A contribution to a generic revision of Simochromis and Tropheus (Pisces : Cichlidae) - from Lake Tanganyika, with special reference to the Pharyngeal Apophysis and its taxonomic importance
- Authors: Axelrod, Glen S
- Date: 1978
- Subjects: Cichlids -- Tanganyika, Lake
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5349 , http://hdl.handle.net/10962/d1007510 , Cichlids -- Tanganyika, Lake
- Description: The purpose of this thesis is to investigate the taxonomic status of Simochromis and Tropheue. Material for the study wae collected during three visits to Lake Tanganyika in 1976-1977. Tropheus polli G. S . Axelrod 1977, was found and described, and a new species of Simochromis was found and will be described in a forthcoming paper. Nine colour varieties of Tropheus maorii and three colour varieties of Tropheus duboisi were found and described. A diagnosis and description, with colour photographs, is given using morphometries and meristics of the five species of Simochromis and four species of Tropheus. A dissection and cleaning technique tor the pharyngeal apophysis and lower pharyngeal bone is explained, together with a method for the interpretation of relative bone composition of the pharyngeal apophysis. Photographs are included. The dentition is examined, evaluated and figured. Doubt has been cast upon the taxonomic validity of the composition of the pharyngeal apophysis as an indicator of affinity at the sub familial level. This is shown by its seeming lack of functional relationship, apparent arbitrary variation, interspecific variability in Simochromis and Tropheus, and intraspecific variability in S. diagramma and T. duboisi. Thus, the apophysis cannot be considered a reliable cichlid taxonomic characteristic at any level of classification, unless its validity is Substantiated in each instance. Furthermore, it is considered very probable that the Tropheus-Simochromis species complex is a monophyletic assemblage at the genus level, on the basis of similar dentition and mouth form, which is unique in Lake Tanganyika. It is proposed on phyletic grounds that Simochromis and Tropheus be united into the one genus Tropheus, and that Tropheus be divided into the subgenera , Tropheus (Tropheus) and Tropheus (Simochromis), along the lines of its previous division in two separate genera. Characteristics supporting this division include differences in the anal and dorsal fin meristic counts noted in the original descriptions of the genera. In addition, two modifications of the dentition were found during the course of this study which are not mentioned in any previous literature. It is considered probable, that Tropheus (Tropheus) and Tropheus (Simochromis) are monophyletic sister groups within the Tropheus complex. Pseudosimochromis Nelissen 1977 is not considered to be a taxonomically valid genus on either phyletic or gradistic grounds, and is included within Tropheus (Simochromis). The lower pharyngeal bone of T . (S.) diagramma is considered to be plesiomorphic in tooth arrangement, size and shape. A preliminary worKing hypothesis is established on the basis of the conjectures made and other available information which supports the phyletic relationship suggested by Fryer and lIes (1972). An illustration is given.
- Full Text:
- Date Issued: 1978
- Authors: Axelrod, Glen S
- Date: 1978
- Subjects: Cichlids -- Tanganyika, Lake
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5349 , http://hdl.handle.net/10962/d1007510 , Cichlids -- Tanganyika, Lake
- Description: The purpose of this thesis is to investigate the taxonomic status of Simochromis and Tropheue. Material for the study wae collected during three visits to Lake Tanganyika in 1976-1977. Tropheus polli G. S . Axelrod 1977, was found and described, and a new species of Simochromis was found and will be described in a forthcoming paper. Nine colour varieties of Tropheus maorii and three colour varieties of Tropheus duboisi were found and described. A diagnosis and description, with colour photographs, is given using morphometries and meristics of the five species of Simochromis and four species of Tropheus. A dissection and cleaning technique tor the pharyngeal apophysis and lower pharyngeal bone is explained, together with a method for the interpretation of relative bone composition of the pharyngeal apophysis. Photographs are included. The dentition is examined, evaluated and figured. Doubt has been cast upon the taxonomic validity of the composition of the pharyngeal apophysis as an indicator of affinity at the sub familial level. This is shown by its seeming lack of functional relationship, apparent arbitrary variation, interspecific variability in Simochromis and Tropheus, and intraspecific variability in S. diagramma and T. duboisi. Thus, the apophysis cannot be considered a reliable cichlid taxonomic characteristic at any level of classification, unless its validity is Substantiated in each instance. Furthermore, it is considered very probable that the Tropheus-Simochromis species complex is a monophyletic assemblage at the genus level, on the basis of similar dentition and mouth form, which is unique in Lake Tanganyika. It is proposed on phyletic grounds that Simochromis and Tropheus be united into the one genus Tropheus, and that Tropheus be divided into the subgenera , Tropheus (Tropheus) and Tropheus (Simochromis), along the lines of its previous division in two separate genera. Characteristics supporting this division include differences in the anal and dorsal fin meristic counts noted in the original descriptions of the genera. In addition, two modifications of the dentition were found during the course of this study which are not mentioned in any previous literature. It is considered probable, that Tropheus (Tropheus) and Tropheus (Simochromis) are monophyletic sister groups within the Tropheus complex. Pseudosimochromis Nelissen 1977 is not considered to be a taxonomically valid genus on either phyletic or gradistic grounds, and is included within Tropheus (Simochromis). The lower pharyngeal bone of T . (S.) diagramma is considered to be plesiomorphic in tooth arrangement, size and shape. A preliminary worKing hypothesis is established on the basis of the conjectures made and other available information which supports the phyletic relationship suggested by Fryer and lIes (1972). An illustration is given.
