An investigation of the structure of the Southern Hemisphere radio-meteor streams
- Authors: Roux, David Gerhardus
- Date: 1988
- Subjects: Radio meteorology -- Southern Hemisphere , Solar system
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5448 , http://hdl.handle.net/10962/d1004587 , Radio meteorology -- Southern Hemisphere , Solar system
- Description: Our current knowledge of the Solar System, with a particular emphasis on the systems of interplanetary objects, is reviewed, and the theory of meteors and the reflection of radio waves from meteoric ionization is then discussed. A description of the meteor radar is given and a method of calibrating the antenna beam is developed. The main project comprises two parts: (a) A general survey of the radar echorate for 20 major and minor meteor streams and the sporadic meteor background, conducted from Grahamstown over the period 1986 April to 1988 January, is described. Definite shower activity was observed for all of the major and some of the minor showers. (b) Based on a scheme proposed by previous workers (Morton & Jones), a method of recovering meteor radiant distributions from the distribution of echo directions is developed. We devise a technique of compensating for possible distortions of the resulting radiant maps, which may arise due to the arisotropic antenna beam. This involves a system of echo-weighting. Radiant maps which showed considerably less distortion than those of the above workers were obtained without the weighting procedure. It is concluded that, although the method in its present form introduces spurious features into the maps, the principle is sound and should eventually be refined to produce the desired compensation
- Full Text:
- Authors: Roux, David Gerhardus
- Date: 1988
- Subjects: Radio meteorology -- Southern Hemisphere , Solar system
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5448 , http://hdl.handle.net/10962/d1004587 , Radio meteorology -- Southern Hemisphere , Solar system
- Description: Our current knowledge of the Solar System, with a particular emphasis on the systems of interplanetary objects, is reviewed, and the theory of meteors and the reflection of radio waves from meteoric ionization is then discussed. A description of the meteor radar is given and a method of calibrating the antenna beam is developed. The main project comprises two parts: (a) A general survey of the radar echorate for 20 major and minor meteor streams and the sporadic meteor background, conducted from Grahamstown over the period 1986 April to 1988 January, is described. Definite shower activity was observed for all of the major and some of the minor showers. (b) Based on a scheme proposed by previous workers (Morton & Jones), a method of recovering meteor radiant distributions from the distribution of echo directions is developed. We devise a technique of compensating for possible distortions of the resulting radiant maps, which may arise due to the arisotropic antenna beam. This involves a system of echo-weighting. Radiant maps which showed considerably less distortion than those of the above workers were obtained without the weighting procedure. It is concluded that, although the method in its present form introduces spurious features into the maps, the principle is sound and should eventually be refined to produce the desired compensation
- Full Text:
Application of high-performance liquid chromatography for the analysis and pharmocokinetics of mephenoxalone
- Authors: Van der Westhuizen, Fiona
- Date: 1988 , 2013-03-06
- Subjects: High performance liquid chromatography , Central nervous system depressants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3810 , http://hdl.handle.net/10962/d1004385 , High performance liquid chromatography , Central nervous system depressants
- Description: Mephenoxalone is a mild central nervous system depressant with activity resembling that of meprobamate. Since its introduction in 1961 mephenoxalone has been used as an anxiolytic and as a muscle relaxant, although the latter effect is weak. Preliminary studies on the absorption and disposition of mephenoxalone have been conducted in beagle dogs but no pharmacokinetic data from human studies have been reported, except for a single study in which the biotransformation products present in human urine were identified. Methods presently available for the determination of mephenoxalone in biological fluids lack the sensitivity, specificity and precision required for detailed pharmacokinetic studies. In this study, a rapid, sensitive, precise reverse-phase high-performance liquid chromatographic method with ultraviolet detection at 200nm was employed for the determination of mephenoxalone in biological fluids. Serum and urine samples were prepared for chromatographic analysis using simple liquid-liquid extraction techniques. The application of the assay to pharmacokinetic studies in humans is presented. After administration of a single oral dose of 400mg mephenoxalone dispersed in 150ml water to six young, healthy volunteers, the compound was rapidly absorbed with the peak concentration of 8μg/ml occurring after about 1 hour. The elimination half-life was approximately 3 hours. The drug was extensively metabolized with only about 1 percent of the administered dose being excreted unchanged in the urine after 24 hours. The bioavailability of a newly developed mephenoxalone-containing tablet was also investigated. The drug was absorbed more rapidly from the tablet than from the dispersed dose. This was attributed to a shorter in vivo dissolution time on the basis of in vitro tests, but this effect is not expected to be clinically significant. In addition, two human urinary metabolites of mephenoxalone were identified as unconjugated hydroxylated derivatives using thermospray HPLC-mass spectrometry. The plasma protein-binding properties of mephenoxalone were also investigated.
- Full Text:
- Authors: Van der Westhuizen, Fiona
- Date: 1988 , 2013-03-06
- Subjects: High performance liquid chromatography , Central nervous system depressants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3810 , http://hdl.handle.net/10962/d1004385 , High performance liquid chromatography , Central nervous system depressants
- Description: Mephenoxalone is a mild central nervous system depressant with activity resembling that of meprobamate. Since its introduction in 1961 mephenoxalone has been used as an anxiolytic and as a muscle relaxant, although the latter effect is weak. Preliminary studies on the absorption and disposition of mephenoxalone have been conducted in beagle dogs but no pharmacokinetic data from human studies have been reported, except for a single study in which the biotransformation products present in human urine were identified. Methods presently available for the determination of mephenoxalone in biological fluids lack the sensitivity, specificity and precision required for detailed pharmacokinetic studies. In this study, a rapid, sensitive, precise reverse-phase high-performance liquid chromatographic method with ultraviolet detection at 200nm was employed for the determination of mephenoxalone in biological fluids. Serum and urine samples were prepared for chromatographic analysis using simple liquid-liquid extraction techniques. The application of the assay to pharmacokinetic studies in humans is presented. After administration of a single oral dose of 400mg mephenoxalone dispersed in 150ml water to six young, healthy volunteers, the compound was rapidly absorbed with the peak concentration of 8μg/ml occurring after about 1 hour. The elimination half-life was approximately 3 hours. The drug was extensively metabolized with only about 1 percent of the administered dose being excreted unchanged in the urine after 24 hours. The bioavailability of a newly developed mephenoxalone-containing tablet was also investigated. The drug was absorbed more rapidly from the tablet than from the dispersed dose. This was attributed to a shorter in vivo dissolution time on the basis of in vitro tests, but this effect is not expected to be clinically significant. In addition, two human urinary metabolites of mephenoxalone were identified as unconjugated hydroxylated derivatives using thermospray HPLC-mass spectrometry. The plasma protein-binding properties of mephenoxalone were also investigated.
