizabeth, these exclusions are reflected in the roughly 'crescent-shaped' southern boundary of the region. The situation of the region can further be described in terms of its major physiographic features which reveal a number of factors which are also of importance for understanding and analysing the economy of the area. Intro., p. 1.
- Full Text:
- Date Issued: 1974
- Authors: Blumenfeld, Jesmond P
- Date: 1974
- Subjects: South Africa -- Economic conditions -- 1961-1991 , Regional planning -- South Africa -- Cape Province
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:1066 , http://hdl.handle.net/10962/d1007660 , South Africa -- Economic conditions -- 1961-1991 , Regional planning -- South Africa -- Cape Province
- Description: [The] region, as defined, excludes not only these metropolitan areas themselves but also the inner peripheries of their hinterlands. Thus, virtually all areas within regular (i. e. daily) commuting distance of the metropolitan centres, and all areas into which urban development in the latter might 'spill over' in the foreseeable future are excluded. In the case of Metropolitan Port Elizabeth, these exclusions are reflected in the roughly 'crescent-shaped' southern boundary of the region. The situation of the region can further be described in terms of its major physiographic features which reveal a number of factors which are also of importance for understanding and analysing the economy of the area. Intro., p. 1.
- Full Text:
- Date Issued: 1974
A study of the burrowing sandprawn Callianassa kraussi Stebbing (Crustacea - Decapoda - Thalassinidea)
- Authors: Forbes, Anthony Tonks
- Date: 1974
- Subjects: Estuarine biology -- South Africa Shrimps -- South Africa Decapoda (Crustacea) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5850 , http://hdl.handle.net/10962/d1011866
- Description: The distribution of Callianassa kraussi in southern Africa extends from Lamberts Bay on the west coast to San Martinho in Mocambique. This represents a northerly extension of the range from the previous known limit of Inhaca Island. In this area 59 localities were visited and records obtained for an additional 16. Three areas were selected for detailed study. These were the west Kleinemonde estuary, which is normally closed off from the sea by a sand bar and the open Swartkops estuary both on the southeastern Cape coast, and the Swartvlei system, which consists of a lake connected to the sea by a channel which closes intermittently, on the southern Cape coast. The nature of the burrows constructed by C. kraussi was investigated in these areas. Burrow complexes may have up to nine entrances but more commonly two to four. Laboratory studies suggest that the number of entrances does not exceed the number of prawns present and consequently burrow opening counts will give an estimate of population density. Water movement can result in the closing off of burrows while strong water and sand movement will exclude C.kraussi from an area. C.kraussi is also excluded from areas which have very coarse substrates. A three year regular sampling program showed that C.kraussi breeds mainly in winter/spring with a smaller breeding peak in summer. Egg development time at 20°C in a salinity of 35° /₀₀ is 30-33 days. There are two larval stages which last 3-5 days. Development time of the eggs is tripled at temperatures of 13-15°C while larval development time is extended to 9-14 days. Development is possibly slightly accelerated at 25 ± 3°C but the number of eggs hatching is markedly reduced. Larval development times were similar to those at 20° and 35°/₀₀. There are no planktonic larval stages. Growth was more rapid and greater size was attained in the open Swartkops estuary than in the closed Kleinemonde estuary. Prawns hatching in winter/spring breed for the first time in the following summer at an age of about 16 months and then again in the following winter/spring at an age of about 2 years. Prawns hatching in summer breed in the following winter at an age of about 18 months and then again in the immediately following summer. Longevity in both sexes is about 2 years. Dispersal is accomplished by migration of the post-larval juvenile phases at an age of 3-5 months. Non-selfmaintaining populations exist in areas where salinities are too low to permit breeding. Population densities were found to vary markedly in different areas. Investigations of osmotic and ionic regulation showed that C.kraussi is a strong hyper-regulator and thus distinct from any other known species in the genus. Volume regulatory ability is well developed and depends on variable rates of urine production. Salt loss in dilutions occurs almost equally via the gills and the urine. The general responses of C.kraussi to dilutions of sea water are discussed. Various suggestions for conservation measures based on the distribution and iife cycle of C.kraussi were made. The factors affecting the distribution of C.kraussi are discussed. The problem of the larval development in C.kraussi was discussed in relation to reviews of larval types of benthic invertebrates. The importance of the burrow, the possible route by which C.kraussi has invaded estuaries and the differences between open and closed estuaries as shown by the effects on C.kraussi were discussed.