- Full Text:
- Date Issued: 1978
A contribution to the petrology of kimberlites
- Authors: Kruger, Floris Johan
- Date: 1978 , 2013-10-17
- Subjects: Kimberlite -- Africa, Southern , Petrology , Igneous rocks -- Inclusions
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5024 , http://hdl.handle.net/10962/d1006886 , Kimberlite -- Africa, Southern , Petrology , Igneous rocks -- Inclusions
- Description: The petrogenetic relationships of the different varieties of kimberlite in the De Beers Mine and Letseng-Ia-terai composite diatremes have been investigated using petrographic and chemical methods. Kimberlites in the Letseng-Ia-terai diatreme were found to be strongly contaminated by crustal material, mainly basalt. A method to correct for the effects of the contamination has been developed and applied to these kimberlites. Using the corrected data, the four kimberlite types in each group appear to be related to each other by crystal/liquid fractionation models. However the two groups cannot be related to each other. The De Beer Mine has two varieties of kimberlite, a monticellite apatite and calcite rich variety which intruded first, and a phlogopite rich type forming a discrete cylindrical body within the earlier kimberlite. These two kimberlites do not appear to be related by any of the fractionation models discussed. An examination of the data from this work and published sources, suggests that kimberlites are derived from below the low velocity zone by small degrees of partial melting involving garnet lherzolite with subordinate phlogopite and carbonate. Diamonds are probably incorporated as xenocrysts in the magma. Upward movement and emplacement of kimberlite appears to have been very rapid. The diatremes were probably eroded and shaped by gas, derived from the kimberlite magma, escaping to surface along weak zones in the earth's crust. Xenoliths of crustal material incorporated in the kimberlite on intrusion have also been studied and various features due to alteration by the magma are described, including the formation of natrolite and cebollite. The latter is a rare mineral that has not been described from kimberlite before. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1978
- Authors: Kruger, Floris Johan
- Date: 1978 , 2013-10-17
- Subjects: Kimberlite -- Africa, Southern , Petrology , Igneous rocks -- Inclusions
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5024 , http://hdl.handle.net/10962/d1006886 , Kimberlite -- Africa, Southern , Petrology , Igneous rocks -- Inclusions
- Description: The petrogenetic relationships of the different varieties of kimberlite in the De Beers Mine and Letseng-Ia-terai composite diatremes have been investigated using petrographic and chemical methods. Kimberlites in the Letseng-Ia-terai diatreme were found to be strongly contaminated by crustal material, mainly basalt. A method to correct for the effects of the contamination has been developed and applied to these kimberlites. Using the corrected data, the four kimberlite types in each group appear to be related to each other by crystal/liquid fractionation models. However the two groups cannot be related to each other. The De Beer Mine has two varieties of kimberlite, a monticellite apatite and calcite rich variety which intruded first, and a phlogopite rich type forming a discrete cylindrical body within the earlier kimberlite. These two kimberlites do not appear to be related by any of the fractionation models discussed. An examination of the data from this work and published sources, suggests that kimberlites are derived from below the low velocity zone by small degrees of partial melting involving garnet lherzolite with subordinate phlogopite and carbonate. Diamonds are probably incorporated as xenocrysts in the magma. Upward movement and emplacement of kimberlite appears to have been very rapid. The diatremes were probably eroded and shaped by gas, derived from the kimberlite magma, escaping to surface along weak zones in the earth's crust. Xenoliths of crustal material incorporated in the kimberlite on intrusion have also been studied and various features due to alteration by the magma are described, including the formation of natrolite and cebollite. The latter is a rare mineral that has not been described from kimberlite before. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1978
An investigation into the effect of particulate solids on certain antimicrobial preservatives in pharmaceutical and cosmetic suspensions
- Authors: Horn, Norman Robert
- Date: 1978
- Subjects: Drugs -- Preservation , Drugs -- Microbiology , Cosmetics -- Preservation , Cosmetics -- Microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3848 , http://hdl.handle.net/10962/d1012436 , Drugs -- Preservation , Drugs -- Microbiology , Cosmetics -- Preservation , Cosmetics -- Microbiology
- Description: Pharmaceutical and cosmetic preparations must be formulated so as to assure elegance of appearance, efficacy of ingredients and a satisfactory shelf life as the product. If the formulation is not self-preserving and if it contains material which could act as a substrate for growth of micro-organisms, the shelf life aspect involves, in addition to several other factors, the choice of a suitable antimicrobial preservative. Such preservatives, when present in the minimum effective concentration, are unfortunately prone to interact with many other materials. A number of papers on the inactivation of preservatives by containers, filters and formulation components have been published. The field has been adequately reviewed by de Navarre (1962), Wedderburn (1964) and, more recently, by Coates (1973). From these reviews and from a study of the literature it became apparent that relatively little work had been done on interactions between preservatives and solid particles in aqueous suspension. Consequently, a range of preservatives not previously investigated in this respect was tested for loss of activity in the presence of fifteen powders commonly used in aqueous suspension in pharmaceutical and cosmetic formulations. In view of the information obtained in this preliminary study and after the development of more satisfactory analytical techniques it was decided to study in greater depth the interaction between these powders and selected organomercurials and quaternary ammonium compounds.
- Full Text:
- Date Issued: 1978
- Authors: Horn, Norman Robert
- Date: 1978
- Subjects: Drugs -- Preservation , Drugs -- Microbiology , Cosmetics -- Preservation , Cosmetics -- Microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3848 , http://hdl.handle.net/10962/d1012436 , Drugs -- Preservation , Drugs -- Microbiology , Cosmetics -- Preservation , Cosmetics -- Microbiology
- Description: Pharmaceutical and cosmetic preparations must be formulated so as to assure elegance of appearance, efficacy of ingredients and a satisfactory shelf life as the product. If the formulation is not self-preserving and if it contains material which could act as a substrate for growth of micro-organisms, the shelf life aspect involves, in addition to several other factors, the choice of a suitable antimicrobial preservative. Such preservatives, when present in the minimum effective concentration, are unfortunately prone to interact with many other materials. A number of papers on the inactivation of preservatives by containers, filters and formulation components have been published. The field has been adequately reviewed by de Navarre (1962), Wedderburn (1964) and, more recently, by Coates (1973). From these reviews and from a study of the literature it became apparent that relatively little work had been done on interactions between preservatives and solid particles in aqueous suspension. Consequently, a range of preservatives not previously investigated in this respect was tested for loss of activity in the presence of fifteen powders commonly used in aqueous suspension in pharmaceutical and cosmetic formulations. In view of the information obtained in this preliminary study and after the development of more satisfactory analytical techniques it was decided to study in greater depth the interaction between these powders and selected organomercurials and quaternary ammonium compounds.
- Full Text:
- Date Issued: 1978
Aspects of the bioavailability of topical corticosteroid formulations
- Authors: Magnus, Ashley Denis
- Date: 2013-02-12
- Subjects: Adrenocortical hormones -- Therapeutic use , Dermatologic agents , Transdermal medication -- Evaluation , Dermatopharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3843 , http://hdl.handle.net/10962/d1009516 , Adrenocortical hormones -- Therapeutic use , Dermatologic agents , Transdermal medication -- Evaluation , Dermatopharmacology
- Description: Two possible variables of the McKenzie/Stoughton blanching assay, namely amount applied to the test site and occlusion time have been investigated. Subsequently, two topical steroid preparations, Synalar cream (0,025% fluocinolone acetonide) and Betnovate cream (0,1% betamethasone 17-valer ate) were extemporaneously diluted with five and six placebo bases respectively. Taking cognizance of the two possible variables, these diluted preparations were assessed in vivo using a modified version of the McKenzie/Stoughton blanching assay for blanching activity over a 14 month period. It was found that the base E45, which is slightly alkali, had the greatest effect on both preparations. In the case of betamethasone 17-valerate this base c aused the conversion to the less active isomer, betamethasone 21-valerate whereas at the end of the 14 month test period it was found that the Synalar/E45 dilution contained no fluocinolone acetonide. Quantitative analysis of all the diluted preparations by high performance liquid chromatography using a reverse-phase system was performed. The data obtained f r om the systematic stUdies of the effects of varying concentrations and occlusion times were presented at the Eleventh National Congress of the South African Pharmacological Society. , KMBT_363 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Authors: Magnus, Ashley Denis
- Date: 2013-02-12
- Subjects: Adrenocortical hormones -- Therapeutic use , Dermatologic agents , Transdermal medication -- Evaluation , Dermatopharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3843 , http://hdl.handle.net/10962/d1009516 , Adrenocortical hormones -- Therapeutic use , Dermatologic agents , Transdermal medication -- Evaluation , Dermatopharmacology
- Description: Two possible variables of the McKenzie/Stoughton blanching assay, namely amount applied to the test site and occlusion time have been investigated. Subsequently, two topical steroid preparations, Synalar cream (0,025% fluocinolone acetonide) and Betnovate cream (0,1% betamethasone 17-valer ate) were extemporaneously diluted with five and six placebo bases respectively. Taking cognizance of the two possible variables, these diluted preparations were assessed in vivo using a modified version of the McKenzie/Stoughton blanching assay for blanching activity over a 14 month period. It was found that the base E45, which is slightly alkali, had the greatest effect on both preparations. In the case of betamethasone 17-valerate this base c aused the conversion to the less active isomer, betamethasone 21-valerate whereas at the end of the 14 month test period it was found that the Synalar/E45 dilution contained no fluocinolone acetonide. Quantitative analysis of all the diluted preparations by high performance liquid chromatography using a reverse-phase system was performed. The data obtained f r om the systematic stUdies of the effects of varying concentrations and occlusion times were presented at the Eleventh National Congress of the South African Pharmacological Society. , KMBT_363 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
Bacterial degradation of ixodicide amitraz
- Authors: Allcock, Errol Ralph
- Date: 1978
- Subjects: Ticks -- Control , Pesticides -- Biodegradation , Acaricides
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4081 , http://hdl.handle.net/10962/d1007473 , Ticks -- Control , Pesticides -- Biodegradation , Acaricides
- Description: The control of ticks on cattle has long been a matter of prime importance to stock owners over most of the intensive natural grazing areas in the Southern Hemisphere. The only practical method of dealing with the cattle tick problem in the short term is by treating the infected bovine host with ixodicides i. e. by chemical control. This can be achieved by either plunging the cattle into a dip tank containing aqueous suspensions or emulsions of the ixodicide or by spraying them with dip suspensions in a spray race.