- Full Text:
Application of high-performance liquid chromatography to the analysis, stability and pharmacokinetics of erythromycin
- Authors: Stubbs, Christopher
- Date: 1988
- Subjects: Erythromycin High performance liquid chromatography
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3809 , http://hdl.handle.net/10962/d1004372
- Description: Erythromycin is a macrolide antibiotic used mainly in the treatment of infections caused by gram-positive organisms. Erythromycin base is rap idly degraded in acidic media necessitating the use of structurally modified erythromycin derivatives or acid resistant dosage forms in order to decrease gastric inactivation of the drug. The majority of pharmacokinetic studies to-date have utilized relatively non-specific microbiological assay procedures which are unable to differentiate between concentrations of active erythromycin base and the inactive pro-drug derivatives. A high-performance liquid chromatographic (HPLC) technique is described for the simultaneous determination of erythromycin base and propionate (inactive pro-drug form) in human serum and urine following the oral administration of erythromycin estolate, an acid stable derivative of erythromycin. The method involves a solid-phase extraction step prior to chromatography on a C18 reversed-phase column with coulometric electrochemical detection. Sample handling and storage techniques are presented which minimize hydrolysis of the inactive ester moiety between sample collection and analysis, thereby more accurately reflecting the in vivo situation than in previously published studies. Results from single dose pharmacokinetic studies indicate that only 10-15% of the total erythromycin concentration in vivo is present as the active base component following oral administration of erythromycin estolate. This percentage increases to approximately 25% during multiple dose administration. Novel urinary excretion data are presented which reveal that approximately 40% and 55% of the total erythromycin excreted in urine is excreted as erythromycin base following single and multiple dosages respectively. Computer fitting of mean serum concentration-time data revealed that an open one compartment model with linear first order absorption and elimination best described the absorption and disposition of erythromycin, although poor computer fits for individual data sets were observed. Some evidence of non-linear elimination is presented utilizing both compartmental and non-compartmental pharmacokinetic techniques. Large intra-and inter-personal variability in erythromycin absorption and disposition was experienced which was evaluated in five subjects who each received one 500 mg erythromycin estolate tablet from the same batch, on three separate occasions. In addition. an HPLC method is described for the analysis of "total erythromycin" concentrations following erythromycin estolate administration which involves hydrolysis of the ester component prior to chromatography. as well as an HPLC method utilizing amperometric electrochemical detection capable of monitoring the stability of erythromycin base in stored biological fluids. These methods were uti I ized in various stability studies involving erythromycin base and propionate as well as for the analysis of erythromycin estolate dosage forms.
- Full Text:
- Authors: Stubbs, Christopher
- Date: 1988
- Subjects: Erythromycin High performance liquid chromatography
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3809 , http://hdl.handle.net/10962/d1004372
- Description: Erythromycin is a macrolide antibiotic used mainly in the treatment of infections caused by gram-positive organisms. Erythromycin base is rap idly degraded in acidic media necessitating the use of structurally modified erythromycin derivatives or acid resistant dosage forms in order to decrease gastric inactivation of the drug. The majority of pharmacokinetic studies to-date have utilized relatively non-specific microbiological assay procedures which are unable to differentiate between concentrations of active erythromycin base and the inactive pro-drug derivatives. A high-performance liquid chromatographic (HPLC) technique is described for the simultaneous determination of erythromycin base and propionate (inactive pro-drug form) in human serum and urine following the oral administration of erythromycin estolate, an acid stable derivative of erythromycin. The method involves a solid-phase extraction step prior to chromatography on a C18 reversed-phase column with coulometric electrochemical detection. Sample handling and storage techniques are presented which minimize hydrolysis of the inactive ester moiety between sample collection and analysis, thereby more accurately reflecting the in vivo situation than in previously published studies. Results from single dose pharmacokinetic studies indicate that only 10-15% of the total erythromycin concentration in vivo is present as the active base component following oral administration of erythromycin estolate. This percentage increases to approximately 25% during multiple dose administration. Novel urinary excretion data are presented which reveal that approximately 40% and 55% of the total erythromycin excreted in urine is excreted as erythromycin base following single and multiple dosages respectively. Computer fitting of mean serum concentration-time data revealed that an open one compartment model with linear first order absorption and elimination best described the absorption and disposition of erythromycin, although poor computer fits for individual data sets were observed. Some evidence of non-linear elimination is presented utilizing both compartmental and non-compartmental pharmacokinetic techniques. Large intra-and inter-personal variability in erythromycin absorption and disposition was experienced which was evaluated in five subjects who each received one 500 mg erythromycin estolate tablet from the same batch, on three separate occasions. In addition. an HPLC method is described for the analysis of "total erythromycin" concentrations following erythromycin estolate administration which involves hydrolysis of the ester component prior to chromatography. as well as an HPLC method utilizing amperometric electrochemical detection capable of monitoring the stability of erythromycin base in stored biological fluids. These methods were uti I ized in various stability studies involving erythromycin base and propionate as well as for the analysis of erythromycin estolate dosage forms.
- Full Text:
Art as an expression of the unconscious psyche
- Authors: Weiner, Elana
- Date: 1988
- Subjects: Art -- Psychology , Art and mental illness , Art therapy , Subconsciousness
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3119 , http://hdl.handle.net/10962/d1004903 , Art -- Psychology , Art and mental illness , Art therapy , Subconsciousness
- Description: This study aimed to investigate the use of expressive art as a manifestation of the unconscious psyche and as an indication of underlying personality dynamics. Its use as a significant medium for therapeutic encounter and exploration was investigated by analysing the art produced by four psychiatric in-patients during their participation in an eight-week art therapy programme. Each patient's art series was qualitatively and thematically interpreted with a focus upon the meaning of significant recurring images and motifs. The results of this study indicate that the particularity of each patient's graphic imagery enabled the lived experience of their struggles and preoccupations to emerge as uniquely different. Through their art productions they revealed the nature of their inner worlds and the power of their thoughts, feelings and experiences.
- Full Text:
- Authors: Weiner, Elana
- Date: 1988
- Subjects: Art -- Psychology , Art and mental illness , Art therapy , Subconsciousness
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3119 , http://hdl.handle.net/10962/d1004903 , Art -- Psychology , Art and mental illness , Art therapy , Subconsciousness
- Description: This study aimed to investigate the use of expressive art as a manifestation of the unconscious psyche and as an indication of underlying personality dynamics. Its use as a significant medium for therapeutic encounter and exploration was investigated by analysing the art produced by four psychiatric in-patients during their participation in an eight-week art therapy programme. Each patient's art series was qualitatively and thematically interpreted with a focus upon the meaning of significant recurring images and motifs. The results of this study indicate that the particularity of each patient's graphic imagery enabled the lived experience of their struggles and preoccupations to emerge as uniquely different. Through their art productions they revealed the nature of their inner worlds and the power of their thoughts, feelings and experiences.