- Full Text:
- Date Issued: 1974
- Authors: Forbes, Anthony Tonks
- Date: 1974
- Subjects: Estuarine biology -- South Africa Shrimps -- South Africa Decapoda (Crustacea) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5850 , http://hdl.handle.net/10962/d1011866
- Description: The distribution of Callianassa kraussi in southern Africa extends from Lamberts Bay on the west coast to San Martinho in Mocambique. This represents a northerly extension of the range from the previous known limit of Inhaca Island. In this area 59 localities were visited and records obtained for an additional 16. Three areas were selected for detailed study. These were the west Kleinemonde estuary, which is normally closed off from the sea by a sand bar and the open Swartkops estuary both on the southeastern Cape coast, and the Swartvlei system, which consists of a lake connected to the sea by a channel which closes intermittently, on the southern Cape coast. The nature of the burrows constructed by C. kraussi was investigated in these areas. Burrow complexes may have up to nine entrances but more commonly two to four. Laboratory studies suggest that the number of entrances does not exceed the number of prawns present and consequently burrow opening counts will give an estimate of population density. Water movement can result in the closing off of burrows while strong water and sand movement will exclude C.kraussi from an area. C.kraussi is also excluded from areas which have very coarse substrates. A three year regular sampling program showed that C.kraussi breeds mainly in winter/spring with a smaller breeding peak in summer. Egg development time at 20°C in a salinity of 35° /₀₀ is 30-33 days. There are two larval stages which last 3-5 days. Development time of the eggs is tripled at temperatures of 13-15°C while larval development time is extended to 9-14 days. Development is possibly slightly accelerated at 25 ± 3°C but the number of eggs hatching is markedly reduced. Larval development times were similar to those at 20° and 35°/₀₀. There are no planktonic larval stages. Growth was more rapid and greater size was attained in the open Swartkops estuary than in the closed Kleinemonde estuary. Prawns hatching in winter/spring breed for the first time in the following summer at an age of about 16 months and then again in the following winter/spring at an age of about 2 years. Prawns hatching in summer breed in the following winter at an age of about 18 months and then again in the immediately following summer. Longevity in both sexes is about 2 years. Dispersal is accomplished by migration of the post-larval juvenile phases at an age of 3-5 months. Non-selfmaintaining populations exist in areas where salinities are too low to permit breeding. Population densities were found to vary markedly in different areas. Investigations of osmotic and ionic regulation showed that C.kraussi is a strong hyper-regulator and thus distinct from any other known species in the genus. Volume regulatory ability is well developed and depends on variable rates of urine production. Salt loss in dilutions occurs almost equally via the gills and the urine. The general responses of C.kraussi to dilutions of sea water are discussed. Various suggestions for conservation measures based on the distribution and iife cycle of C.kraussi were made. The factors affecting the distribution of C.kraussi are discussed. The problem of the larval development in C.kraussi was discussed in relation to reviews of larval types of benthic invertebrates. The importance of the burrow, the possible route by which C.kraussi has invaded estuaries and the differences between open and closed estuaries as shown by the effects on C.kraussi were discussed.
- Full Text:
- Date Issued: 1974
The Aapiesboomen magnesite deposit, Burgersfort, Transvaal
- Authors: Taylor, N C
- Date: 1974
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21130 , http://hdl.handle.net/10962/6505
- Description: The published literature on magnesite is extensively reviewed as regards the properties, uses, production, occurrence and genesis of the mineral. Despite opposition from the producers of sea water magnesia in recent years, magnesite still finds a ready market for the manufacture of refractory materials, particularly in the steel industry. Less important uses include the manufacture of magnesium metal, carbonic acid gas, Sorel cement, paper, pharmaceuticals and fertilizers. Large bodies of cryptocrystalline magnesite occur in Greece, Yugoslavia, Turkey and India, while the deposits in Austria, Czechoslovakia, Russia and China produce most of the world supply of crystalline material. Four types of magnesite bodies may be distinguished: quartz-magnesite deposits, talc-magnesite occurrences, magnesite associated with sedimentary rocks and sagvandite, a magnesite-bronzite rock. Most South African deposits, including the Aapiesboomen body, belong to the first type. Experimental, field and textural evidence indicates that the quartz-magnesite deposits may form from serpentine under a wide range of hydrothermal and supergene conditions below about 400°C and between very low and very high concentrations of co2 in the fluid phase. Above 400°C talc is produced at the expense of quartz. Sedimentary magnesite has been observed t o form in present day saline lakes, but the large size of the older crystalline deposits associated with limestones and dolomites has been used as an argument against the use of the same principle to explain the genesis of the latter bodies : much controversy still surrounds the sedimentary-hydrothermal debate concerning their origin. It seems probable thet sagvandites are produced by a process of CO2- metasomatism.