- Full Text:
- Date Issued: 1978
- Authors: Allcock, Errol Ralph
- Date: 1978
- Subjects: Ticks -- Control , Pesticides -- Biodegradation , Acaricides
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4081 , http://hdl.handle.net/10962/d1007473 , Ticks -- Control , Pesticides -- Biodegradation , Acaricides
- Description: The control of ticks on cattle has long been a matter of prime importance to stock owners over most of the intensive natural grazing areas in the Southern Hemisphere. The only practical method of dealing with the cattle tick problem in the short term is by treating the infected bovine host with ixodicides i. e. by chemical control. This can be achieved by either plunging the cattle into a dip tank containing aqueous suspensions or emulsions of the ixodicide or by spraying them with dip suspensions in a spray race.
- Full Text:
- Date Issued: 1978
Community metabolism and phosphorus dynamics in a seasonally closed South African estuary
- Liptrot, Mark Robert Michael
- Authors: Liptrot, Mark Robert Michael
- Date: 1978
- Subjects: Estuarine ecology -- Research -- South Africa -- Swartvlei , Eelgrass -- Research -- South Africa , Enteromorpha -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5810 , http://hdl.handle.net/10962/d1006966 , Estuarine ecology -- Research -- South Africa -- Swartvlei , Eelgrass -- Research -- South Africa , Enteromorpha -- Research -- South Africa
- Description: The effects of seawater inflows and macrophyte beds on community metabolism and phosphorus dynamics in the seasonally-closed Swartvlei estuary were investigated. Metabolic rates were determined by diurnal oxygen curve analysis. Gross primary production ranged from 0,7 to 14,9 g 0₂ m⁻² day⁻¹, and respiration from 0,9 to 25,2 g 0₂ m⁻² day⁻¹. The highest production rates were recorded inside the dense beds of Zostera capens is Setchell (x- = 7,8 g 0₂ m⁻² day⁻¹ ). Metabolism was positively correlated to submersed macrophyte cover, and decreased upstream of the mouth region. No seasonal variation in gross production could be detected, and mouth closure had no detectable effect on metabolic rates. Growth of the green alga Enteromorpha sp. in winter, and the effect of decay of this alga on dissolved oxygen, total inorganic carbon and total dissolved phosphorus in the water column is discussed. High day-time respiration values, measured in a darkened polythene enclosure, indicate that photorespiration occurs in Zostera. Apparently the annual amount of oxygen respired throughout the estuary exceeded that produced by 2 7100 tonnes, i.e. the estuary was heterotrophic. This is discussed in relation to the effectiveness of the diurnal curve method as a way of measuring metabolic rates, and to the possibility of organic matter input via river inflows. There is a net gain of up to 17,4 kg of particulate phosphorus over mean tides. Diurnal phosphorus studies indicate that Zostera releases phosphate into the water column in the light. Enteromorpha takes up phosphate in the morning, which it appears to release over the rest of the day. The cycling of phosphorus between seawater, sediments, macrophytes and the water column is discussed.
- Full Text:
- Date Issued: 1978
- Authors: Liptrot, Mark Robert Michael
- Date: 1978
- Subjects: Estuarine ecology -- Research -- South Africa -- Swartvlei , Eelgrass -- Research -- South Africa , Enteromorpha -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5810 , http://hdl.handle.net/10962/d1006966 , Estuarine ecology -- Research -- South Africa -- Swartvlei , Eelgrass -- Research -- South Africa , Enteromorpha -- Research -- South Africa
- Description: The effects of seawater inflows and macrophyte beds on community metabolism and phosphorus dynamics in the seasonally-closed Swartvlei estuary were investigated. Metabolic rates were determined by diurnal oxygen curve analysis. Gross primary production ranged from 0,7 to 14,9 g 0₂ m⁻² day⁻¹, and respiration from 0,9 to 25,2 g 0₂ m⁻² day⁻¹. The highest production rates were recorded inside the dense beds of Zostera capens is Setchell (x- = 7,8 g 0₂ m⁻² day⁻¹ ). Metabolism was positively correlated to submersed macrophyte cover, and decreased upstream of the mouth region. No seasonal variation in gross production could be detected, and mouth closure had no detectable effect on metabolic rates. Growth of the green alga Enteromorpha sp. in winter, and the effect of decay of this alga on dissolved oxygen, total inorganic carbon and total dissolved phosphorus in the water column is discussed. High day-time respiration values, measured in a darkened polythene enclosure, indicate that photorespiration occurs in Zostera. Apparently the annual amount of oxygen respired throughout the estuary exceeded that produced by 2 7100 tonnes, i.e. the estuary was heterotrophic. This is discussed in relation to the effectiveness of the diurnal curve method as a way of measuring metabolic rates, and to the possibility of organic matter input via river inflows. There is a net gain of up to 17,4 kg of particulate phosphorus over mean tides. Diurnal phosphorus studies indicate that Zostera releases phosphate into the water column in the light. Enteromorpha takes up phosphate in the morning, which it appears to release over the rest of the day. The cycling of phosphorus between seawater, sediments, macrophytes and the water column is discussed.
- Full Text:
- Date Issued: 1978
Geology of part of the central Damara belt around the Tumas River, South West Africa
- Authors: Bunting, F J L
- Date: 1978
- Subjects: Geology -- Namibia -- Damaraland , Geology, Stratigraphic -- Namibia , Geology -- Namibia -- Tumas River Watershed , Geology -- Namibia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5049 , http://hdl.handle.net/10962/d1009957 , Geology -- Namibia -- Damaraland , Geology, Stratigraphic -- Namibia , Geology -- Namibia -- Tumas River Watershed , Geology -- Namibia
- Description: The investigation covering 1500 square kilometres within the central granite zone of the Damara belt, South West Africa, revealed Pre - Damara (Abbabis) basement unconformably overlain by metasediments of the Damara Supergroup. The term Leeukop member is proposed for basal metaconglomerates of the Nosib Group that immediately overlie the basement augen-gneisses. Augen-gneiss clasts are present within the Leeukop metaconglomerates. The Damara orogeny has only partly affected the Abbabis rocks of the Tumas River Inlier but further to the west the Husab suite of red granites and granite-gneisses, as field and geochemical evidence suggest, were derived syntectonically during the Damara orogeny by reactivation of the pre- Damara basement. Rõssing alaskitic granites represent late stage melts, that were also derived from Pre- Damara basement rocks during orogenesis, which accumulated post-tectonically in structural traps at the base of the Khomas Subgroup. Salem granitoids are present in synclinal structures associated with metasediments of the Khomas Subgroup and syntectonic derivation by anatexis during the Damara orogeny is suggested. In the east the differentiated Gawib granitoid stock was emplaced post- tectonically through basement rocks into the Damara metasediments. A deep seated origin is indicated by high crystallisation temperatures (>8500°) obtained from quarternary Qz-An-Ab-Or- H₂0 plots. The metamorphic grade increases westwards from medium grade to high grade. In the east, the metapelites contain andalusite, and coexisting muscovite and quartz. This indicates that temperatures of 6000° at 3,5- 4 kb pressure were attained. In the west, coexisting wollastonite and anorthite in the Khan gneisses indicate pressure- temperature conditions of 720° at 4,5-5 kb. Two tectonic events were responsible for the regional structure. An early F₁ episode produced east- west oriented overturned folds and was followed by an intense F₂ episode of isoclinal folding which is responsible for the dominant northeast - southwest regional fabric. The interference of these folds in the proximity of the underlying basement produced the complex dome and basin structures seen in the central and western parts of the area. An F₃ episode of minor importance was also recognized. The presence of continental basement rocks in this central part of the Damara belt is evidence for formation of the orogen by in-situ deformation rather than continental collision.