- Full Text:
Aspects of the biology and population dynamics of the geelbek Atractoscion aequidens (Cuvier) (Pisces: Sciaenidae) off the South African coast
- Authors: Griffiths, Marc H
- Date: 1988
- Subjects: Sciaenidae -- South Africa Fish populations -- South Africa Atractoscion Atractoscion -- South Africa -- Ecology Atractoscion -- South Africa -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5194 , http://hdl.handle.net/10962/d1001970
- Description: The geelbek Atractoscion aeguidens is an important commercial and recreational linefish species along the South African eastern seaboard . Aspects of its biology and population dynamics were investigated using data collected from various sampling sites along the South African east coast and from catch statistics obtained from both the Sea Fisheries Research Institute (Cape Town), and dealer records. The biological aspects studied included age and growth, reproduction and feeding. It was established that A. aeguidens is a fast growing species with a relatively late age at sexual maturity and a 1:1 sex ratio. Feeding studies revealed that it has become specialized to feed on small pelagic fish. The South African geelbek stock consists of three distinct age related sub-populations, each representing a particular phase in the life cycle. The sub-adults (1-4 yrs) occur in the South West Cape and feed predominantly on anchovy, Engraulis capensis, which they follow, moving inshore in summer and offshore in winter. The adults (5-9 yrs) undergo a seasonal inshore migration to Natal where they spawn in spring. The dynamics of this migration are strongly influenced by the annual movement of their principal prey viz. , Sardinops ocellatus, to that region. As a result the geelbek first arrive in Natal during mid winter. Evidence is also presented to suggest that a significant number of "adolescent " fish (4-5 yrs) undergo limited gonad maturation and a partial migration to at least as far as the South East Cape. Spawning appears to occur offshore. It is postulated that eggs and larvae are transported southwards by the peripheral waters of the Agulhas Current. After spawning the adults probably remain offshore and use the current to aid their return to the South and South West Cape, where they spend summer feeding on the Agulhas Bank. Juveniles (<1 yr) first appear in the South East Cape between January and March. They apparently use this region as a nursery area for almost a year before moving southwards to join the sub-adults in the South West Cape. In the South East Cape, the juveniles feed initially on mysids whereafter they switch to anchovies and pilchards. A preliminary stock assessment using yield per recruit and spawner biomass per recruit models, indicated that despite the current legislation the South African geelbek population is already overexploited. This is largely attributed to high rates of fishing mortality of the migratory adult population. Further management recommendations are therefore proposed. These include a size limit (660 mm FL), derived from an investigation of the interrelationship between natural mortality and somatic growth in a theoretical unexploited cohort, as well as a uniform bag limit for all user groups (5 fish per person per day)
- Full Text:
- Authors: Griffiths, Marc H
- Date: 1988
- Subjects: Sciaenidae -- South Africa Fish populations -- South Africa Atractoscion Atractoscion -- South Africa -- Ecology Atractoscion -- South Africa -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5194 , http://hdl.handle.net/10962/d1001970
- Description: The geelbek Atractoscion aeguidens is an important commercial and recreational linefish species along the South African eastern seaboard . Aspects of its biology and population dynamics were investigated using data collected from various sampling sites along the South African east coast and from catch statistics obtained from both the Sea Fisheries Research Institute (Cape Town), and dealer records. The biological aspects studied included age and growth, reproduction and feeding. It was established that A. aeguidens is a fast growing species with a relatively late age at sexual maturity and a 1:1 sex ratio. Feeding studies revealed that it has become specialized to feed on small pelagic fish. The South African geelbek stock consists of three distinct age related sub-populations, each representing a particular phase in the life cycle. The sub-adults (1-4 yrs) occur in the South West Cape and feed predominantly on anchovy, Engraulis capensis, which they follow, moving inshore in summer and offshore in winter. The adults (5-9 yrs) undergo a seasonal inshore migration to Natal where they spawn in spring. The dynamics of this migration are strongly influenced by the annual movement of their principal prey viz. , Sardinops ocellatus, to that region. As a result the geelbek first arrive in Natal during mid winter. Evidence is also presented to suggest that a significant number of "adolescent " fish (4-5 yrs) undergo limited gonad maturation and a partial migration to at least as far as the South East Cape. Spawning appears to occur offshore. It is postulated that eggs and larvae are transported southwards by the peripheral waters of the Agulhas Current. After spawning the adults probably remain offshore and use the current to aid their return to the South and South West Cape, where they spend summer feeding on the Agulhas Bank. Juveniles (<1 yr) first appear in the South East Cape between January and March. They apparently use this region as a nursery area for almost a year before moving southwards to join the sub-adults in the South West Cape. In the South East Cape, the juveniles feed initially on mysids whereafter they switch to anchovies and pilchards. A preliminary stock assessment using yield per recruit and spawner biomass per recruit models, indicated that despite the current legislation the South African geelbek population is already overexploited. This is largely attributed to high rates of fishing mortality of the migratory adult population. Further management recommendations are therefore proposed. These include a size limit (660 mm FL), derived from an investigation of the interrelationship between natural mortality and somatic growth in a theoretical unexploited cohort, as well as a uniform bag limit for all user groups (5 fish per person per day)
- Full Text:
Aspects of the biology of the musselcracker, Sparodon Durbanensis, and the bronze bream, Pachymetopon grande, (Pisces : Sparidae), with notes on the Eastern Cape recreational rock-angling and spear fisheries
- Authors: Clarke, John Ross
- Date: 1988
- Subjects: Sparidea -- South Africa Sparodon Durbanensis Bream fishing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5190 , http://hdl.handle.net/10962/d1001966
- Description: The musselcracker, Soarodon durbanensis, and the bronze bream, Pachymetopon arande, are important components of rock-angling and spearfishing catches In the Eastern Cape. Aspects of their biology, including age and growth, reproduction, nursery areas and feeding, were Investigated to provide a basis for the rational exploitation of the resource. Both species are slow-growing and long-lived. Growth in S. durbanensls was described by the von Bertalanffy growth equation: Lt(mm) = 1021.2(1-e⁻°.°⁹°°⁽t ⁻° .⁷°⁹⁾). The von Bertalanffy growth model did not describe the total data set in P. grande, but by excluding the zero and one year old fish the data were described by: Lt(mm) = 461.1(1-e⁻°.¹⁵³⁽t ⁺¹.⁶⁴°⁾). Detailed histological examination of gonadal development showed that S. durbanensis and P. grande are rudimentary hermaphrodites. Both species had restricted breeding seasons which coincided with peak exploitation. Results indicated that both species are group spawners with pelagic eggs. Size at 50% maturity in S. durbanensis and P. grande was determined at 350 and 300mm fork length, respectively, corresponding to ages of 4.5 and 5.5 years. Intertidal pools functioned as nursery areas for S. durbanensis during the first year, whereas subtidal waters were more important for larger juveniles. P. grande juveniles were commonly observed on subtidal weed beds to a depth of 10m. A size-related change in the diet of S. durbanensis was observed. The juveniles were omnivorous, feeding predominantly on gastropods, echinoids and chlorophytes. The adults fed on a variety of large, reef-associated invertebrates. P. grande were omnivorous, with macroalgae being the principal dietary component. This species appears to utilise the storage and extracellular carbohydrates of the macroalgae. Results showed that macroalgal degradation by gut endosymbionts and the utilisation of macroalgal epibionts does not appear to occur in this species. A detailed analysis of catch composition and catch per unit of effort In the Port Elizabeth rock-angling fishery and the Eastern Cape spearfishery emphasised the recreational importance of S. durbanensis and P. grande. The localised distribution, slow growth and late maturation in both species results in their being susceptible to over-exploitation in these size-selective fisheries. Current legislation protecting these fish is discussed in relation to the findings of this study and additional management measures are proposed.