- Full Text:
- Date Issued: 1974
- Authors: Taylor, N C
- Date: 1974
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21130 , http://hdl.handle.net/10962/6505
- Description: The published literature on magnesite is extensively reviewed as regards the properties, uses, production, occurrence and genesis of the mineral. Despite opposition from the producers of sea water magnesia in recent years, magnesite still finds a ready market for the manufacture of refractory materials, particularly in the steel industry. Less important uses include the manufacture of magnesium metal, carbonic acid gas, Sorel cement, paper, pharmaceuticals and fertilizers. Large bodies of cryptocrystalline magnesite occur in Greece, Yugoslavia, Turkey and India, while the deposits in Austria, Czechoslovakia, Russia and China produce most of the world supply of crystalline material. Four types of magnesite bodies may be distinguished: quartz-magnesite deposits, talc-magnesite occurrences, magnesite associated with sedimentary rocks and sagvandite, a magnesite-bronzite rock. Most South African deposits, including the Aapiesboomen body, belong to the first type. Experimental, field and textural evidence indicates that the quartz-magnesite deposits may form from serpentine under a wide range of hydrothermal and supergene conditions below about 400°C and between very low and very high concentrations of co2 in the fluid phase. Above 400°C talc is produced at the expense of quartz. Sedimentary magnesite has been observed t o form in present day saline lakes, but the large size of the older crystalline deposits associated with limestones and dolomites has been used as an argument against the use of the same principle to explain the genesis of the latter bodies : much controversy still surrounds the sedimentary-hydrothermal debate concerning their origin. It seems probable thet sagvandites are produced by a process of CO2- metasomatism.
- Full Text:
- Date Issued: 1974
A share in pain and passion: the women of Synge's plays
- Authors: Finn, Stephen Michael
- Date: 1974
- Subjects: Synge, J. M. (John Millington), 1871-1909 , English literature -- Irish authors -- History and criticism , English drama -- Irish authors -- History and criticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2295 , http://hdl.handle.net/10962/d1011865 , Synge, J. M. (John Millington), 1871-1909 , English literature -- Irish authors -- History and criticism , English drama -- Irish authors -- History and criticism
- Description: Synge's plays contain some of the most arresting figures in modern drama, his characterization second only to his unique language, the most striking feature of his writing. Of the men, only Christy Mahon and Martin Doul stand out but the women form a brilliant company usually overshadowing the other characters. Chapter 1, p. 1.
- Full Text:
- Date Issued: 1974
- Authors: Finn, Stephen Michael
- Date: 1974
- Subjects: Synge, J. M. (John Millington), 1871-1909 , English literature -- Irish authors -- History and criticism , English drama -- Irish authors -- History and criticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2295 , http://hdl.handle.net/10962/d1011865 , Synge, J. M. (John Millington), 1871-1909 , English literature -- Irish authors -- History and criticism , English drama -- Irish authors -- History and criticism
- Description: Synge's plays contain some of the most arresting figures in modern drama, his characterization second only to his unique language, the most striking feature of his writing. Of the men, only Christy Mahon and Martin Doul stand out but the women form a brilliant company usually overshadowing the other characters. Chapter 1, p. 1.