- Full Text:
- Date Issued: 1978
- Authors: Bunting, F J L
- Date: 1978
- Subjects: Geology -- Namibia -- Damaraland , Geology, Stratigraphic -- Namibia , Geology -- Namibia -- Tumas River Watershed , Geology -- Namibia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5049 , http://hdl.handle.net/10962/d1009957 , Geology -- Namibia -- Damaraland , Geology, Stratigraphic -- Namibia , Geology -- Namibia -- Tumas River Watershed , Geology -- Namibia
- Description: The investigation covering 1500 square kilometres within the central granite zone of the Damara belt, South West Africa, revealed Pre - Damara (Abbabis) basement unconformably overlain by metasediments of the Damara Supergroup. The term Leeukop member is proposed for basal metaconglomerates of the Nosib Group that immediately overlie the basement augen-gneisses. Augen-gneiss clasts are present within the Leeukop metaconglomerates. The Damara orogeny has only partly affected the Abbabis rocks of the Tumas River Inlier but further to the west the Husab suite of red granites and granite-gneisses, as field and geochemical evidence suggest, were derived syntectonically during the Damara orogeny by reactivation of the pre- Damara basement. Rõssing alaskitic granites represent late stage melts, that were also derived from Pre- Damara basement rocks during orogenesis, which accumulated post-tectonically in structural traps at the base of the Khomas Subgroup. Salem granitoids are present in synclinal structures associated with metasediments of the Khomas Subgroup and syntectonic derivation by anatexis during the Damara orogeny is suggested. In the east the differentiated Gawib granitoid stock was emplaced post- tectonically through basement rocks into the Damara metasediments. A deep seated origin is indicated by high crystallisation temperatures (>8500°) obtained from quarternary Qz-An-Ab-Or- H₂0 plots. The metamorphic grade increases westwards from medium grade to high grade. In the east, the metapelites contain andalusite, and coexisting muscovite and quartz. This indicates that temperatures of 6000° at 3,5- 4 kb pressure were attained. In the west, coexisting wollastonite and anorthite in the Khan gneisses indicate pressure- temperature conditions of 720° at 4,5-5 kb. Two tectonic events were responsible for the regional structure. An early F₁ episode produced east- west oriented overturned folds and was followed by an intense F₂ episode of isoclinal folding which is responsible for the dominant northeast - southwest regional fabric. The interference of these folds in the proximity of the underlying basement produced the complex dome and basin structures seen in the central and western parts of the area. An F₃ episode of minor importance was also recognized. The presence of continental basement rocks in this central part of the Damara belt is evidence for formation of the orogen by in-situ deformation rather than continental collision.
- Full Text:
- Date Issued: 1978
Secondary effects of oral contraceptives
- Authors: Yuen, E Ho
- Date: 1978
- Subjects: Oral contraceptives , Oral contraceptives -- Side effects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3847 , http://hdl.handle.net/10962/d1012296
- Description: Norethynodrel, a common progestin in oral contraceptives, produces in female rats several significant physiological, cytological and biochemical changes at dose levels of 1 mg and 20 mg per kg: 1) a relative increase in liver mass 2) modification of appearance and extent of the endoplasmic reticulum 3) augmentation of the protein content of the liver 4) increase of the level of cytochrome P- 450 in the liver as determined by : a) difference spectroscopy b) increases in biotransformation of aniline and aminopyrine in vitro and c) reduction of sleeping times of rats dosed with phenobarbital The significance of these findings becomes evident when it is realized that norethynodrel affects and is affected by the same enzyme system which oxidizes medicaments in general in the body: induction of cytochrome P-450 by administration of norethynodrel may interfere with the action of other drugs . Ethinyl estradiol alone showed none of the inductive effects. At high dose levels (20 mg per kg) both norethynodrel and ethinyl estradiol caused a marked inhibition of growth of the animals, producing a net loss of body mass over the 30- day experimental period. Electron micrographic evidence implies that there is also a lowering of glycogen content and a chemical change in the lipids of adrenocortical and liver cells accompanying the use of these agents.
- Full Text:
- Date Issued: 1978
- Authors: Yuen, E Ho
- Date: 1978
- Subjects: Oral contraceptives , Oral contraceptives -- Side effects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3847 , http://hdl.handle.net/10962/d1012296
- Description: Norethynodrel, a common progestin in oral contraceptives, produces in female rats several significant physiological, cytological and biochemical changes at dose levels of 1 mg and 20 mg per kg: 1) a relative increase in liver mass 2) modification of appearance and extent of the endoplasmic reticulum 3) augmentation of the protein content of the liver 4) increase of the level of cytochrome P- 450 in the liver as determined by : a) difference spectroscopy b) increases in biotransformation of aniline and aminopyrine in vitro and c) reduction of sleeping times of rats dosed with phenobarbital The significance of these findings becomes evident when it is realized that norethynodrel affects and is affected by the same enzyme system which oxidizes medicaments in general in the body: induction of cytochrome P-450 by administration of norethynodrel may interfere with the action of other drugs . Ethinyl estradiol alone showed none of the inductive effects. At high dose levels (20 mg per kg) both norethynodrel and ethinyl estradiol caused a marked inhibition of growth of the animals, producing a net loss of body mass over the 30- day experimental period. Electron micrographic evidence implies that there is also a lowering of glycogen content and a chemical change in the lipids of adrenocortical and liver cells accompanying the use of these agents.