- Full Text:
- Authors: Clarke, John Ross
- Date: 1988
- Subjects: Sparidea -- South Africa Sparodon Durbanensis Bream fishing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5190 , http://hdl.handle.net/10962/d1001966
- Description: The musselcracker, Soarodon durbanensis, and the bronze bream, Pachymetopon arande, are important components of rock-angling and spearfishing catches In the Eastern Cape. Aspects of their biology, including age and growth, reproduction, nursery areas and feeding, were Investigated to provide a basis for the rational exploitation of the resource. Both species are slow-growing and long-lived. Growth in S. durbanensls was described by the von Bertalanffy growth equation: Lt(mm) = 1021.2(1-e⁻°.°⁹°°⁽t ⁻° .⁷°⁹⁾). The von Bertalanffy growth model did not describe the total data set in P. grande, but by excluding the zero and one year old fish the data were described by: Lt(mm) = 461.1(1-e⁻°.¹⁵³⁽t ⁺¹.⁶⁴°⁾). Detailed histological examination of gonadal development showed that S. durbanensis and P. grande are rudimentary hermaphrodites. Both species had restricted breeding seasons which coincided with peak exploitation. Results indicated that both species are group spawners with pelagic eggs. Size at 50% maturity in S. durbanensis and P. grande was determined at 350 and 300mm fork length, respectively, corresponding to ages of 4.5 and 5.5 years. Intertidal pools functioned as nursery areas for S. durbanensis during the first year, whereas subtidal waters were more important for larger juveniles. P. grande juveniles were commonly observed on subtidal weed beds to a depth of 10m. A size-related change in the diet of S. durbanensis was observed. The juveniles were omnivorous, feeding predominantly on gastropods, echinoids and chlorophytes. The adults fed on a variety of large, reef-associated invertebrates. P. grande were omnivorous, with macroalgae being the principal dietary component. This species appears to utilise the storage and extracellular carbohydrates of the macroalgae. Results showed that macroalgal degradation by gut endosymbionts and the utilisation of macroalgal epibionts does not appear to occur in this species. A detailed analysis of catch composition and catch per unit of effort In the Port Elizabeth rock-angling fishery and the Eastern Cape spearfishery emphasised the recreational importance of S. durbanensis and P. grande. The localised distribution, slow growth and late maturation in both species results in their being susceptible to over-exploitation in these size-selective fisheries. Current legislation protecting these fish is discussed in relation to the findings of this study and additional management measures are proposed.
- Full Text:
Aspects of the transdermal permeation and analysis of betamethasone 17-valerate
- Authors: Smith, Eric W
- Date: 1988
- Subjects: Transdermal medication Skin absorption Dermatologic agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3815 , http://hdl.handle.net/10962/d1004741
- Description: The current world-wide interest in transdermal drug delivery makes the prospect of valid in vitro diffusion cell methodology highly attractive. A new laboratory diffusion cell has been designed and constructed based on theoretical principles and practical permeation reports surveyed in recent literature, and has been applied to the monitoring of betamethasone 17-valerate permeation. The cell performance has been validated with respect to hydrodynamic mixing efficiency and temperature of the receptor phase. The steady-state permeation of this corticosteroid has been monitored through various synthetic and animal membranes in order to select the most appropriate media for in vitro study. The permeation of betamethasone 17-valerate has been monitored from various types of commercial and extemporaneously prepared semisolid topical formulation (cream, lotion, ointment and scalp application), through silicone membrane, human and weanling pig stratum corneum, and full thickness hairless mouse skin, and these in vitro results have been compared to data from in vivo blanching assays, using the same formulations, in an attempt to correlate the findings. This experimental methodology has necessitated the development of ancillary analytical techniques. A column-switching high-performance liquid chromatographic method has been developed for the rapid on-line clean-up and analysis of betamethasone 17-valerate contained in the various topical formulations, which minimizes sample handling and extraction procedures. The method has been modified for the analysis of this corticosteroid in the isopropyl myristate receptor phase used in the in vitro permeation experiments, and scintillation counting of tritium-labelled water has been used to verify the integrity of the animal membranes. The comparison of in vitro permeation and in vivo blanching results indicate good correlation of the data in certain instances. The closest correlations have been observed when the human stratum corneum has been used in vitro and these results are compared to data from the occluded mode of the blanching assay. The results of the porcine and murine media have also correlated with the human in vivo data, whereas the silicone membrane appears applicable only in certain in vitro experiments. The results indicate that valid, comparative percutaneous absorption data may be obtained in vitro by using a well designed, validated diffusion cell system.
- Full Text:
- Authors: Smith, Eric W
- Date: 1988
- Subjects: Transdermal medication Skin absorption Dermatologic agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3815 , http://hdl.handle.net/10962/d1004741
- Description: The current world-wide interest in transdermal drug delivery makes the prospect of valid in vitro diffusion cell methodology highly attractive. A new laboratory diffusion cell has been designed and constructed based on theoretical principles and practical permeation reports surveyed in recent literature, and has been applied to the monitoring of betamethasone 17-valerate permeation. The cell performance has been validated with respect to hydrodynamic mixing efficiency and temperature of the receptor phase. The steady-state permeation of this corticosteroid has been monitored through various synthetic and animal membranes in order to select the most appropriate media for in vitro study. The permeation of betamethasone 17-valerate has been monitored from various types of commercial and extemporaneously prepared semisolid topical formulation (cream, lotion, ointment and scalp application), through silicone membrane, human and weanling pig stratum corneum, and full thickness hairless mouse skin, and these in vitro results have been compared to data from in vivo blanching assays, using the same formulations, in an attempt to correlate the findings. This experimental methodology has necessitated the development of ancillary analytical techniques. A column-switching high-performance liquid chromatographic method has been developed for the rapid on-line clean-up and analysis of betamethasone 17-valerate contained in the various topical formulations, which minimizes sample handling and extraction procedures. The method has been modified for the analysis of this corticosteroid in the isopropyl myristate receptor phase used in the in vitro permeation experiments, and scintillation counting of tritium-labelled water has been used to verify the integrity of the animal membranes. The comparison of in vitro permeation and in vivo blanching results indicate good correlation of the data in certain instances. The closest correlations have been observed when the human stratum corneum has been used in vitro and these results are compared to data from the occluded mode of the blanching assay. The results of the porcine and murine media have also correlated with the human in vivo data, whereas the silicone membrane appears applicable only in certain in vitro experiments. The results indicate that valid, comparative percutaneous absorption data may be obtained in vitro by using a well designed, validated diffusion cell system.
- Full Text:
Aspekte van die Judaïes-Christelike en die Boeddhistiese in die poësie van Breyten Breytenbach
- Authors: Ferreira, Jeanette
- Date: 1988
- Subjects: Breytenbach, Breyten Afrikaans poetry -- History and criticism , Breytenbach, Breyten -- Criticism and interpretation
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3574 , http://hdl.handle.net/10962/d1002097
- Description: Concepts of life and death, time and self-denial are investigated in the poetry of Breyten Breytenbach, with specific reference to the similarities and differences between the Judeo-Christian and the Buddhist traditions. Biblical references in the poetry are examined, and their underlying concepts compared to related concepts in Tantric Buddhism and Zen-Buddhism. The conclusion is drawn that the biblical concepts are transposed in the poetry in order to create Buddhist concepts of life and death, time and a form of self-denial. De-sacralisation of the Christian. concepts is inevitable in this creative process. However, the primary intention of the author is not de-sacralisation, but the implementation 'of the Buddhist philosophy of life in which everything is experienced as "totally one". A comparison between the reconstructed intended reader of Breytenbach's poetry and elements of the Afrikaans reading public suggests that political comment on segregated South African society is intended. Breytenbach's poetry is compared to canonized Afrikaans poetry with respect to Buddhist influence, national protest, aspiration to holiness and transposed biblical concepts. The conclusion is that his poetry is highly innovative in these respects. In the broader spectrum of South African literature his poetry is compared, with reference to transposed biblical concepts and national protest, to the poetry of Black poets writing in English, and (where material is available) to those writing in Afrikaans. The conclusion is that Breytenbach's poetry is strongly linked to this poetry. However, the complexity of Breytenbach's poetry, and the advanced aesthetic level and linguistic code required of the intended reader determine his placing within the canon of Afrikaans poetry.