- Full Text:
- Date Issued: 1974
A contribution to the biology of Pseudodiaptomus hessei (Mrázek) (Copepoda : Calanoida) in Lake Sibaya, South Africa
- Authors: Hart, Robert Clynton
- Date: 1974
- Subjects: Copepoda -- South Africa Freshwater biology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5854 , http://hdl.handle.net/10962/d1012210
- Description: Aspects of the biology of the calanoid copepod Pseudodiaptomus hessei are described, with particular reference to its vertical migratory behaviour. The present investigations were carried out largely by means of Nansen-type plankton nets, but several new pieces of apparatus were developed and. are described herein. The daytime vertical distribution of P. hessei varies according to developmental stage and depth of water. In shallow areas of the lake the entire population is benthic or in very close association with the lake bed. In the deepest part of the lake (40m) the naupliar and early (i.e. C I - C III) copepodite stages are essentially pelagic, but the adult and late (i.e. C IV - C V) copepodite stages are predominantly benthic and may be quiescent or infaunal. During the hours of darkness, the calanoids are distributed through the water column. The nauplii are consistently abundant in the surface waters but the distribution of the other stages is not regular. The distribution can be related to lunar intensity in many cases, with the post-naupliar stages frequently occurring deeper in the water column on bright moonlight nights and in the surface waters on overcast moolnless nights. The dusk ascent and dawn descent of the calenoids is clearly related to changes in light penetration in most individuals. The movements of a fraction of the adults occur in the apparent absence of adequate light cues. This behaviour is shown more extensively by the adult females. An endogenous activity rhythm has been shown in the species under laboratory conditions and it is suggested that this may play a part in the migratory movements. A basic examination of the feeding methods, feeding appendages and food sources of adult and late copepodite stages has been made. Changes in feeding intensity through twenty-four have been examined in the field and under laboratory conditions. Using as an index of feeding intensity, the proportion of animals with food in their guts, it has been shown that a pronounced diel difference occurs in adult calanoids in the lake. Feeding is almost entirely restricted to the nocturnal presence of the calanoids in the water coloumn. This difference exists in the pre-adult copepodite stages, but is not nearly as striking. The absence of feeding during daylight is not readily accounted for in terms of food availability and it is attributed to the quiescent or possible infaunal existence of the adults. A periodicity in egg hatching has been shown Naupliar release from the parental egg sac is predominantly a nocturnal phenomenon in the hot and cool seasons. It is suggested that this may be important in attaining a favourable vertical distritution for the nauplii, and may be important in the distribution of the species. A preliminary acccunt of the seasonal cycle and population dynamics of P. hessei is given, based on data collected over two years at a single station. Seasonal changes in calanoid abundance are intermediate between those recorded in truly tropical areas and in temperate latitudes. Potential food sources show relatively little change. The vertical migration of P. hessei is considered in relation to its apparent ecological significance and comparisons are drawn with observations made on the same species or other pseudodiaptomids in estuaries and lagoons elsewhere.
- Full Text:
- Date Issued: 1974
- Authors: Hart, Robert Clynton
- Date: 1974
- Subjects: Copepoda -- South Africa Freshwater biology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5854 , http://hdl.handle.net/10962/d1012210
- Description: Aspects of the biology of the calanoid copepod Pseudodiaptomus hessei are described, with particular reference to its vertical migratory behaviour. The present investigations were carried out largely by means of Nansen-type plankton nets, but several new pieces of apparatus were developed and. are described herein. The daytime vertical distribution of P. hessei varies according to developmental stage and depth of water. In shallow areas of the lake the entire population is benthic or in very close association with the lake bed. In the deepest part of the lake (40m) the naupliar and early (i.e. C I - C III) copepodite stages are essentially pelagic, but the adult and late (i.e. C IV - C V) copepodite stages are predominantly benthic and may be quiescent or infaunal. During the hours of darkness, the calanoids are distributed through the water column. The nauplii are consistently abundant in the surface waters but the distribution of the other stages is not regular. The distribution can be related to lunar intensity in many cases, with the post-naupliar stages frequently occurring deeper in the water column on bright moonlight nights and in the surface waters on overcast moolnless nights. The dusk ascent and dawn descent of the calenoids is clearly related to changes in light penetration in most individuals. The movements of a fraction of the adults occur in the apparent absence of adequate light cues. This behaviour is shown more extensively by the adult females. An endogenous activity rhythm has been shown in the species under laboratory conditions and it is suggested that this may play a part in the migratory movements. A basic examination of the feeding methods, feeding appendages and food sources of adult and late copepodite stages has been made. Changes in feeding intensity through twenty-four have been examined in the field and under laboratory conditions. Using as an index of feeding intensity, the proportion of animals with food in their guts, it has been shown that a pronounced diel difference occurs in adult calanoids in the lake. Feeding is almost entirely restricted to the nocturnal presence of the calanoids in the water coloumn. This difference exists in the pre-adult copepodite stages, but is not nearly as striking. The absence of feeding during daylight is not readily accounted for in terms of food availability and it is attributed to the quiescent or possible infaunal existence of the adults. A periodicity in egg hatching has been shown Naupliar release from the parental egg sac is predominantly a nocturnal phenomenon in the hot and cool seasons. It is suggested that this may be important in attaining a favourable vertical distritution for the nauplii, and may be important in the distribution of the species. A preliminary acccunt of the seasonal cycle and population dynamics of P. hessei is given, based on data collected over two years at a single station. Seasonal changes in calanoid abundance are intermediate between those recorded in truly tropical areas and in temperate latitudes. Potential food sources show relatively little change. The vertical migration of P. hessei is considered in relation to its apparent ecological significance and comparisons are drawn with observations made on the same species or other pseudodiaptomids in estuaries and lagoons elsewhere.
- Full Text:
- Date Issued: 1974