- Full Text:
- Date Issued: 1978
Some aspects of the construction and implementation of error-correcting linear codes
- Authors: Booth, Geoffrey L
- Date: 1978
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:20967 , http://hdl.handle.net/10962/5718
- Description: From Conclusion: The study of error-correcting codes is now approximately 25 years old. The first known publication on the subject was in 1949 by M. Golay, who later did much research into the subject of perfect codes. It has been recently established that all the perfect codes are known. R.W. Hamming presented his perfect single-error correcting codes in 1950, in ~n article in the Bell System Technical Journal. These codes turned out to be a special case of the powerful Bose-Chaudhuri codes which were discovered around 1960. Various work has been done on the theory of minimal redundancy of codes for a given error-correcting performance, by Plotkin, Gilbert, Varshamov and others, between 1950 and 1960. The binary BCH codes were found to be so close to the theoretical bounds that, to date, no better codes have been discovered. Although the BCH codes are extremely efficient in terms of ratio of information to check digits, they are not easily, decoded with a minimal amount of apparatus. Petersen in 1961 described an algorithm for d e coding BCH codes, but this was cumbersome compared with the majority-logic methods of Massey and others. Thus the search began for codes which are easily decoded with comparatively simple apparatus. The finite geometry codes which were described by Rudolph in a 1964 thesis were examples of codes which are easily decoded 58 by a small number of steps of majority logic. The simplicial codes of Saltzer are even better in this respect, since they can be decoded by a single step of majority logic, but are rather inefficient . The applications of coding theory have changed over the years, as well. The first computers were huge circuits of relays, which were unreliable and prone to errors. Error correcting codes were required to minimise the possibility of incorrect results. As vacuum tubes and later transistorised circuits made computers more reliable, the need for sophisticated and powerful codes in the computer world diminished. Other used presented themselves however, for example the control systems of unmanned space craft. Because of the difficulty of sending and receiving messages in this case, · very powerful codes were required. Other uses were found in transmission lines and telephone exchanges. The codes considered in this dissertation have, for the most part, been block codes for use on the binary symmetric channel. There are, however, several other applications, such as codes for use on an erasure channel, where bits are corrupted so as to be unrecognizable, rather than changed. There are also codes for burst-error correction, where chennel noise is not randomly distributed, but occurs in "bursts" a few bits long. Certain cyclic codes are of application in these cases. The theory of error correcting codes has risen from virtual non-existence in 1950 to a major and sophisticated part of communication theory. Judging from the articles in journals, it promises to be the subject of a great deal of research for some years to come.
- Full Text:
- Date Issued: 1978
- Authors: Booth, Geoffrey L
- Date: 1978
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:20967 , http://hdl.handle.net/10962/5718
- Description: From Conclusion: The study of error-correcting codes is now approximately 25 years old. The first known publication on the subject was in 1949 by M. Golay, who later did much research into the subject of perfect codes. It has been recently established that all the perfect codes are known. R.W. Hamming presented his perfect single-error correcting codes in 1950, in ~n article in the Bell System Technical Journal. These codes turned out to be a special case of the powerful Bose-Chaudhuri codes which were discovered around 1960. Various work has been done on the theory of minimal redundancy of codes for a given error-correcting performance, by Plotkin, Gilbert, Varshamov and others, between 1950 and 1960. The binary BCH codes were found to be so close to the theoretical bounds that, to date, no better codes have been discovered. Although the BCH codes are extremely efficient in terms of ratio of information to check digits, they are not easily, decoded with a minimal amount of apparatus. Petersen in 1961 described an algorithm for d e coding BCH codes, but this was cumbersome compared with the majority-logic methods of Massey and others. Thus the search began for codes which are easily decoded with comparatively simple apparatus. The finite geometry codes which were described by Rudolph in a 1964 thesis were examples of codes which are easily decoded 58 by a small number of steps of majority logic. The simplicial codes of Saltzer are even better in this respect, since they can be decoded by a single step of majority logic, but are rather inefficient . The applications of coding theory have changed over the years, as well. The first computers were huge circuits of relays, which were unreliable and prone to errors. Error correcting codes were required to minimise the possibility of incorrect results. As vacuum tubes and later transistorised circuits made computers more reliable, the need for sophisticated and powerful codes in the computer world diminished. Other used presented themselves however, for example the control systems of unmanned space craft. Because of the difficulty of sending and receiving messages in this case, · very powerful codes were required. Other uses were found in transmission lines and telephone exchanges. The codes considered in this dissertation have, for the most part, been block codes for use on the binary symmetric channel. There are, however, several other applications, such as codes for use on an erasure channel, where bits are corrupted so as to be unrecognizable, rather than changed. There are also codes for burst-error correction, where chennel noise is not randomly distributed, but occurs in "bursts" a few bits long. Certain cyclic codes are of application in these cases. The theory of error correcting codes has risen from virtual non-existence in 1950 to a major and sophisticated part of communication theory. Judging from the articles in journals, it promises to be the subject of a great deal of research for some years to come.
- Full Text:
- Date Issued: 1978
Studies in ionospheric ray tracing
- Authors: Lambert, Sheridan
- Date: 1978 , 2013-10-21
- Subjects: Ionosphere -- Research -- Graphic methods , Ionospheric radio wave propagation -- Research , Ionograms , Ray tracing algorithms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5501 , http://hdl.handle.net/10962/d1006906 , Ionosphere -- Research -- Graphic methods , Ionospheric radio wave propagation -- Research , Ionograms , Ray tracing algorithms
- Description: The use of ray tracing in the analysis of certain daytime ionograms recorded at Grahamstown is discussed in this thesis. A computer program has been modified and used to trace rays in the frequency range 1 - 30 MHz. Vertical, short distance oblique, and long distance oblique ionograms have been synthesized from the results and compared with experimental ionograms for Grahamstown, the Alice - Grahamstown transmission path (64 km), and the SANAE - Grahamstown transmission path (4470 km) respectively. Ray paths have been calculated and related in detail to the models of the ionosphere and geomagnetic field. The main features of the vertical and short distance oblique ionograms can, in general, be reproduced using spherically stratified ionosphere models with electron density profiles derived from vertical ionograms. A suitable model for the geomagnetic field is a tilted dipole equivalent to the actual field at Grahamstown. The two-hop mode is shown to be, usually, the lowest on the long distance oblique records. The ionosphere model is the principal limiting factor in reproducing such ionograms, and the most satisfactory results have been those obtained with a model in which electron density is assumed to vary linearly with latitude between the profiles at SANAE and Grahamstown. The promising results obtained by ray tracing with normal ionospheric conditions indicate that the method has further possibilities which could usefully be explored. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1978
- Authors: Lambert, Sheridan
- Date: 1978 , 2013-10-21
- Subjects: Ionosphere -- Research -- Graphic methods , Ionospheric radio wave propagation -- Research , Ionograms , Ray tracing algorithms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5501 , http://hdl.handle.net/10962/d1006906 , Ionosphere -- Research -- Graphic methods , Ionospheric radio wave propagation -- Research , Ionograms , Ray tracing algorithms
- Description: The use of ray tracing in the analysis of certain daytime ionograms recorded at Grahamstown is discussed in this thesis. A computer program has been modified and used to trace rays in the frequency range 1 - 30 MHz. Vertical, short distance oblique, and long distance oblique ionograms have been synthesized from the results and compared with experimental ionograms for Grahamstown, the Alice - Grahamstown transmission path (64 km), and the SANAE - Grahamstown transmission path (4470 km) respectively. Ray paths have been calculated and related in detail to the models of the ionosphere and geomagnetic field. The main features of the vertical and short distance oblique ionograms can, in general, be reproduced using spherically stratified ionosphere models with electron density profiles derived from vertical ionograms. A suitable model for the geomagnetic field is a tilted dipole equivalent to the actual field at Grahamstown. The two-hop mode is shown to be, usually, the lowest on the long distance oblique records. The ionosphere model is the principal limiting factor in reproducing such ionograms, and the most satisfactory results have been those obtained with a model in which electron density is assumed to vary linearly with latitude between the profiles at SANAE and Grahamstown. The promising results obtained by ray tracing with normal ionospheric conditions indicate that the method has further possibilities which could usefully be explored. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1978
Studies on the fermentation of molasses by Clostridium acetobutylicum
- Authors: Barber, Jennifer Mary
- Date: 1978