- Full Text:
- Authors: Ferreira, Jeanette
- Date: 1988
- Subjects: Breytenbach, Breyten Afrikaans poetry -- History and criticism , Breytenbach, Breyten -- Criticism and interpretation
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3574 , http://hdl.handle.net/10962/d1002097
- Description: Concepts of life and death, time and self-denial are investigated in the poetry of Breyten Breytenbach, with specific reference to the similarities and differences between the Judeo-Christian and the Buddhist traditions. Biblical references in the poetry are examined, and their underlying concepts compared to related concepts in Tantric Buddhism and Zen-Buddhism. The conclusion is drawn that the biblical concepts are transposed in the poetry in order to create Buddhist concepts of life and death, time and a form of self-denial. De-sacralisation of the Christian. concepts is inevitable in this creative process. However, the primary intention of the author is not de-sacralisation, but the implementation 'of the Buddhist philosophy of life in which everything is experienced as "totally one". A comparison between the reconstructed intended reader of Breytenbach's poetry and elements of the Afrikaans reading public suggests that political comment on segregated South African society is intended. Breytenbach's poetry is compared to canonized Afrikaans poetry with respect to Buddhist influence, national protest, aspiration to holiness and transposed biblical concepts. The conclusion is that his poetry is highly innovative in these respects. In the broader spectrum of South African literature his poetry is compared, with reference to transposed biblical concepts and national protest, to the poetry of Black poets writing in English, and (where material is available) to those writing in Afrikaans. The conclusion is that Breytenbach's poetry is strongly linked to this poetry. However, the complexity of Breytenbach's poetry, and the advanced aesthetic level and linguistic code required of the intended reader determine his placing within the canon of Afrikaans poetry.
- Full Text:
Cleavage of the precursor coat protein of black beetle virus strain w17 in rabbit reticulocyte lysate
- Authors: Blackhurst, Diane Mary
- Date: 1988
- Subjects: Beetles , Insects -- Viruses
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3880 , http://hdl.handle.net/10962/d1001614
- Description: Black beetle virus (BBV) is a bipartite single-stranded RNA virus belonging to the family Nodaviridae. Its host range has been found to be limited to insects. RNA 1, the larger of the two RNA molecules, with a MW of 1,15 x 10⁶ and the smaller RNA 2 with a MW of 0,46 x 10⁶, are both packaged in the same virus particle. The two RNA molecules are translated separately, with RNA 1 coding for protein A of MW 105 x 10³ and RNA 2 coding for protein α of MW 47 x 10³. Protein α is the major capsid protein precursor, which during in vivo maturation is cleaved to form the coat protein β of MW 43 x 10³, and protein γ of MW 5 x 10³. Cell-free translation of BBV (strain W17) mRNA was carried out in rabbit reticulocyte lysates. Protein α was detectable between 0 and 30 minutes after RNA addition. A protein 'β', which was found to co-electrophorese on polyacrylamide gels with authentic β and which was immunoprecipitated by anti-BBV antiserum, was detectable after 30 minutes. Results of this work show that the formation of 'β' could be prevented by the addition of RNase to the lysate, indicating that intact RNA is necessary for α to β cleavage. Arresting protein synthesis by the addition of cycloheximide to the lysate mix did not inhibit the cleavage. The formation of β could also be prevented by cooling the lysate mix to 1°C. Cleavage of α to β still occurred when RNA 2, without the presence of RNA 1, was translated. Therefore the cleavage is not dependent on a translation product of RNA 1. Sedimentation of lysate on sucrose density gradients showed that α to β cleavage was not accompanied by assembly of BBV RNA and protein lnto a viral substructure as has been shown to occur with some viruses, for example certain picornaviruses. Serial dilution of lysate containing α showed that the level of β decreased with increasing dilution, indicating that the cleavage is not mediated by autocatalysis, but by some other unknown factor. Although much work has been carried out on black beetle virus, no work has been published to date concerning α to β cleavage as an indication of assembly in rabbit reticulocyte lysates. Results of these cell-free translation experiments thus indicate that BBV coat protein precursor α, in association with its messenger RNA 2, undergoes a maturation cleavage in the lysate to produce BBV coat protein β. In addition, this cleavage seems to occur without assembly into any intermediate viral structure
- Full Text:
- Authors: Blackhurst, Diane Mary
- Date: 1988
- Subjects: Beetles , Insects -- Viruses
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3880 , http://hdl.handle.net/10962/d1001614
- Description: Black beetle virus (BBV) is a bipartite single-stranded RNA virus belonging to the family Nodaviridae. Its host range has been found to be limited to insects. RNA 1, the larger of the two RNA molecules, with a MW of 1,15 x 10⁶ and the smaller RNA 2 with a MW of 0,46 x 10⁶, are both packaged in the same virus particle. The two RNA molecules are translated separately, with RNA 1 coding for protein A of MW 105 x 10³ and RNA 2 coding for protein α of MW 47 x 10³. Protein α is the major capsid protein precursor, which during in vivo maturation is cleaved to form the coat protein β of MW 43 x 10³, and protein γ of MW 5 x 10³. Cell-free translation of BBV (strain W17) mRNA was carried out in rabbit reticulocyte lysates. Protein α was detectable between 0 and 30 minutes after RNA addition. A protein 'β', which was found to co-electrophorese on polyacrylamide gels with authentic β and which was immunoprecipitated by anti-BBV antiserum, was detectable after 30 minutes. Results of this work show that the formation of 'β' could be prevented by the addition of RNase to the lysate, indicating that intact RNA is necessary for α to β cleavage. Arresting protein synthesis by the addition of cycloheximide to the lysate mix did not inhibit the cleavage. The formation of β could also be prevented by cooling the lysate mix to 1°C. Cleavage of α to β still occurred when RNA 2, without the presence of RNA 1, was translated. Therefore the cleavage is not dependent on a translation product of RNA 1. Sedimentation of lysate on sucrose density gradients showed that α to β cleavage was not accompanied by assembly of BBV RNA and protein lnto a viral substructure as has been shown to occur with some viruses, for example certain picornaviruses. Serial dilution of lysate containing α showed that the level of β decreased with increasing dilution, indicating that the cleavage is not mediated by autocatalysis, but by some other unknown factor. Although much work has been carried out on black beetle virus, no work has been published to date concerning α to β cleavage as an indication of assembly in rabbit reticulocyte lysates. Results of these cell-free translation experiments thus indicate that BBV coat protein precursor α, in association with its messenger RNA 2, undergoes a maturation cleavage in the lysate to produce BBV coat protein β. In addition, this cleavage seems to occur without assembly into any intermediate viral structure
- Full Text:
Colour and sculpture : an investigation into the use of two dimensional media in sculpture
- Authors: Wright, Jeanne
- Date: 1988
- Subjects: Sculpture -- Technique Sculpture -- History Color in art
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2436 , http://hdl.handle.net/10962/d1004783
- Description: From Introduction: Creative images which are normally called 'art' can be distinguished as either 'plastic' or visual. Both these forms throughout the history of art have relied to a greater or lesser degree on the use of colour. It is my intention to investigate specifically the changing role which colour has played in sculpture - the 'plastic' media of the visual arts and to chart the technical and aesthetic reasons for the use of colour. This investigation will encompass the historical perspective, the material qualities, aesthetic considerations, transitional codes and methods of approach in sociological frameworks and the examination of colour as a metaphysical element in the presentation of three dimensional media.
- Full Text:
- Authors: Wright, Jeanne
- Date: 1988
- Subjects: Sculpture -- Technique Sculpture -- History Color in art
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2436 , http://hdl.handle.net/10962/d1004783
- Description: From Introduction: Creative images which are normally called 'art' can be distinguished as either 'plastic' or visual. Both these forms throughout the history of art have relied to a greater or lesser degree on the use of colour. It is my intention to investigate specifically the changing role which colour has played in sculpture - the 'plastic' media of the visual arts and to chart the technical and aesthetic reasons for the use of colour. This investigation will encompass the historical perspective, the material qualities, aesthetic considerations, transitional codes and methods of approach in sociological frameworks and the examination of colour as a metaphysical element in the presentation of three dimensional media.