- Subjects: Molasses , Clostridium acetobutylicum , Fermentation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4084 , http://hdl.handle.net/10962/d1007611 , Molasses , Clostridium acetobutylicum , Fermentation
- Description: The bacterium Clostridium acetobutylicum produces acetone and n [subscript] - butanol from molasses in an industrial fermentation system. Although the bacterium has been cultured in liquid media it does not grow well on agar plates and requires high concentrations of hydrogen. Pretreatment of agar plates with bovine catalase improves growth on agar media. The bacteria produce an area of clearing (halo) on Potato agar plates due to butyric acid (the precursor of n [subscript]-butanol) and ß -amylase production. This characteristic will be used as a plate screening assay for the selection of high solvent producing mutants. A laboratory scale fermentation system was developed and detailed studies including pH, turbidity and cell morphology changes, and the details of solvent production were undertaken. The fermentation was optimized for mutant selection. The production of normal solvent yields by isolated clones is required for the mutant selection programme. Studies revealed that sporulation of the clones increased their solvent yield although solvent yields were still lower than normal. Efficient sporulation is therefore a prerequisite for clone fermentation. The origin of the phage infection during the factory outbreak was determined and resistant clones obtained. The presence of a bacteriocin-like toxin causing decreases in turbidity was identified during the final fermentation stage. The strain sensitivity, optimum conditions for stability as well as the kinetics of inactivation and lethality have been investigated. Preliminary characterization and purification studies indicate the proteinaceous nature of the toxin. , KMBT_363
- Full Text:
- Date Issued: 1978
- Authors: Barber, Jennifer Mary
- Date: 1978
- Subjects: Molasses , Clostridium acetobutylicum , Fermentation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4084 , http://hdl.handle.net/10962/d1007611 , Molasses , Clostridium acetobutylicum , Fermentation
- Description: The bacterium Clostridium acetobutylicum produces acetone and n [subscript] - butanol from molasses in an industrial fermentation system. Although the bacterium has been cultured in liquid media it does not grow well on agar plates and requires high concentrations of hydrogen. Pretreatment of agar plates with bovine catalase improves growth on agar media. The bacteria produce an area of clearing (halo) on Potato agar plates due to butyric acid (the precursor of n [subscript]-butanol) and ß -amylase production. This characteristic will be used as a plate screening assay for the selection of high solvent producing mutants. A laboratory scale fermentation system was developed and detailed studies including pH, turbidity and cell morphology changes, and the details of solvent production were undertaken. The fermentation was optimized for mutant selection. The production of normal solvent yields by isolated clones is required for the mutant selection programme. Studies revealed that sporulation of the clones increased their solvent yield although solvent yields were still lower than normal. Efficient sporulation is therefore a prerequisite for clone fermentation. The origin of the phage infection during the factory outbreak was determined and resistant clones obtained. The presence of a bacteriocin-like toxin causing decreases in turbidity was identified during the final fermentation stage. The strain sensitivity, optimum conditions for stability as well as the kinetics of inactivation and lethality have been investigated. Preliminary characterization and purification studies indicate the proteinaceous nature of the toxin. , KMBT_363
- Full Text:
- Date Issued: 1978
Studies on the metabolism of SKF 525 A|
- Authors: Barber, Peter John
- Date: 1978 , 2013-10-14
- Subjects: Drugs -- Metabolism , Cytochrome P-450
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3835 , http://hdl.handle.net/10962/d1007591 , Drugs -- Metabolism , Cytochrome P-450
- Description: Spectrophotometric studies have been carried out to determine the pH dependence of binding of SKF 525 A, Brietal sodium and carbon monoxide to cytochrome P-450. The optimal pH for metabolic conversion of SKF 525 A has been investigated and this agent and its major metabolite, SKF 8742 A, have been metabolised in vitro by swine and rat hepatic microsomes. A suitable gas liquid chromatography assay has been developed and used to analyse metabolic production. The effects of carbon monoxide, dithiothreitol, n-octylamine and of induction of cytochrome P-450 by phenobarbital on metabolism of SKF 525 A and SKF 8742 A have been investigated. Attempts have been made to synthesise SKF 525 AN-oxide. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1978
- Authors: Barber, Peter John
- Date: 1978 , 2013-10-14
- Subjects: Drugs -- Metabolism , Cytochrome P-450
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3835 , http://hdl.handle.net/10962/d1007591 , Drugs -- Metabolism , Cytochrome P-450
- Description: Spectrophotometric studies have been carried out to determine the pH dependence of binding of SKF 525 A, Brietal sodium and carbon monoxide to cytochrome P-450. The optimal pH for metabolic conversion of SKF 525 A has been investigated and this agent and its major metabolite, SKF 8742 A, have been metabolised in vitro by swine and rat hepatic microsomes. A suitable gas liquid chromatography assay has been developed and used to analyse metabolic production. The effects of carbon monoxide, dithiothreitol, n-octylamine and of induction of cytochrome P-450 by phenobarbital on metabolism of SKF 525 A and SKF 8742 A have been investigated. Attempts have been made to synthesise SKF 525 AN-oxide. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1978
The endocoprid dung beetles of southern Africa (Coleoptera: Scarabaeidae)
- Davis, Adrian L V (Adrian Louis Victor)
- Authors: Davis, Adrian L V (Adrian Louis Victor)
- Date: 1978
- Subjects: Dung beetles -- Ecology , Dung beetles -- Africa, Southern
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5845 , http://hdl.handle.net/10962/d1011030 , Dung beetles -- Ecology , Dung beetles -- Africa, Southern
- Description: The biology and ecology of the endocoprid dung beetles of the Aethiopian zoogeographic region has been studied in the field and laboratory. Work has centred mainly on Oniticellus planatus and O. formoaus although infomation has also been supplied on O. egregius, O. pictus and Tragiscus dimidiatus. The taxonomy of Onticellus (s.str.) and Tragiscus has been discussed with the recommendation that O. planattus and O. pseudaplanatus be synonymised. It has been suggested that endocoprid distribution is chiefly controlled by temperature, rainfall and the density of suitable large dung masses. On the basis of distribution it has been suggested that the taxonomic status of the subspecies of O. pictus should be reviewed. Endocoprids (genus Oniticellus (s.str.) are found throughout the warmer regions of Africa and Asia. Tragiscus is found only in Africa. Methods are described for monitoring endocoprids in the field, for distinguishing freshly emerged from older specimens, and for breeding endocoprids under laboratory conditions. It has been shown that endocoprids breed within or just beneath large dung masses unlike most other members of the Scarabaeinae which actively bury dung and construct the their broods at depth in the soil. It has been shown that there is a restriction of breeding sites available to endocoprids due to the removal of dung by the Scarabaeinae beetles and the limited space available within dung pads. This has resulted in low endocoprid population numbers, a disadvantage, which has been countered by highly specialised but opportunistic breeding habits. The requirements of dung plasticity have limited the time available for breeding activity by most endocoprids (excluding O. egresius) so that both the reproductive system and the reproductive behaviour (cf. O. planatus) are geared to rapid egg and brood production. Large numbers of follicles are able to be produced over a short period. In the probable absence of feeding, this has possibly been allowed by the involvement of a well developed fat body. The broods are tended by the parent female during larval development and the follicles are gradually resorbed, probably to prevent starvation. Ovarian recovery is rapid once feeding recommences. Behavioural mechanisms have developed which boost the number of broods constructed and the rapidity with which they are produced. The duration of endocoprid colonisation and the timing of arrival at dung is shown to be related to the rate of pad desiccation which is chiefly controlled by temperature and degree of dung removal by other dung beetles. Precipitation may also play a part. Predation by vertebrates and other insects has been noted and a number of mechanisms are described which are probably protective. Two insect parasitoids of O. formosus larvae have been recorded. The potential use of endocoprids in the Australian dung and fly control project has been discussed and it is recommended that their introduction be considered of low priority. It is suggested that the endocoprids evolved from Euoniticellus type ancestors and that their behaviour complex nidification developed in response to harsh environmental factors, chiefly the danger of desiccation and competition for dung with other dung beetles. From a consideration of brood and brood chamber construction it is suggested that O. egresius is a relatively unspecialised endocoprid which may retain dry season aestivation and has not evolved much further than its probable Euoniticellus type ancestor. The broods are coated in clay and abandoned soon after construction. Greater specialisation is shown by O. planatus and O. formosus which exhibit brooding behaviour, increasing longevity, more specialised brood protection, increased potential fecundity and continuous activity throughout the year. O. formosus shows greater specialisation in brood production than O. planatus. Greatest specialisation is found in T. dimidiatus which exhibits a precise brooding period and low egg production. Brood construction is of a similar degree of specialisation to that of O. formosus. Activity is also continuous throughout the year. The comparative biology of the five southern African endocoprids is summarised in Table 35. Summary, p. 129-131.
- Full Text:
- Date Issued: 1978
- Authors: Davis, Adrian L V (Adrian Louis Victor)
- Date: 1978
- Subjects: Dung beetles -- Ecology , Dung beetles -- Africa, Southern
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5845 , http://hdl.handle.net/10962/d1011030 , Dung beetles -- Ecology , Dung beetles -- Africa, Southern
- Description: The biology and ecology of the endocoprid dung beetles of the Aethiopian zoogeographic region has been studied in the field and laboratory. Work has centred mainly on Oniticellus planatus and O. formoaus although infomation has also been supplied on O. egregius, O. pictus and Tragiscus dimidiatus. The taxonomy of Onticellus (s.str.) and Tragiscus has been discussed with the recommendation that O. planattus and O. pseudaplanatus be synonymised. It has been suggested that endocoprid distribution is chiefly controlled by temperature, rainfall and the density of suitable large dung masses. On the basis of distribution it has been suggested that the taxonomic status of the subspecies of O. pictus should be reviewed. Endocoprids (genus Oniticellus (s.str.) are found throughout the warmer regions of Africa and Asia. Tragiscus is found only in Africa. Methods are described for monitoring endocoprids in the field, for distinguishing freshly emerged from older specimens, and for breeding endocoprids under laboratory conditions. It has been shown that endocoprids breed within or just beneath large dung masses unlike most other members of the Scarabaeinae which actively bury dung and construct the their broods at depth in the soil. It has been shown that there is a restriction of breeding sites available to endocoprids due to the removal of dung by the Scarabaeinae beetles and the limited space available within dung pads. This has resulted in low endocoprid population numbers, a disadvantage, which has been countered by highly specialised but opportunistic breeding habits. The requirements of dung plasticity have limited the time available for breeding activity by most endocoprids (excluding O. egresius) so that both the reproductive system and the reproductive behaviour (cf. O. planatus) are geared to rapid egg and brood production. Large numbers of follicles are able to be produced over a short period. In the probable absence of feeding, this has possibly been allowed by the involvement of a well developed fat body. The broods are tended by the parent female during larval development and the follicles are gradually resorbed, probably to prevent starvation. Ovarian recovery is rapid once feeding recommences. Behavioural mechanisms have developed which boost the number of broods constructed and the rapidity with which they are produced. The duration of endocoprid colonisation and the timing of arrival at dung is shown to be related to the rate of pad desiccation which is chiefly controlled by temperature and degree of dung removal by other dung beetles. Precipitation may also play a part. Predation by vertebrates and other insects has been noted and a number of mechanisms are described which are probably protective. Two insect parasitoids of O. formosus larvae have been recorded. The potential use of endocoprids in the Australian dung and fly control project has been discussed and it is recommended that their introduction be considered of low priority. It is suggested that the endocoprids evolved from Euoniticellus type ancestors and that their behaviour complex nidification developed in response to harsh environmental factors, chiefly the danger of desiccation and competition for dung with other dung beetles. From a consideration of brood and brood chamber construction it is suggested that O. egresius is a relatively unspecialised endocoprid which may retain dry season aestivation and has not evolved much further than its probable Euoniticellus type ancestor. The broods are coated in clay and abandoned soon after construction. Greater specialisation is shown by O. planatus and O. formosus which exhibit brooding behaviour, increasing longevity, more specialised brood protection, increased potential fecundity and continuous activity throughout the year. O. formosus shows greater specialisation in brood production than O. planatus. Greatest specialisation is found in T. dimidiatus which exhibits a precise brooding period and low egg production. Brood construction is of a similar degree of specialisation to that of O. formosus. Activity is also continuous throughout the year. The comparative biology of the five southern African endocoprids is summarised in Table 35. Summary, p. 129-131.
- Full Text:
- Date Issued: 1978
The geochemistry and petrology of Karroo basalts of the Barkly East area, north eastern Cape
- Authors: Pemberton, John
- Date: 1978 , 2013-10-17
- Subjects: Basalt -- South Africa -- Eastern Cape , Petrology -- South Africa -- Eastern Cape , Geochemistry -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5042 , http://hdl.handle.net/10962/d1007646 , Basalt -- South Africa -- Eastern Cape , Petrology -- South Africa -- Eastern Cape , Geochemistry -- South Africa -- Eastern Cape
- Description: Sixty one basalt samples from the Drakensberg Subgroup in the Barkly East area were analysed for major elements and fourteen trace elements viz. Sr, Rb, Zr, Y, Nb, Zn, Cu, Ni, Co, V, Cr, La, Ce and Nd . These data confirm the tholeiitic nature of the Drakensberg Subgroup. Geochemical differences in the major element compositions are small within the different units of the Drakensberg Subgroup. Small differences are also evident between these units. The trace element variation between the units and within the Lesotho Formation are more pronounced than the variation of the major elements. The Lesotho Formation samples show a minor vertical increase in value for the top half of the Naudes Nek section in Fe, Ti, P, Zr, Nb, Y, La, Ce and Nd . A decrease in value from the same position in Mg, Ni and Co was observed. These patterns of variation are interpreted as representing low-pressure fractionation of plagioclase, olivine and clinopyroxene. Differences between the units of the Drakensberg Subgroup are examined by using absolute trace element contents and interelement ratios. Ratios of incompatible elements differ for the different units leading to the suggestion that a heterogeneous mantle is the most likely explanation for these differences. A unique unit of flows designated the Omega Formation is examined. The basal massive unit displays an unusual pattern of variation with height which suggests an origin through two different differentiation mechanisms. The data from this thesis are compared with those of Cox and Hornung (1966) on the central Lesotho basalts, Bristow (1976) on the southern Lebombo basalts and Robey (1976) on the Karroo dolerites of the Eastern Cape. The geochemical comparison between the lavas of the Lesotho Formation in the Barkly East area, central Lesotho and the Karroo dolerites show no major differences. However the southern Lebombo basalts show an enrichment in Sr and depletion in Cr.