- Full Text:
Comparison of the blanching activities of Dermovate, Betnovate and Eumovate creams and ointments
- Meyer, Eric, Magnus, Ashley D, Haigh, John M, Kanfer, Isadore
- Authors: Meyer, Eric , Magnus, Ashley D , Haigh, John M , Kanfer, Isadore
- Date: 1988
- Language: English
- Type: Article
- Identifier: vital:6393 , http://hdl.handle.net/10962/d1006315
- Description: The human skin blanching assay was used to determine the blanching activities of Dermovate, Betnovate and Eumovate creams and ointments. Dermovate was found to elicit a superior blanching response to Betnovate which in turn elicited a superior blanching response to Eumovate, except in the comparison of Betnovate and Eumovate ointments under occlusion. The importance of employing the correct methodology of the blanching assay is emphasized and the good correlation between the results of this study and clinical trials is indicated.
- Full Text: false
- Authors: Meyer, Eric , Magnus, Ashley D , Haigh, John M , Kanfer, Isadore
- Date: 1988
- Language: English
- Type: Article
- Identifier: vital:6393 , http://hdl.handle.net/10962/d1006315
- Description: The human skin blanching assay was used to determine the blanching activities of Dermovate, Betnovate and Eumovate creams and ointments. Dermovate was found to elicit a superior blanching response to Betnovate which in turn elicited a superior blanching response to Eumovate, except in the comparison of Betnovate and Eumovate ointments under occlusion. The importance of employing the correct methodology of the blanching assay is emphasized and the good correlation between the results of this study and clinical trials is indicated.
- Full Text: false
Computer modelling of ore body formation by a multi-disciplinary approach : some initial results
- Rice, A
- Authors: Rice, A
- Date: 1988
- Language: English
- Type: Article
- Identifier: vital:6741 , http://hdl.handle.net/10962/d1007557
- Description: Reports on the initial efforts of a computational programme at Rhodes University in Cape Province, South Africa to model the formation of mineral deposits in the country. Initial results pertaining to the cooling of buried bodies of molten rock; Contribution to a better margin of success for South African mineral industries.
- Full Text:
- Authors: Rice, A
- Date: 1988
- Language: English
- Type: Article
- Identifier: vital:6741 , http://hdl.handle.net/10962/d1007557
- Description: Reports on the initial efforts of a computational programme at Rhodes University in Cape Province, South Africa to model the formation of mineral deposits in the country. Initial results pertaining to the cooling of buried bodies of molten rock; Contribution to a better margin of success for South African mineral industries.
- Full Text:
Concept development in aspects of ecology
- Authors: Webb, Paul
- Date: 1988
- Subjects: Ecology -- Study and teaching
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: vital:1354 , http://hdl.handle.net/10962/d1001420
- Description: In this study food webs and a case study are used to investigate concepts which university students and high school pupils hold about ecology and the degree to which concept development has taken place at particular educational levels. The sample was drawn from first year zoology students and biology pupils in standards eight and ten. Present data indicate that students and pupils could solve problems involving the interactions of populations only if they were simple enough to be answered using strategies based on the food chain concept. Very few subjects could succesfully determine all the interacting pathways along which effects may be transmitted within a food web. The ability to determine all the pathways along which the effects of a change in population numbers within a community are spread, and to analyse the possible net manifestation of sometimes conflicting forces, requires a clear understanding of the concept of food web. An immature understanding of the food web concept by the subjects of this study is suggested as, in most cases, they identified alternate pathways within the food web when explicitly asked to do so, but did not apply this strategy when asked to solve problems based on the same principle. The case study also revealed immature ecological concepts. Responses by standard eight pupils indicate that the opportunity exists at this level to develop a clear and mature understanding of the concept of food web, while comparison of data provided by the three age groups suggests that if clear conceptual development regarding food webs does not take place at school, misconceptions are likely to persist among first year university students.
- Full Text:
- Authors: Webb, Paul
- Date: 1988
- Subjects: Ecology -- Study and teaching
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: vital:1354 , http://hdl.handle.net/10962/d1001420
- Description: In this study food webs and a case study are used to investigate concepts which university students and high school pupils hold about ecology and the degree to which concept development has taken place at particular educational levels. The sample was drawn from first year zoology students and biology pupils in standards eight and ten. Present data indicate that students and pupils could solve problems involving the interactions of populations only if they were simple enough to be answered using strategies based on the food chain concept. Very few subjects could succesfully determine all the interacting pathways along which effects may be transmitted within a food web. The ability to determine all the pathways along which the effects of a change in population numbers within a community are spread, and to analyse the possible net manifestation of sometimes conflicting forces, requires a clear understanding of the concept of food web. An immature understanding of the food web concept by the subjects of this study is suggested as, in most cases, they identified alternate pathways within the food web when explicitly asked to do so, but did not apply this strategy when asked to solve problems based on the same principle. The case study also revealed immature ecological concepts. Responses by standard eight pupils indicate that the opportunity exists at this level to develop a clear and mature understanding of the concept of food web, while comparison of data provided by the three age groups suggests that if clear conceptual development regarding food webs does not take place at school, misconceptions are likely to persist among first year university students.
- Full Text:
Criminal and civil aspects of bribery
- Authors: Leslie, Andrew Brian
- Date: 1988
- Subjects: Bribery
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3701 , http://hdl.handle.net/10962/d1004607
- Description: The purpose of this work is to identify legal action which may be taken against parties to bribery in the fields of criminal and civil law. In particular, the element of mens rea is investigated with regard to criminal corruption. On the civil side, the principal, who has been the victim of bribery, has various remedies against the parties to the bribe. These remedies are analysed with special reference to the influence of English law on the South African law in this field. The options open to the principal, where his agent has made a secret profit which does not amount to bribery, are also considered.
- Full Text:
- Authors: Leslie, Andrew Brian
- Date: 1988
- Subjects: Bribery
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3701 , http://hdl.handle.net/10962/d1004607
- Description: The purpose of this work is to identify legal action which may be taken against parties to bribery in the fields of criminal and civil law. In particular, the element of mens rea is investigated with regard to criminal corruption. On the civil side, the principal, who has been the victim of bribery, has various remedies against the parties to the bribe. These remedies are analysed with special reference to the influence of English law on the South African law in this field. The options open to the principal, where his agent has made a secret profit which does not amount to bribery, are also considered.