- Full Text:
- Date Issued: 1978
- Authors: Pemberton, John
- Date: 1978 , 2013-10-17
- Subjects: Basalt -- South Africa -- Eastern Cape , Petrology -- South Africa -- Eastern Cape , Geochemistry -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5042 , http://hdl.handle.net/10962/d1007646 , Basalt -- South Africa -- Eastern Cape , Petrology -- South Africa -- Eastern Cape , Geochemistry -- South Africa -- Eastern Cape
- Description: Sixty one basalt samples from the Drakensberg Subgroup in the Barkly East area were analysed for major elements and fourteen trace elements viz. Sr, Rb, Zr, Y, Nb, Zn, Cu, Ni, Co, V, Cr, La, Ce and Nd . These data confirm the tholeiitic nature of the Drakensberg Subgroup. Geochemical differences in the major element compositions are small within the different units of the Drakensberg Subgroup. Small differences are also evident between these units. The trace element variation between the units and within the Lesotho Formation are more pronounced than the variation of the major elements. The Lesotho Formation samples show a minor vertical increase in value for the top half of the Naudes Nek section in Fe, Ti, P, Zr, Nb, Y, La, Ce and Nd . A decrease in value from the same position in Mg, Ni and Co was observed. These patterns of variation are interpreted as representing low-pressure fractionation of plagioclase, olivine and clinopyroxene. Differences between the units of the Drakensberg Subgroup are examined by using absolute trace element contents and interelement ratios. Ratios of incompatible elements differ for the different units leading to the suggestion that a heterogeneous mantle is the most likely explanation for these differences. A unique unit of flows designated the Omega Formation is examined. The basal massive unit displays an unusual pattern of variation with height which suggests an origin through two different differentiation mechanisms. The data from this thesis are compared with those of Cox and Hornung (1966) on the central Lesotho basalts, Bristow (1976) on the southern Lebombo basalts and Robey (1976) on the Karroo dolerites of the Eastern Cape. The geochemical comparison between the lavas of the Lesotho Formation in the Barkly East area, central Lesotho and the Karroo dolerites show no major differences. However the southern Lebombo basalts show an enrichment in Sr and depletion in Cr.
- Full Text:
- Date Issued: 1978
The in vivo and quantitative assessment of topical corticosteroid formulations
- Authors: Coleman, Gerald Leslie
- Date: 1978 , 2013-10-14
- Subjects: Dermatopharmacology , Dermatologic agents , Skin absorption , Adrenocortical hormones -- Therapeutic use , Transdermal medication -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3857 , http://hdl.handle.net/10962/d1013337
- Full Text:
- Date Issued: 1978
- Authors: Coleman, Gerald Leslie
- Date: 1978 , 2013-10-14
- Subjects: Dermatopharmacology , Dermatologic agents , Skin absorption , Adrenocortical hormones -- Therapeutic use , Transdermal medication -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3857 , http://hdl.handle.net/10962/d1013337
- Full Text:
- Date Issued: 1978
The study of the metabolism of phenylbutazone (4-butyl-1,2 -diphenylpyrazolidine - 3,5 - dione) in rats
- Authors: Alexander, Dorothy Mary
- Date: 1978 , 2013-10-18
- Subjects: Drugs -- Metabolism , Phenylbutazone
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3832 , http://hdl.handle.net/10962/d1007468 , Drugs -- Metabolism , Phenylbutazone
- Description: In this study the metabolism of the anti-arthritic drug, phenylbutazone, was investigated in female Wistar rats, and the results compared with those of other workers in this field. Two interrelated projects were undertaken. The first covered the pattern of excretion, isolation and characterisation of the metabolites and decomposition products of phenylbutazone in rats dosed post-orally with the drug. It was found that the major route of excretion was via the urine and over 50% of the administered dose was excreted in the first 24 hours by this route. A small percentage of the dose was excreted in the faeces. The following compounds were identified using chromatographic and autoradiographic techniques: p-Hydroxy derivative of phenylbutazone γ-Hydroxy derivative of phenylbutazone in both its molecular forms (ring lactone and straight chain hydroxyl) 4-Hydroxy derivative of phenylbutazone p-γ-Dihydroxy derivative of phenylbutazone p-4-Dihydroxy derivative of phenylbutazone Hydrolysable conjugates (possibly glucuronides) Water soluble non-hydrolysable conjugates. The second project dealt with the quantitation of the water insoluble compounds isolated in the initial work. Using a unique technique, combining inverse isotope dilution assay and spectrophotometric analysis, it was found that the major metabolite was the γ-hydroxy derivative of phenylbutazone, present in both its molecular forms. Oxyphenbutazone was a minor metabolite and the p-γ-dihydroxy derivative of phenylbutazone was present only in very low concentration. These results did not conform with those of previous workers in this field who reported the γ-hydroxy derivative of phenylbutazone, in one molecular form only, as the major metabolite and the dihydroxy derivative as the second metabolite with a higher concentration in the urine than oxyphenbutazone. This disparity could be due to the fact that these workers took no account of the presence of the two molecular forms of the γ-hydroxy derivative of phenylbutazone with their different polarities and different Rf values. The present study showed that the straight chain hydroxyl isomer was probably mistakenly identified as the p-γ-dihydroxy derivative of phenylbutazone. This theory is supported by the fact that the percentage dose recovered by the previous workers of the γ-hydroxy and p-γ-dihydroxy derivatives together equalled the percentage dose recovered in this study of the two molecular forms of the γ-hydroxy derivative. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1978
- Authors: Alexander, Dorothy Mary
- Date: 1978 , 2013-10-18
- Subjects: Drugs -- Metabolism , Phenylbutazone
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3832 , http://hdl.handle.net/10962/d1007468 , Drugs -- Metabolism , Phenylbutazone
- Description: In this study the metabolism of the anti-arthritic drug, phenylbutazone, was investigated in female Wistar rats, and the results compared with those of other workers in this field. Two interrelated projects were undertaken. The first covered the pattern of excretion, isolation and characterisation of the metabolites and decomposition products of phenylbutazone in rats dosed post-orally with the drug. It was found that the major route of excretion was via the urine and over 50% of the administered dose was excreted in the first 24 hours by this route. A small percentage of the dose was excreted in the faeces. The following compounds were identified using chromatographic and autoradiographic techniques: p-Hydroxy derivative of phenylbutazone γ-Hydroxy derivative of phenylbutazone in both its molecular forms (ring lactone and straight chain hydroxyl) 4-Hydroxy derivative of phenylbutazone p-γ-Dihydroxy derivative of phenylbutazone p-4-Dihydroxy derivative of phenylbutazone Hydrolysable conjugates (possibly glucuronides) Water soluble non-hydrolysable conjugates. The second project dealt with the quantitation of the water insoluble compounds isolated in the initial work. Using a unique technique, combining inverse isotope dilution assay and spectrophotometric analysis, it was found that the major metabolite was the γ-hydroxy derivative of phenylbutazone, present in both its molecular forms. Oxyphenbutazone was a minor metabolite and the p-γ-dihydroxy derivative of phenylbutazone was present only in very low concentration. These results did not conform with those of previous workers in this field who reported the γ-hydroxy derivative of phenylbutazone, in one molecular form only, as the major metabolite and the dihydroxy derivative as the second metabolite with a higher concentration in the urine than oxyphenbutazone. This disparity could be due to the fact that these workers took no account of the presence of the two molecular forms of the γ-hydroxy derivative of phenylbutazone with their different polarities and different Rf values. The present study showed that the straight chain hydroxyl isomer was probably mistakenly identified as the p-γ-dihydroxy derivative of phenylbutazone. This theory is supported by the fact that the percentage dose recovered by the previous workers of the γ-hydroxy and p-γ-dihydroxy derivatives together equalled the percentage dose recovered in this study of the two molecular forms of the γ-hydroxy derivative. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
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- Date Issued: 1978
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