- Full Text:
Defined by wine : a study of sacramentalism in George Herbertʾs poetry
- Authors: Goddard, Kevin Graham
- Date: 1988
- Subjects: Herbert, George, 1593-1633 -- Criticism and interpretation , Christian poetry, English -- History and criticism
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:2177 , http://hdl.handle.net/10962/d1001828
- Description: This dissertation proposes that George Herbertʾs poetry may profitably be understood as a sacramental means by which the divine is made present in temporal existence. In order to support this claim, the relation between sacramental symbolism and literary symbolism, particularly Herbertʾs, is examined from a number of perspectives. The symbolic meanings suggested by Herbertʾs title (The Temple), and their relation to sacramentalism are considered in the opening chapter. This includes a consideration of some of the background to the analogical thinking prevalent in both the seventeenth-century and Herbert. It is followed in the second chapter by an examination of some of the modern theories about how literary symbolism may relate to sacramental symbolism, a discussion which is followed by a consideration of this dissertation's argument in relation to modern scholarship. The chapter ends with a reading of ʺThe Flowerʺ. The third chapter discusses the poet's attempt to imitate the divine by ʺcopyingʺ both Scripture and Nature, and this includes a consideration of the allegorical and hieroglyphic modes of thought prevalent in the poems. The concern with imitation encourages an examination of the poet's frequent invitation for God actually to assume the poet's role, and this is the subject of the fourth chapter. The argument suggests that the poet's attempt to ʺsacrificeʺ his own writing may be seen in his concern with corporate imagery and corporate (impersonal) structures. The five ʺAfflictionʺ poems are examined as examples of the first, while structures such as synecdoche and metonymy are examined as examples of the second. The final chapter considers aspects of narrative time in the poems, particularly the sense often evoked of the eternal being imminent in the present. This involves a consideration of both liturgical imagery, and what may be called liturgical structures as they can be seen to operate in the poems. Particular examples of the latter are the relation between the liturgical anamnesis and the poems, as well as certain narrative structures that may be called ʺachronisticʺ.
- Full Text:
- Authors: Goddard, Kevin Graham
- Date: 1988
- Subjects: Herbert, George, 1593-1633 -- Criticism and interpretation , Christian poetry, English -- History and criticism
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:2177 , http://hdl.handle.net/10962/d1001828
- Description: This dissertation proposes that George Herbertʾs poetry may profitably be understood as a sacramental means by which the divine is made present in temporal existence. In order to support this claim, the relation between sacramental symbolism and literary symbolism, particularly Herbertʾs, is examined from a number of perspectives. The symbolic meanings suggested by Herbertʾs title (The Temple), and their relation to sacramentalism are considered in the opening chapter. This includes a consideration of some of the background to the analogical thinking prevalent in both the seventeenth-century and Herbert. It is followed in the second chapter by an examination of some of the modern theories about how literary symbolism may relate to sacramental symbolism, a discussion which is followed by a consideration of this dissertation's argument in relation to modern scholarship. The chapter ends with a reading of ʺThe Flowerʺ. The third chapter discusses the poet's attempt to imitate the divine by ʺcopyingʺ both Scripture and Nature, and this includes a consideration of the allegorical and hieroglyphic modes of thought prevalent in the poems. The concern with imitation encourages an examination of the poet's frequent invitation for God actually to assume the poet's role, and this is the subject of the fourth chapter. The argument suggests that the poet's attempt to ʺsacrificeʺ his own writing may be seen in his concern with corporate imagery and corporate (impersonal) structures. The five ʺAfflictionʺ poems are examined as examples of the first, while structures such as synecdoche and metonymy are examined as examples of the second. The final chapter considers aspects of narrative time in the poems, particularly the sense often evoked of the eternal being imminent in the present. This involves a consideration of both liturgical imagery, and what may be called liturgical structures as they can be seen to operate in the poems. Particular examples of the latter are the relation between the liturgical anamnesis and the poems, as well as certain narrative structures that may be called ʺachronisticʺ.
- Full Text:
Dilution of topical corticosteroid formulations
- Authors: Haigh, John M
- Date: 1988
- Language: English
- Type: text , Article
- Identifier: vital:6377 , http://hdl.handle.net/10962/d1006295
- Description: It has been a long-held concern of a number of people working in this field that some dermatologists prescribing a 1:10 dilution of a corticosteroid preparation such as Dermovate cream believe that the final product will be one tenth as efficacious and also produce one tenth of the side effects as the undiluted formulation. This is certainly not the case. Dermovate falls into the very potent category of topical corticosteroid preparations (as defined in the United Kingdom Monthly Index of Medical Specialities) and a 1:10 dilution falls into the potent category.
- Full Text:
- Authors: Haigh, John M
- Date: 1988
- Language: English
- Type: text , Article
- Identifier: vital:6377 , http://hdl.handle.net/10962/d1006295
- Description: It has been a long-held concern of a number of people working in this field that some dermatologists prescribing a 1:10 dilution of a corticosteroid preparation such as Dermovate cream believe that the final product will be one tenth as efficacious and also produce one tenth of the side effects as the undiluted formulation. This is certainly not the case. Dermovate falls into the very potent category of topical corticosteroid preparations (as defined in the United Kingdom Monthly Index of Medical Specialities) and a 1:10 dilution falls into the potent category.
- Full Text:
Discussing the evidence : small group work in the history class
- Robinson, Andrew Meredith Lewin
- Authors: Robinson, Andrew Meredith Lewin
- Date: 1988
- Subjects: History -- Study and teaching (Secondary) Group work in education
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1863 , http://hdl.handle.net/10962/d1004588
- Description: This is a small-scale research study on the discovery method of teaching history through the medium of small-group discussion. The study begins with a brief outline of the theoretical background to these topics, as well as of some of the extant research in the field. The class selected for the study is the standard seven class of a boys' high school. After the researcher has instructed the whole standard in an historical area which is unfamiliar to the pupils, twelve groups of three each are selected and withdrawn from the rest of the class, one group at a time. These thirty-six pupils become the "experimental" group; the rest of the pupils become the "control" group . The groups are selected according to different intellectual criteria and presented with stimulus material of one of three kinds, which is intended to aid them in their discourse. Each group is given the same set of three questions to discuss and, without further assistance by the researcher, the discussion takes place. This is recorded on audio-tape. After all the group discussions have been recorded, an assessment test is given to the whole standard, both experimental and control pupils. At the end of the school term a compulsory examination question is inserted in the history examination. The statistical data forthcoming from these assessments are correlated and the results analysed. Meanwhile, transcripts of all the group discussions have been made and these are analysed on a qualitative basis in terms of the groups' intellectual composition and according to the type of stimulus material used, and the results are recorded. The concept of "leaderless" groups is briefly discussed in the light of the dealings of the various groups in the study. The researcher finally feels justified in concluding that small groups are an ideal medium for the handling of evidence- based learning in history. He also has certain observations to make on the performance of groups of mixed (as opposed to homogeneous) ability as well as on the success of certain types of stimulus material towards initiating profitable discussion.
- Full Text:
- Authors: Robinson, Andrew Meredith Lewin
- Date: 1988
- Subjects: History -- Study and teaching (Secondary) Group work in education
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1863 , http://hdl.handle.net/10962/d1004588
- Description: This is a small-scale research study on the discovery method of teaching history through the medium of small-group discussion. The study begins with a brief outline of the theoretical background to these topics, as well as of some of the extant research in the field. The class selected for the study is the standard seven class of a boys' high school. After the researcher has instructed the whole standard in an historical area which is unfamiliar to the pupils, twelve groups of three each are selected and withdrawn from the rest of the class, one group at a time. These thirty-six pupils become the "experimental" group; the rest of the pupils become the "control" group . The groups are selected according to different intellectual criteria and presented with stimulus material of one of three kinds, which is intended to aid them in their discourse. Each group is given the same set of three questions to discuss and, without further assistance by the researcher, the discussion takes place. This is recorded on audio-tape. After all the group discussions have been recorded, an assessment test is given to the whole standard, both experimental and control pupils. At the end of the school term a compulsory examination question is inserted in the history examination. The statistical data forthcoming from these assessments are correlated and the results analysed. Meanwhile, transcripts of all the group discussions have been made and these are analysed on a qualitative basis in terms of the groups' intellectual composition and according to the type of stimulus material used, and the results are recorded. The concept of "leaderless" groups is briefly discussed in the light of the dealings of the various groups in the study. The researcher finally feels justified in concluding that small groups are an ideal medium for the handling of evidence- based learning in history. He also has certain observations to make on the performance of groups of mixed (as opposed to homogeneous) ability as well as on the success of certain types of stimulus material towards initiating profitable discussion.
- Full Text:
Distribution and petrogenesis of the basic rocks of the Etendeka Formation of northwestern Namibia
- Marsh, Julian S, Duncan, Andrew R, Milner, Simon C, Erlank, Anthony J
- Authors: Marsh, Julian S , Duncan, Andrew R , Milner, Simon C , Erlank, Anthony J
- Date: 1988
- Language: English
- Type: text , abstracts
- Identifier: http://hdl.handle.net/10962/131667 , vital:36709
- Description: The igneous rocks which comprise the Etendeka Formation in northwestern Namibia cover an area of 78 000 km² and consist dominantly of interbedded basalts and quartz latites, with minor latites. They are spatially associated with, and intruded by, two suites of dolerites. The rocks of the Etendeka Formation are included in the Karoo Igneous Province but differ from most other Karoo volcanics with respect to their younger age (Cretaceous) and aspects of their mineralogy and geochemistry.
- Full Text:
- Authors: Marsh, Julian S , Duncan, Andrew R , Milner, Simon C , Erlank, Anthony J
- Date: 1988
- Language: English
- Type: text , abstracts
- Identifier: http://hdl.handle.net/10962/131667 , vital:36709
- Description: The igneous rocks which comprise the Etendeka Formation in northwestern Namibia cover an area of 78 000 km² and consist dominantly of interbedded basalts and quartz latites, with minor latites. They are spatially associated with, and intruded by, two suites of dolerites. The rocks of the Etendeka Formation are included in the Karoo Igneous Province but differ from most other Karoo volcanics with respect to their younger age (Cretaceous) and aspects of their mineralogy and geochemistry.
- Full Text:
Effects of vitamin A on tumour and untransformed cells
- Authors: De Villiers, Diane Lynette
- Date: 1988
- Subjects: Vitamin A , Vitamin A in the body , Cancer -- Prevention
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3881 , http://hdl.handle.net/10962/d1001615
- Description: Vitamin A and its chemical analogues (retinoids) are known to play a role in the maintenance and differentiation of epithelial tissue. Retinoids have been shown to inhibit carcinogenesis in a number of tissues in experimental animals and to inhibit the growth of various untransformed and cancer cell lines in vitro. This study investigated the effect of retinyl acetate supplemented at concentrations of 1 μM, 5 μM, 10 μM and 100 μM to in vitro cultured untransformed LLCMK cells, and transformed BL-6 melanoma and human hepatoma cell lines. A small but non-significant effect of vitamin A addition on the growth of the untransformed cells was observed, while substantial inhibition of proliferation of the two tumour cell lines was found. At the cytotoxic level of 100 μM supplemented vitamin A, all three cell lines showed marked inhibition of growth. This led to an electron microscopy study to examine the ultrastructural effect of the vitamin A addition. At the low non-toxic levels of vitamin A addition (1 - 10 μM), no ultrastructural changes were observed in the untransformed cells. However, at a level of 5 μM and 10 μM vitamin A addition in the tumour cells, an increase in the size of suspected lipid droplets was observed. At the cytotoxic level of 100 μM supplemented vitamin A, large lipid droplets were very apparent, as was much cellular degeneration. This effect was more marked in the tumour cells than in the untransformed cells. The lipid nature of the droplets was confirmed by using the lipid stain, Sudan IV. In order to investigate the effect of added vitamin A at the cell surface level, an ELISA system was used to quantify the level of the cell surface glycoprotein, fibronectin, in the culture media. Vitamin A plays an important role in the production of mature fibronectin by participating in the glycosylation of the molecule. This study showed no major effect of added vitamin A on the release of fibronectin into the culture media. This did not, however, exclude the possibility that the vitamin A was involved in the production and enhanced binding of fibronectin to the cell surface, and was possibly also exerting an effect on the availability of fibronectin receptors. Further studies would, however, be required to substantiate such effects of vitamin A supplementation. No single mechanism of action of vitamin A on tumour cell growth inhibition was identified, but the possibility that at least two mechanisms exist, was suggested
- Full Text:
- Authors: De Villiers, Diane Lynette
- Date: 1988
- Subjects: Vitamin A , Vitamin A in the body , Cancer -- Prevention
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3881 , http://hdl.handle.net/10962/d1001615
- Description: Vitamin A and its chemical analogues (retinoids) are known to play a role in the maintenance and differentiation of epithelial tissue. Retinoids have been shown to inhibit carcinogenesis in a number of tissues in experimental animals and to inhibit the growth of various untransformed and cancer cell lines in vitro. This study investigated the effect of retinyl acetate supplemented at concentrations of 1 μM, 5 μM, 10 μM and 100 μM to in vitro cultured untransformed LLCMK cells, and transformed BL-6 melanoma and human hepatoma cell lines. A small but non-significant effect of vitamin A addition on the growth of the untransformed cells was observed, while substantial inhibition of proliferation of the two tumour cell lines was found. At the cytotoxic level of 100 μM supplemented vitamin A, all three cell lines showed marked inhibition of growth. This led to an electron microscopy study to examine the ultrastructural effect of the vitamin A addition. At the low non-toxic levels of vitamin A addition (1 - 10 μM), no ultrastructural changes were observed in the untransformed cells. However, at a level of 5 μM and 10 μM vitamin A addition in the tumour cells, an increase in the size of suspected lipid droplets was observed. At the cytotoxic level of 100 μM supplemented vitamin A, large lipid droplets were very apparent, as was much cellular degeneration. This effect was more marked in the tumour cells than in the untransformed cells. The lipid nature of the droplets was confirmed by using the lipid stain, Sudan IV. In order to investigate the effect of added vitamin A at the cell surface level, an ELISA system was used to quantify the level of the cell surface glycoprotein, fibronectin, in the culture media. Vitamin A plays an important role in the production of mature fibronectin by participating in the glycosylation of the molecule. This study showed no major effect of added vitamin A on the release of fibronectin into the culture media. This did not, however, exclude the possibility that the vitamin A was involved in the production and enhanced binding of fibronectin to the cell surface, and was possibly also exerting an effect on the availability of fibronectin receptors. Further studies would, however, be required to substantiate such effects of vitamin A supplementation. No single mechanism of action of vitamin A on tumour cell growth inhibition was identified, but the possibility that at least two mechanisms exist, was suggested
- Full Text:
English in Africa 2000 : towards a new millennium : inaugural lecture delivered at Rhodes University
- Authors: Walters, Paul S
- Date: 1988
- Subjects: Molteno Project , English language -- Study and teaching -- South Africa , English language -- Usage -- South Africa
- Language: English
- Type: Text
- Identifier: vital:678 , http://hdl.handle.net/10962/d1020747 , ISBN 0868101680
- Description: Inaugural lecture delivered at Rhodes University , Rhodes University Libraries (Digitisation)
- Full Text:
English in Africa 2000 : towards a new millennium : inaugural lecture delivered at Rhodes University
- Authors: Walters, Paul S
- Date: 1988
- Subjects: Molteno Project , English language -- Study and teaching -- South Africa , English language -- Usage -- South Africa
- Language: English
- Type: Text
- Identifier: vital:678 , http://hdl.handle.net/10962/d1020747 , ISBN 0868101680
- Description: Inaugural lecture delivered at Rhodes University , Rhodes University Libraries (Digitisation)
- Full Text: